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Biomedical subjects

K Johansen

Publications and source records attributed to K Johansen.

At least 253 records · Page 14Linked to original sources
PubMed1975

Oxygen uptake and blood respiratory properties of the caecilian Boulengerula taitanus.

In contrast to amphibians belonging to the orders Urodela and Anura, virtually no data exist on the respiratory physiology of the more primitive Apoda. This study concerns oxygen uptake and hemoglobin function in the caecilan Boulengerula taitanus, an apodan with fossorial habits. The oxygen uptake rate resembles that of other amphibians of similar size. The blood was high O2 capacity (14 vol%) and the erythrocytes are smaller, and the red cell count is greater than in other amphibians. The oxygen affinity of whole blood is high compared to other amphibians (P50 = 28 mm Hg at 25 degrees C and pH 7.6). The oxygen equilibrium curve is sigmoid (n = 1.79) and the Bohr factor is small (deltalog P50/deltapH = - 0.21). In 'stripped' hemoglobin solutions oxygen affinity increases strongly (P50 = 3.3 mm Hg at 25 degrees C and pH 7.6) and the temperature sensitivity is high (apparent deltaH=-19.4 kcal/mole), but the ATP and pH influences are too low to account for the difference in P50 compared to whole blood. The high oxygen capacity and oxygen affinity and the low Bohr factor may have adaptive significance to this fossorial amphibian.

Adenosine Triphosphate↗
PubMed1975

A fish in extreme alkalinity.

Tilapia grahami (Boulenger), a small cichlid fish, inhabits extremely alkaline water where the total CO2 concentration exceeds 200 meq.L(-1), osmolality is about 600 mosm.L(-1), pH ranges between 9.6 and 10.5 and temperature may be 43 degrees C. Venous blood drawn anaerobically by heart puncture had pH values as high as 8.4 at 35 degrees C. A 10-15-fold bicarbonate concentration gradient exists across the gills of Tilapia. It is suggested that the uniquely high and variable blood pH results when blood in the gills are exposed to water in which free CO2 can hardly exist. Blood CO2 must be correspondingly low resulting in pH values hitherto unknown to occur in vertebrates.

Acid-Base Equilibrium↗
PubMed1975

Adaptive tolerance of fish myocardium to hypercapnic acidosis.

Isometric, electrically paced strips of cardiac ventricle from two species of fish (plaice, Pleuronectes platessa; cod, Gadus morrhua) with different tolerance to hypoxia were compared with respect to effects of hypercapnic acidosis. Acidosis was induced by altering the equilibrating gas mixture for the muscle strip chamber from 3% CO2 in 97% 02 to 15% CO2 in 85% O2. The pH was varied further by changing the NaHCO3 content of the Cortland-Ringer solution used in the muscle chamber. After onset of acidosis with the highest buffer value of the Cortland-Ringer solution (35.7 mM NaHCO3), the force decay was similar for the initial 10 min of exposure to high Pco2. Subsequently the cod heart continued to lose force at the same rate, whereas the plaice heart regained a cardiac contractile force that after 40 min even exceeded prehypercapnic values. When buffer values were varied by changing the bicarbonate content of the Cortland-Ringer solution in steps from 0.0 to 35.7 mM NaHCO3, the cod heart showed steep force decays at all buffer values during hypercapnic acidosis. The plaice heart showed a similar decline at low buffer values but at a bicarbonate concentration above 23.8 mM NaHCO3, the initial force decline was reversed and prehypercapnic force restored.

Acid-Base Equilibrium↗
PubMed1975

The colloid osmotic pressures of invertebrate body fluids.

Colloid osmotic pressures of the body fluids of twenty invertebrate species were measured directly. The results, which are generally lower than predicted values for the same species, pertain to several physiological questions: (1) they do not quantitatively explain the frequently observed hyperosmoticity of body fluids in species believed to be osmoconformers, indicating that the condition cannot be merely a consequence of a Gibbs-Donnan equilibrium; (2) the excess of hydrostatic over colloid osmotic pressure is very small. This result supports the hypothesis that the oxygen transport function of bloods with extracellular haemocyanins and haem proteins is limited by their colligative properties; (3) the pressure relationships and the absence of colloid osmotic activity in urine indicates that filtration contributes to urine formation in several species.

Animals↗
PubMed1974

Maternal HL-A antibodies and fetal sex.

In a study of 960 pregnancies a significantly higher male to female birth ratio was found among primigravidae who developed HL-A antibodies, which was highest where these were monospecific. In the whole group male births predominated in women with antibodies to HL-A 1 and 11 (first locus) and HL-A 5, 12, and 13 and TYT (second locus).

Antibody Formation↗