A histochemical study of myofiber types in the serratus ventralis thoracis muscle of sheep during growth

The objective of the research described herein was to describe the profile of histochemically determined myofiber types in serratus ventralis thoracis of the sheep at various stages of postnatal development. This muscle acts to suspend the trunk and to pull the anterior limbs back during locomotion. The results obtained allow comparison with other results in the literature on muscles with different functional demands of movement and postural activity. Three sheep were sacrificed at each of the following ages: birth, 2, 4, 8, 12 and 16 wk. One 52-mo-old sheep was used. The muscle was processed histochemically for a series of enzyme activities including myosin adenosine triphosphatase (ATPase). Type I myofibers reacted strongly for acid-stable myosin ATPase and negatively for alkali-stable ATPase. Type II myofibers showed the opposite reaction pattern. Various subtypes were classified on the basis of intermediate reaction patterns and on the basis of enzyme activities other than ATPase. Type II myofibers decreased greatly in proportion from birth to 4 wk of age and were essentially unchanged during further growth of the animal. Type I myofibers increased in proportion from birth to 4 wk, increased slightly from 4 to 12 wk and then underwent little further change. Intermediate types changed little from birth to 4 wk and decreased thereafter. Type II myofibers were greater in proportion than type I and intermediate myofibers were always lowest, regardless of age of animal.

Absence of the glycerol phosphate shuttle in the various zones of the growth plate

The various zones of the growth plate of the rib of six-week-old male New Zealand White rabbits were obtained by means of a specially devised guillotine slicing apparatus. Cartilage slices from each zone were assayed enzymatically for activity of glycerol phosphate dehydrogenase by an adaptation of a fluorimetric technique based on the conversion of non-fluorescent resazurin to the highly fluorescent resorufin in the presence of nicotinamide adenine dinucleotide and the enzyme. No glycerol phosphate dehydrogenase activity was detectable in any zone of the growth plate, whereas control liver slices exhibited abundant enzyme activity. Thus the glycerol phosphate shuttle, one pathway whereby reducing equivalents are carried or shuttled from cytoplasmic nicotinamide adenine dinucleotide to the intramitochondrial respiratory chain, is entirely lacking in growth-plate chondrocytes. The lack of this enzyme, and the absence of the glycerol phosphate shuttle, may explain the high rate of lactate accumulation in the presence of ample oxygen concentration (aerobic accumulation) even though the Krebs cycle (tricarboxylic acid cycle) and electron transport are proceeding at normal rates.

CLINICAL RELEVANCE

The growth plate is a complex structure whose metabolism is still not well understood. This study demonstrates that, in at least one metabolic pathway, the growth-plate chondrocyte does not resemble other normal cells. Only as we are able to formulate a more complete picture of the metabolism of the normal growth plate will be able to understand, and perhaps correct or prevent, those disease states in which growth-plate metabolism has bone away.

Effect of changes in thyroid status on tissue respiration in fetal and newborn sheep

The effect of both exogenous and endogenous changes in thyroid status on in vitro tissue respiration and thermogenic enzymes (sodium-potassium-adenosine triphosphatase and alpha-glycerophosphate dehydrogenase) was studied in fetal and newborn sheep. Oxygen consumption of liver and brain increased from 25 +/- 4.1 and 58.5 +/- 2.8 microliters O2 X 100 mg-1 X h-1, respectively, in tissues from unthyroidectomized fetal animals at 136-140 days gestation to 60 +/- 4.2 and 72 +/- 1.5 microliters O2 X 100 mg-1 X h-1 in tissues from unthyroidectomized newborn lambs between birth and 7 days of age. The physiological changes in thyroid function that normally occur at birth resulted in a mean (+/- SE) plasma triiodothyronine (T3) concentration of 563 +/- 39 ng/dl in the newborn lambs compared with 39 +/- 8 ng/dl in the fetal animals. Kidney respiration and thermogenic enzyme activities in the several tissues studied did not change. Liver, kidney, and brain respiration and thermogenic enzymes from T3-treated thyroidectomized fetal and newborn lambs were not increased (compared with untreated thyroidectomized animals) despite a marked increase in plasma T3 concentrations. Conclusions are that 1) liver, kidney cortex, and frontal brain cortex in the fetal and newborn lamb are relatively insensitive to the calorigenic effect of thyroid hormones, and 2) a perinatal increase in hepatic and cerebral respiration occurs in newborn animals (compared with fetal animals) but is probably not due solely to perinatal increases in thyroid hormones.

Effect of 5,5'-diphenylhydantoin on the activities of hepatic cytosol malic enzyme and mitochondrial alpha-glycerophosphate dehydrogenase in athyreotic rats

Since 5,5'-diphenylhydantoin (DPH) decreases specific nuclear receptor binding of T3, the possibility that DPH might affect thyroid activity was examined by measurement of the activity of rat hepatic cytosol malic enzyme (ME) and mitochondrial alpha-glycerophosphate dehydrogenase (alpha-GPD) after DPH administration. Groups of athyreotic rats, prepared by thyroidectomy and 131I administration, were injected with vehicle (V), DPH, T3, or a combined dose of DPH and T3 for 48 h. The rats were then killed, and liver fractions were prepared for the measurement of ME and alpha-GPD activities. Compared with the V group, DPH treatment resulted in a significant increase in mean ME activity in four experiments; the mean ME activity for all studies was 2.2-fold greater than that of the V group (P less than 0.001). A significant increase in mean alpha-GPD activity was not observed in DPH-treated rats. T3 treatment resulted in a mean 31.5-fold increase in ME activity and a 10.9-fold increase in alpha-GPD activity. The magnitude of T3 induction of both enzymes was substantially attenuated by simultaneous injection of DPH, to 54-66% of the activity induced by T3 alone (P less than 0.001). Pair-feeding a T3-injected group and the DPH plus T3 group did not result in a decrease in the activity of either enzyme. Moreover, the observed changes did not appear to result from alterations in enzyme determinations or from significant changes in cytosol or mitochondrial protein concentration, cytosol T3, or plasma glucose. Although DPH-induced changes in the fractional rate of enzyme metabolism cannot be excluded, it is possible that changes in enzyme activities observed after DPH injection resulted from an interaction between DPH and the nuclear T3 receptor. If so, based on the effects observed in the present studies, DPH might be classified as a partial thyroid agonist.

[Local blood flow and metabolism in a focus of cerebral crushing]

Study of ECoG, local cerebral circulation, and brain pO2 in 39 patients in the acute period of severe craniocerebral injury, as well as morphohistochemical measurements around the focus of crushing (in experiments) showed that the transitional zone is a risk zone because the "enzymatic death" of the tissue of this zone occurring at the moment of the injury predetermines extension of the areas of necrosis later on. The most effective measure is the removal not only of the detritus but also of the transitional zone of the focus within the range of tissue that had hardly suffered any changes and the inclusion of vasoactive and dehydration agents in the therapeutic complex.

Development of brown adipose tissue thermogenesis in the ovine fetus and newborn

Despite the importance of brown adipose tissue (BAT) in the regulation of thermogenesis and energy expenditure in both newborn and adult mammals, the functional ontogenesis of this tissue is largely unknown. In the present study, we describe the maturation of several aspects of BAT thermogenesis in fetal and newborn sheep. Cell respiration of brown adipocytes isolated from perirenal BAT was measured using a Gilson differential respirometer. Cells were isolated from four fetal animals at 121-124 days gestation (group 1), five fetal animals at 137-140 days gestation (group 2), and five newborns between birth and 4 days of age (group 3). In addition to basal oxygen consumption, in vitro cell respiration also was measured after the addition of norepinephrine (NE), (Bu)2cAMP, alpha-glycerophosphate (alpha GP), and butyric acid. Mean (+/- SEM) basal respiration (in microliters of O2 per 10(6) cells/h) increased from 11 +/- 1 in group 1 to 31 +/- 2 in group 2 and 45 +/- 7 in group 3. Cell volume increased from 9 +/- 1 pl in group 1 to 13 +/- 2 pl in group 2 and 18 +/- 2 pl in group 3. After adjustment for variations in basal respiration due to differences in cell volume, basal respiration in group 2 was greater than that in group 1 and equal to that in group 3. Maximal NE (10(-6) M)-stimulated respiration increased from 74 +/- 16 in group 1 to 294 +/- 47 in group 2. Maximal NE-stimulated respiration in group 3 (133 +/- 30) was less than that in group 2, but equal to that in group 1. (Bu)2cAMP-stimulated respiration increased from 51 +/- 12 in group 1 to 175 +/- 22 in group II, with no further increase in group III. Neither NE- nor (Bu)2cAMP-stimulated respiration varied significantly with cell volume. alpha GP substrate respiration demonstrated significant increases from group 1 to group 2, with another significant increase in Group 3. Butyric acid substrate respiration in group 1 was less than those measured in groups 2 and 3, while respiration values in groups 2 and 3 were equal. After adjustments for variations due to differences in cell volume, the patterns of development of both alpha GP and butyric acid substrate respiration were unaltered. The following conclusions were reached 1) Full maturation of BAT catecholamine-stimulated cellular respiration occurs before delivery near term in the ovine fetus. 2) In the neonatal lamb, a decrease in catecholamine-stimulated respiration occurs without a decrease in (Bu)2cAMP-stimulated respiration. This suggests that a decrease in BAT sensitivity to NE occurs after delivery at the receptor adenyl cyclase level. 3) The perinatal increase in alpha GP substrate respiration without an increase in butyric acid substrate respiration suggests that mitochondrial alpha-glycerophosphate dehydrogenase activity is increased. This was confirmed by measuring increased alpha-glycerophosphate dehydrogenase activity in crude BAT mitochondrial fractions in group 3 animals.

Increases in dihydronicotinamide adenine dinucleotide (NADH) content and alpha-glycerophosphate dehydrogenase activity in epidermal wound healing

Alterations in NADH content and NAD-dependent dehydrogenase activity were determined in regenerating epithelium during wound healing in young guinea pigs. Regenerating epithelium exhibited increased levels of NADH. The migratory and proliferative phases of epidermal wound healing were characterized by increases in glycolytic enzyme activities, including an increase in lactate dehydrogenase (LDH). The maturation phase of epidermal wound healing was characterized by a maximal increase in alpha-glycerophosphate dehydrogenase (GOPDH) activity. The contrasting changes in LDH and GOPDH activity suggest that increased levels of NADH are utilized first by LDH in glycolysis during epidermal migration and proliferation and then by GOPDH in triacylglycerol synthesis during epidermal differentiation.

An adipogenic serum factor in genetically obese rodents

The adipose conversion of 3T3-Li cells depends on a serum factor present in high amounts in fetal calf serum, which is heat stable and can be extracted from serum by ethanol precipitation. Sera of two genetically obese rodent species, fa/fa Zucker rats and C57Bl/KsJ-db/db mice, contain a high adipogenic activity which is very similar to that found in fetal calf serum. In contrast, sera of their lean siblings (Fa/Fa-Zucker rats and C57Bl/KsJ-+/+ mice) are devoid of adipogenic activity.

Effects of N-(4-methylbenzylthiocarbonyl)-L-phenylalanine (KF 1492), a new hypolipidemic drug, and clofibrate on lipids metabolism

The effects of N-(4-methylbenzylthiocarbonyl)-L-phenylalanine (KF 1492) on the intestinal lipid absorption, the biliary lipid composition and alpha-glycerophosphate dehydrogenase (GPD) activity have been investigated in rats in comparison with clofibrate. KF 1492 did not have inhibitory activity on intestinal absorption of cholesterol and triglyceride. In the KF 1492-treated group (100 mg/kg, 8 d), an increase of bile flow (25.9%) per g liver was observed. The increase of excretion of bile acids (29.9%), phospholipids (45.2%) and cholesterol (33.4%) due to the increase of bile flow was clearly observed but no significant change in the concentration of each lipid was observed. In clofibrate-treated group, the concentration of bile acids and cholesterol in bile was decreased and output of biliary phospholipids was increased. Approximately 5 to 10 times increase of GPD activity was observed in mitochondrial fraction of the KF 1492- or clofibrate-treated rats (0.25% (w/w) in rat chow, 3 weeks). Thus, the increased degradation and excretion of cholesterol to bile may explain the hypocholesterolemic activity of KF 1492.

Developmental regulation of glycerol-3-phosphate dehydrogenase synthesis in Drosophila

Methods have been developed to measure the synthesis of glycerol-3-phosphate dehydrogenase (GPDH) during the development of Drosophila melanogaster. In emerged adult flies, GPDH is a principal component of protein synthesis, comprising between 1 and 2% of the protein synthetic effort. This high relative rate of protein synthesis continues throughout adult life during a period of stable enzyme concentration. Therefore, it is evident that GPDH undergoes continual turnover. Analysis of GPDH synthesis in the adult segments reveals that this enzyme is synthesized in head, thorax, and abdomen. In 5-day-old flies, the relative rates of GPDH synthesis in the thorax and abdomen are similar. However, the concentration of GPDH in the thorax greatly exceeds that found in the abdomen. Therefore, it appears that the turnover rate of GPDH in the abdomen must be greater than the turnover rate of GPDH in the GPDH-containing cells (flight muscle) of the thorax. GPDH represents between 0.5 and 0.9% of the protein synthetic effort of larvae. The principle GPDH-containing tissue of larvae is fat body. The turnover of GPDH in larvae is similar to that in adult abdomen. This may be related to the concurrent presence of GPDH isozyme-3 in both tissues. Our studies indicate that the cell type-specific control of GPDH occurs at several levels.

Histochemical studies of acid proteoglycans and glycoproteins and activities of hydrolytic and oxidoreductive enzymes in the skin epidermis of the fish Blennius sanguinolentus pallas (Teleostei: Blenniidae)

In the epidermis of the fish Blennius sanguinolentus the histochemistry of complex carbohydrates and various oxidoreductases has been studied by means of a series of selected light microscopical techniques. The epidermis is endowed with three types of secretory cells namely, the mucous goblet cells, the superficial polygonal cells and the ionocytes, which provide protective functions in view of their involvement in the prevention of the skin epithelium from invading pathogens and in the osmoregulation processes respectively. The secretory substances of mucous goblet cells contain sulfated, carboxylated and neutral complex carbohydrates in addition to a glycoprotein with sialic acid terminal to galactose in its oligosaccharide chains. Activities of SDH, ICDH, MDH and G-6-PDH were studied, to elucidate some aspects of the correlated functions of the ionocytes which play a key role in the performance of the maintenance of the electrolyte pattern in the internal milieu of the skin. Differences in the intensity of various oxidoreductases are correlated with the extent of the activity of the epidermis for related to secretion of a mucous cover over the surface. Activity of the oxidoreductases is confined mainly to the basal and outer epidermal layers and this enzyme zonation is discussed with reference to the existence of the high turnover rate of the epithelial cells and both the proliferative and respiratory capabilities of the skin epithelium.

Thyroid state and mitochondrial population during cold exposure

Young rats exposed to the cold (4 degrees C) for 15-25 days exhibit remarkable modifications in their thyroid state and in the mitochondrial population of target organs such as liver. The serum total and free T3 levels more or less doubled (from 77 +/- 7 to 130 +/- 7 ng/100 ml and from 350 +/- 25 to 530 +/- 25 pg/100 ml, respectively) after 2 h of exposure while the serum total T4 levels underwent a limited and transitory increase; mitochondrial alpha-glycerophosphate dehydrogenase activity increased. On re-exposure to room temperature the thyroid state returned to normal. Cold exposure diminished the cellular volumes of hepatic cells, while the successive warm re-exposure increased the number of liver cells. The number of mitochondria per nucleus increased after 5 days of cold exposure and doubled after 10 days (from 1,200 +/- 120 to 2,400 +/- 130), while the mean protein content per organelles exhibited an exactly contrary trend. These results suggest that during cold acclimatization, the thyroid, the thyroid plays a role in inducing an augmentation of mitochondrial membrane surfaces per cell by stimulation of the mitochondrial protein synthesizing mechanism. At present, it is not possible to establish whether these effects are due to transcriptional modifications of the nuclear genome only or, more likely, to a dual action at nuclear and mitochondrial level.

Flavin-linked mitochondrial alpha-glycerophosphate dehydrogenase of Candida utilis

The 150-fold purification of the L-alpha-glycerophosphate dehydrogenase of Candida utilis electron-transport particles by very mild procedures is described. The active enzyme contains FAD, iron and copper. The function of the metals, if any, is not clear. Its molecular weight is about 5 X 10(5). The subunit composition is complex and remains unresolved because the enzyme is contaminated with protease(s). The activity of this enzyme is very low in Saccharomyces cerevisiae unless the cells are grown in glycerol. The NAD-dependent cytoplasmic alpha-glycerophosphate dehydrogenase is present in C. utilis but could not be demonstrated in glucose-grown S. cerevisiae.

Evaluation of the lipid-lowering activity of AY-25,712 in rats

The effect of AY-25,712 (2-methyl-2-phenyl-3(2H)-furanone-5-carboxylic acid) on serum lipids, hepatic lipogenesis and biliary cholesterol was investigated in male rats. Based on one-week treatment, the minimal effective dose of AY-25,712 which lowered serum triglycerides was 1 mg/kg/day, and LDL-cholesterol, 5 mg/kg/day. Nicotinic acid produced a similar lipid-lowering profile albeit at 5 times higher doses. AY-25,712 at doses of 2 mg/kg/day and higher significantly increased the ratio of HDL to total cholesterol. Unlike clofibrate, AY-25,712 did not increase liver weight or liver mitochondrial alpha-glycerophosphate dehydrogenase, nor increase biliary cholesterol levels in rats fed a diet containing 2% cholesterol and 0.5% cholic acid. AY-25,712 lowered serum cholesterol, triglycerides and phospholipids in rats rendered hyperlipidemic with Triton WR-1339 and decreased the elevated serum triglycerides in streptozotocin-diabetic rats. [14C]Acetate incorporation into cholesterol by liver homogenate was suppressed in rats given AY-25,712 p.o. for 1 week. The results show that AY-25,712 is a potent LDL-cholesterol- and triglyceride-lowering agent in rats, and that its lipid-lowering profile differs from that of clofibrate but resembles that of nicotinic acid.

Glycerolphosphate dehydrogenase, glucose-6-phosphate dehydrogenase, lactate dehydrogenase and carbonic anhydrase activities in oligodendrocytes and myelin: comparisons between species and CNS regions

Oligodendrocytes isolated from bovine white matter had higher specific activities of glycerolphosphate dehydrogenase (GPDH) and glucose-6-phosphate dehydrogenase (G6PDH) than were observed in homogenates of white matter or gray matter from bovine brains, whereas the activity of lactate dehydrogenase (LDH) was lower in the cells than in the homogenates. These observations suggest that G6PDH, as well as GPDH, is an oligodendrocyte-enriched enzyme. The 3 enzymes were also measured in myelin from bovine brains, rat spinal cords, and mouse brains, and, for each enzyme, the relative specific activity (RSA) in myelin was calculated by dividing the specific activity in myelin by the specific activity in the respective starting homogenate. Of the 3 enzymes, GPDH, G6PDH and LDH, the RSA of G6PDH was highest, at 0.26, in the bovine myelin, whereas the RSAs of GPDH were highest, at approximately 0.20, in the myelin from rat spinal cords and mouse brains. Carbonic anhydrase was also measured in the myelin from the rodent tissues, and significantly higher RSAs, at 0.43-1.06, were obtained. The finding that carbonic anhydrase consistently has higher concentrations than either G6PDH or GPDH in myelin suggests that the latter are restricted, in the myelin sheath, to regions in which oligodendroglial cytoplasm is enclosed, whereas carbonic anhydrase is distributed more broadly in the myelin membranes. A developmental increase in GPDH in the rat spinal cord is also reported.

Basal ganglia degeneration, myelin alterations, and enzyme inhibition induced in mice by the plant toxin 3-nitropropanoic acid

The plant toxin, 3-nitropropanoic acid, produced topographically and morphologically distinctive lesions in mice after daily intraperitoneal injections. In the lateral caudate-putamen there were bilateral and symmetrical lesions consisting of marked swelling and pyknosis of individual cells and processes in otherwise unaffected tissue. The appearance of transitional forms and the usual post-synaptic location of the swollen processes indicated that affected cells were neurons. A few mice exhibited a more diffuse spongy change in the lateral caudate-putamen that caused major architectural changes. In the globus pallidus, entopeduncular nucleus, and anterior substantia nigra pars reticulata there was fine spongy change of the neuropil that spared cell bodies, and was primarily due to swelling of dendrites. A third lesion pattern in myelinated tracts of the midbrain, medulla, and spinal cord consisted of adaxonal, intramyelinic cleft formation. Succinate dehydrogenase activities assayed in frozen brain sections and in isolated mitochondria were markedly reduced in intoxicated mice.

Sympathetic and thyroid influences on metabolic rate in fed, fasted, and refed rats

Twice daily subcutaneous injections of norepinephrine (NE, 25 micrograms/100 g body wt) for 16 days, in adults rats, produced significant increases in resting oxygen consumption (VO2), thermogenic responses to NE, plasma triiodothyrone (T3) levels, interscapular brown fat mass, and hepatic mitochondrial alpha-glycerophosphate dehydrogenase activity. These responses were absent in hypothyroid rats. Rats fasted for 72 h showed significant decreases in VO2 and plasma T3. Refeeding with carbohydrate (CHO, 40 kJ) produced a rapid rise in plasma T3 within 3 h and a delayed rise in VO2 (peak rise at 24 h). Treatment with the beta-adrenergic antagonist propranolol (2 mg/100 g body wt, sc) at the time of the meal blocked the rises in T3 and VO2. Injecting fasted rats with T3 (365 ng/100 g body wt, ip) had no effect on subsequent VO2 but NE (40 micrograms/100 g body wt, sc) produced similar increases in plasma T3 and VO2 to CHO refeeding. The delayed rise in VO2 after CHO refeeding was blocked by propranolol (0.5 mg/100 g body wt, sc) when given 24 h after the meal. These results provide evidence for catecholamine-induced changes in thyroid hormone metabolism and for a sympathetic involvement in thyroid-dependent responses to nutritional manipulations.

Coupling of proadipocyte growth arrest and differentiation. II. A cell cycle model for the physiological control of cell proliferation

Experimental evidence is presented that supports a cell cycle model showing that there are five distinct biological processes involved in proadipocyte differentiation. These include: (a) growth arrest at a distinct state in the G1 phase of the cell cycle; (b) nonterminal differentiation; (c) terminal differentiation; (d) loss of the differentiated phenotype; and (e) reinitiation of cell proliferation. Each of these events is shown to be regulated by specific human plasma components or other physiological factors. At two states designated GD and GD', coupling of growth arrest and differentiation is shown to occur. We propose that these mechanisms for the coupling of growth arrest and differentiation are physiologically significant and mimic the regulatory processes that control stem cell proliferation in vivo.

Evidence for glucocorticoid target cells in the rat optic nerve. Hormone binding and glycerolphosphate dehydrogenase induction

Biochemical evidence suggests that neuroglia are responsive to glucocorticoids, yet previous studies of glucocorticoid localization have typically failed to demonstrate significant uptake by neuroglial cells. To further investigate this problem, we measured glycerol-3-phosphate dehydrogenase (GPDH) activity and glucocorticoid receptor binding capacity in normal rat optic nerves and in those undergoing Wallerian (axonal) degeneration. Binding studies were also performed on hippocampus and anterior pituitary for comparison purposes. Normal optic nerve preparations possessed a high level of GPDH activity that was glucocorticoid-inducible and that increased further following axonal degeneration. Antibody inactivation experiments demonstrated the presence of more enzyme molecules in the degenerating nerve preparations. correlative immunocytochemical studies found GPDH-positive reaction product only in morphologically identified oligodendrocytes, a result that is consistent with the previously reported localization of this enzyme in rat brain. Optic nerve cytosol fractions displayed substantial high-affinity binding of both dexamethasone (DEX) and corticosterone (CORT) that, like GPDH, was elevated approximately two fold in degenerating nerves. Finally, in vivo accumulation of [3H]DEX and [3H]CORT by optic nerve and other myelinated tracts was examined using nuclear isolation and autoradiographic methods. Although neither steroid was found to be heavily concentrated by these tissues in vivo, a small preference for DEX was observed in the nuclear uptake experiments. These results are discussed in terms of the hypothesis that glial cells are targets for glucocorticoid hormones.

[Subcellular localization of some enzymes in silkworm eggs]

Differential centrifugation of the silkworm (Bombyx mori L.) egg homogenates resulted in nuclear, mitochondrial, lysosomal and cytosol infarctions, which were analyzed for the activities of alanine, aspartate- and tyrosine aminotransferases, 3-glycerophosphate- and lactate dehydrogenases and acid and alkaline DNAases. Alanine- and aspartate aminotransferases as well as 3-glycerophosphate dehydrogenase are localized mainly in the cytosol, where their activities made up to 86.2, 95.4 and 98.4% of their total activity, respectively. The activities of lactate dehydrogenase and acid DNAase are distributed between the nuclear and mitochondrial fractions; this distribution is even in the case of the former enzyme, whereas in the case of the latter the bulk (90.6%) of total enzyme activity is found in the nuclei. In contrast to the other enzymes whose activity is distributed between different cell fractions, tyrosine aminotransferase is localized exclusively in mitochondria, while alkaline DNAase--exclusively in the nuclei. No correlation between the level of enzyme specific activity and its total content in the fractions was established. The role of the enzymes under study in silkworm metabolism is discussed.

Lack of stimulation of renal (Na+ +K+)-ATPase by thyroid hormones in the rabbit

The effect of 1-3,5,3'-triiodothyronine (T3) and thyroxine (T4) on (Na+ +K+)-ATPase activities was examined in rabbit kidneys because in this tissue almost 80% of the metabolism is connected to active sodium transport. T3-receptor concentrations were estimated as 0.62 and 0.80 pmol/mg per DNA in the cortex and outer medulla, respectively. A dose of 0.5 mg T3/kg body weight for 3 days increased basal metabolic rate by almost 60%, and the mitochondrial 1-alpha-glycerophosphate dehydrogenase activity was increased by 50% in both the cortex and medulla. (Na+ +K+)-ATPase activity in the liver was raised by almost 50%. However, no changes in (Na+ +K+)-ATPase activities or binding sites for [3H]ouabain in either the kidney cortex or medulla could be observed. T4 at 16 mg/kg daily for 14 days was also without effect on renal (Na+ +K+)-ATPase activities. Furthermore, the response to T3 was absent at high sodium excretion rates induced by unilateral nephrectomy and extracellular volume expansion. Thus, despite stimulation of basal metabolic rate and renal 1-alpha-glycerophosphate dehydrogenase activity by T3 and T4, the (Na+ +K+)-ATPase activity in the rabbit kidney is identical in euthyroid and hyperthyroid states. However, thyroid hormones prevent the normal natriuretic response to extracellular volume expansion.

Tryptophan metabolism in alcoholic pellagra patients: measurements of urinary metabolites and histochemical studies of related muscle enzymes

Biochemical and enzymatic aspects of tryptophan-niacin metabolism were studied in 15 adult alcoholic pellagra patients and in 14 controls. In addition to the clinical signs of niacin deficiency, most of the pellagra patients had other signs of malnutrition. Plasma tryptophan in pellagra patients was 2.07 +/- 1.27 mumol/dl, and in the controls 4.84 +/- 2.21 mumol/dl (p less than 0.001). The erythrocyte glutamic oxaloacetic transaminase index was 1.94 +/- 0.77 in the pellagra patients and 1.58 +/- 0.73 in the controls. The urinary levels of 3-hydroxyanthranilic acid were 34.49 +/- 21.47 mumol/g of creatinine in the pellagra patients and 14.51 +/- 8.02 mumol/g creatinine in the controls (p less than 0.02). The urinary levels of N'methylinicotinamide were 2.13 +/- 1.18 mg/g creatinine in the pellagra patients and 4.76 +/- 1.94 mg/g creatinine in the controls (p less than 0.01). The excretion of N'-methyl-2-pyridone-5-carboxamide (2-pyridone) was 2.94 +/- 2.37 mg/g creatinine in the pellagra patients and 10.19 +/- 7.49 mg/g creatinine in the controls (p less than 0.01). The histoenzymological activity of 3-hydroxyanthranilate oxidase in the deltoid muscle was higher in the pellagra patients than in the controls, whereas alpha-glycerophosphate dehydrogenase activity was higher in the controls. These results suggest that for alcoholic pellagra patients the tryptophan-niacin pathway is inhibited after the 3-hydroxyanthranilate oxidase step.