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Biomedical subjects

R Reyes

Publications and source records attributed to R Reyes.

At least 19 recordsLinked to original sources
PubMed1992

Intraparenchymal anesthesia infiltration during transjugular intrahepatic portosystemic shunting.

The authors describe a technique for administration of anesthetic to the area of the transparenchymal tract during transjugular percutaneous transhepatic portosystemic shunting. Seven of the eight patients in whom the technique was used did not experience pain during balloon dilation of the tract, and one patient experienced only minimal pain. The technique allows good pain control in patients with severe liver failure and resultant inability of the liver to metabolize pharmaceuticals.

Aged↗
PubMed1992

Cellular mechanism of metformin action involves glucose transporter translocation from an intracellular pool to the plasma membrane in L6 muscle cells.

The effects of the oral hypoglycemic drug metformin on glucose and amino acid transporter activity and subcellular localization of GLUT1 and GLUT4 glucose transporters were tested in cultured L6 myotubes. In muscle cells preexposed to maximal doses of metformin (2 mM, for 16 h), 2-deoxyglucose uptake was stimulated by over 2-fold from 5.9 +/- 0.3 to 13.3 +/- 0.5 pmol/min.mg protein. Uptake of the nonmetabolizable amino acid analog methylaminoisobutyrate was unaffected by treatment with the drug under identical conditions. Extracellular calcium was required to preserve the full response to the biguanide. Exposure of muscle cells to insulin in the presence of metformin resulted in further activation of 2-deoxyglucose transport. The latter effect was additive to the maximum effect of metformin, suggesting that the biguanide stimulates hexose uptake into muscle cells by an insulin-independent mechanism. Glucose transporter number quantified by performing studies of D-glucose-protectable binding of cytochalasin-B in plasma membranes (PM) and internal membranes (IM) prepared from L6 myotubes revealed that a 16-h treatment with 800 microM metformin significantly elevated glucose transporter number in the PM (by 47%), with an equivalent decrement in glucose transporter number (47%) in the IM. Western blot analysis using antisera reactive with the GLUT1 and GLUT4 isoforms of glucose transporters showed that metformin caused a reduction in GLUT1 content in the IM fraction and a concomitant increase in the PM. Unlike insulin, metformin treatment had no effect on the subcellular distribution of GLUT4. We propose that the molecular basis of metformin action in skeletal muscle involves the subcellular redistribution of GLUT1 proteins from an intracellular compartment to the plasma membrane. Such a recruitment process may form an integral part of the mechanism by which the drug stimulates glucose uptake (and utilization) in skeletal muscle and facilitates lowering of blood glucose in the management of type II diabetes.

Aminoisobutyric Acids↗
PubMed1992

[Bilateral Leydig cell tumor].

A 7 year old boy presented with bilateral nodular testicular swelling, adult penis development and scrotal aspect. Laboratory studies revealed a bone age of 13 years, increased testosterone, estradiol, DHEA-S, and 17 ketosteroids levels. The GnRH test revealed puberal findings. Biopsy was consistent with Leydig cell tumor with presence of Reinke crystals. After enucleation of the tumor signs of necrosis and malignancy were shown. Orchiectomy will follow as chemotherapy and radiotherapy have been reported to be without value.

Child↗
PubMed1991

[The treatment of obliterating arteriopathy of the lower limbs with Simpson's Atherocath].

Percutaneous transluminal angioplasty is limited by a high percentage of restenosis in the medium and long runs. Other arterial recanalization systems to be combined with or to be used in alternative to angioplasty are under investigation. Atherectomy with Simpson's catheter (Atherocath) allows mechanical removal of the atheromatous plaque, leaving a smooth lumen, and vessel dilatation with the same effects as those of angioplasty and coaxial Dotter catheters. A Hundred and ten atherectomies with Atherocath were performed by the authors in 103 patients for the treatment of 77 stenoses and 33 total occlusions. All patients had 36 months' follow-up. Immediate and medium patency rates are encouraging in femoropopliteal arteries; the actual role of the method in iliac arteries is still to be demonstrated. Atherectomy with Aterocath can be useful not only in the treatment of arterial stenoses, but also in complete obstructions, in combination with angioplasty. Other relevant indications are the removal of partially or totally obstructive intimal flaps complicating angioplasty, and treatment of such ulcerated lesions as the blue-digit syndrome.

Adult↗
PubMed1990

Use of Gianturco self-expandable stents in the tracheobronchial tree.

Gianturco self-expandable stents were used successfully in the management of 5 patients with tracheobronchial pathology. Placement was performed under endoscopic and fluoroscopic guidance. None of the patients has experienced complications secondary to the stent placement, and in all of them the clinical problems resolved satisfactorily. Longer follow-up is required to determine the place of tracheobronchial stenting in patients with respiratory compromise.

Aged↗
PubMed1990

The Simpson atherectomy catheter in the management of complete obstructions.

The Simpson atherectomy catheter has been used successfully to recanalise eleven complete occlusions of the iliac and femoropopliteal arteries. Atherectomy and angioplasty were used in combination in 8 cases. Following atherectomy, all patients showed clinical improvement. Distal pulses returned in 7; rest pain and/or claudication disappeared in the other 4. Ischaemic ulcers healed in the 2 affected patients. Overall, ankle-arm indices (AAI) improved by an average of 0.43, with the improvement being greatest (0.55) in patients in whom the lumen was recanalised to within 91-100% of the native luminal diameter. Seven patients have remained with stable AAI values and without change in their clinical status at 18 months follow-up.

Adult↗
PubMed1990

Glycosaminoglycan-sulfate as plasma membrane component of pig spermatozoa.

The effect of specific glycosaminoglycan-hydrolyzing enzymes on the ruthenium red staining of pig spermatozoa was studied. Washed spermatozoa were incubated at 35 degrees C in buffer or with neuraminidase 0.5 units/ml, heparinase 0.2 mg/ml, or chondroitinase ABC 2.0 units/ml. After incubation sperm cells were washed, stained with ruthenium red and studied under the electron microscope. Anionic sites in the surface of untreated spermatozoa follow regularly the plasma membrane, but present are numerous processes constituting what has been defined as the glycocalyx. Neuraminidase did not affect the distribution of ruthenium red on the surface of the spermatozoa, but eliminated almost completely the processes of the glycocalyx. Heparinase caused loss of the ruthenium red-stained sites on the membrane surface of pig spermatozoa with less influence on the dense processes of the glycocalyx. A similar loss of ruthenium red-stained sites was observed with nitrous acid treatment. A striking effect of treatment with chondroitinase ABC was the production of a typical acrosome reaction.

Animals↗
PubMed1989

Heparin and glutathione: physiological decondensing agents of human sperm nuclei.

It has been proposed that reduced glutathione (GSH) or other thiol reagents may participate in the basic mechanism by which sperm-decondensing activity is accomplished. However, in vitro, these reagents seem to be inactive and require the presence of other chemicals, usually detergents. Heparin binds specifically to the sperm membrane and provokes the decondensation of human sperm and the activation of DNA transcription and synthesis. However, the concentrations at which these effects occur seem to be higher than those expected under physiological conditions. In the present study, thiol reagents at 10 mM concentration, either alone or combined, were completely ineffective in inducing any significant nuclear decondensation after prolonged exposures (24 hr) of incubation. Heparin, 153.8 microM, was capable of inducing only a small increase in nuclear swelling. However, GSH at concentrations as low as 0.1 mM in combination with heparin induces decondensation of human sperm nuclei in vitro. When GSH concentration was kept constant at 5 mM, nuclear decondensation was induced with heparin at concentrations as low as 11.6 microM, and a maximal decondensation (90%) was obtained with only 21.6 microM of heparin. The latter is more than ten times less than the minimal active concentration of heparin used alone.

Cell Nucleus↗
PubMed1989

Percutaneous atherectomy as an alternative treatment for postangioplasty obstructive intimal flaps.

Intimal flaps are commonly seen angiographically after percutaneous balloon angioplasty. Nonobstructive flaps are normally of little clinical significance, but flaps that obstruct blood flow may lead to partial or complete thrombosis. The Simpson atherectomy catheter was used to treat obstructive intimal flaps after angioplasty in four patients. Lumen patency was reestablished in all four cases. The clinical results were excellent, with rest pain and claudication resolved in all four patients and distal pulses reestablished in one. These findings suggest that the Simpson atherectomy catheter can be used to remove large obstructive flaps complicating angioplasty.

Aged↗
PubMed1989

Percutaneous transluminal angioplasty as best treatment in stenosis of vascular access for hemodialysis.

We show the results of treatment with percutaneous transluminal angioplasty on 38 occasions for vascular access for hemodialysis. Our study includes 22 patients with A-V internal fistulas (Cimino type), 1 autologous saphenous vein shunt and 7 synthetic polytetrafluoro-ethylene shunts. Twenty patients have had a follow-up period over 24 months. Four patients required a second and 2 of them a third transluminal dilatation. Only on two occasions were complications related to the technique. The microscopic findings of the venous wall after percutaneous transluminal angioplasty are shown.

Adult↗
PubMed1988

Size-uniform heparin fragments as nuclear decondensation and acrosome reaction inducers in human spermatozoa.

Using size- uniform mixtures of di-, tetra-, octa- and decasaccharides obtained from the depolymerization of heparin with heparinase, we have studied the activity that these low molecular weight heparin fragments may have on the acrosome reaction and sperm nuclei decondensation processess. Swelling of human spermatozoa nuclei was stimulated by heparin and their fragments and was dependent on the incubation time and directly correlated with the size of the fragment tested. Disaccharides were unable to increase the number of swollen nuclei. At short times (2-8 hrs) decasaccharides were the most active substances tested, including heparin. Only heparin and the tetra- and decasaccharides showed a significant increase in the number of acrosome-reacted spermatozoa, both fragments were more active than heparin at 2 hour incubation. Hexa- and octasaccharides induced a slight increase in the number of acrosome reacted spermatozoa and disaccharides were ineffective. The presence in animal systems of oligosaccharides derived from macromolecules and having specific biochemical properties, remembers the recent discovery of to those mediated by oligosaccharins in plants may exist in animals.

Acrosome↗
PubMed1988

Esophageal strictures: balloon dilation.

One hundred seventy transnasal balloon catheter dilation procedures were performed in 35 patients with esophageal strictures to assess the efficacy and safety of the procedure. On the average, five dilations were required per patient. Depending on the cause of the esophageal stricture, success rates for the technique ranged from 67% to 87%, with success defined as the resolution of dysphagia to both fluids and solids. Three complications, all perforations, were seen; one perforation required surgical repair. No procedure-related deaths were identified in this series. Balloon catheter dilation can be safely applied to esophageal strictures from a variety of causes, with a high degree of clinical success.

Catheterization↗
PubMed1988

Human immunodeficiency virus infection in the Republic of Panama.

Thirty-one documented acquired immune deficiency syndrome (AIDS) cases occurred in Panama during 1984-1987. Twenty-three (74%) patients were homosexual males and all but 2 patients recognized prior to June 1987 have died. To identify risk factors for human immunodeficiency virus infection, 287 male homosexual residents of Panama City were enrolled in a cross-sectional study. Nine had human immunodeficiency virus (HIV) antibody. Travel to the United States, homosexual relations with United States nationals in Panama, and sexual contacts in Panamanian clubs and bars were associated with human immunodeficiency virus infection by logistic regression analysis. Number of different male sex partners per year was identified but did not enter the logistic model at a significant level. To estimate seroprevalence in other high risk populations, 183 Panama City female prostitutes and 55 homosexual males from the rural Azuero peninsula were screened; none were seropositive. Eighty-four percent of Panamanian hemophiliacs had antibody; infection was related to factor VIII transfusions. Two of 182 sickle cell anemia patients and 15 of 7,720 volunteer blood donors were positive.

Acquired Immunodeficiency Syndrome↗