A comparison of some cardiorespiratory effects of althesin and ketamine when used for induction of anaesthesia in patients with cardiac disease

Cardiorespiratory effects of ketamine and Althesin were measured in two groups of premedicated patients with cardiac disease. The drugs were given in clinically equivalent doses with a second dose administered about 10 min after induction. The first dose of ketamine caused a marked increase in systemic and pulmonary arterial pressure, heart rate, and central venous and wedge pressures and cardiac index. The first dose of Althesin caused a decrease in systemic arterial pressure, central venous pressure, cardiac index and heart work, but little change in heart rate. The second dose of induction agent was administered before the cardiorespiratory effects of the initial dose had resolved. The second dose of Althesin caused changes similar to those following the first dose, but less marked. The changes following the second dose of ketamine were opposite to those following the first dose.     

Protoporphyrin-induced photodynamic effects on band 3 protein of human erythrocyte membranes

In previous studies it has been shown that protoporphyrin-induced photodynamic effects on red blood cells are caused by photooxidation of amino acid residues in membrane proteins and by the subsequent covalent cross-linking of these proteins. Band 3, the anion transport protein of the red blood cell membrane, has a relatively low sensitivity to photodynamic cross-linking. This cannot be attributed to sterical factors inherent in the specific localization of band 3 in the membrane structure. Solubilized band 3, for instance, showed a similar low sensitivity to cross-linking. By extracellular chymotrypsin cleavage of band 3 into fragments of 60,000 and 35,000 daltons it could be shown that both fragments were about equally sensitive to photodynamic cross-linking. The 17,000 dalton transmembrane segment, on the other hand, was completely insensitive. Inhibition of band 3-mediated sulfate transport proceeded much faster than band 3 interpeptide cross-linking, presumably indicating that the inhibition of transport is caused by photooxidation of essential amino acid residues or intrapeptide cross-linking. A close parallel was observed between photodynamic inhibition of anion transport and decreased binding of 4,4'-diisothiocyanodihydrostilbene-2,2'-disulfonate (H2DIDS), suggesting that a photooxidation in the immediate vicinity of the H2DIDS binding site may be responsible for transport inhibition.     

Stabilization of erythrocyte shape by a chemical increase in membrane shear stiffness

Treatment of human erythrocytes with the SH oxidant, diamide, suppresses shape transformations of biconcave erythrocytes into echinocytes or stomatocytes by shape-transforming agents assumed to exert their action via the lipid phase as well as via membrane proteins. The effect of diamide on shape changes is due to a formation of inter- and intramolecular disulfide bonds in membrane proteins, and can be reversed by reduction of these disulfide bonds. A monofunctional SH reagent, N-ethylmaleimide, also stabilizes the shape of the cell. Moreover, echinocytes produced by salicylate, and stomatocytes produced by Triton X-100, can be stabilized by diamide and do not return to the biconcave shape upon removal of the shape-transforming agents. The stabilizing effect of the SH reagents is paralleled by a loss of shear-induced deformability of the erythrocytes. A model is discussed that describes the possible mechanism by which SH reagents may stabilize the shape of the cell due to an increase of membrane shear stiffness.     

Effect of sound radiation on the mixing of flows with appreciably different temperatures

The influence of acoustic oscillations on the mixing of helium and high-temperature nitrogen is investigated. The optimal radiator frequency and power ranges are determined.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 34, No. 1, pp. 67–72, January, 1978.     

Intracellular staining for HIV-specific IFN-gamma production: statistical analyses establish reproducibility and criteria for distinguishing positive responses

The cellular immune response plays a pivotal role in controlling the spread of HIV-1 infection by lysing virally infected cells and producing potent antiviral cytokines, such as interferon-gamma (IFN-gamma). Flow cytometric methods have been established to evaluate the contribution of both CD4 and CD8 subsets of T lymphocytes to the immune response to HIV by measuring their production of intracellular IFN-gamma following brief antigenic stimulation. We present a statistical treatment of intracellular cytokine staining (ICS) data that is aimed at establishing the reproducibility and robustness of this assay for use in HIV clinical trials. Comparisons of responses from HIV-seronegative and seropositive individuals were used to establish a 2-fold criterion for distinguishing positive responses with a low probability of false positives (<1%). Additional comparisons established that the reproducibility of the assay is between 1.4 and 2.0-fold depending on the magnitude of the response. Little variability was demonstrated between multiple operators for both the execution and analysis components of these experiments (<10% difference with 95% confidence). We conclude that the statistical criteria established by these analyses allow for the accurate detection and comparison of positive responses. Using these statistical criteria, the ICS assay is sufficiently robust for use in HIV-specific vaccine trials.