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PubMed1998

Small cell lung cancer accompanied by lactic acidosis and syndrome of inappropriate secretion of antidiuretic hormone.

Lactic acidosis is a rare complication in lung cancer. We report a case of lung cancer accompanied by both syndrome of inappropriate secretion of antidiuretic hormone (SIADH) and lactic acidosis. A 70-year-old man was referred to our hospital for examination of a left hilar mass shadow on a chest X-ray film. Small cell lung cancer (SCLC) was demonstrated by brushing the bronchial mucosa of the left lower lobe bronchus. His laboratory data showed SIADH and lactic acidosis that were probably due to SCLC. Fluid restriction improved SIADH, and combination chemotherapy for SCLC improved the lactic acidosis although the tumor size did not change.

Acidosis, Lactic↗
PubMedDate not supplied

Metabolic acidosis and hepatic steatosis in two HIV-infected patients on stavudine (d4T) treatment.

Nucleoside analog reverse transcriptase inhibitors (NRTI) have been used to treat HIV-infected patients for >10 years. Some severe adverse events have been attributed to mitochondrial dysfunction. Since 1991, cases of severe lactic acidosis have been reported in association with nucleoside therapy. Our objective was to report two cases of metabolic acidosis and hepatic steatosis in patients receiving stavudine (d4T) and to review the literature. A male and a female, 47 and 45 years of age, respectively, presented with abdominal pain, nausea, vomiting, and weakness after 9 and 6 months, respectively, of treatment with stavudine. At presentation, both patients had severe metabolic acidosis and liver failure. Ultrasonography showed hepatic steatosis (confirmed by biopsy in one case). All antiretroviral drugs were withdrawn and patients were treated with bicarbonate. Both patients developed fulminant liver dysfunction and multiple organ failure. We reviewed the literature and found 75 cases of lactic acidosis and hepatic steatosis associated with use of NRTI; 57 of these patients received d4T (76%). Of all cases reported in association with nucleoside therapy, 63% were females and mortality was 47%. General weakness, hepatic enzyme elevation, and liver steatosis are data that should alert physicians to this serious adverse event and to respond with prompt interruption of antiretroviral drugs and measurement of lactic acid in plasma. It is important to report serious adverse events in commercially released drugs to know prevalence in an exposed population. Physicians should be aware of risk and early signs of this serious adverse event.

Acidosis, Lactic↗
PubMed1985

Brain acidosis.

Brain tissue acidosis is a result of either an increase in tissue PCO2 or an accumulation of acids produced by metabolism. Severe hypercapnia (arterial PCO2 around 300 mm Hg) may cause a fall in tissue pH to around 6.6 without any deterioration of the cerebral energy state or morphologic evidence of irreversible cell damage. In severe ischemia and tissue hypoxia, anaerobic glycolysis leads to lactic acid accumulation. This is aggravated by hyperglycemia and by a (trickling) residual blood flow. Under such circumstances lactate concentration in the tissue may increase to levels above 20 to 25 mumol/g (tissue wet weight), causing a decrease in pH to around 6.0. If lactic acidosis during ischemia or hypoxia reaches these excessive levels, metabolic and functional restitution is severely hampered upon subsequent recirculation and reoxygenation. In these circumstances cell morphology shows signs of irreversible damage. Conversely there is less damage if severe tissue lactic acidosis can be hindered. The deleterious effect of excessive lactic acidosis may be related to an influence on the following: synthesis and degradation of cellular constituents; mitochondrial function; cell volume control; postischemic blood flow; and stimulation of pathologic free radical reactions. Possibilities for therapeutic interventions include the avoidance of hyperglycemia, inhibition of glycolysis, and measures for increasing the buffer capacity of the brain.

Acidosis↗
PubMed2000

Acidosis and astrocyte amino acid metabolism.

The relationship between acidosis and the metabolism of glutamine and glutamate was studied in cultured astrocytes. Acidification of the incubation medium was associated with an increased formation of aspartate from glutamate and glutamine. The rise of the intracellular content of aspartate was accompanied by a significant decline in the extracellular concentration of both lactate and citrate. Studies with either [2-(15)N]glutamine or [15N]glutamate indicated that there occurred in acidosis an increased transamination of glutamate to aspartate. Studies with L-[2,3,3,4,4-(2)H5]glutamine indicated that in acidosis glutamate carbon was more rapidly converted to aspartate via the tricarboxylic acid cycle. Acidosis appears to result in increased availability of oxaloacetate to the aspartate aminotransferase reaction and, consequently, increased transamination of glutamate. The expansion of the available pool of oxaloacetate probably reflects a combination of: (a) Restricted flux through glycolysis and less production from pyruvate of acetyl-CoA, which condenses with oxaloacetate in the citrate synthetase reaction; and (b) Increased oxidation of glutamate and glutamine through a portion of the tricarboxylic acid cycle and enhanced production of oxaloacetate from glutamate and glutamine carbon. The data point to the interplay of the metabolism of glucose and that of glutamate in these cells.

Acidosis↗
PubMed2003

[Severe lactic acidosis in HIV-infected patients treated with nucleosidic reverse transcriptase analogs: a report of 9 cases].

PURPOSE: Symptomatic lactic acidosis requiring intensive care is a rare and severe adverse event related to the mitochondrial toxicity of the nucleoside analog reverse transcriptase inhibitors (NRTIs). METHOD: We retrospectively investigated the clinical and biological features of HIV-infected patients who developed severe lactic acidosis syndrome at the University teaching hospital of Bordeaux and the regional community hospital, during 1996-2000. RESULTS: Nine patients were identified (incidence: 0,9/1000 NRTI treated patient-years), 4 men and 5 women with a median age of 36 years. They had a moderate immunodeficiency (median CD4+ T lymphocyte counts: 197/mm(3)) and only one of them presented a virological failure. The causes of hospital admission were abdominal pain (n = 6), dyspnea (n = 6), asthenia (n = 5), jaundice (n = 4), and vomiting (n = 2). Hepatomegaly was present in 6 patients. Lactic acidosis was found in all cases: median pH: 7.28, bicarbonate: 12 mmol/l, anion gap: 27 mEq/l, plasma lactic acid: 13 mmol/l. Cytolysis (n = 8), cholestasis (n = 6), hepatic failure (n = 4), rhabdomyolysis (n = 4) and pancreatitis (n = 2), were also present. Despite medical intensive care, seven patients died. The only two post-mortem examinations revealed severe hepatic steatosis. Median duration of NRTI therapy was 4 years. At presentation, five patients were receiving lamivudine, five didanosine, four stavudine and three zidovudine. Six patients were coinfected by HCV and/or HBV, four had chronic renal failure and five an immediately preceding infectious disease. CONCLUSION: The prognosis of lactic acidosis is severe. Nucleosid-analog therapy needs clinical and biological monitoring, specially in patients with comorbidities.

Abdominal Pain↗
PubMed1992

Might distal renal tubular acidosis be a proximal tubular cell disorder?

Incomplete renal tubular acidosis (RTA) and overt distal RTA may be different stages of the same underlying pathophysiology in certain individuals. The rationale that draws these conditions together is the relatively alkaline pH of the urine, hypocitraturia, and a possible familial association. The rate of excretion of ammonium (NH4+), on the other hand, suggests that these conditions stem from fundamentally different lesions. To explain this difference, we suggest that two possible disorders may result in the evolution from incomplete RTA to overt distal RTA. One subgroup could have gradient-limited distal RTA, while the other subgroup may have a lower pH of the intracellular fluid of the proximal convoluted tubular epithelium. Indices of proximal intracellular pH (rates of excretion of NH4+, NH3, and citrate) were culled from the literature spanning the years 1959 to 1991 on patients with incomplete RTA and overt distal RTA. Three points emerge: (1) the rate of excretion of NH4+ was lower in patients with overt distal RTA than in normals following an acute acid load (23 +/- 1 v 49 +/- 3 mumol/min); (2) the concentration of NH3 in the urine was almost 25-fold higher in incomplete RTA than in normals (69 +/- 14 v 3 +/- 0.4 nmol/min); and (3) in incomplete RTA, the pH of the urine fell to very low values (4.9 +/- 0.1) when high urine flows were induced with furosemide. The low pH of the urine would therefore suggest that many of these patients do not gradient-limited distal RTA, but more likely have proximal renal epithelial cell acidosis. We hypothesize that this high rate of excretion of NH4+ and low rate of excretion of citrate in the absence of acidosis or hypokalemia is consistent with proximal cell acidosis. To explain a transition from incomplete RTA to overt distal RTA, we speculate that toxicity of high concentrations of NH3 in the medullary interstitium as well as nephrolithiasis and nephrocalcinosis due to low urinary citrate and possibly an alkaline medullary interstitium may lead to damage of structures in this region.

Acid-Base Equilibrium↗
PubMed1985

An unsuspected cause for metabolic acidosis in chronic renal failure: sorbent system hemodialysis.

A severe metabolic acidosis was produced in a patient with chronic renal failure by hemodialysis using a sorbent system to regenerate bicarbonate dialysate with an initial bicarbonate concentration of 60 mEq/L. The acidosis resolved with standard single-pass hemodialysis. In five additional patients, the bicarbonate concentration of the dialysate with the sorbent system was noted to be low and quite variable (mean +/- SD, 16.5 +/- 8.3 mEq/L, range 5 mEq/L to 39 mEq/L). The low dialysate bicarbonate failed to correct metabolic acidosis and, in fact, was capable of further lowering the serum bicarbonate. The capacity of the regenerating cartridge to release protons makes this form of dialysis a potential cause for metabolic acidosis. The safety of the sorbent system dialysis, at least in the bicarbonate mode, requires further evaluation.

Absorption↗
PubMed2001

Lactic acidosis: pathophysiology, diagnosis and treatment.

Lactic acidosis is common in severely ill patients. We describe four patients with a lactic acidosis combined with other acid-base disturbances. In daily practice it is important to consider these combined disturbances since there is no specific treatment in lactic acidosis. Treating the underlying causes of the acid-base disturbances is the only warranted intervention. However, lactic acidosis is still associated with high mortality.

Acidosis, Lactic↗
PubMed1980

The effect of systemic acidosis on perfusion of replanted extremities.

By measuring skin temperature and muscle pH of replanted rat legs, we found that uncorrected systemic acidosis had a detrimental effect on perfusion of the replanted extremity. Following administration of systemic sodium bicarbonate and correction of acidosis, muscle pH and skin temperature returned to normal with 60 minutes after revascularization. Metabolic acidosis following major extremity replantation and respiratory acidosis after prolonged anesthesia for digital replantation(s) must be corrected to ensure optimal perfusion of the distal capillary bed.

Acidosis↗
PubMed1999

Metabolic acidosis in calves.

In neonatal calves metabolic acidosis is a common sequela to diarrhea-induced dehydration and endotoxemia in the aftermath of gram-negative bacterial infections. Without treatment, metabolic acidosis is a prime factor in the death of many of these calves. This article begins with a general discussion about the causes and recognition of metabolic acidosis. The remaining sections detail the subjective and objective methods available to assess the severity of acidosis and treatment options for this metabolic condition.

Acidosis↗
PubMed1991

[Should metabolic acidosis be alkalinized?].

At present, the administration of bicarbonate for metabolic acidosis has become controversial with regard to the indications and the modalities of treatment. Scientific evidence of the therapeutic value of bicarbonate is still lacking. In the opposite, there is a strong evidence of its adverse effects, such a paradoxical acidosis, sodium load and over all a worsening of haemodynamic status. Other therapeutic measures are limited. They include the administration of Carbicarb which does not increase the CO2 content, haemodialysis with bicarbonate and/or hyperventilation. As for every therapeutic action, the treatment must rely on an interpretation of the pathophysiological mechanism, resulting in the definition of therapeutic goals. The amendment of acidosis is not always a therapeutic priority. In ketoacidosis for instance, the depth of acidosis is mainly related to the degree of dehydration, the treatment of which results in a normalization of pH.

Acidosis↗
PubMed2002

Effects of regional hypoxia and acidosis on Rb(+) uptake and energetics in isolated pig hearts: (87)Rb MRI and (31)P MR spectroscopic study.

The study compared the effects of regional hypoxia and acidosis on Rb(+) uptake and energetics in isolated pig hearts perfused by the Langendorff method. The left anterior descending artery (LAD) was cannulated and the LAD bed was perfused with the same specific flow as the whole heart. Following equilibration with normal Krebs-Henseleit buffer (KHB, pO(2) 568 mm Hg, pH 7.42) the perfusate was switched to one that contained Rb(+) (Rb-KHB). Simultaneously, perfusion through the LAD was carried out with hypoxic (pO(2)=31 mm Hg), an acidemic (pH 7.12) or normal (pO(2)=550 mm Hg) Rb-KHB for 120 min. (87)Rb images of the entire heart or localized (31)P spectra from the left ventricular anterior wall were acquired. Hypoxia decreased the maximal (87)Rb image intensity and Rb(+) flux in the anterior wall to 79+/-9% and 85+/-7%, respectively, of that in the posterior wall. Extracellular acidosis did not affect (87)Rb image intensity and reduced Rb(+) flux (83+/-10%). During hypoxia phosphocreatine and ATP decreased to 36+/-10 and 50+/-15% of baseline, respectively and intracellular pH (pHi) decreased to 6.90+/-0.05. Extracellular acidosis did not affect the phosphocreatine or ATP levels but reduced pHi (7.06+/-0.18 vs. 7.26+/-0.06 in control). We suggest that intracellular acidosis plays a role in the inhibition of Rb(+) uptake during hypoxia.

Acidosis↗
PubMed1996

Metabolic acidosis and fetal reserve.

Dr Bailey, Director of the National Institute of Neurological Diseases and Blindness, Bethesda, Maryland, introduced the 1956 symposium on 'Neurological and psychological deficits of asphyxia neonatorum' by saying. 'Medical research in regard to cerebral palsy and other neurological disabilities has been relatively neglected. For a truly comprehensive attack on this problem we must focus a sharper scientific search for greater knowledge of those adverse biological factors which operate in the perinatal period. The proper point of departure in such a search is through controlled animal observations, for which purpose monkeys are best suited' (Windle, 1958). Our understanding of the significance of asphyxia is built on the foundation of the laboratory research that has followed upon this initiative. Laboratory studies in fetal monkeys and fetal lambs have clearly demonstrated that the fetus can initially compensate for an asphyxial insult and protect the vital organs. However, if the hypoxaemia progresses to a severe metabolic acidosis and cardiovascular decompensation with hypotension, brain damage will occur. There is a growing body of clinical evidence that supports the contention that the human fetus responds in a similar manner. The varied nature of hypoxic and ischaemic insults has been well demonstrated in animal studies. Total anoxia and isolated cerebral ischaemia are uncommon events in the human fetus. The common insult, particularly during labour, is a degree of hypoxia present over a variable period of time. This is fortunate in that such insults are associated with a period of fetal compensation that may last several hours, during which time a diagnosis of a developing metabolic acidosis can be made. This is the clinician's window of opportunity, when a definitive diagnosis of an asphyxial insult can be made and if necessary intervention made before the threshold of decompensation has been reached. A consensus on the threshold of decompensation has yet to be achieved. However, there is a growing body of evidence that the threshold is in the range of an umbilical artery base deficit of 12-16 mmol/l. Since the aim of the obstetrician during labour is the prevention of asphyxial morbidity and mortality, the determination of this threshold is important to provide criteria for clinical action. A blood gas and acid-base assessment with the determination of a metabolic acidosis is the best measure of an asphyxial insult that may be of clinical significance. The definition of the threshold of metabolic acidosis requiring intervention will continue to be clarified with future clinical research. However, there are many factors that will influence the fetal response to an asphyxial insult, which may require that a range of threshold be acknowledged. The effect upon the fetus will be influenced by whether the asphyxial event is the first or the last of a series of asphyxial episodes, and the duration of the asphyxial episode. The characteristics of the fetus, i.e. maturity (pre-term versus term), and fetal growth small for gestational age (SGA) or appropriate for gestational age (AGA) may influence the fetal response to an asphyxial insult. Improved understanding of these issues will provide a better rationale for clinical management.

Acidosis↗
PubMed2003

Localization and hormonal control of serine dehydratase during metabolic acidosis differ markedly from those of phosphoenolpyruvate carboxykinase in rat kidney.

Serine dehydratase (SDH) is abundant in the rat liver but scarce in the kidney. When administrated with dexamethasone, the renal SDH activity was augmented 20-fold, whereas the hepatic SDH activity was affected little. In situ hybridization and immunohistochemistry revealed that SDH was localized to the proximal straight tubule of the nephron. To address the role of this hormone, rats were made acidotic by gavage of NH(4)Cl. Twenty-two hours later, the SDH activity was increased three-fold along with a six-fold increment in the phosphoenolpyruvate carboxykinase (PEPCK) activity, a rate-limiting enzyme of gluconeogenesis. PEPCK, which is localized to the proximal tubules under the normal condition, spreads throughout the entire cortex to the outer medullary rays by acidosis, whereas SDH does not change regardless of treatment with dexamethasone or NH(4)Cl. When NH(4)Cl was given to adrenalectomized rats, in contrast to the SDH activity no longer increasing, the PEPCK activity responded to acidosis to the same extent as in the intact rats. A simultaneous administration of dexamethasone and NH(4)Cl into the adrenalectomized rats fully restored the SDH activity, demonstrating that the rise in the SDH activity during acidosis is primarily controlled by glucocorticoids. The present findings clearly indicate that the localization of SDH and its hormonal regulation during acidosis are strikingly different from those of PEPCK.

Acidosis↗
PubMed1997

Severe lactic acidosis and neonatal death in Pearson syndrome.

Pearson marrow-pancreas syndrome, a fatal disease associated with mitochondrial DNA rearrangements, is characterized by refractory sideroblastic anaemia during infancy. Only a few neonates with Pearson syndrome have been reported with metabolic acidosis. A female neonate who exhibited severe metabolic acidosis and anaemia at birth is described here. Her condition progressively worsened, with pancytopenia and uncontrollable metabolic acidosis resulting in death at the age of 14 days. A 4988-base pair deletion of mtDNA was detected in the patient's leukocytes, liver and muscle. When a neonate exhibits severe metabolic acidosis of unknown cause, the possibility of Pearson syndrome should be considered.

Acidosis, Lactic↗
PubMed1991

Glucose starvation and acidosis: effect on experimental metastatic potential, DNA content and MTX resistance of murine tumour cells.

Exposure to oxygen deprivation in vitro has been reported to cause drug resistance in CHO cells (Rice et al., 1986; PNAS 83, 5978) and enhancement of experimental metastatic (colonisation) ability of murine tumour cells (Young et al., 1988; PNAS 85, 9533). Both these studies also demonstrated the induction of a subpopulation of cells with excess DNA content. Since the micromilieu in tumours results in exposure of the tumour cells to conditions of acid pH and nutrient deprivation, as well as hypoxia, we have examined the effect of exposure to acidosis (pH 6.5) and glucose starvation on drug resistance, cellular DNA content and the experimental metastatic ability of KHT sarcoma and B16F1 melanoma cells. Cells were exposed to these conditions for 24 and 48 h and tested for resistance to methotrexate (MTX) or experimental metastatic ability either immediately following these exposures or after 24 or 48 h of recovery in normal growth medium. Both cell lines demonstrated an enhancement of colonisation potential, which was most marked when cells were injected after 48 h of exposure followed by a 24 or 48 h recovery period. Flow cytometric analysis demonstrated an increase in the fraction of KHT cells with excess DNA following both glucose starvation and acidosis we observed only a small increase in MTX resistance following acidic exposure of cells and no change following glucose starvation. Since both acidosis and glucose starvation are known to induce glucose regulated proteins (grp), a subset of the stress protein family, we studied the effect of treatment with another known inducer, 2-deoxyglucose. We found that this agent affected the metastatic efficiency of KHT cells in a manner similar to that observed following exposure to glucose starvation and acidosis. However, further studies are required to establish what role, if any, grp play in this effect. In conclusion this study shows that transient exposure of murine tumour cells to an acidic or glucose deprived environment can cause progression in terms of metastatic potential.

Acidosis↗
PubMed1991

Acidosis-induced ischemic brain damage: are free radicals involved?

Substantial evidence exists that reactive oxygen species participate in the pathogenesis of brain damage following both sustained and transient cerebral ischemia, adversely affecting the vascular endothelium and contributing to the formation of edema. One likely triggering event for free radical damage is delocalization of protein-bound iron. The binding capacity for some iron-binding proteins is highly pH sensitive and, consequently, the release of iron is enhanced by acidosis. In this study, we explored whether enhanced acidosis during ischemia triggers the production of reactive oxygen species. To that end, enhanced acidosis was produced by inducing ischemia in hyperglycemic rats, with normoglycemic ones serving as controls. Production of H2O2, estimated from the decrease in catalase activity after 3-amino-1,2,4-triazole (AT) administration, was measured in the cerebral cortex, caudoputamen, hippocampus, and substantia nigra (SN) after 15 min of ischemia followed by 5, 15, and 45 min of recovery, respectively (in substantia nigra after 45 min of recovery only). Free iron in cerebrospinal fluid (CSF) was measured after ischemia and 45 min of recovery. Levels of total glutathione (GSH + GSSH) in cortex and hippocampus, and levels of alpha-tocopherol in cortex, were also measured after 15 min of ischemia followed by 5, 15, and 45 min of recovery. The results confirm previous findings that brief ischemia in normoglycemic animals does not measurably increase H2O2 production in AT-injected animals. Ischemia under hyperglycemic conditions likewise failed to induce increased H2O2 production. No difference in free iron in CSF was observed between animals subjected to ischemia under hyper- and normoglycemic conditions. The moderate decrease in total glutathione or alpha-tocopherol levels did not differ between normo- and hyperglycemic animals in any brain region or at any recovery time. Thus, the results failed to give positive evidence for free radical damage following brief periods of ischemia complicated by excessive acidosis. However, it is possible that free radical production is localized to a small subcellular compartment within the tissue, thereby escaping detection. Also, the results do not exclude the possibility that free radicals are pathogenetically important after ischemia of longer duration.

Acidosis↗
PubMed1983

Secondary hypocapnia fails to protect "whole body" intracellular pH during chronic HCl-acidosis in the dog.

Studies have demonstrated that the protective effect of secondary hypocapnia on plasma acidity during chronic HCl-acidosis is undermined by a renal-mediated decrement in plasma bicarbonate concentration induced by the hypocapnia itself. The present study was designed to assess whether the protection of "whole body" intracellular pH (pHi) is similarly undermined by this maladaptive response of the kidney. Whole body pHi was estimated by the 5,5 dimethyl-2,4-oxazolidinedione (DMO) method in seven unanesthetized dogs under each of three conditions: control, chronic HCl-acidosis (10 mEq H+/kg/day) with spontaneous secondary hypocapnia, and chronic HCl-acidosis with a normal level of carbon dioxide tension (maintained by the use of an environmental chamber). pHi was 6.71 +/- 0.02 during control, and 6.57 +/- 0.03 and 6.57 +/- 0.02 during the two acidosis periods, respectively. These results indicate that sustained secondary hypocapnia fails to render the intracellular compartment less acidic because of a maladaptive reduction in intracellular bicarbonate concentration.

Acidosis↗