PubMed Health⌕ Search

Biomedical subjects

X P Zhao

Publications and source records attributed to X P Zhao.

11 recordsLinked to original sources
PubMed2006

Electrophoretic ink using urea-formaldehyde microspheres.

A kind of electronic ink, which is supported on indium-tin-oxide (ITO) glass before polymerization, is prepared using urea and formaldehyde resin as wall materials, in which TiO(2) modified with PMMA are dispersed in tetrachloroethylene (TCE) using a mixture of oil blue dyes and charge control additive (span80). Rotary viscometer, Fourier transform infrared spectroscopy (FT-IR) and optical microscopy are used to characterize the particles, respectively. The electrophoretic mobility of the microcapsules to electric field is also investigated with two parallel electrodes.

Capsules↗
PubMed2005

The relation between narrow-dispersed microcapsules and surfactants.

Electric ink display is one of the prospect technologies in paper-like display. In this paper, electric ink microcapsules are prepared by means of an in situ polymerization and complex coacervation. In order to obtain the microcapsules in a uniform size distribution, this study focused on the inter-facial tension between tetrachloroethylene and water solution, the dispersion of the core droplets and the microencapsulation with different kind of surfactants. By measuring the inter-facial tensions between water and tetrachloroethylene, it is found that urea-formaldehyde (UF) pre-polymer presents certain surface activity due to the inter-facial tension descending from 43 mN m(-1) to 35 mN m(-1). Because the surface activity of pre-polymer is not valid, the water-soluble emulsifiers can occupy on the surface of the droplets and prevent the UF resin depositing there. The analysis of the size distribution shows that the UF microcapsules are multi-dispersed. Furthermore, the influence of anionic surfactant of SDS on the size distribution of the core droplets is also investigated. The average diameters of the core droplets prepared with 0.005 wt% and 0.012 wt% SDS are approximately 50 microm and 28 microm, respectively. That reveals the existence of SDS not only decreases the droplet diameters, but also makes the size distribution centralized. Because the surface of the core droplets is charged due to the absorption of SDS anionic, the Gelatin and Gum Arabic (GA) coacervating layer is easy to form there. The size of the GA microcapsules prepared with 0.003 wt% SDS is approximately 65 microm. Finally; the responsive behaviour of the microcapsules to electric field is also investigated.

Capsules↗
PubMed2002

In situ sol-gel preparation of polysaccharide/titanium oxide hybrid colloids and their electrorheological effect.

A new type of organic/inorganic hybrid colloid, made of modified carboxylmethyl starch (CMS) and titanium oxide (TiO(2)), was synthesized by an in situ sol-gel technique. IR spectra analysis shows strong a interaction of functional groups between two components, whose dispersion is almost at the molecular level. Due to the highly active surfaces hybrid particles and their characteristic dielectric behavior in accordance with the previous theoretic calculation, the suspensions of hybrids in silicone oil display a remarkable ER effect. The static yield stress can be above 20 kPa (shear rate 5 S(-1)) under a direct current field of 4 kV/mm at room temperature, much higher than that of simple blends of starch and titanium dioxide. In the meanwhile, the temperature dependence and sedimentation stability were optimized. Based on existing experimental results, we propose that dielectric properties and surface (interface) activity are two necessary conditions fulfilling the requirement of high ER activity. The combination of both factors may effectively reduce the activation energy needed for ERF restructuring.

Journal Article↗
PubMed2002

Spastic paraplegia, ataxia, mental retardation (SPAR): a novel genetic disorder.

OBJECTIVE: To describe a kindred with a dominantly inherited neurologic disorder manifested either as uncomplicated spastic paraplegia or ataxia, spastic paraplegia, and mental retardation. METHODS: Neurologic examinations and molecular genetic analysis (exclusion of known SCA and HSP genes and loci; and trinucleotide repeat expansion detection [RED]) were performed in six affected and four unaffected subjects in this family. MRI, electromyography (EMG), and nerve conduction studies were performed in three affected subjects. RESULTS: The phenotype of this dominantly inherited syndrome varied in succeeding generations. Pure spastic paraplegia was present in the earliest generation; subsequent generations had ataxia and mental retardation. MRI showed marked atrophy of the spinal cord in all patients and cerebellar atrophy in those with ataxia. Laboratory analysis showed that the disorder was not caused by mutations in genes that cause SCA-1, SCA-2, SCA-3, SCA-6, SCA-7, SCA-8, and SCA-12; not linked to other known loci for autosomal dominant ataxia (SCA-4, SCA-5, SCA-10, SCA-11, SCA-13, SCA-14, and SCA-16); and not linked to known loci for autosomal dominant hereditary spastic paraplegia (HSP) (SPG-3, SPG-4, SPG-6, SPG-8, SPG-9, SPG-10, SPG-12, and SPG-13) or autosomal recessive HSP SPG-7. Analysis of intergenerational differences in age at onset of symptoms suggests genetic anticipation. Using RED, the authors did not detect expanded CAG, CCT, TGG, or CGT repeats that segregate with the disease. CONCLUSIONS: The authors describe an unusual, dominantly inherited neurologic disorder in which the phenotype (pure spastic paraplegia or spastic ataxia with variable mental retardation) differed in subsequent generations. The molecular explanation for apparent genetic anticipation does not appear to involve trinucleotide repeat expansion.

Adolescent↗
PubMed1998

Dispersed repetitive DNA has spread to new genomes since polyploid formation in cotton.

Polyploid formation has played a major role in the evolution of many plant and animal genomes; however, surprisingly little is known regarding the subsequent evolution of DNA sequences that become newly united in a common nucleus. Of particular interest is the repetitive DNA fraction, which accounts for most nuclear DNA in higher plants and animals and which can be remarkably different, even in closely related taxa. In one recently formed polyploid, cotton (Gossypium barbadense L.; AD genome), 83 non-cross-hybridizing DNA clones contain dispersed repeats that are estimated to comprise about 24% of the nuclear DNA. Among these, 64 (77%) are largely restricted to diploid taxa containing the larger A genome and collectively account for about half of the difference in DNA content between Old World (A) and New World (D) diploid ancestors of cultivated AD tetraploid cotton. In tetraploid cotton, FISH analysis showed that some A-genome dispersed repeats appear to have spread to D-genome chromosomes. Such spread may also account for the finding that one, and only one, D-genome diploid cotton, Gossypium gossypioides, contains moderate levels of (otherwise) A-genome-specific repeats in addition to normal levels of D-genome repeats. The discovery of A-genome repeats in G. gossypioides adds genome-wide support to a suggestion previously based on evidence from only a single genetic locus that this species may be either the closest living descendant of the New World cotton ancestor, or an adulterated relic of polyploid formation. Spread of dispersed repeats in the early stages of polyploid formation may provide a tag to identify diploid progenitors of a polyploid. Although most repetitive clones do not correspond to known DNA sequences, 4 correspond to known transposons, most contain internal subrepeats, and at least 12 (including 2 of the possible transposons) hybridize to mRNAs expressed at readily discernible levels in cotton seedlings, implicating transposition as one possible mechanism of spread. Integration of molecular, phylogenetic, and cytogenetic analysis of dispersed repetitive DNA may shed new light on evolution of other polyploid genomes, as well as providing valuable landmarks for many aspects of genome analysis.

Amino Acid Sequence↗
PubMed1997

Positional cloning of novel skin-specific genes from the human epidermal differentiation complex.

The epidermal differentiation complex, located on human chromosomal band 1q21, contains at least 20 genes expressed during epidermal differentiation. We constructed a 1.2-Mb YAC contig spanning the SPRR and S100 gene clusters. Restriction mapping and FISH confirmed the colinearity of the contig with the genomic restriction map (A. Volz et al., 1993, Genomics 18:92-99). However, the YAC clones revealed several additional restriction sites not previously detected in genomic DNA, presumably due to CpG methylation. Making use of cDNA selection, we have identified three novel cDNAs, all of which map to the SPRR/IVL region. All three transcripts are expressed at high levels in normal and psoriatic skin, but not in cultured keratinocytes or in a variety of cell lines and human tissues. The molecular cloning of this region provides a valuable tool for identifying additional epidermal differentiation genes and for elucidating the relationship between chromatin structure and gene expression during terminal differentiation.

Amino Acid Sequence↗
PubMed1996

Effects of calcitonin injected into various brain areas on pain threshold and Ca2+ in rats.

AIM: To study the effects of calcitonin (Cal) injected into different brain areas on pain threshold. METHODS: The analgesic effects of Cal were investigated in rats by the tail-flick test. RESULTS: Cal injected into lateral cerebral ventricle (LCV) or periaqueductal gray (PAG) increased obviously the pain threshold to 49 +/- 22% or to 68 +/- 12% (P < 0.01), respectively. When PAG was blocked with lidocaine, the analgesic effect of Cal injected into LCV was lowered 41 +/- 9%. Cal injected into habenula (Hab) decreased the pain threshold to -30 +/- 5% (P < 0.01). CONCLUSION: Cal in different rat brain areas induced different effects on pain responses: analgesia or hyperalgesia, and showed that PAG played an important role in the analgesic effect induced by Cal, and the changing of pain threshold was mediated by the Ca2+ in brain.

Analgesics, Non-Narcotic↗
PubMed1995

Infectivity and risk factors of hepatitis C virus transmission through sexual contact.

HCV infection among heterosexuals with multiple partners and family members of patients with hepatitis C, and HCV RNA in the body fluid of these patients were investigated. The results showed that the HCV infection in heterosexuals with multiple partners, which was related to sexual activity, was much higher than that of healthy pregnant women. The HCV RNA in the saliva, semen or vaginal discharge of patients with hepatitis C was at detectable level. Among the patient's relatives, none of the children but 2 spouses were found to be infected with HCV. We concluded that sexual contact might play some role in HCV transmission.

Adolescent↗
PubMed1992

[Central analgesic action of calcitonin and its relationship with central monoamine transmitters].

The analgesic action of calcitonin (0.25 MRC units.kg-1) injected into lateral cerebral ventricle was investigated in rats. The pain threshold was evaluated by the tail-flick test. The influences of icv naloxone 5 micrograms/rat, a blocker of opiate receptor, on the analgesic action of calcitonin were observed. The results showed that icv calcitonin produced a significant analgesic action, which was reversed by naloxone. While the pain threshold was raised by calcitonin, the contents of central monoamines (5-HT, NE, DA) in brain (diencephalon, brain stem) were examined by fluorophotometry, which were increased remarkably. It is suggested that calcitonin-induced analgesia is related to the opiate receptors and the contents of 5-HT, NE, and DA in CNS.

Analgesics↗