Effects of NADH and H(2)O(2) on chromate-induced human erythrocytes hemoglobin oxidation and peroxidation

The effects of NADH and H(2)O(2) on chromate-induced human erythrocyte hemoglobin oxidation and peroxidation were studied. It was observed that NADH decreases the levels of chromate-induced human erythrocyte hemoglobin oxidation and peroxidation. H(2)O(2) decreases the levels of chromate-induced hemoglobin oxidation, but increases the levels of chromate-induced peroxidation. The ability of H(2)O(2) to decrease the levels of chromate-induced hemoglobin oxidation is higher than that observed for NADH. Furthermore, H(2)O(2) increases the inhibitory effect of NADH on chromate-induced hemoglobin oxidation, but decreases the NADH effect on chromate-induced peroxidation. The meaning of these results is discussed in terms of involvement of reactive chromium(V) species and reactive oxygen species in the mechanism by which chromate induces its effects in human erythrocytes.

Post-transplant lymphoproliferative disorders (PTLD) after renal transplantation: management and evolution of seven cases among 1002 renal transplants in São Paulo, Brazil

We reported seven cases (0.7%) of PTLD among 1002 renal transplants performed at Renal Transplant Service from Hospital São Paulo-Universidade Federal de São Paulo/Escola Paulista de Medicina, São Paulo, Brazil, between 1976 and 1997. There were three male and four female patients with median age of 37 year-old. According to Ann Arbor staging system there were four localized extra-nodal intermediate-grade NHL, one disseminated low-grade NHL and two polyclonal lymphoid hyperplasia. Four patients received cadaveric, two received related and one received unrelated renal transplant. PTLD occurred after a median latency period of 36 months (ranging from 5 to 84 months). In situ hybridization for EBER1 was performed in five patients and molecular evidence of EBV was found in 3 cases (two DLCL and one lymphoplasmocytoid lymphoma). All patients were treated with immunosuppression withdrawal, four patients received anthracyclin-based chemotherapy for control of localized or systemic clonal disease and three were treated with resection of primary PTLD. Four of seven patients (57%) are in complete remission 11, 20, 25 and 79 months after PTLD onset. One patient lost follow-up and two patients died due to lymphoma relapse, respectively 4 and 10 months after completion of treatment. In conclusion, our experience with this small group of patients showed that: 1) immunosuppression withdrawal is not necessarily associated with loss of renal transplant and can be used as the only treatment for polyclonal PTLD; 2) chemotherapy can simultaneously lead to clonal PTLD remission and periodic immunosuppression, avoiding graft rejection after immunosuppression withdrawal.

Controlling for stimulus dominance effects in the Fused Dichotic Words Test when predicting speech lateralization in children

A log-linear analysis (Grimshaw et al., 1994) of Fused Dichotic Words Test data was examined in a sample of 28 children with epilepsy who had undergone the intracarotid amobarbital procedure to determine the nature of speech representation. The analysis yields a measure of ear dominance (lambda*) that controls for stimulus dominance confounds. Most patients with unilateral speech obtained statistically significant ear advantages, whereas most with bilateral speech displayed no significant ear advantage. Despite controlling for stimulus dominance confounds, some of the scores from patients with left-hemisphere speech overlapped with those from patients with bilateral speech representation.

Divided attention and memory: evidence of substantial interference effects at retrieval and encoding

In 5 divided attention (DA) experiments, students (24 in each experiment) performed visual distracting tasks (e.g., recognition of words, word and digit monitoring) while either simultaneously encoding an auditory word list or engaging in oral free recall of the target word list. DA during retrieval, using either of the word-based distracting tasks, produced relatively larger interference effects than the digit-monitoring task. DA during encoding produced uniformly large interference effects, regardless of the type of distracting task. Results suggest that when attention is divided at retrieval, interference is created only when the memory and concurrent task compete for access to word-specific representational systems; no such specificity is necessary to create interference at encoding. During encoding, memory and concurrent tasks compete primarily for general resources, whereas during retrieval, they compete primarily for representational systems.

Chromate-induced human erythrocytes haemoglobin oxidation and peroxidation: influence of vitamin E, vitamin C, salicylate, deferoxamine, and N-ethylmaleimide

In order to attenuate or to prevent chromate-induced human erythrocytes injury, the influence of vitamin E, vitamin C, salicylate, deferoxamine, and N-ethylmaleimide on chromate-induced human erythrocytes haemoglobin oxidation and peroxidation were investigated. It was observed that pretreatment of human erythrocytes with vitamin E (20 microM), vitamin C (1 mM), salicylate (3 mM), and deferoxamine (4 mM) significantly increased (P=0.0001) chromate-induced human erythrocytes haemoglobin oxidation in a time dependent manner, while it was significantly decreased (P=0.0001) by pretreatment with N-ethylmaleimide (1 mM). In contrast, pretreatment of human erythrocytes with deferoxamine (4 mM) immediately inhibited (P=0.0001) chromate-induced human erythrocytes peroxidation, while it was significantly increased (P=0.0001) by pretreatment with N-ethylmaleimide (1 mM) during the first 4 h of cells exposition to chromate. For time periods superior to 6 h pretreatment with N-ethylmaleimide (1 mM) significantly decreased (P=0.0001) chromate-induced human erythrocytes peroxidation. It was concluded that care must be taken as these drugs are used to prevent against toxicity induced by chromium(VI) compounds.

Brachytherapy using gold-198 foils in treatment of mouth tumors: case report

The authors presents a clinical case treated with brachytherapy performed with special mold of gold-198 disc, with the purpose of evaluating the distribution of radiation dose, the viability of manufacturing the radioactivity prosthesis and its operational cost. In despite of being only one case, we can conclude that the prosthesis with gold-198 foils can be manufactured in acrylic with thickness thinner than those ones with cylinder of cesium-137, resulting lower operational costs, besides permitting better distribution of radiation dose on the lesion.

Influence of apolipoprotein E genotype on blood redox status of Alzheimer's disease patients

The blood redox status of probable Alzheimer's Disease (AD) patients and control subjects with distinct Apo E genotypes was investigated. It was assessed by measuring the levels of hydroperoxides (MDA) in plasma and erythrocytes, the levels of the antioxidant defense system (enzymatic and non-enzymatic) in plasma, erythrocytes, platelets and leukocytes, the activities of catechol-O-methyltransferase (COMT) in erythrocytes and monoamine oxidase-B (MAO-B) in platelets and also the activity of the mitochondrial respiratory chain in leukocytes. No significant differences were found between the Apo E genotype and MDA, uric acid, vitamin E and reduced-glutathione (GSH) levels in plasma; MDA, vitamin E, GSH, superoxide-dismutase (SOD), glutathione-peroxidase (GSH-Px) and COMT levels in erythrocytes; vitamin E levels in the platelets of AD patients and control subjects. However, the uric acid levels in plasma and the COMT levels in erythrocytes of AD patients and control subjects with the epsilon4 allele were significantly lower than those observed in control subjects without the epsilon4 allele. Moreover, the duraquinol oxidation level in leukocytes of AD patients with the epsilon4 allele was significantly higher than that in AD patients without the epsilon4 allele and control subjects with and without the epsilon4 allele. The meaning of these results is discussed in terms of involvement of oxidative stress in the etiopathogenesis of AD.

Effects of apolipoprotein E genotype on blood lipid composition and membrane platelet fluidity in Alzheimer's disease

The blood lipid composition (plasma, platelets and leukocytes), platelet membrane fluidity, apolipoproteins A and B in the plasma of AD patients and control subjects with distinct Apo E genotypes were investigated. No significant differences were found between the Apo E genotype and the cholesterol, phospholipids, triglycerides and Apo B levels in the plasma; cholesterol and phospholipids levels in platelet and leukocyte membranes; and platelet membrane fluidity of AD and control groups. However, the phospholipid levels in the leukocyte membranes of the control subgroup with the genotypes epsilon3/epsilon3 and epsilon3/epsilon4 and the AD subgroups with the genotypes epsilon2/epsilon3 and epsilon3/epsilon3, epsilon3/epsilon4 and epsilon4/epsilon4 were significantly lower than those observed in the control subgroup with the genotype epsilon2/epsilon3. Moreover, the cholesterol and phospholipid levels in the platelet membranes of the AD subgroup with the epsilon2 allele were significantly higher than those in the AD subgroup without the epsilon2 allele and the control subgroups with and without the epsilon2 allele. A strong correlation was found between cholesterol and phospholipids levels in the platelet membranes of the AD and control subgroups without the epsilon2 allele, but the residual cholesterol level in the platelet membranes of the AD subgroup was twice that observed in the control subgroup. Furthermore, the Apo A levels in the plasma of the AD subgroup with the epsilon3 allele were significantly lower than those observed in the AD subgroup without the epsilon3 allele and the control subgroup with the epsilon3 allele. The results are discussed in terms of involvement of lipid metabolism in the etiopathogenesis of AD.

Human erythrocytes are protected against chromate-induced peroxidation

In previous studies performed in this laboratory it was realized that in a broad concentration range (0.5-8 mM) dichromate does not induced red blood cell (RBC) peroxidation. To investigate the reasons behind RBC protection against chromate-induced peroxidation, the effects of 8 mM dichromate on white ghost and RBC peroxidation, RBC antioxidant system and hemoglobin status, as well as RBC osmotic fragility and morphology, were studied in more detail. It was observed that the peroxidation level induced by dichromate on RBCs is practically negligible when compared with the peroxidation induced in white ghosts. Furthermore, the osmotic fragility of RBCs exposed to dichromate is not altered, but the cells undergo echinocytic transformation, probably due to chromate-induced structural RBC membrane modifications. The activities of catalase, gluthatione peroxidase, and superoxide dismutase of RBCs exposed to dichromate were similar to those observed in controls, but the gluthatione reductase and GSH levels were significantly reduced (P<0. 05). Concomitantly, GSSG and methemoglobin levels increased and NADH-methemoglobin reductase activity decreased. These results indicate that chromate does not induce RBC peroxidation, but does promote echinocytic shape transformation, oxidation of hemoglobin and GSH, and inhibition of gluthatione reductase and methemoglobin reductase. The enzymatic antioxidant defense system and hemoglobin oxidation are probably involved in the mechanism of RBC proctection against chromate-induced peroxidation, as is discussed.

Apolipoprotein E genotype has no effect on the free intracellular Ca2+ concentration of platelets from Alzheimer's disease patients

The free intracellular Ca2+ concentration [Ca2+]i of platelets was investigated in Alzheimer's disease (AD) patients and age-matched control subjects with distinct Apo E genotypes. No significant differences were found between the Apo E genotype and the [Ca2+]i levels of platelets (basal and alpha-thrombin stimulated) from AD patients and age-matched control subjects, suggesting that [Ca2+]i homeostasis of platelets from AD patients is independent of the Apo E genotype. The results are discussed in terms of involvement of Apo E and [Ca2+]i changes in the etiopathogenesis of AD.

[Results of activities encouraging community participation in dengue control in an outlying neighborhood of São José do Rio Preto, São Paulo, and the relationship between the population's knowledge and habits]

This study evaluates the results of an educational campaign developed in an outlying neighborhood of São José do Rio Preto, São Paulo, and the relationship between the population's knowledge and habits. Prior to and after the educational activities, samples were taken to measure level of knowledge concerning dengue and its vectors, breeding sites, and control measures. Potential breeding sites were also counted. Knowledge of the disease and its vectors and breeding sites increased, but the same was not true for control measures focusing on water recipients serving as potential breeding sites. There was no change in the number of breeding sites between the first and second stages of the research. Thus, despite increased knowledge, the local population's habits did not changes. These findings are worrisome, since the main goal of the educational campaign, i.e., the change of habits concerning breeding sites for dengue vectors, has not been achieved.

Detection and quantification of microorganisms in a heterogeneous foodstuff by image analysis

A relatively inexpensive image analysis system has been developed to semi-automate the detection and quantification of microbial growth in sections of food. A system based on an IBM PC compatible, with a frame store card, was programmed to scan Gram-stained sections using a motorized stage. Each field of view was thresholded after subtraction of a background image and the area between two thresholds measured. In the food studied it was found that, by using a size limit, it was possible to reduce the number of fields that needed to be examined by a microscopist to approximately 3% of those scanned. Visual examination was still required to distinguish bacterial cells from other stained objects which occasionally occur.

The role of monaural frequency selectivity in binaural analysis

The relation between the monaural critical band and binaural analysis was examined using an NoSm MLD paradigm, in order to resolve ambiguities about the width of the masking spectrum important for binaural detection. A 500-Hz pure-tone signal was presented with a 600-Hz-wide band of masking noise to the signal ear. Bands of noise ranging in width from 25 to 600 Hz, or noise notches (imposed on a 600-Hz-wide band centered on the signal frequency) ranging in width from 0 to 600 Hz were presented to the nonsignal ear. All noise bands and notches were centered on 500 Hz, the frequency of the signal. The effects of varying bandwidth were radically different from those of varying notchwidth: the MLD changed from zero to approximately 8 dB over a bandwidth range of 400 Hz; for notchwidths, however, the MLD changed 8 dB over a range of only 50 Hz. The results support an interpretation that the fine frequency selectivity of monaural analysis is preserved in peripheral binaural interaction, but that a relatively wide frequency range of critical bands is scanned at a later stage of binaural processing. It was suggested that the wide spectral range of binaural analysis may provide a background against which binaural differences due to the signal are detected.

Detection in noise by spectro-temporal pattern analysis

Detectability of a 400-ms, 1000-Hz pure-tone signal was examined in bandlimited noise where different spectral regions were given similar waveform envelope characteristics. As expected, in random noise the threshold increased as the noise bandwidth was increased up to a critical bandwidth, but remained constant for further increases in bandwidth. In the noise with envelope coherence however, threshold decreased when the noise bandwidth was made wider than the critical bandwidth. The improvement in detectability was attributed to a process by which energy outside the critical band is used to help differentiate signal from masking noise, provided that the waveform envelope characteristics of the noise inside and outside the critical band are similar. With flanking coherent noise bands either lower or higher in frequency than a noise band centered on the signal, it was next determined that the frequency relation and remoteness of the coherent noise did not particularly influence the magnitude of the unmasking effect. An interpretation in terms of nonsimultaneous masking was reconciled with some aspects of the data, and with an interpretation in terms of across-frequency temporal pattern analysis. This paradigm, in which detection is based upon across-frequency temporal envelope coherence, was termed "comodulation masking release." Comodulation offers a controlled way to investigate some of the mechanisms which permit signals to be detected at adverse signal-to-noise ratios.