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Biomedical subjects

J McCoy

Publications and source records attributed to J McCoy.

At least 19 recordsLinked to original sources
PubMed1999

Enhanced inhibition of human immunodeficiency virus type 1 by Met-stromal-derived factor 1beta correlates with down-modulation of CXCR4.

CXCR4 is a chemokine receptor used by some strains of HIV-1 as an entry coreceptor in association with cell surface CD4 on human cells. In human immunodeficiency virus type 1 (HIV-1)-infected individuals, the appearance of viral isolates with a tropism for CXCR4 (T tropic) has been correlated with late disease progression. The presumed natural ligands for CXCR4 are SDF-1alpha and SDF-1beta, which are proposed to play a role in blocking T-tropic HIV-1 cell entry. Here, we demonstrate that addition of an N-terminal methionine residue to SDF-1beta (Met-SDF-1beta) results in a dramatically enhanced functional activity compared to that of native SDF-1beta. Equivalent concentrations of Met-SDF-1beta are markedly more inhibitory for T-tropic HIV-1 replication than SDF-1beta. A comparison of the biological activities of these two forms of SDF-1beta reveals that Met-SDF-1beta induces a more pronounced intracellular calcium flux yet binds with slightly lower affinity to CXCR4 than SDF-1beta. Down-modulation of CXCR4 is similar after exposure of cells to either chemokine form for 2 h. However, after a 48-h incubation, the surface expression of CXCR4 is much lower for cells treated with Met-SDF-1beta. The enhanced blocking of T-tropic HIV-1 by Met-SDF-1beta appears to be related to prolonged CXCR4 down-modulation.

Amino Acid Sequence↗
PubMed1997

Tranquillization of cane rats (Thryonomys swinderianus) with a depot neuroleptic (pipothiazine palmitate).

Stress-induced self-trauma is a major cause of mortality among captive cane rats (Thryonomys swinderianus). Six subadult female cane rats were injected with a long-acting neuroleptic drug (pipothiazine palmitate 25 mg/kg), and an equal number were injected with isotonic saline. Their behaviour and reactions to stimuli were recorded daily. After 5 weeks, treated animals continued to display significantly less stress-related behaviour than the control group. In addition, two abbreviated studies were conducted. Eleven subadult males were treated identically to the females. Their behaviour was recorded for 1 week. Subsequently, 11 indocile animals on a commercial cane rat farm were tested for calmness, treated with pipothiazine and retested after 2.5 weeks. The results of these studies were similar to those in the female study. A significant taming effect was seen 30 days after a single treatment for all invasive or aggressive tests in treated cane rats, and no extrapyramidal effects were noted. Pipothiazine affected neither their alertness nor weight gain. However, substantial behavioural alteration requires the exposure of the animal to stressful stimuli during the treatment period. Pipothiazine palmitate decreases the stress experienced by cane rats, eases their transition to a new environment, makes them easier to handle and less likely to injure themselves.

Animals↗
PubMed1996

Genetic selection of peptide aptamers that recognize and inhibit cyclin-dependent kinase 2.

A network of interacting proteins controls the activity of cyclin-dependent kinase 2 (Cdk2) (refs 1,2) and governs the entry of higher eukaryotic cells into S phase. Analysis of this and other genetic regulatory networks would be facilitated by intracellular reagents that recognize specific targets and inhibit specific network connections. We report here the expression of a combinatorial library of constrained 20-residue peptides displayed by the active-site loop of Escherichia coli thioredoxin, and the use of a two-hybrid system to select those that bind human Cdk2. These peptide aptamers were designed to mimic the recognition function of the complementarity-determining regions of immunoglobulins. The aptamers recognized different epitopes on the Cdk2 surface with equilibrium dissociation constant in the nanomolar range; those tested inhibited Cdk2 activity. Our results show that peptide aptamers bear some analogies with monoclonal antibodies, with the advantages that they are isolated together with their coding genes, that their small size should allow their structures to be solved, and that they are designated to function inside cells.

Amino Acid Sequence↗
PubMed1994

Characterization of an RNase H deficient mutant of human immunodeficiency virus-1 reverse transcriptase having an aspartate to asparagine change at position 498.

It has been proposed that Asp-443, Glu-478, and Asp-498 are important in RNase H mediated catalysis by human immunodeficiency virus-1 reverse transcriptase (Davies J.F., Hostomska, Z. Hostomsky, Z., Jordan, S.R. and Matthews, D.A. (1991) Science 251, 88-95; Mizrahi, V., Usdin, M.T., Harington, A. and Dudding, L.R. (1990) Nucleic Acids Res. 18, 5359-5363). Single point mutations at either position 443 (Mizrahi, V., Usdin, M.T., Harington, A. and Dudding, L.R. (1990) Nucleic Acids Res. 18, 5359-5363) or 478 (Schatz, O., Cromme, F.V., Grüninger-Leitch, F. and Le Grice, S.F.J. (1989) FEBS Lett. 257, 311-314) severely inhibit RNase H activity but have only small effects on polymerase activity. We show here that a single mutation at position 498 of Asp to Asn (mutant D498N) results in a stable enzyme with a 20-fold reduction in the ratio of RNase H to polymerase activity. The mutant and wild type enzymes were equally processive, paused in the same locations, and extended primers at the same rate during DNA synthesis on a heteropolymeric RNA template. The rate of elongation on the homopolymeric template poly(rA) was also the same. The results indicate that the mutation does not affect normally measured catalytic parameters of the polymerase function of the enzyme. D498N catalyzed strand transfer synthesis on homopolymeric, but not heteropolymeric templates, indicating that RNase H activity is not required for the former activity, but is for the latter.

Asparagine↗
PubMed1993

Differential expression of tyrosine aminotransferase by glucocorticoids and insulin.

The differential response of the tyrosine aminotransferase (TAT) gene to glucocorticoids and insulin in HTC cells and cell clones derived from Reuber H35 cells (FaO and Fu5.5) have been analyzed by nuclear run-on assay. It has been previously shown that clones of cells from HTC and Reuber H35 cell lines, exhibit different sensitivities for the induction of TAT mRNA and enzyme activity. The purpose of the present study was to determine whether this difference in TAT expression between hepatocytes and hepatoma cell lines occurs at the level of TAT gene transcription or mRNA stability. A study of the TAT mRNA accumulation in all cell types showed that TAT mRNA in the Reuber H35 cell clones and hepatocytes was synthesized at a higher rate than in HTC cells. However, dexamethasone induction of alpha 1 AGP mRNA and glutamine synthetase was comparable to glucocorticoid bound receptors. In addition, cycloheximide decreased the rate at which induced levels of TAT mRNA were degraded. We also show that a heterologous fusion gene constructed from 3.0 kilobases (kb) 5' to the transcription initiation site of the rat TAT gene and the bacterial chloramphenicol acetyltransferase gene (CAT) responds similarly to dexamethasone in Fu5.5 and HTC cells as determined by transient transfection assay; and insulin inhibits dexamethasone mediated transcription in Reuber H35 cells and primary adult hepatocytes. These data indicate that DNA sequences involved in the differential response of the TAT gene to hormone treatments between HTC and Reuber H35 cell lines are not located in the first 3.0 kb fragment.

Animals↗
PubMed1993

Expression of elastin, smooth muscle alpha-actin, and c-jun as a function of the embryonic lineage of vascular smooth muscle cells.

In the avian embryo, vascular smooth muscle cells (VSMC) in the aortic arch (elastic) arteries originate in the neural crest, whereas other VSMC develop from local mesoderm. These two lineages have been shown previously to be significantly different in the timing and expression of the smooth muscle phenotype and in their respective abilities to produce an orderly elastic matrix. Two differing kinds of VSMC also have been shown in mammals. In the experimental absence of neural crest (NC) in the avian embryo, the matrix is spatially disordered. The molecular basis of the difference between the normal NC-VSMC and the surrogate mesodermal (MDM)-VSMC has not previously been investigated. In this study the expression of vascular smooth muscle alpha-actin, tropoelastin, c-fos and c-jun were examined via immunoblotting, immunohistochemistry, Northern blot, and/or transcription run-on assays. Control avian VSMC of NC origin were compared with experimental MDM-derived VSMC that populate the cardiac outflow after surgical ablation of the NC. The results show that, when they are grown under identical conditions in vitro or freshly removed from an embryonic vessel, surrogate MDM-VSMC express about 10 times more alpha-actin and tropoelastin than the normal NC-VSMC; and MDM-VSMC express up to 15 times more c-jun, whereas c-fos was not different. These results show profound heterogeneity in the regulation of VSMC-specific genes that is based in the embryonic lineage of the cells.

Actins↗
PubMed1991

Implementing a record-oriented clinical lab interface using HL7 version 2.1 at Indiana University Hospital.

At the Indiana University Hospital (IUH) site on the Indianapolis campus, HL7 version 2.1 is being implemented via a TCP/IP LAN, (using the "Minimal" Lower Layer Protocol). HL7 is currently being used to convey record-oriented lab results from the local clinical laboratory system to a clinical database system via an intelligent router, which also provides store and forward capabilities. The database application displays the lab results in a variety of configurable formats to clinical users.

Clinical Laboratory Information Systems↗
PubMed1990

Suppression of protein kinase C and the stimulation of glucocorticoid receptor synthesis by dexamethasone in human fibroblasts derived from tumor tissue.

Exposure of fibroblasts derived from keloid tissues, desmoid and dermal tissue from individuals with Gardner's syndrome (GS) to dexamethasone resulted in the suppression of protein kinase C (PKC) activity and [3H]thymidine incorporation into DNA, and a 20-fold induction of glutamine synthetase activity. Treatment of GS and keloid fibroblasts with 0.1 microM dexamethasone for 36 h increased glucocorticoid receptor (GR) synthesis, as determined by [35S]methionine labeling and immunoprecipitation with a monoclonal antibody to the human GR. The suppression of PKC activity by dexamethasone was shown to result from a loss of protein mass as determined by immunoblotting using an antibody to PKC type III. In contrast to these results, exposure of fibroblasts isolated from normal tissues to dexamethasone did not result in the suppression PKC and [3H]thymidine incorporation, there was only a sixfold induction of glutamine synthetase, and a decrease of GR synthesis. As no primary receptor binding defect could be detected, the altered response of tumor cells to steroid-occupied receptor indicates a partial post-receptor binding defect in GS and keloid cells.

Aminoisobutyric Acids↗
PubMed1987

Molecular characterization of a polymerase mutant human immunodeficiency virus.

A cell line (8E5) containing a single defective copy of human immunodeficiency virus proviral DNA and producing noninfectious viral particles lacking reverse transcriptase (RT) and endonuclease proteins has recently been described (Folks, et al., (1986b) J. Exp. Med. 164, 280-290). In this report, the mutation in a full-length molecular clone of the provirus (p8E5) was mapped to a 1931-bp region of the pol gene encoding RT. The nucleotide sequence of this segment revealed a 1-base deletion 301 codons from the common amino terminus of the 64- and 51-kDa RTs. Expression of the p8E5 RT segment in Escherichia coli generated an enzymatically inactive and truncated 33-kDa protein.

Amino Acid Sequence↗
PubMed1978

Instrumental removal of retained stones after choledochotomy.

Despite the widespread use of operative cholangiography and choledoschoscopy, stones are still left behind after exploration of the common bile duct. Reoperation is associated with a significant morbidity and mortality. The use of a steerable catheter-basket technique has enabled stones to be removed from the biliary tract in the vast majority of cases without significant complications and has practically eliminated the need for further surgery.

Adult↗
PubMed1976

Canine airway responses to acetylcholine, prostaglandin F2alpha, histamine, and serotonin after chronic antigen exposure.

Dose-response curves were obtained for aerosols of acetylcholine (ACh), prostaglandin F2alpha (PGF2alpha), histamine (H), and 5-hydroxytryptamine (5-HT) on pulmonary resistance (Rp) and dynamic lung compliance (Cdyn) in Ascaris-hypersensitive dogs. Previously, these animals had been subjected to chronic biweekly "allergic asthmatic" episodes by aerosol administration of Ascaris antigen. When examined either one week before or after antigen provocation the airways were not hyperreactive to ACh, H, or 5-HT but did demonstrate a modest hyperreactivity to PGF2alpha. When aerosol dose-response curves were obtained for these agonists immediately following an "allergic asthmatic" episode, the airways were hyporeactive to PGF2alpha, H, and 5-HT, but not to ACh. Studies with atropine indicated that the hyporeactivity was the result of decreased airway responsiveness to both direct and indirect effect of PGF2alpha and H. It is concluded that, in dogs, chronic antigen challenge is not accompanied by a general increase in airway reactivity to pharmacologic agents.

Acetylcholine↗