Is the most frequent allele the oldest?
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Alleles↗
Biomedical subjects
H A Guess
Publications and source records attributed to H A Guess.
Confidence intervals and test of hypotheses concerning dose response relations inferred from animal carcinogenicity data.
Confidence intervals and hypothesis tests are developed for dose-response relations based on dichotomous data from animal carcinogenicity experiments. The functional form of the dose-response curve comes from the Armitage-Doll multistage carcinogenesis model and involves a polynomial in the dose-rate, with non-negative coefficients. Asymptotic distributions of the maximum likelihood estimators of these coefficients are used to construct confidence bounds on risk at a given dose and on the dose corresponding to a given risk. Likelihood ratio tests are developed for the presence of a positive dose-related effect and for the existence of a positive slope to the dose-response curve at zero dose. The latter test is of practical importance since a positive slope of the dose-response curve at zero dose rules out any "threshold-like" behavior and would often mean that any concentration low enough to insure a negligibly low cancer risk (e.g., 10(-6)) would be too low to be economically useful for applications such as food additives. Simulation experiments are performed to provide guidelines for applying the theory.
Animals↗
Evolution in finite populations with infinitely many types.
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Alleles↗
Theoretical and simulation results relating to the neutral allele theory.
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Alleles↗
The decision to seek care. Factors associated with the propensity to seek care in a community-based cohort of men.
OBJECTIVE: To investigate factors associated with a high propensity to seek care. DESIGN: Cross-sectional baseline component of a prospective cohort study. SETTING: Olmsted County, Minnesota. SUBJECTS: A randomly selected, community-based cohort of 2115 men aged 40 to 79 years on January 1, 1990. MEASUREMENTS: Participants completed a questionnaire that elicited information about the propensity to seek care by means of 7 hypothetical scenarios about physical illness. Also queried was the self-reported outpatient physician utilization in the previous year and sociodemographic factors. RESULTS: There was a significant association between propensity to seek care and physician utilization. Men with a high propensity to seek care were more likely to have had 4 or more physician visits (odds ratio [OR], 1.7; 95% confidence interval [CI], 1.3-2.3). Bivariate analysis suggested significant associations between a propensity to seek care for physical reasons and retirement (OR, 2.0; 95% CI, 1.1-2.6), age of 65 years or more (OR, 1.9; 95% CI, 1.5-2.4), incomplete high school education (OR, 1.6; 95% CI, 1.1-2.2), and an annual income of less than $25,000 (OR, 1.4; 95% CI, 1.1-1.9). Multivariable logistic regression analysis demonstrated that retired men were more likely to have a high propensity to seek care (OR, 1.7; 95% CI, 1.2-2.4), with the other variables no longer-being significant. CONCLUSIONS: Our findings suggest an association between propensity to seek care and physician utilization and retirement. In view of the increasing numbers of aged persons in the United States, this relatively higher propensity to seek health care among retired men may have a greater impact on the cost of health care for the aged than is fully appreciated.
Adult↗
People vaccinated by pharmacists: descriptive epidemiology.
OBJECTIVE: To describe the demographic, clinical, and attitudinal characteristics of people vaccinated by pharmacists, using a multistate sample of pharmacists and a more extensive set of parameters than previous studies. DESIGN: Cross-sectional survey. PATIENTS AND OTHER PARTICIPANTS: 1,730 adults vaccinated at 21 community pharmacies in 17 cities in 10 states. MAIN OUTCOME MEASURES: Vaccinees' age, sex, and selected demographic characteristics; current medications and prescription use patterns; distance traveled to pharmacy; and opinions about vaccine providers. RESULTS: 60% of respondents were women; average age was 54 +/- 15 years. One-quarter were age 65 years or older. About 9% were younger than 65 and took medication for chronic heart or lung disease or diabetes. Almost half took prescribed medications chronically, and 84% came to the pharmacy intending to be vaccinated. All of the respondents believed they were treated respectfully. Many respondents considered the pharmacy advantageous, compared with other vaccine providers, based on access, proximity, trust, convenience, and/or cost. CONCLUSION: Respondents vaccinated by a community pharmacist were satisfied with the experience and would recommend it to others.
Aged↗
Factors predictive of seizures among intensive care unit patients with gram-negative infections.
From the medical records of 238 intensive care unit (ICU) patients who had infections with gram-negative pathogens commonly associated with serious illness, we developed a predictive score of clinical risk factors for seizures. To evaluate the predictive ability of this score, we applied it to a separate population of 645 seriously ill hospitalized patients with similar gram-negative infections who were in antibiotic clinical trials. The patients at highest risk were classified into one of the following three categories: (a) patients with major central nervous system (CNS) insults (CNS surgery, hemorrhage, infection, or other lesion within 1 month before hospital admission or any history of CNS neoplasia), (b) patients with a predisposing factor (renal impairment or a history of seizures) plus a precipitating factor (anoxic encephalopathy/coma or an acute hypotensive episode), and (c) patients with both renal impairment and a history of seizures. Receiver operating characteristic (ROC) curves were calculated in each of the two populations. The area under the ROC curve (AUC) represents the probability that the score would rank a randomly chosen patient who subsequently had a seizure as having had a greater prior level of seizure risk than a randomly chosen patient who did not experience a seizure. The AUC was 0.87 (SE = 0.05) for the original population used to develop the score and 0.81 (SE = 0.04) for the population used for the validation study. The clinical risk score, based on readily available information, provides a useful means to identify among seriously ill infectious disease service patients, those who are at highest risk for seizures. It also serves as a baseline for evaluating the non-drug-related risk factors for seizures in patients treated with antibiotics.
Adult↗
The effect of dose on cancer latency period.
A number of animal carcinogenesis experiments have demonstrated that the time from initial exposure to first detection of tumors increases with decreasing dose. This observation has led to some speculation that at very low doses tumors would take so long to develop that life would end before tumors appeared. We show that the apparent increase in tumor development time can be easily seen as nothing more than a manifestation of the mathematical fact that decreasing the incidence necessarily increases the first time-to-tumor. No physical increase in tumor growth time need be postulated to explain the observations. Existing methods of low-dose risk extrapolation implicitly account for the increase in time-to-tumor statistics insofar as they account for the decrease in tumor incidence.
Animals↗
Vitamin D and prostate cancer: a prediagnostic study with stored sera.
This study evaluates the risk of prostate cancer in relation to serum levels of the major vitamin D metabolites, 25-hydroxyvitamin D (25-D3) and 1,25-dihydroxyvitamin D (1,25-D). Between 1964 and 1971, more than 250,000 serum samples were collected from members of the Kaiser Permanente Medical Care Plan in Oakland and San Francisco and stored for future use. Levels of 25-D and 1,25-D were measured in samples from 90 black and 91 white men diagnosed with prostate cancer before December 31, 1987 and controls individually matched on age, race, and day of serum storage. Mean serum 1,25-D was 1.81 pg/ml lower in cases than in matched controls (P = 0.002). Risk of prostate cancer decreased with higher levels of 1,25-D especially in men with low levels of 25-D. However, mean 25-D was not significantly different in cases and controls. The association of lower 1,25-D with prostate cancer was found in men above the median age of 57 years at serum storage but not younger men and was similar in black and white men. In men > or = 57 years of age, 1,25-D was an important predictor of risk for palpable and anaplastic tumors but not for tumors incidentally discovered during surgery to treat the symptoms of benign prostatic hyperplasia or well differentiated tumors.
Adult↗