Clithioneine,an amino acid betaine from clitocybe acromelalga

A new amino acid betaine, clithioneine, was isolated from a poisonous mushroom Clitocybe acromelalga, and its structure was established on the basis of spectral analyses and chemical degradation studies.     

Control of heart rate variability by cardiac parasympathetic nerve activity during voluntary static exercise in humans with tetraplegia.

Heart rate (HR) is controlled solely by via cardiac parasympathetic outflow in tetraplegic individuals, who lack supraspinal control of sympathetic outflows and circulating catecholamines but have intact vagal pathways. A high-frequency component (HF; at 0.15-0.40 Hz) of the power spectrum of HR variability and its relative value against total power (HF/Total) were assessed using a wavelet transform to identify cardiac parasympathetic outflow. The relative contribution of cardiac parasympathetic and sympathetic outflows to controlling HR was estimated by comparing the HF/Total-HR relationship between age-matched tetraplegic and normal men. Six tetraplegic men with complete cervical spinal cord injury performed static arm exercise at 35% of the maximal voluntary contraction until exhaustion. Although resting cardiac output and arterial blood pressure were lower in tetraplegic than normal subjects, HR, HF, and HF/Total were not statistically different between the two groups. When tetraplegic subjects developed the same force during exercise as normal subjects, HF and HF/Total decreased to 67-90% of the preexercise control and gradually recovered 1.5 min after exercise. The amount and time course of the changes in HF/Total during and after exercise coincided well between both groups. In contrast, the increase in HR at the start of exercise was blunted in tetraplegic compared with normal subjects, and the HR recovery following exercise was also delayed. It is likely that, although the withdrawal response of cardiac parasympathetic outflow is preserved in tetraplegic subjects, sympathetic decentralization impairs the rapid acceleration of HR at the onset of exercise and the rapid deceleration following exercise.     

Effect of 5-Campestenone (24-methylcholest-5-en-3-one) on Zucker diabetic fatty rats as a type 2 diabetes mellitus model.

We examined the therapeutic effects of dietary exposure to 5-campestenone (24-methylcholest-5-en-3-one), an enone derivative of campesterol, in Zucker diabetic fatty (ZDF) rats, an animal model of type 2 diabetes mellitus. Dietary 0.6 % exposure to 5-campestenone caused marked reduction in hemoglobin A1c (HbA1c), plasma total cholesterol, triglycerides and non esterified fatty acid (NEFA). In particular, plasma triglyceride levels were reduced in the 0.6 % 5-campestenone-fed group to about 25 % of that in the control group. In the oral glucose tolerance test (OGTT) at three and seven weeks after the beginning of treatment, 5-campestenone limited the rise of blood glucose levels by oral administration of glucose dose-dependently. Amounts of adipose tissue in the retroperitoneum and periepididymal area as well as abdominal subcutaneous fat were significantly decreased in animals fed 0.6 % 5-campestenone. The blood leptin concentration on the final day of feeding was significantly in animals administered 5-campestenone. No obvious anomaly due to consumption of 5-campestenone was detected in necropsy or clinical observations.     

Gastrin/cholecystokinin-like immunoreactivity in human blood cells

In the gastrin and/or cholecystokinin-like immunoreactivity (G/CCK-LI) elution patterns of blood cells in human adults, erythrocyte (RBC) elution pattern has three peaks which are coeluted with gastrin-34 (G34), gastrin-17 (G17) and V_t, and polymorphonuclear leukocyte (PMN) and mononuclear cell (MNC) elution patterns have four peaks which are coeluted with V_o, G34, G17 and V_t. The content of G/CCK-LI in RBC is 1.20±0.54 fmole/10⁸ cells (means±SD). Than in PMN and MNC is 1.44±0.67 p mole/10⁸ cells and 1.67±0.76 p mole/10⁸ cells, respectively.     

Increase of transferrin receptors in regenerating rat liver cells after partial hepatectomy

The change of transferrin receptors in regenerating rat liver cells after partial hepatectomy was demonstrated. The binding of 125I-labeled transferrin to the cells began to increase after 24 h of partial hepatectomy and reached about double that of the non-operated normal rat liver cells. A Scatchard analysis of binding parameters showed 1.62 X 10(5) (Ka: 1.04 X 10(7) M-1) in normal cells and 3.36 X 10(5) (Ka: 1.23 X 10(7) M-1) in regenerating cells. This reflected on increase of transferrin receptor number and little change occurred in the binding affinity between transferrin and its surface receptor.     

The structure of rabbit muscle phosphoglucomutase at intermediate resolution

The three-dimensional structure of rabbit phosphoglucomutase has been determined to 2.7 A resolution by a combination of isomorphous and molecular replacement techniques. Heavy atom positions were found by using vector search and difference Fourier methods. The two molecules in the asymmetric unit form a dimer with its 2-fold axis perpendicular to and intersecting with a crystallographic 4(1) axis. Thus, the dimers are arranged so that they form fibers that are coincident with the 4(1) axes. A polypeptide model, corresponding with the known residue sequence, has been fitted to the electron density map to produce a structure that consists of four domains. All four have an alpha/beta structure; the first three have a somewhat similar topology that is based on a mixed parallel/antiparallel beta sheet, whereas the fourth is based on an antiparallel sheet. The active site lies between the four domains, with the phosphoserine residue in the first domain and some of the probable substrate-binding residues in the fourth and final domain. The carboxyl edges of all four sheets are directed towards the active site region, which lies in a deep crevice.     

Partial purification and characterization of phorbol ester-regulated translational inhibitor(s) in human HL-60 leukemic cells

Addition of nanomolar concentration of the phorbol ester 12-O-tetradecanoyl phorbol 13-acetate (TPA) to the human promyelocytic HL-60 leukemia cells is associated with a cessation of cellular proliferation and a subsequent differentiation into macrophage-like cells. Because the growth rate of mammalian cells is tightly coupled to the functions of the protein synthetic machinery, we have examined whether TPA induces a change in HL-60 translational functions. Addition of control HL-60 cell extracts to rabbit reticulocyte lysates results in a pronounced inhibition of protein synthesis, while TPA-treated HL-60 cell extracts are significantly less inhibitory. The reduction in TPA-induced translational inhibitory activity can be observed after a 3-6-h treatment and reaches a maximum after 24 h. Fractionation of control cell extracts on DEAE-cellulose columns reveals two inhibitory activities, eluting at 100 and 350 mM KCl, respectively. The DEAE-100 inhibitor(s) is further resolved into two activities by heparin-agarose column chromatography (HEP-100 and HEP-250). TPA treatment of HL-60 cells for 48 h completely eliminates the HEP-250 inhibitory activity and reduces the HEP-100 and the DEAE-350 inhibitory activities by 50 and 25%. Inhibition of protein synthesis in rabbit reticulocyte lysates by DEAE-100 inhibitory activities can be partially reversed by the addition of globin mRNA while translational inhibition by DEAE-350 inhibitor(s) can be reversed by addition of eukaryotic initiation factor (eIF) 2 or fructose 6-phosphate. The DEAE-100 inhibitor(s) causes extensive degradation of radioactive polynucleotides while the DEAE-350 inhibitor(s) is capable of phosphorylating both the alpha- and the beta-subunits of the highly purified rabbit reticulocyte initiation factor eIF-2. These data show that the DEAE-100 inhibitor(s) contains a nuclease while the DEAE-350 inhibitor(s) is associated with eIF-2 alpha and eIF-2 beta protein kinases.     

Induction of human HL-60 leukemic cell differentiation by immune interferon is accompanied by an increase in NADase activity and by a decrease in DNA-binding proteins

The effects of highly purified human immune interferon (IFN-gamma) on the differentiation of human promyelocytic HL-60 leukemic cells have been studied. The addition of 100 units/ml interferon to HL-60 cells for 5 days results in morphological changes characteristic of macrophages. At the biochemical level, there is a 3-fold increase in the specific activity of the enzyme NADase. Kinetic analysis shows that IFN-gamma causes an increase in the Vmax of NADase without affecting the apparent Km. Pulse labeling experiments with [35S] methionine show a marked change in the de novo synthesis of several proteins in the course of interferon treatment. Chromatography on DNA-agarose show that after treatment with interferon for 24 or 48 h, there is a 60-70% decrease in newly synthesized proteins which bind DNA-agarose and can be subsequently displaced from the column with 2% SDS containing buffer (from 7.7-8.7% bound in control cell extracts to 2.6-3.1% bound in interferon treated cell extract).     

Effects of External Ca2+ on K+ Permeability of the Elongating Region of Mung Bean Roots under High KCl Stress

Simultaneous measurements of the extracellular potential andthe K⁺(⁸⁶Rb) efflux, and of the intracellular and extracellularpotentials of the cortical cells were used to study the effectsof external Ca²⁺ on the plasma membrane K⁺(⁸⁶Rb) permeabilityin two-day-old mung bean (Vigna mungo L. Hepper, ‘Blackmatpe’) roots under high KCl stress. The K⁺ efflux wasenhanced by a high KCl solution (>7.5 mM), and addition of0.5 mM Ca²⁺ could suppress this efflux. The removal of membrane-associatedCa⁺ from the root surface with EDTA led to a recovery of theK⁺ efflux along with a marked decrease in the extracellularpotential. (Received November 19, 1986; Accepted March 6, 1987)     

An adenosine uptake blocker,propentofylline, reduces glutamate release in gerbil hippocampus following transient forebrain ischemia

In the present study, the effect of the adenosine uptake blocker, propentofylline (HWA 285) on the extracellular concentration of several amino acids including glutamate, glycine and taurine following 10 min of forebrain ischemia in gerbil hippocampus was investigated using in vivo microdialysis. Pretreatment with HWA 285 (20 mg/kg i.p.) significantly reduced the extracellular concentration of glutamate following ischemia but did not significantly alter levels of other amino acids such as glycine and taurine. These findings suggest that the neuroprotective effect of HWA 285 may be associated with inhibition of glutamate release in the gerbil hippocampus.