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S Moskalewski

Publications and source records attributed to S Moskalewski.

At least 19 recordsLinked to original sources
PubMed2001

Palmitic acid uptake by the rat soleus muscle in vitro.

Abstract: The rate of fatty acid uptake, oxidation, and deposition in skeletal muscles in relation to total and unbound to albumin fatty acids concentration in the medium were investigated in the incubated rat soleus muscle. An immunohistochemical technique was applied to demonstrate whether the albumin-bound fatty acid complex from the medium penetrates well within all areas of the muscle strips. It was found that the percentage of incorporation of palmitic acid into intramuscular lipids was fairly constant, independently of the fatty acid concentration in the medium, and amounted to 63-72% for triacylglycerols, 7-12% for diacylglycerols-monoacylglycerols, and 19-26% for phospholipids. Both palmitic acid incorporation into the muscle triacylglycerol stores and its oxidation to CO2 closely correlated with an increase in both total and unbound to albumin fatty acid concentrations in the incubation medium. Under conditions of increased total but constant unbound to albumin palmitic acid concentrations, the incorporation of palmitic acid into triacylglycerols and its oxidation to CO2 were also increased, but to a lower extent. This supports the hypothesis that the cellular fatty acid metabolism depends not only on the availability of fatty acids unbound to albumin, but also on the availability of fatty acids complexed to albumin.

Animals↗
PubMed2001

Cartilage produced after transplantation of syngeneic chondrocytes is rejected in rats presensitized with allogeneic chondrocytes.

Cartilage produced in 2-week-old intramuscular transplants of syngeneic chondrocytes in rats did not display any signs of rejection. Cartilage produced by similar transplants in animals presensitized with intramuscular transplants of allogeneic chondrocytes was surrounded by infiltrations composed mainly of lymphocytes and was partially resorbed. Spleen mononuclear cells (SMC) from recipients of syngeneic transplants alone were not stimulated in mixed splenocyte-chondrocyte cultures by syngeneic or allogeneic chondrocytes. SMC from recipients of allogeneic and subsequent syngeneic transplants were strongly stimulated by both syngeneic and allogeneic chondrocytes, although stimulation by the latter was significantly more pronounced. Sera from naive rats usually contained cytotoxic antichondrocyte antibodies but their level varied considerably in various individuals. In rats chosen as transplant recipients on the basis of low antichondrocyte cytotoxicity of their sera, this toxicity was markedly raised after sensitization with allo- and syngeneic chondrocytes. Absorption with thymocytes or fibroblasts decreased but did not abrogate cytotoxicity. These observations support previous reports suggesting expression of tissue-specific antigen(s) by chondrocytes.

Animals↗
PubMed2000

[Molecular basis of achondroplasia, hypochondroplasia, and thanatophoric dysplasia].

Fibroblast growth factor 2 (FGF2) inhibits proliferation and hypertrophy of chondrocytes in the growth plate, synthesis of cartilage matrix, terminal differentiation of hypertrophic chondrocytes and matrix calcification. Recent studies have found that mutations in the receptor for fibroblast growth factor 3 (FGFR3) cause achondroplasia, hypochondroplasia and thanatophoric dysplasia. These mutations evoke uncontrolled stimulation of the receptor, leading to inhibition of bone growth. Inactivation of the receptor in experimental animals causes excessive chondrocyte proliferation and abnormal bone length. Chondrocyte stem cells proliferate in the ossification groove of Ranvier and contribute to both peripheral and longitudinal growth of the growth plate. They express FGFR3, have a potential to differentiate into chondrocytes and are therefore considered adequate for healing cartilage defects in the articular surface. It is at present unknown what happens to the chondrocyte precursor cells in the ossification groove of patients with FGFR3 mutation.

Achondroplasia↗
PubMed1999

Role of microtubules in the organization of the Golgi complex.

The Golgi complex of mammalian cells is composed of cisternal stacks that function in processing and sorting of membrane and luminal proteins during transport from the site of synthesis in the endoplasmic reticulum to lysosomes, secretory vacuoles, and the cell surface. Even though exceptions are found, the Golgi stacks are usually arranged as an interconnected network in the region around the centrosome, the major organizing center for cytoplasmic microtubules. A close relation thus exists between Golgi elements and microtubules (especially the stable subpopulation enriched in detyrosinated and acetylated tubulin). After drug-induced disruption of microtubules, the Golgi stacks are disconnected from each other, partly broken up, dispersed in the cytoplasm, and redistributed to endoplasmic reticulum exit sites. Despite this, intracellular protein traffic is only moderately disturbed. Following removal of the drugs, scattered Golgi elements move along reassembling microtubules back to the centrosomal region and reunite into a continuous system. The microtubule-dependent motor proteins cytoplasmic dynein and kinesin bind to Golgi membranes and have been implicated in vesicular transport to and from the Golgi complex. Microinjection of dynein heavy chain antibodies causes dispersal of the Golgi complex, and the Golgi complex of cells lacking cytoplasmic dynein is likewise spread throughout the cytoplasm. In a similar manner, kinesin antibodies have been found to inhibit Golgi-to-endoplasmic reticulum transport in brefeldin A-treated cells and scattering of Golgi elements along remaining microtubules in cells exposed to a low concentration of nocodazole. The molecular mechanisms in the interaction between microtubules and membranes are, however, incompletely understood. During mitosis, the Golgi complex is extensively reorganized in order to ensure an equal partitioning of this single-copy organelle between the daughter cells. Mitosis-promoting factor, a complex of cdc2 kinase and cyclin B, is a key regulator of this and other events in the induction of cell division. Cytoplasmic microtubules depolymerize in prophase and as a result thereof, the Golgi stacks become smaller, disengage from each other, and take up a perinuclear distribution. The mitotic spindle is thereafter put together, aligns the chromosomes in the metaphase plate, and eventually pulls the sister chromatids apart in anaphase. In parallel, the Golgi stacks are broken down into clusters of vesicles and tubules and movement of protein along the exocytic and endocytic pathways is inhibited. Using a cell-free system, it has been established that the fragmentation of the Golgi stacks is due to a continued budding of transport vesicles and a concomitant inhibition of the fusion of the vesicles with their target membranes. In telophase and after cytokinesis, a Golgi complex made up of interconnected cisternal stacks is recreated in each daughter cell and intracellular protein traffic is resumed. This restoration of a normal interphase morphology and function is dependent on reassembly of a radiating array of cytoplasmic microtubules along which vesicles can be carried and on reactivation of the machinery for membrane fusion.

Animals↗
PubMed1998

Partitioning of cytoplasmic organelles during mitosis with special reference to the Golgi complex.

During mitosis, not only the genetic material stored in the nucleus but also the constituents of the cytoplasm should be equally partitioned between the daughter cells. For this sake, the dividing cell goes through an extensive structural reorganization and transport along the endocytic and exocytic pathways is temporarily arrested. Early in prophase, the radiating array of cytoplasmic microtubules disassembles and the membrane systems of the secretory apparatus start to split up. In metaphase, the nuclear envelope fragments and the condensing chromosomes associate with the forming mitotic spindle. The cisternal and tubular elements of the endoplasmic reticulum and the Golgi complex break down into small vesicles, presumably as the result of an imbalance between vesicle budding and fusion. In anaphase, the two sets of chromosomes are pulled apart and a cleavage furrow forms halfway between the spindle poles. Since most organelles occur in multiple and widely dispersed copies at this stage, they will be evenly distributed between the daughter cells. During telophase and cytokinesis, the preceding fragmentation process is reversed. A nuclear envelope reappears around the chromosomes and cytoplasmic microtubules reassemble. The endoplasmic reticulum is rebuilt as a continuous system of flattened cisternae and tubules. Stacks of Golgi cisternae arise from small vesicles and are rearranged in an interconnected network. In parallel, the biosynthetic functions of the cell are normalized and intracellular membrane traffic is resumed.

Cell Compartmentation↗
PubMed1996

Concomitant staining of mast and parietal cells in human gastric mucosa.

A simple technique for concomitant staining of mast and parietal cells in the same section is described. Mast cells were stained by alcian blue or astra blue in methanol-formalin-acetic acid fixed biopsies of gastric mucosa. Parietal cells were visualized by Dolichos biflorus lectin binding.

Alcian Blue↗
PubMed1996

Formation of lamellar bone on the surface of woven bone is not prevented by BAPN.

To study the possible effect of collagen cross-link formation on the lamellar bone deposition, isolated mouse bone cells were transplanted in the syngeneic system and the formation of bone was followed in control and beta-aminopropionitrile (BAPN) treated animals. Woven and lamellar bone were distinguished by shape of bone lacunae, PAS reaction and Sirius red staining of collagen fibers. BAPN was administered in various doses either subcutaneously or in drinking water. Bone formed in BAPN treated animals contained both woven and lamellar bone in similar proportion as in controls. Thus, cross-linking of collagen seems to be unnecessary for lamellar bone deposition.

Aminopropionitrile↗
PubMed1995

Rejection of cartilage formed by transplanted allogeneic chondrocytes: evaluation with monoclonal antibodies.

Cellular infiltrates participating in rejection of cartilage formed by transplanted allogeneic rat epiphyseal chondrocytes were evaluated immunohistochemically using a panel of different monoclonal antibodies. One week after transplantation, the grafts were surrounded by numerous class II MHC+ (OX6+, OX17+), CD4+ (W3/25+), and W3/13+ cells as well as some ED1+ monocytes/macrophages. Only a few T (OX19+) and B (HIS14+) cells were present. The number of class II MHC+ cells and ED1+ monocytes/macrophages did not change significantly in the course of rejection whereas the number of CD4+ and W3/13+ cells gradually decreased. On the other hand, there was a significant increase in the number of CD8+ (OX8+) cells. CD8+ cells accumulated close to the transplants and some of them penetrated cartilage matrix suggesting that they might be involved in chondrocyte killing. After 3 months, cartilage was almost completely destroyed and the intensity of infiltrations was markedly decreased. Fibrous connective tissue predominated, however, some class II+ as well as few ED1+, CD4+ and CD8+ cells were still present adjacent to the cartilage remnants. At the time of transplantation, chondrocytes were endowed with RT1.D class II antigen (OX17+), but they did not react with OX6 mAb (monoclonal antibody) recognizing the RT1.B class II molecule. However, after 1 week, some chondrocytes reacted with OX6 mAb and the number of RT1.B positive chondrocytes increased in the course of cartilage rejection.

Animals↗
PubMed1995

[Draize test and alternative methods for evaluating irritation from chemical substances].

The eye irritancy test in rabbits (Draize test) is currently the method used to evaluate the hazard or safety of chemical substances. To reduce the need for animal testing some new procedures as alternative were elaborated. We present a review of method used as well as evaluation of sensitivity and repeatability of alternative tests applied in laboratories of European Economic Communities.

Animal Testing Alternatives↗
PubMed1994

Functions of the Golgi complex in cell division: formation of cell-matrix contacts and cell-cell communication channels in the terminal phase of cytokinesis.

The Golgi complex of mammalian cells is disorganized into dispersed vesicular and tubular elements during mitosis and is then reorganized into an interconnected system of cisternal stacks in each daughter cell during cytokinesis. Recent studies further indicate that the Golgi complex is typically relocated from the proximal to the distal side of the nucleus in the terminal phase of cytokinesis (as related to the intercellular bridge). Here, the functional role of this shift in position was approached using rat embryo fibroblasts synchronized with thymidine and nocodazole. Mitotic cells were collected by shaking and seeded in medium without or with brefeldin A (a fungal metabolite that inhibits protein secretion). They were fixed after one or two hours and stained for immunocytochemical demonstration of mannosidase II (a Golgi protein), fibronectin (an extracellular matrix protein), the fibronectin receptor (a member of the integrin family of proteins), and connexin 43 (a member of the connexin family of gap junction proteins). One hour after seeding, the cells had completed mitosis and progressed into cytokinesis. The Golgi complex was now usually located on the proximal side of the nucleus and overlapping fibrillar arrays of fibronectin and fibronectin receptors were observed in the contact zone between the daughter cells, while connexin 43 mainly occurred in fine dispersed spots. Two hours after seeding, the cells had spread out on the substrate and started to move apart. The Golgi complex was now usually located on the distal side of the nucleus. Moreover, fibronectin and fibronectin receptors were found to codistribute both in the contact zone between the daughter cells and in adhesive contacts beneath them, while connexin 43 was concentrated to plaques in the former zone. After treatment with brefeldin A, there was a diffuse cytoplasmic staining for mannosidase II and fibronectin and no distinct extracellular staining for fibronectin was noted. In addition, the connexin 43 positive plaques were reduced in size and number. Although the cells completed cytokinesis in the presence of the drug, they showed an increased tendency to detach from the substrate and locate on top of each other rather than to move apart normally. Taken together, the observations suggest that the change in position of the Golgi complex during cytokinesis serves the function to direct transport of secretory proteins as well as membrane constituents to different parts of the cell surface at different times.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1993

Relationship between the Golgi complex and microtubules enriched in detyrosinated or acetylated alpha-tubulin: studies on cells recovering from nocodazole and cells in the terminal phase of cytokinesis.

Double immunofluorescence microscopy was used to study the relationship between the Golgi complex and microtubules enriched in posttranslationally modified tubulins in cultured mouse L929 fibroblasts. In interphase cells, the elements of the Golgi complex were grouped around the microtubule-organizing center. From here, tyrosinated microtubules extended to the periphery of the cells, whereas the distribution of detyrosinated and acetylated microtubules largely overlapped with that of the Golgi complex. Treatment of cells with 10 microM nocodazole led to the disruption of all microtubules and dispersion of the Golgi elements. Following withdrawal of the drug, tyrosinated microtubules reformed first, followed by acetylated and then detyrosinated microtubules. In parallel, the Golgi elements moved back toward the juxtanuclear region and reestablished a close spatial relationship first with the acetylated and later also with the detyrosinated microtubules. Long-term recovery in the presence of 0.15 or 0.3 microM nocodazole allowed partial reformation of tyrosinated and acetylated microtubules, whereas no or only a few detyrosinated microtubules were detected. At the same time, the Golgi elements were grouped closer together around or on one side of the nucleus in close relation to acetylated microtubules. In synchronized cells released from a mitotic block, a radiating array of tyrosinated microtubules was first formed, followed by acetylated and detyrosinated microtubules. The Golgi elements initially came together in a few groups and thereafter took an overall morphology similar to that in interphase cells. During this reunification, they showed a close spatial relationship to acetylated microtubules, whereas detyrosinated microtubules appeared only later. Microtubules enriched in acetylated and/or detyrosinated tubulin thus appear to take part in establishing and maintaining the organization of the Golgi elements within an interconnected supraorganellar system. Whether the acetylation and detyrosination of tubulin are directly involved in this process or merely represent two modifications within this subpopulation of microtubules remains unknown.

Acetylation↗
PubMed1993

Microwave-assisted staining of mucosal mast cells and granulated intra-epithelial lymphocytes after formalin fixation.

Rat jejunum was fixed with either formalin or methanol-formalin acetic acid (MFAA) and stained with Astra Blue or Alcian Blue with or without microwave irradiation. Staining of both mucosal mast cells and granulated intra-epithelial lymphocytes after formalin fixation was considerably improved by microwave irradiation. On the other hand, microwave irradiation slightly impaired staining of mucosal mast cells (MMC) and even more strongly granulated intra-epithelial lymphocytes (GIEL) after MFAA fixation.

Acetates↗
PubMed1993

Influence of liver environment on the maturation of isolated epiphyseal chondrocyte transplants.

To study the phenomenon of chondrocyte hypertrophy, rat or mouse isolated epiphyseal chondrocytes were transplanted into the kidney, spleen or liver for 7 days. Each transplant had its own control transplanted intramuscularly. Rat chondrocytes were also placed on a chorioallantoic membrane of chick embryos, incubated for 11 days and transferred for the next 11 days either onto another chorioallantoic membrane or into rat muscle. The surface area of largest lacunae cross-sections in cartilage produced by transplants was measured as an indicator of chondrocyte hypertrophy. In cartilage from the chorioallantoic membrane chondrocytes remained small but hypertrophied after transfer into a muscle. Lacunae in seven-day-old cartilage nodules in the liver were considerably larger than in muscle, kidney or spleen. After 7 days matrix calcification was observed only in liver transplants. Thus, liver environment, stimulated chondrocyte hypertrophy. Taken together these results suggest that chondrocytes are unable to hypertrophy spontaneously and that the rate of hypertrophy is subjected to regulation by extra-cartilaginous factor(s).

Animals↗
PubMed1992

Disorganization of the Golgi complex and the cytoplasmic microtubule system in CHO cells exposed to okadaic acid.

A combination of immunocytochemical and electron microscopic methods was used to study the effects of okadaic acid, a specific inhibitor of protein phosphatase types 1 and 2A, on the Golgi complex and the microtubule system of interphase CHO cells. At a concentration of 0.25 microM and within 2-3 h of exposure, okadaic acid caused a reversible disorganization of the Golgi complex, observed as a disintegration of the stacks of cisternae and formation of clusters of tubules and vesicles dispersed in the cytoplasm. At the same time, staining for mannosidase II was shifted from the Golgi stacks to the endoplasmic reticulum, whereas the clusters of tubules and vesicles for the main part were negative. This change in localization of the enzyme was not blocked by cycloheximide and thus not dependent on ongoing protein synthesis. The changes in the morphology of the Golgi complex were coordinated in time with a remodelling of the microtubule system, observed as a reduction in the number of microtubules, a tendency of the remaining microtubules to arrange in an aster-like pattern, and an increased sensitivity to low concentrations of the microtubule-disruptive drug nocodazole. After removal of the drug, the microtubule system was rapidly normalized (1-2 h) and subsequently also the Golgi complex (4-8 h). The results suggest that okadaic acid induces a redistribution of the Golgi stacks into the endoplasmic reticulum, leaving the trans-most elements behind as tubules and vesicles.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Synchronized shift in localization of the Golgi complex and the microtubule organizing center in the terminal phase of cytokinesis.

As mammalian cells enter mitosis, the Golgi complex is disorganized and the remnants are dispersed throughout the cytoplasm in the form of a few short cisternae and small clusters of vesicles. Once the separation of the chromosomes is completed and nuclei reform, stacks of flattened cisternae reappear and a united Golgi complex of interphase type starts to be reorganized. This process is believed to ensure an approximately equal partitioning of the Golgi complex on the daughter cells. Here, the configuration of the Golgi complex and its relation to the cytoplasmic microtubule system was studied at the end of cytokinesis using synchronized cultures of L929 mouse fibroblasts and rat dermal fibroblasts. One hour after the release of the mitotic block, the Golgi complex (visualized immunocytochemically with antibodies against mannosidase II) was most frequently located on the proximal side of the nucleus as related to the intercellular bridge (visualized immunocytochemically with antibodies against tyrosinated alpha-tubulin). One hour later, it was preferentially found on the distal side of the nucleus as related to the intercellular bridge. Immunocytochemical demonstration of the radiating pattern of microtubules, and direct demonstration of the centrioles using antibodies against detyrosinated or acetylated alpha-tubulin, showed that the microtubule organizing center (MTOC) shifted position in a similar manner as the Golgi complex. Moreover, double staining with antibodies against mannosidase II and tyrosinated alpha-tubulin revealed that the Golgi complex and the MTOC codistributed at both times after the release of the mitotic block. Electron microscopic analysis confirmed that the reforming Golgi stacks first gathered close to the centrosome (a pair of centrioles with associated structures, constituting the main MTOC in the cell) on the proximal side of the nucleus and that the Golgi stacks and the centrosome were subsequently both relocated to the distal side of the nucleus as related to the intercellular bridge. Taken together, the findings indicate that the Golgi complex goes through a characteristic translocation in the terminal phase of cytokinesis and confirm the idea that the cytoplasmic microtubule system plays an important role in the organization of this organelle system. A possible function of the shift in location of the Golgi complex at the end of cytokinesis could be to direct membrane traffic first to the elongating intercellular bridge and thereafter to the leading edge as the cells are about to separate and move away from each other.

Animals↗
PubMed1992

Reorganization of the Golgi complex in association with mitosis: redistribution of mannosidase II to the endoplasmic reticulum and effects of brefeldin A.

Previous studies have shown that the Golgi complex is broken down into dispersed clusters of vesiculotubular elements as mammalian cells enter mitosis and is reformed in each daughter cell in telophase/cytokinesis. In the present investigation, mannosidase II (a membrane-bound enzyme involved in oligosaccharide processing) was used as a marker to explore the fate of the Golgi complex in dividing L929 and CHO cells in some additional detail. Immunofluorescence microscopy demonstrated a juxta- or perinuclear staining for mannosidase II (man II) in interphase and immunoelectron microscopy revealed that it was restricted to the stacked Golgi cisternae at this stage. As the cells entered mitosis, the staining for man II assumed a pattern of dispersed elements in prophase and then turned into a diffuse pattern during metaphase and anaphase. At the electron microscopic level, this corresponded to a successive disorganization of the Golgi complex, first into structurally modified stacks scattered throughout the cytoplasm, and thereafter into small clusters of vesicles and tubules. In parallel, most of the immunoreactivity for man II was shifted into partially fragmented cisternae of endoplasmic reticulum, and only small amounts were found in the clusters just mentioned. During telophase/cytokinesis a circumscribed staining for man II reappeared in each daughter cell. At the electron microscopic level, cisternal stacks positive for man II were found to reform at the same time as immunoreactivity disappeared from the endoplasmic reticulum. Typically, the Golgi region was first located on the proximal side of the nucleus as related to the intercellular bridge, and then moved to the distal side of the nucleus before the cells were about to separate. Treatment of synchronized mitotic cells with brefeldin A, a fungal metabolite that inhibits endoplasmic reticulum to Golgi transport, prevented reformation of the Golgi complex in telophase/cytokinesis. Nevertheless, the separation of the daughter cells was completed at a similar rate as in the controls. On the basis of these findings, an extended model of the disorganization and reorganization of the Golgi complex in association with mitosis is presented. According to this model the disorganization of the Golgi complex at the onset of mitosis is a two-step process: the Golgi stacks are first separated from each other and spread out in the cytoplasm; thereafter the Golgi stacks disintegrate, at least in part by return of Golgi components to the endoplasmic reticulum. In interphase cells, similar changes in the organization of the Golgi complex are produced by microtubule-disruptive drugs (dispersion of the stacks) and brefeldin A (redistribution of Golgi proteins into the endoplasmic reticulum), respectively.

Animals↗