Activity Of Lysosomal Hydrolases Research Articles

Anabolic Androgenic Steroids Abuse and Liver Toxicity

In the athletes the wide use of Anabolic Androgenic Steroids (AAS) cause series damage in various organs, in particular, analyzing the liver, elevation on the levels of liver enzymes, cholestatic jaundice, liver tumors, both benign and malignant, and peliosis hepatis are described. A prolonged AAS administration provokes an increase in the activities of liver lysosomal hydrolases and a decrease in some components of the microsomal drug-metabolizing system and in the activity of the mitochondrial respiratory chain complexes without modifying classical serum indicators of hepatic function. Liver is a key organ actively involved in numerous metabolic and detoxifying functions. As a consequence, it is continuously exposed to high levels of endogenous and exogenous oxidants that are by-products of many biochemical pathways and, in fact, it has been demonstrated that intracellular oxidant production is more active in liver than in tissues, like the increase of inflammatory cytokines, apoptosis and the inhibitors of apoptosis NF- κB and Heat Shock Proteins.

EFFECTS OF STATINES ON ACTIVITY OF LYSOSOMAL HYDROLASES IN ALLOXAN DIABETES

Paper shows that alloxan diabetes in rats increases nonsedimenteted activity of lysosomal hydrolases in liver, myocardium and skeletal muscle, but decreases nonsedimenteted activity of them. Lovastatin and simvastatin cause decreases of expressiveness of these processes in rats with alloxan diabetes

Importance of Phagosomal Functionality for Growth Restriction of Mycobacterium tuberculosis in Primary Human Macrophages

The best characterized survival mechanism of Mycobacterium tuberculosis inside the macrophage is the inhibition of phagosomal maturation. Phagosomal maturation involves several steps including fusion with lysosomes and acidification. However, it has not been elucidated which components of phagosomal maturation correlate with growth restriction of virulent mycobacteria in human macrophages, and we aimed to study this. We infected human monocyte-derived macrophages with M. tuberculosis and assessed bacterial replication, translocation of CD63 to the phagosome, and phagosomal acidification. We found that unstimulated human macrophages were able to control infection with M. tuberculosis upon inoculation at a low multiplicity of infection (MOI) of 1, but not at a high MOI of 10. The low MOI resulted in a macrophage-controlled balance between host cells and bacteria. Both H37Rv and H37Ra infection, at high and low MOI, led to equally ineffective translocation of CD63 to the phagosome. On the other hand, acidification of mycobacterial phagosomes was more efficient at MOI 1 than 10 with both mycobacterial strains, consistent with a direct or indirect role for phagosomal acidification in restricting M. tuberculosis growth. Furthermore, inhibition of the vacuolar H⁺-ATPase as well as of cathepsin D led to enhanced mycobacterial replication inside the macrophage. This again shows the importance of phagosomal acidification for control of mycobacterial growth, through the activation of lysosomal hydrolases. We conclude that acidification and related functional aspects of the mature phagosome are important factors for restriction of M. tuberculosis replication in human macrophages.

Análisis mutacional de GNPTAB para el diagnóstico molecular de mucolipidosis tipo II (I-cell disease). Descripción de dos nuevas mutaciones sin sentido asociadas con la enfermedad

Introduction Mucolipidosis type II alpha/beta (MLII or I-cell disease) (MIM 252500) is a rare inborn lysosomal hydrolase trafficking disorder caused by the deficient activity of N-acetylglucosaminyl 1-phospho (NAcGlc-1-P) transferase, the enzyme responsible for the initial step in the generation of the mannose 6-phosphate recognition marker. NAcGlc-1-P-transferase is a multimeric enzyme composed of 3 polypeptide subunits (α, β and γ) encoded by 2 different genes. The gene encoding for the α/β subunits ( GNPTAB), located on chromosome 12q23.3, is altered in MLII. To date, at least 20 missense/nonsense GNPTAB mutations have been described and incriminated in this autosomal recessive disorder. In this study, we characterized the molecular defect of a new case of MLII, presenting important skeletal abnormalities. Material and methods The activity of lysosomal hydrolases in the patient's fibroblasts, plasma and cell culture medium was determined using appropriate fluorogenic substrates. All exons, as well as exon-intron boundaries, of the GNPTAB gene were sequenced after PCR amplification of the patient's genomic DNA. GNPTAB exon 11 was also studied by enzyme restriction analysis in the whole family. Results In the patient's fibroblasts, a residual activity of lysosomal hydrolases averaging 14% of control values was found, while a 32 and 9-fold increase in the activity of these enzymes was detected in plasma and the fibroblast culture medium, respectively. Two novel nonsense disease-associated GNPTAB mutations, c.1383C > A (p.Cys461X) and c.3410T > A (p.Leu1136X) were identified, the patient being a compound heterozygote. Conclusions Characterization of the GNPTAB molecular defects in a new case of MLII and the identification of two novel nonsense mutations facilitated the prenatal diagnosis of this disease in the patient's family.

Effect of One Year of Cryopreservation on the Activity of Lysosomal Hydrolases from EBV‐Transformed Lymphocytes

Background. The Epstein-Barr virus (EBV) was used as an agent of B lymphocyte proliferation for subsequent diagnosis of lysosomal storage disease. Due to the constant handling of long-preserved samples in our cell bank, we decided to observe the behavior and then compare cultured and frozen samples for at least one year's cryopreservation. Methods. Twenty-five samples from healthy individuals were used to assess the possible changes in activity of enzymes β-galactosidase, β-glucosidase, α-iduronidase, α-galactosidase, and α-glucosidase. Transmission electron microscopy was used to confirm cell transformation of B lymphocytes into EBV-infected cells, generating lymphoblastoid cell lines. Results. Transmission electron microscopy findings confirmed previous reports in the literature that is, significant and evident morphological changes in the nucleus occur after day 12 and the consequent cell transformation into EBV-infected cells. After thawing and subsequent treatment with the five enzymes utilized, we observed no significant changes in samples cryopreserved for more than one year, as compared to samples cultured for 12 days.

Feasibility of using cryopreserved lymphoblastoid cells to diagnose some lysosomal storage diseases

The Epstein-Barr virus (EBV) is utilized as a tool in the study of cellular biology because of its capacity to transform B-lymphocytes. For this reason, EBV is used in conservation of human B-lymphocytes for long periods for subsequent evaluation of lysosomal hydrolase activity. Lymphoblastoid cell lines have several advantages for use over other cell types, such as prompt availability and possibility to develop, characterize and standardize cell banks, to test effects of promising pharmaceutical reagents. The study below presents biochemical data that demonstrate validity of lymphoblastoid cell lines for diagnosis of GM1-gangliosidosis, Gaucher, Fabry and Pompe diseases and mucopolysaccharidosis type I. Cultures were prepared from peripheral blood, collected from 25 normal subjects and 13 affected individuals. Enzyme activities and immunohistochemistry (IHC) were measured. Activities of enzymes beta-galactosidase, beta-glucosidase, alpha-iduronidase, alpha-galactosidase and alpha-glucosidase were measured before and after cryopreservation for 180 days. Enzymatic activity was measured when transformation was confirmed by IHC. We observed some significant alterations in enzymatic activity of non-cultured cells when compared to others that had been cultured for 12 days and kept frozen for 180 days. However, these alterations did not invalidate use of the technology of transformation of lymphoblastoid cell lines with EBV, to diagnose the diseases mentioned above, in view of the fact that the cultured cells, before and after freezing, demonstrated similar enzymatic activities.

The Influence of Estrogen on Skeletal Muscle

As women enter menopause, the concentration of estrogen and other female hormones declines. This hormonal decrease has been associated with a number of negative outcomes, including a greater incidence of injury as well as a delay in recovery from these injuries. Over the past two decades, our understanding of the protective effects of estrogen against various types of injury and disease states has grown immensely. In skeletal muscle, studies with animals have demonstrated that sex and estrogen may potentially influence muscle contractile properties and attenuate indices of post-exercise muscle damage, including the release of creatine kinase into the bloodstream and activity of the intramuscular lysosomal acid hydrolase, beta-glucuronidase. Furthermore, numerous studies have revealed an estrogen-mediated attenuation of infiltration of inflammatory cells such as neutrophils and macrophages into the skeletal muscles of rats following exercise or injury. Estrogen has also been shown to play a significant role in stimulating muscle repair and regenerative processes, including the activation and proliferation of satellite cells. Although the mechanisms by which estrogen exerts its influence upon indices of skeletal muscle damage, inflammation and repair have not been fully elucidated, it is thought that estrogen may potentially exert its protective effects by: (i) acting as an antioxidant, thus limiting oxidative damage; (ii) acting as a membrane stabilizer by intercalating within membrane phospholipids; and (iii) binding to estrogen receptors, thus governing the regulation of a number of downstream genes and molecular targets. In contrast to animal studies, studies with humans have not as clearly delineated an effect of estrogen on muscle contractile function or on indices of post-exercise muscle damage and inflammation. These inconsistencies have been attributed to a number of factors, including age and fitness level of subjects, the type and intensity of exercise protocols, and a focus on sex differences that typically involve factors and hormones in addition to estrogen. In recent years, hormone replacement therapy (HRT) or estrogen combined with exercise have been proposed as potentially therapeutic agents for postmenopausal women, as these agents may potentially limit muscle damage and inflammation and stimulate repair in this population. While the benefits and potential health risks of long-term HRT use have been widely debated, controlled studies using short-term HRT or other estrogen agonists may provide future new and valuable insights into understanding the effects of estrogen on skeletal muscle, and greatly benefit the aging female population. Recent studies with older females have begun to demonstrate their benefits.

Molecular Basis of Chemical Chaperone Effects of N-octyl-b-valienamine on Human b-glucosidase in Low/neutral pH Conditions

Chemical chaperone therapy is a strategy for restoring the activities of mutant lysosomal hydrolases. This therapy involves chemical compounds binding to the dysfunctional enzymes. The chemical chaperones for lysosomal hydrolases are anticipated to stabilize folding of target enzymes by binding at neutral pH and rescuing enzyme activities by dissociation in acidic conditions after transport to lysosome. However, the molecular basis describing the mechanism of action of chemical chaperones has not been analysed sufficiently. Here we present results derived from molecular dynamics simulations showing that the binding free energy between human ?-glucosidase and its known chemical chaperone, N-octyl-?-valienamine (NOV), is lower at pH 7 than at pH 5. This observation is consistent with the hypothetical activity of chemical chaperones. The pH conditions were represented as differences in the protonation states of ionizable residues which were determined from predicted pKa values. The binding free energy change is negatively correlated to the number of hydrogen bonds (H-bonds) formed between GLU235, the acid/base catalyst of the enzyme, and the N atom of NOV. At pH 7, NOV is inserted further into the active site than at pH 5. Consequently, this provides an increase in the number of H-bonds formed. Thus, we conclude that the dissociation of NOV from ?-glucosidase at pH 5 occurs due to an increase in the binding free energy change caused by protonation of several residues which decreases the number of H-bonds formed between NOV and the enzyme.

Effect of anti-inflammatory steroids on the activity of selected lysosomal hydrolases in serum of rats with experimental liver fibrosis.

Liver fibrosis was produced in rats by subcutaneous injections of carbon tetrachloride. The effect of anti-inflammatory steroids (hydrocortisone, prednisone, dexamethasone) on the activity of serum lysosomal hydrolases (beta-N-acetylglucosaminidase, beta-glucosidase and alpha-mannosidase) was investigated in healthy and CCl4 poisoned rats. The marked increase of enzymatic activity in blood serum was observed in animals with CCl4-induced liver fibrosis. Quite opposite results were found in normal rats treated with glucocorticosteroids. In rats which were given both carbon tetrachloride and corticosteroids the obtained values of serum enzymatic activity did not have a uniform character as compared to controls or CCl4 intoxicated rats. Presumable mechanisms of the results obtained are discussed.

Cerebrospinal fluid β-glucocerebrosidase activity is reduced in Dementia with Lewy Bodies

The autophagy–lysosomal degradation pathway plays a role in the onset and progression of neurodegenerative diseases. Clinical and genetic studies indicate that mutations of β-glucocerebrosidase represent genetic risk factors for synucleinopathies, including Parkinson's Disease (PD) and Dementia with Lewy Bodies (DLB). We recently found a decreased activity of lysosomal hydrolases, namely β-glucocerebrosidase, in cerebrospinal fluid of PD patients. We have thus measured the activity of these enzymes – α-mannosidase (EC 3.2.1.24), β-mannosidase (EC 3.2.1.25), β-glucocerebrosidase (EC 3.2.1.45), β-galactosidase (EC 3.2.1.23) and β-hexosaminidase (EC 3.2.1.52) – in cerebrospinal fluid of patients suffering from DLB, Alzheimer's Disease (AD), Fronto-Temporal Dementia (FTD) and controls. Alpha-mannosidase activity showed a marked decrease across all the pathological groups as compared to controls. Conversely, β-glucocerebrosidase activity was selectively reduced in DLB, further suggesting that this enzyme might specifically be impaired in synucleinopathies.

Antilipoperoxidative and membrane stabilizing effect of diosgenin, in experimentally induced myocardial infarction

Altered membrane integrity has been suggested as a major factor in the development of cellular injury during myocardial necrosis. The present study was designed to investigate the effect of diosgenin on lysosomal hydrolases, membrane-bound enzymes, and electrolytes during isoproterenol (ISO)-induced myocardial necrosis in rats. Animals were pretreated with DIOS (80 mg/kg) for a period of 35 days. Myocardial infarction was experimentally induced with ISO (85 mg/kg) twice at 24 h interval. Experimental myocardial infarction was evidenced with marked elevation of creatine kinase-MB (CK-MB) in serum with concomitant increase in lipid peroxidation (plasma thiobarbituric acid reactive substances (TBARS) and hydroperoxides (HP)). Activity of lysosomal hydrolases (beta-glucuronidase, beta-N-acetyl glucosaminidase, beta-D-galactosidase, cathepsin D, and acid phosphatase) was found to be increased in serum and heart tissue of ISO-alone treated animals. DIOS (80 mg/kg) pretreated groups showed significant decrease in CK-MB, lipid peroxidation, and lysosomal hydrolases activity. The membrane-bound enzymes such as Ca2+-ATPase and Mg2+-ATPase activity was increased and Na+/K+-ATPase activity was decreased in the heart tissues of ISO-alone treated animals. These enzyme alterations lead to the change in the electrolytes content such as sodium, potassium, and calcium in the heart tissue. However, DIOS (80 mg/kg) pretreatment reversed the membrane-bound enzymes activity and thereby maintained the normal electrolyte concentration. These results suggest the protective action of diosgenin in ISO-induced myocardial infarction. The salubrious effect observed in this study might be due to the antioxidant and membrane stabilizing potential of diosgenin.

CARDIOPROTECTIVE EFFECT OF FISH OIL ON ISOPROTERENOL‐INDUCED MYOCARDIAL INFARCTION IN RATS

ABSTRACT Epidemiological studies indicate a low incidence of cardiac diseases in populations that consume large amounts of seafood. This effect is attributed to the presence of n‐3 polyunsaturated fatty acids in fish oil. In this study, the protective effect of fish oil against isoproterenol induced changes in histopathology; hematology and lysosomal membrane integrity were evaluated in male wistar rats. The rats were fed fish oil for 45 days prior to isoproterenol treatment. The animals were sacrificed by cervical decapitation method 12 h after the second injection of isoproterenol hydrochloride. The results suggest that pretreatment with fish oil prevented isoproterenol‐induced hematological changes. Lysosomal membrane integrity was also protected in fish oil pretreated rats, as indicated by significantly lowered activities of lysosomal hydrolases in serum and concomitant increase in their activity in the lysosomal fraction of heart. The histopathology studies further confirmed the cardioprotective effect of fish oil. PRACTICAL APPLICATIONSFish oil consumption offers cardioprotection by its ability to modulate biological membranes. This study demonstrates the ability of fish oil to modulate hematological parameters and maintain lysosomal membrane integrity, thereby offering multifaceted protection to the heart. Hence, fish oils, especially those of marine origin, have excellent potential as cardioprotective agents.

Alterations in the Activity of Certain Serum Lysosomal Hydrolases in Patients with Elevated Prostate-Specific Antigen Level Can Help in Distinguishing between Benign and Malignant Prostate Lesions

The aim of this study was to estimate the activity of some lysosomal hydrolases in patients with an elevated prostate-specific antigen level. The activities of prostate-specific antigen, arylsuphatase, acid phosphatase, cathepsin D and α1-antitrypsin were assayed in blood serum. The highest aryl-suphatase and acid phosphatase activity and lowest cathepsin D activity were observed in men with benign prostatic hyperplasia and concomitant asymptomatic inflammation. The lowest arylsuphatase and acid phosphatase activities were revealed in prostate cancer patients, while the highest cathepsin D activity was found in patients with only benign prostatic hyperplasia. We hope that the estimation of aryl-suphatase and acid phosphatase activity may help in distinguishing between benign and malignant lesions.

Protective effect of lupeol and lupeol linoleate in hypercholesterolemia associated renal damage

The association between hypercholesterolemia and kidney damage has been well known for last few decades. The oxidative stress and inflammatory responses are involved in renal injury, which is upregulated in hypercholesterolemic condition. The present study is aimed to evaluate the possible effect of lupeol and its ester derivative, lupeol linoleate in renal damage associated with hypercholesterolemic rats. Hypercholesterolemia was induced in male Wistar rats by feeding them with a high cholesterol diet (HCD) comprising normal rat chow supplemented with 4% cholesterol and 1% cholic acid for 30 days. Lupeol and lupeol linoleate were supplemented (50 mg/kg body wt/day) to HCD fed rats during the last 15 days. Increased levels of renal total cholesterol, triglycerides and phospholipids, along with altered serum biochemical parameters of tissue injury indices and elevated activities of renal marker enzymes (lactate dehydrogenase and alkaline phosphatase) were noted in HCD fed rats. Elevated lipid peroxidation levels coupled with decreased antioxidant status (enzymatic and non enzymatic antioxidants) were observed in hypercholesterolemic rats, which indicate the onset of oxidative changes in the renal tissue. Renal lysosomal acid hydrolase activities (ACP, beta-Glu, beta-Gal, NAG and Cat-D) and acute phase proteins like C-Reactive protein and fibrinogen were significantly increased in HCD fed rats, which further indicates the heightening of inflammation. In addition, histopathological findings also confirmed the renal damage in hypercholesterolemic condition. Lupeol and lupeol linoleate effectively reverted the above abnormalities and was comparable with that of the control. These observations highlight the protective effect of lupeol and its ester derivative in ameliorating the renal injury associated with hypercholesterolemia.

Ameliorative prospective of alpha-mangostin, a xanthone derivative from Garcinia mangostana against β-adrenergic cathecolamine-induced myocardial toxicity and anomalous cardiac TNF- α and COX-2 expressions in rats

Altered membrane integrity and inflammation play a key role in cardiovascular damage. We investigated the salubrious effect of exogenously administered alpha-mangostin against β-adrenergic cathecolamine-induced cardiovascular toxicity with special reference to membrane ATPases, lysosomal hydrolases and inflammatory mediators TNF- α and Cyclooxygenase-2 (COX-2) expressions in albino rats. Induction of rats with isoproterenol (150 mg/kg body wt, i.p.) for 2 days resulted in a significant increase in the activities of serum and cardiac lysosomal hydrolases ( β- d-glucuronidase, β- d-galactosidase, β- d- N-acetylglucosaminidase, acid phosphatase and cathepsin-D). A significant increase in cardiac levels of sodium, calcium with a decrease in the level of potassium paralleled by abnormal activities of membrane-bound phosphatases (Na +–K + ATPase, Ca 2+ ATPase and Mg 2+ ATPase) were observed in the heart of ISO-administered rats. Cardiac TNF- α and COX-2 expressions were assessed by Western blotting. Cardiac TNF- α and COX-2 expressions were significantly elevated in ISO-intoxicated rats. Pre-co-treatment with alpha-mangostin (200 mg/kg body wt.) orally for 8 days significantly attenuated these abnormalities and restored the levels to near normalcy when compared to ISO intoxicated group of rats. In conclusion, alpha-mangostin preserves the myocardial membrane integrity and extenuates anomalous TNF- α and COX-2 expressions by mitigating ISO-induced oxidative stress and cellular damage effectively. Restoration of cellular normalcy accredits the cytoprotective role of alpha-mangostin.

Lysosomes and Fas-mediated liver cell death

A number of studies, mostly performed ex vivo, suggest that lysosomes are involved in apoptosis as a result of a release of their cathepsins into the cytosol. These enzymes could then contribute to the permeabilization of the outer mitochondrial membrane; they could also activate effector caspases. The present study aims at testing whether the membrane of liver lysosomes is disrupted during Fas-mediated cell death of hepatocytes in vivo, a process implicated in several liver pathologies. Apoptosis was induced by injecting mice with aFas (anti-Fas antibody). The state of lysosomes was assessed by determining the proportion of lysosomal enzymes (beta-galactosidase, beta-glucuronidase, cathepsin C and cathepsin B) present in homogenate supernatants, devoid of intact lysosomes, and by analysing the behaviour in differential and isopycnic centrifugation of beta-galactosidase. Apoptosis was monitored by measuring caspase 3 activity (DEVDase) and the release of sulfite cytochrome c reductase, an enzyme located in the mitochondrial intermembrane space. Results show that an injection of 10 microg of aFas causes a rapid and large increase in DEVDase activity and in unsedimentable sulfite cytochrome c reductase. This modifies neither the proportion of unsedimentable lysosomal enzyme in the homogenates nor the behaviour of lysosomes in centrifugation. Experiments performed with a lower dose of aFas (5 microg) indicate that unsedimentable lysosomal hydrolase activity increases in the homogenate after injection but with a marked delay with respect to the increase in DEVDase activity and in unsedimentable sulfite cytochrome c reductase. Comparative experiments ex vivo performed with Jurkat cells show an increase in unsedimentable lysosomal hydrolases, but much later than caspase 3 activation, and a release of dipeptidyl peptidase III and DEVDase into culture medium. It is proposed that the weakening of lysosomes observed after aFas treatment in vivo and ex vivo results from a necrotic process that takes place late after initiation of apoptosis.

Effect of dl-α-lipoic acid on cyclophosphamide induced lysosomal changes in oxidative cardiotoxicity

Cyclophosphamide (CP), one of the widely prescribed antineoplastic drugs can cause fatal cardiotoxicity. The present study is aimed at evaluating the cardioprotective role of lipoic acid in CP induced toxicity. Male albino rats of Wistar strain were divided into four groups and treated as follows: Group I served as control, Group II received a single dose of CP (200 mg/kg b.wt., i.p.), Group III received lipoic acid (25 mg/kg b.wt., orally) for 10 days, and Group IV received CP immediately followed by lipoic acid for 10 days. In CP administered rats, the levels of protein carbonyl and 8-hydroxy-2-deoxyguanosine were increased significantly ( P < 0.001) indicating oxidative changes in the heart tissue. The activities of lysosomal acid hydrolases, β-Glu, β-Gal, NAG, Cat-D and ACP increased significantly ( P < 0.001) in the serum as well as in the heart tissue after CP administration. An increase in hydroxyproline was observed in CP induced rats. Lipoic acid effectively reverted these abnormal biochemical changes to near normalcy. These observations highlight the protective role of lipoic acid in CP induced cardiotoxicity.

Comparison of the measurement of lysosomal hydrolase activity in mycoplasma-contaminated and non-contaminated human fibroblast cultures treated with mycoplasma removal agent

Objectives: To investigate the effect of both mycoplasma contamination and of its remover (MRA), through human fibroblasts culture over the activity of some lysosomal hydrolases. Design and methods: Activity was measured in contaminated fibroblasts before and after the addition of MRA. Results were compared with the enzymatic activity in control fibroblasts with and without MRA. Results: Only β-glucosidase showed no significant alteration in the presence of either mycoplasma or MRA. Total hexosaminidase and β-galactosidase underwent significant interference in the presence of the mycoplasma and the MRA. The % of hexosaminidase A and arylsulphatase A altered their activity only in the presence of MRA. β-Glucuronidase changed its activity only in the presence of mycoplasma. Conclusions: The fibroblast enzymes behaved differently in the presence of MRA and/or mycoplasma, demonstrating the sensitivity of these hydrolases. Our work suggests that mycoplasma and MRA alter the activity of some lysosomal hydrolases.

Mitochondrial Aberrations in Mucolipidosis Type IV

Mucolipidosis type IV is a genetic lysosomal storage disease associated with degenerative processes in the brain, eye, and other tissues. Mucolipidosis type IV results from mutations in the gene MCOLN1, which codes for the TRP family ion channel, mucolipin 1. The connection between lysosomal dysfunction and degenerative processes in mucolipidosis type IV is unclear. Here we report that mucolipidosis type IV and several unrelated lysosomal storage diseases are associated with significant mitochondrial fragmentation and decreased mitochondrial Ca2+ buffering efficiency. The mitochondrial alterations observed in these lysosomal storage diseases are reproduced in control cells by treatment with lysosomal inhibitors and with the autophagy inhibitor 3-methyladenine. This suggests that inefficient autophagolysosomal recycling of mitochondria generates fragmented, effete mitochondria in mucolipidosis. Mitochondria accumulate that cannot properly buffer calcium fluxes in the cell. A decrease in mitochondrial Ca2+ buffering capacity in cells affected by these lysosomal storage diseases is associated with increased sensitivity to apoptosis induced by Ca2+-mobilizing agonists and executed via a caspase-8-dependent pathway. Deficient Ca2+ homeostasis may represent a common mechanism of degenerative cell death in several lysosomal storage diseases.

Preventive effect of naringin on cardiac markers, electrocardiographic patterns and lysosomal hydrolases in normal and isoproterenol-induced myocardial infarction in Wistar rats

Diets rich in natural antioxidants are associated with reduced risk of heart diseases. This study was aimed to evaluate the preventive role of naringin on cardiac troponin T (cTnT), lactate dehydrogenase (LDH)-isoenzyme, cardiac marker enzymes, electrocardiographic (ECG)-patterns and lysosomal enzymes in isoproterenol (ISO)-induced myocardial infarction (MI) in male Wistar rats. Rats subcutaneously injected with ISO (85 mg/kg) at an interval of 24 h for 2 days showed a significant increase in the levels of cTnT, intensity of the bands of LDH-isoenzyme (LDH1 and LDH2) and the activities of cardiac marker enzymes such as creatine kinase-MB (CK-MB), creatine kinase (CK), LDH, aspartate transaminase (AST) and alanine transaminase (ALT) in serum with subsequent decrease in the activities of CK, LDH, AST and ALT in the heart and alterations in ECG-patterns. The activities of lysosomal enzymes (β-glucuronidase, β- N-acetyl glucosaminidase, β-galactosidase, cathepsin-B and cathepsin-D) were increased significantly in serum and the heart of ISO-induced rats, but the activities of β-glucuronidase and cathepsin-D were decreased significantly in the lysosomal fraction of the heart. Pretreatment with naringin (10, 20 or 40 mg/kg) daily for a period of 56 days positively altered the levels of cTnT, intensity of the bands of the LDH1 and LDH2-isoenzyme and the activities of cardiac marker enzymes, ECG-patterns and lysosomal hydrolases in ISO-induced rats. Thus, naringin possess cardioprotective effect in ISO-induced MI in rats.