Search PubMed⌕ Search

Biomedical subjects

E Jaworski

Publications and source records attributed to E Jaworski.

At least 19 recordsLinked to original sources
PubMed1997

Development of a dose-response bioassay for stanniocalcin in fish.

Stanniocalcin (STC) is a polypeptide hormone that was first discovered in fish and recently identified in mammals. In fish, STC is released into the bloodstream in classical endocrine fashion and has well established regulatory effects on calcium and phosphate homeostasis. However, there are no suitable dose-response bioassays for STC and consequently no methods for assigning units of potency to preparations of the hormone. All the available in vitro bioassays are too complex from a technical standpoint to readily accommodate the large number of samples required in dose-response bioassays. Most in vivo bioassays are hampered by the fact that fish have natural rhythms governing plasma STC levels which tend to make them variably sensitive to the injected hormone. In this report we have developed a new in vivo bioassay for STC using rainbow trout. The key feature of the bioassay involves suppressing plasma STC levels to the extent that fish are always receptive to injected hormone. This has been accomplished by phosphate-loading the animals, which lowers their plasma calcium levels, removes the stimulus for STC secretion and brings about a reduction in resting plasma hormone levels. The net effect is an animal that is always responsive to injected STC. With this bioassay we have been able to obtain sensitive and reproducible, dose-related effects of salmon STC on gill calcium transport.

Aging↗
PubMed1997

Human stanniocalcin inhibits renal phosphate excretion in the rat.

Stanniocalcin (STC) is a glycoprotein hormone first identified in bony fishes where it counteracts hypercalcemia by inhibiting gill calcium uptake and stimulating renal inorganic phosphate (Pi) reabsorption. Human STC (hSTC) has recently been cloned and sequenced and is highly homologous to the fish hormone at the amino acid level. The objective of this study was to examine the possible effects of hSTC on electrolyte homeostasis and renal function in the rat. Recombinant hSTC was expressed in bacteria and purified by metal-ion affinity chromatography and reverse-phase high performance liquid chromatography. Anesthetized animals were given bolus infusions of 1, 5, or 10 nmol hSTC per kilogram of body weight. Control animals received solvent alone. The most effective dosage was 5 nmol/kg, which caused significant reductions in both absolute and fractional phosphate excretion in comparison with control rats. The hSTC had no effect on the renal excretion of other ions, the glomerular filtration rate, renal blood flow, blood pressure, or plasma electrolytes (Na+, K+, Ca2+, Pi, Mg/+). The maximum effect of hSTC on phosphate excretion was observed 60-80 minutes postinjection. Lesser effects were obtained with higher and lower dosages of hormone. When renal cortical brush-border membrane vesicles were isolated from control and hormone-treated animals 80 minutes postinjection, the rate of Na+/Pi cotransport was found to be 40% higher in vesicles from hormone-treated animals (p < 0.01; 5 nmol hSTC/kg). Together, the renal clearance and membrane vesicle data indicate that hSTC participates in the renal regulation of Pi homeostasis in mammals.

Animals↗
PubMed1994

Calcium regulates stanniocalcin mRNA levels in primary cultured rainbow trout corpuscles of stannius.

Stanniocalcin (STC) is an inhibitor of gill calcium transport produced by the corpuscles of Stannius (CS), endocrine glands in bony fishes. In previous studies we have described how STC secretion is regulated by calcium both in vitro and in vivo, using rainbow trout as a model system. In this report we have examined the effects of calcium on STC mRNA levels in primary cultured trout CS cells. The results show that message levels are positively regulated by extracellular calcium concentrations within the physiological range. The calcium response was also temporally-related as more prolonged exposures tended to have greater effects. Similar concentrations of magnesium had no effect on message levels. This represents another level at which calcium regulates the CS cell, in addition to its established effects on STC synthesis and secretion. The results are discussed in relation to the other known calciotropic hormones, calcitonin and parathyroid hormone.

Animals↗
PubMed1993

Evidence for two intracellular calcium pools in Dictyostelium: the cAMP-induced calcium influx is directed into a NBD-Cl- and 2,5-di-(tert-butyl)1,4-hydroquinone-sensitive pool.

Signal transduction in Dictyostelium for oriented movement and differentiation involves a fine tuning of the cytosolic Ca2+ concentration. We have previously shown that cAMP binding to the cell surface receptor elicits two cellular events: (i) to enhance Ca2+ entry across the plasma membrane; (ii) to increase Ca2+ uptake into Ca(2+)-sequestering organelles. Here we used permeabilised cells to show that cAMP-induced Ca2+ uptake in these cells was sensitive to the Ca2+ transport ATPase blocker 2,5-di-(tert-butyl)-1,4-hydroquinone (BHQ) and the vacuolar H(+)-ATPase inhibitor NBD-Cl. By contrast, bafilomycin A1 and vanadate, inhibitors of Ca2+ uptake into acidosomes in Dictyostelium, did not reduce the cAMP-induced Ca2+ uptake of permeabilised cells. GTP gamma S served as a tool to measure Ins(1,4,5)P3- (InsP3)-sensitive Ca2+ release. Following NBD-Cl or BHQ treatment Ca2+ release was reversibly inhibited. We conclude that the cAMP-controlled Ca2+ influx is directed into a NBD-Cl and BHQ-sensitive compartment, which comprises the InsP3-releasable pool. The acidosomal Ca2+ store seems to provide for additional Ca2+ if required.

4-Chloro-7-nitrobenzofurazan↗
PubMed1992

[Elaboration and examination of the functioning of a new system for collection and analysis of information on foodborne and waterborne diseases in Poland].

During 1986-1989 the new computerized system of collection and analysis of foodborne and waterborne infections and intoxications (based on the proposition of World Health Organization) was developed in the Department of Epidemiology of the National Institute of Hygiene in Warsaw. System consists of the new forms (including computer's form) and adapted original programming. The new forms were officially introduced by the Ministry of Health and Welfare for the use by the all Sanitary Stations in Poland from the beginning of 1991. That system was served to present data on epidemiological situation of foodborne and waterborne infections and intoxications in Poland in 1988-1991, demonstrated in the paper. Criteria of analysis were adapted to meet conditions of the international cooperation, and-first of all-to the requirements of Polish epidemiological situation.

Data Collection↗
PubMed1991

Mutant analysis suggests that cyclic GMP mediates the cyclic AMP-induced Ca2+ uptake in Dictyostelium.

Previous work has shown that streamer F (stmF) mutants of Dictyostelium discoideum exhibit prolonged chemotactic elongation in aggregation fields. The mutants carry an altered structural gene for cyclic GMP phosphodiesterase resulting in low activities of this enzyme. Chemotactic stimulation by cyclic AMP causes a rapid transient increase in the cyclic GMP concentration followed by association of myosin heavy chains with the cytoskeleton. Both events persist several times longer in stmF mutants than in the parental strain, indicating that the change in association of myosin with the cytoskeleton is transmitted directly or indirectly by cyclic GMP. We measured the cyclic AMP-induced Ca2+ uptake with a Ca(2+)-sensitive electrode and found that Ca2+ uptake was prolonged in stmF mutants but not in the parental strain. The G alpha 2 mutant strain HC33 (fgdA), devoid of InsP3 release and receptor/guanylate cyclase coupling, lacked Ca2+ uptake. However, the latter response and cyclic GMP formation were normal in the signal-relay mutant strain agip 53 where cyclic AMP-stimulated cyclic AMP synthesis is absent. LiCl, which inhibits InsP3 formation in Dictyostelium, blocked Ca2+ uptake in a dose-dependent manner. The data indicate that the receptor-mediated Ca2+ uptake depends on the InsP3 pathway and is regulated by cyclic GMP. The rate of Ca2+ uptake was correlated in time with the association of myosin with the cytoskeleton, suggesting that Ca2+ uptake is involved in the motility response of the cells.

Animals↗
PubMed1985

Afferent innervation of extraocular muscles in the rat studied by retrograde and anterograde horseradish peroxidase transport.

After injection of horseradish peroxidase (HRP) into extraocular muscles of rat perikarya were labeled mainly along the medial edge of the ophthalmic subdivision of the trigeminal ganglion but not in the mesencephalic nucleus of the trigeminal nerve. Injections of HRP into the trigeminal ganglion labeled simple as well as branching and meandering free fiber endings in extraocular muscles. No evidence for muscle spindles was found, but the meandering endings may be considered as candidates for stretch receptors.

Animals↗