Search PubMed⌕ Search

Biomedical subjects

G Smith

Publications and source records attributed to G Smith.

At least 757 records · Page 42Linked to original sources
PubMed1984

Ergonovine-induced myocardial ischemia: no role for serotonergic receptors?

Because ergonovine appears to produce coronary contractions by a serotonergic (5-HT) mechanism, we attempted to prevent ergonovine-induced ischemia in patients with vasospastic angina by pretreatment with ketanserin, a new selective 5-HT blocker. We studied seven patients with consistently positive results of ergonovine testing (ST segment elevation in three and ST segment depression in four). Ergonovine testing was performed before and after a bolus of 10 mg of ketanserin (all patients) and infusion of 2 to 4 mg/hr for 8 hr (six patients). To assess 5-HT blockade during ketanserin infusion, the constrictor response of hand veins to 5-HT was tested before and after ketanserin. Despite evidence of 5-HT blockade in hand veins, ergonovine-induced ischemia was not prevented by ketanserin in any patient, and there was no significant change in the dose of ergonovine required to provoke ischemia. In one patient, four spontaneous episodes of ST segment elevation occurred during infusion of ketanserin. The plasma concentrations of ketanserin at the time of ergonovine testing ranged from 61 to 127 ng/ml (mean 102) and were well above those that completely inhibit canine coronary 5-HT contractions in vitro. Although human coronary arteries may differ in their responsiveness to 5-HT or ketanserin, these data suggest that ischemia from ergonovine-induced coronary vasospasm is not mediated by 5-HT receptors.

Aged↗
PubMed1984

Whole blood and red cell ATP content in patients with peripheral vascular disease: the effect of cigarette smoking and oxpentifylline.

The relationship between erythrocyte ATP content and the presence of atherosclerotic peripheral occlusive vascular disease was investigated. In 20 elderly patients with severe peripheral vascular insufficiency (10 male, 10 female; age 68.8 +/- 12.5 years; Mean +/- SD) the mean erythrocyte ATP content was 1.57 +/- 0.16 mmol/litre. In a sex and age matched group (69.1 +/- 9.6 years) with no signs or symptoms of peripheral or myocardial ischaemia, erythrocyte ATP content did not differ significantly (1.49 +/- 0.29 mmol/litre). In young healthy volunteers, there was no difference in erythrocyte ATP content between males and females or between cigarette smokers and non-smokers, nor were the values for the young group different from those obtained from the elderly patients. The effect of oxpentifylline administration on erythrocyte ATP levels in patients with peripheral vascular disease was also studied. Administration of oxpentifylline (1.6 g per day in divided doses) over 7 days had no effect on erythrocyte ATP content in 10 patients (5 male, 5 female) with ischaemic lower limbs. These results suggest that measurement of erythrocyte ATP content is unlikely to be a useful index in the assessment of peripheral vascular disease.

Adenosine Triphosphate↗
PubMed1984

Comparison of the effects of pancuronium and atracurium on the lower esophageal sphincter.

The effects of pancuronium and atracurium on the lower esophageal sphincter pressure (LESP) were studied in 24 healthy patients anesthetized with 0.5% halothane in 66% nitrous oxide in oxygen. After pancuronium (0.1 mg X kg-1) given intravenously there was a significant increase in LESP from a control value of 36 +/- 4.0 cm H2O to 50 +/- 4.6 cm H2O at 1 min. This produced an increase in barrier pressure (BRP) from 26 +/- 3.7 cm H2O to 41 +/- 4.3 cm H2O. These changes were sustained for 5 min accompanied by a significant increase in arterial pressure and heart rate. Atracurium (0.6 mg X kg-1) had no cardiovascular effects and produced little changes in either LESP or BRP. The findings of this study suggest that pancuronium may be of benefit in a rapid sequence induction.

Anesthesia↗
PubMed1984

Rational-emotive therapy and the reduction of interpersonal anxiety in junior high school students.

This study evaluated the effectiveness of rational-emotive therapy and rational-emotive imagery. Fifty-nine junior high school students who volunteered to participate in treatment for interpersonal anxiety were randomly assigned to rational-emotive therapy without imagery (RET), rational-emotive therapy with imagery (REI), relationship-oriented counseling (ROC), and waiting-list control (WLC) groups. Groups met for seven 50-minute treatment sessions during a three-week period. Assessments were conducted at pretreatment, posttreatment, and three-week follow-up. Both self-report and sociometric measures were used to evaluate treatment outcome. At postassessment, both the RET and REI groups were rated on sociometric measures as significantly less interpersonally anxious than the WLC group. Mean scores favored the RET and REI groups, but no significant differences between these groups and the ROC group were obtained. The self-report measure did not significantly differentiate between groups, but the REI group demonstrated significant pre- to follow-up changes. Both the RET and REI groups yielded greater reductions in irrational thinking than did the ROC and WLC groups. In addition, the pattern of the results supported the use of rational-emotive imagery as a component of rational-emotive therapy. The practical implications of these findings are discussed.

Adolescent↗
PubMed1984

Systemic lupus erythematosus in the elderly: clinical and serological characteristics.

Thirteen patients (all women) who developed systemic lupus erythematosus (SLE) after the age of 55 are reported. They constitute 18% of 71 consecutive SLE patients followed prospectively. Presenting features were predominantly cutaneous, neuropsychiatric and pulmonary. They had more interstitial lung disease and less arthritis than the younger patients. Eleven had positive antinuclear antibodies and only 4 had antibody to DNA. Strikingly, 12 had antibody to Ro(SSA) (accompanied by anti-La(SSB) in 8) compared to 36% in the younger group. SLE should be considered in older patients. Lung involvement is prominent. Antibodies to Ro and La are frequent and are a useful aid in diagnosis.

Aged↗
PubMed1984

Cytotoxic cell populations in normal and alloimmunized pregnant mice.

Cytotoxic cell activity directed against paternal alloantigens was investigated in primiparous C57BL/10 and CBA/Ca mice using a microcytotoxicity assay. Most allogeneically or syngeneically mated females lacked effector cells in their spleens or paraaortic lymph nodes both during pregnancy and immediately postpartum. However, spleen, cells from 33% of C57BL/10 females mated to CBA/Ca males exhibited low levels of paternal target cell killing (P less than 0.05-0.01). Alloimmunization of virgin mice prior to mating resulted in only allogeneically mated females producing cytotoxic cells and alloantibody. These responses were not detectable during pregnancy but appeared immediately postpartum. The ability of pregnancy to induce memory cell formation was tested by allowing females one successful pregnancy before challenging them postpartum with allogeneic spleen cells. Kinetic studies of cytotoxic cell production showed that C57BL/10 females that had borne (C57BL/10 X CBA/Ca)F1 litters responded earlier than their syngeneically mated sisters giving a peak response at 4 days compared to 7 days after immunization. This indicates that a single allogeneic pregnancy can prime the mother against paternal alloantigens suggesting that the conceptus is weakly immunogenic.

Animals↗
PubMed1983

Interaction of 3'-[3H]2'-Chloro-2'-deoxyuridine 5'-triphosphate with ribonucleotide reductase from Lactobacillus leichmannii.

Incubation of [3'-3H]2'-chloro-2'-deoxyuridine 5'-triphosphate (CldUTP) with adenosylcobalamin (AdoCbl), reductant, and ribonucleotide reductase from Lactobacillus leichmannii results in the production of 3H2O, uracil, tripolyphosphate, 5'-deoxyadenosine, and cob(II)alamin. The rate of 3H2O release (0.19 mumol/min/mg) is almost identical with the rate of UTP reduction (0.24 mumol/min/mg). The amount of 3H2O release is dependent upon the enzyme to cofactor ratio. With a ribonucleotide reductase: AdoCbl ratio of 1:1000, approximately 500 eq of 3H2O are released. At this time the enzyme is still active, but further destruction of cofactor and turnover of CldUTP is prevented by competitive inhibition of Co(II) + 5'-deoxyadenosine with AdoCbl for binding to ribonucleotide reductase. The 5'-deoxyadenosine and AdoCbl reisolated during incubation of [3'-3H]CldUTP and ribonucleotide reductase contains no detectable radioactivity.

Cobamides↗
PubMed1983

Identification of a heparin activated amidolytic enzyme in carp (Cyprinus carpio) plasma.

A heparin activated amidolytic enzyme capable of cleaving synthetic thrombin sensitive chromogenic substrates was identified from the plasma of the carp (Cyprinus carpio). Activation was inhibited by KCl, protamine sulphate and human plasma. Heparin was not required for the continued action of the enzyme. Active enzyme was irreversibly inhibited by DFP. The pH and temperature optima was studied and the enzyme semi purified by Sephadex G100 superfine and Sephadex A50 chromatography. An approximate MW of 62,000 was found. Activity generated by as little as 0.002 units of heparin per ml carp plasma was detected. The trivial name carpamidase is proposed for the enzyme.

Animals↗
PubMed1983

The amino-acid composition of the non-collagenous organic matrix of human cementum.

Human cementum was demineralized and exhaustively extracted with EDTA and then digested with collagenase. The insoluble residue after digestion was extracted successively with 8M urea and with 8M urea containing 0.1M mercaptoethanol. The non-collagenous fraction accounted for a larger proportion of the total organic matrix than previously found in bone and dentine, largely due to the presence of more collagenase-insoluble material. Fractionation of the EDTA-soluble material resulted in less-acidic fractions, showing similarities to the corresponding fractions of bone and dentine, and anionic fractions with lower levels of acidic amino acids than those from other hard tissues. Fractions obtained from the soluble collagenase-released material after ion-exchange chromatography and gel filtration, although more heterogeneous than those of bone and dentine, showed many similarities, thus confirming the close homology within this fraction from the various hard tissues. The insoluble residue after collagenase digestion appeared to be of the acid-structural protein type found also in bone, dentine and a wide range of connective tissues.

Amino Acids↗
PubMed1983

In vitro susceptibility of mouse placental trophoblast to cytotoxic effector cells.

The susceptibility of mouse placental cells to hyperimmune cell killing directed against paternal combined H-2 and non-H-2 antigens was investigated using [3H]uridine as a terminal label in an in vitro cell-mediated microcytotoxicity test. The stage of development of the conceptus from which the short-term placental cell monolayers were prepared determined their susceptibility to immune cell lysis. Cultures from whole placentae taken at 9 days post-coitum (p.c.) were not significantly affected whereas similar monolayers prepared at 10.5 days p.c. or later underwent extensive destruction. Embryonic fibroblasts were susceptible at all stages examined from 9-16 days p.c. The onset of susceptibility correlates with the reported appearance of H-2 antigens on the placenta during ontogeny. All cultures of dissected populations of 13-day p.c. placental spongiotrophoblast were susceptible but only 70% of those of labyrinthine trophoblast. It is suggested that of the two major trophoblastic components of the mouse placenta the spongiotrophoblast expresses antigens that render it vulnerable to maternal immune attack whilst the labyrinthine trophoblast is only weakly or non-antigenic, with the observed killing being due largely to contamination of these cultures by antigenic foetal mesenchymal elements. Since failure to express appropriate target antigens cannot be the reason for the in vivo survival of the spongiotrophoblast it must be presumed that some form of immunoregulatory mechanism(s) is responsible for the maintenance of the foeto-placental allograft.

Animals↗
PubMed1983

Antibiotic activity in peritoneal dialysate.

There are few studies investigating whether antibiotics added to 30% glucose concentrate preserve their activity in the delivered dialysate. Using a Drake-Willock proportioning system, samples were obtained from the "to" patient path at ten minutes after starting and at four hours. Samples were tested for minimal inhibitory dilution (MID) against Escherichia coli and Staphylococcus aureus. Antibiotics evaluated included amikacin, tobramycin, gentamicin, cephalothin, cefamandole, moxalactam, ampicillin, penicillin, carbenicillin, and vancomycin. In all antibiotics studied, similar MIDs were obtained at the ten-minute and four-hour samples. Compared to saline, dialysate significantly impaired the antibiotic activity (a difference of two or more tube dilutions) of all antimicrobial agents except amikacin and vancomycin.

Anti-Bacterial Agents↗
PubMed1983

Effect of chronic administration of fenfluramine and quipazine on body weight gain after ovariectomy and on brain serotonin receptor binding.

Chronic fenfluramine administration prevented excess weight gain following ovariectomy in rats but did not alter weight gain in sham-operated controls. Chronic quipazine treatment had no long-term effect on body weight. In one experiment, fenfluramine treatment for 28 days produced a 13% decrease in [3H]-serotonin binding to hypothalamic membranes and no change in [3H]-spiroperidol binding to striatum. In a second experiment, however, chronic fenfluramine had no effect on [3H]-serotonin binding to diencephalon. These results are discussed in terms of central and peripheral mechanisms of action and tolerance to fenfluramine.

Animals↗