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C Ichai

Publications and source records attributed to C Ichai.

At least 19 recordsLinked to original sources

[Metformin-associated lactic acidosis].

OBJECTIVE: The aims of this review are to precise the pathophysiological mechanisms leading to biguanide-associated lactic acidosis, to give elements of diagnosis, and to underline the precautionary conditions for prescribing these drugs by an improvement in physicians and patient's education. DATA SOURCES: A PubMed database research in English and French language reports published until December 2005. The keywords were: lactic acidosis, metformin, biguanide, diabetes mellitus. DATA EXTRACTION: Data in selected articles were reviewed, clinical and basic science research relevant informations were extracted. DATA SYNTHESIS: Metformin, which is an oral antidiabetic agent, is the only one biguanide available in France. It acts by enhancing the sensitivity to insulin by a decrease in the hepatic glucose production and an increase in its peripheral use. In term of glycemic control, it has the same efficiency than the other hypoglycemic agents. It represents the treatment of choice for overweight type 2 diabetic patients because of its beneficial effects on the weight loss and on the cardiovascular complications. The incidence of metformin-associated lactic acidosis is very low when contra-indications and appropriate rules for prescribing this drug are respected. The relationship between metformin and lactic acidosis remains largely controversial. In practical, we can distinguish three situations which have different prognosis. In the first case, metformin seems to be responsible for lactic acidosis because of self-poisoning or accidental overdose, and prognosis is good. In the second case, the association between metformin and lactic acidosis is coincidental rather than causal, and may be induced by an underlying organ failure. In the last case there is a cause of lactic acidosis which is worsened by a precipitating factor leading to metformin accumulation. The 2 latter situations are very severe as mortality rate is about 50%. Symptomatic treatments and renal replacement therapy which allows metformin removal are the curative treatment. Prevention is essential. It requires the respect of metformin contraindications and a better education of physicians and patients for a safe prescription. CONCLUSION: Due to its beneficial effects, metformin is the gold standard treatment for overweight type 2 diabetic patients. The essential precautionary conditions for prescribing metformin as well as the respect of its contra-indications permit largely to prevent lactic acidosis. This complication is serious when it is associated with intercurrent illnesses and metformin accumulation. The curative treatment is based on renal replacement therapy. Prevention only rests on the respect of the contra-indications. Education of physicians and patients concerning the rules of prescription remains essential.

Acidosis, Lactic↗

Effects of acetylcysteine and ischaemic preconditioning on muscular function and postoperative pain after orthopaedic surgery using a pneumatic tourniquet.

BACKGROUND AND OBJECTIVE: The use of a pneumatic tourniquet can induce muscular and neurological complications in the operated limb. The genesis of these injuries could involve an ischaemia/reperfusion phenomenon and a compression under the cuff. We evaluated effects of an antioxidant, acetylcysteine and ischaemic preconditioning on the rhabdomyolysis and postoperative pain following a knee ligamentoplasty using a pneumatic tourniquet. METHODS: We included 31 patients scheduled for a knee ligamentoplasty randomly assigned in three groups (control, acetylcysteine 1200 mg the day before and 600 mg at the operative day, ischaemic preconditioning). RESULTS: There was a moderate rise in myoglobin and creatinine phosphokinase with no significant difference between the three groups. The muscular functional parameters were similar in all the groups. However, the morphine consumption within the first 48 h was smaller in the treatment groups (0.22 +/- 0.31 mg kg-1 and 0.22 +/- 0.23 mg kg-1 in the preconditioning and antioxidant groups, respectively) than in the control group (0.47 +/- 0.33 mg kg-1, P <0.05). CONCLUSIONS: Acetylcysteine and ischaemic preconditioning do not decrease the extent of rhabdomyolysis related to the use of a pneumatic tourniquet and do not improve the postoperative muscle recovery. On the other hand, they allow a significant reduction in the postoperative morphine consumption.

Acetylcysteine↗

[Septic shock: blood glucose regulation].

Blood glucose regulation is controlled by several hormones, neurological mechanisms and the hepatic autoregulation. Glucose uptake necessitates glucose transporters which are called GLUT. In physiological situation, 80% of glucose uptake of the whole body is produced by the non-insulin dependant tissues, via the GLUT 1 to 3 transporters. Glucose uptake by insulin dependant tissues is mediated by insuline, which activates GLUT-4 transporters. Because of the production of pro-inflammatory mediators (TNF-alpha), sepsis induces hyperglycemia, which results essentially from an hepatic insulinoresistance. This phenomenon leads to an acute load and uptake of glucose by the non-insulin dependant tissues. Hyperglycemia modifies inflammatory and immune reactions and enhances the production of reactive oxygen species. Thus, sepsis has an impact on blood glucose control and conversely. Blood glucose control has been found to decrease mortality and morbidity in critically ill patients. The exact mechanism, by which these beneficial effects are produced, remains controversial, due to euglycemia or to insulin infusion. Probably both mechanisms are implicated. In all cases the beneficial effects seem to be multifactorial: a decrease in oxydative stress, a protective effect in front of the burst suppression, multiple anti-inflammatory effects. The optimum level of blood glucose is still discussed and must be evaluated in further studies. In all cases, blood glucose level must be under or equal to 1,4 g/l. Even no clinical study evaluates precisely the impact of hyperglycemia during sepsis, a lot of arguments supports that blood glucose level must be a therapeutic goal in these situations.

Blood Glucose↗

[Face necrotizing fasciitis following spinocellular epithelioma excision].

Necrotizing fasciitis is a bacterial dermo-hypodermitis with superficial aponevrosis necrosis due to Streptococcus pyogenes. Head and neck region are some rare localization of this infection especially after surgery. We report herein a case of a face necrotizing fasciitis following minor face surgery. A 86 year-old Caucasian male without any antecedents, nor treatment, has been operated for a fronthead spinocellular epithelioma under local anesthesia. Twelve hours later, a severe pain localized to the face occurred, with sleeplessness, followed up with a face orbitary oedema and fever. Twenty-four hours later, an intravenous antibiotherapy was therefore started and surgical treatment was performed as soon as the diagnosis of necrotizing fasciitis was considered. An important inflammatory oedema was noticed, associated to a large necrotic softening of the face, the eyelid and the neck sub-cutaneous tissues. Then, the patient has been transferred in intensive care unit because multi-organ failure clinical and biological signs occurred. Pre-operatory bacteriological samples culture identified Streptococcus pyogenes. Repeated surgical explorations and debridement (excision, cleaning, draining and bandages recovery) were performed daily as needed until all the necrotic tissue was all eradicated. The antibiotherapy was prescribed to totalised 15 days. Our report underlines the importance of an early recognition of the diagnosis of soft tissue infection, because early surgical treatment has a better prognosis and antibiotic treatment alone is inefficient for the recovery. Alert is delivered by the local signs quickly followed up by skin changes. Anti-inflammatory therapy must be avoid in case of any soft tissue infection sign: they may increase the lesions, hide alarm signs and delay surgical treatment.

Aged↗

[Pasteurella multocida meningo-encephalitis with aphasia in a young adult].

We report the first case of Pasteurella multocida meningo-encephalitis with aphasia in a 28 year-old-patient. The investigations confirmed the diagnosis of bacterial meningitis. But the delay in identification of the organism involved iterative changes of antibiotherapy. The evolution was finally favourable with appropriate antibiotic treatment. The epidemiologic investigation highlighted the responsibility of a patient's cat carrying the same bacterial strain. Finally we discuss the epidemiologic, clinical and therapeutic features of this unusual meningitis.

Adult↗

[Secondary Streptococcus pyogenes peritonitis following necrotizing fasciitis].

We report the case of a 66-year-old woman with diabetes mellitus and disseminated lupus treated with immunosupressive drug. She was admitted for an inflammatory oedema of the right lower limb associated to diffuse abdominal pain and vomiting. The occurrence of septic shock with multiple organ failure and surgical abdominal picture led us to perform urgent laparotomy without taking in account the evolutive signs of cutaneous lesions i.e. purpuric elements and haemorrhagic phlycthena. The abdominal cavity exploration showed peritonitis without digestive tracts perforation. The patient died few hours after surgical procedure. All bacteriological samples i.e. peritoneal effusion, blood cultures and phlycthena liquid were positive for Streptocoque pyogenes (group A) and peritonitis was considered to be related to haematogen diffusion from rapid course necrotizing fasciitis.

Aged↗

[Metformin-associated lactic acidosis remains a serious complication of metformin therapy].

We report 4 cases of lactic acidosis in diabetic patients usually treated with metformin. For the first 3 patients, the clinical history was similar because lactic acidosis was precipitated by gastro-intestinal disorders whereas all of them were simultaneously treated with several nephrotoxic drugs. These 3 patients presented with acute renal failure on arrival at hospital. Their issue was fatal whereas any obvious cause of overproduction of lactate was found. The fourth case, which was due to a voluntary intoxication, was the only one presenting with a favourable evolution. The metformin plasma and red blood cell levels were performed for 2 of 4 patients and confirmed the overdose. These observations remind that metformin-associated lactic acidosis remains a serious complication, and that medical doctors must respect strictly contra-indications and guidelines for withdrawing metformin.

Acidosis, Lactic↗

Glucose 6-phosphate hydrolysis is activated by glucagon in a low temperature-sensitive manner.

Glucagon affects liver glucose metabolism mainly by activating glycogen breakdown and by inhibiting pyruvate kinase, whereas a possible effect on glucose-6-phosphatase has also been suggested. Although such a target is of physiological importance for liver glucose production it was never proven. By using a model of liver cells, perifused with dihydroxyacetone, we show here that the acute stimulation of gluconeogenesis by glucagon (10(-7) m) was not related to the significant inhibition of pyruvate kinase but to a dramatic activation of the hydrolysis of glucose 6-phosphate. We failed to find an acute change in glucose-6-phosphatase activity by glucagon, but the increase in glucose 6-phosphate hydrolysis was abolished at 21 degrees C; conversely the effect on pyruvate kinase was not affected by temperature. The activation of glucose 6-phosphate hydrolysis by glucagon was confirmed in vivo, in postabsorptive rats receiving a constant infusion of glucagon, by the combination of a 2-fold increase in hepatic glucose production and a 60% decrease in liver glucose 6-phosphate concentration. Besides the description of a novel effect of glucagon on glucose 6-phosphate hydrolysis by a temperature-sensitive mechanism, this finding could represent an important breakthrough in the understanding of type II diabetes, because glucose 6-phosphate is proposed to be a key molecule in the transcriptional effect of glucose.

Allosteric Site↗

Exogenous Mg-ATP induces a large inhibition of pyruvate kinase in intact rat hepatocytes.

Mg-ATP infusion in vivo has been reported to be beneficial both to organ function and survival rate in various models of shock. Moreover, a large variety of metabolic effects has been shown to occur in several tissues due to purinergic receptor activation. In the present work we studied the effects of exogenous Mg-ATP in rat liver cells perifused with dihydroxyacetone to investigate simultaneously gluconeogenetic and glycolytic pathways. We found a significant effect on oxidative phosphorylation as characterized by a decrease in oxygen consumption rate and in the cellular ATP-to-ADP ratio associated with an increase in lactate-to-pyruvate ratio. In addition, exogenous Mg-ATP induced rapid and reversible inhibition of both gluconeogenesis and glycolysis. The main effect on gluconeogenesis was located at the level of the fructose cycle, whereas the decrease in glycolysis was due to a strong inhibition of pyruvate kinase. Although pyruvate kinase inhibition induced by exogenous Mg-ATP was allosteric when assessed in vitro after enzyme extraction, we found a large decrease in the apparent maximal velocity when kinetics were assessed in vivo in intact perifused hepatocytes. This newly described short-term regulation of pyruvate kinase occurs only in the intact cell and may open new potentials for the pharmacological regulation of pyruvate kinase in vivo.

Adenosine Diphosphate↗

The increase in CO2 production induced by NaHCO3 depends on blood albumin and hemoglobin concentrations.

OBJECTIVE: To evaluate the origin of H+ ions participating in the generation of CO2 coming from sodium bicarbonate infusion during metabolic acidosis. We hypothesized that these H+ ions come from a back-titration of the main non-bicarbonate buffers present in the blood, i. e. the hemoglobin and the albumin, and thus postulated that the rate of CO2 release from a bicarbonate load is dependent on the concentration of these buffers. DESIGN: Prospective clinical and experimental study. SETTING: Surgical intensive care unit of a university hospital. PATIENTS AND MATERIAL: (1) Sixteen stable sedated and artificially ventilated critically ill patients with a mild base deficit. (2) Acidotic human blood (bicarbonate 5 mM, pH 7.0) of hematocrit 5, 10, 20 and 40% regenerated from a mixture of frozen fresh plasma and packed red blood cells. INTERVENTIONS PATIENTS: infusion of 1.5 mmol/kg sodium bicarbonate over 5 min. Regenerated blood: 25 mM sodium bicarbonate load. MEASUREMENTS AND RESULTS PATIENTS: continuous measurement of CO2 production (VCO2) on the expired gas using a metabolic monitor and arterial blood gas analysis before (T0), at the end (T5) and at 10, 30 and 60 min after the beginning of the bicarbonate infusion. The increase in VCO2 was 18 +/- 7% leading to a rise in PaCO2 from 39.6 +/- 2.3 at T0 to 46.2 +/- 2.7 mmHg at T5. The increases in VCO2 and in PaCO2 were significantly correlated to the albumin (r = 0.73, p < 0.005 and r = 0.70, p < 0.005, respectively) and to the hemoglobin (r = 0.51, p < 0.05 and r = 0.65, p < 0.01, respectively) concentrations. Regenerated blood: gas analysis 1 min after the bicarbonate load. The increase in PCO2 was closely related to the hematocrit (Ht) of the blood as it was 15.9 +/- 7.5 mmHg for Ht 5%, 29.0 +/- 9.6 for Ht 10%, 44.2 +/- 5.9 for Ht 20% and 71.0 +/- 3.5 for Ht 40% (n = 5 for each, p < 0.001). CONCLUSIONS: The importance of the release of CO2 from a bicarbonate load is dependent on the concentration of the blood non-bicarbonate buffers. It is therefore likely that the adverse effects of bicarbonate therapy linked to the CO2 generation are more important in patients with high blood albumin and hemoglobin concentrations.

Acidosis↗

Comparison of the renal effects of low to high doses of dopamine and dobutamine in critically ill patients: a single-blind randomized study.

OBJECTIVE: The renal effects of dopamine in critically ill patients remain controversial. Low-dose dobutamine has been reported to improve renal function. We compared the effects of various doses of dopamine and dobutamine on renal function in critically ill patients. DESIGN: Prospective, single-blind, randomized study. SETTING: University hospital, 19-bed multidisciplinary intensive care unit. PATIENTS: Twelve hemodynamically stable patients with mild nonoliguric renal impairment. INTERVENTIONS: Each patient randomly received four different doses of dopamine and dobutamine (placebo, 3, 7, and 12 microg/kg/min). Each infusion lasted for 4 hrs. Cardiac output and systemic hemodynamic variables were measured using a pulmonary arterial catheter at the beginning (HO) and the end (H4) of each infusion. The bladder was emptied at HO and H4 to determine urine volume and to collect samples. MEASUREMENTS AND MAIN RESULTS: The cardiac index increased significantly with both dopamine and dobutamine (p < .001). Mean arterial pressure (MAP) increased, with the maximum effect of 20% seen with 12-microg/kg/min dopamine infusion (p < .01). No change in MAP was seen with dobutamine. Dobutamine infusions did not change any renal variables. Conversely, all dopamine infusions significantly increased diuresis, creatinine clearance, and the fractional excretion of sodium (p < .01). Creatinine clearance increased from 61+/-16.9 (SD) mL/min to a maximum of 85.7+/-30 mL/min at the 7-microg/kg/min dose; fractional excretion of sodium increased from 0.26%+/-0.28% to a maximum of 0.62%+/-0.51% at the 12-microg/kg/min dose (p < .01). During dopamine infusions, there was a significant relationship between MAP and creatinine clearance (p = .018). CONCLUSIONS: At all doses studied, 4-hr infusions of dopamine significantly increased creatinine clearance, diuresis, and the fractional excretion of sodium in stable critically ill patients. Conversely, dobutamine did not modify these variables. Although the level of MAP might partially contribute to the improvement in renal variables, it is more likely that the activation of renal dopamine receptors played a prominent role.

Adrenergic beta-Agonists↗

Prolonged low-dose dopamine infusion induces a transient improvement in renal function in hemodynamically stable, critically ill patients: a single-blind, prospective, controlled study.

OBJECTIVE: To evaluate the length of the effects of long-term (48 hrs), low-dose dopamine infusion on both renal function and systemic hemodynamic variables in stable nonoliguric critically ill patients. DESIGN: Prospective, single-blind, controlled clinical study. SETTING: University hospital, 19-bed multidisciplinary intensive care unit. PATIENTS: Eight hemodynamically stable, critically ill patients with a mild nonoliguric renal impairment (creatinine clearance between 30 and 80 mL/min). INTERVENTIONS: Each patient consecutively received 4 hrs of placebo, followed by a 3 microg/kg/min dopamine infusion during 48 hrs, then a new 4-hr placebo period. We measured cardiac output and other hemodynamic variables by using a pulmonary artery catheter. The bladder was emptied to determine urine volume and to collect urine samples. Measurements were performed at six times: after the initial control of 4 hrs of placebo (C1); after 4 hrs (H4), 8 hrs (H8), 24 hrs (H24), and 48 hrs (H48) of dopamine infusion; and after the second control of 4 hrs of placebo (C2). MEASUREMENTS AND MAIN RESULTS: We saw no significant change in systemic hemodynamic variables with dopamine at all times of infusion. Diuresis, creatinine clearance, and the fractional excretion of sodium (FENa) at C1 and C2 were not different. Urine flow, creatinine clearance, and FENa increased significantly 4 hrs after starting dopamine (for all these changes, p < .01 vs. C1 and C2). The maximum changes were obtained at H8, with an increase of 50% for diuresis, 37% for creatinine clearance, and 85% for FENa (for all these changes, p < .01 vs. C1 and C2). But these effects waned progressively from H24, and both creatinine clearance and FENa at H48 did not differ from control values. CONCLUSIONS: In stable critically ill patients, preventive low-dose dopamine increased creatinine clearance, diuresis, and the fractional excretion of sodium without concomitant hemodynamic change. These effects reached a maximum during 8 hrs of dopamine infusion. But despite a slight persistent increase in diuresis, improvement in creatinine clearance and FENa disappeared after 48 hrs. According to these data, it is likely that tolerance develops to dopamine-receptor agonists in critically ill patients at risk of developing acute renal failure.

APACHE↗

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.

Adult↗

Reliability of anion gap as an indicator of blood lactate in critically ill patients.

OBJECTIVE: To evaluate the sensitivity, specificity, and predictive values of an elevated anion gap as an indicator of hyperlactatemia and to assess the contribution of blood lactate to the serum anion gap in critically ill patients. DESIGN: Prospective study. SETTING: General intensive care unit of a university hospital. PATIENTS: 498 patients, none with ketonuria, severe renal failure or aspirin, glycol, or methanol intoxication. MEASUREMENTS AND RESULTS: The anion gap was calculated as [Na+]-[Cl-]-[TCO2]. Hyperlactatemia was defined as a blood lactate concentration above 2.5 mmol/l. The mean blood lactate concentration was 3.7 +/- 3.2 mmol/l and the mean serum anion gap was 14.3 +/- 4.2 mEq/l. The sensitivity of an elevated anion gap to reveal hyperlactatemia was only 44% [95% confidence interval (CI) 38 to 50], whereas specificity was 91% (CI 87 to 94 and the positive predictive value was 86% (CI 79 to 90). As expected, the poor sensitivity of the anion gap increased with the lactate threshold value, whereas the specificity decreased [for a blood lactate cut-off of 5 mmol/l: sensitivity = 67% (CI 58 to 75) and specificity = 83% (CI 79 to 87)]. The correlation between the serum anion gap and blood lactate was broad (r2 = 0.41, p < 0.001) and the slope of this relationship (0.48 +/- 0.026) was less than 1 (p < 0.001). The serum chloride concentration in patients with a normal anion gap (99.1 +/- 6.9 mmol/l) was comparable to that in patients with an elevated anion gap (98.8 +/- 7.1 mmol/l). CONCLUSIONS: An elevated anion gap is not a sensitive indicator of moderate hyperlactatemia, but it is quite specific, provided the other main causes of the elevated anion gap have been eliminated. Changes in blood lactate only account for about half of the changes in anion gap, and serum chloride does not seem to be an important factor in the determination of the serum anion gap.

Acid-Base Equilibrium↗

[The internal environment and intracranial hypertension].

Intracranial pressure depends on cerebral tissue volume, cerebrospinal fluid volume (CSFV) and cerebral blood volume (CBV). Physiologically, their sum is constant (Monro-Kelly equation) and ICP remains stable. When the blood brain barrier (BBB) is intact, the volume of cerebral tissue depends on the osmotic pressure gradient. When it is injured, water movements across the BBB depend on the hydrostatic pressure gradient. CBV depends essentially on cerebral blood flow (CBF), which is strongly regulated by cerebral vascular resistances. In experimental studies, a decrease in oncotic pressure does not increase cerebral oedema and intracranial hypertension (ICHT). On the other hand, plasma hypoosmolarity increases cerebral water content and therefore ICP, if the BBB is intact. If it is injured, neither hypoosmolarity nor hypooncotic pressure modify cerebral oedema. Therefore, all hypotonic solutes may aggravate cerebral oedema and are contra-indicated in case of ICHT. On the other hand, hypooncotic solutes do not modify ICP. The osmotic therapy is one of the most important therapeutic tools for acute ICHT. Mannitol remains the treatment of choice. It acts very quickly. An i.v. perfusion of 0.25 g.kg-1 is administered over 20 minutes when ICP increases. Hypertonic saline solutes act in the same way, however they are not more efficient than mannitol. CO2 is the strongest modulating factor of CBF. Hypocapnia, by inducing cerebral vasoconstriction, decreases CBF and CBV. Hyperventilation is an efficient and rapid means for decreasing ICP. However, it cannot be used systematically without an adapted monitoring, as hypocapnia may aggravate cerebral ischaemia. Hyperthermia is an aggravating factor for ICHT, whereas moderate hypothermia seems to be beneficial both for ICP and cerebral metabolism. Hyperglycaemia has no direct effect on cerebral volume, but it may aggravate ICHT by inducing cerebral lactic acidosis and cytotoxic oedemia. Therefore, infusion of glucose solutes is contra-indicated in the first 24 hours following head trauma and blood glucose concentration must be closely monitored and controlled during ICHT episodes.

Acidosis, Lactic↗