Mitochondrial oxidative metabolism during respiratory infection in riboflavin deficient mice

Studies in children and mice have shown that respiratory infection alters riboflavin metabolism, resulting in increased urinary loss of this vitamin. This could be due to mobilization of riboflavin from the liver to blood because liver Flavin adenine dinucleotide (FAD) levels were lowered in the mice during infection. To understand the functional implications of lowered hepatic FAD levels during respiratory infection, flavoprotein functions such as oxidative phosphorylation and β-oxidation of the liver mitochondria were examined during infection in mice. Weanling mice were fed either riboflavin-restricted or control diet for 18 days and then injected with a sublethal dose of Klebsiella pneumoniae. During infection, the state 3 respiratory rate with palmitoyl-L-carnitine and glutamate were significantly lowered (27–29%) in the riboflavin-restricted group, whereas in the control group 10% reduction was observed with palmitoyl-L-carnitine as substrate. A 22% reduction in the respiratory control ratio with palmitoyl-L-carnitine as substrate was observed during infection in the riboflavin-restricted group. The β-oxidation of palmitoyl-L-carnitine was significantly lowered (29%) in the riboflavin-restricted infected group. The results of the study suggest that the effects of infection on vital physiologic functions were more pronounced in the riboflavin-restricted mice than in the control mice. © Elsevier Science Inc. 1999     

Effect of cigarette smoke on lipid peroxidation and antioxidant enzymes in albino rat

Effect of cigarette smoke on lipid peroxidation (LPX) and antioxidant enzymes like catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and glutathione-S-transferase (GST) in various organs like brain, heart, lung, liver and kidney of the albino rats exposed to cigarette smoke for 30 min/day for a period of 30 days were assayed. It was observed that the lipid peroxide levels in liver, lung and kidney were enhanced in case of animals exposed to cigarette smoke, whereas brain and heart did not show any change as compared to control animals. The activity of the antioxidant enzymes was also elevated in liver, lung and kidney of the test animals whereas, brain and heart did not show any change in the activities of all of these antioxidant enzymes except glutathione-s-transferase which was increased in brain also. The level of reduced glutathione (GSH) was lowered in liver, lung and kidney of the tested animals when compared with the control animals but there was no significant change in brain and heart. The results of our study suggest that cigarette smoke induces lipid peroxidation in liver, lung and kidney, and the antioxidant enzymes levels were enhanced in order to protect these tissues against the deleterious effect of the oxygen derived free radicals. The depletion of reduced glutathione in these organs could be due to it's utilization by the tissues to mop off the free radicals.     

Beacon interacts with cdc2/cdc28-like kinases

Previously we found elevated beacon gene expression in the hypothalamus of obese Psammomys obesus. Beacon administration into the lateral ventricle of P. obesus stimulated food intake and body weight gain. In the current study we used yeast two-hybrid technology to screen for proteins in the human brain that interact with beacon. CLK4, an isoform of cdc2/cdc28-like kinase family of proteins, was identified as a strong interacting partner for beacon. Using active recombinant proteins and a surface plasmon resonance based detection technique, we demonstrated that the three members of this subfamily of kinases (CLK1, 2, and 4) all interact with beacon. Based on the known sequence and functional properties of beacon and CLKs, we speculate that beacon could either modulate the function of key regulatory molecules such as PTP1B or control the expression patterns of specific genes involved in the central regulation of energy metabolism.     

Self-stabilized CpG DNAs optimally activate human B cells and plasmacytoid dendritic cells

We recently showed that 5'-terminal secondary structures in CpG DNA affect activity significantly more than those at the 3'-end [Biochem. Biophys. Res. Commun. 306 (2003) 948]. The need for an accessible 5'-end of CpG DNA for activity suggested that the receptor reads the DNA sequence from this end. In continuation of these studies, we have designed immunomodulatory oligonucleotides (IMOs), consisting of a nine-mer stimulatory domain, containing a CpG motif and a hairpin-loop structure at the 3'-end, referred to as self-stabilized CpG DNAs. We studied the ability of self-stabilized CpG DNAs to stimulate human B-cell proliferation and interferon-alpha (IFN-alpha) secretion in plasmacytoid dendritic cell (pDC) culture assays. Self-stabilized CpG DNAs activated human B cells and induced plasmacytoid dendritic cells to secrete high levels of IFN-alpha. While both stimulatory and secondary structures in CpG DNAs were required for pDC activation, CpG motifs were sufficient to activate B cells. Interestingly, CpG motifs were not required for activity in the hairpin duplex region. Further modifications of the hairpin duplex region with a mixture of oligodeoxynucleotides and oligo-2'-O-methylribonucleotides in a heteroduplex formation permitted activation of both human B cells and pDCs.     

Genome-wide analysis of mariner-like transposable elements in rice reveals complex relationships with stowaway miniature inverted repeat transposable elements (MITEs)

Stowaway is a superfamily of miniature inverted repeat transposable elements (MITEs) that is widespread and abundant in plant genomes. Like other MITEs, however, its origin and mode of amplification are poorly understood. Several lines of evidence point to plant mariner-like elements (MLEs) as the autonomous partners of the nonautonomous Stowaway MITEs. To better understand this relationship, we have taken advantage of the nearly complete genome sequences of two rice subspecies to generate the first inventory of virtually all MLEs and Stowaway families coexisting in a single plant species. Thirty-four different MLEs were found to group into three major clades and 25 families. More than 22,000 Stowaway MITEs were identified and classified into 36 families. On the basis of detailed sequence comparisons, MLEs were confirmed to be the best candidate autonomous elements for Stowaway MITEs. Surprisingly, however, sequence similarity between MLE and Stowaway families was restricted to the terminal inverted repeats (TIRs) and, in a few cases, to adjacent subterminal sequences. These data suggest a model whereby most of the Stowaway MITEs in rice were cross-mobilized by MLE transposases encoded by distantly related elements.     

Multiple mechanisms compensate to enhance tumor-protective CD8(+) T cell response in the long-term despite poor CD8(+) T cell priming initially: comparison between an acute versus a chronic intracellular bacterium expressing a model antigen

We evaluated CD8(+) T cell responses against the dominant CTL epitope, OVA(257-264), expressed by an acute (Listeria monocytogenes (LM) OVA) vs a chronic pathogen (Mycobacterium bovis bacillus Calmette-Guérin (BCG) OVA) to reveal the influence on CD8(+) T cell memory and consequent protection against a challenge with OVA-expressing tumor cells. Infection with lower doses of both pathogens resulted in stronger bacterial growth but weaker T cell memory indicating that memory correlates with pathogen dose but not with bacterial expansion. The CD8(+) T cell response induced by LM-OVA was helper T cell-independent and was characterized by a rapid effector response followed by a rapid, but massive, attrition. In contrast, BCG-OVA induced a delayed and weak response that was compensated for by a longer effector phase and reduced attrition. This response was partly dependent on CD4(+) T cells. CD8(+) T cell response induced by BCG-OVA, but not LM-OVA, was highly dependent on pathogen persistence to compensate for the weak initial CD8(+) T cell priming. Despite a stronger initial T cell response with LM-OVA, BCG-OVA provided more effective tumor (B16OVA) control at both local and distal sites due to the induction of a persistently activated acquired, and a more potent innate, immunity.     

Screening for homozygosity by descent in families with autosomal recessive retinitis pigmentosa

Retinitis pigmentosa (RP) is a genetically heterogeneous disease and an important cause of blindness in the state of Andhra Pradesh in India. In an attempt to identify the disease locus in families with the recessive form of the disease, we used the approach of screening for homozygosity by descent in offspring of consanguineous and nonconsanguineous families with RP. Microsatellite markers closely flanking 21 known candidate genes for RP were genotyped in parents and affected offspring to determine whether there was homozygosity at these loci that was shared by affected individuals of a family. This screening approach may be a rapid preliminary method to test known loci for possible cosegregation with disease.     

A novel noncollagenous protein encoded by an alternative transcript of the chick type III collagen gene is expressed in cartilage,bone and muscle

RanBP1, a velocardiofacial syndrome/DiGeorge syndrome candidate gene, is expressed in the frontonasal processes, branchial arches, aortic arches, and limb buds. At these sites, RanBP1 apparently coincides with neural crest-derived mesenchymal cells. In addition, RanBP1 is expressed in the forebrain as well as in hindbrain regions previously associated with crest-derived mesenchymal cells.