Transformation-derived Neisseria gonorrhoeae plasmids with altered structure and function.

Plasmid deoxyribonucleic acid from Neisseria gonorrhoeae containing a 7.1-kilobase (kb) (4.7-megadalton) penicillinase (Pcr) plasmid transformed homogenic gonococci to penicillinase production at a low frequency. About 25% of the penicillinase-producing gonococcal transformants contained Pcr plasmids which were either larger or smaller than the 7.1 kb donor plasmid; these Pcr plasmids varied in size from 3.45 to 42 kb. Some of these altered plasmids differed from the donor plasmid in stability or in frequency of mobilization by a 36-kb (24-megadalton) conjugative plasmid. A restriction endonuclease cleavage map of the 7.1-kilobase Pcr plasmid and several of the smaller deleted plasmids was constructed. The most common size of altered Pcr plasmid was 5.1 kb (3.4 megadaltons). A Pcr plasmid isolated from a gonococcus in London, England, was identical with these 5.1-kb transformant plasmids in both size and restriction endonuclease cleavage profiles, suggesting that the 5.1-kb Pcr plasmid could have arisen from a 7.1-kb Pcr plasmid by a transformation-associated deletion in nature.     

Demonstration of aromatic l-amino acid decarboxylase activity in human brain with l-dopa and l-5-hydroxytryptophan as substrates by high-performance liquid chromatography with electrochemical detection

The enzymatic decarboxylations of l-DOPA and l-5-hydroxytryptophan (l-5-HTP) by aromatic l-amino acid decarboxylase (AADC) were measured with homogenates from human brain regions, caduate nucleus and hypothalamus, using our new and highly sensitive methods for l-DOPA decarboxylase and l-5-HTP decarboxylase by high-performance liquid chromatography with electrochemical detection (HPLC-ED). Dopamine formed from l-DOPA as substrate was measured for DOPA decarboxylase activity using d-DOPA for the blank. For 5-HTP decarboxylase activity, serotonin (5-HT) formed from l-5-HTP was measured, and the blank value in presence of NSD-1055 was subtracted. NSD-1055 inhibited 5-HTP decarboxylase activity completely at a concentration of 0.2 mM. In this study, the properties of l-5-HTP decarboxylase activity in human caudate nucleus were first examined. AADC activities in human brains were found to be widely variable for both l-DOPA and l-5-HTP as substrates. The ratio of the activities for l-DOPA and l-5-HTP were found to be significantly higher in hypothalamus than in caudate nucleus. AADC activity for l-DOPA in the brain was found to be linear up to 40 min of incubation, while that for l-5-HTP was found to be linear up to 240 min of incubation. The optimum pyridoxal phosphate concentration was found to be similar for both substrates and was between 0.01 and 0.1 mM. The optimum pH values were found to be 7.2 and 8.2 for l-DOPA decarboxylase and l-5-HTP decarboxylase, respectively. K_m and V_max values for a human caudate nucleus l-DOPA decarboxylase were found to be 414 μM and 482 pmol/min/g wet weight, respectively, while those for l-5-HTP decarboxylase were found to be 90 μM and 71 pmol/min/g wet weight, respectively.     

Studies on 3-epimeric l-2-hexulose phenylosazones. Structure and anomeric configuration of the 3,6-anhydro-osazone derivatives obtained from l-xylo- and l-lyxo-2-hexulose phenylosazone

Dehydration of the 3-epimeric 2-hexulose phenylosazones l-xylo-hexulose phenylosazone and l-lyxo-hexulose phenylosazone afforded 3,6-anhydro-l-lyxo-2-hexulose phenylosazone (2) as the preponderant isomer from both. The identity of 2 was obtained by t.l.c., and by acetylation followed by comparison of the products. Acetylation of 2 with acetic anhydride-pyridine afforded the di-O-acetyl derivative 4, and further acetylation gave the N-acetyldi-O-acetyl derivative 5. Refluxing of 2 with copper sulfate afforded a C-nucleoside analog, namely, 2-phenyl-4-α-l-threofuranosyl-1,2,3-osotriazole (6). The anomeric configuration was determined by n.m.r. spectroscopy. The stereochemical course of the dehydration process and the mass spectra of compounds 2, 4, 5, and 6 are discussed.     

Spirulina ameliorates arsenic induced reproductive toxicity in male rats

Spirulina (Spirulina platensis), has numerous health benefits including antioxidant, immunomodulatory, and anti-inflammatory activities, works against heavy metal toxicity, and is often used as a food supplement in human, animals, birds and fishes. This study aimed to evaluate the protective ability of the dietary spirulina against the toxic effects of inorganic arsenic (iAs) on male reproductive parameters in rats. Seventy-two mature Long-Evans male rats, dividing into six groups (T0, T1, T2, T3, T4 and T5) (12 rats/group) were included in this study. The T3, T4 and T5 group rats were treated with three consecutive doses (1.0 g, 1.5 g and 2.0 g/kg feed) of spirulina in feed along with 3.0 mg NaAsO₂/kg body weight (BW) in drinking water (DW) daily for 90 days. Each rat of group T1 received NaAsO₂ (3.0 mg/kg BW) in DW, and those of T2 group were fed with spirulina (2.0 g/kg feed) daily for 90 days. The rats of group T0 served as the control with normal feed and water. Total arsenic (tAs) contents, reproductive parameters (testicular weight, sperm motility and morphology), and histological changes in the testicles were evaluated in these rats. Arsenic dosing significantly (p=0.003, Kruskal-Wallis test) increased the tAs contents in the testicles, decreased testes weight, sperm morphology and motility compared to the controls. The effect of arsenic dosing was also evidenced by the histological changes like decreased germinal layers in the seminiferous tubules of the treated rats. Moreover, dietary spirulina (2.0 g/kg feed) supplementation significantly (p=0.011, Kruskal-Wallis test) lowered tAs contents in testicles and increases testes weights, sperm motility and morphology. Therefore, spirulina can be used as an effective dietary supplement to ameliorate the adverse effects of arsenic induced reproductive toxicities. However, further study is required to elucidate the underlying molecular mechanisms of reduction of arsenic induced reproductive toxicity by spirulina.     

Infective endocarditis: Role of molecular techniques in early diagnosis

Infective endocarditis (IE), a heart valve infection primarily caused by bacteria such as streptococci or staphylococci, causes significant morbidity and mortality. Despite the long-term use of broad-spectrum antimicrobials, the infection is often difficult to manage. The latest diagnostic modalities for IE are discussed in this study. Blood culture use in pathogen identification can lead to loss of precious time as well as generation of false negative reports. The first steps in diagnosis are blood cultures and echocardiography, but molecular techniques can be extremely useful and may be used for an accurate and early diagnosis.     

Improved Detection of Human Antibodies to a Plasmodium Antigen Using a Peptide Modified with Aib Residues

A 17-mer sequence was selected as a model to study the influence of modifications of terminal ends both on the conformation of a peptide and on its antigenicity towards naturally developing antibodies. This sequence corresponded to a tandemly repeated motif, found in a long repetitive region, with high helical propensity, of a Plasmodium falciparum liver-stage antigen (LSA-1), immunogenic in man. Our model peptide was synthesized with ionizable or non-ionizable ends, or modified in both extremities by introduction of the helix-promoting residue α-aminoisobutyric acid (Aib). Helical contribution, absent in the 17 amino-acid sequence possessing ionizable ends, was detectable when non-ionizable ends were introduced, and dramatically increased in the Aib-modified analogue. The presence of ionizable ends totally abolished reactivity towards human sera, otherwise detectable with the peptide possessing non-ionizable ends. While modification by Aib residues was neither detrimental nor beneficial to antigenicity in solution, it clearly resulted in an improved sensitivity of the specific antibody detection when used as solid-phase antigen in ELISA. © 1997 European Peptide Society and John Wiley & Sons, Ltd.     

Phosphorus Budget for Dal,a Himalayan Lake

The P-budget of Dal Lake in Kashmir is described for a 12 month period. The lake is characterized by high P-loading (7.5 g · m⁻² a⁻¹) and had high P-retention (retention coefficient 0.32). P-loading in the lake showed positive and negative relations with flushing rate and P-retention respectively. A negative relation was similarly found existing between flushing and P-retention. The roles of various biotic and abiotic factors in the P-budget of the lake are described.     

Polycystic ovary syndrome is linked with the fat mass obesity (FTO) gene variants rs17817449 and rs1421085 in western Saudi Arabia

Polycystic ovary syndrome (PCOS) is characterised by infertility, obesity, insulin resistance and clinical and/or biochemical signs of hyperandrogenism. Obesity is known to be correlated with PCOS causing ovulatory dysfunction and hormone imbalances. Moreover, fat mass and the obesity gene (FTO) were linked with obesity and PCOS. Therefore, it is of interest to determine the genotype and allele frequency for three FTO variants - rs17817449 (G/T), rs1421085 (C/T) and rs8050136 (A/C) -in western Saudi population. 95 PCOS patients and 94 controls were recruited for this study. The genetic variants were assayed using real-time polymerase chain reaction using TaqMan genotyping assays. The chi-squared test was applied to investigate the difference between single nucleotide polymorphisms on PCOS and control subjects, and binary logistic regression was used to determine the association of FTO variants with PCOS symptoms. Variants rs17817449 and rs1421085 were significantly linked with PCOS susceptibility in the study population. Rs17817449 and rs8050136 were significantly associated with hair loss in the PCOS group. Furthermore, rs1421085 and rs8050136 were associated with a high body mass index (BMI>30 kg/m2). Risk alleles in our population associated with hair loss and elevated BMI in women with PCOS were homozygous C for rs8050136. This data will help in defining the genetic predisposition of PCOS among women in western Saudi Arabia.