Keto-supplemented Low Protein Diet: A Valid Therapeutic Approach for Patients with Steroid-resistant Proteinuria during Early-stage Chronic Kidney Disease

BACKGROUND AND OBJECTIVES

Low protein diets supplemented with keto acid (sLPD) are recommended for patients with stage 3-5 chronic kidney disease (CKD). This study assessed whether sLPD is beneficial for patients with steroid-resistant proteinuria during early-stage CKD.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

A 1-year randomized controlled trial was conducted from 2010 to 2012. In this study, 108 proteinuric patients who were steroid-resistant were assigned to a sLPD group (0.6 g/kg/d with 0.09 g/kg/d keto acids) or a normal protein diet group (NPD, 1.0 g/kg/d). Estimated dietary protein intake, urinary protein excretion, remission rate, renal function, nutritional status, and blood pressure were measured.

RESULTS

Baseline characteristics were comparable between the sLPD group (47 patients) and the NPD group (49 patients). Urinary protein excretion significantly decreased in sLPD compared to NPD in months 6, 9, and 12 (P<0.05). Proteinuria reduction was higher in sLPD than in NPD (P<0.001) at the end of the study. Complete remission and partial remission rates were higher in sLPD than in NPD. Serum albumin and pre-albumin levels were higher in sLPD than in NPD in months 9 and 12 (P<0.05). Serum total cholesterol and triglyceride levels declined more significantly in sLPD than in NPD (P<0.01) at the end of the study. There were no differences in nutritional status, renal function, hemoglobin, or blood pressure between the two groups.

CONCLUSIONS

sLPD is both nutritionally safe and beneficial, providing nephroprotective effects for early-stage CKD patients with steroid-resistant proteinuria.

Pharmacological evidence that alpha-ketoisovaleric acid induces convulsions through GABAergic and glutamatergic mechanisms in rats

Neurological dysfunction is common in patients with maple syrup urine disease (MSUD). However, the mechanisms underlying the pathophysiology of this disorder are poorly known. In the present study we investigated the effect of intrastriatal administration of the alpha-keto acids accumulating in MSUD on the behavior of adult rats. After cannula placing, rats received unilateral intrastriatal injections of alpha-ketoisocaproic acid (KIC, 8 micromol), alpha-ketoisovaleric acid (KIV, 8 micromol), alpha-keto-beta-methylvaleric acid (KMV, 6 micromol) or NaCl. KIV elicited clonic convulsions in a dose-response manner, whereas KIC and KMV did not induce seizure-like behavior. Convulsions provoked by KIV were prevented by intrastriatal preadministration of muscimol (46 pmol) and MK-801 (3 nmol), but not by the preadministration of DNQX (8 nmol). These results indicate that among the keto acids that accumulate in MSUD, KIV is the only metabolite capable of causing convulsions in the present animal model and indicates that KIV is an important excitatory metabolite. Moreover, the participation of GABAergic and glutamatergic NMDA mechanisms in the KIV-induced convulsant behavior is suggested, since KIV-induced convulsions are attenuated by muscimol and MK-801. The authors suggest that KIV may play an important role in the convulsions observed in MSUD, and highlight its relevance to the understanding of the pathophysiology of the neurological dysfunction of MSUD patients.

L-648,051, a novel cysteinyl-leukotriene antagonist is active by the inhaled route in man

1. We have studied some of the pharmacological properties of inhaled L-648,051 which has been shown to be a selective cysteinyl-leukotriene (LT) antagonist in vitro and in vivo in various animal models. 2. The effects of three different doses (1.6, 6.0 and 12.0 mg) on the bronchoconstriction induced by inhaled LTD4 have been investigated in normal male subjects in a series of double-blind, placebo controlled studies. Furthermore, the specificity of the drug has been investigated by challenging subjects with histamine after pre-inhalation of 12.0 mg L-648,051. 3. At all doses L-648,051 partially blocked the bronchoconstriction induced by LTD4 inhalation in a dose related manner. At a dose of 12.0 mg, L-648,051 decreased the maximum fall in specific airways conductance (sGaw) (placebo, 49% vs L-648,051, 21%, P less than 0.01) and shortened the time to recovery from LTD4-induced bronchoconstriction (placebo, 41 min vs L-648,051, 19 min, P less than 0.01). 4. There was no evidence of partial agonist activity, and no effect on histamine-induced bronchospasm. Inhaled L-648,051 at all doses was well tolerated. 5. We conclude that LT antagonism is possible by the inhaled route in man. Inhaled L-648,051 is an active and selective LT-antagonist in man which is well tolerated and may prove to be a useful drug for assessing the role of leukotrienes in asthma and other lung diseases.

Nitrogen balance studies in patients with uremia during treatment with protein-reduced diet and supplementation with essential amino acids or keto acids

Nitrogen balance was studied in 4 patients with uremia during treatment with a protein-reduced diet (20 g) supplemented with either essential amino acids and histidine or a mixture of keto analogues of five of the essential amino acids and essential amino acids. 3 patients completed the study. Nitrogen balance was negative on the diet only and was improved with both forms of supplementation. However, supplementation with the keto acids did not offer any advantage over the conventional essential amino acid supplementation. 1 patient developed serious hypercalcemia during treatment with the keto acid supplementation.

Changes in serum calcium caused by supplementation of low protein diets with keto-acid analogues in patients with chronic renal failure

Six patients with stable end stage chronic renal failure have been studied while receiving keto-acid supplements that provided a daily calcium load of 42 +/- 2 mM. None of the patients had intercurrent illness. All patients showed elevated serum calcium concentration levels while on keto-acid supplements, reaching significance on 5 occasions. Reciprocal falls in serum phosphate concentrations were noted in all patients, and this observation was not due to an anabolic effect of the keto-acids. In 3 patients, the rise in serum calcium concentration was associated with marked clinical manifestations that required curtailment of treatment. The risk of hypercalcemia occurs early and certain high risk categories can be identified. Recommendations about the use of calcium salts of alpha-keto-acid analogues are given and it is suggested that a choice should be made available between calcium and sodium salt analogues.