Neuroregulation of nonexercise activity thermogenesis and obesity resistance

High levels of spontaneous physical activity in lean people and the nonexercise activity thermogenesis (NEAT) derived from that activity appear to protect lean people from obesity during caloric challenge, while obesity in humans is characterized by dramatically reduced spontaneous physical activity. We have similarly demonstrated that obesity-resistant rats have significantly greater spontaneous physical activity than obesity-prone rats, and that spontaneous physical activity predicts body weight gain. Although the energetic cost of activity varies between types of activity and may be regulated, individual level of spontaneous physical activity is important in determining propensity for obesity. We review the current status of knowledge about the brain mechanisms involved in controlling the level of spontaneous physical activity and the NEAT so generated. Focus is on potential neural mediators of spontaneous physical activity and NEAT, including orexin A (also known as hypocretin 1), agouti-related protein, ghrelin, and neuromedin U, in addition to brief mention of neuropeptide Y, corticotrophin releasing hormone, cholecystokinin, estrogen, leptin, and dopamine effects on spontaneous physical activity. We further review evidence that strain differences in orexin stimulation pathways for spontaneous physical activity and NEAT appear to track with the body weight phenotype, thus providing a potential mechanistic explanation for reduced activity and weight gain.     

Variations in enzyme activity in stomach and pancreatic tissue and digesta in piglets around weaning

A study was performed to investigate the effect of weaning at 4 weeks of age on the activity of digestive enzymes in the stomach and pancreatic tissue and in digesta from 3 days prior to weaning to 9 days postweaning in 64 piglets. In stomach tissue the activity of pepsin and gastric lipase was determined. Pepsin activity declined abruptly after weaning but 5 days postweaning the weaning level was regained and in the gastric contents no change in pepsin activity was observed. Weaning did not influence the activity of gastric lipase. The activity of eight enzymes and a cofactor was measured in pancreatic tissue. The effect of weaning on the enzyme activity was highly significant for all enzymes except elastase. The activity of all enzymes remained at the weaning level during day 1–2 postweaning followed by a reduction of the activity. The activity of trypsin, carboxypeptidase A, amylase and lipase exhibited minimum activity 5 days postweaning. Trypsin activity increased to the preweaning level on day 7–9 whereas the activity of the others increased but did not reach the preweaning level. The activity of chymotrypsin, carboxypeptidase B and carboxyl ester hydrolase decreased during the entire experimental period. In digesta no effect of weaning was observed on the activity of amylase and trypsin. The activity of chymotrypsin was reduced after weaning in the proximal third of the small intestine and lipase and carboxyl ester hydrolase activity was reduced in the middle and distal parts of the small intestine after weaning. The present study shows that the activities of the digestive enzymes in the pancreatic tissue are affected by weaning. Even though the pancreatic secretion cannot be judged from these results they show that the enzymes respond differently to weaning. In general the activity of the digestive enzymes in pancreatic tissue is low on day 5 postweaning which in interaction with other factors may increase the risk of developing postweaning diarrhoea.     

Role of Ca2+-dependent metalloprotease-2 in stimulating Ca2+ ATPase activity under peroxynitrite treatment in bovine pulmonary artery smooth muscle membrane

We have determined effect of the oxidant peroxynitrite (ONOO-) on Ca2+-dependent matrix metalloprotease-2 (MMP-2) activity and the role of the protease on Ca2+ ATPase activity in bovine pulmonary vascular smooth muscle plasma membrane under ONOO- -triggered conditions. The smooth muscle plasma membrane possesses a 72-kDa protease activity in a gelatin-containing zymogram. The 72-kDa protease activity has been found to be inhibited by tissue inhibitor of metalloprotease-2 (TIMP-2), indicating that the protease is the matrix metalloprotease-2 (MMP-2). Treatment of the membrane suspension with ONOO- caused stimulation of the MMP-2 activity (as evidenced by 14C-gelatin degradation) and also increased Ca2+ ATPase activity. The ONOO- -triggered protease activity and the Ca2+ ATPase activity were found to be inhibited by the antioxidants: vitamin E, thiourea, and mannitol. Pretreatment with catalase and superoxide dismutase did not significantly alter ONOO- -stimulated MMP-2 activity and Ca2+ATPase activity, indicating that peroxide and superoxide are not present in appreciable amount in ONOO-. Under both basal and ONOO- triggered conditions, the MMP-2 activity and the Ca2+ ATPase activity were also inhibited by EGTA, 1:10-phenanthroline, and TIMP-2. However, the ONOO- -stimulated MMP-2 activity and the Ca2+ ATPase activity were found to be insensitive to phenylmethylsulfonylfluoride, Bowman-Birk inhibitor, chymostatin, leupeptin, antipain, N-ethylmaleimide, and pepstatin. These results suggest that ONOO- caused stimulation of MMP-2 activity and that the increased MMP-2 activity subsequently played a pivotal role in stimulating Ca2+ ATPase activity in bovine pulmonary vascular smooth muscle plasma membrane.     

Mutational analysis of the superantigen staphylococcal exfoliative toxin A (ETA)

Exfoliative toxin A (ETA) is known to be a causative agent of staphylococcal scalded skin syndrome (SSSS). Although relatively little is known about exactly how the exfoliative toxins (ETs) cause SSSS, much has been discovered recently that may help elucidate the mechanism(s) by which ETA exhibits activities such as lymphocyte mitogenicity and epidermolytic activity. Here, we have shown that highly purified ETA does have T lymphocyte mitogenic activity in that wild-type ETA induced T cell proliferation whereas several single amino acid mutants lacked significant activity. Neither wild-type ETA nor any single amino acid mutants were proteolytic for a casein substrate, yet esterase activity was detected in wild-type ETA and several mutants, but eliminated in other mutants. A mutation in aa 164 (Asp to Ala) showed a 9-fold increase in esterase activity as well. Finally, we correlated esterase activity with epidermolytic activity. All mutants that lost esterase activity also lost epidermolytic activity. Conversely, mutants that retained esterase activity also retained exfoliative activity, implicating serine protease or serine protease-like activity in the causation of SSSS. Moreover, the mutants that displayed markedly reduced T cell superantigenic activity retained their epidermolytic activity (although some of these mutants required higher doses of toxin to cause disease), which suggests an ancillary role for this activity in SSSS causation.     

Protocollagen proline hydroxylase in skin and muscle of some vertebrate species

Protocollagen proline hydroxylase activity was studied in skin and muscle of poikilothermic and homoiothermic animals. Lower PPH activity was found in the former than in the latter. Increased PPH activity was found in skin of young Gallus domesticus and Rattus norvegicus. In specialized skin under hormonal control, i.e. comb and wattles, increased activity in relation to sexual maturation was shown. The PPH activity in muscles of poikilotherms was lower than in those of homoiotherms. Some of the muscles had a considerable enzymatic activity. A decreasing PPH activity was noticed in birds and mammals with age. Heart muscle had more hydroxylating activity than skeletal muscle.     

Melatonin and locomotor activity in the fiddler crab Uca pugilator

The influence of melatonin on locomotor activity levels was measured in the fiddler crab Uca pugilator. First, activity in untreated, laboratory-acclimated crabs was measured over 48 hours in a 12L:12D photoperiod; this study showed a nocturnal increase in activity. In eyestalk-ablated crabs, overall activity was significantly reduced, and no significant activity pattern occurred. Next, crabs were injected with melatonin or saline (controls) at various times during the 12L:12D photoperiod (0900h, 1200h, and twice at 2100h; each trial was separated by 3-4 days) and monitored for 3 hr post-injection. Control crabs had low activity during early photophase, high at mid-photophase, increasing activity during the first scotophase trial, and decreasing activity during the second scotophase trial. Melatonin had no significant influence on activity when injected during the early-photophase activity trough or early-scotophase activity decline, but significantly increased activity when injected during the mid-photophase activity peak and early-scotophase activity incline. Next, crabs were injected during an early scotophase activity trough and monitored throughout the twelve-hour scotophase. Melatonin did not increase activity until the mid-scotophase activity increase, approximately 6 hours later, showing that the pharmacological dosage persisted in the crabs' systems and had later effects during the incline and peak of activity but not the trough. Eyestalk-ablated crabs were injected with melatonin or saline during early photo- and scotophase. Melatonin significantly increased activity in the photophase but not the scotophase trial, indicating that the responsiveness to melatonin continues following eyestalk removal, but the timing may not match that of intact crabs. Melatonin may be involved in the transmission of environmental timing information from the eyestalks to locomotor centers in U. pugilator.     

Variations in enzyme activity in stomach and pancreatic tissue and digesta in piglets around weaning

A study was performed to investigate the effect of weaning at 4 weeks of age on the activity of digestive enzymes in the stomach and pancreatic tissue and in digesta from 3 days prior to weaning to 9 days postweaning in 64 piglets. In stomach tissue the activity of pepsin and gastric lipase was determined. Pepsin activity declined abruptly after weaning but 5 days postweaning the weaning level was regained and in the gastric contents no change in pepsin activity was observed. Weaning did not influence the activity of gastric lipase. The activity of eight enzymes and a cofactor was measured in pancreatic tissue. The effect of weaning on the enzyme activity was highly significant for all enzymes except elastase. The activity of all enzymes remained at the weaning level during day 1-2 postweaning followed by a reduction of the activity. The activity of trypsin, carboxypeptidase A, amylase and lipase exhibited minimum activity 5 days postweaning. Trypsin activity increased to the preweaning level on day 7-9 whereas the activity of the others increased but did not reach the preweaning level. The activity of chymotrypsin, carboxypeptidase B and carboxyl ester hydrolase decreased during the entire experimental period. In digesta no effect of weaning was observed on the activity of amylase and trypsin. The activity of chymotrypsin was reduced after weaning in the proximal third of the small intestine and lipase and carboxyl ester hydrolase activity was reduced in the middle and distal parts of the small intestine after weaning. The present study shows that the activities of the digestive enzymes in the pancreatic tissue are affected by weaning. Even though the pancreatic secretion cannot be judged from these results they show that the enzymes respond differently to weaning. In general the activity of the digestive enzymes in pancreatic tissue is low on day 5 postweaning which in interaction with other factors may increase the risk of developing postweaning diarrhoea.     

Metabolism of glycerate-2,3-P2--II. Enzymes involved in the glycerate-2,3-P2 metabolism in chicken skeletal muscle

1. Four enzyme fractions which may be involved in the synthesis and breakdown of glycerate-2,3-P2 have been isolated from extracted skeletal muscle by gel-filtration and ion-exchange chromatography. 2. One of the fractions, corresponding to the glycerate-2,3-P2 dependent phosphoglycerate mutase, has been purified to homogeneity. In addition to the main enzymatic activity, it shows intrinsic glycerate-2,3-P2 synthase activity and glycerate-2,3-P2 phosphatase activity stimulable by glycolate-2-P. Its synthase activity represents about 10% of the total synthase activity of the tissue, and its phosphatase activity corresponds to about 60% of the total phosphatase activity. 3. Two of the fractions have glycerate-2,3-P2 synthase, glycerate-2,3-P2 phosphatase and phosphoglycerate mutase activities in a ratio similar to that of the glycerate-2,3-P2 synthase described in mammalian skeletal muscle. Their synthase activity corresponds to about 90% of the total synthase activity, and their phosphatase activity represents about 1% of the total phosphatase activity of the tissue. 4. The fourth fraction shows only glycerate-2,3-P2 phosphatase activity and represents about 40% of the total activity of the tissue. 5. It is suggested that in chicken skeletal muscle the metabolism of the glycerate-2,3-P2 is regulated in a way similar to that described in mammalian skeletal muscle.     

Correlation of immunomodulatory and therapeutic activities of interferon and interferon inducers in metastatic disease

The mechanism of therapeutic activity of recombinant murine interferon-gamma (rMu IFN-gamma) and the IFN inducer polyinosinic-polycytidylic acid solubilized with poly-L-lysine in carboxy methyl cellulose (pICLC) in treating metastatic disease was investigated by comparing effector cell augmentation with therapeutic activity in mice bearing experimental lung metastases (B16-BL6 melanoma). Effector cell functions in spleen, peripheral blood, and lung (the organ with tumor) were tested after 1 and 3 weeks of rMu IFN-gamma or pICLC administration (intravenous, three times a week). In these studies, natural killer (NK), lymphokine-activated killer (LAK), cytolytic T lymphocytes (CTL) (against specific and nonspecific targets), and macrophage tumoricidal and tumoristatic activities were measured. rM IFN-gamma and pICLC had therapeutic activity and immunomodulatory activity in most assays of immune function examined. Specific CTL activity of pulmonary parenchymal mononuclear cells (PPMC), but not in splenocytes or peripheral blood lymphocytes (PBL), during week 3 and not during week 1, correlated with the therapeutic activity of rMu IFN-gamma and of pICLC. Macrophage tumoricidal activity in PPMC, but not in alveolar macrophages, also correlated with the therapeutic activity of rMu IFN-gamma, but the opposite was true for the therapeutic activity of pICLC. NK activity of PPMC, but not of splenocytes or PBL, during week 1 correlated with the therapeutic activity of pICLC; in contrast, NK activity at any site did not correlate with the therapeutic activity of rMu IFN-gamma. LAK activity at any site did not correlate with the therapeutic activity of either agent.     

Changes in activity levels of glutamate dehydrogenase and two transaminases of maternal liver during reproduction and after administration of oestradiol and progesterone in Zoarces viviparus (L.)

The enzyme activity per unit liver wet weight, the specific activity and the total liver activity level of glutamate dehydrogenase (GDH) and two transaminases (GOT and GPT) were studied during vitellogenesis and pregnancy. A steady level of activity was observed during the short summer vitellogenesis and during early pregnancy. During mid-term pregnancy in October the activity level significantly increased.
Administration of 5 and 100 μg oestradiol increased serum vitellogenin, total liver protein and the liver somatic index during late pregnancy. Oestradiol decreased activity and specific activity of the enzymes. However, expressing activity as total hepatic enzyme activity units in fish of standard body weight oestradiol had no effect.     

Locomotor activity of atlantic salmon parr (Salmo salar L.) in various light conditions and in weak magnetic fields

Locomotor activity studies in the laboratory under artificial light cycles co-ordinated with times of sunrise and sunset demonstrated that ten of sixteen Atlantic salmon parr were nocturnal, with an approximately twenty-four hour periodicity. The remaining six fish exhibited diurnal activity patterns or activity mainly after times of light change. Two fish immediately shifted their activity patterns to co-ordinate with a 6-hr shifted light cycle. Six fish retained no activity patterns in constant light, and only two of eleven fish had weak activity patterns in constant darkness. Results suggest that Atlantic salmon parr are dependent on a light-dark cycle for timing their activity rhythms. Three of twelve salmon in an imposed magnetic field four times the strength of the horizontal vector of the ambient field, increased their activity level and changed activity patterns in the increased field. The remaining fish showed no distinct change in locomotor activity.     

三峡库区马尾松林土壤-凋落物层酶活性对凋落物分解的影响

凋落物的彻底降解是在凋落物和土壤酶系统的综合作用下完成,酶活性的提高有利于凋落物-土壤有机物质的分解和养分释放。通过对三峡库区30年生马尾松林凋落物分解、凋落物-土壤层酶活性季节动态及其对分解的影响进行研究,结果表明:30年生马尾松林凋落物经过540 d的分解后干重剩余率是59.80%;凋落物层酶活性季节动态明显,氧化还原酶活性均是11月最低,3月最高;土壤过氧化物酶活性季节变化显著且均是11月最低,多酚氧化酶活性9月较高,而过氧化物酶活性则是6月较高。马尾松林凋落物层酶活性与土壤层酶活性差异较大,且水解酶活性差异较氧化还原酶活性差异大,凋落物层脲酶活性、纤维素酶活性和蔗糖酶活性11月、6月、9月分别是0—5 cm土壤层的6.33倍、3.24倍、10.29倍,68.14倍、16.16倍、24.81倍,25.07倍、31.88倍、29.20倍。凋落物分解速率均与土壤、凋落物层氧化还原酶活性呈极显著"S"形曲线,与凋落物层水解酶活性呈二次函数关系,与土壤层水解酶均呈极显著的线性关系。凋落物质量能引起凋落物-土壤层酶活性变化,酶活性的改变反过来影响凋落物的分解,因此,凋落物-土壤层酶活性差异与凋落物分解阶段和对共同影响因素(凋落物质量、土壤温度、水分含量和土壤养分等)的敏感性不同有关,凋落物-土壤层酶的相互作用共同影响森林生态系统的物质循环和养分循环过程。     

Elevation of histidine decarboxylase activity in skeletal muscles and stomach in mice by stress and exercise

The effects of different types of stress (water bathing, cold, restraint, and prolonged walking) on histidine decarboxylase (HDC) activity in masseter, quadriceps femoris, and pectoralis superficial muscles, and in the stomach were examined in mice. All of these stresses elevated gastric HDC activity. Although water bathing, in which muscle activity was slight, was sufficiently stressful to produce gastric hemorrhage and to increase gastric HDC activity, it produced no detectable elevation of HDC activity in any of the muscles examined. The other stresses all elevated HDC activity in all three muscles. We devised two methods of restraint, one accompanied by mastication and the other not. The former elevated HDC activity in the masseter muscle, but the latter did not. These results suggest that 1) HDC activity in the stomach is an index of responses to stress, 2) the elevation of HDC activity in skeletal muscles during stress is induced partly or wholly by muscle activity and/or muscle tension, and 3) stress itself does not always induce an elevation of HDC activity in skeletal muscles.     

宫川蜜柑根际土壤酶活性与土壤养分含量相关性的研究

研究了不同肥力水平的宫川蜜柑根际土壤酶的活性及其与土壤农化特性的关系。结果表明 :高产园的土壤酶活性显著高于低产园的土壤酶活性。经统计分析 ,土壤酶活性与养分含量均呈极显著相关。而且酶的活性在土壤中的分布有一定的规律性。其水平分布是在树冠内半径的 4 /5处至树冠滴水线范围内 ,酶的活性最高 ,由此处向内向外酶的活性逐渐降低 ;其垂直分布是 0～ 2 0 cm土层酶的活性最高 ,随土层的加深而逐渐降低     

Spatial Heterogeneity in the Distribution of Denitrifying Bacteria Associated with Denitrification Activity Zones

Denitrifying enzyme activity (DEA) in artificially established denitrification activity zones was, on average, 3.5-fold greater than in bulk soil. Denitrifier biomass was between 1 and 4 orders of magnitude greater in activity zones. Denitrifier specific activity was lower in activity zones and more similar to specific activity values reported for pure cultures of denitrifying bacteria added to soil. Measurements of DEA and biomass carried out on a homogeneous subsample derived from a soil core containing a denitrification activity zone will overestimate the DEA and biomass of the bulk soil and underestimate the DEA and biomass of the activity zone.     

Ornithine decarboxylase activity in relation to DNA synthesis in mouse interfollicular epidermis and hair follicles.

The relationship between ornithine decarboxylase (L-ornithine carboxylyase, EC 4.1.1.17) activity and DNA synthetic activity was studied in mouse epidermis. Interfollicular epidermis and hair follicles were investigated separately. It was found that, in hair follicles, the variations of DNA replicative activity, which are reflected in the cyclic growth of hair, are paralleled by corresponding changes in ornithine decarboxylase activity. In both interfollicular epidermis and hair follicles, stimulation of DNA synthetic activity by plucking of hair induced a rapid and marked increase in ornithine decarboxylase activity. The relationship of steady-state and induced ornithine decarboxylase activity to DNA synthetic activity was compared in hair follicles and interfollicular epidermis. A correlation between the activity of this enzyme and DNA replication was found thereby in each of these tissues.     

21科41种(变种)植物叶片几丁质酶系的研究

对广州地区常见的21科41种（变种）植物叶片几丁质酶系研究的结果表明,所有受试植物都具有几丁质酶活性。几丁质酶不仅存在于被子植物的双子叶植物和单子叶植物中,而且也存在于裸子植物及蕨类植物中。几丁质酶活性及比活性均较高的有蕹菜、葱、蕨类植物、蒜、茄科植物、玉米、菜豆、番木瓜等。植物一般都具有两种几丁质酶:外切酶和内切酶。几丁质外切酶活性及比活性均较高的有蕨类植物、葱、茄科植物等。几丁质内切酶活性及比活性均较高的有蕹菜、裸子植物等。不同植物几丁质外切酶与内切酶的比例相差较大。有些植物的几丁质酶系以外切酶为主,如茄科植物、大部分豆科植物、番木瓜等;有些植物以内切酶为主,如裸子植物、伞形科植物、蕹菜等;有些植物的外切酶与内切酶含量相差不大。     

Insulin and fructose regulate malic enzyme activity by different processes

A comparison of the regulatory processes controlling hepatic malic enzyme activity following treatment of diabetic rats with insulin or with a high fructose diet demonstrated several important differences. Insulin treatment caused a 50-fold increase in activity, due to a 12-fold increase in enzyme quantity and a 4-fold increase in specific activity(units/nmol). Dietary fructose caused a 3-fold increase in enzyme activity, due to a 3-fold increase in enzyme quantity, with no change in the specific activity of the enzyme. Thus, while fructose initiated a minor increase in malic enzyme activity, insulin was more effective, causing a substantially greater increase in enzyme activity and activating a hormone specific alteration in the catalytic activity of each enzyme molecule.     

Epidermal collagenase activity and its induction by 20-hydroxyecdysone in the fiddler crab Uca pugilator

The epidermal collagenase activity and its induction by 20-hydroxyecdysone in Uca pugilator were investigated.Zymographic electrophoresis showed four bands of collagenae activity,16,19,22 and 29 kDa in molecular weight,with the former two accounting for 60% and 36%,respectively,of the total coUagenase activity. The collagenase activity varies during the molting cycle. Among the molt stages tested,Premoh Stage Do exhibited the highest epidermal coUagenase activity for both the 16 and 19 kDa isoenzymes and,as the molt stage proceeded,the enzymatic activity of these two isoenzymes decreased,with the lowest activity for both found in Premoh Stage D3-4. Injection of 20-hydroxyecdysone significantly induced the activity of the 16 kDa collagenase in the epidermis of Uca pugilator,suggesting that the activity of this isoenzyme is under molting hormone control.Although 20-hydroxyecdysone injection did not result in a statistically significant increase in the activity of the 19 kDa isocnzyme,a tendency of the induction was nonetheless demonstrated. This is the first report on epidermal collagenase activity and its induction by the molting hormone in a crustacean.