Quantification of parasite density in 200 microscopic fields underestimates the parasitemia level in malaria patients.

The determination of parasitemia in the diagnosis of malaria is a routine practice because it assists the selection of treatment. The techniques used for estimating parasitemia are based on leukocyte counts or on a fixed volume of blood examined in a microscopic field. This study evaluated the concordance between parasitemia estimated by counting parasites in 200 microscopic fields and by counting parasites per 500 leukocytes using the automated leukocyte count as a reference. This study included 403 patients with acute malaria. The parasitemia levels obtained by each method varied greatly. A large discrepancy was observed between the 2 methods with respect to parasitemia results, with 17.6% and 82.4% of the values being overestimates and underestimates, respectively, compared to quantification by the automated leukocyte counts. Thus, these findings reveal the inaccuracy of this method and should be considered by health professionals involved in clinical management of the disease.

Superoxide-dependent uptake of vitamin C in human glioma cells.

Glioblastomas are lethal brain tumors that resist current cytostatic therapies. Vitamin C may antagonize the effects of reactive oxygen species (ROS) generating therapies; however, it is often used to reduce therapy-related side effects despite its effects on therapy or tumor growth. Because the mechanisms of vitamin C uptake in gliomas are currently unknown, we evaluated the expression of the sodium-vitamin C cotransporter (SVCT) and facilitative hexose transporter (GLUT) families in human glioma cells. In addition, as microglial cells can greatly infiltrate high-grade gliomas (constituting up to 45% of cells in glioblastomas), the effect of TC620 glioma cell interactions with microglial-like HL60 cells on vitamin C uptake (Bystander effect) was determined. Although glioma cells expressed high levels of the SVCT isoform-2 (SVCT2), low functional activity, intracellular localization and the expression of the dominant-negative isoform (dnSVCT2) were observed. The increased glucose metabolic activity of glioma cells was evident by the high 2-Deoxy-d-glucose and dehydroascorbic acid (DHA) uptake rates through the GLUT isoform-1 (GLUT1), the main DHA transporter in glioblastoma. Co-culture of glioma cells and activated microglial-like HL60 cells resulted in extracellular ascorbic acid oxidation and high DHA uptake by glioma cells. This Bystander effect may explain the high antioxidative potential observed in high-grade gliomas. This study strongly suggests that the Bystander effect, that is, glioma cell interaction with oxidant-producing microglia, could be an important mechanism for glioma vitamin C loading in the absence of functional sodium-vitamin C cotransporter 2 (SVCT2) expression. The high cellular vitamin C load in glioma cells results from a high uptake of extracellular dehydroascorbic acid (DHA) generated by neighboring microglia. This Bystander effect may explain the high antioxidative potential observed in high-grade gliomas, considering that high-grade gliomas may be the only neoplasm where oxidant-producing microglia can almost equal the number of tumor cells.

Evaluation of bone mechanical strenght and fracture risk assessment (Frax) in patients with hip joint replacement surgery.

BACKGROUND: Fracture risk assessment tools are useful to calculate the long term probability of osteoporotic fracture. However, how it reflects bone quality is unknown. The aim of this study was to correlate the WHO clinical fracture risk assessment tool, FRAX, with bone mechanical properties. METHODS: Six patients submitted to hip replacement surgery, either due to osteoporotic fractures or to osteoarthritis, were evaluated. Bone samples were collected and the mechanical properties assessed by compression tests. Patients' data regarding the presence of clinical risk factors for fracture were registered. Laboratorial assessment of bone metabolic parameters and a dual X-ray absorptiometry(DXA) were done. RESULTS: Analysis of the load-displacement curves showed that patients with fragility fractures (n=4) had low values of elastic modulus, yield load and energy absorbed until yield point. Osteoarthritis patients tend to have a better biomechanical performance.Femoral neck DXA scan was also performed in 3 patients. Fragility fracture patients had a lower bone mineral density than the patients with osteoarthritis. FRAX algorithm was applied and a positive relation was found between FRAX results and biomechanical parameters. Blood bone metabolic markers were within the normal range for all the subjects. CONCLUSIONS: The worse mechanical properties observed in the fragility fracture patients were related to high probability of fracture given by FRAX. These observations, in a very small sample, need further confirmation. However, they suggest that the fracture risk assessment tool, FRAX, may reflect the current mechanical bone behavior of the patient.

Chronic arthritis directly induces quantitative and qualitative bone disturbances leading to compromised biomechanical properties.

OBJECTIVES: Rheumatoid arthritis (RA) is associated with an increased risk of fragility fractures. In RA patients, the direct effect of inflammation on bone is difficult to study because their skeleton is also affected by medication with corticosteroids and other drugs as well as aging and menopause, which contribute to bone fragility. This study used an animal model of chronic arthritis to evaluate the direct impact of chronic inflammation on biomechanical properties and structure of bone. METHODS: In the SKG mouse chronic arthritis model three point bending tests were performed on femoral bones and compression tests on vertebral bodies. Collagen structure was analysed using second-harmonic generation (SHG) imaging with a two-photon microscope, ultramorphology by scanning electron microscopy (SEM) coupled with energy dispersive x-ray spectroscopy (EDS) and bone density using water pycnometer. RESULTS: Arthritic bones had poor biomechanical quality compared to control bones. SHG, SEM and pycnometry disclosed variable signs of impaired collagen organization, poor trabecular architecture and low bone density. CONCLUSION: Present data demonstrate for the first time that chronic inflammation per se, without confounding influence of drugs and aging, leads to impairment of bone biomechanics in terms of stiffness, ductility and ultimate strength (fracture).

Mode of cembranoid action on embryonic muscle acetylcholine receptor.

The mechanism of eupalmerin acetate (EUAC) actions on the embryonic muscle nicotinic acetylcholine receptor (nAChR) in BC3H-1 cells was studied by using whole-cell and single-channel patch-clamp current measurements. With whole-cell currents, EUAC did not act as an agonist on this receptor. Coapplication of 30 microM EUAC with 50 microM, 100 microM, or 500 microM carbamoylcholine (CCh) reversibly inhibited the current amplitude, whereas, with 20 microM CCh, current was increased above control values in the presence of EUAC. EUAC concentration curves (0.01-40 microM) obtained with 100 microM and 500 microM CCh displayed slope coefficients, n(H), significantly smaller than one, suggesting that EUAC bound to several sites with widely differing affinities on the receptor molecule. The apparent rate of receptor desensitization in the presence of EUAC and CCh was either slower than or equal to that obtained with CCh alone. The major finding from single-channel studies was that EUAC did not affect single-channel conductance or the ability of CCh to interact with the receptor. Instead, EUAC acted by increasing the channel closing rate constant. The results are not consistent with the competitive model for EUAC inhibition, with the sequential open-channel block model, or with inhibition by increased desensitization. The data are best accounted for by a model in which EUAC acts by closed-channel block at low concentrations, by positive modulation at intermediate concentrations, and by negative allosteric modulation of the open channel at high concentrations.

Does the photochemical conversion of colchicine into lumicolchicines involve triplet transients? A solvent dependence study.

beta- and gamma-lumicolchicines are photoproducts formed by the cycloisomerization of the tropolone ring of colchicine (COL) alkaloids. The mechanism of the photoconversion, suggested to involve the triplet state, is examined here by studying the effect of the solvent polarity on the lumicolchicine photoisomer ratio. Triplet COL, detected by laser flash photolysis, is quenched by oxygen, but not by transtilbene or 1-methylnaphtalene. Neither the quantum yield of conversion of COL nor the photoproduct ratio was altered by the presence of oxygen. Likewise, energy transfer to COL from triplet acetone produced by either isobutanal/horseradish peroxidase system or tetramethyldioxetane thermolysis failed to provoke photoreaction of COL. Our data argue against the intermediacy of a COL triplet state in the photoisomerization and stress on the role of specific solvent-solute interactions in determining the partitioning of excited singlet state into the beta- and gamma-isomer formation.

[Mitral valvuloplasty with Inoue balloon catheter. Analysis of 112 cases]. / Valvuloplastia mitral com cateter-balão de Inoue. Análise de 112 casos.

PURPOSE: To present immediate results of percutaneous mitral valvuloplasty (PVM) with Inoue balloon for the treatment of mitral stenosis. METHODS: One hundred and twelve consecutive patients mean age 31.26 +/- 9.5 years, 82% females, the majority in functional class III/IV (69%) underwent percutaneous mitral valvuloplasty (PVM) with Inoue balloon. The procedure was undertaken by the transseptal technique. RESULTS: PMV achieved significant reduction in mean left atrial pressure pre 24.57 +/- 5.37 post 12.36 +/- 4.82, mitral gradient pre 15.31 +/- 4.28 post 3.48 +/- 2.09 and increased mitral valve area pre 0.88 +/- 0.12 post 2.0 +/- 0.28 (P < 0.001). An increase of at least 25% of the mitral valve area with a final result greater than 1.5 cm2 was obtained in 96% of the cases. Cardiac tamponade occurred in five cases (4.4%). In 4 a successful treatment was accomplished in the catheterization laboratory. Significant mitral regurgitation was seen in one case (0.9%) and there was one death (0.9%). CONCLUSION: The results of this series attest to the effectiveness of the PMV with Inoue balloon in selected cases of mitral stenosis.

Glomerular disease and human immunodeficiency virus infection in Brazil.

Clinically overt glomerular disease was detected in 6 (1.1%) of 543 patients with HIV infection followed at a Brazilian National Referral Center for AIDS. In 4 cases, glomerulosclerosis was present (focal and segmental in 3, diffuse and global in 1) and rapid progression to terminal renal failure was observed 1-10 months after clinical presentation. The other 2 patients died with normal renal function, and autopsy studies suggested the diagnosis of minimal change disease. Clinically overt glomerular disease was significantly more common among Black patients, whether all the cases with glomerulopathy (p < 0.001) or just the cases with glomerular sclerosis were considered (p = 0.011). Autopsy study of renal fragments from patients without clinical evidence of glomerular disease was additionally performed and revealed the presence of focal and segmental glomerulosclerosis in 3 cases (7.5%). We concluded that a glomerulopathy with clinicopathological features which match the definition of HIV nephropathy can be found among Brazilian patients with HIV infection. Accordingly to what has been described in American series, Brazilian Black patients seem to be at increased risk of the development of that nephropathy.

[Coronary angioplasty using last generation materials. Immediate results]. / Angioplastia coronária utilizando material de última geração. Resultados imediatos.

PURPOSE: To present immediate results of percutaneous transluminal coronary angioplasty (PTCA) with the use of last generation catheter devices. METHODS: 74 patients underwent PTCA mean age 55 years the majority of them with disease of one vessel (92%) and good left ventricular function (88%). There was a total of 80 lesions treated, 26 type A and 54 type B according to the Task Force for Coronary Angioplasty of the American College of Cardiology--American Heart Association Classification. Results were analysed by separate observers: one clinical cardiologist (C), one cardiovascular surgeon (S) and two hemodynamicists (H1, H2). RESULTS: A significant fail in the degree of coronary obstruction was demonstrated post PTCA in the opinion of the observers: C = 83 +/- 10.7/9.0 +/- 14; S = 86 +/- 13.0/9.3 +/- 11; H1 = 88.6 +/- 7.0/8.5 +/- 12; H2 = 88.5 +/- 8.0/8.3 +/- 12 (P less than 0.001). Angiographic success was attained in 94.6% of the cases and the complication rate was low 2.7%. CONCLUSION: The high primary success and the low complication rates seen in this series can be attributed to the careful selection of cases and advanced performance of the catheterization devices that were used.