Biomedical subjects
Publications and source records attributed to R Ruiz.
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We describe an immunoturbidimetric assay for estimating the concentration of apolipoproteins (apo) A-I and B in serum with a Cobas Bio centrifugal analyzer. Several analytical variables were studied: pH, temperature, wavelength, reaction time, sample pretreatment, antisera dilution, concentration of NaCl, phosphate buffer, and PEG 6000; a good optical response was obtained with small volumes of sample and antisera. Imprecision was low, with intrarun coefficient of variance (CV) from 1.1 to 2.8% and interrun CV from 1.8 to 3.2%. We demonstrated a good correlation between our method and radial immunodiffusion for apo A-I (r = 0.975) and apo B (r = 0.980). Reference values were calculated from a sample of 494 healthy subjects, and separate intervals for the ratio of apo A-I to apo B in gender and age subgroups were established.
Surveillance was conducted one day each week from December 1992 through May 1993 to determine the clinical features and etiology of diarrhea among a population in a suburban community of Lima, Peru. Patients who had had three or more loose stools during the previous 24 hr were enrolled at a clinic located in the community or at a nearby regional hospital. A total of 143 cases of diarrhea were detected for an overall rate of 7.1 cases per 1,000 population. The enteropathogens isolated were Vibrio cholerae 01 (31%), enterotoxigenic Escherichia coli (22%), and Salmonella, Shigella, Campylobacter, and Aeromonas species (10%). Specimens from the remaining cases were negative for enteropathogens. All isolates of V. cholerae were susceptible to tetracycline, doxycycline, nalidixic acid, norfloxacin, trimethoprim-sulfamethoxazole, trimethoprim, gentamicin, chloramphenicol, and cephalothin. Cases of diarrhea associated with V. cholerae were more common among adults, and more likely to experience severe dehydration and require hospitalization than the non-cholera cases. Data indicated that among the cases diagnosed, V. cholerae and enterotoxigenic E. coli were the more common causes of diarrhea in a suburban community of Lima during the summer season.
The possible alteration in diastolic function as a result of physiological left ventricular hypertrophy was evaluated in 28 male marathon runners (mean age 38.6 +/- 5.7 years) using Doppler echocardiography. The subjects were divided into two groups according to the intensity of training and chronometered running times: Group I (n = 14), 80-100 km weekly and marathon times under 3 hours; and Group II (n = 14), 30-50 km weekly and marathon times between 3 hours 15 min. and 3 hours 45 min. A control group (n = 14) of similarly aged sedentary individuals free of cardiovascular disease was used for comparisons. The following parameters were analyzed: (a) left ventricular mass and left ventricular mass index by means of M mode two-dimensional guided echocardiography; (b) peak velocities of E and A waves, E/A peak velocities ratio, E/A velocity-time integrals ratio, E wave/total diastolic flow velocity-time integrals and A wave/total diastolic flow velocity-time integrals (last one also called atrial filling fraction) that, together with E wave deceleration time, were obtained from pulsed Doppler recordings of transmitral flow; (c) isovolumic relaxation time measured from a continuous Doppler recording of aortic ejection flow. Left ventricular mass index was significantly greater in both groups of marathon runners with respect to controls (group I: 121.1 +/- 15.5 vs 81.8 +/- 11.1 g/m2, p < 0.01; group II: 106.5 +/- 21.1 vs 81.8 +/- 11.1 g/m2, p < 0.01), but there were no significant differences in any of the diastolic function parameters analyzed (Anova and Scheffe tests).(ABSTRACT TRUNCATED AT 250 WORDS)
BACKGROUND: Reentrant ventricular tachycardia and fibrillation probably have different electrophysiological bases. Regional conduction delay during sinus rhythm seems to be greatest in patients with spontaneous sustained ventricular tachycardia than in patients with spontaneous sustained ventricular fibrillation. We investigated the prevalence and significance of late potentials in patients with documented VT or VF in the setting of coronary diseases and other organic heart diseases. PATIENTS AND METHODS: Nineteen patients with a history of spontaneous sustained ventricular tachycardia (11 patients) or fibrillation (8 patients) were studied with signal-averaged ECG. All patients had been resuscitated of sudden cardiac death. All recordings were made in sinus rhythm in an antiarrhythmic free state following the recommendations of the Committee of the European Society of Cardiology for data acquisition and analysis of ventricular late potentials using Signal Averaged Electrocardiography. The relationship between this late potentials and tachyarrhythmia inducibility during electrophysiologic study were established. RESULTS: Abnormal late potentials were found in 79% of patients with sudden cardiac death. Patients with spontaneous ventricular tachycardia had a longer ventricular activation time in sinus rhythm than did patients with spontaneous ventricular fibrillation, but this difference did not reach statistic significance. The only analysis of late potentials could not discern the mechanism of sudden cardiac death. However when sudden cardiac death was caused by a spontaneous ventricular tachycardia, a good correlation between abnormal late potentials and induced ventricular tachycardia by programmed stimulation was found. Quantitative indices of late potentials did not correlate with ventricular tachycardia cycle length. CONCLUSIONS: 1) We have found and elevated incidence of abnormal late potentials in patients with sudden cardiac death, and 2) only when the mechanism of sudden cardiac death was a spontaneous VT, we were able to correlate abnormal late potential with provoked ventricular tachycardia during electrophysiologic study.
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Lentils were subjected to natural fermentation for 4 days at 30 degrees C. The pH value fell to 3.8 during the process. alpha-Galactosides and sucrose were not detected in fermented lentils but a significant increase in the fructose content was observed. In fermented lentils the neutral detergent fibre, cellulose and hemicellulose contents decreased and the lignin content increased. After fermentation the riboflavin content was higher and the trypsin inhibitor activity decreased.
Intracerebral microdialysis combined with a sensitive and specific radioimmunoassay was used to monitor the neuronal release of somatostatin (somatostatin-like immunoreactivity, SLI) in the dorsal hippocampus of freely moving rats. The sensitivity of the radioimmunoassay was optimized to detect < 1 fmol/ml. The basal concentration of SLI in 20-min dialysate fractions (5 microliters/min) collected 24 h after probe implantation was stable over at least 200 min. The spontaneous efflux dropped by 54 +/- 6.4% (p < 0.05) when Ca2+ was omitted and 1 mM EGTA added to the Krebs-Ringer solution and by 65.5 +/- 3.2% (p < 0.05) in the presence of 1 microM tetrodotoxin. Depolarizing concentrations of the Na+ channel opener veratridine (6.25, 25, 100 microM) induced 11 +/- 2 (p < 0.05), 17 +/- 2 (p < 0.05), and 21 +/- 5 (p < 0.01) fold increase in SLI concentration, respectively, during the first 20 min of perfusion. The effect of 100 microM veratridine was blocked by coperfusion with 5 microM tetrodotoxin (p < 0.01) and reduced by 79% (p < 0.01) in the virtual absence of Ca2+. Neuronal depolarization by 20 min of perfusion with Krebs-Ringer solution containing 25 and 50 mM KCl and proportionally lowered Na+ increased the dialysate SLI 4.4 +/- 1 (p < 0.05) and 17 +/- 3 (p < 0.01) fold baseline, respectively. Ten micromolar ouabain, a blocker of Na+,K(+)-ATPase, increased the dialysate SLI 15-fold baseline, on average (p < 0.05), during 80 min of perfusion. The results demonstrate the suitability of brain microdialysis for monitoring the neuronal release of SLI and for studying its role in synaptic transmission.
Groups of 122 Peruvian adults of low socioeconomic level (SEL) and 125 of high SEL received a randomly allocated 5 x 10(9)- or 5 x 10(8)-CFU dose of CVD 103-HgR live oral cholera vaccine or a placebo. The vaccine was well tolerated. Vibriocidal seroconversions occurred in 78% of high-SEL and 72% of low-SEL subjects who ingested the high dose and in 78 and 49%, respectively, of those who received the low dose.
The presence of many enteropathogens which are not easily detectable by routine stool culture has led to the development of alternative diagnostic methods. One of these techniques, nucleic acid probe hybridization, has been used to identify Shigella spp. and enteroinvasive Escherichia coli (EIEC) in stool specimens through the detection of genetic material encoded by a specific large approximately 200-kbp virulence-related plasmid. In the present study, an alkaline phosphatase-labelled oligonucleotide probe developed to detect the gene for ipaH, a repetitive genetic sequence thought to be present on both the virulence-related plasmid and the chromosomes of all strains of Shigella and EIEC, was tested in a developing-country setting through a prospective clinical trial. In a group of 219 Peruvian adults and children with acute gastroenteritis, the ipaH probe detected 85% of cases of shigellosis and demonstrated a specificity of 95% when compared with simultaneous detection by several stool culture techniques. Additionally, three cases of EIEC infection which could not be diagnosed by culture methods alone were detected with the ipaH probe and were confirmed by plasmid analysis and Sereny testing. These preliminary results suggest that, with further research, the ipaH probe should prove to be a useful and rapid adjunct in the diagnosis of acute gastroenteritis in developing countries.
The effect of temperature and length of storage on the stability of alpha-tocopherol in UHT milk was studied by HPLC. The effect of water activity conditions during storage of milk powder on the stability of the same vitamin was also studied. Losses of alpha-tocopherol occurred in UHT milk after 1 mo of storage at 30 degrees C; losses increased as storage time increased. In general, when the storage temperature changed from 30 to 40 degrees C, decrease in alpha-tocopherol content was greater. Short periods of frozen storage of the UHT milk (up to 60 d) had no effect on alpha-tocopherol content. However, frozen storage from 4 to 8 mo produced losses in alpha-tocopherol. When water activity was increased, the alpha-tocopherol content in milk powder decreased significantly after 2 mo of storage at 20 degrees C.
BACKGROUND: During the last few years the application of Western immunoblotting in the study of human infection by Rickettsia conorii has led to the development of a new method of serologic diagnosis of the Mediterranean exanthematous fever. METHODS: The pattern of reactivity of serum samples sequentially obtained in the course of infection versus R. conorii antigens (Malish 7 strain) purified in discontinued density gradient and separated by SDS-PAGE was analyzed by Western immunoblotting. RESULTS: The presence of typical profiles of rickettsial infection similar to those observed in the common forms of presentation of the Mediterranean exanthematous fever was demonstrated in a case of accidental infection transmitted via aerosol and followed by an incomplete clinical picture after the early administration of specific antibiotic therapy and in a patient with signs and symptoms characteristic of Mediterranean exanthematous fever in whom the results of indirect immunofluorescence tests were repeatedly negative. CONCLUSIONS: Western immunoblotting may be a specially useful technique as a complementary procedure in the laboratory to guide in the diagnosis of Mediterranean exanthematous fever in special situations.
The effect of storage temperature and storage time on the retinol content of four commercial unfortified whole UHT milk samples was studied by HPLC. Significant losses of retinol in these milks were observed after 1 month of storage at 30 degrees C. Losses generally increased with storage time. Increasing the storage temperature from 30 degrees C to 40 degrees C had a variable effect depending on the particular milk. Short periods of frozen storage (up to 60 days) had no effect on the retinol content. However, frozen storage time from 4 to 8 months led to significant (P < 0.05) losses in retinol content. The effect of water activity and temperature conditions during storage of unfortified whole milk powder on the stability of retinol was also studied. Increasing the activity of water and temperature of storage significantly lowered the retinol content in milk powder.
The clinical features of a patient with cholesterol embolism are presented. Histopathological examination showed the typical clefts of cholesterol in the skin and renal vessels. We believe this entity is under-reported in the dermatological literature.
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With systemic unipolar pacemaker control by chest wall stimulation and interference we have obtained further data of the sensing function in more the 5000 clinical controls. A better classification of abnormal sensing function is important for a full electrocardiographic interpretation. We have established that the oversensing is always a primary evident or concealed phenomenon. Undersensing is a primary or secondary phenomenon provoked by a concealed oversensing in refractory period.
Thirty-one patients with acute pancreatitis were prospectively evaluated using the Early Prognostic Risk Factors of Ranson and Bank & Wise, in order to assess severity of that condition. The purpose was to determine the usefulness of such factors as clues to orient diagnosis and treatment of acute pancreatitis, particularly in the most severe clinical forms; and the factibility of using them in our setting. The presence of 4 or more of Ranson's and/or 1 or more of Bank & Wise Factors fulfilling positive criteria, identified the patients with a high risk of complications and mortality. Hypocalcemia, leucocytosis and hyperuricemia were the most frequent findings in this group. The development of Early Objective Prognostic Risk Factors in acute pancreatitis, as a clinical concept, has improved the management of these patients. It allows to establish diagnosis and therapeutics upon objective basis.
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