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Biomedical subjects

C Hagen

Publications and source records attributed to C Hagen.

166 records · Page 10Linked to original sources
PubMed1967

Effect of reduced barometric pressure on water availability related to microbial growth.

Data obtained from Mariner IV indicate that the barometric pressure on Mars is considerably lower than previously estimated. Current estimates from Mariner IV indicate a range from 4 to 7 mb and by near infrared spectroscopy 33-56 mb. Inasmuch as the pressure has a marked influence on availability of water, this should affect the existence of Martian life. At the maximum temperatures recorded on Mars, namely 25 degrees C, a barometric pressure of 30 mb is required for the retention of free water. The lower pressure, 4 mb, would suggest that the moisture is present as a vapor above the freezing point and consequently it is not available for utilizing by living cells. The lower estimates of barometric pressure also inversely affect the carbon dioxide concentration in the Martian atmosphere. Our previous studies have demonstrated that spores of Bacillus cereus survive, germinate and grow in a simulated Martian environment (2.4% CO2, 98 mb) supplemented with moisture. The studies described in this paper were designed to determine the effect of low barometric pressures (10 to 98 mb Hg) and high concentrations of carbon dioxide (37 to 100%) in the simulated Martian environment on survival and growth of B cereus. The organism was inoculated into a felsite-limonite soil at 8% moisture level. The temperature cycles used were 8 hr at -65 degrees C and 16 hr at 25 degrees C, or 20 hr at -65 degrees C and 4 hr at 25 degrees C. The data suggest that the organism after achieving maximum growth in the simulated Martian environment (2.4% CO2, 98 mb) immediately enters into the growth phase upon reinoculation into fresh soil. These data reflect upon the possibility of contamination through air movements. Based upon currently available Martian environmental data, the probability of contamination of Mars by terrestrial micro-organisms will be discussed.

Atmosphere↗
PubMedDate not supplied

A review of endocrine changes in anorexia nervosa.

Anorexia nervosa is a syndrome of unknown etiology. It is associated with multiple endocrine abnormalities. Hypothalamic monoamines (especially serotonin), neuropeptides (especially neuropeptide Y and cholecystokinin) and leptin are involved in the regulation of human appetite, and in several ways they are changed in anorexia nervosa. However, it remains to be clarified whether the altered appetite regulation is secondary or etiologic. Increased secretion of corticotropin-releasing hormone and proopiomelanocortin seems to be secondary to starvation, however, there is evidence that it may maintain and intensify anorexia, excessive physical activity and amenorrhea. Hypothalamic amenorrhea, which is a diagnostic criterion in anorexia nervosa, is not solely related to the low body weight and exercise. Growth hormone resistance with low production of insulin-like growth factor I and high growth hormone secretion reflect the nutritional deprivation. The nutritional therapy of patients with anorexia nervosa might be improved by administering an anabolic agent such as growth hormone or insulin-like growth factor I. So far none of the endocrine abnormalities have proved to be primary, however, there is increasing evidence that some of these might participate in a vicious circle.

Anorexia Nervosa↗
PubMedDate not supplied

Rehabilitation of the communicatively impaired stroke patient.

The stroke patient who has lost the ability to communicate has lost more than the ability to talk. To one degree or another, he has lost the ability to understand his environment, the ability to structure his thought process internally in a logical and meaningful order, and the ability to formulate language in a logical and meaningful order. The ability to structure one's thoughts and ideas internally, as well as the ability to communicate them to others, are intrinsic factors in an individual's ability to motivate himself to establish a goal and to pursue the acquisition of that goal. Therefore, the successful physical rehabilitation of the stroke patient with a communication disorder rests heavily upon an understanding and a resolution of his communication problem.

Aphasia↗