PubMed Health⌕ Search

Biomedical subjects

K Addicks

Publications and source records attributed to K Addicks.

At least 19 recordsLinked to original sources
PubMed2006

Transplantation of bone marrow-derived mesenchymal stem cells rescue photoreceptor cells in the dystrophic retina of the rhodopsin knockout mouse.

BACKGROUND: Retinitis pigmentosa belongs to a large group of degenerative diseases of the retina with a hereditary background. It involves loss of retinal photoreceptor cells and consequently peripheral vision. At present there are no satisfactory therapeutic options for this disease. Just recently the use of mesenchymal stem cells has been discussed as one therapeutical option for retinal degeneration, as they have been shown to differentiate into various cell types, including photoreceptor cells. In this article we wanted to investigate the potency of mesenchymal stem cells to induce rescue effects in an animal model for retinitis pigmentosa, the rhodopsin knockout mouse. METHODS: For the experiments, three experimental groups of 10 animals each were formed. The first group consisted of untreated rhodopsin knockout (rho(-/-)) animals used as controls. The second group consisted of rho(-/-) mice that had received an injection of mouse mesenchymal stem cells, which were transduced using an adenoviral vector containing the sequence for the green fluorescent protein (GFP) prior to transplantation. In the third sham group, animals received an injection of medium only. Thirty-five days after transplantation, GFP-expressing cells were detected in whole-mount preparations of the retinas as well as in cryostat sections. For the detection of rescue effects, semi-thin sections of eyes derived from all experimental groups were produced. Furthermore, rescue effects were also analysed ultrastructurally in ultrathin sections. RESULTS: Histological analysis revealed that after transplantation, cells morphologically integrated not only into the retinal pigment epithelium but also into layers of the neuroretina displaying neuronal and glial morphologies. Furthermore, significant rescue effects, as demonstrated by the occurrence of preserved photoreceptor cells, were detected. CONCLUSIONS: Our data indicate that mesenchymal stem cells can prolong photoreceptor survival in the rhodopsin knockout mouse, also providing evidence of a therapeutical benefit in retinitis pigmentosa.

Adenoviridae↗
PubMed2006

Bradykinin mediates phosphorylation of eNOS in odontoblasts.

While the activation of eNOS by Akt/PKB-dependent phosphorylation, leading to NO release, and the inhibition of enzyme activity by bradykinin (BK)-mediated phosphorylation of eNOS in endothelial cells are established, the phosphorylation of eNOS in odontoblasts is unknown. To clarify the regulation of eNOS in odontoblasts by BK, we examined the phosphorylation of eNOS, Akt/PKB, and ERK1/2 in odontoblasts of rat molars. BK (10(-7) M) transiently induced the phosphorylation of eNOS at Ser1177, Akt/PKB in odontoblasts, while it induced the phosphorylation of eNOS at Thr495 throughout the entire period of BK treatment. BK receptor 2 antagonist HOE 140 (10(-6) M) significantly reduced signal intensities of phosphorylated-eNOS at Ser1177, Thr495, and phosphorylated-Akt/PKB. These results suggest that BK has dual effects on the activation of eNOS in odontoblasts, the Akt/PKB-dependent up-regulation of eNOS by the transient phosphorylation at Ser1177, and the ERK1/2-independent down-regulation of eNOS by the phosphorylation at Thr495.

Animals↗
PubMed2005

NO-cGMP signaling molecules in cells of the rat molar dentin-pulp complex.

By the formation of cyclic guanosine 3',5'-monophosphate (cGMP), nitric oxide (NO)-sensitive enzyme-soluble guanylate cyclase (sGC) plays a receptor role for NO within the NO-cGMP signaling cascade, which is involved in vasodilatation and neurotransmission. The hypothesis that NO-cGMP signaling molecules modulate cells of the dentin-pulp complex was investigated in rat molars by histochemical, immunohistochemical, immuno-ultrastructural, and organ bath techniques. NO synthase (NOS) I-III, the sGC alpha(2)-subunit/beta(1)-subunit, and cGMP were detected in odontoblasts and blood vessels. NOS I, sGC alpha(2), and cGMP were identified in nerve fibers. Treatment of rat molars with the NO donor NONOate (10(-5) M) increased cGMP staining intensities in blood vessels and odontoblasts, while NO synthase inhibitor L-NAME (10(-4) M) attenuated intensity of the reaction products for cGMP, suggesting an effect of endogenous NO on sGC. These correlations of patterns and alterations of cGMP staining intensities after treatment with the NO donor or NO inhibitor might represent an NO-sGC-cGMP signaling-dependent modulation of odontoblasts, blood vessels, and nerve fibers in the dentin-pulp complex.

Animals↗
PubMed2004

Transient expression of NOS-II during development of the murine enteric nervous system.

In the enteric nervous system, nitric oxide (NO) is regarded as an important messenger for the non-adrenergic and non-cholinergic neurotransmission. Synthesized mainly by the constitutive nitric oxide synthase (NOS) isoforms NOS I and NOS III, this molecule exerts prejunctional inhibitory effects in the submucosal plexus as well as relaxation of enteric smooth muscles. In order to elucidate the role for NO during enteric development, we looked for the expression of all three NOS-isoforms in the enteric nervous system during mouse development from E8 to E20 using immunohistochemistry. Starting around midgestation, a transient expression of the NOS-II isoform during the very early development of enteric neurones was detected in parallel to that of HNK-1 exclusively in the myenteric plexus. Similar to findings for other neuronal systems, NOS-I and NOS III isoforms could be traced starting significantly later to increase toward the end of embryonic development when NOS II immunoreactivity faded and a strong expression of the vasointestinal peptide could be detected. In contrast to the NOSII expression, the constitutive isoforms can also be detected in the submucosal plexus. Altogether, these findings suggest NOS-II to be exclusively involved during early steps of enteric nervous system development. Absence of downstream signalling elements, such as sGC and cGMP both in neurons and in enteric muscle until the end of the second third of gestation, may indicate different effects executed by NO during development, expressed by Ca(2+) -dependent and Ca(2+) -independent NOS isoforms.

Animals↗
PubMed2004

Iris pigment epithelial cells: a possible cell source for the future treatment of neurodegenerative diseases.

For the treatment of neurodegenerative disorders such as Parkinson's disease cell or gene therapeutical options are increasingly verified. For such approaches, neural stem cells or astrocytes are discussed as possible cell candidates. As also fetal retinal pigment epithelial cells have been successfully tested for such therapeutical options, we investigated the potential of iris pigment epithelial cells as an autologous source for future cell replacement therapies. Using the ELISA technique, we looked for the secretion of neurotrophic factors under basal and stimulated conditions by iris pigment epithelial cells (IPE) cells and compared them with the secretion of retinal pigment epithelial cells (RPE) cells. As iron plays a causative role in cell death during Parkinson's disease, the iron-binding capacity by IPE cells was investigated. Furthermore, we checked the integrative capacity of IPE cells after transplantation into the striatum of adult rats. Our data reveal that IPE cells produce and secrete a variety of neurotrophic factors which can be stimulated after treatment with cytokines. Following transplantation, the cells can be easily detected by their pigmentation, survive for at least 8 weeks and as shown by electron microscopy integrate within the host tissue. Moreover, cells can be transduced with high efficiency using a third generation adenoviral vector, making them promising vehicles to locally deliver therapeutic proteins for the treatment of neurodegenerative diseases in a combined cell and gene therapeutical approach.

Animals↗
PubMed2003

Morphology and density of initial lymphatics in human myocardium determined by immunohistochemistry.

BACKGROUND: Myocardial edema is a common finding in congestive heart failure, transplant rejection, and cardiomyopathy. Although pathological alterations in the lymphatic morphology are part of the underlying disease, knowledge on these changes is limited. However, lymphatic morphology may be investigated by immunohistochemical staining for fms-like tyrosine 4 kinase (flt-4), which is specific for lymphatic endothelium in adult tissue. METHODS: We used myocardial tissue of ventricular out flow tract taken from five human semilunar valves harvested as allografts but unsuitable for implantation for analysis, performing immunohistochemical staining for flt-4 with a commercially available antibody. Lymphatic morphometry was completed according Gundersen method. RESULTS: Immunohistochemical staining for flt-4 resulted in successful labeling of lymph capillaries in adult human myocardium. Lymph capillary density was calculated as 50.7 +/- 12.5 per mm2 and average diameter was 3.7 +/- 0.7 microm. Conclusions. Lymph capillary morphology in human myocardium may be successfully determined by immunohistochemical staining for flt-4. Tissue samples as small as myocardial biopsies may be used for analysis. Using this method, morphological changes in myocardial lymphatics may be investigated in various cardiovascular diseases.

Adult↗
PubMed2003

Neural precursor cells as carriers for a gene therapeutical approach in tumor therapy.

Conventional therapeutical approaches such as surgery, radiotherapy, or chemotherapy have been shown to be rather unsuccessful in the treatment of infiltrative growing tumors such as the malignant glioblastoma multiforme. Thus, new therapeutical strategies have to be developed that are suitable for inducing cell death also in migrating tumor cells. These new therapeutical stategies include cell and/or gene therapeutical approaches. We demonstrate that glial-restricted progenitor cells as well as embryonic stem cell-derived neural stem cells belong to cell populations applicable to such therapeutical concepts. Both cell types can be efficiently transduced using a third-generation high-capacity "gutless" adenoviral vector, and show a tropism for the F98 glioma cells by migrating towards a spheroid of F98 glioma cells with a tendency to form a barrier around the tumor spheroid in an in vitro tumor confrontation model. Moreover, in a migration assay, secretion products of glial-restricted precursor cells have shown a potency to inhibit the migratory activity of glioma cells in vitro. In vivo, F98 glioma cell-derived tumor formation in the right striatum resulted in migration of glial as well as neural precursor cells towards the tumor area when cotransplanted in the corpus callosum of the contralateral hemisphere. After arrival, both cell types surround the tumor mass and even invade the experimentally induced tumor. These data indicate that glial-restricted as well as embryonic stem cell-derived neural precursor cells are good candidates as carriers for an ex vivo gene therapeutical approach in tumor therapy.

Adenoviridae↗
PubMed2002

NOS-II is involved in early differentiation of murine cortical, retinal and ES cell-derived neurons-an immunocytochemical and functional approach.

Nitric oxide (NO), a cell-derived highly diffusible and unstable gas is regarded to be involved in inter- and intracellular communication in the nervous system. Based on findings about the expression of the inducible NO synthase (NOS) isoform during development of early mouse olfactory as well as vestibulocochlear receptor neurons, we intended to prove a general role of this isoform for neuronal differentiation. Using immunohistochemical techniques, an exclusive expression of the inducible NOS-II isoform in early post-mitotic neurons of the developing mouse cortex and retina can be detected. In a pharmacological approach using cultures of the mouse cortex as well as embryonic stem cell-derived neural precursor cells, we investigated the functional role of NO on initial neuronal differentiation. Effects of NOS inhibitors and NO donors on the morphological differentiation were correlated with developmentally regulated calcium current densities, focusing on the effects of the specific NOS-II inhibitor GW 274150. Furthermore, involvement of the soluble guanylate cyclase (sGC)/cGMP signaling cascade was pharmacologically investigated. Our data indicate that while a specific block of NOS-II provokes a clear inhibition of neurite outgrowth formation as well as a decrease of calcium current densities, the inverse is true for exogenous NO donation. In line with lacking immunoreactivity for the sGC and cGMP there are only minor effects of compounds manipulating the sGC/cGMP pathway, suggesting the downstream sGC/cGMP pathway not to be essential in these early differentiation steps.

Animals↗
PubMed2002

MAP kinase 1/2 (Erk 1/2) and serine/threonine specific protein kinase Akt/PKB expression and activity in the human corpus cavernosum.

Nitric oxide (NO) is an important mediator in the cavernosal smooth muscle relaxation that causes erections. The purpose of this study was to examine the existence, distribution and phosphorylation stage of two recently discovered key enzymes for NO regulation in human cavernosal tissue, the MAP Kinase 1/2 (Erk 1/2) and the serine/threonine specific protein kinase Akt/PKB. The expression of the enzymes was examined in corpus cavernosum specimens taken from both potent men and from patients with long-term impotence. There was a distinct difference in the activation stage of the MAP Kinase 1/2 (Erk 1/2) between endothelium and smooth muscle cells in potent patients. This finding gives evidence for a cell-type-specific regulation of the eNOS-dependent NO release. Furthermore, we found a higher basal level of active MAP Kinase 1/2 (Erk 1/2) in impotent patients. This finding gives the first evidence for an inhibitory influence of MAP Kinase 1/2 (Erk 1/2) on cavernosal eNOS activity.

Adolescent↗
PubMed2002

Intracerebral transplantation and successful integration of astrocytes following genetic modification with a high-capacity adenoviral vector.

To investigate the ability of genetically modified astrocytes to integrate into adult rat brain, two spontaneously immortalized cell lines and the allogenic nontumorigenic glioma cell line F98 were transduced with a high-capacity adenoviral vector (HC-Adv) expressing the EGFP gene from the hCMV promoter. In organotypic slice cultures the transduced astrocytes were shown to integrate into the brain tissue. Following transplantation of the transduced astrocytes into the striatum of adult rats, the transplanted cells survived at least for 6 weeks, continuously expressed the EGFP transgene, in close neighborhood with cells of the recipient tissue executing their differentiation capacity along the glial lineage. Thus, HC-Adv transduced astrocytes are promising vehicles to locally deliver therapeutic proteins for the treatment of neurodegenerative diseases.

Adenoviridae↗
PubMed2001

Nitric oxide synthase expression and function in embryonic and adult cardiomyocytes.

Nitric oxide (NO) is an important signalling molecule that plays a relevant role in different cell systems, among them the adult heart. The effects of NO are primarily mediated through modulation of Ca(2+) homeostasis, myofibrillar contractility, and metabolic regulation in cardiomyocytes. Recent evidence also suggests an important role of NO for cardiomyogenesis by modulating proliferation and differentiation and regulating cardiac function. In the embryonic, but also the healthy and diseased, adult mammalian heart, the inducible (iNOS) and the endothelial (eNOS) nitric oxide synthases (NOS) are detected. However, the expression pattern of NO and its function differ during development. Furthermore, under pathophysiological conditions NOS expression can also change and cause impairment of cardiac performance and cytotoxic effects. The present review focuses on the role and function of NO during cardiomyogenesis, the mechanisms responsible for eNOS availability, and the paracrine effects of NO generated by cardiomyocytes.

Animals↗
PubMed2001

Disruption of cytoskeletal integrity impairs Gi-mediated signaling due to displacement of Gi proteins.

beta1 integrins play a crucial role as cytoskeletal anchorage proteins. In this study, the coupling of the cytoskeleton and intracellular signaling pathways was investigated in beta1 integrin deficient (-/-) embryonic stem cells. Muscarinic inhibition of the L-type Ca2+ current (ICa) and activation of the acetylcholine-activated K+ current (IK,ACh) was found to be absent in beta1 integrin-/- cardiomyocytes. Conversely, beta adrenoceptor-mediated modulation of ICa was unaffected by the absence of beta1 integrins. This defect in muscarinic signaling was due to defective G protein coupling. This was supported by deconvolution microscopy, which demonstrated that Gi exhibited an atypical subcellular distribution in the beta1 integrin-/- cardiomyocytes. A critical role of the cytoskeleton was further demonstrated using cytochalasin D, which displaced Gi and impaired muscarinic signaling. We conclude that cytoskeletal integrity is required for correct localization and function of Gi-associated signaling microdomains.

Acetylcholine↗
PubMed2001

Heme oxygenase-2 immunoreactivity in developing and mature bovine olfactory epithelium.

In the present study the localization of heme oxygenase-2 (HO-2) in developing and mature olfactory epithelium of the bovine is investigated using immunohistochemistry and post embedding immunogold labelling. HO-2 immunoreactivity is first seen in epithelial cells localized along the luminal surface of the olfactory pit. Up to midgestation the number of HO-2 immunoreactive cells increases throughout all layers of the developing olfactory epithelium. From midgestation through adulthood immunostaining is restricted to perinuclear cytoplasm and axons of mature olfactory receptor neurons localized in intermediate epithelial regions. The temporal and spatial expression patterns of HO-2 immunohistochemistry support the notion that CO plays a role in neuronal differentiation while its presence in mature neurons might be functionally related to olfactory transduction.

Age Factors↗
PubMed2001

Ischemia increases detectable endothelial nitric oxide synthase in rat and human myocardium.

The aims of the present study were to establish if myocardial ischemia/reperfusion is associated with altered eNOS activity and if myocardial eNOS detection depends on its activity. We determined detectable eNOS in (1) myocardium of isolated perfused rat hearts subjected to either global or regional ischemia and (2) in left ventricular biopsies from patients undergoing two different methods of myocardial protection (i.e., intermittent cold blood cardioplegia and continuous coronary perfusion with warm, beta-blocker-enriched blood) during coronary artery surgery. NOS detection was performed by NADPH-d staining and three eNOS-antibodies against different eNOS epitopes. In addition, activity dependent alteration of detectable eNOS was proofed by bradykinin treatment for 2 to 10 min. Ischemic and receptor mediated eNOS activation increased NADPH-d reactivity and eNOS immunoreaction as measured by antibodies against either amino acids of a central bovine eNOS domain or the human eNOS N-terminal end. In contrast, the antibody against the human eNOS C-terminal end exhibited no alteration of eNOS immunoreaction. The transient eNOS activation was associated with increased cGMP content. In human myocardium subjected to ischemia during cardiac surgery we found that early reperfusion increases eNOS activity. These data demonstrate a strong association between myocardial ischemia/reperfusion and increased eNOS activity as measured by immunocytochemical staining against specific eNOS epitopes. It appears that eNOS activation and subsequent NO release may act as a regulatory system to counter balance the potentially deleterious effects of myocardial ischemia/reperfusion.

Adrenergic beta-Antagonists↗
PubMed2001

Immunohistochemical detection of vascular endothelial growth factor (VEGF) and VEGF receptors Flt-1 and KDR/Flk-1 in the cochlea of guinea pigs.

Vascular endothelial growth factor (VEGF) is known as an endothelial cell-specific mitogen. There are no reports concerning the presence of VEGF in the inner ear. To gain information, immunohistochemical analysis using specific antibodies to VEGF and to both known VEGF receptors Flt-1 and KDR/Flk-1 was performed on paraffin-sectioned temporal bones from five guinea pigs. Immunoreactivity of VEGF, Flt-1 and KDR/Flk-1 was detectable in spiral ganglion cells. VEGF could also be found in the endothelium of blood vessels, in the spiral ligament and in the organ of Corti. Flt-1 was found in the limbus epithelium, in all supporting cells of the organ of Corti, in Claudius cells, cells of the sulcus and in the spiral ligament. Flk-1 could be detected in some supporting cells of the organ of Corti (inner pillar cells and Deiters' cells). Immunoreactivity to Flk-1 was also found in endothelium of blood vessels and in the spiral ligament. Hair cells showed VEGF immunostaining, but did not contain staining to Flt-1 nor Flk-1. In the stria vascularis any immunoreactivity to all used VEGF and VEGF receptor antibodies could not be detected. The findings were supported by Western blot analysis on inner ear tissues and ovaries from guinea pigs. We may conclude that the growth factor VEGF and both receptors participate in cochlear physiology.

Animals↗
PubMed2001

Wallerian degeneration of injured axons and synapses is delayed by a Ube4b/Nmnat chimeric gene.

Axons and their synapses distal to an injury undergo rapid Wallerian degeneration, but axons in the C57BL/WldS mouse are protected. The degenerative and protective mechanisms are unknown. We identified the protective gene, which encodes an N-terminal fragment of ubiquitination factor E4B (Ube4b) fused to nicotinamide mononucleotide adenylyltransferase (Nmnat), and showed that it confers a dose-dependent block of Wallerian degeneration. Transected distal axons survived for two weeks, and neuromuscular junctions were also protected. Surprisingly, the Wld protein was located predominantly in the nucleus, indicating an indirect protective mechanism. Nmnat enzyme activity, but not NAD+ content, was increased fourfold in WldS tissues. Thus, axon protection is likely to be mediated by altered ubiquitination or pyridine nucleotide metabolism.

Action Potentials↗
PubMed2001

Differential expression of two carbohydrate epitopes, CD15 and HNK-1, in developing vertebrate olfactory receptor neurones.

According to the view of differentiation-related alterations in the glycosylation pattern of neurones, recent studies have shown development dependent expression patterns of lactoseries carbohydrate epitopes, CD15 and HNK-1, on olfactory receptor neurones in rats and chicks. In order to evaluate a general role for these epitopes during development of vertebrate olfactory receptor neurones, this investigation focuses on the situation in the mouse, bovine and Xenopus olfactory epithelium. In all three species CD15 expression was found on a subpopulation of morphologically mature receptor cells starting at the time of initial synaptogenesis. Whereas for bovine and Xenopus the timetable of HNK-1 expression is similar to that described for the chick, suggesting involvement in pathfinding, in the mouse HNK-1 is found on immature cells when mature CD15 positive receptor cells could already be discerned. By our results a role for CD15 during establishment of synaptic contacts and for HNK-1 during their formation is suggested.

Animals↗