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Biomedical subjects

G Fischer

Publications and source records attributed to G Fischer.

At least 415 records · Page 23Linked to original sources
PubMed1988

Somatostatin does not reduce oesophageal variceal pressure in liver cirrhotics.

Transmural oesophageal variceal pressure was determined by direct puncture of the varices in 27 patients with liver cirrhosis and oesophageal varices. Variceal pressure was not influenced three to six minutes after somatostatin bolus administration and slightly increased during somatostatin infusion. Thus, potential haemostatic benefits of somatostatin cannot be explained by pressure reductions in the varices.

Blood Pressure↗
PubMed1988

Three injections of human chorionic gonadotropin are as effective as ten injections in the treatment of cryptorchidism.

Two schedules of human chorionic gonadotropin (hCG) administration were compared in a study of 332 boys (473 testes) aged 1-13 years with cryptorchidism. One group of patients received 10 hCG injections according to the International Health Foundation (IHF) schedule while the other group received 3 hCG injections at intervals of 7-10 days (1-3 years = 3 x 1,000 IU; 3-6 years = 3 x 1,500 IU; 6-10 years = 3 x 3,000 IU; 10-13 years = 3 x 5,000 IU hCG). Results from both schedules were comparable during the first and also during a second treatment period at the age of 1-3 and 3-6 years; between 6 and 13 years of age the IHF schedule was more successful.

Age Factors↗
PubMed1988

Epidermoid cyst of the fourth ventricle.

The case of a 52-year-old patient with a fourth ventricle epidermoid is reported. The initial presentation included long-standing headaches, progressive anomalies of gait and slight impairment of mentation. CT showed a hypodense mass enhancing peripherally after contrast infusion. Brain auditory evoked responses (BAER) showed asymmetric increased latencies. At operation, total removal of an extensive fourth ventricle epidermoid was achieved. A delayed meningitis occurred postoperatively. Physical examination was normal at the 2 year follow-up and BAER were improved. The etiological and clinical features of fourth ventricular epidermoids are briefly reviewed. The diagnostic value of CT is emphasised but the possibility of CT-dense epidermoid cysts deserves a special mention. Total removal of the neoplasm is the theoretical aim of operative treatment, but this purpose may be harmful when the ventricular floor is involved by the capsule.

Brain Diseases↗
PubMed1988

Dipeptidylpeptidase IV--inactivation with N-peptidyl-O-aroyl hydroxylamines.

Eleven N-peptidyl-O-aroyl hydroxylamines have been synthesized and their hydrolytic stability, acidity and properties during reaction with dipeptidyl peptidase IV (E.C. 3.4.14.5) investigated. N-peptidyl-O-(4-nitrobenzoyl) hydroxylamines act as irreversible inhibitors of serine proteases. The serine enzyme, dipeptidyl peptidase IV (DP IV), is inactivated by substrate analog derivatives of this class by a suicide inactivation mechanism. During the enzyme reaction of DP IV with the suicide substrates most molecules are hydrolyzed but some irreversibly inactivate the target enzyme. In contrast to porcine pancreatic elastase and thermitase, DP IV exhibits a high ratio for hydrolysis of the compounds versus inhibition during their interaction with the enzyme. Variation of the leaving aroyl residue lowers this ratio. Variation of the substrate analog peptide moieties of the DP IV-inhibitors increases their ability to inhibit the enzyme to a remarkable extent. Possible reaction pathways are discussed.

Dipeptides↗
PubMed1988

[The electrodynamics of biological processes].

The relations between field-physics and biology are systematically and continuously being inspected. In this paper, the electromagnetic field is taken into consideration, too. An objective point for a biological system of equations corresponding with MAXWELL-equations is given. Therefore processes of the growth and procreation are to be regarded as a unit. A new natural constant called b can be predetermined from field-biology. A triplet of natural constants--c, h, and b--enables a solid connection between physics and biology.

Animals↗
PubMed1988

[Tuberous sclerosis and trigonoseptal tumors].

A series of 9 patients having a tuberous sclerosis associated to a midline ventricular tumour is reported. Microscopically, the presence of giant cells within the lesion is a major characteristic of the disease. The origin of these subependymal giant cells tumours is questionable since astrocytic, neuronal and ependymal features have been noted by several authors providing various denominations. In the literature and in our series as well, the intra-ventricular tumour presented as the initial manifestation of the disease in most of cases, usually with increased intra-cranial pressure symptoms. On CT, the tumour arises in the area of the foramen of Monro and enhances after contrast injection while the other intracranial anomalies of the disease do not enhance. In 8 patients, a direct transcortical transventricular approach was used. 1 patient was treated by shunt only. The results were evaluated according to the degree of the preoperative neuropsychological impairement: there were 3 deaths, 3 "excellent", 2 "fair" and 1 "poor" results. The problem of the surgical indication raises mainly in patients in whom the diagnosis of the tuberous sclerosis is ascertained prior to the diagnosis of the tumour. Since acute C.S.F. blockage or intra-ventricular bleeding may occur during "conservative" treatment, direct approach seems preferable.

Adolescent↗
PubMed1988

[Non-traumatic hypertensive rhinorrhea. Apropos of a case].

Non-traumatic C.S.F. rhinorrhea resulting from hypertensive obstructive hydrocephalus due to an intracranial tumor may constitute the presenting symptom of these affections. The authors report one case of intermittent and positional spontaneous rhinorrhea which was the only sign of a tumor in the pineal region. According to the literature and on the basis of Ommaya's classification of spontaneous rhinorrhea, we emphasize the need to distinguish between ventricular and arachnoid C.S.F leak. This different origins will determine the appropriate (ventricular or lumbar) C.S.F. shunt.

Adult↗
PubMed1988

[Veins in the area of the mesencephalon].

The veins on the surface of the mesencephalon were measured on 100 brain halves. The results of this measurements are discussed with issues of earlier authors.

Cerebral Veins↗
PubMed1987

Determination of the monocyclic beta-lactam antibiotic carumonam in plasma and urine by ion-pair and ion-suppression reversed-phase high-performance liquid chromatography.

A sensitive and selective high-performance liquid chromatography method has been developed for the determination of the new monocyclic beta-lactam antibiotic carumonam in plasma and urine. The method for plasma involves protein precipitation with acetonitrile and removal of lipids with dichloromethane; urine is diluted with buffer. Separation and quantification are achieved using a mobile phase based on either ion-suppression or ion-pair chromatography on a reversed-phase column with UV detection. The limit of determination is 0.5 micrograms/ml plasma, using a 0.5-ml specimen, and 25 micrograms/ml urine, using a 50-microliter specimen. The inter-assay reproducibility is generally better than 4% when an internal standard is used. Since beta-lactam antibiotics may degrade on storage, close attention must be paid to the stability of these drugs in biological fluids; novel measures to prevent degradation on storage are described. The assay has been successfully applied to the analysis of several thousand samples from pharmacokinetic studies, including a study involving patients with impaired renal function.

Anti-Bacterial Agents↗
PubMed1987

The role of conjugation reactions in detoxication.

The role of conjugating enzymes is best understood by looking at the interaction between phase I (mostly cytochromes P-450) and phase II (conjugation) enzymes of drug metabolism. A balance between phase I and II enzymes of detoxication largely determines the disposition to drug toxicity. Reactive electrophilic metabolites, generated by phase I enzymes, are often controlled by GSH-transferases, whereas nucleophilic metabolites such as phenols are controlled by UDP-glucuronosyltransferases (GT) and sulfotransferases. It is more and more recognized that the control of the more stable and more abundant nucleophiles is as important as the control of electrophiles, since the former can be readily converted to electrophiles. For example, phenols and quinols can undergo quinone/quinol redox-cycles with the generation of reactive oxygen species. In the case of benzo(a)pyrene-3,6-quinol toxicity can be prevented by glucuronidation. Conjugating enzymes consist of families of isoenzymes with distinct but overlapping substrate specificity. Rather than dealing with individual isoenzymes, adaptive programs are emphasized by which gene expression of a battery of phase I and II enzymes is turned on by certain types of inducing agents. Mechanistically best known is the program turned on by 3-methylcholanthrene-type inducers which includes enhanced synthesis of certain isoenzymes of cytochrome P-450, GT and probably GSH-transferase. The program may adapt the organism to efficiently detoxify and eliminate aromatic compounds such as benzo(a)pyrene. Evidence is presented that this program exists in both rodents and humans.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

The role of biotransformation in the genotoxicity of allylic compounds.

Allylic compounds exert direct genotoxic activities which depend on the chemical nature of the leaving group and on further substituents. Besides the direct genotoxic effects, metabolic activation mechanisms are also conceivable. Epoxidation seems to play a minor role in bioactivation, whereas the metabolic formation of strongly mutagenic alpha, beta-unsaturated carbonyl compounds is obviously of great importance for the indirect genotoxicity of allylic compounds. Only in the case of 2,3-dichloro-1-propene is an epoxide formed which is extremely unstable and immediately rearranges to the strong mutagen, 1,3-dichloroacetone.

Allyl Compounds↗
PubMed1987

Prediction of therapeutic response in acute treatment with antidepressants. Results of an empirical study involving 159 endogenous depressive inpatients.

A study was carried out involving 159 endogenous depressive inpatients treated with antidepressants. Using standardized rating instruments, a large set of potential predictor variables was tested. After cross-validation according to the split-half technique, only very few of these proved to be suitable as predictors for the main outcome criteria. These predictors included premorbid maladjustment, neurotic traits of premorbid personality, intensity of depressive-apathetic symptoms at admission, and the self-evaluated mood assessment score 3 weeks after commencement of treatment. This last criterion demonstrated the highest predictive value. Several predictors known from the literature could not be reproduced in this study.

Adolescent↗