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Biomedical subjects

M Seidel

Publications and source records attributed to M Seidel.

At least 19 recordsLinked to original sources
PubMed1992

[The segmental organization and horny structure of the claw of the dog].

This study classifies the segments of the dog claw and presents a new conception to define crown and wall segments that deviates from the common statements in literature. The perioplic segment extends along the internal surface of the claw fold (vallum). The crown segment lies in the unguicular groove, and there in a semicircular zone. In the crown segment there is development of horn tubuli, but these lose their tubular structure before they have reached the top of the claw. The wall segment, adjacent distally, comprises a dorsal ridge, and lateral surfaces proximally and distally which are all marked by superficial lamellar-shaped surface configurations. The sole segment shows desquamative soft horn and is situated between the free margin of the wall segment palmar/plantar to the unguicular process. The new conception of homology of dog claw distinguishes between main and secondary criteria. The main criterion is the epidermal and dermal configuration. Secondary criteria are the typical horn products (for example perioplic horn) and dimension, shape and topography of segments. The sterile/fertile-bed theory, which was believed to be the determining factor for the classification of the dog claw, is neither the proper method to define the individual segments nor to judge the rate of cornification.

Animals↗
PubMed1991

Anthralin derivatives--inhibition of 5-lipoxygenase--antipsoriatic efficacy.

Inhibition of 5-lipoxygenase by anthralin (1) and 41 derivatives is determined: the acids 38 and 39, the lactones 40-42 and 9-anthrone (8) are the most potent inhibitors, the lactone 41 reaching the efficacy of nordihydroguaiaretic acid (NDGA). The results were correlated with the hydrophilic/lipophilic balance of the test compounds and their clinical efficacy as far as known. There is no correlation between the "minimum structure" of Krebs and Schaltegger concerning antipsoriatic activity and the inhibitory effects against 5-lipoxygenase.

Animals↗
PubMed1991

Structure-function relationship of new anthralin derivatives assayed for growth inhibition and cytotoxicity in human keratinocyte cultures.

HaCaT keratinocyte cultures were exposed to twelve hydrophilic anthralin derivatives 1 to 12 with substituents at C-1 and C-8 of the anthrone skeleton, of one H at C-10 and of both H's at C-10 by lacton rings. After 3 microM treatment growth was determined by cellular protein content, 3H-thymidine- and 14C-amino-acid-uptake and cytotoxicity by the release of cytoplasmic LDH into the culture medium. In comparison to acetone control (100%) anthralin suppressed mean protein content, as well as DNA- and protein-synthesis to 33, 28, and 21%, respectively, and the drug revealed an enzyme release of 660%. In relation to the parent drug we found similar cell growth inhibitory effects of compounds 4, 6, 8, 9, 10, and 12. Deriv. 4, 8, and 10 were, however, to some extent less cytotoxic than anthralin, whereas deriv. 6, 9, and 12 were in the same range. An extreme suppression of growth parameters which differed from the anthralin effect by a factor 0.5-0.8 was caused by deriv. 11, showing the same cytotoxicity. Deriv. 1, 2, 3, 5, and 7 did not demonstrate any cytotoxicity. Concerning growth parameters, deriv. 2 induced a slight stimulation, deriv. 3 and 7 were completely ineffective, deriv. 1 and 5 induced slightly to moderately inhibited proliferation but both being much less effective than anthralin. These data indicate that the "minimum structure" concept by Krebs and Schaltegger--claiming 1-hydroxy-9-anthrone as a precondition for clinical antipsoriatic potency--is not valid at least in cell-biological tests and point toward possible usefulness of some experimental model compounds as alternative antipsoriatics.

Anthralin↗
PubMed1991

Dithranol, glucose-6-phosphate dehydrogenase inhibition and active oxygen species.

Inhibition of glucose-6-phosphate dehydrogenase (G6-PDH) by dithranol (anthralin, CAS 480-22-8) has been studied in the presence of catalase, superoxide dismutase (SOD) and various scavengers of active oxygen species. Most scavengers were found to be either inhibitors of G6-PDH by themselves or simply without effect. The combined addition of catalase and SOD as well as the heat-denatured enzymes and the oxygen radical scavengers alpha-tocopherol and salicylic acid markedly reduced the inhibitory effect of dithranol. The direct exposure of G6-PDH to active oxygen species led to different results. When liberated from a water-soluble naphthalene endoperoxide, singlet oxygen was without effect whereas photosensitization with methylene blue resulted in a total loss of enzyme activity. Experiments under anaerobic conditions revealed that this inhibition was accomplished by the triplet state of the sensitizer. Superoxide anion radical was highly effective at concentrations corresponding to the amount of that produced by a 10 mumol/l dithranol solution. In contrast, hydroxyl, alkylperoxyl and alkoxyl radicals were all less efficient. H2O2 and alkylhydroperoxides did not alter the enzyme activity. The results suggest that .O2- is the potent species towards G6-PDH, if dithranol acts through formation of active oxygen species.

Anaerobiosis↗
PubMed1990

Stroke volume and left ventricular output in preterm infants with patent ductus arteriosus.

To assess the effect of patent ductus arteriosus (PDA) on left ventricular output (LVO) we studied stroke volume (SV), LVO, and heart rate (HR) in 21 very low birth wt preterm neonates with clinically symptomatic PDA before and after surgical ligation. Six additional infants were also studied before PDA with left-to-right shunt was detectable by the pulsed Doppler technique. Gestational age (median and range) was 28 (24-32) wk. SV was measured by duplex Doppler and M-mode echocardiography, and LVO was calculated as product of SV and HR. LVO was 419 (305-562) mL/min/kg during symptomatic PDA. It decreased to 246 (191-292) mL/min/kg after ligation (n = 21, p less than 0.001). SV was 2.69 (1.98-4.10) mL/kg during symptomatic PDA decreasing to 1.63 (1.22-1.98) mL/kg after ductal closure (n = 21, p less than 0.001). HR did not change after ductal closure. In the six infants with three examinations, LVO and SV were normal before detectable ductal left-to-right shunt and after ligation, but LVO was increased by 59.5 +/- 23% (mean +/- SD) (p less than 0.05), and SV by 60 +/- 32% (p less than 0.05) during symptomatic PDA. In conclusion, preterm neonates with RDS, requiring mechanical ventilation, increased LVO during symptomatic PDA by increasing their SV, and not by changing their HR.

Cardiac Output↗
PubMed1989

Use of physiological substrates for zymograms of disaccharidases after separation in immobilized pH gradients.

A new technique is described for in situ visualization of the activity of intestinal disaccharidases after isoelectric focusing in immobilized pH gradients using their physiological substrates. The reaction principle is based on the oxidation of D-glucose, liberated by the disaccharidases, into D-gluconolactone and the production of NADH by glucose dehydrogenase. At the sites of enzymatic activity, tetrazolium salts present in the reaction mixture are reduced to relatively water-insoluble formazans by NADH. The rate of formazan production is increased by the presence of phenazine methosulfate. An additional modification of the technique involves the use of polyvinyl alcohol in the substrate solution. Due to the increase in the viscosity of the substrate solution, leakage of the enzyme from the IPG gels is minimized. Incubation times can thus be prolonged without loss of resolution and band-blurring.

Disaccharidases↗
PubMed1989

[Phenomenology and therapy of neuroleptic-induced akathisia--a review of the literature].

The neuroleptic-induced akathisia (NIA) often appears as a side effect of neuroleptic therapy in psychotic individuals. It can accompany or outlive the period of neuroleptic treatment. Besides the objective symptoms of motor restlessness it is especially the subjective symptoms and complaints as inner restlessness, anxiety, and depression, which cause severe annoyance or even torment patients. Exacerbations of disease symptoms treated with neuroleptics can occur. After outlining development of the concept of akathisia and of the knowledge of NIA some relevant findings in the field of NIA, especially in respect to their clinical pictures and their connections to related neuroleptic-induced side effects, are discussed. Development and present stand of treatment of NIA are described. Treatment with betablockers plays a central role. Pathophysiological aspects are touched in context with therapeutical considerations. The current state of knowledge of NIA allows a better understanding of pathophysiology in neuroleptic side effects in general, enables an almost sufficient treatment of NIA with betablockers, demonstrates the necessity of responsible and cautious use of neuroleptics by physicians and the necessity of careful guidance of such patients who are treated with neuroleptics.

Akathisia, Drug-Induced↗
PubMed1988

CNS neuronal cell line-derived factors regulate gliogenesis in neonatal rat brain cultures.

Recent studies suggest that heterotypic cell-cell interactions influence gliogenesis in the developing rat central nervous system. CNS neuron-derived factors have been hypothesized to exist, and several have been identified and partially characterized which affect the number of oligodendrocytes in vitro. In order to study further the role of neurons in gliogenesis, we have used serum-free culture conditions, the B104 CNS neuronal cell line as a source of soluble factors, and dissociated neonatal rat brain cells as a source of glial cells. We have analyzed the response of the glial cells to serum-free B104 conditioned medium using morphological, immunocytochemical, autoradiographic, and enzymatic methods. Dose-dependent increases in the number of morphologically identified oligodendrocytes occur in response to this conditioned medium. Galactocerebroside (GalC) is a specific marker for oligodendrocytes, and the A2B5 antigen marks bipotential glial progenitor cells and their progeny: immature oligodendrocytes and type 2 astrocytes. In the presence of conditioned medium, the number of cells expressing GalC and/or A2B5 antigen increases over time when measured at 4, 8, and 12 days in vitro. A significantly weaker effect is seen if serum is also present. Since the vast majority of A2B5-positive cells in conditioned medium treated cultures lack glial fibrillary acidic protein (GFA), indicative of type 2 astrocytes, they represent glial progenitors and immature oligodendrocytes. Double immunostaining combined with autoradiography suggests that the latter cell types are the target cells for the oligodendrocyte-promoting activity. In addition, the conditioned medium markedly increases 2',3' cyclic nucleotide 3'-phosphodiesterase (an oligodendrocyte marker) and to a lesser extent enhances glutamine synthetase activity (an astrocyte marker). Type 1 astrocytes are also more morphologically differentiated in this condition, and their percentage is decreased simultaneously. Conditioned medium from other donor neural cells either has no activity or is much less effective than B104 conditioned medium. The active factors are soluble, sensitive to both trypsin and 100 degrees C treatment for 20 min, and appear to be 30-100 kilodaltons by stirred cell ultrafiltration. In summary, we have identified a potent source of growth-stimulating factors that produce increased numbers of glial progenitor cells and oligodendrocytes; the same conditioned medium also appears to inhibit type 1 astrocyte proliferation.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1988

A comparative study of G-induced neck injury in pilots of the F/A-18, A-7, and A-4.

The introduction of the high performance F/A-18 into the Navy and Marine Corps units has brought attention to the problem of high +Gx-induced neck pain and injury. Aviators from the Light Attack Wing, Pacific were surveyed and the results were categorized by aircraft type. We found that 74% of F/A-18 aviators surveyed reported neck pain with high +Gz. Out of 37 pilots reporting neck injury, 11 required removal from flight status averaging 3 days. The inability to function effectively during high G flight and the impact of lost pilot days highlight the need for further study into prevalence and solutions for high +Gz-induced neck injury.

Adult↗
PubMed1987

[Benzodiazepines and barbiturates in chronic alcoholics and opiate addicts. An epidemiological study of hospitalized addicts].

In a prospective study of 282 chronic alcoholics and 67 opiate addicts, frequency and pattern of drug intake were determined by questioning and urinalysis on admission to a special unit of a psychiatric hospital. 20.2% of alcoholics and 44.8% of opiate addicts stated that they had taken psychotropic drugs before admission, women in both groups naming such drugs significantly more frequently than men. But taking into account results of urinalysis, 25.5% of alcoholics and 31.3% of opiate addicts were found to have taken benzodiazepines before hospital admission. 41.8% of opiate addicts either stated or were found to have taken barbiturates. High dosages of benzodiazepines were found in those alcoholics who had mentioned taking them. Thus in practice the treatment of addicts differs markedly from recommendations made by well-known experts. There is also a need to improve the clinical diagnosis and treatment of addicts.

Adult↗
PubMed1987

[Psychiatry and psychotherapy in the many-sided contributions of Alexander Mette].

Appreciating the personality and work of Alexander Mette, who founded together with Karl Bonhoeffer this journal, especially his psychiatric and psychotherapeutic inclinations as well as his influences on the development of our discipline are taken into consideration in the frame of his many-sided activities as a man of letters and cultural policy.

Germany↗