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Biomedical subjects

M Witte

Publications and source records attributed to M Witte.

At least 19 recordsLinked to original sources
PubMed1999

Cocaine enhances brain endothelial adhesion molecules and leukocyte migration.

Leukocyte infiltration of cerebral vessels in cocaine-associated vasculopathy suggests that cocaine may enhance leukocyte migration. We have investigated cocaine's effects on leukocyte adhesion in human brain microvascular endothelial cell (BMVEC) cultures and monocyte migration in an in vitro blood-brain barrier (BBB) model constructed with BMVEC and astrocytes. Cocaine (10(-5) to 10(-9) M) enhanced adhesion of monocytes and neutrophils to BMVEC. In the BBB model, cocaine (10(-4) to 10(-8) M) enhanced monocyte transmigration. Cocaine increased expression of endothelial adhesion molecules, intercellular adhesion molecule-1 (ICAM-1, CD54), vascular cell adhesion molecule-1 (VCAM-1), and endothelial leukocyte adhesion molecule-1 (ELAM-1) on BMVEC. The peak effect on ICAM-1 expression was between 6 and 18 h after treatment. ICAM-1 was increased by cocaine in BMVEC, but not in human umbilical vein endothelial cells, and the enhancement was greater in a coculture of BMVEC with monocytes. ICAM-1 expression was enhanced by a transcriptional mechanism. Polymyxin B inhibited up-regulation of adhesion molecules by LPS but not by cocaine. In LPS-activated BMVEC/monocyte coculture, cocaine increased secretion of tumor necrosis factor-alpha and interleukin-6. Taken together, these findings indicate that cocaine enhances leukocyte migration across the cerebral vessel wall, in particular under inflammatory conditions, but the effects are variable in different individuals. Cocaine's effects are exerted through a cascade of augmented expression of inflammatory cytokines and endothelial adhesion molecules. These could underlie the cerebrovascular complications of cocaine abuse.

Astrocytes↗
PubMed1999

[Standardized wound documentation of chronic wounds].

Owing to the long periods of treatment and multi-factoral etiology of chronic wounds, standardized wound documentation is necessary to enable judgement of the course of healing. We have developed a documentation system which permits a standardized assessment of chronic wounds by means of defined parameters and graded divisions. Besides containing the diagnostic and therapeutic measures which have been carried out, the documentation should also contain parameters of wound healing. These are the following: wound localisation, size of wound, degree of injury, infection, and wound morphology. Planimetry and photographic documentation complete the documentation. Thus a documented course of healing can be presented, which enables rapid retrospective analysis and, if needed, a change in therapeutic approach at an early stage. This complete, exact documentation is required by modern administration of justice and is a protection against the reversal of the onus of proof in lawsuits. The extent of documentation can be adapted to the individual needs of the institution responsible for treatment. However, a minimal amount of documentation should always include localisation of the wound, size, the diagnostic and therapeutic measures, and complications if any.

Chronic Disease↗
PubMed1999

[Temporary expression pattern in wound secretions and peripheral wound biopsies].

The local availability of growth factors and oxygen plays an important role in the healing of cutaneous lesions. We were able to quantify the ischemia in a standardized ischemic full-wall flap by measuring the ptiO2, and investigate the healing of defined wounds. The analysis of the immune histochemical section showed a significantly reduced expression of IGF-I in the wound edge of ischemic wounds. Simultaneously the rate of proliferation was reduced here. Probably the local chronic hypoxia leads to reduced IGF-I synthesis and thus to reduced proliferation and delayed wound healing. Further investigation is necessary to confirm this hypothesis. In a clinical study of wounds which had been treated with vacuum sealing we could establish no difference in the concentration of IGF-I in the wound fluid of seriously contaminated wounds in comparison to primary fasciotomy wounds. We therefore postulate a primary endocrinal secretion for IGF-I in cases of cutaneous wound healing; higher local consumption or reduced serum levels could stimulate the autocrinal local secretion of IGF-I. Further investigation is, however, needed in order to confirm this hypothesis.

Animals↗
PubMed1999

CXC and CC chemokine receptors on coronary and brain endothelia.

BACKGROUND: Chemokine receptors on leukocytes play a key role in inflammation and HIV-1 infection. Chemokine receptors on endothelia may serve an important role in HIV-1 tissue invasion and angiogenesis. MATERIALS AND METHODS: The expression of chemokine receptors in human brain microvascular endothelial cells (BMVEC) and coronary artery endothelial cells (CAEC) in vitro and cryostat sections of the heart tissue was determined by light and confocal microscopy and flow cytometry with monoclonal antibodies. Chemotaxis of endothelia by CC chemokines was evaluated in a transmigration assay. RESULTS: In BMVEC, the chemokine receptors CCR3 and CXCR4 showed the strongest expression. CXCR4 was localized by confocal microscopy to both the cytoplasm and the plasma membrane of BMVEC. In CAEC, CXCR4 demonstrated a strong expression with predominantly periplasmic localization. CCR5 expression was detected both in BMVEC and CAEC but at a lower level. Human umbilical cord endothelial cells (HUVEC) expressed strongly CXCR4 but only weakly CCR3 and CCR5. Two additional CC chemokines, CCR2A and CCR4, were detected in BMVEC and CAEC by immunostaining. Immunocytochemistry of the heart tissues with monoclonal antibodies revealed a high expression of CXCR4 and CCR2A and a low expression of CCR3 and CCR5 on coronary vessel endothelia. Coronary endothelia showed in vitro a strong chemotactic response to the CC chemokines RANTES, MIP-1alpha, and MIP-1beta. CONCLUSIONS: The endothelia isolated from the brain display strongly both the CCR3 and CXCR4 HIV-1 coreceptors, whereas the coronary endothelia express strongly only the CXCR4 coreceptor. CCR5 is expressed at a lower level in both endothelia. The differential display of CCR3 on the brain and coronary endothelia could be significant with respect to the differential susceptibility of the heart and the brain to HIV-1 invasion. In addition, CCR2A is strongly expressed in the heart endothelium. All of the above chemokine receptors could play a role in endothelial migration and repair.

Adult↗
PubMed1998

Constitutive and barbital-induced expression of the Cyp6a2 allele of a high producer strain of CYP6A2 in the genetic background of a low producer strain.

The levels of one or more cytochrome P450 (CYP) enzymes and the respective mRNAs are found to be higher in insecticide-resistant insects than in susceptible insects. To understand better how insects regulate the levels of CYPs, we examined the expression of the Cyp6a2 gene in various strains of Drosophila melanogaster. We also took a transgenic approach to understand the molecular mechanisms that are involved in strain variation of Cyp6a2 expression. RNA blot analysis showed that the constitutive expression of Cyp6a2 varies from strain to strain; the level of CYP6A2 mRNA is barely detectable in the underproducer ry506 strain, whereas it is very high in the overproducer 91-R and MHIII-D23 strains. The long terminal repeat (LTR) of mobile element 17.6 that is found in the 3' untranslated region (UTR) of the Cyp6a2 gene of some strains does not appear to have any role on the steady-state CYP6A2 mRNA level. We also found that the Cyp6a2 gene is inducible by barbital in 91-R, ry506 as well as 91-C, which carries an LTR insertion. To examine the genetic background of the underproducer ry506 strain with respect to Cyp6a2 expression, we transformed the ry506 strain with the Cyp6a2 allele of the overproducer 91-R strain (Cyp6a2-91 R) and measured the constitutive and barbital-induced expression of the Cyp6a2-91 R transgene in the transformed flies. The Cyp6a2-91 R transgene carrying 129 bp of DNA upstream of the ATG codon did not show any constitutive or barbital-induced expression in the ry506 host genome. However, transgenes with 1331 and 985 bp upstream DNA showed similar levels of constitutive expression that were higher than that of the endogenous Cyp6a2 gene of the ry506 host strain, but lower than the expression of the same gene in the 91-R strain. Both these transgenes, with 1331 and 985 bp upstream DNA, also showed induction with 0.1 M barbital. DNA sequence analysis revealed that in both 91-R and ry506, the upstream DNA between +1 and -985 bp contains a distal and a proximal group of three potential barbie boxes, i.e. cis-elements that are thought to be involved in barbiturate-mediated induction of CYP genes. Except for four bases located near the distal cluster of barbie boxes and two other bases, the base sequence of the upstream DNA is identical in ry506 and 91-R strains. These results suggest that the underproducer ry506 strain has the trans-regulatory factors to support constitutive and induced expression of the Cyp6a2-91 R allele carrying DNA between -129 and -1331 bp regions. Possible reasons for low constitutive expression of the endogenous Cyp6a2 gene and moderate level of expression of the Cyp6a2-91 R allele in the ry506 genetic background are discussed.

Alleles↗
PubMed1998

Scatter factor promotes motility of human glioma and neuromicrovascular endothelial cells.

Malignant gliomas are characterized by rapid growth, infiltration of normal brain tissue, and high levels of tumor-associated angiogenesis. The genetic and local environmental tissue factors responsible for the malignant progression from low to high grade gliomas and the highly malignant behavior of glioblastomas are not well understood. In a study of 77 human brain tissue extracts, high grade (III-IV) tumors had significantly greater scatter factor (SF) content than did low grade tumors or non-neoplastic tissue. To investigate the potential significance of SF accumulation in gliomas, we measured the effects of SF on DNA synthesis and motility of cultured human glioma cell lines. SF stimulated DNA synthesis in 7/10 glioma cell lines and in 3/3 neuromicrovascular endothelial cell (NMVEC) lines, consistent with our previous report that SF stimulated cell proliferation of a few human glioma cell lines. SF markedly stimulated the chemotactic migration of 10/10 glioma cell lines as well as 3/3 NMVEC lines. In addition, SF stimulated the 2-dimensional migration of glioma cells on culture surfaces coated with specific extracellular matrix molecules (collagen i.v., laminin, and fibronection). As expected based on these biologic responses to SF, 10/10 glioma lines and 4/4 NMVEC lines expressed mRNA for c-met, the SF receptor. To assess the possible in vivo significance of these migration assays, we compared the chemotactic response of a glioma cell line to human brain cyst fluids and tumor extracts that contained high or low SF concentrations. Fluids and extracts with high SF content tended to induce higher levels of chemotactic migration than did fluids and extracts with low SF content. Addition of anti-SF monoclonal antibody (MAb) inhibited migration induced by fluids and extracts with high SF content by about 30-50%.

Brain Neoplasms↗
PubMed1998

Cocaine enhances monocyte migration across the blood-brain barrier. Cocaine's connection to AIDS dementia and vasculitis?

Cocaine has wide-ranging effects on the immune and neuroendocrine systems (Fiala et al., 1996) resembling an inflammatory "stress" response with upregulation of pro-inflammatory cytokines and stimulation of the HPA axis (Gan et al., 1997). Cocaine abuse has also been associated with vascular pathology, including vasculitis, vasospasm and hemorrhage. These effects suggest that cocaine could perturb the function of endothelial cells, including the blood-brain barrier, and influence the progression to AIDS in HIV-infected individuals (Shapshak et al., 1997; Goodkin et al., 1997). In order to understand clinical consequences of cocaine abuse, it is important to gain insight into molecular and cellular basis of cocaine's effects on immune and endothelial cells. Cocaine's in vitro effects on (a) permeability, (b) immune cell migration, (c) adhesion molecules, and (d) cytokine expression were investigated in a blood-brain barrier model constructed with brain microvascular endothelial cells and fetal astrocytes with the following results: (a) cocaine and tumor necrosis factor-alpha (TNF-alpha) increased the model's permeability to inulin similarly in a dose-responsive fashion; (b) cocaine (10(-4) to 10(-8_ M) enhanced monocyte migration across the barrier with the maximum increase, approximately 100%, by 10(-5) M cocaine; (c) cocaine treatment also increased the expression of endothelial adhesion molecules, intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecules-1 (VCAM-1) and platelet/endothelial cell adhesion molecule-1 (PECAM-1); (d) although the cocaine in vitro effects on cytokine production by mononuclear cells have been difficult to assess due to a heterogeneity in the degree of responsiveness between individuals, the data suggest that mononuclear cells from cocaine addicts are sensitized to in vitro cocaine challenge with hypersecretion of inflammatory cytokines. Cocaine's in vivo manifestations are compatible with these in vitro effects: (A) chronic cocaine treatment of rats significantly increased rolling white blood cell flux, leukocyte-endothelium adhesion, and ICAM-1 expression in the mesentery (House et al., 1996); (B) cocaine injection to cocaine-dependent subjects tipped the balance of cytokine secretion by mononuclear cells to Th1-type (Gan et al., 1997), and (C) cocaine injection stimulated the hypothalamic-pituitary axis (HPA) to increase both anti- and pro-inflammatory hormonal secretion. Collectively, these results suggest that the immune effects of cocaine on endothelial, immune and neuroendocrine cells impair the function of the blood-brain, barrier, increase cell emigration from the blood vessels, in particular into the brain, and may cause vasculitis. These effects could also increase importation of HIV-1 into the brain.

AIDS Dementia Complex↗
PubMed1998

Verrucous carcinoma of the larynx.

Verrucous carcinoma is a well-differentiated squamous cell carcinoma with minimal cytologic atypia. Characteristically, the surface shows papillary fronds with prominent hyperkeratosis. Its benign appearance makes diagnosis difficult and often delays treatment. This is a review of 52 histologically confirmed cases of verrucous carcinoma of the larynx treated at the Mayo Clinic between 1960 and 1987. The follow-up ranged from 2 to 304 months. The most common primary treatment modality was surgery. Two patients died of laryngeal cancer. In both cases, the recurrence was a high-grade carcinoma histologically distinct from the original verrucous carcinoma. The T stage, clinical stage, and type of surgical excision failed to predict survival. The presence of extensive leukoplakia surrounding the exophytic tumor approached statistical significance (p = .08) in predicting recurrence. Four patients were treated with radiotherapy--in each, to control residual disease. One of these patients developed a local recurrence. None of the irradiated tumors in this series showed anaplastic dedifferentiation, and none of the irradiated patients died of uncontrolled local or regional disease. We conclude that verrucous carcinoma of the larynx should be treated by conservative surgical resection when possible. Radiotherapy can be effectively used for disease that cannot be resected with preservation of laryngeal function. Total laryngectomy should be reserved for recurrent disease or the rare case of anaplastic transformation.

Adult↗
PubMed1998

Inhibition of normal and experimental angiotumor endothelial cell proliferation and cell cycle progression by 2-methoxyestradiol.

With rapid growth and metabolism, aggressive cancers require an extensive vascular network, termed tumor angiogenesis. The body produces a variety of natural angiogenic inhibitors, among which is the mammalian estrogen metabolite, 2-methoxyestradiol (2-MeOE2). In this study, we compared the effects of 2-MeOE2 on a human umbilical vein cell line (HUVEC-C) and on an immortal, angiotumor-producing rat sinusoidal endothelial cell line (RSE-1). In vitro, the effects of varying concentrations of 2-MeOE2 from 0.01-100.0 microM were measured with cell counts and compared to control cells. HUVEC-C had an ED50 approximately 3.5 microM with approximately 27% inhibition of cell growth whereas RSE-1 had an ED50 approximately 2.2 microM with approximately 50% inhibition of cell growth compared with controls. The lowest concentration with maximal effect was 10.0 microM 2-MeOE2 for both cell lines. Using this concentration, flow cytometric analysis of cell cycles was performed with propidium iodide stained DNA of HUVEC-C and RSE-1 at 24 and 48 hr. Both demonstrated a significant (P < 0.0001) block at G2M of the cell cycle. At 48 hr, HUVEC-C had 32% of cells in G2M (control = 9% G2M), and RSE-1 had 36% of cells in G2M (control = 18% G2M). These findings demonstrate a strong in vitro antiproliferative effect of 2-MeOE2 on normal dividing endothelial as well as angiotumor cells mediated through a cell cycle-specific block at G2M. The antiendothelial, antiangiotumor effect of 2-MeOE2 supports its potential as a therapeutic agent against solid organ cancers, benign or malignant vascular growths, and other pathologic states dependent on angiogenesis.

2-Methoxyestradiol↗
PubMed1998

Amyloid-beta induces chemokine secretion and monocyte migration across a human blood--brain barrier model.

BACKGROUND: Aside from numerous parenchymal and vascular deposits of amyloid beta (A beta) peptide, neurofibrillary tangles, and neuronal and synaptic loss, the neuropathology of Alzheimer's disease is accompanied by a subtle and chronic inflammatory reaction that manifests itself as microglial activation. However, in Alzheimer's disease, alterations in the permeability of the blood-brain barrier and chemotaxis, in part mediated by chemokines and cytokines, may permit the recruitment and transendothelial passage of peripheral cells into the brain parenchyma. MATERIALS AND METHODS: Human monocytes from different donors were tested for their capacity to differentiate into macrophages and their ability to secrete cytokines and chemokines in the presence of A beta 1-42. A paradigm of the blood-brain barrier was constructed utilizing human brain endothelial and astroglial cells with the anatomical and physiological characteristics observed in vivo. This model was used to test the ability of monocytes/macrophages to transmigrate when challenged by A beta 1-42 on the brain side of the blood-brain barrier model. RESULTS: In cultures of peripheral monocytes, A beta 1-42 induced the secretion of proinflammatory cytokines TNF-alpha, IL-6, IL-1 beta, and IL-12, as well as CC chemokines MCP-1, MIP-1 alpha, and MIP-1 beta, and CXC chemokine IL-8 in a dose-related fashion. In the blood-brain barrier model, A beta 1-42 and monocytes on the brain side potentiated monocyte transmigration from the blood side to the brain side. A beta 1-42 stimulated differentiation of monocytes into adherent macrophages in a dose-related fashion. The magnitude of these proinflammatory effects of A beta 1-42 varied dramatically with monocytes from different donors. CONCLUSION: In some individuals, circulating monocytes/macrophages, when recruited by chemokines produced by activated microglia and macrophages, could add to the inflammatory destruction of the brain in Alzheimer's disease.

Alzheimer Disease↗
PubMed1997

A region of the beta subunit of the interferon alpha receptor different from box 1 interacts with Jak1 and is sufficient to activate the Jak-Stat pathway and induce an antiviral state.

Coexpression of the alpha and betaL subunits of the human interferon alpha (IFNalpha) receptor is required for the induction of an antiviral state by human IFNalpha. To explore the role of the different domains of the betaL subunit in IFNalpha signaling, we coexpressed wild-type alpha subunit and truncated forms of the betaL chain in L-929 cells. Our results demonstrated that the first 82 amino acids (AAs) (AAs 265-346) of the cytoplasmic domain of the betaL chain are sufficient to activate the Jak-Stat pathway and trigger an antiviral state after IFNalpha2 binding to the receptor. This region of the betaL chain, required for Jak1 binding and activation, contains the Box 1 motif that is important for the interaction of some cytokine receptors with Jak kinases. However, using glutathione S-transferase fusion proteins containing amino- and carboxyl-terminal deletions of the betaL cytoplasmic domain, we demonstrate that the main Jak1-binding region (corresponding to AAs 300-346 on the beta subunit) is distinct from the Box 1 domain (AAs 287-295).

Animals↗
PubMed1997

TNF-alpha opens a paracellular route for HIV-1 invasion across the blood-brain barrier.

BACKGROUND: HIV-1 invades the central nervous system early after infection when macrophage infiltration of the brain is low but myelin pallor is suggestive of blood-brain-barrier damage. High-level plasma viremia is a likely source of brain infection. To understand the invasion route, we investigated virus penetration across in vitro models with contrasting paracellular permeability subjected to TNF-alpha. MATERIALS AND METHODS: Blood-brain-barrier models constructed with human brain microvascular endothelial cells, fetal astrocytes, and collagen I or fibronectin matrix responded in a dose-related fashion to cytokines and ligands modulating paracellular permeability and cell migration. Virus penetration was measured by infectious and quantitative HIV-1 RNA assays. Barrier permeability was determined using inulin or dextran. RESULTS: Cell-free HIV-1 was retained by the blood-brain barrier with close to 100% efficiency. TNF-alpha increased virus penetration by a paracellular route in a dose-dependent manner proportionately to basal permeability. Brain endothelial cells were the main barrier to HIV-1. HIV-1 with monocytes attracted monocyte migration into the brain chamber. CONCLUSIONS: Early after the infection, the blood-brain barrier protects the brain from HIV-1. Immune mediators, such as TNF-alpha, open a paracellular route for the virus into the brain. The virus and viral proteins stimulate brain microglia and macrophages to attract monocytes into the brain. Infiltrating macrophages cause progression of HIV-1 encephalitis.

Astrocytes↗
PubMed1996

Scatter factor expression and regulation in human glial tumors.

Scatter factor (SF) (also known as hepatocyte growth factor [HGF]) is a cytokine that induces cell motility in vitro and angiogenesis in vivo. SF appears to be a determinant of the malignant phenotype in certain systemic cancers. We detected SF in extracts prepared from human gliomas, with the highest levels found in malignant tumors. Human glioblastoma cells expressed both SF and its receptor (c-met protein) in vivo, as demonstrated by immunohistochemistry. Consistent with these observations, we found moderate to high levels of production of immunoreactive and biologically active SF by cultured human glioblastoma cells (3 of 8 lines) and by neural microvascular endothelial cells (NMVEC) (3 of 3 lines). SF stimulated the proliferation of glioblastoma and NMVEC cell lines by paracrine or autocrine mechanisms. Conditioned medium (CM) from both glioblastoma and NMVEC cells contained SF-inducing factor (SF-IF) activity, defined by its ability to stimulate SF production in an indicator cell line (MRC5 human fibroblasts). This activity consisted of a high-molecular-weight (> 30 kDa), heat-sensitive component and a low-molecular weight (< 30 kDa), heat-stable component. Furthermore, glioblastoma CM stimulated NMVEC SF production, and NMVEC CM stimulated glioblastoma cell SF production, by 3- to 6-fold in each case. Our findings demonstrate that SF-dependent interactions between glioma cells, and between glioma cells and endothelium, can contribute to the heterogeneous proliferative and angiogenic phenotypes of malignant gliomas in vivo.

Brain↗
PubMed1996

Human herpesvirus 8 (Kaposi's sarcoma-associated herpesvirus) DNA in Kaposi's sarcoma lesions, AIDS Kaposi's sarcoma cell lines, endothelial Kaposi's sarcoma simulators, and the skin of immunosuppressed patients.

We used the polymerase chain reaction on 63 tissue specimens of histologically staged classic Kaposi's sarcoma (KS) from 40 patients, 14 specimens from 14 acquired immune deficiency syndrome (AIDS)-KS cases (all from the same geographic area over a 10-year period), and peripheral blood mononuclear cells from 1 of the non-AIDS KS patients to amplify a specific 210-bp genomic sequence of the newly discovered KS-associated herpesvirus (KSHV). Also tested were 86 benign and malignant endothelial lesions, which potentially simulated each KS histological stage and were further matched by age approximation and by sex with a classical KS specimen. The lesions included hemangioma, lymphangioma, pyogenic granuloma, and angiosarcoma. KSHV was also sought in multiple well characterized vascular endothelial cell lines from AIDS-KS lesions and in 20 mainly cutaneous benign and malignant lesions from 15 immunosuppressed transplant patients. Overall, 92% of KS tissue specimens, representing 88% of classical KS and 100% of AIDS-KS patients, and in addition the sample of peripheral blood mononuclear cell DNA, were positive as visualized on ethidium bromide gels and confirmed by Southern blot hybridization (only 1 case was negative on gell visualization but positive on Southern blot), thus confirming the close association of KSHV with KS of different clinical forms. None of the various other endothelial lesion, skin lesions in immunosuppressed patients, or AIDS-KS endothelial cell lines contained amplifiable KSHV DNA, which indicates that reactivation of KSHV is not present in the skin lesions of immunosuppressed patients and probably is not a ubiquitous agent that secondarily infects proliferative endothelium. The absence of amplifiable virus DNA in the cultured endothelium of KS suggests that the stimulus for angioproliferation originates in another host cell or under conditions not reproduced in culture. The polymerase chain reaction is a specific and sensitive means of verifying KS in the differential diagnosis of angioproliferative lessons.

Acquired Immunodeficiency Syndrome↗