Vibrational dependence of negative-ion formation by dissociative attachment of low-energy electrons.
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Journal Article↗
Biomedical subjects
M Keil
Publications and source records attributed to M Keil.
Circulating ICAM-1: novel parameter of renal graft rejection.
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Biomarkers↗
[Experimental studies on the systemic toxicity of dental alloys free of precious metals].
The systemic toxicity of five non-precious dental alloys was evaluated by help of an animal study. The pulverized dental alloys, filled in gelatine capsules, were orally administered to laboratory rats using a special esophageal application device. For each alloy examined randomized groups of ten experimental animals and ten control animals were used. For a period of seven days the experimental animals received daily 1000 mg alloy powder per kilogram body-weight. The animals of the control groups received daily empty gelatine capsules (placebo application). After two weeks all animals were killed and autopsies of the animals were performed. Histopathologic examinations of the lungs, kidneys, liver, small intestine and large intestine of all animals were done. With statistic significance (p less than 0.001) rats whom nickel-chromium alloys were administered orally showed serious pathologic reactions more frequently than placebo-treated control animals. Nickel-chromium alloys containing beryllium and/or gallium caused the strongest organic lesions. In contrary to this a dental cobalt-chromium alloy showed a very low systemic toxicity. The results of the study underline that preclinical toxicity testing of dental alloys is necessary in order to avoid systemic toxic lesions in man.
Administration, Oral↗
Quantification of keratinolytic activity from Dermatophilus congolensis.
The bacterium Dermatophilus congolensis is the causative agent of pitted keratolysis, a skin disease. Infection occurs mainly in keratinized tissues and it is necessary for the organism to produce and excrete exoenzymes which are able to degrade keratin. We investigated the amount of keratinase liberated using Keratinazure as substrate and the fungal protease XI as standard. When compared with uninoculated samples, D. congolensis liberated significant amounts of keratinase during a 12-day incubation period with this substrate. An equivalent of 15 units of protease (keratinase) was produced by 10(7) colony-forming units of D. congolensis during a 12-day period at 37 degrees C. We consider the extracellular proteolytic activity of this bacterium to be responsible for keratinized tissues being the main sites of infection.
Actinomycetales↗
[Histomorphometrical studies on the histocompatibility of dental alloys].
The local toxicity (histocompatibility) of 12 dental casting alloys was examined with the aid of quantitative histomorphometry after intramuscular implantation in rabbits. For each alloy examined and each implantation period (2, 4, 8, 12 weeks) two rabbits were used. In each animal eight grooved cylindrical implants of the same alloy were installed in the left paravertebral muscle. Histomorphometric measurements of the thickness of the connective tissue encapsulating the implant were carried out to assess the degree of foreign body reactions caused by the alloys. Histomorphometry revealed significant differences in the thickness of the soft tissue capsule in relation to the length of the implantation period. The study also demonstrated significant differences in capsule thickness for the different dental alloys at equal implantation periods. Quantitative histomorphometry of the thickness of the connective tissue capsule around intramuscularly implanted dental alloys proved to be suitable for examining the histocompatibility of those materials.
Animals↗
[Histocompatibility of implant materials--animal model criteria and findings].
The histocompatibility of the dental implant materials titanium and aluminium-oxideceramics was examined with the aid of quantitative histomorphometry and semiquantitative histopathologic methods after intramuscular and subcutaneous implantation in rabbits and guinea-pigs. Of each material cylindrical and spindel-shaped specimens with rough and smooth surface conditions were implanted for different implant periods (1, 2, 4, 8, 12 weeks). The local tissue reactions caused by the implant materials showed significant differences. Cylindrical implants and/or implants with a rough surface produced, with statistical significance (p less than or equal to 0.001) the strongest tissue reactions (foreign body reactions). Contrary to this, spindel-shaped and smooth titanium- and Al2O3-ceramic-implants elicited bland tissue reactions. In these cases we found a significant increase in subcapsular adipose tissue (p less than or equal to 0.001) and significantly less thickness of the connective tissue capsule (p less than or equal to 0.001).
Aluminum Oxide↗
[Biocompatibility of precious metal dental alloys].
The local toxicity of three dental gold alloys was examined by help of intramuscular implantation tests in rabbits. For each alloy implantation periods of 1, 2, 4, 8, and 12 weeks were used. The local tissue reactions (foreign body reactions) were judged and graded by use of quantitative histomorphometry. Furthermore specific cellular parameters were examined with semiquantitative histopathologic methods to get an toxicity index for each material. The local tissue reactions caused by the implanted dental alloys were judged in relation to those, caused by biological inert materials (titanium, aluminum-oxide-ceramics) respectively materials with well-known toxic potential (polyvinyl-chloride with toxic aids), after intramuscular implantation in the same animals. Significant differences were found in the tissue reactions caused by the dental gold alloys; an gold alloy with lower noble metal content elicited stronger tissue reactions than both gold alloys with high noble metal content did.
Animals↗
Gene expression during tuber development in potato plants.
Potato tubers are modified stems that have differentiated into storage organs. Factors such as day-length, nitrogen supply, and levels of the phytohormones cytokinin and gibberellic acid, are known to control tuberization. Morphological changes during tuber initiation are accompanied by the accumulation of a characteristic set of proteins, thought to be involved in N-storage (i.e. patatin) or defense against microbial or insect attack (i.e. proteinase inhibitor II). Additionally, deposition of large amounts of starch occurs during tuber formation, which is paralleled by an increase in sucrose synthase and other enzymes involved in starch biosynthesis (i.e. ADP-glucose pyrophosphorylase, starch synthases, and branching enzyme). Potential controlling mechanisms for genes expressed during tuberization are discussed.
Carboxylic Ester Hydrolases↗
Electronic origin of the intermediate phase of NiTi.
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Journal Article↗
Ischaemic damage in gerbil hippocampus is reduced following upregulation of adenosine (A1) receptors by caffeine treatment.
We have used the fact that long-term caffeine treatment upregulates the adenosine receptors, to examine the role of adenosine in ischaemia. Four-week oral treatment with caffeine (0.2% in drinking water) caused a significant (10-17%) increase in the binding of the adenosine A1-receptor ligand [3H]cyclohexyl-adenosine (CHA) to several brain regions, including the hippocampal CA1 area, in Mongolian gerbils. Animals subjected to such treatment exhibited significantly less neuronal damage in the CA1 region following 5 min bilateral carotid occlusion than did control animals (50% of the caffeine-treated animals showed no damage at all compared to 11% in the control group). Our findings provide further evidence for a protective role of endogenous adenosine during ischaemia.
Administration, Oral↗
Both wound-inducible and tuber-specific expression are mediated by the promoter of a single member of the potato proteinase inhibitor II gene family.
A chimeric gene consisting of 1.3 kb of the 5' regulatory region of a member of the potato proteinase inhibitor II gene family, the coding region of the bacterial beta-glucuronidase (GUS) gene and 260 bp of the proteinase inhibitor II 3'-untranslated region containing the poly(A) addition site was introduced into potato and tobacco by Agrobacterium tumefaciens mediated transformation. Analysis of transgenic plants demonstrates systemic, wound-inducible expression of this gene in stem and leaves of potato and tobacco. Constitutive expression was found in stolons and tubers of non-wounded potato plants. Histochemical experiments based on the enzymatic activity of the GUS protein indicate an association of the proteinase inhibitor II promoter activity with vascular tissue in wounded as well as in systemically induced non-wounded leaves, petioles, potato stems and in developing tubers. These data prove that one single member of the proteinase inhibitor II gene family contains cis-active elements, which are able to respond to both developmental and environmental signals. Furthermore they support the hypothesis of an inducing signal (previously called proteinase inhibitor inducing factor), which is released at the wound site and subsequently transported to non-wounded parts of the plant via the vascular system from where it is released to the surrounding tissue.
Journal Article↗
Wound expression of a potato proteinase inhibitor II gene in transgenic tobacco plants.
A potato proteinase inhibitor II gene was transferred into tobacco plants using Agrobacterium/Ti-plasmid-mediated gene transfer techniques. Whereas no or little expression of the proteinase inhibitor II gene could be detected in non-wounded leaves, high levels of proteinase inhibitor II mRNA were detected in leaves of several transgenic tobacco plants after mechanical wounding as well as after treatment of detached leaves with oligosaccharides. Wounding of a leaf also led to a systemic induction in non-wounded leaves as well as non-wounded stem, and roots. RNA-protection experiments showed that the transcription of the proteinase inhibitor gene in transgenic tobacco plants was initiated at the same nucleotide as that of the original gene. These observations demonstrate that although no proteinase inhibitor II homologous gene can be detected in tobacco, this plant nevertheless has the capacity to regulate the expression of the potato gene in the same complex manner as in the case of potato.
Blotting, Southern↗
Effect of theophylline on ischemically induced hippocampal damage in Mongolian gerbils: a behavioral and histopathological study.
We investigated the influence of the adenosine antagonist theophylline on the degree of hippocampal cell damage in the Mongolian gerbil following brief periods of forebrain ischemia. Male gerbils were randomly divided into nine groups. Ten minutes before surgery, four groups, which were later subjected to 1, 2, 3, or 5 min of bilateral carotid occlusion under halothane anesthesia, received theophylline (30 mg/kg, p.o.). Four groups served as nontreated ischemic controls; the ninth group was used to measure theophylline serum concentration. Neurological symptoms were classified by using a behavioral score. Fourteen days after ischemia, the brains were removed, and the hippocampus was histologically examined "blind" for the degree of cell damage in the CA1 sector, which was expressed as a semiquantitative histopathological score. There were no behavioral or histological abnormalities in either the control or theophylline group with 1 min of ischemia. With increasing duration of ischemia, the neurological symptoms worsened and the number of necrotic pyramidal cells increased significantly. The pretreatment with theophylline only moderately aggravated the neurological symptoms, whereas it enhanced the ischemic cell damage significantly. The results are discussed with respect to recent findings that theophylline may block putatively protective effects of endogenous adenosine, whose concentration in the brain is known to rise significantly during ischemia.
Adenosine↗
Primary structure of a proteinase inhibitor II gene from potato (Solanum tuberosum).
The isolation and characterization of a genomic clone encoding proteinase inhibitor II of potato (Solanum tuberosum) is described. The structure of this gene was determined by sequencing a genomic fragment of about 2 kb containing the entire RNA coding as well as about 900 nucleotides of the 5'-upstream and 250 nucleotides of the 3'-downstream region. The transcription start site was determined by RNase protection experiments. The comparison of the genomic sequence with cDNA sequences reveals the presence of one intron with a length of 117 nucleotides. The genomic clone contains an open reading frame of 462 nucleotides allowing for a protein of 154 amino acids. The proteinase inhibitor II gene displays typical features of eucaryotic genes. The sequence TATAAA is found 26 nucleotides upstream of the transcription initiation site and the sequence CAAAT at position--103. In the 3'-region the sequence AATAA is found 33 nucleotides in front of the poly-A addition site.
Amino Acid Sequence↗
Morphological findings in pancreatectomized dogs with an implanted insulin dosing device: tissue reaction to the pump housing and to the vascular catheter.
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Animals↗
Vitamin D-induced myocardial lesions and the protection by carbocromen.
Effects of high doses of vitamin D on rat hearts were investigated 72 h after the administration of 500 000 U/kg. Histological examination showed disseminated focal necrosis with reactive round cell and granulocytic infiltration in the heart. The calcium content was increased by about 70%. These findings indicate vitamin D-induced myocardial lesions. Heart mitochondrial calcium binding and uptake activities were lower than in control animals. Na+-K+-ATPase activity of heart washed particles was reduced by the treatment with vitamin D whereas neither calcium binding and uptake activities of cardiac sarcoplasmic reticulum nor myofibrillar ATPase activity were affected. Carbocromen (20 and 100 mg/kg/d) treatment reduced vitamin D-induced decreases in mitochondrial calcium accumulating ability and Na+-K+-ATPase activity of heart washed particle, suggesting a beneficial effect of carbocromen against vitamin D-induced cardiac injury.
Animals↗
[Effects of molsidomine and nitroglycerin on the regional blood flow in the normal and acutely ischemic myocardium (author's transl)].
In anaesthetized dogs regional myocardial blood flow (radioactive particle distribution technique) and several haemodynamic parameters were measured before and after acute ligation of left descending coronary artery. By injection of N-carboxy-3-morpholino-sydnonimine ethylester (molsidomine, Corvaton) or infusion of nitroglycerin it was tried to influence blood flow of the infarcted areas of the myocardium. 1. Ligation of the coronary artery induces myocardial infarction of anterior wall, predominantly restricted to the endocardial portions of the heart muscle. 2. Molsidomine and also nitroglycerin do not change overall blood flow of the heart in the sense of vasodilation. 3. In the infarcted area the ratio: blood flow of endocardial layers to blood flow of epicardial layers, is improved by molsidomine. 4. The positive effect of molsidomine becomes clearer in the border zone of infarction. Nitroglycerin remains without effect. 5. The effects of the compound molsidomine are explained by stronger action on extravascular factors of colonary vascular resistance (decrease in enddiastolic pressure).
Animals↗
[Autoradiographic studies on the distribution of 14C-piracetam in the simian brain].
Autoradiography of the brain of the monkey Callithrix jacchus 2 and 6 h after oral application of 200 mg 14C-piracetam/kg (2-oxo-pyrrolidine-l-acetamide-2-14C) shows that the drug is preferably concentrated in the cortex of cerebrum and cerebellum. This specific affinity of piracetam which was observed earlier in dog and rat is thus confirmed in the primate and seems to be species independent. Beside the dominant cortical concentration there is a characteristic storage of piracetam in many nuclei of other brain areas, for instance, nucleus caudatus, hippocampus, n. anteriores thalami, n. dorsales thalami, corpus geniculatum laterale and mediale, corpora mamillaria, nucleus supraopticus, substantia grisea centralis, colliculi superiores and inferiores. Furthermore piracetam is stored in the blood vessel wall of the brain over 6 h. The hypophysis and pineal body take up radioactivity intensively.
Animals↗