Biomedical subjects

S Zhang

Publications and source records attributed to S Zhang.

At least 307 records · Page 17Linked to original sources

PubMed2000

Vaccination of domestic pig with recombinant paramyosin. against Schistosoma japonicum in China.

Paramyosin (PM), a myosin-like protein is a major antigen on Schistosoma japonicum (Sj). We reported that passive transfer of a monoclonal IgE SjE18varepsilon.1 which recognizes PM of Sj (SJPM), partially protected mice from challenge infection. In the present study, we developed an experimental model system of schistosomiasis japonica with domestic pigs in China and used it for the evaluation of vaccination with recombinant SJPM (rSJPM). Sixteen-week-old pigs were successfully infected by dermal penetration of 120 cercariae of a domestic strain of Sj (50-60% worm recovery 11 weeks after challenge). The pigs vaccinated with 400 UV attenuated cercariae showed a reduction of worm recovery (53%, p<0.001). The experimental groups were immunized intradermally with rSJPM and alum or TiterMax and were partially protected against the challenge infection (32-35% reduction).

Adjuvants, Immunologic↗

PubMed2000

Electrospray ionization mass spectrometric analyses of phospholipids from INS-1 insulinoma cells: comparison to pancreatic islets and effects of fatty acid supplementation on phospholipid composition and insulin secretion.

Insulin secretion by pancreatic islet beta-cells is impaired in diabetes mellitus, and normal beta-cells are enriched in phospholipids with arachidonate as sn-2 substituent. Such molecules may play structural roles in exocytotic membrane fusion or serve as substrates for phospholipases activated by insulin secretagogues. INS-1 insulinoma cells respond to secretagogues and permit the study of effects of culture with free fatty acids on phospholipid composition and secretion. INS-1 cell glycerophosphocholine (GPC) and glycerophosphoethanolamine (GPE) lipids are demonstrated here by electrospray ionization mass spectrometry to contain a lower fraction of molecules with arachidonate and a higher fraction with oleate as sn-2 substituent than native islets. Palmitic acid supplementation induces little change in these INS-1 cell lipids, but supplementation with linoleate or arachidonate induces a large rise in the fraction of INS-1 cell GPC species with polyunsaturated sn-2 substituents and a fall in oleate-containing species to yield a GPC profile similar to native islets. The fraction of GPE lipids comprised of plasmenylethanolamine species with polyunsaturated sn-2 substituents in early-passage INS-1 cells is similar to that of islets, but declines on serial passage. Such molecules might participate in exocytotic membrane fusion, and late-passage INS-1 cells have reduced insulin secretory responses. Arachidonate supplementation induces a rise in the fraction of INS-1 cell GPE lipids with polyunsaturated sn-2 substituents and partially restores responses to insulin secretagogues by late-passage INS-1 cells, but does not further amplify secretion by early-passage cells. Effects of extracellular free fatty acids on beta-cell phospholipid composition and secretory responses could be involved in changes in beta-cell function during the period of hyper-free fatty acidemia that precedes diabetes mellitus.

Animals↗

PubMed2000

Tea polyphenols down-regulate the expression of the androgen receptor in LNCaP prostate cancer cells.

Androgens via their cognate receptor may be involved in the development and progression of prostate cancer. The aim of this study was to determine whether tea polyphenols have inhibitory effects on androgen action in an androgen-responsive, prostate cancer cell line, LNCaP. The tea polyphenol, EGCG, inhibited LNCaP cell growth and the expression of androgen regulated PSA and hK2 genes. Moreover, EGCG had a significant inhibitory effect on the androgenic inducibility of the PSA promoter. Immunoblotting detected a decrease in androgen receptor protein with treatments of the tea polyphenols EGCG, GCG and theaflavins. Northern blot analysis showed decreased levels of androgen receptor mRNA by EGCG. Transient transfections demonstrated that EGCG and theaflavins could repress the transcriptional activities of the androgen receptor promoter region. An Sp1 binding site in the androgen receptor gene promoter is an important regulatory component for its expression. This study suggests Sp1 is the target for the tea polyphenols because treatments of EGCG decreased the expression, DNA binding activity and transactivation activity of Sp1 protein. In conclusion, we have described a new property of tea polyphenols that inhibits androgen action by repressing the transcription of the androgen receptor gene.

5' Untranslated Regions↗

PubMed2000

[Isolation and purification of Lycium barbarum polysaccharides and its antifatigue effect].

A purified component of lycium barbarum polysaccharide (LBP-X) was isolated from lycium barbarum L. by DEAE ion-exchange cellulose and sephacryl gel chromatography. LBP-X was tested on five different doses (5, 10, 20, 50 and 100 mg.kg-1.d-1) in mice. The results showed that LBP-X induced a remarkable adaptability to exercise load, enhanced resistance and accelerated elimination of fatigue. LBP-X could enhance the storage of muscle and liver glycogen, increase the activity of LDH before and after swimming, decrease the increase of blood urea nitrogen (BUN) after strenuous exercise, and accelerate the clearance of BUN after exercise. The dosage of LBP-X 10 mg.kg-1.d-1 was the best amount among the five tested doses.

Animals↗

PubMed2000

Fullerene-sensitized

[reaction: see text] Fullerene catalyzes the cycloaddition of dimethyliminodiacetate to maleimides under photolysis to form 2,5-dimethoxycarbonylpyrrolidine derivatives.

Journal Article↗

PubMed2000

Honeybee navigation: nature and calibration of the "odometer".

There are two theories about how honeybees estimate the distance to food sources. One theory proposes that distance flown is estimated in terms of energy consumption. The other suggests that the cue is visual, and is derived from the extent to which the image of the world has moved on the eye during the trip. Here the two theories are tested by observing dances of bees that have flown through a short, narrow tunnel to collect a food reward. The results show that the honeybee's "odometer" is visually driven. They also provide a calibration of the dance and the odometer in visual terms.

Animals↗

PubMed2000

Characterization, chromosomal assignment, and tissue expression of a novel human gene belonging to the ARF GAP family.

We have identified and characterized a novel human ADP-ribosylation factor GTPase-activating protein (ARFGAP1) gene that is related to other members of the ARF GAP family. The full-length cDNA for human ARFGAP1 was cloned following the identification of an EST obtained by large-scale cDNA library sequencing through a Blast search of public databases. Structurally, ARFGAP1 encodes a polypeptide of 516 amino acids, which contained a typical GATA-1-type zinc finger motif (CXXCX(16)CXXC) with the four cysteine residues that are highly conserved among other members of the ARF GAP family. The conserved ARF GAP domain may emphasize the biological importance of this gene. The ARFGAP1 gene, which contained 16 exons ranging from 0.5 to 9.3 kb, was mapped to human chromosome 22q13.2-q13.3 using radiation hybridization and in silico analyses. ARFGAP1 is strongly expressed in endocrine glands and testis. Interestingly, the expression of ARFGAP1 in testis is about sixfold higher than that in ovary, indicating a possible role of ARFGAP1 in the physiological function of sperm. Expression of ARFGAP1 in four human fetal tissues and seven cancer cell lines was also detected.

ADP-Ribosylation Factors↗

PubMed2000

14-3-3 proteins block apoptosis and differentially regulate MAPK cascades.

14-3-3 family members are dimeric phosphoserine-binding proteins that participate in signal transduction and checkpoint control pathways. In this work, dominant-negative mutant forms of 14-3-3 were used to disrupt 14-3-3 function in cultured cells and in transgenic animals. Transfection of cultured fibroblasts with the R56A and R60A double mutant form of 14-3-3zeta (DN-14-3-3zeta) inhibited serum-stimulated ERK MAPK activation, but increased the basal activation of JNK1 and p38 MAPK. Fibroblasts transfected with DN-14-3-3zeta exhibited markedly increased apoptosis in response to UVC irradiation that was blocked by pre-treatment with a p38 MAPK inhibitor, SB202190. Targeted expression of DN-14-3-3eta to murine postnatal cardiac tissue increased the basal activation of JNK1 and p38 MAPK, and affected the ability of mice to compensate for pressure overload, which resulted in increased mortality, dilated cardiomyopathy and massive cardiomyocyte apoptosis. These results demonstrate that a primary function of mammalian 14-3-3 proteins is to inhibit apoptosis.

14-3-3 Proteins↗

PubMed2000

Collapse dynamics of liquid bridges investigated by time-varying magnetic levitation

Using a novel technique that facilitates temporal control over the total body force on a liquid, an unexpected scaling relationship was discovered for the collapse time of a liquid bridge. A paramagnetic liquid was suspended between the tips of two collinear rods in a strong magnetic field gradient that was adjusted to compensate gravity. A sudden change of the magnet current, corresponding to a change of Bond number, resulted in a deformation and ultimate collapse of the liquid bridge. The collapse time was found to be independent of the bridge length when other parameters were held constant.

Journal Article↗

PubMed2000

Adult herpetic laryngitis with concurrent candidal infection: a case report and literature review.

Rarely, adult herpetic laryngitis without involvement of the oropharynx has been reported. However, to our knowledge, laryngitis caused by herpes simplex virus with coexisting Candida albicans has not been reported. We report what we believe to be the first case of localized herpetic laryngitis superimposed by laryngeal Candida species infection in an immunosuppressed patient. This diagnosis was made on the basis of the findings of a laryngeal mucosal biopsy and ancillary testing using fungal stains and immunohistochemical stains for herpetic antigens. We also review the literature and discuss the clinical and diagnostic presentations, including potential pitfalls in the diagnosis.

Anti-Inflammatory Agents↗

PubMed2000

Linkage disequilibrium mapping in populations of variable size using the decay of haplotype sharing and a stepwise-mutation model.

Linkage-disequilibrium (LD) mapping is a powerful tool for fine-mapping disease genes. Recently, McPeek and Strahs [(1999) Am J Hum Genet 65:858-875] proposed a multilocus model for LD mapping based on the decay of haplotype sharing. Here we extend their approach in two ways. First, instead of assuming each marker allele has an equal chance to mutate to one of the other marker alleles, we use the stepwise-mutation model to describe the mutation process for microsatellite markers. Second, in addition to the independence model and the constant population size model they considered, we model the dependence among observed haplotypes due to population structure by using a general conditional-coalescent model with variable population size. Through simulation studies, we study the effects of the stepwise-mutation model and variable population size on the estimates of disease gene location, mutation rate, and time to the most recent common ancestor of the sampled haplotypes. We then use this method to analyze progressive myoclonus epilepsy data.

Chromosome Mapping↗

PubMed2000

Seasonality of matings and births in captive Sichuan golden monkeys (Rhinopithecus roxellana).

This study, based on three years of mating behavior observations and 10 years of birth records, reveals that Sichuan golden monkeys in captivity displayed a marked seasonality of mating behavior and births. The peak of matings occurred around October, and births occurred in March-June. The birth peak followed the mating peak by six to seven months. This seasonal cycle of matings and births was similar to observations made in the wild, where both temperature and food resources were favorable in spring. The time delay between peaks of matings and births was the approximate length of gestation, which implies that mating behavior was concentrated during the period of conception. We suggest that the peak of births in captive Sichuan golden monkeys occurred during the time of year with the most favorable environmental conditions, and the peak of matings corresponded with the period of conception.

Animals↗

PubMed2000

Analysis of acyclovir by high performance capillary electrophoresis with on-column amperometric detection.

The separation of acyclovir (ACV) by high performance capillary electrophoresis (HPCE) with on-column amperometric detection using alpha-amino-5-mercapto-3,4-dithiazole (AMD) as internal standard is described. The calibration line was linear in the range of 0.5-20 mg/L of ACV. The detection limit was 0.15 mg/L of ACV. Its recovery ranged from 98 to 101% with relative standard deviations (RSDs) from 1.9 to 3.2% (n = 5). This method was successfully used for determining ACV in some pharmaceuticals and human urine. Comparable results with HPCE with ultraviolet (UV) detection and amperometric detection were obtained.

Acyclovir↗

PubMed2000

Lomerizine, a Ca2+ channel blocker, reduces glutamate-induced neurotoxicity and ischemia/reperfusion damage in rat retina.

We examined the effects of a new Ca2+ channel blocker, lomerizine, on the intraocular hypertension-induced ischemia/reperfusion injury in rat retina and on the glutamate-induced neurotoxicity in rat cultured retinal neurons, and compared its effects with those of a Ca2+ channel blocker (flunarizine) and an N-methyl-D-aspartate receptor antagonist (MK-801). Morphometric evaluation at 7 days after ischemia/reperfusion showed that treatment with lomerizine (0.1 and 1 mg kg(-1), i.v.) prior to ischemia and again immediately after reperfusion dose-dependently reduced the retinal damage. Treatment with MK-801 (1 mg kg(-1), i.v.) before ischemia significantly reduced the resulting retinal damage. Flunarizine (0.1 and 1 mg kg(-1), i.v.) tended to reduce the retinal damage, but its effect did not reach statistical significance. In an in vitro study, pretreatment with lomerizine (0.1 and 1 microM) or flunarizine (1 microM) significantly reduced glutamate-induced neurotoxicity, the effects being concentration dependent. Lomerizine (1 microM) also exhibited protective effects against both the N-methyl-D-aspartate and kainate induced types of neurotoxicity. However, lomerizine (1 microM) had little effect on the neurotoxicity induced by ionomycin (1 microM) application. Glutamate-induced neurotoxicity was abolished by removing Ca2+ from the medium. These results indicate that lomerizine protects neuronal cells against retinal neurotoxicity both in vivo and in vitro, and that this Ca2+ channel blocker may be useful as a therapeutic drug against retinal diseases that cause neuronal injury, such as normal tension glaucoma (NTG).

Animals↗

PubMed2000

Enhanced suppression of residual water in a "270" WET sequence.

In certain water suppression experiments, the residual water, which comes from a region away from the center of the RF coil and experiences a much smaller flip angle than the designed one, may appear. The residual water in the WET sequence can be reduced significantly by using a composite 90(x)( degrees )90(y)( degrees )90(-x)( degrees )90(-y)( degrees ) pulse, which de-excites molecules experiencing a small flip angle. The composite pulse, however, has two null excitation points near on resonance, causing a severe loss of spectrum intensity and baseline distortion toward the null points. Since the residual water experiences a very small flip angle, it can be treated as a linear spin system; i.e., the intensity of the residual water is proportional to the pulse strength and width. Based on this principle, the residual water can be reduced dramatically by replacing the 90 degrees pulse in the "270" WET sequence with a 270 degrees pulse for one out of every four scans, without noticeable loss of intensity and baseline distortion.

Algorithms↗

PubMed2000

Adiabatic decoupling sidebands.

An analytical solution is given for amplitudes and phases of adiabatic decoupling sidebands as a function of spin inversion time tau. Since all the adiabatic decoupling phases theta(t, tau) refocus at two periods (2T) of the decoupling pulse, the sidebands are located at n/2T rather than at n/T as observed in other decoupling schemes. The real (R(n)(tau)) and imaginary (I(n)(tau)) amplitudes of the sidebands have symmetry R(n)(tau) = R(-n)(tau) and I(n)(tau) = -I(-n)(tau), forming a mirror image between the counterparts of the sidebands. When frequency sweep changes direction all I(n)(tau) are inverted while all R(n)(tau) remain unchanged, leading to pure absorption sidebands with two accumulations as demonstrated by Kupce and Freeman, and to an exchange of sidebands between counterparts. The sum of the real parts for sidebands n = 1 and 2 is almost a constant near on-resonance decoupling, and it increases substantially for large decoupling offsets. The phase defocusing can be minimized for all decoupling offsets by inserting an initial decoupling period with T(ini) = T/2, eliminating all sidebands located at n/2T (n = +/-1, +/-3, +/-5, ...).

Glycine↗

PubMed2000

Synchronized adiabatic decoupling.

A new decoupling scheme termed "synchronized adiabatic decoupling" is developed for use in the indirectly detected dimension. After each increment, the decoupling sequence is replaced by another one with different period T or different initial period T(ini) so that sampling always occurs at the end of a complete decoupling period. The effects of J coupling are therefore completely averaged out for all data points. As a result, all decoupling sidebands disappear and the center band increases correspondingly. Since the synchronized adiabatic decoupling does not require conventional editing techniques to cancel the sidebands, it is useful in high-field gradient-enhanced multidimensional experiments with only a single scan per increment.

Algorithms↗

PubMed2000

The Alzheimer's peptide a beta adopts a collapsed coil structure in water.

The self-assembly of the soluble peptide Abeta into Alzheimer's disease amyloid is believed to involve a conformational change. Hence the solution conformation of Abeta is of significant interest. In contrast to studies in other solvents, in water Abeta is collapsed into a compact series of loops, strands, and turns and has no alpha-helical or beta-sheet structure. Conformational stabilization is primarily attributed to van der Waals and electrostatic forces. A large conspicuous uninterrupted hydrophobic patch covers approximately 25% of the surface. The compact coil structure appears meta-stable, and because fibrillization leads to formation of intermolecular beta-sheet secondary structure, a global conformational rearrangement is highly likely. A molecular hypothesis for amyloidosis includes at least two primary driving forces, changes in solvation thermodynamics during formation of amyloid deposits and relief of internal conformational stress within the soluble precursor during formation of lower-energy amyloid fibrils.

Amyloid beta-Peptides↗