Biomechanical evaluation of 5 fixation devices for proximal interphalangeal joint arthrodesis.

PURPOSE: To determine in a cadaver model which, among 5 fixation methods for proximal interphalangeal (PIP) joint arthrodesis, has the greatest stiffness. METHODS: Thirty-five cadaver digits were randomly assigned to 1 of 5 fixation groups: oblique K-wire with coronal intraosseous wiring, tension-band wire (TBW), dorsal plate, intramedullary linked screw (IMS), and 90/90 wiring (90/90W). Testing was done by applying bending moments to the PIP joint in the sagittal and frontal planes. The force/displacement curves were used to estimate the stiffness of each construct. Ultimate strength was determined by loading to failure in extension. RESULTS: The IMS had significantly higher stiffness than all wiring constructs in all planes of motion and significantly greater stiffness in extension than the dorsal plate. The IMS stiffness exceeded 10 N/mm across all bending directions and showed an ultimate strength of 21 N. The plate demonstrated higher stiffness in radial bending than the oblique K-wire with coronal intraosseous wiring and TBW. There were no differences in stiffness between the IMS and plate in all modes of testing except extension. Load-to-failure testing of the devices showed the IMS device to be significantly stronger than the TBW, 90/90W, and plating constructs. CONCLUSIONS: The IMS resisted larger bending moments than all wiring constructs and showed the greatest ultimate strength when compared with 3 of the tested arthrodesis techniques. The plate was significantly better than 2 of the wiring constructs, but only in radial bending. No differences were found between the, TBW, and 90/90W when compared with each other. CLINICAL RELEVANCE: The stiffness necessary for a successful PIP joint fusion has not been quantified, but according to this study, the IMS was the most favorable biomechanical construct for initial stability.

Leptin affects intestinal epithelial cell turnover in correlation with leptin receptor expression along the villus-crypt axis after massive small bowel resection in a rat.

In this study, we examine the responsiveness of intestinal epithelial cell turnover to leptin (LEP) in correlation with leptin receptor (LEPr) expression along the villus-crypt axis in a rat with short bowel syndrome (SBS). Adult rats underwent either a 75% intestinal resection or a transection. SBS-LEP rats underwent bowel resection and were treated with LEP starting from the fourth postoperative day. Parameters of intestinal adaptation, enterocyte proliferation, and enterocyte apoptosis were determined at sacrifice. RT-PCR technique was used to determine Bax and Bcl-2 gene expression in ileal mucosa. Villus tips, lateral villi, and crypts were separated using laser capture microdissection. LEPr expression for each compartment was assessed by quantitative real-time PCR (Taqman). Treatment with LEP significantly stimulated all parameters of adaptation. LEPr expression in crypts significantly increased in SBS rats (vs Sham rats) and was accompanied by a significant increase in enterocyte proliferation and decreased apoptosis after LEP administration. A significant increase in LEPr expression at the tip of the villus in SBS rats was accompanied by decreased cell apoptosis. In conclusion LEP accelerated enterocyte turnover and stimulated intestinal adaptation. The effect of LEP on enterocyte proliferation and enterocyte apoptosis correlated with receptor expression along the villus-crypt axis.

Effect of oral glutamine on enterocyte turnover during methotrexate-induced mucositis in rats.

BACKGROUND/AIMS: The objective of this study was to evaluate the effects of oral glutamine in preventing intestinal mucosal damage caused by methotrexate (MTX) in rats. METHODS: Male Sprague-Dawley rats were divided into 3 experimental groups: control rats, rats treated intraperitoneally with MTX (MTX rats) and rats treated with oral glutamine in the drinking water (2%) 72 h following intraperitoneal injection of a single dose of MTX (MTX-glutamine rats). Intestinal mucosal damage (Park's injury score), mucosal structural changes, enterocyte proliferation and enterocyte apoptosis were determined 72 h following MTX injection. RT-PCR was used to determine Bax and Bcl-2 mRNA expression. RESULTS: MTX-glutamine rats demonstrated greater jejunal and ileal mucosal weight and mucosal DNA, greater ileal villus height and crypt depth, and a greater index of proliferation in the jejunum and ileum compared to MTX animals. A significant decrease in enterocyte apoptosis in the ileum of MTX-glutamine rats (vs. MTX) was accompanied by decreased Bax and increased Bcl-2 mRNA expression. CONCLUSIONS: Treatment with oral glutamine prevents mucosal injury and improves intestinal recovery following MTX injury in the rat.

Oral insulin enhances cell proliferation and decreases enterocyte apoptosis during methotrexate-induced mucositis in the rat.

OBJECTIVE: Oral insulin (INS) has been shown to protect intestinal epithelial cells from injury caused by ischemia-reperfusion and endotoxemia. In the present study, we tested whether oral insulin can protect gut epithelial cells from methotrexate (MTX)-induced intestinal damage. MATERIALS AND METHODS: Adult male Sprague-Dawley rats were divided into 3 experimental groups. Control rats were treated with normal saline given intraperitoneally (CONTR), MTX rats were treated with a single dose (20 microg/kg) of MTX given intraperitoneally, and MTX-INS rats were treated with oral insulin given in drinking water (1 U/mL) 72 hours after IP injection of a single dose of MTX (similar to MTX rats). Three days after either MTX or saline injection, rats were killed. Intestinal mucosal damage (Park injury score), mucosal structural changes, enterocyte proliferation, and enterocyte apoptosis were measured. Reverse transcription polymerase chain reaction was used to determine the level of bax and bcl-2 mRNA expression. RESULTS: MTX-INS rats demonstrated a greater jejunal and ileal mucosal weight, ileal mucosal DNA, greater jejunal villus height, greater jejunal and ileal crypt depth, greater enterocyte proliferation index in ileum, and lower enterocyte apoptosis in ileum than did MTX-nontreated animals. Treatment with insulin did not change the injury score grade in comparison with MTX animals. A significant decrease in cell apoptosis was observed in MTX-INS rats (vs MTX) and also a decrease in a bax mRNA expression and decrease in a bax/bcl-2 ratio. CONCLUSIONS: In a rat model of MTX-induced mucositis, oral insulin supplementation does not prevent mucosal injury but improves intestinal recovery and enhances enterocyte survival.

Candida Tropicalis Cholangitis in a Patient Without Underlying Malignancy.

Candida tropicalis is a rare cause of acute cholangitis, predominantly seen in patients with underlying hematological malignancies. Here, we describe a case of acute cholangitis caused by mixed organisms (Candida tropicalis, Candida albicans, and Enterococcus durans) without a known risk factor.

In vitro kinematics of the proximal interphalangeal joint in the finger after progressive disruption of the main supporting structures.

BACKGROUND: Fractures and dislocations of the proximal interphalangeal (PIP) joint of the fingers are among the most common causes of injury in the hand. Objective assessment of the kinematic alterations occurring when the supporting structures are disrupted is critical to obtain a more accurate indication of joint stability. METHODS: An in vitro cadaver model of the hand was used to evaluate the kinematics of the PIP joint in the finger during active unrestrained flexion and extension. The kinematics of the PIP joint following progressive disruption of the main supporting structures was measured using an optical tracking system and compared with those in the intact joint. RESULTS: Flexion of the intact PIP joint was associated with joint compression, volar displacement, and rotational movements. Release of the main soft-tissue stabilizers and 30 % of volar lip disruption resulted in substantial alteration of several kinematic variables. The normalized maximum dorsal/volar translation was 0.1 ± 1.3 % in the intact group and 14.4 ± 11.3 % in the injured joint. CONCLUSIONS: In the intact PIP joint, rotations and translation are strongly coupled to the amount of joint flexion. Gross instability of the PIP joint occurs when disruption of the collateral ligaments and volar plate is accompanied by resection of at least 30 % of volar lip of the middle phalanx. Collateral ligament injuries, volar plate injuries alone, and fractures at the volar base of the middle phalanx that involve less than 30 % of the articular surface are unlikely to result in gross instability and may be managed effectively with non-operative treatments.

Sequelae of foreign bodies in the wrist and hand.

BACKGROUND: Penetrating injuries to the hand are a common occurrence in the emergency room, and embedment of foreign bodies is suspected in many of these cases. The existing literature offers little information on retained foreign bodies. The aim of this study was to identify characteristics, determine prevalence, and observe outcomes for retained foreign bodies in the wrist and hand. METHODS: Four hundred thirty-seven consecutive hand and wrist radiographs in 437 patients from the emergency department of a level 1 trauma center were reviewed for the presence of retained foreign bodies. Location, size, number, and type of foreign body were recorded. Patient demographics, mechanism of injury, associated injuries, and treatment were obtained from medical records. All subsequent hospital and outpatient encounters were reviewed. Follow-up period was 18 months (range, 1-40). RESULTS: Of 437 cases, 65 patients (15 %) had at least one retained foreign body. Nineteen patients underwent removal of foreign body at initial presentation. The average size of foreign bodies removed was 6 mm, compared to 3 mm for those retained. Of 46 patients where the foreign body was left in situ, two (4 %) developed symptoms directly related to the retained foreign body. One of these patients underwent removal. CONCLUSIONS: This study supports the safe removal of foreign bodies which are easily accessible or when part of a broader procedure to repair injured structures. Otherwise, we advocate expectant management for all other patients, as the likelihood of persistent symptoms is low and only 2 % of retained foreign bodies required removal later.

Transforming growth factor-alpha stimulates enterocyte proliferation and accelerates intestinal recovery following methotrexate-induced intestinal mucositis in a rat and a cell culture model.

PURPOSE: Recent evidence suggests that transforming growth factor-alpha (TGF-alpha) enhances enterocyte proliferation and exerts a gut trophic effect. The purpose of the present study was to evaluate the effect of TGF-alpha on enterocyte proliferation and intestinal recovery following methotrexate (MTX)-induced intestinal mucositis in rats and in Caco-2 cells. METHODS: Nonpretreated Caco-2 cells and those pretreated with MTX were incubated with increasing concentrations of TGF-alpha. Cell proliferation was determined by FACS cytometry. Adult rats were divided into three groups: control rats treated with vehicle, MTX rats treated with one dose (20 microg/kg) of MTX given intraperitoneally, and MTX-TGF-alpha rats treated with one dose of MTX followed by two doses of TGF-alpha (75 microg/kg a day). Three days after MTX injection, rats were sacrificed. Intestinal mucosal damage (Park's score), mucosal structural changes, and enterocyte proliferation were measured at sacrifice. Western blotting was used to determine the level of extracellular signal-related kinase (ERK) protein, a marker of cell proliferation. A nonparametric Kruskal-Wallis ANOVA test was used for statistical analysis with P value less than 0.05 considered statistically significant. RESULTS: The in vitro experiment demonstrated that treatment with TGF-alpha of Caco-2 cells resulted in a significant stimulation of cell proliferation in a dose-dependent manner. The in vivo experiment showed that treatment with TGF-alpha resulted in a significant increase in bowel and mucosal weight, DNA and protein content in jejunum and ileum, villus height in jejunum and ileum, crypt depth in ileum, and increased cell proliferation in jejunum and ileum compared to the MTX group. MTX-TGF-alpha rats also had a significantly lower intestinal injury score in ileum when compared to MTX animals. The increase in levels of cell proliferation in MTX-TGF-alpha rats corresponded with the increase in ERK protein levels in intestinal mucosa. CONCLUSION: Treatment with TGF-alpha prevents mucosal injury, enhances ERK-induced enterocyte proliferation, and improves intestinal recovery following MTX-induced intestinal mucositis in rats. These findings correlated with the observation that TGF-alpha also caused a significant stimulation of cell proliferation in a Caco-2 cell culture model treated with MTX. These observations may have significant implications for the treatment of patients on chemotherapy who develop severe mucositis.