Environment and Spatial Influences on Aquatic Insect Communities in Cerrado Streams: the Relative Importance of Conductivity, Altitude, and Conservation Areas.

The aquatic insect community is an important element for stream functionality and diversity, but the effects of altitude and conservation areas on the aquatic insect community have been poorly explored in neotropical ecozone. The lack of studies about the relative importance of space and environment on community structure is another obstacle within aquatic insect ecology, which precludes the inclusion of these studies in more current frameworks, like the metacommunity dynamics. We evaluated the relationship between the aquatic insect community structure at 19 streams in the Brazilian Cerrado and spatial and environmental variables, namely geographical distance among sites, stream altitude, chemical variables, and environmental protection areas. We partitioned the variance explained by spatial and environmental components using a partial redundancy analysis. The environment exhibited a strong spatial structure for abundance and number of genera, increasing these community parameters with elevated water conductivity. Only community composition had a large unexplained portion of variance, with a small portion constrained by environmental (altitude and conductivity) and spatial factors. A relevant point in the result was the streams with high conductivity were located outside of the conservation areas. These results suggest that the relationship between number of genera and abundance with environmental conditions is always associated with spatial configuration of streams. Our study shows that altitude is an important determinant of community structure, as it exerts indirect influences, and electrical conductivity directly determines community composition, and that some national parks may be inefficient in maintaining the diversity of aquatic insects in the Cerrado region.

Functional Process Zones Characterizing Aquatic Insect Communities in Streams of the Brazilian Cerrado.

Stream ecology studies see to understand ecological dynamics in lotic systems. The characterization of streams into Functional Process Zones (FPZ) has been currently debated in stream ecology because aquatic communities respond to functional processes of river segments. Therefore, we tested if different functional process zones have different number of genera and trophic structure using the aquatic insect community of Neotropical streams. We also assessed whether using physical and chemical variables may complement the approach of using FPZ to model communities of aquatic insects in Cerrado streams. This study was conducted in 101 streams or rivers from the central region of the state of Goiás, Brazil. We grouped the streams into six FPZ associated to size of the river system, presence of riparian forest, and riverbed heterogeneity. We used Bayesian models to compare number of genera and relative frequency of the feeding groups between FPZs. Streams classified in different FPZs had a different number of genera, and the largest and best preserved rivers had an average of four additional genera. Trophic structure exhibited low variability among FPZs, with little difference both in the number of genera and in abundance. Using functional process zones in Cerrado streams yielded good results for Ephemeroptera, Plecoptera, and Trichoptera communities. Thus, species distribution and community structure in the river basin account for functional processes and not necessarily for the position of the community along a longitudinal dimension of the lotic system.

Mephedrone ("bath salt") pharmacology: insights from invertebrates.

Psychoactive bath salts (also called meph, drone, meow meow, m-CAT, bounce, bubbles, mad cow, etc.) contain a substance called mephedrone (4-methylcathinone) that may share psychostimulant properties with amphetamine and cocaine. However, there are only limited studies of the neuropharmacological profile of mephedrone. The present study used an established invertebrate (planarian) assay to test the hypothesis that acute and repeated mephedrone exposure produces psychostimulant-like behavioral effects. Acute mephedrone administration (50-1000 µM) produced stereotyped movements that were attenuated by a dopamine receptor antagonist (SCH 23390) (0.3 µM). Spontaneous discontinuation of mephedrone exposure (1, 10 µM) (60 min) resulted in an abstinence-induced withdrawal response (i.e. reduced motility). In place conditioning experiments, planarians in which mephedrone (100, 500 µM) was paired with the non-preferred environment during conditioning displayed a shift in preference upon subsequent testing. These results suggest that mephedrone produces three behavioral effects associated with psychostimulant drugs, namely dopamine-sensitive stereotyped movements, abstinence-induced withdrawal, and environmental place conditioning.

Chemiluminescent determination of xanthine oxidase activity in milk.

A chemiluminescent method for determining xanthine oxidase (XOD) activity was developed and applied to the assay of milk enzyme activity using a photomultiplier luminometer. Various kinds of milk and cream samples were analysed for XOD content. In pasteurized milk, XOD activity depended on the fat content and in UHT milk it disappeared owing to the heat treatment. Milk sample preparation was very simple, requiring only homogenization at 40 degrees C followed by a 1:10 dilution with UHT ('XOD-free') milk. The assay was carried out at 25 degrees C. The response obtained from XOD standard solutions in milk was linear from 0.1 to 500 enzyme units (U) l-1, but for the actual milk samples values ranged only from 1 to 135 U l-1. The detection limit at 2 SD was 0.1 U l-1 in milk, while in buffer it was 100 times lower. The intra-assay and interassay CV for XOD activity in milk were 6-12%.

Blood zinc status and zinc treatment in human immunodeficiency virus-infected patients.

We investigated the zinc concentration in blood and the effect of zinc supplementation in 11 male outpatients seropositive for human immunodeficiency virus at stage 5 according to the Walter Reed classification. Zinc concentration was measured in serum, platelets, mononuclear and polymorphonuclear cells, and erythrocytes. There was a significant increase in serum zinc concentration after zinc administration, but the zinc level in blood cells remained unchanged. All patients showed a progressive gain in body weight and a slight elevation in levels of CD4+ cells. No adverse side-effects were noticed.

Development of a sensitive, direct luminescent enzyme immunoassay for plasma estradiol-17 beta.

A rapid, sensitive, precise, chemiluminescent enzyme immunoassay for estradiol-17 beta has been developed and validated. Antibodies were produced in rabbits using estradiol-17 beta-6-(O-carboxymethyl)oxime coupled to bovine serum albumin, purified and immobilized on polystyrene beads (6.4 mm diameter). The same derivative was used to prepare the enzymatic tracer by coupling with horseradish peroxidase. The assay, direct on the serum sample, featured a 4-h binding step at 4 degrees C followed by the chemiluminescent detection using luminol/H2O2. The detection limit was 0.15 pg/tube and the assay was carried out on 20-100 microliter of sample, allowing measurement of estradiol-17 beta in plasma concentrations from 1.5 to 500 pg/ml. The method fulfills all the standard requisites of precision and accuracy and the results agree well with a radioimmunoassay procedure on extracted serum.

Hereditary nonspherocytic hemolytic anemia due to a new hexokinase variant with reduced stability.

A 27-year-old woman with severe chronic hemolytic anemia was found to have reduced red cell hexokinase activity when the degree of reticulocytosis was considered. This enzyme had normal pH-dependent activity, normal Km for glucose, fructose, and mannose, normal Km for Mg adenosine triphosphate (ATP)2- and Ki for glucose-1,6-diphosphate. Furthermore, the pH-dependence and orthophosphate dependence of Ki for glucose-1,6-diphosphate were normal. However, this hexokinase was inactivated rapidly at 44 degrees C. No abnormalities were found in the red cell hexokinase isozymic pattern when it was compared with the profile obtained from cells of similar age. The hexokinase specific activity was reduced in all the red blood cell fractions obtained by density gradient ultracentrifugation; a marked difference in the distribution of cells through the gradient was evident. Among the glycolytic intermediates, a significant decrease of 2,3-diphosphoglycerate was evident. ATP and glucose 6-phosphate were also reduced when compared with cells of similar. Glucose consumption of the hexokinase-deficient cells decreased, but the rate of glucose metabolized through the hexose monophosphate shunt was unchanged. Although the total hexokinase activity in lymphocytes was only reduced by 37%, a marked hexokinase deficiency was detected in blood platelets (20% to 25% of normal activity). The parents and one of two siblings of the patient were heterozygous for the defect, with 66% to 74% of normal erythrocyte hexokinase activity and reduced heat stability of the enzyme. These results, when compared with those obtained in previously reported cases of hexokinase deficiency, provide further evidence of the broad phenotypic variability that characterizes this disorder. Furthermore, it is suggested that failure of energy generation is probably the primary cause of hemolytic anemia in hexokinase deficiency.

Development of a sensitive enzyme immunoassay for plasma and salivary steroids.

The development of an enzyme-labelled immunoassay (EIA) of sufficient range and sensitivity for determination of plasma and salivary steroids is described. The method is based on competition in the solid phase. A fixed amount of a specific antibody is immobilized on polystyrene beads, its amount being enough to bind about 50% of a steroid-enzyme conjugate (covalently linked steroid Jhorseradish peroxidase conjugate). The initial incubation at 25 degrees of serum sample or extract with the conjugate in presence of the immobilized antibody is followed by washing and the addition of a substrate for measurement of the enzyme activity either colorimetrically by the H(2)O(2)/o-phenylenediamine method or by the luminescence reaction based on the use of H(2)O(2)/luminol. The method is precise and accurate (CV < 10% for both the intra- and inter-assay studies). The sensitivity of the colorimetric determination is similar to that of radioimmunoassay, but the luminescence method is more sensitive. Radioimmunoassay and EIA gave results in good agreement (r > 0.97). The method has also been applied to salivary steroids: the procedure is direct and only a few mu1 of saliva are required. The levels of these steroids in saliva are only about a tenth of those in serum but directly correlated with them (r > 0.85). The enzyme immunoassay proposed is sensitive and precise enough to measure these steroids accurately in saliva and plasma.

Defective intrinsic fibrinolytic activity in a patient with severe factor XII-deficiency and myocardial infarction.

The paper reports the occurrence of myocardial infarctions in a patient with severe deficiency of blood coagulation factor XII (Hageman factor). Factor XII plays a central role in the intrinsic activation of fibrinolysis and consequently the defective intrinsic fibrinolytic activity detected in the present case casts some doubt on its role in the increased vulnerability to thrombotic accident.

ELISA for salivary and plasma estriol in pregnancy.

A competitive, sensitive, and rapid enzyme-linked immunoadsorbent assay (ELISA) was developed for the determination of estriol in saliva and in plasma. Horseradish peroxidase (HRP) was used as the label enzyme; separation between free and bound steroid was carried out by insolubilized antibody prepared by adsorbing purified IgG of rabbit anti-6-oxoestriol-6-(O-carboxymethyl)oxime-BSA on polystyrene balls. The enzyme activity was measured by a colorimetric reaction using o-phenylenediamine dihydrochloride and hydrogen peroxide as substrate. The sensitivity of the assay was 12 pg/tube. In order to compare ELISA to RIA estriol estimations in different biological fluids, we selected six women during normal pregnancy, from the 30th to the 40th week of gestation. Salivary estriol was assayed by direct and extraction methods, while the corresponding plasma samples of the same subjects were analyzed only for unconjugated estriol by an extraction method. A good agreement was found between the results obtained by RIA and ELISA: r = 0.897, p less than 0.001 between direct RIA and direct ELISA in saliva; r = 0.909, p less than 0.001 between extraction RIA and direct ELISA in saliva; and r = 0.916, p less than 0.001 between extraction RIA and extraction ELISA in plasma. A good correlation (r = 0.793, p less than 0.001) was present between plasma samples by RIA and saliva samples by ELISA (direct method). These results indicate that: ELISA is a reliable method for the determination of estriol in plasma and saliva. Saliva samples can be used for the assay of estriol and therefore for the assessment of fetal conditions during pregnancy.

Androstenedione metabolism in human uterine tissues: endometrium, myometrium and leiomyoma.

Androstenedione was metabolized in vitro by human endometrium, myometrium and leiomyoma, to its 5 alpha-reduced metabolites: 5 alpha-androstan-3,17-dione (5 alpha-androstanedione) and androsterone as well as to testosterone, 17 beta-hydroxy-5 alpha-androstan-2-one (5 alpha-DHT) and 5 alpha-androstan-3 alpha,17 beta-diol (3 alpha-diol). Uterine tissue showed a similar enzymatic profile to the androgen responsive tissues; these data suggest that androgens may have a functional role in the uterine pathophysiology.

Radioimmunoassay of three oestrogens and three androgens in the same plasma sample after extraction and chromatographic separation.

The plasma levels of oestrone (Oe1), 17 beta-oestradiol (Oe2), oestriol (Oe3), testosterone (T), 5 alpha-dehydrotestosterone (DHT) and androstenedione (A) were assayed by RIA in plasma obtained from peripheral venous blood. The hormones are isolated from the plasma extract, first by Sephadex LH-20 column chromatography (Oe2/Oe3/Oe1, T, DHT, A) and after Oe1, T, DHT, A by TLC on silica gel 60 F254. The accuracy, reproducibility and sensitivity of the method make it satisfactory for clinical studies.

Heroin addiction: relationship between the plasma levels of testosterone, dihydrotestosterone, androstenedione, LH, FSH, and the plasma concentration of heroin.

Changes in sexual function and hormone levels are commonly found in subjects addicted to narcotics. In this study we examined 16 male and 3 female addicts who had been taking heroin (H) in the last year in doses higher than 150 mg/day. In these patients, who presented similar clinical problems, we assayed by RIA the plasma levels of heroin, testosterone, (T), dihydrotestosterone (DHT), androstenedione (A), luteinizing hormone (LH) and follicle-stimulating hormone (FSH) for periods of 150 min, 6 h and 9 h. We found a significant reduction of T and DHT concomitant with higher plasma concentrations of heroin but no relevant changes of A, LH and FSH. T and DHT returned to the initial levels after the decrease of heroin concentration. The GnRH test effectd on a female subject allowed us to make the diagnosis of hypothalamic amenorrhea. In the same patient no circadian rhythms for T, DHT and A were detected.

Further studies on pulmonary oedema of high altitude. Abnormal responses to hypoxia of men who had developed pulmonary oedema at high altitude.

101 Indian soldiers, 57 of whom had developed pulmonary oedema of high altitude (POHA) and 44 who had not developed this condition in spite of being at high altitudes for over 2 years, were investigated for observing the differences, if any, in their reaction to acute hypoxic stress. Each subject was made to breathe a 10% hypoxic mixture for 5 min. Haemodynamic parameters like pulmonary artery pressure (systolic, diastolic and mean), brachial artery pressure, wedge pressure, cardiac output, minute ventilation, arterial oxygen saturation and oxygen uptake before and at the end of hypoxic breathing were estimated. In addition, results of the cold pressor test were recorded and the Vd/Vt ratio was estimated. The results obtained in the present study confirmed those obtained in our previous studies. In addition, it was observed that oxygen uptake was significantly higher and oxygen saturation lower after hypoxia in the POHA subjects than in the controls. Certain parameters for screening of subjects possibly susceptible to POHA have been suggested.

[Carcadian variations of plasma delta4-androstenedione in normal and castrated adult males].

The plasma concentration of delta4-androstenedione has been assayed by a radioimmunological method, preceded by chromatographic purfication, in 11 normal adult and 4 adult castrated males at various times of day. The circadian variations observed are critically evaluated.

Significance of 17alpha OH progesterone assay in the evaluation of ovarian and adrenal function.

Plasma 17alpha OH progesterone was assayed radioimmunologically, using an anti-17-OH-progesterone BSA antiserum as specific binding antigen. The method consisted in extracting steroids with ethyl ether from 1 ml plasm (to which 17alpha OH progesterone-1,2-3H had been added for the assessment of losses); the extract was then submitted to chromatography on a Sephadex LH-20 column, antiserum was added and the free steroid was separated from the bound form by Charcoal-dextran. Average recovery of 17alpha OH progesterone-1,2-3H was 75+/-5%. Minimum sensitivity of the method oscillated about 7-10 pg. MIF (Method Interfering Factors) were evaluated. The method was used for the assay of 17alpha OH progesterone plasma levels during normal menstrual cycles, in women undergoing ovarian stimulation with HMG and HCG in the follicular and luteal phase respectively. Finally, changes of plasma 17alpha OH progesterone levels were assessed during adrenal stimulation and suppression in various stages of the menstrual cycle.