Search PubMed⌕ Search

Biomedical subjects

B Schmitz

Publications and source records attributed to B Schmitz.

At least 181 records · Page 10Linked to original sources
PubMed1979

Relationship between histocompatibility antigens, other surface determinants and the IgE receptor on rat mast cells.

Rat alloantibodies recognizing classical transplantation antigens (CTA) or non-H-1 determinants were able to compete effectively with monomeric IgE or IgG-coated sheep erythrocytes for receptor sites on the rat mast cell surface. Inhibitory capacity, however, was entirely confined to anti-CTA antibodies of the IgG2a subclass, whereas IgG1 antibodies lacked this ability. Analogously, F(ab')2 fragments of anti-CTA antibody consistently failed to affect IgE binding, but exposure of cell-bound F(ab')2 to anti-rat IgG restored its inhibitory capacity. From these results it was concluded that receptor sites recognizing the Fc portion of the anti-CTA molecule are involved in the inhibition process. Based on a cytotoxicity assay and on comparative absorption studies on alloantisera, the existence and relative amount of CTA and I region-associated antigens on purified rat mast cells and lymph node cells were analyzed. Whereas the CTA concentration per unit surface area on both cell types was very similar, rat mast cells consistently lacked Ia antigens.

Absorption↗
PubMed1977

Positional isomers of unsaturated fatty acids in rat liver lipids.

The fatty acids of liver lipids from rats raised on a fat free diet from the 30th to the 90th day after birth were analyzed with special regard to the detection of positional isomers of mono-, di-, tri-, and tetraenoic fatty acids. The methyl esters obtained after transesterification of total lipids were separated by argentation chromatography into five fractions: I saturated, II monoenoic, III dienoic, IV dienoic nonmethylene interrupted, V tri- and tetraenoic fatty acid esters. After hydroxylation of the double bonds with osmium tetroxide, the analysis of the poly-O-trimethylsilyl derivatives by gas liquid chromatography on S.C.O.T. columns combined with mass spectrometry revealed the presence of 19 monoenoic, 15 dienoic, and 9 trienoic as well as 3 tetraenoic fatty acid isomers including the normally occurring representatives of the (n-3), (n-6), (n-7), and (n-9) fatty acid families. The majority of the identified isomers can be coordinated to one of these families like 7-16:1; 11-20:1; 6,9-18:2; 8,11-20:2; 5,11-20:2; 5,8,11-20:3; 7,10,13-22:3 to the (n-9) family, 11-18:1; 13-20:1; 5,11-18:2; 7,13-20:2; 6,11-18:2; 6,9-16:2; 8,11-18:2; 10,13-20:2; 5,8,11-18:3; 7,10,13-20:3; 4,7,10,13-20:4 to the (n-7) family and 11,14-20:2; 5,11,14-20:3; 6,9,12-18:3; 8,11,14-20:3; 5,8,11,14-20:4; 7,10,13,16-22:4 to the (n-6) family. All these naturally occuring isomers can be placed into a network of desaturation and chain elongation steps which allows certain conclusions about the substrate specificity of the delta6-, delta5- and delta4-desaturase systems. The great number of isomers found in the (n-7) family indicates that the members of this family are actively metabolized in partial essential fatty acid deficiency.

Animals↗
PubMedDate not supplied

[Bone density measurements of the proximal femur in relation to torsion of the femoral neck].

The DEXA-method allows for bone mineral density measurements of different regions of the skeletal system. It is known that results obtained from the spine with this two-dimensional method may be biased in cases of spondylosis, spondylarthritis, and compression fractures; similarly biased results can be expected at the proximal femur due to morphometric peculiarities. The influence of anteversion and rotation of the femoral neck has been investigated in the present study. The results indicate that errors due to rotation as occurring in incorrect positioning or in arthrogenic variabilities mainly have effects on measurements of Ward's triangle: The average measurement error at 20 degrees external rotation amounts to 33.8% with a maximum of 66.5%. Measurements of the trochanteric region and of femoral neck region show a variation of 6.2% and 9.7%, respectively.

Absorptiometry, Photon↗
PubMedDate not supplied

[5-10-year results with the straight-shaft Müller prosthesis].

103 patients with 106 Müller straight stem prostheses could be evaluated clinically and radiologically after an average follow-up period of 6.8 years (range 5 to 10 ys.). Although until now no revision for aseptic loosening has become necessary 3 p.c. of the stems and 11 p.c. of the acetabular components showed radiological loosening. The clinical results were rated as satisfactory. After surgery 67 p.c. of the patients were completely painfree, 28 p.c. still had slight pain, 4 p.c. moderate and 1 p.c. severe pain. The investigation concentrated particularly on radiographic changes of the interface of the femur. Whereas radiolucency typically was non-progressive and located in the proximal part of the femur we found an increasing atrophy of the cortical bone on the calcar. Moreover, we found a continuous and increasing subsidence of the stem during the whole period of observation. At the time of follow up 56 p.c. of the straight stems had subsided about 2 mm and more. Calcar atrophy and radiolucency were significantly less present in femurs with a tapered medullary canal than in those with a cylindrical shape.

Acetabulum↗
PubMedDate not supplied

[Transverse skeletal axes of the lower extremity in coxarthrosis].

Femoral anteversion, anteversion of the acetabulum and tibial torsion of 47 patients with idiopathic osteoarthritis of the hip were determined by computerized tomography. From all these parameters only the anteversion of the acetabulum showed differing values in hips with and without osteoarthritis. There was a considerable range at the individual measured values in all parameters and differences between the male and female groups could be found in femoral anteversion and anteversion of the acetabulum.

Biomechanical Phenomena↗
PubMedDate not supplied

[Lateralization of the femur head--its significance for the pathogenesis, diagnosis, therapy and course of Perthes' disease].

Lateral displacement of the femoral head was measured by the radiographs of 71 patients suffering from Perthes' disease. It is reported to be an early sign of the disease. Also it represents subluxation of the head of the femur, which is well accepted for a not favourable outcome. At the time of diagnosis average widening of the medial joint space was 1.9 mm. During the course of the disease the joint space was at its maximum width during fragmentation stage. A relation between lateral displacement and the extent of the disease could be shown, what suggests an importance in pathogenesis. Swelling of the soft tissues within the fossa acetabuli has been related to lateral displacement. On abduction films the femoral head could be demonstrated to migrate deeper into the acetabulum in those cases, when flattening of the femoral head was present. The consequences for the course and therapy of the disease is discussed.

Child↗
PubMedDate not supplied

Hippocampal activations during repetitive learning and recall of geometric patterns.

Hippocampal activation is required for episodic memory. Encoding and retrieval of novel and memorable items have been related to different locations in the hippocampus; however, the data remain ambiguous. The application of a newly designed keyboard allowed investigation of brain activation during encoding and free immediate and delayed recall with functional magnetic resonance imaging (fMRI) in young healthy controls (n = 12). Because of the repetitive learning and recall conditions, an individual learning gradient was used to contrast neural activity at different individual levels of novelty. During learning, subjects were asked to memorize 10 geometric patterns requiring the establishment of intra-item associations for memorization. After learning, subjects were asked to recall the items actively via the keyboard. Learning and recall were alternated five times. Delayed recall was scanned about 15 min after the fifth immediate recall condition without subjects having seen the items again. Left-sided anterior hippocampal activity was observed during conditions of initial learning as well as maximum recall. Neural activity during delayed recall did not reveal hippocampal responses and was characterized by a transition of neural activity from occipitoparietal regions to bilateral temporal cortices. We conclude that both lateralization and segregation depend on the specific relational characteristics of the stimuli requiring establishment of intra-item associations for encoding as well as retrieval. The absence of hippocampal activation during delayed recall together with the increase of lateral temporal involvement possibly corresponds with an emerging transition from episodic to long-term memory.

Adult↗
PubMedDate not supplied

In vivo and in vitro effects of glucocorticoids on lymphocyte proliferation in man: relationship to glucocorticoid receptors.

Interrelations between the hypothalamic-pituitary-adrenal system (HPA) and the immune system represent a well-documented biological phenomenon. While in vitro administration of glucocorticoids may inhibit concanavalin A (Con A)- and phytohemagglutinin (PHA)-induced T-cell proliferation, pokeweed mitogen (PWM)-driven B-cell mitogenesis is relatively resistant to glucocorticoids. To further explore the link between the HPA and the immune system in relation to glucocorticoid receptor function, dose-response curves were obtained for Con A- and PHA-induced T-cell mitogenesis, PWM-generated B-cell mitogenesis and spontaneous lymphocyte proliferation in 13 healthy controls. Glucocorticoid effects were assessed in vivo by depletion of endogenous glucocorticoids after oral administration of 1.5 g metyrapone (MET) and subsequent glucocorticoid replacement, and in vitro by incubation of the cells with different doses of dexamethasone (DEX). There was a significant decrease in PWM-induced B-cell mitogenesis and a more pronounced effect of DEX administered in vitro on spontaneous lymphocyte proliferation after MET treatment when compared with the DEX plus MET pretreated condition in vivo. These data suggest that the inhibition of spontaneous lymphocyte proliferation by glucocorticoids in vitro is related to glucocorticoid receptor function. The decrease in PWM-generated B-cell proliferation following cortisol depletion by MET may be seen in connection with impaired glucocorticoid-mediated induction of interleukin-1 receptor synthesis.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

[EMG-controlled postoperative exercise therapy using the ELMOBIL].

On the basis of clinical cases, the application possibilities of a newly developed portable EMG amplifier in the field of physiotherapy. The device permits continuous recording of the EMG activity of the muscles requiring therapy over any desired period of time.

Adult↗
PubMedDate not supplied

Evaluation of focal epilepsy: a SPECT scanning comparison of 123-I-iomazenil versus HM-PAO.

PURPOSE: To establish whether regional disturbances of the benzodiazepine receptor distribution in focal epilepsies can be detected by SPECT using 123-I-Iomazenil. PATIENTS AND METHODS: Benzodiazepine receptor imaging was carried out in 10 patients interictally. To be eligible for this study the patients had to have a history of focal seizures and no evidence of routine imaging abnormalities as in CT or MR. The patients were selected on the basis of a regional decreased blood flow in HMPAO SPECT that correlated with the site of a stable unifocal EEG abnormality. Benzodiazepine receptor imaging was performed after intravenous administration of approximately 110 MBq 123-I-Iomazenil using SPECT. RESULTS: A regional reduced activity was found on sequential SPECT series after 30 and 90 min post injection in the receptor study. The brain region with a reduced receptor density was concordant to the pathologic finding in HMPAO SPECT in all patients. CONCLUSION: For the evaluation of patients with focal epilepsies lomazenil SPECT offers several advantages over HMPAO SPECT. Iomazenil binds specifically to the benzodiazepine receptor complex whereas the exact binding sites of HMPAO are still unknown. In contrast to HMPAO, lomazenil can be used for sequential SPECT examinations that may detect dynamic changes of the receptor complex. For the purpose of benzodiazepine receptor imaging, lomazenil is a suitable ligand in patients with focal epilepsies.

Adult↗