High affinity binding of 5-hydroxytryptamine to some membrane preparations from cattle brain. Relationship to lysergic acid diethylamide (LSD)]

5 hydroxytryptamine binds to crude brain membrane preparations with two different affinities (KD = 1 to 2 X 10(-9) M for the highest, 1 to 2 X 10(-8) M for the lowest). LSD also binds with two affinities (KD = 3 to 4 X 10(-9) M and KD = 2 to 3 X 10(-8) M). Subcellular distribution of these sites shows that binding involves the two binding affinities in microsomal membranes but solely the high affinity binding sites are present in purified synaptosomal membranes. High affinity sites for 5 HT and for LSD are different as no direct competitive inhibition is observed in that case. On microsomal membranes, direct relationship occurs between low affinity binding for 5 HT and high affinity binding for LSD.     

A histochemical demonstration of the Na+ + K+-ATPase activity in the thyroid and the effect of cyclic adenosine monophosphate (c-AMP).

With a suitable modification of the Farquhar and Palade technique the Na+ + K+-ATPase activity in guinea-pig thyroid is demonstrated. The addition of c-AMP (5 X 10(-6) M or 1.5 X 10(-5) M) to the incubation media produced an apparent intensification of the Na+ + K+ -ATPase activity in the thyroid.     

Mechanical and biochemical characterization of the contraction elicited by a calcium-independent myosin light chain kinase in chemically skinned smooth muscle

The contraction induced by a Ca2+-independent myosin light chain kinase (MLCK-) was characterized in terms of isometric force (Fo), immediate elastic recoil (SE), unloaded shortening velocity (Vus), shortening under a constant load and ATPase activity of chemically skinned smooth muscle preparations. These parameters were compared to those measured in a Ca2+ -induced contraction to assess the nature of cross bridge interaction in the MLCK-induced contraction. Fo developed in chicken gizzard fibers as well as SE were similar in contractions elicited by either agent. Vus in the contraction induced by MLCK-(0.36 mg/ml) was similar though averaged 39.3 +/- 8.9% less than Vus induced by Ca2+ (1.6 X 10(-6) M) in the control fibers. Addition of Ca2+ (1.6 X 10(-6) M) to a contraction induced by MLCK-resulted in small increases in both Fo and Vus. Shortening under a constant load was similar for both types of contractions. The contraction induced by MLCK-was accompanied by an increased rate of ATP hydrolysis. The MLCK-induced contraction is thus kinetically similar though not identical to a contraction induced by Ca2+. We conclude that with respect to actin-myosin interaction, MLCK-and Ca2+ -induced contractions are similar.     

Somatostatin and 3-oxy-methyl-D-glucose (3-OMG) uptake in isolated chicken intestinal epithelial cells

The direct effect of somatostatin on the absorption of 3-oxymethylglucose in epithelial cells isolated from the small intestine of chicken was studied. The presence of somatostatin in the incubation medium at concentrations of 3.5 X 10(-8) M and 7 X 10(-8) M produced significant dose-dependent increases in the accumulation of sugar in the enterocytes. This effect might be due to an increase in the cell membrane permeability caused by hormone action.     

VIP and histamine H2 receptor activity in human fetal gastric glands

Vasoactive intestinal peptide (VIP, EC50 = 6.4 X 10(-10)M) and histamine (EC50 = 3 X 10(-6)M) activated the cyclic AMP generating system in gastric glands isolated from two human fetuses at 23 weeks gestation. Histamine antagonism by the H2 receptor blockers cimetidine (Ki = 0.35 X 10(-6)M) and ranitidine (ki = 0.51 X 10(-7)M) clearly characterized the histaminic activation as being of the H2 type. It is suggested that these two vasoactive hormones may operate as neurocrine/paracrine regulators of the differentiation and/or function of the human gastric mucosa in utero.     

Periodate oxidation of lymphocyte membrane glycoconjugates]

Mouse spleen cells free of erythrocytes were suspended in PBS at a concentration of 2 X 10(7) cells/ml and mixed with an equal volume of sodium periodate in PBS for 10 min. at 4 degrees C to give a final concentration of periodate ranging from 10(-4) M to 5 X 10(-3) M. The cells were then washed and suspended (60 X 10(6) ml) in PBS containing 3H-labelled sodium borohydrate and incubated for 30 min, at 23 degrees C. Following this, the cells were washed and the pellets treated with H2SO4 0.1 N for 60 min. at 80 degrees C. Compounds liberated by such treatment, were identified by chromatography as derivates of sialic acid. The data provide direct evidence that the mitogenic effect of sodium periodate is associated to the oxidation of the sialic acid residues on the lymphocyte membrane.     

基于MATLAB的AA—HPA—AMPS—AM聚合物阻垢剂合成及其性能研究

通过溶液聚合方法,以过硫酸铵为引发剂,丙烯酸、丙烯酸羟丙酯、2-丙烯酰胺-2-甲基丙磺酸、丙烯酰胺为单体,合成AA-HPA-AMPS-AM聚合物.固定聚合物浓度为4 mg/L,分别考查反应时间、反应温度（X1）、引发剂用量（X2）、单体配比（AA：HPA以X3计、AMPS：AM以X4计）对聚合物阻CaCO3垢性能的影响,并设计了正交实验,得出当聚合物在80℃、引发剂用量为10%、M（AA）：M（HPA）为0.25、M（AMPS）：M（AM）为0.4时,阻CaCO3垢率最高为52.9%.为探究此聚合物是否有更高的阻垢性能,应用MATLAB对正交实验结果进行分析及验证,得知：聚合物阻CaCO3垢效率y与各影响因素X之间基本满足y=146.349 7-0.926 7x1-49.765 8x3-28.220 9x4.最佳聚合条件为x1=75、x3=0.15、X4=0.15,y为68.35%.     

Effect of pulsing electromagnetic fields on DNA synthesis in mammalian cells in culture

DNA synthesis in Chinese hamster V79 cells was significantly enhanced when they were exposed to weak, pulsing electromagnetic fields generated by specific combinations of the pulse width (25 microseconds), frequency (10, 100 Hz) and magnetic intensity (2 X 10(-5), 8 X 10(-5) T). Conversely the DNA synthesis of cells in the fields at 4 X 10(-4) T was repressed to 80% of that in controls not exposed to the fields.     

Role of calcium in the histamine release induced by D-galactosamine from rat mast cells

Rat peritoneal mast cells were isolated and purified by differential centrifugation in Ficoll. Cells pooled from three to four rats were suspended at approximately 10(6) cells/ml in a buffered salt solution and incubated for 1 h at 37 degrees C in 300 microliter volumes in the absence or presence (9 X 10(-4) M) of calcium chloride. Addition of D-galactosamine hydrochloride (DGM; 2.8 X 10(-4)M) caused (in addition to basal release) a mean +/- SEM percent histamine release of 15.7 +/- 5.2 in the presence of Ca++ and 19 +/- 4.9 in the absence of Ca++ (p greater than 0.05). It is suggested that D-galactosamine does not require extracellular Ca++ for the release of histamine from the rat mast cell.     

Monoclonal antibodies to L-asparaginase

Five hybridomas secreting monoclonal antibody to E. coli L-asparaginase were isolated. These monoclonal antibodies were classified into 3 different subclasses; Ig G1 (1 clone), Ig G2 (2 clones) and Ig G3 (2 clones). One of them possessed anti-L-asparaginase neutralizing activity. Four antibodies examined demonstrated a linear Langmuir binding plot and binding affinities, with equilibrium dissociation constant (Kd) ranging between 2.5 X 10(-9) M and 6.3 X 10(-10) M. The monoclonal antibodies should be useful probes for investigation of the enzyme activity.     

Effect of sodium octanoate on leucine incorporation into protein of rat liver slices and of Yoshida ascites hepatoma cells.

7.38 X 10(-4) M octanoate does not significantly modify leucine incorporation into protein of rat liver slices, while in hepatoma cells a 19% inhibition has been noted. 3.69 x 10(-3) M octanoate reduces leucine incorporation to about the same extent (71-76%) in both liver slices and hepatoma cells.     

Effects of bunaphtine on 45Ca movements in rat aortic smooth muscle

The effect of bunaphtine (BNA, 5 X 10(-5)M) on La3+ -resistant 45Ca content and 45Ca efflux was studied on rat aortic smooth muscle. BNA decreased both control and norepinephrine-stimulated La3+-resistant 45Ca content and increased the 45Ca efflux. These effects could explain the inhibition of the contractile responses induced by BNA.     

Phosphoramidon enhances allatostatin-mediated inhibition of juvenile hormone biosynthesis in the corpora allata of the cockroach, Diploptera punctata.

Use of enkephalinase inhibitor phosphoramidon in the in vitro radiochemical assay for juvenile hormone biosynthesis enhanced allatostatin-mediated inhibition of hormone production by corpora allata of the cockroach, Diploptera punctata. Significant increases in inhibition in day 2 virgin female CA by AST 1 (at 10(-7) M) and AST 4 (10(-8)-10(-7) M) were observed in the presence of phosphoramidon (10(-5) M or greater). No significant increase in inhibition were seen in CA from day 6 mated females with AST 4 (10(-9)-10(-7) M) and phosphoramidon combined. Phosphoramidon alone had no effect on JH biosynthesis. Analysis of allatostatin content of the CA, as determined by ELISA, revealed that addition of phosphoramidon to the medium increased the endogenous allatostatin content in CA of virgin and mated females. The similarity in primary structure between allatostatins and enkephalin-like peptides and their similar distribution makes it probable that phosphoramidon acts by preventing breakdown of allatostatins within the CA.     

Inhibitors of the acrosomal proteinase acrosin: Human urinary trypsin inhibitor (UTI) and 4-(2-carboxyethyl) phenyl trans 4-aminomethylcyclohexanecarboxylate hydrochloride (DV-1006)

Summary Human urinary trypsin inhibitor (UTI) and (4-(2-carboxyethyl) phenyl trans 4-aminoethylcyclohexanecarboxylate hydrochloride (DV-1006) competitively inhibited the human acrosomal proteinase acrosin; Ki values were 1.2×10^–8M and 9.4×10^–7 M, respectively.     

Effects of cycloheximide on protein synthesis in human lung tumors, regenerating rat liver and hepatomas

10(-4) M cycloheximide (CHM) inhibits leucine incorporation to about the same degree in slices of human lung tumors, rat hepatomas, regenerating livers and normal tissues. At 10(-6) M, CHM has a more pronounced effect on tumor tissue and regenerating liver than on normal tissues. 10(-8) M CHM stimulates protein synthesis in normal rat liver slices.     

Demonstration of a receptor for 5 alpha-androstane-3 beta, 17 beta-diol in the cytosol of the anterior pituitary of prepubertal male rats]

The presence of a specific receptor for 5alpha-androstan-3beta, 17beta-diol (3beta-diol) in the pituitary cytosol from prepubertal male rats was demonstrated. Its characteristics were: Ka = 5.2.10(7) M-1 KD = 1.9 X 10(-8) M, number of specific binding = 8.7 10(-14) moles per mg of proteins. Its sedimentation constant was 3 S. Competition assays showed that only 3beta-diol itself and estrogens were able to compete for the binding sites for 3beta-diol. Androgens, including 3alpha-diol, were inefficient. This receptor was found only in pituitary cytosol, it was missing from hypothalamic or cortical cytosols. This special localization seemed to foreshadow a specific role for 3beta-diol in the anterior hypophysis.     

Inhibition of prostaglandin-induced cyclic AMP accumulation in the rat anterior pituitary by alrestatin.

Alrestatin at 25-1 X 10(-4) M inhibited the accumulation of cyclic AMP induced by prostaglandin E2, but not theophylline, in the rat anterior pituitary in vitro. Somatostatin, at lower concentrations, inhibited both; maximal inhibition of the prostaglandin effect was greater with alrestatin. As cyclic AMP is considered to be a mediator in induced-hormonal release, it appears from the present findings that alrestatin may be of potential use in altering hormonal release.     

Inhibition of lymphocyte blastogenesis by diazepam, meprobamate, and other psychotropic drugs]

Imipramine, diazepam, chlordiazepoxide, and meprobamate inhibit incorporation of 3H-thymidine in human lymphocytes in culture. For the first three drugs, 50% inhibition occurs at a concentration of 5 X 10(-5) M, and for meprobamate at a concentration of 10(-3 M. Ethanol has no action up to 10(-1) M.     

The polyphosphate synthetase of Saccharomyces cerevisiae]

The polyphosphate-synthetase, isolated from a homogenate of phosphate starved cells, catalyses the synthesis of linear polyphosphates from orthophosphate. It is localized in the membrane fraction which deposits between 400 and 1000 X g; its optimal pH is 7.1; its KM toward orthophosphate is 4.0 X 10(-4) M; ATP stimulates the reaction. The enzyme synthezises especially polyphosphates with short chain length.     

Evidence of a direct action of triiodothyronine (T3) on the cell membrane of GH3 cells: an electrophysiological approach

Electrophysiological experiments demonstrate that triiodothyronine (T3) exerts a direct effect on the membrane of a strain of cultured rat pituitary tumor cells, GH3/B6. These cells respond to pressure application of T3 (2-5 nl, concentration 1 X 10(-10) M) with an increase in the membrane resistance (Rm) and a hyperpolarization. Spontaneously firing cells become silent.