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H Reichelt

Publications and source records attributed to H Reichelt.

At least 19 recordsLinked to original sources
PubMed1993

Fast perfluorocarbon imaging using 19F U-FLARE.

The application of an ultra-fast low angle RARE technique for the 19F imaging of perfluorocarbons (PFCs) used as temporary blood substitutes is described. This sequence is attractive for fast 19F imaging studies that measure the biodistribution of PFCs in vivo, due to its high signal-to-noise ratio. Extensions of this technique for the chemical shift selective measurement of fluorine T1 values are presented. Using the linear dependence between the oxygen partial pressure (pO2) and the T1 relaxation rate of PFC resonances this technique makes possible the fast in vivo measurement of oxygen tension. Using the sequence in a diffusion sensitized form 19F measurements of the diffusion constants of PFCs are also presented. Phantom experiments to test the methods, and in vivo images obtained in rat studies are given and discussed.

Animals↗
PubMed1992

Blood substitutes made on the basis of perfluorocarbons inhibit intracellular energy generation.

Although perfluorocarbons (PFC) are chemically inert, toxic reactions are observed on using them as fluorocarbon emulsions in blood substitutes. Six to twelve hours after exchanging about half of the circulating blood of conscious rats pathobiochemical reactions occur despite a high interarterial oxygen pressure. They indicate the disturbance of intracellular energy generation, which is characterized by a decrease in ATP, increase in ADP, inorganic phosphate and potassium, increase in NADH and lactate. Impurities of perfluorocarbons and effects of the surfactant were excluded to be causes of this disturbance. The following hypotheses were proposed: Storing of perfluorocarbons in the mitochondrial membrane decreases the ATP-forming proton gradient on the membrane and the electron transport in cytochromes is disturbed, respectively.

Adenosine Triphosphate↗
PubMed1992

Interaction of beta-carboline with chick embryo spontaneous motility.

The effect of beta-carboline (beta-CCE) on spontaneous motility and its development was studied in chick embryos between the 11th and 19th day of incubation. 1. Acutely administered beta-CCE (7.5 mg/kg e.w.) already induced significant activation of motility in 11-day-old embryos. From the 17th day of incubation activation acquired a paroxysmal character. 2. In spinal embryos (decapitated on the second day of incubation) there was no such activating effect, demonstrating that it is associated with supraspinal components of the CNS. 3. In chronic administration from the fourth day of incubation (1.55 +/- 0.24 mg/kg e.w./24h), beta-CCE led to reduced development of spontaneous motility. The effect was concentrated in the period between the fourth and eighth day of incubation. The chronic administration of beta-CCE augmented the activating effect of metrazol and weakened GABA-inhibition of spontaneous motility. 4. On the basis of their findings, the authors express the hypothesis that the benzodiazepine beta-CCE-sensitive component of the complex GABA receptor evidently already functions from the beginning of the second half of incubation of chick embryos.

Animals↗
PubMed1991

[The standardization of colloid osmotic pressure of blood substitutes with a perfluorocarbon base].

Besides a number of other characteristic features the colloidal osmotic pressure of blood substitutes is of importance, since it regulates the physiological balance between the intra- and extravascular fluid content. The colloidal osmotic pressure in blood is determined predominantly by the albumin fraction. The entropy increase on diluting albumin which, can't pass semipermeable vascular walls of the intravascular substances are used in blood substitutes to maintain the colloidal osmotic pressure. Their selection and appropriate are of great importance for the efficiency of blood substitutes.

Blood Substitutes↗
PubMed1991

[Rheological behavior of blood substitutes with a perfluorocarbon base].

Oxygen uptake and desoxygenation in blood take place in the capillary system of the organism so that flow characteristics of blood substitutes should be adapted to that of microcirculation. Therefore, appropriate viscosity of blood substitutes is required. In addition to this, studies on the viscosity of blood substitutes made on the basis of perfluorocarbons are also of interest for considering the deemulsificability during circulation. Viscosity measurements carried out on highly polymerized dextran solutions determining the colloid osmotic pressure in blood substitutes, perfluorocarbon emulsions as oxygen carriers, blood as well as mixtures of these components showed that the rheological behaviour of blood substitutes examined did not lead to organic disorders.

Blood Substitutes↗
PubMed1991

[The toxicity of surface-active substances for emulsifying perfluorocarbon compounds as components of blood substitute preparations].

Perfluorocarbons are insoluble in water. For being used as oxygen carriers in blood substitutes they therefore have to be emulsified. Using surfactants in the living organism a compromise on the emulsifying effect and toxicity is to be made, since good emulsifiers do also affect biological membranes. The influence of molecule parameters of surfactants on toxicity was studied in this paper.

Animals↗
PubMed1991

[The dynamics of bone apposition in different animal species--a comparative study].

The time of the bone apposition was compared in rats, rabbits and guinea pigs with the aid of enzyme-activity measurements, determination of the proportion of minerals and the judgment of the cell generation. For this intention a defect was made in the distal femur epiphyses at the three species. The animals were observed for a term of 15 weeks. The results showed little differences with regard to the speed of the bone apposition in the three called species. The bone metabolism of rats was higher than those of the other ones. A clear reference value for the enzyme activity to a define point of time of the mineralization could not be ascertained.

Alkaline Phosphatase↗
PubMed1990

[Efficacy of Pygeum africanum extract in the medical therapy of urination disorders due to benign prostatic hyperplasia: evaluation of objective and subjective parameters. A placebo-controlled double-blind multicenter study].

The efficacy of an extract of Pygeum africanum in the treatment of micturitional disorders due to benign prostatic hyperplasia was tested in a multicentre double-blind trial versus placebo. Capsules containing 50 mg of Pygeum africanum extract or placebo were administered at a dosage of 1 capsule in the morning and 1 capsule in the evening over a period of 60 days. 263 patients were included in this study, which was carried out in 8 centres in Germany, France, and Austria. Evaluation was mainly based on quantitative parameters such as residual urine, uroflowmetry and the precise monitoring of diurnal and nocturnal pollakiuria. Treatment with the Pygeum africanum extract led to a marked clinical improvement: a comparison of the quantitative parameters showed a significant difference between the Pygeum africanum group and the placebo group with respect to therapeutic response. The characteristic subjective symptoms of micturitional disorders, which were evaluated by the patients in a qualitative manner, were also significantly improved by administration of Pygeum africanum extract. Overall assessment at the end of therapy, showed that micturition improved in 66% of the patients treated with Pygeum africanum extract, as compared with an improvement of 31% in the placebo group. The difference was significant at the statistical level of p less than 0.001. During therapy with Pygeum africanum extract, gastrointestinal side effects occurred in 5 patients. Treatment was discontinued in three of those cases.

Double-Blind Method↗
PubMed1990

[Automatic blood group determination in the ABO- and Rh-system using conductometry].

A method was developed and tested on the basis of conductometry for determining blood group-specific agglutinates in the AB0 and Rh-system (D). By comparing the measured particle numbers before and after administration of specific antisera or test erythrocytes and objective evaluation can be made whether agglutination has occurred or not. The calculated degrees of agglutination were compared depending on the method, sex, and age of patients. The method can be automated.

ABO Blood-Group System↗
PubMed1989

[Chemoluminescence study of the influence of phagocytosis of peripheral blood leukocytes using a perfluorocarbon-containing blood substitute].

In an animal experimental model (rats) the influence of which model substances for blood substitution of GDR origin may have on the phagocytosis behaviour of leukocytes of the peripheral blood was investigated by means of luminol-amplified chemoluminescence. After applying the model substance in an amount corresponding to 10% of the circulating blood volume a reversible increase of luminol-amplified chemoluminescence could be observed. The values referred to the portion of neutrophilic granulocytes, however, showed no significant differences compared to the control groups. The opsonizing capacity of the serum towards cymosan revealed a temporary deficit after applying blood substitution substances of GDR origin. The conclusion is drawn that the functions of leukocytes of the peripheral blood recorded by the applied method are not depressed by the model substances used.

Animals↗
PubMed1989

[The development of drug utilization with special reference to demographic factors].

Possible influences of demographic changes in the Federal Republic of Germany on future expenditures for medication have been investigated using population models from the Federal Statistical Office and data concerning the structure of current drug expenditures of the health insurance system. In addition the former contribution of demographic changes to the development of drug expenditures has been estimated using retrospective analysis. The study demonstrates that a constant supply with medicines would require an increase of expenses of 0.6% per year until 2,000 AD due to demographic changes, assuming other conditions remain constant. Development since 1957, however, shows that demographic influences are of relatively low importance for the development of total drug expenditures. During the last decade the total growth of costs for medicines was 6 times higher than that which would have been expected due to demographic changes alone. Further comparisons with the growth rate of the gross national product (GNP) demonstrate that since 1975 growth of drug expenditures parallels growth of GNP. The price indices for pharmaceutical products and for cost of living developed in a parallel way during the same period of time.

Age Factors↗
PubMed1988

[Peri-implantation enzymes and mineralization in bone tissue after implantation of bioactive vitroceramic material--a method for biomaterial testing for hard tissue substitutes. 2. Results of studies of vitroceramics and their modification by the admixture of metal oxides].

The activities of the alkaline and the acid bone phosphatases as well as the concentrations of calcium and phosphorus were measured in the periimplantal tissue of the rat femur bone after implantation of the vitroceramic Ap 40, the metal oxide stabilized vitroceramics Ap 40 A and Ap 40 Z, as well titanium after 2, 10, and 15 weeks. The incorporation of the vitroceramic Ap 40 turns out like a primary bone fracture healing. The implants Ap 40 A and Ap 40 Z are a compromise with a higher stability and the osteogenesis induced effect is preserved, but is belated in contrast to Ap 40.

Acid Phosphatase↗