0000000000299238
AUTHOR
Andreas Rümelin
Ascorbic acid reduces noise-induced nitric oxide production in the guinea pig ear.
Objectives: Noise-induced hearing loss can be caused, among other causes, by increased nitric oxide (NO) production in the inner ear leading to nitroactive stress and cell destruction. Some studies in the literature suggest that the degree of hearing loss (HL) could be reduced in an animal model through ascorbic acid supplementation. To identify the effect of ascorbic acid on tissue-dependent NO content in the inner ear of the guinea pig, we determined the local NO production in the organ of Corti and the lateral wall separately 6 hours after noise exposure. Study Design: Prospective animal study in guinea pigs. Methods: Over a period of 7 days, male guinea pigs were supplied with minimum (…
Determination of α-Tocopherol in Plasma by High Performance Liquid Chromatography with Fluorescence Detection and Stability of α-Tocopherol under Different Conditions
In order to study the clinical effects of the antioxidant alpha-tocopherol (tocofersolan, CAS 30999-06-5) a simple, robust, sensitive and reliable high performance liquid chromatography (HPLC) method using fluorescence detection for the daily measurement of alpha-tocopherol concentration in plasma is described. Several methods of HPLC analysis using fluorescence techniques are published, however, investigations of the stability of alpha-tocopherol during sample preparation under different conditions are relevant in the routine measurements and have to date not been reported. Therefore a modified method, both sensitive and robust, qualified for the day-by-day measurement of alpha-tocopherol …
Metabolic Clearance of the Antioxidant Ascorbic Acid in Surgical Patients1
Background A reduction of plasma ascorbic acid concentration in the post-operative period has been well documented and is associated with an increase in post-operative complications. The underlying reason for the decreased concentration of ascorbic acid in the plasma is not clear. However, only an increased post-operative requirement for ascorbic acid would justify a substitution. Therefore, we investigated the pre-operative and post-operative metabolic clearance of ascorbic acid. Materials and Methods We calculated the metabolic clearance subsequent to intravenous bolus injection of 6 mg ascorbic acid/kg body weight in 15 patients before and after they underwent major maxillofacial surgery…
Early postoperative substitution procedure of the antioxidant ascorbic acid.
Postoperatively reduced concentration of ascorbic acid (AA) in plasma (or =45.5 micromol/l (or =800 microg/dl)) is commonly interpreted as increased metabolic requirements, but it is not shown yet that the patient benefits from a substitution toward normal levels of AA. This is due to the missing knowledge on how to substitute AA effectively to normal plasma values in postoperative patients. Therefore, a postoperative AA substitution procedure "overnight" to normal values in plasma was investigated on a postoperative intensive care unit (ICU) in a university hospital.Fifty-seven operated patients were randomly assigned to a control- or intervention group (CG and IG, respectively). In all pa…
Ascorbic Acid in Postoperative Intensive Care Patients - Biochemical Aspects and Clinical Experience
The transport mechanisms of ascorbic acid (AA) are described. The metabolism of AA and its function as an antioxidant are covered in some detail. Subsequently, indications for postoperative substitution are discussed. The supplementation of up to 300 mg of AA per day in postoperative intensive care unit patients during par-/enteral nutrition is recommended to prevent hypovitaminosis. It is not clear if this is the optimal dosage of AA in postoperative/-trauma patients. New aspects for an AA substitution are discussed.
Ceftazidime Determination in Serum by High-pressure Liquid Chromatography
A rapid and sensitive high-pressure liquid chromatographic method with simple sample preparation was developed for the quantitative analysis of the beta-lactam antibiotic ceftazidime (CAS 78439-06-2, Fortum). A good linear relationship was established between the peak area and the amount of ceftazidime injected over a concentration range of 1 to 200 microg/ml. The detection limit of the method was calculated to be 0.9 microg/ml. Stability was shown at 4 degrees C and at -196 degrees C for time periods of 2 h and 84 days, respectively.
Postoperative analgesic efficacy of peripheral levobupivacaine and ropivacaine: a prospective, randomized double-blind trial in patients after total knee arthroplasty.
BACKGROUND: Several previous trials have characterized the intra- and postoperative effects of the recently introduced local anesthetics, levobupivacaine and ropivacaine, for a variety of continuous peripheral nerve blocks. METHODS: We compared the analgesic efficacy of levobupivacaine 0.125% versus ropivacaine 0.2% via patient-controlled femoral nerve analgesia after total knee arthroplasty. In a double-blind, randomized, prospective design, 60 patients received femoral infusion with either substance. We analyzed postoperative local anesthetic consumption, pain scores, motor block, and opioid requirements over 72 h. RESULTS: Pain scores, motor block incidence, and opioid requirements were …
Determination of ascorbic acid in plasma and urine by high performance liquid chromatography with ultraviolet detection.
Abstract A reliable simple reversed-phase liquid chromatographic method for the routine determination of ascorbic acid in plasma and urine with ultraviolet detection is described. This method enables the complete separation of the ascorbic acid peak from others with a recovery of above 95 % within 8 minutes. The method can be used for analysing multiple samples within a day. In addition, the storage conditions and stability of ascorbic acid in plasma and urine were investigated. Samples of plasma and urine can be stored on ice in darkness for at least 60 min without reduction of ascorbic acid concentration. Prepared samples can be stored in darkness at 4 °C for at least 120 min and in liqui…
Clearance of Ascorbic Acid in Plasma in Patients Before Major Maxillofacial Surgery Compared With That in Volunteers
Reduced concentration of ascorbic acid (AA) in plasma is often observed in tumor patients. Besides malnutrition, an increased AA consumption in tumor patients is discussed as a main reason for reduced AA concentration in plasma. A reduced AA concentration caused by malnutrition would not influence the total clearance (Cltot) of AA in plasma; however, a change in AA consumption would alter the Cltot. To investigate this further, a study was carried out on 20 patients hospitalized for major maxillofacial surgery and 20 volunteers. The Cltot of AA in plasma after bolus injection of AA (4 mg/kg body wt) in tumor patients was compared with that in volunteers. AA concentration in plasma (P0.05) w…