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D Wells

Publications and source records attributed to D Wells.

At least 19 recordsLinked to original sources
PubMed1992

Closely linked H2B genes in the marine copepod, Tigriopus californicus indicate a recent gene duplication or gene conversion event.

Two nonallelic histone gene clusters were characterized in the marine copepod, Tigriopus californicus. The DNA sequence of one of the clusters reveals six genes in the contiguous arrangement of H2B, H1, H3, H4, H2B and H2A. The order of genes within the second cluster is H3, H4, H2B and H2A. There is no evidence for the presence of an H1 gene in this cluster. Comparison of the three copepod H2B genes reveals a high degree of similarity between the 5' upstream regions and between the amino terminal halves of the two H2B genes found within the same cluster. From these data we infer that gene duplication and/or gene conversion events occurred within this cluster in the recent past.

Alleles↗
PubMed1991

Method for separation and determination of lactone and hydroxy acid forms of a new HMG CoA reductase inhibitor (RG 12561) in plasma.

The new drug RG 12561 (I) is a lactone that is undergoing clinical evaluation for its cholesterol lowering effect based on potent HMG CoA reductase inhibitory activity displayed by its open hydroxy acid form. To determine the dispositional characteristics of the drug, a method was developed for determination of the two forms in plasma. A 0.25-ml aliquot of plasma was deproteinized with 0.5 ml of methanol, and the lactone was extracted with hexane-ethyl acetate (75:25, v/v). The methanolic plasma was then acidified followed by extraction of the hydroxy acid with hexane-ethyl acetate. The extracts were dried, reconstituted and analyzed by isocratic, reversed-phase high-performance liquid chromatography using ultraviolet absorbance at 254 nm. The separations were performed utilizing a C18 column with mobile phase consisting of acetonitrile, 2-propanol and 0.1 M acetate buffer (pH 5), the proportions of which differed depending on the form of drug analyzed. The method was found to be selective and a quantitation limit of 50 ng/ml was established. Validation studies demonstrated that the method was sufficiently accurate and precise for determining disposition of the drug in the dog.

Animals↗
PubMed1991

An H3-H4 histone gene pair in the marine copepod Tigriopus californicus, contains an intergenic dyad symmetry element.

Histone genes are one of the most widely studied multigene families in eucaryotes. Over 200 histone genes have been sequenced, primarily in vertebrates, echinoderms, fungi and plants. We present here the structure and genomic orientation of an H3-H4 histone gene pair from the marine copepod, Tigriopus californicus. These histone gene sequences are the first to be determined for the class Crustacea and among the first to be determined for protostomes. The H4 and H3 genes in Tigriopus are shown to be adjacent, to have opposite polarity, and to contain a 26 bp region of dyad symmetry centrally located within the spacer region between the two genes. A similarly located dyad element has been found in yeast which contributes to the coordinated cell cycle control of the adjacent histone genes. The Tigriopus H3-H4 histone gene pair is clustered with one H2A and two H2B histone genes on a 15 kb genomic Bam H1 fragment. The H4 gene sequence predicts an H4 protein with an unusual serine to threonine substitution at the amino terminal residue. The H3 gene sequence predicts an H3 protein which is identical to the vertebrate H3.2 histone.

Amino Acid Sequence↗
PubMed1991

Characterization of an unusual human histone H3.3 pseudogene.

The analysis of a genomic loci containing human histone H3.3 processed pseudogenes, has revealed two regions that are unusually rich in other retroposons. At one of the loci the H3.3 pseudogene is itself interrupted by 2 Alu repetitive sequences. The characterization of these two recently transposed Alus provides confirmation of the "multiple origin" hypothesis of these repetitive elements. The unusual occurrence of 3 different types of retroposons in a small region suggests that there may be particular chromosomal regions that are hot spots for retroposon insertion.

Base Sequence↗
PubMed1990

Learning styles and learning preferences of first and fourth semester baccalaureate degree nursing students.

Learning styles and preferred learning approaches are believed to have an influence on student learning. This study compared the learning styles and learning preferences of first and fourth semester baccalaureate nursing students, as well as explored changes in learning styles and learning preferences from first to fourth semester. The two predominant learning styles of both groups of students were Abstract Random and Concrete Sequential. According to Gregorc, (1982a), these learning styles are on the opposite poles in relation to perceiving and ordering information. No significant changes were found in learning style scores from first to fourth semester. Students indicated a range of preferences for 12 learning methods. Mean scores on three methods (slide/filmstrip, short lecture with question and answer, television/movies) dropped significantly from first to fourth semester. Implications for nursing education are discussed.

Choice Behavior↗
PubMed1989

The effect of the intrauterine contraceptive device on endometrial secretory function: a possible mode of action.

The effect of the intrauterine contraceptive device (IUD) on the composition of endometrial secretion has been studied using the monoclonal antibody D9B1. The antibody binds to a polypeptide-associated oligosaccharide epitope that is secreted by endometrial epithelium in the secretory phase with a maximum around the time of implantation. In endometria affected by the IUD in situ, a significant reduction in epitope expression has been observed using immunohistochemistry. This defect can occur against a background of normal secretory differentiation and in the expectation of normal ovarian stimulus. The data provide new insight into the contraceptive mechanisms of action of the IUD.

Adult↗
PubMed1988

Tolerance and efficacy of recombinant human interferon gamma in the treatment of refractory genital warts.

PURPOSE: The intralesional administration of recombinant interferon alpha has led to resolution of genital warts in 50 to 70 percent of cases. However, continuous warts do not respond to such treatment, and human papillomavirus (HPV) infection of other anatomic sites remains untreated, so infection may continue to be transmitted. Since interferons have shown promise as effective therapies for genital warts, we decided to investigate the tolerance and efficacy of recombinant human interferon gamma in the treatment of refractory genital warts. PATIENTS AND METHODS: Nineteen women and nine men with refractory genital warts were treated in an open-label, dose-response trial of intramuscular recombinant human interferon gamma. RESULTS: Complete responses were seen in two (7 percent) and partial responses were seen in 13 (46 percent). Of 12 women with concomitant cervical HPV infection, eight demonstrated resolution with therapy. Response rates were higher in those patients who had warts less than nine months (73 percent) prior to therapy and in women (63 percent). Responses were not associated with HPV type. Flu-like symptoms during treatment were frequent but well tolerated. Transient abnormal laboratory results were more frequent with daily administration than with three times weekly therapy. Eleven of 16 subjects treated with cryotherapy after treatment with interferon experienced long-term remissions. CONCLUSIONS: In ambulatory patients with refractory genital warts, recombinant human interferon gamma appears to be biologically active and to have few adverse effects. The high efficacy rate achieved in subjects treated with cryotherapy after treatment with interferon suggests that further studies of combination therapy with these modalities are warranted.

Adolescent↗