Oxalate homeostasis.

Oxalate homeostasis is maintained through a delicate balance between endogenous sources, exogenous supply and excretion from the body. Novel studies have shed light on the essential roles of metabolic pathways, the microbiome, epithelial oxalate transporters, and adequate oxalate excretion to maintain oxalate homeostasis. In patients with primary or secondary hyperoxaluria, nephrolithiasis, acute or chronic oxalate nephropathy, or chronic kidney disease irrespective of aetiology, one or more of these elements are disrupted. The consequent impairment in oxalate homeostasis can trigger localized and systemic inflammation, progressive kidney disease and cardiovascular complications, including sudden cardiac death. Although kidney replacement therapy is the standard method for controlling elevated plasma oxalate concentrations in patients with kidney failure requiring dialysis, more research is needed to define effective elimination strategies at earlier stages of kidney disease. Beyond well-known interventions (such as dietary modifications), novel therapeutics (such as small interfering RNA gene silencers, recombinant oxalate-degrading enzymes and oxalate-degrading bacterial strains) hold promise to improve the outlook of patients with oxalate-related diseases. In addition, experimental evidence suggests that anti-inflammatory medications might represent another approach to mitigating or resolving oxalate-induced conditions.

Oxalate Balance in Peritoneal Dialysis Patients: A Potential Role of Dialysis-related Peritonitis.

BACKGROUND: Little evidence is available on oxalate balance in peritoneal dialysis (PD) patients. PATIENTS AND METHODS: We performed a cross-sectional observational pilot study with 62 adult PD patients to document oxalate balance and explore its association with PD-related peritonitis. Plasma oxalate concentration, levels of oxalate excretion in 24-h urine, and peritoneal dialysis effluent were evaluated. The peritoneal oxalate transport status and renal and peritoneal oxalate clearances were calculated according to the PD-related peritonitis history. RESULTS: PD patients with a history of peritonitis had a statistically significantly lower peritoneal oxalate clearance, daily peritoneal oxalate excretion, and overall oxalate removal rate compared with the peritonitis-free PD patients. They had a 4-fold risk of plasma oxalic acid increase, and even a single episode of dialysis-related peritonitis resulted in plasma oxalate elevation. CONCLUSION: Peritoneal oxalate clearance plays an important role in oxalate balance in PD patients and, therefore, dialysis-related peritonitis is a significant predictor for hyperoxalemia. Further well-designed clinical trials need to be undertaken before the association between peritonitis and oxalate balance in PD patients is more clearly understood.

Portulaca Oleracea-associated oxalate nephropathy complicated with an ANCA-positive acute renal injury: A case report.

Oxalate nephropathy is a rare disease that can lead to acute kidney injury (AKI). In clinical practice, as renal biopsy is required for diagnosis, physicians often do not have sufficient understanding of this disease. When AKI is associated with positive blood anti-neutrophil cytoplasmic antibodies (ANCA), a diagnosis of renal injury due to ANCA-associated vasculitis is likely to be made, leading to treatment with immunosuppressive therapy. A case of AKI after eating a large quantity of Portulaca oleracea is reported. While blood P-ANCA was positive, both urine proteinuria and urine occult blood were negative. Renal biopsy was performed and identified an acute tubulointerstitial injury: disc-shaped crystals were seen in the lumen of renal tubules that demonstrated birefringence under polarized light, and an oxalate nephropathy was therefore diagnosed. Typical histological changes of an ANCA-associated vasculitis with renal injury such as cellulose-like necrosis and crescent formation were not present. After the patient stopped eating P. oleracea, and following rehydration and hemodialysis, renal function returned to normal. In patients with AKI, the secondary causes of hyperoxalemia should be sought and attention paid to excluding an oxalate nephropathy. In patients with AKI who are ANCA-positive, it is prudent to complete the renal pathological diagnostic process before assuming that the renal injury is caused by an ANCA-associated vasculitis, and before starting hormone and immunosuppressive therapy.

Redox Responsive Copolyoxalate Smart Polymers for Inflammation and Other Aging-Associated Diseases.

Polyoxalate (POx) and copolyoxalate (CPOx) smart polymers are topics of interest the field of inflammation. This is due to their drug delivery ability and their potential to target reactive oxygen species (ROS) and to accommodate small molecules such as curcumin, vanilline, and p-Hydroxybenzyl alcohol. Their biocompatibility, ultra-size tunable characteristics and bioimaging features are remarkable. In this review we discuss the genesis and concept of oxylate smart polymer-based particles and a few innovative systemic delivery methods that is designed to counteract the inflammation and other aging-associated diseases (AADs). First, we introduce the ROS and its role in human physiology. Second, we discuss the polymers and methods of incorporating small molecule in oxalate backbone and its drug delivery application. Finally, we revealed some novel proof of concepts which were proven effective in disease models and discussed the challenges of oxylate polymers.

A randomized clinical trial on the efficacy of a new oxalate-containing sensitivity relief strip following professional vs self-application.

OBJECTIVES: The purpose of this study was to determine the efficacy of 3.14% dipotassium oxalate monohydrate-containing strip on the relief of dentinal hypersensitivity (DH). A second objective was to determine whether there was a difference in DH levels when the strip was self-applied vs applied by a dental professional. METHODS: Sixty subjects were randomized into self-applied, professionally applied or placebo-strip groups. Dentinal hypersensitivity was evaluated by a blinded examiner, using the Schiff Air Scale (SAS). A verbal rating scale (VRS) was also used to measure the subjects' perception of pain. Measures were taken at baseline, 30 minutes, 4 and 8 weeks post-treatment. RESULTS: There was a significant reduction in DH in all three groups (P ≤ .05) at 30 minutes and 8 weeks post-treatment. At the 4-week follow-up, only the self- and professionally applied (active ingredient) groups had a significant reduction in DH compared to baseline. When comparing the reduction in DH levels between groups, the only significant difference occurred between the professionally applied treatment group and the placebo group at the 4-week follow-up. There were no significant differences in DH reduction levels achieved between the self- and professionally applied groups (P > .05). CONCLUSIONS: This study confirmed the short-term (4 weeks) effectiveness of a single application of 3.14% dipotassium oxalate monohydrate-containing strip. Self- and professional application were not shown to be different.

Effect of theobromine-containing toothpaste on dentin tubule occlusion in situ.

OBJECTIVES: Dentin hypersensitivity (DH) is treated by either occlusion of dentin tubules or nerve desensitization. This in situ study compared dentin tubules occlusion by theobromine-containing dentifrices with (Theodent-classic-F®, TCF) and without (Theodent-classic®, TC) fluoride with 1,500 ppm fluoride toothpaste, Colgate®-Regular (Fluoride) and Novamin®-containing toothpaste, Sensodyne®-5000-Nupro (Novamin®). METHODS: Each subject wore four intraoral appliances bearing dentin blocks while using one of four test dentifrices (n = 20/dentifrice) twice daily for 7 days. The four appliances were removed successively after 1, 2, 3, and 7 days. Treated blocks and their control (untreated) blocks were examined with scanning electron microscopy (SEM). Effects were compared statistically (ANOVA/Tukey's) based on percentage of surface area covered by deposited precipitate layer (%DPL) and percentage of fully open (%FOT), partially occluded (%POT), and completely occluded (%COT) tubules in each block calculated relative to the number of tubules in their control blocks. RESULTS: SEM observation indicated an increased %COT and %DPL over time. After 1 and 2 days, %COT was comparable with TC and TCF, and significantly (p < 0.05) higher compared with Novamin® and Fluoride. Following 3 and 7 days, %COT was comparable among TC, TCF, and Novamin®, but remained significantly lower in Fluoride. At any time, %DPL was significantly (p < 0.05) higher in TC, TCF, and Novamin® compared with Fluoride. CONCLUSIONS: Theobromine-containing toothpastes with and without fluoride have equal potential in occluding dentin tubules within a shorter time period than Novamin®-containing toothpaste; however, the three demonstrated equal potential after 1 week, but not the fluoride toothpaste. CLINICAL RELEVANCE: Theobromine-containing toothpaste promoted dentin tubule occlusion thus shows potential to relief DH.

Zolmitriptan oxalate and zolmitriptan camphorsulfonate: the first structural study of salt complexes of the antimigraine drug zolmitriptan.

Zolmitriptan hydrogen oxalate [(S)-dimethyl(2-{5-[(2-oxo-1,3-oxazolidin-4-yl)methyl]-1H-indol-3-yl}ethyl)azanium hydrogen oxalate], C16H22N3O2(+)·C2HO4(-), (I), and zolmitriptan camphorsulfonate [(S)-dimethyl(2-{5-[(2-oxo-1,3-oxazolidin-4-yl)methyl]-1H-indol-3-yl}ethyl)azanium (S,R)-{2-hydroxy-7,7-dimethylbicyclo[2.2.1]heptan-1-yl}methanesulfonate], C16H22N3O2(+)·C10H15O4S(-), (II), are the first reported salt complexes of the antimigraine drug zolmitriptan. Compound (I) crystallizes in the space group P2(1) with two molecules of protonated zolmitriptan and two oxalate monoanions in the asymmetric unit, while compound (II) crystallizes in the space group P2(1)2(1)2(1) with one protonated zolmitriptan molecule and one camphorsulfonate anion in the asymmetric unit. The orientations of the ethylamine side chain and the oxazolidinone ring with respect to the indole ring of the zolmitriptan cation are different for (I) and (II). In (I), they are oriented in opposite directions and the molecule adopts a step-like appearance, while in (II) the corresponding side chains are folded in the same direction, giving the molecule a cup-like appearance. The zolmitriptan molecules of (I) form an R2(2)(8) dimer, while in (II) they form a helical chain with a C(11) motif. The oxalate monoanions of (I) interact with the zolmitriptan cations and extend the dimer into a three-dimensional hydrogen-bonded network. In (II), the camphorsulfonate anion forms an R2(2)(15) ring motif with the zolmitriptan cation.

Clinical performance of cervical restorations with desensitizing agents: 18-month clinical trial.

PURPOSE: To evaluate the clinical performance and postoperative sensitivity of noncarious Class V restorations with and without the use of a potassium oxalate-based desensitizing agent over a period of 18 months. MATERIALS AND METHODS: One hundred forty cervical lesions (40 patients) were selected and randomly divided into four groups: group 1 (G1) - teeth restored with the application of a potassium oxalate-based desensitizing agent (BisBlock) after acid etching and before the application of the adhesive Adper Single Bond 2; group 2 (G2) - teeth restored using the same adhesive system used in G1, without the use of any desensitizing agent; group 3 (G3) - similar to G1, but using the adhesive One-Step; group 4 (G4) - similar to G3, but without the application of BisBlock. All restorations were evaluated (double blind) after 1 week and 2, 6, 12, and 18 months according to the modified USPHS criteria. The McNemar and chi-square tests were used to analyze the results (p ≤ 0.05). RESULTS: There were no statistical differences between groups restored with or without the use of a desensitizing agent for postoperative sensitvity. After 18 months, retention rates proved to be statistically significantly lower for One-Step than Adper Single Bond 2. CONCLUSION: The use of potassium oxalate-based desensitizing agent did not decrease postoperative sensitivity when it was used under composite resin restorations.

Tubular occlusion of simulated hypersensitive dentin by the combined use of ozone and desensitizing agents.

OBJECTIVE: Ozone was suggested for treatment of hypersensitive dentin. The purpose of this study was to investigate the effect of ozone, with or without the use of desensitizing agents, on patency and occlusion of simulated hypersensitive dentin. MATERIALS AND METHODS: Sixty standardized dentin slabs were randomly divided into six groups: distilled water (Control), ozone treatment, fluoride desensitizer (ALLSolutions, Dentsply), oxalate desensitizer (D/Sense Crystal, Centrix), combined use of ozone/fluoride and combined use of ozone/oxalate. Ozone gas was delivered from OzonyTronX (Mymed). Specimens were evaluated using a scanning electron microscope and digital image analysis before and after treatment. RESULTS: Statistical analysis using ANOVA and Mann-Whitney U-tests revealed significantly lower percentage of tubular occlusion with ozone treatment than distilled water at p ≤ 0.05. Scanning electron microscope photomicrographs of oxalate desensitizer specimens revealed a thick homogenous precipitate with significantly higher percentage of tubular occlusion than fluoride desensitizer and distilled water. Combined use of ozone/fluoride resulted in a significantly higher percentage of tubular occlusion than fluoride desensitizer alone. However, no significant difference was found between oxalate desensitizer and combined use of ozone/oxalate. CONCLUSIONS: The use of ozone gas is a viable adjunct to fluoride-containing desensitizers in enhancing tubular occlusion, but is not effective with oxalate desensitizers.

Dentin hypersensitivity and oxalates: a systematic review.

Treatment of dentin hypersensitivity with oxalates is common, but oxalate efficacy remains unclear. Our objective was to systematically review clinical trials reporting an oxalate treatment compared with no treatment or placebo with a dentin hypersensitivity outcome. Risk-of-bias assessment and data extraction were performed independently by two reviewers. Standardized mean differences (SMD) were estimated by random-effects meta-analysis. Of 677 unique citations, 12 studies with high risk-of-bias were included. The summary SMD for 3% monohydrogen-monopotassium oxalate (n = 8 studies) was -0.71 [95% Confidence Interval: -1.48, 0.06]. Other treatments, including 30% dipotassium oxalate (n = 1), 30% dipotassium oxalate plus 3% monohydrogen monopotassium oxalate (n = 3), 6% monohydrogen monopotassium oxalate (n = 1), 6.8% ferric oxalate (n = 1), and oxalate-containing resin (n = 1), also were not statistically significantly different from placebo treatments. With the possible exception of 3% monohydrogen monopotassium oxalate, available evidence currently does not support the recommendation of dentin hypersensitivity treatment with oxalates.

The efficacy of three desensitizing agents used to treat dentin hypersensitivity.

BACKGROUND: In a single-center, double-masked, split-mouth-designed, clinical short-term trial, the authors assessed the clinical responses of teeth with dentin hypersensitivity (DH) after treating the teeth with one of three desensitizing agents across four weeks. METHODS: The authors selected 131 teeth with DH in 11 participants. The authors assessed DH of the teeth by using tactile stimuli and air stimuli and had the participants record the level of sensitivity by means of a visual analog scale (VAS). The authors then treated the teeth with one of three desensitizing agents (Pain-Free [Parkell, Edgewood, N.Y.], BisBlock [Bisco, Schaumburg, Ill.], Seal & Protect [Dentsply DeTrey, Konstanz, Germany]) that they applied according to the manufacturers' instructions. The authors used a split-mouth-designed study in which the teeth in different quadrants of the participants' mouths received different desensitizing agents. The authors also conducted DH evaluations at 10 minutes after treatment and at one, two, three and four weeks. The authors analyzed data statistically by using Mann-Whitney U and Kruskal-Wallis tests. RESULTS: The results of the statistical analysis showed that all VAS scores at the posttreatment evaluation periods were reduced significantly compared with those at baseline (P<.05). More teeth were sensitive to air stimuli than to tactile stimuli. The mean VAS scores for DH in the mandibular teeth were significantly higher than for those in maxillary teeth immediately after treatment (for tactile stimuli) and two weeks after the first application (for air stimuli) (P<.05) CONCLUSIONS: All three desensitizing agents were effective in relieving DH up to four weeks, independent of their application procedures. There was, however, a significant reduction in mean sensitivity scores of teeth that had been treated with Seal & Protect and Pain-Free compared with those of BisBlock at weeks two, three and four. CLINICAL IMPLICATIONS: The study results should be considered with caution, as it is not clear how many of the pain relief effects were related to the natural desensitization of teeth over time.

Clinical evaluation of a 3% potassium oxalate gel and a GaAlAs laser for the treatment of dentinal hypersensitivity.

OBJECTIVES: This study evaluated the immediate and 3 month clinical effects of a low-level gallium-aluminum-arsenide (GaAlAs) laser and a 3% potassium oxalate gel for the treatment of dentinal hypersensitivity. MATERIALS AND METHODS: A total of 164 teeth from 30 patients with clinical diagnoses of dentinal hypersensitivity were selected for this randomized, placebo-controlled, double-blind clinical study. The teeth were randomized to three groups: GaAlAs laser, oxalate gel, and placebo gel. The treatment sessions were performed at 7 d intervals for four consecutive weeks. The degree of sensitivity in response to an air blast and tactile stimuli was assessed according to a visual analogue scale at baseline, immediately after the fourth application, and then 3 months after the fourth application. The reductions in dentinal hypersensitivity from baseline at the two follow-up assessments were evaluated as the main outcome. RESULTS: In both the active and control groups, there were statistically significant reductions in dentinal hypersensitivity immediately after and 3 months after the treatments, when compared with the hypersensitivity at baseline. No significant differences among the three groups could be detected in their efficacy at either the immediate or 3 month evaluations irrespective of the stimulus. CONCLUSIONS: The treatments under study were effective for reducing dentinal hypersensitivity, and longer observational periods could enhance the ability of studies to detect differences between active and placebo groups.

Calcium silicate coating derived from Portland cement as treatment for hypersensitive dentine.

OBJECTIVES: To evaluate the in vitro effectiveness on dentine permeability and dentine morphology of a calcium silicate treatment based on Portland cement (DSC). METHODS: The experimental treatment consisted of a calcium silicate paste based on Portland cement that was applied on dentine surface for 3 min. A professional re-mineralizing treatment (GC Tooth Mousse), two in office desensitizing agents (D/Sense Crystal, and By Sealant) and a commercial toothpaste Dentosan S were studied as comparison materials. All materials were applied accordingly with manufacturer directions on wet dentine. The quantitative changes in the hydraulic conductance i.e., permeability through tubules of dentine discs samples produced by treatment were quantified in vitro using a hydrostatic device working at 6.9 kPa. SEM/EDX analyses of dentine were carried out to obtain qualitative information on dentine morphology and surface deposits and to study their relationship with the hydraulic conductance. After treatment, each dentine sample was immersed in artificial saliva and permeability re-evaluated. Finally, each sample was exposed to 0.02 M citric acid solution and the final permeability was assessed. RESULTS: The experimental treatment and both oxalate-based products (D/Sense Crystal and By Sealant) significantly decreased dentine permeability and created crystals and precipitates on the dentine surface that reduced the diameter of dentinal tubules. Artificial saliva immersion and citric acid challenge increased dentine permeability and partially modified the treated surfaces. Dentosan S and GC Tooth Mousse treatments partially reduced dentine permeability and created small amount of precipitates that were removed by saliva immersion and citric acid exposure. EDX revealed the presence of calcium-rich layer after DSC experimental treatment. CONCLUSIONS: The application of the experimental calcium silicate paste and oxalate-based treatments was determined to be effective on dentine permeability reduction and tubules occlusion. The clinical use as desensitizing agent of materials derived from Portland cement as desensitizing agent should be considered for dentine hypersensitivity treatment.

The influence of soft acidic drinks in exposing dentinal tubules after non-surgical periodontal treatment: a SEM investigation on the protective effects of oxalate-containing phytocomplex.

OBJECTIVE: The aim of this study was to investigate the different smear layer morphologies produced by instrumentation with a hand curette and a periodontal sonic scaler for potential removal by soft acidic solution. The effect of a new oxalate-containing phytocomplex spray in preventing tubules exposure after citric acid solution application was also evaluated. METHODS: Thirty recently extracted human teeth were used to obtain root dentinal fragments and divided in two groups: Curette treatment (CRT) root planed applying 30 working strokes to each surface using a Gracey's curette 5-6 and Ultrasonic scaler (USC) treated using a periodontal scaler mounted on an ultrasonic hand-piece for 30 seconds. Each principal group was further divided in three sub-groups (Control, Acid challenge and Acid/Phyto-oxalate). The control group samples were immersed in distilled water buffered to pH 7.4 using NH4OH solution. The samples of the acid challenge group were immersed in a solution of citric acid 0,02 M; [pH 2.5] for 3 minutes. The samples of the Acid/Phyto-oxalate group were sprayed for 15 sec with a 1.5% phytocomplex spray prior to immersion. Samples were examined using SEM. RESULTS: Ultrasonic instrumentation created a very thin smear layer whereas curettes produced a multilayered smear layer. The acidic solution was able to remove the smear layer from root surfaces treated with ultrasonic instrumentation exposing the dentinal tubules. The smear layer on the root surfaces treated with hand instruments was not completely removed. The phytocomplex solution was able to prevent dentinal tubule exposure. CONCLUSIONS: Acidic soft drinks are able to remove the smear layer created on root surfaces during different non-surgical periodontally treatments. The smear plugs created by hand instrumentation appeared to be more resistant to acid attack. The tested phytocomplex solution protected the dentine from demineralization and it might prevent post-treatment dentinal hypersensitivity induced by acidic soft drinks.

Effects of precementation desensitizing laser treatment and conventional desensitizing agents on crown retention.

This study aimed to compare the effect of precementation desensitizing laser treatment and conventional desensitizing agents on crown retention. Crowns were fabricated for 50 molar teeth, and specimens were assigned to 5 groups based on treatment method: untreated control group (CON), laser group (LAS), sodium fluoride group (FLU), Oxagel oxalate group (OXA), and Gluma primer group (GLU). All crowns were luted with glass-ionomer cement. Tensile force was applied for crown dislodgement. Recorded forces and calculated retentive strengths were as follows: CON (261 N) > LAS (223 N) = FLU (208 N) > GLU (161 N) = OXA (147 N) (P < .05). The differences in force magnitudes between all groups were significant (P < .05), except for LAS versus FLU and GLU versus OXA. The retention decrease was 15% for LAS, 20% for FLU, 38% for GLU, and 44% for OXA. Laser treatment had a less negative effect on retention for crowns luted with glass-ionomer cement than the other treatment modalities, and it may be a more suitable desensitization method if crown retention can be moderately sacrificed.

Microtensile bond strengths of composite to dentin treated with desensitizer products.

PURPOSE: This study was designed to analyze the influence of desensitizing procedures on dentin bond strength. MATERIALS AND METHODS: Forty bovine incisors were used, divided into four groups (n = 10): G1: control; G2: Gluma Desensitizer (Heraeus Kulzer); G3: Oxa-Gel (Art-Dent); G4: low-intensity laser (MMOptics). The buccal surface was wet ground flat with 180-, 400- and 600-grit silicon carbide abrasive paper to expose midcoronal dentin and create a uniform surface. After the application of the desensitizing agents to the exposed dentin, the specimens were etched with 35% phosphoric acid for 30 s, and an adhesive (Single Bond) was applied and light cured. A 4-mm high crown of composite resin (Filtek Z250) was then built up. Specimens were trimmed to an hourglass shape with cross sections of 1 mm2. Each specimen was individually fractured by a microtensile testing machine at a crosshead speed of 0.5 mm/min. The data, recorded in MPa, were analyzed with one-way ANOVA and the Duncan test (p = 0.05). RESULTS: Specimens treated with dentin desensitizers (except Gluma) yielded significantly lower mean bond strengths than nontreated control specimens. The mean values in MPa (+/- SD) were: G1: 13.4 (6.2); G2: 13.2 (4.8); G3: 7.15 (4.3); G4: 7.21 (4.6). CONCLUSIONS: Among the desensitizing agents studied, only Gluma Desensitizer did not detrimentally influence the bond strength values. It is a useful material for dentin desensitization.

Effects of pre- or post-application of calcium chloride on occluding ability of potassium oxalate for the treatment of dentin hypersensitivity.

PURPOSE: To evaluate whether calcium ion supply using 1-6 mol/L CaCl2 solution could enhance the occluding ability of dentin tubules with 30% potassium oxalate treatment. METHODS: Calcium chloride solution (1-6 mol/L) was applied to dentin disks before or after application of 30% potassium oxalate solution. Occluding ability after potassium oxalate treatment was evaluated with scanning electron microscopic (SEM) observation and measurement of dentin permeability. In addition, the composition of the precipitate formed when mixing potassium oxalate and calcium chloride was analyzed with a powder x-ray diffractometer (XRD). RESULTS: SEM observations revealed that the dentin tubules were occluded homogeneously and completely with the precipitate when calcium chloride solution was applied before or after potassium oxalate treatment. However, the depth of the precipitate in dentin tubules from the dentin surface became shallower when pre-treated with calcium chloride before potassium oxalate. Although dentin permeability was greatly reduced in both groups, no significant difference could be observed between samples with and without calcium chloride application.