Biomedical subjects

X L Wu

Publications and source records attributed to X L Wu.

At least 55 records · Page 3Linked to original sources

PubMed1999

[Study of formula for calculating body surface areas of the Chinese adults].

The body surface area of 100 Chinese adults (50 for each sex) was measured with the paper cast method and compared to the results estimated by the Stevenson's "height-weight-surface" formula. Our results shows that Stevenson's formula is no longer suitable for the Chinese. Our formulae for Chinese are as follows: SI=0.0061 x H + 0.0124 x W - 0.0099 (for both sexes), SII=0.0057 x H + 0.0121 - W + 0.0882 (for male), SIII=0.0073 H + 0.0127 x W - 0.2106 (for female) H: body height, W: body weight, S: body surface area

Adult↗

PubMed1999

[Determination of alkaloids in pericarpium papaveris by gas chromatography with wide bore capillary column].

A method for the simultaneous determination of codeine, morphine, thebaine, papaverine and narcotine in pericarpium papaveris by gas chromatography with wide bore capillary column is described. The major components in pericarpium papaveris were extracted with methanol and chloroform by supersonic extraction and evaporation. The residue was dissolved in methanol. The resulting solution was used for analysis. The conditions for determination were: FID detector, HP-1 capillary column, 5 m x 0.53 mm x 2.65 microns film, column temperature 260 degrees C, The method requires 10 minutes for the whole analysis. The average recoveries of codeine, morphine, thebaine, papaverine and narcotine in the sample were 94.0%, 96.5%, 93.8%, 91.0% and 91.4% respectively. The relative standard deviations were from 0.92% to 2.75%. The advantages of this method are simple, rapid, accurate and sensitive.

Alkaloids↗

PubMed1998

Design of organic molecules with large two-photon absorption cross sections.

A strategy for the design of molecules with large two-photon absorption cross sections, delta, was developed, on the basis of the concept that symmetric charge transfer, from the ends of a conjugated system to the middle, or vice versa, upon excitation is correlated to enhanced values of delta. Synthesized bis(styryl)benzene derivatives with donor-pi-donor, donor-acceptor-donor, and acceptor-donor-acceptor structural motifs exhibit exceptionally large values of delta, up to about 400 times that of trans-stilbene. Quantum chemical calculations performed on these molecules indicate that substantial symmetric charge redistribution occurs upon excitation and provide delta values in good agreement with experimental values. The combination of large delta and high fluorescence quantum yield or triplet yield exhibited by molecules developed here offers potential for unprecedented brightness in two-photon fluorescent imaging or enhanced photosensitivity in two-photon sensitization, respectively.

Aniline Compounds↗

PubMed1998

The 2 micrometer plasmid stability system: analyses of the interactions among plasmid- and host-encoded components.

The stable inheritance of the 2 micrometer plasmid in a growing population of Saccharomyces cerevisiae is dependent on two plasmid-encoded proteins (Rep1p and Rep2p), together with the cis-acting locus REP3 (STB). In this study we demonstrate that short carboxy-terminal deletions of Rep1p and Rep2p severely diminish their normal capacity to localize to the yeast nucleus. The nuclear targeting, as well as their functional role in plasmid partitioning, can be restored by the addition of a nuclear localization sequence to the amino or the carboxy terminus of the shortened Rep proteins. Analyses of deletion derivatives of the Rep proteins by using the in vivo dihybrid genetic test in yeast, as well as by glutathione S-transferase fusion trapping assays in vitro demonstrate that the amino-terminal portion of Rep1p (ca. 150 amino acids long) is responsible for its interactions with Rep2p. In a monohybrid in vivo assay, we have identified Rep1p, Rep2p, and a host-encoded protein, Shf1p, as being capable of interacting with the STB locus. The Shf1 protein expressed in Escherichia coli can bind with high specificity to the STB sequence in vitro. In a yeast strain deleted for the SHF1 locus, a 2 micrometer circle-derived plasmid shows relatively poor stability.

Activating Transcription Factors↗

PubMed1997

The 2microm-plasmid-encoded Rep1 and Rep2 proteins interact with each other and colocalize to the Saccharomyces cerevisiae nucleus.

The efficient partitioning of the 2microm plasmid of Saccharomyces cerevisiae at cell division requires two plasmid-encoded proteins (Rep1p and Rep2p) and a cis-acting locus, REP3 (STB). By using protein hybrids containing fusions of the Rep proteins to green fluorescent protein (GFP), we show here that fluorescence from GFP-Rep1p or GFP-Rep2p is almost exclusively localized in the nucleus in a cir+ strain. Nuclear localization of GFP-Rep1p and GFP-Rep2p, though discernible, is less efficient in a cir(0) host. GFP-Rep2p or GFP-Rep1p is able to promote the stability of a 2microm circle-derived plasmid harboring REP1 or REP2, respectively, in a cir(0) background. Under these conditions, fluorescence from GFP-Rep2p or GFP-Rep1p is concentrated within the nucleus, as is the case in cir+ cells. This characteristic nuclear accumulation is not dependent on the expression of the FLP or RAF1 gene of the 2microm circle. Nuclear colocalization of Rep1p and Rep2p is consistent with the hypothesis that the two proteins directly or indirectly interact to form a functional bipartite or high-order protein complex. Immunoprecipitation experiments as well as baiting assays using GST-Rep hybrid proteins suggest a direct interaction between Rep1p and Rep2p which, in principle, may be modulated by other yeast proteins. Furthermore, these assays provide evidence for Rep1p-Rep1p and Rep2p-Rep2p associations as well. The sum of these interactions may be important in controlling the effective cellular concentration of the Rep1p-Rep2p complex.

Cell Compartmentation↗

PubMed1996

Seroepidemiological survey of lymphocytic choriomeningitis virus in wild house mice in China with particular reference to their subspecies.

Serum samples from 337 wild house mice (Mus musculus) from 35 sites in China, collected in 1992 and 1993, were examined for antibodies against lymphocytic choriomeningitis virus (LCMV). Ten samples from eight sites were found to contain such antibodies. Six of the eight positive sites were located in the territory of M. m. gansuensis. One of the other two sites was located in the territory of M. m. castaneus in southern China and the other site was in a habitat of M. m. castaneus which had invaded into the western end of the territory of M. m. homourus. It seems likely that LCMV is distributed in the territories of M. m. gansuensis and M. m. castaneus in China. This is the first report of detection of these antibodies in wild house mice in China and specifically in the territories of M. m. gansuensis and M. m. castaneus.

Animals↗

PubMed1995

Expression of beta-actin and alpha-tubulin mRNA in gerbil brain following transient ischemia and reperfusion up to 1 month.

The time course of mRNA expressions of two cytoskeletal proteins, beta-actin and alpha-tubulin, was studied by Northern blot analysis and in situ hybridization in the same gerbil brains at various periods of recirculation following 10 min of forebrain ischemia. On Northern blot analysis, beta-actin mRNA in the forebrain showed increase after 6 h and 24 h recirculation. There was wide variation in its expression 3 days postischemia (PI), and by 7 days PI it had returned to control. The alpha-tubulin mRNA in the forebrain was shown to be reduced 6 h PI in our previous study. In the present analysis of Northern blots of delayed postischemic periods, there was no significant change in its expression even though there were variations. In situ hybridization revealed a decline in the mRNA expressions of both alpha-tubulin and beta-actin in the CA1 region as early as 6-24 h PI with the reductions being prominent at 3 days PI. By 7 days PI, beta-actin was only faintly visible while alpha-tubulin was completely absent in the CA1 region. Neither RNA was detectable in CA1 1 month PI. The heat shock-70 protein was expressed by 1 h PI, and it continued to be expressed up to 24 h, returning to control by 3 days PI. These results indicate that ischemia inhibits mRNA expressions of cytoskeletal protein in the selectively vulnerable region of the brain, i.e. CA1. The time course of the reduction of the two mRNAs coincides with delayed neuronal death suggesting that the cytoskeletal proteins may play important roles in selective postischemic neuronal injury.

Actins↗

PubMed1995

Geographical distribution of the Hbb haplotypes in the Mus musculus subspecies in eastern Asia.

We surveyed the geographical distribution of Hbb haplotypes of the house mouse, Mus musculus, in the former USSR and the northern part of China. Mice with the w1 haplotype were distributed from the coastal area of the Black Sea to the Maritime Province of Siberia in the former USSR and in the area north of the Yangtze River in China. Mice with the p haplotype were found in the areas surrounding those populated with the w1 haplotype mice. In the Maritime Province and the southern part of Siberia, the d haplotype was predominant. The correlation between the geographical variation of the Hbb haplotypes and the distribution of the Mus musculus subspecies in the eastern part of the Eurasian Continent, is discussed.

Animals↗

PubMed1994

Post-ischemic changes in protein kinase C RNA in the gerbil brain following prolonged periods of recirculation: a phosphorimaging study.

Northern blot analysis was performed to investigate the long-term changes in mRNA expression of protein kinase C (PKC) in the gerbil brain following transient cerebral ischemia. We have previously demonstrated an increase in mRNA levels of certain Ca(2+)-independent forms of PKC in early recirculation periods i.e., 6 h and 24 h postischemia (PI). But, since neuronal death in susceptible regions usually occurs 2-3 days following ischemia, this study examined the mRNA levels of PKC after prolonged periods of reperfusion following ischemia. The mRNA expression was also examined at an early recirculation period, i.e., 1 h, to determine how early the alterations begin to occur. Global forebrain ischemia was produced in gerbils by 10 min of bilateral carotid artery occlusion. RNA was prepared from forebrains of nonischemic controls and PI animals following 1 h, 3 d, and 7 d of recirculation (n = 3 to 4 in each group) and hybridized with synthetic oligonucleotide probes for PKC, delta, epsilon, and zeta based on cDNA sequences in rat and labelled with 32P. The autoradiographs were recorded and quantified by a sensitive system, Phosphor Imager, followed by conventional x-ray film exposure. The mRNA levels of all 3 PKC isozymes examined were found to be elevated as early as 1 h recirculation following ischemia. The increases in mRNA levels of both delta PKC following 6 h and 24 h of recirculation as well as that of zeta PKC following 24 h of recirculation, as reported earlier, return to control levels by 3 d PI and remain at that level 7 d PI.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Distribution of the molossinus allele of Sry, the testis-determining gene, in wild mice.

When the Y chromosome of the laboratory inbred mouse strain C57BL/6 (B6) is replaced by the Y of certain strains of Mus musculus domesticus, testis determination fails and all XY fetuses develop either as hermaphrodites or XY females (XY sex reversal). This suggests the presence of at least two alleles of Sry, the male-determining gene on the Y:M. m. domesticus and B6. The B6 Y chromosome is derived from the Japanese house mouse, M. m. molossinus and therefore carries a molossinus Sry allele. As a first step to determine how the molossinus Sry allele evolved, its distribution pattern was determined in wild mice. The cumulative data of 96 M. musculus samples obtained from 58 geographical locations in Europe, North Africa, and Asia show the molossinus Sry allele is restricted to Japan and the neighboring Asian mainland and confirm that Japanese M. m. molossinus mice were derived in part from a race of M. m. musculus from Korea or Manchuria. Sry polymorphisms, as illustrated by the molossinus Sry allele, can serve as molecular markers for studies on the evolution of wild M. musculus populations and can help determine the role sex determination plays in speciation.

Alleles↗

PubMed1994

[Treatment of pediatric late stage neuroblastoma].

From 1960 to 1992, 62 children with late stage neuroblastoma (stage III-IV) were admitted to our hospital. 24 (1960-1982) treated with operation and routine chemotherapy all died in 24 months after operation. And in 38 (1983-1993) treated with operation and high dose chemotherapy (including auto-bone-marrow transplantation + three times dose VM26 + routine chemotherapy in 3 cases, high dose chemotherapy + resection of tumor + high dose chemotherapy + routine chemotherapy for 4 years in 27, and dumbbell neuroblastoma in 8), 24 cases (63.%) still lived up to now. In which 11 cases (28.9%) lived more than 5 years and other 13 cases middle survival stage was 26.9 months. The high chemotherapy couldn't be instead of operation but it might produce a favourable condition to radical operation and thereby increase the effect of the operation.

Antineoplastic Agents↗

PubMed1992

Pharmacokinetic and pharmacodynamic studies of the effect of ketoconazole on reproductive function in male rats.

A single oral dose (300 mg kg-1) of ketoconazole induced reversible immobilization of rat epididymal spermatozoa at 8-24 h after dosing. This occurred when the drug concentrations in cauda epididymal fluid and seminal plasma were at their peak (18.0 +/- 7.3 and 13.5 +/- 3.0 micrograms ml-1, respectively), and which was preceded by a peak plasma concentration (Cmax) of 64.82 +/- 2.47 micrograms ml-1 at 5.15 +/- 0.68 h (Tmax). In contrast, rete testis fluid collected from the same animals contained only minute amounts of ketoconazole (0.47 +/- 0.34 micrograms ml-1). Plasma testosterone concentration showed a sharp decline within 4 h of dosing, followed by a recovery from suppression, even after administration of a low dose (100 mg kg-1) which did not affect sperm motility. These findings suggest that ketoconazole gains access to the post-testicular sex organs and affects the mature spermatozoa therein much more readily than it affects testicular spermatogenesis. Synthesis and screening of compounds with a related molecular structure but which exhibit more pronounced spermicidal and less pronounced anti-androgenic effects are thus suggested in the hope that rapidly acting and reversible male contraceptives might be identified and developed.

Administration, Oral↗

PubMed1992

Differential binding of (+) and (-) gossypol to plasma protein and their entry into rat testis.

Concentrations of (+) and (-) gossypol were measured by high performance liquid chromatography after they were incubated with plasma proteins in vitro. The concentration of (-) gossypol decreased more than the concentration of (+) gossypol. A similar decrease in free gossypol concentrations in the blood plasma of rats was observed after intravenous infusion of gossypol enantiomers. The concentration of (-) gossypol was also found to be lower than the concentration of (+) gossypol at the blood-testis barrier. The biological effect of (-) gossypol probably results from its stereospecific binding to extra- and intracellular proteins in vivo and inhibition of the biological activity of some proteins.

Animals↗

PubMed1991

Molecular cloning, sequencing, and expression of human myocardial fatty acid ethyl ester synthase-III cDNA.

Fatty acid ethyl ester synthase-III (FAEES-III), previously purified to homogeneity from human heart, metabolizes ethanol nonoxidatively. Using a derived partial amino acid sequence and corresponding oligonucleotide probes, the cDNA for this enzyme has been cloned from a human heart lambda gtll library. Of the five positive clones obtained, one contained a complete coding region (630 base pairs) and the entire 3'-noncoding region (41 base pairs). From this nucleotide sequence the complete 210 amino acid sequence of FAEES-III (Mr 23,307) is reported. Comparison of its amino acid sequence with that of glutathione S-transferase pi-1 suggests that they belong to the same gene family since they differ in only six nucleotides and four amino acids. The sequence of FAEES-III was also compared with those of placental glutathione S-transferase and the basic glutathione S-transferase. FAEES-III was 84% homologous with placental glutathione S-transferase but only less than 10% homologous with the basic glutathione S-transferase. Northern blots demonstrate expression of FAEES-III mRNA in normal human liver, placenta, and heart. In all cases, the mRNA for the enzyme is 0.7 kilobase in size. MCF-7 cells transfected with FAEES-III cDNA have a 14-fold increase in synthase activity and a 12-fold increase in glutathione S-transferase (GST) activity compared with control cells. MCF-7 cells transfected with GST pi-1 cDNA have a 13-fold increase in GST activity compared with control cells but no increase in synthase activity. When the supernatant of COS-7 cells transfected with FAEES-III cDNA were immunoblotted with rabbit FAEES-III antibody, a band at 24 kilodaltons was demonstrated. Thus, we have obtained the first cDNA and amino acid sequence for a human FAEES-III which also has significant GST activity, and we have identified 4 residues potentially responsible for conferring ethanol recognition to GSTs.

Acyltransferases↗

PubMed1991

Delayed-focus pulses for magnetic resonance imaging: an evolutionary approach.

An evolutionary algorithm has been used to design a family of shaped radiofrequency pulses giving uniform absorption-mode excitation across a predetermined frequency band. By allowing a free precession interval before signal acquisition, time is left for field gradients to be switched and for undesirable transients to decay.

Electromagnetic Phenomena↗

PubMed1990

Management of local residual primary lesion of nasopharyngeal carcinoma: II. Results of prospective randomized trial on booster dose.

Although the question of booster dose for residual primary lesion arises in only 5% of nasopharyngeal carcinoma patients receiving radiotherapy, it poses a difficult problem for clinicians and should be followed. Hence, to test the validity of booster dose for residual primary lesion of nasopharyngeal carcinoma, a prospective randomized trial has been designed and carried out since January 1980. All patients who had a residual lesion in the nasopharynx at 70 Gy were biopsied. Those pathologically positive for cancer were randomized into two groups: (a) positive radiation group (PRG): patients were given further irradiation to a total dose of 90 Gy by the cone-down and assault technique, and (b) positive observation group (POG): patients were given no more irradiation but were followed periodically together with those who were pathology negative (NOG). A total of 78 patients were entered. The validity of booster dose was shown by the 5-year survival rates of the PRG, POG and NOG groups: 75% (3/4), 33% (1/3), and 58% (14/24), respectively. The total local recurrence rates of these groups were 6% (1/16), 36% (5/14), and 4% (2/48), respectively. The authors believe that booster dose for pathology positive residual lesion in the nasopharynx is necessary. The four factors leading to the development of a local recurrence are: (a) residual primary lesion proved positive by pathology but left unboosted, (b) well differentiated squamous cell carcinoma in the original primary lesion, (c) mild radio-response in the cancer parenchyma, and (d) mild radio-response in the interstitial tissue.

Carcinoma, Squamous Cell↗

PubMed1990

Enhancement of the critical current density in single-crystal Bi2Sr2CaCu2O8 superconductors by chemically induced disorder.

The effect of metal substitution on the critical current densities of single-crystal PbxBi2-xSr2CaCu2O8 (x = 0 or x = 0.7) superconductors has been investigated. Substitution of lead was found to increase the average critical current density from 1 x 10(5) A/cm2 to 2 x 10(6) A/cm2 at 5 K in an applied magnetic field of 10 kilooersteds (1 oersted = 80 A/m). The order of magnitude increase in the critical current density was observed for temperatures up to the flux vortex lattice melting point; the flux lattice melting point was also found to increase to 30 K (from 22 K) in the lead-substituted materials. Diffraction and microscopy investigations of the structural parameters indicate that the fundamental atomic lattices are virtually the same for both materials. Scanning tunneling microscopy images demonstrate, however, that lead substitution causes significant disorder (or defects) in the one-dimensional superstructure found in Bi2Sr2CaCu2O8. Since crystal defects can increase the critical current density by pinning the motion of flux vortices, it is likely that this lead-induced disorder enhances vortex pinning. The lead-induced disorder is specific to the nonsuperconducting Bi-O layers, and thus our results suggest that chemical substitutions may be utilized to control selectively flux pinning and the critical current density in these materials.

Journal Article↗

PubMed1989

The entry of gossypol across the blood-testis barrier in rats.

This paper presents the experimental data about how different formulations of gossypol enter the blood-testis barrier following intravenous administration in acute experiments on rats. It was found that gossypol encapsulated by liposomes crossed the blood-testis barrier more readily than free gossypol, without affecting its pharmacokinetic pattern in the circulating blood, suggesting that liposomes may be useful as drug carriers and may facilitate the entry of encapsulated gossypol into the seminiferous tubule from the blood.

Animals↗