PubMed Health⌕ Search

Biomedical subjects

T Wenzel

Publications and source records attributed to T Wenzel.

35 records · Page 2Linked to original sources
PubMed1995

Conformational constraints in protein degradation by the 20S proteasome.

Conformationally stabilized peptides and unfolding intermediates of bovine alpha-lactalbumin have been used to define the degree of unfolding required for degradation by 20S proteasomes. It appears that complete unfolding and the absence of disulphide bonds are prerequisites for degradation, suggesting that a relatively narrow opening controls access to the inner proteolytic compartment of the barrel-shaped proteasome. This is corroborated by electron microscopy studies showing that the insulin B-chain, which is otherwise easily degraded, cannot pass the orifice of this putative peptide channel when a Nanogold particle with a diameter of approximately 2 nm is covalently attached to it.

Amino Acid Sequence↗
PubMed1994

Existence of a molecular ruler in proteasomes suggested by analysis of degradation products.

Analysis of the degradation products from two proteins, the insulin B-chain and human hemoglobin, generated by archaebacterial Thermoplasma acidophilum 20 S proteasomes, revealed an unexpectedly broad specificity. In spite of the vast number of different peptides found, they fell into a rather narrow size range. This suggests that a molecular ruler exists which determines the length of the cleavage products.

Amino Acid Sequence↗
PubMed1993

Thermoplasma acidophilum proteasomes degrade partially unfolded and ubiquitin-associated proteins.

It is shown that proteasomes from the arachaebacterium Thermoplasma acidophilum selectively degrade substrate proteins partially unfolded by phenylhydrazine- or hydrogen peroxide-treatment. Surprisingly, the pre-incubation of the substrate proteins with ubiquitin is also sufficient to render them susceptible to proteolytic degradation by proteasomes. We propose that, upon spontaneously associating with the substrate protein, ubiquitin exerts a chaotropic effect on it; this may involve the exposure of hydrophobic segments of the polypeptide chain which are recognized by the binding sites of the proteasome.

Chromatography, High Pressure Liquid↗
PubMed1993

Activation of protein kinase C in vitro and in intact cells or synaptosomes determined by acetic acid extraction of MARCKS.

MARCKS is a widespread cellular phosphoprotein that migrates at 80-87 kDa on polyacrylamide gels. It is phosphorylated apparently exclusively by protein kinase C (PKC) and its phosphorylation in intact cells can be used as an index of intracellular PKC activation. Most methods for the determination of its phosphorylation state in vitro or in intact cells rely on two-dimensional gel electrophoresis to detect the protein with a pI of 4.6; however, this does not readily allow for multiple samples to be simultaneously and rapidly processed. Here we utilize the acid solubility of MARCKS to develop a novel extraction procedure. MARCKS was found to be soluble in 40% acetic acid and can be extracted quantitatively and rapidly from phosphorylation mixtures in vitro or from labeled intact cells. Acetic acid has the advantage that it is volatile and readily removed and precipitates protein in the presence of SDS, and the extracted protein is more readily resuspended in sodium dodecyl sulfate (SDS) sample buffer. Two extraction methods were developed, one for extraction of MARCKS from [gamma-32P]ATP-labeled subcellular fractions or intact synaptosomes labeled with 32Pi and one for extraction from 32Pi-labeled cultured nucleated cells, the latter requiring an additional protein recovery and DNA removal step. With this procedure MARCKS phosphorylation in intact synaptosomes was shown to be reversibly stimulated upon depolarization and MARCKS phosphorylation was found to be an early event in the activation of cultured smooth muscle cells by angiotensin II.

Acetates↗
PubMed1993

The 'oddball CNV' as an indicator of different information processing in patients with panic disorders.

In previous studies we found an inverse relationship between CNV amplitude and the probability of the occurrence of the warning stimulus (S1) in a cued reaction time task. The aim of the present study was to investigate this 'oddball effect' on CNV amplitude (Oddball CNV) in patients with anxiety disorders, since this effect describes the influence of event probability on reactive as well as proactive components of information processing. Patients suffering from panic disorders with or without agoraphobia and controls participated in a choice reaction time experiment. The subjects' task was to respond to flashes (S2s), cued 4 s in advance in random order by one of two easily distinguishable acoustic stimuli (S1a, S1b). In condition 1 the probability of S1a and S1b was 0.2 and 0.8, respectively, and in condition 2 0.5 for both S1s. The DC-EEG was recorded from F3, F4, C3, Cz, C4 and P3, linked mastoids as the reference. The data obtained confirm the oddball effect on the CNV amplitude, show clear deviations of patients in this effect, and also indicate remarkable differences in CNV shape between patients and controls. These observations are discussed as differences in information processing and information utilization.

Adult↗
PubMed1991

High incidence of esophageal motor disorders in consecutive patients with globus sensation.

Thirty consecutive patients with globus sensation who were referred to a psychosomatic clinic prospectively underwent otolaryngological, videokinematographic, and manometric examinations of pharynx and esophagus to evaluate whether morphological abnormalities or motility disorders underlay their symptom. When indicated by findings, 24-hour pH-metry, scintigraphy of bolus transport, and esophagogastroscopy were performed. Seven patients were shown to have achalasia, 10 had "hypochalasia" (lower esophageal sphincter relaxation less than 75% with esophageal contraction abnormalities but no complete distal aperistalsis), and 1 had diffuse esophageal spasms; 2 patients had also hyperplastic lingual tonsils, 1 had tonsillitis, and 1 had a cervical spondylophyte. Nutcracker esophagus and nonspecific contraction abnormalities were found in 7 patients, and gastroesophageal reflux with esophagitis and a low lower esophageal sphincter resting pressure was found in 1; only 3 patients had normal esophageal motility. None had volunteered dysphagic symptoms at primary evaluation. Psychometric investigations in consenting patients showed no higher mean scores for state and trait anxiety, depression, hysteria, and hypochondriasis than in general medical outpatients. Esophageal motor disorders may, before giving rise to dysphagia, be sensed more vaguely and induce the globus sensation. However, only disappearance of the sensation after treatment allows inferring an etiological significance of such a disorder.

Adult↗
PubMedDate not supplied

Self-complementary oligodeoxyribonucleotides incorporating L-related isodeoxynucleosides: synthesis, physical characterization, enzymology, and CD studies.

The synthesis of self-complementary oligodeoxyribonucleotides (14-16, 18) incorporating the L-related isodeoxynucleotides, isodA (1) and/or isodT (2), is described. For this purpose, the fully protected phosphoramidite building blocks 10 and 12 were synthesized. The conceptually new oligomers exhibit high resistance towards exonucleases. Temperature- and concentration-dependent CD spectral data and accompanying thermodynamic parameters of the oligomers show that isodA-isodT or mixed dA-isodT/isodA-dT base pairs participate in duplex stabilization.

Chemical Phenomena↗
PubMedDate not supplied

Novel propargylamine-linked nucleosides for high throughput SNP genotyping by MALDI-TOF MS.

The synthesis of positively charged and mass tagged nucleosides containing a quaternary ammonium functionality within the penultimate position of a primer is described. Neutralization of the sugar/thiophosphate backbone by alkylation increases the detection sensitivity in the mass spectrometric analysis by a factor of at least 100. The variable introduction of these novel compounds within the extension primers enables flexible design of multiplex genotyping reactions.

DNA↗
PubMedDate not supplied

Genosnip: SNP genotyping by MALDI-TOF MS using photocleavable oligonucleotides.

A photocleavable o-nitrobenzyl CE phosphoramidite building-block was synthesised and incorporated within oligonucleotides. After allele-specific primer extension, desalting was performed using genostrep purification plates. Release of the SNP information containing part through photocleavage created shortened molecules that are easily accessible for MALDI-TOF analysis. Additionally, incorporation of mass modified nucleosides enables flexible design of multiplex genotyping.

Factor V↗
PubMedDate not supplied

Influence of HIV-infection on the Karnofsky score and general social functioning in patients with hemophilia.

Quality of live, defined by different models, has become a major focus of research in chronic disorders. Patients with hemophilia have been found to suffer seriously from the impact of HIV infection. To compare the impact of HIV infection on HIV-positive and HIV-negative patients, we evaluated a group of 60 patients, 30 being positive and 30 negative, suffering from hemophilia, using the Karnofsky index of functioning besides more general social and clinical data. Most patients (n = 53) suffered from hemophilia A. The mean Karnofsky score decreased from 65.22 to 63.43 in the HIV-infected group between 1988 and 1991, but increased from 77.7 to 82.2 in the HIV-negative group; differences were not significant, though differences were significant between the HIV-infected and HIV-negative groups. The Karnofsky score remained constant or increased in 26 (86.6%) of the HIV-negative patients, in contrast to 50% in the infected group. Seven patients, all from the infected group, had died in 1991. The initial Karnofsky score was not a prognosticator of survival. The group as a whole was socially well integrated. Consequently, the Karnofsky score can be a useful instrument in evaluating the global quality of live in HIV-infected patients, though a careful evaluation of results is necessary and a low initial score does not predict survival.

Adolescent↗
PubMedDate not supplied

Capgras syndrome and functional psychosis in 2 survivors of torture.

Functional psychosis has only rarely been described in context with extreme stressors, most studies focusing singularly on posttraumatic stress disorder symptoms. We report for the first time the case histories of 2 patients suffering from Capgras syndrome along with schizoaffective disorder and posttraumatic stress disorder after prior experience of prolonged torture. Interaction of personal life experience and psychiatric disorder are proposed as factors resulting in persistent changes in perception and affect.

Adult↗
PubMedDate not supplied

Psychological disorders in survivors of torture: exhaustion, impairment and depression.

Post-traumatic stress disorder (PTSD) has been described as the characteristic sequel to extreme events in life such as war and especially torture. This limitation to a single approach in regard to diagnosis and treatment has been criticised as being a too narrow concept to describe the effects following extreme events in life, especially as most studies so far were limited to PTSD and a small range of symptoms or disorders. The study presents data on psychiatric disorders in a group of exiled survivors of torture presenting to an out-patient department for psychiatry. A DSM-III-R-based psychiatric interview, including the general assessment of functioning scale (GAF), an open list of symptoms and the Vienna diagnostic criteria in regard to depression were used to evaluate a broader range of possible sequels. The most frequent present diagnosis in 44 patients seen over a period of 3 years was PTSD (n = 40), but criteria for a present diagnosis of other disorders were fulfilled in 34 patients, even years after torture, mainly major depression or dysthymia (n = 26). Criteria for functional psychosis were fulfilled in 4 patients. Many patients reported symptoms not assessed by DSM-III-R criteria, including feelings of shame and guilt, and ruminations on existential fears. The impairment as indicated by the GAF (mean 59.1) correlated best with the presence of the endogenomorphic-depressive axial syndrome, but not with duration of imprisonment, age or other factors. Research on sequels to extreme trauma should not be restricted to a simple diagnosis of PTSD, but should continue to look for a broader conceptualisation, including neglected categories like the axial syndrome, as PTSD is common, but might not be the only factor of importance for research and treatment. ICD-10 might offer a more adequate interpretation of sequels.

Adult↗
PubMedDate not supplied

Guilt and depression: a cross-cultural comparative study.

Although nearly a century has passed since Kraepelin's investigations in Java [Cbl Nervenheilk Psychiatr 1904; 27:468-469], one crucial question regarding guilt in the course of depression has still not been decided: Is there a more or less stable connection independent of culture, or is guilt confined to certain civilisations? This study investigated this issue in 100 Pakistani and 100 Austrian out-patients diagnosed with 'major depression' according to DSM-IV by means of standardised instruments (Schedule for Affective Disorders and Schizophrenia-Life Time Version, Hamilton Rating Scale for Depression, 21-item version). The experiences of guilt were subdivided into ethical feelings (ethical anxiety and feelings of guilt) and delusions of guilt. It turned out that ethical feelings could be found in both cultures regardless of age and sex. They seem to be primarily related to the extent of depressive retardation. However, the distribution of the two subsets of ethical feelings was culture dependent. Delusions of guilt were confined to patients of the Austrian sample. So, our data qualify the exclusivity of the aforementioned two points of view and support the need for a psychopathologically differentiated approach.

Adult↗