Biomedical subjects

G Li

Publications and source records attributed to G Li.

At least 37 records · Page 2Linked to original sources

PubMed2006

Observation of a near-threshold enhancement in the omega(phi) mass spectrum from the doubly OZI-suppressed decay J/psi-->gamma(omega)phi.

An enhancement near threshold is observed in the omega(phi) invariant mass spectrum from the doubly Okubo-Zweig-Iizuka-suppressed decays of J/psi-->gamma(omega)phi, based on a sample of 5.8 x 10(7) J/psi events collected with the BESII detector. A partial wave analysis shows that this enhancement favors JP=0+, and its mass and width are M=1812(+19)(-26)(stat)+/-18(syst) MeV/c2 and Gamma=105+/-20(stat)+/-28(syst) MeV/c2. The product branching fraction is determined to be B(J/psi-->gammaX)B(X-->omega(phi))=[2.61+/-0.27(stat)+/-0.65(syst)]x10(-4).

Journal Article↗

PubMed2006

Suprazero cooling conditions significantly influence subzero permeability parameters of mammalian ovarian tissue.

To model the cryobiological responses of cells and tissues, permeability characteristics are often measured at suprazero temperatures and the measured values are used to predict the responses at subzero temperatures. The purpose of the present study was to determine whether the rate of cooling from +25 to +4 degrees C influenced the measured water transport response of ovarian tissue at subzero temperatures in the presence or absence of cryoprotective agents (CPAs). Sections of freshly collected equine ovarian tissue were first cooled either at 40 degrees C/min or at 0.5 degrees C/min from 25 to 4 degrees C, and then cooled to subzero temperatures. A shape-independent differential scanning calorimeter (DSC) technique was used to measure the volumetric shrinkage during freezing of equine ovarian tissue sections. After ice was induced to form in the extracellular fluid within the specimen, the sample was frozen from the phase change temperature to -50 degrees C at 5 degrees C/min. Replicate samples were frozen in isotonic medium alone or in medium containing 0.85 M glycerol or 0.85 M dimethylsulfoxide. The water transport response of ovarian tissue samples cooled at 40 degrees C/min from 25 to 4 degrees C was significantly different (confidence level >95%) from that of tissue samples cooled at 0.5 degrees C/min, whether in the presence or absence of CPAs. We fitted a model of water transport to the experimentally-derived volumetric shrinkage data and determined the best-fit membrane permeability parameters (L(pg) and E(Lp)) of equine ovarian tissue during freezing. Subzero water transport parameters of ovarian tissue samples cooled at 0.5 degrees C/min from 25 to 4 degrees C ranged from: L(pg) = 0.06 to 0.73 microm/min.atm and E(Lp) = 6.1 to 20.5 kcal/mol. The corresponding parameters of samples cooled at 40 degrees C/min from 25 to 4 degrees C ranged from: L(pg) = 0.04 to 0.61 microm/min.atm and E(Lp) = 8.2 to 54.2 kcal/mol. Calculations made of the theoretical response of tissue at subzero temperatures suggest that the optimal cooling rates to cryopreserve ovarian tissue are significantly dependent upon suprazero cooling conditions.

Animals↗

PubMed2006

Subzero water transport characteristics and optimal rates of freezing rhesus monkey (Macaca mulatta) ovarian tissue.

The purpose of the present study was to examine the effect of two different suprazero (room temperature +25 degrees C to +4 degrees C) cooling conditions on the measured water transport response of primate (Macaca mulatta) ovarian tissue in the presence and absence of cryoprotective agents (CPAs). Freshly collected Macaca mulatta (rhesus monkey) ovarian tissue sections were cooled at either 0.5 degrees C/min or 40 degrees C/min from 25 to 4 degrees C. A shape independent differential scanning calorimeter (DSC) technique was then used to measure the volumetric shrinkage during freezing of ovarian tissue sections at a freezing rate of 5 degrees C/min in the presence and absence of three different CPAs (0.85 M glycerol, 0.85 M dimethylsulfoxide, and 0.85 M ethylene glycol). Thus, water transport during freezing of primate ovarian tissue was obtained at eight different conditions (i.e., at four different freezing media with two different suprazero cooling conditions). The water transport response of ovarian tissue cooled rapidly from 25 to 4 degrees C was significantly different (P < 0.01) than that of slow cooled tissue, in the freezing media without CPAs and with dimethylsulfoxide. However, the differences in the measured water transport response due to the imposed suprazero cooling conditions were reduced with the addition of glycerol and ethylene glycol (statistically different with P < 0.05). By fitting a model of water transport to the experimentally obtained volumetric shrinkage data the best-fit membrane permeability parameters (L(pg) and E(Lp)) were determined. The best-fit parameters of water transport in primate ovarian tissue sections ranged from: L(pg) = 0.7 to 0.15 microm/min-atm and E(Lp) = 22.1 to 32.1 kcal/mol (the goodness of fit parameter, R(2) > 0.96). These parameters suggest that the "optimal rates of cryopreservation" for ovarian tissue are significantly dependent upon suprazero cooling conditions and the choice of CPA.

Animals↗

PubMed2006

Needle shear wave driver for magnetic resonance elastography.

Magnetic resonance elastography (MRE) is capable of quantitatively depicting the mechanical properties of tissues in vivo. In contrast to mechanical excitation at the surface of the tissue, the method proposed in this study describes shear waves produced by an inserted needle. The results demonstrate that MRE performed with the needle driver provides shear stiffness estimates that correlate well with those obtained using mechanical testing. Comparisons between MRE acquisitions obtained with surface and needle drivers yielded similar results in general. However, the well-defined wave propagation pattern provided by the needle driver in a target region can reduce section orientation-related error in wavelength estimation that occurs with surface drivers in 2D MRE acquisitions. Preliminary testing of the device was performed on animals. This study demonstrates that the needle driver is an effective option that offers advantages over surface drivers for obtaining accurate stiffness estimates in targeted regions that are accessible by the needle.

Animals↗

PubMed2006

Verapamil modulates LPS-induced cytokine production via inhibition of NF-kappa B activation in the liver.

OBJECTIVE: To investigate the effect of verapamil on Lipopolysaccharide (LPS)-induced cytokines [tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and interleukin-10 (IL-10)] and nuclear factor kappa B (NF-kappa B) in the liver. METHODS AND MATERIALS: Adult male Sprague-Dawley rats were randomly divided into seven groups of eight rats each: control rats treated with saline (0.9 % NaCl); rats treated with saline and then challenged intraperitoneally with LPS (10 mg/kg); rats treated intraperitoneally with different levels of verapamil (1, 2.5, 5, 10 mg/kg) and then challenged with LPS (10 mg/kg); and rats treated only with verapamil (10 mg/kg). TNF-alpha, IL-6, IL-10 and NF-kappa B in the liver tissues were investigated as well as the serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) one hour after LPS injection. RESULTS: LPS alone stimulated production of TNF-alpha, IL-6 and IL-10, and activated NF-kappa B in the liver. Pretreatment with verapamil before LPS challenge reduced acute liver injury, down-regulated production of LPS-induced pro-inflammatory cytokines (TNF-alpha and IL-6), up-regulated production of anti-inflammatory cytokines (IL-10) and inhibited NF-kappa B activation in the liver in a dose-dependent manner. CONCLUSION: Verapamil can attenuate acute liver injury by down-regulating the production of TNF-alpha and IL-6 and up-regulating IL-10 in the liver, possibly via inhibition of NF-kappa B.

Animals↗

PubMed2006

Potent regulation of microglia-derived oxidative stress and dopaminergic neuron survival: substance P vs. dynorphin.

Unregulated microglial activation has been implicated as a pivotal factor contributing to Parkinson's disease. Using mesencephalic neuron-glia cultures, we address the novel possibility that peptides endogenous to the substantia nigra (SN), substance P and dynorphin (10(-13)-10(-14) M), are opposing mediators of microglial activation and consequent DA neurotoxicity. Here, we identify that substance P (10(-13)-10(-14) M) is selectively toxic to DA neurons in a microglia-dependent manner. Mechanistically, substance P (10(-13)-10(-14) M) activated microglial NADPH oxidase to produce extracellular superoxide and intracellular reactive oxygen species (ROS). Neuron-glia cultures from mice lacking a functional NADPH oxidase complex (PHOX-/-) were insensitive to substance P (10(-13)-10(-14) M) -induced loss of DA neuron function. Mixed glia cultures from (PHOX-/-) mice failed to show a significant increase in intracellular ROS in response to substance P compared with control cultures (PHOX+/+). Further, dynorphin (10(-14) M) inhibited substance P (10(-13) M) -induced loss of [3H] DA uptake. Here we demonstrate a tightly regulated mechanism governing microglia-derived oxidative stress, where the neuropeptide balance of dynorphin and substance P is critical to DA neuron survival.

Animals↗

PubMed2006

GLUT1 and p63 expression in endometrial intraepithelial and uterine serous papillary carcinoma.

AIMS: To analyse the expression patterns of GLUT1, p63 and p53 and the possible correlation between these markers in uterine serous papillary carcinoma (USPC) and endometrial intraepithelial carcinoma (EIC). METHODS AND RESULTS: Fourteen cases of USPC, 12 of which also showed EIC, were examined for GLUT1, p63 and p53 immunoreactivity. Four-micrometre sections from formalin-fixed paraffin-embedded tissue were immunostained using commercially available primary antibodies and Dako Envision Plus reagents for visualization. Membranous GLUT1 immunoreactivity was observed in all cases, including all 14 invasive tumours (100%) and 11 of 12 associated EICs (92%), and was confined to neoplastic cells. In USPC, staining tended to be strongest in superficial antistromal regions. p63 positivity was found in 8/14 (57%) USPCs and 9/12 (75%) associated EICs. In 11 cases p53 was overexpressed in both invasive USPC (11/14; 79%) and EIC (11/12; 92%). p53+ USPCs tended to be positive for p63, whereas p53- USPCs were also negative for p63. CONCLUSIONS: GLUT1 is expressed in the vast majority of USPC and EIC, suggesting a biological role during the early steps of carcinogenesis in endometrial serous neoplasms. GLUT1 expression may be induced by hypoxia-related as well as other mechanisms.

Biomarkers, Tumor↗

PubMed2006

Pseudomonas aeruginosa autoinducer modulates host cell responses through calcium signalling.

The opportunistic pathogen Pseudomonas aeruginosa utilizes a cell density-dependent signalling phenomenon known as quorum sensing (QS) to regulate several virulence factors needed for infection. Acylated homoserine lactones, or autoinducers, are the primary signal molecules that mediate QS in P. aeruginosa. The autoinducer N-3O-dodecanoyl-homoserine lactone (3O-C12) exerts effects on mammalian cells, including upregulation of pro-inflammatory mediators and induction of apoptosis. However, the mechanism(s) by which 3O-C12 affects mammalian cell responses is unknown. Here we report that 3O-C12 induces apoptosis and modulates the expression of immune mediators in murine fibroblasts and human vascular endothelial cells (HUVEC). The effects of 3O-C12 were accompanied by increases in cytosolic calcium levels that were mobilized from intracellular stores in the endoplasmic reticulum (ER). Calcium release was blocked by an inhibitor of phospholipase C, suggesting that release occurred through inositol triphosphate (IP3) receptors in the ER. Apoptosis, but not immunodulatory gene activation, was blocked when 3O-C12-exposed cells were co-incubated with inhibitors of calcium signalling. This study indicates that 3O-C12 can activate at least two independent signal transduction pathways in mammalian cells, one that involves increases in intracellular calcium levels and leads to apoptosis, and a second pathway that results in modulation of the inflammatory response.

4-Butyrolactone↗

PubMed2006

The visfatin gene is associated with glucose and lipid metabolism in a Chinese population.

AIMS: Visfatin is a newly discovered adipokine found in abundance in visceral fat. It lowers plasma glucose in humans and mice. In this study, we explored the relationships between the plasma level of visfatin and genetic single nucleotide polymorphisms (SNPs) and Type 2 diabetes mellitus (T2DM) and anthropometric and metabolic parameters in Chinese subjects. METHODS: Oral glucose tolerance tests (OGTT) and biochemical assays for plasma insulin, lipid profiles and serum visfatin were performed in 241 newly diagnosed T2DM patients, subjects with impaired glucose regulation (IGR), and normal glucose tolerant subjects more than 40 years of age. Genotyping for three SNP loci: -1535C/T, rs2058539 and rs10953502 were performed using the allele-specific real-time PCR method. RESULTS: Visfatin levels were similar in T2DM patients, IGR and normal glucose tolerant subjects. However, visfatin levels were significantly lower in obese than normal-weight subjects (13.66 +/- 0.87 vs. 15.46 +/- 0.47 ng/ml, P = 0.03). There was suggestively significant correlation between visfatin level and body mass index (r = -0.17 P = 0.07) and waist-hip ratio (r = 0.16 P = 0.08) in male subjects, but not in female subjects. Allele and common haplotype frequencies of the three SNP loci were similar in T2DM patients, IGR and normal glucose tolerant subjects. However, significant associations were found between these three SNP loci and plasma glucose concentration at 0 and 120 min during OGTT, the area under the response curve for plasma glucose, and triglyceride and total cholesterol levels. CONCLUSIONS: Serum visfatin levels may be related to visceral obesity in men, and the visfatin gene may account for variation of glucose and lipid parameters in Chinese subjects.

Adult↗

PubMed2006

Prevalence and genetic diversity of coronaviruses in bats from China.

Coronaviruses can infect a variety of animals including poultry, livestock, and humans and are currently classified into three groups. The interspecies transmissions of coronaviruses between different hosts form a complex ecosystem of which little is known. The outbreak of severe acute respiratory syndrome (SARS) and the recent identification of new coronaviruses have highlighted the necessity for further investigation of coronavirus ecology, in particular the role of bats and other wild animals. In this study, we sampled bat populations in 15 provinces of China and reveal that approximately 6.5% of the bats, from diverse species distributed throughout the region, harbor coronaviruses. Full genomes of four coronavirues from bats were sequenced and analyzed. Phylogenetic analyses of the spike, envelope, membrane, and nucleoprotein structural proteins and the two conserved replicase domains, putative RNA-dependent RNA polymerase and RNA helicase, revealed that bat coronaviruses cluster in three different groups: group 1, another group that includes all SARS and SARS-like coronaviruses (putative group 4), and an independent bat coronavirus group (putative group 5). Further genetic analyses showed that different species of bats maintain coronaviruses from different groups and that a single bat species from different geographic locations supports similar coronaviruses. Thus, the findings of this study suggest that bats may play an integral role in the ecology and evolution of coronaviruses.

Animals↗

PubMed2006

End-user survey for digital sensor characteristics: a pilot questionnaire study.

OBJECTIVE: To survey end-user opinions on dental digital sensor characteristics for the design of a new X-ray imaging sensor. MATERIALS AND METHODS: 100 questionnaires were sent out to dentists and dental radiologists. The questionnaire consisted of six parts related to dental sensors. A: Details about the respondent; B: Prioritization of most important aspects of digital sensors; C: Rating advantages and D: disadvantages of digital sensors; F: Dental features that need to be enhanced by digital sensors; G: End-user comments. RESULTS: Fifty-six questionnaires were returned. Contrast resolution and imaging time were assessed as the most and the least important aspects, respectively. Aspects considered as advantages by approximately 80% of respondents were: optimal contrast resolution, increased specificity, increased discrimination between diseased and healthy tissue, increased sensitivity, lower dose to the patient by more than 20%; as a disadvantage, increased patient dose was given. Dental features considered important by over 80% of the respondents were for intraoral radiographs: the visibility of caries, periapical, periodontal, and bone lesions; for panoramic radiographs: reduction of ghost images, image sharpness and bone. Bone and soft tissues on cephalograms and bone on temporomandibular joint (TMJ) tomograms were mentioned by over 70%. CONCLUSION: The most desired characteristic for a new sensor is contrast resolution. Dose saving is not considered as important unless it is more than 20%. Examination time is not a major issue. Caries, periapical and periodontal, and bone lesions for intraoral radiographs, reduction of ghost images, image sharpness and bone for panoramic radiographs were the most frequently mentioned dental features that should be enhanced by digital sensors.

Artifacts↗

PubMed2006

Effect of glycerol and cholesterol-loaded cyclodextrin on freezing-induced water loss in bovine spermatozoa.

Recent experimental data show that incubating bovine sperm with cholesterol-loaded cyclodextrin (CLC) before cryopreservation increases the percentages of motile and viable cells recovered after freezing and thawing, compared with control sperm. In the present study, we report the effect of incubating bovine sperm with CLC on the subzero water transport response and the membrane permeability parameters (reference membrane permeability (L(pg)) and activation energy (E(Lp))). Water transport data during freezing of bovine sperm cell suspensions were obtained at a cooling rate of 20 degrees C/min under three different conditions: 1. in the absence of cryoprotective agents (CPAs); 2. in the presence of 0.7 M glycerol; and 3. in the presence of 1.5 mg/ml CLC and 0.7 M glycerol. With previously published values, the bovine sperm cell was modeled as a cylinder of length 39.8 microm and radius 0.4 microm, with osmotically inactive cell volume (V(b)) of 0.61 V(o), where V(o) is the isotonic cell volume. By fitting a model of water transport to the experimentally obtained data, the best-fit water transport parameters (L(pg) and E(Lp)) were determined. The predicted best-fit permeability parameters ranged from L(pg) = 0.02 to 0.036 microm/min-atm and E(Lp) = 26.4 to 42.1 kcal/mol. These subzero water transport parameters are significantly different from the suprazero membrane permeability values (obtained in the absence of extracellular ice) reported in the literature. Calculations made of the theoretical response of bovine spermatozoa at subzero temperatures suggest that the optimal cooling rate to cryopreserve bovine spermatozoa is 45-60 degrees C/min, agreeing quite closely with experimentally determined rates of freezing bovine spermatozoa.

Animals↗

PubMed2006

Electrolytic degradation of biorefractory organics and ammonia in leachate from bioreactor landfill.

Electrochemical oxidation was applied to treat the effluent from bioreactor landfill with leachate recirculation, characterised as poor biodegradability and high NH3-N concentration. In this study, the effluent was electrolysed in a batch reactor with Ti/TiO2-IrO2-RuO2 anode and stainless steel cathode. The oxidation of dissolved organic matter (DOM) during electrolysis was evaluated based on the evolution of molecular weight grade, hydrophilic fractionation (humic acid, fulvic acid and hydrophilic fractions), specific ultraviolet absorbance (SUVA254) and AOX. The impact of the initial NH3-N concentration on the oxidation was discussed. The results showed that at a current density of 100 mA/cm2, electrolysis time of 1.5 h and electrode gap of 1 cm, NH3-N with an initial concentration of 1.2 g/L could be completely eliminated and 56% of COD with an initial concentration of 1.2 g/L could be removed, which illustrated that the electrolysis-produced chlorine preferentially oxidised ammonia. The electrolysis mainly resulted in the degradation of humic substances and other high molecular DOM, followed by the increase of BOD/COD ratio and decline of SUVA254 of the leachate. The current efficiencies for COD and ammonia oxidation gradually decreased during the electrolysis, with the latter obviously higher than the former. At the optimal electrolysis time of 1.5 h, NH3-N could be totally removed and the BOD/COD ratio could be enhanced to 0.3, which was also favourable to control the AOX at a reasonable level.

Ammonia↗

PubMed2005

Observation of a resonance in Chi(1835) in J/psi --> gammapi+ pi- eta-.

The decay channel J/psi --> gamma(pi)(+)pi(-)eta is analyzed using a sample of 5.8 x 10(7) J/psi events collected with the BESII detector. A resonance, the Chi(1835), is observed in the pi(+)pi(-)eta invariant-mass spectrum with a statistical significance of 7.7 sigma. A fit with a Breit-Wigner function yields a mass M = 1833.7 +/- 6.1(stat) +/- 2.7(syst) MeV/c(2), a width Tau = 67.7 +/- 20.3(stat) +/- 7.7(syst) MeV/c(2), and a product branching fraction B(J/psi --> gammaChi) . B(Chi --> pi(+)pi(-)eta) = [2.2 +/- 0.4(stat) +/- 0.4(syst)] x 10(-4). The mass and width of the Chi(1835) are not compatible with any known meson resonance. Its properties are consistent with expectations for the state that produces the strong pp mass threshold enhancement observed in the J/psi --> gammapp process at BESII.

Journal Article↗

PubMed2005

Serum cholesterol and risk of Alzheimer disease: a community-based cohort study.

OBJECTIVES: To examine the association of serum total cholesterol (TC) and high density lipoprotein (HDL) levels and subsequent incidence of dementia and Alzheimer disease (AD) in a population-based cohort study. METHODS: A cohort of cognitively intact persons, aged 65 and older, was randomly selected from Group Health Cooperative (GHC), a large health maintenance organization, and was assessed biennially for dementia. Premorbid levels of TC and HDL were obtained from a computerized clinical laboratory database at GHC. Cox proportional hazards regression was used to calculate hazard ratios (HR, 95% CI) for dementia and AD associated with quartiles of TC and HDL levels. RESULTS: Of the 2,356 eligible participants, 2,141 had at least one serum TC measure prior to the initial enrollment. Using the lowest TC quartiles as the reference group, the HR in the highest TC quartiles was not significantly elevated for dementia (1.16, 0.81 to 1.67) or for AD (1.00, 0.61 to 1.62) after adjusting for age, sex, education, baseline cognition, vascular comorbidities, body mass index, and lipid-lowering agent use. Serum HDL showed a similar lack of significant association with risk of dementia or AD. Models that included the presence of one or more APOE-epsilon4 alleles showed a typical association of epsilon4 with AD risk. This association was not materially modified by inclusion of TC level. CONCLUSION: The data do not support an association between serum total cholesterol or high density lipoprotein in late life and subsequent risk of dementia or Alzheimer disease (AD). The increased risk of AD with APOE-epsilon4 is probably not mediated by serum total cholesterol levels.

Age Factors↗

PubMed2005

Hypothalamic pro-opiomelanocortin gene delivery ameliorates obesity and glucose intolerance in aged rats.

AIMS/HYPOTHESIS: Age-related obesity is associated with impaired hypothalamic pro-opiomelanocortin (Pomc) gene expression. We assessed whether overproduction of POMC in the hypothalamus ameliorates age-related obesity in rats. METHODS: Recombinant adeno-associated virus (rAAV) encoding Pomc (rAAV-Pomc) or control vector was delivered bilaterally into the basomedial hypothalamus of aged obese rats with coordinates targeting the arcuate nucleus. Energy balance, glucose metabolism, brown adipose tissue thermogenesis and mRNA levels of hypothalamic neuropeptides and melanocortin receptors were assessed. RESULTS: Forty-two days after Pomc gene delivery, hypothalamic Pomc expression increased 12-fold while agouti-related protein and neuropeptide Y mRNA levels remained unchanged. Using a punch technique, we detected the highest Pomc RNA level in the arcuate nucleus. Pomc overexpression reduced food consumption from day 10 after vector injection, but this anorexic effect abated by day 30. In contrast, there was a steady decrease in body weight without apparent attenuation. Pomc gene delivery decreased visceral adiposity and induced uncoupling protein 1 in brown adipose tissue in aged rats. Serum NEFA and triglyceride levels were also diminished by rAAV-Pomc treatment. Improved glucose metabolism and insulin sensitivity were observed on day 36 but not day 20 after Pomc gene delivery. The expression of hypothalamic melanocortin 3 and 4 receptor decreased by 17% and 25%, respectively in rAAV-Pomc rats. CONCLUSIONS/INTERPRETATION: This study demonstrates that targeted Pomc gene therapy in the hypothalamus reduces body weight and visceral adiposity, and improves glucose and fat metabolism in aged obese rats. Thus long-term activation of the central melanocortin system may be a viable strategy to combat age-related obesity and diabetes.

Adipose Tissue, Brown↗

PubMed2005

A novel method for determination of collagen orientation in cartilage by Fourier transform infrared imaging spectroscopy (FT-IRIS).

OBJECTIVE: The orientation of collagen molecules is an important determinant of their functionality in connective tissues. The objective of the current study is to establish a method to determine the alignment of collagen molecules in histological sections of cartilage by polarized Fourier transform infrared imaging spectroscopy (FT-IRIS), a method based on molecular vibrations. METHODS: Polarized FT-IRIS data obtained from highly oriented tendon collagen were utilized to calibrate the derived spectral parameters. The ratio of the integrated areas of the collagen amide I/II absorbances was used as an indicator of collagen orientation. These data were then applied to FT-IRIS analysis of the orientation of collagen molecules in equine articular cartilage, in equine repair cartilage after microfracture treatment, and in human osteoarthritic cartilage. Polarized light microscopy (PLM), the most frequently utilized technique to evaluate collagen fibril orientation in histological sections, was performed on picrosirius red-stained sections for comparison. RESULTS AND CONCLUSION: Thicknesses of each zone of normal equine cartilage (calculated based on differences in collagen orientation) were equivalent as determined by PLM and FT-IRIS. Comparable outcomes were obtained from the PLM and FT-IRIS analyses of repair and osteoarthritis tissues, whereby similar zonal variations in collagen orientation were apparent for the two methods. However, the PLM images of human osteoarthritic cartilage showed less obvious zonal discrimination and orientation compared to the FT-IRIS images, possibly attributable to the FT-IRIS method detecting molecular orientation changes prior to their manifestation at the microscopic level.

Animals↗

PubMed2005

Reaction of pyridoxamine with malondialdehyde: mechanism of inhibition of formation of advanced lipoxidation end-products.

Advanced glycation end products (AGEs) and advanced lipoxidation end products (ALEs) are implicated in many age-related chronic diseases and in protein aging. Recent studies suggest that pyridoxamine (PM) is an efficient AGEs/ALEs inhibitor in various biological systems. Because malondialdehyde (MDA) is an important intermediate in the formation of ALEs during lipid peroxidation, the purpose of this study is to determine whether PM can trap MDA directly and thereby prevent ALEs formation. PM reacted readily with MDA under physiological conditions. Within 6 h, a 1-pyridoxamino-propenal adduct derived from reaction of equimolar PM + MDA was detected. A 1-amino-3-iminopropene complex and a dihydropyridine-pyridinium complex were also identified after 7 d incubation. PM also greatly inhibited the lipofuscin-like fluorescence formation induced by MDA reaction with bovine serum albumin (BSA). Our results showed clearly that PM inhibited the formation of ALEs by trapping MDA directly under physiological condition, and provide insight into the mechanism of action of PM in protecting proteins against carbonyl stress.

Animals↗