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Biomedical subjects

C Konrad

Publications and source records attributed to C Konrad.

At least 37 records · Page 2Linked to original sources
PubMed2000

Interaction of acetylcholine and endothelin-1 in the modulation of pulmonary arterial pressure.

OBJECTIVE: The study was designed to investigate the effects of acetylcholine (ACh) on pulmonary circulation with special regard to mediators that could be involved in the mediation of ACh-induced effects. ACh has been reported to induce either vasodilation or vasoconstriction in the pulmonary circulation of different species. DESIGN: Prospective experimental study in rabbits. SETTING: Experimental laboratory in a university teaching hospital. SUBJECTS: Sixty-six adult rabbits of either sex. INTERVENTIONS: The experiments were performed on 66 isolated and ventilated rabbit lungs that were perfused with a cell- and plasma-free buffer solution. ACh was injected in various concentrations after pulmonary artery preconstriction and in untreated lungs. MEASUREMENTS AND MAIN RESULTS: Pulmonary arterial pressure (PAP) and lung weight gain were monitored continuously. Perfusate samples were taken intermittently to determine endothelin-1 (ET-1), thromboxane A2 (TXA2), and prostacyclin (PGI2) concentrations. ACh in final dosages from 10(-5) to 10(-2) M (n = 6 each) was injected into the pulmonary artery of lungs treated with U46619 to induce pulmonary arterial hypertension or was injected into untreated lungs. To analyze the potential mechanisms of action, ACh (10(-5) M) was administered in additional experiments after pretreatment with either ETA receptor antagonist BQ123 (10(-6) M; n = 6) or the cyclooxygenase inhibitor diclofenac (10 microg/mL; n = 6). In preconstricted pulmonary vessels, ACh (10(-3) and 10(-2) M) initially induced a PAP rise for 10 mins followed by a sustained decrease. In untreated lungs, ACh induced an immediate dose-dependent increase in PAP, requiring as long as 30 mins to return to predrug levels. Simultaneously, significantly elevated TXA2 and PGI2 levels were observed. Furthermore, ET-1 was detected in the perfusate, which was free from ET-1 before ACh administration. Pretreatment with BQ123 reduced substantially the ACh (10(-5) M)-induced PAP increase and the release of TXA2 and PGI2. At 5 mins, the PAP maximum was reduced from 18.5 +/- 3.2 mm Hg to 9.9 +/- 0.65 mm Hg by BQ123 pretreatment (p < .01). An inhibition of PAP increase was also observed after diclofenac pretreatment (11.6 +/- 0.4 mm Hg at 5 mins; p < .05). Inhibitory effects at 5 mins were significantly more pronounced in the BQ123 group compared with the diclofenac group. CONCLUSIONS: The effects of ACh on the pulmonary circulation of isolated rabbit lungs depend on ACh concentration and the basal tone of the arterial vasculature. In lungs with a normal pulmonary vascular resistance, ACh administration causes vasoconstriction via the release of ET-1 and TXA2, whereas vasodilation is induced in preconstricted pulmonary vessels.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed2000

Roles of transcription factor Mot3 and chromatin in repression of the hypoxic gene ANB1 in yeast.

The hypoxic genes of Saccharomyces cerevisiae are repressed by a complex consisting of the aerobically expressed, sequence-specific DNA-binding protein Rox1 and the Tup1-Ssn6 general repressors. The regulatory region of one well-studied hypoxic gene, ANB1, is comprised of two operators, OpA and OpB, each of which has two strong Rox1 binding sites, yet OpA represses transcription almost 10 times more effectively than OpB. We show here that this difference is due to the presence of a Mot3 binding site in OpA. Mutations in this site reduced OpA repression to OpB levels, and the addition of a Mot3 binding site to OpB enhanced repression. Deletion of the mot3 gene also resulted in reduced repression of ANB1. Repression of two other hypoxic genes in which Mot3 sites were associated with Rox1 sites was reduced in the deletion strain, but other hypoxic genes were unaffected. In addition, the mot3Delta mutation caused a partial derepression of the Mig1-Tup1-Ssn6-repressed SUC2 gene, but not the alpha2-Mcm1-Tup1-Ssn6-repressed STE2 gene. The Mot3 protein was demonstrated to bind to the ANB1 OpA in vitro. Competition experiments indicated that there was no interaction between Rox1 and Mot3, indicating that Mot3 functions either in Tup1-Ssn6 recruitment or directly in repression. A great deal of evidence has accumulated suggesting that the Tup1-Ssn6 complex represses transcription through both nucleosome positioning and a direct interaction with the basal transcriptional machinery. We demonstrate here that under repressed conditions a nucleosome is positioned over the TATA box in the wild-type ANB1 promoter. This nucleosome was absent in cells carrying a rox1, tup1, or mot3 deletion, all of which cause some degree of derepression. Interestingly, however, this positioned nucleosome was also lost in a cell carrying a deletion of the N-terminal coding region of histone H4, yet ANB1 expression remained fully repressed. A similar deletion in the gene for histone H3, which had no effect on repression, had only a minor effect on the positioned nucleosome. These results indicate that the nucleosome phasing on the ANB1 promoter caused by the Rox1-Mot3-Tup1-Ssn6 complex is either completely redundant with a chromatin-independent repression mechanism or, less likely, plays no role in repression at all.

Aerobiosis↗
PubMed1999

Detection of fluid volume absorption by end-tidal alcohol monitoring in patients undergoing endoscopic renal pelvic surgery.

STUDY OBJECTIVE: To determine the risk of relevant fluid absorption (calculated volume above 500 ml) during endoscopic procedures of the renal pelvis. DESIGN: Prospective clinical investigation with implementation of statistical process control tools (SPC). SETTING: Nonuniversity teaching hospital. PATIENTS: 62 consecutive ASA physical status I and II patients scheduled for endoscopic renal pelvic surgery with general anesthesia. INTERVENTIONS: Intraoperative measurement of breath alcohol for detection of fluid absorption. Irrigation fluid (0.9% saline) with 1% alcohol for tracing the irrigation fluid. MEASUREMENTS AND MAIN RESULTS: Calculation of the amount of fluid absorbed using breath alcohol values. Process variability (numbers of patients with relevant fluid absorption) defined by SPC. The prevalence of fluid absorption in endoscopic renal pelvic surgery was 6%. Peak fluid absorption during a vascular route was detected by the monitoring. Monitoring was easily introduced into routine clinical practice. No relevant side effects due to the monitoring were seen in patients with relevant fluid absorption. There was no mortality, but two patients with detected severe fluid overload were admitted to the intensive care unit for treatment. CONCLUSION: Breath alcohol levels during general anesthesia for endoscopic renal pelvic surgery were technically simple to measure. Our results show the predictive value of alcohol monitoring, which has been previously demonstrated only for transurethral prostatectomy. The prevalence of relevant fluid absorption was 6% compared to 13% during transurethral resection of the prostate.

Absorption↗
PubMed1999

The effects of in vitro hemodilution with gelatin, hydroxyethyl starch, and lactated Ringer's solution on markers of coagulation: an analysis using SONOCLOT.

UNLABELLED: Blood-saving strategies have recently been established to avoid allogeneic transfusion during surgery or after trauma. This includes an expanding use of crystalloids and colloids. These solutions interfere with coagulation systems, but quantitative measurements are still lacking. The SONOCLOT (Sienco Company, Morrison, CO) analysis (SCT), a viscoelastic test, measures clot formation and includes information on the cellular, as well as the plasmatic coagulation, system. To quantify hemodilutional effects on in vitro coagulation, we studied gelatin (G), hydroxyethyl starch 6% (HES; molecular weight 450,000), and lactated Ringer's solution (RL) in 33% and 66% dilutions measuring routines laboratory and SCT variables. Hemodilution with RL tended to increase in vitro coagulability. Among the tested colloids, G had the least impact on markers of coagulation. G33% did not differ significantly from the undiluted control group. HES had the largest impact on markers of coagulation compared with G and RL. In conclusion, SCT provides a fast and easy to perform bedside test to quantify in vitro hemodilution. IMPLICATIONS: The effects of progressive hemodilution on coagulation are difficult to measure. SONOCLOT analyses provide an easy to perform test with fast information on cellular and plasmatic coagulation properties. Among colloids, hydroxyethyl starch has the largest impact on markers of coagulation compared with gelatin or lactated Ringer's solution.

Adult↗
PubMed1998

Transurethral resection syndrome: effect of the introduction into clinical practice of a new method for monitoring fluid absorption.

STUDY OBJECTIVE: To determine the effects of introduction of a new monitoring system for fluid absorption during transurethral resection of the prostate (TURP) using an irrigating solution containing 0.5% alcohol. STUDY DESIGN: Prospective clinical investigation, with implementation of statistical process control. SETTING: Inpatients for TURP at a major non-university teaching hospital. PATIENTS: 312 male ASA physical status I, II, III, and IV patients scheduled for TURP. INTERVENTIONS: Intraoperative breath alcohol levels were measured for detection of fluid absorption. MEASUREMENTS AND MAIN RESULTS: Calculation of the amount of fluid absorbed using measured breath alcohol values. Process variability (i.e., numbers of patients with significant fluid absorption) was defined by statistical process control tools. No trend change of prevalence of fluid absorption was noted until 150 procedures had been completed. Reduction of prevalence of significant fluid absorption was noted and no patients were treated postoperatively in the intensive care unit. No relevant side effects were seen in patients with significant fluid absorption. No mortality and no severe clinical morbidity was seen after the introduction of the new monitoring. CONCLUSION: Using an irrigating fluid marked with 0.5% ethanol resulted in a decreased prevalence of fluid absorption over time.

Absorption↗
PubMed1998

[Insulin as an anabolic: hypoglycemia in the bodybuilding world].

Excessive body building may be dangerous. To promote athletic performance and to improve physical appearance many of the body builders abuse anabolic-androgenic steroids and other drugs. The abuse of insulin as an anabolic medication in this athletic community was followed by a case of severe hypoglycaemia in a body builder. A 30-year old male presented with cerebral symptoms of hypoglycaemia. Directly before an international competition he tried to stimulate muscle growth by using the hypoglycaemic stimulus to the growth hormone. To achieve this he injected 70 IE of a short-acting insulin subcutaneously, resulting in severe hypoglycaemia. After the initial administration of intravenous glucose by the paramedics, he lost consciousness and showed signs of convulsions. After orotracheal intubation by an emergency physician, despite of ongoing infusion of glucose the blood glucose concentration remained low as measured in the out-of-hospital setting. Finally administration of additional glucose and glucagon in the intensive care unit was able to stabilize the metabolic system. In any case of severe hypoglycaemia, repetitive measurements of blood glucose even in the prehospital setting should be performed to detect the hypoglycaemia especially if athletes are concerned.

Adult↗
PubMed1998

Learning manual skills in anesthesiology: Is there a recommended number of cases for anesthetic procedures?

UNLABELLED: The learning process is a multidimensional function with a wide intra- and interindividual scattering. To determine the learning process in anesthesia, we evaluated 11 first-year residents according to their rate of success or failure when applying manual anesthesiological skills, such as performance of spinal, epidural, or brachial plexus anesthesia and tracheal intubation or insertion of an arterial line. Epidural anesthesia was the most difficult procedure (P < 0.05). Significant differences were found between epidural anesthesia and tracheal intubation (P < 0.05), insertion of an arterial line (P < 0.05), and brachial plexus block (P < 0.05), as well as between spinal anesthesia and orotracheal intubation (P < 0.05). Learning curves are a valid tool for monitoring institutional and individual success. IMPLICATIONS: To investigate the learning process in anesthesia, typical anesthetic procedures were performed by inexperienced residents during their first year. Learning curves were generated for each procedure performed. Epidural anesthesia was the most difficult procedure to perform (P < 0.05).

Anesthesia, Epidural↗
PubMed1998

Blockade of the sciatic nerve in the popliteal fossa: a system for standardization in children.

UNLABELLED: The sciatic nerve can be blocked at different levels, providing excellent surgical and postoperative anesthesia and analgesia. We report a series of 50 blocks performed via the popliteal fossa in children. Localization of either the tibial or peroneal nerve was facilitated by a nerve stimulator. The local anesthetic solution was injected at the point where nerve stimulation was achieved with 0.4 mA at an impulse width of 1.0 ms. The depth of insertion of the stimulation cannula correlated with the age, weight, and height of the patients. The best predictor for depth of insertion was the patient's weight. The minimal depth of insertion was 13 mm. No failure of blockade was seen in this case series. Blockade of the sciatic nerve can easily be performed in the popliteal fossa even in small children. IMPLICATIONS: Blockade of the sciatic nerve can easily be performed in the popliteal fossa even in small children. The depth of insertion of the stimulation cannula can best be estimated according to the weight of the patient. The minimal depth required was 13 mm.

Adolescent↗
PubMed1998

Comparing the enzyme allergosorbens and coated allergen particle tests for latex allergy: which in vitro test should be chosen by an anesthesiologist?

UNLABELLED: To determine sensitivity and specificity of the enzyme allergosorbens test (EAST) and the coated allergen particle Test (CAP) in detecting specific antibodies against latex, we compared these two methods in a previously investigated sample of an epidemiological study among our anesthesia staff. One hundred one blood samples were tested with EAST and CAP for specific antibodies against latex. Skin test results were used as references. CAP was more sensitive in detecting sensitized individuals than EAST (56% vs 18.8%). Two additional persons with previously negative skin tests were detected. These results suggest that the EAST system is not as sensitive as the CAP system. Therefore, the CAP system should be preferred for the in vitro diagnosis of latex allergy. IMPLICATIONS: Testing for latex allergy requires time-consuming and technically difficult tests. Easy to perform in vitro tests for latex allergy are desirable. Our results indicate that the coated allergen particle test is more sensitive and easy to use than the enzyme allergosorbens test.

Anesthesiology↗
PubMed1997

[Oxygen embolism after use of hydrogen peroxide in thoracic surgery].

UNLABELLED: Hydrogen peroxide is often used for irrigation of surgical wounds. In the presented two cases hydrogen peroxide was used to irrigate the thoracic cavity after thoracotomy for lung surgery. After irrigation with hydrogen peroxide only one patient showed clinical signs of pulmonary embolism. In both cases the postoperative recovery was uneventful. In one of the cases transesophageal echocardiography showed air bubbles, a sign of oxygen embolism, passing the right heart. CONCLUSION: The application of hydrogen peroxide in preformed cavities, such as the thoracic, should be avoided.

Echocardiography↗
PubMed1997

Is an alkalinized lignocaine solution a better topical anaesthetic for intratracheal application?

Topical anaesthesia of the trachea is used to avoid coughing during emergence from anaesthesia. This study was designed to compare the effects of an alkalinized lignocaine and plain lignocaine solution given intratracheally. After institutional approval and written informed consent, 30 patients were randomized into three groups and received in a double-blind fashion: lignocaine, alkalinized lignocaine and normal saline for control. After application of normal or alkalinized lignocaine the tolerance to the tube was significantly better during extubation (P = 0.001). Noradrenaline levels were significantly diminished in the lignocaine groups (P < 0.05). Plain and alkalinized lignocaine solutions for topical anaesthesia significantly improved tolerance to the tracheal tube during emergence from anaesthesia. Plain and alkalinized lignocaine given directly before intubation reduced the sympathomimetic stress response resulting in a lower noradrenaline concentration and a reduced heart rate.

Adolescent↗
PubMed1997

The prevalence of latex sensitivity among anesthesiology staff.

Reports dealing with allergic reactions to latex among health care professionals are increasing steadily. This study is the first epidemiological investigation of latex allergy among anesthesia staff. We tested 101 persons of the staff of the Institute of Anesthesiology, Kantonsspital, Lucerne, Switzerland, using a standardized questionnaire, prick test (latex extract), scratch test (latex glove), and immunoglobin E (IgE) analysis. Sixteen of 101 persons (15.8%) had a positive skin test. Two of them had a positive radioallergosorbent test (RAST) Class II, and one person was Class I. Risk factors were a history of atopy (P < 0.001) and positive skin tests on atopy screening (P = 0.016). IgE levels were increased in the latex-sensitive group. Three of the 11 sensitized persons (total sensitized persons 16) who performed spirometry had significantly reduced expiratory peak flow values during working hours. It is concluded that anesthesiology staff is at high risk of allergic sensitization to latex. The most important risk indicator was an atopy. Skin tests are more sensitive than blood tests (i.e., specific antibodies, IgE).

Adult↗
PubMed1997

[Risperidone after clozapine in therapy refractory schizoaffective psychosis--a case report].

Recently, American authors pronounced the hypothesis that Clozapine-response may be considered as a predictor of response to atypical neuroleptic. We report the history of a schizoaffektive patient unresponsive to butyrophenone and phenothiazine neuroleptic who was first treated with Clozapine and then with Risperidone and who reacted very differently to these atypical neuroleptic.

Adult↗
PubMed1996

[Electronic expert system in medicine. For example ILIAD].

Expert systems are knowledge data bases founded on patient data, literature searches and opinions of experts. With these systems it is for instance possible to test or to take clinical decisions. ILIAD, USA version 4.2, an adaptable software using probabilistic strategies, was investigated. This system is, among other uses, employed for quality assurance and documentation, as a teaching instrument as well as a knowledge base. It comprises the ICD-9 index of diagnoses and a selected and commented up-to-date review of the literature from 'Mosby's Year Book of Medicine'. The features of ILIAD are presented, and the possibilities and limitations of its use as well as that of expert systems in general are discussed.

Diagnosis, Computer-Assisted↗
PubMed1996

[Latex allergy--not only a threatening danger to patients. A case report from an anesthesiological department].

A 31-old male nurse of anesthesiology was exposed to rubber gloves over a period of ten years. An atopic diathesis was known. From time to time he had episodes of pollinosis. Since nine months he had suffered from conjunctivitis, rhinitis and shortness of breath while wearing latex gloves. During a night shift ten minutes after consumption of tropical fruit (bananas, kiwi) he had to care for a patient in the emergency room. He wore rubber gloves and had to clean the emergency room. Initially, his palms and feet itched. Then he experienced angor and increased perspiration 90 seconds later he suffered severe dyspnea and dysesthesia in the lower extremities. Treatment with theophylline and beta sympathomimetics, steroids and antihistaminics was successful. This male nurse had a positive history for contact urticaria after exposition to rubber. He suffered a dramatic exacerbation when wearing latex gloves and inhaling latex-contaminated air after eating tropical fruits. Fruit could have been a potent booster. Hospital employees with a history of atopic disease should be screened for potential latex allergy before occupational exposure.

Adult↗