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Biomedical subjects

H Schumann

Publications and source records attributed to H Schumann.

At least 19 recordsLinked to original sources
PubMed1995

[Predictive factors of minimally effective nCPAP ventilation in treatment of obstructive sleep apnea?].

BACKGROUND: Nasally applied continuous positive airways pressure (nCPAP) ventilation is an effective treatment of obstructive sleep apnoea syndrome (OSAS). As the lowest effective nCPAP-level (nCPAPmin) inter-individually is quite variable individual pressure titration under polysomnographic monitoring is necessary. AIM: To determine whether nCPAPmin can reliably be predicted on the basis of clinical and polysomnographic variables. PATIENTS AND METHODS: A set of 77 unselected OSAS-patients was investigated in the sleep laboratory. We used a standard sleep-related questionnaire, examined anthropometric variables, performed lung function tests and blood gas analyses, and measured nasal cross-sectional area as well as nasal flow resistance. In the night prior to the nCPAP titration a cardiorespiratory polygraphy was performed. Stepwise multiple regression analysis using the titrated nCPAPmin as dependent variable and the clinical and polygraphic data as independent variables revealed gender (GES), neck circumference (NCF), body mass index (BMI), and apnoea-/hypopnea index (AHI) as the optimal set of predictors of nCPAPmin in this model. RESULTS: Multiple regression analysis with these factors yielded the following equation: predicted nCPAPmin = 1.95 + 0.80 x GES + 0.09 x BMI + 0.01 x NCF + 0.03 x AHI (woman: GES = 1; man: GES = 2). The reliability of the equation was tested with a second set of 180 prospective OSAS-patients. In these patients the mean nCPAP-level as titrated in the sleep laboratory was 9.1 +/- 2.0 mbar, whereas the mean predicted nCPAP-level was 8.4 +/- 3.6 mbar (p = n.s.). In 51% of the patients the difference between nCPAPmin measured and predicted was greater than +/- 1 mbar. CONCLUSION: This equation is neither sufficient to reliably predict nCPAPmin nor to prescribe nCPAP without individual pressure titration. The calculated nCPAP-level might however contribute to choosing the most suitable flow generator prior to the titration night.

Adult↗
PubMed1990

[The occurrence of Diptera in living quarters].

More than 150 species of Diptera belonging to 46 families were caught in a flat in the outskirts of Berlin between April and October 1986. 2148 specimens were collected. Fannia canicularis was the most frequent species with 726 specimens. Drosophila melanogaster, Culex pipiens, Lucilia sericata, Sarcophaga carnaria, Calliphora vicina, Muscina stabulans and Fannia manicata were other important synanthropic flies, which inclusively Fannia canicularis amounted 55% of the total catching rate. The remaining species of Diptera have only an insignificant medical importance, because of the random occurrence in flats or of their small size. A brief assessment of the sanitary important species is given.

Animals↗
PubMed1988

Antitumor properties of organometallic metallocene complexes of tin and germanium.

The antitumor activity of the four metallocene compounds decaphenylstannocene [eta 5-(C6H5)5C5]2Sn(II), decabenzylstannocene [eta 5-(C6H5CH2)5C5]2Sn(II), decaphenylgermanocene [eta 5-(C6H5)5C5]2Ge(II), and decabenzylgermanocene [eta 5-(C6H5CH2)5C5]2Ge(II), containing the main group IV elements tin or germanium as the central metal atom and two pentasubstituted cyclopentadienyl ring ligands in sandwich arrangement, were tested against Ehrlich ascites tumor in female CF1 mice. The complexes caused cure rates of 40% to 90% of the animals treated over rather broad dose ranges. With both germanocene complexes, no strong dose-activity relationship was manifest. The toxicity of all four metallocenes was low, the LD10 values of both stannocenes being 460 and 500 mg/kg, and those of both germanocenes higher than 700 mg/kg. Regarding the isolated pentasubstituted cyclopentadiene ligands (C6H5)5C5H and (C6H5CH2)5C5H, these also exhibited antitumor activity which was less pronounced than that of the metal-containing sandwich complexes. Decasubstituted stannocene and germanocene compounds represent a new type of non-platinum group metal antitumor agents structurally differing from known inorganic and organometallic cytostatics.

Animals↗
PubMed1988

[Botfly larva skin infestation in a donkey].

In January 1987 7 larvae of Hypoderma diana were found in a donkey. The infection probably took place on a horse pasture in Fürstenwalde, Frankfurt (O.) region, grazed also by roes, the main hosts of H. diana.

Animals↗
PubMed1986

Investigation into the functional characteristic of m. quadriceps femoris in man with "stimulation mechanography".

The force and positive slope under isometric conditions produced by electrically evoked contractions of the m. quadriceps femoris in man were measured during two days without physical work and on two days with different kind of exercise. The relationship between force and slope is described by a logarithmic function. The changes after exercise were different in dependence of the kind of exercise.

Biophysical Phenomena↗
PubMed1983

Compensation of the low-pass filter properties of the current measuring internode in potential-clamped myelinated nerve fibres.

The bandwidth of membrane current measurements in potential-clamped Ranvier nodes is limited by the low-pass filter properties of the internodes. If about 35% of the current measuring internode is grounded via an additional electrode, the bandwidth of this internode increases by a factor of about 40. Consequently, in potential clamp experiments the measured time course of the early ionic currents changes markedly, while the duration of the capacity current is shortened.

Animals↗
PubMed1982

Changes in myelinated nerve fibres caused by insulating layers.

Single myelinated nerve fibres of the frog were investigated electron microscopically and electrophysiologically. The following results were obtained. Dissected internodes exhibited small deteriorations only compared to undissected fibres. In the vaseline seal the cross section area of the axoplasm was reduced by a factor of about 3. In the air gap the corresponding figure was about 5. With electrical measurements of up to 2 h the vaseline seal did not affect the axoplasmic resistance of the belonging internode. In corresponding experiments with an air gap, the axoplasmic resistance of the internode doubled after 49 +/- 14 min (mean +/- S.D.; n = 8). Thereafter, the resistance increased rapidly up to about 3,000 times normal, depending on the atmospheric humidity. The consequences of these findings for potential clamp experiments are discussed.

Animals↗
PubMed1981

A method for increasing the frequency response of voltage clamped myelinated nerve fibres.

In voltage clamp experiments on myelinated nerve fibres the time resolution of the current measurement is limited by the low-pass characteristics of the internodes. We increased the corner frequency of the current passing internode by grounding one half of this internode externally. Using a simplified equivalent circuit we calculated an increase in the bandwidth of the internode by a factor of about 6. Consequently, the peak value of the recorded capacity current increased while its duration was considerably shortened.

Animals↗