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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In the present study, we have examined the role of gonadotropins and prostaglandins in the preovulatory increase of ovarian collagenase activity in the rat. Whole ovaries of immature PMSG-primed rats (20 IU) were removed before and 8 h after the rats were treated with human (h) CG, Nembutal, and/or indomethacin. The ovaries were homogenized in a solution containing Triton X-100 (0.25%) and centrifuged. Collagenase was extracted by resuspending the pellets in buffer containing 100 mM CaCl2, heating to 60 C for 6 min, and centrifuging. The supernatants were treated with dithiothreitol (2 mM) and iodoacetamide (5 mM) to inactivate collagenase inhibitors. Collagenase activity was measured as the percent digestion of 3H-type I collagen/100 microliters aliquot of ovarian sample. At zero time (52 h after PMSG), ovarian collagenase activity was 4.2 +/- 1.2% digestion (mean +/- SEM, n = 3). In ovaries collected 8 h after the endogenous LH surge or 8 h after the administration of 10 IU hCG at time zero, collagenase activity rose to 19.6 +/- 2.1 (n = 6) and 22.5 +/- 1.7% digestion (n = 11), respectively. Indomethacin (1.5 mg/100 g BW) administered 30 min after hCG, produced no change in collagenase activity (24.8 +/- 2.5% digestion, n = 7) although the expected increase in ovarian prostaglandin E after hCG treatment was blocked. When the endogenous LH surge was blocked with Nembutal (3 mg/100 g BW), collagenase activity in 8-h ovaries was 6.8 +/- 1.1% digestion (n = 10). The Nembutal block of the preovulatory collagenase increase was overcome by administration of hCG (8-h ovarian enzyme activity = 22.7 +/- 3.2% digestion, n = 8). These observations demonstrate that hCG stimulates ovarian collagenase activity and that this stimulation is not dependent on prostaglandin synthesis.
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PMID:The preovulatory increase in ovarian collagenase activity in the rat is independent of prostaglandin production. 300 37

A hybrid material with interesting capsule forming properties has been prepared by gamma-initiated polymerization of hydroxyethyl methacrylate (HEMA) or other acrylic monomers in the presence of aqueous sodium alginate. For example, an aqueous solution of HEMA (1 wt%) and sodium alginate (1 wt%) was irradiated in a gamma-source at a dose of 0.15 MR, to produce a stable emulsion which coalesced in the form of a homogeneous precipitate when added to 0.1 M CaCl2. Polymerization of HEMA was presumed to be initiated by free radicals generated in the alginate by gamma-irradiation. The emulsion consisted largely of polyHEMA homopolymer stabilized by an alginate-polyacrylate graft (or block) copolymer of highly branched and ill-defined character, which acts as surfactant to prevent coagulation of the emulsion. Erythrocytes were encapsulated in such an emulsion by extrusion of cell/copolymer emulsion mixture into HEPES buffered CaCl2 (10 mM Ca). Cells appeared intact and functional after encapsulation. By SEM it appeared that the capsule wall consisted of microspheres of polyHEMA on the inner and outer surfaces held together by the alginate. Furthermore the capsule did not contain the internal meshwork, characteristic of calcium alginate homopolymer gels. Although much remains to be learned about these materials, the combination of the easy gelling characteristics of the alginate with the range of desirable properties (e.g. biocompatibility) afforded by the acrylic monomers may have a significant impact on the development of cell microencapsulation technology.
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PMID:Graft copolymer emulsions of sodium alginate with hydroxyalkyl methacrylates for microencapsulation. 342 43

45Calcium uptake was studied with aspirin-treated platelets that were gel-filtered through a column of Sepharose 2B equilibrated with divalent cation-free modified Tyrode's solution to remove readily exchangeable surface-associated calcium. These platelets aggregated almost immediately when exposed to ADP, fibrinogen and at least 30 microM CaCl2. At this calcium ion concentration, 10(8) platelets took up 36.6 +/- SEM 2.7 pmol of 45calcium within 1-2 min. The presence of ADP and fibrinogen did not affect the amount of calcium bound. Over 90% of this platelet-associated calcium was removed by EDTA in 5 min suggesting that it was surface-bound. Calcium uptake increased rapidly for 10 min, then more slowly for up to 2 h. At 60 min, maximal uptake was approached at CaCl2 concentrations between 250 and 300 microM when an average of 276 +/- SEM 18 pmol of calcium was associated with 10(8) platelets. Only 50-60% of this calcium could be removed by EDTA in 5 min, and about 70% in 20 min, suggesting that some of it had been internalized. Platelets from two patients with thrombasthenia that were unable to aggregate took up 50% less calcium than platelets from normal volunteers. Similarly, platelets that had been incubated with EDTA at 37 degrees C, pH 7.8 for 8 min lost the ability to aggregate despite recalcification and took up 40-60% less calcium than CaEDTA-treated controls. Platelets from a patient with the Bernard-Soulier syndrome aggregated and bound calcium normally. Thus the platelets' ability to take up calcium after removal of surface-associated calcium correlates with their ability to aggregate. Since thrombasthenic platelets and platelets rendered incapable of aggregating after prolonged calcium deprivation with EDTA do not bind fibrinogen, we postulate that some of the surface-associated calcium normally binds to the fibrinogen receptors.
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PMID:Decreased association of 45calcium with platelets unable to aggregate due to thrombasthenia or prolonged calcium deprivation. 677 78

Phosphorus retention as a result of chronic renal failure (CRF) induces secondary hyperparathyroidism (HPT II) while supplemented low-phosphorus low-protein diets (LPD) prevent it. The aim of this study was to assess in seven patients with advanced CRF and biological HPT II the effects of a LPD providing daily 5 to 7 mg/kg phosphorus, 0.4 g/kg protein, 300 mg calcium (Ca) and supplemented with amino acids, ketoacids, CaCO3 and vitamin D2, on the relationship between ionized Ca (iCa) and PTH concentrations. Hyper- and hypocalcemia were induced by CaCl2 and Na2-EDTA infusion. After three months of LPD, serum phosphorus decreased from 1.59 +/- 0.15 to 1.26 +/- 0.24 mmol/liter (mean +/- SEM, P < 0.02), basal PTH levels from 251 +/- 25 to 127 +/- 16 pg/ml (P < 0.03), while basal iCa and GFR did not vary. The sigmoidal PTH-calcium curve shifted downward with maximal PTH decreased from 482 +/- 86 to 319 +/- 60 pg/ml (P < 0.02) and minimal PTH from 35 +/- 4 to 21 +/- 4 pg/ml (P < 0.05). On the other hand, the slope of the % maximal PTH-iCa curve, which is an indicator of the sensitivity of the parathyroid cell to changes in iCa concentrations, did not vary significantly. The set point of Ca and calcitriol levels were not modified. These results demonstrate a direct inhibition of PTH secretion over a wide range of iCa concentration by LPD in patients with advanced CRF and mild HPT II over a three months period. This effect is independent of changes in plasma calcitriol levels.
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PMID:Phosphorus and protein restriction and parathyroid function in chronic renal failure. 785 97

Titanium and its alloys have demonstrated considerable success in various surgical procedures including orthopedic, dental, and cardiovascular surgery. However, particulate debris from corrosion and wear is present in a considerable quantity in tissue local to the implant. This study evaluated the effect of Ca, since it is present in both serum and bone, and H2O2, since it is produced through local inflammation, on the amount of titanium release. Four sets of Ti6Al4V plates and Ti6Al4V screws were used. Each set was designated to one of four solutions: RPMI (cell culture growth media), RPMI with CaCl2, RPMI with CaCO3, and RPMI with H2O2. A fretter was used to cause corrosion by creating micromotion between two screws and a two-hole plate of Ti6Al4V. After fretting for 72 h, weight loss of the plate and screws and the amount of Ti and vanadium (V) in solution was used to assess the amount of fretting corrosion which had occurred. Results of weight loss and Ti in solution indicated that the presence of H2O2 increased the amount of particulate debris produced in RPMI as compared with RPMI alone. The addition of CaCl2 to RPMI also increased both weight loss and Ti in solution compared with RPMI alone. The addition of CaCO2, however, did not give values significantly different from RPMI alone. Comparison of weight loss and Ti in solution indicated that the increase in fretting corrosion was not different between RPMI with CaCl2 and RPMI with H2O2. The particulate wear debris from the four solutions was black in color and the size of the particulate produced was compared using a Coulter Multisizer. The results indicated that particles produced in the four solutions were not different, with mean values between 1.324 and 1.100 microns, and they were similar in size to the particulate found in tissues surrounding failed total hip replacements. In order to better understand the role of Ca in the fretting corrosion of Ti6Al4V, energy dispersive x-ray analysis (EDXA) using SEM was used to determine elemental composition of one countersink surface of a plate which had been run four times in RPMI with CaCl2. The presence of Ca in the bulk was not significant (% composition < 0.5%). However, Ca was present in two surface particles which were examined at a magnification of 55,000, with a Ca% composition of 63.2% and 19.2%. While results from this study indicate that both soluble Ca(CaCl2) and H2O2 increase the fretting corrosion of Ti6Al4V, the insoluble form of Ca, which would be found in bone and hydroxyapatite, has no effect. These data indicate that it is important to specify the media used in corrosion, dissolution, and elution experiments.
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PMID:Effects of Ca and H2O2 added to RPMI on the fretting corrosion of Ti6Al4V. 895 41

The compound 2,3,5,6-Tetramethylpyrazine (TMP; Ligustrazine), a flavouring component and sweetness enhancer for beverages constitutes a commonly used food additive. Now we studied the effect of TMP on coronary artery dilation during ischemia: In our experiments we used isolated, Langendorff-perfused guinea pig hearts, arrested with K(+)-rich Normal Tyrode solution (in mM: NaCl 129.5, KCl 15, MgCl2 0.8, CaCl2 1.0, glucose 10), buffered with 10 mM HEPES to pH 7.4 at 37 degrees C, equilibrated with 100% O2. Ischemia was simulated by equimolar replacement of glucose by 2-deoxyglucose (DOG), an inhibitor of oxydative phosphorylation. We found that coronary perfusion pressure (CPP) decreased by 20 +/- 1.2 cm H2O (from initially 90 cm H2O; n = 6, +/- SEM) within 15 min from the onset of DOG. In the presence of 1 mM TMP the decrease in CPP was largely attenuated and CPP declined by 1.4 +/- 1.0 cm H2O (n = 6, +/- SEM; p < 0.01). In 2 out of the 6 TMP experiments even as light increase in CPP (< 2 cm H2O) could be seen. We conclude that TMP, a blocker of ATP-dependent K(+)-channels in pancreatic beta-cells and possibly in arterial smooth muscle cells, prevents coronary dilation in response to ischemia. The possible suppression of this vital mobilization of coronary reserve during ischemia in patients with coronary artery disease certainly merits further attention and may question the use of this compound as a food additive.
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PMID:First description of the effect of a non-sulfonylurea compound, tetramethylpyrazine, on coronary response to desoxyglucose-induced ischemia. 957 20

Two proteins of 17 and 24 kDa, respectively, which were immunologically related to bikunin, were purified from urine of healthy men, using in the last step a trypsin CNBr-sepharose affinity column. These proteins strongly inhibited calcium oxalate (CaOx) crystallization in two in vitro models. In the first model, the presence of 8 microg/ml protein in a medium containing 0.76 mM CaCl2 (with 45Ca) and 0.76 mM ammonium oxalate inhibited the crystallization process by 80%, as estimated by supernatant radioactivity after 60 min of incubation. A similar inhibition was observed in the second turbidimetric model, where the CaOx crystallization kinetics were followed for 10 min at 620 nm in a medium containing 4 mM CaCl2 and 0.5 mM Na2Ox. These proteins were used as standard protein for the development of an enzyme-linked immunosorbent assay (ELISA) in urine. Mean (+/-SEM) urinary bikunin concentration in 18 healthy subjects was 5.01 +/- 0.91 microg/ml. This was a concentration range of strong inhibitory activity in vitro. Bikunin values were nearly 50% lower (2.54 +/- 0.42 microg/ml, P=0.007) in 31 CaOx renal stone formers (having weddelite crystals in their first morning urine) than in the healthy volunteers. A correlation was found between urinary bikunin and alpha-1 microglobulin concentrations in the control group (y=0.73x + 1.09, r2=0.8) while no such correlation existed in the lithiasis group. In conclusion, bikunin exerts a strong inhibitory action of CaOx crystallization in vitro. Its involvement in urinary CaOx crystallization of stone formers is highly probable, based on the significant decrease in its urinary concentration in the majority of stone formers studied.
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PMID:Inhibitory effect of bikunin on calcium oxalate crystallization in vitro and urinary bikunin decrease in renal stone formers. 1009 56

The influence of different factors on the lysis of the red microalga, Rhodella reticulata, by Cytophaga sp. LR2 was studied. The pathogenic bacterial strain was more resistant than the alga to the physiological parameters studied, which assured long-term survival of bacteria in algal cultures. Cytophaga sp. LR2 infected R. reticulata at temperatures between 15 and 30 degrees C, in the illuminated as well as the non-illuminated cultures, at pH values between 5.0 and 9.0, and in the presence of NaCl and CaCl2 in the culture medium. SEM showed a different morphology of the bacteria in algal cultures from those of axenic cultures of Cytophaga. Observations of specific associations between algal and bacterial cells revealed that the role of the slime extrusions on the bacterial surface was attachment of Cytophaga to algal cells, and that their clumping leads to rapid lysis.
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PMID:Influence of physiological factors on the lysis effect of Cytophaga on the red microalga Rhodella reticulata. 1073 6

Sperm capacitation was examined in the endangered Eld's deer (Cervus eldi thamin). Sperm motility and viability (percentage of sperm cells with intact membranes) were assessed in vitro over time after attempting to induce capacitation in TALP alone and TALP supplemented with calcium (10 mM CaCl2), dibutyryl cAMP (1 mM dbcAMP), or fetal calf serum (20% FCS). Sperm aliquots were evaluated at 0, 3, 6, 9, and 12 h for motility, viability, and ability to acrosome react after exposure to calcium ionophore (A23187, CI; 10 microM) or lysophosphatidylcholine (LC; 100 microg/mL). Fresh sperm aliquots in TALP + 10 mM CaCl2 exposed to CI had fewer (P < 0.05) intact acrosomes than the TALP control (TALP alone) or dbcAMP and FCS treatments after 9 h. Mean (+/- SEM) percentage of intact acrosomes of spermatozoa incubated in medium with increased CaCl2 declined (P < 0.05) from 80.2 +/- 2.6% (0 h) to 49.7 +/- 7.3% after prolonged incubation (9 h). The proportion of capacitated fresh spermatozoa was not influenced by LC treatment. Capacitation was not induced (P > 0.05) by any of the presumptive sperm capacitators after freeze-thawing. Likewise, neither CI nor LC induced the acrosome reaction (AR) in these spermatozoa, suggesting that the freeze-thawing process may have caused membrane damage. Results revealed that the supplementation of medium with CaCl2 evokes capacitation in some spermatozoa. However, Eld's deer spermatozoa appear remarkably resistant to conventional stimulators of capacitation and the AR.
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PMID:Sperm capacitation in vitro in the eld's deer. 1151 20

The vasorelaxing activity of rotundifolone (ROT), a major constituent (63.5%) of the essential oil of Mentha x villosa, was tested in male Wistar rats (300-350 g). In isolated rat aortic rings, increasing ROT concentrations (0.3, 1, 10, 100, 300, and 500 microg/ml) inhibited the contractile effects of 1 microM phenylephrine and of 80 or 30 mM KCl (IC50 values, reported as means +/- SEM = 184 +/- 6, 185 +/- 3 and 188 +/- 19 microg/ml, N = 6, respectively). In aortic rings pre-contracted with 1 microM phenylephrine, the smooth muscle-relaxant activity of ROT was inhibited by removal of the vascular endothelium (IC50 value = 235 +/- 7 microg/ml, N = 6). Furthermore, ROT inhibited (pD2 = 6.04, N = 6) the CaCl2-induced contraction in depolarizing medium in a concentration-dependent manner. In Ca2+-free solution, ROT inhibited 1 microM phenylephrine-induced contraction in a concentration-dependent manner and did not modify the phasic contractile response evoked by caffeine (20 mM). In conclusion, in the present study we have shown that ROT produces an endothelium-independent vasorelaxing effect in the rat aorta. The results further indicated that in the rat aorta ROT is able to induce vasorelaxation, at least in part, by inhibiting both: a) voltage-dependent Ca2 channels, and b) intracellular Ca2+ release selectively due to inositol 1,4,5-triphosphate activation. Additional studies are required to elucidate the mechanisms underlying ROT-induced relaxation.
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PMID:Calcium antagonism and the vasorelaxation of the rat aorta induced by rotundifolone. 1555 95


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