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Biomedical subjects

R Gonzalez

Publications and source records attributed to R Gonzalez.

At least 361 records · Page 20Linked to original sources
PubMed1981

Computed tomography in the diagnosis of pelvic abscesses in renal transplant patients.

Two renal transplant patients had fever and graft tenderness secondary to a gas-containing abscess around the transplanted kidney. Renal ultrasonography failed to identify the abscess in these cases because of the difficulty in differentiating bowel from gas-containing collections. Gallium citrate Ga 67 scanning, performed in one patient, did not delineate the abscess because interpretation was complicated by the presence of radioactivity in the bowel. In both cases, the pelvic abscess was identified correctly with the use of computed tomography (CT). The limitations of ultrasonography in identifying gas-containing collections should be recognized, and CT should be performed as one of the initial studies in evaluating a renal transplant patient with a suspected pelvic abscess.

Abscess↗
PubMed1981

The predictability of labor outcome from a comparison of birth weight and x-ray pelvimetry.

The value of x-ray pelvimetry in labor has recently been questioned by many, although few morphometric data on the fetopelvic relationship have been presented. Fifty-one women who had dysfunctional labor, in whom both x-ray pelvimetry and oxytocin were used during clinical management, were studied. Twenty-seven were delivered by cesarean section, while 24 were delivered vaginally. Regression equations were developed for multiple pelvic indices versus birth weight. The analysis revealed no differences between the vaginal group and the cesarean section group. The design of this study suggests that the variables of pelvic measurements and birth weight do not provide a predictive tool for delivery outcome. The approximately 15% margin of dimensional differences between a successful outcome and a failed outcome is too small to be detected by current diagnostic methods.

Adult↗
PubMed1981

Transvenous embolization of internal spermatic veins: nonoperative approach to treatment of varicocele.

Eleven men, shown on routine spermatic venography to have bilateral varicocele, underwent transjugular bilateral embolization of the internal spermatic veins with stainless steel coils or Ivalon plugs. Embolization of the left spermatic vein was successful in 9; in the other 2 it was not attempted because of aberrant drainage of the vein. Embolization of right spermatic vein was successful in 8 patients. There were three complications, none of which was serious. These preliminary results suggest that both internal spermatic veins can be occluded consistently by the transjugular approach. However, it has not yet been established that fertility is improved by detecting and correcting varicocele on the right side.

Embolization, Therapeutic↗
PubMed1981

Histopathological correlation of ultrasound appearances of liver metastases.

We reviewed ultrasound examinations of the liver performed at Yale--New Haven Hospital on patients with biopsy-proven tumors since January 1, 1977, to correlate the ultrasonic appearances with histology. Liver metastases appeared as sonolucent lesions in 37.5% of patients, as mixed sonolucent/echogenic lesions in 37.5%, and as solely echogenic in only 25%. We found a limited correlation between the echogenic pattern of the ultrasound scans and histology. The majority of echogenic metastases were from colonic primaries (54%) or hepatomas (25%). Metastases from lymphomas were extremely sonolucent and sarcomas frequently demonstrated central necrosis. Calcified metastases from mucin-secreting adenocarcinoma of the colon appeared as dense lesions with distal shadowing.

Adenocarcinoma↗
PubMed1981

Atrial and ventricular vulnerability in a patient with the Wolff-Parkinson-White syndrome.

An electrophysiologic study was carried out in a patient with the Wolff-Parkinson-White syndrome and a history of spontaneous atrial fibrillation but with no evidence of organic cardiac disease. A single induced premature ventricular depolarization resulted in ventricular tachycardia followed by ventricular fibrillation. Similarly, atrial pacing or premature atrial stimulation resulted in frequent episodes of atrial fibrillation or flutter. The atrial and ventricular effective refractory periods were 180 ms and less than 160 ms, respectively, at a driven cycle length of 480 ms. Intravenous administration of procainamide resulted in lengthening of the refractory periods and failure to induce either atrial or ventricular arrhythmias with pacing. In most patients with enhanced atrioventricular nodal or accessory atrioventricular nodal by-pass, the mechanism of ventricular tachycardia is related to an inordinately rapid ventricular response during supraventricular arrhythmias. In our patient, a unique mechanism was apparent: atrial and ventricular vulnerability to fibrillation was associated with extremely short myocardial effective refractory periods. The relationship of this finding to sudden cardiac death bears further study.

Adult↗
PubMed1981

Embolization of the spermatic vein for treatment of infertility: a new approach.

A new transjugular technique for spermatic venography and nonsurgical transcatheter occlusion of incompetent spermatic veins is described. With this technique, the left spermatic vein was easily catheterized in 28 of 30 patients examined, and in 21 patients the vein could be occluded. Right spermatic vein catheterization was attempted in 25 patients. Right-sided spermatic vein occlusion was successful in 17 of 24 patients. The vein could not be selectively entered only twice. Bilateral incompetence of the spermatic veins in men with primary sterility is the rule rather than the exception. Valvular incompetence does not necessarily produce a clinically detectable varicocele. Bilateral venography is indicated in all men with abnormal spermiograms.

Adult↗
PubMed1981

Closed-chest electrode-catheter technique for His bundle ablation in dogs.

A modified quadripolar electrode catheter that had two-thirds of the distal surface insulated with high-voltage plastic was inserted in 10 dogs. After a His bundle potential had been recorded, a synchronized direct-current electrical discharge was delivered between the electrodes showing the largest His bundle deflection using a standard direct-current defibrillator, and a metallic plate was positioned over the dog's back. Complete atrioventricular (AV) block was induced in 9 of 10 dogs, which were followed for 3 mo before being killed. During AV block, the QRS complex was broad and not preceded by a His bundle deflection. The mean control cycle length during AV block was 1,441 +/- 223 ms and decreased to 1,151 +/- 181 ms after exercise, a response that was usually abolished by beta-blockade. Overdrive pacing resulted in pacemaker suppression with gradual rate stabilization after 10-20 beats. There was no evidence of myocardial or valvular damage. This technique provides for a stable model of complete AV block and is suitable for experiments in which heart rate control is required. In addition, this technique may be of value for patients with tachycardia requiring His bundle section.

Angiography↗
PubMed1981

His-ventricular dissociation in a patient with reciprocating tachycardia and a nodoventricular bypass tract.

A patient with recurrent bouts of atrial fibrillation and wide-complex regular tachycardia underwent electrophysiologic studies. Premature atrial stimulation or atrial pacing during sinus rhythm resulted in gradual lengthening of the PR and AH intervals, narrowing of the HV interval and progressive preexcitation with a left bundle branch block and left-axis contour. Induction of tachycardia was dependent on critical delay in the atrioventricular interval and was associated with attainment of a maximal preexcitation pattern. During tachycardia, the ventriculoatrial interval was constant, whereas the interval from His bundle deflection to the ventricular complex was variable. We postulate that the tachycardia circuit involved reciprocation within the atrioventricular node and that a nodoventricular bypass tract was present in close anatomic or functional association with the slow atrioventricular nodal pathway. Our data suggest that both the nodoventricular bypass tract and the His-Purkinje system may be passive "bystanders" rather than essential components of the tachycardia circuit. In addition, although HV dissociation usually implies ventricular tachycardia, this case demonstrates that HV dissociation during wide-complex regular tachyarrhythmia is not diagnostic of ventricular tachycardia.

Adult↗
PubMed1981

Effect of a calcium inhibitor, nifedipine, on exercise tolerance in patients with angina pectoris: a double-blind study.

The effect of nifedipine on exercise tolerance was studied in 30 patients with stable angina and positive graded exercise testing. Treadmill exercise testing was performed on each of five consecutive days. Placebo or nifedipine, 10 mg sublingually, was given 30 minutes before exercise on the third day. The following day the intervention was reversed in a double-blind manner. Angina was abolished by nifedipine but not by placebo in 12 patients (40 percent). The time to onset of angina in the remaining patients increased from 4.1 +/- 0.4 (SEM) to 6.7 +/- 0.6 min (p less than .001). Time to ST depression greater than or equal to 2 mm increased from 4.0 +/- 0.3 to 5.4 +/- 0.5 min, while duration of exercise increased from 6.3 +/- 0.3 to 8.2 +/- 0.4 min (p less than .001). The maximum heart rate was 145 +/- 3.3 with nifedipine and 122 +/- 3.8 min-1 with placebo (p less than .01). Resting systolic blood pressure decreased 30 min after nifedipine administration from 131 +/- 3.4 to 106 +/- 2.9 mm Hg (p less than .01). Maximal systolic blood pressure during exercise was lower with nifedipine (127 +/- 4.8 mm Hg) than with placebo (155 +/- 5.6 mm Hg, p less than .01). We conclude that nifedipine significantly improves the exercise tolerance of patients with stable angina pectoris by decreasing peripheral vascular resistance and myocardial oxygen demand.

Adult↗
PubMed1981

Cardiovascular collapse associated with disopyramide therapy.

Five patients with severe left ventricular failure, renal insufficiency, and recurrent ventricular tachycardia had cardiovascular collapse and died eight hours to 23 days after initiation of the usual doses of disopyramide. Three patients had recent myocardial infarction (12 to 33 days), and one had severe congestive cardiomyopathy. ECG changes antedated appearance of cardiovascular collapse and consisted of lengthening of the QRS (0.10 plus or minus 0.02 to 0.22 plus or minus 0.09; P less than 0.025) and the QTc duration (0.44 plus or minus 0.04 to 0.56 plus or minus 0.09; P less than 0.05). Sinus bradycardia or varying degrees of atrioventricular block or both occurred in all patients. Terminal disopyramide blood concentration (4.9 and 8.1 micrograms/ml) were available in two patients. A syndrome of progressive lengthening of ventricular depolarization and repolarization terminating in cardiovascular collapse and death associated with disopyramide is described. In addition, a high incidence of sinus bradycardia, atrioventricular conduction disturbances, or both was also noted. Disopyramide is contraindicated in patients with severe heart failure and renal insufficiency. Progressive widening of the QRS complex or the QT interval may presage appearance of severe myocardial dysfunction.

Administration, Oral↗
PubMed1981

Treatment of supraventricular arrhythmias with intravenous and oral verapamil.

Verapamil or placebo was administered as a bolus infusion in a double-blind fashion to 24 patients with either atrial fibrillation or flutter and to ten patients with paroxysmal supraventricular tachycardia. Patients whose heart rate did not decrease below 100 beats/min were given a second dose. Of the 24 patients with atrial fibrillation or flutter, 11 received placebo first. Control heart rate and blood pressure were not modified by placebo; however, verapamil significantly reduced heart rate and systolic blood pressure in the 24 patients. Of the ten patients with paroxysmal supraventricular tachycardia, one reverted to sinus rhythm after administration of placebo. For the remaining nine, the heart rate was not modified by placebo but was significantly reduced by verapamil administration. Blood pressure was not modified by verapamil or placebo in these ten patients. Long-term oral verapamil treatment was maintained without interruption in 18 patients for a mean of 16 +/- 7.5 months, and 15 patients required concomitant therapy with other antiarrhythmic drugs for rhythm control. All patients reported symptomatic improvement, and the number of hospitalizations required for arrhythmia control decreased significantly. Verapamil is safe and effective for acute control of supraventricular arrhythmias. Long-term oral administration, alone or with other antiarrhythmic drugs, is an important contribution to the management of recurrent supraventricular arrhythmias.

Administration, Oral↗
PubMed1981

A specific method of high sensitivity for the determination of adenosine in the incubation medium of fat tissue.

A suitable method for the measurement of adenosine in the incubation medium of fat tissue (200-500 mg) has been developed. The method is based on the specificity of the adenosine deaminase reaction and on the high sensitivity of a fluorescent method for adenine derivatives. The decrease of fluorescence in a sample after treatment with this enzyme is used for measuring adenosine in the range of 50-500 pmoles/tube. This method is highly specific and is not affected by other adenine derivatives present in the sample. Instead of acetic acid, perchloric acid was used in the fluorescent reaction, thus increasing the amount of adenosine dependent fluorescence. With this modification of the original fluorescent method, perchloric acid extracts can be used without further processing after deproteinization of the samples. Using this method, we could measure the adenosine release of fat pads of Wistar rats incubated in Krebs-Ringer-albumin buffer without concentration or purification procedures.

Adenosine↗
PubMed1981

Significance of adenosine for the hormone responsiveness of adenylate cyclase in adipose tissue of normoglycemic and hyperglycemic sand rats.

In young sand rats, bred in our colony, the metabolism was directed from the normoglycemic state by means of feeding conditions. The noradrenaline action on adenylate cyclase is impaired in hyperglycemic, hyperinsulinemic sand rats. Generally, addition of adenosine to the in vitro system eliminates the responsiveness of the adenylate cyclase to noradrenaline in adipose tissue. The presence of adenosine deaminase in the incubation medium abolished this inhibition effect of added adenosine. The interference of released adenosine with the hormone action in vitro was excluded by addition of adenosine deaminase to the incubation medium. In both groups of sand rats adenosine deaminase did not increase the noradrenaline effect on adenylate cyclase. Investigations were carried out as a part of the research project "Diabetes mellitus and diseases of fat metabolism". These results along with the others on the measured adenosine release exclude adenosine as a reason for the disturbed hormone action on adenylate cyclase in hyperglycemic, hyperinsulinemic sand rats.

Adenosine↗
PubMed1981

Effects of tunicamycin on B16 metastatic melanoma cell surface glycoproteins and blood-borne arrest and survival properties.

The role of cell surface glycoproteins in determining in vivo blood-borne arrest and survival characteristics of murine melanoma sublines of low (B16-F1) or high (B16-F10) potential to form experimental lung metastases after injection i.v. was assessed after inhibiting tumor cell protein glycosylation with tunicamycin. Incubation of B16-F1 or B16-F10 cells with 0.5 micrograms (or above) tunicamycin per ml for 12 to 36 hr inhibited significantly lung tumor colony formation. Examination of B16 cells in the presence of 0.5 micrograms drug per ml indicated that complex oligosaccharide synthesis was inhibited greater than 90%, while protein synthesis remained at about 50% of the control levels. Tunicamycin induced morphological changes in B16-F1 and B16-F10 cells such as cellular rounding. Cell growth was also inhibited by tunicamycin. These effects were reversible, and B16 cells recovered their normal morphologies and growth rates within 24 hr after removal of the drug. Exposed cell surface protein analyzed by lactoperoxidase-catalyzed 125I iodination-sodium dodecyl sulfate-polyacrylamide gel electrophoresis-autoradiography showed few changes after tunicamycin treatment; however, sialogalactoproteins (detected by the binding of 125I-labeled R. communis agglutinin I to polyacrylamide gels containing desialized B16 cell surface components) were reduced dramatically by the drug. The adhesive properties of untreated and tunicamycin-treated B16 cells were assessed by the binding of 51Cr-labeled B16 cells to endothelial cell monolayers. Tunicamycin-treated B16-F1 and B16-F10 cells adhered at lower rates to endothelial cells such that after 24 to 36 hr of drug (0.5 micrograms/ml) treatment adhesion was almost completely blocked, suggesting that tunicamycin-induced cell surface glycoprotein changes in B16 melanoma cells may interfere with tumor cell-host cell interactions that lead to arrest and survival of blood-borne malignant cells.

Animals↗