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Biomedical subjects

R García

Publications and source records attributed to R García.

At least 19 recordsLinked to original sources
PubMed1992

Bone metal content in patients with chronic renal failure.

Bone accumulation of metals, other than aluminum (Al), in patients with chronic renal failure (CRF) has rarely been studied. We report the bone and blood levels of iron (Fe), vanadium (V), lead (Pb), Al and calcium (Ca) in 18 CRF patients on long-term hemodialysis and in 14 controls (C). Significant increments in mean blood Al (1,300%), V (160%) and Fe (60%) and decrease in blood Pb (-50%) were found in the patients with CRF. Renal subjects had higher bone concentrations (mean +/- S.E.M.; microgram/g of bone) of Al (CRF = 129.1 +/- 16.9; C = 12.6 +/- 2.9; P < 0.0001), Fe (CRF = 940.4 +/- 133.4; C = 263.4 +/- 49.0; P < 0.0001) and V (CRF = 2.55 +/- 0.43; C = 1.39 +/- 0.36; P = 0.0308) and lower Ca (CRF = 268.2 +/- 11.1 mg/g; C = 377.2 +/- 28.1; P = 0.0017). A positive correlation was found between bone Al and V (r = 0.355, P < 0.05). Results indicated that a significant bone accumulation of Al, Fe and V, but not Pb, occurred in the hemodialyzed azotemic individuals.

Adult↗
PubMed1992

Deposition and imaging of metal-coated biomolecules with the STM.

We have applied a simple and reliable procedure for imaging biomolecules with the scanning tunneling microscope (STM). The biomolecules are adsorbed on glow-discharged mica, then coated with a thin film of platinum-carbon. We have tested this method with linear and circular (plasmid) DNA molecules. The contrast and resolution of the STM images are comparable to electron micrographs of the same molecules when shadowed. Though the present lateral resolution (5-6 nm) is limited by the grain size of the conductive film, some details like supercoiled regions in the DNA are resolved. This method is interesting for two reasons. First, as an alternative technique for imaging biomolecules. Second, for use as a control in STM studies of bare biomolecules.

DNA↗
PubMed1992

A multiparametric study of malignant lymphoma of mucosa associated lymphoid tissue (MALT).

A morphological, immunophenotypic and ultrastructural study, cell cycle estimation, DNA and cytogenetic analysis were performed in ten cases of B-MALT lymphomas. Five had low grade lymphoma and five had high grade. Low and high grade cases showed the same cells but in different percentages: These included centrocyte-like cells with occasional monocytoid cytoplasmic changes, and centroblast-like cells. However, in high grade cases more dysplastic and large cells were present. All cellular types showed an important development of rough endoplasmic reticulum. In all cases a large panel of monoclonal antibodies was employed to study the B-cell immunophenotype. Ki-67 positivity ranged from 5% to 30% in low-grade cases and from 50% to 70% in high-grade cases. Gene rearrangement analysis showed rearrangement with Jh probe and half of the cases were also rearranged with the Kde probe (Kappa constant chain gene). A rearrangement banding pattern with TCR genes was not present in any of the cases. Cytogenetic study showed complex alterations in high grade cases and a normal karyotype in low grade lymphomas. Only one case had rearrangement for the bcl-2 probe.

Female↗
PubMed1992

RNA metabolism during the sexual differentiation of rat hypothalamus.

Modifications in the basal molecular biology parameters (total concentrations of RNA, DNA, proteins, rRNA, tRNa, free and polysomal bound poly-A+ mRNA) have been determined daily in the growing hypothalamus of male and female rats from day 1 to day 8 after birth. Changes observed in the parameters studied in this work occurred mainly in the first 48 h after birth. In males tRNA and free mRNA (f-mRNA) contents decreased from day 1 to day 2 and then their concentrations remained more or less constant. Total mRNA significantly decreased from day 1 to day 3 and showed a further significant decrease from day 6 to day 8. Polysomal bound-mRNA (b-mRNA) decreased from day 1 to day 3, then increased to day 6, and finally decreased once more from day 6 to day 8. The b-mRNA/f-mRNA, mRNA/rRNA and mRNA/total RNA ratios showed a bimodal behavior with a first peak on day 2, and a second, smaller peak, on days 6-7. The changes observed in the females on the first 2-3 days of life were the inverse of those observed in the males, most of the parameters studied showed a sharp increase from day 1 to day 2 or to day 3 and then a drastic decrease. The only exception to this behavior was the b-mRNA/f-mRNA ratio which showed a small decrease from day 1 to day 2, followed by a continuous increase from day 2 to day 8. b-mRNA concentrations, after the sharp decrease from day 2 to day 3 of life, increased from day 3 to day 7.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

[Acute early rejection in renal transplantation].

The incidence of early acute rejection (first two months after surgery) was evaluated in a group of 150 kidney transplants, receptors, who were followed for more than three months. Ninety nine were transplanted with kidney from a cadaver donor and 51 with living donor. One hundred forty two patients were treated with triple immunosuppression therapy (cyclosporine, prednisone and azathioprine). The incidence of early acute rejection was significantly higher in cadaver kidney receptors (34% vs 19.6%, p = 0.04. Fisher exact test). However, early rejection did not have demonstrable influence in graft or patient survival or in the follow-up graft function. Graft and patient survival were not affected by the severity of the rejection episode.

Acute Disease↗
PubMed1992

[Renal osteodystrophy in Maracaibo].

In the present work we report the bone histologies obtained from the iliac crest of 49 patients on chronic hemodialysis in Maracaibo. All of them were dialyzed thrice weekly with untreated tap water containing high aluminum (Al) levels. Their mean blood Al levels were found to be higher than 100 micrograms/L. Histomorphometry was used for the diagnosis of the underlying renal osteodystrophic type. Al-staining techniques (Aluminum) were applied for detection of bone Al deposits. Additionally, bone Al content was determined quantitatively by means of graphite furnace atomic absorption spectroscopy. A mixed type of osteodystrophy (type III according to Delling's classification) consisting in the simultaneous presence of hyperparathyroid bone lesions (osteitis fibrosa, OF) and a hyperosteoidosis (osteomalacia, OM) was found in 63.3% of the studied patients. The other patients (37.7%) exhibited a pure osteomalacia (OM). Bone Al deposits at the mineralization front were observed in 70% of cases and were frequently associated with bone pain, spontaneous fractures and skeletal deformities. We conclude that bone biopsy should be performed in all patients presenting bone pain and high blood Al levels.

Adolescent↗
PubMed1992

[Pregnancy in renal transplant recipients. Long-term evaluation of their children].

The course of eight pregnancies in seven renal transplant patients was analyzed. Immunosuppression consisted of Azathioprine and Prednisone. Pregnancy lasted from 32 to 39 weeks and the fetal development corresponded to the gestational age in every case. There were three cases which had complications during the pregnancy. One case had severe arterial hypertension, proteinuria and pedal edema, which was thought to be due to pre-eclampsia. Another patient had cholestatic jaundice and premature fissure of membranes and the third patient also had this last complication. Four patients had vaginal deliveries and in four cesarean section was performed. Renal function did not deteriorate during any of the pregnancies nor during the follow-up period, but the expected increase in creatinine clearance was not found. Clinical evaluation of the children, 4 months to 8 years of age, did not disclose any abnormalities.

Child↗
PubMed1992

[Sensitivity of the parietal cell to the effect of pentagastrin in men living at high altitude].

This study evaluates the response of the gastric mucosa to pentagastrin in a group (HAG) of 17 andean subjects compared to a similar group of 17 subjects at sea level (LAG). Both groups had normal fundic, body and antrum mucosa as demonstrated by endoscopic and histological means. Each group underwent two assays, the first one with a dose of 6 micrograms/kg and 72 hours later, the second administration with 3 micrograms/kg. In the HAG the acid response expressed as concentration and output was significantly greater with 6 micrograms/kg that with 3 micrograms/kg. In the LAG the difference was not statistically significant. The ANOVA analysis showed, for both determinations, free and total acidity, a different response pattern between the HAG and LAG for both doses. The response of both groups to the 3 micrograms/kg reveals a lesser sensitivity to pentagastrin of the parietal cell in HAG.

Adult↗
PubMed1991

[Usefulness of ketoconazole combined with cyclosporin in renal transplantation].

To reduce the cost of treatment in renal transplant patients, ketoconazole, an inhibitor of the cytochrome P-450 enzyme system, was added to their triple immunosuppressive treatment (prednisone, azathioprine and cyclosporine). Thirty seven patients were included; they received 100-200 mg/day of ketoconazole and the amount of cyclosporine given was adjusted to keep its whole blood concentration within a therapeutic range. The dose of cyclosporine was decreased 70.4% by the first month of combined treatment and 76% by the ninth month. The benefit obtained with this reduction allowed the use of cyclosporine to be extended to all the patients and to administer it permanently. In 3 patients the increase in the serum hepatic enzymes made us stop ketoconazole. In order to detect hepatotoxicity early, periodic monitoring of liver function tests is mandatory.

Adolescent↗
PubMed1991

Removal of trace metals by continuous ambulatory peritoneal dialysis after desferrioxamine B chelation therapy.

We studied the removal of aluminum (Al), iron (Fe), copper (Cu), lead (Pb) and zinc (Zn) with continuous ambulatory peritoneal dialysis, before and after desferrioxamine B (DFO) administration (2 g intravenously) in two patients with chronic renal failure and Al-related osteopathy. Both patients had 4 peritoneal dialysis exchanges (2 liters each) per day. Blood concentrations of Al increased 413% (patient A) and 190% (patient B) after DFO. Patient B had a 15% increase in Fe; other metals remained unchanged. Dialysate efflux Al concentrations had peak post-DFO increments of 761% and 840% in patients 1 and 2, respectively. Peak post-DFO increments in Fe dialysate concentration were 342% and 89.5% in the respective patients. Dialysate/plasma (D/P) concentration ratios of Al increased from pre-DFO levels (mean +/- SEM) of 0.370 +/- 0.048 to 0.523 +/- 0.061 after DFO; similarly, Fe D/P ratios increased from 0.259 +/- 0.053 to 0.446 +/- 0.075 with DFO therapy. These results indicate an increase in the ultrafiltrable proportion of Al and Fe in plasma after DFO administration. During 3 days after DFO, patient 1 had a total removal of Al and Fe of 2.9 mg and 4.9 mg, respectively. Metal removal in patient 2 was 7.6 mg of Al and 2.7 mg of Fe. Peritoneal extraction of other trace metals was minor.

Adult↗
PubMed1991

[Gammagraphy with sucralfate labelled with technetium in esophagitis].

In previous studies it has been reported that, after being labeled with technetium, sucralfate, an useful drug in peptic diseases, can be used to detect peptic lesions of the digestive tract. In this work we report our experience with this technique in the diagnosis of esophagitis. 25 studies (11 controls and 14 patients) were undertaken. Sucralfate scintigraphy was normal in the 11 control studies, and abnormal in 10 out of 14 patients. Scintigraphy was abnormal in peptic as well as caustic lesions.

Adult↗
PubMed1990

[A second drug in nonatopic asthma insufficiently controlled with beta 2-adrenergic stimulants: budesonide versus theophylline].

We assessed whether theophylline or budesonide (an inhaled corticosteroid) is the most adequate drug to be added to the treatment of patients insufficiently controlled with beta agonists (procaterol). Two comparable groups of nonatopic asthmatic adults (n = 24), aged between 16 and 66 years (42 +/- 17), were investigated in a crossed, randomized study. After 4 weeks with procaterol + 800 micrograms of budesonide, the forced expiratory flow improved (p less than 0.01), the degree of bronchial hyperreactivity to histamine was reduced (p less than 0.001), the daily recorded symptomatology almost disappeared in all and the number of procaterol inhalations was reduced (p less than 0.05). The combination of theophylline + procaterol during 4 weeks did not improve these parameters from their baseline values. It was concluded that inhaled steroids are the drugs of choice in patients with asthma which is not controlled only with beta agonists.

Adolescent↗
PubMed1990

Effects of fatty ethers and stearic acid on the gastrointestinal absorption of insulin.

Insulin degradation and inactivation occurs when the protein is given to an animal through oral route. The following compounds were assessed to determine their potential effect in increasing insulin absorption: polyoxyethylene (20) oleyl ether (Brij 99), polyoxyethylene lauryl ether and polyoxyethylene (20) cetyl ether (Brij 58). In this study the above compounds, along with stearic acid, were used to prepare granules with or without addition of insulin and were given orally to rabbits. Both glucose and insulin levels in blood were measured at different time intervals, the former with a glucometer and the latter using radioimmunoassay (RIA). To determine if there was a relationship between the glucose and the insulin levels in blood, a highly sensitive radioimmunoassay method was used to detect any small changes in the level of insulin in blood. A significant decrease in glucose blood levels (P less than 0.05) was obtained after oral administration of each of granules containing insulin. The greatest reduction was observed after half an hour of the oral administration of the granules. A similar response was obtained with the hypodermal injection of 1/5 of the oral insulin dose. Granules prepared with Brij 58 and containing insulin was the only formula that showed increase of insulin level in the blood. This was equivalent to 1/10 of the change produced after hypodermal injection of the hormone. In these experiments the changes in blood insulin levels were not directly proportional to the corresponding changes in blood glucose.

Animals↗
PubMed1990

[Achlorhydria, blood gastrin and normal gastric mucosa in high-altitude subjects].

According to current concepts, it is not feasible to associate achlorhydria with normal gastric mucosa. We have found in a group of high altitude dwellers, that it is possible to associate achlorhydria with normal gastric mucosa verified by endoscopic and histological studies. In this case, basal achlorhydria is associated with resistance to histamine stimulation and with high values of gastrinemia. The possibility of reduced parietal cell mass or the absence of gastrin and histamine receptors and of G-cell hyperfunction or hyperplasia, is discussed.

Achlorhydria↗
PubMed1990

Morphological studies of cytotoxic lesions in reversible endotoxic shock.

Reversible endotoxic shock was induced in adult rats by intravenous injection of E. coli 0111:B4 lipopolysaccharide (LPS) and the progression of metabolic and morphological alterations was evaluated. Serum samples and biopsies from adrenal gland, liver and lung were studied at different times after LPS injection. Histological changes in these tissues were observed after endotoxin administration, coinciding with both the acute-phase and the recovery-phase of shock (24-72h after LPS injection). Signs of tissue regeneration can be correlated with the regression of some serum parameters to their normal values. All these results indicate that in this experimental model of endotoxic shock, a reversible status was established, which will allow further studies of the endotoxic pathophysiological mechanisms in vivo, avoiding the complexity of the non-reversible process.

Adrenal Glands↗