Construction and in vitro expression of Streptococcus mutans surface protein encoding DNA vaccine

DNA vaccine plasmids were constructed that encoded two highly-conservative regions of a surface protein, PAc, from the human major cariogenic bacterium, Streptococcus mutans. Antigen expression was evaluated in vitro by immunohistochemical analysis of human endothelial cells following cationic liposome-mediated transient transfection with recombinant plasmid. The results of this study provided a basis for further testing of these recombinant plasmids in primates and for efficacy testing of dental caries DNA vaccines in human volunteers in future.

Caries patterns and their relationship to infant feeding and socio-economic status in 2-4-year-old Chinese children

AIMS

To describe the prevalence, severity and patterns of caries in 2-4-year-old children and to evaluate the association between caries experience of the children and their feeding patterns and socio-economic background in terms of mothers' education and family income.

DESIGN

Cross-sectional survey.

SETTING

Suburban area of Hanchuan in Hubei province, China.

PARTICIPANTS

A sample of 426 children (250 boys and 176 girls).

METHODS

Dental-examinations were undertaken in kindergartens using World Health Organization diagnostic criteria for dental caries. Mothers completed a short questionnaire.

OUTCOME MEASURES

Prevalence of caries; rampant caries; caries in incisors; caries in incisors and/or canines and molars; mean number of decayed, missing and filled teeth/surfaces (dmft/s).

RESULTS

36% of the children had caries, 7% had rampant caries. The more extensive pattern of caries involving primary molars as well as incisors and/or canines was seen in 12% of children. Children who had been wholly bottle-fed had five times the risk of having rampant caries compared to children who were breast-fed.

CONCLUSIONS

The results indicated that infant feeding practice might be a key risk factor for the development of caries at an early age in this country as elsewhere.

Immunolocalization of heat shock protein 70 during reparative dentinogenesis

OBJECTIVE

To investigate the immunolocalization of heat shock protein 70 (hsp 70) during reparative formation and to discuss the role of heat shock response in dental pulp injury and repair.

METHODS

A single cavity was prepared in the mesial surface of the first molars of both maxilla and mandible in Wistar rat. The animals were sacrificed at 3, 15, and 30 days post-operation. After the histological process, the paraffin sections were reacted with monoclonal antibodies against rat hsp 70 using the strept-avidin-biotin-peroxidase complex method.

RESULTS

Immunolocalization demonstrated heavy staining for hsp 70 in normal pulp and at different stages of dental pulp repair. In normal pulp, immunoreactivity was visualized in the odontoblasts and the pulp fibroblast. In the group sacrificed at 3 days, heavy staining was located in the odontoblast process and cytoplasm. After 15 days, the newly formed odontoblast-like cells were strongly stained. At 30 days, the same staining intensity was observed in odontoblast-like cells and in pulp cells. No staining was seen in reparative dentin.

CONCLUSION

These results demonstrated that heat shock protein 70 might play an important role as a molecular chaperone during reparative dentin formation.

Antigenic variation and cytoadherence of PfEMP1 of Plasmodium falciparum-infected erythrocyte from malaria patients

OBJECTIVE

To approve a theoretical basis for the molecular pathogenesis of human cerebral malaria and treatment with prevention.

METHODS

The blood samples were collected from 24 patients with cerebral malaria, 143 with falciparum malaria, 34 with vivax malaria and 20 healthy controls from the endemic areas of Yunnan Province, China. Using the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) technique, we determined the molecular mass (Mr) of these Plasmodium falciparum (P. falciparum) erythrocyte membrane protein 1 (PfEMP1) molecules.

RESULTS

Our findings indicate that higher molecular mass (260 kDa-320 kDa) forms of PfEMP1 were expressed on parasitized erythrocyte (PE) from human cerebral malaria patients. Compared with PfEMP1 expressed on PE from human cerebral malaria patients, the expression of PfEMP1 and Plasmodium vivax (P. vivax) erythrocyte membrane protein 1 (PvEMP1) on PE from falciparum malaria patients and vivax malaria patients did not have multiple bands of PfEMP1 of > or = 260 kDa, but had a PfEMP1 with molecular mass of 240 kDa and a PvEMP1 with molecular mass of 180 kDa band separately. Healthy controls expressed an EMP of molecular mass of 140 kDa.

CONCLUSION

Results confirm the antigenic variation of higher molecular mass of PfEMP1 whose molecular mass is equal to or exceeds 260 kDa-320 kDa on PE of patients with cerebral malaria. Our results show that the binding of large antigenic variability PfEMP1 molecular mass of 260 kDa-320 kDa on PE from human cerebral malaria patients with diverse receptor molecules on the endothelial cell (EC) of the cerebral microvessels may be involved in the molecular pathogenesis of cerebral malaria.

[The effect of immune bovine whey on cell-associated glucosyltransferase activity of Streptococcus mutans]

OBJECTIVE

To study the effect of immune bovine whey on cell-associated glucosyltransferase (GTF) activity of S. mutans MT8148.

METHODS

The immune milk was collected from cows immunized with cell-associated GTF overexpression strain B-29-33 of S. mutans MT8148. The control milk was from non-immunized cows. The immune absorbed whey was gotten from immune bovine whey which was absorbed with lyophilized Formalin-killed B-29 whole cells. Three kinds of whey were subdivided into three groups: 50 microliters, 70 microliters, 90 microliters. The content of insoluble glucan was estimated colorimetrically by anthrone method.

RESULTS

The control bovine whey had an enhancing GTF activity (407.00%-485.62%). The immune absorbed whey inhibited partly the enhancing GTF activity (208.74%-273.00%). The immune whey inhibited significantly the GTF activity (70.24%-38.62%) and the inhibition showed a tendency to depend on doses.

CONCLUSIONS

The immune bovine whey inhibits significantly the cell-associated GTF activity of S. mutans MT8148.

Oral health services in PR China as evaluated by dentists and patients

OBJECTIVE

To describe the function of oral health services and the delivery of oral health care in PR China.

DESIGN

Cross-sectional surveys. Self-administered questionnaires gathered information on professional practices and attitudes of Chinese dentists. Patients were examined clinically for caries and services rendered. Patients were interviewed about oral health status, reason of dental visits and consumption of services, perceived need for care and self-care practices.

SETTING

Wuhan City of the Hubei Province of China.

SUBJECTS

Random samples of dentists (n = 250) working with child and adult patients in 1998 in Wuhan City. Each dentist had a representative sample of 20 patients attending consecutively for care enrolled in the study.

RESULTS

On average, the dentists saw 12 patients per day, with most time devoted to restorative treatment and extraction. The majority of dentists held the opinion that in China little attention is given to preventive care. Forty per cent of the patients were new to the dentists and more than half attended care because of pain or acute symptoms. The reported mean number of decayed, missing, and filled teeth varied from 2.6 for 12-year-old patients to 10.7 for patients aged 65-74. Daily toothbrushing was practised by more than 90% of the patients in all age groups, however, the tradition of regular dental visits was weak. Most patients (51-75 per cent) attended for care due to acute problems or pain.

CONCLUSION

The study indicated the need for reorientation of the Chinese oral health services towards prevention.

Immunohistochemistry of bone sialoprotein and osteopontin during reparative dentinogenesis in vivo

OBJECTIVE

To investigate the stage-specific and tissue expression of bone sialoprotein (BSP) and osteopontin (OPN) during reparative dentinogenesis in vivo.

METHODS

Direct pulp-capping with Ca(OH)2 developed a model used for the investigation of reparative dentinogenesis in the exposed dental pulp. In this model, standardized class V cavities were prepared close to the gingival margin on the buccal surface of each tooth. Animals were sacrificed 3, 7, and 10 days post-operation. Immunohistochemical staining determined the tissue-specific expression of BSP and OPN during the process.

RESULTS

Odontoblast-like cells and reparative dentin reacted positively with BSP and OPN. The expression of BSP reached a peak at day 7, then gradually decreased, while the expression of OPN showed no significant difference between day 7 and day 10.

CONCLUSION

BSP and OPN may play different roles in reparative dentinogenesis. BSP may serve as a nucleator of hydroxyapatite crystal formation.

In situ hybridization analysis of transforming growth factor-beta 1 RNA expression during mouse tooth development

OBJECTIVE

The aim of this study is to investigate the temporal and spatial expression and localization of transforming growth factor-beta 1 mRNA during mouse tooth development.

METHODS

The distribution pattern of TGF-beta 1 mRNA during tooth development was analyzed on 5 microns serial sections of paraformaldehyde-fixed and paraffin-embedded embryonic mouse heads or mandibles.

RESULTS

The results show that TGF-beta 1 mRNA is expressed during mouse tooth development in a temporally and spatially regulated fashion. Local expression of TGF-beta 1 mRNA in the dental epithelium at budstaged (E13) and capstaged (E15) teeth were observed. During bell stage (E16-18), TGF beta 1 mRNA was very abundant in the ameloblast layer and dental papilla cells. The expression of TGF-beta 1 increased in the layer of odontoblast and ameloblast with the differentiation of these cells.

CONCLUSION

These results suggest that TGF-beta 1 may have an important role in odontogenesis and that it acts as a paracrine and autoinducing factor.

Expression of and cytokine activation by Escherichia coli curli fibers in human sepsis

Curli organelles are expressed by commensal Escherichia coli K12 and by Salmonella typhimurium at temperatures <37 degrees C, which bind serum proteins and activate the contact-phase system in vitro. This study demonstrates, by means of an anti-CsgA (curli major subunit) antibody, that a significant fraction of E. coli isolates (24 of 46) from human blood cultures produce curli at 37 degrees C in vitro. Serum samples from 12 convalescent patients with sepsis, but not serum from healthy controls, contained antibodies against CsgA (n=12). This study further demonstrates that a curli-expressing E. coli strain and a noncurliated mutant secreting soluble CsgA induce significantly (P<.05) higher levels of proinflammatory cytokines (tumor necrosis factor-alpha, interleukin [IL]-6, and IL-8) in human macrophages differentiated from THP-1 cells. These data, therefore, provide direct evidence that curli are expressed in vivo in human sepsis and suggest a possible role for curli and CsgA in the induction of proinflammatory cytokines during E. coli sepsis.

[Effects of monoclonal antibody against the major cell surface protein on salivary agglutinin mediated aggregation of Streptococcus sobrinus]

OBJECTIVE

To investigate the effects of monoclonal antibody on salivary agglutinin-mediated aggregation of Streptococcus sobrinus in vitro.

METHODS

Bacterial aggregation inhibition was measured under OD650 at 10 minutes intervals for 1 hour.

RESULTS

It showed that the McAb ZS2/286 raised against the PAg of S. sobrinus 6715 could inhibit the aggregation by some degree, but the effect was not significant.

CONCLUSION

The McAb ZS2/286 might not bind directly to the functionally important region of PAg related to aggregation.

Immunolabeling of the major cell surface protein antigen of Streptococcus sobrinus with monoclonal antibody

OBJECTIVE

The purpose of this study was to determine the accessibility of monoclonal antibody (McAb), specific for the major cell surface protein antigen (PAg) of Streptococcus sobrinus, to the surface of its native epitopes.

MATERIALS AND METHODS

An indirect immunogold labeling technique was used to detect the reaction of McAb with S. sobrinus 6715. The reactions of polyclonal antibodies (PcAbs) against S. sobrinus 6715 or PAg with S. sobrinus 6715, S. mutans Ingbritt C and S. rattus BHT were studied as controls.

RESULTS

The results indicated that PAg was localized on the outer cell surface of S. sobrinus, and McAb was reactive with only a few epitopes of the cell surface, whereas PcAbs were found to be reactive with more epitopes.

CONCLUSIONS

McAb was specific for the PAg, but there was cross-reaction with S. mutans. Also there seemed to be an association between the fuzzy coat on the surface of S. sobrinus and PAg.

[Effect of monoclonal antibody on the colonization of Streptococcus sobrinus and the development of dental caries in rats]

OBJECTIVE

To investigate the effect of local application of monoclonal antibody (McAb) raised against the major cell surface protein antigen of streptococcus sobrinus (PAg) on the colonization of rats' teeth by Streptococcus sobrinus (S. sobrinus) and the development of dental caries.

METHODS

30 wistar rats were divided into three groups: group I received McAb against PAg; group II received unrelated mice ascites; group III received PBS. They were applied on six occasions. After three times of application, streptomycin resistant S. sobrinus 6715 were inoculated onto the teeth and the rats were fed with caries-inducing diet 2000#. The number of colonized S. sobrinus were counted and the presence of caries was examined by the procedure of Keyes'.

RESULTS

There was a significant lower level of colonization by S. sobrinus and lower mean caries scores treated with McAb compared with the control groups.

CONCLUSION

Local passive immunization with McAb against PAg may be an effective way to prevent the colonization by implanted S. sobrinus and the development of dental caries.

[The design of an ultrasonics Doppler spectrum analysis system for fetal umbilical blood flow monitoring]

This paper explains the design of an Ultrasonics Doppler Spectrum Analysis System for fetal umbilical blood flow monitoring. The gist of discussion includes the sampling method of the Doppler signals and the algorithm of the blood flow parameters. Because the DSP chip is not used in the AD cardboard, the hardware design is simplified and the system works steadily. In the process of computing the blood flow paramenters, an autochange method of the amplitude threshold and a timeout control technology are used, so the algorithm has good adaptability and works very stable.

Effects of monoclonal antibody on colonization of Streptococcus sobrinus and development of dental caries in rats

OBJECTIVE

To investigate the effect of local application of monoclonal antibody (McAb) raised against the 210KD cell surface protein antigen (PAg) of Streptococcus sobrinus on the colonization of rats' teeth and the development of dental caries.

MATERIALS AND METHODS

Thirty Wistar rats were divided into 3 groups: group 1 received McAb against PAg; group 2 received unrelated mice ascites; group 3 received pure buffered saline. The bacteria were applied 6 times to the occlusal surfaces of molars and to the labial surfaces of incisors. After three applications, streptomycin-resistant S. sobrinus 6715 was applied to the teeth and the rats were fed with caries-inducing diet 2000. The number of colonized S. sobrinus was counted on the streptomycin-supplemented mutans streptocci agar and expressed as a percentage of the total colonies on BHI agar. The presence of caries was examined and scored following Keyes' procedure.

RESULTS

There were significantly lower levels of colonization by S. sobrinus on rats' teeth and lower mean caries scores on the teeth treated with McAb compared with those in the control groups.

CONCLUSION

Local passive immunization with McAb against PAg may be an effective way to prevent colonization by implanted S. sobrinus and development of dental caries.

[The effect of retinoic acid on crown morphogenesis of mouse tooth germs in vitro]

OBJECTIVE

To study the effects of retinoic acid on crown morphogenesis of early tooth germs.

METHODS

Mouse tooth organ culture model was used and the functions of different retinoic acid concentration on the first mandibular molar germs of 14-day old mouse embryo were examined.

RESULTS

The first mandibular molar germ of 14-day old mouse was at the bud stage. After 6 days culture, tooth germs in culture medium (not containing retinoic acid) developed from bud stage to bell stage and formed normal cusps. The morphogenesis of tooth germs in medium containing 1 x 10(-7) mol/L retinoic acid was similar to molar germs in the medium without retinoic acid. When the concentration of retinoic acid increased to 1 x 10(-6) mol/L, the mouse tooth germs still developed from bud stage to bell stage, but normal cusps was not formed.

CONCLUSION

The results suggest that high concentration of retinoic acid alter crown morphogenesis of tooth germs.

Immunohistochemistry and in situ hybridization investigation of transforming growth factor-beta: during odontoblast and ameloblast differentiation

OBJECTIVE

The purpose of this study was to investigate the expression of transforming growth factor-beta, TGF-beta 1 during odontoblast and ameloblast differentiation.

METHODS

The analysis was made on 5-micron serial sections of the glutaraldehyde-fixed and paraffin-embedded mandibular first and second molars of a neonatal mouse. A specific and affinity-purified antibody to TGF-beta 1 and a digoxigenin-labeled cRNA probe were used.

RESULTS

The results showed that the TGF-beta 1 was expressed in a spatial and temporal pattern in dental tissues. The immunoreactivity of dental tissues for TGF-beta 1 was consistent with the expression of TGF-beta 1 mRNA revealed by in situ hybridization before dentin matrix formation. The TGF-beta 1 was evenly expressed in dental papilla and inner enamel epithelium. The expression of TGF-beta 1 was increased in the layer of odontoblasts and ameloblasts and in the stratum intermedium with the formation of dentin matrix, where the staining was also observed.

CONCLUSIONS

These findings suggest that TGF-beta 1 may have an important role in extracellular matrix formation and cytodifferentation.

[A study on anti-caries activity of genetic recombinant vaccine of Streptococcus lactis. II. Immunization in vein with recombinant S. lactis in pregnant rabbits]

The effects of immunization in vein with recombinant S. lactis HL107 carring the S. mutans surface protein PAc gene in pregnant rabbits were studied. The results indicated that specific anti-PAc IgG in serum and milk were obviously induced 1 week after immunization and retained at high level for several weeks. It suggests that the recombinant S. lactis HL107 possessing immunogenicity of S. mutans surface protein PAc is able to stimulate specific systemic immune response against PAc.

[The experimental study of immunization with purified surface protein antigen I/II from streptococcus mutans in BALB/c mice]

OBJECTIVE

To study the immunogenicity and immunoreactivity of purified surface protein antigen I/II from streptococcus mutans.

METHODS

Purified antigen I/II was used to immune BALB/c mice by subcutaneous injection route, and S. mutans whole cells were used as comparison.

RESULTS

ELISA showed immunization with antigen I/II highly induced both specific serum IgG antibody and specific salivary IgA antibody against antigen I/II (P < 0.01), but immunization with whole cells only induced specific serum IgG antibody (P < 0.05).

CONCLUSION

The study suggest purified antigen I/II is an effective candidate vaccine.

[Molecular cloning and sequencing of genes encoding MSP2 isolates strains from two of Plasmodium falciparum from Chinese patients with cerebral malaria]

OBJECTIVE

To provide the scientific evidence for designing safe and effective vaccines of human cerebral malaria.

METHODS

Genomic DNA samples of two isolated Plasmodium falciparum isolate strains prepared directly from 5 cases of cerebral malaria patients' blood in mengla County, Yunnan Province (CMH/YN) and in Yingjiang County, Yunnan Province (CYJ/YN) were used for polymerase chain reaction (PCR) amplification and the two pairs of oligonucleotides for the highly conserved genes encoding FC27 merozoite surface protein 2 (MSP2) of Papua New Guinea strain of Plasmodium falciparum were used as primers. The PCR products were digested with BamH1 and Hind III respectively, and the generated fragment MSP2 were cloned into M13mp18 and M13mp19 vectors and their DNA was analyzed as the templates for DNA sequencing by the dideoxy chain-termination method.

RESULTS

Compared with the published findings, FC27, K1, IC1 and CAMP sequences, DNA sequences of MSP2 from two isolated CMH/YN and CYJ/YN of Plasmodium falciparum strains from Chinese patients with cerebral malaria contained identical genes composed of 800 bp, encoding 264 amino acid, which were highly homologous up to 98.8% with that of FC27, K1 strain other than the IC1, CAMP strain.

CONCLUSION

It is the first record of DNA sequencing of MSP2 determined from two isolated CMH/YN and CYJ/YN of Plasmodium falciparum strains from Chinese patients with cerebral malaria, MSP2 mutation may be one factor leading to the localized cerebral damage which causes clinical coma of human cerebral malaria.

[The design of the ultrasonic Doppler spectrum analyze system for the naval blood stream of fetus]

The design of the Ultrasonic Doppler Specturm Analyze System for the naval blood stream of the fetus is discussed, mainly on the sampling method of the Doppler signals and the algorithm of the blood stream parameters. Because the DSP chip is not used in the AD cardboard, the hardware design is not only simplified, but also works more steady. In the process of the blood stream parameters, an autochange method of the amplitude threshold and a time-out control technology are used, so the algorithm has good adaptation and works very stable.

Curli fibers are highly conserved between Salmonella typhimurium and Escherichia coli with respect to operon structure and regulation

Mouse-virulent Salmonella typhimurium strains SR-11 and ATCC 14028-1s express curli fibers, thin aggregative fibers, at ambient temperature on plates as judged by Western blot analysis and electron microscopy. Concomitantly with curli expression, cells develop a rough and dry colony morphology and bind the dye Congo red (called the rdar morphotype). Cloning and characterization of the two divergently transcribed operons required for curli biogenesis, csgBA(C) and csgDEFG, from S. typhimurium SR-11 revealed the same gene order and flanking genes as in Escherichia coli. The divergence of the curli region between S. typhimurium and E. coli at the nucleotide level is above average (22.4%). However, a high level of conservation at the protein level, which ranged from 86% amino acid homology for the fiber subunit CsgA to 99% homology for the lipoprotein CsgG, implies functional constraints on the gene products. Consequently, S. typhimurium genes on low-copy-number plasmids were able to complement respective E. coli mutants, although not always to wild-type levels. rpoS and ompR are required for transcriptional activation of (at least) the csgD promoter. The high degree of conservation at the protein level and the identical regulation patterns in E. coli and S. typhimurium suggest similar roles of curli fibers in the same ecological niche in the two species.

[The design of a circuit for detecting respiration signal with impedance method]

A respiration signal detecting circuit with impedance method is introduced. In this circuit, a four electrode arrangement is used, which can reduce movement artifact in using two electrodes. In signal processing, a series of methods such as filtering and amplyfing are used to overcome the heart beat and bloodflow signals. The circuit has successfully been applied in the blocking physiological parameters monitor that we have developed.

Expression of thin aggregative fimbriae promotes interaction of Salmonella typhimurium SR-11 with mouse small intestinal epithelial cells

The factors that mediate binding of Salmonella typhimurium to small intestinal epithelial cells have not been fully characterized. In this paper we demonstrate that elimination of production of thin aggregative fiber by a transposon insertion within the gene encoding the subunit protein of the fiber reduced binding of S. typhimurium SR-11 to a conditionally immortalized proximal small intestinal epithelial cell line established from transgenic mice. This binding defect could be overcome by transcomplementation with a wild-type allele. The conditionally immortalized cell line should prove useful in identifying the epithelial cell receptor for bacterial attachment since expression of its bacterial binding activity can be induced by manipulating the line's proliferative status.

[Effects of sodium doecyl sulfate on the artificial dental plaque in chemostat]

Sodium doecyl sulfate (SDS) is widely used as a detergent in dentifrices. It has been shown to interfere with the protein adsorption to hydroxyapatite (HA), and inhibit acquired pellicle formation. The aim of the present study was to examine the effects of SDS on the artificial dental plaque in chemostat. The amount of the 3H-labelled bacteria adhered on the enamel fragment surface was determined with scintillometer. The artificial dental plaque was observed under the scanning electron microscope. The results showed that enamel fragments treated with SDS adsorbed less bacteria than untreated ones, and had no plague formed. It suggested that SDS can inhibit the bacterial adherence on enamel surface and thus reduce dental plaque formation.