Effect of hormone on chromosome behaviour in callus cultures ofAsparagus racemosus

Chromosomal variability in callus culture ofAsparagus racemosus was comparatively higher in the presence of 2,4-D than of NAA. The frequency of polyploid cells was enhanced with the increase in the concentration of 2,4-D or with the addition of coconut water. Gradual polyploidization with increasing age of the callus has been recorded.     

Analyses of sedimentation equilibrium data

A numerical procedure is presented which can quite adequately compute the molecular weight averages as a function of solute concentration from sedimentation equilibrium data for homogeneous systems and for monomer-dimer associating systems with a possible extension to heterogeneous systems where monotonic variation in the weight average molecular weight is observed such as in weakly associating or dissociating systems. The procedure utilizes the method of orthogonal polynomials for curve fitting which allows for a rapid determination of best fit with minimal round off error. The procedure is particularly applicable in cases where the concentration of solute at the meniscus can be considered to be neither appreciable and reasonably well determined as in low speed sedimentation equilibrium experiments, nor essentially zero as in high speed sedimentation equilibrium experiments where the calculations become somewhat more simplified. The use of moderate speed sedimentation equilibrium has the advantage of providing a more broad concentration distribution in the centrifuge cell which yields more extensive information concerning dissociating systems yet still provides results at low solute concentrations where most solutes can be considered to be behaving ideally.     

Effect of estrogen on biochemical composition of the rat seminiferous tubules

This study concerns the effect of graded doses of estrogen, alone or in combinations with progesterone, on the biochemical composition of the rat seminiferous tubules. Data on the accessory genital organs and pituitary gonadotrophic activity are added. Adult male albino rats received estradiol dipropionate (.1, 1 and 5 mcg/rat) injected intramuscularly, in .1 ml olive oil, daily for 30 days. Animals given the 5 mcg dose were given a 30 day rest period to determine reversibility of effects. In another group estrogen (5 mcg/rat) and progesterone (1 mg/rat) were given concurrently but at different sites for 30 days. Controls received vehicle only. Animals were sacrificed 24 hours after the last injection or rest period and genital organs and the pituitary were removed for study. A progessive reduction in testis weight with dosage was found after estrogen or the combination (p is less that .01). The low dose (.1mcg) had an inconsistent effect on spermatogenesis and endocrine function of the testis. Diameter of the tubules was reduced. Spermatogenesis was arrested in 25% of the tubules at the spermatid of secondary spermatocyte stage. Some normal spermatozoa were seen. Tunica propria was thickened. Some Leydig cells showed atrophy. Vascularity was increased. The median dose (1 mcg) caused spermatogenic arrest at the spermatid or secondary spermatocyte stage but the Sertoli cells were prominent. Only a few spermatozoa were seen. There was some desquamation of seminiferous epithilium. Tubular diameter was still further reduced and the tunica propria thickened. Leydig cells were atrophied. Few spermatozoa were found although 25-30% showed some spermatogenesis. The high dose (5 mcg) caused marked reduction in the diameter of the tubules. Spermatogenesis was arrested at the primary spermatocyte or spermatogonial stage. The tunica popria was much thickened. There was much desquamation and tubular lumeus were filled with debris. The Sertoli cells were hypertrophied. The Leydig cells were atrophied. The tunica albuginea was thickened. There were no spermatozoa. In the recovery group estrogen effects had disappeared, but the tubular diameter remained reduced. Tunica propria was normal. Spermatogenesis progressed to the spermatid stage and in 50% of the tubules many spermatozoa were present. The Leydig cells appeared normal. However spermatozoa were not found in the vas defereus. The histological appearance of the teatis in the estrogen and progesterone group was of the high dose estrogen type but with arrest of spermatogenesis at the spermatid, spermatocye or spermatogonial stage. The Sertoli cells remained hypertrophied. Leydig cells were atrophic. The large blood vessels were engorged. Weight of organs returned almost to normal. Estrogen .1 and 1 mcg had no effect on pituitary weight or gonadotrophin content. The high dose (5 mcg) alone or with progesterone caused a significant increase in pituitary weight (p is less than .0). Estrogen alone (5 mcg) caused a significant decline in pituitary gonadotrophin content (p is less than .0) but the combined therapy had no effect. None of the biochemical constituents of the seminiferous tubules showed any change after injection of .1 mcg of estrogen but 1 mcg dose caused an increase in protein nitrogen, alkaline phosphatase activity and total lipids. The high dose (5 mcg) provoked higher levels.     

Synthesis and SAR studies of 1-substituted-n-(4-alkoxycarbonylpiperidin-1-yl)alkanes as potent antiarrhythmic agents.

Synthesis and SAR studies of the title compounds have resulted in the identification of structural and physicochemical parameter (Vw) contributing for antiarrhythmic activity. Among the two most promising compounds 3a & 3b, the 3a has shown antiarrhythmic activity comparable to quinidine.     

Direct Regulation of Osteocytic Connexin 43 Hemichannels through AKT Kinase Activated by Mechanical Stimulation

Connexin (Cx) 43 hemichannels in osteocytes are thought to play a critical role in releasing bone modulators in response to mechanical loading, a process important for bone formation and remodeling. However, the underlying mechanism that regulates the opening of mechanosensitive hemichannels is largely unknown. We have recently shown that Cx43 and integrin α5 interact directly with each other, and activation of PI3K appears to be required for Cx43 hemichannel opening by mechanical stimulation. Here, we show that mechanical loading through fluid flow shear stress (FFSS) increased the level of active AKT, a downstream effector of PI3K, which is correlated with the opening of hemichannels. Both Cx43 and integrin α5 are directly phosphorylated by AKT. Inhibition of AKT activation significantly reduced FFSS-induced opening of hemichannels and disrupted the interaction between Cx43 and integrin α5. Moreover, AKT phosphorylation on Cx43 and integrin α5 enhanced their interaction. In contrast to the C terminus of wild-type Cx43, overexpression of the C-terminal mutant containing S373A, a consensus site previously shown to be phosphorylated by AKT, failed to bind with α5 and hence could not inhibit hemichannel opening. Together, our results suggest that AKT activated by FFSS directly phosphorylates Cx43 and integrin α5, and Ser-373 of Cx43 plays a predominant role in mediating the interaction between these two proteins and Cx43 hemichannel opening, a crucial step to mediate the anabolic function of mechanical loading in the bone.