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Biomedical subjects

R Mulligan

Publications and source records attributed to R Mulligan.

At least 19 recordsLinked to original sources
PubMed1991

Identification and regulation of the cystic fibrosis transmembrane conductance regulator-generated chloride channel.

Cystic fibrosis transmembrane conductance regulator (CFTR) generates cAMP-regulated Cl- channels; mutations in CFTR cause defective Cl- channel function in cystic fibrosis epithelia. We used the patch-clamp technique to determine the single channel properties of Cl- channels in cell expressing recombinant CFTR. In cell-attached patches, an increase in cellular cAMP reversibly activated low conductance Cl- channels. cAMP-dependent regulation is due to phosphorylation, because the catalytic subunit of cAMP-dependent protein kinase plus ATP reversibly activated the channel in excised, cell-free patches of membrane. In symmetrical Cl- solutions, the channel had a channel conductance of 10.4 +/- 0.2 (n = 7) pS and a linear current-voltage relation. The channel was more permeable to Cl- than to I- and showed no appreciable time-dependent voltage effects. These biophysical properties are consistent with macroscopic studies of Cl- channels in single cells expressing CFTR and in the apical membrane of secretory epithelia. Identification of the single channel characteristics of CFTR-generated channels allows further studies of their regulation and the mechanism of ion permeation.

Adenosine Triphosphate↗
PubMed1988

Pretreatment management of the patient receiving anticoagulant drugs.

This literature review suggests that certain low-risk dental treatment procedures can be performed in patients without altering their anticoagulant medications. Intermediate-risk dental procedures in these patients may be accomplished outside the hospital if the patient's prothrombin time value is within a specified range and if certain techniques are followed. In some cases, temporarily altering the dose of anticoagulant may be necessary. Patients receiving anticoagulant medications should continue to receive high-risk dental treatment in hospitals.

Anesthesia, Dental↗
PubMed1987

Rescue of type I collagen-deficient phenotype by retroviral-vector-mediated transfer of human pro alpha 1(I) collagen gene into Mov-13 cells.

A full-length cDNA clone corresponding to the human pro alpha 1(I) collagen gene was isolated and inserted into a retrovirus vector. Cell lines were obtained which produced recombinant viruses transducing the collagen cDNA (HUC virus). To test whether the transduced cDNA was functional, Mov-13 mouse cells were infected with the virus. These cells do not produce any type I collagen due to an insertional mutation of the pro alpha 1(I) gene which blocks transcription. While normal amounts of pro alpha 2(I) RNA were synthesized, no alpha 2(I) collagen chains were detectable in the mutant Mov-13 cells. Infection with HUC virus, however, resulted in the production of stable type I collagen, which was secreted into the medium. Analysis of pepsin-resistant proteins indicated that interspecies heterotrimers consisting of human alpha 1(I) and mouse alpha 2(I) collagen chains were secreted by the infected Mov-13 cells. Our results show that pro alpha (I) collagen chains from species as distant as human and mouse can associate to form stable type I collagen. The availability of a retrovirus vector transducing a functional pro alpha 1(I) collagen gene combined with the Mov-13 mutant system should enable us to study the effect of specific mutations on the synthesis, assembly, and function of type I collagen, not only in tissue culture but also in the animal.

Animals↗
PubMed1987

Response to anticoagulant drug withdrawal.

This study evaluated 44 separate medication withdrawal periods in 17 subjects who were attending a hospital anticoagulation clinic for management of anticoagulation medication. The data suggest that when anticoagulant withdrawal is needed for particular dental procedures, a 2-day hold is an effective period of medication withdrawal. No thromboembolic events were observed after any of the withdrawal periods. Further, no posttreatment hemorrhagic episodes were observed when the anticoagulant medication was reinstituted after dental treatment. Prothrombin time blood levels should be determined in the immediate pretreatment period, however, because the prothrombin time can fluctuate even in the best maintained patients.

Adult↗
PubMed1985

Insertion of the bacterial gpt gene into the germ line of mice by retroviral infection.

Mouse substrains genetically transmitting the exogenous Moloney murine leukemia virus (Mo-MuLV) at a single locus have been derived previously by infection of preimplantation embryos. Here we explore the potential of retroviral vectors for transferring nonviral genes into the germ line of mice. Preimplantation mouse embryos were cocultivated with a cell line that produces a recombinant retrovirus whose genome carries the Escherichia coli gene gpt. We show that the vector sequence was inserted into the genome of the embryo and into the germ line at a frequency similar to that for the Mo-MuLV-helper sequence. A new mouse strain, Mgpt-1, was developed that is homozygous for a single MSVgpt proviral genome. The proviral sequences were highly methylated and not expressed in tissues of Mgpt-1 mice. When cells derived from transgeneic animals were treated with 5-azacytidine, the proviral sequences were not methylated and were transcriptionally activated. These results indicate that nonviral genes that are under the control of the viral long terminal repeat are inactivated when transferred into the germ line of animals.

Animals↗