Dietary caffeine intake and bone status of postmenopausal women

Dietary caffeine intake has been suggested as a risk factor for bone loss in postmenopausal women. We measured the bone density of both hips and the total body in 138 healthy, postmenopausal women aged 55-70 y who had either never used hormone replacement therapy (HRT) or had used HRT for < 1 y. In this cross-sectional study, participants were stratified according to their reported current and long-time caffeinated beverage use into one of three groups: low [0-2 cups (180 mL, or 6 oz per cup) caffeinated coffee per day], moderate (3-4 cups caffeinated coffee per day), or high (> or = 5 cups caffeinated coffee per day). Caffeine intake was measured from diet records and by gas chromatography of each subject's brewed, caffeinated beverages. No association between caffeine intake and any bone measurement was observed. The anthropometric and nutrient intakes of the three groups were similar. Compared with caffeine intake based on chemical analysis of brewed beverages, 3-d prospective food records and computer-assisted analysis overestimated caffeine intake by nearly two-thirds. In conclusion, the habitual dietary caffeine intake of this cohort of 138 postmenopausal women ranged from 0-1400 mg/d and was not associated with total body or hip bone mineral density measurements. This study does not support the notion that caffeine is a risk factor for bone loss in healthy postmenopausal women.     

Further studies on the recoupling effect of 6-ketocholestanol upon oxidative phosphorylation in uncoupled liver mitochondria

The effect of 6-ketocholestanol was studied on CCCP-induced uncoupling in liver mitochondria, submitochondrial particles and cytochrome oxidase proteoliposomes. It was found that 6-ketocholestanol prevents and reverses uncoupling induced by nM concentrations of CCCP on the three systems assayed. As it was reported on kidney mitochondrial membranes [Chavez et al. (1996) FEBS Lett. 379, 305-308], the recoupling effect caused by 6-ketocholestanol on submitochondrial particles and proteoliposomes could be due to a diminution of membrane fluidity.     

Cellular sites for activation of delta-opioid receptors in the rat nucleus accumbens shell: relationship with Met5-enkephalin

The shell compartment of the nucleus accumbens (AcbSh) is prominently involved in the rewarding aspects of delta-opioid receptor (DOR) agonists, including one of its putative endogenous ligands, Met5-enkephalin (Enk). We examined the ultrastructural immunocytochemical localization of an antipeptide DOR antiserum and an antibody against Enk to determine the major cellular sites for DOR activation and the spatial relationship between DOR and Enk in this region. Sixty percent of DOR-immunoreactive profiles were axon terminals and small unmyelinated axons, whereas the remainder were mainly dendrites and dendritic spines. In axons and terminals, DOR labeling was distributed along plasma and vesicular membranes. DOR-containing terminals were mainly large and primarily formed symmetric synapses or occasionally asymmetric synapses. DOR immunoreactivity also was associated with terminals that were small and formed punctate symmetric or nonrecognizable synapses. Dual immunoperoxidase and immunogold labeling showed that 35% of DOR-labeled axons apposed other terminals that contained Enk. In addition, 25% of the DOR-labeled terminals contained Enk. Thirty-five percent of DOR labeling was observed within dendrites and dendritic spines. DOR-labeled spines showed intense immunoreactivity within asymmetric postsynaptic junctions, which were formed by terminals that lacked Enk immunoreactivity. DOR-labeled spines, however, were apposed to Enk-containing terminals in 13% of all associations between dually labeled profiles. These results provide ultrastructural evidence that activation of DOR in the AcbSh is primarily involved in modulating the presynaptic release of mainly inhibitory, but also excitatory, neurotransmitters. These data also suggest that DOR plays a role in determining the postsynaptic response to excitatory afferents.     

The surgical treatment of aneurysms of the abdominal aorta

The sputum specimens from 1363 patients at the age of 16 to 65 years with nonspecific pulmonary diseases and the pleural exudate specimens from 325 patients were tested for fungi in 1989-1994. The etiological significance of Candida was stated at a concentration of > 10(5) GFU per 1 ml of the sputum. The identification was performed by the routine methods. An increase in the rate of the fungi isolation was studied in the time course of the observation: 15.3 +/- 1.9 per cent in 1989 and 31.6 +/- 3.4 per cent in 1994. The fungi were more frequently isolated from the patients with lung abscesses (38.0 +/- 4.1 per cent of the cases). In the patients with pyothorax the fungi were isolated from the pleural exudate specimens only in 6.8 +/- 1.4 per cent of the cases. The groups of risk of the susceptibility to Candida were revealed. They included patients at the age of 21 to 30 years and above 60. Out of 484 Candida isolates 80.7 per cent belonged to C. albicans, 4.2 per cent to C. tropicalis, 2.1 per cent to C. kefyr and 1.8 per cent to C. krusei. The isolates of C. parapsilosis, C. guillermoudii, C. utilis and C. brumptii were rate. The isolates were highly susceptible to nystatin (91,8 per cent) and lowly susceptible to levorin (35.4 per cent), amphoglucamine (24.7 per cent) and ketokonazol (16.8 per cent).     

Gene sequences of the pcpB gene of pentachlorophenol-degrading Sphingomonas chlorophenolica found in nondegrading bacteria

An optically active, rigid rodlike helical polysilane with 6, 9, 12-trioxatetradecyl and (S)-2-methylbutyl substituents (1) was newly obtained as a very high molecular weight polymer of several million. Due to the presence of trietheral substituent, 1 was readily soluble in a polar solvent such as ethanol and a mixture of ethanol and water, but was insoluble in pure water. Polysilane 1 in pure ethanol at room temperature exhibited an intense and narrow ultraviolet (UV) and circular dichroism (CD) absorptions at 323 nm, associated with an almost mirror imaged fluorescence (FL) at 328 nm, that are characteristics of rigid rodlike, single-screw-sense helical polysilanes reported previously. When solution temperature was changed from 60 degrees C to -104 degrees C, a global shape of 1 expanded associated with an increase of segment length, whereas a screw pitch tended to be wound tightly. On the other hand, as a solvent polarity became poor, a global shape of 1 shrunk associated with an decrease of segment length and formed a chiral motif with an M-helicity between two helical segments with a kink. At a ratio of 50% of ethanol/water of 50:50 (v/v), 1 became insoluble and formed aggregates.     

Arrangement of rhodopsin transmembrane alpha-helices

Rhodopsins, the photoreceptors in rod cells, are G-protein-coupled receptors with seven hydrophobic segments containing characteristic conserved sequence patterns that define a large family. Members of the family are expected to share a conserved transmembrane structure. Direct evidence for the arrangement of seven alpha-helices was obtained from a 9A projection map of bovine rhodopsin. Structural constraints inferred from a comparison of G-protein-coupled receptor sequences were used to assign the seven hydrophobic stretches in the sequence to features in the projection map. A low-resolution three-dimensional structure of bovine rhodopsin and two projection structures of frog rhodopsin confirmed the position of the three least tilted helices, 4, 6 and 7. A more elongated peak of density for helix 5 indicated that it is tilted or bent, but helices 1, 2 and 3 were not resolved. Here we have used electron micrographs of frozen-hydrated two-dimensional frog rhodopsin crystals to determine the structure of frog rhodopsin. Seven rods of density in the map are used to estimate tilt angles for the seven helices. Density visible on the extracellular side of the membrane suggests a folded domain. Density extends from helix 6 on the intracellular side, and a short connection between helices 1 and 2, and possibly a part of the carboxy terminus, are visible.     

Role of calcineurin in Ca2+-induced release of catecholamines and neuropeptides

Neurotransmission requires rapid docking, fusion, and recycling of neurotransmitter vesicles. Several of the proteins involved in this complex Ca2+-regulated mechanism have been identified as substrates for protein kinases and phosphatases, e.g., the synapsins, synaptotagmin, rabphilin3A, synaptobrevin, munc18, MARCKS, dynamin I, and B-50/GAP-43. So far most attention has focused on the role of kinases in the release processes, but recent evidence indicates that phosphatases may be as important. Therefore, we investigated the role of the Ca2+/calmodulin-dependent protein phosphatase calcineurin in exocytosis and subsequent vesicle recycling. Calcineurin-neutralizing antibodies, which blocked dynamin I dephosphorylation by endogenous synaptosomal calcineurin activity, but had no effect on the activity of protein phosphatases 1 or 2A, were introduced into rat permeabilized nerve terminals and inhibited Ca2+-induced release of [3H]noradrenaline and neuropeptide cholecystokinin-8 in a specific and concentration-dependent manner. Our data show that the Ca2+/calmodulin-dependent phosphatase calcineurin plays an essential role in exocytosis and/or vesicle recycling of noradrenaline and cholecystokinin-8, transmitters stored in large dense-cored vesicles.