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Biomedical subjects

C Contreras

Publications and source records attributed to C Contreras.

At least 19 recordsLinked to original sources
PubMed2002

Isolation and identification of the photodegradation products of the photosensitizing antidepressant drug clomipramine. Phototoxicity studies on erythrocytes.

The isolation and identification of the photodegradation products of clomipramine (CIP) in phosphate buffered saline (PBS pH 7.4 and 6.0) solution and methanol under aerobic conditions were studied. Six compounds were identified and four of them were isolated and characterized by spectroscopic methods. A radical mechanism with the participation of the solvent is proposed for the photodegradation of CIP which undergoes homolytic cleavage of the carbon-chlorine bond and also photooxidation of the amine group. CIP was able to induce photohemolysis when it was irradiated in PBS pH 7.4 and in PBS pH 6.0 containing a suspension of human red blood cells (RBCs). The photohemolysis experiments in the presence of additives DABCO and GSH showed nearly total inhibition of drug-induced photohemolysis. The efficient inhibition of photohemolysis by the radical scavenger GSH compared with the inhibition show by DABCO suggests a moderate effect by singlet oxygen. Clomipramine-N-oxide was the unique photoproduct able to induce hemolysis and photohemolysis when it was incubated and irradiated with RBCs for 1 h. A mechanism involving singlet oxygen, radicals and photoproducts is suggested for the reported phototoxicity.

Aerobiosis↗
PubMed2001

Relationship of obesity distribution and peripheral arterial occlusive disease in elderly men.

OBJECTIVE: To examine the relationships between total body fatness and abdominal fat distribution with peripheral arterial disease. DESIGN: Cross-sectional. SUBJECTS: Population-based sample of 708 men aged 55-74. MEASUREMENTS: Body mass index (BMI) to estimate total body fatness and waist-to-hip ratio for abdominal fat distribution; peripheral arterial disease defined by ankle/brachial index <0.9; cardiovascular risk factors. RESULTS: Peripheral arterial disease was observed in 13.4% of subjects. BMI did not correlate with peripheral arterial disease, whereas an increased waist-to-hip ratio over 0.966 (median value) doubled the prevalence of arterial disease. After controlling for smoking, diabetes, hypertension, high-density lipoprotein cholesterol and triglycerides, increased waist-to-hip ratio was independently associated with peripheral arterial disease (odds ratio 1.68; 95% confidence interval 1.05-2.70). CONCLUSION: Abdominal fat distribution, but not total body fatness, is associated with peripheral arterial occlusive disease, independently of concurrent cardiovascular risk factors.

Adipose Tissue↗
PubMed2000

Total arsenic, lead, cadmium, copper, and zinc in some salt rivers in the northern Andes of Antofagasta, Chile.

The pre-Andes water in the region of Antofagasta is the main drinking and irrigation water source for approximately 3000 Atacameña (indigenous) people. The concentration for soluble elements (filtration in field through a 0.45-microm filter) was: Cd < 0.1 ng/ml; Pb < 0.5 ng/ml; and Zn and Cu between 1 and 10 ng/ml. In particulate material the concentrations were: for Cd < 0.1 ng/ml; for Pb < 0.3 ng/ml; and for Zn and Cu less than 1 ng/ml. The total content of these elements is far below the international recommendations (WHO) and the national standards (N. Ch. 1333 mod. 1987 and 409-1 of 1984). On the other hand, in some rivers a very high arsenic concentration was found (up to 3000 ng/ml) which exceed more than 50 times the national standard. In order to verify the analytical results, inter-laboratory and comparison with different determination methods have been done.

Chile↗
PubMed1999

Occurrence of Escherichia coli O157:H7 in hamburgers produced in Brazil.

The occurrence of Escherichia coli O157:H7 was evaluated in 886 samples of hamburgers produced by eight manufacturers in the south and southeast of Brazil from January to September of 1997. The pathogen was not detected in any of the samples analyzed, although 17 (1.9%) showed the presence of E. coli strains, which presented agglutination with O157 antiserum. These strains were not confirmed, since a subsequent identification indicated that they were fermentation positive for sorbitol, incapable of agglutination with the antisera of other commercial brands, and nonproducers of verocytotoxins. A high rate of false-presumptive-positive tests was observed with strains of enterobacteria when isolated by the culture method and when using a commercially purchased enzymatic immunoassay. This high rate of false presumptive positives was likely because the initial screening for sorbitol-negative strains was carried out using phenol red sorbitol 4-methylumbelliferyl-beta-D-glucuronide agar, which was shown to be inadequate for this purpose.

Animals↗
PubMed1996

Microculture in biphasic medium with silicone-coated slides for isolation of mycobacteria.

The study reported here, seeking to develop a simple, practical, sensitive, and inexpensive technique for microbial diagnosis of tuberculosis, used a combination of biphasic media and microculture techniques to augment the sensitivity of traditional culture methods. A total of 540 sputum samples (5 mL each) were obtained from 180 patients with suspected tuberculosis in Mexico City. These samples were treated with Hanks reagent, neutralized with 25% HCl, and centrifuged. In each case the resulting residue was combined with liquid media (Sula medium or a phosphate-buffered control solution) and was inoculated into a bottle containing a solid medium (Löwenstein-Jensen-Holm or Middlebrook). A silicone-coated slide appropriate for culture of hydrophobic mycobacteria was inserted in each bottle, and the cultures (examined weekly) were incubated at 37 degrees C until the first macroscopic bacterial growth was detected or for up to eight weeks if none was detected. When such growth was detected, or at the end of eight weeks, each slide was withdrawn from the bottle, sterilized, stained by Kinyoun's method, and examined microscopically. Following 2-4 weeks of incubation, macroscopic bacterial growth was detected in 71 bottles and was confirmed by microscopic examination of the corresponding slides. No macroscopic bacterial growth was found in any of the remaining 469 bottles, but microscopic growth was observed on 77 of the slides examined after eight weeks. The authors conclude that this method represents a noteworthy improvement over standard culture methods in terms of bacterial isolation and suggest that its case, economy, and practicality make it suitable for application in developing countries.

Cell Culture Techniques↗
PubMed1993

[The recommendable frequency for performing electrocardiograms in the hypertension patient].

OBJECTIVE: To obtain information on how often electrocardiograms (ECG) should be carried out during hypertense patients' follow-up. DESIGN: A retrospective, descriptive study. SETTING: La Mina Primary Care Centre. PATIENTS: Out of 1780 hypertense patients over 14 years old monitored at our Health Centre, 352 were selected by random sampling. MEASUREMENTS AND MAIN RESULTS: Their first ECG after the AHT diagnosis was analysed. Those patients with a normal initial ECG, a minimum of one year's monitoring, and absence of a chronic limitation of air flow, diabetes mellitus or cardiopathy were included in the study. The ECGs following the first ECG were analysed sequentially until an anomalous ECG was detected. Final sample: 98 patients (average age 53, SD 12.8; 33 men and 65 women). 89 (91.8%) had light-to-moderate AHT. The average interval between the initial normal ECG and the first pathological ECG was 36 months (SD 16.9). The most common electrocardiographic irregularities were the T minor wave (34.5%), the greater unevenness of the ST (17.2%) and left ventricular hypertrophy (13.8%). A total of 29 patients presented a pathological ECG during an average monitoring period of 61 months (C.I. 95%; 50-72). These were only significantly different from the remaining 69 as regards age. Those patients over 54 (n = 51) had significantly more irregularities (21) than those under 55 (n = 47) (8 irregularities) (p = 0.006), the main increase being between the ages of 55 and 60. CONCLUSIONS: The recommendation to carry out an ECG every 2 or 3 years when monitoring a hypertense patient with a normal initial ECG and without additional pathologies, could be extrapolated from our study. The time interval could be shortened for older patients.

Adult↗
PubMed1992

[Major and minor changes in the electrocardiogram of the hypertensive patient].

OBJECTIVE: To determine the prevalence and characteristics of electrocardiograph deviation in such hypertensive patients. DESIGN: Retrospective descriptive study of a representative sample of patients with high blood pressure. SITE. Primary attention centre. PATIENTS: The sample consists of 352 patients, systematically random selected from a pool of 1780 patients suffering from hypertension, aged over 14 years, attending the centre (119 males (34%) and 233 females (66%). Average age 59.4 +/- 13.5 years). MAIN MEASUREMENTS AND RESULTS: The first ECG reading after diagnosis of hypertension was analysed and codified according to the pooling project criteria. 38.9% present electrocardiograph deviations, the most frequent being minor wave 1 (12%), significant breaking up of the ST (9%) and left ventricular hypertrophy (5.1%), the latter more frequent in women (p = 0.03). Age, systolic arterial blood pressure and the time the condition had been in existence, certain associated chronic diseases, and use of pharmaceutical drugs acting cardiovascularly, are positively related to the deviation in ECG (p < 0.05). CONCLUSIONS: The value of ECG in the treatment of high blood pressure sufferers is indicated.

Age Factors↗
PubMed1992

[Study of diffuse chronic hepatopathy in the outpatient context].

OBJECTIVE: Description of the general characteristics of patients with Diffuse Chronic Hepatopathy (DCH) in an ABS. DESIGN: Empirical study of a prospective and retrospective type. Site. Primary Care. ABS La Mina. Sant Adrià de Besòs. PATIENTS AND OTHER PARTICIPANTS: All patients diagnosed as suffering DCH since 1984, in line with histological or clinical--morphological criteria accepted in the literature. MAIN MEASUREMENTS AND RESULTS: Using a data base of the centre's morbidity and mortality register, 287 reports of patients over 14 years old defined as having DCH were examined. 222 cases met the established criteria. Most of these were males (68%), and to an even higher proportion in the group with alcoholic etiology (84%), which was the most common cause of DCH (64.4%). There was a lower number of complications and deaths attributable to DCH than in published hospital series. CONCLUSIONS: Among the characteristics of DCH in a natural population using the health services, it is important to note the predominance of compensated forms having a rate of complications and deaths attributable to DCH significantly lower than what was observed in hospital series. This information may be of use in planning activities at the ABS level.

Adolescent↗
PubMed1991

Serum C-reactive protein in childhood meningitis in countries with limited laboratory resources: a Chilean experience.

Quantitative C-reactive protein (CRP) was determined sequentially by nephelometry and photometry from a finger prick serum sample in 67 children with bacterial meningitis (BM) and 16 children with aseptic meningitis (AM). The initial mean CRP value of 180 mg/liter in children with BM differed significantly from the 12 mg/liter found in those with AM (P less than 0.001). In BM a slow descent instead of rapid normalization or a secondary increase in sequential CRP values were early indicators of complications during recovery, such as resistance to the antibiotic. A significant difference in the mean CRP values between uneventful and complicated courses of BM was observed from the fourth day on (P less than 0.001). The measurements obtained with nephelometry correlated reliably with the more widely available photometry (r = 0.99). Easily performed rapid CRP determinations can considerably improve the quality of care in meningitis patients, especially in those situations where facilities for performing bacterial cultures or antibiotic susceptibility testing are not available.

C-Reactive Protein↗
PubMed1990

Percutaneous ablation of gallstones.

The purpose of this study was to determine if gallstones could be safely and effectively ablated in the pig using a proprietary percutaneous rotor-tipped catheter, the Kensey-Nash Lithotrite (KNL). All gallstones in a single human gallbladder were defined as a gallstone set. Human gallstone sets not meeting current treatment criteria for extracorporeal shock wave lithotripsy (ESWL) were placed in the gallbladder (GB) of male pigs (N = 8; 80-100 kg). A percutaneous transhepatic guide wire was put into the GB and the abdomen closed. The KNL was then introduced under fluoroscopy using the Seldinger technique and activated. Gallstone ablation was monitored by tactile and auditory feedback to the operator and by fluoroscopy. Once completed the device was withdrawn, the GB irrigated, and the 9F sheath removed. Animals were sacrificed immediately (Group 1, N = 4) and at 28 +/- 5 days (Group 2, N = 4). Gallstones were ablated in 26 +/- 8 min. No pig had significant hemorrhage, GB perforation, or pancreatitis. One acute animal had stone fragments greater than 2 mm in the gallbladder. No other animals had any fragments greater than 1 mm present in the GB, cystic duct, common duct, ampulla, or duodenum. Histologic examination of the GB showed acute hemorrhagic mucosal injury in Group 1 and extensive mucosal regeneration with some stone fragment granulomata and mural fibrosis in Group 2. We conclude that percutaneous gallstone ablation with the KNL is safe and effective in this short-term pig model and appears to be a safe procedure for gallstone ablation. Long-term safety and effectiveness remain to be demonstrated. This device should be useful for treatment of symptomatic gallstones in patients not treatable by ESWL.

Animals↗
PubMed1990

[Captopril in single doses in the treatment mild-moderated arterial hypertension].

The effect of single dose (50 mg) Captopril (C) used either alone or associated to diuretics (50 mg hydrochlorothiazide -HCTI) in the treatment of mild-moderate essential arterial hypertension was studied in a multicentric study. Eighty eight patients were chosen. After a minimum of 4 month follow-up period 53.4% responded (BDP less than 95 mm Hg) to single dose C (group 1:47 patients), 89.77% to 50 mg C in single dose together with 50 mg HTIT (group 2: 32 patients), 95.45% of two 50 mg doses of C and 50 mg HCIT (group 3: 5 patients), and 97.72% responded to 3 doses of C and 50 mg of HCTI (group 4: 2 patients). The decrease in blood pressure values was statistically significant (p, 000, Wilcoxon test) in groups 1 and 2, having a mean decrease in blood pressure (BP) of 14%. In group 1 (n = 42) the SBP which initially was 165.72 +/- 11.32, decreased to 148.28 +/- 11.5 and the DBP decreased from 101.55 +/- 5.68 to 87.28 +/- 6.59. In group 2 (n = 32) the SBP decreased from 173.50 +/- 14.08 to 152.44 +/- 20.8 and the DBP from 103.34 +/- 5.29 to 87.47 +/- 6.39. The response to monotherapy could not be statistically correlated either to early essential hypertension or to the patients age. Treatment was discontinued in three cases due to the secondary effects, cough, ageusia and nervousness, showing the remaining patients a good tolerance. No changes were observed in the analytical parameters. This study shows the usefulness and tolerance of single dose C as the initial treatment of mild to moderate essential hypertension.

Adult↗
PubMed1979

Isoxsuprine infusion to the pregnant rabbit and its effect on fetal lung surfactant.

Rabbit does, pregnant on the 28th day, were infused with isoxsuprine 2.5 mg/kg body weight/h in 50 ml 5% glucose, or with glucose only. The isoxsuprine caused maternal heart rate to increase and blood pressure, mean and diastolic, to decrease. The volume of fetal pulmonary fluid (FPF) and the wet lung weight/body weight ratio were significantly lowered by isoxsuprine. Lecithin/sphingomyelin ratio of FPF in isoxsuprine-infused animals was higher, compared with controls, not infused. Minimal surface tension of FPF, evaluated with pulsating bubble, was significantly lower in treated fetuses. Histologic examination of the fetal lungs after fixation with potassium dichromate and mercuric chloride showed that in isoxsuprine-treated litters FPF contained more granular and sudanophilic material. The results offer further evidence that isoxsuprine causes dehydration of fetal lungs and a release of pulmonary surfactant.

Animals↗
PubMed1979

Intranasal meningoencephalocele with recurrent meningitis.

Two patients presented with repeated bouts of meningitis. RISA cisternography established the diagnosis in both cases. An intranasal meningoencephalocele was the cause of these infections. Frontal craniotomy and section of the peduncular connection of the meningoencephalocele and sealing of the bony defect was successfully performed in both cases. Postoperative investigations showed complete cure.

Child↗