Biomedical subjects

Yunhua Wang

Publications and source records attributed to Yunhua Wang.

10 recordsLinked to original sources

PubMed2006

Supra-assembly of siliceous vesicles.

We report a new approach to produce macroporous ( approximately 110 nm in diameter) ordered siliceous foams (MOSF) by using block copolymers as templates in the absence of any organic cosolvent. The fine three-dimensional honeycomb structure of MOSF was determined by electron tomography. A formation mechanism of MOSF that spans from the atomic to macroscopic scale is proposed, which involves the cooperative self-assembly of unilamellar vesicles followed by the supra-assembly of vesicles. The fusion of soft vesicles finally leads to MOSF with well-ordered and defined honeycomb structures.

Journal Article↗

PubMed2006

High-throughput DNA methylation profiling using universal bead arrays.

We have developed a high-throughput method for analyzing the methylation status of hundreds of preselected genes simultaneously and have applied it to the discovery of methylation signatures that distinguish normal from cancer tissue samples. Through an adaptation of the GoldenGate genotyping assay implemented on a BeadArray platform, the methylation state of 1536 specific CpG sites in 371 genes (one to nine CpG sites per gene) was measured in a single reaction by multiplexed genotyping of 200 ng of bisulfite-treated genomic DNA. The assay was used to obtain a quantitative measure of the methylation level at each CpG site. After validating the assay in cell lines and normal tissues, we analyzed a panel of lung cancer biopsy samples (N = 22) and identified a panel of methylation markers that distinguished lung adenocarcinomas from normal lung tissues with high specificity. These markers were validated in a second sample set (N = 24). These results demonstrate the effectiveness of the method for reliably profiling many CpG sites in parallel for the discovery of informative methylation markers. The technology should prove useful for DNA methylation analyses in large populations, with potential application to the classification and diagnosis of a broad range of cancers and other diseases.

Base Sequence↗

PubMed2005

Deletions within a CA-repeat-rich region of intron 4 of the human SP-B gene affect mRNA splicing.

Length variants within a CA-repeat-rich region of intron 4 of the human SP-B (pulmonary surfactant protein-B) gene are associated with several lung diseases. The hypothesis that SP-B intron 4 affects mRNA splicing was studied. SP-B minigenes containing exons 1-6 with a normal-sized intron 4 (pBi4normal) or intron 4 containing deletions (pBi4del) of 193, 211, 264 or 340 bp were expressed in CHO (Chinese hamster ovary) cells by transient transfection. Two forms of SP-B transcripts, normal and incompletely spliced, were detected. With pBi4normal, normal-sized SP-B mRNA was the predominant form and a very low amount of incompletely spliced mRNA was present, whereas with the pBi4del variants the amount of normal SP-B mRNAs was lower and the amount of incompletely spliced mRNA was relatively high. Reverse transcription-PCR results and sequencing data indicated that the incompletely spliced SP-B RNA contained intron 4 sequence, and this incompletely spliced RNA was also observed in normal lung. Lung cancer tissues with intron 4 deletions exhibited a larger amount of abnormally spliced RNAs compared with normal lung tissue or cancerous tissue with normal-sized intron 4. The results indicate that intron 4 length variants affect SP-B mRNA splicing, and that this may contribute to lung disease.

Animals↗

PubMed2004

Differential allele expression of host defense genes, pulmonary surfactant protein-A and osteopontin, in rat.

Differential allele-specific expression has been observed in several genes involved in immunity. SP-A and OPN play a role in innate host defense. To determine whether SP-A and OPN are subject to differential allele-specific regulation, we investigated their gene or allele-specific expression in various tissues. The results showed: (1) Tissue-specific expression with high levels in lung (SP-A) and kidney (OPN). (2) Differences in allele-specific expression among individuals and tissues. SP-A showed an exclusively balanced biallelic expression (BB) in lung, but both BB and imbalanced biallelic (IB) expression in colon. Allele expression of OPN was more heterogeneous, e.g. in colon BB (22%), IB (64%), and monoallelic expression (MO) (14%). (3) Differential allele-specific expression was observed in all tissues studied (OPN) or in all extrapulmonary tissues (SP-A). (4) Family studies indicated that inheritable factor(s) may be involved in the regulation of allele-specific expression. (5) Analysis of co-expression of gene-specific alleles from double heterozygous rats revealed lack of coordinate allele expression among SP-A, SP-D, and OPN. We conclude that allele-specific expression occurs among genes of innate host defense. This may yet provide another level of regulatory complexity for molecules involved in the first line of defense.

Alleles↗

PubMed2004

[Segregation of sex chromosomes in the spermatozoa of 46, XY/47, XXY patients with oligozoospermia by dual fluorescence in-situ hybridization].

OBJECTIVE: To observe the segregation of sex chromosomes in the spermatozoa of a 46, XY/47, XXY patient with oligozoospermia. METHODS: The number of X and Y chromosomes of the ejaculated spermatozoa from the patient with mosaic 46, XY/47, XXY was analysed by X/Y dual fluorescence in-situ hybridization (FISH). RESULTS: Of the 100 spermatozoa analysed, 97 showed either one X chromosome-specific green signal or one Y-chromosome-specific red Y signal in each spermatozoon and only 3 showed no signal. The frequencies of X- and Y-bearing spermatozoa were 49% and 48% respectively. The ratio of X- to Y-bearing spermatozoa was about 1:1 as expected. There was no statistical difference between the chromosome XX and XY frequencies in each spermatozoon from the patient in comparison with those estimated in the control. CONCLUSION: The spermatozoa of 46, XX/47, XXY mosaic patients have a normal gonosomal complement, which allows infertility treatment to be carried out by ICSI.

Adult↗

PubMed2003

Dissociation of human and computer voices in the brain: evidence for a preattentive gestalt-like perception.

We investigated the early ("preattentive") cortical processing of voice information, using the so-called "mismatch response". This brain potential allows inferences to be made about the sensory short-term store. Most importantly, the mismatch potential also provides information about the organization of long-term memory traces in the auditory system. Such traces have reliably been reported for phonemes. However, it is unclear whether they also exist for human voice information. To explore this issue, 10 healthy subjects were presented with a single word stimulus uttered by voices of different prototypicality (natural, manipulated, synthetic) in a mismatch experiment (stimulus duration 380 msec, onset-to-onset interval 900 msec). The event-related magnetic fields were recorded by a 148-channel whole-head magnetometer and a source current density modeling of the magnetic field data was performed using a minimum-norm estimate. Each deviating voice signal in a series of standard-voice stimuli evoked a mismatch response that was localized in temporal brain regions bilaterally. Increased mismatch related magnetic flux was observed in response to decreased prototypicality of a presented voice signal, but did not correspond to the acoustic similarity of standard voice and deviant voices. We, therefore, conclude that the mismatch activation predominantly reflects the ecological validity of the voice signals. We further demonstrate that the findings cannot be explained by mere acoustic feature processing, but rather point towards a holistic mapping of the incoming voice signal onto long-term representations in the auditory memory.

Acoustic Stimulation↗

PubMed2003

Quality of EEG in simultaneous EEG-fMRI for epilepsy.

It is now possible to record the EEG continuously during fMRI studies. This is a very promising methodology that combines knowledge about neuronal activity and its metabolic response. The EEG recorded inside the fMRI scanner is, however,heavily contaminated by artifacts caused by the high intensity magnetic field and rapidly changing field gradients. Methods have been reported in the literature to reduce or eliminate these artifacts, in particular the ballistocardiogram and the artifact caused by currents induced by rapidly changing magnetic gradients. Nevertheless, recording the EEG simultaneously with fMRI remains an extremely delicate operation. In addition the use of artifact removal methods has only been reported by the laboratories in which they were developed. We report here the practical procedures we developed to reduce artifacts in a series of 10 epileptic patients, in the context of the visualization of epileptic spikes. We illustrate the effectiveness of methods designed to remove the scanning artifact and present new methods for removing the ballistocardiographic artifact. We present and evaluate techniques to obtain an EEG of good quality when performing simultaneous EEG and fMRI studies.

Artifacts↗

PubMed2003

Effect of preoperative transcatheter arterial chemoembolization on apoptosis of hepatocellular carcinoma cells.

OBJECTIVE: To evaluate the effect of preoperative transcatheter arterial chemoembolization(TACE) on apoptosis of hepatocellular carcinoma (HCC) cells. METHODS: A total of 136 patients with HCC underwent liver resection. One to five courses of TACE prior to liver resection were performed in 79 patients (TACE group), in which one to four courses of chemotherapy alone were performed in 11 patients (group A), one to five courses of chemotherapy combined with iodized oil were performed in 33 patients (group B), one to three courses of chemotherapy combined with iodized oil and gelatin sponge were performed in 23 patients group C) and one to three courses of chemotherapy combined with iodized oil, ethanol and gelatin sponge were performed in 12 patients (group D). The other 57 patients only received liver resection (non-TACE group). The extent of apoptosis was analyzed by transferase-mediated dUTP nick end labeling (TUNEL) staining. The expressions of Bcl-2 and Bax protein were detected by immunohistochemical method. RESULTS: The apoptotic index(AI) and level of Bax protein in HCC cells were significantly higher in groups A, B, C and D than those in the non-TACE group (P < 0.05). The level of Bcl-2 protein and ratio of Bcl-2 to Bax protein of HCC cells were significantly lower in Groups A, B, C and D than those in the non-TACE group (P < 0.05). CONCLUSION: Preoperative TACE regimens may enhance apoptosis of HCC cells by up-regulating the expression of Bax protein and down-regulating the expression of Bcl-2 protein and ratio of Bcl-2 to Bax protein expression.

Adult↗

PubMed2002

The BOLD response to interictal epileptiform discharges.

We studied single-event and average BOLD responses to EEG interictal epileptic discharges (IEDs) in four patients with focal epilepsy, using continuous EEG-fMRI during 80-min sessions. The detection of activated areas was performed by comparing the BOLD signal at each voxel to a model of the expected signal. Since little is known about the BOLD response to IEDs, we modeled it with the response to brief auditory events (G. H., NeuroImage 9, 416-429). For each activated area, we then obtained the time course of the BOLD signal for the complete session and computed the actual average hemodynamic response function (HRF) to IEDs. In two of four patients, we observed clear BOLD responses to single IEDs. The average response was composed of a positive lobe peaking between 6 and 7 s in all patients and a negative undershoot in three patients. There were important variations in amplitude and shape between average HRFs across patients. The average HRF presented a wider positive lobe than the Glover model in three patients and a longer undershoot in two. There was a remarkable similarity in the shape of the HRF across areas for patients presenting multiple activation sites. There was no clear correlation between the amplitude of individual BOLD responses and the amplitude of the corresponding EEG spike. The possibility of a longer HRF could be used to improve statistical detection of activation in simultaneous EEG-fMRI. The variability in average HRFs across patients could reflect in part different pathophysiological mechanisms.

Adolescent↗

PubMed2002

[Effect of fertilization on the qualities of sweet pepper in greenhouse culture].

In order to study the effect of fertilization on the qualities of sweet pepper(Capsicum annul L) cultured in greenhouse, the experiment was carried out by drop irrigation. The results showed that the most sensitive organ of sweet pepper for nitrate was lateral branch, in which the nitrate content was highest. The nitrate content in leaf was lower than that in lateral branch, and in fruit, the nitrate content was the lowest. High fertilization of N, P and K had no negative influence on content of nitrate and total soluble sugars in fruit. The content of soluble sugars in fruit were about 50%-55% under all treatment and higher than that in leaf and lateral branch. Decreasing fertilization would cause increasing of the inosital and sucrose contents. Glucose and fructose were the main soluble sugars in fruit. The metabolism of carbohydrates was weakened by high fertilization, and it expressed as restraining the accumulation of starch content in leaf. The content of starch was the highest in fruit. The lipid content were exceed 3-4 times in the leaf than in the lateral branch and fruit, and perhaps, it was due to the higher content of chlorophyll in the leaf.

Capsicum↗