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Biomedical subjects

R Harrison

Publications and source records attributed to R Harrison.

At least 289 records · Page 16Linked to original sources
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Postradiation dental extractions: a review of the literature and a report of 72 episodes.

This report outlines our experiences involving 72 episodes of postradiation dental extraction over an 11-year period. Bone exposures of 3 months or longer developed following 16 of the 72 postradiation extraction episodes (22%). The necrosis rate in the mandible was 29% (13 of 45) and in the maxilla was 11% (3 of 27). The risk of bone necrosis increased when the dose to bone exceeded 6,500 rad, and when 75% or more of the body of the mandible was within the radiation treatment volume. Five of the 13 mandibular bone necroses precipitated by postradiation extractions eventually required radical resection of the affected portion of the mandible. The remaining eight mandibular episodes healed with conservative measures. When possible, given the two above conditions, root canal therapy rather than dental extraction should be employed to resolve mandibular dental infection within the radiation field after radiotherapy.

Dose-Response Relationship, Radiation↗
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Osteoradionecrosis: predisposing factors and outcomes of therapy.

Eighty-three episodes of osteoradionecrosis are reported. Of those episodes affecting the mandible (78), 23 (29.5%) required radical resection. The most common precipitating factors were postradiation extractions (22/83), periodontal disease (19/83), and preradiation extractions (17/83). Those episodes initially located within the zone of attached mucosa fared well with conservative measures while those initially located beyond the zone of attached mucosa fared poorly. In bone necroses where the external radiation dose to the affected bone exceeded 7,000 rad, the mandibular resection rate was high (44%). The most effective way of resolving advanced bone necroses was achieved with a course of hyperbaric oxygen therapy combined with a surgical sequestrectomy.

Combined Modality Therapy↗
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Physician autonomy in the Federal Republic of Germany, Great Britain and the United States.

The concepts of 'professionalism' (including autonomy) and 'management' (involving the control of others) are logically opposed; but, in the field of health care, physicians and managers have largely co-existed without such opposition. International pressures for cost containment, however, now raise questions about the future nature of physician autonomy. This paper attempts, firstly, to conceptualize the nature of clinical autonomy as a number of independent components; secondly, to describe the nature of such autonomy in three countries in terms of these components; and, thirdly, to identify related questions for future research.

Authoritarianism↗
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Detection of pion-induced radioactivity by autoradiography and positron emission tomography.

An autoradiographic technique incorporating a new imaging system was used to detect pion-induced radioactivity in Plexiglass and the results were compared with aluminium activation and PET imaging. The activity distribution in the region of the pion-stopping peak was similar in all three cases. Another large signal in the entrance region due to in-flight interactions [12C(pi-, pi- n) 11C] was detected by autoradiography and by PET but was not reflected in the aluminium activation measurements. This new technique is capable of defining the stopping region in phantoms with a better resolution than PET scanning and is useful as a complementary technique to other methods of pion dosimetry.

Autoradiography↗
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Pesticide-related illness among migrant farm workers in the United States.

Surveillance data show that pesticide-related illness is an important cause of acute morbidity among migrant farm workers in California. A few categories (organophosphates and carbamates, inorganic compounds, and pyrethroids) account for over half of the cases of acute illness. Skin effects dominate the illnesses, although ocular and systemic effects are also common. Exposures occur in various ways (e.g., residues, drift), suggesting that the use of pesticides creates a hazardous work environment for all farm workers. The health care system provided through the Migrant Health Program appears to be underutilized, partially due to barriers to health care access. Pesticide hazards should be ranked based on acute toxicity, chronic toxicity (including reproductive risks), carcinogenic potency, volume applied, and magnitude of worker poisonings. Current surveillance effort should be supported. Risk prevention should focus on substitution of safer compounds, establishing effective protections, and ensuring that these measures are enforced. Improved education for health care providers should be a priority. Growers should be educated about alternative forms of pest control and incentives should be provided to encourage their use.

Agricultural Workers' Diseases↗
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Feulgen-DNA content of human sperm and outcome of in vitro fertilization.

Feulgen-DNA content of sperm was quantified in fresh semen samples of 20 consecutive couples during preparation for in vitro fertilization to measure the condensation state of sperm chromatin. Results were expressed as a percentage of expected haploid DNA value (1c). No significant differences were found between those who did not get pregnant, those who went full term, and those who aborted. Because fertilization can occur with a minority of normal sperm, it is concluded that the present findings do not provide useful clinical information about pregnancy outcome and in vitro fertilization.

Coloring Agents↗
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Spermatozoal DNA flow cytometry and recurrent miscarriage.

Clinical investigations of the male partner of couples with recurrent miscarriage involves investigation of abnormalities in paternal chromosomes. This route of investigation does not include analysis of semen parameters. This investigation was conducted to evaluate DNA flow cytometry profiles of spermatozoa following staining with propidium iodide of couples attending the Pregnancy Loss Clinic for recurrent miscarriage. Ejaculates of 21 men were included in this study. DNA fluorescence was measured on the Becton Dickinson Fac Star Plus. Data were correlated with spermiogram parameters. The neat semen median minus peak channel values were negatively correlated with motility (p < .05). Therefore, DNA flow cytometry can provide confirmatory evidence for conventional semen analysis and is useful as a preliminary screening procedure for clinical management of the couple. It could also be used in association with programs for the assessment of possible reproductive toxicity and infertility in couples with recurrent miscarriage.

Abortion, Habitual↗
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Pilot survey of urinary porphyrins from persons transiently exposed to a PCB transformer fire.

In rats and humans chronically exposed to large amounts of PCB (polychlorinated biphenyls) and PCDF (polychlorinated dibenzofurans), the urinary excretion of uroporphyrin and coproporphyrin are altered. However, porphyrin excretion in humans after acute transient low level exposure has not been evaluated. Following such an exposure in which bystanders and firefighters were in contact with smoke from a PCB transformer fire, we surveyed 90 self-referred individuals by questionnaire and by determining single 24 hour urinary excretion of uroporphyrin and coproporphyrin 2-4 weeks after the fire. Questionnaire variables that assessed exposure were not associated with the magnitude of either uroporphyrin or coproporphyrin excretion. Uroporphyrin excretion was slightly elevated in nine subjects (range 66-106 micrograms/24 hours, normal less than 60), which is much less than in clinical cases of porphyria cutanea tarda. Uroporphyrin excretion was inversely correlated with coproporphyrin excretion (r = -0.3844, p = 0.0002). For 5 subjects (3 with elevated initial uroporphyrin excretion) retested at 3-4 weeks after the fire, all 5 showed increases in uroporphyrin and decreases in coproporphyrin excretion when compared to initial determinations. These two reciprocal relationships would be the expected result from inhibition of uroporphyrinogen decarboxylase, a known experimental effect of PCB and PCDF in mice. Overall, urinary porphyrin excretions were not altered or sensitive measures of exposure.

Air Pollutants↗
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An assessment of mood in males attending an infertility clinic.

This study was undertaken to assess the mood profile in men seeking treatment for infertility and also to investigate if aetiological factors of infertility have any impact on mood. This was a prospective questionnaire study and the setting was the Human Assisted Reproduction Ireland (H.A.R.I.) unit in the Rotunda Hospital. Fifty men participated in the study and were required to complete the Hospital Anxiety and Depression Scale (HADS) questionnaire. The results were analysed using an ordered logit regression analysis on the statistical software package DATA DESK 5.0.1. There were no cases of depression in the study population. However, detectable anxiety levels were displayed in 31.9% of men. Those with severe oligospermia had a higher mean anxiety score (8.5) compared with other patient subgroups. Clinically significant anxiety was found in 8.5%; all of these men had a male-factor problem. The study population was relatively small but some interesting trends were observed. A larger trial is warranted to assess if genuine at-risk groups exist.

Anxiety↗
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Medical surveillance for workplace hepatotoxins.

In contrast to clinical practice, the objective of medical surveillance in a workplace population with potential exposure to hepatotoxins is to detect people with occupation-associated liver dysfunction who either have or are at risk for developing clinical disease. Ideally, medical surveillance tests for hepatotoxicity should have, either alone or in combination, a high positive predictive value.

Chemical and Drug Induced Liver Injury↗
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Nongonococcal urethritis incidence has fallen at one university health service: are "safer sex" messages being heard?

The authors determined the incidence of nongonococcal urethritis (NGU) longitudinally in patients attending a university health service between August 1986, and May 1988. During this period, the authors observed a statistically significant fall in NGU incidence. This fall coincided with awareness of AIDS risks due to national and local media encouragement of condom use and avoidance of anonymous or promiscuous contacts. Although the authors have no evidence that these educational efforts resulted in the observed fall in NGU incidence, other examined, potentially intervening variables can not completely explain the observed changes. A fall in NGU incidence may be a marker for a more generally decreased risk of sexually transmitted diseases (STDs) in at least some men.

Acquired Immunodeficiency Syndrome↗