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Biomedical subjects

M Reuter

Publications and source records attributed to M Reuter.

At least 145 records · Page 8Linked to original sources
PubMed1995

The flatworm nervous system: pattern and phylogeny.

The flatworms occupy a position at the base of the metazoan phylogenetic tree; they have a bilateral symmetric nervous system and an archaic brain. The following aspects, brought into focus by the use of new methods, will be dealt with in the present paper. 1. The high degree of diversity on all levels of the flatworm nervous system (NS). 2. The concept of main nerve cords is defined and the use of this concept in avoiding confusions in the terminology of nerve cords is stressed. 3. The archaic nature of the stomatogastric NS is reviewed. 4. The new data about neuronal celltypes implying advanced features at this low phylogenetic level. 5. The ultrastructural studies of neuronal cells indicating (A) that a common secretory cell type containing dense-core vesicles is archaic and a likely progenitor cell type for conventional neurons of advanced flatworms and (B) that an independent evolution of synaptic structures and glial cells has occurred inside the flatworm taxon. 6. The multitude of neuroactive substances demonstrated by light microscopic histofluorescence, immunocytochemistry, liquid chromatography, and HPLC. The cholinergic, aminergic, and peptidergic substances often occur in different neuronal compartments.

Amino Acid Sequence↗
PubMed1995

Serotonin, reserpine, and motility in Mesocestoides tetrathyridia. An experimental spectrofluorometry and immunocytochemistry study.

The relationship between serotonin (5-HT) and motility in tetrathyridia of Mesocestoides vogae (syn. M. corti) was studied with the aid of reserpine. Reserpine decreases the content of 5-HT as measured spectrofluorometrically and immunocytochemically and, furthermore, inhibits the motility, thus indicating a connection between the two. The results support the hypothesis about 5-HT being an excitatory neurotransmitter of motor activity in M. vogue. New neuroanatomical details were revealed by immunocytochemical staining.

Animals↗
PubMed1995

The nervous system of Tricladida. I. Neuroanatomy of Procerodes littoralis (Maricola, Procerodidae): an immunocytochemical study.

The organization of the nervous system of Procerodes littoralis (Tricladida, Maricola, Procerodidae) was studied by immunocytochemistry, using antibodies to authentic flatworm neuropeptide F (NPF) (Moniezia expansa). Compared to earlier investigations of the neuroanatomy of tricladid flatworms, the pattern of NPF immunoreactivity in Procerodes littoralis reveals differences in the following respects: 1. Shape and structure of the brain. 2. Number and composition of longitudinal nerve cords. 3. Shape of branches of, and transverse connections between, main ventral nerve cords. 4. Composition of the pharyngeal nervous system. The rich innervation by NPF immunoreactive (IR) fibres and cells of the subepithelial muscle layer, the pharynx musculature and the musculature of the male copulatory apparatus indicates a neurotransmitter or neuromodulatory influence on muscular activity.

Animals↗
PubMed1995

The nervous system of Tricladida. II. Neuroanatomy of Dugesia tigrina (Paludicola, Dugesiidae): an immunocytochemical study.

The nervous system (NS) of Dugesia tigrina has been studied by immunocytochemical double-staining, using the authentic flatworm neuropeptide, neuropeptide F (NPF), and serotonin (5-HT) on cryosections. This technique provides a precise morphological (descriptive) account of the NS. The results show that the central nervous system is shaped like a horseshoe. The brain is composed of two lateral lobes connected by three commissures, one antero-dorsal in front of the cerebral eyes and two, more ventral, behind the eyes. The pair of main nerve cords extend from the lateral lobes of the brain to the tail end of the worm. Cross sections reveal a very close contact between lateral branches from the main cords and the submuscular plexus. Thin cord-like lateral nerves are formed by longitudinal plexal fibres. No dorsal cords were observed. The patterns of immunoreactivity to NPF and 5-HT differ from each other in several respects. In the walls of gut diverticula only NPF immunoreactive (IR) cells and fibres were observed. Only NPF-immunoreactive cells occur in the parenchyma along dorso-ventral nerve fibres connecting the dorsal and ventral parts of the submuscular plexus. The number of 5-HT-immunoreactive cells associated with the main nerve cords (MCs) is greater than that of the NPF-immunoreactive cells, and the spongy structure of the MCs is more apparent following immunostaining for 5-HT. Thin 5-HT-immunoreactive fibres were observed in the subepithelial plexus, penetrating the basal lamina and innervating a rhabdite-free ventro-lateral sensory area along the body periphery. The correspondence between MCs in the lower flatworms (Catenulida and Macrostomida) and the Seriata (Tricladida and Proseriata) confirms the status of the MCs in flatworms as the most important and stable neuronal characteristic, and constitutes support for the hypothesized common origin of the MCs in flatworms.

Animals↗
PubMed1995

Neuropeptides and serotonin in the cestode, Proteocephalus exiguus: an immunocytochemical study.

Neuropeptides and serotonin in the cestode, Proteocephalus exiguus: an immunocytochemical study. International Journal for Parasitology 25: 673-682. Neuropeptide F (NPF), RFamide and serotonin (5-HT) immunoreactivities have been detected in the nervous system of P. exiguus procercoids and adults, using an indirect immunocytochemical technique in conjunction with confocal scanning laser microscopy. The peptidergic nervous system of the procercoid is well developed, with two brain ganglia, three pairs of longitudinal nerve cords, transverse ring commissures and nerves in the suckers, all showing NPF-immunostaining. Strong NPF- and RF-immunostaining was observed in the CNS and PNS of the adult worm. The distribution patterns of the two neuropeptides were similar. Immunoreactivity for 5-HT was found only in the CNS.

Animals↗
PubMed1995

[Quantitative computed tomography of the lung in the early diagnosis of asbestosis: initial results in asbestos-exposed navy personnel].

AIM: To evaluate the diagnostic role of respiratory gated quantitative CT of the lung with regard to the early detection of asbestos-induced lung fibrosis. MATERIAL AND METHODS: 29 navy personnel with a mean asbestos exposure of 21.3 years and exclusively low profusion stages with regard to plain film X-ray (0/1 and 1/0, ILO 1980) were examined using high resolution CT and respiratory gated quantitative CT of the lung. RESULTS: A low but significant increase of the global lung density with -816 HU (range -844 to -749 HU) was found in comparison with the age-matched reference values of -829.8 HU (range -834 to -819 HU). In individual cases the histogram analysis demonstrated a shift of the density distribution towards higher density intervals without corresponding findings in HRCT. No alterations in lung function were observed. There was no correlation between the latency period or length of exposure and density values. CONCLUSION: The respiratory gated quantitative CT of the lung may potentially develop into an accessory parameter for monitoring dust exposed personnel.

Adult↗
PubMed1995

[Kinematic MRI in degenerative cervical spine changes].

AIM: To evaluate functional stenosis of the cervical spine, kinematic MRI was performed in 23 healthy volunteers and 23 patients with degenerative disease. MATERIAL AND METHOD: Kinematic MRI of the cervical spine was done from 50 degrees of inclination to 30 degrees of reclination. Depending on the maximum inclination and reclination the range of motion was divided into 9 equal angle positions. At each angle position sagittal T2* weighted gradient echo sequences were performed. RESULTS: In relation to the neutral position a physiological narrowing of the ventral epidural space was seen in healthy volunteers at inclination (50 degrees) in up to 50% and respectively widening at reclination (30 degrees) in up to 10%. An increase of spinal canal stenosis or even spinal cord compression was seen at inclination in 5 patients (22%) and in 15 patients (65%) at reclination. No change of spinal canal stenosis was found in three patients (13%). CONCLUSION: In patients with degenerative disease of the cervical spine kinematic MRI demonstrated in some patients functional spinal canal stenosis with myelon compression which was not seen in standard MRI. Therefore kinematic MR imaging can be recommended as a complementary examination in the early detection of functional myelon compression and in planning the further therapeutic work-up.

Adult↗
PubMed1995

In vivo P-31-MR-spectroscopy of focal hepatic lesions. Effectiveness of tumor detection in clinical practice and experimental studies of surface coil characteristics and localization technique.

RATIONALE AND OBJECTIVES: The influence of partial tumor sampling in a volume of interest (VOI) on the ratios of phosphorus metabolites was examined by localized phosphorus magnetic resonance spectroscopy (P-31-MRS). Experiments were performed to investigate the characteristics of the surface coil used and precession of spatial localization. METHODS: A total of 24 patients with liver metastases and 20 volunteers were studied by P-31-MRS. Patients were divided in two groups: VOI < 50% (n = 8) and VOI > 50% (n = 16) occupied by tumor. For evaluation of the surface coil and localization method (image selected in vivo spectroscopy), phantom studies were performed. RESULTS: Superficial focal liver tumors were detectable with a surface coil at a distance within the coil radius. The image selected in vivo spectroscopy permitted the study of phosphorus metabolism in a defined VOI, phosphomonoester/beta-adenosine triphosphate and phosphodiester/beta-adenosine triphosphate were elevated significantly in spectra of both patient groups. CONCLUSIONS: Detection of small tumor volumes within a VOI filled by less than 50% of the tumor is possible, with results statistically different from that in normal volunteers.

Adult↗
PubMed1995

Application of the maximum entropy method for evaluating phosphorus-31-magnetic resonance spectra in patients with liver metastases.

RATIONALE AND OBJECTIVES: The clinical feasibility and application of the maximum entropy method for data analysis from in vivo phosphorus-31-magnetic resonance (P-31-MR) spectra of the liver were determined. METHODS: Image-guided localized P-31-MR spectroscopy was performed in 24 patients with liver metastases and in 20 healthy volunteers. The spectra were obtained with a whole body scanner operating at 1.5 T using a surface coil. Phosphomonoester/beta-adenosine triphosphate (ATP), phosphodiester/beta-ATP, and inorganic phosphate/beta-ATP were calculated from the maximum entropy method-spectra and from spectra evaluated with standard data processing (Fourier transformation spectra). RESULTS: Phosphomonoester/beta-ATP and phosphodiester/beta-ATP were increased significantly with both methods in patients' spectra. Maximum entropy method spectra showed a distinct pattern with low noise. It was easier to determine peak borders and to attach resonances to the different metabolites using this method. CONCLUSIONS: Maximum entropy method is an alternative method for evaluation and quantification of P-31-MR spectra data and is preferred to standard data processing with Fourier transformation in cases of reduced signal-to-noise ratio of spectra.

Aged↗
PubMed1995

The significance of distance and orientation of restriction endonuclease recognition sites in viral DNA genomes.

Studies on phage T3 and T7 have shown that these viruses avoid restriction not only by the phage-coded Ocr (and S-adenosylmethionine hydrolase) protein functions or by the complete loss of specific recognition sites for certain restriction endonucleases from their genomes, but also that there are two additional modes: resistance towards EcoP15 (which recognizes a non-symmetrical sequence) is achieved by an identical orientation of all the recognition sites in the virus genome (strand bias) and in the case of EcoRII by the extreme reduction in number and thereby greater distance between recognition sites in the genome. These observations led to the discovery that certain restriction endonucleases require the simultaneous cooperation with two DNA sites for their function, as well as to the ongoing elucidation of the molecular modes of action of these enzymes. Type II and type III enzymes display fundamentally different mechanisms of protein-DNA interaction. For EcoRII we favor a model of simultaneous binding of two DNA sites to a dimeric enzyme molecule (neighbouring sites of the same, looping, DNA molecule or sites located on different DNA molecules), while the action of EcoP15 seems to conform with a tracking-collision model of two enzyme molecules bound to inversely oriented recognition sites. In addition to podoviruses T3 and T7, strand bias of recognition sequences for different type III DNA modification-restriction enzymes is also observed in the inoviruses M13, IKE and PF3.

Bacteriophage T3↗
PubMed1995

[CT angiographic imaging of atypical arterial blood supply to the liver by the superior mesenteric artery].

Variations of the celiac trunk are seen in 25-35% of all patients. In 10-12% the right hepatitic artery arises from the superior mesenteric artery, the left hepatic artery in 4-5%. An aberrant origin of the common hepatic artery is seen in about 2.5%. We report about a patient with liver cell adenoma, in whom we diagnosed preoperatively the atypical origin of the common hepatic artery by performing CT angiography in the MIP technique (MIP = Maximum Intensity Projection). Conventional angiography as well as intraoperative findings confirmed the diagnosis.

Adenoma, Liver Cell↗
PubMed1994

Differential regulation of stem cell factor mRNA expression in human endothelial cells by bacterial pathogens: an in vitro model of inflammation.

Production of hematopoietic growth factors by endothelial cells plays a pivotal role during inflammatory processes. Stem cell factor (SCF) is known to be expressed constitutively in endothelial cells. To investigate the regulation of this cytokine expression by inflammatory stimuli, we cocultured human umbilical vein endothelial cells (HUVEC) with various gram-negative bacterial strains (Escherichia coli, Yersinia enterocolitica, Chlamydia trachomatis, and Neisseria meningitidis, respectively). Experiments were performed with bacterial concentrations ranging from 10(2) to 10(7) bacteria/mL for 3 hours. SCF-specific mRNA expression was studied using Northern blot analysis. Stimulation with the enteropathogenic bacterial strains Y enterocolitica and E coli resulted in a significant concentration-dependent increase of SCF mRNA expression. Similar results were obtained in coculture experiments with N meningitidis. As shown in experiments with E coli, the accumulation of SCF transcripts was also time-dependent. In contrast, coculture of HUVEC with the intracellular gram-negative strain C trachomatis had no effect on SCF mRNA expression. To elucidate the role of the gram-negative bacterial cell wall components, we stimulated HUVEC with bacterial lipopolysaccharide (LPS). LPS induced a maximal SCF mRNA accumulation within 2 hours followed by decrease of SCF-specific transcripts to the basal level after 24 hours. In addition, we exposed HUVEC to the classical inflammatory cytokine interleukin-1 alpha (IL-1 alpha). Kinetic experiments showed a similar pattern of regulation with an increase of SCF mRNA within 2 hours, persisting up to 12 hours, and a decrease to basal transcription after 24 hours. From these data, we conclude that SCF expression is regulated by inflammatory stimuli, such as IL-1 alpha and bacterial pathogens, suggesting an important role of SCF during inflammation.

Cells, Cultured↗
PubMed1994

[High-resolution CT (HRCT) of the lung in Wegener's granulomatosis].

HRCT of the lung and plain chest X-ray were performed to reveal pulmonary manifestation in primary diagnostics or reevaluation of 35 patients with Wegener's granulomatosis. Pleural and parenchymal pathology was detected in chest X-ray of 20 (57%) and in HRCT of 30 (85.7%) patients. Granulomas with and without cavitations and with smooth or spiculated margins were deemed pathognomonic. Nonspecific findings were infiltrates, thickened interlobular septae and fibrotic changes of parenchyma and pleura. Ground glass opacities, traction bronchiectasis and small cysts were only visible on HRCT. As expected HRCT proved to be more sensitive in detecting subtle lung alterations than plain film chest X-ray. It helps to differentiate acute inflammatory and thus potentially curable processes from chronic fibrotic changes in Wegener's granulomatosis.

Adult↗
PubMed1994

[Magnetic resonance tomography and computerized tomography of Wegener's granulomatosis of the orbits].

Of a total of 121 patients with histological proven Wegener's Granulomatosis, orbital involvement occurred in 12 cases. Eight of them underwent magnetic resonance imaging (MRI) of the head and brain, in 2 cases computed tomography (CT) was additionally performed. With MRI orbital granulomas had a low signal intensity in T1- and T2-weighted spin-echo sequences. After i.v. contrast medium administration an inhomogeneous enhancement was found. Because of the multiple imaging planes and high soft tissue contrast, orbital granulomas were better delineate with regard to the intraorbital muscles and the optic nerve using MRI than with CT. Osseous destruction and sclerosis of the orbital walls were demonstrated more effectively using CT. MRI and CT are thus complementary for diagnosing and staging, of orbital granulomas and periorbital involvement in Wegener's Granulomatosis.

Adult↗
PubMed1993

Use of specific oligonucleotide duplexes to stimulate cleavage of refractory DNA sites by restriction endonucleases.

There are numerous restriction endonucleases (ENases) which are known never to achieve total cleavage of certain unmethylated target DNAs. In addition to EcoRII we found seven ENases (AtuBI, Cfr9I, Eco57I, Ksp632I, NaeI, NarI, and SauBMKI) that were stimulated by oligodeoxyribonucleotide (oligo) duplexes containing enzyme-specific recognition sequences to cut the target DNAs much more efficiently and in most cases even to completion. These enzymes are class-II and class-IIS Enases isolated from different bacterial species and possess a varying number of specific sites in the refractory DNA substrates. For DNA analysis and large-scale preparation of certain restriction fragments where complete digestions are essential we recommend taking into account the fact that various ENases can be activated by specific oligo duplexes to drive restriction digestions to completion.

Base Sequence↗