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Articles by H Yu
Total Records ( 11 ) for H Yu
  C. G Sharoff , T. A Hagobian , S. K Malin , S. R Chipkin , H Yu , M. F Hirshman , L. J Goodyear and B. Braun
 

Results from the Diabetes Prevention Program highlight the effectiveness of metformin or regular physical activity in the prevention of type 2 diabetes. Independently, metformin and exercise increase insulin sensitivity, but they have not been studied in combination. To assess the combined effects, insulin-resistant subjects (n = 9) matched for weight, body fat, and aerobic fitness were studied before any treatment (B), after 2–3 wk of 2,000 mg/day metformin (MET), and after metformin plus 40 min of exercise at 65% Vo2peak (MET + Ex). A second group (n = 7) was studied at baseline and after an identical bout of exercise with no metformin (Ex). Biopsies of the vastus lateralis were taken at B, after MET, immediately after MET + Ex (group 1), or immediately after Ex (group 2). Insulin sensitivity was assessed 4 h postexercise with a euglycemic hyperinsulinemic (40 mU·m2·min–1) clamp enriched with [6,6-2H]glucose. Insulin sensitivity was 54% higher after Ex (P < 0.01), but there was no change with Met + Ex. Skeletal muscle AMPK2 activity was elevated threefold (P < 0.01) after Ex, but there was no increase with MET + Ex. These findings suggest that the combination of short-term metformin treatment and an acute bout of exercise does not enhance insulin sensitivity, and the addition of metformin may attenuate the well-documented effects of exercise alone.

  Y Tan , Y Li , J Xiao , H Shao , C Ding , G. E Arteel , K. A Webster , J Yan , H Yu , L Cai and X. Li
  Aims

The effects on angiogenesis of a novel CXC chemokine receptor 4 (CXCR4) antagonist, SDF-1βP2G, derived from human stromal cell-derived factor-1β (SDF-1β), were examined in a model of hind limb ischaemia in mice.

Methods and results

The antagonistic activities of SDF-1βP2G against CXCR4 were evaluated in vitro and in vivo and compared with phosphate-buffered saline and AMD3100 (a small bicyclam antagonist of SDF-1). Angiogenesis, muscle regeneration and the expression of pro-angiogenic factors were evaluated in ischaemic gastrocnemius muscles. Distant toxic effects of SDF-1βP2G were evaluated by inflammatory and apoptotic markers. SDF-1βP2G induced CXCR4 internalization and competitively inhibited the chemotaxis of SDF-1β but did not mediate migration, calcium influx, or the phosphorylation of Akt and extracellular signal-regulated kinase in cultured T-lymphoblastic leukaemia cells or H9C2 cells. SDF-1βP2G enhanced blood flow, angiogenesis, and muscle regeneration in ischaemic hind limbs, and the enhancement was significantly better than that of AMD3100. Markers of angiogenesis and progenitor cell migration, including phosphorylated Akt, vascular endothelial growth factor (VEGF), SDF-1 and CXCR4, were up-regulated by SDF-1βP2G and co-localized with CD31-positive cells. Neutralization of VEGF with its specific antibody abolished SDF-1βP2G-induced blood reperfusion and angiogenesis. No apparent inflammatory and apoptotic effects were found in heart, liver, kidneys, and testes after SDF-1βP2G administration.

Conclusion

Our findings indicate that the novel CXCR4 antagonist, SDF-1βP2G, can efficiently enhance ischaemic angiogenesis, blood flow restoration, and muscle regeneration without apparent adverse effects, most likely through a VEGF-dependent pathway.

  M Zheng , W Liang , H Yu and Y. Xiao
 

In the following paper, we study the tradeoff between network utility and network lifetime for energy-constrained wireless sensor networks (WSNs). By introducing a weighted factor, we combine these two objectives into a single weighted objective, and we consider rate control and routing in this tradeoff framework simultaneously. First, by using a dual decomposition method, we decompose the tradeoff model into two subproblems: the congestion control/routing problem and the network lifetime problem, both of which interact through the dual variables for energy dissipation constraints. Based on the decomposition results, we propose a fully distributed algorithm to solve these two sub-problems and the dual problem by using gradient and sub-gradient projection methods. Second, we propose a fully distributed algorithm by approximating the network lifetime maximization problem by using the network utility maximization (NUM) framework. Third, we extend our distributed algorithm to deal with reliable communication and the real-time requirement. Rigorous analysis and simulations are presented to validate our algorithms.

  Y He , Y Li , Z Peng , H Yu , X Zhang , L Chen , Q Ji , W Chen and R. Wang
 

A prominent feature of the rodent Muc3 SEA module is the precursor cleavage event that segregates the O-glycosylated N-terminal fragment and transmembrane domain into the noncovalently attached heterodimer. There are seven potential N-glycosylation sites that occur in a cluster in the SEA module of Muc3. However, it is unknown if these sites are modified or what the function of these N-glycans may be in the SEA module. Our data show that the proteolytic cleavage of the rodent Muc3 SEA module was partially prevented by treatment with tunicamycin, an inhibitor of N-glycosylation. Each single mutant of the seven N-glycosylation sites (N1A, N2A, N3A, N4A, N5A, N6A, and N7A) and multiple mutants, including double (N34A) and triple (N345A) mutants, and mutants with four (N3457A), five (N34567A), six (N134567A and N234567A), seven (N1234567A) mutations, confirmed that all seven of these potential sites are N-glycosylated simultaneously. The proteolytic cleavage of the SEA module was not affected when it lacked only one, two, or three N-glycans, but was partially inhibited when lacking four, five, and six N-glycans. In all, 2%, 48%, 85%, and 73% of the products from N3457A, N34567A, N134567A, and N234567A transfectants, respectively, remained uncleaved. The proteolytic cleavage was completely prevented in the N1234567A transfectant, which eliminated all seven N-glycans in the SEA module. The interaction of the heterodimer was independent of the N-glycans within the rodent Muc3 SEA module. Thus, the N-glycosylation pattern constituted a control point for the modulation of the proteolytic cleavage of the SEA module.

  J Cheng , S Huang , H Yu , Y Li , K Lau and X. Chen
 

Trans-sialidases catalyze the transfer of a sialic acid from one sialoside to an acceptor to form a new sialoside. 2,3-Trans-sialidase activity was initially discovered in the parasitic protozoan Trypanosoma cruzi, and more recently was found in a multifunctional Pasteurella multocida sialyltransferase PmST1. 2,8-Trans-sialidase activity was also described for a multifunctional Campylobacter jejuni sialyltransferase CstII. We report here the discovery of the 2,6-trans-sialidase activity of a previously reported recombinant truncated bacterial 2,6-sialyltransferase from Photobacterium damsela (15Pd2,6ST). This is the first time that the 2,6-trans-sialidase activity has ever been identified. Kinetic studies indicate that 15Pd2,6ST-catalyzed trans-sialidase reaction follows a ping-pong bi-bi reaction mechanism. Cytidine 5'-monophosphate, the product of sialyltransferase reactions, is not required by the trans-sialidase activity of the enzyme but enhances the trans-sialidase activity modestly as a non-essential activator. Using chemically synthesized Neu5AcpNP and LacβMU, 2,6-linked sialoside Neu5Ac2,6LacβMU has been obtained in one-step in high yield using the trans-sialidase activity of 15Pd2,6ST. In addition to the 2,6-trans-sialidase activity, 15Pd2,6ST also has 2,6-sialidase activity. The multifunctionality is thus a common feature of many bacterial sialyltransferases.

  L Zhang , K Lau , J Cheng , H Yu , Y Li , G Sugiarto , S Huang , L Ding , V Thon , P. G Wang and X. Chen
 

Lewis x (Lex) and sialyl Lewis x (SLex)-containing glycans play important roles in numerous physiological and pathological processes. The key enzyme for the final step formation of these Lewis antigens is 1-3-fucosyltransferase. Here we report molecular cloning and functional expression of a novel Helicobacter hepaticus 1-3-fucosyltransferase (HhFT1) which shows activity towards both non-sialylated and sialylated Type II oligosaccharide acceptor substrates. It is a promising catalyst for enzymatic and chemoenzymatic synthesis of Lex, sialyl Lex and their derivatives. Unlike all other 1-3/4-fucosyltransferases characterized so far which belong to Carbohydrate Active Enzyme (CAZy, http://www.cazy.org/) glycosyltransferase family GT10, the HhFT1 shares protein sequence homology with 1-2-fucosyltransferases and belongs to CAZy glycosyltransferase family GT11. The HhFT1 is thus the first 1-3-fucosyltransferase identified in the GT11 family.

  H. A Risch , H Yu , L Lu and M. S. Kidd
 

Carriage of a non–O ABO blood group and colonization by Helicobacter pylori are thought to be risk factors for pancreatic cancer. We examined these associations in a population-based case–control study of 373 case patients and 690 control subjects frequency matched on sex and age. Control subjects were selected by random-digit dialing. Seropositivity for H pylori and its virulence protein CagA was determined by enzyme-linked immunosorbent assay (ELISA). Increased risk of pancreatic cancer was associated with non–O blood group (adjusted odds ratio [OR] = 1.37, 95% confidence interval [CI] = 1.02 to 1.83, P = .034) and CagA-negative H pylori seropositivity (OR = 1.68, 95% CI = 1.07 to 2.66, P = .025), but no association was observed for CagA seropositivity (OR = 0.77, 95% CI = 0.52 to 1.16). An association between pancreatic cancer risk and CagA-negative H pylori seropositivity was found among individuals with non–O blood type but not among those with O blood type (OR = 2.78, 95% CI = 1.49 to 5.20, P = .0014; OR = 1.28, 95% CI = 0.62 to 2.64, P = .51, respectively). This study demonstrates an association between pancreatic cancer and H pylori colonization, particularly for individuals with non–O blood types.

  K Wang , D Tang , M Wang , J Lu , H Yu , J Liu , B Qian , Z Gong , X Wang , J Chen , M Gu and Z. Cheng
  Kejian Wang, Ding Tang, Mo Wang, Jufei Lu, Hengxiu Yu, Jiafan Liu, Baoxiang Qian, Zhiyun Gong, Xin Wang, Jianmin Chen, Minghong Gu, and Zhukuan Cheng

MER3, a ZMM protein, is required for the formation of crossovers in Saccharomyces cerevisiae and Arabidopsis. Here, MER3, the first identified ZMM gene in a monocot, is characterized by map-based cloning in rice (Oryza sativa). The null mutation of MER3 results in complete sterility without any vegetative defects. Cytological analyses show that chiasma frequency is reduced dramatically in mer3 mutants and the remaining chiasmata distribute randomly among different pollen mother cells, implying possible coexistence of two kinds of crossover in rice. Immunocytological analyses reveal that MER3 only exists as foci in prophase I meiocytes. In addition, MER3 does not colocalize with PAIR2 at the beginning of prophase I, but locates on one end of PAIR2 fragments at later stages, whereas MER3 foci merely locate on one end of REC8 fragments when signals start to be seen in early prophase I. The normal loading of PAIR2 and REC8 in mer3...

  A. L Bi , Y Wang , B. Q Li , Q. Q Wang , L Ma , H Yu , L Zhao and Z. Y. Chen
 

Actin rearrangement plays an essential role in learning and memory; however, the spatial and temporal regulation of actin dynamics in different phases of associative memory has not been fully understood. Here, using the conditioned taste aversion (CTA) paradigm, we investigated the region-specific involvement of actin rearrangement-related synaptic structure alterations in different memory processes. We found that CTA training could induce increased postsynaptic density (PSD) length in insular cortex (IC), but not in basolateral amygdala (BLA) and prelimbic cortex (PrL) during short-term memory (STM) formation, whereas it led to increased PSD length and synapse density in both IC and PrL during long-term memory (LTM) formation. Inhibition of actin rearrangement in the IC, but not in the BLA and PrL, impaired memory acquisition. Furthermore, actin dynamics in the IC or PrL is necessary for memory consolidation. On the contrary, inhibition of actin dynamics in the IC, BLA, or PrL had no effect on CTA memory retrieval. Our results suggest temporal and regional-specific regulation of actin rearrangement-related synaptic structure in different phases of CTA memory.

  N Chen , W Wang , Y Huang , P Shen , D Pei , H Yu , H Shi , Q Zhang , J Xu , Y Lv and Q. Fan
 

Background. The study was performed to investigate the prevalence, awareness and the risk factors of chronic kidney disease (CKD) in the community population in Shanghai, China.

Methods. A total of 2596 residents were randomly recruited from the community population in Shanghai, China. All were screened for albuminuria, haematuria, morning spot urine albumin-to-creatinine ratio and renal function. Serum creatinine, uric acid, cholesterol, triglyceride and haemoglobin were assessed. A simplified MDRD equation was used to estimate the glomerular filtration rate (eGFR). All studied subjects were screened by kidney ultrasound. Haematuria, if present in the morning spot urine dipstick test, was confirmed by microscopy. The associations among the demographic characteristics, health characteristics and indicators of kidney damage were examined.

Results. Two thousand five hundred and fifty-four residents (n = 2554), after giving informed consent and with complete data, were entered into this study. Albuminuria and haematuria were detected in 6.3% and 1.2% of all the studied subjects, respectively, whereas decreased kidney function was found in 5.8% of all studied subjects. Approximately 11.8% of subjects had at least one indicator of kidney damage. The rate of awareness of CKD was 8.2%. The logistic regression model showed that age, central obesity, hypertension, diabetes, anaemia, hyperuricaemia and nephrolithiasis each contributed to the development of CKD.

Conclusion. This is the first Shanghai community-based epidemiological study data on Chinese CKD patients. The prevalence of CKD in the community population in Shanghai is 11.8%, and the rate of awareness of CKD is 8.2%. All the factors including age, central obesity, hypertension, diabetes, anaemia, hyperuricaemia and nephrolithiasis are positively correlated with the development of CKD in our studied subjects.

  R. E Taylor , C. J Gregg , V Padler Karavani , D Ghaderi , H Yu , S Huang , R. U Sorensen , X Chen , J Inostroza , V Nizet and A. Varki
 

The nonhuman sialic acid N-glycolylneuraminic acid (Neu5Gc) is metabolically incorporated into human tissues from certain mammalian-derived foods, and this occurs in the face of an anti-Neu5Gc "xeno-autoantibody" response. Given evidence that this process contributes to chronic inflammation in some diseases, it is important to understand when and how these antibodies are generated in humans. We show here that human anti-Neu5Gc antibodies appear during infancy and correlate with weaning and exposure to dietary Neu5Gc. However, dietary Neu5Gc alone cannot elicit anti-Neu5Gc antibodies in mice with a humanlike Neu5Gc deficiency. Other postnatally appearing anti-carbohydrate antibodies are likely induced by bacteria expressing these epitopes; however, no microbe is known to synthesize Neu5Gc. Here, we show that trace exogenous Neu5Gc can be incorporated into cell surface lipooligosaccharides (LOS) of nontypeable Haemophilus influenzae (NTHi), a human-specific commensal/pathogen. Indeed, infant anti-Neu5Gc antibodies appear coincident with antibodies against NTHi. Furthermore, NTHi that express Neu5Gc-containing LOS induce anti-Neu5Gc antibodies in Neu5Gc-deficient mice, without added adjuvant. Finally, Neu5Gc from baby food is taken up and expressed by NTHi. As the flora residing in the nasopharynx of infants can be in contact with ingested food, we propose a novel model for how NTHi and dietary Neu5Gc cooperate to generate anti-Neu5Gc antibodies in humans.

 
 
 
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