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Biomedical subjects

H Schenk

Publications and source records attributed to H Schenk.

At least 55 records · Page 3Linked to original sources
PubMed1990

[The neuraminic acid/protein quotient in amniotic fluid: indicator for fetal maturity].

The concentration of neuraminic acid and proteins was determined in amniotic fluid of 207 pregnancies during the amniocentesis, performed in the 16.-21. week of gestation, 17 prematurities and 101 deliveries in time. The neuraminic acid/protein quotient increases significantly at term. Than, its reference range is 51.3-154.8 mumol/g (2.5-97.5 percentile). The neuraminic acid/protein quotient can be an useful prenatal indicator of the fetal maturity because of its high diagnostic specificity (97%) and sensitivity (88%).

Amniocentesis↗
PubMed1990

Synaptic plasticity in rat medial prefrontal cortex under chronic haloperidol treatment produced behavioral sensitization.

Morphometric analysis of the population of synapses in medial prefrontal cortex (layer VI) of rat treated daily with haloperidol in a dose of 1.0 mg/kg during 3 weeks was performed on the electronmicroscopic level. The density of synapses on dendritic shafts increased on 29% and on the head of spine it increased on 20%. Nearly all the parameters measured in axo-spinous synapses were significantly decreased (area of presynaptic terminal, summarized area of mitochondriae per terminal, number of synaptic vesicles near the active zone, area of postsynaptic spine). There were no differences between the parameters of axo-dendritic synapses in control and haloperidol-treated rats. The data suggest that haloperidol might have induced the formation of the new synapses and may have changed the efficacy of the synaptic transmission in axo-spinous synapses on the head of spine.

Animals↗
PubMed1989

[Abnormal gangliosides in the plasma of alcoholics].

Gangliosides were isolated from plasma of alcoholics. The pattern of gangliosides was compared with that of healthy humans. Up to seven fractions of gangliosides could be detected. In healthy subjects the following pattern was found: GM3 38.2%, SPG 6.0%, GD3 30.2%, GD1a 10.6%, GD1b 4.8%, GT1b 7.9%, GQ1b 2.2%. In alcoholics, significant differences were observed in the main ganglioside fractions GM3 (52.6%) and GD3 (17.5%).

Adult↗
PubMed1989

[Determination of N-acetylneuraminic acid for the differential diagnosis of cystic ovarian tumors].

The concentrations of N-acetylneuraminic acid (NANA) were determined in the fluid of cystic ovarian tumors and in the blood serum from a total of 95 patients. The estimation of NANA was based on the method of Svennerholm. It was found that the mean content of NANA in the cystic fluid is more than 3.0 mmol/l in serous and more than 5.5 mmol/l in mucinous malignant ovarian tumors. The mean value of NANA in the serum of patients is mostly more than 3.5 mmol/l if there is an ovarian cancer. The estimation of NANA is useful for the preoperative diagnosis of cystic ovarian tumors.

Adolescent↗
PubMed1989

The effects of amphetamine on synaptic plasticity in rat's medial prefrontal cortex.

Morphometric analysis of medial prefrontal cortex (layer VI) of rats treated daily with amphetamine in a dose of 2.5 mg/kg during 3 weeks was performed on the electron microscopic level. The efficacy of the amphetamine dosage was tested on behavioral observation. Synapses on dendritic shafts and spines were studied. The density of axo-dendritic synapses increase on 74%, while the density of synapses on spine's neck decreased on 53%. Most synaptic parameters measured in axo-dendritic (1) and axo-spinous (2) synapses increased significantly under the influence of 2.5 mg/kg dose of AMPH: area of presynaptic terminal increased on 35% (1) and 21% (2), length of postsynaptic density increased on 13% (1) and 12% (2), area of spine increase on 25%. But the density of synaptic vesicles near the active zone decrease (1-on 16.5%, 2-on 20%).

Amphetamines↗
PubMed1989

The effects of haloperidol on synaptic plasticity in rat's medial prefrontal cortex.

Morphometric analysis of Medial prefrontal cortex (layer VI) of rats treated daily with haloperidol in a dose of 0.1 mg/kg during 3 weeks was performed on the electron microscopic level. The efficacy of the haloperidol dosage was tested on the amphetamine psychosis model. Synapses on dendritic shafts and dendritic spines were studied. The density of synapses on dendritic shafts increased on 51%, while on spine's neck it decreased on 19%. There were significant changes of some synaptic parameters only in axo-dendritic synapses: area of presynaptic terminal decreased on 13% (p less than 0.05), length of postsynaptic density decreased on 15% (p less than 0.05), but the density of synaptic vesicles near the active zone increased on 10% (p less than 0.05).

Animals↗
PubMed1988

Crystallographic modelling.

The project on crystallographic modelling aims at extending the application of interactive graphics to inorganic structures. Starting from the available expertise in organic and protein modelling, the symmetry of the crystal structure is used not only to draw fixed models of many unit cells of the structure, which as an entity can be interactively manipulated, but also to change details of the structures interactively with retention of the original symmetry. Real-time shifts of atom positions are automatically applied to all symmetry-equivalent atoms given the symmetry constraints. This also applies to translations and rotations of groups of atoms. In order to get feedback about these structural changes one can simulate powder diffraction patterns in real-time mode and compare them with the experimental powder patterns. These features are crucial in truly crystallographic modelling, but have not been implemented before in other programs. The program can be used in combination with standard molecular modelling programs and is also interfaced to the Inorganic Crystal Structure Database. Before describing the realization of these features on state-of-the-art hardware, we will review the expertise in molecular modelling and discuss an MS-DOS program to study inorganic crystal structures.

Computer Graphics↗
PubMed1988

[Abnormal erythrocyte membrane gangliosides in alcoholism].

The pattern of gangliosides in membranes of erythrocytes was examined in healthy donors and in alcoholic subjects. Seven different gangliosides could be detected. In healthy donors the following pattern was found: GM3 = 17.6%, SPG = 43.1%, GD3 = 9.1%, GD1a = 12.8%, FucGD1b = 5.2%, GT1b = 6.7% and GX = 5.7%. The GM3 and FucDG1b fraction were decreased statistically significantly in alcoholics.

Adult↗
PubMed1988

[Ultrastructure of the prefrontal cortex in long-term amphetamine administration].

In animals three weeks of chronic amphetamine administration at 2.5 mg/kg daily doses elicited either functional or dense-type degenerative changes in nerve cells. The former were prevailing, the latter rarely occurred in the single cells. Morphometric analysis showed sharp density increase in axodendritic synapses and density decrease in axospinal ones at the spine's neck. Apart of this, the postsynaptic dense structures were expanded considerably in axodendritic and axospinal synapses. The authors believe this ultrastructural reorganization to result from the amphetamine-elicited dopaminergic hyperfunction.

Amphetamine↗
PubMed1988

Abnormality of gangliosides in erythrocyte membranes of schizophrenic patients.

The pattern of gangliosides in membranes of erythrocytes was examined in healthy donors, in acute schizophrenics without neuroleptic treatment and in alcohol-dependent patients. 7 different gangliosides could be detected. Healthy donors were characterized by the following ganglioside pattern: GX = 5.8%; GT1b = 6.7%; FucGD1b = 5.2%; GD1a = 12.6%, GD3 = 9.2%, SPG = 43.5%, and GM3 = 17.0%. In schizophrenic patients the GM3 and GD3 fractions were increased. No difference was found between the control group and the alcoholics.

Adolescent↗
PubMed1987

[Changes in the gangliosides of erythrocyte membranes of schizophrenic patients].

The pattern of gangliosides in membranes of erythrocytes was examined in healthy donors, in acute schizophrenics without neuroleptic treatment and in alcohol-dependent patients. 7 different gangliosides could be detected after extraction, purification by column chromatography and fractionation by TLC. Healthy donors were characterized by the following pattern of gangliosides: GX = 5.8%, GT1b = 6.7%, FucGD1b = 5.2%, und GD1a = 12.6%, GD3 = 9.2%, SPG = 43.5% and GM3 = 17.0%. In schizophrenic patients the GM3- and GD3-fraction were increased. No difference was found between the control group and the alcoholics.

Adolescent↗
PubMed1987

[Action of haloperidol on the ultrastructure of areas of the dopaminergic system of the brain].

The ultrastructure of the olfactory tubercle was investigated in patients receiving prolonged (3-weeks-long) treatment with low doses (0.1 mg/kg) of haloperidol. This therapy was mostly associated with changes in the neuronal processes and glial cells. It has been found that ultrastructural rearrangement in neurons of the olfactory tubercle is functional in nature which indicates the change in the efficacy of synaptic transmission and in metabolic processes. It is postulated that chronic administration of low doses of haloperidol induces adaptive alterations mediated by DA receptor block.

Animals↗
PubMed1986

Effect of a methylxanthine preparation in the form of a retention enema on pulmonary function and theophylline levels in patients with acute bronchospasm.

The goal of the current study was to determine whether administration of a methylxanthine preparation in the form of a retention enema (theophylline-diprophylline-proxyphylline combination, Neobiphyllin-Clys) has an effect similar to that of intravenous theophylline in the treatment of acute bronchospasm. In a randomized cross-over study 16 patients with a history of asthma were given 0.48 g of theophylline-ethylenediamine (TE) in the form of rapid intravenous infusion or a retention enema containing 400 mg theophylline, 600 mg diprophylline and 600 mg proxyphylline (TDP). Forced expiratory volume in the first second (FEV1) airways resistance (Rt) and serum theophylline levels were determined before administration of the drug and at 15 min, 30 min and hourly for a period of 6 h after administration of the medication. The results were significant at the 5% level. There were significant increases in serum theophylline levels with both TE and TDP. After administration of TE there were significant changes in FEV1 at 15 min and Rt at 30 min which persisted for 5 h after administration of the drug. Statistically significant differences in FEV1 were observed 60 min and in Rt 30 min after administration of TDP. These effects persisted for 6 h. The data document that a retention enema offers the advantage of prolonged action in comparison to intravenous infusion of theophylline in the treatment of acute bronchospasm.

Airway Resistance↗
PubMed1985

Primary intestinal lymphangiectasia in three dogs: a morphological and immunopathological investigation.

Morphological and immunological findings of three dogs with primary lymphangiectasia are described and compared with three normal dogs. Scanning electron microscopy showed distended and fused intestinal villi in dogs with intestinal lymphangiectasia, and morphometric evaluation revealed deeper crypts in the small intestine of dogs with intestinal lymphangiectasia. Although plasma cells of all classes were diminished in the cranial parts of the small intestine, there was an absolute and relative increase of immunoglobulin G-containing plasma cells in the caudal small intestine in dogs with intestinal lymphangiectasia.

Animals↗