PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Subcellular Fractions”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 523 records · Page 29Linked to original sources

Immunoglobulin synthesis and secretion, IV. Sites of incorporation of sugars as determined by subcellular fractionation.

P(3)K cells were uniformly labeled with [(14)C]leucine and also for 1 hr with [(3)H]leucine, [(3)]galactose, or [(3)H]glucosamine. Subcellular fractionation of labeled cells was performed and the amounts of radioactive immunoglobulin G in each fraction were determined. The results indicate that amino acids are incorporated in the rough endoplasmic reticulum, galactose primarily in the smooth endoplasmic reticulum, and glucosamine at both sites. A small portion of radioactivity was found in the microsomal supernatant regardless of the radioisotope employed.

Animals↗

Studies on the appearance of chalone proteins in subcellular fractions from some bovine tissues. P. II Attempt of isolation of intracellular glycoproteins (chalone) from bovine spleen.

In the course of purification of chalone deriving from the subcellular fractions of bovine spleens, the butanol extraction of smooth and rough microsomes supernatants was performed. After extraction the lower layer was treated with SDS, buffered at pH 5,8. The homogeneity of obtained fractions was investigated by means of polyacrylamide electrophoresis. The antimitotic activity of fractions was performed by colcemide test in mice. There was stated that the cells of spleen contained two chalones. One of them showed antimitotic activity towards spleens of mice, the other towards lymph nodes. The former revealed on the polyacrylamide gel the mobility of gamma or beta, globulins, the later of prealbumins.

Animals↗

Localization of metallic ions with gingival fibroblast subcellular fractions.

Nickel-based alloys have been in use since the 1930s; however, there are concerns regarding the release of metal ions (Be(+2), Cr(+6), Cr(+3), Ni(+2), Mo(+6)) from these alloys into surrounding tissues. Therefore, the objective of this study was to determine the cellular location and accumulation of ions using atomic absorption spectroscopy and correlate location with the cytotoxic, morphologic, and ultrastructural evaluations reported previously. Human gingival fibroblasts were exposed to the metal ions for 72 h. Controlled atomic absorption spectroscopy studies were used to determine the intracellular location of these ions reported as parts per million metal ions per milligram protein. Enzymatic markers were shown to correspond to the appropriate fraction indicating success in fractionation of the gingival fibroblasts. These results correspond with the cytotoxic, morphologic, and ultrastructural alterations reported previously for fibroblasts exposed to these ions. The highest concentration of beryllium ions occurred in the low-density molecule fraction, where lipofuscin granules were found, which has been shown to contain metal ions. The highest concentrations of hexavalent chromium ions occurred in the plasma membrane and nuclear fractions followed by the mitochondria fraction, which is supported by the ions' ability to oxidize to trivalent chromium accumulating at the membrane as well as the alterations in nuclear and mitochondrial function. For trivalent chromium, the highest concentrations occurred in the low-density molecule and the plasma membrane fractions, which correlates with the ions' inability to readily cross membranes. The highest concentration of molybdenum ions occurred in the plasma membrane fraction correlating with alterations in membrane morphology and increased numbers of myelin figures. The highest concentration of nickel ions was associated with the cytosol fraction where lipid droplets seen in the transmission electron micrographs were located. The current study demonstrates that a successful subcellular fractionation was obtained on gingival fibroblasts and that the location of metallic ions within the fractions correlated with cellular alterations reported previously.

Beryllium↗

Oxalate-stimulation of ATP-dependent Ca-uptake is diminished during smooth muscle subcellular fractionation.

The ATP-dependent azide-insensitive Ca-uptake by the postnuclear supernatant from rat myometrium is stimulated more by 5 mM oxalate than by 25 mM phosphate. During subcellular fractionation, however, the percent recovery of the oxalate stimulated Ca-uptake diminishes more rapidly than that of the Ca-uptake without any added oxalate or phosphate. The percent recovery of the phosphate stimulated Ca-uptake also diminishes but not to as low levels as that of the oxalate stimulated Ca-uptake. The net result is higher stimulation of this uptake by 25 mM phosphate than by 5 mM oxalate in the various sucrose density gradient fractions. This discrepancy in percent recoveries presents a major concern about the use of oxalate or phosphate stimulated Ca-uptake as a marker for smooth muscle membranes.

Adenosine Triphosphate↗

[Intensification of peroxidation and changes in lipid composition in ischemic liver homogenates and subcellular fractions].

Lipid peroxidation (hydroperoxides and antioxidant activity) and lipid composition in liver homogenates and in its mitochondrial, microsomal and nuclear fractions were studied after 15--120 minutes of liver warm ischemia. Pronounced enhancement of lipid peroxidation during ischemia was seen in all subcellular fractions, particularly in the mitochondrial one. The results are consistent with low resistance of the liver and specifically its mitochondria to ischemia. Activation of lipid peroxidation corresponded with changes in the lipid composition. Decrease in the level of total and readily oxidizable lipids (cardiolipin) and accumulation of poorly oxidizable phospholipids (sphingomyelin) and highly toxic lysophosphatides were recorded. The evidence obtained suggests a role for lipid peroxidation in the pathogenesis of ischemic injuries to the liver.

Animals↗

Changes in electronegativity of lysosomal hydrolases during intracellular transport. An isoelectric-focusing study in subcellular fractions of rat kidney.

Isoelectric focusing was used to investigate the multiple forms of acid phosphatase, arylsulfatase, beta-glucuronidase, beta-galactosidase and beta-N-acetylhexosaminidase in the following, previously characterized subcellular fractions from rat kidney: a special rough microsomal fraction, enriched up to 9-fold over the homogenate in acid hydrolases; a smooth microsomal fraction; a Golgi membrane fraction enriched about 2.5-fold in acid hydrolases and 10- to 20-fold in several glycosyl transferases; and a lysosomal fraction enriched up to 25-fold in acid hydrolases. The electro-focusing behavior of the hydrolases in these fractions was markedly sensitive to the autolytic changes that occur under acidic conditions, even at 4 degrees C. Autolysis was minimized by extracting fractions in an alkaline medium (0.2% Triton X-100, 0.1 M sodium glycinate buffer, pH 10, 0.1 % p-nitrophenyloxamic acid) and adding p-nitrophenyloxamic acid (0.1 %), AN INHIBITOR OF LYSOSOMAL NEURAMINIDASE AND cathepsin D, to the pH gradient. The enzymes in the lysosomal fraction displayed a characteristic bimodal or trimodal distribution. Arylsulfatase, beta-glucuronidase and beta-N-acetylhexosaminidase occurred in an acidic form with an isoelectric point of 4.4, and a basic form with an isoelectric point of 6.2, 6.7 and 8.0, respectively. Acid phosphatase and beta-galactosidase occurred in an acidic, intermediate and basic form with isoelectric points of about 4. 1, 5.6 and 7.4, respectively. In the special rough microsomal fraction these enzymes were mostly in a basic form with isoelectric points between 7.5 and 9; these were 1-2 units higher than the corresponding basic forms in the lysosomal fraction. Treatment of extracts of the rough microsomal fraction with bacterial neuraminidase raised the isoelectric points of all five hydrolases by 1-2.5 units, indicating the presence of some N-acetylneuraminic acid residues in these basic glycoenzymes. The hydrolases in the Golgi fraction were largely in an acidic form with isoelectric points similar to or lower than those of the corresponding acidic components in the lysosomal fraction. The hydrolases in the smooth microsomal fraction showed isoelectric-focusing patterns intermediate between those in the rough microsomal and the Golgi fractions. These findings support the following scheme for the synthesis, transport and packaging of the lysosomal enzymes. Each hydrolase is synthesized in a restricted portion of the r

Acid Phosphatase↗

Subcellular fractionation and molecular characterization of the pellicle and plasmalemma of Neospora caninum.

A characteristic structural feature of Toxoplasma gondii and Neospora caninum is the presence of a triple-membrane pellicle, on the zoite stages of their complex life-cycle. Here we report the results of electron microscopic studies which show that the pellicle is made of a typical plasmalemma covered on its cytoplasmic side by a system of flattened vesicles named the inner membrane complex. Using methods described previously for the purification of pellicle and plasmalemma fractions from T. gondii, we have evaluated the same methodology for the preparation of pellicles and plasmalemma from N. caninum. The approach used involved subcellular fractionation and sucrose gradient centrifugation to prepare fractions containing pellicles. Plasmalemma was prepared by extraction of this fraction with a high salt glycerol treatment. Fractions containing membrane structures were identified by electron microscopy, and the proteins and antigens present in them were subsequently studied by SDS-PAGE and Western blotting. Electron microscopy of the pellicle fractions of N. caninum demonstrated preservation of the triple-membrane structure which is identical to that found in T. gondii. SDS-PAGE of the pellicle fractions revealed it contained several major proteins. Analyses revealed that the plasmalemma of N. caninum contained 2 abundant proteins in addition to other much lower abundance antigens detectable by monoclonal antibodies. These studies therefore report, for the first time, a detailed molecular characterization of the pellicle and plasmalemma of N. caninum.

Animals↗

Studies on the binding and distribution of radioactively labelled 3'-methylcholanthrene in subcellular fractions of rat liver.

The subcellular distribution of either [(14)C] or [(3)H]3'-methylcholanthrene was studied in rat liver following a single intraperitoneal injection of the labelled hydrocarbon 10 hours previously.Adsorbed or non-covalently bound methylcholanthrene and its metabolic derivatives occurred in all cell fractions studied with the exception of purified cell walls. The highest specific activities (d.p.m./mg. protein) were found in washed mitochondria, microsomes and ribosome-free microsomal membranes.Covalent binding of methylcholanthrene and its metabolic derivatives to different cell fractions of rat liver occurs to a small extent and is considered not to be significant. The highest degree of binding occurs in washed mitochondria, microsomes, ribosome-free microsomal membranes and their constituent core proteins.Cell sap which contains non-covalently bound 3'-methylcholanthrene was fractionated into pH 5 enzyme and pH 5 supernatant fractions. The pH 5 enzyme fraction which possesses a high specific activity (d.p.m./mg. protein) was further fractionated with ammonium sulphate into three fractions. The 0-30% ammonium sulphate fraction had the highest specific activity.

Adsorption↗

Non-NMDA excitatory amino acid receptors in a subcellular fraction enriched in cerebellar glomeruli.

In the internal granular layer of the cerebellar cortex the polysynaptic complexes called glomeruli consist mainly of homogeneous populations of glutamatergic and GABAergic synapses, both located on granule cell dendrites. A subcellular fraction enriched in glomeruli was prepared from rat cerebellum, and the distribution of the different types of NMDA and non-NMDA glutamate binding sites was studied in the membranes derived from this fraction (fraction G) as compared to that in the membranes prepared from a total cerebellar homogenate (fraction T). Cl-/Ca2+ independent [3H]glutamate binding sites were not abundant and could be reliably measured only in fraction G. Cl- dependent/Ca2+ activated [3H]glutamate binding sites were more abundant and exhibited a single KD in both fractions G and T. Quisqualate, NMDA, kainate, L-AP4 and trans-ACPD inhibited [3H]glutamate binding to different extents in the two membrane fractions. Quisqualate sensitive sites were predominant in all cases but more abundant in fraction T than in fraction G. An opposite distribution was observed for the NMDA sensitive binding sites while kainate sensitive binding sites were scarce everywhere. Trans-ACPD, a ligand presumed selective for metabotropic glutamate binding sites, displaced [3H]glutamate from fraction T but nor from fraction G, suggesting the absence of these sites from glomeruli. Similarly, no L-AP4 sensitive sites were present in fraction G while they were abundant in fraction T. Binding sites associated with ionotropic receptors of the quisqualate type were determined by measuring [3H]AMPA binding. The density of the high affinity [3H]AMPA binding sites in fraction T was twice as high as in fraction G, indicating that these sites are abundant in structures other than glomeruli.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Increase of cyclic AMP in subcellular fractions of rat heart muscle after beta-adrenergic stimulation: prenalterol and isoprenaline caused different distribution of bound cyclic AMP.

Although prenalterol is a partial beta-agonist, it has been reported to produce only a marginal, non-significant increase of cAMP in rat hearts. We studied the effect of prenalterol and isoprenaline on free and bound cAMP content in subcellular fractions of perfused rat hearts to see whether prenalterol increased cAMP and whether there were differences in the subcellular distribution of the cAMP contents after stimulation with the drugs. The in situ binding characteristics of cAMP to the protein kinases at different degree of beta-adrenergic stimulation were elucidated. Prenalterol increased significantly both total cAMP content in homogenate, bound cAMP in a 100,000 g particulate fraction and bound, free and total cAMP contents in the resulting supernatant. While prenalterol increased bound cAMP in the particulate fraction and in the supernatant proportionally, isoprenaline caused a relatively greater increase of bound cAMP in the supernatant. At equieffective concentrations regarding inotropic and lusitropic effects, prenalterol and isoprenaline increased bound cAMP in the particulate fraction to the same degree, while the increase in the other fractions was greater after isoprenaline. Thus, the cAMP bound in the particulate fraction seemed to determine the inotropic state of the cell after beta-adrenergic stimulation, supporting a compartmentation of cAMP in myocardium. In controls 31 to 34% of the total binding capacity for cAMP in the particulate fraction was occupied, increasing to 77% after maximal beta-stimulation. The binding capacity in the supernatant was only 15 to 18% saturated in the basal situation and about half saturated after maximal beta-stimulation. cAMP bound in the particulate fraction is of special interest when cAMP and functional effects are studied.

Animals↗

Muscimol and flunitrazepam binding sites in a subcellular fraction enriched in rat cerebellar glomeruli.

In the internal granular layer of the cerebellar cortex the polysynaptic complexes called glomeruli consist mainly of homogeneous populations of glutamatergic and GABAergic synapses, both located on granule cell dendrites. A subcellular fraction enriched in glomeruli was prepared from rat cerebellum, and the distribution of GABAA and of benzodiazepine binding sites between membranes derived from this fraction (fraction G) and from a total cerebellar homogenate (fraction T) was studied. The benzodiazepine and GABA binding sites were measured by the binding of agonists [3H]flunitrazepam and [3H]muscimol, respectively. The results indicate that both binding sites are present, but only slightly enriched, in the glomerular synapses. We found a muscimol/flunitrazepam binding site ratio of two, which is consistent with the enrichment of muscimol binding sites in the granular layer shown by both autoradiographic with radioactive glutamatergic ligands and in situ hybridization experiments respectively.

Animals↗

Subcellular fractions of vascular smooth muscle exhibiting calcium transport properties.

Vascular smooth muscle relies on two general sources of activator calcium, one the extracellular fluid and the other intracellular sites in the coupling between stimulation at the external membrane and tension development. Electron microscopic studies have demonstrated at least two subcellular elements, mitochondria and sarcoplasmic reticulum, that may participate in the release and/or sequestration of this activator calcium. In order to obtain quantitative answers to questions concerning the rates of calcium transport by these subcellular elements attempts to use differential centrifugation to obtain subcellular fractions from whole muscle homogenate have been reported. Mitochondrial enriched preparations have received little quantitative study as yet, although they possess active calcium uptake mechanisms. Nonmitochondrial preparations having active calcium uptake mechanisms have been found in a variety of smooth muscles. The method of preparation and properties of these nonmitochondrial preparations show a great deal of variation, indicating they are probably a heterogeneous mixture of sarcoplasmic reticulum and plasma membrane. Some preliminary experiments on the effects of vasoactive agents and cyclic AMP on the calcium transport by these nonmitochondrial preparations have yielded conflicting results. Resolution of these problems awaits clear identification of the calcium transport mechanisms with their appropriate subcellular structure.

Animals↗

Peroxisomes in molluscs, characterization by subcellular fractionation combined with western blotting, immunohistochemistry, and immunocytochemistry.

Peroxisomes of the digestive glands of mussels, Mytilus galloprovincialis Lmk, were investigated by immunoblotting and immunohistochemistry using rabbit antibodies against several mammalian hepatic peroxisomal proteins. Western blot analysis of main subcellular fractions revealed immunoreactive polypeptides with molecular weights comparable to those of the corresponding mammalian hepatic proteins. They could be localized to the peroxisomal matrix in the case of catalase, multifunctional enzyme (PH), and palmitoyl-CoA oxidase (AOX), and to the peroxisomal membrane in respect to PMP 70. The purification of peroxisomes by metrizamide density gradient centrifugation revealed the existence of two subpopulations with densities of 1.16 and 1.20 g cm(-3) exhibiting different protein compositions. In paraffin sections, positive immunolabeling for catalase was distributed along the apical cytoplasm of the epithelia of digestive ducts and stomach and throughout the cytoplasm of digestive tubule cells. The peroxisomal beta-oxidation enzymes, AOX and PH, also appeared predominantly in the ducts and the stomach epithelia with a weaker immunolabeling in the tubules. At the electron microscopic level a clear labeling with gold particles was observed in the peroxisomal matrix with the anti-guinea pig catalase antibody. In addition to peroxisomes, the anti-PH antibody also labeled the mitochondria. The similarity in the protein composition of molluscan and mammalian peroxisomes as revealed by the present study indicates that those proteins have been well conserved in evolution suggesting that functionally peroxisomes in molluscs could also be involved in the metabolism of lipids and in detoxification of xenobiotics. Thus, the antibodies tested could provide useful tools for detection of peroxisomal induction in molluscan biomonitoring programs for the assessment of aquatic environmental pollution.

Acetyl-CoA C-Acyltransferase↗

Increased stability of (+/-)-7 beta,8 alpha-dihydroxy-9 alpha,10 alpha-epoxy-7,8,9,10-tetrahydrobenzo [a]pyrene through interaction with subcellular fractions of rat liver.

The rate of hydrolysis of (+/-)-7 beta,8 alpha-dihydroxy-9 alpha,10 alpha-epoxy-7,8,9,10-tetrahydrobenzo [a]pyrene (BPDE) to tetrahydroxy derivatives (tetrols) in the presence of various subcellular fractions of rat liver was investigated. Microsomes and nuclei increased the half-life of BPDE in a concentration-dependent manner whereas cytosol had no such effect. The presence of 1 mg microsomal protein/ml increased the half-life of BPDE from 4 to 60 min at 22 degrees C and from 1.5 to 20 min at 37 degrees C. Nuclei equivalent of 500 micrograms DNA/ml increased the half-life from 1.9 to 3.6 min at 37 degrees C. Liposomes prepared from microsomal lipids mimicked the effect of microsomes indicating that BPDE is stabilized primarily by interacting with lipids. The significance of these interactions for the stability of BPDE in an intact cell system was evaluated by using isolated hepatocytes. In these cells the half-life of BPDE was substantially shorter (1 min at 5 X 10(6) cells/ml) than in buffer (3 min). However, hydrolysis of BPDE to tetrols was a minor reaction (less than or equal to 3% of added BPDE at a cell density greater than or equal to 5 X 10(6) cells/ml) and the main route of elimination (greater than or equal to 75%) was through conjugation with glutathione.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗

Studies on the stability of trans-alpha-acetoxytamoxifen in Sprague-Dawley female rat liver slices, homogenate and subcellular fractions including microsomes and mitochondria.

This work examined the stability of trans alpha-acetoxytamoxifen in Krebs-Henseleit buffer (pH 7.4), in the presence of Sprague-Dawley female rat liver slices, rat liver homogenate and hepatic subcellular fractions, including microsomes and mitochondria, at pH 7.4 and at 37 degrees C over 300 min. The rate of hydrolysis was determined using high-performance liquid chromatography, and degradation profiles were obtained from which the rate and order of degradation were both evaluated. By applying zero-, first-, second- and third-order models of drug disappearance and the generation of by-products, first- and second-order appeared to produce the best fit. trans-alpha-Acetoxytamoxifen degraded rapidly in buffer and more slowly in the biological systems, probably due to the fact that the agent partitions into the hydrophobic component of the biological tissue and hence degrades at a much slower rate. The principal degradation products were trans-alpha-hydroxytamoxifen and, to a lesser extent, cis-alpha-hydroxytamoxifen. Another peak could not be identified. The production of trans-alpha-hydroxytamoxifen was enhanced in the presence of biological enzymes, whereas the concentration of the cis isomer remains relatively constant in buffer only (pH 7.4) and in the presence of biological enzymes. Therefore, the formation of identical adducts with DNA is consistent, because it has been shown that alpha-acetoxytamoxifen breaks down to form alpha-hydroxytamoxifen in vitro. The percentage of trans-alpha-acetoxytamoxifen remaining after 300 min was 40% in mitochondria and 32% in homogenate. The half-life (t1/2) was calculated for each condition by applying zero-, first- and second-order rate kinetics.

Animals↗

Lysosomes in myocardial infarction: studies by means of cytochemistry and subcellular fractionation, with observations on the effects of methylprednisolone.

To evaluate lysosomal involvement in myocardial infarction, coronary artery thrombosis was induced by ligation in 16 dogs. Biopsies of infarcted and normal left ventricles were studied by ultrastructural cytochemistry and subcellular fractionation (0.25 M sucrose) from 30 min to 96 hrs post injury. Normal myocardium contained few "classical" (residual body) lysosomes: instead, acid phosphatase and aryl sulfatase were localized to longitudinal and to lateral sac elements of the sarcoplasmic reticulum. In postnuclear (450 X gm, 10 min) supernates, lysosomal acid phosphatase and beta-glucuronidase were divided 60:40 between sedimentable (98,000 X gm, 15 min) and non-sedimentable fractions of normal endocardium and epicardium (studied separately). At 2 hrs post infarction, ischemic muscle showed: 1) loss of membrane-bound acid phosphatase and aryl sulfatase; 2) mitochondrial damage; 3) loss of glycogen and disappearance of I but not A bands; and 4) entry into cells of colloidal lanthanum (= loss of plasma membrane integrity. Total lysosomal hydrolase did not increase until 6-5 hrs post infarct. At 2 hrs, significant increments (32 +/- 7%) were found in nonsedimentable acid phosphatase and beta-glucuronidase of endocardium (P less than 0.005 vs. normal) but the epicardium. In dogs given methylprednisolone (50 mg/k) 30 min post infarct, ultrastructural cytochemistry showed retention of lysosomal enzymes within endocardial sarcoplasmic reticulum and no significant redistribution of enzymes into non-sedimentable fractions (vs. eight paired, infarcted, untreated controls). Data show early disruption of lysosomes in myocardial infarction and their protection by steroid given after the acute insult.

Acid Phosphatase↗

Increased potential for NAD(P)H-dependent reactive oxygen species production of hepatic subcellular fractions of fish species with in vivo exposure to contaminants.

The present study investigated the proposed involvement of contaminant-stimulated reactive oxygen species (ROS) production in disease processes in fish. NAD(P)H-dependent ROS production of subcellular fractions was determined by the iron/EDTA-mediated oxidation of 2-keto-4-methiolbutyric acid. Hepatic cytosolic NADPH-dependent and microsomal NAD(P)H-dependent ROS production were increased 51-160% (P < 0.05) in rainbow trout (Oncorhynchus mykiss) 15 weeks after a single i.p. injection of polychlorobiphenyl (PCB) (100 mg Clophen A50 kg-1 wet wt.). Hepatic microsomal NADH-dependent ROS production was 114% higher in perch (Perca fluviatilis) from PCB-contaminated Lake Järnsjön compared to clean Lake Vänern, Sweden. Hepatic mitochondrial NADH-dependent, cytosolic NADH-dependent and microsomal NADPH-dependent ROS production were variously elevated up to 160% in flounder (Platichthys flesus) at various sites along two pollution transects near to the ports of Rotterdam and Amsterdam, Netherlands. Overall the data indicate increased potential for ROS production in liver of fish exposed to field pollution, and support the hypothesis of oxidative stress as a mechanism of contaminant-mediated disease in fish.

Animals↗

Sialidase in the guinea pig pulmonary parenchyma. Increased activity in the cytosolic and microsomal subcellular fractions after stimulation with Bacillus Calmette Guérin.

The sialidase activity was assayed in the guinea pig pulmonary parenchyma after removal of bronchoalveolar cells by washing. After differential centrifugation of the crude tissue homogenate, sialidase activities were measured in the subcellular fractions using the fluorogenic substrate 2-(4-methylumbelliferyl)-alpha-D-N-acetylneuraminate. Sialidase activities were found in the lysosomal-enriched (17,000 x g pellet), in the microsomal (105,000 x g pellet) and in the cytosolic (105,000 x g supernatant) fractions. Microsomal and lysosomal forms of sialidase had an optimum activity at pH 3.6-3.8, whereas the optimum for the cytosolic form was pH 4.6. The activity of all three forms was inhibited by Cu2+, whereas 1 mM Zn2+ and 0.5 mM Ca2+ activated the lysosomal and the cytosolic forms, respectively. In the crude homogenate taken from lungs of Bacillus Calmette Guérin-(BCG-) stimulated guinea pigs, the sialidase activity was increased by 43% (p = 0.025) 3 weeks after the end of the treatment. The cytosolic (+246%) and microsomal (+51%) sialidase activities were significantly increased, whereas the lysosomal sialidase activity was not changed significantly by BCG stimulation.

Animals↗