Cross-Linked Cholecyst-Derived Extracellular Matrix for Abdominal Wall Repair.

Abdominal wall repair frequently utilizes either nondegradable or biodegradable meshes, which are found to stimulate undesirable biological tissue responses or which possess suboptimal degradation rate. In this study, a biologic mesh prototype made from carbodiimide cross-linked cholecyst-derived extracellular matrix (EDCxCEM) was compared with small intestinal submucosa (Surgisis®), cross-linked bovine pericardium (Peri-Guard®), and polypropylene (Prolene®) meshes in an in vivo rabbit model. The macroscopic appearance and stereological parameters of the meshes were evaluated. Tailoring the degradation of the EDCxCEM mesh prevents untimely degradation, while allowing cellular infiltration and mesh remodeling to take place in a slower but predictable manner. The results suggest that the cross-linked biodegradable cholecyst-derived biologic mesh results in no seroma formation, low adhesion, and moderate stretching of the mesh. In contrast to Surgisis, Peri-Guard, and Prolene meshes, the EDCxCEM mesh showed a statistically significant increase in the volume fraction (Vv) of collagen (from 34% to 52.1%) in the central fibrous tissue region at both day 28 and 56. The statistically high length density (Lv), of blood vessels for the EDCxCEM mesh at 28 days was reflected also by the higher cellular activity (high Vv of fibroblast and moderate Vv of nuclei) indicating remodeling of this region in the vicinity of a slowly degrading EDCxCEM mesh. The lack of mesh area stretching/shrinkage in the EDCxCEM mesh showed that the remodeled tissue was adequate to prevent hernia formation. The stereo-histological assays suggest that the EDCxCEM delayed degradation profile supports host wound healing processes including collagen formation, cellular infiltration, and angiogenesis. The use of cross-linked CEM for abdominal wall repair is promising.

A clinically relevant in vivo model for the assessment of scaffold efficacy in abdominal wall reconstruction.

An animal model that allows for assessment of the degree of stretching or contraction of the implant area and the in vivo degradation properties of biological meshes is required to evaluate their performance in vivo. Adult New Zealand rabbits underwent full thickness subtotal unilateral rectus abdominis muscle excision and were reconstructed with the non-biodegradable Peri-Guard®, Prolene® or biodegradable Surgisis® meshes. Following 8 weeks of recovery, the anterior abdominal wall tissue samples were collected for measurement of the implant dimensions. The Peri-Guard and Prolene meshes showed a slight and obvious shrinkage, respectively, whereas the Surgisis mesh showed stretching, resulting in hernia formation. Surgisis meshes showed in vivo biodegradation and increased collagen formation. This surgical rabbit model for abdominal wall defects is advantageous for evaluating the in vivo behaviour of surgical meshes. Implant area stretching and shrinkage were detected corresponding to mesh properties, and histological analysis and stereological methods supported these findings.

Analysis of features associated with equivocal diagnosis and diagnostic discordance of Spitz naevi over an 18-year period.

BACKGROUND: Distinguishing Spitz naevi from malignant melanoma can pose diagnostic dilemmas and atypical subtypes present particular challenges to both clinicians and pathologists. OBJECTIVES: We aimed to review our institutional experience of Spitz naevi, to characterise demographics and analyse the clinical and histological features associated with difficult/equivocal diagnosis of such lesions. Additionally we evaluated discordant cases following expert opinion at a second institution. MATERIALS & METHODS: Data was retrospectively analysed on all cases of Spitz naevi treated over an 18-year period (1991-2009). Equivocal cases, (where a diagnosis of classical Spitz naevi could not be confidently made) were identified. The original/provisional diagnosis and second histopathological opinions were compared. RESULTS: 148 cases were identified 112 lesions were classical Spitz naevi. 36 lesions (24.3%) posed diagnostic difficulty (equivocal cases). These equivocal cases tended to occur in the lower limbs, have brown pigmentation, be smaller in size (<6mm) and occur in older (>24 years) patients. Clinical sub-types and gender were not associated with equivocal cases. Of the 36 equivocal cases, the second opinion in 23 cases (63.9%) concurred with the original diagnosis. Of the remaining 13 cases (discordant cases), 10 cases that were originally deemed malignant were reported as benign after the second opinion. Two benign lesions were reclassified as malignant. CONCLUSION: A firm histological diagnosis of Spitz naevi cannot be made with certainty in nearly a quarter of cases. Thus, additional external analysis for a second opinion should be sought for these equivocal cases.

Skin thickness of the anterior, anteromedial, and anterolateral thigh: a cadaveric study for split-skin graft donor sites.

BACKGROUND: The depth of graft harvest and the residual dermis available for reepithelization primarily influence the healing of split-skin graft donor sites. When the thigh region is chosen, the authors hypothesize based on thickness measurements that the anterolateral region is the optimal donor site. METHODS: Full-thickness skin specimens were sampled from the anteromedial, anterior, and anterolateral regions of human cadavers. Skin specimens were cut perpendicularly with a custom-made precision apparatus to avoid the overestimation of thickness measurements. The combined epidermal and dermal thicknesses (overall skin thickness) were measured using a digital calliper. The specimens were histologically stained to visualize their basement membrane, and microscopy images were captured. Since the epidermal thickness varies across the specimen, a stereological method was used to eliminate observer bias. RESULTS: Epidermal thickness represented 2.5% to 9.9% of the overall skin thickness. There was a significant difference in epidermal thickness from one region to another (P<0.05). The anterolateral thigh region had the most consistent and highest mean epidermal thickness (60±3.2 µm). We observed that overall skin thickness increased laterally from the anteromedial region to the anterior and anterolateral regions of the thigh. The overall skin thickness measured 1,032±435 µm in the anteromedial region compared to 1,220±257 µm in the anterolateral region. CONCLUSIONS: Based on skin thickness measurements, the anterolateral thigh had the thickest epidermal and dermal layers. We suggest that the anterolateral thigh region is the optimal donor site for split-skin graft harvests from the thigh.

A case of recurring multifocal giant cell tumour of the tendon sheath in a child.

Giant cell tumour of the tendon sheath is rare in children. We present an unusual case of a recurring multifocal giant cell tumour of the tendon sheath in the hand and wrist of an 11-year-old boy. We are not aware of any similar report in the literature.

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.

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 CEM's 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.

Novel use of hand fracture fixation plates in the surgical stabilisation of flail chest.

Plastic surgeons specialize in working closely with other surgical colleagues to help solve clinical problems. In this case, we performed surgical stabilisation of a large flail chest fragment in conjunction with the cardiothoracic surgical team, using the mini-plating set more commonly used for hand fracture fixation. The use of this fixation system for flail chest has not previously been described, but offers advantages over other reported methods, primarily by dispensing with the need for an extensive thoracotomy incision and by providing robust stabilisation without the presence of prominent hardware.

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 degrees C for non-cross-linked CEM to 78 degrees C for the highest EDC cross-linking concentration, while IR peak area ratios for the free -NH(2) 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.

Illness representations in patients with hand injury.

PURPOSE: Differences in illness perception about hand injury may partly explain the variation in health behaviours such as adherence to post-operative therapy, coping strategy, emotional response and eventual clinical outcome. This study examined the illness perception of patients with hand injuries in the acute trauma setting. METHODS: The disability and severity of injury were assessed using the Disability of the Arm, Shoulder and Hand (DASH) questionnaire and the Hand Injury Severity Score (HISS). The revised Illness Perception Questionnaire (IPQ-R) was used to explore patients' illness beliefs and perception on hand injury. RESULTS: Fifty seven patients were recruited over the 2 month period. The IPQ-R showed good internal reliability (Cronbach's alpha, 0.68-0.86). There was no correlation between the DASH or HISS scores and the various components of the IPQ-R scores, suggesting that illness perceptions were not influenced by the recent trauma experience. Patients with dominant hand injuries and females reported significantly higher subjective disability. Younger patients believed their injury would last for a limited duration but reported a significantly higher number of related symptoms. Overall, the cohort was optimistic about their treatment and duration of recovery (high treatment control score and low time line score). Beliefs of negative consequences, chronic/cyclical duration and low illness coherence were linked with negative emotional response. High illness identity was associated with perception of pessimistic outcome (high consequences score) and negative emotional response. CONCLUSIONS: The lack of correlations suggests that illness perceptions of patients do not necessarily relate to the recent trauma experience or the severity of their hand injury. Patients in this cohort were optimistic about treatment and their recovery. There was some evidence to suggest that patients with severe injury were over-optimistic about recovery. These findings suggest that there could be a role for psychological intervention in hand injury.

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.

Buttressing staples with cholecyst-derived extracellular matrix (CEM) reinforces staple lines in an ex vivo peristaltic inflation model.

BACKGROUND: Staple line leakage and bleeding are the most common problems associated with the use of surgical staplers for gastrointestinal resection and anastomotic procedures. These complications can be reduced by reinforcing the staple lines with buttressing materials. The current study reports the potential use of cholecyst-derived extracellular matrix (CEM) in non-crosslinked (NCEM) and crosslinked (XCEM) forms, and compares their mechanical performance with clinically available buttress materials [small intestinal submucosa (SIS) and bovine pericardium (BP)] in an ex vivo small intestine model. METHODS: Three crosslinked CEM variants (XCEM0005, XCEM001, and XCEM0033) with different degree of crosslinking were produced. An ex vivo peristaltic inflation model was established. Porcine small intestine segments were stapled on one end, using buttressed or non-buttressed surgical staplers. The opened, non-stapled ends were connected to a peristaltic pump and pressure transducer and sealed. The staple lines were then exposed to increased intraluminal pressure in a peristaltic manner. Both the leak and burst pressures of the test specimens were recorded. RESULTS: The leak pressures observed for non-crosslinked NCEM (137.8 +/- 22.3 mmHg), crosslinked XCEM0005 (109.1 +/- 14.1 mmHg), XCEM001 (150.1 +/- 16.0 mmHg), XCEM0033 (98.8 +/- 10.5 mmHg) reinforced staple lines were significantly higher when compared to non-buttressed control (28.3 +/- 10.8 mmHg) and SIS (one and four layers) (62.6 +/- 11.8 and 57.6 +/- 12.3 mmHg, respectively) buttressed staple lines. NCEM and XCEM were comparable to that observed for BP buttressed staple lines (138.8 +/- 3.6 mmHg). Only specimens with reinforced staple lines were able to achieve high intraluminal pressures (ruptured at the intestinal mesentery), indicating that buttress reinforcements were able to withstand pressure higher than that of natural tissue (physiological failure). CONCLUSIONS: These findings suggest that the use of CEM and XCEM as buttressing materials is associated with reinforced staple lines and increased leak pressures when compared to non-buttressed staple lines. CEM and XCEM were found to perform comparably with clinically available buttress materials in this ex vivo model.

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

BACKGROUND: Occupational overuse syndrome (OOS) can present as Guyon's canal syndrome in computer keyboard users. We report a case of Guyon's 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 Guyon's 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 Froment's and Wartenberg's 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 Guyon's canal. Decompression of the Guyon's canal was performed and histological examination confirmed a ganglion. The patient's 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.

Amine functionalization of cholecyst-derived extracellular matrix with generation 1 PAMAM dendrimer.

A method to functionalize cholecyst-derived extracellular matrix (CEM) with free amine groups was established in an attempt to improve its potential for tethering of bioactive molecules. CEM was incorporated with Generation-1 polyamidoamine (G1 PAMAM) dendrimer by using N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide and N-hydroxysuccinimide cross-linking system. The nature of incorporation of PAMAM dendrimer was evaluated using shrink temperature measurements, Fourier transform infrared (FTIR) assessment, ninhydrin assay, and swellability. The effects of PAMAM incorporation on mechanical and degradation properties of CEM were evaluated using a uniaxial mechanical test and collagenase degradation assay, respectively. Ninhydrin assay and FTIR assessment confirmed the presence of increasing free amine groups with increasing quantity of PAMAM in dendrimer-incorporated CEM (DENCEM) scaffolds. The amount of dendrimer used was found to be critical in controlling scaffold degradation, shrink temperature, and free amine content. Cell culture studies showed that fibroblasts seeded on DENCEM maintained their metabolic activity and ability to proliferate in vitro. In addition, fluorescence cell staining and scanning electron microscopy analysis of cell-seeded DENCEM showed preservation of normal fibroblast morphology and phenotype.

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.

Contact with existing adipose tissue is inductive for adipogenesis in matrigel.

The effect of adipose tissue on inductive adipogenesis within Matrigel (BD Biosciences) was assessed by using a murine chamber model containing a vascular pedicle. Three-chamber configurations that varied in the access to an adipose tissue source were used, including sealed- and open-chamber groups that had no access and limited access, respectively, to the surrounding adipose tissue, and a sealed-chamber group in which adipose tissue was placed as an autograft. All groups showed neovascularization, but varied in the amount of adipogenesis seen in direct relation to their access to preexisting adipose tissue: open chambers showed strong adipogenesis, whereas the sealed chambers had little or no adipose tissue; adipogenesis was restored in the autograft chamber group that contained 2- to 5-mg fat autografts. These showed significantly more adipogenesis than the sealed chambers with no autograft ( p < 0.01). Autografts with 1mg of fat were capable of producing adipogenesis but did so less consistently than the larger autografts. These findings have important implications for adipose tissue engineering strategies and for understanding de novo production of adipose tissue.