Ovulation pattern in successive cycles in the baboon

The purpose of this study was to determine if the selection of the side on which ovulation occurs in successive cycles is a random event. Forty-seven baboons were observed for four consecutive cycles and 37 for two to three consecutive cycles. Side of ovulation was determined by laparoscopic examination. Of the 286 cycles studied, 146 cycles (51 %) showed ovulations on the left side and 140 cycles (49 %) on the right. Analysis of the data using two consecutive ovulations in 286 cycles revealed that the selection of the side of ovulation is a random event. However, when four consecutive ovulations observed in 47 baboons were analyzed, it was found that the observed pattern of ovulation was different from that expected from random chance (p>0.05). There are 16 possible combinations in a sequence of four ovulations. Eight of 47 baboons (17 %) ovulated on the same side for four consecutive cycles, 15 baboons (32 %) ovulated three times on the same side for four ovulations, and 24 baboons (51 %) showed two ovulations on each side. Alternation of ovulation in a sequence of four consecutive ovulations was observed 48 times (25.5 %) and alternation of ovulation in two consecutive cycles was observed 106 times (51 %).     

Effects of taxol and nocodazole on insulin secretion from isolated rat islets of Langerhans

Taxol, a promotor of microtubule polymerization, and nocodazole, which induces microtubule depolymerization, used at concentrations known to be specific for these effects in other cell types, were each shown to inhibit glucose-stimulated insulin secretion from isolated rat islets of Langerhans. These findings suggest that the dynamic regulation of microtubule polymerization-depolymerization in pancreatic B ceils may be important for insulin secretion via the microtubule-microfilamentous system.     

Azide promotion of alkane oxidations catalyzed by metal complexes in solution

The oxidation of light alkanes catalyzed by metal complexes in solution is promoted by Group 1 metal azides. Yields of oxygenated reaction products are greatly enhanced when catalytic amounts of azides are added to the reaction mixture. The addition of sodium azide to oxidations catalyzed by transition metal acetylacetonates, heteropolyacids, polyoxometallates, phthalocyanines, bis-(pyridylimino)isoindolines, porphyrins and Schiff bases significantly enhances rates of low-temperature catalytic oxidation reactions in the liquid phase. Earlier work showed that Cr(III), Mn(III), Fe(III) and Co(III) complexes of electron-deficient macrocyclic complexes exhibited remarkable catalytic activity for oxidizing light alkanes. Such complexes bearing axial azide ligands were far more active than their axial chloride or acelate counterparts.     

Biochemical characterization, stability studies and N-terminal sequence of a bi-functional inhibitor from Phaseolus aureus Roxb. (Mung bean)

Herein, we report the purification and biochemical characterization of a novel bi-functional protein proteinase/amylase inhibitor from the dietary leguminous pulse Phaseolus aureus Roxb. (Vigna radiata L.) by means of acetic acid precipitation, salt fractionation, ion-exchange chromatography (DEAE-cellulose) and affinity chromatography on trypsin-sepharose column. P. aureus inhibitor is a bi-functional inhibitor since it exhibits inhibitory activity towards trypsin-like and alpha-chymotrypsin-like serine proteinases as well as against alpha-amylases. It is a helix-rich protein (Mr 13,600) containing approximately eight tyrosines, one tryptophan and two cystines. N-terminal sequence alignment reveals no homology to other proteinase inhibitors reported from Phaseolus sp. thereby confirming that it is a novel inhibitor. Inhibitory activity measurements show that the inhibitor is quite stable even at extremely high temperatures and is only slightly affected by pH changes. Circular dichroism (CD) conformational studies revealed some changes in its near- as well as far-ultraviolet spectrum at extremes of pH and temperature. Treatments with trypsin for varying time periods did not alter its proteolytic inhibitory activity but caused some reduction in its amylase inhibitory activity.     

Fish oil increases raft size and membrane order of B cells accompanied by differential effects on function

Fish oil (FO) targets lipid microdomain organization to suppress T-cell and macrophage function; however, little is known about this relationship with B cells, especially at the animal level. We previously established that a high FO dose diminished mouse B-cell lipid raft microdomain clustering induced by cross-linking GM1. To establish relevance, here we tested a FO dose modeling human intake on B-cell raft organization relative to a control. Biochemical analysis revealed more docosahexaenoic acid (DHA) incorporated into phosphatidylcholines than phosphatidylethanolamines of detergent-resistant membranes, consistent with supporting studies with model membranes. Subsequent imaging experiments demonstrated that FO increased raft size, GM1 expression, and membrane order upon cross-linking GM1 relative to no cross-linking. Comparative in vitro studies showed some biochemical differences from in vivo measurements but overall revealed that DHA, but not eicosapentaenoic acid (EPA), increased membrane order. Finally, we tested the hypothesis that disrupting rafts with FO would suppress B-cell responses ex vivo. FO enhanced LPS-induced B-cell activation but suppressed B-cell stimulation of transgenic naive CD4(+) T cells. Altogether, our studies with B cells support an emerging model that FO increases raft size and membrane order accompanied by functional changes; furthermore, the results highlight differences in EPA and DHA bioactivity.     

Defective protein folding and intracellular retention of thyroglobulin-R19K mutant as a cause of human congenital goiter

It has been suggested that a thyroglobulin (Tg)-R19K missense mutation may be a newly identified cause of human congenital goiter, which is surprising for this seemingly conservative substitution. Here, we have examined the intracellular fate of recombinant mutant Tg expressed in COS-7 cells. Incorporation of the R19K mutation largely blocked Tg secretion, and this mutant was approximately 90% degraded intracellularly over a 24-h period after synthesis. Before its degradation, the Tg-R19K mutant exhibited abnormally increased association with molecular chaperones BiP, calnexin, and protein disulfide isomerase, and was unable to undergo anterograde advance from the endoplasmic reticulum (ER) through the Golgi complex. Inhibitors of proteasomal proteolysis and ER mannosidase-I both prevented ER-associated degradation of the Tg-R19K mutant and increased its association with ER molecular chaperones. ER quality control around Tg residue 19 is not dependent upon charge but upon side-chain packing, because Tg-R19Q was efficiently secreted. Whereas a Tg mutant truncated after residue 174 folds sufficiently well to escape ER quality control, introduction of the R19K point mutation blocked its secretion. The data indicate that the R19K mutation induces local misfolding in the amino-terminal domain of Tg that has global effects on Tg transport and thyroid hormonogenesis.