Biomedical subjects

J Rojas

Publications and source records attributed to J Rojas.

At least 55 records · Page 3Linked to original sources

PubMed1998

[Biopsy and endoscopic prospective study of the prevalence of intestinal metaplasia in the gastroesophageal junction in controls and in patients with gastroesophageal reflux].

BACKGROUND: The classic diagnosis of Barret esophagus is based on the finding of three of more cm of distal esophagus covered by specialized columnar epithelium. However, at the present time, it is based on the presence of intestinal metaplasia in the junction of squamous-columnar mucosae. AIM: To assess the prevalence of Barret esophagus using endoscopic and pathological criteria in healthy subjects and in individuals with gastroesophageal reflux. PATIENTS AND METHODS: One hundred thirty nine controls and 372 patients with symptoms of gastroesophageal reflux subjected to an upper gastrointestinal endoscopy were studied. Patients with Barret esophagus were classified as having a "mini Barret" when the pathological presence of intestinal metaplasia was the only finding. A "short Barret esophagus" was diagnosed when less than 3 cm were covered with fingerings of mucosal substitutions and "extensive Barret esophagus" when more than 3 cm of esophageal mucosa were substituted. RESULTS: Two percent of controls, 12.4% of patients with gastroesophageal reflux without esophagitis and 11.7% of such patients with esophagitis had intestinal metaplasia in the gastroesophageal junction. Patients with Barret esophagus were older than the rest of patients. "Short Barret esophagus" is six times more frequent than "extensive Barret esophagus". Esophageal erosions, peptic ulcers and stenosis were more frequent in patients with extensive Barret esophagus. The prevalence of dysplasia was similar in all types of Barret esophagus. CONCLUSIONS: Intestinal metaplasia was very infrequent in control patients. In subjects with gastroesophageal reflux, classic endoscopic diagnosis may miss up to 80% of patients with Barret esophagus. Thus, gastroesophageal junction biopsies must be obtained in all patients with symptoms of gastroesophageal reflux.

Adolescent↗

PubMed1998

Fasciola hepatica: partial characterization of circulating antigens.

Antigens present in sera from Fasciola hepatica-infected goats were partially characterized by means of polyacrylamide gel electrophoresis of immunoprecipitates obtained by counterimmunoelectrophoresis. Agar containing the 2 immunoprecipitin lines, agar containing no precipitin lines, a crude extract of F. hepatica, and normal rabbit IgG were assayed. The electrophoretic pattern of 1 precipitin line showed, apart from the light and heavy chains of IgG and other faint bands, 2 prominent polypeptides of about 70 and 85 kDa. The other precipitin line showed a similar pattern, but with the 70-kDa band absent.

Animals↗

PubMed1998

[Clinical and laboratory characteristics of patients with pathologic chronic gastroesophageal reflux].

BACKGROUND: Sixty percent of adults has typical symptoms of gastroesophageal reflux in Chile. AIM: To report the clinical and laboratory features of patients with gastroesophageal reflux. PATIENTS AND METHODS: Five hundred thirty-four patients (255 male) with gastroesophageal reflux were included in a prospective protocol that included clinical analysis, manometry and endoscopy in all patients, barium swallow in 427, scintigraphy in 195, acid reflux test in 359, 24 h pH in 175, and differential potential of gastroesophageal mucosa in 73 patients. RESULTS: There was no correlation between the severity of symptoms and the endoscopical severity. Patients with Barret esophagus were 12 years older, were male in a greater proportion and had a higher proportion of manometrically incompetent sphincters than patients with esophageal reflux but without esophagitis or with erosive esophagitis. Severity of acid reflux, measured with 24 h pH monitoring was proportional to the endoscopical damage of the mucosa. There was a close relationship between the mucosal change limit determined with differential potentials and with endoscopy. No short esophagi were found. CONCLUSIONS: Patients with symptoms of gastroesophageal reflux must be assessed using several objective measures to determine the severity of their pathological alterations.

Adult↗

PubMed1997

Multimodal therapy for children and adolescents with Ewing sarcoma: results of the First National Chilean Trial (1986-1991).

Thirty-seven patients with Ewing sarcoma were treated in the First National Chilean Trial for Ewing's Sarcoma (1986-1991), which comprised the St. Jude Ewing's 78 Study. All patients received cyclophosphamide, doxorubicin, vincristine, and Dactinomycin for a total treatment period of about 10 months, and all prescribed therapy was administered. Local therapy consisted of irradiation (RT) to the primary tumor, complete surgical resection, or a combination of both surgery and RT. Twenty-nine of these patients had localized tumors, 24% had pelvic primary tumors, 21 were males, and 20 were greater than 10 years of age at diagnosis. Twenty-one patients had tumors that were greater than 8 cm in largest diameter. Fourteen of the 29 patients with localized disease remain disease free at 23 to 91 months from diagnosis. Fourteen patients have died of-tumor-related complications and 1 of a secondary malignancy. Relapse was local only in 4, metastatic in 9, and local plus metastatic in 1. Only 1 of the 8 patients with metastatic disease at presentation remains disease free. Toxicity consisted primarily of myelosuppression and mucositis. We conclude that this form of relative intense multimodal therapy for children/adolescents with localized Ewing sarcoma is curative in about half of affected children as in the original St. Jude study, and that it can be safely given in a developing country, provided that careful attention to supportive care and treatment planning is given. Although these results represent improvement in outcome for our patients, more effective therapy is needed for children with Ewing sarcoma, especially those with metastatic disease at presentation.

Adolescent↗

PubMed1997

Immunological characteristics and localization of the Trichinella spiralis glutathione S-transferase.

Trichinella spiralis glutathione S-transferase (TsGST) was isolated from crude extracts of L1 larvae by glutathione-affinity chromatography. Two closely migrating polypeptides with molecular masses of 28.5 and 28 kDa were identified by electrophoresis. Three isoforms of pI 5.6, 5.8, and 6.0 were detected by isoelectric focusing. Purified TsGST showed a low transferase activity as measured with 1-chloro-2,4-dinitrobenzene; glutathione peroxidase activity was also demonstrated using cumene hydroperoxide. A rabbit antiserum against TsGST reacted by western blot with crude extracts of Trichinella britovi and Trichinella nativa but not with extracts of Trichinella pseudospiralis, Fasciola hepatica, Schistosoma bovis, Schistosoma mansoni, Dirofilaria immitis, Toxocara canis, or Anisakis sp. TsGST was detected by western blot in extracts of T. spiralis adults, but not in newborn larvae or L1 excretory-secretory products; yet, an antiserum against T. spiralis excretory-secretory products reacted with TsGST. By immunoelectron microscopy, TsGST was found in the granules of the alpha- and beta-stichocytes of L1 larvae, as well as in some granules of the stichocytes of 72-hr adults. Rabbits experimentally infected with T. spiralis developed substantial levels of anti-TsGST antibodies. Moreover, circulating TsGST was detected in serum by a sandwich-enzyme-linked immunosorbent assay, isolated from serum by glutathione-affinity chromatography, and characterized as TsGST by western blot.

Animals↗

PubMed1996

Labelling of haptenic drug with digoxigenin for competitive immunoassay: its application to lesopitron, a new anxiolytic agent.

A new labelling approach of haptenic drugs with digoxigenin for the development of competitive enzyme immunoassay (EIA) is reported. It consists of the covalent linking of the hapten to the preactivated digoxigenin derivative and revealing the immune complexes with anti-digoxigenin Fab fragments coupled to alkaline phosphatase. This approach has been applied to the development of an EIA for the pharmacokinetic study of lesopitron (E-4424), a new anxiolytic agent. The assay involves a solid-phase immobilization of IgG purified from polyclonal antiserum developed against the butylamino derivative of lesopitron covalently linked to bovine serum albumin. The tracer consists of the covalent linking of the same butylamino derivative to digoxigenin-3-O-methylcarbonyl-epsilon-aminocaproic acid N-hydroxysuccinimide ester. The calibration curve for E-4424 from 12.5 to 6400 pg per well displays an ED50 of 34.5 pg per well, a slope factor of 0.86 and a minimum detectable dose of 4.1 pg per well. The accuracy and the precision of the assay assessed at three different concentrations of E-4424 (500, 1000 and 2000 pg ml-1) give a recovery higher than 95% and intra- and inter-assay RSDs lower than 5 and 10%, respectively. The specificity of the assay was demonstrated by a good correlation of the samples analysed by both HPLC and EIA. A kinetic profile of E-4424 in rats following an oral dose of 50 mg kg-1 has also been established.

Animals↗

PubMed1996

Evaluation of gingival and periodontal conditions following causal periodontal treatment in patients treated with nifedipine and diltiazem.

It is established that phenytoin, cyclosporin and some calcium antagonists produce gingival overgrowth, but it is not known how this condition may respond to causal periodontal treatment. In order to find out, a longitudinal study was carried out, over a year, comparing a group of patients who were given nifedipine (NG, n = 18) and another group who were given diltiazem (DG, n = 13) with 2 others: one comprised cardiopathic patients who took no calcium antagonists (CG, n = 12) and the other contained patients who were medically healthy, with moderate periodontitis (HG, n = 12). On their basal visit, they were examined and instructed in oral hygiene, and then given causal periodontal treatment, being seen again at 4 and 8 months, when hygiene instructions were reinforced. They were seen for the last time at 12 months, when they were again examined. Groups NG and DG, on their basal visit, showed larger gum size than groups HG and CG, which was statistically significant; on their final visit, these differences remained only at the interproximal level. The number of patients with gingival overgrowth-taking the average of group HG as a minimal value-was much higher in groups CG (92%), DG (100%) and NG (89%) on the basal visit; on the final visit, the differences remained only in groups DG (85%) and NG (83%). The probing pocket depth reduction was much greater in groups HG and CG than in DG and NG, basically due to a greater gaining on clinical attachment level. The % of sites in which the pocket depth improved by more than 2 mm was 39.8% in HG, 54.5% in CG, 23.7% in DG and 28.7% in NG. The % of sites where the attachment gain by more than 2 mm was 46.2% in HG, 55.5% in CG, 22.8% in DG and 21.4% in NG. The amount of plaque and bleeding on probing, which was similar in all groups on the basal visit, decreased throughout the study, especially between the basal and 2nd visit in groups HG and CG. We have demonstrated that patients that take nifedipine and diltiazem show a larger gum size and their response to causal periodontal treatment is poorer than in the healthy and the cardiac groups.

Analysis of Variance↗

PubMed1996

[A new classification of lower infarcts with important prognostic significance].

BACKGROUND: The initial therapy of acute myocardial infarction is often determined by the electrocardiogram. OBJECTIVE: To evaluate a classification of inferior myocardial infarctions according to the first electrocardiogram. DESIGN AND SETTING: Prospective study in a coronary care unit. PATIENTS: 116 patients admitted due to a first acute myocardial infarction of the inferior wall. METHODS: "Type 1" electrocardiogram was defined as ST segment elevation without distortion of the QRS. Patients were considered "type 2" when, besides ST segment elevation, they presented a distortion of the terminal portion of the QRS complex in two inferior leads. MAIN RESULTS: Twenty-nine patients (25%) were considered "type 2". These patients were older and had worse Killip class than "type 1". The mortality rate was 1.2% in "type 1", and 24.1% in "type 2" (p = 0.0002). After multivariate analysis, which included Killip class, age, smoking, type of electrocardiogram and fibrinolysis, the type of electrocardiogram remained significantly predictive of death (p = 0.014). CONCLUSIONS: We conclude that "type 2" electrocardiogram is an independent predictor of adverse outcome in inferior infarctions. Further investigation is needed concerning its implications in the clinical management of these patients, although reperfusion therapy is warranted.

Adult↗

PubMed1995

Clinical assessment of gingival size among patients treated with diltiazem.

Gingival overgrowth induced by nifedipine has been extensively reported. This finding, however, does not apply to gingival size changes caused by other calcium antagonists such as diltiazem. We studied the gingiva of 13 subjects with ischemic cardiopathy who had been treated with diltiazem and established two control groups: (1) a healthy group of 12 patients and (2) a group of 10 patients with ischemic cardiopathy and concomitant treatment similar to that applied to the diltiazem group except that they had not been administered any type of calcium antagonists. The size of the gingiva around the six anterior teeth was measured on plaster models of the upper and lower jaws. Significantly higher scores of the size of the gingiva were found when patients treated with diltiazem were compared with the patients in the other two groups (p < 0.05) gingiva were found when patients treated with diltiazem were compared with the patients in the other two groups (p < 0.05) and also when interproximal (p < 0.05) and vestibular (p < 0.05) sites were considered. We did not observe any significant difference in the plaque index of each group (p < 0.05); only bleeding after probing was found statistically different between the diltiazem and the nondiltiazem groups.

Adult↗

PubMed1995

[Age is the independent prognostic factor in acute myocardial infarct. The clinical course of infarct in the elderly patient].

We analyze the influence of age in the evolution of patients with acute myocardial infarction admitted to our Coronary Care Unit throughout two years (1990 and 1991). All 542 patients admitted during this period were classified in three groups: 299 less than 65 year old (group A), 170 between 65 and 74 year old (group B), and 73 with 75 year old or more (group C). Aged patients had a worse clinical condition, with significantly more previous heart failure, diabetes or hypertension, and the Killip's class was worse in group C than in group B, and worse in this than in group A (p = 0.00000). The mortality rate was 6.7% in group A, 12.9% in group B, and 31.5% group C (p = 0.00000). After a multivariate analysis, only three factors were significantly associated to prognosis: previous stroke, Killip's class, and group of age. Fibrinolytic therapy and coronary arteriography were less frequent with old people (p = 0.00000 and p = 0.00000 respectively). We conclude that age is an independent factor of prognosis during myocardial infarction. Old people have a worse clinical condition and the treatment is less aggressive than in young people.

Age Factors↗

PubMed1995

[The prognosis for elderly patients admitted to a coronary unit for myocardial infarct: the changes over a decade].

INTRODUCTION AND AIM: New therapies have been added that improve prognosis of patients with myocardial infarction. Our purpose was to know if elderly patients reach benefit from these therapeutic changes. METHODS: We have analyzed the clinical data of 227 patients older than 70 who were admitted in our coronary care unit: 78 admitted in 1980-81 and 14 admitted in 1990-91. RESULTS: Although differences were not significant, in 1990-91 there were more women (36% versus 28%), less smoking (24% versus 33%), more patients with previous infarction (19% versus 12%), more hypertension (53% versus 43%), less anterior infarcts (38% versus 45%) more non Q infarcts (11% versus 1%), and less bundle branch block (21% versus 31%). In 1990-91, pacemakers were used less often (13% versus 27%, p = 0.03), thrombolytic therapy was given to 16 patients (10.7%), and the mortality rate was a little inferior (22% versus 30%, not significant). Female sex, not being a smoker, Killip class and bundle branch block were significantly related to mortality. After a multivariate analysis in which these factors we included, the date of admission resulted an independent predictor of mortality, with an odds ratio of 1990-91 to 1980-81 of 0.43 (p = 0.039). CONCLUSIONS: The management of patients older than 70 with myocardial infarction has improved, with a significantly lesser risk of dead after multivariate analysis, despite that thrombolysis has been scarcely applied.

Aged↗

PubMed1994

Clinical assessment of gingival hyperplasia in patients treated with nifedipine.

Gingival hyperplasia caused by the use of nifedipine has been extensively reported. In this paper, the gingiva of 18 patients suffering from cardiopathy and treated with nifedipine were compared with those of 10 patients with cardiac disorders who had not been treated with calcium antagonists and with a no-treatment group of 12 patients. Nifedipine produced gingival hyperplasia, although patients who had not been treated with calcium antagonists also had mild hyperplasia. Hyperplasia first appeared in the interproximal areas, an observation which may be important for early detection. There was a direct correlation between the degree of hyperplasia and the bacterial plaque score. When we studied the influence of administration time and dose of nifedipine with the degree of hyperplasia, no statistically significant differences were found.

Dental Plaque Index↗

PubMed1992

Chemotaxis of Leptospirillum ferrooxidans and other acidophilic chemolithotrophs: comparison with the Escherichia coli chemosensory system.

Ni2+, Fe2+ and Cu2+ were attractants and aspartate was an apparent repellent for Leptospirillum ferrooxidans, a behaviour opposite to that for Escherichia coli. Membranes from L. ferrooxidans contained proteins with a molecular mass in the range of 80 kDa which were methylated in vitro. Methylation was stimulated in the presence of a membrane-free extract from E. coli, showing the response pattern expected for L. ferrooxidans, increased methylation by Ni2+, and demethylation by aspartate. This suggests the existence of sensory transducers having a common methylation domain with the E. coli methyl-accepting chemotaxis proteins. Total chromosomal DNA digests from L. ferrooxidans, Thiobacillus ferrooxidans and T. thiooxidans hybridized with probes containing different domains of the tar gene from E. coli, implying the presence of tar type genes in the acidophilic bacteria studied.

Bacterial Proteins↗

PubMed1992

Inhibitory effect of opiates on male rat sexual behavior may be mediated by opiate receptors outside the central nervous system.

The importance of opiate receptors outside the central nervous system for the inhibitory actions of morphine on male rat sexual behavior was evaluated. Morphine (10 mg/kg) produced an almost complete inhibition of sexual behavior. This inhibition was antagonized by naloxone at a dose of 1 mg/kg but not at a dose of 0.25 mg/kg. The quaternary opioid antagonist methylnaloxone effectively blocked the inhibitory actions of morphine at a dose of 20 mg/kg but not at a dose of 5 mg/kg. Since the affinity of methylnaloxone for opiate receptors is about 5% of that of naloxone, it may be concluded that both antagonists were about equally effective in inhibiting the effects of morphine. Furthermore, the opiate-like drug loperamide was found to inhibit sexual behavior. This drug acts mainly outside the central nervous system. Its effect was blocked by both naloxone and methylnaloxone, suggesting that opiate receptors are involved. It was also shown that methylnaloxone is unable to block the reinforcing effects of morphine in the conditioned place preference procedure. Because the reinforcing effects of opiates seem to be localized to the central nervous system, it may be proposed that methylnaloxone does not antagonize morphine's central effects. Moreover, loperamide had no effect in the place preference procedure, suggesting that this drug does not act at central opioid receptors. Taken together, these data show that peripheral opioid receptors are responsible for at least some of the inhibitory actions of morphine on male sexual behavior. After treatment with morphine + methylnaloxone, ejaculatory mechanisms were facilitated, reflected in a reduced number of preejaculatory intromissions and a shortened ejaculation latency.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗

PubMed1991

Thrombolytic therapy soon after left heart catheterization--is it safe?

Puncture of a femoral artery for left heart catheterization is considered a relative contraindication for thrombolytic therapy for some days. We treated 9 patients with systemic thrombolysis who had undergone left heart catheterization in the previous hours. Four patients developed a large hematoma, but only 1 required transfusion. We suggest that thrombolytic therapy can be administered soon after left heart catheterization by the femoral approach, provided that continuous care can be taken over the puncture site.

Adult↗

PubMed1991

Liposome-entrapped ampicillin in the treatment of experimental murine listeriosis and salmonellosis.

The tissue distribution of ampicillin entrapped in liposomes was studied in normal noninfected mice and showed that ampicillin concentrated mostly in the liver and spleen. Liposomate ampicillin was significantly more effective than free ampicillin in reducing splenic and hepatic bacterial counts in C57BL/Ka nude mice chronically infected with Listeria monocytogenes EGD. It was also significantly more effective than free ampicillin in reducing mortality in C57BL/6 mice acutely infected with Salmonella typhimurium C5. Comparison of the results with those previously obtained in the same experimental models with the same amounts of ampicillin bound to polyisohexylcyanoacrylate nanoparticles showed that liposomes were more effective than nanoparticles (M. Youssef, E. Fattal, M. J. Alonso, L. Roblot-Treupel, J. Sauzières, C. Tancrède, A. Omnès, P. Couvreur, and A. Andremont, Antimicrob. Agents Chemother. 32:1204-1207, 1988) in targeting ampicillin to the spleen but were less effective than nanoparticles in targeting ampicillin to the liver and reducing mortality in acute salmonellosis.

Ampicillin↗

PubMed1990

Action of baclofen, GABA and antagonists on the membrane potential of cultured astrocytes of rat spinal cord.

The action of gamma-aminobutyric acid A (GABAA) and B (GABAB)-agonists has been studied on the membrane potential of astrocytes in explant cultures of rat spinal cord by means of intracellular microelectrode recordings. The GABAB-agonists (-)-baclofen and CGP 27 492 (3-aminopropyl phosphonous acid; 10(-6) to 10(-4) M) caused a hyperpolarization of the majority of astrocytes studied. On approximately 25% of the cells, the compounds had no effect. The hyperpolarization by baclofen (10(-4) M) was reversibly antagonized by the GABAB-antagonist 5-hydroxysaclofen (10(-4) M). GABA and the GABAA-agonist muscimol (10(-4) and 10(-3) M) depolarized approximately two thirds of the glial cells tested, whereas the remaining third remained unaffected. The GABAA-antagonist bicuculline (10(-4) and 10(-3) M) only reduced the depolarization by GABA (10(-4) M) but did not completely block it. On half of the cells tested, the depolarization by GABA was not affected by bicuculline, suggesting that the glial GABAA-receptor is different from the neuronal GABAA-receptor. Our electrophysiological investigations together with recent autoradiographic binding studies strongly suggest the existence of GABAB-receptors on astrocytes whereas there is less evidence for GABAA-sites on these cells.

Animals↗

PubMed1990

Blood gas transport properties in endurance-trained athletes living at different altitudes.

Hemoglobin oxygen binding properties and acid-base status were investigated in Colombian athletes (A) and controls (C) from Cali (C-1000 m) and Bogotá (B-2600 m). [Hb] and Hct values were not influenced by altitude, but Hct was lower in the blood of athletes (in Cali 2.6%, in Bogotá 1.4%). Both training and altitude produced a right-shift of the standard oxygen dissociation curve (P50 in CC 28.5 +/- 0.9 mmHg, AC 31.0 +/- 1.4 mmHg, CB 29.6 +/- 1.5 mmHg) leading to highest P50 in blood of altitude athletes (32.3 +/- 1.1 mmHg). Opposite to the position of the ODC the slope "n" was only increased by altitude influence (delta "n" in controls 0.07, in athletes 0.28). The BCCO2 was increased in AC over the whole saturation range, whereas BCLac was neither significantly influenced by training nor by altitude. All altitude effects can be explained by higher [DPG] (delta[DPG] in controls 5.0 mumol/gHb, in athletes 3.9 mumol/gHb), but the cause for the training effects still remains unclear. The acid base status in altitude residents was characterized by low BE and pCO2, which was most pronounced in altitude athletes, the latter correcting the actual venous pH to normal values. No significant variations of the Hb-O2-binding properties could be detected in athletes one day after leaving high altitude when compared with blood samples of athletes taken at high altitude, whereas BE and venous pCO2 were already increased. It is concluded that high altitude athletes are favoured during aerobic and handicapped during anaerobic exercise after the rapid descent to low altitude.

Acid-Base Equilibrium↗