Partial purification of acid phosphomonoesterase in axenically grown Entamoeba histolytica NIH-200.

Entamoeba histolytica possesses significant acid phosphatase activity as compared to alkaline phosphatase activity. The acid phosphatase activity in the amoebic cells eluted at higher saline concentration as three distinct peaks at 200, 300 and 400 mM sodium chloride.     

Gangrene of Meckel's diverticulum.

Gangrene of Meckel's diverticulum is uncommon and its pre-operative diagnosis is difficult. We report three cases with different presentations--simulating acute appendicitis, intestinal obstruction, and strangulation of the bowel.     

Sequence variation in the 3'-untranslated region of the dopamine transporter gene and attention-deficit hyperactivity disorder (ADHD).

The dopamine transporter gene (DAT1) has been reported to be associated with attention-deficit hyperactivity disorder (ADHD) in a number of studies [Cook et al. (1995): Am J Human Genet 56(4):9993-998; Gill et al. (1997): Mol Psychiatry 2(4):311-313; Waldman et al. (1998): Am J Human Genet 63(6):1767-1776; Barr et al. (2001): Biol Psychiatry 49(4):333-339; Curran et al. (2001): Mol Psychiatry 6(4):425-428; Chen et al. (2003): Mol Psychiatry 8(4):393-396]. Specifically, the 10-repeat allele of the 40-bp variable number of tandem repeats (VNTR) polymorphism located in the 3' untranslated region (UTR) of the gene has been found to be associated with ADHD. There is evidence from in vitro studies indicating that variability in the repeat number, and sequence variation in the 3'-UTR of the DAT1 gene may influence the level of the dopamine transporter protein [Fuke et al. (2001): Pharmacogenomics J 1(2):152-156; Miller and Madras (2002): Mol Psychiatry 7(1):44-55]. In this study, we investigated whether DNA variation in the DAT1 3'UTR contributed to ADHD by genotyping DNA variants around the VNTR region in a sample of 178 ADHD families. These included a MspI polymorphism (rs27072), a DraI DNA change (T/C) reported to influence DAT1 expression levels, and a BstUI polymorphism (rs3863145) in addition to the VNTR. We also screened the VNTR region by direct resequencing to determine if there was sequence variation within the repeat units that could account for the association. Our results indicate that DAT1 is associated with ADHD in our sample but not with alleles of the VNTR polymorphism. We did not find any variation in the sequence for either the 10- or 9-repeat alleles in the probands screened nor did we observe the reported DraI (T/C) variation. Our results therefore refute the possibility of the reported DraI variation or alleles of the VNTR as the functional variants contributing to the disorder.     

Effects of recombination rate and gene density on transposable element distributions in Arabidopsis thaliana

Transposable elements (TEs) comprise a major component of eukaryotic genomes, and exhibit striking deviations from random distribution across the genomes studied, including humans, flies, nematodes, and plants. Although considerable progress has been made in documenting these patterns, the causes are subject to debate. Here, we use the genome sequence of Arabidopsis thaliana to test for the importance of competing models of natural selection against TE insertions. We show that, despite TE accumulation near the centromeres, recombination does not generally correlate with TE abundance, suggesting that selection against ectopic recombination does not influence TE distribution in A. thaliana. In contrast, a consistent negative correlation between gene density and TE abundance, and a strong under-representation of TE insertions in introns suggest that selection against TE disruption of gene expression is playing a more important role in A. thaliana. High rates of self-fertilization may reduce the importance of recombination rate in genome structuring in inbreeding organisms such as A. thaliana and Caenorhabditis elegans.     

Cholinergic and serotonergic alterations in the rat hippocampus following trimethyltin exposure and fetal neural transplantation

The M2 receptor (M2-mAChR) is quantitatively the dominant muscarinic subtype in animal bladders. The alterations in its protein quantity and biosynthesis during diabetic cystopathy were investigated. Three-month-old male Wistar rats were divided into two groups: (1) 2-week-old diabetics; and (2) normoglycemic control rats. Diabetes was induced by single intravenous injection of 60 mg/kg streptozotocin. The amount of M2 receptor protein in the rat bladder body tissue was measured by Western immunoblotting using monoclonal antibodies. For determination of M2 muscarinic receptor mRNA in the bladder tissue, the method of Northern blotting was employed. The results of the Western immunoblotting showed that the amount of M2-mAChR protein in the diabetic bladder was significantly increased by 40.0 +/- 6.2% when compared with the control bladder (P < 0.05, n = 8). The Northern blotting demonstrated a 69.3 +/- 8.5% increase of the M2-mAChR mRNA in the diabetic bladder (P < 0.05, n = 8). The findings of the present study demonstrated an up-regulation of M2-mAChR biosynthesis in the diabetic urinary bladder. This phenomenon could lead to increased reactivity to acetylcholine and thus results in detrusor instability.     

Cadmium and zinc induced nuclear changes in the liver and kidney of rats

When administered to animals cadmium is known to accumulate in the liver and kidney causing indentifiable toxicity. However, its binding with cell sap and nucleus and effects on their constituents are poorly known. Since nuclear changes reflect some of the metabolic disturbances and are of value in diagnosis, an attempt has been made to analyse their morphology and chemistry in the liver and kidney of rat after individual and combined treatment with Cd and Zn. Present observations clearly show that cadmium inhibits DNA synthesis by blocking the formation of the enzyme thymidine triphosphate which is prerequisite for DNA synthesis. Zinc exerted a stimulatory effect on DNA and RNA both by increasing the activity of thymidine kinase. Their combined effects were found to be less injurious to the cell. Though these changes could be a secondary or generalized response of nuclei to altered physiological conditions, specific reasons for these changes have been discussed.     

Inverted terminal repeat sequences of adeno-associated virus enhance the antibody and CD8(+) responses to a HIV-1 p55Gag/LAMP DNA vaccine chimera

The immune responses to an HIV-1 p55Gag vaccine encoded as a DNA chimera with the lysosomal associated membrane protein-1 (LAMP) have been examined for the effect of the addition of the inverted terminal repeat (ITR) sequences of the adeno-associated virus (AAV) to the DNA plasmid construct, and of packaging the LAMP/gag gene as a recombinant AAV vector (rAAV). DNA plasmids encoding Gag and the LAMP/Gag protein chimera were constructed in two vectors, the pcDNA3.1 and a corresponding plasmid containing the ITR sequences (pITR) flanking the expression elements of the plasmid, and the pITR LAMP/gag DNA plasmid was encapsidated in the rAAV vector. Human 293 cells transfected in vitro with LAMP/gag plasmids either in pcDNA3.1 or pITR produced much Gag protein in cell extracts (1.6 and 2.2 ng of Gag/mg of protein, respectively). The immune responses of mice to immunization with these constructs were examined under three protocols: DNA prime/DNA boost, DNA prime/rAAV boost, and a single rAAV immunization. The results demonstrated that under DNA prime/DNA boost protocol, the "naked" DNA vaccines encoding the LAMP/gag chimera, either as pcDNA3.1 or pITR DNA plasmid constructs, elicited strong CD4(+) T cell responses. In contrast, significantly higher levels of CD8(+) and antibody responses were observed with the pITR-DNA constructs. Immunization with the rAAV vector under the DNA prime/rAAV boost protocol resulted in sustained T cell responses and a markedly increased antibody response, predominantly of the IgG(1) isotype resulting from the activation of the Th2 subset of CD4(+) T cells, that was sustained for at least 5 months after immunization.