Determination of ascorbic acid in plasma and urine by high performance liquid chromatography with ultraviolet detection.

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 degrees C for at least 120 min and in liquid nitrogen for 42 days.

High acceleration impulsive rotations reveal severe long-term deficits of the horizontal vestibulo-ocular reflex in the guinea pig.

While there is agreement that unilateral vestibular deafferentation (UVD) invariably produces an immediate severe horizontal vestibulo-ocular reflex (HVOR) deficit, there is disagreement about whether or not this deficit recovers and, if so, whether it recovers fully or only partly. We suspected that this disagreement might mainly be due to experimental factors, such as the species studied, the means chosen to carry out the UVD, or the nature of the test stimulus used. Our aim was to sort out some of these factors. To do this, we studied the HVOR of alert guinea pigs in response to low and high acceleration sinusoidal and high acceleration impulses after UVD by either labyrinthectomy or by vestibular neurectomy. The HVOR in response to high acceleration impulsive yaw rotations was measured before, and at various times after, either unilateral labyrinthectomy or superior vestibular neurectomy. Following UVD, there was a severe impairment of the HVOR for ipsilesional rotations and a slight impairment for contralesional rotations, after either operation. This asymmetrical HVOR deficit in the guinea pig parallels the deficit observed in humans. Between the first measurement, which was made 1 week after UVD, and the last, which was made 3 months after UVD, there was no change in the HVOR. This lack of recovery was the same after labyrinthectomy as after vestibular neurectomy. The HVOR to low and high acceleration sinusoidal yaw rotations were measured after UVD, and the results were compared with those in response to impulsive rotations. For low acceleration sinusoidal rotations (250 degrees/s2), the gain was symmetrical, although reduced bilaterally. As the peak head acceleration increased, the HVOR became increasingly asymmetric. The HVOR asymmetry for sinusoidal rotations was significantly less than for impulsive rotations that had the same high peak head acceleration (2500 degrees/s2). Our results show that the HVOR deficit after UVD is the same in guinea pigs as in humans; that it is the same after vestibular neurectomy as after labyrinthectomy; that it is lasting and severe in response to high acceleration rotations; and, that it is more obvious in response to impulses than to sinusoids.

The measurement of enzyme activities in the resting human polymorphonuclear leukocyte--critical estimate of a method.

As a system for study, the isolated human polymorphonuclear leukocyte combines the advantages of a quasi-non-invasive preparation with a nearly complete complement of enzymes of carbohydrate and energy metabolism. However, small sample volumes and, in some cases, very low enzyme activities make high demands on sample processing, storage, and performance of continuous measurements, if the enzyme activities are to be measured with acceptable reproducibility. In the presented study several aspects of homogenization, storage, and continuous measurement were scrutinized, to identify critical steps and consider ways of optimizing the method. Polymorphonuclear leukocytes were separated from the blood of healthy subjects by sedimentation and density gradient centrifugation. After ultrasonic homogenization, 13 enzymes of glycolysis and gluconeogenesis, the tricarboxylic acid cycle, and glycogen metabolism were determined photometrically. The variation of several conditions showed: 1. The duration of exposure to ultrasound for the homogenization of polymorphonuclear leukocytes has no influence over a wide range of time. 2. Addition of the detergents Triton X-100 and deoxycholic acid, as well as the SH-group protector dithiothreitol, to the homogenizing medium increased the measured activities of only a few enzymes. 3. Considerable inaccuracy was encountered when the suspension was divided into parts for homogenization with different additives; such splitting of the suspension should therefore be performed only when necessary, as in the determination of reference values (e.g. protein or DNA content of the cell suspension). 4. Twenty four-fold determination of enzyme activities from one homogenate resulted in precisions between 4.5% (citrate synthase) and 14.4% (transketolase), which is satisfactory for the low activities (as low as 1 U/l) in the homogenate. 5. The reproducibility of enzyme activities, measured in homogenates of polymorphonuclear leukocytes from different blood samples drawn simultaneously, was only slightly worse than that of the continuous measurement method itself. Thus, the precision of the measurement of enzyme activity seems to be the main determinant of the overall method. In conclusion, the described procedure of separation, homogenization, and enzyme measurement in human polymorphonuclear leukocyte meets the requirements of biochemical or clinical trials and can be recommended for clinical metabolic studies.

[Registration and analysis of airway pressure and gas flow in ventilated patients. The "Hyper-DAQ Respiration Mechanics Recorder"]. / Registrierung und Analyse von Atemwegsdruck und Gasfluss beatmeter Patienten. Der "Hyper-DAQ Atmungsmechanikrekorder."

Respiratory data monitored in ventilated patients commonly consists of monitoring some inspiratory and expiratory pressures and volumes. For a more sophisticated analysis of respiratory mechanics in ventilated patients, a combined hardware and software system is presented that allows for continuous monitoring of airway pressure and gas flow. Gas flow is measured using a pneumotach. The "Hyper-DAQ" is an 8-channel 12-bit analog to a digital converter that can be connected to IBM PCs as well as to Macintosh computers using a standard RS 232 link. A special module consisting of three pressure transducers (airway pressure, differential pressure for a Fleisch head and ambient pressure) and five additional analog inputs is used for recording respiratory data. Once set up, the Hyper-DAQ records all the data in real time, independently of the host system that can query the data via the RS 232 link. The software runs on IBM and compatible PCs, as well as on Macintosh computers. The software simulates a strip-chart recorder and can be controlled by the keyboard and the mouse. We developed special software for the calibration of pressure and flow. Using models of the gas distribution in the lung compliance, resistance and lung time constants can be calculated from the raw data. For special purposes the data can be transferred to spread-sheet software. A mainstream CO2-detector connected to one of the additional analog inputs allows for additional data: alveolar ventilation, series deadspace, etc. The system presented can be recommended in routine work as well as for scientific studies in ventilated patients.

[Etiology, pathophysiology and clinical significance of hereditary fructose intolerance]. / Atiologie, Pathophysiologie und klinische Bedeutung der hereditären Fruktoseintoleranz.

Due to repeatedly described incidents in patients with undiscovered hereditary fructose intolerance, the application of fructose and sorbit-containing parenteral solutions is a topic vehemently discussed. This paper presents a survey of the literature dealing with the inborn defect of fructose-1-phosphate aldolase. The physiology and pathophysiology of fructose metabolism are described as well as the clinical appearance and diagnostic possibilities. The acute course of a fructose incompatibility is determined by a threatening decrease in the blood glucose level, which is attributed to the inhibition of several enzymes of glycolysis and gluconeogenesis by an intracellular accumulation of fructose-1-phosphate. Within hours a global functional breakdown of organs, which normally have the enzyme, occurs. The impairment of the liver function finds expression in a severe coagulopathy, the damage of the kidney leads to anuria. In chronic oral fructose supply, damage of the liver and small intestinal mucosa with corresponding gastrointestinal symptoms determine the clinical course. Concerning diagnosis, contrary to the liver biopsy and the fructose tolerance test, the mucosal biopsy with determination of fructose-1-phosphate aldolase activity has the advantage of greater specificity and is better tolerated by the patient. A total abstinence to fructose and sorbitol-containing solutions is not considered to be necessary when the rarity of the illness is taken into account and certain precautions are taken. These include a specific anamnesis of nutrition as well as a total abstinence from fructose and sorbitol in infants and in the unconscious patient. For clinical routine a simple fructose tolerance test is suggested.

The pseudotumor syndrome. Disorders of cerebrospinal fluid circulation causing intracranial hypertension without ventriculomegaly.

We report a series of eight cases that show a close resemblance to, but are not identical with, pseudotumor cerebri (PTC) as normally defined. The majority of these cases are characterized by raised intracranial pressure without ventriculomegaly. They include two cases of cranial venous outflow obstruction in which clinical or radiologic abnormalities precluded the diagnosis of PTC proper (cases 1 and 2); one case of chronic meningitis in which an abnormal cerebrospinal fluid (CSF) composition precluded the diagnosis of PTC (case 3); two cases without either papilledema or a measured increase of CSF pressure, which in other respects, particularly in response to treatment, resembled PTC (cases 4 and 5); and three cases of what is thought to represent an infantile form of PTC (cases 6 through 8). The purpose of the analysis of these cases is twofold. First, it is argued that these cases throw light on the mechanism of PTC itself, supporting a concept of a disturbance of CSF circulation in this condition, and that they are themselves illuminated by considerations of typical PTC. Second, the cases are used to frame a proposed classification of the pseudotumor syndrome aimed at broadening the diagnostic criteria applied currently to PTC. It is suggested that the pseudotumor syndrome has a single underlying mechanism (disturbed CSF circulation) and that recognition of this mechanism not only clarifies the pathophysiologic processes of PTC but also has important diagnostic and therapeutic implications.

[Maximal turnover rates of glycolysis enzymes and of the citrate cycle of separated granulocytes in the postoperative period]. / Maximale Umsatzraten an Enzymen der Glykolyse und des Zitratzyklus von separierten Granulozyten in der postoperativen Phase.

The human granulocyte is easy to obtain and shows a nearly complete enzymatic equipment. It therefore represents an interesting model for in-vitro studies of metabolic disorders under various clinical conditions. In the presented study, the activities of several enzymes of glycolysis and citric cycle are measured in granulocytes separated from surgical patients (n = 10). Blood samples of 20 to 40 ml were drawn 6.5 +/- 4.8 hours after termination of surgical procedure. All patients were artificially respirated and nourished intravenously according to the results of indirect calorimetry. Hexokinase (HK), pyruvate kinase (PK), lactate dehydrogenase (LDH), and isocitrate dehydrogenase (IDH) were measured photometrically in the cell homogenate. The values were compared to those determined in a group of healthy, not-anesthetized persons, nourished and studied identically (n = 12). In granulocytes separated from patients following major surgery we found increased activities of HK (29.8 vs. 24.1 mU/mg protein in controls), LDH (2,484 vs. 1,868 mU/mg protein, p less than 0.01) and IDH (41.5 vs. 35 mU/mg protein, p less than 0.05), and a reduced activity of PK (1,623 vs. 2,265 mU/mg protein, p less than 0.01). Assuming that the alterations in enzyme activities of isolated granulocytes reflect metabolic alterations of the whole organism to a certain extent, the results can be interpreted as a decreased induction of PK by insulin, an increase of lactate recycling via Cori cycle (LDH), and a stimulated substrate flux in citric cycle (IDH). The separated human granulocyte is recommended as a model of posttraumatic metabolic disorders. It should be taken into consideration for studies leading to further improvement of nutrition during posttraumatic glucose mal-utilization.

[Procedure for calculating various parameters of the metabolism of amino acid mixtures]. / Verfahren zur Berechnung verschiedener Parameter des Stoffwechsels von Aminosäurengemischen.

For the evaluation of indirect calorimetry, elements are used, which specify the relation between nitrogen (N) excretion and amount of oxidized amino acids (AS/N) and between nitrogen excretion and oxygen-/carbon dioxide-exchange of the corresponding amounts of amino acids (O2/N, CO2/N). These elements are only valid for the amino acid mixture which was used for their determination, and only under the condition of complete combustion of deaminized amino acid skeletons. We developed a computer program, which is able to simulate complete oxidation, maximal gluconeogenesis, and maximal lipogenesis for a given amino acid mixture of any composition. The parameters AS/N, O2/N and CO2/N were calculated by the program for various parenteral amino acid solutions. Range of error was determined exemplarily for the use of standard parameters. The calculations demonstrate errors up to 50% for the calculation of substrate turnover in indirect calorimetry, depending on composition and actual metabolism of amino acid mixtures. As long as these influencing factors are not known in stress metabolism, we recommend to use those elements, which were calculated for the amino acid solution in use, assuming complete combustion.

[The effect of nifedipine and fentanyl on changes in the circulatory reaction to endotracheal intubation]. / Der Einfluss von Nifedipin und Fentanyl auf Veränderungen der Kreislaufreaktion bei endotrachealer Intubation.

UNLABELLED: Recommendations for prevention of hypertension and tachycardia during the induction of anesthesia include the use of fentanyl and antihypertensive drugs and superficial anesthesia of the throat. Nifedipine has been used to treat acute hypertension and in many cases it has proved superior to other antihypertensive drugs. The present study was designed to find whether prophylactic injection of nifedipine alone or in combination with fentanyl can prevent cardiovascular responses during endotracheal intubation. METHODS: A total of 140 female patients (ASA groups I or II) with no history of arterial hypertension were randomly allocated to 7 groups: group K was the control group, in which patients received only saline solution; patients in groups 0,1F; 0,2F; 0,3F received 0.1, 0.2 or 0.3 mg fentanyl, respectively; those in group 1,0N, 1 mg nifedipine; those in group 0,5N + 0,1F, 0.5 mg nifedipine, plus 0.1 mg fentanyl; and those in group 1,0N + 0,1F 1 mg nifedipine plus 0.1 mg fentanyl. Blood pressure and heart rate were measured at 1 min intervals. After estimation of control values the prophylactic drug or combination of drugs was injected. Anesthesia was induced in the conventional manner. Plasma concentrations of epinephrine and norepinephrine were analyzed before intubation and at 5, 30 and 60 min intervals after intubation. Side-effects, especially respiratory depression and arrhythmia, were carefully recorded. RESULTS: In group K only systolic BP increased significantly after intubation. In the other groups the peak systolic blood pressure was not statistically different from the preinjection values. Diastolic BP increased significantly after intubation in all but two groups: in group 0,3F and in group 1,0N + 0,1F there was no significant difference in diastolic BP compared with the control values. The heart rate increased significantly in the control group after intubation as well as in groups 0,1F and 0,2F. In patients receiving 0.3 mg fentanyl there was no change in HR after intubation. Administration of 1 mg nifedipine alone (group 1,0N) or in combination with 0.1 mg fentanyl (group 1,0N + 0,1F) caused tachycardia even before intubation, whereas the combination of 0.5 mg nifedipine and 0.1 mg fentanyl did not result in a significant increase of HR following intubation. In all groups, epinephrine concentrations were significantly lower 5 min after intubation. A return to the control values was observed after 60 min in all groups except group 0,1F. Serum concentrations of norepinephrine were lower 5 min after intubation in all groups and were still low in groups 0,1F , 0,2F, 0,5N+0,1F and 1,0N+0,1F up to 60 min after intubation. Side-effects and adverse effects were checked for in the present study. An increase in heart rate was observed during induction in almost every group. More pronounced changes were recorded in groups 1,0N and 1,0N+ 0,1F receiving 1 mg nifedipine.(ABSTRACT TRUNCATED AT 400 WORDS)

[An on-line computer procedure for the analysis of pressure-volume relations in ventilated intensive care patients]. / Ein On-line Computerverfahren zur Analyse von Druck-Volumen-Beziehungen am beatmeten Intensivpatienten.

The inspiratory pressure-volume relationship (PV curve) describes elastic and viscous attributes of the respiratory system. The most frequently considered parameter is the quasi-static compliance, which has been used for evaluating optimal positive end-expiratory pressure (PEEP) in the treatment of patients with adult respiratory distress syndrome (ARDS). According to Falke and others, this method has not fulfilled its purpose. Since certain effects of PEEP ventilation such as the recruitment of lung areas on the one hand and the overdilatation of opened areas on the other may be reflected in different courses of parts of the PV curve, the consideration of discrete points on this curve may aid in developing mechanical criteria for the evaluation and control of artificial ventilation. Depending on lung elasticity, resistance, and tidal volume, the PV curve has a characteristic shape: initially it increases progressively until a certain airway pressure is reached, then it turns to a regressive incline. As irregularities of the PV curve due to oscillations of the respiratory gases cannot be avoided in practice, certain points (e.g. the inflection point) cannot be determined directly on the basis of the measured sample pairs. Therefore, we developed an on-line analysis of the PV curve, applying a polynomial function by least-square-fit procedure. The transthoracic pressure gradient was measured at the endotracheal tube by a Statham transducer. Inspiratory flow was measured using a Fleisch pneumotachograph with a differential pressure transducer. The flow-pressure signals were registered with a personal computer including an analog/digital interface board. Sample time was set for 10 ms.(ABSTRACT TRUNCATED AT 250 WORDS)

[Assessment of fluid content of the lung by thoracic radiography. Comparison of extravascular lung water measurement and results of radiological estimation methods]. / Beurteilung des Flüssigkeitsgehaltes der Lunge anhand des Thorax-Röntgenbildes. Vergleich der Messung des extravaskulären Lungenwassers und der Ergebnisse radiologischer Beurteilungsmethoden.

Extravascular lung water (EVLW) was determined with the thermal-dye double-indicator method (119 individual measurements) in 23 patients in an intensive-care unit, and the results were compared with estimates made from largely standardized portable chest X-ray films, using the staging method of Sibbald as well as that of Halperin. There was a significant correlation with the measured EVLW for both methods. Radiologically "normal" films corresponded to a mean EVLW value of 8.4 ml/kg body-weight. Radiologically judged adjacent stages did not in all cases compare with corresponding measured EVLW values. But when EVLW values were clearly abnormal, the X-ray films always demonstrated massive interstitial or alveolar infiltrations. Measurement of EVLW enables one accurately to judge the fluid contents of the lung and is superior to the assessment of the chest X-ray film.

[Changes in pulmonary hemodynamics, gas exchange and extravascular lung fluid in esophageal resection]. / Veränderungen der pulmonalen Hämodynamik, des Gasaustausches und des extravaskulären Lungenwassers während Osophagusresektion.

Postoperative convalescence after esophagectomy is frequently complicated by pulmonary insufficiency and a high mortality rate. The literature and our own observations suggest that pathological changes actually begin during the operative procedure; we therefore studied 11 male patients during and after esophageal surgery by monitoring heart rate, systemic and pulmonary arterial pressures, cardiac output, extravascular lung water (EVLW), cardiac index, and systemic (TPR) and pulmonary vascular resistance (PVR). Blood samples were taken for analysis of epinephrine, norepinephrine, serotonin, and arterial and mixed-venous blood gases. The changes were found to be most marked during esophageal resection: PaO2 decreased from 217 to 147 mmHg while PaCO2 increased, i.e. pulmonary gas exchange was disturbed (Fig. 4). PVR (Fig. 3) and mean pulmonary arterial pressure (MPAP) (Fig. 2) increased after esophagectomy. Norepinephrine, but not epinephrine (Fig. 6), increased continuously until the end of the operation. EVLW was slightly elevated at approximately 9 ml/kg body weight before operation and did not change during surgery. Six patients who developed severe pulmonary complications showed lung water retention up to 18 ml/kg body weight on the 4th postoperative day (Fig. 5). Compression of the heart and lungs as well as injury of the vagus nerve during esophagectomy may provoke increased MPAP, PVR, and disorders of pulmonary gas exchange. Furthermore, the non-respiratory function of the lung must be taken into consideration: the lung is known to have clearance activities for various endogenous substances such as norepinephrine, serotonin, some prostaglandins, and bradykinin. Most of these substances may provoke vasoconstriction followed by disturbances of microvascular permeability and gas exchange in the lung.(ABSTRACT TRUNCATED AT 250 WORDS)

[Effect of L-lysine-induced amino acid imbalance on nitrogen balance in patients treated by total parenteral nutrition]. / Auswirkung einer durch L-Lysin ausgelösten Aminosäuren-Imbalanz auf die Stickstoffbilanz bei vollständig parenteral ernährten Patienten.

Cumulative nitrogen balances of 109 patients in 3 groups under total parenteral nutrition were studied with regard to their daily intake of l-lysin. Patients in group 1 who received a mean daily amount of 4.5 g l-lysin exclusively from the amino-acid solution showed a cumulative nitrogen balance of -51.9 g N 10 days into the study. Patients in groups 2 and 3 received, additionally, l-lysin HCl for prophylaxis or therapy of metabolic alkalosis. Thus patients in group 2 received 5.3 g l-lysin (nitrogen balance -101.4 g N/10 days) and in group 3, 8.5 g l-lysin (nitrogen balance -97.6 g N/10 days). The markedly higher negative nitrogen balance in these groups is interpreted as the effect of an amino acid imbalance due to inadequate l-lysin intake; therefore, l-lysin should no longer be used for treatment of metabolic alkalosis in patients under total parenteral nutrition.

[Critical evaluation of changes in circulating blood volume, hematocrit, hemoglobin and plasma protein concentration for the calculation of normotonic fluid losses]. / Kritische Bewertung der Anderung des zirkulierenden Blutvolumens, des Hämatokritwertes, der Hämoglobin- und Gesamteiweisskonzentration für die Berechnung der Menge normotoner Flüssigkeitsverluste.

Normotonic fluid losses always lead to intravascular hypovolemia and subsequently to hypovolemic shock. Unfortunately, there are no diagnostic methods sufficient to calculate the extent of normotonic losses for fluid therapy. Therefore, indirect parameters such as changes in hemoglobin concentration, hematocrit, or plasma protein concentration are usually used for monitoring fluid therapy. This paper presents the results of our study in ten healthy volunteers. We investigated whether changes in circulating blood volume or hematocrit, hemoglobin, and plasma protein concentration indicate the amount of normotonic fluid loss in dehydrated humans. Normotonic fluid losses were induced using furosemide in repeated doses of 20 mg. Control measurements were carried out before furosemide administration (ZDM1 = time of sample taken) and after 2000 (ZDM2) and 3000 ml urinary output (ZDM3). We measured hematocrit as well as concentrations of hemoglobin, plasma protein, sodium, potassium, and chloride using standard laboratory methods. Hematocrit values were corrected for trapped plasma (3%) and the body/venous hematocrit ratio (0.91). Circulating blood volume was measured using J-131 RIHSA and the "volemetron" introduced by Williams and Fine. Plasma volume and plasma water volume were calculated. After checking the data for normal distribution, statistics were calculated using the paired t test (P less than 0.01). The results are listed in Table 2. We calculated normotonic fluid losses on the basis of plasma and urinary sodium concentrations and found them to be 1720 +/- 155 ml (ZDM2) and 2392 +/- 262 ml (ZDM3).(ABSTRACT TRUNCATED AT 250 WORDS)