Dexamethasone alters TNF-alpha expression in retinopathy

TNF-alpha has been found in the retina. Hyperoxia and hypoxia regulate TNF-alpha expression. TNF-alpha is an important factor in inflammation and angiogenesis. Dexamethasone inhibits TNF-alpha production. Changes in TNF-alpha expression in the retina may play an important role in the development of oxygen-induced retinopathy. Oxygen-induced retinopathy was produced in C57BL6 mice by exposure to 75% oxygen at Postnatal Day 7 (P7) for 5 days and the mice recovered in room air until Day 17 (P17). Dexamethasone was administered at 0.5 mg/kg/day once daily subcutaneously during the 5 days of oxygen exposure. TNF-alpha expression was evaluated at Day 7 prior to oxygen exposure, at Day 12 (P12) immediately upon removal from oxygen, and at Day 17, the time of maximal vasoproliferation by RT-PCR. TNF-alpha is developmentally regulated in the retinae of C57BL6 mice. From P7 to P12, there is a 3-fold increase in TNF-alpha expression and from P7 to P17 there is a 2.7-fold increase. There was 2.7-fold suppression in expression immediately following oxygen exposure at P12. The expression was dramatically increased at P17, the time of maximal vasoproliferation. Dexamethasone inhibited the expression of TNF-alpha at P17 by 6.4-fold. At this dose, it also suppressed the baseline TNF-alpha expression in the mouse model. In summary, TNF-alpha is altered in the development of oxygen-induced retinopathy in the mouse. It increased markedly during the vasoproliferative phase and was suppressed by dexamethasone. Modulation of TNF-alpha expression may provide a potential site of action for future therapeutic targets.     

Use of 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyl Tetrazolium Bromide for Rapid Detection of Rifampin-Resistant Mycobacterium tuberculosis

We describe a test which uses the ability of viable cells to reduce 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) to detect resistance to a bactericidal drug, rifampin, in in vitro-cultured Mycobacterium tuberculosis. The assay shows a linear relationship between the number of viable bacteria and the ability to reduce MTT. Dead mycobacteria were unable to reduce MTT. Rifampin-sensitive M. bovis (BCG) and M. tuberculosis exposed to rifampin showed a rifampin concentration-dependent inhibition of the ability to reduce MTT, while the resistant strains were unaffected. The inhibition of MTT reduction after treatment with rifampin paralleled the reduction in the number of CFU. By using mixing experiments in which the population percentages of rifampin-sensitive and -resistant strains were varied, the assay could detect the presence of rifampin resistance in the mixture when at least 1% of the bacterial population was composed of drug-resistant strains. The assay is cheap, can be visually read, and requires less than 3 days to obtain susceptibility results. The total time required to obtain results, from the time sputum is received in the laboratory, is, in most cases, less than 4 to 5 weeks, which is the time required for primary culture of the bacteria. The MTT assay could, in combination with a test to detect resistance to isoniazid, be a cheap and rapid screening method for multidrug-resistant M. tuberculosis that is affordable even by low-income countries where tuberculosis is a major public health problem.     

Synthesis of nitrogen doped carbon quantum dots/magnetite nanocomposites for efficient removal of methyl blue dye pollutant from contaminated water

As a remedy for environmental pollution, a simple synthesis approach has been developed to prepare nitrogen doped carbon quantum dot/magnetite nanocomposites (Fe₃O₄@NCQDs NCs) using non-toxic and cost effective lemon juice as precursor for removal of organic dye pollutant. Fe₃O₄@NCQDs NCs were characterized by using UV-Vis spectroscopy, FTIR, XRD, FESEM, EDS, TEM, VSM and TGA/DTA. TEM results show spherical shaped Fe₃O₄@NCQDs NCs with an average particle size of 5 nm. Batch adsorption studies were done to investigate the tendency of the nanocomposites to remove representative methyl blue (MB) dye from aqueous solution. The effects of MB dye concentration, dosage of Fe₃O₄@NCQDs NC adsorbent, pH, contact time and temperature were optimized by varying one variable while all the other parameters were kept constant. The experiment showed rapid removal of MB dye within 20 minutes with an adsorption efficiency of over 90.84% under optimum conditions. The adsorption process fits the Freundlich isotherm model well with R² and n values of 0.993 and 1.842, respectively, at 298 K indicating the feasibility of the adsorption process. The adsorption process is spontaneous and involves exothermic behaviour as confirmed by thermodynamic studies. From a kinetic study, it was found that the pseudo-second order model is more suitable to describe the adsorption process than the pseudo-first order model for adsorption of MB dye onto Fe₃O₄@NCQDs NCs.

Herein, we report the green synthesis of magnetic, nitrogen doped carbon quantum dot/Fe₃O₄ NPs using aqueous lemon extract for the efficient removal of organic dye pollutants from contaminated water.     

Inter-Rater Agreement between Trachoma Graders: Comparison of Grades Given in Field Conditions versus Grades from Photographic Review

ABSTRACT

Purpose: Trachoma surveillance is most commonly performed by direct observation, usually by non-ophthalmologists using the World Health Organization (WHO) simplified grading system. However, conjunctival photographs may offer several benefits over direct clinical observation, including the potential for greater inter-rater agreement. This study assesses whether inter-rater agreement of trachoma grading differs when trained graders review conjunctival photographs compared to when they perform conjunctival examinations in the field.

Methods: Three trained trachoma graders each performed an independent examination of the everted right tarsal conjunctiva of 269 children aged 0–9 years, and then reviewed photographs of these same conjunctivae in a random order. For each eye, the grader documented the presence or absence of follicular trachoma (TF) and intense trachomatous inflammation (TI) according to the WHO simplified grading system.

Results: Inter-rater agreement for the grade of TF was significantly higher in the field (kappa coefficient, κ, 0.73, 95% confidence interval, CI 0.67–0.80) than by photographic review (κ?=?0.55, 95% CI 0.49–0.63; difference in κ between field grading and photo grading 0.18, 95% CI 0.09–0.26). When field and photographic grades were each assessed as the consensus grade from the three graders, agreement between in-field and photographic graders was high for TF (κ?=?0.75, 95% CI 0.68–0.84).

Conclusions: In an area with hyperendemic trachoma, inter-rater agreement was lower for photographic assessment of trachoma than for in-field assessment. However, the trachoma grade reached by a consensus of photographic graders agreed well with the grade given by a consensus of in-field graders.     

Assessing the Performance of CareStart Malaria Pf/Pv Combo Test Against Thick Blood Film in the Diagnosis of Malaria in Northwest Ethiopia

Bivalent rapid diagnostic tests are promising diagnostic tools for Plasmodium falciparum and P. vivax. Their diagnostic performance was evaluated against thick blood smear to assist national malaria control programs. A cross-sectional study was conducted to evaluate the performance of CareStart against thick blood smears among 398 acute febrile patients visiting the Felegeselam Health Center in December of 2011. Thick blood smears were examined under 100× objectives to diagnose Plasmodium species. Similarly, CareStart Malaria Pf/Pv Combo Test was performed as per the manufacturer''s instruction. The ability of CareStart Malaria Pf/Pv Combo Test to diagnose Plasmodium malaria was very good, with 99.8% (95% confidence interval = 97.7–100%) sensitivity and 97.7% (95% confidence interval = 94.6–99.1%) specificity. The sensitivity and specificity of the CareStart Test is comparable with the thick blood smear in diagnosing malaria. Hence, it is preferable to use the CareStart Malaria Pf/Pv Combo Test instead of microscopy in areas where microscopic diagnosis is limited.