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Biomedical subjects

C L Williams

Publications and source records attributed to C L Williams.

At least 217 records · Page 12Linked to original sources
PubMed1983

Effects of alterations in the heartbeat rate and locomotor activity of Schistosoma mansoni-infected Biomphalaria glabrata on cercarial emergence.

During a 27-hr period of food deprivation, Biomphalaria glabrata infected with Schistosoma mansoni had lower heartbeat rates and locomotor activities than did controls that were feeding ad lib. However, there was no difference between the cercarial emergence from control and experimental snails either before, during, or after the period of food deprivation. No correlation was found between the locomotor activity of the snail and the number of cercariae emerging from the snail in continuous light. Our results indicated that the emergence of S. mansoni cercariae from B. glabrata was not affected by the heartbeat rate or locomotor activity of the snail. The factors controlling the rhythm of S. mansoni cercarial emergence from B. glabrata may be independent of the snail.

Animals↗
PubMed1982

Activation and odor conditioning of suckling behavior in 3-day-old albino rats.

The circumstances under which a novel odor could elicit nipple attachment behavior in 3-day-old albino rats were investigated. In Experiment 1, rats suckled washed nipples scented with citral (a lemon odor) only if they either had received tactile stimulation (by stroking with a soft artist's brush) or had been administered amphetamine in the presence of citral prior to the suckling test. Pups stimulated in citral's absence or simply exposed to citral without stimulation failed to suckle such nipples. In Experiment 2, rats stimulated in a benzaldehyde (an almond odor) ambience suckled washed nipples scented with benzaldehyde but not those with citral scent. The opposite held for rats stimulated in a citral-rich environment. The stimulus conditions that support this conditioning were investigated in Experiment 3. Simultaneously increasing citral concentration and raising ambient temperature markedly attenuated the phenomenon. Experiment 4 demonstrated that not all classes of stimulation produced conditioning. Caffeine, in a wide range of doses, did not allow citral to elicit suckling on washed nipples. These findings are discussed within a framework of higher order conditioning. They may provide a mechanism by which naturally occurring stimuli come to elicit the species- and age-typical behavior of suckling.

Animals↗
PubMed1981

Safety and immunogenicity of a new Haemophilus influenzae type b vaccine in infants under one year of age.

64 healthy infants 2-3 months old, were randomly assigned to one of three vaccination groups which received either diphtheria-pertussis-tetanus (DPT) vaccine, Haemophilus influenzae type b capsular polysaccharide polyribosyl-ribitol phosphate (PRP) vaccine, or PRP + P (with pertussis adjuvant) vaccine in three doses at intervals of 2 months. Local and systemic reactions occurred most frequently after DPT vaccination and least frequently for PRP alone. Data for 60 infants from whom complete sera sets were available indicated that 70% of the infants who received three doses of PRP + P showed 2-fold or greater increases in titres of antibody to PRP with final values above the level assumed to give protection against invasive H. influenzae type b disease (greater than or equal to 0.15 microgram/ml). In contrast, less than 10% of the infants who received PRP vaccine alone showed 2-fold or greater increases.

Age Factors↗
PubMed1980

Impulsive suicidal behavior.

Previous studies have noted that a considerable proportion of suicidal behavior is impulsive. The present study aimed to ascertain the degree to which this was so and to consider whether impulsive attempters differed from non-impulsive attempters on variables such as demographic and motivational factors and circumstances that surrounded the occurrence of the act. Based on a criterion of less than 5 minutes' premeditation, 40% of two large, consecutive series were judged to have acted impulsively. While few variables differentiated between the two groups, impulsive attempters were less depressed, motivated by the desire to reduce tension, more likely to consider that they would survive, and to report that someone saw them perform the act.

Adult↗
PubMed1979

Selected chronic disease 'risk factors' in two elementary school populations. A pilot study.

Ninety-five first-grade elementary school students (aged 5 to 6 years) in two New York City area schools participated in a pilot test of a chronic disease primary prevention program stressing nutrition, antismoking, and physical activity. Program components included a health knowledge questionnaire; measurement of height, weight, skin-fold thickness, total serum cholesterol level, and blood pressure; and a modified Harvard step test of pulse rate recovery after exercise and subsequent classroom health education. The proportion of students with test values higher than specified critical levels was much greater in school M compared with school S. These measures will be repeated after one year to determine the feasibility and potential effectiveness of certain classroom health education activities.

Blood Pressure↗
PubMed1979

Reducing adolescent obesity through a school health program.

The feasibility and effectiveness of conducting a school-based multi-component behavioral weight reduction program was tested on 119 overweight junior high school students. Four schools in the metropolitan New York area were randomly assigned to either the experimental or control conditions. After participating in a school-wide health-profile screening, students in the experimental group were invited to participate in a ten-session weight reduction program that included behavior modification, nutrition education, and exercise management. Comparison of the experimental and control groups with respect to changes on weight and triceps skinfold measures indicated significant differences between the two groups. Although the long-term effectiveness of the weight reduction program cannot be determined, the present study clearly demonstrates the short-term effectiveness and feasibility of conducting such a program in a school setting.

Adolescent↗
PubMed1979

Inhibition of suckling in weaning-age rats: a possible serotonergic mechanism.

The nature, development, and specificity of serotonergic involvement in the control of suckling behavior in rat pups from 10 to 35 days of age were studied. During development, suckling normally declines after 10 days and is abandoned after 30 days. It was found that (a) methysergide, a serotonin (5-HT) receptor blocker, reinstated suckling behavior in pups 15 days of age and older but had no effect on the suckling of 10-day old pups, (b) quipazine, a 5-HT receptor agonist, inhibited suckling of pups 10 days of age and older, (c) methysergide pretreatment blocked the quipazine inhibition of suckling, and (d) metergoline, another 5-HT blocker, also stimulated suckling, and fenfluramine, a 5-HT releaser, blocked suckling in deprived pups. Together, these data support the hypothesis that a serotonergic inhibitory mechanism modulates the suckling of weaning-age rats. These pharmacological manipulations of 5-HT appear to alter specific components of suckling behavior involved in its initiation and maintenance but do not appear to alter a general hunger system.

Animal Population Groups↗
PubMed1979

Validation of students' self-reported cigarette smoking status with plasma cotinine levels.

Plasma cotinine levels were measured in 137 students (ages 14 to 17 years), as an independent validation of self-reported cigarette smoking status. Ninety-five per cent of the students who reported daily cigarette smoking had detectable cotinine levels. In contract, only 2 per cent of students who reported that they never smoke cigarettes had detectable levels of plasma cotinine. Results suggest that adolescents can report accurately on their smoking status if sufficient assurance of confidentiality is stressed.

Adolescent↗