Characterization and structural study of a novel ß-N-acetylgalactosaminidase from Niabella aurantiaca.

We report here the identification, characterization and three-dimensional (3D) structure determination of NaNga, a newly identified ß-N-acetylgalactosaminidase from the Gram-negative soil bacterium Niabella aurantiaca DSM 17617. When recombinantly expressed in Escherichia coli, the enzyme selectively cleaved 4-nitrophenyl-N-acetyl-ß-d-galactosamine (pNP-ß-d-GalpNAc). The X-ray crystal structure of the protein was refined to 2.5 Å and consists of an N-terminal ß-sandwich domain and a (ß/α)8 barrel catalytic domain. Despite a mere 22% sequence identity, the 3D structure of NaNga is similar to those previously determined for family GH123 members, suggesting it also employs the same substrate-assisted catalytic mechanism. Inhibition by N-acetyl-galactosamine thiazoline (GalNAc-thiazoline) supports the suggested mechanism. A phylogenetic analysis of its proximal sequence space shows significant clustering of unknown sequences around NaNga with sufficient divergence with previously identified GH123 members to subdivide this family into distinct subfamilies. Although the actual biological substrate of our enzyme remains unknown, examination of the active site pocket suggests that it may be a ß-N-acetylgalactosaminide substituted by a monosaccharide at O-3. Analysis of the genomic context suggests, in turn, that this substituted ß-N-acetylgalactosaminide may be appended to a d-arabinan from an environmental Actinomycete.

Novel Urinary Biomarkers for Diagnosis of Acute Pyelonephritis in Children.

Urinary tract infection (UTI) is common among pediatric population. Pyelonephritis, especially in young infants, is associated with a significant morbidity. Usually, clinical manifestations, laboratory findings, and imaging are used to differentiate between lower and upper UTI. Lack of specific clinical findings and commonly used nonspecific blood indices are important hamper differentiation between lower and upper UTI in early stages. Imaging techniques are neither cost benefit nor safe for detection of UTI. Recent efforts have focused on characterization of novel serum and urinary biomarkers for early detection of acute pyelonephritis in children. It seems that urinary NGAL, NAG, TNF-α and IL-8 may be used as novel markers for early diagnosis of acute pyelonephritis in children.

New biomarkers defining a novel early stage of Fabry nephropathy: A diagnostic test study.

BACKGROUND: Renal involvement in Fabry disease is a major determinant of overall disease prognosis and early enzyme replacement therapy seems effective in preventing progression of kidney injury. Gb3 storage, glomerular sclerosis and tubulo-interstitial fibrosis may occur with minimal or no changes on standard renal tests, hence alternative markers of renal dysfunction are crucial. In this study we compared several biomarkers with albuminuria in the identification of incipient Fabry nephropathy and their diagnostic accuracy to identify chronic kidney disease (CKD) stage≥2. METHODS: In this multicentre, prospective, cross-sectional and diagnostic test study, a cohort of 78 Fabry patients and 25 healthy controls was consecutively recruited. Patients were grouped by severity of nephropathy: 1) albuminuria<30mg/g; 2) albuminuria 30-299mg/g; 3) albuminuria>300mg/g; 4) glomerular filtration rate (GFR)<60mL/min/1.73m2. Several index tests, namely biomarkers of glomerular (transferrin and type IV collagen) and tubular (α1-microglobulin, N-acetyl-ß-glucosaminidase and alanine aminopeptidase) dysfunction were compared with the reference standard (albuminuria). RESULTS: Significant increase of all tested biomarkers in Fabry patients, even in the subgroup of patients without evidence of nephropathy. We also found inverse significant correlations between estimated GFR and collagen type IV (ρ=-0.289; p=0.003) or N-acetyl-ß-glucosaminidase (ρ=-0.448; p<0.001), which were stronger than with albumin (ρ=-0.274; p=0.019). There was also better diagnostic accuracy of N-acetyl-ß-glucosaminidase to predict CKD stage≥2. CONCLUSIONS: These results suggest that studied biomarkers may overcome the limitations of albuminuria as sensitive marker of early renal dysfunction and as marker for CKD progression risk. These biomarkers may also define novel early stages of nephropathy characterized by mesangial expansion and/or tubular damage.

Biomarkers of Heart Failure with Preserved and Reduced Ejection Fraction.

Biomarkers are increaingly being used in the management of heart failure not only for the purpose of screening, diagnosis, and risk stratification, but also as a guide to evaluate the response to treatment in the individual patient and as an entry criterion and/or a surrogate marker of efficacy in clinical trials testing novel drugs. In this chapter, we review the role of established biomarkers for heart failure management, according to the main classification of HF phenotypes, based on the measurement of left ventricular ejection fraction, including heart failure with reduced (<40%), preserved (≥50%), and, as recently proposed, mid-range (40-49%) ejection fraction.

Structural and mechanistic insights into a Bacteroides vulgatus retaining N-acetyl-ß-galactosaminidase that uses neighbouring group participation.

Bacteroides vulgatus is a member of the human microbiota whose abundance is increased in patients with Crohn's disease. We show that a B. vulgatus glycoside hydrolase from the carbohydrate active enzyme family GH123, BvGH123, is an N-acetyl-ß-galactosaminidase that acts with retention of stereochemistry, and, through a 3-D structure in complex with Gal-thiazoline, provide evidence in support of a neighbouring group participation mechanism.

The Details of Glycolipid Glycan Hydrolysis by the Structural Analysis of a Family 123 Glycoside Hydrolase from Clostridium perfringens.

Clostridium perfringens is an opportunistic pathogen of humans and animals whose genome encodes a wide variety of putative carbohydrate-hydrolyzing enzymes that are increasingly being shown to be directed toward the cleavage of host glycans. Among these putative enzymes is a member of glycoside hydrolase family 123. Here we show that the recombinant enzyme (referred to as CpNga123) encoded by the gene cloned from C. perfringens strain ATCC 13124 (locus tag CPF_1473) is a ß-N-acetylgalactosaminidase, similar to NgaP from Paenibacillus sp. TS12. Like NgaP, CpNga123 was able to cleave the terminal ß-D-GalNAc-(1→4)-D-Gal and ß-D-GalNAc-(1→3)-D-Gal motifs that would be found in glycosphigolipids. The X-ray crystal structure of CpNga123 revealed it to have an N-terminal ß-sandwich domain and a (ß/α)8-barrel catalytic domain with a C-terminal α-helical elaboration. The structures determined in complex with reaction products provide details of the -1 subsite architecture, catalytic residues, and a structural change in the active site that is likely required to enable hydrolysis of the glycosidic bond by promoting engagement of the substrate by the catalytic residues. The features of the active site support the likelihood of a substrate-assisted catalytic mechanism for this enzyme. The structures of an inactive mutant of CpNga123 in complex with intact GA2 and Gb4 glycosphingolipid motifs reveal insight into aglycon recognition and suggest that the kinked or pleated conformation of GA2 caused by the ß-1,4-linkage between N-acetylgalactosamine and galactose, and the accommodation of this conformation by the enzyme active site, may be responsible for greater activity on GA2.

Renal tubular dysfunction increases mortality in the Japanese general population living in cadmium non-polluted areas.

The aim of this study was to establish the cause-effect relationship between renal tubular dysfunction and mortality. A 19-year cohort study was conducted in 900 men and 1313 women in 1993 or 1994 who lived in two cadmium non-polluted areas in Japan. Hazard ratio (HR) and 95% confidence interval (95% CI) of urinary ß2-microglobulin (ß2-MG) and N-acetyl-ß-glucosaminidase (NAG) for mortality were calculated using a proportional hazard regression. Forward stepwise model selection was applied to the potential covariates such as age, body mass index, mean arterial pressure, various lifestyle factors and present illness. Simultaneously, the dose-effect relationship between renal tubular markers and urinary cadmium at baseline was evaluated using multiple regression analyses. In men, HR was significant for ß2-MG (HR corresponding to an increase of 100 µg/g cre: 1.02) and NAG (HR corresponding to an increase of 1 IU/g cre: 1.05). In women, a significant HR was observed for ß2-MG (HR corresponding to an increase of 100 µg/g cre: 1.01) and NAG (HR corresponding to an increase of 1 IU/g cre: 1.02). Dose-effect relationships were significant for urinary cadmium and all renal tubular markers in men and women. The present study indicated that renal tubular dysfunction was significantly related to mortality in the general population of cadmium non-polluted areas in Japan.

Acute kidney injury induced by aristolochic acid in patients with primary glomerular nephritis.

BACKGROUND: Acute kidney injury induced by aristolochic acid (AA) might occur in patients with chronic glomerular nephritis (CGN). In this study, the clinical and pathological features of patients with acute aristolochic acid nephropathy (AAN) superimposing CGN (AAN-CGN) were investigated. METHODS: Eighteen patients diagnosed as acute AAN were included in this retrospective study, from January 2001 to December 2009. According to the pre-existing CGN, 13 patients were identified as the AAN-CGN group, and 5 isolated AAN patients as the control group. Clinical and pathological features were compared between the two groups. RESULTS: In the AAN-CGN group, six patients complained with gastrointestinal symptoms, such as nausea, vomiting, or loss of appetite. The rest of seven cases were asymptomatic or minimally uncomfortable, who were found with elevated serum creatinine (Scr) in the follow up of CGN. Compared with the control group, the patients in AAN-CGN group had higher levels of serum uric acid, urine n-acetyl-ß-d-glucosaminidase, and urine protein excretion (366.2 ± 122.8 vs. 218.0 ± 125.8 µmol/L, p = 0.037; 9.74 ± 4.4 vs. 1.38 ± 1.01 g/d, p = 0.001; 61.2 ± 21.9 vs. 27.4 ± 15.8 µ/g c cr, p = 0.007, respectively). In addition to, the AAN-CGN patients had an absolutely prominent percentage of macromolecule substance in the urine protein electrophoresis (25.0 ± 6.32 vs. 15.8 ± 7.8%, p = 0.029). The occurrence of hypokalemia and excretion of aminoaciduria were lower than that in the control group. Pathologically, 84.6% of patients were found with tubular brush border dropping, 30.8% with naked tubular basement membrane, and 15.4% with different stages of vascular lesion. There were no statistical differences in the above-mentioned pathological parameters between the two groups. In the follow-up, 10 patients with AAN-CGN recovered with normal Scr, accounting for 76.9%, which was better than the recovery in the control group. CONCLUSION: Patients with acute AAN-CGN manifested with a great mass of urine protein excretion, low incidence of hypokalemia and aminoaciduria, however, the tubular-interstitial lesions were similar to the isolated AAN.

Microdiversity of extracellular enzyme genes among sequenced prokaryotic genomes.

Understanding the relationship between prokaryotic traits and phylogeny is important for predicting and modeling ecological processes. Microbial extracellular enzymes have a pivotal role in nutrient cycling and the decomposition of organic matter, yet little is known about the phylogenetic distribution of genes encoding these enzymes. In this study, we analyzed 3058 annotated prokaryotic genomes to determine which taxa have the genetic potential to produce alkaline phosphatase, chitinase and ß-N-acetyl-glucosaminidase enzymes. We then evaluated the relationship between the genetic potential for enzyme production and 16S rRNA phylogeny using the consenTRAIT algorithm, which calculated the phylogenetic depth and corresponding 16S rRNA sequence identity of clades of potential enzyme producers. Nearly half (49.2%) of the genomes analyzed were found to be capable of extracellular enzyme production, and these were non-randomly distributed across most prokaryotic phyla. On average, clades of potential enzyme-producing organisms had a maximum phylogenetic depth of 0.008004-0.009780, though individual clades varied broadly in both size and depth. These values correspond to a minimum 16S rRNA sequence identity of 98.04-98.40%. The distribution pattern we found is an indication of microdiversity, the occurrence of ecologically or physiologically distinct populations within phylogenetically related groups. Additionally, we found positive correlations among the genes encoding different extracellular enzymes. Our results suggest that the capacity to produce extracellular enzymes varies at relatively fine-scale phylogenetic resolution. This variation is consistent with other traits that require a small number of genes and provides insight into the relationship between taxonomy and traits that may be useful for predicting ecological function.

Lymphocytic enzymes and lipid peroxidation in patients with metabolic syndrome.

OBJECTIVES: Metabolic syndrome (MetS) is considered a state of chronic inflammation. This study aimed to ascertain selected parameters of purinergic and cholinergic systems related to glucose metabolism and inflammation, as well as (γ)-glutamyltransferase (GGT) and N-acetyl-b-glucosaminidase (NAG) activities and lipoperoxidation in lymphocytes of patients with MetS. DESIGN AND METHODS: The adenosine deaminase (ADA), dipeptidyl peptidase IV (DPP-IV), acetylcholinesterase (AChE), GGT and NAG activities, as well as thiobarbituric acid reactive substances (TBARS) levels were investigated in lymphocytes of patients with MetS (n=38) and healthy volunteers (n=41). We also evaluated the insulin levels, anthropometric measurements and routine biochemical analyses. RESULTS: ADA (p<0.05), DPP-IV and AChE (p<0.0001) activities were higher in patients with MetS when compared to the control group. Furthermore, we observed correlations between ADA and DPP-IV activities (p=0.0002; r=0.5945), TBARS levels and ADA (p=0.0021; r=0.5172) and DPP-IV activities (p=0.0022; r=0.5010). CONCLUSIONS: Our findings showed that MetS might cause tissue distress that disturbed lymphocytic ADA, DPP-IV and AChE activities in response to inflammatory stimuli. These alterations evidence clinical abnormalities, since these enzymatic systems are able to regulate several aspects of adipose tissue function and inflammatory state of MetS and could be used successfully both for preventing and for halting the progression of MetS.

Urinary vanin-1 as a novel biomarker for early detection of drug-induced acute kidney injury.

Drug-induced nephrotoxicity is a serious problem in patients with hospital-acquired acute kidney injury (AKI). A new renal biomarker is needed because traditional markers are not sensitive for early detection of drug-induced AKI. In a recent study, we demonstrated that vanin-1 is a novel candidate biomarker of nephrotoxicant-induced kidney injury. The objective of the present study is to determine whether the increase in urinary vanin-1 is detected before the elevations of serum creatinine or urinary N-acetyl-ß-glucosaminidase (NAG), kidney injury molecule-1 (Kim-1), and neutrophil gelatinase-associated lipocalin (NGAL) in the two well established animal models of drug-induced AKI. After the administration of a higher dose of cisplatin (10 mg/kg, a single intraperitoneal dose) or gentamicin (120 mg/kg per day, once daily intraperitoneal dose for 9 days), urinary vanin-1 was detected earlier than the other biomarkers. In rats treated with a lower dose of cisplatin (5 mg/kg, a single intraperitoneal dose) or gentamicin (40 mg/kg per day, once daily intraperitoneal dose for 9 days), serum creatinine and urinary NAG were not changed throughout the study period, whereas urinary vanin-1, Kim-1, and NGAL were significantly increased. The renal vanin-1 protein levels were significantly decreased in rats treated with the higher dose of cisplatin on day 5 and gentamicin on day 9, and the immunofluorescence analyses confirmed that vanin-1 immunoreactivity in tubular cells was reduced with the time after the dose of cisplatin, indicating that urinary vanin-1 was leaked from tubular cells. These results suggest that, compared with urinary Kim-1 and NGAL, urinary vanin-1 is an earlier and equally sensitive biomarker for drug-induced AKI.

Molecular cloning and catalytic mechanism of a novel glycosphingolipid-degrading beta-N-acetylgalactosaminidase from Paenibacillus sp. TS12.

We report here the molecular cloning, characterization, and catalytic mechanism of a novel glycosphingolipid-degrading ß-N-acetylgalactosaminidase (ß-NGA) from Paenibacillus sp. TS12 (NgaP). Consisting of 1034 putative amino acid residues, NgaP shares no sequence similarity with known proteins. Recombinant NgaP, expressed in Escherichia coli, cleaved the nonreducing terminal ß-GalNAc residues of gangliotriaosylceramide and globotetraosylceramide. The enzyme hydrolyzed para-nitrophenyl-ß-N-acetylgalactosaminide ∼100 times faster than para-nitrophenyl-ß-N-acetylglucosaminide. GalNAc thiazoline, an analog of the oxazolinium intermediate and potent inhibitor for enzymes adopting substrate-assisted catalysis, competitively inhibited the enzyme. The K(i) of the enzyme for GalNAc thiazoline was 1.3 nM, whereas that for GlcNAc thiazoline was 46.8 µM. Comparison of the secondary structure with those of known enzymes exhibiting substrate-assisted catalysis and point mutation analysis indicated that NgaP adopts substrate-assisted catalysis in which Glu-608 and Asp-607 could function as a proton donor and a stabilizer of the 2-acetamide group of the ß-GalNAc at the active site, respectively. These results clearly indicate that NgaP is a ß-NGA showing substrate-assisted catalysis. This is the first report describing the molecular cloning of a ß-NGA adopting substrate-assisted catalysis.

Possible involvement of intracellular angiotensin II receptor in high-glucose-induced damage in renal proximal tubular cells.

BACKGROUND: Recent studies have identified high glucose as a potent stimulus for the intracellular synthesis of angiotensin II. However, the exact roles of angiotensin II and angiotensin II type 1 receptor blockers (ARB) in high-glucose-induced renal tubular function remain unclear. METHODS: N-Acetyl-beta-glucosaminidase (NAG), angiotensin II and 8-hydroxy-2'-deoxyguanosine (8-OHdG) concentrations in renal proximal tubular epithelial cells (RPTECs) with or without high glucose/ARB were determined using a modified commercial procedure. The changes of p22phox and cytoplasmic inhibitory kappa B (IkB) protein levels in RPTECs were measured using Western blotting. RESULTS: High-glucose treatment (4x10-2 mol/L) significantly increased NAG release, angiotensin II concentrations in cell lysates and 8-OHdG and p22phox protein levels compared with those in regular glucose medium (1.75x10(-2) mol/L). ARBs (candesartan, olmesartan or valsartan; 1x10(-9)-10(-7) mol/L) showed a significant reduction in high-glucose-induced NAG, 8-OHdG and p22phox protein levels in RPTECs. Significant decreases of cytoplasmic IkB protein levels were observed in the high-glucose-treated group in RPTECs. ARBs markedly reversed high-glucose-induced reduction of IkB protein levels in RPTECs. CONCLUSIONS: ARBs reduce high-glucose-induced oxidative stress in RPTECs possibly via blockade of intracellular as well as extracellular AT1 receptor signaling, which possibly protects renal tubular cell function during diabetic nephropathy.

Muropeptide rescue in Bacillus subtilis involves sequential hydrolysis by beta-N-acetylglucosaminidase and N-acetylmuramyl-L-alanine amidase.

We identified a pathway in Bacillus subtilis that is used for recovery of N-acetylglucosamine (GlcNAc)-N-acetylmuramic acid (MurNAc) peptides (muropeptides) derived from the peptidoglycan of the cell wall. This pathway is encoded by a cluster of six genes, the first three of which are orthologs of Escherichia coli genes involved in N-acetylmuramic acid dissimilation and encode a MurNAc-6-phosphate etherase (MurQ), a MurNAc-6-phosphate-specific transcriptional regulator (MurR), and a MurNAc-specific phosphotransferase system (MurP). Here we characterized two other genes of this cluster. The first gene was shown to encode a cell wall-associated beta-N-acetylglucosaminidase (NagZ, formerly YbbD) that cleaves the terminal nonreducing N-acetylglucosamine of muropeptides and also accepts chromogenic or fluorogenic beta-N-acetylglucosaminides. The second gene was shown to encode an amidase (AmiE, formerly YbbE) that hydrolyzes the N-acetylmuramyl-L-Ala bond of MurNAc peptides but not this bond of muropeptides. Hence, AmiE requires NagZ, and in conjunction these enzymes liberate MurNAc by sequential hydrolysis of muropeptides. NagZ expression was induced at late exponential phase, and it was 6-fold higher in stationary phase. NagZ is noncovalently associated with lysozyme-degradable particulate material and can be released from it with salt. A nagZ mutant accumulates muropeptides in the spent medium and displays a lytic phenotype in late stationary phase. The evidence for a muropeptide catabolic pathway presented here is the first evidence for cell wall recovery in a Gram-positive organism, and this pathway is distinct from the cell wall recycling pathway of E. coli and other Gram-negative bacteria.

Glycosidase determination in bovine oviducal fluid at the follicular and luteal phases of the oestrous cycle.

Gamete recognition and binding of spermatozoa to the oviduct are carbohydrate-mediated processes in which several glycosidases are thought to have a role, although this has not been demonstrated unequivocally. Oviducal fluid is the biological milieu in which fertilisation and early embryo development take place, but the enzyme composition of oviducal fluid is largely unknown. The aim of the present study was to determine glycosidase activity and protein content in bovine oviducal fluid (bOF) and the volume of fluid collected per oviduct. Oviducts obtained from a slaughterhouse were classified as either in the follicular or luteal phase on the basis of ovarian luteal morphology. Oviducal fluid was aspirated, centrifuged and the volume determined. Samples were then frozen until assay. Substrates conjugated to 4-methylumbelliferyl were used to screen for the activity of seven glycosidases at pH 7.2. The results indicate that bOF has alpha-l-fucosidase, beta-N-acetyl-glucosaminidase, beta-d-galactosidase, alpha-D-mannosidase and beta-N-acetyl-galactosaminidase activity during both phases of the cycle, with the specific activity of the latter two enzymes being higher during the follicular phase. There was no N-acetyl-neuraminidase or alpha-d-galactosidase activity detected in bOF at either phase of the oestrous cycle at pH 7.2, but activity for both glycosidases was detected at pH 4.4. There were no differences in protein concentration or the volume of bOF collected between the two phases of the cycle. These findings indicate that oviducal fluid exhibits glycosidase activity, with specific variations throughout the oestrous cycle, suggesting that these enzymes play a role in carbohydrate-mediated events.

Determination of glycosidase activity in porcine oviductal fluid at the different phases of the estrous cycle.

Sperm-oocyte binding and gamete-oviductal epithelium interactions are carbohydrate-mediated events occurring in the oviductal fluid (OF). Thus, knowledge about the activities of glycosidases (enzymes catalyzing hydrolytic cleavage of terminal sugar residues) in this milieu would help us understand the molecular mechanisms involved in these events. This work was carried out to investigate the glycosidase activity, protein content, and volume of OF collected from gilts and sows. Oviducts were classified into four phases of the estrous cycle (early follicular, late follicular, early luteal, and late luteal) based on the appearance of the ovaries. OF was aspirated, centrifuged, measured for volume, and frozen until assay. Substrates conjugated to 4-methylumbelliferyl were used to screen the activities of seven different glycosidases at physiological pH (7.2). alpha-L-Fucosidase and beta-N-acetyl-glucosaminidase activities increased at the late follicular phase to decrease after ovulation. beta-D-Galactosidase, alpha-D-mannosidase, and beta-N-acetyl-galactosaminidase showed higher activities at the early follicular phase, which decreased after ovulation. N-Acetyl-neuraminidase and alpha-D-galactosidase did not show activity at any phase of estrous cycle neither in sows nor in gilts at pH 7.2, although it did at acidic pH (4.4) in the follicular and luteal phase samples. Total protein also changed during the cycle showing the maximum secretion at the late follicular phase (2118.6+/-200.7 microg/oviduct). The highest volumes of OF were collected from the oviducts at the late follicular phase (50.7+/-1.3 microl/oviduct). These results indicate that OF from sows and gilts shows glycosidase activity varying throughout the estrous cycle suggesting a role of these enzymes in carbohydrate-mediated events.

TMG-chitotriomycin, an enzyme inhibitor specific for insect and fungal beta-N-acetylglucosaminidases, produced by actinomycete Streptomyces anulatus NBRC 13369.

A novel beta-N-acetylglucosaminidase (GlcNAcase) inhibitor named TMG-chitotriomycin (1) was isolated from the culture filtrate of Streptomyces anulatus NBRC13369. The strain produced 1 only when colloidal chitin was used as the sole carbon source in the production medium. The structure of 1 was determined by spectral and constitutive sugar analyses of the corresponding alditol derivatives to be an equilibrated mixture of alpha-d-N,N,N-triMeGlcNH2-(1,4)-beta-d-GlcNAc-(1,4)-beta-d-GlcNAc-(1,4)-d-GlcNAc and its C-2 epimer of the reducing end residue. TMG-chitotriomycin (1) showed potent and selective inhibition of insect and fungal GlcNAcases with no inhibition of mammalian and plant GlcNAcases. In contrast, the known GlcNAcase inhibitor nagstatin potently inhibited all GlcNAcases. It should be emphasized that synthesized d-N,N,N-triMeGlcNH2, which is the component sugar of 1, showed no inhibition of the insect Spodoptera litura GlcNAcase. These results suggest that the (GlcNAc)3 unit positioned at the reducing end of 1 is essential for its enzyme inhibitory activity. The unique inhibitory spectrum of 1 will be useful to study chitinolytic systems and to develop selective fungicides or pesticides.

A 1-acetamido derivative of 6-epi-valienamine: an inhibitor of a diverse group of beta-N-acetylglucosaminidases.

The synthesis of an analogue of 6-epi-valienamine bearing an acetamido group and its characterisation as an inhibitor of beta-N-acetylglucosaminidases are described. The compound is a good inhibitor of both human O-GlcNAcase and human beta-hexosaminidase, as well as two bacterial beta-N-acetylglucosaminidases. A 3-D structure of the complex of Bacteroides thetaiotaomicron BtGH84 with the inhibitor shows the unsaturated ring is surprisingly distorted away from its favoured solution phase conformation and reveals potential for improved inhibitor potency.

Prevalence of chronic kidney disease in a middle and old-aged population of Beijing.

BACKGROUND: Chronic kidney disease (CKD) was epidemic worldwide. The prevalence of CKD indicators, including proteinuria, hematuria/uninfectious leukocyturia and reduced GFR, was investigated in the middle and old-aged population of Beijing Shijingshan district. METHODS: Subjects of 2310 aged > or =40 y were enrolled. Their health conditions were taken by questionnaires and physical check-ups. Spot urine albumin to creatinine ratio, spot urine dipstick and microscopy for urine red cell and leukocyte, and serum creatinine was determined. Using simplified Modification of Diet in Renal Disease Study equation estimated GFR assessed renal function. The associations between age, gender, diabetes mellitus, and hypertension, and indicators of kidney damage were examined. RESULTS: Through the questionnaires, the history of diabetes mellitus, hypertension and CKD were found in 28%, 47.1% and 3.6% of subjects, respectively. Albuminuria was detected in 8.4% of subjects, hematuria and uninfectious leukocyturia in 0.7%, and reduced GFR in 4.9%. Approximately 12.9% had at least 1 indicator of CKD. The known rate of CKD in the studied population was 7.1%. Age, diabetes mellitus, hyper fasting blood glucose and hypertension were independently associated with albuminuria; age, gender, hyper uric acid and albuminuria with reduced GFR. When proteinuria and reduced GFR were determined using spot urine dipstick protein > or =25 mg/dl and serum creatinine > or =133 micromol/l, the prevalence of proteinuria and reduced GFR were 4.7% and 0.8%, respectively. CONCLUSION: The prevalence of CKD is common in middle and old-aged population of Beijing, especially in the elderly, but the known rate was relatively low. These findings highlight the clinical and public health importance of CKD.