Biomedical subjects

J Huang

Publications and source records attributed to J Huang.

At least 37 records · Page 2Linked to original sources

PubMed2006

Visual cortical inhibitory function in migraine is not generally impaired: evidence from a combined psychophysical test with an fMRI study.

A robust, visual masking test that was developed to be feasible with functional magnetic resonance imaging (fMRI) was used to examine the visual cortical inhibitory function in migraine patients with visual aura at both psychophysical and cortical levels. The study showed that the decreased visibility of a visual target was associated with a reduction in cortical activation in the primary visual cortex. The suppression of the transient on-response and after-discharge of neurons to the target was most likely to be responsible for reducing cortical activation, rendering the target less visible or invisible. The migraine patients were equally susceptible to visual masking and showed no difference in cortical activation when compared with age- and sex-matched non-headache controls, demonstrating that visual cortical inhibitory function was not impaired under the experimental conditions. Although these results are not in conflict with the general cortical hyperexcitability theory in migraine, they provide evidence to show the limitation to the theory.

Adult↗

PubMed2006

Detecting linkage disequilibrium in the presence of locus heterogeneity.

Locus heterogeneity is a common phenomenon in complex diseases and is one of the most important factors that affect the power of either linkage or linkage disequilibrium (LD) analysis. In linkage analysis, the heterogeneity LOD score (HLOD) rather than LOD itself is often used. However, the existing methods for detecting linkage disequilibrium, such as the TDT and many of its variants, do not take into account locus heterogeneity. We propose two novel likelihood-based methods, an LD-Het likelihood and an LD-multinomial likelihood, to test linkage disequilibrium (LD) that explicitly incorporate locus heterogeneity in the analysis. The LD-Het is applicable to general nuclear family data but requires a working penetrance model. The LD-multinomial is only applicable to affected sib-pair data but does not require specification of a trait model. For affected sib-pair data, both methods have similar power to detect LD under the recessive model, but the LD-multinomial model has greater power when the underlying model is dominant or additive.

Chromosome Mapping↗

PubMed2006

A family-based association study of megsin A23167G polymorphism with susceptibility and progression of IgA nephropathy in a Chinese population.

AIMS: To investigate the association of megsin A23167G polymorphism with susceptibility and progression of IgA nephropathy in Chinese population. METHODS: 435 IgA nephropathy patients and their family members were recruited for a family-based association study. Genotypes of megsin A23167G were determined by direct sequencing. The results were analyzed by transmission disequilibrium test (TDT) and haplotype relative risk (HRR). Clinical data and histological scores of renal lesions were compared between patients with different genotypes. According to disease stability, IgA nephropathy patients were divided into progressive group and stable group. The distribution of genotype frequencies were compared between the 2 groups. RESULTS: TDT revealed that megsin 23167G alleles were transmitted more frequently from heterozygous parents to patients than expected (classical TDT: chi2 = 5.435, p = 0.020, extended TDT: chi2 = 5.017, p = 0.025). HRR analyses showed significant differences between transmitted and nontransmitted allele frequencies (chi2 = 7.006, p = 0.008, HRR = 1.762). The scores of glomerular index and glomerular sclerosis index were higher in GG genotype patients than those in other genotypes (F = 4.570, p = 0.033, F = 4.324, p = 0.038, respectively). The distribution frequency of GG genotype in the progressive group was higher than that of the stable group (chi2 = 4.370, p = 0.037). No statistical difference was found in tubulo-interstitial index, vascular index and clinical characteristics between the 2 groups. CONCLUSION: The polymorphism of megsin A23167G is associated with susceptibility and progression of IgA nephropathy in Chinese population. GG genotype is associated with severe histological lesions and progression of the disease.

Adult↗

PubMed2006

SLC11A1 (formerly NRAMP1) gene polymorphisms and tuberculosis susceptibility: a meta-analysis.

OBJECTIVE: Although many case-control studies have investigated the association between the SLC11 A1 gene polymorphisms and tuberculosis (TB) susceptibility, results were conflicting due to limited power. We reviewed the literature systematically by means of meta-analysis, provided a quantitative summary estimate on the association with TB, and examined some sources of between-study heterogeneity. DESIGN: We searched databases (MEDLINE, PUBMED and OVID) from January 1995 to December 2004 using 'gene' or 'SLC11A1' or 'NRAMP1', in combination with 'tuberculosis', performed a manual search of citations from relevant original studies and review articles, or corresponded with authors. RESULTS: The summary ORs for studies with 3'UTR, D543N, INT4 and 5'(GT)n loci allele variants in the SLC11A1 gene were 1.33 (95%CI 1.08-1.63), 1.67 (95%CI 1.36-2.05), 1.14 (95%CI 0.96-1.35) and 1.32 (95%CI 1.03-1.68), respectively, compared with their corresponding common alleles. The pooled ORs by sub-group analyses for the four loci described above were 1.20 (95%CI 0.86-1.68), 1.69 (95%CI 1.14-2.50), 1.50 (95%CI 1.17-1.91), and 1.31 (95%CI 1.05-1.64) in subjects of African descent, 1.46 (95%CI 1.10-1.94), 1.65 (95%CI 1.29-2.12), 0.91 (95%CI 0.66-1.25) and 1.86 (95%CI 1.33-2.62) in Asian subjects, 1.81 (95%CI 0.66-4.93), 1.79 (95%CI 0.72-4.47), 0.87 (95%CI 0.61-1.22) and 1.02 (95%CI 0.35-2.99) in European subjects. CONCLUSIONS: Polymorphisms at the four loci had no statistically significant association between the SLC11A1 variants and susceptibility to TB in subjects of European descent, while they showed a statistically significant association in Asian subjects (except the INT4 variant), African subjects (except the 3'UTR variant) and the population as a whole (except the INT4 variant).

Asian People↗

PubMed2005

Renal transplantation in a 14-year-old girl with vitamin B12-responsive cblA-type methylmalonic acidaemia.

Renal tubular dysfunction and chronic renal failure are well recognised complications of methylmalonic acidaemia (MMA) and can occur even in the context of optimal medical metabolic management. Organ transplantation, such as renal and combined liver and renal transplants, have been utilised in the past for children whose disease cannot be managed by conservative medical practices and those with end stage renal disease. Our patient was diagnosed with B(12)-responsive MMA (subsequently proven to be cblA-type MMA) in the postoperative period following renal transplantation for idiopathic chronic renal failure. She remains well, with excellent graft function and metabolic control 4 years after transplantation. This patient highlights the importance of testing for the inborn errors of metabolism in patients presenting with recurrent acidosis and progressive renal impairment.

Adolescent↗

PubMed2005

Glycoprotein G deletion mutants of equine herpesvirus 1 (EHV1; equine abortion virus) and EHV4 (equine rhinopneumonitis virus).

Glycoprotein G (gG) deletion mutants of EHV1 and EHV4, designated EHV1DeltagG and EHV4DeltagG, were constructed. The growth characteristics of the EHV1DeltagG mutants were similar to the parent virus. All of the EHV4DeltagG mutants grew more slowly in cell culture and produced plaques of different morphology including smaller size. The yields of both gG deletion mutant viruses in cell culture were similar to the parent viruses. Sequencing of the genes flanking gG, Southern blot, PCR and western blot analyses of the mutant viruses demonstrated that the deletions were as expected, except for EHV4DeltagG mutants, which in addition to deletion of gG contained unexpected deletions in the adjacent down stream gene ORF 71 (glycoprotein 2). Antisera to EHV1DeltagG and EHV4DeltagG neutralised the respective mutant and the parent viruses to the same titre and these antisera could be distinguished from antisera to the wild type viruses in a gG antibody detection ELISA. The mutant viruses may be useful as vaccine candidates and the deletion of gG may act as a marker to distinguish vaccinated from the naturally infected horses.

Animals↗

PubMed2005

Novel deposition of nano-sized silicon substituted hydroxyapatite by electrostatic spraying.

Suspensions containing nano-sized silicon substituted hydroxyaptite (nSiHA) particles were produced and processed for electrostatic spray deposition. No secondary phases were detected by X-ray diffraction, which indicated that the nSiHA was phase pure. Electrostatic spraying of nSiHA in cone-jet mode was achieved at flow rate of 10(-9) m3s(-1) with an applied voltage between the needle and the ring-shaped ground electrode set at 6 to 8 kV. Micrometer- and submicrometer-scaled islands of nSiHA have been deposited on glass and titanium substrates. The surface roughness of such nHA and nSiHA islands was in the range 60 to 80 nm, as measured from atomic force microscopy in tapping mode. The growth of primary human osteoblast (HOB) cells on the nSiHA deposited substrates increased with time during the 4 days of culture, and the increase was related with the Si content in substituted HA, indicating that nSiHA was able to promote and support the growth of HOB cells. Scanning electron microscopy (SEM) revealed that extracellular matrix (ECM) produced by the HOB cells on these nSiHA deposits was well organized. In addition, the presence of Ca and P containing nodules in the ECM were also confirmed by Energy Dispersive X-ray (EDX) analysis, indicating early signs of calcification fronts. The results showed that nSiHA produced by electrostatic spray deposition was able to promote the attachment and the growth of HOB cells. Therefore, electrostatic spray deposition offers great potential for the creation of bioactive surfaces to provide improved interfacial bonding with host tissues.

Cell Adhesion↗

PubMed2005

A new way of incorporating silicon in hydroxyapatite (Si-HA) as thin films.

Bioactive silicon-containing hydroxyapatite (Si-HA) thin films that can be used as coatings for bone tissue replacement have been developed. A magnetron co-sputtering technique was used to deposit Si-HA films up to 700 nm thick on titanium substrates, with a silicon level up to 1.2 wt%. X-ray diffraction demonstrated that annealing transformed the as-deposited Si-HA films which were amorphous, into a crystalline HA structure. A human osteoblast-like (HOB) cell model was used to determine the biocompatibility of these films. HOB cells were seen to attach and grow well on the Si-HA films, and the metabolic activity of HOB cells on these films was observed to increase with culture time. Furthermore, mineralisation of the cell layers was observed after 8 weeks of culture. Based on the present findings, Si-HA of different film compositions demonstrate bioactive properties in-vitro, and indicate the potential as biocoatings for a wide variety of medical implants including load-bearing applications such as the femoral stem of hip replacement implants.

Bone Substitutes↗

PubMed2005

Magnetron co-sputtered silicon-containing hydroxyapatite thin films--an in vitro study.

The use of silicon-substituted hydroxyapatite (Si-HA) as a biomaterial has been reported recently. In vivo testing has shown that Si-HA promotes early bonding of the bone/implant interface. In order to extend its usage to major load-bearing applications such as artificial hip replacement implants, it has been proposed that the material could be used in the form of a coating on implant surfaces. This paper reports a preliminary study of the biocompatibility of magnetron co-sputtered silicon-containing hydroxyapatite (Si-HA) coatings on a metallic substrate. Magnetron co-sputtered Si-HA films of thickness 600 nm with a Si content of approximately 0.8 wt% were produced on titanium substrates. X-ray diffraction analysis showed that the as-deposited Si-HA films were either amorphous or made up of very small crystals. The crystallinity of Si-HA films was increased after post-deposition heat treatment at 700 degrees C for 3 h, and the principal peaks were attributable to HA. The formation of nano-scale silicon-calcium phosphate precipitates was noted on the heat-treated films. In vitro cell culture has demonstrated that human osteoblast-like cells attached and grew well on all films, with the highest cell growth and signs of mineralisation observed on the heat-treated Si-HA films. In addition, many focal contacts were produced on the films and the cells had well-defined actin cytoskeletal organisation. This work shows that as-deposited and heat-treated Si-HA films have excellent bioactivity and are good candidates when rapid bone apposition is required. Furthermore, heat-treated Si-HA films have improved biostability compared to as-deposited films under physiological conditions.

Actins↗

PubMed2005

Regulation of TNF-related apoptosis-inducing ligand-mediated death-signal pathway in human beta cells by Fas-associated death domain and nuclear factor kappaB.

Transfectants of human CM and NES2Y beta cell lines and primary islets transfected by FADD-DN (dominant-negative form of Fas-associated death domain), a mutant of FADD and/or a superrepressor of nuclear factor kappaB (NF-kappaB) (AdIkappaB(SA)2), were examined for their susceptibility to the TRAIL (TNF-related apoptosis-inducing ligand)-induced death signal pathway, compared with controls, wild-type cells, and vector transfectants in caspase fluorescence, Western blot, electrophoretic mobility shift, apoptosis, and cytotoxicity assays. FADD-DN inhibited caspase-8 activation induced by TRAIL in the transfectants of CM and NES2Y cells. TRAIL-induced apoptosis and cytotoxicity to the FADD-DN transfectants were decreased in comparison to those responses in controls (CM, p < 0.01 and p < 0.01; NES2Y, p < 0.05, and p < 0.02, respectively). When CM, NES2Y, and primary islet cells were transfected by AdIkappaB(SA)2, TRAIL-induced IkappaB degradation and nuclear translocation of NF-kappaB p50/p65 were blocked. TRAIL-induced apoptosis and cytotoxicity to AdIkappaB(SA)2 transfectants of these cells were also reduced (CM, p < 0.02 and p < 0.02; NES2Y, p < 0.01 and p < 0.01, respectively, and islet p < 0.01 for cytotoxicity). Finally, cytotoxicity induced by TRAIL in CM and NES2Y cells transfected with both FADD-DN and AdIkappaB(SA)2 was reduced, compared with that observed in these cells transfected with either FADD-DN alone or AdIkappaB(SA)2 alone, suggesting that FADD and NF-kappaB have synergistic proapoptotic regulatory effects on the susceptibility of beta cell lines and islet cells to TRAIL-induced destruction.

Adaptor Proteins, Signal Transducing↗

PubMed2005

Angiotensin II AT-1A receptor immunolabeling in rat medial nucleus tractus solitarius neurons: subcellular targeting and relationships with catecholamines.

The angiotensin II AT-1A receptor (AT-1A) is the major mediator of the hypertensive actions of angiotensin II (ANG II) in the medial nucleus of the solitary tract (mNTS). The localization of the AT-1A receptor at surface or intracellular sites is an important determinant of its signaling properties, including intercellular or intracrine communication. However, the spatial localization of this protein, particularly within small distal or intermediate size dendrites of mNTS neurons, is unknown. Within the mNTS, ANG II and catecholamines interact in the regulation of autonomic function; however, it is unknown if AT-1A receptors are present at functional sites in catecholamine containing dendrites, or are contacted by catecholamine containing axon terminals. We compared surface and intracellular distributions of the AT-1A receptor in dendritic processes from the mNTS using immunogold electron microscopy in conjunction with immunoperoxidase labeling for tyrosine hydroxylase (TH) and morphometric analysis. Collapsed across all AT-1A-labeled dendritic profiles, immunogold labeling was more frequent in intracellular sites as compared with the plasma membrane. Small (<0.6 microm) dendritic profiles contained a higher ratio of particles associated with the surface membrane when compared with larger profiles. Approximately 27% of all AT-1A receptor-labeled dendritic profiles also contained labeling for TH. Approximately 12% of dendritic profiles single labeled for the AT-1A receptor were contacted by TH containing axons or axon terminals. The present results provide the first quantitative demonstration of select plasmalemmal and intracellular localizations of AT-1A receptors in dendritic processes of mNTS neurons, including those containing TH, or contacted by catecholaminergic axon terminals. These results suggest that AT-1A receptors are positioned for modulation of catecholamine signaling in the mNTS.

Animals↗

PubMed2005

Gender-specific association between pulse pressure and C-reactive protein in a Chinese population.

There is growing evidence that low-grade chronic inflammation, as reflected by the raised serum concentration of C-reactive protein, might be a risk factor for hypertension, in particular in women. We therefore investigated gender-specific associations of systolic and diastolic blood pressure and pulse pressure with serum C-reactive protein concentration in a Chinese population sample. In 463 participants, we measured serum C-reactive protein concentration using a high-sensitivity immunonephelometric latex-enhanced assay. We performed single and multiple linear regression analyses. The 224 male and 239 female subjects were of similar age (51.0 years) and had similar levels of systolic blood pressure (124.7 mmHg) and pulse pressure (47.1 mmHg), but men, compared with women, had higher diastolic blood pressure (79.6 vs 75.8 mmHg; P<0.0001) and body mass index (24.3 vs 23.4 kg/m2; P=0.003). Both before and after adjustment for age, age2, body mass index, current smoking, alcohol intake, and use of antihypertensive drugs, pulse pressure was significantly associated with serum C-reactive protein concentration in women (P< or =0.002) but not in men (P>0.10; P=0.02 for interaction between gender and serum C-reactive protein). In women, with one-fold increase in serum C-reactive protein concentration, pulse pressure was 1.94 mmHg higher. The categorical analyses confirmed our findings. With similar adjustments applied, women in the fourth quartile, compared with those in the lowest quartile, had a 7.6 mmHg higher pulse pressure (95% confidence interval 3.5-11.7 mmHg; P=0.0003). Furthermore, when women were analysed according to menopausal status, the association between pulse pressure and C-reactive protein was only significant in postmenopausal (P< or =0.04), but not in premenopausal, subjects (P> or =0.21). In conclusion, taken together with the previous gender-specific observations on carotid lesions and hypertension, our finding suggests that chronic low-grade inflammation might play a role in the widening of pulse pressure in Chinese women. This cross-sectional observation warrants further investigation in prospective studies.

Biomarkers↗

PubMed2005

beta2-Adrenergic receptor gene variations associated with stage-2 hypertension in northern Han Chinese.

The aim of this study was to investigate the association between polymorphisms in the beta(2)-adrenergic receptor gene (ADRB2) (-47C/T, Arg16/Gly, Gln27/Glu) and stage-2 hypertension in northern Han Chinese. We recruited 503 individuals with stage-2 hypertension and 504 age-, gender-, and area-matched controls from the International Collaborative Study of Cardiovascular Disease in Asia. Genotyping was performed using PCR-RFLP. Logistic regression analyses revealed that carriers of the Gly16 allele had a significantly higher odds ratio (OR) for hypertension, while carriers of the Glu27 allele had a significantly lower OR. In multivariate linear regression analyses, the Arg16/Gly and Gln27/Glu genotypes were significantly associated with systolic blood pressure level (p = 0.004 and p < 0.001, respectively). In haplotype analyses, we found the frequency of haplotypes composed of the Gly16 and Gln27 alleles was significantly higher, whereas the frequency of haplotypes composed of the Arg16 and Glu27 alleles was significantly lower, in hypertensives compared to their controls (both p = 0.001). These results indicate that the Gly16 and Gln27 alleles of the ADRB2 gene confer an increased risk for stage-2 hypertension in this northern Han Chinese population.

Adult↗

PubMed2005

Linkage analysis of chromosome 1 with essential hypertension and blood pressure quantitative traits in Chinese families.

Summary Several recent studies have linked human chromosome 1p to essential hypertension (EH) or blood pressure (BP) levels. In an independent population of 148 hypertensive families from China we tested these findings. Thirty highly informative microsatellite markers spanning about 284 cM were genotyped. Qualitative linkage analysis was conducted using non-parametric linkage analysis implemented within the GENEHUNTER 2.0 software, whereas quantitative analysis was performed with the variance-component method integrated in the S.O.L.A.R. 1.7.4. software with an additional Haseman-Elston method using the SAGE/SIBPAL2 program. We observed suggestive linkage between D1S2890 (1p31, 80.9 cM) and hypertension using the multipoint non-parametric linkage analysis (NPL = 2.19, P = 0.01). In the quantitative analysis we didn't observe a significant excess of identity-by-descent allele sharing between the systolic blood pressure levels and the markers. However, the D1S207 microsatellite marker (1p21) which is located about 107 cM from the telomere of 1p showed weak linkage evidence with the diastolic blood pressure levels (LOD = 1.42). These findings suggest linkage of 1p31 with essential hypertension in the ethnic Chinese, and provide a potential clue for future studies involving candidate genes for hypertension.

Adult↗

PubMed2005

A preliminary analysis of the process of protein secretion and the diversity of putative secreted hydrolases encoded in Aspergillus fumigatus: insights from the genome.

The genome sequence of Aspergillus fumigatus has enabled the annotation of genes likely to encode secreted enzymes that may be important in underpinning the natural lifestyle of the fungus and its pathogenicity. We summarize the data from the genome sequence relevant to both the process of protein secretion and the predicted hydrolase enzymes secreted by A. fumigatus.

Animals↗

PubMed2005

The ergosterol biosynthesis pathway, transporter genes, and azole resistance in Aspergillus fumigatus.

The continuous use of triazoles can result in the development of drug resistance. Azole-resistant clinical isolates, spontaneous and induced mutants of Aspergillus fumigatus have been documented. The azoles block the ergosterol biosynthesis pathway by inhibiting the enzyme 14-alpha-demethylase, product of the CYP51. Fungal azole resistance involves both amino acid changes in the target site that alter drug-target interactions and those that decrease net azole accumulation. The reduced intracellular accumulation has also been correlated with overexpression of multidrug resistance (MDR) efflux transporter genes of the ATP-binding cassette (ABC) and the major facilitator superfamily (MFS) classes. About 20 genes are involved in the A. fumigatus ergosterol biosynthesis pathway. There are several duplicated genes in this pathway. Interestingly, erg3 and erg11 showed two copies in A. fumigatus. In general, Aspergillus spp. have proportionally more MFS transporter encoding genes than Saccharomyces cerevisiae, S. pombe, and Neurospora crassa. The drug H+ (12 and 14 spanners) sub-families are also proportionally greater than in the other species. Although the numbers of ABC transporter encoding genes are comparable, again the Aspergillus spp. have more ABC transporters related to multidrug permease than the other fungal species.

ATP-Binding Cassette Transporters↗

PubMed2005

Effects of trans-resveratrol from Polygonum cuspidatum on bone loss using the ovariectomized rat model.

trans-Resveratrol (resveratrol) has been shown in several studies to significantly modulate biomarkers of bone metabolism. But, there is no direct evidence supporting its inhibitory effect towards bone loss. In the present study, effects of resveratrol on bone mineral density (BMD) and bone calcium content (BCC) were examined in the ovariectomized (OVX) rat model. Female Wistar rats were divided into four groups: SHAM group (sham-operated), OVX group (OVX control), OVX + ALD group (OVX and treated with 1.0 mg/kg of body weight of alendronate sodium), and OVX + RES group (OVX and treated with 0.7 mg/kg of body weight of resveratrol). Tested materials were given by gavage for 12 weeks after ovariectomy. Results showed that rats in the OVX, OVX + ALD, and OVX + RES groups had significantly higher body weights and feed efficiency than those in the SHAM group (P < .01). The OVX group had significantly lower femoral epiphysis BMD than the SHAM group, and epiphysis BMD in the OVX + ALD and OVX + RES groups was significantly greater than that in the OVX group (P < .05). However, the femoral midpoint BMD was not significantly different among the four groups. Additionally, animals in the OVX group had significantly lower BCC compared with the SHAM group, while the BCC of the OVX + ALD and OVX + RES groups was significantly higher than that of the OVX group (P < .05). These results indicated that resveratrol could increase epiphysis BMD and inhibit the decrease of femur BCC in OVX rats, suggesting that it could play a role in protecting against bone loss induced by estrogen deficiency.

Absorptiometry, Photon↗

PubMed2005

Radiation-induced changes in gene expression in the silkworm revealed by serial analysis of gene expression (SAGE).

Serial analysis of gene expression (SAGE) was used to examine the profile of expressed genes during embryonic development in the domesticated silkworm, Bombyx mori, after irradiation with Cobalt-60. A comparison of the SAGE sequence tags derived from irradiated embryos with those from normal embryos revealed 673 differentially expressed genes (P < 0.01 and at least three folds change). Of these, 292 genes were highly expressed in normal embryos and 381 genes were highly expressed in irradiated embryos. These results provide valuable information for understanding the mechanisms of radiation-induced changes in gene expression. In addition, it was noted that the generation of longer cDNA fragments from SAGE tags is an efficient way to identify genes, thereby facilitating the analysis of large numbers of unknown genes.

Animals↗