Biomedical subjects

Xi Lin

Publications and source records attributed to Xi Lin.

36 records · Page 2Linked to original sources

PubMed2004

Phencyclidine-induced changes in rat cortical gene expression identified by microarray analysis: implications for schizophrenia.

Acute phencyclidine induces schizophrenia-like symptoms in healthy humans and psychotic episodes in schizophrenics. Although phencyclidine is known as a N-methyl d-aspartate receptor antagonist (NMDA-R), the molecular events underlying the behavioral symptoms remain largely unknown. Statistical analysis of oligonucleotide microarray data was used to identify phencyclidine-induced alterations in rat cortical gene expression. Acute phencyclidine produced a statistically significant change in 477 genes in rat prefrontal cortex (PFC), a brain area associated with cognitive dysfunction in schizophrenics. Real-time quantitative PCR (RTQ-PCR) confirmed a subset of these changes ranging from -59% to 255% (smallest confirmation: -19%). Subsequent time-course and dose-response studies using RTQ-PCR confirmed and extended the original microarray results. At the molecular level, genes altered by phencyclidine are related to diverse biological processes including stress, inflammatory response, growth and development, neural plasticity and signal transduction. Further analysis, aimed at assessing the relevance of our results to schizophrenia, revealed dysregulation of genes related to: (i) thalamocortical projections, (ii) neurotransmission and neuromodulation, (iii) thyroid hormone activity, (iv) oligodendrocyte linage, (v) brain lipid metabolism, (vi) sleep architecture and (viii) the velocardiofacial syndrome.

Animals↗

PubMed2004

At what scale should microarray data be analyzed?

INTRODUCTION: The hybridization intensities derived from microarray experiments, for example Affymetrix's MAS5 signals, are very often transformed in one way or another before statistical models are fitted. The motivation for performing transformation is usually to satisfy the model assumptions such as normality and homogeneity in variance. Generally speaking, two types of strategies are often applied to microarray data depending on the analysis need: correlation analysis where all the gene intensities on the array are considered simultaneously, and gene-by-gene ANOVA where each gene is analyzed individually. AIM: We investigate the distributional properties of the Affymetrix GeneChip signal data under the two scenarios, focusing on the impact of analyzing the data at an inappropriate scale. METHODS: The Box-Cox type of transformation is first investigated for the strategy of pooling genes. The commonly used log-transformation is particularly applied for comparison purposes. For the scenario where analysis is on a gene-by-gene basis, the model assumptions such as normality are explored. The impact of using a wrong scale is illustrated by log-transformation and quartic-root transformation. RESULTS: When all the genes on the array are considered together, the dependent relationship between the expression and its variation level can be satisfactorily removed by Box-Cox transformation. When genes are analyzed individually, the distributional properties of the intensities are shown to be gene dependent. Derivation and simulation show that some loss of power is incurred when a wrong scale is used, but due to the robustness of the t-test, the loss is acceptable when the fold-change is not very large.

Algorithms↗

PubMed2004

[The quantitative analysis of protein particles of erythrocyte membrane from Duchenne muscular dystrophy patients and the gene carriers].

OBJECTIVE: To study the changes of the intramembrane protein particles of erythrocyte from Duchenne muscular dystrophy (DMD) patients and the gene carriers and to explore the pathogenesis of DMD and the diagnostic value of erythrocyte freeze-fracture technology. METHODS: The fixed erythrocyte mass was treated to form replica membrane by means of the freeze-fracture technology. Then the replica membrane was observed and a picture was taken under electron microscope. The protein particles of extracellular face(EF) and protoplasmic face(PF) per square were counted. The statistical comparative analysis was performed. RESULTS: The protein particle counts of EF face and PF face of erythrocyte membrane from DMD patients and DMD carriers decreased obviously in comparison with the normal control group (P<0.001). CONCLUSION: The erythrocyte freeze-fracture electron microscopic technology may serve as a method for accessory examination of diagnosing DMD patients and a method for detecting DMD carriers. This investigation material supplies reliable evidence for the theory of the systemic membrane defect of DMD.

Erythrocyte Membrane↗

PubMed2004

[Electron microscopic study on Trichomonas vaginalis adhering to and phagocytizing male genitourinary epithelial cells].

OBJECTIVE: To observe Trichomonas vaginalis (T. vaginalis) adhering to and phagocytizing male genitourinary epithelial cells in order to study the pathogenetic mechanism of male trichomoniasis. METHODS: Cultured T. vaginalis bodies were incubated with male genitourinary epithelial cells, and then the ultrastructure was observed with transmission electron microscopy. RESULTS: T. vaginalis adhered to epithelial cells like amoeba, and formed pseudopodium or surface invagination surrounding or nibbling other parts of the epithelial cytoplasm. CONCLUSIONS: T. vaginalis has the speciality of adhering to and phagocytizing to male genitourinary epithelial cells. Genitourinary epithelial cells may be injured directly by the phagocytosis of T. vaginalis. Attention has to be paid to the correlation.

Animals↗

PubMed2003

Connexins 26 and 30 are co-assembled to form gap junctions in the cochlea of mice.

The importance of connexins (Cxs) in the cochlear functions has been indicated by the finding that mutations in connexin genes cause a large proportion of sensorineural deafness cases. However, functional roles of connexins in the cochlea are still unclear. In this study, we compared the relative expression levels of 16 different subtypes of mouse connexins in the cochlea. cDNA macroarray hybridizations identified four most prominently expressed connexins (listed in descending order): Cxs 26, 29, 30, and 43. Two of these connexins (Cx26 and Cx30), both belonging to the beta-group, were investigated for their molecular assemblies in the cochlea. Co-immunostaining showed expressions of Cxs 26 and 30 in the same gap junction plaques and their co-assembly was confirmed by co-immunoprecipitation of proteins extracted from the cochlear tissues. The heterologous molecular assembly of connexins is expected to produce gap junctions with biophysical characteristics appropriate for maintaining ionic homeostasis in the cochlea.

Animals↗

PubMed2003

Aspirin selectively augmented N-methyl-D-aspartate types of glutamate responses in cultured spiral ganglion neurons of mice.

Aspirin is commonly used to study tinnitus in animal models because of its ability to induce tinnitus in human subjects. However, the mechanism by which aspirin affects auditory function remains unclear. To investigate the effect of aspirin on the cochlear neurotransmission, we studied its interactions with major types of membrane channels and receptors regulating the excitability of cultured type I spiral ganglion (SG) neurons. Results showed that aspirin had little effect on voltage-gated sodium and potassium currents of SG neurons. In contrast, it selectively potentiated the N-methyl-D-aspartate (NMDA) subtype of the glutamate responses in SG neurons while showing little effect on the alpha-amino-3-hydroxy-5-methylisozazole-4-propionic acid and kainate types of glutamate responses. The aspirin-induced current in the presence of NMDA increased in a dose-dependent manner with a half maximal concentration of 2.2 mM, and it was blocked by NMDA receptor antagonist 2-amino-5-phosphonopentanoic acid or Mg(2+). These in vitro results suggested that aspirin could interfere with the glutamatergic neurotransmission in the cochlea by selectively amplifying NMDA-mediated responses.

Animals↗

PubMed2003

Liver trauma: experience in 348 cases.

Liver trauma, the main cause of death in patients suffering abdominal injury, remains an unresolved problem, especially in its most severe forms. The objective of this study was to probe effective surgical procedures and improve the outcome for patients with severe hepatic injury. A retrospective study of 348 patients with hepatic trauma seen in our institution during the past 12 years was carried out. Of these 348 patients, 259 (74.4%) underwent surgery. To manage severe liver trauma (American Association for the Surgery of Trauma grade III to grade V), procedures such as packing of the laceration with omentum, hepatectomy or direct control of bleeding vessels within the liver substance by means of the Pringle maneuver, selective hepatic artery ligation, retrohepatic caval repair with total hepatic vascular occlusion, and perihepatic packing were selected and combined based on the specific injury. In the 259 patients treated operatively, the survival rate was 86.9% (225/259); and 15 of 40 with retrohepatic venous injury (RHVI) were cured with the maximum blood transfusion of 60 units. In 42 patients treated by perihepatic packing, the bleeding was stopped in 20 of 25 (80%) with RHVI and in 14 of 17 (82%) without such injury ( p > 0.75). The percentage of failure of nonoperative management was 17.2% (17/99); and it was 46.7% (14/30) in patients with grade III-V injury. Death occurred in 3 (50%) of 6 failures of grade IV-V injury. The overall mortality rate was 11.8% (41/348), and 51% of the deaths were due to exsanguination. The results suggest that severe hepatic injuries, especially grade IV-V injuries, usually require surgical intervention; reasonable surgical procedures based on classification of liver trauma and combined application of techniques can increase the survival rate; and perihepatic packing is effective in dealing with RHVI.

Adolescent↗

PubMed2003

Optical recordings of Ca2+ signaling activities from identified inner ear cells in cochlear slices and hemicochleae.

One of the major obstacles hindering the progress of studies on mammalian cochlear physiology is the inaccessibility of inner ear cells located in a complex structure of the bony labyrinth. We describe here a technique to record cellular fluorescent signals from any identified inner ear cells in cochlear slices and hemicochleae. Cochlear slices were obtained from postnatal rats (P0-P7) before the cochlea completely ossify, and hemicochleae were cut from older animals (P7-adult). Individual inner ear cells were visually identified using infrared differential interference contrast or oblique illumination optics. Techniques were developed for either bulk-loading cells or loading selected single cells with Ca(2+) indicator dyes, and for maintaining functional viability of cochlear slices/hemicochleae for recordings. Robust and reliable responses of ligand-gated receptors were recorded from individual inner ear cells (e.g. hair cells, spiral ganglion neurons etc.) for at least 24 h after slices/hemicochleae were cut by an oscillating tissue slicer. The technique described here allowed direct observations of [Ca(2+)](i) activities from multiple cells simultaneously in situ, thus providing a feasible way to study the intercellular communication or networking activities from identified cells in the inner ear.

Action Potentials↗

PubMed2003

Changes in kinetics of carnitine palmitoyltransferase in liver and skeletal muscle of dogs (Canis familiaris) throughout growth and development.

This study was conducted to investigate developmental changes in the kinetics of carnitine palmitoyltransferase (CPT) within hepatic and skeletal muscle tissues of the canine species. Carnitine concentrations, CPT activity and the apparent K(m) for carnitine were measured in tissue homogenates from dogs in six age categories: newborn; 24-h-old; 3-, 6- and 9-wk-old; and adult. Hepatic CPT activity was low at birth, increased by 100% during the suckling period (P < 0.05) and then declined after weaning to adult levels. In contrast, CPT activity in muscle continued to increase with age, reaching adult levels after 9 wk. Congruent with CPT activity, nearly identical concentration profiles of liver and muscle acylcarnitines were observed. The apparent K(m) of hepatic CPT for carnitine also paralleled the increase in CPT activity during the suckling period; however, free and total liver carnitine concentrations declined by 50% during this time (P < 0.05). Beginning at 3 wk of age, the hepatic concentration of free carnitine was at or below the apparent K(m) of CPT for carnitine. A similar relationship existed in muscle of young dogs, but in adults, the free carnitine concentration was markedly increased and exceeded the apparent K(m) by 5-fold. Collectively, we infer that fatty acid oxidation capacity increases rapidly after birth in the canine, after ontogenic increases in CPT activity. Furthermore, based on the relatively low tissue carnitine concentrations when compared with the apparent carnitine K(m) of CPT, we suggest that carnitine may have an important role in the regulation of fatty acid oxidation and that increased dietary carnitine may improve fatty acid oxidative capacity in developing dogs.

Animals↗

PubMed2003

[The dosage of SDS when extracting membranous labyrinth proteins].

OBJECTIVE: To determine the appropriate dosage of SDS when extracting membranous labyrinth proteins. METHOD: The yield of proteins extracted with various amounts of SDS were determined by BCA method, and the components of the extracted proteins were analyzed by SDS-PAGE. RESULT: The amount of proteins extracted with 0.1% SDS is less than that with 0.23%, 1% or 2% SDS, meanwhile it shows less bands than the other and the corresponding bands are stained weaker. 0.23% SDS is less efficiently than 1% and 2% SDS in solubilizing proteins. There is no significant difference between 2% and 1% SDS in yield of proteins, while 2% SDS accompanies a higher ratio of detergent to protein. CONCLUSION: 1% SDS is solutions is relatively suitable for extracting membranous labyrinth proteins extensively while the ratio of detergent to protein is from 5 to 6.

Animals↗

PubMed2003

[Effect of Helicobacter pylori infection on iron status among preschool children].

OBJECTIVE: To explore the relationship between Helicobacter pylori (Hp) infection and iron status using serum ferritin (SF) as a marker for total iron and to identify the related factors of iron nutritional status among preschool children. METHODS: By cluster sampling, we recruited 475 preschool children aged 2 to 7 years. A structured questionnaire and diet form were sent to the parents of these children to obtain related information about the socioeconomic level and dietary intakes. After collecting blood samples, the following indexes were measured. Hp IgG antibodies were measured with a dot enzyme-linked immunoassay; hemoglobin, Hct, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), red blood cell distribution width index (RDW) with automatic Complete Blood Count; SF with an immunoradiometric assay. Stool Hp antigen and occult bleeding were measured with ELISA among individuals who were Hp seropositive. Hp status was defined as positive when both serum and stool antigen tests were positive, Hp status was defined as negative when serum antigen test was negative; 24-hour weighting and recording methods were used to dietary survey for three days in May and December 2001, respectively, dietary intakes including energy, protein and micronutrient were calculated using nursery school nutrition software and evaluated by Chinese Dietary Reference Intakes (DRIs). Mann-Whitney test was used to compare mean ranks of SF in Hp-positive and Hp-negative children. To obtain an adjusted estimate of the impact of Hp infection on SF, a multivariate analysis of covariance was done to evaluate the different level of SF between Hp infected and non-infected status. The relationship between iron deficiency and gender, age, socioeconomic condition, iron intake, and calcium intake was assessed by univariate analysis. An unconditional multivariate logistic regression analysis was also performed. Iron deficiency status was dichotomized and placed as the dependent variable. Hp infection status was incorporated together with possible confounding factors as independent variables in a final logistic regression model. All the data were managed by EPI Info 5.01a and analyzed by SAS (Version 6.12). RESULTS: Totally 64 children were diagnosed as Hp-positive and 305 as Hp-negative. Mann-Whitney test and multivariate analysis of covariance both showed that SF concentration was significantly lower in Hp infected individuals than non-infected individuals. Adjusted mean level and 95% confidence interval of SF in infected and non-infected children was 23.62 microg/L (7.13 microg/L-78.26 microg/L), 33.48 microg/L (10.28 microg/L-109.06 microg/L), respectively. The relationship between Hp infection and iron deficiency status persisted in logistic regression analysis after adjusting for possible confounding factors (OR: 7.95; 95% CI 2.56 - 24.67). CONCLUSION: Iron nutritional status was reduced in Hp infected preschool children. Hp infection appears to be an independent risk factor or an added stressor on iron status among preschool children.

Antibodies, Viral↗

PubMed2002

Interaction between mutant ataxin-1 and PQBP-1 affects transcription and cell death.

PQBP-1 was isolated on the basis of its interaction with polyglutamine tracts. In this study, using in vitro and in vivo assays, we show that the association between ataxin-1 and PQBP-1 is positively influenced by expanded polyglutamine sequences. In cell lines, interaction between the two molecules induces apoptotic cell death. As a possible mechanism underlying this phenomenon, we found that mutant ataxin-1 enhances binding of PQBP-1 to the C-terminal domain of RNA polymerase II large subunit (Pol II). This reduces the level of phosphorylated Pol II and transcription. Our results suggest the involvement of PQBP-1 in the pathology of spinocerebellar ataxia type 1 (SCA1) and support the idea that modified transcription underlies polyglutamine-mediated pathology.

Aged↗

PubMed2002

Expression patterns of aquaporins in the inner ear: evidence for concerted actions of multiple types of aquaporins to facilitate water transport in the cochlea.

Water transport between the perilymph and endolymph is important in regulations of volume and osmotic pressure of the inner ear labyrinth. It is now known that expression of water channels (aquaporins or AQPs) in the cell membrane dramatically increases the ability of water to cross epithelial cells. The aims of the current study were to investigate the cellular localization of AQPs by immunolabeling, and to study the developmental expression and relative abundance of various subtypes of AQPs. We report here that AQP3, AQP7 and AQP9 were expressed in the inner ear. Specific subtypes of AQPs were found in discrete regions expressed by both epithelial cells and fibrocytes in cochlear and vestibular organs. Semi-quantitative measurements showed that AQP4 and AQP1 were the two most abundantly expressed AQP subtypes in the inner ear, and their expressions were dramatically upregulated during development. These data showed a highly localized and largely non-overlapping distribution pattern for different subtypes of AQPs in the inner ear, suggesting the existence of regional subtype-specific water transport pathways, and global regulation of water transport in the inner ear may require concerted actions of multiple types of AQPs.

Aging↗

PubMed2002

Prenylcysteine carboxylmethyltransferase is essential for the earliest stages of liver development in mice.

BACKGROUND & AIMS: Liver development, regeneration, and oncogenesis involve signaling events mediated by a number of proteins, such as ras and the related small guanosine triphosphatases. Many of these signaling proteins carry unique CAAX motifs, which are processed by prenylcysteine carboxylmethyltransferase (PCCMT), among several other enzymes. We investigated the function of Pccmt during mouse liver development to better understand the embryonic lethality of the null mutation. METHODS: Generation of Pccmt-null mice by embryonic stem cell technology, molecular and histologic analysis of Pccmt-null embryos, and foregut endoderm cultures. RESULTS: Pccmt-null embryos die in utero with severe anemia and extensive apoptosis at embryonic day 10.5. We show that deletion of Pccmt leads to a dramatic delay in albumin induction, an early and definitive marker for hepatocyte development. In tissue explant cultures supplemented with fibroblast growth factor (FGF), albumin induction remained impaired. We found that hepatocyte precursors in Pccmt-null embryos failed to invade the septum transversum, resulting in liver agenesis. CONCLUSIONS: PCCMT is essential for several stages of hepatic induction, consistent with its role in modifying proteins required to transduce signals, such as FGF, that have been shown to promote liver specification and early growth.

Anemia↗

PubMed2002

Medium-chain fatty acids but not L-carnitine accelerate the kinetics of [14C]triacylglycerol utilization by colostrum-deprived newborn pigs.

The effect of L-carnitine on in vivo fatty acid utilization was determined using colostrum-deprived newborn piglets fed emulsified triglycerides (TG) composed of [1-14C]octanoate (tri-8:0) or [1-14C]octadecanoate (tri-18:1). A soy protein-based liquid diet devoid of L-carnitine was fed piglets for 1 d to allow development of fatty acid-metabolizing enzymes and intestinal fat digestion and absorption before assessment of in vivo fat utilization. The radiolabeled TG were fed in isoenergetic amounts (97.7 kJ/kg(0.75)), with or without L-carnitine (1 mmol/kg(0.75)) as 30% (v/v) emulsions, using polyoxyethylene sorbitan monooleate as an emulsifier. Expired CO(2) was quantified and specific radioactivity (Bq/micromol) was determined at 20-min intervals over 24 h. The rate (mmol ATP.kg(-0.75).min(-1)) and extent (mol ATP/kg(0.75)) of TG oxidative utilization (i.e., composite of digestion, absorption and oxidation) were calculated from the kinetics of 14CO(2) expiration. The maximal rate and extent of tri-8:0 oxidation were three and fourfold greater than those of tri-18:1, respectively (P < 0.001), and tri-18:1 delayed the time to reach 10 and 50% of maximal oxidation rate by 1.2 and 1.9 h (P < 0.01, respectively), regardless of supplemental carnitine. Collectively, these findings quantify the accelerated oxidation of medium-chain vs. long-chain triglycerides, but fail to support a need for supplemental carnitine to maximize fat oxidation in colostrum-deprived piglets.

Animals↗

PubMed2002

Severe hepatic trauma: surgical strategies.

OBJECTIVE: To probe into effective surgical procedures and improve the outcome of treatment for patients with severe hepatic injury. METHODS: A retrospective study involving 113 patients with severe hepatic trauma (AAST grade IV and V) during the past 12 years was carried out. Ninety-eight patients underwent surgical treatment. Surgical interventions including hepatectomy or direct control of bleeding vessels by finger fracture technique with Pringle maneuver, selective ligation of hepatic artery, retrohepatic caval repair with total hepatic vascular occlusion, and perihepatic packing were mainly used. RESULTS: In the 98 patients treated operatively, the survival rate was 69.4% (68/98). Among 40 patients with juxtahepatic venous injury (JHVI), 15 were cured with the maximum blood transfusion of 12,000 ml. Eight cases of Grade IV injury treated nonoperatively were cured. The percentage of failure of nonoperative management was 42.9% (6/14). The overall mortality rate was 32.7% (37/113), and 57% of the deaths were due to exsanguination. CONCLUSIONS: Reasonable surgical procedures based on classification of hepatic injuries can increase the survival rate of severe liver trauma. Accurate perihepatic packing is effective in dealing with JHVI.

Adolescent↗

PubMed2000

Epidemiological characteristics and preventive strategies for fall injury.

OBJECTIVE: To elucidate the epidemiological characteristics and to define some preventive strategies for fall injury (FI). METHODS: The medical records of patients admitted following a fall from a certain height between August 1996 and July 1997 were analyzed retrospectively. RESULTS: A total of 138 patients were assessed, with a mortality of 31.2%. The male-to-female ratio was 3.5:1. The persons between 20 and 59 years old were the main victims (81.8%), of which 52.2% were related with their work altitude. The remaining adults fall because of, accidents in daily life, suicide attempts, drug abuse, alcohol, or criminal behavior. There were significant differences between the death group and the survival group in the Revised Trauma Score (RTS) and the Injury Severity Score (ISS) value (P<0.05 and P<0.01, respectively). Six children fall from balconies, open windows or roofs. There were significant differences for the height of fall and RTS value in aged group than those in children, adolescents, and adults (P<0.001, 0.005, 0.05; and P<0.05, 0.01, 0.05, respectively). The mortality of FI was significantly correlated to the height of fall (r=0.897, P<0.005). CONCLUSIONS: Male adults are the main victims, especially the workers at high altitudes. The mortality of FI is significantly correlated to the height of fall. The preventive strategies developed through analyzing the risk factors of fall in different age groups might reduce the injuries and deaths following fall.

Journal Article↗

PubMedDate not supplied

Optimization and validation of small quantity RNA profiling for identifying TNF responses in cultured human vascular endothelial cells.

INTRODUCTION: Affymetrix oligonucleotide microarrays are widely used in basic and applied research (Lander, E.S., (1999). Array of hope. Nature Genetics 21, 3-4; Lockhart, D.J. & Winzeler, E.A. (2000) Genomics, gene expression and DNA arrays. Nature 405, 827-836.) The need for a significant amount of starting RNA has limited its use in applications where the amount of RNA is limiting, such as with Laser Captured Microdissection (LCM), small biopsies, or peripheral blood in rodent models. To overcome this limitation, various RNA amplification and labeling methods have been described, however, further optimization and validation of these methods are needed. METHODS: Here we reported using the Arcturus technology to optimize amplification and labeling of small amounts of RNA for Affymetrix microarray studies. We assessed the technical feasibility and variation introduced by differences in starting RNA quantity and differences in technical performance by microarray hybridization. RESULTS: We demonstrated that the current approach is reliable to amplify as little as 40 ng total RNA, and it is suitable for Affymetrix studies yielding satisfactory quantitative chip performance. We also showed that differences in labeling methods contribute more to variation than the differences in starting RNA quantity per se. As a model, we studied the well-documented TNF-induced inflammatory responses in cultured human vascular endothelial cells. We were able to recapitulate the TNF-induced responses using small RNA sample profiling.

Algorithms↗