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Biomedical subjects

K J Donham

Publications and source records attributed to K J Donham.

At least 55 records · Page 3Linked to original sources
PubMed1984

Acute effects of the work environment on pulmonary functions of swine confinement workers.

A sample population of owner/operators of swine confinement production facilities (21 subjects in 21 different facilities) were tested by spirometry immediately before and after a 4-hr work period. These confinement workers had statistically significant decrements in flow rates ranging from 3.3% (mean FVC) to 11.9% (mean FEF25-75). The air within the work environment was sampled for particulates and gases during the exposure period. There was suggestive evidence for a dose-response association between environmental exposures to carbon dioxide (CO2) and hydrogen sulfide (H2S). There was also some evidence for an additive relationship between smoking and work environment exposure on decline in lung function. The results of this study indicate that those working in swine confinement buildings experience irritation to the respiratory tract which is manifest by decreased flow rates. These findings suggest this exposure represents an emerging occupational health hazard. Further studies are warranted to assess the potential for chronic or irreversible damage to the respiratory tract.

Agricultural Workers' Diseases↗
PubMed1984

Inactivation of bovine leukemia virus-infected lymphocytes in milk.

The survival of bovine leukemia virus (BLV)-infected lymphocytes in milk was studied to determine whether treatments similar to those on a dairy farm would inactivate BLV. Bovine leukemia virus was found in milk stored for 72 hours at 1.1 C (34 F); milk constituents, such as protein, total solids, minerals, fat, and somatic cell concentration did not affect the presence of BLV. Infectivity also was found in the cream layer of milk. Pasteurization at 63 C for 30 minutes did inactivate BLV-infected lymphocytes.

Animals↗
PubMed1984

The combined effects of asbestos ingestion and localized X-irradiation of the colon in rats.

We hypothesized that the normal bowel may afford some protection to tissue penetration of ingested asbestos, due to the mucus produced by goblet cells which normally coats the gut surface. To study this, we exposed localized segments of the colons of laboratory rats to X-irradiation. These animals were then divided into 3 groups which were fed either a diet containing 10% chrysotile asbestos, a diet containing 10% non-nutritive cellulose fiber, or a standard laboratory diet. Autopsies and histopathology were performed on all animals that died spontaneously and those that were killed at 350 days. Various types of inflammatory and degenerative lesions were commonly seen, but there was little difference in frequency between the diet groups. Five adenocarcinomas and two sarcomas were seen in the fiber groups (three tumors in the asbestos group and four tumors in the cellulose group) but no tumors were seen in animals on the standard diet. There was not a significant difference in tumor rates between the asbestos and cellulose groups, nor was there a significant difference between the combined fiber groups and the standard diet group. It was concluded that the x-ray treatment resulted in localized damage to the colonic mucosa and, therefore, theoretically disrupted the normal mucus coating allowing the potential for increased tissue penetration by the asbestos. Ingested asbestos did not increase the risk for tumor development and, therefore, does not seem to be co-carcinogenic or a tumor promoter in combination with disruption of mucus coating and localized X-irradiation.

Animals↗
PubMed1984

Animal studies of potential chronic lung disease of workers in swine confinement buildings.

The pathologic changes in laboratory animals housed in a swine confinement building were studied to predict potential chronic health effects on persons working in these buildings. Rabbits and guinea pigs were maintained for 12 months either in a confined nursery-grower unit (test animals) or in conventional laboratory animal housing (controls). Necropsies and histopathologic examinations were performed on animals that died prematurely or were killed at termination of the study. Blood serum from the animals was examined for antibodies to extracts from swine confinement house dust. The confinement atmosphere was monitored for environmental pollutants. Concentrations of gases and dust in the air of the confinement building were comparable to those found in a typical swine confinement building. Pulmonic lesions seen in the test rabbits and guinea pigs included diffuse interstitial histiocytic pneumonia. Tracheal and nasal turbinate lesions included epithelial hyperplasia and metaplasia, with submucosal infiltration of plasma cells and heterophils. Blood from the test animals contained serum precipitins to dust extract from confinement houses. The presence of precipitins combined with the microscopic appearance of the lungs indicated that an immunologic process, such as hypersensitivity pneumonitis, may be used to explain the basis of the observed lung lesions. The tracheal and turbinate lesions are best explained as a reaction to a chronic low-grade irritation.

Agricultural Workers' Diseases↗
PubMed1982

Carboxyhemoglobin values in swine relative to carbon monoxide exposure: guidelines for monitoring animal and human health hazards in swine-confinement buildings.

Miniature pigs were exposed, in an environmental chamber, to 55 mg of CO/m3 of air, 110 mg/m3, 220 mg/m3, or 330 mg/m3. Blood samples were taken from the swine every hour over an exposure period of 6 or 8 hours. After the pigs were removed from the chamber, blood samples were taken every 30 minutes for an additional 3 hours. The blood samples were measured by spectrophotometry for the amount of carboxyhemoglobin (COHb). On exposure to CO, the COHb values in the pigs increased in a linear fashion during the first 2 hours, then began to level off, reaching a peak concentration at 6 to 8 hours. The percentage of COHb in the blood after 6 hours' exposure to the different amounts of CO were as follows: 55 mg/m3 - 5%, 110 mg/m3 - 10.5%, 220 mg/m3 - 20%, and 330 mg/m3 - 27.2%. There was a linear relationship between the amount of CO exposure and the peak blood value of COHb. The present data provide guidelines for the use of COHb measurement in swine as a means to monitor the environment in swine-confinement buildings for potentially dangerous amounts of CO for swine and persons and to aid in the diagnosis of CO-induced perinatal disease in swine.

Animals↗
PubMed1982

Acute toxic exposure to gases from liquid manure.

Liquid manure storage is a common component of confinement systems for swine, beef, dairy, and veal operations. A mail questionnaire to a sample of swine producers indicated that more than 85,000 people in Iowa and an estimated 500,000 in the United States work in livestock confinement systems that use liquid manure storage. Deaths and illnesses in people with acute exposure to toxic gases emanating from the liquid manure have been recently reported. This communication reports results of the investigation of six such incidents. Hydrogen sulfide appears to be the main toxic substance involved, and agitation of the liquid manure is important in creating an acutely severely toxic environment. Preventive measures must include worker education and limitation of human exposure through control of environmental and human factors.

Adolescent↗
PubMed1982

Agricultural medicine: the missing component of the Rural Health Movement.

Agricultural medicine encompasses, the anticipation, recognition, diagnosis, treatment, prevention, and community health aspects of health problems peculiar to agricultural populations. Members of the agricultural population have been heretofore ignored in organized health efforts unless they happened to also be a member of a social, racial, or economic minority. However, members of the agricultural population encounter daily a variety of occupational and environmental health hazards, such as toxic chemicals and zoonotic infectious agents. The health status of the agricultural subgroup of the rural population is poorer than is commonly believed. For example, compared with other populations, members of this subgroup have excess rates of chronic illness, excess disability from respiratory conditions, and the highest death rate from occupationally related accidents. If a true improvement in the health of the agricultural population is to be realized, then its unique health problems must be recognized, and specific clinical, preventive, and community health aspects of its problems must be dealt with.

Adult↗
PubMed1980

The effects of long-term ingestion of asbestos on the colon of F344 rats.

Weanling F344 rats, which were fed a diet containing 10% chrysotile (B), were studied over their life-time to determine the effects of ingested asbestos on the colon. Control groups consisted of rats fed a diet containing a 10% nonnutritive cellulose or a standard laboratory rat diet. The pathological findings in the colons of 501 rats (189 on asbestos diet, 197 on fiber control diet, and 115 on standard control diet), are reported here. Epithelial tumors of the colon (eight adenocarcinomas and one adenoma) were found in nine of the rats on study. Four of the tumors were in asbestos-fed rats, two tumors were found in the non-nutritive cellulose controls, and three tumors were found in the standard laboratory rat diet controls. The probability (based on actuarial analysis) of developing adenoma or adenocarcinomas during the 32 months of the study were 7.4% for the asbestos-fed group, 3.5% for the fiber control diet and 4.0% on the standard control diet. In addition, one malignant mesothelioma of the type induced by intraperitoneally administered asbestos was found in the asbestos-fed group. Non-neoplastic lesions of the colon were also evaluated. The cumulative risk for development of any colon-associated lesion (non-neoplastic plus neoplastic lesions) was greatest for asbestos-fed rats (17.9%), compared to 13.6% for those fed the fiber control diet and 8.2% for those fed the standard control diet. The colon tissue levels of adenosine, 3'-5'-cyclic monophosphate (cAMP) were significantly lower in the animals fed asbestos compared to the control diets. Chrysotile fibers were seen by electronmicroscopy (e.m.) in six of ten ashed colon specimens of rats fed the asbestos diet. Although the differences in numbers of tumors between the animals fed asbestos and the controls were not statistically significant at the 5% level, we felt that the combination of observations including 1) evidence of increased probability of asbestos-fed animals to develop colon lesions in general; 2) evidence of a special type of mesothelioma in rats fed asbestos; 3) evidence for a cell regulator defect (lowered cAMP levels) in colon tissues of animals fed asbestos; and 4) evidence for asbestos fiber penetration of the colonic mucosa (e.m. studies) suggest that ingested asbestos is not inert in the colon.

Adenocarcinoma↗
PubMed1980

Epidemiologic relationships of the bovine population and human leukemia in Iowa.

Data from the Third National Cancer Survey and data collected under the auspices of the National Cancer Institute's Surveillance, Epidemiologic and End Results (SEER) Program were used to perform a descriptive epidemiologic study of leukemia in Iowa. Data were also collected on livestock population patterns in the state, and a survey was performed to locate cases of lymphosarcoma within the cattle population. Ecologic relationships between human leukemia, livestock populations and bovine lymphosarcoma were investigated. Iowa has higher rates than the national average for human leukemias. The lymphoid leukemias make up the majority of the excess leukemias. Excessive acute lymphoid leukemia (ALL) is seen in the ages under 20 years and over 60 years. The excess ALL is in males living in rural counties. There is no sex difference for chronic lymphoid leukemia (CLL), but there is a slight urban-rural differential. There is a high positive correlation between ALL in males and cattle density. This relationship is greater for daily cattle than for beef cattle. There is an additional positive relationship between counties with excessive ALL and the presence of dairy herds affected with bovine lymphosarcoma.

Adolescent↗
PubMed1980

Leprosy in a chimpanzee. Postmortem lesions.

A young (5-7 year old) male chimpanzee died 33 months after the first clinical manifestations of a naturally acquired disease that was similar to disseminated leprosy in man. At autopsy there were diffuse or multifocal histiocytic infiltrations of the skin, nasal mucosa, pharynx, lung interstitium, liver, spleen, sclera, testicles, adrenal glands, and peripheral lymph nodes. Major nerves of the forearms had extensive fibrosis. There were large numbers of acid-fast bacilli (AFB), many occurring as globi, in histiocytes in most affected tissues including nerves. The histopathologic features of the disease and the microbiologic and antigenic properties of the AFB in the tissues indicate that Mycobacterium leprae or an organism indistinguishable from it was the causative agent. This and other cases of leprosy in nonhuman primates indicate that studies of the development of nonhuman primate models for leprosy may be worthwhile.

Animals↗
PubMed1979

Regurgitation and choke in rats.

Male and female F344 rats choked on fecal pellets and regurgitant during the course of two long-term experiments. Each study involved feeding standard and high bulk diets containing 10% wood cellulose or 10% chrysotile asbestos fiber. Choke deaths occurred at all stages of the experiments. A total of 36 of 774 (4.6%) rats in the two studies died of choke. Females died of choke more frequently (26/382 or 6.8%) than did males (10/392 or 2.6%). Rats on high bulk diets were affected more frequently (33/571 or 5.8%), especially those on 10% asbestos diet (26/311 or 8.4%, than rats consuming standard diet (3/190 or 1.6%). The reason for the difference between females and males was not determined. Although choke may be related to some characteristics of high nonnutritive bulk feed fed in pellet form, the higher risk for females even on standard diet (3/95 or 3.2%) than for males (0/95) indicated that more than one factor operated in the etiology of these events.

Airway Obstruction↗
PubMed1978

Leprosy in a chimpanzee. Morphology of the skin lesions and characterization of the organism.

Microscopic features of lepromatoid lesions in a chimpanzee inoculated with bovine leukemia virus consisted of diffuse dermal infiltrations of foamy histiocytes, except for a subepidermal "clear zone" devoid of infiltrating cells. Acid-fast organisms were in histiocytes, dermal nerves and a branch of the left radial nerve. The organisms were more intensely acid-fast with the Fite-Faraco than with the Ziehl-Neelsen stain. The organisms did not oxidize 3,4-dihydroxyphenylalanine (dopa) to indole but their acid-fast staining quality was removed by pretreatment with pyridine. Human leprosy patients, inoculated simultaneously with chimpanzee and human lepromin, reacted similarly to both lepromins. Organisms, when inoculated into mouse footpads, multipllied in 6 months to a quantity that was compatible with their identification as Mycobacterium leprae.

Animals↗
PubMed1977

Spontaneous leprosy-like disease in a chimpanzee.

The clinical and laboratory findings of a spontaneous disease, resembling human leprosy, in a chimpanzee are described. The disease was a chronic progressive dermatitis characterized by nodular thickenings of the dermis and involving the ears, eyebrows, nostrils, and lips. A maculopapular rash was also present. Numerous acid-fast organisms were found in nasal swabs and in dermal lesions, including nerves. Attempts to culture acid-fast organisms in artificial media have failed. At this time, the only features of the etiologic agent of this disease that are inconsistent with those of Mycobacterium leprae are failure of the organisms to oxidize 3, 4-dihydroxyphenylalanine and failure to pyridine to remove the acid-fast staining property of the bacilli.

Animals↗
PubMed1977

Seroepidemiologic studies on the possible relationships of human and bovine leukemia: Brief communication.

A seroepidemiologic study was conducted in an attempt to identify antibodies against the bovine leukemia virus (BLV) in people exposed to cattle with lymphosarcoma. Farm families, farm employees, and veterinarians in contact with cow herds having documented cases of lymphosarcoma were tested for precipitating antibodies to the BLV with the agar gel immunodiffusion test. The cattle also were tested serologically. Information was collected form the farm families regarding consumption of unpasteurized milk from their dairy herd. Twenty-one dairy herds with documented cases of lymphosarcoma were identified. A total of 846 cows from these herds wre bled, of which 33% were serologically positive. No positive sera were found in the 45 dairy farmers, family members, and farm employees associated with the herds with lymphosarcoma. Consumption of raw milk was reported by 77% of the farm group. In addition, 83 veterinarians, 30 leukemia patients, and 200 control human sera were tested and found negative for antibodies to the BLV.

Adolescent↗
PubMedDate not supplied

Respiratory symptoms and lung function among workers in swine confinement buildings: a cross-sectional epidemiological study.

To study possible chronic respiratory problems of people working in swine confinement buildings, a cross-sectional epidemiological study was initiated. A cohort of swine confinement workers was matched for age, sex, and smoking history with nonconfinement swine producers. Pulmonary function studies and a survey questionnaire for chronic respiratory disease symptoms (the American Thoracic Society, Epidemiologic Standardization Project Questionnaire) were performed on both groups. Compared to controls, the confinement workers experienced significantly higher prevalence of chronic bronchitis and wheezing, (odds ratio 7 and 4, respectively). There were, however, no significant differences in baseline pulmonary functions. Based on the high prevalence of chronic respiratory disease symptoms, this study emphasizes an emerging occupational concern in agriculture to the estimated 500,000 persons working in swine confinement operations and the estimated 500,000 additional persons who work in poultry, veal, beef, or dairy confinement operations. It is important to study a representative population of these workers prospectively to determine if a progressive loss in lung function is evident.

Adult↗