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Biomedical subjects

M Russell

Publications and source records attributed to M Russell.

At least 145 records · Page 8Linked to original sources
PubMed1987

Risk assessment in environmental policy-making.

Environmental policy-making has become more dependent on formal, quantitative risk assessment because of increasing attention to the prevention of human health damage from toxic chemicals. Risk assessment helps set priorities for regulation of the very large numbers of chemicals that are of potential concern and helps direct limited social and government resources against the most significant risks. Although the scientific basis for risk assessment is often uncertain and the public and its representatives have often been confused by its use in regulatory decisions, the U.S. Environmental Protection Agency currently uses a variety of risk assessment techniques to set priorities, tailor regulations, and make decisions at particular sites. The Environmental Protection Agency also attempts to make the practice of risk assessment more consistent throughout the agency and to improve public understanding of the meaning of risk assessment and risk management.

Environmental Exposure↗
PubMed1987

The pathology of Q fever hepatitis. A case diagnosed by liver biopsy.

A 52-year-old woman with fever and low grade hepatitis had Q fever, a diagnosis made by the characteristic granulomas, containing fibrin and vacuoles, on liver biopsy and confirmed by serology. Fibrin was demonstrated in the granulomas but Coxiella burnetii antigens were not. The literature on the histopathology of the liver in both acute Q fever and Q fever endocarditis shows that none of the 220 cases of Q fever endocarditis, with one possible exception, had the characteristic granulomas of acute Q fever. Rather they displayed a range from normality through nonspecific reactive hepatitis to occasional nonspecific granulomas. Thus, the characteristic granulomas of acute Q fever appear to be transient even if active infection persists. The definition of chronic Q fever should have a temporal characteristic rather than a serologic one.

Female↗
PubMed1987

In vitro and in vivo susceptibility of the Lyme disease spirochete, Borrelia burgdorferi, to four antimicrobial agents.

The antimicrobial susceptibility of Borrelia burgdorferi isolated from human spinal fluid was determined in vitro and in vivo. A broth dilution technique was used to determine the MBCs of four antimicrobial agents. The Lyme disease spirochete was most susceptible to ceftriaxone (MBC, 0.04 microgram/ml) and erythromycin (MBC, 0.05 microgram/ml), then tetracycline (MBC, 0.8 microgram/ml), and finally penicillin G (MBC, 6.4 micrograms/ml). Syrian hamsters were used to determine the 50% curative doses (CD50s) of the four antimicrobial agents. Ceftriaxone and tetracycline had the highest activities, with CD50s of 24.0 and 28.7 mg/kg [corrected], respectively. Both erythromycin and penicillin G possessed low activities. The CD50 of erythromycin was 235.3 mg/kg [corrected], and the CD50 of penicillin G was greater than 197.5 mg/kg [corrected].

Animals↗
PubMed1986

Passive immunization of hamsters against experimental infection with the Lyme disease spirochete.

Hamsters passively immunized with as little as 0.0125 ml of immune rabbit serum (indirect fluorescent-antibody titer, 1:8,192) were protected from challenge with 1,000 50% infective doses of Borrelia burgdorferi. Cross-protection studies with Minnesota and Connecticut isolates of B. burgdorferi indicated no major differences in their capacity to elicit mutually protective antibodies in rabbits.

Animals↗
PubMed1986

Active immunization of hamsters against experimental infection with Borrelia burgdorferi.

The immunogenicity of a single dose of a whole-cell vaccine of inactivated Borrelia burgdorferi HSF (human spinal fluid isolate) was evaluated. Syrian hamsters were vaccinated subcutaneously and challenged by the intraperitoneal injection of 1,000 50% infectious doses of B. burgdorferi HSF 30 or 90 days postvaccination. Animals were sacrificed 14 days after challenge, and the kidneys and spleens were examined for spirochetes by cultural procedures. At 30 days postvaccination, 86 to 100% protection against infection was achieved in hamsters receiving 50 and 100 micrograms (dry weight) of vaccine. Protection was decreased to 60% with 25 micrograms of vaccine and was absent with 10 micrograms of vaccine. Resistance to infection decreased to 25, 40, and 5% for the 100-, 50-, and 25-micrograms vaccine doses, respectively, at 90 days postvaccination.

Animals↗
PubMed1986

Career profile of the Canadian Standardbred. III. Influence of temporary absence from racing and season.

The objective of the study was to examine the career profile of the average racehorse in order to establish normal values for performance. Records of race performance for a population of 762 horses randomly selected from the 1972 registrations of the Canadian Standardbred Horse Society were summarized and the pattern of racing by year and month from 1974 to 1983 inclusive recorded. Results were analyzed to determine the influence of sex, gait, age, and year of first race (starting year). The transformation log (1 + X) was used to achieve normality where necessary. Of the 762 horses, 507 raced, 56 (11.0%) of which took one or more complete seasons (years) off. No age predisposition was detected, and no significant difference in mean career performance between the group taking a season off and the remaining horses were found, with the exception of career length, which was longer for those temporarily absent from racing (p less than 0.001). No influence upon career pattern for horses off early in their career was observed but those off late showed indications of a subsequent fall in number of races per year and in times for the mile. Mean career duration was 25.66 to 28.38 months (95% confidence limits for the mean, n = 507). Absence from racing of at least one months duration was taken by 437 horses, mean percentage of career off 42.36 +/- 0.94% (mean +/- SEM), mean duration of periods off 4.43 to 4.71 months. Career duration in months and percentage off were only weakly related (r = -0.16).(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1986

Comparative effects of different animal and vegetable fats fed before and during carcinogen administration on mammary tumorigenesis, sexual maturation, and endocrine function in rats.

The purpose of this investigation was to determine whether diets high in animal or vegetable fat affected mammary tumorigenesis when fed to rats only prior to and during the initiation phase of carcinogenesis. Weanling 21-day-old female Sprague-Dawley rats were divided into different dietary treatment groups and were allowed to feed and libitum on one of the following diets: 5% (normal fat) corn oil; 20% (high fat) corn oil; 20% palm oil; 20% beef tallow; or 20% lard. At 52 days of age, all rats were given p.o. 7.5 mg 7,12-dimethylbenz(a)anthracene (DMBA). One week following DMBA administration, all rats were switched to the 5% corn oil control diet and were maintained on this diet for the duration of the experiment. Rats fed a 20% lard diet during the treatment period showed a significant increase in mammary tumor incidence and number 19 weeks after DMBA administration, when compared to all other dietary treatment groups. Rats fed a 20% beef tallow diet during this same time period also demonstrated enhanced mammary tumor development, during the 10- to 19-week time period after DMBA. Mammary tumor development in rats fed 20% corn oil or palm oil diets during this treatment period was similar to that of normal fat controls. Estrogens are potent stimulators of mammary tumor growth and development in rats. Because mammary tumorigenesis was enhanced in rats fed high animal, but not vegetable fat diets, it was possible that estrogens present in animal fat might be responsible for this stimulation. Further studies demonstrated however, that increased mammary tumorigenesis in rats fed diets high in animal fat could not be explained on the basis of endocrine stimulation. Average day of vaginal opening for all groups fed 20% fat diets was similar and occurred earlier than in normal fat controls. In addition, 50- to 65-day-old rats in the different dietary treatment groups showed no differences in basal or surge levels of serum prolactin, luteinizing hormone, or estradiol. Rat diestrus uterine weight also showed no significant differences among dietary treatment groups. Thus diets containing high levels of animal fat caused little if any increased estrogenic activity in rats. In conclusion, high dietary intake of lard and beef tallow, but not vegetable fat, fed from weaning until only 1 week after DMBA administration, significantly enhances mammary tumorigenesis in rats. The mechanism(s) by which animal fat induces this stimulation is not clear, but it does not appear to result from endogenous or exogenous endocrine stimulation.

Animals↗
PubMed1985

Chelation therapy. Unproved modality in the treatment of Alzheimer-type dementia.

Despite a dramatic increase in the understanding of the neuropathologic and neurochemical alterations accompanying Alzheimer's disease, by far the largest cause of progressive and incapacitating cognitive dysfunction in the elderly, physicians have as yet no pharmacologic agent that can be prescribed safely either to arrest or reverse this decline. This lack of effective therapeutic agents is contributing to the use by an increasing number of health professionals, including physicians and concerned families, of unproved, costly, and potentially dangerous modalities, such as chelation therapy. The purpose of this paper is to describe some individuals with Alzheimer-type dementia who have undergone chelation therapy.

Aged↗
PubMed1985

Effects of maternal administration of diethylstilbestrol and estradiol on the newborn guinea pig.

The subcutaneous injection of diethylstilbestrol (2.5 micrograms/day) into pregnant guinea pigs from the 28th or 40th day to term resulted in an accelerated tempo of differentiation of the genital tract of the female offspring at birth, as well as intense estrogenic stimulation. Estradiol (50 micrograms per day) injected over the same period caused insignificant estrogenic stimulation in the newborn. The normal embryogenesis of the genital tract is described and a pattern of caudocranial differentiation identified. The normal genital tract is described as a basis for the analysis of results in the newborn. Comparative studies in other animals are discussed.

Animals↗
PubMed1984

Learned histamine release.

Most of the effort directed at understanding the problems of allergy has focused on the interacting components of the immune system. The possibility that histamine may be released as a learned response has now been tested. In a classical conditioning procedure in which an immunologic challenge was paired with the presentation of an odor, guinea pigs showed a plasma histamine increase when presented with the odor alone. This suggests that the immune response can be enhanced through activity of the central nervous system.

Animals↗
PubMed1984

Maternal zinc status: a determination of central nervous system malformation.

Maternal serum zinc concentrations were estimated during 244 normal pregnancies and 15 abnormal pregnancies. The serum zinc concentrations were lower in the anencephalic pregnancies than in the normal control subjects. The serum zinc levels in women whose pregnancies terminated in a spontaneous abortion were normal. There was no variation of serum zinc level with gestational age between 15 to 18 weeks in normal pregnancies.

Abortion, Spontaneous↗
PubMed1983

Tetracycline and amphotericin B vaginal cream for mixed vaginal infections.

A tetracycline and amphotericin B vaginal cream (Vagmycin; Squibb) was highly effective in mixed vaginal infections. More than 95% of patients had symptomatic relief while 85% showed bacterial and clinical response. There appeared to be little difference whether the cream was applied for 1 week or 2 weeks. A group of asymptomatic patients were evaluated to compare alterations in normal and pathological organisms as a result of treatment.

Amphotericin B↗