In Vivo Clearance and Elimination of Nine Marker Substances during Hemofiltration with Different Membranes

The handling of low, middle and high molecular weight markers was examined in seven stable dialysis patients during hemofiltration with different membranes. Four membranes were examined in a randomized, crossover order (polysulfone, polyamide, AN69 polyacrylonitrile, Asahi polyacrylonitrile) by measuring plasma and dialysate concentrations of phosphate, creatinine, vitamin B12, β2-microglobulin, furanic acid, hippuric acid, retinolbinding protein, alpha-1-antitrypsin, and albumin. Sieving coefficients and plasma clearances of β-microglobulin or retinol-binding protein were markedly or slightly lower during hemofiltration with the Asahi polyacrylonitrile membrane than with the other membranes (highest removal with polysulfone/AN69 polyacrylonitrile membranes). No differences of obvious clinical relevance could be seen between the four membranes. A high β2-microglobulin removal rate might be important to prevent dialysis-associated amyloidosis.

Strychninvergiftung

HISTORY AND ADMISSION FINDINGS

A 46-year-old man presented two hours after ingestion of about 250 mg strychnine with severe violent, generalized convulsions, triggered by external stimuli. During the convulsion-free periods there were no abnormal signs in the physical examination.

INVESTIGATION

The presence of strychnine was confirmed by urine analysis with gas chromatography-mass spectrometry.

TREATMENT AND COURSE

Because diazepam as anticonvulsant of choice was not effective in abating the convulsions the patient was intubated. A combination with midazolam, fentanyl and pancuronium was effective in controlling the convulsions. The patient was discharged from ICU on day three.

CONCLUSION

Fatal outcome of strychnine poisoning demands an aggressive management with early intubation, control of muscle tremors and prevention of rhabdomyolisis and renal failure.

Kindling-induced overexpression of Homer 1A and its functional implications for epileptogenesis

Despite an extensive research on the molecular basis of epilepsy, the essential players in the epileptogenic process leading to epilepsy are not known. Gene expression analysis is one strategy to enhance our understanding of the genes contributing to the functional neuronal changes underlying epileptogenesis. In the present study, we used the novel MPSS (massively parallel signature sequencing) method for analysis of gene expression in the rat kindling model of temporal lobe epilepsy. Kindling by repeated electrical stimulation of the amygdala resulted in the differential expression of 264 genes in the hippocampus compared to sham controls. The most strongly induced gene was Homer 1A, an immediate early gene involved in the modulation of glutamate receptor function. The overexpression of Homer 1A in the hippocampus of kindled rats was confirmed by RT-PCR. In order to evaluate the functional implications of Homer 1A overexpression for kindling, we used transgenic mice that permanently overexpress Homer 1A. Immunohistochemical characterization of these mice showed a marked Homer 1A overexpression in glutamatergic neurons of the hippocampus. Kindling of Homer 1A overexpressing mice resulted in a retardation of seizure generalization compared to wild-type controls. The data demonstrate that kindling-induced epileptogenesis leads to a striking overexpression of Homer 1A in the hippocampus, which may represent an intrinsic antiepileptogenic and anticonvulsant mechanism in the course of epileptogenesis that counteracts progression of the disease.

Features of malignancy in a benign pheochromocytoma

Pheochromocytomas are rare conditions with a prevalence of 1-2/100,000 in the general population and 1/1,000 hypertensive subjects [1]. 10% of pheochromocytomas are malignant and various attempts have been made to find useful prognostic indicators of malignancy. In general, increased plasma or urine dopamine concentrations or increased homovanillic acid excretion and lack of 131-methyliodo-benzylguanidine uptake have been associated with malignancy [2]. However, to date no specific metabolic, radiologic or histopathologic features of either benign or malignant pheochromocytomas allowing the safe diagnosis of one or the other have been identified. The diagnosis of malignant pheochromocytoma can be made only in the presence of local tissue invasion or distant metastases. We present a benign pheochromocytoma exhibiting several features suggestive of malignant disease.

Glucose turnover in humans in the basal state and after intravenous glucose: a comparison of two models

This study investigated the ability of two models to represent glucose kinetics in the basal steady state and during an intravenous glucose tolerance test (IVGTT). Six young nonobese male subjects were studied after an overnight fast. Two bolus injections of [U-13C]glucose were given 150 min apart, the first without and the second together with concomitant injection of unlabeled glucose. [3-3H]glucose was constantly infused throughout the study and served to provide an independent means for evaluation of system responses. A linear time-invariant three-compartmental model and the two-compartment time-variant model proposed by Caumo and Cobelli were used to interpret measured time courses of [U-13C]glucose and to reconstruct endogenous glucose production and glucose removal. The ability of the two models to describe the glucose tracer time course was comparable. Simulation studies showed that the two-compartmental time-variant system better predicted measured [3-3H]glucose concentration profiles than did the three-compartmental time-invariant model. However, endogenous glucose production and the integral of excess glucose removal over basal during the IVGTT derived from the two models were almost identical.

Hypothalamic-pituitary activation does not differ during human and porcine insulin-induced hypoglycemia in insulin-dependent diabetes mellitus

Although pituitary hormones play only a minor role in acute hormonal counterregulation during insulin-induced hypoglycemia, their concomitant secretion with the profound sympathoadrenal response provides an indicator of hypothalamic-pituitary activation. The release of different amounts of beta-endorphin, growth hormone, and adrenocorticotropin during human (HI) and porcine (PI) insulin-induced hypoglycemia would serve as a pointer to a different insulin species effect on hypothalamic-pituitary response. We performed a controlled, double-blind study with randomization to either HI or PI to compare insulin effects during developing and established hypoglycemia. The glucose clamp technique was used to lower the blood glucose concentration stepwise (3.3, 2.2, 1.7 mmol/l) over similar periods in ten patients with insulin-dependent diabetes mellitus. beta-endorphin, growth hormone, and adrenocorticotropin levels were determined by radioimmunoassay from arterialized blood at the above plateaus. A different action of HI or PI on peripheral glucose metabolism was not found. Pituitary hormones increased significantly during hypoglycemia (analysis of variance for hypoglycemic effects: beta-endorphin, P < 0.02; growth hormone, P < 0.04; adrenocorticotropin, P < 0.05). No insulin species effect was detected. Hypothalamic-pituitary activation during insulin-induced hypoglycemia is independent of the insulin species used, which supports earlier observations of an identical sympathoadrenal response during HI- and PI-induced hypoglycemia.

Comparison of a mechanized version of the 'König' reaction and a fluorescence polarization immunoassay for the determination of nicotine metabolites in urine

Smoking can be detected by the determination of cotinine in urine. We compared the performance of an automated modification of the 'König' reaction adapted to a centrifugal analyzer with an automated commercial fluorescence polarization immunoassay (TDX system). In the latter assay, cotinine, as the primary metabolite of nicotine, can be measured with high specificity. In contrast, the 'König' reaction also detects nicotine metabolites other than cotinine by a group colour reaction. Analysis speed of the 'König' reaction was about 66 samples/h with a detection limit 2 S.D. above the mean value of urine samples of non-smokers. Analysis speed of the TDX system was 41 samples/h. The coefficient of variation (C.V.) of both methods in smokers' urine was 8.6% ('König' reaction) vs. 3.4% (TDX system) in the high range and 16.4% vs. 9.5% in the low range. In a controlled, prospective study recruiting 86 cigarette-smoking volunteers, 83.7% were correctly classified as being smokers by both systems, 13.9% were classified as smokers by the 'König' reaction only and 2.4% were misclassified as non-smokers by both systems. Thus, the sensitivity of the 'König' reaction seems to be higher than in the TDX system (97.6% vs. 83.7%). Of 33 non-smoking individuals, 81.8% were correctly classified as non-smokers by both systems, 18.2 were misclassified as smokers by the 'König' reaction and no person was misclassified by the fluorescence polarization immunoassay. Thus, the specificity of the TDX system seems to be higher than that of the 'König' reaction (100% vs. 81.8%). We conclude that both systems are applicable to detect individuals who smoke regularly by simple urine testing. The higher specificity of the TDX system is outweighed by the higher sensitivity of the 'König' reaction at much lower cost.

In vivo clearance and elimination of nine marker substances during hemofiltration with different membranes

The handling of low, middle and high molecular weight markers was examined in seven stable dialysis patients during hemofiltration with different membranes. Four membranes were examined in a randomized, crossover order (polysulfone, polyamide, AN69 polyacrylonitrile, Asahi polyacrylonitrile) by measuring plasma and dialysate concentrations of phosphate, creatinine, vitamin B12, beta 2-microglobulin, furanic acid, hippuric acid, retinol-binding protein, alpha-1-antitrypsin, and albumin. Sieving coefficients and plasma clearances of beta 2-microglobulin or retinol-binding protein were markedly or slightly lower during hemofiltration with the Asahi polyacrylonitrile membrane than with the other membranes (highest removal with polysulfone/AN69 polyacrylonitrile membranes). No differences of obvious clinical relevance could be seen between the four membranes. A high beta 2-microglobulin removal rate might be important to prevent dialysis-associated amyloidosis.

Selected ion monitoring gas chromatography/mass spectrometry using uniformly labelled (13C)glucose for determination of glucose turnover in man

An optimized method is described for the mass fragmentographic determination of uniformly labelled (13C)glucose in human plasma using a butylboronic acid acetate derivative, and capillary gas chromatography. The advantages of the method are the ease and speed of the derivatization procedure, the small sample size, high precision (interassay coefficient of variation 5.7%), and applicability of a relatively low-cost mass spectrometer. This method allows glucose tracer experiments to be performed in man using the bolus injection technique, necessitating analysis of many samples. The results on glucose turnover obtained in a clinical experiment were in full agreement with previously published data.

Hippuric acid and 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid in serum and urine. Analytical approaches and clinical relevance in kidney diseases

Hippuric acid (HA) and 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid (FA) were determined in serum, plasma, ultrafiltrate and urine by gas chromatography (GC), high-performance liquid chromatography and GC with mass-selective detection, and the methods were compared. As determined by affinity chromatography and analysis of serum and ultrafiltrate, 0.5% of FA in serum occurs free and 99.5% is bound to albumin. In haemodialysed patients with chronic renal failure, the plasma levels of HA and FA are elevated in comparison with normal controls and hospital patients without kidney diseases: HA, 11.1 +/- 5.7 mg/dl (n = 86); FA, 1.9 +/- 1.2 mg/dl (n = 86). Gradual increases in HA in serum, depending on the creatinine concentrations, are found in non-dialysed patients with chronic renal failure. By haemodialysis and haemofiltration the HA levels are lowered (53-66 and 30-36%, respectively), whereas FA is not dialysable.

Determination of hippuric acid and furanic acid in serum of dialysis patients and control persons by high-performance liquid chromatography

A high-performance liquid chromatographic method for the determination of 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid (furanic acid) and hippuric acid in human serum is described. Quantitative data were obtained from 20 blood donors, 26 non-dialysis patients and 41 dialysis patients. In healthy persons hippuric acid ranged from 0.2 to 0.6 mg/dl, furanic acid from 0.13 to 0.53 mg/dl. In dialysis patients the mean concentration of hippuric acid was elevated to 17.2 mg/dl (range 1.7-50.8 mg/dl) and the mean concentration of furanic acid was elevated to 1.89 mg/dl (range 0.17-6.45 mg/dl). In patients without renal insufficiency the concentrations were not elevated. These data are in accordance with previous data obtained by gas chromatographic methods. Preliminary results indicate that hippuric acid and furanic acid may be more specific parameters than other uremic retention products, and better indicators for the need for dialysis treatment than urea or creatinine.

Panuveitis with positive serological tests for syphilis and Lyme disease

The Treponema pallidum hemagglutination test and the fluorescent treponemal antigen absorption test are commonly considered highly specific serologic tests for syphilis. We describe a patient with panuveitis and a positive serologic result for syphilis; however, in the absence of clinical findings, additional tests for Lyme disease (borreliosis) were positive as well, although by Western blot test the diagnosis was tentative. The clinical appearance of the panuveitis was similar to that of syphilitic uveitis accompanied by pseudopigmentosa-like areas in the anterior retina. In the presence of uveitis with an otherwise unexplained positive serologic result for syphilis, the differential diagnosis of Lyme disease should be considered.

Unusual course of a Chlamydia pneumonia in an infant with IgG2/IgG4-deficiency

An unusual case of Chlamydia trachomatis (C. trachomatis) pneumonia, complicated by the development of a pneumothorax, is reported in an IgG2/IgG4 deficient infant delivered by caesarean section. C. trachomatis was isolated initially from a throat smear and subsequently from pleural effusions. Serological examinations using the complement fixation test were negative in sera of both mother and child. However, using immunofluorescence the presence of an acute or recent infection was confirmed by IgM-antibodies in the serum of the infant and IgA-antibodies in the serum of the mother. At the age of 7 months the girl suffered from impetigo contagiosa which was partially resistant to antibiotic treatment. IgG-subclass deficiency was diagnosed after the onset of this disease and the girl was then treated by immunoglobulin transfusion.

New developments in medical microbiology: computer-assisted diagnosis and automated instruments

Time and accuracy required for diagnosis are two of the most important factors in medical microbiology. Computer-assisted diagnosis is one tool to overcome these problems. The software of such systems, much more than the hardware, is of utmost importance and both have to fulfill several items. 1) High flexibility and integration within the already existing working schemes of the laboratory. 2) Terminals in every laboratory. 3) High speed of calculation. 4) Online data transfer from automated instruments. 5) External terminals on intensive care units. 6) Epidemiological and etiopathological investigations have to be possible at any time. In the laboratory the burden of simple, repeating tasks is diminished, inquiries can be made in a minute and precise information about the epidemiological situation can be gained within a few hours. Thus, calculated antimicrobial therapy depending on the incidence of certain pathogens in given specimens in different departments is possible. In the case of fast-growing bacteria, preliminary reports, including susceptibility testing available within the first 24 h, are possible and will be of great help to the clinician in monitoring the calculated antimicrobial regimen. External terminals will allow continuous flow of data from the laboratory to wards and vice versa.

[Survival of Campylobacter jejuni in drinking water, river water and sewage]

Campylobacter jejuni (C. jejuni) has not been found by us in raw sewage or anaerobically stabilized sludge. Therefore the survival of C. jejuni has been tested in drinking water, river water and sewage. A suspension of about 10(7) C. jejuni per ml was filled into dialysis tubes which were placed in wire baskets and exposed. Exposition to drinking water was done using two continuously perfused containers in the laboratory, whereas exposition to sewage and river-water was performed at the local sewage treatment plant. Viable C. jejuni numbers per ml were reduced to zero in drinking water during five days starting from 10(6)/ml, in about two days in river water, starting from 10(8)/ml, and one and a half day in untreated sewage, starting from 10(7)/ml. E. coli showed no significant reduction in any of the experiments. Survival of C. jejuni in water seems to be restricted to a few days. The concentration of oxygen or nutrients in the water seems to be without relevance, whereas the most significant variable is temperature, which in our experiments was highest in the sewage and lowest in the drinking water containers.

Gas chromatographic profiling of phenolic acids in urine of patients with cirrhosis of the liver

Phenolic acids are analysed within the profile of the organic acids in urine of patients with cirrhosis. For the following constituents an increased urinary excretion is observed: 4-hydroxyphenylpyruvic acid, 4-hydroxyphenyllactic acid, 4-hydroxyphenylacetic acid, 4-hydroxybenzoic acid, 4-hydroxyhippuric acid, vanillic acid, homovanillic acid, 4-hydroxymandelic acid, 4-hydroxy-3-methoxyphenylpropionic acid and p-cresol. The phenols are metabolites of tyrosine and are produced in the liver, in extrahepatic tissues and by intestinal microorganisms. They are suggested as biochemical control parameters for the metabolizing function of the liver, for the effect of therapy and for the existence of portal-systemic venous collaterals.

Gas chromatographic and gas chromatographic—mass spectrometric analysis of organic acids in plasma of patients with chronic renal failure

Apart from increased concentrations of aliphatic dicarboxylic acids and phenolic aromatic acids in plasma from patients with chronic renal failure, there is large elevation of a furanoid acid, 3-carboxy-4-methyl-5-propyl-2- furanpropionic acid, and of hippuric acid. The levels of 3-hydroxy- and 4- hydroxyhippuric acid are also raised. The quantitative results are as follows: furanoid acid in hemodialysis patients, 1.4 +/- 0.6 mg/dl; in healthy individuals, 0.2 +/- 0.1 mg/dl; hippuric acid in hemodialysis patients, 9.8 +/- 6.5 mg/dl; in health individuals, 0.4 +/- 0.5 mg/dl. Both compounds are dialysable, but less effectively than creatinine and urea. The mean elimination rate of the furanoid acid is only 21%.

Analysis of the oxocarboxylic acid fraction in serum and urine as O-methyloximes by thermionic specific detection

After O-methyloximation of the carbonyl functions, the organic acids in serum and urine are extracted by anion-exchange chromatography, transformed into the methyl esters and pre-fractionated by thin-layer chromatography. In one of the four fractions and on the basis of the nitrogen in the O-methyloxime esters, the profiles of the oxocarboxylic acids are analyzed by gas chromatography with thermionic specific detection. The method has good specificity for the oxocarboxylic acids and is suitable for comparative studies. During diabetic or fasting ketoacidosis the serum concentrations of 3-oxobutyric acid and of the amino acid metabolites 2-oxobutyric, 2-oxoisovaleric and especially 2-oxo-3-methylvaleric and 2-oxoisocaproic acid are increased. In urine mainly 3-oxobutyric acid and only small amounts of the 2-oxocarboxylic acids are excreted.

Gas chromatography-mass spectrometry of saturated and unsaturated dicarboxylic acids in urine

Saturated and unsaturated dicarboxylic acids in urine are analyzed within the total profile of organic acids, using the methyl ester derivatives. Twenty-three acids with two carboxyl groups were identified. The method is employed for comparative studies of the excretion of dicarboxylic acids by individuals with normal and with increased fatty acid oxidation. In the group of the unsaturated acids, the cis-trans isomers mesaconic acid and citraconic acid, the two isomers of 3-methylglutaconic acid and muconic acid are characterized by the mass spectra of their methyl esters. The saturated unbranched and even-numbered dicarboxylic acids are elevated during fasting and diabetic ketoacidosis. In the total profile of the organic acids, succinic and adipic acid are indicators for ketoacidotic states.