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Biomedical subjects

W Jahn

Publications and source records attributed to W Jahn.

At least 37 records · Page 2Linked to original sources

Compartment syndrome and shin splints of the lower leg.

OBJECTIVES: The objective of this article is to review and categorize the current knowledge on compartment syndromes (CS) and shin splints (SS), with specific importance relegated to the diagnosis, differential diagnosis and management of these conditions. DATA SOURCES: The bibliographic data sources reviewed are limited to the English language and human content and are from medical and scientific journals, as well as chiropractic and medical texts. A mini-Medline version of Index Medicus was utilized. Terms for indexing included compartment syndromes, shin splints and stress fractures. The bibliographies of the journals selected were then evaluated and, where appropriate, the specific journal or text references regarding diagnosis and management were then reviewed. This information was then included in this article, where useful, to further clarify or reference statements made. CONCLUSION: Differential diagnosis of the acute CS from chronic CS and SS requires clinical methods and imaging procedures. The pathogenesis of the acute CS of the lower leg is associated with external pressure or internal hemorrhage. If the tissue pressure were to rise above 30-40 mm Hg for 4-12 h, irreversible muscular damage would result. Emergency surgical intervention is the only appropriate form of treatment in acute CS. In chronic CS, where elevated pressures exist on a transient basis, influenced by activity, conservative management procedures are felt to be effective. However, if these methods are not helpful, surgical intervention may be necessary. The etiology of pain associated with SS is not associated with compartmental pressure elevations, but rather, results from periostitis occurring along the tibia caused by muscular and tendinous strain associated with inflammation. Conservative management is most appropriate for this disorder, with surgical intervention being an uncommon treatment approach. Although clinical findings are useful in the diagnosis of these disorders, fluid pressure findings may be necessary to fully differentiate acute CS from other disorders. Up until recently, common methods of obtaining pressure measurements of compartments included the use of a needle manometer. More recently, however, a hand-held miniature fluid pressure monitor has been developed that produces reproducible measurements of interstitial fluid, making testing potentially practical for the clinician.

Acute Disease↗

Argiotoxin636 inhibits NMDA-activated ion channels expressed in Xenopus oocytes.

Argiotoxin636, a component of the spider venom of argiope species, was chemically synthesized together with a number of derivatives in order to analyse their blocking activity on mammalian glutamate receptors. Xenopus laevis oocytes injected with rat brain mRNA served as assay system. The results showed that argiotoxin636 had a higher affinity for N-methyl-D-aspartate (NMDA) than for kainate receptors, blocking the corresponding ion channels in a voltage-dependent manner. Modifications of the polyamine tail or the terminal arginine residue strongly reduced the blocking potency. The iodinated monohydroxyl phenylderivatives, however, retained their NMDA-selective binding and could serve as non-competitive antagonists for radioligand binding assays aiding in the biochemical isolation of glutamate receptors.

Animals↗

Novel procedures for derivatization of ribosomes for crystallographic studies.

Undecagold and tetrairidium clusters have been used for the preparation of heavy-metal derivatives of ribosomal particles, necessary for the evaluation of phases in the x-ray structure determination of these large particles. To obtain specific binding, monofunctional reagents of the clusters were prepared and were covalently bound to free sulfhydryl groups on the surface of the ribosome. In addition, a mutant of Bacillus stearothermophilus which lacks one ribosomal protein (BL11) was grown. The heavy-atom clusters were covalently bound to isolated protein BL11, and the modified protein was consequently reconstituted into the mutated ribosomal subunits. Crystallographic data have been collected from crystals of native particles, from the mutated ones, and from the iridium- and gold-derivatized subunits. All these crystal forms are isomorphous within the experimental error.

Crystallization↗

[Age changes of functional nuclear swelling and classes of nuclei in human hepatocytes].

The aim of the study was to describe aging changes in the functional nuclear edema and the classification of human hepatocyte nuclei, by determining three parameters--the size of the nucleus, the relative DNA quantity and the number of chromocenters. For this purpose, karyometry and DNA cytophotometry were performed on 10 human liver preparations. The data obtained was subjected to correlation, cluster and discriminance analysis. The results indicated a reduction in the capacity of liver cells for functional nuclear edema as aging progressed. Whereas at a young age there is only a loose correlation between nuclear size and DNA content, it becomes much stricter later on, partly caused by polyploidization. Cluster analysis, followed by discriminance analysis, is well suited for dividing the nuclei of human hepatocytes into two or three statistical populations provided the nuclear area, DNA quantity and number of chromocenters are all used as characteristics simultaneously. When allowance is made for functional edema, the biological interpretation of clusters from young liver preparations permits meaningful conclusions, but it appears problematic for old preparations. Here it might be more practical to analyze the mixed distributions resulting from a determination of the DNA quantity or nuclear size alone.

Aging↗

[Random sample planning in morphometry].

This report tries to explain principles and presuppositions of planning sample sizes. The aim is estimation of the optimal, that means minimally necessary sample size, justifying an investigation ethically and economically. The problems are complicated because of the necessity of nested sampling or samples within samples. We describe the most important presuppositions using an example of mean value estimation. These are: establishing of demands for exactness, of error probability, and knowledge of variance of the parameters. It is explained in detail by means of binomially distributed variables as we find them in the point counting method.

Humans↗

Antamanide antagonizes the phalloidin-induced negative inotropic effect and blocks voltage dependently the fast outward K+ current in voltage-clamped frog muscle fibres.

The effects of antamanide (10(-14)-10(-5) M) and N-acetyl-secophalloidin (10(-7)-5 X 10(-3) M) a neutral non-toxic derivative of phalloidin, were tested on voltage-clamped single frog muscle fibres. Antamanide protected muscle fibres against the negative inotropic effect of phalloidin but blocked the fast potassium permeability in the same concentration range and the same voltage-dependent manner as did phalloidin. N-Acetyl-secophalloidin exhibited a strongly attenuated blocking effect on K+ permeability in a 1,000-fold higher concentration range than phalloidin. Neither antamanide nor N-acetyl-secophalloidin affected the contractile properties. These results suggest the existence in the frog muscle membrane of a receptor with two sites for phalloidin and antamanide which acts on potassium conductance.

Animals↗

[Biostatistical models in experimental gerontology].

Morphometric measuring values present themselves in a definite distribution which changes in the ageing process. This change of distribution can be clarified by distribution analyses. Another task within the analysis of frequency distributions is the decomposition of mixed distributions, as they may appear in various parameters in the course of life. The linear regression analysis is, for instance, to be used in the verification of sexual divergencies in the process of ageing. An adaptation of non-linear exponential functions to series of measuring values serves, among others, to make evidence concerning the ageing rapidity of the tissues. When in gerontological inquiries at the same time many different characteristics are determined also the degree of their ageing dependency is of interest. This is to be established by means of a special transformation within the factor analysis. Finally the study shows instances for the application of contingency tables in qualitative characteristics and the investigation of their frequency in the process of ageing as well as for the use of the cluster analysis.

Adolescent↗

[Discussion of errors and measuring strategies in morphometry using analysis of variance].

Statistical techniques known as the analysis of variance make it possible for the morphologist to plan work in such a way as to get quantitative data with the greatest possible economy of effort. This paper explains how to decide how many measurements to make per micrograph, how many micrographs per tissue block or organ, and how many organs or individuals are necessary for getting an exactness of sufficient quality of the results. The examples furnished have been taken from measuring volume densities of mitochondria in heart muscle cells and from cell counting in lymph nodes. Finally we show, how to determine sample sizes, if we are interested in demonstration of significant differences between mean values.

Analysis of Variance↗

Alpha-1-antitrypsin: evidence for a fifth PI M subtype and a new deficiency allele PI*Z augsburg.

The phenotypes of the protease inhibitor (PI) alpha-1-antitrypsin have been analyzed by isoelectric focusing on polyacrylamide gels. With improved resolution by a modified procedure it was possible to demonstrate a fifth PI*M suballele. The bands of PI M5 are located between PI M1 and PI M3. In addition, a further deficiency allele similar to PI*Z was found in a female patient with obstructive pulmonary disease. This variant was provisionally named PI Z augsburg (PI Z aug). Family data confirm a simple codominant mode of inheritance for PI Z aug.

Adult↗

Experimental toxicology of ASTA Z 7557 (INN mafosfamide).

The LD 50 of Z 7557 in mice was between 500 and 625 mg/kg after i.v. and around 2310 mg/kg after oral administration. The corresponding LD 10 was around 435 mg/kg (i.v.) or 1100-1250 mg/kg (p.o.), respectively. The LD 50 values in rats were in the range of 250-310 mg/kg after i.v. administration and around 1000-1250 mg/kg if given orally. With repeated daily i.v. injections only 70% of the daily dose contributed to lethality. A second administration of Z 7557 to rats after reversal of all toxic signs from the first administration induced the same symptoms and degree of toxicity as the initial injection. Reversible myelosuppression was the predominant feature of toxicity in mice and rats, but at equimolar doses this myelotoxicity was less than half that of cyclophosphamide (CP). First signs of immunosuppression were seen only at 100 mg/kg i.v.. No severe urotoxicity was observed in rats with single i.v. doses up to 192 mg/kg. This might be due to the fast and complete renal excretion of the thiol moiety of Z 7557, whereas the activated oxazaphosphorine component occurred in the urine only to a much smaller amount, as could be shown by a pilot pharmacokinetic study. In conclusion, Z 7557 appeared to have an overall tolerance in rats and mice similar to cyclophosphamide but was clearly less toxic with respect to the bone marrow, the immune system and the urinary tract.

Animals↗

[Morphometrically definable aging velocities of cells and tissues].

We determined aging changes of the nucleus-cytoplasm-relation in the epithel of the human epiglottis and intestine of rats. The results were compared with data about the proliferation of connective tissue and the decrease of muscle cells in the wall of the intestine and in the ciliary muscle. We adapted exponential functions to the measured results. For comparing the several equations and the derivable aging velocities, the nucleus-cytoplasm-relation must be transformed into nucleus volume rate of the total cell volume. Similarities in the decrease of the aging speed in the course of life and in the value of the exponent of the aging function by W. Beier (approximately 0,03) were demonstrated.

Aging↗

Electron microscopic characterization of intermediate filaments in rat liver parenchymal cells.

Filamentous networks were isolated from rat liver and studied by electron microscopy after negative staining with uranyl acetate. Highly purified preparations of networks were used to obtain material for immunological studies, but morphological studies were made more satisfactorily on preparations purified only by sucrose density gradient centrifugation. The filaments forming the networks were 7 to 11 nm thick, consistent with classification as intermediate filaments. On immunofluorescence microscopy using antibodies directed against filament-forming proteins, both the networks in the isolated preparations and the filamentous networks in cryosections were visualized, thus providing evidence that the network isolated from rat liver homogenate corresponds to the network in intact parenchymal cells.

Animals↗

Visualization of a filamentous network in cryo sections of liver tissue.

In cryo sections of rat liver, briefly fixed with 0.1% or 0.2% glutardialdehyde, a filamentous network could be demonstrated by electron microscopy. A filamentous network of similar shape was found in a fraction prepared from rat liver homogenate. The presence of similar structures in two different preparations from the same tissue suggests that they represent an equivalent structure in the living cell.

Animals↗