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Biomedical subjects

P Köhler

Publications and source records attributed to P Köhler.

At least 73 records · Page 4Linked to original sources
PubMed1989

[The importance of the determination of intraerythrocytic sodium for the differential diagnosis and the control of the progression of essential hypertension].

Intraerythrocytic sodium concentration in 432 patients with essential hypertension under antihypertensive therapy with various drugs was determined. Aim of this investigation was to detect the importance of such finding for diagnosis and control of essential hypertension. According results presented intraerythrocytic sodium should be investigated in beginning of each antihypertensive therapy and later in intervals of 6-8 months to control effectiveness of therapy.

Adult↗
PubMed1988

A new in-built device for one-point stepless prosthetic alignment.

The authors have developed a new in-built device for alignment of below-knee prostheses. The device allows one-point, stepless adjustment of angle and slide, independently of each other and also after completed prosthetic manufacture. Principally, the device consists of a half-sphere for angle adjustment and a plate for both slide adjustment and socket application. If the socket has to be exchanged, the whole device can be re-used, apart from the plate, which forms part of the socket bottom. The device is light, compact, cosmetically easy to cover and cheap. The design incorporates a combination of the most important facilities for alignment as well as for exchange of socket, and by its simplicity seems to offer major advantages over other designs.

Artificial Limbs↗
PubMed1987

Fasciola hepatica: action in vitro of triclabendazole on immature and adult stages.

Under in vitro conditions in a balanced salt solution, triclabendazole was found to accumulate in significant amounts in both immature (3 week old) and adult Fasciola hepatica. A viable parasite was needed to concentrate the drug, but a high percentage of the compound was also bound by the dead worm. The drug could penetrate into liver flukes even when the oral route had been closed off by ligation, indicating that the drug can be taken up by transtegumentary absorption. A 24 hr exposure to triclabendazole, at 10-25 microM concentrations, was found to result in a strong inhibition of the parasite's motility. This effect was paralleled by dramatic changes in the worm's resting tegumental membrane potential. The onset of these actions was found to develop very slowly, and high drug levels had to accumulate within the parasite to initiate its immobilization. In addition to drug concentration and incubation time, physiological alterations observed were also dependent on other culture conditions, such as the presence or absence of serum albumin and the drug tissue/medium ratio. Biochemical examinations showed that triclabendazole significantly stimulated glucose derived acetate and propionate formation by adult liver flukes. Adenosine triphosphate levels were not changed even in the presence of high triclabendazole concentrations (25 microM). Likewise, the activities of various membrane associated adenosine triphosphatases were not altered by the drug. However, the ability of the drug to inhibit colchicine binding to microtubular protein purified from adult liver flukes suggested an interference of the drug with microtubular structure and function.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetates↗
PubMed1987

Incorporation of nonviable bone grafts. Autoclaved autogeneic and frozen allogeneic bone grafts compared in the rabbit.

In 14 adult rabbits the middle third of the ulna was resected bilaterally followed by reimplantation of resected bone after autoclaving on one side and transplantation of allogeneic bone on the other. In 7 animals the bilateral implants were supplemented with allogeneic bone matrix. The reconstructions were studied in vivo by serial radiography, scintigraphy, and bone mineral determination. The animals were killed at 16 weeks, and the ulnar reconstructions further studied by high resolution radiography, 45Ca autoradiography, and histology. In both types of nonsupplemented reconstructions, new bone formation was poor; nonunion occurred in three out of seven autoclaved reimplants and in five out of seven allogeneic transplants. Supplemented with allogeneic bone matrix, both types of reconstructions exhibited abundant new bone formation and complete incorporation of all implants. Enhancement of new bone formation is probably more important than the type of nonviable bone graft chosen for reconstruction of large skeletal defects.

Animals↗
PubMed1987

Diaphyseal reconstruction by autoclaved bone. Reimplantation experiments in rabbits.

In 8 adult rabbits, reconstruction of large humeral defects by reimplantation of resected, autoclaved bone supplemented with allogeneic bone matrix was investigated with respect to incorporation (radiography, histology), bone metabolic activity (scintigraphy, autoradiography), and strength (torsional test). Radiography showed that seven out of eight implants were incorporated at 3 months. Scintigraphy and autoradiography disclosed bone metabolic activity in the reconstructions still 8 months postoperatively. Histological investigations evidenced abundant new viable bone that partially had replaced the implants at 8 months. The torsional test disclosed that the strength of the reconstructions was 84 per cent of normal 8 months after reimplantation. Our experiment supports the concept of reimplantation of autoclaved tumorous bone supplemented with allogeneic bone matrix in reconstruction after local resection.

Animals↗
PubMed1987

Incorporation of autoclaved autogeneic bone supplemented with allogeneic demineralized bone matrix. An experimental study in the rabbit.

Resected, autoclaved, and reimplanted bone supplemented with allogeneic demineralized bone matrix (DABM) was compared with nonsupplemented bone in the reconstruction of bilateral ulnar defects in seven adult rabbits. The reconstructions were studied in vivo with the use of serial radiography, scintigraphy (99mTc-MDP), and bone mineral determination. After sacrifice at 16 weeks, the ulnar specimens were analyzed with the use of high-resolution radiography, autoradiography (45Ca), and histologic study. Scintigraphically, the uptake was significantly higher in the DABM-supplemented implants during the entire investigation. Bone mineral content was significantly higher at four and eight weeks in the DABM-supplemented implants, compared with the nonsupplemented implants, but later it equalized. New bone formation, as reflected by 45Ca incorporation, still occurred at 16 weeks in both types of implants, but it was more intense in the DABM-supplemented ones. Radiography and histologic analysis showed more new bone in the DABM-supplemented reconstructions than in the nonsupplemented ones. High-resolution radiography showed complete incorporation of all seven DABM-supplemented implants, whereas there was nonunion in five of seven nonsupplemented reconstructions. The current study indicates that resected, autoclaved, and reimplanted diaphyseal segments supplemented with demineralized allogeneic bone matrix incorporate better than nonsupplemented implants of autoclaved autologous bone.

Animals↗
PubMed1986

Progress in molecular parasitology.

Substantial progress has been made in the last ten years in understanding the structural and functional organization of parasitic protozoa and helminths and the complex physiological relationships that exist between these organisms and their hosts. By employing the new powerful techniques of biochemistry, molecular biology and immunology the genomic organization in parasites, the molecular basis of parasite's variation in surface antigens and the biosynthesis, processing, transport and membrane anchoring of these and other surface proteins were extensively investigated. Significant advances have also been made in our knowledge of the specific and often peculiar strategies of intermediary metabolism, cell compartmentation, the role of oxygen for parasites and the mechanisms of antiparasitic drug action. Further major fields of interest are currently the complex processes which enables parasites to evade the host's immune defense system and other mechanisms which have resulted in the specific adaptations which enabled parasites to survive within their host environments. Various approaches in molecular and biochemical parasitology and in immunoparasitology have been proven to be of high potential for serodiagnosis, immunoprophylaxis and drug design.

Animals↗
PubMed1986

Killing of Giardia lamblia by human milk is mediated by unsaturated fatty acids.

Giardia lamblia trophozoites were killed in vitro by 1% fresh human milk in the presence of bile. A similar effect was achieved in the absence of bile with milk which had been stored for at least 24 h at 6 degrees C. This killing activity was found to be caused by unsaturated fatty acids. Depending on their chain length and the number of double bonds, the concentrations of unsaturated fatty acids required for a 50% killing effect varied between 15 and 36 microM. The saturated palmitic and stearic acids, as well as various substances related to fatty acids, showed only a slight killing effect. Bile enhanced and serum suppressed the action of fatty acids on the protozoan parasite. The possible site of interference of unsaturated fatty acids within G. lamblia and the reasons for the obvious inefficacy of dietary fatty acids in giardiasis are discussed.

Adult↗
PubMed1986

Physical properties of autoclaved bone. Torsion test of rabbit diaphyseal bone.

Structural properties of autoclaved diaphyseal bone in the rabbit were investigated by torsional test. Heat propagation into the bone was studied by means of thermocouples. The torsional test included 54 pairs of diaphyseal bones. Autoclaving was performed to the same degree of sterilization, although with variations of time and temperature. Standard autoclaving at 121 degrees C for 20 min was found to cause a moderate decrease (23 per cent) in torsional strength. The decrease was more pronounced (35 per cent) for bones autoclaved at 110 degrees C for 255 min and less (9 per cent) for those autoclaved at 131 degrees C for 2 min. Heat propagation into bone during autoclaving proved to be rapid at both 121 degrees C and 131 degrees C, indicating that complete, uniform sterilization of diaphyseal bone may be performed to an accurate, predetermined degree. Diaphyseal bone subjected to standard autoclaving remains mechanically adequate for skeletal substitution. Reimplantation of autoclaved tumorous bone might provide a simple combined means for tumor devitalization and subsequent reconstruction.

Animals↗
PubMed1985

Respiration and energy conservation in the filarial worm Litomosoides carinii.

The average rate of endogenous respiration of intact Litomosoides carinii was 2.24 muatom O min-1 g-1 worm wet wt. No significant difference was observed in respiration capacities between male and female worms. Rates of oxygen uptake decreased progressively during disruption and fractionation of the parasite tissue and very few respiration capabilities remained in the mitochondrial fraction. Added substrates increased the respiratory rates of the intact filariid and cell-free extracts by a factor of 1.4 to 2.3, depending on the tissue system and substrate species used. Rotenone and cyanide strongly inhibited respiration in all incubations, whereas antimycin A, in most cases, suppressed oxygen consumption only partially. ATP conservation in cell-free extracts of L. carinii, as determined by the incorporation of 32Pi into the organic phosphate fraction, was twice as high in the presence of air as under an atmosphere of nitrogen. Anaerobically, rates of phosphorylation in these extracts were similar to the amounts of lactate. Phosphorylation in mitochondria isolated from the filarial worm was supported by malate, succinate, pyruvate and TMPD/ascorbate, whereas L-glutamate and beta-hydroxybutyrate exhibited only little or no effect, respectively. P/O ratios for pyruvate-supported oxidative phosphorylation were found to approach a value of 3. Electron transport inhibitors, oligomycin and 2,4-dinitrophenol strongly inhibited substrate-dependent mitochondrial phosphorylation. The data of the present investigation, together with other recent findings made by the same authors, have provided evidence that in L. carinii mitochondria a mammalian-type of respiratory system capable of carrying out oxidative phosphorylation is functional. It seems likely that this respiration-dependent chemical energy, proceeding in addition to that generated through fermentation processes, may be vital for muscular contraction and survival of this filarial parasite.

Adenosine Triphosphate↗
PubMed1985

The strategies of energy conservation in helminths.

From the above discussion it is quite obvious that the bioenergetics in helminths are different in many ways from those found in higher organisms. All adult helminths appear to be able to consume oxygen when it is available but none of them can use it to drive the pathways of complete substrate degradation, like typical aerobic organisms, as a major strategy for energy generation. These properties hold also true for those worms residing in a highly aerobic environment, such as the blood stream or the muscle and lung tissues. Although in a number of recent studies oxygen was found to play apparently a greater role in the bioenergetics of adult helminths than originally thought, energy-generating mechanisms in adult worms seem to place greater emphasis on fermentations and anaerobic electron transport processes. These exhibit relatively low energy conservation efficiencies and result in the formation of a variety of organic end products, most of which must be excreted. The obvious correlation between the type of bioenergetic strategy operative in a particular helminth species and its environmental conditions is not well understood. The increased capacity to generate chemical energy and key metabolites of helminths possessing multiple fermentations and anaerobic respirations may give the organism greater versatility and metabolic flexibility to respond to the environmental changes observed in its corresponding habitat. Other helminths, such as schistosomes and filariids, which have continuous access to a fairly constant nutrient supply, were found to depend primarily on the more inefficiently functioning and primitive strategy of glycolysis for energy production. The reason for the occurrence in helminths of limited oxidative capacities is not completely clear. It may be assumed that the variety of alternative anaerobic pathways have evolved in response to the lack of a circulatory system and/or to the specific, often peculiar, environmental conditions prevailing in most parasitic habitats. An alternative idea put forward by Barrett [8] is that helminth metabolism represents a form of biochemical economy. Most endoparasites have an abundant supply of food and swim as if in a land of Cockain, obviously without any need to extract a maximum amount of chemical energy from the nutrients they take up. On the other hand, the fact that free-living and other larval or juvenile stages of helminths often have a typical aerobic bioenergetic pattern is a clear indication that the DNA of these organisms carries the genetic message for all the enzymes involved in complete substrate degradation.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenosine Triphosphate↗
PubMed1983

The localization of fumarase and malic enzyme in muscle mitochondria of Ascaris suum.

The distribution of fumarase and malic enzyme in Ascaris suum muscle mitochondria was investigated by employing digitonin fractionation techniques. The ability of these procedures to resolve the various submitochondrial fractions (intracristal space, inner membrane, matrix and inner membrane-matrix particles) was verified by electron microscopy and the distribution of appropriate marker enzymes. From the data obtained, it is concluded that fumarase in Ascaris muscle mitochondria is located solely within the matrix compartment and is not present within the intracristal space as reported earlier by other authors (Rew and Saz (1974) J. Cell. Biol. 63, 125-135). In agreement with previous findings malic enzyme in the nematode organelle appears to be associated with both soluble compartments. The implications of these findings to the parasites' mitochondrial metabolism are discussed.

Animals↗
PubMed1982

[Drug lowering of the HDL concentration in the serum of cardiologically treated patients].

The connection between decreased concentration of HDL-cholesterol in the serum and increased risk of arteriosclerosis has attracted the attention to such sizes of influence which are able to decrease the HDL-cholesterol-concentration. In these cases the question is asked, whether the analytic reliability of the techniques which are at the disposal for the estimation of HDL-cholesterol is sufficient for the recognition of the changes of the concentration to be expected. To the sizes of influence belong medicaments which cannot be fancied away in the therapy of cardiovascular diseases; thus the beta-receptor blockers talinolol and propranolol. The examination of 118 cardiologically treated patients yields the result that there is no particular risk of the patients treated by means of these medicaments, since an essential decrease of the HDL-cholesterol-concentration could not be proved.

Adrenergic beta-Antagonists↗