Changes in Ca, Mg-dependent endonuclease of DNA in isolated nuclei of human lymphocytes in lymphoproliferative diseases

Ca, Mg-dependent endonuclease is one of the main DNAses of lymphocyte chromatin. It's activity is known to increase in the immune response and to decrease in spontaneous and experimental CLL. These observations became a basis for analysis of possible clinical meaning of it's enzymatic activity assay. Donors' peripheral blood lymphocytes being tested, normal level of endonucleolysis for men and children was defined. Except that patients with different clinical forms of lymphoproliferative diseases such as chronic lympholeukemia, non-Hodgkin lymphomas, Hodgkin's disease were observed. The results showed that Ca, Mg-dependent endonucleolysis activity was decreased in comparison to donors' one. Ca, Mg-dependent endonucleolysis activity was the same in the group of patients with non-malignant pathology and in donors' one. Successful treatment and remission state of our patients was associated with alteration of the Ca, Mg-dependent endonucleolysis activity to normal level as well as immunological parameters. That is why the activity of Ca, Mg-dependent endonucleolysis is suggested to be a new criterion of immune state and lymphocyte malignant transformation.     

Studies on Cytochemistry of Albuminous Ceils in Secondary Phloem of Stem in Pinus bungeana Zucc.

Mature albuminous cells which are connected with differentiated and functional sieve cells show rather high activity of acid phosphatase at pH 5.0. No increased activity could be detected in ordinary ray cells, cambium cells and young albuminous cells contiguous with developing sieve cells. Collapsed albuminous cells show little or none of the activity. With ATP as substrate, enzyme localization is the same as with β-glycerolphosphate. When adenosine triphosphatase activity is visualized at pH 7.2 with ATP as substrate, the highest activity still localized in mature albuminous cells. With the development of young albuminous cells, the enzyme activity is being gradually exhibited, but disappearing when the maturecells begin collapsing. On the other hand, in ordinary ray cells the enzyme activity is ahnost not detectable.     

Clearing-factor lipase in adipose tissue. Distinction of different states of the enzyme and the possible role of the fat cell in the maintenance of tissue activity

1. Incubation of intact epididymal adipose tissue from fed rats at 37 degrees in an albumin solution at pH7.4 in vitro results in rapid loss of clearing-factor lipase activity until a low activity, stable to prolonged incubation, is attained. The clearing-factor lipase activity of intact tissue from starved rats, which is initially much less than that of tissue from fed rats, is mainly stable to incubation at 37 degrees . 2. Much of the clearing-factor lipase activity of intact epididymal adipose tissue from fed rats is inactivated by collagenase. The enzyme activity of intact tissue from starved rats is not inactivated by collagenase. 3. The clearing-factor lipase activity of fat cells isolated from the epididymal adipose tissue of fed rats is stable to prolonged incubation at 37 degrees . It represents only a small proportion of the total activity of the intact tissue. In starved rats, the isolated fat cells contain a much higher proportion of the activity of the intact tissue. Their activity is also stable at 37 degrees . 4. Incubation of isolated fat cells in a serum-based medium leads to a progressive rise in clearing-factor lipase activity. Actinomycin increases the extent of this rise in activity. No rise in clearing-factor lipase activity occurs when stromal-vascular cells isolated from epididymal adipose tissue are incubated in the medium. 5. The findings indicate that less than 20% of the activity of intact adipose tissue from fed rats is retained when fat cells are isolated from the tissue by collagenase treatment. The activity that is lost could be that which normally functions in the uptake of triglyceride fatty acids by the tissue.     

A comparative evaluation of the level of sphingomyelinase activity in liver cell nuclei and in the brain

It was discovered that there is sphingomyelinase activity in the rat liver nuclei. The maximum of enzyme activity is at pH 7.1. The data obtained demonstrated that the main part of sphingomyelinase is located in the nuclear membrane. Comparison of sphingomyelinase activity in cell nuclei, liver and brain homogenates shows high level of enzyme activity in the nuclei. The authors discuss possible participation of sphingomyelinases in changes of phospholipids composition in nuclear structure under different functional activity of cell nuclei.     

Role of extralaryngeal muscles in phonation of subhuman primates

1. The electromyographic activity of eight external laryngeal and hyoid muscles was recorded during vocalization in the squirrel monkey (Saimiri sciureus). Calls of different types were elicited by electrical stimulation of the central grey of the midbrain in narcotized animals.
2. Peeping, a short, high-pitched call with minor frequency modulations, is associated with a marked activity in the cricothyroid, a moderate activity in the thyrohyoid, a weak activity in the sternohyoid and no activity in the sternothyroid, omohyoid, mylohyoid and anterior digastric muscles.
3. Chuck, a short, plosive call with a steep frequency descent over several kHz, is associated with a marked activity in the cricothyroid, a moderate activity in the thyrohyoid, sternothyroid and mylohyoid, a weak activity in the sternohyoid and omohyoid, and no or rare activity in the anterior digastric and inferior pharyngeal constrictor, respectively.
4. Cackling, a long and loud call consisting of alternating high- and low-pitched elements which follow each other repetitively in a 12–14 Hz rhythm, is associated with a similar muscular activity pattern as chuck except that the sternohyoid activity is relatively stronger.
5. Cawing, a short low-pitched call with a fundamental frequency of 200–700 Hz, shows a moderate activity in the sternothyroid, an occasional activity in the thyrohyoid and no activity in the cricothyroid, sternohyoid, omohyoid, anterior digastric and inferior pharyngeal constrictor.

     

Changes in the Na, K-ATPase of neuronal membranes in penicillin-induced epileptic foci in the cerebral cortex of the rat]

The relationship between electrophysiological changes and Na, K-ATPase activity of neuronal membranes in sodium penicillin-induced epileptic foci was studied. Na,K-ATPase activity is inhibited both in the primary focus and in homotopic contralateral area during latent period and in the stage of forming epileptic activity. In the stage of marked convulsive activity Na, K-ATPase is inhibited only in the primary focus. It is shown that penicillin at a concentration range of 2 x 10(-6)--2 x 10(-3) M does not influence Na,K-ATPase activity of crude synaptosomes of the rat brain cortex. It is suggested that Na,K-ATPase inactivation may serve as a pathogenetic factor in the development of convulsive process.     

Role of water activity in ethanol fermentations

A separate role for water activity in the conversion of sugars to ethanol by two strains of yeast is identified. During fermentation of both single and mixed sugar substrates, the water activity was shown to remain constant during the logarithmic growth phase. This is despite the changes in concentration of substrates and product, the constancy reflecting the fact that the greater influence of ethanol on the solution activity is counterbalanced, in the early stages of the fermentation, by its low yield. The end of the log phase of growth coincides with the start of a period of gradually decreasing water activity. For the more ethanol-tolerant strain UQM66Y, growth was found to cease at a constant value of water activity while that for the less tolerant strain UQM70Y depended on both ethanol concentration and water activity. It is argued that water activity is a more appropriate variable than ethanol concentration for describing some of the nonspecific inhibitory effects apparent in ethanol fermentations. A straightforward method for the calculation of water activity during such fermentations based on the use of solution osmolality is presented.     

Change in the adenylate cyclase activity of the lymphocytes and thrombocytes in irradiated sheep

Changes in basal and prostaglandin stimulated activity of adenylate cyclase in lymphocytes and platelets of irradiated sheep are phasic. In platelets adenylate cyclase activity is maximum on days 5 and 10 following irradiation, whereas in lymphocytes the enzyme activity is maximum on day 7. cAMP phosphodiesterase activity is slightly changed in platelets and increased in lymphocytes of exposed sheep.     

Involvement of diminution of glutathione, produced by deficiency of methionine in the diet, in the elevation of malic enzyme level in rat liver

Rats fed on a low protein diet show an increase in the specific activity of malic enzyme and a concomitant decrease of glutathione concentration. We have studied the effect on malic enzyme activity of supplementing of low protein diet with essential amino acids. Only when methionine was excluded from the diet did the specific activity of malic enzyme increase to the same extent as found in rats fed with low protein diet. Immunoprecipitation of malic enzyme indicated that specific activity changes are the result of changes in the amounts of enzyme. Under all dietary conditions studied, the increase in malic enzyme activity is associated with a decrease in the concentration of GSH. To evaluate the possible causative role of GSH in malic enzyme induction, the specific activity of malic enzyme was measured in rats treated with BSO, an inhibitor of GSH biosynthesis. The results show that in BSO-treated rats the decrease of GSH levels is also accompanied by an increase in the activity of malic enzyme.     

Involvement of Calcium in the Regulation of Serotonin N-Acetyltransferase in Retina

The possible involvement of calcium in the regulation of retinal serotonin N-acetyltransferase (NAT) activity was investigated using eye cups of Xenopus laevis cultured in defined medium. Omitting CaCl2 from the culture medium completely inhibited the dark-dependent increase of NAT activity at night. Approximately 10(-4)-10(-3) M free Ca2+ was found to be required for the maximal increase of NAT activity in the dark. Other divalent cations--Ba2+, Sr2+, and Mn2+--did not substitute for Ca2+. Antagonists of voltage-sensitive calcium channels, including nifedipine, methoxyverapamil (D600), Co2+, and Mg2+, were found to be effective inhibitors of the dark-dependent increase of retinal NAT activity. Trifluoperazine also decreased retinal NAT activity. These studies indicate that the increase of retinal NAT activity in the dark is mediated by a specific Ca2+-dependent process and that Ca2+ influx through voltage-sensitive calcium channels is involved.     

Functional analysis of the hemK gene product involvement in protoporphyrinogen oxidase activity in yeast

The Escherichia coli hemK gene has been described as being involved in protoporphyrinogen oxidase activity; however, there is no biochemical evidence for this. In the context of characterizing the mechanisms of protoporphyrinogen oxidation in the yeast Saccharomyces cerevisiae, we investigated the yeast homolog of HemK, which is encoded by the ORF YNL063w, to find out whether it has any protoporphyrinogen oxidase activity and/or whether it modulates protoporphyrinogen oxidase activity. Phenotype analysis and enzyme activity measurements indicated that the yeast HemK homolog is not involved in protoporphyrinogen oxidase activity. Complementation assays in which the yeast HemK homolog is overproduced do not restore wild-type phenotypes in a yeast strain with deficient protoporphyrinogen oxidase activity. Protein sequence analysis of HemK-related proteins revealed consensus motif for S-adenosyl-methionine-dependent methyltransferase.     

Subcellular localization of superoxide dismutase in rat liver.

The subcellular localization of superoxide dismutase was investigated in rat liver homogenates. Most of the superoxide dismutase activity is present in the soluble fraction (84%), the rest being associated with mitochondria. No indications for the occurrence of superoxide dismutase in other subcellular structures, particularly in peroxisomes, was found. Mitochondrial activity is not due to adsorption, since the sedimentable activity is essentially latent. Subfractionation of mitochondria by hypo-osmotic shock and sonication shows that half of the mitochondrial superoxide dismutase activity is localized in the intermembrane space, the rest of the enzyme being a component of the matrix space. In non-ionic media the matrix enzyme is, however, adsorbed to the inner membrane, from which it can be desorbed by low (0.04M) concentration of KCl. Superoxide dismutase activity was found in all rat organs investigated. Maximal activity of the enzyme is observed in liver, adrenals and kidney. In adrenals, the highest specific activity is associated with the medulla.     

Changes in subcellular distribution of S-adenosylmethionine decarboxylase in regenerating and in developing rat liver

Distribution of the activity of S-adenosylmethionine decarboxylase in homogenates of rat liver generating after partial hepatectomy and during development are reported. In the stages of rapid growth of liver remaining after partial hepatectomy, and increased activity of S-adenosylmethionine decarboxylase in the supernatant fractions is accompanied by a decreased activity in the crude nuclear fractions. Prior to birth, in the liver of the developing rat, all activity of S-adenosylmethionine decarboxylase is in the supernatant fraction. After birth, activity in the crude nuclear fraction increases rapidly, reaching adult values by the end of weaning.     

Properties of diacylglycerol kinase in adult and fetal rat lung

Diacylglycerol kinase activity is found in both adult and fetal lung. Approximately 27 and 52% of the total activity is found in microsomes and cytosol, respectively. The activity is maximal at pH 7.4. The apparent Km for ATP is 0.11 mM and 0.21 mM for cytosol and microsomes, respectively. The apparent Km for dioleoylglycerol is 0.05 mM for cytosol and 0.14 for microsomes. Maximal activity in cytosol and microsomes is obtained with 2.0 mM dexoycholate. Other detergents cannot substitute for deoxycholate. Phosphatidylglycerol stimulates activity in the absence and in the presence of deoxycholate. Phosphatidylserine also stimulates activity, whereas phosphatidylethanolamine was inactive and phosphatidylcholine inhibited the reaction. Linoleic acid produced inhibition. The general properties of the enzyme were similar for fetal and adult lung. Diacylglycerol kinase from microsomes and cytosol fraction from both fetal and adult lung was most active with dioleoylglycerol and diacylglycerol from egg phosphatidylcholine. Significantly lower activity was obtained with dipalmitoylglycerol. Phosphatidylglycerol did not alter the relative substrate preferences. The activity in microsomes increased with development from 19 days gestation to a maximal activity at 21 days gestation. Maximal activity was about 2-fold higher than the adult. The activity dropped rapidly reaching adult values prior to birth (22 days gestation). The activity in cytosol fractions increased gradually from 19 days gestation, reaching adult values by 22 days gestation.     

Calcium-Dependent Transglutaminase of Rat Sympathetic Ganglion in Development and After Nerve Injury

The activity of transglutaminase (TG) was examined in the rat superior cervical ganglion (SCG) during development and after postganglionic nerve crush. During postnatal development the enzyme activity is increased by sevenfold in parallel to protein content of the ganglion and reaches adult levels by day 35 after birth. The endogenous activity (enzyme activity assayed in the absence of the exogenous substrate) during development is transiently elevated with a peak at day 21 postnatal. In the adult ganglion the enzyme specific activity is evenly distributed in all subcellular compartments, but most of it is contained in the cytosol. Within the first hour after axotomy TG activity is rapidly and transiently elevated. The peak value, 80% above control levels, is attained by 30 min postoperative. At this time the activity is increased in all subcellular fractions, but the endogenous activity is selectively increased in the fraction containing nuclei. The enhanced TG activity after axotomy can be prevented by topical treatments with verapamil, an inhibitor of voltage-dependent calcium fluxes across excitable membranes, or with the calcium chelator EGTA. The results show that intracellular TG activity is present in the SCG and that it increases with postnatal growth of the ganglion. After axotomy the enzyme activity is rapidly and transiently increased in the ganglion and this elevation critically depends on calcium fluxes.     

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.     

Role of physical activity in preventing and treating obesity.

There is an inverse relationship between physical activity and weight gain. However, additional research is needed to quantify the amount of physical activity required to prevent weight gain in different populations, improve the way we convey physical activity recommendations to the public, and help the individuals increase their physical activity. Although physical activity does not appear to contribute significantly to weight loss, it is critical for maintenance of weight loss. Available data are consistent in that 60-90 min/day of moderate-intensity physical activity is required to maintain a significant weight loss. Although there is agreement about the need for high levels of physical activity to maintain weight loss, there is a need for more research to understand why physical activity is critical for weight loss maintenance. Finally, additional research is needed to determine whether there is an optimal level of physical activity below which it is difficult for most people to achieve a balance between energy intake and expenditure at a healthy body weight. The increasing prevalence of obesity may reflect the fact that the majority of the population has fallen below such a level of physical activity.     

Regulation of hydrogenase activity in enterobacteria.

Proteus vulgaris, Escherichia coli, and Citrobacter freundii cells were devoid of hydrogenase activity when grown on complex medium or minimal medium plus glucose in the presence of saturating levels of dissolved oxygen. Anaerobically grown cells had appreciable hydrogenase activity. Cells grown anaerobically in the presence of CO (an inhibitor of hydrogenase) or nitrate (an electron acceptor) lacked hydrogenase activity. To make hydrogenase essential for anaerobic growth, cells were grown on fumarate, a nonfermentable carbon source. P. vulgaris and C. freundii evolved H2 gas under these conditions, and the hydrogenase-specific activity was 8 to 10 times greater than that in cells grown on glucose. Cell growth was inhibited by CO, and the cells grew but lacked hydrogenase activity when grown in the presence of nitrate. E. coli grew on fumarate plus H2, and the specific activity was five times greater than that in cells grown on glucose. Thus, hydrogenase activity is inducible and is expressed maximally when the enzyme is essential for cellular growth. Under conditions of growth where the enzyme would not be catalytically active, cells contain little active hydrogenase. Under anaerobic conditions where the enzyme is not essential for growth, the level of hydrogenase activity is intermediate.     

Regulation of amylase activity in Drosophila melanogaster: Effects of dietary carbohydrate

The level of amylase activity in larvae and adults of Drosophila melanogaster is dependent on the dietary carbohydrate source; flies or larvae from a food medium containing starch show higher levels of activity than individuals from a food containing simple sugars. This is shown to be due to repression of activity by sugars rather than enhancement of activity by starch. Moreover, the changes in enzyme activity reflect a change in enzyme quantity rather than a change in catalytic efficiency. The seeming stimulation of amylase activity by sucrose in some experiments is due, simply, to comparisons with "starvation" diets which cause a large nonspecific reduction in enzyme activity. Though all strains tested showed repression of enzyme activity by simple sugars, the degree of repression varies between strains. Also, in those strains which carry a duplication of the amylase structural gene, the two isozymal forms of amylase can be differentially repressed by dietary sugars.     

Development of phosphodiesterase activity in the chick retina

Significant cyclic GMP phosphodiesterase activity is apparent in the early stages of development of the chick neural retina. By day 8, specific activity drops by approximately two-thirds. After day 14, a sharp rise in activity is observed, continuing through the time of hatching. Cyclic AMP phosphodiesterase activity is considerably lower and does not markedly change over the embryonic period.