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Biomedical subjects

M M Müller

Publications and source records attributed to M M Müller.

At least 73 records · Page 4Linked to original sources
PubMed1998

Genotype and phenotype of N-acetyltransferase 2 (NAT2) polymorphism in patients with contact allergy.

We investigated whether patients with contact allergy differed from non-contact-allergic, non-atopic controls with regard to genotype and phenotype of the polymorphic enzyme N-acetyltransferase 2 (NAT2). 55 contact-allergic patients recruited from the Information Network of Departments of Dermatology (IVDK) were compared to 85 controls from among local health care personnel. NAT2 activity was calculated from HPLC analysis of the ratio of the caffeine metabolites 5-acetylamino-6-formylamino-3-methyluracil (AFMU) and 1-methylxanthine (1MX) in the urine. NAT2 genotype was determined by polymerase chain reaction (PCR). A statistically significantly increased proportion of rapid acetylators was found in contact-allergic patients. This may have 2 possible implications: acetylation may enhance contact sensitization; or NAT2 status may be a genetic marker for contact sensitizability.

Acetylation↗
PubMed1998

Usefulness of chromogranin A as a marker for detection of relapses of carcinoid tumours.

It is well known that peptide-producing endocrine tumours cosecrete immunoreactive chromogranin A with their characteristic hormones. Into this study 187 patients with the diagnosis malignant carcinoids or other malignancies were entered. Using chromogranin A at a cut-off level of 30.3 U/ml it was possible to discriminate between patients in remission and patients suffering a relapse with a sensitivity of 91.7% and a specificity of 96.4%, which may be of important diagnostic value. In our study that lasted over one year we could clearly show that the measurement of chromogranin A is impressively superior to 5-hydroxyindoleacetic-acid for detecting a relapse of carcinoids.

Biomarkers, Tumor↗
PubMed1997

Visually induced gamma-band responses to coherent and incoherent motion: a replication study.

The present study was based on earlier findings that the observation of a coherently moving long bar induced gamma-band activity in humans. The power in the EEG-gamma-band was reduced during the presentation of two incoherently moving short bars. The present study demonstrates the replicability of this cortical activity pattern and illustrates intersubjective variability in its topography. In addition, cortical alpha-activity was examined to test whether gamma-band activity might reflect changes in harmonics of alpha waves. Results indicate that induced gamma-band activity cannot be secondary to changes in the amplitude of alpha waves, since the latter would require both a similar time course of both frequency bands while stimuli are in motion and an identical topographical pattern. The present results suggest that oscillations in the gamma- and the alpha-bands are two different brain activities, with different functional implications.

Adult↗
PubMed1997

Clinical usefulness of percentage of free serum prostate specific antigen.

Serum concentrations of total and free prostate specific antigen were measured retrospectively in 268 patients, in order to test the usefulness of percentage of free prostate specific antigen in distinguishing between cancer and benign hyperplasia of the prostate and to improve the specificity of cancer screening. Four groups were investigated: 94 urologic patients without prostate disease (controls), 98 patients with a histologically confirmed benign hyperplasia, 76 with histologically established prostatic adenocarcinoma, 18 of them after radical prostatectomy. Total and free prostate specific antigen concentrations were measured in frozen serum, in a retrospective mode, by using an equimolar monoclonal antibody immunoassay. Median percentage of free prostate specific antigen was 20.48% in controls, 17.75% in patients with hyperplasia, 10.52% in patients with cancer and 33.03% in patients after prostatectomy. Median percentage of free prostate specific antigen was significantly lower in men with cancer than in patients with benign hyperplasia (P < 0.0001). The percentage of free prostate specific antigen increased the specificity of cancer screening: a cut-off of 23.6% detected at least 90% of cancers and would have eliminated 34.7% of biopsies in benign hyperplasias. A prospective study is ongoing to confirm these results.

Adenocarcinoma↗
PubMed1997

Magnetoencephalographic recording of steady-state visual evoked cortical activity.

Steady-state visual evoked magnetic fields (SSVEFs) were recorded in response to a flickering light source using a 37-channel magnetometer. The SSVEF had a sinusoidal waveform having the same fundamental frequency as the driving stimulus, which was either 6.0 Hz, 11.9 Hz, or 15.2 Hz. SSVEF topographies at each frequency had a dipoloar form over the posterior head that could well-modelled by single equivalent current dipoles. The best-fit dipoles were localized in posterior occipital cortex for the SSVEFs to 6.0 and 11.9 Hz stimuli and in more anterior and ventromedial occipital cortex for the 15.2 Hz SSVEP.

Adult↗
PubMed1997

IMP-dehydrogenase inhibition in human lymphocytes and lymphoblasts by mycophenolic acid and mycophenolic acid glucuronide.

Inosine 5'-monophosphate dehydrogenase (IMP-DH) activities were measured in human lymphocytes (exhibiting type I IMP-DH activity) and human lymphoblasts (exhibiting type II IMP-DH activity) in the presence of various amounts of mycophenolic acid (MPA) (0-20 mumol/L) and MPA glucuronide (MPAG) (0-200 mumol/L). Moreover, the influences of human serum albumin (HSA) and human plasma on the MPA- and MPAG-mediated effects were investigated. In the presence of water, 2.5 mumol/L MPA decreased the IMP-DH activity measured in lymphocytes by 60%, whereas in lymphoblasts a 80% inhibition was detectable. In the presence of > or = 10 mumol/L MPA, lymphocytic as well as lymphoblastic IMP-DH activities were reduced in a similar manner. The concentration of MPAG required for 50% inhibition was for both cell types > 25 mumol/L and < 50 mumol/L, respectively. MPAG (200 mumol/L) reduced lymphocytic as well as lymphoblastic IMP-DH activity by approximately 80%. With 100 g/L HSA or human plasma as diluent, the inhibitory effects of MPA and MPAG were significantly (P < 0.05) diminished, whereas HSA concentrations < or = 25 g/L only slightly influenced the inhibition of IMP-DH activity by MPA and MPAG. In summary, it can be clearly demonstrated that not only MPA but also MPAG contributes to the inhibition of both IMP-DH isoenzymes, which might be relevant for the immunosuppressive properties of mycophenolate mofetil in transplant patients.

Blood Proteins↗
PubMed1997

[Visually-induced gamma band responses in human EEG- expression of cortical stimulus representation?].

The features of a visual stimulus are processed in different regions of the visual cortex with no direct axonal connections. Therefore, neurons in the distributed processing areas must be connected in some way to form the physiological substrate of the percept. On the basis of theoretical considerations and animal experiments, it has been proposed that synchronization of neuronal oscillatory firing patterns in the gamma band range (above 30 Hz) might be essential in linking the anatomically distant cell assemblies that represent the various features of the stimulus. The present work reports on three experiments in which the functional relevance of induced gamma band responses were investigated in the human EEG. Using an identical stimulation design, as used in animal studies, it was demonstrated that human induced gamma band responses resembled those reported from intracortical recordings from animals. It was further shown that alpha and gamma band activities differed in temporal characteristics as well as in topographical features, indicating the representation of different cortical functional states. In accordance with previous animal and human experimental findings, a complex moving stimulus was related to a suppression of induced gamma band activity as opposed to a standing complex stimulus.

Animals↗
PubMed1996

Visually induced gamma-band responses in human electroencephalographic activity--a link to animal studies.

Visual presentation of an object produces firing patterns in cell assemblies representing the features of the object. Based on theoretical considerations and animal experiments, it has been suggested that the binding of neuronal representations of the various features is achieved through synchronization of the oscillatory firing patterns. The present study demonstrates that stimulus-induced gamma-band responses can be recorded non-invasively from human subjects attending to a single moving bar. This finding indicates the synchronization of oscillatory activity in a large group of cortical neurons. Gamma-band responses were not as apparent in the presence of two independently moving stimuli, suggesting that the neuronal activity patterns of different objects are not synchronized. These results open a new paradigm for investigating the mechanisms of feature binding and association building in relation to subjective perception.

Animals↗
PubMed1996

Effects of voluntary movements on early auditory brain responses.

It has not been clear whether or not early information processing in the human auditory cortex is altered by voluntary movements. We report a movement-related, complex event-related potential consisting of relatively long-lasting amplitude and phase perturbations induced in an ongoing auditory steady-state response (SSR) by brief self-paced finger movements. Our results suggest that processing in the auditory cortex during the first 50-100 ms after stimulus delivery is affected before, during, and after voluntary movements, beginning with a 1- to 2-ms delay in the SSR wave form starting 1-2 s before the movement.

Acoustic Stimulation↗
PubMed1995

Tissue polypeptide specific antigen, neopterin, and CRP for monitoring heart transplant recipients.

OBJECTIVES: The aim of our study was to investigate the usefulness of tissue polypeptide specific antigen, an established tumor marker detecting proliferation of cells, for monitoring heart transplant recipients in order to detect infection and rejection early. METHODS: Tissue polypeptide specific antigen serum levels were compared with neopterin and C-reactive protein serum concentrations. RESULTS: When infections occurred, tissue polypeptide specific antigen serum concentrations were increased approximately five times (mean: 214 U/L, SD 145), while in instances of acute rejection crises, they were increased two times (mean: 76 U/L, SD 16 in comparison with the values during uncomplicated postoperative courses (mean: 45 U/L, SD 26). CONCLUSIONS: Tissue polypeptide specific antigen was the only investigated analyte that showed significant diagnostic validities when infections were compared with rejections. The discrimination between an uncomplicated postoperative course and a rejection or infection episode was only possible with a combination of the three analytes.

Adolescent↗
PubMed1995

The relationship between habitual anger coping style and serum lipid and lipoprotein concentrations.

The relationship between habitual anger coping styles, especially anger expression in a socially assertive manner and serum lipid concentrations was examined in 86 healthy subjects. Habitual anger expression was measured by the Müller Anger Coping Questionnaire (MAQ) on four scales: Aggression, Controlled Affect, Guilt, and Social Inhibition. A positive correlation between serum cholesterol and Aggression was found, as was a negative correlation between LDL/HDL ratio and Controlled Affect. These correlations remained significant after adjustments for age, Body Mass Index (BMI), athletic activity, alcohol, nicotine and coffee consumption. After these adjustments, significant negative partial correlations between Controlled Affect and both total cholesterol and LDL were also found. We found no significant gender differences on any lipid measure. This study demonstrated that unfavourable lipid profiles are linked to a predominantly aggressive anger coping style, whereas favourable lipid profiles are associated with more socially assertive anger coping (Controlled Affect). Thus the expression of anger in a socially assertive manner can be seen as health promoting. The MAQ scales were better predictors of total serum cholesterol concentrations than the health related behaviors and characteristics. Results are discussed in terms of a psychophysiological risk model of inadequate anger coping.

Adaptation, Psychological↗
PubMed1995

Tissue polypeptide specific antigen for the detection of lymphoproliferative diseases induced by cyclosporin.

AIM: To evaluate the efficacy of tissue polypeptide specific (TPS) antigen for the early detection of cyclosporin A (CyA) induced post-transplant lymphoproliferative diseases. METHODS: Serum concentrations of TPS antigen were analysed using a monoclonal enzyme immunoassay and whole blood CyA concentrations were measured using high pressure liquid chromatography. Infection with Epstein-Barr virus and cytomegalovirus was detected by determining levels of IgM and IgG antibodies directed against viral capsid antigen (VCA). Immunohistochemistry and analysis of clonality were carried out on formalin fixed, paraffin wax embedded tissue. RESULTS: The mean serum concentration of TPS antigen in the eight transplant recipients investigated was 60 U/l during periods without complication (control), 101 U/l during infection, 166 U/l when the diagnosis of a lymphoma was confirmed, and 172 U/l when lymphoma and infection coincided. Increased TPS antigen concentrations were detected in six patients one month before detection of malignancy. After reduction of immunosuppression and the start of tumour regression, TPS antigen concentrations decreased. TPS antigen concentrations increased in the one patient who experienced a recurrence. CONCLUSIONS: Continuous monitoring of TPS antigen concentrations leads to the early discovery of CyA induced lymphoproliferative disease.

Adult↗
PubMed1995

Individual reference ranges of CA 15-3, MCA and CEA in recurrence of breast cancer.

The long-term intra-individual variation of the title tumour markers was studied in the group of 33 patients which developed no relapse. The average biological intra-individual CV was 11.2% for CA 15-3 and 14.9% for MCA whereas those of CEA strongly depended on the concentration. The intra-individual standard deviation of CEA was independent of concentration and amounted to 0.23 g/L. Individual reference ranges the analytes were much smaller than the group reference ranges. Individual reference limits were calculated on the basis of the average intra-individual variation. In 21 of the 22 patients who developed recurrence during the follow-up period, individual reference limits of CA 15-3 and/or CEA were exceeded 1 to 31 months (median 10 months) before clinical evidence (diagnostic sensitivity 95%). Group reference limits were exceeded only in 13 patients (diagnostic sensitivity 60%) and occurring later. The diagnostic specificity was 97%. MCA did not provide additional information. The combination of CA 15-3 and CEA is an excellent for detection and exclusion of recurrence in the follow-up of breast cancer patients if decision-making is based on individual reference limits. Improvement of the long-term analytical quality of the tumour marker assays, particularly in the low concentration range is necessary.

Adult↗
PubMed1995

Neopterin: biochemistry and clinical usefulness.

Neopterin is a marker for activation of the immune system. Serum or urine neopterin can increase in infection, transplant rejection, or in other disturbances of the immune system. Measurement of neopterin concentrations in body fluids offers a way to monitor the patient's immune system in some disorders. However, the nonspecificity of this biochemical marker for particular diseases raises problems in the interpretation of the results. This paper discusses the effects of disease and other factors on the levels of neopterin in biological fluids.

Biomarkers↗