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Biomedical subjects

D R Harris

Publications and source records attributed to D R Harris.

At least 37 records · Page 2Linked to original sources
PubMed1993

A work-site nutrition intervention: its effects on the consumption of cancer-related nutrients.

OBJECTIVES: In a work-site nutrition intervention targeting fat and fiber, we examined the intervention's effect on specific nutrients implicated in carcinogenesis, including trace metals, vitamins, and categories of fatty acids. The rationale was based on the association observed in a variety of epidemiologic studies between these nutrients and epithelial cancers. METHODS: Data were taken from eight control companies and five intervention companies that fully implemented the Treatwell intervention. Analyses of variance were used preserving the study's nested design. RESULTS: Significant intervention-related associations were observed for increased total vitamin A and carotene. Marginal intervention effects were observed for relative decreases in the percentage of calories from both saturated and monounsaturated fatty acids, a relatively smaller increase in the percentage of calories from polyunsaturated fatty acids, and an increase in the consumption of vitamin B6. CONCLUSIONS: Results indicate a broader effect of the intervention than on fat and fiber only. Increased intake of carotene, the single most important of these other nutrients, is plausibly related to a variety of epithelial cancers.

Diet↗
PubMed1993

Effect of a community health center intervention on breast cancer screening among Hispanic American women.

OBJECTIVE: A multiple component intervention in a community health center is presented, and its effect on breast cancer screening participation by Hispanic American women between the ages of 45 and 75 years is discussed. DATA SOURCES/STUDY SETTING: In 1990, data were collected through a retrospective audit (at least as far back as 1987) of community health center medical records, as well as from a client referral log. The health center, located in a small Massachusetts city, primarily serves clients of Latino heritage. STUDY DESIGN: The study used a nonexperimental pretest-posttest intervention design to document clients' screening activities. To control for uneven length of enrollment, aging of the population, and sporadic utilization, the unit of analysis chosen for the principle study variables was an "eligible year." DATA COLLECTION: Variables of interest included screening (clinical breast exam and mammography), periodicity of screening, and compliance with referrals. PRINCIPAL FINDINGS: Postintervention, considerably greater screening mammography occurred among all age groups, more women had at least one screening mammogram during the period, more clinical breast exams included a mammogram referral, and the compliance rate improved. The rate of clinical breast exam did not significantly improve, showing a downward trend.

Age Factors↗
PubMed1992

Changes in mammography use: economic, need, and service factors.

OBJECTIVES: The purpose of this study was to document changes in mammography use between 1987 and 1990 and assess the relationship of use to selected economic, need, and health system factors. METHODS: Independent random-digit-dialed telephone surveys of women between 52 and 75 years of age were conducted. RESULTS: Between 1987 and 1990, the proportion of women who had had a mammogram in the past year increased from 31% to 51%. Though income was significantly related to overall patterns of use, it was not associated with recent mammogram use in 1990. Women with a family history of breast cancer reported greater use at both times, as did women who reported having a regular physician (particularly a gynecologist or internist). When all other variables were controlled for, women were over nine times more likely to have had multiple and recent mammograms in 1990 than in 1987. CONCLUSIONS: Mammography use dramatically increased between 1987 and 1990. There were strong relationships between the type of regular physician and mammography screening and between economic and personal history and repeated and recent mammography use.

Aged↗
PubMed1992

Work-site nutrition intervention and employees' dietary habits: the Treatwell program.

In a randomized, controlled study of the Treatwell work-site nutrition intervention program, which focused on promoting eating patterns low in fat and high in fiber, 16 work sites from Massachusetts and Rhode Island were recruited to participate and randomly assigned to either an intervention or a control condition. The intervention included direct education and environmental programming tailored to each work site; control work sites received no intervention. A cohort of workers randomly sampled from each site was surveyed both prior to and following the intervention. Dietary patterns were assessed using a semiquantitative food frequency questionnaire. Adjusting for work site, the decrease in mean dietary fat intake was 1.1% of total calories more in intervention sites than in control sites (P less than .005). Mean changes in dietary fiber intake between intervention and control sites did not differ. This study provides evidence that a work-site nutrition intervention program can effectively influence the dietary habits of workers.

Adolescent↗
PubMed1991

Acute thyroid hormone promotes slow inactivation of sodium current in neonatal cardiac myocytes.

Sodium current (INa) inactivation kinetics in neonatal cardiac myocytes were analyzed using whole cell voltage clamp before and after acute treatments with thyroid hormone (3,5,3'-triiodo-L-thyronine, T3). In untreated neonatal myocytes, INa inactivation was predominantly mono-exponential, with 93 +/- 3% (S.D.; n = 9) of the peak amplitude decaying with a time constant, tau h1, of 1.8 +/- 0.5 ms at -30 mV. The remaining 7% of control INa decayed more slowly, with a time constant, tau h2, of 9.3 +/- 3.0 ms at -30 mV. The contribution of slowly-inactivating channels to peak current was increased from 7% to 43 +/- 27% within 5 min of exposure to 5-20 nM T3 (nine cells; P less than 0.005). The time constants for both the fast- and slow-inactivating components of peak current (tau h1 and tau h2) were not significantly changed by acute T3 treatment, nor was steady-state INa inactivation (h infinity) affected. Thyroid hormone action on sodium inactivation was partially reversible by lidocaine. These findings indicate that T3 acts at the neonatal cardiac cell membrane to promote slow inactivation kinetics in sodium channels.

Animals↗
PubMed1991

Evaluation of a standardized survey design proposed for use in epidemiological research on AIDS.

A Monte Carlo model simulating actual populations was employed to evaluate the precision in estimation of a standardized sampling method proposed by the Global Programme on AIDS of the World Health Organization, for general use in collecting population-based data on HIV seroprevalence. It appears that in real populations, where there is likely to be 'pocketing' of infection, the proposed methodology will generally fail to provide estimates accurate to within 1% of the true population value. However, if the primary objective of a particular survey is to construct confidence intervals that include the true population HIV seroprevalence rate, then this survey method appears to be a reasonable choice. This study also suggests that selection of only one adult per household improves the precision of resulting estimates. However, since selection of only one adult per household would require that more households be visited, any gain in precision would need to be weighed against the likely increase in cost of household visits.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Validity and reliability of psychosocial factors related to breast cancer screening.

This research explored the construct validity of hypothesized survey items and data reduction procedures for selected psychosocial constructs which are frequently used in breast cancer screening research. Factor analysis was used to validate relationships between survey items and hypothesized constructs suggested by several theories of behavior change. These constructs included perceived barriers and benefits of breast cancer screening compliance behavior. Reliability analyses were then used to evaluate the consistency of the resultant scales applied across three data sets, resulting from surveys conducted by two different methods (telephone and in-person interview) over three time periods. These analyses found reliability coefficients ranging from .53 to .69.

Adult↗
PubMed1991

Evaluation of the EPI survey methodology for estimating relative risk.

Precision in estimation of relative risks using a standardized sampling method proposed by the WHO Global Programme on AIDS was evaluated using a Monte Carlo model simulating actual populations; the proposed survey design represents a modification of the methodology used by the WHO Expanded Programme on Immunization (EPI) to estimate immunization coverage among children. This study suggests that in actual populations the proposed survey strategy is a reasonable alternative to the use of simple random sampling (SRS) at the second stage of cluster sampling. Although varying such population characteristics as the seroprevalence rate, nonresponse rate, and rate of misclassification of exposure failed to demonstrate a clear advantage of one method over the other, the added cost and difficulty of implementing SRS under field conditions warrant further consideration of the EPI-like methodology for use in estimating relative risks.

Adult↗
PubMed1990

Acute effects of thyroid hormone on sodium currents in neonatal myocytes.

Sodium currents and action potentials were recorded from myocytes of neonatal rats during acute exposure to thyroid hormone (5-20 nM). One to 5 minutes after addition of thyroid hormone to the bath, decay from peak Na current was slowed, with the fractional current flowing 20 ms after onset (relative to peak current) increasing from 6 +/- 5% to 17 +/- 13% (p less than 0.01, n = 12). Action potential durations were increased from 55 +/- 14 to 86 +/- 36 msec (p less than 0.05, n = 6). The effects of thyroid hormone were partially reversed by lidocaine (60 microM, n = 5), a specific blocker of a slow sub-population of Na channels. Thus thyroid hormone interacts directly with myocyte membrane, probably by slowing of inactivation of Na channels.

Action Potentials↗
PubMed1988

Rat enterohepatic circulation and intestinal distribution of enterally infused thyroid hormones.

The enterohepatic circulation (recycling), intestinal (gut) distribution, metabolism, and excretion of enterally infused thyroid hormones were studied in the intact rat under approximately normal physiological steady state conditions. Rats with 7-day osmotic minipumps implanted ip received constant intraduodenal infusions to steady state of very small trace doses of either 125I-labeled T3 (T3*) or T4 (T4*). Enterohepatic and other pathways remained open to normal function, and in particular, there was no biliary diversion or ligation. Complete feces and urine were collected daily, to assess daily distributions of radioactivity and establishment of the steady state, which occurred by day 3. On day 7, rats were anesthetized, blood was sampled, whole intestine and minipumps were removed, and the gut was separated into six segments. Fecal samples and the contents of each gut section were homogenized, ethanol extracted, evaporated, and reconstituted in NaOH for quantitative aqueous chromatography along with infusate, urine, and plasma samples, on Sephadex G-25 columns. No T3* or T4* was found in urine, but feces contained 39% of the T3* infused and 36% of the T4* infused in steady state. Statistically significant amounts of both T3* and T4* in systemic plasma on day 7 clearly indicated absorption of the hormones from the intestine, distinctly demonstrating an enterohepatic circulation of T3 and T4 under experimental conditions closely approximating the physiological steady state. This also establishes the intestine (with its contents) as an exchangeable hormone pool, physiologically internal to the system regulating thyroid hormones and their distribution. Gut contents contained 52 times more T3* and 4.34 times more T4* than corresponding plasma pools in steady state. Kinetic analysis of the data indicated that somewhat more than half of the T3* or T4* infused was absorbed from gut to liver (primary absorption), and up to 34% of the T3* infused and 43% of the T4* infused reached the systemic circulation (secondary absorption/bioavailability). Gut contents longitudinal distribution data 1) confirm existing evidence that thyroid hormone conjugates, formed elsewhere, exist in gut contents and are hydrolyzed there; 2) demonstrate that deconjugation becomes quantitatively significant, and thus may be initiated, at the level of the cecum; and 3) strongly suggest that absorption of unconjugated hormone occurs from at least the small intestine, all under normal physiological conditions.

Animals↗
PubMed1988

Association of electronic fetal monitoring during labor with cesarean section rate and with neonatal morbidity and mortality.

Data from the 1980 National Natality Survey by the National Center for Health Statistics were used to assess the relation of electronic fetal monitoring (EFM) during labor with cesarean section rates and neonatal morbidity and mortality. In univariate analyses, EFM was associated with higher cesarean section rates, lower five-minute Apgar scores, and a higher rate of respiratory distress. Logistic regression analysis controlling for other risk factors for poor neonatal outcome indicated that the association of EFM with higher cesarean section rates persisted (odds ratio 1.45, 95% CI 1.16, 1.81), except in certain pregnancies at very high risk for cesarean section. EFM was associated with an Apgar score less than 6 at five minutes only if delivery was by cesarean section. EFM was not found to be independently associated with respiratory distress. Neither univariate nor multivariate analyses found an association of EFM with neonatal mortality. These results suggest that EFM may identify hypoxic infants, who are frequently delivered by cesarean section. The lack of association of EFM with beneficial neonatal outcomes is consistent either with lack of effect of EFM or with uncontrolled selection bias.

Apgar Score↗
PubMed1988

Spontaneous abortion and general illness symptoms among semiconductor manufacturers.

The risk of adverse reproductive outcomes was examined among semiconductor manufacturers. Personal interviews were conducted with manufacturing workers, spouses of male manufacturers, and an internal comparison group of non-manufacturing workers. Elevated spontaneous abortion ratios were observed for females working in the "diffusion" (38.9%; relative risk = 2.18, 95% confidence interval estimate = 1.1, 3.6) and photolithographic process (31.1%; relative risk = 1.75, 95% confidence interval estimate = 0.8, 3.3). Analysis of potential confounding did not substantially alter the findings. The potential for recall bias was also assessed; although the confidence interval for the comparison of diffusion and non-manufacturing workers no longer excluded 1.0, an excess risk was still reflected. No substantive differences in other reproductive outcomes were identified. Various general health symptoms were examined and reported more frequently among manufacturers than non-exposed. These results should be viewed as tentative until studies with larger numbers and more detailed exposure data are carried out.

Abortion, Spontaneous↗
PubMed1986

Prostate cancer.

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Aged↗