Dr. McAnulty is an Associate Professor of Surgery at the School of Veterinary Medicine, University of Wisconsin-Madison. He is a general surgeon with expertise in microvascular surgery, solid organ transplantation, and organ preservation. Dr. McAnulty, in collaboration with Dr. Christopher Murphy, has validated a model of delayed skin wound healing for the testing of compounds that stimulate the healing of wounds.
Craniectomies for Dogs With Skull Multilobular Osteochondrosarcoma Using the Misonix Bone Scalpel: Cadaveric Evaluation and Retrospective Case Series
Top Companion Anim Med. 2023 Mar 28;53-54:100772. doi: 10.1016/j.tcam.2023.100772. Online ahead of print.
To evaluate the Misonix bone scalpel (MBS) for craniotomies in dogs and describe clinical findings and surgical experience in 3 dogs with large multilobular osteochondrosarcoma (MLO) of the skull. Cadaver evaluation and retrospective case series. One canine cadaver; 3 client-owned dogs. Craniotomies of different sizes and at different locations were performed with MBS. Dural tear and bone discoloration were recorded. Clinical, imaging, and surgical findings of dogs diagnosed with MLO and where MBS was used for craniectomies were retrospectively included. Cadaveric evaluation identified MBS as an efficient tool for rapid craniectomies (>5minutes) albeit dural tears and some small foci of bone discoloration were observed. Craniectomies could be performed without complications in 3 dogs with MLO without dural tear or bone discoloration. .Excision was in complete in all cases. The short-term outcome was good, and the long-term outcome was fair to good. Piezoelectric bone surgery with the Misonix bone scalpel is an alternative technology to perform craniectomies in dogs. It was not associated with complications in 3 dogs diagnosed and surgically treated for MLO. Dural tears and suspected bone necrosis can occur. Great care should be taken when using CT to establish disease free surgical osteotomy.
PMID:36990178 | DOI:10.1016/j.tcam.2023.100772
Sustained Release of a Synthetic Autoinducing Peptide Mimetic Blocks Bacterial Communication and Virulence In Vivo
Angew Chem Int Ed Engl. 2022 Mar 25;61(24):e202201798. doi: 10.1002/anie.202201798. Online ahead of print.
A synthetic peptide was found to block cell-to-cell signalling, or quorum sensing, in bacteria and be highly bioavailable in mouse tissue. The controlled release of this agent from degradable polymeric microparticles strongly inhibited skin infection in a wound model at levels that far surpassed the potency of the peptide when delivered conventionally.
PMID:35334139 | PMC:PMC9322450 | DOI:10.1002/anie.202201798
The development of ventricular fibrillation as a complication of pericardiectomy in 16 dogs
Vet Surg. 2022 May;51(4):611-619. doi: 10.1111/vsu.13795. Epub 2022 Mar 7.
OBJECTIVE: To describe the clinical characteristics, perioperative protocols, and outcomes in dogs diagnosed with ventricular fibrillation (VF) while undergoing pericardiectomy.
STUDY DESIGN: Retrospective, multi-institutional study.
ANIMALS: Sixteen client-owned dogs.
METHODS: Cases were accrued through a listserve request posted to 3 subspecialty veterinary societies. Dogs were included if they developed VF during a pericardiectomy performed through an open or thoracoscopic approach. Data collected included signalment, history and physical examination, surgical approach, histopathology, treatment, and outcome.
RESULTS: Indications for pericardiectomy included idiopathic chylothorax (n = 7), neoplasia (4), idiopathic pericardial effusion (4), and foreign body granuloma (1). Surgical approaches included thoracoscopy (12), intercostal thoracotomy (3) and median sternotomy (1). Electrosurgical devices were used to complete at least part of the pericardiectomy in 15 of 16 dogs. Ventricular fibrillation appeared to be initiated during electrosurgical use in 8/15 dogs. However, in 5/15 dogs it was not obviously associated with electrosurgical use. In 3/16 dogs the timing of initiation of VF was unclear. In 7/16 dogs, cardiac arrhythmias were noted prior to the development of VF. Fourteen of 16 dogs died from intraoperative VF.
CONCLUSION: In most dogs ventricular fibrillation was a fatal complication of pericardiectomy. Ventricular fibrillation might be associated with the use of electrosurgical devices and cardiac manipulation during pericardiectomy although a causal link could not be established from the data in this study.
CLINICAL SIGNIFICANCE: Surgeons must be aware of the risk of VF during pericardial surgery. Electrosurgery might need to be used judiciously during pericardiectomy, particularly in dogs exhibiting cardiac arrythmias.
PMID:35257394 | DOI:10.1111/vsu.13795
Retroperitoneal fibrosis as a postoperative complication following renal transplantation in cats
J Feline Med Surg. 2022 Apr;24(4):304-310. doi: 10.1177/1098612X211018976. Epub 2021 May 21.
OBJECTIVES: The aim of this report was to describe the clinical signs, diagnostic imaging findings, surgical management, histopathological findings, outcome and possible risk factors for cats that developed retroperitoneal fibrosis (RPF) following renal transplantation.
METHODS: Medical records of cats that underwent renal transplantation and developed clinically significant RPF between 1995 and 2019 were reviewed.
RESULTS: Eighty-one cats underwent 83 renal transplantations. Of these 81 cats, six developed clinically significant RPF. For all six cats, renal transplantation was performed using cold organ preservation solution and ureteral papilla implantation. Immunosuppression protocol included ciclosporin and prednisolone. All cats had at least one subtherapeutic trough ciclosporin level (<250 ng/ml) in the postoperative period. Cats presented with moderate-to-severe azotemia 39-210 days following renal transplantation. Abdominal ultrasonography and contrast pyelography revealed various degrees of hydroureter and hydronephrosis of the transplanted kidney. Surgical examination revealed a layer of dense fibrous tissue surrounding the transplanted kidney, ureter and bladder resulting in ureteral obstruction. Ureteral obstruction was managed by reimplantation of the proximal ureter or renal pelvis to the bladder. Histopathologic examination of the fibrous tissue and affected portion of the distal ureter revealed fibrous connective tissue with lymphoplasmacytic infiltration and perivascular inflammation suggestive of an autoimmune type reaction. Of the six cats, two died within 5 days after revision surgery, two developed signs consistent with recurrent partial ureteral obstruction (40 and 41 days after revision), one was euthanized 6 years later for an unrelated disease and one was lost to follow-up.
CONCLUSIONS AND RELEVANCE: The incidence of RPF in this population of cats was relatively low (7%), but still represents a significant cause of morbidity and mortality. The cause of RPF remains unknown, although investigation into suboptimal immunosuppression as a potential cause for local rejection reaction is warranted.
PMID:34018858 | DOI:10.1177/1098612X211018976
Dorsal offset rhinoplasty for treatment of stenotic nares in 34 brachycephalic dogs
Vet Surg. 2020 Dec;49(8):1497-1502. doi: 10.1111/vsu.13504. Epub 2020 Aug 27.
OBJECTIVE: To describe the technique, outcome, and owner satisfaction associated with dorsal offset rhinoplasty (DOR) to treat stenotic nares in brachycephalic dogs.
STUDY DESIGN: Retrospective case series.
ANIMALS: Thirty-four client-owned dogs.
METHODS: Medical records of dogs treated with DOR at a veterinary teaching hospital over a 6-year period were identified. Dorsal offset rhinoplasty was defined as removal of a dorsal wedge of nasal planum from each naris with apposition of the rostral abaxial tissue to the caudal axial tissue, resulting in translocation of the alar cartilage in both median and dorsal planes. Immediate and postoperative complications were recorded. Owners were asked to report any complications with healing of the nares and to score their satisfaction with the appearance of the nares.
RESULTS: Thirty-four dogs met the inclusion criteria. Twenty-nine (85%) dogs were examined a median of 402.5 days (range, 23-2042) postoperatively, with no major complications related to the rhinoplasty recorded. Eighteen owners responded a median of 701 days (range, 37-1622) postoperatively. One owner reported that self-trauma led to collapse of one naris. One owner reported collapse of both nares within 4 years; timing and cause were unknown. Sixteen of 17 responding owners reported that they were very satisfied with the outcome of the rhinoplasty. The owner of the dog with the collapsed naris was very unsatisfied. One owner did not provide a satisfaction score.
CONCLUSION: Owners were generally highly satisfied with DOR, and complications were uncommon.
CLINICAL SIGNIFICANCE: This report describes an alternate technique to treat stenotic nares.
PMID:32853422 | DOI:10.1111/vsu.13504
Catheter occlusion of the dorsal sagittal sinus-confluens sinuum to enable resection of lateral occipital multilobular osteochondrosarcoma in two dogs
J Am Vet Med Assoc. 2019 Apr 1;254(7):843-851. doi: 10.2460/javma.254.7.843.
CASE DESCRIPTION: A 6-year-old neutered male mixed-breed dog (dog 1) and 5-year-old neutered male Boston Terrier (dog 2) were evaluated because of lateralized multilobular osteochondrosarcoma (MLO) of the occiput.
CLINICAL FINDINGS: Diagnostic imaging revealed proliferative bony occipital masses in both dogs and a nodule in the right caudal lung lobe of dog 1. For both dogs, MRI revealed intact flow through the dorsal sagittal sinus (DSS) into 1 transverse sinus.
TREATMENT AND OUTCOME: In dog 1, a 4F balloon catheter was introduced into the DSS to the confluens sinuum (CS) and inflated over 16 hours to occlude venous flow. The mass with the CS was removed 24 hours later, and the skull was reconstructed. The dog was discharged from the hospital 2 days after surgery and survived 17 months before euthanasia because of metastasis. In dog 2, balloon catheter insertion into the DSS failed, and a 3.5F rubber catheter was placed up to the CS to occlude flow. The occiput with MLO was removed 48 hours after catheterization, and the skull was reconstructed. Dog 2 was discharged from the hospital after 3 days and was doing well 15 months later.
CLINICAL RELEVANCE: Findings for these 2 dogs suggested that deliberate preoperative occlusion of the DSS and CS allows successful resection of occipital neoplasms across the midline. Without prior occlusion of the DSS, development of lethal cerebral edema would have been likely. Gradual balloon catheter occlusion of the CS may facilitate challenging occipital mass excisions.
PMID:30888273 | DOI:10.2460/javma.254.7.843
Novel murine model for delayed wound healing using a biological wound dressing with Pseudomonas aeruginosa biofilms
Microb Pathog. 2018 Sep;122:30-38. doi: 10.1016/j.micpath.2018.05.043. Epub 2018 May 26.
Bacterial biofilms impair healing in 60% of chronic skin wounds. Various animal models (mice, rats, rabbits, and pigs) have been developed to replicate biofilm infected wounds in vivo. We developed a sustained wound infection model by applying preformed Pseudomonas aeruginosa biofilms on a wound dressing to full-thickness murine skin wounds. We bathed a commercially available wound dressing in P. aeruginosa for 48 h, allowing a biofilm to establish on the dressing prior to application to the wound. Dressings were removed from the wounds after 3 days at which time the wound beds contained ∼108 bacterial cells per gram tissue. Significant numbers of P. aeruginosa persisted within the skin wounds for up to 21 days. Un-inoculated wounds reached closure between 9 and 12 days. In contrast, biofilm-inoculated wounds achieved closure between 18 and 21 days. Histologic analysis confirmed decreased re-epithelialization and collagen deposition, coupled with increased inflammation, in the biofilm-inoculated wounds compared to un-inoculated controls. This novel model of delayed healing and persistent infection of full-thickness murine skin wounds may provide a robust in vivo system in which to test novel treatments to prevent wound infection by bacterial biofilms.
PMID:29842898 | DOI:10.1016/j.micpath.2018.05.043
A Carrel patch technique for renal transplantation in cats
Vet Surg. 2017 Nov;46(8):1139-1144. doi: 10.1111/vsu.12705. Epub 2017 Aug 31.
OBJECTIVE: To evaluate the feasibility of a Carrel patch method in feline renal transplantation.
STUDY DESIGN: Descriptive case series.
ANIMALS: Nine healthy donor cats and 9 client recipient cats with chronic renal failure.
METHODS: Renal transplantation was performed in 9 cats with chronic renal failure after collection of a donor's left kidney with a Carrel patch technique. A patch of donor aortic wall was removed with either 2 or 1 renal artery (ies) (n = 1 and 8 cats, respectively) central to the patch, with a cuff of tissue (≤1 mm) protruding from the base of the vessels. The Carrel patch was implanted in recipient cats with an end-to-side artery-to-aorta anastomosis, in a simple-continuous pattern of 9-0 nylon. The renal vein and ureter were implanted as previously described.
RESULTS: All donors and recipients survived surgery without vascular complication.
CONCLUSION: The Carrel patch is a novel approach allowing the harvest of kidneys with multiple renal arteries. The technique also simplified the implant procedure, potentially decreasing the risks of bleeding and thrombosis.
PMID:28858383 | DOI:10.1111/vsu.12705
Effect of cold storage on immediate graft function in an experimental model of renal transplantation in cats
Am J Vet Res. 2017 Mar;78(3):330-339. doi: 10.2460/ajvr.78.3.330.
OBJECTIVE To assess the effect of cold storage (CS) on immediate posttransplantation function of renal autografts in cats. ANIMALS 15 healthy 1-year-old cats. PROCEDURES Cats were assigned to 2 groups and underwent autotransplantation of the left kidney followed by nephrectomy of the right kidney. The left kidney was autotransplanted either immediately (IT group; n = 6) or after being flushed with a cold sucrose phosphate solution and stored on ice while the implant site was prepared (CS group; 9). Serum creatinine and BUN concentrations were monitored daily and autografts were ultrasonographically examined intermittently for 14 days after surgery. RESULTS Mean duration of CS was 24 minutes for the CS group. Posttransplantation serum creatinine and BUN concentrations for the CS group had lower peak values, returned to the respective reference ranges quicker, and were generally significantly lower than those for the IT group. Mean posttransplantation autograft size for the CS group was smaller than that for the IT group. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that immediate posttransplantation function of renal autografts following a short period of CS was better than that of renal autografts that did not undergo CS, which suggested CS protected grafts from ischemic injury and may decrease perioperative complications, speed recovery, and improve the long-term outcome for cats with renal transplants. IMPACT FOR HUMAN MEDICINE Cats metabolize immunosuppressive drugs in a manner similar to humans; therefore, renal transplantation in cats may serve as a desirable model for investigating the effects of renal transplantation in human patients.
PMID:28240954 | DOI:10.2460/ajvr.78.3.330
Interfacial Stacks of Polymeric Nanofilms on Soft Biological Surfaces that Release Multiple Agents
ACS Appl Mater Interfaces. 2016 Oct 12;8(40):26541-26551. doi: 10.1021/acsami.6b08608. Epub 2016 Oct 3.
We report a general and facile method that permits the transfer (stacking) of multiple independently fabricated and nanoscopically thin polymeric films, each containing a distinct bioactive agent, onto soft biomedically relevant surfaces (e.g., collagen-based wound dressings). By using polyelectrolyte multilayer films (PEMs) formed from poly(allyl amine hydrochloride) and poly(acrylic acid) as representative polymeric nanofilms and micrometer-thick water-soluble poly(vinyl alcohol) sacrificial films to stack the PEMs, we demonstrate that it is possible to create stacked polymeric constructs containing multiple bioactive agents (e.g., antimicrobial and antibiofilm agents) on soft and chemically complex surfaces onto which PEMs cannot be routinely transferred by stamping. We illustrate the characteristics and merits of the approach by fabricating stacks of Ga3+ (antibiofilm agent)- and Ag+ (antimicrobial agent)-loaded PEMs as prototypical examples of agent-containing PEMs and demonstrate that the stacked PEMs incorporate precise loadings of the agents and provide flexibility in terms of tuning release rates. Specifically, we show that simultaneous release of Ga3+ and Ag+ from the stacked PEMs on collagen-based wound dressings can lead to synergistic effects on bacteria, killing and dispersing biofilms formed by Pseudomonas aeruginosa (two strains: ATCC 27853 and MPAO1) at sufficiently low loadings of agents such that cytotoxic effects on mammalian cells are avoided. The approach is general (a wide range of bioactive agents other than Ga3+ and Ag+ can be incorporated into PEMs), and the modular nature of the approach potentially allows end-user functionalization of soft biological surfaces for programmed release of multiple bioactive agents.
PMID:27579573 | DOI:10.1021/acsami.6b08608
Ureteral Papilla Implantation as a Technique for Neoureterocystostomy in Cats Undergoing Renal Transplantation: 30 Cases
Vet Surg. 2016 May;45(4):443-9. doi: 10.1111/vsu.12476.
OBJECTIVE: To describe the clinical outcome of donor and recipient cats undergoing ureteral papilla harvest and implantation as a technique for neoureterocystostomy in clinical kidney transplant.
STUDY DESIGN: Retrospective case series.
ANIMALS: Donor (n=31) and recipient (n=30) cats that underwent kidney harvest and transplantation using ureteral papilla implantation technique for neoureterocystostomy.
METHODS: Medical records for donor and recipient cats presented to the University of Wisconsin Veterinary Teaching Hospital from January 2003 to December 2014 were reviewed. Data recorded included complete blood count, serum chemistry panel, surgical technique, diagnostic imaging results, short- and long-term complications, and anesthetic survival.
RESULTS: All 30 recipients recovered from anesthesia. Four died within 24 hours and 26 survived to hospital discharge. Serum creatinine was within the reference interval by 72 hours in 22/26 cats (85%). Complications related to the ureteral papilla implantation technique were seen in only 1 cat (3%). Uroabdomen diagnosed on day 3 ultimately resolved over the following 24 hours without surgical intervention. All 31 donor cats survived to discharge. Four donors (13%) experienced mild, transiently increased serum creatinine.
CONCLUSION: Ureteral papilla implantation is a viable technique for neoureterocystostomy in cats undergoing kidney transplantation. Proposed benefits for the recipient include a less technically challenging anastomosis, decreased risk of ureteral obstruction at the anastomosis site, and reduced risk of leakage compared to previous reports. Benefits for recipients should be weighed against risks to donors, including a more complex ureteral harvest, increased surgical time, and potential injury or obstruction of the contralateral ureteral papilla.
PMID:27120269 | DOI:10.1111/vsu.12476
Gallium-Loaded Dissolvable Microfilm Constructs that Provide Sustained Release of Ga(3+) for Management of Biofilms
Adv Healthc Mater. 2015 Dec 30;4(18):2849-59. doi: 10.1002/adhm.201500599. Epub 2015 Nov 24.
The persistence of bacterial biofilms in chronic wounds delays wound healing. Although Ga(3+) can inhibit or kill biofilms, precipitation as Ga(OH)3 has prevented its use as a topical wound treatment. The design of a microfilm construct comprising a polyelectrolyte film that releases noncytotoxic concentrations of Ga(3+) over 20 d and a dissolvable micrometer-thick film of polyvinylalcohol that enables facile transfer onto biomedically important surfaces is reported. By using infrared spectroscopy, it is shown that the density of free carboxylate/carboxylic acid and amine groups within the polyelectrolyte film regulates the capacity of the construct to be loaded with Ga(3+) and that the density of covalent cross-links introduced into the polyelectrolyte film (amide-bonds) controls the release rate of Ga(3+) . Following transfer onto the wound-contact surface of a biologic wound dressing, an optimized construct is demonstrated to release ≈0.7 μg cm(-2) d(-1) of Ga(3+) over 3 weeks, thus continuously replacing Ga(3+) lost to precipitation. The optimized construct inhibits formation of P. aeruginosa (two strains; ATCC 27853 and PA01) biofilms for up to 4 d and causes pre-existing biofilms to disperse. Overall, this study provides designs of polymeric constructs that permit facile modification of the wound-contacting surfaces of dressings and biomaterials to manage biofilms.
PMID:26599466 | PMC:PMC4812672 | DOI:10.1002/adhm.201500599
Inhibition of Pseudomonas aeruginosa biofilm formation on wound dressings
Wound Repair Regen. 2015 Nov-Dec;23(6):842-54. doi: 10.1111/wrr.12365. Epub 2015 Nov 4.
Chronic nonhealing skin wounds often contain bacterial biofilms that prevent normal wound healing and closure and present challenges to the use of conventional wound dressings. We investigated inhibition of Pseudomonas aeruginosa biofilm formation, a common pathogen of chronic skin wounds, on a commercially available biological wound dressing. Building on prior reports, we examined whether the amino acid tryptophan would inhibit P. aeruginosa biofilm formation on the three-dimensional surface of the biological dressing. Bacterial biomass and biofilm polysaccharides were quantified using crystal violet staining or an enzyme linked lectin, respectively. Bacterial cells and biofilm matrix adherent to the wound dressing were visualized through scanning electron microscopy. D-/L-tryptophan inhibited P. aeruginosa biofilm formation on the wound dressing in a dose dependent manner and was not directly cytotoxic to immortalized human keratinocytes although there was some reduction in cellular metabolism or enzymatic activity. More importantly, D-/L-tryptophan did not impair wound healing in a splinted skin wound murine model. Furthermore, wound closure was improved when D-/L-tryptophan treated wound dressing with P. aeruginosa biofilms were compared with untreated dressings. These findings indicate that tryptophan may prove useful for integration into wound dressings to inhibit biofilm formation and promote wound healing.
PMID:26342168 | PMC:PMC4980578 | DOI:10.1111/wrr.12365
Outcome of Donor Cats After Unilateral Nephrectomy as Part of a Clinical Kidney Transplant Program
Vet Surg. 2015 Oct;44(7):914-9. doi: 10.1111/vsu.12362. Epub 2015 Aug 6.
OBJECTIVE: To compare 1) complications between 2 ureteral harvest techniques (ureteral papilla harvest [UPH] and ureteral transection [UT]); 2) to investigate the prevalence of kidney failure in a population of kidney donors; and 3) to evaluate owner satisfaction with commercially sourced cats adopted after kidney donation.
STUDY DESIGN: Retrospective case series.
ANIMALS: Cats (n = 72) that had unilateral nephrectomy for kidney donation.
METHODS: Medical records were reviewed and information on short- and long-term complications and evidence of kidney failure was recorded. Clients were interviewed by telephone to ascertain their satisfaction with the adopted donor cats as pets.
RESULTS: Seventy-two cats had unilateral nephrectomy. Forty-two owners were able to be contacted for survey data. Twenty-eight cats had complete medical records including serum BUN, creatinine, and urine specific gravity. For these 28 cats, mean age at nephrectomy was 1.9 years (median, 1.1 years; range, 0.5-9.3 years) and mean age at follow-up was 6.8 years (median, 5.1 years; range, 1.0-18.7 years). There was no difference in major or minor complication rates between UPH and UT techniques. Kidney failure occurred in 17.8% of cats. All owners were satisfied with the adopted donor cats, which were obtained from commercial facilities.
CONCLUSIONS: UPH is a safe technique in cats being used for kidney donation. Commercially sourced cats make suitable pets after kidney donation. The prevalence of kidney failure in the donor population appears to be higher than that in the general population, but definitive conclusions cannot be made based on this study. Further, prospective study is needed to identify the true prevalence of kidney failure in cats after unilateral nephrectomy.
PMID:26249233 | DOI:10.1111/vsu.12362
Importance of defining experimental conditions in a mouse excisional wound model
Wound Repair Regen. 2015 Mar-Apr;23(2):251-61. doi: 10.1111/wrr.12272.
The murine dorsum dermal excisional wound model has been widely utilized with or without splint application. However, variations in experimental methods create challenges for direct comparison of results provided in the literature and for design of new wound healing studies. Here, we investigated the effects of wound location and size, number of wounds, type of adhesive used for splint fixation on wound healing using splinted or unsplinted dorsum excisional full thickness wound models. One or two 6- or 8-mm full thickness wounds were made with or without splinting in genetically diabetic but heterozygous mice (Dock7(m) + / + Lepr(db) ). Two different adhesives: tissue adhesive and an over the counter cyanoacrylate adhesive (OTCA) "Krazy glue" were used to fix splints. Wound contraction, wound closure, and histopathological parameters including reepithelialization, collagen deposition and inflammation were compared between groups. No significant effect of wound number (1 vs. 2), side (left vs. right and cranial vs. caudal) or size on wound healing was observed. The OTCA group had a significantly higher splint success compared to the tissue adhesive group that resulted in significantly higher reepithelialization and collagen deposition in the OTCA group. Understanding the outcomes and effects of the variables will help investigators choose appropriate experimental conditions for the study purpose and interpret data.
PMID:25703258 | DOI:10.1111/wrr.12272
Polymeric Multilayers that contain Silver Nanoparticles can be Stamped onto Biological Tissues to Provide Antibacterial Activity
Adv Funct Mater. 2011 May 24;21(10):1863-1873. doi: 10.1002/adfm.201002662.
We report the design of polyelectrolyte multilayers (PEMs) that can be prefabricated on an elastomeric stamp and mechanically transferred onto biomedically-relevant soft materials, including medical-grade silicone elastomers (E'~450-1500 kPa; E'-elastic modulus) and the dermis of cadaver-skin (E'~200-600 kPa). Whereas initial attempts to stamp PEMs formed from poly(allylamine hydrochloride) and poly(acrylic acid) resulted in minimal transfer onto soft materials, we report that integration of micrometer-sized beads into the PEMs (thicknesses of 6-160 nm) led to their quantitative transfer within 30 seconds of contact at a pressure of ~196 kPa. To demonstrate the utility of this approach, PEMs were impregnated with a range of loadings of silver-nanoparticles and stamped onto the dermis of human cadaver-skin (a wound-simulant) that was subsequently incubated with bacterial cultures. Skin-dermis stamped with PEMs that released 0.25±0.01 μg cm-2 of silver ions caused a 6 log10 reduction in colony forming units of Staphylococcus epidermidis and Pseudomonas aeruginosa within 12 h. Significantly, this level of silver release is below that which is cytotoxic to NIH 3T3 mouse fibroblast cells. Overall, this study describes a general and facile approach for the functionalization of biomaterial surfaces without subjecting them to potentially deleterious processing conditions.
PMID:25558188 | PMC:PMC4280836 | DOI:10.1002/adfm.201002662
Raman spectroscopy enables noninvasive biochemical characterization and identification of the stage of healing of a wound
Anal Chem. 2014 Apr 15;86(8):3764-72. doi: 10.1021/ac500513t. Epub 2014 Mar 24.
Accurate and rapid assessment of the healing status of a wound in a simple and noninvasive manner would enable clinicians to diagnose wounds in real time and promptly adjust treatments to hasten the resolution of nonhealing wounds. Histologic and biochemical characterization of biopsied wound tissue, which is currently the only reliable method for wound assessment, is invasive, complex to interpret, and slow. Here we demonstrate the use of Raman microspectroscopy coupled with multivariate spectral analysis as a simple, noninvasive method to biochemically characterize healing wounds in mice and to accurately identify different phases of healing of wounds at different time-points. Raman spectra were collected from "splinted" full thickness dermal wounds in mice at 4 time-points (0, 1, 5, and 7 days) corresponding to different phases of wound healing, as verified by histopathology. Spectra were deconvolved using multivariate factor analysis (MFA) into 3 "factor score spectra" (that act as spectral signatures for different stages of healing) that were successfully correlated with spectra of prominent pure wound bed constituents (i.e., collagen, lipids, fibrin, fibronectin, etc.) using non-negative least squares (NNLS) fitting. We show that the factor loadings (weights) of spectra that belonged to wounds at different time-points provide a quantitative measure of wound healing progress in terms of key parameters such as inflammation and granulation. Wounds at similar stages of healing were characterized by clusters of loading values and slowly healing wounds among them were successfully identified as "outliers". Overall, our results demonstrate that Raman spectroscopy can be used as a noninvasive technique to provide insight into the status of normally healing and slow-to-heal wounds and that it may find use as a complementary tool for real-time, in situ biochemical characterization in wound healing studies and clinical diagnosis.
PMID:24559115 | PMC:PMC4004186 | DOI:10.1021/ac500513t
Reduction in wound bioburden using a silver-loaded dissolvable microfilm construct
Adv Healthc Mater. 2014 Jun;3(6):916-28. doi: 10.1002/adhm.201300537. Epub 2014 Feb 12.
Silver is a widely used antimicrobial agent, yet, when impregnated in macroscopic dressings, it stains wounds, can lead to tissue toxicity, and can inhibit healing. Recently, polymeric nanofilms containing silver nanoparticles were reported to exhibit antimicrobial activity at loadings and release rates of silver that are 100× lower than conventional dressings. Here, fabrication of composite microfilm constructs that provide a facile way to transfer the silver-loaded polymeric nanofilms onto wounds in vivo is reported. The construct is fabricated from a silver nanoparticle-loaded polymeric nanofilm that is laminated with a micrometer-thick-soluble film of polyvinylalcohol (PVA). When placed on a moist wound, the PVA dissolves, leaving the silver-loaded nanofilm immobilized on the wound-bed. In vitro, the immobilized nanofilms release <1 μg cm(-2) d(-1) of silver over 30 d from skin dermis and they kill 5 log10 CFUs of Staphylococcus aureus in 24 h. In mice, wounds inoculated with 10(5) CFU S. aureus presented up to 3 log10 less bacterial burden when treated with silver/nanofilms for 3 d, as compared to unmodified wounds. In uncontaminated wounds, silver/nanofilms allow normal and complete wound closure by re-epithelialization. Dissolvable microfilm constructs may overcome key limitations associated with current uses of silver in wound healing.
PMID:24523027 | PMC:PMC4112187 | DOI:10.1002/adhm.201300537
Integration of silver nanoparticle-impregnated polyelectrolyte multilayers into murine-splinted cutaneous wound beds
J Burn Care Res. 2013 Nov-Dec;34(6):e359-67. doi: 10.1097/BCR.0b013e31827e7ef9.
Silver is a commonly used topical antimicrobial. However, technologies to immobilize silver at the wound surface are lacking, while currently available silver-containing wound dressings release excess silver that can be cytotoxic and impair wound healing. We have shown that precise concentrations of silver at lower levels can be immobilized into a wound bed using a polyelectrolyte multilayer attachment technology. These silver nanoparticle-impregnated polyelectrolyte multilayers are noncytotoxic yet bactericidal in vitro, but their effect on wound healing in vivo was previously unknown. The purpose of this study was to determine the effect on wound healing of integrating silver nanoparticle/polyelectrolyte multilayers into the wound bed. A full-thickness, splinted, excisional murine wound healing model was employed in both phenotypically normal mice and spontaneously diabetic mice (healing impaired model). Gross image measurements showed an initial small lag in healing in the silver-treated wounds in diabetic mice, but no difference in time to complete wound closure in either normal or diabetic mice. Histological analysis showed modest differences between silver-treated and control groups on day 9, but no difference between groups at the time of wound closure. We conclude that silver nanoparticle/polyelectrolyte multilayers can be safely integrated into the wound beds of both normal and diabetic mice without delaying wound closure, and with transient histological effects. The results of this study suggest the feasibility of this technology for use as a platform to affect nanoscale wound engineering approaches to microbial prophylaxis or to augment wound healing.
PMID:23511285 | PMC:PMC4609547 | DOI:10.1097/BCR.0b013e31827e7ef9
Tryptophan inhibits biofilm formation by Pseudomonas aeruginosa
Antimicrob Agents Chemother. 2013 Apr;57(4):1921-5. doi: 10.1128/AAC.00007-13. Epub 2013 Jan 14.
Biofilm formation by Pseudomonas aeruginosa has been implicated in the pathology of chronic wounds. Both the d and l isoforms of tryptophan inhibited P. aeruginosa biofilm formation on tissue culture plates, with an equimolar ratio of d and l isoforms producing the greatest inhibitory effect. Addition of d-/l-tryptophan to existing biofilms inhibited further biofilm growth and caused partial biofilm disassembly. Tryptophan significantly increased swimming motility, which may be responsible in part for diminished biofilm formation by P. aeruginosa.
PMID:23318791 | PMC:PMC3623306 | DOI:10.1128/AAC.00007-13
The use of native chemical functional groups presented by wound beds for the covalent attachment of polymeric microcarriers of bioactive factors
Biomaterials. 2013 Jan;34(2):340-52. doi: 10.1016/j.biomaterials.2012.09.055. Epub 2012 Oct 22.
The development of versatile methods that provide spatial and temporal control over the presentation of physical and biochemical cues on wound beds can lead to new therapeutic approaches that expedite wound healing by favorably influencing cellular behaviors. Toward that goal, we report that native chemical functional groups presented by wound beds can be utilized for direct covalent attachment of polymeric microbeads. Specifically, we demonstrated the covalent attachment of maleimide-functionalized and catechol-functionalized microbeads, made of either polystyrene (non-degradable) or poly(lactic-co-glycolic acid) ((PLGA), degradable), to sulfhydryl and amine groups present on porcine dermis used here as an ex vivo model wound bed. A pronounced increase (10-70 fold) in the density and persistence of the covalently reactive microbeads was observed relative to microbeads that adsorb via non-covalent interactions. Complementary characterization of the surface chemistry of the ex vivo wound beds using Raman microspectroscopy provides support for our conclusion that the increased adherence of the maleimide-functionalized beads results from their covalent bond formation with sulfhydryl groups on the wound bed. The attachment of maleimide-functionalized microbeads to wounds created in live wild-type and diabetic mice led to observations of differential immobilization of microbeads on them and were consistent with anticipated differences in the presentation of sulfhydryl groups on the two different wound types. Finally, the incorporation of maleimide-functionalized microbeads in wounds created in wild-type mice did not impair the rate of wound closure relative to an untreated wound. Overall, the results presented in this paper enable a general and facile approach to the engineering of wound beds in which microbeads are covalently immobilized to wound beds. Such immobilized microbeads could be used in future studies to release bioactive factors (e.g., antimicrobial agents or growth factors) and/or introduce topographical cues that promote cell behaviors underlying healing and wound closure.
PMID:23088838 | PMC:PMC3651840 | DOI:10.1016/j.biomaterials.2012.09.055
Polymeric multilayers that localize the release of chlorhexidine from biologic wound dressings
Biomaterials. 2012 Oct;33(28):6783-92. doi: 10.1016/j.biomaterials.2012.05.068. Epub 2012 Jul 9.
Biologic wound dressings contain animal-derived components and are susceptible to high infection rates. To address this issue, we report an approach that permits incorporation of non-toxic levels of the small molecule antiseptic 'chlorhexidine' into biologic dressings. The approach relies on the fabrication of polyelectrolyte multilayer (PEMs) films containing poly(allylaminehydrochloride) (PAH), poly(acrylicacid) (PAA), and chlorhexidine acetate (CX) on elastomeric poly(dimethylsiloxane) (PDMS) sheets. The PEMs (20-100 nm thick) are subsequently stamped onto the wound-contact surface of a synthetic biologic dressing, Biobrane, which contains collagen peptides. Chlorhexidine loading in the PEMs was tailored by tuning the number of (CX/PAA) bilayers deposited, providing burst release of up to 0.98 ± 0.06 μg/cm(2) of CX over 24 h, followed by zero-order release of 0.35 ± 0.04 μg/cm(2)/day for another week. Although the CX concentrations released were below the reported in vitro cytotoxicity limit (5 μg/mL over 24 h) for human dermal fibroblasts, they killed 4 log(10) counts of pathogenic bacteria Staphylococcus aureus in solution. The CX/PEMs could be stamped onto Biobrane with high efficiency to provide CX release kinetics and in vitro antibacterial activity similar to that on PDMS stamps. In a full-thickness 'splinted' dermal wound-model in normal wild-type mice, the CX-functionalized Biobrane showed no decrease in either its adherence to the wound-bed or wound closure rate over 14 days. The murine wounds topically inoculated with ∼10(5) CFU/cm(2) of S. aureus and treated with CX-functionalized Biobrane demonstrated a 3 log(10) decrease in the wound's bacterial burden within 3 days, compared to persistent bacterial colonization found in wounds treated with unmodified Biobrane (n = 10 mice, p < 0.005). Overall, this study presents a promising approach to prevent bacterial colonization in wounds under biologic dressings.
PMID:22784602 | PMC:PMC3404134 | DOI:10.1016/j.biomaterials.2012.05.068
Antibacterial efficacy of silver-impregnated polyelectrolyte multilayers immobilized on a biological dressing in a murine wound infection model
Ann Surg. 2012 Aug;256(2):371-7. doi: 10.1097/SLA.0b013e318256ff99.
OBJECTIVE: To investigate the antibacterial effect of augmenting a biological dressing with polymer films containing silver nanoparticles.
BACKGROUND: Biological dressings, such as Biobrane, are commonly used for treating partial-thickness wounds and burn injuries. Biological dressings have several advantages over traditional wound dressings. However, as many as 19% of wounds treated with Biobrane become infected, and, once infected, the Biobrane must be removed and a traditional dressing approach should be employed. Silver is a commonly used antimicrobial in wound care products, but current technology uses cytotoxic concentrations of silver in these dressings. We have developed a novel and facile technology that allows immobilization of bioactive molecules on the surfaces of soft materials, demonstrated here by augmentation of Biobrane with nanoparticulate silver. Surfaces modified with nanometer-thick polyelectrolyte multilayers (PEMs) impregnated with silver nanoparticles have been shown previously to result in in vitro antibacterial activity against Staphylococcus epidermidis at loadings of silver that are noncytotoxic.
METHODS: We demonstrated that silver-impregnated PEMs can be nondestructively immobilized onto the surface of Biobrane (Biobrane-Ag) and determined the in vitro antibacterial activity of Biobrane-Ag with Staphylococcus aureus. In this study, we used an in vivo wound infection model in mice induced by topical inoculation of S aureus onto full-thickness 6-mm diameter wounds. After 72 hours, bacterial quantification was performed.
RESULTS: Wounds treated with Biobrane-Ag had significantly (P < 0.001) fewer colony-forming units than wounds treated with unmodified Biobrane (more than 4 log10 difference).
CONCLUSIONS: The results of our study indicate that immobilizing silver-impregnated PEMs on the wound-contact surface of Biobrane significantly reduces bacterial bioburden in full-thickness murine skin wounds. Further research will investigate whether this construct can be considered for human use.
PMID:22609841 | PMC:PMC3433034 | DOI:10.1097/SLA.0b013e318256ff99
Additional thoughts on ovariectomy versus ovariohysterectomy
J Am Vet Med Assoc. 2012 Apr 15;240(8):936-7.
Peptides that anneal to natural collagen in vitro and ex vivo
Org Biomol Chem. 2012 Aug 14;10(30):5892-7. doi: 10.1039/c2ob25190f. Epub 2012 Apr 23.
Collagen comprises ¼ of the protein in humans and ¾ of the dry weight of human skin. Here, we implement recent discoveries about the structure and stability of the collagen triple helix to design new chemical modalities that anchor to natural collagen. The key components are collagen mimetic peptides (CMPs) that are incapable of self-assembly into homotrimeric triple helices, but are able to anneal spontaneously to natural collagen. We show that such CMPs containing 4-fluoroproline residues, in particular, bind tightly to mammalian collagen in vitro and to a mouse wound ex vivo. These synthetic peptides, coupled to dyes or growth factors, could herald a new era in assessing or treating wounds.
PMID:22522497 | PMC:PMC3395758 | DOI:10.1039/c2ob25190f
Single paracostal approach to thoracic duct and cisterna chyli: experimental study and case series
Vet Surg. 2011 Oct;40(7):786-94. doi: 10.1111/j.1532-950X.2011.00878.x. Epub 2011 Sep 14.
OBJECTIVE: To-determine the feasibility of a single paracostal abdominal approach for thoracic duct ligation (TDL) and cisterna chyli ablation (CCA) in dogs with chylothorax.
STUDY DESIGN: Observational study and prospective case series.
ANIMALS: Normal dogs (n = 5) and dogs with chylothorax (n = 8).
METHODS: A single paracostal approach with transdiaphragmatic extension for TDL and CCA was developed experimentally (n = 5) and used in 8 clinical cases with subtotal pericardectomy (SPE) performed in 4 dogs. Surgery time, complications, hospitalization time, outcome, and follow-up of clinical cases were recorded.
RESULTS: Exposure of relevant anatomy was excellent; vital lymphatic staining facilitated identification of lymphatic structures. In clinical cases, mean surgery time for TDL + CCA was 136 minutes. Mean hospitalization time was 3.1 days. Seven of 8 cases survived, with 1 dog dying of heart failure shortly after discharge. One dog required a second (left) paracostal approach to ligate 2 more lymphatic vessels. On follow-up (median, 7 months; range, 2-20 months), there was complete resolution of chylothorax in 6 dogs.
CONCLUSIONS: A single paracostal approach provides excellent exposure of cisterna chyli, caudal thoracic duct, and intestinal lymphatics. This approach eliminates the need for repositioning during combined TDL + CCA procedures and avoids an intercostal thoracotomy.
PMID:22380664 | DOI:10.1111/j.1532-950X.2011.00878.x
Prospective comparison of cisterna chyli ablation to pericardectomy for treatment of spontaneously occurring idiopathic chylothorax in the dog
Vet Surg. 2011 Dec;40(8):926-34. doi: 10.1111/j.1532-950X.2011.00902.x. Epub 2011 Sep 16.
OBJECTIVE: Prospective comparison of cisterna chyli ablation (CCA) or pericardectomy (PC) for chylothorax.
STUDY DESIGN: Randomized prospective study. SUBJECT POPULATION: Dogs with idiopathic chylothorax (n= 23).
METHODS: Dogs were treated by thoracic duct ligation (TDL) with either CCA (n = 12) or PC (n = 11). Long-term outcomes, intraoperative central venous pressures (CVPs) and pericardial histology were assessed. Dogs with persistent chylothorax were offered retreatment by the alternative procedure.
RESULTS: Ten (83%) dogs treated by CCA-TDL and 6 (60%) treated by PC-TDL resolved their chylothorax. Retreatment in 4 dogs resulted in resolution in 2 dogs and 2 perioperative deaths. Four dogs developed nonchylous effusions; 2 of which resolved after initiating steroid therapy, 1 of which was unsuccessfully treated by PC, and 1 continues to be managed by thoracocentesis 6.5 years later. CVPs were normal in most dogs and unaffected by PC. On histology, pericardial tissues had extensive external surface fibrosis with mild inflammation. On follow-up (≤ 6.5 years), no recurrence of pleural effusions occurred after initial resolution.
CONCLUSIONS: CCA-TDL appears to offer improved outcomes over historical results with TDL. Results with PC-TDL were more variable for unknown reasons. Venous pressure measurements did not support the hypothesis that venous hypertension was involved in chylothorax or response to therapy in these dogs.
PMID:22091690 | DOI:10.1111/j.1532-950X.2011.00902.x
Effects of renal autograft ischemic storage and reperfusion on intraoperative hemodynamic patterns and plasma renin concentrations in clinically normal cats undergoing renal autotransplantation and contralateral nephrectomy
Am J Vet Res. 2010 Oct;71(10):1220-7. doi: 10.2460/ajvr.71.10.1220.
OBJECTIVE: To evaluate the effect of the duration of cold Ischemia on the renin-angiotensin system during renal transplantation In cats and to define the potential Influence of vasoactive factors in renal tissue following cold ischemic storage versus warm ischemic storage.
ANIMALS: 10 purpose-bred 6-month-old sexually Intact female cats.
PROCEDURES: 10 cats underwent renal autotransplantation after 30 minutes (n=5) or 3 hours (5) of simple, ex vivo cold storage of renal autographs. Following autograft reperfusion, direct hemodynamic variables were measured with a telemetric Implant and samples were collected for plasma renin concentration. Activation of vascular-related genes (renin, endothelin, and angiotensin converting enzyme) relative to 2-hour simple cold or warm ischemia was also evaluated.
RESULTS: No significant difference between groups was detected In any of the hemodynamic variables or postreperfusion plasma renin concentrations measured in this study relative to the duration of cold ischemic storage. There was also no difference between warm- and cold-stored kidneys in the expression of vascular-related genes.
CONCLUSIONS AND CLINICAL RELEVANCE: Prolonged renal Ischemia for clinically relevant durations does not appear to predispose clinically normal cats to altered hemodynamics or high plasma renin concentrations following graft reperfusion. Activation of vasoactive genes does not appear to be Influenced by type of Ischemia over 2 hours.
PMID:20919911 | DOI:10.2460/ajvr.71.10.1220
Surfaces modified with nanometer-thick silver-impregnated polymeric films that kill bacteria but support growth of mammalian cells
Biomaterials. 2010 Feb;31(4):680-90. doi: 10.1016/j.biomaterials.2009.09.092. Epub 2009 Oct 28.
Silver is widely used as a biocidal agent in ointments and wound dressings. However, it has also been associated with tissue toxicity and impaired healing. In vitro characterization has also revealed that typical loadings of silver employed in ointments and dressings (approximately 100 microg/cm(2)) lead to cytotoxicity. In this paper, we report the results of an initial study that sought to determine if localization of carefully controlled loadings of silver nanoparticles within molecularly thin films immobilized on surfaces can lead to antimicrobial activity without inducing cytotoxicity. Polymeric thin films of poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA) were prepared by layer-by-layer deposition and loaded with approximately 0.4 microg/cm(2) to approximately 23.6 microg/cm(2) of silver nanoparticles. Bacterial killing efficiencies of the silver-loaded films were investigated against Staphylococcus epidermidis, a gram-positive bacterium, and it was determined that as little as approximately 0.4 microg/cm(2) of silver in the polymeric films caused a reduction of 6log(10)CFU/mL (99.9999%) bacteria in suspensions incubated in contact with the films (water-borne assays). Significantly, whereas the antibacterial films containing high loadings of silver were found to be toxic to a murine fibroblast cell line (NIH-3T3), the polymeric films containing approximately 0.4 microg/cm(2) of silver were not toxic and allowed attachment, and growth of the mammalian cells. Thus, the results of this study go beyond prior reports by identifying silver-impregnated, polymeric thin films that are compatible with in vitro mammalian cell culture yet exhibit antibacterial activity. These results support the hypothesis that localization of carefully controlled loadings of silver nanoparticles within molecularly thin polymeric films can lead to antimicrobial activity without cytotoxicity. More broadly, this strategy of modifying surfaces with minimal loadings of bioactive molecules indicates the basis of approaches that may permit management of microbial burden in wound beds without impairment of wound healing.
PMID:19864019 | PMC:PMC4824047 | DOI:10.1016/j.biomaterials.2009.09.092
Hypothermic organ preservation by static storage methods: Current status and a view to the future
Cryobiology. 2010 Jul;60(3 Suppl):S13-9. doi: 10.1016/j.cryobiol.2009.06.004. Epub 2009 Jun 16.
The donor organ shortage is the largest problem in transplantation today and is one where organ preservation technology has an important role to play. Static storage of solid organs, especially of the kidney, continues to be the most common method employed for storage and transport of organs from deceased donors. However, the increase in organs obtained from expanded criteria donors and donors with cardiac death provide new challenges in crafting effective preservation methods for the future. This article reviews the current status of static hypothermic storage methods and discusses potential avenues for future exploitation of this technology as the available organ pool is expanded into the more marginal donor categories.
PMID:19538951 | DOI:10.1016/j.cryobiol.2009.06.004