Follicular vascularity--the predictive value of transvaginal power Doppler ultrasonography in an in-vitro fertilization programme: a preliminary study

The glnA gene from the human pathogen Streptococcus agalactiae was cloned from a genomic library prepared with the lambda phage vector lambdaDASHII. A 4.6-kb DNA fragment of one of the recombinant phages was subcloned in pUC18. This Escherichia coli clone expressed a 52-kDa protein encoded by a 1,341-bp open reading frame. The nucleotide sequence of the open reading frame and the deduced amino acid sequence shared a significant degree of homology with the sequences of other glutamine synthetases (GS). The highest homology was between our deduced protein and GS of gram-positive bacteria such as Bacillus subtilis, Bacillus cereus, and Staphylococcus aureus. Plasmids with the cloned streptococcal glnA were able to complement E. coli glnA mutants grown on minimal media. Rabbit antisera to streptococcal GS recombinant protein recognized not only the recombinant protein but also a similar-sized band in mutanolysin extracts of all group B streptococcal strains tested, regardless of polysaccharide type or surface protein profile. The amino acid sequence of the deduced protein had similarities to other streptococcal cell-surface-bound proteins. The possible functional role of the immunological features of streptococcal GS is discussed.     

Multifactorial analysis of lung cancer dose-response relationships for workers at the Mayak nuclear enterprise

Dose-response relationships for alpha-radiation-induced lung cancers (adenocarcinoma, squamous carcinoma and small cell carcinoma) were developed by multifactorial analysis using data for Mayak nuclear enterprise workers chronically exposed by inhalation to 239Pu. The three most important lung cancer risk factors (smoking, plutonium incorporation, and external gamma irradiation), out of six factors previously identified, were used. Relative risks (odds ratios) were determined for 500 nuclear enterprise workers (162 cancer cases, 338 control) for different dose levels using a case-control study design and logistic regression. A threshold at about 3.7 kBq or 0.80 Gy was discovered for incorporated plutonium, which is satisfactorily described by linear-quadratic and quadratic models. Excess relative risk was 0.020 kBq(-2) and 0.97 Gy(-2). This quadratic function was mainly due to adenocarcinoma. A trend for decreasing risk was noted for the lowest levels of plutonium incorporation, near permissible level. No clear-cut dose-response relationship for lung cancer induction by chronic external gamma irradiation was obtained. Lung cancer induction by cigarette smoking had a linear dependence: smoking of one pack of papiroses (a type of Russian cigarette) per day for 5 y increases the lung cancer risk twofold. The effect was most clearly manifested for squamous-cell carcinoma.     

Effect of increased afterload on cardiac lipoprotein lipase and VLDL receptor expression

Fatty acids are a major source of fuel for energy production by myocytes. Lipoprotein lipase (LPL) and very low density lipoprotein (VLDL) receptor are abundantly expressed by the heart and skeletal muscles. LPL and possibly VLDL receptor represent the primary route of access to fatty acids contained in circulating triglyceride-rich lipoproteins. Physical exercise and thyroid hormone, which promote energy consumption, upregulate LPL expression in skeletal muscles. This study tested the hypothesis that increased cardiac workload might modulate myocardial LPL and/or VLDL receptor expressions. Accordingly, cardiac tissue LPL activity, LPL and VLDL receptor proteins and mRNA abundance were studied in Sprague-Dawley rats 4 weeks after induction of severe thoracic aorta constriction or sham operation. Elevation of afterload with thoracic aortic constriction led to a significant cardiomegaly and a marked upregulation of cardiac LPL activity, LPL mRNA and LPL protein abundance, but did not modify VLDL receptor mRNA or protein abundance. Thus, increased cardiac workload in this model results in upregulation of myocardial LPL expression which can enhance fatty acid availability to accommodate the heart's increased energy requirement.     

Epidemiology of clonorchiasis in Ninh Binh Province, Vietnam

We present the spatial structure of binase, a small extracellular ribonuclease, derived from 1H-NMR* data in aqueous solution. The total of 20 structures were obtained via torsion angle dynamics using DYANA program with experimental NOE and hydrogen bond distance constraints and phi and chi1 dihedral angle constraints. The final structures were energy minimised with ECEPP/2 potential in FANTOM program. Binase consists of three alpha-helices in N-terminal part (residues 6-16, 26-32 and 41-44), five-stranded antiparallel beta-sheet in C-terminal part (residues 51-55, 70-75, 86-90, 94-99 and 104-108) and two-stranded parallel beta-sheet (residues 22-24 and 49-51). Three loops (residues 36-39, 56-67 and 76-83), which play significant role in biological functioning of binase, are flexible in solution. The differences between binase and barnase spatial structures in solution explain the differences in thermostability of binase, barnase and their hybrids.     

Inequivalence of the two tyrosine ligands in the N-lobe of human serum transferrin

Human serum transferrin N-lobe (hTF/2N) has four iron-binding ligands, including one histidine, one aspartate, and two tyrosines. The present report elucidates the inequivalence of the two tyrosine ligands (Tyr 95 and Tyr 188) on the metal-binding properties of hTF/2N by means of site-directed mutagenesis, metal release kinetics, and absorption and electron paramagnetic resonance (EPR) spectroscopies. When the liganding tyrosines were mutated individually to phenylalanine, the resulting mutant Y95F showed a weak binding affinity for iron and no affinity for copper, whereas, mutant Y188F completely lost the ability to bind iron but formed a stable complex with copper. Since other studies have demonstrated that mutations of the other two ligands, histidine and aspartate, did not completely abolish iron binding, the present findings suggest that the tyrosine ligand at position 188 is essential for binding of iron to occur. Replacement of Tyr 188 with phenylalanine created a favorable chemical environment for copper coordination but a fatal situation for iron binding. The positions of the two liganding tyrosines in the metal-binding cleft suggest a reason for the inequivalence.     

Novel phosphoserine phosphatase inhibitors

Phosphoserine phosphatase (EC 3.1.1.3) catalyzes the final step in the major pathway of L-serine biosynthesis in brain. This enzyme may also regulate the levels of glycine and D-serine, the known and putative co-agonists for the glycine site of the N-methyl-D-aspartate receptor in caudal and rostral brain regions, respectively. Using L-phosphoserine as substrate, the rank order potency for inhibition of phosphoserine phosphatase was p-chloromercuriphenylsulfonic acid (CMPSA) > glycerophosphorylcholine > hexadecylphosphocholine > or = phosphorylcholine > N-ethylmaleimide > or = L-serine > fluoride > D-2-amino-3-phosphonopropionic acid (D-AP3). Glycerylphosphorylcholine (IC50 18 microM) was found to be an uncompetitive inhibitor of phosphoserine phosphatase. Glycerylphosphorylcholine probably binds a novel site on the enzyme since the known allosteric inhibitor L-serine is highly selective for its feedback regulatory site, indicated by the inactivity of 25 L-serine analogs. Fluoride ion (IC50 770 microM) may bind the active site as has been shown for other Mg2+-dependent enzymes. The sulfhydryl reagent CMPSA is a potent, noncompetitive inhibitor of the enzyme using L-phosphoserine as substrate (IC50 9 microM) but is > 300-fold less potent using D-phosphoserine as substrate. Substrate-dependent differences are also observed with the sulfhydryl alkylator N-ethylmaleimide, which inhibits L-phosphoserine, but stimulates D-phosphoserine hydrolysis. These sulfhydryl reagents may dissociate multimeric forms of the enzyme to form monomers; the multimeric forms and monomers may preferentially cleave L- and D-phosphoserine, respectively. Phosphorylcholine esters and sulfhydryl reagents may prove useful in determining the contribution of phosphoserine phosphatase to the biosynthesis of glycine and D-serine in neuronal tissue in vitro.     

Prostate specific antigen in the expressed prostatic fluid of men with benign prostatic hyperplasia and prostate carcinoma

PURPOSE: We tested the hypothesis that the histochemically demonstrated prostate specific antigen (PSA) content of prostate carcinoma cells does not necessarily reflect PSA production and secretion by evaluating expressed prostatic fluid. MATERIALS AND METHODS: Expressed prostatic fluid and serum from 152 men with clinical benign prostatic hypertrophy (BPH), 132 with histologically proved BPH and 46 with prostate carcinoma were analyzed with the Hybritech PSA assay. RESULTS: Expressed prostatic fluid PSA levels from carcinoma patients (median 1.70 mg./ml., mean 2.25) were significantly higher than in the histologically proved BPH group (median 1.28 mg./ml., mean 1.42, p < 0.05). CONCLUSIONS: PSA concentration is increased in the expressed prostatic fluid of prostates of men with carcinoma compared to those with histological BPH. This finding may be a functional manifestation of a field change or paracrine effects within the prostate.