Pratik Kumar

Radiation exposure to the patient and operating room personnel during percutaneous nephrolithotomy.

Introduction: The increased use of fluoroscopy during percutaneous nephrolithotomy (PCNL) places the urologist and operating room personnel at an occupational risk for measurable radiation exposure. We evaluated the degree of radiation exposure received by the patient and operating room personnel at our endourology facility during PCNL. Patients and method: The incident radiation dose to the patient and the urologist during 50 consecutive PCNL procedures was monitored using lithium fluoride thermo-luminescent dosimeter chips (TLD chips). A hand held radiation survey meter was used to measure the radiation in air at different positions occupied by various operating room personnel. The approximate distances of the various personnel from the X-ray tube were also measured. Results: PCNL was performed upon 35 males and 15 females. The average time for the procedure was 75 minutes (range: 30–150 min). The mean fluoroscopy screening time during the procedure was 6.04 min (range 1.8–12.16 min) with a mean fluoroscopy tube potential of 68 kVp and a mean tube current of 2.76 mA. The mean radiation exposure dose to the patient was 0.56 mSv (SD ± 0.35), while the mean incident radiation exposure to the finger of the urologist was 0.28 mSv (SD ± 0.13). Conclusion: The various operating room personnel are within safe radiation dose limits during PCNL. Efficient fluoroscopy further reduces the radiation scatter. All occupational personnel should ‘achieve as low as reasonably achievable’ dose by adhering to good practices.

Role of color Doppler indices in predicting disease-free survival of breast cancer patients during neoadjuvant chemotherapy.

The aim of our study was to evaluate whether blood flow in locally advanced and inflammatory breast cancer before and after neoadjuvant chemotherapy using color Doppler ultrasonography can be used to monitor the response to therapy and identify possible correlations between survival and various Doppler indices. Fifty patients with breast cancer underwent Doppler evaluation of the tumor with determination of Doppler indices such as pulsatility index (PI), resistive index (RI), and peak systolic velocity (PSV). RI and PI decreased in 27 (54%) and 20 (40%) patients, respectively, and increased in 23 (46%) and 30 (60%) patients, respectively. Thirty (60%) patients showed a decrease in PSV and 20 (40%) patients an increase. Patients with an intratumoral blood flow velocity increase after chemotherapy had a greater likelihood of local recurrence and metastasis compared with patients in whom flow velocity decreased after chemotherapy. The study also confirmed a greater correlation between Doppler PSV and clinical assessment. Tumor flow velocity measured by Doppler ultrasound can be used as an independent marker of disease-free survival in patients with breast cancer.

Influence of immunoadjuvants and a promiscous T-cell determinant on the immunogenicity of RESA peptide antigen of P. falciparum.

Synthetic peptide antigens representing the repeat sequences of malarial antigens showed poor immunogenicity and protection in clinical trials. In the present study, RESA, an asexual blood stage antigen, containing (EENVEHDA)2 and (DDEHVEEPTVA)2 sequences were chemically linked to a promiscous T-cell determinant (CS.T3) of the circumsporozoite protein of P. falciparum. The synthetic constructs either alone or coentrapped with immunoadjuvants (nor muramyl dipeptide/lauroyl tetrapeptide) were administered in liposomes to mice of varying genetic background and the immunogenicity of different formulations were compared under identical experimental conditions. The RESA peptide formulations containing the T-cell determinant and the adjuvants generated high titre and affinity antibodies in all the strains, as compared to peptide(s) alone. The booster immunization induced a strong anamnestic response in each group. Though the major IgG isotype is of IgG1 and IgG2b interestingly, formulations containing CS.T3 have a higher proportion of cytophilic IgG2b isotype. There was a significant fall in the levels of IgG2b isotype while IgG1 levels were maintained same in the third bleed (day 60, without booster immunization). The mixed peptide group preparation containing the adjuvant is found to be a better immunogen than that of respective peptides itself. The in vitro merozoite reinvasion inhibition assay showed 76-96% inhibition with the formulations containing RESA peptide(s)-CS.T3 and the adjuvant, while with peptides alone the inhibition was 50-56%. This study highlights the importance of an alternative approach for developing peptide based immunogen against malaria.

Role of oxidative stress while controlling iron deficiency anemia during pregnancy - Indian scenario

Iron Deficiency anemia ranks 9th among 26 diseases with highest burden. Asia bears 71% of this global burden. Adverse maternal and birth outcome associated with hemoglobin status renders the issue worth attention. Indian scenario has worsened over the period despite continuous international and national efforts. This indicates some lacunae in the approach and strategies applied. Various reports state that even with maximum effort to increase outreach and monitoring for adherence to Iron schedule, consumer’s compliance remains abysmally low. Recent studies has pointed out biological basis of side effects (gastrointestinal complains and systemic events) as raised oxidative stress for which iron is the key catalyst. Up till now the only target of research has been to raise hemoglobin of pregnant women above 11gm/dl. With the reports of pregnancy specific morbidities i.e. hemorrhage and septicemia with low hemoglobin, eclampsia, small for gestation age, gestational diabetes with higher ranges of hemoglobin, alarm is raised to define optimum range. Use of oxidative stress as biochemical marker with different doses and schedules has been defined because India lack information for its own population upon oxidative stress status when iron is supplemented as per current guidelines. Studies done in India and abroad have defined that too much and too less, both may raise oxidative stress and studies of this sort may provide biochemical scale for optimization. This review therefore has evaluated currently available Indian research and reports to understand the need of future research area. Important findings from other countries have been incorporated for comparison.

A new high sensitivity Na2LiPO4:Eu OSL phosphor

A new high sensitivity Na2LiPO4:Eu optically stimulated luminescence dosimeter (OSLD) material was prepared by a simple solid-state diffusion method. The formation of the material was confirmed by comparing the experimental data with that available in the literature (JCPDF # 80-2110). The dosimetric properties of the phosphor material using a continuous wave-optically stimulated luminescence (CW-OSL) technique were studied. The material was studied for different concentrations of the impurity and also for different heating treatments. The material doped with 1.0 mol% and annealed at 873 K was found to be the most sensitive. The phosphor was found to have all the good dosimetric characteristics, such as tissue equivalence (low-Z, Zeff ∼ 10.8), high sensitivity (∼3 times less than the commercially available Al2O3:C, Landauer Inc., USA and BeO, Thermalox® 995, Materion Inc., USA), low fading (∼6.2% in 40 days), wide range of dose response (0.1–1.0 kGy), excellent reusability, easy optical bleaching (annealing) for its reuse, etc., which makes the material useful for dosimetry of high-energy radiations using OSL. The advantages of our OSLD phosphor are the easily available and inexpensive ingredients and a very simple method of preparation that makes it cost effective as compared to the commercially available OSLD phosphors. Also, it is easy to handle, unlike the Thermalox® 995 (BeO) dosimeters which are very toxic, and require a special method of preparation and handling.

DECT evaluation of noncalcified coronary artery plaque

PURPOSE Composition of the coronary artery plaque is known to have critical role in heart attack. While calcified plaque can easily be diagnosed by conventional CT, it fails to distinguish between fibrous and lipid rich plaques. In the present paper, the authors discuss the experimental techniques and obtain a numerical algorithm by which the electron density (ρ(e)) and the effective atomic number (Z(eff)) can be obtained from the dual energy computed tomography (DECT) data. The idea is to use this inversion method to characterize and distinguish between the lipid and fibrous coronary artery plaques. METHODS For the purpose of calibration of the CT machine, the authors prepare aqueous samples whose calculated values of (ρ(e), Z(eff)) lie in the range of (2.65 × 10(23) ≤ ρ(e) ≤ 3.64 × 10(23)/cm(3)) and (6.80 ≤ Z(eff) ≤ 8.90). The authors fill the phantom with these known samples and experimentally determine HU(V1) and HU(V2), with V1,V2 = 100 and 140 kVp, for the same pixels and thus determine the coefficients of inversion that allow us to determine (ρ(e), Z(eff)) from the DECT data. The HU(100) and HU(140) for the coronary artery plaque are obtained by filling the channel of the coronary artery with a viscous solution of methyl cellulose in water, containing 2% contrast. These (ρ(e), Z(eff)) values of the coronary artery plaque are used for their characterization on the basis of theoretical models of atomic compositions of the plaque materials. These results are compared with histopathological report. RESULTS The authors find that the calibration gives ρ(e) with an accuracy of ±3.5% while Z(eff) is found within ±1% of the actual value, the confidence being 95%. The HU(100) and HU(140) are found to be considerably different for the same plaque at the same position and there is a linear trend between these two HU values. It is noted that pure lipid type plaques are practically nonexistent, and microcalcification, as observed in histopathology, has to be taken into account to explain the nature of the observed (ρ(e), Z(eff)) data. This also enables us to judge the composition of the plaque in terms of basic model which considers the plaque to be composed of fibres, lipids, and microcalcification. CONCLUSIONS This simple and reliable method has the potential as an effective modality to investigate the composition of noncalcified coronary artery plaques and thus help in their characterization. In this inversion method, (ρ(e), Z(eff)) of the scanned sample can be found by eliminating the effects of the CT machine and also by ensuring that the determination of the two unknowns (ρ(e), Ze(ff)) does not interfere with each other and the nature of the plaque can be identified in terms of a three component model.

Production and characterization of human anti-V3 monoclonal antibodies from the cells of HIV-1 infected Indian donors

BackgroundAnalysis of human monoclonal antibodies (mAbs) developed from HIV-1 infected donors have enormously contributed to the identification of neutralization sensitive epitopes on the HIV-1 envelope glycoprotein. The third variable region (V3) is a crucial target on gp120, primarily due to its involvement in co-receptor (CXCR4 or CCR5) binding and presence of epitopes recognized by broadly neutralizing antibodies.MethodsThirty-three HIV-1 seropositive drug naive patients (18 males and 15 females) within the age range of 20–57 years (median = 33 years) were recruited in this study for mAb production. The mAbs were selected from EBV transformed cultures with conformationally constrained Cholera-toxin-B containing V3C (V3C-CTB) fusion protein. We tested the mAbs for their binding with HIV-1 derived proteins and peptides by ELISA and for neutralization against HIV-1 viruses by TZM-bl assays.ResultsWe isolated three anti-V3 mAbs, 277, 903 and 904 from the cells of different individuals. The ELISA binding revealed a subtype-C and subtype-A specific binding of antibody 277 and 903 while mAb 904 exhibited cross reactivity also with subtype-B V3. Epitope mapping of mAbs with overlapping V3 peptides showed exclusive binding to V3 crown. The antibodies displayed high and low neutralizing activity against 2/5 tier 1 and 1/6 tier 2 viruses respectively. Overall, we observed a resistance of the tier 2 viruses to neutralization by the anti-V3 mAbs, despite the exposure of the epitopes recognized by these antibodies on two representative native viruses (Du156.12 and JRFL), suggesting that the affinity of mAb might equally be crucial for neutralization, as the epitope recognition.ConclusionsOur study suggests that the anti-V3 antibodies derived from subtype-C infected Indian patients display neutralization potential against tier 1 viruses while such activity may be limited against more resistant tier 2 viruses. Defining the fine epitope specificities of these mAbs and further experimental manipulations will be helpful in identification of epitopes, unique to clade C or shared with non-clade C viruses, in context of V3 region.

Facile synthesis of KCl:Sm3+ nanophosphor as a new OSL dosimetric material achieved through charge transfer between the defect states

Since precise control of nanoscale features is in high demand, it is being exploited to develop and improve OSL dosimetric materials, where striking improvement might also be expected in lanthanide-doped metal halides. The major challenge in the development of a nanophosphor lies in avoiding the aggregation of a dopant element in host materials, which has long prevented an in-depth exploration for the same purpose. This study focuses on the synthesis and characterization of Sm-doped KCl nanophosphors to develop a novel accession to investigate the highly sensitive trivalent Sm-doped KCl phosphor. Herein, we were able to overcome the aggregation phenomena and we showed that Sm-doped KCl with 0.45 mol% of Sm, which is the optimised dopant concentration, exhibits the high-intensity luminescence performance under blue light stimulation for the gamma doses in the range from 100 mGy to 1000 Gy. This sensitivity is attributed to the uniform nanospheres encapsulated in KCl along with the predominant existence of a trivalent (Sm3+) state, where these conditions can introduce additional defects centres. The presence of these additional defect centres was confirmed by photoluminescence studies, plausibly supporting the charge transfer due to the optical energy between these states, leading to high sensitivity. To establish KCl:Sm as a good OSL dosimetric materials (DM), we investigated fading, reusability, and reproducibility and compared these with those of commercial DM compounds such as Al2O3:C and BeO. Overall, Sm-doped KCl is non-toxic, cost-effective, robust, and a promising candidate for reusable dosimetry.

Non-invasive characterization of coronary artery atherosclerotic plaque using dual energy CT: Explanation in ex-vivo samples

PURPOSE In this study non-calcified plaque composition is evaluated by Dual Energy CT (DECT). Energy Dispersive X-ray Spectroscopy (EDS) has been used to study the Plaque composition. An attempt has been made to explain the DECT results with EDS analysis. METHODS Thirty-two ex-vivo human cadaver coronary artery samples were scanned by DECT and data was evaluated to calculate their effective atomic number and electron density (Zeff & ρe) by inversion method. Result of DECT was compared with pathology to assess their differentiating capability. The EDS study was used to explain DECT outcome. RESULTS DECT study was able to differentiate vulnerable plaque from stable with 87% accuracy (area under the curve (AUC):0.85 [95% confidence interval {CI}:0.73-0.98}] and Kappa Coefficient (KC):0.75 with respect to pathology. EDS revealed significant compositional difference in vulnerable and stable plaque at p < .05. The weight percentage of higher atomic number elements like F, Na, Mg, S, Si, P, Cl, K and Ca was found to be slightly more in vulnerable plaques as compared to a stable plaque. EDS also revealed a significantly increased weight percentage of nitrogen in stable plaques. CONCLUSIONS The EDS results were able to explain the outcomes of DECT study. This study conclusively explains the physics of DECT as a tool to assess the nature of non-calcified plaques as vulnerable and stable. The method proposed in this study allows for differentiation between vulnerable and stable plaque using DECT.

Nanocrystalline BaSO{sub 4}:Eu For Dosimetry of Proton Beams

Nanocrystalline BaSO4 doped with Eu, was prepared by the Chemical Co‐precipitation method. The particle size was calculated by the broadening of the XRD peaks using Scherrer’s formula with particle size around 45 nm. Samples in the form of pellets were irradiated by 150 MeV proton beam with dose range of 0.1 Gy to 325 Gy. Thermoluminescence (TL) glow curves of the irradiated samples were recorded and studied. It has been found that there are two prominent TL glow peaks at 460 K and 495 K. The TL response is sublinear below 1 Gy, linear in the range 1 Gy to 200 Gy and then becomes supralinear for higher doses. The wider linear TL response of nanocrystalline BaSO4:Eu and low fading makes it a superior candidate as a dosimeter to be used for detecting the doses of protons for its various applications in the field of space, therapy and research.