Search PubMed⌕ Search

Biomedical subjects

R Schmidt

Publications and source records attributed to R Schmidt.

At least 631 records · Page 35Linked to original sources

[Effect of infrared radiation on the kinetics of the guinea pig's epidermis cells. Comparison with UV radiation effect].

In vivo exposition of guinea pig epidermal cells to infra-red irradiation (IR) led to significant, biphasic reduction of the proliferating activity after 6 h and 72 h. Not before 168 h after exposure, the proliferating activity rose above the normal rate. The quantitative alterations of DNA-proliferating cells went along with prolongation of the S-phase and the cell cycle. UV-irradiated cells react earlier by reduction of the DNA-proliferating activity directly followed by stages of hyperproliferation.

Animals↗

Phospholipids involved in specific binding of 12-O-(5-azido-2-nitrobenzoyl)phorbol-13-acetate to epidermal microsomes, a photolabeling study.

The preparation of 12-O-(5-azido-2-nitro)benzoylphorbol-13-acetate (NABPA) is described. It is used as a photoaffinity probe to study the biochemical components involved in the specific binding of phorbol esters to an epidermal particulate fraction (microsomes) from NMRI mice: without irradiation NABPA binds in a saturable and high affinity manner (KD = 12 nM; Rt = 2.6 pmol/mg protein) to microsomes; after irradiation (at 350 nm) specific photolabeling (representing specific binding of NABPA) is found of phospholipids (phosphatidyl-serine (PS) and -ethanolamine(PE)), but not of protein. The results are discussed in the context of protein kinase C being a receptor for phorbol esters.

Affinity Labels↗

[Meningopolyneuritis (Garin-Bujadoux, Bannwarth) erythema chronicum migrans disease of the nervous system transmitted by ticks].

The clinical spectrum of this remarkable non-syphilitic spirochaetosis (spirochaeta infection) of the nervous system is described in light of 53 further cases with reference to our earlier description of 47 cases. As the etiological diagnosis is not possible in all cases the knowledge of clinical courses is especially important. Males are affected almost twice as often as women. The disease is especially prevalent in the sixth decade. Usually, the syndrome begins in the warm season with exquisite pain and other sensory irritations in combination with marked malaise. Initial signs during the winter as well as painless clinical courses were also noted. About one half of the patients remembered contact with arthropodes or a chronic migrating erythema. In most cases (95%), asymmetrical peripheral signs followed the painful stage. More than two thirds of the patients showed affection of cranial nerves, usually facial palsy. Twenty percent demonstrated paresis of the extremities alone, the combination of involvement of cranial nerves and extremities was noted in one third of the cases. The sensory signs were usually only mild. Occasionally, the neurological impairment was limited to isolated sensory impairment. In contrast to the closely related Lyme disease, central nervous affection as well as cardiac and arthritic involvement is rare: 34 percent demonstrated mild psychopathological impairment; in one case a Babinski-phenomenon was elicited. Knee joint pain and gonarthritis were found in one case each. Even though meningeal signs were usually absent, the CSF showed alterations suggestive of chronic lymphocytic meningitis in all cases. At the same time, local synthesis of all three immune globulins was documented, especially of IgM (85%).

Adolescent↗

High-yield purification of plasma membranes from transformed human keratinocytes in culture.

The density pertubation technique with cationic silica microbeads was applied to prepare highly purified plasma membranes from cultured human keratinocytes. Trypsinized cells were coated successively with the beads (diameter approximately 50 nm, gravity greater than 2 g/cm3) and polyacrylic acid before they were lysed by osmotic shock and mechanical shear. The plasma membranes remained in the form of large open sheets which could easily be separated from other cell organelles and the cytosol by low-speed centrifugation. The membrane preparation was characterized by scanning and transmission electron microscopy, marker enzyme activities, one-dimensional sodium dodecyl sulfate polyacrylamide electrophoresis, and the specific beta-adrenergic receptor count. A yield of 79 +/- 9% was calculated by comparing the amount of beta-adrenoceptors in the purified membrane preparation with that of a crude cellular particulate fraction. The specific beta-adrenoceptor count of these two preparations was 1.2 +/- 0.02 and 0.2 +/- 0.05 pmol/mg protein, respectively, indicating a 6-fold improved purification with this microbead technique. The purified membranes were essentially free from contamination of other cell organelles.

Cell Line↗

Antirespiratory and antiproliferative activity of anthralin in cultured human keratinocytes.

The effect of anthralin and its oxidation products, anthralin-dimer and anthralin-quinone, on protein content and thymidine incorporation as well as CO2 production from glucose and glutamine has been studied in transformed human keratinocytes in vitro. Anthralin exhibited the strongest inhibition, the dimer was generally less active and the quinone inactive. Respiration and thymidine incorporation were the most sensitive cellular functions showing 50% inhibition at about 1 and 3 microM anthralin, respectively. Comparison of the inhibition kinetics of anthralin with those of antimycin A and mitomycin C showed that anthralin behaved as an inhibitor of mitochondrial function rather than of DNA replication. The biologic effects were triggered in the first minutes of exposure to the cells when anthralin became rapidly associated with the cell membranes. Labeling experiments with [14C]anthralin revealed that the manifestation of the biologic response occurring after a latency phase of some hours coincided with the accumulation of radioactivity in the intracellular particulate fraction. The cytosol remained essentially unlabeled.

Anthracenes↗

[Effect of Visotrast (R) and bilirubin on lipase and alpha-amylase activities of pancreatic secretions].

The contamination of pancreatic juice obtained by endoscopic retrograde catheterism of the papilla by cannulation of the pancreatic duct with contrast medium is possible. When the amount of "VisotrastR 370" is more then 0.05 ml per ml one observes a decrease of the lipase while alpha-amylase is unchanged.--Bilirubin has also an influence on the activity of lipase - but not on the alpha-amylase.

Bilirubin↗

Data reduction for electron isodose measurements.

Recent developments in computer technology enable the use of direct measured data without complex calculations for the isodose generation of electron fields of a 42 MeV Betatron. To reduce the time necessary for measuring the isodose data, different procedures to measure and generate electron matrices are investigated. Different methods to reduce the amount of data necessary for the isodose-generation are introduced. Under certain circumstances isodose data for numerous field sizes can be generated from a set of data of one field with sufficient accuracy.

Electromagnetic Fields↗

The responsibility for the study protocol in a drug trial.

A well-designed protocol is an essential part of any clinical trial. In a drug trial it should be the result of a joint effort involving the physician performing the trial at the clinic and the specialist in the drug company. The contribution of both the two partners varies depending on the stage of the development and the innovativeness of the compound. A clinical pharmacologist and a statistician should also be involved in drafting the protocol. The participation of the latter is mandatory for multicenter trials.

Clinical Trials as Topic↗

Clinical results after therapy with fast neutrons (DT, 14 MeV) since 1976 in Hamburg-Eppendorf.

In Hamburg since 1976 to 1980 we have treated 328 patients with fast neutron (DT, 14 MeV) and after reconstruction of the generator further 69 patients in 1984. The therapy with DT-neutrons had the best curative effect on high differentiated tumors. With the standard dose of 16 Gy in four weeks or--treating tumors in radiosensitive organs like brain and intestine--with a photon-neutron schedule, we have seen no necroses in normal tissues. The rate of medium or slight subcutaneous fibroses is not more than 10%. The local effect on tumors in our pilot study has been better than with megavoltage therapy in invasive thyroid cancer, prostate cancer stage C, soft tissue sarcoma and also in rectum-carcinoma. The best results have been achieved with neutrons only, but a photon-neutron schedule may be more effective as megavoltage therapy only. With our DT-neutrons we find some indications for better results than with megavoltage therapy if we use sophisticated treatment planning and if we strictly observe the tolerance dose of the different tissues and organs. The therapeutic index of our monoenergetic DT-neutrons is higher than with cyclotron-produced neutrons.

Aged↗

Evaluation of the silica microbead method for isolation of red beet protoplast plasma membrane sheets.

The silica microbead procedure was utilized for the isolation of plasma membrane sheets from protoplasts of a higher plant, the red beet (Beta vulgaris L.). Membrane yields, as determined by recovery of an exogenous membrane marker were approx. 75%. The plasma membrane fraction contained the enzyme marker, pH 6.5, vanadate-sensitive, K+-stimulated, Mg2+-ATPase and small amounts of mitochondria, endoplasmic reticulum, and possibly tonoplast. The silica microbead procedure was also used for the isolation of intact vacuoles from microbead-coated protoplasts.

Cell Fractionation↗