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Biomedical subjects

M Gonzalez

Publications and source records attributed to M Gonzalez.

At least 19 recordsLinked to original sources
PubMed1992

Effects of Na+ transport inhibitors on guinea-pig tracheal responses to spasmogens.

The effects of ouabain, amiloride, K(+)-free solution and low Na+ (25 mM) solution on the responses to CaCl2 (in Ca(2+)-free, K(+)-depolarizing solution), KCl, acetylcholine, histamine and 5-hydroxytryptamine were studied in guinea-pig isolated trachea. Ouabain (10 microM) did not alter the contractile responses to CaCl2, KCl and acetylcholine but depressed those to histamine and 5-hydroxytryptamine produced in normal Ca2+ (2.5 mM) and Ca(2+)-free (EGTA 0.1 mM) media. Amiloride (0.1 mM), K(+)-free solution, and low Na+ solution depressed responses to acetylcholine, histamine and 5-hydroxytryptamine produced in normal Ca2+ and Ca(2+)-free media. Ouabain and amiloride had no effect on responses of skinned strips to Ca2+. The mechanism of the inhibitory effects of these interventions is uncertain but the findings suggest that the availability of Na+ influences the airway smooth muscle responses to spasmogens.

Acetylcholine↗
PubMed1992

Increased expression of natural-killer-associated and activation antigens in multiple myeloma.

The expression of both natural-killer (NK)-associated and activation antigens was studied by flow cytometry in the peripheral blood of 47 untreated multiple myeloma (MM) patients. A significant increase in both absolute and relative numbers of CD57 positive cells as well as in the proportion of CD16 and CD11b cells was observed in patients with MM, specially in those in early stages of the disease (clinical stages I and II), suggesting a possible surveillance mechanism in response to an emerging malignant clone. Additional double stainings showed that strong CD16+ NK cells coexpress the CD56, CD11b, and CD2 antigens, while they lacked CD3, CD5, and WT31 antigens. Moreover, the previously reported increase in CD8 cells present in MM would be mainly due to a subset of CD8 cells that coexpress the CD57 Ags. The expression of activation antigens, especially CD38, was increased in peripheral blood lymphocytes of MM patients, the differences reaching statistical significance both in absolute and relative numbers in those cases with high numbers of CD16 NK cells and thus suggesting that these cells are functionally activated. These results reveal the existence of an increase in NK and activated cells in the peripheral blood of myeloma patients that may reflect a host's immunological mechanism in an attempt to modulate tumor cell growth.

ADP-ribosyl Cyclase↗
PubMed1992

Effects of low temperature and pharmacological interventions on the responses of the isolated guinea-pig trachea.

Cooling the guinea-pig isolated trachea from 37 degrees C to 20 degrees C virtually abolished the response to CaCl2 (in K(+)-depolarized tissues) and depressed that to histamine (about 75% reduction), KCl and 5-hydroxytryptamine (around 50% inhibition) while the response to acetylcholine remained unaffected. A further cooling to 10 degrees C was necessary to inhibit acetylcholine-induced contractions. Hyporesponsiveness to spasmogens by cooling was not associated with subsensitivity (increased EC50) except for 5-hydroxytryptamine. Contractile responses to KCl (50 mmol/l), histamine (1 mmol/l) and 5-hydroxytryptamine (0.1 mmol/l) in a Ca(2+)-free EGTA (0.1 mmol/l)-containing solution were inhibited by cooling to 20 degrees C but responses to acetylcholine (1 mmol/l) in the same experimental conditions were not affected. Cooling to 20 degrees C after treatment with an antagonist (ouabain 10 mumol/l, amiloride 0.1 mmol/l or vanadate 0.1 mmol/l) or after incubation in K(+)-free medium or low Na+ (25 mmol/l) solution produced the same or greater inhibitions of tracheal responses to spasmogens than cooling alone. The guinea-pig trachea treated with phorbol 12,13-diacetate (PDA; 1 mumol/l) and cooled to 20 degrees C responded to spasmogens similarly to a trachea untreated with PDA at 37 degrees C. In contrast, PDA (1 mumol/l) did not counteract the depressed responsiveness to histamine of ouabain (10 mumol/l)- or amiloride (0.1 mmol/l)- treated tracheal strips at 37 degrees C. PDA (1 mumol/l) enhanced tracheal contractions caused by KCl (50 mmol/l) in Ca(2+)-free medium at 20 degrees C but failed to augment those to histamine in the same conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Amiloride↗
PubMed1992

Initial experience with low-potassium cold blood cardioplegia: a clinical comparative study.

This study presents the results of bypass grafting in 96 patients operated on for triple-vessel coronary artery disease between May 1988 and September 1990. In the first 54 patients a cold crystalloid solution was employed, and in the 42 more recent patients cold blood low-potassium cardioplegia was employed. There were no differences in postoperative cardiac index or left ventricular stroke work index. Yet, in patients with impaired prebypass left ventricular stroke work index, postbypass left ventricular performance correlated negatively with duration of aortic cross-clamping in the cold crystalloid group (r = -0.441, p = 0.045). In contrast, no correlation was found in the cold blood low-potassium group (r = 0.125, p = 0.587). The incidence of myocardial infarction, need for inotropic support, and need for intraaortic balloon counterpulsation were similar among the groups. Release of the myocardial isoenzyme creatine kinase-MB from 12 to 30 hours after operation was significantly less in the low-potassium blood cardioplegia group. The use of low-potassium blood cardioplegia resulted in a marked reduction in the operative administration of fluids (1,527 +/- 87 versus 3,511 +/- 148 mL; p less than 0.001). In conclusion, low-potassium cold blood cardioplegia is a simple and effective method of myocardial protection. The fact that left ventricular stroke work index recovery was not dependent on the duration of aortic occlusion and that release of the MB isoenzyme of creatine kinase was reduced in the low-potassium blood cardioplegia group implies better myocardial protection.

Adult↗
PubMed1992

Effects of disulfiram, phenoxybenzamine and propranolol on the behaviors evoked by apomorphine and amphetamine in adult cats.

The aim of this work was to study the role that the noradrenergic system could play in the mechanism of production of the behaviors evoked by parenteral injection of apomorphine and amphetamine in adult cats. Ten cats were injected s.c. with 2 mg/kg of apomorphine and 2.5 mg/kg of amphetamine in separate sessions. The behaviors were recorded, until control conditions were again attained. In a second stage, disulfiram was administered ip., followed by apomorphine and amphetamine in the same doses as cited above. The effects on behaviors produced by disulfiram and those of apomorphine and amphetamine were recorded by three independent observers. Comparisons of the pre- and post-disulfiram behavioral results were analyzed with the help of the non-parametric Wilcoxon signed rank test. In another group of ten cats a similar procedure was carried on employing the alpha and beta noradrenergic blocking agents, phenoxybenzamine and propranolol. The noradrenergic blocking drugs, especially disulfiram and phenoxybenzamine produced by themselves a decrease in motility, in alertness and an increase in indifference and inappetence. Apomorphine and amphetamine administered after the blocking drugs showed slight behavioural modifications, reflection most of them the changes produced by the three blocking drugs. It is concluded that probably the nor-adrenergic system could be involved in the hypomotility elicited by amphetamine. NA is not involved in the induction of the other behaviors evoked by apomorphine and amphetamine.

Amphetamine↗
PubMed1992

Isolation of proteoglycans synthesized by rat heart: evidence for the presence of several distinct forms.

1. The proteoglycans (Ps) synthesized by auricle and ventricle from adult rat heart were studied. 2. Auricle tissue incorporated over two times radioactive sulfate compared to ventricle tissue and the Ps were mainly found in the detergent insoluble fraction. 3. The Ps from both tissues were isolated by ion-exchange chromatography on DEAE-Sephacel, followed by gel filtration on Sepharose CL-6B and SDS-PAGE electrophoresis. 4. Enzymatic and chemical degradation of these Ps suggest that at least three and probably four different species of Ps can be observed in heart tissue. 4. A high molecular weight chondroitin sulfate-P, a high molecular weight heparan sulfate-P, a chondroitin/dermatan sulfate-P of 240-200 kDa and a dermatan sulfate of 115 kDa. 5. This latter P was specifically immunoprecipitated using rat decorin antiserum.

Animals↗
PubMed1992

Hypoglycemic activity of olive leaf.

The hypoglycemic activity of olive leaf was studied. Maximum hypoglycemic activity was obtained from samples collected in the winter months, especially in February. One of the compounds responsible for this activity was oleuropeoside, which showed activity at a dose of 16 mg/kg. This compound also demonstrated antidiabetic activity in animals with alloxan-induced diabetes. The hypoglycemic activity of this compound may result from two mechanisms: (a) potentiation of glucose-induced insulin release, and (b) increased peripheral uptake of glucose.

Animals↗
PubMed1992

Does flow character of cardiopulmonary bypass make a difference?

The influence of pulsatile bypass flow on the performance of the cardiovascular system, fluids and blood balance, acid-base equilibrium, and splanchnic function was investigated. One hundred patients scheduled for elective coronary artery bypass grafting were randomly divided into a group of standard perfusion (NP) and a group of pulsatile perfusion (PP). At the end of the operation, similar cardiac performance developed in both groups that was higher than before bypass: left ventricular stroke work index after bypass, 56.8 +/- 2.7 gm/beat per square meter in the NP group and 56.7 +/- 2.6 gm/beat per square meter in the PP group (not significant). Further determinations did not differ among the groups. After discontinuation of cardiopulmonary bypass, bypass grafts flow measured using an electromagnetic probe did not differ among the groups. During the postbypass period, mean arterial pressure and systemic vascular resistance were similar (mean arterial pressure 86.8 +/- 1.6 mm Hg in the NP group and 88.5 +/- 1.7 in the PP group; systemic vascular resistance 817 +/- 33 dyne.sec/cm5 in the NP group and 881 +/- 34.5 in the PP group), as were further determinations. However, severe hypotension requiring the administration of vasoconstrictors was observed more frequently in PP group of patients (20 versus 6%; p < 0.05). Fluid balance determined at the second postoperative day was similar among the groups (+1307 +/- 239 ml in the NP group and +1535 +/- 266 ml in the PP group). Blood loss was 1122 +/- 120 ml in the NP group and 1263 +/- 119 ml in the PP group during the first postoperative day (p = 0.407). Urine output during bypass was lower in the PP group (261 +/- 25 versus 341 +/- 26 ml/hr; p = 0.028). The creatinine clearance was 96.4 +/- 10.3 ml/min in the NP group and 92.6 +/- 7.0 ml/min in the PP group (not significant); amylase and lipase clearance did not differ among the groups. Finally, no significant difference was detected in arterial lactic acid determinations and acid-base balance assessment between the groups postoperatively. Thus equivalent cardiovascular hemodynamics, a good control of fluids and blood balance, acid-base equilibrium, and a satisfactory protection of the function of kidneys and pancreas were obtained with both types of perfusion.

Cardiopulmonary Bypass↗
PubMed1991

Purification and properties of membrane and cytosolic phosphatidylinositol-specific phospholipases C from human spleen.

Two phosphatidylinositol-specific phospholipases C (PI-PLC) have been purified from human spleen. PI-PLCm represents the main activity detected in the membrane, while PI-PLCc is the main activity present in the cytoplasm. PI-PLCm can be resolved into two peaks of activity of high Mr (60,000-70,000) and low Mr (16,000-18,000). High salt concentration ((NH4)2SO4, 2M) dissociates the high Mr form yielding the low molecular form and increasing the specific activity. The same effect of dissociation and potentiation of the activity is observed when membranes solubilized by n-octyl glucoside are subjected to the high voltage conditions of an isoelectric focusing run. The purified Pi-PLCm has a Mr of about 18,000 when analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis or gel filtration and a basic pI (9.0-9.2). Purified PI-PLCc has a Mr of 57,000 (sodium dodecyl sulfate-polyacrylamide gel electrophoresis or gel filtration) and a slightly acid pI (6.2). Other characteristics of both enzymes, such as cations dependence, substrate specificity, optimum pH, and kinetic parameters, are also discussed.

Chromatography, Liquid↗
PubMed1991

Description of an enzyme-linked immunosorbent assay for the detection of protein tyrosine kinase.

A solid immunoassay for the detection of protein tyrosine kinases has been developed. It is based on the binding of the synthetic polypeptide poly(Glu.Na,Tyr) 4:1 to microELISA wells, where the phosphorylation reaction takes place in the presence of ATP and enzyme. The phosphorylated tyrosine residues produced in the reaction are finally detected, in the same well, by means of an ELISA using monoclonal antiphosphotyrosine antibody, peroxidase-labeled goat anti-mouse IgG antibody, and substrate. The amount of protein tyrosine kinase activity present in the sample is proportional to the color at 492 nm developed in each well.

Adenosine Triphosphate↗
PubMed1991

Antibodies to hepatitis C virus in low-risk blood donors: implications for counseling positive donors.

The significance of antibodies to hepatitis C virus (HCV) found by screening enzyme-linked immunoassay testing in a low-risk blood donor population is unclear. The rate of false positivity in this group as well as the usefulness of supplemental testing were examined by correlating the results of two screening enzyme-linked immunoassays (Ortho Diagnostics, Raritan, NJ, and Abbott Laboratories, North Chicago, IL) with supplemental antibody testing by the recombinant immunoblot assays (1 and 2) (Ortho) and neutralization assay (Abbott). Polymerase chain reaction was used to detect HCV genomic RNA to confirm viremia. Among 11.243 volunteer donors who were screened for the presence of antibodies to HCV by enzyme-linked immunoassay, 60 (0.53%) sera were repeatedly reactive. Twenty-five of these 60 sera were available for further testing. Seven sera were reactive by both screening enzyme-linked immunoassays, as well as by both recombinant immunoblot and neutralization assays. Six of these seven sera had detectable HCV genomic RNA by polymerase chain reaction. Among the remaining 18 sera, none were reactive by either recombinant immunoblot assays, whereas two sera were reactive by the neutralization assay only. None of the 18 samples had detectable HCV genomic RNA. Five of the six sera with elevated aminotransferase levels were among the seven sera reactive by all immunoassays. It is concluded that there is a significant false positivity rate associated with screening enzyme-linked immunoassay testing in a low-risk blood donor population. Supplemental testing correlates well with detection of hepatitis C genomic material by polymerase chain reaction and identifies donors who are truly infected.

Base Sequence↗
PubMed1991

Effects of central and peripheral inputs on single pineal cell activity in the rat.

The influences exerted by central and peripheral afferents to the pineal gland have been studied in rats anesthetized with urethane (1.2 g/kg, i.p.). Spontaneous action potentials arising from the pinealocytes were recorded by means of glass micropipettes filled with 3 M NaCl containing a dye. The electrical stimulation of suprachiasmatic nucleus, superior cervical ganglia, sciatic nerve and retina evoked discharge changes in a significant number of pineal cells. However, a relatively higher proportion of pinealocytes failed to respond to these afferents. Three types of responses could be observed. Inhibitions were the predominant response patterns to suprachiasmatic nucleus, superior cervical ganglia and sciatic nerve, while excitations were mainly elicited following photic stimulation, whereas the remaining evoked activity was biphasic responses, which were observed in a small number of cells after stimulation of suprachiasmatic nucleus, superior cervical ganglia and retina. These data confirm some previous neural inputs to the pineal and demonstrate the existence of a modulatory effect of the suprachiasmatic nucleus on pinealocyte discharges as well as somatosensory afferents to the gland by way of the sciatic nerve.

Action Potentials↗
PubMed1991

Investigation of cis/trans proline isomerism in a multiply occurring peptide fragment from human salivary proline-rich glycoprotein.

The solution-state conformations of eight proline-containing peptide fragments found in human salivary proline-rich glycoprotein (PRG) were investigated in 2 x distilled water (treated with metal ion chelating resin) using 13C-nuclear magnetic resonance (NMR) and circular dichroism (CD) spectroscopy. The peptide sequences and acronyms were as follows: PRG9-2 = NH2-G(1)-P(2)-CONH2, PRG9-3 = NH2-G(1)P(2)-P(3)-CONH2, PRG9-4 = NH2-G(1)-P(2)-P(3)-P(4)-CONH2, PRG9-5 = NH2-G(1)-P(2)-P(3)-P(4)-H(5)-CONH2, PRG9-6 = NH2-G(1)-P(2)-P(3)-P(4)-H(5)-P(6)-CONH2, PRG9-7 = NH2-G(1)-P(2)-P(3)-P(4)-H(5)-P(6)-G(7)-CONH2, PRG9-8 = NH2-G(1)-P(2)-P(3)-P(4)-H(5)-P(6)-G(7)-K(8)-CONH2 and PRG9-9 = NH2-G(1)-P(2)-P(3)-P(4)-H(5)-P(6)-G(7)-K(8)-P(9)-CONH2. Sequence-specific resonance assignments from the 13C-NMR spectra indicated that the trans proline isomer dominated the conformations of the peptides. CD results clearly showed the presence of the poly-L-proline II helix as the major conformation in PRG9-3----PRG9-5, supplemented by beta- and/or gamma-turns in PRG9-6----PRG9-9. These data suggest that in "metal free" water, native PRG could contain several small poly-L-proline II helices along with beta- and/or gamma-turns. Since proline is the major amino acid present in native PRG, these localized conformations may contribute to PRG's global conformation and act as a primary force in determining its biological activities.

Circular Dichroism↗