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Biomedical subjects

J Turinsky

Publications and source records attributed to J Turinsky.

At least 37 records · Page 2Linked to original sources
PubMed1986

Prostaglandin E2 and muscle proteolysis: effect of burn injury and cycloheximide.

Rats were subjected to a single hindlimb scald, and 3 days later soleus muscles from the burned and contralateral unburned hindlimbs were studied in vitro. Burned limb muscle released 354% more prostaglandin E2 (PGE2) and 119% more tyrosine than the contralateral uninjured counterpart. Neither the rate of net proteolysis in the uninjured muscle nor the stimulated net proteolysis in the burned limb muscle could be reduced by 90% inhibition of PGE2 production with aspirin or indomethacin. Inhibition of tissue protein synthesis with 5 X 10(-5) M cycloheximide stimulated tyrosine release by soleus muscles of both hindlimbs, but the increment in the burned limb muscle was 167% greater than in the contralateral uninjured counterpart. Concomitantly, cycloheximide decreased PGE2 releases by injured and uninjured muscles 90 and 73%, respectively. This previously unrecognized action of cycloheximide was investigated in soleus muscles of normal uninjured rats. It was found that 1 X 10(-6) M cycloheximide produces a 70% inhibition of muscle PGE2 release and increasing the concentration of inhibitor up to 500-fold does not further decrease PGE2 production. Cycloheximide acts by reducing the availability of endogenous arachidonic acid for PGE2 synthesis.

Animals↗
PubMed1986

Phospholipids, prostaglandin E2, and proteolysis in denervated muscle.

Soleus muscles of rats were studied up to 16 days after sciatic nerve transection. At the end of this period the denervated soleus muscles exhibited decreased content of diphosphatidylglycerol (-44%), normal level of phosphatidylethanolamine, and increased contents of phosphatidylcholine (+24%), sphingomyelin (+48%), lysophosphatidylcholine (+110%), phosphatidylinositol (+37%), and phosphatidylserine (+40%) per milligram of tissue protein. In studies in vitro, prostaglandin E2 (PGE2) release and tyrosine release by denervated soleus muscles were 319 and 141%, respectively, greater than those of sham muscles. An almost complete inhibition of PGE2 release with 5 X 10(-4) M aspirin or 2.8 X 10(-6) M indomethacin had no effect on tyrosine release of sham muscles or the stimulated tyrosine release of the denervated muscles. Addition of 5 X 10(-5) M cycloheximide in the medium resulted in 63% inhibition of PGE2 release by both groups of muscles; concomitant absolute increments in tyrosine releases by denervated and sham muscles did not statistically differ. In the presence of both 5 X 10(-5) M cycloheximide and 5 X 10(-4) M aspirin in the medium, PGE2 production by denervated and sham muscles was inhibited 87% while tyrosine release of denervated muscles was 108% higher than that of sham animals. It is concluded that 1) atrophy of denervated soleus muscle is associated with stimulated activity of tissue phospholipase A2, increased production of prostaglandin E2, increased total proteolytic rate, and unchanged rate of protein synthesis; 2) acute inhibition of PGE2 production does not inhibit the stimulated proteolysis in denervated muscle; and 3) cycloheximide inhibits PGE2 production by muscle.

Animals↗
PubMed1985

Prostaglandin E2 and muscle protein turnover in Pseudomonas aeruginosa sepsis.

Rats were injected intraperitoneally with Pseudomonas aeruginosa (septic group) or sterile 0.9% NaCl (controls). Soleus muscles were excised 7 h later, and muscle prostaglandin E2 release and tyrosine release were measured in vitro. Muscles of septic rats exhibited 226-326% higher release of prostaglandin E2 and 54-84% higher net proteolysis than muscles of controls. Inclusion of aspirin or indomethacin in the incubation medium almost completely inhibited prostaglandin E2 production, but had no effect on net proteolysis in muscles from either group. Inclusion of cycloheximide, a protein synthesis inhibitor, increased tyrosine release of control muscles by 42%, whereas no statistically significant increase was observed in muscles from infected rats. However, total proteolytic rate, indexed by tyrosine release in the presence of cycloheximide, was 22% higher in muscles of septic rats compared to that of control animals. Concomitantly, inclusion of cycloheximide inhibited prostaglandin E2 release by muscles of infected rats by 91% and that of controls by 65%. It is concluded that muscles of septic animals exhibit a pronounced stimulation of prostaglandin E2 release and net proteolysis, combined with a small increase in total proteolytic rate, the stimulation of net proteolysis is mainly due to inhibition of protein synthesis, the increases in net and total proteolysis appear to be independent of prostaglandin E2 production, cycloheximide has a previously unrecognized inhibitory effect on muscle prostaglandin E2 production.

Animals↗
PubMed1985

Inhibitors of protein synthesis, puromycin and emetine, inhibit prostaglandin E2 release by skeletal muscle.

Addition of 1 microM puromycin or 1 microM emetine to rat soleus muscle in vitro decreases muscle prostaglandin E2 release by 51-77%. This inhibition appears to be caused by decreased availability of endogenous arachidonic acid for prostaglandin E2 synthesis, because neither puromycin nor emetine inhibits muscle prostaglandin E2 production from arachidonic acid added into the incubation medium.

Animals↗
PubMed1985

Phospholipid and adenine nucleotide metabolism in muscle after burn injury.

The role of phospholipid and adenine nucleotide metabolism in postburn unresponsiveness of muscle to insulin was examined. A single hindlimb scald in the rat was produced, and 3 days later soleus muscles were incubated in vitro with and without insulin. Under basal conditions muscles from the burned limbs had normal contents of phosphatidylcholine and phosphatidylinositol but decreased diphosphatidylglycerol (-39%) and phosphatidylethanolamine (-24%) and increased sphingomyelin (+62%), lysophosphatidylcholine (+68%), and phosphatidylserine (+13%) compared with the contralateral unburned limb. Such muscle also incorporated 107-396% more [32P]phosphate into all measured phospholipids, except for diphosphatidylglycerol. The presence of insulin had no effect on either the mass of phospholipids or 32P incorporation in any muscle. The burned limb muscles (frozen in situ) also exhibited lower levels of ATP (-25%) and total adenine nucleotides (-24%) than uninjured muscle but normal adenylate energy charge. The burned limb muscles had lower adenosine (-37%), but inosine and hypoxanthine were 82 and 39% higher, respectively. These data suggest recovery of muscle from local thermal injury is associated with alterations in mass, and possibly also turnover, of tissue phospholipids, the measured phospholipids do not mediate the postreceptor action of insulin in normal muscle, energy charge of the recovering injured muscle is restored before ATP level at the time when this muscle is unresponsive to insulin stimulation.

Adenine Nucleotides↗
PubMed1984

Altered protein kinetics in vivo after single-limb burn injury.

Recovery from burn injury is associated with stimulated whole-body protein turnover. Since skeletal muscle and liver are the tissues most likely to influence whole-body measurements, we studied protein kinetics in soleus and plantaris muscles as well as liver 3 days after a 3 s burn on one hindlimb of the rat. Muscles from both the burned and unburned limbs of burned rats were compared with those of uninjured controls to distinguish between local and systemic factors involved. The following measurements were performed: (1) fractional growth rate of the tissue protein pool, determined from tissue protein content on days 2, 3 and 4; (2) fractional protein-synthetic rate, measured by [14C]tyrosine constant infusion on day 3; (3) fractional protein-degradation rate, calculated from the difference between the rates of protein synthesis and growth. Protein growth by soleus and plantaris muscles of control rats and unburned limb of burned rats was not paralleled by those in the burned limb, which showed progressive atrophy between 2 and 4 days post-burn (P less than 0.005). Protein synthesis by soleus but not plantaris muscle in the unburned limb of burned rats was enhanced by 62% (P less than 0.04) above control. Protein synthesis by burned-limb soleus and plantaris muscles was elevated by 114% (P less than 0.001) and 67% (P less than 0.02) respectively above control. Protein degradation by both soleus and plantaris muscles in the unburned limb of burned rats did not differ from control. In contrast, that of soleus and plantaris muscles in the burned limb was stimulated by 230% (P less than 0.001) and 164% (P less than 0.001) respectively compared with controls. Protein turnover of soleus muscles in both control and burned rats was more rapid than in corresponding plantaris muscles. Liver protein mass exhibited steady growth in control rats, but remained unchanged in burned animals between 2 and 4 days post-burn. Liver protein synthesis in burned rats was elevated by 56% (P less than 0.01) and protein breakdown was stimulated by 61% (P less than 0.002) above those of controls. The data indicate that both local and systemic factors influence tissue protein turnover in animals recovering from a single-hindlimb scald.

Animals↗
PubMed1984

Biochemical and functional alterations in macrophages after thermal injury.

Biochemical and functional measurements of rat pulmonary alveolar macrophages were measured 4 h after 1 10-s, 26 to 28% total body surface area, full-thickness scald burn induced under ether anesthesia. Both phagocytic activity and capacity were significantly decreased to a comparable extent, whereas microbicidal activity was increased almost twofold in macrophages from the burned animals. Concurrent with the decreased phagocytic function was a marked impairment in chemotaxis and random migration of these cells when zymosan-activated serum was used as the chemoattractant. When biochemical parameters were examined, it was demonstrated that, on a per-cell but not total-protein basis, alveolar macrophages from burned animals had elevated levels of RNA, total protein beta-glucuronidase, acid phosphatase, and 5'-nucleotidase. These results raise the possibility that the increased pneumonitis in burned individuals may be due to more complex macrophage dysfunctions than impaired microbicidal activity, as was once thought. Alternatively, the biochemical and functional changes observed may be a reflection of a new population of macrophages appearing in the lungs after thermal injury.

5'-Nucleotidase↗
PubMed1982

Effect of thermal injury on glucocorticoid and androgen binding in skeletal muscles with different fiber populations.

The role of glucocorticoids and androgens in postburn augmentation of skeletal muscle proteolysis was investigated following a 3-second single hindlimb scald (6 to 7% body surface area) in the rat. Soleus muscles and calf muscles from the burned and unburned hindlimbs were excised 3 days postburn and compared to age-matched controls to evaluate both the local and systemic effects of burn injury. Free tyrosine content in soleus and calf muscles of the burned limb was 30% and 58%, respectively, higher than in corresponding control muscles. Net proteolysis in burned limb soleus muscles, as measured by tyrosine "production' in vitro, was more than doubled as compared to controls. In contrast, tyrosine content and production by muscles from the unburned limb of burned rats dis not differ from controls. Specific binding of the glucocorticoid dexamethasone in cytosols of burned limb soleus and calf muscles was more than 80% below control level. Soleus muscles from the unburned limb of burned rats showed a 60% decrease in dexamethasone binding but that of the unburned limb calf muscles did not differ from controls. The latter difference and the observation in control rats of a relatively lower dexamethasone binding in calf muscles as compared to soleus muscles suggest that the glucocorticoid binding could be influenced by the type of fibers comprising the muscle. Unlike the glucocorticoid binding, neither the thermal injury nor the muscle fiber type had a significant effect on specific cytosolic binding of the androgen methyltrienolone by the muscle tissues studies. It is concluded that thermal injury restricted to one hindlimb leads to regional differences in skeletal muscle proteolysis and glucocorticoid binding. Muscles of the burned region exhibit stimulation of proteolysis and virtual disappearance of cytosolic glucocorticoid receptors. Muscles from the unburned region appear to have a normal rate of proteolysis and either normal or decreased glucocorticoid binding. It remains to be elucidated whether the decrease in cytosolic glucocorticoid receptors is due to changes in receptor synthesis and degradation, or to accelerated translocation of the receptors into the nucleus.

Androgens↗
PubMed1981

Impaired mineral metabolism in postburn muscle.

Rats were scalded on one hind limb and sacrificed by exsanguination at 4 hours, 1 day, and 3 days postburn. Concentrations of sodium, potassium, calcium, magnesium, and phosphate were measured in serum and in calf muscles from the burned and unburned limb of burned rats and controls. At 4 hours postburn, the injured rats exhibited a 5.4% elevation in serum potassium, a 23% increase in serum magnesium, and a 15% rise in serum phosphate compared to controls. At 3 days postburn, serum calcium and phosphate levels of burned rats were 7 and 13%, respectively, below controls. Tissue electrolytes in calf muscles from the unburned limb of burned rats did not differ from controls. In contrast, calf muscles of the burned limb showed up to a 202% increase in sodium content and up to a 61% fall of potassium content; the tissue Na/K ratio was elevated more than threefold at all test times. Burned muscles' calcium content was increased 127% at 4 hours, 112% at 1 day, and 21% at 3 days postburn. Magnesium and phosphate contents did not differ from controls at 4 hours postburn, but gradually decreased 58 and 59%, respectively, during the observation period. The data suggest that muscles underlying the burned wound show increased cell permeability and/or impaired active ion transport. These alterations as well as the loss of magnesium and phosphate may be related, in part, to the previously demonstrated depletion of ATP and adenine nucleotides in thermally injured muscles.

Animals↗
PubMed1981

Local effect of thermal injury on skeletal muscle blood flow and nucleotide levels.

We have previously shown that 3 days following a 3-sec scald of one hind limb, in vitro glucose utilization was markedly increased in soleus muscle from the burned limb but not in soleus from the contralateral unburned limb. The aim of the present study was to evaluate factors that might contribute to this local metabolic alteration. Three days following a 3-sec scald of one hind limb of the rat, blood flow through soleus and gastrocnemius muscles of the burned limb as measured with labeled microspheres was increased 167% (P less than 0.01) and 58% (P less than 0.04), respectively. Calf muscles of the burned limb, frozen in situ, showed a 48% decrease in ATP (P less than 0.001), 37% decrease in ADP (P less than 0.001), 192% increase in AMP (P less than 0.01), 45% decrease in total adenine nucleotides (P less than 0.001), 132% increase in pyruvate (P less than 0.001), and 377% increase in lactate (P less than 0.001). Blood flow and ATP, ADP, total nucleotides, and pyruvate levels of calf muscles of unburned limb of burned rats did not differ from controls, but AMP and lactate were increased 115% (P less than 0.05) and 144% (P less than 0.001), respectively. The decrease in ATP and increase in AMP and lactate in muscles of the burned limb suggest an increased rate of glycolysis in vivo which may be due, in part, to the stimulation of phosphofructokinase. Furthermore, the increased AMP and lactate may contribute to the increase in blood flow in muscles of the burned limb. It is proposed that thermal injury alters local adenine nucleotide levels, which results in elevated glucose utilization and blood flow in muscles of the burned region.

Adenosine Triphosphate↗
PubMed1980

Depression of the respiratory burst in alveolar and peritoneal macrophages after thermal injury.

The resting O(2) consumption of alveolar and peritoneal macrophages obtained from rats at 4 and 24 h after thermal injury was unaltered from control values. However, when heat-killed Pseudomonas aeruginosa or polystyrene latex particles were added to the cell suspensions to initiate phagocytosis, a significant depression in the respiratory burst accompanying the phagocytic event was demonstrated. The addition of phorbol myristate acetate, used to maximize the respiratory response, was ineffective in elevating, to control values, the respiratory burst of macrophages obtained from burned animals. The deficit was only, in part, serum mediated since the responses could not be restored to control values even when the cells from the burned animals were vigorously washed with control serum and incubated with control serum. The contribution of a burn serum factor, which was non-dialyzable, heat stable at 56 degrees C but not at 65 degrees C, and insensitive to pronase treatment, must be considered. These data indicate that thermal injury results in macrophage metabolic alterations which are mediated, in part, by a burn serum factor. Furthermore, the data suggest that pulmonary alveolar macrophages are more sensitive to thermal injury than peritoneal macrophages. Serum factors contributed, in part, to this observed impairment in the respiratory burst as indicated by: (i) an approximate 50% reversal of the impairment by control serum, and (ii) an approximate decrease of 50 to 80% in the control alveolar macrophage respiratory burst when serum from the thermally injured rats was added to the culture medium.

Animals↗