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Biomedical subjects

T Davis

Publications and source records attributed to T Davis.

At least 127 records · Page 7Linked to original sources
PubMed1991

The cervical cap.

The cervical cap is a barrier contraceptive method with an efficacy similar to that of the diaphragm. It has several advantages over other barrier contraceptives. In particular, it can be left in place for up to 48 hours, and repeated applications of spermicide are not necessary, even if sexual intercourse occurs more than once. In addition, the side effects seen with other barrier methods do not occur with the cervical cap. In some women, Papanicolaou tests may become abnormal, especially during the first three months of cap use. Therefore, careful monitoring of cervical cap users is essential.

Contraceptive Devices, Female↗
PubMed1990

Expression cloning of a human granulocyte colony-stimulating factor receptor: a structural mosaic of hematopoietin receptor, immunoglobulin, and fibronectin domains.

We report the isolation from a placental library, of two cDNAs that can encode high affinity receptors for granulocyte colony-stimulating factor (G-CSF) when expressed in COS-7 cells. The cDNAs are predicted to encode integral membrane proteins of 759 and 812 amino acids in length. The predicted extracellular and membrane spanning sequences of the two clones are identical, as are the first 96 amino acids of their respective cytoplasmic regions. Different COOH termini of 34 or 87 residues are predicted for the two cDNAs, due apparently to alternate splicing. The receptor with the longer cytoplasmic domain is the closest human homologue of the murine G-CSF receptor recently described by Fukunaga et al. (Fukunaga, R., E. Ishizaka-Ikeda, Y. Seto, and S. Nagata. 1990. Cell. 61:341). A hybridization probe derived from the placental G-CSF receptor cDNA detects a approximately 3-kb transcript in RNAs isolated from placenta and a number of lymphoid and myeloid cells. The extracellular region of the G-CSF receptors is composed of four distinct types of structural domains, previously recognized in other cell surface proteins. In addition to the two domains of the HP receptor family-defining region (Patthy, L. 1990. Cell. 61:13) it incorporates one NH2-terminal Ig-like domain, and three additional repeats of fibronectin type III-like domains. The presence of both an NH2-terminal Ig-like domain and multiple membrane-proximal FN3-like domains suggests that the G-CSF receptor may be derived from an ancestral NCAM-like molecule and that the G-CSF receptor may function in some adhesion or recognition events at the cell surface in addition to the binding of G-CSF.

Amino Acid Sequence↗
PubMed1990

A receptor for tumor necrosis factor defines an unusual family of cellular and viral proteins.

Tumor necrosis factor alpha and beta (TNF-alpha and TNF-beta) bind surface receptors on a variety of cell types to mediate a wide range of immunological responses, inflammatory reactions, and anti-tumor effects. A cDNA clone encoding an integral membrane protein of 461 amino acids was isolated from a human lung fibroblast library by direct expression screening with radiolabeled TNF-alpha. The encoded receptor was also able to bind TNF-beta. The predicted cysteine-rich extracellular domain has extensive sequence similarity with five proteins, including nerve growth factor receptor and a transcriptionally active open reading frame from Shope fibroma virus, and thus defines a family of receptors.

Amino Acid Sequence↗
PubMed1990

The molecular analysis of the el-noc complex of Drosophila melanogaster.

The el-noc complex spans a distance of about 200 kb on chromosome 2L. It consists of three discrete genetic regions el, l(2)35Ba and noc, each of which has a distinct phenotype when mutant. The noc locus itself is complex, including three separate regions. The el locus has been characterized by mapping 30 aberration breakpoints to the DNA. It extends over a distance of about 80 kb. It can be divided into two parts by the aberrations In(2LR)DTD128 and T(Y;2)A80. These break between two sets of el alleles yet are both phenotypically wild type for elbow. The simplest explanation is that el consists of two transcription units elA and elB. The locus pu, which appears to be unrelated to the el-noc complex, is found to map between the two el loci very close to elB (the distal el locus). The loci l(2)35Ba and nocA have been separated by only two l(2)35Ba+nocA- deletions and a nocA- inversion. No l(2)35Ba-nocA+ aberrations have been found. At the molecular level these loci are found to occupy almost the same region, and are probably identical.

Animals↗
PubMed1990

A novel transvection phenomenon affecting the white gene of Drosophila melanogaster.

The zeste mutation of Drosophila melanogaster suppresses the expression of white genes in the eye. This suppression is normally dependent on there being two copies of w+ located close to each other in the genome--they may either be in cis (as in a tandem duplication of w+) or in trans, i.e. on homologous chromosomes. Duplicated w+ genes carried by a giant transposing element, TE146(Z), are suppressed by z whether they are in direct (tandem) or inverted order. The tandem form of the TE is very sensitive to a rearrangement on the homologous chromosome--many rearrangements with breakpoints "opposite" the TE's insertion site prevent the interaction between the white genes on a z background. These aberrations act as dominant suppressors of zeste that are specific to the tandemly duplicated form of TE146(Z). The inverted form of the TE146(Z) presumably pairs as a hairpin loop; this is more stable than the tandem form by the criterion that its zeste phenotype is unaffected by any of the aberrations. This effect of rearrangements has been used as the basis for a screen, gamma-ray induced aberrations with at least one breakpoint opposite the TE site were recovered by their suppression of the zeste phenotype.

Animals↗
PubMed1990

Temperature sensitivity of equine herpesvirus isolates: a brief review.

This article reviews the findings on temperature sensitivity of equine herpesvirus isolates with an emphasis on equine herpesvirus 3, etiological agent of equine coital exanthema. The hypothesis is presented that the relative apathogenic nature of this herpesvirus may be an indirect result of its inability to synthesize and/or process glycoproteins needed by the virus to produce infectious virions at the normal body temperature of its natural host. It is suggested that equine herpesvirus 3 is the more evolved and naturally attenuated member of the equine herpesviruses.

Animals↗
PubMed1990

Primary adrenal insufficiency: a new cause of reversible gastric stasis.

Primary adrenal insufficiency is known to cause a wide spectrum of sometimes severe upper gastrointestinal symptoms; however, it has not previously been shown to be the cause of reversible gastric stasis. We have documented such a case in which the symptoms and physiologic abnormalities associated with gastric stasis were reversed by steroid replacement. A follow-up radionuclide gastric-emptying study after physiologic steroid replacement showed complete normalization of gastric emptying. Although gastric stasis has long been suspected of being present with primary adrenal insufficiency, this represents the first case in which it has been documented, and so should be included in the differential diagnosis of patients presenting with chronic nausea and vomiting.

Adrenal Cortex Diseases↗
PubMed1989

The undiluted message in psychiatry: is medical rounding valuable?

The present research investigated whether psychiatric inpatients would recall, without distortion, the key components of information presented to them during morning rounds. Over the 4 weeks of the study, the messages of rounding psychiatrists were recorded and then compared with the recollections of 16 subjects recorded several hours later. Analysis showed that undistorted recall of messages occurred significantly more often than distorted recall or no recall. These results suggest that there is a possible value for undiluted messages in medical rounding in the inpatient psychiatric context when given as an adjunct to psychotherapeutic and psychopharmacological interventions.

Humans↗
PubMed1989

Do inhibitors of lipoxygenase and cyclooxygenase block neonatal hypoxic pulmonary vasoconstriction?

Lipoxygenase products have been suggested as mediators of the hypoxic pulmonary pressor response in newborn animals. Data supporting this suggestion are equivocal, since lipoxygenase and leukotriene receptor antagonists that have been used may produce vasodilation because of phosphodiesterase inhibition. We used a leukotriene receptor antagonist L 649923, which appears not to have smooth muscle relaxant activity. L 649923 blocks pressor responses to leukotriene D4 (LTD4) without diminishing the pressor response to hypoxia. Also, BW 755C did not block the pressor response to hypoxia in newborn sheep and goats, whereas the pressor response to LTD4 (75 ng/kg) was depressed significantly. In newborn sheep there was an augmented response to hypoxia with BW 755C, which is consistent with cyclooxygenase inhibition. Finally, the thromboxane receptor antagonist SQ 29548 was investigated in both species. With this agent the pressor response to LTD4 in contrast to that of hypoxia was completely inhibited. We conclude that thromboxanes are involved in the pressor response to LTD4 in newborn lambs and goats. These data do not support the view that leukotrienes are involved in the ovine or caprine neonatal pulmonary pressor response to hypoxia.

4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyraz↗
PubMed1989

Endoscopic injection therapy for acute upper GI bleeding.

In summary, we have found this technique to be useful in patients in whom coagulation therapy is not possible or effective. It must still be considered a technique which is undergoing evaluation. Prospective randomized trials comparing this therapy with other currently available therapies such a electrocoagulation, laser and conservative management must be completed to firmly define its place in treatment strategy for acute upper GI bleeding.

Aged↗
PubMed1989

Occurrence of Culex erythrothorax in southeastern Colorado and report of virus isolations from this and other mosquito species.

Significant numbers of Culex erythrothorax were collected during arbovirus surveillance in 1987 and 1988 at Las Animas, Bent County, on the high plains of southeastern Colorado. This finding extends the range of this species to the eastern side of the Rocky Mountains. The isolation of western equine encephalitis virus in 1988 from both Cx. tarsalis and Cx. erythrothorax suggests that the latter also may be involved in the endemic cycle of this virus in the area. St. Louis encephalitis, Hart Park, Turlock, and a Bunyamwera group virus were also isolated from the mosquitoes collected.

Aedes↗
PubMed1988

Nucleotide sequence of the mannitol (mtl) operon in Escherichia coli.

The nucleotide sequence of the known portions of the mannitol operon in Escherichia coli (mtlOPAD) has been determined. Both the operator-promoter region and the intercistronic region between the mtlA and mtlD genes (encoding the mannitol-specific Enzyme II of the phosphotransferase system and mannitol-1-phosphate dehydrogenase, respectively) show parallels with corresponding regions of the glucitol (gut) operon, but neither the mtlA nor the mtlD gene products show obvious homology with the corresponding gene products of the glucitol operon. Five potential cyclic AMP receptor protein binding sites were identified in the mtlOP region, all showing near identity with the consensus sequence. Four regions of dyad symmetry (four to seven bases in length), serving as potential repressor binding sites, overlap with the potential cyclic AMP receptor protein binding sites. Repetitive extragenic palindromic (REP) sequences, forming stem-loop structures in the intercistronic region between mtlA and mtlD and following the mtlD gene were identified. Probable terminator sequences were not found in any of these three regulatory regions. Mannitol-1-phosphate dehydrogenase exhibits two overlapping, potential NAD+ binding sites near the N-terminus of the protein. Computer techniques were used to analyse the mtlD gene and its product.

Amino Acid Sequence↗
PubMed1987

CpG deficiency, dinucleotide distributions and nucleosome positioning.

The dinucleotide CpG is deficient in (A + T)-rich regions of vertebrate DNA in both coding and non-coding sequences and there is a corresponding increase above expectation in the occurrence of TpG and CpA. By contrast in (G + C)-rich regions no deficiency of CpG is found. Such (G + C)-rich sequences, containing the expected number of CpG dinucleotides, alternate along the genome with (A + T)-rich sequences which have a lower than expected CpG content. The G + C content of vertebrate DNA can oscillate with a period of 150-200 bp and this may be a factor in positioning nucleosomes. The role of mutagenesis in loss of CpG and increase of A + T, particularly in non-coding regions, is discussed.

Base Composition↗
PubMed1987

Pulmonary aspergillosis: unusual radiographic appearance.

Three cases of pulmonary aspergillosis are reported in which a seldom-mentioned radiographic feature was seen, namely, a stable, well-defined nodule or mass. The diagnosis of aspergillosis was based on results of transthoracic needle aspiration biopsy. Computed tomographic scans obtained before biopsy revealed no evidence of underlying cavitary disease. Two patients had hemoptysis. The nodule in the third patient was found on a routine chest radiograph.

Aged↗
PubMed1987

Glycogen-rich clear cell carcinoma of the urethra: an ultrastructural study.

A 49-year-old black woman developed a urethral glycogen-rich clear cell carcinoma. She was treated with anterior pelvic exenteration. The resected lymph nodes, vagina, uterine cervix, endometrium, ovaries, and urinary bladder were free of neoplasm. Histologically the neoplasm consisted of clear cells growing in sheets and occasional papillary structures. In some areas, hobnail cells were present. Ultrastructurally, the cells had apical caps, short microvilli, and complex cell bases, and contained abundant glycogen. These features were identified in one, but not the other of two previously reported cases. Because glycogen-rich clear cell carcinomas of the lower urinary tract do not resemble ultrastructurally mesonephric remnants or carcinomas known to arise from them, these glycogen-rich clear cell carcinomas should not be called "mesonephromas" as has been the practice.

Adenocarcinoma↗
PubMed1987

Epizootic vesicular stomatitis in Colorado, 1982: epidemiologic and entomologic studies.

An epizootic of vesicular stomatitis (VS) caused by the New Jersey serotype of VS virus affected livestock and humans in 14 western states in 1982-1983. Epidemiological observations were made on at least 10% of the cattle in 4 dairy herds that were located in the vicinity of Grand Junction, Colorado. High rates of neutralizing antibody to the New Jersey serotype were seen in all cattle regardless of whether livestock in the dairy had clinical VS or a decrease in mild production. Antibody titers remained high in these cattle for as long as 2 years after the epizootic. No virus isolations were made from 32 humans with clinical signs compatible with viral disease. Entomological information was obtained during the epizootic from 23 premises in northwestern Colorado. Insect collections yielded 4 isolates from Culicoides spp. midges, 2 from C. variipennis, and 1 each from C. stellifer and C. (Selfia) spp. This is the first report of VS virus isolations from field-collected Culicoides.

Aedes↗
PubMed1987

Classification of type III (severe) open fractures relative to treatment and results.

Severe type III open fractures were subtyped according to the differences in prognosis for sepsis, amputation, and treatment: IIIA (adequate soft-tissue coverage of bone with extensive soft-tissue laceration or flaps), IIIB (extensive soft-tissue loss with periosteal stripping and bone exposure), and IIIC (arterial injury requiring repair). Analysis of 303 open fractures revealed a sepsis rate of 0% in type I, 2.5% in type II, and 13.7% in type III. The rate of amputation was 18.7%, and the rate of nonunion was 18.5% in type III open fractures. Type IIIA, IIIB, and IIIC open fractures had sepsis rates of 5%, 28%, and 8%, and amputation rates of 2.5%, 5.6%, and 25%, respectively. The overall wound sepsis rate in the 303 open fractures was 4.4%, and the nonunion rate was 8.6%.

Amputation, Surgical↗