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Biomedical subjects

B A White

Publications and source records attributed to B A White.

At least 55 records · Page 3Linked to original sources
PubMed1997

Effects of the protein tyrosine kinase inhibitor, herbimycin A, on prolactin gene expression in GH3 and 235-1 pituitary tumor cells.

The high basal level of prolactin (PRL) gene expression in rat pituitary GH3 cells is maintained through the spontaneous activity of voltage-sensitive calcium channels (VSCCs). This can be observed experimentally by addition of 0.5 mM CaCl2 to GH3 cells cultured in a low calcium, serum-free medium. CaCl2 specifically induces PRL gene expression and this induction is inhibited by VSCC blockers. PRL gene expression is also stimulated by several hormones and growth factors. In the present study, we examined the effects of tyrosine kinase inhibitors on the ability of CaCl2, basic fibroblast growth factor (bFGF), epidermal growth factor (EGF) and thryrotropin-releasing hormone (TRH) to increase PRL mRNA levels. Of several PTK inhibitors used, one PTK inhibitor, herbimycin A, specifically inhibited the CaCl2-induced increase in cytoplasmic and nuclear prolactin (PRL) mRNA without affecting cell viability, cell-cell and cell-matrix adhesion, or the expression of several other genes. The effects of herbimycin A were reversible. In cells pretreated with herbimycin A, PRL mRNA levels were reduced by 69 +/- 12% (P < 0.001; n = 4). Western blot analysis using anti-phosphotyrosine antibody revealed a decrease of 91 +/- 1% (P < 0.001; n = 4) in the phosphotyrosine content of proteins in the molecular weight range of 130-160 kDa. After changing the medium back to SFM plus 0.5 mM CaCl2, levels of PRL mRNA increased over a period of several hours, and this increase was accompanied by the tyrosine phosphorylation of two or more proteins in the approximate size range of 130-160 kDa. Herbimycin A also inhibited PRL gene expression in the independently-derived 235-1 lactotrope cell line and lowered the tyrosine specific phosphorylation of protein(s) in a similar size range. Herbimycin A inhibited the ability of bFGF, EGF and TRH to stimulate PRL gene expression in GH3 cells. Again, in cells pretreated with herbimycin A, bFGF induced a reappearance of tyrosine-specific phosphorylation, followed by a reappearance of PRL mRNA. These findings provide evidence for a role for at least one PTK which is necessary for basal and stimulated PRL gene expression.

Animals↗
PubMed1997

Ribotyping of adherent Lactobacillus from weaning pigs: a basis for probiotic selection based on diet and gut compartment.

Dietary inoculates for weaned pigs often include lacobacilli, but the effects of age and diet on the ecology of adherent lactobacilli are not well known. Four experimental treatments included 16 newborn piglets: a pre-weaning treatment (PW) included four pigs that were sacrificed at 28 days of age; a sow treatment (Sow) had four pigs that remained with the sow (Sow) from 28 to 38 days of age and were sacrificed at 38 days of age; and two treatments in which four pigs each, were placed on a corn-soy diet with (CSL), or without (CS) 40% lactose. Adherent lactobacilli were isolated from the pars esophagus, ileum, and cecum, and characterised phenotypically. A 23S rDNA probe hydrized toEcoRI orPstI digested DNA, and a 74.8% cut-off individualize isolates into 36 clusters. The most predominant strains found in the Sow, CSL, and CS treatments were the same, but different strains predominated in the PW animals. The most predominant strains found in the pars esophagus and ileum were the same, but different strains predominated in the cecum.

Journal Article↗
PubMed1996

Complete nucleotide sequence of a cryptic plasmid, pBAW301, from the ruminal anaerobe Ruminococcus flavefaciens R13e2.

The complete nucleotide sequence of a cryptic plasmid designated pBAW301, from the Gram-positive ruminal bacterium Ruminococcus flavefaciens R13e2, has been determined. This plasmid is 1768 bp in size and has an overall G+C content of 43.5%. Computer analysis of the sequence data revealed an open reading frame, ORF1 (256 amino acids), which is similar to the Rep protein of the Bacillus borstelensis plasmid pHT926. ORF1 is preceded by Shine-Dalgarno and Escherichia coli-10 and -35 like sequences. Nine smaller open reading frames showed no significant homologies to known protein sequences. Analysis of replication intermediates and the nucleotide sequence indicate that the plasmid does not replicate by a rolling-circle mode of replication similar to other plasmids from Gram-positive bacteria. Moreover, sequences typical of theta replication origins were not found in the nucleotide sequence of pBAW301. These data suggest that this plasmid either replicates by an as yet undescribed mechanism, or represents a new class of theta replicating plasmids.

Amino Acid Sequence↗
PubMed1996

Tumor necrosis factor beta gene polymorphism and early primary kidney allograft loss.

The purpose of this study was to examine the association of TNFB alleles and genotypes in recipients experiencing early cadaveric kidney graft loss and non-early graft loss. Because the TNFB1 allele is associated with increased production of the TNF beta lymphotoxin following PHA mitogenic stimulation in vitro, the frequency of this allele was examined in renal transplant recipients experiencing early graft loss. A similar expression of TNFB alleles and genotypes was found in the early regraft loss group (< or = 3 months; n = 16) and non-early graft loss group (n = 81). We conclude that alleles of the TNFB gene are not risk factors for early cadaveric kidney graft loss.

Female↗
PubMed1996

Steroidogenic factor-1 expression is transiently repressed and c-myc expression and deoxyribonucleic acid synthesis are induced in rat granulosa cells during the periovulatory period.

The expression of steroidogenic factor 1 (SF-1), cytochrome P450 aromatase (P450arom), and cytochrome P450 cholesterol side-chain cleavage (P450scc) was examined during the periovulatory period. Immature rats were injected with eCG to induce development of ovarian follicles to the preovulatory stage. At 48 h after the eCG injection, the LH surge was simulated by an injection of an ovulatory dose of hCG, and RNA was isolated at 0, 2, 4, 6, 8, and 24 h after hCG injection. The mRNA levels for SF-1, P450arom, and P450scc were relatively high in total ovarian RNA samples from eCG-treated rats. Levels of SF-1 and P450arom mRNA decreased within 2 h after injection of hCG. The SF-1 mRNA levels gradually increased from 4 to 24 h. Aromatase levels remained undetectable until 24 h after hCG. P450scc mRNA levels increased throughout the 24-h period after hCG. Levels of SF-1 and P450arom, but not P450scc, mRNA were also reduced in RNA samples from isolated granulosa cells at 4 h after hCG treatment relative to those from eCG-treated rats. In situ hybridization analysis also revealed that hCG uniformly suppressed SF-1 mRNA levels an all granulosa cells compared to those of eCG-treated controls. The relationship of SF-1 expression to immediate/early gene expression and cell cycle traverse was also examined. C-myc mRNA levels were induced by up to 10-fold at 4 h after hCG injection. Similarly, DNA synthesis, as measured by the percentage of granulosa cells that incorporated 5'-bromodeoxyuridine, was increased from 16 +/- 4% in eCG-treated rats to 61 +/- 7% at 4 h after hCG treatment (p < 0.05). This study provides the novel finding that SF-1 expression is transiently repressed to very low levels in response to the LH surge. Further, these studies suggest that granulosa cells traverse the cell cycle before becoming terminally differentiated luteal cells.

Animals↗
PubMed1996

An endo-beta-1,4-glucanase gene (celA) from the rumen anaerobe Ruminococcus albus 8: cloning, sequencing, and transcriptional analysis.

A genomic library of Ruminococcus albus 8 DNA was constructed in Escherichia coli using bacteriophage lambda ZapII. This library was screened for cellulase components and several Ostazin brilliant red/carboxymethyl cellulose positive clones were isolated. All of these clones contained a common 3.4-kb insert, which was recovered as a plasmid by helper phage excision. The carboxymethyl cellulase coding region was localized to a 1.4-kb region of DNA by nested deletions, and a clone containing the entire celA gene was sequenced. Analysis of the sequence revealed a 1231-bp open reading frame, coding for a protein of 411 amino acids with a predicted molecular weight of 45 747. This protein, designated CelA, showed extensive homology with family 5 endoglucanases by both primary amino acid sequence alignment and hydrophobic cluster analysis. Cell-free extracts of E. coli containing the celA clone demonstrated activity against carboxymethyl cellulose and acid swollen cellulose but not against any of the p-nitrophenol glycosides tested, indicating an endo-beta-1,4-glucanase type of activity. In vitro transcription-translation experiments showed that three proteins of 48,000, 44,000, and 23,000 molecular weight were produced by clones containing the celA gene. Northern analysis of RNA extracted from R. albus 8 grown on cellulose indicated a celA transcript of approximately 2700 bases, whereas when R. albus 8 was grown on cellobiose, celA transcripts of approximately 3000 and 600 bases were detected. Primer extension analysis of these RNAs revealed different transcription initiation sites for the celA gene when cells were grown with cellulose or cellobiose as the carbon source. These two sites differed by 370 bases in distance. A model, based on transcription and sequence data, is proposed for celA regulation.

Amino Acid Sequence↗
PubMed1996

Selected restoration and tooth conditions: United States, 1988-1991.

The DMF index provides one source of information on past and present dental caries experience; however, important limitations hinder its ability to characterize fully the impact of dental caries. The purpose of this paper is to describe a measure of selected restoration and tooth conditions that supplements information from the DMF index and to report on the application of this measure as part of the Third National Health and Nutrition Examination Survey, Phase 1, conducted between 1988 and 1991. Data from this survey were used to estimate the prevalence and severity of selected disaggregated physical and biological oral conditions among dentate adults aged 18 to 74 years. Trained, standardized, and calibrated dentist examiners assessed 28 permanent teeth or tooth spaces for each of 6,767 subjects. Teeth or tooth spaces were classified based on criteria for: defective intracoronal restorations, crowns, or bridges; gross loss of tooth structure associated with a restoration; pulpal involvement; or retained roots. Approximately 40.5%, or 61.6 million, dentate adults had at least one tooth or tooth space that met the criteria. Among all persons, an average of 0.9 teeth or tooth spaces met the criteria for at least one category. Adults with at least one scored tooth or tooth space had an average of 2.2 such teeth or tooth spaces. Data from this assessment supplement information available from the DMF index to provide a broader profile of the impact of dental caries on permanent teeth of US adults.

Adolescent↗
PubMed1996

Steroidogenic factor-1 as a positive regulator of rat granulosa cell differentiation and a negative regulator of mitosis.

Ovarian follicles contain small nonaromatase-expressing and large aromatase-expressing granulosa cells (GCs). The present studies were designed to determine whether small GCs can differentiate into large GCs and/or express aromatase. Additional studies were conducted to assess the role of steroidogenic factor-1 (SF-1), an orphan nuclear receptor, in regulating GC differentiation and proliferation. For these studies, small GCs were isolated from immature rats by Percoll gradient centrifugation and cultured for up to 48 h with FSH and/or 8-bromo-cAMP (8-br-cAMP). FSH/8-br-cAMP induced a 2-fold increase in SF-1 messenger RNA levels within 4 h. This increase was maintained throughout the culture period. By 24 h culture, FSH/8-br-cAMP increased the percentage of large GCs. It was not until 48 h of culture with FSH and 8-br-cAMP that aromatase expression increased. This increase was detected by both Western blot and quantitative immunocytochemistry. 8-br-cAMP alone did not promote GC differentiation. Small GCs were then cultured with FSH/8-br-cAMP in the presence or absence of an antisense oligonucleotide complementary to the putative SF-1 ligand-binding site (SF-1 AS). As a control, small GCs were cultured with FSH/8-br-cAMP and an 18-mer nonsense oligonucleotide (SF-1 NS). The SF-1 AS, but not the SF-1 NS, prevented FSH/8-br-cAMP from increasing 1) SF-1 messenger RNA levels, 2) transcription of a SF-1(x2) promoter/luciferase construct, 3) GC size, and 4) aromatase expression. In a third series of experiments, small GCs were cultured for 24 h in 1) control media supplemented with 2) a mitogen, phorbol ester [12-O-tetraphorbol acetate (TPA)], 3) FSH/8-br-cAMP, or 4) both. TPA increased the number of GCs by 51 +/- 9%. FSH/8-br-cAMP completely blocked TPA-induced mitosis. When small GCs were cultured with FSH/cAMP, TPA, and SF-1 AS, the number of GCs increased by 50 +/- 7%. This increase was not observed with SF-1 NS. Taken together, these data demonstrate that SF-1 is expressed in both small and large GCs, and enhanced SF-1 expression is part of the molecular mechanism associated with GC differentiation. Interestingly, SF-1 not only regulates differentiation, but also inhibits TPA-induced GC mitosis.

Animals↗
PubMed1996

Dental caries, restoration and tooth conditions in U.S. adults, 1988-1991. Selected findings from the Third National Health and Nutrition Examination Survey.

This article provides estimates of dental caries experience and selected restorative and tooth conditions among U.S. adults, obtained from Phase 1 (1988-1991) of the Third National Health and Nutrition Examination Survey. Between 1988 and 1991, 94 percent of adults in the United States showed evidence of past or present coronal caries. Based on the data collected, the authors estimate that about 40.5 percent, or 61.6 million, dentate adults had at least one tooth or tooth space that could potentially benefit from professional treatment. Minimally, it is estimated that 135.6 million tooth or tooth spaces among U.S. adults may benefit from professional treatment. These estimates supplement information available from the DMF index to provide a broader profile of the impact of dental caries on permanent tooth of U.S. adults.

Adolescent↗
PubMed1996

A health plan report card for dentistry.

Employers are demanding information about the performance of the health care plans they purchase for their employees. As a result, "report cards" are now beginning to appear that provide standardized, population-based comparison data for managed medical care plans' quality of care, access and member satisfaction, utilization, and financial status. Although report cards for dental care plans have not yet been developed, it is likely that purchasers will soon expect such performance information. A prototype report card for dental managed care plans is proposed in an effort to facilitate the development of a consensus standard for dentistry. The thirty-eight measures proposed for the report card are designed to be obtainable with a realistic level of additional effort in most dental practices. They were selected to provide data on questions of importance to purchasers and to assess processes and outcomes important because there is strong evidence for their effectiveness. The rationale for the measures is discussed, as are the steps required to develop more sophisticated measures. While the responsibility for the procurement of the information needed for dental report cards will die initially with administrators of dental care plans, it is likely in the near future that individual practitioners will be expected to supply this information to both individual patients and potential contractors.

Administrative Personnel↗
PubMed1995

Cellular and molecular mechanisms that mediate insulin-dependent rat granulosa cell mitosis.

Rat ovarian follicles are composed of small and large granulosa cells (GC). The present studies demonstrate that small GCs undergo insulin- or phorbol ester-dependent mitosis in vitro. In order to examine the cellular and molecular events that account for insulin's mitogenic action, small GCs were cultured with either insulin, phorbol ester (TPA), or both insulin and TPA. Insulin and TPA increased GC numbers by 21 +/- 3% and 20 +/- 2% over control values, respectively (p < 0.05). Simultaneous addition of insulin and TPA increased GC numbers by 20 +/- 3% (p < 0.05). In a second experiment, small GCs were exposed to control medium, insulin, staurosporine (a protein kinase C [PKC] inhibitor), or both insulin and staurosporine. These studies revealed that insulin induced a 21 +/- 5% increase in GC numbers and that staurosporine blocked insulin's mitogenic action. These observations suggest that insulin mediates its mitogenic action through a PKC-dependent mechanism. Since the proto-oncogenes, c-fos and c-jun, are expressed during GC mitosis, studies were undertaken to determine whether or not the expression of these two proto-oncogenes products was enhanced by insulin. The expression of c-fos and c-jun proteins was assessed by immunocytochemistry. These studies showed that after 5 h, insulin increased the percentage of cells that stained for c-fos and c-jun by 15 +/- 2% and 19 +/- 4, respectively (p < 0.05). The expression of these proto-oncogenes was blocked by staurosporine. Both progesterone and 8-br-cAMP, which block insulin-dependent GC mitosis, also inhibited the expression of c-fos and c-jun.(ABSTRACT TRUNCATED AT 250 WORDS)

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1995

Nucleotide sequence and transcriptional analysis of the celD beta-glucanase gene from Ruminococcus flavefaciens FD-1.

The nucleotide sequence of the celD gene, which encodes endoglucanase and xylanase activity, from Ruminococcus flavefaciens FD-1 was determined. The DNA sequence of celD contains an open reading frame of 1215 nucleotides that encodes a polypeptide of 405 amino acids with a molecular mass of 44,631 Da. The primary amino acid sequence of CelD was screened against the GenBank data base for similar polypeptide sequences and the analysis indicated that CelD has common features with endoglucanases from the family E cellulases. Both hydrophobic cluster and BESTFIT (Genetics Computer Group (University of Wisconsin) package) analyses confirmed this relationship. Pairwise alignments using BESTFIT revealed that CelD was most closely related to endE4 from Thermomonospora fusca over a 160 amino acid window. The histidine, aspartate, and glutamate residues identified as being essential for catalytic activity in family E cellulases are conserved in CelD. A Shine-Dalgarno-like sequence was present 5 base pairs (bp) upstream of the translation start site. Primer extension analysis indicated that different transcription initiation sites are used to initiate transcription of celD in Escherichia coli and R. flavefaciens. In the case of R. flavefaciens the transcription initiation site is at a T residue (nucleotide 273) 16 bp upstream from the translational start site. A region resembling a sigma 70-like-10 promoter sequence is present upstream from the transcription initiation site but there is no apparent-35 region. In contrast, transcription in E. coli is initiated at a C residue 258 bp upstream from the translational start site and a sequence resembling a omega 70-like-10 region is present 5 bp upstream of this residue.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1995

DNA sequence and transcriptional characterization of a beta-glucanase gene (celB) from Ruminococcus flavefaciens FD-1.

The recombinant clone pBAW101 (in pBluescript SK-) contains the celB endoglucanase gene from Ruminococcus flavefaciens FD-1. Subcloning indicated that the endoglucanase activity expressed was present within a 2.4-kb insert (pBAW104). The nucleotide sequence of the celB gene was determined, and upon analysis, revealed an open reading frame of 1943 nucleotides that encodes a polypeptide of 632 amino acids with a molecular weight of 69,414. A putative Shine-Dalgarno sequence was identified 6 bp upstream from the translation start site. The N-terminal 32 amino acid residues were typical of prokaryotic signal sequences. Hydrophobic cluster analysis (HCA) and DNA alignment of CelB to other published beta-glucanase polypeptide sequences in GenBank indicate that CelB belongs in HCA cellulase family 44. Primer extension analyses were performed using RNA isolated from R. flavefaciens grown on cellulose and cellobiose, and from Escherichia coli containing the plasmid clone pBAW104. Transcription is initiated at different sites in E. coli and R. flavefaciens. In the case of R. flavefaciens transcription is initiated at a C residue (nucleotides 329), 221 bp upstream from the translation start site. There were no regions resembling E. coli sigma 70-like promoter sequences present upstream from this putative transcription initiation site. In contrast, numerous transcription initiation sites were identified when RNA from E. coli was used in the primer extension analyses.

Amino Acid Sequence↗
PubMed1995

Effect of weaning diet on the ecology of adherent lactobacilli in the gastrointestinal tract of the pig.

Sixteen pigs were included in an investigation of the effects of weaning and weaning diet on the ecology of adherent Lactobacillus species in the gastrointestinal tract. At 28 d of age four pigs were killed and were designated as the preweaning control (PW). Four pigs remained on the sow (Sow), four pigs were fed a corn-soy-lactose (CSL) diet, and the remaining four pigs were fed a corn-soy (CS) diet. Pigs from the latter three treatments were killed at 38 d of age. Tissue samples were taken from the pars esophagus, ileum, and cecum and the adherent lactobacilli were enumerated using Rogosa SL agar. Bacterial colonies were randomly selected from Rogosa SL agar plates and speciated using cell type, morphology, and substrate fermentation tests. The species data were used to calculate the Shannon, Simpson, and evenness diversity indices. Shannon and Simpson diversity index values when averaged across tissues were lower (P < .05) for PW than for postweaning treatments (Sow, CSL, and CS) and lower (P < .05) when pigs receiving sow's milk (PW and Sow) were compared with pigs receiving the dry diets (CSL and CS). The diversity of adherent Lactobacillus is altered by the form of the diet fed to weanling pigs, and statistical ecological methods provide a powerful way of analyzing the ecology of the gastrointestinal tract.

Animals↗
PubMed1995

A quarter century of changes in oral health in the United States.

This paper provides an overview of the oral health status of Americans since the 1960s. Data from seven national surveys, conducted between 1960 and 1987, have been presented. Estimates of coronal and root caries, periodontal diseases, and tooth loss were reviewed. In addition, data on edentulism and oral cavity and pharyngeal cancer were included. Although the purpose of this paper is descriptive rather than analytical, some important trends have been noted: The number of children who were free from dental caries increased dramatically between 1963 and 1987. By 1987, almost one-half of school children between the ages of 5 and 17 were caries-free. Among those children with dental decay, the number of teeth affected has also declined. The oral health of adults also improved during the 27-year period included in this review. In particular, the mean number of missing teeth and the percentage of edentulous adults have declined substantially. Trends in periodontal diseases were difficult to determine due to changes in the measures of periodontal diseases utilized in the surveys. In the most recent survey of employed U.S. adults, approximately 44 percent were found to have gingivitis and slightly more than 13 percent had periodontal pockets 4-5 mm in depth. Approximately 30,000 new cases of oral cavity and pharyngeal cancer were diagnosed in 1993, resulting in approximately 8,000 deaths. African Americans have higher incidence and mortality rates than white Americans and also have a much lower five-year survival rate.

Adolescent↗