Continuous thermal hydrolysis and energy integration in sludge anaerobic digestion plants.

A thermal hydrolysis pilot plant with direct steam injection heating was designed and constructed. In a first period the equipment was operated in batch to verify the effect of sludge type, pressure and temperature, residence time and solids concentration. Optimal operation conditions were reached for secondary sludge at 170 degrees C, 7 bar and 30 minutes residence time, obtaining a disintegration factor higher than 10, methane production increase by 50% and easy centrifugation In a second period the pilot plant was operated working with continuous feed, testing the efficiency by using two continuous anaerobic digester operating in the mesophilic and thermophilic range. Working at 12 days residence time, biogas production increases by 40-50%. Integrating the energy transfer it is possible to design a self-sufficient system that takes advantage of this methane increase to produce 40% more electric energy.

Development and implementation of an expert system to improve the control of nitrification and denitrification in the Vic wastewater treatment plant.

Wastewater treatment plants employ various physical, chemical and biological processes to reduce pollutants from raw wastewater. One of the most important is the biological nitrogen removal process through nitrification and denitrification steps taking place in various sections of the biological reactor. One of the most extensively used configurations to achieve the biological nitrogen removal is an activated sludge system using oxidation ditch or extended aeration. To improve nitrogen removal in the wastewater treatment plant (WWTP) of Vic (Catalonia, NE Spain), the automatic aeration control system was complemented with an Expert System to always provide the most appropriate aeration or anoxia sequence based on the values of ammonium and nitrates given by an automatic analyzer. This article illustrates the development and implementation of this knowledge-based system within the framework of a Decision Support System, which performs SCADA functions. The paper also shows that the application of the decision support system in the Vic WWTP resulted in significant improvements to the biological nitrogen removal.

Disease expression and molecular genotype in congenital adrenal hyperplasia due to 21-hydroxylase deficiency.

Genotyping for 10 mutations in the CYP21 gene was performed in 88 families with congenital adrenal hyperplasia due to 21-hydroxylase deficiency. Southern blot analysis was used to detect CYP21 deletions or large gene conversions, and allele-specific hybridizations were performed with DNA amplified by the polymerase chain reaction to detect smaller mutations. Mutations were detected on 95% of chromosomes examined. The most common mutations were an A----G change in the second intron affecting pre-mRNA splicing (26%), large deletions (21%), Ile-172----Asn (16%), and Val-281----Leu (11%). Patients were classified into three mutation groups based on degree of predicted enzymatic compromise. Mutation groups were correlated with clinical diagnosis and specific measures of in vivo 21-hydroxylase activity, such as 17-hydroxyprogesterone, aldosterone, and sodium balance. Mutation group A (no enzymatic activity) consisted principally of salt-wasting (severely affected) patients, group B (2% activity) of simple virilizing patients, and group C (10-20% activity) of nonclassic (mildly affected) patients, but each group contained patients with phenotypes either more or less severe than predicted. These data suggest that most but not all of the phenotypic variability in 21-hydroxylase deficiency results from allelic variation in CYP21. Accurate prenatal diagnosis should be possible in most cases using the described strategy.

Insulin insensitivity in adrenal hyperplasia due to nonclassical steroid 21-hydroxylase deficiency.

To determine whether hyperandrogenism caused by an inborn error of adrenal steroidogenesis could produce insulin resistance, we examined insulin sensitivity in females with 21-hydroxylase deficiency. Minimal modelling was used to analyze the results of tolbutamide-modified, frequently sampled, iv glucose tolerance testing. Insulin sensitivity [Si; (min-1) (microU/mL)-1] was plotted against body mass index (BMI; defined as kilograms per m2). Six patients with nonclassical 21-hydroxylase deficiency (mean age, 27 yr; mean BMI, 23.2) underwent testing. None of these patients was in active puberty, nor was any patient being treated with glucocorticoids at the time of the study. Twelve eumenorrheic nonhyperandrogenic young adult female control subjects (mean age, 27 yr; mean BMI, 22.4) were also tested. The basal 17-hydroxyprogesterone concentration, but not the total serum testosterone level, was significantly different in the two groups (mean +/- SEM, 11,987 +/- 2,761 vs. 4,059 +/- 802 pmol/L; P < 0.05). As a group the patients' Si values were significantly lower than those of the controls (mean +/- SEM, 4.1 +/- 0.6 vs. 9.7 +/- 1.2; P < 0.05). There was no correlation between Si and basal serum 17-hydroxyprogesterone, testosterone, delta 4-androstenedione, or dehydroepiandrosterone. We conclude that chronic hypersecretion of androgen precursors due to an inborn error of metabolism can induce a reduction in insulin sensitivity.

LDL from aerobically-trained subjects shows higher resistance to oxidative modification than LDL from sedentary subjects.

We studied the effect of regular intense aerobic exercise on the LDL susceptibility to oxidation and the electronegative LDL-proportion (LDL(-)). A group of 38 well-trained athletes was compared to a group of 38 age-BMI-matched sedentary individuals. Athletes showed higher concentration of total cholesterol (athletes 5.08 +/- 0.70 versus controls 4.65 +/- 0.75 mmol/l, P = 0.0229) and HDL cholesterol (athletes 1.72 +/- 0.47 versus controls 1.46 +/- 0.39 mmol/l, P = 0.0068); total plasma triglyceride, LDL cholesterol and VLDL cholesterol did not differ between trained and untrained subjects. The susceptibility of LDL to oxidation, determined by conjugated dienes formation and expressed as lag phase, was lower in athletes than in sedentaries (trained subjects 47.0 +/- 5.6 versus sedentary subjects 41.9 +/- 5.0 min, P = 0.0002). LDL(-) was similar in both groups (athletes 10.32 +/- 4.70 versus controls 10.26 +/- 3.71%). The antioxidant content in total plasma and isolated LDL (alpha-tocopherol, retinol, lycopene, alpha-carotene and beta-carotene) was quantitated by HPLC in a subgroup of 32 athletes and 32 control subjects. Athletes showed higher amounts of alpha-tocopherol and retinol in plasma, but not in LDL. However, none of these antioxidants correlated with the lag phase time. Trained subjects showed lower prevalence of smoking. However, no differences were observed between smokers and non-smokers concerning lag phase. No significant difference between athletes and sedentaries concerning LDL density, or composition was observed. We conclude that LDL from trained subjects is more resistant to oxidative modification than LDL from sedentary subjects. This observation could not be attributed to conventional antioxidants as alpha-tocopherol and carotene content of LDL was unchanged in trained subjects. Thus, although none of the variables studied appear as a single predictor of the LDL susceptibility to oxidation, an additive effect of the antioxidant content, the presence of some undetermined co-antioxidant, HDL and/or smoking habits cannot be discarded as responsible for the increased resistance to oxidation of LDL in trained subjects.

Marathon runners presented lower serum cholesteryl ester transfer activity than sedentary subjects.

Acute exercise promotes raised HDL cholesterol concentrations by lipolysis stimulation, but this effect is insufficient to explain the more permanent HDL increases seen during regular exercise. During training periods in a group of marathon runners, we measured lipid transfer protein I (LTP-I)-mediated cholesteryl ester transfer activity (CETA) and its relationship to their HDL concentrations. Runners of both sexes showed significantly lower CETA values than those of sedentary controls. Male runners also had significantly lower serum concentrations of triglyceride, VLDL cholesterol and apolipoprotein B, and significantly higher concentrations of HDL cholesterol and apolipoprotein A-I than male controls. Results indicate that regular practice of aerobic exercise promotes modifications of lipoprotein metabolism related not only to lipolysis, but also to lower CETA. Such modifications are associated with reduced risk of atherosclerosis.

Increase of LDL susceptibility to oxidation occurring after intense, long duration aerobic exercise.

The effect of heavy, long duration aerobic exercise on low density lipoprotein (LDL) susceptibility to oxidation and on distribution of LDL subfractions was studied. Six well-trained runners, previously fasted, ran continuously for 4 h. Controlled intake of liquid and food was permitted during exercise. Total plasma and LDL triglyceride increased significantly. LDL susceptibility to oxidation, measured as conjugated dienes formation, was modified significantly (P < or = 0.05) after running (14% reduction in lag phase time, and 8% increase in maximal curve slope). The percentage of electronegative LDL form (named LDLB) also increased significantly (P < or = 0.05) after exercise both basally (from 7.3% to 11%) and after 2h of induced oxidation (from 40.6% to 52.3%). Neither LDL susceptibility to oxidation nor increase of LDLB was statistically associated with food consumed during the race or modifications of triglycerides suggesting that this effect was due to exercise rather than food-related. The pattern of LDL subfractions was type A in all athletes before and after running. The oxidative LDL changes, seen in exercise conditions similar to those of hard training or competition, demonstrated an unfavourable effect of very intense exercise on lipoprotein metabolism.

Apolipoprotein E phenotypes, lipoprotein composition, and xanthelasmas.

The different types of serum lipoproteins, including apolipoprotein E phenotypes, were measured in 50 patients with xanthelasma. Half of them were found to be hyperlipemic. The normolipemic and hyperlipemic groups with xanthelasma were compared with two control groups (one a group of normolipemic patients and another a group of hyperlipemic patients without xanthelasma) selected as homogeneously as possible with regard to age, sex, degree of obesity, and hyperlipemic phenotype. The only significant differences found among the groups, regardless of the presence of hyperlipemia, were the increased levels of total and high-density lipoprotein phospholipids, and lower levels of apolipoprotein B, found in the group with xanthelasmas. The distribution of apolipoprotein E phenotypes was the same in both groups, with slight differences between the normolipemic and hyperlipemic groups. Patients with xanthelasmas showed slight deviations in the metabolism of lipoproteins that require further clarification.

Lipoprotein compositional abnormalities in type I diabetes: effect of improved glycaemic control.

Major lipoprotein mass and composition were assessed in 45 subjects with insulin dependent diabetes mellitus (IDDM), before and after 2 months of intensive insulin therapy (IIT) and in 40 healthy control subjects. As compared to the control group, diabetic subjects at baseline had higher low density lipoprotein (LDL) and lower high density lipoprotein (HDL) masses. Expressing each lipoprotein constituent as a percent of total lipoprotein mass, very low density lipoprotein (VLDL) of diabetic patients was enriched in cholesterol and phospholipid and depleted in triglyceride and protein; IDL had higher triglyceride and phospholipid and lower cholesterol and protein proportion; LDL was depleted in protein and enriched in triglyceride; HDL was depleted in protein and enriched in triglyceride, cholesterol and phospholipid. After 2 months of IIT, HbA1c fell from 10.3 +/- 2 to 7.5 +/- 2% (P < 0.0001) and so did VLDL mass, which was lower than in control subjects. In addition, LDL and HDL masses, as well as triglyceride and cholesterol proportion in IDL particles normalized. The other compositional abnormalities improved without complete normalization. Thus, intensive insulin therapy in IDDM subjects brought quantitative lipoprotein alterations to normal even subnormal range, while most of the composition abnormalities improved without reaching complete normalization.

Using mathematical morphology to determine left ventricular contours.

The aim of this study is to investigate the use of mathematical morphology for the determination of left ventricular contours in scintigraphic images using multigated radionuclide angiography. We have developed a completely automatic method that first restores the image with a Wiener filter, then finds the region where the left ventricle is contained, and finally segments the left ventricle contour and a background zone. The contours depend on the values of the parameters that appear in the mathematical morphology method, which are related to the height and the slope of the count distribution. Results obtained with this method are compared with the contours and the background zones outlined by experts on the basis of the number of counts. We study the values of the parameters with which the optimum correlation is obtained.

[Bonded amalgams. An important change in operatory dentistry]. / Amalgamas adheridas. Un importante cambio en operatoria dental.

The incorporation of new adhesives which are able to bond amalgam to the dental structure means a hopeful and encouraging advance in Operative Dentistry. The present study has been done from the point of view of the general practitioner, and lets us check the efficacy of the bonded amalgam and compare it with the techniques and materials traditionally used.

Failure of steroid replacement to consistently normalize pituitary function in congenital adrenal hyperplasia: hormonal and MRI data.

Exogenous glucocorticoid replacement in patients with congenital adrenal hyperplasia (CAH), who due to an adrenal 21-hydroxylase enzyme deficiency are unable to produce endogenous glucocorticoids, is aimed at normalizing hypothalamic-pituitary-adrenal function. Excess androgen production by the adrenals is thus decreased. Despite standard glucocorticoid replacement doses (12.5-40 mg, 10.5-27 mg/m2/day hydrocortisone equivalents) 4 of 7 patients ranging in age from 14 to 33 years had abnormalities of the pituitary on MRI. Three appeared to have microadenomas and 1 had an empty sella. Five (3 salt wasters, 2 simple virilizers) of these 7 patients had 60-min p.m. ovine corticotropin-releasing hormone (oCRH) stimulation studies. The mean (logarithm) area under the ACTH curve for 0-60 min after oCRH stimulation was significantly greater in patients than controls (p < 0.0001). Mean ACTH at each time point before and after oCRH stimulation was similarly greater in patients than controls (p < 0.05). Two of these patients had pituitary microadenomas, 1 had an empty sella; all 3 were salt wasters. Despite standard glucocorticoid replacement, adolescent and young adult patients with CAH tend to have high basal ACTH and ACTH hyperresponsiveness to oCRH, as well as structural abnormalities of the pituitary. The inevitable periods of under- and overexposure to glucocorticoids in CAH patients may over time cause abnormalities of the hypothalamic-pituitary-adrenal axis.

Apolipoprotein C subtype distribution in type 2 diabetes mellitus.

Plasma lipid levels and apolipoprotein C (apo C) composition of VLDL were investigated in a group of Type 2 diabetic patients at first attendance at the outpatient clinic and before any therapeutic intervention. Patients were distributed into two groups of 26 individuals, normo- and hyperlipidaemic, respectively, and compared with two matched control groups. Normolipidaemic diabetic patients had higher serum triglycerides, VLDL cholesterol, and lower HDL cholesterol than matched normolipidaemic control subjects. While hyperlipidaemic non-diabetic individuals showed increased apo C II and decreased apo C III-1 percentages when compared with normolipidaemic non-diabetic individuals (12.1 +/- 4.9 vs 8.5 +/- 3.2% and 44.0 +/- 6.7 vs 48.1 +/- 7.0%, respectively, mean +/- SD, both with p less than 0.05), the relative distribution of apo C III isoforms and apo C II was similar in both normo- and hyperlipidaemic diabetic patients.

Plasma immunoreactive somatostatin is elevated in diabetic ketoacidosis and correlates with plasma non-esterified fatty acid concentration.

In experimental diabetes and after the administration of beta-hydroxybutyrate and non-esterified fatty acids (NEFA), an increase in circulating immunoreactive somatostatin (IRS) has been described. Both ketones and NEFA are raised in diabetic ketoacidosis. Therefore, we decided to investigate 10 patients in diabetic ketoacidosis by measuring, on admission and throughout the initial 24 hours of therapy, circulating levels of IRS, beta-hydroxybutyrate, acetoacetate, triglycerides, blood glucose, pH and NEFA. Fluids and insulin were administered IV following a previously established protocol. Nine patients showed abnormally high levels of circulating IRS. When compared with a group of controlled insulin-dependent diabetic patients, basal IRS was high (111 +/- 15 vs 28 +/- 3 pmol/l), and remained elevated for at least 24 h despite clear improvement of metabolic status. On admission we also found elevated levels of NEFA (1.04 +/- 0.2 mmol/l), triglycerides (4.7 +/- 1.1 mmol/l), beta-hydroxybutyrate (22.1 +/- 4mmol/l), and acetoacetate (4.8 +/- 1.1 mmol/l). A significant correlation was found initially between IRS and NEFA (p less than 0.01). We conclude that circulating IRS is high in most cases of diabetic ketoacidosis. The mechanism behind this hypersomatostatinaemia could be related to the abnormalities of lipid metabolism which occur in diabetic ketoacidosis.

Quick method of determining lipoproteins, including those of intermediate density, in serum.

We describe an ultracentrifugation method for isolating the different lipoprotein classes relatively quickly. In this method the very-low-density lipoproteins are first separated by non-density-adjusted ultracentrifugation. The resulting infranatant material is then stained with Coomassie Brilliant Blue R-250 and ultracentrifuged in a density gradient. The intermediate-density lipoproteins (IDL), low-density lipoproteins, and high-density lipoproteins fractions are separated by aspiration from the top of the tube. This method can be used to separate, analyze, and quantify lipoproteins, including anomalous lipoproteins such as the IDL. The CVs for the present method never exceeded 15%.

Analytical and clinical performance of an automated immunoassay system (Immulite) for estradiol in serum.

The analytical and clinical performance of a commercial automated immunoassay system (Immulite) for estradiol (E2) in serum was evaluated. The functional sensitivity for E2 was 0.07 nmol/l, and analytical imprecision (<13%, <9% and <7% at 0.22, 0.51 and 1.51 nmol/l, respectively) for concentrations above this detection limit met published analytical goals. The assay recovery was good and the assay was linear over a wide concentration range. No sample carryover was found, and interferences from common substances present in serum were observed only at very high concentrations. Most of samples from men and postmenopausal women showed E2 concentrations below the detection limit. Longitudinal estradiol profiles from 11 healthy menstruating women showed characteristic menstrual cycle patterns (12 samples per subject obtained during a 30-day period). Longitudinal studies on women during induction of ovulation showed that E2 concentrations are highly correlated with the total number of follicles. Our results demonstrate the reliability of this system for routine use in the clinical laboratory.