Jack L. Kelly

Enhancing amine terminals in an amine-deprived collagen matrix

Collagen, though widely used as a core biomaterial in many clinical applications, is often limited by its rapid degradability which prevents full exploitation of its potential in vivo. Polyamidoamine (PAMAM) dendrimer, a highly branched macromolecule, possesses versatile multiterminal amine surface groups that enable them to be tethered to collagen molecules and enhance their potential. In this study, we hypothesized that incorporation of PAMAM dendrimer in a collagen matrix through cross-linking will result in a durable, cross-linked collagen biomaterial with free -NH 2 groups available for further multi-biomolecular tethering. The aim of this study was to assess the physicochemical properties of a G1 PAMAM cross-linked collagen matrix and its cellular sustainability in vitro. Different amounts of G1 PAMAM dendrimer (5 or 10 mg) were integrated into bovine-derived collagen matrices through a cross-linking process, mediated by 5 or 25 mM 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) in 5 mM N-hydroxysuccinimide (NHS) and 50 mM 2-morpholinoethane sulfonic acid buffer at pH 5.5. The physicochemical properties of resultant matrices were investigated with scanning electron microscopy (SEM), collagenase degradation assay, differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectra, and ninhydrin assay. Cellular sustainability of the matrices was assessed with Alamar Blue assay and SEM. There was no significant difference in cellular behavior between the treated and nontreated groups. However, the benefit of incorporating PAMAM in the cross-linking reaction was limited when higher concentrations of either agent were used. These results confirm the hypothesis that PAMAM dendrimer can be incorporated in the collagen cross-linking process in order to modulate the properties of the resulting cross-linked collagen biomaterial with free -NH 2 groups available for multi-biomolecular tethering.

Tailoring the properties of cholecyst-derived extracellular matrix using carbodiimide cross-linking.

Modulation of properties of extracellular matrix (ECM) based scaffolds is key for their application in the clinical setting. In the present study, cross-linking was used as a tool for tailoring the properties of cholecyst-derived extracellular matrix (CEM). CEM was cross-linked with varying cross-linking concentrations of N,N-(3-dimethyl aminopropyl)-N′-ethyl carbodiimide (EDC) in the presence of N-hydroxysuccinimide (NHS). Shrink temperature measurements and ATR–FT-IR spectra were used to determine the degree of cross-linking. The effect of cross-linking on degradation was tested using the collagenase assay. Uniaxial tensile properties and the ability to support fibroblasts were also evaluated as a function of cross-linking. Shrink temperature increased from 59°C for non-cross-linked CEM to 78°C for the highest EDC cross-linking concentration, while IR peak area ratios for the free –NH2 group at 3290 cm−1 to that of the amide I band at 1635 cm−1 decreased with increasing EDC cross-linking concentration. Collagenase assay demonstrated that degradation rates for CEM can be tailored. EDC concentrations 0 to 0.0033 mmol/mg CEM were the cross-linking concentration range in which CEM showed varied susceptibility to collagenase degradation. Furthermore, cross-linking concentrations up to 0.1 mmol EDC/mg CEM did not have statistically significant effect on the uniaxial tensile strength, as well as morphology, viability and proliferation of fibroblasts on CEM. In conclusion, the degradation rates of CEM can be tailored using EDC-cross-linking, while maintaining the mechanical properties and the ability of CEM to support cells.

Efficacy of Crosslinking on Tailoring In Vivo Biodegradability of Fibro-Porous Decellularized Extracellular Matrix and Restoration of Native Tissue Structure: A Quantitative Study using Stereology Methods: Tailoring In Vivo Biodegradability of Decellularized ECM

Cholecyst-derived extracellular matrix (CEM) is a fibro-porous decellularized serosal layer of porcine gall-bladder. CEM loses 90% of its weight at 48 h of in vitro collagenase digestion, but takes two months to be completely resorbed in vivo. Carbodiimide (EDC) crosslinking helps tailoring CEMs in vitro collagenase susceptibility. Here, the efficacy of EDC crosslinking on tailoring in vivo biodegradability of CEM is reported. CEM crosslinked with 0.0005 and 0.0033 × 10(3) M of EDC/mg that lose 80% and 0% of their weight respectively to in vitro collagenase digestion, were present even after 180 days in vivo. Quantitative histopathology using stereology methods confirmed our qualitative observation that even a tiny degree of crosslinking can significantly prolong the rate of in vivo degradation and removal of CEM.

An Assessment of Histological Margins and Recurrence of Melanoma In Situ

Background: Melanoma in situ (MIS) accounts for up to 27% of all melanomas. MIS has no metastatic potential and the aim should be to excise the lesion completely with a clear histological margin, although margin clearance remains undefined. We aimed to assess the relation of histological excision margins of MIS to recurrence and progression to invasive disease. Methods: We analyzed all patients with MIS excised by wide local excision or staged excision in our institution over a 5-year period from December 2008 to January 2014 using a prospectively maintained database. Clinicopathologic details included patient demographics, anatomical site of lesion, melanoma subtype, histological excision margin, and recurrence. Results: A total of 410 patients had MIS excised during this time, the majority of which were lentigo maligna subtype (79%). The average histological excision margin was 3.7 mm. The rate of recurrence was 2.2% (9/410), with a median follow-up of 23 months. Lentigo maligna had a similar rate of recurrence to non-lentigo MIS (2.3% vs 1.2%) (P = 0.69). The mean excision margin of those that recurred was 1.9 mm compared with an average of 3.8 mm in those that did not. The rate of recurrence of MIS with histological excision margin ⩽3.00 mm was 3.8% compared with 0.5% in those with a histological margin >3.00 mm (P = 0.03). One case of MIS recurred as invasive disease. Conclusion: At institutions using wide local excision or staged excision for MIS, a histological margin of >3.0 mm is required to achieve a low recurrence rate.

Levels of Evidence in the Plastic Surgery Literature: A Citation Analysis of the Top 50 'Classic' Papers

Background The plastic surgery literature is vast, consisting of a plethora of diverse articles written by a myriad of illustrious authors. Despite this considerable archive of published material, it remains nebulous as to which precise papers have had the greatest impact on our specialty. The aim of this study was to identify the most cited papers in the plastic surgery literature and perform a citation analysis paying particular attention to the evidence levels of the clinical studies. Methods We identified the 50 most cited papers published in the 20 highest impact plastic surgery journals through the Web of Science. The articles were ranked in order of number of citations acquired and level of evidence assessed. Results The top 50 cited papers were published in six different journals between the years 1957 and 2007. Forty-two of the papers in the top 50 were considered as level IV or V evidence. No level I or II evidence was present in the top 50 list. The average level of evidence of the top 50 papers was 4.28. Conclusions In the plastic surgery literature, no positive correlation exists between a high number of citations and a high level of evidence. Anatomical reconstructive challenges tend to be the main focus of plastic surgery rather than pathologic diseases and consequently, papers with lower levels of evidence are relatively more valuable in plastic surgery than many other specialties.

A Barbed Suture Repair For Flexor Tendons: A Novel Technique With No Exposed Barbs

Background: Barbed suture technology has shown promise in flexor tendon repairs, as there is an even distribution of load and the need for a knot is eliminated. We propose that a quick and simple, novel, barbed technique without any exposed barbs on the tendon surface has comparable strength and a smaller cross-sectional area at the repair site than traditional methods of repair. Methods: Forty porcine flexor tendons were randomized to polybutester 4-strand barbed repair or to 4-strand Adelaide monofilament repair. The cross-sectional area was measured before and after repair. Biomechanical testing was carried out and 2-mm gap formation force, ultimate strength of repair, and method of failure were recorded. Results: The mean ultimate strength of the barbed repairs was 54.51 ± 17.9 while that of the Adelaide repairs was 53.17 ± 16.35. The mean 2-mm gap formation force for the barbed group was 44.71 ± 17.86 whereas that of the Adelaide group was 20.25 ± 4.99. The postrepair percentage change in cross-sectional area at the repair site for the Adelaide group and barbed group was 12.0 ± 2.3 and 4.6 ± 2.8, respectively. Conclusions: We demonstrated that a 4-strand knotless, barbed method attained comparable strength to that of the traditional Adelaide repair technique. The barbed method had a significantly reduced cross-sectional area at the repair site compared with the Adelaide group. The 2-mm gap formation force was less in the barbed group than the Adelaide group. Barbed repairs show promise for tendon repairs; this simple method warrants further study in an animal model.

Plastic surgery and the breast: a citation analysis of the literature.

Background: A large proportion of the plastic surgery literature is dedicated to the breast. It is one of the most common topics in our specialty, yet it is unclear which articles have been the most influential. The purpose of this study was to identify the top 100 most-cited articles on breast in the plastic surgery literature and examine the characteristics of each individual article. Methods: Using an electronic database through the Web of Science, we were able to determine the 6 journals that contributed to the 100 most-cited articles on breast in the plastic surgery literature. Results: Each article was examined individually looking at characteristics such as subject matter, article type, country of origin, institution, authorship, and year of publication. Plastic and Reconstructive Surgery contributed the most articles to the top 100 with 81 articles including the most-cited article which has been referenced 673 times to date. The United States produced 73% of the top 100 articles, and the most prolific institution was the University of Texas M. D. Anderson Cancer Center with 15 articles. Conclusions: This study has identified the most influential articles on breast in the plastic surgery literature over the past 68 years and highlighted many important scientific breakthroughs and landmarks that have occurred during this time.

A Guyon's canal ganglion presenting as occupational overuse syndrome: A case report.

Background Occupational overuse syndrome (OOS) can present as Guyons canal syndrome in computer keyboard users. We report a case of Guyons canal syndrome caused by a ganglion in a computer user that was misdiagnosed as OOS. Case presentation A 54-year-old female secretary was referred with a six-month history of right little finger weakness and difficulty with adduction. Prior to her referral, she was diagnosed by her general practitioner and physiotherapist with a right ulnar nerve neuropraxia at the level of the Guyons canal. This was thought to be secondary to computer keyboard use and direct pressure exerted on a wrist support. There was obvious atrophy of the hypothenar eminence and the first dorsal interosseous muscle. Both Froments and Wartenbergs signs were positive. A nerve conduction study revealed that both the abductor digiti minimi and the first dorsal interosseus muscles showed prolonged motor latency. Ulnar conduction across the right elbow was normal. Ulnar sensory amplitude across the right wrist to the fifth digit was reduced while the dorsal cutaneous nerve response was normal. Magnetic resonance imaging of the right wrist showed a ganglion in Guyons canal. Decompression of the Guyons canal was performed and histological examination confirmed a ganglion. The patients symptoms and signs resolved completely at four-month follow-up. Conclusion Clinical history, occupational history and examination alone could potentially lead to misdiagnosis of OOS when a computer user presents with these symptoms and we recommend that nerve conduction or imaging studies be performed.

100 citation classics in the melanoma literature: a bibliometric analysis.

BACKGROUND Modern immunologic therapies targeting genetic mutations have created a renewed interest in melanoma research, and this is reflected in the increasing number of published works. OBJECTIVE The purpose of this study was to identify the top 100 most cited articles in melanoma and to examine the characteristics of each individual article. METHODS Using an electronic database through the Web of Science, we were able to determine the 22 journals that contributed to the 100 most cited articles in melanoma. RESULTS Each article was examined individually looking at characteristics such as subject matter, article type, country of origin, institution, authorship, and year of publication. The New England Journal of Medicine contributed the most articles to the top 100 with 20 articles, whereas the most cited article originated from the Archives of Surgery and has been cited 2,384 times. The United States produced 74% of the top 100 articles, and the most prolific institution was the National Cancer Institute in Maryland with 18 articles. CONCLUSION This study has identified the most significant contributions to melanoma research over the past 63 years and identifies many important scientific breakthroughs and landmarks that have occurred during this time.

Surgical repair of central slip avulsion injuries with Mitek bone anchor--retrospective analysis of a case series.

The purpose of this study is to describe our technique of central slip repair using the Mitek bone anchor and to evaluate the treatment outcome. Eight digits in eight patients were reconstructed using the bone anchor: three little fingers, two middle fingers, two index fingers and one ring finger. There were two immediate and six delayed repairs (range from one day to eight months). Four patients had pre-operative intensive splinting and physiotherapy to restore passive extension of the proximal interphalangeal joint prior to central slip reconstruction. All patients have made good progress since surgery. No patient requires a second procedure and none of the bone anchors have dislodged or loosened. We conclude that the Mitek bone anchor is a reliable technique to achieve soft tissue to bone fixation in central slip avulsion injuries. We recommend that this technique be considered as a treatment option for patients requiring surgical repair.