Search PubMed⌕ Search

Biomedical subjects

S Nichols

Publications and source records attributed to S Nichols.

At least 19 recordsLinked to original sources
PubMed2005

Weight, fat mass, and central distribution of fat increase when women use depot-medroxyprogesterone acetate for contraception.

OBJECTIVE: To compare longitudinal changes in weight, body fat, and ratio of central to peripheral fat mass among first-time depot-medroxyprogesterone acetate (DMPA) users to women using no hormonal contraception, and to evaluate user characteristics associated with that change. DESIGN: Prospective longitudinal study. SUBJECTS: Healthy women, aged 18-35 y, using DMPA for contraception (n=178) and women using no hormonal contraception (n=145). MEASUREMENTS: Weight, body fat, and the central distribution of fat, measured at 3-month intervals for 30 months, by electronic scale and dual-energy X-ray absorptiometry (DEXA). The ratio of central to peripheral distribution of body fat was computed by dividing the body fat in the conventional DEXA trunk region of interest (ROI) by the ROI's that encompass the arms, hips and legs. RESULTS: Women using DMPA had a significantly greater increase in all measures of fatness than women using no hormonal method of contraception (P<0.03). The observed weight of DMPA users increased from a mean of 69.4 kg (s.d.=16.9) at baseline to 75.5 kg (s.d.=25.0) at 30 months; an increase of 6.1 kg (8.8.%). Fat mass increased from a mean of 25.3 kg (s.d.=12.6 kg) at baseline to 31.4 kg (s.d.=17.8); an increase of 6.1 kg (23.6%) in DMPA users. The ratio of central to peripheral fat mass in DMPA users changed from 0.95 (s.d.=0.155) at baseline to 1.01(s.d.=0.198) at 30 months. In contrast, weight, fat mass and the ratio of central to peripheral fat mass of control participants remained virtually unchanged over the same time period. Women with higher baseline physical activity levels had a smaller increase in body fat (P=0.003) and the fat ratio (P=0.03), but not weight (P=0.48). No other user characteristics including, smoking, past oral contraceptive use or previous pregnancies predicted change in level of fatness. CONCLUSIONS: This study has demonstrated a change in body composition toward greater fatness and toward a central redistribution of fat among DMPA users as compared to controls and provides important information to be used when counseling women regarding contraceptive methods. Given the potential long-term implication of these changes, further study is recommended to determine whether the gains in fatness are reversed following DMPA discontinuation and to examine the role of progestins in the development and maintenance of obesity.

Absorptiometry, Photon↗
PubMed2005

The quality of health research reporting by the daily newspapers in Trinidad and Tobago.

In this study, the authors examined the scientific quality of health research reported in the three daily newspapers in Trinidad and Tobago. All medical research articles published for the period January 1 to December 31, 2003, were extracted using a standardized data collection form. The scientific quality of the articles was analyzed by taking into consideration various aspects of study design, as well as other issues associated with accurate reporting. Of the 321 eligible articles, 108 were collected from The Trinidad Express, 100 from The Trinidad Guardian and 113 from The Trinidad and Tobago Newsday. The percentages of articles reporting methodological components consistent with good scientific quality were as follows: objective(s) (99.7%), study design (79.8%), study procedure (70.1%), selection procedure (70.1%), description of participants (87.5%), control/matching group (74.9%), outcome variables (99.4%) and issues of validity and reliability (2.5%). In addition, the percentage of articles containing aspects of good report writing were as follows: authorship (71.3%), authors' affiliation (59.5%), location of the study (25.4%), source of the research material (83.1%), duration of the study (27.7%), study setting (72.0%), number of participants (74.1%), period in which the study was conducted (12.0%) and quantification of the results (66.7%). Observational studies were significantly more likely to be reported than experimental studies (71.5% versus 28.5%). Overall, articles reported in the Trinidad Express and the Trinidad and Tobago Newsday were of a better scientific quality than those in the Trinidad Guardian. These findings suggest a need to improve the overall scientific quality of reported health research in these newspapers by ensuring that reports answer the fundamental questions of what, why, who, where, when and how. This might be achieved by adopting a structured reporting format similar to that used by many peer-reviewed journals.

Confidence Intervals↗
PubMed2005

A content analysis of health research reported by the daily newspapers of Trinidad and Tobago.

The ability to translate health research into useful information for the layperson requires both excellent scientific expertise and communication skills that are often foreign to journalist and editors. In this study, we assessed the content of health research articles published in the local daily newspapers for the year 2003. Issues considered included physical presentation, coverage, primary content of the article relative to the country health profile, accuracy of the article compared to its original publication, health model (ie preventative versus medical/curative) and tone (emotive nature of the report, stakeholder addressed). The authors identified 321 eligible articles as follows, The Trinidad Express (108), The Trinidad Guardian (100) and The Trinidad and Tobago Newsday (113). More than 90% of the reports appeared in the newspapers within two weeks of their original journal publication; 10.5% of the articles had over 50% newspaper readership coverage. Headlines were prominently displayed for 70% of articles while 86% of the written text were located on the top right and left quadrant of pages where the eye naturally falls during reading. Photographs accompanied 36% of the articles. Approximately 72.5% of articles accurately reflected the content of the original publication and 67% of them were classified as preventative. There were similar proportions of good (45%) and bad (47%) articles. The top five predominant themes were nutrition (24.3%), cancer (18.2%) women's health (17.6%), heart disease (14.2%) and mental health (10.3%). The findings suggest a tremendous effort by journalist and editors to provide relevant health information in a timely and attractive manner; however, this should not be at the expense of accuracy.

Developing Countries↗
PubMed2002

Socio-demographic and health system factors in relation to exclusive breast-feeding in Tobago.

To determine the prevalence and significant correlates of exclusive breast-feeding among nursing mothers, we conducted a survey among nursing mothers attending the Wellness Baby Clinic in Tobago from July 1 to December 1, 1998. A random sample of 151 mothers had face-to-face interviews with a standardized pretested questionnaire. Our results suggest that 48.3% and 20.8% of infants were exclusively breast-fed at two and four months respectively. Univariate logistic regression analyses showed that exclusive breast-feeding at two months was significantly positively associated with years of schooling completed by the mother, frequency of prenatal visits, mode of breast-feeding, mother's knowledge of the recommended duration of breast-feeding, and occupation of the child's father. Exclusive breast-feeding at four months was significantly positively associated with mother's age, years of schooling completed by the mother, frequency of prenatal visits, mother's knowledge of the recommended duration of breast-feeding, years of schooling completed by the child's father and occupation of the child's father. In multivariate logistic analyses, adjusting simultaneously for all relevant explanatory variables, exclusive breast-feeding at two months was significantly positively associated with frequency of prenatal clinic visits, mode of breast-feeding, mother's knowledge of the recommended duration of breast-feeding and occupation of the child's father. In addition, exclusive breast-feeding at four months was significantly positively associated with frequency of prenatal clinic visits, length of hospital stay, mother's knowledge of recommended duration of breast-feeding, years of schooling completed by the child's father, family structure and inversely associated with mother's age. In this sample, parental socio-demographic characteristics and health system factors were associated with subsequent infant feeding practices.

Adult↗
PubMed2001

Diagnosis of primary HIV-1 infection. Los Angeles County Primary HIV Infection Recruitment Network.

BACKGROUND: The optimal approach for diagnosing primary HIV-1 infection has not been defined. OBJECTIVE: To determine the usefulness of symptoms and virologic tests for diagnosing primary HIV-1 infection. DESIGN: Prospective cohort study. SETTING: A teaching hospital in Los Angeles and a university research center in San Diego, California. PATIENTS: 436 patients who had symptoms consistent with primary HIV infection. MEASUREMENTS: Clinical information and levels of HIV antibody, HIV RNA, and p24 antigen. RESULTS: Primary infection was diagnosed in 54 patients (12.4%). The sensitivity and specificity of the p24 antigen assay were 88.7% (95% CI, 77.0% to 95.7%) and 100% (CI, 99.3% to 100%), respectively. For the HIV RNA assay, sensitivity was 100% and specificity was 97.4% (CI, 94.9% to 98.9%). Fever, myalgia, rash, night sweats, and arthralgia occurred more frequently in patients with primary infection (P < 0.05). CONCLUSIONS: No sign or symptom allows targeted screening for primary infection. Although assays for HIV RNA are more sensitive than those for p24 antigen in diagnosing primary infection, they are more expensive and are more likely to yield false-positive results.

Antibodies, Viral↗
PubMed2000

Goal attribution in chimpanzees.

Does the chimpanzee attribute goals to others? Recent infant studies using the looking time measure have been interpreted as evidence that human infants attribute goals. An experiment modeled on these studies was carried out on chimpanzees, and the chimpanzees responded the way infants do. This indicates that chimpanzees also attribute goals and hence that this capacity is not distinctively human.

Animals↗
PubMed2000

A cognitive theory of pretense.

Recent accounts of pretense have been underdescribed in a number of ways. In this paper, we present a much more explicit cognitive account of pretense. We begin by describing a number of real examples of pretense in children and adults. These examples bring out several features of pretense that any adequate theory of pretense must accommodate, and we use these features to develop our theory of pretense. On our theory, pretense representations are contained in a separate mental workspace, a Possible World Box which is part of the basic architecture of the human mind. The representations in the Possible World Box can have the same content as beliefs. Indeed, we suggest that pretense representations are in the same representational "code" as beliefs and that the representations in the Possible World Box are processed by the same inference and UpDating mechanisms that operate over real beliefs. Our model also posits a Script Elaborator which is implicated in the embellishment that occurs in pretense. Finally, we claim that the behavior that is seen in pretend play is motivated not from a "pretend desire", but from a real desire to act in a way that fits the description being constructed in the Possible World Box. We maintain that this account can accommodate the central features of pretense exhibited in the examples of pretense, and we argue that the alternative accounts either can't accommodate or fail to address entirely some of the central features of pretense.

Adult↗
PubMed2000

A proposed aquatic plant community biotic index for wisconsin lakes.

The Aquatic Macrophyte Community Index (AMCI) is a multipurpose tool developed to assess the biological quality of aquatic plant communities in lakes. It can be used to specifically analyze aquatic plant communities or as part of a multimetric system to assess overall lake quality for regulatory, planning, management, educational, or research purposes. The components of the index are maximum depth of plant growth; percentage of the littoral zone vegetated; Simpson's diversity index; the relative frequencies of submersed, sensitive, and exotic species; and taxa number. Each parameter was scaled based on data distributions from a statewide database, and scaled values were totaled for the AMCI value. AMCI values were grouped and tested by ecoregion and lake type (natural lakes and impoundments) to define quality on a regional basis. This analysis suggested that aquatic plant communities are divided into four groups: (1) Northern Lakes and Forests lakes and impoundments, (2) North-Central Hardwood Forests lakes and impoundments, (3) Southeastern Wisconsin Till Plains lakes, and (4) Southeastern Wisconsin Till Plains impoundments, Driftless Area Lakes, and Mississippi River Backwater lakes. AMCI values decline from group 1 to group 4 and reflect general water quality and human use trends in Wisconsin. The upper quartile of AMCI values in any region are the highest quality or benchmark plant communities. The interquartile range consists of normally impacted communities for the region and the lower quartile contains severely impacted or degraded plant communities. When AMCI values were applied to case studies, the values reflected known impacts to the lakes. However, quality criteria cannot be used uncritically, especially in lakes that initially have low nutrient levels.

Journal Article↗
PubMed2000

Attention in HIV-infected children: results from the Hemophilia Growth and Development Study.

Attentional functioning was examined in three groups of 7- to 19-year-old male participants with hemophilia: (1) HIV seronegative controls (HIV-, N = 66), (2) HIV seropositive participants with CD4+ lymphocyte counts greater than or equal to 200 (HIV+ CD4+ > or = 200, N = 79), and (3) severely immune suppressed HIV seropositive participants (HIV+ CD4+ < 200, N = 28). Two measures sensitive to attention deficits were used: the Continuous Performance Test (CPT) and the Span of Apprehension (Span). On the CPT, there was a decrement in attention in both HIV+ groups, as indexed by an increase in false alarm rate from Block 1 to Block 3, that was not present in the HIV- group. The longer the HIV+ children were required to sustain attention to the CPT, the more they responded to the incorrect stimulus. This effect decreased as age increased. Span percent correct and latency to correct were associated with the presence of a premorbid history of intracerebral hemorrhage, but were not sensitive to HIV status or degree of immune suppression in the HIV+ children, suggesting morbidity related to hemophilia. The remaining CPT and Span variables--hit rate, sensitivity, latency, percent correct, and latency to correct--showed the expected associations with age, but none showed conclusive associations with HIV status or immune suppression in the HIV+ participants.

Adolescent↗
PubMed2000

HIV-associated changes in adaptive, emotional, and behavioral functioning in children and adolescents with hemophilia: results from the Hemophilia Growth and Development Study.

OBJECTIVE: To assess changes in adaptive, emotional, and behavioral functioning over four years in children and adolescents with hemophilia and with or without HIV infection and to evaluate the relationship of these changes to immune status. METHODS: Participants were 277 HIV-seropositive and 126 HIV-seronegative boys with hemophilia. Participants with HIV infection were divided into three groups based on trajectory of immune functioning (CD4+ cell counts) over the course of the study. Caregivers completed the Vineland Adaptive Behavior Scales and Pediatric Behavior Scale (PBS). RESULTS: Results showed declining Vineland Communication scores for participants with consistently poor immune functioning. These participants also started with more PBS Attention Deficit and Deviation symptoms, which then decreased more sharply than for other groups. Low CD4+ counts were consistently associated with more Health and Depression-Anxiety symptoms on the PBS. However, with few exceptions, group means remained within normal limits. CONCLUSIONS: According to their caregivers, boys with hemophilia and HIV infection showed considerable resilience with regard to adaptive behavior and emotional and behavioral problems. However, over time changes occurred in these areas that appear to be related to immune functioning.

Adaptation, Psychological↗
PubMed1999

Correlations of glutathione peroxidase activity with memory impairment in adults with Down syndrome.

BACKGROUND: Down syndrome (DS) is a genetic disorder (trisomy 21 in 96% of cases), associated with an excess of a key enzyme involved with free radical metabolism (FRM), superoxide dismutase-1 (SOD-1), that is encoded by a gene on chromosome 21. Consequently, SOD-1 activity is elevated in DS, which also occurs in conditions of oxidative stress, and is associated with a compensatory increase in glutathione peroxidase activity (GSHPx). METHODS: This study examined the relationship of memory function with erythrocyte SOD-1, GSHPx and catalase (CAT) activity in 22-51 year old adults with DS. RESULTS: Mean erythrocyte SOD-1 (p < .02) and GSHPx (p < .01), but not CAT (p = .76), activities were significantly greater in the DS group than the controls. In the DS group, erythrocyte GSHPx, but not SOD-1 or CAT activities, was significantly correlated with memory function (r = .625, p < .025, df = 13 for savings score, r = .631, p < .01, df = 14 for intrusion errors) but not with intelligence quotients. CONCLUSIONS: These observations suggest a possible relationship between altered FRM with memory deficits among adults with DS within the age-range in that an age-related increase in the prevalence for Alzheimer's neuropathology is known to be robust before reaching a plateau of 100%.

Adult↗
PubMed1999

Physical ergonomics of virtual environment use.

This paper describes an investigation of the types of problems that may be experienced by Virtual Reality (VR) users. Initial concerns have been voiced about various issues concerning the design of VR equipment, particularly the physical ergonomics of head-mounted displays (HMDs) and hand-held input devices, and the problems associated with display resolution and lags. This study investigated a number of VR users' perceptions of the types of physical ergonomics issues that they were aware of when participating in a number of different virtual environments (VEs), using different VR systems. Several different methods were employed, including questionnaires, body mapping, user observation and interviews. Issues highlighted as either causing participants discomfort or interfering with their experience of the VE were: discomfort from static posture requirements, general discomfort from wearing the HMD, difficulty becoming accustomed to 3D hand held input devices, dissatisfaction with deficits in the visual display and fear of getting 'tangled' in connecting cables. The implications of these findings for developers, implementers and users of VR are discussed.

Adult↗
PubMed1999

Age-related changes in children's use of external representations.

This study explored children's use of external representations. Experiment 1 focused on representations of self: Self-recognition was assessed by a mark test as a function of age (3 vs. 4 years), delay (5 s vs. 3 min), and media (photographs vs. drawings). Four-year-olds outperformed 3-year-olds; children performed better with photographs than drawings; and there was no effect of delay. In Experiment 2, 3- and 4-year-olds used a delayed video image to locate a sticker on themselves (self task) or a stuffed animal (other task). The 2 tasks were positively correlated with age and vocabulary partialed out. Experiment 3 used a search task to assess whether children have particular difficulty using external representations that conflict with their expectations: 3- and 4-year-olds were informed of an object's location verbally or through video: on half of the trials, this information conflicted with children's initial belief. Three-year-olds performed worse than 4-year-olds on conflict trials, indicating that assessments of self and other understanding may reflect children's ability to reason about conflicting external representations.

Child Development↗
PubMed1998

A randomized comparative trial of stavudine (d4T) versus zidovudine (ZDV, AZT) in children with human immunodeficiency virus infection. AIDS Clinical Trials Group 240 Team.

OBJECTIVES: To compare the safety and tolerance of stavudine (d4T) versus zidovudine (ZDV, AZT) in symptomatic human immunodeficiency virus-infected children 3 months to 6 years of age. METHODS: In an initially double-blind trial, 212 evaluable human immunodeficiency virus-infected children who had received no more than 6 weeks of previous antiretroviral therapy were randomized to receive either d4T (1 mg/kg orally every 12 hours, maximum 40 mg orally every 12 hours) or zidovudine (180 mg/m2 orally every 6 hours, maximum 200 mg orally every 6 hours). The study was unblinded after a median follow-up period of 6.3 months; median follow-up at study closure was 17.3 months. Tolerance, safety, disease progression, and immunologic responses were evaluated. RESULTS: The patient population was young (median age, 1.2 years; range, 0.3 to 6.4 years), with a median baseline CD4+ lymphocyte count of 965 cells/microL (range, 18 to 4238 cells/microL). Neutropenia < 400/microL occurred significantly more commonly among zidovudine recipients (1-year event rates of 20% both up to the time of unblinding and throughout the entire study) than among children receiving d4T (1-year event rates of 5% up to the time of unblinding and 6% throughout the entire study). In exploratory activity analyses using all data collected until study closure, children treated with d4T showed consistently greater positive changes from baseline in weight-for-age-and-gender z scores. As expected in this population of young children, median absolute CD4+ lymphocyte counts decreased in both treatment groups. Smaller changes from baseline were noted among d4T recipients. CONCLUSIONS: In children between the ages of 3 months and 6 years, d4T and zidovudine are largely comparable in terms of safety and tolerance. Neutropenia occurs significantly less commonly among children treated with d4T. There was evidence that weight gain and absolute CD4+ lymphocyte counts were better maintained in children receiving d4T.

Anti-HIV Agents↗