The effect of prior leaning on human postural responses

This study examines how human postural responses are altered by leaning about the ankles to five different initial stance positions prior to anterior or posterior horizontal translations of the support surface. When subjects leaned in the same direction as the translation-induced sway, postural strategies changed to use of less ankle torque and more horizontal shear forces at the surface to return to equilibrium. This change in strategy was associated with reduced and delayed activation of the stretched ankle muscles and an increased activation of proximal muscles producing rapid hip flexions or extensions. The changes in ankle muscle activation strength and latencies cannot be predicted based on simple stretch or load reflexes, but match predictions from computational, biomechanical models of human stance co-ordination^1–4.     

输血传播西尼罗病毒

西尼罗病毒(WNV)属黄病毒科黄热病毒属。黄热病毒属的其它成员包括登革热病毒、扁虱热传播性脑炎、黄热病,日本脑炎和圣·路易斯大脑炎病毒。1937年Smithburn及其同事首先从白尼罗河源头乌干达北部的西尼罗河地区一例37岁妇女的血液中分离出WNV,按照当时的情况,新分离的虫媒病毒的命名以获得该病毒的地理名称命名。耶例妇女参与了昏睡病监视项目,并且在抽血的当天有38.1℃的发热,分离出的病毒在恒河猴大脑内和鼻内接种以后导致发热和脑炎(但是当给予静脉注射时只有发烧)以及诱导了免疫。非洲绿猴脑内接种该病毒没有使其患上脑炎,仅有发热,感染该病毒后做鼠生物实验,发现3只恒河猴中有2只血液中含有该病毒达9天。     

Endoscopic retrograde cholangiopancreatography after pancreaticoduodenectomy for benign and malignant disease: indications and technical outcomes

BACKGROUND AND STUDY AIMS: Patients undergoing pancreaticoduodenectomy develop postoperative complications related to surgery and their disease. Very little data are available on the role or success of endoscopic retrograde cholangiopancreatography (ERCP) in such patients. The aim of this study was to evaluate the indications and role of diagnostic and therapeutic ERCP after pancreaticoduodenectomy for both benign and malignant disease. PATIENTS AND METHODS: This study was a 10-year (1990 - 2000) single institution retrospective review of all ERCPs performed on patients who had undergone pancreaticoduodenectomy surgery. Indications for the ERCP and technical procedural success were studied. RESULTS: 29 patients with a pancreaticoduodenectomy underwent 56 ERCPs. Reasons for surgery were neoplasia and chronic pancreatitis. Indications for ERCP included evaluation of jaundice and pain. Technical success related to the clinical indication (jaundice 69 %, pain 54 %). CONCLUSION: ERCP plays an important role in the management of postpancreatic surgery problems including biliary and anastomotic strictures, and should be the modality of choice. However, surgical technique may make the afferent limb inaccessible, and the ductal anastomosis difficult to identify in patients with some types of pancreaticoduodenectomy. Closer collaboration between surgeon and endoscopist may allow alterations in surgical technique to improve postoperative ERCP success.     

Role of free protein S and C4b binding protein in regulating the coagulant response to Escherichia coli

Previous studies showed that infusion of C4b-binding protein with sublethal Escherichia coli (E. coli) in the primate produced a consumptive coagulopathy followed by microvascular thrombosis and renal failure. The first objective of this study was to characterize the pathophysiology and mechanism of this phenomena following infusion of both these agents with emphasis on defining the role of free protein S. The second objective was to examine the relevance of this model to the hemolytic uremic syndrome. Infusion of C4b-binding protein alone reduced free protein S and decreased platelet concentration to 20% of baseline, whereas infusion of the C4b-binding protein/protein S complex did not. There was no activation of other inflammatory or coagulant factors. Infusion of sublethal E coli alone produced a transient inflammatory response with no reduction of free protein S. However, coinfusion of C4b-binding protein with sublethal E coli reduced free protein S and produced a thrombocytopenia, anemia, and a microvascular thrombotic response, whereas infusion of the C4b-binding protein/protein S complex with sublethal E coli did not. Studies comparing the effects of neutralizing (S-163) and nonneutralizing (S- 145) antibodies with protein S coinfused with sublethal E coli produced similar contrasting results. Therefore, we concluded that neutralization of free protein S, and not some other property of C4b- binding protein influenced by protein S, accounted for this microvascular thrombotic response. This response is similar to the hemolytic uremic syndrome characterized by thrombocytopenia, anemia, shistocytosis, and renal glomerular thrombosis with uremia. Comparison of the respective renal histopathologic appearance supports this conclusion. This raises the possibility that inhibition of protein S activity (possibly by one of the forms of C4b-binding proteins) might be one of the factors contributing to microvascular thrombotic disorder, such as the hemolytic uremic syndrome.     

A multicenter study of viral hepatitis in a United States hemophilic population

Hemophilia A and B patients seen at nine US regional treatment centers were tested for serologic markers of hepatitis B virus (HBV), hepatitis C virus (HCV), and hepatitis delta virus (HDV) during 1987 and 1988. Because human immunodeficiency virus (HIV) infection, a potentially confounding variable, was present in 53% of the group, the population was divided by HIV status for analysis purposes. In the HIV-positive group (N = 382), less than 1% had not been infected with HBV, HCV, or HDV, whereas 75% had evidence of infection with HBV and 98% with HCV. HBsAg, a marker of active HBV infection, was present in 12% of subjects; 96% of these were HCV positive. Anti-HDV was detected in 35 subjects (9.1%); all were anti-HBc positive. Ten of the 35 (29%) also were positive for IgM anti-HDV, indicating current infection. All 10 were HBsAg positive and 7 of the 9 tested were HDV RNA positive. Severe/moderate hemophilia B patients were more likely to have experienced an HBV infection and to be anti-HDV positive than were similar hemophilia A patients (22% v 8%, P < .05). In the HIV-negative group (N = 345), the subjects were younger and had less severe hemophilia than the HIV-positive patients. No evidence of HBV, HCV, or HDV infection was found in 18%, whereas 33% had experienced HBV infection and 79% were anti-HCV positive. Within this group, 4% were HBsAg positive. All 13 subjects with anti-HDV (4% of the HIV-negative group) also possessed anti-HBc. One (7.7%) was IgM anti-HDV positive and the serum from another contained HDV RNA. Both of these individuals were HBsAg positive. As in the HIV-positive group, severe/moderate hemophilia B patients were more likely to be HBV and HDV positive than were hemophilia A patients (9% v 3%, P < .05). A prevalence study of viral hepatitis in a large US hemophilic population showed that active infection with HCV is common, occurring in 89% of all study patients regardless of HIV status. Evidence of active HBV infection was found in 8%; 19% of these were actively infected with HDV. HDV was more common in hemophilia B patients after controlling for disease severity.     

Dusart syndrome: a new concept of the relationship between fibrin clot architecture and fibrin clot degradability: hypofibrinolysis related to an abnormal clot structure

Fibrinogen Dusart is a congenital dysfibrinogenemia (A-alpha 554 Arginine-->Cysteine) associated with severe thrombotic disorder, high incidence of thrombotic embolism, and abnormal fibrin polymerization. This thrombotic disorder was attributed to an abnormal clot thrombolysis with reduced plasminogen binding to fibrin and defective plasminogen activation by tissue plasminogen activator. The purpose of this work was to assess whether clot architecture could be involved in the thromboresistance of the fibrin Dusart and the high incidence of embolism. An important change in Dusart fibrin clot structure was identified with dramatic decrease of gel porosity (Ks), fiber diameters (d), and fiber mass-length ratios (mu) derived from permeation analysis. In addition, rigidity of the Dusart clot was found to be greatly increased compared with normal fibrin. We provide evidence that both thrombolysis resistance and abnormal rigidity of the fibrin Dusart are related to this abnormal architecture, which impairs the access of fibrinolytic enzymes to the fibrin and which is responsible for a brittle clot that breaks easily, resulting in a high incidence of embolism. Indeed, when restoring a normal clot structure by adding dextran 40 (30 mg/mL) before coagulation, clot thrombolysis and clot rigidity recovered normal values. This effect was found to be dose- dependent. We conclude that clot architecture is crucial for the propensity of blood clot to be degraded and that abnormal clot structure can be highly thrombogenic in vivo. The alpha-C domains of fibrinogen are determinant in fibrin clot structure.     

Recurrent thrombotic thrombocytopenic purpura (TTP) as a complication of acute relapsing pancreatitis

Pancreatitis is a known complication of thrombotic thrombocytopenic purpura (TTP) found in approximately 2% of cases. The development of TTP as a clinical sequelae of acute pancreatitis has also been reported, including one patient with chronic pancreatitis who developed TTP on two occasions following acute exacerbations of pancreatitis. We describe a case in which multiple distinct episodes of TTP have followed the clinical and laboratory demonstration of acute pancreatitis in the same patient. Supportive care of the patient's pancreatitis and plasmapheresis in each case resulted in clinical improvement and resolution of TTP. While the pathophysiologic mechanism explaining this association remains unclear, the recurrence of TTP associated with the "rechallenge" of relapsing episodes of pancreatitis in our patient suggests that a cause-and-effect relationship does exist.     

Juvenile polyps with cachexia. Report of an infant and comparison with Cronkhite-Canada syndrome in adults

Juvenile polyps occur in adults and infants; where multiple, they may be complicated by progressive cachexia with hypoalbuminemia and electrolyte depletion. We report a fatal case of multiple juvenile polyposis with cachexia, alopecia, and megalocephaly presenting in a 9-month-old infant, and review 2 additional cases in infancy. A similar syndrome in adults had been described by Cronkhite and Canada, with intestinal polyposis, nail dystrophy, hyperpigmentation, and alopecia. Histological examination of a polyp from one case of Cronkhite-Canada syndrome suggests a juvenile rather than adenomatous pathology. Multiple juvenile polyps can cause devastating enteropathy and cachexia.     

Follow-up studies of multicystic dysplastic kidneys

Thirty cases of multicystic dysplastic kidney (MCDK) were diagnosed over 11 years. Nine patients underwent nephrectomy: three for increasing kidney size (classic MCDK) and six because of an inconclusive diagnosis (hydronephrotic MCDK). Of the remaining 21 patients, 19 were followed up for a mean of 33.5 months (range, 2-101 months). Follow-up ultrasound examinations revealed that 16 kidneys did not change in size, one decreased in size after cyst puncture, and two disappeared (one after cyst puncture). This series included one case of non-renin-producing hypertension that was controlled medically, one case of nephroblastomatosis found in the removed dysplastic kidney, and one case of pyelonephritis in the contralateral kidney. When the diagnosis of classic MCDK is made with imaging modalities, the lesion may not have to be removed unless there is growth of the mass during the 1st year of life. Nine percent of these lesions will disappear within the first 3 years of follow-up, and the authors recommend an even longer period of follow-up.     

Renal allograft rejection: evaluation by Doppler US and MR imaging

A prospective study compared the efficacy of Doppler ultrasonography (US) and magnetic resonance (MR) imaging in evaluating 38 renal allografts, with specific attention to transplant rejection. Forty-three Doppler US and 42 MR examinations were performed and interpreted. Histologic correlation was obtained from 22 biopsy or nephrectomy specimens. Clinical correlation or a response to instituted therapy was used as confirmation in the remaining allografts. Accuracy in identifying cyclosporine toxicity or acute tubular necrosis could not be evaluated because there were few such cases, with concomitant rejection in most. The ability to predict and identify presence or absence of rejection was not affected by different serum creatinine values. Doppler US was significantly superior to MR imaging in identifying allograft rejection, demonstrating a higher sensitivity (95% vs. 70%), specificity (95% vs. 73%), and accuracy (95% vs. 71%). Because of its low cost and accessibility, Doppler US should become the primary modality for renal transplant screening.