The human glucagon receptor encoding gene: structure, cDNA sequence and chromosomal localization

Characterization of the human glucagon-receptor-encoding gene (GGR) should provide a greater understanding of blood glucose regulation and may reveal a genetic basis for the pathogenesis of diabetes. A cDNA encoding a complete functional human glucagon receptor (GGR) was isolated from a liver cDNA library by a combination of polymerase chain reaction and colony hybridization. The cDNA encodes a receptor protein with 80% identity to rat GGR that binds [¹²⁵I] glucagon and transduces a signal leading to increases in the concentration of intracellular cyclic adenosine 3′,5′-monophosphate. Southern blot analysis of human DNA reveals a hybridization pattern consistent with a single GGR locus. In situ hybridization to metaphase chromosome preparations maps the GGR locus to chromosome 17q25. Analysis of the genomic sequence shows that the coding region spans over 5.5 kb and is interrupted by 12 introns.     

Design and applications of a self-aligning liquid junction-electrospray interface for capillary electrophoresis-mass spectrometry

A simple self-aligning liquid junction-electrospray interface for coupling a capillary electrophoresis (CE) system to an atmospheric pressure ionization (API) mass spectrometer (CE-MS) was developed. In contrast to previous liquid junction interfaces, the self-aligning liquid junction interface simplifies the precise alignment of the CE capillary and the sprayer needle and uses a positive make-up flow. Several capillary CE-MS applications were run using both the self-aligning liquid junction interface and the widely used sheath flow interface for comparison purposes. The electrospray stability of the self-aligning liquid junction interface is consistently better even when non-volatile electrolyte solutions are used. At first, some band broadening was obtained with the self-aligning liquid junction interface. Experiments with different CE buffer systems suggested that this band broadening was caused by the materials used in constructing the interface. By using a more inert material for the sprayer needle, the self-aligning liquid junction exhibits excellent electrophoretic resolution, comparable sensitivity, and higher signal-to-noise ratios when run under the same conditions as the sheath flow interface.     

Treatment of menorrhagia during menstruation: randomised controlled trial of ethamsylate,mefenamic acid,and tranexamic acid.

OBJECTIVE: To compare the efficacy and acceptability of ethamsylate, mefenamic acid, and tranexamic acid for treating menorrhagia. DESIGN: Randomised controlled trial. SETTING: A university department of obstetrics and gynaecology. SUBJECTS: 76 women with dysfunctional uterine bleeding. INTERVENTIONS: Treatment for five days from day 1 of menses during three consecutive menstrual periods. 27 patients were randomised to take ethamsylate 500 mg six hourly, 23 patients to take mefenamic acid 500 mg eight hourly, and 26 patients to take tranexamic acid 1 g six hourly. MAIN OUTCOMES MEASURES: Menstrual loss measured by the alkaline haematin method in three control menstrual periods and three menstrual periods during treatment; duration of bleeding; patient''s estimation of blood loss; sanitary towel usage; the occurrence of dysmenorrhoea; and unwanted events. RESULTS: Ethamsylate did not reduce mean menstrual blood loss whereas mefenamic acid reduced blood loss by 20% (mean blood loss 186 ml before treatment, 148 ml during treatment) and tranexamic acid reduced blood loss by 54% (mean blood loss 164 ml before treatment, 75 ml during treatment). Sanitary towel usage was significantly reduced in patients treated with mefenamic acid and tranexamic acid. CONCLUSIONS: Tranexamic acid given during menstruation is a safe and highly effective treatment for excessive bleeding. Patients with dysfunctional uterine bleeding should be offered medical treatment with tranexamic acid before a decision is made about surgery.     

Identification of a locus involved in meningococcal lipopolysaccharide biosynthesis by deletion mutagenesis

A novel method for insertion/deletion mutagenesis in meningococci was devised. This consisted of ligating a digest of total chromosomal DNA to a 1.1 kb restriction fragment containing an erythromycin-resistance marker ( ermC ), and subsequent transformation of the ligation mixture into the homologous meningococcal strain H44/76. Southern blotting of a number of the resulting erythromycin-resistant transformants demonstrated that all carried the ermC gene inserted at different positions in the chromosome. Mutants with a specific phenotype were identified by screening with the anti-lipopolysaccharide (LPS) monoclonal antibody MN4A8B2, which is specific for immunotype L3. In this way, two independent L3-negative mutant strains were isolated. In transformation experiments with chromosomal DNA from these mutants, erythromycin-resistance and lack of MN4A8B2 reactivity were always linked, showing that the insertion/deletion was in a locus involved in LPS biosynthesis. On SDS–PAGE, the mutant LPS displayed an electrophoretic mobility intermediate between that produced by the previously isolated galE and rfaF mutant strains. Chemical analysis of the mutant LPS revealed that the structure was probably lipid A–(KDO)₂–(Hep)₂. Chromosomal DNA flanking the ermC insertion in these two mutant strains was cloned, and used as probe for the isolation of the corresponding region of the wild-type strain. From hybridization and polymerase chain reaction (PCR) analysis, it could be concluded that both mutations map to the same locus. The affected gene probably encodes the glycosyltransferase necessary for adding N -acetylglucosamine to heptose.     

Comparison of Type 2 Inositol 1,4,5-Trisphosphate Receptor Distribution and Subcellular Ca2+ Release Sites that Support Ca2+ Waves in Cultured Astrocytes

Abstract: We have examined the mechanisms that underlie Ca²⁺ wave propagation in cultured cortical astrocytes. Norepinephrine evoked Ca²⁺ waves in astrocytes that began at discrete initiation loci and propagated throughout the cell by regenerative amplification at a number of cellular sites, as shown by very high Ca²⁺ release rates at these regions. We have hypothesized previously that domains displaying elevated Ca²⁺ release kinetics in astrocytes may correspond to sites of high inositol 1,4,5-trisphosphate receptor (InsP₃R) density. To examine this possibility, we compared the distribution pattern of endoplasmic reticulum (ER) and InsP₃Rs with Ca²⁺ release kinetics in subcellular regions during propagation of norepinephrine-evoked waves. 3,3'-Dihexyloxacarbocyanine iodide staining revealed that the ER in astrocytes exists as a meshwork of membranes extending throughout the cells, including fine processes. A specific antibody directed against type 2 InsP₃Rs (InsP₃R2) detected a 260-kDa band in western blotting of astrocyte membranes. Immunocytochemistry using this antibody stained the entire ER system in a punctate, variegated manner. When Ca²⁺ responses and InsP₃R2 immunofluorescence were compared in the same cell, domains of elevated Ca²⁺ response kinetics (high amplitude and rapid rate of rise) showed significant positive correlation with high local intensity of InsP₃R2 staining. It appears, therefore, that specializations in the ER responsible for discrete local Ca²⁺ release sites that support regenerative wave propagation include increased levels of InsP₃R2 expression.     

几种红树植物幼苗中可溶性糖的含量

用Ｓｏｍｏｇｙｉ法测定了红海榄、木榄和秋茄３种红树植物幼苗的根、茎、叶和胚轴中可溶性糖的含量。同时．进行了加样回收率试验,回收率平均为１００．４８％,变异系数为２．１４％     

Biological maturation and β-adrenergic effectors: development of β-adrenergic receptors in rabbit heart

Summary The -adrenergic receptor, transduction processes and catalytic activity of the adenylate cyclase enzyme complex have been investigated in rabbit heart at different stages of biological maturation. The binding of [³H]-dihydroalprenolol to a washed membrane preparation isolated from rabbit ventricular muscle was used to characterize -adrenergic receptors. Significant age-related differences were noted in -receptor affinity (K_d) and density (RD) of neonatal and adult animals; the adult K_d was 3.7-fold greater and the RD 2-fold higher than the neonates. No significant differences in these parameters were detected among the 27-day old fetus and the 1- and 7-day old neonates. Age-dependent differences in agonist isoproterenol affinity for the receptor were not observed in contrast to the significant changes in antagonist (DHA) affinity.Age-related changes in receptor affinity were also quantitated by determining the inhibitory potency of alprenolol on isoproterenol stimulated adenylate cyclase enzyme activity. A decreased affinity of the -adrenergic receptor for alprenolol in the adult heart was indicated by a 3.7-fold greater K_i for the adult than the 1-day old neonate. Ontogenic variations in the coupling efficiency between the receptor and catalytic components of the adenylate cyclase complex were also evaluated. The K_d of the -adrenergic receptor for isoproterenol and the EC50 for adenylate cyclase stimulation were determined under similar conditions. The corresponding coupling index (K_d/EC50) was found to be 2.4-fold greater in the 1-day old neonate than adult, suggesting that for a given percentage increase in adenylate cyclase activity, a lower percentage of -adrenergic receptor sites need be occupied in the neonate. These data extend previous studies (29) and indicate all components of the rabbit heart adenylate cyclase enzyme complex (i.e., the -adrenergic receptor, the GTP-dependent transduction event, and the catalytic subunit) exhibit significant developmental changes.     

Dosage-mortality and time-mortality studies of a granulosis virus in a laboratory strain of the codling moth,Laspeyresia pomonella

Different doses of a granulosis virus were administered to first- and fifth-instar larvae of the codling moth Laspeyresia pomonella. Virus was very pathogenic for both larval instars. The LD₅₀ values for first- and fifth-instar larvae were 5 and 49 capsules/larva, respectively. However, fifth-instar larvae were much more variable in their response to virus than first-instar larvae. Using probit methods it was calculated that 1 capsule could cause death in about 25% of both larval instars but 1578 capsules were required to cause 70% mortality of fifth-instar larvae as compared to 12 capsules for first-instar larvae. This is the first report of a decided difference in variability of response to virus by two larval instars of the same species. A bimodal response by both larval instars was observed in time-mortality studies. Apparently, about 20% of the larvae were very resistant to virus infections.