Biomedical subjects

C V Paganelli

Publications and source records attributed to C V Paganelli.

4 recordsLinked to original sources

PubMed1977

Diffusion of water vapor in binary and ternary gas mixtures at increased pressures.

Diffusion of water vapor was measured at 25 degrees C in the binary systems water vapor-He and water vapor-N2 at approximately 1, 4 10, 20 and 50 atm. Diffusion was also measured in the ternary system water vapor-He-O2 in both 2%O2-98%He, and at 1 and 20 atm. At 1 atm, comparison of binary diffusion coefficients (delta) shows that water vapor diffuses 3.3 times more readily in He than in N2. Values of delta at elevated pressures were reduced in proportion to 1/p, the absolute pressure, in qualitative agreement with Chapman-Enskog theory. However, the reduction in Delta was less than predicted at pressure above 4 atm in water vapor-N2 and above 20 atm in water vapor-He. The deviations from theory are more pronounced in N2 than in He, and become larger at higher pressures. When 26% O2 is present in the ternary system water vapor-He-O2, diffusion of water vapor is reduced to about 60% of its rate in pure He. In contrast, 2% O2 in He has little effect on diffusion of water vapor.

Diffusion↗

PubMed1977

Bubble formation within decompressed hen's eggs.

Decompression sickness follows a reduction in ambient pressure and is a result of bubble formation in blood or tissues. The origin of such bubbles is the subject of considerable controversy, and a number of mechanisms have been proposed to account for them. In testing these mechanisms, freshly-laid hen's eggs provide a particularly intriguing model--namely, an intact biological system in which bubbles form readily and many of the proposed processes are excluded.

Animals↗

PubMed1977

Hana kai ii: a 17-day dry saturation dive at 18.6 ATA. III. Body fluid balance.

Comprehensive studies on body fluid balance on 5 divers were conducted during the Hana Kai II dive (17 days at 18.6 ATA and 7 days of decompression). Daily urine flow increased from about 2000 ml at 1 ATA to 2600 ml at 18.6 ATA, at 31 degrees C. This diuresis was accompanied by a reduction in urine osmolality (from 650 to 500 mOsm) and a slight increase in osmolal clearance. Endogenous creatinine clearance remained at about 173 ml/min throughout the dive. Despite such a sustained diuresis, neither daily water intake nor total body water volume changed significantly. The plasma renin activity changed little, while both plasma aldosterone concentration and urinary aldosterone excretion increased significantly during the first week at 18.6 ATA. The plasma prolactin concentration showed a significant decrease during the first 3 days at 18.6 ATA. The daily excretion of antidiuretic hormone (ADH) decreased significantly (by 40%) 4 days after compression and remained low throughout the rest of the dive. Insensible waterloss at 18.6 ATA was 35% lower than that at 1 ATA. It is suggested that the observed hyperbaric diuresis is due primarily to suppression of ADH as a result of suppression of insensible water loss.

Aldosterone↗

PubMed1975

Diffusion in the gas phase: the effects of ambient pressure and gas composition.

Gas transport across the pores of a hen's egg shell occurs by a process of diffusion in the gas phase and for any particular gas depends upon its diffusion coefficient and the pore geometry. The egg shell is thus a convenient model for measuring the diffusive permeability of the shell to a given gas species when its diffusion coefficient is altered by either a change in ambient pressure or by changing the second gas in the diffusion pathway. In this study the permeability of the shell to water vapor and O2 was inversely proportional to ambient pressures over the range of .06 to 8 atmospheres' absolute (ata). The permeability of the shell to water vapor in a He environment (KH20, He) was 2.4 times KH20, air. If KO2, N2 is taken as unity, the permeabilities of the shell to O2 in He, Ar, CO2 and SF6 are 3.38, 0.95, 0.88, and 0.52, respectively. The results are interpreted in terms of the Chapman-Enskog equation, from which binary diffusion coefficients can be predicted for given gas pairs and ambient pressures. These results also provide explantations for the structural modification of egg shells in altitude-adapted chickens, and for the reduced insensible water loss in man at high ambient pressure.

Animals↗