An increase in the redox state during reperfusion contributes to the cardioprotective effect of GIK solution

This study aimed at determining whether glucose-insulin-potassium (GIK) solutions modify the NADH/NAD(+) ratio during postischemic reperfusion and whether their cardioprotective effect can be attributed to this change in part through reduction of the mitochondrial reactive oxygen species (ROS) production. The hearts of 72 rats were perfused with a buffer containing glucose (5.5 mM) and hexanoate (0.5 mM). They were maintained in normoxia for 30 min and then subjected to low-flow ischemia (0.5% of the preischemic coronary flow for 20 min) followed by reperfusion (45 min). From the beginning of ischemia, the perfusate was subjected to various changes: enrichment with GIK solution, enrichment with lactate (2 mM), enrichment with pyruvate (2 mM), enrichment with pyruvate (2 mM) plus ethanol (2 mM), or no change for the control group. Left ventricular developed pressure, heart rate, coronary flow, and oxygen consumption were monitored throughout. The lactate/pyruvate ratio of the coronary effluent, known to reflect the cytosolic NADH/NAD(+) ratio and the fructose-6-phosphate/dihydroxyacetone-phosphate (F6P/DHAP) ratio of the reperfused myocardium, were evaluated. Mitochondrial ROS production was also estimated. The GIK solution improved the recovery of mechanical function during reperfusion. This was associated with an enhanced cytosolic NADH/NAD(+) ratio and reduced mitochondrial ROS production. The cardioprotection was also observed when the hearts were perfused with fluids known to increase the cytosolic NADH/NAD(+) ratio (lactate, pyruvate plus ethanol) compared with the other fluids (control and pyruvate groups). The hearts with a high mechanical recovery also displayed a low F6P/DHAP ratio, suggesting that an accelerated glycolysis rate may be responsible for increased cytosolic NADH production. In conclusion, the cardioprotection induced by GIK solutions could occur through an increase in the cytosolic NADH/NAD(+) ratio, leading to a decrease in mitochondrial ROS production.

Rapid reduction of liver steatosis in omega3-depleted rats injected with a novel lipid emulsion

The bolus intravenous administration of a novel medium-chain triglyceride: fish oil emulsion (MCT:FO) to normal subjects was recently found to increase within 60 min the amount of long-chain polyunsaturated omega3 fatty acids ( omega3) in platelet and leukocyte phospholipids and, hence, was proposed as a tool to prevent such pathological events as cardiac arrhythmia in selected patients who have to undergo urgent anesthesia and/or surgery. This study investigates whether other cells located outside the vascular bed may also benefit from this procedure for replenishing phospholipids with omega3. For such a purpose, the MCT:FO emulsion (1.0 ml) was injected into normal or omega3-depleted rats examined, one hour later, for the content and fatty acid pattern of liver triglycerides and phospholipids. Control experiments included the administration of saline or a medium-chain triglyceride:olive oil emulsion. The results reveal that the bolus intravenous injection of MCT:FO to the omega3-depleted rats resulted in the enrichment of liver phospholipids in omega3 and a marked reduction in hepatic steatosis. In conclusion, it is proposed that such a procedure may indeed allow a rapid supply of omega3 not only to circulating and vascular endothelial cells but also to extravascular cells, with a resulting correction of the biochemical and biophysical defects linked to a deficiency in these fatty acids.

Peripheral venous complications of a hyperosmolar (960 mOsm) nutritive mixture: The effect of heparin and hydrocortisone. A multicenter double-blinded random study in 98 patients

Peripheral intravenous nutrition with hyperosmolar solutions usually results in a high rate of venous complications. The aim of this multicenter double blind randomised study in 98 patients has been to measure: (a) tolerance by the peripheral veins being perfused with a protein-glucose-lipid nutritive mixture of 960 mOsm/l (group A, n = 33), (b) the protective effect of the additive to the nutritive mixture of either heparin: 1000 IU/1 (group B, n = 32) or heparin with hydrocortisone (5 mg/l) group C, n = 33). Tolerance by the veins was evaluated on a single vein site during a 48 h perfusion with 21 per day. The following complications: oedema, erythema, induration, thrombophlebitis led to the interruption of the perfusion. The rate of interruptions of perfusions for total venous complications and for thrombophlebitis has been respectively: at 24 h, in group A: 39 and 15%, in group B: 6 and 3%, in group C: 12 and 0%; at 48 h: in group A: 82 and 42%, in group B: 53 and 18%, in group C: 36 and 6%. Venous complication rates for 24 and 48 h were significantly lower in groups B and C (p<0.05) than in group A and there was no inter group difference between groups B and C. These results suggest that peripheral venous nutrition infusing 14.1 g of nitrogen and 8.5 MJ per day can be performed with a hyperosmolar solution of 960 mOsm/1, if that heparin be added to the nutritive mixture and the perfusion site be changed daily. Under these conditions the observed venous complications rate is equal to or less than 6% of cases.

Accelerated clearance of plasma triglycerides and free fatty acids in omega3-depleted rats

The present study aims mainly at exploring the effects of a severe depletion in polyunsaturated long-chain omega3 fatty acids upon the fate of circulating lipids. The plasma concentration and fatty acid pattern of triglycerides, diglycerides, free fatty acids, and phospholipids were measured in omega3-depleted and control rats injected intravenously one hour before sacrifice with either saline, a control medium-chain triglyceride:olive oil emulsion or a medium-chain triglyceride:fish oil emulsion recently found to rapidly increase the phospholipid content of C20:5omega3 and C22:6omega3 in different cell types. The estimated fractional removal rate of the injected triglycerides and the clearance of free fatty acids from circulation were both higher in omega3-depleted rats than in control animals. The injection of the lipid emulsions apparently inhibited intracellular lipolysis, this being least pronounced in omega3-depleted rats. The increased clearance of circulating triglycerides and unesterified fatty acids in omega3-depleted rats may favor the cellular accumulation of lipids. In turn, such an accumulation and the lesser regulatory inhibition of tissular lipolysis may match the increased clearance of circulating unesterified fatty acids and, hence, account for the lack of any significant difference in plasma unesterified fatty acid concentration between these and control animals.

High dietary sucrose triggers hyperinsulinemia, increases myocardial β-oxidation, reduces glycolytic flux and delays post-ischemic contractile recovery

Although the causal relationship between insulin resistance (IR) and hypertension is not fully resolved, the importance of IR in cardiovascular dysfunction is recognized. As IR may follow excess sucrose or fructose diet, the aim of this study was to test whether dietary starch substitution with sucrose results in myocardial dysfunction in energy substrate utilization and contractility during normoxic and post-ischemic conditions. Forty-eight male Wistar rats were randomly allocated to three diets, differing only in their starch to sucrose (S) ratio (13, 2 and 0 for the Low S, Middle S and High S groups, respectively), for 3 weeks. Developed pressure and rate x pressure product (RPP) were determined in Langendorff mode-perfused hearts. After 30 min stabilization, hearts were subjected to 25 min of total normothermic global ischemia, followed by 45-min reperfusion. Oxygen consumption, beta-oxidation rate (using 1-13C hexanoate and Isotopic Ratio Mass Spectrometry of CO2 produced in the coronary effluent) and flux of non-oxidative glycolysis were also evaluated. Although fasting plasma glucose levels were not affected by increased dietary sucrose, high sucrose intake resulted in increased plasma insulin levels, without significant rise in plasma triglyceride and free fatty acid concentrations. Sucrose-rich diet reduced pre-ischemic baseline measures of heart rate, RPP and non-oxidative glycolysis. During reperfusion, post-ischemic recovery of RPP was impaired in the Middle S and High S groups, as compared to Low S, mainly due to delayed recovery of developed pressure, which by 45 min of reperfusion eventually resumed levels matching Low S. At the start of reperfusion, delayed post-ischemic recovery of contractile function was accompanied by: (i) reduced lactate production; (ii) decreased lactate to pyruvate ratio; (iii) increased beta-oxidation; and (iv) depressed metabolic efficiency. In conclusion, sucrose rich-diet increased plasma insulin levels, in intact rat, and increased cardiac beta-oxidation and coronary flow-rate, but reduced glycolytic flux and contractility during normoxic baseline function of isolated perfused hearts. Sucrose rich-diet impaired early post-ischemic recovery of isolated heart cardiac mechanical function and further augmented cardiac beta-oxidation but reduced glycolytic and lactate flux.

Effects of permeability transition inhibition and decrease in cytochrome c content on doxorubicin toxicity in K562 cells

As mitochondria play a key role in the commitment to cell death, we have investigated the mitochondrial consequences of resistance to doxorubicin (DOX) in K562 cells. We found that the permeability transition pore (PTP) inhibitor cyclosporine A (CsA) failed to inhibit PTP opening in the resistant clone. Moreover, the Ca2+ loading capacity in the resistant clone was identical to that observed in the parent cells in the presence of CsA, suggesting that the PTP was already inhibited in a CsA-like manner in the resistant cells. In agreement with this proposal, the mitochondrial target of CsA cyclophilin D (CyD) decreased by half in the resistant cells. The levels of adenine nucleotide translocator, voltage anion-dependent channel, Bax, Bcl-2, Bcl-xL, AIF and Smac/Diablo, were similar in both cell lines, whereas cytochrome c content was divided by three in the resistant cells. Since P-glycoprotein inhibition did not restore DOX toxicity in the resistant cells, while DOX-induced cell death in the parent cells was prevented by either PTP inhibition or siRNA-induced decrease in cytochrome c content, we conclude that the inhibition of PTP opening and the decrease in cytochrome c content participate in the mechanism that makes K562 cells resistant to DOX.

Low rate of glucose 6-phosphate hydrolysis in liver cells is a physiological feature of non-diabetic wild sand rats (Psammomys obesus)

OBJECTIVE

In this study we have compared glucose metabolism and liver gluconeogenesis in wild adult desert gerbil Psammomys obesus fed with their natural halophilic plants and Wistar rats fed on a laboratory chow. Psammomys obesus is a natural model of insulin resistance when fed a rodent laboratory chow.

METHODS

Basal glucose and insulin were determined in plasma of fasting animals. Hepatocyte gluconeogenesis from lactate-plus-pyruvate was investigated in perifused hepatocytes by assessing simultaneously glucose synthesis rate and intracellular oxaloacetate, phosphoenolpyruvate, 3-phosphoglycerate, fructose 6-phosphate and glucose 6-phosphate (G6P) under true steady state conditions.

RESULTS

Fasting blood glucose (2.8 +/- 0.1 vs 4.8 +/- 0.4 mmol.L(- 1)) and plasma insulin concentration (129 +/- 14 vs 150 +/- 21 pmol.L(-1)) were significantly lower in Psammomys as compared to albino rats. Maximal gluconeogenic rate was also lower in Psammomys (2.3 +/- 0.3 vs 5.1 +/- 0.3 micromol x min(-1) x g dry cells(-1)). This effect was related to a slower hydrolysis of G6P.

CONCLUSION

A lower G6P hydrolysis in Psammomys as compared to wistar was the main difference between the two groups of liver cells. Such feature may represent the major metabolic adaptation permitting Psammomys to survive despite its severe restrictive natural conditions. Indeed, a low G6P hydrolysis allows an insulin resistance state, with a high lipogenic activity, but associated with low blood glucose. The rise in blood glucose occurring when Psammomys are fed with exogenous carbohydrates perturbs such delicate metabolic equilibrium, resulting thus in a diabetic state because of the deleterious effect of hyperglycemia.

Protective effects of recombinant growth hormone on intestinal mucosa in rats receiving abdominal radiotherapy

BACKGROUND AND AIMS

Radiation injury to the gut induces nutrient losses that compromise the body ability to adequately fight infection, heal wounds and recover from illness. Recombinant growth hormone (rhGH), is known to enhance anabolism, therefore, we tested the hypothesis that rhGH preserves whole body growth and trophism of the jejunum and ileum of irradiated rats.

METHODS

After acclimatization period, the rats were divided in three groups: (1). control rats (C), (2). rats irradiated with a single dose of 10 Gy (group A); (3). rats irradiated with a single dose of 5 Gy (Group B); after irradiation, rats were given subcutaneously (sc) saline or 0.25 or 0.50 mg rhGH/kg BW/d for the following 6 days. Body weight changes were recorded during this time. On day 6 post-radiation, rats were killed and small intestine mucosa dry and wet weights were measured, as well as mucosa protein content.

RESULTS

Group A rats lost body weight during the 6-day post-radiation period, regardless of rhGH treatment and dosage. rhGH was effective in preventing weight loss and normalizing growth in group B rats (saline 23.1+/-11.1, vs. controls P<0.05; rhGH: 35.0+/-10.0 g BW/d, vs. controls P = ns). Trophic effect of rhGH was observed on mucosa weight and mucosa protein content in rats irradiated with 5 Gy, but not in those receiving 10 Gy.

CONCLUSION

rhGH seems to normalize growth and mucosa protein content in irradiated rats. However, rhGH beneficial effects were observed only in rats receiving the lower dose of radiation.

Rotenone inhibits the mitochondrial permeability transition-induced cell death in U937 and KB cells

The permeability transition pore (PTP) is a mitochondrial inner membrane Ca(2+)-sensitive channel that plays a key role in different models of cell death. Because functional links between the PTP and the respiratory chain complex I have been reported, we have investigated the effects of rotenone on PTP regulation in U937 and KB cells. We show that rotenone was more potent than cyclosporin A at inhibiting Ca(2+)-induced PTP opening in digitonin-permeabilized cells energized with succinate. Consistent with PTP regulation by electron flux through complex I, the effect of rotenone persisted after oxidation of pyridine nucleotides by duroquinone. tert-butyl hydroperoxide induced PTP opening in intact cells (as shown by mitochondrial permeabilization to calcein and cobalt), as well as cytochrome c release and cell death. All these events were prevented by rotenone or cyclosporin A. These data demonstrate that respiratory chain complex I plays a key role in PTP regulation in vivo and confirm the importance of PTP opening in the commitment to cell death.

Metabolic and nutritional disorders in cardiac cachexia

Cardiac cachexia is divided into two types, i.e., the classic type, which occurs in patients with severe heart failure, and the nosocomial type, which develops in the postoperative state. Cardiac cachexia is due both to a decrease in nutrient intake (anorexia, malabsorption) and to specific metabolic alterations (hypercatabolism with increased energy expenditure, response to hypoxia, inflammatory status, etc). Among the various mechanisms involved in the pathogenesis of cachexia, cellular hypoxia has long been recognized. The chronic activation of the endogenous neurohormonal system is another specific feature of such patients; a striking relationship was found between cardiac cachexia and hormonal levels which correlate better than the classical parameters of cardiac failure severity. Finally, inflammatory syndrome has been known to occur frequently in patients with cardiac cachexia. Several studies have shown that tumor necrosis factor-alpha was significantly increased in cachectic patients and that chronic activation of the systemic immune response might be a common and unifying factor.

Allosteric activation of pyruvate kinase via NAD+ in rat liver cells

In isolated rat hepatocytes, it has previously been reported that a rise in the ATP content induces a proportional increase in cytosolic NAD+ concentration [Devin, A., Guérin, B. & Rigoulet, M. (1997) FEBS Lett. 410, 329-332]. This occurs under physiological conditions such as various substrates or different energetic states. To investigate the effect of a physiological rise in cytosolic [NAD+] per se on glycolysis and gluconeogenesis, an increase in [NAD+] induced by exogenous nicotinamide addition was obtained without a change in redox potential, ATP/ADP ratio and ATP concentration. Using dihydroxyacetone as substrate, we found that an increase in cytosolic [NAD+] decreases gluconeogenesis and enhances glycolysis without significant alteration of dihydroxyacetone consumption rate. These modifications are the consequence of an allosteric activation of pyruvate kinase via cytosolic NAD+ content. Thus, in addition to the well-known thermodynamic control of glycolysis by pyridine-nucleotide redox status, our study points to a new mechanism of glycolytic flux regulation by NAD+ concentration at the level of pyruvate kinase activity.

Factors influencing survival in hemodialysis patients aged older than 75 years: 2.5-year outcome study

The incidence of malnutrition is widely held to be greater in the elderly, but this specific factor has not been extensively studied in elderly dialysis patients. In a 30-month follow-up prospective study, we evaluated the role of nutrition on the outcome of 290 stable hemodialysis (HD) outpatients aged older than 75 years followed up in 20 French HD centers (167 men, 123 women; age, 79.8 +/- 4.2 years; previous time on dialysis, 41 +/- 38 months). On the same day in January 1996, predialysis and postdialysis blood samples were collected according to recommended procedures for dialysis quantification. Normalized protein catabolic rate, dialysis adequacy parameters, and estimation of lean body mass (LBM; expressed as observed/expected LBM values [obs/exp LBM]) were computed from predialysis and postdialysis urea and creatinine levels. Overall survival rates were 80% and 65% after 1 and 2 years of follow-up, respectively, and were significantly less in patients with the lower quartile of obs/exp LBM. In univariate analysis using the Cox proportional hazards model, survival was significantly influenced by age, albumin level, prealbumin level, body mass index, and diabetes, but not by sex, Kt/V, duration of dialysis, cholesterol level, hemoglobin level, or obs/exp LBM. In multivariate analysis, no variable remained significant. Cardiovascular mortality accounted for 52.1% of the patient deaths. We conclude that in elderly HD patients, malnutrition influences overall survival despite adequate dialysis treatment.

The mitochondrial consequences of uncoupling intact cells depend on the nature of the exogenous substrate

In isolated mitochondria the consequences of oxidative phosphorylation uncoupling are well defined, whereas in intact cells various effects have been described. Uncoupling liver cells with 2,4-dinitrophenol (DNP) in the presence of dihydroxyacetone (DHA) and ethanol results in a marked decrease in mitochondrial transmembrane electrical potential (DeltaPsi), ATP/ADP ratios and gluconeogenesis (as an ATP-utilizing process), whereas the increased oxidation rate is limited and transient. Conversely, when DHA is associated with octanoate or proline, DNP addition results in a very large and sustained increase in oxidation rate, whereas the decreases in DeltaPsi, ATP/ADP ratios and gluconeogenesis are significantly less when compared with DHA and ethanol. Hence significant energy wastage (high oxidation rate) by uncoupling is achieved only with substrates that are directly oxidized in the mitochondrial matrix. Conversely in the presence of substrates that are first oxidized in the cytosol, uncoupling results in a profound decrease in mitochondrial DeltaPsi and ATP synthesis, whereas energy wastage is very limited.

Role of Na+-K+-ATPase in insulin-induced lactate release by skeletal muscle

Hyperinsulinemia increases lactate release by various organs and tissues. Whereas it has been shown that aerobic glycolysis is linked to Na+-K+-ATPase activity, we hypothesized that stimulation by insulin of skeletal muscle Na+-K+-ATPase is responsible for increased muscle lactate production. To test this hypothesis, we assessed muscle lactate release in healthy volunteers from the [13C]lactate concentration in the effluent dialysates of microdialysis probes inserted into the tibialis anterior muscles on both sides and infused with solutions containing 5 mmol/l [U-13C]glucose. On one side, the microdialysis probe was intermittently infused with the same solution additioned with 2.10(-5) M ouabain. In the basal state, [13C]lactate concentration in the dialysate was not affected by ouabain. During a euglycemic-hyperinsulinemic clamp, [13C]lactate concentration increased by 135% in the dialysate without ouabain, and this stimulation was nearly entirely reversed by ouabain (56% inhibition compared with values in the dialysate collected from the contralateral probe). These data indicate that insulin stimulates muscle lactate release by activating Na+-K+-ATPase in healthy humans.

Acute hepatic steatosis complicating massive insulin overdose and excessive glucose administration

OBJECTIVE

To describe a case of acute hepatic steatosis due to excessive administration of glucose in the setting of massive insulin overdose, a complication which is rapidly and completely reversible if glucose infusion is rapidly tapered.

DESIGN

Case report, clinical.

SETTING

Intensive care unit, university hospital.

PATIENT

A single patient admitted to the ICU.

INTERVENTION

Intravenous glucose after insulin overdose.

MEASUREMENTS AND MAIN RESULTS

On the 3rd day, increases in transaminase (ASAT 420 IU/l, ALAT 610 IU/l), bilirubin (147 mmol/l) and lactate (6.8 mmol/l), a decrease in arterial pH (7.32) and slightly increased liver size on ultrasound examination suggested acute hepatic steatosis. Clinical and laboratory abnormalities resolved rapidly after discontinuation of excessive glucose infusions (1,400 g/day for 3 days).

CONCLUSIONS

Very large amounts of glucose after massive insulin overdose are potentially dangerous. Even though the fear of hypoglycemia-induced neurologic damage should be a constant preoccupation in this situation, glucose administration should be titrated on closely monitored blood glucose levels.

Influence of nutritional factors and hemodialysis adequacy on the survival of 1,610 French patients

Nutritional factors and dialysis adequacy are associated with outcome in hemodialyzed patients, but their relative contribution remains controversial, particularly when dialysis adequacy complies with current recommendations (Kt/V >1.2). Survival, clinical, and nutritional data from a cohort of prevalent 1,610 patients treated by hemodialysis in 20 centers in France have been collected over a 2.5-year period, from January 1996 to July 1998. Data including age, sex, cause of end-stage renal disease (ESRD), clinical outcome, time on dialysis, body mass index (BMI), blood levels of midweek predialysis albumin, prealbumin, and bicarbonate were analyzed. Normalized protein catabolic rate (nPCR), dialysis adequacy parameters, and estimation of lean body mass (LBM) from creatinine generation were computed from pre- and postdialysis urea and creatinine levels. The characteristics of the patients were as follows: age 59.6 +/- 16.5 years, 58.8% males, 11% of diabetics, time on dialysis 63.2 +/- 64.5 m. Weekly dialysis time was 12.18 +/- 1.78 hrs, Kt/V 1.34 +/- 0.34, nPCR 1.10 +/- 0.35 g/kg body weight/day. Albumin concentration was 39.4 +/- 5.3 g/L, prealbumin was 0.33 +/- 0.09 g/L, BMI was 23.0 +/- 4.5 kg/m(2). Overall survival was 89.7% +/- 0.8% and 78.4% +/- 1.1% after 1 and 2 years. In the Cox proportional hazard model, survival was significantly influenced by age, the presence of diabetes, and by concentrations of albumin and prealbumin, but not by other variables, including Kt/V and urea reduction ratio. These results indicate that nutritional protein concentrations were predictive of dialysis outcome, whereas variables reflecting actual body composition and dialysis dose were not. Furthermore, in this well-dialyzed population, dialysis adequacy had no influence on survival. In conclusion, when adequacy targets are met in hemodialyzed patients, survival is mainly dependent on age and nutritional status. Efforts should be focused on the most efficient ways to maintain nutritional status in these patients.

Prevalence and consequences of nutritional depletion in lung transplant candidates

Nutritional status was studied in lung transplant (LT) candidates. The hypotheses were that nutritional depletion was highly prevalent and lean body mass depletion was a risk factor for a higher mortality both before and after LT. Of 78 consecutive patients listed for LT, 16 (21%) died while on the waiting list, eight (10%) were alive awaiting LT, and 54 (69%) received a graft. Mean age was 42.3+/-4.4 (mean+/-SD). Thirty-eight per cent had a diagnosis of bronchiectasis or cystic fibrosis (BRO/CF), 33% of emphysema, 20% of idiopathic pulmonary fibrosis (IPF) and 8% of primary pulmonary hypertension. Body mass index (BMI) was 20.4+/-4.3 kg.m2, weight was 87.9+/-16.6% of ideal body weight (IBW). Patients were classed into four nutritional groups according to IBW and creatinine height index (CHI): 1: weight <90% IBW and CHI <60% of predicted (28% of cases); II: weight <90% IBW and CHI > or =60% (27%); III: weight > or =90% IBW and CHI <60% (17%); IV: weight > or =90% IBW and CHI > or =60% (28%). Overall, 72% were depleted corresponding to groups 1, II and III. Lean body mass depletion occurred despite normal weight in 17% of the cases (group III). Subjects with BRO/CF were mostly in groups 1, II, III whereas IPF were concentrated in group II. Lean body mass depletion was associated with more severe hypoxaemia, reduced 6-minute walking distance and a higher mortality while awaiting. After LT, duration of mechanical ventilation, time spent in intensive care unit (ICU) was related to initial body composition. Survival after LT was lowest in group III. To conclude, nutritional depletion in lung transplant candidates is highly prevalent and should be more precisely assessed with a special reference to lean body mass since it has specific consequences both while awaiting and after lung transplant. Attempts should be made to increase lean body mass before lung transplant.

Effects of cardiogenic shock on lactate and glucose metabolism after heart surgery

BACKGROUND

Hyperlactatemia is a prominent feature of cardiogenic shock. It can be attributed to increased tissue production of lactate related to dysoxia and to impaired utilization of lactate caused by liver and tissue underperfusion. The aim of this prospective observational study was to determine the relative importance of these mechanisms during cardiogenic shock.

PATIENTS

Two groups of subjects were compared: seven cardiac surgery patients with postoperative cardiogenic shock and seven healthy volunteers.

METHODS

Lactate metabolism was assessed by using two independent methods: a) a pharmacokinetic approach based on lactate plasma level decay after the infusion of 2.5 mmol x kg(-1) of sodium lactate; and b) an isotope dilution technique for which the transformation of [13C]lactate into [13C]glucose and 13CO2 was measured. Glucose turnover was determined using 6,62H2-glucose.

RESULTS

All patients suffered from profound shock requiring high doses of inotropes and vasopressors. Mean arterial lactate amounted to 7.8 +/- 3.4 mmol x L(-1) and mean pH to 7.25 +/- 0.07. Lactate clearance was not different in the patients and controls (7.8 +/- 3.4 vs. 10.3 +/- 2.1 mL x kg(-1) x min(-1)). By contrast, lactate production was markedly enhanced in the patients (33.6 +/- 16.4 vs. 9.6 +/- 2.2 micromol x kg(-1) x min(-1); p < .01). Exogenous [13C]lactate oxidation was not different (107 +/- 37 vs. 103 +/- 4 mmol), and transformation of [13C]lactate into [13C]glucose was not different (20.0 +/- 13.7 vs. 15.2% +/- 6.0% of exogenous lactate). Endogenous glucose production was markedly increased in the patients (1.95 +/- 0.26 vs. 5.3 +/- 3.0 mg x kg(-1) x min(-1); p < .05 [10.8 +/- 1.4 vs. 29.4 +/- 16.7 micromol x kg(-1) x min(-1)]), whereas net carbohydrate oxidation was not different (1.7 +/- 0.5 vs. 1.3 +/- 0.3 mg x kg(-1) x min(-1) [9.4 +/- 2.8 vs. 7.2 +/- 1.7 micromol x kg(-1) x min(-1)]).

CONCLUSIONS

Hyperlactatemia in early postoperative cardiogenic shock was mainly related to increased tissue lactate production, whereas alterations of lactate utilization played only a minor role. Patients had hyperglycemia and increased nonoxidative glucose disposal, suggesting that glucose-induced stimulation of tissue glucose uptake and glycolysis may contribute significantly to hyperlactatemia.

Three classes of ubiquinone analogs regulate the mitochondrial permeability transition pore through a common site

To identify the structural features required for regulation of the mitochondrial permeability transition pore (PTP) by ubiquinone analogs (Fontaine, E., Ichas, F., and Bernardi, P. (1998) J. Biol. Chem. 40, 25734-25740), we have carried out an analysis with quinone structural variants. We show that three functional classes can be defined: (i) PTP inhibitors (ubiquinone 0, decylubiquinone, ubiquinone 10, 2,3-dimethyl-6-decyl-1,4-benzoquinone, and 2,3,5-trimethyl-6-geranyl-1,4-benzoquinone); (ii) PTP inducers (2,3-dimethoxy-5-methyl-6-(10-hydroxydecyl)-1,4-benzoquinone and 2,5-dihydroxy-6-undecyl-1,4-benzoquinone); and (iii) PTP-inactive quinones that counteract the effects of both inhibitors and inducers (ubiquinone 5 and 2,3,5-trimethyl-6-(3-hydroxyisoamyl)-1,4-benzoquinone) . The structure-function correlation indicates that minor modifications in the isoprenoid side chain can turn an inhibitor into an activator, and that the methoxy groups are not essential for the effects of quinones on the PTP. Since the ubiquinone analogs used in this study have a similar midpoint potential and decrease mitochondrial production of reactive oxygen species to the same extent, these results support the hypothesis that quinones modulate the PTP through a common binding site rather than through oxidation-reduction reactions. Occupancy of this site can modulate the PTP open-closed transitions, possibly through secondary changes of the PTP Ca(2+) binding affinity.

Acidosis and nutritional status in hemodialyzed patients. French Study Group for Nutrition in Dialysis

In a cross-sectional study of more than 30% of French dialysis patients (N = 7,123), we evaluated the relationships between predialysis plasma bicarbonate concentration and nutritional markers. Data including age, gender, cause of end-stage renal disease (ESRD), time on dialysis, body mass index (BMI), blood levels of midweek predialysis albumin, prealbumin, and bicarbonate were collected. Normalized protein catabolic rate (nPCR), dialysis adequacy parameters, and estimation of lean body mass (LBM) were computed from pre- and postbicarbonate-dialysis urea and creatinine levels according to the classical formulas of Garred. Average values (+/- 1 SD) were age 61 +/- 16 years, BMI 23.3 +/- 4.6 kg/m2, dialysis time 12.4 +/- 2.7 h/week, HCO3 22.8 +/- 3.5 mmol/L, albumin 38.7 +/- 5.3 g/L, prealbumin 340 +/- 90 mg/L, Kt/V 1.36 +/- 0.36, nPCR 1.13 +/- 0.32 g/kg BW/day, and LBM 0.86 +/- 0.21% of ideal LBM. A highly significant negative correlation was observed between predialysis bicarbonate levels (within a range of 16-30 mmol/L, 95% of this population) and nPCR confirmed by analysis of variance using bicarbonate classes (p < 0.0001). Bicarbonate was also negatively correlated with albumin, prealbumin, BMI, and LBM. No relationship was noted between bicarbonate and Kt/V despite a positive correlation between Kt/V and nPCR. It is likely that a persistent acidosis observed despite standard bicarbonate dialysis was caused by a high dietary protein intake which results in an increased acid load, but also overcomes the usual catabolic effects of acidosis.

Dimethylbiguanide inhibits cell respiration via an indirect effect targeted on the respiratory chain complex I

We report here a new mitochondrial regulation occurring only in intact cells. We have investigated the effects of dimethylbiguanide on isolated rat hepatocytes, permeabilized hepatocytes, and isolated liver mitochondria. Addition of dimethylbiguanide decreased oxygen consumption and mitochondrial membrane potential only in intact cells but not in permeabilized hepatocytes or isolated mitochondria. Permeabilized hepatocytes after dimethylbiguanide exposure and mitochondria isolated from dimethylbiguanide pretreated livers or animals were characterized by a significant inhibition of oxygen consumption with complex I substrates (glutamate and malate) but not with complex II (succinate) or complex IV (N,N,N',N'-tetramethyl-1, 4-phenylenediamine dihydrochloride (TMPD)/ascorbate) substrates. Studies using functionally isolated complex I obtained from mitochondria isolated from dimethylbiguanide-pretreated livers or rats further confirmed that dimethylbiguanide action was located on the respiratory chain complex I. The dimethylbiguanide effect was temperature-dependent, oxygen consumption decreasing by 50, 20, and 0% at 37, 25, and 15 degrees C, respectively. This effect was not affected by insulin-signaling pathway inhibitors, nitric oxide precursor or inhibitors, oxygen radical scavengers, ceramide synthesis inhibitors, or chelation of intra- or extracellular Ca(2+). Because it is established that dimethylbiguanide is not metabolized, these results suggest the existence of a new cell-signaling pathway targeted to the respiratory chain complex I with a persistent effect after cessation of the signaling process.

Mechanisms of increased gluconeogenesis from alanine in rat isolated hepatocytes after endurance training

This work aimed at further investigating the mechanisms by which liver gluconeogenic capacity from alanine is improved after training in rats, with an isolated hepatocyte model. Compared with controls in hepatocytes from trained rats incubated with gluconeogenic precursors (20 mM), the glucogenic flux (J(glucose)) was increased by 64% from alanine (vs. 21% for glycerol, 18% for lactate-pyruvate 10:1, and 10% for dihydroxyacetone). Maximal intracellular alanine accumulation capacity was also increased by 50%. Further experiments conducted on perifused hepatocytes showed that the putative adaptation at the level of the phosphoenolpyruvate-pyruvate cycle, which could be involved in the increased J(glucose) from lactate-pyruvate, was not involved in the increased J(glucose) from alanine after training. For alanine concentration higher than approximately 1 mM, an increased flux through alanine aminotransferase appeared responsible for the increased J(glucose). This could, in turn, depend on an increased supply of cytosolic 2-oxoglutarate because of the higher mitochondrial respiration observed in hepatocytes from trained rats and the activation of the malate-aspartate shuttle. At lower alanine concentration, the increase in J(glucose) appeared to be entirely due to the improved transport capacity.

Nutritional status of haemodialysis patients: a French national cooperative study. French Study Group for Nutrition in Dialysis

BACKGROUND

Despite the severity and the prognosis value of undernutrition in haemodialysed patients, no large study is available as yet in Europe. Hence, this French National Cooperative Study aimed to determine the prevalence of undernutrition and its relationship to dialysis efficacy.

METHODS

Nutritional status was determined in 7123 patients (i.e. one-third of the French haemodialysis population) using body mass index (BMI), predialysis haemoglobin, albumin, pre-albumin, cholesterol, and also normalized protein catabolic rate (nPCR) and lean body mass (LBM) calculated from pre- and postdialysis urea and creatinine. Dialysis treatment was estimated from weekly dialysis time and KtV determination.

RESULTS

Dialysis time was 12.4+/-2.7 h/week and KtV 1.36+/-0.36. BMI was below 20 kg/m2 in 24% and the observed/expected LBM ratio below 90% in 62%. Albumin, pre-albumin and nPCR were below the high-risk thresholds of 35 g/l, 300 mg/l and 1g/kg/day in 20%, 36% and 35% of patients, respectively. Pre-albumin was the most representative nutritional parameter. Albumin, pre-albumin and LBM correlated with nPCR. A dialysis time above 12 h/week was associated with higher BMI, albumin, pre-albumin and LBM. LBM was higher in patients with a KtV value >1.1.

CONCLUSION

This study showed life-threatening undernutrition in 20-36% of the studied population, according to nutritional parameters. Protein intake (estimated by nPCR) and dialysis efficacy (estimated by dialysis time and KtV) appeared to be major determinants of nutritional status in this population.

A generic model for Internet-accessed databases in epidemiology: a nutritional application

The Web technology has made the exchange of information among heterogeneous platforms possible with no added cost to end-users. Adding to this, it made it possible to access databases residing on servers in different geographic locations giving thus conceptors and programmers the possibility of making distributed applications with a fraction of the time needed before. This technology is therefore very well suited to medical applications which are normally multi-user, multiplatform, and data-intensive. In this paper, we present an application for epidemiological studies based on the Web technology and the reuse of common concepts in epidemiology to produce a generic model that can be parameterisable by the end-user to suit the needs of his study. This model is then applied to develop an application to optimise the collection and processing of nutritional data for a nation-wide epidemiological study concerning renal failure patients.

Effect of major hepatectomy on glucose and lactate metabolism

BACKGROUND

The liver plays an important role in glucose and lactate metabolism. Major hepatectomy may therefore be suspected to cause alterations of glucose and lactate homeostasis.

METHODS

Thirteen subjects were studied: six patients after major hepatectomy and seven healthy subjects who had fasted overnight. Glucose turnover was measured with 6,6(2)H glucose. Lactate metabolism was assessed using two complementary approaches: 13C-glucose synthesis and 13CO2 production from an exogenous 13C-labeled lactate load infused over 15 minutes were measured, then the plasma lactate concentrations observed over 185 minutes after lactate load were fitted using a biexponential model to calculate lactate clearance, endogenous production, and half-lives.

RESULTS

Three to five liver segments were excised. Compared to healthy controls, the following results were observed in the patients: 1) normal endogenous glucose production; 2) unchanged 13C-lactate oxidation and transformation into glucose; 3) similar basal plasma lactate concentration, lactate clearance, and lactate endogenous production; 4) decreased plasma lactate half-life 1 and increased half-life 2.

CONCLUSIONS

Glucose and lactate metabolism are well maintained in patients after major hepatectomy, demonstrating a large liver functional reserve. Reduction in the size of normal liver parenchyma does not lead to hyperlactatemia. The use of a pharmacokinetic model, however, allows the detection of subtle alterations of lactate metabolism.

Enteral nutrition in intensive care patients: a practical approach

Severe protein-calorie malnutrition is a major problem in many intensive care (ICU) patients, due to the increased catabolic state often associated with acute severe illness and the frequent presence of prior chronic wasting conditions. Nutritional support is thus an important part of these patient's management. Over the years, enteral nutrition (EN) has gained considerable popularity, due to its favorable effects on the digestive tract and its lower cost and rate of complications compared to parenteral nutrition. However, clinicians caring for ICU patients are often faced with contradictory data and difficult decision-making when having to determine the optimal timing and modalities of EN administration, estimation of patient requirements and choice of formulas. The purpose of this paper is to provide practical guidelines on these various aspects of enteral nutritional support, based on presently available evidence.

[Cellular energy metabolism: physiologic and pathologic aspects]

Cellular homeostasis requires permanent energy production and consumption. Adenosine triphosphate (ATP) is the major energy component for the cell. Its synthesis occurs mainly in mitochondria where the oxidative phosphorylations realise the coupling between oxygen consumption and phosphorylation of adenosine diphosphate. The anaerobic production of ATP plays an important role in the intermediary metabolism. The enzymatic complexes of the mitochondrial respiratory chain are energy transducers acting as proton pumps. In cardiomyocytes, the phosphocreatine circuit allows a substrate channelling between mitochondria and myofibrils. This metabolic compartmentation explains the difficulties of studying energetic metabolism in the beating heart and the lack of correlation between cardiac function and the usual energy parameters. Mitochondria are a potential site of action of anaesthetic agents. Lipophilic local anaesthetics impair cellular energy metabolism and mitochondrial ATP production. Such effects could be associated with toxic effects of these molecules. NMR or near-infrared spectroscopy are non invasive techniques for monitoring energetic metabolism in vivo. Clinical applications are developed for analysing brain, muscle or cardiac function in physiological and pathological conditions.

Cellular physiology and molecular events in hypoxia-induced apoptosis

Malignant tumors contain a significant fraction of microregions that are chronically or transiently hypoxic. The experimental evidence showing that hypoxia may have a profound impact on malignant progression and on responsiveness to therapy is growing. In fact hypoxia, like other genotoxic and non-genotoxic stresses, has been shown to increase the p53 protein level, and subsequently activate target genes like p21/waf-1 which interact with cell cycle machinery or participate in apoptosis. Apoptosis is a genetically encoded program of cell death that can be activated under physiological conditions like hypoxia, and may be an important safeguard against tumour development. One of the first common manifestations of the apoptotic process, irrespective of the cell type, is the disruption of mitochondrial membrane function, including a dissipation of the delta psi m and/or a modification on the mitochondrial release of protease activators. These modifications are linked to specific patterns of bioenergetic parameters i.e. respiratory flux, mitochondrial redox potential and phosphate potential. We have studied gluconeogenesis and glycolysis pathways in intact hepatocytes isolated from fasted rats submitted to 24 h of hypoxic in vivo exposure. We have shown that hypoxia resulted in an inhibition of the gluconeogenesis pathway due to a decrease in phosphoenolpyruvate carboxykinase (PEPCK) activity and mRNA synthesis in rat hepatocytes. In conclusion, the disruption of mitochondrial membrane function in response to different oxygen content such as periarterial or perivenous PO2 led to the inhibition of gluconeogenesis and apoptosis in hypoxic cells.

Hypocapnia does not alter hepatic blood flow or oxygen consumption in patients with head injury

OBJECTIVE

To evaluate the effects of hypocapnia on the systemic and hepatic circulations and oxygenation values in patients with head injury.

DESIGN

Open-label, prospective study.

SETTING

University hospital, department of anesthesiology and intensive care unit.

PATIENTS

Eleven mechanically ventilated patients with isolated head trauma and stable hemodynamic status.

INTERVENTIONS

At the beginning of the study, each patient presented with normocapnic ventilation. Mechanical hyperventilation was then adjusted to obtain stable hypocapnia over an interval of 24 hrs. Cardiac output and other systemic hemodynamic parameters were measured, using a pulmonary artery catheter. Hepatic parameters were measured via a catheter inserted into the hepatic vein. Total hepatic blood flow was determined by the Fick principle using a continuous infusion of indocyanine green. Arterial and hepatic venous blood gases were sampled to determine systemic and hepatic-splanchnic oxygenation. Measurements were done at the end of the four phases: a) 30 mins of normocapnia (N); b) 30 mins of hypocapnia (H0); c) 3 hrs of hypocapnia (H3); and d) 24 hrs of hypocapnia (H24). Intracranial pressure and cerebral perfusion pressure were hourly monitored throughout the study.

MEASUREMENTS AND MAIN RESULTS

There were no significant changes in systemic hemodynamic parameters. The hepatic blood flow index did not differ from normocapnia (N 1.8 +/- 0.4 L/min/m2) to hypocapnia (H0 1.6 +/- 0.3 L/min/m2; H3 1.7 +/- 0.4 L/min/m2; H24 1.7 +/- 0.4 L/min/m2). The ratio of hepatic blood flow index to cardiac index remained stable throughout the study. Hypocapnia did not affect hepatic-splanchnic oxygen delivery and consumption.

CONCLUSIONS

Hypocapnic hyperventilation does not alter hepatic hemodynamic parameters in patients with head injury. This result may be related to the lack of changes in cardiac output or in the hepatic vasoreactivity. Moreover, hypocapnia does not modify hepatic-splanchnic oxygenation. Thus, in case of intracranial hypertension, hypocapnia might be used without undesirable effect on the hepatic-splanchnic perfusion.

Enteral nutrition in intensive care patients: a practical approach. Working Group on Nutrition and Metabolism, ESICM. European Society of Intensive Care Medicine

Severe protein-calorie malnutrition is a major problem in many intensive care (ICU) patients, due to the increased catabolic state often associated with acute severe illness and the frequent presence of prior chronic wasting conditions. Nutritional support is thus an important part of the management of these patients. Over the years, enteral nutrition (EN) has gained considerable popularity, due to its favorable effects on the digestive tract and its lower cost and rate of complications compared to parenteral nutrition. However, clinicians caring for ICU patients are often faced with contradictory data and difficult decisions when having to determine the optimal timing and modalities of EN administration, estimation of patient requirements, and choice of formulas. The purpose of this paper is to provide practical guidelines on these various aspects of enteral nutritional support, based on presently available evidence.

Oxidative phosphorylation in intact hepatocytes: quantitative characterization of the mechanisms of change in efficiency and cellular consequences

Two mechanisms may affect the yield of the oxidative phosphorylation pathway in isolated mitochondria: (i) a decrease in the intrinsic coupling of the proton pumps (H+/2e- or H+/ATP), and (ii) an increase in the inner membrane conductance (proton or cation leak). Hence three kinds of modifications can occur and each of them have been characterized in isolated rat liver mitochondria (see preceding chapter by Rigoulet et al.). In intact isolated hepatocytes, these modifications are linked to specific patterns of bioenergetic parameters, i.e. respiratory flux, mitochondrial redox potential, DY, and phosphate potential. (1) The increase in H+/ATP stoichiometry of the mitochondrial ATP synthase, as induced by almitrine [20], leads to a decrease in mitochondrial and cytosolic ATP/ADP ratios without any change in the protonmotive force nor in the respiratory rate or redox potential. (2) In comparison to carbohydrate, octanoate metabolism by beta-oxidation increases the proportion of electrons supplied at the second coupling site of the respiratory chain. This mimics a redox slipping. Octanoate addition results in an increased respiratory rate and mitochondrial NADH/NAD ratio while protonmotive force and phosphate potential are almost unaffected. The respiratory rate increase is associated with a decrease in the overall apparent thermodynamic driving force (2deltaE'o - ndeltap) which confirms the 'redox-slipping-like' effect. (3) An increase in proton conductance as induced by the protonophoric uncoupler 2,4-dinitrophenol (DNP) leads to a decrease, as expected, in the mitochondrial NADH/NAD and ATP/ ADP ratios and in deltapsi while respiratory rate is increased. Thus, each kind of modification (proton leak, respiratory chain redox slipping or increase in H+/ATP stoichiometry of ATPase) is related to a specific set of bioenergetic parameters in intact cells. Moreover, these patterns are in good agreement with the data found in isolated mitochondria. From this work, we conclude that quantitative analysis of four bioenergetic parameters (respiration rate, mitochondrial NADH/ NAD ratio, protonmotive force and mitochondrial phosphate potential) gives adequate tools to investigate the mechanism by which some alterations may affect the yield of the oxidative phosphorylation pathway in intact cells.

Quantitative analysis of some mechanisms affecting the yield of oxidative phosphorylation: dependence upon both fluxes and forces

The purpose of this work was to show how the quantitative definition of the different parameters involved in mitochondrial oxidative phosphorylation makes it possible to characterize the mechanisms by which the yield of ATP synthesis is affected. Three different factors have to be considered: (i) the size of the different forces involved (free energy of redox reactions and ATP synthesis, proton electrochemical difference); (ii) the physical properties of the inner mitochondrial membrane in terms of leaks (H+ and cations); and finally (iii) the properties of the different proton pumps involved in this system (kinetic properties, regulation, modification of intrinsic stoichiometry). The data presented different situations where one or more of these parameters are affected, leading to a different yield of oxidative phosphorylation. (1) By manipulating the actual flux through each of the respiratory chain units at constant protonmotive force in yeast mitochondria, we show that the ATP/O ratio decreases when the flux increases. Moreover, the highest efficiency was obtained when the respiratory rate was low and almost entirely controlled by the electron supply. (2) By using almitrine in different kinds of mitochondria, we show that this drug leads to a decrease in ATP synthesis efficiency by increasing the H+/ATP stoichiometry ofATP synthase (Rigoulet M et al. Biochim Biophys Acta 1018: 91-97, 1990). Since this enzyme is reversible, it was possible to test the effect of this drug on the reverse reaction of the enzyme i.e. extrusion of protons catalyzed by ATP hydrolysis. Hence, we are able to prove that, in this case, the decrease in efficiency of oxidative phosphorylation is due to a change in the mechanistic stoichiometry of this proton pump. To our knowledge, this is the first example of a modification in oxidative phosphorylation yield by a change in mechanistic stoichiometry of one of the proton pumps involved. (3) In a model of polyunsaturated fatty acid deficiency in rat, it was found that non-ohmic proton leak was increased, while ohmic leak was unchanged. Moreover, an increase in redox slipping was also involved, leading to a complex picture. However, the respective role of these two mechanisms may be deduced from their intrinsic properties. For each steady state condition, the quantitative effect of these two mechanisms in the decrease of oxidative phosphorylation efficiency depends on the values of different fluxes or forces involved. (4) Finally the comparison of the thermokinetic data in view of the three dimensional-structure of some pumps (X-ray diffraction) also gives some information concerning the putative mechanism of coupling (i.e. redox loop or proton pump) and their kinetic control versus regulation of mitochondrial oxidative phosphorylation.

Flux-force relationships in intact cells: a helpful tool for understanding the mechanism of oxidative phosphorylation alterations?

On isolated mitochondria, numerous studies of the relationships between fluxes and their associated forces have led to the description of some properties of the oxidative phosphorylation pathway. However whether such an approach can be applied to understanding the actual situation in intact living cells needs further consideration. In this study on isolated hepatocytes, we describe the dependence of the respiratory rate on the three thermodynamic forces linked to oxidative phosphorylation (i.e. the redox span over the respiratory chain, the electrical potential difference across the inner mitochondrial membrane and the free energy of ATP synthesis reaction). Even if this description is phenomenological and some objections may be raised regarding the relevance of such a bulk-phase force estimation, we present some results showing that the study of flux-force relationships in intact cells may be a helpful approach for understanding the mechanisms by which oxidative phosphorylation activity is changed.

2,4 Dinitrophenol-uncoupling effect on delta psi in living hepatocytes depends on reducing-equivalent supply

Mitochondrial uncouplers, such as 2,4 dinitrophenol (DNP), increase the cellular respiration by decreasing mitochondrial membrane potential (delta psi). We show that this respiratory effect can be transient or even prevented in isolated liver cells depending on the exogenous substrate used (dihydroxyacetone vs. octanoate or proline). Moreover the decrease in ATP/ADP ratio induced by DNP is partially restored by addition of octanoate or proline. By using rhodamine 123 (Rh123) monitored by flow cytometry in living hepatocytes, we were able to follow in time delta psi in such DNP-uncoupled cells incubated with various substrates. The ability of this method to evaluate delta psi changes was assessed by using myxothiazol (3.6 microM), an inhibitor of the b-c1 complex of the respiratory chain which decreased delta psi (65%), or oligomycin (6 microg/ml), an inhibitor of the F0F1-ATPase which increased it (50%). Although DNP induced a dose-dependent decrease of delta psi, we found that octanoate or proline addition prevented such effect. We propose that octanoate or proline may counteract the uncoupling effect of DNP by providing a high supply of reducing equivalents to the respiratory chain.

[A 1993-1995 epidemiological survey of home parenteral nutrition in approved centers for adults in France]

OBJECTIVES

A 1993-1995 three year epidemiological survey of home parenteral nutrition was performed through in France in approved centers for adults.

METHODS

Data were retrospectively collected each year on a standardized questionnaire focussing on indications and short term outcome.

RESULTS

All centers (n = 14) participated in the study and 524 new adult patients were recruited. The overall incidence was unchanged at 3.75 patients/10(6) adults. Indications for AIDS rose (8 to 18%) whereas other indications were stable. Prevalence increased by 19%: 4.40 adults/10(6) patients at 01.01.1996. At six months, the probability to stay on treatment was 19.5% for AIDS and cancer indications but 52% for others, whereas death rates were 59% and 9% respectively.

CONCLUSIONS

For both cancer and AIDS indications, short-term treatment was due to a poor prognosis. For other diagnosis, complicated with a short bowel in 51% of cases, prognosis was excellent but associated with treatment dependency. The latter point focuses on the need for additional treatments in irreversible intestinal failure.

Effect of parenteral medium- and long-chain triglycerides on lymphocytes subpopulations and functions in patients with acquired immunodeficiency syndrome: a prospective study

BACKGROUND

Total parenteral nutrition (TPN) may offer significant clinical benefit in malnourished patients with acquired immunodeficiency syndrome (AIDS). However, the immunologic effect of parenteral lipids remains unknown in these severely immunodepressed patients.

METHODS

We undertook a prospective randomized double-blind multicenter study comparing the effects of two i.v. lipid emulsions used during TPN: long-chain triglycerides (LCT) or balanced emulsion of long-and medium-chain triglycerides (LCT/MCT). Thirty-three AIDS patients requiring TPN for wasting and reduced oral intake were allocated randomly to receive a ternary TPN mixture consisting of 1.5 g/kg/d proteins, 18 kcal/kg/d lipids, and 12 Kcal/kg/d carbohydrates for 6 days. The following tests were performed at days 0 and 7: immunoglobulins, complement fractions, lymphocyte subpopulations count, and lymphocyte proliferation with mitogens.

RESULTS

Patients were all severely malnourished (weight loss: -14.0 +/- 1.3 kg). No clinical or biological differences were observed between the groups at baseline. At day 7, both groups reported a significant increase in weight. Patients in the LCT group exhibited a significant decrease in phytohemagglutinin A response (p = .04) compared with baseline. Patients in the LCT/MCT group exhibited a lower level of IgM (p = .03) and significant increase in C3 fraction (p = .03) compared with baseline. They also showed a tendency to have a higher CD4/CD8 lymphocyte ratio (p = .07), whereas other immunological parameters remained unchanged

CONCLUSIONS

Parenteral ternary mixture containing LCT or LCT/MCT are clinically well tolerated in AIDS patients over 6 days. With 2 g/kg/d of lipids, LCT seems to induce significant abnormalities in lymphocyte function. Such abnormalities are not observed with LCT/MCT.

Study of regulation of mitochondrial respiration in vivo. An analysis of influence of ADP diffusion and possible role of cytoskeleton

The purpose of this work was to investigate the mechanism of regulation of mitochondrial respiration in vivo in different muscles of normal rat and mice, and in transgenic mice deficient in desmin. Skinned fiber technique was used to study the mitochondrial respiration in the cells in vivo in the heart, soleus and white gastrocnemius skeletal muscles of these animals. Also, cardiomyocytes were isolated from the normal rat heart, permeabilized by saponin and the "ghost" (phantom) cardiomyocytes were produced by extraction of myosin with 800 mM KCl. Use of confocal immunofluorescent microscopy and anti-desmin antibodies showed good preservation of mitochondria and cytoskeletal system in these phantom cells. Kinetics of respiration regulation by ADP was also studied in these cells in detail before and after binding of anti-desmine antibodies with intermediate filaments. In skinned cardiac or soleus skeletal muscle fibers but not in fibers from fast twitch skeletal muscle the kinetics of mitochondrial respiration regulation by ADP was characterized by very high apparent Km (low affinity) equal to 300-400 microM, exceeding that for isolated mitochondria by factor of 25. In skinned fibers from m. soleus, partial inhibition of respiration by NaN3 did not decrease the apparent Km for ADP significantly, this excluding the possible explanation of low apparent affinity of mitochondria to ADP in these cells by its rapid consumption due to high oxidative activity and by intracellular diffusion problems. However, short treatment of fibers with trypsin decreased this constant value to 40-70 microM, confirming the earlier proposition that mitochondrial sensitivity to ADP in vivo is controlled by some cytoplasmic protein. Phantom cardiomyocytes which contain mostly mitochondria and cytoskeleton and retain the normal shape, showed also high apparent Km values for ADP. Therefore, they are probably the most suitable system for studies of cellular factors which control mitochondrial function in the cells in vivo. In these phantom cells anti-desmin antibodies did not change the kinetics of respiration regulation by ADP. However, in skinned fibers from the heart and m. soleus of transgenic desmin-deficient mice some changes in kinetics of respiration regulation by ADP were observed: in these fibers two populations of mitochondria were observed, one with usually high apparent Km for ADP and the second one with very low apparent Km for ADP. Morphological observations by electron microscopy confirmed the existence of two distinct cellular populations in the muscle cells of desmin-deficient mice. The results conform to the conclusion that the reason for observed high apparent Km for ADP in regulation of oxidative phosphorylation in heart and slow twitch skeletal muscle cells in vivo is low permeability of mitochondrial outer membrane porins but not diffusion problems of ADP into and inside the cells. Most probably, in these cells there is a protein associated with cytoskeleton, which controls the permeability of the outer mitochondrial porin pores (VDAC) for ADP. Desmin itself does not display this type of control of mitochondrial porin pores, but its absence results in appearance of cells with disorganised structure and of altered mitochondrial population probably lacking this unknown VDAC controlling protein. Thus, there may be functional connection between mitochondria, cellular structural organisation and cytoskeleton in the cells in vivo due to the existence of still unidentified protein factor(s).

Comparison of subcutaneous and intravenous administration of a solution of amino acids in older patients

OBJECTIVE

To compare the plasma amino acid (AA) concentrations obtained by the infusion of an AA solution (660 mOsm/L, pH 7) using the subcutaneous (SC) with that using the intravenous (i.v.) route in older patients.

DESIGN

A prospective, randomized, cross-over study.

SETTING

A hospital geriatric ward.

PARTICIPANTS

Six patients with a mean age of 84 years.

MEASUREMENTS

The infusion of the AA solution (IV or SC) lasted 6 hours. Blood was sampled at 0, 2, 4, 6, 8, 10, 14, 18, and 24 hours from the start of the infusion to determine plasma AA level by the phenyl-isothiocyanate method.

RESULTS

Compared with baseline values, plasma AA concentrations increased to a significantly higher level from the second to the tenth hour and from the second to the fourteenth hour during i.v. and SC infusions, respectively. Plasma AA levels did not differ between the two routes. SC infusion was well tolerated.

CONCLUSION

Assuming that nutritional sufficiency is the desired result of plasma AA infusion, we conclude the SC route is well tolerated and offers the possibility of nitrogen supplementation for older patients over short periods of time, when oral protein intake is transiently insufficient or impossible, as a way to limit, but not to treat, protein-energy malnutrition.

Action potentials in right and left ventricles from chronic hypoxic rats: effect of almitrine

Rats were exposed to a 3-wk regimen of chronic normobaric hypoxia, with or without almitrine treatment. Chronic hypoxia led to a significant rise in the right ventricular mass and lengthened the action potential duration (APD) in right ventricle and in nonhypertrophied left ventricle. Hypertrophy and APD lengthening were significantly enhanced by almitrine. The classical acute hypoxia-induced shortening in APD was much larger in hypoxia-adapted hearts. In these hearts, almitrine treatment almost completely prevented such shortening, while the acute hypoxia-induced decrease in cardiac contraction was similar with or without almitrine. It is concluded that APD lengthening during chronic hypoxia can occur independently of ventricular hypertrophy. The similar directional effects of almitrine and chronic hypoxia on APD support the hypothesis of an energy-linked phenomenon. The dissociation of the almitrine effect on APD and contractility is in accordance with the view of a cellular energy compartmentation.