Mechanism of Hyperinsulinism in Short-chain 3-Hydroxyacyl-CoA Dehydrogenase Deficiency Involves Activation of Glutamate Dehydrogenase

The mechanism of insulin dysregulation in children with hyperinsulinism associated with inactivating mutations of short-chain 3-hydroxyacyl-CoA dehydrogenase (SCHAD) was examined in mice with a knock-out of the hadh gene (hadh^−/−). The hadh^−/− mice had reduced levels of plasma glucose and elevated plasma insulin levels, similar to children with SCHAD deficiency. hadh^−/− mice were hypersensitive to oral amino acid with decrease of glucose level and elevation of insulin. Hypersensitivity to oral amino acid in hadh^−/− mice can be explained by abnormal insulin responses to a physiological mixture of amino acids and increased sensitivity to leucine stimulation in isolated perifused islets. Measurement of cytosolic calcium showed normal basal levels and abnormal responses to amino acids in hadh^−/− islets. Leucine, glutamine, and alanine are responsible for amino acid hypersensitivity in islets. hadh^−/− islets have lower intracellular glutamate and aspartate levels, and this decrease can be prevented by high glucose. hadh^−/− islets also have increased [U-¹⁴C]glutamine oxidation. In contrast, hadh^−/− mice have similar glucose tolerance and insulin sensitivity compared with controls. Perifused hadh^−/− islets showed no differences from controls in response to glucose-stimulated insulin secretion, even with addition of either a medium-chain fatty acid (octanoate) or a long-chain fatty acid (palmitate). Pull-down experiments with SCHAD, anti-SCHAD, or anti-GDH antibodies showed protein-protein interactions between SCHAD and GDH. GDH enzyme kinetics of hadh^−/− islets showed an increase in GDH affinity for its substrate, α-ketoglutarate. These studies indicate that SCHAD deficiency causes hyperinsulinism by activation of GDH via loss of inhibitory regulation of GDH by SCHAD.     

Sink-stimulated photosynthesis, increased transpiration and increased demand-dependent stimulation of nitrate uptake: nitrogen and carbon relations in the parasitic association Cuscuta reflexa-Coleus blumei

When parasitizing Coleus blumei Benth., grown in quartz sandculture and fed with 0.2, 1 or 5 mM nitrate, the biomass productionof Cuscuta reflexa Roxb. was inhibited to a similar extent asthat of the host supplied limiting concentrations of nitrate.In the presence of Cuscuta the growth and dry matter increaseof the host plant was severely inhibited. However, dry matterproduction of host plus parasite was only slightly less thanor at 0.2 mM nitrate almost the same as that of uninfected Coleusplants. Under all conditions of nitrate nutrition, parasitismby Cuscuta led to a substantial increase in photosynthesis inhost leaves under light-saturating conditions and in transpiration.Particularly with 0.2 mM and mM     

Respiratory mechanics following chronic cigarette smoke exposure in the Apoe $$^{-/-}$$ mouse model

Biomechanics and Modeling in Mechanobiology - Even though cigarette smoking (CS) has been on the decline over the past 50 years, it is still the leading cause of preventable premature death in the...     

Occurrence of cestodes and comparative efficacy of Typha angustata and sulphadimidine against cestodes in Columba livia domestica (Domestic Pigeon)

The occurrence of intestinal parasites of Columba livia domestica has been on the increase, leading to high economic and production losses with more fatal cases. This study was designed to investigate the prevalence of cestodes in pigeons and determine the efficacy of Typha angustata extract and sulphadimidine against these cestodes in the domestic pigeon. A total of 30 pigeons were examined. 18 (60%) pigeons were found infected with only one type of cestode species (Raillietina spp.). The difference in prevalence between males and females was statistically significant (χ² = 8.167, p = 0.004). The mean EPG count in group A (treated with T. angustata extract) before treatment and after treatment was 176 ± 4.33 and 155 ± 4.24, respectively. In group B (treated with sulphadimidine), the mean EPG calculated before treatment and after treatment was 184 ± 6.74 and 35 ± 3.53, respectively. The efficacy at day 28 of T. angustata and Sulphadimidine was 11.93% and 80.97%, respectively. It was concluded on the basis of the EPG and efficacy data that T. angustata extract had low efficacy against raillietiniasis, while as sulphadimidine, which is also used before to treat different intestinal parasites, had a good efficacy against raillietiniasis. Further studies are required to know the prevalence of other gastrointestinal parasites in pigeons and efficacy of different medicinal plants against such parasites.     

Rapid synthesis of 4-benzylidene and 4-[bis-(4-methoxyphenyl)-methylene-2-substituted phenyl-benzopyrans as potential selective estrogen receptor modulators (SERMs) using McMurry coupling reaction

7-Methoxy-4-(4-methoxybenzylidene)-2-substituted phenyl-benzopyrans I and 4-[bis-(4-methoxyphenyl)-methylene-2-substituted phenyl-benzopyrans II carrying different alkylamino residues, designed as estrogen receptor (ER) binding ligands, were successfully synthesized through the McMurry coupling reaction of substituted benzaldehyde/substituted benzophenones and 2-hydroxyphenyl-7-methoxy-chroman-4-one in presence of lithium aluminum hydride and titanium (IV) chloride (LAH-TiCl(4)). Self-coupling of carbonyl reactants led to the formation of several side products. The prototypes were evaluated for their relative binding affinity (RBA), as well as their estrogenic and antiestrogenic activities. High order of estrogenic activity (>50% gain) observed with compounds 3, 7a, 7b, 7c, 8, and 10a and also their partial estrogen antagonistic activity (> or =15%) at the uterine level points toward successful designing of the compounds. Compounds 4, 7a, 7b, 7c, and 10a also possessed significant anticancer activity against human adenocarcinoma cell line (MCF-7 cell line) that may be related to their estrogen-dependent action.     

Amide derivatives of 9,11-seco-estra-1,3,5(10)-trien-11-oic acid as modified orally active estrogen agonists with moderate antagonistic activity

Synthesis of amide derivatives of 9,11-seco-estra-1,3,5(10)-trien-11-oic acid containing alkyl and aromatic amine residues has been carried out with an aim to prepare orally active estrogen antagonists. Modification of the estradiol molecule in the form of C-seco-amide derivatives has led to their high oral absorption. Compounds 7 an n-propyl amide, 8 an n-butyl amide, and 16 a p-anisidyl amide of C-seco-estrane showed significant estrogen antagonistic activity (>20%), while, the majority of compounds possessed high estrogen agonistic activity on oral administration at 10mg/kg dose in rats.     

Variation in alphoid DNA size and trisomy 21: a possible cause of nondisjunction

The cause of nondisjunction of chromosome 21 remains largely unknown. In the present report, we investigate the hypothesis that variation in alphoid DNA size has a role in trisomy formation. Pulsed-field gel electrophoresis was used to examine the chromosome 21 alphoid DNA array lengths in 23 families (all of Northern European ancestry) with an affected child with trisomy 21 in whom the parental and meiotic origin of nondisjunction had been determined as maternal meiosis I, and in 38 controls. Initially, the combined alphoid size of both chromosome 21 homologues was assessed. This indicated an association between small combined alphoid size and maternal meiosis I nondisjunction. Moreover, in a subset of the families under study (n=12), it was possible to study the alpha21-I size of individual chromosome 21 homologues (simple alphoid size); this provided further evidence that the risk for nondisjunction is related to the size of the alphoid array of one of the two chromosome 21 homologues being small.     

Effect of Active Site Pocket Structure Modification of <Emphasis Type="SmallCaps">d</Emphasis>-Stereospecific Amidohydrolase on the Recognition of Stereospecific and Hydrophobic Substrates

d-Stereospecific amidohydrolase (DAH) from Streptomyces sp. 82F2 has potential utility for the synthesis of d/l configuration dipeptides by an aminolysis reaction. Structural comparison of DAH with substrate-bound d-amino acid amidase revealed that three residues located in the active site pocket of DAH (Thr145, Ala267, and Gly271) might be involved in interactions with d-phenylalanine substrate. We substituted Ala267 and Gly271, which are located at the bottom of the hydrophobic pocket of DAH, with Phe and observed changes in the stereoselectivity and specific activity toward the free and acetylated forms of d/l-Phe-methyl esters. In contrast, the mutation of Thr145, which likely supplies negative charge for recognition of the amino group of the substrate, hardly affected the stereoselectivity of the enzyme. A similar effect was observed in an investigation of hydrolysis and aminolysis reactions using the acetylated forms of d/l-Phe-methyl esters and 1,8-diaminooctane as an acyl-donor and acyl-acceptor, respectively. Substrate binding by DAH was disrupted by the mutation of Ala267 to Val or Trp and kinetic analysis showed that the hydrophobicity of the bottom of the active site pocket (Ala267 and Gly271) is important for both stereoselectivity and recognition of hydrophobic substrates.     

Influences on Trimerization and Aggregation of Soluble,Cleaved HIV-1 SOSIP Envelope Glycoprotein

We describe methods to improve the properties of soluble, cleaved gp140 trimers of the human immunodeficiency virus type 1 (HIV-1) envelope glycoproteins (Env) for use in structural studies and as immunogens. In the absence of nonionic detergents, gp140 of the KNH1144 genotype, terminating at residue 681 in gp41 (SOSIP.681), has a tendency to form higher-order complexes or aggregates, which is particularly undesirable for structure-based research. We found that this aggregation in the absence of detergent does not involve the V1, V2, or V3 variable regions of gp120. Moreover, we observed that detergent forms micelles around the membrane-proximal external region (MPER) of the SOSIP.681 gp140 trimers, whereas deletion of most of the MPER residues by terminating the gp140 at residue 664 (SOSIP.664) prevented the aggregation that otherwise occurs in SOSIP.681 in the absence of detergent. Although the MPER can contribute to trimer formation, truncation of most of it only modestly reduced trimerization and lacked global adverse effects on antigenicity. Thus, the MPER deletion minimally influenced the kinetics of the binding of soluble CD4 and a CD4-binding site antibody to immobilized trimers, as detected by surface plasmon resonance. Furthermore, the MPER deletion did not alter the overall three-dimensional structure of the trimers, as viewed by negative-stain electron microscopy. Homogeneous and aggregate-free MPER-truncated SOSIP Env trimers are therefore useful for immunogenicity and structural studies.