Bloodstream Infection among Children Presenting to a General Hospital Outpatient Clinic in Urban Nepal

Background

There are limited data on the etiology and characteristics of bloodstream infections in children presenting in hospital outpatient settings in South Asia. Previous studies in Nepal have highlighted the importance of murine typhus as a cause of febrile illness in adults and enteric fever as a leading bacterial cause of fever among children admitted to hospital.

Methods

We prospectively studied a total of 1084 febrile children aged between 2 months and 14 years presenting to a general hospital outpatient department in Kathmandu Valley, Nepal, over two study periods (summer and winter). Blood from all patients was tested by conventional culture and by real-time PCR for Rickettsia typhi.

Results

Putative etiological agents for fever were identified in 164 (15%) patients. Salmonella enterica serovar Typhi (S. Typhi) was identified in 107 (10%), S. enterica serovar Paratyphi A (S. Paratyphi) in 30 (3%), Streptococcus pneumoniae in 6 (0.6%), S. enterica serovar Typhimurium in 2 (0.2%), Haemophilus influenzae type b in 1 (0.1%), and Escherichia coli in 1 (0.1%) patient. S. Typhi was the most common organism isolated from blood during both summer and winter. Twenty-two (2%) patients were PCR positive for R. typhi. No significant demographic, clinical and laboratory features distinguished culture positive enteric fever and murine typhus.

Conclusions

Salmonella infections are the leading cause of bloodstream infection among pediatric outpatients with fever in Kathmandu Valley. Extension of immunization programs against invasive bacterial disease to include the agents of enteric fever and pneumococcus could improve the health of children in Nepal.     

Protein S-nitrosylation: Role for nitric oxide signaling in neuronal death

Background

One of the signaling mechanisms mediated by nitric oxide (NO) is through S-nitrosylation, the reversible redox-based modification of cysteine residues, on target proteins that regulate a myriad of physiological and pathophysiological processes. In particular, an increasing number of studies have identified important roles for S-nitrosylation in regulating cell death.

Scope of review

The present review focuses on different targets and functional consequences associated with nitric oxide and protein S-nitrosylation during neuronal cell death.

Major conclusions

S-Nitrosylation exhibits double-edged effects dependent on the levels, spatiotemporal distribution, and origins of NO in the brain: in general Snitrosylation resulting from the basal low level of NO in cells exerts anti-cell death effects, whereas S-nitrosylation elicited by induced NO upon stressed conditions is implicated in pro-cell death effects.

General Significance

Dysregulated protein S-nitrosylation is implicated in the pathogenesis of several diseases including degenerative diseases of the central nervous system (CNS). Elucidating specific targets of S-nitrosylation as well as their regulatory mechanisms may aid in the development of therapeutic intervention in a wide range of brain diseases.     

Differential degradation of photosystem I subunits under iron deficiency in rice

Rice (Oryza sativa) is one of the staple foods of the world. Iron (Fe) deficiency is a major abiotic stress factor that contributes world-wide to losses in crop yield and decline in nutritional quality. As cofactor for many enzymes and proteins, iron is an essential element. It plays a pivotal role in chlorophyll (Chl) biosynthesis, and iron deficiency may result in decreased Chl production and, thus, reduced photosynthetic capacity. Photosystem I (PSI) is a prime target of iron deficiency because of its high iron content (12 Fe per PS). To understand the protein level changes in the light-harvesting complex (LHC) of PSI (LHCI) under iron deficiency, rice seedlings were grown in Hoagland's nutrient medium with and without Fe. Chlorophyll content and photosynthetic efficiency decreased under iron deficiency. Protein gel blots probed with antibodies against the PSI core and Lhca 1-4 proteins revealed that the core subunits PsaA and PsaB remained stable under iron deficiency, whereas PsaC and PsaD decreased by about 50%, and PsaE was completely degraded. Among the LHCI subunits, Lhca1 and Lhca2 decreased by 40 and 50%, respectively, whereas Lhca3 and Lhca4 were completely degraded. We propose that the dissociation of LHCI subunits may be due to increased levels of reactive oxygen species, which is suggested by the increased activity of superoxide dismutase.     

Chronic high-carbohydrate, high-fat feeding in rats induces reversible metabolic, cardiovascular, and liver changes

Age-related physiological changes develop at the same time as the increase in metabolic syndrome in humans after young adulthood. There is a paucity of data in models mimicking chronic diet-induced changes in human middle age and interventions to reverse these changes. This study measured the changes during chronic consumption of a high-carbohydrate (as cornstarch), low-fat (C) diet and a high-carbohydrate (as fructose and sucrose), high-fat (H) diet in rats for 32 wk. C diet feeding induced changes without metabolic syndrome, such as disproportionate increases in total body lean and fat mass, reduced bone mineral content, cardiovascular remodeling with increased systolic blood pressure, left ventricular and arterial stiffness, and increased plasma markers of liver injury. H diet feeding induced visceral adiposity with reduced lean mass, increased lipid infiltration in the skeletal muscle, impaired glucose and insulin tolerance, cardiovascular remodeling, hepatic steatosis, and increased infiltration of inflammatory cells in the heart and the liver. Chia seed supplementation for 24 wk attenuated most structural and functional modifications induced by age or H diet, including increased whole body lean mass and lipid redistribution from the abdominal area, and normalized the chronic low-grade inflammation induced by H diet feeding; these effects may be mediated by increased metabolism of anti-inflammatory n-3 fatty acids from chia seed. These results suggest that chronic H diet feeding for 32 wk mimics the diet-induced cardiovascular and metabolic changes in middle age and that chia seed may serve as an alternative dietary strategy in the management of these changes.     

Complexity of rice Hsp100 gene family: lessons from rice genome sequence data

Elucidation of genome sequence provides an excellent platform to understand detailed complexity of the various gene families. Hsp100 is an important family of chaperones in diverse living systems. There are eight putative gene loci encoding for Hsp100 proteins in Arabidopsis genome. In rice, two full-length Hsp100 cDNAs have been isolated and sequenced so far. Analysis of rice genomic sequence by in silico approach showed that two isolated rice Hsp100 cDNAs correspond to Os05g44340 and Os02g32520 genes in the rice genome database. There appears to be three additional proteins (encoded by Os03g31300, Os04g32560 and Os04g33210 gene loci) that are variably homologous to Os05g44340 and Os02g32520 throughout the entire amino acid sequence. The above five rice Hsp100 genes show significant similarities in the signature sequences known to be conserved among Hsp100 proteins. While Os05g44340 encodes cytoplasmic Hsp100 protein, those encoded by the other four genes are predicted to have chloroplast transit peptides.     

A 1.5-Mb-resolution radiation hybrid map of the cat genome and comparative analysis with the canine and human genomes

We report the construction of a 1.5-Mb-resolution radiation hybrid map of the domestic cat genome. This new map includes novel microsatellite loci and markers derived from the 2X genome sequence that target previous gaps in the feline-human comparative map. Ninety-six percent of the 1793 cat markers we mapped have identifiable orthologues in the canine and human genome sequences. The updated autosomal and X-chromosome comparative maps identify 152 cat-human and 134 cat-dog homologous synteny blocks. Comparative analysis shows the marked change in chromosomal evolution in the canid lineage relative to the felid lineage since divergence from their carnivoran ancestor. The canid lineage has a 30-fold difference in the number of interchromosomal rearrangements relative to felids, while the felid lineage has primarily undergone intrachromosomal rearrangements. We have also refined the pseudoautosomal region and boundary in the cat and show that it is markedly longer than those of human or mouse. This improved RH comparative map provides a useful tool to facilitate positional cloning studies in the feline model.     

Protein accumulation in the germinating Uromyces appendiculatus uredospore

Uromyces appendiculatus is a rust fungus that causes disease on beans. To understand more about the biology of U. appendiculatus, we have used multidimensional protein identification technology to survey proteins in germinating asexual uredospores and have compared this data with proteins discovered in an inactive spore. The relative concentrations of proteins were estimated by counting the numbers of tandem mass spectra assigned to peptides for each detected protein. After germination, there were few changes in amounts of accumulated proteins involved in glycolysis, acetyl Co-A metabolism, citric acid cycle, ATP-coupled proton transport, or gluconeogenesis. Moreover, the total amount of translation elongation factors remained high, supporting a prior model that suggests that germlings acquire protein translation machinery from uredospores. However, germlings contained a higher amount of proteins involved in mitochondrial ADP:ATP translocation, which is indicative of increased energy production. Also, there were more accumulating histone proteins, pointing to the reorganization of the nuclei that occurs after germination prior to appressorium formation. Generally, these changes are indicative of metabolic transition from dormancy to germination and are supported by cytological and developmental models of germling growth.     

L-asparaginase: a promising chemotherapeutic agent

This article comprises detailed information about L-asparaginase, encompassing topics such as microbial and plant sources of L-asparaginase, treatment with L-asparaginase, mechanism of action of L-asparaginase, production, purification, properties, expression and characteristics of l-asparaginase along with information about studies on the structure of L-asparaginase. Although L-asparaginase has been reviewed by Savitri and Azmi (2003), our effort has been to include recent and updated information about the enzyme covering new aspects such as structural modification and immobilization of L-asparaginase, recombinant L-asparaginase, resistance to L-asparaginase, methods of assay of L-asparagine and L-asparaginase activity using the biosensor approach, L-asparaginase activity in soil and the factors affecting it. Also, side-effects of L-asparaginase treatment in acute lymphoblastic leukemia (ALL) have been discussed in the current review. L-asparaginase has been and is still one of the most widely studied therapeutic enzymes by researchers and scientists worldwide.     

RAD51AP1 mediates RAD51 activity through nucleosome interaction

RAD51-associated protein 1 (RAD51AP1) is a key protein in the homologous recombination (HR) DNA repair pathway. Loss of RAD51AP1 leads to defective HR, genome instability, and telomere erosion. RAD51AP1 physically interacts with the RAD51 recombinase and promotes RAD51-mediated capture of donor DNA, synaptic complex assembly, and displacement-loop formation when tested with nucleosome-free DNA substrates. In cells, however, DNA is packaged into chromatin, posing an additional barrier to the complexities of the HR reaction. In this study, we show that RAD51AP1 binds to nucleosome core particles (NCPs), the minimum basic unit of chromatin in which approximately two superhelical turns of 147 bp double-stranded DNA are wrapped around one histone octamer with no free DNA ends remaining. We identified a C-terminal region in RAD51AP1, including its previously mapped DNA-binding domain, as critical for mediating the association between RAD51AP1 and both the NCP and the histone octamer. Using in vitro surrogate assays of HR activity, we show that RAD51AP1 is capable of promoting duplex DNA capture and initiating joint-molecule formation with the NCP and chromatinized template DNA, respectively. Together, our results suggest that RAD51AP1 directly assists in the RAD51-mediated search for donor DNA in chromatin. We present a model, in which RAD51AP1 anchors the DNA template through affinity for its nucleosomes to the RAD51-ssDNA nucleoprotein filament.