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Biomedical subjects

C M Lang

Publications and source records attributed to C M Lang.

At least 91 records · Page 5Linked to original sources
PubMed1981

Evaluation of a chemical scrubber for the removal of gaseous contaminants from recycled air.

A chemical scrubber was evaluated for its ability to remove two gases with differing water solubilities from recycled air. Operating parameters of the scrubber were also evaluated and included effect on air temperature and humidity. Ammonia, which has a high water solubility, was completely removed from the recycled air. Even when ammonia was continuously infused into the isolator at the rate of 1.0 liter/minute, the concentration in the recycled air never rose above 1 ppm despite concentrations of ammonia in the isolator of 4,000 ppm. Sulfur dioxide, which has a much lower water solubility, was not as rapidly removed. Continuous infusion of sulfur dioxide at the same flow rates used for ammonia resulted in increased gas pressure within the isolator. During operation of the scrubber, air temperature and humidity of recycled air rose significantly unless the water temperature to the unit was maintained at 15 degrees C. Overall, the chemical scrubber provided an effective adjunct to existing methods of purifying recycled air, but its application must be carefully selected in the laboratory animal facility.

Aerosols↗
PubMed1981

Psorergatic mange (Acari:Psorergatidae) of the stumptail macaque (Macaca arctoides).

Psorergates (Psorobia) sp were recovered from dermal cysts on the face, chest, and abdomen of three stumptail macaques (Macaca arctoides) in a breeding colony of research animals. The lesions were multiple and appeared as white, crusted structures measuring 2 to 10 mm in diameter. These lesions were not associated with pruritus or other clinical symptoms. The mites were embedded in the epidermis and associated with mild hyperkeratosis. A few mononuclear leukocytes were present in the dermal and subcutaneous tissues.

Animals↗
PubMed1980

Attempt to infect nonmalignant nasopharyngeal epithelial cells from humans and squirrel monkeys with Epstein-Barr virus.

With the use of Epstein-Barr virus (EBV), attempts were made to infect epithelial nasopharyngeal explant cell cultures prepared from nonmalignant human and squirrel monkey tissue. Explants were exposed to EBV from both HR-1 and B95-8 cells and examined for EBV-specific antigens by immunofluorescence and electron microscopy. Among the human specimens, no epithelial nasopharyngeal were found that could be infected with EBV. However, similar explants derived from squirrel monkey tissue were infected. The results were consistent with the hypothesis that EBV can infect at least certain explanted epithelial cells of the nasopharynx.

Animals↗
PubMed1980

Experimental toxemia in the pregnant guinea pig (Cavia porcellus).

In two groups of nonpregnant guinea pigs, uterine ischemia was produced by banding the uterine arteries and transecting the ovarian arteries. Since this procedure prevented the increase of uterine blood supply that normally occurs during pregnancy, uteroplacental ischemia resulted when the animals became pregnant. Intraarterial blood pressures were recorded immediately after surgery and again near term. Hypertension, proteinuria and elevated creatinine levels (changes similar to those of human preeclampsia) were consistently found near term in all of the banded animals that became pregnant. These findings support the view that it is possible to develop a toxemia model in the guinea pig.

Adrenal Glands↗
PubMed1980

Acidification of drinking water: its effects on selected biologic phenomena in male mice.

In this study, water acidified with either hydrocholoric or sulfuric acid to pH levels of 2.0 or 2.5 was given for 6 weeks to normal and immuno-suppressed male, random-bred mice. The pH of the drinking water remained stable for periods up to 7 days. The only significant changes produced in both immunosuppressed and normal mice with both anions were declines in weight gain and water consumption when the drinking water was acidified to a pH of 2.0. Some of the observed changes were greater in the immunosuppressed animals. These animals also showed more variation in their response to the two anions. When sulfuric-acidified water at pH 2.0 was consumed, the number of bacterial species isolated from the terminal ileum was reduced. These findings suggested that the acidification of drinking water was not innocuous and that it should be evaluated as an environmental variable whenever it is used.

Animals↗
PubMed1980

Skull fractures in infant squirrel monkeys (Saimiri sciureus).

Skull fractures resulting from trauma and leading to hemorrhage in the subdural area and brain parenchymal have been a common cause of neonatal mortality in a breeding colony of squirrel monkeys. The skull fractures may have been caused by abnormal carrying behavior by the dam or by the dam being frightened while cradling the infant during nursing.

Animals↗
PubMed1979

Effects of chronic parenteral carbohydrate administration on hepatic drug metabolism in the rat.

Effects of chronic parenteral carbohydrate administration on hepatic microsomal enzyme activity were studied in the rat. Intraperitoneal injections of either glucose or fructose (2.88 g daily for 7 days) significantly decreased hepatic cytochrome P-450 content and ethylmorphine N-demethylase and aniline hydroxylase activities. By the 5th day, cytochrome P-450 content decreased to 70-76% and ethylmorphine N-demethylase activity to 66-69% of control values. Aniline hydroxylase activity was not significantly altered until the 7th day, by which time it was 77-79% of control values. In vivo assessment of hepatic drug-metabolizing capacity using antipyrine as a test drug confirmed these decreases observed in vitro. Two major conclusions of these experiments are that such variables as time and dose of carbohydrate administration can affect the magnitude of the changes produced and that each parameter measured exhibited a distinctive pattern of change with time. Chronic carbohydrate administration produced hepatic fatty infiltration and glycogen depletion. Since all groups received identical amounts of specific nutrients, fatty infiltration was probably due to increased lipogenesis with decreased hepatic oxidative metabolism of fat. During these experiments neither hypoinsulinemia nor increased levels of cyclic AMP were observed. The molecular mechanisms responsible for hepatic glycogen depletion and decreased MFO activities remain to be established.

Aniline Hydroxylase↗
PubMed1979

The effects of selected antimicrobials on glucose transport in the rat intestine.

To determine whether oxytetracycline hydrochloride and the sodium salt of ampicillin have any adverse effects on the rat intestine, enteric enzyme levels and glucose transport rates were measured in vitro in rats. The intestinal transport of glucose did not differ significantly between control animals and those pretreated with ampicillin. For animals pretreated with oxytetracycline, the transport rates were significantly lower than those for the control group. The difference between the ampicillin and oxytetracycline groups, however, was not statistically significant. No significant differences in enteric levels of sucrase and maltase activity were found between any of the groups. The possibility that some antimicrobial agents may interfere with the absorption of nutrients suggested the need for caution in using these drugs in experimental animals.

Ampicillin↗
PubMed1979

True pregnancy toxemia (preeclampsia) in the guinea pig (Cavia porcellus).

In this study, normal nonpregnant, normal full-term pregnant, fasting ketotic and spontaneous pregnancy toxemic guinea pigs were compared to define the mechanism of this disease. In addition to conventional clinical, laboratory and pathologic studies, arterial blood pressure (thoracic and abdominal aortic) measurements and angiography were used. The results showed that in spontaneous cases of pregnancy toxemia, there is an aortic compression just caudal to the renal arteries. This compression reduced the aortic diameter by 22% of prerenal level as compared to 10% for fasting ketotic and normal pregnant guinea pigs. The aortic compression also resulted in a 30% postcompression reduction in blood pressure. No pressure differences were seen in the other groups. The postulated etiology for true toxemia of pregnancy in guinea pigs is, therefore, similar to that of man where aortic compression produces uterine ischemia and the resultant syndrome.

Alkaline Phosphatase↗
PubMed1978

Seroconversion against Epstein-Barr virus in two nonhuman primate species infected by the oropharyngeal route.

Transforming Epstein-Barr virus (EBV) was inoculated into eight squirrel monkeys (Saimiri sciureus) by spraying of viral concentrates into the nose and throat. Virus was inoculated into three marmosets (two Saguinus oedipus and one Calithrix jacchus jacchus) by direct injection into nasopharyngeal tissue. Two of these squirrel monkeys seroconverted after repeated inoculation as determined by the presence of EBV-specific antibodies to early antigen and viral capsid antigen. One squirrel monkey had antibody to EBV nuclear antigen only. One S. oedipus marmoset also seroconverted. None of the animals developed disease. The results show that seroconversion can be accomplished in squirrel monkeys after spraying of EBV into the nasopharynx, and in marmosets by direct inoculation of the virus into nasopharyngeal tissue.

Aerosols↗
PubMed1978

Basic principles in selecting animal species for research projects.

One of the most important facets of biomedical research is selecting the species of laboratory animal best suited for a particular purpose. The four major categories of animal models are experimental, spontaneous, negative, and orphan. The experimental model is the one most frequently used, but each category has a place in medical research. Once the investigator has decided which type of model the project calls for, numerous other factors must be considered: ease of handling and surgical manipulation; size, docility, and body conformation; cost of the animal and its related supplies (food, bedding, and caging); the accessibility of superficial blood vessels; and the investigator's familiarity with the various species which are available. Among the biologic factors which should be considered are resistance to natural diseases, nutritional requirements, genotype, anatomy, physiology, and biochemistry.

Animals↗
PubMed1978

Fixatives and methods of fixation in selected tissues of the laboratory rat.

The histologic appearances of tissues fixed by immersion and perfusion were compared, as well as the effects of these different fixatives: 10% neutral buffered formalin, Carnoy's fluid, and Bouin's fluid. Intravascular perfusion provided better tissue preservation than fixation by immersion. The quality of preservation by neutral buffered formalin was equal to that of Carnoy's fluid and Bouin's fluid, but the overall staining quality of the latter two was judged to be superior.

Animals↗
PubMed1978

Studies of the coagulation system and blood pressure during experimental Bolivian hemorrhagic fever in rhesus monkeys.

Experimental infection of rhesus monkeys (Macaca mulatta) with Machupo virus produced a hemorrhagic disease similar to that of Bolivian hemorrhagic fever in humans. The disease in infected animals was also characterized by the development of hypotension and coagulation abnormalities as indicated by severe thrombocytopenia and prolongation of the activated partial thromboplastin time. Evidence for disseminated intravascular coagulation was inconclusive due to the presence of normal to elevated fibrinogen levels, relatively low levels of circulating fibrin split products, and the lack of widespread fibrin thrombus deposition. The most likely causes of the hemorrhagic tendencies of this disease in infected monkeys were thrombocytopenia and decreased synthesis of coagulation and other plasma proteins due to severe hepatocellular necrosis. Hypotension may also have been due to decreased plasma protein synthesis.

Animals↗
PubMed1978

Placenta extrachorialis in the stumptailed macaque (Macaca arctoides).

Placenta extrachorialis was diagnosed in two of 56 placentas obtained from stumtailed macaques (Macaca arctoides) after elective cesarean section. The condition was characterized by the presence of an annular ring of necrotic tissue and fibrin at the margin of the villous chorion. Because these cases occurred in two of six known primiparous females, it was suggested that thte condition may account, at least in part, for the high incidence of pregnancy-related problems observed in primiparous stumptailed macaques.

Animals↗