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J Espinosa

Publications and source records attributed to J Espinosa.

At least 55 records · Page 3Linked to original sources
PubMed1990

Glucose release in mantle tissue of Mytilus: regulation by calcium ions.

Glucose release activity in mantle tissue of Mytilus galloprovincialis was studied. Mantle tissue shows a basal glucose releasing activity. The external Ca2+ absence increases 2 to 3-fold the basal glucose release, and when A23187 (10 microM) was simultaneously present the release doubled that obtained in Ca2(+)-absence. EGTA (2 mM), chlorpromazine (200 microM) and lanthanum (3 mM) decreased the glucose release promoted by external Ca2+ absence. This and other data suggest that glucose release activity in mantle tissue might be controlled by Ca2+ ions.

Animals↗
PubMed1990

Occupational risk factors for cancer of the larynx in Spain.

Spain is one of the countries with the highest incidence of laryngeal cancer and, together with France, is the country with the lowest percentage of women with this disease. In order to identify the occupational risk factors associated with laryngeal cancer in this country a case-control study was performed. Cases included 85 patients with epidermoid carcinoma of the larynx diagnosed in "La Paz" Hospital, Madrid, between 1985 and 1987. A sample of 170 patients from the same hospital was used as control. The results of the study revealed that 56.5% of larynx cancer patients had a sedentary occupation working in the service sector. Exposure to insecticides or silica were strongest risk factors for laryngeal cancer. An association between laryngeal cancer and exposure to fumes, chemical products, mineral dust, or wood dust was not found.

Adult↗
PubMed1989

[Zonal variability and seasonal changes of the content of glycogen and glucose in the Mytilus mantle].

Glycogen and free-glucose content in the ventral, central and dorsal parts, as well as glucose-6-phosphate phosphatase activity in mantle of Mytilus galloprovincialis Lmk. were examined. The glycogen content of mantle did not manifest asymmetrical distribution among the three parts. In the period studied, the typical glycogen content profile variation was found, being maximum in July. The tissue free-glucose content was similar in each part, and the obtained seasonal variation profile was opposite to the glycogen content, reaching the minimum in July. For every part of mantle, free-glucose/glycogen ratio showed similar monthly profiles. In each part the 50% point was found in July. Glucose-6-phosphate phosphatase activity was not found in the mantle tissue.

Animals↗
PubMed1988

Mutagenicity of products generated by the reaction between several antiparasitic drugs and nitrite.

Drugs containing secondary aliphatic amines, heterocyclic nitrogen, or secondary aliphatic amido groups (chloroquine, dehydroemetine, mebendazole, and piperazine) and pyrimidine derivatives such as pyrantel pamoate were reacted in vitro with sodium nitrite at pH 3.7 and became mutagenic for Salmonella typhimurium strain TA1535. The products derived from the nitrosation of chloroquine and dehydroemetine required metabolic activation by mammalian hepatic S9 to be mutagenic. The N-nitroso derivatives of mebendazole, piperazine, and pyrantel pamoate were mutagenic with and without S9, although more activity was noted in the presence of S9 with the nitrosated compounds formed from mebendazole and piperazine. Under identical conditions, no mutagenic products were detected from quaternary ammonium salts such as bephenium hydroxynaphthoate or drugs containing tertiary heterocyclic amino groups, such as iodochlorhydroxyquin.

Amebicides↗
PubMed1988

Dual effect of dihydropyridines on 45Ca uptake induced by the K+ -channel blocker, 4-aminopyridin on mast cells.

The 1,4-dihydropyridines (DHP) are calcium antagonists and represent a new class of drugs which act by a selective inhibition of Ca++ influx through voltage-operated calcium channels. We report the effect of nifedipine (Bay A 1040), nisoldipine (Bay K 5552) and nitrendipine (Bay E 5009) on the histamine release and on the 45Ca uptake promoted by 4-aminopyridin in mast cells. These cells treated with DHP (10(-12)-10(-3) M) activated the secretory response in a dose-dependent manner in the range of concentrations 10(-6)-10(-3) M, whereas concentrations of 10(-12)-10(-6) M did not significantly inhibit the secretion. 4-Aminopyridin, a known K+ -channel blocker, induced 45Ca uptake. Pretreatment of mast cells with DHP prior to 4-aminopyridin stimulation inhibited or stimulated 45Ca uptake depending on concentration; thus, concentrations of DHP below 10(-12) of nitrendipine and 10(-9) for nisoldipine and nifedipine were inhibitory, while higher doses potentiated 45Ca uptake. These results demonstrate a diversity of pharmacological effects of DHP on mediator secretion and 45Ca uptake in mast cells and throw into question their only properties as Ca++ antagonists.

4-Aminopyridine↗
PubMed1988

Sperm shape abnormality and urine mutagenicity in mice treated with niclosamide.

Niclosamide, a widely used anthelmintic drug in underdeveloped countries, is known to be mutagenic in the Salmonella typhimurium microsomal test system. The urine obtained from mice treated with niclosamide is mutagenic in the TA98 and TA1538 strains. Its effects on mouse-sperm morphology were evaluated in CD1 and (BALB/cJ x DBA/2J) F1 mice after 5 daily oral niclosamide doses of either 60, 80, 100 or 120 mg/kg. A statistically significant increase in abnormal sperm morphology was detected in both CD1 and (BALB/cJ x DBA/2J) F1 mice. No drug-related effects on testis weight nor on sperm count were observed in either genotype. Urine samples obtained from niclosamide-treated F1 mice were assayed with the Salmonella typhimurium strain TA1538 both in the absence and presence of beta-glucuronidase. In the absence of glucuronidase, urine mutagenicity increased with increasing dose and the highest doses were toxic. In the presence of glucuronidase, urine mutagenicity and toxicity also increased. Only at the highest dose (120 mg/kg), however, was there a positive correlation between the urine mutagenic activity and an increase in the number of abnormal sperm. The results of this study suggest that the increase in abnormal sperm depends on the systemic presence of non-conjugated niclosamide metabolites.

Animals↗
PubMed1988

[Effect of colchicine on histamine secretion and calcium uptake in mast cells].

The function of contractile system of microtubules on the mechanism of mast cell exocytosis by using colchicine, a depolymerizing alkaloid of the microtubular system, has been studied. The response of histamine release and 45Ca-uptake in isolated rat mast cells treated with colchicine has been determined. The incubation of mast cells in the presence of 10(-8)-10(-3) M colchicine slightly inhibits histamine secretion induced by the stimulant concentration 50 micrograms/ml of compound 48/80 (35 +/- 5%). Similarly colchicine does not significantly affect histamine values spontaneously elicited in unstimulated mast cells; the percentages of secretion are never greater than 10%. However, high doses of this alkaloid are found to markedly inhibit entry of calcium ions into the cell. These results suggest that microtubules do not participate in the secretory process of mast cells, although they significantly decrease calcium uptake. The microtubules might be connected to the membrane, so that the depolymerization of this contractile system could damage the membrane structures through which Ca2+ is transported.

Animals↗
PubMed1987

Valinomycin, a degranulating agent in rat mast cells which inhibits calcium-uptake.

The effect of valinomycin on both, mast cell histamine release and on calcium (45Ca)-uptake processes was examined. Pleural and peritoneal mast cells were purified in isotonic Percoll (pH = 7) and mixed populations were used in the experiments. Valinomycin (10(-9)-10(-5) M) stimulated histamine release in isolated rat mast cells when the incubation medium contained high K+ concentrations (Tris-K+ with 150 mM K+), but not in other media such as Tris-Na+ (120 mM Na+) or Tris-sucrose (300 mM sucrose). In contrast, in the absence of valinomycin, elevated K+ levels in the external environment did not activate mast cell secretion. Optimum response in valinomycin-treated mast cells was obtained when the cells were incubated for 60 min. Also valinomycin (10(-5) M) induced substantial inhibition of 45Ca-uptake while lower doses (10(-9)-10(-7) M) did not affect or only slightly increased uptake. In this paper valinomycin is shown to be a degranulating agent eliciting mediator release in mast cells incubated in the presence of high K+ levels, which does not require extracellular calcium and inhibits 45Ca uptake. The possibility that valinomycin acts as a K+ ionophore, as in other secretory systems, is discussed.

Animals↗
PubMed1987

Adrenergic activity on rat pleural and peritoneal mast cells. Loss of beta-receptors during the purification procedure.

Adrenergic agonists inhibit the release of histamine from rat pleural and peritoneal mast cells stimulated with compound 48/80 to a degree dependent on their beta-activity. Isoprenaline takes part in a stereoselective inhibitory action in the range 10(-7)-10(-4) M. Adrenaline induces a similar response pattern, with inhibition at higher concentrations. The response profile, but not the maximum values of inhibition, is clearly dependent on the concentration of the histamine releaser. Noradrenaline by itself is a histamine releaser, no stereoselectivity being observed. In the presence of compound 48/80 it takes part in a non-stereoselective inhibitory reaction at low concentrations. Inhibition of histamine release by isoprenaline was antagonized by 10 or 100 microM propranolol except at the highest isoprenaline concentration (1 mM). Both atenolol and propranolol nullified the inhibitory activity of noradrenaline, but not the increased histamine release it induces at higher concentrations (at least when acting in conjunction with compound 48/80). When rat mast cells are purified through Percoll, a change in their response profiles is observed. Isoprenaline and adrenaline by themselves elicit non-specific release of histamine; with compound 48/80, release is additive in the case of isoprenaline and supra-additive in the case of adrenaline. Results point to the loss of beta-adrenergic inhibitory activity after purification.

Animals↗
PubMed1987

Hydralazine-relaxing effect on rat aorta is not mediated through changes in ATPase activity.

Hydralazine, a hypotensive agent, induces relaxation on smooth musculature. Several mechanisms related to membrane processes have been proposed to explain its relaxing action. In the present paper, the effects of hydralazine on ATPase activity in rat aorta have been studied. Hydralazine (10(-4)-5 X 10(-3) M concentration-dependently relaxed the isolated rat aortic arterial strips under norepinephrine-, serotonin- and K+-contractures. 5-Hydroxytryptamine contractures were more sensitive to the effects of hydralazine than noradrenaline- and potassium-contractures. We found that hydralazine does not modify ATPase activity on rat aorta homogenates. On the other hand, ATPase activity of rat aorta homogenates is dependent on divalent cations Ca2+ and Mg2+, and a little Na, K-ATPase activity was found.

Adenosine Triphosphatases↗
PubMed1987

[Ring chromosome 18 46,XY,r(18)].

Authors report a ring chromosome 18 (18 r) in a four year old boy, with low birth weight, retarded growth and development, microcephaly and plagiocephaly, horizontal nystagmus, ambiguous genitalia, clinodactyly of the fifth finger, distal axial triradius, whorls pattern in 8 fingers in dermatoglyphic. Serum IgA is lower than 3 mg/dl. Parents karyotype is normal.

Child, Preschool↗
PubMed1986

In vivo inhibition of polymyxin B-induced hypotension: evidence of beta-adrenergic inhibitory activity on rat mast cells.

In vitro, rat mast cells show a dose-inhibition profile when stimulated with compound 48/80 in the presence of isoprenaline. Isoprenaline-induced inhibition is stereoselective at low concentrations, being greater on pleural mast cells. In vitro, polymyxin B (0.02-0.05 mg/kg) induces a marked hypotension and slow heart rate, but not tachyphylaxis. Both effects were not suppressed in the presence of isoprenaline (with short half-life in vivo), but orciprenaline does induce a clear inhibition of Polymyxin B-induced hypotension, which correlates well with heart rate.

Animals↗
PubMed1986

Staining of Merkel cells of pig snout epidermis using the uranaffin reaction. Morphometric analysis of neuroendocrine granules.

The uranaffin reaction (UR) specifically stains neurosecretory (NS) granules of the neuroendocrine system when performed at pH 3.9 and at a 4% concentration of uranyl acetate. Merkel-cell NS granules stained using the UR were found to have a different appearance than granules observed after routine processing. We therefore compared the average values obtained with both methods, examining the maximum diameter, area, form factor, and numerical density of such NS granules. The maximum diameter and area of NS granules were significantly greater (P less than 0.001) in samples stained using a conventional technique (CT) (93.30 nm, 6,411 nm2) that in those stained with the UR (63.95 nm, 2,148 nm2). The form factor of conventionally stained NS granules (0.9) was significantly greater (P less than 0.001) than that of granules stained with the UR (0.7). No significant difference in numerical density was found for the two techniques (CT: 8.11 +/- 2.51; UR: 6.14 +/- 2.38). It was found that the UR is a useful cytochemical marker for NS granules of Merkel cells, and that the ultrastructural morphology and intracellular arrangement of NS granules stained with the UR are different from those revealed using CT.

Animals↗
PubMed1986

[Response of pleural and peritoneal mastocyte populations in the rat to agents with different mechanisms of action].

Histamine release from rat pleural and peritoneal mast cells not previously purified is presented. Cells are stimulated by different mechanism-acting pharmacologic agents. FNa, theophylline, ruthenium red, chlorpromazine and propranolol are used. Results show that both cell populations are pharmacologically different, with distinct responses in the presence of FNa or chlorpromazine. Chlorpromazine and propranolol are cytolytic agents.

Animals↗
PubMed1986

Effect of calcium on histamine release from pleural and peritoneal mast cells induced by catechol.

Histamine release from rat pleural and peritoneal mast cells induced by catechol (1, 10, 50, 250 microM and 1 mM) has been studied. The dose-response induced by catechol is non-cytotoxic, is not modified by purification of mast cells and is calcium independent. The sensitivity and maximum response to catechol is the same irrespective of the presence or absence of Ca++, except on purified pleural mast cells, that showed a plateau response at 250 microM catechol in the absence of Ca++, and on unpurified peritoneal mast cells which exhibited a lower maximum response equally in the absence of Ca++. The release is induced by catechol at concentrations as low as 50 microM in all cases, and the maximum response is reached at 1 mM.

Animals↗
PubMed1986

[Na+ K+ ATPase activity in mast cells from the pleural and peritoneal cavities of the rat].

ATPase activity in rat mast cells was studied, assuming that pleural and peritoneal mast cells are different populations. Mast cells were purified with Percoll. Enzymatic activity was found to be 36% higher in pleural cells that in peritoneal cells. Moreover, for both populations results show a Na+-K+ ATPase activity either low or slightly inhibited by ouabain.

Animals↗