Biomedical subjects

M Rojas

Publications and source records attributed to M Rojas.

At least 109 records · Page 6Linked to original sources

PubMed1994

[Images of pancreatic pathology: advantages and limitations of magnetic resonance compared with computerized tomography and ultrasound].

We discuss the usefulness of MR examination in the diagnosis of pancreatic diseases, in addition to the other available imaging techniques. MR imaging yields important information in diagnosis and staging of pancreatic tumours, and in the characterization of pancreatic masses. MRI is also valuable for the study of chronic as well as acute pancreatitis, although there are some limits such as the poor detection of calcifications in the chronic, and the excessively long time required to complete the examination in the acute form.

Adenocarcinoma↗

PubMed1993

Vaccination with SPf66, a chemically synthesised vaccine, against Plasmodium falciparum malaria in Colombia.

Preclinical and clinical studies have established the safety and immunogenicity of the chemically synthesised SPf66 malaria vaccine. The present study is a phase III randomised, double-blind, placebo-controlled, efficacy trial completed in La Tola, Colombia. 1548 volunteers over one year of age received three doses of either the vaccine (n = 738) or placebo (n = 810). Active and passive case detection methods were used to document clinical episodes of malaria among the study population. The follow-up period began one month after the third dose and lasted for one year. 168 and 297 episodes of Plasmodium falciparum malaria were documented in the SPf66 group and the placebo group, respectively; this corresponds to a crude protective efficacy of 38.8%. Incidence rates for first or only P falciparum malarial episodes were 22.3% per annum among the vaccinee group and 33.5% among the placebo group (RR = 1.5; 95% Cl 1.23, 1.84). Therefore, the protective efficacy of SPf66 against first or only episodes was 33.6% (95% Cl 18.8, 45.7), being highest in children aged 1-4 years (77%) and adults older than 45 years (67%). The estimated protective efficacy against second episodes was 50.5% (95% Cl 12.9-71.9). Our study shows that the chemically synthesised SPf66 malaria vaccine is safe, immunogenic, and protective against P falciparum malaria in semi-immune populations subject to natural challenge.

Adolescent↗

PubMed1993

Elevated levels of antibodies against sulphatide are present in all chronic chagasic and dilated cardiomyopathy sera.

A natural anti-sulphatide antibody was found to be present in the serum of every normal individual studied. The reactivity of the antibody was assessed by its interaction with galactosylceramide-I3-sulphate. Antigen-antibody binding was strongly blocked by 1 mM heparin, dextran sulphate and chondroitin sulphate A, and by 5 mM chondroitin sulphate B. Antibodies avidly absorb to rabbit erythrocytes, but discretely to rat erythrocytes, suggesting that they are different from galactocerebroside antibodies. Elevated levels of sulphatide antibodies were present in all of 102 chronic Trypanosoma cruzi-infected patients studied, but not in other patients having cutaneous or visceral leishmaniasis, T. rangeli infection or several other protozoal, helminthic or mycotic infections. Interestingly, 100% of 40 dilated cardiomyopathy patients also have elevated levels of sulphatide antibodies. As T. cruzi is rich in galactocerebroside sulphate, it is proposed that in chagasic patients this glycolipid could act as an immunogen, inducing elevated titres of sulphatide antibodies, which could be important in the pathogenesis of cardiac or peripheral nerve symptoms.

Adolescent↗

PubMed1993

An epidemiological study of disorders in late childhood and adolescence--I. Age- and gender-specific prevalence.

Developmental aspects of psychiatric disorders may be inferred from patterns of age differences in prevalence. Age-specific prevalences are provided for nine disorders in a general population sample of ages 10-20. Age and gender patterns for several disorders suggest developmental stage-associated risks. These include oppositional disorder in both genders and conduct disorder and major depression in girls. Major depression shows a pattern suggestive of a role for the onset of puberty. The prevalence of one or more disorders did not differ by age or gender. However, the pattern of specific diagnoses varied greatly by both age and gender.

Adolescent↗

PubMed1993

[Gyneco-obstetric aspects in women developing postpartum depression].

The relationship between different variables was studied related to pregnancy, labor, puerperium, newborn and breast-feeding with the development of a depressive disorders during pregnancy, in a sample of 125 pregnant women. No relationship it's found with the presence of disease during the gestation period, except urinary tract infection. The same happens with other variable of labor, puerperium and newborn, Nevertheless, the major stress situations (urgent cesarean section, use of anesthesia during labor, diseases of the newborn, etc.) systematically present a higher incidence of depression. It is observer a relationship between the development of a depressive disorders and a decrease of the natural lactation period.

Adolescent↗

PubMed1993

[Cardiac manifestations of phospholipid antibody syndrome. Study of 2 cases].

Cardiac manifestations of phospholipid antibody syndrome may include mitral and/or aortic valve disease, pseudo-infectious endocarditis, thrombi of the right atrium, myocardial infection, pulmonary artery hypertension and cardiomyopathy with global or segmental left ventricular dysfunction. The authors report two patients showing evidence simultaneously of a circulating anticoagulant, dissociated syphilis serology and cardiolipin antibodies at a very high level. They had the majority of cardiac complications described in phospholipid antibody syndrome. Both also had renal involvement and one of them had recurrent venous thromboses and a cerebrovascular accident. Prolonged corticosteroid treatment, combined with anticoagulants in one patient, was accompanied by stability of lesions with follow-up of five years and ten months respectively.

Adult↗

PubMed1993

[Depressive disorders during pregnancy and associated factors].

A group of 125 pregnant women is studied that is under the control of 2 urban and 1 rural health clinic, were it was found an incidence of 29% of depressive disorders. It is observed that three aspects are strongly related with this disorders: unwanted pregnancy, unsatisfactory couple relationships and personal back-ground with depression. A working model is proposed that seeks to comprehend this phenomenon in its entirety.

Adolescent↗

PubMed1993

[The role of magnetic resonance in the evaluation of pathological processes involving the penis].

The above paper was aimed at defining the usefulness of MRI in the study of pathologies involving the penis. Disorders considered include Peyronie's disease, fibrosis of the penis, priapism, trauma, congenital anomalies, and tumors. In Peyronie's disease and in fibrosis of the penis, MRI permits to demonstrate the abnormal thickening of tunica albuginea and erectile tissue; after administration of gadolinium, it becomes possible in some cases to demonstrate plaques of the albuginea that are not palpable. In priapism, MRI is useful both for identifying the cause and for assessing the time elapsed since blood extravasation. In traumatic and congenital pathologies, MRI is essential for the acquisition of all information on anatomy that may be useful for selecting the most suitable surgical therapy. In neoplastic pathology, MRI has proved useful for accurately assessing the extension of lesions involving the basis of the penis.

Diagnosis, Differential↗

PubMed1993

Analysis of DNA adducts in smokers' lung and urothelium by 32P-postlabelling: metabolic phenotype dependence and comparisons with other exposure markers.

Carcinogen-DNA adduct levels in lung parenchyma (surgical specimens) and urothelial (exfoliated) cells of smokers, ex-smokers and non-smokers were investigated. DNA adducts were analysed by 32P-postlabelling and levels were compared with tissue-specific activity of cytochrome P450-related enzymes, or whenever possible, with metabolic phenotypes and other macromolecular adducts. Lung cancer patients who were recent smokers had significantly induced benzo[a]pyrene (BaP)-3-hydroxylase (AHH) and ethoxycoumarin O-deethylase activities in lung parenchyma compared with smoking non-cancer patients. Pulmonary AHH activity showed a good correlation with the intensity of immunohistochemical staining for P4501A(1). In lung cancer patients from Italy and Finland who were recent smokers, lung AHH activity was positively correlated (r approximately 0.65; p < 0.001) with bulky DNA adduct levels. In some lung DNA samples from smokers, the level of BaP-diol-epoxide adducts determined by HPLC with fluorescence detection showed significant positive correlation with lung AHH activity and bulky DNA adduct levels. Molecular dosimetry studies provided evidence that aromatic amines such as 4-aminobiphenyl (ABP) in tobacco smoke are primarily responsible for bladder cancer in smokers. The N-(deoxyguanosin-8-yl)-4-ABP adduct was the major smoking-related adduct in DNA of bladder biopsies from bladder cancer patients and in the DNA of exfoliated urothelial cells of smoking volunteers. The adduct levels of ABP with haemoglobin and with deoxyguanosine in urothelial DNA (determined by 32P-postlabelling) were linearly and significantly correlated, and both were related to recent cigarette smoking. Metabolic phenotype (fast/slow N-acetylator and N-oxidizer) significantly affected the levels of ABP-haemoglobin adducts.

Aryl Hydrocarbon Hydroxylases↗

PubMed1993

[Comparative study of famotidine vs ranitidine in critically ill patients in mechanical ventilation].

Stress ulcers are frequent in critically ill patients. Gastric mucosa protection with antacids, H2 blockers or sucralphate decrease the incidence of stress ulcers and upper gastrointestinal bleeding but may have adverse effects. The present study compares the efficacy of continuous infusions of famotidine on gastric pH control and bleeding prevention in critically ill patients receiving mechanical ventilation. Fifty six patients (aged 55 +/- 22 years, 26 male) were randomly assigned to receive famotidine 40 mg/day (n = 27) or ranitidine 150 mg/day (n = 29) during 5 days. Gastric pH was measured every 6 hours and when it was below 5, aluminum hydroxide (30 ml every 2 hours) was administered to obtain values over 5. Patients receiving famotidine had higher mean gastric pH (6.3 +/- 0.2 and 93% of measurements over 5 vs 5.8 +/- 0.6 and 83% of measurements over 5 (p < 0.05), and required lower amounts of aluminum hydroxide (1.880 vs 2.770 ml). No patient had evidence of gastrointestinal bleeding and one had a mild psychomotor agitation. No other adverse reactions were observed. It is concluded that famotidine was more effective than ranitidine on gastric pH control in mechanically ventilated critically ill patients.

Acute Disease↗

PubMed1993

[Comparison of magnetic resonance and other imaging methods in the diagnosis of diseases of the seminal vesicles].

The aim of this work was to evaluate the usefulness of MR imaging in the diagnostic study of seminal vesicles and to emphasize the relationships between this technique, CT scan and trans-rectal ultrasonography (TR-US). We discussed pathological findings due to congenital anomalies, phlogistic or neoplastic lesions and iatrogenic changes of normal tissues. MR imaging and TR-US seem to be the most reliable techniques for typing pathological tissues and for grading the extension of neoplatic masses arising from bladder, prostate, and rectum, involving seminal vesicles.

Diagnostic Imaging↗

PubMed1992

An improved fluorometric assay for dosimetry of benzo(a)pyrene diol-epoxide-DNA adducts in smokers' lung: comparisons with total bulky adducts and aryl hydrocarbon hydroxylase activity.

An improved high-performance liquid chromatography/fluorometric assay has been established to quantitate the benzo(a)pyrene (BP) tetrols released after acid hydrolysis of lung DNA from lung cancer patients, so that the formation of benzo(a)pyrene diol-epoxide-DNA adducts can be measured. The r-7,c-10,t-8,t-9-tetrahydroxy-7,8,9,10-tetrahydro-BP isolated by high-performance liquid chromatography was determined by chromatography in two different solvent systems and fluorescence spectroscopy. This assay has a detection limit of 2 pg of r-7,c-10,t-8,t-9-tetrahydroxy- 7,8,9,10-tetrahydro-BP, requires 100-500 micrograms of DNA, and can measure 1 adduct/10(8) unmodified nucleotides. As this assay does not use immunoaffinity chromatography or solvent extraction, it allows a > 90% recovery of benzo(a)pyrene diol-epoxide-DNA adducts. This procedure has been tested on 13 DNA samples prepared from nontumorous lung parenchyma taken from lung cancer patients at surgery and revealed the presence of DNA adducts of the anti-benzo(a)pyrene diol-epoxide in 9 of 11 samples from smokers and in 2 of 2 ex-smokers. In only two samples from smokers the formation of adducts derived from syn-benzo(a)pyrene diol-epoxide was detected. A 15-fold variation in DNA adduct level was found in 11 of 13 DNA samples, with a range of 0.6-9.9 adducts of benzo(a)pyrene diol-epoxide/10(8) nucleotides. In samples containing both anti- and syn-benzo(a)pyrene diolepoxide-DNA adducts, the anti/syn adduct ratio is 2:1. A highly significant correlation was found between pulmonary microsomal aryl hydrocarbon hydroxylase activity and the level of benzo(a)pyrene diolepoxide-DNA adduct (r = 0.91; P < 0.001; n = 13). A crude linear correlation between the amounts of these adducts and those of bulky DNA adducts determined by 32P-postlabeling assay was observed in the same samples (r = 0.78; P < 0.02; n = 13). Thus this highly sensitive and specific procedure is suitable for measuring benzo(a)pyrene diolepoxide-DNA adducts in human tissues from environmentally exposed subjects and could be adapted to measure polycyclic aromatic hydrocarbons other than BP.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗

PubMed1992

Study of the safety and immunogenicity of the synthetic malaria SPf66 vaccine in children aged 1-14 years.

Safety and immunogenicity tests of the SPf66 malaria vaccine have been carried out on a population of children, aged 1 to 14 years, in the town of Tumaco, Colombia. Adverse reactions measured after each vaccination were local and minimal, and observed in only a small percentage of the vaccinated children. One year later, no delayed reaction was evident. The majority of the child population developed high antibody titres against SPf66 and the degree of response did not vary with age. These induced antibodies recognize the native parasite proteins, in particular the molecules from which the amino acid sequence of this vaccine was deduced. These studies demonstrate that the SPf66 vaccine is safe and highly immunogenic for use in children greater than 1 year old.

Adolescent↗

PubMed1992

The first field trials of the chemically synthesized malaria vaccine SPf66: safety, immunogenicity and protectivity.

This paper reports the results of the first field study performed to assess the safety, immunogenicity and protectivity of the synthetic malaria vaccine SPf66 directed against the asexual blood stages of Plasmodium falciparum. Clinical and laboratory tests were performed on all volunteers prior to and after each immunization, demonstrating that no detectable alteration was induced by the immunization process. The vaccines were grouped as high, intermediate or low responders according to their antibody titres directed against the SPf66 molecule. Two of the 185 (1.08%) SPf66-vaccinated and nine of the 214 (4.20%) placebo-vaccinated volunteers developed P. falciparum malaria. The efficacy of the vaccine was calculated as 82.3% against P. falciparum and 60.6% against Plasmodium vivax.

Amino Acid Sequence↗

PubMed1992

Expression of pulmonary cytochrome P4501A1 and carcinogen DNA adduct formation in high risk subjects for tobacco-related lung cancer.

Cigarette smoking is the strongest risk factor for lung cancer (LC), but genetically determined variations in pulmonary metabolism of tobacco-derived carcinogens may affect individual risk. Results from a case-control study on LC patients demonstrated the pronounced effect of tobacco smoke on pulmonary xenobiotic metabolism and prooxidant state, and suggested the existence of a metabolic phenotype at higher risk for tobacco-associated LC: LC patients who were recent smokers had significantly induced BP-3-hydroxylase (AHH) and ethoxycoumarin O-deethylase (ECDE) activities in lung parenchyma, when compared with smoking non-cancer patients. In recent smokers, lung AHH activity was positively correlated with the level of tobacco smoke-derived DNA adducts as determined by 32P-postlabelling. Pulmonary AHH activity also showed a good correlation with the intensity of immunohistochemical staining for cyt. P4501A by a monoclonal Ab in lung tissue sections: smoking and peripheral type of lung cancers were positively related to high levels of this cyt. P450 species, probably reflecting high rates of induction. These results suggest that high pulmonary CYP1A1 expression (controlling in part carcinogen DNA-adduct formation) in tobacco smokers, appears to be associated with LC risk. High risk subjects may thus be identifiable through genotyping assays for CYP1A1 polymorphism.

Aryl Hydrocarbon Hydroxylases↗

PubMed1992

Inhibitory effect of a Microcystis sp (cyanobacteria) toxin on development of preimplantation mouse embryos.

1. A soluble toxin, purified from the algae bloom of an eutrophic lake dominated by Microcystis, is a very effective inhibitor of early embryo development in a dose-response relationship. 2. Two- and 8-cell mouse embryos under the influence of Microcystis toxin do not reach the developmental stages of morula and blastocyst, respectively. 3. Actin cortex is disorganized without change in the microtubules structure. 4. Results are discussed in terms of the possible mechanisms by which the toxin arrests development considering, specifically, effects on the cytoskeleton and/or on voltage-insensitive transmembrane Ca2+ channels.

Animals↗

PubMed1992

Stereoselective metabolism of (-)-benzo[a]pyrene-7,8-diol by human lung microsomes and peripheral blood lymphocytes: effect of smoking.

Benzo[a]pyrene (B[a]P)-tetrols formed after stereoselective cytochrome P450-dependent metabolism from (-)-trans-7,8-dihydroxy-7,8- dihydrobenzo[a]pyrene [(-)-B[a]P-7, 8-diol] by lung microsomes (n = 19) and peripheral blood lymphocytes (n = 13) from lung cancer patients were measured, and the effect of smoking explored. B[a]P-tetrols were quantified by an HPLC/fluorescence assay with a detection limit of approximately 300 attomol, after incubation with peripheral blood lymphocytes or microsomes from lung cancer patients who were current cigarette smokers, ex-smokers and non-smokers. In lymphocytes from these subjects, high, medium and low metabolic activities respectively for (-)-B[a]P-7,8-diol to tetrol conversion were found, but there was no statistically significant difference between smokers, ex-smokers and non-smokers. When the B[a]P-tetrol formation by human lung microsomes was measured, recent smokers had 4- to 7-fold higher (P = 0.04) metabolic activity than ex-smokers and non-smokers. The mean lung microsomal arylhydrocarbon hydroxylase (AHH) activity was three times higher in smokers than in non-smokers and was undetectable in ex-smokers. AHH activity was correlated with tetrol formation in the same lung microsomal samples (r = 0.62, P less than 0.01 in smokers; and r = 0.67, P less than 0.01 in all subjects). When subjects were grouped according to smoking habits, however, no correlation was detected between mean tetrol formation by lung microsomes and that of lymphocytes. Thus, lymphocytes cannot serve as a surrogate for lung microsomes concerning the pulmonary metabolism of (-)-B[a]P-7,8-diol. The much higher B[a]P-tetrol formation observed in lung microsomes from smokers is in accord with a reported higher pulmonary AHH activity, cytochrome P450IA level, and CYP1A1 gene expression in recent tobacco smokers.

Adolescent↗

PubMed1992

Safety and immunogenicity of the synthetic malaria vaccine SPf66 in a large field trial.

In the first field trial with synthetic malaria vaccine SPf66 in a large population naturally exposed to malaria, 9957 persons greater than 1 year old and residing on the Colombian Pacific coast received three doses of the vaccine. To evaluate vaccine safety, clinical observations were made 30 min and 48 h after each immunization. There were no adverse reactions in 95.7% of cases. In the 4.3% of cases with adverse reactions, local induration and erythema were the most frequent. In a randomly selected group of vaccinees, anti-SPf66 antibody titers were measured after the third dose: 93% of the vaccinees raised antibodies to SPf66. Among these, 55% had titers greater than 1:1600. These results demonstrate the safety and immunogenicity of the SPf66 vaccine in a large field trial.

Adolescent↗