Biomedical subjects
Publications and source records attributed to N W Henry.
There are many benefits to participating in the activities of a low-level radioactive waste generators group. Among them are the sharing of ideas, experience, and successes; ready access to information on all aspects of radioactive waste disposal; and the ability to have input into the regulatory and decision making processes.
Two similar groups of 14 calves were housed and fed identically in individual pens on a calf-rearing farm. The groups were balanced for weight and immunological status as determined by zinc sulphate turbidity values. When an outbreak of enteric and respiratory disease occurred one group was treated with 20 mg chlortetracycline hydrochloride/kg bodyweight daily for seven consecutive days, by adding the active ingredient to the milk replacer, while the other group was left untreated. Both groups received additional therapy as required. The calves were examined daily during the period of treatment and the clinical observations were assessed and analysed statistically. There was a significant difference between the clinical scores of the two groups on the second day of treatment (P less than 0.05) and on all subsequent days (P less than 0.01) indicating that the calves receiving chlortetracycline hydrochloride were less affected by the disease outbreak. The abnormal enteric and respiratory signs were associated with several potential pathogens including bacteria, viruses and protozoa. The treatment was therefore effective against enteric and respiratory disease involving several organisms.
Rats were exposed to TiO2 by the inhalation route at concentrations of 0, 10, 50, or 250 mg/m3 for 6 hr/day, 5 days/week for 2 years. Lung weights of rats at 10 mg/m3 were within normal limits after 2 years exposure. Lung weights increased significantly after 6 months at 50 mg/m3 and after 3 months at 250 mg/m3. After 2 years exposure, TiO2 retention in dried lung was 3.1% (26.5 mg per lung) at 10 mg/m3, 16.9% (124 mg per lung) at 50 mg/m3, and 28% (665 mg per lung) at 250 mg/m3. Lung clearance mechanisms appeared to be overloaded at 250 mg/m3. Dust particles were retained in the lung in a dose-related fashion, but there was no significant difference in lung clearance rate between 10 and 50 mg/m3. Lung response at 10 mg/m3 satisfied the biological criteria for a "nuisance dust," while adverse effects resulting from gradually accumulated particles (8.1%, 67.7 mg per lung) were found after 1 year of exposure to 50 mg/m3. An early pulmonary response indicating an overloaded lung clearance mechanism was manifested by massive accumulation of dust-laden macrophages (dust cells), foamy dust cells, free particles, or cellular debris derived from disintegrated foamy dust cells in the alveoli adjacent to the alveolar ducts. Alveolar proteinosis also appeared to be an important marker of an overloaded lung clearance mechanism and was observed at 50 and 250 mg/m3 after 1 year of exposure. Cholesterol granulomas were developed with degenerative foamy dust cells at 50 and 250 mg/m3 after 1 year of exposure. After 2 years exposure at 250 mg/m3, bronchioalveolar adenomas occurred in the alveoli showing type II pneumocyte hyperplasia, while cystic keratinizing squamous carcinomas were developed from squamous metaplasia of alveoli showing bronchiolarization in the alveolar duct region. Since the lung tumors were a unique type of experimentally induced tumors under exaggerated exposure conditions and have not usually been seen in man or animals, their relevance to man is questionable.
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Experimental breakthrough times obtained from evaluating respiratory canisters to acrylonitrile vapors at various concentrations are presented and compared to estimated breakthrough times calculated from Nelson's equation for organic vapors adsorbed on activated carbon. The slope of the regression for breakthrough time vs. concentration of acrylonitrile was found to compare closely to that derived from Nelson's equation in the concentration range from 30 to 1000 ppm. This demonstrates that the equation is capable of predicting breakthrough times for organic compounds which, like acrylonitrile, have low molecular weights and boiling points. This ability to predict service life is also influenced by other important factors such as relative humidity and amount of activated carbon packed in a canister. Results of this evaluation illustrate the need to determine breakthrough times for compounds under controlled conditions similar to those encountered in the field, especially at low concentrations. Industrial hygienists should use experimentally derived breakthrough times to predict the service life of an air purifying device if they are available.
Rats and dogs were exposed to heated phenyl glycidyl ether (310 degrees C) vapor at average levels of 1.3, 5.0, and 11.8 ppm (v/v) for 6 hr/day, 5 days/wk, for 90 days. No adverse effects were observed in the dogs and rats other than alopecia in rats at the dose levels of 5.0 and 11.8 ppm. Microscopically, the skin lesions revealed slight acanthosis, hyperkeratosis, and occasional patchy parakeratosis in the epidermis. Follicular keratin plugs were observed with hyperkeratosis of epithelium in the hair follicles and sebaceous glands. Inflammatory reaction was mainly confined to the perifollicular region and affected the hair follicles, resulting in atrophy. The number of hair follicles in the resting stage appeared to increase. The hair shafts revealed impairment of keratinization and fragmentation. Extracted hairs showed an increase in the number of dystrophic follicles and constricted or broken hair shafts.
The inverse relationship between blood lead concentration and aminolevulinic acid dehydrase (ALAD) is well known. Recently, it has been suggested that a similar relationship exists between carboxyhemoglobin (COHb) and ALAD activity. This study was undertaken to examine more closely the possible effect of carbon monoxide on ALAD. Blood from 19 human volunteers was analyzed for both carboxyhemoglobin and ALAD activity. Smokers had significantly lower concentrations of ALAD than nonsmokers and a rise in carboxyhemoglobin concentration was assocaited with a fall in ALAD activity. The in vitro bubbling of carbon monoxide into human blood did not significantly effect ALAD activity. Four groups of rats (10 per group) wre exposed to carbon monoxide or dietary lead acetate according to the following design: (I) Control--no Pb or CO; (II) 500 ppm Pb acetate in diet; (III) 250 ppm CO four hours/day X 5 days/week X 4 weeks; (IV) Both Pb and CO. Analysis of the rat data showed a significant depression of ALAD by lead. The activity of ALAD in the rats exposed to CO was significantly increased suggesting the possibility of an adaptive phenomenon.
Whole blood, as withdrawn, from lead-exposed dogs was added in varying proportions, to whole blood, as withdrawn, from normal (non-exposed) dogs. The resultant red cell ALADP activities and lead concentrations of the mixtures were then determined. It was found that the resultant ALAD activities could be predicted on the basis of simple dilution of the blood with normal ALAD activity by the blood with severely reduced ALAD activity. The observed values for ALAD of the mixtures related to resultant lead concentration according to the equation: Y = a+ bx, rather than to the equation log y = a+ bx as reportedly observed for samples of blood from lead-exposed humans, and from lead-fed dogs. There was no evidence that the ALAD activity contributed by the portion of normal blood in the mixture was affected by the lead contributed by the blood from the lead exposed dog. This is considered as evidence that the reduction in red cell ALAD activity observed in lead-exposed dogs is not an in vitro artifact inherent in the method used to determined ALAD activity...
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Clinical-chemistry values were determined in young specific-pathogen-free single-comb White Leghorn chickens, both uninoculated and inoculated intra-abdominally at one day old with one of several avian adenovirus isolants. Clinical values for plasma proteins and enzymes indicative of liver function were determined at 3, 7, 10, 14, and 21 days postinoculation. Plasma glutamic oxalacetic transaminase and glutamic pyruvic transaminase activities were elevated in the virus-inoculated birds, along with decreased albumin levels suggesting liver necrosis, Subsequent histopathologic evaluations confirmed hepatic necrosis in the virus-inoculated groups, demonstrating the potential value of clinical-chemistry assay techniques for diagnosing subclinical disease associated with avian adenoviruses.
The comparative pathogenicity of six avian adenovirus isolants for chickens was determined. The most virulent isolant was DPI-1, causing focal to massive hepatic necrosis with hemorrhage, while Tipton (Conn), Tipton (Purdue), GAL-1, and DPI-2 isolants were considered less pathogenic and produced only mild focal hepatic necrosis. The Indiana-C isolant was the least pathogenic and failed to produce any significant hepatic lesions. Intranuclear inclusions were observed in hepatocytes of all but the Indiana-C inoculated chickens on the third day postinoculation (PI), disappearing by the seventh day PI.