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Biomedical subjects

A Scholz

Publications and source records attributed to A Scholz.

At least 19 recordsLinked to original sources
PubMed2003

[The fight against venereal diseases in different political systems].

The fight against venereal diseases (VD) has often been influenced by the prevailing political and social conditions. At the end of 19th century the increase of VD demanded new strategies. In 1902 the German Society for the Control of VD was founded in Berlin. It was then followed by the foundation of the International Society against VD in Brussels in 1899. In the German empire and during the Nazi regime, authoritarian structures dominated the strategies against VD. The individual had to submit the interests of the society. Sociopolitical aspects influenced the discussions in the fight against VD during the Weimar republic. In 1927 the new laws to control VD met liberal demands.

Communicable Disease Control↗
PubMed2003

The emigration of Germany's Jewish dermatologists in the period of National Socialism.

In the context of our investigation, we found information on 432 (76%) of the 569 Jewish dermatologists in Germany. There is evidence that 57 (10%) of the Jewish dermatologists were murdered in concentration camps, 61 (10.7%) died a natural death, 13 (2%) committed suicide, and 25 (4%) survived the Third Reich in Germany. After 1933, 276 (49%) Jewish dermatologists were able to leave Germany; the United States of America was the main destination and 107 (or 41%) emigrated there. A total of 34 (13%) Jewish dermatologists emigrated from Germany to Palestine and 16 to Latin America. Regarding emigration to other European countries, 20 of the Jewish dermatologists from Germany went to Great Britain (including Walter Freudenthal, 1893-1952, and Ernst Sklarz, 1894-1975), and 24 emigrated to other European countries, such as France (Rudolf Mayer, 1895-1962), Sweden (Carl Lennhoff, 1883-1963), and the Netherlands (Otto Schlein, 1895-1944).

Dermatology↗
PubMed2002

Prospective two year follow up study comparing novel and conventional imaging procedures in patients with arthritic finger joints.

OBJECTIVE: To carry out a prospective two year follow up study comparing conventional radiography, three-phase bone scintigraphy, ultrasonography (US), and three dimensional (3D) magnetic resonance imaging (MRI) with precontrast and dynamic postcontrast examination in detecting early arthritis. The aim of the follow up study was to monitor the course of erosions during treatment with disease modifying antirheumatic drugs by different modalities and to determine whether the radiographically occult changes like erosive bone lesions of the finger joints detected by MRI and US in the initial study would show up on conventional radiographs two years later. Additionally, to study the course of soft tissue lesions depicted in the initial study in comparison with the clinical findings. METHODS: The metacarpophalangeal, proximal interphalangeal, and distal interphalangeal joints (14 joints) of the clinically more severely affected hand (soft tissue swelling and joint tenderness) as determined in the initial study of 49 patients with various forms of arthritis were examined twice. The patients had initially been divided into two groups. The follow up group I included 28 subjects (392 joints) without radiographic signs of destructive arthritis (Larsen grades 0-1) of the investigated hand and wrist, and group II (control group) included 21 patients (294 joints) with radiographs showing erosions (Larsen grade 2) of the investigated hand or wrist, or both, at the initial examination. RESULTS: (1) Radiography at the two year follow up detected only two erosions (two patients) in group I and 10 (nine patients) additional erosions in group II. Initial MRI had already detected both erosions in group I and seven (seven patients) of the 10 erosions in group II. Initial US had depicted one erosion in group I and four of the 10 erosions in group II. (2) In contrast with conventional radiography, 3D MRI and US demonstrated an increase in erosions in comparison with the initial investigation. (3) The abnormal findings detected by scintigraphy were decreased at the two year follow up. (4) Both groups showed a marked clinical improvement of synovitis and tenosynovitis, as also shown by MRI and US. (5) There was a striking discrepancy between the decrease in the soft tissue lesions as demonstrated by clinical findings, MRI, and US, and the significant increase in erosive bone lesions, which were primarily evident at MRI and US. CONCLUSIONS: Despite clinical improvement and a regression of inflammatory soft tissue lesions, erosive bone lesions were increased at the two year follow up, which were more pronounced with 3D MRI and less pronounced with US. The results of our study suggest that owing to the inadequate depiction of erosions and soft tissue lesions, conventional radiography alone has limitations in the intermediate term follow up of treatment. US has a high sensitivity for depicting inflammatory soft tissue lesions, but dynamic 3D MRI is more sensitive in differentiating minute erosions.

Adult↗
PubMed2001

Dynamic (19)F-MRI of pulmonary ventilation using sulfur hexafluoride (SF(6)) gas.

A new method for dynamic imaging of pulmonary wash-in and wash-out kinetics of inhaled sulfur hexafluoride (SF(6)) gas was developed. Measurements at the fluorine-19 Larmor frequency were performed in pigs using a gradient echo pulse sequence with 0.5 ms echo time and a measurement time of 9.1 s per image. Dynamic MRI was performed during wash-in and wash-out of SF(6) gas in mechanically ventilated porcine lungs. A postprocessing strategy was developed for quantitative determination of wash-out time constants in the presence of noise. Mean wash-out constants were 4.78 +/- 0.48 breaths vs. 4.33 +/- 0.76 breaths for left and right lung when ventilation was performed with low tidal volume, and 1.73 +/- 0.16 breaths vs. 1.85 +/- 0.11 breaths with high tidal volume ventilation. In conclusion, breath-hold MRI of SF(6) gas is feasible in large animals. Moreover, regional wash-in and wash-out kinetics of SF(6) can be determined noninvasively with this new method. Potential human applications are discussed. Magn Reson Med 45:605-613, 2001.

Animals↗
PubMed2001

[The graves of well-known dermatologists].

The location and condition of the graves of 48 famous dermatologists are identified. Brief personal data is presented for all the physicians. In seven instances, more detailed information about the dermatologists and their tombstones is provided to illustrate the value of graves as culture sites worthy of both honor and preservation.

Dermatology↗
PubMed2001

Ethanol reduces excitability in a subgroup of primary sensory neurons by activation of BK(Ca) channels.

Ethanol effects on the central nervous system have been well investigated and described in recent years; modulations, by ethanol, of several ligand-gated and voltage-gated ion channels have been found. In this paper, we describe a shortening of action potential duration (APD) by ethanol in approximately equal to 40% of small diameter neurons in rat dorsal root ganglia (DRG). In these neurons, designated as group A neurons, we observed an ethanol-induced increase in whole-cell outward-current. As iberiotoxin, a specific blocker of large-conductance calcium-activated K+ channels (BK(Ca) channels), blocks the effects of ethanol, we investigated the interaction between these channels and ethanol in outside-out patches. Open probability of BK(Ca) channels was increased 2-6 x depending on the concentration (40-80 mM approximately equal to 2-4 per thousand v/v) of ethanol. Functional consequences were a prolongation of the refractory period, which was reversible after addition of iberiotoxin, and reduced firing frequency during ethanol application. In contrast, another type of neuron (group B) showed a prolonged APD during application of ethanol which was irreversible in most cases. In 90% of cases, neurons of group A showed a positive staining for isolectin B4 (I-B4), a marker for nociceptive neurons. We suggest that the activation of BK(Ca) channels induced by clinically relevant concentrations of ethanol, the resulting modulations of APD and refractory period of DRG neurons, might contribute to clinically well-known ethanol-induced analgesia and paresthesia.

Action Potentials↗
PubMed2001

Temporal dynamics of lung aeration determined by dynamic CT in a porcine model of ARDS.

We used dynamic CT to identify two different time constants of lung aeration and their individual contribution to the total increase in cross-sectional lung area in healthy and experimentally damaged lungs. In five healthy pigs, inflation and deflation between 0 and 50 cm H2O was imposed during dynamic (250 ms/image) CT acquisition, and repeated after experimental lung injury by saline lavage. The fractional areas of density ranges, which represent aerated lung parenchyma, were determined planimetrically, and their time for expansion during the manoeuvre was fitted using a bi-exponential model. Thus, two compartments, their sizes, i.e. their relative contributions to lung area aerated by the manoeuvre, and their specific time constants (tau) were sought. Healthy lungs were characterized best by a one-compartmental behaviour with one tau only, both during inflation (median tau=0.5 s; range 0.4-0.6 s) and deflation (1.2 s; 1.1-1.3 s). In damaged lungs two compartments were found both during inspiration and expiration, with 86% (78-87%) of the recruitable lung area following a short tau of 0.5 s (0.5-0.6), and 14% (13-22%) following a longer tau of 9.1 s (8-16.8 s) during inflation. During expiration, damaged lungs had a short tau of 0.8 s (0.5-1.0 s) for 94% (84-100%) of deflated lung area, and a longer tau of 26.5 s (7.1-34.3 s) for 6% (0-16%). We conclude that dynamic CT indicates the relative size and temporal behaviour of functional compartments in normal and abnormal lungs. Our findings suggest that after lung damage, cyclic ventilation with inspiratory periods of <10 s duration will not achieve maximum recruitment for a chosen inspiratory pressure. In ARDS, the short expiratory tau predisposes to atelectasis formation if expiratory times are >1 s.

Animals↗
PubMed2000

[19F-MRT of pulmonary ventilation in the breath-hold technic using SF6 gas].

OBJECTIVE: Development of a method to analyze lung ventilation by 19F-magnetic resonance imaging (MRI) of inspired SF6 gas during breath hold. MATERIAL AND METHODS: Measurements were performed with a Siemens Magnetom Vision 1.5 T scanner using the conventional gradient overdrive. Coronal images of the lung were acquired using ultrafast gradient-echo pulse sequences with TR/TE/alpha = 1.4 ms/0.48 ms/40 degrees without slice selection. With NEX = 200 averages and MA = 32 x 64 raw data matrix, the acquisition time was 9 s/image. Higher spatial resolution of 4.7 x 6.3 x 15 mm3 was obtained with a three-dimensional pulse sequence (TR/TE/alpha = 1.6 ms/0.48 ms/65 degrees, NEX = 20) running for 49 s. Measurements wer performed in three anesthetized and ventilated pigs (18 kg). RESULTS: A nearly linear relation between SF6 concentration and 19F signal intensity was observed. The signal-to-noise ratio in images obtained without slice selection was 30.9, with slice selection it was 14.9. No differences between SF6 distribution to both lungs were observed in the animals. CONCLUSION: Breath-hold MRI of SF6 gas distribution in the lung was demonstrated for the first time. The low spin-density was compensated for by highly repetitive signal averaging. Breath-hold 19F-MR imaging of ventilated airspaces to assess SF6 distribution in the human lung appears to be an interesting new method, which can be implemented with little technical efforts, and does not rely on radioactive isotopes.

Animals↗
PubMed1999

Human axons contain at least five types of voltage-dependent potassium channel.

1. We investigated voltage-gated potassium channels in human peripheral myelinated axons; apart from the I, S and F channels already described in amphibian and rat axons, we identified at least two other channel types. 2. The I channel activated between -70 and -40 mV, and inactivated very slowly (time constant 13.1 s at -40 mV). It had two gating modes: the dominant ('noisy') mode had a conductance of 30 pS (inward current, symmetrical 155 mM K+) and a deactivation time constant (tau) of 25 ms (-80 mV); it accounted for most ( approximately 50-75 %) of the macroscopic K+ current in large patches. The secondary ('flickery') gating mode had a conductance of 22 pS, and showed bi-exponential deactivation (tau = 16 and 102 ms -80 11 mV); it contributed part of the slow macroscopic K+ current. 3. The I channel current was blocked by 1 microM alpha-dendrotoxin (DTX); we also observed two other DTX-sensitive K+ channel types (40 pS and 25 pS). The S and F channels were not blocked by 1 microM DTX. 4. The conductance of the S channel was 7-10 pS, and it activated at slightly more negative potentials than the I channel; its deactivation was slow (tau = 41.7 ms at -100 mV). It contributed a second component of the slow macroscopic K+ current. 5. The F channel had a conductance of 50 pS; it activated at potentials between -40 and +40 V, deactivated very rapidly (tau = 1.4 ms at -100 mV), and inactivated rapidly (tau = 62 ms at +80 mV). It accounted for the fast-deactivating macroscopic K+ current and partly for fast K+ current inactivation. 6. We conclude that human and rat axonal K+ channels are closely similar, but that the correspondence between K+ channel types and the macroscopic currents usually attributed to them is only partial. At least five channel types exist, and their characteristics overlap to a considerable extent.

Adolescent↗
PubMed1999

Hormone-dependent recruitment of NF-Y to the uteroglobin gene enhancer associated with chromatin remodeling in rabbit endometrial epithelium.

Expression of the rabbit uteroglobin gene is hormonally induced in cells of the endometrial epithelium during the preimplantation phase of pregnancy. Here we show that progesterone activation of the gene is mediated by two clusters of hormone responsive elements located between 2.4 and 2.7 kilobase pairs upstream of the transcriptional start site. Between these two clusters, genomic footprinting studies in the intact endometrial epithelium reveal the hormone-inducible occupancy of several cis-acting elements. One of the protected elements shows sequence homology to the consensus binding site of the transcription factor NF-Y, which binds to the element in gel shift experiments. This uteroglobin Y box is essential for enhancer activity in transient transfection experiments with endometrial and non-endometrial cell lines, in accordance with the ubiquitous expression of NF-Y. To understand why binding of this ubiquitous factor to the uteroglobin Y box in endometrium depends on hormone induction, we examined the chromatin structure of the relevant gene region. In the uninduced state, the enhancer region appears to be organized into positioned nucleosomes. Upon hormone induction, this nucleosomal pattern is lost and the enhancer region becomes hypersensitive to nucleases, suggesting that a hormone-induced change in the local chromatin structure unmasks previously unaccessible binding sites for transcription factors. Our results emphasize the limitations of using transient transfection assays for the functional analysis of cis-acting elements and underline the need for including the native chromatin organization in this kind of studies.

Animals↗
PubMed1999

[Therapy of deep leg vein thrombosis. When is surgical therapy indicated?].

In spite of quite a few clinical trials the benefit of venous thrombectomy is seen controversially. The primary objectives of treating venous thrombosis are survival rate, prevention of pulmonary embolism and of postthrombotic syndrome. We report our experience with 47 patients who underwent venous thrombectomy. The mortality rate was 0%. We did not observe clinically relevant pulmonary embolism. After two years 90% of thrombectomised veins were patent. The mortality rates given in the literature of conservative treatment with heparin and following oral anticoagulation are 0.4 to 1.6%. Fibrinolysis shows mortality rates of 1 to 2.4, and thrombectomy of 3.8%, respectively. Venous thrombectomy is an effective treatment to prevent pulmonary embolism. In our own experience we saw no clinically significant pulmonary event. The danger of embolism rises with the proximity of the venous thrombus. Therefore those patients may have the greatest potential benefit from thrombectomy who present with a mobile inguinal thrombus or a thrombus in the iliac vein. So far there are no statistically sufficient data to support the indication of thrombectomy to prevent a postthrombotic syndrome.

Adult↗
PubMed1998

Properties and functions of calcium-activated K+ channels in small neurones of rat dorsal root ganglion studied in a thin slice preparation.

1. Properties, kinetics and functions of large conductance calcium-activated K+ channels (BKCa) were investigated by the patch-clamp technique in small neurones (Adelta- and C-type) of a dorsal root ganglion (DRG) thin slice preparation without enzymatic treatment. 2. Unitary conductance of BKCa channels measured in symmetrical high K+ solutions (155 mM) was 200 pS for inward currents, and chord conductance in control solution was 72 pS. Potentials of half-maximum activation (V ) of the channels were linearly shifted by 43 mV per log10 [Ca2+]i unit (pCa) in the range of -28 mV (pCa 4) to +100 mV (pCa 7). Open probabilities increased e-times per 15-32 mV depolarization of potential. 3. In mean open probability, fast changes with time were mainly observed at pCa > 6 and at potentials > +20 mV, without obvious changes in the experimental conditions. 4. BKCa channels were half-maximally blocked by 0.4 mM TEA, measured by apparent amplitude reductions. They were completely blocked by 100 nM charybdotoxin and 50 nM iberiotoxin by reduction of open probability. 5. Two subtypes of small DRG neurones could be distinguished by the presence (type I) or absence (type II) of BKCa channels. In addition, less than 10 % of small neurones showed fast (approximately 135 V s-1) and short ( approximately 0.8 ms) action potentials (AP). 6. The main functions of BKCa channels were found to be shortening of AP duration, increasing of the speed of repolarization and contribution to the fast after-hyperpolarization. As a consequence, BKCa channels may reduce the amount of calcium entering a neurone during an AP. 7. BKCa channel currents suppressed a subsequent AP and prolonged the refractory period, which might lead to a reduced repetitive activity. We suggest that the BKCa current is a possible mechanism of the reported conduction failure during repetitive stimulation in DRG neurones.

Algorithms↗
PubMed1998

[The scientific development in dermatology in Germany in relation to the emigration of Jewish dermatologists during national socialism].

The anti-semitic laws let to the persecution of the Jews in Germany during the time of National Socialism. About 600 Jewish dermatologists had to suffer from the prohibition of their profession. 63% of them left Germany. The emigrants mainly preferred to move out to the U.S. The policy of coordination and elimination of the National Socialists led to the reappointment of dermatological chairs in universities. The National Socialists also forced the change in the boards of dermatological societies and the change of the editorial boards of dermatological journals. All papers of the three leading dermatological journals were analysed for the evaluation of the development of science. The assessment included the number of articles, the origin of the authors and the contents of articles (research, clinics, diagnostic, therapy). From 1933 to 1945 the number of papers per year decreased consequently, especially during the Second World War. During the whole time the number of German authors increased and the number of abroad living authors decreased. There was a very good and interesting international exchange of information in the journal "Archiv für Dermatologie und Syphilis". The activity reduced clearly after the beginning of the Second World War in 1939. The analysis of contents resulted in a reduction of basis science research and an orientation to the clinical research. Papers about therapeutical possibilities were always published. The emigration of Jewish dermatologists led to a continuous reduction of scientific activities and to an extensive international isolation.

Dermatology↗
PubMed1998

Hormone-induced recruitment of Sp1 mediates estrogen activation of the rabbit uteroglobin gene in endometrial epithelium.

Steroid hormones activate gene expression by interaction of their receptors with hormone-responsive DNA elements and tissue-specific or ubiquitous factors. To monitor the molecular changes on the promoter of the rabbit uteroglobin gene during early pseudopregnancy in vivo, we have applied the genomic footprinting methodology to endometrial tissue. Estrogen induction results in the simultaneous occupancy of an estrogen-responsive element and an adjacent GC/GT box in the promoter. DNA binding assays demonstrate that the corresponding regulatory factors are the ligand-induced estrogen receptor and the ubiquitous transcription factor Sp1. Both factors functionally synergize in primary endometrial cells, showing that the GC/GT box is an essential part of a composite estrogen-responsive unit. However, the estrogen receptor and Sp1 do not bind cooperatively to their sites in vitro, suggesting that other mechanisms might be responsible for the hormone-dependent binding of Sp1 in vivo. Since hormone treatment leads to the appearance of a distinct DNase I-hypersensitive site over the promoter chromatin, an estrogen-induced change in the local chromatin structure could facilitate binding of Sp1 in vivo.

Animals↗