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R Srinivasan

Publications and source records attributed to R Srinivasan.

At least 37 records · Page 2Linked to original sources
PubMed2005

Laboratory evaluation of fipronil against Periplaneta americana & Blattella germanica.

BACKGROUND & OBJECTIVE: In cockroach control, bait formulations are extensively used. Fipronil is one of the broad spectrum insecticides from phenyl pyrazole family available in bait formulation. The compound has been tested under field conditions. However, information on its effectiveness on different surfaces and at various density levels is not known. Therefore, the efficacy of a new formulation of fipronil 0.03 per cent (Goliath gel) was tested under laboratory conditions. METHODS: The bait formulation was tested against Periplaneta americana at the dosages of 0.025, 0.05, 0.1, 0.15 and 0.2 g/m(2), and Blatella germanica at 0.025, 0.05, 0.075, 0.1 and 0.125 g/m(2) on wood, cement, mud and thatch surface with three density levels of cockroaches viz., 5, 10 and 20 numbers/m(2). Mortality after 24 h of exposure was observed daily for five days. RESULTS: Rate of mortality varied between 16.0 and 96.0 per cent in P. americana and 51.0 and 100.0 per cent in B. germanica on different surfaces tested. The mortality rate of P. americana increased line rarly from the dosage 0.025g to 0.15 g/m(2) and at 0.2 g/m(2), it was independent. The LD(80) values of the gel against P. americana at high density were 0.208, 0.246, 0.361 and 0.466 g/m(2) on wood, cement, mud and thatch surfaces, whereas against B. germanica the values were 0.079, 0.081, 0.089 and 0.055 g/m(2) respectively, indicating a significantly (P<0.001) higher efficacy of Goliath gel against B. germanica than P. americana. The results of fitting logistic regression model to the observed percentage mortality with log dose and cockroach density as explanatory variables satisfactorily described the observations at all densities on each surface. The pattern of response to increasing dosages was similar for all the three density levels on each of the surfaces in P. americana and B. germanica. INTERPRETATION & CONCLUSION: The effectiveness assessed against P. americana and B. germanica using logistic regression model suggested that the gel when applied at the appropriate dosages on wood, cement, mud and thatch surfaces could cause >80 per cent mortality of these species in dwellings having these types of surfaces.

Animals↗
PubMed2005

Primary papillary carcinoma of the thyroglossal duct cyst--a case report.

Thyroglossal duct cyst is the most common developmental anomaly of the thyroid gland, presenting as a mid line neck swelling. Malignancy arising in them is a rare event, with papillary thyroid carcinoma being the commonest. Thyroglossal duct cyst carcinomas are usually asymptomatic and are not suspected preoperatively in most instances, hence the need for surgical excision and careful pathological examination of these cysts. We present a case of a 57 year old lady who underwent a Sistrunk procedure for the removal of thyroglossal duct cyst, which was responsible for a progressive mid line neck swelling of 2 months duration. The thyroid gland was normal. Histological examination of the excised cyst showed a papillary thyroid carcinoma arising in the thyroglossal duct cyst. Long term survival of patients with thyroglossal duct cyst carcinoma is excellent.

Carcinoma, Papillary↗
PubMed2004

Optical characterization of mammalian tissues by laser reflectometry and Monte Carlo simulation.

The optical characterization of various goat organs/tissues, by measurement of the spatial variation of the diffuse reflectance from the surface by laser multi-probe reflectometer, is carried out. For determination of the optical parameters, these profiles are matched by iterative procedures with that obtained by Monte Carlo simulation by best-fit procedure with chi value 0.99. The first set of measurements is carried out with milk phantom. Thereafter, the absorption and scattering coefficients and anisotropy parameter of goat's heart, lungs, kidney, liver, spleen, skeletal muscle, brain and adipose tissues are measured. These parameters vary over a wide range, which is in agreement with results reported by others. Based on these data, their laser scattering profiles along the depth in terms of depth of penetration (DP) and maximum scattered beam width (MSBW) are determined. These are maximum (0.030 and 0.038 m) for kidney and minimum (0.007 and 0.006 m) for spleen, respectively. The backscattered intensity measured 0.002, 0.004 and 0.006 m away from the beam entry point shows the maximum contribution from the respective depths, irrespective of the nature of the organs/tissues.

Animals↗
PubMed2004

Multislice tomographic imaging and analysis of human breast-equivalent phantoms and biological tissues.

A laser transillumination tomographic system, consisting of electrical, optical, mechanical, and software components, to obtain multislice images of tissue-equivalent breast phantoms and biological tissues, is developed. The tissue-equivalent phantoms are prepared from paraffin wax mixed with wax color pigments by matching their surface backscattered profiles as measured by multiprobe laser reflectometer, with that of respective tissues. The optical parameters of these phantoms are determined by matching their reflectance profiles with that as obtained by Monte Carlo simulation of optical scattering. For multislice tomographic analysis conical breast phantoms of height 80.0 mm and 80.0 mm base diameter with inclusions of different optical properties and dimensions are developed. The resolution of the inclusions in the tomograms depends on their sizes and optical parameters. The minimum size of the inclusion as detected by this procedure in a slice of diameter 50.0 mm is 3.0 mm. The structural variation as observed in the tomograms of phantoms of combination of biological tissues indicates its possible applications in detecting the abnormalities developing in human healthy soft tissues.

Algorithms↗
PubMed2004

Improved survival in steroid-refractory acute graft versus host disease after non-myeloablative allogeneic transplantation using a daclizumab-based strategy with comprehensive infection prophylaxis.

Approximately 15% of patients undergoing non-myeloablative allogeneic haematopoietical cell transplantation (NMHCT) develop steroid-refractory acute-graft versus host disease (aGVHD), a usually fatal complication. We encountered 18 cases of steroid-refractory aGVHD in 146 patients, undergoing NMHCT from a related human leucocyte antigen-compatible donor following cyclophosphamide/fludarabine-based conditioning. Our initial cohort of steroid-refractory aGVHD patients treated with antithymocyte globulin (ATG) and mycophenolate mofetil (regimen-1: n = 6) had high GVHD-related mortality. Therefore, we investigated an alternative strategy for subsequent patients developing this complication (regimen-2: n = 12), consisting of daclizumab (alone or combined with infliximab/ATG) and targeted broad spectrum antibacterial and aspergillus prophylaxis in conjunction with rapid tapering of steroids to minimize opportunistic infections. In a retrospective analysis, patients receiving regimen-2 were significantly more likely to have complete resolution of GVHD compared with those receiving regimen-1 [12/12 (100%) vs. 1/6 (17%); P < 0.001]. When compared with those receiving regimen-1, regimen-2 patients also had a higher probability of survival at day 100 (100% vs. 50%) and day 200 (73% vs. 17%) post-transplant, and improved overall survival (median 453 d vs. 42 d from aGVHD onset; P < 0.0001). GVHD-related mortality was 89% for regimen-1 patients vs. 17% for regimen-2 patients (P < 0.0001). These data suggest that a co-ordinated approach using immunoregulatory monoclonal antibodies, pre-emptive antimicrobial therapy and judicious steroid withdrawal can dramatically improve outcome in steroid-refractory aGVHD.

Adolescent↗
PubMed2004

Morphological and immunohistochemical analysis of ductal plate malformation: correlation with fetal liver.

AIMS: Ductal plate malformation (DPM) is the persistence of excess of embryonic bile duct structures in the portal tracts. Most of the congenital diseases of intrahepatic bile ducts represent examples of DPM at different levels of the biliary tree. The aim of the present study was to evaluate the histopathological spectrum and immunohistochemical properties of DPM in various paediatric liver diseases and compare them with those of the normal embryonic ductal plates of human fetuses. METHODS AND RESULTS: All paediatric liver biopsies and autopsied livers of infant deaths and stillbirths over a 5-year period (between 1996 and June 2001) were subjected to histopathological examination to identify ductal plate malformations. A detailed immunohistochemical analysis was carried out in 35 cases of ductal plate malformation and 25 abortuses by using antibodies against cytokeratin (CK)7, 8, 18 and 19, CD34 and type IV collagen. Thirty-nine cases of ductal plate malformation were identified which consisted of extrahepatic biliary atresia with DPM (n = 20), isolated congenital hepatic fibrosis (n = 9), autosomal recessive polycystic kidney disease (n = 5), congenital hepatic fibrosis with autosomal polycystic kidney disease (n = 2), Caroli's syndrome (n = 2) and one case of Ivemark's syndrome. The ductal plate cells stained with CK7, 8, 18 and 19 but not with CD34. CONCLUSION: DPM was present in all intrahepatic bile duct diseases included in this study and in about 26% of cases of extrahepatic biliary atresia. The cytokeratin immunophenotype of the ductal plate in pathological conditions is similar to that of normal embryonic ductal plates of fetuses after 20 weeks of gestation.

Antigens, CD34↗
PubMed2003

Laser reflectance imaging of human forearms and their tissue-equivalent phantoms.

Laser back-scattered radiation from a human forearm is affected by the compositional variation in tissues and was imaged by a reflectance imaging system. The measurement probe consisted of one input fibre and one output fibre, separated by a distance of 0.3 cm. The diffuse reflectance data were collected by placing the probe on the forearm. By interpolation and median filtering of these data, the colour-coded reflectance images of the forearms of ten subjects were reconstructed. For comparative analysis of the mean reflectance, the forearm area was divided into ten regions. The mean normalised back-scattered intensity (NBI) near the ulnar region of the wrist was 4.76 +/- 0.24% and was significantly higher (p < 0.0005) compared with that at other regions, which varied from 3.49 +/- 0.17% to 4.43 +/- 0.14%. Tissue-equivalent phantoms of these, required for the clinical assessment of optical techniques, were constructed using various combinations of paraffin wax and dyes. The matching of the NBI images of these stable and inexpensive phantoms with those of the forearms of the respective subjects showed the similarity of their optical parameters.

Adult↗
PubMed2003

Laser backscattering and transillumination imaging of human tissues and their equivalent phantoms.

Surface backscattering profiles from a human forearm and transmission profiles through a human thumb, of red and near-infrared lasers, were determined. For the preparation of tissue-equivalent phantoms, white paraffin wax mixed with various wax color pigments were used. The surface reflectance profiles of a human forearm were matched with that of the phantom by mixing color pigments in various proportions. The reconstructed surface reflectance image of the phantom prepared by this procedure was similar to that of the human forearm. The transmission tomogram of the human thumb was obtained in fan-beam configuration by a near-infrared laser tomography system. Based on the horizontal scan of this tomogram, a two-layered phantom was made. The color composition of the phantom was so adjusted that its horizontal scan was matched with that of the thumb tomogram. The phantoms of complex tissues, prepared by this procedure, could be used for evaluation and calibration of new optical diagnostic imaging techniques.

Equipment Design↗
PubMed2003

Efficacy of insect parasitoid Dirhinus himalayanus (Hymenoptera: Chalcididae) & insect growth regulator, triflumuron against house fly, Musca domestica (Diptera: Muscidae).

BACKGROUND & OBJECTIVES: In fly management programme chemicals are extensively used. Combined use of insect growth regulator (IGR) and parasitoids would yield a better reduction in fly density, as exposure of fly larvae to sub lethal dose of IGR enhances pupal duration and thereby increases the exposure time for parasitism. The objective of the present study was to explore the additive effect of both Dirhinus himalayanus, an insect parasitoid and triflumuron, an IGR in controlling house fly, Musca domestica. METHODS: In the field trial the study sites were allocated based on two-way ANOVA performed on one year pre-treatment survey. Parasitoid release and IGR treatment were initiated when the growth rate (lambda) of M. domestica was in an increasing trend. Parasitoids were released at a rate of 6 number/m2 for three months (February-April 2000), whereas IGR was applied at a dose of 10 mg/m2 at fortnightly interval from February to December 2000. Control efficacy was assessed using Mulla's formula. RESULTS: Reduction in puparia density was 59.29, 48.67 and 69.08 per cent respectively in areas, where parasitoids, ICR and combination of both IGR and parasitoids were used. Corresponding figures for adult population were 55.69, 49.71 and 77.14 per cent respectively. The per cent reduction in puparia and adult density was significantly (P<0.05) higher in the experimental areas than in the check. When the per cent reduction in adult and puparia density among different experimental areas was compared, it was observed that the reduction in fly density was significantly higher in the areas, where the combination of both parasitoid-IGR (P=0.00102) and IGR (P=0.03175) were used, while in areas where parasitoid (P=0.06191) were released the reduction in fly density was not significant. Similarly, there was a significant reduction in puparia density in areas where both parasitoid-IGR combination (P=0.0001) or IGR (P=0.002) were used, whereas in parasitoid (P=0.0612) released areas it was not significant. INTERPRETATION & CONCLUSION: The results show that the combined use of parasitoid and IGR is effective in reducing puparia and fly density. Therefore, for sustenance of an effective fly control programme, both parasitoid and IGR may be used.

Animals↗
PubMed2002

Malignant pheochromocytoma with cutaneous metastases presenting with hemolytic anemia and pyrexia of unknown origin.

We describe a 43 year old female who presented with pyrexia of unknown origin associated with Coomb's negative hemolytic anemia and impaired liver function tests of six months duration. A routine abdominal computerised tomographic scan showed a mass in the left adrenal which was excised at laparotomy and histologically diagnosed as pheochromocytoma. The hemolysis continued to worsen with development of resistance to steroid therapy. Subsequently she developed multiple firm to hard painless cutaneous nodules which were aspirated for cytologic examination. The cytology picture was that of a neuroendocrine tumour with cell morphology similar to that of the adrenal pheochromocytoma. Such an association of hemolytic anemia, pyrexia and cutaneous metastases in a case of malignant pheochromocytoma has not been described earlier in the medical literature.

Abdomen↗
PubMed2002

Development of biological tissue-equivalent phantoms for optical imaging.

Optical characteristics of freshly isolated tissues depend on their color and composition. The surface backscattered profile, which account for the tissue compositional variation in fresh excised sheep's heart, lungs, bone and muscle, were measured by multi-probe reflectometer. Optical phantoms were prepared from paraffin wax by mixing a specific combination of wax color materials till the surface backscattered profile of these matched with that of the biological tissues. The optical parameters absorption coefficient (micro(a)), reduced scattering coefficient (micro(s)) and anisotropy factor (g) of these phantoms, are the same as that of biological tissues and are obtained by matching their surface backscattered profiles with that as simulated by Monte Carlo procedure. The maximum and minimum values of absorption coefficient are for the phantoms of lungs (1.0 cm(-1)) and muscle (0.02 cm(-1)), whereas, for scattering coefficient these values are for muscle (21.2 cm(-1)) and bone (13.08 cm(-1)).

Animals↗
PubMed2001

Alternative roles for interferon-gamma in the immune response to DNA vaccines encoding related melanosomal antigens.

Tyrosinase-related proteins-1 and -2 (gp75/TRP-1 and TRP-2) are melanosomal membrane glycoproteins recognized by antibodies and T-cells from patients with melanoma. Xenogeneic DNA immunization against gp75/TRP-1 generates antibody-dependent tumor immunity and autoimmune depigmentation. In contrast xenogeneic TRP-2 DNA immunization induces immunity mediated by CD8+ T-cells. The role of IFN-gamma in the generation of tumor immunity and autoimmune depigmentation in these two models was investigated. No tumor protection and minimal depigmentation was observed after immunization with human TRP-2 DNA in mice deficient in IFN-gamma ligand. Repletion with recombinant murine IFN-gamma restored tumor immunity. Experiments using IL4 deficient mice demonstrated that tumor immunity was unaffected but that autoimmune depigmentation was potentially accelerated, consistent with down-modulation of autoimmunity against TRP-2 by IL4. In contrast, IFN-gamma was not required for the generation of immunity to gp75/TRP-1. In fact, exogenous IFN-gamma ablated autoantibody responses against gp75/TRP-1 after xenogeneic DNA immunization, consistent with a down-regulatory effect of IFN-gamma. These results show that immunity to TRP-2 following DNA immunization uses an IFN-gamma-dependent Th1 pathway, but immunity to gp75/TRP-1 is down-regulated by IFN-gamma.

Animals↗
PubMed2001

Ultrafast diffraction and structural dynamics: the nature of complex molecules far from equilibrium.

Studies of molecular structures at or near their equilibrium configurations have long provided information on their geometry in terms of bond distances and angles. Far-from-equilibrium structures are relatively unknown-especially for complex systems-and generally, neither their dynamics nor their average geometries can be extrapolated from equilibrium values. For such nonequilibrium structures, vibrational amplitudes and bond distances play a central role in phenomena such as energy redistribution and chemical reactivity. Ultrafast electron diffraction, which was developed to study transient molecular structures, provides a direct method for probing the nature of complex molecules far from equilibrium. Here we present our ultrafast electron diffraction observations of transient structures for two cyclic hydrocarbons. At high internal energies of approximately 4 eV, these molecules display markedly different behavior. For 1,3,5-cycloheptatriene, excitation results in the formation of hot ground-state structures with bond distances similar to those of the initial structure, but with nearly three times the average vibrational amplitude. Energy is redistributed within 5 ps, but with a negative temperature characterizing the nonequilibrium population. In contrast, the ring-opening reaction of 1,3-cyclohexadiene is shown to result in hot structures with a CC bond distance of over 1.7 A, which is 0.2 A away from any expected equilibrium value. Even up to 400 ps, energy remains trapped in large-amplitude motions comprised of torsion and asymmetric stretching. These studies promise a new direction for studying structural dynamics in nonequilibrium complex systems.

Journal Article↗
PubMed2001

Direct imaging of transient molecular structures with ultrafast diffraction.

Ultrafast electron diffraction (UED) has been developed to study transient structures in complex chemical reactions initiated with femtosecond laser pulses. This direct imaging of reactions was achieved using our third-generation apparatus equipped with an electron pulse (1.07 +/- 0.27 picoseconds) source, a charge-coupled device camera, and a mass spectrometer. Two prototypical gas-phase reactions were studied: the nonconcerted elimination reaction of a haloethane, wherein the structure of the intermediate was determined, and the ring opening of a cyclic hydrocarbon containing no heavy atoms. These results demonstrate the vastly improved sensitivity, resolution, and versatility of UED for studying ultrafast structural dynamics in complex molecular systems.

Journal Article↗
PubMed2001

Stiles-Crawford effect of the first kind: assessment of photoreceptor alignments following dark patching.

Properties of presumed mechanisms controlling photoreceptor alignments are partially defined. A phototropic mechanism normally dominates alignment, but do modest changes in orientations occur with dark patching? Here, new photopic Stiles-Crawford (SCE-I) determinations were made before patching (pre-patch), just after 8-days of dark-patching (post-patch), and 3 days after patch removal (recovery test). We tested at 0, 11 and 22 degrees in the temporal retina of both eyes. Ten eyes of adult subjects were tested. SCE-I peak positions and Stile's parameter 'rho' were assessed. Dark-patching effects were small. Observations revealed meaningful corrective alignment overshoots with recovery in the light. Results suggest (1) the presence of multiple weak mechanisms affecting receptor alignments in the dark; (2) the phototropic mechanism to be dominant in the light; (3) the need for multiple test loci to be sampled in such studies, and (4) small changes in the SCE-I in the pupil plane can reflect meaningful events occurring at the retina.

Adaptation, Ocular↗
PubMed2001

Intracellular expression of the truncated extracellular domain of c-erbB-3/HER3.

The ERBB3 gene is expressed as a 6.2- and a 1.4-kb transcript. The former encodes the full-length transmembrane protein and the latter a truncated extracellular fragment consisting of 140 amino acids of the c-erbB-3 protein followed by 43 unique residues. We have examined the expression of the two ERBB3 transcripts by Northern blotting in cancer cell lines and normal human fetal and adult tissues. We expressed the truncated receptor fragment and showed that it was glycosylated, probably with a single N-linked complex sugar chain, and that the protein was a 58-kDa disulphide-linked dimer. We were able to crosslink iodinated neuregulin (NRG)-1beta to the full-length solubilised receptor but not to the truncated dimeric protein. Using Western blot analysis, the truncated protein was shown to be present in cell lysates and, using immunoelectron microscopy, in vesicular structures within cells and associated with the plasma cell membrane.

Animals↗
PubMed2001

Maximal acid reflux control for Barrett's oesophagus: feasible and effective.

UNLABELLED: The treatment of patients with Barrett's oesophagus is controversial. Debate exists regarding the use and value of high dose acid suppression as the standard of practice. Despite prolonged use of high dose proton pump inhibitors (40 mg omeprazole, 60 mg lansoprazole), most studies have shown no convincing evidence of significant regression of Barrett's length. These studies, however, have used fixed doses of proton pump inhibitors and did not regularly document control of oesophageal acid exposure. AIM: To determine whether regression of Barrett's epithelium can be achieved with documented maximal acid suppression. METHODS: We have prospectively followed nine patients with Barrett's oesophagus (eight male; mean age 60 years) for more than 1 year. They were all treated using medical therapy with pH monitoring documenting oesophageal acid exposure over 24 h < 1.6% of the time, and with two or more esophagogastroduodenoscopies performed by the same endoscopist. RESULTS: Acid control was individually tailored and achieved with proton pump inhibitor b.d. (omeprazole 20 mg or lansoprazole 30 mg) and ranitidine at bedtime (HS) (Ran) if necessary. All nine patients (100%) showed some evidence of regression. All nine patients (100%) showed a decrease in Barrett's length (mean 2 cm, range 1-3 cm). Six out of nine (66.67%) patients showed evidence of squamous islands on the last oesophagogastroduodenoscopy. The mean total distal oesophageal acid exposure was 0.38% (range: 0-1.5%). The mean follow-up of patients was 54 months (range: 13-118 months). CONCLUSIONS: Consistent and individually tailored maximal acid suppression documented by pH-metry is achievable and may result in decreased length and development of squamous islands in patients with Barrett's epithelium. This approach should be further evaluated as potentially the preferred medical treatment for these patients.

2-Pyridinylmethylsulfinylbenzimidazoles↗