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A da Cunha

Publications and source records attributed to A da Cunha.

At least 19 recordsLinked to original sources
PubMed2001

The effect of therapeutic ultrasound on repair of the achilles tendon (tendo calcaneus) of the rat.

The purpose of this study was to evaluate the effects of therapeutic ultrasound (US) on the healing process in the Achilles tendon (Tendo calcaneus) of Wistar rats after tenotomy. Sonication was performed at a frequency of 1 MHz, an intensity of 0.5 W/cm(2) (SATA), for 5 min, over a period of 14 consecutive days in two modalities (n = 15); in both continuous and pulsed modes. The control group was divided into tenotomized, mock-sonicated and nontenotomized tendons (n = 15). On the 15th postoperative day, the tendons were removed and analyzed by using the polarized light microscopy, with the purpose of detecting and measuring the organization of collagen fibers through birefringence. The results showed a high birefringence for the tendons treated using the pulsed mode (p < 0.001), revealing the best organization and aggregation of collagen bundles. Sonication in the continuous mode induced a decrease (p = 0.047) in the ability to quicken the healing process. These findings suggest that US therapy is beneficial in the early healing process of tendons when the pulsed mode is used.

Achilles Tendon↗
PubMed1997

Transforming growth factor-beta1 in adult human microglia and its stimulated production by interleukin-1.

Ameboid microglia express human immunodeficiency virus 1 (HIV-1) more frequently than do ramified microglia. These two microglial subtypes might also differ in the frequency with which they express transforming growth factor-beta1 (TGF-beta1), a cytokine that regulates HIV-1 expression in monocytes. Results described here show that ameboid and ramified microglia express TGF-beta1. In brain tissues from HIV-1-infected individuals as compared with seronegative controls, ameboid rather than ramified microglia more frequently expressed TGF-beta1. Ameboid microglia, isolated and cultured from postmortem adult human brain more frequently expressed TGF-beta1 in presence of interleukin-1(IL-1), a cytokine that is elevated in brains of HIV-1-infected individuals when compared with seronegative controls. The stimulation of TGF-beta1 by IL-1 was dose and time dependent, occurring with ameboid microglia isolated from either frontal cortex or globus pallidus but not midbrain pons. Ameboid microglia are similar to the RCA-1-positive cells that form clusters, called microglial nodules, in the brain of HIV-1-infected individuals. Pathologic conditions, such as disseminated microglial nodules, are associated with HIV-1 encephalitis, direct infection of the brain, and moderate to severe neurologic impairment. TGF-beta1 expression in ameboid microglia may play a role in HIV-1 neuropathogenesis.

Acquired Immunodeficiency Syndrome↗
PubMed1997

A neuronal and neuroanatomical correlate of HIV-1 encephalopathy relative to HIV-1 encephalitis in HIV-1-infected children.

Progressive central nervous system dysfunction analogous to the AIDS dementia complex (ADC) seen in adults (HIV-1-associated progressive encephalopathy or HIV-1 encephalopathy) commonly occurs in HIV-1-infected children. The cause appears to be directly or indirectly related to HIV-1, rather than to other opportunistic pathogens. The exact mechanism(s) by which the virus affects brain function is not known. To determine whether the virus might modify brain function via an alteration in cortical neurons, we examined peptide neurotransmitter expression in the frontal cortex of HIV-1-infected cases with clinical HIV-1 encephalopathy relative to pathologic HIV-1 encephalitis. In situ hybridization was used to determine the level of peptide neurotransmitter expression of somatostatin in the frontal cortex of cases with and without HIV-1 encephalopathy and/or HIV-1 encephalitis. A 2-fold higher number of preprosomatostatin mRNA-positive interneurons was present in layer IV of cases with HIV-1 encephalitis compared with cases without HIV-1 encephalitis. In cases with PE, this neuronal alteration was 4- to 5-fold higher than in cases without PE, and was present in subcortical white matter in addition to layer IV. In cases having both PE and HIV-1 encephalitis, and in cases with HIV-1 encephalitis alone, these neuronal alterations in layer IV and/or subcortical white matter related to disseminated microglial nodules, even when these potentially viral-infected cells were negative for HIV-1 p24 antigen, a marker of productive viral infection. An alteration in preprosomatostatin mRNA-expressing cells occurring with HIV-1 encephalitis may be at least one mechanism that contributes to HIV-1 encephalopathy. When compared with other cortical laminae, layer IV receives most of its synaptic input from the mediodorsal nucleus of the thalamus. Neurons in the subcortical white matter project to the thalamus. The thalamus has been shown to have high amounts of viral antigen and increased metabolic activity in patients with AIDS. An alteration in preprosomatostatin mRNA-expressing cells may play a role in HIV-1 encephalopathy.

AIDS Dementia Complex↗
PubMed1995

Distinct expressions of three cytokines by IL-1-stimulated astrocytes in vitro and in AIDS brain.

Interleukin-1 (IL-1) is elevated in brain tissue of individuals who died with acquired immunodeficiency syndrome (AIDS) and other diseases where this cytokine likely stimulates reactive astrocytosis. IL-1 stimulates, among others, production of interleukin-6 (IL-6), granulocyte macrophage colony-stimulating factor (GM-CSF), and tumor necrosis factor-alpha (TNF-alpha) in cultured astrocytes and astrocytoma cell lines. These and other cytokines may contribute to the neuropathogenesis after infection by human immunodeficiency virus type-1 (HIV-1). For example, concentration of TNF-alpha is increased in brain tissue of individuals who died with AIDS and correlates with the severity of AIDS Dementia Complex (ADC). TNF-alpha and IL-6 have been immunocytochemically detected in brain tissue but they have not been localized to astrocytes. We, therefore, examined the expression of IL-6, GM-CSF, and TNF-alpha in human primary astrocytes and astrocytoma cell lines U251 and 253 exposed to IL-1 in serum-free medium. In addition, we immunocytochemically assayed GM-CSF expression by astrocytes in brain tissue (n = 8). The three cytokines were differentially induced in cultured astrocytes by IL-1. The astrocytoma cell lines recapitulated cytokine-specific patterns of expression in astrocytes. The patterns were characterized by amounts produced, compartmentalization (intra- and/or extracellular), time courses, and optimal doses of IL-1 for induction. GM-SCF-like immunoreactivity was detected in some but not all, GFAP+ cells. GM-CSF+/GFAP+ cells were detected in only three of seven cases containing GM-CSF immunoreactivity. Thus, a discrepancy may exist between human astrocytic cytokine expression in vitro and in tissue. Novel methods therefore may need to be developed to recapitulate in vitro the heterogeneity of astrocytic cytokine expression in AIDS and other brain tissue.

AIDS Dementia Complex↗
PubMed1995

HIV-1 non-specifically stimulates production of transforming growth factor-beta 1 transfer in primary astrocytes.

HIV-1 expression in monocytes/macrophages can be controlled by transforming growth factor-beta 1 (TGF-beta 1). TGF-beta 1 is present in astrocytes surrounding HIV-1-infected monocyte/macrophages in brain tissue from patients with AIDS but not from seronegative, normal individuals. We sought to determine whether or not production of TGF-beta 1 can be directly stimulated by HIV-1 in astrocytes. Astrocytes from neonatal rat cortex grown in primary culture were exposed to HIV-1 virions for 24 h. One day later, TGF-beta 1 was measured in culture supernatants by a biological assay. HIV-1 caused 1.7-2.1-fold increase in extracellular concentration of TGF-beta 1. TGF beta 1 production also was stimulated by recombinant HIV-1 proteins gp120, p66 and p24. Gp120 labeled with fluorescein was visualized inside astrocytes and its stimulatory effect was not blocked by antibodies against rat CD4. The effect was not specific to HIV-1 and its proteins, because non-opsonized Latex particles and leucine methyl ester (LME) (known to be phagocytosed and endocytosed, respectively, by astrocytes) also stimulated TGF-beta 1 production. The effect was inhibited by two inhibitors of the phago/endocytotic pathway, chloroquine and leupeptin. These results may be relevant to the neuropathogenesis of HIV-1 infection.

Animals↗
PubMed1994

Neuronal substrates for SIV encephalopathy.

Prior to the onset of immunodeficiency disease, neurochemical and neuropathological events associated with motor and/or cognitive impairment can be identified in rhesus monkeys infected with simian immunodeficiency virus (SIV). These are astrocytosis, up-regulation of mRNA encoding the neuropeptide somatostatin (SRIF) and an increased expression of MHC Class II antigen. End-stage immunodeficiency disease has been associated with robust viral expression in the CNS frequently observed as multinucleated giant cell formation. SIV encephalitis has not been observed in animals whose only clinical signs of SIV disease were motor and/or cognitive impairment. These data suggest that neuronal dysfunction discernable as altered neuropeptide expression in cortical neurons precedes frank structural damage to the CNS in SIV encephalopathy. This model is consistent with the mechanism of neuropathogenesis in human HIV encephalopathy that can be partially inferred from neurochemical and neuropathological examination of autopsy material in HIV disease.

Animals↗
PubMed1993

Control of astrocytosis by interleukin-1 and transforming growth factor-beta 1 in human brain.

Astrocytosis is a common neurocellular manifestation of brain pathology in individuals with a variety of diseases. It is comprised of astrocytic hyperplasia (an increase in number of astrocytes) and astrocytic hypertrophy (an increase in size of astrocytes). The precise cause(s) of astrocytosis remains unknown. We morphometrically measured the relative extent of astrocytosis in brains of 22 individuals who died with seven different diseases. The relative amounts of interleukin-1 (IL-1) and transforming growth factor-beta 1 (TGF-beta 1) immunoreactive products (IRPs) were next assessed in sections serial to those in which astrocytosis was measured because these cytokines were shown in animal and in vitro experiments to be associated with astrocytosis. The data demonstrate that astrocytosis and these cytokines were co-localized in all examined human tissues. Relative increase in density of astrocytes was correlated with the increase in total IL-1 but not TGF-beta 1. In contrast, the increase in size of astrocytes was correlated with TGF-beta 1 associated only with astrocytes but not with total IL-1. Both IL-1 and TGF-beta 1 IRPs were present in GFAP IRP-containing and other cells, as assessed by double label immunocytochemistry. These observations suggest that IL-1 acts on astrocytes by both, paracrine and autocrine mechanisms whereas, TGF-beta 1 only acts by an autocrine mechanism. Because these correlations were statistically significant and also because a change in number and size of astrocytes constitutes the most frequent response of astrocytes to several diseases or injury, we conclude that these cytokines may mediate the most common pathological change in human brain.

Astrocytes↗
PubMed1993

Gliosis in human brain: relationship to size but not other properties of astrocytes.

Gliosis is the most frequent and therefore important neurocellular reaction to brain insult occurring in diseases ranging from AIDS to infarction. Neuropathological diagnosis of gliosis is based on morphological changes of brain glial cells. Changes commonly agreed to reflect gliosis are qualitative increases in size, number and glial fibrillary acidic protein (GFAP) immunoreactivity of astrocytes. These parameters were morphometrically quantified in brain tissues of 22 individuals who died with 7 diseases and statistically compared to the extent of gliosis independently determined by 3 qualified observers. The data indicate that the extent of gliosis correlated with the increase in size of astrocytes in white matter (p = 0.67) and this relationship was statistically significant (P = 0.0006). In contrast, the extent of gliosis was not correlated with the density of astrocytes nor the intensity of GFAP staining.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Glial cell-specific mechanisms of TGF-beta 1 induction by IL-1 in cerebral cortex.

Transforming growth factor beta-1 (TGF-beta 1) immunoreactive product (IRP) has recently been detected in autopsied brains of individuals who died with central nervous system diseases and/or fever but not in normal individuals or in normal rodent brain. However, the mechanism(s) of induction of TGF-beta 1 in brain and the identity of cells expressing TGF-beta 1 need to be understood before a role, if any, for this potent pleiotropic cytokine in neuropathogenesis can be discerned. Towards this end we determined that IL-1 stimulated the production of TGF-beta 1 IRP in cells and TGF-beta 1 activity in culture fluids of all glial cells, astrocytes, microglial cells, and oligodendrocytes, derived from neonatal rat cortex and grown in cell type-enriched cultures. TGF-beta 1 production in vitro varied with the cell type and isoform of IL-1. Oligodendrocytes produced the most and astrocytes the least amount of TGF-beta 1. IL-1 alpha stimulated TGF-beta 1 production in all glial cell types, whereas IL-1 beta did not. In vivo, TGF-beta 1 IRP was detected in human tissues from cerebral frontal cortex and subcortical white matter only when interleukin-1 (IL-1) was elevated in the same tissues. Moreover, the amount of detectable TGF-beta 1 was positively correlated with the amount of detectable IL-1 (rho = 0.605; P = 0.003), as determined by morphometry. Double-labelling of cells for their phenotypic markers and expression of TGF-beta 1 indicated that all glial cells, but not neurons, expressed TGF-beta 1. IL-1 alpha and IL-1 beta IRPs were also detected in all three glial cell types, most frequently in astrocytes and least frequently in microglial cells. The cells containing both cytokine IRPs were also detected. These results indicate that TGF-beta 1 may be induced by IL-1 in all glial cells of the frontal cortex, by both autocrine and paracrine mechanisms.

Animals↗
PubMed1992

Transforming growth factor-beta 1 (TGF-beta 1) expression and regulation in rat cortical astrocytes.

Transforming growth factor-beta 1 (TGF-beta 1) is a potent modulator of immune and glial cells' functions and thus, could play an important role in neuro-immune interaction. However, published reports disagree on whether or not TGF-beta 1 is expressed in normal brain. We demonstrate here the constitutive expression of TGF-beta 1 mRNA but not protein in both cerebral cortex and primary rat cortical astrocytes. Steady-state TGF-beta 1 mRNA level increased 2-fold in adult compared to neonatal cortex and during proliferation and differentiation of astrocytes in primary culture. This response was not accompanied by the appearance of detectable TGF-beta protein either in vivo or in vitro. However, both intracellular immunoreactive TGF-beta and extracellular TGF-beta 1 activity were detected upon in vitro stimulation of astrocytes with interleukin-1 (IL-1). The extracellular TGF-beta 1 increased with time of exposure to and concentration of IL-1. In contrast, the amount of TGF-beta 1 mRNA remained unchanged during stimulation of astrocytes with IL-1. These results suggest that the production of TGF-beta 1 in astrocytes is regulated at both mRNA and protein levels. The former may occur during astrocytic development, and the latter during astrocytic response to injury in association with elevation of IL-1.

Age Factors↗
PubMed1991

Developmental regulation of GAP-43, glutamine synthetase and beta-actin mRNA in rat cortical astrocytes.

Steady-state levels of mRNA encoding growth-associated protein 43 (GAP-43), glutamine synthetase (GS) and beta-actin were measured during development of neonatal rat cortical astrocytes in primary culture. GAP-43 mRNA and protein decreased rapidly during the first 2 weeks and slowly thereafter. In contrast, GS mRNA increased approximately 3-fold during the first 2 weeks and reached maximum by day 15. Actin mRNA first increased up to 8 days and decreased thereafter reaching a constant amount of 15 days, similar to the initial low value. Thus, GAP-43, GS and beta-actin mRNA levels are differentially regulated during development of astrocytes in primary culture. Because the patterns of expression of astrocytic markers GS and GFAP (shown previously) in vitro and in vivo are similar to each other, primary cultures of astrocytes may be an excellent system for investigating mechanisms of developmental regulation of these genes.

Actins↗
PubMed1990

Regulation of immunoreactive GAP-43 expression in rat cortical macroglia is cell type specific.

Growth-associated protein 43 (GAP-43) is an abundant, intensely investigated membrane phosphoprotein of the nervous system (Benowitz, L.I., and A. Routtenberg. 1987. Trends Neurosci. 10:527-532; Skene, J. H. P. 1989. Annu. Rev. Neurosci. 12:127-156), with a hitherto unknown function. We have previously demonstrated that astrocytes, brain macroglial cells, contain GAP-43 (Steisslinger, H. W., V. J. Aloyo, and L. Vitković, 1987. Brain Res. 415:375-379; Vitković, L., H. W. Steisslinger, V. J. Aloyo, and M. Mersel. 1988. Proc. Natl. Acad. Sci. USA. 85:8296-8300; Vitković L., and M. Mersel. 1989. Metab. Brain Dis. 4:47-53). Results from double immunofluorescent labeling experiments presented here show that oligodendrocytes also contain GAP-43 immunoreactivity (GAP-43ir). Thus, all three macroglial cell types of the central nervous system (type I and type 2 astrocytes and oligodendrocytes) contain GAP-43. Whereas immunoreactive GAP-43 is expressed by progenitors of all macroglial cell types, the developmental regulation of its expression is cell type specific. Immunoreactive GAP-43 is downregulated in type 1 astrocytes, and constitutively expressed in both type 2 astrocytes and oligodendrocytes. These results may be relevant to potential function(s) of GAP-43.

Animals↗
PubMed1988

Purification, characterization and induction of L-phenylalanine ammonia-lyase in Phaseolus vulgaris.

The enzyme L-phenylalanine ammonia-lyase was purified from leaves of Phaseolus vulgaris by Sephacryl S-200 gel filtration and Sepharose-4-B--succinyl-aminoethyl-L-phenylalanine affinity chromatography. L-Phenylalanine ammonia-lyase was specifically eluted from the affinity matrix with its substrate L-phenylalanine at 20-25 degrees C. The purified enzyme was shown to be homogeneous by gel electrophoresis both in presence and absence of SDS. Its Mr, determined by gel filtration and non-denaturing gel electrophoresis, was 320,000 +/- 9000 and 330,000 +/- 4000 respectively. After SDS electrophoresis only one band of Mr 83,000 +/- 4000 was detected, indicating that the enzyme is an oligomer containing four subunits. The pH optimum of enzyme activity was 8.8-9.2. Ampholyte isoelectrofocusing in polyacrylamide demonstrated the presence of a single charged species at pH 4.2. The homogeneous enzyme catalyzed the deamination of L-phenylalanine to trans-cinnamate but did not catalyze the transamination of L-phenylalanine to L-phenylpyruvate. The enzyme showed Km 1.25 mM for L-phenylalanine. Antibodies to homogeneous L-phenylalanine ammonia-lyase recognised specific epitopes on L-phenylalanine aminotransferase as demonstrated by immunoaffinity purification and immunoblotting. The induction of L-phenylalanine ammonia-lyase activity during phaseollin biosynthesis in the Phaseolus vulgaris--Colletotrichum lindemuthianum interaction was regulated by an increase in enzyme concentration resulting from an increase in de novo synthesis of L-phenylalanine ammonia-lyase protein.

Ammonia-Lyases↗