Biomedical subjects

Y He

Publications and source records attributed to Y He.

At least 145 records · Page 8Linked to original sources

PubMed2000

TGF-alpha antisense gene therapy inhibits head and neck squamous cell carcinoma growth in vivo.

Unlike normal mucosal squamous epithelial cells, head and neck squamous cell carcinomas (HNSCCs) overexpress TGF-alpha mRNA and protein which is required to sustain the proliferation of HNSCC cells in vitro. To determine whether TGF-alpha expression contributes to tumor growth in vivo, cationic liposome-mediated gene transfer was used to deliver an antisense expression construct targeting the human TGF-alpha gene into human head and neck tumor cells, grown as subcutaneous xenografts in nude mice. The TGF-alpha antisense gene was immediately detected in the cytoplasm of the tumor cells, translocated to the nucleus by 12 h and remained localized to the nucleus for up to 3 days. Direct inoculation of the TGF-alpha antisense (but not the corresponding sense) construct into established HNSCC tumors resulted in inhibition of tumor growth. Sustained antitumor effects were observed for up to 1 year after the treatments were discontinued. Down-modulation of TGF-alpha was accompanied by increased apoptosis in vivo. These experiments indicate that interference with the TGF-alpha/EGFR autocrine signaling pathway may be an effective therapeutic strategy for cancers which overexpress this ligand/receptor pair.

Animals↗

PubMed2000

Mutations affecting the development of the peripheral nervous system in Drosophila: a molecular screen for novel proteins.

In our quest for novel genes required for the development of the embryonic peripheral nervous system (PNS), we have performed three genetic screens using MAb 22C10 as a marker of terminally differentiated neurons. A total of 66 essential genes required for normal PNS development were identified, including 49 novel genes. To obtain information about the molecular nature of these genes, we decided to complement our genetic screens with a molecular screen. From transposon-tagged mutations identified on the basis of their phenotype in the PNS we selected 31 P-element strains representing 26 complementation groups on the second and third chromosomes to clone and sequence the corresponding genes. We used plasmid rescue to isolate and sequence 51 genomic fragments flanking the sites of these P-element insertions. Database searches using sequences derived from the ends of plasmid rescues allowed us to assign genes to one of four classes: (1) previously characterized genes (11), (2) first mutations in cloned genes (1), (3) P-element insertions in genes that were identified, but not characterized molecularly (1), and (4) novel genes (13). Here, we report the cloning, sequence, Northern analysis, and the embryonic expression pattern of candidate cDNAs for 10 genes: astray, chrowded, dalmatian, gluon, hoi-polloi, melted, pebble, skittles, sticky ch1, and vegetable. This study allows us to draw conclusions about the identity of proteins required for the development of the nervous system in Drosophila and provides an example of a molecular approach to characterize en masse transposon-tagged mutations identified in genetic screens.

Animals↗

PubMed2000

Isolation and complete nucleotide sequence of a Chinese Sindbis-like virus.

Infection with alphaviruses is common in the Chinese population. Here we report the isolation of a Sindbis-like virus from a pool of Anopheles mosquitoes collected in Xinjiang, China during an arbovirus survey. This virus, designated XJ-160, rapidly produced cytopathic effects on mosquito and hamster cells. In addition, it was lethal to neonatal mice if inoculated intracerebrally. Serologically, XJ-160 reacted with and was neutralized by an anti-Sindbis antibody. Anti-XJ-160 antibodies were found in several cohorts of Chinese subjects. The complete 11626-base nucleotide sequence of XJ-160 was determined. XJ-160 has diverged significantly from the prototype Sindbis virus, with an 18% difference in nucleotide sequence and an 8.6% difference in amino acids; there are 11 deletions and 2 insertions, involving 99 nucleotides in total. XJ-160 is most closely linked to Kyzylagach virus isolated in Azerbaijan. Both belong to the African/European genetic lineage of Sindbis virus, albeit more distantly related to other members.

Alphavirus Infections↗

PubMed2000

Deficiency in fatty acid synthase leads to premature cell death and dramatic alterations in plant morphology.

An Arabidopsis mosaic death1 (mod1) mutant, which has premature cell death in multiple organs, was isolated. mod1 plants display multiple morphological phenotypes, including chlorotic and curly leaves, distorted siliques, premature senescence of primary inflorescences, reduced fertility, and semidwarfism. The phenotype of the mod1 mutant results from a single nuclear recessive mutation, and the MOD1 gene was isolated by using a map-based cloning approach. The MOD1 gene encodes an enoyl-acyl carrier protein (ACP) reductase, which is a subunit of the fatty acid synthase complex that catalyzes de novo synthesis of fatty acids. An amino acid substitution in the enoyl-ACP reductase of the mod1 mutant causes a marked decrease in its enzymatic activity, impairing fatty acid biosynthesis and decreasing the amount of total lipids in mod1 plants. These results demonstrate that a deficiency in fatty acid biosynthesis has pleiotropic effects on plant growth and development and causes premature cell death.

Arabidopsis↗

PubMed2000

2'-Deoxy-5-methylisocytidine.

In the title compound, 2-amino-1-(2-deoxy-beta-D-erythro-pentofuranosyl)-5-methylpyrimidin++ +-4 (1H)-one, C(10)H(15)N(3)O(4), the conformation of the N-glycosidic bond is syn and the 2-deoxyribofuranose moiety adopts an unusual (O)T(1) sugar pucker. The orientation of the exocyclic C4'-C5' bond is +sc (+gauche).

Crystallography, X-Ray↗

PubMed2000

Purification, crystallization and initial X-ray analysis of the head-tail connector of bacteriophage phi29.

The head-tail connector of bacteriophage phi29, an oligomer of gene product 10 (gp10), was crystallized into various forms. The most useful of these were an orthorhombic P22(1)2(1) form (unit-cell parameters a = 143.0, b = 157.0, c = 245.2 A), a monoclinic C2 form (a = 160.7, b = 143.6, c = 221.0 A, beta = 97.8 degrees ) and another monoclinic C2 form (a = 177.0, b = 169.1, c = 185.2 A, beta = 114.1 degrees ). Frozen crystals diffracted to about 3.2 A resolution. There is one connector per crystallographic asymmetric unit in each case. Rotation functions show the connector to be a dodecamer. Translation functions readily determined the position of the 12-fold axis in each unit cell. The structure is being determined by 12-fold electron-density averaging within each crystal and by averaging between the various crystal forms.

Bacillus Phages↗

PubMed2000

Overexpression of protective antigen as a novel approach to enhance vaccine efficacy of Brucella abortus strain RB51.

Brucella abortus strain RB51 is an attenuated rough strain that is currently being used as the official live vaccine for bovine brucellosis in the United States and several other countries. We reasoned that overexpression of a protective antigen(s) of B. abortus in strain RB51 should enhance its vaccine efficacy. To test this hypothesis, we overexpressed Cu/Zn superoxide dismutase (SOD) protein of B. abortus in strain RB51. This was accomplished by transforming strain RB51 with a broad-host-range plasmid, pBBR1MCS, containing the sodC gene along with its promoter. Strain RB51 overexpressing SOD (RB51SOD) was tested in BALB/c mice for its ability to protect against challenge infection with virulent strain 2308. Mice vaccinated with RB51SOD, but not RB51, developed antibodies and cell-mediated immune responses to Cu/Zn SOD. Strain RB51SOD vaccinated mice developed significantly (P < 0.05) more resistance to challenge than those vaccinated with strain RB51 alone. The presence of the plasmid alone in strain RB51 did not alter its vaccine efficacy. Also, overexpression of SOD did not alter the attenuation characteristic of strain RB51.

Animals↗

PubMed2000

Brucella abortus strain RB51 as a vector for heterologous protein expression and induction of specific Th1 type immune responses.

Brucella abortus strain RB51 is a stable, rough, attenuated mutant widely used as a live vaccine for bovine brucellosis. Our ultimate goal is to develop strain RB51 as a preferential vector for the delivery of protective antigens of other intracellular pathogens to which the induction of a strong Th1 type of immune response is needed for effective protection. As a first step in that direction, we studied the expression of a foreign reporter protein, beta-galactosidase of Escherichia coli, and the 65-kDa heat shock protein (HSP65) of Mycobacterium bovis in strain RB51. We cloned the promoter sequences of Brucella sodC and groE genes in pBBR1MCS to generate plasmids pBBSODpro and pBBgroE, respectively. The genes for beta-galactosidase (lacZ) and HSP65 were cloned in these plasmids and used to transform strain RB51. An enzyme assay in the recombinant RB51 strains indicated that the level of beta-galactosidase expression is higher under the groE promoter than under the sodC promoter. In strain RB51 containing pBBgroE/lacZ, but not pBBSODpro/lacZ, increased levels of beta-galactosidase expression were observed after subjecting the bacteria to heat shock or following internalization into macrophage-like J774A.1 cells. Mice vaccinated with either of the beta-galactosidase-expressing recombinant RB51 strains developed specific antibodies of predominantly the immunoglobulin G2a (IgG2a) isotype, and in vitro stimulation of their splenocytes with beta-galactosidase induced the secretion of gamma interferon (IFN-gamma), but not interleukin-4 (IL-4). A Th1 type of immune response to HSP65, as indicated by the presence of specific serum IgG2a, but not IgG1, antibodies, and IFN-gamma, but not IL-4, secretion by the specific-antigen-stimulated splenocytes, was also detected in mice vaccinated with strain RB51 containing pBBgroE/hsp65. Studies with mice indicated that expression of beta-galactosidase or HSP65 did not alter either the attenuation characteristics of strain RB51 or its vaccine efficacy against B. abortus 2308 challenge.

Animals↗

PubMed2000

Complementation of Brucella abortus RB51 with a functional wboA gene results in O-antigen synthesis and enhanced vaccine efficacy but no change in rough phenotype and attenuation.

Brucella abortus RB51 is a stable rough, attenuated mutant vaccine strain derived from the virulent strain 2308. Recently, we demonstrated that the wboA gene in RB51 is disrupted by an IS711 element (R. Vemulapalli, J. R. McQuiston, G. G. Schurig, N. Srirauganathan, S. M. Halling, and S. M. Boyle, Clin. Diagn. Lab. Immunol. 6:760-764, 1999). Disruption of the wboA gene in smooth, virulent B. abortus, Brucella melitensis, and Brucella suis results in rough, attenuated mutants which fail to produce the O polysaccharide (O antigen). In this study, we explored whether the wboA gene disruption is responsible for the rough phenotype of RB51. We complemented RB51 with a functional wboA gene, and the resulting strain was designated RB51WboA. Colony and Western blot analyses indicated that RB51WboA expressed the O antigen; immunoelectron microscopy revealed that the O antigen was present in the cytoplasm. Crystal violet staining, acryflavin agglutination, and polymyxin B sensitivity studies indicated that RB51WboA had rough phenotypic characteristics similar to those of RB51. Bacterial clearance studies of BALB/c mice indicated no increase in the survival ability of RB51WboA in vivo compared to that of RB51. Vaccination of mice with live RB51WboA induced antibodies to the O antigen which were predominantly of the immunoglobulin G2a (IgG2a) and IgG3 isotypes. After in vitro stimulation of splenocytes with killed bacterial cells, quantitation of gamma interferon in the culture supernatants indicated that RB51WboA immunization induced higher levels of gamma interferon than immunization with RB51. Mice vaccinated with RB51WboA were better protected against a challenge infection with the virulent strain 2308 than those vaccinated with RB51. These studies indicate that in addition to the disruption of the wboA gene there is at least one other mutation in RB51 responsible for its rough phenotype. These studies also suggest that the expressed O antigen in RB51WboA is responsible either directly or indirectly for the observed enhancement in the T-cell response.

Animals↗

PubMed2000

Deletion of the murine Duffy gene (Dfy) reveals that the Duffy receptor is functionally redundant.

All of the antigenic determinants of the Duffy blood group system are in a glycoprotein (gp-Fy), which is encoded by a single-copy gene (FY) located on chromosome 1. gp-Fy is also produced in several cell types, including endothelial cells of capillary and postcapillary venules, the epithelial cell of kidney collecting ducts, lung alveoli, and the Purkinje cells of the cerebellum. This protein, which spans the cell membrane seven times, is a member of the superfamily of chemokine receptors and a malarial parasite receptor. The mouse Duffy gene (Dfy) homolog of human FY is also a single-copy gene, which maps in a region of conserved synteny with FY and produces a glycoprotein with 60% homology to the human protein. The mouse Duffy-like protein also binds chemokines. To study the biological role of gp-Fy, we generated a mouse strain in which Dfy was deleted. These homozygous Dfy(-/-) mice were indistinguishable in size, development, and health from wild-type and heterozygous littermates. We also examined components of the immune system and found no differences in lymph nodes or peripheral blood leukocyte levels between knockout and wild-type mice. The gross and histological anatomy of the thymus, spleen, lung, and brain showed no significant differences between mutants and wild-type mice. There was no indication of an overall difference between the knockout and wild-type mice in systematic neurological examinations. The only significant difference between Dfy(-/-) and Dfy(+/+) mice that we found was in neutrophil migration in peritoneal inflammations induced by lipopolysaccharide and thioglycolate. In mice homozygous for the deletion, there was less neutrophil recruitment into the peritoneal cavity and neutrophil influx in the intestines and lungs than in wild-type mice. Despite this, the susceptibility to Staphylococcus aureus infection was the same in the absence and in the presence of gp-Fy. Our results indicate that gp-Fy is functionally a redundant protein that may participate in the neutrophil migratory process.

Alleles↗

PubMed2000

A role of angiotensin-converting enzyme gene polymorphism in left ventricular remodeling after myocardial infarction.

BACKGROUND: Left ventricular remodeling (LVR) process is one of the important secondary sequele after acute myocardial infarction (AMI). However, little is known about the relationship between LVR and angiotensin converting enzyme (ACE) gene polymorphism as well as endothelial nitric oxide synthase (ecNOS) gene polymorphism. METHODS: Coronary angiography and left ventriculography were performed within 24 hours and 30+/-7 days after AMI onset. All consecutive 24 patients (57+/-6 years) had acute anterior MI with one vessel disease of left anterior descending artery and successful revascularization therapy during acute phase. Patients were divided into three groups according to the change of end-diastolic volume index (EDVI)(Delta EDVI = EDVI 1 month-EDVI within 24 hrs); LVR(+) (Delta EDVI>7.0 ml/m(2), n = 5), LVR (-)(Delta EDVI<-7.0 ml/m(2), n = 13), and LVR (+/-)(-7.0<Delta EDVI<7.0 ml/m(2), n = 6) groups. The polymorphisms of ACE and ecNOS gene were determined with PCR method after an extraction of genomic DNA from peripheral leukocytes. RESULTS: There were no significant difference among three groups as to baseline characteristics, including coronary risk factors, medications, serum CPKmax and patency of infarct-related artery. The incidence of DD genotype of ACE gene is significantly higher in LVR (+) than in the other two groups (0.60; 0; 0, respectively, chi(2) = 13.150, p<0.01). The incidence of D allele of ACE gene is also significantly higher in LVR (+) than in the other two groups (0.70; 0.17; 0.19, respectively, chi(2) = 10.221, p<0.01). Delta EDVI of DD genotype was significantly greater than in the other two groups (DD genotype = 30.1+/-18.1; ID genotype = -13.0+/-27.4; II genotype = -8.2+/-11.5 ml/m(2), respectively, p<0.05). There was no significant difference in ecNOS gene polymorphism among three groups. By stepwise regression analysis, the significant independent predictors of Delta EDVI were EDVI within 24 hrs and DD genotype (F = 16.88 and 8.641, respectively, p = 0.0024). CONCLUSION: These results showed that left ventricular dilatation is related to DD genotype of ACE gene after successful reperfusion therapy of anterior AMI. Thus, renin-angiotensin system may play an important role in left ventricular remodeling after AMI.

Aged↗

PubMed2000

[Bone marrow transplantation for beta-thalassemia major].

OBJECTIVE: To examine the feasibility of bone marrow hematopoietic stem cell transplantation for thalassemia major. METHODS: Bone marrow transplantation was performed on a 4-year-old patient with beta-thalassemia major, whose gene mutation was CD41-42/654. The donor was his brother. In the 850ml bone marrow, the nucleated cells were 5.6x10(8)/kg, CD(+)(34) cells 7.8 x 10(6)/kg, and colony-forming-unit-granulocyte-macrophages(CFU-GM) 5.7x10(5)/kg. HLA was one site mismatched, while RBC type matched. Pre-transplant conditions included Busulfan 16mg/kg, cyclophosphamide 200mg/kg and lymphoglobuline 88mg/kg. Cyclosporine and methotrexate were used for prevention of graft-versus-host disease(GVHD). RESULTS: After transplantation, the patient had grade II acute GVHD and cytomegalovirus(CMV) interstitial pneumonia; he was cured. White blood cells(WBC) and neutrophil granulocytes recovered to 1.1 x 10(9)/L and 0.4 x10(9)/L respectively on day 14 post transplantation. WBC was 4.5 x 10(9)/L on day 18, and descended for a time during treating interstitial pneumonia with Ganciclovir. Platelet(Plt) exceeded 50 x 10(9)/L on day 86 and recovered to normal 5 mothers and a half post transplantation. Hb reached 106g/L on day 128. The patient received the last blood transfusion on day 103. Before transplantation, the patient had to receive 200ml blood infusion per month for maintaining Hb 60-90g/L; after transplantation, his Hb kept up >110g/L for 6 months without blood transfusion. The gene type had changed to donor's CD41-42/N heterozygen. CONCLUSION: This is the first report on successful transplantation of bone marrow stem cell for thalassemia major in China, suggesting a new way to treat the disease and to expand the use of BMT. For treatment of CMV interstitial pneumonia post-transplantation, Ganciclovir should be dose enough and be used for at least 2 months.

Child, Preschool↗

PubMed2000

[The influence of some factors on DNA cycle sequencing].

OBJECTIVE: To study the influence of some factors on DNA cycle sequencing. METHODS: The effects of DNA templates, primers, cycle sequencing reaction conditions as well as purification methods were comparatively analyzed. RESULTS: When the DNA concentration was low, the nucleotide curve showed low ratio of signal to noise, even there were no fluorescent signal. While DNA concentration was too high, the readable length of nucleotides was short. Ions in the DNA template could result in bad sequencing reaction. The Tm value, length and G+C content of primers had no obvious influences on sequencing reaction. The alteration of the denaturing, annealing and extension temperature, or the addition of dimethl sulfoxide or glycerin facilitated sequencing some DNA templates. The fluorescent residues in the purified products of the sequence reaction could interfere the automatic reading of the sequencer, but did not influence the manually proofreading of the sequence. CONCLUSION: The purity and concentration of DNA templates are closely related to sequence data quality. The modification of reaction parameters and usage of additives can help to obtain good result of sequencing some DNA with certain structure. The use of 70% ethanol is recommended to precipitate the extension product.

Sequence Analysis, DNA↗

PubMed2000

Secondary near-pentaploidy and/or near-tetraploidy characterized by the duplication of 8;21 translocation in the M2 subtype of acute myeloid leukemia.

Hyperploidy, especially near-tetraploidy, is rare in acute myeloid leukemia (AML). We report 2 cases with secondary hyperploidy characterized by double 8;21 translocations. Morphologic observation of bone marrow smears revealed numerous giant blasts in both cases. Chromosome analyses with R-banding technique showed a karyotype of 46,XX,t(8;21)(2%)/92,XXXX, add(7)(q31)x2,t(8;21)x2(7%)/100-117,XXX,-X,-X,-1,+4,+4,-7,+add(7)(q31)x3 , t(8;21)x2,+der(21)t(8;21),+22(90.6%)/46,XX(0.3%) in case 1 and a karyotype of 45,X,-Y,t(8;21)(15%)/90,XX,-Y,-Y,t(8;21)x2(80%)/46,XY(5%) in case 2. DNA ploidy analyses by flow cytometry showed triple peaks (diploid, tetraploid [DI 2.09] and near-pentaploid [DI 2.59]) in case 1, and double peaks (diploid and near-tetraploid [DI 2.07]) in case 2. Reverse-transcriptase polymerase chain reaction detected an AML1/ETO fusion transcript (152 bp) in both cases. This paper brings the total number of cases of secondary hyperploid t(8;21) AML to 6 and further emphasizes a correlation between hyperploidy and t(8;21) translocation.

Bone Marrow↗

PubMed2000

[Application of Conners Rating Scales in the study of lead exposure and behavioral effects in children].

OBJECTIVE: To seek specific indices reflecting individual level of long-term exposure to lead and its behavioral effects. METHODS: Ninety-eight children of grades one to four in primary schools in the areas polluted by lead were chosen as exposed group and 100 children from areas without lead pollution as control group. Levels of blood lead, hair lead and blood zinc protoporphyrin (ZPP) in both groups were determined to evaluate their exposure to lead. Their urinary homovanillic acid (HVA) and vanillylmandelic acid (VMA) were determined by a method combined high-performance liquid chromatography (HPLC) with electric chemistry (EC) technique. Behavioral effects in children exposed to lead were assessed by Conners' Rating Scales for Teachers and Parents. RESULTS: Levels of blood lead, hair lead and blood ZPP in the exposed group increased to 2.39-2.42 mumol/L, 81.81-83.77 mumol/kg and 0.55-0.65 mumol/L in average, respectively, and levels of HVA and VMA decreased to 0.53 mmol/mol creatinine and 0.68 mmol/mol creatinine in average, respectively, both with a very significant difference as compared with those in the control group. There were significant differences in the scores of behavioral factors between the two groups. Factors I, IV and VI in Conners' Parents' Rating Scales correlated positively with levels of hair lead, while factors I, II, IV and VI correlated positively with blood ZPP levels in girls. CONCLUSION: Conners' Rating Scales for Teachers and Parents can be used to assess their behavioral effects in children, and levels of hair lead and blood lead can be used as good markers to reflect level of exposure to lead in children.

Attention Deficit Disorder with Hyperactivity↗

PubMed2000

[Typing of enteric adenoviruses in feces of infants with diarrhea].

OBJECTIVE: To study the infection condition of adenovirus types in infants with diarrhea in Shenzhen. METHODS: 114 fecal samples from diarrhea infants were tested by PCR. The amplified products were analyzed by Taq I and Rsa I endonucleases. RESULTS: The positive rate of adenovirus DNA in fecal samples was 14% (16/114). The amplified products typing procedure started with Taq I endonuclease to identify the type of adenovirus, 11 cleaved by Taq I yielded two fragments of 191 bp and 110 bp, the positive rate of enteric adenovirus was 9.65% (11/114). Followed by Rsa I cleavage, two amplified products yielded 256 bp and 45 bp fragments (Ad40), the positive rate of Ad40 was 1. 75% (2/114), nine amplified products yielded 211 bp and 90 bp fragments (Ad4l), the positive rate of Ad41 was 7.89%(9/114). CONCLUSIONS: The positive rates of the adenovirus types 40 and 41 were 9.65% in feces of infants with diarrhea, and that of the other types of adenovirus was 4.35%.

Adenovirus Infections, Human↗

PubMed2000

[Viral etiology study of acute conjunctivitis].

OBJECTIVE: To study the viral etiology of acute conjunctivitis broke out in Shenzhen in 1997. METHODS: Isolated the virus from eye and pharynx swabs of acute conjunctivitis in acute stage, and detected virus nucleic acid by polymerase chain reaction (PCR). DNA of viral strains were subjected to restriction enzyme analysis using several endonucleases. Also, neutralizing antibody of paired sera were detected. RESULTS: The positive virus isolation rates of 14 pharynx and eye swabs were 71.43% and 64.29%, respectively; and that of the virus DNA by PCR were 78.57% and 71.43%, respectively. All of the strains isolated were adenovirus type 3. Three paired viral strains chosen and subjected to restriction enzyme analysis proved belonging to Ad3a2 gene type. The neutralization test of paired sera of 24 cases showed that the antibody titers had 4 fold rising or above. Neutralization test of isolated viruses with paired sera of itself was carried out, the level of neutralizing antibody in convalescent stage was above 4 times as compared with that of acute stage. CONCLUSIONS: The results showed that the outbreak of acute conjunctivitis occurred in 1997 in Shenzhen was caused by adenovirus type 3.

Acute Disease↗

PubMed2000

[Biomicrocapsule membrane for cell and tissue transplantation].

OBJECTIVE: To Provide a simple and safe way in protecting living cells from immune rejection for transplantation therapies. METHODS: Enclose cells in Alginate-poly-l-lysine (APA) biomicrocapsules which have to be satisfied the following requirements: 1. biocompatibility, 2. strength, 3. permeability. RESULTS: The transplanted cells survived and had prominence therapy function in experimental animals. CONCLUSIONS: Biomicrocapsules are feasible tools for cells immune-transplantation.

Animals↗