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Biomedical subjects

K Werdan

Publications and source records attributed to K Werdan.

At least 199 records · Page 11Linked to original sources
PubMed1978

[Study of combined injuries (23rd communication) (author's transl)].

NMRI-mice which were whole-body irradiated, received two or three days later open skin wounds. While irradiation or wounding alone caused a mortality of 10 to 20% and 0% respectively, a combination of injuries caused 80 to 100% mortality. With regard to the as yet unexplained pathogenesis of this clinical condition, bacteriological examination of the skin-wound was undertaken. Staphylococci, lactobacilli and gramnegative bacilli were found on the wounds, and the bacterial concentration per cm2 wound area among animals with combined injuries was significantly higher than in controls. Covering the wounds with lint effected a distinct reduction of bacterial number as well as a reduction of mortality. A similar success of therapy was attained through local administration of antibiotics. A possible correlation between bacterial seeding and increased mortality is discussed.

Administration, Topical↗
PubMed1975

The role of pH in the regulation of carbon fixation in the chloroplast stroma. Studies on CO2 fixation in the light and dark.

1. The pH in the stroma and in the thylakoid space has been measured in a number of chloroplast preparations in the dark and in the light at 20 degrees C. Illumination causes a decrease of the pH in the thylakoid space by 1.5 and an increase of the pH in the stroma by almost 1 pH unit. 2. CO2 fixation is shown to be strongly dependent on the pH in the stroma. The pH optimum was 8.1, with almost zero activity below pH 7.3.Phosphoglycerate reduction, which is a partial reaction of CO2 fixation, shows very little pH dependency. 3. Low concentrations of the uncoupler m-chlorocarbonylcyanide phenylhydrazone (CCCP) inhibit CO2 fixation without affecting phosphoglycerate reduction. This inhibition of CO2 fixation appears to be caused by reversal of light induced alkalisation in the stroma by CCCP. 4. Methylamine has a very different effect compared to CCCP. Increasing concentrations of methylamine inhibit CO2 fixation and phosphoglycerate reduction to the same extent. The light induced alkalisation of the stroma appears not to be significantly inhibited by methylamine, but the protons in the thylakoid space are neutralized. The inhibition of CO2 fixation by higher concentrations of methylamine is explained by an inhibition of photophosphorylation. It appears that methylamine does not abolish proton transport. 5. It is shown that intact chloroplasts are able to fix CO2 in the dark, yielding 3-phosphoglycerate. This requires the addition of dihydroxyacetone phosphate as precursor of ribulosemonophosphate and also to supply ATP, and the addition of oxaloacetate for reoxidation of the NADPH in the stroma. 6. Dark CO2 fixation in the presence of dihydroxyacetone phosphate and oxaloacetate has the same pH dependency as CO2 fixation in the light. This demonstrates that CO2 fixation in the dark is not possible, unless the pH in the medium is artificially raised to pH 8.8.

Adenosine Triphosphate↗
PubMedDate not supplied

Application of high resolution two-dimensional polyacrylamide gel electrophoresis of polypeptides from cultured neonatal rat cardiomyocytes: regulation of protein synthesis by catecholamines.

High resolution two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) was applied to cultured neonatal rat heart muscle cells, incubated for 72 h at 37 degrees C in serum-free medium, either in the absence or in the presence of 0.1 microM norepinephrine. After silver staining, about 340 and 550 protein spots could be seen in cardiomyocytes, cultured either in the absence or presence of norepinephrine. Of these spots, 141 could be further characterized according to isoelectric point and molecular weight, with 71 protein spots being present under both conditions. In cells cultivated in presence of norepinephrine, 58 new protein spots appeared, whereas 12 spots disappeared, and 22 spots increased (whereas 3 spots decreased) in intensity. In comparison with 2-D PAGE of rat cardiomyocytes, the protein pattern of the intact heart of neonatal rats is incongruent. 2-D PAGE of polypeptides of cultured neonatal rat cardiomyocytes may be a suitable tool to study the regulation of protein synthesis by various stimuli with relevance to cardiac growth adaptation, inotropy and heart failure.

Animals↗
PubMedDate not supplied

Regulation of protein biosynthesis in neonatal rat cardiomyocytes by adrenoceptor-stimulation: investigations with high resolution two-dimensional polyacrylamide gel electrophoresis.

The role of alpha- and beta-adrenoceptor-mediated regulation of protein patterns in cultured neonatal rat cardiomyocytes was studied with high resolution two-dimensional polyacrylamide gel electrophoresis. Spontaneously beating neonatal rat cardiomyocytes were cultured for 72 h at 37 degrees C in serum-free medium, supplemented with either the catecholamine norepinephrine (0.1 microM), or with norepinephrine (0.1 microM) plus the alpha 1-adrenoceptor blocker prazosin (1 microM), or with neither of these substances. In transmission light, 105 protein spots could be seen in the lysates from control cells, 244 spots were identified in lysates from norepinephrine-treated cells, and 114 protein species were counted in the case of lysates from cardiomyocytes which had been cultured in the presence of norepinephrine plus prazosin. This experimental approach allows a clear classification of alpha- and non-alpha (probably beta)-adrenoceptor-mediated catecholamine effects on protein synthesis in cardiomyocytes. In comparison with previous experiments (Chang et al., Electrophoresis, this issue, pp. 748-754), less protein species were identified in the untreated control cardiomyocytes, as well as in the norepinephrine treated cells. The only actual modification in the experimental setup in these two series was the addition of dimethyl sulfoxide--a substance known for its repressive effect on oncoprotein expression--to the culture medium, as solvent for prazosin.

Animals↗
PubMedDate not supplied

Noradrenaline-induced desensitization in cultured heart cells as a model for the defects of the adenylate cyclase system in severe heart failure.

Cultivation of rat heart muscle cells for up to 5 days in the presence of 10(-6) mol/l (-)noradrenaline leads to a desensitization of the cells to inotropic stimulation and cAMP formation at different levels of the cAMP-system: The decrease in the responsiveness to the beta-adrenoceptor agonist isoprenaline quantitatively parallels the down-regulation of beta 1-adrenoceptors. The impairment of the positive inotropic effect of the phosphodiesterase-inhibitor IBMX is associated with a diminished basal cAMP-formation but an unchanged phosphodiesterase-activity in noradrenaline-treated cells. This decrease in basal cAMP-accumulation as well as the attenuation of the forskolin-stimulated cAMP-formation indicate that a defect in the adenylate cyclase system beyond the receptor must be involved in noradrenaline-induced desensitization. In contrast to the diminished effectiveness of cAMP-increasing agents the positive inotropic effect of ouabain and the alpha-adrenoceptor-mediated positive inotropic effect of phenylephrine are unaltered in noradrenaline-treated cells. It is concluded from these results that in addition to the down-regulation of beta 1-adrenoceptors a defect on the post-receptor level of adenylate cyclase occurs in noradrenaline-induced desensitization not affecting mechanisms beyond the catalytic subunit of adenylate cyclase. As these findings are very similar to those observed in isolated preparations from severely failing human hearts, the presumption is confirmed that noradrenaline-induced desensitization might constitute an important etiological factor in the subsensitivity of failing human hearts to inotropic stimulation.

1-Methyl-3-isobutylxanthine↗
PubMedDate not supplied

Xenoreactive natural antibodies and induced antibodies--their effects of beating cardiomyocytes as a model of a xenograft.

Xenotransplantation has been complicated by hyperacute rejection reactions, which are supposedly triggered by preformed natural antibodies (PNAb) of the recipient organism, whereas the role of antibodies specifically induced by previous antigen contact (IAb) is less clear. Primary cultures of spontaneously beating neonatal rat cardiomyocytes were used as a model of the heart to elaborate the effects of both PNAb and IAb from xenogeneic species and to investigate into their mechanisms of action. An experimental setup allowing for rapid medium exchange under continuous observation was employed. Sera containing PNAb reproducibly bring about a stereotype pattern of altered contractility including an initial increase in beating frequency followed by a temporary cessation of beating within the first minutes after administration. After recovery of spontaneous contractions, the cells within the monolayer exhibited a dissociation of the synchronicity of the beating persisting for several hours. The temporary pause in beating was prevented by a very high extracellular calcium concentration, but not by extracellular electrical stimulation sufficient to trigger contractions in control cells. Electrophysiological measurements carried out in adult ventricular guinea pig heart muscle cells under the same experimental conditions revealed an increase of the excitation threshold of the cells after application of sera containing PNAb due to an enhanced input resistance. These results indicate that the effect of PNAb is the consequence rather of a generally reduced excitability of the cell than of the inhibition of a singular ionic conductance. After specific absorption of PNAb directed against rat antigens beating of neonatal rate cardiomyocytes ensued without interruption. Sera specimens devoid of complement produced similar effects on contractility, although the duration of the standstill period was significantly shorter. The increase in input resistance visualized in guinea pig myocytes was absent after removing PNAb against guinea pig antigens but not after absorbing PNAb directed against rat epitopes. Signs of a permanent cytotoxicity after the administration of PNAb were lacking in all experiments. IAb against rat heart tissue raised in rabbits stopped the contractions of neonatal rat cardiomyocytes within 30 min after administration irreversibly and lead concentration-dependently to a destruction of the cells.

Animals↗
PubMedDate not supplied

Elucidating molecular mechanisms of septic cardiomyopathy--the cardiomyocyte model.

In the multiple organ dysfunction syndrome of sepsis and septic shock the heart is one of the organs subject to failure. Many new insights into the mechanisms underlying septic cardiomyopathy were gained in the last years. Experimental work with neonatal and adult cardiomyocytes considerably contributed to this progress, facilitating the documentation of direct attenuation of the contractions of the heart muscle cell by toxins and mediators, as well as investigating the underlying cellular mechanisms. With this respect, contractile-depressant effects have been found in cardiomyocytes for many toxins and sepsis mediators, with endotoxin, Pseudomonas exotoxin A, tumor necrosis factor alpha, interleukin-1 and nitric oxide being the most relevant ones identified. These substances interfere at clinically relevant concentrations with several main inotropic axes, not only with the beta-adrenoceptor/adenylyl cyclase and with the NO-cGMP-system-on which most of the interest is focused at present-but also with the alpha 1-adrenoceptor/phosphoinositide pathway and the Ca2+ homeostasis of the cardiomyocyte, the latter representing the common final inotropic pathway. Not a single cardiodepressant factor, but more likely a total bunch of toxins and mediators with different attack mechanisms seem to contribute to the picture of septic cardiomyopathy.

ADP Ribose Transferases↗
PubMedDate not supplied

Supplemental immunoglobulin (ivIgG) treatment in 163 patients with sepsis and septic shock--an observational study as a prerequisite for placebo-controlled clinical trials.

In a multicenter observational study of 163 medical and surgical patients with a total of 173 episodes of sepsis or septic shock (Elebute sepsis score: 19.0 +/- 0.5), the effects of supplemental i.v. immunoglobulin (i.v. IG) treatment (unmodified polyvalent IgG pH 4.25, n = 123; for Pseudomonas sepsis, n = 50, Pseudomonas IgG) on multiple organ failure (MOF) were investigated by means of APACHE II score changes (pretreatment: 23.7 +/- 0.6). In 44% of the cases ("responders"), a prompt improvement in APACHE II score (defined as decrease greater than or equal to 4) was evident from day 0 to day 4 after onset of therapy, thus being in close time relationship to the i.v. IG administration. This improvement, associated with a better prognosis (mortality 24% vs. 55%), was found in all subgroups, most importantly the following: polyvalent IgG vs. Pseudomonas IgG treatment; medical vs. surgical patients; moderate vs. severe MOF; and gram-positive vs. gram-negative septicemia. In a small-sized second comparative nonrandomized control group (n = 27, antibiotic treatment alone) of septic patients (Elebute: 14.7 +/- 1.0) with similar MOF severity (APACHE II: 23.6 +/- 1.4), the response rate (30%) was, though not statistically significant, lower by one-third. The optimal baseline score ranges for patient inclusion into future placebo-controlled randomized i.v. IG trials were found to be 20-35 for the APACHE II score and 12-27 for the Elebute score.

Adult↗
PubMedDate not supplied

Peripheral oxygen availability within skeletal muscle in sepsis and septic shock: comparison to limited infection and cardiogenic shock.

In 40 intensive care patients, tissue oxygen partial pressure distribution within skeletal muscle was measured in order to estimate peripheral oxygen availability. In septic patients with multiple organ failure (n = 20) mean skeletal muscle pO2 was abnormally high (48.8 +/- 8.5 mmHg, p less than 0.001) in contrast to patients with limited infection without sepsis (28.3 +/- 5.9 mmHg, n = 10). Mean muscle pO2 also discriminated between septic and cardiogenic shock (22.6 +/- 6.9 mmHg, p less than 0.001). The characteristic pattern of oxygen availability in septic patients--but not in patients with limited infection--was high skeletal muscle pO2 high whole body oxygen delivery and low whole body oxygen extraction, which was not influenced by the type of pathogenic agent of sepsis. In our patients in severe stage of sepsis, we did not observe local skeletal muscle hypoxia due to microcirculatory disorder. High mean skeletal muscle pO2 suggested reduced oxygen consumption within tissue rather than reduced oxygen transport to tissue in sepsis.

Bacterial Infections↗
PubMedDate not supplied

Cardiovascular parameters and scoring systems in the evaluation of response to therapy in sepsis and septic shock.

In 47 medical and postoperative ICU patients with 57 episodes of sepsis and septic shock, cardiovascular parameters including systemic vascular resistance (SVR), cardiac index (CI), stroke volume index (SVI), left ventricular stroke work index (LVSWI) as well as six scoring systems (APACHE II, Elebute, Goris, HIS, SAPS and SSS) were studied regarding their usefulness in the assessment of disease progression and evaluation of response to supplemental sepsis therapy (immunoglobulins, plasmapheresis). Among the hemodynamic parameters, only a prompt SVR improvement significantly discriminated between ultimate survivors and nonsurvivors. Thus, an increase in SVR (greater than 160 dyn*cm-5*sec, within days 0 to 4, persisting for greater than 24 hours) can serve as a prognostically validated "response" criterion (responders/non-responders: 26/31; mortality: 27% vs. 77%). Non-invasively, the APACHE II score was best suited (specificity: 88%, sensitivity: 67%) to classify hemodynamically defined responders to supplemental sepsis treatment (score-reduction greater than or equal to 4 on day 4 after onset of therapy).

Adult↗
PubMedDate not supplied

Severity of multiple organ failure (MOF) but not of sepsis correlates with irreversible platelet degranulation.

Multiple hemostatic changes occur in sepsis and multiple organ failure (MOF). To evaluate the role of platelets in patients with sepsis and MOF, we examined changes in surface glycoproteins on circulating platelets of 14 patients with suspected sepsis and MOF. The severity of sepsis and MOF was assessed by the Elebute and APACHE II scoring systems, respectively. Using flow cytometric techniques and platelet specific monoclonal antibodies, platelet surface expression of fibrinogen receptor on GPIIb-IIIa, of von Willebrand Factor receptor GPIb, and of granule glycoproteins (thrombospondin (TSP), GMP-140, GP53) was measured. Plasma membrane expression of GPIIb-IIIa and GPIb on circulating platelets was not affected by sepsis of MOF. Septic patients, however, showed a significantly elevated fibrinogen receptor activity (LIBS1 expression) (p < 0.05) that correlated with severity of disease (r = 0.597, p = 0.043). No significant change in surface expression of granule glycoproteins (TSP, GMP-140, GP53) was noted in septic patients. In contrast, degranulation of granule glycoproteins was significantly elevated in MOF (p < 0.05) which well with severity of MOF (GMP-140, r = 0.611, p = 0.013; TSP, r = 0.643, p = 0.026). We speculate that platelets in sepsis circulate in a hyperaggregable but still reversible state that results in increased risk of microthrombotic events. In the course of the disease, irreversible platelet degranulation of adhesion molecules occurs that may play an important role in the development of MOF.

Adolescent↗
PubMedDate not supplied

Evaluation of definitions and parameters for sepsis assessment in patients after cardiac surgery.

In 110 patients undergoing elective heart surgery on extracorporeal circulation, various parameters were studied regarding the early assessment of septic complications. In a first step, the Elebute score definition for postoperative sepsis validated in general surgery patients (score > or = 12) could be confirmed in an extended form (> or = 12 on > or = 2 days) for cardiac surgery patients. According to this definition (overall classification accuracy for clinically defined sepsis-related mortality: 94%), septic complications occurred in 16 patients and were associated with a significantly worse prognosis than in non-septic patients (mortality 69% vs. 1%, p < 0.0001). In contrast, SIRS (best classification criterion: positive on > or = 3 days) displayed a lower specificity for clinically defined sepsis-related mortality, at least during the early postoperative course (accuracy: 67%). Based on the Elebute score classification, other more practicable parameters were investigated regarding their usefulness for an early sepsis risk assessment in post cardiac surgical patients. Five additional severity scores (APACHE II, MOF-Goris, HIS, SAPS, SSS) were comparable (ROC area: 0.94 to 0.96) and superior to plasma PMN-elastase and neopterin, haemodynamics and clinical parameters in predicting the risk for septic complications as early as by the first postoperative day.

Bacterial Infections↗
PubMedDate not supplied

Stimulation of human cardiac adenylate cyclase by vanadate.

Experiments have been carried out to characterize the influence of the positive inotropic trace element vanadium (used as Na3VO4) on beta-adrenergic receptor coupled adenylate cyclase activity from human myocardium. Na3VO4 (10(4)M) stimulates basal activity as well as isoprenaline (10 microM)- and Mg2+ (20 mM) activated enzyme activity 1.5-2.4-fold. In contrast, adenylate cyclase activity in the presence of maximally activating concentrations of Gpp(NH)p (10 microM) cannot be further increased by Na3VO4. The results confirm the assumption (5) that vanadate stimulates adenylate cyclase by interacting with the nucleotide-binding site of this enzyme.

Adenylyl Cyclases↗
PubMedDate not supplied

Significance of NADH-vanadate-oxidoreductase of cardiac and erythrocyte cell membranes.

Vanadate(V), which has positive inotropic, natriuretic and vasoconstrictive effects, is taken up by cardiac cells and erythrocytes in large quantities. Most of the intracellular vanadium is shown to exist as protein-bound vanadyl(IV), however Vanadate (VO3) is a powerful inhibitor of the (Na+ rK+)-ATPase and the Ca++-ATPase, whereas it stimulates adenylate cyclase of cardiac tissue. Vanadyl (VO2+) has no or much less effects on these enzymes. Plasma membranes of cardiac tissue (cat, calf, human) as well as erythrocytes contain an enzyme that converts vanadate(V) to vanadyl(IV) in the presence of NADH but not NADPH. The optimal conditions for this NADH-vanadate-oxidoreductase are: pH 6.8, 1 mM, NADH, 1.5 mM Va3VO4. Mg++ inhibits the enzyme half-maximally at 3 mM, Ca++ stimulates at low and inhibits at high concentrations (half-maximally at 0.8 mM). The enzyme is supposed to be located at the inner side of the cell membrane. Vanadate has been proposed as an ideal regulator of active cation transport across the cell membrane. The finding of a HADH-vanadate-oxidoreductase converting vanadate into the rather inactive vanadyl further supports this hypotheses. The amount of vanadate at active sites of the target enzymes might be responsible for the known vanadate effects.

Animals↗
PubMedDate not supplied

Regulation of active cation flux by vanadate in beating rat heart muscle cells in culture.

Looking for a supposed digitalis-like action of compounds of the trace element vanadium, we have investigated the influence of vanadate (Na3VO4) on beating and on active cation flux of [42K+] and [89Rb+] in cultured rat heart muscle cells: Na3VO4(10(-6)-10(-3)M) exerts a positive chronotropic effect and increases contraction velocity and beating automaticity of the cells. Vanadate-induced alteration of beating is paralleled by stimulated uptake of [42K+] and [86Rb+] up to 75%. This stimulation has to be attributed to increased activity of (Na++)-ATPase and cannot solely be explained by the enhanced beating frequency. In contrast to ouabain, vanadate raises intracellular potassium content up to 15% and prevents cell contractures of ouabain-intoxicated heart muscle cells. The experimental data speak against a possible digitalis-like action of vanadate in cultured rat heart muscle cells.

Animals↗