Search PubMed⌕ Search

Biomedical subjects

F Ruiz

Publications and source records attributed to F Ruiz.

At least 91 records · Page 5Linked to original sources

The Ca2+ channel agonist Bay K 8644 induces central respiratory depression in cats, an effect blocked by naloxone.

We analyzed the respiratory effects induced by the Ca2+ channel agonist Bay K 8644 and its enantiomers, Bay R 5417 and Bay R 4407, applied to the ventral medullary surface of cats. Bay K 8644 (10 to 100 micrograms) and Bay R 5417 (50 to 200 micrograms) elicited a dose-dependent respiratory depression. Naloxone (0.1 mg/kg), but not D-naloxone, reversed these effects, indicating that an endogenous opioid mechanism was involved. Bay R 4407 (100 micrograms) was ineffective. The respiratory depressant effects induced by Bay K 8644 and its (-) enantiomer were a consequence of their agonist properties on the L-type Ca2+ channel, since (1) the activity of Bay K 8644 was stereospecific, and (2) nimodipine prevented the effect. We suggest that potent activation of Ca2+ channels or other mechanisms by high doses of Ca2+ agonists elicits the release of endogenous opioid peptides in medullary respiration-related structures.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗

Potentiation of acute opioid-induced respiratory depression and reversal of tolerance by the calcium antagonist nimodipine in awake rats.

The interaction between sufentanil, a mu-opioid agonist, and the Ca2+ antagonist nimodipine on respiration and on the development of opioid tolerance in awake rats has been analyzed. Our previous work demonstrated that chronic treatment with nimodipine together with sufentanil increases the analgesic potency of the opioid 50 fold. Therefore, we have investigated whether the opioid-induced respiratory depression is potentiated in parallel with the analgesia. Ventilation was measured by the whole body plethysmographic method. In naive rats, sufentanil (10-80 micrograms/kg) consistently induced a dose-dependent respiratory depression. Pretreatment with nimodipine (200 micrograms/kg) potentiated this effect but to a lesser extent than it potentiated analgesia. After chronic administration of the opioid (2 micrograms/h, 7 days) tolerance was manifested as a reduction in both the area under the time course curve and in the maximum effect. Nimodipine (1 microgram/h) administered concurrently with sufentanil for 7 days counteracted the tolerance to respiratory depression but no additional potentiation was observed. These results demonstrate that the interaction between nimodipine and sufentanil is not limited to antinociception but also extends to respiratory depression. However, compared with analgesia, the clinical relevance of a potential increase in opioid-induced respiratory depression by nimodipine may be negligible.

Animals↗

[Endoscopic resection of 49 polyps of the colon and rectum larger than 2 cm].

The management of rectal and colonic polyps has changed since the advent of endoscopic polypectomy, that interrupts the adenoma-carcinoma sequence. We assessed the effectiveness, limitations, morbidity and mortality of endoscopic polypectomy in 49 polyps larger than 2 cm in diameter. Polypectomy was successful in 94% of polyps, which were predominantly located in left colon (92%) and were pedunculated (87%). A malignant component was found in 28.3% of polyps, that was observed with higher frequency in larger and sessile polyps and in male patients. There was no mortality and scarce morbidity related to the procedure. It is concluded that polypectomy is a low risk procedure that can be frequently performed in ambulatory patients and that endoscopists must suspect malignancy in polyps larger than 2 cm in diameter.

Adolescent↗

[Visceral leishmaniasis and multiple organ failure].

BACKGROUND: Visceral leishmaniasis is a parasitic disease which has a good prognosis in previously healthy patients who have been successfully treated. At present, visceral leishmaniasis is increasingly reported in immunocompromised patients including those with AIDS, whose display a fulminating form and higher mortality. We report a case of visceral leishmaniasis in a healthy patient with a non classical clinical evolution of the disease. METHODS: A 17 years old patient without immunosuppressive factors was diagnosed by histologic evaluation of bone marrow which revealed intracellular leishmania amastigotes. Immediately the patient received treatment with antimony therapy. RESULTS: Patient developed a multi-organic failure (respiratory distress, disseminated intravascular coagulation, hepatic and renal insufficiency) and died at 13 days his after intensive care unit admission. CONCLUSIONS: The major new finding of this study is that in normal humans visceral leishmaniasis can have a dramatic short-term follow up in spite of correctly treatment. We suggest a possible immunological mechanism similar at non septic pathology.

Adolescent↗

Multiple sclerosis in Chile.

So far as we know this series of 68 cases is one of the first clinical accounts of multiple sclerosis in South America. Average age of onset was 30.7 years and female:male ratio was 2:1. The most frequent initial symptom was motor impairment and less frequent was visual loss. Most affected site of involvement in established cases was the optic nerve. There were no familial cases. The severity of the disease in Chile proved to be the same as elsewhere. No characteristic clinical pattern peculiar to the region emerged.

Chile↗

Temperature-dependent effects of morphine on the isolated right atrium.

The aim of the present study was to examine whether changes in temperature alter the effects of morphine on isolated right atria. Morphine dose-response curves at different temperatures (30, 37 or 40 degrees C) from right atria of the rat were obtained. The maximal negative chronotropic effect induced by morphine was 11 +/- 3% at 37 degrees C and 20 +/- 1% at 30 degrees C. However, when the temperature was increased to 40 degrees C, morphine induced a positive chronotropic effect. The increase in auricular automaticity induced by morphine at 40 degrees C was antagonized in the presence of naloxone (5 x 10(-6) mol/l). These data demonstrated that: (1) hyperthermia modifies the effects of morphine on isolated right atria and (2) at 40 degrees C morphine induces a positive chronotropic effect by activation of opioid receptors.

Animals↗

Progressive spastic paraparesis associated with human T-cell leukemia virus type I (HTLV-I).

Patients with progressive spastic paraparesis (PSP), commonly middle-aged women, are distributed throughout the country of Chile. During the three years from 1987 to 1990, we collected 83 cases of PSP from among 225 patients with various neurological diseases. The clinical picture was of a bilateral pyramidal syndrome, with sensory deficits in only 15.5% of the cases, and a slow illness progression in the majority of them. In patients with PSP, antibody to human T-cell leukemia virus type I (HTLV-I) was analyzed by enzyme linked immunosorbent assay (ELISA) and confirmed by western blot analysis. Forty-five (54.2%) patients were anti-HTLV-I antibody positive in cerebrospinal fluid (CSF) and peripheral blood. Among them, 2 patients had leukemia/lymphoma and one had Sjögren syndrome. In the laboratory study of seropositive PSP, mononuclear pleocytosis was found in 35.7%; there was an abnormal increase of the IgG index in 66.6% and an increase in CD2 in blood and CSF, and CD4 in blood. A delayed latency of somatosensory evoked potentials was observed in 90.9%. The neuropsychological study revealed a WAIS with a mean verbal IQ of 80.7 and a mean performance IQ of 84.8. The most impaired items were digit symbol and digit span. Seven subjects (18.9%) with anti-HTLV-I antibody were found among 37 relatives from 19 anti-HTLV-I positive cases of PSP.

Adult↗

[Respiratory complications in severe acute pancreatitis].

Respiratory complications are important causes of mortality in severe acute pancreatitis. We analyzed the pleuropulmonary complications that occurred in a series f 63 patients with severe acute pancreatitis. The most frequent were respiratory failure (52.4%) and bronchopulmonary infection (33.3%), both associated with sepsis and a high mortality rate. The initial laboratory workup included serial arterial blood gases and chest roentgenogram within the first 24 hours. The latter was useful to predict mortality. The tracheobronchial cultures isolated only enteral bacteriae. We conclude that pleuropulmonary complications are clearly related to the outcome of severe acute pancreatitis, specially when associated to sepsis.

Acute Disease↗

[Treatment of arterial hypertension with captopril in lupus nephropathy].

We present a non-controlled prospective study of 10 hypertensive patients with systemic erythematous lupus and nephropathy, treated with captopril exclusively or combined with other drugs, in order to assess its effectivity and potential side effects. Four of these 10 patients had mild hypertension; 3, moderate hypertension and 3, severe hypertension. In 5 of them, arterial pressures was controlled with just captopril; in other 3, we added furosemide and in one patient, we added furosemide and nifedipine. In one case, hypertension was not controlled. Renal function remained stable and proteinuria improved in six patients. Three patients presented reversible agranulocytosis, during or immediately after treatment. One of them was treated two years after with enalapril, without observing hematologic recurrence. We conclude that captopril is useful in treating arterial hypertension associated to lupous nephropathy, but frequent leukocyte counting controls must be done during the first months.

Adolescent↗

Ca2+ channel modulation by dihydropyridines modifies sufentanil-induced respiratory depression in cats.

We analyzed the interaction between sufentanil, a selective mu agonist, and two dihydropyridines, the Ca2+ antagonist, nimodipine, and the Ca2+ agonist, Bay K 8644, on the respiratory actions induced in the brainstem of cats. Drugs were applied topically to the ventral medullary surface. Sufentanil (0.26-26 nmol) consistently induced an immediate and dose-dependent reduction in tidal volume. Respiratory frequency was only depressed by the higher doses of the opiate. Pretreatment with nimodipine (0.19 and 0.38 mumol) potentiated the respiratory depression induced by sufentanil (0.26 nmol). The potentiation included both frequency and tidal volume. On the other hand, under the influence of Bay K 8644 (0.28 nmol), the respiratory effect of the opiate (7.8 nmol) was partially antagonized. Our results indicate that modulation of the L-type Ca2+ channels by dihydropyridines modifies sufentanil-induced respiratory depression at the controlling medullary mechanisms of breathing.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗

Cortical morphogenesis in Paramecium: a transcellular wave of protein phosphorylation involved in ciliary rootlet disassembly.

In Paramecium, the morphogenesis of the cortex at cell division, which assures reconstruction of shape and surface pattern, has been shown to involve transcellular signals which spread across the cortex like a wave, originating principally from the oral apparatus. One of the events these signals control is the reorganization of the ciliary rootlets through a cycle of regression and regrowth. The ciliary rootlets are nucleated on the ciliary basal bodies and form a scaffold extending over the entire cell surface that is important in aligning the basal bodies and the unit territories organized around them in longitudinal rows. We present evidence that the mechanism underlying their reorganization is cell-cycle-dependent phosphorylation of the structural proteins which compose the ciliary rootlets. We have isolated the rootlets and prepared a polyclonal antibody against them. In situ immunofluorescence of dividing cells with the anti rootlet antibody, and with the monoclonal antibody MPM-2 specific for phosphoproteins shows that a wave of phosphorylation of the ciliary rootlets spreads across the cell at division and just precedes their regression. Two-dimensional Western blot analysis of cytoskeleton and isolated rootlets along with alkaline phosphatase treatment demonstrates that the rootlets are composed of phosphoproteins, while experiments with interphase and dividing cells provide direct evidence that hyperphosphorylation of these proteins at division brings about disassembly of the structure.

Animals↗

Interaction between morphine and noradrenaline on isolated heart muscle.

1. We evaluated the interaction between morphine and noradrenaline on the right atria. 2. Noradrenaline significantly increased atrial contraction rate, with an effective concentration 16 (EC16) of 85 +/- 0.8 x 10(-9) M. 3. The EC16 of noradrenaline significantly decreased in the presence of morphine. 4. These results demonstrate that morphine increases the potency of noradrenaline on the isolated right atria.

Animals↗

Demoralization and gender differences in a kibbutz.

Gender differences in demoralization (depressive symptoms) were examined in a first-ever true prevalence study conducted in a kibbutz. The unusual organizational arrangements of this commune, where women have achieved higher levels of equality than in most other societies, offered a laboratory-like opportunity to test the psychosocial factors imputed as a partial explanation for the higher rates of demoralization in women. Demoralization was studied using the 27-item scale of the Psychiatric Epidemiology Research Interview (PERI) in all of the adult population of a single kibbutz. The response rate was close to 95%. Univariate and multivariate analyses were conducted to assess the effects of key sociodemographic and kibbutz-related variables on gender differences. The results showed that women had higher mean scores and rates even after these variables were controlled. The female:male demoralization ratio was well within the range of results obtained in non-socialist Israeli urban settings. The paper concludes with a discussion on the tentative relevance of the study results for the interpretation of the 2:1 female-male ratio of depression found in the epidemiological literature.

Adaptation, Psychological↗

[Acipimox in primary hyperlipidemias: safety and efficacy evaluated in six months].

The efficacy and tolerance of 750 mg of Acipimox was tested in 38 pts with primary dyslipidemias: 20 type IIa, 12 type IIb, and 6 type IV. All pts had been poor responders to a 2 month diet according to the recommendations of the National Cholesterol Education Program. Clinical examination, eye fundus, and the following laboratory tests: total cholesterol (TC), HDL, triglycerides (TG), total bilirubin, alkaline phosphatase, oxalacetic and pyruvic transaminases, uric acid, plasmatic creatinine, albumin, postprandial glucose test, hematocrit, white blood and platelet count were performed 60 days before drug initiation, 60 and 180 days after treatment had been started. No side effects were observed (myositis, visual gastrointestinal). 50% of the pts had slight to moderate flushing which appeared the first 3 days and lasted 14 +/- 7 days after treatment had been started. Plasmatic creatinine increased from 0.89 to 1.86 mg/dl in pt with one kidney, returning to normal levels 30 days after Acipimox interruption. After 180 days of therapy in the IIa group TC was -27% (p < 0.001), HDL + 15% (p < 0.001); in the IIb group: TC-23% (p < 0.001), HDL +9% (NS), TG -48% (p < 0.001); and in the IV group: TC-10% (p < 0.05), HDL +20% (p < 0.001), TG-53% (p < 0.001). Acipimox is well tolerated and is useful as a lipid-lowering drug in type IIa, IIb and IV dyslipidemias. Further studies are necessary to clear effects of the drug on renal metabolism and on long term survival of coronary pts.

Adolescent↗

The epidemiology of demoralization in a kibbutz.

This article reports a true prevalence study of demoralization conducted in a kibbutz. This commune, which assures its members all their instrumental needs throughout the individual life span, is probably one of the few of its kind in the world. All adult members (n = 353) of a kibbutz affiliated with the most orthodox of the federations replied to a self-administered interview containing the Psychiatric Epidemiology Research interview 27-item Demoralization Scale. The response rate approached 95%. Univariate and multivariate analyses were conducted using demoralization rates and mean scores as dependent variables. The overall prevalence of demoralization was 25%. Women exhibited higher rates and mean scores. There was a clear association between occupational prestige scores and demoralization in both sexes. Discussion is based on the comparison between the study findings and those published in the literature, both in terms of the overall results and their pattern of association with key sociodemographic variables.

Adult↗