Beta-glucuronidase activity in human T and B lymphocytes and the Tmu and T gamma subpopulations

The beta-glucuronidase staining characteristics of isolated T cell populations and the Tmu and T gamma enriched fractions derived of them were studied. T gamma lymphocytes were obtained from purified T lymphocytes by ox-IgG rosette sedimentation. The rosette-forming cells in the pellet were referred to as T gamma lymphocytes, whereas the lymphocytes in the interface were referred to as T gamma depleted or Tmu lymphocytes. B cells were studied on rosetted mononuclear cells with either mouse erythrocytes or with Staphylococcus Aureus (Cowan I) bacteria, after a preceeding polyvalent anti-human Ig treatment of the cells. While B cells showed mostly no reactivity, Tmu and T gamma cells were respectively characterised by a "dot-like" and "granular" pattern of reactivity. These findings are in agreement with those observed by others after alpha-naphthyl-acetate esterase or acid phosphatase staining. Within the T lymphocyte fraction, the T non-mu, non-gamma lymphocytes seemed to have a granular pattern of reactivity. The same staining pattern was found in non-B, non-T lymphocytes.

Determination of p-nitrophenol in serum and urine by enzymatic and non-enzymatic conjugate hydrolysis and HPLC. Application after parathion intoxication

In connection with the toxicologic analysis of a number of parathion intoxications a method for determination of free and conjugated forms of p-nitrophenol (p-NP) as the main metabolite of parathion in blood and urine was established. Quantification of conjugates is based on their hydrolysis followed by detection of p-NP using a sensitive HPLC method. Hydrolysis of both p-NP-glucuronide and p-NP-sulfate is performed by specific enzymes and also by mineral acid, the latter is also found to be highly selective under definite conditions. The two hydrolysis methods applied showed a good correlation. The levels of free and conjugated p-NP in series of blood and urine samples were established after survival from two parathion intoxications. The individual levels of p-NP-sulfate and p-NP-glucuronide in both cases are discussed in respect of results made by other authors in this field.

Erythrocyte membrane-bound enzymes in Mastomys natalensis during Plasmodium berghei infection

The pattern of activity of certain membrane-associated enzymes was followed in the erythrocytes of Plasmodium berghei-infected Mastomys natalensis. Parasitized erythrocytes were separated from non-parasitized populations by percoll-density gradient centrifugation. The activity of adenylate cyclase was markedly increased while those of ATPase, acid phosphatase, beta-glucuronidase and N-acetyl-beta-D-glucosaminidase were considerably decreased in the membrane preparations of parasitized erythrocytes as compared to normal erythrocytes. There was a decrease in the activity of ATPase and an increase of adenylate cyclase in the membrane preparations of non-parasitized erythrocytes. However, other enzymes did not alter to a significant extent in non-parasitized erythrocytes. Chloroquine (in vitro) stimulated adenylate cyclase, Na+, K+-ATPase and Ca++Mg++-ATPase while acetylcholinesterase was significantly inhibited.

Cation gradient dependence of the steps in thrombin stimulation of human platelets

Thrombin causes a dose-dependent depolarization of the transmembrane potential of normal human platelets which can be continuously measured by the fluorescent probe, 3,3'-dipropylthiodicarbocyanine, whose distribution across the plasma membrane has been shown to be dependent upon the membrane potential. The dose-dependent depolarization of the platelet's negative membrane potential by thrombin is in large part due to a rapid uptake of sodium. Both the membrane potential change and the rapid sodium influx can be inhibited by a fast acting analog of amiloride, a sodium channel blocker, while valinomycin, a potassium ionophore, has no effect on the potential change nor on the sodium uptake, suggesting that the transmembrane potassium gradient is not important in the thrombin-induced depolarization. Neither the secretion of serotonin nor that of lysosomal enzymes nor the secondary release of the fluorescent probe which correlates with the lysosomal enzyme secretion occur if treatment with valinomycin precedes activation by thrombin. It is thus apparent that: 1) the change in the membrane potential induced by thrombin is directly dependent upon the transmembrane sodium gradient and is primarily due to a dose-dependent sodium uptake by the platelets; and 2) the thrombin-induced secretory processes are dependent upon maintenance of the transmembrane potassium gradients.

Increased serum glycosidase activity in human hypertension

Compared to values obtained in healthy normotensive control subjects, the serum activity of the lysosomal enzymes N-acetyl-beta-D-glucosaminidase (NAG) and beta-glucuronidase, was found to be elevated in patients with mild or borderline hypertension. The serum activity of the cytosolic enzyme lactate dehydrogenase was the same in the two groups. Serum NAG activity in hypertension was inversely correlated with glomerular filtration rate and renal plasma flow. Because of the greater variability of beta-glucuronidase activity, there were no such correlations between the serum levels of this enzyme and the measurements of renal function.

Activity of lysosomal hydrolases in plasma at term and post partum

The activity and isoenzyme pattern in plasma of beta-hexosaminidase (abbreviated Hex) and four other lysosomal hydrolases (alpha-fucosidase, beta-glucuronidase, alpha-hexosaminidase, alpha-mannosidase) were studied in 50 women at term and in 10 women at various intervals during the first 6 days after parturition. All hydrolases had elevated activity at term, compared with controls. After parturition the activity of alpha-mannosidase returned to the normal level within 2 days and that of Hex, beta-glucuronidase, and alpha-hexosaminidase within 6 days; alpha-fucosidase having a slightly elevated activity even at the end of this period. Isoenzyme analysis by isoelectric focusing was informative only in the case of Hex. Thus, the increased activity of Hex at term was mainly due to an increase in the isoenzyme form(s), with pI(s) between 5.6 and 6.8. The enzyme pattern of Hex during pregnancy and post partum observed in this study seems to have certain similarities to the previously noted enzyme pattern of Hex in acute ethanol intoxication and following withdrawal of ethanol. As lysosomal membranes are labilized by elevated levels of steroids, it is of interest to note that high levels of these hormones are found in plasma both at term and in chronic liver disease.

Degranulation and enzyme release during phagocytosis of inert particles and of bacteria by polymorphonuclear neutrophil granulocytes

The degranulation and release of lysosomal (myeloperoxidase, beta-glucuronidase, lysozyme) and cytoplasmic (lactate dehydrogenase-LDH) enzymes from polymorphonuclear neutrophil granulocytes (PMG) during phagocytosis of inert latex particles or bacteria were studied. Degranulation was much faster and more pronounced by phagocytosis of bacteria than of inert particles. A high frequency of lysosome-lysosome as well as lysosome-phagosome fusions suggested that granular material was transported by lysosome- lysosome- phagosome fusions. During bacterial phagocytosis there was evidence of release of granular material into cytoplasm causing enzymatic disintegration. After 60 minutes cell lysis occurred in about 5 per cent of the cells during bacterial phagocytosis. There was non-specific release of LDH during phagocytosis of inert particles, probably due to erythro-phagocytosis. After 60 minutes the release during bacterial phagocytosis amounted to 20-30 per cent of the enzyme content of the cells. A nearly equal release of lysosomal and cytoplasmic enzymes gave support for the idea that cell lysis was the main mechanism of enzyme release.

Lipid peroxidation in rat adjuvant arthritis and its inhibition by indomethacin

Adjuvant arthritis was induced in rats by the injection of Mycobacterium tuberculosis, and its severity was scored according to the macroscopic findings of the legs, tails, and ears. The average score so obtained was lower when the rats also received indomethacin (1.5 mg/kg/day). The depression of the albumin/globulin ratio was inhibited significantly by the administration of indomethacin. The levels of acid phosphatase and beta-glucuronidase were elevated after the injection of an adjuvant, but they decreased to some extent in rats administered indomethacin. The levels of thiobarbituric acid (TBA)-reactive substances in the sera and synovia were elevated at 2 weeks after the injection of adjuvant and decreased thereafter. In rats administered 1.5 mg/kg of indomethacin, the increase in both serum and synovial levels of TBA reactants was inhibited significantly. These observations suggest that the aggravation of adjuvant arthritis may be associated with lipid peroxidation and that indomethacin may, in part, exert its anti-inflammatory effect by preventing lipid peroxide-induced damage of the synovial membrane.

Effect of occupational mercury exposure on plasma lysosomal hydrolases

The activities of three plasma lysosomal hydrolases, beta-galactosidase, beta-glucuronidase and beta-N-acetylglucosaminidase, were studied in 20 workers exposed to metallic mercury vapor in a chlorine alkali plant and in 10 nonexposed referents. The urinary excretion and blood levels of mercury were determined on the day of study, and the history of mercury exposure was reviewed from the records of mercury concentrations in urine and blood over periods of up to 133 months. The average levels of beta-N-acetylglucosaminidase and beta-glucuronidase were higher in the plasma of exposed workers, but the difference was not significant. No significant positive correlation was seen between lyosomal enzyme activities and cumulative long-term exposure to mercury. It is concluded that measurement of plasma lysosomal hydrolase-activities is not of great value in the biological monitoring of workers exposed to low concentrations of metallic mercury vapor. In line with published data, the concentration of mercury showed a clear-cut diurnal variation in nonexposed persons, persons currently exposed and persons with a history of past exposure. The excretion rate of mercury remained constant throughout the day.

Metabolic requirements for maintenance of the chlortetracycline-labeled pool of membrane-bound calcium in human neutrophils

Human neutrophils labeled with chlortetracycline (CTC), commonly used as a probe of membrane-bound calcium, release lysosomal enzymes and exhibit a rapid decrease in fluorescence when exposed to the chemotactic peptide fMet-Leu-Phe or the lectin Con A. This decrease has been attributed to the release of calcium from a membrane-associated "trigger pool." The nature of this putative pool has been further characterized by examining the effects of various inhibitors on the CTC fluorescence response and lysosomal enzyme release from stimulated neutrophils. These agents included inhibitors of glycolysis (2-deoxyglucose and iodoacetate), an uncoupler of oxidative- phosphorylation (KCN), and a sulfhydryl inhibitor (N-ethylmaleimide). Resting neutrophils labelled with CTC demonstrated an enhanced decay of baseline fluorescence when exposed to 2-deoxyglucose or iodoacetate. This suggested that the pool of membrane-bound calcium labelled by this probe was maintained by glycolytic metabolism. Furthermore, 2-deoxyglucose and iodoacetate inhibited both the stimulated decrease in CTC fluorescence and lysosomal enzyme release induced by fMet-Leu-Phe and Con A in a time-dependent manner. KCN did not inhibit either response to stimulation, but did retard the recovery of CTC fluorescence observed when fMet-Leu-Phe was used as the stimulus. High concentrations of N-ethylmaleimide (100 microM) completely inhibited both the CTC fluorescence response and lysosomal enzyme release almost immediately; low concentrations of N-ethylmaleimide (30 microM) inhibited lysosomal enzyme release in a time-dependent manner without significantly affecting changes in CTC fluorescence. These results are consistent with the hypothesis that CTC serves as a probe of membrane-bound "trigger" calcium, the release of which is dependent upon intact glycolysis and is a requirement for lysosomal enzyme release.

The comparative responses of human polymorphonuclear leukocytes obtained by counterflow centrifugal elutriation and Ficoll-Hypaque density centrifugation. I. Resting volume, stimulus-induced superoxide production, and primary and specific granule release

Standard isolation techniques for the human polymorphonuclear leukocyte (PMN) involve sequential exposure of cells to the nonphysiologic environments of dextran, Ficoll-Hypaque (FH) gradient centrifugation, and hypotonic conditions. It has been suggested that these may be harmful to the recovered PMN. Counterflow centrifugal elutriation (CCE) allows separation of human PMNs while the cells are continuously bathed in a physiologic and isotonic buffer. To investigate whether preparative technique may alter PMN activation, we compared PMNs obtained by these two methods for stimulus-induced superoxide production and release of primary and specific granule contents. Resting PMN volume was also evaluated. We observed that PMNs obtained using the CCE method were larger and released significantly more superoxide and specific granule contents than PMNs obtained by the standard FH technique. The possible origins for these differences are discussed.

Ionophore monensin induces Na+-dependent secretion from rabbit neutrophils. requirement for intracellular Ca2+ stores

Rabbit (and human) neutrophils release the secretory enzyme beta-glucuronidase when treated with the ionophore monensin in the presence of Na+. Release of beta-glucuronidase occurs without loss of the cytosol enzyme lactate dehydrogenase and a number of other features of the release process lead us to conclude that a normal exocytotic mechanism is involved. These include sensitivity to metabolic inhibition, enhancement of release induced by cytochalasin B and a requirement for internal sources of Ca2+ when the cells are stimulated with monensin in the absence of extracellular Ca2+. The release process due to monensin differs from that due to receptor directed agonists such as fMet-Leu-Phe and the Ca2+ ionophores A23187 and ionomycin in respect of a prolonged time-course which extends over 20 min; nor do monensin-stimulated neutrophils generate the superoxide anion. The results are discussed in the light of reports which indicate a rôle for Na+ in the activation of neutrophils by other ligands.

Intracellular or extracellular calcium can be used to trigger C5a-stimulated enzyme secretion from rabbit neutrophils

The ability of C5a to stimulate lysosomal enzyme release and 45Ca2+ efflux from rabbit neutrophils was studied. C5a stimulated beta-glucuronidase release from cytochalasin B-treated neutrophils either in the presence or absence of extracellular calcium. Depletion of cell calcium by pretreatment with the calcium ionophore A23187 blocked both the ability of C5a to elicit enzyme release in the absence of extracellular calcium and its ability to stimulate 45Ca2+ efflux. Both actions were dose-dependent over the same concentration range (10(-8)-10(-6) M ionophore A23187). In contrast, ionophore pretreatment had no effect on C5a-stimulated enzyme release in the presence of extracellular calcium. These results suggest that (a) release of cell calcium is required for enzyme secretion in the absence of extracellular calcium, and (b) C5a can trigger near-maximal enzyme release by using calcium from either of two sources: the extracellular space or an intracellular site.

The effect of TEPC-183 plasmacytoma growth on beta-glucuronidase activity in serum and tissues of tumor-bearing mice

beta-Glucuronidase activity increased in the serum of BALB/c mice during the growth of the IgM-secreting plasmacytoma, TEPC-183. The increase appeared to correlate with tumor burden. The beta-glucuronidase activity in tissue homogenates of spleen, liver, and kidney from tumor-bearing mice also increased significantly compared to the levels found in corresponding tissues from normal control mice. Assays of lysosomal and microsomal fractions from livers of TEPC-bearing mice indicated that approximately 70% of the enzyme activity was associated with the lysosomal fraction and the remainder with the microsomal fraction. A similar distribution was found in homogenates prepared from the plasmacytoma itself. In contrast to this the beta-glucuronidase activity in livers from normal BALB/c mice is nearly equally distributed between lysosomal and microsomal fractions.

Possible role of arachidonic acid and of phospholipase A2 in the control of lysosomal enzyme release from human polymorphonuclear leukocytes

We have studied the role of arachidonic acid (AA) metabolism in the release of lysosomal enzymes (beta-glucuronidase and lysozyme) from human polymorphonuclear leukocytes (PMNs). 5,8,11,14-Eicosatetraenoic acid (ETYA), which inhibits both the cyclo-oxygenase and the lipoxygenase pathways of AA metabolism, was found to cause a dose-dependent inhibition of lysosomal enzyme release from human PMNs induced by immunological (i.e., serum-treated zymosan: Zx) and nonimmunological stimuli (i.e., formyl methionine-containing peptide and the Ca2+ ionophore A23187). In contrast, the non-steroidal anti-inflammatory drugs (indomethacin, meclofenamic acid and aspirin), which only block the cyclo-oxygenase pathway of AA metabolism, had little effect on enzyme release from PMNs induced by the same stimuli. 5,8,11-Eicosatriynoic acid (ETI), a selective inhibitor of the lipoxygenase pathway of AA metabolism, caused a dose-dependent inhibition of lysosomal enzyme release elicited by Zx, f-met peptide, and A23187. p-Bromophenacyl bromide (BPB), which inhibits the phospholipase A2 (PLA2) activity in several tissues, was found to cause a dose-dependent inhibition of lysosomal enzyme release induced by the same immunological and non-immunological stimuli. The inhibitory effect of BPB on enzyme release was irreversible and extremely rapid. It appears that activation of PLA2 and the products of the AA metabolism, generated via a lipoxygenase pathway, play an essential role in the biochemical control of human PMNs activation and secretion.

Shock lung--experimental studies on a haemorrhagic hypovolaemic rabbit model

An experimental model of haemorrhagic hypotension was standardized using rabbits to investigate the shock lung syndrome over a period of 120 minutes. Acute hypovolaemia was induced by withdrawal of blood under anaesthesia to a mean arterial pressure of 30 +/- 5 mmHg within 10 minutes. The mean leucocyte counts and the release of lysosomal enzymes (acid phosphatase and beta-glucuronidase) in the blood and in lung tissue, as well as the metabolic capacities of lung tissue in terms of protein and lipid biosynthesis, were investigated at set intervals after 30, 60, 90 and 120 minutes. The results indicate a progressive decline in leucocyte numbers over 120 minutes to about 40% of the original. An immediate granulocytopenia was observed with a relative lymphocytosis within 30 minutes. The beta-glucuronidase and acid phosphatase contents of the plasma increased with time; beta-glucuronidase activity increased progressively as leucocytes disappeared from the circulation. Concomitantly, the capacity of the lung tissue to synthesize protein and lipids was retarded with time, becoming significantly lower than baseline values after 60 minutes of hypovolaemia. The decline in leucocyte numbers in the circulation correlated well with the increase in beta-glucuronidase activity and the retarded metabolic capacity of the lung tissue.

FMLP-induced enzyme release from neutrophils: a role for intracellular calcium

The ability of the chemotactic peptide N-formylmethionyl-leucyl-phenylalanine (FMLP) to stimulate beta-glucuronidase release and 45Ca2+ release from rabbit neutrophils was studied. FMLP stimulated enzyme release from cytochalasin B-treated cells either in the presence or the absence of extracellular calcium. Depletion of cell calcium, by exposure to either ethyleneglycol-bis(beta-aminoethylether)-N,N'-tetraacetic acid or the calcium ionophore A23187, blocked the ability of FMLP to stimulate enzyme release and 45Ca2+ release in the absence of extracellular calcium. The ability of A23187 to lower the 45Ca2+ content of neutrophils, to block FMLP-stimulated 45Ca2+ release, and to inhibit FMLP-stimulated enzyme release in the absence of calcium was dose dependent over the same concentration range (10(-8) to 10(-6) M A23187) for all three actions. In contrast, FMLP stimulated enzyme release from A23187-treated cells, provided that extracellular calcium was present. This secretory response was normal as judged by cell ultrastructure and FMLP dose-response relationships. It is concluded that A23187 depletes a pool of intracellular calcium usually released by FMLP and that release of calcium from this pool is necessary for initiation of enzyme secretion in the absence of extracellular calcium.

Changes of the activity of acid phosphatase and beta-glucuronidase in isolated platelets of whole-body irradiated rats

In the work presented here we paid our attention to studying changes of the activity of two lysosomal enzymes-acid phosphatase and beta-glucuronidase in platelets after whole-body irradiation and application of certain clinically applied antifibrinolytics (Antilysin Spofa and epsilon-aminocaproic acid) on the activity of these enzymes in isolated platelets. From the results it is obvious that the activity of acid phosphatase and beta-glucuronidase increases in platelets of irradiated rats with a maximum on the 11th day after irradiation. In the same time interval after irradiation the most remarkable thrombocytopenia was observed. The application of Antilysin or EACA to intact, non-irradiated rats affects remarkably neither the activity of the followed enzymes nor the count of platelets. A statistically significant thrombocytopenia, in a comparison with controls was found in whole-body irradiated rats who received EACA or Antilysin. The postirradiation increase of the level of acid phosphatase in platelets exerts a similar character in rats who received EACA or Antilysin as in those who were only irradiated with a difference that the increase of the level of this enzyme was essentially lower in all the time intervals of interest. The beta-glucuronidase level in platelets of rats, who received EACA, was essentially unchanged as compared to controls. The application of Antilysin altered remarkably the level of beta-glucuronidase in platelets of whole-body irradiated rats in a comparison with a level of this enzyme in platelets of rats who received no Antilysin. Most remarkable changes were observed in latter time intervals (11th and 15th day) when the beta-glucuronidase level in platelets of rats after the application of Antilysin was remarkably higher than that in solely irradiated rats.

Beta-glucuronidase in sera of patients with epileptic seizure activity, diabetes and some other disease states

As compared to controls and epileptics with controlled seizures, serum beta-glucuronidase enzyme is elevated significantly in epileptics with uncontrolled seizures. The enzyme begins to rise just before the seizure, remains elevated during, and for some time after the seizure and then begins to decline, unless another seizure follows the first seizure. The enzyme is not elevated in controlled diabetes patients without any secondary complications. But the enzyme is also elevated in other pathological conditions which involve increased connective tissue catabolism. However, the enzyme is elevated constantly and all the time in these conditions, in contrast with its elevation in uncontrolled epilepsy only close to the seizures.

Correlation of low and high affinity thiol methyltransferase and phenol methyltransferase activities in human erythrocyte membranes

Human red blood cell (RBC) membranes have been reported to contain both high and low affinity 'forms' of the drug metabolizing enzyme thiol methyltransferase (TMT). The biochemical characteristics of the two 'forms' of human RBC TMT were compared. Apparent Km constants of the high affinity activity for 2-mercaptoethanol and S-adenosyl-L-methionine, cosubstrates for the TMT reaction, were 0.38 mumol/l and 2.6 mumol/l, respectively. These constants may be compared with values of 20 mmol/l and 43 mumol/l, respectively, previously reported for the low affinity form of RBC TMT activity. The properties and regulation of the two forms of TMT were then compared with each other and also with those of two 'control' enzymes, phenol methyltransferase (PMT) and beta-glucuronidase. When high and low affinity TMT, PMT and beta-glucuronidase activities were measured in RBC membranes from 22 individual subjects, there were highly significant correlations among all three methyltransferase activities (all r values greater than 0.95), but beta-glucuronidase activity did not correlate significantly with any of the methyltransferase activities (all r values less than 0.40). The thermal stabilities of the three methyltransferases were very similar. They were all inactivated approximately 50% by incubation at 48 degrees C for 15 min. beta-Glucuronidase activity was approximately 50% inactivated by incubation at 76 degrees C for 15 min. PMT and both TMT activities had similar subcellular distributions and similar responses to ions and to enzyme inhibitors. These results suggested that high and low affinity TMT and PMT activities might be catalyzed by the same enzyme. Alternatively, these three RBC membrane methyltransferase activities might be regulated in a parallel fashion.

Effects of mitogenic stimulation of lymphocytes on lysosomal enzyme activity

Changes in the activities of several lysosomal enzymes were studied during transformation of mouse spleen cells in vitro. The activity of beta-glucuronidase increased during culture in the presence of T or B-cell mitogens, and lymphoblasts contained higher levels of activity than did small, non-transformed lymphocytes. Moreover, lymphoblasts in well-transformed cultures had higher activities than those in poorly-transformed cultures. The activities of other lysosomal enzymes (N-acetyl-beta-glucosaminidase, alpha-mannosidase, beta-glucosidase) also increased during mitogenic stimulation, but each at different rates, although aryl sulphatase was unaffected. Such differences may be of importance when lymphocytes are used for diagnosis of inherited lysosomal deficiency diseases.

In vitro effect of certain compounds on the lysosomal release of polymorphonuclear leukocytes

From studies on the release of acid phosphatase and B-glucuronidase, it was observed that quercetin, a vitamin P like compound and ascorbic acid stablise while dehydroascorbate, acetoacetate and B-hydroxybutyrate labilise the leukocytic lysosomes in vitro. These effects were compared with chloroquine and progesterone, known stabiliser and destabiliser, respectively. The possible mode of lysosomal labilisation by ketone bodies and dehydroascorbate has been suggested.