Selecting and improving activated homogeneous catalytic processes for pollutant removal. Kinetics, mineralization and optimization.

The degradation of a model pollutant, tartrazine, very used in food industry and usually present in WWTPs effluents and surface waters, was investigated by nine activated homogeneous catalytic processes, namely, Fe3+/H2O2, Fe2+/H2O2, UV/H2O2, UV/S2O82-, UV/Fe2+/H2O2, UV/Fe3+/H2O2, UV, VIS/Fe3+/H2O2, and VIS/Fe3+/H2O2/C2O42-. In order to compare the mineralization and oxidation ability of each process, the removal of dye, chemical oxygen demand (COD) and total organic carbon (TOC) were analyzed, as well as the overall kinetic rate constant. Also, the different oxidation path-ways (direct photolysis and/or oxidation by free radicals) were estimated for each system. After the comparison, the Fenton process, which had the highest mineralization values, was tested in luminous and dark phases using designed experiments, and the influences of all operating variables were studied by RSM.

Exposure to extrinsic risk factors in prevalence surveys of hospital-acquired infections: a methodological approach.

The difficulties encountered in studying the presence of extrinsic risk factors in the framework of prevalence surveys of hospital-acquired infections (HAI) have led to the use of a variety of methodological approaches. This study examined the effect of retrospective approaches for obtaining data regarding exposure to extrinsic risk factors. The EPINE database for 1990 was used and a simulation model was created. All the evaluated approaches differed in their impact upon the association between risk factors and infections. Prevalence of exposure on the day of the survey, prevalence of exposure at any time before the survey was conducted, and total prevalence were found to be significantly associated with the probability of exposure and duration of exposure. For exposure periods of less than four days, the prevalence of exposure during the week prior to the survey was higher than that encountered on the day of the survey. In studying exposure to risk factors retrospectively, no evidence-based justification could be found to determine how many days prior to the day of actual exposure should be included in the study. However, the site of infection determined the proportion of devices removed due to HAI, and this proportion was not very high in this study. Limiting data to recording the presence of the risk factor on the day of the survey, without investigating past exposures, can provide an adequate estimate of the burden of extrinsic risk factors in one-day, point-prevalence surveys.

Physico-chemical treatment for the depuration of wine distillery wastewaters (vinasses).

In the present work, an integrated Fenton-coagulation/flocculation process was applied for the depuration of wine distillery wastewaters, commonly known as "vinasses". This study evaluates the Fenton process (H2O2/Fe2+), involving oxidation--in a first stage and coagulation/flocculation (using Ca(OH)2 as base-precipitant)--in a second stage for the removal of chemical oxygen demand (COD). The experimental variables studied were the dosages of hydrogen peroxide and iron salts, the molar ratio [H2O2]o: [Fe2+]o, the effluent dilution and the manner in which the reagents were added (splitting the reagent dose of hydrogen peroxide and ferrous salt into different fractions). The optimal operating conditions of the integrated process were: [H2O2]o = 0.5 mol/L using an optimal concentration ratio [H2O2]o: [Fe2+]o= 15 mol/mol. Under these conditions, the COD removal was 74%.

Degradation of wine distillery wastewaters by the combination of aerobic biological treatment with chemical oxidation by Fenton's reagent.

The degradation of wine distillery wastewaters by aerobic biological treatment has been investigated in a batch reactor. The evolution of the chemical oxygen demand, biomass and total contents of polyphenolic and aromatic compounds was followed through each experiment. According to the Contois model, a kinetic expression for the substrate utilization rate is derived, and its biokinetic constant is evaluated. The final effluents of the aerobic biological experiments were oxidized by Fenton's reagent. The evolution of chemical oxygen demand, hydrogen peroxide concentration and total contents of polyphenolic and aromatic compounds was followed through each experiment. A kinetic model to interpret the experimental data is proposed. The kinetic rate constant of the global reaction is determined.

Increase of immunity to rubella and interruption of rubella transmission in Gipuzkoa (Basque Country, Spain) after an enhanced vaccination programme.

In Spain, vaccination against rubella was initiated in schoolgirls in the mid-1970s. In Gipuzkoa, subsequent extensions to the vaccination schedule culminated in 1992 with the introduction of the two-dose measles, mumps and rubella vaccine in children and adolescents of both sexes. Moreover, in 1985 a programme for the identification and vaccination of non-immune parturient women was implemented in the region's main hospital. The prevalence of rubella-susceptible parturient women decreased from 3.7 % at the beginning of the study to < 1.5 % by 1992. Despite this overall decrease, 4.8 % of adolescent parturients were susceptible to rubella during 2001--2002. From 1984, the number of reported cases of rubella (children and adults) progressively decreased until 1997, after which there have been no cases of indigenous rubella. There have been no cases of reported congenital rubella since 1984. These results indicate that the vaccine policy carried out in this geographical area has been effective in achieving considerable progress towards rubella elimination.

Degradation of olive mill wastewater by the combination of Fenton's reagent and ozonation processes with an aerobic biological treatment.

Degradation of olive mill wastewater (OMW) by means of two chemical oxidation processes (Fenton's reagent and ozonation) and their consecutive treatments with aerobic microorganisms have been studied. Fenton's reagent treatment moderately reduces COD and to a greater extent the polyphenolic compounds. Ozonation contributed to low conversion of COD and moderate reduction of polyphenols. The aerobic biological treatments degrade to values higher than 70% and 90% for COD and polyphenolic compounds, respectively. A kinetic study has been carried out in each process, determining the representative kinetic parameters of each model.

Kinetic model for phenolic compound oxidation by Fenton's reagent.

A kinetic model is developed for the oxidation of phenolic compounds by Fenton's reagent. In the first stage a rigorous kinetic model is applied to calculate the different kinetic rate constants for the oxidation process of p-hydroxybenzoic acid. In a second phase a competitive method is applied to calculate these kinetic constants for another 10 phenolic compounds present in agroindustrial and pulp paper wastewaters. These 10 phenolic compounds were: beta-resorcylic acid, 3-(4-hydroxyphenyl)-propionic acid, ferulic acid, protocatechuic acid, caffeic acid, p-coumaric acid, vanillic acid, syringic acid, veratric acid and 3,4,5-trimethoxybenzoic acid.

Oxidation of p-hydroxybenzoic acid by UV radiation and by TiO2/UV radiation: comparison and modelling of reaction kinetic.

The phenolic compound p-hydroxybenzoic acid is very common in a great variety of agroindustrial wastewaters (olive oil and table olive industries, distilleries). The objective of this work was to study the photocatalytic activity of TiO2 towards the decomposition of p-hydroxybenzoic acid. In order to demonstrate the greater oxidizing power of the photocatalytic system and to quantify the additional levels of degradation attained, we performed experiments on the oxidation of p-hydroxybenzoic acid by UV radiation alone and by the TiO2/UV radiation combination. A kinetic model is applied for the photooxidation by UV radiation and by the TiO(2)/UV system. Experimental results indicated that the kinetics for both oxidation processes can be fitted well by a pseudo-first-order kinetic model. The second oxidation process can be explained in terms of the Langmuir-Hinshelwood kinetic model. The values of the adsorption equilibrium constant, K(pHB), and the second order kinetic rate constant, k(c), were 0.37 ppm(-1) and 6.99 ppm min(-1), respectively. Finally, a comparison between the kinetic rate constants for two oxidation systems reveals that the constants for the TiO2/UV system are clearly greater (between 220-435%) than those obtained in the direct UV photooxidation.

Kinetics of the reaction between ozone and phenolic acids present in agro-industrial wastewaters.

The kinetics of the ozonation of three phenolic acids is investigated from ozone absorption experiments in a semi-continuous reactor. After the evaluation of stoichiometric ratios for the individual reactions between ozone and each phenolic acid, the oxidation of p-hydroxybenzoic acid by ozone is performed in a first stage. The influence of the operating variables on the degradation process is established, and the application of a mass transfer with chemical reaction model based on the film theory leads to the determination of the reaction orders and kinetic rate constants. The experimental absorption rates obtained agree well with those calculated theoretically. In the second stage, a mixture of ferulic acid (4-hydroxy-3-methoxycinnamic acid), beta-resorcylic acid (2,4-dihydroxybenzoic acid) and p-hydroxybenzoic acid is ozonated under different experimental conditions. The kinetic study is performed by means of a competitive method that takes p-hydroxybenzoic acid as reference compound. The application of this model allows to determine the kinetic rate constants for each compound, which are correlated as a function of pH and temperature. The results obtained support that the kinetic regime of absorption is fast and pseudo-first order with respect to ozone, a condition required by the competitive method used.

Comparison of the degradation of p-hydroxybenzoic acid in aqueous solution by several oxidation processes.

A comparative study is made of 12 methods of chemical oxidation applied to degrading p-hydroxybenzoic acid in aqueous solution. The oxidation processes tested were: UV, O3, UV/TiO2, O3/Fe2+, O3/H2O2, O3/UV, UV/H2O2, H2O2/Fe2+, H2O2/Fe2+/O3, UV/H2O2/O3, H2O2/Fe2+/UV and O3/UV/H2O2/Fe2+. The 12 processes were ranked by reactivity. In a kinetic study, the overall kinetic rate constant was split up into three components: direct oxidation by UV irradiation (photolysis), direct oxidation by ozone (ozonation), and oxidation by free radicals (mainly OH*).

Kinetics of p-hydroxybenzoic acid photodecomposition and ozonation in a batch reactor.

The decomposition of p-hydroxybenzoic acid, an important pollutant present in the wastewaters of the olive oil industry, has been carried out by a direct photolysis provided by a polychromatic UV radiation source, and by ozone. In both processes, the conversions obtained as a function of the operating variables (temperature, pH and ozone partial pressure in the ozonation process) are reported. In order to evaluate the radiation flow rate absorbed by the solutions in the photochemical process, the Line Source Spherical Emission Model is used. The application of this model to the experimental results provides the determination of the reaction quantum yields which values ranged between 8.62 and 81.43 l/einstein. In the ozonation process, the film theory allows to establish that the absorption process takes place in the fast and pseudo-first-order regime and the reaction is overall second-order, first-order with respect to both reactants, ozone and p-hydroxybenzoic acid. The rate constants are evaluated and vary between 0.18x10(5) and 29.9x10(5) l/mol s depending on the temperature and pH.

A comparison of electrophysiological tests for the early diagnosis of diabetic neuropathy.

Clinical criteria and several electrophysiological parameters for detecting nerve damage were compared in 99 patients with diabetes mellitus type 1 and type 2. Abnormal results were found in sural/radial amplitude ratio (51%), minimal F-wave latency of the tibial nerve (36.4%), sensory conduction velocity of the sural nerve (29.8%), and sural sensory nerve action potential amplitude (29.3%) when pooling data from all patients and comparing them to age- and height-matched normal control subjects. Analysis of all the parameters revealed large differences between the diabetes mellitus type 1 and type 2 groups, suggesting that the type of diabetes must be taken into account when comparing the sensitivity of nerve conduction tests. In diabetes mellitus type 1, the sural/radial ratio had the clearest correlation with course of illness and was the first parameter to show a significant reduction. We conclude that the simple ratio between sural and radial amplitudes is a very sensitive parameter and abnormalities in this ratio provide the means for earliest detection of neuropathy in diabetes mellitus type 1.

Accuracy of combined clinical findings and fine needle aspiration cytology for the diagnosis in palpable breast tumors.

OBJECTIVE: A prospective study to evaluate the confidence level and predictive value of the fine needle aspiration biopsy was performed in the Oncology Service, "Hospital 20 de Noviembre, ISSSTE", Mexico City. MATERIAL AND METHODS: The cases with a palpable breast tumor, histologically confirmed who presented from 1992 to 1994 were included. One aspirate was done in each patient and these were reviewed by the same pathologist. We determined sensitivity, specificity and predictive value of the test. Age, border characteristics, size and mobility of the tumor were evaluated by Bayesian analysis. RESULTS: From 213 aspirates, 199 were elegible for diagnosis, 98 (46%) had a diagnosis of carcinoma, 13 were acellular and one suggestive. The acellular diagnoses were considered negative and suggestive positive, for analysis purposes. Mean age and tumor size were: 46.6 years (range 14-90) and 3.7 cm. (range 1-13) respectively. Sensitivity (0.932), specificity (0.973) and positive predictive value (96.9%) were estimated. We observed a high probability of true positive [P(D+/T+)] > 0.8 results in patients between 40 and 60 years of age, irregular borders, size > 2 cm and fixed lesions. CONCLUSIONS: The test has a high confidence level and in presence of two or more of the clinical factors mentioned, definitive decisions regarding treatment could be taken, without need of histologic confirmation.

Nutritional evaluation of table bread fortified with defatted soybean and sesame meals.

The nutritional value of table bread fortified with 8% defatted soybean meal (DSBM), 12% DSBM and a mixture of 8% DSBM/4% defatted sesame meal (DSM) was assessed with in vivo and in vitro tests. Fortification with DSBM and DSM decreased protein digestibilities (P < 0.05) but improved essential amino acid scores (EAA) and overall nutritional value of the breads. Fortified breads contained twice as much lysine, and consequently a better protein efficiency ratio (PER) than the control bread. The PER of the 8% DSBM/4% DSM bread was similar (P > 0.05) to the 12% DSBM bread. The 8% DSBM fortified bread showed lower PER, amino acid and protein contents than breads fortified with 12% DSBM. In vitro procedures utilized to predict protein digestibilities and PER's provided a close estimation of in vivo results obtained from growing rats.

Influence of anti-insulin antibodies on insulin immunoassays in the autoimmune insulin syndrome.

The autoimmune insulin syndrome (AIS) is a rare, benign syndrome characterized by hyperinsulinaemia and hypoglycaemia associated with the presence of autoantibodies to insulin in patients who have not been treated with insulin. We report here the case of a 52-year-old patient with recurrent attacks of severe postprandial hypoglycaemia and we also present the effect of anti-insulin antibodies on insulin immunoassays. The patient was submitted to the following diagnostic tests: 5-h oral glucose tolerance test (OGTT), a prolonged 72-h fast and an insulin tolerance test (ITT). Serum glucose, total and free insulin, C-peptide, proinsulin, insulin antibodies and other autoantibodies were measured. Insulin concentrations were measured by two methods: a double antibody radioimmunoassay (RIA) and an immunoradiometric assay (IRMA). Insulin concentration measured by RIA was extremely high in the OGTT and 72-h fast. In contrast, insulin concentrations measured by IRMA were between 120 and 888 pmol/L in the OGTT and between 37 and 133 pmol/L during the 72-h fast. Fasting free-insulin concentrations measured by RIA were between 2224 and 2669 pmol/L, whereas free-insulin concentrations measured by IRMA ranged between 93 and 237 pmol/L. Total insulin concentrations measured by RIA and IRMA were 57,615 and 94,021 pmol/L, respectively. The C-peptide concentrations were moderately high in the three tests. Serum insulin antibody concentrations were extremely high (62-71%), compared with less than 3% in normal serum samples. In conclusion, the high insulin concentrations measured by RIA were caused by insulin autoantibodies. However, insulin concentrations measured by IRMA were not influenced by them. We conclude that IRMA is the more accurate method for measuring insulin concentrations in such cases.

[Pancreatic insufficiency: an infrequent manifestation of primary hyperparathyroidism]. / Insuficiencia pancreática: una manifestación infrecuente del hiperparatiroidismo primario.

A case of malabsorption of pancreatic etiology secondary to primary hyperparathyroidism (HPT) is reported. Normalization of calcemia was achieved with parathyroidectomy and oral administration of pancreatic enzymes was initiated. HPT is an infrequent cause of pancreatic inflammatory disease. Although its association is controversial, its inclusion among the causes of exocrine pancreatic failure allows correct diagnosis and therapeutic management with a favorable prognosis.

[Heart disease in acromegaly. Study of 27 patients]. / Alteraciones cardiológicas en la acromegalia. Estudio de 27 pacientes.

BACKGROUND: The patients with acromegaly have an increased propensity to develop cardiovascular complications. The aim of this study was to evaluate the most relevant clinic, echocardiographic and Holter recording findings in acromegaly and its correlation with the growth hormone (GH) levels and duration of the disease. PATIENTS AND METHODS: 27 patients with acromegaly were evaluated. The basal levels of GH and insulin-like growth factor 1 (IGF-1) were measured at the time of cardiological study and compared with the spontaneous GH secretion during 12-24 hours previously studied. Echocardiogram was made using complete M-mode, two dimensional and spectral Doppler ultrasound mechanical system. Additionally an standard EKG and a Holter recording were performed during 24 hours. RESULTS: There was a strong correlation between basal levels of GH and integrated concentration of GH during the study of spontaneous secretion (r = 0.92; p < 0.01). The prevalence of symptomatic cardiovascular complications in this study was 49%, including 3 patients who died for cardiovascular events. The echocardiographic study showed a high prevalence of left ventricular hypertrophy (66.7%), diastolic dysfunction (63%) and impaired systolic function (18.5%). There was no correlation between GH and IGF-1 levels and echocardiographic findings. Conversely the degree of hypertrophy was related to the duration of the disease and the presence of arterial hypertension. The diastolic function only was related with the presence of hypertension. We found supraventricular arrhythmic events and malignant premature ventricular complexes in 6 and 6 patients, respectively. The EKG showed a high fiability to detect ventricular hypertrophy but no rhythm events. CONCLUSIONS: The high prevalence of cardiovascular complications in acromegaly, most of them asymptomatic, and its clinical relevance, advise the necessity to perform systematic cardiovascular evaluation in these patients.

Nosocomial infections in Spain: results of five nationwide serial prevalence surveys (EPINE Project, 1990 to 1994). Nosocomial Infections Prevalence Study in Spain.

OBJECTIVE: To determine trends in rates of nosocomial infections in Spanish hospitals. DESIGN: Prospective prevalence studies, performed yearly from 1990 through 1994. SETTING: A convenience sample of acute-care Spanish hospitals. PARTICIPANTS AND PATIENTS: The number of hospitals and patients included were as follows: 1990, 125 hospitals and 38,489 patients; 1991, 136 and 42,185; 1992, 163 and 44,343; 1993, 171 and 46,983; 1994, 186 and 49,689. A core sample of 74 hospitals, which participated in all five surveys and included a mean of 23,871 patients per year, was analyzed separately. RESULTS: The overall prevalence rate of patients with nosocomial infections in the five studies was as follows: 1990, 8.5%; 1991, 7.8%; 1992, 7.3%; 1993, 7.1%; and 1994, 7.2%. The prevalence rate of patients with nosocomial infection in the core sample of 74 hospitals was 8.9%, 8.0%, 7.4%, 7.6%, and 7.6%, respectively (test for trend, P = .0001). Patients admitted to intensive-care units had a 22.8% prevalence rate of nosocomial infection in 1994. The most common nosocomial infections by primary site were urinary tract infection and surgical site infections, followed by respiratory tract infections and bacteremia. More than 60% of all infections were supported by a microbiological diagnosis. CONCLUSIONS: The EPINE project provides a uniform tool for performing limited surveillance of nosocomial infections in most Spanish acute-care hospitals. Its use helps to spread an accepted set of definitions and methods for nosocomial infection control in the Spanish healthcare system. The surveys indicated that the prevalence of nosocomial infections has been reduced over the last 5 years in a core sample of Spanish hospitals.