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Biomedical subjects

C J Johnson

Publications and source records attributed to C J Johnson.

At least 91 records · Page 5Linked to original sources
PubMed1983

A viral subunit immunogen for porcine transmissible gastroenteritis.

An immunogenic component was isolated from both the Illinois (propagated in young swine) and the Miller (cell culture-adapted) strains of porcine transmissible gastroenteritis (TGE) virus. The viral subunit was released from the virion by sonication and was separated from intact virus and other viral components by isopycnic centrifugation. It had a buoyant density in sucrose of 1.02 g/ml. Further purification consisted of gel filtration through Sephadex G200, in which process the immunogen, with a molecular weight of approximately 25 000, was the last component to be eluted. A group of ten young, weaned swine, inoculated intramuscularly with two or three 1-mg doses of the viral subunit were protected against challenge with virulent TGE virus, probably by the induction of secretory IgA. The immunogen also induced a humoral immune response of variable magnitude (titers ranging from 8 to 5 625) in the animals. These antibodies are not believed to be directly related to protection against infection. They can, however, be easily identified by serologic procedures and may serve as a convenient indicator of responsiveness to the TGE viral immunogen.

Animals↗
PubMed1983

Lactogenic immunity to transmissible gastroenteritis virus induced by a subunit immunogen.

A subunit prepared from transmissible gastroenteritis (TGE) virus and used to immunize 24 gilts prior to farrowing induced production of specific antibody in the serum and milk. Challenge of pigs, two to seven days of age and suckling on the vaccinated gilts, with the Illinois strain of TGE virus resulted in morbidity of 28% and mortality of 4% as compared with 100 and 73%, respectively, for control piglets. Piglets nursing on a sow which had been immunized approximately 10 months previously were not protected, indicating that lactogenic immunity may be of short duration. Revaccination of this animal resulted in an anamnestic response.

Animals↗
PubMed1982

Environmental and health effects of the nuclear industry and nuclear weapons: a current evaluation.

The nuclear weapons industry in the U.S. comprises nine major plants, supported by a network of subcontractors and grantee institutions. Weapons development progresses at the Lawrence Livermore and Los Alamos Laboratories under the auspices of the University of California. Fissionable materials and tritium are produced at the Savannah River Plant (du Pont) or at Hanford. Reprocessing of plutonium and weapons grade uranium and manufacture of components are carried out at Rocky Flats (formerly Dow, now Rockwell Int.). Large amounts of radionuclides are generated or involved in operations at most of the nine plants. Internal reports of surveillance efforts by weapons plant personnel to monitor emissions of radioactive gases and particulates have now been released by several of the plants (in one case through litigation). Those reports document major releases of radioactive gases and particulates to the environment in the past, and continuing routine releases of some importance. Few investigations have been made of effects from these potent carcinogens in local populations. There have been several preliminary reports (Rocky Flats, Los Alamos and Savannah River) and one comprehensive report [Ambio 10: 176 (1981)]. Evidence of significantly increased rates of cancer of the more radiosensitive organs has been demonstrated. Adequate cancer registry and vital statistics data are essential for the comprehensive investigations of somatic and genetic effects which should be carried out around all nuclear installations near population centres.

Environmental Exposure↗
PubMed1981

Restaurant-associated type A botulism: transmission by potato salad.

In the period November 13-18, 1978, seven cases of type A botulism occurred in persons who had eaten in a restaurant in Colorado. The outbreak was recognized when two persons who had independently eaten at the restaurant were hospitalized with an illness compatible with botulism. Surveillance efforts identified five additional cases. Potato salad made at the restaurant and available for service during an 11-day period was epidemiologically incriminated as the vehicle of botulinal toxin transmission (p less than 0.00001). Laboratory studies showed that Clostridium botulinum spores on the surface of potatoes could survive baking in the manner used by the restaurant and that botulinal toxin could be produced in potatoes contaminated with C. botulinum spores.

Botulism↗
PubMed1979

Myocardial tissue concentrations of magnesium and potassium in men dying suddenly from ischemic heart disease.

Optimum tissue levels of magnesium and potassium ions are essential to the structure and function of the myocardium. We hypothesized that an inapparent deficiency of one or both of these elements might contribute to sudden cardiac death in a susceptible person, and in this study investigated levels of these elements in the myocardium of men experiencing sudden death to determine if there was such an association. Subjects dying suddenly with ischemic heart disease had significantly lower levels of myocardial tissue magnesium and potassium than the controls (men dying of acute trauma). The four lowest potassium values were obtained for the only men in the group with a history of angina (P less than 0.0005). Three of the men with angina also had the lowest tissue magnesium levels (P less than 0.005). The intriguing finding gives support to the hypothesis.

Angina Pectoris↗
PubMed1979

The effect of hypothyroidism on growth, serum growth hormone, the growth hormone-dependent somatomedin, insulin-like growth factor, and its carrier protein in rats.

To study the possible mechanisms involved in growth retardation associated with hypothyroidism, serum T4, GH, the GH-dependent somatomedin, insulin-like growth factor (IGF), and its carrier protein (CP) were measured in hypothyroid rats and their age-matched controls. Three groups of rats were studied: infant, immature, and adult. Marked hypothyroidism (serum T4, less than 1 microgram/dl) was produced in experimental animals by providing them with drinking water containing 0.05% propylthiouracil. Infant and immature hypothyroid rats weighed markedly less than normal controls and had significantly reduced serum levels of GH, IGF, and CP. Normal adult rats, treated with propylthiouracil for 60 days, also weighed considerably less than control animals and exhibited a significant drop in serum GH, IGF, and CP during this period. The administration of bovine GH to hypothyroid adult rats for 7 days did not restore either IGF or CP levels to normal, indicating that their decrease in serum was, in part, a direct result of hypothyroidism per se. These results indicate that serum levels of GH, IGF, and CP are at least partly under thyroid hormone control. Furthermore, these studies suggest that the growth retardation associated with hypothyroidism may be mediated through somatomedin activity.

Aging↗
PubMed1979

NSILA and foetal growth.

Employing a sensitive competitive protein binding assay for NSILA (non-suppressible insulin-like activity), circulating levels of this somatomedin (SM) have been measured throughout pregnancy, at parturition, and in foetal and newborn sera. Acid-dissociable serum NSILA (mean +/- SEM) in 57 women was significantly higher during pregnancy (1106 +/- 46 microunits/ml), than in 11 adult non-pregnant control subjects (844 +/- 22 microunits/ml), but not correlated with week of gestation or with serum growth hormone (GH) or cortisol levels. At parturition, the NSILA concentration in 28 cord sera (598 +/- 38 microunits/ml) was significantly less than in the corresponding maternal sera (1039 +/- 63 microunits/ml). The NSILA levels in 23 premature newborns (370 +/- 20 microunits/ml) and 8 small-for-gestational-age newborns (310 +/- 46 microunits/ml) were significantly less than in 33 term newborns (494 +/- 18 microunits/ml). Serum NSILA in 56 term and premature newborns exhibited a significant positive correlation both with gestational age and birth weight but not with serum GH or cortisol levels. These data suggest that the maternal-foetal growth-promoting system is a highly complex one in which NSILA levels both in maternal and foetal circulations appear to be under multifactorial control.

Adolescent↗
PubMed1976

Plutonium hazard in respirable dust on the surface of soil.

Plutonium-239 in the fine particulate soil fraction of surface dust is subject to suspension by air currents and is a potential health hazard to humans who may inhale it. This respirable particulate fraction is defined as particles less than or equal to 5 micrometers. The respirable fraction of surface dust was separated by ultrasonic dispersion and a standard water-sedimentation procedure. Plutonium concentration in this fraction of off-site soils located downwind from the Rocky Flats Nuclear Weapons Plant (Jefferson County, Colorado) were as much as 380 times the background concentration. It is prposed that this method of evaluation defines more precisely the potential health hazard from the respirable fraction of plutonium-contaminated soils.

Colorado↗