Acute and postponed action of adriamycin on the contractile function and antioxidant status of the myocardium

Functional, biochemical and morphological studies of rat cardiac muscle after single injection of adriamycin (2.2 mg/kg) were carried out. The myocardium was taken for studies in 2 hours and in 2-3 weeks after adriamycin injection. The isolated heart was perfused retrogradely with Krebs solution and left ventricular isovolumic pressure and perfusion pressure were continuously monitored. Two-fold increase in perfusion rate was accompanied by raised developed pressure, heart rate and perfusion pressure which in the given conditions reflected a tone of coronary vessels. The cardiac contractile function of rats that received adriamycin 2 hours before, remained unaltered as compared to control group, however, perfusion pressure was raised by 26%. These hearts responded to H2O2 introduction (100 microM) into coronary vessels by more profound fall in developed pressure, which fell to 31 +/- 8% after 40 minutes vs. 61 +/- 5% in the control group (p<0.01). In two-three weeks after adriamycin injection, both cardiac contractile function and its responsiveness to oxidative stress induced by H2O2 introduction did not differ from the control, however, perfusion pressure remained elevated and this was accompanied by slowed myocardial relaxation. The myocardial concentration of malonic dialdehyde was moderately increased in adriamycin-treated group in both terms while the activity of antioxidant enzymes (SOD, GPHx and catalase) remained unaltered. Results showed an absence of the direct connection between myocardial antioxidant status and the contractile function changes at adriamycin action.     

Biochemical characterization and purification of a binding protein for 24,25-dihydroxyvitamin D3 from chick intestine.

An earlier study revealed that 24R,25-dihydroxyvitamin D(3) (24R,25(OH)(2)D(3)) inhibits the rapid actions of 1,25(OH)(2)D(3) on stimulation of calcium transport in perfused duodena, as well as activation of protein kinases C and A. In the present work, a specific binding protein (24,25-BP) has been identified and partially characterized. Percoll-gradient resolution of differential centrifugation fractions from mucosal homogenates revealed the highest levels of specific [(3)H]24R,25(OH)(2)D(3) binding to be in lysosomes (approximately eight to tenfold greater than in basal lateral membrane fractions). Incubation of isolated enterocytes with 6.5 nM [(3)H]24R,25(OH)(2)D(3) for 10 s also demonstrated targeting of the steroid to lysosomal fractions. Using freshly isolated lysosomal fractions, time course studies indicated maximal specific binding after a 2-h incubation on ice. Western analyses revealed that the serum transport protein, DBP (vitamin D binding protein), was absent from both lysosomal and basal lateral membrane fractions. Protein dependence studies demonstrated linear binding between 0.05 and 0.155 mg of lysosomal protein. Saturation analyses yielded K(d)=7.4+/- 1.8 nM, B(max)=142+/-16 fmol/mg protein for lysosomes, and K(d)=8.5 nM, B(max)=149+/-25 fmol/mg protein for basal lateral membranes. Hill analyses of lysosomal binding yielded a Hill coefficient of 0.57+/-0.11, indicative of negative cooperativity. Studies with lysosomal proteins revealed a 81%+/-7% competition of 24S,25(OH)(2)D(3) with [(3)H]24R,25(OH)(2)D(3) for binding (P>0.05, relative to competition with 24R,25(OH)(2)D(3)), while 25(OH)D(3) and 1,25(OH)(2)D(3) yielded 53%+/-13% and 39%+/-11% competition respectively (each, P<0.05, relative to competition with 24R,25(OH)(2)D(3)). The apparent affinity of 24S,25(OH)(2)D(3) for 24,25-BP led to testing of the metabolites effectiveness in the perfused duodenal loop system. Vascular perfusion with 130 pM 1,25(OH)(2)D(3) stimulated (45)Ca transport to 2.5-fold above control levels after 40 min, while simultaneous perfusion with 6.5 nM 24S,25(OH)(2)D(3) and 130 pM 1,25(OH)(2)D(3) abolished the stimulatory activity completely. Purification of the 24,25-BP by chromatography revealed a single protein band upon SDS-PAGE and silver staining of 66 kDa. The combined results suggest that 24R,25(OH)(2)D(3) may mediate its hormonal activities through a specific binding protein.     

Adriamycin-induced changes to the myocardial beta-adrenergic system in the rabbit.

The functional integrity of the beta-adrenergic stimulatory pathway in a rabbit model of heart failure induced by long-term adriamycin treatment was investigated. Adriamycin-induced cardiomyopathy was produced in 46 rabbits by injecting 0.75 mg/kg of adriamycin, three times per week, for a period of 11 weeks. Biochemical studies performed on isolated membrane preparations revealed a 40 and 55% decrease in basal adenylyl cyclase activity in the left and right ventricles of the adriamycin treated rabbits, respectively. Furthermore, the Vmax of forskolin stimulation was significantly lower in both ventricles with no change in Kact. The Vmax of 5'-guanylylimidodiphosphate stimulation of the stimulatory guanylyl nucleotide binding protein Gs and beta-adrenergic receptor stimulation by isoproterenol were also significantly decreased (42%) in both ventricles of the adriamycin-treated rabbits with no change in Kact. Despite the decrease in receptor-mediated cyclic AMP production, no decrease in beta-adrenergic receptor population was found. Mechanical studies on the isolated right ventricular papillary muscle revealed a decrease in baseline total tension (3.1 +/- 0.4 g/mm2 to 1.8 +/- 0.2 g/mm2) and dT/dt (15.1 +/- 1.6 g/mm2 s to 7.9 +/- 0.8 g/mm2 s) in the adriamycin-treated rabbits. Furthermore, tension generation and dT/dt response to increasing concentrations of forskolin or isoproterenol were both significantly lower in the adriamycin-treated rabbits as compared to normal. We suggest that a decrease in the activity of the adenylyl cyclase component of the beta-adrenergic stimulatory pathway is largely responsible for the decrease in cyclic AMP generation in the adriamycin-treated rabbits. This defect may play an important role in the decrease of contractility in this model of heart failure.     

Effects of long-term oral treatment with selective vasopressin V2 receptor antagonist (OPC-31260) on adriamycin-induced heart failure in rats

BACKGROUND: In the treatment of heart failure, the effects of therapeutic agents on life prognosis remains unclear. We investigated the effects of long-term oral administration of a nonpeptide, selective, vasopressin V2 receptor antagonist, OPC-31260, on Sprague-Dawley rats that were treated with adriamycin to induce progressive water retention. METHODS: Intraperitoneal saline was administered to 14 rats as a control (Group 1). A total cumulative dose of 15 mg/kg of adriamycin was administered intraperitoneally in six equal doses over a period of 2 weeks to another 52 rats. Adriamycin-treated rats were further divided into Group 2, which received saline (p.o.), and Group 3, which received 50 mg/kg (p.o.) of V2 antagonist. Oral administration continued every day for 6 weeks. Group 1 rats also received saline (p.o.) for 6 weeks. RESULTS: The V2 antagonist decreased urine osmolality and increased diuresis of rats in Group 3. Urinary excretion of electrolytes was not increased by the V2 antagonist in Group 3. Serum osmolality was likewise unchanged by the V2 antagonist in Group 3. Plasma concentrations of vasopressin were significantly higher in Group 3 than in the other groups (Group 1, 4.0+/-1.1 pg/ml; Group 2, 4.2+/-1.5 pg/ml; Group 3, 8.5+/-1.0 pg/ml; p<0.05). During the experimental period, survival rate was higher in Group 3 than in Group 2 (Group 1, 100%; Group 2, 59%; Group 3, 83%). CONCLUSION: Our data show that administration of orally active V2 antagonist did not reduce the survival of adriamycin-treated rats through continuous aquaretic action, despite elevated plasma levels of vasopressin.     

Effects of adriamycin on chronic cardiotoxicity in selenium-deficient rats

Summary Adriamycin (doxorubicin) is an antineoplastic drug used to treat various cancers; however, its chronic use is unfortunately accompanied by cardiotoxicity. This toxicity can be reduced by antioxidant agents such as selenium, and it is particularly interesting that cancer patients are usually deficient in this trace element, which suggests that its supplementation could contribute to beneficial treatment.We have examined the effect of adriamycin on chronic cardiotoxicity in 6-week selenium deficiency in rats. Selenium-deficient rats showed a considerable reduction of selenium levels and of selenium-containing glutathione peroxidase. Cardiac lipid peroxides increased slightly in the deficient rats, whereas plasma and heart lipid peroxides increased markedly in adriamycin-treated rats. This increase was greatly accentuated in selenium deficiency. These results suggest that free radical mechanism may be contributing to adriamycin toxicity, and above all show the importance of balancing the selenium levels in adriamycin-treated subjects to limit its harmful myocardial action. A decrease in adriamycin cardiotoxicity with no concomitant decrease in its antineoplastic activity would be of considerable value by improving the therapeutic benefit of the drug.     

Progressive cardiac dysfunction in adriamycin-induced cardiomyopathy rats

Cardiotoxicity is a limiting factor in the treatment of cancer with adriamycin. We administered adriamycin by a method which minimizes the risk of peritonitis in an adriamycin-induced cardiomyopathy rat model. Sixty male Wistar rats were given 1 mg/kg of adriamycin intraperitoneally 15 times over a 3-week period (total dose, 15 mg/kg) to induce the cardiomyopathy model. Fifteen control rats received 10 ml/kg body wt. saline 15 times over 3 weeks. The animals were observed for 12 weeks and assessed for mortality, and cardiac volume and function was analyzed by echocardiography at 4, 8, and 12 weeks. In rats treated with adriamycin, the cumulative mortality was 35.8% while in the controls, none of the rats died. Left ventricular diameter of the systole (LVDs) was significantly increased at 4 weeks (4.5 vs. 3.3 mm; P<0.001). Left ventricular diameter of the diastole (LVDd) was significantly increased at 12 weeks (7.9 vs. 7.0 mm; P<0.01) and the % fractional shortening (FS) was significantly decreased at 8 weeks (33.4% vs. 50.0%; P<0.01) in the adriamycin-treated rats. This administration method appears to be useful for investigating the cardiac effect of adriamycin while avoiding the influence of peritonitis typically caused by an intraperitoneal injection of higher single doses of adriamycin.     

1,25-Dihydroxyvitamin D3-mediated vesicular transport of calcium in intestine: time-course studies

Previous work has biochemically identified lysosomes containing calcium and calbindin-D28K (CaBP) in chick intestine that are sensitive to 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] status. In the present work, lysosomal accumulation of 45Ca was optimal after 30 min of absorption from in situ ligated duodenal loops. The areas under the curves, defined as lysosomal fractions in Percoll gradients, were calculated, and values after 10, 20, 30, and 40 min of transport were (+D/-D ratio) 0.90, 1.62, 1.88, and 1.78, respectively. Lysosomal CaBP also increased in parallel with the time of absorption and was not due to nonspecific adsorption. When lysosomal 45Ca was determined 2.5, 5, 10, 15, and 43 h after administration of 1.3 nmol 1,25-(OH)2D3 or vehicle, the area ratios were 1.02, 1.47, 3.10, 1.88, and 1.29, respectively. Analyses of serum 45Ca in the same birds yielded a closely parallel time course with 1,25-(OH)2D3-dependent intestinal calcium absorption; values were 108 +/- 12% (+/- SE), 164 +/- 29%, 300 +/- 35%, 340 +/- 39%, and 169 +/- 8% of vitamin D-deficient control values at 2.5, 5, 10, 15, and 43 h, respectively. Immunoreactive CaBP in lysosomal fractions did not change significantly between 5-43 h after administration of seco-steroid. A similar series of experiments was conducted with microsomal membranes containing putative endocytic vesicles, which are believed to deliver calcium to the lysosomes. The brush border origin of the vesicles was supported by the internalization of anti-CaBP immunoglobulin G after 3 min of absorption. Accumulation of 45Ca by endocytic vesicles was subsequently found to be maximal after 20 min of absorption (+D/-D = 1.48), declining again at 30 min (+D/-D = 1.16), while CaBP levels in the same fractions remained unchanged between 0-30 min of absorption. These data together with the lower 45Ca specific activity in pinocytic vesicles relative to lysosomes suggest that lysosomes fuse with several endocytic vesicles in the interval of 20-30 min of absorption. Time-course studies with endocytic vesicles indicated that 1,25-(OH)2D3 stimulated uptake more rapidly than transport; 2.5, 5, 10, 15, and 43 h after seco-steroid administration, +D/-D ratios were 1.32, 1.87, 2.05, 1.72, and 1.36, respectively. CaBP levels in the same vesicle fractions did not correlate well with relative 45Ca content.(ABSTRACT TRUNCATED AT 400 WORDS)     

Hepatic and plasma lysosomal enzyme activity in shock-like state following administration of polysaccharide-protein complex isolated from Candida albicans

Polysaccharide-protein complex (PPC) derived from the cell walls of Candida albicans exerts several pathophysiological effects in laboratory animals similar to the symptoms of shock found at acute disseminated candidiasis. The present study evaluated the presumed fragility of hepatic lysosomes in rats in shock-like state following a single dose of PPC (25 mg/kg) administered intravenously, in terms of temporal changes in lysosomal enzymatic activity (cathepsin D, N-acetylglucosaminidase) in four sedimentable fractions and supernatant of liver homogenate after differential centrifugation, as well as in plasma. A reduction of sedimentable lysosomal activity (13,000 X g) was observed during the first hours (3-5 h) after administration of PPC with both lysosomal hydrolases, accompanied by a concomitant increase in the unsedimentable activity that represented the enzymatic activity released from disrupted lysosomes. Plasma levels of cathepsin D and N-acetylgucosaminidase had the same pattern of changes, reaching the maximum level 2-3 h after administration of PPC with a tendency of returning to the control levels by 12 h. Thus PPC from Candida albicans appears to have similar effects upon integrity of hepatic lysosomes as bacterial endotoxins have by labilizing the lysosomal membrane.     

Thyroid lysosomal enzyme activity and ultrastructure after subtotal thyroidectomy

Subtotal thyroidectomies were performed in rats to increase the level of endogenous TSH, creating a condition of chronic TSH stimulation. The activities of various classes of lysosomal enzymes (cathepsin D, beta-glucuronidase, and aryl sulfatase A) were studied in thyroid tissue remaining in situ at various time intervals after subtotal thyroidectomy (sub-tx). These alterations were correlated with morphometric and ultrastructural changes in tissue lysosomes and with serum T4 and TSH. Specific activities of all three lysosomal enzymes were elevated in the residual tissue as compared with those in control tissue during 7 weeks after sub-tx in the first experiment. In the second experiment, the activities of all three enzymes were elevated both 3 and 6 weeks after sub-tx, and the activities of cathepsin D and aryl sulfatase A in the postnuclear homogenate (S2) were significantly elevated. Plasma TSH was elevated and T4 was decreased both 3 and 6 weeks after sub-tx. The results of the third experiment determined that there were significant alterations in nuclear cytoplasmic ratios as well as in the number, area, and volume density of lysosomes in both groups compared with respective control values. In addition, both lysosomal area and volume density in animals 6 weeks after sub-tx were significantly larger than those in animals 3 weeks after sub-tx. We conclude that chronic stimulation of residual thyroid tissue 6 weeks after sub-tx causes alterations in lysosomal ultrastructure as well as in lysosomal enzyme activity.     

Rescue by coenzyme Q10 from electrocardiographic abnormalities caused by the toxicity of adriamycin in the rat.

The administration of adriamycin to rates increased (P less than 0.01) the interval, measured in msec, of the electrocardiographic QRS traces in rats, and the magnitude of the increase was ca. 50%. The administration of coenzyme Q10 to such adriamycin-treated rats allowed "rescue" or restoration of a normal QRS complex after 7 days of administration of coenzyme Q10. The QRS complex then remained normalized during the subsequent period of 21-30 days, by which time the cumulative dose of adriamycin had reached 24 mg/kg. Also, the QRS interval was lower (P less than 0.01) on day 33 than it was for rats treated to the same day with adriamycin alone. Coenzyme Q10 offers promise of rescue from at least some of the cardiotoxicity occurring in adriamycin-treated cancer patients, probably by a similar mechanism to that of the clinical rescue from toxicity of methotrexate by a cofactor of folic acid (citrovorum factor).     

Subcellular localization of marker enzymes, lipase and triglyceride in rat heart.

Subcellular fractions containing lipase and triglyceride, prepared from rat hearts homogenized in 0.25 m sucrose, were characterized by the use of marker enzymes. In addition to the usual mitochondrial and microsomal pellets, an additional fraction was sedimented between 8000 g × 10 min and 13 000 g × 10 min. Assays for N-acetyl-β-glucosaminidase, β-glucuronidase and cathepsin D indicated that the relative specific activity (R.S.A.) of these enzymes in this fraction was two to three times higher than any of the other subcellular fractions. Since these hydrolytic enzymes are “marker” enzymes for lysosomes in other tissues, the results indicate that it is possible to separate rat heart homogenate into several fractions, one of which has the characteristics of the light mitochondria or lysosomes. Several other hydrolytic enzymes (acid phosphatase, α-glucosidase and β-galactosidase) yielded R.S.A. values which indicated that there was no enrichment of their activity in the lysosomal fraction. The R.S.A. patterns of 5′-nucleotidase and alkaline phosphatase indicated that the plasma membranes (sarcolemma) were sedimenting with the microsomal fraction. This latter fraction exhibited a high R.S.A. of rotenone-insensitive NADH cytochrome-c reductase. Measurement of lipase activity and triglyceride content of the subcellular fractions indicated a relative enrichment of both of these in the lysosomal fraction. Although the R.S.A. of lipase was high in both the lysosomal and microsomal fractions, addition of serum in the assay reduced the R.S.A. of the lipase in the microsomal fraction without altering the high R.S.A. of the lysosomal pellet. Thus, a fraction has been separated from rat heart homogenates with lysosomal characteristics. Associated with this fraction was also an enrichment of triglyceride content and lipase activity, which may be important for turnover of the former in the heart cell.     

Hepatic accumulation of lysosomes and defective transcytotic vesicular pathways in cirrhotic rat liver.

To investigate the potential role of lysosomes in cirrhosis, we analyzed the activity of lysosomal enzymes in rats exposed long-term to phenobarbital and carbon tetrachloride. The activity of lysosomal enzymes was markedly increased in the homogenate of cirrhotic livers (e.g., arylsulfatase 9 +/- S.D.2 vs. 16 +/- 6 nmoles.min-1.mg-1 in control rats and cirrhotic rats, respectively; p less than 0.001). The corresponding plasma levels were also increased (7 +/- 1 vs. 12 +/- 3 nmoles.min-1.mg-1; p less than 0.01), whereas biliary excretion was diminished (16 +/- 7 vs. 7 +/- 2 pmol.min-1.gm liver-1; p less than 0.05) in cirrhotic rats. Stereological quantification of lysosomes visualized cytochemically revealed an increase of pericanalicular lysosomes averaging 1.5 +/- 0.4 around a canaliculus in controls and 3.7 +/- 1.0 in cirrhotic rats (p less than 0.01). Because this suggested a defect in the transcellular vesicular pathway, we investigated the biliary excretion of horseradish peroxidase and epidermal growth factor in perfused livers. Bile flow and total horseradish peroxidase excretion were similar in control rats and cirrhotic rats. However, the early peak of biliary horseradish peroxidase excretion--usually taken as evidence of paracellular transport--was increased in cirrhotic rats (13 +/- 7 vs. 57 +/- 22%; p less than 0.01), whereas the second peak--reflecting the transcellular vesicular pathway(s)--was markedly reduced (87 +/- 7 vs. 43 +/- 22%; p less than 0.001). A similar reduction in the biliary excretion of intact epidermal growth factor and of its degradation products was found. These results demonstrate an increased number of lysosomes in hepatocytes of cirrhotic livers; this appears to be the result of accumulation rather than proliferation, in view of the reduced transcellular vesicular movement of different markers into bile.     

Effect of chloroquine on the form and function of hepatocyte lysosomes. Morphologic modifications and physiologic alterations related to the biliary excretion of lipids and proteins

In these experiments, we tested the hypothesis that chloroquine, a lysosomotropic agent which modifies protein and lipid metabolism by hepatocyte lysosomes, would alter the biliary excretion of lipids and lysosomal enzymes. We treated male rats for 5 days with intraperitoneal chloroquine (50 mg/kg body wt, n = 9) or saline (n = 8) and collected bile for 6 h via bile fistulas; rats were then killed and livers homogenized for biochemical analyses or processed for electron microscopy. Chloroquine markedly increased the biliary excretion of three lysosomal enzymes (mean +/- SEM) expressed as milliunits of activity per gram liver: N-acetyl-beta-glucosaminidase (24.4 +/- 2.7 vs. 12.5 +/- 1.4, p less than 0.01), beta-glucuronidase (26.4 +/- 4.7 vs. 10.9 +/- 1.4, p less than 0.01), and beta-galactosidase (9.8 +/- 1.7 vs. 5.5 +/- 0.8, p less than 0.05). In contrast, biliary outputs of enzymes associated with other organelles (e.g., alkaline phosphodiesterase I and lactic dehydrogenase) were unaffected by chloroquine treatment. Biliary cholesterol secretion was decreased after chloroquine administration (0.28 +/- 0.02 mumol/g liver vs. 0.39 +/- 0.03 mumol/g liver, p less than 0.01), but bile acid and phospholipid secretion were not altered; as a result, cholesterol saturation of bile decreased by 22% (p less than 0.05). Hepatic activities of all three lysosomal enzymes were increased after chloroquine administration (p less than 0.04); activities of enzymes associated with mitochondria, plasma membrane, endoplasmic reticulum, and cell sap were not altered. Morphometric analysis of electron micrographs of rat livers demonstrated a marked increase (p less than 0.001) in the number of lysosomelike vesicles and autophagic vacuoles in the vicinity of bile canaliculi after chloroquine administration; also, the number of canalicular microvilli decreased (p less than 0.003) after chloroquine treatment. We conclude that altered hepatic lysosomal morphology and function after chloroquine is accompanied by marked changes in outputs of lipids and lysosomal enzymes into bile. These findings call attention to a possible role for hepatic lysosomes in modulating biliary protein and lipid secretion.     

Ethanol Administration Alters the Proteolytic Activity of Hepatic Lysosomes

Protein accumulation in liver cells contributes to alcohol-induced hepatomegaly and is the result of an ethanol-elicited deceleration of protein catabolism (Alcohol Clin Exp Res 1349, 1989). Because lysosomes are active in the degradation of most hepatic proteins, the present studies were conducted to determine whether ethanol administration altered the proteolytic activities of partially purified hepatic lysosomes. Rats were fed liquid diets containing either ethanol (36% of calories) or isocaloric maltodextrin for periods of 2–34 days. Prior to death, all animals were injected with [³H]leucine to label hepatic proteins. Rats subjected to even brief periods of ethanol feeding (2–8 days) exhibited significant hepatomegaly and hepatic protein accumulation compared with pair-fed control animals. Crude liver homogenates and isolated lysosomal-mitochondrial and cytosolic subfractions were incubated at 37°C, and the acid-soluble radioactivity generated during incubation was measured as an index of proteolysis. At neutral pH, in vitro protein breakdown in incubated liver homogenates and subcellular fractions from control and ethanol-fed rats did not differ significantly. The extent of protein hydrolysis increased when samples were incubated at pH 5.5, which approximates the pH optimum for catalysis by lysosomal acid proteases. Under the latter conditions, partially purified lysosomes from control animals had 2-fold higher levels of proteolysis than corresponding fractions from ethanol-fed rats. The difference in proteolytic capacity appeared to be related to a lower latency and a higher degree of fragility of lysosomes from ethanol-fed rats at the acidic pH. The results suggest that ethanol-induced alterations in lysosomal membranes may be partially responsible for their altered capacities for protein hydrolysis. Such changes may result from ethanol-related alterations in lipid metabolism that may affect lysosome biogenesis or the maturation of lysosomes from autophagic vacuoles.     

Exercise habits and physical performance during comprehensive rehabilitation after coronary artery bypass surgery.

The effects of training as part of a comprehensive rehabilitation programme on exercise capacity and habits was studied in 171 male coronary artery bypass surgery patients randomized into a rehabilitation (R) (n = 93) and a reference, hospital-based treatment (H), group (n = 78). The rehabilitation programme started with a 2-day informative course before surgery and continued with a 3-week exercise-based course 2 months after surgery followed by a 2-day refresher 8 months post-operatively. The percentages of subjects having regular exercise were 22% and 10% pre-operatively, 42% and 38% 6 months and 46% and 38% 12 months after surgery in the R and H groups, respectively. The changes in the proportions observed in R and H groups were not significantly different. Total work during a bicycle exercise test increased from 38.9 +/- 24.3 kJ pre-operatively to 64.0 +/- 31.4 kJ 6 months (P less than 0.001) and to 70.0 +/- 35.7 kJ 12 months (P less than 0.001) post-operatively in group R and from 40.8 +/- 25.6 kJ to 57.3 +/- 26.6 kJ (P less than 0.001) and to 60.4 +/- 30.8 kJ (P less than 0.001) in group H, respectively. The increase from the pre-operative value was greater in group R than in group H both 6 (P = 0.03) and 12 months (P = 0.02) after surgery. Respective changes occurred in maximal work load, but the increase was significantly greater in group R than in group H only 12 months post-operatively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Role of lysosomes on human ulcerogenic gastropathies. Effect of zinc ion on the lysosomal stability.

Numerous conditions are involved in the equilibrium between protective and aggressive factors for gastric mucosa injuring. Among them the lysosomal membrane stability plays a very important role in the inflammatory process. Zinc ion is a well-known lysosomal membrane stabilizer. When given orally to animals or even to humans it protects gastric mucosa against erosive lesions induced by a variety of experimental conditions. Compared with the control group (8.45 +/- 1.49 mU/mg) the lysosomes isolated from samples of gastric mucosa obtained from patients suffering of erosive gastropathies, showed a great liability on their membranes (18.37 +/- 4.52 mU/mg). When these patients were treated orally with zinc sulfate (100 mg of zinc element, twice a day, for two weeks) the lysosomes isolated from their gastric mucosa showed a strong reduction on enzymatic activity (5.49 +/- 1.02 mU/mg), probably due to increasing on the membrane stability. Based on these experimental findings we propose the use of zinc ion as an important adjuvant in treatment of erosive gastropathies.     

Properties of lysosomes in guinea pig heart: subcellular distribution and in vitro stability.

Some 20 hydrolytic enzymes, known to be of lysosomal origin in rat liver, were assayed in fractions of guinea pig heart. The enzymes included glycosidases, esterases, proteases (cathepsins) and nucleases. All exhibited structure-linked latency and had optimal activity in acid pH, conforming to the biochemical definition of lysosomal enzymes. Six enzymes which had high activity in guinea pig heart were also measured in rat liver using the fractionation and assay methods employed for myocardium. The acid hydrolase activities of the two tissues are compared and discussed in relation to the cellular origins of the organelles with which they are associated.A lysosome-rich suspension was prepared from guinea pig left ventricle by differential centrifugation. The isolated lysosomes were subjected to various labilizing conditions and the rate of lysosome disruption was monitored by measurements of latent acid hydrolase activity. Loss of latent activity was accelerated by heating, hypotonicity, changes in pH and by addition of NaCl and KCl. The kinetics of lysosomal enzyme release were similar for each of the enzymes tested, with the exception of β-glucuronidase which was released more rapidly by heating and less rapidly by hypotonicity.Subcellular distribution profiles of the acid hydrolases in guinea pig heart were obtained by sucrose density gradient centrifugation. Hearts from both normal and Triton WR 1339 treated animals were fractionated. The modal equilibrium densities of the acid hydrolases revealed the presence of five biochemically distinct lysosomal populations in ventricle tissue, three of which were accessible to Triton WR 1339.The findings in this study show that myocardial lysosomes are a heterogeneous group of organelles with different enzymatic constituents and different physical properties. In view of this there is a need for careful choice of representative marker enzymes in studies on the functions of myocardial lysosomes and their role in disease.     

部分液体通气治疗急性肺损伤家兔

目的 观察部分液体通气（ＰＬＶ）对急性肺损伤（ＡＬＩ）家兔肺内气体交换、肺顺应性、体循环功能的影响。方法 健康雄性新西兰兔２４只,用油酸制备成急性肺损伤模型后随机分为３组,每组８只。各组采用不同方法治疗：呼气末正压（ＰＥＥＰ）组,常规机构通气（ＣＭＶ）＋ＰＥＥＰ治疗;生理盐水（ＮＳ）组,肺内注入ＮＳ同时＋ＣＭＶ＋ＰＥＥＰ;ＰＤＣ组,肺内注入全氟碳化合物－全氟萘烷（ＦＤＣ）同时＋ＣＭＶ＋ＰＥＥＰ。分     

Intracellular hormone receptors: evidence for insulin and lactogen receptors in a unique vesicle sedimenting in lysosome fractions of rat liver

Previous studies have established the presence of polypeptide hormone receptors in Golgi fractions from rodent liver. In this study we attempted to identify peptide hormone receptors in other intracellular elements, particularly lysosomes. Tritosomes were prepared by a standard procedure, and highly purified secondary lysosomes were prepared by fractionating the L fraction of rat liver in a discontinuous metrizamide gradient into subfractions L1 to L4. Binding of 125I-labeled insulin and 125I-labeled somatotropin was studied with membranes prepared from osmotically shocked fractions. The L2 and L3 fractions, virtually devoid of galactosyltransferase (UDP galactose:2-acetamido-2-deoxy-D-glucosylglycopeptide galactosyltransferase, EC 2.4.1.38) but highly enriched in acid phosphatase [orthophosphoric-monoester phosphohydrolase (acid optimum), EC 3.1.3.2], appeared as classical secondary lysosomes by electron microscopy. When compared with Golgi fractions, the level of specific binding per 50 micrograms of protein of 125I-labeled somatotropin in L2 and L3 was 1/3, whereas that of 125I-labeled insulin was comparable. L1, which was reduced in acid phosphatase and increased in galactosyltransferase activities, showed higher hormone binding than did L2 and L3. This was not attributable to Golgi fraction contamination, as evident by specific binding/galactosyltransferase ratios. Binding to tritosome membranes could be largely accounted for by variable contamination with Golgi fractions as judged by specific binding/galactosyltransferase ratios. To clarify the distribution of receptor sites in lysosomal preparations, we fractionated the entire L fraction on a continuous Percoll gradient. Acid phosphatase and galactosyltransferase activities were segregated to the high and low density ranges of the gradient, respectively; however, the fractions enriched in hormone binding were of intermediate density, distinct from Golgi and lysosomal biochemical markers. We conclude that intracellular receptors are found not only in galactosyltransferase-containing very low density lipoprotein-marked Golgi vesicles but also in a unique vesicle of intermediate density between classical Golgi and lysosomal structures.