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Biomedical subjects

Y J Zhou

Publications and source records attributed to Y J Zhou.

36 records · Page 2Linked to original sources
PubMed1996

Rotavirus subunit vaccines.

We evaluated rotavirus subunit vaccines for use in humans and animals. Insect cells were co-infected with combinations of individual baculovirus recombinants expressing human, bovine or simian rotavirus VP2, VP4, VP6 or VP7 to produce virus-like particles (VLPs). To determine whether immunization with VLPs could induce active protective immunity, VLPs were administered parenterally to rabbits, and the immune response and protection from rabbit ALA rotavirus challenge were evaluated. Complete or partial protection was attained, showing that parenteral immunization with VLPs induces active protective immunity. We also examined whether heterotypic immune responses could be induced with a limited number of broadly reactive VP7 proteins or with chimeric particles (multiple VP7 types on individual particles). The feasibility of this approach was determined by immunizing mice with VLPs containing a G3 VP7 or G1 VP7 and chimeric G1/G3 VLPs. Broadly reactive neutralizing antibody was induced by the G1 VLPs. VLPs also have been successfully used to boost lactogenic (colostral and milk) immunity in dairy cows. Taken together, these results show that VLPs can be effective immunogens in rabbits, mice and dairy cattle when administered parenterally, a limited number of VLPs may be sufficient to produce a broadly protective vaccine, and G3 VLPs may serve as an effective subunit vaccine for use in bovines.

Animals↗
PubMed1995

[The formation of experimental periodontitis of Guinea pig]

This investigation was used silk suture and high sugar to study the formation of experimental periodontitis.The results showed that the gingival index(GI) and periodontal deep(PD) of all experimental Guinea pig were increased in the first week.There were more lymphocytes and plasmacytes in gingival proper layer in the second week.The plasmacytes and macrophages in gingival proper layer were increased much more in 4th week and alveolar bone was absorbed less,and there were more osteoclasts lying in resorpted area of alveolar bone.In the 8th week,the alveolar bone were resorpted more severe.There were more osteoblasts in the resorpted alveolar bone area besides the osteoclaste.The lysosome and endoplasmic veticulum in lymphocytes were increased.The osteoclasts near resorpted alveolar bone had several nucleus,and there were more lysosome chondriosome and endoplasmic veticulum,and the osteoclasts activity were increased,which suggests that silk suture and high sugar can form experimental periodontitis to Guinea pig and the formation time of experimental periodontitis was in the 4th week later.

Journal Article↗
PubMed1994

Localization of rotavirus VP4 neutralization epitopes involved in antibody-induced conformational changes of virus structure.

We previously characterized three neutralization-positive epitopes (NP1 [1a and 1b], NP2, and NP3) and three neutralization-negative epitopes on the simian rotavirus SA11 VP4 with 13 monoclonal antibodies (MAbs). Conformational changes occurred as a result of the binding of NP1 MAbs to the SA11 spike VP4, and enhanced binding of all neutralization-negative MAbs was observed when NP1 MAbs bound VP4 in a competitive MAb capture enzyme-linked immunosorbent assay. To further understand the structure and function of VP4, we have continued studies with these MAbs. Electron microscopic and sucrose gradient analyses of SA11-MAb complexes showed that triple-layered viral particles disassembled following treatment with NP1b MAbs 10G6 and 7G6 but not following treatment with NP1a MAb 9F6, NP2 MAb 2G4, and NP3 MAb 23. Virus infectivity was reduced approximately 3 to 5 logs by the NP1b MAbs. These results suggest that NP1b MAb neutralization occurs by a novel mechanism. We selected four neutralization escape mutants of SA11 with these VP4 MAbs and characterized them by using plaque reduction neutralization assays, hemagglutination inhibition assays, and an antigen capture enzyme-linked immunosorbent assay. These analyses support the previous assignment of the NP1a, NP1b, NP2, and NP3 MAbs into separate epitopes and confirmed that the viruses were truly neutralization escape mutants. Nucleotide sequence analyses found 1 amino acid (aa) substitution in VP8* of VP4 at (i) aa 136 for NP1a MAb mutant 9F6R, (ii) aa 180 and 183 for NP1b MAb mutants 7G6R and 10G6R, respectively, and (iii) aa 194 for NP3 MAb mutant 23R. The NP1b MAb mutants showed an unexpected enhanced binding with heterologous nonneutralization MAb to VP7 compared with parental SA11 and the other mutants. Taken together, these results suggest that the NP1b epitope is a critical site for VP4 and VP7 interactions and for virus stability.

Amino Acid Sequence↗
PubMed1994

Characterization of virus-like particles produced by the expression of rotavirus capsid proteins in insect cells.

Rotaviruses are triple-layered particles that contain four major capsid proteins, VP2, VP4, VP6, and VP7, and two minor proteins, VP1 and VP3. We have cloned each of the rotavirus genes coding for a major capsid protein into the baculovirus expression system and expressed each protein in insect cells. Coexpression of different combinations of the rotavirus major structural proteins resulted in the formation of stable virus-like particles (VLPs). The coexpression of VP2 and VP6 alone or with VP4 resulted in the production of VP2/6 or VP2/4/6 VLPs, which were similar to double-layered rotavirus particles. Coexpression of VP2, VP6, and VP7, with or without VP4, produced triple-layered VP2/6/7 or VP2/4/6/7 VLPs, which were similar to native infectious rotavirus particles. The VLPs maintained the structural and functional characteristics of native particles, as determined by electron microscopic examination of the particles, the presence of nonneutralizing and neutralizing epitopes on VP4 and VP7, and hemagglutination activity of the VP2/4/6/7 VLPs. The production of VP2/4/6 particles indicated that VP4 interacts with VP6. Cell binding assays performed with each of the VLPs indicated that VP4 is the viral attachment protein. Chimeric particles containing VP7 from two different G serotypes also were obtained. The ability to express individual proteins or to coexpress different subsets of proteins provides a system with which to examine the interactions of the rotavirus structural proteins, the role of individual proteins in virus morphogenesis, and the feasibility of a subunit vaccine.

Animals↗
PubMed1994

[The effects of fibronectin on DNA synthesis and ultrastructure of periodontal ligament cells]

Microspectrophotometer and transmitted electron microscope (TEM) were used to study the change of DNA synthesis and ultrastructure after fibronection(FN) acted on cultured periodontal ligament cells (PDLC).The results showed that the data of nuclus area,nuclus total absorbs and nuclus mean absorbs of PDLC in FN group was higher than control(P<0.01).Under the TEM we observed that in FN group there were more euchromatin in cell nuclues and more organ cells such as microfilaments,chondriosomes and endoplasmic reticulum in cytoplasm.It suggested that FN can accelerate periodontal regeneration by promoting DNA and protein synthesis of PDLC.

Journal Article↗
PubMed1994

[The clinical significance of detection of anti-PPD-IgG secreting cell, adenosine deaminase and anti-PPD-IgG antibody in pleural effusion].

Enzyme-Linked Immunospot Assay (ELISPOT) were designed in the diagnostic value of tuberculous pleurisy, had a sensitivity of 90% and specificity of 100%. Anti-PPD IgG antibodies detected by ELISA had a sensitivity of 45% and specificity of 86%. For ADA activity in pleural effesion, the sensitivity and specificity were 75%, 79% respectively. Comparing with ADA and ELISA methods, ELISPOT is a more useful method for diagnosis of tuberculosis pleurisy.

Adenosine Deaminase↗
PubMed1993

[The relationship between periodontal diseases and prostacyclin in saliva of periodontal patients by RIA]

The purpose of this investigation was to measure the changes of Prostacyclin(PG12) occuring in gingivitis and periodontitis.Fifteen cases of periodontitis,ten cases of gingivitis and ten cases of healthy participated in this study,Saliva was taken before treatment,Prostacyclin in saliva was measure by radioimmunoassay(RIA).The results showed that prostacyclin of human saliva is increased from healthy gingivitis to periodontitis.There is a statistical difference between groups,6-k-PGF1alpha in saliva of periodontitis is 3.6 folds of healthy.Gingivitis is 2.6 folds of healthy.There is also a significant difference between adult periodontitis our findings suggested that prostacyclin may play an important role in etiology of periodontal disease.Measured 6-k-PGF1alpha in saliva may indicate the severity of periodontal disease.

Journal Article↗
PubMed1992

[Changes in serum folic acid and vitamin B12 levels in liver cirrhosis and its clinical significance].

The levels of serum folic acid and vitamin B12 were determined in 40 cases of liver cirrhosis with radioimmunoassay. It was shown that in 87.5% of the patients folic acid level was lower than that of a control group and in 67.5% serum vitamin B12 level was higher than that of the control group (P less than 0.05). The correlation between liver cirrhosis and dysbolism of folic acid and vitamin B12 and the megaloblastic changes and clinical significance were discussed.

Adult↗
PubMed1991

Concentration and detection of hepatitis A virus and rotavirus from shellfish by hybridization tests.

A modified polyethylene glycol precipitation method for concentration of virus followed by a new method to recover nucleic acid was used to detect hepatitis A virus (HAV) and rotavirus (SA11) in shellfish (oysters and hard-shell clams) by hybridization tests. Infectious virus, seeded into relatively large quantities of shellfish, was recovered consistently, with greater than 90% efficiency as measured by either in situ hybridization (HAV) or plaque assay (rotavirus SA11). Viral nucleic acid for dot blot hybridization assays was extracted and purified from virus-containing polyethylene glycol concentrates. Separation of shellfish polysaccharides from nucleic acid was necessary before viral RNA could be detected by dot blot hybridization. Removal of shellfish polysaccharides was accomplished by using the cationic detergent cetyltrimethylammonium bromide (CTAB). Use of CTAB reduced background interference with hybridization signals, which resulted in increased hybridization test sensitivity. After polysaccharide removal, dot blot hybridization assays could detect approximately 10(6) physical particles (corresponding to approximately 10(3) infectious particles) of HAV and 10(4) PFU of SA11 rotavirus present in 20-g samples of oyster and clam meats. These studies show continuing promise for the development of uniform methods to directly detect human viral pathogens in different types of shellfish. However, practical applications of such methods to detect noncultivatable human viral pathogens of public health interest will require additional improvements in test sensitivity.

Animals↗
PubMed1991

[Study on T-lymphocyte culture and function of T-lymphocyte subsets in patients with aplastic anemia].

T-lymphocytes form the peripheral blood of 12 patients with aplastic anemia (AA) and 4 patients with aplastic anaemia-paroxysmal hemoglobinuria syndrome (AA-PNH) were cultivated and their subsets were measured by monoclonal antibodies CD4, CD8, CD25 with indirect immunofluorescence technique. Change of the proportion of T-lymphocyte subsets was observed in 5 patients with AA after the mononuclear cells were activated with phytohemagglutinin (PHA). Its was shown that the number of CFU-T of the patients with AA was apparently decreased in comparison with that of normal controls (P less than 0.05). Disorder of T-lymphocyte subsets took place in patients with AA. The percentages of CD8 and CD25 lymphocytes were increased. The helper: suppressor T-lymphocytes (CD4:CD8) ratio was significantly increased (P less than 0.01). In the cases of AA-PNH, the number of CFU-T was significantly increased (P less than 0.01) and that of T-lymphocyte subsets did not change. The ratio of CD4/CD8 in 5 patients with AA was further decreased after activating mononuclear cells with PHA. These results showed that the increase of T-lymphocytes in patients with AA may account for the low level of CFU-T; the high level of CFU-T in patients with AA-PNH may be related to the multiplication of bone marrow cells. However, there may be a potential disorder of immune system on patients with AA at the same time.

Adolescent↗
PubMed1990

The effect of carbamylcholine on CFU-s differentiation.

The proportion of spleen colony-forming units (CFU-s) killed by hydroxyurea was greatly increased after bone marrow cells (BMCs) from LACA mice were exposed to carbamylcholine (Cach; 1 X 10(-13) to 1 X 10(-9) in vitro and there was a marked change in the proportion of spleen colony types. Following treatment with Cach, granulocytic and mixed erythroid-type colonies increased from 20 to 26.3% and 16.1 to 29.6% in 9-day colonies and from 8.3 to 28.2% and 21.7 to 39.4% in 13-day colonies, respectively. Single cell suspensions of spleen colonies were made for granulocyte-macrophage progenitor (CFU-gm) and late erythroid progenitor (CFU-e) assays. The number of CFU-gm from Cach-treated BMC was about twice that from control BMC for both day 9 and day 13 groups; the number of CFU-e decreased relatively. The results suggest that cholinergic receptors on CFU-s may increase the tendency to differentiate into the granulocytic/monocytic line.

Animals↗
PubMed1989

[Effects of carbamylcholine and impromidine on cell cycle state of CFU-S].

In normal steady-state conditions, there was less than 10% loss of CFU-S due to hydroxyurea (HU, 10(-3) mol/L). The CFU-S killed by HU was greatly increased after bone marrow cells of LACA mice were exposed in vitro to carbamylcholine (Cach) (10(-13)-10(-9) mol/L) and impromidine (Impro) (10(-9)-10(-4) mol/L). They were 32.8 (Cach) and 38.4% (Impro) for day 9 CFU-S; 60.6 (Cach) and 49.5% (Impro) for day 13 CFU-S at plateau phase. The effects were blocked by antagonists of cholinergic N receptor d-tubocurarine and of histamine H2 receptor cimetidine, respectively. The different sensitivity to agonists between CFU-S forming early spleen colonies and late colonies may reflect differences in receptor density on the surface of haemopoietic stem cells or receptor activity. The studies provide additional evidence suggesting the heterogeneity of pluripotent haemopoietic stem cells.

Animals↗
PubMed1989

[Effects of histamine H2-receptor antagonists on hemopoietic reconstruction in bone marrow].

The effects of histamine H2-receptor antagonists (cimetidine and ranitidine) on bone marrow hematopoiesis of normal and sublethally irradiated mice were investigated. It was found that non-toxic dosage of cimetidine had no significant effect on CFU-s of the normal mouse, but it inhibited CFU-GM growth with a dosage-dependent relationship and the recovery of CFU-s formation from sublethal gamma-ray irradiation. These results suggest that histamine may play a role in bone marrow regeneration after sublethal irradiation. Histamine H2-receptor antagonists can inhibit hemopoietic reconstruction in regenerating bone marrow.

Animals↗
PubMed1987

Prediction of aphakic refractive error in children.

Formulas created to predict the optical requirements of the aphakic eye have been tested mainly in adult eyes. The accuracy of these formulas in shorter pediatric aphakic eyes was examined using retrospective analysis of 17 aphakic pediatric patients. The Sanders-Retzlaff-Kraff contact lens formula, used previously to predict required lens powers for epikeratophakia, consistently underestimated the required aphakic correction in the shorter eyes, which may have been responsible in part for the large undercorrections obtained previously in patients under one year of age. The Hoffer-Colenbrander and Binkhorst theoretical formulas, Donzis-Kastl-Gordon percentage change formula, and a linear regression formula derived from the present data (LIN), were significantly more accurate. The differences between these formulas were not significant. The use of one of these formulas should facilitate prediction of required epikeratophakia lenticule power or intraocular lens power in young children.

Aphakia, Postcataract↗