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Biomedical subjects

R White

Publications and source records attributed to R White.

At least 595 records · Page 33Linked to original sources
PubMed1987

Characterization of a human 'midisatellite' sequence.

We have examined the structure and DNA sequence of a human genomic locus that consists of a large hypervariable region made up of repeats of a simple sequence. With several restriction enzymes, the locus shows many restriction fragments that vary quantitatively as well as qualitatively. Other restriction enzymes produce only a single, high-molecular-weight fragment at this locus. Almost all of the fragments are revealed with a simple sequence probe. Southern transfers of the high-molecular-weight restriction fragments produced by the restriction enzymes NotI and SfiI, resolved by pulsed-field gel electrophoresis, gave at most two fragments, demonstrated to be allelic, showing that the majority of the restriction fragments seen in the complex patterns are at a single locus. The estimated size of the region homologous to the probe varied from 250 to 500 kilobases. DNA sequencing indicated that the region consists of tandem repeats of a 40-base-pair sequence. Some homology was detected to the tandem repeating units of the insulin gene and the zetaglobin pseudogene hypervariable regions, and to the "minisatellite" DNA at the myoglobin locus.

Base Sequence↗
PubMed1987

Identification of androgen response elements in mouse mammary tumour virus and the rat prostate C3 gene.

The effect of steroid hormones on mouse mammary tumour virus (MMTV) promoter activity has been analysed in the breast cancer cell lines ZR-75-1 and T-47D 11. Both androgens and progestins were stimulatory in both cell lines, whereas glucocorticoids were stimulatory in only ZR-75 cells. A glucocorticoid response was restored to T-47D cells by the transient expression of a glucocorticoid receptor expression vector, suggesting that endogenous receptors were limiting. The effect of androgen was mediated by a region of MMTV previously shown to be essential for glucocorticoid and progestin responses between nucleotides -201 and -69 upstream of the cap site. Similarly, the effect of androgens on the rat prostate C3(1) gene promoter was analysed in the rat prostate cell line T5. Although these cells had functional androgen receptors which could stimulate MMTV-promoter activity, they were incapable of interacting with androgen response elements to stimulate transcription from the C3(1) promoter.

Androgens↗
PubMed1987

Tightly linked markers for the neurofibromatosis type 1 gene.

Relationships among genetic markers in the region of the neurofibromatosis type 1 (NF1) gene on chromosome 17 were investigated by linkage studies in a large sample set of affected families and in a panel of 58 normal families. A new marker, pHHH202 (D17S33), was included along with two markers known to be closely linked to NF. The maximum likelihood estimate of the recombination rate between the pHHH202 and NF1 loci was found to be O. Multilocus analysis suggested the following marker order: pA10-41-(p3-6, pHHH202); the NF1 gene fell with equal likelihood between either pA10-41-p3-6 or p3-6-pHHH202. The odds against NF1 being outside this cluster of tightly linked markers were greater than 15:1.

Chromosome Mapping↗
PubMed1987

Linkage, physical mapping, and DNA sequence analysis of pseudoautosomal loci on the human X and Y chromosomes.

The pseudoautosomal region of the human X and Y chromosomes is subject to frequent X-Y recombination during male meiosis. We report the finding of two pseudoautosomal loci, DXYS20 and DXYS28, characterized by highly informative restriction fragment length polymorphisms (RFLPs). The pseudoautosomal character of DXYS20 and DXYS28 was formally demonstrated by comparing their transmission to 45,X and to normal individuals. Studies of the inheritance of these loci reveal that the pseudoautosomal region, though highly recombinogenic, is subject to marked recombinational interference in male meiosis; no double recombinants were observed in 143 triply informative meioses, and the coefficient of coincidence is likely less than 0.45. In female meiosis, linkage of these pseudoautosomal RFLPs to strictly sex-linked RFLPs on the short arm of the X is readily detected; the genetic length of the pseudoautosomal region in female meiosis is at least 4 cM but not more than 18 cM. The genetic map of the human X chromosome is now defined from near the short-arm telomere to band q28 on the long arm. Locus DXYS20, which maps near the X and Y short-arm telomeres, is composed of long tandem arrays of 61-bp repeats. Occasional, seemingly random base-pair substitutions within these arrays of 61-bp repeats, in combination with marked variation in the size of the array, generate the high degree of DNA polymorphism at DXYS20.

Base Sequence↗
PubMed1987

Three additional DNA polymorphisms in the met gene and D7S8 locus: use in prenatal diagnosis of cystic fibrosis.

We have used cloned DNA sequences from the 5' end of the met locus and the D7S8 locus to locate new restriction fragment length polymorphisms. TaqI and MspI polymorphisms with frequencies of 0.34/0.66 and 0.10/0.90, respectively, for met and a PvuII polymorphism (0.15/0.85) at D7S8 are described. We used these new markers to analyze our reference panel of cystic fibrosis pedigrees and found that they provided additional information in several families. No evidence for recombination was observed between the 5' end of met and previously described met markers. We present examples of the use of the met markers in the clinical diagnosis of cystic fibrosis and summarize our analysis of 29 clinical cases including eight prenatal diagnoses. We conclude that DNA-based prediction of cystic fibrosis is an effective clinical diagnostic procedure.

Alleles↗
PubMed1987

Cloning of partial cDNA encoding differentiation and tumor-associated mucin glycoproteins expressed by human mammary epithelium.

Human mammary epithelial cells secrete and express on their cell surfaces complex mucin glycoproteins (Mr greater than 250,000) that are developmentally regulated, tumor-associated, and highly immunogenic. Studies using monoclonal antibodies directed to these glycoproteins suggest that their molecular structures can vary with differentiation stages in the normal gland and in malignancy. To analyze the molecular nature of these glycoproteins, milk mucin was affinity-purified and deglycosylated with hydrogen fluoride, yielding bands at 68 and 72 kDa on silver-stained gels. Polyclonal and monoclonal antibodies to the stripped core protein were developed and used to screen a lambda gt11 expression library of cDNA made from mRNA of the mammary tumor cell line MCF-7. Seven cross-reacting clones were isolated, with inserts 0.1-1.8 kilobases long. RNA blot analysis, using as a probe the 1.8-kilobase insert subcloned in plasmid pUC8 (pMUC10), revealed transcripts of 4.7 and 6.4 kilobases in MCF-7 and T47D mammary tumor cells, whereas normal mammary epithelial cells from pooled milks have additional transcripts. The expression of mRNA correlates with antigen expression as determined by binding of two previously characterized anti-mucin monoclonal antibodies (HMFG-1 and HMFG-2) to seven cell lines. Restriction enzyme analysis detected a restriction fragment length polymorphism when human genomic DNA was digested with EcoRI or HinfI.

Antibodies, Monoclonal↗
PubMed1987

Quantitative determination of tolazoline in human serum by high performance liquid chromatography.

A micro high performance liquid chromatography assay is reported for the measurement of tolazoline in newborn infants. Pharmacokinetic data are presented for a single infant receiving tolazoline therapy. Tolazoline and the internal standard, clonidine, are extracted from alkaline serum into butylchloride/isopropanol (95/5). The organic layer is then back extracted with 50 mM phosphoric acid. A portion of the phosphoric acid layer is injected onto a 15-cm CN-bonded phase column. A mobile phase consisting of acetonitrile and phosphate buffer (pH 3) is used to elute tolazoline and the internal standard in less than 5 min. The effluent is monitored with a fixed wavelength detector at 214 nm. Using 50 microliters of serum, concentrations as low as 0.25 mg/L can be routinely determined with a coefficient of variation (CV) of 7.2%. However, when a 100-microliters sample is used, and the injection volume increased, a concentration of 0.05 mg/L can be routinely monitored with a CV of 1.2%. Interference from other drugs that are often used concurrently with tolazoline therapy was not observed.

Chromatography, High Pressure Liquid↗
PubMed1987

The preventive effect of verapamil on ethanol-induced cardiac depression: phosphorus-31 nuclear magnetic resonance and high-pressure liquid chromatographic studies of hamsters.

Alcoholic depression of left ventricular function was produced in normal hamsters by the administration of increasing concentrations of alcohol in drinking water (up to 50%) for 6 months. The result was assessed by phosphorus-31 nuclear magnetic resonance of isolated perfused hearts and high-pressure liquid chromatography of freeze-clamped tissues. Hemodynamic data and myocardial oxygen consumption were also monitored. Alcoholic hamsters had significantly higher inorganic phosphate and lower ATP levels, while maintaining normal intracellular pH, phosphocreatine, and creatine. Although coronary flow and oxygen consumption were maintained at normal levels, hamsters ingesting 50% ethanol had significantly lower left ventricular developed pressure and dP/dt. Treatment with verapamil during long-term ethanol consumption prevented the development of these metabolic and functional abnormalities. It is hypothesized that alcohol produces membrane abnormalities leading to adverse ion flux, and that these are largely prevented by concurrent administration of verapamil.

Adenosine Triphosphate↗
PubMed1987

A double-blind crossover trial of diflunisal and naproxen in osteoarthritis.

Fifty patients with osteoarthritis were studied in a double-blind, crossover trial of diflunisal (1000 mg daily) and naproxen (750 mg daily). In the 45 patients who completed the study, no significant difference was noted between the drugs in most of the parameters studied, including evening pain intensity and effectiveness rating by patient and investigator. There was a trend towards greater patient preference for diflunisal, although this trend did not reach statistical significance. Naproxen produced significantly fewer side-effects, although side-effects with both drugs were mild.

Adult↗
PubMed1987

Structural organization and expression of the mouse estrogen receptor.

Complementary DNA clones corresponding to the mouse uterus estrogen receptor mRNA have been isolated and characterized. Nucleotide sequence analysis predicts that full-length cDNA has the potential to code for a polypeptide of 599 amino acids, and comparison with the protein sequences of the rat, human, and chicken estrogen receptors reveals overall homologies of 97%, 88% and 77%, respectively. Genomic clones for the mouse estrogen receptor have been isolated from a cosmid library and used in conjunction with the cDNA clones to study the expression of the receptor in vivo by RNase mapping, primer extension, and Northern blotting. These analyses demonstrate that transcription initiates at multiple sites which span a region of at least 62 base pairs and that the estrogen receptor is encoded by mRNA of approximately 6.5 kilobases in size. There are 10 major starts in total, one of which is situated 31 nucleotides downstream from a TATA box-like motif and coincides with the start of the cDNA clone pMOR8. The ability of the cDNA clone to produce a functional protein was verified by transfection into COS-1 cells which lack endogenous estrogen receptor. The mouse estrogen receptor, in a SV40-based expression vector, was cotransfected with a chimeric marker plasmid consisting of an estrogen response element from the vitellogenin A2 gene linked to the thymidine kinase promoter and the chloramphenicol acetyl transferase gene. In the presence of estradiol chloramphenicol acetyl transferase activity is stimulated by up to 80-fold, while tamoxifen and 4-hydroxytamoxifen act primarily as antiestrogens in this in vitro assay.

Amino Acid Sequence↗