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Biomedical subjects

T Glaser

Publications and source records attributed to T Glaser.

At least 19 recordsLinked to original sources
PubMed2006

Occupancy of dopamine D(1), D (2) and serotonin (2A) receptors in schizophrenic patients treated with flupentixol in comparison with risperidone and haloperidol.

RATIONALE: Flupentixol (FLX) has been used as a neuroleptic for nearly 4 decades. In vitro data show comparable affinity to dopamine D(2), D(1) and 5-HT(2A) receptors and recently, FLX showed to be not inferior to risperidone in schizophrenic patients with predominant negative symptomatology, which was implicated with flupentixol's interaction with 5-HT(2A) and/or D(1) receptors. OBJECTIVES: To assess in vivo receptor occupancy (RO) in patients clinically treated with FLX (n = 13, 5.7 +/- 1.4 mg/day) in comparison with risperidone (RIS, n = 11, 3.6 +/- 1.3 mg/day) and haloperidol (HAL, n = 11, 8.5 +/- 5.5 mg/day). MATERIALS AND METHODS: Each patient underwent two PET scans with 3-N-[(11)C]methylspiperone (target: frontal 5-HT(2A)), [(11)C]SCH23390 (striatal D(1)) or [(11)C]raclopride (striatal D(2)). RO was calculated as the percentage reduction of specific binding in comparison with healthy controls. RESULTS: D(2)-RO under FLX was between 50% and 70%, indicating an ED(50) of about 0.7 ng/ml serum. 5-HT(2A) and D(1)-RO was 20 +/- 10% and 20 +/- 5% (mean, SEM). Under HAL, D(1)-RO was 14 +/- 6% and under RIS not significantly different from zero. CONCLUSIONS: We were able to demonstrate a moderate 5-HT(2A) and D(1) occupancy under clinically relevant doses of flupentixol, albeit lower than expected from in vitro data and clearly below saturation. Therefore, if flupentixol's efficacy on negative symptoms is based on its interaction with 5-HT(2A) and/or D(1) receptors, it should be highly dependent on serum concentration and thus on dosage and metabolism. However, these data suggest that mechanisms other than D(1) or 5-HT(2A) antagonism may contribute to flupentixol's efficacy on negative symptoms.

Adult↗
PubMed2003

Gender-related differences in pharmacological relapse prevention with flupenthixol decanoate in detoxified alcoholics.

A study recently finished by our research group elucidated the effectiveness of flupenthixol decanoate (FLX) in maintaining abstinence in detoxified alcoholics. Flupenthixol decanoate is an established antipsychotic drug, which is well known for its mild antidepressant and anxiolytic activity as well as for its minimal sedation at low doses. It blocks dopamine binding at a number of receptor subtypes, primarily at D-1, D-2, D-3 and with less affinity at D4-receptors. It also affects serotonin binding at 5-HT2A and 5-HT2C receptors. In a double-blind placebo-controlled multicenter trial, 77 women and 204 men suffering from moderate or severe DSM-II-R alcohol dependence were randomly assigned to either 10 mg FLX or placebo both injected every second week over a period of 24 weeks (treatment phase) succeeded by a medication-free 24-weeks follow-up period. In the overall analysis the number of patients relapsed after 24 weeks of treatment (=main criterion of efficacy) was significantly higher in the FLX treated group (85.2%) than under placebo (65.5%). However, when differentiating this result according to sex the analysis revealed a gender-related discrepancy: while male patients had an almost 4-fold higher risk to relapse under FLX than under placebo (OR=3.95) this risk was barely elevated for female patients (OR=1.51). A significantly negative outcome due to FLX treatment was restricted to male alcoholics solely. In conclusion, gender-related differences to pharmacological relapse prevention with FLX have probably contributed to a better treatment outcome in women than in men.

Adult↗
PubMed2003

Flupenthixol versus risperidone: subjective quality of life as an important factor for compliance in chronic schizophrenic patients.

OBJECTIVE: The primary aim of this paper was to compare the effects of flupenthixol and risperidone on subjective quality of life and attitude towards medication in chronic schizophrenic patients with mainly negative symptoms. In a spectrum ranging from its typical end "haloperidol" to its atypical end "clozapine", flupenthixol has typical and atypical characteristics. METHODS: The effects of flupenthixol versus risperidone were investigated in a multicenter, double-blind trial, whereas subjective quality of life was assessed by means of the EuroQuol-Visual Analogue Scale and the patient satisfaction questionnaire. The attitude towards medication was assessed by means of the Drug Attitude Inventory-30 (DAI-30). RESULTS: Mean daily dose of study medication was 6.6 (SD 2.9) mg/day flupenthixol and 3.6 (SD 1.2) mg/day risperidone. Both groups showed a significant improvement regarding subjective quality of life and positive attitude towards medication. Especially the categories "control of their thoughts", concentration and "feeling better in general" ameliorated in both groups. In the flupenthixol group, the "ability to cope with stress", "feel more relaxed" and the "ability to achieve something" improved significantly more than in the risperidone group. CONCLUSIONS: (1) The spectrum of schizophrenia can be treated effectively with different neuroleptic treatments. (2) Flupenthixol especially improves the ability to cope with stress, the ability to achieve something and feeling more relaxed. (3) Subjective quality of life significantly increased with no difference between the groups.

Adolescent↗
PubMed2001

Identification of p21 as a target of cycloheximide-mediated facilitation of CD95-mediated apoptosis in human malignant glioma cells.

Human glioma cell lines differ in their requirement for the inhibition of protein synthesis to activate the CD95-dependent killing pathway. CD95 ligand (CD95L) induced mitochondrial cytochrome c release and processing of caspases 3, 7, 8 and 9 in LN-18 cells in the absence of an inhibitor of protein synthesis, cycloheximide (CHX). These biochemical changes were observed in LN-229 cells only in the presence of CHX. The viral caspase inhibitor, cytokine response modifier (crm)-A, inhibited mitochondrial cytochrome c release, caspase processing and cell death under all conditions. Ectopic expression of BCL-X(L) prevented processing of caspase 8 in LN-18 cells but not in LN-229 cells. Thus, caspase 8 activation is amplified through the release of cytochrome c in LN-18 cells but occurs mainly at the receptor in LN-229 cells. In contrast to BCL-2, BCL-X(L), X-linked inhibitor-of-apoptosis protein (XIAP) and FLICE-inhibitory protein (FLIP), the levels of the cyclin-dependent kinase (CDK) inhibitor, p21Waf/Cip1, rapidly decreased in response to CHX. P21 antisense oligonucleotides promoted caspase activation and mitochondrial cytochrome c release and induced strong sensitization to CD95-mediated apoptosis. These data place potentiating effects of CHX (i) to the activation of caspase 8 at the receptor in LN-229 cells as well as (ii) to a down-stream target at least in LN-18 cells, but probably both cell lines, that may be identical with p21Waf/Cip1.

Animals↗
PubMed2001

Sulfur K-edge X-ray absorption spectroscopy of 2Fe-2S ferredoxin: covalency of the oxidized and reduced 2Fe forms and comparison to model complexes.

Ligand K-edge X-ray absorption spectroscopy (XAS) provides a direct experimental probe of ligand-metal bonding. In previous studies, this method has been applied to mononuclear Fe-S and binuclear 2Fe-2S model compounds as well as to rubredoxins and the Rieske protein. These studies are now extended to the oxidized and reduced forms of ferredoxin I from spinach. Because of its high instability, the mixed-valence state was generated electrochemically in the protein matrix, and ligand K-edge absorption spectra were recorded using an XAS spectroelectrochemical cell. The experimental setup is described. The XAS edge data are analyzed to independently determine the covalencies of the iron-sulfide and -thiolate bonds. The results are compared with those obtained previously for the Rieske protein and for 2Fe-2S model compounds. It is found that the sulfide covalency is significantly lower in oxidized FdI compared to that of the oxidized model complex. This decrease is interpreted in terms of H bonding present in the protein, and its contribution to the reduction potential E degrees is estimated. Further, a significant increase in covalency for the Fe(III)-sulfide bond and a decrease of the Fe(II)-sulfide bond are observed in the reduced Fe(III)Fe(II) mixed-valence species compared to those of the Fe(III)Fe(III) homovalent site. This demonstrates that, upon reduction, the sulfide interactions with the ferrous site decrease, allowing greater charge donation to the remaining ferric center. That is the dominant change in electronic structure of the Fe(2)S(2)RS(4) center upon reduction and can contribute to the redox properties of this active site.

Electrochemistry↗
PubMed2001

Synthesis and separation of structural isomers of 2(3),9(10),16(17),23(24)-tetrasubstituted phthalocyanines.

The 2(3),9(10),16(17),23(24)-tetrasubstituted metalphthalocyanines 1-7 (M = In, Ni, Zn) were synthesized, as mixtures of four different structural isomers, from the corresponding 4-alkoxy-1,2-dicyanobenzenes and the appropriate metal salts. Separation of the four structural isomers was successfully achieved on a C30 alkyl phase by high-performance liquid chromatography (HPLC). The determination of the point groups of the structural isomers was carried out for 1 and 3, the composition of the structural isomers of 4-7 was accomplished by comparing their retention times and UV/Vis spectra with the data of 1 and 3. For the phthalocyanines 8-10 and the naphthalocyanines 11 and 12 only the C4h and D2h isomers could be separated.

Journal Article↗
PubMed2001

Caspase-dependent chemotherapy-induced death of glioma cells requires mitochondrial cytochrome c release.

Chemotherapeutic drug-induced apoptosis of human malignant glioma cells involves the death receptor-independent activation of caspases other than caspases 3 or 8 (Glaser et al., Oncogene 18, 5044-5053, 1999). Here, we report that caspases 1, 2, 3, 7, 8, and 9 are constitutively expressed in most human malignant glioma cell lines. Cytotoxic drug-induced apoptosisinvolves delayed activation of caspases 2, 7, and 9, but not 8 and 3, and is blocked by a broad spectrum caspase inhibitor, zVAD-fmk. Cytochrome c release from mitochondria precedes caspase activation during drug-induced apoptosis and is unaffected by zVAD-fmk or ectopic expression of the viral caspase inhibitor, crm-A. In contrast, ectopic expression of BCL-X(L) prevents drug-induced cytochrome c release, caspase activation and cell death. Thus, cancer chemotherapy targets the mitochondrial, caspase-dependent death pathway in human malignant glioma cells.

Amino Acid Chloromethyl Ketones↗
PubMed2001

Combined HPLC-MS and HPLC-NMR on-line coupling for the separation and determination of lutein and zeaxanthin stereoisomers in spinach and in retina.

The determination and unambiguous identification of carotenoid stereoisomers from biological tissues, avoiding isomerization and oxidation due to the extraction process, is still a major challenge. Particularly, the analysis of lutein and zeaxanthin stereoisomers is of great importance, as these are the main constituents of the macula lutea, the central part of the human retina, and act as possible agents in the prevention and treatment of age-related macular degeneration (AMD). By combining a mild and quick extraction technique such as matrix solid-phase dispersion together with high-performance liquid chromatography (HPLC), the extremely light and oxygen sensitive lutein and zeaxanthin stereoisomers are extracted, enriched, and separated directly from the solid plant or tissue samples, excluding preparation of artifacts. HPLC separations are performed with C30 phases due to their enhanced shape selectivity compared to C18 phases and on-line coupled to mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy. By using HPLC-MS with atmospheric pressure chemical ionization, the lutein stereoisomers can be distinguished from the zeaxanthin stereoisomers within one chromatographic run in the upper picogram range, whereas HPLC-NMR coupling allows the unequivocal identification of each stereoisomer with a concentration in the upper nanogram range. This article provides an analytical method for the artifact-free determination of lutein and zeaxanthin stereoisomers directly from the solid biological tissue spinach as a source of carotenoids and retina as the sphere of activity for AMD. In addition, the structures of these stereoisomers were unambiguously elucidated by employing hyphenated analytical techniques.

Chromatography, High Pressure Liquid↗
PubMed2001

S K-edge X-ray absorption studies of tetranuclear iron-sulfur clusters: mu-sulfide bonding and its contribution to electron delocalization.

X-ray absorption spectroscopy (XAS) at the sulfur ( approximately 2470 eV) and chlorine ( approximately 2822 eV) K-edges has been applied to a series of 4Fe-4S model complexes. These are compared to 2Fe-2S model complexes to obtain insight into the localized ground state in the mixed-valence dimer versus the delocalized ground state in the mixed-valence tetramer. The preedges of hypothetical delocalized mixed-valence dimers [Fe(2)S(2)](+) are estimated using trends from experimental data and density functional calculations, for comparison to the delocalized mixed-valence tetramer [Fe(4)S(4)](2+). The differences between these two mixed-valence sites are due to the change of the sulfide-bridging mode from micro(2) to micro(3). The terminal chloride and thiolate ligands are used as spectator ligands for the electron density of the iron center. From the intensity of the preedge, the covalency of the terminal ligands is found to increase in the tetramer as compared to the dimer. This is associated with a higher effective nuclear charge on the iron in the tetramer (derived from the energies of the preedge). The micro(3)-bridging sulfide in the tetramer has a reduced covalency per bond (39%) as compared to the micro(2)-bridging sulfide in the dimer (51%). A simple perturbation model is used to derive a quadratic dependence of the superexchange coupling constant J on the covalency of the metal ions with the bridging ligands. This relationship is used to estimate the superexchange contribution in the tetramer (J = -156 cm(-)(1)) as compared to the mixed-valence dimer (J = -360 cm(-)(1)). These results, combined with estimates for the double exchange and the vibronic coupling contributions of the dimer sub-site of the tetramer, lead to a delocalized S(t) = (9)/(2) spin ground state for the mixed-valence dimer in the tetramer. Thus, the decrease in the covalency, hence the superexchange pathway associated with changing the bridging mode of the sulfides from micro(2) to micro(3) on going from the dimer to the tetramer, significantly contributes to the delocalization of the excess electron over the dimer sub-site in the tetramer.

Binding Sites↗
PubMed2001

The eyeless mouse mutation (ey1) removes an alternative start codon from the Rx/rax homeobox gene.

The eyeless inbred mouse strain ZRDCT has long served as a spontaneous model for human anophthalmia and the evolutionary reduction of eyes that has occurred in some naturally blind mammals. ZRDCT mice have orbits but lack eyes and optic tracts and have hypothalamic abnormalities. Segregation data suggest that a small number of interacting genes are responsible, including at least one major recessive locus, ey1. Although predicted since the 1940s, these loci were never identified. We mapped ey1 to chromosome 18 using an F2 genome scan and there found a Met10-->Leu mutation in Rx/rax, a homeobox gene that is expressed in the anterior headfold, developing retina, pineal, and hypothalamus and is translated via a leaky scanning mechanism. The mutation affects a conserved AUG codon that functions as an alternative translation initiation site and consequently reduces the abundance of Rx protein. In contrast to a targeted Rx null allele, which causes anophthalmia, central nervous system defects, and neonatal death, the hypomorphic M10L allele is fully viable.

Alternative Splicing↗
PubMed2001

Positive and negative life changes following sexual assault.

A longitudinal study was conducted to investigate (a) the timing and course of posttraumatic growth and (b) the relations between positive and negative life changes and posttraumatic distress among recent female sexual assault survivors (N = 171). Most survivors reported positive change even at 2 weeks postassault. Positive changes generally increased over time and negative changes decreased, although change in different domains followed different courses and there was significant individual variability in change patterns. Both positive and negative changes were associated with distress in expected ways, although the relations with negative changes were stronger. The least distress at 12 months was reported by those who noted positive life changes at both 2 weeks and 12 months postassault. Implications for theory and research on posttraumatic growth are discussed.

Adolescent↗
PubMed2001

Death receptor-independent cytochrome c release and caspase activation mediate thymidine kinase plus ganciclovir-mediated cytotoxicity in LN-18 and LN-229 human malignant glioma cells.

Suicide gene therapy using viral transfer of herpes simplex virus type I (HSV-1) thymidine kinase (TK) and subsequent ganciclovir (GCV) chemotherapy was the first approach used in clinical trials of somatic gene therapy for glioblastoma. The molecular pathways mediating TK/GCV-induced cell death remain to be elucidated. Here, we report that adenoviral (Ad)-TK/GCV-induced death is p53-independent and does not involve altered CD95 or CD95L expression. Ectopic expression of the preferential caspase 8 inhibitor, crm-A, inhibits Ad-CD95L-induced cell death but has no effect on TK/GCV cytotoxicity. LN-18 glioma cells selected for resistance to death receptor-mediated cell death do not acquire cross-resistance to TK/GCV. TK/GCV triggers mitochondrial cytochrome c release and activation of caspases 3, 7, 8 and 9 in a death receptor-independent manner. These events are associated with the loss of BCL-X(L). Forced expression of a BCL-X(L) transgene, or co-exposure to a pseudosubstrate caspase inhibitor, zVAD-fmk, inhibit TK/GCV cytotoxicity. Double-transfected cell lines expressing crm-A and enhanced green fluorescent protein (eGFP) show that the bystander effect in vitro is also death receptor- and caspase 8-independent. TK/GCV therapy does not kill glioma cells in synergy with cancer chemotherapy drugs, including lomustine, temozolomide and topotecan. In contrast, there is strong synergy of TK/GCV and CD95L. Thus, TK/GCV-induced cell death involves a mitochondria-dependent loop of caspase acvtivation that can be synergistically enhanced by death receptor agonists such as CD95L. TK/GCV-mediated sensitization of glioma cells to CD95L expressed on immune effector cells or parenchymal brain cells might account for the immune system's and bystander effects of TK/GCV therapy observed in rodent glioma models in vivo.

Adenoviridae↗
PubMed2001

Transcriptional regulation of IGF-I receptor gene expression by the PAX3-FKHR oncoprotein.

Chromosomal translocations that disrupt the molecular organization of transcription factors are typical of a variety of solid and hematopoietic cancers. Alveolar rhabdomyosarcoma (ARMS), a paediatric soft tissue malignant tumour, is characterized by the recurrent translocation t(2;13)(q35;q14) that fuses the 5' DNA binding domain-encoding sequences of the Pax3 gene with the 3' sequences of the FKHR gene. The insulin-like growth factor (IGF) system has an important role in muscle development as well as in the aetiology of paediatric sarcomas, including ARMS. In the present study the potential regulation of the IGF-I receptor (IGF-I-R) gene by PAX3-FKHR at the transcriptional level was investigated. PAX3-FKHR was able to transactivate the IGF-I-R promoter in sarcoma-derived cell lines, whereas PAX3 exhibited a reduced potency in comparison to the fusion protein. Furthermore, transfection of the chimera induced a significant increase in the endogenous levels of IGF-I-R protein, suggesting that the IGF-I-R gene is a physiologically-relevant molecular target for the PAX3-FKHR oncogene.

Child↗
PubMed2001

Intracellular location and nuclear targeting of the Spi-1, Spi-2 and Spi-3 gene-derived serine protease inhibitors in non-secretory cells.

Proteases and their inhibitors are indispensable for the regulated activation and/or degradation of structural and functional proteins involved in basic cellular processes, e.g. in cell cycle control, cell growth, differentiation and apoptosis. In this context the serine protease inhibitors derived from the murine Spi-1, Spi-2 and Spi-3 genes, and their human homologs, deserve reconsideration. Microsequencing data indicate that a fraction of the three serpins has the capability to constitute a well characterized proteinase K, high salt and SDS-stable complex which coisolates with DNA under salting out conditions from various cell and tissue types. This tight association with DNA isolated under conditions designed to deproteinize DNA efficiently points to an in situ preformed chromatin complex. Accordingly, in addition to their well known functions as 'serum protease inhibitors' the Spi-1 and Spi-2 gene-derived proteins appear to have intracellular functions as well. The involvement of the three serpins in chromatin complexes requires their nuclear translocation. Application of (enhanced) green fluorescent protein technology and optical section microscopy reveals that truncation of the N-terminal signal sequences of the Spi-1 and Spi-2 gene-encoded proteins is a prerequisite for their nuclear translocation while non-truncated fusion proteins are enriched at the nuclear indentation which is the site of the Golgi apparatus and the centrosome. The identification of new species of intracellular serpins is of potential interest with respect to accumulating evidence for serine protease inhibitor-dependent inhibition or prevention of apoptosis.

Acute-Phase Proteins↗
PubMed2001

Math5 is required for retinal ganglion cell and optic nerve formation.

The vertebrate retina contains seven major neuronal and glial cell types in an interconnected network that collects, processes and sends visual signals through the optic nerve to the brain. Retinal neuron differentiation is thought to require both intrinsic and extrinsic factors, yet few intrinsic gene products have been identified that direct this process. Math5 (Atoh7) encodes a basic helix-loop-helix (bHLH) transcription factor that is specifically expressed by mouse retinal progenitors. Math5 is highly homologous to atonal, which is critically required for R8 neuron formation during Drosophila eye development. Like R8 cells in the fly eye, retinal ganglion cells (RGCs) are the first neurons in the vertebrate eye. Here we show that Math5 mutant mice are fully viable, yet lack RGCs and optic nerves. Thus, two evolutionarily diverse eye types require atonal gene family function for the earliest stages of retinal neuron formation. At the same time, the abundance of cone photoreceptors is significantly increased in Math5(-/-) retinae, suggesting a binary change in cell fate from RGCs to cones. A small number of nascent RGCs are detected during embryogenesis, but these fail to develop further, suggesting that committed RGCs may also require Math5 function.

Animals↗
PubMed2000

3' deletions cause aniridia by preventing PAX6 gene expression.

Aniridia is a panocular human eye malformation caused by heterozygous null mutations within PAX6, a paired-box transcription factor, or cytogenetic deletions of chromosome 11p13 that encompass PAX6. Chromosomal rearrangements also have been described that disrupt 11p13 but spare the PAX6 transcription unit in two families with aniridia. These presumably cause a loss of gene expression, by removing positive cis regulatory elements or juxtaposing negative DNA sequences. We report two submicroscopic de novo deletions of 11p13 that cause aniridia but are located >11 kb from the 3' end of PAX6. The clinical manifestations are indistinguishable from cases with chain-terminating mutations in the coding region. Using human x mouse retinoblastoma somatic cell hybrids, we show that PAX6 is transcribed only from the normal allele but not from the deleted chromosome 11 homolog. Our findings suggest that remote 3' regulatory elements are required for initiation of PAX6 expression.

Animals↗