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Biomedical subjects

J D Graham

Publications and source records attributed to J D Graham.

At least 19 recordsLinked to original sources
PubMed1996

Progesterone receptor A and B protein expression in human breast cancer.

The human progesterone receptor (PR) is a ligand-activated nuclear transcription factor which mediates progesterone action in target tissues. Two PR proteins, PR A (81-83 kDa) and PR B (116-120 kDa), have been described and different physiological activities ascribed to each on the basis of in vitro studies, suggesting that their ratio of expression may control progesterone responsiveness in target cells. Presence of PR in breast tumors is an important indicator of likely responsiveness to endocrine agents. However, the relative expression of PR A and B in breast cancer has not been described and its clinical significance has not been addressed. We have examined the expression of PR A and B in PR-positive breast tumors and found that while in most tumors PR A and B were expressed in similar amounts there was a broad overall distribution of PR A:B ratio which deviated significantly from a normal log distribution with tumors containing a PR A:B ration greater than 4 being over-represented in the group. Linear regression analysis revealed that high PR A:B ratios, in general, derived from a low concentration of PR B rather than high expression of PR A. PR A:B protein ratios were not correlated with the age of the patient or with total PR concentration. A third PR protein band (PR 78 kDa) was detected which comprised greater than 20% of total PR protein in a quarter of the tumor samples examined. The characteristics of tumors containing PR 78 kDa were not different from the overall group. In summary, in PR-positive breast tumors the ratio of expression of PR A and B proteins is close to unity as is seen in a number of other progestin target tissues. However, a significant proportion of tumors expressed very low levels of PR B and a consequently high PR A:B ration. Although the clinical consequence of this observation is not known, the in vitro findings that PR A may act as a repressor for PR B suggests that tumors containing primarily PR A may identify a subset of patients with low or aberrant response to endocrine agents.

Adolescent↗
PubMed1996

Economic evaluation of HIV prevention programs.

Program managers and policy makers need to balance the costs and benefits of various interventions when planning and evaluating HIV prevention programs. Resources to fund these programs are limited and must be used judiciously to maximize the number of HIV infections averted. Economic evaluation studies of HIV prevention interventions, which we review and critique here, can provide some of the needed information. Special emphasis is given to studies dealing with interventions to reduce or avoid HIV-related risk behaviors. Ninety-three cost-benefit, cost-effectiveness and cost-utility analyses were identified overall. However, only 28 dealt with domestic, behavior change interventions; the remainder focused on screening and testing without prevention counseling, and on care and treatment services. There are compelling demonstrations that behavioral interventions can be cost-effective and even cost-saving. The threshold conditions under which these programs can be considered cost-effective or cost-saving are well defined. However, several important intervention types and multiple key populations have been unstudied. Research in these areas is urgently needed.

Adolescent↗
PubMed1996

Effects of previous grazing treatment and consumption of locoweed on liver mineral concentrations in beef steers.

Twelve Hereford steers (average BW = 231 kg) that had previously grazed native rangeland (Range) or irrigated winter wheat pasture (Wheat) were allowed to graze locoweed-infested rangeland from April 1 to June 9, 1994 (six steers/previous grazing treatment). Relative consumption level of locoweed and other forage classes was measured as observed bites per steer. Liver biopsy and whole blood samples were obtained from each steer before and after grazing. Liver samples were analyzed for several minerals by inductively coupled plasma-atomic emission spectroscopy, and whole blood samples were analyzed for Se. Liver concentrations of Ba (P < .001), Cd (P < .001), Ca (P < .01), Cr (P < .01), Ni (P < .001), Na (P < .01), and V (P < .001) were greater and concentrations of Mn (P < .09), P (P < .01), and K (P < .07) were less in Wheat than in Range steers. Liver concentrations of Fe, Mg, S, and Zn and whole blood Se concentrations did not differ (P > .10) between the two groups. Liver concentrations of Cr (P < .04) and Mn (P < .001) were less, and Fe concentrations were greater (P < .01), in samples taken after grazing than in samples taken before grazing of locoweed-infested range. Whole blood Se concentrations decreased (P < .01) from the beginning to the end of the grazing period, but this effect was not related (P > .15) to locoweed consumption. Changes in liver concentrations of minerals were compared relative to consumption levels of all forage classes in the locoweed-infested range. Liver concentrations of Cu decreased (r2 = .45; P < .02) as the percentage of bites consumed as locoweed increased, but concentrations after grazing locoweed-infested range were still within normal ranges. Changes in liver concentrations of other minerals were not related (P > .15) to consumption of locoweed. These data indicate that previous grazing history can have significant effects on liver mineral stores and that, under our conditions, consumption of locoweed by grazing beef steers altered liver Cu concentrations. Toxic effects of locoweed consumption would likely occur before Cu deficiency would be induced by grazing locoweed-infested range; hence, supplementation of Cu would seem unlikely to alter the course of locoweed toxicosis.

Animal Feed↗
PubMed1995

Preferential stimulation of human progesterone receptor B expression by estrogen in T-47D human breast cancer cells.

Human progesterone receptor (PR) expression is controlled by two promoter regions giving rise to transcripts encoding PR A and B proteins. It is unknown whether estrogen and progesterone, the major physiological modulators of PR expression, exert their effects equally on the PR promoters. The aim of this study was to analyze estrogen and progestin effects on PR promoters, PR-encoding transcripts, and PR A and B proteins in T-47D human breast cancer cells. The progestin ORG 2058 caused a prolonged decrease in transcription of the PR gene and also abrogated estrogen stimulation of PR transcription. Estradiol (E2) treatment increased the activity of the B but not the A promoter transfected into T-47D cells. ORG 2058 had no effect on the basal or E2-stimulated activity of either promoter. E2 caused a preferential increase in transcripts derived from promoter B, whereas progestins decreased the levels of all PR transcripts. E2 preferentially increased the concentration of the PR B protein and caused a decrease in the PR A/B ratio. This demonstration that estrogen and progestin independently control the synthesis of transcripts arising from the PR promoters and that estrogen alters the cellular PR A/B ratio provides possible mechanisms underlying the cell and tissue specificity of PR regulation.

Breast Neoplasms↗
PubMed1995

Characterization of progesterone receptor A and B expression in human breast cancer.

The human progesterone receptor (PR) is a ligand-activated nuclear transcription factor that mediates progesterone action in target tissues. Two PR proteins, PR-A (M(r) 81,000-83,000) and PR-B (M(r) 116,000-120,000), have been described and different physiological activities ascribed to each on the basis of in vitro studies, suggesting that their ratio of expression may control progesterone responsiveness in target cells. Presence of PR in breast tumors is an important indicator of likely responsiveness to endocrine agents. However, the relative expression of PR-A and B in breast cancer has not been described, and its clinical significance has not been addressed. Expression of PR-A and B was measured by immunoblot analysis of 202 PR-positive human breast tumor cytosols. The ratio of expression of the two PR proteins (PR-A/B) ranged from 0.04 to 179.3. The median PR-A/B ratio was 1.26, and 61.4% of samples had PR-A/B ratios between 0 and 2. PR-A/B ratios deviated significantly from a normal log distribution; tumors containing a PR-A/B ratio greater than 4 were overrepresented in the group. Linear regression analysis revealed that high PR-A/B ratios, in general, derived from a low concentration of PR-B rather than high expression of PR-A. PR-A/B protein ratios were not correlated with the age of the patient or with total PR concentration. A third PR protein band (PR78kDa) was detected in a number of samples and comprised greater than 20% of total PR protein in 52 (25.7%) of the 202 tumor samples examined. The range or frequency distribution of PR-A/B ratios in samples containing PR78kDa was not different to the overall group. In summary, in PR-positive breast tumors, the ratio of expression of PR-A and B proteins is close to unity, as is seen in a number of other progestin target tissues. However, a significant proportion of tumors expressed very low levels of PR-B and a consequently high PR-A/B ratio. Although the clinical consequence of this observation is not known, the in vitro findings that PR-A may act as a repressor of PR-B suggest that tumors containing primarily PR-A may identify a subset of patients with low or aberrant response to endocrine agents.

Biopsy↗
PubMed1995

Historical perspective on risk assessment in the federal government.

This article traces the evolution of risk assessment as an essential analytical tool in the federal government. In many programs and agencies, decisions cannot be made without the benefit of information from risk assessment. Although this analytical tool influences important public health and economic decisions, there is widespread dissatisfaction with the day-to-day practice of risk assessment. The article describes the sources of dissatisfaction that have been voiced by scientists, regulators, interest groups and ordinary citizens. Problems include the use of arbitrary exposure scenarios, the misuse of the 'carcinogen' label, the excessive reliance on animal cancer tests, the lack of formal uncertainty analysis the low priority assigned to noncancer endpoints, the poor communication of risk estimates and the neglect of inequities in the distribution of risk. Despite these limitations, the article argues that more danger rests in efforts to make decisions without any risk assessment. Recent Congressional and Administration interest in risk assessment is encouraging because it offers promise to learn from past mistakes and set in motion steps to enhance the risk assessment process.

Animals↗
PubMed1995

Delaney reform.

Explore the source record for details and available documents.

Animals↗
PubMed1995

Who's in the car? Passengers as potential interveners in alcohol-involved fatal crashes.

This article assesses the promise of motor vehicle passengers as interveners to prevent drinking and driving. It describes data from the U.S. Fatal Accident Reporting System (FARS), which indicate that most alcohol-involved fatally injured drivers (70% of males, 66% of females) were not accompanied by "adult" passengers (16 or older), and alcohol involvement among those passengers present appears to be high (80%). Nonetheless, in approximately 5% to 10% of cases it appears that sober or relatively "unimpaired" passengers could have served as interveners in alcohol-involved driving incidents. Passenger interveners may hold the most promise among teenagers, where passengers in general and unimpaired passengers in particular appear to be most prevalent.

Accidents, Traffic↗
PubMed1995

Five-hundred life-saving interventions and their cost-effectiveness.

We gathered information on the cost-effectiveness of life-saving interventions in the United States from publicly available economic analyses. "Life-saving interventions" were defined as any behavioral and/or technological strategy that reduces the probability of premature death among a specified target population. We defined cost-effectiveness as the net resource costs of an intervention per year of life saved. To improve the comparability of cost-effectiveness ratios arrived at with diverse methods, we established fixed definitional goals and revised published estimates, when necessary and feasible, to meet these goals. The 587 interventions identified ranged from those that save more resources than they cost, to those costing more than 10 billion dollars per year of life saved. Overall, the median intervention costs $42,000 per life-year saved. The median medical intervention cost $19,000/life-year; injury reduction $48,000/life-year; and toxin control $2,800,000/life-year. Cost/life-year ratios and bibliographic references for more than 500 life-saving interventions are provided.

Cost-Benefit Analysis↗
PubMed1994

Use of probabilistic expert judgment in uncertainty analysis of carcinogenic potency.

A new approach to characterizing the state of knowledge about carcinogenic potency is described. In this approach, the carcinogenic risk posed by a specific dose is characterized by a probability distribution, indicating the relative likelihood of different risk estimates. The approach utilizes expert judgment and a probability tree and is illustrated in a case study of chloroform exposure. Experts in cancer biology/toxicology, pharmacokinetics, and dose-response modeling were identified by a panel of science-policy specialists. In a workshop, experts reviewed the chloroform data, received training in probability elicitation, and constructed a consensual probability tree based on biological theories of cancer causation. Distributions of carcinogenic risk were developed based on the probability tree, chloroform data, judgmental probabilities provided by the experts, and classical statistical techniques. Risk distributions varied considerably between experts, with some predicting essentially no risk from 100 ppb chloroform in drinking water while other have at least some probability on risks generally considered of regulatory significance. Estimated human risk was much lower when extrapolating from liver tumors in animals than from kidney tumors. Issues of scientific disagreement leading to different risk distributions between experts are discussed. The resulting risk distributions are compared to standard EPA risk calculations for the same exposure scenario as well as to the expert judgement of epidemiologists about cancer risks of chlorinated drinking water. Issues in combining expert judgments are discussed, and several alternative methods are presented. Strengths and weaknesses of the distributional approach are discussed.

Animals↗
PubMed1994

A distributional approach to characterizing low-dose cancer risk.

Since cancer risk at very low doses cannot be directly measured in humans or animals, mathematical extrapolation models and scientific judgment are required. This article demonstrates a probabilistic approach to carcinogen risk assessment that employs probability trees, subjective probabilities, and standard bootstrapping procedures. The probabilistic approach is applied to the carcinogenic risk of formaldehyde in environmental and occupational settings. Sensitivity analyses illustrate conditional estimates of risk for each path in the probability tree. Fundamental mechanistic uncertainties are characterized. A strength of the analysis is the explicit treatment of alternative beliefs about pharmacokinetics and pharmacodynamics. The resulting probability distributions on cancer risk are compared with the point estimates reported by federal agencies. Limitations of the approach are discussed as well as future research directions.

Animals↗
PubMed1994

Social supports as a determinant of community-based care utilization among rehabilitation patients.

OBJECTIVE: We determine the extent to which noninstitutionalized long-term care patients receive assistance from family members and friends, and evaluate the effect of this assistance on use of outpatient rehabilitative and personal care services. DATA SOURCES AND STUDY SETTING: Over 12 months, primary data were collected from 289 patients in noninstitutional settings after inpatient rehabilitation at three Boston-area rehabilitation hospitals. Data on patients' acute and rehabilitative stays were obtained from medical record reviews. Patients provided primary data on sociodemographics, living arrangements, social supports, functional status, health behaviors, life events, and use of outpatient services during the study period. The latter was verified and service charge data obtained from the care providers. STUDY DESIGN: The study was longitudinal and observational. Patient-provided information was obtained at one, six, and twelve months postdischarge. ANALYTIC METHODS: Multivariate Tobit regression was used to evaluate the effect of social supports on patients' use of rehabilitative and personal care services, controlling for sociodemographics and functional status. Service use was measured as charges incurred during the 12-month study period. PRINCIPAL FINDINGS: Results confirm the primary role of family and friends in providing daily personal care and identify the availability of that support as a key determinant of expenditures on community-based personal care services. Social supports do not predict outpatient rehabilitative service use. CONCLUSIONS: Differing eligibility criteria seem appropriate for outpatient rehabilitative and personal care services. The current emphasis on functional status in determining rehabilitative service eligibility appears appropriate; but we find that considering patients' social supports would be both meaningful and appropriate in determining personal care service eligibility. This approach would avert the expense of making personal care services universally available, while facilitating assistance for patients whose functional and social status put them at increased risk of institutional placement.

Activities of Daily Living↗
PubMed1993

A new method for making interstate comparisons of highway fatality rates.

Highway fatality rates vary significantly among jurisdictions. Before attributing these variations to policy differences, it is important to account for exogenous factors (e.g. weather) that are beyond the control of policy makers. A new method is developed to identify states that are doing better or worse than expected. The method is applied to the 48 contiguous American states using highway fatality data for the years 1975 to 1986. A fixed effects linear model is used to estimate the fatality rate for each state, taking into account exogenous factors. Results indicate that many states have higher or lower fatality rates than is expected based on a ranking of states according to crude fatality rates. Policy implications are discussed.

Accidents, Traffic↗
PubMed1993

Fractionated stereotactic external beam radiotherapy in the management of brain metastases.

24 patients with 28 brain metastases were treated with fractionated stereotactic radiotherapy (SRT). Doses ranged from 10 Gy in two fractions to 20 Gy in two fractions. 13 patients received SRT boost after whole brain radiotherapy (WBRT), 5 were treated with SRT alone and 6 were treated at the time of recurrence following WBRT. The median progression-free survival at the treated site was 18 months and the median survival was 18 months. All patients were treated without admission to hospital. Toxicity of fractionated SRT was minimal and patients treated without WBRT did not suffer significant alopecia. Fractionated SRT offers a non-toxic non-invasive alternative to excision surgery in patients with solitary brain metastases. The optimum fractionation schedule and the role of whole brain irradiation remain to be determined.

Adult↗
PubMed1993

The challenge of risk characterization: current practice and future directions.

Risk characterization is perhaps the most important part of risk assessment. As currently practiced, risk characterizations do not convey the degree of uncertainty in a risk estimate to risk managers, Congress, the press, and the public. Here, we use a framework put forth by an ad hoc study group of industry and government scientists and academics to critique the risk characterizations contained in two risks assessments of gasoline vapor. After discussing the strengths and weaknesses of each assessment's risk characterization, we detail an alternative approach that conveys estimates in the form of a probability distribution. The distributional approach can make use of all relevant scientific data and knowledge, including alternative data sets and all plausible mechanistic theories of carcinogenesis. As a result, this approach facilitates better public health decisions than current risk characterization procedures. We discuss methodological issues, as well as strengths and weaknesses of the distributional approach.

Air Pollutants↗