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Biomedical subjects

G L Harrison

Publications and source records attributed to G L Harrison.

11 recordsLinked to original sources
PubMed1995

Differentiation of dextran-producing Leuconostoc strains from fermented rice cake (puto) using pulsed-field gel electrophoresis.

Lactic acid bacteria were isolated from puto, a fermented rice cake consumed as a breakfast and snack food in the Philippines. The microflora was dominated by dextran-producing leuconostocs, and these were differentiated into four groups using pulsed-field gel electrophoresis of restriction enzyme digested chromosomal DNA, in conjunction with taxonomic tests. The four groups corresponded to the species Leuconostoc mesenteroides subsp. mesenteroides, Leuconostoc pseudomesenteroides, Leuconostoc citreum and Leuconostoc fallax. Several strains showed an unusual clumping phenotype, and two of these were capable of inhibiting other strains of lactic acid bacteria.

Bacteriocins↗
PubMed1994

Urinary incontinence in women: its prevalence and its management in a health promotion clinic.

BACKGROUND: It has been suggested that regular clinics might improve the management of urinary incontinence in general practice. AIM: A study was undertaken to determine the prevalence of urinary incontinence among women in one general practice and the feasibility of using a health promotion clinic in its management. METHOD: Questionnaires were sent to a 10% sample of women aged 20 years and over on the practice register. Pregnant women were excluded. RESULTS: Of 384 questionnaires sent to eligible women, 314 were completed correctly (82%). The overall reported prevalence of urinary incontinence was 53%; 8% of these women had urge incontinence, 46% had stress incontinence and 43% had mixed incontinence. Incontinence was positively correlated with parity and with gynaecological operation other than hysterectomy and repair of prolapse but not with perineal suturing after childbirth, delivery of a baby weighing 9 lb (4.1 kg) or more or mode of delivery. Twenty seven out of 78 incontinent women (35%) who completed a second questionnaire admitted to worrying about their incontinence but only 10 (13%) had consulted their doctor about the problem. The main reason given for not consulting was that incontinence was a minor inconvenience only. The 167 incontinent women were offered an appointment at a women's clinic but only 13 attended. Of these, 10 were entered into a 12 week treatment trial. Various treatments were offered, such as the women being taught bladder training and pelvic floor exercises. One woman was lost to follow up, and for eight out of nine women their continence had improved, both subjectively and objectively. CONCLUSION: Urinary incontinence in women is a common problem. It can be successfully diagnosed and treated in general practice but low attendance makes the health promotion clinic setting an inefficient means of achieving this.

Adult↗
PubMed1990

Systemic vascular reactivity during high-altitude pregnancy.

There is an increased incidence of preeclampsia at high compared with low altitude. Increased vasoreactivity, possibly due to a deficiency of vasodilator prostaglandins, is thought to contribute to the etiology of preeclampsia. We sought to determine whether high-altitude exposure increased systemic vascular reactivity during pregnancy. We measured systemic vascular reactivity and contractile sensitivity of isolated aortic rings from pregnant and nonpregnant guinea pigs kept for 6 wk at either simulated high altitude (3,900 m) or low altitude (1,600 m). We found that pregnancy at high compared with low altitude increased baseline systemic vascular resistance (SVR) but not the SVR response to angiotensin II in awake unstressed guinea pigs. Contractile sensitivity to norepinephrine was also increased in aortic rings isolated from high-altitude compared with low-altitude pregnant animals. Meclofenamate, a prostaglandin synthesis inhibitor, did not equalize vasoreactivity in the high- and low-altitude pregnant guinea pigs or in their isolated aortic rings. We concluded that pregnancy at high compared with low altitude increased base-line SVR and aortic contractile sensitivity but that mechanisms other than decreased vasodilator prostaglandin production were responsible.

Altitude↗
PubMed1989

Blunted vasoreactivity in pregnant guinea pigs is not restored by meclofenamate.

Pregnant women show a reduced pressor responsiveness to angiotensin II, but the mechanism responsible in unclear. We sought to determine whether reduced pressor responsiveness was due to decreased vasoreactivity and the involvement of increased vasodilator prostaglandin production in decreases observed. We found that pregnancy decreased systemic vascular resistance and the systemic vascular resistance response to angiotensin II infusion but not to phenylephrine hydrochloride infusion in awake, unstressed guinea pigs. The decreased systemic vascular resistance response to angiotensin II in the pregnant animals was accompanied by a reduced pressor response. Contractility to phenylephrine hydrochloride and norepinephrine was reduced in aortic rings isolated from pregnant, compared with nonpregnant, guinea pigs. Treatment with meclofenamate, a prostaglandin synthesis inhibitor, did not restore vasoreactivity in either the pregnant animal or the isolated vessel to levels observed in the nonpregnant state. We concluded that pregnancy reduced systemic vascular resistance and vasoreactivity but that mechanisms other than increased vasodilator prostaglandin production were likely responsible.

Angiotensin II↗
PubMed1988

Abnormal control of ventilation in high-altitude pulmonary edema.

We wished to determine the role of hypoxic chemosensitivity in high-altitude pulmonary edema (HAPE) by studying persons when ill and upon recovery. We studied seven males with HAPE and seventeen controls at 4,400 m on Mt. McKinley. We measured ventilatory responses to both O2 breathing and progressive poikilocapnic hypoxia. Hypoxic ventilatory response (HVR) was described by the slope relating minute ventilation to percent arterial O2 saturation (delta VE/delta SaO2%). HAPE subjects were quite hypoxemic (SaO2% 59 +/- 6 vs. 85 +/- 1, P less than 0.01) and showed a high-frequency, low-tidal-volume pattern of breathing. O2 decreased ventilation in controls (-20%, P less than 0.01) but not in HAPE subjects. The HAPE group had low HVR values (0.15 +/- 0.07 vs. 0.54 +/- 0.08, P less than 0.01), although six controls had values in the same range. The three HAPE subjects with the lowest HVR values were the most hypoxemic and had a paradoxical increase in ventilation when breathing O2. We conclude that a low HVR plays a permissive rather than causative role in the pathogenesis of HAPE and that the combination of extreme hypoxemia and low HVR may result in hypoxic depression of ventilation.

Adult↗
PubMed1987

Inhibition of neutrophil myeloperoxidase activity by selected tissues.

Myeloperoxidase, a polymorphonuclear leukocyte-specific enzyme, has been used previously to quantify the number of polymorphonuclear leukocytes in tissue. When this method was employed in an attempt to measure polymorphonuclear leukocyte numbers in infected kidneys, it was found that myeloperoxidase could not be demonstrated, although significant numbers of neutrophils were present in the pyelonephritic lesions. Further studies were carried out to determine the effect of other tissues on free and cell-bound exogenous myeloperoxidase. We have shown that while skin had little effect on enzyme levels, liver and spleen totally destroyed myeloperoxidase activity within 30 sec. Cardiac and striated muscle had an intermediate effect. When intact neutrophils were added to fresh cardiac tissue 72.5% myeloperoxidase activity was destroyed during the enzyme solubilization procedure. These findings indicate that the technique can only be used for the quantification of polymorphonuclear leukocytes in selected tissues and that appropriate controls are essential. Previous studies in which myeloperoxidase levels have been used to estimate polymorphonuclear leukocyte numbers in cardiac tissue will need reevaluation.

Animals↗
PubMed1987

Respiratory stimulants and sleep periodic breathing at high altitude. Almitrine versus acetazolamide.

We studied the effects of almitrine, acetazolamide, and placebo on the hypoxic ventilatory response (HVR), sleep periodic breathing, and arterial oxygen saturation (SaO2) in 4 healthy climbers. In a laboratory on Denali (Mt. McKinley) at 4,400 m (PB = 440 mm Hg), we used a double-blind, randomized, three-way crossover design. The HVR was measured during the waking state. Periodic breathing and SAO2% were measured during 3-h sleep studies. Almitrine and acetazolamide both increased SaO2% during sleep, although almitrine increased periodic breathing, whereas acetazolamide decreased periodic breathing. The HVR (delta VE/delta SaO2%) was doubled with almitrine (p less than 0.05), but unchanged with acetazolamide. The HVR was positively related to periodic breathing (p less than 0.05). We conclude that periodic breathing during sleep at high altitude is related to the hypoxic ventilatory response, and that acetazolamide is a superior agent to almitrine for ameliorating periodic breathing.

Acetazolamide↗
PubMed1986

Meclofenamate potentiates vasoreactivity to alpha-adrenergic stimulation in chronically hypoxic guinea pigs.

The aim of this study was to examine the effect of chronic hypoxia on systemic vascular reactivity and the role of prostaglandins in modulating the vascular response to chronic hypoxia. Meclofenamate, a prostaglandin synthesis inhibitor, increased the systemic vascular resistance response to the alpha-adrenergic agonist, phenylephrine, in awake, unrestrained guinea pigs exposed for 6 wk to high altitude (3,900 m), but it did not alter the response in animals kept at low altitude (1,600 m). The systemic vascular resistance response to phenylephrine before treatment with meclofenamate was the same in high- and low-altitude animals. Meclofenamate also increased the contractile response to phenylephrine in aortic rings isolated from high- but not low-altitude animals. The systemic vascular resistance response to angiotensin II was the same in high- and low-altitude animals, and meclofenamate increased this response to the same extent in both groups. Thus chronic hypoxia appeared to enhance vascular production of dilator prostaglandins during beta-adrenergic stimulation.

Adrenergic alpha-Agonists↗
PubMed1986

Low acute hypoxic ventilatory response and hypoxic depression in acute altitude sickness.

Persons with acute altitude sickness hypoventilate at high altitude compared with persons without symptoms. We hypothesized that their hypoventilation was due to low initial hypoxic ventilatory responsiveness, combined with subsequent blunting of ventilation by hypocapnia and/or prolonged hypoxia. To test this hypothesis, we compared eight subjects with histories of acute altitude sickness with four subjects who had been asymptomatic during prior altitude exposure. At a simulated altitude of 4,800 m, the eight susceptible subjects developed symptoms of altitude sickness and had lower minute ventilations and higher end-tidal PCO2's than the four asymptomatic subjects. In measurements made prior to altitude exposure, ventilatory responsiveness to acute hypoxia was reduced in symptomatic compared to asymptomatic subjects, both when measured under isocapnic and poikolocapnic (no added CO2) conditions. Diminution of the poikilocapnic relative to the isocapnic hypoxic response was similar in the two groups. Ventilation fell, and end-tidal PCO2 rose in both groups during 30 min of steady-state hypoxia relative to values observed acutely. After 4.5 h at 4,800 m, ventilation was lower than values observed acutely at the same arterial O2 saturation. The reduction in ventilation in relation to the hypoxemia present was greater in symptomatic than in asymptomatic persons. Thus the hypoventilation in symptomatic compared to asymptomatic subjects was attributable both to a lower acute hypoxic response and a subsequent greater blunting of ventilation at high altitude.

Adult↗