PubMed Health⌕ Search

Biomedical subjects

B K Patel

Publications and source records attributed to B K Patel.

At least 55 records · Page 3Linked to original sources
PubMed1999

Chromatographic resolution, chiroptical characterization and preliminary pharmacological evaluation of the enantiomers of butibufen: a comparison with ibuprofen.

Enantiomeric resolution of butibufen has been achieved on a cellulose tris(3,5-dimethylphenylcarbamate) chiral stationary phase with hexane-isopropanol-trifluoroacetic acid, 100:1.2:0.02 (v/v/v) as mobile phase at a flow rate of 1.0 mL min(-1). Semi-preparative isolation of the enantiomers then chiroptical characterization indicated that the order of elution was (-)-R- before (+)-S-butibufen. When tested for their effects on the cyclooxygenase and 5-lipoxygenase pathways of eicosanoid metabolism in calcium ionophore-activated rat peritoneal leukocytes it was found that (+)-S-butibufen inhibited generation of thromboxane B2 (TXB2) and prostaglandin E2 (PGE2) (cyclooxygenase pathway), with an IC50 of 1.5 microM (approx.), whereas the (-)-R enantiomer was essentially inactive. Neither enantiomer inhibited the 5-lipoxygenase pathway. In this regard, (+)-S-butibufen was approximately five times less potent as a cyclooxygenase inhibitor than (+)-S-ibuprofen. These results show the enantiomeric specificity and pathway selectivity of this novel non-steroidal anti-inflammatory drug.

Animals↗
PubMed1999

Ibuprofen stereochemistry: double-the-trouble?

Racemic ibuprofen is an important NSAID used in the treatment of pain and inflammation in a variety of musculoskeletal and rheumatic disorders. The metabolism of ibuprofen, and that of a number of the related 2-arylpropionic acid NSAIDs, involves chiral inversion of the relatively inactive R-enantiomers to their active S-antipodes, together with other potentially stereoselective conjugative and oxidative pathways. Enantiospecific analytical methodology suitable for the determination of both the drug and its metabolites is essential in order to evaluate the significance of stereoselectivity both in terms of drug action and disposition. Recent investigations have also indicated that the R-enantiomers of these agents may not be totally devoid of useful biological activity, that the formation of acyl-coenzyme A derivatives results in interactions with lipid biochemistry, and has provided new insights into the disposition of these drugs in man. Ibuprofen represents a classical example of a drug where stereochemical considerations are essential for an understanding of its biological properties.

Acyl Coenzyme A↗
PubMed1998

Incorporation of terminal phosphorothioates into oligonucleotides.

Considerable effort has been directed towards studying the structure and function of oligonucleotides and several approaches rely on the attachment of reporter groups to oligonucleotides. We report here the introduction of 3'- and 5'-terminal phosphorothioates into heptameric oligonucleotides and their post-synthetic modification with several reporter groups. The synthesis of terminal phosphorothioates is based on the coupling of a ribonucleoside phosphoramidite at the first or last nucleotide, respectively, which, after sulphurization, is removed by sequential oxidation of the vicinal hydroxyl groups and then beta-elimination. Product formation is of the order of 95%. The ratio of phosphorothioate- versus phosphate-terminated oligodeoxynucleotides as analysed by electrophoresis on a Hg2+gel is in general 85/15. Examples for the reactivity of the terminal phosphorothioates for conjugation with cholesterol, bimane and for sulphydryl exchange are described.

Bridged Bicyclo Compounds↗
PubMed1998

Localization of the human stat6 gene to chromosome 12q13.3-q14.1, a region implicated in multiple solid tumors.

Stat6 signaling pathways have been correlated with functional responses induced by IL-4 and PDGF that may play a role in human malignancy. Utilizing fluorescence in situ hybridization, we mapped the human Stat6 gene to chromosome 12q bands 13.3-14.1, a breakpoint region implicated in a wide variety of solid tumors. To understand the genesis of three human Stat6 variant cDNAs, including a naturally occurring dominant negative species, we further characterized the genomic structure and flanking regions of the human Stat6 gene. The human Stat6 gene encompassed over 19 kb and contained 23 exons. For promoter studies, we introduced flanking sequence 5' of Stat6 exon 1 into a promoterless luciferase reporter vector and characterized basal promoter activity by deletion analysis. DNA sequence analysis revealed potential transcriptional regulation of the putative promoter through numerous consensus binding elements. Finally, we conclude that selective exon deletion and utilization of alternative donor/acceptor sites appear to explain best human Stat6 variant mRNAs.

3T3 Cells↗
PubMed1998

Real-time homogeneous assay of rapid cycle polymerase chain reaction product for identification of Leptonema illini.

Partial 16S rDNA sequences of eight Leptospira-like field isolates that reacted weakly or not at all to microscope agglutination test were found to be similar to the 16S rDNA sequence of the nonpathogen Leptonema illini-type strain 3055. Comparison of these sequences with those of Leptospira 16S rDNA sequences revealed a Leptonema species signature sequence for which a forward amplification primer was designed. This primer was used in conjunction with a bacterial-specific 16S rDNA universal reverse primer for developing a LightCycler-based rapid PCR protocol in which fluorescence emission due to the binding of SYBR green I dye to the amplified products was continuously monitored. A melting temperature (T(m)) determined from the melting curve of the amplified product immediately after PCR confirmed that the product was of Leptonema. The protocol for 24 samples consisting of 30 PCR cycles and melting curve acquisitions required 30 min to complete and agarose gel electrophoresis of the PCR products was not necessary. The method was specific as PCR products were detected from the seven Leptonema reference strains and the eight field isolates that had been previously verified as Leptonema by 16S rDNA sequencing, but not from the two representative strains from each of the eight Leptospira genospecies tested.

Base Sequence↗
PubMed1998

Regulation of interleukin 4-mediated signaling by naturally occurring dominant negative and attenuated forms of human Stat6.

Interleukin (IL)-4-mediated nuclear signaling by Stat6 has been implicated in lymphoid cell proliferation and the transcriptional activation of genes encoding major histocompatability complex (MHC) class II molecules and Fc receptors. To investigate IL-4-mediated transcriptional events, we cloned two naturally occurring human Stat6 isoforms, Stat6b and Stat6c, that encoded an NH2-terminal truncation or an SH2 domain deletion, respectively. Stat6 variant mRNAs were differentially expressed in many human tissues. To elucidate the biologic role of each isoform, we examined the consequences of overexpression in IL-4-responsive FDC-P2 cells. Stat6 and Stat6b (to a lesser extent) enhanced DNA synthesis, up-regulated endogenous MHC class II and Fcgamma receptors, and became tyrosine phosphorylated in response to IL-4 stimulation. In contrast, Stat6c, which lacks functionally critical SH2 domain residues, unexpectedly inhibited IL-4-mediated mitogenesis and cell surface antigen expression and was not tyrosine phosphorylated. Although Stat6c only modestly diminished endogenous Stat6 tyrosine phosphorylation, it abolished endogenous Stat6 FcgammaRI and Iepsilon DNA binding activity and FcgammaRI-luciferase reporter transcriptional activation. Our results indicate that the molecular mechanism of inhibition by Stat6c was due to suppression of endogenous Stat6 dimer formation. Thus, Stat6b and Stat6c are naturally occurring attenuated and dominant negative Stat6 variants, respectively, that affect IL-4-mediated biologic responses through differential transcriptional regulation.

Amino Acid Sequence↗
PubMed1998

Urethral complications of urinary catheterization presenting as primary scrotal masses: sonographic diagnosis.

We report on 2 debilitated male patients who had penile urethral complications of transurethral catheter drainage. One patient had a urethral diverticulum, and the other had a Foley catheter misplaced through a urethral perforation. Both lesions mimicked primary intrascrotal masses on physical examination and were therefore evaluated by scrotal sonography. The correct diagnosis of each lesion required careful examination of the mass and its anatomic relationship to the adjacent urethra. Penile urethral complications of catheterization in debilitated patients must be included in the differential diagnosis of scrotal cystic masses. These cases also emphasize the necessity of a thorough sonographic examination that extends beyond the specific area of presumed clinical interest.

Diverticulum↗
PubMed1998

FgoI, a Type II restriction endonuclease from the thermoanaerobe Fervidobacterium gondwanense AB39(T).

Restriction endonuclease activity was detected in 11 out of 13 Fervidobacterium isolates, including F. islandicum H21(T), F. gondwanense AB39(T), and nine other Fervidobacterium-like strains isolated from the Great Artesian Basin of Australia. The restriction endonuclease from F. gondwanense AB39(T) was partially purified and designated FgoI. FgoI recognized a 4 nucleotide sequence 5'-CTAG-3' and cleaved between nucleotides C and T to produce a 2 base 5' overhang (5'-C/TAG-3'). As predicted from the enzyme recognition and cleavage specificity, FgoI was found to cleave delta DNA 13 times, phiX174 three times, pBR322 five times, pUC18 four times, and pSK six times. FgoI exhibited a broad temperature optimum range (between 60 to 70 degrees C) and was active at pH 6.5 to 8.5, but not at pH 9.0. Manganese could replace magnesium as a cofactor for activity, but not cobalt chloride, calcium chloride, cupric chloride, or zinc chloride. The restriction endonuclease was completely inactivated by phenol/chloroform extraction and was heat inactivated at 80 degrees C for 60 min or at 100 degrees C for 15 min. FgoI has been identified as a heat stable isoschizomer of the Type II restriction endonucleases, MaeI and BfaI.

Journal Article↗
PubMed1998

Aminobacterium colombiensegen. nov. sp. nov., an amino acid-degrading anaerobe isolated from anaerobic sludge.

A new gram-negative, non-sporulating, mesophilic, amino acid fermenting bacterium, designated strain ALA-1(T) (T = type strain), was isolated from an anaerobic lagoon of a dairy wastewater treatment plant. The strain is curved (3-4 microm x 0.2-0.3 microm) and occurs singly or in pairs. Optimum growth occurs at 37 degrees C and pH 7.3. The G+C content of the DNA is 46 mol %. The strain requires yeast extract for growth, grows poorly on casamino acids, peptones, cysteine, and alpha-ketoglutarate, but readily grows on serine, threonine, glycine and pyruvate. When cocultured with the hydrogenotrophic methanogen Methanobacterium formicicum, strain ALA-1(T) oxidized alanine, glutamate, leucine, isoleucine, valine, aspartate, and methionine. Phylogenetic analysis revealed that it forms a distinct and independent line of descent in the vicinity of Dethiosulfovibrio peptidovorans, Dictyoglomus thermophilum, and Anaerobaculum thermoterrenum which are members of the low G+C containing gram-positive bacteria. The phylogenetic results concur with the phenotypic and genomic data which reveal that it is a novel strain. Based on these findings, we designate strain ALA-1(T) as Aminobacterium colombiense (DSM 12261) gen. nov., sp. nov.

Journal Article↗
PubMed1998

Eubacterium aggreganssp. nov., a new homoacetogenic bacterium from olive mill wastewater treatment digestor.

A strictly anaerobic, homoacetogenic, gram-positive, non spore-forming bacterium, designated strain SR12(T) (T = type strain), was isolated from an anaerobic methanogenic digestor fed with olive mill wastewater. Yeast extract was required for growth but could also be used as sole carbon and energy source. Strain SR12(T) utilized a few carbohydrates (glucose, fructose and sucrose), organic compounds (lactate, crotonate, formate and betaine), alcohols (methanol), the methoxyl group of some methoxylated aromatic compounds, and H2 + CO2. The end-products of carbohydrate fermentation were acetate, formate, butyrate, H2 and CO2. End-products from lactate and methoxylated aromatic compounds were acetate and butyrate. Strain SR12(T) was non-motile, formed aggregates, had a G+C content of 55 mol % and grew optimally at 35 degrees C and pH 7.2 on a medium containing glucose. Phylogenetically, strain SR12(T) was related to Eubacterium barkeri, E. callanderi, and E. limosum with E. barkeri as the closest relative (similarity of 98%) with which it bears little phenotypic similarity or DNA homology (60%). On the basis of its phenotypic, genotypic, and phylogenetic characteristics, we propose to designate strain SR12(T) as Eubacterium aggregans sp. nov. The type strain is SR12(T) (= DSM 12183).

Journal Article↗
PubMed1998

Increase in plasma leptin and Lep mRNA concentrations by food intake is dependent on insulin.

Obese (Lep) gene expression and leptin secretion are regulated by changes in food intake. However, the mechanism by which leptin concentrations are altered by fasting and feeding is unclear. Since these changes occur in parallel with changes in plasma insulin, it is possible that the changes observed are mediated by insulin. To test this hypothesis, we studied the role of insulin in the regulation of Lep gene expression in epididymal fat and leptin secretion during feeding. As shown previously, fasted animals showed significant reductions in Lep mRNA, plasma leptin, and plasma insulin concentrations. Conversely, feeding increased plasma insulin, Lep mRNA, and plasma leptin. In streptozotocin (STZ)-treated animals, plasma insulin concentrations were low. This was associated with low Lep mRNA and plasma leptin concentrations. Changes in food intake, whether fasting or feeding, did not significantly alter plasma insulin levels in STZ-treated animals. Under these circumstances, Lep mRNA and plasma leptin concentrations also remained low. Our results demonstrate that the decrease in Lep mRNA and plasma leptin during fasting and the increase with feeding are dependent on changes in the plasma insulin concentration.

Animal Feed↗
PubMed1998

Identification of Leptospira inadai by continuous monitoring of fluorescence during rapid cycle PCR.

Seven new Leptospira isolates from rats, a buffalo, and contaminated media showed either reactive serology against more than 1 serogroup or no reactive serology against a reference panel of 22 serovars in the microscopic agglutination test (MAT). Because of these inconclusive results, the 16S rDNA sequences of these isolates were determined and found to resemble that of the type strain of Leptospira inadai (L. inadai), serovar lyme strain 10, which is considered to be nonpathogenic for humans. Comparative analyses of other Leptospira 16S rDNA sequences from databases revealed a L. inadai-specific signature sequence, against which an amplification primer was designed. This primer when used in conjunction with an universal primer enabled the trial of a rapid PCR protocol in which fluorescence emissions due to binding of SYBR Green I dye to PCR products were continuously monitored during rapid thermal cycling. A melting curve acquired immediately after PCR was used to distinguish the intended product. The thermal cycling and continuous monitoring of fluorescence emission were accomplished by the LightCycler; the whole procedure of 30 PCR cycles and melting curve acquisition required only 20 minutes. The primer achieved the required specificity, as the intended PCR product resulted only from 6 confirmed L. inadai reference strains and 7 field isolates that had been verified as L. inadai by the 16S rDNA sequencing, but not from 16 reference strains of Leptospira belonging to 7 other genospecies. Furthermore, these experiments showed that the PCR protocol was robust because target DNA of different conditions, which were extracted by either 1 of the 4 methods used, could be detected.

Animals↗
PubMed1998

Desulfovibrio aminophilus sp. nov., a novel amino acid degrading and sulfate reducing bacterium from an anaerobic dairy wastewater lagoon.

A mesophilic strain of sulfate-reducing bacterium, designated ALA-3T (T = type strain), was isolated from an anaerobic lagoon of a dairy wastewater treatment plant. The curved, Gram-negative, non-sporeforming cells (0.2 x 3.0-4.0 microns) existed singly or in chains, and were motile by single polar flagella. Optimum growth occurred at 35 degrees C and pH 7.5 on a medium containing lactate and sulfate. Thiosulfate or sulfite but not elemental sulfur, nitrate, or fumarate could also replace sulfate as an electron acceptor. Formate, alanine, aspartate, leucine, isoleucine, valine, and methionine, H2/CO2 and ethanol also served as electron donors with sulfate as an electron acceptor. Pyruvate, casamino acids, peptone, serine, glycine, cysteine and threonine were fermented. Sulfite and thiosulfate were disproportionated to sulfate and sulfide. The G + C content of the DNA was 66 mol % G + C. Phylogenetic analysis revealed that Desulfovibrio africanus was the nearest relative (similarity of 89%). Strain ALA-3T is physiologically and phylogenetically different from other Desulfovibrio species, and is designated Desulfovibrio aminophilus sp. nov. (DSM 12254).

Amino Acids↗
PubMed1998

Caldicellulosiruptor owensensis sp. nov., an anaerobic, extremely thermophilic, xylanolytic bacterium.

An anaerobic, extremely thermophilic, xylanolytic, non-spore-forming bacterium was isolated from a sediment sample taken from Owens Lake, California, and designated strain OLT (T = type strain). Strain OLT had a Gramnegative reaction and occurred as short rods which sometimes formed long chains containing a few coccoid cells. It grew at 50-80 degrees C, with an optimum at 75 degrees C. The pH range for growth was 5.5-9.0 with an optimum at about pH 7.5. When grown on glucose at optimal conditions, its doubling time was 7.3 h. In addition to glucose, the isolate utilized sucrose, xylose, fructose, ribose, xylan, starch, pectin and cellulose. Yeast extract stimulated growth on carbohydrates but was not obligately required. The end products from glucose fermentation were lactate, acetate, ethanol, H2 and CO2. The G + C content of strain OLT was 36.6 mol%. The 16S rDNA sequence analysis indicated that strain OLT was a member of the subdivision containing Gram-positive bacteria with DNA G + C content of less than 55 mol% and clustered with members of the genus Caldicellulosiruptor. Because strain OLT is phylogenetically and phenotypically different from other members of this genus, it is proposed to designate this isolate Caldicellulosiruptor owensensis sp. nov. Strain OLT is the type strain (= ATCC 700167T).

Bacteria, Anaerobic↗
PubMed1998

Desulfotomaculum halophilum sp. nov., a halophilic sulfate-reducing bacterium isolated from oil production facilities.

A halophilic endospore-forming, sulfate-reducing bacterium was isolated from an oilfield brine in France. The strain, designated SEBR 3139, was composed of long, straight to curved rods. It grew in 1-14% NaCl with an optimum at 6%. On the basis of morphological, physiological and phylogenetical characteristics, strain SEBR 3139 should be classified in the genus Desulfotomaculum. However, it is sufficiently different from the hitherto described Desulfotomaculum species to be considered as a new species. Strain SEBR 3139T (= DSM 11559T) represents the first moderate halophilic species of the genus Desulfotomaculum. The name Desulfotomaculum halophilum sp. nov. is proposed.

Base Sequence↗
PubMed1998

Methanocalculus halotolerans gen. nov., sp. nov., isolated from an oil-producing well.

Two irregular coccoid methanogens designated SEBR 4845T and FR1T were isolated from an oilfield in Alsace, France. Strain SEBR 4845T (T = type strain) is a hydrogenotrophic halotolerant methanogen, which grows optimally at 5% NaCI (w/v) and tolerates up to 12% NaCI. It does not use methylated compounds and therefore cannot be ascribed to any of the known genera of the halophilic methylotrophic methanogens. It differs from hydrogenotrophic members of the orders Methanococcales and Methanomicrobia les in the NaCI growth range (0-12% NaCI), which is the widest reported to data for any hydrogenotrophic methanogen. 16S rRNA gene sequence analysis indicated that strain SEBR 4845T is a novel isolate for which a new genus is proposed, Methanocalculus halotolerans gen. nov., sp. nov. (= OCM470T) that might be indigenous to the oilfield ecosystem. Strain FR1T (=OCM 471) is a moderately halophilic methanogen which growths optimally at 10% NaCI and tolerates up to 20% NaCI. It grows on trimethylamine and methanol as carbon and energy sources. The G+C content of its DNA is 43 mol%. It is therefore phenotypically and genotypically related to members of the genus Methanohalophilus. This report provides evidence that methylotrophic and hydrogenotrophic, but not aceticlastic methanogens are present in a saline subsurface oilfield environment, as already observed in surface saline to hypersaline environments.

Base Sequence↗
PubMed1998

Ammonia-hyperproducing bacteria from New Zealand ruminants.

Pasture-grazed dairy cows, deer, and sheep were tested for the presence of ammonia-hyperproducing (HAP) bacteria in roll tubes containing a medium in which tryptone and Casamino Acids were the sole nitrogen and energy sources. Colonies able to grow on this medium represented 5.2, 1.3, and 11.6% of the total bacterial counts of dairy cows, deer, and sheep, respectively. A total of 14 morphologically distinct colonies were purified and studied further. Restriction fragment length polymorphisms of 16S rRNA genes indicated that all isolates differed from the previously described HAP bacteria, Clostridium aminophilum, Clostridium sticklandii, and Peptostreptococcus anaerobius. Carbon source utilization experiments showed that five isolates (C2, D1, D4, D5, and S1) were unable to use any, or very few, of the carbon sources tested. Biochemical tests and phylogenetic analyses of 16S ribosomal DNA sequences indicated that all isolates were monensin sensitive; that D1 and S1 belonged to the genus Peptostreptococcus, that D4 and D5 belonged to the family Bacteroidaceae, where D4 was similar to Fusobacterium necrophorum; and that C2 was most similar to an unidentified species from the genus Eubacterium. Growth on liquid medium containing tryptone and Casamino Acids as the sole nitrogen and energy source showed that D1, D4, and S1 grew rapidly (specific growth rates of 0.40, 0.35, and 0.29 h-1, respectively), while C2 and D5 were slow growers (0.25 and 0.10 h-1, respectively). Ammonia production rates were highest in D1 and D4, which produced 945.5 and 748.3 nmol/min per mg of protein, respectively. Tests of individual nitrogen sources indicated that D1 and D4 grew best on tryptone, S1 grew equally well on Casamino Acids or tryptone, and C2 and D5 grew poorly on all nitrogen sources. The intact proteins casein and gelatin did not support significant growth of any of the isolates. These isolates extend the diversity of known HAP rumen bacteria and indicate the presence of significant HAP bacterial populations in pasture-grazed New Zealand ruminants.

Ammonia↗