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Biomedical subjects

R Chandra

Publications and source records attributed to R Chandra.

At least 55 records · Page 3Linked to original sources
PubMed1998

Nasal sill augmentation in adult incomplete cleft lip nose deformity using superiorly based turn over orbicularis oris muscle flap: an anatomic approach.

Adult incomplete cleft lip nose deformity is not uncommon in India. Poverty, ignorance, and parental neglect account for its late presentation. Besides the classical features of cleft lip nose deformity, the constant findings observed in this patient population have been a widened and depressed nasal sill. This is attributable to the sparse, hypoplastic, and abnormally orientated orbicularis oris muscle in the region of the sill. Failure to restore the nasal sill symmetry by suitably augmenting the sill frequently leads to unsatisfactory and asymmetric results. However, in the literature, satisfactory restoration of the nasal sill has not been given the importance it deserves while performing cleft lip rhinoplasty. We present a method of augmenting the depressed nasal sill in cases of adult incomplete nose deformity using a superiorly based orbicularis oris muscle flap, which is harvested from the soft tissues between the apex of the cleft and the nostril sill. Following de-epithelialization of the overlying skin, the exposed muscle is raised as a superiorly based flap after dissecting it from the underlying mucosa. It is folded, turned over, and tucked into the nasal sill base and anchored to the anterior nasal spine to give the desired augmentation. Satisfactory results have been obtained in 18 cases of nasal deformity associated with incomplete cleft lip. In our opinion, this technique offers a simple and effective method of augmenting the depressed sill by utilizing locally available tissues and without the need for procuring autologous tissue from distant sites.

Adolescent↗
PubMed1998

Multiple effects of KPQ deletion mutation on gating of human cardiac Na+ channels expressed in mammalian cells.

Several aspects of the effect of the KPQ deletion mutation on Na+ channel gating remain unresolved. We have analyzed the kinetics of the early and late currents by recording whole cell and single-channel currents in a human embryonic kidney (HEK) cell line (HEK293) expressing wild-type and KPQ deletion mutation in cardiac Na+ channels. The rate of inactivation increased three- to fivefold between -40 and -80 mV in the mutant channel. The rate of recovery from inactivation was increased twofold. Two modes of gating accounted for the late current: 1) isolated brief openings with open times that were weakly voltage dependent and the same as the initial transient and 2) bursts of opening with highly voltage-dependent prolonged open times. Latency to first opening was accelerated, suggesting an acceleration of the rate of activation. The delta KPQ mutation has multiple effects on activation and inactivation. The aggregate effects may account for the increased susceptibility to arrhythmias.

Animals↗
PubMed1998

Transplacental transfer of measles antibody in Delhi.

OBJECTIVE: To find out the patterns of and the factors, if any, affecting the transplacental transfer of measles antibody. DESIGN: Comparison of measles antibody titres in mothers with titres in cord blood samples. METHODS: Maternal and cord blood samples from 174 full-term pregnant women of middle socio-economic status were tested for hemagglutination inhibition (HI) antibody against measles in Delhi during October 1993 to January 1995. None of the mothers had been immunized against measles. RESULTS: Antibody were undetectable in both maternal and cord samples in only 4 (2.3%) pairs. Mean maternal titre was found to be 2.94 Log2. Transplacental concentration and dilution were respectively observed in 34% and 26% of the samples. Cord titres were more often higher than the maternal values only if the maternal values were low. Overall, cord/maternal ratio of mean titre (Log2) was found to be 1.06. Although the age of the mother and parity had had no significant bearing on the transplacental transfer of measles antibody, cord titres were significantly more often higher than the maternal values as the birth weight increased (Chi-square for linear trend = 5.4; p = 0.02). CONCLUSIONS: The study failed to show appreciable concentration of measles antibodies across the placenta.

Adolescent↗
PubMed1997

Synergistic effect of retinoic acid on Sn-PP mediated suppression of heme oxygenase activity in vivo in rats.

The present investigation is designed to probe the influence of excess retinoic acid (50,000 I.U.) and Sn-protoporphyrin (50 mumol/kg bw) along with retinoic acid on the activity patterns of the rate-limiting enzyme, heme oxygenase, of the heme catabolic pathway in the liver, spleen, kidney, brain, heart, and lung of male Wistar rats. Our results are noteworthy as SnPP is being used for the amelioration and management of hyperbilirubinemia, and they emphasize that the combined dosing of retinoic acid and SnPP attenuates the suppression of the activity of HMOX, thereby decreasing plasma bilirubin levels. The features of action of retinoic acid and SnPP together in vivo, i.e., a substantial suppression of the formation of a potentially neurotoxic metabolite, bilirubin, and the enhancement of disposal of the untransformed substrate (heme) of the enzyme that is inhibited, define some of the prerequisites of a therapeutically useful formulation.

Administration, Oral↗
PubMed1997

Immune complexes are potent inhibitors of interleukin-12 secretion by human monocytes.

We have studied the effect of immune complexes (IC) on interleukin (IL)-12 secretion by human monocytes in vitro. Two experimental models of IC were used. IC formed of tetanus toxoid and polyclonal anti-tetanus toxoid antiserum as well as heat-aggregated human serum IgG almost completely inhibited IL-12 (p70 and p40) secretion induced by interferon-gamma and lipopolysaccharide in human blood-derived monocytes. Neutralizing anti-IL-10 antibodies plus indomethacin restored IL-12 secretion in the presence of IC to a high extent, indicating that IL-10 and prostaglandin (PG) partially mediate the IC-induced inhibition of IL-12 secretion. However, neutralization of tumor necrosis factor (TNF)-alpha by specific antibodies also incompletely restored IL-12 secretion. Indeed, monocytes secrete high levels of TNF-alpha upon stimulation by IC. We found that exogenously added TNF-alpha caused a profound inhibition of monocytic IL-12 secretion in the absence of IC, again mediated via the induction of IL-10 and PG. In summary, IC inhibit IL-12 secretion via TNF-alpha-induced IL-10 and PG synthesis. We conclude that IC, typically appearing in the course of chronic inflammatory processes, may influence the balance between Th1 and Th2 responses and may thus contribute to a deprivation of cell-mediated immune responses.

Antigen-Antibody Complex↗
PubMed1997

Hydropericardium syndrome (HPS) in India: a preliminary study on the causative agent and control of the disease by inactivated autogenous vaccine.

Hydropericardium syndrome (HPS) in broiler birds of 3 to 6 weeks of age was recorded for the first time in the Haldwani area of Nainital district (UP) in India in November, 1994. The overall mortality in 6 poultry farms was 61.62 per cent. The disease was experimentally transmitted by bacteria free infected liver homogenate extract passed through membrane filters of 0.22 and 0.1 mu APD. The aetiological agent was inactivated by heat treatment at 56 degrees C for one hour and 80 degrees C for 10 min. A precipitin band was demonstrated in agar gel immunodiffusion and counter immunoelectrophoresis using infected liver homogenate extract as antigen and homologous antisera raised in the laboratory. The disease was effectively controlled by formalinised and heat inactivated autogenous vaccine prepared from the infected livers of birds which died of natural infection.

Animals↗
PubMed1997

Transplacental dilution of tetanus antitoxins in Delhi.

Maternal blood-cord samples from 171 women of middle socio-economic status who had been administered at least two doses of tetanus toxoid (TT), were assayed for tetanus antitoxins by passive haemagglutination (PHA) test. All the mother as well as cord samples had antitoxin titres > or = 0.015IU/ml, the generally accepted minimal protective level; 98 per cent of the mothers and 97 per cent of the newborns had levels > or = 0.125IU/ml. Transplacental dilution was observed in 45 per cent of the samples; the cord/maternal antitoxin ratio (C/M) of geometric mean titre (GMT) was found to be 0.72. The C/M ratio was not affected by the maternal age, parity, birth weight, and number of TT doses administered to mother. The study showed that tetanus antitoxins were diluted on the fetal side of circulation, but the protective levels of antitoxins were achieved in all the newborns as the mothers had received at least two doses of TT before delivery.

Adolescent↗
PubMed1997

Detection, classification, and superposition resolution of action potentials in multiunit single-channel recordings by an on-line real-time neural network.

Determination of single-unit spike trains from multiunit recordings obtained during extracellular recording has been the focus of many studies over the last two decades. In multiunit recordings, superpositions can occur with high frequency if the firing rates of the neurons are high or correlated, making superposition resolution imperative for accurate spike train determination. In this work, a connectionist neural network (NN) was applied to the spike sorting challenge. A novel training scheme was developed which enabled the NN to resolve some superpositions using single-channel recordings. Simulated multiunit spike trains were constructed from templates and noise segments that were extracted from real extracellular recordings. The simulations were used to determine the performances of the NN and a simple matched template filter (MTF), which was used as a basis for comparison. The network performed as well as the MTF in identifying nonoverlapping spikes, and was significantly better in resolving superpositions and rejecting noise. An on-line, real-time implementation of the NN discriminator, using a high-speed digital signal processor mounted inside an IBM-PC, is now in use in six laboratories.

Action Potentials↗
PubMed1997

Fatty and fibroglandular tissue volumes in the breasts of women 20-83 years old: comparison of X-ray mammography and computer-assisted MR imaging.

OBJECTIVE: A method for segmenting MR images of the breast was applied to determine fatty and fibroglandular tissue volumes in breasts of women in different age groups. The results were compared with subjective assessments of breast density from X-ray mammograms in the same patients. MATERIALS AND METHODS: Two experienced mammographers assessed the percentage of fat in the breasts of 40 women who were 20-83 years old. MR images were obtained on a 1.0-T scanner equipped with a bilateral receive-only breast coil. Images were acquired using a three-dimensional T1-weighted gradient-echo sequence with a 1.25 x 1.4 x 2.5 mm resolution. On average, breast parenchyma appeared in 30 images in each breast. Image segmentation was based on a semiautomated, two-compartmental (fatty and fibroglandular tissue) model that accounts for partial volume effects. To validate the accuracy of the MR imaging segmentation technique, we performed a phantom study using an identical imaging sequence. RESULTS: The accuracy of the MR imaging segmentation of the phantom was of the order of 2%. In our subjects, fat content was 42.5% +/- 30.3% (mean +/- SD) on mammography versus 66.5% +/- 18% on MR images. Although we found a significant correlation (r = .63) between the two techniques, mammography poorly differentiated breasts containing less than 45% fat. When our analysis included only dense breasts (i.e., those containing less than 75% fat on MR images), the correlation coefficient decreased to .34. The largest discrepancies between mammography and MR imaging occurred in breasts that had 60-80% fat as measured on MR imaging. CONCLUSION: Fatty and fibroglandular tissue can be differentiated on MR images of the breast with high precision and accuracy, therefore allowing assessment of breast density. The conclusions of researchers who used mammographic density patterns should be reassessed.

Adipose Tissue↗
PubMed1997

Picobirnavirus, a novel group of undescribed viruses of mammals and birds: a minireview.

Picobirnavirus, a novel group of viruses recently detected in children and several species of animals including chickens, are different from the existing members of the family Birnaviridae. Picobirnavirus (PBV) is the tentatively proposed name for the group of these viruses. These viruses are 30-40 nm in diameter and have icosahedral symmetry with triangulation number (T) equal to 3. Their buoyant density in CsCl is 1.4 g/ml. Their genome is bi- or trisegmented double-stranded RNA (dsRNA) with segment lengths of 2.6 and 1.9 kbp for bisegmented and 2.9, 2.4 and 0.9 kbp for trisegmented genomes. The electrophoretic migration profile has considerable heterogeneity. PVBs are detected in diarrhoeic as well as non-diarrhoeic animals, hence, their potential needs further investigation.

Animals↗
PubMed1997

Validity of using slide positivity rate (SPR) in identification of high risk malarious segments in rural areas.

The Expert Committee Report-1995, recommended various parameters for identifying worst malaria affected segments in rural areas, which are mainly based on slide positivity rate (SPR). A analysis of the epidemiological data of Uttar Pradesh was carried out in different settings to study the sensitivity of SPR in identifying high risk areas. The validity of using SPR in the entire range in all settings is examined and appropriate corrective measures suggested.

Blood Specimen Collection↗
PubMed1996

Expression of cell cycle-regulated proteins in prostate cancer.

Markers of cellular proliferation have proven to be useful prognostic markers in several tumor types. Recently, immunoreactivity for cyclins was found to provide an independent marker of tumor proliferation in breast cancer. In this study, we sought to determine the pattern of immunoreactivity for cyclins A, B, E, and Ki-67 in surgically resected prostate cancer and to determine their possible prognostic significance. Twenty-eight tumors of American Urological Association stages B and C were selected for study. Immunoreactivity for cyclins A and B was detected in most tumors and was present at significantly reduced levels as compared with breast cancer. Staining for cyclin E was present in four tumors and was present only in focal areas in two of the four. Such focal variation in expression of cell cycle regulators may reflect genetic instability in a tumor. Immunoreactivity for cyclins A and B was correlated with both Ki-67 index (the percentage of cells with Ki-67 immunoreactivity) and with each other. A Ki-67 index greater than 4.0 was associated with shorter time to prostate-specific antigen-detected relapse (P = 0.026). The fraction of cells staining for cyclins A and B divided by the fraction of cells staining for Ki-67 [(A+B)/K] was highly predictive of relapse, with values less than 0.50 associated with more rapid progression (P < 0.001). This latter result remained statistically significant after controlling for Gleason score by stratification. Our results suggest that immunoreactivity for markers of cellular proliferation may provide useful prognostic information in localized prostate cancer, and they need to be validated in a larger numbers of patients.

Adenocarcinoma↗
PubMed1996

Persistent buccopharyngeal membrane: a report of two cases.

Persistent buccopharyngeal membrane is an extremely rare clinical entity that can be diagnosed easily by simple examination of the oral cavity and confirmed by a lateral contrast x-ray. The abnormality can be easily corrected surgically.

Fatal Outcome↗
PubMed1996

Technetium-99m-DMSA renal cortical scintigraphy to detect experimental acute pyelonephritis in piglets: comparison of planar (pinhole) and SPECT imaging.

UNLABELLED: The purpose of this study was to directly compare the sensitivity and specificity of SPECT and pinhole imaging for the detection of acute pyelonephritis using histology as the standard of reference. METHODS: Bilateral vesicoureteral reflux of infected urine was induced in 16 piglets (32 kidneys) by unroofing the intravesical ureter and subsequently instilling a broth culture of E. coli into the bladder. DMSA scans were obtained by both pinhole and SPECT techniques at 24 hr (4 piglets), 48 hr (5 piglets), 72 hr (4 piglets) and 10 days (3 piglets) after instillation of bacteria into the bladder. Kidneys were harvested immediately after scintigraphy for histopathologic examination. Results of the SPECT images, pinhole images and histologic findings were interpreted independently in a blinded fashion. The images of each kidney were classified as positive or negative for pyelonephritis regardless of the severity and number of lesions. To evaluate accuracy of SPECT and pinhole imaging for the detection of individual lesions, each kidney was arbitrarily divided into three zones (upper, middle and lower). Image findings were then compared with the pathology results for the presence or absence of pyelonephritis in each zone. RESULTS: Histopathology revealed pyelonephritis in 24 of 32 kidneys (58 of 96 zones). The sensitivity of the DMSA scan for detection of affected kidneys was 92% for SPECT and 83% for pinhole; overall accuracy was 88% for both. The sensitivity of SPECT for the detection of affected renal zones was slightly better than pinhole imaging (91% compared with 86%), but its specificity was lower (82% compared with 95%) resulting in a similar accuracy. Excluding four piglets where scans were obtained within 24 hr after instillation of bacteria into the bladder, the sensitivity of SPECT and pinhole for the detection of affected kidneys were 95% and 90%, respectively. Their overall accuracy were 96% and 92%. In this subgroup, the sensitivity, specificity and accuracy of SPECT for the detection of involved zones were 96%, 95% and 96%, respectively. The corresponding values for pinhole imaging were 90%, 95% and 92%, respectively. CONCLUSION: Although the sensitivity of SPECT for the detection of acute pyelonephritis is slightly better than pinhole DMSA scan, the overall accuracy of these two imaging techniques is essentially the same.

Acute Disease↗
PubMed1996

Rooting and establishment of in vitro grown shoot tip explants of chickpea (Cicer arietinum L.).

Shoot tip explants of 5.chickpea varieties were evaluated for efficiency of rooting using MS basal medium (1/4, 1/2 and full strength). Maximum rooting was observed in 3 varieties when cultured in MS medium with 1/4 strength. Plantlets thus developed, were further cultured in Hoagland solution (1/4 strength) for 15-20 days which enhanced root number and root length. Such plantlets established well in vermiculite/soil.

Culture Techniques↗