A four-day study to evaluate the anti-plaque efficacy of an experimental triclosan-containing dentifrice

Four-day, non-brushing studies have been used successfully to demonstrate the anti-plaque efficacy of triclosan-containing dentifrices. The treatment effects observed are variable, likely due to differences in formulation, study design and measurement techniques. This randomized, double-blind crossover study was conducted to evaluate the anti-plaque efficacy of an experimental, multiple-benefit, triclosan-containing dentifrice versus two currently marketed sodium fluoride dentifrices in a four-day, lingual-brushing model on subjects in Beijing. People's Republic of China. Subjects brushed the lingual surfaces for 30 seconds, and before expectorating, swished the saliva/dentifrice slurry over the buccal surfaces for an additional 30 seconds. This procedure was repeated. Subjects performed their assigned brushing regimen twice daily for four days under supervision. On Day 5, plaque was measured using the Turesky Modification of the Quigley-Hein Plaque Index. There were highly significant treatment effects in favor of the experimental triclosan-containing dentifrice for whole mouth, buccal and lingual sites when compared to either of the sodium fluoride dentifrices (p < 0.0001).

Pyrogenic cytokines injected into the rat cerebral ventricle induce cyclooxygenase-2 in brain endothelial cells and also upregulate their receptors

Peripheral immunological insults induce interleukin (IL)-1 beta and IL-6 in the brain. To elucidate the mechanism(s) of fever evoked by these brain-derived cytokines, and possible interactions between them, we examined in rats: (i) whether cyclooxygenase-2 is responsible for fever evoked by central injection of these cytokines; (ii) if so, where in the brain cyclooxygenase-2 is induced; (iii) where the receptors for these cytokines are located; and (iv) how the expression of these receptors is influenced by the cytokines. Intracerebroventricular injection of these cytokines evoked fever that was suppressed by a cyclooxygenase-2 inhibitor. Brain endothelium was the site of cyclooxygenase-2 induction by these cytokines. IL-1 receptor (IL-1R) was constitutively expressed in brain endothelium, and its mRNA was further upregulated by either cytokine. IL-6R mRNA was constitutively expressed in the cerebral cortex, and was newly induced in as yet unidentified cells in brain blood vessels by either cytokine. Messenger RNAs for cyclooxygenase-2, IL-1R, and IL-6R were often observed in the same blood vessels. These results suggest that COX-2 induced in brain endothelium is, at least in part, involved in the fever evoked by these cytokines, and that one possible interaction between these two cytokines is mutual upregulation of their receptors in the endothelium or perivascular cells, resulting in augmentation of their actions.

Diagnosing primary and metastatic renal cell carcinoma: the use of the monoclonal antibody 'Renal Cell Carcinoma Marker'

The diagnosis of primary or metastatic renal cell carcinoma (RCC) can be difficult, especially in small biopsies, because of the wide variety of histologic appearances and clinical presentations that RCC can assume. An immunomarker specific for RCC is currently not available. We tested the relevant diagnostic use of the Renal Cell Carcinoma Marker (RCC Ma), a monoclonal antibody, against a normal human proximal tubular brush border antigen. Immunostaining using RCC Ma and the avidin-biotin-peroxidase complex technique was performed on archival tissues from primary and metastatic tumors of renal or nonrenal origin. A total of 122 of 153 primary RCCs (79.7%) were positive [clear cell (84%), papillary (96%), chromophobe (45%), sarcomatoid (25%), and collecting duct (0%)], with > or =10% of tumor cells stained in 93% of cases. None of the 64 primary renal tumors other than RCC, including 15 oncocytomas, was positive. Fifteen of 146 (10.2%) nonrenal primary tumors were positive (5 of 17 breast tumors, 8 of 8 parathyroid adenomas, and 2 of 7 embryonal carcinomas). Forty-two of 63 (67%) metastatic RCCs were positive with > or =10% of cells being stained in 83% of them. Two of 108 (2%) metastases from tumors other than RCCs were positive, both of which were metastatic breast carcinomas; however, only 10% (2 of 19) of metastatic breast carcinomas were positive. RCC Ma is an excellent marker for primary RCC, which should facilitate its diagnosis in a small biopsy. Although RCC Ma remains highly specific (98%) for metastatic RCC, a negative result may not rule out metastatic RCC because of a rather low sensitivity and a focal staining pattern in some of the positive cases. RCC Ma may also facilitate the differential diagnosis between oncocytoma and other types of RCC when they are composed mostly of eosinophilic cells.

[The efficacy of the chlorhexidine chip following scaling and root planing (SRP) and compared to SRP alone]

OBJECTIVE

To evaluate the clinical efficacy and safety of the adjunctive use of Chlorhexidine Chip (CHX; commercial name, Perio Chip) following scaling and root planing (SRP) in periodontitis.

METHODS

One center, blinded, randomized, split-mouth and active control study was designed. Sixty-five adult periodontitis patients were enrolled into the baseline after SRP. Each subject had at least one tooth with pocket depth of 5 mm or more and bleeding on probing (BOP) in each side of the mouth. Then the tooth was selected as a target and its parameters of probing depth (PD), attachment loss (AL), BOP, gingival index (GI), plaque index (PI) and staining index (SI) were recorded. Each side of mouth was randomly assigned to one of two treatments--drug placement after SRP or SRP alone. All the adverse events and parameters were recorded at time of 3-month, 6-month and meanwhile the patients received oral hygiene instruction and scaling. The same was conducted at 6-week, 4.5-month except for recording of parameters and scaling of the target teeth.

RESULTS

Reduction of PD and gain of attachment at 6-month in group of SRP plus CHX (1.32 mm, 0.94 mm) were significantly higher than those in group of SRP alone (0.77 mm, 0.40 mm) (P < 0.001). Forty-four point six percent (44.6%) of patients reflected adverse reactions related to drug placement. Toothaches, the main reactions, were mild to moderate in nature and spontaneously resolved within 2-4 days.

CONCLUSIONS

The chlorhexidine chip is indeed a safe and effective control-delivered drug for topical use when patient in his supportive periodontal therapy.

Duration and specificity of humoral immune responses in mice vaccinated with the Alzheimer's disease-associated beta-amyloid 1-42 peptide

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by overproduction of beta-amyloid (Abeta), which is formed from amyloid precursor protein (APP), with the subsequent pathologic deposition of Abeta in regions of the brain important for memory and cognition. Recently, vaccination of murine models of AD that exhibit Abeta deposition has halted or delayed the usual progression of the pathology of AD. Our group has demonstrated that vaccination of a doubly transgenic mouse model (expressing mutant APP and presenilin-1) with the Abeta 1-42 peptide protects these mice from the memory deficits they would ordinarily develop. This report further characterizes the Abeta 1-42 peptide vaccine in mice. Anti-Abeta response time course analysis indicated that at least three vaccinations (each 100 microg) were necessary to elicit a significant anti-Abeta titer. Subsequent vaccinations resulted in half-maximal antibody titers of at least 10,000, and these titers were maintained for at least 5 months after the final boost. Peptide binding competition studies indicated that the highest humoral responses are generated against the N terminus of the Abeta peptide. Also, measurement of specific murine Ig isotypes in Abeta-vaccinated mice demonstrated a predominant IgG(1) and IgG(2b) response, suggesting a type 2 (Th2) T-helper cell immune response, which drives humoral immunity. Finally, lymphocyte proliferation assay experiments using Abeta peptides and splenocytes from vaccinated mice demonstrated that the vaccine specifically stimulates T-cell epitopes present within the Abeta peptide.

Abnormal DNA-binding of transcription factors in minimal change nephrotic syndrome

The activation of transcription factors such as nuclear factor kappaB (NF-kappaB) and activator protein 1 (AP-1) plays an important role in regulating the expression of target genes, including those for cytokines involved in pathogenesis of minimal change nephrotic syndrome (MCNS). The therapeutic effects of glucocorticoids depend on the glucocorticoid receptor (GR) acting on gene transcription and interacting with certain transcription factors. To explore the role of transcription factors in the pathogenesis of MCNS and the therapeutic effects of glucocorticoids, we examined the DNA-binding abilities of NF-kappaB, AP-1, and GR in peripheral blood mononuclear cells (PBMC) from 6 children with MCNS and 6 healthy controls by electrophoretic mobility shift assay (EMSA). NF-kappaB and AP-1 DNA-binding abilities were significantly increased both at baseline and after stimulation by phorbol 12-myristate 13-acetate (TPA) in PBMC from MCNS patients compared with controls, but declined to normal levels after treatment with dexamethasone (DEX). GR DNA-binding abilities were significantly reduced at baseline and after treatment with TPA, but were enhanced markedly by DEX. There were strong correlations between urinary protein and the baseline DNA binding ability of NF-kappaB or AP-1, or GR. These results suggested that the abnormal activation of NF-kappaB and AP-1 and the reduction of GR DNA-binding abilities may be involved in the pathogenesis of MCNS. Inhibition of NF-kappaB and AP-1 and enhancement of GR DNA-binding abilities by DEX may form the molecular basis of the effects of glucocorticoids in MCNS.

Expression of Streptococcus mutans wall-associated protein A gene in Chinese hamster ovary cells: prospect for a dental caries DNA vaccine

The Streptococcus mutans strain GS-5 wall-associated protein A (Wap-A) is a precursor to the extracellular antigen A (AgA), a recognized candidate dental caries vaccine. The full-length wapA gene (wapA-E) and a C-terminal truncated version (wapA-G) encoding the AgA were cloned into the mammalian expression vector pcDNA 3.1/V5/His-TOPO. The resulting constructs were propagated in the Escherichia coli Top10. To investigate the expression of the S. mutans genes in mammalian cells, the above constructs were used to transfect Chinese hamster ovary (CHO) cells in the presence of the cationic lipid pfx-8. Transient expression of the wapA-E and wapA-G genes was observed at 24 h post-transfection, as shown by Western immunoblot analysis using a rabbit antiserum to S. mutans cell wall. Immunochemical staining of the transfected CHO cells showed expression of WapA mainly in the cells and budding vesicles, whereas AgA was found mainly in the transfected cells and extracellular medium. The expression of S. mutans proteins in CHO cells, in either vesicles or soluble form, suggested an antibody response to the above DNA constructs. Work is under way to test the efficacy of these as DNA vaccines against S. mutans.

[A study on affecting factors on dental care demands by logistic regression model]

OBJECTIVE

To develop probability model for dental visits based on analysis of the factors affecting people's dental services utilization in urban area of Beijing, thus providing some evidence for forecasting further demanded dental care and building the more efficient oral health care delivery system.

METHODS

A cross-sectional survey was conducted amnog 1,517 subjects of all age groups in Beijing selected by stratified, clustering, random sampling. The first model of dental care demand--probability model for dental visits was established with logistic regression.

RESULTS

Awareness of oral health showed the most important relationship. Different social background and economic factors also had great effects on demand. Higher demand for care were existed among those who suffered from a disease that was painful or resulted in poor oral function.

CONCLUSIONS

It is suggested that dental care has different characters from general health service. Utilization of dental service is largely determined by people's awareness, income and insurance system. So oral health education should be extended in order to promote the effective demands and reduce the potential demands. Rational oral health insurance system should be set up to provide some priority to certain people, thus stimulating the supply of dental care and improving the utilization of dental service. Since raising price for care will restrain the low-incomer's basic demand, and it will neither add the profit nor improve people's oral health, the price decision should be considered carefully. At last, oral health care should be emphasized on children and adolescent as priority age groups based on the conclusion from demand model.

Medial axis reformation: a new visualization method for CT angiography

RATIONALE AND OBJECTIVES

The authors performed this study to evaluate a new method (medial axis reformation [MAR]) for visualizing three-dimensional vascular data at electron-beam computed tomographic (CT) angiography.

MATERIALS AND METHODS

MAR was performed automatically with a personal computer-based workstation. After the region of interest was edited, voxels were divided into groups according to their path lengths. Centroids of groups were connected to form the medial axis. Then, the medial axis was refined with multiscale medial response. Bifurcations were also detected and refined. Finally, curved sections were generated through the branches and laid out onto a single image by using a splitting method. The authors performed MAR during electron-beam CT angiography of coronary arteries, common carotid arteries, and iliac arteries.

RESULTS

MAR displayed curved sections of branched vessels on one image, cut through the axis of vessels to show the vessel diameter objectively, and allowed the viewing direction to be altered arbitrarily.

CONCLUSION

Results of preliminary applications demonstrate that MAR is a valuable new visualization method for CT angiography.

Topological indices based on vertex, distance, and ring: on the boiling points of paraffins and cycloalkanes

Vertex, distance, and ring (in cyclic compounds) are three essential structure elements of a molecular graph, based on which three new topological indices VDI, OEI, and RDI are proposed. Multiple regression analysis was carried out against the boiling points of 343 hydrocarbons(160 paraffins and 183 cycloalkanes) with VDI, OEI, RDI, and N(2/3)(N is the number of carbon atoms) together, and a good QSPR model was obtained: ln(577 - Bp) = 6.729609 - 0.154107N(2/3) + 2.285632 x 10(-2)VDI - 7.921410 x 10(-3)OEI - 1.821962 x 10(-2)RDI (F = 6455.09, r = 0.9935, rms = 6.44 degrees C, n = 343).

Ethanol-induced swelling in neonatal rat primary astrocyte cultures

We tested the hypothesis that astrocytes swell in response to ethanol (EtOH) exposure. The experimental approach consisted of an electrical impedance method designed to measure cell volume. In chronic experiments, EtOH (100 mM) was added to the culture media for 1, 3, or 7 days. The cells were subsequently exposed for 15 min to isotonic buffer (122 mM NaCl) also containing 100 mM EtOH. Subsequently, the cells were washed and exposed to hypotonic buffer (112 mM NaCl) containing 100 mM mannitol. Chronic exposure to EtOH led to a marked increase in cell volume compared with control cells. Specific anion cotransport blockers, such as SITS, DIDS, furosemide, or bumetanide, when simultaneously added with EtOH to hyponatremic buffer, failed to reverse the EtOH-induced effect on swelling. In acute experiments, confluent neonatal rat primary astrocyte cultures were exposed to isotonic media (122 mM NaCl) for 15 min, followed by 45-min exposure to hypotonic media (112 mM NaCl, mimicking in vivo hyponatremic conditions associated with EtOH withdrawal) in the presence of 0-100 mM EtOH. This exposure led to a concentration-dependent increase in cell volume. Combined, these studies suggest that astrocytes exposed to EtOH accumulate compensatory organic solutes to maintain cell volume, and that in response to hyponatremia and EtOH withdrawal their volume increases to a greater extent than in cells exposed to hyponatremia alone. Furthermore, the changes associated with EtOH are osmotic in nature, and they are not reversed by anion cotransport blockers.

Localization of an insulin-like peptide in brains of two flies

A nucleotide sequence (GenBank AI134194) was identified in the database of the Berkeley Drosophila Genome Project based on the similarity of its translated sequence to insulin-like peptides known for other insects. The putative A chain of the Drosophila peptide was synthesized and used to produce an antiserum for immunocytochemistry. Medial neurosecretory cells and their axons were immunostained in whole brains of Drosophila larvae and adults. In larvae, immunostained axons from these cells extended to the corpus cardiacum in the ring gland and the hypocerebral ganglion and along the aorta in the head. In adults, axons from these cells extended along the aorta to the corpus cardiacum-hypocerebral ganglion complex near the cardiac valve and branched along the midgut and crop. In contrast, two clusters of lateral neurosecretory cells and their axons were immunostained weakly in brains of female mosquitoes, Aedes aegypti. No other cells were stained in the nervous systems or midguts of Drosophila larvae and adults or Ae. aegypti females. These specific localizations substantiate the existence of an endogenous insulin-like peptide in Drosophila and suggest that a similar peptide is present in the distantly related mosquitoes.

Distribution of ovary ecdysteroidogenic hormone I in the nervous system and gut of mosquitoes

Ovary ecdysteroidogenic hormone I (OEH I) is a gonadotropin in the female mosquito, Aedes aegypti. Whole-mount immunocytochemistry using OEH I antisera revealed an extensive distribution of immunostained cells in larvae and adults of this mosquito comparable to that observed in the African malaria mosquito, Anopheles gambiae. Medial neurosecretory cells were stained in brains of larvae and adult Ae. aegypti. In An gambiae the lateral neurosecretory cells were stained more often. In both species, immunostained axons from these cells extended out of the brain through the neurohemal organ associated with the aorta and branched extensively along the midgut. Immunostained endocrine cells were observed in larval and adult midguts of both species. In adults, abdominal metameric perivisceral organs were stained. Stained axons interconnected the perivisceral organs and neurosecretory cells in the abdominal ganglia. Episodic release of OEH I from these organs was evident in female Ae. aegypti, when staining disappeared at 12 hours after a blood meal and returned by 48 hours to levels observed before and up to 2 hours after the blood meal. Two sites were specifically stained only in An. gambiae: an axon net around the pyloric valve in the hindgut of larvae and adults and a ring of endocrine cells in the cardiac valve in the larval midgut. The markedly similar localizations of immunostained cells in larvae and adults of two distantly related species indicate that OEH I, or a homolog, is conserved within this group of Diptera and likely has stage- and sex-specific functions.

Coexpression of microsomal-type prostaglandin E synthase with cyclooxygenase-2 in brain endothelial cells of rats during endotoxin-induced fever

Fever is triggered by an elevation of prostaglandin E(2) (PGE(2)) in the brain. However, the mechanism of its elevation remains unanswered. We herein cloned the rat glutathione-dependent microsomal prostaglandin E synthase (mPGES), the terminal enzyme for PGE(2) biosynthesis, and examined its induction in the rat brain after intraperitoneal injection of pyrogen lipopolysaccharide (LPS). In Northern blot analysis, mPGES mRNA was weakly expressed in the brain under the normal conditions but was markedly induced between 2 and 4 hr after the LPS injection. In situ hybridization study revealed that LPS-induced mPGES mRNA signals were mainly associated with brain blood vessels, especially vein or venular-type ones, in the whole brain area. Immunohistochemical study demonstrated that mPGES-like immunoreactivity was expressed in the perinuclear region of brain endothelial cells, which were identified as von Willebrand factor-positive cells. Furthermore, in the perinuclear region of the endothelial cells, mPGES was colocalized with cyclooxygenase-2 (COX-2), which is the enzyme essential for the production of the mPGES substrate PGH(2). Inhibition of cyclooxygenase-2 activity resulted in suppression of both PGE(2) level in the CSF and fever (Cao et al., 1997), suggesting that the two enzymes were functionally linked and that this link is essential for fever. These results demonstrate that brain endothelial cells play an essential role in the PGE(2) production during fever by expressing COX-2 and mPGES.

The ARG tyrosine kinase interacts with Siva-1 in the apoptotic response to oxidative stress

The Abl family of mammalian nonreceptor tyrosine kinases consists of c-Abl and ARG (Abl-related gene). Certain insights are available regarding the involvement c-Abl in the response of cells to stress. ARG, however, has no known function in cell signaling. The present studies demonstrate that ARG associates with the proapoptotic Siva-1 protein. The functional significance of the ARG-Siva-1 interaction is supported by the finding that ARG is activated by oxidative stress and that this response involves ARG-mediated phosphorylation of Siva-1 on Tyr(48). The proapoptotic effects of Siva-1 are accentuated in cells stably expressing ARG and are inhibited in ARG-deficient cells. Moreover, the proapoptotic effects of Siva-1 are abrogated by mutation of the Tyr(48) site. We also show that the apoptotic response to oxidative stress is attenuated in ARG-deficient cells and that this defect is corrected by reconstituting ARG expression. These findings support a model in which the activation of ARG by oxidative stress induces apoptosis by a Siva-1-dependent mechanism.

Computer simulation of temperature changes in a wheat storage bin

A mathematical model describing the transient temperature distribution of grain in a cylindrical storage bin with mixed boundaries is presented and solved using the finite element method. Using the typical meteorological data of a region such as temperate China, temperature changes of wheat in a storage bin are simulated and analysed in detail. Simulated results indicate that high temperature accumulation areas of the grain are in the bin centre and near the bin bottom or at the top surface of the grain throughout the whole year and ventilation under appropriate weather conditions is necessary. This method can be used to develop and evaluate aeration control strategy and reduce the need for chemical treatments of grain during storage.

[Induction of protective immune responses in rhesus monkey by immunization with recombinant plasmids of polyvalent epitopes of Plasmodium falciparum using cholera toxin B as adjuvant]

The immunogenicity and protective efficacy of the DNA vaccine which include cholera toxin B subunit (CTB) and polyvalent protective epitopes of Plasmodium falciparum (awte gene) was assessed using rhesus monkeys as animal models. Recombinant plasmids of pCMV-CTB-AWTE were given to five rhesus monkeys three times with two weeks intervals by intramuscle (i.m.) route, immunization dose was 500 micrograms per plasmid per animal. High levels of anti-CTB and anti-malaria epitopes antibodies and P. falciparum epitope specific CTL activity were elicited. The vaccinated groups was challenged with 1.25 x 10(8) of P. cynomolgi parasites. All monkeys of the control group was patent for at least 34 days, the DNA vaccinated groups wasn't infected during the 60 days we detected. The cocktail DNA vaccine which contains multi-stage and multi-epitope antigen gene shows excellent immunogenicity and protective efficacy, the results also suggests that DNA vaccine plays an important role against malaria infection.

[A study on the bioavailability of fluoride added into milk]

OBJECTIVE

To assess the bioavailability of fluoride added into milk.

METHODS

Eight subjects were studied by testing fluoride levels in blood and urine samples collected after drinking fluoridated milk and fluoridated water respectively, according to pharmacokinetics and cross control method.

RESULTS

The bioavailability of fluoride in fluoridated milk reached 80.2% in blood analysis and 84.8% in urine analysis. The result was about 20.0% lower as compared with fluoridated water.

CONCLUSION

Fluoride bioavailability in fluoridated milk is still high and sufficient.

[Translation initiation function of the regulation element in the operon of cholera toxin A]

To demonstrate that there existed translation coupling between cholera toxin A subunit gene and B subunit gene, and give the answer why the expression level of B gene is five times more than that of A gene, alpha report system for the investigation of translation coupling was constructed by using lacZ gene as reporter. Frame-shift mutation was introduced near the C terminal of ctxA gene, and the ribosome would read through its normal stop codon. The report plasmid was constructed and it was found that the expression level of lacZ gene decreased five times after the frame-shift mutation. The translation of cholera toxin B subunit gene was translational coupled with A subunit gene, and was responsible for the differential expression level of the two genes.

[A new model of translational control of gene expression in polycistron++ of AB5 entrerotoxin]

The expression level of the B subunit gene of cholera toxin (ctx) and E. coli heat labile toxin (ltx) is five to seven times more than that of A subunit gene. In these studies, a 80 basepair translation regulation element was found located in the structure gene of A gene of both toxin operon which consists of three translation initiation region. Site-directed mutation of the initiation codon of TIR3 resulted in the 9 time decrease of the expression of the downstream cistron which was translational coupled with A gene. The results indicated that translation from the internal of A gene and translation coupling are responsible for the differential expression level of the A and B gene of AB5 enterotoxin.

X-Ray structures of the universal translation initiation factor IF2/eIF5B: conformational changes on GDP and GTP binding

X-ray structures of the universal translation initiation factor IF2/eIF5B have been determined in three states: free enzyme, inactive IF2/eIF5B.GDP, and active IF2/eIF5B.GTP. The "chalice-shaped" enzyme is a GTPase that facilitates ribosomal subunit joining and Met-tRNA(i) binding to ribosomes in all three kingdoms of life. The conserved core of IF2/eIF5B consists of an N-terminal G domain (I) plus an EF-Tu-type beta barrel (II), followed by a novel alpha/beta/alpha-sandwich (III) connected via an alpha helix to a second EF-Tu-type beta barrel (IV). Structural comparisons reveal a molecular lever, which amplifies a modest conformational change in the Switch 2 region of the G domain induced by Mg(2+)/GTP binding over a distance of 90 A from the G domain active center to domain IV. Mechanisms of GTPase function and ribosome binding are discussed.

[An analysis on need and demand for dental service in urban residents of Beijing]

OBJECTIVE

To analyze the needs and demands for dental services in urban residents of Beijing, and to forecast developmental trends of dental demand in the future.

METHODS

There were 1,517 subjects examined by a stratified, clustering, random sampling, and a questionnaire survey were completed.

RESULTS

The prevalence of oral diseases was 97.6%, but only 31.5% of subjects visited the dentist in a year, the total number of residents who had need of dental care were 4,412,010 more than that of demand level. Potential demand was mainly due to the negative awareness of people and problem from service provider. It was predicted that, if the potential demand caused by awareness and service provider were satisfied, the demand for dental care would increase by 69.4% and 13.2%, respectively. By the year of 2005, the demand will increase by 1.14%, and the value will be 3.76% in 2010.

CONCLUSIONS

A substantial discrepancy is found between oral disease presence and demand for dental service. The levels of demand are also irrational. The large potential demand is caused by both receiver and provider's factors. At last, the future demand for dental care is forecasted under three hypothesis.

Molecular electronegative distance vector (MEDV) related to 15 properties of alkanes

Several quantitative structure-property relationship (QSPR) models between 15 basic physical properties or thermodynamic functions of alkanes and their molecular electronegative distance vectors (MEDV) are developed. For six of the properties-boiling point (BP), density (D) at 25 degrees C, refraction index (RI) at 25 degrees C, critical temperature (CT), critical pressure (CP), and surface tension (ST) at 20 degrees C-logarithmic models are found to give better results than conventional (linear) models since the values of these properties all tend to a limit with increasing carbon chain length. All models are created using multiple linear regression (MLR). Conventional models are proposed for the remaining nine physical properties or thermodynamic functions: molar volume (MV) at 20 degrees C, molar refraction (MR) at 20 degrees C, heat capacity (HC) at 300 K, enthalpy (E) at 300 K, heats of vaporization (HV) at 25 degrees C, heat of atomization (HA) at 25 degrees C, standard heat of formation (HF) at 25 degrees C, heat of formation in liquid (HFL) at 25 degrees C, and heat of formation in gas (HFG) at 25 degrees C.

Pseudosubstrate inhibition of protein kinase PKR by swine pox virus C8L gene product

The interferon-induced protein kinase PKR is activated upon binding double-stranded RNA and phosphorylates the translation initiation factor eIF2alpha on Ser-51 to inhibit protein synthesis in virally infected cells. Swinepox virus C8L and vaccinia virus K3L gene products structurally resemble the amino-terminal third of eIF2alpha. We demonstrate that the C8L protein, like the K3L protein, can reverse the toxic effects caused by high level expression of human PKR in yeast cells. In addition, expression of either the K3L or C8L gene product was found to reverse the inhibition of reporter gene translation caused by PKR expression in mammalian cells. The inhibitory function of the K3L and C8L gene products in these assays was found to be critically dependent on residues near the carboxyl-termini of the proteins including a sequence motif shared among eIF2alpha and the C8L and K3L gene products. Thus, despite significant sequence differences both the C8L and K3L proteins function as pseudosubstrate inhibitors of PKR.

[Rainfall interception capacity of forest canopy between two different stands]

Based on the observation data, the rainfall interception capacity of the canopy in plantation and natural forest stands and its relation to rainfall were examined using the method of taking maximum under the same rainfall. The results showed that the rainfall interception capacity of plantation forest increased rapidly with the increase of rainfall, because of its even distribution of branches and leaves, which was higher under low rainfall less than 30 mm, and the saturation interception capacity was easily reached, depending on the quantity of branches and leaves in the canopy. Although the interception capacity of natural forest was relatively weak under low rainfall less than 30 mm, compared with plantation forest, it was much stronger under heavy rainfall more than 30 mm. The saturation interception of natural forest was larger than that of plantation forest.

[The role of IL-1 beta and TNF-alpha in hyper-reactivity of neutrophils in rapidly progressive periodontitis patients]

OBJECTIVE

Neutrophils (PMNs) from rapidly progressive periodontitis (RPP) was found to generate abnormally high levels of oxygen radicals. Elastase activity in gingival crevicular fluid (GCF) from RPP was also found much higher. It suggested that PMNs in some RPP patients are hyper-reactive. The purpose of this study was to investigate the mechanism of PMN hyper-reactivity by surveying the correlation of TNF-alpha level with elastase activity in GCF and by evaluating the association between PMN infiltration and the expression of IL-1 beta and TNF-alpha in gingival tissues from RPP patients.

METHODS

41 GCF samples from 22 RPP patients and 34 GCF samples from 11 healthy controls were collected. The total amount of TNF-alpha in GCF was detected using ELISA. The elastase activity was measured with a low molecular weight substrate (S2484) specific for granulocyte. The correlation of TNF-alpha level with elastase activity in a GCF sample was analyzed with Spearman correlation. 20 gingival specimens were obtained respectively from 10 RPP patients and 5 periodontally healthy controls. The expression of IL-1 beta and TNF-alpha was detected with immunohistochemistry. The distribution of PMN was observed with hematoxylin and eosin staining.

RESULTS

Total amount of TNF-alpha in GCF was positively correlated with elastase activity (r = 0.44, P < 0.05). The IL-1 beta- and TNF-alpha-positive cells in gingiva were superimposed in areas where PMNs infiltration predominant.

CONCLUSION

The hyper-reactivity of PMN in RPP patients was related to locally produced IL-1 beta and TNF-alpha.

[The effect of non-surgical periodontal and adjunctive minocycline-HCL treatments on collagenase activity]

OBJECTIVE

To evaluate the effect of scaling and root planing combined with local application of 2% minocycline hydrochoride ointment(Periocline) on the level of collagenase activity releasing from PMNs in GCF.

METHODS

This was a randomized, single-blinded, split mouth design study. The target sites of 31 patients with moderate to severe periodontitis (PD > 5 mm) was randomized by left-side and right-side into one of the two groups (the test group and the control group). Subsequently each patient was scheduled for two appointments for the full-month supra-gingival scaling and oral hygiene instruction. At baseline all patients received subgingival scaling and root planing and were followed by 4-time applications of Periocline with one-week interval for totally four weeks in the test group. All patients were taken GCF for measuring collagenase by the method of Nakashima et al (1996) and were examined based on four parameters, including plaque index, pocket depth, attachment loss and bleeding on probing.

RESULTS

Four weeks after root planing with 4-time applications of Periocline, all clinical parameters and active collagenase in GCF decreased significantly in the test groups[(593 +/- 112) mU/sample vs (311 +/- 98) mU/sample, P < 0.001]. On the other hand, simple root-planing therapy had limited effect on the active collagenase[(611 +/- 123) mU/sample vs (523 +/- 127) mU/sample], although all clinical parameters were also reduce significantly. Interestingly, seven weeks later, gingival inflammation and the active collagenase were reduced more significantly than those after four-week root planing in both groups[Test: (311 +/- 98) mU/sample vs (207 +/- 57) mU/sample;

CONTROL

(523 +/- 127) mU/sample vs (345 +/- 117) mU/sample, P < 0.001]. At eleven week, gingival inflammation and the level of collagenase activity were rebounded in the control group[(467 +/- 108) mU/sample]. However, in the test group they were kept in lower level[(213 +/- 121) mU/sample]. The level of collagenase activity showed significantly positive correlation with GCF volumes and AL in two groups.

CONCLUSION

These results indicate that local application of 2% minocycline hydrochoride ointment may effectively inhibit the level of active collagenase from PMNs and may inhibit connective tissue breakdown by inhibiting neutrophil collagenase.

Peri-implant mucosal inflammation and bone loss: clinical and radiographic evaluation of 108 dental implants after 1-year loading

OBJECTIVE

To evaluate the clinical outcomes, and a possible correlation between peri-implant mucosal inflammation and marginal bone loss, 1 year after restoration in a group of Chinese patients with dental implants.

METHODS

Observation of the clinical and radiographic parameters of 108 IMZ and Frialit-2 dental implants in 70 patients.

RESULTS

One year after loading, there were no signs of mobility and peri-implant radiolucency in any of the implants. The average bone loss adjacent to implants was 0.63 mm (SD 0.78). The prevalence of peri-implant mucosal inflammation, as indicated by sulcus bleeding index (SBI) of 1.0 or more, was 32.9%. Significant positive correlation was found between mucosal inflammation and bone loss (P < 0.05). 92% of the observed sites had plaque index (PLI) scores greater than 1.

CONCLUSIONS

The 1-year outcomes from this patient group indicate that IMZ and Frialit-2 implants provide satisfactory clinical results. One of the etiologic factors of alveolar bone loss around implants seems to be plaque-associated marginal inflammation. Improvement of oral hygiene, elimination of soft tissue inflammation, and proper treatment of periodontal disease of natural teeth are critical for maintaining the implants.

[Assessment of malaria DNA vaccines in mice and monkeys]

Cholera toxin B subunit is a good carrier protein and an effective adjuvant which can boost both cellular and humoral immunity. DNA fragments encoding B cell, Th cell and CTL epitopes of P. falciparum CS, MSA-1, MSA-2 and RESA antigens were cloned down-2 stream of cholera toxin B subunit gene in the same reading frame. High titer of anti-malaria epitopes antibodies and strong cellular immunogenicity were elicited after Balb/c mice were immunized three times with 100 micrograms recombinant plasmid DNA dissolved in 100 microliters PBS. A total of 120 vaccinees were challenged with mouse Plasmodium yoelli to investigate if cross protection existed. The protective efficacy was about 60%-80%. Four rhesus monkeys were challenged with 10(8) of P. cynomalgi, better results were obtained in the groups immunized with mixed plasmids including NANP, AWTE.

2-year observation of attachment loss in a rural Chinese population

BACKGROUND

Risk indicators for periodontitis seem to vary with study population. The purpose of this study was to determine whether risk indicators of additional attachment loss differ between generations of Chinese villagers in a rural area of China over a 2-year period.

METHODS

The study population consisted of 310 subjects aged 15 to 44. In each subject, 2 quadrants from either the upper or lower jaw were randomly selected and 6 sites on each tooth were examined. Clinical parameters included plaque scoring system (PSS), calculus index (CI), probing depth (PD), attachment level (AL), and sulcus bleeding index (SBI). The second examination was done 2 years after the first.

RESULTS

In the 15- to 24-year-old age group, mean PSS, CI, and SBI were significantly higher in subjects with additional attachment loss > or =3 mm (AL+) than in those without attachment loss (AL-). In the 25- to 34-year-old age group, mean PD was significantly higher in AL+ than in AL-, and mean PD and AL were significantly higher in AL+ than in AL- in the 35- to 44-year-old age group. Although the number of subjects with AL+ increased with age, the mean number of sites with AL+ per subject did not differ by generation. In addition, smokers tended to exhibit attachment loss more often than non-smokers.

CONCLUSIONS

The present results suggest that the clinical parameters associated with attachment loss differ between generations and that gingival inflammation is likely associated with the onset of periodontitis more strongly than progression of periodontitis, whereas PD and/or AL are associated with the progression of periodontitis.

High-level expression of a truncated wall-associated protein A from the dental cariogenic Streptococcus mutans

Streptococcus mutans plays a primary role in the formation of dental caries. Previously, in our laboratory, an S. mutans genomic library was prepared, and the wapA gene was cloned into the shuttle vector, pSA4/4B2. To generate overexpression of wapA and to facilitate efficient purification of the WapA protein for use as an immunogen, an expression vector with the strong tac promoter was used. In order to answer questions regarding the optimization of solubility and expression based on gene size or the hydrophobicity of the protein product, 12 truncated constructs of the wapA gene were prepared using PCR. The truncated products were subcloned into the pGEX-6P-1 glutathione S-transferase (GST) fusion vector and expressed in E. coli BL21. The fusion proteins were analyzed by SDS-PAGE and confirmed by analysis with anti-GST and anti-WapA antibodies. Our study suggests that abrogation of the wapA promoter is necessary for expression of this gene in this expression system. Deletion of the signal peptide and the hydrophobic C terminus of WapA increased expression compared with the full-length construct, and truncation at the protease cleavage site of the C-terminal region greatly increased the stability of the protein without a loss in reactivity with the anti-WapA antibody. Western immunoblot analysis with anti-WapA antiserum clearly showed that the majority of the epitopes of the GST-WapA fusions are located in the N-terminal region of WapA. The immunogenicity of the various WapA fusion products is being examined in mice and rats to further map the immunologically dominant regions of the protein. This method effectively increased the expression of WapA and should contribute to the further understanding of gene expression of E. coli, as well as aid in the characterization of this protein for future immunologic evaluation.

[A one-year study on enzyme level in gingival crevicular fluid around osseointegrated dental implants]

OBJECTIVE

To investigate the changes of gingival crevicular fluid(GCF) volume, aspartate aminotransferase (AST) and alkaline phosphatase(ALP) levels in GCF around dental implants during the first year after rehabilitation. And to explore the relationships between these changes and peri-implant inflammation as well as bone loss.

METHODS

26 Branemark implants in 12 adults were included in this study. Examinations were carried out in a total of 52 sites in preinsertion period and 3, 6, 12 months following rehabilitation.

RESULTS

GCF volume, GCF-AST, GCF-ALP were firstly increased and then fallen during the first year after rehabilitation. GCF volume, GCF-AST, GCF-ALP in sites with peri-implant mucositis were higher than those in health sites, and were increased with the severity of peri-implant mucositis. GCF volume, GCF-AST, GCF-ALP in sites with bone loss were significantly higher than those without bone loss.

CONCLUSION

GCF volume, GCF-AST, GCF-ALP could reflect peri-implant inflammation and bone changes to some degree.

[Ecological process of vegetation restoration in Caragana mirophylla sand-fixing area]

The occurrence and development of artificial vegetation after mobile sandy dunes being fixed by adopting straw check combining with seeding Caragana microphylla were studied. Especially the process of species invasion and the changes of community structure in 35 years were analyzed in detail. The results showed that the species richness of artificial community of C. microphylla increased, from 5 species (in 2 years) to 23 species in 35 years. In the structure concerning plant lifeform, therophytes were in dominant position, while the ratio of therophytes to all plant species had a tendency of decrease. The rates of species number and the quantity of hemicryptophytes and geocryptophytes increased gradually. Species diversity and community evenness indexes increased and ecological dominance index decreased gradually. The similarity index of the artificial plant community to natural one increased with age. The changes of physical and chemical property of soil were also discussed.

[Induction of protective immune response in mice and rhesus monkeys by immunization with fusion protein of cholera toxin B subunit and multiples of Plasmodium falciparum]

Recombinant fusion protein of cholera toxin B subunit (CTB) and poly-valent protective epitopes of plasmodium falciparum was given to i.m. to C57BL/6j mice and rhesus monkeys three times. In rhesus monkeys, high level of antibodies for CTB (1:6400) and malaria epitopes (1:3200) amtobpdoes were elicited as well as the specific CTL activity for P. plasmodium. After the mice were challenged with sporozoites of P. yeolli, about 50% of them were protected from the patent infection. A blood-stage challenge with 10(8) of P. cynomolgi parasite were given to rhesus monkeys, which showed that two animals in control group were patent infection for at least 30 days, in contrast, the two animals immunized were recovered respectively at the day of 11 and 15 after challenges. The results suggested that cholera toxin acts as an effective adjuvent in the development of malaria vaccine.

[Titer and avidity of serum antibody to Porphyromonas gingivalis before and after periodontal therapy]

OBJECTIVE

To observe the changes of titer and avidity of serum antibody to Porphyromonas gingivalis (Pg) before and one month after periodontal therapy, and to observe the correlation of titer and avidity of anti-Pg IgG with clinical indices.

METHODS

ELISA and DEA-ELISA were used to determine the titer and avidity of serum IgG antibody to Pg381 before and one month after periodontal treatment in 17 periodontitis patients and 6 healthy control subjects.

RESULTS

The titers of anti-Pg IgG antibody were higher in periodontitis patients than in healthy control subjects (P < 0.001). All patients were seropositive (titers to Pg were higher than 2-fold above the median for control subjects). IgG antibody avidity to Pg in periodontitis patients were not found to be significantly lower than that in control group. The titers to Pg decreased significantly at one month after periodontal therapy, but antibody avidity didn't change. Serum anti-Pg antibody titers had a tendency of negative correlation with probing depth. The antibody titers were significant higher in periodontitis patients with < or = 5 mm mean probing depth than in patients with > 5 mm mean probing depth.

CONCLUSIONS

It is suggested that the humoral immune response to Pg381 is protective and this protective effect mainly depends on the titer of antibody.

Characterization of a novel human immunodeficiency virus type 1 neutralizable epitope within the immunodominant region of gp41

Previously, we generated human monoclonal antibodies using peripheral blood mononuclear cells from an asymptomatic human immunodeficiency virus type 1 (HIV-1)-seropositive donor. One of these monoclonal antibodies (designated clone 3, CL3) recognized 10 amino acids (GCSGKLICTT) within the immunodominant region (cluster I) of the transmembrane envelope glycoprotein gp41 and neutralized infection of target cells with different laboratory isolates. Because the epitope recognized by CL3 has two cysteine residues that could potentially produce a disulfide loop in gp41, we analyzed binding of our monoclonal antibody to the cyclic and linear motif of the peptide sequence IWGCSGKLICTTAVP (residues 600-614). The CL3 antibody did not bind to the synthetic cyclic peptide but did recognize the linear form. Two polyclonal rabbit sera against both the linear and cyclic peptides were then generated. Both antisera bound to viral glycoproteins gp41 and gp160, but neither sera neutralized HIV-1 laboratory isolates. Using a set of alanine-substituted IWGCSGKLICTTAV peptides, we analyzed binding of polyclonal antisera and CL3. The profile of binding of polyclonal antisera to these peptides was different from that of CL3 to the same peptides. This suggests that CL3 recognized a unique neutralizable core epitope, which was not immunogenic in either the cyclic or the linear IWGCSGKLICTTAVP peptides used as immunogens in the rabbits.

[Boron balance in agroecosystem on brown-red soil of south Hubei Province]

Five sequential cropping systems including rape/soybean-rice, wheat/watermelon-rice, rape/corn-soybean, wheat-sesame and soybean-sesame, were selected study the boron balance in agroecosystem on brown-red soil of south Hubei Province. The results show that the main output of boron was runoff and leaching, which accounted for 48-53% and 41% of the total respectively, while the output by products accounted for 3.4-10.1%. The main inputs were from rainfall, irrigation, fertilization seeds and seedlings, and natural return.

[Changes of elastase in gingival crevicular fluid after periodontal treatment of adult periodontitis patients]

OBJECTIVE

To examine the changes of elastase in the supernatant (EA-s) and in the pellet (EA-p) after centrifuge in gingival crevicular fluid (GCF) before and after periodontal treatment.

METHODS

GCF was sampled with filter paper strips by intra-pocket method to determine EA levels. Forty-three teeth of eight subjects were included. EA-s and EA-p were determined separately using the subtract Meosuc-ala-ala-val-pro-NA.

RESULTS

EA-s per site and per ml, EA-p per site and the ratio of EA-s/EA-p (S/P) decreased significantly after non-surgical periodontal treatment (P < 0.001), while EA-p concentration didn't change (P > 0.05).

CONCLUSIONS

GCF-EA-s and EA-p could act as objective parameters to evaluate the effect of periodontal therapy, especially EA-s and S/P, which may be sensitive diagnostic parameters for determining periodontal disease activity.

Leukocyte functions in 2 cases of Papillon-Lefèvre syndrome

AIM

To investigate the rôle of leukocytes in the pathogenesis of Papillon-Lefevre syndrome (PLS).

METHODS

Peripheral blood polymorphonuclear neutrophils (PMNs), monocytes (MNs) and gingival crevicular fluid (GCF) were obtained from 2 cases of PLS with typical features. The chemotaxis of PMNs and MNs were evaluated using a modified Boyden chamber. The adherence of PMNs was determined by adherence of PMNs to petri dishes. Interleukin-8 (IL-8) in GCF was detected by sandwich ELISA. Elastase activity in GCF was measured with a low molecular weight substrate (S-2484) specific for granulocyte elastase.

RESULTS

PMNs from both patients showed depressed chemotactic response to FMLP and IL-8. Total amounts of IL-8 in GCF from the 2 patients were much higher than those of the normal controls. Elastase activity was not significantly different from that of the controls. The adherence of PMN and the chemotaxis of MN in the 2 patients were normal.

CONCLUSION

The depressed chemotactic response of PMN leads to decreased recruitment of PMN and/or release of lysozyme from PMN in the diseased gingival tissue, increasing the susceptibility of PLS patients to periodontal infection.

[Relevance of Fc gamma R polymorphism to the susceptibility of early-onset periodontitis]

OBJECTIVE

To investigate the polymorphism of the Fc gamma R genotype and its association with the susceptibility of early-onset periodontitis (EOP).

METHODS

DNA of the white blood cells from 33 subjects with EOP and 27 healthy controls was extracted. Genotypes of the Fc gamma RIIA and Fc gamma RIIIB were determined by PCR followed by BstUI restriction endonuclease digestion and DNA sequencing, respectively. Then compared the differences in distribution of each genotype.

RESULTS

No statistical difference in distribution of Fc gamma RIIA was observed between patients and controls. However, a significant over-representation of the Fc gamma RIIIB NA1/NA1 was found in EOP.

CONCLUSION

These results suggest that the Fc gamma RIIIB NA1/NA1 may be a risk indicator for the susceptibility of the EOP.

[Gingival crevicular fluid enzyme levels at different destruction sites in the same teeth]

OBJECTIVE

To direct selecting proper sampling methods and sites in clinical research.

METHODS

Gingival crevicular fluid (GCF) was sampled separately at the mesial-buccal and distal-buccal sites in the same teeth, which were destroyed differently. Clinical parameters were recorded in the subject sites and its adjacent sites. Aspartate Aminotransferase (AST) and Alkaline Phosphatase (ALP) in the GCF were determined. Difference of the enzyme levels between the two sampling sites, and relations between the enzyme level and all the clinical parameters were assessed.

RESULTS

GCF-AST, ALP per sample at severely diseased sites were much higher than that from healthy and/or mild sites in the same teeth. Significant positive correlation (P < 0.001, r > 0.5) was demonstrated between enzyme levels in the sampling sites and probing depth (PD) and attachment level (AL) of the lingual sites. However, there was mild significant correlation (P < 0.05, r = 0.275) between ALP level in the sampling sites and PD of the proximal-buccal sites of its adjacent teeth. No significant correlation (P > 0.05) was found between AST level in the sampling sites and PD, AL of the adjacent teeth sites, and also between ALP level in the sampling sites and AL of the adjacent teeth sites.

CONCLUSION

Site-specificity of periodontal disease was further demonstrated. GCF components were influenced reciprocally more obviously in the same proximal than by other sites.

[Effect of tian ma cu zhi chongji medicinal granules (TMCZCJ) on blood rheology in hypostasis rats due to stagnation of liver-qi and learning-memory disorder in cerebral ischemia-reperfusion mice]

OBJECTIVE

To investigate the effect of TMCZCJ on the blood rheology in hypostasis rats due to stagnation of the liver-qi and on the learning-memory disorder in cerebral ischemia-reperfusion mice.

METHOD

The models of hypostasis due to stagnation of the liver-qi were made by combining irritation with hypodemic injected adrenalin and ice-bath in rats, and the models of learning-memory disorder were made by repeatedly ligating-reperfusing the bilateral carotid in mice. The hypostasis rats and learning-memory disorder mice were perorally administrated TMCZCJ(7.7, 15.4 g.kg-1) once a day, for fourteen consecutive days.

RESULT

TMCZCJ can significantly reduce plasma viscosity, blood viscosity and reduced viscosity in hypostasis rats. It can also improve the latent learning-memory capability and memory gain-repetition ability in water-maze for cerebral ischemia-reperfusion mice.

CONCLUSION

TMCZCJ can improve remarkably blood rheology in hypostasis rats and learning-memory disorder in cerebral ischemia-reperfusion mice.

Artifact detection in the PO2 and PCO2 time series monitoring data from preterm infants

BACKGROUND

Artifacts in clinical intensive care monitoring lead to false alarms and complicate later data analysis. Artifacts must be identified and processed to obtain clear information. In this paper, we present a method for detecting artifacts in PCO2 and PO2 physiological monitoring data from preterm infants. PATIENTS AND DATA: Monitored PO2 and PCO2 data (1 value per minute) from 10 preterm infants requiring intensive care were used for these experiments. A domain expert was used to review and confirm the detected artifact.

METHODS

Three different classes of artifact detectors (i.e., limit-based detectors, deviation-based detectors, and correlation-based detectors) were designed and used. Each identified artifacts from a different perspective. Integrating the individual detectors, we developed a parametric artifact detector, called ArtiDetect. By an exhaustive search in the space of ArtiDetect instances, we successfully discovered an optimal instance, denoted as ArtiDetector.

RESULTS

The sensitivity and specificity of ArtiDetector for PO2 artifacts is 95.0% (SD = 4.5%) and 94.2% (SD = 4.5%), respectively. The sensitivity and specificity of ArtiDetector for PCO2 artifacts is 97.2% (SD = 3.6%) and 94.1% (SD = 4.2%), respectively. Moreover, 97.0% and 98.0% of the artifactual episodes in the PO2 and PCO2 channels respectively are confirmed by ArtiDetector.

CONCLUSIONS

Based on the judgement of the expert, our detection method detects most PO2 and PCO2 artifacts and artifactual episodes in the 10 randomly selected preterm infants. The method makes little use of domain knowledge, and can be easily extended to detect artifacts in other monitoring channels.

Induction of diagnostic test strategies with multi-level information measures

This paper presents a method for inducing clinical diagnostic test protocols or strategies from data. We represent testing strategies as a strategy tree. To support induction of strategy tree, we define three information measures: K-level information, K-level information gain, K-level gain ratio, and K-level cost index, for test selection during strategy building. These measures generalize Quinlan's information measures used in decision tree induction. We present theoretical and experimental results to show that the K-level cost index can be used to induce strategy trees in a practical domain.

[Clinical evaluation of gingival sulcus temperature in healthy subjects]

OBJECTIVE

To evaluate gingival sulcus temperature in healthy subjects.

METHODS

Small size, high sensitivity and rapid response thermocouple was used to measure the gingival sulcus temperature in seven dental students with healthy periodontium. 28 teeth in each subject were tested.

RESULTS

For an individual subject, the gingival sulcus temperatures in all sites were always lower than sublingual temperature. There was obviously increased temperature gradient from anterior teeth to posterior teeth. The mean gingival sulcus temperatures on buccal sites were lower than that on lingual sites. There was no significant difference between maxillary and mandibular corresponding sites on lingual side. However, mandibular temperature was significantly lower than maxillary temperature on buccal side. Mandibular buccal temperature was the lowest in all tooth surfaces.

CONCLUSION

Gingival sulcus temperature in subjects with healthy periodontium is easily influenced by environmental factors.

[Genetic analysis of tooth development and eruption in 82 pairs of female-female twins]

OBJECTIVE

To study the heritability of tooth development and eruption.

METHODS

82 pairs of female-female twins between 6-12 years old were collected. Twin zygosity diagnosis were made by DNA-fingerprinting. The number of third molar present, hypodontia, upper lateral incisor malformation and the number of erupted permanent teeth were recorded by oral examination and panoramic radiographs, their heritabilities were calculated.

RESULTS

According to the level of heritability, the dental traits were aligned as follows: the number of third molars present, the upper lateral incisor malformation, hypodontia and the number of erupted permanent teeth.

CONCLUSION

Though both the tooth development and its eruption were under genetic influence, the heritability of tooth development was far more than tooth eruption.

An additional electrostatic interaction between adrenodoxin and P450c27 (CYP27A1) results in tighter binding than between adrenodoxin and p450scc (CYP11A1)

Mitochondrial cytochrome P450c27 (product of the CYP27A1 gene) is found to have significantly higher affinity for the common redox partner adrenodoxin than another mitochondrial P450, P450scc (product of the CYP11A1 gene). To investigate the basis of the approximately 30-fold difference in adrenodoxin binding, two sets of P450c27 mutants were generated, expressed in Escherichia coli, and purified. Mutations of one set were within the putative adrenodoxin-binding site containing conserved lysine residues also crucial in P450scc for binding adrenodoxin. The second set included mutations within a sequence aligning with the "meander region" of P450BM-3 proposed to be a site of redox-partner interactions in P450s (Hasemann, C. A., Kurumbail, R. G., Boddupalli, S. S., Peterson, J. A., and Deisenhofer, J. (1995) Structure 3, 41-62). Mutation of the P450c27 conserved lysines (K354A and K358A) led to a approximately 20-fold increase in apparent Ks for adrenodoxin, confirming that these two positively charged residues conserved in mitochondrial P450s are important for adrenodoxin binding. Mutation of Arg-418, conserved in the CYP27A1 family, to serine also decreased the affinity for adrenodoxin approximately 20-fold. This residue is predicted to be located in the meander region. A triple K354A/K358A/R418S mutation profoundly reduced adrenodoxin binding. Thus, in contrast to P450scc, where mutation of the two conserved positively charged residues results in virtually complete inhibition of adrenodoxin binding, in P450c27 there are three of such residues (Lys-354, Lys-358, and Arg-418) important for adrenodoxin interaction.