Development and establishment of a parallel plate ionization chamber as a transfer standard for measurement of dose to tissue in beta radiation fields.

A parallel-plate ionization chamber (PPC) with a nominal volume of 8.16 cm³ was developed based on theoretically simulated design parameters. Its purpose is to serve as a transfer standard for dosimetry in a beta radiation field. The entrance window of the PPC consists of an aluminized Mylar sheet with a thickness of 1.4 mg/cm2. The collecting and guard electrodes are created by applying a graphite coating on a Poly Methyl Methacrylate (PMMA) substrate with a thickness of 5 mm. The nominal sheet resistance of the graphite-coated PMMA substrate was measured using a four-probe technique and found to be approximately 800 Ω per square (Ω/□). Dosimetric characterization of the PPC was performed in the ISO 6980 reference beta radiation field, utilizing 90Sr-90Y and 85Kr beta radiation sources. The assessment included studies on short-term stability, linearity, current-to-voltage characteristics, stabilization time, and leakage current. The PPC was calibrated and established as a transfer standard using the 'Extrapolation Ionization Chamber,' recognized as an absolute standard for dose to tissue in 90Sr-90Y and 85Kr beta sources within the laboratory. The calibration coefficient of the PPC indicates an energy dependence of 0.6 % for 90Sr-90Y and 85Kr beta sources.

Proton induced activation studies in the carbon steel composites.

The number of accelerator installations has increased significantly in the last decade and requirements are consistently increasing. In these facilities neutrons and high energy charge particle induced reactions are possible with the metallic enclosures made up of natural Fe or steel composites used as structural components or shielding materials. Present study aims to generate a dose rate profile of the induced activations and quantify the induced radionuclide concentrations in the low carbon steel composites. A comparison of the radionuclide concentrations generated in the metallic Fe and SS-304 composite is also presented for a judicious material selection to minimise the radiation concerns.

Clinical outcome of anterior cruciate ligament reconstruction with modified transtibial and anteromedial portal.

Arthroscopic ACL reconstruction is the current standard care of treatment for anterior cruciate ligament (ACL) injuries. Modified transtibial (mTT) and anteromedial portal (AMP) techniques aim at the anatomical placement of femoral tunnel. Controversy existed in the literature with regard to the outcome of these techniques. Hence, we designed a retrospective comparative study to analyse the clinical and functional outcomes of mTT and AMP techniques. We hypothesized that there would be no difference between the clinical and functional outcomes in mTT and AMP techniques. This retrospective observational study was conducted in consecutive patients who underwent arthroscopic ACL reconstruction using semitendinosus-gracilis (STG) quadrupled graft in our tertiary care centre with a minimum follow-up of two years. Out of 69 patients, 37 had undergone ACL reconstruction by mTT technique and remaining by AMP technique. All the patients were assessed clinically by anterior drawer, Lachman's, pivot shift and single-legged hop test. Lysholm Knee Scoring Scale and International Knee Documentation Committee (IKDC) subjective knee evaluation score were used for the functional status. Knee instability was assessed objectively by KT-1000 arthrometer. There was no statistically significant difference in baseline demographic characteristics between mTT and AMP groups. At the end of 2 years, no statistically significant difference was noted in the anterior drawer and Lachman's test. Though not significant, IKDC scores and Lysholm's scores showed a better outcome in the AMP group when compared to the mTT group. AMP group showed significantly better outcome with KT-1000 arthrometer. Based on the results obtained, we presume that overall both mTT and AMP have similar functional outcome. However, as AMP technique offers significantly improved subjective rotational stability on pivot shift test, better hop limb symmetry index and KT 1000 readings compared to mTT, we suggest AMP over mTT.

STUDY OF EFFECTIVENESS OF SHELTERING FROM RADIATION EXPOSURE DUE TO ACCIDENTAL RELEASE OF RADIOACTIVITY.

Sheltering is one of the important protective actions as a part of emergency response during the early phases of an accident-mostly precautionary in nature. Sheltering via structural shielding reduces the direct exposure from plume/cloud shine and ground shine doses as well as the airborne radioactivity concentration and hence inhalation dose. The present study was aimed at estimating the shielding factor in the case of Indian houses for external exposure pathways using the FLUKA Monte Carlo based radiation transport code. Furthermore, the dose reduction factor due to exposure from the inhalation pathway was estimated using an indoor aerosol model. These factors were assessed for the three major types of dwellings, and they provided important inputs for decision-making for sheltering or evacuation in case of any sudden release of radionuclides into the environment.

Development of a rapid technique for sequential separation of plutonium/americium in nasal swab using solvent extraction and liquid scintillation spectrometry.

A rapid radiochemical method has been developed for estimation of plutonium and americium in nasal swab using extractive liquid scintillation spectrometry. The method involves solvent extraction of plutonium and americium from pre-treated nasal swab using 0.2 M Di-(2-ethylhexyl)phosphoricacid prepared in toluene scintillator & back extraction of americium in aqueous phase using 0.35 M HNO3. Activity assessment was carried out using liquid scintillation spectrometry. Overall recovery obtained was 96% for plutonium and 76% for americium with a sample turnaround time of 3 h.

Effect of electrode separation and electrode backscatter thickness of a parallel plate ionization chamber on the measurement of dose to tissue in beta radiation fields.

Plane parallel plate ionization chamber (PPC) is used in dosimetry especially for beta particles and low energy electron beam. The response of the PPC is affected by the electrode separation, thickness and material of backscatterer. The effect of electrode separation arises due to the well-known inscattering effect of electron which causes fluence perturbation inside the chamber cavity. The perturbation is caused due to reduced electron scattering in the chamber cavity compared to an ideal phantom material and it depends on the thickness of the cavity. Furthermore, the response of PPC also gets affected by the material behind the air cavity. Variation in the response depends on the thickness and the atomic number of the material behind collecting electrode of the PPC. The theoretical studies on the effect of collecting electrode backscatter thickness and electrode separation on the response of a PPC used as a transfer standard in ISO 6980 reference beta radiation field from 85Kr, 90Sr-90Y and 106Ru-106Rh radionuclides are presented. Multi-particle transport code FLUKA is used for the studies. The Polymethyl Methacrylate (PMMA) plate having 3.5 mm thickness is found to provide full backscatter for the above beta radionuclides. It is also observed that even for a well-guarded PPC, as the chamber electrode separation increases, the measured depth dose curve deviates from the ideal depth dose curve and the effective point of measurement (EPOM) of the PPC shifts towards downward direction from chamber reference point. It is also observed that the deviation between ideal and measured depth dose curve (related to EPOM shift) depends on the cavity thickness of the PPC. In the present work, optimization of design parameters of a PPC is carried out to establish it as a transfer standard in compliance with ISO 6980 for the standardization of reference beta radiation fields from 85Kr, 90Sr-90Y and 106Ru-106Rh radionuclide.

Bifocal Stabilisation of Acute Acromioclavicular Joint Dislocation using Suture Anchor and Temporary K-Wires: A Retrospective Analysis.

Introduction: The acromioclavicular joint (ACJ) is a major link connecting the upper limb to the torso. The acromioclavicular and coracoclavicular (CC) ligaments help in stabilising the joint. We feel it is prudent to address both these ligament injuries, to achieve optimum result. This study was undertaken to analyse the results of a simple frugal surgical technique we used to deal with this injury considering stabilisation for both these ligaments. Materials and methods: In this retrospective study, skeletally mature patients with Type III, IV or V ACJ dislocations who underwent open reduction and stabilisation of the joint with temporary K-wires, repair of the capsule and augmentation of CC ligaments with suture anchors were included. Clinico-radiological and functional outcome was evaluated. Functional assessment of the upper limb was analysed using the Disabilities of Arm, Shoulder, and Hand Score (DASH), Constant shoulder score (CSS) and Oxford shoulder score (OSS). Results: Clinical and radiological evaluation of the 32 patients who had completed two years from the index surgery, was done. Out of the 37 patients included initially, five were lost in follow-up. Majority of the subjects included were males and type V was the most common injury. Mean pre-operative CC distance on the affected side was 13.92±4.94mm. In the immediate post-operative radiograph, it was 7.63±2.08mm and in the final follow- up was 9.36±2.75mm. Measurements were taken by two independent investigators and inter, and intra-observer reliability were analysed by Interclass correlation coefficient. Excellent functional outcome was noted despite the 1.81±1.50mm average loss of correction. At final follow-up, mean DASH score was 4.67±4.18, Oxford shoulder score was 44.06±2.44 and Constant shoulder score was 86.37±5.81. The severity of the injury had no significant effect on the functional outcome post our method of stabilisation and rehabilitation. Conclusion: Bifocal fixation restores the multidirectional stability of the disrupted ACJ. Adequate radiological reduction, good functional outcome and simplicity of execution make this technique an undemanding one for use in regular practice.

Simulation study on radiation fields around targets to apply CR-39 for photo-neutron measurement in electron accelerator near the threshold energy.

Photo-neutron production in electron accelerator near the threshold energy has been studied by Monte Carlo simulation using the FLUKA code. A pencil beam of 10 MeV electron was incident normally on W, Ta, Pb and Bi targets and a CR-39 detector attached to the target was used as scoring region. In the simulation, photon and neutron spectra, yield and their spatial distribution, fast neutron fluence above 100 keV, total dose and neutron dose deposition were estimated for these metallic targets. The photon emission was found to be forward peaked whereas the neutron emission was isotropic in nature. The photon yield was found to be 5 to 6 orders of magnitude higher than that of neutrons. In W and Ta, the photon yield is maximum for 1.5 mm thickness whereas for Pb and Bi, the photon yield is highest at 2 and 2.5 mm respectively. The total neutron yield was highest for W and lowest for Pb whereas highest number of fast neutrons above 100 keV was for W followed by Bi, Pb and Ta. Production of significant number of fast neutrons above 100 keV suggests the possibility of the use of CR-39 detector for measurement of these neutrons. The total dose deposition was found to be highest for Bi followed by Pb, Ta and W whereas the neutron dose equivalent was highest for W followed by Pb, Bi and Ta. This simulation study will be useful for neutron dosimetry, estimation of source term, implementation of CR-39 for measurement and other radiation protection aspects in the vicinity of an electron accelerator.

A new highly sensitive low-Z LiF-based OSL phosphor for radiation dosimetry.

A new low-Z lithium fluoride-based optical stimulated luminescent (OSL) phosphor is developed. The phosphor shows good OSL properties, and its sensitivity is comparable with that of the commercial Al2O3:C (Landauer, Inc.) phosphor. For the luminescence averaged over initial 3 s, blue stimulated luminescence (BSL) and green stimulated luminescence (GSL) sensitivities were found to be 0.27 and 4 times, respectively, than that of Al2O3:C (Landauer, Inc.). The BSL decay is fast, and the whole signal decays within 3 s; the GSL decay is relatively slow, and the signal decays in 25 s. The fast decay, good sensitivity, good linearity and its near tissue equivalence (Zeff ∼8.14) will make this phosphor suitable for radiation dosimetry particularly in personnel as well as in medical dosimetry.

Na2SiF6:Cu,P: a new OSL phosphor for the radiation dosimetric applications.

A new Cu,P-doped, sodium fluorosilicate-based optically stimulated luminescence (OSL) phosphor is developed. This phosphor shows good OSL properties, and the sensitivity is comparable with that of the commercial Al(2)O(3):C (Landauer, Inc.) phosphor. For the luminescence averaged over initial 1 s, blue-stimulated luminescence and green-stimulated luminescence sensitivities were found to be 0.76 and 3.8 times, respectively, of Al(2)O(3):C (Landauer, Inc.) with 28 % of post-irradiation fading in 3 days and nil thereafter. The simple preparation procedure, fast decay, very good sensitivity and moderate fading will make this phosphor suitable for radiation dosimetry, using OSL.

Prevalence of diabetes mellitus in a rural population of Goa, India.

BACKGROUND: We aimed to estimate the prevalence of diabetes mellitus and study the associated factors in a rural population in Goa, India. METHODS: A cross-sectional study was done in the rural area of Mandur, Goa. Participants>20 years of age were selected by systematic random sampling. They were interviewed with the help of a structured, pretested questionnaire. This was followed by clinical examination, anthropometry and relevant laboratory investigations. Diabetes mellitus was defined as per the American Diabetes Association (ADA) criteria. Statistical analysis was done using the SPSS software package (version 14.0). RESULTS: The prevalence of diabetes mellitus in the study population was 10.3% (130/1266) with a prevalence of 8.4% among men and 12% among women. On bivariate analysis, the prevalence of diabetes mellitus was found to be significantly associated with age, occupation, family income, family history of diabetes, smoking, obesity, hypertension, and high serum cholesterol and triglycerides levels. Multiple logistic regression analysis identified age, family history, hypertension, smoking, total cholesterol and triglyceride as the Independently associated variables for diabetes mellitus. CONCLUSION: Innovative community outreach programmes are required to create awareness, and for screening and treatment of diabetes mellitus to curb the growing epidemic of diabetes in the population.

Prevalence of human cysticercosis and taeniasis in rural Goa, India.

A cross sectional study among 450 individuals selected by strafified random sampling was carried out in rural Goa to find out the prevalence of cysticercosis and taeniasis, as well as to study the role of various factors associated with this diseases. The study participants were administered a pre-tested structured questionnaire and subsequently blood and stool samples were examined. SPSS software was used to analyze the data statistically. The sero-prevalence of cysterosis was 22.4%, which increased with age. Prevalence of taeniasis was 9.7% by stool examination. Individuals with taeniasis were thrice more likely to have cysticercosis; however no association between sero-positivity for cysterosis and pork consumption as well as religion could be established. The study confirmed a high sero-prevalence of cysticercosis in Goa underscoring the need to general awareness about good cooking habits and sanitation.

A prospective study of surgical site infections in a teaching hospital in Goa.

INTRODUCTION: Surgical Site Infections contribute significantly to increased health care costs in terms of prolonged hospital stay and lost work days. The problem was largely unexplored in an apex medical institute in Goa. AIMS AND OBJECTIVES: To estimate the incidence, and study the bacteriology and the factors associated with SSI in the study setting. SETTINGS AND DESIGN: Prospective study in the surgical wards of an apex medical teaching hospital in Goa. MATERIALS AND METHODS: Clinico-bacterilogical follow-up of 114 post-operative cases to the development of SSI, as per the CDC criteria (1991). Incidence was expressed as the infection rate per 100 operations. Antibiotic sensitivity testing was done using the disc diffusion method. STATISTICAL ANALYSIS: Association was tested by applying the Student t-test and the Chi-square test of significance, and the strength of association expressed as the Odd's Ratio. RESULTS: The overall SSI rate was estimated to be 30.7%; 5.4% for clean, 35.5% for clean-contaminated, and 77.8% for contaminated operations. Seventy-nine per cent of the isolates were gram-negative and almost 64% demonstrated polyantimicrobial resistance. CONCLUSIONS: The study emphasizes the need for the evidence-based infection control and antibiotic prescription policies in the hospital.

Frequent inactivation of the cyclin-dependent kinase inhibitor p18 by homozygous deletion in multiple myeloma cell lines: ectopic p18 expression inhibits growth and induces apoptosis.

Multiple myeloma (MM) is a clonal neoplasm of plasma cells which offers an excellent model to study multistep molecular oncogenesis. In 20-25% of primary tumors and cell lines examined, cyclin D1 is overexpressed due to the translocation t(11;14)(q13;q32). We have characterized cyclin-dependent kinase inhibitor p15 (CDKN2B), p16 (CDKN2A) and p18 (CDKN2C) deletions in cyclin D1-expressing and non-expressing MM cell lines. p18 was found to be frequently deleted (38%); in some cases p18 deletions coexisted with hemizygous p16 deletion. To examine the function of p18 as a putative tumor suppressor in myeloma cells, a zinc-inducible p18 construct was stably transfected into KMS12, a MM cell line with biallelic p18 and monoallelic p16 deletions as well as cyclin D1 overexpression. Ectopic expression of p18 caused 40-45% growth suppression as determined by trypan blue exclusion and MTS assays. p18 induction also resulted in apoptosis, suggesting that inhibition of the cyclin D1/CDK/pRb pathway in these tumor cells could be a crucial step toward the induction of tumor regression via apoptotic cell death. This cell cycle pathway is thus frequently mutated and provides a potentially novel target for gene therapeutic or pharmacologic approaches to human myeloma.

Nesidioblastosis with necrotising enterocolitis: an enigma.

Necrotising enterocolitis with nesidioblastosis is a rare, lethal coexistence during the newborn period. We report this unusual combination leading to surgery: a partial pancreatectomy and resection with primary anastomosis, and discuss the dilemma of the procedure of choice during therapy.

Asymmetric conjoined twins.

Despite recent advances in diagnosis, particularly organ-imaging, and therapeutic options, the management of conjoined twins is still very challenging. We report conjoined twins attached ()end-on" at the lumbo-sacral level and describe the anatomical findings, methods of investigation, and management.

Agenesis of the urinary bladder with cutaneous ectopic ureteric orifice and multiple birth defects.

This is to our knowledge the first case in the world literature of a liveborn baby with a tubular colonic duplication, agenesis of the urinary bladder, urethral atresia, and a single pelvic kidney with its ureter opening directly onto the skin in the region of the natal cleft. A brief review of the embryology is included and an attempt is made to explain the embryologic basis for this anomaly.

Fibrolamellar hepatocellular carcinoma.

Fibrolamellar hepatocellular carcinoma, a histological variant of hepatocellular carcinoma, distinct pathological and clinical features and a better prognosis than other types of hepatocellular carcinoma. We report here a patient who was treated on successful surgically.

NAT2, an essential gene encoding methionine N alpha-acetyltransferase in the yeast Saccharomyces cerevisiae.

N alpha-Acetylation is catalyzed by N alpha-acetyltransferases, which transfer acetyl groups from acetyl coenzyme A to the N termini of most eukaryotic proteins co-translationally. NAT1 and ARD1 from the yeast Saccharomyces cerevisiae (Mullen, J. R., Kayne, P. S., Moerschell, R. P., Tsunasawa, S., Gribskov, M., Colavito-Shepanski, M., Grunstein, M., Sherman, F., and Sternglanz, R. (1989) EMBO J. 8, 2067-2075) were previously shown to encode the major N alpha-acetyltransferase, which act on certain proteins having serine, glycine, and alanine but not methionine termini (Sherman, F., Moerschell, R. P., Tsunasawa, S., and Sternglanz, R. (1993) in Methods in Protein Sequence Analysis (Imahori, K., and Sakiyama, F., eds) pp. 173-181, Plenum Publishing Corp., New York). We have identified a second gene, NAT2, that may correspond to the N alpha-acetyltransferase acting on a subset of proteins having methionine termini. Crude extracts of a series of heat-sensitive mutants (Ts-) were screened for acetylation of a 24-amino acid synthetic peptide Met-Asn-Asn- in vitro. One mutant, nat2-1, out of 115 strains examined, lacked acetyltransferase activity, and the mutation co-segregated as a single gene with the heat-sensitive phenotype. The nat2-1 mutants were deficient in the ability to acetylate Met-Asn-Asn- and Met-Glu-Arg-peptides but were able to N alpha-acetylate Ser-Glu-Phe- and Ser-Tyr-Ser- peptides in vitro. The NAT2 wild-type gene was cloned by complementation of the nat2-1 mutant, and the DNA sequence revealed an open reading frame of 288 amino acids. Gene disruption demonstrated that NAT2 is an essential gene, and hybridization analysis indicated that it is located on chromosome VII. Furthermore, there was limited, but significant identities between the yeast N alpha-acetyltransferases Nat1, Ard1, Nat2, and Mak3, although no common motifs could be identified. We propose that NAT2 encodes the major N alpha-acetyl-transferase acting on certain proteins with only methionine termini, and that N alpha-acetylation of some of these proteins is essential for viability.

Total hepatic vascular exclusion for major hepatic resection.

Use of vascular occlusion techniques during hepatic resection has besides decreasing blood loss improved the feasibility of surgical extirpation of large hepatic tumors. We report successful use of this technique to resect a large hepatoma in the right lobe of the liver. The hemodynamic and biochemical changes in the perioperative period are documented.