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Biomedical subjects

C Clark

Publications and source records attributed to C Clark.

At least 199 records · Page 11Linked to original sources
PubMed1989

Two-year follow-up study of coronary bypass surgery. Psychologic status, employment status, and quality of life.

This study is a prospective report of the cases of 135 patients who were slated for coronary artery bypass grafting and selected according to designated criteria. Patients received, in addition to an interview, a comprehensive cognitive, neuropsychologic, and personality assessment 2 weeks before operation and 3, 12, and 24 months after operation. Of the available sample, 82.3% completed the full study. There was no evidence of intellectual or neuropsychologic impairment after operation. Most patients returned to preoperative status 3 months after bypass grafting. Further improvement may continue 12 and 24 months after operation. The personality tests revealed that anticipation of the operation resulted in signs of emotional arousal and distress, which dissipated after a successful surgical outcome. Similarly, return to work and quality of life was enhanced. The current study represents the first systematic, longer-term follow-up of the psychologic and social consequences of coronary artery bypass grafting operations. The findings of this study are discussed within a model of social reconstitution after the successful resolution of a life-threatening medical condition.

Adult↗
PubMed1989

Progressive ankylosis (ank/ank) in mice: an animal model of spondyloarthropathy. III. Proliferative spleen cell response to T cell mitogens.

Murine progressive ankylosis is a spontaneous disorder of mice resulting from a homozygous recessive genetic defect (ank/ank) which produces an inflammatory arthritis of peripheral and axial joints eventually resulting in ankylosis of these joints. This disorder resembles the human spondyloarthropathies clinically, radiographically and histologically. Various studies in humans with spondyloarthropathies have described defects of cellular immunity but these results are conflicting. We measured the spleen cell response to mitogen in ank/ank mice and in normal littermates. The spleen cell response to the T cell mitogens phytohaemagglutinin and concanavalin A was decreased in ank/ank mice compared with their normal littermates. The response to the B cell mitogen lypopolysaccharide was normal in both ank/ank mice and normal littermates. Serum from ank/ank mice did not inhibit spleen cell responses to mitogen. Ank/ank spleen cells were not inhibitory of normal spleen cell responses to mitogens. Addition of irradiated normal spleen cells to ank/ank spleen cells did not restore the mitogen responses to normal. It is possible that the ank/ank gene results in the phenotypic expression of an abnormal or decreased cell product involved in T cell proliferation. Several recently described cytokines could be potential candidates for this product.

Animals↗
PubMed1988

Olfactory deficits in schizophrenia.

Olfactory discrimination was measured in patients with schizophrenia who were on neuroleptic medication and was compared with other psychiatric patients receiving neuroleptics and normal controls. The performance of the patients with schizophrenia was significantly lower than the psychiatric and normal controls. The latter two groups performed at equivalent levels. The findings are discussed with respect to olfactory deficits found in patients with cerebral lesions and with abnormalities of specific neurotransmitter systems.

Adolescent↗
PubMed1988

Giardia-bile salt interactions in vitro and in vivo.

Giardia lamblia predominantly colonizes the proximal small intestine where bile is plentiful. We have investigated interactions between bile and this parasite by (i) examining the specificity of the stimulatory effect of bile on parasite growth in vitro, (ii) studying the possible association between giardiasis and bile salt deconjugation in vivo, and (iii) quantifying bile salt uptake by Giardia and relating this to uptake by other microorganisms. Our findings indicate that the growth promoting effects of ox bile and pure bile salt (sodium glycocholate) are, as far as is known, specific for Giardia, since the growth of a related protozoon, Trichomonas vaginalis, and a variety of enteric bacteria was either unchanged or inhibited. We were unable to detect deconjugated ('free') bile salt in duodenal fluid from UK patients with giardiasis and found no evidence to suggest that Giardia deconjugated bile salts in vitro. However, Giardia avidly took up conjugated bile salt, apparently in a concentration-dependent manner and to a much greater degree than Trichomonas and enteric bacteria. Thus, bile specifically stimulates growth of Giardia, and bile salt is avidly consumed by the parasite. The mechanism by which bile stimulates parasite growth is unknown, but uptake of conjugated bile salt by Giardia could reduce intraluminal bile salt concentrations and possibly interfere with micellar solubilization of fat. This may contribute to the steatorrhoea which is well recognized in symptomatic patients with giardiasis.

Animals↗
PubMed1988

A genetic linkage study of a family with Norrie's disease.

A family having one member with Norrie's disease, X-linked retinal dysplasia associated with hearing loss and mental retardation, was studied using DNA markers. The DNA markers were used to try and confirm the diagnosis of Norrie's disease by detecting a deletion of the X chromosome. Linkage analysis using the polymorphic DNA markers was performed and this allowed more accurate determination of the carrier status of two sisters of the affected boy than by empiric risk calculation. The advantage of multiple polymorphic DNA markers for linkage analysis is illustrated.

Chromosome Mapping↗
PubMed1988

Reliability and construct validity of the six-block Tactual Performance Test in and adult sample.

The ten-block Tactual Performance Test (TPT-10) has been criticized as a clinical instrument due to the long administration time and accompanying psychological distress. The shorter children's six-block version (TPT-6) has been proposed as a potential substitute. The current study examined the internal consistency, the test/retest reliability and the construct validity of the TPT-6. The results indicate that the TPT-6 is a very reliable instrument and is similar to the TPT-10 in terms of construct validity. Most importantly, the actual administration time is approximately one third that of the TPT-10.

Brain Damage, Chronic↗
PubMed1988

Empirically derived MMPI profiles. Coronary bypass surgery.

A cluster analysis of eight clinical scales of the MMPI-168 was performed on data from 129 subjects awaiting coronary bypass surgery. Four abnormal profiles were derived and these profiles were consistent with clinical expectancy. The five empirically derived profiles were labeled as a) normal--that is, no elevated scales; b) marginal distress--elevated Hs; c) conversion V--elevated Hs and Hy; d) neurotic--elevated Hs, D, Hy, and Pt; and e) generalized distress--elevated D, Hy, Pd, Pa, Pt, and Sc. Subsequent postsurgical follow-ups were done at 3-, 12-, and 24-month intervals. These data suggest that the profiles retained their characteristic shape and were still statistically different from each other, but the overall elevation decreased significantly after successful surgical intervention. To externally validate these profiles, the five derived groups were compared in terms of Beck Depression scores and the State/Trait Anxiety Inventory. These results were consistent with the MMPI. These data are discussed in terms of developing models for assessing the interaction of personality and specific stressors.

Adult↗
PubMed1988

Proctitis and fatal septicemia caused by Plesiomonas shigelloides in a bisexual man.

A case of proctitis and fatal septicemia caused by Plesiomonas shigelloides in a 42-year-old bisexual male is reported. The medical history of the patient was significant for an aortic valve replacement 3 years before but was otherwise unremarkable. A serum specimen obtained at autopsy was negative for antibody to human immunodeficiency virus by Western blot (immunoblot) analysis. P. shigelloides isolated from blood was susceptible to all antibiotics tested, agglutinated in Shigella group D antiserum, possessed a greater than 100-megadalton plasmid, and was noninvasive in a HeLa cell invasion assay. The previous reports of Plesiomonas bacteremic infections are reviewed, and possible pathogenic mechanisms are discussed.

Adult↗
PubMed1987

Low-dose X-irradiation and 4-hydroperoxycyclophosphamide distinguishes three Lyt-1+ lymph node T-cell subtypes that respond to specific antigen in vitro.

We investigated whether preculture exposure to low-dose X-irradiation and culture treatment with 4-hydroperoxycyclophosphamide (4-HPCY), a synthetic derivative of cyclophosphamide (CY), might distinguish subtypes of thymic-dependent (T) lymphocytes that respond to specific antigen in vitro. Lymph node (LN) cells were obtained from mice pretreated with CY and immunized with aggregated (A) human IgG (HGG) in Freund's complete adjuvant (CFA), and proliferation was assessed by incorporation of tritiated thymidine. Primed LN cells were untreated or exposed to low-dose irradiation before being cultured in medium alone and in medium containing 4-HPCY. The results show that these agents (irradiation and 4-HPCY) distinguished, in a dose-dependent manner, subtypes of T-cells which contribute to the specific antigen-stimulated proliferative response in vitro. For LN T-cells and LN Lyt-1+ T-cells, 20-25 rads and 1.0 microM 4-HPCY inactivated non-overlapping cell subtypes that respectively accounted for 26% and 28% of the response to HGG. The remaining 46% of HGG-responding cells were not affected by either agent. Although similar cell subtypes were discerned in unseparated LN cells, it required use of higher agent-doses. Cell cycle analysis revealed that treatment with irradiation, 4-HPCY, and the combination (both agents) caused S-phase arrest of 29%, 30%, and 55% of HGG-responding cells, respectively. Thus, identification of these cell subtypes could not be attributed to agent-mediated inactivation of HGG-responding cells that might be in exclusively different phases of the cell cycle.

Animals↗
PubMed1987

Controlling for cerebral atrophy in positron emission tomography data.

This article outlines a simple method for estimating the degree of cerebral atrophy and subsequent experimental control for the effects of cerebral atrophy on regional metabolic values measured with positron emission tomography. It is suggested that rather than correcting derived values for atrophy, less potential error is introduced by experimentally controlling for regional atrophy when possible. By treating the derived metabolic rates and the measure of atrophy as two separate variables, it is also possible to establish whether there actually is a demonstrable relationship between the two measures.

Adolescent↗
PubMed1987

Treatment outcome of obstructive sleep apnea. Physiological and neuropsychological concomitants.

This study examines the cognitive and emotional changes associated with successful surgical treatment of patients with obstructive sleep apnea (OSA). By comparing the OSA patients with patients undergoing coronary artery bypass surgery before (2 weeks) and after (3 months) surgical intervention on a comprehensive psychological battery, it was determined that both groups exhibited anxiety and depression before surgery and these elevations (MMPI) were significantly lower after surgery. However, no differences were found between groups on any emotional or cognitive variable before or after surgical treatment.

Adult↗
PubMed1987

The combined use of positron emission tomography and DNA polymorphisms for preclinical detection of Huntington's disease.

Twenty-three persons at risk for Huntington's disease (HD) have been studied using a polymorphic human linked DNA marker (D4S10) and positron emission tomography (PET). We determined the likelihood of inheritance of the gene for HD in 13 persons, using DNA polymorphism studies. Of these, eight persons had a greater than 90% probability of being presymptomatic heterozygotes for HD. Three of these eight subjects had caudate glucose utilization detected by PET that was more than 2 standard deviations (SD) below the age-matched control mean. Measurement of caudate glucose utilization in the other five presumed presymptomatic heterozygotes revealed results between 1 and 2 SD below the mean. Five persons had a less than 10% likelihood of having inherited the abnormal gene for HD. Of these, four had normal rates of glucose utilization in the caudate nuclei. However, one individual with DNA results indicating a low risk of developing HD had abnormally low measures of caudate glucose utilization. This suggests that a recombination had occurred between the linked marker and the gene in this person. These studies suggest that PET studies of caudate glucose utilization may help to confirm results of DNA studies in some persons, and may provide an opportunity to detect when DNA results may be incorrect due to recombination.

Brain↗