Effects of diabetes mellitus, chronic renal failure and hemodialysis on serum and salivary antioxidant status

Novel impacts of saliva with regard to oral health

The maintenance of balanced oral homeostasis depends on saliva. A readily available and molecularly rich source of biological fluid, saliva fulfills many functions in the oral cavity, including lubrication, pH buffering, and tooth mineralization. Saliva composition and flow can be modulated by different factors, including circadian rhythm, diet, age, drugs, and disease. Recent events have revealed that saliva plays a central role in the dissemination and detection of the SARS-CoV-2 coronavirus. A working knowledge of saliva function and physiology is essential for dental health professionals.

Protective effect of panaxydol against repeated administration of aristolochic acid on renal function and lipid peroxidation products via activating Keap1-Nrf2/ARE pathway in rat kidney

Panaxydol (PX), a polyacetylenic compound isolated from the roots of Panax notoginseng, is found to possess various biological functions. However, its protective effects against aristolochic acid (AA)-induced renal injury have not been elucidated yet. The present study was undertaken to elucidate the renoprotective effect of PX on Wistar male rats via activating Keap1-Nrf2/ARE pathway. Experimental animals were randomized into four groups, such as control group, I/R group, AA (5 mg/kg/d; ip for 10 days), and AA-induced rats treated with PX (10 and 20 mg/kg/d; po for 20 days). At the end of the experimental period, the rats were killed, and the biochemical parameters denoting renal functions were evaluated; histological analysis displaying the renal tissue architecture, real-time quantitative reverse-transcription polymerase chain reaction, and immunohistochemistry (IHC) analysis of Keap1-Nrf2/ARE genes were elucidated. The results demonstrated that the rats administered with AA displayed a significant increase in the blood urea nitrogen level with an increased urine creatinine and protein excretion. Also, the serum levels of urea, uric acid, and albumin levels were increased. Furthermore, the histological evaluation denoted the cellular degeneration with increased tissue lipid peroxidation levels. In contrast, rats administered with PX significantly prevented the tissue degeneration with improved antioxidant levels. Conversely, PX treatment increased the messenger RNA expression of Nrf2, NQO1, HO-1 with an attenuated expression of 4HNE and NOX-4 levels in IHC analysis. Thus, the results of the present study suggest that PX could suppress AA-induced renal failure by suppressing oxidative stress through the activation of Keap1-Nrf2 signaling pathway.

Salivary Redox Biomarkers in Selected Neurodegenerative Diseases

Neurodegenerative diseases (NDDs), such as Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease, are disorders, which cause irreversible and progressive deterioration of the central nervous system. The pathophysiology of NDDs is still not fully explained; nevertheless, oxidative stress is considered as a critical mediator of cerebral degeneration, brain inflammation, as well as neuronal apoptosis. Therefore, it is not surprising that redox biomarkers are increasingly used in the diagnosis of neurodegenerative diseases. As saliva is a very easy to obtain bioliquid, it seems promising to use this biomaterial in the diagnosis of NDDs. Saliva collection is easy, cheap, stress-free, and non-infectious, and it does not require the help of a specialised medical personnel. Additionally, the concentrations of many salivary redox biomarkers correlate with their content in blood serum as well as the degree of disease progression, which makes them non-invasive indicators of NDDs. This paper reviews the latest knowledge concerning the use of salivary redox biomarkers in the diagnosis and prognosis of selected neurodegenerative diseases.

Oxidative Stress in the Pathophysiology of Kidney Disease: Implications for Noninvasive Monitoring and Identification of Biomarkers

Kidney disease represents a serious global health problem. One of the main concerns is its late diagnosis, only feasible in a progressed disease state. The lack of a clinical manifestation in the early stages and the fact that the commonly measured parameters of renal function are markedly reduced only during advanced stages of the disease are the main cause. Changes at the molecular level of the kidney tissue occur even before nitrogenous substances, such as creatinine and urea, start to accumulate in the blood. Renal proximal tubules contain a large number of mitochondria and are critical for the energy-demanding process of reabsorption of water and solutes. Mitochondria are the largest producers of oxygen radicals, which, in turn, increase the susceptibility of kidneys to oxidative stress-induced damage. Free radicals and prooxidants produced during acute or chronic kidney injury may further aggravate the course of the disease and play a role in the pathogenesis of subsequent complications. Prevention might be the solution in CKD, but patients are often reluctant to undergo preventive examinations. Noninvasive markers and the possibility to obtain samples at home might help to increase compliance. This review will provide an overview of the possible uses of markers of oxidative status in noninvasive biofluids in patients with renal disease.

Salivary and Urinary Total Antioxidant Capacity as Biomarkers of Oxidative Stress in Humans

Total Antioxidant Capacity (TAC) is a biomarker often used in order to investigate oxidative stress in many pathological conditions. Saliva and urine can be collected noninvasively and represent attractive diagnostic fluids for detecting biomarkers of various pathological conditions. The reviewed case-control and intervention studies that measured salivary or urinary TAC revealed that diseases, antioxidant foods, or supplements and age, gender, and lifestyle factors influenced salivary or urinary TAC. Salivary and urinary TAC were particularly affected by oral or renal status, respectively, as well as by infection; therefore these factors must be taken into account in both case-control and intervention studies. Furthermore, some considerations on sample collection and normalization strategies could be made. In particular, unstimulated saliva could be the better approach to measure salivary TAC, whereas 24 h or spontaneous urine collection should be chosen on the basis of the study outcome and of the creatinine clearance. Finally, the uric acid-independent TAC could be the better approach to evaluate red-ox status of body, in particular after nutritional interventions and in diseases associated with hyperuricaemia.

Salivary markers of kidney function - Potentials and limitations

Saliva can be collected non-invasively, repeatedly and without trained personnel. It is a promising diagnostic body fluid with clinical use in endocrinology and dentistry. For decades, it is known that saliva contains also urea, creatinine and other markers of renal function. Clinical studies have shown that the salivary concentrations of these markers could be useful for the assessment of kidney function without the need of blood collection. This article summarizes the clinical and experimental data on the use of saliva as a diagnostic fluid in nephrology and points out the advantages, pitfalls, technical requirements and future perspective for the use of saliva as a novel potential diagnostic biofluid.

Salivary antioxidants in patients with type 1 or 2 diabetes and inflammatory periodontal disease: a case-control study

BACKGROUND

The purpose of this study was to evaluate and compare salivary concentrations of reduced, oxidized glutathione, uric acid, ascorbic acid, and total antioxidant capacity in subjects with diabetes and systemically healthy subjects with inflammatory periodontal disease.

METHODS

Sixteen patients with type 1 diabetes mellitus (DM), 25 patients with type 2 DM, and 24 systemically healthy patients, all with inflammatory periodontal disease, were recruited. Whole-saliva samples were obtained, and full-mouth clinical periodontal measurements, including plaque index, probing depth, gingival recession, clinical attachment level, and bleeding on probing, were recorded at six sites per tooth. Saliva flow rate and salivary levels of reduced and oxidized glutathione, vitamin C, uric acid, and total antioxidant capacity were determined. Data were analyzed statistically by non-parametric tests.

RESULTS

The subjects with type 2 DM had fewer teeth and more sites with probing depths >4 mm than the patients with type 1 DM (both P <0.01). The mean salivary reduced-glutathione concentration was lower in patients with type 1 DM than in the other two groups (both P <0.05). No significant differences in the salivary concentrations of the other antioxidants measured were found among the groups (P >0.05). Oxidized glutathione levels in the patients with type 1 DM were significantly lower than in the systemically healthy group (P = 0.007). In both groups with diabetes, salivary reduced-glutathione levels correlated positively with probing depth, and total antioxidant capacity correlated with salivary flow rate (P <0.01).

CONCLUSION

The decrease in salivary reduced-glutathione levels in patients with type 1 DM may have a role in periodontal tissue destruction by predisposing tissues to oxidative stress.

Aucubin prevents loss of hippocampal neurons and regulates antioxidative activity in diabetic encephalopathy rats

In this study, the neuroprotection of aucubin and its mechanism were evaluated in the rat model of diabetic encephalopathy. Diabetes mellitus (DM) rats were stratified by cognitive capability (CC), and assigned to four treatment groups for aucubin treatment (doses of 0, 1, 5 or 10 mg/kg aucubin), with a further two groups of non-DM rats ranked by CC as controls for aucubin (doses of 0 or 5 mg/kg aucubin). Neuroprotection was estimated by the indexes of behavior and histology. Behavioral testing was performed in a Y-maze. The surviving neurons in CA1-CA4 and subiculum (SC) of the hippocampus were counted under a microscope. In addition, the apoptotic neurons in the CA1 of the hippocampus were also examined by using TUNEL staining. In order to clarify the mechanism of aucubin's neuroprotection, the activities of endogenous antioxidants and nitric oxide synthase (NOS) together with the content of lipid peroxide in the hippocampus were assayed. The results proved that aucubin significantly reduced the content of lipid peroxide, regulated the activities of antioxidant enzymatic and decreased the activity of NOS. All these effects indicated that aucubin was a potential neuroprotective agent and its neuroprotective effects were achieved, at least in part, by promoting endogenous antioxidant enzymatic activities.

Use of colorimetric test strips for monitoring the effect of hemodialysis on salivary nitrite and uric acid in patients with end-stage renal disease: a proof of principle

BACKGROUND

Initial screening of potential biomarkers for monitoring dialysis was performed with saliva samples collected from patients with end-stage renal disease (ESRD). A more thorough analysis of the most promising markers identified in the initial screening was conducted with saliva samples acquired at hourly intervals throughout dialysis to monitor analyte concentrations as dialysis progressed. We observed that salivary nitrite (NO(2)(-)) and uric acid (UA) concentrations consistently decreased as dialysis proceeded.

METHODS

Solution-based colorimetric-detection chemistries for NO(2)(-) and UA were converted to a test strip format to produce a simple method for semiquantitatively measuring NO(2)(-) and UA concentrations in the clinic or at the patient's home. We assessed the test strips with saliva samples collected from both ESRD patients undergoing dialysis and healthy control volunteers to qualitatively monitor the effect of dialysis on salivary NO(2)(-) and UA. We used computer software to analyze digital images of the resulting test strip color intensities.

RESULTS

Test strip measurements showed that mean salivary concentrations of NO(2)(-) and UA were decreased in ESRD patients by 86% and 39%, respectively, compared with 15% and 9% for time-matched controls. Comparison of test strip results with calibrated solution-based assays suggests that the test strips can semiquantitatively measure salivary concentrations of NO(2)(-) and UA.

CONCLUSIONS

The colorimetric test strips monitored changes in salivary NO(2)(-) and UA concentrations that occurred in ESRD patients during dialysis. The test strips may prove useful for noninvasively evaluating dialysis progress and may also be useful for monitoring renal disease status.

Direct measurements of xanthine in 2000-fold diluted xanthinuric urine with a nanoporous carbon fiber sensor

High selectivity and sensitivity is reported in the measurements of xanthine in urine by fast scan cyclic voltammetry (FSV) with a nanostructured carbon fiber sensor of 3.5 +/- 0.4 mum radius. Fabrication of the sensors for the measurements is described. Fabrication of the nanostructure at the carbon fiber sensor surface exposes surface pores. SEM images confirm the formation of the nanostructure. The results indicate that the nanostructure improves the sensitivity and limit of detection (LOD) in the measurements of xanthine and uric acid. The sensors allow rapid direct measurements of xanthine in 2000-fold diluted xanthinuric urine and of uric acid in 2000-fold diluted normal urine. The sensitivity and the LOD of xanthine is 0.40 +/- 0.02 nA microM(-1) (0.995) and 1 microM, respectively, and 0.99 +/- 0.01 nA microM(-1) (0.998) and 500 nM for uric acid. The concentration of xanthine in 2000-fold diluted xanthinuric urine is 1.6 +/- 0.2 muM from FSV and from HPLC. The concentration of xanthine and uric acid in urine can be determined by pre- or post-calibration of the sensor in buffer or by the method of standard addition.

Salivary analysis and antioxidants in cleft lip and palate children

OBJECTIVE

To investigate the sialometry, sialochemistry and antioxidants in cleft patients prior to alveolar closure procedures.

DESIGN

Saliva was collected from 21 children with unilateral and bilateral cleft lip and palate (UCLP and BCLP) with overt oronasal alveolar communication and with recurrent licking of fluids and soft diet complaints (the study group) and in 22 normal individuals (the control group). Salivary flow rate was measured, and calcium (Ca), phosphate (P), magnesium (Mg), total protein, albumin, amylase, lactate dehydrogenase (LDH), and secretory IgA were analysed. Salivary total antioxidant status (TAS), peroxidase activity, superoxide dismutase (SOD) activity, uric acid (UA), was also determined.

RESULTS

The sialometry and sialochemistry analyses did not reveal significant difference between the two groups. Salivary median uric acid concentration was 6-fold lower in the cleft group (p<0.05). The median total antioxidant status (TAS) of the cleft group however, was significantly higher by 58% (p<0.005) than that of the control group. Median SOD activity was also higher in the cleft group, by 42%, though these differences did not reach statistical significance.

CONCLUSIONS

Our findings suggest that the oral biology system of cleft patients in their prealveolar closure stage does not differ significantly from normal controls. Low UA found in the saliva of cleft patients may suggest that some genetic alteration of the UA transport occurs simultaneously when cleft lip and palate occur. TAS reduction may also reveal an increased oxidative stress burden in the oral cavities of cleft children which has never been shown before.