Construction of effective disposable biosensors for point of care testing of nitrite

In this paper we aim to demonstrate, as a proof-of-concept, the feasibility of the mass production of effective point of care tests for nitrite quantification in environmental, food and clinical samples. Following our previous work on the development of third generation electrochemical biosensors based on the ammonia forming nitrite reductase (ccNiR), herein we reduced the size of the electrodes' system to a miniaturized format, solved the problem of oxygen interference and performed simple quantification assays in real samples. In particular, carbon paste screen printed electrodes (SPE) were coated with a ccNiR/carbon ink composite homogenized in organic solvents and cured at low temperatures. The biocompatibility of these chemical and thermal treatments was evaluated by cyclic voltammetry showing that the catalytic performance was higher with the combination acetone and a 40°C curing temperature. The successful incorporation of the protein in the carbon ink/solvent composite, while remaining catalytically competent, attests for ccNiR's robustness and suitability for application in screen printed based biosensors. Because the direct electrochemical reduction of molecular oxygen occurs when electroanalytical measurements are performed at the negative potentials required to activate ccNiR (ca.-0.4V vs Ag/AgCl), an oxygen scavenging system based on the coupling of glucose oxidase and catalase activities was successfully used. This enabled the quantification of nitrite in different samples (milk, water, plasma and urine) in a straightforward way and with small error (1-6%). The sensitivity of the biosensor towards nitrite reduction under optimized conditions was 0.55 A M(-1) cm(-2) with a linear response range 0.7-370 μM.

Haemoglobin variants and anaemia among pre-school/school children in north-east Brazil

In this study we investigated the presence of haemoglobin (Hb) variants and anaemia among 382 pre-school/school children from Bahia State, Brazil, a state where intermixing involving people from African origin is the highest in the country. Hb variants were investigated by cellulose acetate electrophoresis at alkaline pH. The pattern obtained was confirmed by citrate agar electrophoresis at pH 6.2. From the 382 children investigated, 79 (20.7%) had Hb variants: 47 (59.5%) had HbAS, 28 (35.4%) HbAC, 3 (3.8%) HbSC and 1 (1.3%) HbCC. Two hundred and fourteen children had anaemia. From these, 39 had microcytosis and 14 had low values of ferritin (<12 ng/ml). We cannot exclude thalassaemia among the children with microcytosis and hypochromia because it was not investigated. The majority of the children showed high mean values of ferritin, suggestive of subclinical infection. There was no difference when we compared the prevalence of anaemia among children with Hb variants (65.8%) and those without Hb variants (53.5%) (P = 0.06). These data demonstrate that Hb variants and anaemia are probably important public health problems in north-east Brazil.

Comparison of positivity frequency of bcl-2 expression in prostate adenocarcinoma with low and high Gleason score

CONTEXT

Multiple genetic and epigenetic factors have been implicated in the oncogenesis and progression of prostate cancer. The major difficulty is in that the clinical management stems from the reality that reliable and accurate prognostic biomarkers are not available and that effective treatment regimens forming hormone-resistant prostate cancers are yet to be developed. Among the most important regulators of apoptosis and programmed cell death is the bcl-2 gene and its related proteins. Elevated levels of bcl-2 protein may contribute to the progression of prostate cancers to a metastatic and hormone-insensitive state characterized by poor responses to chemotherapy.

OBJECTIVE

To characterize the expression of bcl-2 proteins as a prognostic factor in humans.

DESIGN

A retrospective approach.

SETTING

Urology section, Federal University of São Paulo. DIAGNOSTIC TEST USED: Immunohistochemical analysis using bcl-2 protein antibody and normal staining by hematoxylin-eosin.

MAIN MEASUREMENTS

Prognostic relations and protein expression were evaluated considering the total sample (28) divided into two groups, high (8 to 10) and low (2 to 4), separated according to the histological differentiation grade (Gleason score) with 10 and 18 samples, respectively.

RESULTS

The differentiation of grade into two groups separated according to the Gleason score in low and high types presented different bcl-2 expression (P < 0.001).

CONCLUSION

The higher frequency of bcl-2 immunostaining in tumor samples was observed in association with more advanced Gleason scores and suggests that an increase in the ratio of this anti-apoptotic protein often occurs during progression of prostate cancers.

Synchronous bilateral carcinoma of the adrenal gland: 2 case reports

The existence of synchronous bilateral adrenal masses is an uncommon condition except in the relatively more frequent cases of pheochromocytoma or metastatic tumors. Two cases of synchronous nonfunctioning bilateral adrenal cortex carcinoma, removed during the same operation, are described. The patients currently are receiving hormonal supplementation, and were well 16 and 12 months postoperatively.

Lower esophageal strictures, benign or malignant?

In a retrospective study of 93 patients with benign peptic strictures, and 73 patients with malignancy of the lower third of the esophagus, 93% of benign strictures were associated with a hiatal hernia, and 4% without. In malignancy the majority were without hernia. The results provide a statistical basis for strong suspicion of malignancy in a lower esophageal stricture not accompanied by a hiatal hernia.