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Biomedical subjects

M J Hughes

Publications and source records attributed to M J Hughes.

At least 19 recordsLinked to original sources
PubMed1992

ATP-citrate lyase as a target for hypolipidemic intervention. Sulfoximine and 3-hydroxy-beta-lactam containing analogues of citric acid as potential tight-binding inhibitors.

Citric acid analogues (+/-)-12a,b and (+/-)-17a,b, where one of the primary carboxylates has been replaced by a sulfoximinoyl and a 3-(3-hydroxy-beta-lactamyl) moiety, respectively, have been synthesized and evaluated as inhibitors of ATP-citrate lyase. The design of these inhibitors was based on methionine sulfoximine and tabtoxinine beta-lactam, potent, tight-binding inhibitors of glutamine synthetase. Both ATP-citrate lyase and glutamine synthetase employ phosphate-carboxylate anhydrides as a method for carboxylate activation during catalysis. Only one diastereomer, (+/-)-12a, displayed weak, reversible inhibition, while the remaining citrate analogues (+/-)-12b and (+/-)-17a,b were inactive against the lyase. No time-dependent inactivation of the enzyme was observed.

ATP Citrate (pro-S)-Lyase↗
PubMed1992

The purification of a human mismatch-binding protein and identification of its associated ATPase and helicase activities.

A mismatch-binding protein has been purified an estimated 4500-fold from HeLa nuclear extracts using four different chromatographic steps. Two polypeptides of apparent molecular weight of 160,000 and 100,000 were present in the final affinity-purified fraction as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Partial proteolytic clipping of the protein-DNA complexes visualized after UV treatment indicated that the 100-kDa polypeptide is most likely a degradation product of the 160-kDa polypeptide. UV cross-linking experiments have shown that both these polypeptides bind specifically to oligonucleotide duplexes containing G/T mismatches. Direct DNA binding studies and band-shift competition assays showed that although the mismatch-binding protein binds with highest affinity to oligonucleotides containing G/T mismatches, it is also capable of binding to oligonucleotides containing other mispairs. The purified protein has an associated Mg(2+)-dependent ATPase activity, which is markedly enhanced in the presence of single-stranded DNA. A helicase capable of unwinding a 34-mer oligonucleotide, annealed to a complementary sequence in single-stranded M13, also copurified with the mismatch-binding protein. This reaction occurs in an ATP- and magnesium-dependent manner.

Adenosine Triphosphatases↗
PubMed1992

A comparison of HIV-1, HBV, and HTLV-I/II seroprevalence rates of injured patients admitted through California emergency departments.

STUDY OBJECTIVE: To determine the seroprevalence rates of hepatitis B virus (HBV) and human T-lymphotropic virus (HTLV-I/II) and to compare these rates with the HIV-1 seroprevalence rate in a sample of injured patients admitted through ten California emergency departments. DESIGN: Prospective blinded testing for serologic markers for HBV, HTLV-I/II, and HIV-1 on routinely collected blood samples. SETTING: Ten California hospitals were chosen to reflect geographic and demographic diversity. TYPE OF PARTICIPANTS: All injured adult patients who were admitted to a participating hospital through the ED during consecutive three-month periods from June through November 1989. MEASUREMENTS: Serum samples were tested for HIV-1 antibody, HTLV-I/II antibody, and hepatitis B surface antigen (HBsAg) using standard methods. Mann-Whitney U tests, chi 2 tests for independence, sign tests, chi 2 tests for goodness of fit, and logistic regression were used as appropriate. RESULTS: Seroprevalence rates were as follows: HBV, 2.6% (57 of 2,209); HTLV-I/II, 2.0% (46 of 2,262); and HIV-1, 1.4% (31 of 2,264). CONCLUSION: The seroprevalence rate of HBV was slightly higher than that of HIV-1 in this sample of injured patients. Mortality estimates suggest, however, that HBV and HIV-1 pose roughly similar risks to emergency personnel, although the risk of HBV infection can be markedly reduced by vaccination. The data from this and other studies suggest that the ED incidence of HTLV-I/II in United States is low. The relative health risks to emergency personnel from HTLV-I/II appear to be minimal at this time.

California↗
PubMed1992

Drug interactions represented by high resolution computer graphics.

The amount of backward walking induced in mice by co-administration of clenbuterol, a beta-adrenoceptor agonist and putative antidepressant, and the benzodiazepine chlordiazepoxide was plotted as a three-dimensional surface, using modified Uniras software. The surface was compared with the theoretical surface to be expected if the interactions between the two drugs were merely additive. The difference between the theoretical and the obtained surfaces was plotted and a functional representation of statistical variability was 'draped' over the difference model. The computer methods can be applied to small amounts of irregularly distributed data, and results are apparent from simple inspection, e.g. the highest peak of backward walking is also the most reliable statistically. The technique is useful for both laboratory and clinical studies.

Animals↗
PubMed1992

Pregnancy diagnosis by biochemical assay.

If pregnancy diagnosis by biochemical assay is to become practical, new marker characterization will be required. Pregnancy marker development is reviewed in dogs and other species, as are molecular biology techniques that have the potential to reveal previously inaccessible targets in the dog.

Animals↗
PubMed1991

A rapid screening test for HIV-1 antibodies: application to biological studies on human tissue.

Human umbilical cord vessels are commonly used as a source of human vascular tissue for physiological studies and as a source of endothelial and smooth muscle cells. Blood samples from 236 umbilical cords were tested for the presence of HIV-1 antibodies to access the prevalence of HIV-1 infection and to evaluate possible methods for screening umbilical cords. Ten of the 236 samples were HIV-1 antibody positive by ELISA whereas 3 were positive by Western blot and a new method, the Quick-Western blot. Two of the 3 positive samples contained antibody bands against gp160, gp120, gp41, and p24 HIV-1 proteins, and one sample had antibodies against only gp160, gp120 and gp41. The Quick-Western blot required only 45 minutes for the analysis while the ELISA and Western blot took 3 hours and 18 hours, respectively. These data indicate that HIV-1 infection in mothers may present a hazard to researchers using human umbilical cords as a source of vascular tissue. The Quick-Western blot method is a simple, portable, rapid and accurate method that may be used to screen blood. The short analysis time of the Quick-Western blot allows the identification of infected blood before the tissue deteriorates as a source of cells or vascular tissue for experimental studies.

Acquired Immunodeficiency Syndrome↗
PubMed1991

The HIV-1 seroprevalence rate of injured patients admitted through California emergency departments. California HIV-1 Emergency Department Seroprevalence Study Group.

STUDY OBJECTIVES: To measure the HIV seroprevalence of injured emergency department patients in a number of California hospitals and to examine the relationship between ED seroprevalence and local AIDS incidence. DESIGN: Prospective blinded testing for HIV-1 antibody was performed on routinely collected blood samples. SETTING: Ten California hospitals; group 1 included three hospitals from counties of high AIDS incidence (more than 40 cases per 100,000 population), group 2 included three hospitals from counties of intermediate AIDS incidence (20 to 40 cases per 100,000 population); and group 3 included four hospitals from counties of low AIDS incidence (less than 20 cases per 100,000 population). TYPE OF PARTICIPANTS: Eligible patients were all adult trauma victims admitted to a participating hospital through the ED during a consecutive three-month period occurring between June and November 1989. MEASUREMENTS: HIV-1 antibody testing was done using enzyme immunoassay confirmed by immunofluorescence assay. Equivocal results were confirmed by Western blot. Mann-Whitney U test, chi 2 test, and multiple logistic regression were used where appropriate. RESULTS: There were 2,264 patients with adequate blood samples for serologic testing. The seroprevalence rates for hospitals in groups 1, 2, and 3 were significantly different (chi 2 = 8.44, P = .02): Group 1, 2.5% (19 of 756: 95% confidence interval [CI], 1.5% to 3.9%); group 2, 0.9% (10 of 1,078; CI, 0.5% to 1.7%); and group 3, 0.5% (two of 430; CI, 0.06% to 1.7%). CONCLUSION: This study suggests that local AIDS incidence rates do not necessarily predict the seroprevalence rates of injured patients who are admitted through local EDs.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Mapping and interpreting complex interactions between psychoactive drugs by simple computer-generated models.

Drug combinations often yield results not readily predictable from those of their separate constituents. Computer programs have been developed to generate models of dual drug effects to analyse the results of experiments involving drug combinations. Single and combined dose-response results of rat locomotor activity are expressed as three-dimensional models. A manually plotted isobol diagram, showing eqi-active dose combinations of amylobarbitone and dexamphetamine, is compared with isobols constructed by the computer. A simple dose model theory is proposed which assumes that the two drugs have merely additive effects; differences between expectations from this theoretical model and the experimental results actually obtained were found by the computer. This computer approach allows detailed analysis of results. Three-dimensional dose response surfaces can provide a simple visual guide to dose combinations whose effects deviate significantly from those expected if the constituents were simply additive. Areas of special interest can thus be highlighted.

Animals↗
PubMed1990

HIV antibody seroprevalence among prisoners entering the California correctional system.

A cross-sectional blind study was conducted in the spring of 1988 to estimate the extent of human immunodeficiency virus (HIV) infection among inmates entering the California correctional system. Of the 6,834 inmates receiving entrance physical examinations during the study period, 6,179 (90.4%) had serum tested for the presence of HIV antibodies after routine blood work was completed and personal identifiers were removed. Seroprevalence was 2.5% (95% confidence interval, 2.1% to 3.0%) among the 5,372 men tested and 3.1% (95% confidence interval, 2.1% to 4.5%) among the 807 women tested. Seroprevalence was more than twice as high among men arrested in the San Francisco Bay Area as in those arrested elsewhere in the state. The regional differences in HIV seroprevalence observed among entering inmates mirror infection rates reported among intravenous drug users from the same regions.

California↗
PubMed1989

Purification and characterization of a protein from HeLa cells that binds with high affinity to the estrogen response element, GGTCAGCGTGACC.

A non-histone protein, NHP1, that binds with high affinity to the estrogen response element (ERE), GGTCAGCGTGACC, has been purified approximately 45,000-fold from HeLa cells by a combination of chromatography on Sephacryl S-300, heparin-Sepharose, Mono Q (FPLC), and sequence-specific oligonucleotide-Sepharose. The native protein has a molecular weight of 170,000 and is composed of two polypeptides of 85 and 75 kDa. The two polypeptides are different as judged by peptide mapping, and only the 85-kDa polypeptide can be cross-linked to the bromodeoxyuridine-substituted synthetic ERE by UV irradiation. The native protein binds to the ERE with an apparent KD of 1 x 10(-11) M and has a pI of 5. The contact points of the protein with individual bases of the ERE have been determined by using partially depurinated and depyrimidinated synthetic oligonucleotides. The strongest contact points of NHP1 with the ERE are 5'AGCG3' in the center of the palindrome and differ from those of the estrogen receptor. NHP1 appears to produce specific nicks around the central CpGs of the ERE, thereby suggesting that it may play a role in active demethylation of mCpGs.

Base Sequence↗
PubMed1989

The ubiquitous nuclear protein, NHP1, binds with high affinity to different sequences of the chicken vitellogenin II gene.

In gel shift assays, affinity chromatography-purified NHP1 forms a stable complex with different sequences of the chicken vitellogenin II gene. The apparent KD of NHP1 with the estrogen response element (ERE) containing 5-methylcytosine is 1 X 10(-11) M. NHP1 does not form a complex with the Xenopus vitellogenin ERE where the GCG bases are replaced by CAG. NHP1 is closely related if not identical to the other ubiquitous proteins NHP2, NHP3 and NHP4 that bind specifically to different sequences. All four proteins behave identically on chromatography and give identical patterns in proteolytic bandshift assays. NHP1, NHP2 and NHP3 have a native molecular weight of 170,000 and are composed of two polypeptides of 85 and 75 kDa. The possible function of NHP1 is discussed.

Animals↗
PubMed1988

Histamine stimulation of prostaglandin and HETE synthesis in human endothelial cells.

Endothelial cells (EC) cultured from human umbilical artery (UA) and vein (UV) metabolized [14C]arachidonic acid to prostaglandins (PGs), monohydroxyeicosatetraenoic acids (HETEs), and epoxyeicosatrienoic acids (EETs). Major radioactive products were identified as 6-keto-PGF1 alpha, PGE2, PGF2 alpha, 12-hydroxy heptadecatrienoic acid, 15-HETE, and 11-HETE. In addition, extracts from UV ECs contained 12-HETE, 5-HETE, 14,15-EET, and 5,6-EET as minor products, whereas extracts from UA ECs contained only 12-HETE as a minor product. UA ECs also produced metabolites comigrating with 14,15-EET, 11,12-EET, 8,9-EET, and 5,6-EET. Histamine increased the release of [14C]PGs and [14C]HETEs from [14C]arachidonic acid-labeled ECs. Indomethacin, aspirin, and nordihydroguauretic acid completely inhibited synthesis of both [14C]PGs and [14C]HETEs from exogenous [14C]arachidonic acid in these cells. Microsomes metabolized [14C]arachidonic acid to the same [14C]PGs and [14C]HETEs as intact cells. Pretreatment of microsomes with indomethacin completely inhibited formation of these products. These data indicate that UA ECs and UV ECs metabolize endogenous and exogenous arachidonic acid to both PGs and HETEs. Also 15-HETE and 11-HETE appear to be synthesized by a microsomal enzyme with the properties of cyclooxygenase.

Arachidonic Acids↗
PubMed1986

Antagonistic activity of tiotidine and ranitidine on guinea-pig and rabbit atria.

Isolated, spontaneously beating atrial pairs from rabbits and guinea-pigs were used to determine and to compare the activity of ranitidine and tiotidine as antagonists of histamine stimulated chronotropic activity. Ranitidine produced a classical competitive, reversible antagonism of histamine effects with a pA2 in rabbit atria of 8.2. In contrast, tiotidine produced both a dextral shift of the log dose-response curve, as well as a previously unreported suppression in the maximal response produced by histamine. In accordance with receptor theory, this type of activity represents a dualistic antagonism of histamine chronotropic responses.

Animals↗
PubMed1986

Effect of in vivo antiestrogen pretreatment on rabbit atrial chronotropic response to histamine.

The chronotropic response (delta rate) to histamine (1.4 to 18 X 10(-6) M) of isolated atria from antiestrogen (tamoxifen)-pretreated immature female rabbit was investigated. Tamoxifen treatment (1.0 and 10.0 mg/kg/day for 14 days) had no significant effect on the delta rate. The Rmax and D1/2max were not significantly different in the two tamoxifen-treated groups compared to the oil-treated (1.0 ml/kg/day for 14 days) control group. Cimetidine (2.8 X 10(-7) M) inhibited the delta rate to histamine in all groups: control, 27%; tamoxifen (1.0 mg/kg), 38%; and tamoxifen (10.0 mg/kg), 28%. Only the low dose of tamoxifen was found to be estrogenic (uterotropic). We conclude that tamoxifen pretreatment, both at estrogen-agonist and estrogen-antagonist doses, is without effect on atrial chronotropic response to histamine.

Animals↗
PubMed1986

Traumatic rupture of right mainstem bronchus in a child.

We report a case of a 7-year-old boy who sustained a ruptured right mainstem bronchus in a motor vehicle accident. The clinical presentation, pathophysiology, and diagnosis of tracheobronchial injuries secondary to nonpenetrating thoracic trauma are discussed.

Accidents, Traffic↗