Effect of hypoxia on immediate ventilatory load response in dogs.

The effective elastance of the respiratory system (which has been previously shown to provide an index of the ability of the respiratory musculature to compensate rapidly for transient mechanical ventilatory loads) was measured in six hypoxic dogs to determine whether hypoxia hindered immediate load-compensatory mechanisms. The effective elastance value was computed from measurements of control tidal volume and the pressure developed at the airway opening during the first inspiratory effort following airway occlusion at FRC. The mean effective elastance was 197 cmH2O/l while the animals were breathing room air and did not change significantly when the animals were rendered hypoxic by reducing the inspired oxygen concentration, in five dogs, or by controlled hemorrhage, in two dogs. It was concluded that inasmuch as effective elastance measurements remain constant during hypoxia, the stability of ventilation is not significantly impaired in this situation.     

Ethanol vapours above lacrimal fluid in the rabbit

Ethanol was administered intravenously to rabbits. The concentration of ethanol, determined by gas chromatographic analysis, in lacrimal fluid was shown to reflect the concentration in plasma. The vapour above lacrimal fluid was analyzed in situ by the use of a small resistivity sensor that measures ethanol vapours. After a dose of approximately 750 mg/kg, the metabolic rates of ethanol determined by gas chromatographic analysis of plasma (226 +/- 13 mg.kg-1.h-1) and by eye ethanol vapour analysis (210 +/- 8 mg.kg-1.h-1) were virtually identical. The data suggest that ethanol eye vapour analysis may be an attractive, noninvasive method for the determination of ethanol in animals.     

Antigenic determinants expressed by human C4 allotypes; a study of 325 families provides evidence for the structural antigenic model

The antigenic determinants of human C4 have been defined by human IgG antisera, Rodgers (Rg) and Chido (Ch), in hemagglutination-inhibition assays (HAI). Eight (2 Rg and 6 Ch) are of high frequency, > 90% , and 1, WH, is of low frequency, 15 %. The phenotypic combinations are complex; generally, C4A expresses Rg, and C4B has Ch, but reverse antigenicities have been established both by HAI and by sequence data of selected C4 allotypes. A study of 325 families provides data on the antigenic expression of each C4 allotype and demonstrates strong associations. A structural model for the antigenic determinants of C4 proteins has been proposed and is completely supported by the family material. Of the 16 possible antigenic combinations for C4 proteins, only 3 are undetected. A new Ch combination has been recorded in two French families. The reported sequence variation within the C4d region can account for the antigenic determinants but leaves the location of electrophoretic variation in C4 still unclear.     

Lymphocyte activation and serine-esterase induction following recombinant interleukin-2 infusion for lymphomas and acute leukaemias

Summary C57BL mice inoculated with radiation leukemia virus (RadLV) develop preleukemic cells long before the onset of leukemia. These cells are potentially immunogenic but fail to elicit an immune response in the host because of the appearance of virus-specific suppressor T cells. We have studied the effect of polysaccharide K (PSK) on the generation of RadLV-specific cell-mediated immune responses in vitro. Long-term exposure to PSK in culture potentiated the ability of immunized T cells to respond to a RadLV-induced lymphoma. It also abrogated the suppressive activity of suppressor T cells and simultaneously boosted the ability of reactive T cells to respond. The dual immunostimulating activity of PSK resulted in the generation of T cytotoxic lymphocytes that could lyse lymphoma cells in vitro. The results suggest that PSK could be used as a prophylactic immune response modifier in preleukemia.     

Subgroups in theHordeum patagonicum complex (Poaceae)

Seeds of theHordeum patagonicum complex were collected from the field and grown in the greenhouse. The aim was to take a sample of members of the complex, and on the basis of the phenotypic similarities in some morphological and physiological characters, determine whether distinct groups exist. When cluster analyses, to generate hypotheses, and orthodox statistical procedures, for hypotheses obtained a priori, were applied to the reproductive morphology, germination and flowering patterns, onlyH. patagonicum subsp.magellanicum, out of the five recognized taxa, could be distinguished consistently. The remaining four taxa, which overlapped considerably, could be re-formed into three groups whose centroids were different but whose ranges of variation were not distinct from each other. We conclude that the highly cross-compatible members of theH. patagonicum complex, first defined as species and later redefined as subspecies are probably no more than biotypes.     

Semiautomated analysis of ethanol and acetate in human plasma by head space gas chromatography

Plasma samples (0.5 mL) were analyzed for ethanol and acetate by head space gas chromatography using a Porapak QS column (80-100 mesh). Acetate was esterified to methyl acetate simply by the addition of acidified methanol. The analytical ranges were 1.61-103 and 0.05-1.9 mM for ethanol and acetate, respectively. The within-run coefficients of variation did not exceed 4.7% for acetate and 2.7% for ethanol. After the oral administration of ethanol to two healthy human subjects, the concentration versus time profiles of plasma ethanol and acetate were determined. Acetate concentrations (0.4-0.9 mM) remained quite constant while ethanol was being metabolized and appeared not to be affected by the concentration of ethanol in the range 3-18 mM. The advantages of the method are speed and simplicity.     

A note on the production and use of antisera for the detection of part-digested sticklebacks in predator stomach-content samples

Preliminary experiments indicate that serological techniques provide a useful method of identifying specific prey antigens from the stomach contents of fish predators. Problems with cross-reacting antigens from different prey species can be reduced by absorbing anti-sera with tissue extracts of the cross-reacting species. Very small volumes of part-digested prey tissue are sufficient for identification of the prey species when using agarose diffusion plates (Ouchterlony tests).     

Increased loss and decreased synthesis of hepatic glutathione after acute ethanol administration. Turnover studies.

The effect of acute ethanol administration on rates of synthesis and utilization of hepatic glutathione (GSH) was studied in rats after a pulse of [35S]cysteine. A 35% decrease in hepatic GSH content 5h after administration of 4 g of ethanol/kg body wt. was accompanied by a 33% increase in the rate of GSH utilization. The decrease occurred without increases in hepatic oxidized glutathione (GSSG) or in the GSH/GSSG ratio. The rate of non-enzymic condensation of GSH with acetaldehyde could account for only 6% of the rate of hepatic GSH disappearance. The increased loss of [35S]GSH induced by ethanol was not accompanied by an increased turnover; rather, a 30% inhibition of GSH synthesis balanced the increased rate of loss, leaving the turnover rate unchanged. The rate of acetaldehyde condensation with cysteine in vitro occurred at about one-third of the rate of GSH loss in ethanol-treated animals. However, ethanol induced only a minor decrease in liver cysteine content, which did not precede, but followed, the decrease in GSH. The characteristics of 2-methylthiazolidine-4-carboxylic acid, the condensation product between acetaldehyde and cysteine, were studied and methodologies were developed to determine its presence in tissues. It was not found in the liver of ethanol-treated animals. Ethanol administration led to a marked increase (47%) in plasma GSH in the post-hepatic inferior vena cava, but not in its pre-hepatic segment. Data suggest that an increased loss of GSH from the liver constitutes an important mechanism for the decrease in GSH induced by ethanol. In addition, an inhibition of GSH synthesis is observed.     

The effects of putative amino acid neurotransmitters on somata isolated from neurons of the locust central nervous system

Changes in spike frequency, membrane potential and input resistance of somata freshly isolated from neurons in the metathoracic ganglia of adult locusts (Schistocerca gregaria) during bath and ionophoretic application of putative amino acid transmitters and analogues were studied using intracellular techniques. gamma-Aminobutyrate, glycine, taurine, cysteine and DL-ibotenate hyperpolarized the isolated soma, the response to kainic acid was depolarizing whereas L-glutamate and L-aspartate evoked a variety of potential changes. All of these compounds reduced the input resistance of the isolated soma. Ionophoretic studies showed that the receptors for L-glutamate and gamma-aminobutyrate are diffusely distributed over the somal surface.     

Locust nymphal neurones in culture: a new technique for studying the physiology and pharmacology of insect central neurones

A new technique for studying the physiology and pharmacology of locust central neurones is described. Somata isolated from neurones in the meso and metathoracic ganglia of third instar locusts (Schistocerca gregaria) were maintained for up to 4 weeks in co-culture (monolayer) with embryonic locust neurones. Most of the cultured cells became multipolar but a few were monopolar like their in vivo counterparts. They had diameters of 40-80 microns and "clean" (glial free) surface membranes. Cells 6-14 days in vitro were depolarized by acetylcholine and usually hyperpolarized by gamma-aminobutyrate, taurine and glycine. L-Glutamate and L-aspartate were inactive but further pharmacological studies are required to confirm this. Cultured larval neurones should provide excellent opportunities to study the molecular basis for drug-receptor interactions and voltage-sensitive membrane channels using the patch clamp technique.