Biomedical subjects

S Krajewski

Publications and source records attributed to S Krajewski.

At least 163 records · Page 9Linked to original sources

PubMed1995

Immunohistochemical analysis of the Bcl-2 oncoprotein in human neuroblastomas. Comparisons with tumor cell differentiation and N-Myc protein.

BACKGROUND: The bcl-2 gene encodes a 26-kilodalton integral membrane oncoprotein that is noteworthy for its function as a blocker of programmed cell death, and ability to render cells resistant to killing by chemotherapeutic drugs and x-irradiation. EXPERIMENTAL DESIGN: To determine the in vivo patterns of bcl-2 expression in neuroblastomas (NBs), tumor specimens derived from 17 children with NB or ganglioneuromas were immunohistochemically evaluated using formalin-fixed, paraffin-embedded material and antibodies specific for the Bcl-2 and N-Myc proteins, or various markers typically used to assess the differentiation status of these tumors, including neuron-specific enolase, S-100 protein, beta 2-microglobulin (beta 2M) and the intermediate filament proteins, vimentin, and neurofilament light- and medium-chains. RESULTS: Using two-color immunohistochemical methods, Bcl-2 protein was found exclusively in tumor cells that did not contain N-Myc, an oncoprotein previously associated with poor prognosis in NB. Levels of Bcl-2 immunostaining were heterogeneous in the undifferentiated small, round cells typically seen in tumors with aggressive histology, and ranged from essentially undetectable, to strong in intensity. Somewhat higher levels of Bcl-2 immunostaining were found in the slightly larger, more differentiated neuroblastic cells that had more generous cytoplasm in these neoplasms. In contrast to the heterogeneous levels of Bcl-2 seen in undifferentiated NBs, Bcl-2 immunoreactivity was uniformly present at high levels in tumor cells that were more differentiated and judged to be similar to immature ganglion cells at an intermediate stage of neuronal differentiation, based on morphologic characteristics and immunophenotyping with antibodies specific for various differentiation markers. The still more differentiated ganglionic cells seen in ganglioneuroblastomas and ganglioneuromas exhibited much less intense immunoreactivity with anti-Bcl-2 antibodies, suggesting down-regulation of bcl-2 during final terminal differentiation. In contrast to cells with neuronal features, the stromal Schwann cells were uniformly negative for Bcl-2 protein in all histologic grades of tumors. Thus, bcl-2 expression in NBs was limited to cells of the neuronal lineage and tended to be highest in tumor cells with the characteristics of ganglionic cell precursors. The expression of bcl-2 in the normal fetal and postnatal adrenal medulla and sympathetic ganglia paralleled that seen in NBs, consistent with previous suggestions that NB reflects a block in the normal differentiation process. CONCLUSIONS: Taken together, these findings indicate that the levels of the Bcl-2 protein are developmentally regulated in normal and neoplastic cells of the sympathetic branch of the autonomic nervous system, and suggest that this oncoprotein may be useful as a differentiation marker for subclassification of NBs for prognostic purposes and for investigations of normal neuronal maturation. Furthermore, strong Bcl-2 immunoreactivity was detected in islets of residual tumor cells in 6 of 7 specimens obtained from 5 patients after therapy, suggesting that this oncoprotein may be cytoprotective for NB cells in vivo.

Adolescent↗

PubMed1994

Regulation of neuronal Bcl2 protein expression and calcium homeostasis by transforming growth factor type beta confers wide-ranging protection on rat hippocampal neurons.

Excessive activation of glutamate receptors accompanied by Ca2+ overloading is thought to be responsible for the death of neurons in various conditions including stroke and epilepsy. Neurons also die if deprived of important growth factors and trophic influences, conditions sensitive to certain oncogene products such as the Bcl2 protein. We now demonstrate that transforming growth factor type beta (TGF-beta) prevents neuronal Ca2+ overloading of rat hippocampal neurons in response to the glutamatergic agonist N-methyl-D-aspartate or the Ca2+ ionophore 4-Br-A23187 and, in addition, leads to a substantial increase in neuronal Bcl2 protein expression. Parallel cytotoxicity experiments demonstrate that treatment with TGF-beta protects rat hippocampal neurons from death induced by excitotoxicity, trophic factor removal, and oxidative injury. Thus, TGF-beta may protect against a wide range of toxic insults by regulating two factors with great importance for neuronal viability.

Animals↗

PubMed1994

Immunohistochemical analysis of in vivo patterns of Bcl-X expression.

The in vivo patterns of bcl-X gene expression were assessed in human and mouse tissues using an immunohistochemical approach. Polyclonal antisera were raised against synthetic peptides corresponding to amino acids 46-66 and 61-79 of the human Bcl-X protein and were shown to be specific for detection of human and mouse Bcl-X-L and Bcl-X-S proteins by immunoblotting. Bcl-X immunoreactivity was detected in a wide variety of cell types and was typically present in the cytosol in a punctate pattern suggestive of association with intracellular organelles. Among the cell types with prominent Bcl-X immunostaining were: (a) a variety of neuronal populations in the brain as well as sensory neurons in dorsal root ganglia; (b) cortical (but not medullary) thymocytes and activated lymphocytes and plasma cells in lymph nodes; (c) several types of cells in the bone marrow, including megakaryocytes, red cell precursors, and some types of differentiating myeloid cells; (d) reproductive tissues, including the spermatocytes and spermatids in the testes and germinal epithelium of the ovary; and (e) a variety of epithelial cells including mammary epithelium, the secretory epithelial and basal cells of the prostate, uterine endometrium, gastric and intestinal epithelial cells, renal tubule epithelium, and differentiated keratinocytes in the upper layers of the epidermis but not in the basal cells. In many cases, these patterns of Bcl-X expression were strikingly different from those reported previously for Bcl-2, suggesting that Bcl-X and Bcl-2 regulate cell life and death at different stages of cell differentiation through tissue-specific control of their expression.

Amino Acid Sequence↗

PubMed1994

Interleukin 7-dependent B lymphocyte precursor cells are ultrasensitive to apoptosis.

We have compared the sensitivity of clonogenic interleukin 7 (IL-7)-dependent murine B cell precursors with that of clonogenic mature B cells and myeloid precursors to alpha-particles from plutonium-238 and X radiation. All three populations are relatively sensitive, but B cell precursors are ultrasensitive. This differential sensitivity is also observed with corticosteroid, etoposide, and cisplatin, all apoptosis-inducing drugs used in the treatment of leukemia and other cancers. Further, we show that x-rays and drugs induce the bulk of the B cell precursor population to undergo rapid apoptosis, despite the continued presence of IL-7. B cell precursors were found to express very low levels of BCL-2 protein compared with mature splenic B cells and their resistance to x-rays and corticosteroid could be enhanced by expression of a BCL-2 transgene. These data have important implications for normal lymphopoiesis and for the behavior of leukemic lymphoid precursor cells.

Alpha Particles↗

PubMed1994

Cloning and sequencing of a cDNA encoding the rat Bcl-2 protein.

A rat cDNA encoding the Bcl-2 protein was cloned and sequenced. The primary amino-acid sequence deduced from the nucleotide sequence reveals a 236-aa protein having extensive homology with the mouse (95%), human (87%) and chicken (71%) Bcl-2 proteins.

Amino Acid Sequence↗

PubMed1994

Evolutionary conservation of function among mammalian, avian, and viral homologs of the Bcl-2 oncoprotein.

The bcl-2 gene was originally cloned because of its involvement in B-cell lymphomas and encodes a 25-kD integral membrane protein that has been shown to inhibit programmed cell death (also termed apoptosis) in a wide variety of circumstances. The Epstein-Barr Virus (EBV) also has been implicated in B-cell malignancies and interestingly contains an open reading frame (BHRF-1) predicting a 19-kD protein with 22% homology to Bcl-2. To compare the functions of p26-Bcl-2 and p19-BHRF-1, we stably introduced expression plasmids encoding these proteins into a murine interleukin-3 (IL-3)-dependent hemopoietic cell line, 32D. Removal of IL-3 from cultures of control-transfected 32D cells resulted in internucleosomal DNA cleavage (a hallmark of programmed cell death) and loss of cell survival. In contrast, 32D cells containing high levels of p26-Bcl-2 or p19-BHRF-2 proteins exhibited prolonged survival and markedly delayed DNA degradation under the same conditions of IL-3 deprivation. As a first attempt to determine the functional importance of amino acid sequences that are conserved between the Bcl-2 and BHRF-1 proteins, we used site-specific mutagenesis to replace two conserved cysteine residues with alanines (positions 158 and 219) in the human Bcl-2 protein. Comparisons of the wild-type and cysteine-minus human Bcl-2 proteins in S49 lymphoma cells revealed equivalent ability to block glucocorticoid-induced cell death and DNA fragmentation, indicating that these two conserved cysteines are not critical for Bcl-2 oncoprotein function. Investigations in 32D cells of an avian homolog of Bcl-2 cloned from the chicken also revealed conservation of function with the human Bcl-2 protein, despite the presence of a 48-amino-acid region of divergent sequence. Taken together, these data demonstrate that despite marked differences in their predicted amino-acid sequences, the human, chicken, and EBV versions of Bcl-2 have retained the structural characteristics necessary to interface with pathways involved in the regulation of programmed cell death in murine cells. The findings thus contribute to the mapping of functional domains in Bcl-2 proteins, and raise the possibility that the EBV-encoded p19-BHRF-1 protein may be able to substitute for p26-Bcl-2 in the development of some types of cancer.

Amino Acid Sequence↗

PubMed1994

Bcl-2 protein localizes to the chromosomes of mitotic nuclei and is correlated with the cell cycle in cultured epithelial cell lines.

bcl-2 gene expression confers a survival advantage by preventing cells from entering apoptosis. In contrast to the previously described cytoplasmic localization of Bcl-2 in epithelial cells in vivo, in this study we have demonstrated, in a series of human epithelial cell lines, that Bcl-2 also localizes to mitotic nuclei. Both immunocytochemical and immunoelectron microscopical examinations localize this protein to nuclei and in particular to chromosomes. Nuclear Bcl-2 expression in these cell lines is correlated with the cell cycle. There is relatively strong expression during mitosis, most intense during prophase and metaphase, declining in telophase and then the protein becomes undetectable soon after separation of the two daughter cells. The expression and distribution of Bcl-2 is influenced by treatment with excessive thymidine. These results indicate that Bcl-2 may protect the cells from apoptosis occurring during mitosis and suggest a possible role for the protein in cell immortalization.

Cell Cycle↗

PubMed1994

Pre- and postnatal blood vessel development of the human spinal cord: association with myelination.

The material comprised spinal cord segments C8 or Th1 of 5 human fetuses aged from 18 up to 34 weeks and 6 infants aged from one day to 3 years. On formalin-fixed paraffin-embedded sections, peroxidase-antiperoxidase Sternberger's et al. (1970) method for visualization of blood vessels endothelium (lectin Ulex europeus and Factor VIII) and myelin basic protein (MBP) was used. A distinct F VIII immunoreactivity of vessels endothelium was recorded since a 1 day old newborn. Lectin immunoreactivity suggested the increased vascularization of the undergoing myelination spinal cord tracts. In the postnatal period, which was characterized morphologically by the nearly completed myelination, the spinal white matter appeared poorly vascularized. A temporary increase of spinal cord tract vascularization during myelination is probably caused by local secretion of angiogenic factors. It is possible that their source might be young developing myelin.

Animals↗

PubMed1994

Immunohistochemical determination of in vivo distribution of Bax, a dominant inhibitor of Bcl-2.

The protein encoded by the bcl-2 gene is a regulator of programmed cell death and apoptosis. The cell survival-promoting activity of this protein is opposed by Bax, a homologous protein that forms heterodimers with Bcl-2 and accelerates rates of cell death. In this report, the in vivo patterns of bax gene expression were immunohistochemically assessed in the mouse, with a polyclonal antibody raised against a synthetic peptide corresponding to a unique region in the murine Bax protein. Direct comparisons were made with Bcl-2 by using anti-peptide antisera specific for the mouse Bcl-2 protein. The expression of bax was more widespread than bcl-2. For example, Bax immunoreactivity was present in the hepatocytes of the liver, the exocrine pancreas, and the renal tubule epithelial cells whereas Bcl-2 was absent from these tissues. Both the Bax and Bcl-2 proteins were present in several epithelia examined, including the small intestines, colon, breast, prostate, respiratory tract, and skin. The most intense Bax immunostaining was seen in cells located in the base of the crypts of the small intestinal mucosa, consistent with reports of high rates of spontaneous and inducible apoptosis in this region. Bcl-2 immunostaining was completely absent from these cells but was present in the absorptive epithelial cells of the small intestine. In contrast, Bax immunostaining in the colon tended to be stronger in the surface epithelial cells that had advanced up the crypts towards the lumen and that are destined for programmed cell death, whereas Bcl-2 immunoreactivity generally was stronger in the base of the colonic crypts. Similarly, bax expression in the gastric pits of the stomach occurred in a gradient such that higher levels of Bax immunostaining were found in the upper layers of gastric glands than in the lower regions. In addition, strong Bax immunostaining was detected in the androgen-dependent secretory epithelial cells of the prostate, whereas Bcl-2 was limited to the androgen-independent basal cells. Like Bcl-2, Bax was found in the thymic medulla but not the cortex, despite the propensity for immature cortical thymocytes to undergo apoptosis. Unlike Bcl-2, however, Bax immunostaining tended to be more intense in the germinal center lymphocytes of lymph nodes than in the interfollicular lymphocytes, consistent with the high rate of apoptotic cell death in the former.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1994

Apoptosis regulation by interaction of Bcl-2 protein and Raf-1 kinase.

The Bcl-2 protein is over-produced in many types of human tumors and suppresses apoptosis induced by a wide-variety of stimuli, including chemotherapeutic drugs and gamma-irradiation. The biochemical mechanism of action of the Bcl-2 protein however remains enigmatic. Here we show that Bcl-2 can be co-immunoprecipitated with the serine/threonine-specific Raf-1 kinase both in a mammalian hemopoietic cell 32D.3 and when the two proteins are produced in Sf9 insect cells using recombinant baculoviruses. Though analysis of Raf-1 deletion mutants suggested that the C-terminal half of the protein which contains the catalytic domain is sufficient for co-immunoprecipitation with Bcl-2, Raf-1 does not appear to induce phosphorylation of Bcl-2 protein in 32D.3 and Sf9 cells. Furthermore, a mutant form of Raf-1 that lacks kinase activity could still be co-immunoprecipitated with Bcl-2 in Sf9 cells, suggesting that the interaction of these proteins does not reflect a kinase-substrate relation. Gene transfer experiments using 32D.3 hemopoietic cells demonstrated functional synergy between Bcl-2 and Raf-1 with regards to suppression of apoptosis induced by growth factor withdrawal. Taken together, these observations for the first time functionally link Bcl-2 to a signal transducing protein and suggest that the interaction of the Bcl-2 and Raf-1 proteins may be responsible for their ability to cooperate in the suppression of apoptosis.

Animals↗

PubMed1994

Immunohistochemical analysis of Mcl-1 and Bcl-2 proteins in normal and neoplastic lymph nodes.

The Bcl-2 protein blocks programmed cell death and becomes overproduced in many follicular non-Hodgkin's lymphomas as the result of t(14; 18) translocations involving the Bcl-2 gene. Mcl-1 is a recently discovered gene whose encoded protein has significant homology with Bcl-2 but whose function remains unknown. In this study, we compared the in vivo patterns of Bcl-2 and Mcl-1 protein production in normal and neoplastic lymph node biopsies by immunohistochemical means using specific polyclonal antisera. Intracellular Mcl-1 immunoreactivity was located primarily in the cytosol in a punctate pattern and was also seen in association with the nuclear envelope in many cases, similar to the results obtained for Bcl-2, which resides in the outer mitochondrial membrane, nuclear envelope, and endoplasmic reticulum. In 4 of 4 reactive tonsils and 28 of 28 nodes with reactive follicular hyperplasia, reciprocal patterns of Bcl-2 and Mcl-1 protein expression were observed. Bcl-2 immunostaining was highest in mantle zone lymphocytes and absent from most germinal center cells, whereas Mcl-1 immunoreactivity was highest in germinal center lymphocytes and absent from mantle zone lymphocytes. Mcl-1 was also expressed in some interfollicular lymphocytes, particularly those that had the appearance of activated lymphocytes. Similar to the patterns of Bcl-2 and mcl-1 expression seen in reactive nodes, Mcl-1 protein was largely absent from the malignant cells in 2 of 2 mantle cell lymphomas, whereas strong Bcl-2 immunostaining was found in these cells. In contrast to normal nodes, however, the neoplastic follicles of t(14;18) containing follicular non-Hodgkin's lymphomas immunostained positively for both Bcl-2 and Mcl-1 in 24 of 27 cases. Intense immunostaining for Mcl-1 was also observed in Reed-Sternberg cells in 2 of 2 cases of Hodgkin's disease but Bcl-2 immunoreactivity was present at much lower levels. These findings demonstrate that the levels of Mcl-1 and Bcl-2 proteins are differentially regulated in normal and neoplastic cells in lymph nodes and thus suggest different roles for these proteins in the control of cell life and death in these tissues.

Amino Acid Sequence↗

PubMed1994

Immediate early up-regulation of bax expression by p53 but not TGF beta 1: a paradigm for distinct apoptotic pathways.

Recently, both Bcl-2, which promotes cell survival, and Bax, which promotes cell death, have been implicated as major players in the control of apoptotic pathways, and it has been suggested that the ratio of Bcl-2 and Bax protein controls the relative susceptibility of cells to death stimuli. We have used M1 myeloid leukemia cells and genetically engineered M1 variants as a model system to study apoptosis induced by two distinct apoptotic stimuli. This includes apoptosis induced by activation of wild type p53 function of a temperature sensitive p53 transgene expressed in M1 cells, which do not express endogenous p53, and apoptosis induced by TGF beta 1. It is shown that the kinetics of apoptosis induced by p53 is more rapid than apoptosis induced by TGF beta 1. It is also shown that ectopic expression of Bcl-2, at levels which blocked TGF beta 1-induced apoptosis of M1 cells, delayed, but did not block, p53-induced apoptosis. Both p53 and TGF beta 1 down-regulated endogenous Bcl-2 expression, but only p53 up-regulated Bax expression, where bax has been identified as a p53 immediate early response gene. Thus, the p53-mediated up-regulation of Bax may provide at least a partial explanation for the more rapid rate of apoptosis induced by p53 compared to by TGF beta 1, as well as for the ineffectiveness of ectopoic Bcl-2 to abrogate p53-mediated apoptosis. These findings provide first insights to the molecular mechanisms which mediate p53-induced apoptosis, identifying bax and bcl-2 as p53 regulated genes, and serve as a paradigm of how the intracellular balance of Bcl-2 to Bax is differentially altered by distinct death stimuli.

Apoptosis↗

PubMed1994

Tumor suppressor p53 is a regulator of bcl-2 and bax gene expression in vitro and in vivo.

The p53 tumor suppressor gene product can induce apoptotic cell death through an unknown mechanism. Here we demonstrate that a temperature-sensitive p53 induces temperature-dependent decreases in the expression of the apoptosis-suppressing gene bcl-2 in the murine leukemia cell M1, while simultaneously stimulating increases in the expression of bax, a gene which encodes a dominant-inhibitor of the Bcl-2 protein. Mice deficient in p53 exhibit increases in Bcl-2 and decreases in Bax protein levels in several tissues as determined by immunohistochemical and immunoblot methods. The findings suggest a potential mechanism by which p53 regulates apoptosis, as well as responses to radiation and chemotherapeutic drugs in cancer.

Animals↗

PubMed1993

BCL-2 prevents killing of neuronal cells by glutamate but not by amyloid beta protein.

The 26-kDa protein encoded by the bcl-2 gene is a regulator of cell survival and blocks cell death induced by numerous stimuli. Amyloid beta protein (ABP) and glutamate are believed to play important roles in the neuronal cell death that occurs in Alzheimer's disease and stroke, respectively. Glutamate induces apoptosis in some neuronal cell systems, but it remains controversial whether ABP-mediated cell death occurs through apoptosis or necrosis. To further explore the pathways for cell death that are activated by these neurotoxins, we examined the effects of elevated levels of the p26-Bcl-2 protein on the susceptibility of neuronal cell lines to killing by glutamate and ABP. Gene transfer methods were used to elevate p26-Bcl-2 protein levels in the rat nerve lines PC-12 and B50 and the human neuroblastoma IMR-5. Bcl-2 protected all 3 cell lines from glutamate induced cell death but had no effect on killing mediated by ABP.

Amyloid beta-Peptides↗

PubMed1993

Regulation of Bcl-2 oncoprotein levels with differentiation of human neuroblastoma cells.

When established in culture, human neuroblastoma cell lines typically are comprised of heterogeneous cellular subpopulations, including neuroblastic (N-type), substrate-adherent (S-type), and intermediate (I-type) cells that can be distinguished by their characteristic morphologies and expression of differentiation-associated antigens. Here we examined the relative levels of the Bcl-2 oncoprotein in 15 clones derived from four different neuroblastoma cell lines. Among six clones isolated from the SK-N-SH line, levels of p26-Bcl-2 correlated with morphology and differentiation markers with the hierarchy of bcl-2 expression being: N-type cells > N/I-type > I-type > S-type. Furthermore, stimulation of one of the N-type clones, SH-SY5Y, with the phorbol ester, 12-O-tetradecanoylphorbol-13-acetate, induced differentiation toward a more neuronal-like phenotype and resulted in a 5- to 10-fold elevation in the relative levels of Bcl-2 protein. High relative amounts of p26-Bcl-2 protein were also found in an N-type clone derived from the SMS-KCN line. In two N-type clones derived from the LA-N-1 line, however, levels of Bcl-2 protein were only moderately elevated, and in one N-type clone from the SK-N-BE(2) line the levels of Bcl-2 protein were low. Thus, high relative levels of Bcl-2 oncoprotein are not a universal feature of N-type cells (three of six clones tested). In contrast, all 5 of the S-type clones evaluated contained relatively low levels of Bcl-2 protein, suggesting that these cells (which may represent embryonic precursors of Schwann, glial, and melanocytic cells) do not typically express the bcl-2 gene at high levels. Consistent with this inverse correlation between Bcl-2 protein levels and S-type characteristics, stimulation of an I-type clone derived from the SK-N-BE(2) line with 5-bromodeoxyuridine was accompanied by an accumulation of S-type cells in these cultures, decreased Bcl-2 protein, diminutions in the neuronal markers neurofilament-M and neuron-specific enolase, and an increase in the relative levels of the S-type marker proteins vimentin and beta-2-microglobulin. Conversely, stimulation of this I-type clone with retinoic acid resulted in an accumulation of N-type cells (which are thought to represent embryonic precursors of sympathetic neurons), decreased vimentin and beta-2-microglobulin, increased neurofilament-M, and a marked elevation in p26-Bcl-2.(ABSTRACT TRUNCATED AT 400 WORDS)

Antineoplastic Agents↗

PubMed1993

Investigation of the subcellular distribution of the bcl-2 oncoprotein: residence in the nuclear envelope, endoplasmic reticulum, and outer mitochondrial membranes.

A multidisciplinary approach was taken to investigate the intracellular locations of the 26-kDa integral membrane protein encoded by the bcl-2 gene. Subcellular fractionation analysis of a t(14;18)-containing lymphoma cell line revealed the presence of Bcl-2 protein in nuclear, heavy-membrane, and light-membrane fractions but not in cytosol. Sedimentation of heavy-membrane fractions in Nycodenz and Percoll continuous gradients demonstrated comigration of p26-Bcl-2 with mitochondrial but not other organelle-associated proteins. Fractionation of light-membrane fractions using discontinuous sucrose-gradients revealed association of Bcl-2 protein primarily with lighter-density microsomes (smooth endoplasmic reticulum) as opposed to heavy-density microsomes (rough endoplasmic reticulum). Immune microscopy studies using laser-scanning microscopy, pre- and postembedding electron microscopic methods, and six different anti-Bcl-2 antibodies demonstrated Bcl-2 immunoreactivity in the nuclear envelope and outer mitochondrial membrane in a patchy distribution. Furthermore, anti-Bcl-2 antibody immunoreactivity generally appeared to directly overlie the nuclear envelope in high magnification electron microscopic studies, reminiscent of nuclear pore complexes. Addition of in vitro translated p26-Bcl-2 to isolated translocation-competent mitochondria revealed transmembrane domain-dependent association of Bcl-2 protein with mitochondria but provided no evidence for import into a protease-resistant compartment, consistent with immunomicroscopic localization to the outer mitochondrial membrane. Taken together, the findings demonstrate that p26-Bcl-2 resides primarily in the nuclear envelope, endoplasmic reticulum, and outer mitochondrial membrane in a nonuniform distribution suggestive of participation in protein complexes perhaps involved in some aspect of transport.

Cell Fractionation↗

PubMed1992

The breakdown process of human brain infarction in middle-aged and senile cases.

The material comprised 15 cases of ischemic brain stroke at the age of 45 to 101 years. Six brain of subjects deceased at the age of 45 to 57 years and 9 brains of those deceased at the age of 80 to 101 years were studied. Phagocytic cell immunoreactivity in both age groups during the first 5 days and on the 11th and 12th were compared. Phagocytic reactivity in cases of patients who died on the 6th, 15th and 35th days after stroke onset was also estimated. Colliquative necrosis with cavitation was observed in middle-aged cases from the 3rd infarction day. In the senile group the beginning of tissue breakdown was noted on the 5th day, but colliquative necrosis with cavitation was found on the 11th infarction day. Senile alterations in the biochemical components in various brain tissue elements are probably the cause of the different course and dynamics of the pathological process.

Aged↗

PubMed1992

Does damage of perivascular astrocytes in multiple sclerosis plaques participate in blood-brain barrier permeability?

In six young and two senile MS cases perivascular astrocytes within demyelination lesions were evaluated immunocytochemically. The peroxidase-antiperoxidase method of Sternberger et al. (1970) was used for visualization of glial fibrillary acidic protein (GFAP). In all cases very weak immunoreactivity of perivascular astrocytes was noted. Accumulation of perivascular glial fibers, and infrequently their fragmentation were observed both within active and old demyelination plaques. Clasmatodendrosis, Rosenthal's fibers and prominent regressive changes of astrocyte perikarya were found only in old plaques. A lack of immunoreactivity of perivascular astrocytes was noted within old demyelination lesions. The background of the latter was often immunonegative to GFAP. It is suggested that secondary damage of perivascular astrocytes influences vascular permeability within demyelination lesions including old plaques.

Adult↗