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Biomedical subjects

C Clark

Publications and source records attributed to C Clark.

At least 235 records · Page 13Linked to original sources
PubMed1984

Intrauterine hypercarbia and lamb lung surfactant synthesis.

Prenatal asphyxia resulting in hypoxia, hypercarbia and amniotic fluid aspiration reduces the synthesis of the pulmonary surfactant. Using 135-day fetal lambs we studied the in utero effects of hypercarbic acidosis alone on fetal breathing activity, excised lung pressure-volume relationships and lamellar body (LB) surfactant disaturated phosphatidylcholine (DSPC) pool size and specific activity for [14C]palmitate. Fetal PaCO2 levels greater than 125 mm Hg for 30 min were associated with pH values less than 7.0 and very vigorous breathing activity. Analysis 22 h after the period of hypercarbic acidosis demonstrated no differences in pressure-volume relationships or the quantity of lamellar body surfactant DSPC. The specific activity of lamellar body DSPC also was not different although total label (dpm) per gram dry weight was higher and label was detected in the lavage fluid earlier in the acidotic lambs than controls. We conclude from these data that hypercarbic acidosis does not influence the synthesis or function of the pulmonary surfactant as assessed in this system. From these results and prior work from our laboratory we can infer that hypoxia remains the most probable cause for reduced surfactant synthesis in the asphyxiated fetus.

Acidosis, Respiratory↗
PubMed1983

Hypothalamic adrenergic activity precedes the preovulatory luteinizing hormone surge in the rat.

A preovulatory surge of luteinizing hormone (LH) is stimulated by an increase in plasma oestrogen (E2) and a proestrous neural signal which occurs during the 'critical period' (CP). Adrenergic activity during the CP in brain areas concerned with LH release and receiving adrenergic nerve terminals, increased in the arcuate nucleus-median eminence area (AN-ME) during the CP (14.30-16.30 h), but not in the adjacent perifornical area. Pentobarbital injected prior to the CP inhibited the effect as did ovariectomy, while E2 replacement restored it. Thus increased adrenergic activity in the AN-ME may represent the neural signal that triggers the preovulatory LH surge [5].

Adrenergic Fibers↗
PubMed1983

Employee rubella screening programs in Arizona hospitals.

One year after voluntary guidelines on rubella screening of hospital employees were issued by the Arizona Department of Health, a survey of 68 members of the Arizona Hospital Association was conducted, with an 81% response. Some form of employee rubella screening was present in only 49% of responding hospitals. Of the screening hospitals, 70% of programs had a mandatory aspect for selected employees. Administrative logistics, cost, problems encountered, and the quality and coverage of the program varied substantially among the different hospitals. Fewer than half of the screening hospitals had programs for physicians, students, or volunteers. Verbal histories of immunization or serological tests, although notoriously unreliable, were accepted by 14% of the screening hospitals. Half of the nonscreening hospitals plan to implement programs in the future. Reasons given for not establishing rubella screening programs include cost, no pediatric or obstetric service, liability issues, high turnover, and no previous case of rubella in an employee. Three hospitals (all screening) reported they had had a case of rubella in an employee. The data suggest slow partial compliance with recommendations for rubella screening in hospitals.

Adolescent↗
PubMed1983

Mother-infant interactions of teen-age mothers as measured at six months in a natural setting.

Mother-infant interaction of 14 teen-age mothers and their six-month-old infants was observed in the home and compared with that of 12 women 20 years or older and their infants. A further group was designated a "noncontact" group and was seen only at the beginning and end of the first year and was a control for research intervention or experimenter effects. Teen-agers showed few significant differences from older mothers in their mothering skills as measured by simple frequency distributions of individual behaviors and social interaction. Transitional probabilities and flow of interaction matrixes also revealed few significant differences. Like previous studies, the present study found that teen-age mothers showed high warmth and physical interaction but low verbal interaction with their infants. Support of the mothers through experience in the observational sessions may have influenced the results. The possibility is noted of differences in patterns of mothering as the infant develops.

Adolescent↗
PubMed1983

Cluster analysis of the WAIS on brain-damaged patients.

In recognition of increased usage of cluster analytic techniques, the current study attempted to examine sampling bounds for tests and subjects on one cluster-analytic procedure. Specifically, the WAIS subtest scores from a heterogeneous group of subjects with CNS involvement were first, factor analyzed and then clustered by means of Ward's hierarchical procedure. This methodology had been previously applied to two different samples of aphasics and aphasia batteries. In both these aphasic studies, an underlying severity dimension of language dysfunction was found. In contrast, in the current study, salient feature groups were found. Moreover, these groups were distributed in a sequential or hierarchical model in terms of specific cognitive deficits. From these data, it is argued that two major parameters in determining the resulting cluster structures are the homogeneity/heterogeneity of the sample and test battery employed. Although such a statement is obvious, the theoretical ramifications are large, in that the cluster structure may be a function of test weighting or sample diversity, not the phenomenon of interest. However, the cluster structures found in the current study were consistent with historical models of cognitive dysfunction and also lend support to hierarchical models of sequential cognitive impairment. These findings are discussed in terms of their clinical and experimental ramifications with respect to grouping subjects in terms of WAIS profiles.

Adult↗
PubMed1983

An application of the background interference procedure to the Benton Visual Retention Test.

This study involved applying Canter's Background Interference Procedure to the Benton Visual Retention Test. In a heterogeneous sample of psychiatric and brain-damaged patients, it was found that brain-damaged patients reproduced fewer designs and made more errors in reproducing those designs than did psychiatric patients. Right-hemisphere and diffusely brain-damaged patients reproduced fewer designs correctly and made more errors than did left-hemisphere damaged patients. This pattern was maintained when the effects of level of intellectual functioning and age were statistically controlled. These results suggest that the Background Interference Procedure in conjunction with the Benton Visual Retention Test may make a contribution to the assessment of brain-injured patients.

Adult↗
PubMed1983

Teenage pregnancy: family syndrome?

A short term, longitudinal study was conducted in order to explore selected psychosocial characteristics of fourteen teenagers aged sixteen years or younger who became mothers, the subsequent interaction of the mother-infant dyads, and the development and attachment of their infants at twelve months. The sample was matched for socioeconomic and marital status, intellectual ability and ethnicity with non-pregnant teenagers and pregnant women twenty years or older. The subjects were given a psychological and social history test battery. The groups did not differ significantly on the personality tests. The pregnant women reported a significantly poorer daughter-father relationship than the nonpregnant controls. In a high proportion of cases it was found that their fathers were absent or ineffectual and the homes mother-ridden. The interview data suggest that a large number of the pregnancies were psychologically motivated.

Adolescent↗
PubMed1982

Shortening the Speech Sounds Perception Test.

Statistical means of shortening the Speech Sounds Perception Test were examined. Stepwise multiple regression analyses indicated that a 30-item version correlated quite highly with the 60-item version. Group means for representative clinical groups were presented, but no strong differences emerged using either version. Inclusion of length of stay and number of previous admissions as covariates did little to enhance the predictive validity of either form. Finally, the correlation of the 30-item test with demographic variables showed that age correlated most, followed by occupational status. these results were interpreted as indicating that the 30-item version could be used while maintaining the clinical utility of this test.

Adult↗
PubMed1982

Delayed hypersensitivity responses to human IgG and methylated bovine serum albumin are regulated by different mechanisms.

We found marked differences in in vitro and in vivo delayed hypersensitivity (DH) responses to human IgG (human gamma-globulin, HGG) and methylated bovine serum albumin (MeBSA). Lymph node cells (LNC) from cyclophosphamide (CY) pretreated, antigen-adjuvant immunized mice exhibited increased HGG-induced and decreased MeBSA-induced proliferative responses in vitro compared with LNC from similarly immunized but non-CY-pretreated animals. These effects were antigen-specific. Further, treatment of CY-HGG-adjuvant immunized mice with aqueous (aq) HGG either before or after immunization markedly suppressed HGG-specific in vitro proliferation and in vivo DH responses. Therefore, induction of suppression by aqHGG did not appear to depend on CY-sensitive cells either as a possible source of suppressor cell precursors or as participants in the regulatory events. In contrast, in vivo DH reactivity to MeBSA was unaffected by administration of aqMeBSA either before or after mice were immunized with CY-MeBSA-adjuvant. Our results suggest that DH responses to HGG and MeBSA are regulated by distinct mechanisms which influence the induction and the development of sensitivity.

Adjuvants, Immunologic↗
PubMed1981

Severity of impairment or specific types of aphasia: an empirical investigation.

This study examined empirical means of clustering aphasic patients into relatively homogenous and identifiable groups. The method included: (1) examining the intercorrelations of the subtests of the Neurosensory Comprehensive Examination for Aphasia by the means of factor analysis; (2) allowing the subjects to group themselves in homogenous subgroups by means of hierarchical cluster analysis; and (3) comparing the profiles of these groups on the derived dimensions. Four factors accounting for 79.3% of their total test variance were derived which reflected attention/memory; reading ability; verbal-naming ability; and elementary writing skills. With five groups the hierarchical grouping analysis indicated that only 21.5% of the total variability could be ascribed to within group variability. An analysis of variance of the four factor scores found that 66%, 93%, 81% and 79% of the between group variance of each of the respective factors was associated with group membership and the accuracy of membership prediction was 94.1%. Four groups appeared to be distributed on the basis of a severity model of impairment. One group representing 6.3% of the total sample demonstrated a pattern of specific impairment involving a mild level of impairment on attention/memory tasks, a moderate level of impairment on verbal naming tasks and writing skills, and a profound level of impairment on measures of reading skills. The high inter-factor correlations indicated the general nature of language functioning. The results were discussed in terms of the concept of aphasia as a general cognitive deficit.

Aphasia↗
PubMed1981

Blood transfusion: a possible risk factor in retrolental fibroplasia.

The effect of blood transfusion on the occurrence of RLF was evaluated in 58 infants who weighed less than 1001 g at birth (Group I) and 70 oxygen treated infants of various birth weights (Group II). Although there was no significant difference between Group I infants with or without exchange transfusion as to birth weight, gestational age, duration of oxygen therapy, peak Pa02's, or multiple births, there was a significantly increased incidence of pre-retrolental fibroplasia in transfused over non-transfused Group II infants. When Group II infants were stratified for prematurity and oxygen duration, this difference persisted in those not already at risk for RLF. This increased incidence of retinopathy in transfused infants suggests that blood transfusion may be a risk factor in the pathogenesis of RLF.

Apnea↗