Activity of serum enzymes in workers in the enzyme production industry

Unfavorable industrial factors in the production of enzyme preparations (enzyme dusts, microorganisms-producers) cause changes in the activity of a number of enzymes in workers' blood serum. Degree frequency and direction of enzyme shifts depend on the purity of enzyme preparations, degree of contact with them, workers' length of service and health status. The analysis of the obtained results enables us to recommend a determination of cholinesterase activity, acid phosphatase and lactate-dehydrogenase as indicators for a hygienic assessment of the effect of enzyme preparations and diagnosis of body pathogenic changes.     

Vitamin B6 biosynthesis and glycolate reductase in Flavobacterium sp. 238-7

An enzyme which reduces glycolate to glycolaldehyde as the first step of the biosynthesis of vitamin B6 was studied using the particulate fraction of Flavobacterium sp. 238-7, a vitamin B6 producer. The enzyme catalyzes the reduction of glycolate in the presence of NADPH, but not the oxidation of glycolaldehyde, and is designated as glycolate reductase. There is a positive correlation between the activity of the enzyme and vitamin B6 biosynthesis. The activity and the formation of the enzyme were not affected by vitamin B6. This enzyme probably plays a role in the extraordinary accumulation of vitamin B6 by the bacterium.     

Purification and characterization of methylmalonyl-CoA mutase from a methanol-utilizing bacterium,Methylobacterium extorquens NR-1

High activity (about 50 mU x mg protein(-1)) of methylmalonyl-CoA mutase (82-95% apo-enzyme) was constantly found during the cell growth of a methanol-utilizing bacterium, Methylobacterium extorquens NR-1. The apo-enzyme was purified to homogeneity and characterized. The purified enzyme was colorless. An apparent Mr of M. extorquens NR-1 enzyme was calculated to be 150,000 +/- 5,000 by Superdex 200 HR gel filtration. SDS-polyacrylamide gel electrophoresis of the purified enzyme gave two protein bands with an apparent Mr of 85.000 +/- 2,000 and 70,000 +/- 2,000, indicating that the M. extorquens NR-1 enzyme is composed of two nonidentical subunits. NH2-terminal amino acid sequences of the small and large subunits of M. extorquens NR-1 enzyme showed no significant homology to those of the enzyme from other species. Some enzymological properties of the M. extorquens NR-1 enzyme were studied.     

Dietary lipid regulates the amount and functional state of UDP-glucuronosyltransferase in rat liver.

The effect of a fat-free diet on the amount and functional state of UDP-glucuronosyltransferase was studied in rat liver microsomes. Measurements of enzyme activity showed that activity was approximately 30% lower in untreated microsomes in response to the fat-free diet as compared with the control diet. Immunoblotting with anti-UDP-glucuronosyltransferase showed approximately 200% less enzyme in rats fed the fat-free diet. A kinetic method for measuring total UDP-glucuronosyltransferase confirmed the result of the immunoblot. Thus, the total amount of enzyme declined to a greater extent than enzyme activity. Responses of the enzyme to activation by palmitoyl-lysophosphatidylcholine or UDP-N-acetyl-glucosamine suggested that rats fed the fat-free diet had a greater activity per molecule of UDP-glucuronosyltransferase than did rats fed the control diet. This result explained the relatively small decline in enzyme activity as compared with enzyme concentration in microsomes prepared from animals fed the fat-free diet. Fatty acid analysis of microsomal lipids demonstrated that the fat-free diet was associated with lower levels of arachidonic and linoleic acids and greater amounts of palmitoleic, oleic and cis-vaccenic acids.     

Dietary protein concentration regulates the mRNA expression of chicken hepatic malic enzyme

Chicken hepatic malic enzyme activity varies with dietary protein content. The mechanisms responsible for this alteration in activity are unclear. In a series of four experiments, broiler chicks were allowed free access for 1.5, 3, 6 or 24 h to a low (13 g/100 g diet), basal (22 g/100 g diet) or high (40 g/100 g diet) protein diet. The diets were isocaloric and had equal concentrations of dietary fat. Hepatic malic enzyme mRNA expression and enzyme activity as well as total liver lipid concentration were examined for each experimental duration. There were no differences in the expression of the mRNA for malic enzyme at 1.5 h, but at 3, 6 and 24 h, malic enzyme mRNA expression was significantly (P < 0.05) reduced in chicks fed the high protein diet and significantly enhanced in chicks fed the low protein diet compared with chicks fed the basal diet. Hepatic malic enzyme activities and total lipid concentration were not different among the chicks fed the different diets at 1.5 and 3 h. At 6 and 24 h, malic enzyme activity and total liver lipid concentration were both significantly greater in birds fed the low protein diet compared with levels in the birds fed the other two diets. In birds fed the high protein diet, malic enzyme activity and total liver lipid concentration were significantly reduced at 24 h compared with birds fed the basal diet. In a final experiment, the observed differences in malic enzyme mRNA expression at 6 h were confirmed when chicks were given access to isocaloric diets with the same protein levels as the initial 4 experiments, but with the dietary concentration of carbohydrate held constant. The results suggest that previously observed alterations in the activity of malic enzyme, which were correlated with dietary protein intake, are due to rapid changes in the mRNA expression of this enzyme.     

Reduction of delta-aminolevulinate dehydratase concentration by bromobenzene in rats

The effects of bromobenzene on delta-aminolevulinate (ALA) dehydratase (EC 4.2.1.24) were examined in rats. The enzyme in the bone marrow was irreversibly inhibited after 12 hours of treatment with bromobenzene (intraperitoneally) without any change in the enzyme concentration. When bromobenzene treatment was prolonged to 72 hours, the concentrations of the enzyme in the bone marrow and in the liver were reduced proportionally to the decrease in the enzyme activity. Neither the activity nor the concentration of ALA dehydratase in the peripheral erythrocytes were reduced even after 72 hours treatment with bromobenzene. These findings indicate that bromobenzene decreases ALA dehydratase activity in a biphasic manner; firstly, through an irreversible inhibition probably due to the formation of mercaptide with the essential SH groups and, secondly, through a reduced synthesis of the enzyme.     

产AmpC酶革兰阴性杆菌的分布与耐药性研究

目的了解产AmpC酶革兰阴性杆菌的分布及其耐药特征,指导临床合理使用抗菌药物. 方法采用双纸片法检测了493株革兰阴性杆菌的AmpC酶,并用仪器法测定了产酶菌对17种抗菌药物的耐药性. 结果革兰阴性杆菌产AmpC酶总阳性率为38.3%,以铜绿假单胞菌和阴沟肠杆菌为主,分别占产酶菌的54.0%和24.3%;病区分布以重症监护病房为最高(34.4%),感染部位以呼吸道多见(55.6%);产AmpC酶菌对青霉素类和一至三代头孢类抗菌药物耐药率高达37%～100%;对亚胺培南、头孢吡肟和哌拉西林/他唑巴坦的耐药率较低,在9%～28%之间;其他抗菌药物耐药率各有差异. 结论产AmpC酶革兰阴性杆菌有较严重的耐药性,合理使用抗菌药物十分重要.     

Effect of dietary protein and iron on the fractional turnover rate of rat liver xanthine oxidase

Rat liver xanthine oxidase activity is regulated in response to dietary protein and iron. To investigate whether the change in activity was mediated by a change in the rate of protein degradation, we measured the fractional turnover rate using the double-isotope technique with [3H]- and [14C]leucine and calculated the apparent half-life of xanthine oxidase in rats fed diets containing either 20 or 5% casein with either 35 or 5 mg iron/kg diet. Under control conditions, xanthine oxidase had an apparent half-life of 4.8 d and approximately 65% of the enzyme subunits were active. Rats fed diets with low dietary protein had lower xanthine oxidase activity, but the enzyme had a slower fractional turnover rate, resulting in an apparent half-life of 6.4 d, and only 15-20% of the enzyme was active. The apparent half-life of xanthine oxidase increased to 7.5 d in rats fed diets with low dietary iron, but dietary iron did not affect the specific activity of the enzyme or the percentage of active subunits. These results suggest that the loss of enzyme activity is not due to loss of enzyme protein by increased degradation, but rather to inactivation of the enzyme.     

Antagonistic effects of zinc and aluminum on lead inhibition of delta-aminolevulinic acid dehydratase

In vitro and in vivo studies regarding the influence of metals on delta-aminolevulinic acid dehydratase activity in erythrocytes indicate that a lead concentration of 4 micrometer/l completely inhibits the enzyme. Zinc activates the enzyme both in vitro and in vivo at concentrations greater than 76 micrometer/l. Aluminum has an inhibitory effect at all concentrations in vitro whereas it activates the enzyme in vivo. Zinc and aluminum together activate the enzyme in vivo. The in vitro activation of zinc is inhibited by increasing concentrations of aluminum. Aluminum and lead together depress the enzyme activity in an additive way that can be reactivated by the addition of zinc.     

Enzyme supplementation of dry and wet wheat-based feeds for broiler chickens: performance and gut responses

To test whether the improvements in digestive efficiency due to either wetting of the food or inclusion of enzymes are accompanied by the same changes in gut function, foods with a high content of wheat were fed to broiler chicks from 1-42 d old. Twenty-four birds were caged individually while a further sixty-four were in group pens in experiments of 2 x 2 factorial design with two levels of enzyme (0 or 1 g/kg, designed for wheat) and two levels of water addition (0 and 1300 g/kg). Food intake and live-weight gain were significantly increased by wet feeding (from 89.3 to 153.4 g/d and from 39.7 to 65.4 g/d respectively), the differences increasing with age, while the enzyme had no significant effect (120.5 and 122.2 g/d and 51.9 and 53.1g/week respectively). The viscosity of digesta was greatly reduced both by wetting (from 4.40 to 2.64 kPa. s) and enzyme (from 4.47 to 2.57 kPa. s) but there was a significant interaction with age in which the viscosity was low throughout in the wet only, enzyme only and wet + enzyme treatments but declined with age from a very high level in the dry, no enzyme treatment (11.5 kPa. s at 14 d). While wetting increased weight and length of digestive tract and thickness of some parts of the gut, enzyme had no significant effect, tending to reduce gut wall thickness. Crypt cell proliferation rate (CCPR) was significantly reduced by wet feeding (from 39.4 to 28.7 cells/crypt per 2 h) and by enzyme supplementation (from 38.9 to 29.2 cells/crypt per 2 h). Therefore, while both wetting and enzyme addition to the food reduced digesta viscosity and CCPR to a similar extent, the former had marked stimulatory effects on food intake and weight gain while the latter had little effect. The mode of action of wet feeding is therefore deduced to be not primarily through its effects on viscosity and CCPR.     

Atropine-nonsensitive feedback regulatory mechanism of rat pancreatic enzyme secretion in response to food protein intake

The effect of atropine on pancreatic enzyme secretion in response to removal of intraluminal protease was investigated using rats with an indwelling bile-pancreatic cannula. Stimulation of pancreatic enzyme secretion by diversion of bile-pancreatic juice was blocked by intravenous atropine [100 micrograms/(kg X h)] injection. On the other hand, stimulation of pancreatic enzyme secretion by intraluminal infusion of soybean trypsin inhibitor (SBTI) was not blocked by atropine administration. These results suggest that the feedback response of pancreatic enzyme secretion after removal of the intraluminal protease is controlled by at least two different systems, an atropine-sensitive mechanism and an atropine-nonsensitive mechanism. We detected and purified a peptide from rat bile-pancreatic juice that enhanced pancreatic enzyme secretion when the peptide was infused into the proximal intestine. In the atropine-administered rat whose small intestine was deprived of protease after intraluminal washing with saline containing SBTI, intraluminal infusion of the purified peptide stimulated pancreatic enzyme secretion markedly. These findings suggest that the atropine-nonsensitive feedback response of pancreatic enzyme secretion is at least in part mediated by the peptide.     

Reduction of delta-aminolevulinate dehydratase concentration by bromobenzene in rats.

The effects of bromobenzene on delta-aminolevulinate (ALA) dehydratase (EC 4.2.1.24) were examined in rats. The enzyme in the bone marrow was irreversibly inhibited after 12 hours of treatment with bromobenzene (intraperitoneally) without any change in the enzyme concentration. When bromobenzene treatment was prolonged to 72 hours, the concentrations of the enzyme in the bone marrow and in the liver were reduced proportionally to the decrease in the enzyme activity. Neither the activity nor the concentration of ALA dehydratase in the peripheral erythrocytes were reduced even after 72 hours treatment with bromobenzene. These findings indicate that bromobenzene decreases ALA dehydratase activity in a biphasic manner; firstly, through an irreversible inhibition probably due to the formation of mercaptide with the essential SH groups and, secondly, through a reduced synthesis of the enzyme.     

11 beta-hydroxysteroid-dehydrogenase: characteristics and the clinical significance of a key enzyme in cortisol metabolism]

The enzyme 11 beta HSD catalyzes the interconversion of the biologically active cortisol and the biologically inactive cortisone. There are two distinct isozymes: 11 beta HSD type 1 is mainly expressed in liver and is a bidirectional enzyme, with both dehydrogenase and reductase activity. 11 beta HSD type 2 is mainly expressed in kidney and is a unidirectional enzyme with only dehydrogenase activity. 11 beta HSD type 2 protects the mineralocorticoid receptor from being activated by cortisol. Thus, specificity of this receptor in vivo is enzyme and not receptor mediated. The syndrome of apparent mineralocorticoid excess is caused by a congenital deficiency of 11 beta HSD type 2. Liquorice-induced hypertension is an example of an acquired defect in dehydrogenase activity of 11 beta HSD, caused by glycyrrhetinic acid. 11 beta HSD may play a role in the pathogenesis of 'essential' hypertension, obesity and type 1 diabetes mellitus. Angiotensin-converting enzyme inhibitors enhance dehydrogenase activity of 11 beta HSD, which may contribute to their natriuretic effect.     

急性有机磷农药中毒病人的心肌酶变化

目的 探讨急性有机磷农药中毒（ＡＯＰＩ）病人心肌酶变化规律。方法 对２１７例ＡＯＰＩ病人心肌酶（ＡＳＴ、ＬＤＨ、α－ＨＢＤＨ、ＣＫ、ＣＫ－ＭＢ）进行连续监测，并观察病人心脏功能改变。结果 ＡＯＰＩ病人心肌酶均有不同程度升高，且与中毒程度呈正相关，心肌酶随病情改善呈恢复趋势。结论 心肌酶水平对ＡＯＰＩ病人具有预后作用，极度升高者，病情严重，预后不良。对重症病人应加强心脏监护，以防心源性猝死发生。     

一种酶液智能配比装置的研制

目的:研制一种酶液智能配比装置,以控制酶液配比精准度,有效避免清洗医疗器械时产生污染。方法:采用STC15F104E单片机模块,实现一键全自动配比。传感器接收信号后通过单片机控制蠕动泵通断实现酶液智能配比,蠕动泵直接蠕动液管抽取适量酶液进入清洗槽,使整个配比过程简洁和高效。结果:酶液通过流量控制单元与蠕动泵的配合实现精准控制抽取,避免了酶液的浪费。手工加酶液的量与智能配比装置加酶液的量的平均值的对比,智能配比装置酶液的控制精准度高于手工配比10%。结论:酶液智能配比装置改变以往酶洗液医疗器械清洗消毒的工作流程,实现安全高效清洗,避免污染。     

Gene identification and characterization of the pyridoxine degradative enzyme alpha-(N-acetylaminomethylene)succinic acid amidohydrolase from Mesorhizobium loti MAFF303099

We have found for the first time that a chromosomal gene, mlr6787, in Mesorhizobium loti encodes the pyridoxine degradative enzyme alpha-(N-acetylaminomethylene)succinic acid (AAMS) amidohydrolase. The recombinant enzyme expressed in Escherichia coli cells was homogeneously purified and characterized. The enzyme consisted of two subunits each with a molecular mass of 34,000+/-1,000 Da, and exhibited Km and kcat values of 53.7+/-6 microM and 307.3+/-12 min(-1), respectively. The enzyme required no cofactor or metal ion. The primary structure of AAMS amidohydrolase was elucidated for the first time here. The primary structure of the enzyme protein showed no significant identity to those of known hydrolase proteins and low homology to those of fluoroacetate dehalogenase (PDB code, 1Y37), haloalkane dehalogenase (1K5P), and aryl esterase (1VA4).     

Aspartate transcarbamylase from regenerating rat liver — A zinc-activated enzyme

The activity of aspartate transcarbamylase (EC 2.1.3.2) was significantly reduced (p<0.05) in regenerating liver from zinc-deficient rats when compared with both ad libitum and pair-fed control animals. Enzyme activity was unaffected by zinc-deficiency in non-regenerating liver. In vitro addition of zinc and a number of other divalent metal ions to enzyme extracts of regenerating liver from zinc-deficient and control rats had no significant effect on aspartate transcarbamylase activity. Dialysis of enzyme extracts against EDTA had little effect on enzyme activity. These results indicate that aspartate transcarbamylase from regenerating rat liver is a zinc-activated enzyme and that zinc associated with the enzyme is probably firmly bound.     

酶制剂厂作业环境中粉尘对工人健康的影响

目的 评价酶制剂厂作业环境中含酶粉尘和小麦粉尘对工人健康的影响.方法 对3家酶制剂厂车间空气中含酶粉尘、酶及小麦粉尘浓度和工人健康状况进行调查.用大容量采样器和个体采样器采集样品,滤膜增重法测定含酶粉尘和小麦粉尘浓度,酶活力法测定酶浓度;用问卷调查、肺功能测定、皮肤点刺试验评价工人健康效应.结果 含酶总尘、工业酶和小麦粉尘几何平均浓度分别为8.91、1.68、6.93 mg/m3.高于20mg/m3的含酶粉尘可引起眼部症状,小麦粉尘为6.93 mg/m3时可引起鼻部和皮肤症状,其中酶和小麦中的植物白蛋白可引起工人致敏效应.结论 一定浓度的含酶粉尘和小麦粉尘可对工人健康产生不良影响,有必要制定含酶总尘和小麦粉尘的职业接触限值.     

支气管肺炎患儿血清TNF-α与心肌酶水平异常改变的分析

目的观察肿瘤坏死因子-α（TNF-α）及心肌酶在小儿支气管肺炎发病中的作用。方法采用放射免疫法对60例支气管肺炎患儿（分为轻型及重型）进行了TNF-α水平检测，采用日本产olympus AU 640全自动生化分析仪检测心肌酶，并与30例正常健康儿做比较。结果小儿重型肺炎、轻型肺炎血清TNF-α水平与对照组血清TNF-α水平相比差异均有显著性（p〈0.01），小儿重型肺炎、轻型肺炎血清心肌酶水平与对照组血清心肌酶水平相比差异有显著性（p〈0.01）。结论TNF-α、心肌酶参与了小儿肺炎的发病，检测患儿血清TNF-α、心肌酶水平变化有助于支气管肺炎的诊断、判断病情和预后，并为临床治疗开辟了新的途径。