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PubMed1975

Can the blood-transmitted hepatitis problem be solved?

Of the approaches presently available for prevention of blood-transmitted hepatitis, most clearly effective is the avoidance of high-risk donor populations, such as most paid commercial donors. It should be emphasized that even after screening for hepatitis B antigen most paid donor blood carries with it a five-ten times higher risk of transmitting hepatitis than volunteer donor blood. Hepatitis B screening is certainly the next most useful approach. However, it has been pointed out that even with the most sensitive of current assays, as much as two-thirds of infective blood may not be eliminated. In part this is due to failure to detect hepatitis B antige, which may be detectable by such currently investigational approaches as selective antibody inhibition or testing for Core antibody. However, a major factor is the inability of hepatitis B screening to eliminate all infectious blood appears to be due to the existence of viruses other than hepatitis B that play a major role in blood-transmitted hepatitis. Tests for detection of carriers of this virus, or viruses, remain to be developed. Improved reporting of hepatitis cases with investigation and registration of implicated donors may provide an additional means for reducing the incidence of hepatitis transmission. The efficiency of additonal approaches, such as transaminase screening of donors and passive or active immunization, remains to be determined.

Animals↗
PubMed1968

The mechanism of oxygen concentration in the swim-bladder of the eel.

1. The P(O2) of venous blood from the active swim-bladder of the eel was shown to decrease with distance from the exit of the rete. This systematic change did not occur in non-secreting bladders, nor during conditions where exchange in the rete had been abolished.2. The observed change in post-rete venous P(O2) has the same rate constant as the Root-on shift.3. These findings modify the accepted model for counter-current multiplication of O(2) in the swim-bladder system by introducing rate constants for diffusion and action of acid in the rete.4. The part played by the assumed impermeability to acid of the arteriovenous partition of the rete is in the modified model replaced by the slow Root-on shift.5. The modified model contradicts the Kuhn model in that extraction of O(2) from blood is decreased at low flow and that at normal flow conditions part of the lactic acid produced can be re-used.6. Similar modifications are indicated in the model for concentration of inert gases.

Air Sacs↗
PubMed1988

An analytical solution countercurrent heat transfer between parallel vessels with a linear axial temperature gradient.

Presented in this paper is a solution for countercurrent heat exchange between two parallel vessels embedded in an infinite medium with a linear temperature gradient along the axes of the vessels. The velocity profile within the vessel is assumed to be parabolic. This solution describes the temperature field within the vessels, as well as in the tissue, and establishes that the intravessel temperature is not uniform, as is generally assumed to be the case. An explicit expression for the intervessel thermal resistance based on the difference between cup-mixed mean temperatures is derived.

Blood Vessels↗
PubMed1965

Beta-solamarine: tumor inhibitor isolated from Solanum dulcamara.

An alcoholic extract of Solanum dulcamara L., a plant widely used in folk medicine for treating cancers and warts, shows tumor-inhibitory activity against Sarcoma 180 in mice. Systematic fractionation of the extract has led to isolation and characterization of beta-solamarine as an active principle.

Alkaloids↗
PubMed1967

Renin-like enzyme in the adrenal gland.

The rabbit adrenal gland contains an enzyme which reacts with renin substrate to form a vasopressor polypeptide, probably angiotensin I. In view of the strong effects of angiotensin on secretion of aldosterone and catecholamine, this finding suggests that there may be an intra-adrenal mechanism for the control of adrenal secretions.

Adrenal Glands↗
PubMed1970

Countercurrent chromatography: liquid-liquid partition chromatography without solid support.

The liquid-liquid partition chromatographic system reported here involves a long helix of narrow-bore tubing. When the coiled tube is filled with one phase of a two-phase system and fed with the other phase, phase-interchange takes place in each turn of the coil, leaving a segment of the former phase as the stationary phase. Consequently, solutes present in either phase are subjected to a multistep partition process. The column efficiency, estimated on a separation of dinitrophenyl amino acids, is comparable to that of gas chromatography.

Amino Acids↗
PubMed1970

Countercurrent system in the renal cortex of rats.

Tubules on the surface of the renal cortex are intertwined with the capillaries. Micropuncture experiments on rats show that generally the flow of tubular fluid is against the flow of blood in the peritubular capillaries. A countercurrent flow system, therefore, exists not only in the renal papilla but also in the superficial cortex.

Animals↗
PubMed1970

Droplet countercurrent chromatography.

A new form of countercurrent chromatography, named droplet counter-current chromatography, has been developed. This all-liquid separation technique is based on the partitioning of solute between a steady stream of droplets of moving phase and a column of surrounding stationary liquid phase. Milligram quantities of dinitrophenyl (DNP) amino acids were separated with an efficiency comparable to that of gas chromatography.

Alanine↗
PubMed1970

Panting in dogs: unidirectional air flow over evaporative surfaces.

In dogs which are panting due to a heat load, most of the respired air enters through the nose and leaves through the mouth. Different patterns of flow are, however, possible. The unidirectional flow over the evaporative (nasal) surfaces is an important mechanism for regulating the amount of heat dissipated in panting.

Air↗
PubMed1970

Polypeptide with broad biological activity: isolation from small intestine.

A polypeptide, which has potent and diverse biological action-including systemic vasodilation, hypotension, increased cardiac output, respiratory stimulation, and hyperglycemia-was isolated from the small intestine of the hog. The peptide has 28 amino acid residues and is chemically distinct from the kinins, "substance P," glucagon, and secretin.

Amino Acids↗
PubMed1983

A survey of separative techniques.

Separative science has recently undergone numerous advances. This article discusses many developments and trends in liquid, ion, gas, and countercurrent chromatography, field-flow fractionation, and electrophoresis.

Chromatography, Gas↗
PubMed1981

Larvae of air-breathing fishes as countercurrent flow devices in hypoxic environments.

Larvae of the air-breathing teleost fish Monopterus are frequently exposed to periods of critical hypoxia, which they can survive because they have (i) dense capillary networks in the skin, (ii) a small blood-water barrier, (iii) an active pectoral fin mechanism that generates a posteriorly directed respiratory water current originating from the oxygen-rich surface layer, and (iv) a principal flow of blood that runs countercurrent to the water stream. Experimental data show that the larva as a whole is a functional analog of a fish gill lamella and that similar adaptive mechanisms are present in larvae of ancient fishes and some modern teleosts inhabiting permanently or periodically hypoxic waters.

Animals↗
PubMed1975

Immune response to hepatitis B surface antigen.

A total of 69 persons were investigated for assessment of cell-mediated and humoral immunity to hepatitis B surface antigen (HBsAg). Three groups, each consisting of 20 normal persons, 20HBsAg carriers, and 20 convalescent hepatitis B patients, were studied for HBsAg, anti-HBs, and leukocyte migration inhibition with purified HBsAg. Sequential sampling if an additional group of nine acute hepatitis B patients defined the cellular and humoral immune response to HBsAg. The antigen was eliminated rapidly by mounting of cell-mediated immune response detectable for a limited period, followed by antibody response in relatively few patients moore than 3 months after clearance of circulating HBsAg.

Antibody Formation↗