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R Moncada

Publications and source records attributed to R Moncada.

At least 19 recordsLinked to original sources
PubMed1995

Flow cytometric evaluation of platelet activation by ionic or nonionic contrast media and modulation by heparin and recombinant hirudin.

RATIONALE AND OBJECTIVES: The purpose of this study was to investigate the platelet activation properties of ionic and nonionic contrast media in native heparinized or hirudinized human blood using flow cytometric analysis techniques. MATERIALS AND METHODS: Freshly drawn human blood samples were incubated at 37 degrees C with ionic (Hexabrix and Angiovist) and non-ionic (Isovue and Omnipaque) contrast media for varying periods of time. Using fluorescent monoclonal antibodies to platelet surface receptors glycoprotein IIIa and with granule membrane protein-140, platelet activation was measured in whole blood using flow cytometry. Platelet factor 4 and thromboxane B2 levels also were measured. RESULTS: Dose- and time-dependent platelet activation was observed in nonionic, but not in ionic, contrast media (P < 0.05). Whole blood drawn into heparin or hirudin showed reduced platelet activation in the presence of contrast media compared with nonanticoagulated whole blood. Platelet factor 4 and thromboxane B2 levels showed similar results. Significant platelet activation was seen by flow cytometry in high (2000 mOsmol/kg), but not in lower osmolality (800 mOsmol/kg) controls for ionic and nonionic contrast media, respectively (P < 0.001). CONCLUSION: This study suggests that nonionic contrast media use is associated with significant levels of platelet activation, and that heparin or recombinant hirudin (where heparin is contraindicated) is preferable for use with nonionic contrast media, as these anticoagulants reduce contrast media induced platelet activation.

Contrast Media↗
PubMed1991

Primary lymphoma of the heart. Prolonged survival with early systemic therapy in a patient.

Primary lymphoma of the heart is an uncommon malignancy usually recognized at autopsy or fatal within a few weeks of diagnosis. Recently, it was reported in patients with acquired immune deficiency syndrome. A patient with diffuse large cell lymphoma of the heart is reported who had chest pain and rapidly evolving cardiac arrhythmias. The human immune deficiency virus antibody test was negative. Because of an aggressive diagnostic approach, therapy with cyclophosphamide, doxorubicin, vincristine, and prednisone was started on the third day after diagnosis. The patient has survived 18 months with an objective response. To the authors' knowledge, this is the longest reported survival in primary cardiac lymphoma. The diagnosis in this patient was aided by excellent tumor delineation by nuclear magnetic resonance scanning. The authors believe that better survival in this patient was a result of prompt diagnosis and treatment because the behavior of the lymphoma was similar to aggressive lymphomas arising elsewhere.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1991

Biochemical evidence for a relative lack of inhibition of thrombin formation by nonionic contrast media.

An in vitro study was done to investigate the thrombogenic potential of nonionic contrast media. Whole blood from 18 healthy volunteers was mixed with ionic contrast medium (diatrizoate, ioxaglate), a non-ionic contrast medium (iohexol), or saline (the control) and incubated in glass and plastic test tubes. Levels of prothrombin fragment 1 + 2 (F1 + 2), thrombin-antithrombin III complex (TAT), and antithrombin III (AT III) were measured. Evidence showed increased thrombin formation in glass tubes compared with that in plastic tubes, a finding in concordance with the known association between contact with glass and increased activation of coagulation. F1 + 2 and TAT levels were significantly increased in the nonionic mixtures compared with such levels in ionic mixtures (P less than or equal to .05). Control mixtures showed little or no overall increased thrombin formation by F1 + 2 and TAT levels compared with nonionic mixtures. These findings suggest an inhibition of thrombin generation by ionic contrast media in vitro and a relative lack of such inhibition by iohexol.

Antithrombin III↗
PubMed1989

Contrast media-induced lipid peroxidation in the rat kidney.

Lipid peroxidation of biological membranes is often implicated in tissue injury. The authors compared the effects of ionic and nonionic contrast media (CM) on the induction of lipid peroxidation in rat kidney and its impact on renal function. Male Wistar rats weighing 200 to 230 grams were dehydrated for 24 hours and divided into 6 groups (n = 15/group). On day 0, groups 1 through 3 were injected with 25% glycerol (10 mL/kg, im) and rats from groups 4 through 6 received an equivalent amount of intramuscular saline. The next day, rats from groups 1 and 4 were injected with normal saline (10 mL/kg, iv); groups 2 and 5 received the ionic CM, diatrizoate, and groups 3 and 6 received the nonionic CM, iopromide. Each CM was tested at 10 mL/kg BW. At 24-hour intervals, 5 rats from each group were sacrificed. In rats injected with CM (diatrizoate or iopromide) alone, no changes in serum creatinine or kidney structure were demonstrated. In glycerol treated rats, a peak in serum creatinine was seen on day 2 which returned to normal level by day 4. Histologic changes included focal tubular damage and intraluminal debris. Malondialdehyde (MDA), a marker of lipid peroxidation concentration was higher than in controls (P less than 0.05). In diatrizoate-injected rats, increase in serum creatinine on day 4 was ten times higher than glycerol; severe morphological alterations in proximal tubules were noted and significant increases in renal MDA concentration were obtained (P less than .05). Iopromide (on day 4), caused a five-fold increase in serum creatinine compared with glycerol.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Computed tomography and magnetic resonance imaging of the pericardium.

Computed tomography is an established modality for the evaluation of the pericardium. It is used to evaluate complicated pericardial effusions, pericardial thickening, calcific pericarditis, pericardial cysts, postoperative changes and primary and metastatic neoplasms of the pericardium. Magnetic resonance imaging is being used with increasing frequency in the evaluation of pericardial disease. It offers advantages over computed tomography, including a potential for tissue characterization, absence of ionizing radiation or need for intravenous contrast medium, and the ability to scan in any plane. Disadvantages include greater cost, longer examination times and the inability to identify calcification positively.

Heart Neoplasms↗
PubMed1988

Cytogenetic interactions of contrast media and antineoplastic drugs.

The cytogenetic interactions of ionic (diatrizoate, ioxaglate) and nonionic (iohexol) contrast media (CM) with antineoplastic drugs cyclophosphamide (CPA) and carmustine (CARM) were evaluated in a rat bone marrow cell model. Male Wistar rats were anesthetized with a 6% chloral hydrate solution and divided into five groups of five rats each. In protocol 1, three groups of rats received diatrizoate, ioxaglate, and iohexol (2.5 mL/kg) intravenously within 30 seconds. The remaining two groups were similarly injected with CPA and CARM (10 mg/kg). Control animals were injected with nonpyrogenic sterile water or saline solution. After 12 and 24 hours, the animals were killed with an overdose of chloral hydrate, and bone marrow smears were prepared for determining chromosomal damage in polychromatic erythrocytes (PCEs) by a micronucleus test. In protocol 2, CPA and CARM were injected, and 15 minutes later, bolus injections of diatrizoate, ioxaglate and iohexol were given through the same route. Both ionic and nonionic CM induced significant numbers of micronuclei in PCEs (P less than .05). CPA caused a severe cytogenetic effect, whereas CARM did not produce a significant number of micronuclei in PCEs compared with control. In protocol 2 experiments, antagonism with CPA and synergism with CARM was demonstrable. Clinical implication of the cytogenetic interactions between CM and antineoplastic drugs remains to be established.

Animals↗
PubMed1988

Effect of contrast media on prostaglandin synthesis in vivo.

Since systemic reactions to contrast media (CM) in patients often resemble pathophysiologic conditions associated with prostaglandin metabolites prostacyclin (PGI2), and thromboxane B2 (TXB2), plasma levels of these mediators are likely to provide an index of CM pathogenesis. In this study, patients undergoing peripheral arteriography were injected either with a hyperosmolal CM sodium diatrizoate or with a newer low osmolal CM, iohexol. Arterial blood samples were collected before and after the procedure. Prostacyclin and thromboxane were quantified as 6 ketoprostaglandin F1a (PGF1a) and TXB2 by using radioimmunoassay kits. Diatrizoate caused prostaglandin I2 (PGI2) release in 60% of patients, whereas 66% receiving iohexol also exhibited increased levels of PGI2 in their plasma. TXB2 concentration remained unchanged. No clinically adverse reactions were seen following the procedure. These results indicate that both high and low osmolality CM are capable of stimulating vascular endothelium, thereby causing prostacyclin release. Molecular mechanisms, however, remain to be determined.

Adult↗
PubMed1987

Induction of mitotic micronuclei by X-ray contrast media in human peripheral lymphocytes.

In vitro and in vivo cytogenetic effects of X-ray contrast media (CM) were determined by scoring micronuclei (MN) in 72-h cultures of human peripheral lymphocytes. Both ionic (sodium meglumine diatrizoate, methylglucamine diatrizoate, and sodium meglumine ioxaglate and nonionic CM (iosimide, iopromide, iohexol and iotrolan) were able to induce MN in lymphocytes. Based upon their calculated percent probabilities for MN induction, these agents could be ranked in their decreasing order of probability, as iosimide greater than sodium meglumine ioxaglate greater than iohexol greater than sodium meglumine diatrizoate greater than iopromide greater than methylglucamine diatrizoate greater than iotrolan. Stepwise logistic regression analysis of the data indicated that the frequency of MN in CM-exposed lymphocyte cultures was significantly higher than the frequency of MN in control cultures (P less than 0.001). In clinical studies where 14 patients were injected with an ionic CM methylglucamine diatrizoate, lymphocyte cultures from 10 patients showed higher frequencies of MN. The differences between pre- and post-CM counts of MN were significant in a Mann-Whitney U test (P less than 0.05). The effect of X-irradiation on MN formation in lymphocytes was separately determined and was found to be insignificant. These results indicate that irrespective of ionic and osmolality differences, X-ray contrast agents are capable of producing chromosomal damage in peripheral lymphocytes. Further studies are required to establish molecular mechanisms in the observed cytogenetic effects of CM in cell cultures.

Age Factors↗
PubMed1987

Computed tomography of superior vena cava obstruction.

Which imaging procedure is best for the diagnosis of the superior vena cava (SVC) syndrome is subject to considerable debate. Available imaging procedures include the plain chest film, SVC phlebography, scintiangiography, digital phlebography, CT digital phlebography, and CT. In our experience the combined technique of contrast enhanced CT axial images, followed by a CT digital phlebogram, is the most informative, cost-effective, and least invasive method available.

Humans↗
PubMed1987

Catamenial pneumothorax: case report and literature review.

Since the initial case report in 1958, 69 cases of catamenial pneumothorax have appeared in English-language literature. Despite the extensive case material, the pathogenesis has not been fully elucidated. Herein an additional case is reported utilizing computed tomography (CT) to search for intrathoracic endometrial implants. The four major pathogenetic theories include passage of air from the genital tract via diaphragmatic defects, spontaneous rupture of subpleural blebs, intrathoracic endometriosis, and prostaglandin-induced bronchiolar constriction resulting in alveolar rupture. Evidence for and against each theory is presented.

Adult↗
PubMed1987

The role of percutaneous drainage of pancreatic abscesses.

Pancreatic abscess remains the most lethal form of intra-abdominal abscess despite a wide variety of operative approaches that have been advocated for its control. Mortality is frequent, and recurrent abscesses after operative drainage are common. Death often results from ongoing uncontrolled sepsis. The role of percutaneous drainage (PCD) of pancreatic abscesses is controversial. Recent experience with five patients who had pancreatic abscess and in whom a combination of operative drainage and PCD proved instrumental in survival leads the authors to recommend the consideration of both forms of drainage dependent upon the circumstances. Specifically, indications for PCD may include the following: use as a temporizing measure prior to celiotomy in a critically ill patient; use in postoperative patients who have recurrent abscesses and in whom the presence of dense inflammation precludes safe evacuation of pus; and use in the patient who has known portal hypertension and in whom massive bleeding is likely to result from celiotomy and abscess drainage.

Abdomen↗
PubMed1986

Radiologic diagnosis of an intra-abdominal abscess. Do multiple tests help?

A review was made of the charts of 94 patients who underwent ultrasonography (US), computed tomography (CT), and gallium citrate Ga 67 (Gall) scan to rule out intra-abdominal abscesses. Of all the clinical and laboratory data, only the presence of pain and tenderness differentiated patients with and without abscesses. A review of radiologic data showed that CT was superior to US, and that US was superior to Gall scan with regard to sensitivity, specificity, accuracy, and positive and negative predictive values. When multiple radiologic tests were performed, results agreed in 72% of cases; therefore, the additional tests were essentially redundant. When radiologic test results disagreed, accuracy rates were CT, 0.86; US, 0.00; and Gall scan, 0.44. These findings suggest that, except to rule out pelvic abscesses in the presence of pelvic inflammatory disease, CT is usually the only special radiologic test that should be performed to localize a suspected intra-abdominal abscess.

Abdomen↗
PubMed1986

Diagnosis of intrapericardial tumor in an infant by two-dimensional echocardiography.

Two-dimensional echocardiography is a useful noninvasive tool for diagnosing intrapericardial tumors as a cause of respiratory distress or abnormal cardiomediastinal shadow on chest x-ray. Early recognition of these tumors within the pericardium is important since surgical removal is often curative. Cardiac cineangiography is unnecessary to delineate further the tumor and should be reserved for those in which associated intracardiac defects are suspected.

Cysts↗