PubMed Health⌕ Search

Biomedical subjects

S S Prasad

Publications and source records attributed to S S Prasad.

At least 19 recordsLinked to original sources
PubMed2006

Pyle's disease: an incidental finding in a routine dental patient.

Pyle's disease (PD) or metaphyseal dysplasia is an extremely rare genetic disorder, transmitted as an autosomal recessive trait. The peculiarity of the disease is that the striking radiographic manifestations contrast with the relatively normal clinical features. The oral findings and radiographic features of the disease are not well documented. The present paper describes the radiographic features of Pyle's disease in a 17-year-old girl and draws attention to the findings in the jaw bones.

Adolescent↗
PubMed2005

Postnatal expression profile of OBCAM implies its involvement in visual cortex development and plasticity.

This study examined the expression of a neuron-specific cell adhesion molecule, OBCAM (opioid-binding cell adhesion molecule), at both the mRNA and protein levels in the cat primary visual cortex at various postnatal ages, using cDNA array analysis and immunocytochemistry. Results obtained using both methods showed that the expression level of OBCAM was high in young and low in older and adult visual cortex. OBCAM-immunoreactivities were associated predominantly with perikarya and dendrites of pyramidal neurons, and OBCAM-immunopositive neurons were present in all cortical layers. Immunostaining of OBCAM in adult visual cortex showed a reduced number of immunopositive neurons and neurites and relatively lower staining intensities as compared with younger animals. In addition, the number of OBCAM-immunopositive neurons was significantly higher in the visual cortex of 4-month-old animals dark-reared from birth than those in age-matched normally reared animals. These results suggest that OBCAM may play an important role in visual cortex development and plasticity.

Aging↗
PubMed2004

Management of subtrochanteric femoral fractures and metastases using long proximal femoral nail.

We report our initial experience with a new reconstruction nail, the long proximal femoral nail (L.PFN), in the treatment of subtrochanteric femoral fractures and metastases. We performed 52 L.PFN in 49 patients over a period of 18 months with an average follow-up period of 47.7 weeks. Group I consisted of 24 patients, who had L.PFN for traumatic subtrochanteric femoral fractures. Group II consisted of 25 patients, who had L.PFN for femoral metastases and pathological fractures. (Three bilateral.) In nine patients in group I, the fracture was extending to the intertrochnateric region with involvement of the piriformis fossa. Eight patients in group I had open reduction and cerclage cabling of the fracture prior to L.PFN. All the traumatic fractures in group I had united with an average time to union of 19.4 weeks. In eight operations there were technical difficulties with the insertion of proximal locking screws. Five patients in our series had complications but we had no mechanical failures of the implant. L.PFN is a reliable implant for subtrochanteric femoral fractures and metastases. We also showed that open reduction and cerclage cabling of unstable subtrochanteric fractures prior to nailing was not detrimental to fracture healing in our series.

Adult↗
PubMed2003

A case report of a spinal epidural haematoma associated with warfarin therapy.

Spinal epidural haematoma is an uncommon, but recognised, clinical entity that needs emergency management. The association of spinal epidural haematomata with warfarin therapy has been described and, in 1956, Alderman stated that this diagnosis should be entertained in any patient receiving anticoagulants presenting with low back pain or sciatic pain. The purpose of this case report is to increase the awareness of this entity among medical personnel and to stress the urgency of management.

Anticoagulants↗
PubMed2003

Hemangioblastoma: a study of radiopathologic correlation.

Computerized tomography (CT) scan and operative observations, and histolopathogical findings of 25 cases of intracranial hemangioblastoma were correlated. Solid hemangioblastomas showed a large number of thin-walled capillaries and abundant stromal cells with eosinophilic cytoplasm. Tumors with a cystic component and a mural nodule had a large number of stromal cells with vacuolated cytoplasm and microcysts.

Adolescent↗
PubMed2002

Immunohistochemical investigations of neurofilament M' and alphabeta-crystallin in the magnocellular layers of the primate lateral geniculate nucleus.

The magnocellular and parvocellular pathways are two major processing streams in the primate visual system. Using high-density grid arrayed cDNA clones to hybridize to cDNA probes from cortical regions of each pathway, a list of candidate differentially expressed genes was produced [Mol. Brain Res. 82 (2000) 11-24]. Magnocellular pathway candidates include neurofilament M' and alphabeta-crystallin. Using antibodies generated against these proteins, immunohistochemical analysis revealed preferential staining of the magnocellular layers in the primate lateral geniculate nucleus, providing verification of two candidate magnocellular-enriched genes.

Animals↗
PubMed2002

Gene expression patterns during enhanced periods of visual cortex plasticity.

During a critical period in its postnatal development the mammalian visual cortex displays susceptibility to experience-dependent alterations of neuronal response properties. Plasticity represents an integrated set of developmental processes controlled by a transcriptional hierarchy that coordinates the action of many genes. To illuminate the expression of these critical genes, we examined gene expression patterns of 18371 non-redundant cDNAs in the visual cortex of cats at birth, at eye opening, at the peak of the critical period of eye dominance plasticity and in the adult cat using filter-based cDNA arrays and software-based hierarchical cluster analysis. We identified a small set of genes that were selectively expressed during the peak of the critical period for plasticity. We further examined the patterns of expression of these genes by analyzing the gene expression pattern of dark-reared chronologically older animals that are known to retain this ocular dominance plasticity beyond the chronologically defined critical period. This additional cluster assessment allowed us to separate age-related changes in the patterns of gene expression from plasticity-related changes, thus identifying a subset of genes that we define as plasticity candidate genes. Those plasticity candidate genes that have previously characterized functions include participants in second messenger systems, in cell adhesion, in transmitter recycling and cytokines, among others. Comparison of cDNA array quantitation with reverse transcription-polymerase chain reaction showed almost identical expression profiles for three genes that we examined. The expression pattern of one identified gene, opioid binding cell adhesion molecule, from the cDNA array analysis, is also in agreement with immunocytochemical results. We conclude that the approach of high-density cDNA array hybridization can be used as a useful tool for examining a complex phenomenon of developmental plasticity since it is amenable to multiple developmental stage gene expression comparisons.

Animals↗
PubMed2001

Identification of a novel truncated isoform of trkB in the kitten primary visual cortex.

Neurotrophins have been shown to play important roles in development and plasticity of the visual cortex (VC). Since signal transduction of neurotrophins is mediated through neurotrophin receptors, we attempted to analyze neurotrophin receptors in the VC. In this study, we isolated cDNAs encoding the intracellular regions of truncated isoforms of the trkB receptor from 30-d-old kitten primary VC. Two distinct truncated isoforms of trkB were isolated and characterized by sequence analyses. One of the isoforms corresponds to the previously described truncated trkB in several mammalian species. The second isoform represents a novel truncated trkB variant form in the kitten VC. Sequence analysis revealed that this contains a sequence that has not yet been reported in any species. This novel isoform, designated trkB.T4, results from alternative splicing 189-bp (63 amino acids) downstream from the splice site giving rise to the first known truncated isoforms of trkB. In the context of recent hypotheses regarding the function of truncated trkB receptors, sequence analysis indicates that trkB.T4 may bear putative signaling/internalization sequences.

Amino Acid Sequence↗
PubMed2000

Identification of differentially expressed genes in the visual structures of brain using high-density cDNA grids.

The hybridization patterns of 18,371 high-density-grid-arrayed non-redundant complementary DNA (cDNA) clones were examined using three different sources of cDNA probes. The first set of probes was synthesized from mRNA isolated from visual brain areas MT and V4 of Vervet monkey. The second set of probes was derived from cDNA libraries constructed from two micro dissected sets of layers of the monkey Lateral Geniculate Nucleus layers within the visual pathway, namely the magnocellular and parvocellular layers. The third set of cDNA probes was synthesized from the subtracted fractions of the cDNAs enriched for either the magnocellular or the parvocellular layers of the Lateral Geniculate Nucleus. Software, linked directly to the Genbank database, was developed to aid in the rapid identification of both expressed and differentially expressed genes. Our results indicate that both the cDNA probes synthesized from mRNA and cDNA libraries can identify similar fractions of expressed genes. However, the subtracted cDNA probes improve the efficiency of detection for those genes that are expressed at much lower abundance. Analyses of these results for the differential expression patterns of these genes were validated by semi-quantitative PCR on the DNA derived from the whole tissue cDNA libraries. A list of some known genes that are statistically differentially expressed within the magnocellular layers of the LGN and area MT in the primate visual areas is derived.

Animals↗
PubMed1994

Identification of cDNA clones expressed selectively during the critical period for visual cortex development by subtractive hybridization.

We have used the method of subtractive hybridization to isolate cDNA clones of mRNAs expressed in abundance in the visual cortex of 30-day-old kittens but absent or in lower abundance in the adult cat visual cortex. Of 12,000 colonies screened, 200 clones which hybridized to the subtracted probe were isolated and characterized. Northern blots confirmed the specificity of the vast majority of the isolated clones. 120 of the 200 clones were sequenced and the EMBL and GenBank (release 76) database were searched for known identities using FASTA and BLAST programs. Twenty-seven of these sequenced clones were identifiable. The identities showed that these sequences code for proteins involved in a variety of cellular processes. These include cell-cell interaction (TAPA-1, contactin, tachykinin receptor, phospholipase A2), cellular remodeling (C1q beta isoform, heat shock protein), neurofilament assembly (alpha tubulin and alpha internexin), neurotransmitter release (VAMP-2, amphiphysin, carboxypeptidase E, scg 10 and proton channel), energy metabolism (mitochondrial hinge protein, ADP/ATP transporter, cytochrome oxidase subunits), RNA processing (helix destabilizing protein, ribonucleoprotein) and protein synthesis (eIF-4A initiation factor, ribosomal protein S27). The results show that gene expression in the kitten visual cortex differs rather little from that of the adult visual cortex since over 98% of the sequences appear common. The relatively rare kitten-specific sequences are likely to form the basis for the critical period plasticity in this system.

Aging↗
PubMed1993

Molecular analysis of two genes between let-653 and let-56 in the unc-22(IV) region of Caenorhabditis elegans.

A previous study of genomic organization described the identification of nine potential coding regions in 150 kb of genomic DNA from the unc-22(IV) region of Caenorhabditis elegans. In this study, we focus on the genomic organization of a small interval of 0.1 map unit bordered on the right by unc-22 and on the left by the left-hand breakpoints of the deficiencies sDf9, sDf19 and sDf65. This small interval at present contains a single mutagenically defined locus, the essential gene let-56. The cosmid C11F2 has previously been used to rescue let-56. Therefore, at least some of C11F2 must reside in the interval. In this paper, we report the characterization of two coding elements that reside on C11F2. Analysis of nucleotide sequence data obtained from cDNAs and cosmid subclones revealed that one of the coding elements closely resembles aromatic amino acid decarboxylases from several species. The other of these coding elements was found to closely resemble a human growth factor activatable Na+/H+ antiporter. Paris of oligonucleotide primers, predicted from both coding elements, have been used in PCR experiments to position these coding elements between the left breakpoint of sDf19 and the left breakpoint of sDf65, between the essential genes let-653 and let-56.

Amino Acid Sequence↗
PubMed1993

Molecular characterization in the dpy-14 region identifies the adenosylhomocysteine hydrolase gene in Caenorhabditis elegans.

The region around dpy-14 on chromosome 1 of Caenorhabditis elegans has been extensively studied genetically, with regard to essential gene organization. This region was one of the first for which cloned DNA was available as a result of restriction fragment length polymorphism mapping. To examine the information content of the cloned DNA in this region, evolutionarily conserved sequences were identified by cross-species hybridization. Ten regions of conservation have been identified and characterized with regard to mRNA abundance and DNA sequence. cDNAs were obtained for seven of these conserved regions and sequence from the cDNAs were used to search the SWISS protein and EMBL nucleotide data banks. Two coding regions shared DNA identifies with existing sequences, the opa repeat family of Drosophila and the S-adenosylhomocysteine hydrolase gene. Of the three for which no corresponding cDNA were found, one corresponds to the snRNA U1-1. The other two did not detect transcripts on Northern analysis and are either conserved, but not coding, or code for low abundance transcripts. The density of conserved coding regions in this study was one per 15 kbp of genomic DNA, three times lower than that reported on chromosome 3 by the genome sequencing project.

Adenosylhomocysteinase↗
PubMed1991

Evolutionarily conserved regions in Caenorhabditis transposable elements deduced by sequence comparison.

In this paper we present the sequence of an intact Caenorhabditis briggsae transposable element, Tcb2. Tcb2 is 1606 base pairs in length and contains 80 base pair imperfect terminal repeats and a single open reading frame. We have identified blocks of T-rich repeats in the regions 150-200 and 1421-1476 of this element which are conserved in the Caenorhabditis elegans element Tc1. The sequence conservation of these regions in elements from different Caenorhabditis species suggests that they are of functional importance. A single open reading frame corresponding to the major open reading frame of Tc1 is conserved among Tc1, Tcb1, and Tcb2. Comparison of the first 550 nucleotides of the sequence among the three elements has allowed the evaluation of a model proposing an extension of the major open reading frame. Our data support the suggestion that Tc1 is capable of producing a 335 amino acid protein. A comparison of the sequence coding for the amino and carboxy termini of the 273 amino acid transposase from Caenorhabditis Tc1-like elements and Drosophila HB1 showed different amounts of divergence for each of these regions, indicating that the two functional domains have undergone different amounts of selection. Our data are not compatible with the proposal that Tc1-related sequences have been acquired via horizontal transmission. The divergence of Tc1 from the two C. briggsae elements, Tcb1 and Tcb2, indicated that all three elements have been diverging from each other for approximately the same amount of time as the genomes of the two species.

Amino Acid Sequence↗
PubMed1989

Evolutionarily conserved coding sequences in the dpy-20-unc-22 region of Caenorhabditis elegans.

Caenorhabditis elegans provides an excellent opportunity to study the organization of a complex genome. The alignment of the genetic and molecular maps over a large stretch of the genome is an essential part of this study. The objective of this paper was the identification and characterization of coding regions in four cosmids containing DNA from the interval between dpy-20 and unc-22 on linkage group IV. These cosmids were characterized with regard to the map position and the developmental patterns of expression of coding sequences. Since an extensive genetic map already exists for this region, this detailed description of the coding sequences in the dpy-20-unc-22 region will make possible alignment of the molecular and genetic maps for this portion of the C. elegans genome. In this study, we have used interspecies cross-hybridization to localize and identify potential coding elements. We have investigated four cosmids containing approximately 150 kb of C. elegans genome adjacent to the well-characterized muscle gene, unc-22(IV). Fragments subcloned from the four cosmids were hybridized at moderate stringency to the genome of the related species, Caenorhabditis briggsae. In this way nine potential coding regions were identified. Seven of these nine fragments also hybridized to mRNA transcripts on Northern blots. Five of the seven showed maximal hybridization to RNA from L2-stage animals, a pattern that resembles that of actin transcription. It is speculated that the functions of these five may in some way be related to one another, and perhaps also to that of unc-22, which is itself a muscle gene.

Animals↗
PubMed1980

Reduced motor conduction velocity of the ulnar nerve in spinal cord injured patients.

Twelve male patients with spinal cord injury were studied. The purpose of this study was to determine if ulnar nerve damage occurs in patients with spinal cord injury who are wheelchair bound and if so at which segment of the ulnar nerve. The results showed significant drop in ulnar nerve conduction velocity in both segments, mid-arm to below elbow and below to the wrist. There was no significant difference between quadriplegic and paraplegic. No significant correlation was found between ulnar nerve impairment and the duration of spinal cord injury.

Adult↗