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Biomedical subjects

S Bharati

Publications and source records attributed to S Bharati.

At least 19 recordsLinked to original sources
PubMed2006

Body mass index and chronic energy deficiency of adult males of Central Indian populations.

Data on body weight, height, and sitting height from 11,496 adult males, age 18-62 years, belonging to 38 different populations of five major social groups (scheduled tribes, scheduled castes, "other backward castes," general castes, and Muslims) of Central India were taken for our analysis to assess the nutritional status of these groups. Cormic index and body mass index (BMI) were computed, and an analysis of variance (ANOVA) was carried out among different populations as well as among social groups separately on Cormic index and BMI. Shape, size, and generalized distances among the different social groups were computed and dendrograms were drawn. The level of malnutrition is the lowest among the general castes. The opposite is the case with the scheduled castes and scheduled tribes. Comparison of the coefficient of variation shows that there is variation in weight and BMI but that there is no marked variation in the other anthropometric variables. The ANOVA on Cormic index and BMI suggests that the people within a population are more homogeneous than the people between populations. There is a positive but statistically insignificant correlation between Cormic index and BMI. The five social groups differ more in size distance than in shape distance. According to the dendrogram of generalized distance values, the Muslims and the general castes can be grouped into one cluster and the scheduled castes, scheduled tribes, and other backward castes can be grouped into another cluster.

Adolescent↗
PubMed2004

Patterns of ethnic, linguistic, and geographic heterogeneity of palmar interdigital ridge counts in the Indian subcontinent.

Published data on palmar interdigital ridge counts (a-b, b-c, and c-d) among 57 populations from the Indian subcontinent were analyzed with reference to ethnic, socioeconomic, linguistic, and geographic affiliations of the studied populations. The spatial autocorrelation analysis suggests significant correlation between dermatoglyphic and geographic distances. The congruence with the ethnic semblance of the groups is also apparent in the data, and, in fact, the multiresponse permutation procedure did suggest highly significant within-group homogeneity, confirming the biological validity of the social and ethnic criteria used in the analysis. The plots of populations on the first two principal components, accounting for 92% of the total variance, complement and support the results based on the other analyses, which show certain ethnic and geographic patterns. These findings can serve as baseline information for future studies on population variation in India, particularly studies based on molecular genetic markers, a trend that has already gained momentum.

Dermatoglyphics↗
PubMed2002

Pattern of adolescent growth among the Brahmin girls--rural-urban variation.

A cross-sectional study of adolescent growth was undertaken among the Brahmin girls residing in rural and urban areas of Sagar districts, Madhya Pradesh to evaluate the urban-rural differences. Six anthropometric measurements, such as weight, stature, sitting height, head circumference, upper arm circumference and chest girth are taken into consideration. Though the urban girls show consistently higher values of weight, stature, sitting height and chest girth than the rural girls, but in case of head circumference and upper arm circumference they show consistently lower values. The maximum increment occurs between the ages 13 and 14 years in all the six measurements in both rural and urban girls.

Adolescent↗
PubMed2001

His electrogram alternans reveal dual-wavefront inputs into and longitudinal dissociation within the bundle of His.

BACKGROUND: His electrogram (HE) amplitude and morphology changes were observed in our previous studies during transition from "fast" to "slow" atrioventricular nodal (AVN) conduction. This phenomenon and its significance for the dual-AVN electrophysiology are not well recognized and have not been studied. METHODS AND RESULTS: Experiments were performed on 17 healthy rabbit atrial-AVN preparations during standard programmed electrical pacing. HEs were mapped along the His bundle with roving surface electrodes, along with recording of cellular action potentials (APs). HEs recorded from the superior margin of the His bundle were of greater amplitude during basic beats and decreased substantially, by 42+/-19% (P<0.01), when premature A(1)A(2) shortened to 178+/-20 ms. In contrast, the HEs from the inferior margin increased dramatically, 2.9+/-1.7 times (P<0.01), during short A(1)A(2) and remained high until AVN block occurred. In addition, during long A(1)A(2), the superior HEs consistently preceded the inferior by 1.9+/-0.7 ms. In contrast, at short A(1)A(2), the superior HEs occurred 2.7+/-0.8 ms after the inferior. Cellular AP recordings demonstrated clearly the presence of and the transition between early (fast) and late (slow) excitation wavefronts that accompanied HE alternans. CONCLUSIONS: The morphological-electrophysiological evidence from the AV junction suggests that fast and slow wavefronts reach the His bundle differently, producing functional longitudinal dissociation into 2 domains. The characteristic HE alternans recorded from these domains are a new sensitive tool to determine the presence of distinctly different wavefronts and their participation in the conduction during reentrant or other arrhythmias. These findings provide further understanding of the mechanisms of dual-AVN electrophysiology.

Action Potentials↗
PubMed2001

The ablation of atrial fibrillation with the loop catheter design: what we have learned from the animal model.

Ablation of chronic atrial fibrillation (AF) with the use of transcutaneous catheter ablation is yet to become a clinical tool. This article summarizes the development of the technology and the technique for the ablation of AF that was tested on the rapidly paced AF dog model. The current ablation technology using the standard ablation technique used in humans is not suitable for the creation of transmural contiguous linear lesions, and such technology is subjecting the patient to the prolonged procedures with considerable risk of complication. The use of the loop catheter design or other designs of ablation technology, which is specifically targeted for the creation of linear lesions, should be developed if the catheter approach for the ablation of AF is to succeed. This article describes the data available for the loop catheter design that is currently undergoing human feasibility studies.

Animals↗
PubMed2000

Repair of chromosomal abasic sites in vivo involves at least three different repair pathways.

We introduced multiple abasic sites (AP sites) in the chromosome of repair-deficient mutants of Escherichia coli, in vivo, by expressing engineered variants of uracil-DNA glycosylase that remove either thymine or cytosine. After introduction of AP sites, deficiencies in base excision repair (BER) or recombination were associated with strongly enhanced cytotoxicity and elevated mutation frequencies, selected as base substitutions giving rifampicin resistance. In these strains, increased fractions of transversions and untargeted mutations were observed. In a recA mutant, deficient in both recombination and translesion DNA synthesis (TLS), multiple AP sites resulted in rapid cell death. Preferential incorporation of dAMP opposite a chromosomal AP site ('A rule') required UmuC. Furthermore, we observed an 'A rule-like' pattern of spontaneous mutations that was also UmuC dependent. The mutation patterns indicate that UmuC is involved in untargeted mutations as well. In a UmuC-deficient background, a preference for dGMP was observed. Spontaneous mutation spectra were generally strongly dependent upon the repair background. In conclusion, BER, recombination and TLS all contribute to the handling of chromosomal AP sites in E.coli in vivo.

Amino Acid Substitution↗
PubMed2000

Accessory atrioventricular node with properties of a typical accessory pathway: anatomic-electrophysiologic correlation.

We report an accessory AV node producing ventricular preexcitation and comprising the retrograde limb of AV reentrant tachycardia (AVRT). A 66-year-old man presented with an anteroseptal myocardial infarction and thereafter developed recurrent, drug-refractory AVRT requiring multiple cardioversions. Electrophysiologic findings were typical for a concealed anteroseptal accessory pathway 0.5 cm anterior to the His bundle. The patient died of intractable heart failure after endocardial resection for a left ventricular aneurysm and coronary bypass grafting. Pathologic examination revealed a para-Hisian accessory AV node connecting the right atrium to ventricular myocardium immediately anterior to the His bundle at a depth of 4 mm from the endocardium. No typical AV accessory pathway was found. This is the first report of an accessory AV node that participated in AVRT. It was deeper than typical radiofrequency catheter ablation lesions.

Aged↗
PubMed1999

Living anatomy of the atrioventricular junctions. A guide to electrophysiologic mapping. A Consensus Statement from the Cardiac Nomenclature Study Group, Working Group of Arrhythmias, European Society of Cardiology, and the Task Force on Cardiac Nomenclature from NASPE.

Current nomenclature for the atrioventricular (AV) junctions derives from a surgically distorted view, placing the valvar rings and the triangle of Koch in a single plane with antero-posterior and right-left lateral coordinates. Within this convention, the aorta is considered to occupy an anterior position, although the mouth of the coronary sinus is shown as being posterior. Although this nomenclature has served its purpose for the description and treatment of arrhythmias dependent on accessory pathways and atrioventricular nodal reentry, it is less than satisfactory for the description of atrial and ventricular mapping. To correct these deficiencies, a consensus document has been prepared by experts from the Working Group of Arrhythmias of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology. It proposes a new anatomically sound nomenclature that will be applicable to all chambers of the heart. In this report, we discuss its value for description of the AV junctions, establishing the principles of this new nomenclature.

Atrioventricular Node↗
PubMed1999

Living anatomy of the atrioventricular junctions. A guide to electrophysiological mapping. A Consensus Statement from the Cardiac Nomenclature Study Group, Working Group of Arrythmias, European Society of Cardiology, and the Task Force on Cardiac Nomenclature from NASPE. North American Society of Pacing and Electrophysiology.

Current nomenclature for atrioventricular junctions derives from a surgically distorted view, placing the valvar rings and the triangle of Koch in a single plane with antero-posterior and right-left lateral coordinates. Within this convention, the aorta is considered to occupy an anterior position, while the mouth of the coronary sinus is shown as being posterior. While this nomenclature has served its purpose for the description and treatment of arrhythmias dependent on accessory pathways and atrioventricular nodal re-entry, it is less than satisfactory for the description of atrial and ventricular mapping. To correct these deficiencies, a consensus document has been prepared by experts from the Working Group of Arrhythmias of the European Society of Cardiology, and the North American Society of Pacing and Electrophysiology. It proposes a new, anatomically sound, nomenclature that will be applicable to all chambers of the heart. In this report, we discuss its value as regards the description of the atrioventricular junctions, establishing the principles of this new nomenclature.

Atrioventricular Node↗
PubMed1999

ESCWGA/NASPE/P experts consensus statement: living anatomy of the atrioventricular junctions. A guide to electrophysiologic mapping. Working Group of Arrhythmias of the European Society of Cardiology. North American Society of Pacing and Electrophysiology.

Current nomenclature for the AV junctions derives from a surgically distorted view, placing the valvar rings and the triangle of Koch in a single plane with anteroposterior and right-left lateral coordinates. Within this convention, the aorta is considered to occupy an anterior position, whereas the mouth of the coronary sinus is shown as being posterior. Although this nomenclature has served its purpose for the description and treatment of arrhythmias dependent on accessory pathways and AV nodal reentry, it is less than satisfactory for the description of atrial and ventricular mapping. To correct these deficiencies, a consensus document has been prepared by experts from the Working Group of Arrhythmias of the European Society of Cardiology and from the North American Society of Pacing and Electrophysiology. It proposes a new, anatomically sound, nomenclature that will be applicable to all chambers of the heart. In this report, we discuss its value for description of the AV junctions and establish the principles of this new nomenclature.

Atrioventricular Node↗
PubMed1998

Human mitochondrial uracil-DNA glycosylase preform (UNG1) is processed to two forms one of which is resistant to inhibition by AP sites.

The preform of human mitochondrial uracil-DNA glycosylase (UNG1) contains 35 N-terminal residues required for mitochondrial targeting. We have examined processing of human UNG1 expressed in insect cells and processing in vitro by human mitochondrial extracts . In insect cells we detected a major processed form lacking 29 of the 35 unique N-terminal residues (UNG1Delta29, 31 kDa) and two minor forms lacking the 75 and 77 N-terminal residues, respectively (UNG1Delta75 and UNG1Delta77, 26 kDa). Purified UNG1Delta29 was effectively cleaved in vitro to a fully active 26 kDa form by human mitochondrial extracts. Furthermore, endogenous forms of 31 and 26 kDa were also observed in HeLa mitochondrial extracts. The sequences at the cleavage sites, as identified by peptide sequencing, were compatible with the known specificity of mitochondrial processing peptidase (MPP). However, in vitro cleavage of UNG1Delta29 by mitochondrial extracts did not require divalent cations and was stimulated by EDTA, indicating the involvement of a processing peptidase distinct from MPP at the second site. Interestingly, while UNG1Delta29 generally has the typical properties reported for other uracil-DNA glycosylases, it is not inhibited by apurinic/apyrimidinic sites. Our results indicate that the preform of human mitochondrial uracil-DNA glycosylase is processed to distinctly different forms lacking 29 or 75/77 N-terminal residues, respectively.

Amino Acid Sequence↗
PubMed1998

Base excision repair initiation revealed by crystal structures and binding kinetics of human uracil-DNA glycosylase with DNA.

Three high-resolution crystal structures of DNA complexes with wild-type and mutant human uracil-DNA glycosylase (UDG), coupled kinetic characterizations and comparisons with the refined unbound UDG structure help resolve fundamental issues in the initiation of DNA base excision repair (BER): damage detection, nucleotide flipping versus extrahelical nucleotide capture, avoidance of apurinic/apyrimidinic (AP) site toxicity and coupling of damage-specific and damage-general BER steps. Structural and kinetic results suggest that UDG binds, kinks and compresses the DNA backbone with a 'Ser-Pro pinch' and scans the minor groove for damage. Concerted shifts in UDG simultaneously form the catalytically competent active site and induce further compression and kinking of the double-stranded DNA backbone only at uracil and AP sites, where these nucleotides can flip at the phosphate-sugar junction into a complementary specificity pocket. Unexpectedly, UDG binds to AP sites more tightly and more rapidly than to uracil-containing DNA, and thus may protect cells sterically from AP site toxicity. Furthermore, AP-endonuclease, which catalyzes the first damage-general step of BER, enhances UDG activity, most likely by inducing UDG release via shared minor groove contacts and flipped AP site binding. Thus, AP site binding may couple damage-specific and damage-general steps of BER without requiring direct protein-protein interactions.

Amino Acid Sequence↗
PubMed1998

An experimental model of sudden death due to low-energy chest-wall impact (commotio cordis)

BACKGROUND: The syndrome of sudden death due to low-energy trauma to the chest wall (commotio cordis) has been described in young sports participants, but the mechanism is unknown. METHODS: We developed a swine model of commotio cordis in which a low-energy impact to the chest wall was produced by a wooden object the size and weight of a regulation baseball. This projectile was thrust at a velocity of 30 miles per hour and was timed to the cardiac cycle. RESULTS: We first studied 18 young pigs, 6 subjected to multiple chest impacts and 12 to single impacts. Of the 10 impacts occurring within the window from 30 to 15 msec before the peak of the T wave on the electrocardiogram, 9 produced ventricular fibrillation. Ventricular fibrillation was not produced by impacts at any other time during the cardiac cycle. Of the 10 impacts sustained during the QRS complex, 4 resulted in transient complete heart block. We also studied whether the use of safety baseballs, which are softer than standard ones, would reduce the risk of arrhythmia. A total of 48 additional animals sustained up to three impacts during the T-wave window of vulnerability to ventricular fibrillation with a regulation baseball and safety baseballs of three degrees of hardness. We found that the likelihood of ventricular fibrillation was proportional to the hardness of the ball, with the softest balls associated with the lowest risk (two instances of ventricular fibrillation after 26 impacts, as compared with eight instances after 23 impacts with regulation baseballs). CONCLUSIONS: This experimental model of commotio cordis closely resembles the clinical profile of this catastrophic event. Whether ventricular fibrillation occurred depended on the precise timing of the impact. Safety baseballs, as compared with regulation balls, may reduce the risk of commotio cordis.

Animals↗
PubMed1998

Relationship between menarcheal age and nutritional anthropometry in urban girls of the Howrah District, West Bengal, India.

The present paper deals with the menarche and nutritional anthropometry among Bengali girls aged 9 to 16 years (n = 645) living in the city of Howrah (West Bengal, India). The result show that within the same socioeconomic group early menarche girls were heavier and taller than the late menarche girls. There is a significant difference between not attained menarche (NAM) and attained menarche (AM) girls aged 12 and 13 years for height and for 12 to 14 years in case of weight.

Adolescent↗
PubMed1997

A sequence in the N-terminal region of human uracil-DNA glycosylase with homology to XPA interacts with the C-terminal part of the 34-kDa subunit of replication protein A.

Uracil-DNA glycosylase releases free uracil from DNA and initiates base excision repair for removal of this potentially mutagenic DNA lesion. Using the yeast two-hybrid system, human uracil-DNA glycosylase encoded by the UNG gene (UNG) was found to interact with the C-terminal part of the 34-kDa subunit of replication protein A (RPA2). No interaction with RPA4 (a homolog of RPA2), RPA1, or RPA3 was observed. A sandwich enzyme-linked immunosorbent assay with trimeric RPA and the two-hybrid system both demonstrated that the interaction depends on a region in UNG localized between amino acids 28 and 79 in the open reading frame. In this part of UNG a 23-amino acid sequence has a significant homology to the RPA2-binding region of XPA, a protein involved in damage recognition in nucleotide excision repair. Trimeric RPA did not enhance the activity of UNG in vitro on single- or double-stranded DNA. A part of the N-terminal region of UNG corresponding in size to the complete presequence was efficiently removed by proteinase K, leaving the proteinase K-resistant compact catalytic domain intact and fully active. These results indicate that the N-terminal part constitutes a separate structural domain required for RPA binding and suggest a possible function for RPA in base excision repair.

Amino Acid Sequence↗
PubMed1997

Prominent venous valves in hypoplastic right hearts.

To investigate the hypothesis that embryologic abnormalities in the venous valves may be associated with abnormal cardiac development, we examined the right atrial morphologic characteristics in 20 hearts with underdevelopment of the right heart and 17 normal hearts. In the study group, 16 (80%) of the patients had significantly enlarged eustachian valves, one (5%) was slightly enlarged, and three (15%) were smaller than expected. Five (25%) had cor triatriatum dexter. In comparison, eustachian valves in the control specimens were prominent in only one (6%), normal in five (29%), and almost absent in eight (47%). The thebesian valve was also more prominent in the study cohort when compared with controls (p < 0.05). No other morphologic features of the right atrium analyzed in this study differed from those found in normal specimens. We speculate that failure of the venous valves to regress appropriately may create abnormalities in fetal circulation that predispose the fetus to maldevelopment of the right heart structures.

Adult↗
PubMed1997

Complete AV block following mediastinal radiation therapy: electrocardiographic and pathologic correlation and review of the world literature.

The clinical, features, serial electrocardiograms, and autopsy findings of a patient with symptomatic complete AV block, who had received mediastinal radiation therapy 8 1/2 years previously, are presented. The cardiac histopathology disclosed immense fibrosis of the conduction system and of the atria and ventricles. The enormous amount of fibrosis was similar in location and intensity to that observed in our previously reported patient (Cohen et al., Arch Intern Med 1981; 141:676-679) who had undergone mediastinal radiation. We conclude that the severe fibrosis was primarily due to radiation, rather than secondary to atherosclerotic coronary artery disease, which also has been described as a consequence of mediastinal radiotherapy. This patient's serial electrocardiograms disclosed evidence of complete block both in the AV nodal area and infra His system, which correlated well with the histopathology. The characteristic clinical features of patients with symptomatic complete AV block post mediastinal radiation therapy are presented, along with a review of the world literature.

Adult↗