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Biomedical subjects

S Hoag

Publications and source records attributed to S Hoag.

17 recordsLinked to original sources
PubMed2006

Comparison of bovine in vivo bioavailability of two sulfamethazine oral boluses exhibiting different in vitro dissolution profiles.

The bolus (or oblet) is a dosage form that can be used for the oral administration of pharmaceutical compounds to ruminating species. Unlike traditional tablets, oral boluses may contain quantities of drug on the order of grams rather than milligrams. Due to its size, it is only recently that USP-like in vitro dissolution methods have been developed for this dosage form. However, whether or not these dissolution tests can predict product in vivo performance has yet to be determined. The importance of this issue is apparent when the U.S. Food and Drug Administration Center for Veterinary Medicine is faced with the decision of whether to require additional in vivo bioequivalence study data to support the approval of changes in product chemistry or manufacturing method. The current study was undertaken to determine whether an in vivo/in vitro correlation can be established for bovine sulfamethazine oral boluses and to acquire insight into the magnitude of changes in in vitro product performance that can occur before corresponding changes are seen in in vivo blood level profiles. Based upon the results of this investigation, it is concluded that marked changes in in vitro sulfamethazine bolus performance can be tolerated before resulting in altered in vivo blood level profiles. However, the data also suggest that rumenal absorption may occur for some compounds. Therefore the degree to which variation in product in vitro dissolution profiles can be tolerated may be compound specific.

Administration, Oral↗
PubMed1998

Medicaid managed care and the marketplace.

In 1994 and 1995, Tennessee, Hawaii, Rhode Island, and Oklahoma began massive expansions of Medicaid managed care, growing from three health plans covering a few enrollees to 27 plans covering the great majority a year later. Some firms aggressively pursued expansion, while others had very limited business objectives. Although established insurers often dominated the Medicaid markets, newly developed firms, some provider-sponsored, were also important. Despite the relatively low Medicaid capitation rates in the 1996-97 period, Medicaid plans in three states had an average 1% net profit margin.

Capitation Fee↗
PubMed1996

Associations between dietary factors and serum lipids by apolipoprotein E polymorphism.

A geographically based observational study of 852 nondiabetic Hispanic and non-Hispanic white persons in southern Colorado aged 20-74 y was conducted to determine whether diet-lipid associations were modified by the apolipoprotein E (apoE, protein; APOE, gene) polymorphism. Subjects were seen for up to three visits from 1984 to 1992. A 24-h diet recall was collected and fasting serum lipid concentrations were measured at all visits. In longitudinal-regression analyses, dietary factors were significantly associated with serum lipid concentrations in the directions expected based on the large amount of literature on this topic. The positive relation between dietary cholesterol and serum total and low-density-lipoprotein cholesterol was strongest in Hispanic subjects with the APOE*2 allele (E2/ 2,3/2 genotypes) and non-Hispanic white subjects with the APOE*3 allele (E3/3 genotype), and there was no association in subjects with the APOE*4 allele (E4/3, 4/4 genotypes) in either ethnic group. No other statistically significant differences in the relations between dietary factors and serum lipid concentrations by APOE polymorphism were identified. These findings suggest that the APOE polymorphism plays only a minor role in modifying the association between dietary factors and serum lipids.

Adult↗
PubMed1996

Population screening for glucose intolerant subjects using decision tree analyses.

The purpose of this study was to develop a method of screening for impaired glucose tolerance and previously undiagnosed NIDDM that could be used preliminary to the administration of an oral glucose tolerance test (OGTT) for final classification of glucose tolerance status. The purpose of a preliminary screening of this type would be to reduce the number of OGTT's needed to identify cases of IGT and NIDDM in the population. We used NIDDM risk indicators and decision tree analysis methods (CART software) to identify subgroups of the population at increased risk. We examined a population of Hispanic (n = 583) and non-Hispanic white (n = 768) subjects without a prior history of diabetes. Subjects were classified as normal, IGT or NIDDM (WHO criteria) based on results from a 75 g oral glucose tolerance test (OGTT). Sensitivity (SEN) and specificity (SPE) of the CART models were calculated using the OGTT as the 'gold standard.' Two approaches to screening were simulated. In the simultaneous approach all risk variables were entered into CART models at once. In the serial approach, risk variables were grouped according to degree of effort required for data collection, and were entered into CART models in stages. Fasting glucose, age and body mass index (BMI) were selected as risk variables by CART when simulating the simultaneous approach (SEN = 91%, SPE = 55%). In the serial approach, CART used age and BMI to eliminate 35% of the population from further screening, and then used fasting glucose, glycohemoglobin, age and BMI to classify the remaining higher risk subjects (SEN = 85%, SPE = 64%). These models suggest that screening for IGT and previously undiagnosed NIDDM can be based on measurement of relatively simple indicators, and yet maintain a level of both sensitivity and specificity acceptable for this type of preliminary screening.

Adult↗
PubMed1995

Effect of diagnostic criteria on the prevalence of peripheral arterial disease. The San Luis Valley Diabetes Study.

BACKGROUND: The ankle/brachial systolic blood pressure index (ABI), a noninvasive measure of peripheral arterial disease (PAD), is widely used in epidemiological studies. However, the normal ranges of the ABI in healthy populations and ABI criteria for the diagnosis of PAD in large population studies have not been critically evaluated. METHODS AND RESULTS: The San Luis Valley Diabetes Study (SLVDS) was designed to evaluate the prevalence and complications of non-insulin-dependent diabetes mellitus (NIDDM) in a biethnic population. The present study was conducted as part of the SLVDS to assess the prevalence of vascular disease in 1280 nondiabetic control subjects and 430 patients with NIDDM. The ABI criteria for PAD were developed in 403 healthy individuals with a low risk for cardiovascular disease. In these low-risk subjects, the average resting ABI value was 0.07 lower in women than in men. In both sexes, the dorsalis pedis ABI was 0.04 lower than in the posterior tibial artery, and the left leg ABI was 0.02 lower than the right leg ABI (all differences, P < .05). In the low-risk subjects, ABI values were lower after exercise than at rest and had similar differences by sex and leg as observed at rest. Using specific abnormal cutoff points for the ABI, we evaluated three criteria for PAD in the overall population: two abnormal vessels in the same leg at rest (both dorsalis pedis and posterior tibial arteries), one abnormal vessel per leg at rest, and an ABI abnormality only after exercise. Subjects classified with PAD by the two-vessel criterion had a higher frequency of claudication and the physical finding of an absent pulse compared with subjects without PAD or patients with PAD defined by the one-vessel or exercise criterion. Use of the two-vessel criterion identified an increased risk of PAD with increasing age, NIDDM, smoking, hypertension, and elevated cholesterol levels. In contrast, the one-vessel PAD criterion was associated only with increasing age and smoking, and exercise-diagnosed PAD was not associated with any cardiovascular risk factor except for male sex. CONCLUSIONS: In low-risk subjects, the normal distribution and lower abnormal cutoff point values of the ABI differed by type of test, sex, ankle vessel, and leg. When these specific abnormal cutoff points were applied to the SLVDS population, the two-vessel abnormal criterion described patients with typical clinical characteristics of PAD and the expected associations of PAD with cardiovascular risk factors. These clinical characteristics and cardiovascular risk factor associations were less evident with PAD diagnosed by the one-vessel or exercise criterion. Therefore, an abnormal dorsalis pedis and posterior tibial ABI in the same leg at rest should be used for the diagnosis of PAD in epidemiological studies.

Adult↗
PubMed1995

High fasting insulin levels associated with lower rates of weight gain in persons with normal glucose tolerance: the San Luis Valley Diabetes Study.

OBJECTIVE: to investigate whether increased insulin resistance is associated with a reduced risk of weight gain among Hispanic and non-Hispanic white persons in Colorado. DESIGN: measurements were taken at baseline and after an average of 4.3 years. SUBJECTS: 789 normal glucose tolerant subjects 20 to 74 years of age were studied. MEASUREMENTS: fasting insulin levels were used as an indirect marker of insulin resistance. RESULTS: the average baseline body mass index (BMI) was 26.1 (+/- 3.6 s.d.) in men and 25.2 (+/- 4.4 s.d.) in women. The average weight change at follow-up was 0.8 kg (+/- 4.3 s.d.) in men and 1.3 kg (+/- 5.0) in women. A doubling in initial fasting insulin was associated with a reduced risk of gaining 5 kg (n = 134) and 10 kg (n = 24) of weight in logistic regression models (OR5kg = 0.76, 95% CI: 0.59, 0.99 and OR10kg = 0.61, 95% CI: 0.36, 1.02). Similarly, a doubling of initial fasting insulin was associated (P = 0.006) on average with a 6.3 kg less weight gain in linear regression models, independently of initial body weight, age, sex, ethnicity and BMI. The relation was consistently observed in men and women and in both ethnic groups. CONCLUSION: higher initial fasting insulin decreases the risk of subsequent weight gain in both Hispanic and non-Hispanic white normal glucose tolerant individuals similar to Pima Indians. This appears to be a common biologic characteristic in moderate to low as well as high risk populations for NIDDM.

Adult↗
PubMed1994

ApoA-IV polymorphism associated with myocardial infarction in obese NIDDM patients. The San Luis Valley Diabetes Study.

Non-insulin-dependent diabetes mellitus (NIDDM) confers myocardial infarction (MI) risk unexplained by known factors. In 356 NIDDM patients and 1,087 people with normal glucose tolerance, we investigated the association between MI risk and polymorphism at codon 360 in the apolipoprotein A-IV (apoA-IV) gene. During 1984-1992, MI was diagnosed in 84 diabetic and in 106 nondiabetic people. The risk of MI did not differ by apoA-IV phenotype in nondiabetic people; however, in NIDDM patients, those with the apoA-IV 1-2 phenotype had 2.8 (95% confidence interval: 1.4-5.6) higher MI risk than those with the 1-1 phenotype, adjusting for age, gender, ethnicity, hypertension, smoking, body mass index, fat centrality, and low-density lipoprotein and high-density lipoprotein cholesterol. The risk of MI was particularly high in obese NIDDM patients with the apoA-IV 1-2 phenotype: 5.1 (2.4-11.2) times that in obese apoA-IV 1-1 NIDDM patients and 7.7 (3.6-16.7) times that in lean nondiabetic people. The effect of apoA-IV 1-2 did not appear to be a part of the insulin-resistance syndrome nor was it dependent on diabetes duration or control. One half of the excess MI risk in the diabetic population studied was explained by the apoA-IV 1-2 phenotype. These results indicate that approximately 17% of NIDDM patients have a high MI risk apoA-IV phenotype that is particularly deleterious in obese patients.

Adult↗
PubMed1994

Dietary fat predicts conversion from impaired glucose tolerance to NIDDM. The San Luis Valley Diabetes Study.

OBJECTIVE: To determine if dietary fat intake measured at a baseline exam in subjects with impaired glucose tolerance (IGT) predicted the subsequent development of non-insulin-dependent diabetes mellitus (NIDDM). RESEARCH DESIGN AND METHODS: Based on an oral glucose tolerance test (OGTT) (World Health Organization criteria), we identified 134 eligible subjects with IGT from a geographically based sample of subjects with no prior history of diabetes. One to three years after the baseline exam, 123 subjects (92%) had a repeat OGTT. Diet was assessed by a 24-h diet recall reported before the baseline OGTT. RESULTS: The mean percentage of energy eaten as fat was 43.4% in 20 people subsequently developing NIDDM compared with 40.6% in 43 people remaining IGT and 38.9% in 60 subjects who subsequently reverted to normal glucose tolerance. In comparing the 20 subjects who developed NIDDM with the 103 who remained IGT or normal, an increase in fat intake of 40 g/day was associated with an increase in risk of NIDDM of 3.4-fold (95% confidence interval [CI] 0.8-13.6) adjusted for energy intake, age, sex, ethnicity, and obesity. The odds ratio increased to sixfold (95% CI 1.2-29.8) after adjustment for fasting glucose, insulin, and 1-h insulin. CONCLUSIONS: Fat consumption significantly predicts NIDDM risk in subjects with IGT after controlling for obesity and markers of glucose metabolism.

Adult↗
PubMed1993

Excess incidence of known non-insulin-dependent diabetes mellitus (NIDDM) in Hispanics compared with non-Hispanic whites in the San Luis Valley, Colorado.

Non-insulin-dependent diabetes mellitus is between two and five times more prevalent among Hispanic Americans than among non-Hispanic whites (NHW). Incidence data for Hispanic populations will help to determine whether this excess prevalence is due to increased incidence, survivorship, or other factors. Incident cases were identified through concurrent surveillance of all local medical practices from 1983 to 1988 in two southern Colorado counties in which the population was 46% Hispanic. All identified subjects were invited for an oral glucose tolerance test. Among the subjects who attended clinic, 83% were confirmed as having diabetes, using WHO criteria. The standardized average annual incidence rates per 1000 for confirmed non-insulin-dependent diabetes, accounting for nonresponse, were 3.7 and 1.6 for Hispanic and NHW males, and 4.5 and 1.2 for Hispanic and NHW females, respectively. The age and nonresponse adjusted rate ratio comparing Hispanics to NHWs was 3.1 (95% CI: 2.3-4.2), indicating a significant excess risk of diabetes incidence for the Hispanic population in southern Colorado. Peak age-specific incidence among Hispanics occurred in persons 50 to 59 years old, a decade earlier than among NHWs. These results are consistent with data from the Mexican-American population in Texas and suggest that the previously observed excess in diabetes prevalence is due to higher incidence rates. The earlier age-specific peak in incidence has also been observed in Mexican-American and American Indian populations, suggesting that risk factors may operate at earlier ages.

Adult↗
PubMed1993

Is the risk of coronary heart disease lower in Hispanics than in non-Hispanic whites? The San Luis Valley Diabetes Study.

A less favorable cardiovascular risk factor profile, but paradoxically lower coronary heart disease mortality and prevalence have been reported for Hispanic men compared to non-Hispanic white men. Since mortality and prevalence data are susceptible to bias, the patterns of coronary heart disease incidence, as well as prevalence and mortality, were investigated in a biethnic Hispanic and non-Hispanic white population of the San Luis Valley in Colorado. Little evidence was found for lower incidence, prevalence, or mortality due to coronary heart disease among Colorado Hispanics without diabetes. The risk of coronary heart disease among diabetic Hispanics appeared, however, to be approximately 50% lower than among non-Hispanic whites, especially in men. Adjustment for selected cardiovascular risk factors (age, gender, diabetes, hypertension, cigarette smoking, body mass index, and high-density lipoprotein cholesterol and triglycerides levels) did not change this ethnic pattern. The plausible explanations of a lower coronary heart disease risk among diabetic Hispanics, compared to non-Hispanic whites, include both biologic mechanisms and artifacts due to deficiencies of mortality classification or differential access to health care. The existing evidence is insufficient to conclude that the risk of coronary heart disease in the general population differs between Hispanics and non-Hispanic whites. The ethnic patterns of coronary heart disease incidence should be investigated further through population-based incidence studies.

Adult↗
PubMed1986

Transfusion-acquired hepatitis A in a premature infant with secondary nosocomial spread in an intensive care nursery.

An outbreak of hepatitis A involving 15 nurses, two premature infants, and the mother of one infant occurred in an intensive care nursery. The infants became infected after receiving blood transfusions from a donor who shortly thereafter experienced symptoms compatible with hepatitis A and was later found to have serologic evidence of acute hepatitis A. Hepatitis was not suspected clinically in the infants but was documented serologically. One of the infants had an ileostomy with liquid intestinal drainage. Her mother and most, if not all, of the nurses acquired hepatitis from this infant. All 15 nurses had contact with this infant, whereas only four nurses had contact with the second infant. The amount of contact nurses had with this infant clearly was related to their risk of infection. Nurses not actually assigned to this infant but who reported some contact had a significantly lower attack rate than those assigned to the infant. Among assigned nurses, those assigned to more than one shift had 4.7 times the risk of acquiring hepatitis than those assigned to one shift only. No specific nursing techniques or personal habits were documented as being significant risk factors in the infected group of nurses.

Adult↗
PubMed1980

Prediction of serum gentamicin concentrations in patients undergoing hemodialysis.

The predictability of a one-compartment pharmacokinetic model for estimating serum gentamicin concentrations in patients undergoing hemodialysis was studied. Nine hemodialysis patients with gram-negative bacillary infections requiring aminoglycoside therapy and with creatinine clearances of less than 1 ml/min were studied. A series of blood samples was assayed by radioimmunoassay to determine serum concentrations after an initial 1.5- to 2.0-mg/kg i.v. dose and throughout the dialysis period. These data were used to predict post-dialysis serum concentrations and post-dialysis doses needed to achieve therapeutic concentrations. The mean apparent volume of distribution for gentamicin was 0.26 +/- 0.06 liter/kg. The mean gentamicin half-life was 31.5 hours before dialysis and 7.6 hours during dialysis. No significant differences were found between predicted and measured peak gentamicin serum concentrations after dialysis; nor were there significant differences for peak serum concentrations obtained with a post-dialysis gentamicin dose (p less than 0.001). Neither the peaks predicted based on the individual patient's pharmacokinetic values nor those based on the average of the patients' pharmcokinetic values were statistically different from measured. The kinetic model developed can be used to determine gentamicin dosing for hemodialysis patients and to determine an average elimination rate constant for a given dialysis apparatus.

Adult↗
PubMedDate not supplied

Setting rates for Medicaid managed behavioral health care: lessons learned.

This paper reviews Tennessee's experience setting, monitoring, and updating capitation rates for Medicaid managed behavioral health care, and draws lessons from those experiences for other states. Our review of assumptions about four components of Tennessee's rate-setting process--data, benefit design, savings expectations, and processes for monitoring and updating rates--suggests that the initial rate established by Tennessee was inadequate, and its inadequacy resulted primarily from the way available information was used to set the rate, rather than from the method of rate setting selected. Tennessee's experiences illustrate how difficult rate setting is and illuminate several key lessons about the rate-setting process.

Behavioral Medicine↗