A rationale for the rapid extraction of ultra-low-level uranyl ions in simulated bioassays regulated by Mn-dopants over magnetic nanoparticles.

Although the sorption of uranyl ions and other heavy metal ions over magnetic nanoparticles is well reported, the parameters governing the sorption process over the magnetic nanoparticles have not been clearly enumerated. However, to increase the efficiency of the sorption over the surface of these magnetic nanoparticles, it is essential to understand the different structural parameters that are involved in the sorption process. The sorption of uranyl ions and other competitive ions in simulated urine samples at different pH was effectively accomplished over magnetic nanoparticles of Fe3O4 (MNPs) and Mn-doped Fe3O4 (Mn-MNPs). The MNPs and Mn-MNPs were synthesized using an easily modified co-precipitation method and were thoroughly characterised using several techniques, such as XRD, HRTEM, SEM, zeta potential, and XPS. The substitutional doping of Mn (1 to 5 at%) in the Fe3O4 lattice (Mn-MNPs) showed better sorption ability as compared to that of MNPs. The sorption properties of these nanoparticles were mainly correlated with the different structural parameters to understand the roles of surface charge and different morphological parameters. The interaction centres over the surface of MNPs with the uranyl ions were designated and the effects of ionic interactions with uranyl ions for these sites were calculated. Extensive XPS, ab initio calculations and zeta potential studies have provided deep insights into the different aspects that play key roles in the sorption process. These materials showed one of the best Kd values (∼3 × 106 cm3) in a neutral medium with very low t1/2 values (∼0.9 min). The fast sorption kinetics (very low t1/2) makes them amongst the best sorption materials for uranyl ions and optimal for the quantification of ultra-low-level uranyl ions in simulated bioassays.

Monte Carlo simulation of enriched uranium in the lungs of thorax voxel phantom for assessment of enrichment and its effect on dose.

In-vivo lung monitoring is an important technique for the assessment of internal dose of radiation workers handling actinides. At BARC, counting efficiencies (CEs) of detection systems used for estimation of natural uranium in the lungs are evaluated using realistic thorax physical phantoms or computational voxel phantoms. The quantification of 238U and 235U in lungs is done using CEs determined at 63.3 keV and 185.7 keV photon energies respectively. These CEs can also be used for assessment of enriched uranium in the lungs of the workers. In this study, spectra are generated for HPGe array detectors using Monte Carlo simulations of various enriched uranium compositions distributed in the lungs of thorax voxel phantom. A methodology is developed to predict the 235U enrichment from lung spectrum analysis using the ratio of net counts in 185.7 keV and 63.3 keV energy regions. It is possible to estimate enrichments in the range of 2%-30% using the developed method with less than ±9% error. Finally, effect of 235U enrichment on dose assessment using lung monitoring method is studied.

Evaluation of Uncertainties in lung measurements of actinides due to counting statistics.

Counting statistics is an important parameter that can introduce uncertainties in the lung activity measurements of actinides in radiation workers. Evaluation of uncertainties due to counting statistics is practically difficult as it requires monitoring various radiation workers having different levels of lung actinide content, multiple times, each for 50 min of monitoring period. However, different activities in lungs can be simulated by combining uncontaminated male data with LLNL phantom data acquired with 241Am and natural uranium lung sets at various short periods. Therefore, multiple measurements were carried out on realistic thorax LLNL phantom with 241Am and natural uranium lung sets for 15-600 s. The mean counts with the phantom at various time intervals, corresponds to different actinide activities in lungs, assuming they are obtained for 50 min of monitoring interval. Using propagation of error, standard deviations were evaluated for combined phantom and uncontaminated adult male data. The combined standard deviations and mean phantom counts are used to evaluate scattering factors (SFs) for uncertainties due to counting statistics for Phoswich and HPGe array detectors. The SFs due to counting statistics are found to be the function of lung activities of radionuclides as well as energies and yields of the photons emitted by radionuclides. SFs are found to increase with decrease in lung activity. For similar yields photons, SFs are found to be lower for higher energy photons compared to lower energy photons. For photons of similar energies, the SFs are lower when yield is higher compared to lower yield photons.

Hierarchy of DNA immobilization and hybridization on poly-L-lysine using an atomic force microscopy study.

The atomic force microscopy has been used to analyze the immobilization of single stranded DNA on poly-L-lysine-coated glass and subsequent hybridization with complimentary DNA with the Z-threshold parameter and fractal analysis methods. The poly-L-lysine layer, which has a thickness of approximately 7 nm, presents nano-defects that could be critical for DNA immobilization by acting as a nucleation sites for ssDNA and subsequently for dsDNA aggregates. The Z-threshold for the dsDNA aggregates is much larger than for ssDNA, but the statistical fractal dimension is very similar, suggesting a conformal increase of the dimensions of the dsDNA aggregates mainly in the Z-direction, due to an effective ssDNA-ccDNA molecular recognition. This study demonstrates the use of fractal analysis in conjunction with the distribution of heights to evaluate the efficiency of DNA-DNA molecular recognition on surfaces and the impact of nanodefects.

SMGA gels for the skin permeation of haloperidol.

Small molecule gelling agent (SMGA) gels were developed using the gelator GP-1 in the solvents, namely, isostearyl alcohol (ISA) and propylene glycol (PG), to deliver haloperidol through the skin. The concentrations of the drug, haloperidol, the enhancer, farnesol and the gelator, GP-1 are 3 mg/ml, 5% (w/v) and 5% (w/v), respectively. The study employed a three-factor full factorial statistical design to investigate the influence of factor level changes on the permeability coefficient and permeation lag-time of haloperidol. Gels were prepared by raising temperature to 120 degrees C, followed by natural cooling under room temperature of 22+/-1 degrees C. The rheological properties of the gels were examined with a strain-controlled dynamic mechanical method. The in vitro permeation study was conducted with automated flow-through type cells. The gels successfully incorporated the drug and enhancer without losing their aesthetic properties. The in vitro human skin permeation study showed the permeation of the drug in ISA-based gels reached the pseudo steady state faster than PG-based gels and were less affected by gelator. PG-based gels delivered the drug at a faster rate with the incorporation of the enhancer. GP-1 did not influence the drug permeation rate but it increased permeation lag-time. The co-existence of gelator or enhancer increased the lag-time to a larger extent than when used separately. The novel SMGA gels are suitable for topical or transdermal delivery.

Surfactant free fabrication of polymeric nanoparticles by combined liquid-liquid phase separation and solvent/nonsolvent mixing technology.

It is generally agreed that, in most cases, surfactants are required to obtain stable polymeric nanoparticle dispersions. Here, we report a method which can be used to produce surfactant free yet stable polymeric nanoparticle dispersions. This method is based on explored mechanism of selective solvation of nanoparticles and EPD (electron pair donor)/EPA (electron pair acceptor) complexes formed among solvent and nonsolvent molecules. Using polyimide P84 (copolyimide 3,3(') 4,4(')-benzophenone tetracarboxylic dianhydride and 80% methylphenylene diamine+20% methylene dianiline) as the model polymer, this mechanism was realized through a combined liquid-liquid phase separation and solvent/nonsolvent mixing technology. Surfactant-free polyimide nanoparticles (<100 nm) were produced. Experimental details and principles of this technology were given based on the ternary diffusion, the liquid-liquid phase separation and the advanced nucleation and growth theory. Two types of methods [denoted as the forward titration method and the backward titration (BT) method] were examined. It was found that the BT method is extremely helpful to prepare polyimide nanoparticles (<100 nm). As another important aspect, explored stabilization mechanism of the resultant nanoparticle dispersions was supported by the comparative experiments, implying that selective solvation of nanoparticles and EPD/EPA complexes may play key roles in stabilization.

Feasibility studies for assessing internal exposure to 233U.

The potential internal occupational exposure encountered as a consequence of the 232Th-233U fuel cycle are likely to arise predominantly from the inhalation of 232Th, 233U and (232Th + 233U) compounds of absorption Types M and S. In the past, although direct and indirect methods for assessments of internal exposure to 232Th and its daughters were developed, standardised and employed, no such attempts have been made with regard to 233U and 233U + 232Th. Therefore, feasibility studies for assessing internal exposure to 233U have been conducted using three methods: urine bioassay, in vivo counting and measurement of thoron gas in the exhaled breath of a worker. This paper describes details of these studies and discusses the results obtained.

Celiac disease in osteoporotic Indians.

OBJECTIVE: 1) The aim of the study was to identify the atypical celiac disease (CD) in a cohort of symptomatic osteoporotic patients, younger than 55 years of age and 2) To study associated clinical and laboratory features and outcome with gluten-free diet. MATERIAL AND METHODS: We studied 33 patients (F:M = 28:5), mean age 29 years (range 15-52 years) with osteoporosis (WHO diagnostic criteria, T-score less than -2.5 on DEXA scan) from January 2000 - June 2002. Serological screening for CD was done by detecting circulating IgA antibodies to tissue transglutaminase by ELISA. Patients with presence of antibodies to transglutaminase were subjected to biopsy from the 2nd part of the duodenum by upper GI endoscopy. The biopsies were reported independently by two pathologists who were blinded for the serology report. Measurement of mucosal thickness, crypts and villi were done with an ocular micrometer. Other parameters like complete hemogram, serum iron, total iron binding capacity (TIBC), calcium profile, 25-OH-D, parathyroid hormone (PTH) were evaluated. Assessment of clinical and laboratory parameters was performed within 4-12 weeks of starting gluten-free diet (GFD). RESULTS: Thirteen patients had circulating IgA antibodies to transglutaminase. Intestinal biopsies were performed on 11 patients and were consistent with the diagnosis of CD (total villous atrophy--two, subtotal villous atrophy with crypt hyperplasia--nine). Patients with CD had significant anaemia when compared with non-CD osteoporotic patients. Other important observations in these 11 patients were low serum calcium and phosphorus, low 25-OH-D, high PTH. Significant improvement in clinical and laboratory parameters was noted in all patients within 6-12 weeks of starting GFD. CONCLUSION: Symptomatic osteoporotic patients (younger than 55 years of age) especially with associated anaemia should be investigated for CD. Simple measures like omission of wheat from diet (GFD) lead to significant improvement in symptoms within weeks.

Multiple esophageal webs.

Multiple esophageal webs are rare and are described in association with gastroesophageal reflux disease (GERD). We describe a case of multiple esophageal webs secondary to GERD.

Rectal lymphogranuloma venereum in association with rectal adenocarcinoma.

Rectal involvement in lymphogranuloma venereum (LGV) is more common in women. Inguinal bubo is often absent and the patient seeks medical attention only at a late stage when rectal stricture has developed. LGV rectal stricture resembles and is known to predispose to rectal cancer. Hence it is necessary to rule out rectal malignancy in patients with LGV stricture. We report a case of rectal LGV associated with rectal adenocarcinoma.

Unusual features of Helicobacter (Campylobacter) pylori--associated gastritis in India. A study of 200 cases.

Helicobacter (Campylobacter) pylori has been cultured from the antral biopsies of 85-90% of patients of gastritis, gastric ulcer and duodenal ulcer at different centres. Studies conducted all over the world have firmly implicated this organism in the aetiology of active superficial gastritis and recurrences of duodenal ulcer. Two hundred patients with upper abdominal pain, distension, vomiting and/or haemetemesis were subjected to OGD scopy. In 163 of these patients there was endoscopic evidence of gastritis; in 24 there was DU; in 3, GU and in 10 it was normal. Diagnosis of H pylori infection was made by the rapid biopsy urease test which is nearly 100% specific and 98% sensitive. 170 out of 200 patients were positive for H pylori. Among these were 138 patients of gastritis (84.6%); 22 cases of DU (91.6%); 2 cases of GU (66.6%) and 8 in whom endoscopy was normal. Histological examination of the antral biopsy specimens showed mild to severe infiltration of mucosa with lymphocytes and plasma cells. None of the 170 H pylori positive cases showed polymorphonuclear infiltration which has been stressed repeatedly by most Western authors to be characteristic of "active" superficial gastritis associated with H pylori infection. Even in those with a history of dyspepsia of barely 4 weeks duration or less there was no PMN infiltration in the mucosa. Thus the local response to infection by H pylori of the gastric mucosa is different in Indian patients.

Association of peptic ulcer with Helicobacter pylori and the recurrence rate. A three year follow-up study.

Helicobacter pylori is associated with 70-100% of peptic ulcers. Relapse of infection has been shown to cause recurrences of ulcers in a large number of studies. We diagnosed 137 cases of peptic ulcer (121 DU; 16 GU) during a 3 year period. Of these, 117 were positive for H pylori. Sixty six of the 117 cases staying in the vicinity of the Hospital were followed up for a minimum period of 3 months upto a maximum period of 3 years. In 91 examinations there was relapse of H pylori infection and ulcer recurrence was seen in 58 (63%), whereas ulcer recurred only in 6 out of 61 examinations where H pylori had not relapsed (10%). The difference was highly significant by Chi square test. (P less than 0.001).

Relapse of Helicobacter pylori infection after different treatment regimens. A 3-month follow-up study.

Helicobacter pylori infection of gastric antrum is associated with a majority of cases of peptic ulcer (70-100%). Studies have shown that when this organism is eradicated, the recurrence of ulcer falls to less than one-third of those in whom the infection persists or relapses. Monotherapy with bismuth salts, tinidazone or amoxycillin has been shown to result in early relapse and recurrence of ulcers. However, dual or triple therapy regimens are more effective. We conducted a randomised controlled study using tripotassium dicitrato bismuthate (TDB) (10 patients); amoxycillin (combined with ranitidine for ulcer healing) (9 patients) and dual therapy with both amoxycillin and TDB (10 patients). Our study showed that relapse rates at the end of 3 months was significantly less if dual therapy with TDB and amoxycillin is used as compared to TDB alone (p less than 0.05).

Double-blind comparison of the safety and efficacy of famotidine with ranitidine in patients with endoscopically diagnosed peptic ulcer.

In a double-blind randomised trial, 40 patients with active gastric or duodenal ulcer were treated with a single nocturnal dose of famotidine 40 mg or ranitidine 300 mg for 4 to 8 weeks. Antacid tablets were allowed as additional treatment, only if needed, for pain relief. Endoscopy was repeated after 4 weeks, and if the ulcer had not healed at 6 and/or 8 weeks. Relief of upper gastro intestinal symptoms with which the patient presented and the number of antacid tablets consumed, if any, were recorded on weekly basis. Two patients in famotidine group and 5 patients in ranitidine group did not complete the therapy and were considered dropouts. At the end of therapy, ulcers in 100% of the patients receiving famotidine & 93% of patients receiving ranitidine were healed. This difference was not statistically significant. Relief from ulcer related symptoms was rapid in both the groups. None of the patients in either group reported side effects. Overall opinion of investigator was comparable for both the treatments; however, significantly (P = 0.0334) larger proportion (100%) of patients from famotidine group rated it as an excellent therapy compared to only 73% from ranitidine group. Famotidine provides excellent healing of ulcers and early relief of upper gastrointestinal symptoms in Indian patients with peptic ulcer.