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Biomedical subjects

K Taneja

Publications and source records attributed to K Taneja.

At least 19 recordsLinked to original sources
PubMed2001

Replication timing of human telomeric DNA and other repetitive sequences analyzed by fluorescence in situ hybridization and flow cytometry.

The replication timing of telomeres seems to differ between species. Yeast telomeres are late replicating, whereas limited data from very few human cell lines have indicated telomere replication throughout S phase. In the present study a series of permanent cell lines and patient samples was investigated using a flow cytometric approach for telomere length determination based on in situ hybridization using peptide nucleic acid probes and DNA staining. This method permits selective analysis of cells in specific phases of the cell cycle without perturbation of the cell cycle machinery. The timing of replication of telomeric C(3)TA(2) and T(2)AG(3) repeats was found to differ between individual samples and could precede or be concomitant with the replication of bulk DNA. Replication of the T(2)AG(3) strand seemed to occur somewhat later than that of the C(3)TA(2) strand in some samples. (GTG)(n) and other repetitive sequences generally showed a replication pattern similar to that of the bulk of DNA with slightly individual differences, whereas centromeric DNA repeats consistently replicated within a short time frame in late S phase. The apparent variability in replication timing seen for telomeric DNA might suggest individual differences in firing of replication origins.

Cell Cycle↗
PubMed2001

Defective satellite cells in congenital myotonic dystrophy.

In this study we have developed an in vitro cell culture system which displays the majority of the defects previously described for congenital myotonic dystrophy (CDM) muscle in vivo. Human satellite cells were isolated from the quadriceps muscles of three CDM fetuses with different clinical severity. By Southern blot analysis all three cultures were found to have approximately 2300 CTG repeats. This CTG expansion was found to progressively increase in size during the proliferative life span, confirming an instability of this triplet in skeletal muscle cells. The CDM myoblasts and myotubes also showed abnormal retention of mutant RNA in nuclear foci, as well as modifications in their myogenic program. The proliferative capacity of the CDM myoblasts was reduced and a delay in fusion, differentiation and maturation was observed in the CDM cultures compared with unaffected myoblast cultures. The clinical severity and delayed maturation observed in the CDM fetuses were closely reflected by the phenotypic modifications observed in vitro. Since the culture conditions were the same, this suggests that the defects we have described are intrinsic to the program expressed by the myoblasts in the absence of any trophic factors. Altogether, our results demonstrate that satellite cells are defective in CDM and are probably implicated in the delay in maturation and muscle atrophy that has been described previously in CDM fetuses.

Biopsy↗
PubMed2001

Decreased levels of myotonic dystrophy protein kinase (DMPK) and delayed differentiation in human myotonic dystrophy myoblasts.

Muscle cell cultures derived from a myotonic dystrophy (DM1) fetus were established in order to determine on the one hand, whether the differentiation of DM1 myoblasts is altered and, on the other hand, whether the levels of myotonic dystrophy protein kinase (DMPK) protein is decreased in DM1 muscle cells. DM1 myoblasts isolated from a quadriceps of a 12-weeks old fetus proliferate at a similar rate as normal myoblasts isolated from a quadriceps of an unaffected 15-weeks old fetus but their maturation is altered as shown by the decreased levels in slow myosin heavy chain protein. In contrast, no change was observed in the expression of vimentin, myogenin and embryonic myosin heavy chain. The levels of DMPK transcripts sharply increased during myoblast differentiation and the mutant DMPK transcripts are retained in discrete foci in the nuclei of muscle cells. The levels of 85-kDa DMPK protein was reduced by about 50% in DM1 cells compared with normal cells. Our study demonstrates that delay in DM1 myoblast maturation is associated with nuclear retention of mutant DMPK transcripts and decreased levels of DMPK protein.

Antibodies, Monoclonal↗
PubMed1999

Amiodarone-induced pulmonary toxicity in an adolescent.

We report amiodarone-induced pulmonary toxicity in an 18-year-old boy who had undergone corrective surgery for tetralogy of Fallot 4 years earlier, and was treated with amiodarone because of recurrent malignant postoperative ventricular tachyarrhythmias. Toxicity was recognized on the basis of clinical features, chest X-ray, high-resolution contrast enhanced computerized tomography, and resolution of the findings subsequent to withdrawal of amiodarone and treatment with steroids. Pulmonary toxicity due to amiodarone, as far as we know, has not been reported in children and young adults, and its occurence even in young adults requires wider appreciation.

Adolescent↗
PubMed1998

Congenital H-type urethroanal fistula.

A case of congenital urethroanal fistula with a normal anterior urethra in a male child is reported. The fistula was demonstrated between the prostatic urethra and anorectum. This anomaly is usually associated with an atretic anterior urethra and has been variously described as a variant of a urethral duplication by some authors, and of an anorectal malformation (ARM) by others. We conclude that its rightful classification is as a variant of ARM in which the fistula is a result of persistence of the cloacal duct and corresponds to the anorecto-vestibular fistula with a normal anus (perineal canal) in a female.

Humans↗
PubMed1998

Morphological mural changes in the aorta in non-specific aortoarteritis (Takayasu's arteritis): assessment by intravascular ultrasound imaging.

OBJECTIVE: Non-specific aortoarteritis (Takayasu's arteritis) is a panarteritis of unknown aetiology which primarily involves the vessel walls. The imaging morphology of wall abnormalities has been infrequently studied and their intravascular ultrasound appearance is not reported in the literature. METHOD: We studied this morphology by intravascular ultrasound in nine patients in whom the diagnosis of Takayasu's arteritis was made by clinical and angiographic criteria. Intravascular ultrasound was performed by the transfemoral route. Images of the aorta were obtained in each patient. Qualitative and quantitative analysis was performed. RESULTS: All procedures were successful, without complication. Typical findings included thickening and altered echogenicity of the media, adventitia and peri-arterial tissues. The inner echogenic layer was thin. Pliability of aortic walls was lost in stenotic segments. Aortic calcification was seen in one patient. The aortic wall thickness was 0.17-0.58 cm. Angiograms showed skip areas of aortic involvement. Intravascular ultrasound showed wall changes even in the skip areas which were normal at angiography. CONCLUSION: Intravascular ultrasound shows changes in the aortic wall morphology in non-specific aortoarteritis. Our findings suggest that this disease involves contiguous aortic segments, producing wall and luminal changes in some areas and only wall changes in intervening areas.

Adolescent↗
PubMed1998

Recurrent pseudoaneurysm of the left ventricle with subcutaneous herniation into the chest wall. A case report.

Pseudoaneurysm of the left ventricle is rare, and recurrence is extremely rare. We report the case of a 62-year-old man who presented at our hospital with a painless pulsatile swelling in the left breast. He had undergone coronary artery bypass grafting and left-ventricular aneurysmectomy 14 years earlier. On investigation, the swelling was diagnosed to be a pseudoaneurysm of the left ventricle with subcutaneous herniation. The extreme rarity of this condition prompted us to report the case. The investigative techniques and the surgical strategy are discussed.

Aneurysm, False↗
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↗