Parenteral soya bean fat emulsions potentiate the hepatotoxicity of E. coli endotoxin in suckling rats

A dose of soy bean fat emulsion which was injected i.v. in suckling rats accumulated in the cells of liver parenchyma, both in hepatocytes and in reticuloendothelial cells. Subsequent i.p. injection of E. coli endotoxin was followed by extensive liver tissue necrosis and increased activities of serum aspartic and alanine aminotransferase. These signs of liver damage were markedly more pronounced than those observed after the administration of E. coli endotoxin only.     

Hypersensitivity to endotoxin hepatotoxicity in rats with inflammatory lesions

Summary The ratio of sinusoidal nonparenchymal cells to hepatocytes in rat liver was significantly increased following induction of inflammation, and decreased after subsequent exposure to endotoxin, particularly in the region around the terminal portal venules. Rats with inflammatory lesions were more sensitive to endotoxin hepatocytotoxicity than normal controls, as judged from the dose-dependent increase in activity of serum transaminases and from the extent of liver tissue injury. In addition, these animals, which were already in a state of depletion of hepatic glycogen, demonstrated marked hyperglycemia 24 h after endotoxin administration in small doses of less than 2 mg/kg.     

Hypersensitivity to endotoxin hepatotoxicity in rats with inflammatory lesions

The ratio of sinusoidal nonparenchymal cells to hepatocytes in rat liver was significantly increased following induction of inflammation, and decreased after subsequent exposure to endotoxin, particularly in the region around the terminal portal venules. Rats with inflammatory lesions were more sensitive to endotoxin hepatocytotoxicity than normal controls, as judged from the dose-dependent increase in activity of serum transaminases and from the extent of liver tissue injury. In addition, these animals, which were already in a state of depletion of hepatic glycogen, demonstrated marked hyperglycemia 24 h after endotoxin administration in small doses of less than 2 mg/kg.     

Dietary vitamin E does not protect from endotoxin-induced hepatic microvascular dysfunction

Starting from the concept that lipopolysaccharide (LPS)-associated hepatotoxicity involves the action of reactive oxygen species, the present study was conducted to test whether vitamin E, a lipophilic antioxidant, prevents LPS-induced hepatic microvascular dysfunction and liver injury. Fifty-two rats were divided into three groups and fed diets containing 0 (n=16), 75 (n=18) or 8000 mg (n=18) α-tocopherol acetate/kg food for four weeks. At 1 h and 6 h after intravenous LPS-exposure (10 mg/kg E. coli LPS) hepatic microvascular response and liver injury were assessed by the analysis of Kupffer cell phagocytic activity, leukocyte-endothelial cell interaction and nutritive sinusoidal perfusion (intravital fluorescence epi- illumination technique) as well as bile flow, serum liver enzyme activities and tissue histomorphology. In animals fed with 75 mg vitamin E/kg (standard diet), LPS caused hepatic Kupffer cell activation (increased phagocytic activity) and hepatic microvascular leukocyte activation, with stasis in sinusoids and adherence in postsinusoidal venules (1 h) followed by leukocytic infiltration into tissue (6 h) and progredient sinusoidal perfusion failure (6 h). Hepatic microvascular injury was accompanied by reduced bile flow and enhanced liver enzyme release. Vitamin E-enriched diet (8000 mg/kg) and even vitamin E-deficient diet did not significantly affect LPS-induced hepatic microvascular cell activation and perfusion failure. Thus, we conclude, that vitamin E is not effective to protect from endotoxin-induced hepatic microvascular dysfunction. Received 7 November 1996; received after revision 30 December 1996; accepted 20 January 1997     

Suppression of pupal esterase activity in Aedes aegypti (Diptera: Culicidae) by an insect growth regulator.

Changes in non-specific esterases of Aedes aegypti were noted during pupal development. One esterase band was found to increase markedly within 3 h of pupation and this increase in activity was suppressed by prior treatment of larvae with an insect growth regulator, ZR 515. It is suggested that the esterase activity may help to reduce endogenous levels of juvenile hormone during metamorphosis and that the growth regulator may prevent this normal regulation.     

Parenteral soya bean fat emulsions potentiate the hepatotoxicity ofE. coli endotoxin in suckling rats

Summary A dose of soy bean fat emulsion which was injected i.v. in suckling rats accumulated in the cells of liver parenchyma, both in hepatocytes and in reticuloendothelial cells. Subsequent i.p. injection ofE. coli endotoxin was followed by extensive liver tissue necrosis and increased activities of serum aspartic and alanine aminotransferase. These signs of liver damage were markedly more pronounced than those observed after the administration ofE. coli endotoxin only.     

Increased pheromone catabolism by antennal esterases after adult eclosion of the cabbage looper moth

Summary A marked increase in pheromone hydrolysis by antennal esterases occurred 24–72 h after eclosion and was coincident with the age ofTrichoplusia ni (Hübner) males that were maximally responsive to the pheromone as indicated from previous reports. This observed hydrolytic activity was also accompanied by the appearance of 3 esterase bands in the electrophoretic patterns of the antenna. The finding thus lends support to the hypothesis that the observed pheromone catabolism is an event closely associated with the olfaction process.Employed through a cooperative agreement with the Insect Attractants, Behavior, and Basic Biology Research Laboratory, Agricultural Research, Science and Education Administration, USDA, Gainesville, FL 32604.The authors acknowledge Dr James L. Nation for his helpful comments during the course of the work.     

Monolayer culture of adult mouse hepatic cells secreting albumin and alpha fetoprotein]

Adult mouse liver cells obtained by enzymatic dispersion were maintained in primary cultures for up to 4 weeks. They retained some of the typical morphological and ultrastructural characteristics of hepatocytes. After 2 days of culture, structures similar to bile canaliculi were found and after 6 days clusters of small proliferating cells were noticed in the gaps of the monolayer formed by large well-spread hepatocytes. Almost all 3-day cultures began to secrete alphafetoprotein for about 2 weeks, whereas albumin was secreted throughout the period of culture.     

2 new esterase loci Es-14 and Es-15 in mice (genus Muc L.) : characterization by different substrates and inhibitors]

Allelic differences at an esterase locus designated Es-14 exist between Mus musculus (both inbred strains and wild Mice) and Mus spretus. This locus is expressed in a variety of tissues. Mus musculus has been assigned the allele Es-14r while Mus spretus carries the alternate alleles Es-14l. Each phenotype manifests itself as a single band of enzyme activity and F1 hybrids show two bands corresponding to the parental forms. Allozyme variation was also detected at another esterase locus, temporarily disignated as Es-15 until confirmed by current linkage analysis. A slow variant Es-15 was recorded in a Mus musculus population from Greece while inbred strains carry the Es-15m allele. Study of a Mus spicilegus population from Greece revealed the presence of a third allele, Es-15r. Substrate and inhibition characteristics are provided for both loci.     

Development and hormonal control of thioredoxin and the thioredoxin-reductase system in the rat liver during the perinatal period

The development and hormonal regulation of thioredoxin and of the thioredoxin-reductase system were investigated during the perinatal period in rat liver. An immunological procedure was developed in order to quantify thioredoxin in fetal and neonatal hepatocytes. Both immunoreactive thioredoxin and thioredoxin-reductase activity appeared on day 16.5 of pregnancy. The level of immunoreactive thioredoxin increased during the late fetal period, and its level was the same 24 h after birth. Moreover, its development was not subjected to hormonal regulation by corticosteroids and glucagon. In contrast, thioredoxin-reductase activity increased 3 times during the late fetal period and presented a marked increase 24 h after birth. In the absence of glucocorticoids there was no increase in the level of thioredoxin reductase, while administration of hydrocortisone acetate and glucagon to fetuses prematurely evoked its activity. This study suggests that if thioredoxin acts physiologically, this activity is related to the state of reduction of the molecule rather than to the total concentration in the liver.     

Development and hormonal control of thioredoxin and the thioredoxin-reductase system in the rat liver during the perinatal period

Summary The development and hormonal regulation of thioredoxin and of the thioredoxin-reductase system were investigated during the perinatal period in rat liver. An immunological procedure was developed in order to quantify thioredoxin in fetal and neonatal hepatocytes. Both immunoreactive thioredoxin and thioredoxin-reductase activity appeared on day 16.5 of pregnancy. The level of immunoreactive thioredoxin increased during the late fetal period, and its level was the same 24 h after birth. Moreover, its development was not subjected to hormonal regulation by corticosteroids and glucagon. In contrast, thioredoxin-reductase activity increased 3 times during the late fetal period and presented a marked increase 24 h after birth. In the absence of glucocorticoids there was no increase in the level of thioredoxin reductase, while administration of hydrocortisone acetate and glucagon to fetuses prematurely evoked its activity. This study suggests that if thioredoxin acts physiologically, this activity is related to the state of reduction of the molecule rather than to the total concentration in the liver.     

The effect of physostigmine on (Na+ + K+)-ATPase activity in different rat brain regions

The activity of (Na+ + K+)-ATPase and acetylcholine esterase were followed in rat brain cerebral cortex, caudate, thalamus, hippocampus and medulla after i.v. administration of physostigmine. Both enzymes were found to be inhibited in a dose-dependent manner. The most pronounced inhibition of (Na+ + K+)-ATPase was found in caudate, where the highest activity of acetylcholine esterase is found.     

Ventral neural tube cells differentiate into hepatocytes in the chick embryo

A population of ventral neural tube cells has recently been shown to migrate out of the hind brain neural tube via the vagus nerve and contribute to the developing gastrointestinal tract. Since liver is also innervated by the vagus nerve, we sought to determine if these cells also migrate into the liver. Ventral neural tube cells in the caudal hindbrain of chick embryos were tagged with a replication-deficient retroviral vector containing the LacZ gene on embryonic day 2. Embryos were processed for detection of labeled cells on embryonic day 5 and 11. Labeled cells were seen in the liver on both days and identified as hepatocytes. Previously, it was believed that all hepatocytes develop from the gut endoderm. Results of the present study show an additional source for the formation of liver cells. Received 25 August 1998; received after revision 5 November 1998; accepted 5 November 1998     

Binding of cytophilic rabbit IgG to homologous hepatocytes.

Rabbit liver cells were able to bind cytophilic monomeric and polymeric homologous IgG via their Fc receptor binding sites (FcR). On the other hand, non-cytophilic rabbit IgG did not bind to hepatocytes, even after its aggregation. The present findings suggest that FcR on rabbit liver cells are specific for cytophilic monomeric IgG but do not significantly bind non-cytophilic, polymeric IgG.     

The effect of physostigmine on (Na++K+)-ATPase activity in different rat brain regions

Summary The activity of (Na⁺+K⁺)-ATPase and acetylcholine esterase were folloed in rat brain cerebral cortex, caudate, thalamus, hippocampus and medulla after i.v. administration of physostigmine. Both enzymes were found to be inhibited in a dose-dependent manner. The most pronounced inhibition of (Na⁺+K⁺)-ATPase was found in caudate. where the highest activity of acetylcholine esterase is found.These studies were supported by a grant from the Union of Science of Republic Serbia, No. 40404-14.     

Effect of physical exercise on the specific activity of carbonic anhydrase isozyme in human erythrocytes

Summary Significant decreases in the levels of both carbonic anhydrase type B and total esterase activity of human erythrocytes were observed after physical exercise (bicycle ergometer, 150 W for 30 min). Since carbonic anhydrase B-dependent esterase activity likewise decreased, the decrease in the total esterase activity would be caused by the decrease of carbonic anhydrase B activity. The specific activity of carbonic anhydrase B tended to decrease after the exercise. On the other hand no such effects were noted for carbonic anhydrase type C.     

Binding of cytophilic rabbit IgG to homologous hepatocytes

Summary Rabbit liver cells were able to bind cytophilic monomeric and polymeric homologous IgG via their Fc receptor binding sites (FcR). On the other hand, non-cytophilic rabbit IgG did not bind to hepatocytes, even after its aggregation. The present findings suggest that FcR on rabbit liver cells are specific for cytophilic monomeric IgG but do not significantly bind non-cytophilic, polymeric IgG.We thank Mrs Sanda Maghiar for her excellent technical assistance.     

Lipid accumulation in mouse hepatocytes after morphine exposure

Summary After morphine injection lipid accumulation in mouse hepatocytes begins within 2 h and continues for 24 h when most hepatocytes are filled with lipid droplets. In spite of morphine maintenance the liver recovers as the accumulated lipids are coupled with protein and subsequently transported and released into the perisinusoidal space of Disse.Supported by USPHS Grants GM 15490, 5 SO7 RR05386-16 and DA-01310.     

Recherches sur la pseudo-cholinestérase du sérum et la cholinestérase vraie des globules rouges

Summary By means of a technic published in this journal (2, 66 [1946]), it has been observed that the activity of the pseudo-choline esterase of the serum is highest in presence of high concentrations of acetylcholine.The true choline esterase of the red corpuscules has her optimal activity at concentrations of 200 mg % acetylcholine. This high activity of these choline esterase is only going on during 3 to 5 minutes; after this period an inhibition occurs. At lower substrate concentrations (50 mg % acetylcholine) the difference in activity in the first and second phase is becoming less pronounced and the curve of the choline esterase activity becomes a straight line. At the small substrate concentration (4 mg % acetylcholine) again a primary higher choline esterase activity has been observed.Choline inhibitsin vitro the activity of the choline esterase. Prostigmine inhibits alsoin vivo andin vitro, the choline esterase of serum and globules.