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Biomedical subjects

M Siess

Publications and source records attributed to M Siess.

At least 37 records · Page 2Linked to original sources
PubMed2001

[Organizational prerequisites for multimodality therapy concepts].

The increasing use of multimodal therapies confronts clinics with the need to create new organisational structures. The high degree of specialisation necessitates that the separate disciplines seek ways of working closer together. This is particularly the case when staging results have to be evaluated and a multimodal therapy course chosen or when quality management issues and the coordination of different steps of a treatment are being considered. By establishing disease-oriented organisational structures and by institutionalizing interdisciplinary cooperation, e.g. in daily tumor board meetings and in fixed disease management teams, the organisational prerequisites for implementing multimodal therapies are created.

Combined Modality Therapy↗
PubMed2001

[DRGs in surgery from the viewpoint of a clinic].

Because of the significance that documentation has in order for the first DRG budget to be drafted in 2003, priority has to be given in all surgical departments to assuring that codification is of a very high standard. Clinical management and senior surgeons will have to develop strategies which enable them to maintain patient care, a range of services, and efficiency in their surgical departments. Defining and concentrating on core competences and the value chain in surgery will be of increasing importance in their ability to assert themselves in future. The introduction of the DRG system will give new value to the surgeon's role in modern departments and in clinical management.

Diagnosis-Related Groups↗
PubMed2000

[Consultation and liaison activity from the socioeconomic perspective. A plea for cost-benefit analysis in psychosomatics].

Within the last decade cost-effectiveness assumes a much more strategic perspective in the rationing of care that is taking place due to evidently increasingly limited financial resources and managed-care driven protocols. As universities and general hospitals face this increasing pressure to justify services within their facilities, consultation-liaison (C/L) programs need to carefully address and evaluate the financial base of the services they provide. Overlooking or neglecting the financial aspects of C/L-services has already resulted in the closure or service reduction of C/L-programs throughout the United States. Whereas a result of that development interest in cost-effectiveness research is considerable in the US and GB and has produced some good evidence for the impact of psychosocial problems on the outcome and cost of medical care, nearly no such studies come from the German-speaking countries. The present article reviews the worldwide existing literature concerning cost-effectiveness analyses of C/L-work and attempts to guide the reader through the currently available methods for cost-effectiveness research. As a conclusion we propose somatisation syndromes as one patient group. There the development of appropriate treatment regiments is vital both concerning clinical and socioeconomical aspects.

Cost-Benefit Analysis↗
PubMed1991

Work and contraction curves of atrial muscle preparations during anoxia and reoxygenation influenced by cardio-tonic and cardio-depressive drugs.

Auxotonic work/beat and contraction curves were recorded from left guinea pig atria stimulated with 0.5 Hz at 5 mN preload in K.H.-solution + 15 mmol/l glucose, 95% O2 or N2 + 5% CO2, 30 degrees C. Eight common parameters of the contraction curve were calculated simultaneously in a computerized system as reported previously (Englert, R. et al., N.-Arch. of Pharmacol., 337, Suppl. R. 60, 1988). By increased anaerobic glycolysis anoxia reduced contractile activity which after 30 min reached a plateau of approximately 50% of the initial aerobic value during approximately 2 hours. At reoxygenation the contraction force increased with a first peak overshooting 50% of the initial aerobic value after 5-10 min, to decline during the following 10-15 min to a plateau slightly below the initial aerobic value. Several parameters exhibited characteristic changes during anoxia and reoxygenation: during the first minutes of reoxygenation in the ascension of the first peak the 'time to peak force', the 'relaxation time' and the 'area under the contraction curve', especially the part below the relaxation, were strongly but only transiently increased. Positive and negative inotropic agents influencing cytosolic free Ca2+ in different ways applied 15 minutes before reoxygenation indicated that the observed overshooting peak of force and the prolongation of contracation duration after reoxygenation were presumably due to transiently disturbed intracellular Ca2+ redistribution in sarcoplasmic reticulum and mitochondria during the restitution of high energy phosphates.

Adaptation, Physiological↗
PubMed1987

Differential inotropic and chronotropic effects of various protein kinase C activators on isolated guinea pig atria.

1,2-Dioctanoylglycerol (10-100 microM) produced a positive inotropic effect on electrically stimulated left guinea pig atria and increased the frequency of spontaneously beating atria. Various phorbol esters and mezerein induced heterogeneous responses of the left atria. Phorbol dibutyrate and phorbol didecanoate decreased the force of contraction to different extents, whereas phorbol myristate acetate and mezerein had dual actions: an initial enhancement followed by a decline in force. None of these compounds changed the spontaneous atrial rate.

Animals↗
PubMed1987

Cardiac energetics: significance of mitochondria.

The mitochondrial activity as the energy producing step during biological oxidation was observed at rest and its regulation by the energy consuming auxotonic contractile work, depending on the preload, afterload and beat rate in isolated superfused left guinea pig atria. The mitochondrial activity was measured by (1) continuous determination of the O2 uptake rate, (2) the rate of 14CO2 production from labelled glucose or FFA and (3) separate measurements of the atrial ATP-, ADP-, AMP-, CP- and NAD-concentrations, for determination of the energy state. Some results, with points of general interest, are reported and discussed, including this model, former studies about cardiac energetics and the efficiency of cardiac work, reviewed recently.

Animals↗
PubMed1986

Some problems of cardiac energetics.

Special problems of the aerobic metabolism in the cardiac muscle cell as an energy producing and energy consuming system are discussed and demonstrated with some experimental results using superfused resting and working guinea-pig atria as an energetic model: 1. Influence on resting O2 uptake: a) Free fatty acids (FFA) increase the O2 uptake rate to approximately 20% compared with glucose oxidation. This can be explained as a compensating effect due to the 9.7% lower combustion value for 1 mol O2 of C16-FFA and the 10.7% lower P/O-ratio related to glucose oxidation. b) K+-depolarization increases the O2 uptake b.1. between 15 and 65 mmol/l KCl from 110 to 200% without activation of the actomyosin system. This effect is Ca++ dependent and is not observed in Ca++ free solution and can be inhibited completely by nifedipine. The enhanced O2 uptake rate due to K+-depolarization is not connected with an improved state of the energy quotient (ATP/ADP+AMP) indicating a lowering of the energy coupling. b.2. between 100 and 250 mmol/l KCl from 220 to approximately 350%, not influenced by nifedipine and connected with activation of the actomyosin system at low Na+ and/or high external Ca++ (contracture). 2. Stretching of resting atria up to 10 mN tension does not increase the O2 uptake rate. The 'Feng' effect could not be confirmed. 3. a) The 'Frank-Starling' effect can be observed between 2.5 and 10 mN preload with increase of contractile work/beat connected with an enhancement of O2 uptake rate to a lower percentage. At the maximum of the 'Frank-Starling' effect the highest efficiency of contractile work can be observed. With increasing beat rate this maximum is shifted to a lower preload. b) The auxotonic contractile work measured by a calibrated spring blade allows the calculation of the 'internal work' and the 'external contractile work'/beat in mm X mN. The total energy of the activated actomyosin system (total work) is stored by the displacement of the spring blade due to the constant of the spring blade, the preload (tension) and the afterload (force). The 'internal work' will be transformed into ATP dependent heat and force equal to the preload tension. The same ATP dependent energy from O2 uptake is transformed at the same beat rate and the same preload a) with the isometric type of auxotonic contraction into high force and very low internal and low external work.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1981

[The effect of AR-L 115 BS on the function and oxygen consumption of isolated guinea pig atria as compared to g-strophanthin and theophylline].

Dose-response curves with ouabain, theophylline and 2-[(2-methoxy-4- methylsulfinyl)phenyl] -1H-imidazo[4,5-b]pyridine (AR-L 115 BS) were obtained from electrically driven isolated left guinea pig atria (at 35 degrees C and 3 Hz, 0.5 ms and 0.4--0.6 mA 10% above threshold) measuring the auxotonic contraction work beat. The dose-response curve of the inotropy and frequency was very similar in shape to that of theophylline as far as intensity of inotropy and the range of dosage is concerned, but AR-L 115 BS is 10 times as active. The maximum of the increase of frequency was less under AR-L 115 BS than under theophylline. Also the toxicities of the two substances are very similar with a concomitant decline of inotropism. Both substances are clearly distinct from ouabain. As to the economic effect, however, AR-L 115 BS shows, in submaximally effective concentrations, similarity to the economic type of ouabain whereas, at the maximum of contractile activity, the efficiency is lowered as was observed with theophylline. In the "anoxia test" the anoxic tolerance was shortened by AR-L 115 BS similar to theophylline when the anoxic contractile activity was stimulated below the maximum level in contrast to the prolongation due to ouabain.

Animals↗
PubMed1980

Anoxic energy production and contractile activity in mammalian cardiac muscle.

Contractile activity of electrically driven left atria of guinea pigs was measured auxotonically under normoxic and anoxic conditions at various frequencies and temperatures in Krebs-Henseleit solution containing 15 mM glucose. At 35 degrees C, a frequency of 0.5 Hz and anoxia ("anoxia test") reduced contractile activity was observed, lasting 6.6 +/- 1.55 hr. Under normoxic conditions at 0.5 Hz and 35 degrees C the contractile work per beat (cwb) amounts to 35% of the maximum reached at 1.5 Hz, according to the force-frequency relationship. The total contractile work per hr only comes up to 5% of the maximum reached at 4.0 Hz. The oxygen consumption at 0.5 Hz only exceeds the value of resting atria by 10%. A positive inotropic peak of short duration observed directly after acute anoxia can be antagonized by beta-receptor blockade. Then contractile activity decreases during the first half hr of anoxia to around 20%-30% of the initial value under oxygen. In the second phase, the reduced contractile activity recovers and is stabilized at a level between 50%-80% of the control value during the first and second hour of anoxia and then decreases slowly during the following hours. The recovery period of anoxic contractile activity coincides with the time-dependent increase of the lactic acid production rate which reaches a maximum after around 1 hr of anoxia. This can also explain why the rapid decrease of ATP (30%) and creatine phosphate (CP) (90%) during the first 20 min is stabilized at this reduced value during the 2 hr of anoxia studied. Related to the measured oxygen consumption during normoxia, the glucose consumption increases during anoxia in resting atria approximately 300% and, in beating atria, approximately 650%, representing an ATP production rate of approximately 20% and approximately 50%, respectively, related to aerobic conditions. G-strophanthin enhances anoxic contractile activity up to 200% of the aerobic initial control value and prolongs the anoxic tolerance from 6.6 +/- 1.55 to 21.2 +/- 3.3 hr without significant additional increase of glycolysis or a further decrease of energy-rich phosphates. Addition of adenine and ribose as precursors of the adenine nucleotide pool during the first and second hours of anoxia increases anoxic contractile activity and avoids loss of ATP, ADP, and CP, without enhancemnt of glycolysis. The importance of these findings for anoxic survival of cardiac tissue is discussed. This "anoxia test" can be used to check influence on: 1) force and duration of anoxic contractile activity as well as anoxic arrhythmias (anoxic energy consumption), 2) the rate of anaerobic glycolysis (anoxic energy production), and 3) the concentration of energy-rich phosphates (energy storage).

Animals↗
PubMed1977

The effects of arachidonic acid in isolated atria of guinea pigs.

The effects of free and albumin-bound arachidonic acid, which is the precursor of the prostaglandins E2 and F2alpha, were studied on the spontaneous rate, contractile force and myocardial fatty acid metabolism in isolated, spontaneously beating atria of guinea pigs. Both free and albumin-bound arachidonic acid (10(-6)-10(-3) M) produced a dose-dependent positive chronotropic and a modest inotropic action. Tachyphylaxis to the positive chronotropic action of arachidonic acid developed in the course of repeated applications. Beta-Adrenoceptor blockade (pincolol) and pretreatment with reserpine or prostaglandin-synthetase inhibitors (indomethacin, fenoprofen, aspirin, 5,8,11,14-eicosatetraynoic acid) failed to affect the chronotropic activity of arachidonic acid significantly. The action of arachidonic acid was independent of the decarboxylation of the fatty acid. Linoleic and oleic acids did not show any positive chronotropic activity. The data are interpreted as suggesting that changes induced by arachidonic acid might be partly due to peroxides formed from arachidonic acid.

Animals↗
PubMed1975

Effect of histamine H2-receptor and beta-receptor blockade on histamine-, orciprenaline- and prostaglandin-stimulated frequency of the isolated guinea-pig atrium.

For the oxyntic cell of the stomach the hypothesis was forwarded by Grossmann and Konturek [1] that, if one of its three receptors is blocked, the physico-chemical properties of the two others are changed in such a way that they respond less sensitively to their specific stimulation. This hypothesis was tested for the heart by studying the effect of histamine-H2-receptor- and beta-receptor-blockade on the orciprenaline-, histamine-, and prostaglandin E1-stimulated frequency of the spontaneously beating isolated guinea-pig atrium. Therefore cumulative dose response curves were established for orciprenaline, histamine and prostaglandin E1 (PGE1) alone or in the presence of metiamide or pindolol. (1) The beta-blocker pindolol inhibited the effect of orciprenaline in a competitive manner, without having an effect on histamine- and PGE1-stimulation. (2) The histamine H2-receptor blocker metiamide inhibited the histamine response competitively. (3) In contrast to pindolol, metiamide inhibited the PGE1-stimulated rise in atrial frequency, most obviously non- or uncompetitively. From these results it is evident that in the heart the particular inhibitors, at least at the receptor site, act rather specifically without affecting neighbouring receptors and that metiamide influences the PGE1-response in a way different from the receptor site.

Animals↗