Preparation of sodium fluoride-loaded gelatin microspheres, characterization and cariostatic studies

Sodium fluoride-loaded gelatin microspheres (NaF-GMS) were prepared using double-phase emulsified condensation polymerization. The average diameter of microspheres was (11.33+/-5.56) microm. The drug content and encapsulation efficiency were 8.80% and 76.73%, respectively. The fluoride releasing profiles of NaF-GMS in physiological saline and artificial saliva (pH 4.5, pH 6.8) showed that NaF-GMS had a sustained-release property and fluoride release rate was increased in pH 4.5 artificial saliva. Experiments conducted in rabbits' oral cavity using NaF-GMS and NaF solution as control revealed NaF-GMS could maintain oral fluoride retention longer than NaF solution. Cariostatic abilities of NaF-GMS including demineralization prohibition in vitro, fluoride deposition in artificial dental plaque and the ability of targeting to cariogenic bacteria were investigated in artificial dental plaque. The results indicated NaF-GMS with lower fluoride concentrations could achieve equivalent cariostatic effect to the concentrated NaF solution, at the same time, could prolong fluoride retention in dental plaque. Microscopic observation showed that NaF-GMS carrying fusion protein of glucan-binding domain could adhere more bacteria than NaF-GMS and this might indicate the possibility of targeting to cariogenic bacteria when NaF-GMS were properly modified.

[Construction and characterization of normalized cDNA library of maize inbred Mo17 from multiple tissues and developmental stages]

Comprehensive complementary DNA (cDNA) library is a valuable resource for functional genomics. In this study, we set up a normalized cDNA library of Mo17 (MONL) by saturation hybridization with genomic DNA, which contained expressed genes of eight tissues and organs from inbred Mo17 of maize (Zea mays L.). In this library, the insert sizes range from 0.4 kb to 4 kb and the average size is 1.18 kb. 10.830 clones were spotted on nylon membrane to make a cDNA microarray. Randomly picked 300 clones from the cDNA library were sequenced. The cDNA microarry was hybridized with pooled tissue mRNA probes or housekeeping gene cDNA probes. The results showed the normalized cDNA library comprehensively includes tissue-specific genes in which 71% are unique ESTs (expressed sequence tags) based on the 300 sequences analyzed. Using BLAST program to compare the sequences against online nucleotide databases, 88% sequences were found in ZmDB or NCBI, and 12% sequences were not found in existing nucleotide databases. More than 73% sequences are of unknown function. The library could be extensively used in developing DNA markers, sequencing ESTs, mining new genes, identifying positional cloning and candidate gene, and developing microarrays in maize genomics research.

Phytochemical and antiinflammatory studies on Terminalia catappa

The antiinflammatory activity of Terminalia catappa leaves ethanolic extract was studied using 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced ear edema in acute and chronic models. A bioassay-oriented fractionation procedure showed that the activity concentrates in the chloroform fraction. Ursolic acid (1) and 2alpha,3beta,23-trihydroxyurs-12-en-28-oic acid (2), isolated from the chloroform fraction, exhibited strong antiinflammatory activities. The results suggest that the triterpenic acids 1 and 2 are responsible for the antiinflammatory activity of T. catappa leaves.

[Gene point mutation in the dihydrofolate reductase-thymidylate synthase gene of Plasmodium falciparum]

OBJECTIVE

To investigate the gene point mutation in the dihydrofolate reductase-thymidylate synthase(dhfr) gene of Plasmodium falciparum isolate from Yunnan Province strongly associated with pyrimethamine and cycloguanil resistance.

METHODS

Nested PCR and restriction endonuclease digestion were applied to detect the gene mutation using dried blood filter paper collected from the fields in Yunnan Province.

RESULTS

Different mutations were found in 4 amino acids at positions 16, 51, 108 and 164 of dhfr gene, particularly, Asn-108 and Ile-51, the mutation frequency being 94.1% and 90.1%, respectively. The frequency of the wild-type genotype (3D7-type) Ser-108 appeared lower (9.1%), while the frequency of the Ala-16 was high(61.8%); the mutation-type was very high, the ratio of HB3-type, 7G8-type/FCR3-type and Cambodian-type was 1:21:7.5.

CONCLUSION

The investigation first demonstrated that Plasmodium falciparum Yunnan isolate dihydrofolate reductase-thymidylate synthase gene (dhfr) at positions 16, 51, 108 and 164 exhibited different degrees of point mutation. The frequency of mutation of the 7D8-type involved in pyrimethamine resistance was higher, while that of the FCR3-type involved in cycloquanil resistance was lower.

[Investigation on genotype constitution of different Plasmodium vivax isolates and its geographical distribution in China]

OBJECTIVE

To investigate the population constitution and geographical distribution of Plasmodium vivax in China using molecular technique.

METHODS

Blood-spot filter paper samples with related epidemiological data were collected from vivax malaria patients living in malarious area of 10 provinces (autonomous region) in China. Semi-nested- or nested-allelic-specific PCR genotyping method was used to identify CSP genotypes, families and types of Plasmodium vivax of each isolate from these patients.

RESULTS

Of 384 field isolates of Plasmodium vivax, 258 temperate zone family strains were identified, including 14 allelic variant genotypes spreading among 10 sampling provinces; allelic variants sized less than 731 bp were only seen in 5 provinces in southern China; 79 tropical zone family strains including 5 genotypes were also distributed in 5 provinces of southern China south to 25 degrees N. lat; and 14 PV Type-2 strains including 2 genotypes were found in some areas of Hainan and Yunnan Provinces. In addition, 33 isolates from genotype-mixed infections were revealed.

CONCLUSION

At present, area north to 25 degrees N. lat. of the country is the sole area prevalent for Plasmodium vivax family strains of temperate zone; there is overlapping distribution of P. v. of temperate zone family and tropical zone family of this parasite in the southern China south to 25 degrees N. lat; where the most complex isolate constitution is in Yunnan and Hainan Provinces, and PV Type-2 strains have been found in some areas of the two provinces. Besides, there were 2 groups of genotype with distinct geographic distribution feature within the temperate zone family.

[Studies on identification of circumsporozoite protein genotyping of Plasmodium vivax]

OBJECTIVE

To develop a new method of genotyping circumsporozoite protein (CSP) gene for identification of field isolates of Plasmodium vivax.

METHODS

Improved Chelex-100 ion-exchange method was used to extract DNA from blood filter paper samples, nested PCR and allele-specific PCR techniques, agarose gel electrophoresis analysis and dot/southern blotting-probe hybridization were employed for amplification, resolution and identification of the diagnostic fragments.

RESULTS

Using the nest-allele-specific PCR assay reported here, small amounts of DNA extracted from a piece of blood filter paper sample were amplified which produced three different size ranges of diagnostic bands: 650-770 bp PV-species-specific band, 170-230 bp diagnostic band for temperate zone family and 588 bp band for PV type-2. The sizes and patterns of the bands produced by the reference strains were consistent with those of designed target sequences. Of 59 examined isolates from 6 provinces of China, 42 temperate zone family strains, 15 tropical zone family strains and two PV type-2 strains were identified.

CONCLUSION

1, Three genotype strains of P. vivax mentioned above could be identified by this method with only two rounds of PCR and without probe hybridization. 2, The preliminary results showed that PV type-1 including temperate zone family strains and tropical zone family strains as well as PV type-2 strains are present in China. In addition, another CSP genotype with both sequence characteristics of temperate zone and tropical zone family might also be present in China.

[Experimental observation on anaphylaxis induced by Echinococcus infection in Meriones unguiculatus]

OBJECTIVE

To observe the anaphylaxis induced by Echinococcus granulosus or E. multilocularis (E. g. and E. m.) infection in Meriones unguiculatus.

METHODS

56 and 48 gerbils were intraperitoneally inoculated with E. g. protoscoleces and E. m. tissue homogenate. After three months, the anaphylactic responses initiated by intraperitoneal challenge injection with E. g. cystic fluids or partially purified antigen or E. m. metacestode homogenate antigen were observed. IgE antibody and direct eosinophilic leukocyte count (DELC) were detected at pre-postchallenge.

RESULTS

The infection rates for E. g and E. m. in 56 and 48 gerbils were 89.3% and 97.9%, respectively. Among these groups, the lowest rate of anaphylaxis was 62.5%, the highest was 100%. The lowest rate of anaphylactic shock was 12.5%, and the highest 16.7%. After the gerbis were infected with E. g. and E. m., both IgE antibody and DELC increased gradually. At 60 min post challenge, IgE antibody level were significantly decreased, while DELC showed a sharp increase.

CONCLUSION

Anaphylaxis could be induced in gerbils by Echinococcus infection followed by a challenge injection. Different antigens lead to different and degrees among the anaphylactic responses in the gerbils, however, there were no significant differences between E. g. and E. m. infections in gerbils.

Characterization of ambient volatile organic compounds at a landfill site in Guangzhou, South China

Ambient air monitoring was conducted at Datianshan landfill, Guangzhou, South China in 1998 to investigate the seasonal and horizontal variations of trace volatile organic compounds (VOCs). Twelve sampling points over the Datianshan landfill were selected and samples were collected simultaneously using Carbontrap(TM) adsorption tubes. Thirty eight VOCs were detected in the winter, whereas 60 were detected in the summer. The VOC levels measured in summer were alkanes, 0.5-6.5 microg/m(3); aromatics, 2.3-1667 microg/m(3); chlorinated species, 0.2-31 microg/m(3); terpines, 0.1-34 microg/m(3); carbonyl species, 0.3-5.6 microg/m(3) and naphthalene and its derivatives, 0.4-27 microg/m(3). Compared to the summer samples the VOC levels in winter were much lower (mostly 1-2 orders of magnitude lower). The aromatics are dominant VOCs in landfill air both in winter and summer. High levels of alkylbenzene and terpines such as methyl-isopropylbenzene (max 1667 microg/m(3)) and limonene (max 162 microg/m(3)) cause undesirable odor. The similar correlation coefficients of BTEX in summer and winter suggest VOCs emissions were from landfill site sources. The variation of BTEX ratio at landfill site is different from that in the urban area of Guangzhou. It shows that the ambient VOCs at landfill site were different from the urban areas.

Congou tea drinking and oesophageal cancer in South China

The study from a large hospital-based case-control for 1248 cases with oesophageal cancer and the same number of controls in South China showed that Congou, a grade of Chinese black tea, may protect against cancers of the oesophagus and reduce the risk of a combination of alcohol drinking and smoking (especially smoking), regardless of temperature when drinking.

[Determination of volatile organic compounds in atmospheric environment]

It is well known that volatile organic compounds (VOCs) are the main photochemical pollutants and ozone precursors of the photochemical smog. Investigation of photochemical pollution in the ambient air must focus on VOCs, but the concentration of VOCs in ambient air is in a very low level (10(-9)-10(-12), volume fraction), so there are difficulties in the determination of VOCs. In this work, based on the TO14A and TO15 methods recommended by the Environmental Protection Agency of United States, an improved method for the determination of fifty-six VOCs, mainly O3 precursors, in atmospheric environment was developed. Operating conditions of VOCs preconcentrator, gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) were optimized. Air sample was first frozen by liquid nitrogen, and then H2O and CO2 were eliminated in the VOCs preconcentrator. The preconcentrated VOCs sample was injected to GC and detected by MS or hydrogen flame ionization detector (FID). The C2-C10 hydrocarbons were separated effectively in capillary columns under the high concentration of CO2. The detection limits were 0.1 microgram.m-3 and the relative standard deviations were in the range from 2.57% to 9.82%. This method has been used for the determination of VOCs in real samples. The results were satisfactory.

[An association analysis of apolipoprotein E genotypes with Alzheimer's disease in Chinese population]

OBJECTIVE

To analyse the association of apolipoprotein E genotypes with Alzheimer's disease in Chinese population.

METHODS

Using PCR and restriction enzyme digestion, we have analyzed ApoE allele frequency of Alzheimer's disease (AD) patients and healthy controls.

RESULTS

Among the 56 cases of AD, the frequency of ApoE epsilon 2, ApoE epsilon 3, ApoE epsilon 4 are 3 (2.7%), 84 (75.0%), 25 (22.3%) respectively, while in the 67 controls they are 9 (6.7%), 115 (85.8%), 10 (7.5%) respectively. The frequencies of the two groups have significant difference (P < 0.01) and the frequency of ApoE epsilon 4 allele is higher in AD than that in the health controls and the statistical treatment suggest that there is significant difference (chi 2 = 10.99, P < 0.01, OR = 3.59, 95% CI = 1.54-8.41). The frequency of the ApoE epsilon 3 is lower in AD than that in the health controls and the difference is also statistically significant(P < 0.05).

CONCLUSIONS

Our results are consistent with previous work in that proving the ApoE epsilon 4 allele is one of the risk factors of AD. The results also provide a support for the protection effect of ApoE epsilon 3 allele in developing AD.

[HPLC determination of oleanolic acid and llrolic acid in Chinese medicinal herbs]

OBJECTIVE

To develop a new method for simultaneous determination of oleanolic acid and llrolic acid in Chinese medicinal herbs at the same time.

METHOD

HPLC was carried out on a Shim-pack CLC-ODS column using MeOH-H2O-HOAc-TEA (83:17:0.04:0.02).

RESULT AND CONCLUSION

The average recovery of oleanolic acid and llrolic acid was 103.3 +/- 2.07% and 102.7% +/- 0.65% respectively.

CD3+CD4-CD8- alphabeta-TCR+ T cell as immune regulatory cell

Down-regulation of immune responses by regulatory T cells is one of the major mechanisms involved in the induction of tolerance to self- and alloantigens as demonstrated in a number of models of transplantation and autoimmunity. It is clear that regulatory T cells consist of different subsets. Recently a novel subset of antigen-specific alphabeta-TCR+ CD4-CD8- (double negative, DN) regulatory T cells has been found to be able to inhibit the function of the CD8+ T cells carrying the same T cell receptor specificity and prevent the rejection of skin allografts. Identification of the DN regulatory T cells and their novel mechanism of suppression can help us to understand how donor-specific transplantation tolerance can be achieved and to explain how tolerance to self-antigens can be maintained in the periphery.

Construction, safety, and immunogenicity in nonhuman primates of a chimeric yellow fever-dengue virus tetravalent vaccine

We previously reported construction of a chimeric yellow fever-dengue type 2 virus (YF/DEN2) and determined its safety and protective efficacy in rhesus monkeys (F. Guirakhoo et al., J. Virol. 74:5477-5485, 2000). In this paper, we describe construction of three additional YF/DEN chimeras using premembrane (prM) and envelope (E) genes of wild-type (WT) clinical isolates: DEN1 (strain PUO359, isolated in 1980 in Thailand), DEN3 (strain PaH881/88, isolated in 1988 in Thailand), and DEN4 (strain 1228, isolated in 1978 in Indonesia). These chimeric viruses (YF/DEN1, YF/DEN3, and YF/DEN4) replicated to ~7.5 log(10) PFU/ml in Vero cells, were not neurovirulent in 3- to 4-week-old ICR mice inoculated by the intracerebral route, and were immunogenic in monkeys. All rhesus monkeys inoculated subcutaneously with one dose of these chimeric viruses (as monovalent or tetravalent formulation) developed viremia with magnitudes similar to that of the YF 17D vaccine strain (YF-VAX) but significantly lower than those of their parent WT viruses. Eight of nine monkeys inoculated with monovalent YF/DEN1 -3, or -4 vaccine and six of six monkeys inoculated with tetravalent YF/DEN1-4 vaccine seroconverted after a single dose. When monkeys were boosted with a tetravalent YF/DEN1-4 dose 6 months later, four of nine monkeys in the monovalent YF/DEN groups developed low levels of viremia, whereas no viremia was detected in any animals previously inoculated with either YF/DEN1-4 vaccine or WT DEN virus. An anamnestic response was observed in all monkeys after the second dose. No statistically significant difference in levels of neutralizing antibodies was observed between YF virus-immune and nonimmune monkeys which received the tetravalent YF/DEN1-4 vaccine or between tetravalent YF/DEN1-4-immune and nonimmune monkeys which received the YF-VAX. However, preimmune monkeys developed either no detectable viremia or a level of viremia lower than that in nonimmune controls. This is the first recombinant tetravalent dengue vaccine successfully evaluated in nonhuman primates.

Optical rubbery ormosils sensor for the detection of ammonia

Rubbery ormosil films with immobilized aminofluorescein (AF) were investigated to develop an optochemical sensor for the determination of ammonia in water. The gel precursors with tetramethoxysilane (TMOS) and dimethyldimethoxysilane (DiMeDMOS) were deposited on glass supports, and characterized in terms of response to pH, and to dissolved ammonia at constant pH. After preconditioning the sensing film was stable for 6 months. The detection limit for ammonia in water was 0.2 microg mL(-1) (S/N 2), the response being linearly dependent on concentration in the range of 0.5 to 80 microg mL(-1) ammonia. The response time was less than 5 min. The effects of sodium chloride concentration, temperature, and coexisting metal ions and compounds were investigated.

[Study on the phase II metabolites of phenoprolamine hydrochloride in rat bile by LC/DAD/MSD]

AIM

To study the phase II metabolites of phenoprolamine hydrochloride (DDPH) in rat bile.

METHODS

DDPH was administered by i.p. to bile duct-cannulated rats. Bile samples were collected before drug administration and up to 12 h after drug administration. After being purified and enriched with C-18 SPE columns the rat bile samples were analyzed by LC/DAD/MSD to identify the peaks of phase II metabolites. The fractions of phase II metabolites were prepared by HPLC and treated with beta-glucuronidase, and then were purified and enriched with C-18 SPE columns and analyzed by LC/DAD/MSD. The corresponding reference standards of DDPH phase I metabolites were analyzed by LC/DAD/MSD under identical conditions.

RESULTS

The peaks M7, M8 and M9 in the chromatograms of rat bile samples were the phase II metabolites of DDPH and the enzymatic hydrolysates of M7, M8 and M9 were 1-(2, 6-dimethyl-4-hydroxyphenoxy)-2-(3, 4-methoxyphenylethylamino)-propane (M3), 1-(2, 6-dimethyl-3-hydroxyphenoxy)-2-(3, 4-methoxyphenylethylamino)-propane (M2) and 1-(2,6-dimethylphenoxy)-2-(3-methoxy-4-hydroxyphenylethyl-amino)-propane (M1) respectively.

CONCLUSION

beta-1-O-[3,5-dimethyl-4-[-2-methyl-2-(3,4-dimethoxy-phenylethylamino)- ethoxy]-phenyl]-glucuronic acid (M7, glucuronide of M3), beta-1-O-[2, 4-dimethyl-3-[2-methyl-2-(3, 4-dimethoxy-phenylethylamino)-ethoxy]-phenyl]-glucuronic acid (M8, glucuronide of M2) and beta-1-O-[2-methoxy-4-[1-methyl-2-(2, 6-dimethylphenoxy)-ethylamino-ethyl]-phenyl]-glucuronic acid (M9, glucuronide of M1) were the phase II metabolites of DDPH in rat bile.

[Glutamate causes release of nitric oxide from chicken spinal cord in vitro]

Nitric oxide (NO) has been identified to have profound effects on many systems, especially the neural tissues. Many studies suggest that NO mediate the neurotoxicity of glutamate (Glu). In order to determine in vitro whether Glu causes release of NO from chicken spinal cord, different concentrations of Glu (0.1, 0.5, 1.0 mmol.L-1) were added to the primary cultured chicken spinal cord cells, and the quantity of NO- (the metabolism product of NO) in medium was detected. The result shows that Glu can enhance obviously the concentration of NO in primary cell cultures (212% compared with the control). If the spinal cord cells were pretreated with NO synthases (NOS) inhibitor--L-NOARG, the [NO-] was decreased compared with those treated with Glu only, and, on the contrary, the viability of cells was increased. All of the results above indicate that NO may play an important role in the neurotoxicity of Glu on nervous cells. It might be that Glu can instigate the activity of NO synthases, then induce a series of changes within cell and finally lead to the toxic effect on cells.

[Effect of combination of ligustrazine and nitrendipine on hemodynamics in patients with chronic obstructive pulmonary disease]

OBJECTIVE

To find the drugs for lowering the pulmonary vascular resistance in patients of chronic obstructive pulmonary disease (COPD) but would not increase its side-effect.

METHODS

Changes of some hemodynamic parameters in 15 patients of COPD in stable stage treated by nitrendipine and ligustrazine were observed by right heart floating catheterization.

RESULTS

The mean pulmonary arterial pressure reduced by 1.4% immediately after the combined treatment, and reduced by 17.0%, 20.0% and 18.0% in 15 mins, 30 mins and 60 mins after treatment. In the responding time, the pulmonary vascular resistance reduced by 15.2%, 36.2%, 43.0% and 34.6%, the systemic vascular resistance reduced by 7.9%, 19.2%, 17.9% and 20.8%, and the cardiac output increased by 15.8%, 22.6%, 22.2%, and 33.8% respectively. The changes of systemic arterial pressure and heart rate were of no statistical significance.

CONCLUSION

Combination therapy of nitrendipine and ligustrazine could lower the pulmonary arterial pressure and pulmonary vascular resistance effectively and has a selective effect on pulmonary circulation in patients with COPD.

[Study on the phase I metabolites of phenoprolamine hydrochloride in rat bile by LC/DAD/MSD]

AIM

To study the phase I metabolites of phenoprolamine hydrochloride (DDPH) in rat bile.

METHODS

DDPH was administered i.p. to bile duct-cannulated rats. Bile samples were collected before administration and up to 12 h after administration. After being treated with beta-glucuronidase, the bile samples were purified and enriched with C-18 SPE columns, and then were analyzed by LC/DAD/MSD. The samples containing synthesized reference standards of DDPH metabolite 1-(2, 6-dimethylphenoxy)-2-(3-methoxy-4-hydroxyphenylethylamino)-propane (M1), 1-(2, 6-dimethyl-3-hydroxyphenoxy)-2-(3, 4-methoxy-phenylethylamino)-propane (M2), 1-(2,6-dimethyl-4-hydroxyphenoxy)-2-(3,4- methoxyphenylethylamino)-propane (M3), 1-(2, 6-dimethyl-3-hydroxyphenoxy)-2-(3-hydroxy-4- methoxyphenylethylamino)-propane (M4), 1-(2, 6-dimethyl-3-hydroxyphenoxy)-2- (3-hydroxy-4-methoxyphenylethylamino)-propane (M5) and 1-(2,6-dimethyl-4-hydroxyphenoxy)-2-(3-methoxy-4- hydroxyphenylethylamino)-propane (M6) were analyzed by LC/DAD/MSD under identical conditions.

RESULTS

The retention times, UV spectra, molecular weights and production spectra (obtained by collision-induced dissociation) of the apparent ions of peak A, B, C, D, E and F in the total ion chromatogram of DDPH treated rat bile sample were consistent with those of M1, M2, M3, M5, M4 and M6, respectively.

CONCLUSION

M1, M2, M3, M4, M5 and M6 were identified as the phase I metabolites of DDPH in the rat.