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Biomedical subjects

Rajesh Sharma

Publications and source records attributed to Rajesh Sharma.

At least 19 recordsLinked to original sources
PubMed2006

Subcutaneous emphysema secondary to pulmonary cavity in absence of pneumothorax or pneumomediastinum.

Subcutaneous emphysema is a common condition occurring after chest injury. It may also be observed in association with pneumothorax or pneumomediastinum as a result of pathological changes in the respiratory tract. Spontaneous subcutaneous emphysema in absence of pneumothorax or pneumomediastinum is rare. We report a case of spontaneous subcutaneous emphysema in isolation secondary to fibrocavitatory lesion in the chest along with review of the literature.

Eyelids↗
PubMed2006

Structural evaluation of radially expandable cardiovascular stents encased in a polyurethane film.

A method of encasing cardiovascular stents with an expandable polyurethane coating has been developed to provide a smooth homogeneous inner wall allowing for a confluent growth of endothelial cells. In this design, the metal wire stent structure is completely covered by the polyurethane film, minimizing biocorrosion of the metal (stainless steel or nitinol), and providing a homogeneous surface for surface treatment and incorporation of various eluting drugs to prevent platelet aggregation while supporting endothelialization. The polyurethane surface was treated with a helium plasma for sterilization and promotes growth of cells. The article details the performance of the coated film to expand with the metal stent up to 225% during deployment. Stress/strain behavior of polyurethane films, subsequent plasma treatment of the surface, and the adhesion of the coating to the stent structure upon expansion are presented. A film of less than 25 microm was found to be sufficient for corrosion resistance and flexibility without producing any excess stress on the stent structure. Straining the film to 225% and plasma modification did not affect the mechanical and surface properties, but allowed for improved biocompatibility as determined by the critical surface tension, surface chemistry, and roughness.

Arteries↗
PubMed2006

Total anomalous pulmonary venous connection with intact interatrial septum.

The presence of an interatrial communication is considered an integral part of the diagnosis of total anomalous pulmonary venous connection and is believed to be essential for survival. We report a 9-month-old infant with obstructed supracardiac total anomalous pulmonary venous connection without an interatrial communication.

Cardiac Surgical Procedures↗
PubMed2004

Replication-mediated instability of the GAA triplet repeat mutation in Friedreich ataxia.

Friedreich ataxia is caused by the expansion of a polymorphic and unstable GAA triplet repeat in the FRDA gene, but the mechanisms for its instability are poorly understood. Replication of (GAA*TTC)n sequences (9-105 triplets) in plasmids propagated in Escherichia coli displayed length- and orientation-dependent instability. There were small length variations upon replication in both orientations, but large contractions were frequently observed when GAA was the lagging strand template. DNA replication was also significantly slower in this orientation. To evaluate the physiological relevance of our findings, we analyzed peripheral leukocytes from human subjects carrying repeats of similar length (8-107 triplets). Analysis of 9400 somatic FRDA molecules using small-pool PCR revealed a similar mutational spectrum, including large contractions. The threshold length for the initiation of somatic instability in vivo was between 40 and 44 triplets, corresponding to the length of a eukaryotic Okazaki fragment. Consistent with the stabilization of premutation alleles during germline transmission, we also found that instability of somatic cells in vivo and repeats propagated in E.coli were abrogated by (GAGGAA)n hexanucleotide interruptions. Our data demonstrate that the GAA triplet repeat mutation in Friedreich ataxia is destabilized, frequently undergoing large contractions, during DNA replication.

DNA↗
PubMed2004

Friedreich ataxia in carriers of unstable borderline GAA triplet-repeat alleles.

Friedreich ataxia patients are homozygous for expanded GAA triplet-repeats containing 66 to 1,700 triplets. We report two patients with delayed-onset, hyperreflexia and gradually progressive disease. Both were heterozygous for large expansions and also carried alleles with 44 and 66 triplet-repeats, respectively. Due to somatic instability, 15% (GAA-44) and 75% (GAA-66) of cells contained alleles with >/=66 triplet-repeats, constituting a plausible mechanism for their mild phenotype. A sibling with a stable GAA-37 allele and a large expansion was clinically normal. Instability of borderline alleles confers a risk for Friedreich ataxia, and the range of pathogenic alleles is broader than previously recognized.

Alleles↗
PubMed2004

Postoperative assessment of the univentricular repair by dynamic radionuclide studies.

BACKGROUND: The purpose of this investigation was to determine the role of radionuclide studies in evaluating postoperative Fontan hemodynamics and to quantify its diagnostic accuracy. METHODS: One hundred five patients (105), aged 11 months to 35 years old, who had undergone univentricular repair, underwent first-pass and multigated acquisition scan 1 month to 10 years after univentricular repair. Forty-five patients with evidence of Fontan failure underwent radionuclide studies using Technetium-99 m as well as cardiac catheterization (group 1). The remaining sixty randomly selected patients with excellent functional status received radionuclide studies alone (group 2). The receiver operating characteristic curve analysis was done to quantify the diagnostic accuracy of the first-pass study. RESULTS: There was paradoxical filling of the right lung after femoral injection in all cases of tunnel or conduit obstruction. A first-pass transit time of 16 to 25 seconds (mean +/- standard deviation [SD] = 18.82 +/- 2.69) was always associated with Fontan failure and high right atrial pressure (range = 20 to 24 mm Hg, mean +/- SD = 22.02 +/- 1.58). A first-pass transit time of 16 seconds was associated with a sensitivity of 100% and a specificity of 93.33%. The predictive accuracy of a positive or negative result was 91.8% and 100% respectively. The area measured under the receiver operating characteristic curve indicates that 99.41% (SE +/- 0.0035) of the time, the value of first-pass time is higher for the Fontan failure group (group 1) compared to the normal group (group 2; p = 0.000). CONCLUSIONS: Our data indicate that Fontan circuit can be reliably evaluated for both anatomic and functional flaws by radionuclide studies; radionuclide first-pass time may be used to predict the chances of Fontan failure postoperatively as well as its presence; and in the presence of atrial fibrillation with fast ventricular rate, analysis using first-pass radionuclide may be impossible and gated equilibrium radionuclide angiocardiography may be the preferred method. Inspection of the systemic ventricular time-activity curve is of crucial importance in this regard.

Adolescent↗
PubMed2004

Genetic admixture of European FRDA genes is the cause of Friedreich ataxia in the Mexican population.

Friedreich ataxia accounts for approximately 75% of European recessive ataxia patients. Approximately 98% of pathogenic chromosomes have large expansions of a GAA triplet repeat in the FRDA gene (E alleles), and strong linkage disequilibrium among polymorphisms spanning the FRDA locus indicates a common origin for all European E alleles. In contrast, we found that only 14 of 151 (9.3%) Mexican Mestizo patients with recessive ataxia were homozygous for E alleles. Analysis of polymorphisms spanning the FRDA locus revealed that all Mestizo E alleles had the common European haplotype, indicating that they share a single origin. Genetic admixture levels were determined, which revealed that the relative contributions to the Mestizo FRDA gene pool by Native American and European genes were 76-87% and 13-24%, respectively, commensurate with the observed low prevalence of Friedreich ataxia in Mestizos. This indicates that Friedreich ataxia in Mexican Mestizos is due to genetic admixture of European mutant FRDA genes in the Native American gene pool that existed prior to contact with Europeans.

Adaptor Proteins, Signal Transducing↗
PubMed2004

Immunogenicity of low dose intradermal hepatitis B vaccine and its comparison with standard dose intramuscular vaccination.

OBJECTIVE: A prospective study was carried out in the well baby and immunization clinics of tertiary care hospital to compare the immunogenicity of low dose hepatitis B vaccine (HBV) given intradermally versus standard dose given intramuscularly. METHODS: One hundred ninety six term, healthy, Australia antigen negative and exclusively breast fed babies were allocated into two groups in a simple randomized manner. In group I, hepatitis B vaccine was given in low dose (2 mcg) by intradermal route whereas in group II it was administered in standard dose (10 mcg) by intramuscular route. Diphtheria, pertussis, tetanus (DPT) and oral polio vaccine (OPV) were co-administered with HBV in both the groups at 6, 10 and 14 weeks of age at different sites. One hundred seventy seven infants could be regularly followed up and tested for anti-HBs titres by third generation ELISA test using mono-ELISA anti-HBs 3.0 kits. Geometric mean titres of anti-HBs were estimated in each group and compared. Student's t-test was used for statistical analysis. RESULTS: Seroprotective anti-HBs titres (titre greater than 10 mIU/mL) were achieved in 87 of 88 (98.8 percent) children having received intramuscular doses as compared to 82 of 89 (92.1 percent) children in the intradermal group. The geometric mean titres of the intradermal group were 92.71 mIU/mL (95 percent C.I. 68.85-124.85), significantly lower than 331.66 mIU/mL (95 percent C.I. 245.12-448.78), noticed in the intramuscular group. There were no significant adverse reactions in both the groups. Hepatitis B vaccine is immunogenic when co-administered with DPT and OPV vaccine. The intradermal hepatitis B administration is less effective with lower immunogenicity than the intramuscular vaccination.

Antibody Formation↗
PubMed2003

Genetic counseling and prenatal diagnosis in India--experience at Sir Ganga Ram Hospital.

UNLABELLED: The experiences in genetic counseling and prenatal diagnosis at a tertiary genetic center in India are described. Of 3500 subjects provided genetic counseling 28.7% were for prenatal diagnosis, 13.7% for mental retardation +/- malformations, 11.5% for thalassemia, hemophilia and leukemia, 8.5% for neural tube defects and other malformations, and 8% for muscle dystrophy and spinal muscle atrophy. Chromosomal studies in blood (n = 5459) were for recurrent abortions (57.8%), delayed milestones (14.7%), malformations (11%), and infertility and amenorrhea (10.2%). Indications for amniotic fluid studies (n = 835) were advanced maternal age (35.7%), high risk result on triple test (21.3%), previous child with trisomy 21 (21.3%) and abnormalities seen on ultrasound (11.1%). Molecular studies were mostly for thalassemia (843, 24.3%), Duchenne muscular dystrophy (443, 12.5%), fragile X syndrome (367, 10.3%), spinal muscular atrophy (315, 8.9%), thrombophilia profile (233, 6.6%), triplet repeat disorders-spinocerebellar ataxias, Huntington disease and Friedreich ataxia-162 (4.6%), cystic fibrosis 140 (3.9%) and mitochondrial disorders 101 (2.9%). Other disorders for which molecular diagnosis was done were intrauterine infections by PCR on the amniotic fluid, Prader Willi/Angelman syndromes, hemophilia, achondroplasia, congenital adrenal hyperplasia, and Apert syndrome etc. In biochemical studies triple marker tests were the most common (3239), followed by aminoacid chromatography (774). Among neurolipidosis metachromatic leukodystrophy was the commonest, followed by Krabbe's disease, Tay Sach disease and Gaucher disease. Of the mucopolysacharidoses Hurler syndrome was the commonest, followed by Hunter syndrome. These data are compared with previous studies and a change towards increased prenatal diagnostic tests is observed. The commonest indication for amniocentesis has changed to advanced maternal age. CONCLUSION: Advanced molecular, cytogenetic and biochemical techniques have been a useful addition for genetic counseling and prenatal diagnosis in India.

Chromosome Aberrations↗
PubMed2003

Modified circuit for retrograde cerebral perfusion.

A modified circuit for delivery of retrograde cerebral perfusion during ascending aortic or aortic arch surgery is described. The technique was applied in 15 patients who showed good postoperative recovery.

Aortic Dissection↗
PubMed2002

The GAA triplet-repeat sequence in Friedreich ataxia shows a high level of somatic instability in vivo, with a significant predilection for large contractions.

Friedreich ataxia is commonly caused by large expansions of a GAA triplet-repeat (GAA-TR) sequence in the first intron of the FRDA gene. We used small-pool PCR to analyze somatic variability among 7190 individual FRDA molecules from peripheral blood DNA of subjects carrying 12 different expanded alleles, ranging in size from 241 to 1105 triplets. Expanded alleles showed a length-dependent increase in somatic variability, with mutation loads ranging from 47% to 78%. We noted a strong contraction bias among long alleles (>500 triplets), which showed a 4-fold higher frequency of large contractions versus expansions. Some contractions were very large; of all somatic mutations scored, approximately 5% involved contractions of >50% of the original allele length, and 0.29% involved complete reversion to the normal/premutation length (< or =60 triplets). These observations contrast sharply with the strong expansion bias seen in expanded CTG triplet repeats in myotonic dystrophy. No somatic variability was detected in >6000 individual FRDA molecules analyzed from 15 normal alleles (8-25 triplets). A premutation allele with 44 uninterrupted GAA repeats was found to be unstable, ranging in size from 6 to 113 triplets, thus establishing the threshold for somatic instability between 26 and 44 GAA triplets. Analysis of an additional 7850 FRDA molecules from serially passaged lymphoblastoid cell lines carrying nine expanded alleles (132-933 triplets) showed very low mutation loads, ranging from 0% to 6.2%. Our data indicate that expanded GAA-TR alleles in Friedreich ataxia are highly mutable and have a natural tendency to contract in vivo, and that these properties depend on multiple factors, including DNA sequence, triplet-repeat length and unknown cell-type-specific factors.

DNA↗
PubMed2002

Left ventricle is better suited as pulmonary ventricle in simple transposition with severe pulmonary hypertension.

BACKGROUND: The conventional treatment of transposition of great arteries with prepared left ventricle is an arterial switch operation. This, in our experience, does not hold for patients with transposition of great arteries with intact ventricular septum where the left ventricle continues to be prepared secondary to severe pulmonary arterial hypertension without an immediately reversible cause. METHODS: Ten infants with D-transposition of the great arteries with essentially intact interventricular septum and severe pulmonary arterial hypertension underwent surgical treatment. Age ranged from 3 to 6 months (mean, 4.2 months). One of these patients had a large ductus with left to right shunting but the others had no intra- or extracardiac shunt to account for their pulmonary hypertension. All 10 had "prepared" left ventricles. The first 4 children underwent an arterial switch operation. Uneventful surgery was followed by prolonged ventilator dependence in all 4 with occurrence of severe pulmonary arterial hypertension every time weaning from ventilator was attempted. This was accompanied by metabolic acidosis and features of right heart failure. Only 1 patient with large ductus could be extubated and discharged from hospital. Subsequently, the other 6 infants underwent a Senning repair. RESULTS: There was no early mortality. All patients were separated from mechanical ventilation within 48 hours of surgery without blood gas derangement or heart failure despite elevated pulmonary artery pressure in all. The child with the arterial switch operation has pulmonary artery pressure of 50% systemic 4 years following repair; although among the Senning group, 2 patients continue to have pulmonary artery pressure more than 60% of systemic and 4 have normal pulmonary artery pressure at a mean follow-up of 1 year. CONCLUSIONS: Atrial level repairs seem to perform better than arterial level repairs in children having TGA with persistent pulmonary artery hypertension without a correctable cause. Better tolerance of pulmonary arterial hypertension in this group is probably consequent to the superior ability of the left ventricle to tolerate a pressure load in the early postoperative period.

Ductus Arteriosus, Patent↗
PubMed2002

Can late survival of patients with moderate ischemic mitral regurgitation be impacted by intervention on the valve?

BACKGROUND: Ischemic mitral regurgitation is known to be associated with poor long-term outcome after coronary artery bypass grafting; however, our ability to alter that outcome with intervention on the valve is unclear. The decision to address the valve is most challenging for patients with only moderate mitral regurgitation, particularly with the popularization of off-pump surgery. We therefore reviewed early and late outcomes of patients undergoing revascularization with or without mitral valve surgery. METHODS: Patients with moderate mitral regurgitation undergoing revascularization with and without mitral surgery between January 1991 and September 1996 were identified retrospectively. Operative notes were reviewed and patients with structural valve disease excluded. Perioperative events and late outcomes as determined by telephone contact and search of the social security death index (survival data 97% complete) were compared. RESULTS: One hundred seventy-six patients with moderate mitral regurgitation underwent revascularization alone (n = 142) or with mitral repair or replacement (n = 34). Those undergoing revascularization alone had a higher serum creatinine, somewhat less mitral regurgitation, and lower New York Heart Association functional class preoperatively. Operative mortality was greater with valve surgery (21% vs 9%, p = 0.047). Actuarial survival of both groups at 5 years was similar (52% vs 58%, p = NS); however, when stratified by preoperative functional class, those with more advanced heart failure preoperatively had superior late survival if their mitral valve was intervened upon. CONCLUSIONS: The late survival of patients with ischemic mitral regurgitation undergoing coronary revascularization remains poor; however, intervention on the mitral valve appears to benefit those with symptomatic heart failure.

Adult↗
PubMed2002

Late outcome after arterial switch operation for complete transposition of great arteries with left ventricular outflow tract obstruction.

BACKGROUND: Long-term follow-up of patients who underwent arterial switch operation for complete transposition of great arteries with anatomic left ventricular outflow tract obstruction (LVOTO) has rarely been brought into the focus. METHODS: Of 299 patients who underwent an arterial switch operation between January 1991 and January 2001, 23 patients had anatomic LVOTO. Age ranged from 4 days to 18 years (median 90 days) and weight ranged from 2.6 to 35 kg (median 4.3 kg). Surgical management included arterial switch operation, closure of ventricular septal defect wherever indicated, and excision of LVOTO. RESULTS: Among patients with preoperative LVOTO there were 2 early deaths and 8 patients had mild neoaortic regurgitation at the time of discharge. Follow-up ranged from 8 months to 9 years (mean 60 +/- 12 months). In 4 patients who had mild neoaortic regurgitation at discharge, the regurgitation progressed to moderate or severe degree after a follow-up of 22 to 72 months. In 1 patient mild mitral regurgitation present at the time of discharge progressed to severe mitral regurgitation. This patient subsequently underwent double valve replacement. CONCLUSIONS: Presence of preoperative anatomical LVOTO in patients undergoing arterial switch operation predicts high incidence of postoperative neoaortic regurgitation.

Adolescent↗
PubMedDate not supplied

Redo mitral valve surgery-a long-term experience.

BACKGROUND: Our experience with reoperative mitral valve (MV) surgery over a 27-year period is presented here. METHODS: From January 1975 to June 2002, 11,908 operations were performed for MV disease. Out of these 744 were reoperations. The mean age at primary operation was 23.6 +/- 10.1 years (range 2 to 53 years) and at reoperation was 36.0 +/- 11.0 years (range 6 to 65 years) with a mean interval of 11.5 +/- 2.5 years. Mitral valve replacement (MVR) was performed following previous closed mitral valvotomy (CMV) in 408 patients, open mitral commissurotomy (OMC) in 21 patients, and MV repair in 58 patients, MVR in 80 patients, homograft mitral valve replacement (HMVR) in 11 patients. The reasons for reoperation were mainly progression of lesions. Valve thrombosis and endocarditis were indications for reoperation following MVR. Twenty-eight patients underwent redo CMV, 53 patients underwent OMC, and 14 patients underwent MV Repair. RESULTS: Early mortality was 5.64% (n = 42). Hemorrhage and low cardiac output were the major causes. Follow-up was 124.8 +/- 30.5 months (2 to 300 months). Follow-up was 88%. There were no late deaths in the valve repair group. There were three episodes of thromboembolism in this group (0.3% per patient-year). In the valve replacement group there were six late deaths; three due to valve thrombosis, one due to infective endocarditis, and two due to anticoagulant-related hemorrhage. There were 13 episodes of thromboembolism in this group (0.6% per patient-year). CONCLUSION: Redo MV surgery is safe and can be undertaken with acceptable mortality and morbidity.

Adolescent↗