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Biomedical subjects

J A Clark

Publications and source records attributed to J A Clark.

At least 127 records · Page 7Linked to original sources
PubMed1986

Integrated stereotaxic imaging with CT, MR imaging, and digital subtraction angiography.

A stereotaxic frame, compatible with digital subtraction angiography, computed tomography, and magnetic resonance imaging, is described along with a set of software programs that run in an independent imaging computer system, as well as in the computers associated with each modality. Plexiglas plates fastened to the sides of the frame contain fiducial markers that can be recognized in the images and from which the section position and in-plane coordinates of any point in the image relative to the frame may be determined. Coordinate measurements of isolated point targets may be made to an accuracy of better than +/- 1 mm within a 15-cm field of view in the plane of the section or projection on all modalities. The stereotaxic system is of sufficiently high accuracy to be used on a routine clinical basis with one or more of the above modalities.

Cerebral Angiography↗
PubMed1985

Personality and psychophysiological variables in abusive, neglectful, and low-income control mothers.

This study was designed to systematically investigate personality, psychophysiological, and cognitive appraisal variables in three groups of mothers, i.e., abusive (N = 14), neglectful (N = 13), and low-income control (N = 15). All subjects completed a Mini-Mult, the Repression-Sensitization Scale, the Group Embedded Figures Test, the Multiple Affect Adjective Checklist, and the Socialization scale of the California Psychological Inventory. They listened to an audiotape sequence of white noise, tone, and infant's cry sounds while cardiovascular and skin resistance measures were recorded. The mothers also rated six dimensions of the infant's cry on a semantic differential. The three groups of mothers differed on a variety of personality variables, e.g., on F, Depression (D), Psychopathic Deviate (Pd), Psychasthenia (Pt), and Schizophrenia (Sc) from the Mini-Mult, on their cognitive appraisal of the infant's cry, and on skin resistance measures. A combination of personality, psychophysiological, and cry rating variables was entered in a discriminant analysis that was successful in discriminating 80% of the subjects. The two significant discriminant functions were defined primarily by the Pd scale and a cognitive appraisal measure.

Acoustic Stimulation↗
PubMed1984

Pressure therapy in the treatment of post-burn hypertrophic scar--a critical look into its usefulness and fallacies by pressure monitoring.

Pressure therapy is generally accepted as the best noninvasive means of preventing and controlling hypertrophic scarring after burn injury. Most studies in the past have failed to correlate clinical response with magnitude of the garment-scar interface pressure. This study looked critically at our usual techniques of pressure therapy using pressure 'sensors' manufactured locally and based on electro-pneumatic principles. Many pitfalls, such as large variations of pressure at different geometric sites on the body, elastic deterioration in garments, problems of garment manufacture, and the unfavourable properties of the Lycra garments, were observed. Recommendations on pressure treatment were made based on our experiences, to improve the present technique of pressure therapy. These included the standardization of measurement techniques and garment tailoring, the regular checking of pressure at the garment-scar interface using pressure transducers, the appropriate garment adjustments, a strict regimen for garment wearing, and the intelligent use of pressure-padding and reinforcement. Areas of further research are also discussed.

Burns↗
PubMed1984

Transitional object attachments in early childhood and personality characteristics in later life.

The present study empirically assessed aspects of transitional object attachments formed in early childhood and their relationship to personality characteristics in later life. Subjects were college students enrolled in introductory psychology courses. They were assigned to either a transitional object group or a no transitional object group based on self- and parental reports obtained from a detailed questionnaire focusing on early object attachments. Stringent criteria of inanimate object attachments were used in selecting subjects. Subjects selected for the study were administered the Sixteen Personality Factor Questionnaire. Significant personality differences were found between the groups. These preliminary objective findings were discussed in terms of the role of concrete object attachments in early childhood and areas for further research.

Adolescent↗
PubMed1983

Selective IgA deficiency in blood donors.

The frequency of selective IgA deficiency was determined in a healthy population of 6,240 blood donors. Screening for IgA deficiency was performed by double-diffusion analysis in agarose gel. Confirmation testing was performed with the more sensitive passive hemagglutination inhibition assay. Prevalence of IgA deficiency, characterized by a serum level of below 50 mg/L, was 0.30% (1 in 328), which is the highest prevalence of selective IgA deficiency reported in a healthy population. Antibodies to IgA were detected in sera of 36.8% of the blood donors with selective IgA deficiency, which also is the highest prevalence of anti-IgA antibodies reported in any previous study. The literature on IgA deficiency in healthy populations is reviewed. Current concepts in treatment of IgA-deficient patients requiring blood products are described.

Adolescent↗
PubMed1982

Altered activation of rat hepatic cyclic AMP-dependent protein kinases with increasing age.

The activity ratio of hepatic cyclic AMP-dependent protein kinase has been found to change with increasing age in male, Long-Evans rats. In rats 35 days old (135 g), the activity ratio (cyclic AMP-dependent protein kinase activity measured in the absence and presence of exogenous cyclic AMP) was 0.76, it increased to 0.92 in rats 75 days old (315 g) and to 0.98 in rats 305 days old (646 g). This change in the activity ratio seems to correlate with the ability of aging animals to respond to a stimulus, and may be a primary mechanism in the biochemistry of aging.

Aging↗
PubMed1982

Characterization of indicator bacteria in municipal raw water, drinking water, and new main water samples.

Municipal water samples were analyzed by membrane filter (MF) and presence-absence (P-A) tests for pollution indicator bacteria. In four years, 11 514 bacterial cultures were isolated from either raw water, drinking water, or new main water samples submitted to three environmental laboratories. The bacterial species occurring most often in all types of water samples were Escherichia coli (11.6-39.7%), Enterobacter aerogenes (18.1-26.3%), Aeromonas hydrophila (8.8-17.0%), Klebsiella pneumoniae (7.7-10.3%), and Citrobacter freundii (5.9-22.7%). A lactose - lauryl tryptose - tryptone broth was examined as an alternative medium to modified MacConkey broth in the presumptive portion of the P-A test. The intensity of acid and gas production in presumptive positive P-A bottles was compared with the types and frequencies of indicator bacteria shown by confirmatory tests. The results of detecting indicator bacteria following the analysis of 53 130 samples over a 2-year period were arranged by water source (well, lake, river, mixed) and water type (raw or drinking) to determine the influence of these parameters on the recovery of indicator bacteria. A further subdivision of the sample types into raw surface, raw ground, in-plant, plant discharge, reservoir, and distribution samples demonstrated the effect of water treatment practices.

Aeromonas↗
PubMed1981

Sensible heat transfer from the fowl: boundary-layer resistance of a model fowl.

1. The sensible heat transfer from a physical model of an adult fowl was investigated for the range of air speeds encountered in poultry houses in the United Kingdom, 0.09 to 2.7 m/s, equivalent to Reynolds numbers (Re) from 10(3) to 3 + 10(4). The Grashof number (Gr) range studied was from 6 + 10(6) to 10(7). 2. The pooled results were analysed to give a relationship between the Nusselt number (Nu) and Re in the mixed convective regime of : Nu = 2 + 0.79 Re0 48 A combination of Nu, Re and Gr did not produce a better fit to the results. 3. Enhancement of heat transfer observed when Re was close to 10(3) was probably caused by an interaction between the forced and natural air currents.

Animals↗
PubMed1981

Sensible heat transfer from the fowl: radiative and convective heat losses from a flock of broiler chickens.

1. Measurements of the micro-climate within a poultry house and physical models of heat loss produced estimates of the sensible heat losses from broilers. The partition between radiative and convective heat losses changed with age and bird activity. 2. The birds spent approximately 67% of ;their time in a cluster, in which their sensible heat losses were between 30 and 60% of those of an individual bird. 3. body plus plumage resistance was constant at 0.09 m2K/W up to 30 d and increased linearly to 0.40 m2K/W at 54 d.

Animals↗
PubMed1980

Disseminated intravascular coagulation following cranial trauma. Case report.

Cranial and spinal trauma resulted in disseminated intravascular coagulation (DIC) in a 78-year-old man, causing widespread bleeding and incoagulable blood. Traumatized brain tissue was found in the lumina of dural venous sinuses. The mechanisms of DIC are reviewed. It is suggested that intravascular release of potent cerebral thromboplastin contributed to the severity of DIC in this patient, by causing activation of the extrinsic clotting system. Intrasinus brain tissue in cases of human trauma has not previously been reported.

Aged↗
PubMed1979

Substituted 3-amino-1,1-diaryl-2-propanols as potential antidepressant agents.

Following the discovery that 3-(dimethylamino)-1,1-diphenyl-2-propanol hydrobromide (1) possesses potent reserpine-prevention activity in mice, a series of analogues of 1 was synthesized and evaluated as potential antidepressant agents. Several routes to analogues of 1 were evaluated, the most generally applicable of which was the regiospecific ring opening of a suitably functionalized 1,1-diaryl-2,3-epoxypropane (obtained in three stages from the corresponding benzophenone) with the appropriate amine. The more interesting compounds of the series were evaluated for their propensity to cause undesirable peripheral anticholinergic effects, all compounds tested being markedly less active than imipramine on this parameter. On the basis of its good activity in biochemical and pharmacological animal models of depression, together with its relative lack of anticholinergic side effects, 1-(3-chlorophenyl)-3-(dimethylamino)-1-phenyl-2-propanol hydrochloride (20, BRL 14342) was chosen for further evaluation.

Animals↗