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Biomedical subjects

K Taneja

Publications and source records attributed to K Taneja.

At least 19 recordsLinked to original sources
PubMed1997

Ductus arteriosus aneurysm in the adult: role of computed tomography in diagnosis.

Aneurysm of the ductus arteriosus has been reported in children more frequently than in adults [1-4]. The rarity of the lesion explains the low rate of recognition by the radiologist, especially because symptoms are non-specific in most cases. Clinically and radiologically, aneurysm of the ductal diverticulum can be confused with other mass lesions in the aorticopulmonary window. We report CT features of two ductal aneurysm in the adult with atypical presentation.

Adult↗
PubMed1997

Nuclear domains of the RNA subunit of RNase P.

The ribonucleoprotein enzyme RNase P catalyzes the 5' processing of pre-transfer RNA, and has also recently been implicated in pre-ribosomal RNA processing. In the present investigation, in situ hybridization revealed that RNase P RNA is present throughout the nucleus of mammalian cells. However, rhodamine-labeled human RNase P RNA microinjected into the nucleus of rat kidney (NRK) epithelial cells or human (HeLa) cells initially localized in nucleoli, and subsequently became more evenly distributed throughout the nucleus, similar to the steadystate distribution of endogenous RNase P RNA. Parallel microinjection and immunocytochemical experiments revealed that initially nucleus-microinjected RNase P RNA localized specifically in the dense fibrillar component of the nucleolus, the site of pre-rRNA processing. A mutant RNase P RNA lacking the To antigen binding domain (nucleotides 25-75) did not localize in nucleoli after nuclear microinjection. In contrast, a truncated RNase P RNA containing the To binding domain but lacking nucleotides 89-341 became rapidly localized in nucleoli following nuclear microinjection. However, unlike the full-length RNase P RNA, this 3' truncated RNA remained stably associated with the nucleoli and did not translocate to the nucleoplasm. These results suggest a nucleolar phase in the maturation, ribonucleoprotein assembly or function of RNase P RNA, mediated at least in part by the nucleolar To antigen. These and other recent findings raise the intriguing possibility of a bifunctional role of RNase P in the nucleus: catalyzing pre-ribosomal RNA processing in the nucleolus and pre-transfer RNA processing in the nucleoplasm.

Animals↗
PubMed1996

Occlusive arterial disease of the upper extremity: colour Doppler as a screening technique and for assessment of distal circulation.

A prospective study was performed to evaluate the sensitivity of colour Doppler flow imaging (CDFI) in the detection of occlusive arterial disease in the upper limb (using angiography as the standard) and to quantify the severity of the disease. Twenty-one ischaemic and 15 healthy limbs were studied by intra-arterial digital subtraction angiograms (IADSA) and CDFI. Selective subclavian digital subtraction angiograms were performed by the percutaneous transfemoral route. CDFI was performed from the brachial artery superiorly to the subclavian artery origin. Special attention was paid to the study of spectral waveforms and peak systolic velocities at various levels. In each subject, IADSA and CDFI were performed by different radiologists without knowledge of the results of the other investigation. In normal limbs, all arteries demonstrated a characteristic sharp triphasic spectral pattern with mean peak systolic velocity of 105, 80 and 57 cm/s for the subclavian, axillary and brachial arteries, respectively. In ischaemic limbs, reduction in peak systolic value and broadening of the spectral trace with filling in of the spectral window were noted. More characteristic was the finding of a loss of diastolic flow reversal, which was the earliest sign of significant arterial stenosis. The pattern of diastolic blood flow correlated well with the degree of collateral formation and distal vascular runoff. In conclusion, CDFI has a high sensitivity and specificity in the detection of significant arterial stenosis and is thus an ideal, inexpensive screening procedure. Analysis of the diastolic wave-form distal to the stenosis is an indicator of the degree of collateral circulation and distal runoff and thus acts as a prognostic indicator, guiding further investigation and management.

Angiography, Digital Subtraction↗
PubMed1996

Morphologic mural changes in the aorta revealed by CT in patients with nonspecific aortoarteritis (Takayasu's arteritis).

OBJECTIVE: Nonspecific aortoarteritis is a panarteritis of unknown cause that primarily involves vessel walls. The imaging morphology of changes caused by nonspecific aortoarteritis has been infrequently studied. SUBJECTS AND METHODS: We analyzed this morphology by axial CT in 24 patients (group 1) and compared these images with those of healthy subjects (n = 12, group 2) and subjects with atherosclerosis (n = 12, group 3), aortic aneurysm (n = 9, group 4), and aortic dissection (n = 5, group 5). Ten-millimeter contiguous sections were obtained before and after enhancement with contrast material. RESULTS: Distinctive wall changes were seen in group 1 and included thickening in 20 patients, crescents in 19, indistinct outline in 10, and low-attenuation ring in eight. Calcification and thrombus were seen in 13 and seven patients, respectively. Angiograms showed skip areas of involvement. CT scans showed wall changes even in skipped areas that were normal at angiography. In group 2, the aortic wall was imperceptible or less than 1 mm thick and showed no abnormality. In group 3, calcification was seen in all patients and wall abnormality in none. In group 4, changes, including thrombus in all patients, calcification in nine, and low-attenuation ring in one patient, were seen within the aneurysm. In group 5, changes included calcification and the intimal flap in all patients and thrombus in three. CONCLUSION: CT shows distinctive changes in the aortic wall in patients with non-specific aortoarteritis that are peculiar to this disease. Detecting these changes may improve our understanding of the disease pathogenesis. Our findings suggest that this disease involves a contiguous length of the aorta, producing wall and luminal diameter changes in some areas and only wall changes in the intervening segments.

Adolescent↗
PubMed1995

Systemic-to-pulmonary artery collateral vessels and surgical shunts in patients with cyanotic congenital heart disease: perioperative treatment by transcatheter embolization.

OBJECTIVE: Systemic-to-pulmonary collateral vessels can develop in patients with obstruction of the right ventricular outflow tract or the pulmonary artery. Occlusion of these vessels is necessary before surgical correction of the primary disease. We report the results of transcatheter coil embolization in the treatment of 56 patients. MATERIALS AND METHODS: Seventy-four procedures were done in the perioperative period for treatment of 67 aortopulmonary collateral arteries, five modified Blalock-Taussig shunts, and two enlarged veins. RESULTS: In the "aortopulmonary collateral" group, occlusion was complete in 51 patients (76%), subtotal in seven (10%), partial in four (6%), and failed in five (8%). Inadvertent embolization to the aorta occurred in two procedures, but both coils were retrieved nonsurgically. During follow-up of 1-12 months (n = 32; mean, 6.3 months), the coils remained in position, without any migration. Follow-up angiograms in 14 embolized vessels showed no recanalization (mean, 5.3 months; range, 2-12 months). In the "shunt" group, occlusion was complete in four patients and failed in one. Distal embolization to the pulmonary artery occurred in one patient. This coil was retrieved during surgery. During follow-up of 3-6 months, coils remained in position in all patients. In one patient, a follow-up angiogram at 3 months showed no recanalization. In the "venous embolization" group, occlusion was complete in one patient. The coils were in position 5 months later. The procedure was unsuccessful in the other patient. CONCLUSION: We conclude that transcatheter coil embolization is useful in the treatment of abnormal systemic-to-pulmonary vessels and shunts in patients with obstruction of the right ventricular outflow tract or the pulmonary artery. Homemade coils are safe and effective in obliterating antegrade flow.

Adolescent↗
PubMed1992

Acute osteomyelitis: early diagnosis by ultrasonography.

A prospective study was carried out to evaluate the role of ultrasound in early detection of infections of bone. Presence of a hypoechoic collection adjacent to bone was considered highly suggestive of osteomyelitis whereas a hypoechoic collection away from the bone implied a soft tissue abscess. Cellulitis presented as increased subcutaneous thickness. Of the 31 patients clinically suspected to have osteomyelitis, and subjected to ultrasound, 25 were proven to be osteomyelitis at surgery or by subsequent radiological changes, 4 had soft tissue abscesses and the remaining 2 had cellulitis. Co-existent hip joint effusion was seen in 2 patients. It is felt that ultrasound is simple and non-invasive investigation, capable of detecting bone and soft tissue infections.

Acute Disease↗
PubMed1990

Sonography of hip joint in infective arthritis.

The most important determinant of outcome of a hip infection is the delay between the onset of the infection and treatment. Transient synovitis, and septic and tubercular arthritis of the hip remain common diagnostic problems. Conventional radiographic examinations are of little help in early diagnosis. Computed tomography, scintigraphy and magnetic resonance imaging, though informative, are expensive and not universally available. Ultrasonography (US) of the hip was done in 50 patients to define sonographic anatomy, detect joint effusions and correlate sonographic features with the etiology of the disease. Even small collections of fluid could be detected with accuracy. Both hypo- and hyperechoic synovial fluid was seen in septic arthritis, but hyperechoicity and a thickened capsule were the most characteristic findings. Synovial fluid had mixed echogenicity in tubercular and transient synovitis. The use of other (invasive) imaging modalities can be minimized because US can be used not only to demonstrate effusions early in the disease but also the status of the intra-articular compartment, joint capsule, bony surface and adjacent soft tissues. Ultrasonography should be used more commonly to diagnose infective arthritis, and no patient should be subjected to arthrotomy or drainage if US has ruled out the presence of a fluid collection.

Adolescent↗
PubMed1989

Temporal resolution and sequential expression of muscle-specific genes revealed by in situ hybridization.

The expression of muscle-specific mRNAs was analyzed directly within individual cells by in situ hybridization to chicken skeletal myoblasts undergoing differentiation in vitro. The probes detected mRNAs for sarcomeric myosin heavy chain (MHC) or the skeletal, cardiac, and beta isoforms of actin. Precise information as to the expression of these genes in individual cells was obtained and correlated directly with analyses of cell morphology and interactions, cell cycle stage, and immunofluorescence detection of the corresponding proteins. Results demonstrate that mRNAs for the two major muscle-specific proteins, myosin and actin, are not synchronously activated at the time of cell fusion. The mRNA for alpha-cardiac actin (CAct), known to be the predominant embryonic actin isoform in muscle, is expressed prior to cell fusion and prior to the expression of any isoform of muscle MHC mRNA. MHC mRNA accumulates rapidly immediately after fusion, whereas skeletal actin mRNA is expressed only in larger myofibers. Single cells expressing CAct mRNA have a characteristic short bipolar morphology, are in terminal G1, and do not contain detectable levels of the corresponding protein. In a pattern of expression reciprocal to that of CAct mRNA, beta-actin mRNA diminishes to low or undetectable levels in myofibers and in cells of the morphotype which expresses CAct mRNA. Finally, the intracellular distribution of mRNAs for different actin isoforms was compared using nonisotopic detection of isoform-specific oligonucleotide probes. This work illustrates a generally valuable approach to the analysis of cell differentiation and gene expression which directly integrates molecular, morphological, biochemical, and cell cycle information on individual cells.

Actins↗
PubMed1989

Scurvy--the eternal masquerader.

Osseous involvement in scurvy is unusual in older children even though classical bony changes are well recognized in the infantile variety. This report describes two children with scurvy, aged 6 and 8 years, both of whom presented with bone pains and associated swelling. One child also had a pathological telescoping diaphyseal fracture--a complication not previously described in association with scurvy.

Child↗
PubMed1987

Use of oligodeoxynucleotide probes for quantitative in situ hybridization to actin mRNA.

We have employed an analytical approach for the development of an in situ hybridization methodology using synthetic oligodeoxynucleotide probes for actin messenger RNA detection in cultures of chicken fibroblasts and myoblasts. The methodology developed shows that oligonucleotides can complement the use of nick-translated probes in specific situations. Since they can be made to specific nucleic acid regions independent of restriction enzyme sites, they may be the most convenient approach for analysis of gene families among which sequences are highly conserved. However, it was found that oligonucleotides synthesized to different regions of a messenger RNA behave in situ with differing efficiencies, indicating that not all target sequences are equivalent. Therefore it was necessary to screen several oligonucleotide probes to a target molecule to find the optimal one. The convenience of using synthetic DNA probes makes it worthwhile to explore some of these characteristic properties so as to increase the sensitivity of this approach beyond its application to targets in high abundance.

Actins↗
PubMed1987

Molecular biology of the HLA system in insulin-dependent diabetes mellitus.

Genetic studies indicate that the IDDM susceptibility genes in the HLA region are closely linked to the DR3 and DR4 specificities; however, these specificities do not define the actual susceptibility genes. Molecular studies confirm this hypothesis by demonstrating restriction fragment length polymorphism between DNA's of identical DR specificities and thereby separating the DR haplotypes into those strongly or weakly associated with IDDM. Further studies at the nucleotide sequence level demonstrate further heterogeneity, with DR4 being associated with at least three different DQ beta genes and five different genes of the DR beta-1 locus. However, the majority of these subtypes are now recognized either serologically or by T-cell responses in mixed lymphocyte cultures. Furthermore, the sequences associated with IDDM are those most commonly found in DR4 individuals, ie, Dw4 and DQw3.2. Clearly, these and other class II genes must be studied for additional DNA polymorphism and their relevance for IDDM. For example, the DX alpha, 2.1-kb Taql polymorphism shows a stronger correlation with IDDM than DR3. However, it is not even known if the DX alpha genes are expressed. In addition, little is known of the DQ beta and DR beta genes associated with different DR3-associated haplotypes. Furthermore, an IDDM susceptibility gene may contain important differences in flanking or intron sequences controlling expression of these genes. The methods of recombinant DNA technology are enabling these unanswered questions to be addressed.

Base Sequence↗