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Biomedical subjects

A Baz

Publications and source records attributed to A Baz.

27 records · Page 2Linked to original sources
PubMed1989

Lack of interspecies barriers in anti-Id stimulated antibody production against Echinococcus granulosus antigens.

Polyclonal human anti-hydatid antibodies were affinity purified from a hydatid patient serum and used to produce a rabbit anti-idiotypic serum. These anti-Id antibodies cross-reacted in ELISA with sera from 11 of 12 hydatid patients studied and with 13 infected or immunized mice sera. All mice primed and boosted with anti-Id produced anti-hydatid antibodies in the primary response and exhibited an increase in antibody titre after a booster injection. The same effect was observed with mice primed with antigen and boosted with anti-Id, although these mice exhibited higher antibody titres. A significant idiotype repertoire is shared by anti-hydatid antibodies produced by different individuals of the same or different species, and anti-Id raised against those antibodies behave as surrogate antigens producing a normal primary and secondary response in animals of different species from that used to isolate the Id.

Animals↗
PubMed1986

Effect of intravascular bubbles on perfusate flow and gas elimination rates following simulated decompression of a model tissue.

This study deals with the monitoring of the elimination rates of gases from a porous cylindrical model of the human tissue during simulated single-stop decompression schedules. The data suggest the presence of an optimal decompression stop for each dive at which the gas elimination rate is maximum. The effect of varying the flow rate and the viscosity of the liquid perfusing the tissue model on the elimination rate is determined for different diving conditions. Although this study has been carried out on a single tissue model, it provides means for explaining some of the physiological phenomena observed in human tissues.

Decompression Sickness↗
PubMed1979

Inert gas transport in the microcirculation: risk of isobaric supersaturation.

This paper is concerned with the theretical background and implications of isobaric supersaturation and bubble formation in the microcirculation following an abrupt shift from one inspired inert gas to another. The use of more than one inert gas, simultaneously or sequentially, has become common in diving and presents risks as well as potential benefits. A review of microcirculatory model useds, theoretical approaches to decompression, and order of magnitude calculations indicates that present empiricisms are inadequate for predicting such supersaturation phenomena. This is true whether based on the familiar assumption of perfusion-limited behavior or its diffusion-limited counterpart. The "chromatographic" model used here, which considers both perfusion and axial diffusion in tissue cylinders, shows that these combined effects can produce unexpectedly high local supersaturation. The implications include new possibilities for the experimental evaluation of gas transport models as well as practical risks of inert gas shifts in diving and certain diagnostic procedures.

Brain↗
PubMed1979

Single-tissue modeling of decompression schedules.

This paper deals with the development of a single-tissue model that simulates the uptake and elimination of inert gases by the body of a diver. The model utilizes an effective single tissue with different uptake and elimination time constants to account for the asymmetrical behavior of multiple-tissue human body models. The parameters of this effective tissue are selected according to an optimal strategy that minimizes safe deviation from the decompression requirements recommended by safe practice. The developed strategy is general in nature and can be readily applied to select the optimal parameters for a single-tissue model suitable for any dive regimen on air or mixed gas. As an illustration, the procedure is used to select the optimal tissue that best fits the Standard Air Decompression Tables recommended by the U.S. Navy. The results obtained are in close and safe agreement with the requirements of the U.S. Navy, and consistently fall in the range between the U.S. Navy and the Royal Navy tables.

Decompression↗
PubMed1975

Nitrogen elimination in man during decompression.

The effect of ambient pressure on inert gas elimination during decompression was investigated using human subjects breathing air in a dry hyperbaric chamber. This was done by measuring nitrogen recovery during three different decompression schedules following identical simulated dives. Five subjects were used, each with normal pulmonary function. In each case the simulated dives consisted of exposure for 40 min to air at 4 ATA corresponding to a depth of about 100 fsw and 28 degrees C. Following these exposures each subject was decompressed in different experiments to 50 fsw (2.515 ATA) and to 10 fsw (1.303 ATA) while breathing a mixture of 80:20 helium-oxygen. In addition, two of these subjects were denitrogenated isobarically, at 100 fsw, breathing 80:20 helium-oxygen. Significant differences in nitrogen-elimination rate were observed, with nitrogen removed most effectively at 50 fsw and least at 100 fsw. To explained these unexpected results it is tentatively suggested asymptomatic bubble formation occurred at both 10 and 50 fsw.

Decompression↗
PubMedDate not supplied

Subcellular distribution and profiles of prosomes (proteasomes-MCP) during differentiation of human lymphoblastic cell line.

The human lymphoblastoid leukemic cell line (CCRF-CEM) was induced to differentiate with phorbol 12-myristate 13-acetate (PMA). During differentiation, assessed by monitoring the cluster of differentiation (CD) profile, the prosome (proteasomes, multi-catalytic proteinase) distribution and composition were studied by microscopy, flow cytometry and Western blot analysis. Changes in prosome subunits were monitored using 3 monoclonal antibodies anti-p23K, p29K and p31K. There were changes in the subcellular distribution of prosome antigens in PMA treated cells compared to untreated cells. The amount of cytoplasmic prosomal antigens decreased during the first three days of differentiation and the membrane antigens increased; meanwhile there was an increase of p53 and no change in actin protein levels. As mitotic cyclins are degraded by the ubiquitin pathway and therefore via the prosome, the decrease observed in differentiated cells suggests that prosomes are involved in the cell cycle and thus in cell proliferation.

Antibodies, Monoclonal↗
PubMedDate not supplied

[Comparison of hydroelectrolytic exchange characterized by calculation of saturable fluxes at three levels of the rat intestine].

Using the everted sac technique, which responded, as expected, to VIP by an increase of the secretion and to glucose by an increase of the absorption, we compared the water and electrolyte movements in the jejunum, ileum and colon in rats. Identical iso-osmolar test-solutions containing increasing NaCl concentrations, placed on the serosal and mucosal sides, allowed us to quantify fluxes in the absence of initial gradient. The measured net Na and Cl fluxes were dissociated into their two components, a passive flux from serosa to mucosa and a saturable flux from mucosa to serosa. The parameters of the saturable transport, calculated for each of the intestinal parts, showed the highest J max for the ileum (58.5 microEq.g-1.h-1 for Na and 52.8 microEq.g-1.h-1 for Cl) and the lowest Km for the colon that had the highest affinity for sodium and chloride (Km 11.1 mM for Na and 7.8 mM for Cl). These data confirm the functional difference between the three intestinal parts, with an active absorption of Na and active secretion of Cl in the jejunum, an apparent coupled Na and Cl absorption in the ileum and an active absorption with high affinity for both Na and Cl in the colon.

Animals↗