Extraction of the uranyl ion with 3-phenyl-4-benzoyl-5-isoxazolone (HPBI) and neutral donors from dilute nitric acid medium

The extraction behaviour of Uranium (VI) from aqueous nitric acid medium employing 3-phenyl-4-benzoyl-5-isoxazolone (HPBI) has been studied in the presence of various amides, e.g , di-2-ethylhexylacetamide (D2EHAA), di-2-ethylhexylpropanamide (D2EHPrA), di-2-ethylhexylisobutylamide (D2EHiBA) and di-2-ethylhexylpivylamide (D2EHPvA) in toluene medium. The extraction constant (log k ex) for the binary species UO2(PBI)2·nH2O was found to be 1.42±0.14 which is by far the largest amongst the corresponding values known for the other β-diketones. The overall equilibrium constant (log K) for the ternary species UO2(PBI)2·D2EHAA, UO2(PBI)2·D2EHPrA, UO2(PBI)2·D2EHiBA and UO2(PBI)2·D2EHPvA were estimated to be 6.51, 6.21, 6.11 and 5.77 respectively. This trend in equilibrium constants was in accordance with the substitution of the amides as sterically crowded amides show relatively lower equilibrium constant values. The extraction constants follow an inverse correlation with the pK a values of the β-diketonates while the equilibrium constants vary linearly with the size of the amides. The steric factors have been found to play a significant role in the co-ordination of the amides to the uranyl β-diketones when the carbonyl group is a part of the heterocyclic ring. The distribution ratios of the metal were measured in the temperature range 15 to 52 °C using each of the amide donors in combination with HPBI. Calculation of enthalpy and entropy therefrom indicated that the extraction was thermodynamically favoured process and maximum extraction resulted in the case of UO2(PBI)2·D2EHAA.

Extraction of tetravalent neptunium isoxazolonates as their TOPO adducts

The extraction behaviour of Np(IV) by 3-phenyl-4-benzoyl-5-isoxazolone (HPBI) in the presence of tri-n-octyl phosphine oxide (TOPO) was investigated from nitric acid medium. The speciation studies, carried out by the slope analysis method, yielded binary species of the type Np(PBI)4 when only HPBI was used as the extractant and ternary species of the type Np(PBI)4·TOPO when both HPBI and TOPO were used as the extractants. The two-phase extraction constant for the binary species (log k ex) was calculated to be 10.11±0.03, while that for the ternary species was found to be 17.24±0.05. Thermodynamic parameters for the binary and ternary extraction systems were also determined. Both the binary and ternary extraction systems were found to be highly spontaneous processes with predominant enthalpy stabilization. The very high negative entropy factor suggested contribution of unfavourable steric factors.

Anomalous magneto-transport behaviour near the first order phase transition in Gd(5)Ge(3.8)Ga(0.2) alloy

We study the effect of Ga doping at the Ge site of the metamagnetic compound Gd(5)Ge(4). For 5% Ga doping, the resulting alloy (Gd(5)Ge(3.8)Ga(0.2)) shows antiferromagnetic ordering around 130 K, and a thermally driven first order magneto-structural transition at low temperature leading to the ferromagnetic ground state. The alloy shows a noticeable amount of training effect in resistivity when thermally cycled through this first order phase transition (FOPT). The training effect is present in the case of isothermal field cycling. The FOPT region is found to be metastable and extremely sensitive to the applied magnetic field with a clear signature of a metamagnetic transition in the magnetization and resistivity. The metastability is further supported by the large relaxation observed in the resistivity. The giant magnetoresistance observed in the sample is found to be positive near the FOPT, while below the transition it is negative. The resistivity shows irreversibility due to field cycling, which is related to both a field-induced arrested state and some permanent micro-structural changes in the sample.

Cadmium induces lung inflammation independent of lung cell proliferation: a molecular approach

BACKGROUND

Cadmium is one of the inflammation-related xenobiotics and has been regarded as a potent carcinogen. The relationship between inflammation and cell proliferation due to chronic infection has been studied, but the mechanism is not fully clear. Though the mode of cadmium toxicity is well characterized in animal cells, still it requires some further investigations. Previously we reported that cadmium induces immune cell death in Swiss albino mice. In the present study we showed that instead of inducing cell death mechanism, cadmium in low concentration triggers proliferation in mice lung cell and our results reveals that prior to the induction of proliferation it causes severe inflammation.

METHODS

Swiss albino mice were treated with different concentrations of cadmium to determine the LD50. Mice were subdivided (5 mice each) according to the exposure period (15, 30, 45, 60 days) and were given sub lethal dose (5 mg/Kg body weight) of cadmium chloride and ibuprofen (50 mg/Kg body weight, recommended dose) once in a week. SEM and histology were performed as evidence of changes in cellular morphology. Inflammation was measured by the expression of Cox-2 and MMPs. Expression of proinflammatory cytokines (Cox-2, IL-6), signaling and cell cycle regulatory molecules (STAT3, Akt, CyclinD1) were measured by western blot, ELISA and immunoprecipitation. Mutagenecity was evidenced by comet assay. Cell proliferation was determined by cell count, cell cycle and DNA analysis.

RESULTS

Prolonged exposure of low concentration of cadmium resulted in up regulation of proinflammatory cytokines and cell cycle regulatory molecules. Though NSAIDs like Ibuprofen reduces the expression of inflammatory cytokines, but it did not show any inhibitory effect on cadmium adopted lung cell proliferation.

CONCLUSION

Our results prove that cadmium causes both inflammation and cell proliferation when applied in a low dose but proliferative changes occur independent of inflammation.

Divergence to apoptosis from ROS induced cell cycle arrest: effect of cadmium

Recently, the role of cadmium (Cd) in immunosupression has gained importance. Nevertheless, the signaling pathways underlying cadmium-induced immune cell death remains largely unclear. In accordance to our previous in vivo report, and to evaluate the further details of the mechanism, we have investigated the effects of cadmium (CdCl(2), H(2)O) on cell cycle regulation and apoptosis in splenocytes in vitro. Our results have revealed that reactive oxygen species (ROS) and p21 are involved in cell cycle arrest in a p53 independent manner but late hour apoptotic response was accompanied by the p53 up-regulation, loss of mitochondrial transmembrane potential (MTP), down-regulation of Bcl-xl, activation of caspase-3 and release of cytochrome c (Cyt c). However, pifithrin alfa (PFT-alpha), an inhibitor of p53, fails to rescue the cells from the cadmium-induced cell cycle arrest but prevents Bcl-xl down-regulation and loss of Deltapsi(m), which indicates that there is an involvement of p53 in apoptosis. In contrast, treatment with N-acetyl cysteine (NAC) can prevent cell cycle arrest and p21 up-regulation at early hours. Although it is clear that, NAC has no effect on apoptosis, p53 expression and MPT changes at late stage events. Taken together, we have demonstrated that cadmium promotes ROS generation, which potently initiates the cell cycle arrest at early hours and finally induces p53-dependent apoptosis at later part of the event.

Purification and biochemical characterization of a serine proteinase inhibitor from Derris trifoliata Lour. seeds: insight into structural and antimalarial features

A potent serine proteinase inhibitor was isolated and characterized from the seeds of the tropical legume liana, Derris trifoliata (DtTCI) by ammonium sulfate precipitation, ion exchange chromatography and gel filtration chromatography. SDS-PAGE as well as MALDI-TOF analysis showed that DtTCI is a single polypeptide chain with a molecular mass of approximately 20 kDa. DtTCI has three isoinhibitors (pI: 4.55, 5.34 and 5.72) and, inhibited both trypsin and chymotrypsin in a 1:1 molar ratio. Both Dixon plots and Lineweaver-Burk double reciprocal plots revealed a competitive inhibition of trypsin and chymotrypsin activity, with inhibition constants (K(i)) of 1.7x10(-10) and 1.25x10(-10) M, respectively. N-terminal sequence of DtTCI showed over 50% similarity with numerous Kunitz-type inhibitors of the Papilionoideae subfamily. High pH amplitude and broad temperature optima were noted for DtTCI, and time course experiments indicated a gradual loss in inhibitory potency on treatment with dithiothreitol (DTT). Circular Dichroism (CD) spectrum of native DtTCI revealed an unordered structure whereas exposure to thermal-pH extremes, DTT and guanidine hydrochloride (Gdn HCl) suggested that an abundance of beta-sheets along with intramolecular disulfide bonds provide conformational stability to the active site of DtTCI, and that severity of denaturants cause structural modifications promoting inhibitory inactivity. Antimalarial studies of DtTCI indicate it to be a potent antiparasitic agent.

Dark after cholecystectomy

We report a patient who complained of becoming darker after an abdominal surgery. The index patient not only had a darker complexion after cholecystectomy, but his glycaemic control was also getting better after operation to the extent that he could stop insulin, which he had been taking for five years. Also, he had lost significant weight after operation. Later, we found that he had developed primary hypocortisolism due to unrecognized bilateral adrenal haemorrhage in the immediate postoperative period.

Design and testing of a disposable microfluidic chemiluminescent immunoassay for disease biomarkers in human serum samples

This paper presents the development of a plastic microfluidic immunosensor for rapid, reliable and on-the-spot detection of disease biomarkers in human sera. The microfluidic chips were fabricated in cyclic polyolefin by hot-embossing with a silicon master mold. The master itself was made using photolithographic techniques and Deep Reactive Ion Etching (DRIE). As a platform model, serum concentrations of C-reactive protein (CRP), a cardiac and inflammation marker, was measured on-chip using chemiluminescence based immunoassay. The assay results were read via an on-board instant photographic film, and with an imager capable of detecting chemiluminescent signals. The on-board detection module obviates the need for any dedicated bench-top analyzer for reading the immunoassay results, and therefore makes the device self-sufficient for point-of-care diagnostics when simple positive/negative results are sought. The microfluidic chemiluminescence results were compared with standard microplate ELISA analysis to assess the accuracy of the developed microfluidic immunoassay. Screening of CRP in human serum samples showed good correlation with ELISA analysis and the mean difference between the two methods using the Bland and Altman method was -0.079 +/- 0.858 mg/L for hsCRP. With approximate assay times of 25 min, the developed microfluidic immunoassay approach shows great potential for rapid plus sensitive detection of disease markers at the point-of-care.

Bioinsecticidal activity of Archidendron ellipticum trypsin inhibitor on growth and serine digestive enzymes during larval development of Spodoptera litura

The roles of serine proteases involved in the digestion mechanism of the cutworm Spodoptera litura (Lepidoptera: Noctuidae) were examined (in vitro and in vivo) following feeding of plant protease inhibitors. A trypsin inhibitor from Archidendron ellipticum (AeTI) was purified by ammonium sulfate fractionation, ion-exchange chromatography and size-exclusion chromatography (HPLC) and its bioinsecticidal properties against S. litura were compared with Soybean Kunitz trypsin inhibitor (SBTI). AeTI inhibited the trypsin-like activities of the midgut proteases of fifth instar larvae of S. litura by over 70%. Dixon plot analysis revealed competitive inhibition of larval midgut trypsin and chymotrypsin by AeTI, with an inhibition constant (K(i)) of 3.5x10(-9) M and 1.5x10(-9) M, respectively. However, inhibitor kinetics using double reciprocal plots for both trypsin and chymotrypsin inhibitions demonstrated a mixed inhibition pattern. Feeding experiments conducted on different (neonate to ultimate) instars suggested a dose-dependent decrease for both the larval body weight as well as % survival of larva fed on diet containing 50, 100 and 150 microM AeTI. Influence of AeTI on the larval gut physiology indicated a 7-fold decrease of trypsin-like protease activity and a 5-fold increase of chymotrypsin-like protease activity, after being fed with a diet supplemented with 150 microM AeTI. This study suggests that although the early (1st to 3rd) larval instars of S. litura are susceptible to the trypsin inhibitory action of AeTI, the later instars may facilitate the development of new serine proteases, insensitive to the inhibitor.

A trypsin and chymotrypsin inhibitor from Caesalpinia bonduc seeds: isolation, partial characterization and insecticidal properties

Evolution of proteinase inhibitor diversity in leguminous plants of tropical rainforests is under immense pressure from the regular upregulation of proteolytic machinery of their pests. The present study illustrates the isolation and bioinsecticidal potency of a serine proteinase inhibitor from the seeds of Caesalpinia bonduc (CbTI), inhabiting Great Nicobar Island, India. Following initial fractionation by ammonium sulfate precipitation, CbTI was purified to homogeneity by ion exchange, gel filtration and trypsin affinity chromatography. SDS-PAGE of gel filtrated CbTI showed a couple of proteins CbTI-1 ( approximately 16kDa) and CbTI-2 (20kDa) under non-reducing conditions, which subsequent to trypsin affinity chromatography yielded only CbTI-2. Both Native PAGE as well as iso-electric focusing showed 2 iso-inhibitors of CbTI-2 (pI values of 5.35 and 4.6). CbTI exhibited tolerance to extremes of temperatures (0-60 degrees C) and pH (1-12). A 1:1 stoichiometric ratio was noted during CbTI-2-trypsin complex formation, which was absent on binding with chymotrypsin. Further, SDS-PAGE analysis also showed that CbTI-1 has affinity only towards chymotrypsin, whereas both trypsin and chymotrypsin formed complexes with CbTI-2. Dixon plot analysis of CbTI-2 yielded inhibition constants (K(i)) of 2.75 x 10(-10)M and 0.95 x 10(-10)M against trypsin and chymotrypsin activity respectively. Preliminary investigations on the toxicological nature of CbTI revealed it to be a promising bioinsecticidal candidate.