Search PubMed⌕ Search

Biomedical subjects

K Peter

Publications and source records attributed to K Peter.

At least 19 recordsLinked to original sources
PubMed2002

Cryopreservation of reduced cytochrome C for determination of N-formyl-methionyl-leucyl-phenylalanine-stimulated superoxide anion production in human whole blood.

Various methods are available for measuring the production of reactive oxygen species by phagocytes, but they are limited in their use by the need for their immediate application, cell isolation and of cell-activation by unphysiological stimuli. In addition, after measurement of reactive oxygen metabolites using oxidizing agents, the reduced compounds formed have to be determined during or immediately after their formation. In the present study, an improved cytochrome C assay was investigated which allowed measurements of superoxide anions in whole blood samples following activation of phagocytes by physiological stimuli such as the bacterial tripeptide N-formyl-methionyl-leucyl-phenylalanine (fMLP). The fMLP-stimulated production of superoxide anion (O(2)(-)) showed a sigmoidal-shaped fMLP dose-response curve, and constant O(2)(-) production rates (nmol.1(-1)x10(6) granulocytes) could be determined reliably up to a blood granulocyte concentration of 1 x 10(4) x microl(-1). To allow the determination of reduced cytochrome C later after its formation, the effect of long-term storage at -20 degrees C on the stability of reduced cytochrome C was tested up to 16 weeks. The results obtained show that the determination of reduced cytochrome C in whole blood represents a simple and reliable method. Most importantly, O(2)(-)-reduced cytochrome C can be frozen and stored without any alterations, at least up to 2 weeks. Thus the method seems to be superior to other methods of detection, especially when the experimental conditions do not allow immediate spectrophotometry (e.g. mountain medicine, space medicine). Under such conditions the present assay would allow reliable measurement of reduced cytochrome C, even after weeks of cryopreservation.

Cell Separation↗
PubMed2002

Impact of sepsis, lung injury, and the role of lipid infusion on circulating prostacyclin and thromboxane A(2).

OBJECTIVE: To investigate whether plasma levels of prostacyclin (PGI2) and thromboxane A(2) (TxA2) are a function of the infusion rate of soybean-based fat emulsions, severity of systemic inflammation, and pulmonary organ failure. DESIGN: Prospective, randomized, crossover study. SETTING: Intensive care unit of a university hospital. PATIENTS: Eighteen critically ill patients, ten presenting with severe sepsis, eight with SIRS or sepsis complicated with ARDS. INTERVENTIONS: Patients were randomly assigned to receive rapid fat infusion over 6 h (rFI) or slow fat infusion over 24 h (sFI) along with parenteral nutrition. MEASUREMENTS AND RESULTS: The stable prostanoids 6-keto-PGF1alpha and TxB2 were measured in arterial and mixed venous blood samples, and at 6-h periods trans-pulmonary balances (TPB) were calculated. Free linoleic acid fraction was determined in arterial blood. rFI induced greater increase of linoleic acid than sFI in both groups. Enhanced prostanoid levels and correlations with linoleic acid availabilities were found, however, in ARDS patients only, revealing the highest sepsis- and lung injury scores. Averaged TPB per 24 h was positive in the sepsis group and negative in the ARDS group as rFI induced lowest TPB values for TxB2 at 6 h. CONCLUSION: The quantity of prostanoids formed and their subsequent utilization are dependent on the availability of precursor linoleic acid and are probably affected by the severity of SIRS or sepsis and the existence of pulmonary organ failure, respectively. Because TxA2 might be extracted by the injured lung, rapid infusion of soybean-based fat emulsions should be avoided in patients suffering from severe pulmonary organ failure.

Adult↗
PubMed2002

[Permissive hypotension in severe trauma].

Hemodynamic instability in the polytraumatized patient is a predominant feature and most commonly secondary to blood loss accompanying injury. In these patients restoration of intravascular volume attempting to achieve normal systemic pressure faces the risk of increasing blood loss and thereby potentially affecting mortality. Due to the lack of controlled clinical trials in this field, the growing evidence that "hypotensive resuscitation" results in improved long-term survival and improved neurologic outcome, mainly stems from experimental studies in animals. In patient care, several concepts exist for the reduction of blood loss in conjunction with systemic hypotension: these involve "deliberate hypotension" (synonym "controlled hypotension", used intraoperatively under conditions of normovolemia and stable hemodynamics), "delayed resuscitation" (where the hypotensive period is intentionally prolonged until operative intervention), and "permissive hypotension" (synonym "hypotensive resuscitation", where all kinds of therapy are commenced including fluid therapy, thereby increasing systemic pressure without, however, reaching normotension). In this review the concept of "permissive hypotension" is delineated on the basis of macro- and microcirculatory changes secondary to hypovolemia and low driving pressure, and potential indications as well as limitations for the care of the traumatized patient are discussed.

Blood Pressure↗
PubMed2002

[Electric stimulation acupuncture in peripheral neuropathic pain syndromes. Clinical pilot study on analgesic effectiveness].

AIM: The aim of this pilot study was to investigate the potential value of acupuncture in the treatment of peripheral neuropathic pain. Explorative analysis should provide data for further randomised controlled trials. METHOD: In an uncontrolled clinical trial electroacupuncture was given to 17 patients with chronic neuropathic pain of peripheral origin which was resistant to preceding pain therapy. Patients were treated twice weekly for 4 weeks. Assessment of outcome measurements comprised: Intensity of continuous pain (visual analogue scale, VAS), intensity of pain attacks (VAS), duration of pain attacks, number of pain attacks and changes in mood (VAS). All measures were evaluated by diary (1 week before treatment to 2 weeks after treatment and 1 week at follow up three months after treatment). Changes of global complaints and patients' beliefs in treatment (credibility assessment) were also assessed. RESULTS: At re-evaluation two weeks after treatment, mean continuous pain was reduced by 32.9% and intensity of pain attacks was reduced by 59%. Mean number of daily pain attacks decreased from 4.2 (SD +/- 4.6, 0.14-13.3) before treatment to 2.2 (SD +/- 3.8, 0-7.5) two weeks after treatment. Duration of pain attacks and mood showed no substantial changes. Three months after treatment, continuous pain was reduced by 15.9% and intensity of pain attacks was reduced by 44% compared to baseline. No serious adverse events were observed CONCLUSIONS: On the basis of this small pilot study, trial treatment by electroacupuncture seems to be justified in these patients given a lack of success of standard treatments. The apparent beneficial analgesic effects of electroacupuncture appear to warrant further investigation.

Acupuncture Analgesia↗
PubMed2002

Immune-modulatory actions of arginine in the critically ill.

Current trials of immune-enhancing diets suggest several beneficial clinical effects. These products are associated with a reduction in infectious risk, ventilator days, ICU and hospital stay. However, methodological weaknesses limit the inferences we can make from these studies. Furthermore, improvements in outcomes were largely seen in surgical patients and in patients who tolerated critical amounts of formula. We propose that the beneficial findings cannot easily be extrapolated to other patient populations since there is suggestion from clinical trials that the sickest patients, especially those with severest appearances of sepsis, shock and organ failure may not benefit or may even be harmed. In these conditions we hypothesize that systemic inflammation might be undesirably intensified by immune-enhancing nutrients like arginine in critically ill patients. In this paper, we review the purported effects of arginine on the immune system and organ function to understand the scientific rationale for its inclusion into enteral feeding products. We conclude that patients with the most severe appearances of the systemic inflammatory response syndrome should not receive immune-enhancing substrates which may aggravate systemic inflammation and worsen clinical outcomes.

Arginine↗
PubMed2002

Effects of confinement (110 and 240 days) on neuroendocrine stress response and changes of immune cells in men.

The aim of the study was to evaluate the effects of long-term confinement on stress-permissive neuroendocrine and immune responses in humans. Two groups of four male subjects were confined 240 days (group 240) or 110 days (group 110) in two space modules of 100 or 200 m3, respectively. During confinement, none of the volunteers developed psychic stress as could be examined and verified by a current stress test. However, in group 240 but not in group 110, the diurnal rhythm of cortisol secretion was slightly depressed and the urine excretion of norepinephrine significantly increased. The innate part of the immune system became activated as seen by a rise in the number of circulating granulocytes and the enhanced expression of beta2-integrins. In contrast, the ratio of T-helper to T-suppressor cells decreased. All these effects, observed during confinement, were even more pronounced in both groups when values of endocrinological and immunological parameters were compared between before and 1 wk after the end of the confinement period. Hence, return to normal life exerts pronounced effects to a much higher degree, irrespective of how long or under which conditions individuals were confined. Because the delayed-type hypersensitivity skin reaction against recall antigens remained unaffected, it is to be presumed that confinement appears to induce distinct sympathoadrenergic activation and immunological changes but no clinically relevant immunosuppression.

Adult↗
PubMed2002

Ropivacaine 7.5 mg/ml versus bupivacaine 5 mg/ml for interscalene brachial plexus block--a comparative study.

We investigated ropivacaine 75 mg/ml in comparison with bupivacaine 5 mg/ml in patients receiving interscalene brachial plexus block (ISB) and general anaesthesia. In this randomized, double-blind, prospective clinical trial, each patient received an ISB block according to the technique originally described by Winnie and a catheter technique as per Meier. The rapidity of onset and the quality of sensory and motor block were determined. After general anaesthesia had been induced further parameters evaluated were consumption of local anaesthetic, opioid and neuromuscular blocking drug. After arrival in the recovery room, the patients were assessed for intensity of pain using a visual analog scale (VAS). One hundred and twenty patients were included in the study. The onset and development of sensory block was similar in both groups. Development and quality of motor block was also nearly identical for both local anaesthetics. Consumption of neuromuscular blocking drug and opioid did not differ between ropivacaine and bupivacaine. In the recovery room the mean pain score was less than 25 in both groups. There were no significant differences in terms of onset and quality of sensory or motor block during the intraoperative and early postoperative period. In addition we did not identify any side-effects related to the administration of the local anaesthetics. Ropivacaine 7.5 mg/ml and bupivacaine 5mg/ml proved to be nearly indistinguishable when administered for interscalene brachial plexus block.

Adult↗
PubMed2001

Intrinsic activating properties of GP IIb/IIIa blockers.

Potential intrinsic activating properties are probably the most controversially discussed issues with respect to GP IIb/IIIa blockers, especially since clinical trials with oral GP IIb/IIIa blockers revealed disappointing results. Based on the finding that currently clinically used GP IIb/IIIa blockers are ligand mimetics, experimental data are discussed, demonstrating an intrinsic activating effect of ligand mimetic GP IIb/IIIa blockers that potentially results in fibrinogen binding to alpha(IIb)beta(3) and in platelet aggregation. Furthermore, the inhibitory effect of aspirin on GP IIb/IIIa blocker-induced platelet aggregation is discussed as a clinically relevant finding. Finally, the potential association of GP IIb/IIIa blocker-induced thrombocytopenia with platelet activation is described.

Antibodies, Monoclonal↗
PubMed2001

Induction of a cytotoxic T-cell response to HIV-1 proteins with short synthetic peptides and human compatible adjuvants.

The goal of this study was the induction of a strong CTL response against multiple CTL epitopes present in HIV proteins using short synthetic peptides. Four HLA-A2.1 restricted peptides (RT 476-484, p17 77-85, gp41 814-823, RT 956-964) that showed stable binding to the HLA-A2.1 molecule in an in vitro binding assay were able to elicit a strong specific immune response in HLA-A2.1 transgenic mice when injected with IFA or Montanide. The use of biodegradable microspheres (MS) as adjuvant was also successfully tested for all peptides. When the peptides were injected as a mixture the response was weaker as compared to individual injections of the peptides indicating the occurrence of immunodominance (ID). We are currently investigating whether ID can be overcome by a combined injection of peptide loaded MS with different release patterns. Taken together, it seems feasible to induce a specific CTL response in HLA-A2.1 transgenic mice against several HIV proteins using short synthetic peptides and human compatible adjuvants.

AIDS Vaccines↗
PubMed2001

[GPIIb/IIIa blockers for optimizing thrombolysis in acute myocardial infarct].

BACKGROUND: Thrombolytic therapy is an established strategy for the treatment of acute myocardial infarction. GPIIB/IIIA BLOCKERS + MODERN THROMBOLYTIC AGENTS: At present, the most attractive development for optimizing thrombolytic therapy includes the use of GPIIb/IIIa blockers in combination with modern thrombolytic agents such as alteplase and reteplase. The review summarizes the available results of clinical studies using standard doses of thrombolytic agents (TAMI 8, IMPACT-AMI, and PARADIGM) or reduced dosages of thrombolytic agents (TIMI 14 and SPEED) for combination therapy. The review also focuses on the implications of the combination therapy for coronary angioplasty immediately following coronary thrombolysis.

Abciximab↗
PubMed2001

[Low alkali-hydroxide content in soda limes does not lead to reduction of compound A formation from sevoflurane during low-flow anesthesia].

The alkali hydroxide content in soda lime induces Compound A formation from Sevoflurane (Sevo). This study was designed to answer the question if the use of potassium hydroxide-free Soda Lime (SL) would lead to lower Compound A levels as compared to Sodasorb (SO). A total of 30 patients scheduled for elective laparoscopic cholecystectomy received Sevo anaesthesia under low-flow conditions (0.8 l/min fresh gas flow). Each absorbent was used in 15 patients, but 3 patients of the SO group were excluded due to technical problems with Compound A analysis. Hemodynamic parameters, parameters of ventilation and gas concentrations were documented. Compound A concentrations were measured by gas chromatography from gas samples before Sevo application and 20, 40, 60, 90 and 120 min after low-flow start. Mean endtidal Sevo concentrations were 1.94 +/- 0.17 (SO) and 1.97 +/- 0.15 (SL) vol %, the total anaesthetic exposition was 1.52 +/- 0.36 (SO) and 1.64 +/- 0.47 (SL) MAC-h (n.s). The maximum Compound A concentration was significantly higher in SL group (19.6 +/- 2.8 vs. 11.7 +/- 4.1 ppm, p < 0.001). Therefore, elimination of potassium hydroxide from carbon dioxide absorbents alone did not lead to a reduction of Compound A formation during low-flow anaesthesia.

Anesthesia, Inhalation↗
PubMed2001

Intensive care after minimally invasive and conventional coronary surgery: a prospective comparison.

OBJECTIVE: The purpose of this study was to compare the intensive care course of patients after minimally invasive coronary surgery to conventional coronary artery bypass grafting. DESIGN: Prospective observational study. SETTING: Intensive care unit of a university hospital. PATIENTS AND PARTICIPANTS: One hundred and five patients with two-vessel disease consecutively scheduled for elective coronary bypass surgery were enrolled. INTERVENTIONS: Two techniques of revascularization were performed: the Octopus procedure via median sternotomy without cardiopulmonary bypass (n = 52) and conventional coronary artery bypass grafting CABG (n = 53). MEASUREMENTS AND RESULTS: Three major categories describing the patients' postoperative course were defined: (1) clinical and laboratory findings, i.e., transfusion rate, catecholamine support, duration of ventilation, Simplified Acute Physiology Score II (SAPS II), serum levels of cardiac enzymes and lactic acid; (2) postoperative complications, i.e., incidence of myocardial infarction (MI), atrial fibrillation (AF), and neurological deficits; (3) this category was defined as "the extent of care" as represented by the Therapeutic Intervention Scoring System (TISS), and the length of stay in the ICU and in the hospital. In the Octopus group significantly lower figures were noted for duration of ventilation [6.1(5.5/9.5) vs 10.2(8.2/11.8) h], cardiac enzymes (CK-MB-Mass [5.1(2.0/8.3) vs 31.3(21.4/39.3) ng/ml], and lactic acid [2.0(1.5/3.3) vs 3.2(2.2/6.5) mmol/l]), incidence of AF (2/52 vs 9/53), and neurological deficits (0/52 vs 4/53), TISS score [72(44/83) vs 84(73/93)], LOS in the ICU [2(1/2) vs 2(2/2) days], and in the hospital [6(5/9) vs 9(8/12) days]. Catecholamine support, SAPS II scores, and incidence of MI of each group did not differ significantly. CONCLUSIONS: Off-pump coronary surgery via the Octopus technique was superior to conventional CABG regarding the course of patients in the early postoperative period. This implies benefits for the patients and the entire healthcare system.

APACHE↗
PubMed2001

Ecarin clotting time but not aPTT correlates with PEG-hirudin plasma activity.

BACKGROUND: Novel antithrombotic agents such as hirudin have shown promise in the therapy of acute coronary syndromes. PEG-hirudin (polyethyleneglycol conjugated hirudin) has been developed to provide a longer plasma half-life and more stable antithrombotic plasma levels. Privious trials indicated a narrow therapeutic window for hirudin and a number of aPTT (activated partial thromboplastin time)-monitored trials investigating hirudin in acute coronary syndromes had to be stopped because of intracranial bleeding complications. OBJECTIVES: The present study evaluates the ecarin clotting time (ECT), a parameter based on the conversion of prothrombin by the snake venom enzyme ecarin, for the monitoring of PEG-hirudin therapy. METHODS: Plasma from either healthy volunteers (n=20) or from patients (n=10) suffering from unstable angina pectoris (UAP) was spiked with increasing PEG-hirudin concentrations. In a prospective randomized clinical trial patients with UAP were treated with intravenous PEG-hirudin or heparin over 72 hours. Patients were randomized to the following treatment groups: (1) heparin control group, n=15; (2) PEG-hirudin low dose (0.1 mg/kg bolus, 0.01 mg/kg/h infusion), n=19; (3) intermediate dose (0.15 mg/kg and 0.015 mg/kg/h), n=17; 4) high-dose (0.2 mg/kg and 0.02 mg/kg/h), n=16. Spiked plasma samples and plasma from UAP patients treated with i.v. PEG-hirudin were analyzed for aPTT, ECT, and PEG-hirudin levels. RESULTS: A linear correlation up to the highest therapeutic concentrations could be observed between PEG-hirudin plasma concentrations and the ECT. This was true for both plasma samples spiked with PEG-hirudin in vitro as well as for samples taken from patients treated with i.v. PEG-hirudin (correlation coefficient 0.9, respect.) In contrast the aPTT did not show a reliable linear correlation to PEG-hirudin concentrations. CONCLUSION: Monitoring of PEG-hirudin therapy by ECT may help to avoid inadequate anticoagulation or overdosing. Thus, the safety and efficacy profile of PEG-hirudin therapy is likely to be enhanced by ECT monitoring.

Angina, Unstable↗
PubMed2001

Effects of intravenous fat emulsions on lung function in patients with acute respiratory distress syndrome or sepsis.

OBJECTIVE: To investigate whether rapid or slowly infused intravenous fat emulsions affect the ratio of prostaglandin I2/thromboxane A2 in arterial blood, pulmonary hemodynamics, and gas exchange. DESIGN: Prospective, controlled, randomized, crossover study. SETTING: Operative intensive care unit of a university hospital. PATIENTS: Eighteen critically ill patients. Ten patients were stratified with severe sepsis, and eight patients had acute respiratory distress syndrome (ARDS). INTERVENTIONS: Patients were assigned randomly to receive intravenous fat emulsions (0.4 x resting energy expenditure) over 6 hrs (rapid fat infusion) or 24 hrs (slow fat infusion) along with a routine parenteral nutrition regimen, by using a crossover study design. MEASUREMENTS AND MAIN RESULTS: Systemic and pulmonary hemodynamics as well as gas exchange measurements were recorded via respective indwelling catheters. Arterial thromboxane B2 and 6-keto-prostaglandin-F1alpha plasma concentrations were obtained by radioimmunoassay, and 6-keto-prostaglandin-F1alpha/thromboxane B2 ratios (P/T ratios) were calculated. Data were collected immediately before and 6, 12, 18, and 24 hrs after onset of fat infusion. In the ARDS group, P/T ratio increased by rapid fat infusion. Concomitantly, pulmonary shunt fraction, alveolar-arterial oxygen tension difference [P(a-a)o2]/Pao2, and cardiac index increased as well, whereas pulmonary vascular resistance and Pao2/Fio2 declined. After slow fat infusion, a decreased P/T ratio was revealed. This was accompanied by decreased pulmonary shunt fraction, lowered P(a-a)o2/Pao2, and increased Pao2/Fio2. Correlations between plasma concentrations of 6-keto-prostaglandin-F1alpha or thromboxane B2 and measures of respiratory performance could be shown during rapid and slow fat infusion, respectively. In the sepsis group, the P/T ratio remained unchanged at either infusion rate, but pulmonary shunt fraction and P(a-a)o2/Pao2 decreased after rapid fat infusion, whereas Pao2/Fio2 increased. CONCLUSION: Pulmonary hemodynamics and gas exchange are related to changes of arterial prostanoid levels in ARDS patients, depending on the rate of fat infusion. In ARDS but not in sepsis patients clear of pulmonary organ failure, a changing balance of prostaglandin I2 and thromboxane A2 may modulate gas exchange, presumably via interference with hypoxic pulmonary vasoconstriction.

APACHE↗
PubMed2001

Simulated microgravity, psychic stress, and immune cells in men: observations during 120-day 6 degrees HDT.

Because 6 degrees head-down tilt (HDT) is an established method to mimic low gravity on earth, the aim of the present study was to determine the effects of 120-day HDT on psychic stress and peripheral blood immune cells in six healthy male volunteers. Psychological state was assessed by a current stress test, and cortisol was measured in saliva. During HDT, all volunteers developed psychic stress, and the diurnal rhythm of cortisol secretion was significantly altered. In addition, urine excretion of dopamine and norepinephrine increased. The innate part of the immune response was activated, as evidenced by the increase in the expression of beta(2)-integrins on polymorphonuclear leukocytes and a rise in the number of circulating natural killer (NK) cell lymphocytes. The ratio of T-helper to T-cytotoxic and T-suppressor cells decreased, whereas no changes in T and B lymphocytes were observed. Plasma levels of interleukin-6 increased significantly and returned to basal levels after the end of the HDT period. Thus 6 degrees HDT appears to be a valid model to induce psychic stress and neuroendocrine-related changes in the immune system, changes that might also be encountered by astronauts and cosmonauts during long-duration spaceflights.

Adult↗
PubMed2001

Effects of hypertonic saline on expression of human polymorphonuclear leukocyte adhesion molecules.

Hypertonic saline prevents vascular adherence of neutrophils and ameliorates ischemic tissue injury. We hypothesized that hypertonic saline attenuates N-formyl-methionyl-leucyl-phenylalanine (fMLP)-stimulated expression of adhesion molecules on human polymorphonuclear leukocytes (PMNLs). fMLP-stimulated up-regulation of beta2-integrins was diminished by hypertonic saline but not by hypertonic choline chloride-, mannitol-, or sucrose-modified Hanks' buffered salt solution. Shedding of L-selectin was decreased by hypertonic saline and choline chloride but not by hypertonic mannitol or sucrose. When the effects of hypertonic sodium chloride- and choline chloride-modified media were compared, neither solution affected fMLP-receptor binding but both equally inhibited fMLP-stimulated increase in intracellular calcium, ionophore A23187, and phorbol myristate acetate (PMA)-stimulated numerical up-regulation of beta2-integrins. Analysis of mitogen-activated protein (MAP) kinases p38 and p44/42 for phosphorylation revealed that hypertonic solutions did not differ in preventing fMLP-stimulated increases in phospho-p38 and phospho-p44/42. Resting PMNLs shrunk by hypertonic saline increased their volume during incubation and further during chemotactic stimulation. Addition of amiloride further enhanced inhibition of up-regulation of beta2-integrins. No fMLP-stimulated volume changes occurred in PMNLs exposed to hypertonic choline chloride, resulting in significant cell shrinkage. Results suggest a sodium-specific inhibitory effect on up-regulation of beta2-integrins of fMLP-stimulated PMNLs, which is unlikely to be caused by alterations of fMLP receptor binding, decrease in cytosolic calcium, attenuation of calcium or protein kinase C-dependent pathways, suppression of p38- or p44/42 MAP kinase-dependent pathways, or cellular ability to increase or decrease volumes.

CD18 Antigens↗