Biochemical analysis of ++Prospero protein during asymmetric cell division: cortical Prospero is highly phosphorylated relative to nuclear Prospero

Hippocampal synapses express two distinct forms of the long-term potentiation (LTP), i.e. NMDA receptor-dependent and -independent LTPs. To understand its molecular-anatomical basis, we produced affinity-purified antibodies against the GluRepsilon1 (NR2A), GluRepsilon2 (NR2B), and GluRzeta1 (NR1) subunits of the N-methyl-D-aspartate (NMDA) receptor channel, and determined their distributions in the mouse hippocampus. Using NMDA receptor subunit-deficient mice as the specificity controls, section pretreatment with proteases (pepsin and proteinase K) was found to be very effective to detect authentic NMDA receptor subunits. As the result of modified immunohistochemistry, all three subunits were detected at the highest level in the strata oriens and radiatum of the CA1 subfield, and high levels were also seen in most other neuropil layers of the CA1 and CA3 subfields and of the dentate gyrus. However, the stratum lucidum, a mossy fibre-recipient layer of the CA3 subfield, contained low levels of the GluRepsilon1 and GluRzeta1 subunits and almost excluded the GluRepsilon2 subunit. Double immunofluorescence with the AMPA receptor GluRalpha1 (GluR1 or GluR-A) subunit further demonstrated that the GluRepsilon1 subunit was colocalized in a subset, not all, of GluRalpha1-immunopositive structures in the stratum lucidum. Therefore, the selective scarcity of these NMDA receptor subunits in the stratum lucidum suggests that a different synaptic targeting mechanism exerts within a single CA3 pyramidal neurone in vivo, which would explain contrasting significance of the NMDA receptor channel in LTP induction mechanisms between the mossy fibre-CA3 synapse and other hippocampal synapses.     

A study of the mechanism of inhibition of fibrinolysis by activated thrombin-activable fibrinolysis inhibitor

TAFI (thrombin-activable fibrinolysis inhibitor) is a recently described plasma zymogen that, when exposed to the thrombin-thrombomodulin complex, is converted by proteolysis at Arg92 to a basic carboxypeptidase that inhibits fibrinolysis (TAFIa). The studies described here were undertaken to elucidate the molecular basis for the inhibition of fibrinolysis. When TAFIa is included in a clot undergoing fibrinolysis induced by tissue plasminogen activator and plasminogen, the time to achieve lysis is prolonged, and free arginine and lysine are released over time. In addition, TAFIa prevents a 2.5-fold increase in the rate constant for plasminogen activation which occurs when fibrin is modified by plasmin in the early course of fibrin degradation. The effect is specific for the Glu- form of plasminogen. TAFIa prevents or at least attenuates positive feedback expressed through Lys-plasminogen formation during the process of fibrinolysis initiated by tissue plasminogen activator and plasminogen. TAFIa also inhibits plasmin activity in a clot and prolongs fibrinolysis initiated with plasmin. We conclude that TAFIa suppresses fibrinolysis by removing COOH-terminal lysine and arginine residues from fibrin, thereby reducing its cofactor functions in both plasminogen activation and the positive feedback conversion of Glu-plasminogen to Lys-plasminogen. At relatively elevated concentrations, it also directly inhibits plasmin.     

Statistical issues in biological radiation dosimetry for risk assessment using stable chromosome aberrations

Biological dosimeters are useful for epidemiologic risk assessment in populations exposed to catastrophic nuclear events and as a means of validating physical dosimetry in radiation workers. Application requires knowledge of the magnitude of uncertainty in the biological dose estimates and an understanding of potential statistical pitfalls arising from their use. This paper describes the statistical aspects of biological dosimetry in general and presents a detailed analysis in the specific case of dosimetry for risk assessment using stable chromosome aberration frequency. Biological dose estimates may be obtained from a dose-response curve, but negative estimates can result and adjustment must be made for regression bias due to imprecise estimation when the estimates are used in regression analyses. Posterior-mean estimates, derived as the mean of the distribution of true doses compatible with a given value of the biological endpoint, have several desirable properties: they are nonnegative, less sensitive to extreme skewness in the true dose distribution, and implicitly adjusted to avoid regression bias. The methods necessitate approximating the true-dose distribution in the population in which biological dosimetry is being applied, which calls for careful consideration of this distribution through other information. An important question addressed here is to what extent the methods are robust to misspecification of this distribution, because in many applications of biological dosimetry it cannot be characterized well. The findings suggest that dosimetry based solely on stable chromosome aberration frequency may be useful for population-based risk assessment.     

Pretreatment evaluation of chronic hepatitis C: risks, benefits, and costs

CONTEXT: Chronic hepatitis C (CHC) infection affects nearly 4 million people in the United States. Treatment with interferon alfa-2b has been limited by its cost and low likelihood of long-term response. OBJECTIVE: To examine the cost-effectiveness of alternative pretreatment management strategies for patients with CHC. DESIGN: Decision and cost-effectiveness analysis using a Markov model to examine prevalence of genotypes, viral load, and histological characteristics in relation to the sustained response rate with treatment. Data were based on a previously published decision model and a MEDLINE literature search for hepatitis C, biopsy, and liver from 1966 to 1996. PATIENTS: A hypothetical population of patients with CHC infection and elevated serum alanine aminotransferase level. INTERVENTIONS: Combinations of liver biopsy, genotyping, and quantitative viral load determination prior to a single 6-month course of interferon alfa-2b; empirical interferon treatment; and conservative management. MAIN OUTCOME MEASURES: Proportion of sustained responders, lifetime costs, life expectancy, and quality-adjusted life expectancy. RESULTS: Strategies involving hepatitis C virus (HCV) RNA testing had marginal cost-effectiveness ratios up to $4400 per discounted quality-adjusted life-year gained but would miss up to 36% of sustained responders. Empirical interferon treatment had a marginal cost-effectiveness ratio of $12400 per discounted quality-adjusted life-year gained and reached all potential sustained responders. Strategies involving liver biopsy were more expensive and would miss 6% of sustained responders and yield slightly lower life expectancies. CONCLUSIONS: Routine liver biopsy before treatment with interferon increases the cost of managing patients with CHC without improving health outcomes. Using quantitative HCV RNA testing to guide therapy misses some potential sustained responders. Empirical interferon treatment has a marginal cost-effectiveness ratio within the bounds of other commonly accepted therapies and misses none of the sustained responders.     

Comparison of ketoconazole and fluconazole as cytochrome P450 inhibitors. Use of steady-state infusion approach to achieve plasma concentration-response relationships

OBJECTIVE: To define factors causing prolonged labor in nulliparous women undergoing active management of labor. METHODS: We included all nulliparas delivered during 1990-1994 with spontaneous onset of labor lasting more than 12 hours, singleton gestation, cephalic presentation, and labor at greater than 37 weeks. Each patient was matched with the next nulliparous woman who delivered with a labor lasting less than 12 hours and who fulfilled the same inclusion criteria. Subjects were managed according to the previously described active management of labor protocol from The National Maternity Hospital, Dublin. RESULTS: In the 5-year period, 9018 nulliparas met inclusion criteria, with 147 (1.6%) having prolonged labor. Prolonged labor was due to inefficient uterine action in 65%, persistent occipitoposterior position in 24%, and cephalopelvic disproportion in 11% of cases. Univariate analysis showed statistically significant (P < .05) differences in maternal body mass index, cervical dilation on admission, oxytocin use, epidural use, placement of epidural at less than 2 cm of dilation, and birth weight between these study groups. On multivariate conditional logistic regression analysis, the following were significant independent predictors for having a prolonged labor (odds ratios with 95% confidence intervals presented): 3.1 (1.3-7.3) for cervical dilation less than 2 cm on admission, 42.7 (7.5-242.0) for early epidural placement, 5.1 (1.9-13.7) for epidural placement at greater than or equal to 2 cm, and 10.2 (3.6-29.4) for birth weight greater than 4000 g. CONCLUSION: Less-advanced cervical dilation on admission and epidural use, especially when placed early, are strongly associated with prolonged labor.     

Localization and regulation of renal Na+/myo-inositol cotransporter in diabetic rats

We have examined the effect of diabetes on sodium/myo-inositol cotransporter (SMIT) mRNA levels and myo-inositol content in the kidney to test the hypothesis that diabetes-induced changes in renal myo-inositol levels are due to the regulation of SMIT mRNA levels. In streptozotocin-induced diabetic rats, after 3, 7 and 28 days of diabetes, SMIT mRNA levels in the whole kidney were increased three to fivefold, and remained increased by about twofold after six months of diabetes. Insulin treatment of diabetic rats normalized blood glucose levels and prevented the increase in SMIT mRNA levels. Treating diabetic rats with sorbinil, an aldose reductase inhibitor, corrected the abnormal accumulation of sorbitol but had no effect on the diabetes-induced increase in renal SMIT mRNA levels. The regional distribution of SMIT mRNA from normal rats showed a relative abundance in cortex, outer medulla, and inner medulla of 1.0:3.4:7.0. After seven days of diabetes, the levels of SMIT mRNA and myo-inositol content were significantly increased only in the outer medulla. In situ hybridization studies revealed that SMIT mRNA in the outer medulla was predominately localized to the medullary thick ascending limbs of Henle's loop and was not localized to any specific cell in the inner medulla. This distribution pattern was unchanged in diabetic rats. These studies show that diabetes causes an increase in renal SMIT mRNA, which is primarily localized to the outer medulla. Accumulation of myo-inositol by the thick ascending limb of Henle's loop may account for most of the increase caused by diabetes.     

Solitary rectal ulcer syndrome

BACKGROUND: Solitary rectal ulcer syndrome is a rare disorder characterized by erythema or ulceration of the rectal wall, associated with typical histological features, and disturbed defaecatory behaviour with the passage of blood and mucus. METHODS: This is a review based on a literature search using a computer database (Medline) and manual cross-referencing. RESULTS: The pathogenesis is likely to vary in different patients; it includes trauma from straining, direct digital trauma and possibly primary neuromuscular pathology. The histological findings of extension of the muscularis mucosa between crypts and muscularis propria disorganization on full-thickness specimens are characteristic. Biofeedback defaecation retraining, including habit training, can lead to symptom improvement and return to work in a majority of patients. Abdominal rectopexy offers long-term symptom improvement in approximately 50 per cent of patients. Rectal ulceration may persist after any treatment, even if symptoms improve. CONCLUSION: Behavioural therapy and carefully considered operations offer the best treatment results. Further work on psychological factors and neuromuscular and vascular pathology is required.     

Gastrointestinal manifestations of vascular anomalies in childhood: varied etiologies require multiple therapeutic modalities

BACKGROUND/PURPOSE: Vascular anomalies, including hemangiomas and vascular malformations afford complex diagnostic and therapeutic challenges when gastrointestinal (GI) manifestations are present. METHODS: Twenty-one patients evaluated or treated in our Vascular Anomalies Program from 1993 through 1997 were reviewed retrospectively with regard to presentation, treatment modalities, and outcome. RESULTS: Four patients had hemangiomas, and 17 had various vascular malformations. GI symptoms began in infancy or early childhood in all patients. Manifestations included GI bleeding (n = 15), obstruction (n = 2), diarrhea (n = 2), ascites (n = 2), pain (n = 1), emesis (n = 1), ileo-ileal intussusception (n = 1), protein-losing enteropathy (n = 1), and hypersplenism (n = 1). Four patients had proven portal hypertension. Fourteen had associated musculoskeletal or cutaneous lesions. Congestive heart failure, partial anomalous pulmonary venous return, pulmonary edema, and pleural or pericardial effusion occurred in one patient each. Bleeding was the most common symptom of both hemangiomas and malformations. Of four patients with hemangiomas, three were treated with corticosteroids or interferon. Endoscopic banding and embolization of an associated arterioportal hepatic shunt were each used in one patient. One patient died. The malformations were treated with resection (n = 8), endoscopic banding or sclerosis (n = 7), percutaneous or intraoperative sclerosis (n = 5), embolization or device interruption (n = 3), and portosystemic shunt (n = 2). GI symptoms were ameliorated in 12 patients with malformation, improved in two, unchanged in two, and one died after prolonged palliation. CONCLUSIONS: Vascular anomalies with gastrointestinal manifestations are heterogeneous in their presentation and type. Although bleeding is the most common symptom of both hemangiomas and vascular malformations, treatment differs. Pharmacological angiogenesis inhibition is the mainstay of hemangioma therapy. Resection, endoscopic or radiologic vascular obliteration, and portal decompression are important in treating vascular malformations. An individualized and interdisciplinary approach is often required to successfully diagnose and treat these complex lesions.     

Randomized controlled trial of omeprazole or endoscopy in patients with persistent dyspepsia: a cost-effectiveness analysis

BACKGROUND: Cost-effectiveness analysis, Helicobacter pylori research and the development of proton pump inhibitors are having an increasing impact on the management of dyspepsia. However, clinical trials have not always included both H. pylori diagnosis and proton pump inhibitors in their protocols. METHODS: Patients who were referred for upper gastrointestinal endoscopy by their general practitioner were randomized to either prompt endoscopy followed by directed medical treatment (conventional group, n=38), or to empirical treatment with omeprazole and, in the case of symptom relapse, serological screening for H. pylori infection followed by eradication therapy in seropositive patients (empirical group, n=42). The study lasted for up to 1 year. RESULTS: In the empirical group, only 13 patients (31%) underwent endoscopy. The average number of days for which the patients kept records of their dyspeptic symptoms was 266 (95% CI: 226-307) in the empirical group, of which 166 (95% CI: 128-204) were symptom-free. In the conventional group, 159 (95% CI: 119-198) out of 255 days (95% CI: 209-302) were recorded as symptom-free. The average medical cost in the empirical group was $284 (95% CI: 218-350) and in the conventional group $491 (95% CI: 383-600). In the empirical group, two malignancies were found, whereas in the conventional group one malignancy was found. CONCLUSIONS: The empirical drug treatment strategy in patients with persistent dyspeptic symptoms resulted in 69% fewer diagnostic endoscopies with lower medical costs and equal effectiveness in the first year, compared to prompt endoscopy followed by directed medical treatment.     

Clinical utility of autoantibodies in Guillain-Barre syndrome and its variants

In children and adolescents, primary neoplasms of the tracheobronchial tree and lungs are rare, with most tumors involving the respiratory system being metastatic, small, blue cell tumors of childhood. Of the primary pulmonary neoplasms, most are malignant with mucoepidermoid carcinoma representing about 10% of these malignant tumors. We present an 8-year-old Hispanic male with hemoptysis and several episodes of pneumonia which initially was thought to be infectious upon biopsy during bronchoscopy, but proved to be mucoepidermoid carcinoma of the tracheobronchial tree by microscopic examination during an open lung biopsy. This rare tumor is more common in adults than in children, and infrequently presents with hemoptysis. Mucoepidermoid tumors of the tracheobronchial tree carry a more favorable prognosis in children than adults. In the adult population, the overall mortality is slightly less than 30%. In contrast, of the 31 reported cases of tracheobronchial mucoepidermoid carcinoma in pediatrics, all children are free of tumor involvement with a mean follow-up period of 5.8 years (range, 0.7-21 years). Based upon the available clinical outcome and survival data, it would appear that tracheobronchial mucoepidermoid carcinoma may be successfully managed by surgical intervention alone in children and adolescents.