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Biomedical subjects

T Davis

Publications and source records attributed to T Davis.

At least 109 records · Page 6Linked to original sources
PubMed1993

Comparative morphine pharmacokinetics following sublingual, intramuscular, and oral administration in patients with cancer.

Previous literature reports have suggested that sublingually administered morphine sulfate results in an improved bioavailability of the drug when compared to orally administered morphine. To investigate this possibility further, we studied six cancer patients all of whom received 10 mg doses of morphine sulfate by intramuscular, oral and sublingual routes. Pharmacokinetic analyses failed to suggest an advantage of sublingual administration when compared with oral dosing. Bioavailability of morphine following intramuscular administration appeared superior to both oral and sublingual routes.

Administration, Oral↗
PubMed1993

Arbovirus surveillance in northern Colorado, 1987 and 1991.

Arbovirus surveillance was conducted during an epizootic of western equine encephalitis (WEE) during 1987 and during a nonepizootic year, 1991, in the same area in northern Colorado. Mosquitoes were collected in Larimer County, CO, during weeks 33-37 (10 August to 7 September) in 1987 and during weeks 26-35 (24 June to 26 August) in 1991. In total, 13,099 mosquitoes in 694 pools collected during 1987 and 8,672 mosquitoes in 242 pools collected during 1991 were tested for virus. WEE virus was isolated in both years from Culex tarsalis Coquillett and from Cx. pipiens L. in 1987. Infection rates and population levels of Cx. tarsalis were not significantly different in the 2 yr during weeks 33, 34, and 35 (12-26 August). St. Louis encephalitis virus was isolated in 1987 from Cx. tarsalis. Other viruses isolated included Hart Park, Turlock, and Jerry Slough, a variety of Jamestown Canyon virus.

Aedes↗
PubMed1993

The gene therapy of cancer: transgenic immunotherapy.

Gene therapy can be defined as the insertion of functional genes into cells to treat a disease. Cellular augmentation, whereby gene transfer confers a novel function to the cell, has proved to be useful in designing strategies for the treatment of cancer. In particular, a variety of cell types may be transduced with immune response genes that are intended to elicit a more effective immune attack against tumor cells. This process has been termed transgenic immunotherapy. Preclinical studies involving the transduction of tumor cells, stromal cells, and lymphocytes with a number of immune response genes have demonstrated potent cytotoxic lymphocyte responses against tumor cells, and in some cases the induction of long-lasting immunity against tumor rechallenge. It is hoped that this form of cancer immunotherapy will permit the development of vaccines effective in eradicating minimal residual disease and immunizing individuals at risk for cancer.

Animals↗
PubMed1993

Endometriosis of the small intestine presenting as a protein-losing enteropathy.

A 46-yr-old multiparous cachetic woman presented with severe hypoalbuminemia in the absence of liver disease, proteinuria, and/or protracted starvation. The clinical presentation and work-up was indicative of protein-losing enteropathy. She developed an acute partial small bowel obstruction, and a presumptive diagnosis of lymphoma of the small intestine was entertained. Surgical resection of the terminal ileum revealed transmural involvement of the bowel by endometriosis. Her postoperative recovery was uneventful, with return of her serum albumin levels to normal.

Diagnosis, Differential↗
PubMed1992

Synthesis of [D-Ala2,4'-125I-Phe3,Glu4]deltorphin and characterization of its delta opioid receptor binding properties.

Both [D-Ala2,Glu4]Deltorphin and [D-Ala2,4'-I-Phe3,Glu4]Deltorphin are highly selective ligands for delta, relative to mu, opioid receptors. Radiolabeled [D-Ala2, 4'-125I-Phe3,Glu4]Deltorphin ([125I]Deltorphin) was prepared with a specific activity of 2200 Ci/mmol from [D-Ala2, 4'-NH2-Phe3, Glu4]Deltorphin through a diazonium salt intermediate. The inhibition of [125I]Deltorphin binding to rat brain membranes by ligands selective for mu, delta, and kappa opioid receptors is consistent with binding by the radioligand to a single site having the properties of a delta opioid receptor. The results of these studies are in good agreement with those obtained by structurally different delta opioid receptor ligands. The similarity between the delta receptor site labeled by [125I]Deltorphin and those labeled by other delta receptor agonists, in contrast to differences seen by in vivo studies of their analgesic effects, is discussed.

Animals↗
PubMed1992

Trisomy 15 mosaicism in an IVF fetus.

Prenatal diagnosis of an IVF pregnancy in a woman aged 41 years showed a fetus mosaic for trisomy 15. The fetus had dysmorphic features, hypoplastic adrenal glands, and an accessory spleen. Both IVF and advanced maternal age would seem to increase the risk of trisomy 15.

Abortion, Eugenic↗
PubMed1992

Recognizing panic in cardiac patients.

Patients presenting with apparent myocardial infarctions may in fact be suffering from panic attacks; many symptoms of the latter mimic those of the former. Cardiovascular nurses who know what to listen for in patients' descriptions can recognize indications that panic may be occurring. This article describes panic attacks, panic disorder, and the long-term consequences that often accrue when this highly treatable problem is not recognized. Particularly when no evidence of myocardial damage is found, a cardiovascular nurse's recognition of panic can lead to a referral for appropriate psychological treatment, preventing years of needless suffering and unnecessary health care costs.

Female↗
PubMed1991

T2 open reading frame from the Shope fibroma virus encodes a soluble form of the TNF receptor.

A transcriptionally active open reading frame (T2) from Shope Fibroma Virus was recently shown to have striking sequence homology with members of a new superfamily of cell surface proteins, including a receptor for human tumor necrosis factor. Here we report that recombinant T2 protein expressed in COS cells is a soluble, secreted glycoprotein which specifically binds human TNF alpha and beta, and inhibits binding of these cytokines to native TNF receptors on cells. T2 binding of TNF is not inhibited by nerve growth factor, although the nerve growth factor receptor is also a member of the same family, nor by nine other recombinant cytokines. Further, the repeating domain structure of T2 most closely resembles that of the type I TNF receptor (p75) and is significantly different from other family members, including the type II TNF receptor (p55). Since T2 possesses a leader sequence but lacks a transmembrane domain, these results confirm the original suggestion (1) that T2 represents a soluble form of the type I TNF receptor which is secreted from virally infected cells, and whose function is to immunosuppress the host by abrogating the potentially destructive effects of TNF. This is the first such virally-encoded soluble cytokine receptor to be identified, and may represent a more general mechanism by which viruses subvert the host immune system.

Amino Acid Sequence↗
PubMed1991

Venous valvular insufficiency: influence of a single venous valve (native and experimental).

This report evaluates the ability of a single competent (native or experimental) superficial femoral vein valve to correct canine hindlimb venous insufficiency. The time to maximal ankle venous pressure after standing (VFT) and to 90% of that time after exercise (VRT90), and the minimal pressure after exercise (AVP) were measured in 17 greyhounds before intervention, after only the superficial femoral vein valve remained (n = 5), and after complete lower limb venous valvulotomy (n = 17). Three weeks later, 12 dogs underwent a native (n = 4) or experimental (n = 8) autogenous venous valve transplantation. Immediately and at 3 weeks after transplantation, venous pressure measurements were obtained. The manual strip test confirmed valve competence at the time of sacrifice. Only one valve transplant became incompetent. Immediately after single superficial femoral vein valve construction, VFT, AVP, and VRT90 measurements were not significantly different from normal. Three weeks after transplantation the AVP measurements were consistent with an insufficient venous system, whereas the VRT90 measurements were between and statistically different from both the control and totally incompetent system (p less than 0.05). After the native valve but not the experimental valve transplantations VFT normalized. These data suggest that insertion of a single competent superficial femoral vein valve into an incompetent lower limb venous system corrects venous pressure measurements initially but soon provides only a partially competent system. The experimental valve, although competent, is less responsive than a native valve.

Animals↗
PubMed1991

Molecular cloning and expression of the type 1 and type 2 murine receptors for tumor necrosis factor.

Clones encoding the type 1 (p80) and type 2 (p60) forms of the murine receptors for tumor necrosis factor (TNF) were isolated by cross-hybridization using probes derived from the cloned human TNF receptors. Each of the murine receptors shows strong sequence homology to the corresponding human receptor (approximately 65% amino acid identity) throughout the molecule but only modest homology, limited to ligand-binding domains, between themselves. The ligand-binding characteristics of the recombinant murine receptors mirror those of the human homologs: both receptor types bind TNF-alpha and -beta with multiple affinity classes, and the ligands cross-compete. Analysis of the murine transcripts encoding these receptors revealed the presence of RNAs for one or both forms of the receptors in all cells examined. It was also demonstrated that for both types of human TNF receptor, variably sized transcripts are observed in different cells. The murine cDNAs were further used to determine the chromosomal locations of the TNF receptor genes. They are not linked, in contrast to the ligands, and map to chromosomes 4 (type 1) and 6 (type 2).

Amino Acid Sequence↗
PubMed1991

Tone-dependent responses to endothelin in the isolated perfused fetal sheep pulmonary circulation in situ.

Pulmonary vascular responses to endothelin (ET-1), a peptide derived from endothelial cells in culture, were investigated in the ovine fetus delivered by cesarean section from chloralose-anesthetized ewes with intact umbilical circulation. Circulation to the lower left lobe of the fetal lung was isolated in situ and perfused at constant flow with blood withdrawn from the inferior vena cava. Injection of graded doses of ET-1 into the left pulmonary artery decreased pulmonary arterial perfusion pressure in a dose-related manner. At doses of 100, 300, and 1,000 ng, pulmonary vascular resistance per kilogram body weight (PVR/kg) was decreased 30, 40, and 42%, respectively. However, when fetuses were ventilated with 100% oxygen, 100- and 300-ng doses of ET-1 decreased PVR/kg by 5 and 9%, respectively. In contrast, injection of 1,000 ng of ET-1 resulted in a reversal of the response, and PVR/kg was increased by 70%. Ventilation of the right lung alone resulted in a similar reversal of the vasodilator response to 1,000 ng of ET-1, and a 138% increase in PVR/kg was recorded. These studies demonstrate for the first time that ET-1 has vasodilator activity in the normally high-tone ovine fetal pulmonary circulation. In addition, these results show that ET-1 has vasoconstrictor activity in the newly ventilated low-tone pulmonary vasculature. The present data indicate the pulmonary vascular responses to ET-1 are tone dependent in the ovine fetal pulmonary circulation.

Animals↗
PubMed1991

Viscoelastic properties of transformed cells: role in tumor cell progression and metastasis formation.

The micropipette aspiration technique was used to investigate the deformation properties of a panel of nontransformed and transformed rat fibroblasts derived from the same normal cell line. In this method, a step negative pressure is applied to the cell via a micropipette and the aspiration distance into the pipette as a function of time is determined using video techniques. A standard solid viscoelastic model was then used to analyze the viscoelastic properties of the cell. From these results, it is concluded that a direct correlation exists between an increase in deformability and progression of the transformed phenotype from a nontumorigenic cell line into a tumorigenic, metastatic cell line.

Animals↗
PubMed1991

Alternative forms of the human G-CSF receptor function in growth signal transduction.

Two forms of the human granulocyte colony-stimulating factor (G-CSF) receptor (HuG-CSFR), differing only at the carboxyl terminus, were recently identified by cDNA cloning. In this report we show that transfection and subsequent expression of either cDNA clone in the interleukin-3 (IL-3)-dependent murine cell line BAF/BO3 converts the cells to G-CSF-responsiveness. The transfected cells bound HuG-CSF in a manner indistinguishable from the native receptors. Expression of a mutant form of the HuG-CSFR, with a deletion in the cytoplasmic domain, in BAF/BO3 cells failed to convert the cells to HuG-CSF-responsiveness. In a similar manner, expression of these two HuG-CSFRs in the interleukin-6 (IL-6)-dependent murine hybridoma B9 resulted in the ability of these cells to grow in HuG-CSF [corrected]. These results strongly suggest that sequences in the first 96 amino acids of the cytoplasmic domain of the HuG-CSFR are required for signal transduction in response to ligand binding.

Animals↗
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↗