Amelioration of some metabolic effects produced by hyperthyroidism in late pregnant rats and their fetuses. Effects on lipids and proteins.

We have studied the effect of 40-45 days administration of 1 mg/kg thyroxine on protein and lipid metabolism in liver, heart, lungs, kidneys and adrenal glands of virgin and 21-day pregnant rats and their fetuses and placentae. The chronic administration of thyroid hormone produced significant increases in serum T3 and T4 in both groups as well as in organ weights and protein concentrations in virgin rats, but much smaller modifications in pregnant ones. Hyperthyroidism decreased the weight of fetal livers and increased that of placentae; protein content was increased in all fetal organs. Hyperthyroidism induced increases in phospholipid concentrations in all the organs and in total lipids only in liver and heart of adult rats, which were not counteracted by pregnancy. Pregnant rats had increases in total lipids in liver and kidneys and in adrenal phospholipids. In hyperthyroid fetuses there was an increase in hepatic total lipids and no changes in phospholipids. Hepatic lipogenesis (measured by in vivo incorporation of 3H2O into lipids) was increased by hyperthyroidism in virgin and pregnant rats, but the increase was significantly smaller in the pregnant hyperthyroid rats compared with the virgin ones. Fetal lipogenesis in liver and lung was not changed. In addition, an increase was observed in lipogenic enzyme (fatty acid synthetase and glucose-6-phosphate dehydrogenase) activities in hyperthyroid virgin rats which was prevented by pregnancy. In fetuses only pulmonary glucose-6-phosphate dehydrogenase was increased when expressed in terms of tissue weight. Our results indicate that the metabolic effect of hyperthyroidism is attenuated in pregnant rats and their fetuses, when compared with adult virgin rats, in most of the parameters studied.(ABSTRACT TRUNCATED AT 250 WORDS)     

Pericardial delivery of omega-3 fatty acid: a novel approach to reducing myocardial infarct sizes and arrhythmias

O2-carrying fluids based on hemoglobin (Hb) are in various stages of clinical trials to determine their suitability as O2-carrying plasma expanders. Polymerized Hb solutions are characterized by their vasoactivity, low O2 affinity, oncotic effect, prolonged shelf life, and stability. Physiological responses to facilitated O2 transport after exchange transfusion with polymerized bovine Hb (PBH) were studied in the hamster window chamber model during acute moderate anemia to determine how PBH affects microvascular perfusion and tissue oxygenation. The anemic state [29% hematocrit (Hct)] was induced by hemodilution with a plasma expander (70 kDa dextran). After hemodilution, animals were randomly assigned to different exchange transfusion groups. Study groups were based on the concentration of PBH used, namely: PBH at 13 g Hb/dl [PBH13], PBH diluted to 8 (PBH8) or 4 (PBH4) g Hb/dl in albumin solution at matching colloidal osmotic pressure (COP), and no PBH (only albumin solution) at matching COP (PBH0). Measurement of systemic parameters, microvascular hemodynamics, capillary perfusion, and intravascular and tissue O2 levels was performed at 18% Hct. Restitution of O2-carrying capacity with PBH13 increased arterial pressure and triggered vasoconstriction, low perfusion, and high peripheral resistance. PBH4 and PBH0 exhibited lower arterial pressures compared with PBH13. Exchange transfused animals with PBH8 and PBH4 better maintained perfusion and functional capillary density than PBH13. Blood gas parameters and acid-base balance were recovered proportional to microvascular perfusion. Arterial O2 tensions were improved with PBH4 and PBH8 by preventing O2 precapillary release and increasing O2 reserve. Further studies to establish PBH optimal dosage, efficacy, safety, and its effect on outcome are indicated before Hb-based O2-carrying blood substitutes are implemented in routine practice.     

The effect of melaxen and valdoxan on the activity of the glutathione antioxidant system in rats with experimental hyperthyroidism

The activity of the glutathione system and conjugated diene content (CD) have been investigated in the liver and blood serum of rats with experimental hyperthyroidism treated with melaxen and valdoxan. The study of glutathione reductase (GR), glutathione peroxidase (GP) and glutathione transferase (GST) activities increased under this pathology has shown that administration of these compounds decreased these activities towards control levels. Melaxen and valdoxan administration increased reduced glutathione (GSH) content as compared with untreated hyperthyroid rats. This increase may be associated with its decreased utilization for detoxification of toxic products of free radical oxidation (FRO). Administration of the melatonin correcting drugs also tended to normalize the CD level increased in the liver and blood serum of hyperthyroid rats. Results of this study indicate that melaxen and valdoxan exhibit positive effect on free radical homeostasis. This appears to be accompanied by a decrease in the load of the glutathione antioxidant system in comparison with the examined pathology.     

Increased tissue PO2 and decreased O2 delivery and consumption after 80% exchange transfusion with polymerized hemoglobin

The O2-carrying blood substitute based on polymerized bovine hemoglobin (PBH) was used to determine efficacy in maintaining tissue Po2 after an 80% isovolemic blood exchange leading to a hematocrit of 19% [5.4 g Hb/dl from red blood cells (RBCs) and 6.3 g Hb/dl from PBH]. Effects were studied in terms of O2 delivery, O2 extraction, and tissue Po2 at the microcirculatory level at 1, 12, and 24 h after exchange transfusion in awake hamsters prepared with a window chamber model. At 1 h after exchange, arteriolar and venular diameters were decreased compared with baseline. Arteriolar diameter did not fully recover at 12 h after exchange, but venular diameter returned to normal. At 24 h after exchange, arteriolar and venular diameters were not different from baseline. Combining diameter and flow velocity data allowed us to calculate arteriolar and venular flows. At 1 h after exchange, arteriolar and venular flow was reduced compared with baseline. Arteriolar flow was lower at 12 h after exchange and recovered after 24 h. The number of capillaries with RBC passage [functional capillary density (FCD)] at 1 h after exchange with PBH was significantly lower than baseline. FCD remained decreased at 12 h; at 24 h after exchange transfusion, FCD was fully recovered. Tissue Po2 was maximal at 1 h after exchange and decreased progressively at 12 and 24 h after exchange. O2 release to the tissue was minimal at 1 h and increased at 12 and 24 h after exchange. These results suggest the impairment of tissue O2 metabolism after introduction of PBH into the circulation, which is mitigated as PBH concentration declines.     

Potentiation of humoral immune response and activation of NF-kappaB pathway in lymphocytes in experimentally induced hyperthyroid rats

This study explored the effect of hyperthyroid state on humoral immune response and NF-kappaB signaling in lymphocytes. Male Wistar rats were treated with l-thyroxin for four weeks. Animals were immunized with sheep red blood cells (SRBC) after three weeks of l-thyroxin treatment. After one week of immunization, serum anti-SRBC titer was measured and NF-kappaB signaling was studied in lymphocytes by Western blot analysis of p-IKB-alpha, IKB-alpha, and p65. These results were compared with that of control rats. Antibody response and density of p-IKB-alpha and p65 were significantly higher in l-thyroxin treated rats in comparison to controls. The antibody response was found to have significant correlation with density of p-IKB-alpha and p65. Our results indicate that NF-kappaB signaling pathway in lymphocytes is activated in hyperthyroid state which might play a role in potentiation of antibody response.     

Role of brain lactic acidosis in hypoxic depression of respiration

The role of lactic acidosis of progressive brain hypoxia (PBH) as both a central chemoreceptor stimulant and a general respiratory depressant was assessed by preventing lactate formation both locally and globally with dichloroacetate (DCA). Phrenic nerve activity (PN) and ventral medullary pH (Vm pH) responses to PBH (1% CO-40% O2-balance N2) were determined in anesthetized, paralyzed, peripherally chemodenervated, vagotomized cats while fraction of end-tidal CO2 (FETCO2) and mean arterial blood pressure (MABP) were maintained constant. Topical DCA near the central chemoreceptors prevented the progressive Vm acidosis of PBH and was associated with a slightly greater depression of PN for any given level of brain hypoxia [75 +/- 12% base-line mock cerebrospinal fluid compared with 63 +/- 11% base-line topical DCA at O2 content of arterial blood (CaO2) of 7.5 ml O2/dl]. Systemic DCA also prevented the progressive acidosis of PBH and significantly altered the profile of depression with PBH. Before DCA, PBH produced a progressive reduction in PN after reducing CaO2 by 20%. After DCA, PN was not significantly depressed until CaO2 was reduced to very low levels, whereupon there was a sharp decline in PN. Before DCA, reducing CaO2 to 6 ml O2/dl reduced PN by 41 +/- 16%, whereas after DCA there was no significant reduction in PN (4 +/- 5%). We conclude that 1) lactic acidosis near the central chemosensitive regions does produce a small stimulation of respiration during PBH but that 2) the overwhelming response to central lactic acidosis of PBH is respiratory depression.     

Effects of Altered Thyroid States on Myelinogenesis

Abstract: Myelinogenesis was studied in controls and in rats treated since birth with Methimazole (hypothyroid) or thyroxine (hyperthyroid). The amount of myelin in forebrain and its protein composition were determined between 13 and 40 days of age, the period of most rapid myelin accumulation. Hypothyroid rats had reduced body and brain weights relative to controls and the yield of myelin was reduced on both a per brain and a per milligram brain protein basis. Developmental changes in the protein composition of isolated myelin followed the pattern of control animals (the percentage of total myelin protein present as proteolipid protein, large basic protein, and small basic protein increased, as did the ratio of proteolipid/large basic protein) but were delayed temporally by 1–2 days. Hyperthyroid rats also had reduced body and brain weights. At 13 days myelin accumulation was greater than that of controls, corresponding to an earlier initiation of myelination. At later ages myelin yield was reduced on a per brain basis but not on a per milligram brain protein basis. The developmental pattern of myelin protein composition was accelerated temporally by 1–2 days. Myelination in optic nerve, assayed by proteolipid protein content, also was slightly delayed in hypothyroid animals and somewhat accelerated in hyperthyroid animals. The relative synthesis of myelin proteins (determined as incorporation of intracranially injected [³H]glycine into myelin protein relative to incorporation into whole brain protein), as well as distribution of radioactivity among individual myelin proteins, was determined. The results supported the conclusion of the myelin protein accumulation study; hypothyroidism retards the developmental program for myelinogenesis, whereas in the hyperthyroid state myelin synthesis is initiated earlier but is also terminated earlier.     

The level of major proteins and minerals in the blood serum of chickens fed diets with pure cellulose

The aim of the research was to determine the concentration of total protein and its fractions as well as the concentration of selected mineral components in the blood serum of male broiler chickens Cobb 500 fed diets with different cellulose content. Blood samples were collected for examination from the birds' pterygoid canal veins on their 42 day of age. There was no influence of cellulose preparation on the content of total protein and its fractions: albumins, alfa1-, alfa2-, beta-, gamma-globulins, albumin to globulin ratio, inorganic phosphorus, sodium, potassium, chloride and iron concentrations in blood serum. The highest calcium concentration (P < 0.05) was detected in the blood serum of males fed a diet with the highest cellulose content (0.75-0.95%). Simultaneously, a tendency of increased calcium content was observed along with an increased amount of pure cellulose in diets. The lowest magnesium level (P < 0.05) was observed in the blood of birds fed diets with the lowest amount of cellulose (0.25-0.45%). The magnesium level in the blood of birds fed a diet with higher amounts of cellulose did not considerably differ from the control group. Results from the current study suggest that introduction of a limited amount of pure cellulose into the diet of broiler chickens does not affect total protein concentration and protein fractions but can influence the mineral content in the blood serum.     

Cervical sympathetic and phrenic nerve responses to progressive brain hypoxia

To determine if depression of central respiratory output during progressive brain hypoxia (PBH) can be generalized to other brain stem outputs, we examined the effect of PBH on the tonic (tSCS) and inspiratory-synchronous (iSCS) components of preganglionic superior cervical sympathetic (SCS) nerve activity. Peak phrenic and SCS activity were measured in nine anesthetized, paralyzed, peripherally chemodenervated, vagotomized cats. PBH was produced by inhalation of 0.5% CO in 40% O2 while blood pressure and end-tidal CO2 were maintained constant. A progressive reduction in arterial O2 content from 14.3 +/- 0.6 to 4.5 +/- 0.3 vol% caused a 79 +/- 7% depression of peak phrenic activity and an 84 +/- 10% reduction of iSCS activity, but tSCS activity increased 42 +/- 21%. During CO2 rebreathing, iSCS activity increased in parallel with peak phrenic activity while tSCS activity was unchanged. The slopes of the CO2 responses of both phrenic (6.3 +/- 1.2%max/mmHg) and iSCS (4.6 +/- 0.8%max/mmHg) activity were unaffected by PBH. In four of nine hypocapnic and three of nine hypoxic studies, inspiratory activity in the SCS nerve was observed even after completely silencing the phrenic neurogram.(ABSTRACT TRUNCATED AT 250 WORDS)     

The carbohydrate component of immunoglobulin G peculiar to malignant growth

The total amount of carbohydrates and some carbohydrate components was studied in total preparations of immunoglobulins of blood serum of healthy people and cancer patients as well as in immunoglobulin G subfraction peculiar to cancer and in the fraction isolated from immunoglobulin G of healthy people blood serum corresponding to the place of column elution. An insignificant increase is established in the content of carbohydrates in the protein peculiar to cancer as compared to their amount in immunoglobulin G of blood serum from healthy people (1.93 and 1.46 g per 100 g of protein, respectively). A conclusion is drawn that the content of the studied substances in the protein peculiar to cancer cannot determine the peculiarities of its physicochemical, immunological and biological properties.     

Thyroid dysfunction modulates glucoregulatory mechanism in rat

The role of the thyroid gland in glucose homeostasis remains incompletely understood. To get a better insight hypo-and hyperthyroid conditions were experimentally induced in rat and found severe defects in glucose homeostasis. While blood glucose level returned to normal level after 2.5 hr of oral glucose challenge in control rats the blood glucose level remained high even after 24 hr of glucose load in both hypo- and hyperthyroid rats. These experimentally manipulated rats displayed higher levels of liver glycogen (10.45-22.8-fold) and serum glutamic pyruvic transaminase (1.48-9.8-fold). Liver histology of hyperthyroid treated rats revealed hepatotoxicity. From the results it can be concluded that thyroid gland plays an important role in glucose homeostasis.     

Oxidation products and antioxidant markers in plasma of patients with Graves' disease and toxic multinodular goiter: effect of methimazole treatment

Oxidative stress plays an important role in hyperthyroidism-induced tissue damage, as well as in development of autoimmune disorders. To clarify influence of thyroid metabolic status and autoimmune factors on blood extracellular indices of reactive oxygen species (ROS) generation and free radical scavenging in hyperthyroidism, we studied patients with newly diagnosed and untreated Graves' disease without infiltrative ophthalmopathy (17 female and 8 male, aged 41.8±8.9) and toxic multinodular goiter (15 female and 9 male, aged 48.4±10.1) under the same antithyroid treatment protocol. Initially and after achievement of stable euthyroidism with methimazole, plasma levels of hydrogen peroxide (H₂O₂), lipid hydroperoxides (ROOH) and ceruloplasmin (CP) and serum concentrations of thiobarbituric acid-reacting substances (TBARS) were determined. Similarly, activities of plasma superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR) were assayed. The results were compared to those of age- and sex-matched controls. Average duration of hyperthyroidism and treatment period were similar in both patients groups. H₂O₂, ROOH and TBARS concentrations were significantly higher in hyperthyroid patients compared to controls. Hyperthyroidism caused an evident increase in SOD and CAT activities and CP level, as well as a decrease in GPx and GR activities. Achievement of euthyroidism resulted in normalization of all analyzed parameters in both hyperthyroid patients groups. These findings suggest that the changes in blood extracellular indices of oxidative stress and free radical scavenging in hyperthyroid patients are influenced by thyroid metabolic status, and are not directly dependent on autoimmune factors present in Graves' disease.     

Phospholipid composition of oligodendroglial cells during normal development and in 18 day old hyperthyroid and malnourished rats.

The phospholipid composition of isolated oligodendroglial cell perikarya was studied in normal rats during development and in 18 day old malnourished and hyperthyroid rats. Phosphatidyl choline and phosphatidyl ethanolamine were found to be the major phospholipid constituents of oligodendroglial cells. Phospholipid content increased during development, mainly due to an increase of the above mentioned phospholipids. The major changes were observed in sphingomyelin, phosphatidyl serine, phosphatidyl inositol and phosphatidyl ethanolamine between 18 and 30 days of age. The phospholipid and protein content per cell was significantly decreased in the oligodendroglial cells isolated from malnourished rats as compared to controls. When data were expressed as a function of total proteins, the composition was similar to that of normal animals. In the hyperthyroid rats on the other hand, there were no changes in the amount of phospholipids per cell, while phospholipids per milligram of total oligodendroglial cell protein were markedly decreased. The changes in myelin composition produced by hyperthyroidism that we have previously described, do not follow closely those produced by this experimental condition in oligodendroglial cells, suggesting that the metabolism of myelin might be to a certain extent, independent of that in the parent cell.     

Nociceptive reaction-related state of glial intermediate filaments in the brain of rats with hyperfunction of the thyroid gland: An ontogenetic aspect

In experiments on Wistar rats of two age groups (5 weeks old and mature, 5 months old), we studied the content and polypeptide composition of glial fibrillary acidic protein (GFAP) in the cerebral cortex, hippocampus, thalamus, and brainstem under conditions of experimentally induced hyperfunction of the thyroid gland, as well as of combination of hyperthyroidism with the pain model (consequences of laparotomy). The hyperthyroid state was created by administration of L-thyroxine (initial dose, 10 μg/day) with food for 2 weeks; the dose was increased daily by 10 μg. At the end of experiment, we measured the level of thyroxine in the blood serum using an immunoenzymatic technique. We found that in the hyperthyroid state 5-week-old rats showed a significant increase in the content of filamentous GFAP fraction in the hippocampus, while when this influence was combined with the postoperation pain syndrome, an increase was observed in the brainstem (by 18 to 27%). Results of immunoblotting demonstrated that degraded polypeptides with a molecular mass of 47 to 45 kdalton were manifested under these conditions, which is indicative of intensification of cytoskeletal rearrangement of astroglia. In mature rats under the same conditions, we observed a drop in the level of insoluble polypeptides of intermediate filaments in astrocytes in the thalamus, hippocampus, and cerebral cortex. Neirofiziologiya/Neurophysiology, Vol. 38, No. 4, pp. 280–286, July–August, 2006.     

The effect of thyroxine on the calmodulin-dependent (Ca2+-Mg2+)ATPase activity and protein phosphorylation in rabbit fast skeletal muscle sarcolemma

Enzymatic properties and the protein pattern of sarcolemma fractions isolated from three groups of rabbits: euthyroid, hyperthyroid and hypothyroid, were studied. The amount of phosphorylated intermediate formed by the calmodulin-dependent (Ca2+-Mg2+)ATPase and the activity of this enzyme as well as that of (Na+-K+)ATPase were the highest in membranes isolated at the hyperthyroid state. On the other hand, sarcolemma obtained from the hypothyroid animals exhibited a decreased activity of (Na+-K+)ATPase, while the activity of calmodulin-dependent (Ca2+-Mg2+)ATPase was the same as in the preparations obtained from euthyroid animals. Thyroid hormones also changed the protein pattern of muscle sarcolemma. Membranes isolated from hyperthyroid animals lacked peptides of apparent molecular masses of 41 kDa and 53 kDa, while a peptide of the apparent molecular mass of 63 kDa was enriched in the preparation from hypothyroid animals. Thyroid hormones affected endogenous cAMP-dependent protein phosphorylation. The sarcolemma fraction obtained from hyperthyroid animals exhibited a decreased phosphorylation of peptides of apparent molecular masses of 30 kDa and 47 kDa, while the cAMP-independent phosphorylation of several other peptides was augmented. Moreover, sarcolemma preparations isolated from hyperthyroid animals showed higher activity of cAMP-independent protein kinase(s) and lower activity of cAMP-dependent protein kinase when compared to the euthyroid preparations. It is proposed that thyroxine increases the content of calmodulin-dependent (Ca2+-Mg2+)ATPase protein and affects the activity of cAMP-independent and cAMP-dependent protein kinases bound to sarcolemma.     

Effect of a protein-free diet on muscle protein turnover and nitrogen conservation in euthyroid and hyperthyroid rats.

Although protein turnover in skeletal muscle is increased in hyperthyroidism and decreased in hypothyroidism, a deficient protein intake tends to increase serum T3 (tri-iodothyronine) while decreasing muscle protein turnover. To determine whether this diet-induced decrease in protein turnover can occur independent of thyroid status, we have examined muscle protein turnover and nitrogen conservation in hyperthyroid rats fed on a protein-free diet. After inducing hyperthyroidism by giving 20 micrograms of T3/100g body wt. daily for 7 days, groups of euthyroid and hyperthyroid animals were divided into subgroups fed on basal and protein-free diets. Muscle protein turnover was measured by N tau-methylhistidine excretion and [14C]tyrosine infusion. Urinary nitrogen output of euthyroid and hyperthyroid animals fed on the protein-free diet was also measured. Although hyperthyroidism increased the baseline rates of muscle protein synthesis and degradation, it did not prevent a decrease in these values in response to protein depletion. Furthermore, hyperthyroid rats showed greatly decreased nitrogen excretion in response to the protein-free diet, although not to values for euthyroid rats. These findings suggest that protein depletion made the experimental animals less responsive to the protein-catabolic effects of T3.     

Oxidation Products and Antioxidant Markers in Plasma of Patients with Graves' Disease and Toxic Multinodular Goiter: Effect of Methimazole Treatment

Oxidative stress plays an important role in hyperthyroidism-induced tissue damage, as well as in development of autoimmune disorders. To clarify influence of thyroid metabolic status and autoimmune factors on blood extracellular indices of reactive oxygen species (ROS) generation and free radical scavenging in hyperthyroidism, we studied patients with newly diagnosed and untreated Graves' disease without infiltrative ophthalmopathy (17 female and 8 male, aged 41.8±8.9) and toxic multinodular goiter (15 female and 9 male, aged 48.4±10.1) under the same antithyroid treatment protocol. Initially and after achievement of stable euthyroidism with methimazole, plasma levels of hydrogen peroxide (H²O²), lipid hydroperoxides (ROOH) and ceruloplasmin (CP) and serum concentrations of thiobarbituric acid-reacting substances (TBARS) were determined. Similarly, activities of plasma superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR) were assayed. The results were compared to those of age- and sex-matched controls. Average duration of hyperthyroidism and treatment period were similar in both patients groups. H²O², ROOH and TBARS concentrations were significantly higher in hyperthyroid patients compared to controls. Hyperthyroidism caused an evident increase in SOD and CAT activities and CP level, as well as a decrease in GPx and GR activities. Achievement of euthyroidism resulted in normalization of all analyzed parameters in both hyperthyroid patients groups. These findings suggest that the changes in blood extracellular indices of oxidative stress and free radical scavenging in hyperthyroid patients are influenced by thyroid metabolic status, and are not directly dependent on autoimmune factors present in Graves' disease.     

Microvascular pressure and functional capillary density in extreme hemodilution with low- and high-viscosity dextran and a low-viscosity Hb-based O2 carrier

Blood losses are usually corrected initially by the restitution of volume with plasma expanders and subsequently by the restoration of oxygen-carrying capacity using either a blood transfusion or possibly, in the near future, oxygen-carrying plasma expanders. The present study was carried out to test the hypothesis that high-plasma viscosity hemodilution maintains perfused functional capillary density (FCD) by preserving capillary pressure. Microvascular pressure responses to extreme hemodilution with low- (LV) and high-viscosity (HV) plasma expanders and an exchange transfusion with a polymerized bovine cell-free Hb (PBH) solution were analyzed in the awake hamster window chamber model (n = 26). Systemic hematocrit was reduced from 50% to 11%. PBH produced a greater mean arterial blood pressure than the nonoxygen carriers. FCD was higher after a HV plasma expander (70 +/- 15%) vs. PBH (47 +/- 12%). Microvascular pressure spanning the capillary network was higher after a HV plasma expander (16-19 mmHg) compared with PBH (12-16 mmHg) and a LV plasma expander (11-14 mmHg) but lower than control (22-26 mmHg). FCD was found to be directly proportional to capillary pressure. The use of a HV plasma expander in extreme hemodilution maintained the number of perfused capillaries and tissue perfusion by comparison with a LV plasma expander due to increased mean arterial blood pressure and capillary pressure. The use of PBH increased mean arterial pressure but reduced capillary pressure due to vasoconstriction and did not maintain FCD.     

Enhanced cytochrome oxidase activity and modification of lipids in heart mitochondria from hyperthyroid rats

In order to further investigate the mechanism regulating the control of mitochondrial respiration by thyroid hormones, the effect of the hyperthyroidism on the kinetic characteristics of cytocrome c oxidase in rat heart mitochondria was studied. Mitochondrial preparations from both control and hyperthyroid rats had equivalent K_m values for cytochrome c, while the maximal activity of cytochrome oxidase was significantly increased (by around 30%) in mitochondrial rats. This enhanced activity of cytochrome oxidase was associated to a parallel increases in mitochondrial State 3 respiration. The hormone treatment resulted in a decrease in the flux control coefficient of the oxidase. The enhanced activity of cytochrome oxidase in hyperthyroid rats does not appear to be dependent on an increases in the mass of this enzyme complex in that the heme aa₃ content was equivalent in both hyperthyroid and control preparations. The Arrhenius plot characteristics differ for cytochrome oxidase activity in mitochondria from hyperthyroid rats as compared with control rats in the breakpoint of the biphasic plot is shifted to a lower temperature. Cardiolipin content was significantly increased in mitochondrial preparations from hyperthyroid rats, while there were no significant alterations in the fatty acid composition of cardiolipin of control and hyperthyroid preparations. The results support the conclusion that the enhanced cytochrome oxidase activity in heart mitochondrial preparations from hyperthyroid rats is due to a specific increase in the content of cardiolipin.     

Electrophoretic and enzymatic analysis of glycosaminoglycans in the blood serum of patients with hyperthyroidism

An effect of hyperthyroidism on the composition and levels of glycosaminoglycans in the blood serum was studied. Glycosaminoglycans isolated from 1-ml blood samples were assayed with the following techniques: carbazole, electrophoretic and enzymatic. Separation and assay of particular GAG were made with bidirectional electrophoresis. Isomers of the remaining chondroitin sulphates were assayed enzymatically. Electrophoretograms of GAG in blood serum of healthy women have shown two fractions: low sulphate chondroitin sulphate and chondroitin-4-sulphate. The same fractions of GAG were found in blood serum of the female patients with hyperthyroidism. Mean concentration of GAG in the blood serum of hyperthyroid patients increased by 51%: low sulphate chondroitin sulphate and chondroitin-4-sulphate concentrations increased by 22% and 190% respectively. Chondroitin sulphates in the blood serum of both groups were degraded to unsaturated disaccharides not containing sulphur and unsaturated 4-sulphate disaccharides. Concentrations of unsaturated 4-sulphate and unsaturated sulphur-free disaccharides increased by 71% and 17% in hyperthyroidism. Observed changes in the blood serum GAG concentrations reflect changes in the connective tissue metabolism in hyperthyroidism.