Factors influencing the assay of creatinine

Physiological Alterations of Subchronic Lead Exposure Induced Degeneration of Epithelial Cells in Proximal Tubules and the Remedial Effect of Curcumin-III in Meriones shawi: a Possible Link with Vasopressin Release

At the industrial working conditions, lead exposure could induce several alterations for the human body. Subchronic lead exposure is linked with several injuries including cerebral and renal dysfunctions. The present work discusses the effects of subchronic lead toxicity (3 g/l) in drinking water during the period of treatment (6 weeks) on vasopressin system and epithelial cells in proximal tubules. Also, we aimed to evaluate the protective effect of curcumin-III administered orally by gavage (30 mg/kg BW), against subchronic Pb exposure in Meriones shawi. The biochemical and histopathological examinations demonstrate renal damages induced by lead toxicity. In addition, the behavioral and immunohistochemical studies revealed that Pb neurotoxicity exhibited an anxious behavior with a significant elevation of the vasopressin (AVP) staining within the paraventricular nuclei. The study showed also curcumin-III restored the renal alterations with an anxiolytic effect. Moreover, it restored the AVP level in the studying nuclei. Our work supports a possible link between AVP release and epithelial degeneration in the proximal tubules, and shows a new pharmacological effect of curcumin-III as an anxiolytic agent against lead toxicity.

OUP accepted manuscript

Objectives

To describe the therapeutic drug monitoring (TDM) of cefepime in non-critically ill adults and compare four different ways of dosing: conventional table-based; empirically adjusted following TDM; individualized based on a population pharmacokinetic (PopPK) model without TDM; and TDM-adjusted with a Bayesian approach integrating TDM and PopPK.

Methods

We conducted a retrospective study in a tertiary centre to examine the current practice of TDM and to evaluate the potential for improvement by PopPK-based software individualization. The prediction of trough concentrations and the total daily doses (TDD) prescribed according to each approach were compared by calculating the mean logarithmic bias and the root mean squared error, complemented by linear regression and variance analysis.

Results

Among 168 trough concentrations in 119 patients (median: 12 mg/L), 38.6% of measurements exceeded 15 mg/L, the reported threshold for neurotoxicity. Nine patients developed neurotoxicity. The prediction performance of PopPK alone for trough concentrations was moderate, but clearly improved after integration of TDM. Accordingly, TDD were significantly lower for a priori PopPK-based dosage (mean: 2907 mg/24 h) compared with actual table-based dosage (4625 mg/24 h, P < 0.001). They were also lower for a posteriori dosage based on PopPK and TDM (3377 mg/24 h) compared with actual dosage after empirical TDM (4233 mg/24 h, P < 0.001), as model-based adjustment privileged more frequent administrations.

Conclusions

Our observations support routine TDM of cefepime to prevent overdosing and subsequent toxicity in the non-critically ill. Software-based individualization seems promising to optimize the benefits of TDM, but has little potential to replace it.

The Glomerular Filtration Rate: From the Diagnosis of Kidney Function to a Public Health Tool

The prevalence of chronic kidney disease (CKD) continues to increase worldwide, as well as the associated morbidity and mortality and the consequences on the patients' quality of life and countries' economies. CKD often evolves without being recognized by patients and physicians, although the diagnosis is based on two simple laboratory data: the estimated glomerular filtration rate (eGFR) and urine analysis. To measure GFR, the knowledge about the physiologic processes at the nephron level, the concept of clearance, and the identification of creatinine as a suitable endogenous marker for measuring the creatinine clearance (CrCl) had to be previously developed. On those bases, different equations to calculate CrCl (Cockcroft and Gault, 1976), or estimated GFR (four variables MDRD, 1999; CKD-Epi, 2009, among others) were generated. They all include creatinine and some demographic data, such as sex and age. However, to compare results throughout life or among laboratories, the creatinine determination must be standardized. In addition, the accuracy of these equations remains controversial in certain subgroups of patients. For these reasons, other mathematical models to improve CrCl estimation have been developed, such as when urine cannot be collected, in debilitated elderly patients and patients with trauma, diabetes, or obesity. Currently, eGFR in adults can be measured and reported immediately, using isotope dilution mass spectrometry traceable creatinine-based equations. In conclusion, based on knowledge obtained from renal physiology, eGFR can be used in the clinic for the diagnosis and early treatment of CKD, as well as a public instrument to estimate the prevalence.

The Transcription Factor Sox6 Controls Renin Expression during Renal Artery Stenosis

Background

Renal artery stenosis (RAStenosis) or renal artery occlusion is an intractable problem affecting about 6% of people >65 and up to 40% of people with coronary or peripheral vascular disease in the Unites States. The renal renin-angiotensin-aldosterone system plays a key role in RAStenosis, with renin (which is mainly produced in the kidney) being recognized as the driver of the disease. In this study, we will determine a new function for the transcription factor Sox6 in the control of renal renin during RAStenosis.

Methods

We hypothesize that knocking out Sox6 in Ren1d-positive cells will protect mice against renovascular hypertension and kidney injury. To test our hypothesis, we used a new transgenic mouse model, Ren1dcre/Sox6fl/fl (Sox6 KO), in which Sox6 is knocked out in renin-expressing cells. We used a modified two-kidney, one-clip (2K1C) Goldblatt mouse model to induce RAStenosis and renovascular hypertension. BP was measured using the tail-cuff method. Renin, prorenin, Sox6, and NGAL expressions levels were measured with Western blot, in situ hybridization, and immunohistochemistry. Creatinine levels were measured using the colorimetric assay.

Results

Systolic BP was significantly lower in Sox6 KO 2 weeks after RAStenosis compared with Sox6 WT (Ren1dcre/Sox6wt/wt). Renin, prorenin, and NGAL expression levels in the stenosed kidney were lower in Sox6 KO compared with Sox6 WT mice. Furthermore, creatinine clearance was preserved in Sox6 KO compared with Sox6 WT mice.

Conclusions

Our data indicate that Sox6 controls renal renin and prorenin expression and, as such, has a function in renovascular hypertension induced by RAStenosis. These results point to a novel transcriptional regulatory network controlled by Sox6.

Lead (Pb) exposure induces physiological alterations in the serotoninergic and vasopressin systems causing anxiogenic-like behavior in Meriones shawi: Assessment of BDMC as a neuroprotective compound for Pb-neurotoxicity and kidney damages

BACKGROUND

Studies have shown that lead (Pb) is one of hazardous heavy metals with various adverse effects on human health including mental health; Pb can induce psychiatric disorders like anxiety. In the present work, we examined the potential of bisdemethoxycurcumin (BDMC) as a neuroprotective agent against lead induced anxiety inMeriones shawi (M. shawi).

METHODS

We asses, the potential of three consecutive day exposure to Pb (25 mg/kg body weight) in inducing anxiogenic effect, serotoninergic and vasopressinergic disruptions inM. shawi. This was done using neurobehavioral tests (open field, elevated plus maze), immunohistochemestry by anti-serotonin (5-HT), and anti-vasopressin (AVP) antibodies. We also measured the possible restorative potential of BDMC (30 mg/kg body weight), delivered by oral gavage. After that, a biochemical and histopathological studies were done.

RESULTS

Our results showed that lead exposure for three consecutive days increases significantly the 5-HT-immunoreactivity in dorsal raphe nucleus (DRN) accompanied with a significant enhancement of AVP-immunoreactivity in the cell bodies and fibers in the supraoptic (SON) and paraventricular (PVN) nuclei of the hypothalamus. In the collecting tube, AVP binds to the V2 receptor of the epithelial cells and increases the water permeability. Our results showed clearly the epithelial cells degeneration after lead exposure, then we suggest that the increased AVP could be a response to the hydric balance disrupted after degenerative effect of lead exposure on epithelial cells. BDMC produced an anxiolytic effect in meriones. Moreover, it restored 5-HT and AVP immunoreactivity within studying nuclei. The biochemical and histopathological studies showed that Pb induced renal damages. In addition, BDMC restored the renal alterations.

CONCLUSION

According to the obtained results, we suggest new pharmacological effects of BDMC; while it has an anxiolytic effect against Pb-induced anxiety by working on serotoninergic and vasopressinergic systems with an obvious restoration of the renal injuries induced by lead exposure.

Changes in Peritoneal Transport during the First Month of Peritoneal Dialysis

Objective

To determine if peritoneal transport characteristics change during the initial month of peritoneal dialysis.

Design

Retrospective review of peritoneal equilibration test (PET) results in patients who received their first PET during the first two weeks of peritoneal dialysis (early PET group) versus patients who received their first PET between four and 28 weeks after the initiation of dialysis (late PET group). The initial PET values were compared to subsequent PET results obtained approximately seven months after the initial PET.

Setting

Peritoneal dialysis unit of a tertiary medical center.

Outcome Measures

PET results and calculated mass transfer area coefficient (MT AC) values.

Patients

Thirty-four peritoneal dialysis patients in the early PET group and 17 peritoneal dialysis patients in the late PET group.

Results

In the early PET group, there was a statistically significant increase from the initial to follow-up values for both dialysate-to-plasma (DIP) creatinine and MTAC creatinine (p < 0.01) as well as a significant decrease for four-hour dialysate to initial dialysate ratios (DID) glucose (p = 0.08) and MTAC glucose (p < 0.05). In the late PET group, there was no significant change in any of these parameters with time. However, in the late PET group, there was a significant decrease in DIP urea values with time (p < 0.01), but not with MTAC urea. In addition, there were no differences over time in either group for serum albumin or hematocrit values.

Conclusion

During the first two weeks of peritoneal dialysis, there tends to be a change in peritoneal transport characteristics in some patients. PET data obtained during this time period should be interpreted as preliminary.

Oral Neostigmine and Lymphatic Absorption in a Myasthenia Gravis Patient on Continuous Ambulatory Peritoneal Dialysis (CAPD)

The effects of oral neostigmine on peritoneal lymph absorption and transcapillary and net ultrafiltration were studied in a myasthenia gravis patient on continuous ambulatory peritoneal dialysis (CAPD). Oral neostigmine decreased lymphatic absorption, but only up to a threshold dose. The effect on net ultrafiltration however was nullified to some extent by a concurrent decrease in cumulative transcapillary ultrafiltration.

The Need for Using An Enzymatic Colorimetric Assay in Creatinine Determination of Peritoneal Dialysis Solutions

The fate of the peritoneal membrane on continuous ambulatory peritoneal dialysis (CAPD) is usually evaluated through the modification of its permeability to various solutes as glucose, creatinine, and urea. Therefore, the accuracy of the methods used for measurements of creatinine is of great importance. A particular problem does exist for creatinine determination as it may be influenced by the presence of glucose.

We studied a new enzymatic colorimetric method for creatinine determination in peritoneal dialysis solutions which contain high dextrose concentrations. Creatinine was measured in plasma, urine, and dialysate from 18 patients on CAPD and in pure dextrose solutions, with an enzymatic test (Boehringer Mannheim) and with Jaffe's reaction on two different analyzers: Astra (Beckman) and Eris (Merck).

Creatinine results were similar with both assays (Jaffe's reaction and enzymatic test) when measured in blood and urine. However the Jaffe's reaction gave higher creatinine results than the enzymatic test (p < 0.001), when assays were performed in peritoneal dialysis solutions and in pure glucose solutions.

In addition, it appeared that other components of dialysis solutions, mainly calcium chloride, influenced unpredictably the results of creatinine with the Jaffe's reaction.

We conclude that specific enzymatic test is a more accurate and reliable method to evaluate creatinine kinetics through the peritoneal membrane when determined in CAPD solutions.

Assessment of Dialysis Dose by Measured Clearance versus Extrapolated Data

Objective

To determine whether estimates of daily dialysis clearance of creatinine and urea, based on data from the 4-hour peritoneal equilibration test, correlate well with daily dialysis clearance measured by 24-hour dialysate collection in chronic ambulatory peritoneal dialysis patients.

Design

Prospective study in which each subject collected all dialysate from a 24-hour period and then immediately thereafter underwent a standard peritoneal equilibration test (PET). Daily clearances of creatinine and urea were calculated from 24-hour dialysate collections by standard methods and then were compared with several estimates of 24-hour clearance based on PET data.

Setting

Single peritoneal dialysis unit of a university teaching hospital.

Patients

Thirty-six stable patients on continuous ambulatory peritoneal dialysis (CAPD).

Main Outcome

The estimated values for daily dialysis clearance both overestimated and underestimated the measured 24-hour clearance. The correlation coefficient between the extrapolations and the actual 24-hour clearances ranged from 0.63–0.68. The range of discordance for daily creatinine clearance was from -2530 mL/dayto +2199 mL/day. For daily urea clearance, the range of discordance was from -21 03 mL/ day to +1940 mL/day. The peritoneal membrane transport characteristics of the individual patient did not predict whether the extrapolation overestimated orunder estimated the measured daily clearance.

Conclusion

Extrapolation of PET data is not a reliable method to estimate the dose of dialysis delivered to the patient. A 24-hour collection of dialysis is necessary for this determination.

Variability in Creatinine Clearance (Ccr) and Ktn Due to Different Methods of Calculating Volume and Ccr

Objective

This study aimed to compare the correlations between KTN and creatinine clearance (Ccr) calculated by different methods and to determine and compare the correlations between KTN and Ccr.

Design

Nonrandomized, retrospective analysis of data.

Setting

Continuous ambulatory peritoneal dialysis (CAPD) outpatient clinic in a teaching hospital.

Patients

All patients were included for analysis if the data collection was complete for the calculations of KTN and Ccr using five different methods.

Interventions

Volume of distribution for urea (V) was estimated by four methods: Watson nomogram, ideal body weight (IBW), actual body weight, and total body surface area. Ccr was determined by five methods: Dialysate Ccr was calculated by creatinine (Cr) uncorrected and corrected for the presence of glucose; urinary Ccr was calculated using urinary Cr alone and the average urinary clearance of urea and Cr; and by the Cockcroft and Gault method.

Main Outcome Measures

Correlations between KTN and Ccr.

Results

Sixty-three data sets were collected from 52 CAPD patients. The correlations between weekly KTN and Ccr normalized to 1.73 m2 body surface area were found to be highly variable from one method to another (r2 = 0.012 -0.494). For obese patients (20% above IBW), KTN values obtained were more variable using the Watson nomogram compared to the IBW and BSA methods.

Conclusion

KT/V calculated using the Watson nomogram and the Ccr determined using average of urinary urea and creatinine clearance gave the best correlation (r2 = 0.49).

Factors Affecting Lymphatic Absorption in Chinese Patients on Continuous Ambulatory Peritoneal Dialysis (CAPD)

The pathways and physiology of lymph absorption (LA) from the peritoneal cavity are well documented; however, much uncertainty still exists as to the various clinical and demographic factors affecting LA. We studied LA measured by the albumin instillation method, in adult Chinese CAPD patients, and showed that it was independent of age, sex, body surface area, duration of dialysis, intrinsic renal disease, use of intraperitoneal drugs (heparin/antibiotics/deferroxamine) and frequency of past bacterial peritonitis. High lymph absorbers had a relatively highertranscapillary cumulative ultrafiltration than low lymph absorbers. An enhanced LA was associated with a high initial intraperitoneal volume. Assessment of diaphragmatic strength by the decrement in vital capacity on changing from an erect to a supine position failed to distinguish patients with high and low LA.

24-Hour Dialysate Collection for Determination of Peritoneal Membrane Transport Characteristics: Longitudinal Follow-Up Data for the Dialysis Adequacy and Transport Test (Datt)

Objective

To determine the ability of the dialysis adequacy and transport test (DATT) to monitor changes in peritoneal transport characteristics over time.

Setting

University-based peritoneal dialysis program.

Patients

One hundred patients on continuous ambulatory peritoneal dialysis who underwent 226 simultaneous DATTs and peritoneal equilibration tests (PET).

Methods

Retrospective analysis of DA TT and PET data.

Results

The mean 24-hour dialysate-to-plasma creatinine (cr) concentration ratio (DIP cr) from the DATT was 0.70±0.10, and the mean four-hour DIP crfrorn the PET was 0.68 ± 0.10. The correlation coefficient between the fourhour and 24-hour DIP cr was 0.81, and the standard error of estimate was 0.065. The mean (±SD) difference between the four-hour and 24-hour DIP cr was 0.023 ± 0.061. Fifty eight patients had two or more sequential DA TTs and PETs. For these 94sets of sequential DATTs and PETs, the mean (±SD) difference between the change in the four-hour DIP cr and the change in the 24-hour DIP cr was 0.020 ± 0.024, and the standard error of estimate was 0.064. In 17 patients a change in dwell volume from 2.0 L to 2.5 L occurred between the first and second measures of peritoneal membrane transport characteristics. The mean (±SD) difference between the change in the four-hour DIP cr and the change in the 24-hour DIP cr was 0.036 ± 0.055, and the standard error of estimate was 0.087.

Conclusion

The DATT can be used to monitor for changes in peritoneal transport over time. It should not be used in patients receiving cycler therapy or in patients whose dwell times and dextrose concentrations vary markedly from day to day.

Diagnostic utility of protein to creatinine ratio (P/C ratio) in spot urine sample within routine clinical practice

The spot (random) urine protein to creatinine ratio (P/C ratio) is an alternative, fast and simple method of detecting and estimating the quantitative assessment of proteinuria. The aim of the work was to review the literature concerning the usefulness of spot urine P/C ratio evaluation in the diagnosis of proteinuria in the course of kidney disease, hypertension, gestational hypertension, preeclampsia, immunological diseases, diabetes mellitus, and multiple myeloma, and in the diagnosis of proteinuria in children. We searched the PubMed and Google Scholar databases using the following keywords: proteinuria, spot urine protein to creatinine ratio, spot urine P/C ratio, protein creatinine index, PCR (protein to creatinine ratio), P/C ratio and methods, Jaffe versus enzymatic creatinine methods, urine protein methods, spot urine protein to creatinine ratio versus ACR (albumin to creatinine ratio), proteinuria versus albuminuria, limitations of the P/C ratio. More weight was given to the articles published in the last 10-20 years. A spot urine P/C ratio >20 mg/mmol (0.2 mg/mg) is the most commonly reported cutoff value for detecting proteinuria, while a P/C ratio value >350 mg/mmol (3.5 mg/mg) confirms nephrotic proteinuria. The International Society for the Study of Hypertension in Pregnancy recommends a P/C ratio of 30 mg/mmol (0.3 mg/mg) for the classification of proteinuria in pregnant women at risk of preeclampsia. A high degree of correlation was observed between P/C ratio values and the protein concentration in 24-h urine collections. The spot urine P/C ratio is a quick and reliable test that can eliminate the need for a daily 24-h urine collection. However, in doubtful situations, it is still recommended to assess proteinuria in a 24-h urine collection. The literature review indicates the usefulness of the spot P/C ratio in various disease states; therefore, this test should be available in every laboratory. However, the challenge for the primary care physician is to know the limitations of the methods used to determine the protein and creatinine concentrations that are used to calculate the P/C ratio. Moreover, the P/C ratio cutoff used should be determined in individual laboratories because it depends on the patient population and the laboratory methodologies.

Creatinine: From physiology to clinical application

Estimating static kidney function accurately and detecting changes in kidney function in a timely fashion are challenging but critically important tasks. Serum creatinine is the most widely used functional biomarker of the kidney. However, its use is associated with substantial shortcomings. Understanding these shortcomings is critical in allowing accurate interpretation of creatinine values and translating them into changes in kidney function. In this review, the pathways involved in creatinine generation and metabolism as well as the techniques involved in measuring creatinine concentrations are discussed. This allows for the discussion of the value and pitfalls in using creatinine as a marker of kidney function. In addition, information regarding alternative functional biomarkers of the kidney is provided.

Serum and Urinary Hepcidin for Diagnosing Iron-deficiency Anemia in Under-5 Children

Bone marrow iron estimation remains the gold standard for diagnosing iron-deficiency anemia (IDA); serum ferritin, total iron-binding capacity, and transferrin saturation are routinely used as surrogate markers of IDA. However, these tests are marred by problems like poor specificity and sensitivity. Recently, hepcidin, a protein hormone synthesized in the liver and excreted in urine, has been shown to be related to iron status. We estimated the serum and urinary hepcidin levels in healthy children 6 to 60 months of age with (n=30) and without IDA (n=30). The mean (SD) serum hepcidin levels in children with IDA were significantly lower than those in children without IDA (3.03 [1.06] vs. 4.78 [3.94] ng/mL; P=0.02). The mean (SD) urinary hepcidin levels were also significantly lower in children with IDA than those in children without IDA (2.29 [0.53] vs. 2.79 [0.75] ng/mL; P=0.004). Performance of urinary and serum hepcidin compared with serum ferritin (<12 µg/L) for diagnosing IDA in terms of area under the receiver operating characteristic curve was 0.704 (P=0.007) and 0.59 (P=0.22), respectively. Serum hepcidin is not useful for diagnosing IDA in under-5 children. In contrast, urinary hepcidin holds promise as a noninvasive diagnostic tool for IDA in under-5 children.

Phytochemical evaluation of roots of Plumbago zeylanica L. and assessment of its potential as a nephroprotective agent

Search for medicinal plants to treat kidney disorders is an important topic on phytotherapeutical research. Plumbago zeylanica L. is an important medicinal plant with hepatoprotective, anti-inflammatory, anti-diabetic, anti-cancer and anti-hyperlipidemic activities. In the present study, the protective effect of hydroalcoholic extract of P. zeylanica (HAPZ) in cisplatin induced nephrotoxicity was analyzed in Swiss albino mice. Treatment with higher dose (400 mg/kg) of HAPZ significantly reversed the adverse effect of cisplatin on kidney weight, serum urea and creatinine, indicating their renoprotective effect. The antioxidant effect of the drug is evident from its significant effect on Catalase, Glutathione peroxidase and lipid peroxidation activities.

Effect of obesity and glycated hemoglobin on oxygen saturation in ambulatory type 2 diabetic individuals: A pilot study

AIMS

Tissue hypoxia is an important contributor to diabetic complications. Glycation of hemoglobin (Hb) and obesity are major determinant of oxygen saturation (SpO2) in blood. Hence, the present study was planned to evaluate the effect of obesity on SpO2 in a wide range of glycated hemoglobin (HbA1c) levels in ambulatory type 2 diabetic patients.

MATERIAL AND METHODS

A cohort of 60 subjects irrespective of diabetic status were recruited and clustered in group I (HbA1c <6.5) and group II (HbA1c ≥6.5) depending on HbA1c. Anthropometry and routine biochemical parameters were measured. HbA1c (%) were estimated by high performance liquid chromatography (HPLC) respectively. SpO2 (%) levels were measured by pulse oximetry. Pearson correlation, bivariate regression and student 't' test were used for statistical analysis.

RESULTS

Blood concentration of HbA1c was <6.5 in 29 participants and ≥6.5 in 31 participants. Plasma fasting and post prandial glucose, HbA1c as well as Hb levels were significantly (p<0.50) higher in diabetics as compared to non diabetics. Waist circumference (WC) (r=-400; p=0.026) and body mass index (BMI) (r=-381; p=0.034) showed a significant negative correlation with SpO2 in diabetic patients. On adjusting HbA1c in group II, SpO2 was found to independently and inversely associated with WC (p=0.042) and BMI (p=0.049).

CONCLUSIONS

Obesity was found to be a strong independent contributor to reduction in oxygen carrying capacity in ambulatory type 2 diabetic subjects. However there is no effect of glycated Hb on SpO2 in the same population.

Higher Urinary Levels of 8-Hydroxy-2'-deoxyguanosine Are Associated with a Worse RANKL/OPG Ratio in Postmenopausal Women with Osteopenia

Postmenopausal osteoporosis (PO) is a major public health issue which affects a large fraction of elderly women. Emerging in vitro evidence suggests a central role of oxidative stress (OxS) in postmenopausal osteoporosis (PO) development. Contrariwise, the human studies on this topic are still scarce and inconclusive. In the attempt to address this issue, we sought to determine if OxS, as assessed by 8-hydroxy-2-deoxyguanosine (8-OHdG), may influence the level of receptor activator of nuclear factor-κb ligand (RANKL)/osteoprotegerin (OPG) ratio (a central regulator of bone metabolism) in a sample (n = 124), including postmenopausal women with osteoporosis, osteopenia and normal bone mass density (BMD). The most striking result that emerged in our study was the independent and positive (beta = 0.449, p = 0.004, and R² = 0.185) association between the OxS marker and RANKL/OPG ratio which was found in osteopenic but not in the other 2 sample groups. If confirmed by longitudinal studies, our findings would suggest that OxS is implicated in the derangement of bone homeostasis which precedes PO development. In line with these considerations, antioxidant treatment of postmenopausal women with moderately low BMD might contribute to preventing PO and related complications.

Association of tumor necrosis factor (TNF) promoter polymorphisms with plasma TNF-α levels and susceptibility to diabetic nephropathy in North Indian population

AIM

The concept of diabetic nephropathy (DN) as a metabolic disease is now being replaced by chronic low-grade inflammatory disease. Tumor necrosis factor-alpha (TNF-α) is a proinflammatory cytokine which plays an important role in the pathogenesis and clinical outcome of DN. Therefore, this work was planned to evaluate the association of -863C/A (rs1800630) and -1031T/C (rs1799964) polymorphisms in TNF gene with plasma TNF-α levels and DN among subjects with type 2 diabetes (T2DM) in a population from North India.

METHODS

Age and sex matched 100 healthy controls (HC), 100 T2DM subjects without nephropathy (DM) and 100 subjects with DN were screened for above polymorphisms using the PCR-RFLP methods. Plasma TNF-α levels were measured by ELISA. Analysis of variance and logistic regression were used to associate individual polymorphisms with plasma TNF-α levels and DN.

RESULTS

The allelic frequencies of -863C/A were 0.86/0.14 in HC, 0.72/0.23 in DM and 0.84/0.16 in DN, and that of -1031T/C were 0.89/0.11 in HC, 0.95/0.05 in DM and 0.80/0.20 in DN. The carriers of -863A allele had significantly lower plasma TNF-α levels (p<0.05). The -863C/A (OR=0.439, 95% CI=0.244-0.789, p=0.006) and -1031T/C (OR=3.0, 95% CI=1.355-6.642, p=0.007) were strongly associated with risk of development of DN.

CONCLUSIONS

-863C/A was associated with low whereas -1031T/C with high TNF-α levels. The, results suggest that -863C/A polymorphism might be protective whereas -1031T/C may be associated with increased risk for DN in subjects with T2DM from North India.

Calibration and precision of serum creatinine and plasma cystatin C measurement: impact on the estimation of glomerular filtration rate

Serum creatinine (SCr) is the main variable for estimating glomerular filtration rate (GFR). Due to inter-assay differences, the prevalence of chronic kidney disease (CKD) varies according to the assay used, and calibration standardization is necessary. For SCr, isotope dilution mass spectrometry (IDMS) is the gold standard. Systematic differences are observed between Jaffe and enzymatic methods. Manufacturers subtract 0.30 mg/dl from Jaffe results to match enzymatic results ('compensated Jaffe method'). The analytical performance of enzymatic methods is superior to that of Jaffe methods. In the original Modification of Diet in Renal Disease (MDRD) equation, SCr was measured by a Jaffe Beckman assay, which was later recalibrated. A limitation of this equation was an underestimation of GFR in the high range. The Chronic Kidney Disease Epidemiology (CKD-EPI) consortium proposed an equation using calibrated and IDMS traceable SCr. The gain in performance was due to improving the bias whereas the precision was comparable. The CKD-EPI equation performs better at high GFR levels (GFR >60 ml/min/1.73 m(2)). Analytical limitations have led to the recommendation to give a grade (>60 ml/min/1.73 m(2)) rather than an absolute value with the MDRD equation. By using both enzymatic and calibrated methods, this cutoff-grade could be increased to 90 ml/min/1.73 m(2) (with MDRD) and 120 ml/min/1.73 m(2) (with CKD-EPI). The superiority of the CKD-EPI equation over MDRD is analytical, but the precision gain is limited. IDMS traceable enzymatic methods have been used in the development of the Lund-Malmö (in CKD populations) and Berlin Initiative Study equations (in the elderly). The analytical errors for cystatin C are grossly comparable to issues found with SCr. Standardization is available since 2011. A reference method for cystatin C is still lacking. Equations based on standardized cystatin C or cystatin C and creatinine have been proposed. The better performance of these equations (especially the combined CKD-EPI equation) has been demonstrated.

Haemodialysing babies weighing <8 kg with the Newcastle infant dialysis and ultrafiltration system (Nidus): comparison with peritoneal and conventional haemodialysis

BACKGROUND

To compare the efficacy of the Newcastle infant dialysis and ultrafiltration system (Nidus) with peritoneal dialysis (PD) and conventional haemodialysis (HD) in infants weighing <8 kg.

METHODS

We compared the urea, creatinine and phosphate clearances, the ultrafiltration precision, and the safety of the Nidus machine with PD in 7 piglets weighing 1-8 kg, in a planned randomised cross-over trial in babies, and in babies for whom no other therapy existed, some of whom later graduated to conventional HD.

RESULTS

Two babies entered the randomised trial; 1 recovered rapidly on PD, the other remained on the Nidus as PD failed. Additionally, 9 babies were treated on the Nidus on humanitarian grounds: 3 because of failed PD, and 3 with permanent kidney failure later converted to conventional HD. We haemodialysed 10 babies weighing between 1.8 and 5.9 kg for 2,475 h during 354 Nidus sessions without any clinically important incidents, and without detectable haemolysis. Single-lumen vascular access was used with no blood priming of circuits. The urea, creatinine and phosphate clearances using the Nidus were around 1.5 to 2.0 ml/min in piglets and babies, and were consistently higher than PD clearances, which ranged from about 0.2 to 0.8 ml/min (p ≤ 0.0002 for each chemical). Ultrafiltration was achieved to microlitre precision by the Nidus, but varied widely with PD. Fluid removal using conventional HD was imprecise and resulted in some hypovolaemic episodes requiring correction.

CONCLUSION

The Nidus can provide HD in the Pediatric Intensive Care Unit (PICU) and outpatient intermittent HD without blood priming for babies weighing <8 kg, It generates higher dialysis clearances than PD, and delivers more precise ultrafiltration control than either PD or conventional HD.

The effects of S-nitrosoglutathione and S-nitroso-N-acetyl-D, L-penicillamine in a rat model of pre-eclampsia

BACKGROUND

Pre-eclampsia (PE) complicates approximately 5-7% of all pregnancies. This study investigates the effects of S-nitroso-N-acetylpenicillamine (SNAP) and S-nitrosoglutathione (GSNO) on the classical features of PE.

MATERIALS AND METHODS

On day 14 of gestation, female Sprague-Dawley rats were separated into five groups and treated intravenously for 7 days as follows: (i) 0.3 mL 0.9% saline (control, n = 11); (ii) 50 mg/kg Body Weight (BW) N-nitro-L-arginine methyl ester (L-NAME) in 0.3 mL saline (n = 10); (iii) 50 mg/kg BW L-NAME and 8 mg/kg BW GSNO in 0.15 mL saline (n = 6); (iv) 50 mg/kg BW L-NAME in 0.15 mL saline and 8 mg/kg BW SNAP in 0.15 mL DMSO (n = 9); and (v) 0.15 mL DMSO and 0.15 mL saline (SNAP control, n = 7). Blood pressures were measured on day 14 through day 20, a 4-h urine sample was taken on day 20, and animals were sacrificed on day 21. Pups were counted and weighed individually.

RESULTS

SNAP and GSNO significantly decreased systolic, diastolic, and mean arterial pressures in PE-induced rats from day 14 through day 20 (P < 0.05). Pup weights in SNAP and GSNO groups were higher than in L-NAME group but lower than in controls (P ≤ 0.001). SNAP and GSNO partially reversed growth retardation.

CONCLUSION

Elevated blood pressure, proteinuria, and intrauterine growth restriction associated with PE were induced in Sprague-Dawley rats using L-NAME. These were partially reversed with the use of GSNO and SNAP. The mechanism of action of these S-nitrosothiols (RSNOs) should be further explored.

Gene therapy for mucopolysaccharidosis type VI is effective in cats without pre-existing immunity to AAV8

Liver gene transfer with adeno-associated viral (AAV) 2/8 vectors is being considered for therapy of systemic diseases like mucopolysaccharidosis type VI (MPS VI), a lysosomal storage disease due to deficiency of arylsulfatase B (ARSB). We have previously reported that liver gene transfer with AAV2/8 results in sustained yet variable expression of ARSB. We hypothesized that the variability we observed could be due to pre-existing immunity to wild-type AAV8. To test this, we compared the levels of AAV2/8-mediated transduction in MPS VI cats with and without pre-existing immunity to AAV8. In addition, since levels of lysosomal enzymes as low as 5% of normal are expected to be therapeutic, we evaluated the impact of pre-existing immunity on MPS VI phenotypic rescue. AAV2/8 administration to MPS VI cats without pre-existing neutralizing antibodies to AAV8 resulted in consistent and dose-dependent expression of ARSB, urinary glycosaminoglycan (GAG) reduction, and femur length amelioration. Conversely, animals with pre-existing immunity to AAV8 showed low levels of ARSB expression and limited phenotypic improvement. Our data support the use of AAV2/8-mediated gene transfer for MPS VI and other systemic diseases, and highlight that pre-existing immunity to AAV8 should be considered in determining subject eligibility for therapy.

Clinical evaluation of analytical variations in serum creatinine measurements: why laboratories should abandon Jaffe techniques

BACKGROUND

Non-equivalence in serum creatinine (SCr) measurements across Dutch laboratories and the consequences hereof on chronic kidney disease (CKD) staging were examined.

METHODS

National data from the Dutch annual external quality organization of 2009 were used. 144 participating laboratories examined 11 pairs of commutable, value-assigned SCr specimens in the range 52-262 μmol/L, using Jaffe or enzymatic techniques. Regression equations were created for each participating laboratory (by regressing values as measured by participating laboratories on the target values of the samples sent by the external quality organization); area under the curves were examined and used to rank laboratories. The 10th and 90th percentile regression equation were selected for each technique separately. To evaluate the impact of the variability in SCr measurements and its eventual clinical consequences in a real patient population, we used a cohort of 82424 patients aged 19-106 years. The SCr measurements of these 82424 patients were introduced in the 10th and 90th percentile regression equations. The newly calculated SCr values were used to calculate an estimated glomerular filtration rate (eGFR) using the 4-variable Isotope Dilution Mass Spectrometry traceable Modification of Diet in Renal Disease formula. Differences in CKD staging were examined, comparing the stratification outcomes for Jaffe and enzymatic SCr techniques.

RESULTS

Jaffe techniques overestimated SCr: 21%, 12%, 10% for SCr target values 52, 73 and 94 μmol/L, respectively. For enzymatic assay these values were 0%, -1%, -2%, respectively. eGFR using the MDRD formula and SCr measured by Jaffe techniques, staged patients in a lower CKD category. Downgrading to a lower CKD stage occurred in 1-42%, 2-37% and 12-78.9% of patients for the 10th and 90th percentile laboratories respectively in CKD categories 45-60, 60-90 and >90 ml/min/1.73 m2. Using enzymatic techniques, downgrading occurred only in 2-4% of patients.

CONCLUSIONS

Enzymatic techniques lead to less variability in SCr measurements than Jaffe techniques, and therefore result in more accurate staging of CKD. Therefore the specific enzymatic techniques are preferably used in clinical practice in order to generate more reliable GFR estimates.

Differential effects of two citrus flavanones on bone quality in senescent male rats in relation to their bioavailability and metabolism

The effect of hesperidin (Hp) and naringin (Nar), two major citrus flavanones, on the regulation of bone metabolism was examined in male senescent rats. Twenty -month -old gonad-intact male Wistar rats received a casein-based diet supplemented with or without either 0.5% hesperidin (Hp), 0.5% naringin (Nar) or a mix of both flavanones (Hp+Nar, 0.25% each). After 3 months, daily Hp intake significantly improved femoral bone integrity as reflected by improvements in total and regional bone mineral densities (BMD) (9.7%-12.3% improvements, p<0.05) and trabecular bone volume fraction (24.3% improvement, p<0.05) at the femur compared with control group. In contrast, naringin exerted site-specific effects on BMD (10.2% improvement at the distal metaphyseal area, p<0.05) and no further benefit to bone mass was observed with the mix of flavanones. Bone resorption (DPD) was significantly attenuated by Hp and Nar given alone (40.3% and 26.8% lower compared to control, p<0.05, respectively) but not by the mixture of the two. All treatments significantly reduced expression of inflammatory markers to a similar extent (IL-6, 81.0-87.9% reduction; NO, 34.7-39.5% reduction) compared to control. Bone formation did not appear to be strongly affected by any of the treatments (no effect on osteocalcin levels, modest modulation of tibial BMP-2 mRNA). However, as previously reported, plasma lipid-lowering effects were observed with Hp and Nar alone (34.1%-45.1% lower for total cholesterol and triglycerides compared to control, p<0.05) or together (46% lower for triglycerides, p<0.05). Surprisingly the plasma circulating level of naringin (8.15μM) was >5-fold higher than that of hesperidin (1.44μM) at equivalent doses (0.5%) and a linear reduction in plasma levels was observed upon co-administration (0.25% each) indicating absence of competition for their intestinal absorption sites and metabolism. The higher efficacy of Hp at a lower plasma concentration than naringin, as well as the identification of the major circulating metabolite of hesperidin (hesperetin-7-O-glucuronide) underlines the importance of flavanone bioavailability and metabolism in their biological efficacy and suggests a structure-function relationship in the mechanism of action of the active metabolites.

Point-of-care measurement of serum creatinine in the intensive care unit

OBJECTIVE

To test the precision and limits of agreement of point-of-care testing (POCT)-based measurement of serum creatinine (Cr) in critically ill patients.

METHODS

We studied 250 paired blood samples from 82 critically ill patients from a general intensive care unit by simultaneous POCT and central laboratory testing (Jaffé method). Correlation, precision, bias, and limits of agreement were assessed. Possible confounders for interference of noncreatinine chromogens were evaluated by multivariate linear regression analysis.

RESULTS

The mean difference in serum Cr measured by central laboratory and POCT was +9.6 μmol/L (95% limits of agreement: -11.2 to +30.4 μmol/L). The mean percentage difference between the two techniques was 8.7% (95% limits of agreement -7.8% to +25.1%). On multivariate regression, the difference in serum Cr was increased with greater hemoglobin and lactate levels but decreased with greater bilirubin, albumin, and calcium levels.

CONCLUSIONS

Compared with the central laboratory testing, POCT-based measurement of serum Cr in critically ill patients carried a small negative bias. This difference appeared affected by the blood levels of biochemical variables known to affect the Jaffé method. POCT-based Cr measurement appears sufficiently accurate for clinical use.

Increased bioavailability of hesperetin-7-glucoside compared with hesperidin results in more efficient prevention of bone loss in adult ovariectomised rats

Hesperidin (Hp), a citrus flavonoid predominantly found in oranges, shows bone-sparing effects in ovariectomised (OVX) animals. In human subjects, the bioavailability of Hp can be improved by the removal of the rhamnose group to yield hesperetin-7-glucoside (H-7-glc). The aim of the present work was to test whether H-7-glc was more bioavailable and therefore more effective than Hp in the prevention of bone loss in the OVX rat. Adult 6-month-old female Wistar rats were sham operated or OVX, then pair fed for 90 d a casein-based diet supplemented or not with freeze-dried orange juice enriched with Hp or H-7-glc at two dose equivalents of the hesperetin aglycone (0·25 and 0·5 %). In the rats fed 0·5 %, a reduction in OVX-induced bone loss was observed regarding total bone mineral density (BMD):+7·0 % in OVX rats treated with Hp (HpOVX) and +6·6 % in OVX rats treated with H-7-glc (H-7-glcOVX) v. OVX controls (P < 0·05). In the rats fed 0·25 % hesperetin equivalents, the H-7-glcOVX group showed a 6·6 % improvement in total femoral BMD v. the OVX controls (P < 0·05), whereas the Hp diet had no effect at this dose. The BMD of rats fed 0·25 % H-7-glc was equal to that of those given 0·5 % Hp, but was not further increased at 0·5 % H-7-glc. Plasma hesperetin levels and relative urinary excretion were significantly enhanced in the H-7-glc v. Hp groups, and the metabolite profile showed the absence of eriodictyol metabolites and increased levels of hesperetin sulphates. Taken together, improved bioavailability of H-7-glc may explain the more efficient bone protection of this compound.

Major phenolic compounds in olive oil modulate bone loss in an ovariectomy/inflammation experimental model

This study was conducted to determine whether the daily consumption for 84 days of tyrosol and hydroxytyrosol, the main olive oil phenolic compounds, and olive oil mill wastewater (OMWW), a byproduct of olive oil production, rich in micronutrients, may improve bone loss in ovariectomized rats (an experimental model of postmenopausal osteoporosis) and in ovariectomized rats with granulomatosis inflammation (a model set up for senile osteoporosis). As expected, an induced chronic inflammation provoked further bone loss at total, metaphyseal, and diaphyseal sites in ovariectomized rats. Tyrosol and hydroxytyrosol prevented this osteopenia by increasing bone formation ( p < 0.05), probably because of their antioxidant properties. The two doses of OMWW extracts had the same protective effect on bone ( p < 0.05), whereas OMWW did not reverse established osteopenia. In conclusion, polyphenol consumption seems to be an interesting way to prevent bone loss.

Influence of lifelong soy isoflavones consumption on bone mass in the rat

Soy isoflavones (IFs) have shown a bone-sparing effect through epidemiological studies in the Asian population. However, there is no evidence as to whether such protection would result from a lifelong exposure. We investigated the impact of an early exposure to IFs on bone status. Sixty female Wistar rats were fed either a standard diet (n=30) or the same food enriched with IFs (0.87 mg/g of diet) (n=30). After 1 month, they were allowed to mate, and were kept on the same regimen during the whole gestation and lactation periods. At weaning, female pups were each assigned to one of four nutritional groups; within each experimental group, animals were split into two groups, fed either the standard or the IF-rich diet. At 2, 3, 6, 12, 18, and 24 months after birth, 10 animals in each group were sacrificed. Femurs were collected for mechanical testing and bone mineral density (BMD) measurement. The rats perinatally or lifelong exposed to the IF-rich diet exhibited higher body weight and fat mass at 24 months of age. Peak bone mass was achieved between 6 and 12 months and did not differ between groups. In animals perinatally exposed to IF, BMD continued to increase. Thus, at 24 months, femoral total BMD (P<0.05), metaphyseal BMD (P<0.01), and failure load (P<0.05) were higher in the offspring born from mothers provided IF during pregnancy. Postnatal exposure alone did not improve bone parameters. This experiment provides evidence that perinatal exposure to phytoestrogens leads to a higher BMD later in life. It is suggested that these changes may have occurred as a consequence of programming effects, as has been shown for the endocrine and immune systems.

Hesperidin inhibits ovariectomized-induced osteopenia and shows differential effects on bone mass and strength in young and adult intact rats

The main aim of this study was to investigate the bone-sparing effect of hesperidin, one of the main flavonoid present in oranges, in two age groups of ovariectomized female rats, compared with their intact controls. Young (3 mo) and adult (6 mo) female Wistar rats were sham operated (SH) or ovariectomized (OVX) and then pair-fed for 90 days a casein-based diet supplemented or not with 0.5% hesperidin (Hp; n = 10/group). In older rats, Hp intake led to a partial inhibition of OVX-induced bone loss, whereas a complete inhibition was obtained in younger animals. At both ages, while plasma osteocalcin concentrations were unchanged, urinary excretion of deoxypyridinoline was reduced by Hp intake, suggesting that Hp was able to slow down bone resorption. Unexpectedly, in intact young rats, Hp consumption resulted in a significant increase in bone mineral density (BMD). Indeed, 6-mo-old HpSH rats had a similar BMD to 9-mo-old nontreated SH adult rats, suggesting an accelerated bone mass gain in the young rats. In contrast, in intact adult rats, Hp did not further increase BMD but did improve their bone strength. The results of this study show a protective effect of Hp on bone loss in OVX rats of both ages without uterine stimulation and accompanied by a lipid-lowering effect. The unexpected and intriguing findings obtained in intact rats showing improved BMD in young rats and improved femoral load in adult rats merit further investigation. The bone and lipid benefits of hesperidin make it an attractive dietary agent for the management of the health of postmenopausal women.

Black Lucques olives prevented bone loss caused by ovariectomy and talc granulomatosis in rats

This study was conducted to determine whether olive fruits, rich in micronutrients, might improve bone loss in ovariectomized (OVX) rats (an experimental model of postmenopausal osteoporosis) and in OVX rats with granulomatosis inflammation (a model of senile osteoporosis). Six-month-old Wistar female rats underwent ovariectomy and were then immediately treated orally by substituting oil in the diet by 10 g/d green Lucques olives or 6 g/d black Lucques olives for each rat for 84 days. OVX rats and sham-operated controls received the same diet with oil. Three weeks before the end of the experiment, subcutaneous inflammation was provoked by injections of sterile magnesium silicate in half the animals in each group. In OVX rats, granulomatosis inflammation, characterized by a rise in inflammatory parameters such as fibrinogen, alpha1-acid glycoprotein, spleen weight and granulocyte level, and an impairment of oxidative status (as shown by a decrease in plasma antioxidant capacity, a higher rate of isoprostane excretion) elicited a bone loss in the whole femur and in the metaphyseal areas considered on their own. Whereas green olives had no effect on osteopenia, consumption of the black variety prevented bone loss in the whole femur and at cortical sites in those oestrogen-deficient animals with talc inflammation (diaphyseal bone mineral density: black olives and inflammation 0-2323 (SE 0.0026) v. ovariectomy and inflammation 0.2117 (SE 0.0030); P=0.027). This bone-sparing effect seemed to result from an improvement in the inflammatory and oxidative status. The present data show that black olives are able to prevent bone loss in an experimental model of senile osteoporosis (oestrogen-deficient rats in which a low-grade inflammation was induced by talc injection).

Increased DNA damage in children caused by passive smoking as assessed by comet assay and oxidative stress

The present study aimed to evaluate the association between the environmental tobacco smoke (ETS) and DNA damage in relation to oxidative stress (OS) in children. Sixty-four children of age 1-8 years, selected from the outpatient clinic of Mansoura University Children Hospital were divided into two groups (23 children/group) based on high (>20 cigarettes/day) or low (<20 cigarettes/day) exposure to ETS at home. Twenty symptom-free children with normal cotinine level and with no exposure to ETS were recruited as controls. The comet assay was used to quantify the level of DNA damage in lymphocytes isolated from all children. Spectrophotometric methods were used to assess the serum level of malondialdehyde (MDA) and activity of glutathione peroxidase (GSH-Px) in erythrocytes. Also, serum level of tocopherol fractions (alpha, gamma, delta) was assessed by high performance liquid chromatography (HPLC). Children exposed to ETS exhibited retarded growth, more chest problems, and gastroenteritis than the control. A significant increase in mean comet tail length indicating DNA damage was observed in ETS-exposed children (P<0.001) compared to controls. ETS-exposed children had significantly (P<0.001) higher MDA level paralleled with significant (P<0.001) decrease in the level of GSH-Px and tocopherol fractions compared with controls. The GSH-Px activity and tocopherol levels were inversely correlated with the increase of ETS exposure. These results show that inhalation of ETS is associated with an increase in the level of oxidants and a simultaneous decrease in the level of antioxidants in the children's blood. This status of oxidant-antioxidant imbalance (OS) may be one of the mechanisms leading to DNA damage detected in lymphocytes of ETS-exposed children. In conclusion, the present study gives an indication of an association between DNA damage and ETS exposure in children.

Modulation of soy isoflavones bioavailability and subsequent effects on bone health in ovariectomized rats: the case for equol

INTRODUCTION

Soy products are of particular interest because of their potential health benefits in a range of hormonal conditions, such as osteoporosis, due to their high content in phytoestrogens. Because equol, the main metabolite from soy isoflavones, is thought to be powerful, the present study was designated to evaluate the bone-sparing effects of equol by either providing the molecule through the diet or by eliciting its endogenous production by modulating intestinal microflora by short-chain fructooligosaccharides (sc-FOS) or live microbial (Lactobacillus casei) together with daidzein, its precursor.

METHODS

A comparison with daidzein and genistein was also performed. Rats (3 months old) were ovariectomised (OVX) or sham-operated (SH). Ovariectomised rats were randomly assigned to six experimental diets for 3 months: a control diet (OVX), the control diet supplemented with either genistein (G), or daidzein (D), or equol (E) at the level of 10 microg/g body weight/d. The remaining OVX rats were given daidzein at the dose of 10 mug/g body weight/d, simultaneously with short-chain FOS (Actilight, Beghin-Meiji) (D+FOS) or Lactobacillus casei (Actimel, Danone) (D+L). The SH rats were given the same control diet as OVX.

RESULTS

Genistein, daidzein or equol exhibited a bone sparing effect. Indeed, total femoral bone mineral density (BMD) was significantly enhanced (compared to that of OVX rats), as was the metaphyseal compartment. Bone strength was improved by E consumption, but not by genistein or daidzein given alone. As far as the FOS diet is concerned, the addition of prebiotics significantly raised efficiency of the daidzein protective effect on both femoral BMD and mechanical properties. The effects of lactobacillus were similar, except that the increase in metaphyseal-BMD was not significant.

CONCLUSION

In conclusion, long-term equol consumption, like genistein and daidzein, in the ovariectomized rat, provides bone sparing effects. Adding indigestible sugars, such as FOS or live microbial as L. casei, in the diet significantly improves daidzein protective effects on the skeleton.

Dose-response study of effect of oleuropein, an olive oil polyphenol, in an ovariectomy/inflammation experimental model of bone loss in the rat

BACKGROUND & AIMS

This study was carried out to assess the dose-dependent bone-sparing effect of oleuropein, an olive oil phenolic compound with anti-inflammatory and anti-oxidative properties, on bone loss induced by talc granulomatosis in oestrogen-deficient rat.

METHODS

Among 98 rats, 20 were sham-operated (SH) while the others (78) were ovariectomised (OVX). The SH and 26 OVX rats (controls) were given a standard diet for 100 days. The 52 remaining OVX rats were allocated to 4 groups that received oleuropein at 2.5, 5, 10 or 15 mg/kg body weight per day for 100 days. Three weeks before necropsy, an inflammation was induced by subcutaneous injections of talc in half of the SH and OVX rats and in all oleuropein-treated animals.

RESULTS

Castration was associated with a decreased bone mineral density (BMD). In OVX rats, inflammation, characterised by an increase of the spleen weight and plasma fibrinogen levels, exacerbated this bone loss, as shown by values of BMD of the total femur metaphyseal and diaphyseal subregions. The 4 doses of oleuropein reduced bone loss and improved inflammatory biomarkers excepted for 5mg/kg BW.

CONCLUSIONS

Every dose of oleuropein elicited protective effects on bone mass in this model of ovariectomy associated with inflammation, probably by modulating inflammatory parameters.

Flavonoids derived from herbal Epimedium Brevicornum Maxim prevent OVX-induced osteoporosis in rats independent of its enhancement in intestinal calcium absorption

AIM

Factorial design was used to test our hypothesis whether a group of flavonoids (FE) derived from herbal Epimedium Brevicornum Maxim exerted its preventive effects on estrogen-deficiency-induced osteoporosis mainly through an enhancement in intestinal calcium absorption.

MATERIALS AND METHODS

Forty-five 12-month-old female Wistar rats were used and randomly assigned into sham-operated group and four ovariectomy (OVX) subgroups, i.e. OVX with vehicle (OVX group), OVX with FE (FE group), OVX with calcium supplement (CS group), and OVX with FE and CS (FE + CS group). Daily oral administration of FE (10 mg/kg/day) and/or CS (56 mg/kg/day) started on day 4 after OVX for 12 weeks. Before sacrificing the animals, urine and serum samples were collected for assaying indicators related to intestinal calcium absorption, regulator for calcium homeostasis, and markers of bone turnover. The left proximal femur was dissected for evaluation of the primary end-point (failure force), the second end-points (pQCT-quantified densitometry, geometry, and micro-CT-quantified 3-D trabecula micro-architecture), and pQCT-defined cross-sectional envelope.

RESULTS

FE was found to be able to prevent OVX-induced reduction in failure force as well as the above second end-points, without resulting in an increased uterus weight. CS had no preventive effect on OVX-induced reduction in failure force. Two-way factorial interaction analysis between FE and CS showed that the un-enhanced suppression of parathyroid hormone for calcium homeostasis did not provide link between the enhanced intestinal calcium absorption and the enhanced inhibition of bone resorption in the present study. Furthermore, the discrepancies between the enhanced intestinal calcium absorption and the un-enhanced end-point measures as well as anabolic effect were also revealed by the interaction analysis.

CONCLUSION

The present study suggested that FE inhibited bone resorption, stimulated bone formation, and accordingly prevented osteoporosis without hyperplastic effect on uterus in the OVX rat model, which was however independent of an enhancement in intestinal calcium absorption.

Prevention of bone loss by phloridzin, an apple polyphenol, in ovariectomized rats under inflammation conditions

Aging and sex hormones related changes lead to inflammatory and oxidant conditions, which are involved in the pathogenesis of osteoporosis. Recent studies have suggested that polyphenols may exert a protective effect in such conditions. We assessed the effect of phloridzin (Phlo), a flavonoid exclusively found in apple, on bone metabolism in ovariectomized (OVX) or sham-operated (SH) rats with and without inflammation. Six-month-old Wistar rats were allocated to two equal groups that received either a control diet or a diet supplemented with 0.25% Phlo for 80 days. Three weeks before necropsy, inflammation was induced by subcutaneous injection of talc in 10 animals of each group. At necropsy, ovariectomy decreased both total (T-BMD) and metaphyseal (M-BMD) femoral bone mineral density (P < 0.01). Inflammation conditions, checked by an increase in the spleen weight and alpha1-acid glycoprotein concentration in OVX rats, exacerbated the decrease in T-BMD (g/cm2) (as well as M-BMD) observed in castrated animals (P < 0.05). Daily Phlo intake prevented ovariectomy-induced bone loss in conditions of inflammation as shown by T-BMD and M-BMD (P < 0.05). At the diaphyseal site, BMD was improved by Phlo in OVX rats with or without inflammation (P < 0.05). These results could be explained by changes in bone remodeling as the increased urinary deoxypyridinoline excretion in OVX and OVXinf animals was prevented by the polyphenol-rich diet (P < 0.001), while plasma osteocalcin concentration was similar in all experimental groups. In conclusion, Phlo consumption may provide protection against ovariectomy-induced osteopenia under inflammation conditions by improving inflammation markers and bone resorption.

Preventive effect of Abelmoschus manihot (L.) Medik. on bone loss in the ovariectomised rats

Because the biggest culprit in pathogenesis of osteoporosis is oestrogen deficiency, hormone replacement therapy remained the mainstay for prevention. However most of postmenopausal women are more inclined to use natural alternative. We thus investigated the ability of Abelmoschus manihot, a herbal medicine to prevent bone loss in ovariectomised rats. Female Wistar rats were sham operated (SH: 8) or ovariectomised (OVX: 24). On day 0, OVX rats were randomly assigned to groups as follows: eight received 10% Abelmoschus manihot leaves in their diet, eight were given 15% Abelmoschus manihot leaves and eight were untreated (OVX). Compounds were mixed with a soy protein-free diet and given orally for 3 months. At necropsy, bone mineral density (BMD) in the femur and in its metaphyseal zone was lower in OVX than SH (p<0.05). This osteopenia was prevented by consumption of the highest dose of Abelmoschus manihot leaves. Bone mineral content (BMC) in the total femur and its metaphyseal and diaphyseal subregions was improved, as well (p<0.05). This could be explained by a trend towards decreased bone resorption. The lowest dose did not elicit any significant effect. In conclusion, Abelmoschus manihot consumption, at the dose of 15% in the diet, provided bone-sparing effects by improving both BMD and BMC.

Determination of creatinine in urine by tandem mass spectrometry

BACKGROUND

Electrospray tandem mass spectrometry (TMS) is a very powerful tool that enables one to perform high sample throughput analysis. This paper describes a method to determine creatinine in urine by tandem mass spectrometry with direct sample infusion into an ion source.

METHODS

Samples (50 microl) were diluted with internal standard (IS) (450 microl of 0.667 mmol/l deuterated creatinine). Diluted samples were introduced into mass spectrometer with no prior pretreatment and after purification on ion-exchange 96-column cartridge. Tandem mass spectrometry analyses were performed in selected reaction monitoring mode. Creatinine and creatinine-d(3) were monitored using precursor and product ion settings (m/z 114 to 86 and m/z 117 to 89, respectively). The time of an analysis was 3.015 min. Both TMS methods were compared mutually and with the results obtained by enzymatic and Jaffe method.

RESULTS

Linearity was obtained in the range 0.06-60 mmol/l. Detection limit was 0.2 mumol/l and recoveries were in the range 95.1-98.3% for both the assays with and without ion-exchange column. Results of both assays are in good agreement with those obtained by enzymatic and Jaffe method based on log-transformed Bland-Altman plots. Electrospray tandem mass spectrometry method utilizing both approaches with and without ion-exchange column is acceptable according to CLIA criteria.

CONCLUSION

Tandem mass spectrometry allows rapid, sensitive and selective determination of creatinine in untreated urine.

Olive oil and its main phenolic micronutrient (oleuropein) prevent inflammation-induced bone loss in the ovariectomised rat

The present study was designed to evaluate the effect of olive oil and its main polyphenol (oleuropein) in ovariectomised rats with or without inflammation. Rats (6 months old) were ovariectomised or sham-operated as control. Ovariectomised rats were separated into three groups receiving different diets for 3 months: a control diet with 25 g peanut oil and 25 g rapeseed oil/kg (OVX), the control diet with 50 g olive oil/kg or the control diet with 0.15 g oleuropein/kg. The sham-operated group was given the same control diet as OVX. Inflammation was induced 3 weeks before the end of the experiment by subcutaneous injections of talc (magnesium silicate) in one-half of each group. The success of ovariectomy was verified at necropsy by the atrophy of uterine horns. Inflammation, oleuropein or olive oil intakes did not have any uterotrophic activity, as they had had no effect on uterus weight. The plasma concentration of alpha-1-acid glycoprotein (an indicator of inflammation) was increased in OVX rats with inflammation. With regard to bone variables, osteopenia in OVX was exacerbated by inflammation, as shown by a decrease in metaphyseal and total femoral mineral density. Both oleuropein and olive oil prevented this bone loss in OVX rats with inflammation. At necropsy, oleuropein and olive oil consumption had had no effect on plasma osteocalcin concentrations (marker of bone formation) or on urinary deoxypyridinoline excretion (marker of bone resorption). In conclusion, oleuropein and olive-oil feeding can prevent inflammation-induced osteopenia in OVX rats.

Chocolate intake increases urinary excretion of polyphenol-derived phenolic acids in healthy human subjects

BACKGROUND

Proanthocyanidins, the most abundant polyphenols in chocolate, are not depolymerized in the stomach and reach the small intestine intact, where they are hardly absorbed because of their high molecular weight. In vitro and in vivo studies using pure compounds as substrates suggest that proanthocyanidins and the related catechin monomers may be degraded into more bioavailable low-molecular-weight phenolic acids by the microflora in the colon.

OBJECTIVE

The aim of the study was to estimate the amounts of phenolic acids formed by the microflora and excreted in the urine of human subjects after consumption of polyphenol-rich chocolate.

DESIGN

After consumption of a polyphenol-free diet for 2 d and a subsequent overnight fast, 11 healthy subjects (7 men and 4 women) consumed 80 g chocolate containing 439 mg proanthocyanidins and 147 mg catechin monomers. All urine was collected during the 24 h before chocolate consumption and at 3, 6, 9, 24, and 48 h after chocolate consumption. Aromatic acids were identified in urine by gas chromatography-mass spectrometry and were quantified by HPLC-electrospray ionization tandem mass spectrometry.

RESULTS

Chocolate intake increased the urinary excretion of the 6 following phenolic acids: m-hydroxyphenylpropionic acid, ferulic acid, 3,4-dihydroxyphenylacetic acid, m-hydroxyphenylacetic acid, vanillic acid, and m-hydroxybenzoic acid.

CONCLUSION

The antioxidant and biological effects of chocolate may be explained not solely by the established absorption of catechin monomers but also by the absorption of microbial phenolic acid metabolites.

Influence of environmental tobacco smoke on vitamin C status in children

BACKGROUND

It is known that vitamin C status is compromised in smokers. The vitamin C status of nonsmokers who are exposed to environmental tobacco smoke (ETS) is now being elucidated.

OBJECTIVE

We assessed vitamin C status in children who were either exposed or not exposed to ETS, and we sought to associate changes in vitamin C status with the amount of ETS exposure.

DESIGN

The study group included 512 children aged 2-12 y; 50% of them were exposed to ETS in the home because their parents smoked. Dietary intake of vitamin C, obtained with a 24-h recall questionnaire, and blood ascorbate concentrations were compared in the exposed and unexposed groups. Smoke exposure was assessed by measuring a biomarker, urinary cotinine. Age, sex, and body mass index were examined as potential correlates of vitamin C status in each exposure category.

RESULTS

Plasma ascorbate concentrations were lower, by 3.2 micro mol/L on average, in ETS-exposed children than in unexposed children who consumed equivalent amounts of vitamin C; this was a highly significant difference (P = 0.002). This reduction in plasma ascorbate occurred even with very low exposure to ETS.

CONCLUSIONS

ETS can reduce concentrations of ascorbate, an important blood antioxidant, even when the amount of smoke exposure is minimal. Children exposed to ETS should be encouraged to consume increased amounts of foods rich in vitamin C or should be given the equivalent amount of this vitamin as a supplement.

Dose-dependent bone-sparing effects of dietary isoflavones in the ovariectomised rat

The dose-dependent bone-sparing effects of dietary isoflavones (IF) were investigated in adult (7-month-old) Wistar rats. Forty animals were ovariectomised, allocated into four groups of ten rats each, and immediately treated orally with IF at 0 (OVX), 20 (IF20), 40 (IF40) or 80 (IF80) microg/g body weight per d for 91 d; ten sham-operated (SH) controls received the same diet without added IF. Animals were killed on day 91. Both femoral failure load and total femoral, diaphyseal or metaphyseal bone mineral densities (BMD) were lower in OVX animals than in SH animals. Urinary deoxypyridinoline (DPD) excretion, a marker of bone resorption, and plasma osteocalcin (OC) levels, a marker of osteoblast activity, were higher in OVX animals than in SH animals. Total femoral and diaphyseal BMD and femoral failure load were similar in IF-treated rats and SH rats. Although metaphyseal BMD in IF40 or IF80 rats was similar to that in SH rats, its value was lower in IF20 rats than in controls. The day 91 urinary DPD excretion in IF40 and IF80 rats, but not in IF20 rats, was similar to that in SH rats. Day 91 plasma OC concentrations in IF-treated rats were similar to day 45 values, but were decreased in OVX and SH rats. Thus, daily IF consumption prevented ovariectomy-induced bone loss, both by depressing bone resorption and stimulating osteoblast activity. Moreover, as only the highest IF level induced a weak uterotrophic activity, the optimal IF dose which preserves both cancellous and cortical bone, but exhibits no oestrogen-like effects on the uterus, was 40 microg/g body weight per d.

The influence of ketoacids on plasma creatinine assays in diabetic ketoacidosis

OBJECTIVE

Analysis of the interference of ketoacids on various routine plasma creatinine assays during a clinical episode of diabetic ketoacidosis (DKA).

DESIGN

Observational study. Blood samples were drawn before, during and after standard in-hospital treatment. Plasma creatinine was measured with two dissimilar enzymatic assays (creatininase PAP + and creatinine iminohydrolase Serapak), a kinetic alkaline picrate method (Jaffé) and a high-performance liquid chromatography (HPLC) procedure. Acetoacetate and beta-hydroxybutyrate were analysed by enzymatic methods.

SETTING

Department of Medicine, University Hospital.

SUBJECTS

Nine patients who experienced 10 episodes of DKA.

MAIN OUTCOME MEASURES

Agreement of the routine plasma creatinine assays with HPLC and analysis of possible interferents.

RESULTS

At presentation, the Jaffé assay gave falsely high values of plasma creatinine (median 99 micromol L(-1)), in contrast to the PAP+ (median 60.5 micromol L(-1)) and HPLC assays (median 67.5 micromol L(-1)). This positive error decreased during treatment. This was due to a decrease in acetoacetate, as the positive error by the Jaffé method correlated with the acetoacetate concentration (r = 0.79, P < 0.0001). In the multiple regression analysis, beta-hydroxybutyrate caused no additional interference by the Jaffé assay, confirmed by in vitro experiments. Analysis of agreement showed that the difference between PAP+ and HPLC creatinine was -4.6 +/- 3.0 micromol L(-1) (mean +/- SD), and 2.0 +/- 5.3 micromol L(-1) between Serapak and HPLC. This was statistically significant, but clinically negligible.

CONCLUSION

Acetoacetate caused severe interference of the alkaline picrate (Jaffé) assay, which might influence therapeutic decisions at the start of diabetic ketoacidosis. Enzymatic assays lack this interference.

Daidzein is more efficient than genistein in preventing ovariectomy-induced bone loss in rats

We investigated the ability of genistein and daidzein, two soybean isoflavones, compared with that of 17 alpha-ethinylestradiol, to prevent bone loss in ovariectomized rats, a model for postmenopausal osteoporosis. Female Wistar rats (n = 65; 12 mo old) were either sham-operated (SH; n = 13) or ovariectomized (OVX; n = 52). On d 0, OVX rats were randomly assigned to groups as follows: 13 received genistein [G; 10 mcg/(g body weight. d)], 13 were treated with daidzein [D; 10 mcg/(g body weight. d)], 13 received 17 alpha-ethinylestradiol [E(2); 30 mcg/kg body weight. d)] and 13 were untreated (OVX). Compounds were mixed with a soy protein-free powdered semipurified diet and given orally for 3 mo. On d 90, the bone mineral density (BMD) in lumbar vertebrae, femur and its metaphyseal and diaphyseal zones (rich in cancellous and cortical bone, respectively) was lower in OVX than in SH (P < 0.01). In D or E(2), the four BMD were not different from SH, whereas in G, only the diaphyseal BMD was not different from SH. Image analysis performed in the distal femur metaphysis revealed that the cancellous bone area was lower in OVX than in SH (P < 0.01). Only the area in D was not different from that in SH. Finally, the bone turnover, which was higher in OVX than in SH (P < 0.005 and P < 0.05 for plasma osteocalcin concentration and urinary deoxypyridinoline excretion, respectively), was not different in G, D or E(2) compared with SH. Therefore, consumption of 17 alpha-ethinylestradiol or daidzein was more efficient than genistein in preventing ovariectomy-induced bone loss in rats.

Influence of the preceding exchange on peritoneal equilibration test results: a prospective study

The standard peritoneal equilibration test (PET) should be performed after a long overnight dwell, which is easily possible in continuous ambulatory peritoneal dialysis patients. However, for such a procedure, patients undergoing automated peritoneal dialysis or daily ambulatory peritoneal dialysis have to change their regimen and, in the case of high peritoneal transport rates, run the risk for fluid absorption. We compared dialysate to plasma ratios (D/P) of creatinine, blood urea nitrogen (BUN), phosphate, sodium, total protein, and albumin measured during PET after an 8- to 11-hour dry period (PET dry), after a preceding exchange with a long dwell time (PET standard), and immediately after tidal peritoneal dialysis (PET tidal). D/P ratios of creatinine, BUN, phosphate, and sodium at 2 and 4 hours were greater during PET dry compared with both PET standard and PET tidal. The quotient of dialysate glucose at 2 hours to dialysate glucose at time point 0 was significantly less in PET dry compared with both PET tidal and PET standard. During the first 2 hours of PET, the increase of D/P curves of creatinine and BUN, as well as phosphate, was significantly steeper in PET dry than PET tidal and PET standard. D/P ratios of albumin and protein were greatest in PET dry and least in PET tidal. There was a significant difference between all three PETs at 0, 2, and 4 hours of dwell time. PET curves were significantly steeper during PET dry compared with PET tidal in case of D/P protein (during the first 2 hours of dwell time) and D/P albumin (during the entire dwell time). Similar differences between the PET curves of protein and albumin were observed between PET dry and PET standard. These data clearly indicate a dry period before PET significantly influences the D/P ratios of small solutes, protein, and albumin measured during the test.

Peritoneal dialysis adequacy: a model to assess feasibility with various modalities

BACKGROUND

The current standard of adequacy for peritoneal dialysis (PD) is to provide a weekly normalized urea clearance (Kt/V) of 2.0 or more and a creatinine clearance (CCr) of 60 liter/1.73 m2 or more. As native renal function is lost, it is important to determine the effectiveness of the available therapeutic modalities in achieving these goals.

METHODS

A model to assess our ability to provide a weekly Kt/Vurea of 2.0 or more and a CCr of 60 liter/1.73 m2 or more to anuric patients undergoing continuous ambulatory PD (CAPD) and automated PD (PD Plus) was developed. The body surface area (BSA) distribution was obtained from 38,768 patients undergoing dialysis during January 1997. The distribution of peritoneal transport rates (PTRs) was obtained from 2531 peritoneal equilibration tests performed during 1996. The weekly Kpt/Vurea was calculated for the various PTR groups and the range of BSA with four PD prescriptions: CAPD 8 liters, CAPD 10 liters, PD Plus 12 liters, and PD Plus 15 liters, using a previously validated kinetic program (PackPD).

RESULTS

The predicted percentage of patients capable of achieving the adequacy goals for Kt/V and CCr, respectively, were 24.8 and 11. 2 for CAPD 8 liters, 54.2 and 33.0 for CAPD 10 liters, 77.8 and 54.9 for PD Plus 12 liters, and 93.2 and 72.9 for PD Plus 15 liters.

CONCLUSIONS

Most patients can attain the current adequacy standards of therapy with automated PD, but few (less than 25%) can do so with standard CAPD in the absence of residual renal function.