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Biomedical subjects

B Xu

Publications and source records attributed to B Xu.

At least 19 recordsLinked to original sources

Quality of life outcomes following laparoscopic total mesorectal excision for low rectal cancers: a clinical control study.

AIMS: To evaluate the health-related quality of life (HRQoL) outcomes in patients undergoing laparoscopic total mesorectal excision (LTME) with anal sphincter preservation (ASP) for low rectal cancers. METHODS: Patients undergoing LTME with ASP or open procedures (OTME) for low rectal cancers were prospectively followed up. All patients were treated in curative attempt and were free of local recurrence during the study. HRQoL was assessed by questionnaires during 3-6 months, 12-18 months, and 2-5 years after surgery. RESULTS: From June 2001 to March 2006, 125 patients undergoing LTME and 103 undergoing OTME were included in this study. In contrast to OTME patients, the LTME ones showed significantly better physical function during 3-6 months after surgery, less micturition problems within 12-18 months, less male sexual problems and better sexual function during 12-18 months after surgery, with better sexual enjoyment after 24 months postoperatively. Both groups showed significant improvement in most subscales from the first to the second assessment, and an improvement in sexual enjoyment from the second to the third assessment. The sexual function, micturition problems and male sexual problems in the LTME group significantly improved from the first to the second assessment, whereas the sexual function in the OTME group improved from the second to the third assessment. CONCLUSIONS: Patients undergoing LTME for low rectal cancers can achieve superior postoperative HRQoL than patients undergoing OTME, with superior physical function, micturition function, overall sexual and male sexual functions in the short term, and better sexual enjoyment in the long term. The HRQoL of both LTME and OTME patients may be expected to improve over time, particularly over the first postoperative year.

Adult↗

Chemical composition, crystal size and lattice structural changes after incorporation of strontium into biomimetic apatite.

Recently, strontium (Sr) as ranelate compound has become increasingly popular in the treatment of osteoporosis. However, the lattice structure of bone crystal after Sr incorporation is yet to be extensively reported. In this study, we synthesized strontium-substituted hydroxyapatite (Sr-HA) with different Sr content (0.3%, 1.5% and 15% Sr-HA in mole ratio) to simulate bone crystals incorporated with Sr. The changes in chemical composition and lattice structure of apetite after synthetic incorporation of Sr were evaluated to gain insight into bone crystal changes after incorporation of Sr. X-ray diffraction (XRD) patterns revealed that 0.3% and 1.5% Sr-HA exhibited single phase spectrum, which was similar to that of HA. However, 15% Sr-HA induced the incorporation of HPO4(2-) and more CO3(2-), the crystallinity reduced dramatically. Transmission electron microscopy (TEM) images showed that the crystal length and width of 0.3% and 1.5% Sr-HA increased slightly. Meanwhile, the length and width distribution were broadened and the aspect ratio decreased from 10.68+/-4.00 to 7.28+/-2.80. The crystal size and crystallinity of 15% Sr-HA dropped rapidly, which may suggest that the fundamental crystal structure is changed. The findings from this work indicate that current clinical dosage which usually results in Sr incorporation of below 1.5% may not change chemical composition and lattice structure of bone, while it will broaden the bone crystal size distribution and strengthen the bone.

Biocompatible Materials↗

Levodopa increases memory encoding and dopamine release in the striatum in the elderly.

Normal aging is associated with a decrease in dopaminergic function and a reduced ability to form new motor memories with training. This study examined the link between both phenomena. We hypothesized that levodopa would (a) ameliorate aging-dependent deficits in motor memory formation, and (b) increase dopamine availability at the dopamine type 2-like (D2) receptor during training in task-relevant brain structures. The effects of training plus levodopa (100mg, plus 25mg carbidopa) on motor memory formation and striatal dopamine availability were measured with [(11)C]raclopride (RAC) positron emission tomography (PET). We found that levodopa did not alter RAC-binding potential at rest but it enhanced training effects on motor memory formation as well as dopamine release in the dorsal caudate nucleus. Motor memory formation during training correlated with the increase of dopamine release in the caudate nucleus. These results demonstrate that levodopa may ameliorate dopamine deficiencies in the elderly by replenishing dopaminergic presynaptic stores, actively engaged in phasic dopamine release during motor training.

Aged↗

Fermi level alignment in self-assembled molecular layers: the effect of coupling chemistry.

Photoelectron spectroscopy was used to explore changes in Fermi level alignment, within the pi-pi* gap, arising from modifications to the coupling chemistry of conjugated phenylene ethynylene oligomers to the Au surface. Self-assembled monolayers were formed employing either thiol (4,4'-ethynylphenyl-1-benzenethiol or OPE-T) or isocyanide (4,4'-ethynylphenyl-1-benzeneisocyanide or OPE-NC) coupling. The electronic density of states in the valence region of the two systems are nearly identical with the exception of a shift to higher binding energy by about 0.5 eV for OPE-NC. Corresponding shifts appear in C(1s) spectra and in the threshold near E(F). The lack of change in the optical absorption suggests that a rigid shift of the Fermi level within the pi-pi* gap is the major effect of modifying the coupling chemistry. Qualitative consideration of bonding in each case is used to suggest the influence of chemisorption-induced charge transfer as a potential explanation. Connections to other theoretical and experimental work on the effects of varying coupling chemistries are also discussed.

Journal Article↗

Interfacial behaviour of strontium-containing hydroxyapatite cement with cancellous and cortical bone.

The bone-bonding behaviors of various biomaterials have been extensively investigated. However, the precise mechanisms of bone bonding have not yet been clarified, and the differences in interfacial behaviors of biomaterial bonding with cancellous bone and cortical bone have not yet been understood. In this study, strontium-containing hydroxyapatite (Sr-HA) cement, in which 10% calcium ions were substituted by strontium, was performed in a rabbit hip replacement model. Six months later, the morphology and chemical composition of interfaces between Sr-HA cement with cancellous bone and cortical bone were evaluated by field emission scanning electron microscopy (FESEM) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Remarkable differences between these two interfaces were suggested both in morphology and chemical compositions. An apatite layer was found between Sr-HA cement and cancellous bone with a thickness of about 70 microm. However, only a very thin interface (about 1 microm) was formed with cortical bone. As for the cancellous bone/cement interface, high ions intensity of Ca, P, Sr, Na, and O were confirmed by FESEM-EDX and ToF-SIMS. Differences in morphology and chemical component between these two interfaces provided convincing evidences for the proposed dissolution-precipitation coupling mechanism in the formation of biological apatite.

Animals↗

Lipoprotein lipase gene S447X polymorphism modulates the relation between central obesity and serum lipids, a twin study.

OBJECTIVE: To investigate the impact of lipoprotein lipase (LPL) gene S447X polymorphism on the relation between central obesity and lipid levels. DESIGN: A total of 961 adult twin pairs were included from the program of Chinese Twin Registry, between 2001 and 2002. Central obesity was defined as waist circumference > or =90 cm for male and > or =80 cm for female. Two statistical methods were performed to test the modification effect of S447X polymorphism of LPL gene on the relation between central obesity and lipid levels: one was Generalized Estimating Equation (GEE) models for all twin pairs and the other was co-twin matched case-control analysis in 82 central obesity discordant monozygotic twin pairs. RESULTS: In GEE models for all twins, central obesity was significantly associated with serum lipids except for high-density lipoprotein (HDL), while X447 allele had favorable effects on the levels of triglyceride (TG), HDL and TG to HDL ratio (TG/HDL). The interactions of S447X polymorphism and central obesity were statistically significant for TG/HDL and HDL. In central obesity discordant monozygotic twin pairs, central obesity was significantly related with 26.2% increase of TG and 27.2% increase of TG/HDL in S/S447 genotype, while in 447X allele carrier, central obesity was significantly related with 13.7% increase of HDL. CONCLUSION: These results suggest that LPL gene S447X polymorphism modifies the relation between central obesity and serum lipids, which also stresses the importance of reducing waist circumference to improve serum lipids for people with central obesity, especially those with S/S447 genotype.

Adult↗

Language lateralization and the role of the fusiform gyrus in semantic processing in young children.

We used blood oxygen-dependent (BOLD) fMRI technique at 1.5 T to examine brain regions associated with language comprehension in normally developing children, age 5 to 10 years. Twenty-three children participated in the study using an auditory semantic decision task which varied in task difficulty. Analysis of individual participants' data showed patterns of activation largely consistent with previous neuroimaging findings in adult language processing. Group data analysis also showed a strong left-lateralized pattern of activation that closely resembles those typically observed in adults. In addition, significant activation in the left fusiform gyrus was observed and was associated with task accuracy. This finding suggests that auditory semantic processing in young children may recruit cortical regions associated with word reading in adults prior to the initiation of a semantic category decision, a process which is consistent with patterns of early word recognition process and language development.

Age Factors↗

DOTS in China - removing barriers or moving barriers?

In 1992, China initiated its modern National TB Control Programme (NTP) with DOTS strategy through a project funded by a World Bank loan. Key motives for the revised NTP-DOTS were to reduce financial barriers to patients by removing fee charges for diagnosis and treatment, and to address regressive suppliers' incentives for appropriate referrals. This study aims to assess to what extent China's NTP subsidies are achieving the objective of removing financial barriers to care in terms of patients' expenditure. One county with NTP-DOTS - Jianhu - and one county without - Funing - were selected. A cohort of 493 tuberculosis patients newly diagnosed in 2002 was interviewed by questionnaire. The main outcome measure was tuberculosis patients' expenditure on medical care and transportation/accommodation from the onset of symptoms to treatment completion. During the follow-up period, Funing started implementing NTP-DOTS, which offered a possibility of longitudinal comparison both between counties and within county. Ninety-four per cent (465/493) of subjects were followed-up. The mean total patient's expenditure on TB medical care and transportation/accommodation before TB diagnosis was higher in Jianhu than in Funing (715 vs. 256CNY), whereas it was higher in Funing (835 vs. 157CNY) after diagnosis. After implementing NTP-DOTS in Funing, expenditure after diagnosis decreased slightly whereas expenditure before diagnosis increased remarkably. We found that the market incentive structures in the reformed health system appear to have a stronger regressive effect and may result in prolonged delays before effective treatment can be given. We believe that doctors adapt to new incentive structures, with bonus income being linked to the hospitals' fee-for-service revenue, and find new ways of keeping revenue at the old levels, which reduce or eliminate the intended effect of the subsidies. TB patients suffer a heavy economic burden even in counties where NTP-DOTS treatment is subsidized. The total patient expenditure was reduced only marginally, but shifted substantially from after diagnosis to before diagnosis. The shift could imply delays in diagnosis and treatment with an increased risk of infection transmission.

Adolescent↗

Does the pill make a difference? Previous maternal use of contraceptive pills and allergic diseases among offspring.

BACKGROUND: Maternal use of oral contraceptive pills (OCPs) might increase the prevalence of allergic diseases among offspring. The aim of the study was to clarify if there are differences between OCP types in this association. METHODS: Primary outcomes were asthma, allergic rhinitis and atopic eczema among 1182 children (618 asthmatic and 564 controls) aged 5-6 years. RESULTS: Maternal previous use of desogestrel, gestodene or cyproterone acetate before pregnancy, each combined with ethinyloestradiol (EO), increased the risk of allergic rhinitis among offspring compared with those children whose mothers had not used OCPs (OR 1.67, 95% CI 1.07-2.59, P < 0.024), and this risk was increased mainly in those children with parental allergy (OR 1.78, 95% CI 1.11-2.86, P < 0.018), especially in boys (OR 2.12, 95% CI 1.17-3.84, P < 0.014). No associations were observed between maternal use of OCPs before pregnancy and asthma or atopic eczema among offspring. The association between the previous use of OCPs and allergic rhinitis was not mediated through maternal sex steroid levels during early pregnancy, but women who had used more androgenic types of progestin formulas had higher serum levels of progesterone during early pregnancy. CONCLUSION: Maternal previous use of desogestrel, gestodene or cyproterone acetate before pregnancy, each combined with EO, increased the risk of allergic rhinitis among offspring compared with those children whose mothers had not used OCPs and this risk was detected mainly in boys and in children with parental allergy.

Adult↗

Correlation of four vascular specific growth factors with carcinogenesis and portal vein tumor thrombus formation in human hepatocellular carcinoma.

The aim of the present study was to detect the correlation between the expression of vascular endothelial growth factor (VEGF), angiopoietin 2 (Ang2), ephrinB2 and endocrine gland-derived vascular endothelial growth factor (EG-VEGF) and carcinogenesis or portal vein tumor thrombus (PVTT) formation in human hepatocellular carcinoma (HCC). The expression of VEGF, Ang2, ephrinB2 and EG-VEGF was detected by RT-PCR in 54 cases HCC without PVTT (group A), 9 cases HCC with PVTT (group B), 10 normal liver tissues (group D) and 10 cirrhosis tissues (group C). The samples were also stained with CD34 by immunohistochemistry. Quantitation of microvessel density (MVD) and semi-quantitation of VEGF, Ang2, ephrinB2 and EG-VEGF expression were analyzed to find the relations. The MVD was 146.69 +/- 77.79, 214.07 +/- 54.41, 32.85 +/- 8.49 and 34.83 +/- 8.29 in group A-D respectively with significant difference (F = 19.77, P = 0.000). The MVD in group A was higher than that in group C P = 0.006, but lower than that in group B P < or = 0.05 or 0.01. The expression levels of VEGF165, VEGF189, Ang2 and EG-VEGF mRNA were significantly different among the groups. The expression levels of VEGF165, Ang2 and EG-VEGF mRNA in group A were all higher than those in group C, but lower than those in group B P < 0.05 or 0.01. The MVD was significantly correlated with VEGF165, VEGF189, Ang2 and EG-VEGF mRNA with Spearman's related coefficient being 0.764, 0.510, 0.640 and 0.366 in HCC (P = 0.000, 0.000 0.000 and 0.003). In conclusion VEGF, Ang2 and EG-VEGF mRNA may play a role in angiogenesis and carcinogenesis of HCC. They can promote PVTT formation in HCC by modulating angiogenesis.

Angiopoietin-2↗

Seizure focus affects regional language networks assessed by fMRI.

OBJECTIVE: To investigate the degree of language dominance in patients with left and right hemisphere seizure foci compared to normal volunteers using a fMRI reading comprehension task. METHODS: Fifty patients with complex partial epilepsy, aged 8 to 56 years and 33 normal volunteers, aged 7 to 34 had fMRI (1.5 T) and neuropsychological testing. Participants silently named an object described by a sentence compared to a visual control. Data were analyzed with region of interest (ROI) analysis based on t maps for inferior frontal gyrus (IFG), midfrontal gyrus (MFG), and Wernicke area (WA). Regional asymmetry indices (AIs) were calculated [(L - R)/(L + R)]; AI > 0.20 was deemed left dominant and AI < 0.20 as atypical language. RESULTS: Left hemisphere focus patients had a higher likelihood of atypical language than right hemisphere focus patients (21% vs 0%, chi2 < 0.002). Left hemisphere focus patients, excluding those with atypical language, had lower regional AI in IFG, MFG, and WA than controls. Right hemisphere focus patients were all left language dominant and had a lower AI than controls in WA and MFG, but not for IFG. AI in MFG and WA were similar between left hemisphere focus/left language patients and right hemisphere focus patients. Patients activated more voxels than healthy volunteers. Lower AIs were attributable to greater activation in right homologous regions. Less activation in the right-side WA correlated with better verbal memory performance in right focus/left hemisphere-dominant patients, whereas less strongly lateralized activation in IFG correlated better with Verbal IQ in left focus/left hemisphere-dominant patients. CONCLUSIONS: Patients had lower asymmetry indices than healthy controls, reflecting increased recruitment of homologous right hemisphere areas for language processing. Greater right hemisphere activation may reflect greater cognitive effort in patient populations, the effect of epilepsy, or its treatment. Regional activation patterns reflect adaptive efforts at recruiting more widespread language processing networks that are differentially affected based on hemisphere of seizure focus.

Adaptation, Physiological↗

Quantum-dot growth simulation on periodic stress of substrate.

InAs quantum dots (QDs) are grown on the cleaved edge of an In(x)Ga(1-x)AsGaAs supperlattice experimentally and a good linear alignment of these QDs on the surface of an In(x)Ga(1-x)As layer has been realized. The modulation effects of periodic strain on the substrate are investigated theoretically using a kinetic Monte Carlo method. Our results show that a good alignment of QDs can be achieved when the strain energy reaches 2% of the atomic binding energy. The simulation results are in excellent qualitative agreement with our experiments.

Journal Article↗

Placental deficiency of interleukin-10 (IL-10) in preeclampsia and its relationship to an IL10 promoter polymorphism.

The placenta is pivotal in the acceptance of the feto-placental unit by the maternal immune system. Imbalance at the maternal-fetal interface of tissue pro- and anti-inflammatory cytokines may be partly involved in disease causation. Previous work has shown conflicting levels of IL-10. IL-10 levels have been shown to increase, decrease, or remain unchanged in women with preeclampsia. This study examines the difference in serum and placental IL-10 expression in women with preeclampsia and investigates if the IL10 (-1082) A promoter polymorphism contributes to lower concentrations. In a prospective case-control study of 12 women with preeclampsia and 31 controls we assessed serum IL-10 by ELISA, placental mRNA by quantitative PCR and protein by immunohistochemistry as well as placental IL10 promoter genotype. Comparisons were made with non-parametric tests where necessary and chi-square. We found a significant reduction in placental IL-10 mRNA and protein expression in women with preeclampsia compared to controls. Women with the AA IL-10 promoter genotype expressed less placental IL-10 mRNA compared to women with AG or GG genotype. There was no difference in serum IL-10 concentrations between different genotypes. Preeclampsia is associated with a deficiency of placental IL-10. Placental AA genotype in the promoter region results in significantly less placental IL-10.

Adult↗

Garlic increases IL-10 and inhibits TNFalpha and IL-6 production in endotoxin-stimulated human placental explants.

Preeclampsia is a multisystem disorder manifest by hypertension after 20 weeks' gestation associated with end organ damage, usually proteinuria. The placenta is thought to be pivotal in the pathogenesis of the disease. Both the placenta and the maternal systemic response are characterised by heightened inflammation. Garlic has been shown to have anti-inflammatory and pro-apoptotic properties amongst others. It was hypothesised that treating placental explants with garlic may inhibit the production of inflammatory cytokines (interleukin-6 (IL-6) and tumour necrosis factor (TNFalpha)) and stimulate the production of anti-inflammatory cytokines (interleukin-10 (IL-10)) by the placental explants. Garlic, we hypothesised, would also stimulate apoptosis in the explants as measured by soluble TNF-related apoptosis-inducing ligand/Apo-2L (sTRAIL) production. Normal placental explants (n=5) and explants from women who had preeclampsia (n=4) were cultured in the presence of various garlic concentrations (10-1000 microg/mL). The lowest garlic concentration (10 microg/mL) increased the normal explant production of IL-10 by 29.2% (12.2, 57.5%; p<0.01) while inhibiting the production of IL-6 by 23.5% (8.9, 32.5%; p<0.01) (normal explants) and TNFalpha by 19.4% (4.5, 35.3%; p<0.05) (preeclamptic explants). Garlic resulted in an increase in IL-10 production at lower doses (normal explants only) and inhibition of the production of IL-10 at higher doses (normal and preeclamptic explants). Garlic also resulted in a dose-dependent reduction of IL-6 and TNFalpha. Initially there was no change in sTRAIL production; however, at the highest garlic concentrations there was a significant increase in production. We thus conclude that garlic may have an immunomodulatory effect on normal and preeclamptic placentas.

Adult↗

Real time PCR on disposable PDMS chip with a miniaturized thermal cycler.

This paper presents the design and implementation of a low-cost miniature PCR device consisting of a disposable reactor chip and a miniature thermal cycler. The simple fabrication of the PCR chip by PDMS (Polydimethylsiloxane) does not need micro-machining or photolithography processes. The thermal cycler was built with a thin film heater for heating and a fan for rapid cooling. This device can perform PCR tests in a single well chip or a multiple-well chip. It can run PCR reactions of different volumes to meet specific application requirements. The smallest reaction volume tested in this work is 0.9 microL. In addition, this device fits any standard fluorescence microscope for real time detection, which makes real time PCR affordable for most research labs and clinics with a fluorescence microscope. Real-time PCR of E. coli stx1 has been demonstrated with the device described.

Computer Systems↗

Cytokine expression during acute graft-versus-host disease after allogeneic peripheral stem cell transplantation.

Acute graft-versus-host disease (aGVHD) is one of the major problems following allogeneic peripheral blood stem cell transplantation (allo-PBSCT). In order to investigate the pathogenesis of human aGVHD, we analyzed cytokine gene expression and cytokine secretion by peripheral blood mononuclear cells (PBMC) in 30 patients who underwent allo-PBSCT. In this study, reverse transcription-polymerase chain reaction (RT-PCR) was used to explore the mRNA expression of interleukin (IL)-2, interferon (IFN)-gamma, IL-4, IL-10 and IL-12 in the PBMC of allo-PBSCT patients with aGVHD and in controls. The concentrations of these cytokines and of IL-18 were also measured by means of ELISA in medium obtained from cultured leukocytes after stimulation with PHA or LPS. Compared with the normal allo-PBSCT group (n=14), IL-2 and IFN-gamma were detected more frequently in aGVHD group (n=16). IL-12 and IL-18 were elevated, while IL-10 level decreased in the same group. There is no difference in IL-4 gene expression between patients with or without aGVHD, but the concentration of IL-4 for patients with grade II-IV aGVHD decreased. These data suggest that IL-2, IFN-gamma, IL-12 and IL-18 play important roles in the development of aGVHD in humans.

Acute Disease↗

Clinical study of recombinant adenovirus-p53 (Adp53) combined with hyperthermia in advanced cancer (a report of 15 cases).

The study was to evaluate the efficacy of the Adp53 combined with hyperthermia on advanced cancer. Fifteen patients with advanced cancer were enrolled in this clinical trial. Thirteen patients with recurrent tumours failed in conventional treatments and the two other patients with primary tumour received no treatment before they were enrolled. Recombinant adenovirus-p53 (Adp53) is a E1 substituted replication-incompetent recombinant adenovirus encoding the human wild-type p53 (wtp53) gene. The 15 patients were intra-tumourally injected with Adp53, 1x10(12)vp (virus particle) once a week, with a total of 4-8 times was given. The temperature being set hyperthermia every week 3 days after the injection of Adp53 at 43-44 degrees C using 915 MHz microwave machine for superficial tumour for 1 h or at 42-43 degrees C using 41 MHz radiofrequency machine for deep-seated tumour for 1 h. Among the 15 patients, five concurrently were added with radiotherapy and three were added with cisplatin-based chemotherapy. The treatment achieved CR in two cases, PR in four cases, SD in eight cases and PD in one case and, after the treatment, tumours of two cases disappeared and seven of the other 13 cases (54%) had low-density area (LDA) of more than 50% on CT images in tumours. In the 15 patients, no dose-limiting toxicity and adverse events were noted, except transient fever after Adp53 administration. In conclusion, Adp53 combined with hyperthermia was safe and effective in patients with advanced cancer and p53 gene therapy was potential to thermosensitize in advanced cancer.

Adenoviruses, Human↗

Applications of topologically segregated bilayer beads in 'one-bead one-compound' combinatorial libraries.

We recently reported the use of a biphasic approach to generate topologically segregated bilayer beads. In generating 'one-bead one-compound' (OBOC) combinatorial libraries, novel encoding methods have been applied to these beads such as the testing library compound and the coding tags residing on the outer layer and inner core of each bead, respectively. In this report, we further exploit these bilayer beads by preparing target bead-libraries with low concentration of random peptides on the outer layer, and full substitution of coding peptides in the bead interior. The low concentration of peptide on the bead surface enables us to greatly increase the stringency of screening so that higher affinity ligands can easily be identified. Full substitution of the inner core of the beads enables us to have enough coding peptides inside the bead for direct microsequencing with Edman chemistry. The biphasic approach of preparing bilayer beads can be carried out at any point during the library construction. Therefore, the nonsequencable or fixed structures of the peptides can be bypassed in the coding tags. As a result, peptide libraries that otherwise cannot be sequenced can now be sequenced, and peptide segments with fixed residues within the libraries can be bypassed so that the microsequencing time can be significantly shortened. Furthermore, peptides with a branch of random sequence in the middle of a fixed peptide chain can be encoded with just the random sequence in the bead interior. We have successfully applied these novel OBOC library concepts in the optimization of cell-surface ligands for a human T-cell leukemia, Jurkat, cell line.

Alkaline Phosphatase↗