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Biomedical subjects

D Baker

Publications and source records attributed to D Baker.

At least 361 records · Page 20Linked to original sources
PubMed1982

Mortality and early retirement.

This article examines and compares the survival rates of persons claiming retired-worker benefits at age 62 with those who did not. The study is based on a sample of Social Security insured workers who reached age 62 during the period 1962-72. The proportion of men dying in the initial years after age 62 was higher among those who claimed benefits at age 62 than among those who did not. The same pattern held for women but the difference was very small. To the extent that survival after age 62 can be taken as an indication of health status at age 62, these data suggest that the age-62 claimants were somewhat more likely than others to have had health problems. The difference in survival rates between the two groups, however, was not as great as the difference in the incidence of health problems reported in surveys. Past surveys have shown that men receiving early retirement benefits were twice as likely as other men to report health problems. According to this study, survival rates for men claiming benefits at age 62 were only 3-5 percentage points lower by age 68 than those for other insured men. Within any given age cohort, the difference between survival rates of age-62 claimants and other insured men widened over time. Survival rates improved across the age cohorts. Among the men, survival rates improved somewhat more for the age-62 claimants than for others.

Age Factors↗
PubMed1982

Hepatotoxicity of bile acids in rabbits: ursodeoxycholic acid is less toxic than chenodeoxycholic acid.

The hepatotoxic effects of cholelitholytic bile acids, ursodeoxycholic and chenodeoxycholic acids, were compared with each other and with those of lithocholic acid, a known hepatotoxic bile acid, in the rabbit. Male New Zealand white rabbits were fed regular laboratory chow containing ursodeoxycholic, chenodeoxycholic, or lithocholic acid at a concentration of 0.5 per cent (w/w) for 14 days. The control group was fed the chow without added bile acids. The mortality rate was highest (six of 12) in the lithocholate group, intermediate (two of eight) in the chenodeoxycholate group, and lowest (none of six) in the ursodeoxycholate group. Light microscopy of the liver revealed fibrosis, inflammation, and bile duct proliferation in the portal regions in the three experimental groups; however, the lesions in the lithocholate and chenodeoxycholate groups were more severe and often associated with periportal extension of fibrosis and focal necrosis of the parenchyma. In addition, electron microscopy revealed distortion of bile canaliculi, conspicuous bundles of intermediate-sized filaments, expansion of pericanalicular cytoplasmic matrix due to apparent accumulation of microfilaments, prominence of lysosomes, and fragmentation of cisternae of the rough endoplasmic reticulum. These ultrastructural changes were less marked and often absent in the ursodeoxycholate group. The serum L-alanine aminotransferase activity increased 5- to 6-fold in the lithocholate and chenodeoxycholate groups, whereas it remained less than 2-fold of the control level in the ursodeoxycholate group on day 14. The serum lithocholate concentration was markedly elevated to comparable levels in all three groups, whereas ursodeoxycholate was highly increased in the ursodeoxycholate group but undetectable in the other groups at the time of sacrifice. It is concluded that (1) although the oral administration of three bile acids induces hepatic injuries in the rabbit, ursodeoxycholate causes less severe injury than do the other two, (2) the advantage of ursodeoxycholate versus chenodeoxycholate is probably relative rather than absolute, (3) lithocholate formed through metabolic conversion from ursodeoxycholate may be responsible for the most part for hepatotoxicity, and (4) it is possible that the concurrent presence of ursodeoxycholate may mitigate lithocholate's hepatotoxicity.

Animals↗
PubMed1981

Dose local x-irradiation of a tumor increase the incidence of metastases?

KHT sarcomas were implanted into the right rear legs of C3H mice. Animals receiving no treatment died at 32 days with a 67% incidence of metastatic tumors. A dose of 6000 rads in ten fractions over 12 days, starting ten days after implant, delivered to the primary tumor (with the remainder of the body shielded) produced 55% local tumor control. However, 83% of the mice with local tumor control, subsequently developed metastatic lesions. Amputation of the tumor-bearing leg either prior to the start of radiation treatment, at the end of treatment or at intervals during treatment or sham treatment, indicated that 1) metastases occurred predominantly during the initial three radiation fractions and 2) the increased incidence of metastases following irradiation was a result of the manipulations associated with the irradiation and not the irradiation per se. Irradiation did not change the distribution of organ sites involved with metastatic tumors compared to untreated or sham-treated tumors.

Animals↗
PubMed1981

The influence of ICRF-159 and levamisole on the incidence of metastases following local irradiation of a solid tumor.

Courses of irradiation consisting of 6000 rad in ten equal fractions over 12 days delivered to KHT sarcomas in mice controlled 55% of the local tumors but 83% of the mice died from metastases. Three strategies to reduce the risk of metastatic spread were tested. The fractionation scheme was changed to deliver the same total dose using a large initial fraction followed by seven equal portions with the same overall time. ICRF-159 was used with the intention of partially synchronizing the tumor growth fraction in a radiosensitive state of the growth cycle and of promoting normalization of the tumor vasculature. Levamisole was used to stimulate the immune system. The combination of ICRF-159 with the eight-fraction radiation course proved to be effective for both increasing local control and decreasing the incidence of metastases. The addition of levamisole did not improve the results obtained with a combination of ICRF-159 and irradiation.

Animals↗
PubMed1981

Job decision latitude, job demands, and cardiovascular disease: a prospective study of Swedish men.

The association between specific job characteristics and subsequent cardiovascular disease was tested using a large random sample of the male working Swedish population. The prospective development of coronary heart disease (CHD) symptoms and signs was analyzed using a multivariate logistic regression technique. Additionally, a case-controlled study was used to analyze all cardiovascular-cerebrovascular (CHD-CVD) deaths during a six-year follow-up. The indicator of CHD symptoms and signs was validated in a six-year prospective study of CHD deaths (standardized mortality ratio 5.0; p less than or equal to .001). A hectic and psychologically demanding job increases the risk of developing CHD symptoms and signs (standardized odds ratio 1.29, p less than 0.25) and premature CHD-CVD death (relative risk 4.0, p less than .01). Low decision latitude-expressed as low intellectual discretion and low personal schedule freedom-is also associated with increased risk of cardiovascular disease. Low intellectual discretion predicts the development of CHD symptoms and signs (SOR 1.44, p less than .01), while low personal schedule freedom among the majority of workers with the minimum statutory education increases the risk of CHD-CVD death (RR 6.6, p less than .0002). The associations exist after controlling for age, education, smoking, and overweight.

Cardiovascular Diseases↗
PubMed1980

Characterization of an effective actinorhizal microsymbiont, Frankia sp. AvcI1 (Actinomycetales).

The actinomycete, Frankia sp. AvcI1, isolated from root nodules of Alnus viridis ssp. crispa was grown in axenic culture and used to inoculate host seedlings. This bacterium has been shown to be an infective and effective nitrogen-fixing microsymbiont which can be distinguished from other frankiae, in vitro, on the basis of size, distinctive morphology, and growth characteristics. Cross-inoculation studies indicated that the host range of this symbiont encompasses all of the members of the genera Alnus, Myrica, and Comptonia tested. In all cases, the symbioses developed were effective in fixing atmospheric dinitrogen.

Actinomycetales↗
PubMed1980

Characterization of an ineffective actinorhizal microsymbiont, Frankia sp. EuI1 (Actinomycetales).

The actinomycete, Frankia sp. EuI1, isolated from root nodules of Elaeagnus umbellata is an infective endophyte but which lacks the ability to form an effective nitrogen-fixing symbiosis with its host. This ineffective organism can be distinguished easily from other frankiae, in vitro, on the basis of size, morphology, and the elaboration of a diffusible pigment. Cross-inoculation studies indicated that the host range of this symbiont is narrow and probably restricted to the Elaeagnaceae. In all cases of nodulation the symbiosis never developed nitrogenase activity and the microsymbiont never produced endophytic vesicles within the infected host cells. Sporangia were produced in vivo and in vitro so the morphogenetic block is apparently restricted to vesicle formation.

Actinomycetales↗
PubMed1980

The use and health consequences of shift work.

The amount of shift work has increased dramatically in all industrialized nations during the past 30 years. In the United States, more than one-quarter of workers do shift work. The proportion of shift workers is highest in service and large-scale, capital-intensive industries. Shift work has spread subsequent to the rise of industrialization and the development of large corporations. It is used primarily to maximize the profits of the owners of these industries. On the other hand, it has substantial social and economic costs in terms of the ill health of shift workers. They suffer significantly more sleeping disturbances, nervous troubles, and disturbances of the alimentary tract. They also report disruptions in their family and social lives. The adverse consequences of shift work could be decreased by designing physiologically and socially appropriate shift schedules and by providing necessary additional services for shift workers. Unfortunately, these changes will be inadequate unless they are accompanied by efforts on the national level to restrict the use of shift work. Workers must push for laws restricting shift work to industries where it is technically necessary. Since shift work is really only one manifestation of the increasingly complex social and technical organization of work forced on workers in the drive to maximize profits, they must ultimately act together to gain control over their working conditions.

Attitude↗
PubMed1979

Differentiating minimal brain dysfunction and temperament.

After referral to a pediatric neurologist for problems in behavior and learning, 61 children aged from three to seven years were assigned to one of four diagnostic groups: (1) minimal brain dysfunction (MBD); (2) hyperactivity; (3) learning disability; and (4) other criteria. Their temperament profiles were determined by the Behavioral Style Questionnaire. The disproportionately large number of children with more difficult temperament diagnoses in the referred population indicates that teachers and physicians may have mininterpreted a less adaptive behavioral style as evidence of neurological dysfunction. Those diagnosed clinically as having MBD were less adaptable, less persistent, more active and more negative than the control population. This suggests that MBD overlaps with difficult temperament. Children in the other three groups were temperamentally similar to the MBD group, which raises doubt about the advisability of diagnosing MBD on the basis of behavior alone. A comprehensive neurobehavioral profile is necessary to separate clearly the various factors contributing to problems in school performance.

Affective Symptoms↗
PubMed1978

A new device to support handicapped patients during venography or myelography.

The authors describe a seating device which holds the patient in position when the x-ray table is tilted and permits non-weight-bearing venograms to be obtained in handicapped as well as normal patients. Simultaneous bilateral venography reduces the study time considerably. The device is also helpful in lumbar myelography in paraplegics.

Persons with Disabilities↗
PubMed1977

Doppler echocardiography. Use of a graphical display system.

Pulsed Doppler echocardiography (PDE) is a technique for evaluating blood flow characteristics at specific locations within the heart and great vessels. Because this method assesses blood flow rather than cardiac structures, PDE complements the findings of M-mode echocardiography. A new on-line graphical method for displaying pulsed Doppler information provides 1) a printed, permanent record of flow information, 2) precise timing of blood flow events, and 3) information on the direction of flow in the heart and great vessels.

Aortic Valve↗