Altered swelling behavior of femoral cartilage following joint immobilization in a canine model.

Periods of reduced joint loading have been shown to induce changes in the biochemical composition. metabolism and mechanics of articular cartilage. In this study, changes in cartilage swelling behavior were studied following a 4-week period of joint immobilization, using a recently developed osmotic loading technique [J. Biomech, 32 (1999) 401-408]. The magnitude and distribution of swelling strains were measured in cartilage-bone samples equilibrated in physiological and hypotonic saline, relative to a hypertonic reference NaCl solution. Physicochemical parameters (glycosaminoglycan fixed charge density and water volume fraction) were determined in site-matched cartilage samples. The experimental data for swelling strains, fixed charge density and water volume fraction were used with a triphasic mechano-chemical theory [J. Biomech. Eng. 113 (1991) 245-258] to determine the effect of joint immobilization on the tensile modulus of the cartilage solid matrix. Four weeks of immobilization resulted in a significant increase in the magnitude of swelling-induced strains, and a significant decrease in fixed charge density in cartilage, as compared with the contralateral controls. Joint immobilization also resulted in decreases in values for the modulus of cartilage, as compared with the contralateral controls. Our results suggest that 4 weeks of joint immobilization had a significant effect on cartilage mechanical function that may be linked to collagen changes in the cartilage extracellular matrix.     

Progressive slippage after pinning for slipped capital femoral epiphysis

The authors retrospectively reviewed seven cases of progressive slipped capital femoral epiphysis after screw fixation. All seven patients initially presented with chronic symptoms, and five had an acute exacerbation of symptoms with the appearance of an acute-on-chronic slip. Of the other two, one had obvious motion at the proximal femoral physis and the other had increased symptoms but did not have an obvious acute slip radiographically. All underwent percutaneous screw fixation. In four patients a single screw was placed, and in three patients two screws were placed. No patient became symptom-free after surgery. Slip progression was noted on average 5 months after treatment. Radiographs in all patients revealed an increase in slip severity and loss of screw purchase in the femoral neck while fixation in the proximal femoral epiphysis remained secure. One patient had hypothyroidism and another Cushing disease, both diagnosed after the slipped epiphysis. Slips occurring in children with underlying endocrinopathies, and unstable slips in children with a history of antecedent knee or hip pain (commonly called an acute-on-chronic slip) may be susceptible to screw fixation failure. In such patients, close radiographic follow-up, particularly in the presence of continued symptoms, is required to document slip progression and fixation failure as soon as possible.     

嗅鞘细胞移植在大鼠脊髓损伤处能够迁移和促进神经轴突生长吗?

目的：探讨嗅鞘细胞（olfactory ensheathing cells,OEC）移植在大鼠损伤脊髓后是否有独特的迁移和轴突生长导向特性。方法：将表达绿色荧光蛋白基因的OEC注入到C4脊髓损伤大鼠距离损伤部位头端1mm及尾端1mm背柱白质处,注射后1、3、12、24h及3、7、28d灌注固定取材,冰冻切片和免疫组化分析。用骨髓基质细胞和成纤维细胞移植到同样的损伤部位做为对照进行同样的分析。另将OEC注射到距离损伤部位头尾侧1mm处脊髓灰质内、小剂量注射在白质内、在损伤前3d或损伤后9d注射、注射到未损伤脊髓白质中,观察细胞迁移情况。结果：OEC在细胞注射后1h内即形成由注射压力造成的从注射部位向损伤处的被动性延伸带,并且不断地从注射部位向损伤处延伸扩散,在形态学方面好象起到＂桥接＂损伤处的作用。对照组骨髓基质细胞和成纤维细胞注射后也迅速形成细胞＂桥接＂带,并扩散至损伤空腔。将OEC注射到脊髓灰质内或小剂量注射或注射到未损伤的脊髓白质内、在脊髓损伤3d前或9d后注射细胞均没有见到细胞带延伸进入损伤部位。OEC在注射部位、细胞带以及损伤部位有增殖现象。28d后,共焦免疫酶标法证实细胞带取代了脊髓原有星形胶质细胞,但是下行或上行长束轴突没有优先延伸至该细胞带,也没能起到维持皮层脊髓轴突的桥接作用。结论：OEC在植入大鼠损伤脊髓后没有独特的迁移特性,与骨髓基质细胞或成纤维细胞相比没有明显促进轴突生长的作用,也没有支持皮层脊髓轴突在脊髓损伤处形成桥接的作用。     

Functional integrin subunits regulating cell-matrix interactions in the intervertebral disc.

Cellular interactions with the extracellular matrix are key factors regulating cell survival, differentiation, and response to environmental stimuli in cartilagenous tissues. Much is known about the extracellular matrix proteins in the intervertebral disc (IVD) and their variations with region, age, or degenerative state of the tissue. In contrast, little is known of the integrin cell surface receptors that directly bind to and interact with these matrix proteins in the IVD. In almost all tissues, these integrin-mediated cell-matrix interactions are important for transducing environmental cues arising from mechanical stimuli, matrix degradation fragments, and cytokines into intracellular signals. In this study, cells from the nucleus pulposus and anulus fibrosus regions of porcine IVDs were analyzed via flow cytometry to quantify integrin expression levels upon isolation and after monolayer culture. Assays of cell attachment to collagens, fibronectin, and laminin were performed after functional blocking of select integrin subunits to evaluate the role of specific integrins in cell attachment. In situ distribution and co-localization of integrins and laminin were also characterized. Results identify integrin receptors critical for IVD cell interactions with collagens (alpha1beta1) and fibronectin (alpha5beta1). Additionally, dramatic differences in cell-laminin interactions were observed between cells of the nucleus and anulus regions, including differences in alpha6 integrin expression, cell adhesion to laminin, and in situ pericellular environments. These findings suggest laminin-cell interactions may be important and unique to the nucleus pulposus region of the IVD. The results of this study provide new information on functional cell-matrix interactions in tissues of the IVD.     

External pneumatic compression does not increase urokinase plasminogen activator after abdominal surgery

External pneumatic compression (EPC) devices prevent lower extremity deep venous thrombosis (DVT) by reducing stasis. There is a widely held belief that they also enhance endogenous fibrinolysis; however, recent studies of tissue plasminogen activator (the primary activator of fibrinolysis) and plasminogen activator inhibitor-1 (the primary inhibitor of fibrinolysis) failed to confirm this. The hypothesis of this study was that EPC devices increase the level of urokinase plasminogen activator (uPA), a second activator of fibrinolysis. This was a prospective trial in which 44 subjects who underwent major abdominal surgery were randomized to receive unfractionated heparin injections, thigh-length sequential EPC devices, or both for DVT prophylaxis. Prophylaxis was begun immediately before surgical incision and continued until postoperative day 5 or discharge. Venous blood samples were collected from an antecubital vein for measurement of systemic uPA levels and from the common femoral vein for measurement of regional uPA levels. Samples were collected the day before surgery, after induction of anesthesia but before surgical incision, and on postoperative days 1, 3, and 5. uPA levels (ng/mL) were measured with an enzyme-linked immunoassay. Baseline uPA levels (0.41 to 0.56 ng/mL; P >.05, analysis of variance with repeated measures) were similar among the three groups. uPA levels did not change after surgery in systemic or regional blood samples in any group. There were no significant differences in systemic or regional uPA levels in the groups treated with EPC devices relative to those treated with heparin at any time point (P >.05, analysis of variance with repeated measures). Enhancement of fibrinolysis with EPC devices remains unproven; the findings reported here suggest that effective DVT prophylaxis can only be assured when the devices are used in a manner that reduces venous stasis.     

Briefing guide study: preoperative briefing and postoperative debriefing checklists in the Veterans Health Administration medical team training program

Background

The purpose of this study was to examine the outcomes of checklist-driven preoperative briefings and postoperative debriefings during the Veterans Health Administration (VHA) medical team training program.

Methods

A briefing score (1, never started; 2, started then discontinued; 3, maintained on original targeted cases; 4, expanded to other services; 5, briefing all cases, all services) was established at 10.1 ± .3 months after introduction of the checklist. Outcomes included antibiotic and deep venous thrombosis prophylaxis compliance rates before and after use of the checklist.

Results

Antibiotic (97.0% ± .1% vs 92.1% ± 1.5%; P = .01) and deep venous thrombosis (95.7% ± .8% vs 85.1% ± 4.6%; P = .05) prophylaxis compliance rates were higher after initiation of a surgical checklist.

Conclusions

Checklist-driven preoperative briefings and postoperative debriefings are associated with improvements in patient safety for surgical patients.     

Declines in violence and police arrest among female sex workers in Karnataka state,south India,following a comprehensive HIV prevention programme

Introduction

Female sex workers (FSWs) frequently experience violence, harassment and arrest by the police or their clients, but there is little evidence as to the impact that such factors may have on HIV risk or whether community interventions could mitigate this impact.

Methods

As part of the evaluation of the Avahan programme in Karnataka, serial integrated behavioural and biological assessment (IBBA) surveys (four districts) (2005 to 2011) and anonymous polling booth surveys (PBS) (16 districts) (2007 to 2011) were conducted with random samples of FSWs. Logistic regression analysis was used to assess 1) changes in reported violence and arrests over time and 2) associations between violence by non-partners and police arrest and HIV/STI risk and prevalence. Mediation analysis was used to identify mediating factors.

Results

5,792 FSWs participated in the IBBAs and 15,813 participated in the PBS. Over time, there were significant reductions in the percentages of FSWs reporting being raped in the past year (PBS) (30.0% in 2007, 10.0% in 2011, p<0.001), being arrested in the past year [adjusted odds ratio (AOR) 0.57 (0.35, 0.93), p=0.025] and being beaten in the past six months by a non-partner (clients, police, pimps, strangers, rowdies) [AOR 0.69 (0.49, 0.95), p=0.024)] (IBBA). The proportion drinking alcohol (during the past week) also fell significantly (32.5% in 2005, 24.9% in 2008, 16.8% in 2011; p<0.001). Violence by non-partners (being raped in the past year and/or beaten in the past six months) and being arrested in the past year were both strongly associated with HIV infection [AOR 1.59 (1.18, 2.15), p=0.002; AOR 1.91 (1.17, 3.12), p=0.01, respectively]. They were also associated with drinking alcohol (during the past week) [AOR 1.98 (1.54, 2.53), p<0.001; AOR 2.79 (1.93, 4.04), p<0.001, respectively], reduced condom self-efficacy with clients [AOR 0.36 (0.27, 0.47), p<0.001; AOR 0.62 (0.39, 0.98), p=0.039, respectively], symptomatic STI (during the past year) [AOR 2.62 (2.07, 3.30), p<0.001; AOR 2.17 (1.51, 3.13), p<0.001, respectively], gonorrhoea infection [AOR 2.79 (1.51, 5.15), p=0.001; AOR 2.69 (0.96, 7.56), p=0.060, respectively] and syphilis infection [AOR 1.86 (1.04, 3.31), p=0.036; AOR 3.35 (1.78, 6.28), p<0.001, respectively], but not with exposure to peer education, community mobilization or HIV testing uptake. Mediation analysis suggests that alcohol use and STIs may partially mediate the association between violence or arrests and HIV prevalence.

Discussion

Violence by non-partners and arrest are both strongly associated with HIV infection among FSWs. Large-scale, comprehensive HIV prevention programming can reduce violence, arrests and HIV/STI infection among FSWs.     

Prediction of wound healing in human diabetic foot ulcers by diffuse near‐infrared spectroscopy: A pilot study

A human study was conducted in which the efficacy of in vivo diffuse near‐infrared (NIR) spectroscopy was demonstrated in predicting wound healing in diabetic foot ulcers. Sixteen chronic diabetic wounds were followed and assessed for subsurface oxy‐hemoglobin concentration using the NIR device. Weekly measurements were conducted until there was wound closure, limb amputation, or 20 completed visits without healing. Digital photography measured wound size, and the degree of wound contraction was compared with the NIR results. In the 16 patients followed, seven wounds healed, six limbs were amputated, and three wounds remained opened after 20 visits. The initial values in subsurface hemoglobin concentration in all wounds were higher than the nonwound control sites. Healed wounds showed a consistent reduction of hemoglobin concentration several weeks before closure that approached control site values. In wounds that did not heal or resulted in amputation of the limb, the hemoglobin concentration remained elevated. In some cases, these nonhealing wounds appeared to be improving clinically. A negative slope for the rate of change of hemoglobin concentration was indicative of healing across all wounds. In conclusion, evaluation of wounds using NIR may provide an effective measurement of wound healing. NIR spectroscopy can determine wound healing earlier than that visibly assessed by current clinical approaches.     

Albuminuria and Estimated Glomerular Filtration Rate Independently Associate with Acute Kidney Injury

Acute kidney injury (AKI) is increasingly common and a significant contributor to excess death in hospitalized patients. CKD is an established risk factor for AKI; however, the independent graded association of urine albumin excretion with AKI is unknown. We analyzed a prospective cohort of 11,200 participants in the Atherosclerosis Risk in Communities (ARIC) study for the association between baseline urine albumin-to-creatinine ratio and estimated GFR (eGFR) with hospitalizations or death with AKI. The incidence of AKI events was 4.0 per 1000 person-years of follow-up. Using participants with urine albumin-to-creatinine ratios <10 mg/g as a reference, the relative hazards of AKI, adjusted for age, gender, race, cardiovascular risk factors, and categories of eGFR were 1.9 (95% CI, 1.4 to 2.6), 2.2 (95% CI, 1.6 to 3.0), and 4.8 (95% CI, 3.2 to 7.2) for urine albumin-to-creatinine ratio groups of 11 to 29 mg/g, 30 to 299 mg/g, and ≥300 mg/g, respectively. Similarly, the overall adjusted relative hazard of AKI increased with decreasing eGFR. Patterns persisted within subgroups of age, race, and gender. In summary, albuminuria and eGFR have strong, independent associations with incident AKI.It has long been recognized that an episode of acute kidney injury (AKI) can have serious health consequences.^1–4 Even a relatively small degree of renal injury increases a patient''s risk of a prolonged hospital stay, chronic kidney disease (CKD), ESRD, and death.^2,5–10 Over the last 2 decades, the incidence of hospitalized AKI has increased dramatically.^11–14 Precise estimations vary depending on population and method of case identification, but a recent community-based study of AKI estimated the incidence of nondialysis requiring AKI at 522 per 100,000 population per year and dialysis-requiring AKI at 30 per 100,000,¹³ which is well over that of ESRD.¹⁴ This increase in the burden of disease, taken with the associated poor long-term outcomes, has established AKI as a major public health issue.¹⁴Beyond routine supportive care, there exists little established medical therapy for AKI.¹⁵ Many current lines of research are focused on the prevention of AKI. However, few prospective, population-based studies have evaluated the development of AKI.^3,13,16 Hsu et al.,^13,17 along with multiple observational series in various clinical settings, have clearly established older age and CKD as risk factors for AKI.^18–24 Other observed associations with AKI include black race and male gender.^11,18,25 Proteinuria, an established risk factor in the development of cardiovascular disease,^26,27 ESRD,²⁸ and death,²⁹ is less studied in its role in the development of AKI. Hsu and colleagues demonstrated the prospective association of proteinuria with dialysis-requiring AKI; however, the proteinuria classification was binary and based on dipstick measurement.¹⁷ To our knowledge, no study has quantified the independent dose response of albuminuria with AKI hospitalization, including less severe AKI. Our study''s objective was thus to characterize prospectively the association between baseline urine albumin-to-creatinine ratio (UACR) and hospitalizations for AKI, controlling for established and potential risk factors such as CKD, age, and cardiovascular comorbidities.     

Contribution of intraoperative enteroscopy in the management of obscure gastrointestinal bleeding

Obscure gastrointestinal bleeding remains a significant diagnostic challenge. Our aims were (1) to determine the efficacy of intraoperative enteroscopy (IOE) in identifying lesions responsible for obscure gastrointestinal bleeding and (2) to determine the outcome of patients after treatment of these lesions. We retrospectively reviewed all patients who underwent IOE for obscure gastrointestinal bleeding from 1992 to 1998. Patients were divided into those with overt and those with occult gastrointestinal bleeding. Follow-up was complete in 67 patients (96%), with a median of 32 months (range 1 to 91 months). Seventy patients (52 overt and 18 occult) underwent IOE after extensive preoperative evaluation. Median duration of bleeding was 12 months, requiring a median of 14 blood transfusions. Risk factors for bleeding were identified in 46 patients (61 %). A lesion was identified and treated in 52 patients (74%)—39 in the overt group and 13 in the occult group. Lesions identified were vascular (54%), ulcerations (31%), tumors (11%), and small bowel diverticula (4%). Overall, 35 patients (52%) were found to have one or more lesions at IOE that were treated surgically and had no further bleeding. IOE, through a mid-small bowel enterotomy, has low morbidity and is effective in that it identified a treatable lesion in 74% of patients, which led to cure of bleeding in 52%. Presented at the Forty-First Annual Meeting of The Society for Surgery of the Alimentary Tract, San Diego, Calif., May 21–24, 2000, and published as an abstract in Gastroenterology 118(Suppl l):A1057, 2000.