Effect of specific FSH or LH deprivation on testicular function of the adult rat

While the need for FSH in initiating spermatogenesis in the immature rat is well accepted, its requirement for maintenance of spermatogenesis in adulthood is questioned. In the current study, using gonadotropin antisera to neutralize specifically either endogenous FSH or LH, we have investigated the effect of either FSH or LH deprivation for a 10-day period on (i) testicular macromolecular synthesis in vitro, (ii) the activities of testicular germ cell specific LDH-X and hyaluronidase enzymes, and finally (iii) on the concentration of sulphated glycoprotein (SGP-2), one of the Sertoli cell marker proteins. Both immature (35-day-old) and adult (100-day-old) rats have been used in this study. Since LH deprivation leads to a near total blockade of testosterone production, the ability of exogenous testosterone supplementation to override the effects of LH deficiency has also been evaluated. Deprivation of either of the gonadotropins significantly affected in vitro RNA and protein synthesis by both testicular minces as well as single cell preparations. Fractionation of dispersed testicular cells preincubated with labelled precursors of RNA and protein on Percoll density gradient revealed that FSH deprivation affected specifically the rate of RNA and protein synthesis of germ cell and not Leydig cell fraction. LH but not FSH deprivation inhibited [3H]thymidine incorporation into DNA. The inhibitory effect of LH could mostly be overriden by testosterone supplementation. LDH-X and hyaluronidase activities of testicular homogenates of adult rats showed significant reduction (50%; P less than .05) following either FSH or LH deprivation. Again testosterone supplementation was able to reverse the LH inhibitory effect.

Thermal expansion of doped lanthanum gallates

Thermal expansion of several compositions of Sr and Mg-doped LaGaO3 including an A-site deficient composition (La0.9Sr0.1)(0.98)(Ga0.8Mg0.2)O-2.821 were measured in the temperature range from 298 to 1273 K. The effect of doping on thermal expansion was studied by varying the composition at one site of the perovskite structure (either A or B), while keeping the composition at the other site invariant. Thermal expansion varied nonlinearly with temperature and exhibited an inflexion between 550 and 620 K, probably related to the change in crystal structure from orthorhombic to rhombohedral. The dependence of average thermal expansion coefficient (alpha (av)) on the dopant concentration on either A or B site of the perovskite structure was found to be linear, when the composition at the other site was kept constant. Mg doping on the B-site had a greater effect on the average thermal expansion coefficient than Sr doping on the A-site. Cation deficiency at the A-site decreases thermal expansion when compositions at both sites are held constant.

Second harmonic generation in some donor-acceptor ethylenes—I

We report the absorption spectra, oscillator strengths, ground state and excited state dipole moments, and molecular second order polarizability coefficients (βCT) due to donor—acceptor charge transfer in four trisubstituted ethylenes, namely 1,1-bisdimethylamino-2-nitroethylene, 1,1-bispyrolidino-2-nitroethylene, 1,1-bispiperidino-2-nitroethylene and 1,1-bismorpholino-2-nitroethylene. The results are compared with that of trans-N,N-dimethylamino-nitroethylene, which has a large βCT. The powder second harmonic generation (SHG) intensity of all these molecules is also measured and only 1,1-bispiperidino-2-nitroethylene is found to possess an efficiency of 20% of that of urea under the same conditions. The SHG efficiency of this compound and deficiency in the other molecules in the powdered state is discussed in terms of their arrangements in the unit cell. The crystal structure of the active molecule is also presented and the structure—property relationship is critically examined in all these molecules.

Consistency limits behavior of bentonites exposed to sea water

This article examines the changes in interparticle forces brought about on prolonged contact (1 year period) of a bentonite clay with artificial seawater. The study is undertaken with the purpose of identifying the physico-chemical factors that impart a nonswelling character to smectite clays deposited in marine environments. Results show that equilibration of the bentonite clay with artificial seawater (total pore salinity approximately 42 gL-1) for a 1 year period does not lead to any mineralogical changes in the clay specimens; however, their exchangeable cation positions become prominently dominated by magnesium ions. The consistency limits of the seawater-equilibrated bentonite was determined on stepwise leaching to lower salinities. The predominance of diffuse double-layer repulsion forces in the pore salt concentration range of 42 gL-1 to 1.1 gL-1 caused an increase in the liquid limits of the seawater-equilibrated bentonite specimens on reducing the salinity in the corresponding range (42 gL-1 to 1.1 gL-1). The attraction forces, however, prevail over the repulsion forces at salt concentrations <1.1 gL-1 and cause a decrease in liquid limit of the clay specimens with reduction in pore salinity, which is typical of nonswelling clays. The attraction forces cause aggregation of the clay unit layers into domains that break down on sodium saturation of the clay specimens. It is inferred that the physico-chemical factors responsible for the nonswelling character of the seawater-equilibrated bentonite specimens at pore salt concentrations below 1.1 gL-1 are inadequate to explain the nonswelling character of smectite-rich Ariake marine clays. The lower consistency limits of the Ariake marine clays in comparison to the nonswelling character, seawater-equilibrated bentonite specimens is attributed to a relative deficiency of interparticle forces in the Ariake marine clay.

Flap‐Lag Damping in Hover and Forward Flight with a Three‐Dimensional Wake

Prediction of lag damping is difficult owing to the delicate balance of drag, induced drag and Coriolis forces in the in‐plane direction. Moreover, induced drag” is sensitive to dynamic wake, bath shed and trailing components, and thus its prediction requires adequate unsteady‐wake representation. Accordingly, rigid‐blade flap‐lag equations are coupled with a three‐dimensional finite‐state wake model; three isolatcd rotor canfigurations with three, four and five blades are treated over a range of thrust levels, tack numbers, lag frequencies and advance ratios. The investigation includes convergence characteristics of damping with respect to the number of radial shape functions and harmonics of the wake model for multiblade modes of low frequency (< 1/ rev.) to high frequency (> 1/rev.). Predicted flap and lag damping levels are then compared with similar predictions with 1) rigid wake (no unsteady induced now), 2) Loewy lift deficiency and 3) dynamic inflow. The coverage also includes correlations with the measured lag regressive‐mode damping in hover and forward flight and comparisons with similar correlations with dynamic inflow. Lag‐damping predictions with the dynamic wake model are consistently higher than the predictions with the dynamic inflow model; even for the low frequency lag regressive mode, the number of wake harmonics should at least be equal to twice the number of blades.

Characterization of a variant glucose-6-phosphate dehydrogenase from the south Indian population.

Glucose-6-phosphate dehydrogenase (G6PD) is coded by a gene on the X-chromosome. Earlier studies have shown that the South Indian population has a high incidence of this enzyme deficiency. The electrophoretic mobility, pH optimum and the K-m values for G6PD from normal and variant individuals were identical. However, the specific activity of the variant enzyme was 8 times less compared to the value of the normal enzyme. Western blot analysis of partially purified G6PD from normal and variant individuals performed using equal amounts of total protein showed that the variant protein was 3 times less in concentration. Similar analysis performed using protein corresponding to equal enzyme activity units in the normal and variant samples showed that the variant enzyme was 2.25 times less efficient compared to the normal enzyme. RNA dot blot analysis using full length G6PD cDNA probe (PGDT5B, a kind gift from Prof. L Luzzatto) revealed that lymphocytes from normal and variant individuals had equal amounts of G6PD specific mRNA.

Effect of sodium diffusion on the structural and electrical properties of Cu2ZnSnS4 thin films

Cu2ZnSnS4 (CZTS) is a kesterite semiconductor consisting of abundantly available elements. It has a band gap of 1.5 eV and a large absorption coefficient. Hence, thin films made of this material can be used as absorber layers of a solar cell. CZTS films were deposited on soda lime and Na free borosilicate glass substrates through Ultrasonic Spray Pyrolysis. The diffusion of sodium from soda lime glass was found to have a profound effect on characteristics like grain size, crystal texture and conductivity of CZTS thin films. Copper ion concentration also varied during the deposition and it was observed that the carrier concentration was enhanced when there was a deficiency of copper in the films. The effect of sodium diffusion and copper deficiency in enhancing the structural and electrical properties of CZTS films are presented in this paper. (C) 2010 Elsevier B.V. All rights reserved.

Anomalin. A Dihydropyranocoumarin Derivative from the Plant Lingusticum elatum

The title compound, 9,10-dihydro-8,8-dimethyl-2-oxo-2H,8H-benzo[1,2-b:3,4-b']dipyran-9,10-diyl 2-methyl-2-butenoate, C24H26O7, contains a highly planar coumarin nucleus and a substituted dihydropyran ring (C), which has a distorted half-chair conformation, with an 8 alpha,9 beta orientation. The conformation of ring C is further supported by the two angelyloxy (2-methyl-2-butenoyloxy) substituents at positions C9 and C10, which are cis oriented and thus cannot both occupy equatorial positions with respect to the plane of ring C. The conformations of the two angelyloxy substituents are different, as indicated by their endocyclic torsion angles. The most striking of these angles are O1'-C2'-C4'=C6' and O1'-C2'-C4'-C5' [-137.7 (5) and 43.7 (5)degrees, respectively, in the chain at C10 and 155.8 (5) and -24.7 (9)degrees, respectively in the chain at C9]. These variations are due to two intramolecular hydrogen bonds, namely, C16-H161 ... O1' [C16 ... O1' 3.056 (7) Angstrom] and C7''-H7Y ... O3'' [C7'' ... O3'' 2.955 (12) Angstrom]. The methyl substituents, C15 and C16, at position C8 are alpha and beta oriented, respectively. The crystal structure is stabilized by a weak C4-H41 ... O3' hydrogen bond [C4 ... O3' 3.297 (6) Angstrom] between the screw-related molecules.

Analysis of geometric and strain effects in homo-Diels-Alder reactions

Molecular mechanics calculations have been carried out to quantify the key geometric and strain effects which are likely to control the homo-Diels-Alder reactivity of 1,4-dienes. The criteria considered include C1..C5 and C2..C4 distances in the diene, twist angle of the two pi units, and the magnitude of strain increase as a result of cycloaddition. By first considering these factors in a number of non-conjugated dienes with known reactivity, the ranges of values within which the reaction is favoured are proposed. Calculations are also reported on several substrates which have not been investigated so far. Promising systems for experimental study are suggested which, in addition to being intrinsically interesting, would place the present proposals on a firm basis.

N-3-benzoyl-2 ',3 '-di-O-benzoyluridine

The structure of N-3-benzoyl-2',3'-di-O-benzoyluridine, C30H24N2O9, has two molecules in the asymmetric unit. The uracil bases of both the molecules are in the anti conformation with respect to the ribose moiety and the furanosyl rings adopt a C3'-endo conformation. The orientation about the C4'-C5' bond is gauche-gauche. The two crystallographically independent molecules are linked through several C-H ... O hydrogen bonds. The nucleoside molecules pack as columns along the a axis and these columns repeat along the c axis.

N-4-anisoylcytidine dihydrate

The title compound, C17H19N3O7. 2H(2)O, has C2'-endo, C3'-exo puckering, The orientation of the base with respect to the sugar is anti and the geometry about C4'-C5' is gauche,trans. The angle between the cytidine base and the phenyl ring of the anisoyl group is 15.5(2)degrees.

N-6-anisoyladenosine monohydrate

The title compound, C18H19N5O6. H2O, has a syn conformation about the glycosidic bond. Its furanose ring shows a C2'-endo-C3'-exo twist conformation and trans-gauche geometry about the C4'-C5' bond. The angle between the adenine base and the phenyl ring of the anisoyl group is 22.9 degrees. Adenine and anisoyl groups stack along the b axis at a separation of 3.4 Angstrom.

Structure, function, and mechanism of HhaI DNA methyltransferases

A vast amount of literature has accumulated on the characterization of DNA methyltransferases. The HhaI DNA methyltransferase, a C5-cytosine methyltransferase, has been the subject of investigation for the last 2 decades. Biochemical and kinetic characterization have led to an understanding of the catalytic and kinetic mechanism of the methyltransfer reaction. The HhaI methyltransferase has also been subjected to extensive structural analysis, with the availability of 12 structures with or without a cofactor and a variety of DNA substrates. The mechanism of base flipping, first described for the HhaI methyltransferase, is conserved among all DNA methyltransferases and is also found to occur in numerous DNA repair enzymes. Studies with other methyltransferase reveal a significant structural and functional similarity among different types of methyltransferases. This review aims to summarize the available information on the HhaI DNA methyltransferase.

Structure and Bonding in Stannadiphospholes and their Dianions SnC(2)P(2)R(2)(m) (R=H, tBu m=0,-2): A Comparative Study with C(5)H(5)(+) and C(5)H(5)(-) Analogues

The potential energy surfaces of both neutral and dianionic SnC(2)P(2)R(2) (R=H, tBu) ring systems have been explored at the B3PW91/LANL2DZ (Sn) and 6-311 + G* (other atoms) level. In the neutral isomers the global minimum is a nido structure in which a 1,2-diphosphocyclobutadiene ring (1,2-DPCB) is capped by the Sn. Interestingly, the structure established by Xray diffraction analysis, for R=tBu, is a 1,3-DPCB ring capped by Sn and it is 2.4 kcal mol(-1) higher in energy than the 1,2-DPCB ring isomer. This is possibly related to the kinetic stability of the 1,3-DPCB ring, which might originate from the synthetic precursor ZrCp(2)tBu(2)C(2)P(2). In the case of the dianionic isomers we observe only a 6 pi-electron aromatic structure as the global minimum, similarly to the cases of our previously reported results with other types of heterodiphospholes.([1,4,19]) The existence of large numbers of cluster-type isomers in neutral and 6 pi-planar structures in the dianions SnC(2)P(2)R(2)(2-) (R=H, tBu) is due to 3D aromaticity in neutral clusters and to 2D pi aromaticity of the dianionic rings. Relative energies of positional isomers mainly depend on: 1) the valency and coordination number of the Sn centre, 2) individual bond strengths, and 3) the steric effect of tBu groups. A comparison of neutral stannadiphospholes with other structurally related C(5)H(5)(+) analogues indicates that Sn might be a better isolobal analogue to P(+) than to BH or CH(+). The variation in global minima in these C(5)H(5)(+) analogues is due to characteristic features such as 1) the different valencies of C, B, P and Sn, 2) the electron deficiency of B, 3) weaker p pi-p pi bonding by P and Sn atoms, and 4) the tendency of electropositive elements to donate electrons to nido clusters. Unlike the C5H5+ systems, all C(5)H(5)(-) analogues have 6 pi-planar aromatic structures as global minima. The differences in the relative ordering of the positional isomers and ligating properties are significant and depend on 1) the nature of the pi orbitals involved, and 2) effective overlap of orbitals.

Crystal Structure, Thermal Expansion and ElectricaH Conductivity of Yo.sCao.2Fel-x Mnx03+o (0 < x < 1.0)

The crystal structure, thennal expansion and electrical conductivity of the solid solutions YOgCao.2Fel-x MnxOJ+c5 (0 ~ x ~ 1.0) were investigated. All compositions had the GdFeOrtype orthorhombic perovskite structure with trace amounts of a second phase present in case of x = 0.8 and 1.0. The lattice parameters were detennined at room tempe'rature by using X-ray powder diffraction (XRPD). The pseudocubic lattice constant decreased with increasing x. The average I inear thermal expansion coefficient (anv) in the temperature range from 673 to 973 K showed negligible change with x up to x = 0.4. The thennal expansion curve for x = I had a slope approaching zero in the temperature range from 648 to 948 K. The calculated activation energy values for electrical conduction indicate that conduction occurs primarily by the small polaron hopping mechanism. The drastic drop in electrical conductivity for a small addition of Mn (0 ~ x ~ 0.2) is caused by the preferential fonnation of Mn4t ion~ (rather than Fe4 +) which act as carrier traps. This continues till the charge compensation for the divalent ions on the A-site is complete. The results indicate that with further increase in manganese content (beyond x =0.4) in the solid solutions, there is an increase in exc :::ss oxygen and consequently, a small increase in Mn'll il>I1~, which are charge compensated by the formation of cation vancancies.