High frequency of genital carriers of Leptospira sp. in sheep slaughtered in the semi-arid region of northeastern Brazil.

Although some studies in sheep have indicated leptospire colonization of the genital tract, further studies are needed to clarify the role of genital carriers in this species. Thus, this study aimed to evaluate the colonization of pathogenic leptospires in the genital and urinary tract of slaughtered sheep. Fifty-seven adult, female woolless sheep destined for slaughter were used. Renal (n = 57), bladder (n = 57), ovary (n = 34), uterine tube (n = 44), and uterus (n = 33) samples were collected for molecular detection of Leptospira sp. DNA, and blood samples (n = 57) for serological testing. The molecular testing was performed using polymerase chain reaction (PCR), and the serological testing was performed using microscopic serum agglutination test (MAT). Samples with amplifying DNA were subjected to genetic sequencing. In total, leptospiral DNA was found in the tissues of 44 (77.2%) sheep, whereas only nine animals were positive on both PCR and MAT; there was slight agreement between PCR and MAT techniques (k = 0.0268; p = 0.684). In 61 (54.9%) genital tract and in five (4.4%) urinary tract samples, the leptospiral DNA was detected, with significant difference (p < 0.001). The genes of one sample from the uterine tube and another from the bladder were sequenced and demonstrated 99% similarity to Leptospira interrogans. Anti-Leptospira antibodies were detected in 11 (19.3%) of the tested animals. The results reinforce the importance of the genital tract as an extra-renal site of colonization, suggesting the possibility of venereal transmission in sheep.

Spatial patterns of the leaf crown borer Eupalamides cyparissias (Cramer, 1775) (Lepidoptera: Castiniidae) in coconut (Cocos nucifera L.) tropical region.

The leaf crown borer Eupalamides cyparissias (Cramer, 1775) is an important pest of coconut (Cocos nucifera L.) and other palms (Arecaceae) of economic importance, attacking the base of leaves, inflorescences, and infructescences, increasing fruit abortion. The objective of this study was to evaluate the spatial correlation of the infestation rate of E. cyparissias in coconut plantation blocks in the Brazilian Amazon, from January to December 2019, in the city of Santa Izabel, Pará, Brazil. The study area is a farm subdivided into 157 blocks of a commercial plantation of the green dwarf coconut. The Local Moran's Index was used to evaluate the existence of spatial autocorrelation of the E. cyparissias infestation rate in the 157 blocks with neighboring blocks. The infestation rate was calculated by the ratio between the number of plants attacked by the borer and the total number of plants in a block. There is a significant correlation of the symptomatology of the attack by E. cyparissias in the blocks of the experimental area, which indicates an aggregated pattern of distribution. There is no significant correlation between the attack by the borer and the age of the coconut tree; however there is a significant correlation between the attack by the borer and proximity to forest areas. These results indicate that forest regions are foci of infestation by the borer in coconut plantations.

A Systems Approach to Remediating Human Exposure to Arsenic and Fluoride From Overexploited Aquifers.

In semiarid agricultural regions, aquifers have watered widespread economic development. Falling water tables, however, drive up energy costs and can make the water toxic for human consumption. The study area is located in central Mexico, where arsenic and fluoride are widely present at toxic concentrations in well water. We simulated the holistic outcomes from three pumping scenarios over 100 years (2020-2120); (S1) pumping rates increase at a similar rate to the past 40 years, (S2) remain constant, or (S3) decrease. Under scenario S1, by 2120, the depth to water table increased to 426 m and energy consumption for irrigation increased to 4 × 109 kWh/yr. Arsenic and fluoride concentrations increased from 14 to 46 µg/L and 1.0 to 3.6 mg/L, respectively. The combined estimated IQ point decrements from drinking untreated well water lowered expected incomes in 2120 by 27% compared to what they would be with negligible exposure levels. We calculated the 100-year Net Present Value (NPV) of each scenario assuming the 2020 average crop value to water footprint ratio of 0.12 USD/m3. Without drinking water mitigation, S1 and S3 yielded relative NPVs of -5.96 × 109 and 1.51 × 109 USD, respectively, compared to the base case (S2). The relative NPV of providing blanket reverse osmosis treatment, while keeping pumping constant (S2), was 11.55 × 109 USD and this gain increased when combined with decreased pumping (S3). If a high value, low water footprint crop was substituted (broccoli, 1.51 USD/m3), the net gains from increasing pumping were similar in size to those of implementing blanket drinking water treatment.

Sperm chromatin integrity in DDT-exposed young men living in a malaria area in the Limpopo Province, South Africa.

BACKGROUND: There is mounting evidence that deteriorated semen quality may be associated with increased serum concentration of 1,1,1-trichloro-2,2-bis(chlorodiphenyl)ethane (DDT) and its metabolites. The problem is exacerbated in situations where DDT is the only resource available to control malaria mosquitoes and DDT metabolite plasma concentration can reach 1000-fold the level found in other populations. There are limited and contradictory epidemiological data on whether DDT/dichlorodiphenyl-dichloroethylene (DDE) can also damage sperm DNA. Therefore, there is a need to investigate the possible adverse effects on human sperm genetic integrity in a sufficiently large study population with adequate exposure contrasts, especially in the high exposure range. METHODS: We conducted a cross-sectional study, recruiting 209 young males from three communities in an endemic malaria area where DDT is sprayed annually. Blood plasma p,p'-DDT and its metabolite p,p'-DDE levels were measured and expressed as lipid adjusted p,p'-DDT and p,p'-DDE values. The sperm chromatin structure assay and Aniline Blue test were used to assess sperm DNA/chromatin integrity. RESULTS: The lipid adjusted p,p'-DDT mean (+/-SD) and median concentrations were 109.2 (+/-106.6) and 83.9 microg/g, respectively; and the lipid adjusted p,p'-DDE mean (+/-SD) and median concentrations were 246.2 (+/-218.5) and 177.8 microg/g, respectively. The results point to a weak association between DDT/DDE plasma concentration and the incidence of sperm with chromatin defects. CONCLUSIONS: The results suggest that non-occupational environmental DDT exposure may have a negative impact on sperm chromatin integrity in young South African males.

Differential effects of infralimbic cortical lesions on temperature and locomotor activity responses to feeding in rats.

The time of food availability induces important behavioral and metabolic adaptations. Animals subjected to feeding restricted to a few daytime hours show increased locomotor activity and body temperature in anticipation of mealtime. In addition, animals under ad libitum feeding show a marked postprandial raise in body temperature and in thermogenesis. The areas of the brain commanding these responses to food are partially known. We investigated in the rat the role of the infralimbic area, located in the medial prefrontal cortex, and considered a visceral-autonomic motor area, in the responses to ad libitum or restricted feeding schedule. We performed infralimbic cortex excitotoxic lesions using injections of ibotenic acid, and measured body temperature and locomotor activity by telemetry in rats under ad libitum and restricted feeding conditions. We found that bilateral infralimbic area lesions prevented both the anticipatory and the postprandial increases in core temperature, decreased mean temperature by nearly 0.3 degrees C during both light/dark phases, and increased daily temperature variability. In contrast, the lesion caused a rapid induction of the anticipatory locomotor activity. These results show that behavioral and metabolic responses to the time of food availability are commanded separately and that the infralimbic area is a key structure to adjust the body temperature to an upcoming meal.

Rat visceral yolk sac cells: viability and expression of cell markers during maternal diabetes.

The function of the visceral yolk sac (VYS) is critical for embryo organogenesis until final fetal development in rats, and can be affected by conditions such as diabetes. In view of the importance of diabetes during pregnancy for maternal and neonatal health, the objective of this study was to assess fetal weight, VYS cell markers, and viability in female Wistar rats (200-250 g) with induced diabetes (alloxan, 37 mg/kg) on the 8th gestational day (gd 8). At gd 15, rats from control (n=5) and diabetic (n=5) groups were anesthetized and laparotomized to remove the uterine horns for weighing of fetuses and collecting the VYS. Flow cytometry was used for characterizing VYS cells, and for determining mitochondrial activity, cell proliferation, DNA ploidy, cell cycle phases, and caspase-3 activity. Fetal weight was reduced in the diabetic group. Expression of the cell markers CD34, VEGFR1, CD115, CD117, CD14, CCR2, CD90, CD44, STRO-1, OCT3/4, and Nanog was detected in VYS cells in both groups. In the diabetic group, significantly decreased expression of CD34 (P<0.05), CCR2 (P<0.001), and OCT3/4 (P<0.01), and significantly increased expression of CD90 (P<0.05), CD117 (P<0.01), and CD14 (P<0.05) were observed. VYS cells with inactive mitochondria, activated caspase-3, and low proliferation were present in the rats with diabetes. Severe hyperglycemia caused by maternal diabetes had negative effects on pregnancy, VYS cell viability, and the expression of cell markers.

Determinants of bone and blood lead levels among teenagers living in urban areas with high lead exposure.

Although lead has been extensively studied in children, its sources and effects remain unclear in adolescents. This study examined the relation of blood and tibia bone lead levels to lead determinants. One hundred adolescents living in Mexico City and surrounding suburbs were studied. Blood lead was measured by atomic absorption spectroscopy, and tibia lead was measured by a K X-ray Fluorescence (KXRF) instrument. Blood lead ranged from 1.8 to 29.2 microgram/dl, with a mean of 7.4 microgram/dl. Bone lead ranged from <1 to 44.82 microgram Pb/g bone mineral, with a mean of 4.8 microgram Pb/g. Predictors of bone lead included higher traffic density near the home, mother's smoking history, and time spent outdoors. Predictors of log-transformed blood lead included bone lead levels, male sex, use of lead-glazed ceramics, and living in Mexico City. Bone lead remained a significant predictor of blood lead after adjusting for covariates in a final multivariate regression model. In our final model, a rise in bone lead from the middle of the lowest quintile to the middle of the highest quintile (a difference of 21.6 microgram Pb/g) was associated with an increase in blood lead of 1.2 microgram/dl. Our data suggest that in addition to current sources of environmental lead exposure, bone lead accumulated over time constitutes a moderate source of circulating lead during adolescence and may account for some of the adverse health effects documented in recent studies.

Blood lead levels in pregnant women of high and low socioeconomic status in Mexico City.

This study examined the determinants of blood lead (BPb) in 513 pregnant women in Mexico City: 311 from public hospital prenatal clinics, representing primarily women of low socioeconomic status (SES), and 202 from private hospitals, primarily women of high SES. Overall, BPb levels ranged from 1.38 to 29 micrograms/dl, with geometric means of 6.7 and 11.12 micrograms/dl for women from private and public hospitals, respectively. The crude geometric means difference obtained by t-test was 4.42 (p < 0.001). BPb was measured from January 1994 to August 1995 and showed higher levels during fall and winter and lower levels during spring and summer. The main BPb determinants were the use of lead-glazed ceramics in women from public hospitals and season of the year in women from private hospitals. Consumption of tortillas (corn bread rich in calcium) decreased BPb levels in the lower SES group, but the relationship was not statistically significant (p > 0.05). Consumption of milk products significantly (p < 0.05) reduced BPb levels in the higher SES group. In 112 women whose diets were deficient in calcium, taking calcium supplements lowered their blood lead levels about 7 micrograms/dl. A predictive model fitted to these data, using the strongest predictors plus gestational age, showed a difference of 14 micrograms/dl between the best and worst scenarios in women from public hospitals. Avoiding use of lead-glazed ceramics, consuming diets rich in calcium, and, if needed, taking calcium supplements, would be expected to result in substantial lowering of BPb, especially in pregnant women of low socioeconomic status.

The cytotoxic and embryotoxic effects of kaurenoic acid, a diterpene isolated from Copaifera langsdorffii oleo-resin.

In this work, we studied the effects of kaurenoic acid, a diterpene isolated from the oleo-resin of Copaifera langsdorffii in developing sea urchin (Lytechinus variegatus) embryos, on tumor cell growth in microculture tetrazolium (MTT) test and on mouse and human erythrocytes in hemolysis assay. Continuous exposure of embryos to kaurenoic acid starting immediately after fertilization inhibited the first cleavage (IC(50): 84.2 microM) and progressively induced embryo destruction (IC(50): 44.7 microM and < 10 microM for blastulae and larvae stages, respectively). In MTT assay, kaurenoic acid at a concentration of 78 microM produced growth inhibition of CEM leukemic cells by 95%, MCF-7 breast and HCT-8 colon cancer cells by 45% each. Further, kaurenoic acid induced a dose-dependent hemolysis of mouse and human erythrocytes with an EC(50) of 74.0 and 56.4 microM, respectively. The destruction of sea urchin embryos, the inhibition of tumor cell growth and the hemolysis of mouse and human erythrocytes indicate the potential cytotoxicity of kaurenoic acid.

An analysis of various environmental and specific sensory stimuli on the seizure activity of the Mongolian gerbil.

Mongolian gerbils were subjected to different environmental and specific sensory stimuli to determine the ability of these stimuli to provoke seizures. None of the specific sensory stimuli, somatosensory, olfactory, auditory or visual, were effective in inducing convulsions. This finding does not implicate dysfunctions of the specific sensory pathways in seizure genesis in gerbils. In contrast, several novel environmental stimuli that exposed the animals to a difficult exploratory task (i.e., Y-maze, disk rack, etc.) could trigger seizures, and this suggests that the pathophysiology of epileptiform events in gerbils may have a unique association with exploratory behavior. However, the frequency, latency and severity of the seizures showed no correlation with each other, indicating that these parameters are probably determined by independent factors. Taken together with previous studies on the electrophysiology of the dentate gyrus during exposure to novel experiences, and the anatomical abnormalities found in the hippocampus of the seizure-sensitive gerbil, these behavioral data provide further support for a significant role of the hippocampus in the pathophysiology of seizures in this model of genetic epilepsy.

The social meanings of nervios: a case study of a Central American woman.

This paper analyzes nervios among Central American refugees living in the United States. Nervios is analyzed as personal descriptions of distress, statements about family relations, and commentaries on the broader social forces affecting people's lives. A description of the clinical presentations of 28 Salvadorans who suffer from nervios and an indepth analysis of an extended interview with a nervios sufferer are presented to examine the multiple meanings of nervios. Nervios is identified as a powerful idiom of distress used by Latinos to express concerns about physical symptoms, emotional states, and changes both in the family and in the broader society.

Cathodic adsorptive stripping voltammetry of nickel complexed with hydroxynaphthol blue at a static mercury drop electrode.

A new method is described for the determination of Ni based on the cathodic adsorptive stripping of Ni(II) complexed with hydroxynaphthol blue (HNB) at a static mercury drop electrode. Optimal conditions were found to be: accumulation potential -0.50 V (vs. Ag/AgCl); final potential -1.10 V; accumulation time 50 sec; scan rate 200 mV/sec; linear scan mode; filter 0.1 sec; supporting electrolyte acetic acid/acetate (0.25M, pH = 6.0) and concentration of HNB 3.3 x 10(-5)M. The response of the system was found to be linear in a range of Ni concentrations from 25 ppb to the detection limit. The detection limit was found to be 1.7 nM (0.10 ppb) with 2 mins of accumulation time. The effect of various potential interferences (including a variety of cations, anions and organic surfactants) were also studied. With the exception of Co, at less than equimolar concentrations no significant interferences were observed. Al was found to interfere at high concentrations with respect to Ni, but Al concentrations up to 1000 ppb may be masked by sodium citrate or sodium fluoride. The utility of the method is demonstrated by the recovery of Ni in a doped sample of commercial mineral water.

Adsorptive stripping voltammetric behaviour of copper complexes of some heterocyclic azo compounds.

Controlled adsorptive accumulation of copper complexed with TAN, TAC, TAR and TAM (heterocyclic azo-compounds) on a static mercury drop electrode provides the basis for the direct stripping measurement of this element in the nanomolar concentration level. The ligand TAN exhibited great sensitivity and better separation of the peak current of the ligand in relation to the complex. The reduction current of adsorbed complex ions of copper is measured by linear scan cathodic stripping voltammetry, preceded by a period of accumulation of a few minutes. The peak potential is at approximately -0.37 V vs. Ag/AgCl. Optimal experimental parameters were found to be a TAN concentration of 1 x 10(-5)M, an accumulation potential of -0.22 V, and a solution pH of 3.7 (acetate buffer). The detection limit is 0.8nM after a 5-min accumulation with a stirred solution, and the response is linear up to 50 mug/l. Many common cations and anions do not interfere in the determination of copper. The interference of titanium is eliminated by addition of fluoride ion. Results are reported for a fresh water sample.

Diftalone: a new non-steroidal anti-inflammatory agent: comparative study with phenylbutazone in the treatment of rheumatoid arthritis.

A double-blind study was carried out to compare the effectiveness and tolerability of diftalone and phenylbutazone in thirty patients with classical or definite rheumatoid arthritis, randomly distributed between the two treatment groups. Both drugs were administered according to a progressively decreasing daily dosage schedule: 1,000 mg during the 1st week; 750 mg the 2nd week and 500 mg from the 3rd week on for diftalone; 400 mg, 300 mg, and 200 mg daily for the 1st, 2nd and from the 3rd week on respectively for phenylbutazone. The study lasted twelve weeks. The clinical controls and laboratory tests were performed weekly up to the 8th week, while the final evaluation was made at the end of the 3rd month. Twelve patients in the group receiving diftalone and fourteen in the phenylbutazone group completed the trial. Clinical improvement was observed in both groups. Effectiveness was somewhat more evident in the diftalone group. Tolerability was acceptable for both drugs, althoug the diftalone patients showed less frequent and intense side-effects than those treated with phyenylbutazone. No significant differences were found as regards the laboratory parameters, except a significant fall of the E.S.R. (less than 0-05) in the diftalone group. Diftalone seems to be an effective and safe anti-inflammatory agent in the treatment of rheumatoid arthritis.

Using Geostatistical Analysis to Evaluate the Presence of Rotylenchulus reniformis in Cotton Crops in Brazil: Economic Implications.

In recent years, the productivity of cotton in Brazil has been progressively decreasing, often the result of the reniform nematode Rotylenchulus reniformis. This species can reduce crop productivity by up to 40%. Nematodes can be controlled by nematicides but, because of expense and toxicity, application of nematicides to large crop areas may be undesirable. In this work, a methodology using geostatistics for quantifying the risk of nematicide application to small crop areas is proposed. This risk, in economic terms, can be compared to nematicide cost to develop an optimal strategy for Precision Farming. Soil (300 cm(3)) was sampled in a regular network from a R. reniformis-infested area that was a cotton monoculture for 20 years. The number of nematodes in each sample was counted. The nematode number per volume of soil was characterized using geostatistics, and 100 conditional simulations were conducted. Based on the simulations, risk maps were plotted showing the areas where nematicide should be applied in a Precision Farming context. The methodology developed can be applied to farming in countries that are highly dependent on agriculture, with useful economic implications.

Descripción demográfica, clínica y anatomopatológica de las microcirugías de laringe: estudio retrospectivo en el Hospital Británico de Buenos Aires / Demographic, clinical, and anatomopathological description of larynx microsurgeries: Retrospective study at Hospital Británico de Buenos Aires / Descrição demográfica, clínica e anatomopatológica das microcirurgias de laringe: estudo retrospectivo no Hospital Britânico de Buenos Aires

Objetivo: la microcirugía laríngea es un procedimiento terapéutico en lesiones benignas de laringe, diagnóstico en pacientes con disfonías de evolución variable y en casos de sospecha de malignidad. El objetivo de este estudio es describir las características de los pacientes intervenidos por microcirugía laríngea y las lesiones observadas en un servicio de otorrinolaringología en Argentina. Metodología: estudio retrospectivo. Se realizó la revisión de protocolos quirúrgicos, historias clínicas, videoestroboscopias computarizadas y documentos de anatomía patológica. Análisis univariado descriptivo con utilización de la t de Student o la Chi- cuadrado, según las características de las variables (p <0.005 para significancia estadística). Resultados: el sexo masculino fue el más intervenido, con una edad media de 51.2 ± 6.6 años. El antecedente de tabaquismo fue el más frecuente. Las principales lesiones macroscópicas fueron premalignas y malignas, pólipos y quistes. En la anatomía patológica se encontraron pólipos, carcinomas y quistes. En ambos sexos la lesión más frecuente fue el pólipo (33% vs. 45%, p =0.03). En pacientes con antecedente de tabaquismo la lesión más común fue pólipo, en ambos géneros, en menores de 60 años (46% vs. 30%, p =0.02), mientras en mayores de 60 años fue el carcinoma (33% vs. 15%, p <0.001). Conclusiones: en población masculina en sexta década de la vida se encontró principalmente presencia de pólipos, quistes y carcinomas. En pacientes de este género, con antecedente de tabaquismo, se describe mayor presencia de carcinomas.

Objective: Laryngeal microsurgery is a procedure indicated in benign laryngeal lesions; it is also a diagnostic tool in patients with dysphonia or in cases where malignancy is suspected. Methodology: Retrospective study in which clinical records, surgical protocols, videoestroboscopies, and pathology documents of patients under laryngeal microsurgery between 2011 and 2016 were reviewed. Univariate analysis was performed using Chi squared test (p <0.05). Results: Mean age was 51.2 ± 6.6 years, males were the most frequently intervened. Smoking was the most common comorbidity. The main macroscopic lesions observed were premalignant and malignant, polyps and cysts; in the pathology, polyps, carcinomas, and cysts were found. Polyps were the most frequent lesions found in both genders (33% vs 45%, p = 0.03). In patients with a smoking comorbidity, polyps were the most common lesion in both women and men (46% vs. 30%, p = 0.02). A greater presence of carcinomas was described in males over 60 with a history of smoking (33% vs 15%, p = 0.0001). Conclusions: Polyps, cysts, and carcinomas were mainly found in males over 60. A greater presence of carcinomas was described in male patients with a history of smoking.

Objetivo: a microcirurgia laríngea é um procedimento terapêutico em lesões benignas de laringe, diagnóstico em pacientes com disfonias de evolução variável e em casos de suspeita de malignidade. O objetivo deste estudo é descrever as características dos pacientes intervindos por microcirurgia laríngea e as lesões observadas num serviço de otorrinolaringologia na Argentina. Metodologia: estudo retrospectivo. Se realizou a revisão de protocolos cirúrgicos, histórias clínicas, videoestroboscopias computorizadas e documentos de anatomia patológica. Análise univariado descritivo com utilização da t de Student ou a Chi- quadrado, segundo as características das variáveis (p <0.005 para significância estatística). Resultados: o sexo masculino foi o mais intervindo, com uma idade média de 51.2 ± 6.6 anos. O antecedente de tabaquismo foi o mais frequente. As principais lesões macroscópicas foram pré-malignas e malignas, pólipos e quistos. Na anatomia patológica se encontraram pólipos, carcinomas e quistos. Em ambos sexos a lesão mais frequente foi o pólipo (33% vs. 45%, p =0.03). Em pacientes com antecedente de tabaquismo a lesão mais comum foi pólipo, em ambos gêneros, em menores de 60 anos (46% vs. 30%, p =0.02), enquanto em maiores de 60 anos foi o carcinoma (33% vs. 15%, p <0.001). Conclusões: na população masculina na sexta década da vida se encontrou principalmente presença de pólipos, quistos e carcinomas. Em pacientes deste gênero, com antecedente de tabaquismo, se descreve maior presença de carcinomas.

Grazing criteria for perennial peanut (Arachis pintoi cv. Amarillo) consumed by sheep in rotational stocking / Critérios de pastejo para amendoim forrageiro (Arachis pintoi cv. Amarillo) consumido por ovelhas em sistema rotacionado

The objective of work was to study the productive profile of perennial peanut in a rotational stocking environment under different criteria. The treatments corresponded to pre-grazing height of 14 and 18cm or 95% of light interception (LI) distributed in a completely randomized design. The studied variables were forage mass, percentage of structural components, forage mass and the structural components in the lower and upper canopy strata. The entrance criterion of 18cm in height, despite having higher forage mass, presented lower percentage of leaves and higher percentage of stems and forage losses. The criteria of 14cm and 95% light interception presented similar production between them and the highest rate of forage accumulation. In all criteria, in the upper strata of pasture a higher percentage of leaves were found. The criteria of 95% LI and 14cm in height presented the best productive performances. The entry criterion of 18cm presented a higher mass of pre-grazing forage with lower percentage of dead material, but with higher forage losses, resulting from senescent leaves. Due to changes in the structural components, as grazing cycles increase, the interception of 95% of the incident light by the perennial peanut occurs at lower heights.(AU)

O objetivo do presente trabalho foi estudar o perfil produtivo do amendoim forrageiro em um ambiente rotacionado, sob diferentes critérios. Os tratamentos corresponderam à altura de pré-pastejo de 14 e 18cm ou 95% de intercepção de luz (LI), distribuídos em delineamento inteiramente ao acaso. As variáveis estudadas foram massa forrageira, porcentagem de componentes estruturais, densidade da massa forrageira e densidade dos componentes estruturais nos estratos do dossel inferior e superior. O critério de entrada de 18cm de altura, apesar de ter maior massa forrageira, apresentou menor porcentagem de folhas e maior porcentagem de hastes e perdas de forragem. Os critérios de interceptação de luz de 14cm e 95% apresentaram produção similar entre eles e a maior taxa de acumulação de forragem. Em todos os critérios, no estrato superior de pastagem, foi encontrada maior porcentagem de folhas. Os critérios de 95% LI e 14cm de altura apresentaram os melhores desempenhos produtivos. O critério de entrada de 18cm apresentou maior massa de forragem pré-pastagem com menor porcentagem de material morto, mas com maiores perdas de forragem, resultantes de folhas senescentes. Devido às mudanças nos componentes estruturais, à medida que os ciclos de pastagem aumentam, a intercepção de 95% da luz incidente pelo amendoim forrageiro ocorre em alturas mais baixas.(AU)

Short term inhalation toxicity of a liquid aerosol of glutaraldehyde-coated CdS/Cd(OH)2 core shell quantum dots in rats.

Quantum dots exhibit extraordinary optical and mechanical properties, and the number of their applications is increasing. In order to investigate a possible effect of coating on the inhalation toxicity of previously tested non-coated CdS/Cd(OH)2 quantum dots and translocation of these very small particles from the lungs, rats were exposed to coated quantum dots or CdCl2 aerosol (since Cd(2+) was present as impurity), 6h/d for 5 consecutive days. Cd content was determined in organs and excreta after the end of exposure and three weeks thereafter. Toxicity was determined by examination of broncho-alveolar lavage fluid and microscopic evaluation of the entire respiratory tract. There was no evidence for translocation of particles from the respiratory tract. Evidence of a minimal inflammatory process was observed by examination of broncho-alveolar lavage fluid. Microscopically, minimal to mild epithelial alteration was seen in the larynx. The effects observed with coated quantum dots, non-coated quantum dots and CdCl2 were comparable, indicating that quantum dots elicited no significant effects beyond the toxicity of the Cd(2+) ion itself. Compared to other compounds with larger particle size tested at similarly low concentrations, quantum dots caused much less pronounced toxicological effects. Therefore, the present data show that small particle sizes with corresponding high surfaces are not the only factor triggering the toxic response or translocation.

Short term inhalation toxicity of a liquid aerosol of CdS/Cd(OH)2 core shell quantum dots in male Wistar rats.

Colloidal quantum dots (QD) show great promise as fluorescent markers. The QD used in this study were obtained in aqueous medium rather than the widely used colloidal QD. Both methodologies used for the production of QD are associated with the presence of heavy metals such as cadmium (Cd). Here we investigate the short-term inhalation toxicity of water-soluble core-shell CdS/Cd(OH)2 QD. Male Wistar rats were head-nose exposed for 6 h/day on 5 days at the technically maximum concentration (0.52 mg Cd/m³). Histological examination was performed directly after the last exposure. Additional rats were used for Cd organ burden determinations. Clinical parameters in blood, bronchoalveolar lavage fluid and lung tissue were determined 3 days after the last exposure. To analyze the reversibility or progression of effects, the examinations were performed again after a recovery period of 3 weeks. The results of the study indicate that CdS/Cd(OH)2 QD caused local neutrophil inflammation in the lungs that partially regressed after the 3-week recovery period. There was no evidence that QD were translocated to the central nervous system nor that a systemic acute phase response occurred.

Studying taxis in real time using optical tweezers: applications for Leishmania amazonensis parasites.

Beads trapped by an optical tweezers can be used as a force transducer for measuring forces of the same order of magnitude as typical forces induced by flagellar motion. We used an optical tweezers to study chemotaxis by observing the force response of a flagellated microorganism when placed in a gradient of attractive chemical substances. This report shows such observations for Leishmania amazonensis, responsible for leishmaniasis, a serious disease. We quantified the movement of this protozoan for different gradients of glucose. We were able to observe both the strength and the directionality of the force. The characterization of the chemotaxis of these parasites can help to understand the mechanics of infection and improve the treatments employed for this disease. This methodology can be used to quantitatively study the taxis of any kind of flagellated microorganisms under concentration gradients of different chemical substances, or even other types of variable gradients such as temperature and pressure.