Low-Km mannose-6-phosphatase as a criterion for microsomal integrity

1998 ◽  
Vol 76 (1) ◽  
pp. 115-124 ◽  
Author(s):  
Bartholomew A Pederson ◽  
James D Foster ◽  
Robert C Nordlie
Keyword(s):  
Endoplasmic Reticulum ◽  
Structural Integrity ◽  
Kinetic Studies ◽  
Reliable Index ◽  
Single Mechanism ◽  
Induced Changes ◽  
Relationship Of ◽  
The Relationship ◽  
Low K ◽  
Hydrolysis Of

The low-Km activity of mannose-6-phosphatase (Man-6-Pase) has been used for many years to measure the structural integrity of microsomes. Recently histone II-A has been shown to activate glucose-6-phosphatase (Glc-6-Pase) and Man-6-Pase activities. However, in contrast to detergents, this compound appears to activate without disrupting microsomal vesicles (J.-F. St-Denis, B. Annabi, H. Khoury, and G. van de Werve. 1995. Biochem. J. 310: 221-224). This suggests that Man-6-Pase latency can be abolished without disrupting microsomal integrity and that even normally microsomes may manifest some low-Km Man-6-Pase activity without being "leaky." We have studied the relationship of Man-6-Pase with microsomal integrity further by measuring the latency of several enzymes reported to reside within the lumen of endoplasmic reticulum. We have also correlated this latency with the microsomal permeability of substrates for these enzymes. We found that (i) lumenal enzymes have different degrees of latency when compared with each other, (ii) permeability, as determined via osmotically induced changes in light scattering, is not always consistent with enzymatic latency, (iii) increases in the hydrolysis of Glc-6-P and Man-6-P were not parallel when microsomes were treated with low but increasing concentrations of detergent, and (iv) kinetic studies suggest that mannose-6-phosphate is hydrolyzed by untreated microsomes by more than a single mechanism. We propose that Man-6-Pase is not a reliable index of the integrity of microsomes.Key words: glucose-6-phosphatase, mannose-6-phosphatase, microsomes, rat liver, intactness.

Survey of Cyclohexylamine Content of Food Products Containing Cyclamates

1970 ◽  
Vol 53 (6) ◽  
pp. 1120-1128
Author(s):  
T Fazio ◽  
J W Howard ◽  
E O Haenni
Keyword(s):  
Weight Control ◽  
Food Product ◽  
Storage Conditions ◽  
Major Type ◽  
Processing And Storage ◽  
Relationship Of ◽  
The Relationship ◽  
And Storage ◽  
Hydrolysis Of ◽  
Content Range

Abstract A national survey was conducted to ascertain the relationship of the cyclohexylamine content of cyclamate-containing products to their composition, processing, and storage conditions. Cyclohexylamine was found in 174 of the 232 samples examined. The cyclohexylamine content range for each major type of food product was as follows: 0.0–8.2 ppm for carbonated beverages; 0.0–5.8 ppm for dry beverage bases; 0.0–1.5 ppm for fruit juices; 0.0–0.8 ppm for weight control foods; and 0.3–66 ppm for food sweetener preparations (liquid and dry base). No correlation between the cyclamate content of products and the cyclohexylamine present was evident. However, the findings indicate that significant hydrolysis of cyclamate can occur.

scholarly journals ON THE RELATIONSHIP OF LIVER GLUCOSE-6-PHOSPHATASE TO THE PROLIFERATION OF ENDOPLASMIC RETICULUM IN PHENOBARBITAL INDUCTION

1966 ◽  
Vol 31 (2) ◽  
pp. 243-256 ◽  
Author(s):  
Sten Orrenius ◽  
Jan L. E. Ericsson
Keyword(s):  
Endoplasmic Reticulum ◽  
Phosphatase Activity ◽  
Actinomycin D ◽  
Microsomal Enzymes ◽  
High Drug ◽  
Histochemical Methods ◽  
Relationship Of ◽  
The Relationship ◽  
Phenobarbital Induction ◽  
Liver Microsomal Enzymes

The differentiated effects of phenobarbital treatment on liver microsomal enzymes have been further studied. The relationship between the resulting decrease in the specific glucose-6-phosphatase activity and the enhancement of formation of endoplasmic reticulum membranes with high drug-hydroxylating activity has been investigated with biochemical and histochemical methods. Biochemically and histochemically demonstrable glucose-6-phosphatase activity was found to be present in all endoplasmic reticulum membranes, including the phenobarbital-induced smooth-surfaced proliferates, even though there was an over-all decrease in activity. Actinomycin D did not inhibit the decrease in glucose-6-phosphatase activity. The findings are discussed with reference to the enzyme-membrane relationship in phenobarbital induction.

Fatigue and Fracture Reliability and Maintainability of TLP Tendons

1993 ◽  
Vol 115 (2) ◽  
pp. 137-141 ◽  
Author(s):  
C. J. Kung ◽  
P. H. Wirsching
Keyword(s):  
System Reliability ◽  
Structural Integrity ◽  
Probability Of Detection ◽  
Structural Performance ◽  
Periodic Inspection ◽  
Maintenance Program ◽  
Fatigue And Fracture ◽  
Relationship Of ◽  
Design Factors ◽  
The Relationship

A tension leg platform (TLP) tendon system experiences oscillatory tensile stresses, and therefore is vulnerable to fatigue and fracture. Because design factors have significant uncertainty, a reliability analysis to quantify structural performance is appropriate. A maintenance program of periodic inspection and repair shows promise for improving system reliability and enhancing structural integrity. The performance of a TLP tendon system was simulated in order to study the relationship of design factors to system reliability. Effects on system reliability and maintenance performance (repair and replacement rates) can be studied as a function of (a) number of joints, J; (b) number of members, M; (c) inspection frequency; (d) inspection sensitivity as defined by the POD (probability of detection) curve; (e) ultimate strength; (f) repair policy; etc. The performance of an initially damaged or flawed tendon system is investigated. The reliability of a system that uses pressurized tendons to detect through-thickness cracks is studied, as is the vulnerability of the tendon system before replacement of broken tendons.

scholarly journals EXPERIMENTALLY INDUCED CHANGES IN NASAL MUCOUS SECRETORY SYSTEMS AND THEIR EFFECT ON VIRUS INFECTION IN CHICKENS

1969 ◽  
Vol 130 (1) ◽  
pp. 121-140 ◽  
Author(s):  
Frederik B. Bang ◽  
Marie A. Foard
Keyword(s):  
Virulent Strain ◽  
Time Intervals ◽  
Sharp Drop ◽  
Ciliary Action ◽  
Infected Cells ◽  
Unanesthetized Animals ◽  
Induced Changes ◽  
Ciliated Epithelial Cells ◽  
Relationship Of ◽  
The Relationship

Chickens 3 wk old, inoculated intranasally with a mesogenic (moderately virulent) strain of Newcastle disease virus, developed necrotic lesions of the mucous acini, predominantly of the middle turbinates. The infection subsequently spread to involve much of the rest of the mucosa, including mucous and ciliated epithelial cells, and other acini. The early phase of adsorption of a virulent strain of the virus to the middle turbinates of chicks 5–21 days of age was studied by giving a standard inoculum intranasally to unanesthetized animals. Variation in amounts adsorbed by individual chickens was large, but was minimized by making measurements on pools of turbinates from three chicks at intervals of 1, 3, and 5 hr after exposure of the excised turbinates to antibody, by washing, and by trypsinization. The virus released from the cells into the trypsin was designated as adherent virus, and the infectious virus in the cells after destruction of the cells by water grinding, as cell virus. Paralysis of ciliary action by cocaine increased the number of infected cells in the turbinates about 10-fold at all three time intervals. Pilocarpine injection before virus inoculation caused a large increase in the amount of infected cells 1 hr after virus administration, but was followed by a sharp drop in infected cells by 3 or 5 hr. Pilocarpine given after the virus decreased the number of infected cells and changed the relationship of infected cells to adherent virus. Exposure of chicks to sustained or severe cold caused a similar but less marked effect. The drop in infected cells was restored to control values if chicks were returned to brooder temperatures. The marked drop of infected cells produced by pilocarpine and cold in living chicks, and in cultures of chicken trachea (previous study), is consonant with the idea that virus has been adsorbed on mucus granules in the mucous cells of the turbinates and then has been reexcreted, as unincorporated virus, into the moving mucous sheet. A series of accessory data support this interpretation.

scholarly journals Adaptive increase in phytate digestibility by phosphorus-deprived rats and the relationship of intestinal phytase (EC 3.1.3.8) and alkaline phosphatase (EC 3.1.3.1) to phytate utilization

1983 ◽  
Vol 49 (1) ◽  
pp. 145-152 ◽  
Author(s):  
Robert J. Moore ◽  
Trygve L. Veum
Keyword(s):  
Alkaline Phosphatase ◽  
Inositol Phosphates ◽  
Enzymic Hydrolysis ◽  
Intestinal Alkaline Phosphatase ◽  
Alkaline Phytase ◽  
Treatment Groups ◽  
Phosphorus Deprivation ◽  
Relationship Of ◽  
The Relationship ◽  
Hydrolysis Of

1. The effects of phosphorus deprivation on phytate digestibility, phosphorus utilization and intestinal phytase (EC3.1.3.8) and alkaline phosphatase (EC3.1.3.1) in rats were investigated.2. P deprivation was achieved by giving rats a diet containing 3 g P/kg and resulted in hypophosphataemia, hypercalcaemia, hypercalciuria, and lower levels of P absorbed and retained, and calcium retained.3. Rats adapted to P deprivation by increasing the digestion of total dietary-P and phytate-P.4. Levels of intestinal alkaline phosphatase and alkaline phytase were not different between the two treatment groups.5. P deprivation in the rats given the marginal-P diet may be a result of a lower absorption of total dietary-P or increased absorption of inositol phosphates formed during the enzymic hydrolysis of phytate which are not readily utilized by the rat.6. These results suggest that intestinal phytase and alkaline phosphatase do not play a role in the adaptive increase in phytate digestibility by rats given marginal-P diets. The adaptation may result from enhanced phytase or alkaline phosphatase synthesis by the gastrointestinal microflora stimulated by a lower level of P in the digesta.

scholarly journals Regulation of pyruvate dehydrogenase activity in rat epididymal fat-pads and isolated adipocytes by adrenaline

1978 ◽  
Vol 174 (1) ◽  
pp. 119-130 ◽  
Author(s):  
S J Smith ◽  
E D Saggerson
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Acid Synthesis ◽  
Maximum Decrease ◽  
Isolated Adipocytes ◽  
Induced Changes ◽  
Relationship Of ◽  
The Relationship ◽  
Dose Dependent ◽  
Fat Pads

1. Dose-dependent effects of adrenaline on PDHa activity were investigated with both incubated rat epidiymal fat-pads and isolated adipocytes. 2. Adrenaline (10nM- 5 micrometer) decreased PDHa activity in fat-pads incubated with 5 mM-[U-14C]glucose + insulin (20 munits/ml). Changes in [U-14C]glucose incorporation into fatty acids in these tissues correlated only loosely with changes in PDHa activity. There was a good inverse relationship between adrenaline-induced changes in PDHa activity and increases in lipolysis (glycerol release). 3. Adrenaline (10nM - 0.5 micrometer) decreased PDHa activity in fat-pads incubated with 5 mM-[U-14C]pyruvate + insulin (20 munits/ml), whereas 1 micrometer- and 5 micrometer-adrenaline slightly increased PDHa activity. All concentrations of adrenaline tested decreased [U-14C]pyruvate incorporation into fatty acids. Between 10nM- and 0.5 micrometer-adrenaline percentage decreases in PDHa activity paralleled decreases in faty acid synthesis. 4. Effects of adrenaline on PDHa activity and fatty acid synthesis in fat-pads incubated with 5mM-[U-14C]pyruvate + insulin (20 munits/ml) could not be mimicked by addition of albumin-bound palmitate. 5. The response of PDHa activity to adrenaline (0.1 nM - 1 micrometer) in isolated adipocytes differed with the carbohydrate substrate used in the incubations. With 5 mM-glucose + insulin (20 munits/ml), PDHa activity was significantly increased by 10 nM-adrenaline, but not by 1 micrometer-adrenaline, the response to adrenaline being biphasic. There was some correlation between PDHa activity and accumulation of non-esterified fatty acids. With 5 mM-glucose alone adrenaline (0.1 nM - 1 micrometer) had no effect on PDHa activity even though lipolysis was increased by adrenaline (0.1 micrometer - 1 micrometer). With 5mM-fructose in the presence and absence of insulin, lipolytic doses of adrenaline decreased PDHa activity. No tested concentrations of adrenaline increased PDHa with this substrate. 6. In the presence of 5 mM-fructose, palmitate was significantly more effective than adrenaline with respect to the maximum decrease in PDHa activity that could be elicited. 4. The relationship of changes in PDHa activity to changes in lipogenesis and the likelihood of adrenaline-induced changes in PDHa activity being secondary to changes in non-esterified fatty acid metabolism are discussed.

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