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Biomedical subjects

C Clark

Publications and source records attributed to C Clark.

At least 217 records · Page 12Linked to original sources
PubMed1987

Physicians, reformers and occupational disease: the discovery of radium poisoning.

Teenage girls and young women, whose job it was to apply luminous paint containing radium to watches during World War I, were among the first industrial radiation poisoning victims in the United States. This paper recounts both the story of how their afflictions became "recognized" occupational diseases and of the tangled web of governmental-industrial-academic collusion (largely based on industrial funding of research and experts) which delayed this recognition. It shows how these industrial-academic arrangements led to the establishment of the major academic training programs in occupational medical and industrial hygiene still in existence. Using historical sources, this study provides evidence of moral lapses by medical researchers, including directly lying to the victims, withholding data on the true extent of illness and radiation contamination and of distorting evidence. The pivotal role of the Consumers League and of Dr. Alice Hamilton in establishing the truth of the radium dial painting poisonings is discussed.

Adolescent↗
PubMed1987

The role of adjunctive Rodogyl therapy in the treatment of advanced periodontal disease. A longitudinal clinical and microbiologic study.

Several studies have indicated that the combination of metronidazole and spiramycin is synergistic against anaerobic bacteria and may be effective against oral infections. The present study sought to determine the efficacy and safety of a commercial preparation of these two antibiotics (Rodogyl) when used adjunctively in the treatment of advanced periodontal disease. In a double-blind parallel randomized trial, 56 patients (mean age = 44 years) with advanced periodontitis (50 of whom completed the study) were assigned to either the Rodogyl or placebo group. Both groups were thoroughly scaled and root planned for approximately 6 hours, with one group receiving Rodogyl for 2 weeks and the other a placebo. No other therapy was received during the study period. Two sites in each patient with probing depths of at least 7 mm were selected for study. Plaque level (P1I), gingival inflammation (GI), probing depth (PD), and attachment level (AL) were measured at baseline, 14 days, 1 month, and then at monthly intervals up to 6 months. Subgingival bacteria were monitored with dark-field microscopy. The development of resistant bacteria, as well as side effects to the medications, was also monitored. The Rodogyl group exhibited a greater gain in AL (0.67 mm) from the 2-month interval until the end of the study. Although this difference was statistically significant (P less than 0.05), it was not necessarily of biologic significance. There was a significantly greater decline in the proportion of spirochetes in the Rodogyl group at the 14-day interval, and this difference remained significant (P less than 0.05) at all study intervals. No difference in the proportion of motile organisms was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

DNA polymorphisms in and around the Apo-A1-CIII genes and genetic hyperlipidemias.

We have studied the frequency of DNA polymorphisms in and around the apolipoprotein A-1 (Apo-A1) and apolipoprotein CIII (Apo-CIII) gene loci in 53 persons of Caucasian descent with genetic hyperlipidemias. Three restriction-fragment-length polymorphisms (RFLPs) have previously been located 5' and 3' to the Apo-A1 gene and in the Apo-CIII gene and were detected after digestion with XmnI, PstI, and SstI, respectively, and hybridization with a 2.2-kb fragment of the Apo-A1 gene. These RFLPs are in linkage equilibrium. The rare variant sites for XmnI (X2) and SstI (S2) were more frequent in familial combined hyperlipidemia (FCH) than in controls and persons with other genetic hyperlipidemias. When considered as a haplotype, this difference was significant (P less than .03). The findings in this study suggest that the previously reported association between S2 and hypertriglyceridemia may be accounted for, in part, by inclusion of numerous patients with FCH. Our data provide further evidence that these RFLPs around and within the Apo-A1/Apo-CIII genes do not participate in unmasking clinical expression in persons with familial dysbetalipoproteinemia.

Adult↗
PubMed1986

Nonsurgical management of small and intracanalicular acoustic tumors.

It is generally accepted that the proper treatment for acoustic tumors is surgical removal. In fact, there is little, if any, reference to nonsurgical treatment of these tumors in the recent medical literature. We would like to report on the nonsurgical management of six patients with cerebellopontine angle tumors based upon CT examination. The diagnostic findings, follow-up data, and the rationale upon which the decision was made to treat the patients nonsurgically will be presented, as will a review of the pertinent literature.

Aged↗
PubMed1986

PET studies of cerebral glucose metabolism in idiopathic torticollis.

Regional cerebral glucose metabolism was studied in 16 patients with idiopathic torticollis, using positron emission tomography. Analysis of subcortical regions revealed no consistent focal abnormality of cerebral metabolic rate for glucose, but there was a bilateral breakdown of the normal relationships between the thalamus and basal ganglia. The findings suggest disruption of the pallidothalamic projections in this focal dystonia and may imply a disturbance of GABA.

Adult↗
PubMed1986

Positron emission tomography in the early diagnosis of Huntington's disease.

We studied 10 patients with early Huntington's disease and 7 normal age-matched controls with positron emission tomography (PET) using fluorodeoxyglucose. Subjects had little or no caudate nucleus atrophy and had not received any medications. The results demonstrated that hypometabolism of glucose preceded tissue loss. Furthermore, patients with minimal neurologic or psychiatric symptoms and no obvious CT changes may be differentiated from normal persons with high accuracy by PET. PET is helpful in the early diagnosis of Huntington's disease irrespective of the mode of presentation. PET may also be useful for preclinical detection and may supplement information from DNA studies.

Adolescent↗
PubMed1986

Improved health care delivery in an inner-city well-baby clinic run by general practitioners.

The delivery of health care has been improved in an inner-city well-baby clinic by staffing the clinic with members of a primary health care team and by offering a therapeutic service together with a preventive service. Over a three-year period attendance at the clinic has doubled and the uptake of immunization has increased. Of children registered with the practice supplying the health care team, 95% are up to date with diphtheria, tetanus and polio immunizations and 93% have been immunized against measles. It is suggested that general practitioners should have greater involvement in the running of well-baby clinics.

Child, Preschool↗
PubMed1985

The survival of very low-birth weight infants by level of hospital of birth: a population study of perinatal systems in four states.

This study estimates differentials in survival among very low-birth weight infants according to hospital of birth, and seeks to determine importance of birth at high-technology centers versus birth at other urban or rural hospitals. Data from four states for 1978 and 1979 were used to estimate survival curves for the first 24 hours of life by type of hospital at birth, birth weight, and race. Significant (p less than 0.0001) differences in survival by type of hospital for both races at birth weights of 1000 to 1500 gm were observed. Smaller disparities were seen at birth weights of 750 to 1000 gm. Differentials in survival by hospital setting emerged in the first few hours after birth, underscoring the effectiveness of neonatal intensive care units in reducing infant mortality and the importance of maternal transport. Differentials persisted throughout the neonatal and postneonatal periods, although differences were attenuated. Prenatal assessment and provider and institutional cooperation can contribute to lowered mortality for high-risk infants and mothers.

Black People↗
PubMed1985

Screening Rastafarian children for nutritional rickets.

We examined 42 Rastafarian children under 5 years of age who were registered with a single inner city general practice to determine the prevalence of nutritional rickets. Twenty children were receiving a strict vegan(I-tal) diet and were considered to be at high risk of developing rickets and were referred for biochemical and radiological investigation. Seven of 20 children investigated had rickets, giving an overall prevalence of 7/42. Treatment with oral cholecalciferol was successful in all seven children. Fourteen out of 18 children had evidence of iron deficiency, with low haemoglobin concentrations and hypochromic-microcytic blood films. Before this study Rastafarian children rarely attended the well baby clinic, received no vitamin supplements, and few had been immunised. They now regularly attend the clinic, receive vitamin and iron supplements, and all have completed primary immunisation.

Alkaline Phosphatase↗
PubMed1985

Evidence that X-irradiation and 4-hydroperoxycyclophosphamide affects different lymphocytes that respond to specific antigen in vitro.

The present study examined the effect of pulse treatment with the in vitro active synthetic derivative of cyclophosphamide (CY), 4-hydroperoxycyclophosphamide (4-HPCY), and exposure to X-irradiation on the in vitro Concanavalin A (ConA), lipopolysaccharide (LPS), and antigen-specific blastogenic responses of in vivo-primed lymph node cells. Primed lymph node cells from CY-pretreated, aggregated (A) human IgG-complete Freund's adjuvant (AHGG-CFA)-immunized mice were untreated, exposed to various doses of irradiation, or pulse treated with different concentrations of 4-HPCY before being cultured in medium alone or in medium containing HGG, ConA, or LPS. The results show that HGG-responding and LPS-responding cells exhibited similar dose-inactivation profiles following exposure to irradiation or pulse treatment with 4-HPCY. More than 75% of reactivity was eliminated by exposure to 100 rads or pulse treatment with 20 microM 4-HPCY. In contrast to preculture pulse treatment with 4-HPCY, however, when primed lymph node cells were cultured in medium containing 4-HPCY (culture treatment) LPS-responding cells were shown to be more sensitive to inactivation than HGG-responding cells. The data further show that the effect of low-dose irradiation and of culture treatment with 4-HPCY on the HGG-specific response of primed lymph node cells was additive, suggesting that these agents inactivate different cell subtypes that contribute to the HGG-specific response in vitro.

Animals↗
PubMed1985

A sleep-inducing peptide from Conus geographus venom.

A novel peptide toxin, which causes a sleep-like state upon intracerebral injection in mice, has been purified to homogeneity from the venom of the piscivorous marine snail Conus geographus L. It elicits no obvious effects when injected i.p. into either mice or fish. The purified toxin is a highly acidic heptadecapeptide with no cystine residues (Lys1, Arg1, Asx2, Ser1, Glx7-8, Gly1, Ile1, Leu2). This composition is in marked contrast to those of other conotoxins, which are basic and disulphide-bridged. The N-terminal residue is Gly and the COOH-terminal sequence is Ser-Asn-NH2.

Amino Acids↗
PubMed1985

Alternative statistical models for the examination of clinical positron emission tomography/fluorodeoxyglucose data.

This article describes a method for partitioning metabolic variability found in positron emission tomography/[18F]fluorodeoxyglucose studies. For the 15 subjects examined, 74.8% of the total metabolic variability could be ascribed to individual differences in global metabolic rate, whereas 15.8% of the total variability was consistent regional variation or pattern across subjects. Subsequently, the method of Q-component analysis is described for the identification of strong- and weak-pattern subjects. In addition, a standardization procedure that amplifies the observed pattern by removing systematic individual differences is described. Finally, the implications of these findings and methods for future and clinical studies are discussed.

Adolescent↗
PubMed1985

Isoquinoline is a possible anti-psoriatic agent in coal tar.

Isoquinoline has been identified as a component of coal tar which causes interfollicular regions of parakeratotic stratum corneum in mouse tail epidermis to become orthokeratotic, with concomitant production of a granular layer. In this respect it behaves similarly to coal tar itself, and isoquinoline may contribute to the anti-psoriatic activity of coal tar.

Animals↗
PubMed1985

Changes in concentrations and rate of decline of adrenaline in the medial preoptic area and mediobasal hypothalamus of acutely ovariectomized steroid-treated rats.

The presence of adrenaline within the central nervous system appears to be essential for the occurrence of an oestrogen-stimulated surge of LH in both pro-oestrous and ovariectomized rats. Previous measurements of adrenergic activity based on the rate of decline of adrenaline (RDA) 2 h after injection of a synthesis inhibitor (SKF 64139) suggested that adrenergic activity increases in both the medial preoptic area (MPOA) and the mediobasal hypothalamus (MBH) at the start of the LH surge (15.00-17.00 h). The purpose of the present studies was to see whether oestrogen and progesterone affected this increase in adrenergic activity at the sites of the cell bodies (MPOA) and axon terminals (MBH) of the gonadotrophin-releasing hormone-synthesizing neurone. Rats ovariectomized at dioestrus showed a reduction in both plasma LH concentrations and RDA (P less than 0.01) in the MBH between 15.00 and 17.00 h on the day of expected pro-oestrus. Oestrogen replacement at operation restored LH levels and the RDA to values found in intact rats. Injection of an antioestrogen (Cl-628), with or without oestrogen, also reduced plasma LH levels and the RDA (P less than 0.01) in the MBH. Removal or replacement of oestrogen apparently had little effect on the RDA in the MPOA. In ovariectomized oestrogen-primed rats an injection of progesterone on the morning of expected pro-oestrus advanced and enhanced not only the LH surge but also the RDA in the MBH (P less than 0.001). Moreover, concentrations of adrenaline in the MBH (but not the MPOA) decreased (P less than 0.001) consistently over a 2-h period following injection of progesterone.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗