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Biomedical subjects

J Fernandez

Publications and source records attributed to J Fernandez.

At least 181 records · Page 10Linked to original sources
PubMed1987

A new bioprosthesis for aortic and mitral valve replacement: preliminary evaluation of the Tascon valve.

The Tascon valve, a new porcine bioprosthesis, features a detachable sewing ring designed to facilitate insertion and removal. Between April 1984 and June 1986, we implanted the Tascon valve in 25 patients, 12 of whom underwent aortic valve replacement (AVR), and 13 of whom had mitral valve replacement (MVR). Most of the patients were in NYHA class III or IV. Four MVR patients had had previous mitral valve operations, and three AVR patients required composite graft valved conduits. The valve's screw-locking mechanism worked well in all cases, especially in the AVR cases. There were no hospital deaths, and no significant morbidity or valve-related complications were encountered. One late death occurred 3 months after surgery, owing to causes unrelated to the valve. At the end of the study period, most of the survivors had improved by at least two NYHA functional classes. Postoperative aortic and mitral valve gradients and mitral valve areas, as measured by Doppler methods, were excellent. No significant regurgitation was detected. These favorable results indicate that the Tascon valve is a safe, useful bioprosthesis, with satisfactory hemodynamic characteristics.

Journal Article↗
PubMed1987

Four methods to recruit renal functional reserve.

The acute changes in creatinine clearance (Ccr) in response to intravenous amino acid infusion and to oral meat and milk protein meals were studied in seven healthy control subjects (Acute study). Para-aminohippurate clearance (CPAH), Ccr, inulin clearance (Cin), and plasma renin activity (PRA) were measured in seven different healthy control subjects following 1 week of low-protein diet, 0.7 g/kg per day, and again after one week of high-protein diet, 2.0 g/kg per day (Chronic study). In the acute study Ccr increased to a similar extent with each of the three stimuli, 20.1 +/- 6.2% (SD), 12.6 +/- 6.2% (SD) and 19 +/- 6.2% (SD) with amino acid infusion, 80-g meat protein and 80-g milk protein meals respectively. In the chronic study Ccr was 21%, Cin 26%, CPAH 8%, and filtration factor (FF) 14% greater during the high-protein diet than the low-protein diet, while PRA was increased by 43% on the high-protein diet. We conclude that an 80-g protein oral meal is probably sufficient to elicit the maximum acute increase in Ccr, since all three acute responses were similar, and similar in degree, to those previously reported, and may therefore be of value in measuring maximal filtration capacity. In contrast to one previous report, meat and milk proteins induced similar changes in Ccr. Thus milk protein cannot be regarded as a dietary substitute for meat in any diet designed to reduce glomerular hyperfiltration. Renin may play a part in the increase in glomerular filtration rate through the action of angiotensin II on the efferent arteriole, increasing filtration fraction.

Adult↗
PubMed1987

Strut fracture and other events after valve replacement with the 60 degree convexoconcave Björk-Shiley prosthesis.

A total of 688 patients received 808 Björk-Shiley prostheses during a 5 year span. Cumulative duration of follow-up totaled 1175.4 patient-years (1368 valve-years). Linearized rates in percent per patient-year for valve-related events (95% confidence limits) were: strut fracture, 0.5 (0.00 to 1.03); infective endocarditis, 0.94 (0.39 to 1.49); thromboembolism, 2.2 (1.37 to 3.052); valve impingement, 0.3 (0.00 to 0.77); and anticoagulant-related hemorrhage, 3.1 (2.15 to 4.14). No valve thrombosis occurred. Actuarial patient survival, including in-hospital mortality, was: aortic valve replacement, 79.8 +/- 3.4%; mitral valve replacement, 71.7 +/- 4.9%; double valve replacement, 59.8 +/- 7.5%. Incremental risk factors for death were age over 65 (p = .001), preoperative infective endocarditis (p = .04), and associated procedures (p = .0002). Although this prosthesis carries a low risk of infective endocarditis and thromboembolism, concern has been raised regarding its structural integrity.

Actuarial Analysis↗
PubMed1986

Plasma glucagon levels in different species of fish.

Plasma glucagon levels in 11 different teleosts and in dogfish were evaluated using an adapted classical mammalian radioimmunoassay (RIA). The values obtained are considered relative; sensitivity was inferior to the original method, but the validation experiment results are acceptable. The mean value of the coefficient of the variation for interassay was 6% and for intraassay 4%, recovery was 98%, and a good linearity in the dilution test was found. Some species (Sparus aurata and cyprinids) presented high plasma glucagon concentrations (0.50-1.60 ng/ml) versus the lower levels (0.08-0.40 ng/ml) found in salmonids and others, and the lowest in dogfish (0.02-0.20 ng/ml). A positive correlation (P less than 0.02) between insulin and glucagon plasma levels was found in different species. The low levels obtained in all parameters analyzed in the selachian were remarkable. This adapted RIA could serve as a useful tool in amplifying knowledge on the endocrine pancreatic response in fish in different biological situations.

Animals↗
PubMed1986

Simultaneous appearance of endocardial late potentials and ability to induce sustained ventricular tachycardia after procainamide administration.

We describe a patient in whom procainamide induced the appearance of late potentials during intraoperative sinus rhythm electrogram mapping. Only nonsustained ventricular tachycardia (VT) could be induced while off all antiarrhythmic drugs. After administration of the procainamide, programmed stimulation induced sustained VT coincident with the appearance of late potentials during sinus rhythm. The late potential was recorded from the same site, during normal sinus rhythm, where mid to late diastolic activation during VT was recorded, and where cryotermination occurred during cryomapping. We hypothesize that procainamide slowed conduction, manifested as prolongation or appearance of late potentials in sinus rhythm, and facilitated induction of sustained reentrant ventricular tachycardia.

Adult↗
PubMed1986

Increased potassium permeability in erythrocytes from patients with hyperparathyroidism.

Parathyroid hormone (PTH) has been shown to modify Ca2+ and Na+ transport in several epithelia. The molecular mechanisms of these effects are poorly understood. We investigated here whether PTH may modify Na+ and K+ transport across the human red blood cell membrane in vitro and ex vivo. Fourteen patients with severe primary or secondary hyperparathyroidism and hypercalcemia were studied before and 5-7 days after surgical parathyroidectomy. Erythrocyte ouabain-sensitive as well as furosemide-sensitive Na+ efflux rates of the patients were comparable to that of healthy volunteers and remained unchanged after parathyroidectomy. Moreover, erythrocyte Na+ fluxes of control subjects remained unchanged when red blood cells were incubated in the presence of 1.0 IU/ml of bovine PTH (1-85). However, erythrocytes from hyperparathyroid patients showed a significant increase in passive K+ permeability when compared to that of healthy controls (p less than 0.05). This abnormality could be corrected in vivo after parathyroidectomy and in vitro using quinine, respectively. It is concluded that hyperparathyroidism induces a moderate increase in Ca2+ dependent K+ permeability of erythrocytes ("Gardos effect") which is reversible after parathyroidectomy.

Adult↗
PubMed1986

Antibodies to AIDS-associated retrovirus (HTLV-III/LAV) in drug addicts from Vizcaya, northern Spain.

Serum samples from 313 asymptomatic intravenous (IV) drug users from Bilbao (Vizcaya, Vasque Country, Spain) were tested for antibodies to HTLV-III/LAV virus, the probable etiologic agent of the acquired immune deficiency syndrome (AIDS). Viral antibodies were assayed by ELISA test. 41.9% of the sera gave positive reactions. No seropositivity was detected among 22 normal blood donors, 58 chronic alcoholics, or 20 members of the Drug Control Center personnel. Virus specific reactions were confirmed by indirect immunofluorescence using an HTLV-III/LAV producer cell line, and by Western blotting. 55% of the ELISA-positive sera were also positive in Western blot assay. No differences in seropositivity by age or sex were observed but it increased with the period of parenteral drug use. Presence of antibody statistically correlated with the frequency of syringe sharing, confirming the transmission of viral infection by blood products. Altered T4/T8 ratios and lower number of T4 positive lymphocytes were detected among HTLV-III/LAV positive drug addicts.

Adolescent↗
PubMed1986

Prothrombin Segovia: a new congenital abnormality of prothrombin.

A family with a new congenital dysprothrombinemia is presented. The propositus is a 21-yr-old man who presented simultaneously with hemartrosis of the left knee and an extensive hematoma following a minor trauma. Prothrombin time and activated partial thromboplastin time were prolonged. Prothrombin activity was very low when measured by biological assay using physiological activators (7% by one-stage method and 20% by two-stage method) or a Russel's viper venom-cephalin mixture (23%), Notechis scutatus scutatus venom (15%) and Echis carinatus venom (17%); in contrast, the level was found to be borderline to normal using Taipan viper venom (64%) and normal by both staphylocoagulase and immunologic methods. Family studies revealed consanguinity between the propositus' mother and father and both presented a 50% reduced prothrombin level when physiological activators or Echis carinatus viper venom were used. A line of identity between normal and abnormal prothrombin was observed on immunodiffusion. The migration of the abnormal prothrombin was less anodic and was not changed by the addition of calcium. The patient's serum showed 3 bands in the bidimensional immunoelectrophoresis system, whereas normal serum showed only 2 bands. The term prothrombin Segovia is proposed to define this new prothrombin abnormality.

Adult↗
PubMed1986

Impaired extrarenal disposal of an acute oral potassium load in patients with endstage renal disease on chronic hemodialysis.

The relative importance of renal versus extrarenal mechanisms in the impaired potassium homeostasis in the various stages of chronic renal failure remains undefined. We evaluated potassium homeostasis after an acute oral load of potassium chloride (0.25 mEq/kg body weight) in 10 patients with end-stage renal disease on chronic hemodialysis and 8 control subjects. The maximal increment in plasma potassium concentration in the patients (1.06 +/- 0.13 mEq/1) was significantly higher than that of controls (0.39 +/- 0.1 mEq/1). When expressed as a percentage of the retained load, the patients translocated less potassium into cells (21 vs. 51%). Four of the patients exhibited no apparent transfer of potassium into cells, all the administered load remaining in the extracellular fluid compartment. The extrarenal abnormality does not appear to be related to acidemia, hyperglycemia, or abnormalities in insulin secretion. We conclude that patients with end-stage renal disease undergoing hemodialysis exhibit impaired extrarenal mechanisms of potassium disposal.

Acid-Base Equilibrium↗
PubMed1985

Rest-exercise radionuclide angiographic assessment of left ventricular function in chronic aortic regurgitation: significance of serial studies in medically versus surgically treated groups.

Forty consecutive asymptomatic patients with chronic aortic regurgitation who underwent three serial yearly rest and postexercise radionuclide angiograms were compared with 27 consecutive patients with chronic aortic regurgitation and aortic valve replacement who were studied preoperatively, 3 and 15 months postoperatively. Patients were divided into four subgroups based upon the resting left ventricular ejection fraction and the functional reserve on the initial study. Of the 40 medically treated patients, 19 (47.5%) and 24 (60%) demonstrated a response at least one type lower at 12 months and 24 months, respectively. Initial functional reserve, initial duration of exercise, and the change in exercise duration during the 24 months was not associated with changes in resting or postexercise left ventricular ejection fraction. A seesaw pattern was observed between the resting and the postexercise left ventricular ejection fraction as ventricular function deteriorated. We observed in the surgical groups a reversal of the seesaw interaction between the resting and postexercise ejection fraction seen in the medical patients. In the surgical groups the left ventricular end-diastolic pressure, initial functional reserve, initial duration of exercise, and change in exercise duration postoperatively were not predictors of improvement in left ventricular function at 15 months. Comparing medical and surgical serial data, we suggest yearly radionuclide angiographic determination of rest left ventricular ejection fraction in asymptomatic patients with chronic aortic regurgitation. When the rest ejection fraction is less than 50%, exercise angiography should be performed to determine functional reserve. When functional reserve is also abnormal, surgery should be recommended.

Adolescent↗
PubMed1985

Inherited haemorrhagic disease with abnormal prothrombin consumption.

The propositus is a 4-year-old boy who presented with a history of excessive bleeding after surgical procedures as well as haematomas and epistaxis. The defect in haemostasis consisted in an anomaly of the prothrombin consumption tests as the only abnormality while all the other conventional coagulation and fibrinolysis tests as well as platelet function tests were normal. The father of the propositus had no previous history of excessive bleeding but was found to have an abnormal prothrombin consumption index. The reaction to prothrombin conversion, normal at onset, slowed down to less than normal and did not reach completion until 24 h. The in vivo studies suggest that the effect does not act on the interaction between platelet phospholipid and plasma. The factor II dosage and the electrophoretic mobility of prothrombin of the plasma were normal; nevertheless when studying the purified prothrombin by means of crossed immunoelectrofocusing there appeared an anomaly of pI. This result suggests the possible existence of an abnormal prothrombin molecule responsible for a slow prothrombin conversion.

Blood Coagulation Disorders↗
PubMed1985

Cryothermal mapping of recurrent ventricular tachycardia in man.

Intraoperative reversible cryothermal mapping of recurrent ventricular tachycardia was performed in seven patients with left ventricular aneurysms with use of a 0 degrees C ice probe. A single, reproducible cryotermination site was found in each patient. The cryotermination site was uniformly located in an area where local electrograms obtained during ventricular tachycardia showed electrical activation during the diastolic portion of the surface electrocardiogram, and was different than the site of activation coincident with the onset of the QRS complex on the surface electrocardiogram (earliest reactivation site or ERS) by 4.5 +/- 2.7 cm (mean +/- SD) in five of seven patients. Sinus rhythm late potentials were recorded at the cryotermination site in five of six patients and from the ERS in one. In five patients, extensive subendocardial resection including both the ERS and cryotermination sites was performed. In two patients only the cryotermination site was excised. In six survivors, including one in whom only the cryotermination site was excised, ventricular tachycardia could not be induced 2 weeks after surgery and has not recurred during the follow-up period of 7 to 17 months (12 +/- 4.5 months, mean +/- SD). Reversible cryothermal mapping may provide additional important information not obtained by standard electrogram mapping of ventricular tachycardia that may help guide surgical therapy of recurrent ventricular tachycardia.

Cold Temperature↗
PubMed1983

Anatomic and clinical analysis of 96 Beall prostheses explanted over a 13-year period.

Over 13 years, 96 Beall prostheses (80 Teflon, 16 Pyrolite) explanted at surgery were examined for durability, material wear, and clinical symptoms leading to surgical indication for excision were evaluated. The Teflon valves showed progressive disc wear and notching and two cases of disc escape from the cage; the Pyrolite discs were intact in all prostheses. The Dacron-Velour covering common to both types showed dehiscence at the inlet, significantly more severe after the third implant year in the Teflon (p less than 0.005) than in the Pyrolite prostheses. Sixty-nine (85 percent) cases with Teflon valves showed clinical manifestations of congestive heart failure due to prosthetic dysfunction; in 50 there was significant hemolytic anemia. Seven (44 percent) of the 16 Pyrolite disc valves were excised primarily because of dysfunction. The degree of hemolysis with the Pyrolite valves was usually mild. These data clearly suggested the advisability of early excision of the Beall Teflon prostheses in symptomatic patients and a close follow-up in patients with the Pyrolite models.

Adult↗
PubMed1983

Fontan operation: modification of the valve position in conduit with brief review of the literature.

A Fontan operation was performed on a 10-year-old child for correction of tricuspid atresia. A xenograft, valved conduit was used to establish continuity between the right atrium and the small right ventricle. Atrial and ventricular septal defects were repaired with Dacron patches. Two hours postoperatively, the patient suffered a cardiac arrest secondary to hypoxia and was successfully resuscitated. Partial recurrence of a right-to-left shunt at the atrial level necessitated the patient's return to surgery. The insufficient conduit was replaced and the leaking patches were resutured. The conduit was shortened to one-third its length, and the conduit valve was repositioned directly at the proximal end, over the right atriotomy. Ten months postoperatively, the patient remains in stable condition.

Journal Article↗
PubMed1983

Transient hypogammaglobulinemia in the adult. Functional assessment of T and B lymphocytes.

The woman described suffered from a pruritic erythematous rash, edema, malaise and fever which appeared during Tegretol therapy. The patient was shown to have a severe hypogammaglobulinemia with absence of circulating B lymphocytes, but normal cell-mediated immunity. There was an absence of in vitro immunoglobulin production by the patient's cells, but this was not due to excessive T-suppressor activity or lack of T-cell help. When drug administration was stopped the edema and rash began to recede promptly, and a few months later her serum immunoglobulin levels, antibody titers and in vitro immunoglobulin production became normal. This transient, probably drug-dependent case of hypogammaglobulinemia, added to three previously reported cases, stresses the need of considering non-conventional immunosuppressive drugs as a potential-etiological agent in acquired hypogammaglobulinemia.

Adult↗