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Biomedical subjects

C Clark

Publications and source records attributed to C Clark.

At least 19 recordsLinked to original sources
PubMed1979

The effect of topical crude coal tar treatment on unstimulated hairless hamster skin.

Topical treatment of hairless hamster skin with crude coal tar has been shown to induce epidermal thickening, an increased labelling index in the basal cell layer, an elevation in NADP-dependent glucose-6-phosphate dehydrogenase activity throughout the epidermis, an increased squame count, comedo formation, and atrophy of the sebaceous glands. Ultraviolet light fluorescence microscopy of sections of treated skin suggests that the hair follicle is an important route for skin penetration by coal tar.

Acne Vulgaris↗
PubMed1979

Characterization and quantitation of murine-delayed hypersensitivity responses elicted with particle-associated human gamma-globulin.

Parameters delineating the utilization of particle-associated human gamma-globulin to quantitate murine-delayed hypersensitivity (DHS) responses include: (1) the conditions used to prepare HGG-coated polystyrene latex particles; (2) the marked increase in sensitivity of detection of delayed immune responsiveness using particle-bound HGG; (3) a histologic analysis of the lesions induced by HGG-latex in DHS mice, and (4) the increased retention of particle-associated as opposed to soluble HGG at the site of challenge. The potential utilization of particle-bound antigens as a sensitive method of assessing the role of delayed-type responsiveness in tumor and transplantation immunity is discussed.

Animals↗
PubMed1979

Recovery of the gastric mucosa from bile-induced injury.

Bile salts are known to injure the gastric mucosa and may be involved in the pathogenesis of gastric stress ulceration, a feared sequela of shock. Although the induction of bile injury to the stomach has been extensively studied, recovery from such an injury has not. In the studies reported here the period after removal of bile was examined to see whether the mucosa could return to pre-bile-exposure status under various circumstances. Recovery from a bile salt-induced injury was studied in three mongrel dogs with Heidenhain pouches. Net acid back diffusion (NABD) was measured with a recirculating system incorporating a pH stat and was measured with a recirculating system incorporating a pH stat and autoburette, and transmucosal electrical potential difference (PD) was measured by usual methods. The effects of exposure to 5 mM taurodeoxycholate at pH 2 for 30 minutes were studied. This exposure increased net acid back diffusion from 23 +/- 5 to 184 +/- 16 micro Eq/10 min (P less than 0.01) and reduced PD from 56 +/- 2 to 18 +/- 2 mV (P less than 0.01). After injury the pouches were copiously irrigated with saline to remove bile, and then recovery was observed as the pouches were perfused with pH 1, 2, or 7 HCl solution made isotonic with NaCl. The recovery values were compared with the same dog's preinjury values at the same pH perfusion. The data showed that at pH 2 and pH 7, PD and NABD returned to preinjury levels within 90 minutes after bile injury. At pH 1, however, recovery did not occur. The pH dependence of recovery from bile-induced injury may have relevance to patients with episodic reflux of bile into the stomach.

Animals↗
PubMed1978

Niemann-Pick disease: prenatal diagnoses and studies of sphingomyelinase activities.

Five pregnancies were monitored for couples at-risk for having a child with some form of Niemann-Pick disease (NPD). Three of these were for the classic Type A form in which affected children usually have less than 1% of normal sphingomyelinase activity. Two of these pregnancies were terminated after the cultured amniotic-fluid cells were determined to have less than 1% of normal sphingomyelinase activity (0.4 and 0.6 nmole/mg protein/hr versus the control mean of 61.7). In the other pregnancy at risk for Type A NPD near normal activity was measured and it was continued to term. The two other pregnancies were monitored for couples in which severely affected children were found to have partially deficient sphingomyelinase activity (about 20% of normal) in cultured skin fibroblasts. Cultural amniotic-fluid cells from one of these pregnancies also had about 20% of control sphingomyelinase activity, but the woman underwent a spontaneous abortion soon after the cells were received and no studies on the fetus were done. The other sample was taken at the time of abortion for social reasons. In this case the cultured amniotic-fluid cells and cultured fetal skin fibroblasts gave normal sphingomyelinase activity. Enzymatic studies on tissues from the two fetuses predicted to be affected with Type A NPD confirmed the prenatal diagnosis. Studies of sphingomyelinase activity in the brains from these fetuses and from a child who died with Type A NPD indicated significant levels of activity when measured at pH 7.4 in the presence of magnesium. The higher level of the pH 7.4 sphingomyelinase activity in developing brain may indicate some important role in normal brain development.

Adult↗
PubMed1978

The measurement of histochemically-stained NADP-dependent isocitrate dehydrogenase in the sebaceous glands of hairless hamster.

The effect of substrate, co-factor and Nitroblue Tetrazolium concentration on the production of formazan by the action of NADP-dependent isocitrate dehydrogenase was studied in the sebaceous glands of the hairless hamster. The measurement (in average optical density units per unit area) of formazan in histochemically stained skin sections was carried out by television scanning microdensitometry (Quantimet 720D). Having established optimal conditions for this enzyme, a second study was carried out to determine the effect of different power objectives and wide-band wavelength light instead of white light on the average optical density per unit area, recorded by the instrument, of the formazan produced in a defined number of sebaceous glands in a single skin section. It was found that there was no difference in the average optical density per unit area recorded by the instrument at different power objectives and a peak value of average optical density per unit area could be obtained using a K4 or a K5 Balzer filter (550-650 nm).

Animals↗
PubMed1978

Hypoglycorrhachia and coxsackie B3 meningoencephalitis.

The case of a 3-week-old infant with Coxsackie B3 meningoencephalitis is discussed. Hypoglycorrhachia and neutrophils in the cerebrospinal fluid characterized the first ten days of her illness. Coxsackie B3 should be added to the list of enteroviruses that can cause hypoglycorrhachia during infections of the central nervous system in children.

Cerebrospinal Fluid↗
PubMed1978

Relation between pressure difference across the aortic valve and left ventricular outflow.

Equations are presented to relate left ventricular-aortic pressure difference and flow. The relative importance of fluid inertia and friction are evaluated and the errors introduced by the neglect of compliance are estimated. The equations are used to calculate pressure differences for both normal conditions and simulated aortic stenosis and to explain the timing of the reversal of the pressure difference.

Aortic Valve↗
PubMed1978

Synthetic substrate beta-glucosidase activity in leukocytes: a reproducible method for the identification of patients and carriers of Gaucher's disease.

A method is described for the identification of patients and carriers of Gaucher's disease, using leukocytes from a small volume of blood. The fluorogenic substrate, 4-methylumbelliferyl-beta-D-glucopyranoside, was assayed in the presence of pure sodium taurocholate (2.5 mg/ml) and Triton X-100 (2.0 mg/ml). Some commercial brands of pure sodium taurocholate were satisfactory for this purpose. The pH optimum for controls, Gaucher disease carriers and Gaucher disease patients was 5.4 using citrate-phosphate buffer. Although leukocytes prepared from only a small amount of blood (2-8 ml) are required, there is sufficient quantity for measuring other lysosomal enzymes as controls. Using this method, 12 patients with all types of Gaucher's disease and 12 obligate heterozygotes were identified. Carrier status was predicted in six other family members and ruled out in six others. Eight unaffected people married to Gaucher carriers or Gaucher patients were predicted to be non-carriers of Gaucher's disease, thereby ruling out children affected with Gaucher's disease in that mating.

Adult↗
PubMed1978

Suppression of prolactin by dopamine agonists in schizophrenics and controls.

Prolactin levels were determined in plasma samples obtained before and after administration of apomorphine or L-dopa to otherwise unmedicated chronic schizophrenic patients or control subjects. Basal prolactin levels did not differ in these two groups. Suppression of prolactin levels after each dopamine agonist was highly significant. Suppression in schizophrenics was slightly less than in controls following apomorphine and slightly greater following L-dopa. The authors discuss the implications of these findings as well as the limitations of the prolactin regulatory system as an index of dopamine agonist sensitivity.

Adult↗
PubMed1978

Cerebral cysticercosis.

Five patients with cerebral cysticercosis, two within the year preceding the date of this article, were seen at the New York Neurological Institute. The patients presented with mental changes, seizures, and symptoms of increased intracranial pressure, and had a history of having immigrated from an area endemic for cysticercosis. They were found to have parenchymal or intraventricular cysticercosis cysts. The interval from immigration to onset of symptoms was as long as 3 years. Plain radiograms of the skull and soft tissues, ventriculograms, and especially the CT scan, as well as the CSF examination, were useful in making the diagnosis. Surgical removal of an intraventricular cyst was curative in two patients and seizures were controlled with anticonvulsants in the other three.

Adult↗
PubMed1978

Genetic control of tolerance induction to human gamma-globulin in mice.

Susceptibility to tolerance induction with monomeric human gamma-globulin (HGG) was tested in different inbred strains of mice. The results indicated a differential tolerance susceptibility among the strains and that the basis for the variation is genetic in nature. By using a protocol that permits genetic analysis, F1, F2, and backcross generations of the parental strains SJL/J and C3H/Bi were examined. A multigenic control model by H-2-linked and non-H-2-linked genes showing Mendelian autosomal inheritance is proposed.

Animals↗