Peroxidase and amylase isoenzymes in the sapwood and heartwood of trees

Peroxidases and amylases have been found in the sapwood and the heartwood of both angiosperm and gymnosperm trees. Cambial and outer layers of xylem of     

Effect of experimental diabetes on the activity of hexokinase isoenzymes in tissues of the rat

The effect of experimental diabetes on the activity of hexokinase isoenzymes was studied in a wide range of tissues of the rat. In the tissues known to require insulin for glucose phosphorylation, the activity of hexokinase was markedly decreased; the fall being mainly in the Type IV (Glucokinase) in liver and Type II in other tissues, these tissues also exhibit glucose underutilization in diabetes. In the tissues which are commonly known not to require insulin, the activity of Type I hexokinase was significantly increased, these tissues exhibit aspects of glucose overutilization in diabetes in particular kidney and lens. These changes are discussed in relation to Spiro's hypothesis of glucose under and overutilization in tissues in diabetes.     

Changes in serum amylase and its isoenzymes after whole body irradiation.

A study was carried out to assess the effect of total body irradiation on pancreatic and parotid isoenzymes of amylase in patients about to undergo bone-marrow transplantation who had received high-dose cyclophosphamide. Twelve patients were studied, enzyme activity being measured before and at various times after total body irradiation. Serum total amylase activity rose rapidly within 12 hours of irradiation to a maximum at 36 hours, returning to normal by six days; most of the increase was derived from salivary damage, with a much smaller pancreatic component. These results confirm that radiation produces acute changes in amylase activity, which may be of use in assessing radiation-induced damage.     

Hexokinase isoenzymes in tissues of the adult and developing guinea pig

Changes in the activities and isoenzyme distribution of hexokinase were determined in a number of tissues during the development of the guinea pig. The total activity in the fetal liver showed a large fall during the second half of gestation to reach adult values by term. With normal diet the fetal, neonatal, and adult livers had isoenzymes I and III but little or no detectable IV (glucokinase). The fetal liver had predominantly type I, but the proportion of type III increased during development. The kinetics of the guinea pig isoenzymes were similar to those reported for the rat. Two additional isoenzymes with mobility between I and II were detected in the fetal liver and blood. They appear to have kinetic properties similar to type I. Detectable liver glucokinase activity was induced by glucose administration to adult guinea pigs. The total activity in kidney, brain and skeletal muscle showed a postnatal rise while in the fetal heart it was high and declined after birth. These tissues contained predominantly type I with varying proportions of type III hexokinase. The ratio of particulate-bound to soluble hexokinase varied from tissue to tissue. All except the liver showed a significant increase in binding after birth. The changes are discussed in relation to the control of glucose utilization in the fetal and neonatal periods.     

Analysis of the phosphofructokinase subunits and isoenzymes in human tissues.

The 6-phosphofructo-1-kinase (PFK) subunits and isoenzymes were studied in human muscle, heart, brain, liver, platelets, fibroblasts, erythrocytes, placenta and umbilical cord. In each tissue, the subunit types in the native isoenzymes were characterized by immunological titration with subunit-specific antibodies and by column chromatography on QAE (quaternary aminoethyl)-Sephadex. Further, the subunits of the partially purified native isoenzymes were resolved by SDS/polyacrylamide-gel electrophoresis, identified by immunoblotting, and quantified by scanning gel densitometry of silver-stained gels and immunoblots. Depending on the type of tissue, one to three subunits were detected. The Mr values of the L, M and C subunits regardless of tissue were 76,700 +/- 1400, 82,500 +/- 1640 and 86,500 +/- 1620. Of the tissues studied, only the muscle PFK isoenzymes exhibited one subunit, which was the M-type subunit. Of the other tissues studied, the PFK isoenzymes contained various amounts of all three subunits. Considering the properties of the native PFK isoenzymes, it is clear that, in human tissues, they are not simply various combinations of two or three homotetrameric isoenzymes, but complex mixtures of homotetramers and heterotetramers. The kinetic/regulatory properties of the various isoenzyme pools were found to be dependent on subunit composition.     

Fasting-induced changes of tyrosine transaminase activity in rat tissues

Tyrosine transaminase activity in liver, kidney, intestine, stomach, skin, adipose tissue, striated muscle and brain in fed and 24-hour fasted rats, has been studied. Maximal activity has been found in liver, with only fractional activity in the other tissues. 24 hour fasting induced significant decrease in liver and adipose tissue activity, while no changes have been detected in the other tissues. The possible implications of these facts are discussed.     

Lactate dehydrogenase isoenzymes in benign and malignant prostatic tissues

84 prostatic tissue specimens consisted of 62 benign hyperplasias and 22 carcinomas have been studied regarding Lactate dehydrogenase isoenzymes pattern. A consistent and definite shift of the LDH5 : LDH1 ratio has been found in carcinomas respect to benign hyperplasias.     

小鼠组织中过氧化氢酶的活性与年龄的关系

为观察小鼠组织中过氧化氢酶的活性与年龄的关系,采用高锰酸钾滴定法测定不同年龄(1、4、18月龄)小鼠肝、肾、肺、心、脾、胃、脑组织中过氧化氢酶的活性。结果显示:小鼠过氧化氢酶在不同组织中活性不同,活性高低顺序基本表现为:肝>肾>肺>心、脾、胃>脑;小鼠肺、心、脾、胃、脑各组织中过氧化氢酶的活性在1～4月龄间随年龄增加而增加,在4～18月龄间随年龄增加而降低;小鼠肝、肾组织中过氧化氢酶的活性在1～4月龄间与年龄相关性不显著,在4～18月龄间随年龄增加而降低。结果表明,小鼠肝、肾、肺、心、脾、胃、脑等组织中过氧化氢酶的活性随年龄变化而变化,机体过氧化氢酶活性的降低与机体衰老密切相关。