Effects of neuromedin B and GRP-10 on gastrin and insulin release from cultured tumor cells of a malignant gastrinoma

A study relating to gastrin release from gastrinoma cells by neuromedin B and C-terminal decapeptide of gastrin releasing peptide (GRP-10) has not yet been reported. Therefore, we studied the effects of neuromedin B and GRP-10 on gastrin release from cultured dispersed cells prepared from both the primary tumor in the pancreas and the metastatic tumor in the liver from a case of malignant Zollinger-Ellison syndrome. Both the primary and metastatic tumors obtained by a curative operation contained similar concentrations of gastrin and glucagon, whereas the primary tumor contained 10 times more insulin than the metastatic tumor. Gastrin release from cultured cells of both tumors was suppressed by 0.1 and 10 nM neuromedin B and tended to be suppressed by 0.1-10 nM GRP-10. However, insulin release from cultured cells of the pancreatic tumor was stimulated by GRP-10, but not by neuromedin B. These results might suggest that receptor function for the bombesin family peptides is abnormal in gastrinoma cells in both primary and metastatic tumors, and that a major source of insulin secretary cells is the contaminated normal islet cells in the primary tumor.     

Formation of amino acids from reactor-irradiated ammonium acetate

Ammonium acetate in various conditions was irradiated in a reactor to examine the contributions of both the reactor radiations and recoiled¹⁴C nucleis to form the biologically interesting molecules. Present investigations demonstrated that several amino acids, glycine, alanine, -alanine and GABA, and may-be aspartic acid, serine and valine by prolonged irradiation, were formed in the aqueous solutions of ammonium acetate.¹⁴C-radioactivities were also found distributed in these amino acids. However, no special relationship between¹⁴C-radioactivity and these amino acids formed was observed.     

Preparation of Uridine Diphosphate-N-Acetylgalactosamine from Uridine Diphosphate-N-Acetylglucosamine by Using Microbial Enzymes

A method was developed for the large scale preparation of uridine diphosphate-N-acetylgalactosamine (UDP-GalNAc) from uridine diphosphate-N-acetylglucosamine (UDP-GlcNAc) by means of microbial enzymes. With Bacillus subtilis cell-free extract as a source of UDP-GlcNAc 4-epimerase, about 35% of the UDP-GlcNAc added was converted to UDP-GalNAc. After the residual UDP-GlcNAc was degraded to uridine triphosphate and N-acetylglucosamine-1-phosphate with a protamine-treated extract of bakers' yeast as a source of UDP-GlcNAc pyrophosphorylase, UDP-GalNAc was separated by anion-exchange column chromatography. The nucleotide was recovered by adsorption on charcoal and elution with ammoniacal ethanol. The final yield was about 100 μmol.     

Effect of Cibacron Blue F3GA on phosphoglycerate kinase of Lactobacillus plantarum and phosphoglycerate mutase of Leuconostoc dextranicum

Blue dextran or Cibacron Blue F3GA has been shown to inhibit yeast phosphoglycerate kinase [EC 2.7.2.3] competitively with respect to ATP (Thompson et al. (1975) Proc. Natl. Acad. Sci. U.S. 72, 663--667; Beissner and Rudolph (1979) J. Biol. Chem. 254, 6273--6277). However, we have found that phosphoglycerate kinase of Lactobacillus plantarum was inhibited by Cibacron Blue F3GA, the blue chromophore of blue dextran, noncompetitively with respect to ATP, but competitively with respect to 3-phosphoglycerate. Further inhibition studies with Cibacron Blue F3GA suggest that one molecule of the dye was bound per molecule of phosphoglycerate kinase at a saturated level of either substrate, but two molecules of the dye were bound per molecule of the kinase with an unsaturated level of either substrate used as a fixed substrate. Furthermore, phosphoglycerate mutase [EC 2.7.5.3] of Leuconostoc dextranicum was also inhibited by Cibacron Blue F3GA competitively with respect to 3-phosphoglycerate and noncompetitively with respect to 2,3-bisphosphoglycerate. These results suggest that the 3-phosphoglycerate-binding site on both phosphoglycerate kinase and phosphoglycerate mutase can interact with Cibacron Blue F3GA.     

Thermal analysis of bacteriophage T4.

The process of bacteriophage T4 morphogenesis was studied using a heat leakage scanning calorimeter. Thermograms of defective mutant 49 (am NG727) in permissive and non-permissive cells of $\text{Escherichia coli}$ showed a difference in thermal properties between packaged and non-packaged DNA molecules. $\text{In vivo}$, non-packaged DNA carried out their thermal transition at 85°C, the same temperature as that of T4 DNA melting measured in the standard saline citrate buffer, while the packaged DNA gave a sharper peak at 87°C due to some interaction with the head shell structure. Empty head shells showed a sharp heat absorption peak at 89°C both $\text{in vivo}$ and $\text{in vitro}$, indicating the high degree of cooperativity in their conformational changes.     

Asymmetrical radical formation in D- and L-alanines irradiated with yttrium-90β-rays

Radical formation in^{9 0}Y--irradiated D- and L-alanines was studied using ESR. It was observed that the relative radical concentration by -irradiation was distinguishably (13.9–21.5%) more in D-alanine than in L-alanine. Discussion was made on the possible mechanisms for the observed results.     

Bacterial oxidation of polyethylene glycol.

The metabolism of polyethylene glycol (PEG) was investigated with a synergistic, mixed culture of Flavobacterium and Pseudomonas species, which are individually unable to utilize PEGs. The PEG dehydrogenase linked with 2,6-dichlorophenolindophenol was found in the particulate fraction of sonic extracts and catalyzed the formation of a 2,4-dinitrophenylhydrazine-positive compound, possibly an an aldehyde. The enzyme has a wide substrate specificity towards PEGs: from diethylene glycol to PEG 20,000 Km values for tetraethylene glycol (TEG), PEG 400, and PEG 6,000 were 11, 1.7, and 15 mM, respectively. The metabolic products formed from TEG by intact cells were isolated and identified by combined gas chromatography-mass spectrometry as triethylene glycol and TEG-monocarboxylic acid plus small amounts of TEG-dicarboxylic acid, diethylene glycol, and ethylene glycol. From these enzymatic and analytical data, the following metabolic pathway was proposed for PEG: HO(CH2CH2O)nCH2CH2OH leads to HO(CH2CH2O)nCH2CHO leads to HO(CH2CH2O)nCH2COOH leads to HO(CH2CH2O)n-1CH2CH2OH.     

A change in membrane microviscosity of mouse neuroblastoma cells in association with morphological differentiation

Changes in membrane microviscosity as well as in membrane constituents of mouse neuroblastoma clone N-18 were studied in association with neurite formation. The membrane microviscosity studied by fluorescence technique increased with the formation of neurites. The concomitant increase increase in the ratio of cholesterol to phospholipids was also observed.     

Head Rotation or Dissociation?: A Study of Exponential Rate Processes in Chemically Skinned Rabbit Muscle Fibers When MgATP Concentration Is Changed

The mechanical response of fully activated muscle bundles (one to five fibers) to sinusoidal length perturbation (~0.4% L₀) was studied as a function of MgATP concentration. The frequency response (0.25-167 Hz; corresponding to 1 ms time resolution) of chemically skinned rabbit muscle fibers was resolved into three exponential rate processes, (A), (B), and (C). At 20°C, the apparent rate constants associated with the fast exponential lead (2πc = 388-588 s^-1) and the oscillatory work (2πb = 59-116 s^-1) both increase with increment of the MgATP concentration from 1 to 5 mM, and they both saturate for further increase. Over the whole range of MgATP concentrations the slow exponential lead (2πa = 9-7 s^-1) remains constant. The effect of MgATP on processes (B) and (C) can be interpreted in the context of the biochemical evidence, in which MgATP enters the cross-bridge cycle after the desorption of the product, and the binding of MgATP to rigorlike cross-bridges promotes a rapid dissociation of actomyosin (Lymn and Taylor, 1971. Biochemistry. 10:4617-4624.). The effect is not predicted by a model for force generation in which head rotation dominates the fast component (“stage 2” of Huxley and Simmons, 1971. Nature (Lond.). 233:533-538. and 1973. Cold Spring Harbor Symp. Quant. Biol. 37:669-680.), and head dissociation dominates the slow component (“phase 4” of Huxley, 1974. J. Physiol. (Lond.). 243:1-43; Julian et al., 1974. Biophys. J. 14: 546-562.).     

Synthesis of 2-acetamido-2-deoxy-5-thio-d-glucopyranose

2-Acetamido-2-deoxy-5-thio-d-glucopyranose (12) has been synthesized from methyl 2-acetamido-2-deoxy-5,6-O-isopropylidene-β-d-glucofuranoside (1). Benzoylation of 1, followed by O-deisopropylidenation, gave methyl 2-acetamido-3-O-benzoyl-2-deoxy-β-d-glucofuranoside, which was converted, via selective benzoylation and mesylation, into methyl 2-acetamido-3,6-di-O-benzoyl-2-deoxy-5-O-mesyl-β-d-glucofuranoside (5). Treatment of 6, formed by the action of sodium methoxide in chloroform on 5, with thiourea gave methyl 2-acetamido-2,5,6-trideoxy-5,6-epithio-β-d-glucofuranoside (7), which was converted into the 5-thio compound 9 by cleavage of the epithio ring in 7 with potassium acetate. Alkaline treatment of 10, derived from 9 by hydrolysis, afforded the title compound. Evidence in support of the structures assigned to the new derivatives is presented.