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Biomedical subjects

Anand K Srivastava

Publications and source records attributed to Anand K Srivastava.

10 recordsLinked to original sources
PubMed2007

Sequence variants within exon 1 of MECP2 occur in females with mental retardation.

A new splice variant of the Rett syndrome gene, MECP2, was recently identified, that includes coding sequence from exon 1, and is the predominant transcript in the central nervous system. This sequence encodes polyalanine and polyglycine stretches within the N-terminal portion of MeCP2, and may confer novel functional properties to the protein. We screened autism, mental retardation (MR), and control populations for sequence variation within this region, and identified variation in approximately 1% of MR cases screened (N = 1,410). No variants were identified in the autism sample (N = 401). Most of these variants occur within a trinucleotide repeat region and result in change in number of alanine or glycine residues within the repeat stretches. We suggest some of these variants may be a relatively frequent cause of non-specific MR or developmental delay.

Adult↗
PubMed2006

Carriers and patients with muscle-eye-brain disease can be rapidly diagnosed by enzymatic analysis of fibroblasts and lymphoblasts.

We report a new fibroblast and lymphoblast based protein O-mannosyl beta-1,2-N-acetylglucosaminyltransferase 1 enzymatic assay, which allows rapid and accurate diagnosis of carriers and patients with muscle-eye-brain type of congenital muscular dystrophy. Seven patients with genetically confirmed muscle-eye-brain disease were assayed for protein O-mannosyl beta-1,2-N-acetylglucosaminyltransferase 1 enzyme activity. In three patients and their heterozygous parents, the assays were done on EBV-transformed lymphoblasts, in another three patients they were done on cultured fibroblasts and in the last patient on both fibroblasts and lymphoblasts. Cultured fibroblasts and lymphoblasts from the muscle-eye-brain patients showed a highly significant decrease in protein O-mannosyl beta-1,2-N-acetylglucosaminyltransferase 1 activity relative to controls. The residual protein O-mannosyl beta-1,2-N-acetylglucosaminyltransferase 1 level in fibroblasts (average 0.11 nmoles/h per mg) was about 13% of normal controls. The ratio of protein O-mannosyl beta-1,2-N-acetylglucosaminyltransferase 1 activity to the activity of a glycosyltransferase control (N-acetylglucosaminyltransferase 1; GnT1) in fibroblasts was on average 0.006 in muscle-eye-brain patients and 0.045 in controls. The average residual protein O-mannosyl beta-1,2-N-acetylglucosaminyltransferase 1 level in lymphoblasts was 15% of normal controls. The average ratio of protein O-mannosyl beta-1,2-N-acetylglucosaminyltransferase 1/GnT1 activity was 0.007 in muscle-eye-brain patients, 0.026 in heterozygous carriers and 0.046 in normal controls. Assay of protein O-mannosyl beta-1,2-N-acetylglucosaminyltransferase 1 activity in fibroblasts and lymphoblasts from muscle-eye-brain carriers and patients provides a rapid and relatively simple diagnostic test for this disease and could be used as a screening test in carriers and patients with complex congenital muscular dystrophy.

Cells, Cultured↗
PubMed2006

Unusual phenotypic expression of an XLRS1 mutation in X-linked juvenile retinoschisis.

X-linked juvenile retinoschisis is a rare progressive vitreoretinal degenerative process that appears in early childhood, results in decreased visual acuity and blindness (if severe), and is caused by various mutations within the XLRS1 gene at Xp22.2. We report an affected family of Western European ancestry with X-linked juvenile retinoschisis. The family was found to carry a 304C-->T substitution in exon 4 of the XLRS1 gene, resulting in an Arg102Trp amino acid substitution. Two of the four available clinical cases in this family were found to carry the mutation. All available mothers of affected males were found to be unaffected carriers of the mutation, a typical feature of X-linked diseases. Two new female carriers, sisters of affected males, were identified and counseled accordingly. Questionnaires on visual functioning were given to the affected family members to examine the psychologic and sociologic impact of X-linked juvenile retinoschisis, which documented an associated stigma even when affected with a "mild" phenotype.

Adult↗
PubMed2004

POMGnT1 gene alterations in a family with neurological abnormalities.

Muscle-eye-brain disease (MEB), is caused by mutations in the POMGnT1 gene. We describe a white family with two siblings affected with congenital hypotonia early-onset glaucoma, and psychomotor delays. Brain magnetic resonance images (MRIs) showed hydrocephalus, bilateral frontal polymicrogyria, abnormal cerebellum, and characteristic flattened dystrophic pons. We identified novel POMGnT1 gene alterations in this family. Both affected siblings were found to be compound hetrozygotes and carried two missense changes inherited from their mother and one missense change (p.R442C) inherited from their father. Our findings further define the phenotypic spectrum of MEB and its occurrence in the US population.

Brain↗
PubMed2003

Inducible mEDA-A1 transgene mediates sebaceous gland hyperplasia and differential formation of two types of mouse hair follicles.

EDA splice isoforms EDA-A1 and EDA-A2 belong to the TNF ligand family and regulate skin appendage formation by activating NF-kappa B- and JNK- promoted transcription. To analyze their action further, we conditionally expressed the isoforms as tetracycline ('Tet')-regulated transgenes in Tabby (EDA-negative) and wild-type mice. Expression of only the mEDA-A1 transgene had two types of effects during embryogenesis: (1) determinative effects on sweat glands and hair follicles. In Tabby mice, one type of hair follicle ('guard hair') was restored, whereas a second type, the dominant undercoat hair follicle ('zigzag') was not; furthermore, the transgene sharply suppressed zigzag hair formation in wild-type mice, with the overall numbers of back hair follicles remaining the same; and (2) trophic effects on sebaceous and Meibomian glands. Marked hyperplasia resulted from expansion of the sebocyte-producing zone in sebaceous glands, with particularly high expression of the transgene and the replication marker PCNA, and correspondingly high production of sebum. The phenotypic effects of mEDA-A1 on sebaceous glands, but not on hair follicles, were reversed when the gene was repressed in adult animals. The results thus reveal both initiating and trophic isoform-specific effects of the EDA gene, and suggest a possible balance of isoform interactions in skin appendage formation.

Animals↗
PubMed2002

EDA targets revealed by skin gene expression profiles of wild-type, Tabby and Tabby EDA-A1 transgenic mice.

Mutations in the EDA gene cause anhidrotic ectodermal dysplasia (EDA), with lesions in skin appendage formation. To begin to analyze EDA pathways, we have used expression profiling on 15,000-gene mouse cDNA microarrays, comparing adult mouse skin from wild-type, EDA-defective (Tabby) mice, and Tabby mice supplemented with the EDA-A1 isoform, which is sufficient to rescue multiple Tabby phenotypes. Given the sensitivity of the current microarray system, 8500 genes (60%) were estimated to be expressed, including transcription factors and growth-regulatory genes that had not previously been identified in skin; but only 24 (0.16%), one-third of them novel, showed significant differences between wild type and Tabby. An additional eight genes not included in the 15,000 gene set were shown to have expression differences by real-time RT-PCR. Sixteen of 32 affected genes were restored significantly toward wild-type levels in EDA-A1 transgenic Tabby mice. Significant up-regulation in Tabby skin was observed for several dermal matrix genes, including Col1a1, Col1a2, Col3a1 and SPARC: In contrast, down-regulation occurred for the NEMO/NF-kappa B pathway, already implicated in skin appendage formation, and even more markedly for a second pathway, JNK/c-jun/c-fos and their target genes, that has not previously been clearly associated with skin development. These data are consistent with the regulation of the NF-kappa B pathway by EDA, and support its involvement in the regulation of the JNK pathway as well.

Animals↗
PubMed2002

AGTR2 mutations in X-linked mental retardation.

Two angiotensin II (Ang II)-specific receptors, AGTR1 and AGTR2, are expressed in the mammalian brain. Ang II actions on blood pressure regulation, water electrolyte balance, and hormone secretion are primarily mediated by AGTR1. The function of AGTR2 remains unclear. Here, we show that expression of the AGTR2 gene was absent in a female patient with mental retardation (MR) who had a balanced X;7 chromosomal translocation. Additionally, 8 of 590 unrelated male patients with MR were found to have sequence changes in the AGTR2 gene, including one frameshift and three missense mutations. These findings indicate a role for AGTR2 in brain development and cognitive function.

Amino Acid Sequence↗
PubMed2002

Evaluation of solid dispersions of Clofazimine.

Clofazimine (CLF) was formulated with polyethylene glycol (PEG) and polyvinyl pyrrolidone (PVP) as a solid solid dispersion (SSD) to increase the aqueous solubility and dissolution rate of the drug. Different molecular weights of PEG (1500, 4000, 6000, and 9000 Da) and PVP (14,000 and 44,000 Da) were used in different drug:carrier weight ratios (1:1, 1:5, and 1:9) and their effect on the dissolution performance of the drug was evaluated in USP Type 2 apparatus using 0.1 N HCl medium. The dissolution rate was compared with corresponding physical mixtures, a currently marketed soft gelatin capsule product, and free CLF. The effect of different methods of preparation (solvent/melt) on the dissolution rate of CLF was evaluated for PEG solid dispersions. Saturation solubility and phase solubility studies were carried out to indicate drug:carrier interactions in liquid state. Infrared (IR) spectroscopy and X-ray diffraction (XRD) were used to indicate drug:carrier interactions in solid state. Improvement in the drug dissolution rate was observed in solid dispersion formulations as compared to the physical mixtures. The dissolution rate improved with the decreasing weight fraction of the drug in the formulation. Polyvinyl pyrrolidone solid dispersion systems gave a better drug release profile as compared to the corresponding PEG solid dispersions. The effect of molecular weight of the PEG polymers did not follow a definite trend, while PVP 14,000 gave a better dissolution profile as compared to PVP 44,000. Improvement in saturation solubility of the drug in the solid dispersion systems was noted in all cases. Further, IR spectroscopy indicated drug:carrier interactions in solid state in one case and XRD indicated reduction in the crystallinity of CLF in another. It was concluded that solid-dispersion formulations of Clofazimine can be used to design a solid dosage form of the drug, which would have significant advantages over the currently marketed soft gelatin capsule dosage form.

Anti-Inflammatory Agents, Non-Steroidal↗