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Biomedical subjects

W G Martin

Publications and source records attributed to W G Martin.

At least 19 recordsLinked to original sources
PubMed1997

[Age dependence of cerebral Tc-99m-ECD distribution between preschool and school-age children and adults].

AIM: This present study deals with the question whether normal distribution of local cerebral blood flow (ICBF) agents in adults can be transferred to the age group of 4 to 15 years old children. METHODS: 23 children (age: 4-15 years, mean 11 +/- 3 y) (group I) and 10 adults (age: 27-56 years, mean 45 +/- 10 y) (group II) without evidence of cerebrovascular disease or other brain diseases underwent Tc-99m-ECD-SPECT imaging. Counts in the cortical ROIs were related to those of cerebellar ROIs (= 100%). RESULTS: In group I, relative cortical activity exceeded that of group II, particularly in parietal (107.6 +/- 9.8 vs. 84.1 +/- 12.4%), frontal (97.7 +/- 6.7 vs. 79.4 +/- 8.9%), left temporal areas (99.7 +/- 7.4 vs. 84.9 +/- 10.1%) and in the singular cortex (112.1 +/- 9.1 vs. 95.9 +/- 10.1%, p < 0.05). Cerebral activity uptake/injected dose/acquisition period was linearly correlated with age in group I (r = -0.78, p < 0.001). There was also a correlation of the relative local count density with age in 5 parietal ROIs (r = -0.42 to -0.57), in 2 frontal ROIs (r = -0.48), in 7 temporal ROIs (r = -0.42 to -0.58) and in 2 occipital ROIs (r = -0.44). In 14 cortical regions relative counts differed when subgroups of children aged 4-10 and 11-15 years were analysed. CONCLUSION: There are systematic differences between 4 to 15 years old children and adults regarding the normal distribution of ICBF. Diagnostic use of perfusion agents has to consider the respective age-adjusted normal flow maps; respective normal ranges should be determined for age groups of 4-10 and of 11-15 years separately.

Adolescent↗
PubMed1993

Estrogen enhancement of Ca-, Mg-, and Ca-Mg-stimulated adenosine triphosphatase activity in the chick shell gland.

The effect of 17 beta-estradiol (E2) on Ca-, Mg-, and Ca-Mg-ATPase activity was investigated in the shell gland of 6-week-old chicks. In the first study, each of 42 birds was implanted with three E2 (Compudose-200) pellets. An additional 6 sham-implanted birds served as controls for measurements of body weight and concentrations of E2 and Ca in plasma. The activities of Mg-, Ca-, and Ca-Mg-ATPase peaked coincident with maximum plasma E2 concentrations 8 days after implantation and then progressively declined in concert with the decline in plasma E2. By 29 days after implantation, the ATPase activities were similar to those measured in birds whose E2 pellets had been removed for 11 days. Concentrations of plasma E2 dropped from peak values of 1676 +/- 317 at Day 8 to 611 +/- 180 pg/ml at Day 29. When birds whose E2 pellets had been removed were reimplanted with three pellets per bird, plasma E2 again increased to 1637 +/- 227 pg/ml. ATPase activity in these reimplanted birds also was greater (P < 0.05) than activities measured in E2-removed or E2-maintained birds. In a second study the Ca-ATPase Km and Vmax were determined in E2-implanted chicks (three pellets per bird) and compared to E2-withdrawn chicks. Five days after reimplantation of chicks with E2, there was a significant increase in both Vmax (3.38 +/- 0.21 vs 2.37 +/- 0.28 micrograms Pi/mg protein/min; P < 0.05) and Km (0.31 +/- 0.02 vs 0.25 +/- 0.01 mM Ca; P < .01).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Taurine regulation of Ca2+ uptake and (Ca(2+)+Mg2+)-ATPase in developing chick B-cells.

1. The objective of the present study was to determine the effect of age and taurine on chick B cell calcium uptake and membrane (Ca(2+)+Mg2+)-ATPase activity in 1-4-week-old chicks. 2. The calcium uptake rate decreased with age (P < 0.05) and was further decreased by taurine (P < 0.05). 3. (Ca(2+)+Mg2+)-ATPase activity increased with age (P < 0.05) and was stimulated by taurine (P < 0.05). 4. The data demonstrate that the flux of calcium across the B-cell membrane changes during early post-hatch development, and that taurine regulates both the influx and efflux of calcium in chick B-cells.

Animals↗
PubMed1993

The effect of taurine on the incorporation of thymidine by chick B cells.

1. This study was conducted to determine the effect of extracellular taurine on chick B cell proliferation as measured by the incorporation of [3H] thymidine. 2. B cells were cultured in RPMI-1640 media containing bacterial lipopolysaccharide and either 0 or 100 microM taurine. 3. Thymidine incorporation was significantly increased in the presence of 100 microM extracellular taurine. 4. These results suggest a role for taurine in the chick B cell proliferation process.

Animals↗
PubMed1992

[The effect of acute cellular rejection on liver function following orthoptic liver transplantation. Quantitative functional studies with the 14C-aminopyrine breath test].

To test the effect of acute cellular rejection on liver function as represented by cytochrome-P-450 enzyme activity, the 14C-aminopyrine breath test (ABT) was performed prospectively in 46 patients (31 men, 15 women; mean age 48 [15-66] years) who had undergone a total of 50 orthotopic liver transplantations. Routine biochemical tests were performed daily until the 30th postoperative day, while the ABT was done daily on days 1-10 and three times weekly on days 11-30, and liver puncture biopsies were obtained once weekly or more often if there was clinical suspicion of rejection. Histologically confirmed cellular rejection occurred within the stated period of observation in eight patients (five women, three men; median age 45 [18-59] years). Results of routine laboratory tests (transaminases, bilirubin, thromboplastin time), as well as bile-flow and body temperature, did not vary uniformly. On the other hand, results of ABT at the time of rejection showed a decrease in all patients by an average of 65% (P < 0.01). Changes in the ABT preceded those in other tests by 1-2 days in four patients, being the only measurable functional abnormality in one. All rejection episodes responded to glucocorticoid pulse-treatment (three times 1 g methyl-prednisolone). Using ABT results as criterion, liver function became normal after the glucocorticoid injection within 4-11 days. These data indicate that the ABT is suitable in the routine monitoring of transplant function, thus facilitating early diagnosis and controlled treatment of acute cellular rejection.

Acute Disease↗
PubMed1992

Taurine flux in chicken erythrocytes.

1. The intracellular taurine concentration in chick erythrocytes increased with age. 2. Erythrocyte taurine influx and efflux rates increased with age. 3. Erythrocyte taurine influx decreased when the extracellular sodium concentration was below normal physiological concentrations. 4. Under hypo-osmotic conditions, taurine efflux from erythrocytes increased. 5. The data suggest that chick erythrocyte taurine metabolism changes during early post-hatch development and that one taurine function may be as an osmoregulator.

Aging↗
PubMed1992

Taurine uptake into chick B cells.

The objective of the present study was to determine whether chick B cells possess a specific transport system for taurine. The Bursa of Fabricius was isolated from newly hatched to 6-week-old chicks and an enriched fraction (86.2%) of B cells was isolated. The chick B cells maintained a high intracellular taurine concentration (0.8-1.12 mM) that decreased with age. The B cells exhibited carrier-mediated and simple diffusion uptake components, but only the carrier-mediated component increased with age. Inhibitor studies indicated taurine uptake was sodium and energy dependent. The data demonstrate that chick B cells possess a specialized taurine transport system and the activity of this system changes during posthatch B cell development.

Aging↗
PubMed1991

Taurine uptake in chicken leukocytes and erythrocytes.

1. The intracellular taurine concentration and rate of taurine uptake of chicken erythrocytes and two leukocyte populations were determined from one to six weeks of age. 2. Plasma taurine concentrations increased significantly from the time of hatching to week 2 and remained constant thereafter. 3. Intracellular taurine concentrations in both leukocyte populations increased significantly with age without any significant change in the erythrocytes. 4. Taurine uptake rate for erythrocytes was significantly higher at weeks 1-3 while both leukocyte populations showed no significant change during the six week period studied.

Animals↗
PubMed1991

Taurine content of isolated rat alveolar type I cells.

1. Rat alveolar type I cells were isolated by enzymatic digestion and purified by centrifugal elutriation and specific surface adsorption. 2. The identity of the harvested cells was confirmed using electronic cell sizing and transmission electron microscopy. 3. Purified cell preparations contained 4.6 +/- 2.3 x 10(6) type I cells/rat lung with a purity of 79 +/- 3%. 4. Isolated type I cells exhibited the following characteristics: mean cell volume = 716 +/- 48 microns 3; diameter = 11.1 +/- 0.7 microns; and cell water content = 0.50 +/- 0.03 microliter/10(6) cells. 5. Taurine content of these alveolar type I cells was measured by HPLC. 6. The intracellular taurine concentration of type I cells was 0.14 +/- 0.07 mM, a value close to that of plasma (0.1 mM).

Animals↗
PubMed1990

Effects of in vitro ozone exposure on peroxidative damage, membrane leakage, and taurine content of rat alveolar macrophages.

Rat alveolar macrophages (AM) were isolated by pulmonary lavage, allowed to adhere to a tissue culture flask, and then exposed to 0.45 +/- 0.05 ppm ozone. After exposures ranging from 0 to 60 min, the medium was decanted and cells were harvested. Cells were assayed for oxidant damage and media analyzed for leakage of intracellular components. Increasing length of exposure to ozone resulted in a decreased number of adherent AM and decreased cell viability. Resting and zymosan-stimulated chemiluminescence increased immediately after ozone exposure and reached a maximum at 15-30 min, then declined to initial levels after 60 min of ozone exposure. Lipid peroxidation and leakage of protein and K+ ions increased with increasing length of exposure to ozone, while leakage of reduced and oxidized glutathione increased through 30 min, then declined (reduced) or leveled off (oxidized). Activity of the Na+/K+ ATPase decreased with time while intracellular taurine concentration exhibited an initial rise, peaked at 30 min, and then returned to the untreated level. Leakage of taurine into the medium increased with time of exposure, suggesting that exposure of AM to ozone results in a shift from bound to free intracellular taurine. These data indicate that in vitro exposure of AM to ozone results in a time-dependent alteration of cell function, membrane integrity, and viability.

Adenosine Triphosphatases↗
PubMed1990

Calcium transport in chicken leukocytes and erythrocytes.

1. In the present study, Ca2+ uptake and Ca2(+)-ATPase activity of two different chicken leukocyte populations and erythrocytes isolated from 1- to 6-week-old chickens were determined. 2. The Ca2(+)-ATPase activity of the two leukocyte populations significantly increased at 3 weeks of age. Erythrocyte Ca2(+)-ATPase activity significantly increased at 2 weeks of age. 3. Calcium transport activities into the two leukocyte populations did not differ significantly with age.

Aging↗
PubMed1989

Taurine uptake by isolated alveolar macrophages and type II cells.

Evidence suggests that taurine may protect cellular membranes against oxidants (Gordon et al., Am. J. Pathol. 125: 585-600, 1986). The present study was conducted to determine if alveolar macrophages and type II cells (which are relatively resistant to oxidant injury) possess a specialized transport system for the accumulation of taurine. The results indicate that both cell types contain more taurine than plasma or whole lung. Taurine influx exhibited both carrier-mediated and simple diffusion components. Carrier-mediated uptake displayed saturation kinetics (Km = 26.3 and 22.5 microM, while Vmax = 33.2 and 4.9 pmol.10(6) cells-1.min-1 for macrophages and type II cells, respectively). Taurine uptake was dependent on extracellular sodium and inhibited by metabolic inhibitors or ouabain. Total taurine uptake by type II cells was lower than that of alveolar macrophages. However, type II cells exhibited a higher intercellular concentration of taurine (14 vs. 4 mM) because of a higher ratio of carrier-mediated uptake to leakage than with alveolar macrophages. It is possible that this specialized transport system for taurine uptake may lend these cells resistant to oxidant injury.

Animals↗
PubMed1988

Reversed-phase high-performance liquid chromatography technique for taurine quantitation.

Taurine (2-aminoethanesulfonic acid) was quantitated by reversed-phase chromatography on a C18 Resolve column using a linear gradient of 9-11% methanol in water. Glutamine was used as the internal standard. Pre-column derivatization of the amino acid with o-phthalaldehyde allowed the detection of as little as 0.1 pmol taurine. Dual ion-exchange column chromatography was employed to remove other amino acids and metabolic precursors of taurine from the samples. Cysteic acid and cysteine sulfinic acid did not interfere with taurine analysis by the high-performance liquid chromatographic method. For sample deproteinization, boiling and picric acid precipitation were used. Recovery of taurine averaged 93.5 +/- 5.0% (means +/- standard error of the mean) from standard solutions and was not affected by the method of deproteinization. Using this procedure, plasma taurine concentrations for the rat and chick were determined to be 100.7 +/- 13.1 microM and 108.0 +/- 0.3 microM, respectively. Recovery of taurine from plasma samples averaged 97.2 +/- 4.7%.

Animals↗
PubMed1988

Changes in intestinal calcium transport and binding in magnesium-deficient chicks.

Disruption of membrane integrity and function has been reported previously as one of the predominant effects of magnesium deficiency. In the current study, we have examined the uptake and binding of calcium by intestinal brush border membrane vesicles from chicks and investigated the effects of Mg deficiency on these processes. Both uptake and binding of calcium were significantly decreased in the membrane vesicles from animals given the magnesium-deficient diet. In addition, the calcium-binding activity of proteins isolated by chromatography on DE-52 cellulose of mucosal extracts was altered by the magnesium deficiency.

Animals↗
PubMed1984

Immobilization of isolated and cellular hydrogenase of D. desulfuricans in radiation-polymerized polyacrylamides.

Purified hydrogenase from Desulfovibrio desulfuricans was immobilized either by entrapment or absorption onto porous neutral and charged acrylamide beads. Surface absorption and crosslinking on the beads resulted in a high hydrogenase activity and a good immobilization coefficient compared to the enzyme and whole cells entrapped in the same matrix. Maximum enzyme activity (citrate-phosphate buffer) was shifted to pH 6.5 upon immobilization in contrast to 6.0 for the free enzyme and the range of 6-7 for whole cells. Both the purified enzyme and whole cells were most active when held in neutral matrices. Immobilization improved the temperature stability (65 degrees C) and long term storage (4 degrees C) of the hydrogenase activity of both the purified enzyme and whole cells.

Acrylic Resins↗