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Biomedical subjects

R Haeckel

Publications and source records attributed to R Haeckel.

At least 37 records · Page 2Linked to original sources
PubMed1990

Inhibition of mitochondrial carnitine acylcarnitine translocase by hypoglycaemia-inducing substances.

The rate of mitochondrial carnitine-carnitine exchange mediated by carnitine acylcarnitine translocase was measured in the presence of the two hypoglycaemia-inducing drugs, 2-(3-methyl-cinnamyl-hydrazono)-propionate and 2-(3-phenylpropoxyimino)-butyric acid (BM 13.677). Both substances caused a concentration-dependent decrease in the rate of carnitine uptake in guinea pig liver mitochondria. Apparent initial influx rates were decreased by 75% and 80% at a concentration of 2 mmol/l 2-(3-methyl-cinnamyl-hydrazono)-propionate and 2-(3-phenylpropoxyimino)-butyric acid, respectively. Intraperitoneal injections of 212 mumol 2-(3-phenylpropoxyimino)-butyric acid or 21 mumol 2-(3-methyl-cinnamyl-hydrazono)-propionate per kg body weight caused a noticeable decrease in blood glucose concentration. A significant fall of the blood ketone body concentration was achieved with 2-(3-methyl-cinnamyl-hydrazono)-propionate or 2-(3-phenylpropoxyimino)-butyric acid, at dosages of 21 and 255 mumol/l, respectively. Furthermore there was a dose-dependent increase in the plasma free fatty acid concentration in the presence of 2-(3-methyl-cinnamyl-hydrazono)-propionate. This increase, however, was much less pronounced with 2-(3-phenylpropoxyimino)-butyric acid. Metabolic effects of 2-(3-methyl-cinnamyl-hydrazono)-propionate are consistent with an inhibition of long-chain fatty acid transport, whereas an additional mechanism of action has to be assumed for 2-(3-phenylpropoxyimino)-butyric acid.

Animals↗
PubMed1990

European Multicentre Evaluation of the ESAT 6660.

The analytical performance of the glucose analyser ESAT 6660 from Eppendorf was studied according to the ECCLS guidelines and partly according the SFBC protocol in a multicentre evaluation involving laboratories from three European countries. The glucose determination in serum and in haemolysate was studied. The following results were obtained. 1. The precision was as good as or better than the precision of the comparison instruments. The coefficients of variation were between 1.1 and 3.4% for the between-days imprecision and between 0.35 and 1.45% for the within-run imprecision experiment. 2. The recovery of control sera values compared with the hexokinase method was between 94.3 and 102.6%. 3. With patient specimens as good agreement was found between the results obtained with the ESAT 6660 and the different comparison instruments (ASTRA, Hitachi 737 and ACP 5040). 4. A drift effect of 1.1-2.3% occurred in 5 of 21 experiments, depending on the individual enzyme membrane. 5. Sample carry-over was not observed. 6. A linearity between 0.5 and 50 mmol/l was found, exceeding the manufacturer's claims. 7. Several different endogenous and exogenous interferences were investigated. No interfering effect was detected for endogenous substances. A positive interference was observed by ascorbic acid at a concentration above 350 mg/l. 8. The practicability of the instrument was judged as very good. It was considered as a disadvantage that the instrument is not capable of piercing sample lids. Also the numeration of samples is not very convenient.

Blood Chemical Analysis↗
PubMed1990

Relationship between intraindividual variation of the saliva/plasma- and of the arteriovenous concentration ratio as demonstrated by the administration of caffeine.

The use of saliva instead of venous blood for monitoring drugs has many advantages. Its usefulness has, however, been questioned, because of the variability of the intraindividual saliva/plasma ratio. Among other reasons, this variability can result from the fluctuation of the arteriovenous blood concentration ratio. The present work represents a detailed investigation of this phenomenon, using caffeine as an example. This phenomenon is observed when the concentration of free diffusible substances differs in the central and peripheral compartment, depending on the pharmacokinetic phase. In such cases, the salivary concentration more closely reflects the cellular concentration in organs of the central compartment than that of peripheral venous blood.

Adult↗
PubMed1990

Stimulation of glucose metabolism in human blood cells by inhibitors of carnitine-dependent fatty acid transport.

According to a well accepted hypothesis, increased fatty acid oxidation can lead to hyperglycaemia by stimulating gluconeogenesis and reducing glycolysis. Therefore, inhibitors of fatty acid metabolism should cause hypoglycaemia by inhibiting gluconeogenesis and activating glycolysis. Various substances were tested to validate this hypothesis with regard to glucose oxidation in human mononuclear leukocytes and thrombocytes. 2-(3-Methyl-cinnamyl-hydrazono)-propionate, an inhibitor of the carnitine acyltransfer system was found to cause hypoglycaemia in whole animals and to inhibit gluconeogensis in the perfused guinea pig liver, while the acetyl-CoA/CoASH ratio was decreased. This substance stimulated the metabolism of glucose to CO2 in human mononuclear leukocytes and especially in platelets. This effect could be potentiated if concanavalin A and 2-(3-methyl-cinnamyl-hydrazono)-propionate were applied simultaneously. Under these conditions, however, fatty acid oxidation was no longer inhibited. From these results, it can be concluded that the activation of glucose oxidation by 2-(3-methyl-cinnamyl-hydrazono)-propionate is independent of its effect on fatty acid metabolism. Other inhibitors of fatty acid metabolism which were also investigated behaved similarly.

Blood Glucose↗
PubMed1989

Reasons for intraindividual inconstancy of the digoxin saliva to serum concentration ratio.

When a constant dose of digoxin was administered orally over several days, the digoxin concentration in saliva and erythrocytes rose faster than in serum. Thus, the saliva/serum concentration ratio was below 1.0 after a single dose and above 1.0 in the steady state. The digoxin concentration was relatively high in "unstimulated" (more or less spontaneous) saliva and decreased with stimulation of the salivary flow rate. It therefore appeared that the actual salivary digoxin concentration depended on 2 components: the digoxin concentration in "stimulated" saliva depended only on the rapid diffusion from the blood into saliva, and the concentration in the "unstimulated" saliva depended on the rapid diffusion and on a slower exchange with the intracellular compartment. It is suggested that unstimulated saliva reflects the intracellular digoxin concentration and stimulated saliva reflects the free digoxin concentration of the serum. Both effects must be taken in account when interpreting the saliva/serum ratio, and they may explain conflicting results in the literature.

Digoxin↗
PubMed1989

Measurement of proteins with the Behring Nephelometer. A multicentre evaluation.

The selective multi-protein analyser Behring Nephelometer was examined according to the ECCLS guidelines in a multicentre evaluation involving five laboratories. IgG, IgA, IgM, C-reactive protein, C3c, C4, apolipoprotein A-I and B were measured in serum, and albumin and IgG were measured in cerebrospinal fluid. All values obtained were included in the evaluation without correcting for outliers. The trial, which lasted three months and involved over 20,000 analyses, basically yielded the following results: 1. The precision was generally better than that of comparative procedures. For the majority of methods, the between-day coefficients of variation were below 4.5%. The highest coefficient of variation was 7.2% (for C-reactive protein) and the lowest 1.35% (for C3c). 2. The fraction of assigned values of control materials varied between 0.95 and 1.08. 3. Good agreement was found with results from the comparison procedures: Beckman ICS, Behring Laser Nephelometer, Hyland Laser Nephelometer. 4. No carry-over effects were observed. 5. No interferences were observed for IgG, IgA and IgM determinations using hyperbilirubinaemic or haemolytic samples. In contrast lipaemic samples and some with monoclonal immunoglobulin M showed an influence on the immunoephelometric reaction. 6. Because of the large measuring range, it is necessary to repeat analyses only in extremely rare cases. 7. During the entire evaluation period no instrument malfunctions or interruptions occurred. As a result of its reliability, the Behring Nephelometer is well suited for routine operation and emergency analyses in medium and large-sized laboratories.

Albumins↗
PubMed1989

European multicentre evaluation of the ABBOTT Spectrum clinical chemistry analyzer.

The analytical performance of the selective multitest ABBOTT Spectrum analyser was studied according to the ECCLS guidelines and partly the CERMAB protocol in a multicentre evaluation involving laboratories from six European countries. Fifteen analytes, including the electrolytes sodium, potassium and chloride, were measured each in at least 3 laboratories, all at 37 degrees C, except the electrolytes, which are measured at room temperature. The trial lasted approximately three months and involved the collection of over 60,000 data points. It yielded the following results: 1. The precision was at least as good as the precision obtained with the comparison instruments. The majority of the coefficients of variation were between 1 and 4%. 2. The recovery for method assigned control sera values was, with few exceptions, within 10%. 3. Good agreement with respect to the method assigned values of control materials and method comparison with patient specimens to different instruments (e.g. SMAC, Hitachi 737, RA 1000) was found. 4. No drift was observed. 5. Reagent-related carry-over was not found. Specimen-related carry-over was detected in some cases, the deviation being of little or no clinical significance. 6. The manufacturer's claims regarding method linearity were as stated or exceeded. 7. The open system capability was tested and rated as very convenient. 8. The practicability of the instrument was very good.

Blood Chemical Analysis↗
PubMed1989

Measurement of leukocyte elastase/alpha 1-proteinase-inhibitor complex using a homogeneous and a heterogeneous enzyme-immunoassay.

The heterogeneous 2 h elastase/alpha 1-proteinase-inhibitor enzyme-linked immunosorbent assay was compared with a newly developed homogeneous 20 min immunoactivation test. The within-run and between-days coefficients of variation for both tests were satisfactory. Good agreement was found between the two tests, using specimens from 140 patients. In conclusion, the 20 min immunoactivation test is able to replace the 2 h elastase/alpha 1-proteinase-inhibitor enzyme-linked immunosorbent assay.

Adolescent↗
PubMed1988

Effects of 2-(3-methyl-cinnamyl-hydrazono)-propionate on fatty acid and glucose oxidation in the isolated rat diaphragm using 14C-labelled substrates. Hydrazonopropionic acids, a new class of hypoglycaemic substances, VIII.

The influence of 2-(3-methyl-cinnamyl-hydrazono)-propionate on the utilization of various substrates in isolated rat hemidiaphragms was investigated in comparison with other hypoglycaemic compounds. The effect of 2-(3-methyl-cinnamyl-hydrazono)-propionate was concentration-dependent. At a concentration of 0.5 mmol/l 2-(3-methyl-cinnamyl-hydrazono)-propionate, glucose utilization increased from 0.276 +/- 0.043 mumol.g-1.l-1 to 0.894 +/- 0.303 mumol.g-1.l-1 (p less than 0.05). Pyruvate and lactate utilization were stimulated to a lesser extent, while acetate utilization remained nearly constant. At a concentration of 2 mmol/l 2-(3-methyl-cinnamyl-hydrazono)-propionate, the oxidation of palmitate decreased from 0.214 +/- 0.017 mumol.g-1.l-1 to 0.060 +/- 0.005 mumol.g-1.l-1, while the oxidation of octanoate was not decreased. These findings point to a stimulation of the glycolytic flux by inhibition of long-chain fatty acid oxidation.

Animals↗
PubMed1988

Endotoxaemia in patients with Crohn's disease: a longitudinal study of elastase/alpha 1-proteinase inhibitor and Limulus-amoebocyte-lysate reactivity.

During intensive care, the severity of gut-derived systemic endotoxaemia in 16 patients with active Crohn's disease was characterized by the simultaneous determination of elastase/alpha 1-proteinase-inhibitor and Limulus-amoebocyte-lysate-reactivity. Using both assays in 15/16 patients the detectable endotoxic activity during the disease course was reflected by a parallelism between elastase/alpha 1-proteinase-inhibitor and Limulus-amoebocyte-lysate-reactivity. In 8 gut-irrigated patients, significantly lower elastase/alpha 1-proteinase-inhibitor concentrations and Limulus-amoebocyte-lysate-reactivities were measured compared with 8 gut-nonirrigated patients. The Crohn's disease activity index and the van Hees activity index as well as the inpatient time were significantly lower in lavage patients compared with gut-nonirrigated patients. It is concluded with that elastase/alpha 1-proteinase-inhibitor can be used as an alternative to the bioassayed Limulus-amoebocyte-lysate-reactivity in order to characterize systemic endotoxaemia.

Adolescent↗
PubMed1988

Method comparison of two test kits for the determination of elastase/alpha 1-proteinase-inhibitor complex.

A method comparison of the 4 h-elastase/alpha 1-proteinase-inhibitor test kit with a newly developed 2 h-version was performed. The within-run and between-days coefficients of variation as well as the recovery of the assigned values were satisfactory for both test kits. Good agreement was found between the 2 h- and 4 h-test kits using specimens from 160 patients. In conclusion, the 2 h-test kit can be used as an alternative for the determination of elastase/alpha 1-proteinase-inhibitor complex.

Adolescent↗
PubMed1988

Multi-centre evaluation of the Behring ELISA Processor II.

A multi-centre evaluation of the Behring ELISA Processor II in connection with the Enzygnost-tests from Behringwerke was performed by 3 laboratories following the ECCLS Guidelines for the Evaluation of Analysers in Clinical Chemistry. The performance characteristics were studied with analytical tests for anti-HBs1), HBsAg and anti-CMV2). This evaluation represents, to our knowledge, the first trial in clinical virology with guidelines primarily designed for clinical chemistry. The evaluation revealed that the highly automated Behring ELISA Processor II is a reliable tool in the virological laboratory. The data obtained showed low imprecision and good accuracy. The washing unit proved to be very efficient. No carry-over of reagents was detected in the dispenser system. Several improvements for further developments of the analyser are suggested. This multi-centre study has shown that the ECCLS protocol can be used to evaluate analysers and test systems in clinical virology.

Autoanalysis↗