Monitoring for clenbuterol abuse in N Ireland 1989-1994

Laboratory testing in N. Ireland for the illegal growth promoting agent, clenbuterol (CBL), is centralized at the Veterinary Sciences Division, Belfast. During the past 6 years a variety of testing schemes have evolved to determine the level of abuse of this drug in the local meat industry.

Association of the G4 rotavirus genotype with gastroenteritis in adults

Rotavirus is the most common etiological cause of acute viral gastroenteritis in infants and young children worldwide, yet its role in the adult population is less well understood. We have recently identified rotavirus as the causative agent of severe diarrhea in adults, specifically in two gastroenteritis outbreaks in separate care for the elderly homes. Strain typing has shown the continued presence of P[8]G1, the emergence of P[8]G9, and the reemergence of P[8]G4. A total of 26 community cases and 6 outbreak cases of rotavirus infection, positive via a molecular screening assay, were subsequently amplified using VP4 and VP7 specific primers (Con2/Con3 and 1A/1B primer sets, respectively). The age range of patients investigated was from

Deletion of Gremlin1 increases cell proliferation and migration responses in mouse embryonic fibroblasts

Gremlin1 (Grem1) is an antagonist of bone morphogenetic proteins (BMPs) that plays a critical role in embryonic and postnatal development. Grem1 has been implicated as both a promoter and an inhibitor of cell proliferation driven by BMP-4 and other mitogens in a diverse range of cell types. Recent data showed that Grem1 can trigger angiogenesis via vascular endothelial growth factor receptor (VEGFR2) binding, highlighting that the precise modalities of Grem1 signalling require further elucidation.

Fetal Cardiac Effects of Maternal Hyperglycemia During Pregnancy

Maternal diabetes mellitus is associated with increased teratogenesis, which can occur in pregestational type 1 and type 2 diabetes. Cardiac defects and with neural tube defects are the most common malformations observed in fetuses of pregestational diabetic mothers. The exact mechanism by which diabetes exerts its teratogenic effects and induces embryonic malformations is unclear. Whereas the sequelae of maternal pregestational diabetes, such as modulating insulin levels, altered fat levels, and increased reactive oxygen species, may play a role in fetal damage during diabetic pregnancy, hyperglycemia is thought to be the primary teratogen, causing particularly adverse effects on cardiovascular development. Fetal cardiac defects are associated with raised maternal glycosylated hemoglobin levels and are up to five times more likely in infants of mothers with pregestational diabetes compared with those without diabetes. The resulting anomalies are varied and include transposition of the great arteries, mitral and pulmonary atresia, double outlet of the right ventricle, tetralogy of Fallot, and fetal cardiomyopathy.

STIMULATION OF PHOSPHOLIPASE C-BETA(2) BY RECOMBINANT GUANINE-NUCLEOTIDE-BINDING PROTEIN BETA-GAMMA DIMERS PRODUCED IN A BACULOVIRUS/INSECT CELL EXPRESSION SYSTEM - REQUIREMENT OF GAMMA-SUBUNIT ISOPRENYLATION FOR STIMULATION OF PHOSPHOLIPASE-C

Recombinant wild-type beta(1) gamma(1) dimers of signal-transducing guanine nucleotide-binding proteins (G proteins) and beta(1) gamma 1 dimers carrying a mutation known to block gamma-subunit isoprenylation (beta(1) gamma(1)C71S) were expressed in baculovirus-infected insect cells. Both wild-type and mutant beta(1) gamma(1) dimers were found in soluble fractions of infected cells upon subcellular fractionation. Anion exchange chromatographic and metabolic-radiolabeling studies revealed that the soluble beta(1) gamma(1) preparation contained approximately equal amounts of non-isoprenylated and isoprenylated beta(1) gamma(1) dimers. Soluble wild-type and mutant beta(1) gamma(1) dimers and native beta(1) gamma(1) dimers purified from bovine retina were reconstituted with recombinant phospholipase C-beta(2). Only isoprenylated beta(1) gamma(1) dimers were capable of stimulating phospholipase C-beta(2). The results show that gamma-subunit isoprenylation and/or additional post-translational processing of the protein are required for beta gamma subunit stimulation of phospholipase C.

Isoprenylation of the G protein gamma subunit is both necessary and sufficient for beta gamma dimer-mediated stimulation of phospholipase C

We have previously shown that isoprenylation and/or additional pest-translational processing of the G protein gamma(1) subunit carboxyl terminus is required for beta(1) gamma(1) subunit stimulation of phospholipase C-beta(2) (PLC beta(2)) [Dietrich, A., Meister, M., Brazil, D., Camps, M., & Gierschik, P. (1994) Eur. J. Biochem. 219, 171-178]. To examine whether isoprenylation of the gamma(1) subunit alone is sufficient for beta(1) gamma(1)-mediated PLC beta(2) stimulation or whether any of the two subsequent modifications, proteolytic removal of the carboxyl-terminal tripeptide and/or carboxylmethylation, is required for this effect, nonisoprenylated recombinant beta(1) gamma(1) dimers were produced in baculovirus-infected insect cells, purified to near homogeneity, and then isoprenylated in vitro using purified recombinant protein farnesyltransferase. Analysis of the beta(1) gamma(1) dimer after in vitro farnesylation by reversed phase high-performance liquid chromatography followed by delayed extraction matrix-assisted laser desorption/ionization mass spectrometry confirmed that the gamma(1) subunit was carboxyl-terminally farnesylated but not proteolyzed and carboxylmethylated. Functional reconstitution of in vitro-farnesylated beta(1) gamma(1) dimers with a recombinant PLC beta(2) isozyme revealed that farnesylation rendered recombinant nonisoprenylated beta(1) gamma(1) dimers capable of stimulating PLC beta(2) and that the degree of this stimulation was only approximately 45% lower for in vitro-farnesylated beta(1) gamma(1) dimers than for fully modified native beta(1) gamma(1) purified from bovine retinal rod outer segments. Taken together, these results suggest that isoprenylation of the gamma subunit is both necessary and sufficient for beta gamma dimer-mediated stimulation of phospholipase C.

On the mechanism of the inhibition of transducin function by farnesylcysteine analogs

The gamma subunits of heterotrimeric G proteins are isoprenylated/methylated on their carboxy termini. The photoreceptor G protein, transducin, is farnesylated/methylated at this position. Since the isoprenyl group is required for G protein function, it is of great interest to determine the mechanism by which the farnesyl group of T gamma interacts with the other transducin subunits and/or the activated photoreceptor, rhodopsin. Farnesylcysteine derivatives (N-acetyl-S-farnesyl-L-cysteine and farnesylated peptides) have been previously shown to have effects on transducin activity at high concentrations. Here, an extensive survey is done of farnesylcysteine analogs and other lipid molecules, which are tested for their ability to inhibit GTP/GDP exchange in transducin catalyzed by photolyzed rhodopsin. These studies are carried out to determine the nature of the inhibition process. While it does not appear that these molecules exhibit the specificity which would characterize a ligand-receptor type mechanism, the results suggest that these compounds are not acting in a nonspecific detergent-like manner either. The most likely mode of action of farnesylcysteine analogs is that they interfere with the lipid-lipid based association of T alpha and T beta gamma through the lipid modifications present on each subunit.

A role for the enteric nervous system in the response to helminth infections

The enteric nervous system (ENS) in the gut contains a particularly high concentration of nerve cells, and effectively functions as an independent 'minibrain'. Interactions between nerve, endocrine, immune and other cell types allow the sophisticated regulation of normal gut physiology. They can also bring about a co-ordinated response to parasitic infection, possibly leading to expulsion of the parasite. In this review, Derek McKay and Ian Fairweather will consider, in brief, data pertaining to changes in the ENS following intestinal helminth infections and speculate on the role that these alterations may have in the expulsion of the parasite burden and the putative ability of the parasite to modulate these events.

Chemoenzymatic formal synthesis of (-)- and (+)-epibatidine

The cis-dihydrocatechol, derived from enzymatic cis-dihydroxylation of bromobenzene using the microorganism Pseudomonas putida UV4, was converted into (-)-epibatidine in eleven steps with complete stereocontrol. In addition, an unprecedented palladium-catalysed disproportionation reaction gave the (+)-enantiomer of an advanced key intermediate employed in a previous synthesis of epibatidine.