Circadian rhythms in the incorporation and secretion of 3H-proline by odontoblasts in relation to incremental lines in rat dentin

Circadian incremental lines are universally found in the dentin of animals. They are believed to be caused by functional changes in odontoblasts over 24 hrs. However, the mechanism of rhythmic dentin formation has not yet been elucidated. In the present study, we investigated whether there is a 24-hour rhythm in the collagen-synthetic and secretory activities of odontoblasts by radioautography with 3H-proline as a tracer. Six different groups of rats were injected with 3H-proline at 0000, 0400, 0800, 1200, 1600, or 2000 after the animals had become acclimated to a 12/12-hour light-dark illumination cycle for 2 wks. One hour after the injection, the maxillary incisors were removed and processed for radioautographic study. The silver grains of 3H-proline were most intense over odontoblasts and predentin during the environmental light period, while the nadir occurred during the dark period. The peak value was approximately two-fold higher than the minimum value. Moreover, in the dentin from rats that had been infused with 3H-proline continuously for 10 days by means of osmotic minipumps, silver grains of 3H-proline were heavily distributed over the dark hematoxylin-stained incremental lines. Thus, we demonstrated that odontoblasts show circadian rhythm with regard to collagen synthesis and secretion. These rhythms in odontoblastic function may be responsible for circadian incremental lines in dentin.     

Crossbridge scheme and the kinetic constants of elementary steps deduced from chemically skinned papillary and trabecular muscles of the ferret

Elementary steps of the crossbridge cycle in chemically skinned ferret myocardium were investigated with sinusoidal analysis. The muscle preparations were activated at pCa 4.82 and an ionic strength of 200 mM, and the effects of the change in the MgATP (S) and phosphate (Pi) concentrations on three exponential processes were studied at 20 degrees C. Results are consistent with the following crossbridge scheme: [formula: see text] where A is actin, M is myosin, D is MgADP, and Det includes all detached states (MS and MDP) and weakly attached states (AMS and AMDP). From our studies, we obtained K1a = 0.99 mM-1 (MgATP association), k1b = 270 s-1 (ATP isomerization), k-1b = 280 s-1 (reverse isomerization), K1b = k1b/k-1b = 0.95, k2 = 48 s-1 (crossbridge detachment), k-2 = 14 s-1 (reverse detachment), K2 = 3.5, k4 = 11 s-1 (crossbridge attachment), k-4 = 107 s-1 (reverse attachment), K4 = 0.11, and K5 = 0.06 mM-1 (Pi association). K6 is the rate-limiting step, and it is the slowest forward reaction in the cycle, which results in the rigor-like AM state. K1a (MgATP binding) is four times that of rabbit psoas, and K5 (Pi binding) is 0.3 times that of psoas, demonstrating that crossbridges in myocardium bind MgATP more and Pi less than psoas. The rate constants of ATP isomerization (k1b, k-1b), crossbridge detachment (k2, k-2), and crossbridge attachment (k4) steps are generally an order of magnitude slower than rabbit psoas. The reverse attachment step (k-4) is similar to that in psoas, indicating that this step may occur irrespective of the myosin type and possibly spontaneously. The above scheme with the deduced kinetic constants predicts the following crossbridge distributions at 5 mM MgATP2- and 8 mM Pi:AM (3%), AM S (15%), AM*S (14%), Det (50%), AM*DP (6%), and AM*D (12%). The actual number of attached crossbridges was measured to be 51 +/- 4% by the stiffness ratio during activation and after rigor induction, and a strong correlation was seen with the prediction. Our results are consistent with the hypothesis that force generation occurs at the Det-->AM*DPi transition, and the same force is maintained after the release of Pi.     

Cholecystokinin antagonistic activities of loxiglumide

Cholecystokinin (CCK) antagonistic activities of loxiglumide ((+/-)-4-(3,4-dichlorobenzamido)-N-(3-methoxypropyl)-N-pentylgl utaramic acid, CR1505, CAS 107097-80-3) were investigated in the gastrointestine and gallbladder in vivo. Intravenous administration of loxiglumide antagonized the CCK-induced reduction of gastric emptying in rats, acceleration of intestinal transport in mice, increase in ileal motility in rabbits, gallbladder contraction in guinea pigs and acceleration of gallbladder emptying in mice. Orally administered loxiglumide also antagonized the CCK-induced gallbladder emptying in mice. Furthermore, egg yolk-stimulated gallbladder emptying in mice was also inhibited by loxiglumide, indicating that this agent antagonizes not only exogenous but also endogenous CCK. These results demonstrate that loxiglumide is an intravenously and orally effective, potent CCK antagonist.     

Antireflection coating with fluoropolymer for a novel organic nonlinear optical crystal: 8-(4'-acetylphenyl)-1,4-dioxa-8-azaspiro[4.5]decane (ADPA)

Prior to the frequency doubling of a laser diode through a ring resonator, reflection loss on the surface of a novel organic second-order nonlinear optical crystal, 8-(4'-acetylphenyl)-1,4-dioxa-8-azaspiro[4.5]decane (APDA), was decreased. An optically flat crystal surface with a flatness of λ/10 (λ = 633 nm) and surface roughness of 1.5 nm rms was obtained when an ultraprecision diamond turning lathe was used to machine the crystal surface. After this surface was coated antireflectively with an amorphous fluorinated polymer, Teflon AF-2400, the transmittance at 810 nm was increased to 98%. A laser-diode-pumped ring resonator was built with this crystal, and a blue second-harmonic emission at 405.5 nm wassuccessfully generated.     

Impaired neutrophil function in chronic renal failure--dysregulation of surface adhesion molecule expression and phagocytosis

To elucidate the impaired neutrophil function in patients with chronic renal failure, we analyzed the expression of the adhesion molecules, LAM-1, LFA-1, Mac-1, gp150/95 and phagocytosis activity of neutrophils in predialysis and hemodialysis patients by flow cytometry. Further, the response to granulocyte colony-stimulating factor (G-CSF), N-formyl-methionyl-leucyl-phenylalanine (fMLP) and tumor necrosis factor alpha (TNF alpha) were investigated. In hemodialysis patients, the expression of LAM-1 was decreased and that of MAC-1 was increased, indicating the activation of neutrophils. Also in predialysis patients, the same condition of "low LAM-1, high MAC-1" was observed, but to a lesser degree. Phagocytosis activity was significantly decreased in hemodialysis patients, whereas the neutrophils of predialysis patients showed almost the same phagocytosis activity compared to the controls. The responses to G-CSF, fMLP, TNF alpha were significantly reduced both in hemodialysis and predialysis patients. The inadequate activation of neutrophils and impaired response to stimulation may play an important role in uremic patients with regard to increased susceptibility to infections.     

Upper and lower critical solution temperatures in polyethylene solutions

Upper and lower critical solution temperatures have been determined for solutions of polyethylene in n-butyl acetate and n-amyl acetate over the molecular weight range of M_η = 1·36 × 10⁴ to 17·5 × 10⁴. Polyethylene solution in n-butyl acetate displays a smaller miscibility region than that of the polyethylene/n-amyl acetate system, as indicated by the relative positions of their upper and lower critical solution temperatures. Contributions of the energy and the equation of state terms to the χ1 parameter have been examined by an application of the Patterson-Delmas corresponding state theory to the experimental results of the polyethylene solutions.     

Correlation of suppressed linoleic acid metabolism with the hypocholesterolemic action of eritadenine in rats

The dose-dependent effects of dietary eritadenine on the metabolism of linoleic acid and on the plasma cholesterol concentration were investigated to clarify the mechanism of the hypocholesterolemic action of eritadenine in rats. Rats were fed control or eritadenine-supplemented (2 to 20 mg/kg) diets for 14 d. Eritadenine supplementation significantly decreased both the plasma cholesterol concentration and the 20∶4n−6/18∶2n−6 ratio of liver microsomal and plasma phosphatidylcholine (PC) in a dose-dependent manner. Eritadenine was also found to decrease the activity of Δ6 desaturase in liver microsomes; these was significant correlation between the Δ6-desaturase activity and the 20∶4n−6/18∶2n−6 ratio in the PC of liver microsomes (r=0.989, P<0.001) or plasma (r=0.986, P<0.001). Certain plasma PC molecular species, as represented by 16:0-18:2, were increased by eritadenine in a dose-dependent manner, and certain plasma PC molecular species, as represented by 18:0-20:4, were conversely decreased by eritadenine. There was a significant correlation between the plasma total cholesterol concentration and the proportion of the sum of plasma PC molecular species which contain 18:1 or 18:2 in the sn-2 position. These results support the idea that the suppression of linoleic acid metabolism by eritadenine might be associated with the hypocholesterolemic action of eritadenine.     

Phase separation temperatures in the polystyrene—poly(α-methyl styrene)—methylcyclohexane system

The phase separation temperatures (PST) in the ternary system polystyrene (PS) (M_w = 1.75 × 10⁴ g mol⁻¹ — poly(α-methyl styrene) (PαMS) (M_w = 6.0 × 10⁴) — methylcyclohexane (MCH) and the binary systems PS-MCH and PαMS-MCH have been determined by using a He---Ne laser light-scattering apparatus over the total polymer weight fraction (W_{PS + PαMS}) range of 0.018 to 0.80 and various polymer blend ratios. The PST determined at a scattering angle of 0° agreed with those at 90° for the binary systems over polymer concentrations of 0.1 to 0.7 and for the ternary over W_{PS + PαMS} of higher than 0.3. Deviations of the PST determined at an angle of 90° from those at 0° were observed in the ternary system when W_{PS + PαMS} was lower than 0.3. Two phase separation temperatures, at which the intensity scattered from zero angle changed discontinuously, are observed at concentrations lower than W_{PS + PαMS} = 0.042 in the ternary system. The PST in the ternary system decreases monotonically with increasing W_{PS + PαMS} over 0.3 to 0.7. The phase diagram for the PS-PαMS-MCH system at W_{PS + PαMS} = 0.8 is characterized by a maximum PST around − 14°C.     

Technical progresses for PVC production

This review covers recent development of PVC production technologies of the suspension polymerization process, the bulk (mass) polymerization process and the emulsion polymerization process with some historical background. The development of process for the vinyl chloride monomer (VCM) production is also explained briefly. Since the suspension process is regarded to be the most important process with its 80% share of the world total production, this review follows mainly the technology development of the suspension polymerization process. Because of the importance of hygienic problems caused by VCM, the technology development in the field of emission control is also covered.     

A model to predict the amount of calcium hydroxide in concrete containing mineral admixtures

This study examines in detail the degree of reactivity of admixtures, such as fly ash and blast furnace slag, and their effect on the levels of calcium hydroxide in cement paste. Experimental results indicate that reactivity between calcium hydroxide and mineral admixture is dependent on the amount of calcium hydroxide and the degree of hydration of mineral admixtures.From these results, a model was formulated to predict the reaction between calcium hydroxide and mineral admixtures, and its validity verified by comparing calculated data with the data from the tests with cement mortar specimens. The calculated values of calcium hydroxide agree well with the test results. The parameters of the prediction model are dependent on the physical and chemical characteristics of mineral admixtures.