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Biomedical subjects

R Fernandez

Publications and source records attributed to R Fernandez.

At least 109 records · Page 6Linked to original sources
PubMed1991

A Y-chromosomal DNA fragment is conserved in human and chimpanzee.

A human male-specific Y-chromosomal DNA fragment (lambda YH2D6) has been isolated. By deletion-mapping analysis, 2D6 has been localized to the euchromatic portion of the long arm (Yq11) of the human Y chromosome. Among great apes, this fragment was found to be conserved in male chimpanzee but was lacking in male gorilla and male orangutan. No homologous fragments were detected in females of orangutan, gorilla, chimpanzee, or human. Nucleotide sequence analysis indicated the presence of partial-Alu-elements and of sequences similar to the GATA repeats of the snake Bkm sequence.

Animals↗
PubMed1991

Neuroendocrinology of chronic renal failure and renal transplantation.

Neuroendocrine activity in normal subjects was compared to patients with chronic renal failure on maintenance hemodialysis (CRF-HD) and to cyclosporine-treated renal transplantation (RT) recipients in an effort to further define the mechanisms underlying their associated fluid, electrolyte, and hemodynamic abnormalities. To evaluate neuroendocrine function in CRF and RT patients, plasma levels of angiotensin II (A-II), vasopressin (AVP), atrial natriuretic peptide (ANP), neuropeptide Y, neuropeptide Y (NPY), epinephrine (E), and norepinephrine (NE) were measured before and after HD and RT. Plasma concentrations of A-II, AVP, ANP, and NPY were significantly elevated in patients with CRF. HD did not produce a significant change in plasma concentrations of AVP, ANP, NPY, E, or NE. NE plasma levels, but not E levels, increased pre- and post-HD. A-II plasma levels were elevated basally in CRF patients and significantly increased following HD. Following RT, plasma levels of A-II, AVP, NPY, and creatinine decreased significantly over the first week, but AVP and NPY did not normalize. Plasma levels of ANP were elevated during the first month, then decreased to normal levels in RT patients. NE levels, but not E levels, were elevated both pre- and post-RT. Despite antihypertensive treatment, the group mean arterial pressure increased post-RT from 100 +/- 4.4 to 116 +/- 3.7 mmHg by POD 6.

Adult↗
PubMed1991

[Neurophysiopathology of spinal lesions, evaluation of the 80s. Post-injury assessment and treatment of the neurogenic bladder in the acute period].

This introductory presentation deals with the recent pathophysiological aspects of the post-traumatic spinal cord lesion and the population concerned. The neurophysiology of the bladder and its sphincters is summarized so as to try and explain some disturbances occurring during the acute phase following a spinal cord injury; their clinical and urological aspects and the methods of bladder drainage.

Acute Disease↗
PubMed1990

Conformational changes of peroxidase and albumin in solutions of propylthiouracil.

Conformational changes of peroxidase and albumin in buffered solutions of propylthiouracil, an antithyroid drug, were evaluated by dialtometry and viscometry, showing that the structural alteration of peroxidase is related to the decoupling of the reactions which it catalyses. Thus, propylthiouracil probably inactivates the peroxidase by altering its structure. Equilibrium dialysis showed that albumin is the principle propylthiouracil-transporting protein in human serum. Propylthiouracil induces a conformational change in albumin when 1 mole of drug per mole of protein is bound, a structural alteration that can change the binding capability of other ligands.

Chemical Phenomena↗
PubMed1990

Bronchial migration of pulmonary arterial coil.

Transcatheter embolization was performed with stainless steel coils in a patient with bilateral pulmonary arterial aneurysms of unknown etiology. After a successful initial procedure, endobronchial migration of one of the coils was found which required surgical treatment. Indications of embolization and different types of materials are discussed.

Adolescent↗
PubMed1990

Expanding the role of the ureteroscope.

Although the rigid ureteroscope was designed exclusively for the diagnosis and treatment of pathological conditions of the ureter, its smaller diameter and extended length allow for its increased use in endoscopic procedures that cannot be performed successfully with a cystoscope. The indications can be divided into 3 categories: 1) difficult ureteral catheterizations, 2) augmented bladders and diverticula, and 3) narrow, strictured urethras and bladder necks. Several cases from each category are presented to illustrate the expanded role of the rigid ureteroscope in daily urological practice.

Adult↗
PubMed1990

Endotracheal tube cuff pressure assessment: pitfalls of finger estimation and need for objective measurement.

Estimation of endotracheal (ET) cuff pressure by finger palpation is one of the methods currently used in the clinical setting. We compared the accuracy of this method with instrumental intracuff pressure measurement in tracheal model tests by 20 members of our ICU team. Four different ET tubes at three different pressure levels were examined. Accuracy for the estimated method by finger palpation was 69% for high pressures, 58% for normal pressures, and 73% for low pressures. We observed differences in terms of sensitivity, specificity, and positive predictive power between different tubes reflecting differences in tube characteristics and interobserver variability. We conclude that precise intracuff pressure measurement is mandatory to prevent complications of over- or underinflation.

Clinical Competence↗
PubMed1989

Dominantly inherited olivopontocerebellar atrophy from eastern Cuba. Clinical, neuropathological, and biochemical findings.

A form of dominantly inherited olivopontocerebellar atrophy (OPCA) occurs commonly in persons of Spanish ancestry in northeastern Cuba. Its prevalence in the Province of Holguin is 41 per 100,000, a figure much higher than that found in western Cuba or in other parts of the world. The high prevalence is probably the result of a founder effect, but might be due to an interaction between a mutant gene and an unidentified environmental neurotoxin. We describe the clinical features of this disorder, and the neuropathological abnormalities in 7 autopsied patients. In addition, we report biochemical findings in plasma, cerebrospinal fluid (CSF) and urine obtained from 10 living OPCA patients. Quantitation of amino acids in fasting plasma showed a number of differences between the Cuban patients and healthy Canadian controls, but these are likely to have been caused by dietary differences. Amino acid concentrations in the CSF of the Cuban OPCA patients were similar to those of healthy Cuban controls, except for a decreased concentration of ethanolamine. Mean concentrations of dopamine metabolites were significantly low in the CSF of the OPCA patients, corresponding to neuronal depletion observed in the substantia nigra of autopsied cases. Examination of the patients' urines provided no evidence that either cyanide or 3-acetylpyridine is involved in causing this form of OPCA.

Adult↗
PubMed1989

Hepatic artery anastomotic stenosis after transplantation: treatment with percutaneous transluminal angioplasty.

Two orthotopic liver transplant recipients underwent percutaneous transluminal angioplasty (PTA) for stricture of the hepatic arterial anastomosis. In both, arterial revascularization was effected by end-to-end anastomosis between the donor common hepatic artery and the recipient's hepatic artery. Both patients had elevated liver enzyme levels, abnormal results on duplex Doppler images, and severe stricture on angiograms. In one patient, percutaneous biopsy revealed graft ischemia. PTA was performed successfully without complications. PTA produced substantial improvement in biochemical, duplex Doppler, histologic, and angiographic patterns. Both patients were asymptomatic 5 and 6 months after PTA.

Adult↗
PubMed1988

MHC-restricted recognition of immunogenic T cell epitopes of pertussis toxin reveals determinants in man distinct from the ADP-ribosylase active site.

The S1 subunit of Pertussis toxin (PT) is responsible for the reactogenicity and in part the immunogenicity of Bordetella pertussis vaccine. The critical residues associated with the immunomodulatory effects of PT were located around Glu140 in the S1 subunit. In man, T cell responses to PT are directed at S1 peptides distinct from Glu140. Two such epitopes, p64-75 and p151-161, are immunogenic in a panel of individuals covering a wide range of HLA genotypes. The response to PT peptides is HLA class II restricted. The response to p64-75 is blocked by an anti-HLA-DQ mAb, while that to p151-161 is blocked by an anti-HLA-DR mAb. These findings may allow for the development of a B. pertussis vaccine free from reactogenicity.

Amino Acid Sequence↗
PubMed1988

Purification, characterization, and pathogenicity of Moraxella bovis pili.

Pilins composed of the alpha or beta pilins of Moraxella bovis strain Epp63 were purified, subjected to chemical or enzymatic cleavage, and the resulting fragments sequenced by automated Edman degradation. alpha Pilin was found to be a 155-amino-acid polypeptide with a single intramolecular disulfide bridge. The beta pilin amino acid sequence substantiated the previously reported structure derived from the beta pilin gene DNA sequence, and indicated that the alpha and beta pilins of this strain are approximately 70% homologous. DNA hybridization studies of genomic DNA from the alpha- and beta-piliated variants of strain Epp63 indicated that the expression of the two pilin types was governed by an oscillating mechanism of chromosomal rearrangement. The alpha and beta pili were evaluated serologically and found to exhibit approximately 50% shared antigenicity, indicating that regions of conserved and heterologous sequence specify both type-specific and crossreacting epitopes. The pathogenicity of the alpha- and beta-piliated variants was studied by ocular inoculation of calves eyes; beta-piliated organisms were significantly more infectious than alpha-piliated organisms, indicating that beta pili confer, or are associated with, a relative advantage during the first stages of ocular infection. Preliminary analysis of other M. bovis strains suggests that each strain produces two types of pilin, and that this property may be characteristic of the species.

Amino Acid Sequence↗
PubMed1988

Purification of isocitrate lyase from Saccharomyces cerevisiae.

Isocitrate lyase purified to homogeneity from Saccharomyces cerevisiae was composed of four identical subunits with a molecular mass of 75 kDa. The enzyme was most active at pH 7.0 in the presence of 5 mM-Mg2+. The Km value for threo-Ds-isocitrate was 1.4 mM. Isocitrate lyase was shown to be thermostable at 50 degrees C for 60 min at a high salt concentration, but rapidly lost activity at -20 degrees C or by dialysis.

Chromatography, Gel↗
PubMed1988

Value of proximal diversion and ureteral stenting in management of penetrating ureteral trauma.

Cases of penetrating ureteral trauma (17 gunshot wounds and 4 stab wounds) seen at two New York City hospitals over a nine-year period were reviewed. Early urologic complications (defined as urine drainage from the wound for greater than 2 weeks or need for a second operation) occurred in 50 percent of patients with a proximal ureteral injury but were less common when a nephrostomy and stent were used in the repair. A similar beneficial effect of stenting was seen in published cases, with a 91 percent complication rate for unstented repairs and a 15 percent rate when stenting and nephrostomy drainage were both used. The effect of stenting on midureteral repairs was less obvious, but the rate of urologic complications was lower in stented cases. None of the patients with distal ureteral injuries suffered a urologic complication. Stenting with and without a nephrostomy tube also produced good results in 2 patients with proximal ureteral injuries diagnosed late. We conclude that repair of penetrating ureteral injuries should include stenting and nephrostomy tube drainage in cases of proximal injuries, as well as generous debridement and water-tight closure. Midureteral injuries accompanied by gastrointestinal, pancreatic, and major vascular injuries should be stented and proximal diversion considered when prosthetic materials are used for vascular repairs.

Adolescent↗
PubMed1988

Middle latency response to a 500-Hz tone pip in normal-hearing and in hearing-impaired subjects.

Measurement of middle latency responses (MLR) appears to be one of the most useful ways of determining low-frequency auditory threshold. It is known that analog filtering can drastically affect MLR and since most laboratories use different recording characteristics, we carried out these measurements with a number of filter configurations. Ten subjects with normal hearing sensitivity were tested. The stimuli were 500-Hz tone pips (alternating in polarity) with a 4-ms rise-fall time and a plateau of 2 ms, presented at the rate of 9.3/s. The MLR were recorded with filter settings of 10-100, 10-250, 10-1,500, 10-3,000, 30-100 and 30-250 Hz at 12 dB per octave roll-off with a time base of 100 ms. MLR threshold was found between 8.0 and 11.5 dB nHL. The Wilcoxon statistical test showed that mean MLR thresholds did not differ significantly at the various bandpass configurations. An additional objective of this study was to compare hearing sensitivity based on MLR threshold to tone pips at 500 Hz and behavioural results obtained by conventional pure-tone audiometry. Although the correlation coefficient between the behavioural and electrophysiological measurements was statistically significant (r = 0.85), further studies are required in order to determine the real magnitude of the predicted errors obtained, before this electrophysiological measure can be applied clinically.

Adolescent↗
PubMed1988

Conservative operation for mitral stenosis. Independent determinants of late results.

A retrospective study was designed to define the independent determinants of late results in 282 consecutive patients operated on for mitral stenosis between 1978 and 1985. A total of 25 variables were investigated by multivariate discriminant analysis for their possible influence on symptomatic outcome, subsequent reoperation, postoperative thromboembolism, and death. All the patients underwent a conservative mitral valve operation. In addition, 25 patients required concomitant tricuspid annuloplasty. The surgical mortality rate was 1.4% and the late mortality, reoperation, and thromboembolism rates were, respectively, 0.14%, 0.80%, and 0.95%/pt-yr. Actuarial probability of complication-free survival at 8 years was 83% +/- 3.7%. Left atrial size on the M-mode echocardiograms, tricuspid annuloplasty, mitral annuloplasty, presence of left atrial thrombus, male gender, and separation of subvalvular apparatus portended a significantly higher likelihood of poor postoperative symptomatic status (p less than 0.0005). Preoperative mild mitral regurgitation, E to F slope on the M-mode echocardiogram, and tricuspid annuloplasty had significant influence on the need for late reoperation (p less than 0.05). Postoperative atrial fibrillation, mitral valve amplitude on the M-mode echocardiogram, preoperative embolism, and residual mitral incompetence had an independent predictive power for postoperative thromboembolism (p less than 0.05). Finally, preoperative atrial fibrillation, preoperative cardiothoracic ratio, postoperative left atrial size, and postoperative atrial fibrillation all influenced the probability of long-term complications. These results suggest that earlier operation should be considered in patients with mitral stenosis, to increase the complication-free survival rate.

Actuarial Analysis↗