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Biomedical subjects

W Thompson

Publications and source records attributed to W Thompson.

At least 55 records · Page 3Linked to original sources
PubMed1996

Nitric oxide synthase and nitrite production in human spermatozoa: evidence that endogenous nitric oxide is beneficial to sperm motility.

The aim of this study was to investigate the presence of nitric oxide synthase (NOS) and the production of nitric oxide (NO) by human spermatozoa. Immunoreactivity was examined using a polyclonal antibody raised against porcine cerebellar nitric oxide synthase and monoclonal endothelial (eNOS) and brain (bNOS) antibodies. Using each antibody, NOS was observed localized in the head and midpiece regions of the spermatozoon. Immunofluorescence observed for eNOS and bNOS was more intense in normozoospermic samples. Sperm motility was assessed by computer-assisted semen analysis (CASA) in the presence and absence of NG-nitro-L-arginine methyl ester (L-NAME; 10(-5)M), and NO synthesis inhibitor or tumour necrosis factor (TNF)-alpha (20 IU/ml), a superoxide inducer. In the presence of L-NAME, percentage progressive motility, average path velocity (VAP), straight line velocity (VSL) and curvilinear velocity (VCL) were significantly reduced after 30 min. Sperm viability was not decreased by TNF alpha or L-NAME. The accumulation of nitrite (the stable end-product of the NOS/NO pathway) by spermatozoa was measured using the Griess reaction. After 8 h, nitrite concentrations were lower in asthenozoospermic compared to normozoospermic samples. In the presence of TNF alpha, nitrite accumulation was significantly reduced in normozoospermic samples. We conclude that NOS is present in human spermatozoa and that eNOS and bNOS are abundant in normozoospermic samples. Nitric oxide (at endogenous concentrations) appears to be necessary for adequate sperm motility.

Animals↗
PubMed1996

A comparison of baseline and induced DNA damage in human spermatozoa from fertile and infertile men, using a modified comet assay.

Baseline DNA damage in spermatozoa from fertile and infertile men was compared using a modified alkali single cell gel electrophoresis (comet) assay. Semen from normozoospermic fertile, normozoospermic infertile and asthenozoospermic infertile (World Health Organization criteria, 1992) samples were studied. No significant difference was observed in levels of baseline damage between the three groups. A median value for baseline damage of approximately 20% (80% head DNA) was obtained in all samples. Irradiation with X-rays (5-30 Gy) produced no additional damage in fertile samples when median values were examined. However, irradiation with 30 Gy X-rays produced significant damage in both infertile groups. Hydrogen peroxide (40 microM) treatment induced significant damage in the asthenozoospermic group, whereas 100 microM H2O2 was required to cause significant damage in the normozoospermic fertile and infertile samples. Within the fertile population a subgroup in which percentage head DNA was greater than 80% was observed in both treated and untreated specimens. This subgroup significantly decreased with treatment in both infertile groups. We conclude that the asthenozoospermic infertile group is more susceptible to damage than the normozoospermic infertile group, which in turn is more susceptible than the fertile group. The fertile group contains a resistant subpopulation of spermatozoa with relatively intact DNA.

DNA↗
PubMed1996

The passing score in the objective structured clinical examination.

The objective structured clinical examination (OSCE) now has an established place in the assessment of the medical undergraduate. While much has been written about the reliability of the OSCE, empirical work on the determination of the passing score which represents competence on the OSCE is rarely encountered. If the OSCE is to play its role in the 'high stakes' testing of clinical competence, it is important that this passing score be set reliably and defensibly. This article illustrates how a two-session modified Angoff standard-setting procedure is used to set the passing score on a 14 station Obstetrics and Gynaecology OSCE used to assess final year students at The Queen's University of Belfast. The Angoff methodology harnesses the professional judgement of expert judges to establish defensible standards. Four university teachers, five non-academic consultants and six junior clinical staff took part in a two-session Angoff standard-setting procedure. In the first session, the judges (individually and in silence) used their professional judgement to estimate the score which a minimally competent final year obstetrics and gynaecology student should achieve on each tested element of the OSCE. In the second session they revised their session 1 judgements in the light of the OSCE scores of real students and the opportunity for structured discussion. The passing score for the OSCE is reported together with the statistical measures which assure its reliability.

Clinical Competence↗
PubMed1996

Young children's cardiovascular stress responses predict resting cardiovascular functioning 2 1/2 years later.

BACKGROUND: Since the pathogenesis of coronary heart disease (CHD) has its origins in childhood, researchers have increasingly evaluated CHD risk factors in youth. In this study we examined the hypothesized behavioral risk factor of cardiovascular responsivity as a predictor of very young children's resting cardiovascular functioning 2 1/2 years later. SUBJECTS AND METHODS: During an initial visit to the laboratory, 97 children (30 blacks and 67 whites, 45 boys and 52 girls) aged 6-7 years completed three laboratory stressor tests (forehead cold pressor, postural change, and treadmill exercise). A comprehensive cardiovascular assessment was conducted during the tests. Resting cardiovascular activity (baseline values) was also assessed. Follow-up resting cardiovascular parameters were measured in the laboratory 2 1/2 years later. RESULTS: Cardiovascular stress responses were predictive of cardiovascular follow-up resting levels 2 1/2 years later. Multiple regression was used to evaluate the independent predictive power of stress responses after controlling for traditional risk factors. Follow-up resting systolic blood pressure (SBP) was predicted by the SBP response to postural change and treadmill exercise. Follow-up resting diastolic blood pressure (DBP) was predicted by the DBP response during treadmill exercise, particularly for blacks. The follow-up resting heart rate was predicted by the heart rate response to the forehead cold pressor and treadmill exercise. CONCLUSION: These results show that in very young children, stress responses are predictive of resting cardiovascular functioning 2 1/2 years later. Further developmental and longitudinal investigations will determine whether such responses are predictive of later preclinical manifestations of cardiovascular disease. If so, incorporation of stress testing in a standardized risk identification protocol might aid the design and practice of cardiovascular preventive medicine.

Analysis of Variance↗
PubMed1995

Estrogen replacement therapy in practice: trends and issues.

Since their availability in 1926, estrogens and their use in postmenopausal women have met with both acceptance and alarm by the medical profession and potential estrogen users. It was not until the 1980s that long-term research began to demonstrate the beneficial effects of estrogen, thus contributing to a significant increase in use during the past decade. This article provides information on current use of estrogen replacement therapy and describes factors influencing continuance. Poor continuance remains a barrier to the full potential of estrogen replacement therapy for postmenopausal women. The role of the physician in improving continuance is discussed.

Aged↗
PubMed1995

Successful pregnancy in association with Zollinger-Ellison syndrome.

Persistent severe vomiting in pregnancy may be caused by underlying disease and should be investigated. A patient with intractable vomiting associated with abdominal pain and dental enamel erosion in two pregnancies had a gastrinoma. Symptoms were successfully controlled with omeprazole in a third pregnancy. All three babies were healthy.

Adult↗
PubMed1995

Total antioxidant capacity of seminal plasma is different in fertile and infertile men.

OBJECTIVE: To determine if the total antioxidant capacity of seminal plasma is different in fertile and infertile men. DESIGN: An enhanced chemiluminescence assay applied to seminal plasma from groups of fertile and infertile men. SETTING: The Assisted Conception Unit, Royal Maternity Hospital, Belfast. SUBJECTS: Men of proven fertility whose partners had an ongoing pregnancy resulting from IVF and male partners of couples attending our subfertility clinic. RESULTS: Total antioxidant capacity was significantly higher in seminal plasma from fertile men than from that of infertile men with normozoospermic samples that exhibited reactive oxygen species or asthenozoospermic samples with or without reactive oxygen species activity. CONCLUSIONS: Seminal plasma from infertile men has lower antioxidant levels than that of fertile men, particularly of patients whose semen have poor sperm motility. The presence of reactive oxygen species activity in sperm of infertile groups also is associated with lower levels of chain-breaking antioxidants in seminal plasma.

Fertility↗
PubMed1995

Using alcohol as a standard to assess the degree of impairment induced by sedative and analgesic drugs used in ambulatory surgery.

BACKGROUND: There is a need for a standard by which to compare the degree of subjective and behavioral impairment caused by anesthetic drugs, because anesthesiologists may not be able to gauge how extreme or important a statistically significant change in psychomotor functioning is. This study examined the psychomotor and subjective effects of alcohol at blood concentrations equal or greater than 0.10% as a standard with which to compare those effects caused by sedative and analgesic agents commonly used in ambulatory surgery. METHODS: Twelve healthy human volunteers (11 men and 1 nonpregnant woman), with an average age of 28 yr (range 24-34 yr) and an average alcohol consumption of four drinks per week, were selected in this institutional review board-approved study. Each subject was exposed to five drug conditions (70 mg/70 kg propofol intravenously, 2 mg/70 kg midazolam intravenously, 50 micrograms/70 kg fentanyl intravenously, 0.8 g/kg alcohol orally, and placebo orally and intravenously) in a double-blind randomized fashion over five weekly sessions. Testing was done at baseline and at different intervals until 240 min after drug administration. Testing included psychomotor performance (Maddox Wing, eye-hand coordination, auditory reaction time test, and digit symbol substitution test), subjective effects (strength of drug effect scale, drug liking scale, and visual analog scale), and short-term memory. Psychomotor performance was used as an index of objective impairment, and mood was used as an index of subjective impairment. RESULTS: After consumption of the alcoholic beverage, a blood alcohol level of 0.11 +/- 0.003% (mean +/- SE) was obtained at 15 min after injection. The study drugs not only produced statistically significant impairment (i.e., impairment greater than that seen with placebo) but also, at one or more times after injection, produced impairment similar to that observed with alcohol at a blood alcohol concentration of 0.11%. Midazolam produced a similar degree of impairment to that of alcohol for a longer duration than did fentanyl and propofol. CONCLUSIONS: This study provides evidence that degree of impairment caused by sedative and analgesic drugs used in ambulatory surgery is similar to that obtained with a dose of alcohol that produces a blood alcohol concentration of 0.11%. We suggest that anesthesiologists can use alcohol as a standard by which to assess degree of impairment produced by drugs used for sedation/analgesia.

Administration, Oral↗
PubMed1995

Crack cocaine mimicking pulmonary embolism on pulmonary ventilation/perfusion lung scan. A case report.

Cocaine inhalation is associated with multiple pulmonary complications including pulmonary infiltrates, pulmonary edema, barotrauma, tracheal injury, and alveolar hemorrhage. Little has been reported about ventilation/perfusion (V/Q) lung scanning in patients who smoke cocaine. The authors report a case of inhalation cocaine abuse mimicking pulmonary embolism by V/Q scan criteria. This case report documenting perfusion abnormalities within hours of cocaine smoking which resolved within days provides the first in vivo evidence for pulmonary vasoconstriction.

Adult↗
PubMed1995

A double-blinded prospective evaluation of recombinant human erythropoietin in acutely burned patients.

OBJECTIVE: To evaluate the effects of recombinant human erythropoietin (r-HuEPO) in attempting to prevent anemia in acutely burned patients. DESIGN: Prospective double-blind randomized study of 40 patients. METHODS: Patients with burns from 25% to 65% total body surface were enrolled. r-HuEPO or a placebo was begun within 72 hours of admission. Cell blood count, reticulocyte counts, transfusion requirements, and blood loss were measured. Comparison was carried out by the unpaired t test. MAIN RESULTS: There was no statistically significant difference in hemoglobin, hematocrit, reticulocyte count, ferritin, serum iron, total iron blinding capacity, or transfusion requirements. In patients with burns from 25% to 35%, the reticulocyte counts were statistically significantly higher. CONCLUSION: In our work the administration of r-HuEPO in acutely burned patients did not prevent the development of postburn anemia or decrease transfusion requirements. Increased erythropoiesis in smaller burns (25% to 35%) was observed and may indicate a reason for further study.

Adolescent↗
PubMed1995

Effect of glyceryl trinitrate on sperm motility and lipid peroxidation in normozoospermic men.

The objective of this study was to assess the in-vitro effects of the nitric oxide substrate glyceryl trinitrate (GTN) on sperm motility and membrane lipid peroxidation. Nitric oxide (NO) can impair sperm motility, possibly by an alteration of cyclic nucleotide levels. NO may also be protective against lipid peroxidation. Semen samples from nine normospermic men were prepared by a swim-up technique. Each specimen was divided into four aliquots, one of which was the control sample. The other three had 10(-6), 10(-8) or 10(-10) M GTN added. Sperm motility was then analysed over 180 min using a Hamilton Thorn motility analyser. Lipid peroxidation was assessed by measuring media malondialdehyde (MDA) levels at 180 min. Compared with control, the following measurements were reduced (p < 0.05) over the first 60 min in the 10(-6) M GTN aliquots only: mean path velocity (reduced by 14-15%), curvilinear velocity (reduced by 12-21%), straight-line velocity (reduced by 18-19%) and percentage of hyperactivated spermatozoa (reduced by 38-43%). MDA levels and head movement parameters were comparable amongst all aliquots (p > 0.05). The depressant effects of GTN on sperm motility appeared to be transient and reversible. The effects observed may be due to NO generated by GTN, or to GTN itself. This suggests that NO may have a role in vivo as a physiological inhibitor of sperm motility. The addition of GTN did not appear either to cause sperm membrane damage or to protect the spermatozoa from lipid peroxidation.

Cell Membrane↗
PubMed1995

N of 1 study: amantadine for the amotivational syndrome in a patient with traumatic brain injury.

Severe amotivation, apathy, and abulia, significantly retard rehabilitation following traumatic brain injury. Preliminary, uncontrolled research has suggested possible benefit with amantadine for this behavioural syndrome. This N of 1, double-blind, placebo-controlled study employed amantadine 100 mg three times daily in one such patient. Therapists and nurses completed inventories scoring efforts towards initiation of therapeutic activities during each session, progress in therapy, and participation in therapy. Four treatment periods (two active medication, two placebo), of 2 weeks duration, were completed. Across four therapists, and for both treatment pairs, the average effect score increased from 0.86 on placebo to 1.74 on amantadine (possible range 0-6, 3 = 'average'). There were no side-effects. The study suggests possible benefit with amantadine for patients with amotivational syndrome after traumatic brain injury; a randomized clinical trial appears warranted and required.

Adult↗
PubMed1995

Massive overdose of sustained-release verapamil: a case report and review of literature.

Verapamil 99 is a commonly prescribed medicine for treatment of hypertension, angina, and migraine headache. Toxicity with sustained-release verapamil may be prolonged, and manifest with hypotension, bradycardia, metabolic acidosis, and hyperglycemia. Currently, because of the lack of a specific antidote management of verapamil, toxicity is mainly supportive. Treatment with inotropic support, glucagon, calcium, and cardiac pacing may be effective in some cases. A review of 20 cases and a case report of sustained-release verapamil overdose are described. The authors describe a patient who ingested 24 g of slow-release verapamil. This is the largest overdose of sustained-release verapamil reported in English literature. The patient was managed aggressively with gastric lavage, inotropic support, and continuous infusion of calcium and glucagon. The patient's survival may have been due to the continuous intravenous calcium gluconate and glucagon infusion. Both of these treatment modalities should be considered in patients with moderate to severe calcium channel blocker overdose.

Calcium Gluconate↗
PubMed1994

Modulation of hepatic mRNA levels after administration of lipopolysaccharide and diphtheria and tetanus toxoids and pertussis vaccine adsorbed (DTP vaccine) to mice.

Administration of whole-cell diphtheria and tetanus toxoids and pertussis vaccine adsorbed (DTP vaccine) caused marked depression in the expression of mRNA for isozymes of cytochrome P-450 in the livers of endotoxin-responsive and nonresponsive mice. The levels of expression of mRNA for a polycyclic aromatic hydrocarbon-inducible (CYP1A2) and an ethanol-inducible (CYP2E1) form of P-450 were reduced by 70% to 80% 8 to 12 hr after vaccination or Bordetella pertussis endotoxin administration. These effects are preceded by marked increases (threefold to sixfold) in mRNA expression for interleukin-6, interleukin-1 and tumor necrosis factor in both strains of mice, with maximal increases 1 to 2 hr after injection. This is the first demonstration that levels of cytokine mRNA are altered in the liver in response to DTP vaccine administration. The finding of increased cytokine mRNA in the livers of mice injected with vaccine supports a role for cytokines as mediators of the decreased levels of cytochrome P-450. In addition, inducible nitric oxide synthase mRNA expression is also increased after vaccine administration, with a peak at 4 hr. The temporal relationship of the increased cytokine mRNA expression, increased nitric oxide synthase and decreased expression of P-450 mRNAs suggests a mechanism by which cytokines mediate the induction of nitric oxide synthase, which increases nitric oxide and decreases the activities of some cytochromes P-450.

Amino Acid Oxidoreductases↗
PubMed1994

An outbreak of parvovirus B19 infection; a study of clinical manifestations and the incidence of fetal loss.

Eighty-five cases of B19 infection were diagnosed in Northern Ireland from 1984 to 1989; 65 of these occurred during 1989, the outbreak year. Of the total 85 cases, 15 had a rash, 21 had arthralgia, 47 had a rash and arthralgia, and 2 had aplastic crisis. The age range was 4-63 years with a mean of 26.9 years. Thirty cases (35%) were referred to hospital; 25 of these had arthralgia and 2 had aplastic crisis. Two thousand four hundred pregnant women at 12 weeks gestation in 1989 were screened for anti-B19 IgM; 8 were positive. Of these 8 patients, 7 progressed to delivery of a normal fetus and one had an intra-uterine death at 26 weeks gestation; no congenital abnormalities were noted in any fetus. The incidence of fetal involvement in maternal B19 infection in this study was therefore 12.5%.

Adolescent↗
PubMed1994

The influence of peritoneal fluid from patients with minimal stage or treated endometriosis on sperm motility parameters using computer-assisted semen analysis.

The aim of this study was to determine the influence of peritoneal fluid from patients with minimal stage or treated endometriosis on sperm motility parameters. Peritoneal fluid aspirated at diagnostic laparoscopy for unexplained infertility from women during the luteal phase of the menstrual cycle (days 20-23) was incubated for 5 h with fresh semen samples obtained from men of recently proven fertility. Spermatozoa were prepared by a swim-up technique from unprocessed semen. Using computer-assisted semen analysis (Hamilton-Thorn Research, MA, USA), sperm motility and motion parameters were observed at 0, 120, 180 and 300 min. Compared with spermatozoa incubated in Earle's balanced salt solution/human serum albumin, the percentage motility, percentage progressive motility and progressive velocity of spermatozoa incubated in peritoneal fluid from patients without visible endometriosis were significantly higher (P < 0.05). Maximal effect was observed at 3 h and maintained until 5 h. We conclude that in an in-vitro study, in contrast to peritoneal fluid from patients with minimal stage endometriosis, peritoneal fluid from patients with unexplained infertility and no visible endometriosis can improve sperm motility when compared with culture medium.

Adult↗
PubMed1994

Comparison of Neuropsychological Test Performance in PTSD, Generalized Anxiety Disorder, and Control Vietnam Veterans

Although impairment in cognitive functioning is theoretically linked to the presence of post-traumatic stress disorder (PTSD), the actual impact of this disorder on neuropsychological performance remains largely unknown. While a modest amount of empirical attention has been directed toward examining the neuropsychological correlates of PTSD, several methodological problems, most notably small sample sizes and the resulting lack of power, have greatly restricted generalizability of findings. The present study examined the neuropsychological performance pattern of Vietnam veterans with PTSD (n = 241) as compared to those with generalized anxiety disorder (n = 241) and no history of psychiatric diagnosis (n = 241). A one-way MANOVA revealed no significant differences among the groups on any of the dependent measures of cognitive functioning, including the Wechsler Adult Intelligence Scale-Revised Block Design subtest, the California Verbal Learning Test, the Rey-Osterrieth Complex Figure Drawing Test, and the Paced Auditory Serial Addition Test. The results are reconciled as they relate to previous research examining the theoretical constructs of PTSD, clinical applications, and directions for future research.

Journal Article↗