Heparin-induced thrombocytopenia in patients requiring prolonged intensive care unit treatment after cardiopulmonary bypass.

BACKGROUND: The diagnosis of heparin-induced thrombocytopenia (HIT) is problematic in postcardiac surgery (CS) intensive care unit (ICU) patients, as there are multiple potential explanations for thrombocytopenia and the presence of anti-platelet factor 4/heparin antibodies is not highly specific for HIT. Two platelet count profiles for HIT - a 40% or greater fall in platelet count beginning on or after day 5 (pattern 1) and persisting thrombocytopenia (< 100 x 10(9) L(-1)) beyond day 7 (pattern 2) - have been described in post-CS patients. METHODS AND RESULTS: We examined the platelet count profiles of 329 consecutive post-CS patients who required ICU treatment beyond 7 days. Although 70 patients (21.3%) developed thrombocytopenia (57.1% pattern 1, 42.9% pattern 2), the overall incidence of HIT was only 1.8% [6/329; 95% confidence interval (95% CI) 0.7-3.9%] in these ICU patients, with more HIT patients showing a pattern 2 than a pattern 1 platelet count decrease (four vs. two patients). Notably, pattern 2 patients with HIT also showed a new proportional fall of > 30% in platelet count between postoperative days 5 and 10. Among the remaining 2242 post-CS patients without a prolonged ICU stay, only three (0.1%; 95% CI 0.03-0.4%) developed symptomatic HIT (OR 0.07; 95% CI 0.01-0.3; P = 0.0002 vs. ICU patients), all presenting with pattern 1. CONCLUSIONS: Among post-CS ICU patients, a postoperative platelet count fall between days 5 and 10 increases diagnostic specificity for HIT, irrespective of whether this platelet count fall occurs after postoperative platelet count recovery (pattern 1) or is superimposed upon persisting postoperative thrombocytopenia (pattern 2). A prospective study is required in order to validate the findings of this retrospective analysis.

Lepirudin in patients with heparin-induced thrombocytopenia - results of the third prospective study (HAT-3) and a combined analysis of HAT-1, HAT-2, and HAT-3.

OBJECTIVES: To assess efficacy and safety of lepirudin in patients with heparin-induced thrombocytopenia (HIT) in a prospective study (HAT-3) as well as in a combined analysis of all HAT study data. PATIENTS/METHODS: Patients with laboratory-confirmed HIT were treated with lepirudin in three different aPTT-adjusted dose regimen and during cardiopulmonary bypass (CPB). Endpoints were new thromboembolic complications (TEC), limb amputations, and death and major bleeding. A historical control group (n = 120) was used for comparison. RESULTS: After start of lepirudin in 205 patients treated in HAT-3, the combined endpoint occurred in 43 (21.0%). Thirty (14.6%) patients died, 10 (4.9%) underwent limb amputation, and 11 (5.4%) new TECs occurred. Major bleeding occurred in 40 patients (19.5%) (seven during CPB surgery). Combining all prospective HAT trials (n = 403), after start of lepirudin treatment, the combined endpoint occurred in 82 patients (20.3%), with 47 deaths (11.7%), 22 limb amputations (5.5%), 30 new TECs (7.4%), and 71 (17.6%) major bleedings. Compared with the historical control group (log-rank test), the combined endpoint after start of treatment was reduced (29.7% vs. 52.1%, P = 0.0473), primarily because of reduction in new thromboses (11.9% vs. 32.1%, P = 0.0008). Mean lepirudin maintenance doses ranged from 0.07 to 0.11 mg kg(-1) h(-1). Major bleeding was more frequent in the lepirudin-treated patients (29.4% vs. 9.1%, P = 0.0148). CONCLUSIONS: The rate of new TECs in HIT patients is low after start of lepirudin treatment. The rate of major bleeding of 17.6% might be reduced by reducing the starting dose to 0.1 mg kg(-1) h(-1).

Development of resistance in Pseudomonas aeruginosa obtained from patients with cystic fibrosis at different times.

OBJECTIVE: Determination of the extent of changes in quantitative resistance in Pseudomonas aeruginosa isolates from patients with cystic fibrosis over a period of approximately 2 years. METHODS: Three hundred and ninety nine isolates of P. aeruginosa collected from 34 pediatric patients in the period between April 1994 and April 1996 were investigated. During the 2 years the children were treated with a combination of a betalactam and an aminoglycoside, approximately every 3 months. In between they received ciprofloxacin orally, when required. The minimal inhibitory concentrations (MICs) of 38 clones of P. aeruginosa defined by different patterns in macrorestriction analysis (pulse field gel electrophoresis, PFGE) were established for 12 antibiotics: gentamicin, amikacin, tobramycin, ciprofloxacin, levofloxacin, moxifloxacin, trovafloxacin, imipenem, meropenem, ceftazidime, cefepime, and piperacillin by means of broth microdilution tests according to DIN 58940. RESULTS: Twenty-four of the 38 clones developed increased MIC values during the time of observation especially for aminoglycosides and quinolones. Comparatively less affected were ceftazidime, imipenem and meropenem. An association between the number of the intravenous treatment courses and the increase of the MIC values could not be verified. CONCLUSIONS: A trend towards an increase of the MICs against antipseudomonal agents was observed over a limited period of time. It is necessary to prevent this development possibly by employing suitable combinations of antibiotics and the introduction of new substances.

[Experiences with enteral nutrition of patients with cystic fibrosis (CF) via a percutaneous endoscopic gastrostomy (PEG)]. / Erfahrungen mit der enteralen Ernährung von Patienten mit zystischer Fibrose (CF) über eine endoskopisch kontrollierte Gastrostomie (PEG).

BACKGROUND: We wanted improve the nutritional status of patients with cystic fibrosis with enteral feeding via a percutaneous endoscopic gastrostomy (PEG). PATIENTS AND METHODS: In a period of 8 years 11 patients underwent a percutaneous endoscopic gastrostomy (PEG), 4 males and 7 females, in the median 14,9 years of age (7,4/20,8). So far we overlook a median duration of enteral feeding therapy of 19,5 months (10/53). MAIN RESULTS: In 9 of the 11 patients we found a distinct increase of the predicted anthropometrical values,e.g. the weight for height value increased statistically significant in the first 3 months by 10,3 % from 84,7 % to 95,5 % and showed a further increase to 97,8 % after 10 months of nocturnal enteral feeding (p < 0,05). The predicted values of the lung function got stabilized too, with an increase by 9 % of the FEV1 and 3 % of the vital capacity after 10 months. Here was no statistically significance found. In one patient with a poor social-economic background and a lack of compliance the PEG had to be removed surgically because of an abscess formation. Another patient developed an acute gastric ulcer which responded very well onto conservative therapy. In the other patients there were no further complications. CONCLUSION: We can conclude that in the treatment of patients with cystic fibrosis showing an unsatisfying nutritional status the long-term nocturnal enteral feeding via a PEG is a good and well tolerated method. The best results we achieved when the gastrostomy was placed at an early state of the disease. That's why we demand an early mentioning of this option of enteral feeding to the patients and their families since the involved mostly need a long time for their decision for that invasive procedure.

Epidemiologic characterization of Pseudomonas aeruginosa in patients with cystic fibrosis.

OBJECTIVE: To determine persistence and variability of colonization with Pseudomonas aeruginosa in cystic fibrosis patients over long time periods, and to look for possible cross-colonization. METHODS: In total, 469 Pseudomonas aeruginosa isolates were obtained from 30 patients during the period from April 1994 to April 1996. The sources were mainly sputum and a few deep throat swabs. All grown strains dissimilar in macromorphology were processed separately. Typing with PFGE was carried out by contour-clamped homogeneous electric field electrophoresis. Genomic DNA was subjected to the rare-cutting restriction enzyme SpeI. For pyocin typing, the procedure described by Fyfe was applied. RESULTS: After typing with PFGE, we observed 40 restriction profiles. Eighteen different pyocin types were found. The most frequent pyocin type was type 3, followed by types 1 and 5. Twenty-two patients were persistently colonized by one clone specific and different for each patient, and four were co-colonized by a second clone also different for each of these patients. Cross-colonization had apparently been rare in the cystic fibrosis center of Leipzig. CONCLUSIONS: Typing with PFGE is well suited for detailed investigations of colonization with Pseudomonas aeruginosa in cystic fibrosis patients. Pyocin typing can provide additional information for epidemiologic purposes.

Fatty acids and glycerol or lactate are required to induce gluconeogenesis from alanine in isolated rabbit renal cortical tubules.

In isolated rabbit renal cortical tubules, glucose synthesis from 1 mM alanine is negligible, while the amino acid is metabolized to glutamine and glutamate. The addition of 0.5 mM octanoate plus 2 mM glycerol induces incorporation of [U-14C]alanine into glucose and decreases glutamine synthesis, whereas oleate and palmitate in the presence of glycerol are less potent than octanoate. Gluconeogenesis is also significantly accelerated when glycerol is substituted by lactate. In view of an increase in 14CO2 fixation and elevation of both cytosolic and mitochondrial NADH/NAD+ ratios, the activation of glucose formation from alanine upon the addition of glycerol and octanoate is likely due to (i) stimulation of pyruvate carboxylation, (ii) increased availability of NADH for glyceraldehyde-3-phosphate dehydrogenase and (iii) elevation of mitochondrial redox state causing a diminished provision of ammonium for glutamine synthesis. The induction of gluconeogenesis in the presence of alanine, glycerol and octanoate is not related to cell volume changes. The results presented in this paper show the importance of free fatty acids and glycerol for regulation of renal gluconeogenesis from alanine. The possible physiological significance of the data is discussed.

Importance of glutamate dehydrogenase stimulation for glucose and glutamine synthesis in rabbit renal tubules incubated with various amino acids.

The effect of 2-aminobicyclo[2.2.1]heptan-2-carboxylic acid (BCH), an L-leucine nonmetabolizable analogue and an allosteric activator of glutamate dehydrogenase, on glucose and glutamine synthesis was studied in rabbit renal tubules incubated with alanine, aspartate or proline in the presence of glycerol and octanoate, i.e. under conditions of efficient glucose formation. With alanine+glycerol+octanoate the addition of BCH resulted in a stimulation of alanine and glycerol consumption, accompanied by an increased glucose, lactate and glutamine synthesis. In contrast, when alanine was substituted by either aspartate or proline, BCH altered neither glucose formation nor glutamine and glutamate synthesis, while an accelerated glycerol utilization was accompanied by a small increase in lactate production. In view of the BCH-induced changes in intracellular metabolite levels the acceleration of gluconeogenesis by BCH in the presence of alanine+glycerol+octanoate is probably due to (i) increased uptake of alanine via alanine aminotransferase, (ii) stimulation of phosphoenolpyruvate carboxykinase, a key-enzyme of gluconeogenesis, (iii) rise of glucose-6-phosphatase activity, as well as (iv) activation of the malate-aspartate shuttle resulting in an augmented glycerol utilization for lactate and glucose synthesis.

Ketone bodies activate gluconeogenesis in isolated rabbit renal cortical tubules incubated in the presence of amino acids and glycerol.

In isolated rabbit renal kidney-cortex tubules 2 mM glycerol, which is a poor gluconeogenic substrate, does not induce glucose formation in the presence of alanine, while it activates gluconeogenesis on substitution of alanine by aspartate, glutamate or proline. The addition of either 5 mM 3-hydroxybutyrate or 5 mM acetoacetate to renal tubules incubated with alanine + glycerol causes a marked induction of glucose production associated with inhibition of glutamine synthesis. In contrast, the rate of the latter process is not altered by ketones in the presence of glycerol and either aspartate, glutamine or proline despite the stimulation of glucose formation. Acceleration of gluconeogenesis by ketone bodies in the presence of amino acids and glycerol is probably due to (i) stimulation of pyruvate carboxylase activity, (ii) activation of malate-aspartate shuttle as concluded from elevated intracellular levels of malate, aspartate and glutamate, as well as (iii) diminished supply of ammonium for glutamine synthesis from alanine resulting from a decrease in glutamate dehydrogenase activity.

Opposite effects of polyamines on glutamate deamination in isolated renal tubules and permeabilized kidney cortex mitochondria of rabbit.

The effect of polyamines on glutamate deamination has been studied in both isolated tubules and permeabilized kidney cortex mitochondria of rabbit. Spermine, spermidine and putrescine resulted in a decrease of ammonium release in isolated renal tubules incubated with glutamate in the presence of MSO and AOA, inhibitors of glutamine synthetase and aminotransferases, respectively. This was not due to the inhibition of glutamate transport across renal tubular membranes since transport of [14C]glutamate into brush border membranes vesicles was not decreased by polyamines. In contrast, polyamines stimulated glutamate deamination in permeabilized mitochondria. This effect was additive to the action of ADP, an allosteric activator of glutamate dehydrogenase. Since these compounds decreased both glutamate-induced mitochondrial swelling as well as [14C]glutamate accumulation in mitochondria, the inhibitory effect of polyamines on glutamate deamination in renal tubules might be due to a diminished glutamate transport across the mitochondrial membrane.

Hemiballismus as a presenting sign of hyperglycemia.

A 53-year-old man arrived at the emergency department after the onset of progressive hemiballismus. This movement disorder was the only manifestation of his hyperglycemic state. Prompt recognition of the association of unusual movement disorders with nonketotic hyperglycemia will allow for prompt treatment.

Glycerol and lactate induce reciprocal changes in glucose formation and glutamine production in isolated rabbit kidney-cortex tubules incubated with aspartate.

In renal tubules isolated from fed rabbits, 1 mM aspartate is mainly utilized for production of glutamine, glutamate, alanine, and serine, while it is not used for glucose synthesis. However, the addition of either 2 mM glycerol or 2 mM lactate, which are poor gluconeogenic substrates in renal tubules, results in acceleration of both glucose formation and incorporation of [14C]aspartate into glucose by several fold, accompanied by about a twofold decrease in glutamine synthesis and marked accumulation of glutamate and alanine. Ammonium release in renal tubules incubated with aspartate in the presence of methionine sulfoximine, an inhibitor of glutamine synthetase, is also decreased on the addition of glycerol and lactate by about two- and threefold, respectively. Since intracellular [glyceraldehyde 3-phosphate]/[3-phosphoglycerate], [glycerol 3-phosphate]/[dihydroxyacetone phosphate], [lactate]/[pyruvate], and intramitochondrial [glutamate]/[2-oxoglutarate] x [NH4+] ratios are increased in comparison with control values determined with aspartate alone, it is likely that the stimulatory effect of lactate and glycerol on glucose formation from aspartate may be due to (i) an increased availability of reducing equivalents in the cytosol resulting in an enhancement of glyceraldehyde-3-phosphate dehydrogenase activity and (ii) elevation of the mitochondrial NADH/NAD- ratio causing a decrease in glutamate dehydrogenase activity resulting in a diminished glutamine synthesis and enhanced provision of carbon skeleton of aspartate for gluconeogenesis. Stimulation of glucose formation in the presence of 1 mM aspartate + glycerol is not related to cell volume changes. However, an increase for about 30% of intracellular water space induced by 10 mM aspartate + glycerol is accompanied by both diminished gluconeogenesis and enhanced glutamine synthesis, compared with values measured with 1 mM aspartate plus glycerol.

Effect of polyamines on glutamate dehydrogenase within permeabilized kidney-cortex mitochondria and isolated renal tubules of rabbit.

The effect of polyamines on glutamate dehydrogenase [L-glutamate: NAD(P) oxidoreductase (deaminating) [EC 1.4.1.3]) activity has been studied in both permeabilized kidney-cortex mitochondria and isolated renal tubules of rabbit. Spermidine was the most potent inhibitor of glutamate synthesis in permeabilized mitochondria resulting in about 80% decrease of the enzyme activity at 5 mM concentration. Putrescine, alpha-monofluoromethylputrescine (MFMP) and (R,R)-delta-methyl-alpha-acetylenic-putrescine (MAP) were more efficient than spermine. The inhibitory action of polyamines was potentiated by an elevated NADH content in the reaction mixture. Increasing concentrations of either NH4Cl, KCl or NaCl in the incubation medium resulted in a decrease of polyamine-induced inhibition of the enzyme activity, indicating that monovalent cations can compete with polyamines for the binding site at glutamate dehydrogenase. The inhibitory action of spermidine on glutamate synthesis was abolished by 2 mM ADP or 10 mM L-leucine, allosteric activators of the enzyme, as well as on the addition of either oxalate or sulphate at 20 mM concentrations. Spermidine did not affect glutamate formation when NADH was substituted by NADPH, suggesting an importance of the NADH binding to the inhibitory site of the enzyme for a decrease of reductive amination of 2-oxoglutarate by polyamine. Although spermidine did not influence glutamate deamination in the presence of NAD+, it stimulated this process by about 70% when NAD+ was substituted by NADP+. In the presence of ADP the stimulatory effect of polyamine was not significant. The data indicate that in permeabilized rabbit kidney-cortex mitochondria the effect of polyamines on both glutamate formation and glutamate deamination via the reaction catalysed by glutamate dehydrogenase is dependent upon the coenzyme utilized by the enzyme. In the presence of NADH their inhibitory effect on the glutamate formation may be alleviated by allosteric activators of the enzyme, and concentrations of potassium, sodium, sulphate and oxalate. In isolated rabbit renal tubules incubated with 5 mM methionine sulfoximine and aminooxyacetate, in order to inhibit glutamine synthetase and aminotransferases, respectively, 5 mM spermidine decreased glutamate formation by about 30%, while putrescine and spermine did not significantly diminish the enzyme activity. In the presence of octanoate glutamate formation was reduced by about 30% by naturally occurring polyamines as well as MFMP and MAP, indicating that under these conditions NADH rather than NADPH is utilized as the coenzyme. In view of these data it is possible to suggest that polyamines may be of importance to control glutamate dehydrogenase activity under physiological conditions.

Differential in vivo and in vitro effect of gentamicin on glutamate synthesis and glutamate deamination in rabbit kidney-cortex tubules and mitochondria.

The effect of gentamicin on both glutamate synthesis and glutamate deamination was studied in kidney-cortex mitochondria and tubules isolated from both control and gentamicin-treated animals. In kidney-cortex mitochondria which were permeabilized in order to make a free access of substrates and antibiotic to the glutamate dehydrogenase, gentamicin appeared to be a very potent inhibitor of glutamate synthesis, resulting in about 60% decrease of the enzyme activity at 5 mM concentration. Other aminoglycoside antibiotics decreased the enzymatic activity, in the following order: gentamicin > neomycin = tobramycin = kanamycin > biodacyna > amikacin > streptomycin. This, in principle, corresponds to their known nephrotoxic potential observed in vivo. The inhibitory action of antibiotics was abolished by neither ADP nor leucine, allosteric activators of glutamate dehydrogenase. Surprisingly, gentamicin did not decrease the rate of ammonia formation from glutamate when added to both renal tubules and mitochondria isolated from control rabbits. This indicates that the antibiotic exerts its inhibitory effect on glutamate dehydrogenase activity in the direction of glutamate synthesis only. In contrast, the rate of both glutamate deamination and glutamate synthesis was about 40% lower in renal tubules and mitochondria isolated from kidney-cortex of animals which were given antibiotics for 10 days. In view of these results it seems that (i) the depression of ammoniagenesis in gentamicin-treated animals may be due to a decrease of glutamate dehydrogenase content and (ii) under conditions in vitro the aminoglycoside inhibits the enzyme activity in the direction of glutamate synthesis while it does not affect the glutamate deamination.

Recovery of impaired gluconeogenesis in kidney-cortex tubules of gentamicin-treated rabbits.

Rabbits were given gentamicin over a period of 10 days. At 1, 3, 5 and 10 days renal proximal tubules were isolated and glucose synthesis from several substrates was measured. A relationship between the inhibition of renal gluconeogenesis, accompanied by a decline of both pyruvate carboxylase and phosphoenopyruvate carboxykinase (PEPCK) activities, and an increased gentamicin level in kidney-cortex was noticed after 5 days of therapy. Both the rates of glucose formation from various substrates as well as pyruvate carboxylase and the cytosolic PEPCK activity recovered fully within 3 weeks after cessation of antibiotic treatment while an increase of activity of the mitochondrial PEPCK occurred during chronic administration of the drug for 10 days. It is concluded, that gentamicin-induced inhibition of gluconeogenesis is one of the events occurring during complex action of this drug on renal cortex.

The effect of various aminoglycoside antibiotics on glycogen phosphorylase activity in liver and kidney medulla of rabbit.

Glycogen phosphorylase activity in both liver and kidney medulla of rabbit was stimulated in the presence of caffeine by various aminoglycoside antibiotics in the following rank order: gentamicin greater than neomycin greater than amikacin = kanamycin greater than or equal tobramycin, while streptomycin did not affect the enzyme activity. In contrast, in the presence of AMP, the stimulatory action of antibiotics was not observed. Since in the gentamicin-treated rabbits stimulation of glycogen phosphorylase activity by about 30% in both liver and kidney medulla was accompanied by a decrease of liver glycogen content by about 60% it is likely that a decline in liver glycogen level following antibiotic treatment is due to an increased glycogen phosphorylase activity.