Biomedical subjects

R E Giles

Publications and source records attributed to R E Giles.

At least 37 records · Page 2Linked to original sources

PubMed1987

In vitro pharmacology of ICI 198,615: a novel, potent and selective peptide leukotriene antagonist.

ICI 198,615 is a representative compound from a new class of peptide leukotriene (LT) receptor antagonists. In isolated guinea pig trachea and parenchymal lung strips, ICI 198,615 demonstrated competitive antagonism of the contractile activity of LTD4 and LTE4 with pA2 values of 10.1 to 9.5, respectively. The compound also appeared to antagonize the contractile activity of LTC4 in guinea pig trachea; however, in the presence of an inhibitor of the metabolism of LTC4 to LTD4, ICI 198, 615 provided a pKB value of 5.3, indicating weak antagonism at the LTC4 receptor. ICI 198,615 was also a potent antagonist of LTC4 and LTD4 in isolated human bronchi and pulmonary veins with pKa values of 9.75 +/- 0.32 to 9.20 +/- 0.24, respectively. When evaluated for activity on a broad variety of non-LT receptors, the compound displayed a minimal selectivity of 6310 and a maximal selectivity of greater than 125,000 for the LTE4 receptor. These in vitro studies indicate that ICI 198,615 is the most potent and selective peptide LT receptor antagonist described to date.

Acetophenones↗

PubMed1987

In vivo pharmacology of ICI 198,615: a novel, potent and selective peptide leukotriene antagonist.

The in vivo pharmacology of ICI 198,615, a highly potent and selective peptide leukotriene (LT) receptor antagonist, is described. In a conscious guinea pig model, ICI 198,615 provided dose-related antagonism of aerosol LTD4-induced dyspnea when administered p.o., i.v. or by aerosol. The pharmacologic half-lives of ICI 198,615 by these routes of administration were greater than 16 hr, 68 min and 34 min, respectively. In pulmonary mechanics studies in which the effects of i.v. or aerosol administration of LTC4 and LTD4 on pulmonary resistance (Rp) or dynamic lung compliance (Cdyn) could be quantitated, ICI 198,615 provided dose-related antagonism when administered p.o., i.d, i.v. or by aerosol. The compound also antagonized LTE4-induced changes in Rp and Cdyn when administered i.v. ICI 198,615 reversed the effect of LTC4, LTD4 and LTE4 on Rp, as well as the effect of LTC4 and LTE4 on Cdyn. The compound was less able to reverse the effect of LTD4 on Cdyn. These results indicate that ICI 198,615 possesses an in vivo profile which is consonant with utility in the treatment of allergic diseases.

Aerosols↗

PubMed1987

ICI 147,798: a novel diuretic agent with beta adrenoceptor blocking activity.

ICI 147,798 is a novel compound which has both diuretic and beta adrenoceptor blocking properties in a single molecule. The natriuretic activity at 30 mg/kg p.o. was about 65% of the hydrochlorothiazide value at 10 mg/kg p.o. in saline-loaded rats; the corresponding kaliuretic activity was 42%. The natriuretic and the kaliuretic activity of ICI 147,798 in dogs were similar to that of hydrochlorothiazide over the doses 1 to 20 mg/kg p.o., although significantly less kaliuresis was obtained with ICI 147,798 at 1 mg/kg p.o. In the toad bladder preparation (analogous to the distal mammalian nephron), ICI 147,798 inhibited Na+ transport with mucosal and serosal IC50 values of 56 and 120 microM, respectively. ICI 147,798 inhibited isoproterenol-induced tachycardia in rats, cats, guinea pigs and dogs; these effects were associated with antagonism of isoproterenol vasodepressor responses. The pKB values of ICI 147,798 were 9.1 and 8.8 in isolated right atria and trachea of guinea pigs, respectively. ICI 147,798 did not exhibit local anesthetic activity in rabbit cornea and intrinsic sympathomimetic activity in catecholamine-depleted dogs and rats. Duration of beta blockade after a p.o. dose of 1 mg/kg in dogs followed the sequence: nadolol greater than ICI 147,798 greater than atenolol greater than timolol greater than propranolol. It is concluded that ICI 147,798 is a novel diuretic agent with nonselective beta blockade, and it appears to have the potential of a direct tubular action.

Adrenergic beta-Agonists↗

PubMed1986

Pharmacology of aerosol leukotriene C4- and D4-induced alteration of pulmonary mechanics in anesthetized cynomolgus monkeys.

Aerosol administration of solutions of 900 micrograms/ml of leukotriene C4 (LT) or D4 to cynomolgus monkeys produced dose-dependent, equipotent increases in pulmonary resistance (Rp) and decreases in dynamic lung compliance (Cdyn). Time to peak response was, in part, related to dose and ranged from 4 to 20 min. Both LTC4 and LTD4 were less potent than histamine. Aerosol pretreatment with the cyclooxygenase inhibitor indomethacin had no significant effect on either LTC4 or LTD4 dose-response curves; however, at the highest doses of these agonists a notable, nonsignificant inhibition of effects on both Rp and Cdyn was seen. Intravenous dl-propranolol had no effect on responses to LTD4. Aerosol pretreatment with FPL 55712 significantly (P less than 0.05) inhibited airway responses to both LTC4 and D4. In contrast, an intravenous infusion of FPL 55712 failed to block the bronchospastic activity of LTD4. In conclusion, cynomolgus monkeys are responsive to aerosol administration of LTC4 and LTD4, and the pharmacology of their responses appears to resemble that of man.

Aerosols↗

PubMed1984

Genetic studies of leucine transport in mammalian cells.

We have taken two approaches to the study of the genetics of leucine transport in mammalian cells. First, from a mutant Chinese hamster ovary cell line that has a temperature-sensitive leucyl-tRNA synthetase, we isolated temperature-resistant revertants with increased leucine transport activity. This transport elevation is reflected by increased Vmax values of leucine uptake and unchanged Km values of uptake. The temperature resistance in each revertant appears to result from the increased transport and not from any change in the leucyl-tRNA synthetase. We conclude that in each revertant there is a stable derepression of amino acid transport system L. In a second approach, we started with a Chinese hamster-human hybrid strain formed by the fusion of a temperature-sensitive leucyl-tRNA synthetase mutant hamster cell line and normal human leukocytes. From this temperature-sensitive hybrid strain we selected temperature-resistant hybrids, one class of which we found to have greatly elevated leucine transport activity. We have allowed human chromosomes to segregate from these high-transport hybrids, promoted by the presence of low concentrations of colcemid. The loss of the high-transport phenotype coincides with the loss of a single small human chromosome, which we are attempting to identify by using G-11 and G-banding staining techniques.

Amino Acyl-tRNA Synthetases↗

PubMed1983

Physiological consequences of beta-adrenoceptor desensitization in guinea pigs.

The effects of repetitive doses of beta-adrenoceptor stimulants on the resting tone and responsiveness of bronchopulmonary smooth muscle were studied in guinea pigs. Collapse time was used to assess bronchospasm in conscious animals while resistance and compliance measurements were used in the anesthetized guinea pigs. Repetitive administration of either isoproterenol or salbutamol, at effective bronchodilator doses, caused an exacerbation of the histamine-induced bronchospasm in the presence or absence of anesthesia. Repetitive administration of either prostaglandin E1, 20 micrograms/kg i.m., or aminophylline, 400 micrograms/kg i.m. did not enhance histamine-induced bronchospasm. Furthermore, in guinea pigs preselected for lack of histamine sensitivity, treatment with salbutamol caused a decrease in both dynamic compliance values and peak expiratory flow rate as well as an increase in resistance values. Trachea removed from guinea pigs treated with isoproterenol or salbutamol retained normal responsiveness to histamine and dibutyryl cAMP while the responsiveness to isoproterenol was reduced. These studies indicate that repetitive administration of beta-adrenoceptor stimulants can produce a specific desensitization of beta-adrenoceptors in pulmonary tissue and an alteration of resting baseline values of pulmonary mechanics measurements.

Albuterol↗

PubMed1983

Heterogeneity of leukotriene receptors in guinea-pig trachea.

The selective leukotriene (LT) antagonist FPL 55712 antagonized the contractile activity of synthetic LTD4 and E4 on guinea-pig trachea. Schild analysis of the antagonism provided evidence for two distinct receptors for LTD4: one with significantly higher affinity for FPL 55712 than the other. LTE4 appears to interact preferentially with the high affinity receptor.

Animals↗

PubMed1980

Assignment of a human genetic locus to chromosome 5 which corrects the heat sensitive lesion associated with reduced leucyl-tRNA synthetase activity in ts025Cl Chinese hamster cells.

A heat-sensitive (hs) leucyl-tRNA synthetase (leuRS) deficient CHO mutant, ts025Cl, was fused with human leukocytes and hybrids isolated in HAT medium at the nonpermissive temperature. Nineteen heat-resistant (hr) and 14 hs subclones were isolated from four independent primary hybrids and tested for the expression of 24 human isozymes which have been assigned to 17 human chromosomes. Four hr independent subclones and three hs independent subclones were analyzed for the presence of human chromosomes. A pattern of concordant segregation was noted for the hr phenotype, human hexosaminidase B (EC 3.2.1.30) and human chromosome 5. Based on these results, we have defined the human genetic locus which corrects the heat-sensitive lesion in ts025Cl as hr025Cl and have assigned this locus to human chromosome 5. Two hr hybrids exhibited leuRS activity 2.5 and 4 times the leuRS activity of ts025Cl but a wild-type level of activity was not restored. One hs hybrid had only 73% of the leuRS activity exhibited by ts025Cl while another hs hybrid had 1.8 times the leuRS activity of ts025Cl.

Amino Acyl-tRNA Synthetases↗

PubMed1980

Characterization of mitochondrial DNA in chloramphenicol-resistant interspecific hybrids and a cybrid.

We have examined the restriction endonuclease cleavage patterns exhibited by the mitochondrial DNAs (mtDNA) of four chloramphenicol-resistant (CAPR) human x mouse hybrids and one CAPR cybrid derived from CAPR HeLa cells and CAPS mouse RAG cells. Restriction fragments of mtDNAs were separated by electrophoresis and transferred by the Southern technique to diazobenzyloxymethyl paper. The covalently bound DNA fragments were hybridized initially with 32P-labeled complementary RNA (cRNA) prepared from human mtDNA and, after removal of the human probe, hybridized with mouse [32P]cRNA prepared from mouse mtDNA. Three hybrids which preferentially segregated human chromosomes and the cybrid exhibited mtDNA fragments indistinguishable from mouse cells. One hybrid, ROH8A, which exhibited "reverse" chromosome segregation, contained only human mtDNA. The pattern of chromosome and mtDNA segregation observed in these hybrids and the cybrid support the hypothesis that a complete set of human chromosomes must be retained if a human-mouse hybrid is to retain human mitochondrial DNA.

Animals↗

PubMed1980

Maternal inheritance of human mitochondrial DNA.

Human mitochondrial DNA was obtained from peripheral blood platelets donated by the members of several independent families. The samples were screened for nucleotide sequence polymorphisms between individuals within these families. In each family in which we were able to detect a distinctly different restriction endonuclease cleavage pattern between the parents, the progeny exhibited the maternal cleavage pattern. Informative polymorphisms were detected for Hae II (PuGCGCPy) in a three-generation family composed of 33 members, for HincII (GTPyPuAC) in a two-generation family composed of four members, and for Hae III(GGCC) in a two-generation family composed of four members. The Hae II polymorphism was analyzed through all three generations in both the maternal and paternal lines. The results of this study demonstrate that human mitochondrial DNA is maternally inherited. The techniques described for using peripheral blood platelets as a source of human mitochondrial DNA represent a convenient way to obtain data on mitochondrial DNA variation in both individuals and populations.

Blood Platelets↗

PubMed1979

X-linkage of a human genetic locus that corrects the DNA synthesis lesion in tsC1AGOH mouse cells.

GM 126 diploid fibroblasts were fused with a heat-sensitive mouse cell mutant defective in DNA synthesis, and primary hybrids were selected at permissive and nonpermissive temperatures in HAT medium. Primary hybrids, primary hybrid clones back-selected in 8-azaguanine at the permissive temperature, and subclones of heat-resistant primary hybrids isolated under nonselective conditions or after 8-azaguanine treatment were tested for heat sensitivity, the expression of 26 human enzymes assigned to 19 different human chromosomes, and the presence of human chromosomes. Only the human X chromosome and X-linked marker enzymes exhibited a clear pattern of concordant segregation with the heat-resistant phenotype. On the basis of these observations, we have defined the human genetic locus that corrects the heat-sensitive lesion in tsC1AGOH as hrC1AGOH and have assigned this locus to the X chromosome. This observation provides the first instance where two selectable markers (heat resistance and 8-azaguanine sensitivity) are found on a single human chromosome and suggests that these markers may prove to be a valuable push-pull selective system of use in determining the linear arrangement of genes on human chromosomes by somatic cell genetics.

Animals↗

PubMed1977

Somatic cell genetic assignment of the human gene for mitochondrial NADP-linked isocitrate dehydrogenase to the long arm of chromosome 15.

A double-immunodiffusion method has been developed to detect human mitochondrial NADP-linked isocitrate dehydrogenase (EC 1.1.1.42; designated as IDH-2) using rabbit antiserum against the relevant enzyme. The method allows one to distinguish human IDH-2 from its mouse counterpart in extracts from human-mouse somatic cell hybrids. A correlation was found between the expression of human IDH-2 and the presence of human chromosome 15 in a "panel" of eight independent hybrid clones. Analysis of human marker enzymes for 37 different clones revealed a syntenic relationship between IDH-2 and mannose phosphate isomerase (EC 5.3.1.8; MPI), which has been assigned to chromosome 15 (1). These results permit the assignment of the structural gene for human IDH-2 to human chromosome 15. IDH-2 and human cytoplasmic IDH (IDH-1) were found to be asyntenic. Evidence from hybrid clones carrying a human X/15 translocation chromosome indicates that the human IDH-2 gene can be localized to the q11-qter region of chromosome 15.

Animals↗

PubMed1977

Pharmacologic studies on W10,294A, a new bronchodilator.

W10,294A (1,2,3,4-tetrahydro-8,9-dimethoxy-3(2-piperidinoethyl)-5H-[1] benzopyrano [3,4-c] pyridin-5-one dihydrochloride) is a potent antagonist of the bronchoconstriction induced by histamine, methacholine or acetylcholine. In vitro evaluation on guinea pig trachea indicated that W10,294A had both direct smooth muscle relaxant activity and modest antihistaminic properties. Resistance and dynamic compliance measurements in anesthetized dogs indicated that W10,294A prevented or reversed bronchoconstriction due to histamine or pilocapine. Bronchodilator activity of long duration was observed in dogs after oral administration. W10,294A was compared with aminophylline in several tests. W10,294A was 6 times more potent than aminophylline in relaxing isolated guinea-pig trachea. In the anesthetized dog W10,294A was more potent and longer acting than aminophylline in reversing pilocarpine-induced bronchospasm. The bronchodilator activity of W10,294A was not blocked by the beta adrenoceptor antagonist bunolol. Comparative studies in dogs and guinea pigs, using identical doses, showed that W10,294A had considerably less effect on the cardiovascular system than did aminophylline.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed1976