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Biomedical subjects

J Marquez

Publications and source records attributed to J Marquez.

At least 37 records · Page 2Linked to original sources
PubMed1989

Interaction of nicotinic acetylcholine receptor with two monoclonal antibodies recognizing different epitopes.

The interactions of nicotinic acetylcholine receptor (nAChR) with two monoclonal antibodies (mAb370A and mAb371A) which block the agonist-induced ion flux into nicotinic acetylcholine receptor vesicles [Donnelly, D., Mihovilovic, M., Gonzalez-Ros, J. M., Ferragut, J. A., Richman, D., & Martinez-Carrion, M. (1984) Proc. Natl. Acad. Sci. U.S.A. 81, 7999] have been studied by a combination of immunochemical and spectroscopic techniques. Both mAbs are specific for the alpha-subunit of the receptor, but they recognize different epitopes. We have detected specific binding of the mAb370A to a synthetic peptide corresponding to residues alpha 187-205, a sequence known to contain the alpha-bungarotoxin binding site. By contrast, mAb371A seems to recognize an epitope which is largely silent after proteolytic digestion of the subunit. Binding of mAb370A to the receptor is inhibited by cholinergic agonist and alpha-neurotoxins but not by competitive antagonists or local anesthetics. By contrast, none of these ligands interferes with binding of mAb371A. The spectroscopic properties of the fluorescent probe ethidium have been used to investigate the effect of the mAbs on the interaction of the agonist carbamylcholine with nAChR in membranes. mAb370A, but not mAb371A, blocks both the agonist-induced increase in the fluorescence intensity of receptor-bound ethidium and the agonist-induced increase in the polarization value of the probe. In addition, measurements of ethidium binding followed by stopped-flow techniques showed that mAb370A, but not mAb371A, blocked the agonist-induced association of the probe to nAChR membranes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Hemichorea-hemiballismus associated with acquired immune deficiency syndrome and cerebral toxoplasmosis.

A young woman had hemichorea-hemiballismus subsequently found to be secondary to a cerebral toxoplasmosis infection complicating human immunodeficiency virus infection. This patient had the sixth reported case of acquired immune deficiency syndrome (AIDS) with hemichorea-hemiballismus, and each has been secondary to cerebral toxoplasmosis. The presence of hemichorea-hemiballismus in a young patient should suggest a diagnosis of AIDS and in particular the diagnosis of secondary cerebral toxoplasmosis. Other movement disorders that occur in AIDS are discussed.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Sch 38519, a novel platelet aggregation inhibitor produced by a Thermomonospora sp. Taxonomy, fermentation, isolation, physico-chemical properties, structure and biological properties.

The complex containing a new platelet aggregation inhibitor, Sch 38519, was recovered from the fermentation filtrate of Thermomonospora sp. SCC 1793. A chemically defined medium was developed which favored the production of Sch 38519. The antibiotic was isolated from the fermentation filtrate by absorption on macroreticular resin and further purified by ion exchange chromatography and reverse phase HPLC. Sch 38519 is an isochromanequinone structurally related to medermycin, lactoquinomycin and granaticin. It inhibits thrombin-induced aggregation of human platelets with an IC50 of 68 micrograms/ml. Sch 38519 is also active against Gram-positive and Gram-negative bacteria.

Actinomycetales↗
PubMed1988

Purification of phosphate-dependent glutaminase from isolated mitochondria of Ehrlich ascites-tumour cells.

Phosphate-dependent glutaminase was purified to homogeneity from isolated mitochondria of Ehrlich ascites-tumour cells. The enzyme had an Mr of 135,000 as judged by chromatography on Sephacryl S-300. SDS/polyacrylamide-gel electrophoresis displayed two protein bands, with Mr values of 64,000 and 56,000. Two major immunoreactive peptides of Mr values of 65,000 and 57,000 were found by immunoblot analysis using anti-(rat kidney glutaminase) antibodies. The concentration-dependences for both glutamine and phosphate were sigmoidal, with S0.5 values of 7.6 mM and 48 mM, and Hill coefficients of 1.5 and 1.6, respectively. The glutaminase pH optimum was 9. The activation energy of the enzymic reaction was 58 kJ/mol. The enzyme showed a high specificity towards glutamine. A possible explanation for the different kinetic behaviour found for purified enzyme and for isolated mitochondria [Kovacević (1974) Cancer Res. 34, 3403-3407] should be that a conformational change occurs when the enzyme is extracted from the mitochondrial inner membrane.

Animals↗
PubMed1988

Sch 37137, a novel antifungal compound produced by a Micromonospora sp. Taxonomy, fermentation, isolation, structure and biological properties.

A new antifungal compound, Sch 37137, was isolated from the cultured broth of a Micromonospora sp., SCC 1792. Sch 37137 is structurally related to A 19009, a dipeptide previously discovered from a Streptomyces sp. The compound was weakly active against species of Candida and dermatophytes (mean MICs greater than or equal to 128 micrograms/ml) in Sabouraud dextrose, yeast-nitrogen and modified Eagles minimum essential media; however activity against Candida sp. (mean MICs greater than or equal to 12 micrograms/ml) and dermatophytes (mean MICs greater than or equal to 0.8 microgram/ml) significantly improved in MA medium.

Amino Acids, Diamino↗
PubMed1988

Sch 36605, a novel anti-inflammatory compound. Taxonomy, fermentation, isolation and biological properties.

A novel anti-inflammatory compound, Sch 36605, belonging to the blasticidin family of nucleoside compounds was isolated from the fermentation filtrate of a Streptomyces sp. Sch 36605, as well as blasticidin S, demonstrated anti-inflammatory activity in the reverse passive Arthus reaction and the adjuvant arthritic rat at doses ranging between 1-10 mg/kg and 0.3-6.0 mg/kg, respectively. A minor component, Sch 366606, co-produced in the in the fermentation was isolated and identified as a known compound in the blasticidin family of compounds.

Animals↗
PubMed1987

Treatment of leiomyomata uteri with D-Trp6-luteinizing hormone-releasing hormone.

Suppression of the secretion of gonadal steroids by chronic administration of a superactive agonist of luteinizing hormone-releasing hormone (LH-RH) was used for treatment of leiomyomata uteri. Ten menstruating women, presenting with a total of 20 uterine leiomyomas, were treated for 3 months with daily subcutaneous injections of D-Trp6-LH-RH. Serum estradiol (E2) levels were suppressed rapidly in five patients and were decreased in other patients. At the end of therapy, leiomyomas regressed completely in three patients, while five patients showed a decrease of more than 40% in the volume of leiomyomas. The reduction in tumor size was correlated with the rapidity of the fall in serum E2 levels. In one patient, the leiomyomata increased in size during treatment, and one woman had a poor clinical response. The agonist was well tolerated and few side effects were observed. Therapy with LH-RH agonists offers an alternative in the management of some uterine leiomyomas.

Adult↗
PubMed1987

Ventricular assist by cardiac cycle-specific increases in intrathoracic pressure.

Changes in intrathoracic pressure can influence cardiac performance by altering ventricular loading conditions. Since ventricular loading, both from systemic venous return (preload) and from left ventricular wall stress (afterload), varies during the cardiac cycle, we reasoned that appropriately placed, phasic, cardiac cycle-specific (synchronous) increases in intrathoracic pressure might augment ventricular ejection in acute ventricular failure. Recent studies in animals suggest that synchronous increases in intrathoracic pressure during systole increase ejection. We compared the hemodynamic effect of synchronous increases in intrathoracic pressure with similar increases delivered at random in the cardiac cycle in patients with congestive cardiomyopathy (n = 9). Intrathoracic pressure was estimated by measuring esophageal pressure. High-frequency jet ventilation (HFJV) synchronized with the electrocardiogram (synchronous HFJV) was compared with HFJV at a fixed frequency within 15 percent of the heart rate (asynchronous HFJV) and with intermittent positive-pressure breathing (IPPB) (tidal volume = 10 ml/kg; f = 15). All forms of ventilation resulted in the same mean airway pressure and esophageal pressure. Mean pulmonary arterial occlusion pressure and arterial pressure were constant in all conditions. Cardiac output was greater with synchronous HFJV than with either IPPB or asynchronous HFJV (4.5 +/- 0.7 L/min compared with 3.5 +/- 0.7 and 3.4 +/- 0.6 L/min [mean +/- SE], respectively; p less than 0.05). Mixed venous oxygen saturation covaried with cardiac output (p less than 0.05), such that calculated oxygen consumption remained constant for all conditions. We conclude that synchronous HFJV augments cardiac output more efficiently than do similar increases in intrathoracic pressure delivered randomly in the cardiac cycle.

Adult↗
PubMed1986

Cardiovascular depression secondary to ionic hypocalcemia during hepatic transplantation in humans.

Cardiovascular function, serum ionized calcium (Ca+2), and serum citrate were measured intraoperatively in patients (n = 9) undergoing orthotopic hepatic homotransplantation. Serum citrate increased 20-fold (P less than 0.0006) following transfusion of citrated blood products in the absence of a functional liver. Serum ionized calcium decreased (P less than 0.003) with concomitant decreases in cardiac index (P less than 0.005), stroke index (P less than 0.004), and left ventricular stroke work index (P less than 0.001). Hemodynamic depression and ionic hypocalcemia were reversed following the administration of CaCl2. In contrast to patients with normal hepatic function, who may tolerate large amounts of citrated blood, patients with end-stage liver disease demonstrate acute ionic hypocalcemia with concomitant hemodynamic depression when receiving citrated blood products during the course of hepatic transplantation.

Calcium Chloride↗
PubMed1985

Intraoperative changes in blood coagulation and thrombelastographic monitoring in liver transplantation.

The blood coagulation system of 66 consecutive patients undergoing consecutive liver transplantations was monitored by thrombelastograph and analytic coagulation profile. A poor preoperative coagulation state, decrease in levels of coagulation factors, progressive fibrinolysis, and whole blood clot lysis were observed during the preanhepatic and anhepatic stages of surgery. A further general decrease in coagulation factors and platelets, activation of fibrinolysis, and abrupt decrease in levels of factors V and VIII occurred before and with reperfusion of the homograft. Recovery of blood coagulability began 30-60 min after reperfusion of the graft liver, and coagulability had returned toward baseline values 2 hr after reperfusion. A positive correlation was shown between the variables of thrombelastography and those of the coagulation profile. Thrombelastography was shown to be a reliable and rapid monitoring system. Its use was associated with a 33% reduction of blood and fluid infusion volume, whereas blood coagulability was maintained without an increase in the number of blood product donors.

Adult↗
PubMed1984

High-frequency jet ventilation in the postoperative period: a review of 100 patients.

One hundred patients were ventilated with high-frequency jet ventilation (HFJV) during the initial 24-h postoperative period in the surgical and neurosurgical ICUs. Eighty-three were successfully weaned, 2 could not be ventilated adequately with HFJV, and 15 with criteria of acute respiratory failure received HFJV for up to 21 days. A HFJV delivery system consisted of jetting and entrainment systems, both with their own humidification designs. An initial mode of HFJV using 35 psi, jet rate 100 cycle/min and inspiratory time 30% provided a mean PaCO2 of 34 torr in 38 patients studied. A comparison of HFJV without and with a positive end-expiratory pressure (PEEP) of 10 cm H2O indicated a decrease in mean Qsp/Qt from 17% to 13% with decrease in cardiac index (CI) from 3.39 to 2.81 L/min X m2; this effect is similar to PEEP applied to a conventional ventilator. Weaning proved to be simple and comfortable for the patient. In the light of our experience, we believe that HFJV is both feasible and practical for the postoperative patient and should be introduced into routine clinical use.

Adolescent↗
PubMed1983

Renal function and renin secretion during high frequency jet ventilation at varying levels of airway pressure.

The effect of positive end-expiratory pressure (PEEP) on plasma renin activity (PRA), renal function, and cardiovascular (CV) hemodynamics during high frequency jet ventilation (HFJV) was observed in 7 patients. The addition of PEEP during HFJV increased PRA while decreasing stroke index (SI) and cardiac index (CI). These changes were associated with decreased urinary flow, creatinine clearance, and fractional excretion of sodium. In contrast, HFJV at zero end-expiratory pressure (ZEEP) maintained normal PRA, renal function, and CV hemodynamics. The authors conclude that the alteration of renal function during HFJV is a function of airway pressure rather than the effects of the ventilatory frequency. The deterioration of renal function may have been due to changes in PRA or CV dynamics.

Adult↗
PubMed1981

Paradoxical cerebral air embolism without an intracardiac septal defect. Case report.

Cerebral air embolism occurred in a patient undergoing trigeminal rhizotomy in the sitting position. During the acute episode, a murmur was detected by the Doppler probe and foam was aspirated from the central venous catheter. The patient did not regain consciousness postoperatively, and computerized tomography demonstrated diffuse cerebral infarction. Subsequently, the patient died, and neuropathological examination revealed multifocal discrete infarcts in the gray and white matter with normal intervening brain. No intracardiac septal defects were present. This is the first fully documented case of cerebral air embolism of venous origin in the absence of intracardiac septal defects, and reemphasizes the hazards of operative procedures in the sitting position.

Embolism, Air↗