The effects of O- and N-linked glycosylation on the secretion and bile salt-stimulation of pancreatic carboxyl ester lipase activity

The immune status of 29 members of the Australian National Antarctic Research Expeditions (ANARE) was investigated before, during, and after a 56 day summer voyage to Antarctica and correlated with psychological and physiological parameters. All subjects were healthy. Expedition personnel demonstrated decreased cell mediated immune responses (CMI) assessed by the CMI Multi-test; 21% were hypoergic. The major associated observation was a significant negative correlation with anxiety in Antarctica. However, perceived anxiety was greater before and after the voyage. No significant changes were found in T and B lymphocyte subsets, immunoglobulin and complement components and cutaneous blood flow, nor was there any clinical evidence of illness. Of the hormones examined only cortisol was low predeparture which may reflect increased perceived anxiety at that time. Changes in immune control mechanism were apparent as shown by reduced CMI responses and lowered tetanus antibody levels. Stress factors are postulated to induce depression of the immune response in Antarctica. The association with anxiety suggests that brain peptides or associated cytokines may have a role in mediating these immune events. Such alterations in immune status have implications for health management in isolated and extreme conditions.     

Platinum-catalyzed enzyme electrodes immobilized on gold using self-assembled layers

The bonding of enzymes to self-assembled monolayers (SAMs) of alkanethiols onto gold electrode surfaces is exploited to produce an enzyme biosensor. The attachment of glucose oxidase to a SAM of 3-mercaptopropionic acid was achieved using carbodiimide coupling. The resultant biosensor showed good sensitivity to glucose and a large dynamic range when measured amperometrically via the p-benzoquinone mediator. On the other hand, subsequent platinization of the enzyme-SAM electrode allowed hydrogen peroxide produced in the enzyme reaction to be detected directly, thus obviating the need for an artificial redox mediator. The performance of such sensors constructed on bulk gold electrodes was evaluated and finally compared to that of some preliminary thin-film gold electrodes. Biosensors constructed using the two alternative electrode surfaces have quite different sensitivities, thus reflecting the influence of the anchoring surface on the performance of the biosensor.     

Pilot evaluation of venlafaxine hydrochloride for the therapy of hot flashes in cancer survivors

PURPOSE: Hot flashes can be a prominent clinical problem for breast cancer survivors and men who undergo androgen-deprivation therapy. Anecdotal information suggested a low dose of a relatively new antidepressant, venlafaxine, could abrogate this clinical problem. MATERIALS AND METHODS: This study included 28 consecutive assessable patients entered onto a phase II clinical trial. Hot flash data were collected by daily diary questionnaires during a 1-week baseline period and then for 4 weeks, during which time patients received venlafaxine 12.5 mg orally twice daily. RESULTS: Fifty-eight percent of patients who completed the study had a greater than 50% reduction in hot flash scores (frequency times severity) during the fourth treatment week as compared with the baseline week. Median weekly hot flash scores were reduced by 55% from baseline during the fourth week of venlafaxine therapy. Therapy was generally well tolerated and appeared to alleviate fatigue, sweating, and trouble sleeping. CONCLUSION: Venlafoxine appears to represent an efficacious new method to alleviate hot flashes. Further evaluation of this compound for alleviating hot flashes is indicated.     

Pemoline hepatotoxicity in children

Pemoline hepatotoxicity ranges from asymptomatic elevations in levels of serum aminotransferases to fulminant liver failure. We report five cases of pemoline hepatotoxicity in children (four boys, one girl), including the only reported case resulting in orthotopic liver transplantation. We conclude that pemoline causes toxic liver damage in children. The severity of the damage is highly variable, and its onset may be late in the course of treatment. Pemoline and methylphenidate may act synergistically to cause liver damage. The levels of serum aminotransferases should be monitored throughout treatment with these agents.     

Local calcium signalling by inositol-1,4,5-trisphosphate in Purkinje cell dendrites

The second messenger inositol-1,4,5-trisphosphate (InsP3) releases Ca2+ from intracellular Ca2+ stores by activating specific receptors on the membranes of these stores. In many cells, InsP3 is a global signalling molecule that liberates Ca2+ throughout the cytoplasm. However, in neurons the situation might be different, because synaptic activity may produce InsP3 at discrete locations. Here we characterize InsP3 signalling in postsynaptic cerebellar Purkinje neurons, which have a high level of InsP3 receptors. We find that repetitive activation of the synapse between parallel fibres and Purkinje cells causes InsP3-mediated Ca2+ release in the Purkinje cells. This Ca2+ release is restricted to individual postsynaptic spines, where both metabotropic glutamate receptors and InsP3 receptors are located, or to multiple spines and adjacent dendritic shafts. Focal photolysis of caged InsP3 in Purkinje cell dendrites also produces Ca2+ signals that spread only a few micrometres from the site of InsP3 production. Uncaged InsP3 produces a long-lasting depression of parallel-fibre synaptic transmission that is limited to synapses where the Ca2+ concentration is raised. Thus, in Purkinje cells InP3 acts within a restricted spatial range that allows it to regulate the function of local groups of parallel-fibre synapses.     

Regulation of glutamine:fructose-6-phosphate amidotransferase by cAMP-dependent protein kinase

Glutamine:fructose-6-phosphate amidotransferase (GFA) is the rate-limiting enzyme in hexosamine biosynthesis, an important pathway for cellular glucose sensing. Human GFA has two potential sites for phosphorylation by cAMP-dependent protein kinase A (PKA). To test whether GFA activity is regulated by cAMP-dependent phosphorylation, rat aortic smooth muscle cells were treated in vivo with cAMP-elevating agents, 10 micromol/l forskolin, 1 mmol/l 8-Br-cAMP, or 3-isobutyl-1-methylxanthine. All treatments resulted in rapid and significant increases (2- to 2.4-fold) in GFA activity assayed in cytosolic extracts. Maximal effects of forskolin were observed at 10 micromol/l and 60 min. Preincubation of cells with cycloheximide did not abolish the effect of forskolin. Incubation of cytosolic extracts at 37 degrees C for 10 min in a buffer without phosphatase inhibitors led to a 79% decrease of GFA activity. This loss of activity was inhibited by the addition of phosphatase inhibitors (5 mmol/l sodium orthovanadate, 50 mmol/l sodium fluoride, or 5 mmol/l EDTA, but not 100 nmol/l okadaic acid), suggesting that GFA undergoes rapid dephosphorylation by endogenous phosphatases. Purified GFA is phosphorylated in vitro by purified PKA, resulting in a 1.7-fold increase in GFA activity. Treatment of GFA with purified protein kinase C had no effect. We conclude that GFA activity may be modulated by cAMP-dependent phosphorylation.