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771.
Y Koyama M Imoto M Tanaka Y Fukuda Y Miyazawa I Nakano T Ozawa 《Biochemistry international》1989,18(2):399-403
In order to elucidate the role of histamine in the liver, we studied the effect of a histamine H1-receptor antagonist on the carbohydrate and lipid metabolism in the rat liver. The administration of the H1-receptor antagonist decreased significantly the contents of glycogen and malonyl-CoA in the liver. However, it did not affect the levels of serum glucose and free fatty acid. These results suggest that histamine may play a part in the regulation of metabolism of carbohydrates and lipids in the liver. 相似文献
772.
Cytosolic adenylate kinase catalyzes the synthesis of thiamin triphosphate from thiamin diphosphate 总被引:2,自引:0,他引:2
An attempt was made to purify a porcine skeletal muscle enzyme catalyzing the formation of thiamin triphosphate (TTP) from thiamin diphosphate (TDP), requiring ATP, Mg2+ and a cofactor (creatine). As the purification proceeded, the reaction requirements for ATP and creatine were lost and then a requirement for ADP was manifested. The activity responsible for TTP synthesis from TDP, ADP, and Mg2+ was found to be copurified with adenylate kinase [EC 2.7.4.3] activity, and was finally purified to a single band on SDS-PAGE. Antiserum obtained against the purified enzyme preparation inhibited both adenylate kinase activity and the TTP-synthesizing activity to exactly the same extent. These results indicate that adenylate kinase catalyzes TTP formation from TDP in vitro. 相似文献
773.
Medullary sites of action for bombesin-induced inhibition of gastric acid secretion were investigated in urethane-anesthetized rats with gastric fistula. Unilateral microinjection of bombesin or vehicle into the dorsal vagal complex was performed using a glass micropipet and pressure ejection of 100 nl volume; gastric acid output was measured every 10 min by flushing the stomach. Microinjection of vehicle into the dorsal vagal complex did not alter gastric acid secretion (1.9 +/- mumol/10) from preinjection levels (2.9 +/- 0.8 mumol/10 min). Microinjection of the stable thyrotropin-releasing hormone (TRH) analog, RX 77368, at a 77 pmol dose into the dorsal vagal complex stimulated gastric acid secretion for 100 min with a peak response at 40 min (24.1 +/- 3.2 mumol/10 min). Concomitant microinjection of RX 77368 (77 pmol) with bombesin (0.6-6.2 pmol) into the dorsal vagal complex dose dependently inhibited by 35-86% the gastric acid response to the TRH analog. Bombesin (6.2 pmol) microinjected into the dorsal vagal complex inhibited by 17% pentagastrin infusion-induced stimulation of gastric acid secretion (13.2 +/- 0.8 mumol/10 min) whereas intracisternal injection induced a 69% inhibition of the pentagastrin response. These results demonstrate that the dorsal motor complex is a sensitive site of action for bombesin-induced inhibition of vagally stimulated gastric secretion. However, other medullary sites must be involved in mediating the inhibitory effect of intracisternal bombesin on pentagastrin-stimulated gastric acid secretion. 相似文献
774.
775.
A. de Raucourt D. Girard Y. Prigent P. Boyaval 《Applied microbiology and biotechnology》1989,30(5):528-534
Summary An off-line parameter estimation method has been developed to predict the dynamic behaviour of a continuous lactose fermentation system. The model used is an unstructured model taking into account cell growth, substrate consumption, and metabolite production (lactic acid). This method, based on the Hooke-Jeeves non-linear-programming technique, results in a good estimation of the biological parameters of the model, and so gives a better understanding of the different phenomena involved in lactose fermentation.Nomenclature
Cp, Cs, Cz, Dp, Ds, Dz
coefficients in system (A)
-
Fe
bioreactor influent flow rate (1/h)
-
I
current in the ED unit (A)
-
J
lactate flux in the ED unit (g/h)
-
Kd
mortality constant (h-1)
-
Kp
product inhibition constant (g/l)
-
Ks
strbstrate saturation constant (g/l)
-
P
0
product concentration in the bioreactor (g/l)
-
P
1
product concentration in the D tank (g/l)
-
P
0r
estimation of P
0 (g/l)
-
Q
0
retentate flow rate (UF influent) (1/h)
-
Q
1
permeate flow rate (1/h)
-
Q
22
cell bleed flow rate (1/h)
-
Q
3
recycling flow rate in the ED (influent) (1/h)
-
Se
substrate concentration in the influent (g/l)
-
S
0
supstrate concentration in the bioreactor (g/l)
-
S
1
substrate concentration in tank D (g/l)
-
S
0r
estimation of S
0 (g/l)
-
t
time (h)
-
V
0
fermentation broth volume (1)
-
V
1
tank D volume (1)
-
X
0
biomass concentration in the bioreactor (g/l)
-
Y
P/S
(=1/Y
S/P) lactic acid yield coefficient (g lactic acid/g lactose consumed)
-
Y
X/S
(=1/Y
S/X) cell yield coefficient (g cells produced/g lactose consumed)
-
Y
X/Z
(=1/Y
Z/X) second cell yield coefficient (g cells produced/g nitrogen consumed)
-
Y
x, Y
m
input mathematical parameters of the linear system (M
2)
-
Ze
nitrogen concentration in the influent (g/l)
-
Z
0
nitrogen concentration in the bioreactor (g/l)
-
Z
1
nitrogen concentration in tank D (g/l)
-
Z
0r
estimation of Z
0 (g/l)
- ,
constants of the Luedeking and Piret's model
-
specific growth rate (h-1)
- max
maximum specific growth rate (h-1) 相似文献
776.
Seven benign and four malignant mixed tumors of the salivary gland, biopsied using fine-needle aspiration, were analyzed using digital image analysis. Mean nuclear form factor, perimeter, and area were significantly increased in malignant cases. Better separation between diagnostic categories, however, was achieved by utilizing the coefficient of variation (CV) within a case rather than mean value. Form factor CV alone divided cases into nonoverlapping diagnostic categories. This quantitative analog of "pleomorphism" provided a useful marker for malignancy in mixed tumors. 相似文献
777.
Neurotensin immunoreactivity in the central nucleus of the rat amygdala: an ultrastructural approach
Neurotensin (NT) was demonstrated in the central nucleus of the rat amygdala (CNA) using a modification of the avidin-biotin complex immunohistochemical technique. Electron-dense reaction product (particles were 15-25 nm in diameter) was localized in perikarya, dendrites, axons, and axon terminals. It was found also associated with profiles of rough endoplasmic reticulum, mitochondria, microtubules, and small agranular as well as large granular vesicles. In distal dendrites, the reaction product was associated with microtubules, vesicles, and postsynaptic densities. Axon terminals of three types formed synaptic contracts with NT-immunoreactive neurons in the CNA: one was characterized by numerous round or oval agranular vesicles, the second by numerous pleomorphic vesicles, and the third by agranular vesicles that were loosely distributed and pleomorphic. All three types formed symmetric axosomatic and asymmetric axodendritic contacts. NT-immunoreactive axon terminals containing small round agranular vesicles stood out clearly from the intermingling profiles of immunonegative structures. We found numerous glomeruli, each consisting of a central NT-immunoreactive dendrite surrounded by all three types of axon terminals. We observed that some NT-immunoreactive terminals formed symmetric axoaxonal contacts with each other, providing evidence for the presence of local NT-to-NT circuits, whereas many others synapsed with axon terminals devoid of NT immunoreactivity. 相似文献
778.
C. Y. Boquien G. Corrieu M. J. Desmazeaud 《Applied microbiology and biotechnology》1989,30(4):402-407
Summary
Streptococcus cremoris AM2 is characterized by an aminopeptidase and Leuconostoc lactis CNRZ 1091 by an -galactosidase and a citrate lyase. These strains were grown in pure or mixed cultures, in presence or absence of citrate (15 mM) and at controlled or uncontrolled pH. Cell populations and the activities of the enzymes were measured during microbial growth. Linear correlations were established between the population of S. cremoris AM2 and aminopeptidase activity, and between that of L. lactis CNRZ 1091 and the activities of -galactosidase and citrate lyase. These correlations held regardless of whether the culture was pure or mixed and if the pH was controlled or not. The presence of citrate did not change citrate lyase and aminopeptidase activities, but inhibited the synthesis of the -galactosidase and not its activity. The linear relationships permit the determination of bacterial populations in less than 2 h without counting but by measuring enzyme activities. 相似文献
779.
A Jacquet T Kleinschmidt A G Schnek Y Looze G Braunitzer 《Biological chemistry Hoppe-Seyler》1989,370(5):425-434
The amino-acid sequence of chymopapain is presented. It was isolated from the latex of the fruits from the tropical species Carica papaya L. and is, besides papain and papaya proteinase omega, the third thiol proteinase from this source. The primary structure contains 218 amino-acid residues. It was deduced from sequence analysis of the native enzyme and of peptides obtained by tryptic, chymotryptic, peptic, thermolysinolytic and mild acidic hydrolysis. Out of a total of eight cysteine residues, six are involved in the formation of three disulfide bonds, the location of which has been established with the help of peptic and thermolysinolytic peptides and fragments, obtained by mild acidic hydrolysis. Chymopapain shares 126 identical amino-acid residues (58%) with papain and 141 (65%) with papaya proteinase omega, including the three disulfide bridges and the free cysteine in position 25, required for activity. Except some amino-acid residues in the substrate-binding site, all residues involved in the catalytic mechanism are conserved. The homology between papaya proteinases is discussed. 相似文献
780.
A F Bobkova A S Gol'dshte?nKaftanova E N Dobrov I G Atabekov 《Molekuliarnaia genetika, mikrobiologiia i virusologiia》1989,(2):35-41
Antigenic properties of intact potato virus X (PVX) particles and of PVX coat protein (CP) preparations were compared using different modifications of ELISA test. In the competitive ELISA test (reaction in solution) antibodies to intact virus react much stronger with PVX than with CP while antibodies to CP react much stronger with CP than with PVX. In the direct ELISA test (reaction on the solid support) the difference in reactions of antiCP antibodies with PVX and CP is eliminated while the one in reactions of antiPVX antibodies with these antigens remains. No difference was registered in reactivity of PVX absorbed directly on polystyrene or on immunoglobulin-coated wells (sandwich ELISA) to antiCP antibodies. 相似文献