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Biomedical subjects

H Le

Publications and source records attributed to H Le.

At least 19 recordsLinked to original sources
PubMed2006

Development of a human mitochondria-focused cDNA microarray (hMitChip) and validation in skeletal muscle cells: implications for pharmaco- and mitogenomics.

Mitochondrial research has influenced our understanding of human evolution, physiology and pathophysiology. Mitochondria, intracellular organelles widely known as 'energy factories' of the cell, also play fundamental roles in intermediary metabolism, steroid hormone and heme biosyntheses, calcium signaling, generation of radical oxygen species, and apoptosis. Mitochondria possess a distinct DNA (mitochondrial DNA); yet, the vast majority of mitochondrial proteins are encoded by the nuclear DNA. Mitochondria-related genetic defects have been described in a variety of mostly rare, often fatal, primary mitochondrial disorders; furthermore, they are increasingly reported in association with many common morbid conditions, such as cancer, obesity, diabetes and neurodegenerative disorders, although their role remains unclear. This study describes the creation of a human mitochondria-focused cDNA microarray (hMitChip) and its validation in human skeletal muscle cells treated with glucocorticoids. We suggest that hMitChip is a reliable and novel tool that will prove useful for systematically studying the contribution of mitochondrial genomics to human health and disease.

Adolescent↗
PubMed2003

Nutrient removal by the integrated use of high rate algal ponds and macrophyte systems in China.

High Rate Algal Ponds (HRAP) were operated at pilot scale to investigate the performance of HRAP under the temperate climate conditions of Shanghai, China. The results indicated that the HRAP gave good efficiency for nutrient removal, especially during summer. With a retention time of 4 or 8d according to the season, the annual average removal efficiencies for COD, NH4-N and PO4-P were 50%, 87% and 40%, respectively. The multi-factor linear models showed the relationships between nutrient removal efficiency and influencing factors. Using a macrophyte pond to separate algae from HRAP can achieve concentrations of COD, TP and TKN in the effluent at around 50 mg/L, 1.5 mg/L and 5 mg/L respectively.

Biodegradation, Environmental↗
PubMed2001

Early graft function after pediatric liver transplantation: comparison between in situ split liver grafts and living-related liver grafts.

BACKGROUND: The systematic application of living-related and cadaveric, in situ split-liver transplantation has helped to alleviate the critical shortage of suitable-sized, pediatric donors. Undoubtedly, both techniques are beneficial and advantageous; however, the superiority of either graft source has not been demonstrated directly. Because of the potential living-donor risks, we reserve the living donor as the last graft option for pediatric recipients awaiting liver transplantation. Inasmuch as no direct comparison between these two graft types has been performed, we sought to perform a comparative analysis of the functional outcomes of left lateral segmental grafts procured from these donor sources to determine whether differences do exist. METHODS: A retrospective analysis of all liver transplants performed at a single institution between February 1984 and January 1999 was undertaken. Only pediatric (<18 years) recipients of left lateral segmental grafts procured from either living-related (LRD) or cadaveric, in situ split-liver (SLD) donors were included. A detailed analysis of preoperative, intraoperative, and postoperative variables was undertaken. Survival was estimated using the Kaplan-Meier method, and comparison of variables between groups was undertaken using the t test of Wilcoxon rank sum test. RESULTS: There were no significant differences in the preoperative variables between the 39 recipients of SLD grafts and 34 recipients of LRD grafts. The donors did differ significantly in mean age, ABO blood group matching, and preoperative liver function testing. Postoperative liver function testing revealed significant early differences in aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, prothrombin time, and alkaline phosphatase, with grafts from LRD performing better than those from SLD. SLD grafts also had significantly longer ischemia times and a higher incidence of graft loss owing to primary nonfunction and technical complications (9 vs. 2, P<0.05). However, six of these graft losses in the SLD group were because of technical or immunologic causes, which, theoretically, should not differ between the two groups. Furthermore, these graft losses did not negatively impact early patient survival as most patients were successfully rescued with retransplantation (30-day actuarial survival, 97.1% SLD vs. 94.1% LRD, P=0.745). In the surviving grafts, the early differences in liver function variables normalized. CONCLUSIONS: Inherent differences in both donor sources exist and account for differences seen in preoperative and intraoperative variables. Segmental grafts from LRD clearly performed better in the first week after transplantation as demonstrated by lower liver function variables and less graft loss to primary nonfunction. However, the intermediate function (7-30 days) of both grafts did not differ, and the early graft losses did not translate into patient death. Although minimal living-donor morbidity was seen in this series, the use of this donor type still carries a finite risk. We therefore will continue to use SLD as the primary graft source for pediatric patients awaiting liver transplantation.

Adult↗
PubMed2001

Proinflammatory and regulatory cytokine production associated with innate and adaptive immune responses in children with autism spectrum disorders and developmental regression.

We determined innate and adaptive immune responses in children with developmental regression and autism spectrum disorders (ASD, N=71), developmentally normal siblings (N=23), and controls (N=17). With lipopolysaccharide (LPS), a stimulant for innate immunity, peripheral blood mononuclear cells (PBMCs) from 59/71 (83.1%) ASD patients produced >2 SD above the control mean (CM) values of TNF-alpha, IL-1beta, and/or IL-6 produced by control PBMCs. ASD PBMCs produced higher levels of proinflammatory/counter-regulatory cytokines without stimuli than controls. With stimulants of phytohemagglutinin (PHA), tetanus, IL-12p70, and IL-18, PBMCs from 47.9% to 60% of ASD patients produced >2 SD above the CM values of TNF-alpha depending on stimulants. Our results indicate excessive innate immune responses in a number of ASD children that may be most evident in TNF-alpha production.

Adaptation, Physiological↗
PubMed2001

Evidence of dysregulated cytokine production by sinus lavage and peripheral blood mononuclear cells in patients with treatment-resistant chronic rhinosinusitis.

BACKGROUND: Treatment-resistant chronic rhinosinusitis (CRS) imposes a clinical challenge. Its pathogenesis may be associated with dysregulated immune/inflammatory responses in the sinus. OBJECTIVE: To evaluate production of types 1 and 2 T cytokines (interferon gamma [IFN-gamma] and interleukin [IL] 5/IL-4, respectively) and regulatory/inflammatory cytokines (IL-10, IL-12, and IL-18) by sinus lavage (SL) cells and peripheral blood mononuclear cells (PBMCs) in patients with treatment-resistant CRS. METHODS: Sample SL cells and PBMCs obtained from 19 patients with treatment-resistant CRS were cultured with or without stimuli, and cytokine levels in the supernatant were measured using enzyme-linked immunosorbent assay. Control PBMC samples were obtained from 26 children. RESULTS: Chronic otitis media was found in 15 patients. Neutrophils and/or epithelial cells were dominant in SL cells. IFN-gamma, IL-12p40, and IL-10 (>100 pg/mL) were detected in SL cell cultures from 12, 9, and 8 patients, respectively. Production of IL-12p40 and IL-18 by SL cells correlated positively with phytohemagglutinin and IL-12p70 stimuli. In 12 patients, we detected IL-18 (>100 pg/mL) in SL cell cultures without stimuli, whereas PBMCs produced little IL-18, irrespective of stimuli. There was no correlation between cytokine levels produced by SL cells and PBMCs, except for IL-12p40 produced using IL-18. Decreased IFN-gamma production by PBMCs was observed in 6 patients with CRS compared with controls, but 4 of them had elevated IFN-gamma production by SL cells. Production of IL-12p40 by PBMCs was higher in 10 patients with CRS than in controls, and 7 of these patients had lower IL-10 production, resulting in an increased IL-12p40/IL-10 ratio. CONCLUSIONS: There is a role for locally produced regulatory cytokines in IFN-gamma production in the sinus in patients with treatment-resistant CRS. However, aberrant cytokine production patterns by PBMCs can be detected at high frequency in these patients, indicating that this can be used as a prognostic marker for patients with CRS.

Adolescent↗
PubMed2001

[Relationship between maternal nutritional stetus and intrauterine growth retardation with neonatal visual development disorder].

OBJECTIVE: To investigate the relationship between the maternal nutritional stetus and the occurrence of intrauterine growth retardation (IUGR) with neonatal visual development disorder. METHODS: Sixty pregnant women closed to expected date of confinement were randomly divided into 2 groups: IUGR and normal control group, each were with 30 cases. Eight kinds of nutritional foods taken by the pregnant women were investigated and scored. The vitamin A concentrations of maternal and umbilical blood were measured with fluorometer method. The concentrations of iron, copper and zinc in maternal and umbilical blood were detected by spectrophotometer. The results of examination with Flash-visual evoked potentials (F-VEP) were recorded by an experienced technician in neonates at 3-7 days after birth and 10 months after follow-up. RESULTS: Compared with the normal control, the IUGR group had taken less eggs, animal liver and fat pork during pregnancy (P < 0.05), had remarkable lower concentrations of vitamin A and iron in maternal and umbilical blood (P < 0.01), and had a lower umbilical blood zinc concentration (P < 0.05). Meanwhile, neonates with IUGR had obvious delay of the latent period of F-VEP's main positive component (P100) (P < 0.05) and an attenuation of the P100 with when it was measured at 3-7 days after birth and at 10th month after fellow-up (P < 0.01). CONCLUSION: The decreased intake of foods rich in vitamin A, iron, zinc and other nutritional components was closely correlated with IUGR occurrence and resulted in retardation of neonate visal development.

Evoked Potentials, Visual↗
PubMed2000

Plant initiation factor 3 subunit composition resembles mammalian initiation factor 3 and has a novel subunit.

Eukaryotic initiation factor 3 (eIF3) is a multisubunit complex that is required for binding of mRNA to 40 S ribosomal subunits, stabilization of ternary complex binding to 40 S subunits, and dissociation of 40 and 60 S subunits. These functions and the complex nature of eIF3 suggest multiple interactions with many components of the translational machinery. Recently, the subunits of mammalian and Saccharomyces cerevisiae eIF3 were identified, and substantial differences in the subunit composition of mammalian and S. cerevisiae were observed. Mammalian eIF3 consists of 11 nonidentical subunits, whereas S. cerevisiae eIF3 consists of up to eight nonidentical subunits. Only five of the subunits of mammalian and S. cerevisiae are shared in common, and these five subunits comprise a "core" complex in S. cerevisiae. eIF3 from wheat consists of at least 10 subunits, but their relationship to either the mammalian or S. cerevisiae eIF3 subunits is unknown. Peptide sequences derived from purified wheat eIF3 subunits were used to correlate each subunit with mammalian and/or S. cerevisiae subunits. The peptide sequences were also used to identify Arabidopsis thaliana cDNAs for each of the eIF3 subunits. We report seven new cDNAs for A. thaliana eIF3 subunits. A. thaliana eIF3 was purified and characterized to confirm that the subunit composition and activity of wheat and A. thaliana eIF3 were similar. We report that plant eIF3 closely resembles the subunit composition of mammalian eIF3, having 10 out of 11 subunits in common. Further, we find a novel subunit in the plant eIF3 complex not present in either mammalian or S. cerevisiae eIF3. These results suggest that plant and mammalian eIF3 evolved similarly, whereas S. cerevisiae has diverged.

Amino Acid Sequence↗
PubMed2000

The phosphorylation state of poly(A)-binding protein specifies its binding to poly(A) RNA and its interaction with eukaryotic initiation factor (eIF) 4F, eIFiso4F, and eIF4B.

The poly(A)-binding protein (PABP) interacts with the eukaryotic initiation factor (eIF) 4G (or eIFiso4G), the large subunit of eIF4F (or eIFiso4F) to promote translation initiation. In plants, PABP also interacts with eIF4B, a factor that assists eIF4F function. PABP is a phosphoprotein, although the function of its phosphorylation has not been previously investigated. In this study, we have purified the phosphorylated and hypophosphorylated isoforms of PABP from wheat to examine whether its phosphorylation state affects its binding to poly(A) RNA and its interaction with eIF4G, eIFiso4G, or eIF4B. Phosphorylated PABP exhibited cooperative binding to poly(A) RNA even under non-stoichiometric binding conditions, whereas multiple molecules of hypophosphorylated PABP bound to poly(A) RNA only after free poly(A) RNA was no longer available. Together, phosphorylated and hypophosphorylated PABP exhibited synergistic binding. eIF4B interacted with PABP in a phosphorylation state-specific manner; native eIF4B increased the RNA binding activity specifically of phosphorylated PABP and was greater than 14-fold more effective than was recombinant eIF4B, whereas eIF4F promoted the cooperative binding of hypophosphorylated PABP. These data suggest that the phosphorylation state of PABP specifies the type of binding to poly(A) RNA and its interaction with its partner proteins.

Binding Sites↗
PubMed2000

Detection of shape changes in biological features.

The question of analysing shape changes over time, such as during growth and during the progress of disease, is an important fundamental issue for many applications. Recent mathematical developments in the understanding of the detailed structure of shape spaces have made possible the quantitative study of shape variation. In this paper, we combine the classical multidimensional scaling technique with knowledge of the geometry of shape spaces to examine the role played by the geodesics in shape spaces. We present some promising early results answering questions about shape changes over time.

Anatomy↗
PubMed2000

Induction of apoptotic cell death in peripheral blood mononuclear and polymorphonuclear cells by an oral bacterium, Fusobacterium nucleatum.

It is largely unknown why a variety of bacteria present in the oral cavity are capable of establishing themselves in the periodontal pockets of nonimmunocompromised individuals in the presence of competent immune effector cells. In this paper we present evidence for the immunosuppressive role of Fusobacterium nucleatum, a gram-negative oral bacterium which plays an important role in the generation of periodontal disease. Our studies indicate that the immunosuppressive role of F. nucleatum is largely due to the ability of this organism to induce apoptotic cell death in peripheral blood mononuclear cells (PBMCs) and in polymorphonuclear cells (PMNs). F. nucleatum treatment induced apoptosis of PBMCs and PMNs as assessed by an increase in subdiploid DNA content determined by DNA fragmentation and terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end-labeling assays. The ability of F. nucleatum to induce apoptosis was abolished by either heat treatment or proteinase digestion but was retained after formaldehyde treatment, suggesting that a heat-labile surface protein component is responsible for bacterium-mediated cell apoptosis. The data also indicated that F. nucleatum-induced cell apoptosis requires activation of caspases and is protected by NF-kappaB. Possible mechanisms of F. nucleatum's role in the pathogenesis of periodontal disease are discussed.

Apoptosis↗
PubMed2000

DNA testing for haemochromatosis: diagnostic, predictive and screening implications.

Since 1996, the identification of the HFE gene has enabled DNA testing for hereditary haemochromatosis (HH). The range of DNA testing available includes: (1) diagnostic, (2) predictive (also called presymptomatic testing) and (3) screening. Access to DNA testing has been facilitated by an Australian Medicare rebate, the first available for genetic disorders. Despite the availability of HFE DNA testing in HH, it remains necessary to interpret results in the context of the clinical picture. Traditional markers based on phenotype (transferrin ferritinsaturation, and liver biopsy) are still required in some circumstances. We report our experience with HFE DNA testing using a semi-automated approach, which allows multiplexing for the two common mutations (C282Y and H63D). Screening a cohort of beta-thalassaemia major and sickle cell anaemia patients of predominantly Mediterranean origin showed that these individuals do not have the common C282Y mutation. This excluded C282Y as a factor in the pathogenesis of iron overload in these haemoglobinopathies. It also showed that the C282Y mutation is of limited value when investigating HH in certain ethnic groups. An Australian family studied illustrated the relative contribution of C282Y and H63D in iron overload. A recently reported third mutation (S65C) in the HFE gene was detected in a low frequency in the populations tested.

Aged↗
PubMed1998

HSP101 functions as a specific translational regulatory protein whose activity is regulated by nutrient status.

The 5' leader (Omega) of tobacco mosaic viral RNA functions as a translational enhancer. Sequence analysis of a 102-kD protein, identified previously as a specific Omega RNA-binding protein, revealed homology to the HSP101/HSP104/ClpB family of heat shock proteins and its expression in yeast complemented a thermotolerance defect caused by a deletion of the HSP104 gene. Up to a 50-fold increase in the translation of Omega-luc, but not luc mRNA was observed in yeast expressing the tobacco HSP101 whereas Omega failed to enhance translation in the absence of HSP101. Therefore, HSP101 and Omega comprise a two-component translational regulatory mechanism that can be recapitulated in yeast. Analysis of HSP101 function in yeast translation mutants suggested that the initiation factor (eIF) 3 and specifically one (TIF4632) of the two eIF4G proteins were required for the HSP101-mediated enhancement. The RNA-binding and translational regulatory activities of HSP101 were inactive in respiring cells or in cells subject to nutrient limitation, but its thermotolerance function remained unaffected. This is the first identification of a protein required for specific translational enhancement of capped mRNAs, the first report of a translational regulatory function for any heat-shock protein, and the first functional distinction between the two eIF4G proteins present in eukaryotes.

Amino Acid Sequence↗
PubMed1998

The phosphorylation state of the wheat translation initiation factors eIF4B, eIF4A, and eIF2 is differentially regulated during seed development and germination.

The translation initiation factors (eIF) 4B and eIF2 are phosphoproteins whose phosphorylation state differs between mature seed and leaves. We examined the isoforms of eIF4B and the alpha and beta subunits of eIF2 during the development and germination of wheat seed to determine whether the differences in their phosphorylation state are because of tissue-specific regulation or occur concomitant with changes in protein synthetic activity during development. eIF2alpha underwent phosphorylation through several intermediate isoforms that correlated with the increase and subsequent reduction in protein synthetic activity characteristic of seed development. eIF2beta and eIF4B, present as highly phosphorylated isoforms during early seed development, underwent dephosphorylation during late development. eIF4B was rapidly phosphorylated within 20 h of germination, whereas eIF2alpha did not undergo dephosphorylation until 48-60 h of growth. A third factor, eIF4A, was predominantly nonphosphorylated throughout most of seed development and germination. These observations suggest that the phosphorylation state of eIF2alpha, eIF2beta, and eIF4B is developmentally regulated in a way that correlates with the changes in protein synthetic activity but that some differences were also observed.

Electrophoresis, Gel, Two-Dimensional↗
PubMed1998

Analysis of translation elongation factors from wheat during development and following heat shock.

Translational activity in plants undergoes rapid changes during developmental stages such as seed formation and germination, and during abiotic stresses such as heat shock, hypoxia and wounding. We examined the protein levels and isoelectric state of two components of the translation machinery, elongation factor (EF) 1 alpha and 2, to determine their roles in the regulation of translation. We found that the apparent protein levels of EF1 alpha increase relative to the EF2 levels which decline slightly during the development of the wheat seed. During germination, high levels of these factors are present in seedling tissues known to be actively engaged in translation; however, no differences in isoelectric state were observed during germination. As an example of abiotic stress, heat shock had little impact on the apparent levels of EF1 alpha or EF2 present in wheat leaves, nor were changes in the number or levels of isoforms observed.

Germination↗
PubMed1998

Expression and ligand binding assays of soluble cytokine receptor-immunoglobulin fusion proteins.

We have developed a cloning vector for the expression of type I cytokine receptor, NO, extracellular domain (ECD)-mouse IgG1 Fc fusion proteins. The vector has a versatile polylinker that allows in-frame cloning of the receptor ECD with the mouse IgG1 sequence to encode a receptor ECD-IgG1 fusion construct. The receptor-IgG1 fusion proteins are transiently expressed in useful amounts following transfection of the expression vector into COS7 cells and G418 selection. The mouse IgG1 portion of the fusion protein provides a universal handle for purification on an affinity matrix and detection by anti-mouse IgG antibodies in ELISA or Western blot formats. The expressed receptor ECD-IgG1 fusion proteins bind their cognate ligands. In order to demonstrate that the fusion proteins have similar ligand binding affinities as the native receptors, the affinity constants (Kd) for EPOR, TNFR, IL-4R, and IL-6R-IgG1 fusion proteins were measured by surface plasmon resonance and shown to be in good agreement with published values. The TNFR-IgG1 fusion protein was employed in a demonstration of a novel ELISA format for detecting cytokine receptor binding to cytokine.

Amino Acid Sequence↗
PubMed1998

Capillary electrophoresis: new technology for DNA diagnostics.

New innovations in the diagnostic laboratory achieve their full potential when they can be automated. Increasingly molecular biology (DNA) techniques are being utilised in traditional pathology disciplines, as well as the more recent ones of cytogenetics and molecular genetics. Molecular biology was first exploited for diagnostic purposes when Southern blotting became established. However the time-consuming nature of the methodology, as well as the skills required, made it difficult for Southern blotting to be used routinely in the service laboratory. Subsequently the invention of PCR facilitated the approach to DNA diagnostics. Today PCR in commercial or home-made kits is used for a range of procedures. The steps required to amplify DNA with PCR can also be fully automated. However the analysis of PCR products, which frequently requires slab gel electrophoresis and toxic chemicals or radioisotopes for visualisation, remains difficult to automate. An alternative way for analysing PCR products is now available through capillary electrophoresis. With this technique, automation can be extended to sample loading, electrophoresis and data analysis. The use of toxic chemicals or radioisotopes can be avoided.

Chromosome Mapping↗