A new selective agent for poly(tetrahydrofuran) degradation as a tool for the determination of the crystallite core size

The method formerly used to determine the crystallite core size of polyethylene was applied to poly(tetrahydrofuran) (PTHF). This method is based on the different diffusivity of a chaincleaving agent in crystalline and amorphous parts of the polymer. Butyllithium was used as a cleaving agent of PTHF. The degree of polymerization of the undecomposed part of the polymer (PTHF crystallites) was determined by gel permeation chromatography. This value agrees well with the value to be expected from the size of the crystallites determined small-angle X-ray scattering.     

Polycondensation-addition. V. Polyurethan-ureas with asymmetric carbon atoms in the main chain from L- and DL-2-alkyl-2-isocyanatoethyl chloroformates and diamines1

L - and DL-2-Alkyl-2-isocyanatoethyl chloroformates were synthesized by the phosgenation of the corresponding amino alcohols. These optically active or racemic difunctional compounds were submitted to polycondensation-addition with various diamines to form high molecular weight polyurethan-ureas having asymmetric carbon atoms along the main chain. The optically active polyurethan-ureas obtained had slightly higher melting points than the corresponding racemic polymers.     

Nature and significance of calcium oxalate crystals in normal human thyroid gland

To elucidate the significance and nature of calcium oxalate crystals in the thyroid, we studied these crystals clinicopathologically and immunohistochemically in 182 normal thyroids from patients autopsied within 5 h of death. Under polarized light, calcium oxalate crystals showed brilliant birefringence and were invariably found within the colloid. The crystals were found in 73.1% of all cases but were more prevalent and denser in older individuals, with the highest prevalence (85.2%) being observed in those over 70 years of age. No crystals were seen in those under 10 years of age. Although underlying diseases seemed to have little influence, post-mortem delay apparently affected the prevalence and density of occurrence since the crystals tended to disappear with hours after death. An immunohistochemical study using anti-thyroid hormone antibodies revealed that the crystals were within negatively or weakly stained colloid and were not common in strongly stained colloid. These findings support the hypothesis that the occurrence of calcium oxalate crystals in normal human thyroid is associated with a low functional state of the thyroid follicles.     

Modifying effects of 1'-acetoxychavicol acetate (ACA) and the novel synthetic retinoids Re-80, Am-580 and Am-55P in a two-stage carcinogenesis model in female rats

Effects of dietary administration of 1'-acetoxychavicol acetate (ACA) and the novel synthetic retinoids 4-[1-hydroxy-3-oxo-3-(5,6,7,8-tetrahydro-3-hydroxy-5,5,8,8-tetramethyl-2-naphthalenyl)-1-propenyl]benzoic acid (Re-80); 4-[(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthalenyl)carboxamido]benzoic acid (Am-580); and 6-[(3,5-di-tert-butylphenyl) carbamoyl]nicotinic acid (Am-55P) were examined using a two-stage rat carcinogenesis model. A total of 190 female SD rats was treated sequentially with 1,2-dimethylhydrazine (DMH, s.c.); 7,12-dimethylbenz(a)anthracene (DMBA, i.g.); and 2,2'-dihydroxy-di-n-propylnitrosamine (DHPN, in the drinking water) during the first three weeks (DDD-initiation), and an additional 60 rats received the vehicle alone (non-initiation). One week after the completion of the initiation period, they were divided into nine groups and administrated Re-80 (at dose levels of 1.0 or 0.4 ppm), Am-580 (20 or 4 ppm), Am-55P (20 ppm), ACA (100 ppm), all-trans-retinoic acid (10 or 2 ppm) or no supplement in the diet for 33 weeks, until survivors were euthanatized at week 37 weeks. After DDD-initiation, all-trans-retinoic acid at the high dose delayed the development of mammary tumors. The multiplicity of colon tumors in the group fed Am-55P and the incidences of nephroblastomas with ACA or Am-580 were decreased as compared with the control values, but the other chemicals had no modifying effects on tumor development in any organs. Thus, among ACA and the novel synthetic retinoids tested, only Am-55P showed a weak inhibitory effect on a neoplasm of general interest under the present experimental conditions.     

Involvement of cAMP response element-binding protein activation in salivary secretion.

OBJECTIVE: Saliva secretion is mediated by cAMP and the calcium signaling pathway in salivary acinar cells. The PKA signaling pathway plays an important role in protein secretion through the activation of cAMP, in fluid secretion through the elevation of intracellular calcium and in the activation of cAMP response element-binding protein (CREB), which is involved in these signaling cascades. In this study, we investigated whether the activation of CREB plays a part in the salivary secretion in mice. METHODS: We examined CREB activation by assessing phosphorylation at the serine-133 position using Western blotting. RESULTS: Carbachol (a muscarinic acetylcholine agonist) and isoproterenol (a beta-adrenergic agonist) markedly activated CREB in parotid acinar cells. Carbachol and isoproterenol-induced CREB phosphorylation was blocked by atropine (a muscarinic acetylcholine antagonist) and propranolol (a beta-adrenergic antagonist), respectively. The PKA inhibitor H89 inhibited CREB activation, but the PLC inhibitor U73122 did not. Moreover, carbachol- and isoproterenol-stimulated amylase secretion from parotid acinar cells was inhibited by H89 and adenoviral dominant-negative CREB. CONCLUSION: These results indicate that the muscarinic and beta-adrenergic activation of CREB was mediated through the PKA pathway and that CREB is involved in protein secretion from parotid acinar cells.     

Pseudorandom testing technique for the characterization of local hemodynamic control

Summary In order to investigate the low frequency properties of renal and femoral hemodynamic variables, pseudorandom testing techniques were used. The arterial flow of each bed, in separate experiments, was modulated by a low amplitude signal based on a pseudorandom binary sequence (PRBS) generated by digital computer.The cross-correlation functions between input flow and arterial pressure, venous pressure, and venous flow exhibit damped oscillations in all cases. These responses are parameterized in terms of a damping ratio () and an undamped natural frequency _n for a second order model. The parameters of the model are dependent upon the state of the bed as defined by mean arterial and venous pressures, mean flow through the bed, resistance, and oxygen consumption.The results of this study offer further insight into the dynamic low frequency autoregulation phenomenon for the renal and femoral beds of the dog.Supported by NIH Grant HE 11747.     

The molecular structures of 1,1-diphenylethyl methacrylate and triphenylmethyl methacrylate

The molecular structures of 1,1-diphenylethyl methacrylate (1,1-DPEMA) and triphenylmethyl methacrylate (TrMA) were determined by means of X-ray diffraction. 1,1-DPEMA: monoclinic, space group P2₁/a,a = 9,666(6), b = 19,94(2), c = 8,132(6) Å, β = 104,49(7)°, and Z = 4; TrMA: monoclinic, space group P2₁/n, a = 17,349(3), b = 9,487(2), c = 11,254(2) Å, β = 102,30(2)°, and Z = 4. Both structures were solved by the direct method and refined by the block-diagonal least-squares procedure to R = 0,175 and 0,056 for non-zero reflections, respectively. In both molecules, conformations about the C(1)? C(2) and C(1)? O(1) bonds are all synperiplanar and one of the two or three phenyl groups attached to the C(5) atom is in trans to the O(2).