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S D Gardner

Publications and source records attributed to S D Gardner.

At least 19 recordsLinked to original sources
PubMed1997

Purification and characterization of sn-1-stearoyl-2-arachidonoylglycerol kinase from pig testes.

1-Stearoyl-2-arachidonoylglycerol (SAG) kinase was identified in the particulate fraction of pig testes. This activity was enriched by hydroxyapatite and blue dye chromatography. The enzyme was selective for polyunsaturated diradylglycerol species and activity was not modulated by other diradylglycerol species or sphingomyelin metabolites. Further purification resulted in the isolation of 55 and 50 kDa proteins that corresponded with SAG kinase activity. These results support the view that the phosphorylation of polyunsaturated diradylglycerol is regulated by structural determinants in the molecule.

Animals↗
PubMed1997

The antigen receptors on mature and immature T lymphocytes are coupled to phosphatidylcholine-specific phospholipase D activation.

Phosphatidylcholine-phospholipase D has been proposed to play a key role in the transduction of the proliferative responses of a wide range of mitogens and growth factors. We now report that the antigen receptors on T lymphocytes derived from human tonsillar or murine splenic preparations are coupled to phosphatidylcholine (PtdCho)-phospholipase D (PLD) activation following stimulation of these T cells with anti-CD3 antibodies. However, since we also demonstrate that the antigen receptors on murine thymocytes are coupled to PtdCho-PLD activation, we propose that it is unlikely that this PLD pathway plays a central role in the transduction of T-cell proliferative responses, but rather, may be involved in either driving cells into cycle or maintaining cell cycle progression, processes required both for proliferation and activation-induced cell death. Whilst the molecular mechanisms underlying T-cell receptor (TCR)-coupling to PtdCho-PLD activation in these cells have not been fully defined, kinetics studies and experiments using pharmacological inhibitors of protein tyrosine phosphatases (PTPases) and reconstituting CD3-coupled PtdCho-PLD activity in streptolysin-O permeabilized cells, suggest that the TCR/CD3 complex, under optimal conditions of activation, may be predominantly coupled to PtdCho-PLD activation downstream of tyrosine phosphorylation of phospholipase C-gamma (PLC-gamma), phosphatidylinositol (PtdIns)P2 hydrolysis, calcium mobilization and protein kinase C (PKC) activation.

Animals↗
PubMed1991

Preparation of monoclonal antibodies to JC virus and their use in the diagnosis of progressive multifocal leucoencephalopathy.

Seven monoclonal antibodies (MAbs) to polyomavirus JC were produced, and one was selected for use in immunofluorescence (IF) tests on brain material from patients with suspected progressive multifocal leucoencephalopathy (PML). The selected MAb (5.12.2) reacted by IF with JC-infected primary human foetal glial (PHFG) cell cultures (titre 1/200,000) but not with BK-infected human embryo lung (HEL) fibroblasts (titre less than 1/20). Its haemagglutination-inhibition (HI) titre was high (greater than 1/5 x 10(6)) against JC virus but low (less than 1/5) against BK virus. A diagnosis of PML was confirmed on brain biopsy or at postmortem in four patients, two of whom were also infected with human immunodeficiency virus (HIV). In one of the patients, specific detection of JC virus antigen had not been possible using our routine high titred JC and BK human sera due to interference by JC antibody present in the cerebrospinal fluid (CSF). Viral antigen was, however, detected with the MAb 5.12.2.

Adult↗
PubMed1990

Regulation of bombesin-stimulated inositol 1,4,5-trisphosphate generation in Swiss 3T3 fibroblasts by a guanine-nucleotide-binding protein.

The stimulation of inositol phosphate generation by bombesin and GTP analogues was studied in Swiss 3T3 cells permeabilized by electroporation. Bombesin-stimulated inositol phosphate generation is potentiated by guanosine 5'-[gamma-thio]triphosphate (GTP[S]) and inhibited by guanosine 5'-[beta-thio]diphosphate at all peptide concentrations tested, with no change in the EC50 value (concn. giving half-maximal response) for the agonist. Kinetic analysis showed that, although bombesin-stimulated [3H]InsP3 generation in [3H]inositol-labelled cells was rapid (maximal by 5-10 s), the response to GTP[S] alone displayed a distinct lag time of 20-30 s. This lag time was significantly decreased by the addition of bombesin, suggesting that in this system agonist-stimulated GTP/GDP exchange occurs. In addition, bombesin-stimulated generation of Ins(1,4,5)P3 mass at 10 s was enhanced by GTP[S] in the absence of a nucleotide response alone, a result consistent with this proposal. Pretreatment of the cells with phorbol 12-myristate 13-acetate (PMA) resulted in a dose-dependent inhibition of bombesin-, but not GTP[S]-, stimulated inositol phosphate generation. Furthermore, although PMA pretreatment did not affect the lag time for InsP3 formation in response to GTP[S] alone, the degree of synergy between bombesin and the nucleotide was severely decreased at early time points. The results therefore demonstrate that the high-affinity bombesin receptor is coupled via a G-protein to phospholipase C in a manner consistent with a general model for receptor-G-protein interactions and that this coupling is sensitive to phosphorylation by protein kinase C.

Animals↗
PubMed1990

Human papillomavirus types in anogenital warts of children.

Tissue from anogenital warts of 25 children, 10 of whom were suspected of being victims of sexual abuse, was investigated by dot blot and Southern blot techniques for human papillomavirus (HPV) types. HPV DNA was detected in 22 children, two of whom had double infections. The genital HPV types 6 and/or 11 were detected in 20 children, and in three children other HPV types were found. One had HPV 18 (as well as 11); in a second child a possible skin type, HPV 2, was detected; and the third child was infected with an unidentified type. In three cases genital wart material was available from one of the parents, and in all three the HPV type was the same as that of the child. For nine other children one or both parents were reported to have genital warts. The source of infection appeared to be the adult genital tract, but sexual contact might not be the only means of transmission.

Anus Neoplasms↗
PubMed1990

Progressive multifocal leukoencephalopathy-remission with cytarabine.

A 51-year-old woman who was in complete remission from non-Hodgkin's lymphoma, developed a rapidly progressive dementia. Progressive multifocal leukoencephalopathy (PML) was diagnosed on the basis of a rising antibody titre to JC polyomavirus in cerebro-spinal fluid and serum and the presence of diffuse white matter changes on magnetic resonance imaging. She was treated initially with intravenous cytarabine and showed minimal improvement. Rapid improvement occurred when intrathecal cytarabine was added and the patient is in complete remission from both lymphoma and PML 20 months later.

Cytarabine↗
PubMed1989

The effect of cholera toxin on the inhibition of vasopressin-stimulated inositol phospholipid hydrolysis is a cyclic AMP-mediated event at the level of receptor binding.

Incubation of L6 skeletal myoblasts for 16 h with cholera toxin but not with pertussis toxin, led to the inhibition of inositol phosphate generation induced by subsequent exposure to vasopressin. The effects of the toxin on inositol lipid metabolism were accompanied by the total ADP-ribosylation of the available cholera-toxin substrates within the cells. Immunological analysis demonstrated that the two polypeptides modified in vivo by cholera toxin were different forms of Gs alpha (alpha subunit of Gs). No novel cholera-toxin substrate(s) were detected. The cholera-toxin-mediated inhibition of vasopressin-stimulated inositol phosphate generation could be mimicked by both forskolin and dibutyryl cyclic AMP, but not by the separated subunits of the toxin. Receptor-binding studies demonstrated that the inhibition of agonist-stimulated inositol phosphate generation was accompanied by a decrease in cell-surface vasopressin-binding sites, with no effect on the affinity of these for the hormone. We suggest that the effect of cholera toxin and agents which increase intracellular cyclic AMP on vasopressin-stimulated inositol lipid hydrolysis is an effect on receptor number, and that there is no requirement to postulate a role for a novel G-protein, which is a substrate for cholera toxin, in the regulation of inositol phospholipid metabolism.

Adenosine Diphosphate↗
PubMed1989

Serological typing scheme for BK-like isolates of human polyomavirus.

Human polyomavirus BK-like isolates were subjected to restriction endonuclease analysis with the enzymes EcoRI and Hind III. End-point dilution was used to obtain homogeneous virus pools for DNA analysis and to remove JC virus from a mixed stock. The results of Hind III digestion suggested that two subgroups could be distinguished. Several BK-like isolates were purified and rabbit antisera raised. The isolates were compared with each other and with BK and JC viruses by haemagglutination-inhibition (HI) and by neutralisation. JC virus was serologically distinct, but all the other isolates showed some cross-reactivity. Two subgroups were again evident: GS and PG were with prototype BK in subgroup 1, and MG and IV were in subgroup 2. Two isolates, AS and SB, reacted with isolates of both subgroups 1 and 2 but were distinct from one another: their genome was similar to subgroup 1 isolates. Typing by HI or by neutralisation may form a basis for grouping BK-like polyomavirus isolates.

Adolescent↗
PubMed1989

Characterization of a new polyomavirus (Polyomavirus papionis-2) isolated from baboon kidney cell cultures.

Viruses with papovavirus morphology were seen in fluids from baboon kidney cell cultures on three separate occasions (isolates A, B, and C). The size of the virions, 47.9 nm, placed the virus in the polyomavirus genus. It grew well in baboon kidney and Vero cells and less well in human embryo lung (HEL) fibroblasts. The virus could not be identified as the previously described baboon polyomavirus, SA 12, or as any of the other known primate polyomaviruses BK, JC or SV 40, the non-primate viruses mouse polyoma, K, rabbit kidney vacuolating virus (RKV) or bovine polyomavirus (FRKV) by immunofluorescence, immune electron microscopy or hemagglutination inhibition (HI) tests. A rabbit antiserum to the new virus (isolate A) reacted only with the three isolates and not with the other primate polyomaviruses studied. Thirteen percent of 118 wild-caught baboons (Papio anubis) had HI antibody to the new polyomavirus and 21 percent were seropositive for SA 12; only two baboons had antibody to both viruses. These results suggest that in baboons there are two antigenically distinct polyomaviruses which circulate independently. The two viruses may also be distinguished by their hemagglutinating properties: SA 12 agglutinated erythrocytes from a wider range of species but only the newly recognized polyomavirus agglutinated baboon erythrocytes. We propose that the two baboon viruses, SA 12 and the new virus, should be named Polyomavirus papionis-1 and Polyomavirus papionis-2 respectively.

Animals↗
PubMed1989

An indirect immunofluorescence method for detection of infectious BK virus in urine.

An indirect immunofluorescence (IF) method is described for the detection of infectious BK virus in urine within seven days in contrast to up to three months or longer using routine tissue culture. Virus is pelleted from the urine, inoculated onto pre-formed monolayers of human embryo lung (HEL) fibroblasts, and infected cells are detected in an indirect fluorescent antibody test using a human serum. The sensitivity of the IF method is 91%. Positive isolates may be confirmed as BK virus using specific rabbit antisera on the original inoculated cultures. Furthermore, a virus stock may be grown up by passage from the original culture fluids for further studies such as DNA analysis. As a broadly-reactive human serum is used for screening the cultures, other viruses which grow in HEL cells, such as CMV, may also be detected.

BK Virus↗
PubMed1989

Nucleotide sequence of the human polyomavirus AS virus, an antigenic variant of BK virus.

The complete DNA sequence of the human polyomavirus AS virus (ASV) is presented. Although ASV can be differentiated antigenically from the other human polyomaviruses (BK and JC viruses), it shares 94.9% homology at the nucleotide level with the Dunlop strain of BK virus. Differences found in ASV relative to BK virus include the absence of tandem repeats in its regulatory region, the deletion of 32 nucleotides in the late mRNA leader region (altering the initiation codon for the agnoprotein), the presence of a cluster of base pair substitutions within the coding region of the major capsid protein, VP1, and the absence of 4 amino acids in the carboxy-terminal region of the early protein, T antigen. The 43 nucleotides deleted in the Dunlop strain of BK virus relative to the Gardner prototype strain of BK virus are present in ASV. Possible reasons for the distinct antigenicity of the ASV capsid, given the high degree of nucleotide homology with BK virus, are discussed. To reflect the high degree of sequence homology between ASV and BK virus, we suggest ASV be renamed BKV(AS).

Antigens, Viral↗
PubMed1988

Progressive multifocal leucoencephalopathy and viral antibody titres.

Progressive multifocal leucoencephalopathy (PML) is caused by a papovavirus but serum antibody titres are generally considered unhelpful in clinical diagnosis because antibodies to the commonest causal agent (JC virus) are frequently found in normal adults. There is little published information about CSF titres but usually they have not been useful. Two cases of PML, confirmed by autopsy, are described where CSF antibody to JC virus was measured. In one case the JC antibody titre was significantly higher in the CSF than the serum and we suggest that this finding is diagnostically useful. In this case there was a transient stabilization of the disease following treatment with cytarabine with a change in antibody titres suggestive of reduced viral replication in the central nervous system and a host response to the infection. In the other case, which was untreated, rising serum antibody levels indicated active infection with a host response.

Adult↗