Intracellular signaling pathways that regulate dendritic spine morphogenesis

Rac is a member of the Rho family of small GTPases and acts as a molecular switch. When GTP-bound, Rac binds specific effectors to induce downstream signaling events, including actin cytoskeletal rearrangements (Hall, Science 1998;279:509-514). Herein we review the recent evidence suggesting that Rac is involved in the morphogenesis of dendritic spines (Luo et al., Nature 1996;379:837-840; Nakayama et al., J Neurosci 2000; 20:5329-5338). In addition, we discuss how Rac activity is regulated by guanine nucleotide exchange factors, which may be further regulated by extracellular factors. Thus, the Rac signal transduction pathway may provide links between extracellular ligands or synaptic activity and the regulation of the actin cytoskeleton in spine morphogenesis.     

Pelvic insufficiency fractures in postmenopausal woman with advanced cervical cancer treated by radiotherapy.

PURPOSE: To assess the predisposing factors and clinical characteristics of pelvic insufficiency fractures (PIF) in postmenopausal women with pelvic irradiation. MATERIAL AND METHODS: A total 335 postmenopausal patients with cervical cancer of the intact uterus treated with radiation therapy between 1983 and 1998 were reviewed. Total external dose was delivered between 45 and 50.4 Gy with parallel opposed anteroposterior portals. Total brachytherapy dose at point A was delivered between 10 and 36 Gy. PIF were diagnosed by bone scintigraphy and confirmed by computed tomography. The cumulative incidence of symptomatic PIF was estimated by actuarial methods. Potential risk factors (age, weight, type II diabetes, delivery, menopause, total external dose, total brachytherapy dose) were assessed. RESULTS: Fifty-seven (17.0%) of 335 patients were diagnosed as having PIF. Forty-seven patients were symptomatic and ten were asymptomatic. Parameters carrying a significant association with PIF were body weight 49 kg or below (P=0.044) in stepwise logistic regression analysis. The cumulative incidence of symptomatic PIF at 5 years was 17.9% calculated by the Kaplan-Meier method. A body weight of 49 kg or below and more than three deliveries were identified as having a significant effect on symptomatic PIF in univariate analysis (P=0.021, P=0.003, log-rank test) and Cox life table regression analysis (P=0.038, P=0.013). Five patients required narcotic agents and eight patients required hospital admission. CONCLUSIONS: We should consider reducing the dose contribution to the sacrum and sacroilac joints, without underdosing the tumor, especially in postmenopausal women with many deliveries or low body weight.     

DIAGNOSIS OF CONGENITAL CYTOMEGALOVIRUS INFECTION BY EXAMINATION OF PLACENTA: Application of Polymerase Chain Reaction and in Situ Hybridization

We examined the placentas of 12 patients in whom congenital cytomegalovirus CMV infection was suspected from serological and or pathological evaluation. Seven patients died including four intrauterine deaths and five survived. On histological examination, the characteristic inclusion bodies were detected in only three placentas, and villitis with plasma cell infiltration was seen in eight placentas. Immunohistochemistry using a specific antibody against CMV improved the sensitivity of CMV detection 10 cases were positive . With the polymerase chain reaction PCR following the extraction of DNA from formaldehyde-fixed placenta samples, CMV DNA was detected in seven cases. All 12 subjects were diagnosed with CMV infection by additional Southern blot analysis after the PCR. CMV DNA was also detected by an in situ hybridization method in all cases. With current molecular biological techniques the placenta can be reliably used for the diagnosis of congenital CMV infection.     

A lethal osteochondrodysplasia with mesomelic brachymelia, round pelvis, and congenital hepatic fibrosis: two siblings born to consanguineous parents

We report a hitherto unknown, lethal osteochondrodysplasia in two Japanese siblings born to consanguineous parents. The skeletal abnormalities are characterised by mesomelic brachymelia with bowed forearms, a round pelvis with shortened greater sciatic notches, an ossification defect of the pubic bones, and absence of ossification centers in the cervical vertebral bodies. The associated visceral anomalies comprised periportal fibrosis and cystic dysplasia of the intrahepatic bile ducts, pancreatic ductal ectasia, a simple renal cyst, microcephaly with multifocal laminar necrosis and ectopic gray matter, dysplastic tracheobronchial cartilage, abnormal lobulation of the lung, diaphragmatic hernia, and stenotic pulmonary valve. Thrombocytopenia was present but megakaryocytes were slightly increased in the bone marrow. The patients showed various dysmorphic features including aniridia, a long palpebral fissure, prominent nasal bridge, beaked nose, flat philtrum, low-set fleshy ears, micrognathia with submucosal cleft palate, and multiple joint contractures. Received: 23 May 1997 Accepted: 27 June 1997     

Mutation Analysis of the WT1 Gene in Myelodysplastic Syndromes

The WT1 tumor suppressor gene was examined for mutations in a panel of 44 patients with myelo-dysplastic syndromes (MDS) including acute myelogenous leukemias (AML) secondary to MDS, using polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) analysis and sequencing analysis. A WT1 mutation was detected in one out of 17 cases of AML secondary to MDS. This mutation exists upstream of the zinc finger region and is predicted to produce a truncated WT1 protein lacking the zinc finger region. No mutations were detected in 27 MDS patients who had not progressed to AML. This is the first report of analysis for WT1 mutations in a large number of MDS patients, suggesting that WT1 mutations are uncommon in MDS. Abnormalities in this gene may, however, contribute to a small proportion of cases showing progression from MDS into AML.     

Diagnosis of chest wall invasion by lung cancer: useful criteria for exclusion of the possibility of chest wall invasion with MR imaging

PURPOSE: To compare the accuracy of thin-section CT, conventional static MR imaging (conventional MRI), and breathing dynamic echo planar magnetic resonance imaging (BDEPI) in evaluating lung cancer invasion to the chest wall. MATERIALS AND METHODS: Thin-section CT, conventional MRI, and BDEPI were performed preoperatively in 20 patients suspected of having primary lung cancers adjacent to the chest wall on conventional CT. The results of imaging findings were compared with those of surgical and histopathological findings. RESULTS: All patients were confirmed to have no chest wall invasion after surgery. By thin-section CT, 10 of 20 patients were correctly diagnosed as having no chest wall invasion (50% specificity). Two of the 20 patients were incorrectly diagnosed as having chest wall invasion by conventional MRI and BDEPI (90% specificity). CONCLUSION: When chest wall invasion is suspected on CT scans, static and breathing dynamic MRI are recommended to avoid false positive interpretations.     

Pharmacological characterization of a novel AVP(4-9) binding site in rat hippocampus

pGlu-Asn-Cys (Cys)-Pro-Arg-Gly-NH(2) (AVP(4-9)), a major metabolite C-terminal fragment of Arginine(8)-vasopressin (AVP), improves the disruption of the learning and memory, and is a far more potent in the mnemonic function than AVP. In this study, we pharmacologically characterized its putative binding site and mechanism of intracellular signaling. Radioligand binding assay showed that [35S]AVP(4-9) could detect specific binding sites in the rat hippocampus membrane preparations, and the binding site was specifically displaced by AVP(4-9) but not by either V(1) or V(2) antagonists. Furthermore, [35S]AVP(4-9) could not detect the cloned rat V(1a), V(1b) and V(2) vasopressin receptors. Even at a low doses (10-100 pM), AVP(4-9) caused an increase in both inositol(1,4, 5)-trisphosphate (Ins(1,4,5)P(3)) and intracellular calcium concentrations ([Ca(2+)](i)) in rat hippocampal cells. The AVP(4-9)-induced [Ca(2+)](i) increase was partially inhibited by the absence of Ca(2+) or by Ca(2+)-channel blocker, suggesting that AVP(4-9) caused the [Ca(2+)](i) increase via release from intracellular calcium store as well as influx from extracellular calcium. For the first time, this study provides evidence to show that AVP(4-9) activates Ins(1,4,5)P(3)/[Ca(2+)](i) pathway through a novel type of receptor in rat hippocampus, which might be potentially important in improving the mnemonic function.     

Thoracoscopic lobectomy (non rib-spreading method): versus a video assisted lobectomy and a conventional thoracotomy

We analyzed 33 thoracoscopic lobectomy (non rib-spreading method: NR) cases and 33 video assisted lobectomy (VA) cases and 49 posterolateral thoracotomy (PL) cases, regarding post-operative changes in the serum enzyme levels, operative bleeding, required analgesic treatments, changes in the respiratory function and other factors. Regarding the post/pre-operative ratio of creatinin phosphokinase, bleeding and analgesic treatment NR was showed significantly lower levels than the other two methods. Regarding the post/pre-operative ratio of vital capacity of the lung NR was significantly less than PL for every six months after the operation. With NR the mean number of dissected mediastinal nodes was 14.2 +/- 7.4 which was not significantly different from VA and PL. We thus concluded that NR caused less thoracotomic damage and especially far less restrictive damage to the respiratory function than both PL and VA. NR may also result in a better quality of life than VA and PL. The node dissection required for NR is also not considered to be inferior to that for PL because the number of dissected nodes for NR was not significantly different from that for PL. Therefore, in cases presenting with clinical stage I primary lung cancer NR is thus considered to be indicated in order to obtain an improved post-operative quality of life.