Automated measurement of urinary creatinine by multichannel kinetic spectrophotometry

An "on-off-on" Fluorescent Sensor Based on Carbon Dots for the Detection of Au (III) and Creatinine

The present study proposes a new approach for detecting trace amounts of creatinine (Cre) through the utilization of a fluorescence sensor system consisting of nitrogen doped carbon dots (NCDs) and gold ions (Au3+). Yellow fluorescent carbon dots were prepared using a one-step hydrothermal method with o-phenylenediamine and isopropanol as raw materials. First, gold ions are reduced to gold nanoparticles (Au NPs), which bind to NCDs, resulting in electron transfer and fluorescence quenching of NCDs. After adding creatinine, Cre and Au NPs were preferentially combined to form non-fluorescent complexes, and the NCDs fluorescence was restored. The study achieved a detection limit of 1.06 × 10-7 M for Au3+ and 9.29 × 10-9 M for creatinine, indicating a high level of sensitivity. The sensing system has also been successfully utilized for detecting Au3+ in lake water and Cre in human urine, indicating its promising potential and practical applications in the areas of environmental monitoring and biosensing.

Prospective association between phthalate exposure in childhood and liver function in adolescence: the Ewha Birth and Growth Cohort Study

BACKGROUND

Phthalate exposure is ubiquitous due to the widespread use of plastic products in daily life, and affects several health outcomes, including metabolic diseases. In this study, we evaluated the effects of phthalate exposure in childhood on liver function in adolescence.  METHODS: Among 164 Ewha Birth and Growth Cohort Study participants followed up during two exposure periods (when the children were aged 3-5 and 7-9 years), 126 were followed up at age 10-15 years. To investigate the relationship between phthalate exposure during the two periods and liver enzyme levels (ALT, AST, γ-GTP) in adolescence, differences between groups and the dose-response relationship were analyzed. In addition, we investigated differences in liver enzymes between groups based on the combined exposure levels (high or low) during the two periods. The interaction effect between phthalates and BMI on liver enzyme levels was evaluated, stratified by sex.  RESULTS: In the 3-5 year-old exposure period, ALT levels tended to increase as MECPP levels increased, while γ-GTP levels tended to increase as MiBP, MnBP, and ∑DBP levels increased. In addition, the group exposed to consistently high levels of phthalates at both time points had higher liver enzyme levels compared to the group that had lower exposure. In particular, the interaction effect between some phthalate metabolites and BMI in 3-5 year olds affected AST and γ-GTP levels in adolescence only in girls.

CONCLUSIONS

Exposure to phthalates in daily life during childhood affects liver enzyme levels in adolescence. Elevated liver enzyme levels are associated with the development of metabolic syndrome, implying that attention should be paid to phthalate exposure during childhood.

Conventional and nanotechnology based sensors for creatinine (A kidney biomarker) detection: A consolidated review

There is an increasing demand for developing the novel methods for the detection of clinically important metabolites. One among those metabolites is creatinine (2-amino-1-methyl-5H-imidazol-4-one), a waste product, produced by the catabolism of phosphocreatine from muscle and protein metabolism, finally excreted by the kidney. It is very important to measure the creatinine level in human blood and urine because it reflects the muscular and thyroid functions. Importantly, the elevated level of creatinine is considered to be as impairment of the kidney. There are numerous methods existed to measure the concentration of creatinine in blood and urine. In this review, we consolidated the different conventional methods (chromatography, spectroscopy, immune sensor and enzyme-based detections) and their shortcomings. On other hand, we also dissertated the various nanomaterials (chemiluminescence, voltametric, amperometric, conductometric, potentiometric, impedimetric and nano polymer) based creatinine detection methods and their advantages. Finally, we also focussed on the point-of-care detection methods of creatinine determination. This review can conclude the low cost, more efficient and reliable new sensors have been developed with upgraded nanotechnology for the detection of creatinine.

Dual-Purpose Photometric-Conductivity Detector for Simultaneous and Sequential Measurements in Flow Analysis

This work presents a new dual-purpose detector for photometric and conductivity measurements in flow-based analysis. The photometric detector is a paired emitter-detector diode (PEDD) device, whilst the conductivity detection employs a capacitively coupled contactless conductivity detector (C4D). The flow-through detection cell is a rectangular acrylic block (ca. 2 × 2 × 1.5 cm) with cylindrical channels in Z-configuration. For the PEDD detector, the LED light source and detector are installed inside the acrylic block. The two electrodes of the C4D are silver conducting ink painted on the PEEK inlet and outlet tubing of the Z-flow cell. The dual-purpose detector is coupled with a sequential injection analysis (SIA) system for simultaneous detection of the absorbance of the orange dye and conductivity of the dissolved oral rehydration salt powder. The detector was also used for sequential measurements of creatinine and the conductivity of human urine samples. The creatinine analysis is based on colorimetric detection of the Jaffé reaction using the PEDD detector, and the conductivity of the urine, as measured by the C4D detector, is expressed in millisiemens (mS cm-1).

Long-term intake of the reactive metabolite methylglyoxal is not toxic in mice

Reactive carbonyls, including methylglyoxal (MG), are considered toxic compounds in foodstuffs because they irreversibly modify proteins and produce advanced glycation end products (AGEs). Therefore, we studied the long-term effect of increased MG intake in mature adult mice. Six-month-old C57BL/6N mice received MG by drinking water (2.5 mg/ml; i.e., 200-300 mg/kg BW/d) until death. This treatment caused an immediate strong increase in urine MG and a delayed moderate increase in plasma MG. At 24 months of age, mice administered MG showed no changes in the blood and tissue activity of glyoxalase-1 (Glo1), an intracellular MG-detoxifying enzyme; no signs of renal insufficiency and diabetes, including unchanged AGE modifications of plasma and vessel proteins; reduced tumour incidence; and slightly increased survival. Mice simultaneously deficient in the receptor for AGEs (RAGE) and overexpressing Glo1 exhibited higher basal plasma MG levels and did generally not respond to long-term MG intake. In vitro experiments supported the minor relevance of Glo1 in the detoxification of circulating MG but the important role of plasma albumin as an MG scavenger. In conclusion, the detoxification of dietary MG through renal excretion and further mechanisms largely prevents the toxicity of MG and possibly other food-derived reactive carbonyls in mature adults.

Fluorimetric Method for the Determination of Histidine in Random Human Urine Based on Zone Fluidics

In the present study, the determination of histidine (HIS) by an on-line flow method based on the concept of zone fluidics is reported. HIS reacts fast with o-phthalaldehyde at a mildly basic medium (pH 7.5) and in the absence of additional nucleophilic compounds to yield a highly fluorescent derivative (λ_ex/λ_em = 360/440 nm). The flow procedure was optimized and validated, paying special attention to its selectivity and sensitivity. The LOD was 31 nmol·L⁻¹, while the within-day and day-to-day precisions were better than 1.0% and 5.0%, respectively (n = 6). Random urine samples from adult volunteers (n = 7) were successfully analyzed without matrix effect (<1%). Endogenous HIS content ranged between 116 and 1527 μmol·L⁻¹ with percentage recoveries in the range of 87.6%–95.4%.

Quantitative urinalysis using aggregation-induced emission bioprobes for monitoring chronic kidney disease

Early detection and appropriate management of chronic kidney disease can reduce the progression of kidney failure and cardiovascular disease. The urine albumin to creatinine ratio (UACR) test is a standard urine test for identifying individuals at high risk of developing progressive kidney disease. In this study, IDATPE, a novel fluorescent probe with aggregation-induced emission (AIE) features, is successfully developed for creatinine detection and quantitation. An excellent correlation between fluorescent light intensity and creatinine concentration is achieved. In addition, BSPOTPE, a reported excellent AIE bioprobe for human serum albumin (HSA) quantitation, is used together with IDATPE in artificial urine for UACR testing. The mutual interference of HSA and creatinine when the bioprobes are used for quantitation is characterised, with promising results. Further improvements and potential applications in CKD quantitation are highlighted.

Light-emitting diodes for analytical chemistry

Light-emitting diodes (LEDs) are playing increasingly important roles in analytical chemistry, from the final analysis stage to photoreactors for analyte conversion to actual fabrication of and incorporation in microdevices for analytical use. The extremely fast turn-on/off rates of LEDs have made possible simple approaches to fluorescence lifetime measurement. Although they are increasingly being used as detectors, their wavelength selectivity as detectors has rarely been exploited. From their first proposed use for absorbance measurement in 1970, LEDs have been used in analytical chemistry in too many ways to make a comprehensive review possible. Hence, we critically review here the more recent literature on their use in optical detection and measurement systems. Cloudy as our crystal ball may be, we express our views on the future applications of LEDs in analytical chemistry: The horizon will certainly become wider as LEDs in the deep UV with sufficient intensity become available.

Perchlorate, iodine supplements, iodized salt and breast milk iodine content

This study was undertaken to determine if increasing maternal iodine intake through single dose tablets will decrease breast milk concentrations of the iodine-uptake inhibitor, perchlorate, through competitive inhibition. We also sought to determine if the timing of supplementation influences the fraction of iodine excreted in milk versus urine and to compare the effectiveness of iodized salt as a means of providing iodine to breastfed infants. Thirteen women who did not use supplements, seven of whom used iodized salt and six of whom used non-iodized salt, submitted four milk samples and a 24-h urine collection daily for three days. Women repeated the sampling protocol for three more days during which ~150μg of iodine were taken in the evening and again for three days with morning supplementation. Samples were analyzed using isotope-dilution inductively-coupled plasma-mass spectrometry for iodine and isotope-dilution ion chromatography-tandem mass spectrometry for perchlorate. No statistically significant differences were observed in milk iodine or perchlorate concentrations during the two treatment periods. Estimated perchlorate intake was above the U.S. National Academy of Sciences suggested reference dose for most infants. Single daily dose iodine supplementation was not effective in decreasing milk perchlorate concentrations. Users of iodized salt had significantly higher iodine levels in milk than non-users. Iodized salt may be a more effective means of iodine supplementation than tablets.

Prenatal exposure to inflammation induced by zymosan results in activation of intrarenal renin-angiotensin system in adult offspring rats

Prenatal exposure to inflammation produces offspring that are hypertensive in adulthood. The present study was to explore the role of intrarenal renin-angiotensin (Ang) system in the development of hypertension programmed by prenatal exposure to zymosan. Pregnant rats were randomly divided into control group and zymosan group (n = 6). Rats in these two groups were administered intraperitoneally with 0.5 ml vehicle and 2.37 mg/kg zymosan, respectively, on the eighth, tenth, and 12th day during gestation. The results showed the glomerular number and creatinine clearance rate decreased significantly in offspring of zymosan-treated rats. The renal cortex renin mRNA expression, Ang II-positive cells in renal cortex, and Ang II expression in renal medulla increased significantly in offspring of zymosan-treated rats at 7, 16, and 25 weeks of age. The plasma renin activity and Ang II concentration were unchanged. In conclusion, prenatal exposure to zymosan resulted in the activation of intrarenal renin-Ang system in adult offspring rats.

Controlled band dispersion for quantitative binding determination and analysis with electrospray ionization-mass spectrometry

This review discusses recent emerging techniques that have been used to couple flow-injection analysis (FIA) and electrospray ionization-mass spectrometry (ESI-MS) for the quantitation of noncovalent binding interactions. Focus is placed predominantly on two such methods. Diffusion-based measurements, developed by Konermann and co-workers, uses controlled-band dispersion prior to ESI-MS to determine diffusion constants and binding constants based on the temporal variation of ligand signal measured in the mass spectrum (an indirect technique). Dynamic titration, developed by Schug and co-workers, is a direct method, where a temporal compositional gradient of a guest molecule is induced in the presence of host in solution to monitor the concentration dependence of complex formation as a function of observed complex ion abundance after ESI-MS. Further discussion places these techniques in the context of a variety of other direct and indirect ESI-MS-based binding determination methods, and highlights advantages, disadvantages, and practical considerations for their proper use to investigate a broad range of macromolecular and small-molecule interaction systems.

Acute renal failure enhances the antidotal activity of pralidoxime towards paraoxon-induced respiratory toxicity

We recently showed in a rat model of dichromate-induced acute renal failure (ARF) that the elimination but not the distribution of pralidoxime was altered resulting in sustained plasma pralidoxime concentrations. The aim of this study was to compare the efficiency of pralidoxime in normal and acute renal failure rats against paraoxon-induced respiratory toxicity. Ventilation at rest was assessed using whole-body plethysmography after subcutaneous administration of either saline or paraoxon (50% of the LD(50)), in the control and ARF rats. Thirty minutes after administration of paraoxon, either saline or 50mg/kg of pralidoxime was administered intramuscularly. ARF had no significant effects on the ventilation at rest. The effects of paraoxon on respiration were not significantly different in the control and ARF group. Paraoxon increased the total time (T(TOT)), expiratory time (T(E)) and tidal volume (V(T)), and decreased the respiratory frequency (f). In paraoxon-poisoned rats with normal renal function, pralidoxime had a significant but transient effect regarding the T(TOT) and V(T) (p<0.05). In the ARF group, the same dose of pralidoxime significantly decreased the T(TOT), T(E), and V(T) and increased f during 90 min (p<0.01). In conclusion, pralidoxime had partial and transient effects towards paraoxon-induced respiratory toxicity in control rats; and a complete and sustained correction in ARF rats.