Diagnostic and prognostic value of brain natriuretic peptide (BNP) concentrations in very elderly heart disease patients: specific geriatric cut-off and impacts of age, gender, renal dysfunction, and nutritional status.

Confirming the presence of heart failure (HF) in geriatric patients is made difficult by the overlapping symptoms with other diseases and by limited access to investigative techniques such as echography, and the clinical signs are either non-constant or difficult to interpret. In this context, BNP measurement could prove highly useful. We determined a cut-off value of BNP for diagnosing HF in geriatric patients and gauged its predictive power in terms of cardiovascular events, dependence and death within a 6-month timeframe. This clinical and biological study was performed in patients, 44 women and 20 men, age>65 years with suspected HF hospitalized in the geriatric unit at Emile-Roux hospital. Echography was performed at baseline examination. BNP concentrations were determined at baseline examination and at 2 and 6 months later. Renal function was assessed via the Cockroft-Gault formula. Nutritional status was assessed using the geriatric nutritional risk index (GNRI). Final reference diagnosis was established by both cardiologist and geriatrician. The diagnostic value of BNP was assessed by area under the ROC curve. The average age of the 64 patients was 84.3±7.4 years. The final diagnosis was HF in 26 patients (41%). A BNP<129pg/ml had a negative predictive value of 90% (accuracy 80%) for excluding the diagnosis of HF. BNP values were predictive of cardiovascular events over a 2-month timeframe in patients with HF and over a 6-month timeframe in the global population. BNP values were not predictive of mortality in patients with or without HF. BNP testing should help to differentiate pulmonary from cardiac etiologies of dyspnea, but a specific cut-off point has to be used in geriatric settings, mainly for patients presenting nutritional and renal dysfunctions.

Is biolectrical impedance analysis a tool at bedside, during heat waves to assist geriatricians with discriminative diagnosis of hypertonic dehydration?

OBJECTIVES: To assess BIA data given by Analycor 3 and some bio-impedance equations to assist geriatricians with discriminative diagnosis of hypertonic dehydration, during heat waves. DESIGN: Prospective study: a dehydrated patients group has been compared with a randomised control group. SETTING: The study was carried out in a French geriatric department, in the Emile Roux geriatric hospital. PARTICIPANTS: 36: six men and twelve women in each group. MEASUREMENTS: The most valuable clinical indicators of dehydration severity were recorded and scored. BIA measurements were performed with an Analycor 3 analyzer; TBW was calculated from impedances at 50 and 100 kHz, ECW from impedance at 5 kHz; Calculations were made also with formula described in the literature, validated in healthy or in institutionalised elderly subjects. RESULTS: TBW and ECW values were always lower in dehydrated group than in control group, but without significance, whatever the applied formula; however ICW values calculated with "manufacturers equations" significantly decreased in dehydrated group. Data given by the analyzer used in this study, as well as BIA age specific equations discriminated the severely hypertonic dehydrated patients sub-group, but not the mildly hypertonic dehydrated patients sub-group. CONCLUSION: The BIA data given by the analyzer used in this study assist geriatricians at bedside with discriminative diagnosis of hypertonic dehydration, especially in severe hypertonic dehydration, but data given by the analyzer used in this study, as well as age specific equations are sometimes in poor agreement with clinical and biological parameters usually selected to assess dehydration, in mildly dehydrated patients.

Cytokine-mediated inhibition of ketogenesis is unrelated to nitric oxide or protein synthesis.

Cytokines play an important role in the lipid disturbances commonly associated with sepsis. Ketogenesis is inhibited during sepsis, and tumor necrosis factor alpha (TNF alpha) and interleukin-6 (IL-6) have been suggested to mediate this impairment, irrespective of the ketogenic substrate (fatty acid or branched chain ketoacid). However, the underlying mechanism of cytokine action is still unknown. First we investigated the possible role of the induction of nitric oxide (NO) synthesis, using rat hepatocyte monolayers. Hepatocytes were incubated for 6 h, with either alpha -ketoisocaproate (KIC) (1 mM) or oleic acid (0.5 mM) in the presence or absence of TNF alpha (25 microg/L) and IL-6 (15 microg/L). In some experiments, cells were incubated with NO synthase (NOS) inhibitors. The ketone body (beta -hydroxybutyrate and acetoacetate) production and nitrite production were measured in the incubation medium. Our results indicated no involvement of nitric oxide in the inhibitory action of cytokines on ketogenesis. Secondly, we showed that cycloheximide (10(-4)M) did not counteract the cytokine-mediated ketogenesis decrease; hence, the effects of cytokines on ketogenesis are not protein synthesis-dependent. The cytokine-mediated inhibition of ketogenesis is therefore unrelated to either NO production or protein synthesis.

Should a single centre for the assay of biochemical markers of nutritional status be mandatory in multicentric trials?

Clinical trials to identify patients at risk and to assess new therapeutic agents in the nutritional field are often single-site. The principal advantage of mounting a multicentric trial is that patient accrual is much quicker. Albumin, transthyretin, and C-reactive protein are frequently used biochemical markers of nutritional and inflammation status. However, the different techniques, reagents, and calibrators used to measure these markers introduce wide variations in values among laboratories. This study was carried out as part of a prospective multicentric study in chronic respiratory disease patients to evaluate variability and comparability of results among laboratories for these biochemical markers, and to determine whether centralization is necessary. Thirty enrolled laboratories provided their own range of reference values for those proteins a nd were then requested to process two control samples C1 and C2 blind. The results showed a broad dispersion of values for albumin and transthyretin. In 7% of laboratories, results of albumin for C2 (mean, all techniques: 39.1+/-3 g/l) were <35 g/l, the threshold value indicating a potential risk of malnutrition. When only laboratories using immunonephelemetry were considered, the results were satisfactory (CV<10% for all proteins). Given the possible incorrect classification of patients at risk, measurement should be made per site only if all participants use an immunonephelometric method. Otherwise, a centralizing assay of these biological markers should be considered.

Prevention of proteolysis in cold-stored rat liver by addition of amino acids to the preservation solution.

BACKGROUND: One process identified as detrimental in liver preservation is proteolysis. METHODS: We tested the effects of adding antiproteolytic amino acids (L-alanine, L-glutamine, L-histidine, L-leucine, L-methionine, L-phenylalanine, L-proline, L-tryptophan) to the preservation medium, in a model of reperfusion of 24 h cold-stored rat livers. RESULTS: During the preservation period, antiproteolytic amino acids inhibited the proteolysis observed in stored livers as shown by branched-chain amino acid fluxes, which switched from release to uptake. During reperfusion, cold storage of lives without the addition of antiproteolytic amino acids resulted in a decrease in the total amino acid and branched-chain amino acid uptake and a lower perfusion flow rate. The addition of antiproteolytic amino acids during liver storage resulted in the maintenance of total amino acid and branched-chain amino acid uptake and a significant improvement in the perfusion flow rate during reperfusion. CONCLUSIONS: The presence of antiproteolytic amino acids in the preservation medium might be of interest in improving hepatic graft viability in transplantation.

Branched-chain keto-acids and pyruvate in blood: measurement by HPLC with fluorimetric detection and changes in older subjects.

BACKGROUND: Measurement of keto-acids is important in various clinical situations. The aim of the present work was to develop a rapid HPLC method for the determination of keto-acids in human serum and to assess the concentrations of these acids in young adults and institutionalized elderly adults. This method was applied to the determination of blood keto-acid concentrations of young adults and institutionalized elderly people, divided into age groups METHODS: Four keto-acids (alpha-ketoisocaproate, alpha-ketoisovalerate, alpha-keto-beta-methylvalerate, and pyruvate) were derivatized with o-phenylenediamine to give fluorescent derivatives. After the sample preparation step (75 min to prepare 20 samples), the derivatives were separated chromatographically on a reversed-phase column using a binary gradient. RESULTS: The fluorometric detection of the four keto-acids was rapid, <12 min. The method is repeatable and reproducible: the CVs were <6% and <11%, respectively, for each of the keto-acids. We found no significant difference between males and females. Concentrations of the branched-chain keto-acids decreased after age 60 years, especially alpha-ketoisocaproate, which decreased approximately 40%. CONCLUSIONS: The proposed method allows rapid and reliable measurement of keto-acids. The data demonstrate that changes in branched-chain keto-acids concentrations in serum occur with age.

Abnormalities in branched-chain amino acid metabolism in cirrhosis: influence of hormonal and nutritional factors and directions for future research.

Plasma branched-chain amino acid (BCAA) levels are decreased in patients with liver cirrhosis, owing to an increase in BCAA tissue uptake and/or catabolism and a decrease in BCAA production from proteins. Non-specific factors such as malnutrition worsen this picture. Studies of BCAA fluxes and protein turnover in cirrhotic patients have given conflicting results due to patient heterogeneity, differences in method and bias in the expression of results. In well compensated cirrhosis, muscle wasting is moderate and probably due more to decreased protein synthesis than to increased protein catabolism. Hyperinsulinemia has been suggested as the main cause of decreased BCAA levels, by increasing BCAA uptake in muscle and additionally in adipose tissue. However, as depletion of fat stores is frequent in cirrhosis, this effect is certainly quantitatively weak. Also, there is no correlation between state of hyperinsulinemia and decrease in BCAA levels. An effect of cytokines (IL1 and TNF) on muscle BCAA catabolism is a possibility. Until recently, the contribution of the liver to abnormal BCAA metabolism has been underestimated. In cirrhotic liver an increase in liver transamination of branched-chain keto acids (BCKAs) has been suggested and may result from inhibition of liver BCKA dehydrogenase. A modification of protein turnover in cirrhotic liver must be also considered. Lastly, the contribution of non-hepatocyte liver cells, which are activated in cirrhosis, remains to be assessed.

TNF-alpha and IL-6 synergistically inhibit ketogenesis from fatty acids and alpha-ketoisocaproate in isolated rat hepatocytes.

BACKGROUND: During sepsis, lipid metabolism is shunted toward triacylglycerol synthesis and hepatic lipogenesis. A decrease in ketogenesis from free fatty acids also is observed, probably mediated by cytokines involved in host response to infection. Whether such an inhibition of ketogenesis occurs with other ketone body precursors such as ketoacids is not known. The aim of this study was to determine the effects of tumor necrosis factor alpha (TNF-alpha) and interleukin 6 (IL-6) on hepatic ketone body production from octanoic acid, a medium-chain fatty acid, and from alpha-ketoisocaproate (KIC), the ketoanalogue of leucine. METHODS: The experiments were conducted in cultured hepatocytes isolated from 24-hour-fasted Sprague-Dawley rats. Hepatocyte monolayers were incubated for 6 hours, with either KIC or octanoic acid (1 mmol/L), in the presence of glucagon and TNF-alpha (25 micro/L) IL-6 (15 microg/L) and/or IL-6. Acetoacetate, beta-hydroxybutyrate, and free fatty acids were determined in culture medium by enzymatic methods and KIC was measured by high-performance liquid chromatography. RESULTS: KIC and octanoic acid uptake by hepatocytes was 79% and 92%, respectively, over 6 hours, and cytokines had no influence. However, TNF-alpha and IL-6 caused inhibition of ketogenesis from alpha-ketoisocaproate (5.6% +/- 2.3% and 4.4% +/- 3.0%, respectively), and from octanoic acid (7.9% +/- 2.9%, 5.7% +/- 3.2%, respectively). In addition, when the two cytokines were present together in the culture medium, the inhibition was enhanced (inhibition of ketogenesis from KIC: 14.0% +/- 4.8%; from octanoic acid: 11.6% +/- 3.4%). CONCLUSIONS: In our experimental conditions, cytokines mediate an inhibition of ketogenesis; this process could be explained by a direct effect of cytokines on metabolic pathways of octanoic acid and KIC oran indirect effect by modification of the mitochondrial redox state.

Markers of oxidative stress in fit, health-conscious elderly people living in the Paris area. The Research Group on Ageing (GERBAP)

Lipid peroxidation index and antioxidant indicators were assessed by biochemical means in 193 healthy elderly volunteers (103 men and 90 women), ages 70-89 y and living freely in the Paris area. Lipid peroxidation index was in the same range as in young adults. Zinc, copper, and selenium levels were satisfactory and similar to those in young adults, though the range of copper values tended to be higher. Copper and selenium levels were higher in elderly women than in men. However, for selenium values this sex-related difference disappeared in elderly volunteers > 75 y. Copper-zinc-superoxide dismutase and glutathione peroxidase activities were similar to those in young adults, with no influence of sex or age. Vitamin E and total carotene, closely related to cholesterol levels, were satisfactory. Our findings show that markers of oxidative stress are not influenced by old age when good health and nutritional status are preserved, as in this selected population.

[Reference intervals and biological profile in a group of healthy elderly population in the Paris region]. / Intervalles de référence et profil biologique d'une population de sujets âgés "en bonne santé" habitant la région parisienne. (Group d'évaluation et de recherche des biologistes de l'APHP).

The superimposition of pathological processes on ageing-related metabolic changes makes the interpretation of laboratory data difficult in the elderly. Therefore, in order to establish reference values of anthropometric, hematological and biochemical variables, we have carefully selected fit, health-conscious elderly subjects on the basis of clinical and biological criteria. We observed a trend for a wider range of values than in young adults. For some variables, the values were shifted down (eg: albumin, vitamin D) or up (eg: glucose, urea, cholesterol, ferritin), as a result of slow metabolic changes or progressive functional decline of different organs. The high prevalence of hypovitaminosis D was worthy of note, particularly in women, suggesting a high risk of deficiency.

Metabolism of alpha-ketoisocaproic acid in isolated perfused liver of cirrhotic rats.

To determine the hepatic fate of alpha-ketoisocaproate (KIC) in cirrhosis, six groups of isolated rat livers were perfused with 0, 0.5, 1 (with or without alpha-[1-14C]KIC), 2, and 5 mM KIC; control livers from healthy rats were studied in parallel under similar conditions. KIC was rapidly removed by the normal livers, whereas uptake was lower in the cirrhotic livers at all concentrations tested (at 2 mM, 4.04 +/- 0.33 vs. 6.32 +/- 0.58 mumol/min; P < or = 0.05). The transamination pathway, evaluated by leucine exchanges, was more important in the cirrhotic livers (25.4 vs. 6.8% in controls at 2 mM). The incorporation of alpha-[1-14C]KIC in proteins of cirrhotic liver was increased compared with controls (0.25 +/- 0.04% of alpha-[1-14C]KIC was incorporated in proteins excreted in perfusate vs. 0.20 +/- 0.04 in controls; P < or = 0.05). In addition, a line of evidence suggests that glutamine rather than glutamate is the N donor for leucine synthesis from KIC. The decarboxylation pathway evaluated by beta-hydroxybutyrate production and by 14CO2 release from alpha-[1-14C]KIC was reduced, respectively, by 40-85% (according to KIC dose) and by 24% at 90 min in cirrhotic livers compared with healthy livers. These results indicate a dramatic modification of KIC metabolism in the cirrhotic liver; its uptake by the liver is decreased and its incorporation into proteins is increased via an enhancement of transamination to leucine, probably as a consequence of an inhibition of branched-chain keto acid dehydrogenase.

Extensive laboratory assessment of nutritional status in fit, health-conscious, elderly people living in the Paris area. Research Group on Aging.

OBJECTIVE: Nutritional status-related biological indexes were measured in fit, health-conscious elderly subjects in order to establish reference values for people over 70 years. SUBJECTS: 103 men and 90 women aged 70-89 years living freely in the Paris area volunteered to participate. METHODS: Nutritional status was assessed by anthropometric and biochemical methods. RESULTS: Serum protein and amino acid status was similar to that of young adults, with only 5.2% of the elderly subjects showing transthyretin concentrations < 0.20 g/L, as well as decreased essential amino acid levels. Iron status, assessed in terms of serum and erythrocyte ferritin levels, total iron binding capacity and erythrocyte protoporphyrin tended to be satisfactory, but iron depletion was detected in 8.8% of the subjects. Serum ferritin levels were elevated in 19.7% of the subjects. Folate and vitamin B12 status was satisfactory, while hypovitaminosis D was observed in 48.2% of cases. CONCLUSION: Our findings suggest that, in aging uncomplicated by disease, nutritional status is similar to that in younger adults, although the range of values tended to be wider, with a higher risk of certain nutrient deficiencies.

Assessment of the carbon tetrachloride-induced cirrhosis model for studies of nitrogen metabolism in chronic liver disease.

We evaluated the rat cirrhosis model obtained by repeated intraperitoneal administration of CCl4 (group C) with regard to biological and nutritional conditions in comparison to ad libitum (group AL) and pair-fed control rats. Cirrhotic rats were divided into two groups according to their clinical condition: group C1 (n = 4) represented those in good physical condition and group C2 those (n = 10) in poor physical condition. Autopsy indicated that rats in group C2 suffered from severe malnutrition as judged by body weight, carcass weight and the carcass/body weight ratio. However, all 14 treated rats presented the same micronodular cirrhosis and the same alterations in liver function, except for alkaline phosphatase activity (group C1: 110 +/- 63 IU/l, group C2: 259 +/- 110 IU/l; p < 0.05). In the cirrhosis groups, plasma levels of branched-chain amino acids (BCAA) and the BCAA/aromatic amino acid (AAA) ratio were significantly reduced, but values in groups C1 and C2 were not significantly different (BCAA/AAA: 1.9 +/- 0.9 in group C1, 1.5 +/- 0.8 in group C2, 2.8 +/- 0.3 in group AL; C1 and C2, vs. AL: p < 0.05). These alterations were similar to those observed in human cirrhosis and were not solely the result of reduced food intake, as indicated by the lack of difference between pair-fed and ad libitum-fed control rats.

Branched-chain amino acid metabolism in isolated perfused liver of cirrhotic rats.

We examined the possible contribution of the liver to the alterations in branched-chain amino acid (BCAA) metabolism in cirrhosis. The livers of male Sprague-Dawley rats with CCl4-induced cirrhosis were removed and placed in a recirculating perfusion system. Net amino acid uptake and release were determined over 55 min. Results were compared with those obtained with control animals, which were either pair-fed or fed ad libitum. Intrahepatic amino acid concentrations were determined at the end of the perfusion. The release of isoleucine and leucine was significantly lower in the cirrhotic livers than in the controls fed ad libitum. There was no difference between the cirrhotic and pair-fed groups with regard to the fluxes of the three BCAA. Intrahepatic concentrations of BCAA were reduced only in pair-fed controls. These results suggest that both cirrhosis and a low protein/calorie diet alter hepatic BCAA flux, but via different mechanisms. In cirrhosis, alterations could be due both to low food intake and to BCAA metabolism in non-parenchymal cells.

Effect of recombinant human interleukin 1ß (rhIL-1ß) on amino acid flux in the isolated perfused rat liver.

We studied the effect of recombinant human IL-1ß (rhIL-1ß) on hepatic amino acid (AA) flux in the isolated perfused rat liver model. Two experimental groups were used - a control group (n = 5) and a rhIL-1ß-treated group (n = 5). IL-1 was added to the perfusate in two successive boluses of 0.1µg and 0.9µg, respectively 35 min (final concentration 0.67 ng/ml) and 60 min (6 ng/ml) after beginning the perfusion. In the IL-1 treated group, a reduction in flux was observed for only three AA, alanine, phenylalanine and serine. Glucose and urea production in the IL-1-treated group was slightly but not-significantly lower than in the controls.rhIL-1ß thus has only minor direct effects on AA flux and gluconeogenesis in the liver and cannot therefore be held responsible for the increase in hepatic amino acid uptake during stress.