Intracellular enzymes of collagen biosynthesis in rat liver as a function of age and in hepatic injury induced by dimethylnitrosamine. Changes in prolyl hydroxylase, lysyl hydroxylase, collagen galactosyltransferase and collagen glucosyltransferase activities.

The relationship between the changes in the four enzyme activities catalysing intracellular post-translational modifications in collagen biosynthesis were studied in rat liver as a function of age and in experimental hepatic injury induced by the administration of dimethylnitrosamine. During aging, relatively large changes were found in prolyl hydroxylase and lysyl hydroxylase activities, whereas only minor changes took place in collagen galactosyltransferase and collagen glucosyltransferase activities. In hepatic injury, the two hydroxylase activities increased earlier and to a larger extent than did the two glycosyltransferase activities, and the largest was found in lysyl hydroxylase activity. The data support previous suggestions that changes in the rate of collagen biosynthesis in the liver cannot be explained simply by a change in the number of collagen-producing cells, but regulation of the enzyme activities existed, so that the two hydroxylase activities altered considerably more than did the two collagen glycosyltransferase activities.     

A histochemical study about changes in rat liver plasma membrane enzyme activities after galactosamine administration.

In rats changes in plasma membrane enzyme activities due to Gal-N intoxication were studied by enzymehistochemical methods. The bile canalicular 5'-nucleotidase and nucleoside polyphosphatase activities decreased; the sinusoidal 5'-nucleotidase remained unchanged. The bile canalicular leucyl-beta-naphthyl-amidase showed an increase in activity; the alkaline phosphatase activity remained unchanged. In contrast to the spotty necrosis, changes in plasma membrane enzyme activities were seen in all liver cells, suggesting that changes of these activities, occurring after Gal-N treatment, do not correlate with cell death. The conclusion was drawn that the deviations of the enzyme activities might be due to changes in the lipid environment of the enzyme proteins in the membrane. With the exception of alkaline phosphatase, partial hepatectomy caused the same changes in enzyme activities as did Gal-N intoxication. Nevertheless Gal-N administration to partial hepatectomized rats did not lead to hepatic necrosis. Galactose given simultaneously or within two hours after Gal-N prevented both changes in plasma membrane enzyme activities and hepatocellular damage. This suggests an important role of galactolipids and galactoproteins in the plasma membrane alterations.     

Disaccharidase activities in pregnant and lactating rats

The changes in intestinal disaccharidase activities in pregnancy and lactation could be explained as a result of an adaptation to the energy demands of each reproductive stage. To examine these changes, disaccharidase activities (lactase, sucrase, maltase, and trehalase) were measured in the jejunum and ileum of virgin, pregnant and lactating Wistar rats. Minor changes in disaccharidase activities were observed in pregnancy, whereas an increase of disaccharidase activities per small intestine length normalized to body mass was observed in lactation.     

海水型呼吸窘迫综合征兔肺酶活性定位和图像分析

采用酶活性反应的图像分析和细胞化学技术,对兔海水型呼吸窘迫综合征(SW-RDS)肺酶活性的变化进行了研究。SW-RDS组肺碱性磷酸酶、5-核苷酸酶、对-硝基苯磷酸酶和细胞色素氧化酶活性明显下降,而胞嘧啶单核苷酸酶活性明显增强。这表明肺一些酶活性的改变是SW-RDS发病机理之一。     

Mechanism of bronchodilator effect in chronic airflow limitation.

OBJECTIVE: To examine the mechanisms through which two bronchodilators (theophylline and salbutamol) influence dyspnea during daily activities. METHODS: Twenty-four patients with chronic airflow limitation participated in a multiple crossover, randomized, placebo-controlled trial. The effect of theophylline and salbutamol, alone or combined, on pulmonary function and dyspnea during daily activities was examined. Correlations of changes in forced expiratory volume in 1 second (FEV1) and maximum expiratory pressures (MIPs) (independent variables) and changes in dyspnea score during daily activities (dependent variable) were also examined. RESULTS: The two drugs proved to be beneficial the effects in general were additive rather than synergistic. The drugs improved the FEV1; theophylline significantly improved the MIPs. The correlation between the changes in FEV1 and those in dyspnea score, after adjustment for the changes in MIPs, was 0.55 (p less than 0.001). The correlation between the changes in MIPs and those in dyspnea score, after adjustment for the changes in FEV1, was 0.39 (p less than 0.001). CONCLUSIONS: Changes in airway calibre and in respiratory muscle strength play an independent and important role in dyspnea during daily activities in patients with chronic airflow limitation. Changes in airway calibre may be of greater importance.     

Glycosidase activity in phenotypically different pathologic lymphoid cells, found at various stages of differentiation

The activities of seven glycosidases (six lysosomal and one cytosolic) were determined in B- and T-lymphoid cells differing by immunological phenotypes and occurring at various differentiation stages. The cells were isolated from the circulating blood, bone marrow or spleens of patients with various forms of lymphoproliferative disorders. The glycosidase activities varied significantly depending on the phenotype. The highest activity of all glycosidases was observed in cells with a common lymphoid cell progenitor phenotype. In cells having the phenotype of mature T- and B-cells the glycosidase activities were comparatively low. The changes in all glycosidase activities depending on the phenotype and differentiation stage usually occurred in the same direction; however, the degree of elevation or decline of activities of individual glycosidases was different. The activities of N-acetyl-beta-D-hexosaminidase and alpha-D-mannosidase changed dramatically, whereas the changes in the activity of cytosolic neutral alpha-D-glucosidase were less apparent. These data suggest that lysosomal glycosidases play specific roles in lymphoid cell differentiation.     

Nonstructural carbohydrate metabolism during leaf ageing in tobacco (Nicotiana tabacum)

Nonstructural carbohydrate status and activities of ADP-glucose pyrophosphorylase (EC 2.7.7.27, ADPG pyrophosphorylase) and sucrose phosphate synthase (EC 2.4.1.14, SPS) were determined during ageing of tobacco ( Nicotiana tabacum L., cvs KY 14 and Speight G28) leaves sampled from control plants and from plants that had the apical meristem and subsequent axillary growth removed (detopped plants). Over the 30-day period shoot growth increased much more for control compared to detopped plants, but the increase in root growth was similar for both treatments. Dry matter and leaf area of the individual leaf used for enzyme and metabolite analysis were constant over time for controls but increased 5-fold for detopped plants. Ageing of control leaves was indicated by a progressive loss of chlorophyll and ribulose 1, 5-bisphosphate carboxylase (EC 4.1.1.39, Rubisco) activity; loss of these components was diminished for detopped plants. In contrast to chlorophyll and Rubisco activity, activities of ADPG pyrophosphorylase and SPS remained relatively constant over time for controls. Thus, under normal ageing conditions, changes in activities of ADPG pyrophosphorylase and SPS were not closely associated with changes in the standard senescence indicators chlorophyll and Rubisco activity. The activities of ADPG pyrophosphorylase and SPS were enhanced, relative to controls, within 6 days after applying the detopping treatment and activities remained high for the duration of the 30-day period. Detopping also led to increased concentrations of starch and sucrose, but the increases were not well correlated with changes in enzyme activities. The data indicated that the leaves of detopped plants functioned as both source leaves, with enhanced ability to synthesize carbohydrate, and sink leaves, with enhanced growth. Therefore, activities of ADPG pyrophosphorylase and SPS were more responsive to changes within an individual leaf than to changes in whole plant growth.     

Fatty acid desaturase activities are modulated by phytosterol incorporation in microsomes

The effect of phytosterol-rich diets (3% beta-sitosterol + 2% campesterol) on rat liver microsomal fatty acid desaturases, membrane dynamics and lipid composition was investigated. After a 21 day period, phytosterol was incorporated into microsomes and the membrane fluidity decreased. There were no changes in either the phospholipid composition or in the total sterol content. However, the phytosterol/cholesterol ratio increased. In the animals fed phytosterols, the delta 5-, delta 6- and delta 9-fatty acid desaturases were significantly more active than in control animals. The changes in the lipid fatty acid composition were consistent with those of the desaturase activities. Hence, it is suggested that: (1) dietary phytosterol modulates desaturase activities; (2) phytosterols make the membrane more rigid but do not induce changes in the relative phospholipid composition; (3) delta 9-, delta 5- and delta 6-desaturase activities increase when the membrane becomes more rigid without changes in the phospholipid composition.     

Energy metabolism in developing Ascaris lumbricoides eggs. I. The glycolytic enzymes.

The changes in the activities of the glycolytic enzymes were followed during the development of Ascaris lumbricoides eggs. The maximum catalytic capacities of the major catabolic pathways were estimated from the maximum activities of the nonequilibrium enzymes, and the results are compared with the changes in metabolic rate and the changes in carbohydrate and lipid utilization which occur during development. Although the onset of carbohydrate and lipid utilization was accompanied by an increase in the catalytic capacities of the corresponding pathways, there was no drop in the catalytic capacities of the pathways when the eggs became dormant, nor was there any change when the dormant egg was activited.     

Changes in enzyme activities in tissues of rats exposed to hypoxia (Short Communication)

Rats were exposed to various degrees of hypoxia and enzyme activities in their tissues were determined. In general, oxidative metabolism was not increased in response to hypoxia, nor was anaerobic metabolism. Physiological and anatomical changes were concluded to be more important than changes in cellular enzyme activities in the overall adaptation to acute hypoxia.     

Age-dependent changes in glucose 1,6-bisphosphate levels and in the activities of glucose 1,6-bisphosphatase, and particulate hexokinase and 6-phosphogluconate dehydrogenase in rat skin

The levels of glucose 1,6-bisphosphate (Glc-1,6-P2), the powerful regulator of carbohydrate metabolism, changed in rat skin during growth: Glc-1,6-P2 increased during the first week of age, and thereafter was dramatically reduced during maturation. The activity of glucose 1,6-bisphosphatase, the enzyme that degradates Glc-1,6-P2, changed with age in an invert manner as compared to the changes in Glc-1,6-P2. These findings suggest that the age dependent changes in this enzyme's activity may account for the changes in intracellular Glc-1,6-P2 concentration. The age-related changes in Glc-1,6-P2 were accompanied by concomitant changes in the activities of particulate (mitochondrial) hexokinase and 6-phosphogluconate dehydrogenase, the two enzymes known to be inhibited by Glc-1,6-P2. The activities of both these enzymes in the soluble fraction were not changed with age. The particulate enzymes were more susceptible to inhibition by Glc-1,6-P2 than the soluble activities, which may explain why only the particulate, but not the soluble activities, correlated with the age-dependent changes in tissue Glc-1,6-P2. These results suggest that the changes in particulate hexokinase and 6-phosphogluconate dehydrogenase resulted from changes in intracellular concentration of Glc-1,6-P2. The marked reduction in Glc-1,6-P2 during maturation, accompanied by activation of mitochondrial hexokinase and 6-phosphogluconate dehydrogenase, may reflect an enhancement in skin metabolism during growth.     

A histochemical study about changes in rat liver plasma membrane enzyme activities after galactosamine administration

Summary In rats changes in plasma membrane enzyme activities due to Gal-N intoxication were studied by enzymehistochemical methods. The bile canalicular 5-nucleotidase and nucleoside polyphosphatase activities decreased; the sinusoidal 5-nucleotidase remained unchanged. The bile canalicular leucyl--naphthyl-amindase showed an increase in activity; the alkaline phosphatase activity remained unchanged. In contrast to the spotty necrosis, changes in plasma membrane enzyme activities were seen in all liver cells, suggesting that changes of these activities, occurring after Gal-N treatment, do not correlate with cell death. The conclusion was drawn that the deviations of the enzyme activities might be due to changes in the lipid environment of the enzyme proteins in the membrane.With the exception of alkaline phosphatase, partial hepatectomy caused the same changes in enzyme activities as did Gal-N intoxication. Nevertheless Gal-N administration to partial hepatectomized rats did not lead to hepatic necrosis. Galactose given simultaneously or within two hours after Gal-N prevented both changes in plasma membrane enzyme activities and hepatocellular damage. This suggests an important role of galactolipids and galactoproteins in the plasma membrane alterations.Dedicated to Prof. Dr. E. Havinga on the occasion of his 70th birthday     

Changing motor patterns of the 3rd axillary muscle activities associated with longitudinal control in freely flying hawkmoths

The 3rd axillary muscles (3AXMs) in the mesothorax in hawkmoths are direct flight muscles and pull forewings back along to the body axis. The 3AXMs are regarded as steering muscles because of their changeable activities during turning flight under tethered conditions. We investigated activities of the upper unit of the 3AXMs during free flight with a micro-telemetry device and captured body and wing movements by high-speed cameras. The 3AXM was activated with 1 to 3 spikes per each wingbeat cycle but sometimes ceased to fire. The phase of the onset of the activities was, even though it was variable, close to the phase of the elevator muscle activities. Therefore the upper unit of the 3AXM activities would affect upstroke properties phasically including wing retractions. We focused on longitudinal flight control and identified a correlation between the phase of the 3AXM and body pitch angle, which is important kinematical parameter for longitudinal control in insect flight. The phasic changes of the 3AXM activities would support quick changes in longitudinal control.     

Precocious alteration of digestive enzyme activities in small intestine and pancreas by chronic oral administration of protease inhibitor in suckling rats.

1. The role of endogenous CCK in the development of digestive enzyme activities in small intestine and pancreas was investigated in suckling rats. Synthetic protease inhibitor (camostat 100 micrograms/g bwt) was orally administered twice daily for 5 days from 11 days of age. 2. Pancreatic hypertrophy and hyperplasia, and alteration of pancreatic enzyme composition, especially decreases in amylase activity and increases in trypsin and chymotrypsin activities were produced by camostat treatment. These changes were completely suppressed by simultaneous administration of the potent CCK receptor antagonist L-364,718 (1 microgram/g bwt). 3. With camostat treatment, intestinal lactase activity decreased to 41%, while maltase and sucrase activities increased 3 and 2.5 times respectively. These changes in enzyme activities were not affected by the application of L-364,718. 4. The mucosal disaccharidase and pancreatic enzyme activities could not be modified by chronic subcutaneous injection of camostat. The precocious induction of maltase and sucrase activities by camostat treatment was also observed in the adrenalectomized pups. 5. These results indicate that pancreatic growth accompanied by alteration of digestive enzyme composition in the suckling rats is regulated by endogenous CCK, but the precocious induction of disaccharidase activities is not mediated by endogenous CCK released by camostat treatment.     

Kinetic and circular dichroism studies of enzymes adsorbed on ultrafine silica particles

Negatively charged ultrafine silica particles (average diameter 20 nm) were used as support materials for adsorption immobilization of porcine trypsin, horseradish peroxidase, and bovine catalase under various conditions, and the changes in the enzyme activities and the circular dichroism (CD) spectra of these enzymes upon adsorption were measured. Since the light scattering intensity of the ultrafine particles was very low, the activities and the CD spectra of the enzymes adsorbed on the particle surfaces could be measured. The enzymes adsorbed at pH around and above their isoelectric points (pI) showed high activities. On the other hand, the enzymes adsorbed at pHs below their pI had significantly diminished activities and showed large CD spectral changes upon adsorption. The extent of CD spectral changes in the enzymes upon adsorption correlated very closely with that of the activity reduction. Therefore, the conformational changes in enzymes upon adsorption are one of the important factors that reduce the activities of adsorbed enzymes. These results demonstrate that the ultrafine particles are not only a novel support for enzyme immobilization but also are helpful for the molecular understanding of the immobilized enzymes. Correspondence to: A. Kondo     

Maximal activities of enzymes involved in adenosine metabolism in muscle and adipose tissue of rats under conditions of variations in insulin sensitivity

The maximal activities of 5'-nucleotidase, adenosine deaminase and adenosine kinase were measured in quadriceps or soleus muscle from animals in which the sensitivity to insulin was changed. Most conditions caused no effect on the activities but exercise-training increased the activity of adenosine deaminase and cold exposure increased the activity of 5'-nucleotidase in soleus muscle: in addition, ageing decreased markedly the activities of all three enzymes in both muscles. When the activities are based on mg protein they are much higher in both white and brown adipose tissue than in muscle, suggesting that changes in adenosine concentration may be important in changing insulin sensitivity in adipose tissue whereas changes in adenosine receptor number may be more important in muscle.     

Effect of cholinergic drugs on the activity of basic carboxypeptidases in rat nervous tissue

Effects of a single administration of cholinergic drugs (arecoline, atropine, nicotine, mecamylamine) on the activity of carboxypeptidase H and of phenylmethylsulfonyl fluoride-inhibited carboxypeptidase, which are involved in metabolism of neuropeptides, were studied in brain parts and the adrenal glands of rats. The enzyme activities were determined fluorimetrically using specific inhibitors and substrates. In the majority of cases the enzyme activities decreased, and this decrease was retained for at least 72 h. Changes in the activities of the studied enzymes depended on the type of cholinergic action, the nervous system part, and the time after the injection. The changes in activities of the studied carboxypeptidases are supposed to be a possible mechanism responsible for changes in the levels of neuropeptides under the influence of high doses of the drugs.     

基于Budyko假设的渭河径流变化归因识别

定量评价河川径流量变化特征,开展其归因识别研究是制定气候变化应对策略与合理利用水资源的基础。以渭河流域为研究区,采用Mann-Kendall趋势检验法、双累积曲线等方法分析渭河流域1958—2015年的气候、水文要素变化特征,采用基于Budyko水热耦合平衡理论的水量平衡法估算径流变化对各驱动因素的弹性系数,定量评价气候变化和人类活动对径流变化的贡献率。结果表明:渭河流域咸阳、张家山、状头站的年径流量呈显著减少趋势,径流深减少速率分别为:-1.520、-0.501、-0.322 mm/a。3个站控制流域面平均降雨量呈非显著性减少趋势,年潜在蒸散发呈非显著增加趋势。剧烈的人类活动如工农业用水、大规模水土保持措施的实施及退耕还林草等引起的下垫面变化是径流量减少的主要因素,渭河干流和泾河流域下垫面变化对径流减少的贡献率均超过了60%,降雨变化贡献次之,潜在蒸散发的影响最小。     

Effects of the activities of key enzymes involved in starch biosynthesis on the fine structure of amylopectin in developing rice (Oryza sativa L.) endosperms

The dynamic changes of the activities of enzymes involving in starch biosynthesis, including ADP-glucose pyrophosphorylase (AGPase), soluble starch synthases (SSS), starch branching enzyme (SBE) and starch debranching enzymes (DBE) were studied, and changes of fine structure of amy- lopectin were characterized by isoamylase treatment during rice grain development, using trans anti-waxy gene rice plants. The relationships between the activities of those key enzymes were also analyzed. The amylose synthesis was significantly inhibited in transgenic Wanjing 9522, but the total starch content and final grain weight were less affected as compared with those of non-transgenic Wanjing 9522 rice cultivar. Analyses on the changes of activities of enzymes involving in starch bio- synthesis showed that different enzyme activities were expressed differently during rice endosperm development. Soluble starch synthase is relatively highly expressed in earlier stage of endosperm de- velopment, whilst maximal expression of granule-bound starch synthase (GBSS) occurred in mid-stage of endosperm development. No obvious differences in changes of the activities of AGPase and SBE between two rice cultivars investigated, except the DBEs. Distribution patterns of branches of amy- lopectin changed continually during the development of rice grains and varied between two rice culti- vars. It was suggested that amylopectin synthesis be prior to the synthesis of amylose and different enzymes have different roles in controlling syntheses of branches of amylopectin.