PubMed Health⌕ Search

Biomedical subjects

M Aickin

Publications and source records attributed to M Aickin.

At least 19 recordsLinked to original sources
PubMed1996

Randomized, double-blinded, placebo-controlled study of effect of wheat bran fiber and calcium on fecal bile acids in patients with resected adenomatous colon polyps.

BACKGROUND: Ongoing epidemiologic and nutritional studies suggest that colorectal carcinogenesis is consistent with complex interactions between genetic susceptibility and environmental and dietary factors. Among the dietary components found to reduce colon cancer risk are high intakes of dietary fiber and calcium. PURPOSE: We designed and conducted a randomized, double-blinded, placebo-controlled trial involving supplementation of the customary dietary intake with fiber and calcium and measurements of fecal bile acids to examine the potential mechanisms by which added dietary interventions might reduce colorectal cancer risk. METHODS: In a randomized, double-blinded, phase II study, we used a factorial design to measure the effects of dietary wheat bran fiber (2.0 or 13.5 g/day) in the form of cereal and supplemental calcium carbonate (250 or 1500 mg/day elemental calcium) taken as a tablet on fecal bile acid concentrations and excretion rates. Measurements were made at base-line randomization (i.e., after a 3-month placebo run-in period using 2.0 g wheat bran fiber plus 250 mg calcium carbonate) and after 3 and 9 months on treatment in a randomly selected 52-patient subsample of the 95 fully assessable study participants who had a history of colon adenoma resection. Concentrations of fecal bile acids, total, primary (i.e., chenodeoxycholic and cholic), and secondary (i.e., deoxycholic, lithocholic, and ursodeoxycholic), were measured in 72-hour stool samples by gas-liquid chromatography. All P values resulted from two-sided tests. RESULTS: All geometric mean fecal bile acid concentrations and excretion rates were lower at 9 months than at 0 months or 3 months on treatment in the high-dose fiber, high-dose calcium, and high-dose fiber/high-dose calcium treatment groups. The high-dose fiber effect at 9 months of supplementation was statistically significant with respect to virtually all geometric mean fecal bile acid concentrations and excretion rates. For example at 9 months versus 0 months, high-dose fiber supplementation caused a reduction in fecal concentrations of total bile acids (52% reduction; P = .001) and deoxycholic acid (48% reduction; P = .003). High-dose calcium supplementation also had a significant, but lower, effect at 9 months versus 0 months on the geometric mean total bile acid (35% reduction; P = .044) and deoxycholic fecal bile acid (36% reduction; P = .052) concentrations. CONCLUSIONS: High-dose wheat bran fiber and calcium carbonate supplements given for 9 months are associated with statistically significant reductions in both total and secondary fecal bile acid concentrations and excretion rates in patients with resected colon adenomas. This study supports the hypothesis that one of the important ways in which a high intake of wheat bran fiber and calcium may reduce the risk of colorectal neoplasia and cancer is by reduction of the concentrations of fecal bile acids. IMPLICATION: Phase III studies of these agents in the prevention of adenoma recurrence are necessary to confirm this hypothesis and have now been initiated at multiple institutions.

Adenomatous Polyposis Coli↗
PubMed1995

Effects of resistance training on regional and total bone mineral density in premenopausal women: a randomized prospective study.

This study was designed to assess the effects of 18 months of resistance exercise on regional and total bone mineral density (BMD) and soft tissue lean mass (STL) in premenopausal women aged 28-39 randomly assigned to an exercise or control group. Twenty-two exercise and 34 control subjects completed the 18-month training study. All subjects were previously inactive and untrained women. Initial, 5-, 12- and 18-month assessments were made of total and regional BMD and total and regional STL using dual energy X-ray absorptiometry. All subjects consumed a 500 mg/day elemental calcium supplement throughout the study. Initial Ca intake without supplement averaged 1,023 mg/day in total sample. Serum levels of bone osteocalcin and dietary assessments using 12 randomly assigned days of diet records were also completed. Muscular strength was assessed from both 1 repetition maximum (RM) testing of 10 weightlifting exercises and by peak torque for hip abduction/adduction and knee extension/flexion. Training increased strength by 58.1% based on 1 RM testing and by 33.8% based on isokinetic testing at 18 months versus baseline. BMD increased significantly above baseline at the lumbar spine for the exercise group at 5 months (2.8%), 12 months (2.3%), and 18 months (1.9%) as compared with controls. Femur trochanter BMD increased significantly (p < 0.05) in the exercise group at 12 months (1.8%) and 18 months (2.0%) but not at 5 months (0.7%) as compared with controls. No changes in total BMD, arm BMD, or leg BMD were found. There was a 20% increase in BGP in the exercise group as compared with controls at 5 months and this difference was maintained throughout the study. For STL, significant increases for total, arm, and leg were found at 5, 12, and 18 months for the exercise group versus control ranging from 1-6% over baseline. These results support the use of strength training for increasing STL and muscular strength with smaller but significant regional increases in BMD in the premenopausal population.

Absorptiometry, Photon↗
PubMed1995

Dieting and "watching" behaviors among adolescent females: report of a multimethod study.

PURPOSE: This study posits a distinction between "watching what you eat" and dieting behaviors in a sample of adolescent females. Findings suggest that the dichotomy of dieter/nondieter fails to capture a range of healthful behaviors practiced by many adolescent girls. METHODS: Anthropologic and nutritional research methods were used in this study. Data were drawn from 1 year of a longitudinal study of food intake and dieting behaviors in a sample of 231 adolescent females. Multiple methods including one ethnographic interview, a survey questionnaire, a telephone interview, and food records were collected from each informant. RESULTS: Although 44% of the girls in this sample reported trying to lose weight on the day of the survey, only 8.6% of the food records reflected dieting days. In interviews, many identified "watching what they eat" as a health-promoting strategy that allowed them to maintain their weight. Analysis of food record data confirmed a trend toward higher intakes of micronutrients. CONCLUSIONS: Research concerned with adolescent weight loss behaviors has focused more on negative than positive health attitudes and behaviors. The present study identified the behavior of "watching" as distinct from dieting. "Watching" was widely utilized by girls in this sample as a way to maintain weight and promote health.

Adolescent↗
PubMed1995

Nutrients, body composition and exercise are related to change in bone mineral density in premenopausal women.

This study determined relationships among total energy intake, nutrient intake, body composition, exercise group status, and annual rates of change (slopes) in bone mineral density in 66 Caucasian premenopausal women (mean age, 34.4 +/- 2.7) taking calcium supplements. Body composition components measured by dual-energy X-ray absorptiometry included fat mass, soft tissue lean mass, and bone mineral density (g/cm2) of total body, spine (lumbar vertebrae 2-4), and three femur sites measured at baseline, 5, 12, and 18 mo. Nutrients were not significant variables in regression models predicting bone mineral density slopes (rates of change) at any femur site. The only significant variable in models predicting Ward's triangle bone mineral density slope was the initial fat mass and, for trochanter, exercise. Significant variables (P < 0.05) in models predicting total body bone mineral density slope included the initial fat mass and fat mass slope plus either vitamin A, carotene, fiber, magnesium, or phosphorus (R2 from 0.31 to 0.25) and fat mass slope plus sodium (R2 = 0.24). The significant variable in the model predicting L2-4 slope was energy intake (R2 = 0.17, P < 0.05). We conclude that nutrient intake, exercise, and body composition are related to bone mineral density rate of change and that relations among these variables vary by bone site.

Absorptiometry, Photon↗
PubMed1995

Risk factors for Barrett's oesophagus: a life history approach to behavioural assessment in the distant past.

Little is known about the aetiology of Barrett's oesophagus, a condition in which columnar epithelium replaces normal squamous epithelium above the juncture of the oesophagus with the stomach. An exploratory retrospective study of males from the Tucson Veteran's Affairs Medical Center (Tucson, AZ, USA), looking at 22 Barrett's cases and 22 controls, was undertaken to: (1) determine whether risk factors previously reported for squamous oesophageal cancer were also potential risk factors for Barrett's oesophagus; and (2) explore which of several retrospectively determined dietary factors would permit maximum discrimination of Barrett's cases from controls. Because of the recognized difficulty with retrospective dietary assessment, an intensive interview-based life history approach was developed to assess behavioural factors throughout adulthood. We examined the dose-response relationship involving questions (1) and (2) separately for subjects with lesions less than or greater than 7 cm in length. A literature-based oesophageal cancer risk factor score (including use of tobacco and intakes of alcohol, fat, vitamin A, linoleic acid and protein) discriminated cases from controls. Alcohol consumption alone discriminated patients with lesions < 7 cm in length from controls, and a more complex risk factor score (including tobacco use, alcohol, fat, fruits and vegetables) discriminated patients with lesions > 7 cm in length from controls.

Adult↗
PubMed1994

Comparative exposure ratios: a non-parametric, multifactor technique for case-control studies.

The odds ratio in a two-by-two table is widely used in case-control studies to measure association between disease and a binary risk factor. In this article we propose a more general measure of association, the comparative exposure ratio (CER), which is the ratio of the number of case-control pairs where the case has greater exposure divided by the number where the control has greater exposure. In simple cases, the CER is an odds ratio or a weighted combination of odds ratios. In more general cases, a CER continues to measure association even when an odds ratio computation is not feasible. Moreover, CERs improve on odds ratios in several ways: they do not require binary risk factors, or a choice of the scale of measurement of continuous risk factors; they make it possible to investigate multiple risk factors simultaneously, without multivariate parametric assumptions; they also can be used to detect patterns that might indicate possible causal pathways. We illustrate how various choices of the definition of 'greater exposure' make the CER a powerful and flexible tool. We give expressions for confidence intervals for CERs, and verify in a pilot simulation that they are valid. Finally, we illustrate with a case-control study of cervical dysplasia how exploratory inference using CERs can be carried out.

Case-Control Studies↗
PubMed1994

Validation of proliferation indices as surrogate endpoint biomarkers.

During the 1990s, research interest in the use of chemopreventive agents to reverse human colon carcinogenesis increased exponentially. In parallel, there has been an increase in the need for putative surrogate endpoint biomarkers (SEBs) of cancer risk. Since the hallmark studies of Lipkin et al. and Terpstra et al., among others, the rate and patterns of rectal mucosal proliferation have been established as intermediate biomarker endpoints for colon cancer risk, modulated by potential chemopreventive agents including calcium, wheat bran fiber, and nutritional stress diets. Researchers rely heavily on these rectal mucosal proliferation indices as surrogate endpoints to evaluate the relative efficacy of various chemopreventive intervention strategies. Standardization through quality control/quality assurance (QC/QA) programs which continuously validate the accuracy, reproducibility, and variability of these indices is increasingly needed. Along with many others, we have attempted to validate 3H-thymidine and bromodeoxyuridine labeling indices in rectal mucosal biopsies as reliable SEBs. In this manuscript we outline a series of QC/QA steps that can be followed in the validation process for new as well as "old" biomarkers prior to their use as primary efficacy surrogate endpoints for chemopreventive agent intervention trials.

Adenoma↗
PubMed1994

If there is gold in the labeling index hills, are we digging in the right place?

Surrogate endpoint biomarkers (SEBs) are a necessary tool for cancer chemoprevention studies. However, the efficiency gain from using an SEB is purchased at a price. SEBs need to go through a developmental process, in which their behavior is understood in detail, before they can be used broadly in chemoprevention work. Examples of problems that need to be overcome are presented for labeling indices of cell proliferation. Since literature-based meta-analyses are not feasible for SEBs, a data archive is proposed in order to strengthen the development phase by pooling data across studies.

Anticarcinogenic Agents↗
PubMed1993

Resistance exercise training is associated with decreases in serum low-density lipoprotein cholesterol levels in premenopausal women.

BACKGROUND: Aerobic exercise training is associated with reduced serum concentrations of triglycerides, increased concentrations of high-density lipoprotein cholesterol, and minimal changes in serum levels of total cholesterol or low-density lipoprotein cholesterol. There are few data on the effects of resistance exercise on blood lipid levels. METHODS: Premenopausal women were randomly assigned to a supervised resistance exercise training program (n = 46) or a control group (n = 42) for 5 months. Serum was analyzed for levels of total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglycerides. Body composition and dietary intake were also measured. RESULTS: The exercise group showed a 0.33 +/- 0.03-mmol/L (mean +/- SE) decrease in total cholesterol level and a 0.36 +/- 0.001-mmol/L decrease in low-density lipoprotein cholesterol level that was significantly different from the control group. No significant changes were noted in serum high-density lipoprotein cholesterol or triglyceride levels in either group. Changes in body composition showed no significant correlations with changes in total cholesterol or low-density lipoprotein cholesterol. There were no significant differences in nutrient intake between the groups. CONCLUSION: In healthy, premenopausal women, with normal baseline lipid profiles, 5 months of resistance exercise training was associated with significant decreases in serum total cholesterol and low-density lipoprotein cholesterol concentrations.

Adult↗
PubMed1992

The effectiveness of adherence intervention in a colon cancer prevention field trial.

BACKGROUND: Adherence interventions were implemented in a 1-year community-based colon cancer prevention clinical trial (n = 110) using wheat bran fiber and calcium dietary supplements. The adherence promotion strategy was guided by a theoretical model. METHODS: The adherence intervention contains both a generalized portion given to all participants and an individualized portion given to marginal (50-74% intake) and low (under 50% intake) adherers. A regression model was employed to assess the effectiveness of the interventions both at the first intervention and at subsequent times. RESULTS: The Health Behavior in Cancer Prevention Model-based adherence promotion intervention was associated with retention of participants, both during the run-in period and after randomization (P = 0.05); and maximization of the percentage of the 13.5-g recommended fiber supplement consumed during the trial (92.5%). The positive effects of the adherence intervention were greater with first-time nonadherers and the control group than with the experimental group. The high-fiber group had notably more biological GI effects from the increased fiber intake, more preexisting comorbidities, and lower perceived cognitive and physical health status. CONCLUSIONS: Randomized participants had excellent adherence overall. Retention rates in the trial were better than would be expected without the adherence intervention, especially among those participants who may have been at higher risk for dropping out of the study. This suggests that a systematic, theoretically based adherence strategy should be further tested in clinical trial settings in which lower adherence is a problem.

Aged↗
PubMed1992

Reasons related to adherence in community-based field studies.

This study identified participants' reasons for good, marginal or poor adherence, or withdrawing from community-based clinical studies using a dietary and/or drug intervention. Adults aged 48-75 years participated in one of three studies related to decreasing colon polyp recurrence. Qualitative data from progress notes (N = 675) and end-of-study evaluations (N = 87) were coded using constant comparative analysis with 100% content validity panel agreement. Most common reasons for non-adherence were barriers such as side-effects, interference with vacation plans, unrelated illness, forgetting and competing outside stressors. Participation motivators were benefits such as altruism, medical benefits, free service and staff rapport. Findings supported the Health Behavior in Cancer Prevention model-based approach to adherence interventions and provided directions for adherence promotion in future community-based clinical studies.

Aged↗
PubMed1992

Assessment of the spatial occurrence of childhood leukaemia mortality using standardized rate ratios with a simple linear Poisson model.

Reports of a suspected cluster of childhood leukaemia cases in West Central Phoenix have led to a number of epidemiological studies in the geographical area. We report here on a death certificate-based mortality study, which indicated an elevated rate ratio of 1.95 during 1966-1986, using the remainder of the Phoenix standard metropolitan statistical area (SMSA) as a comparison region. In the process of analysing the data from this study, a methodology for dealing with denominator variability in a standardized mortality ratio was developed using a simple linear Poisson model. This new approach is seen as being of general use in the analysis of standardized rate ratios (SRR), as well as being particularly appropriate for cluster investigations.

Adolescent↗
PubMed1991

A criterion for the adequacy of a simple design when a complex model will be used for analysis.

Sample size computations for relatively complex analyses, such as multiple linear regression, are made difficult by the fact that various quantities that are required by the usual formulas will not be available until the completion of the trial. This fact makes sample size justifications in the design phase of the trial more tenuous than one would like. Here it is shown that for randomized clinical trials it usually suffices to compute sample size on the basis of a simpler model for the analysis than that which will actually be used. Therefore, standard formulas generally provide valid, although possibly inefficient, sample size determinations.

Clinical Trials as Topic↗
PubMed1991

Reduction of murine cutaneous UVB-induced tumor-infiltrating T lymphocytes by dietary canthaxanthin.

The effect of dietary canthaxanthin, retinyl palmitate, or their combination on the tumor-infiltrating T-lymphocyte response (T-TIL) in de novo murine ultraviolet type B irradiation-induced tumors was investigated to elucidate potential mechanisms of action of these compounds. We found that dietary canthaxanthin greatly reduced the number of tumor-infiltrating helper/inducer, suppressor/cytotoxic, and interleukin-2 receptor-positive T lymphocytes and also observed a concomitant statistically significant increase in tumour incidence in canthaxanthin-fed animals. The addition of retinyl palmitate to the canthaxanthin diet ameliorated this negative effect on TIL and the development of skin tumors. We conclude that dietary retinyl palmitate and canthaxanthin can modulate the host T-cell immune response within a growing tumor and may affect tumorigenicity.

Animals↗
PubMed1991

Estimation of population denominators for public health studies at the tract, gender, and age-specific level.

In epidemiologic and public health studies of disease incidence in geographic subpopulations, attention is properly directed toward the ascertainment of accurate numerators. Population or person-years denominators are generally given less consideration, under the assumption that estimates produced by sources other than the state health department are sufficiently accurate. Here, we report our experience in estimating person-years denominators in the highly urbanized, rapidly expanding population of Maricopa County, Arizona. The usual sources of population estimates were found to be of little use for public health purposes, and so we report on a method for obtaining smoothed person-years figures that can accurately reflect population acceleration which varies from one time period to another. Our method is to regress the logarithm of census enumerations on quadratic or tertic polynomials in time. We describe how differential reliability of census figures can be incorporated into our procedure, and how the problem of missing census data can be handled by an iterated regression method. Our evidence suggests that the logarithmic regression model works well, even in the face of rapid and erratic population growth or decline.

Adolescent↗
PubMed1990

Lack of impact of therapy on extent of Barrett's esophagus in 67 patients.

Sixty-seven patients with Barrett's esophagus have been prospectively followed over an average of 36 months (range 6 to 76 months) with standardized endoscopic observation and biopsies of the length of columnar epithelium. The initial length of Barrett's epithelium ranged from 1 to 16 cm, mean 5.5 cm. Specialized columnar epithelium was present in 64 of the 67 patients. Patients were treated predominantly with H2-receptor blocker therapy to relieve symptoms. Eighty-two percent of patients had less than a 1-cm change in length per year. The mean rate of change of length was -0.093 cm per year. These results confirm in a relatively large, prospective study that standard antireflux therapy for Barrett's esophagus does not result in consistent reduction in the extent of Barrett's epithelium over a three-year interval.

Adult↗
PubMed1990

Cumulative reduction of primary skin tumor growth in UV-irradiated mice by the combination of retinyl palmitate and canthaxanthin.

The effects of dietary supplementation with retinyl palmitate, canthaxanthin, or the combination of both, on photocarcinogenesis was determined in pigmented C3H/HeN mice. The basal diet was the American Institute of Nutrition Diet 76A, to which was added 120 IU of retinyl palmitate per g diet, 1% canthaxanthin, or the combination of both. Administration of the diets began 18 weeks before the first UVB radiation (280-320 nm) treatment and continued throughout the study. The UV source was a bank of 6 Westinghouse FS40 lamps which delivered to the mice a total dose of 9.9 x 10(5) J/m2, delivered over 24 weeks. These diets significantly reduced the tumor burden per mouse induced by UV irradiation, however they did not influence tumor incidence. The combination of retinyl palmitate plus canthaxanthin was more effective than either agent alone at reducing autochthonous tumor growth, a result which has not been previously reported.

Animals↗