A neosynthesis of sodium channels is involved in the evolution of the sodium current in isolated adult DUM neurons

Short-term culture of isolated adult dorsal unpaired median (DUM) neurons of the cockroach Periplaneta americana has been used to study the evolution of the sodium current during the time in culture after axotomy and deafferentation treatment. An increase in the maximum peak amplitude of the sodium current recorded under voltage-clamp conditions with the patch-clamp technique in the whole-cell recording configuration, was only observed between 24h and 72h (75%) without any modification of the kinetics and the voltage-dependence of the current. A decrease in the level of foetal calf serum in the culture medium reduces the amplitude of the sodium current on all days but does not affect its time-course of development which was on the contrary completely abolished by both protein synthesis inhibitors, actinomycin D and cycloheximide. The results obtained in these neurons strongly suggest that a neosynthesis of sodium channel proteins is involved in the evolution of the sodium current induced by axotomy and deafferentation.     

Expression of cytokeratins 7 and 20 in carcinomas of the extrahepatic biliary tract, pancreas, and gallbladder

BACKGROUND: Expression of cytokeratins 7 (CK7) and 20 (CK20) may help distinguish the site of origin for metastatic carcinomas. Little is known regarding their expression in biliary tract and pancreatic carcinomas. Our aim was to study the expression of CK7 and CK20 in these tumors. DESIGN: Fifty-three carcinomas of the extrahepatic bile ducts (n = 8), ampulla of Vater (n = 7), gallbladder (n = 11), and pancreas (n = 27), were retrieved from the surgical pathology files of the University of Massachusetts Medical Center. Formalin-fixed, paraffin-embedded sections were immunostained with mouse monoclonal antibodies to CK7 and CK20 using an avidin-biotin immunoperoxidase technique with microwave antigen retrieval. The percentage of cells positive for each antibody was assessed on a scale of 0 to 3 (0, <10%; 1+, 10% to 50%; 2+, 51% to 90%; 3+, >90%). RESULTS: The majority of carcinomas in all groups were positive for CK7 (CK7+) and negative for CK20 (CK20-). Of the CK7+ tumors, the majority of tumors in each group were 3+ positive. CONCLUSIONS: (1) Carcinomas of the extrahepatic biliary tract and pancreas are strongly positive for CK7 and negative for CK20 and can be included in the differential diagnosis of other carcinomas with this profile in metastatic sites. (2) The CK7/CK20 immunostaining profile will not identify the site of origin for tumors with extensive growth in the porta hepatis region.     

Occurrence of secretogranin II in the prolactin-immunoreactive neurons of the rat lateral hypothalamus: an in situ hybridization and immunocytochemical study

The occurrence of secretogranin II in a neuron population of the rat lateral hypothalamus specifically detected by an anti-serum to ovine prolactin was examined. As this population was previously reported to synthesize dynorphin, the distribution of neurons recognized by ovine prolactin-, dynorphin B- and secretogranin II anti-sera was investigated on adjacent sections of hypothalami. The prolactin immunoreactive neurons were the only cells in the lateral hypothalamus to be stained by secretogranin II anti-serum. Moreover, coupling immunocytochemical detection and in situ hybridization with an oligonucleotide probe complementary to secretogranin II mRNA showed that these neurons expressed the secretogranin II gene. These new findings should help to study the physiological role of the prolactin immunoreactive neurons of the lateral hypothalamus.     

Detection of extended broad-spectrum beta-lactamases inEnterobacteriaceae in four French hospitals

In 210 strains ofEnterobacteriaceae which were isolated in four hospitals and which showed reduced susceptibility to cefotaxime, high synergy was demonstrated between amoxicillin (20µg) + clavulanate (10µg) and cefotaxime (30µg) using a simple double-disk test. Isoelectric focusing on gel and specific iodometric detection using ceftriaxone identified four extended broad-spectrum-lactamases (isoelectric points 7.6, 6.3, 7.0 and 5.9) produced by the strains.     

Quantification of plasma and intracellular levels of the HIV protease inhibitor ritonavir by competitive ELISA

The HIV protease inhibitor ritonavir (Norvir; ABT-578), currently used in combination with nucleoside analogs and other protease inhibitors in anti-HIV therapy, has previously been quantified by an HPLC procedure. Here, we report the first convenient one-step competitive ELISA for measuring plasma and intracellular ritonavir in HIV patients. Anti-ritonavir antibody was raised in rabbits using ritonavir-KLH conjugate as immunogen, and the enzymatic tracer was prepared by coupling the drug to acetylcholine esterase. Samples for analysis were first extracted with methanol. Bound/free separation was achieved in a microtiter plate previously coated with anti rabbit IgG monoclonal antibody. Fifty percent inhibition was observed at 1 ng/ml ritonavir and the method accurately and specifically detected as little as 3-4 ng/ml of plasma ritonavir as well as intracellular drug in the peripheral blood mononuclear cells of patients undergoing ritonavir therapy. Within-run and day to day coefficients of variation were below 10% and the drugs currently used in HIV therapy did not interfere with the test. The ELISA was applied to the measurement of plasma ritonavir and to the determination of the extracellular/intracellular drug level ratios in HIV patients receiving long-term multidrug therapy.     

Screening of SLC26A4 (PDS) gene in Pendred's syndrome: a large spectrum of mutations in France and phenotypic heterogeneity

Sensorineural hearing defect and goiter are common features of Pendred's syndrome. The clinical diagnosis of Pendred's syndrome remains difficult because of the lack of sensitivity and specificity of the thyroid signs. The identification of PDS as the causative gene allowed molecular screening and enabled a re-evaluation of the syndrome to identify potential diagnostic characteristics. This report presents the clinical and genotypic findings of 30 French families, for whom a diagnosis of Pendred's syndrome had been made. Twenty-seven families had at least one mutated allele. Twenty-eight different mutations were identified, 11 of which had never been previously reported. The main clinical characteristics were: early hearing loss, fluctuation in terms of during deafness evolution, and the presence of an enlarged vestibular aqueduct.     

The mutational specificity of l-nitroso-6-nitropyrene in the lacI gene of Escherichia coli strains deficient in nucleotide excision repair

We have examined the mutational specificity of 1-nitroso-6-nitropyrene(1,6-NONP), an activated metabolite of the carcinogen 1,6-dinitropyrene,in the lacI gene of Escherichia coli strains which are deficientin nucleotide excision repair (strain NR6113,