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Biomedical subjects

T Zielinski

Publications and source records attributed to T Zielinski.

At least 19 recordsLinked to original sources
PubMed2004

The concept of a clinical round as a virtual, interactive web-based, e-learning model for interdisciplinary teaching.

The demonstration of patient case reports in the course of a clinical round is an essential part of teaching medicine and dentistry. However, suitable live patients with particular problems are not always available at a time when teaching is taking place. This project therefore had the objective of establishing a web-based, virtual e-learning concept for demonstrating case reports independent of time and place, with the possibility of an interactive examination, diagnosis, and interdisciplinary therapy decision making for medical and dental students. Anonymized case reports of diseases in the oral and maxillofacial region and the interdisciplinary treatment were digitized and prepared in a web-based format. The technical aspect was based on connecting flash modules with videos and animation, and monitoring through HTML and Javascript. Due to the modular concept and the programming used, the learning environment was independent of platform and open. Independent formats (.swf, .avi, .mpeg, etc.) were integrated into the individual modules. According to a hierarchic decision system, the user was guided interactively to the diagnosis through a differential diagnostic exclusion process. Sound was digitized and integrated in mp3 compressed form in the 3D models for lip-synchronous speech output. The speech output was connected with a virtual 3D tutor that acted in an advisory capacity in reaching a diagnosis and determining therapy. Further sources of information and literature with abstracts or pdf files of the subject-related publications were inserted to ensure that the teaching was objective. To conclude the virtual clinical round, a check on learning success was conducted in the form of a multimedia multiple choice test.

Computer-Assisted Instruction↗
PubMed2001

The generation of superoxide anion in blood platelets in response to different forms of Proteus mirabilis lipopolysaccharide: effects of staurosporin, wortmannin, and indomethacin.

Lipopolysaccharide (LPS), the major component of the outer membrane of Gram-negative bacteria may activate blood platelets. The aim of our study was to evaluate the effects of different forms of Proteus mirabilis LPS and isolated lipid A and polysaccharide part on the production of superoxide radicals in blood platelets and to estimate the role staurosporin, wortmannin and indomethacin on this process. We compared the generation of superoxide radicals in platelets treated with LPS after preincubation with inhibitors of the signal transduction pathways, namely staurosporin (inhibitor of protein kinase C), wortmannin (inhibitor of phosphoinositide 3-kinase), and indomethacin (inhibitor of cycloxygenase). Our results demonstrate that all LPS molecules and their fragments caused a stimulation of O2- generation in platelets (P<.5). LPSS1959 had the strongest stimulatory effect. Straurosporin and wortmannin, but not indomethacin inhibited O2- production in LPS-stimulated platelets. Staurosporin (8 nM) and wortmannin (50 nM) caused about 50% inhibition of thrombin-induced O2- generation in platelets, while indomethacin (10 microM) had only a slight inhibitory effect on this process. Our results provide support that in LPS- and thrombin-activated platelets, at least part of O2- generation in platelets, while indomethacin (10 microM) had only a slight inhibitory effect on this process. Our results provide support that in LPS- and thrombin-activated platelets, at least part of O2- is generated due to the activation of the enzymes (protein kinase C and phosphoinositide 3-kinase) involved in signal transduction pathway. Cycloxygenase seems to be not involved in this process.

Androstadienes↗
PubMed2001

Adhesion of thrombin-stimulated and unstimulated blood platelets to collagen in the presence of Proteus mirabilis lipopolysaccharides.

Adhesion of blood platelets to collagen may be involved in pathogenesis of septic shock after damage of endothelial cells by LPS or inflammatory cytokines. Therefore, analysis of platelet adhesion in the presence of endotoxin seems to be of great importance. We studied in vitro the effects of LPSs (S1959, R110, R45) from Proteus mirabilis (smooth and rough types differing significantly in their composition) on the adhesion of unstimulated and thrombin-stimulated platelets to collagen. The adhesion was measured by a static method as absorbance of cell attached proteins. In this work we report that adhesion of resting platelets to collagen was stimulated by all tested LPSs. The effects were dependent on the doses of LPSs. In the presence of LPSs the inhibition of adhesion of thrombin-treated platelets to collagen was observed. The results presented in this paper indicate that LPSs from Proteus mirabilis may act directly on blood platelets and stimulate adhesion of resting platelets to collagen. On the other hand, LPSs can have an inhibitory effect on adhesion of thrombin-stimulated platelets to collagen.

Animals↗
PubMed2001

The effects of positive end-expiratory pressure during active compression decompression cardiopulmonary resuscitation with the inspiratory threshold valve.

UNLABELLED: The use of an inspiratory impedance threshold valve (ITV) during active compression-decompression (ACD) cardiopulmonary resuscitation (CPR) improves perfusion pressures, and vital organ blood flow. We evaluated the effects of positive end-expiratory pressure (PEEP) on gas exchange, and coronary perfusion pressure gradients during ACD + ITV CPR in a porcine cardiac arrest model. All animals received pure oxygen intermittent positive pressure ventilation (IPPV) at a 5:1 compression-ventilation ratio during ACD + ITV CPR. After 8 min, pigs were randomized to further IPPV alone (n = 8), or IPPV with increasing levels of PEEP (n = 8) of 2.5, 5.0, 7.5, and 10 cm H(2)O for 4 consecutive min each, respectively. Mean +/- SEM arterial oxygen partial pressure decreased in the IPPV group from 150 +/- 30 at baseline after 8 min of CPR to 110 +/- 25 torr at 24 min, but increased in the PEEP group from 115 +/- 15 to 170 +/- 25 torr with increasing levels of PEEP (P <0.02 for comparisons within groups). Mean +/- SEM diastolic aortic minus diastolic left ventricular pressure gradient was significantly (P < 0.001) higher after the administration of PEEP (24 +/- 0 vs 17 +/- 1 mm Hg with 5 cm H(2)O of PEEP, and 26 +/- 0 vs 17 +/- 1 mm Hg with 10 cm H(2)O of PEEP), whereas the diastolic aortic minus right atrial pressure gradient (coronary perfusion pressure) was comparable between groups. Furthermore, systolic aortic pressures were significantly (P < 0.05) higher with 10 cm H(2)O of PEEP when compared with IPPV alone (68 +/- 0 vs 59 +/- 2 mm Hg). In conclusion, when CPR was performed with devices designed to improve venous return to the chest, increasing PEEP levels improved oxygenation. Moreover, PEEP significantly increased the diastolic aortic minus left ventricular gradient and did not affect the decompression phase aortic minus right atrial pressure gradient. These data suggest that PEEP reduces alveolar collapse during ACD + ITV CPR, thus leading to an increase in indirect myocardial compression. IMPLICATIONS: Inspiratory impedance during active compression-decompression cardiopulmonary resuscitation improves perfusion pressures, and vital organ blood flow during cardiac arrest. Increasing levels of positive end-expiratory pressure during performance of active compression-decompression cardiopulmonary resuscitation with an inspiratory impedance valve improves oxygenation, and increases the diastolic aortic-left ventricular pressure gradient and systolic arterial blood pressure.

Air Pressure↗
PubMed2001

Improving standard cardiopulmonary resuscitation with an inspiratory impedance threshold valve in a porcine model of cardiac arrest.

To improve the efficiency of standard cardiopulmonary resuscitation (CPR), we evaluated the potential value of impeding respiratory gas exchange selectively during the decompression phase of standard CPR in a porcine model of ventricular fibrillation. After 6 min of untreated cardiac arrest, anesthetized farm pigs weighing 30 kg were randomized to be treated with either standard CPR with a sham valve (n = 11) or standard CPR plus a functional inspiratory impedance threshold valve (ITV(TM)) (n = 11). Coronary perfusion pressure (CPP) (diastolic aortic minus right atrial pressure) was the primary endpoint. Vital organ blood flow was assessed with radiolabeled microspheres after 6 min of CPR, and defibrillation was attempted 11 min after starting CPR. After 2 min of CPR, mean +/- SEM CPP was 14 +/- 2 mm Hg with the sham valve versus 20 +/- 2 mm Hg in the ITV group (P < 0.006). Significantly higher CPPs were maintained throughout the study when the ITV was used. After 6 min of CPR, mean +/- SEM left ventricular and global cerebral blood flows were 0.10 +/- 0.03 and 0.19 +/- 0.03 mL. min(-1). g(-1) in the Control group versus 0.19 +/- 0.03 and 0.26 +/- 0.03 mL. min(-1). g(-1) in the ITV group, respectively (P < 0.05). Fifteen minutes after successful defibrillation, 2 of 11 animals were alive in the Control group versus 6 of 11 in the ITV group (not significant). In conclusion, use of an inspiratory impedance valve during standard CPR resulted in a marked increase in CPP and vital organ blood flow after 6 min of cardiac arrest.

Animals↗
PubMed2001

Comparison of epinephrine with vasopressin on bone marrow blood flow in an animal model of hypovolemic shock and subsequent cardiac arrest.

OBJECTIVE: The intraosseous route is an emergency alternative for the administration of drugs and fluids if vascular access cannot be established. However, in hemorrhagic shock or after vasopressors are given during resuscitation, bone marrow blood flow may be decreased, thus impairing absorption of intraosseously administered drugs. In this study, we evaluated the effects of vasopressin vs. high-dose epinephrine in hemorrhagic shock and cardiac arrest on bone marrow blood flow. DESIGN: Prospective, randomized laboratory investigation that used an established porcine model for measurement of hemodynamic variables and organ blood flow. SETTING: University hospital laboratory. SUBJECTS: Fourteen pigs weighing 30 +/- 3 kg. INTERVENTIONS: Radiolabeled microspheres were injected to measure bone marrow blood flow during a prearrest control period and during hypovolemic shock produced by rapid hemorrhage of 35% of the estimated blood volume. In the second part of the study, ventricular fibrillation was induced; after 4 mins of untreated cardiac arrest and 4 mins of standard cardiopulmonary resuscitation, a bolus dose of either 200 microg/kg epinephrine (n = 6) or 0.8 units/kg vasopressin (n = 6) was administered. Defibrillation was attempted 2.5 mins after drug administration, and blood flow was assessed again at 5 and 30 mins after successful resuscitation. MEASUREMENTS AND MAIN RESULTS: Mean +/- sem bone marrow blood flow decreased significantly during induction of hemorrhagic shock from 14.4 +/- 4.1 to 3.7 +/- 1.8 mL.100 g-1.min-1 in the vasopressin group and from 18.2 +/- 4.0 to 5.2 +/- 1.0 mL.100 g-1.min-1 in the epinephrine group (p =.025 in both groups). Five minutes after return of spontaneous circulation, mean +/- sem bone marrow blood flow was 3.4 +/- 1.1 mL.100 g-1.min-1 after vasopressin and 0.1 +/- 0.03 mL.100 g-1.min-1 after epinephrine (p =.004 for vasopressin vs. epinephrine). At the same time, bone vascular resistance was significantly (p =.004) higher in the epinephrine group when compared with vasopressin (1455 +/- 392 vs. 43 +/- 19 mm Hg. mL-1.100 g.min, respectively). CONCLUSIONS: Bone blood flow responds actively to both the physiologic stress response of hemorrhagic shock and vasopressors given during resuscitation after hypovolemic cardiac arrest. In this regard, bone marrow blood flow after successful resuscitation was nearly absent after high-dose epinephrine but was maintained after high-dose vasopressin. These findings emphasize the need for pressurized intraosseous infusion techniques, because bone marrow blood flow may not be predictable during hemorrhagic shock and drug therapy.

Animals↗
PubMed2001

Traumatic tricuspid valve insufficiency: case report.

A 30-year old man underwent a head-on motor accident and was admitted to hospital, where he was successfully treated for several injuries. He was discharged home with slight tricuspid regurgitation, without signs of hemodynamic decompensation, and required no further treatment. Five years later he was admitted to the National Institute of Cardiology due to overt right ventricular failure secondary to tricuspid valve regurgitation. After several unsuccessful attempts at papillary muscle and chordal repair, a 33-mm SJM Biocor valve was implanted. This case history underlines the value of echocardiography, even after blunt chest trauma without cardiac symptoms. A good functional result can be achieved years after onset of traumatic valve insufficiency, but early diagnosis and surgical treatment increases the feasibility of tricuspid valve repair rather than replacement, and also prevents progressive deterioration of right ventricular function.

Accidents, Traffic↗
PubMed2000

Use of an inspiratory impedance threshold valve during cardiopulmonary resuscitation: a progress report.

Building upon studies on the mechanism of active compression-decompression (ACD) cardiopulmonary resuscitation, a new inspiratory impedance threshold valve has been developed to enhance the return of blood to the thorax during the decompression phase of CPR. Use of this device results in a greater negative intrathoracic pressure during chest wall decompression. This leads to improved vital organ perfusion during both standard and ACD CPR. Animal and human studies suggest that this simple device increases cardiopulmonary circulation by harnessing more efficiently the kinetic energy of the outward movement of the chest wall during standard CPR or active chest wall decompression. When used in conjunction with ACD CPR during clinical evaluation, addition of the impedance valve resulted in sustained systolic pressures of greater than 100 mmHg and diastolic pressures of greater than 55 mmHg. The new valve may be beneficial in patients in asystole or shock refractory ventricular fibrillation, when enhanced return of blood flow to the chest is needed to 'prime the pump'. The potential long-term benefits of this new valve remain under investigation.

Airway Resistance↗
PubMed2000

Vasopressin improves survival after cardiac arrest in hypovolemic shock.

UNLABELLED: Survival after hypovolemic shock and cardiac arrest is dismal with current therapies. We evaluated the potential benefits of vasopressin versus large-dose epinephrine in hemorrhagic shock and cardiac arrest on vital organ perfusion, and the likelihood of resuscitation. In 18 pigs, 35% of the estimated blood volume was withdrawn over 15 min and ventricular fibrillation was induced 5 min later. After 4 min of cardiac arrest and 4 min of standard cardiopulmonary resuscitation, a bolus dose of either 200 microg/kg epinephrine (n = 7), 0.8 unit/kg vasopressin (n = 7), or saline placebo (n = 4) was administered in a blinded, randomized manner. Defibrillation was attempted 2.5 min after drug administration, and all animals were subsequently observed for 1 h without further intervention. Spontaneous circulation was restored in 7 of 7 vasopressin animals, in 6 of 7 epinephrine pigs, and in 0 of 4 placebo swine. At 5 and 30 min after return of spontaneous circulation, median (minimum and maximum) renal blood flow after epinephrine was 2 (0-31), and 2 (0-48) mL. 100 g(-1). min(-1), respectively; and after vasopressin 96 (12-161), and 44 (16-105) mL. 100 g(-1). min(-1), respectively (P: <.01 between groups). Epinephrine animals developed a profound metabolic acidosis by 15 min after return of spontaneous circulation (mean arterial pH, 7.11 +/- 0.01), and by 60 min all epinephrine-treated animals had died. The vasopressin pigs had (P: = 0.015) less acidosis (pH = 7.26+/-0. 04) at corresponding time points, and all survived > or =55 min (P: < 0. 01). In conclusion, treatment of hypovolemic cardiac arrest with vasopressin, but not with large-dose epinephrine or saline placebo, resulted in sustained vital organ perfusion, less metabolic acidosis, and prolonged survival. Based on these findings, clinical evaluation of vasopressin during hypovolemic cardiac arrest may be warranted. IMPLICATIONS: The chances of surviving cardiac arrest in hemorrhagic shock are considered dismal without adequate fluid replacement. However, treatment of hypovolemic cardiac arrest with vasopressin, but not with large-dose epinephrine or saline placebo, resulted in sustained vital organ perfusion and prolonged survival in an animal model of suspended infusion therapy.

Animals↗
PubMed2000

Improving the efficiency of cardiopulmonary resuscitation with an inspiratory impedance threshold valve.

In an effort to improve the efficiency of cardiopulmonary resuscitation (CPR), a new inspiratory impedance threshold valve has been developed to enhance the return of blood to the thorax during the chest decompression phase. This new device enhances negative intrathoracic pressure during chest wall recoil or the decompression phase, leading to improved vital organ perfusion during both standard CPR and active compression-decompression CPR. With active compression-decompression CPR, addition of the impedance threshold valve results in sustained diastolic pressures of >55 mm Hg in patients in cardiac arrest. The new valve shows promise for patients in asystole or shock refractory ventricular fibrillation, when enhanced return of blood flow to the chest is needed to "prime the pump." The potential long-term benefits of this new valve remain under study.

Airway Resistance↗
PubMed2000

Comparison of epinephrine and vasopressin in a pediatric porcine model of asphyxial cardiac arrest.

OBJECTIVE: This study was designed to compare the effects of vasopressin vs. epinephrine vs. the combination of epinephrine with vasopressin on vital organ blood flow and return of spontaneous circulation in a pediatric porcine model of asphyxial arrest. DESIGN: Prospective, randomized laboratory investigation using an established porcine model for measurement of hemodynamic variables, organ blood flow, blood gases, and return of spontaneous circulation. SETTING: University hospital laboratory. SUBJECTS: Eighteen piglets weighing 8-11 kg. INTERVENTIONS: Asphyxial cardiac arrest was induced by clamping the endotracheal tube. After 8 mins of cardiac arrest and 8 mins of cardiopulmonary resuscitation, a bolus dose of either 0.8 units/kg vasopressin (n = 6), 200 microg/kg epinephrine (n = 6), or a combination of 45 microg/kg epinephrine with 0.8 units/kg vasopressin (n = 6) was administered in a randomized manner. Defibrillation was attempted 6 mins after drug administration. MEASUREMENTS AND MAIN RESULTS: Mean +/- SEM coronary perfusion pressure, before and 2 mins after drug administration, was 13 +/- 2 and 23 +/- 6 mm Hg in the vasopressin group; 14 +/- 2 and 31 +/- 4 mm Hg in the epinephrine group; and 13 +/- 1 and 33 +/- 6 mm Hg in the epinephrine-vasopressin group, respectively (p = NS). At the same time points, mean +/- SEM left ventricular myocardial blood flow was 44 +/- 31 and 44 +/- 25 mL x min-(1) x 100 g(-1) in the vasopressin group; 30 +/- 18 and 233 +/- 61 mL x min(-1) x 100 g(-1) in the epinephrine group; and 36 +/- 10 and 142 +/- 57 mL x min(-1) x 100 g(-1) in the epinephrine-vasopressin group (p < .01 epinephrine vs. vasopressin; p < .02 epinephrine-vasopressin vs. vasopressin). Total cerebral blood flow trended toward higher values after epinephrine-vasopressin (60 +/- 19 mL x min(-1) x 100 g(-1)) than after vasopressin (36 +/- 17 mL x min(-1) x 100 g(-1)) or epinephrine alone (31 +/- 7 mL x min(-1) x 100 g(-1); p = .07, respectively). One of six vasopressin, six of six epinephrine, and four of six epinephrine-vasopressin-treated animals had return of spontaneous circulation (p < .01, vasopressin vs. epinephrine). CONCLUSIONS: Administration of epinephrine, either alone or in combination with vasopressin, significantly improved left ventricular myocardial blood flow during cardiopulmonary resuscitation. Return of spontaneous circulation was significantly more likely in epinephrine-treated pigs than in animals resuscitated with vasopressin alone.

Adrenergic Agonists↗
PubMed1998

[Quality control and documentation of effectiveness of bacterial autovaccines with the use of flow cytometry].

Autovaccines are bacterial preparations derived from non pathogenic autologous bacteria of human origin. In the course of microbiological therapy these individual bacterial vaccines are mainly used in conditions of chronic inflammatory disorders of the respiratory or gastrointestinal tract as well as allergic diseases. Being autologous bacterial preparations from the patients own flora the control of batch variabilities of these individual products represents a special challenge for the manufacturer. A flow cytometric method suitable for batch control of autovaccines is described. The method is based upon the determination of the de novo expression of the CD69 antigen on different leucocyte subpopulations in whole blood cultures after preincubation of cells with different batches of autovaccines. Thus, manufacturers of autovaccines and other microbial preparations are able to reliably control batch variability and immunological activity of such products in accordance with drug regulations. The results of this study highlight the pharmaceutical quality of the individual therapeutic agent autovaccine.

Antigens, CD↗
PubMed1997

The meaning of ambulatory care sensitive admissions: urban and rural perspectives.

Ambulatory care sensitive admission rates have been proposed as measures of access to health care. To test this, admissions for ambulatory care sensitive conditions (ACSC) were analyzed by multiple linear regression. The percentage of population below 200 percent of the federally defined poverty level, the percentage of black people, and the number of primary care providers per 1,000 population were found to be positively associated with ACSC admissions. Population density was negatively associated with ACSC admissions. There was no association between the location of the ZIP code in a health professional shortage area and ACSC admissions. Proximity to the hospital was found to be positively associated with ACSC admissions but was examined only in the most rural ZIP code group. The significant independent variables and the direction of their effects were the same across all ZIP code groups. The analysis suggests that high ACSC admissions may be a reflection of deficits in one or more of the following areas: primary care availability, accessibility, or appropriateness. In-depth study is needed to determine the relative importance of these factors in a given geographical area. There also may be environmental and social factors external to the health care system that contribute to ACSC admissions. The findings suggest that ACSC should be used cautiously as a measure of primary care system needs, and in conjunction with other health, demographic, or service utilization data.

Adolescent↗
PubMed1996

Valve replacement for aortic stenosis with severe congestive heart failure and pulmonary hypertension.

BACKGROUND AND AIMS OF THE STUDY: Significant pulmonary hypertension in aortic stenosis is evidence of severe dysfunction of the left ventricle. It is also a predictor of a bad prognosis in the natural course of the disease. This study was performed to evaluate the changes in the hemodynamic parameters of pulmonary circulation at rest and effort in patients who had significant pulmonary hypertension preoperatively and underwent valve replacement. MATERIALS AND METHODS: The study consists of 11 male patients with aortic stenosis with an average peak transvalvular gradient of 68 mmHg and impaired left ventricular function (mean ejection fraction 38%). Six patients were in NYHA functional class III, and five were in class IV. The patients underwent Swan-Ganz catheterization before urgent valve replacement. RESULTS: Significant pulmonary hypertension was found in all subjects, and a below normal cardiac index in eight. Urgent valve replacement was performed in all patients: two of them were operated on during pulmonary edema and cardiogenic shock which developed soon after diagnosis-one of them died. Patients were followed up six months after surgery, and all of them showed major clinical improvement (six in NYHA class I, four in class II). Mean pulmonary artery systolic pressure dropped from 77 mmHg preoperatively to 32 mmHg, and the pulmonary artery mean pressure from 47 mmHg to 17 mmHg, pulmonary wedge pressure from 32 mmHg to 9 mmHg, and pulmonary vascular resistance from 4.74 to 1.8 Wood units. The cardiac index came back to normal in all patients (2.18 vs. 3.0 l/min/m2). Swan-Ganz catheterization was also performed during exercise (work load; 50 Watts in three patients, 100 Watts in six patients). The reaction of the hemodynamic parameters on exercise in most patients was almost normal. CONCLUSION: Our data indicate that in aortic stenosis, even with severe left heart failure, pulmonary hypertension can be fully reversible and a significant improvement in both rest and effort hemodynamic parameters can be expected.

Adult↗
PubMed1993

Effects of leflunomide (HWA 486) on expression of lymphocyte activation markers.

Leflunomide (HWA 486), an isoxazol derivative, has been shown to be very effective in combating autoimmune diseases and transplantation rejection in a great number of animal models. The main metabolite of leflunomide, A77 1726, is a potent antiproliferative compound. To further elucidate this effect, lymphocytes of healthy human donors were cultured for 24, 48 or 72 h in the presence of PHA or immobilized anti-CD3 antibody. A77 1726 was added at concentrations between 10 and 100 microM. Flow cytometric evaluation of early activation or proliferation markers (IL-2 and transferrin receptors, respectively) showed that their expression was inhibited in a dose-dependent manner by A77 1726. Together with previous data, these experiments indicate that leflunomide not only inhibits the expansion of already proliferating lymphocytes, but also impairs PHA and anti-CD3 antibody triggered activation of quiescent cells. Thus, this compound may exert its effects through influencing two important aspects of an immune response, that is, activation and proliferation of lymphocytes.

Adult↗