Search PubMed⌕ Search

Biomedical subjects

F Lackner

Publications and source records attributed to F Lackner.

At least 19 recordsLinked to original sources
PubMed2005

An international collaborative study to replace the 1st international standard for prekallikrein activator.

BACKGROUND AND OBJECTIVES: The aim of this study was to replace the 1st International Standard (IS) for prekallikrein activator (PKA) (code 82/530) with a new IS and European Biological Reference Preparation (BRP). The new standards were freeze dried 20% albumin solution containing PKA, the same solution that is tested using these standards. Aspects of the methodology for PKA determination were also examined as part of this study. MATERIALS AND METHODS: A batch of 20% albumin containing approximately 30 IU/ml was donated by a manufacturer of blood products and dispensed into ampoules at the National Institute for Biological Standards and Control (NIBSC) to create the candidate IS (02/168, sample B in the study) and at the European Directorate for the Quality of Medicines (EDQM) to create the candidate BRP (sample C in the study). The concentration of PKA in these preparations was determined in an international collaborative study involving 31 laboratories from 17 countries worldwide in comparison with the 1st IS for PKA (82/530) containing 85 IU of PKA per ampoule. Participants were requested to perform their own in-house method, based on the current Ph. Eur. monograph for determination of PKA in albumin solutions. Participants were provided with sufficient samples to perform two or three assays and were asked to use their local prekallikrein substrate (PKS) and also to use a commercial PKS provided as part of the study, in order to investigate the importance of the source of PKS on the final potency values. RESULTS: Samples B and C emerged with identical PKA concentrations of 29 IU/ml, very close to the expected value. This figure was determined using a variety of statistical methods, with the participants' own calculated values and values calculated centrally at the EDQM using raw data. The value of 29 IU/ml was consistent and independent of the method of calculation, although interlaboratory variability was more sensitive to the statistical analysis method. There was no statistically significant difference in mean potencies when comparing results with the laboratories' own local substrate and the substrate provided for the study. All stability studies indicate that these lyophilized preparations of PKA in 20% albumin are extremely stable. CONCLUSIONS: Samples B and C were established as the 2nd IS (code 02/168) and PKA activator in albumin BRP batch 1 (Y0000263), respectively, with a potency of 29 IU per ampoule. Results from this study indicate that testing for PKA in albumin may be less sensitive to the source of PKS than previously feared. The study highlights a number of methodological issues that may need revising in the Ph. Eur. general chapter 2.6.15.

Cooperative Behavior↗
PubMed2005

Collaborative study to establish a new biological reference preparation for prekallikrein activator.

An International Collaborative Study was organized to replace the current World Health Organization (WHO) International Standard (IS) for Prekallikrein Activator (PKA) and to establish a European Pharmacopoeia (Ph. Eur.) Biological Reference Preparation (BRP). The project was jointly organized by the European Directorate for the Quality of Medicines (EDQM) and the National Institute for Biological Standards and Control (NIBSC) to identify and calibrate suitable materials that could act as an IS and a Ph. Eur. BRP. The current IS for PKA (82/530) is popular and stocks are declining rapidly, therefore necessitating calibration of a replacement. A Ph. Eur. BRP is needed, as PKA control on the finished product is part of the Official Control Authority Batch Release (OCABR) of Human Albumin. The current IS, 82/530 is a 5 per cent albumin solution spiked with purified PKA. However, during planning stages it was decided that the replacement IS (and BRP) should be made from a 20 per cent albumin preparation containing a significant level of PKA as the current IS is used to measure PKA in albumin and high levels are more likely to be encountered in more concentrated 20 per cent solutions. A suitable material was sourced by the EDQM and filled into ampoules at NIBSC and vials by the EDQM. Both preparations were included in the collaborative study that involved 31 laboratories from 17 countries. Another important goal of this study was to investigate the influence of the prekallikrein substrate (PKS) on PKA determination in albumin solutions following earlier concerns that variability amongst PKS prepared in-house could significantly affect PKA determinations. Laboratories were requested to perform their routine assays following Ph. Eur. guidelines and recommendations on doses, replication and randomization were also provided to study participants. Participants were requested to use material A (the current IS, 82/530) to perform at least 4 assays to determine PKA levels in sample B (NIBSC ampouled material, candidate IS, 02/168), sample C (EDQM material in vials candidate Ph. Eur. BRP Batch 1), and sample D (an ampouled preparation of 2.5 per cent albumin containing a lower level of PKA). A commercial substrate was provided for participants to perform half the assays and the remaining assays were to be performed using the laboratories' in-house substrate (where available). Collation of participants' results showed that samples B and C had the same level of PKA of 29 IU/ampoule, the concentration anticipated from development studies. Importantly, there was no significant difference between the PKA level obtained using the commercial substrate provided and the laboratories' own in-house substrate. Previous observations on lyophilized preparations of PKA indicate that the enzyme is very stable. Detailed investigations conducted in this study show that the PKA in albumin used to make samples B and C is very stable and suitable for long-term storage as a reference material.

Factor XIIa↗
PubMed1997

Mild intraoperative hypothermia prolongs postanesthetic recovery.

BACKGROUND: Intraoperative hypothermia is common and persists for several hours after surgery. Hypothermia may prolong immediate recovery by augmenting anesthetic potency, delaying drug metabolism, producing hemodynamic instability, or depressing cognitive function. Accordingly, the authors tested the hypothesis that intraoperative hypothermia prolongs postoperative recovery. METHODS: Patients undergoing elective major abdominal surgery (n = 150) were anesthetized with isoflurane, nitrous oxide, and fentanyl. They were randomly assigned to routine thermal management (hypothermia) or extra warming (normothermia). Postoperative surgical pain was treated with patient-controlled analgesia. Fitness for discharge from the postanesthesia care unit was evaluated at 20-min intervals by investigators blinded to group assignment and postoperative core temperatures. Scoring was based on a modification of a previously published system that included activity, ventilation, consciousness, and hemodynamic responses. Patients were considered fit for discharge when they sustained a score of 80% (13 points) for at least two consecutive measurement periods. RESULTS: Morphometric characteristics and anesthetic management were similar in each group. Final intraoperative core temperatures differed by approximately 2 degrees C: 34.8 +/- 0.6 versus 36.7 +/- 0.6 degrees C (mean +/- SD, P < 0.001). Postoperative pain scores and postoperative use of patient-controlled opioid were similar. Hypothermic patients required approximately 40 min longer (94 +/- 65 vs. 53 +/- 36 min) to reach fitness for discharge, even when return to normothermia was not a criterion (P < 0.001). Duration of recovery in the two groups differed by approximately 90 min when a core temperature >36 degrees C was also required (P < 0.001). CONCLUSION: Maintaining core normothermia decreases the duration of postanesthetic recovery and may, therefore, reduce costs of care.

Abdomen↗
PubMed1995

The influence of proteins on silver staining of nucleic acids following polyacrylamide gel electrophoresis.

The influence, on silver staining, of proteins and restriction enzymes in polymerase chain reaction (PCR) products was studied in 12-20% polyacrylamide gels. For small DNA fragments (74, 41 and 33 bp) best results were achieved using 20% polyacrylamide gels. In 12% gels, restriction enzymes and also proteins used for PCR (bovine serum albumin, Taq-DNA polymerase) interfere with silver staining of nucleic acids.

DNA↗
PubMed1995

Postoperative hemodynamic and thermoregulatory consequences of intraoperative core hypothermia.

STUDY OBJECTIVE: To evaluate the postoperative hemodynamic and thermoregulatory consequences of intraoperative core hypothermia. DESIGN: Prospective, randomized clinical trial. SETTING: Operating room and postanesthesia care unit of a university hospital. PATIENTS: 74 healthy, ASA status I, II, and III patients (average age 58 yrs) undergoing elective colon surgery. INTERVENTIONS: Patients were randomly assigned to be kept normothermic or approximately 2.5 degrees C hypothermic during surgery. Anesthesia was maintained with isoflurane, nitrous oxide, and fentanyl. Postoperatively, surgical pain was treated with patient-controlled analgesia (PCA) opioid. MEASUREMENTS AND MAIN RESULTS: An observer blinded to group assignment and core temperatures evaluated shivering, thermal comfort, surgical pain, heart rates (HRs), and blood pressures (BPs) during the first six postoperative hours. Morphometric characteristics, oxygen saturation, fluid balance, PCA-administered opioid, and visual analog pain scores were comparable in the two groups. Hypothermic patients felt uncomfortably cold during recovery, and their postoperative core temperatures remained significantly less than in the normothermic patients for more than four hours. Peripheral vasoconstriction and shivering were common in the hypothermic patients but rare in those kept normothermic. HRs and BPs were comparable in the two groups. CONCLUSIONS: These data confirm that the effects of intraoperative hypothermia on postoperative HR and BP are modest in relatively young, generally healthy patients. In contrast, intraoperative hypothermia caused substantial postoperative thermal discomfort, and full recovery from hypothermia required many hours. Delayed return to care normothermia apparently resulted largely from postoperative thermoregulatory impairment.

Analgesia, Patient-Controlled↗
PubMed1995

Pharmacodynamics, pharmacokinetics, and intubation conditions after priming with three different doses of vecuronium.

The effects of three different priming doses of vecuronium on pharmacokinetics, pharmacodynamics, and endotracheal intubation conditions were investigated. Forty-two patients were studied in two parts. In each part, 21 patients were allocated into three groups (n = 7/group) receiving 10, 15, or 20 micrograms/kg vecuronium as a priming dose, followed by a 50- micrograms/kg intubating dose 6 min later. In Part I, Train-of-Four (TOF) ratios and serum concentrations after priming were measured every minute up to the sixth minute. Onset time [from injection of the intubating dose to maximum depression of the first twitch (T1)], clinical duration (T1 return from maximum block to 25% of control), and recovery index (T1 recovery from 25% to 75% of control) were calculated and serum concentrations were determined up to 6 h after injection of the intubating dose. In Part II, the intubating dose was injected 4 min after priming, onset time was determined, and intubation conditions were scored. TOF ratio was significantly lower after priming with 20 micrograms/kg at the fifth and sixth minutes (0.59 +/- 0.29 and 0.56 +/- 0.32; mean +/- 1 SD) compared with the first minute (0.95 +/- 0.1). Recovery index was significantly increased after priming with 20 micrograms/kg (13.2 +/- 6.6 min, P < 0.05) compared with 10 micrograms/kg (9.2 +/- 4.8 min) and 15 micrograms/kg (6.7 +/- 1.5 min). Between groups no differences in onset time, clinical duration, and pharmacokinetic variables were found. In Part II, onset time and intubating scores showed no significant differences between the groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Morphometric influences on intraoperative core temperature changes.

Intraoperative core hypothermia develops in three characteristic phases: 1) core-to-peripheral redistribution of body heat that is most prominent during the first hour after induction of anesthesia; 2) subsequent slow linear decrease in core temperature resulting largely from heat loss exceeding metabolic heat production; and 3) core temperature plateau resulting when thermoregulatory vasoconstriction decreases cutaneous heat loss and constrains metabolic heat to the core thermal compartment. Accordingly, we tested the hypotheses that: 1) core cooling does not depend on body fat (BF) or the ratio of weight-to-surface area (Wt/SA) during the initial redistribution phase; 2) the core cooling phase; 2) the core cooling rate is a function of the Wt/SA ratio during the second phase; and 3) the rate of core cooling during the plateau phase (after vasoconstriction) will be determined by the percentage of BF. In 40 patients undergoing elective colon surgery, the amount of redistribution hypothermia was inversely proportional to the percentage of BF (delta TC = 0.034.BF-2.2, r2 = 0.63) and the Wt/SA ratio (delta TC = 0.052.Wt/SA-3.35, r2 = 0.66). The core cooled linearly during the second phase, and the cooling rate was inversely proportional to the Wt/SA ratio (rate = 0.035.(Wt/SA)-2.2, r2 = 0.29). Thermoregulatory vasoconstriction was effective in virtually all patients independent of their morphology, and produced a four-fold reduction in the core cooling rate. These results indicate that patient morphometric characteristics substantially influence intraoperative core temperature changes, and that the effect depends on the hypothermia phase.

Adult↗
PubMed1994

[The critical care patient in the operating room].

ICU patients can undergo elective or emergency surgery. Optimising the patient and arranging for the necessary blood components is as important as the fully monitored transport to the OR. Monitoring usually includes radial artery and vena cava access routes, pulmonary artery catheters help to check on oxygen transport parameters and cardiac output. Echocardiography is a new feature to determine cardiac volumes and left ventricular function as well as possible regional ischaemia. Anaesthesia induction can be performed using thiopentone along with diazepam and opioids. In shocked patients ketamine helps to prevent further drop of blood pressure. Propofol can also be employed for maintenance of anaesthesia. For muscle relaxation succinylcholine is the agent of choice if crush intubation is necessary. Atracurium and vecuronium should be used according to their specific route of elimination, although there can be interaction with antibiotics or adrenergic blockers. To ventilate the patient a mixture of oxygen in air might be useful, since nitrous oxide might be determined to blood cell formation and may distend gas-containing cavities. With the aid of positive end expiratory pressure FiO2 should be kept at a minimum, respiratory rate and inspiratory-expiratory ratio can keep ventilation pressures within an acceptable range and ensure CO2 excretion. Volume losses will be replaced mainly with Ringer's lactate, of which it takes four times the amount of colloidal replacement solutions which have the side effects of blood-borne infection and anaphylaxis. Fresh frozen plasma, platelets and erythrocytes might be necessary if coagulation parameters or oxygen transportation warrant it.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, General↗
PubMed1994

[Laparoscopic cholecystectomy as a suitable procedure for patients with cardiopulmonary risk factors?].

There is considerable debate whether or not the laparoscopic technique for cholecystectomy supersedes conventional procedures in patients with pre-existing cardiopulmonary disease. Hemodynamic stress and CO2 absorption from the peritoneum can have a negative effect on intraoperative safety. On the other hand, a more rapid recovery of lung function and a shorter stay in hospital are the obvious advantages. 74 patients were investigated in our study: 54 with a low cardiopulmonary risk (group 1, ASA classes I or II) and 20 high risk patients belonging to ASA class III (group 2). Series of blood-gas samples were drawn from an arterial catheter and the respiratory parameters and blood gas values measured before and at the end of the CO2-insufflation period were compared. No dangerous rise in paCO2 or decrease in pH occurred with the ventilation method used in this study (Ti:Te = 1:1, PEEP = 5 mbar, Rf = 10/min modification of the tidal-volume according to the measured paCO2 and ventilation with an O2/air mixture). No significant changes in arterial O2 saturation compared with baseline values occurred and values remained within the physiological range. We conclude that excessive intraoperative paCO2 increase can be avoided by modification of the ventilation procedure and that laparoscopic cholecystectomy is an advantageous technique in the patient with cardiopulmonary disease.

Adult↗
PubMed1993

The threshold for thermoregulatory vasoconstriction during nitrous oxide/isoflurane anesthesia is lower in elderly than in young patients.

BACKGROUND: Thermoregulatory vasoconstriction minimizes further core hypothermia during anesthesia. Elderly patients become more hypothermic during surgery than do younger patients, and take longer to rewarm postoperatively. These data indicate that perianesthetic thermoregulatory responses may be especially impaired in the elderly. Accordingly, the authors tested the hypothesis that the thermoregulatory threshold for vasoconstriction during nitrous oxide/isoflurane anesthesia is reduced more in elderly than in young patients. METHODS: The authors studied 12 young patients aged 30-50 yr and 12 elderly patients aged 60-80 yr. All were undergoing major orthopedic or open abdominal surgery. Anesthesia was induced with thiopental and fentanyl, and maintained only with nitrous oxide (70%) and isoflurane (0.6-0.8%). Core temperature was measured in the distal esophagus. Fingertip vasoconstriction was evaluated using forearm minus fingertip, skin-temperature gradients. A gradient of 4 degrees C identified significant vasoconstriction, and the core temperature triggering vasoconstriction identified the thermoregulatory threshold. RESULTS: The vasoconstriction threshold was significantly less in the elderly patients (33.9 +/- 0.6 degree C) than in the younger ones (35.1 +/- 0.3 degrees C) (P < 0.01). The gender distribution, weight, and height of the elderly and young patients did not differ significantly. The end-tidal isoflurane concentration at the time of vasoconstriction did not differ significantly in the two groups. CONCLUSIONS: These data indicate that thermoregulatory responses in the elderly are initiated at temperatures approximately 1.2 degrees C less than that in younger patients. Thus, it is likely that elderly surgical patients become more hypothermic than do younger patients, at least in part, because they fail to trigger protective thermoregulatory responses.

Adult↗
PubMed1990

Discrimination between antibodies to HIV-1 and HIV-2 in sera from northern Zaire.

136 selected sera from Northern Zaire were screened for antibodies against HIV-1 and HIV-2 using the ELISA method. Reactive sera were confirmed with commercially available Western Blots and additional tests. A data base was used for evaluation of the results. The sera were collected in the town Isiro and in remote rural areas. 36 sera were reactive in the HIV-1 ELISA (ELAVIA-1), 19 of them were confirmed in the HIV-1 Western Blot (Biorad). 21 sera were reactive in the HIV-2 ELISA, but they were not confirmed as HIV-2-specific in three HIV-2 Western Blots (Diagnostics Pasteur, Biorad, Paul-Ehrlich-Institut).

Blotting, Western↗
PubMed1990

[Plasma proteins in the early postoperative course after liver transplantation].

The levels of fibronectin, alpha-1 antitrypsin, and fibrinogen have been studied in 34 patients after orthotopic liver transplantation (OLT). Patients were grouped according to A: postoperative course without complications (n = 18), B: development of sepsis accompanied by organ insufficiency (n = 8), and C: acute rejection (n = 6). The plasma levels of alpha-1 antitrypsin and fibrinogen did not show a typical pattern with respect to the postoperative course. The levels of fibronectin, however, did respond to the postoperative events. Starting from a subnormal level a significant increase was observed in group A (p less than 0.005) and C (p less than 0.05) whereas in group B plasma levels remained low. Significant differences (p less than 0.05) were found on day 3 and 5 between group A and C and group B and C. At the end of the observation period survivors (group A and C) had significantly higher levels of fibronectin than nonsurvivors (group B). Therefore fibronectin might aid to diagnose immunologic disturbances after OLT.

Adult↗
PubMed1990

[The intraoperative use of falipamil (AQ-A39), a new calcium antagonist with specific bradytropic properties].

Tachycardia caused by surgical stimulation can compromise the myocardial oxygen balance and may also lead to a reduction of cardiac output. Conventional drugs with negative chronotropic effects also cause reduction of inotropy. Recent so-called specific bradytropic agents are expected to act merely upon chronotropy without affecting pressure of the systemic or coronary circulation. The goal of this study was to investigate the effects of a calcium channel blocker. Falipamil, on the circulation controlling excessive intraoperative tachycardia. PATIENTS AND METHODS. In this study 15 patients, aged 32 to 73 years, mean 55 +/- 12 were investigated. The cardiac risk classes included classification I-III, according to Goldman. The patients underwent major abdominal or thoracoabdominal operations. Monitoring consisted of a radial arterial cannula, as well as a 7 French Swan-Ganz catheter, which was introduced via the internal jugular vein. Determination of cardiac output was done using the thermodilution technique with a Kimray Medical Association Oklahoma City model 3500; related indexes were calculated. Electrophysiological data were read from the ECG. The recorded QT interval was corrected for heart rate according to the formula of Hegglin and Holzmann. Anesthesia consisted of premedication with diazepam, 0.1 mg/kg, 1 h preoperatively. Anesthesia was induced with thiopentone, 5 mg/kg, and fentanyl, 1.5 micrograms/kg. After giving 1 mg alcuronium, succinylcholine, 1 mg/kg, was used for intubation. Anesthesia was continued using ventilation with O2: N2O 1:2 and intermittent doses of fentanyl and alcuronium. When tachycardia occurred at a rate higher than 100 beats per minute, a dose of 2 micrograms/kg fentanyl was administered to deepen the anesthesia. If this had no influence, control readings were taken and subsequently falipamil 2 mg/kg was injected. After that the hemodynamic parameters were monitored for 1, 2, 3, 5, 10, and 20 min. Statistical analysis was performed using the analyses of variance, followed by the Newman-Keuls test. The level of significance was p less than 0.05. RESULTS. The means and standard deviations of the hemodynamic parameters following induction of anesthesia (0) and at the peak rate are shown in Table 1. The mean increase in heart rate at that time was 38 +/- 18% and the QT and RR interval were reduced concomitantly. Both times the QT measured and the QT corrected for rate did not significantly differ from each other. (ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1989

Esophageal tracheal combitube, endotracheal airway, and mask: comparison of ventilatory pressure curves.

The esophageal tracheal Combitube (ETC) is a new airway especially designed for airway maintenance and ventilation in unconscious patients such as those requiring CPR. The ETC may be used as an esophageal obturator or an endotracheal airway. Previous studies yielded a significantly higher mean arterial oxygen tension (PaO2) during ventilation using an ETC in the esophageal position compared to a conventional endotracheal airway (ETA). To investigate this phenomenon, endotracheal and airway opening pressures were examined in 12 patients in randomized order during ventilation with an ETC in the esophageal position, with an ETA, and with a mask, respectively. In this study again the PaO2 was higher with ETC compared to ETA. The following differences in intratracheal pressure and flow could be found for ETC when compared to ETA: smaller rising pressure during inspiration, prolonged expiratory flow time, and formation of a small positive end expiratory pressure (PEEP). These factors may be responsible for the improved oxygen tension with ETC. Comparing mask to ETC ventilation, PaO2 did not differ; however, mean arterial carbon dioxide tension was higher during mask ventilation.

Adult↗
PubMed1989

[Monitoring infection at the intensive care unit--a multicenter pilot study].

During a period of 3 months an infection survey was carried out in 4 intensive care units (ICUs), 2 in Vienna, Austria, and one each in Ulm and Münster, Federal Republic of Germany, using a common protocol. A total of 329 patients was monitored prospectively. This pilot study was performed to evaluate the usefulness of parameters included in the monitoring form. It was attempted to characterize the patient populations of the four units. Mean duration of stay (1-12 days), mortality (8-26%), leading diagnosis upon admission, intubation rate (41-91%) and use of pulmonary artery catheter (12-35%) were distinctly different. The rate of patients admitted already with an infection was 9-43%, septicemia was diagnosed in up to 27% of the diseased. The rate of infection acquired in the unit was between 12 and 37%, the most frequent types were bronchopneumonia, septicemia and urinary tract infection. When septicemia patients were compared to non-septicemia patients who had been admitted for more than 3 days, it appeared that the latter stayed significantly shorter at the ICU and showed less frequently bronchopneumonia or urinary tract infection at the time of admission. Septicemia patients acquired more frequently additional infections like broncho-pneumonia or urinary tract infection while staying at the ICU. The median day of onset of septicemia was the fifth day and only in a quarter of cases diagnosis could be supported by a positive blood culture. The use of antibiotics in the 4 ICUs is compared and shows marked differences. Based upon experience with this type of infection survey a new modified protocol is introduced, which displays the time course of documented events.

Anti-Bacterial Agents↗
PubMed1988

Hypothermia in Hodgkin's disease after exploratory laparotomy.

Hypothermia is a rare complication of unknown origin in Hodgkin's disease which has been reported after the administration of antineoplastic agents, chlorpromazine and paracetamol. We report a highly febrile patient with stage IV-B Hodgkin's disease of mixed cellularity type who underwent exploratory laparotomy. Because of suspected septic shock high-dose prednisolone was given during surgery. Postoperatively the patient's body temperature fell progressively to 32.9 degrees C and remained at less then 35.5 degrees C for the following 5 days. There seems to be some functional disorder of thermoregulation in Hodgkin's disease. Physical factors during surgery or certain drugs, especially cytotoxics, corticosteroids, anesthetics or antipyretics may lead to prolonged hypothermia.

Body Temperature Regulation↗