Synthetic investigations on testerone and its analogues—I *1: The total synthesis of 8-isotestosterone and its anthracene analogue

The total synthesis of 8-isotestosterone (II) and the corresponding anthracene analogue (III) following the benzohydrindane route is reported. Catalytic hydrogenation of trans-1β-acetoxy-8-methyl-4,5-(3′-methyl-4′-hydroxybenzo)-hydrindane (V) followed by oxidation has furnished two isomeric tricyclic keto acetates, viz. 1β,2α-(3′-acetoxycyclopentano)-2,5-dimethyl-6-keto-1α,2,3,4,4aα,-5α,6,7,8,8aα-decahydronaphthalene (VII) and 1β,2α-(3′-acetoxycyclopentano)-2,5-dimethyl-6-keto-1α,2,3,4,4aβ,5,6,7,8,8aβ-decahydronaphthalene (IX) which are cis-non-steroid and cis-steroid configurations of the same cyclopentano-cis-decalins. A difference in the direction of enolization of the keto acetate (VII) in alkylation reaction and enol acetylation towards the methine and the methylene carbon atoms respectively has been observed.

Anthranilic acid oxidase system of Tecoma stans—II. : Studies on the properties of a purified anthranilic acid oxidase system and its separation into different enzymic components

An enzyme system which catalysed the conversion of anthranilic acid to catechol has been purified 20-fold from a cell-free leaf extract of Tecoma stans. The optimum substrate concentration was 10−3 M and optimum temperature for the reaction was 45°. The presence of a multi-enzyme system was inferred from inhibition studies. The formation of catechol was inhibited by Mg2+, Zn2+, and Co2+ ions, whereas anthranilic acid disappearance was not affected to the same extent. The effect of metal chelating agents like EDTA, cyanide and pyrophosphate showed a similar trend. PCMB inhibited catechol formation but had no effect on anthranilic acid disappearance. The reaction was not inhibited by catalase, nor was it activated by peroxide-donating systems. This ruled out the possibility of peroxidative type of reaction. The overall reaction is markedly activated by NADPH and THFA. This multi-enzyme was separated into three different components, by fractionation with Alumina Cγ and calcium phosphate gels. The overall reaction catalysed by these components can be represented as anthranilic acid→3-hydroxy anthranilic acid→o-aminophenol→catechol.

Thermal conductivity of liquids and its temperature dependence

The temperature dependence of thermal conductivity of liquids as given by Horrocks and McLaughlin is re-examined and useful relations to estimate thermal conductivity are presented. In the case of the 12 homologous series considered the maximum deviation is about 5%.

Action of N-bromosuccinimide on human hemoglobin and its possible bearing on heme-globin linkage

A reaction of N-bromosuccinimide with the heme groups of hemoglobin has been studied spectrophotometrically. The reaction brings about the disappearance of characteristic absorption peaks of hemoglobin and is accompanied by the release of inorganic iron from the heme groups. Urea is obligatory for the reaction to take place at pH 4.0, while it can occur in the absence of urea at pH 7.0. The spectrum of hemoglobin which does not show any peak in the Soret region at pH 4.0 is “normalized” in the presence of urea or sucrose at the same pH. The effect of “normalization” in 8 M urea is apparent over the pH range 3.0–4.5. From the obligatory requirement of urea and sucrose for “normalization” of spectrum and the dependence of the release of inorganic iron on the concentration of urea, it is suggested that heme groups are “buried” within the globin at pH 4.0 and not dissociated from globin as supposed before.

Polypyrimidine tract-binding protein interacts with coxsackievirus B3 RNA and influences its translation

We have investigated the possible role of trans-acting factors interacting with the untranslated regions (UTRs) of coxsackievirus B3 (CVB3) RNA. We show here that polypyrimidine tract-binding protein (PTB) binds specifically to both 5' and 3' UTRs, but with different affinity. We have demonstrated that PTB is a bona fide internal ribosome entry site (IRES) trans-acting factor (ITAF) for CVB3 RNA by characterizing the effect of partial silencing of FIB ex vivo in He La cells. Furthermore, IRES activity in BSC-1 cells, which are reported to have a very low level of endogenous FIB, was found to be significantly lower than that in He La cells. Additionally, we have mapped the putative contact points of PTB on the 5' and 3' UTRs by an RNA toe-printing assay. We have shown that the 3' UTR is able to stimulate CVB3 IRES-mediated translation. Interestingly, a deletion of 15 nt at the 5' end or 14 rut at the 3' end of the CVB3 3' UTR reduced the 3' UTR-mediated enhancement of IRES activity ex vivo significantly, and a reduced interaction was shown with PTB. It appears that the FIB protein might help in circularization of the CVB3 RNA by bridging the ends necessary for efficient translation of the viral RNA.

Structure of Ce1-xSnxO2 and its relation to oxygen storage property from first-principles analysis

CeO2-SnO2 solid solution has been reported to possess high oxygen storage/release property which possibly originates from local structural distortion. We have performed first-principles based density functional calculations of Ce1-xSnxO2 structure (x=0, 0.25, 0.5, 1) to understand its structural stability in fluorite in comparison to rutile structure of the other end-member SnO2, and studied the local structural distortion induced by the dopant Sn ion. Analysis of relative energies of fluorite and rutile phases of CeO2, SnO2, and Ce1-xSnxO2 indicates that fluorite structure is the most stable for Ce1-xSnxO2 solid solution. An analysis of local structural distortions reflected in phonon dispersion show that SnO2 in fluorite structure is highly unstable while CeO2 in rutile structure is only weakly unstable. Thus, Sn in Ce1-xSnxO2-fluorite structure is associated with high local structural distortion whereas Ce in Ce1-xSnxO2-rutile structure, if formed, will show only marginal local distortion. Determination of M-O (M=Ce or Sn) bond lengths and analysis of Born effective charges for the optimized structure of Ce1-xSnxO2 show that local coordination of these cations changes from ideal eightfold coordination expected of fluorite lattice to 4+4 coordination, leading to generation of long and short Ce-O and Sn-O bonds in the doped structure. Bond valence analyses for all ions show the presence of oxygen with bond valence similar to 1.84. These weakly bonded oxygen ions are relevant for enhanced oxygen storage/release properties observed in Ce1-xSnxO2 solid solution. (C) 2010 American Institute of Physics.

The interaction of glycoxylate with cysteine and its application to the assay of isocitritase and of transaminases involving glyoxylate

An interesting interaction between glyoxylate and cystein takes place in phosphate buffer (pH 7.0) to form a product which is resistant to hydrolysis at ordinary temperatures. The reaction product is broken up by acid hydrolysis at elevated temperatures under controlled conditions, giving a quantitive yield of glyoxylate. Other keto acids, such as α-ketoglutarate, pyruvate and oxaloacetate, do not interact with cysteine under similar conditions. Methods based on these findings are described for(a) direct estimation of other keto acids in the presence of glyoxylate, and (b) assay of isocitritase and glyoxylate transaminase.

Interaction of heterocyclic thiols/thiones eliminated from cephalosporins with iodine and its biological implications

Hydrolysis of beta-lactam antibiotics by beta-lactamases (e. g., metallo-beta-lactamase, m beta l) is one of the major bacterial defense systems. These enzymes can catalyze the hydrolysis of a variety of antibiotics including the latest generation of cephalosporins, cephamycins and imipenem. It is shown in this paper that the thiol/thione moieties eliminated from certain cephalosporins by m beta l-mediated hydrolysis readily react with molecular iodine to produce ionic compounds having S-I bonds. While the reaction of MTT with iodine produced the corresponding disulfide, MDT and DMETT produced the charge-transfer complexes MDT-I-2 and DMETT-I-2, respectively. Addition of two equivalents of I-2 to MDT produced a novel cationic complex having an almost linear S-I+-S moiety and I-5(-) counter anion.However, this reaction appears to be highly solvent dependent. When the reaction of MDT with I2 was carried out in water, the reaction produced a monocation having I-5(-), indicating the reactivity of MDT toward I2 is very similar to that of the most commonly used antithyroid drug methimazole (MMI). In contrast to MMI, MDT and DMETT, the triazine-based compound MTDT acts as a weak donor toward iodine. (C)2010 Elsevier Ltd. All rights reserved.

Lightning-Induced Current and Voltage on a Rocket in the Presence of Its Trailing Exhaust Plume

This paper presents time-domain characteristics of induced current and voltage on a rocket in the presence of its exhaust plume when an electromagnetic (EM) wave generated by a nearby lightning discharge is incident on it. For the EM-field interaction with the rocket, the finite-difference time-domain technique has been used. The distributed electrical parameters, such as capacitance and inductance of the rocket and its exhaust plume, are computed using the method of moments technique. For the electrical characterization of the exhaust plume, the computational fluid dynamics technique has been used. The computed peak value of the electrical conductivity of the exhaust plume is 0.12 S/m near the exit plane and it reduces to 0.02 S/m at the downstream end. The relative permittivity varies from 0.91 to 0.99. The exhaust plume behaves as a good conductor for EM fields with frequencies less than 2.285 GHz. It has been observed that the peak value of the induced current on the rocket gets enhanced significantly in the presence of the conducting exhaust plume for the rocket and exhaust plume dimensions and parameters studied. The magnitude of the time-varying induced current at the tail is much more than that of any other section of the rocket.

Lightning-Induced Current and Voltage on a Rocket in the Presence of Its Trailing Exhaust Plume

This paper presents time-domain characteristics of induced current and voltage on a rocket in the presence of its exhaust plume when an electromagnetic (EM) wave generated by a nearby lightning discharge is incident on it. For the EM-field interaction with the rocket, the finite-difference time-domain technique has been used. The distributed electrical parameters, such as capacitance and inductance of the rocket and its exhaust plume, are computed using the method of moments technique. For the electrical characterization of the exhaust plume, the computational fluid dynamics technique has been used. The computed peak value of the electrical conductivity of the exhaust plume is 0.12 S/m near the exit plane and it reduces to 0.02 S/m at the downstream end. The relative permittivity varies from 0.91 to 0.99. The exhaust plume behaves as a good conductor for EM fields with frequencies less than 2.285 GHz. It has been observed that the peak value of the induced current on the rocket gets enhanced significantly in the presence of the conducting exhaust plume for the rocket and exhaust plume dimensions and parameters studied. The magnitude of the time-varying induced current at the tail is much more than that of any other section of the rocket.

The heat kernel on AdS(3) and its applications

We derive the heat kernel for arbitrary tensor fields on S-3 and (Euclidean) AdS(3) using a group theoretic approach. We use these results to also obtain the heat kernel on certain quotients of these spaces. In particular, we give a simple, explicit expression for the one loop determinant for a field of arbitrary spin s in thermal AdS(3). We apply this to the calculation of the one loop partition function of N = 1 supergravity on AdS(3). We find that the answer factorizes into left- and right-moving super Virasoro characters built on the SL(2, C) invariant vacuum, as argued by Maloney and Witten on general grounds.

Differential synthesis of proteins by T4 phage and its head protein amber mutant

There was no difference in the incorporation of S-35 label into proteins of T4 and amber B17 phage grown on Escherichia coli B. The head protein peak was absent in the polyacrylamide gel electrophoretic profile of the S-35 labeled proteins of amber B17 grown on non-permissive host, E.coli B. However, an increase of 15–70% in the synthesis of other phage proteins of amber B17 over that of T4 phage was observed. The lysozyme activity increased by two fold in amber B17 in comparison with that of T4 phage grown on E.coli B. These results imply that in the absence of head protein synthesis by amber mutant there was an increase in the synthesis of other phage proteins.

ErbB-2 expression and its association with other biological parameters of breast cancer among Indian women

Overexpression of the epidermal growth factor receptor family genes, which include ErbB-1, 2, 3 and 4, has been implicated in a number of cancers. We have studied the extent of ErbB-2 overexpression among Indian women with sporadic breast cancer. Methods: Immmunohistochemistry and genomic polymerase chain reaction (PCR) were used to study the ErbB2 overexpression. ErbB2 status was correlated with other clinico-pathological parameters, including patient survival. Results: ErbB-2 overexpression was detected in 43.2% (159/368) of the cases by immunohistochemistry. For a sub-set of patients (n = 55) for whom total DNA was available, ErbB-2 gene amplification was detected in 25.5% (14/55) of the cases by genomic PCR. While the ErbB2 overexpression was significantly higher in patients with lymphnode (χ2 = 12.06, P≤ 0.001), larger tumor size (χ2 = 8.22, P = 0.042) and ductal carcinoma (χ2 = 15.42, P ≤ 0.001), it was lower in patients with disease-free survival (χ2 = 22.13, P ≤ 0.001). Survival analysis on a sub-set of patients for whom survival data were available (n = 179) revealed that ErbB-2 status (χ2 =25.94, P ≤ 0.001), lymphnode status (χ2 = 12.68, P ≤ 0.001), distant metastasis (χ2 = 19.49, P ≤ 0.001) and stage of the disease (χ2 = 28.04, P ≤0.001) were markers of poor prognosis. Conclusions: ErbB-2 overexpression was significantly greater compared with the Western literature, but comparable to other Indian studies. Significant correlation was found between ErbB-2 status and lymphnode status, tumor size and ductal carcinoma. ErbB-2 status, lymph node status, distant metastasis and stage of the disease were found to be prognostic indicators.