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Biomedical subjects

Y M Li

Publications and source records attributed to Y M Li.

At least 19 recordsLinked to original sources
PubMed2006

High prevalence of albuminuria in population-based patients diagnosed with type 2 diabetes in the Shanghai downtown.

OBJECTIVE: The prevalence of albuminuria and the risk factors associated with albuminuria were evaluated among the Chinese patients diagnosed with type 2 diabetes aged over 30 in the Shanghai downtown. We also evaluated the variability of urinary albumin-to-creatinine ratio (ACR) among the three measurements and the relationship between diabetic retinopathy (DR) and albuminuria. METHODS: The 1039 Chinese patients diagnosed with type 2 diabetes aged over 30 were investigated by randomized cluster sampling in the Shanghai downtown and 1018 patients were analyzed in this study. Body mass measurements including height, weight, waist circumference and hip circumference, resting blood pressure, fasting blood measures, urinary ACR and the digitally stored fundus images were investigated. The prevalence of albuminuria was calculated and the risk factors associated with albuminuria were evaluated by stepwise logistic regression. The concordance of urinary ACR was evaluated by observed agreement. The relationship between albuminuria and DR was also evaluated. RESULTS: (1) The mean age of all patients was 66.10+/-11.54 years and the duration of diabetes was 7.89+/-7.16 years. (2) The prevalence of albuminuria was 49.6% among the Chinese patients diagnosed with type 2 diabetes aged over 30 in the Shanghai downtown, 41.4% with microalbuminuria and 8.2% with macroalbuminuria. (3) Microalbuminuria was significantly associated with systolic blood pressure, gender and waist circumference. Macroalbuminuria was significantly associated with systolic blood pressure and duration of diabetes. (4) Observed agreement among the three urinary ACR measurement for albuminuria staging was 73.3% (first versus second), 64.5% (first versus third) and 77.5% (second versus third). Observed agreement in the albuminuria staging between the single urinary ACR measurement and all three urinary ACR measurements was 85.8% (first versus all three), 87.6% (second versus all three) and 81.9% (third versus all three). (5) The percentage of DR in the macroalbuminuric group (59.2%) was significantly higher than that in the normalbuminuria group (16.1%) and microalbuminuria group (24.6%). (6) The macroalbuminuric patients with DR had significantly increased fasting blood glucose and HbA1c compared with the macroalbuminuric patients without DR. CONCLUSION: The prevalence of microalbuminuria observed in the Chinese patients diagnosed with type 2 diabetes aged over 30 in the Shanghai downtown reached up to 41.4% though the observations in our study might be representative of the diabetic patients of the Shanghai downtown. We agreed that at least two of the three urinary collections were done in a 3- to 6-month period because of the day-to-day variability in albumin excretion. The percentage of DR among the patients with macroalbuminuria was 59.2%, and the macroalbuminuric patients with the significantly high plasma glucose and DR were prone to diagnose DN.

Adult↗
PubMed2006

Effects of phenylephrine on transplanted submandibular gland.

Autotransplantation of the submandibular gland is a potential treatment for severe kerato-conjunctivitis sicca. However, one of the major barriers to this procedure is that secretions from the transplanted gland decrease shortly after the operation, which may lead to obstruction of Wharton's duct, or even to transplantation failure. Using a rabbit model, we investigated whether phenylephrine could improve the secretion from the transplanted gland. We found that phenylephrine treatment significantly reversed the decrease in salivary secretion after transplantation, enhanced the expressions of alpha1A-, alpha1B-, and alpha1D-adrenoceptor mRNA, and ameliorated atrophy of acinar cells. Furthermore, phenylephrine also induced translocation of aquaporin-5 from the cytoplasm to the apical membrane, and increased the levels of phospho-ERK1/2, ERK1/2, phospho-PKCzeta, and PKCzeta in the transplanted gland. These results indicate that phenylephrine treatment moderates structural injury and improves secretory function in the transplanted submandibular gland through promoting alpha1-adrenoceptor expression and post-receptor signal transduction.

Adrenergic alpha-Agonists↗
PubMed2005

The SARS outbreak in a general hospital in Tianjin, China -- the case of super-spreader.

Severe acute respiratory syndrome (SARS) is a newly emerged infectious disease with a high case-fatality rate and devastating socio-economic impact. In this report we summarized the results from an epidemiological investigation of a SARS outbreak in a hospital in Tianjin, between April and May 2003. We collected epidemiological and clinical data on 111 suspect and probable cases of SARS associated with the outbreak. Transmission chain and outbreak clusters were investigated. The outbreak was single sourced and had eight clusters. All SARS cases in the hospital were traced to a single patient who directly infected 33 people. The patients ranged from 16 to 82 years of age (mean age 38.5 years); 38.7% were men. The overall case fatality in the SARS outbreak was 11.7% (13/111). The outbreak lasted around 4 weeks after the index case was identified. SARS is a highly contagious condition associated with substantial case fatality; an outbreak can result from one patient in a relatively short period. However, stringent public health measures seemed to be effective in breaking the disease transmission chain.

Adolescent↗
PubMed2005

Aggregation between xanthan and nonyphenyloxypropyl beta-hydroxyltrimethylammonium bromide in aqueous solution: MesoDyn simulation and binding isotherm measurement.

The aggregation behavior of nonyphenyloxypropyl beta-hydroxyltrimethylammonium bromide (C9phNBr) and xanthan (XC) in aqueous solution was investigated by MesoDyn density functional simulation and binding isotherm measurement. The process of aggregate formation and the aggregate morphology are reported. The formation of aggregates includes three stages and the morphology of XC-C9phNBr aggregates is rodlike or ellipsoidal. The effects of temperature and XC concentration on the aggregation are analyzed. Results indicate that the formation of aggregates is an exothermic process, and their formation becomes more difficult and the formation rate decreases with increasing temperature. The formation of aggregates is also related to XC concentration, and it becomes much more difficult when the concentration of XC is higher than 20 vol %. The simulation results agree with binding isotherms of C9phNBr to XC obtained via the potentiometric titration method, which shows a typical cooperative binding between C9phNBr and XC.

Journal Article↗
PubMed2004

Characterization and demulsification of poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) copolymers.

Four poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) copolymers with different molecular weights and PPO/PEO composition ratios were synthesized. The characterization of the PEO-PPO-PEO triblock copolymers was studied by surface tension measurement, UV-vis spectra, and surface pressure method. These results clearly showed that the CMC of PEO-PPO-PEO was not a certain value but a concentration range, in contrast to classical surfactant, and two breaks around CMC were reflected in both surface tension isotherm curves and UV-vis absorption spectra. The range of CMC became wider with increasing PPO/PEO composition ratio. Surface pressure Pi-A curves revealed that the amphiphilic triblock copolymer PEO-PPO-PEO molecule was flexible at the air/water interface. We found that the minimum area per molecule at the air/water interface increased with the proportion of PEO chains. The copolymers with the same mass fractions of PEO had similar slopes in the isotherm of the Pi-A curve. From the demulsification experiments a conclusion had been drawn that the dehydration speed increased with decreased content of PEO, but the final dehydration rate of four demulsifiers was approximate. We determined that the coalescence of water drops resulted in the breaking of crude oil emulsions from the micrograph.

Emulsions↗
PubMed2004

N-phosphoryl amino acids and biomolecular origins.

The possible role of phosphoryl amino acids for biomolecular origins is briefly reviewed. Peptide formation, ester formation, ester exchange on phosphorus and N to O migration occurred when the N-phosphoryl amino acid was incubated at room temperature. Short nucleotides and peptides were formed when nucleoside was reacted with N-phosphoryl amino acid at room temperature. Serine and threonine residues in their conjugate with different nucleosides (mediated with phosphorus) showed different self-cleavage activities. N-phosphoryl Histine and Ser-His dipeptide could cleave nucleic acids, proteins and esters in neutral medium. Based on a simple model, a pathway of 'co-evolution of protein and nucleic acid' was proposed.

Amino Acids↗
PubMed2003

Epidemiology and cause of severe acute respiratory syndrome (SARS) in Guangdong, People's Republic of China, in February, 2003.

BACKGROUND: An epidemic of severe acute respiratory syndrome (SARS) has been associated with an outbreak of atypical pneumonia originating in Guangdong Province, People's Republic of China. We aimed to identify the causative agent in the Guangdong outbreak and describe the emergence and spread of the disease within the province. METHODS: We analysed epidemiological information and collected serum and nasopharyngeal aspirates from patients with SARS in Guangdong in mid-February, 2003. We did virus isolation, serological tests, and molecular assays to identify the causative agent. FINDINGS: SARS had been circulating in other cities of Guangdong Province for about 2 months before causing a major outbreak in Guangzhou, the province's capital. A novel coronavirus, SARS coronavirus (CoV), was isolated from specimens from three patients with SARS. Viral antigens were also directly detected in nasopharyngeal aspirates from these patients. 48 of 55 (87%) patients had antibodies to SARS CoV in their convalescent sera. Genetic analysis showed that the SARS CoV isolates from Guangzhou shared the same origin with those in other countries, and had a phylogenetic pathway that matched the spread of SARS to the other parts of the world. INTERPRETATION: SARS CoV is the infectious agent responsible for the epidemic outbreak of SARS in Guangdong. The virus isolated from patients in Guangdong is the prototype of the SARS CoV in other regions and countries.

China↗
PubMed2003

Effect of different sample pretreatment methods on the concentrations of excitatory amino acids in cerebrospinal fluid determined by high-performance liquid chromatography.

Using high-performance liquid chromatography (HPLC), the effect of different sample pretreatment methods on the concentrations of excitatory amino acids (EAAs, glutamate and aspartate) measured in cerebrospinal fluid (CSF) was investigated. The results showed that the measured values of glutamate and aspartate were constant when the samples were stored at -80 degrees C and then methanol was used for CSF deproteinization before assay; the values of glutamate (Glu) increased when 0.3 M perchloric acid was used for CSF deproteinization with the CSF subsequently being stored at -20 degrees C; the values of Glu changed when the samples were stored at -20 degrees C over 8 weeks with methanol subsequently being used for CSF deproteinization before assay. This reference data suggested that the CSF sample would be better stored at -80 degrees C. If the sample is stored at -20 degrees C over 8 weeks, the Glu values change with the storage time. If strong acidic reagents are used for precipitation of protein in the CSF sample and then stored at -20 degrees C, Glu values are abnormally increased. From this study, an accurate and sensitive reversed-phase high-performance liquid chromatographic method has been developed for anti-excitotoxicity therapy and thorough study of EAAs in a clinical setting.

Aspartic Acid↗
PubMed2003

No evidence for linkage and/or association of human alpha2-HS glycoprotein gene with bone mineral density variation in Chinese nuclear families.

Osteoporosis is an important health problem in the world. Alpha2-HS glycoprotein (AHSG) is involved in bone formation and metabolism and has been considered as an important candidate gene for osteoporosis. In this study, we simultaneously tested linkage and/or association of the AHSG gene with the variation of bone mineral density (BMD), an important risk factor for osteoporosis. A sample of 1,260 subjects from 401 Chinese nuclear families (including both parents and their daughters) were studied. The daughters' ages ranged from 20 to 45 years. All the subjects were genotyped by PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism) at polymorphic Sac I site inside the exon 7 of the AHSG gene. This polymorphism involves a nucleotide substitution of C to G at the middle nucleotide of the codon at amino acid position 238, resulting in the replacement of threonine (ACC) with serine (AGC). BMD was measured at the lumbar spine and hip region by dual-energy X-ray absorptiometry (DXA). Using the QTDT (quantitative trait transmission disequilibrium test), we found no significant results for association or linkage between the AHSG gene and BMD variation at the spine or hip. Our data provided no evidence to support the AHSG gene as a quantitative trait locus (QTL) for the BMD variation in a Chinese population.

Absorptiometry, Photon↗
PubMed2003

Treatment of coke-plant wastewater by biofilm systems for removal of organic compounds and nitrogen.

Coke-plant wastewater was treated by an anaerobic-anoxic-aerobic (A(1)-A(2)-O) biofilm system and an anoxic-aerobic (A/O) biofilm system, respectively. At same or similar levels of hydraulic retention time (HRT), the two systems had almost identical chemical oxygen demand (COD) and NH(3) removals, but a different organic-N removal. Set-up of an acidogenic stage benefited for the removal of organic-N and the A(1)-A(2)-O system was more useful for total nitrogen removal than the A-O system. HRT did not have a substantial effect on the COD and NH(3)-N removal efficiencies, but considerably influenced the organic-N removal and distribution of oxidized nitrogen in the final effluent. The GC/MS analysis demonstrated that some refractory compounds were decomposed at the acidogenic stage and resulted in the production of some intermediates, which were more readily degraded in the subsequent aerobic stage. Hence, the A(1)-A(2)-O system had better effluent quality than the A-O system in terms of effluent composition.

Bacteria, Aerobic↗
PubMed2003

SARS: prognosis, outcome and sequelae.

Severe acute respiratory syndrome (SARS) is associated with considerable morbidity and mortality in the acute phase. Worldwide case fatality rate is 11% (range 7 to 27%) for the most severely affected regions. Several adverse prognostic factors have been identified, including advanced age, presence of comorbidity, higher lactose dehydrogenase levels and initial neutrophil count, but the impact of viral and other host factors on outcome is unknown. Published data on sequelae of SARS are limited. Clinical follow-up of patients who recovered from SARS has demonstrated radiological, functional and psychological abnormalities of varying degrees. In the early rehabilitation phase, many complained of limitations in physical function from general weakness and/or shortness of breath. In a small series of subjects who underwent CT scan of the chest, over half showed some patchy changes consistent with pulmonary fibrosis. Lung function testing at 6-8 weeks after hospital discharge showed mild or moderate restrictive pattern consistent with muscle weakness in 6-20% of subjects. Mild decrease in carbon monoxide diffusing capacity was detected in a minority of subjects. Preliminary evidence suggests that these lung function abnormalities will improve over time. Psychobehavioural problems of anxiety and/or depression were not uncommon in the early recovery phase, and improved over time in the majority of patients. Avascular necrosis of the hip has been reported as another complication. The long-term sequelae of SARS are still largely unknown. It is important to follow up these patients to detect and appropriately manage any persistent or emerging long-term sequelae in the physical, psychological and social domains.

Humans↗
PubMed2002

Free emboli formation in the wake of bi-leaflet mechanical heart valves and the effects of implantation techniques.

The high incidence of thromboembolic complications of mechanical heart valves (MHV), primarily due to platelet activation by contact with foreign surfaces and by non-physiological flow patterns past the valve, still limits their success as permanent implants. The latter include elevated shear and turbulent stresses and shed vortices formed in the wake of the valve's leaflets during the deceleration phase, potentially entrapping activated and aggregated platelets. It is hypothesized that these flow patterns induce the formation of free emboli which are the source of cerebrovascular microemboli associated with MHV. Implicit to this hypothesis is that free emboli formation will be affected by the implantation technique employed and the valve orientation, as those will alter the flow characteristics past the valve and the interaction of the platelets with the flow. In this study, numerical simulations of turbulent pulsatile flow past a St. Jude Medical bi-leaflet MHV were conducted. Platelet shear histories were calculated along pertinent turbulent platelet trajectories, and the effect of a misaligned valve on platelet activation was quantified and compared to that of an aligned valve. It demonstrated that the combination of a tilted valve and subannularly sutured pledgets had an explicit detrimental effect on platelet activation, with the following entrapment of the platelets within the shed vortices of the wake leading to a significant increase of the thromboembolic potential of the valve. This numerical model depicted a viable course for free emboli formation, and indicated how the implantation technique may enhance the risk of cardioembolism.

Aortic Valve↗
PubMed2001

The pro domain of beta-secretase does not confer strict zymogen-like properties but does assist proper folding of the protease domain.

beta-Secretase (BACE) is a membrane-bound aspartyl protease that cleaves the amyloid precursor protein to generate the N terminus of the amyloid beta peptide. BACE is expressed as a precursor protein containing Pre, Pro, protease, transmembrane, and cytosolic domains. A soluble BACE derivative (PreProBACE460) that is truncated between the protease and transmembrane domains was produced by baculovirus-mediated expression. ProBACE460 was purified from conditioned media of infected insect cells using immobilized concanavalin A and immobilized BACE inhibitor, P10-P4' Stat(Val). Furin cleaves ProBACE460 between the Pro and protease regions to generate mature BACE460. The k(cat)/K(m) of ProBACE460 when assayed with a polypeptide substrate is only 2.3-fold less than that of BACE460. This finding and the similar inhibitory potency of P10-P4' Stat(Val) for ProBACE460 and BACE460 suggest that the Pro domain has little effect on the BACE active site. Exposure of ProBACE460 to guanidine denaturation/renaturation results in a 7-fold higher recovery of BACE activity than when BACE460 is similarly treated. The presence of free BACE Pro peptide during renaturation of BACE460 but not ProBACE460 increases recovery of activity. These findings show that the Pro domain in ProBACE460 does not suppress activity as in a strict zymogen but does appear to facilitate proper folding of an active protease domain.

Amino Acid Sequence↗
PubMed2001

Analysis of extracellular gamma-aminobutyric acid, glutamate and aspartate in cat visual cortex by in vivo microdialysis and capillary electrophoresis-laser induced fluorescence detection.

To investigate the influence of a partial sensory deprivation on the extracellular concentration of amino acid neurotransmitters in cat visual cortex, a capillary electrophoresis method was developed for the quantification of gamma-aminobutyric acid (GABA), glutamate (Glu) and aspartate (Asp) in in vivo microdialysis samples of cat brain. Microdialysis samples from different regions of area 17 were obtained every 15-min using CMA 12 2-mm probes perfused with synthetic cerebrospinal fluid and derivatized using fluorescein isothiocyanate (FITC). Laser-induced fluorescence (LIF) detection was employed. Good selectivity was obtained with a borate buffer (20 mM, pH 10.25). The whole procedure, including the washing step takes only 15 min. The conditions for derivatization and separation were optimized. The parameters for validation such as linearity, precision and detection limit are also reported. The results are consistent with those of HPLC but, as the sample volumes needed are only 1--5 nl, a much better time resolution can be obtained.

Animals↗
PubMed2001

Gel electrophoretic isolation, in the hundred microgram range, of recombinant SDS-syntaxin from sea urchin egg cortical vesicles.

Recombinant urchin syntaxin [Xa cut], electrophoresed at pH 9.0 (25 degrees C) or 10.2 (0 degrees C) in a discontinuous Tris-chloride-glycinate buffer system in the presence of 0.03% SDS in the catholyte, exhibits a multicomponent pattern in gels of a polyacrylamide concentration of 12% and 3% crosslinking. The position in the pattern of the syntaxin band was identified by reference to electropherograms of a previous study (P. Backlund, pers. comm.). The complexity of the protein composition of the preparation was reduced by selective stacking of proteins with mobilities greater than that of syntaxin. This provides a gel pattern consisting of two bands with mobilities close to that identified as syntaxin, as well as a minor, more slowly migrating, contaminant. The two major components are designated as S1 and S2, the latter being the larger species. In the absence of SDS, the preparation exhibits two pairs of protein components. Three of the proteins are charge isomers, i.e., of equal size, differing only in net charge, assumed to be forms of S1, while the fourth component is larger and is assumed to be S2. Aliquots of the preparation, containing 150 microg of protein were loaded on a cylindrical polyacrylamide gel of 18 mm diameter, and separated S1 and S2 were excised in a position defined by their characteristic values of relative mobility (Rf). Two or three gel slices, corresponding in Rf to S1 or S2, were pooled and loaded onto a Stacking Gel (5% polyacrylamide, 20% cross-linked) of 18 mm diameter, equipped with a collection chamber of 200 microL volume. The protein was electroeluted from the gel slices and concentrated into a stack by electrophoresis. The stack, marked by bromphenolblue, was allowed to migrate into the collection chamber, was collected and analyzed by protein assay and re-electrophoresis. Re-electrophoresis of S1 shows that it consists of at least three components. Recovered S1 constitutes 47% of the preparation, based on protein assay, S2 4%. S1, isolated from SDS-PAGE, exhibits an apparent Mr of 22.7 kDa, S2 one of 34.5 kDa, similar to the value of 32.6 kDa expected from the structure of syntaxin. The absence of S2 from the electroeluate re-electrophoresed at 0 degrees C and their molecular weight relationship suggest a proteolytic transformation of S2 to S1.

Animals↗
PubMed2001

[Expression of heme oxygenase-1 in neonatal rat cardiocytes induced by lipopolysaccharide].

To study the alterations of heme oxygenase-1 mRNA in neonatal rat cardiomyocytes (NRCMs) induced by lipopolysaccharide (LPS) and the role of heme oxygenase-1 (HO-1) in the LPS induced disorders of myocardium function, 10 (L, 6 h), 30 (M, 6 h), 50 micrograms/ml (H, 6 h) LPS and 10 micrograms/ml LPS + 10 mumol/ml Zn-protoporphyrin-IX (ZnPPIX; L + I, 6 h) and 10 mumol/ml ZnPPIX alone (I, 6 h) were added to the medium for a 6-hour culture of NRCMs, and 10 micrograms/ml LPS for 9 h (L, 9 h) and 18 h (L, 18 h) cultures. LDH release and MDA contents of the cells were measured. When NRCMs were collected, Trypan blue stain method was used to examine the mortality (the rate of Trypan blue uptake) of NRCMs. HO-1 mRNA expression was examined by Northern blot. The results showed that HO-1 mRNA expression of NRCMs increased gradually along with the increase of LPS concentration below the level of 30 micrograms/ml. When the final concentrations of LPS were 10 and 30 micrograms/ml, the HO-1 mRNA expression of NRCMs increased by 81.2% and 126.3% respectively compared with control. When the final concentration of LPS was 50 micrograms/ml, the HO-1 mRNA expression decreased to the level of 10 micrograms/ml group. When the final concentration was 10 micrograms/ml, the HO-1 mRNA expression increased gradually along with the culture time. After a 9- or 18-hour culture, the HO-1 mRNA expression of NRCMs increased by 93.6% and 105.8% respectively compared with control. Only when NRCMs had been cultured with 30, 50 micrograms/ml LPS and 10 micrograms/ml LPS + 10 mumol/ml ZnPPIX for 6 h and 10 micrograms/ml LPS for 18 h, the rate of Trypan blue stain uptake, MDA contents and LDH release significantly increased. With 10 micrograms/ml LPS alone and 10 mumol/ml ZnPPIX alone for 6 h, the above parameters were not significantly increased (P > 0.05). The results demonstrate that LPS induces HO-1 mRNA expression of NRCMs dose- and time-dependently to some extent. The inducible HO can protect NRCMs from injury and thus play an important role in pathogenesis of myocardium under LPS.

Animals↗