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Biomedical subjects

G Schulze

Publications and source records attributed to G Schulze.

At least 37 records · Page 2Linked to original sources
PubMed1997

Age-related muscle stiffness: predominance of non-reflex factors.

This study was aimed at assessing the contribution of reflex and non-reflex factors to the muscle tone of old female Wistar rats. The hind foot of a rat was flexed or extended at the ankle joint by 25 degrees over 250 ms. The resistance of the foot to passive movements (torque, mechanomyogram), as well as the reflex electromyographic activity in the gastrocnemius and tibialis anterior muscles, were recorded simultaneously. Moreover, the impact of the blockade of the reflex activity caused by the local anesthetic lignocaine (1-2 ml of a 2% solution, injected in the vicinity of the sciatic nerve) on the muscle tone was investigated. Additionally, old rats' hind leg muscle samples were analysed using fluorescent microscopy for the expression of fibronectin, which is an early marker of connective tissue formation. It has been shown that old rats are characterized by (i) a substantially increased resistance of flexor muscle stiffness (measured during extension) and unchanged resistance of extensors (measured during flexion), (ii) the loss of a major part of the reflex electromyographic activity and (iii) the increased content of fibronectin in muscles. Moreover, it has been shown that lignocaine, which completely blocked the electromyographic reflex activity in the gastrocnemius and tibialis anterior muscles in young animals, was unable to counteract the resistance of these muscles to passive movements in old rats. The present results suggest that the muscle stiffness seen in old rats is not due to a reflex response, but depends mainly on non-reflex factors--chiefly on a large overgrowth of non-elastic connective tissue replacing degenerated active muscle fibers.

Aging↗
PubMed1996

Impaired plasticity of neurons in aging. Biochemical, biophysical, and behavioral studies.

Age-related correlation of impaired plasticity of neurons (biochemical and biophysical aspects) and behavioral alterations were investigated in young (3.5 months) and extremely aged (approximately 40 months) female Wistar rats. Age-dependent significant differences in second messenger (cAMP and Ins (1,4,5)P3) concentration and signal transduction via muscarinic and dopaminergic receptors were found. The results point to the specifically impaired coupling between dopamine D1 receptor and GS protein, which underlies normal brain aging. However, cholinergic neurotransmission may be modulated at another level in extremely aged rats. Thus, it appears that the site of affection in coupling of receptor and G protein and/or G protein-dependent signal transduction in aging cannot be generalized. This indicates that alterations in the coupling of signal transduction depend on diverse neurotransmitter receptors with advanced age. The age-dependent alterations in the cAMP and PI signal pathways could be due to changes in the physical properties of the membranes. To support this hypothesis, age-dependent changes in the physical state and the biochemical composition of synaptosomal membranes from the cortex, cerebellum, and striatum were examined by measuring the steady-state fluorescence amisotropy of the membrane probes 1,6-diphenyl-1,3,5-hexatriene (DPH), trimethylammonium-DPH (TMA-DPH), and trimethylammoniumpropyl-DPH (TMAP-DPH). Significant differences in the physical properties of the synaptosomal membranes existed between young and very aged rats, expressed by a higher anisotropy in the 40-month-old rat brain tissue. The changes in the physical properties of the membranes were in line with the determined age-dependent alterations in the chemical composition, e.g., the increase in cholesterol content of the aged membranes.

Age Factors↗
PubMed1996

The influence of dizocilpine (MK-801) on the reserpine-enhanced electromyographic stretch reflex in rats.

The electromyographic (EMG) stretch reflex in the gastrocnemius and tibialis anterior muscles was elicited by passive bending and stretching of the rat's hind foot in the ankle joint. The EMG stretch reflex was increased by pretreatment with reserpine (10 mg/kg ip) which is a model compound commonly used to induce parkinsonian rigidity in laboratory animals. Dizocilpine (MK-801) (0.32, 0.64 and 1.28 mg/kg sc) inhibited long-latency supraspinal components of the reserpine-increased EMG stretch reflex, whereas a short-latency spinal component was not diminished. The present results suggest that MK-801 exhibits an antiparkinsonian action against reserpine-induced rigidity.

Animals↗
PubMed1996

Influence of 6-hydroxydopamine lesion of the dopaminergic nigrostriatal pathway on the muscle tone and electromyographic activity measured during passive movements.

The aim of the present study was to find out whether a 6-hydroxydopamine-induced lesion of the substantia nigra in rats would evoke muscular rigidity of the parkinsonian type. Simultaneous measurements of muscle resistance (mechanomyogram) of the hind foot to passive flexion and extension at the ankle joint, as well as of the electromyographic activity of the antagonistic muscles of the ankle joint--the gastrocnemius and tibialis anterior--in rats were carried out one, two and four weeks after bilateral injections of 6-hydroxydopamine (6.5 micrograms/microliter) into the substantia nigra. After immunohistochemical staining of brain sections for tyrosine hydroxylase, the rats were divided into two groups in which, on average, either 70% (63-80%) or 89% (81-96%) of nigral cells degenerated. Larger lesions increased the resistance (mechanomyogram) of the rat's hind leg to passive movements two weeks after 6-hydroxydopamine injection, whereas smaller lesions did not. Muscle rigidity was accompanied by an increase in the movement-induced reflex electromyographic activity in both muscles, mainly in long-latency components which are most probably influenced by supraspinal mechanisms. However, in spite of relatively large lesions of nigral dopamine cells, already four weeks after the lesion, muscle rigidity and the respective electromyographic activity diminished dramatically, which seems to result from very effective compensatory mechanisms operating in young lesioned rats. The results suggest that the muscle rigidity induced by the 6-hydroxydopamine nigral lesion seems to be a good model of parkinsonian rigidity.

Animals↗
PubMed1996

Pelviscopic Survey in Eastern Germany

In 1994 a survey conducted in eastern Germany reported 27,595 pelviscopies from 101 clinics and 3307 hysteroscopies from 53 clinics. Clinics reported 129 serious complications by pelviscopy that required laparotomy or second-look laparoscopy. The complication rate was 4.6/1000 procedures. One death occurred during pelviscopy and none during hysteroscopy. The trend to perform endoscopy was 71.7% for pelviscopy and 80.5% for hysteroscopy, which is continuously increasing.

Journal Article↗
PubMed1996

The role of reflex activity in the regulation of muscle tone in rats.

The aim of the study was to assess the contribution of reflex activity to the regulation of muscle tone in rats. The experiment was carried out on young Wistar male and female rats. The hindfoot of a rat was flexed or extended at the ankle joint by 25 deg over 250 ms. The resistance of the foot to passive movements, as well as the electromyographic (EMG) activity in the gastrocnemius and the tibialis anterior muscles, were recorded simultaneously. During passive movements, reflex EMG activity developed simultaneously in both antagonistic muscles of the foot. Three components were distinguished: a short-latency EMG-A (within the first 0-20 ms of a movement), long-latency EMG-B (within 60-160 ms), and EMG-C (within 220-340 ms). When the amplitudes of EMG-B and EMG-C components of the gastrocnemius muscle reflex response were greater than 50 microV, a significant correlation was found between them and the maximum resistance of the hindfoot (MMGmax) during flexion, whereas no such correlation was observed for the tibialis anterior muscle. No correlation was found when the amplitudes of the log-latency components of the gastrocnemius muscle were less than 50 microV. Moreover, no correlation was observed between the EMG-A and the MMG(max). The above results suggest that: (1) the muscle tone of the gastrocnemius muscle in rats seems to be regulated by long-latency (supraspinal) reflexes only when the level of EMG activity exceeds a critical threshold of ca 50 microV; (2) when the level of EMG activity is lower, a major role in the resistance of hindlimb muscles is played by some non-neuronal factors; and (3) the proposed animal model emphasizes new aspects of the reflex which may be useful in a search for basic mechanisms underlying changes in the muscle tone.

Animals↗
PubMed1995

Interleukin 5 expressing allergen-specific T-lymphocytes in patients with house dust mite sensitization: analysis at a clonal level.

Interleukin 5 (IL-5) is a T-cell lymphokine known to stimulate development, functional activity, and in vitro survival of eosinophils. Tissue and blood eosinophilia occurring during allergic responses of the immune system are potentially mediated by IL-5 secreting T-cells. To test this hypothesis a series of allergen-specific T-cell clones were established from peripheral blood and skin lymphocytes of patients with atopic dermatitis and house dust mite sensitization. In addition, alloreactive T-cell clones were also prepared from peripheral blood lymphocytes of healthy donors. Cloned T-cells were analyzed for IL-5 mRNA expression and IL-5 secretion by means of in vitro gene amplification using the reverse transcriptase polymerase chain reaction and IL-5 specific oligonucleotide hybridization, as well as IL-5-specific ELISA. A majority of allergen-specific long-term cultured T-cell clones (84%) of different donors and of either phenotype (CD8+ or CD4+) disclosed IL-5 transcripts on stimulation with lectins. Almost all clones exhibiting IL-5 transcripts also released immunoreactive IL-5 protein into their culture supernatants. In contrast, only 2% of alloreactive T-cell clones obtained from healthy donors and none of alloreactive T-cell clones of one atopic patient investigated expressed detectable amounts of IL-5 mRNA in response to lectin stimulation, all of whom were CD4+. These results suggest that eosinophilia observed in allergic responses in the peripheral blood and in tissues at the site of induced late-phase cutaneous reaction may be associated with IL-5 release by allergen-specific T-cells.

Animals↗
PubMed1995

Ion exchange micro columns for on-line preconcentration of heavy metalsII. On-line break-through test for zinc, cadmium and lead.

An on-line break-through test for zinc, cadmium and lead has been carried out by means of a flow-through cell and computerized potentiometric stripping analysis. This test has been applied to seventeen ion-exchange materials and enabled within a short time a predecision about the suitability of a resin for a special preconcentration problem. For the determination of the three trace elements in drinking water five ion exchangers are found to be appropriate without restriction and eight resins with some restrictions (not suitable for all three elements, weak matrix influences).

Journal Article↗
PubMed1994

Evaluation of physical dependence liability of l-deprenyl (selegiline) in animals.

l-Deprenyl is a useful drug that has been successful in the clinical treatment of parkinsonism. However, l-deprenyl is a phenylalkylamine derivative that undergoes metabolic transformation to l-methamphetamine and l-amphetamine. Therefore, the question arises whether l-deprenyl possesses amphetamine-like abuse liability. This article reviews a series of different preclinical studies in rats that used experimental procedures to provide preclinical information predictive of human abuse liability. In one series we investigated whether repeated administration of l-deprenyl to rats resulted in observable signs of physical dependence. In a second series of studies, the effects of l-deprenyl on the cortical electrical activity of freely moving rats were investigated. Finally, the influence of l-deprenyl on behavior of the animals was studied. In all studies, different stereospecific configurations of amphetamine and deprenyl were compared. During and after 6 weeks of oral administration of l-deprenyl, no signs of physical dependence were observed in rats after withdrawal of the drug. In contrast, with d-deprenyl, d-amphetamine, and racemic d,l-amphetamine, signs indicative of physical dependence were observed after withdrawal of the drug. For example, the body weight of the rats was increased. In addition, changes in electroencephalograms and behavior of rats induced by l-deprenyl and l-amphetamine were different from those produced by the d-enantiomers. Thus preclinical results confirm the clinical experience that therapeutically relevant doses of l-deprenyl are without physical dependence liability.

Amphetamine↗
PubMed1993

[Lactones. 24. "Gamma-lactonized" neuroleptics--synthesis, stereochemistry and affinity at the D2 receptor].

Addition of piperidines 15a-d to methylene lactones 8,14a gives the "gamma-lactonized" diphenylbutylpiperidine-type neuroleptics 3a,b,d,4a-d. 8 can be produced by cyclization or--as well as 14--from the corresponding alpha-carboxylactone. 1H- and 13C-nmr data give evidence for the equatorial position of the aminomethyl group in all derivatives of 3 and 4 and bisequatorial-trans-configuration in 4a-d. 3H-spiroperidole displacement at the D2 receptor in rat brain by 3,4 and the "gamma-lactonized" butyrophenone neuroleptics 1,2a-c was investigated. Some compounds show moderate up to high (3b) activity.

Animals↗
PubMed1993

Characterization of Yersinia pseudotuberculosis serogroups O9, O10 and O11; subdivision of O1 serogroup into O1a, O1b, and O1c subgroups.

In this study, three new antigens (O9, O10 and O11) of Yersinia pseudotuberculosis are described. The O1 antigen is further subdivided into O1a, O1b and O1c. The methods used to prepare specific antisera for O-antigen identification are also described. Furthermore, the H antigens of these new serogroups are determined and their biochemical characteristics analysed. The antigenic formulae of the known serogroups within the basic antigenic scheme introduced by the authors' laboratories are presented.

Antigenic Variation↗
PubMed1992

Muscle stiffness and continuous electromyographic activity in old rats; an animal model for spasticity?

A mechanomyographic response of the hind foot to passive straightening and bending, as well as an electromyographic activity of the gastrocnemius and tibialis anterior muscles were recorded in old (35-44-month-old) and young female rats. In old rats, spontaneous, tonic electromyographic activity patterns were concurrently observed in both antagonistic muscles; they were low-amplitude, dense tonic activity and continuous, high-amplitude, sparse electromyographic activity. The tonic electromyographic activity was correlated with a decline in the strength and mass of muscles, as well as with motor disturbances, including paresis of the rigidly straightened backward hind legs, dragged behind by an animal. In muscles of old rats, morphological features of a chronic denervation atrophy were found. Baclofen (10 and 15 mg/kg, i.p.) diminished the spontaneous tonic electromyographic activity and potently decreased the whole body muscle tone, whereas Madopar (50 mg/kg of L-DOPA+12.5 mg/kg of benerazide) was ineffective. It is suggested that old rats in which the above-described pathologic alterations are observed might be a useful animal model in the search for basic etiopathological mechanisms of spasticity and similar disturbances found in humans.

Aging↗
PubMed1991

Incorporation of phosphonic acid diesters into lipid model membranes. Part II. X-ray and neutron diffraction studies.

Mixtures of egg phosphatidylcholine and phosphonic acid diethyl or dibutyl esters of the general type RP(O)(OR')2 with R = hexane or dodecane were studied at room temperature in the fluid lamellar state by X-ray and by neutron diffraction. Generally a molar ratio of lipid and ester of 1:0.5 was used. Additionally an equimolar lipid/ester mixture of hexane phosphonic acid diethyl ester was studied. Depending on the ester used and its concentration a single L alpha-phase was observed above a certain water content which changes to an L alpha + water two phase system at high water concentration. Despite the large amounts of the amphiphilic ester molecules incorporated in the membrane and their high molecular asymmetry, the mixtures qualitatively show the typical hydration and swelling behaviour of non-charged lipid membranes. However, the incorporation of the esters induces a higher hydration capacity, a lateral extension and a decrease in membrane thickness. The position of the ester molecules and their orientation in the membrane were determined by neutron diffraction using partially deuterated esters. The esters were found to be located with their phosphonic moiety near or in the lipid/water interface. The lamellar structure contradicts this location of the cone-shaped ester molecules which should increase the tendency to form hexagonal structures. However, the experimental findings can be understood if one considers a partial interdigitation of the last hydrocarbon groups of the lipid chains accompanied by a larger disorder in the hydrophobic centre of the membrane. In the case of hexane phosphonic acid dibutyl ester, a vertical translocation of the ester takes place below a certain water content where it is distributed between two locations at the lipid water interface and the centre of the membrane.

Esters↗
PubMed1990

Effect of enantiomers of deprenyl (selegiline) and amphetamine on physical abuse liability and cortical electrical activity in rats.

In the present study, whether the repeated administration of (-)deprenyl to rats resulted in physical dependency was investigated. In a second experiment, the effect of (-)-deprenyl was investigated on the cortical electrical activity of freely moving rats and last, the influence of (-)-deprenyl on the behaviour of the animals was studied. In all experiments, different stereospecific configurations of amphetamine and deprenyl were also employed in order to establish differences and similarities. During and after the chronic oral administration of (-)-deprenyl (4 mg/kg) over 6 weeks, no signs of physical dependency were observed in rats after withdrawal of the drug. By contrast, (+)-deprenyl (5 mg/kg, p.o.) and (+)-amphetamine (5 mg/kg, p.o.) induced typical symptoms of amphetamine-dependency: during withdrawal of drug, the body weight of the rats was increased. A similar phenomenon was observed after oral administration of (+/-)-amphetamine (6 mg/kg, p.o.). After a single oral administration of (-)-deprenyl (1 and 5 mg/kg) and (-)-amphetamine (10 mg/kg, p.o.), decreases in delta and increases in theta frequency bands in the EEG were observed. In contrast, (+)-amphetamine (1 mg/kg, p.o.), (+/-)-amphetamine (5 mg/kg, p.o.) and (+)-deprenyl (1 and 5 mg/kg, p.o.) evoked increases in the mean power values in delta and decreases in theta frequency bands. In agreement with the EEG studies, the (-) and (+)-isomers of amphetamine and deprenyl caused differences in the behaviour of the animals. Based on these findings, it can be concluded that (-)-deprenyl undergoes a stereospecific metabolism in the organism and the amounts of its metabolites with (+) configuration might be negligible, even at the larger doses which are necessary to inhibit monoamine oxidase-B (MAOB) in brain.

Amphetamine↗
PubMed1990

Learning abilities of rats in multiple T-mazes of two degrees of complexity under the influence of d-amphetamine.

The effect of d-amphetamine on the learning capacity of male Wistar rats was investigated in multiple T-mazes in two experiments of increasing or decreasing degree of difficulty. Running speed, distance covered and the number of errors were scored to indicate proficiency and success of learning. These parameters, as well as the distribution of errors (goal-directed orientation), correction of errors (situational orientation) and latency at the decision points (discrimination time) were considered to represent cognitive components. The results demonstrated an experiment effect in that the rats showed more difficulty in learning, as exhibited by a slower running speed and more errors, in the maze with successively increasing demands than in the one with decreasing demands. Oral self-administered d-amphetamine in a dosage of 3-4 mg/kg/day or 7-8 mg/kg/day significantly increased the running speed in a dose-dependent manner. By contrast, success of learning and goal-directed orientation decreased. Situational orientation was, however, dose-dependently improved, at least in the experiment with the increasing demand.

Animals↗
PubMed1990

[Reactions of different Enterobacteriaceae and Vibrionaceae species in BRILA-MUG (Fluorocult) bouillion].

In order to test the usefulness of BRILA-MUG (= Fluorocult) medium (Merck) for isolation and identification of total coliforms and faecal coliforms in surface water according to the EC guidelines for bathing waters a total of 969 strains of different Enterobacteriaceae and Vibrionaceae species was examined under different culture conditions. These included 486 E. coli (reference strains of O-groups 1-170, enterotoxin and Verotoxin-producing strains), 149 Salmonella (subspecies I-VI), 92 Yersinia, 44 Shigella, 64 Vibrio, 16 Aeromonas, and 118 strains of other Enterobacteriaceae species. After 48 h incubation at 36 degrees C 372 (82.0%) of 486 E. coli showed the typical reactions of gas formation, fluorescence (beta-glucuronidase activity), and indole production. Examination of fluorescence after addition of 1 N NaOH (0.5 ml), or testing of indole production after subculture in tryptophane containing broth improved the amount of typical reactions to 434 (95.4%). Incubation at 44 degrees C for 48 h gave less favourable results as compared with that at 36 degrees C. Out of 483 strains of other species 3.9% Salmonella strains of subspecies II-IV, 6.25% Citrobacter freundii, and 50% Edwardsiella tarda strains yielded reactions typical of E. coli. Shigella and Yersinia strains occasionally produced indole or fluorescence, but never visible gas.

Culture Media↗