Different effects of γ-linolenic acid (GLA) supplementation on plasma and red blood cell phospholipid fatty acid composition and calcium oxalate kidney stone risk factors in healthy subjects from two race groups with different risk profiles pose questions about the GLA-arachidonic acid-oxaluria metabolic pathway: pilot study.

Fatty acid (FA) composition of phospholipids in plasma and red blood cells (RBC) can influence calciuria, oxaluria and renal stone formation. In this regard, the ratio of arachidonic acid (AA) and its precursor linoleic acid (LA) appears to be important. Administration of γ-linolenic acid (GLA) has been shown to increase the concentration of dihomo-gamma linoleic acid (DGLA) relative to AA indicating that it may attenuate biosynthesis of the latter. Such effects have not been investigated in race groups having difference stone occurrence rates. Black (B) and white (W) healthy males ingested capsules containing linoleic acid (LA) and GLA, for 30 days. Plasma and RBC total phospholipid (TPL) FA profiles, serum and 24 h urine biomarkers of hypercalciuria and urinary stone risk factors were determined on days 0 and 30. Data were tested for statistical significance using GraphPadInstat version 3.02. Concentration and percentage content of DGLA in plasma TPL increased in W but not in B. Arachidonic acid (AA) did not change in either group. There was no change in calcium excretion in either group but oxalate and citrate excretion increased in W. We suggest that elongation of GLA to DGLA may occur more rapidly than desaturation of DGLA to AA in W and that depressed activity of the enzyme elongase may occur in B. Calciuric and citraturic effects may be dependent on the quantity of LA or on the mass ratio of LA/GLA in the FA supplement. Questions about the mooted DGLA-AA-oxaluria pathway arise. We speculate that there exists a potential for using GLA as a conservative treatment for hypocitraturia. The observation of different responses in B and W indicates that such differences may play a role in stone formation and prevention.

[Study on inhibitory effect of EGCG on Calcium oxalate nephrolithiasis in rats and its related mechanism].

In the study, the inhibitory effect of epigallocatechin gallate (EGCG) on Calcium oxalate nephrolithiasis and its possible mechanism were investigated. The rat Calcium oxalate nephrolithiasis model was induced through the combined oral administration of ethylene glycol and ammonium chloride, which was intervened with EGCG. Rat blood samples were collected to detect blood creatinine (Cr), blood urea nitrogen (BUN) and blood calcium. Rat urine samples were collected to observe and compare 24-hour urine volume, oxalic acid (Ox) and calcium in urine. Renal samples were collected to prepare tissue slices and observe the pathological changes in Calcium oxalate nephrolithiasis. The expression of osteopontin (OPN) in renal tissues was evaluated by Real-time PCR and Western blot. According to the results, compared with normal rats, rats in the nephrolithiasis model showed significant increases in Cr, BUN, urine Calcium, urine Ox and renal OPN expression (P < 0.05), but obvious decrease in 24-hour urine volume (P < 0.05); Compared with rats with nephrolithiasis, those processed with EGCG revealed remarkable declines in Cr, BUN, urine Calcium and urine Ox (P < 0.05), with significant rise in 24-hour urine volume (P < 0.05) in a concentration-dependent manner. Additionally, compared with the control group, nephrolithiasis rats showed significant pathological changes in Calcium oxalate calculus. After ECCG treatment, the renal pathological changes and OPN expression attenuated significantly in a concentration-dependent manner. The results showed that EGCG inhibits the formation of calcium oxalate nephrolithiasis in rats and shows a notable protective effect on renal functions.

The efficacy of antioxidant therapy against oxidative stress and androgen rise in ethylene glycol induced nephrolithiasis in Wistar rats.

Administration of natural antioxidants has been used to protect against nephrolithiasis. Urolithiasis was induced by ethylene glycol (EG) in Wistar rats. For 4 weeks, group 1 (control) was fed with a standard commercial diet. Group 2 received the same diet with 0.75% of EG. Group 3 received EG plus the diet and water added with antioxidant nutrients and lime juice as the dietary source of citrate (EG + AX). Group 4 same as group 3 with no EG in water. For 8 weeks, group 5 was fed the standard diet with EG in water for the first 28 days, followed by no EG. Group 6 received the diet with EG for the first 28 days, followed by discontinuation of EG and addition of antioxidant nutrients. Group 7 were provided the diet with antioxidant nutrients for 8 weeks. Group 8 received the diet with antioxidant nutrients for 4 weeks, followed by antioxidant nutrients with EG for the next 4 weeks. Blood samples were collected and kidneys were removed. The size and the mean number of crystal deposits in EG-treated groups was significantly higher than the EG-treated groups, added with antioxidant nutrients and lime juice. After 4 weeks, the mean concentration of malondialdehyde in group 2 was higher than the group 3, and significantly lower in group 4; and in groups 7 after 8 weeks, as well. After 8 weeks, supplementation developed less mean number of deposits in group 6 as compared to group 5; and in group 8, the crystal deposits was substantially less than either group 2 or group 5 (EG-treated rats). Elevated concentration of androgens (as promoters of the formation of renal calculi) as a result of EG consumption decreased following antioxidant supplementations. Results showed a beneficial effect of antioxidant and provided superior renal protection on treating and preventing stone deposition in the rat kidney.

Relevance of Mediterranean diet and glucose metabolism for nephrolithiasis in obese subjects.

BACKGROUND: Nephrolithiasis is more frequent and severe in obese patients from different western nations. This may be supported by higher calcium, urate, oxalate excretion in obese stone formers. Except these parameters, clinical characteristics of obese stone formers were not extensively explored. AIMS: In the present paper we studied the relationship between obesity and its metabolic correlates and nephrolithiasis. MATERIALS AND METHODS: We studied 478 Caucasian subjects having BMI ≥ 25 kg/m². The presence of nephrolithiasis, hypertension, diabetes mellitus and metabolic syndrome were noted. They underwent measurements of anthropometry (BMI and waist circumference, body composition), serum variables (fasting glucose, serum lipids and serum enzymes) and Mediterranean diet (MedDiet) nutritional questionnaire. RESULTS: 45 (9.4%) participants were stone formers. Subjects with high serum concentrations of triglycerides (≥ 150 mg/dl), fasting glucose (> 100 mg/dl) and AST (>30 U/I in F or >40 U/I in M) were more frequent among stone formers than non-stone formers.Multinomial logistic regression confirmed that kidney stone production was associated with high fasting glucose (OR = 2.6, 95% CI 1.2-5.2, P = 0.011), AST (OR = 4.3, 95% CI 1.1-16.7, P = 0.033) and triglycerides (OR = 2.7, 95% CI 1.3-5.7, P = 0.01). MedDiet score was not different in stone formers and non-stone formers. However, stone formers had a lower consumption frequency of olive oil and nuts, and higher consumption frequency of wine compared with non-stone formers. CONCLUSIONS: Overweight and obese stone formers may have a defect in glucose metabolism and a potential liver damage. Some foods typical of Mediterranean diet may protect against nephrolithiasis.

Association between serum 25-hydroxyvitamin D and nephrolithiasis: the National Health and Nutrition Examination Survey III, 1988-94.

BACKGROUND: The role of vitamin D in kidney stone disease is controversial. Current evidence is inconsistent and existing studies are limited by small sample populations. METHODS: We used the third National Health and Nutrition Examination Survey (NHANES III), a large US population-based cross-sectional study, to determine the independent association between serum 25-hydroxyvitamin D [25(OH)D] concentration and prevalent kidney stone disease in a sample of 16 286 men and women aged 18 years or older. A prevalent kidney stone was defined as self-report of any previous episode of kidney stones. RESULTS: Among 16 286 adult participants, 759 subjects reported a history of previous kidney stones. Concentrations of serum 25(OH)D were not different between stone formers and non-stone formers (mean 29.28 versus 29.55 ng/mL, P = 0.57). Higher 25(OH)D concentration was not associated with increased odds ratio (OR) for previous kidney stones [OR = 0.99; 95% confidence interval (CI) 0.99-1.01] after adjustment for age, sex, race, history of hypertension, diabetes, body mass index, diuretic use and serum calcium. Furthermore, after we divided 25(OH)D concentrations into quartiles, or into groups using clinically significant cut-offs (e.g. 40 and 50 ng/mL), still no significant differences were found in stone formation in group comparisons. CONCLUSIONS: High serum 25(OH)D concentrations are not associated with prevalent kidney stone disease in NHANES III participants. Prospective studies are needed to clarify the relationship between vitamin D and kidney stone formation, and whether nutritional vitamin D supplementation will increase risk of stone recurrence.

[The role of alimentary magnesium deficiency in development of nephrolithiasis and its correction with magnesium salts in rats].

Aims of our work were to appraise the quantity and nature of renal calcifications and mineral metabolism in the magnesium-deficient rats; and to find out whether the combination of pyridoxine with Mg L-aspartate or Mg chloride will reduce the length of the treatment needed to recover rats from magnesium deficient condition and urolithiasis state. To induce hypomagnesemia, fifty rats were placed on a magnesium-deficient diet (magnesium content < or = 15 mg/kg) and demineralized water for 10 weeks. On the forty-ninth day of magnesium-deficient diet, rats were treated one of the six supplementations: MgCl2, Mg-L-Asp or their combinations with pyridoxine hydrochloride, magnesium sulfate, magne B6.

Lemon juice has protective activity in a rat urolithiasis model.

BACKGROUND: The use of herbal medicines (medicinal plants or phytotherapy) has recently gained popularity in Europe and the United States. Nevertheless the exact mechanism of the preventive effects of these products is still far to be clearly established, being its knowledge necessary to successfully apply these therapies to avoid stone formation. METHODS: The effect of oral lemon juice administration on calcium oxalate urolithiasis was studied in male Wistar rats. Rats were rendered nephrolithic by providing drinking water containing 0.75% ethylene glycol [v/v] (EG) and 2% ammonium chloride [w/v] (AC) for 10 days. In addition to EG/AC treatment, three groups of rats were also gavage-administered solutions containing 100%, 75% or 50% lemon juice [v/v] (6 microl solution/g body weight). Positive control rats were treated with EG/AC but not lemon juice. Negative control rats were provided with normal drinking water, and were administered normal water by gavage. Each group contained 6 rats. After 10 days, serum samples were collected for analysis, the left kidney was removed and assessed for calcium levels using flame spectroscopy, and the right kidney was sectioned for histopathological analysis using light microscopy. RESULTS: Analysis showed that the rats treated with EG/AC alone had higher amounts of calcium in the kidneys compared to negative control rats. This EG/AC-induced increase in kidney calcium levels was inhibited by the administration of lemon juice. Histology showed that rats treated with EG/AC alone had large deposits of calcium oxalate crystals in all parts of the kidney, and that such deposits were not present in rats also treated with either 100% or 75% lemon juice. CONCLUSION: These data suggest that lemon juice has a protective activity against urolithiasis.