180 Indian Journal of Public Health Research & Development, April-June 2018, Vol.9, No. 2 C is a cofactor in at least eight enzymatic reactions,
including several collagen synthesis reactions that, when dysfunctional, cause the most severe symptoms of scurvy In animals, these reactions are especially important in wound-healing and in preventing bleeding from capillaries. Ascorbate also acts as an antioxidant, protecting against oxidative stress(2).
The presence of glutathione in cells and extracellular fluids helps maintain ascorbate The biological role of ascorbate is to act as a reducing agent, donating electrons to various enzymatic and a few non-enzymatic reactions.
The one- and two-electron oxidized forms of vitamin C, semidehydroascorbic acid and dehydroascorbic acid, respectively, can be reduced in the body by glutathione and NADPH-dependent enzymatic mechanismsin a reduced state(3).
In humans, vitamin C is essential to a healthy diet as well as being a highly effective antioxidant, acting to lessen oxidative stress; a substrate for ascorbate peroxidase in plants (APX is plant specific enzyme) and an enzyme cofactor for the biosynthesis of many important biochemicals. Vitamin C acts as an electron donor for important enzymes(4).
Ascorbate is required for a range of essential metabolic reactions in all animals. It is made internally by almost all organisms; the main exceptions are most bats, all guinea pigs, capybaras, and the Haplorrhini (one of the two major primate suborders, consisting of tarsiers, monkeys, and humans and other apes). Ascorbate is also not made by many species of birds and fish. All species that do not make ascorbate require it in the diet(5). Vitamin C is found in high concentrations in immune cells, and is consumed quickly during infections. It is not certain how vitamin C interacts with the immune system; it has been hypothesized to modulate the activities of phagocytes, the production of cytokines and lymphocytes, and the number of cell adhesion molecules in monocytes.
It has been claimed that the α-tocopherol form is the most important lipid-soluble antioxidant, and that it protects membranes from oxidation by reacting with lipid radicals produced in the lipid peroxidation chain reaction. This removes the free radical intermediates and prevents the propagation reaction from continuing. This reaction produces oxidised α-tocopheroxyl radicals that can be recycled back to the active reduced form through reduction by other antioxidants, such as ascorbate, retinol or ubiquinol. This is in line with findings showing that α-tocopherol, but not water-soluble antioxidants, efficiently protects glutathione peroxidase 4
(GPX4)-deficient cells from cell death. GPx4 is the only known enzyme that efficiently reduces lipid-hydroperoxides within biological membranes(6).
Thus vitamin E and vitamin C prevent oxidative damage by countering the free radical activity and provide protection against Oxidative stress in CRF.
Based on this the extent of free radical- mediated damage on lipids ( measured as MDA levels) and effect on antioxidant defense mechanism(measured as vitamin C and vitamin E) was studied in CRF patients before dialysis to show the role of antioxidant in preventing the progression of CRF and for monitoring and optimization of antioxidant therapy.
MATeRIAl ANd MeThOd
The blood samples for the present study were collected from Medicine (Nephrology) department, Sri Lakshmi Narayana Institute of Medical Sciences, Pondicherry, The healthy volunteers who come for blood donation served as controls. The cases were 50 CRF patients, age 30-60 years,having inclusion criteria of serum creatinine more than 2mg/dl predialytically.
The exclusion criteria were patients with no clinical or laboratory evidence of diabetes mellitus, liver diseases, lupus nephritis, acute illness, respiratory diseases.
None of the patients had history of antioxidant vitamin supplementation. They were 50 healthy volunteers from blood bank of age 30-60 years of either sex who served as controls.
Informed consent was obtained from each patient before sample collection. The study was approved by Institutional Ethical Committee (IEC) from Sri Lakshmi Narayana Institute of Medical Sciences, From each patient 5 ml blood was collected before dialysis in sterilevacutainer without adding any additives and then centrifuged. The resulting serum was used for studies.
ReSulTS
The level of serum creatinine, Serum urea, MDA, vitamin E and vitamin C are presented in Table 1. The level of serum creatinine, Serum urea and MDA are significantly higher in cases when compared to controls.
The levels of vitamin E and vitamin C are significantly lower in cases as compared to controls.
The correlation between serum creatinine, Serum urea and MDA is represented in Table 2. Serum creatinine and BUN correlates positively with MDA.
Indian Journal of Public Health Research & Development, April-June 2018, Vol.9, No. 2 181 Table 1: Mean ± SD of Biochemical parameters in CRF patients (n = 50) and controls (n = 50) No. Study parametersS. Controls Cases Student t Effect size
(95% CI) P value 1. Serum creatinine
(mg/dl) 0.78±0.16
(0.60-1.40) 8.24±4.34
(2.30-21.60) 10.776 2.37
(1.84-2.98) <0.001 2. Blood Urea
Nitrogen (mg/dl) 12.24±2.61
(6.0-18.0) 86.13±35.25
(28.00-148.00) 13.212 2.91
(2.36-3.66) <0.001 3. MDA (n moles/ml) 0.96±0.22
(0.60-1.50) 2.29±0.48
(1.50-3.66) 16.711 3.70
(2.98-4.62) <0.001 4. Vitamin E (mg/dl) 8.11±1.27
(6.30-11.90) 2.84±0.80
(1.80-4.80) 22.277 4.91
(4.86-5.92) <0.001 5. Vitamin C (mg/dl) 9.85±1.76
(7.40-13.90) 3.70±1.09
(2.00-5.80) 19.372 4.22
(3.46-5.64) <0.001
Table. 2: Pearson correlation of serum creatinine, urea and MdA
Pairs Controls Cases
Pearson correlation P value Pearson correlation P value
MDA Vs Serum creatinine 0.086 0.628 0.209 0.171
MDA Vs Urea 0.236 0.171 0.184 0.292
dISCuSSION
Like several other diseases, chronic renal failure is known to be the result of oxidative stress. There is evidence to show that the oxygen radical scavenger system is impaired in uremic patients.The membrane antioxidant vitamin E (α-tocopherol) is examined as a potential therapeutic intervention that may help to slow the rate of decline of kidney function in such conditions.
An impaired plasma antioxidant defence system is characteristic of chronic renal failure and the uremic state. Vitamin E therapy is also considered as a means of correcting plasma antioxidant status and attenuating the cardiovascular disease that accompanies kidney failure.
Vitamin C(2-3).
ROS causes increased lipid peroxidation. In this study level of MDA in serum of CRF is higher than control. Increased concentration of MDA have been reported in plasma of hemodialyzed patient(7).
Vitamin E is the most potent antioxidant vitamin in the body which prevents lipid peroxidation. Due to an increased level of free radicals in the chronic renal failure, there is an overconsumption of the vitamin E in countering the oxidative damage. The resultant tocopheryl radical formed is converted back to the reduced α - tocopherol by vitamin C. Therefore, the
increased oxidative stress has a two – fold effect: the more and more conversion of vitamin E to vitamin E radical and the subsequent reconversion of oxidized vitamin E to the reduced form by vitamin C. Vitamin E therapy is also considered as means of correcting plasma antioxidant status and attenuating the cardiovascular disease that accompanies kidney failure(8). A study shows the sera of uremic patients has low levels of ascorbic acid (9).Supplementation of Vitamin C alleviates oxidative stress and renal cell injury(10).CRF is associated with impaired endothelium dependent vasodilation and accelerated atherogenesis. ROS modify endothelial function in renal failure and it is found that vitamin C reduces oxidative stress in CRF (2,10-11 ).
There is convincing evidence that diet has a profound effect on the body’s antioxidant status, which depends on the diet’s nutrient composition, absorption, and bioavailability, and which can have antioxidant or prooxidant effects (12). Plants include several antioxidant compounds in natural form as flavonoids, polyphenols, carotenoids, tocopherols, and ascorbic acid. The antioxidants in plant-based foods, in particular fruits and vegetables, may act synergistically in an antioxidant system. Vitamin E is the most important lipophilic antioxidant in the biological system and protects cell membranes from oxidation by the formation of
182 Indian Journal of Public Health Research & Development, April-June 2018, Vol.9, No. 2 reactivity tocopheroxyl radicals(11). Vitamin C is one of
the most important hydrosoluble antioxidants; it exerts its beneficial effects by inhibition of lipid peroxidation and directly scavenges O2 and OH− (1). The lower-than-normal plasma concentration of vitamin C observed in our patients comparing with controls.
Our study showed a significant decrease in the levels of vitamin C as well as vitamin E in the chronic renal failure patients as opposed to the healthy individuals with normal renal function. Vitamin E and vitamin C being the most abundant micronutrient antioxidants in the body which provide protection against free radical damage, their decreased levels could be indicative of oxidative stress.
An increased serum creatinine level is the first indicator of an impaired renal function. People having an increased muscle mass may show slightly elevated creatinine levels. However, in case of chronic renal failure, a gradual and significant increase is observed over a period of time. In the initial stages, there may not be any marked increase in the serum creatinine levels.
But as the GFR declines and reaches below 10 mL/min/1.73 m2, their levels increase rapidly and lead to systemic manifestations.(2) Therefore, even mild elevations of serum creatinine persisting for a longer time are worthy of evaluation for possible decrease in kidney function (5). A high value of serum Urea, most often, indicates a less than normal kidney function.
serum Urea levels may also increase due to other factors like heart failure, dehydration or a diet rich in protein.
Bleeding in the intestines and certain medications may also make the serum Urea higher than normal. However a marked increase in serum Urea along with an increased creatinine level in the serum may be indicative of renal failure (6). The patients included in our study showed significantly elevated levels of serum Urea as well as serum creatinine indicating a greatly impaired renal function (12).
CRF is associated with oxidative stress as evidenced by increase in MDA level with decrease in antioxidant vitamins because of their overconsumption or loss in urine. Further study is needed on a large sample size for better understanding of the concept so that supplementation of antioxidant vitamins may be helpful in preventing oxidative stress and related complication in chronic renal failure patients.
CONCluSION
Our results indicate that even a low intake of antioxidants in the short term has beneficial effects on the antioxidant system as shown by improved levels of vitamins A and C and supplementation of antioxidants can effectively reduce free radicals as oxidative stress in CRF patients. An increased oxidative stress can lead to increased incidences of cardiovascular complications.
Hence, it is important to supplement these patients with the recommended dosage of the vitamins. At present it is untimely to give practical recommendations with regard to antioxidant treatment of patients with renal failure.
Conflict of Interest: Nil
Source of Funding: Self/Diagnostic kits are provided by institution as on complimentary basis for research.
ethical Clearance No.: No.IEC/C-P/042/2016
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