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H Lill

Publications and source records attributed to H Lill.

88 records · Page 5Linked to original sources
PubMed1987

[Biochemical and physiologic principles of tissue-type plasminogen activator].

After wound healing the protective fibrin clot is removed by the fibrinolytic system. In addition fibrinolysis is one of the most important counter-reactions of blood coagulation. Fibrinolysis is controlled by activation and inhibition processes. Tissue type plasminogen activator (t-PA) and Pro-urokinase (single chain urokinase; scu-PA) hold a key position in physiological plasminogen activation. Plasmin itself is a rather unspecific protease capable of degrading a great variety of proteins besides fibrin. In vivo however--except for certain pathological situations--the fibrinolytic process is restricted to its actual target the fibrin clot. This surprising situation in terms of structure function interrelation is physiologically managed by N-terminal modules in the protein structure of the essential factors providing fibrin affinity. Free plasmin will be immediately inactivated by alpha 2-antiplasmin. Therefore fibrin plays a central role as cofactor in the fibrinolytic system in determining initiation and localization of the fibrinolytic process. Because of the superior properties of t-PA and scu-PA with respect to fibrin specificity both activators must be regarded as the future thrombolytic agents for therapy.

Fibrinolysis↗
PubMed1986

The proton channel, CF0, in thylakoid membranes. Only a low proportion of CF1-lacking CF0 is active with a high unit conductance (169 fS).

We investigated the conductance of pea thylakoid membranes and their capacity for photophosphorylation as function of the extraction of chloroplast coupling factor CF1. The degree of extraction was varied via the incubation time in EDTA-containing hypo-osmolar medium and was measured by rocket electroimmunodiffusion. The conductance of thylakoid membranes was measured by flash kinetic spectrophotometry. The time course of extraction followed the time course of thylakoid swelling. Contrary to expectation increasing loss of CF1 did not primarily increase the velocity of proton efflux from each vesicle. Instead proton-tight vesicles were converted to leaky ones, which lost phosphorylating activity. Two subpopulations occurred, although both types of vesicles, leaky and proton-tight ones, were CF1-depleted to a similar degree. This implied that only a small fraction of CF1-lacking CF0 was functional as a proton channel. Tight vesicles had no functional channels while leaky ones had at least one. We determined the proportion of tight vesicles in three independent ways: via the residual phosphorylation activity, via measurements of proton efflux and via measurements of the electric relaxation across the membrane. The results obtained were identical. A statistical evaluation of the data led us to the following conclusions. EDTA treatment produced vesicles containing approximately 10(5) chlorophyll molecules, equivalent to a total of approximately 100 CF0CF1 per vesicle. Even at the highest degree of extraction (75% of total CF1 extracted) only 2.5 out of 75 exposed CF0 per vesicle were proton-conducting. The unit conductance of one open CF0 channel was 169 +/- 18 fS at pH 7.5 and room temperature. At an electrical driving force of 100 mV this was equivalent to the passage of approximately 10(5) protons/s. The most important consequence of this relatively high unit conductance was that a single open CF0 channel was capable of dissipating the protonmotive force of one vesicle, thereby deactivating the whole remaining catalytic capacity of this vesicle.

Edetic Acid↗
PubMed1986

Reconstitution of CF1-depleted thylakoid membranes with complete and fragmented chloroplast ATPase. The role of the delta subunit for proton conduction through CF0.

Chloroplast ATPase (CF1) was isolated from spinach, pea and maize thylakoids by EDTA extraction followed by anion-exchange chromatography. CF1 was purified and resolved by HPLC into integral CF1, and CF1 lacking the delta & epsilon subunits: CF1(-delta) and CF1(-epsilon). Washing Mono-Q-bound CF1 with alcohol-containing buffers followed by elution without alcohol produced the beta subunit and in separate peaks CF1(-delta) and CF1(-epsilon). Elution from Mono Q in the presence of tenside yielded a beta delta fragment, CF1(-delta) and CF1(-delta epsilon). Chloroplasts were CF1-depleted by EDTA extraction. Reconstitution of photophosphorylation in these 'EDTA vesicles' was obtained by addition of CF1 and its fragments. CF1, CF1(-delta) and CF1(-delta epsilon) were active with cross-reactivity between spinach, pea and maize. delta-containing CF1 always reconstituted higher activities than delta-deficient CF1. The beta delta fragment and dicyclohexylcarbodiimide (DCCD)-inhibited CF1 also were reconstitutively active while beta and DCCD-inhibited CF1(-delta) were not. These results support the notion that subunit delta can function as a stopcock to the CF0 proton channel as proposed by Junge, W., Hong, Y. Q., Qian, L. P. and Viale, A. [(1984) Proc. Natl Acad. Sci. USA 81, 3078-3082].

Chloroplasts↗
PubMed1985

Development of a photometric assay for activated partial thromboplastin time and its application to the Cobas Bio centrifugal analyzer.

We describe a two-step procedure for APTT that can be performed on photometric devices. It includes preincubation of diluted plasma with ellagic acid and phospholipids and a starting reagent that contains calcium and a chromogenic peptide substrate for thrombin, Tos-Gly-Pro-Arg-pNA. Reaction time is recorded from addition of the starting reagent until thrombin formation occurs, and a prefixed amount of substrate is cleaved. The pattern of sensitivity to clotting factors and heparin was similar to clotting assays and the substrate used did not interfere with the activity of factor Xa. An application of the method was made for the Cobas(R) Bio centrifugal analyzer. Absorbance readings were sent to an external computer and were transformed into reaction times by a computer program. Although the results are independent on fibrinogen concentrations, from kinetic data of the reaction curve fibrinogen concentrations can be estimated. Correlation studies showed good correspondence to clotting methods (r = 0.92, n = 53) as well as an excellent precision (CV 3% for inter-assays, n = 15) and high throughput of samples (greater than 100/h) in the automated assay.

Apoproteins↗
PubMed1980

Determination of the biological activity of heparin by use of a chromogenic substrate.

We describe a new method for determining the biological activity of heparin in plasma with use of thrombin and the substrate Tos-Gly-Pro-Arg-pNA. The procedure is based on the photometric determination of the inactivation of thrombin after incubation with plasma in the presence of endogenous antithrombin III (At III). The method allows the specific determination of heparin concentrations from 0.02 USP to 0.8 USP/ml of plasma in the presence of normal At III levels. It has been carried out manually by use of an Eppendorf spectrum line photometer or automatically by use of a Vitatron Akes analyzer. For evaluation, the results were compared with two standard samples which contained heparin in the low and high therapeutic range, respectively.

Anilides↗
PubMedDate not supplied

[Isolated rupture of the subscapularis tendon in the overhead athlete - the result of chronical overuse?].

The case of a 27-year-old overhead athlete with chronic shoulder pain because of an isolated subscapularis tear without trauma is described. Arthroscopy has proven to be the appropriate method for detailed visualisation of the injury and facilitates the operative planning. Furthermore, arthroscopy closes the problem of a "diagnostic gap". In the presented case, the results at the two year follow-up are excellent. The authors conclude that an operative approach is also justified in non-traumatic isolated ruptures of the subscapularis muscle.

Adult↗