Circadian rhythm in urinary N-acetyl-beta-glucosaminidase (NAG) of clinically healthy subjects. Timing and phase relation to other urinary circadian rhythms

Intraindividual variations of urinary biomarkers in hospitalized children with glomerular diseases: a prospective observational study

This study aimed to assess the intraindividual variations of urinary biomarkers in hospitalized children with glomerular diseases. Hospitalized children with glomerular diseases participated in the study. For each patient, an overnight (9:00 p.m.-7:00 a.m.) urine was collected, followed by a 24-h urine (classified into four distinct periods: morning 7:00 a.m.-12:00 p.m., afternoon 12:00 p.m.-4:00 p.m., evening 4:00 p.m.-9:00 p.m., and overnight 9:00 p.m.-7:00 a.m.). The concentrations of protein, albumin, N-acetyl-beta-D-glucosaminidase, and epidermal growth factor (EGF) were measured and normalized by three correction factors (creatinine, osmolality, or specific gravity, respectively). Additionally, the 2nd overnight urine sample was grouped into different aliquots according to centrifugation, additives, storage temperature, or delayed processing. Twenty (14 boys, 6 girls) children were enrolled, with an average age of 11.3 years. Among the three correction factors, creatinine-normalized biomarkers provided the best agreements among different periods over 24 h. There were significant diurnal variations during 24 h in the concentrations of urinary protein, albumin, N-acetyl-beta-D-glucosaminidase, and EGF (p = 0.001, p = 0.003, p = 0.003, and p = 0.003, respectively). Evening urine overestimated 24-h urinary protein and albumin, while overnight urine underestimated 24-h urinary albumin. Urinary EGF showed low variability within a day or between the 2 days (coefficients of variation 10.2% and 10.6%, respectively) and excellent agreements (intraclass correlation coefficients > 0.9) with 24-h urinary concentration. Furthermore, urinary EGF was not affected by centrifugation, additives, storage temperature, or delayed processing of urine samples (all p > 0.05).  Conclusion: Given the diurnal variations of urinary biomarkers, urine samples should be collected during the same time period in clinical practice if possible. The results also extend the evidence for urinary EGF as a relatively stable biomarker applied in the future clinical practice. What is Known: • Urinary biomarkers have been widely used or discussed in making diagnoses and therapy regimens and estimating the prognosis of pediatric glomerular diseases. It remains unclear whether their levels would be affected by the time of sample collection, processing methods, and storage conditions in hospitalized children with glomerular diseases. What is New: • The levels of both commonly used biomarkers and novel biomarkers exhibited diurnal variations in hospitalized children with glomerular diseases. • Our results extend the evidence for urinary EGF as a relatively stable biomarker applied in the future clinical practice.

Telemonitored Human Circadian Temperature Dynamics During Daily Routine

BACKGROUND

Circadian rhythms in body temperature coordinate peripheral molecular clocks, hence they could potentially predict optimal treatment timing (chronotherapy) in individual patients. Circadian parameters in chest surface body temperature (Chesttemp) were recorded remotely and in real time through the use of wearable sensors.

METHODS

The dynamics of circadian oscillations in Chesttemp and core body temperature (Coretemp) and their moderation by sex and age were analysed in 38 men and 50 women, aged 21-78 years. In two studies (ST1 and ST2), Chesttemp was measured every minute and teletransmitted using a BLE-connected sensor for 3.6-28.3 days. Additionally, in ST2, Coretemp was recorded per minute in 33 age- and sex-stratified subjects using electronic ingestible pills with radio-frequency transmissions. Circadian parameters were computed using spectral analysis and cosinor modelling. The temporal relations between Chesttemp and Coretemp cosinor parameters were summarised with principal component (PC) analysis. The effect of sex and age was analysed through multivariate regression.

RESULTS

Using spectral analysis, a dominant period of 24- or 12-h was identified in 93.2% of the Chesttemp and in 100% of the Coretemp time series. The circadian parameters varied largely between-subjects both for Chesttemp (ranges: mesors, 33.2-36.6°C; amplitudes, 0.2-2.5°C; acrophases, 14:05-7:40), and Coretemp (mesors, 36.6-37.5°C; amplitudes, 0.2-0.7°C; bathyphases, 23:50-6:50). Higher PC loadings mainly corresponded to (i) large Chesttemp amplitudes, and phase advance of both temperature rhythms for the first PC (PC1, 27.2% of variance var.), (ii) high mesors in both temperature rhythms for PC2 (22.4% var.), and (iii) large Coretemp amplitudes for PC3 (12.9% var.). Chesttemp and Coretemp mesors and PC2 loadings decreased in females, while remaining quite stable in males as a function of age. In contrast, Coretemp amplitude and PC3 loadings increased with age in females, but decreased in males. Finally, older subjects, both female and male, displayed a reduction in ultradian variabilities, and an increase in both Chesttemp circadian amplitude and PC1 loadings.

INTERPRETATION

The dynamics relations between Chesttemp and Coretemp rhythms were largely moderated by age and sex, with results suggesting that treatment timing could be most critical for therapeutic index in women and in order people.

Perspectives on the relevance of the circadian time structure to workplace threshold limit values and employee biological monitoring

The circadian time structure (CTS) and its disruption by rotating and nightshift schedules relative to work performance, accident risk, and health/wellbeing have long been areas of occupational medicine research. Yet, there has been little exploration of the relevance of the CTS to setting short-term, time-weighted, and ceiling threshold limit values (TLVs); conducting employee biological monitoring (BM); and establishing normative reference biological exposure indices (BEIs). Numerous publications during the past six decades document the CTS substantially affects the disposition - absorption, distribution, metabolism, and elimination - and effects of medications. Additionally, laboratory animal and human studies verify the tolerance to chemical, biological (contagious), and physical agents can differ extensively according to the circadian time of exposure. Because of slow and usually incomplete CTS adjustment by rotating and permanent nightshift workers, occupational chemical and other contaminant encounters occur during a different circadian stage than for dayshift workers. Thus, the intended protection of some TLVs when working the nightshift compared to dayshift might be insufficient, especially in high-risk settings. The CTS is germane to employee BM in that large-amplitude predictable-in-time 24h variation can occur in the concentration of urine, blood, and saliva of monitored chemical contaminants and their metabolites plus biomarkers indicative of adverse xenobiotic exposure. The concept of biological time-qualified (for rhythms) reference values, currently of interest to clinical laboratory pathology practice, is seemingly applicable to industrial medicine as circadian time and workshift-specific BEIs to improve surveillance of night workers, in particular. Furthermore, BM as serial assessments performed frequently both during and off work, exemplified by employee self-measurement of lung function using a small portable peak expiratory flow meter, can easily identify intolerance before induction of pathology.

IL-18 and urinary NGAL predict dialysis and graft recovery after kidney transplantation

Current methods for predicting graft recovery after kidney transplantation are not reliable. We performed a prospective, multicenter, observational cohort study of deceased-donor kidney transplant patients to evaluate urinary neutrophil gelatinase-associated lipocalin (NGAL), IL-18, and kidney injury molecule-1 (KIM-1) as biomarkers for predicting dialysis within 1 wk of transplant and subsequent graft recovery. We collected serial urine samples for 3 d after transplant and analyzed levels of these putative biomarkers. We classified graft recovery as delayed graft function (DGF), slow graft function (SGF), or immediate graft function (IGF). Of the 91 patients in the cohort, 34 had DGF, 33 had SGF, and 24 had IGF. Median NGAL and IL-18 levels, but not KIM-1 levels, were statistically different among these three groups at all time points. ROC curve analysis suggested that the abilities of NGAL or IL-18 to predict dialysis within 1 wk were moderately accurate when measured on the first postoperative day, whereas the fall in serum creatinine (Scr) was not predictive. In multivariate analysis, elevated levels of NGAL or IL-18 predicted the need for dialysis after adjusting for recipient and donor age, cold ischemia time, urine output, and Scr. NGAL and IL-18 quantiles also predicted graft recovery up to 3 mo later. In summary, urinary NGAL and IL-18 are early, noninvasive, accurate predictors of both the need for dialysis within the first week of kidney transplantation and 3-mo recovery of graft function.

The influence of urinary flow rate in children on excretion of markers used for assessment of renal damage: albumin, gamma-glutamyl transpeptidase, N-acetyl-beta-D -glucosaminidase, and alpha1-microglobulin

The aim of the present study was to examine the influence of urinary flow rate on markers of renal function in children. A sub-study of the New England Children's Amalgam Trial collected 82 pairs of urine samples from children aged 10-16 years: a timed overnight collection and a spot daytime sample collected the following day. These samples were analyzed for albumin, gamma-glutamyl transpeptidase (gamma-GT), N-acetyl-beta-D-glucosaminidase (NAG), alpha1-microglobulin (A1M), and creatinine concentration. Regression analysis was used to model the effect of urinary flow rate in the timed overnight samples. A paired t-test compared concentrations and creatinine-corrected renal markers between overnight and daytime samples. Albumin, gamma-GT, NAG, and A1M excretion rates increased significantly with urinary flow rate. Their corresponding creatinine-corrected markers did not vary significantly with urinary flow rate, but the creatinine-corrected excretions of albumin, gamma-GT, and NAG were significantly higher in daytime samples than in overnight samples, with the same (non-significant) trend for A1M. The influence of urinary flow rate on creatinine-corrected markers of renal function was markedly less than its influence on excretion rates. Therefore, the use of creatinine-corrected markers seems to be a good choice in practice, with the caveat that daytime and overnight samples are not comparable.

The effect of age, sex, and race on urinary markers of kidney damage in children

BACKGROUND

The aim of this study is to examine the effects of age, sex, and race on the excretion and concentrations of albumin, gamma-glutamyl transpeptidase (gamma-GT), N-acetyl-beta-d-glucosaminidase (NAG), alpha(1)-microglobulin (alpha1M), and creatinine in children.

STUDY DESIGN

Secondary analysis of a clinical trial, The New England Children's Amalgam Trial, which examined effects of amalgam dental fillings.

SETTING & PARTICIPANTS

534 children aged 6 to 10 years at baseline were recruited from Boston, MA, and rural Maine.

PREDICTORS

Age, sex, and race.

OUTCOMES & MEASUREMENTS

Urine samples were collected annually for 5 years and analyzed for creatinine, albumin, gamma-GT, NAG, and alpha1M concentrations. Repeated-measures analysis of covariance was used to model effects of age, sex, and race on these values, as well as calculated excretion rates.

RESULTS

All measures of creatinine and gamma-GT increased significantly with age. Albumin and gamma-GT concentration and excretion (milligrams per gram of creatinine or units per gram creatinine) were significantly greater for girls compared with boys. alpha1M concentration and creatinine excretion were greater for boys compared with girls. Creatinine concentration was significantly greater for blacks than for whites and Hispanics. Creatinine excretion and all gamma-GT levels were significantly greater for blacks and Hispanics compared with non-Hispanic whites.

LIMITATIONS

The study population, recruited for a clinical trial, was of lower socioeconomic status than the general population. The high limit of detection for alpha1M resulted in a majority of samples less than the detection limit.

CONCLUSIONS

We recommend considering age, sex, and race in the interpretation of urinary markers. It also is recommended that epidemiological studies and clinical trials account for age, sex, and race in statistical models comparing urinary markers of kidney damage.

Calcitonin stimulates lysosomal enzyme release and uptake in LLC-PK1 cells

Renal tubular targeted hormones increase urinary excretion of a lysosomal enzyme, N-acetyl-beta-D-glucosaminidase (NAG). To elucidate the mechanism of this event, the calcitonin effect on NAG handling by LLC-PK1 cells was examined. Calcitonin (1 nM to 1 microM), phorbol myristate (10 nM to 1 microM), and ionomycin (1 to 10 microM) promoted NAG release without any increase in lactate dehydrogenase release or any reduction of mitochondrial dehydrogenase activity. Treatment with 100 nM calphostin C or 50 microM KN-93 partially reversed the calcitonin effect on NAG release. Calcitonin promoted secretion of fluorescence ceramide, a reporter of protein transport from Golgi apparatus to cell surface. Calcitonin-stimulated NAG release was partially inhibited by 10 microg/ml brefeldin A, a blocker of protein transport through the Golgi apparatus. Calcitonin accelerated cellular uptake of exogenous NAG, which was inhibited by low temperature, 0.1 mM monodansyl cadaverine (receptor-mediated endocytosis inhibitor), and 10 mM mannose-6-phosphate. Furthermore, calcitonin promoted progression of intracellular membranes stained by a fluorescence membrane marker, styryl pyridinium dye, from cell periphery to perinuclear regions (commonly referred to as recycling vesicles) and increased dye release from preloaded cells. Fluorescence release from the cells pre-loaded with FITC-labeled NAG or albumin was also stimulated by calcitonin. These calcitonin effects on endocytotic and re-exocytotic pathways were inhibited by 100 nM cytochalasin D, 100 nM nocodazole, 0.1 to 1 microM bafilomycin A1, or 0.1 mM monodansyl cadaverine. Increased urinary NAG excretion has been considered to reflect renal tubular damage. However, it was demonstrated here that stimulation of secretory and recycling pathways may be an alternative mechanism for calcitonin-induced enzymuria, which will become a new indicator of renal tubular response to this hormone.

Choice of time for urine collection for detecting early kidney abnormalities in hypertensives

The aim of this study was to determine the most appropriate urine collection for detecting differences in the excretion rates of albumin, gamma glutamyl transpeptidase (GGT) and N-acetyl-beta-D-glucosaminidase (NAGA) between normotensive subjects and hypertensive patients on treatment. Twenty treated hypertensive patients, mean (SEM, standard error of mean) age; 52.2 (6.2) years and 20 normotensive subjects, mean age 49.2 (4.2) years, were studied in a consecutive sampling design. Urinary excretion rates of albumin, GGT and NAGA were determined in consecutive timed urine samples collected overnight and during 3-5 h the next morning. Mean (SEM) overnight excretion rates for albumin, GGT and NAGA for normotensive subjects were 11.05 (1.18) micrograms/min, 17.00 (2.20) mU/min and 6.55 (0.39) mU/min, respectively, which were significantly lower than those of hypertensive subjects which were 20.77 (2.14) micrograms/min, 21.84 (1.65) mU/min and 10.92 (0.87) mU/min, respectively (P < 0.05). The mean (SEM) percentage increases in urinary albumin, GGT and NAGA in morning urine collections of normotensive subjects of 15.22 (3.88)%, 34.04 (6.45)% and 11.54 (3.63)%, respectively were significantly lower than 107.03 (15.04)%, 121.96 (16.71)% and 72.75 (7.50)% found in hypertensive patients (P < 0.05). These data suggest that were urinary albumin and tubular enzyme excretion to be used as correlates of hypertensive renal damage, ambulatory urine collections may be more sensitive than overnight collections.

NAG, GGT, creatinine, urea and creatinine clearance before and after ESWL

N-acetyl-beta glucosaminidase (NAG) and gamma-glutamyltransferase (GGT) were measured in the urine and serum before, 24 hours and one week after extracorporeal shock wave lithotripsy in 25 patients. Although ESWL is the preferred method in the treatment of kidney stones, its effect on renal parenchymal cells has not been sufficiently elucidated. Since radiographic methods remain inadequate in the estimation and management of parenchymal damage, it is useful to establish the specific renal cell proteins in urine and serum, reflecting renal tubular cell destruction.

A lack of coordination in the release of urinary lysosomal and brush border enzymes following renovascular surgery

The urinary secretion of two lysosomal enzymes, N-acetyl-D-glucosaminidase (NAG, EC 3.2.1.30) and beta-glucuronidase (GLR, EC 3.2.1.31), and two brush border enzymes, alanine aminopeptidase (AAP, EC 3.4.11.2) and gamma-glutamyltransferase (GGT, EC 2.3.2.2), was examined in apparently healthy individuals and in patients before and after renovascular surgery for treatment of hypertension. Eight out of nine patients had elevated levels of at least one enzyme before surgery. The ranking in their frequency of elevation was NAG greater than AAP greater than GLR greater than GGT. In comparing the release of any two enzymes in apparently healthy individuals, the release was coordinated except for GGT and GLR. In individual patients following surgery the excretion of the lysosomal enzymes was highly coordinated whereas the release of the brush border enzymes was less coordinated. Comparisons of lysosomal to brush border enzyme activities revealed dissimilar release patterns between these two classes of enzymes. Analysis of variance over the entire hospitalization period showed that NAG/GLR (p = 0.42) and AAP/GGT (p = 0.12) did not vary significantly whereas all comparisons of lysosomal to brush border enzymes varied significantly (p less than or equal to 0.03). These results indicate that enzymes derived from different subcellular organelles, lysosomes or brush borders, have similar release patterns. However, the lack of a significant correlation between lysosomal and brush border enzyme excretion implies that the two processes are not interdependent. These studies further suggest that the transient pathophysiological changes that occur within renal cells following renovascular surgery affect these cellular components in different ways.

Excretion of urinary N-acetyl-beta-D-glucosaminidase isoenzymes after renal transplantation in the rat

The urinary excretion of N-acetyl-beta-D-glucosaminidase isoenzymes A and B following kidney transplantation was studied in rats. High enzymuria with permanent marked isoenzyme B excretion occurred from the immediate post-operative period to the irreversible rejection episode. Isoenzyme B could represent as much as 10-40% of total N-acetyl-beta-D-glucosaminidase activity and it reflected the intensity of tubular lesions as observed by histological examination of allograft specimens. Thus, N-acetyl-beta-D-glucosaminidase B isoenzyme determination may reinforce the diagnostic value of total (A + B) urinary N-acetyl-beta-D-glucosaminidase activity determination during the various complications which can occur after transplantation.

Circadian rhythm in gamma glutamyltranspeptidase and leucine aminopeptidase urinary activity in rats

Urinary gamma glutamyltranspeptidase (GGT) and leucine aminopeptidase (LAP), renal tubular brush border enzymes, have been shown to be sensitive indicators of renal tubular functions. This study documents circadian rhythms in the urinary activity of GGT and LAP, statistically validated and quantified by the cosinor method, in 15 male Wistar rats standardized to a LD 12:12 illumination schedule (light from 0800 hr to 2000 hr) and fed ad libitum. The acrophase of the circadian rhythms in urinary GGT and LAP activity occurred at the end of the rest span of the animals: between 1730 and 1915 for GGT (depending on the mode of expression of the activity) and between 1700 and 1910 for LAP. Of striking resemblance in their timing, both these rhythms were also of large amplitude (about 50% of the mesor for urinary GGT activity and about 45% for LAP one). The circadian acrophases of urinary GGT and LAP activity led in timing the circadian rhythms in urine volume and creatinine excretion by about 13 hr. Such findings consistent with the circadian variations found by other investigators in GGT in kidney homogenates or in LAP in human urine thus reflect a periodicity in renal tubular function. The reasons for these circadian variations, still unknown at this time, are discussed. The influence recently demonstrated of the hormonal context on protein and enzyme synthesis at the tubule, and its phase relations to urinary enzyme excretion emphasize how much the circadian rhythm in urinary GGT and LAP activity is well included in the murine time structure.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibition of A and B N-acetyl-beta-D-glucosaminidase urinary isoenzymes by urea

A urinary fraction which inhibits the activity of N-acetyl-beta-D-glucosaminidase (NAG) has been isolated and identified as being urea. Usually present in high concentration, urea appears to be the only urinary component responsible for the frequently observed urinary NAG inhibition. The inhibition of the two urinary NAG isoenzymes A and B is competitive with respective Ki values of about 70 mmol/l and 60 mmol/l. With routine assay conditions, it seems that a dilution of urine prior to enzyme assay is sufficient to abolish the inhibition of the two isoenzymes A and B by endogenous urea.

Enzymuria of the rat: biorhythms and sex differences

Alanine aminopeptidase, gamma-glutamyltransferase and N-acetyl-beta-D-glucosaminidase were measured daily over 65 days in 24-hour urine of male and female Wistar rats. The mathematical evaluation was based on the Fourier-analysis. The excretion of alanine aminopeptidase and gamma-glutamyltransferase was higher in male than in female rats. This sex-dependent difference was not observed for N-acetyl-beta-D-glucosaminidase. The excretion of the 3 enzymes followed a biorhythm with a dominant period of 7 days for gamma-glutamyltransferase and N-acetyl-beta-D-glucosaminidase and one of 9 days for alanine aminopeptidase. Biorhythms and sex differences of enzymuria should be considered in experimental designs.

Specimen collection time for enzyme analysis in urine

Catalytic activity of N-acetyl-beta-D-glucosaminidase, alanine aminopeptidase, lactate dehydrogenase, isoenzyme 1 of lactate dehydrogenase, lysozyme, gamma-glutamyl transferase and alkaline phosphatase in urine specimens collected between 6 a.m. and 9 a.m. were determined in 25 patients with acute renal failure. We found no statistical differences (Wilcoxon's t test) between specimens collected at 6 a.m. and 9 a.m. We conclude that, in renal patients, the first morning specimen (overnight urine) may be used for enzyme analysis.

Circadian-stage dependence of methotrexate in a keratinized epithelium. An in-vivo study using flow cytometry on the hamster cheek pouch epithelium

The partially synchronized cell system of the hamster cheek pouch epithelium shows a characteristic diurnal rhythm of cell proliferation. Bolus injections of methotrexate (Mtx) in both lethal (10 g/m2) and non-lethal (2 g/m2) doses were found to inhibit cell-cycle progression primarily by impairing the G1/S transition. The results were obtained by flow cytometric DNA analysis. The inhibitory effect of Mtx manifested itself as a relative decrease of the S fraction (drug-effector phase), and was found to be dependent both on the dose and on the time of the day it was given. A bolus injection of Mtx was given either at 1200 hr (when a minimal number of cells are in S phase) or at 0200 hr (when a maximum number of cells are in S phase). The greatest cumulative decrease in S fraction was seen when the injection was given at 1200 hr. The time between injection and the effect (seen as a decrease in S fraction) was independent of the time of the Mtx injection, but seemed instead to be related to the natural diurnal period of increasing flux from G1 to S phase (at the onset of the dark period). The main effect (the relative decrease in S fraction) was repeated during the following 24-hr period, pointing to a protracted effect of Mtx on G1 cells. G1 cells affected by the initial high Mtx plasma concentration seem to be responsible for the reduced influx into S phase in both the first and second 24-hr period. In earlier toxicological studies, the survival rate of hamsters was dependent on the time of injection and was highest after injection at 1200 hr. Thus maximum cytokinetic effect on epithelial cells was found at the time of the day when there was a minimum lethal effect on the animal.

Increased serum and urinary N-acetyl-beta-D-glucosaminidase activity in human hypertension: early indicator of renal dysfunction

The pathophysiologic significance of increased serum and urinary N-acetyl-beta-D-glucosaminidase (NAG) activity in hypertension was investigated. The subjects were 32 male patients, aged 40-65 years, with mild or borderline, uncomplicated hypertension and 26 age-matched, male normotensive volunteers. Compared to values in control subjects, NAG activity in the serum, spot and 24-hour urine samples of hypertensive subjects was increased (p less than 0.01). Serum NAG activity in hypertensive subjects was inversely correlated with glomerular filtration rate (r = -0.49, p less than 0.01, N = 31) and renal plasma flow (r = -0.56, p less than 0.02, N = 19) and positively correlated with mean arterial blood pressure (r = 0.40, p less than 0.05). The elevation of serum NAG activity in hypertension is a biochemical marker of the reduction in glomerular filtration rate and renal plasma flow.