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Biomedical subjects

J D Graham

Publications and source records attributed to J D Graham.

At least 73 records · Page 4Linked to original sources
PubMed1992

Poorer is riskier.

To examine the relationship between economic well being and health status, two economic concepts were explored: the permanent-income hypothesis and the transitory-income hypothesis. A regression analysis of time-series mortality data for the period of 1950-1988 was conducted. The regression results indicated that the total mortality rate is negatively associated with permanent income and positively associated with the transitory income. Results are also reported for the 8 major causes of death in the United States. The implications for risk analysis are discussed.

Health Status↗
PubMed1992

Re-irradiation of soft-tissue sarcoma.

Re-irradiation for local recurrence of malignancy after radical radiotherapy is of proven benefit at head and neck sites but has seldom been used elsewhere. This paper reports a series of 10 patients re-irradiated with external-beam techniques for local recurrence of soft-tissue sarcoma of the limb and limb girdle following initial limb conserving management with surgery and radiotherapy (dose range 33-60 Gy). Median survival was 14 months following re-treatment. Two cases received treatment with high-energy electrons and the rest with megavoltage photons. Five patients re-treated with radical intent (dose range 40-60 Gy) had a median survival of 36 months and median recurrence-free survival of 16 months. All five patients treated palliatively (dose range 12-50 Gy) have died, although two demonstrated local control until death. Acute reactions were not severe. Radionecrosis was seen in one patient who was re-irradiated twice (total dose 145 Gy) and subsequently required amputation. One other case required amputation for persistent local disease, but in the remaining eight, limb conservation was achieved. Re-irradiation of soft-tissue offers good local control and may avoid amputation.

Adult↗
PubMed1992

Early aspects of locoweed toxicosis and evaluation of a mineral supplement or clinoptilolite as dietary treatments.

Sixteen crossbred beef heifers were used to determine the efficacy of serum clinical profiles as diagnostic tools for detection of early stages of locoweed toxicity and to test the ability of two mineral supplements for prevention or therapy of toxicosis. Dietary treatments were (DM basis) 1) 100% sorghum sudangrass hay, 2) 80% sorghum sudangrass hay:20% locoweed, 3) 80% sorghum sudangrass hay:20% locoweed plus 100 g of Silent Herder Mineral Mix (a mineral supplement reported to alleviate locoweed toxicity), and 4) 80% sorghum sudangrass hay:20% locoweed plus 100 g of clinoptilolite (a natural zeolite clay). Diets were fed at 1.5% of BW for 28 d, after which heifers had ad libitum access to sorghum sudangrass hay for 14 d. Jugular blood was sampled before feeding every 7 d, and at 2, 4, 6, and 8 h after feeding on d 28. Compared with controls, heifers fed locoweed had elevated (P less than .01) serum alkaline phosphatase activities from d 7 through 35. On d 42, alkaline phosphatase activities in heifers previously fed locoweed were lower (P less than .05) than in control heifers. Serum glutamic oxaloacetic transaminase activities were elevated (P less than .01) in heifers fed locoweed from d 7 through 42 compared with control heifers. In heifers fed locoweed, serum Fe concentrations were less (P less than .01) on d 7 through 28, but no treatment effects were noted (P greater than .10) on d 35 or 42.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline Phosphatase↗
PubMed1991

A comparison of techniques for stereotactic radiotherapy by linear accelerator based on 3-dimensional dose distributions.

In order to establish the appropriate beam arrangement for use in stereotactic radiotherapy using a linear accelerator, dose volume distributions were calculated for a number of spherical targets in a head phantom and assessment was made by dose sparing of normal tissue outside the target volume. Using a single isocentre, fixed beam arrangements were compared with single and multiple non-coplanar isocentric arc rotations at target sizes from 10 to 55 mm diameter on a 6 MV Philips linear accelerator. From the dose-volume histograms produced, an arrangement of 3 or 4 arcs of rotation proved most suitable, in terms of sparing of normal tissue outside the target volume to high dose irradiation, across the range of target sizes studied. There was little further benefit with increasing the number of arcs beyond this. At target sizes greater than 20 mm diameter an arrangement of 6 static non-coplanar beams achieved sparing equivalent to multiple arc rotations and may have considerable advantages in the treatment of irregular volumes where customised beam shaping could be employed.

Humans↗
PubMed1991

A non-invasive, relocatable stereotactic frame for fractionated radiotherapy and multiple imaging.

A non-invasive relocatable stereotactic frame has been developed for fractionated stereotactic external beam radiotherapy (SRT) by linear accelerator. Fixation is via the upper dentition and tests of repositioning have shown mean antero-posterior and lateral displacements of 1.0 mm. The relocatable frame allows accurate 3-dimensional target localisation by CT, MRI, PET and cerebral angiography and precise isocentric positioning for radiotherapy. This method of immobilisation is ideal for fractionated SRT as well as for other techniques requiring high precision localisation and treatment delivery.

Animals↗
PubMed1991

General deterrence of drunk driving: evaluation of recent American policies.

A testable hypothesis of deterrence theory is that efforts to increase the expected cost of criminal activity by increasing the threat of punishment should, other things being equal, reduce the crime rate. In this paper, we examine whether the incidence of drinking and driving is responsive to escalation of the punitive threat. The recent national campaign against drunk driving provides a natural experiment in which to test the predictions of deterrence theory. Using state level data over the 1975-1986 period, we report no conclusive evidence that any specific form of punitive legislation is having a measurable effect on motor vehicle fatalities. We report suggestive evidence that multiple laws designed to increase the certainty of punishment (e.g., sobriety checkpoints and preliminary breath tests) have a synergistic deterrent effect. The most striking finding is that mandatory seat belt use laws and beer taxes may be more effective at reducing drunk driving fatalities than policies aimed at general deterrence.

Accidents, Traffic↗
PubMed1991

Predicting EPA's forthcoming CO standards in light of new clinical evidence.

For the past several years, the EPA has been monitoring clinical studies on the adverse health effects of heart patients' exposure to carbon monoxide. This paper examines the impact of three such studies (including the multi-center CO study organized by the Health Effects Institute) on the forthcoming EPA standards for carbon monoxide. Eleven peer-nominated specialists with expertise in environmental science and public policy were interviewed according to a specific protocol. Overall, the experts felt that the HEI study would receive greater weight than the other two studies in the regulatory process for a variety of technical reasons. Weighting each expert opinion equally, we conclude that there is about a 0.69 probability that the CO standards will be retained at their present levels, a 0.28 probability that the standards will be tightened, and a 0.03 probability that the standards will be relaxed. When asked to imagine that the HEI data were never collected and then asked to reassess their probability judgments, the mean probability judgment that the standards will be relaxed rose to 0.11, while the mean probability judgment that the standards will be tightened fell to 0.20. A modest degree of variability in expert opinion is reported in the paper. While the HEI study may receive relatively great weight in the regulatory process, it increases only slightly the probability that EPA's CO standards will be changed.

Angina Pectoris↗
PubMed1990

An estimate of the lifesaving benefit of child restraint use legislation.

This paper presents the first econometric estimate of the lifesaving benefit of automobile child restraint use legislation. In contrast to previous econometric analyses of traffic safety regulations, modified count data models are employed to account for the rarity of childhood fatalities. Results of the modeling suggest that legislation reduces childhood car-occupant fatalities by 39% for infants, and 30% among toddlers. A simple simulation indicates that such legislation is currently saving the lives of about 160 children per year in the United States.

Accidents, Traffic↗
PubMed1990

Selecting experimental data for use in quantitative risk assessment: an expert-judgement approach.

In many cancer risk assessments the experimental data used in statistical modeling are selected by applying generic guidelines. The guidelines exclude use of some types of experimental data and often appear arbitrary since rules rather than scientific judgments guide selection of data. This paper implements an alternative approach in which data are selected based on the judgments of practicing scientists. Eight such scientists were identified through an explicit selection procedure to help select data for use in a dose-response assessment of formaldehyde. Judgements about appropriate data sets were then elicited in personal interviews using a formal interview protocol. Appropriate data sets were fit to the multistage model and used as the basis for low-dose extrapolation. Low-dose risk estimates are shown to be sensitive to the selection of data, especially the treatment of benign tumors. The recommendations of the experts also differ in some respects from the choices made in previously published risk assessments. This suggests that scientific judgement may be an appropriate method to augment guidelines when a broad range of data is available. The paper argues that the expert judgment approach has some advantages that are worth considering.

Air Pollutants↗
PubMed1989

The role of lymphography in the management of carcinoma of the endometrium.

In order to assess the role of lymphography in the postoperative management of carcinoma of the endometrium, 57 consecutive cases were analysed retrospectively. Forty-eight patients had undergone definitive surgery and bipedal lymphography was performed in 41 cases (85%). Unilateral pelvic lymphadenopathy was detected in three cases (7%); two stage I, one stage II. In no case did the result of lymphography alter management, based on histological criteria, with either intracavitary radiotherapy alone or in combination with external beam therapy to the pelvis. In a short median follow-up of 11 months (range 2-19 months), four cases have relapsed but all had normal lymphography at initial postoperative staging. Bipedal lymphography has no role in the routine management of carcinoma of the endometrium.

Adult↗
PubMed1988

Expert scientific judgment and cancer risk assessment: a pilot study of pharmacokinetic data.

When high-dose tumor data are extrapolated to low doses, it is typically assumed that the dose of a carcinogen delivered to target cells is proportional to the dose administered to test animals, even at exposure levels below the experimental range. Since pharmacokinetic data are becoming available that in some cases question the validity of this assumption, risk assessors must decide whether to maintain the standard assumption. A pilot study of formaldehyde is reported that was undertaken to demonstrate how expert scientific judgment can help guide a controversial risk assessment where pharmacokinetic data are considered inconclusive. Eight experts on pharmacokinetic data were selected by a formal procedure, and each was interviewed personally using a structured interview protocol. The results suggest that expert scientific opinion is polarized in this case, a situation that risk assessors can respond to with a range of risk characterizations considered biologically plausible by the experts. Convergence of expert opinion is likely in this case of several specific research strategies ar executed in a competent fashion. Elicitation of expert scientific judgment is a promising vehicle for evaluating the quality of pharmacokinetic data, expressing uncertainty in risk assessment, and fashioning a research agenda that offers possible forging of scientific consensus.

Biological Availability↗
PubMed1980

The mechanism of action of delta 9-tetrahydrocannabinol on body temperature in mice.

The effect of delta 9-tetrahydrocannabinol (delta 9-THC) on body temperature of the mouse was studied. A dose-response relationship (5-100 mg/kg) for the hypothermic effect of delta 9-THC was seen. The investigation as to the mechanism underlying the hypothermic action of delta 9-THC was also investigated. The relatively specific dopamine antagonist haloperidol potentiated delta 9-THC-induced hypothermia as did the alpha-adrenoceptor antagonist phenoxybenzamine. However, depletion of serotonin with P-chlorophenylalanine reduced the hypothermic response to delta 9-THC as did pretreatment with the serotonin antagonist methysergide. Inhibition of re-uptake of serotonin with clomipramine potentiated the hypothermia following delta 9-THC. It is suggested that the hypothermic effect of delta 9-THC in the mouse is mediated to a large extent via serotonergic mechanisms.

Animals↗
PubMed1979

Failed lumbar disc surgery and repeat surgery following industrial injuries.

One hundred and seventy-nine of the compensation patients in this study who had one low-back operation had to have repeat back surgery. One hundred and three Workmen's Compensation Board patients who were reoperated on by a number of surgeons in the Toronto area were independently reviewed with one to two years of follow-up. Many had residual back pain, limited lumbar movement, presisting nerve-root deficits, and psychological disturbances. Forty per cent of the second operations were successful. Subsequent operations yielded progressively poorer results and made more patients worse than better. Operations were frequently undertaken without clear indications or evidence of correctable organic lesions. The results of repeat operations were better when the preceding operation had given more than six months' relief, when sciatica overshadowed back pain, and when a definite recurrent disc herniation was found. Scarring and neurolysis, previous infection, repair of a pseudarthrosis, and adverse psychological factors precluded a good result. Careful patient selection based on total evaluation of the disability including psychological assessment, accurate localization of the lesion by detailed investigation, and, most important, a logical sequence of decisions based on clear, objective criteria are prerequisites for this complex and demanding surgery. Caution and restraint are required when contemplating repeat back surgery.

Accidents, Occupational↗