16 research outputs found
A RADIOMETRIC ASSAY FOR GANGLIOSIDE SIALIDASE APPLIED TO THE DETERMINATION OF THE ENZYME SUBCELLULAR LOCATION IN CULTURED HUMAN-FIBROBLASTS
No full textA radiometric method for the assay of ganglioside sialidase in cultured human fibroblasts was set up. As substrate, highly radioactive (1.28 Ci/mmol) ganglioside GD1a isotopically tritium-labeled at carbon C-3 of the long chain base was employed; the liberated, and TLC separated [3H]GM1 was determined by computer-assisted radiochromatoscanning. Under experimental conditions that provided a low and quite acceptable (4-5%) coefficient of variation, the detection limit of the method was 0.1 nmol of liberated GM1, using as low as 10 μg of fibroblast homogenate as protein. The detection limit could be lowered to 0.02-0.03 nmol, adopting conditions that, however, carried a higher analytical error (coefficient of variation over 10%). The content of ganglioside sialidase in human fibroblasts cultured in 75-cm2 plastic flasks was 5.8 ∓ 2.5 (SD) nmol liberated GM1 h-1 mg protein-1. Subfractionation studies performed on fibroblast homogenate showed that the ganglioside sialidase was mainly associated with the light membrane subfraction that was rich in plasma and intracellular membranes. This subfraction displayed almost no sialidase activity on the artificial substrate 4-methylumbelliferyl-d-N-acetylneuraminic acid. A small but measurable ganglioside sialidase activity was also present in the lysosome-enriched subfraction, which contained a very high sialidase activity on the above artificial substrate. All this supports the hypothesis that human fibroblasts contain sialidases with different subcellular location and substrate specificity. Particularly, the sialidase acting on gangliosides seems to have two sites of subcellular location, a major one at the level of plasma membranes and/or intracellular organelles functionally related with the plasma membranes and a minor one in the lysosomes
Transintestinal transport of L-carnitine and carnitine esters in the rat
No full textL-carnitine is transported in small intestine via a carrier-mediate active transport system. At pharmacological doses a diffusional component is predominant
L-carnitine and carnitine ester transport in the rat small intestine
No full textL-Carnitine and its esters (acetyl-L-carnitine and propionyl-L-carnitine) at pharmacological doses (1,5 and 100 mM) are absorbed by the rat jejunum by simple diffusion. Partition coefficients of carnitin eesters determined in lipophilic media (diethyl ether/water and olive oil/water) are greater than that of L-carnitine. It would therefore seem that esters diffuse more easily through th elipid component of the intestinal barrier. The transport of acetyl- and propionyl-L-carnitine at pharmacological doses seems to be linearly and positively correlated with K+ transport but not with Na+ transport
HEMODYNAMIC AND METABOLIC-ACTIVITIES OF PROPIONYL-L-CARNITINE IN RATS WITH PRESSURE-OVERLOAD CARDIAC-HYPERTROPHY
No full textEvidence has been put forth that a number of human and experimental cardiomyopathies are associated with a lower myocardial carnitine content. This study was performed to test the hypothesis that the correction of carnitine deficiency by a naturally occurring carnitine derivative, propionyl-L-carnitine (PLC), may improve cardiac function. Repeated administration of PLC was compared to saline with respect to cardiac function in rats with pressure-overload cardiac hypertrophy and low myocardial carnitine levels. Cardiac hypertrophy was induced by abdominal aorta constriction in rats. Separate groups of rats were used for (a) determination of myocardial carnitine content, (b) evaluation of in vivo hemodynamics, and (c) evaluation of performance and metabolic state of Langendorff perfused hearts. Results showed the following: (i) The myocardial carnitine content was inversely correlated to cardiac hypertrophy (r = 0.68, p 1,400 mg, the effect of PLC on CO, CW, SV, SW, and total peripheral resistance (TPR) was significantly different from that of saline (CO, CW, SV, and SW, p < 0.005 each; TPR, p < 0.05). The effect was observed 24 h after the first PLC administration and significantly diminished following a 4 day suspension of the treatment. (iii) Perfused hearts from PLC-treated rats displayed a significantly lower left ventricular end- diastolic pressure (p < 0.01) and greater relaxation rate (p < 0.05) than those from control rats. Moreover, in PLC-treated hearts, the content of creatine phosphate, ATP, and total adenine nucleotides (ATP + ADP + AMP; TAN) was significantly increased (CP, p < 0.05; ATP and TAN, p < 0.01 vs. control). These data show that PLC exerts a stimulatory activity on hearts with hypertrophy and low carnitine content, implying that carnitine deficiency may contribute to the depression of cardiac function in this model
Plasma concentration, urinary excretion and renal clearance of L-carnitine during pregnancy: a reversible secondary L-carnitine deficiency.
No full textEffects of enalapril and isradipine alone and in combination on blood pressure, renal function and echocardiographic parameters in mild hypertension.
No full textAIMS AND METHODS: A study was carried out to evaluate the influence of
antihypertensive treatment with combined low doses of enalapril plus isradipine
(5+5 mg daily) compared with those of either drug at a higher dose level (10 mg
daily) by double-blind, three-way crossover study (balanced Latin square design)
in 102 subjects (mean age 51.9 +/- 7.42 years) with essential hypertension. Left
ventricular mass and function were evaluated by M-B mode echocardiography, renal
function by glomerular filtration rate (GFR) and by serum and 24-h urinary Na+
and K+ during wash-out period and after 24 weeks of treatment.
RESULTS: The supine blood pressure for subjects given placebo was 171/103 mmHg.
After 24 weeks of treatment, systolic and diastolic supine blood pressure were
significantly lower with 5 mg isradipine plus 5 mg enalapril (134/84 mmHg) than
with 10 mg enalapril (137/84 mmHg) or with 10 mg isradipine (144/85 mmHg). Left
ventricular posterior wall and septal thickness were significantly and similarly
reduced in all groups. Left ventricular systolic and diastolic end diameters were
not significantly changed. Left ventricular mass (LVM) was significantly reduced
in E plus I group and enalapril group. GFR was not significantly altered. The
24-h urinary Na+ significantly increased with enalapril, more so than isradipine.
The combination was tolerated better than either monotherapy. We observed no
clinically significant changes in laboratory variables including blood
lipoproteins.
CONCLUSIONS: The combination of isradipine plus enalapril reduced blood pressure
more effectively and was better tolerated than other drug alone. All three groups
showed similar changes in echocardiographic indices and no change in renal
function
High-performance liquid chromatographic evaluation of PCF 39, a new immunomodulator agent
No full textAccessing the Subsurface Biosphere Within Rocks Undergoing Active Low‐Temperature Serpentinization in the Samail Ophiolite (Oman Drilling Project)
No full textThe Oman Drilling Project established an “Active Alteration” multi-borehole observatory in peridotites undergoing low-temperature serpentinization in the Samail Ophiolite. The highly serpentinized rocks are in contact with strongly reducing fluids. Distinct hydrological regimes, governed by differences in rock porosity and fracture density, give rise to steep redox (Eh +200 to −750 mV) and pH (pH range 8.5–11.2) gradients within the 300–400 m deep boreholes. The serpentinites and fluids host an active subsurface ecosystem. Microbial cell abundances in serpentinite vary at least six orders of magnitude, from ≤3.5 × 101 to 2.9 × 107 cells/g. Low levels of biological sulfate reduction (2–1,000 fmol/cm3/day) can be detected in rock cores, particularly in rocks in contact with reduced groundwaters with pH \u3c 10.5. Thermodesulfovibrio is the predominant sulfate reducer identified via metagenomic sequencing of adjacent groundwater communities. We infer that transport and reaction of microbially generated sulfide with the serpentine and brucite assemblages gives rise to optical darkening and sulfide overprinting, including the formation of tochilinite-vallerite group minerals, potentially serving as an indicator that this system is inhabited by microbial life. Olivine mesh-cores replaced with ferroan brucite and minor awaruite, abundant veins containing hydroandradite garnet and polyhedral serpentine, and late-stage carbonate veins are suggested as targets for future spatially resolved life-detection investigations. The high-quality whole-round core samples that have been preserved can be further probed to define how life distributes itself and functions within a system where chemical disequilibria are sustained by low-temperature water/rock interaction, and how biosignatures of in situ microbial activity are generated
