Effect of neurotensin on pancreatic function in man

The effect of neurotensin on submaximally-stimulated hepatobiliary and pancreatic secretion was studied in 6 healthy subjects. An intravenous infusion of neurotensin 1.4 ± 0.3 pmol/kg/min, designed to reproduce plasma neurotensin immunoreactivity levels within the physiological range, produced a significant increase in pancreatic bicarbonate output. Plasma concentrations of pancreatic polypeptide rose by 83 ± 16 pmol/l and were associated with a small reduction in trypsin, but no significant change in bilirubin outputs.     

Fatty acid composition of oil synthesized byaspergillus nidulans

The filamentous fungusAspergillus nidulans Eidam strain 300 was found to be capable of synthesizing 24.9 % oil of remarkably low free fatty acidity, in a chemically defined medium with 34 % glucose as sole carbon source. Although the total content of oil synthesized was less, utilization of the carbon source is better as shown by the high (8.4) fat coefficient. The major component fatty acids of the oil were palmitic, stearic, oleic and linoleic and are influenced by the source of carbon. Palmitoleic acid is present in traces, confirming thereby the general observation that high oil formers produce oil of low hexadecenoic acid content. The relatively high stearic acid content of the oil distinguishes it from those of other microorganisms and resembles the oil produced by certain tropical plants, such asMadhuca latifolia.     

Purification and properties of milk-clotting enzyme from Bacillus subtilis K-26

A milk-clotting enzyme from Bacillus subtilis K-26 was purified by gel filtration and ion-exchange chromatography resulting in a 24-fold increase in specific activity with an 80% yield. Polyacrylamide gel electrophoresis and ultracentrifugel analysis revealed that the purified enzyme was homogeneous and had a molecular weight of 27,000 and a K_m of 2.77mg/ml for κ-casein. The enzyme was most stable at pH 7.5 and showed increasing clotting activity with decrease in milk pH up to 5.0. The maximum milk-clotting activity was obtained at 60°C, but the enzyme was inactivated by heating for 30 min at 60°C. The enzyme was irreversibly inhibited by EDTA and unaffected by DFP. Heavy-metal ions (Hg²⁺, Pb²⁺) inactivated the enzyme.     

Characterization of the Ehrlich ascites tumor plasma lipoproteins.

1. The lipoproteins of the Ehrlich ascites tumor plasma were separated into 3 distinct fractions, very low density, low density and high density lipoproteins by preparative ultracentrifugation combined with agarose column chromatography. 2. High density lipoproteins contained 74% of the total protein in the lipoproteins. By contrast, most of the lipids were present in the very low density lipoprotein fraction. 3. The fatty acid compositions of the cholesteryl esters were appreciably different in the very low, low and high density lipoproteins, whereas phospholipid and triacylglycerol fatty acid compositions were quite similar in the 3 lipoprotein fractions. 4. Very low and high density apoprotein electrophoretic patterns on sodium dodecyl sulfate-acrylamide gels were similar to those observed in the corresponding lipoprotein fractions obtained from other mammalian species. The low density fraction, however, contained 7 apoprotein bands, and 32% of the low density apoprotein was soluble in tetramethyl urea. 5. The average molecular weights as determined by analytical ultracentrifugation were 2-10(7) (very low density), 6-10(6) (low density) and 4.4-10(5) (high density).     

Studies on the production of bacterial rennet in a pilot plant fermentor

An attempt was made to find out the optimum aeration and agitation rates on the production of bacterial rennet from Bacillus sublilis K-26 using 5% wheat bran medium in a 13 liter fermentor. The enzyme activity and the growth rate were shown to increase with an increase in the rate of agitation. The fermentation experiments carried out at an agitation rate of 400 rpm showed an approximate threefold increase in enzyme activity with a considerable decrease in the fermentation time over those agitated at 200 and 300 rpm. The beneficial effect of a higher oxygen rate was observed for enzyme production occurring at a lower agitation rate. The inoculum activity and the varying amounts of antifoam agent which were added showed no apparent effect either on the total incubation time or on the final enzyme activity. It has been suggested that an agitation rate of 400 rpm with an aeration level of 3000 cc/min are the optimum values for the efficient production of bacterial rennet from B. subtilis K-26 using 5% wheat bran medium in a 13 liter fermentor.     

Vasoactive intestinal polypeptide stimulates nonovarian progesterone secretion in rabbits

Recent experiments conducted in this laboratory have shown that intravenous infusions of vasoactive intestinal polypeptide (VIP) induced significant increases in plasma progesterone (P) in female rabbits. The purpose of this study was to determine the organ source of this P and to clarify the mechanisms by which it is induced. Intravenous infusions of VIP (37.5, 75, and 150 pmol/kg per min for 60 min) produced acute dose-dependent increases in plasma P in intact estrous rabbits. In ovariectomized (OVX) animals, VIP infusion (75 pmol/kg per min) produced a P increase of the same magnitude. In animals both OVX and adrenalectomized (ADX), this VIP effect was eliminated. The only significant change noted in luteotropic hormone (LH) or follicle stimulating hormone (FSH) was a decrease in FSH immediately following VIP infusion (150 pmol/kg). VIP infusion significantly increased plasma cortisol in intact and OVX animals, but not in OVX/ADX animals. It is concluded that VIP primarily stimulates the adrenal component of P secretion in the rabbit, via mechanisms independent of LH or FSH.     

Tritium labeling of thermolysin, elastase, and ribonuclease by exposure to tritium gas at low pressure

The bacterial metalloendoprotease thermolysin, bovine pancreatic ribonuclease, and porcine pancreatic elastase have been tritiated by exposure to subcurie amounts of tritium gas at pressures below 50 mTorr for periods of 1 to 6 h. Thermolysin, ribonuclease, and elastase have been purified to specific radioactivities of 15, 5, and 1 Ci/mol, respectively. Amino acid analyses of the tritiated enzymes revealed higher relative specific radioactivities for His, Pro, and Phe in all three proteins while Val and Ile were among the residues with the lowest relative specific radioactivities. The recovery of enzyme activity was always greater than 95% and the formation of tritiated decomposition products was not observed. This lowpressure gas exposure process requires less tritium gas and less time than the original method of Wilzbach to achieve equal or higher levels of tritium incorporation. In addition, the enzymes were completely active and did not show the presence of highly radioactive byproducts which have been observed in earlier studies of the Wilzbach labeling of proteins.     

Design of a New Peptide Substrate Probe of the Putative Biomarker Legumain with Potential Application in Prostate Cancer Diagnosis Ex Vivo

International Journal of Peptide Research and Therapeutics - The lysosomal endoprotease legumain (asparaginyl endoprotease) has been proposed as a putative biomarker in prostate tumours, in which...