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Biomedical subjects

R Hernandez

Publications and source records attributed to R Hernandez.

At least 163 records · Page 9Linked to original sources
PubMed1989

Role of the gamma-glutamyl cycle in the regulation of amino acid translocation.

Amino acid translocation was studied in the mammary gland of lactating rats and in the placenta of pregnant rats. The uptake of amino acids by the mammary gland is maximal on days 10-14 of lactation and is minimal on days 19-21. However, on day 19 maximal uptake can be restored by injection of 1) small amounts of gamma-glutamyl amino acids, 2) 5-oxoproline, and 3) an inhibitor of 5-oxoprolinase. A severe decrease in uptake of amino acids at the peak of lactation is provoked by anthglutin, an inhibitor of gamma-glutamyltranspeptidase (GGT). Simultaneous injection of 5-oxoproline blocks these effects of anthglutin. In pregnant rats, inhibition (79%) of placental GGT activity by acivicin results in a 50% decrease of placental L-[U-14C]-alanine transfer and 70-80% decrease in its incorporation into the placental and fetal proteins. Infusion of 5-oxoproline to mothers previously treated with acivicin restored the L-[U-14C]-alanine transfer. Acivicin or 5-oxoproline did not modify the transfer and metabolism of D-[U14C]glucose by the fetal placental unit. These results show that the gamma-glutamyl cycle should not be considered a mechanism for amino acid transport but rather a generator of extracellular signals, gamma-glutamyl amino acids, that are converted intracellularly to 5-oxoproline, which activates uptake and/or metabolism of amino acids.

Alanine↗
PubMed1989

Evoked potentials suggest cranial nerves and CNS involvement in chronic relapsing polyradiculoneuropathy.

Brainstem auditory and visual potentials were recorded from 6 patients with chronic idiopathic polyradiculoneuropathy. Evoked potentials were either completely absent or their latency was prolonged suggesting slow conduction in visual or auditory pathways. The results of our study provide further evidence suggesting subclinical involvement of cranial nerves and central nervous system sensory pathways in chronic inflammatory demyelinating polyradiculoneuropathy.

Adult↗
PubMed1988

Species specificity of iron delivery in hybridomas.

Studies with Human X Human (H X H), Human X Mouse (H X M), and Mouse X Mouse (M X M) hybridomas have enabled us to define specific factors that affect hybridoma growth in a species-specific manner. Three transferrins and three lipophilic iron chelates have been tested for their ability to support hybridoma proliferation and antibody production. The results of these studies demonstrate that H X H hybridomas do not respond to bovine transferrin a+ concentrations up to 100 micrograms/ml and are approximately 100-fold less responsive to mouse transferrin than to human transferrin. H X M and M X M hybridomas respond equally to human or mouse transferrin but are 100-fold less sensitive to bovine transferrin. An antibody to the human transferrin receptor inhibited the growth-promoting activity of human or mouse transferrin on H X H hybridomas but was ineffective on H X M hybridomas. This demonstrated the functionality of the human transferrin receptor in H X H hybridomas and that human, mouse, and bovine transferrin were interacting through the mouse transferrin receptor in H X M hybridomas. H X H and H X M hybridomas respond similarly to three different iron chelates exhibiting 80 to 110% of the growth response to human transferrin. M X M hybridomas fail to respond to the iron chelates at similar concentrations, suggesting that the human genome present in the other hybridoma species confers a unique ability for utilizing iron when delivered in this form.

Animals↗
PubMed1988

Carotid endarterectomy in a general surgical training program.

Concern regarding the quality of surgical treatment performed within resident training programs and the need for direct, active involvement of the attending surgeon have been issues of interest to surgeons and the public. To provide specialized training in the diagnosis and treatment of vascular disease, vascular surgical fellowships have been established. In institutions with established vascular fellowships, one may question whether general surgical residents or vascular surgical fellows should perform carotid endarterectomies. The majority of carotid reconstructive procedures are performed at our institution by the chief general surgical resident under direct supervision. We elected to review our experience with surgical treatment of the carotid artery in an effort to examine the safety of this practice. The record of all patients who underwent carotid endarterectomy or reconstruction from April 1980 to July 1984 were reviewed. One hundred and twenty-nine patients who underwent 153 reconstructions of the carotid artery constituted the study group. The indication for operation was symptomatic carotid atheromatous disease in 96 and asymptomatic disease in 57. Ninety-three per cent of the procedures were performed by the chief general surgical resident under the supervision of one attending surgeon. Although the incidence of associated systemic problems (hypertension, diabetes and coronary artery disease) was significant in the study group, postoperative cardiovascular and cranial nerve and central neurologic deficits were 1.3 per cent, respectively, with no operative mortality. At our institution, the performance of carotid endarterectomy under close supervision provides an excellent context in which the resident in training may learn precise and careful dissection of the tissue and arterial repair. The need for formal vascular surgical fellowships to develop proficiency in judgment, technique and management of vascular disease is not questioned. However, as a learning experience for the general surgical resident, we believe this practice is both safe and effective, and a high standard of patient care is not compromised.

Carotid Arteries↗
PubMed1986

Enzyme immunoassay using BCG in serodiagnosis of pulmonary tuberculosis.

Amounts of Mycobacterium tuberculosis antibodies were determined in sera from patients with either active or inactive tuberculosis and in healthy subjects by an immunoenzymatic assay in which whole BCG cells attached covalently to polystyrene disks were used as antigen. Statistically significant differences (P less than 0.005) were found both between the active and inactive tuberculosis groups and between the active group and healthy controls. No significant differences were found between the inactive group and controls. Since this procedure is efficient (91%) and can be used in areas which lack laboratory equipment, it appears promising for individual serodiagnosis and for epidemiological surveys.

Antibodies, Bacterial↗
PubMed1985

Diagnostic dilemmas of mediastinal cysts.

Children with foregut cysts of the mediastinum can present at any age with nonspecific respiratory symptoms or dysphagia. Chest radiograph and barium esophagram are recommended for initial evaluation, but they fail to identify some lesions. In other cases, an obvious mass may be confused with a solid neoplasm. We have operated upon 34 infants and children with mediastinal bronchogenic cysts and esophageal duplications from 1968 through 1985. This review of their clinical course and radiographic imaging studies emphasizes some of the diagnostic pitfalls that lead to operative delay. Twelve (35%) of these patients were asymptomatic. The correct diagnosis was delayed longer than 3 months from the onset of symptoms in 14 of the 22 symptomatic children. Fifteen of these presented with pneumonia or symptoms or airway obstruction. In 11, the cyst was in a perihilar or subcarinal location, areas in which a lesion can be "hidden" behind the cardiac silhouette. Five children with esophageal duplication had severe neonatal respiratory failure, chest pain, hematemesis or dysphagia. The immediate preop chest radiograph revealed a mass in 29 of 34 cases. However, the lesion was initially missed or never seen in eight of those who were symptomatic. Esophagram, performed in 23, was diagnostic in only six and was normal in four. Prior to 1979 when CT scanning became available at this institution, 11 of 19 children (57%) underwent extensive work-up, but the preop diagnosis was correct in only 50%. Since 1979, only 4 of 15 (26%) have required similar evaluation, and the preop diagnosis has been correct in all.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1985

Therapeutic approach to the Pancoast pain syndrome.

The incidence of the Pancoast syndrome ranges from 2 to 5% of patients with lung cancer. We treated 20 cases between 1979 and 1984 with 29 procedures including percutaneous cordotomy, selective posterior radiculotomy, decompressive laminectomy, central administration of opiates, and TENS. Selective posterior radiculotomy gave the best pain relief.

Buprenorphine↗
PubMed1985

Therapeutic protocol in the treatment of trigeminal neuralgia.

The ideal treatment of trigeminal neuralgia is still an open question. A recent large series reporting the results from the three available percutaneous techniques has been reviewed. Fifty consecutive cases, treated from January 1984 to January 1985, are reported. Microcompression was performed as the first approach in all cases. The other techniques were adopted only in case of failure of microcompression.

Aged↗