The pH dependence of heme pocket hydration and ligand rebinding kinetics in photodissociated carbonmonoxymyoglobin

We monitored the occupancy of a functionally important non-coordinated water molecule in the distal heme pocket of sperm whale myoglobin over the pH range 4.3-9.4. Water occupancy was assessed by using time-resolved spectroscopy to detect the perturbation of the heme visible band absorption spectrum caused by water entry after CO photodissociation ( Goldbeck, R. A., Bhaskaran, S., Ortega, C., Mendoza, J. L., Olson, J. S., Soman, J., Kliger, D. S., and Esquerra, R. M. (2006) Proc. Natl. Acad. Sci. U. S. A. 103, 1254-1259 ). We found that the water occupancy observed during the time interval between ligand photolysis and diffusive recombination decreased by nearly 20% as the pH was lowered below 6. This decrease accounted for most of the concomitant increase in the observed CO bimolecular recombination rate constant, as the lower water occupancy presented a smaller kinetic barrier to CO entry into the pocket at lower pH. These results were consistent with a model in which the distal histidine, which stabilizes the water molecule within the distal pocket by accepting a hydrogen bond, tends to swing out of the pocket upon protonation and destabilize the water occupancy at low pH. Extrapolation of this model to lower pH suggests that the additional increase in ligand association rate constant observed previously in stopped-flow studies at pH 3 may also be due in part to reduced distal water occupancy concomitant with further His64 protonation and coupled protein conformational change.     

Suicide in Nepal: Qualitative Findings from a Modified Case-Series Psychological Autopsy Investigation of Suicide Deaths

South Asia accounts for the majority of the world’s suicide deaths, but typical psychiatric or surveillance-based research approaches are limited due to incomplete vital surveillance. Despite rich anthropological scholarship in the region, such work has not been used to address public health gaps in surveillance and nor inform prevention programs designed based on surveillance data. Our goal was to leverage useful strategies from both public health and anthropological approaches to provide rich narrative reconstructions of suicide events, told by family members or loved ones of the deceased, to further contextualize the circumstances of suicide. Specifically, we sought to untangle socio-cultural and structural patterns in suicide cases to better inform systems-level surveillance strategies and salient community-level suicide prevention opportunities. Using a mixed-methods psychological autopsy approach for cross-cultural research (MPAC) in both urban and rural Nepal, 39 suicide deaths were examined. MPAC was used to document antecedent events, characteristics of persons completing suicide, and perceived drivers of each suicide. Patterns across suicide cases include (1) lack of education (72% of cases); (2) life stressors such as poverty (54%), violence (61.1%), migrant labor (33% of men), and family disputes often resulting in isolation or shame (56.4%); (3) family histories of suicidal behavior (62%), with the majority involving an immediate family member; (4) gender differences: female suicides were attributed to hopeless situations, such as spousal abuse, with high degrees of social stigma. In contrast, male suicides were most commonly associated with drinking and resulted from internalized stigma, such as financial failure or an inability to provide for their family; (5) justifications for suicide were attributions to ‘fate’ and personality characteristics such as ‘stubbornness’ and ‘egoism’; (5) power dynamics and available agency precluded some families from disputing the death as a suicide and also had implications for the condemnation or justification of particular suicides. Importantly, only 1 out of 3 men and 1 out of 6 women had any communication to family members about suicidal ideation prior to completion. Findings illustrate the importance of MPAC methods for capturing cultural narratives evoked after completed suicides, recognizing culturally salient warning signs, and identifying potential barriers to disclosure and justice seeking by families. These findings elucidate how suicide narratives are structured by family members and reveal public health opportunities for creating or supplementing mortality surveillance, intervening in higher risk populations such as survivors of suicide, and encouraging disclosure.     

Ameliorative Effect of Fisetin on Cisplatin-Induced Nephrotoxicity in Rats via Modulation of NF-κB Activation and Antioxidant Defence

Nephrotoxicity is a dose-dependent side effect of cisplatin limiting its clinical usage in the field of cancer chemotherapy. Fisetin is a bioactive flavonoid with recognized antioxidant and anti-inflammatory properties. In the present study, we investigated the potential renoprotective effect and underlying mechanism of fisetin using rat model of cisplatin-induced nephrotoxicity. The elevation in serum biomarkers of renal damage (blood urea nitrogen and creatinine); degree of histopathological alterations and oxidative stress were significantly restored towards normal in fisetin treated, cisplatin challenged animals. Fisetin treatment also significantly attenuated the cisplatin-induced IκBα degradation and phosphorylation and blocked the NF-κB (p65) nuclear translocation, with subsequent elevation of pro-inflammatory cytokine, TNF-α, protein expression of iNOS and myeloperoxidase activities. Furthermore, fisetin markedly attenuated the translocation of cytochrome c protein from the mitochondria to the cytosol; decreased the expression of pro-apoptotic proteins including Bax, cleaved caspase-3, cleaved caspase-9 and p53; and prevented the decline of anti-apoptotic protein, Bcl-2. The cisplatin-induced mRNA expression of NOX2/gp91phox and NOX4/RENOX and the NADPH oxidase enzyme activity were also significantly lowered by fisetin treatment. Moreover, the evaluated mitochondrial respiratory enzyme activities and mitochondrial antioxidants were restored by fisetin treatment. Estimation of platinum concentration in kidney tissues revealed that fisetin treatment along with cisplatin did not alter the cisplatin uptake in kidney tissues. In conclusion, these findings suggest that fisetin may be used as a promising adjunct candidate for cisplatin use.     

Identification of QTLs for Seed Dormancy in Cultivated Peanut Using a Recombinant Inbred Line Mapping Population

Plant Molecular Biology Reporter - Seed dormancy is an important breeding trait for the development of certain types of peanut cultivars. Peanut cultivars with seed dormancy can inhibit preharvest...     

A multiattribute utility evaluation of different methods for the detection of enteric protozoa causing diarrhea in AIDS patients

Background  

Enteric protozoa and sporozoa have emerged as important opportunistic parasites and can cause fatal infections in AIDS patients. The line of treatment being different for them necessitates an accurate and prompt identification of these to avoid empirical treatment. In this study which is the first of its kind from India we did a comprehensive evaluation of different techniques, comparing them on the basis of the attributes like yield, cost, time taken, expertise and infrastructure. For the first time combination of Calcoflour White and DAPI, a nuclear stain, were used to identify Microsporidia spp. Thus, a diagnostic protocol was devised for rapid, sensitive and cost effective identification of the opportunistic enteric protozoa.     

Visceral leishmaniasis: what are the needs for diagnosis, treatment and control?

Visceral leishmaniasis (VL) is a systemic protozoan disease that is transmitted by phlebotomine sandflies. Poor and neglected populations in East Africa and the Indian sub-continent are particularly affected. Early and accurate diagnosis and treatment remain key components of VL control. In addition to improved diagnostic tests, accurate and simple tests are needed to identify treatment failures. Miltefosine, paromomycin and liposomal amphotericin B are gradually replacing pentavalent antimonials and conventional amphotericin B as the preferred treatments in some regions, but in other areas these drugs are still being evaluated in both mono- and combination therapies. New diagnostic tools and new treatment strategies will only have an impact if they are made widely available to patients.     

Chromium (VI) induced changes in growth and root plasma membrane redox activities in pea plants

The effect of chromium (Cr) on growth as well as root plasma membrane redox reactions and superoxide radical production was studied in pea (Pisum sativum L. cv. Azad) plants exposed for 7 days to 20 and 200 μM Cr (VI), respectively, supplied as potassium dichromate. The growth of pea plants declined significantly at 200 μM Cr, as indicated by reduced leaf area and biomass. Relative to the control plants (no Cr exposure), the Cr content of roots increased significantly, both at 20 and 200 μM Cr. Following exposure to 200 μM Cr, there was a significant increase in root lipid peroxidation and hydrogen peroxide (H₂O₂) content, while both the Fv/Fm ratio and chlorophyll content were reduced. Exposure to Cr increased NADPH-dependent superoxide production in pea root plasma membrane vesicles, with the effect being more significant at 200 μM Cr than at 20 μM Cr. Treatment with Cr rapidly increased the activities of NADPH oxidase: relative to the controls, plants exposed to 20 μM Cr showed approximately a 67% increase in activity while there was a threefold increase in those plants exposed to 200 μM Cr. NADH-ferricyanide oxido-reductase activity was found to be inhibited by 16 and 51% at 20 and 200 μM Cr, respectively. The results of this study suggest that exposure to excess Cr damages pea root plasma membrane structure and function, resulting in decreased photosynthesis and poor plant growth.     

Chromium effect on ROS generation and detoxification in pea (Pisum sativum) leaf chloroplasts

Pea plants were exposed to 0, 20, 50, and 100 µM chromium [Cr(VI)] to investigate oxidative stress in isolated chloroplasts. Leaf area and biomass accumulation were significantly reduced at higher Cr supply. Generation of superoxide, hydrogen peroxide, and ·OH radical generation was enhanced in the chloroplasts isolated from Cr-exposed pea plants. Cr(VI) significantly reduced F _v/F _m ratio of chlorophyll (Chl) fluorescence, Chl content, and whole chain electron transport rate. Superoxide dismutase (SOD) activity increased at lower Cr supply while it decreased at higher Cr supply. Ascorbate peroxidase (APX) was found to be most sensitive to Cr stress. Monodehydroascorbate reductase activity remained higher at 20 and 50 µM Cr but decreased at 100 µM Cr. Increased activities of dehydroascorbate reductase (DHAR) and glutathione reductase (GR) in the isolated chloroplasts were observed during the initial 3 days of Cr exposure of pea plants. Activities of DHAR and GR were increased up to day 3 only. Ascorbate and glutathione (GSH) pools showed similar decrease that was more evident in the GSH pool as the duration of Cr treatment increased. Observed changes in reactive oxygen species concentration, photosynthetic characteristics, and antioxidant system indicate that chloroplasts in Cr-exposed pea plants are an important target of oxidative stress.     

Doppler ultrasound scoring to predict chemotherapeutic response in advanced breast cancer

Background

Von Hippel-Lindau (VHL) disease is an autosomal dominant inherited disease. It is relatively recent that type 2C was identified as a separate group solely presenting with pheochromocytomas. As an illustration, an interesting case is presented of a pregnant woman with refractory hypertension. It proved to be the first manifestation of bilateral pheochromocytomas. The family history may indicate the diagnosis, but only identification of a germ line mutation in the DNA of a patient will confirm carriership.

Case presentation

A 27 year pregnant patient with intra uterine growth retardation presented with hypertension and pre-eclampsia. Magnetic resonance imaging revealed bilateral adrenal pheochromocytoma. She underwent laparoscopic adrenelectomy and a missense mutation (Gly93Ser) in exon 1 of the VHL gene on chromosome 3 (p25 - p26) was shown in the patient, her father and her daughter confirming the diagnosis of VHL.

Conclusion

In almost all VHL families molecular genetic analysis of DNA will demonstrate an inherited mutation. Because of the involvement in several organs, periodic clinical evaluation should take place in a well coordinated, multidisciplinary setting. VHL disease can be classified into several subtypes. VHL type 2C patients present with pheochromocytomas without evidence of haemangioblastomas in the central nervous system and/or retina and a low risk of renal cell carcinoma. Therefore, in such families, periodic clinical screening can be focussed on pheochromocytomas.