Variability of the Methionine Loading Test: No Effect of a Low Protein Diet

Author(s):  
Martin den Heijer ◽  
Gerard M J Bos ◽  
Ingeborg A Brouwer ◽  
Wim B J Gerrits ◽  
Henk J Blom

The methionine loading test is used for the diagnosis of impaired methionine/homocysteine metabolism, in particular the transsulfuration pathway. Usually this test is performed on a low protein diet to control the intake of methionine. However, this is inconvenient and relatively expensive. In this study we compared the effects of a low protein diet and a standard diet on methionine loading test in 28 subjects (crossover design). The mean difference in homocysteine concentration after methionine loading between the two diets was 1.3 [confidence interval (CI) 95%-1.0–3.6]μmol/L which demonstrates that a special low protein diet is not essential in the performance of the methionine loading test. We also observed that 3 weeks after the first methionine loading test, fasting serum concentration of folate was higher and vitamin B12 concentration was lower.

1995 ◽  
Vol 88 (1) ◽  
pp. 29-37 ◽  
Author(s):  
Tsukasa Nakamura ◽  
Mitsumine Fukui ◽  
Isao Ebihara ◽  
Shiori Osada ◽  
Toshimasa Takahashi ◽  
...  

1. The present study was designed to assess whether glomerular expression of mRNAs for endothelin-1 and endothelin-3, as well as endothelin receptors A and B is affected by a low-protein diet during the course of focal glomerular sclerosis. 2. Focal glomerular sclerosis was induced in rats by injection of puromycin aminonucleoside on days 0, 27, 34 and 41 in conjunction with unilateral nephrectomy on day 22. Control rats were subjected to nephrectomy or sham operation on day 22. 3. Animals were divided into six groups. In group 1, the puromycin aminonucleoside-injected rats were fed a standard diet containing 22% protein. In group 2, the puromycin aminonucleoside-injected rats were fed a low-protein diet containing 6% protein, which was initiated on the day of the first puromycin aminonucleoside injection. In group 3, the nephrectomized rats without puromycin aminonucleoside were fed a standard diet. In group 4, the nephrectomized rats without puromycin aminonucleoside were fed a low-protein diet. In group 5, the sham-operated rats were fed a standard diet. In group 6, the sham-operated rats were fed a low-protein diet. 4. The percentage of sclerotic glomeruli in group 1 rats increased markedly with time, reaching 77% on day 80. 5. The glomerular mRNA levels for endothelin-1 and endothelin receptors A and B increased significantly as glomerular sclerosis progressed, whereas no endothelin-3 mRNA was detected in the glomeruli of any group. 6. The endothelin-1 production in isolated glomeruli from group 1 increased significantly as glomerular sclerosis progressed. 7. In group 2, the low-protein diet reduced the prevalence of glomerular sclerosis, attenuated the rise in mRNA levels for endothelin-1 and endothelin receptors A and B and reduced endothelin-1 production in glomeruli from rats with focal glomerular sclerosis. 8. These data indicate that increases in glomerular endothelin-1 and endothelin receptor mRNA levels are associated with the development of puromycin aminonucleoside-induced glomerular sclerosis. These effects are blunted by administration of a low-protein diet.


1986 ◽  
Vol 23 (5) ◽  
pp. 610-618 ◽  
Author(s):  
P. H. Berry

Hypophyses of four groups of 50 female rats (F0—nulliparous, F0—multiparous, F1—standard diet, and F1—low protein) were examined by light microscopy and immunocytochemistry by the avidin-biotin complex method. In pituitary glands of rats fed a low protein diet, the incidence of neoplasms of the pars distalis, the number of multifocal tumors, and the degree of neoplastic cellular atypia were significantly reduced. Pituitary adenomata in rats fed a low protein diet also caused significantly less brain compression at the time of necropsy than in rats fed a standard diet. All but two neoplastic foci from the 83 tumors stained for prolactin, and 14 of these also stained for growth hormone. No differences were found in the frequency of hemorrhagic or solid patterns of tumor. These findings may reflect a reduction in pituitary tumor initiation, promotion, and/or progression in rats fed a low protein diet.


2021 ◽  
pp. 039139882110498
Author(s):  
Kullaya Takkavatakarn ◽  
Piyawan Kittiskulnam ◽  
Khajohn Tiranathanagul ◽  
Pisut Katavetin ◽  
Niramon Wongyai ◽  
...  

Incremental hemodialysis (HD) has become an exciting approach according to the recognition of the importance of preserving residual kidney function (RKF). However, not all incident HD patients are suitable for this approach, particularly once-weekly HD. This is the first study which reported the effectiveness of once-weekly online-hemodiafiltration (OL-HDF) plus low protein diet (LPD) in incident HD patients. All stage 5 CKD patients who had chosen HD as their treatment modality at the HD center of King Chulalongkorn Memorial Hospital, Bangkok, Thailand, with RKF ⩾ 3 mL/min calculated by renal clearance of urea and urine output ⩾ 800 mL/day, started the treatment with once-weekly OL-HDF. Dietitians advised patients to consume LPD (0.6–0.8 g/kg/day) on non-dialysis days and a regular protein diet on the dialysis day (1.2 g/kg/day). Eleven incident HD patients were enrolled in the study. The mean RKF and urine volume at baseline were 4.56 ± 2.21 mL/min and 2,019.54 ± 743.73 mL/day, respectively. After 6 and 12 months of follow-up, the mean RKF of the patients who remained in the once-weekly OL-HDF protocol were 3.82 ± 1.68 mL/min and 3.28 ± 0.95 mL/min, respectively. The median duration of once-weekly OL-HDF before transitioning to twice- or thrice-weekly OL-HDF was 7 months (3–24 months). The most common indication for stepping prescription was too low RKF. We reported that dialysis initiation in the university-based center with once-weekly OL-HDF in carefully selected incident HD patients combined with LPD under serial monitoring is practical. Further studies on the clinical benefits of once-weekly OL-HDF are still required.


1970 ◽  
Vol 24 (1) ◽  
pp. 11-22 ◽  
Author(s):  
O. Faruque ◽  
D. M. Walker

1. The mean liver retinol reserve (retinal + retinyl esters, expressed as retinol) of six newborn lambs was 21±8 μg. The mean value for ten suckled lambs, aged 5–7 days, was 2655±472 μg retinol per liver.2. Three unsuckled lambs were fed ad lib. from birth for 28 days on a high-protein diet, based on lard and skim milk, without supplementary vitamin A. The diet provided sufficient vitamin A for normal growth, but insufficient to permit substantial liver reserves (43±8 μg retinol per liver).3. Thirty-six suckled lambs aged 5–7 days were given either a low-or a high-protein diet for 21 days, with or without graded levels of retinyl acetate or βcarotene. There were no significant differences in the live-weight gain or in liver retinol reserves between the low-and highprotein dietary treatments, or between the supplemented and unsupplemented groups.4. Twelve lambs were pair-fed on either a low-or a high-protein diet from birth for 21 days. Six lambs that were given a large supplement of retinyl palmitate on the 1st day of life had stored significantly less retinol in the liver at 21 days (P > 0.01) than six lambs given a somewhat smaller total amount of retinyl palmitate in small daily doses. Lambs given the high-protein diet had significantly greater liver retinol reserves (P > 0.01) than lambs given the low-protein diet, with both methods of supplementation.5. Twelve lambs were pair-fed from birth on a high-protein diet for 2 or 6 days. Lambs that were given retinyl palmitate dissolved in either a low-or a high-protein diet on the 1st day of life had significantly lower liver retinol reserves some 24 h later (P > 0.01) than lambs given similar treatments on the 5th day of life. Liver retinol reserves were positively correlated with the protein concentration of the diet at the time of supplementation.6. Eighteen lambs were pair-fed from birth with either a low- or a high-protein diet. Six pairs were given retinyl palmitate daily and three pairs were given the supplement 48 h before slaughter. The source of protein was casein. Eight out of nine lambs given the low-protein diet would have died had they not been slaughtered at between 8 and 11 days of age. The time of supplementation had no significant effect on liver retinol reserves, which were very low, regardless of the dietary protein concentration. Lambs given the high-protein diet retained a significantly greater proportion (P > 0.05) of the dietary retinyl palmitate than lambs given the low-protein diet.


2021 ◽  
Vol 8 ◽  
Author(s):  
Garrett J. Mullenix ◽  
Elizabeth S. Greene ◽  
Nima K. Emami ◽  
Guillermo Tellez-Isaias ◽  
Walter G. Bottje ◽  
...  

Proteins are considered the most expensive nutrients in commercial modern broiler production, and their dietary inclusion at low levels is pivotal to minimize feed costs and reduce nitrogen waste. The quest for an environmentally friendly source of proteins that favor the formulation of low protein diets without compromising broiler health, welfare, and growth performance has become a hotspot in nutrition research. Due to its high protein content, the naturally growing Spirulina microalgae is considered a promising nutrient source. The purpose of the present study was, therefore, to determine the effects of Spirulina supplementation on liver bacterial translocation, hematological profile, and circulating inflammatory and redox markers in broilers fed a low-protein diet. One-day-old Ross 708 male broilers (n = 180) were randomly assigned into one of three experimental treatments: standard diet as a control, low protein diet, and low protein diet supplemented with 100 g/kg of Spirulina. Target molecular markers were measured in the peripheral blood circulation using real-time quantitative PCR. Reducing dietary proteins increased bacterial translocation and systemic inflammation as indicated by proportions of basophils among blood leukocytes. The expression levels of circulating pro-inflammatory cytokines [interleukin (IL)-3, IL-6, IL-4, IL-18, and tumor necrosis factor-α], chemokines (CCL-20), and NOD-like receptor family pyrin domain containing 3 inflammasome were significantly upregulated in birds fed the low protein diet compared with the control. The inclusion of Spirulina reversed these effects, which indicates that Spirulina reduces systemic inflammation- and bacterial translocation-induced by a low protein diet and could be a promising alternative protein source in poultry diets.


Author(s):  
F. G. Zaki

Addition of lithocholic acid (LCA), a naturally occurring bile acid in mammals, to a low protein diet fed to rats induced marked inflammatory reaction in the hepatic cells followed by hydropic degeneration and ductular cell proliferation. These changes were accompanied by dilatation and hyperplasia of the common bile duct and formation of “gallstones”. All these changes were reversible when LCA was withdrawn from the low protein diet except for the hardened gallstones which persisted.Electron microscopic studies revealed marked alterations in the hepatic cells. Early changes included disorganization, fragmentation of the rough endoplasmic reticulum and detachment of its ribosomes. Free ribosomes, either singly or arranged in small clusters were frequently seen in most of the hepatic cells. Vesiculation of the smooth endoplasmic reticulum was often encountered as early as one week after the administration of LCA (Fig. 1).


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