Genetic risk of neuropsychological impairment in schizophrenia: a study of monozygotic twins discordant and concordant for the disorder

We investigated the effect of the adenosine receptor agonist 5'-(N-ethylcarboxamido)adenosine (NECA) in catecholamine secretion from adrenal chromaffin cells that exhibit only the A2b subtype adenosine receptor. NECA reduced catecholamine release evoked by the nicotinic agonist 1,1-dimethyl-4-phenylpiperazinium (DMPP) in a time-dependent manner. Inhibition reached 25% after 30-40-min exposure to NECA. This effect on DMPP-evoked catecholamine secretion was mirrored by a similar (27.7 +/- 3.3%), slowly developing inhibition of [Ca2+]i transients induced by DMPP that peaked at 30-min preincubation with NECA. The capacity of the chromaffin cells to buffer Ca2+ load was not affected by the treatment with NECA. Short-term treatment with NECA failed both to modify [Ca2+]i levels and to increase endogenous diacylglycerol production, showing that NECA does not activate the intracellular Ca2+/protein kinase C signaling pathway. The inhibitory effects of NECA were accompanied by a 30% increase of protein phosphatase activity in chromaffin cell cytosol. We suggest that dephosphorylation of a protein involved in DMPP-evoked Ca2+ influx pathway (e.g., L-type Ca2+ channels) could be the mechanism of the inhibitory action of adenosine receptor stimulation on catecholamine secretion from adrenal chromaffin cells.     

Single-cell measurements of human neutrophil activation using electrorotation

We have used the technique of cell electrorotation within a microfabricated planar gold electrode array as a means of detecting changes in the physical properties of a single human neutrophil, when activated by the chemotactic factor, phorbol myristate acetate (PMA). The results, which have been analyzed using a double-shell model to represent the cell and its nucleus, provide an indication of the changes in biophysical parameters that occur during cell activation. The methods used in this study have potential applications in the development of single-cell assays for pharmaceutical screening, as a means of determining rapidly the action of drugs.     

Monocyte tissue factor-like activity in post myocardial infarction patients

It is widely recognized that thrombosis is the major event in the evolution of stable vascular disease to unstable ischaemic syndromes including myocardial infarction and stroke. The purpose of this case-control study was to establish clinical and laboratory data on the possible relationship between specific components of the haemostatic system and coronary heart disease. The procoagulant activity (PCA) of peripheral monocytes and polymorphonuclear neutrophils was assessed in 21 males who had suffered a myocardial infarction (MI) and in age-matched controls. In addition, total factor VII activity, fibrinogen, tissue factor pathway inhibitor (TFPI). D-dimers, tissue plasminogen activator (t-PA), plasminogen activator inhibitor (PAI-1), tumour necrosis factor-alpha (TNF-alpha) and full blood counts were measured. Post MI patients had significantly higher monocyte PCA, higher plasma concentrations of TFPI, fibrinogen, t-PA, T/P100 and also higher total white blood cell and neutrophil counts compared to age-matched controls. This elevated procoagulant state in post MI patients could further exacerbate the disease process and increase the risk of subsequent acute ischaemic events.     

Uretero-iliac fistula

OBJECTIVE: To describe a case of uretero-iliac fistula, an extremely rare condition that is not easily diagnosed. METHODS/RESULTS: Herein we describe a 76-year-old female who had undergone repeated pelvic surgery for adenocarcinoma of the sigmoid. She had a right ureteral fistula that had been managed conservatively by insertion of a ureteral catheter. Diagnosis was made by selective arteriography of the iliac arteries. The patient was submitted to surgery; primary closure of the arterial fistula and nephroureterectomy were performed. CONCLUSIONS: Uretero-iliac fistula should be suspected in patients with a history of repeated pelvic surgery and ureteral catheter placement that present with massive hematuria.     

Effects of general receptor for phosphoinositides 1 on insulin and insulin-like growth factor I-induced cytoskeletal rearrangement, glucose transporter-4 translocation, and deoxyribonucleic acid synthesis

We investigated the effects of general receptor for phosphoinositides-1 (GRP1), a recently cloned protein that binds 3,4,5-phosphatidylinositol [PtdIns(3,4,5)P3] with high affinity, but not PtdIns(3,4)P2 nor PtdIns(3)P, on insulin and insulin-like growth factor I (IGF-I)-induced cytoskeletal rearrangement, glucose transporter-4 (GLUT4) translocation, and DNA synthesis. GRP1 consists of an NH2-terminally located coiled coil domain followed by a Sec7 domain and a COOH-terminal pleckstrin homology (PH) domain that is required for PtdIns binding. We used microinjection of glutathione-S-transferase fusion proteins containing residues 239-399 (PH domain), residues 52-260 (Sec7 domain), residues 5-71 (N-terminal domain), full-length GRP1, and an antibody (AB) raised against full-length GRP1 coupled with immunofluorescent detection of actin filament rearrangement, GLUT4 translocation, and 3'-bromo-5'-deoxyuridine incorporation. Microinjection of these constructs and the AB had no effect on insulin-induced GLUT4 translocation or DNA synthesis. However, microinjection of the GRP1-PH and the GRP1-Sec7 domain as well as the alpha-GRP1-AB significantly inhibited insulin- and IGF-I-stimulated actin rearrangement in an insulin receptor-overexpressing cell line (HIRcB) compared with that in control experiments. Coinjection of GRP1-Sec7 along with constitutively active Rac (Q67L) did not inhibit Rac-induced actin rearrangement. Furthermore, GRP1 is not able to bind and act as a nucleotide exchange factor for the small GTP-binding proteins of the Rho family. As GRP1 acts as a guanine nucleotide exchange factor for ARF6 proteins, we propose a signaling pathway distinct from the small GTP-binding protein Rac, connecting PtdIns(3,4,5)P3 via GRP1 to ARF6, leading to insulin- and IGF-I-induced actin rearrangement.     

G alphas-induced neurodegeneration in Caenorhabditis elegans

We describe a genetic model for neurodegeneration in the nematode Caenorhabditis elegans. Constitutive activation of the GTP-binding protein Galphas induces neurodegeneration. Neuron loss occurs in two phases whereby affected cells undergo a swelling response in young larvae and subsequently die sometime during larval development. Different neural cell types vary greatly in their susceptibility to Galphas-induced cytotoxicity, ranging from 0 to 88% of cells affected. Mutations that prevent programmed cell death do not prevent Galphas-induced killing, suggesting that these deaths do not occur by apoptosis. Mutations in three genes protect against Galphas-induced cell deaths. The acy-1 gene is absolutely required for neurodegeneration, and the predicted ACY-1 protein is highly similar (40% identical) to mammalian adenylyl cyclases. Thus, Gs-induced neurodegeneration is mediated by the second messenger cAMP. Mutations in the unc-36 and eat-4 genes are partially neuroprotective, which indicates that endogenous signaling modulates the severity of the neurotoxic effects of Galphas. These experiments define an intracellular signaling cascade that triggers a necrotic form of neurodegeneration.     

Estimates of the virological benefit of antiretroviral therapy are both assay- and analysis-dependent

OBJECTIVE: To assess the potential discrepancies in reported changes in plasma viral load (PVL) depending on how values below the detection limit of the assay are handled in the data analysis phase of a randomized controlled clinical trial. DESIGN: Data from a recently completed clinical trial comparing combinations of zidovudine, didanosine and nevirapine were analysed. In this trial, PVL was measured using an assay with a lower quantification limit of 400 HIV-1 RNA copies/ml initially. All PVL values less than 500 copies/ml were retested with a more sensitive assay with a lower quantification limit of 20 copies/ml. METHODS: Several summary measures for assessing change in PVL were calculated using three different methods to adjust for PVL values less than the quantification limit of the assay. The differences between these measures were evaluated. RESULTS: We found that the magnitude of the discrepancy between summary measures used to report changes in PVL depended on the proportion of subjects with PVL less than the quantification limit of the assay, how those observations were handled in the data analysis, and the relative difference between the quantification limits of the conventional and more sensitive assay. CONCLUSION: The lack of consensus in reporting of PVL data in the literature makes the interpretation of published trial results difficult. In the absence of agreement on the most appropriate summary measure of PVL data, we recommend that all summaries include information on the quantification limit of the assay used, the proportion of observations at or below the quantification limit and how these observations were handled in the data analysis.     

Influence of non-inherited maternal HLA-DR antigens on susceptibility to rheumatoid arthritis

OBJECTIVE: It has recently been observed that non-inherited maternal DR4 antigens (NIMAs) of DR4 negative rheumatoid arthritis (RA) patients were increased compared with non-inherited paternal DR4 antigens (NIPAs). The aim of this study was to determine the prevalence of non-inherited DR4 antigens and DRB1 alleles in parents of RA patients. METHODS: HLA-DR serology and DRB1 typing was performed in 97 RA patients and their parents. NIMA and NIPA frequencies were compared, stratified according to the presence of DR4 and/or the shared epitope (SE). RESULTS: In DR4 negative patients, NIMA DR4 was increased compared with NIPA DR4 (OR 3.10, 95% CI 0.76, 12.70). When combined with results from a previous study this increase was significant (OR 3.65, 95% CI 1.29, 10.31). The NIMA effect of SE positive DR4 subtypes in this study (OR 4.73, 95% CI 0.94, 23.8) was stronger than the NIMA effect of combined SE positive DRB1 alleles (OR 2.19 95% CI 0.36, 13.22). CONCLUSIONS: The association between non-inherited maternal HLA-DR4 alleles and the susceptibility to RA was observed in two independent populations.     

Sequence alterations of insulin-like growth factor binding protein 3 in neoplastic and normal gastrointestinal tissues

Insulin-like growth factor binding protein 3 (IGFBP-3) is an important regulator of normal and malignant cell growth. It modulates the mitogenic effects of insulin-like growth factors (IGFs) by inhibiting growth through mechanisms both dependent on and independent of IGF binding. IGF-I and IGF-II levels are regulated by binding to the IGF-II receptor, which is inactivated by mutation in human gastrointestinal (GI) tumors. We have previously demonstrated elevated IGF-II ligand expression in IGF-II receptor-mutant GI tumors, implicating the IGF signaling system in GI tumorigenesis. Therefore, to investigate the potential involvement of IGFBP-3 in human GI carcinogenesis, direct DNA sequencing of exons 1-4 and intron-exon boundaries of the IGFBP-3 gene was performed in 10 colorectal cancers, 10 gastric cancers, and 10 esophageal cancers. Four distinct sequence alterations were identified: (a) in one gastric and one esophageal tumor, an A to C transversion occurred at nucleotide 5795 (CAC-->CCC), leading to a His-->Pro substitution at codon 179; (b) a second esophageal tumor had a C to T transition at nucleotide 8291 (ACC-->ATC), leading to a Thr-->Ile substitution at codon 277 of IGFBP-3; (c) one alteration comprised a G to C transversion in exon 1 at nucleotide 2132 (GGG-->GCG), leading to a Gly-->Ala substitution at codon 32 in two gastric cancers, seven esophageal cancers, and nine colon cancers; and (d) a C to G transversion located 17 nucleotides from the 3' splice site in intron 1 was observed in three colon cancers and four esophageal cancers. All of these DNA sequence alterations were present in matched normal DNA from the same subjects, which suggests that some or all of them may represent polymorphisms. However, we cannot exclude the possibility that the germ-line nonconservative amino acid substitutions predicted to occur as a result of these alterations result in subtle changes to IGFBP-3 protein function and a predisposition to developing GI malignancy.