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Biomedical subjects

R Reiche

Publications and source records attributed to R Reiche.

At least 19 recordsLinked to original sources
PubMed2003

XPS investigations of thin tantalum films on a silicon surface.

Ultra thin tantalum-based diffusion barriers are of great interest in copper metallisation technology. Even the smallest amounts of copper that diffuse into the active silicon regions on a microprocessor will alter their semiconducting properties thus leading to failure of the device. In the present work Ta films were deposited on silicon by electron beam evaporation and magnetron sputtering. The background of this study is investigation of interface formation, which is expected to have substantial influence on the properties of thin Ta films. All experiments were carried out under UHV conditions. This was necessary because Ta is a very reactive metal and is readily oxidized even at low oxygen partial pressure. The Ta4f peak, as a sensitive indicator of the chemical state, was analysed and compared to that for standard samples. Silicide formation is assumed to occur at the Ta/Si interface.

Journal Article↗
PubMed1995

[From inside to outside? Blind alleys in the discussion of psychoanalysis and society].

The attempt first instituted by Freud to use the instruments of psychoanalysis to improve understanding not only of the individual but also of society as a whole has a long tradition, particularly in Germany. Reviewing the last thirty years of discourse on the range of the applicability of psychoanalysis in this context, the author comes to the conclusion that the fruits of this discussion are negligible. Reiche distinguishes five major lines of discourse to illustrate this failure to establish the relevance of a psychoanalytic approach to illuminating the "out-side" world: the first is one of assimilation and desiccation, reference here being to psychoanalytic culture critique; the second a pathological reaction of collective grieving bound up with the Critical Theory; the third the aggressive rebuffs levelled at psychoanalytic insights by systems theory; the fourth a line of devaluation and usurpation as represented by post-structuralism and deconstructionism. In the fifth and final strand of psychoanalytic application discourse discernible in the theory of communicative action, the author discerns a tentative new rapprochement between sociology and psychoanalysis. The author's final conclusion is that psychoanalysis is suitable for the perspective on the inside world, while the outside world is beyond the scope of psychoanalytic theory.

Freudian Theory↗
PubMed1992

Fate and effects of the insecticide Dursban 4E in indoor Elodea-dominated and macrophyte-free freshwater model ecosystems: II. Secondary effects on community structure.

Secondary effects of a single dose of the insecticide Dursban 4E (active ingredient chlorpyrifos) were studied in indoor experimental freshwater ecosystems intended to mimic drainage ditches. Two experiments were performed, one in which all model ecosystems were dominated by the macrophyte Elodea muttallii, and one using systems devoid of macrophytes. In the Elodea-dominated and macrophyte-free model ecosystems, populations of primary producers, herbivores, carnivores and detritivores were indirectly affected via the loss of populations of Arthropoda as a direct result of insecticide application. However, the taxa in which secondary effects were observed differed considerably between these two types of model ecosystem. In macrophyte-dominated systems secondary effects were observed on populations of periphytic algae, the macrophyte Elodea nuttallii, the gastropod Bithynia tentaculata, Turbellaria, and sediment dwelling Oligochaeta. In open water systems it were populations of phytoplankton, the rotators Polyarthra and Asplanchna, bivalves (Sphaeriidae), Hirudinea, sediment dwelling Oligochaeta, and that of the isopod Proasellus coxalis in which secondary effects were observed. In aquatic ecosystems the presence or absence of a well-developed macrophyte vegetation may be a very important characteristic that determines the nature and route of secondary effects induced by pesticides. The differences in secondary effects observed between Elodea-dominated and macrophyte-free model ecosystems indicate that the system's structure and trophic dynamics should be taken into account when predicting ecological effects.

Chlorpyrifos↗
PubMed1991

[Have early disorders increased?].

The author rejects the proposition, encountered in some parts of the psychoanalytic and social-science literature, that certain types of disturbances correspond to certain epochs or forms of society. Instead he reminds us of the core of the psychoanalytic theory of representation according to which every formation of inner structure is an individual creative innovation that eludes normative interpretation.

Humans↗
PubMed1990

[Analysis and analyzing as reflected in an empirical study].

The authors compare two investigations--the findings of the prognostic study concerning psychotherapeutic service delivery in the FRG and a follow-up study carried out among the members of the German Psychoanalytic Association. The former showed that high-frequency long-term analysis is the exception rather than the rule, and the findings of the latter differ only slightly from this determination.

Appointments and Schedules↗
PubMed1984

Anticonvulsant effect of primidone in the gerbil. Time course and significance of the active metabolites.

The anticonvulsant effect of primidone was determined in gerbils, in which seizures were elicited by a blast of compressed air, over the time range of 30 min to 18 h after oral administration. ED50s remained fairly constant from 1 to 12 h after administration: 46-73 mumol/kg with the minimal value at 6 h. Of the metabolites, phenobarbital was maximally effective at 2 h after administration (ED50 35 mumol/kg), whereas phenylethylmalondiamide (PEMA) only had a weak anticonvulsant effect (ED50 1.55 mmol/kg at 2 h). By determination of primidone and its active metabolites in plasma and brain at 1, 4 and 12 h after administration of the respective ED50s, it could be shown that unchanged primidone is mostly responsible for the anticonvulsant effect of the first hours, but, at 12 h, only phenobarbital could be detected in both tissues. PEMA could not be detected in brain. From the effective brain concentrations at different times it could be calculated that primidone and phenobarbital have the same anticonvulsant potency on a molar base in the gerbil. The concentrations necessary to control seizures in this model were considerably lower than those needed to suppress convulsions in maximal seizure models in mice and rats.

Administration, Oral↗
PubMed1983

Anticonvulsant potency of common antiepileptic drugs in the gerbil.

In gerbils, 'minor' (myoclonic) and 'major' (clonic-tonic) seizures were induced by blowing at the animals with compressed air. The anticonvulsant ED50 of the following drugs was determined after oral administration against both types of seizures: phenytoin, phenobarbital, carbamazepine, sodium valproate, ethosuximide, and diazepam. Valproate, ethosuximide, and diazepam were most potent against 'minor' seizures which could not or only partially be suppressed by phenytoin or carbamazepine, respectively. The 'grand mal' drugs phenytoin, phenobarbital, and carbamazepine were, on the other hand, more potent against 'major' than against 'minor' seizures. When phenobarbital was administered for several days, a strong induction of hepatic microsomal enzymes occurred.

Animals↗
PubMed1983

High anticonvulsant potency of gamma-aminobutyric acid (GABA)mimetic drugs in gerbils with genetically determined epilepsy.

Seven GABAmimetic drugs, namely cetyl gamma-aminobutyric acid (cetyl GABA), 4,5,6,7-tetrahydroisoxazolo [5,4-c]pyridine-3-ol, progabide, aminooxyacetic acid, alpha-acetylenic GABA, (-)-nipecotic acid ethyl ester and (+/-)-cis-4-hydroxynipecotic acid methyl ester, were tested for their potency to block "major" (generalized clonic-tonic) seizures in gerbils, induced by blowing at the animals with compressed air. Valproic acid was included as a reference standard. All drugs proved able to protect gerbils from induced seizures. Most effective were 4,5,6,7-tetrahydroisoxazolo [5,4-c] pyridine-3-ol (ED50, 1.3 mg/kg i.p.), aminooxyacetic acid (0.9), cetyl GABA (4.5) and gamma-acetylenic GABA (2.1). A comparison with anticonvulsant ED50 values of common antiepileptics in the gerbil showed that these four GABAmimetics were clearly more potent than phenobarbital, phenytoin, carbamazepine, ethosuximide and valproic acid and were only surpassed in potency by diazepam. Furthermore, most GABAmimetics proved strikingly more active in the gerbil compared with the classical electroshock and pentylenetetrazol seizure models in mice. After administration of gamma-acetylenic GABA, GABA increases in the brain of only about 40% were found sufficient to reach almost complete seizure protection in gerbils. The present data are compatible with the possibility that the GABA system is critically involved in the seizure-prone state in the gerbil.

Alkynes↗
PubMed1983

Relation of anabolic-catabolic glucose utilization in growth-limited cultures of Streptomyces griseus.

Phenotypically different submerged mycelium conserves had been produced from a spore conserve of the HP-strain Streptomyces griseus and proofed in a product formation culture as a test system. The phenotypical characters induced on the base of the genotype proved in a cultivation cycle during 30-34 reduplications of the biomass constant. Employing the HP phenotype we investigated the possibility of economizing the substrate turnover by utilizing the anabolic potential for the synthesis of secondary substances and/or reducing the conservation catabolism during the stationary growth stage. As criteria for that served the stoichiometric turnover equation of the streptomycin biosynthesis and the quotient qO2/qGluc taking at full substrate oxidation the numerical value 6. During the stationary growth stage the relation of maintenance anabolism to maintenance catabolism in addition to the formation as secondary substances is not fixed in the tested HP phenotypes, but in a striking manner variable. The relation of by-product synthesis to secondary metabolism synthesis, too, is variable in the stationary growth stage with constant maintenance catabolism. Due to those response reactions on phenotypical manipulations an economization of the substrate turnover during the product formation stage with stationary growth is not possible in the streptomycin producer Streptomyces griseus.

Culture Media↗
PubMed1983

Antagonism of the 5-HT-induced bronchoconstriction in the cat.

In cats in which bronchoconstriction was induced and maintained by infusion of 5-HT, the bronchodilator effects of ketanserin, a related compound, cyproheptadine, clenbuterol and aminophylline were compared. The novel 5-HT2 antagonists ketanserin and R50970 were active in doses of about 10 nmol/kg, cyproheptadine was about 5 times less potent, but had a longer duration of action. Clenbuterol and aminophylline were only partially effective against 5-HT-induced bronchoconstriction. There was no reliable effect of the 5-HT antagonists against carbachol-induced bronchoconstriction.

Animals↗
PubMed1982

Genetic segregation in a high-yielding streptomycin-producing strain of Streptomyces griseus.

The streptomycin-producing Streptomyces griseus HP spontaneously segregated non-reverting derivatives with altered phenotypes. Clones characterized by increased spore formation and decreased streptomycin production were found. Two other types of derivatives were defective in aerial mycelium and streptomycin formation as well, but differed in the capacity to synthesize a yellow pigment. These derivatives were examined with respect to further properties. The stability of S. griseus HP was investigated in relation to conditions of continuous culture. Both at 26 and 30 degrees C, under glycerol and NH4Cl limitation a rapid segregation and enrichment of streptomycin-non-producing derivatives occurred. At 34 degrees C and glycerol limitation segregation began only after about 35 generations of continuous culture. In NH4Cl-limited chemostats the original strain was stable during 80 generations. In the course of the continuous culture experiments it was shown that the onset of genetic segregation within mycelia can be detected before it becomes obvious in colonies grown from the mycelia. This was achieved by fractionation of the mycelia by protoplast formation and subsequent plating on regeneration medium allowing colony growth and differentiation.

Ammonium Chloride↗
PubMed1981

Interactions between chloramphenicol and intravenous anesthetics.

Chloramphenicol has been reported to prolong the action of barbiturate hypnotics by an inhibition of liver mixed function oxidases. We have studied the importance of this interaction for shortacting intravenous anesthetics the effect of which is terminated by distribution rather than metabolic inactivation. Mice were pretreated orally with 50 mg/kg chloramphenicol as the sodium succinate 1 h before the iv. injection of the anesthetics, and the sleeping times were compared to those of untreated controls. The duration of action of methohexital was prolonged when doses of 15 and 20 mg/kg were injected, but not with the lowest dose of 10 mg/kg. After injection of thiopental (30, 40 and 50 mg/kg) only the medium dose was prolonged the effect of etomidate (3 and 5 mg/kg), but not that of propanidid (60 mg/kg) or ketamine (30 and 40 mg/kg). The results show that the experimental finding of an interaction between chloramphenicol and barbiturates cannot be generalized: It will not play a major role with usual clinical induction doses the effect of which is terminated by distribution, but may be of importance when higher doses are administered.

Anesthesia, Intravenous↗