Oral health and dental care in modern-day China

The purpose of this paper is to present salient background information on the oral care situation and organization in China and to review epidemiological literature that has been published on adults in Chinese dental journals during the last 20 years as a context for understanding ongoing oral health research activities in China. Searches were conducted through Medline as well as Chinese language catalogues and around 30 Chinese dental journals. Most oral health surveys on adults were conducted after 1970 mainly on residents living in big cities, which are also the location of major medical universities. Surveys conducted among farmers were uncommon. Dental caries and periodontal disease were the major dental diseases studied. Only a few surveys on people's oral health knowledge, attitudes and behavior were conducted. Papers concerning dental treatment needs and utilization of dental services among adults were scarce. Sample size was usually not a major problem in these surveys but the sampling methods and diagnostic criteria used were often poorly defined. Mean DMFT scores between 2 and 6 were reported in the 35-44-year-olds and between 9 and 16 in the elderly younger than 75 years. Calculus and gingivitis were reported to be common in adult Chinese; the proportion of subjects with shallow and deep periodontal pockets was not high. Complete edentulousness in the 60-69-year-olds was usually reported to be less than 10%. About 14% of the 35-44-year-olds and 19% of the 65-74-year-olds did not brush their teeth daily.

Cosecretion of chaperones and low-molecular-size medium additives increases the yield of recombinant disulfide-bridged proteins

Attempts were made to engineer the periplasm of Escherichia coli to an expression compartment of heterologous proteins in their native conformation. As a first approach the low-molecular-size additive L-arginine and the redox compound glutathione (GSH) were added to the culture medium. Addition of 0.4 M L-arginine and 5 mM reduced GSH increased the yield of a native tissue-type plasminogen activator variant (rPA), consisting of the kringle-2 and the protease domain, and a single-chain antibody fragment (scFv) up to 10- and 37-fold, respectively. A variety of other medium additives also had positive effects on the yield of rPA. In a second set of experiments, the effects of cosecreted ATP-independent molecular chaperones on the yields of native therapeutic proteins were investigated. At optimized conditions, cosecretion of E. coli DnaJ or murine Hsp25 increased the yield of native rPA by a factor of 170 and 125, respectively. Cosecretion of DnaJ also dramatically increased the amount of a second model protein, native proinsulin, in the periplasm. The results of this study are anticipated to initiate a series of new approaches to increase the yields of native, disulfide-bridged, recombinant proteins in the periplasm of E. coli.

Characteristics and study motivation of Danish dental students in a longitudinal perspective

This survey encompasses 3 comparable datasets of newly admitted dental students in 1972 (n=236), 1982 (n=197), and 1994 (n=108). The objectives of the survey were to describe selected socio-demographic characteristics of dental students and to analyze possible changes over time as well as possible changes in the reasons reported by the students for choosing dentistry as a career, their motivations and their expectations concerning the study and the profession of dentistry. The results showed that the ratio of women to men remained unchanged at 6:4 in all 3 cohorts of students and that the students were increasingly recruited from the 2 upper social classes. The motives for choosing dentistry mainly included altruistic motives, the desire for varied work with the opportunity to put theory into practice, economic rewards, and the implicit social status. Compared to the 1972 students, those in 1994 placed greater emphasis on social status as a motive, on the opportunity to work in the biological and scientific field, and on the ready availability of work outside Denmark. The students in all 3 years had strong altruistic motives for choosing dentistry, and it would seem that this stable continuity in the cohort of dental students would ensure the continuous controlled development of dentistry in the new millennium.

Assessment of murine bladder permeability with fluorescein: validation with cyclophosphamide and protamine

OBJECTIVES

Bladder hyperpermeability should result in elevated blood levels of intravesically administered agents. Reabsorption from a hyperpermeable bladder should result in prolonged urinary excretion of an agent after parenteral administration. To test these hypotheses, urinary clearance and plasma levels of sodium fluorescein (NaF) were measured in mice before and during cyclophosphamide (CYP) and protamine-induced hemorrhagic cystitis.

METHODS

To measure the plasma uptake of NaF from the bladder, 10 mg/mL NaF was instilled, either by catheter or retrograde urethral infusion, 15 minutes before retro-orbital or ventricular sampling. The plasma levels were measured 24 hours and 14 days after exposure to CYP 300 mg/kg or 15 minutes after instillation of protamine 10 mg/mL. Hourly urine concentrations were measured immediately after intraperitoneal administration of 10 mg/kg NaF. Pretreatment samples were compared with those obtained 24 hours after intraperitoneal administration of 300 mg/kg CYP.

RESULTS

Urinary NaF excretion was delayed in CYP-exposed mice. A bi-exponential model provided an appropriate fit of the data, both before and after CYP administration. The plasma levels of NaF were significantly elevated at 24 hours and 14 days after CYP exposure when sampled by ventricular nick or retro-orbitally. The median concentration of fluorescein in the protamine-treated mice was significantly higher than in the control mice.

CONCLUSIONS

Fluorescein can be used to measure alterations in bladder permeability after bladder mucosal injury in mice. Urinary excretion of NaF is a bi-exponential process that is delayed after bladder mucosal injury, presumably because of increased mucosal permeability and resorption from the urine into the bloodstream.

The pro-sequence facilitates folding of human nerve growth factor from Escherichia coli inclusion bodies

Nerve growth factor (beta-NGF), a neurotrophin required for the development and survival of specific neuronal populations, is translated as a prepro-protein in vivo. While the presequence mediates translocation into the endoplasmic reticulum, the function of the pro-peptide is so far unknown. As the pro-sequences of several proteins are known to promote folding of the mature part, the renaturation behaviour of recombinant human beta-NGF pro-protein was compared to that of the mature form. Expression of rh-pro-NGF in Escherichia coli led to the formation of inclusion bodies (IBs). The presence of the covalently attached pro-sequence significantly increased the yield and rate of refolding with concomitant disulfide bond formation when compared to the in vitro refolding of mature NGF (rh-NGF). Physicochemical characterization revealed that rh-pro-NGF is a dimer. The pro-peptide could be removed by limited proteolysis with trypsin yielding biologically active, mature rh-NGF. Furthermore, rh-pro-NGF exhibited biological activity in the same concentration range as rh-NGF.

Utilization of dental services in Southern China

A population's utilization of dental services is an important parameter in oral health care planning, which has rarely been studied in China. The objectives of this report were to describe the dental service utilization pattern of middle-aged and elderly Chinese and to analyze the influence of selected variables on the use of dental services. A Guangdong Province population of 1,573 35- to 44-year-olds and 1,515 65- to 74-year-olds recruited from urban and rural communities was interviewed in their local dialect. It was found that 23% of the middle-aged and 24% of the elderly subjects had visited a dentist within the preceding year. The two most commonly cited reasons for not having seen a dentist for at least 3 years were: no perceived need, and no serious dental problems. Among subjects who had visited a dentist within 3 years, the 3 most commonly received treatments were: fillings, extractions, and dental prostheses. Furthermore, a logistic regression analysis showed that women, subjects who lived in urban areas, were better educated, were wealthier, and had better oral health knowledge were more likely to be a recent dental service user. In conclusion, dental service utilization among the adult Southern Chinese was found to be low, problem-driven, and influenced by some socio-economic factors.

An Oral Health Survey in Southern China, 1997: background and methodology

Relatively limited information is available about the oral health in the Guangdong Province of Southern China, the closest neighbor to Hong Kong. The study intended to explore the oral health status, knowledge, attitudes, and dental care utilization in the Guangdong population as a basis for formulating strategies for oral health prevention and treatment. Through multi-stage stratified and quota-sampling, individuals from urban as well as rural communities were selected (5- to 6-; 12-; 35- to 44-; and 65- to 74-year-olds; total N = 6251). Structured interviews and clinical examinations were performed. Inter-examiner reliability was high (kappa = 0.60-0.96). Samples of community water were taken for fluoride assessment. Overall, the sample surveyed was acceptably representative of the population, with some under-representation of rural residents and agricultural workers. Re-weighting was performed in appropriate analyses. The data analysis model used in the Second International Collaborative Study was used as a guide for the present data analysis. This approach has not previously been used on a Mainland Chinese population.

Coronal and root caries in Southern Chinese adults

Southern China is the most prosperous part of China, but information useful for oral care planning is very limited. A large-scale epidemiological survey was conducted in 1996-97. The objectives of this report were to describe the coronal and root caries of the adult Southern Chinese and to analyze the influence of selected demographic and socio-economic factors on the disease pattern. A total sample of 1,573 35- to 44-year-olds and 1,515 65- to 74-year-olds from 8 urban and 8 rural survey sites in Guangdong Province participated in an oral health interview and underwent clinical examination. World Health Organization examination procedures and diagnostic criteria were used. The weighted mean DMFT scores of the middle-aged and the elderly subjects were 4.8 and 16.1, respectively. People living in rural areas had a higher DMFT score than those living in urban areas (4.9 vs. 4.3 in the 35- to 44-year-olds and 16.5 vs. 14.7 in the 65- to 74-year-olds). In both age groups, MT was the major component of the DMFT score. Analysis of covariance showed that women and those who were economically less well off had higher DMFT scores in both age groups. The weighted prevalence rates of decayed/filled roots were 12% and 37%, with a mean of 0.2 and 0.7 teeth affected, in the middle-aged and the elderly, respectively. In conclusion, socio-economic factors had a considerable effect on the dental caries status of adults in Southern China.

Oral health status and oral health behaviors in Chinese Children

The objectives of the study were to describe the oral health status and treatment needs of the 5- to 6-year-old and 12-year-old children in Southern China; to describe the patterns of oral health behaviors, knowledge, and attitudes among the 12-year-olds; and to assess the effects of socio-behavioral factors on the 12-year-old children's dental caries experiences. The study sample was comprised of 1,587 5- to 6-year-old and 1,576 12-year-old urban and rural schoolchildren living in Guangdong Province. Three calibrated dentists clinically examined the children, and trained interviewers interviewed the 12-year-olds. Caries prevalence of the 5- to 6-year-old children was high (urban 78% vs. rural 86%); the mean dmft of the urban and rural children was 4.8 and 7.0, respectively. The caries prevalence and mean DMFT score of the 12-year-olds were 41% and 0.9 (urban) and 42% and 0.9 (rural). Only 2% of the 12-year-olds exhibited no calculus or gingival bleeding, while more than 70% had calculus. In conclusion, there is an urgent need for establishing caries-preventive activities for preschool children. The prevalence of caries among the 12-year-olds was not high, but their periodontal condition was unsatisfactory. Knowledge about gum bleeding and the use of fluoride was low. More oral health education activities should be organized, especially for the rural children.

Scaling laws in two-dimensional turbulent convection

Two-dimensional homogeneous turbulent convection is studied numerically. Though Bolgiano-Obukhov scaling is approximately valid, strong differences exist in the intermittency properties of velocity and temperature increments, where the latter are similar to those of a passive scalar. The main difference of the small-scale dynamics compared to a passive scalar arises from the Kelvin-Helmholtz instability, but this process does not affect the scaling properties. A condition for a scalar field to show the ramp-and-cliff structures of a passive scalar is discussed.

Automated noninvasive measurement of cyclophosphamide-induced changes in murine voiding frequency and volume

PURPOSE

We developed an automated noninvasive method for studying bladder function in mice. Changes in voided volume and frequency accompanying cyclophosphamide-induced cystitis were measured using computerized digital balances.

MATERIALS AND METHODS

Eight CRL CD-1 mice were given a solution of glucose and saccharin to increase urine output and studied during the dark cycle, when most voiding occurs. Urine fell directly onto electronic balance pans. The time and weight of each void was recorded. Computer programs adjusted for evaporative loss analyzed voiding data within and across sessions. After establishing stable voiding patterns 300 mg./kg. cyclophosphamide were administered intraperitoneally. The Wilcoxon signed rank test was done to compare median voided volumes, frequency and gm. per hour of urine produced before and after cyclophosphamide.

RESULTS

We implemented an automated method for voiding studies in mice. After cyclophosphamide administration the number of voids per hour increased and voided volume decreased. Some mice had as much as a 70% decrease in bladder volume and a tripling of urinary frequency. Mice responded by a sustained elevation in frequency and decreased voided volume as early as 24 hours after cyclophosphamide administration or by a pattern of delayed toxicity.

CONCLUSIONS

This noninvasive technique measures changes in mouse voiding patterns with great sensitivity and minimal effort. The method is applicable to murine models of interstitial cystitis, detrusor instability and other abnormal voiding states. It may be used for evaluating potential therapies for such conditions.

Pro-sequence assisted folding and disulfide bond formation of human nerve growth factor

Nerve growth factor (NGF) is a member of the neurotrophin family. These growth factors support neuronal survival and differentiation. Neurotrophins are synthesized as pre-pro-proteins. Whereas the pre-sequences mediate secretion, the function of the pro-peptides is largely unknown. To test the role of the pro-sequence as a folding enhancer, recombinant human pro-NGF (rh-pro-NGF) was produced in Escherichia coli. The oxidative refolding of rh-pro-NGF and rh-NGF was studied using electrospray mass spectrometry (ESIMS) time-course analysis. This analysis permitted both the identification and quantification of intermediates present during the process. The disulfide bonds formed at different times of the refolding processes were characterized by proteolytic digestion followed by matrix assisted laser desorption ionization mass spectrometry (MALDIMS) analysis. Folding yields and kinetics of rh-pro-NGF were significantly enhanced when compared to the in vitro refolding of mature rh-NGF. These results suggest that the pro-sequence of NGF promotes folding of the mature part.

Influence of the menstrual cycle on the LPS-induced cytokine response of monocytes

We previously observed a gender difference in the cytokine response of peripheral blood monocytes (PBM). The study was performed to find out whether the gender-related difference might be due to hormonal changes during the menstrual cycle in healthy premenopausal females. The release of tumour necrosis factor a (TNF-alpha) was reduced in the premenopausal females during the luteal phase compared to the follicular phase. Compared to the male controls the release of TNF-alpha and of interleukin 6 (IL-6) during the luteal phase was also diminished. In premenopausal females the concentration of estradiol in plasma correlated with the release of TNF-alpha and IL-6 during the luteal phase.

Functional specificity of the mitochondrial DnaJ protein, Mdj1p, in Saccharomyces cerevisiae

Inactivation of the gene for the mitochondrial DnaJ homolog, Mdj1p, in Saccharomyces cerevisiae results in temperature sensitivity and the loss of respiratory activity; the latter phenotype has been attributed to the loss of mitochondrial DNA. To investigate the functional specificity of Mdj1p, non-mitochondrial DnaJ proteins were targeted to mitochondria and tested for their ability to substitute for Mdj1p. The tested DnaJ proteins were able to complement the two Mdj1p-linked phenotypes, i.e., respiratory activity and growth at 37 degrees C, to different extents, ranging from full to very poor complementation. All DnaJ homologs ensured faithful propagation of the mitochondrial genome. N-terminal fragments of Mdjlp and Escherichia coli DnaJ comprising the well-characterized J domain partially substituted for Mdj1p. As the only hitherto known function of the N-terminal fragment is modulation of the substrate binding activity of the cognate Hsp70, we conclude that both Mdj1p-linked phenotypes - maintenance of respiratory activity and the ability to grow at elevated temperature - involve a mitochondrial Hsp70 partner protein.

A dibasic motif in the tail of a class XIV apicomplexan myosin is an essential determinant of plasma membrane localization

Obligate intracellular parasites of the phylum Apicomplexa exhibit gliding motility, a unique form of substrate-dependent locomotion essential for host cell invasion and shown to involve the parasite actin cytoskeleton and myosin motor(s). Toxoplasma gondii has been shown to express three class XIV myosins, TgM-A, -B, and -C. We identified an additional such myosin, TgM-D, and completed the sequences of a related Plasmodium falciparum myosin, PfM-A. Despite divergent structural features, TgM-A purified from parasites bound actin in an ATP-dependent manner. Isoform-specific antibodies revealed that TgM-A and recombinant mycTgM-A were localized right beneath the plasma membrane, and subcellular fractionation indicated a tight membrane association. Recombinant TgM-D also had a peripheral although not as sharply defined localization. Truncation of their respective tail domains abolished peripheral localization and tight membrane association. Conversely, fusion of the tails to green fluorescent protein (GFP) was sufficient to confer plasma membrane localization and sedimentability. The peripheral localization of TgM-A and of the GFP-tail fusion did not depend on an intact F-actin cytoskeleton, and the GFP chimera did not localize to the plasma membrane of HeLa cells. Finally, we showed that the specific localization determinants were in the very C terminus of the TgM-A tail, and site-directed mutagenesis revealed two essential arginine residues. We discuss the evidence for a proteinaceous plasma membrane receptor and the implications for the invasion process.

[Tracheobronchial foreign bodies]

Forty cases of children with an inhaled foreign body (FB) are reviewed over a three-year period. Clinical data, radiologic findings and complications are detailed. The nature and size of FBs are also reported. Diagnosis and management are discussed according to the most recent studies in the literature. Diagnostic flexible bronchoscopy is a useful first step when the diagnosis is unclear (i.e., choking history, unexplained respiratory symptoms), but FB removal is usually not possible during this procedure. Extraction is performed via the rigid bronchoscope under general anesthesia. However, FB could be removed with the flexible bronchoscope in five children in our study. Diagnosis and removal of an inhaled FB are required as quickly as possible in order to prevent respiratory sequelae (bronchiectasis). Prevention is based upon information to be given to families, but to the medical community as well, which often minimizes the seriousness of inhalation hazards.

Growth inhibition of cervical cancer cells by the human retinoic acid receptor beta gene

Transcription of the retinoic receptor beta (RARbeta) gene is activated in a ligand-dependent manner by the retinoic acid receptor alpha. Reduced RARbeta gene expression and loss of ligand inducibility are frequently observed in human carcinoma cells indicating that such alterations might contribute to carcinogenesis. In this study we have analyzed the influence of RARbeta on cervical cancer cell growth. Transfection of HeLa cells with RARbeta expression plasmids resulted in reduced clonal cell growth in the presence of retinoic acid (RA). RA-induced growth inhibition in HeLa x fibroblast hybrid cells was partially relieved by a dominant-negative RARbeta mutant. HeLa clones stably expressing a RARbeta transgene under control of the human beta-actin promoter [HeLa(RARbeta)] were established and analyzed for transgene-mediated growth alterations in vitro and in vivo. Anchorage-independent growth of the HeLa(RARbeta) lines was indistinguishable from that of control cells in the absence of RA, but strongly impaired after RA treatment. Reduced tumor growth of HeLa(RARbeta) clones was associated with high RARbeta protein levels. Somatic cell fusion experiments revealed that the loss of ligand inducibility of RARbeta gene expression in HeLa cells cannot be complemented by fusion with other cervical cancer cell lines. Our data indicate, firstly, that RARbeta is a negative regulator of tumor cell growth and, secondly, that cancer-associated defects in RARbeta gene expression are caused by stable, non-complementable silencing mechanisms.

Dual role of the mitochondrial chaperone Mdj1p in inheritance of mitochondrial DNA in yeast

Mdj1p, a homolog of the bacterial DnaJ chaperone protein, plays an essential role in the biogenesis of functional mitochondria in the yeast Saccharomyces cerevisiae. We analyzed the role of Mdj1p in the inheritance of mitochondrial DNA (mtDNA). Mitochondrial genomes were rapidly lost in a temperature-sensitive mdj1 mutant under nonpermissive conditions. The activity of mtDNA polymerase was severely reduced in the absence of functional Mdj1p at a nonpermissive temperature, demonstrating the dependence of the enzyme on Mdj1p. At a permissive temperature, the activity of mtDNA polymerase was not affected by the absence of Mdj1p. However, under these conditions, intact [rho(+)] genomes were rapidly converted to nonfunctional [rho(-)] genomes which were stably propagated in an mdj1 deletion strain. We propose that mtDNA polymerase depends on Mdj1p as a chaperone in order to acquire and/or maintain an active conformation at an elevated temperature. In addition, Mdj1p is required for the inheritance of intact mitochondrial genomes at a temperature supporting optimal growth; this second function appears to be unrelated to the function of Mdj1p in maintaining mtDNA polymerase activity.