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Biomedical subjects

G Ritter

Publications and source records attributed to G Ritter.

At least 109 records · Page 6Linked to original sources
PubMed1989

Characterization of IgG and IgM antibodies induced in melanoma patients by immunization with purified GM2 ganglioside.

The ganglioside GM2 is a differentiation antigen expressed on the cell surface of human malignant melanomas and other cancers of neuroectodermal origin. We have previously reported that immunization with purified GM2 combined with Bacillus Calmette-Guérin as adjuvant and pretreatment with low-dose cyclophosphamide induced production of antibodies against GM2 in five of six patients. We have now extended our study and analyzed the induced antibodies against GM2 were not detected. After immunization, high-titer IgM antibodies were induced in 17 of 24 patients, and high-titer IgG antibodies in eight cases. Additional treatment of 12 patients with cimetidine, a histamine H2 receptor antagonist reported to have antisuppressor cell activity, had no effect on GM2 antibody titers. Antibodies against asialo-GM2 were present in all patients, and antibodies against GM1 were present in 33% of patients, before and after immunization. Antibodies induced by immunization were specific for GM2, though some reacted predominantly with N-acetylneuraminic acid GM2 (GM2), and some reacted with GM2 and N-glycolylneuraminic acid GM2(NeuGcGM2). The pattern of reactivity with GM2 is consistent with the response to T-cell-independent antigens: both IgM and IgG antibody responses against GM2 were short lived; peak titers seen after initial and secondary vaccinations were similar; and delayed-type hypersensitivity responses to skin test challenges with GM2 were not detected in any patients. However, the IgG response typed as predominantly IgG1 and IgG3, not IgG2 as might be expected for carbohydrate antigens (which are generally T-cell-independent antigens). Because IgG1 and IgG3 antibody responses are usually to T-cell-dependent antigens, the humoral immune response elicited by GM2 vaccination has both T-cell-dependent and T-cell-independent characteristics. These IgM and IgG responses against this neuroectodermal differentiation antigen expressed on melanoma cells have been induced without evidence of neurological or other toxicity.

Antibodies↗
PubMed1989

Antibody response after immunization with the gangliosides GM1, GM2, GM3, GD2 and GD3 in the mouse.

The gangliosides GM2, GD2 and GD3 are differentiation antigens expressed on the cell surface of human melanomas and other cancers of neuroectodermal origin. We have compared the antibody response after vaccination with gangliosides GM1, GM2, GM3, GD2 and GD3 in the mouse. Purified gangliosides were injected subcutaneously alone or attached to Salmonella minnesota mutant R595 after pretreatment of the mice with low-dose cyclophosphamide. Spontaneous GM1 antibodies, but not antibodies against the other gangliosides, were detected in many mice, the incidence increasing with age. Purified gangliosides injected alone (in saline) induced no antibody response. R595/GM1 and R595/GD3 vaccination induced consistent high-titer antibody responses. R595/GM2 and R595/GD2 induced occasional antibody responses, and R595/GM3 induced no antibody response. Comparison of the antibody responses induced against these gangliosides in the mouse with those in man reveals that GM1, GM3 and GD2 have a similar immunogenicity in both species while the relative immunogenicity of GM2 and GD3 is reversed. To understand better the basis for these differences, the antibody responses against the five gangliosides in man and the mouse were compared with their known expression in normal tissues. No correlation was detected between ganglioside expression in normal brain and immunogenicity, consistent with this being a cloistered site. The antibody responses did correlate inversely with expression in normal non-brain human and murine tissues. Variations between species of ganglioside immunogenicity may reflect variations in ganglioside expression in normal tissues.

Animals↗
PubMed1989

[Ligament lesions of the knee joint in childhood].

As a matter of principle, all lesions of the knee associated with haemarthrosis must be examined for internal injuries. Ligament ruptures are rare; usually, there are bony ligament tears that show up on x-ray film. Examination of ligament stability in children is useful only if the x-ray is negative and after the knee joint has been punctured under anaesthesia, and can be justified only in that case. Diagnosis is possible only by means of x-ray films taken in forced extreme joint position in two planes, with lateral comparison. Treatment of all non-dislocated ligament tears is conservative; slight dislocations can be tolerated in cruciate and capsular ligaments, since the epiphyseal cartilage is not affected. Surgery should be performed only if tears are considerably dislocated. Proximal tears of collateral ligaments are epiphyseal fractures that can be treated conservatively only if there is no dislocation; if they are dislocated, surgery is absolutely mandatory.

Child↗
PubMed1989

Bone grafting in total hip replacement. Preliminary results with MRI.

MRI of ten hip joints in nine patients with total hip replacement and reconstruction of the acetabulum with autologous bone grafts, were reviewed. The viability of inserted bone grafts was clearly documented by MRI. Characteristic differences in signal intensity between autologous and homologous bone grafts are discussed. Despite extended metallic artifacts in the operated region, sufficient diagnostic information was available in most cases. No side effects were reported.

Aged↗
PubMed1988

Predictive value of ventricular arrhythmias in resuscitated out-of-hospital cardiac arrest victims.

Twenty-four hour ambulatory electrocardiograms recorded in 103 survivors of out-of-hospital cardiac arrest were analyzed to find those characteristics of the ventricular premature complex (VPC) which provide the best combination of sensitivity, specificity, and predictive accuracy for subsequent mortality. VPC characteristics were grouped as: (1) frequent (greater than or equal to 25 h-1), (2)bigeminal, (3) multiform, (4) early coupled, (5) pairing, (6) repetitive greater than or equal to 2, (7) repetitive greater than or equal to 3, (8) repetitive greater than or equal to 6, (9) the combination of frequent and repetitive, or (10) complex defined as any multiform, early, bigeminal or repetitive VPC. In an average follow-up period of 43 months, 42 deaths occurred, 17 of which were classified as sudden. Each characteristic was a significant predictor for all causes of subsequent death except early coupled VPCs and repetitive VPCs greater than 6. None of the characteristics reached significance as predictors for sudden death. The number of repetitive VPCs when stratified to none, greater than or equal to 2 and greater than or equal to 3 successive VPCs correlated with mortality in an incremental fashion. The combination of frequent VPCs and repetitive VPCs provided the best combination of sensitivity, specificity and predictive accuracy for death from all causes within five years.

Arrhythmias, Cardiac↗
PubMed1988

Clinical characteristics and survival experience of out-of-hospital cardiac arrest victims without coronary heart disease.

Of 270 patients successfully resuscitated from out-of-hospital cardiac arrest, 16% had no evidence of coronary heart disease. In these 43 patients, other forms of heart disease were found in 81% (35/43): cardiomyopathy in 18 patients, valvular disease in six, congenital heart disease in two, and primary arrhythmia in nine. Seven patients had evidence of only pulmonary disease and one had pancreatitis as his precipitating event. Nineteen of the 43 patients (44%) had serum potassium less than 3.6 mEq l-1 in the initial blood sample after cardiac arrest. One- and two-year mortalities were 30% and 43%, respectively, for the group, which is similar to one-year (20%) and two-year (35%) mortalities of the 227 resuscitated patients with coronary heart disease. Patients who survive a sudden death experience and who have no evidence of coronary artery disease are a unique but heterogeneous group who usually have identifiable cardiac or pulmonary disease.

Cardiac Complexes, Premature↗
PubMed1988

Inhibitory effect of nicotine on benzo(a)pyrene elimination and marked pulmonary metabolism of nicotine in isolated perfused rat lung.

Concomitant administration of nicotine to the perfusion medium of an isolated perfused rat lung decreased the pulmonary elimination of benzo(a)pyrene entering the lung by vascular access. This inhibitory effect of nicotine was observed at a concentration of 0.5 microM nicotine in the perfusion medium. The elimination half-life of benzo(a)pyrene given as a bolus to establish an initial concentration of 1 microM in the perfusate was increased by a factor of about 3 after the addition of nicotine at 60 min of perfusion. A comparably high increase of the benzo(a)pyrene steady-state concentration was observed during constant infusion experiments when nicotine as the interfering substrate was infused parallelly after a control period of 60 min. In perfused rat lungs the rate of metabolism of nicotine given as a bolus (initial concentration of 0.5 microM) was comparable to the rate in isolated rat livers for 5,6-benzoflavone, oil or saline pretreated animals. Induction of cytochrome P-450 by pretreatment of the rats with phenobarbital caused an eightfold increase of the nicotine clearance in isolated livers, whereas the pulmonary nicotine clearance was almost doubled. Overall, expressed per g organ weight, the isolated perfused rat lung exhibited a marked capacity to metabolize nicotine while even the maximally induced phenobarbital-stimulated rat liver reached only 60% of the corresponding clearance values (per g organ) of the isolated rat lung. For the 5,6-benzoflavone and control treatments, values of 14%-21% were estimated for the liver compared with lung.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

[Results of treatment following management of tibial segmental fractures].

Between 1965 and 1982 68 patients with segmental-fracture of the tibia have been treated at the Department of Traumatology of the University of Mainz. These patients and their medical records have been investigated. The segmental-fracture of the tibia is characterized by a high percentage (56%) of open injuries and a large amount (11.5%) of bad results. The main problem is the open fracture with major soft tissue injuries. The results of our investigations show, that the degree of soft tissue involvement has a large influence on healing. Because of the critical blood-supply of the tibia and the major circulatory impairment in segmental fractures nailing with a thin nail is a good treatment. In open fractures with major soft tissue injuries the external fixator should be preferred, because it doesn't cause additional soft-tissue-injury.

Adult↗
PubMed1987

Glycosphingolipid composition of human semen.

Glycosphingolipids were extracted from human semen and purified. Based on the fluorometric assay of sphingosine, in spermatozoa a content of 4.4 +/- 0.9 nmol/10(8) cells of gangliosides and 22.1 +/- 1.7 nmol/10(8) cells of neutral glycosphingolipids was determined. Seminal plasma contained 4.1 +/- 0.6 nmol gangliosides and 29.3 +/- 1.5 nmol neutral glycosphingolipids per milliliter. The glycosphingolipid component patterns of human spermatozoa and seminal plasma were determined by thin-layer chromatography. Four neutral glycolipids were isolated and their carbohydrate moieties were characterized. All of these glycolipid components belonged to the globo-series. Gas chromatography, combined gas chromatography/mass fragmentography, and exoglycosidase treatments revealed the following structures for the glycosphingolipids of human semen: Glc1-Cer, Gal beta 1-4Glc1-Cer, Gal alpha 1-4Gal beta 1-4Glc1-Cer, and Gal-NAc beta 1-3Gal alpha 1-4Gal beta 1-4Glc1-Cer. In addition, the occurrence of trace amounts of lactoneotetraosyl- and lactoneohexaosylceramide was detected by immunostaining after thin-layer chromatographic separation. Human spermatozoa, as well as seminal plasma, contained the gangliosides Glac1,Glac2, a sialolactoneotetraosylceramide, and a sialolactoneohexaosylceramide. The gangliosides were identified on the basis of their running characteristics by high-performance thin-layer chromatography, exoglycosidase treatment, and immunostaining after thin-layer chromatography. The ceramide composition of the glycolipids in human spermatozoa, as well as in seminal plasma, was dominated by C22:0-behenic acid and the saturated sphingoid d18:0, sphinganine.

Chromatography, Ion Exchange↗
PubMed1987

[31-phosphorus spectroscopy of osteogenic sarcoma. Possibilities in therapy control in comparison with imaging methods].

31-phosphorus spectroscopy was used to control the results of chemotherapy in a patient with an osteogenic sarcoma. The findings were compared with conventional imaging methods (DSA, MRT and conventional radiography). The imaging methods do not provide reliable information regarding growth of tumour tissue during treatment, whereas the determination of phosphate concentration in the tumour provides direct information concerning tumour metabolism.

Adolescent↗
PubMed1987

[Potentialities of MR tomography in monitoring the therapy of malignant bone tumors].

The value of MRI as a method for controlling treatment quantitatively was studied in four osteosarcomas and one Ewing sarcoma. Histologically proven change resulting from chemotherapy (2 patients) correlated with a significant increase in T2 of tumour tissue. In three other patients who did not respond to therapy, no change could be demonstrated. MRI appears to be valuable as a non-invasive method for monitoring treatment.

Adolescent↗