Search PubMed⌕ Search

Biomedical subjects

J Liu

Publications and source records attributed to J Liu.

At least 127 records · Page 7Linked to original sources
PubMed2005

Flow across the gastro-esophageal junction: lessons from the sleeve sensor on the nature of anti-reflux barrier.

The principles of fluid flow are critical to the understanding of flow across the gastro-esophageal (GE) junction or gastro-esophageal reflux. The mechanism by which sleeve sensor measures lower esophageal sphincter (LES) pressure is also based on the principle of fluid flow across the GE junction and can provide important insights into the nature of anti-reflux barrier. We present arguments regarding the role of the length of LES, intra-abdominal length of the LES, flap valve at the GE junction and the angle of His on the strength of anti-reflux barrier. Our conclusion is that in the presence of normal anatomy of the GE junction (absence of hiatus hernia) the pressure at the GE junction is the most important determinant of the strength of anti-reflux barrier.

Animals↗
PubMed2005

Oesophageal wall stress and muscle hypertrophy in high amplitude oesophageal contractions.

Excessive wall stress is a known stimulus for muscle growth. We recently reported a thickened muscularis propria in patients with high amplitude oesophageal contractions (HAEC). The goal of this study was to determine oesophageal wall stress in normal subjects and patients with HAEC. A manometry catheter equipped with a high frequency ultrasound (US) transducer was used to record pressure and US images simultaneously in 10 healthy subjects and 11 patients with HAEC. Recordings were obtained at 2 and 10 cm above the lower oesophageal sphincter during water swallows. The changes in circumferential wall stress during oesophageal contraction in both groups are relatively small because of an increase in the wall thickness-to-radius ratio during contraction. Patients show a greater muscle thickness than normal subjects at rest and at the peak of contraction. The wall stress in patients is elevated at the 2 cm but not at the 10-cm level as compared to normal subjects. Wall strain is not different between the two groups. Increase in wall thickness during oesophageal contraction maintains low wall stress. A greater wall stress in patients with HAEC may be a stimulus for the increased wall thickness.

Adult↗
PubMed2005

A novel locus for autosomal dominant hereditary gingival fibromatosis, GINGF3, maps to chromosome 2p22.3-p23.3.

Hereditary gingival fibromatosis (HGF) is a rare, benign disorder characterized by slowly progressive fibrous overgrowth of the gingiva. To date, two loci have been mapped in familial cases with autosomal dominant non-syndromic HGF: GINGF (MIM 135300) on chromosome 2p21-p22 and GINGF2 (MIM 605544) on chromosome 5q13-q22. Of the two loci, only SOS1 (son of sevenless one, MIM 182530) gene underlying GINGF locus has been identified. Ascertainment of a large Chinese family has allowed the mapping of a novel locus to 2p22.3-p23.3, GINGF3. Haplotype construction and analysis localized the new locus to an 11.4-cM interval between markers D2S2221 (telomeric) and D2S1788 (centromeric). The maximum two-point limit of detection (LOD) score of 3.45 (theta=0) and multipoint LOD score of 5.00 for marker D2S390 strongly supported linkage to this region. Thus, this genetic interval is distal to and does not overlap with the previously described locus, GINGF, on 2p21-p22.

Asian People↗
PubMed2005

Pioglitazone initiation and subsequent hospitalization for congestive heart failure.

AIMS: Thiazolidinediones (TZD) have been associated with an expansion in plasma volume and the development of peripheral oedema. A recent study reported an association between the use of TZDs and development of congestive heart failure (CHF). The objective of this study was to determine if short-term use of pioglitazone, a TZD, is associated with increased risk of admission to hospital because of CHF in a well-characterized, community-based cohort of Type 2 diabetic patients without prevalent CHF. METHODS: A cohort study of all patients in the Kaiser Permanente Medical Care Program with Type 2 diabetes (Kaiser Permanente Northern California Diabetes Registry) who initiated any diabetes pharmacotherapy (n = 23 440) between October 1999 and November 2001. Only patients initiating single new therapies ('new users') were included to reduce confounding and create mutually exclusive exposure groups. We constructed Cox proportional hazards models (with sulphonylureas initiators specified as the reference group) to evaluate the impact of initiating new diabetes therapies on time-to-incident admission to hospital because of CHF, defined by primary hospital discharge diagnosis. RESULTS: Patients initiated pioglitazone (15.2%), sulphonylureas (25.3%), metformin (50.9%), and insulin (8.6%) alone, or as additions to pre-existing or maintained therapies. Three hundred and twenty admissions for CHF were observed during the follow-up (mean 10.2 months) after drug initiation. Relative to patients initiating sulphonylureas, there were no significant increases in the incidence of hospitalization for CHF in those initiating pioglitazone [hazard ratio (HR) = 1.28; 95% confidence interval (CI): 0.85-1.92] after adjusting for demographic, behavioural and clinical factors. There was a significantly higher incidence among those initiating insulin (HR = 1.56; 95% CI: 1.00-2.45) and lower incidence among those initiating metformin (HR = 0.70; 95% CI: 0.49-0.99). CONCLUSIONS: This study of patients with Type 2 diabetes failed to find evidence that short-term pioglitazone use was associated with an elevated risk of hospitalization for CHF relative to the standard, first-line diabetes therapy.

Aged↗
PubMed2005

Prevalence of Parkinson's disease in Sydney.

OBJECTIVE: To examine the prevalence of Parkinson's disease (PD) in Bankstown, Sydney, using the same methodology as a previous study in Randwick, Sydney, Australia (1998-1999). PARTICIPANTS AND METHODS: Twenty census districts (CDs) for the Bankstown local government area were randomly selected. Research personnel door-knocked every household within the CDs to locate people aged > or =55 years. A structured questionnaire (containing four screening questions for PD) was administered to those agreeing to participate. Screened positive participants were invited to come for a clinical examination. This is a continuation of the previous study and data have been combined. RESULTS: Combining data for Bankstown and Randwick gave 1028 participants; crude prevalence, 780 per 100,000 (CI: 546-1077). In Bankstown, there were 501 participants aged > or =55 years (response rate 70%); 135 were screened positive with 101 (74.8%) agreeing to a clinical examination. The prevalence of PD in the Bankstown community was 3.4% (17 of 501) (95% CI: 1.98-5.43) for those aged > or =55 years; crude prevalence 776 per 100,000 (CI: 452-1241). CONCLUSION: The combined results of two Sydney studies appear to indicate that Sydney has one of the highest prevalence estimates of PD in developed countries.

Aged↗
PubMed2005

Allosteric functioning of dimeric class C G-protein-coupled receptors.

Whereas most membrane receptors are oligomeric entities, G-protein-coupled receptors have long been thought to function as monomers. Within the last 15 years, accumulating data have indicated that G-protein-coupled receptors can form dimers or even higher ordered oligomers, but the general functional significance of this phenomena is not yet clear. Among the large G-protein-coupled receptor family, class C receptors represent a well-recognized example of constitutive dimers, both subunits being linked, in most cases, by a disulfide bridge. In this review article, we show that class C G-protein-coupled receptors are multidomain proteins and highlight the importance of their dimerization for activation. We illustrate several consequences of this in terms of specific functional properties and drug development.

Animals↗
PubMed2005

Neurobehavioral effects of treatment for opiate withdrawal.

A partially randomised, controlled trial was performed to test the hypothesis that opiate exposed infants treated with diluted tincture of opium (DTO) and phenobarbital would have better neurobehavioral scores than infants treated with DTO alone. Compared with those treated with DTO alone (n = 15), infants treated with DTO and phenobarbital (n = 17) were more interactive, had smoother movements, were easier to handle, and less stressed. Dual treatment results in improved neurobehavioral organisation during the first three weeks of life, which may indicate a more rapid recovery from opiate withdrawal.

Analgesics, Opioid↗
PubMed2005

Rose (Rosa rugosa)-flower extract increases the activities of antioxidant enzymes and their gene expression and reduces lipid peroxidation.

The effects of rose-flower extract on antioxidant enzymes were studied. The activities of catalase (CAT) and glutathione peroxidase (GPx) in 9-month-old senescence-accelerated mice (SAM mice) were lower than those in 6-month-old SAM mice. Therefore, 9-month-old SAM mice were the most appropriate targets for treatment with the rose-flower extract. The activities of CAT and GPx in SAM mice treated with rose-flower extract showed a marked increase in whole blood and liver. At the same time, the gene-expression level of CAT and GPx was upregulated in the liver, while malondialdehyde content in liver and brain decreased. Male SAM mice were more sensitive than female SAM mice. The mean and the longest lifespan of SAM mice were longer after treatment with rose-flower extract.

Aging↗
PubMed2005

The discharged excess sludge treated by Oligochaeta.

To overcome unstable worm growth, a new worm-reactor was developed for oligochaete growth. The bench scale of this worm-reactor was used to treat the discharged excess sludge from a pilot activated sludge system, and experiments were carried out to investigate the sludge reduction induced by Oligochaeta. Due to difficult getting free-swimming worms such as Aeolosoma hemprichicii and Nais elinguis, Tubifex tubifex was thus selected and inoculated in Reactor 1 at the start-up phase except the control reactor (Reactor 2). Tubifex occurred in Reactor 1 throughout the operation period after its inoculation, and mainly attached on the carriers and aggregated on the bottom of the worm-reactor. Free-swimming worms such as Aeolosoma hemprichicii, Nais elinguis, and Aulophorus furcatus were found in both reactors since the 35th day. Microscopic investigation showed that these free-swimming worms naturally produced in the pilot activated sludge system, and entered into both reactors along the discharged sludge. Results clearly showed that the average sludge reduction in Reactor 1 was 59%, much higher than that in the control. The characteristics of sludge settling was improved by worm growth, but was not too much. High ammonia nitrogen concentration in influent sludge was toxic to worms, and then inhibited worm growth. Both the total inorganic nitrogen and phosphorus releases into effluent sludge were observed in Reactor 1, but such increases were not heavy.

Animals↗
PubMed2004

Steady-state fluorescence study on release of camptothecin from agar hydrogel.

The slow drug release processes from agar hydrogel were studied by steady-state fluorescence (SSF) measurement. An anticancer drug, camptothecin (CPT), was used as the release drug and the fluorescence probe for the real-time monitoring of the release processes by measuring the fluorescence intensity of the probe. The release kinetics of CPT at different temperatures was investigated. The Fickian diffusion model was adopted to fit the results and a good linear relationship could be observed between the logarithmic release fraction and the releasing time. The diffusion coefficients (D) at these conditions were thus obtained from the slopes of the fitting curves. By plotting D against temperature, the diffusion coefficient of CPT was found to obey the Arrhenius relation and the activation energy was then obtained to be 70.6 kJ mol(-1).

Agar↗
PubMed2004

Repeated dosing of botulinum toxin type A for upper limb spasticity following stroke.

The authors evaluated the long-term efficacy and safety of botulinum toxin type A (BTX-A) in poststroke spasticity patients who completed a 12-week placebo-controlled study and received multiple open-label treatments with 200 to 240 U BTX-A for 42 weeks. Significant and sustained improvements were observed for Disability Assessment and Ashworth scores. Adverse events were generally mild. This extension of a double-blind study demonstrates that repeated treatments of BTX-A significantly improve function and tone in spasticity.

Activities of Daily Living↗
PubMed2004

The Hawaiian Archipelago: a microbial diversity hotspot.

The Hawaiian Archipelago is a "biodiversity hotspot" where significant endemism among eukaryotes has evolved through geographic isolation and local topography. To address the absence of corresponding region-wide data on Hawaii's microbiota, we compiled the first 16S SSU rDNA clone libraries and cultivated bacteria from five Hawaiian lakes, an anchialine pool, and the Lō'ihi submarine volcano. These sites offer diverse niches over approximately 5000 m elevation and approximately 1150 nautical miles. Each site hosted a distinct prokaryotic community dominated by Bacteria. Cloned sequences fell into 158 groups from 18 Bacteria phyla, while seven were unassigned and two belonged in the Euryarchaeota. Only seven operational taxonomic units (each OTU comprised sequences that shared > or =97% sequence identity) occurred in more than one site. Pure bacterial cultures from all sites fell into 155 groups (each group comprised pure cultures that shared > or =97% 16S SSU rDNA sequence identity) from 10 Bacteria phyla; 15 Proteobacteria and Firmicutes were cultivated from more than one site. One hundred OTUs (60%) and 52 (33.3%) cultures shared <97% 16S SSU rDNA sequence identity with published sequences. Community structure reflected habitat chemistry; most delta-Proteobacteria occurred in anoxic and sulfidic waters of one lake, while beta-Proteobacteria were cultivated exclusively from fresh or brackish waters. Novel sequences that affiliate with an Antarctic-specific clade of Deinococci, and Candidate Divisions TM7 and BRC1, extend the geographic ranges of these phyla. Globally and locally remote, as well as physically and chemically diverse, Hawaiian aquatic habitats provide unique niches for the evolution of novel communities and microorganisms.

Bacteria↗
PubMed2004

Effects of dexamethasone, vitamin A and vitamin D3 on DSP-PP mRNA expression in rat tooth organ culture.

Vitamin A, 1,25-dihydroxyvitamin D3 and dexamethasone are well-characterized hydrophobic molecules whose biological actions are mediated via different members of the nuclear hormone receptor family. We report here their actions on tooth formation at the molecular level. We have tested the effects of these compounds on osteopontin (OPN), dentin sialoprotein (DSP-PP), and collagen type I expression in pre-mineralization and mineralization stage rat tooth organ cultures which mirror in vivo developmental patterns. These proteins are all believed to participate in the mineralization of dentin. 1,25-Dihydroxyvitamin D3 up-regulated OPN, but had no effect on DSP-PP mRNA expression. Vitamin A up-regulated DSP-PP expression as did dexamethasone. Dexamethasone also up-regulated collagen type I expression. Our results suggest that 1,25-dihydroxyvitamin D3 does not modulate dentin mineralization by directly affecting DSP-PP expression. Vitamin A likely contributes to dentin mineralization by up-regulating DSP-PP expression. Finally, the up-regulation of DSP-PP expression in tooth germ cultures treated with dexamethasone suggests that its application to patient's dental pulp might promote increased extracellular matrix synthesis and mineralization in the pulp and may explain the narrowing of the dental pulp cavity in patients undergoing long-term dexamethasone administration.

Animals↗
PubMed2004

Ultralong single-wall carbon nanotubes.

Since the discovery of carbon nanotubes in 1991 by Iijima, there has been great interest in creating long, continuous nanotubes for applications where their properties coupled with extended lengths will enable new technology developments. For example, ultralong nanotubes can be spun into fibres that are more than an order of magnitude stronger than any current structural material, allowing revolutionary advances in lightweight, high-strength applications. Long metallic nanotubes will enable new types of micro-electromechanical systems such as micro-electric motors, and can also act as a nanoconducting cable for wiring micro-electronic devices. Here we report the synthesis of 4-cm-long individual single-wall carbon nanotubes (SWNTs) at a high growth rate of 11 microm s(-1) by catalytic chemical vapour deposition. Our results suggest the possibility of growing SWNTs continuously without any apparent length limitation.

Microscopy, Atomic Force↗
PubMed2004

Common variants in the 5' region of the leptin gene are associated with body mass index in men from the National Heart, Lung, and Blood Institute Family Heart Study.

Linkage of body mass index (BMI) to a broad region of chromosome 7q22-35 has been reported in multiple studies. We previously published a multipoint LOD score of 4.9 at D7S1804 for BMI from the National Heart, Lung, and Blood Institute Family Heart Study. Leptin (LEP), the human homolog of the mouse obesity (ob) gene, is positioned near the linkage peak and is the most prominent candidate gene in this region. Interest in LEP as a susceptibility gene for human obesity has led to numerous linkage and association studies, but the results of these studies are still controversial. In the present study, we employed family-based tests of association with both a quantitative measure of BMI adjusted for age and sex and a dichotomously defined obesity trait. We genotyped 29 single-nucleotide polymorphisms (SNPs) spanning 240 kb around the LEP gene in the 82 extended pedigrees with the strongest evidence for linkage. When the programs TRANSMIT and FBAT were used, a number of SNPs showed association in men but not women, for both the quantitative and qualitative trait definitions (P<.05). Five SNPs (H1328084, H1328083, H1328082, H1328081, and H1328080) positioned 2 kb beyond the previously defined promoter region showed strong association in single-marker and multiple-marker haplotype analysis. This five-marker haplotype (frequency 49% in this sample) is overtransmitted to obese offspring (P=.00005). All five of these SNPs are predicted to modify transcription-factor binding sites. This may indicate new functional variants in an extended promoter region of LEP.

Body Mass Index↗
PubMed2004

Mechanical strength of laser-welded cobalt-chromium alloy.

The purpose of this study was to investigate the effect of the output energy of laser welding and welding methods on the joint strength of cobalt-chromium (Co-Cr) alloy. Two types of cast Co-Cr plates were prepared, and transverse sections were made at the center of the plate. The cut surfaces were butted against one another, and the joints welded with a laser-welding machine at several levels of output energy with the use of two methods. The fracture force required to break specimens was determined by means of tensile testing. For the 0.5-mm-thick specimens, the force required to break the 0.5-mm laser-welded specimens at currents of 270 and 300 A was not statistically different (p > 0.05) from the results for the nonwelded control specimens. The force required to break the 1.0-mm specimens double-welded at a current of 270 A was the highest value among the 1.0-mm laser-welded specimens. The results suggested that laser welding under the appropriate conditions improved the joint strength of cobalt- chromium alloy.

Biocompatible Materials↗
PubMed2004

Parity-violating electron deuteron scattering and the proton's neutral weak axial vector form factor.

We report on a new measurement of the parity-violating asymmetry in quasielastic electron scattering from the deuteron at backward angles at Q2=0.038 (GeV/c)2. This quantity provides a determination of the neutral weak axial vector form factor of the nucleon, which can potentially receive large electroweak corrections. The measured asymmetry A=-3.51+/-0.57 (stat)+/-0.58 (syst) ppm is consistent with theoretical predictions. We also report on updated results of the previous experiment at Q2=0.091 (GeV/c)2, which are also consistent with theoretical predictions.

Journal Article↗