Effect of ethanol on protein synthesis in the tissues of various organs of guinea pigs

Long-term administration (for three months) of ethanol has been studied for its effect on the composition and synthesis of electrophoretic fractions of soluble proteins of the liver, brain, heart, kidneys and adrenals tissues in the guinea pigs. The obtained data permit supposing that the quantitative redistribution of the fractions under study as influenced by ethanol is due to their aggregation. Most of the studied tissues demonstrate a decrease in specific radioactivity of total proteins and 5 of 8-9 recorded electrophoretic fractions. Only one fraction in the heart and brain has been characterized by an increase of the protein synthesis level. The authors' results and data from literature make it possible to conclude that while analyzing pathogenesis of the chronic intoxication by ethanol and alcoholism the quantitative redistribution of soluble proteins and suppression of their synthesis in various tissues should be taken into account.     

Experimental hypovitaminosis D in guinea pigs administered different amounts of vitamin C

The experimental model of D-hypovitaminosis is first obtained on guinea pigs. It is established that the least degree of its manifestation is determined under conditions of the optimal supply of the organism with vitamin C. The necessity of using ascorbic acid in a complex of rachitis prophylaxis measures is substantiated.     

The microsomal ethanol oxidizing system: its role in ethanol and xenobiotic metabolism

After chronic ethanol consumption, the activity of the microsomal ethanol-oxidizing system (MEOS) increases and contributes to ethanol tolerance, as most conclusively shown in alcohol-dehydrogenase-negative deermice. In man and animals, there is an associated rise in microsomal cytochrome P-450, including a specific form (P-450IIEI) with high affinity for ethanol and for the activation of some drugs (i.e. acetaminophen), carcinogens (i.e. N-nitrosodimethylamine) and hepatotoxic agents (i.e. CCl4), thereby contributing to the susceptibility of alcoholics to xenobiotics, including industrial solvents. In addition, a benzoflavone-inducible liver cytochrome P-450 isoenzyme distinct but catalytically similar to cytochrome P-450IIE1 was purified which may play a significant role in drinkers who also are heavy smokers. Cross-induction of other microsomal enzymes is associated with enhanced metabolism of various drugs, resulting in drug tolerance. Catabolism of retinol was also found to be accelerated, in part through activation of newly discovered vitamin A depletion and possibly toxicity. Thus, elucidation of the microsomal metabolism of ethanol explains a number of complications that develop in alcoholics.     

Distribution of newly synthesized amylase in microsomal subfractions of guinea pigs pancreas

Amylase distribution was studied in guinea pig pancreas microsomes fractionated by centrifuging, for 2 hr at 57,000 g in a linear 10 to 30% sucrose gradient, a resuspended high speed pellet obtained after treating microsomes with 0.04% deoxycholate (DOC).¹ Amylase appeared in the following positions in the gradient: (a) a light region which contained ∼35% of total enzymic activity and which coincided with a monomeric ribosome peak; (b) a heavy region which contained ∼10% of enzymic activity in a sharp peak but which had very little accompanying OD₂₆₀ absorption; (c) a pellet at the bottom of the centrifuge tube which contained ∼20% of the enzymic activity. After 5 to 20 min'' in vivo labeling with leucine-1-C¹⁴, radioactive amylase was solubilized from these three fractions by a combined DOC-spermine treatment and purified by precipitation with glycogen, according to Loyter and Schramm. In all cases, the amylase found in the pellet had five to ten times the specific activity (CPM/enzymic activity) of the amylase found in the light or heavy regions of the gradient. The specific radioactivity (CPM/mg protein) of the proteins or peptides not extracted by DOC-spermine was similar for all three fractions. Hypotonic treatment of the fractions solubilized ∼80% of the total amylase in the fraction from the heavy region of the gradient, but only ∼20% of the amylase in the monomer or pellet fraction. Electron microscope observation indicates that the monomer region of the gradient contained only ribosomes, that the heavy region of the gradient contained small vesicles with relatively few attached ribosomes, and that the pellet was composed mostly of intact or ruptured microsomes with ribosomes still attached to their membranes. It is concluded from the above, and from other evidence, that most of the amylase activity in the monomer region is due to old, adsorbed enzyme; in the heavy region mostly to enzyme already inside microsomal vesicles; and in the pellet to a mixture of newly synthesized and old amylase still attached to ribosomes. Furthermore, the ribosomes with nascent, finished protein still bound to them are more firmly attached to the membranes than are ribosomes devoid of nascent protein.     

The microsomal ethanol oxidizing system mediates metabolic tolerance to ethanol in deermice lacking alcohol dehydrogenase

Metabolic tolerance to ethanol has been attributed to enhanced mitochondrial reoxidation of reducing equivalents produced in the alcohol dehydrogenase (ADH) pathway or to non-ADH mechanisms. To resolve this issue, deermice lacking low Km hepatic ADH were fed for 2 weeks a liquid diet containing ethanol or isocaloric carbohydrate and hepatocytes were isolated. Ethanol (50 mM) oxidation increased (9.8 vs 4.5 nmol/min/10(6) cells in controls). To differentiate which of two non-ADH pathways (the microsomal ethanol oxidizing system (MEOS) or catalase) was responsible for the induction, four approaches were used. First, MEOS was assayed in hepatic microsomes and found to be increased (24.4 vs 6.8 nmol/min/mg protein in controls). Second, hepatocyte ethanol metabolism was measured after addition of the catalase inhibitor azide (0.1 mM) and found to be unchanged. By contrast, the competitive MEOS inhibitor, 1-butanol, depressed metabolism in a concentration-dependent manner. A third approach relied on measurement of isotope effects known to be different for MEOS and catalase. From the isotope effect values, MEOS was calculated to contribute 85% or more of total ethanol oxidation by cells from both ethanol-fed and control animals. A fourth approach involved in vivo pretreatment with pyrazole (300 mg/kg/day for 2 days), which reduced peroxidation by catalase to 13% of control values in liver homogenates while inducing MEOS activity to 152% of controls. Hepatocytes from pyrazole-treated deermice showed a 47% increase in ethanol metabolism, paralleling the MEOS induction and contrasting with the catalase suppression. These results indicate that since metabolic tolerance occurs in the absence of ADH, it is not necessarily ADH mediated, and further, that MEOS rather than catalase accounts for basal ethanol metabolism and its increase after chronic ethanol treatment.     

The differentiation of rhythmogenic characteristics of the ureter's different regions in guinea pigs

Characteristics of rhythmogenic pacemakers of the ureter's perirenal middle and peribladder region morphologically and electrophysiologically are analysed in guinea pigs both in presence of spreading activity and breach of conductivity. It was shown that the action potential's amplitude of the middle region is the highest and duration of the spike activities from perirenal zone is maximal and all three regions are characterised by different functional conditions.     

Permeability of biological barriers of the endocrine organs to serum proteins in guinea pigs

The experiments on guinea-pigs have established that the vessels of endocrine organs are permeable for autogenic and heterogeneous serum proteins. Parenchymatous cells of these organs play the role of barriers for serum proteins. These parenchymatous cells are responsible for the type of barrier in each endocrine organ.     

A microsomal fraction of cryptococcus neoformans induces lymphocyte blastogenesis in infected guinea pigs

Differential centrifugation of a homogenate from a mechanically disrupted, acapsular isolate of Cryptococcus neoformans resulted in a 105 000 X g supernatant (105 K) and a microsomalfraction (MS), both of which were capable of eliciting specific delayed cutaneous hypersensitivity and in vitro blastogenesis in infected guinea pigs. Polyacrylamide gel electrophoresis revealed two major proteins in the MS and seven proteins in the 105 K fractions. Electron microscopy of the MSshowed both membranes and ribosomes. In vitro lymphocyte blastogenesis elicited by 1 to 10 g/ml of antigens was maximal after 4 days of incubation; the reacting populations were peripheral blood leukocytes (PBL) and peritoneal exudate cells (PEC). Spleen cells of infected animals were unresponsive to in vitro antigenic stimulation. A simplified schedule of priming animals was infection with a single dose of virulent cryptococci. Under these conditions 3 of 6 animals' PBL responded with stimulation ratios of 6.55, 21.1, 35.42 to the MS and 1.41, 9.33, 17.39 to the 105 K antigens at l ug/ml. Four of six animals' PEC response were positive with stimulation ratios of 2.62, 2.72, 4.02 and 7.20 towards MS, and 2.62, 5.13, 5.71, 10.01 to the 105 Kantigens at 1 g/ml. When small capsule and large capsule isolates were used for infection, the small capsule form was not isolated from the brain, in contrast to its isolation from 2 of 3 animals receiving large capsule forms. Two of three animals in each group responded with blastogenic indices more vigorous in the PBL, and the most potent antigen was MS. There was no obvious difference in lymphocyte reactivity between the two groups.Use of trade names is for identification only and does not constitute endorsement by the Public Health Service or by the U.S. Department of Health and Human Services.     

Activity of microsomal heme oxygenase in liver and spleen of ascorbic acid-deficient guinea pigs

Hepatic heme oxygenase activity was significantly altered in vitamin C-deficient guinea pigs. It was increased two-fold after 14 days and was decreased by 20% after 21 days of deprivation of the vitamin (always in comparison with the control value). The apparent Km of the enzyme was also altered in the course of ascorbic acid deficiency. The data of hepatic heme oxygenase activity correspond to previous results on the metabolism of hepatic cytochrome P-450 in different stages of ascorbic acid deprivation. Splenic heme oxygenase activity decreased progressively arriving at 50% of the control value after 21 days of vitamin C omission, its apparent Km remained unaltered.     

Zinc status and peripheral nerve function in guinea pigs

Guinea pigs fed a diet low in zinc develop clinical signs of apparent neurological origin. The signs include abnormal posture and locomotion as well as hypersensitivity to touch. In this study, electrophysiological and biochemical measurements were made on sciatic nerves from zinc-deficient and repleted animals as well as on controls fed either ad libitum or restricted to maintain weight comparable to those consuming the deficient diet. Both in vivo and in vitro measurements showed decreased motor nerve conduction velocity (NCV) in nerves of deficient animals. A longitudinal study showed excellent correlation of NCV and severity of clinical signs. Nerves from zinc-deficient guinea pigs had decreased Na,K-ATPase activity, but the number of sodium channels, as determined by saxitoxin binding, was not affected. It was concluded that the clinical signs of neuropathy in zinc deficiency are associated with impaired NCV and decreased Na,K-ATPase activity of peripheral nerves. The zinc-deficient guinea pig provides a useful model to study the biochemical defect in a peripheral neuropathy.