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Biomedical subjects

W Thompson

Publications and source records attributed to W Thompson.

At least 73 records · Page 4Linked to original sources
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↗
PubMed1993

Association of Chlamydia trachomatis with tubal infertility.

A study was undertaken to determine whether the positive correlation between Chlamydia trachomatis antibodies and tubal infertility, noted by workers in other countries, also applied to infertile women in Northern Ireland. Ninety-one infertile women and 106 fertile controls were tested for current cervical infection with C. trachomatis and for evidence of past chlamydial infection. The incidence of C. trachomatis infection of the cervix was 5.8% in the infertile group and 2.8% in the control group. The prevalence of C. trachomatis antibody was 22% in the infertile group and 18.9% in the control group. Previous termination of pregnancy, history of sexually transmitted disease and number of sexual partners were identified as risk factors for seropositivity and tubal disease. We concluded that it would be of value to screen women attending the infertility clinic for C. trachomatis infection of the cervix, and that testing these patients for chlamydia antibodies may also be useful in planning further investigation.

Adult↗
PubMed1993

Inositol trisphosphate restores impaired human gallbladder motility associated with cholesterol stones.

BACKGROUND: Gallbladder motility is impaired in specimens with cholesterol stones but normal with pigment stones. METHODS: Muscle cells obtained from 19 human gallbladders with cholesterol stones and 11 with pigment stones were enzymatically digested and contracted with cholecystokinin octapeptide (CCK-8), acetylcholine, and KCl. RESULTS: Muscle cells from pigment stones had a greater contraction than cells from cholesterol stones. CCK-8-induced contraction was unaffected by calcium-free media but was blocked by strontium. Potassium-evoked contraction was blocked by a calcium-free media and unaffected by strontium. Inositol triphosphate (IP-3)-induced contraction was similar to the contraction caused by CCK-8 in permeable cells from pigment stones but was greater than the response to CCK-8 in cells from cholesterol stones. CONCLUSIONS: Muscle cells from gallbladders with cholesterol stones contract less than cells from gallbladders with pigment stones; CCK-8-induced contraction only uses stored calcium; and IP-3 causes contractions of equal magnitude in cells from gallbladders with cholesterol and pigment stones. These abnormalities could result from an impaired receptor activation of the mechanism for IP-3 generation and release of stored calcium.

Acetylcholine↗
PubMed1993

Effects of pentoxifylline on human sperm motility in normospermic individuals using computer-assisted analysis.

OBJECTIVE: To determine if pentoxifylline has an in vitro effect on human sperm motility in subjects with normal semen analysis. DESIGN: Prospective, longitudinal study of the effect of pentoxifylline on normospermic semen samples using computerized analysis. SETTING: The Assisted Conception Unit, Royal Maternity Hospital, Belfast. SUBJECTS: Eight healthy male volunteers of proven fertility within 2 years of study and whose general health was unchanged in the intervening period. RESULTS: Pentoxifylline did not consistently increase the number of progressively motile sperm or their straight line velocity (VSL). In marked contrast, the curvilinear velocity (VCL) was increased significantly at all times, up to and including 240 minutes of exposure to the drug. This resulted in a substantial reduction in the linearity (VSL/VCL) of sperm progression. The most dramatic effect that pentoxifylline had on sperm movement was to increase the amplitude of lateral head displacement (ALH) over the same time interval. This change was accompanied by an increase in the beat cross frequency. CONCLUSIONS: The addition of pentoxifylline to prepared sperm samples from normospermic men does not increase the number of progressively motile sperm nor the progressive velocity. However, it does significantly alter the quality of certain characteristics of already motile sperm.

Electronic Data Processing↗
PubMed1993

Klebsiella pneumoniae infection on a rehabilitation unit: comparison of epidemiologic typing methods.

OBJECTIVE: To identify factors associated with an increased occurrence of Klebsiella pneumoniae isolation in urine cultures and infected wounds on a rehabilitation unit and to compare typing methods for K pneumoniae isolates. DESIGN: Retrospective review of laboratory reports and patient records with case-control study. Analysis of K pneumoniae isolates using capsular serotyping, enzyme electrophoretic typing, ribotyping, and DNA typing. SETTING: 48-bed rehabilitation unit in an 1,100-bed tertiary care teaching hospital in Winnipeg, Manitoba. RESULTS: In 1988, 20 (19%) of 106 patients admitted to the rehabilitation unit had K pneumoniae isolated from urine or wound, and in 1989 31 (28%) of 111 patients had Klebsiella isolated. Review of ward practices revealed appropriate written policies but evidence of failure in execution leading to multiple opportunities for transmission among patients. Substantial environmental contamination was not identified, although a common urine graduate may have contributed to some transmission. Individuals with K pneumoniae isolated had a significantly longer duration of stay. Many of these were spinal cord-injured patients and were maintained on intermittent catheterization. One outbreak strain was identified in epidemiologic typing. Other strains were generally identified in individuals with non-nosocomial acquisition of infection. Comparison of epidemiologic typing methods suggests ribotyping may be the optimal method for typing K pneumoniae strains. CONCLUSIONS: K pneumoniae was acquired frequently by spinal cord-injured patients with extended admissions, re-emphasizing the importance of both patients and staff following appropriate infection control practices on rehabilitation wards. Ribotyping was the optimal method for typing K pneumoniae isolates.

Adult↗
PubMed1993

Pertussis toxin-induced alterations of murine hepatic drug metabolism following administration of diphtheria and tetanus toxoids and pertussis vaccine adsorbed.

Administration of pertussis toxin (PT) in combination with diphtheria and tetanus toxoids adsorbed (DT vaccine) or with acellular pertussis vaccine adsorbed and diphtheria and tetanus toxoids (APDT) elicits dose- and time-dependent alterations in hepatic drug metabolism in mice. Cytochrome P-450 (P-450) levels were inhibited more than 50% at 7 days following a single injection of PT mixed with either vaccine. When combined with DT vaccine, 125 ng of PT was required to produce this effect, while as little as 16 ng of PT combined with APDT vaccine inhibited P-450 levels. The inhibition of P-450 levels is similar to that observed after a single injection of diphtheria and tetanus toxoids and pertussis vaccine adsorbed (DTP). Alterations of P-450 levels were accompanied by increased activities of quinone reductase but not with changes in plasma interleukin-6 or tumor necrosis factor levels. Other Bordetella pertussis virulence factors, such as filamentous hemagglutinin, fimbriae and pertactin, were also tested but had no significant effect on hepatic drug metabolism. Endotoxin or preparations containing endotoxin caused alterations in hepatic drug metabolism within 24 h, concomitant with increased interleukin-6 and tumor necrosis factor levels, but these effects had resolved by 1 week. DTP vaccine and preparations containing PT caused a marked induction of gamma interferon coincident with the maximal inhibition of P-450 levels. This effect was not present with DT or APDT vaccine alone, nor with endotoxin or any combination of factors that did not contain PT. These results demonstrate that PT is a necessary component for the sustained effects of DTP vaccine on hepatic drug metabolism and suggest a role for gamma interferon in this process.

Animals↗
PubMed1993

Propofol at a subanesthetic dose may have abuse potential in healthy volunteers.

We conducted a study in which the rewarding effects of propofol were assessed in humans, using a discrete-trials choice procedure. Normal healthy volunteers (n = 12) were exposed in a blind fashion to acute bolus injections of 0.6 mg/kg of propofol twice and to a similar volume of Intralipid twice. Then, for the next three sessions, subjects chose which drug (identified by a color code) they wished to receive. We defined propofol choosers if individuals chose propofol two or three times, and nonchoosers if they chose propofol once or not at all. By using a chi 2 goodness-of-fit test of a random choice model, the choice distribution differed significantly from a random choice distribution (P < 0.005). Six subjects were choosers: four subjects chose propofol on all three choice occasions and two subjects chose the drug on 2/3 occasions (referred to hereafter as propofol choosers). Six subjects were nonchoosers: five subjects chose Intralipid on all three choice occasions, and one subject chose Intralipid twice (referred to hereafter as propofol nonchoosers). During sampling sessions, propofol choosers reported pleasant acute effects and no unpleasant residual effects, whereas propofol nonchoosers reported either unpleasant acute subjective effects and/or residual effects from propofol. We conclude that 1) propofol may be rewarding (reinforcing) in some individuals without a history of drug abuse, and 2) further abuse liability testing is needed with this drug.

Adult↗
PubMed1992

The use of transcranial ultrasonography to predict stroke in sickle cell disease.

BACKGROUND: Stroke, especially cerebral infarction, is a major cause of morbidity and mortality in children with sickle cell disease. Primary prevention of stroke by transfusion therapy may be feasible if there is a way to identify the patients at greatest risk. Transcranial Doppler ultrasonography can measure flow velocity in the large intracranial arteries. The narrowing of these arteries, which leads to cerebral infarction, is characterized by an increased velocity of flow. METHODS: Using transcranial Doppler ultrasonography, we prospectively measured the velocity of cerebral blood flow in children and young adults being followed because of sickle cell disease. The results were classified as either normal or abnormal on the basis of the highest velocity of flow in the middle cerebral artery. Abnormal velocity was defined as a flow greater than or equal to 170 cm per second, a definition determined by post hoc analysis to maximize the predictive success of the test. The end point was a clinically apparent first cerebral infarction. RESULTS: Two hundred eighty-three transcranial ultrasound examinations were performed in 190 patients with sickle cell disease (age at entry, 3 to 18 years). After an average follow-up of 29 months, cerebral infarction was diagnosed in seven patients. In 23 patients the results of the ultrasound examinations were abnormal, and in 167 patients they were normal. The clinical and hematologic characteristics of the two groups were similar, but six of the seven strokes occurred among the 23 patients with abnormal ultrasound results (P less than 0.00001 by Fisher's exact test). In this group, the relative risk of stroke was 44 (95 percent confidence interval, 5.5 to 346). CONCLUSIONS: Transcranial ultrasonography can identify the children with sickle cell disease who are at highest risk for cerebral infarction. Periodic ultrasound examinations and the selective use of transfusion therapy could make the primary prevention of stroke an achievable goal.

Adolescent↗
PubMed1992

Transperineal percutaneous iridium-192 interstitial template implant of the prostate: results and complications in 321 patients.

A total of 321 patients with localized adenocarcinoma of the prostate treated by modified pelvic lymphadenectomy, Iridium-192 implant, and external beam iridium radiation were retrospectively reviewed. Analysis covered 8 years between 1981 and 1989 with a median population age of 72 (range 42 through 82 years). Disease-free survival for the entire group is 69% at 5 years with a median follow-up of 34 months (range 1.5 months to 98.5 months). As expected, both bulkier disease and positive nodal status adversely affected 5-year disease-free survival (p = 0.0001 for both). For tumors stage T1b (A2), T2a (B1), T2b (B2), T3 (C) the disease-free survival is 89.5%, 89.9%, 64.7%, and 48.8%, respectively; for NO disease 5-year disease-free survival is 76.5% versus N1/N2 disease with 5-year disease-free survival of 33.2%. Local control was excellent except for bulkier disease (p = 0.009). Tumors T1b, T2a, T2b, and T3 have 60-month local control rates of 95%, 93%, 83.6%, and 73.1%, respectively. Histologic grade also affected disease-free survival and local control with grade 1, grade 2, grade 3 showing 81.2%, 65.7%, and 45.1% disease-free survival at 5 years; and 93.6%, 82.2%, and 72.4% local control at 5 years. Estimates obtained using Kaplan-Meier method. Radiation induced morbidity was analyzed separately for all patients, there were 41 patients (13% of total) with 54 documented complications. There were no Grade 4 or 5 complications as per RTOG categories. Only 3 cases showed grade 3 complications (1%) and 51 cases showed grade 2 complications (15.9%). Grade 1 complications were not recorded. Of the grade 2 and grade 3 complications 30 were GU and 22 were rectal. The morbidity associated with combined interstitial implantation by transperineal percutaneous template and external beam iridium radiation for the localized prostate cancer is minimal with excellent local control and disease-free survival.

Adenocarcinoma↗
PubMed1992

Role of endotoxin in alterations of hepatic drug metabolism by diphtheria and tetanus toxoids and pertussis vaccine adsorbed.

Administration of diphtheria and tetanus toxoids and pertussis vaccine adsorbed (DTP vaccine) or endotoxin (LPS) resulted in marked alterations in hepatic drug-metabolizing enzymes in endotoxin-responsive (R) and non-endotoxin-responsive (NR) mice. A single human dose (0.5 ml) of DTP vaccine increased hexobarbital-induced sleep times to 1.6- to 1.8-fold above those of controls in both strains of mice. This effect persisted for 7 days. In contrast, Bordetella pertussis LPS-treated mice showed an increase at 1 day (3.0-fold for R mice and 1.5-fold for NR mice), which returned to control levels by day 7. Furthermore, cytochrome P-450 levels were decreased 30 to 40% 24 h after DTP vaccine administration in both R and NR mice, while after LPS administration they were decreased 30% in R mice and less than 10% in NR mice. Both spleen and liver weights of R and NR mice were increased 7 to 14 days following DTP vaccine administration. However, LPS treatment had no apparent effect on liver weights, and spleen weights of R mice were elevated from days 3 to 7. Histopathologic tissue examination showed random, multifocal inflammation with hepatocyte necrosis after DTP vaccine administration to both R and NR mice and an absence of lesions in LPS-treated mice. Premixing LPS with polymyxin eliminated the increased sleep times, but premixing DTP vaccine with polymyxin did not affect the increased sleep times. Levels of tumor necrosis factor and interleukin-6 in plasma of R mice were markedly increased after DTP and LPS treatment, while NR mice had reduced increases. These results suggest that LPS contributes to the alterations in R and NR mice seen within the first 24 h of vaccine administration but that it is not likely to contribute to the effects observed at later time points.

Animals↗
PubMed1992

Vasopressor therapy for hypotension during epidural anesthesia for cesarean section: effects on maternal and fetal flow velocity ratios.

The purpose of this study was to identify the influence of hypotension as a result of epidural anesthesia and of its treatment with either ephedrine or methoxamine on uteroplacental and umbilical flow velocity ratios and fetal acid-base status. Fifty healthy women with an uncomplicated full-term pregnancy were studied during elective cesarean section under epidural anesthesia. A method of continuously recording flow velocity waveforms was used that allowed the identification of simultaneous values of maternal and fetal Doppler indices related to events during the induction of anesthesia. In 15 patients in whom arterial blood pressure did not decrease, the uteroplacental pulsatility index (UtPI) did not change, but the umbilical pulsatility index (UmPI) decreased from a mean (95% confidence interval) of 0.98 (0.88-1.09) to 0.91 (0.82-0.99) (P less than 0.05). In 32 patients who experienced hypotension of at least 15%, the UtPI increased from 0.82 (0.76-0.89) to 1.04 (0.92-1.17) (P less than 0.01). Treatment with ephedrine had no influence on either the UtPI or UmPI, but treatment with methoxamine resulted in brief increases in the UtPI of 0.47 (0.24-0.69) during the first 5 min after its administration; the increases were brief and resolved within 2 min. The choice of vasopressor drug had no influence on the UtPI recorded just before surgery commenced (final UtPI), but those patients who experienced hypotension had significantly larger final UtPIs (1.02 (0.91-1.10)) than those who never became hypotensive (0.86 (0.72-0.99)), and this was associated with significantly increased placental hydrogen ion gradients. The choice of vasopressor drug appears to be of minor importance compared with the avoidance of hypotension.

Adult↗
PubMed1991

Glycero-3-phosphate is a precursor of glucose but not of glycero-3-phosphocholine in rat liver.

The previous claims by others of a novel choline transfer reaction involving CDP-choline and leading to the conversion of [U-14C]glycero-3-phosphate to glycero-3-phosphocholine in liver sub-cellular fractions could not be confirmed. Apparent labelling of glycero-3-phosphocholine, isolated by paper chromatography, was, in fact, explained by contamination by other radioactive metabolites, especially D-glucose. A synergistic effect on gluconeogenesis from [U-14C]glycero-3-phosphate was obtained by incubating well-washed mitochondria with washed microsomes.

Animals↗
PubMed1991

Rat liver and lung mitochondria do not incorporate radioactivity from glycerol-3-phosphate or CDP-choline into glycero-3-phosphocholine.

The proposed formation of glycero-3-phosphocholine (GPC) from glycerol-3-phosphate (GP) and CDP-choline catalysed by the enzyme GPC-synthetase has been examined in liver and lung subcellular fractions. Previous observations on the incorporation of radioactive GP into the GPC-spot on paper chromatograms have been interpreted as evidence for the GPC-dependent synthesis of phosphatidylcholine. Although we could reproduce this incorporation of GP, we could not detect any incorporation of radioactive CDP-choline into the GPC-spot using the same paper chromatographic system. TLC separation of the substrate and products showed no detectable formation of GPC with either radioactive substrate. These results strongly suggest that the previously reported formation of GPC in liver and lung was due to an inaccurate identification of the true radioactive products. We demonstrate that the major radioactive product formed in liver mitochondria is glucose. A small amount of radioactive glycerol was also detected. Lung mitochondria incorporate radioactive GP into glycerol and into another unidentified compound or compounds. It is concluded that the occurrence of the GPC dependent formation of phosphatidylcholine is unlikely.

Animals↗
PubMed1991

Vaccine-induced alterations in hepatic drug metabolism.

Administration of Diphtheria and Tetanus Toxoids and Pertussis Vaccine Adsorbed (DTP) vaccine to mice causes dose- and time-dependent alterations in hepatic drug metabolism as determined by hexobarbital-induced sleep time and several direct measurements of soluble and microsomal enzyme activities. Vaccines containing only tetanus and/or diphtheria toxoids did not alter hepatic drug metabolism, implicating the pertussis component as the cause of the observed changes. Other pyrogenic whole cell vaccines such as typhoid and cholera also had no effect on drug metabolizing capacity. However, polyriboinosinic polyribocytidylic acid (poly I:C), a compound thought to exert its effects through the induction of interferon, induced changes comparable to those seen with DTP vaccine. The similarities in the effects following administration of DTP vaccine and poly I:C suggest that vaccine-induced alterations of drug metabolism may be mediated by immunomodulatory agents such as interferons and interleukins. Studies with purified cytokines are planned to address this question.

Alanine Transaminase↗