Dental caries status of preschool children in Hong Kong

OBJECTIVE

To describe the dental caries status of preschool children in Hong Kong and factors which affect their caries status.

DESIGN

658 preschool children aged 4 to 6 years from six randomly selected kindergartens in Hong Kong were surveyed in December 1997. A questionnaire to investigate possible explanatory variables for caries status was completed by their parents. Dental caries was diagnosed according to the criteria recommended by the World Health Organization (1997).

RESULT

Caries experience as measured by the mean number of decayed, missing and filled primary teeth (dmft) of the 4-, 5-, and 6-year-old children were found to be 0.9, 1.8, and 3.3 respectively. Overall, 61% of the children had a zero dmft score. Children born in Mainland China had a higher mean dmft score (4.6) than those born in Hong Kong (1.4). Statistically significant correlations were found between the children's dental caries status and their oral health practices as well as their socio-economic background. Parents' education level, dental knowledge and attitudes were also associated with the children's dental caries experience.

CONCLUSION

In general, the caries status of Hong Kong Chinese preschool children was similar to that of children in industrialised countries and was better than that of children in the nearby areas. However, special dental programmes should be made available to children from lower socio-economic classes and new immigrants from Mainland China because they are the high risk groups for caries in Hong Kong.

Correction factors for the INER-improved free-air ionization chambers calculated with the Monte Carlo method

Monte Carlo method was used to simulate the correction factors for electron loss and scattered photons for two improved cylindrical free-air ionization chambers (FACs) constructed at the Institute of Nuclear Energy Research (INER, Taiwan). The method is based on weighting correction factors for mono-energetic photons with X-ray spectra. The newly obtained correction factors for the medium-energy free-air chamber were compared with the current values, which were based on a least-squares fit to experimental data published in the NBS Handbook 64 [Wyckoff, H.O., Attix, F.H., 1969. Design of free-air ionization chambers. National Bureau Standards Handbook, No. 64. US Government Printing Office, Washington, DC, pp. 1-16; Chen, W.L., Su, S.H., Su, L.L., Hwang, W.S., 1999. Improved free-air ionization chamber for the measurement of X-rays. Metrologia 36, 19-24]. The comparison results showed the agreement between the Monte Carlo method and experimental data is within 0.22%. In addition, mono-energetic correction factors for the low-energy free-air chamber were calculated. Average correction factors were then derived for measured and theoretical X-ray spectra at 30-50 kVp. Although the measured and calculated spectra differ slightly, the resulting differences in the derived correction factors are less than 0.02%.

Outcome of root canal treatment using Thermafil and cold lateral condensation filling techniques

AIM

To evaluate the outcome of root canal treatment (RCT) using either Thermafil (TF) or lateral condensation (LC) as filling technique, and to compare the time required for the treatment when either filling technique was used.

METHODOLOGY

This study involved all patients attending the dental clinic of a university in Hong Kong who required primary, nonsurgical RCT. It was a prospective clinical trial involving 85 teeth in 79 patients aged 15-69 years (mean 48 +/- 12 years), which required root treatment and finally filling with either TF or LC by one of four dentists following a standard treatment protocol. The time used for the entire course of treatment was recorded. The treated teeth were examined both clinically and radiographically 3 years after the treatment by a single examiner who did not know their group assignment.

RESULTS

A total of 85 teeth from 79 patients were included in this study and 71 teeth from 64 patients were examined after 3 years. Thirty-four teeth were root filled with LC and 37 with TF. The overall attrition rate was 16% (14/85). There were 22 incisors and canines, 21 premolars and 28 molars for evaluation. Post-treatment disease with clinical symptoms and/or radiographic radiolucency was observed in seven teeth (21%) of the LC group and in seven teeth (19%) in the TF group. There was no statistically significant difference (P > 0.05) for the presence of disease between the two groups. It was found that irrespective of the filling method used, teeth later restored with extracoronal restorations had a lower association with disease than those receiving intracoronal restorations (7% vs. 30%; P = 0.037). RCT took, on average, 20 min less when TF was used for filling compared with LC (98 min vs. 78 min, P = 0.003).

CONCLUSIONS

Using TF or LC in the filling of root canals did not result in significant difference in the clinical treatment outcome. TF consumed significantly less time than LC. The type of postendodontic restoration had a significant association with the presence of post-treatment disease.

[Restriction polymorphism of mitochondrial DNA in Koreans and Mongolians]

Using the data on mitochondrial DNA (mtDNA) restriction polymorphism, the gene pools of Koreans (N = 164) and Mongolians (N = 48) were characterized. It was demonstrated that the gene pools were represented by the common set of mtDNA haplogroups of East Asian origin (M*, M7, M8a, M10, C, D4, G*, G2, A, B*, B5, F1, and N*). In addition to this set, mtDNA haplogroups D5 and Y were identified in Koreans while Mongolians possessed haplogroup Z. Only in Mongolians, a European component with the frequency of 10.4% and represented by the mtDNA types belonging to haplogroups K, U4, and N1, was identified. Phylogenetic and statistical analyses of the data on mtDNA variation in the populations of South Siberia, Central, and East Asia suggested the existence of interpopulation differentiation within these regions, the main role in which was played by the geographical and linguistic factors. Analysis of the pairwise F(ST) distances demonstrated close genetic similarity of Koreans to Northern Chinese, which in turn, were clearly different from Southern Chinese populations. Mongolians occupied an intermediate position between the ethnic groups of South Siberia and Central/East Asia.

Heart transplantation at Cheng Hsin General Hospital in Taiwan: 15-year experience

Heart transplantation (HTx) in Taiwan, which started in 1987, now includes more than 500 cases. From July 1988 to September 2003, we performed 215 cases of orthotopic HTx in 164 male and 51 female recipients of mean age of 47.3 +/- 14.3 years, (range 2.7 to 74.9 years). The leading etiologies were dilated cardiomyopathy (CMP), 68.5%; ischemic CMP, 20.2%; and valvular CMP, 4.2%. The actuarial survival rates at 1, 5, and 10 years are 88.3%, 77.1%, and 57.2%, respectively. We performed the first case of HTx in Asia after bridging for 14 days with an indigenous total artificial heart (TAH; the Phoenix-7 model); we performed the first case of infant HTx without blood transfusion and also the first case of autotransplantation of heart for repair of a left ventricular rupture after a mitral valve replacement. These cases were all successful with the longest surviving HTx recipient in Asia. We have used the biatrial anastomosis technique in all cases. We discovered familial CMP due to mitochondrial defects in two pediatric cases. Because of the scarcity of donor hearts, we have used size-mismatched hearts as well as suboptimal and hepatitis-positive donor hearts, all with satisfactory outcomes. Our experience has shown comparable results to Western programs, with efficacy and cost-effectiveness. We find the technique of biatrial anastomosis for orthotopic HTx to result in a low incidence of tricuspid regurgitation and conduction anomalies. The use of suboptimal and size-mismatched donor hearts is also promising.

Dose evaluation and measurement of the 188Re liquid-filled balloon in intravascular brachytherapy

We compared the Monte Carlo evaluation and GafChromic MD-55 film experimental measurement of 188Re liquid-filled balloons in intravascular brachytherapy using two phantoms of 6 mm vascular diameter, a phantom of 4 mm vascular diameter and a phantom of 3 mm vascular diameter. A dose-evaluation interface program was developed and was shown to be capable of quickly providing information such as the necessary 188Re source irradiation time to deliver a prescribed dose.

Esthetic designs of removable partial dentures

The increased emphasis on physical appearance in contemporary society has increased the demand for esthetic dental restorations. Although the success of implant dentistry has expanded the scope of esthetic fixed prostheses, many patients demand a removable partial denture (RPD) for health, anatomic, psychological, or financial reasons. Fabricating an esthetically pleasing RPD while avoiding the unsightly display associated with conventional clasp assemblies often presents a challenge to dentists. This article examines using lingual clasps, proximal undercuts (also known as rotational path insertion), and acetal resin clasps as simple and effective means of improving RPD esthetics.

Dental caries and periodontal status of 12-year-old school children in rural Qinghai, China

OBJECTIVES

To describe the dental caries and periodontal status of 12-year-old children in rural Qinghai and to compare the oral health status between the Han and ethnic minority children.

METHOD

Children aged 12-years in three primary schools in Hexi Townships, Guide County, Hainan Tibetan Autonomous State, Qinghai Province, China, were invited to participate in the survey conducted during July 2001. Each child was interviewed and clinically examined in the schools, using portable equipment. World Health Organization (WHO) examination procedures and diagnostic criteria were used. SPSS 11.0 was used for data compilation and statistical analysis.

RESULTS

All 196 12-year-olds (118 Han and 78 from ethnic minorities, i.e. Muslims and Tibetans) were surveyed. 48% of the children reported never brushing their teeth, while 12% brushed only every 2-3 days. Over ninety per cent (n=182) of the children had never visited a dentist. The DMFT scores in Han and in minority groups were found to be 0.12 and 0.23 respectively. A larger proportion of children in Han group (94%) had no caries experience (DMFT = 0) than that of Muslim and Tibetan (82%) groups (p<0.01). None of the children had healthy gingiva (i.e. highest CPI score=0) and 85% had calculus.

CONCLUSION

The prevalence of caries experience in Han children is significantly lower than that in Muslim and Tibetan children in rural Qinghai. Dental caries and caries treatment needs of Han and minority rural schoolchildren in Qinghai are low but their periodontal health status is unsatisfactory. Basic dental health care and preventive education for the children in this part of China is needed.

Effectiveness of silver diamine fluoride and sodium fluoride varnish in arresting dentin caries in Chinese pre-school children

Untreated dental caries in Chinese pre-school children is common. This prospective controlled clinical trial investigated the effectiveness of topical fluoride applications in arresting dentin caries. Three hundred seventy-five children, aged 3-5 years, with carious upper anterior teeth were divided into five groups. Children in the first and second groups received annual applications of silver diamine fluoride solution (44,800 ppm F). Sodium fluoride varnish (22,600 ppm F) was applied every three months to the lesions of children in the third and fourth groups. For children in the first and third groups, soft carious tissues were removed prior to fluoride application. The fifth group was the control. Three hundred eight children were followed for 30 months. The respective mean numbers of arrested carious tooth surfaces in the five groups were 2.5, 2.8, 1.5, 1.5, and 1.3 (p < 0.001). Silver diamine fluoride was found to be effective in arresting dentin caries in primary anterior teeth in pre-school children.

Fee-paying systems and service patterns in a Hong Kong dental clinic

OBJECTIVE

This study aimed to describe and compare patients' consumption of dental services and dentists' productivity in a university campus clinic before and after changing from a time-based to an item-based fee-paying system.

METHOD

Data were collected from the University of Hong Kong dental clinic which serves all university students and staff. A time-based fee-paying system had been in use up to February 1999 when it was switched to an item-based system. Computerised records of all patients in two 1-year periods starting from February 1996 and February 1999 were analysed.

RESULTS

The percentages of eligible users who attended the University dental clinic were similar in the two study periods (30% in 96/97 vs 29% in 99/00). However, on average, patients consumed more dental service items in a year after the switch in fee-paying system (3.2 vs 4.1). There was also an increase in the mean number of dental service items provided by a dentist per working week after the change in fee-paying system (71.5 vs 99.4).

CONCLUSION

On switching from a time-based to an item-based fee-paying system, dentists in the UHS dental clinic became more productive and the consumption of dental services per patient also increased.

A community-based caries control program for pre-school children using topical fluorides: 18-month results

Dental caries in Chinese pre-school children is common, and restorative treatment is not readily available. This prospective controlled clinical trial investigated the effectiveness of topical fluoride applications in arresting dentin caries. We divided 375 children (aged 3-5 yrs) with carious upper anterior teeth into five groups. Children in the first and second groups received annual applications of silver diamine fluoride solution (44,800 ppm F). NaF varnish (22,600 ppm F) was applied every three months onto the lesions of children in the third and fourth groups. For children in the first and third groups, soft carious tissues were removed prior to fluoride application. The fifth group was the control. We followed 341 children for 18 months. The mean numbers of new caries surfaces in the five groups were 0.4, 0.4, 0.8, 0.6, and 1.2, respectively (p = 0.001). The respective mean numbers of arrested carious tooth surfaces were 2.8, 3.0, 1.7, 1.5, and 1.0 (p < 0.001).

Linkage and mutation analysis in two Taiwanese families with long QT syndrome

Long QT syndrome (LQT) is a cardiovascular disorder causing syncope and sudden death from arrhythmias. Mutations in KCNQ1, KCNH2, KCNE1, KCNE2, and SCN5A genes encoding cardiac potassium and sodium ion channels cause LQT. Two Taiwanese LQT families were screened for mutations in these ion channel genes. In family H87, the diagnosis was made in the 25-year-old female proband and six family members based on recurrent syncope and/or a prolonged QT interval. Genotyping revealed a novel nonsense mutation, R744X (C to T transition in codon 744), in the KCNH2 potassium channel gene, resulting in truncation of the putative cyclic nucleotide-binding domain and C-terminal region of the HERG K(+)-channel in all affected family members. The mutation was confirmed by DdeI endonuclease digestion of the DNA from each family member. The 26-year-old female proband in family L89 developed repeated syncope with QTc of 0.61 seconds. After linkage and mutation analysis, the syndrome in this family was associated with a novel KCNQ1 missense mutation, T309I, causing the substitution of a threonine residue at position 309, in the pore region of the KvLQT1 K(+)-channel, with an isoleucine. By Tsp45I restriction analysis, the mutation was noted in the proband and the proband's asymptomatic brother, but was not detected in 100 unrelated normal individuals. Identification of a mutation has clinical implications for presymptomatic diagnosis and therapy.

Monitoring patient satisfaction with university dental services under two fee-paying systems

AIMS

The aim of this survey was to study patients' satisfaction with the dental service of a university in Hong Kong under a recently introduced item-based fee-paying system and reasons for non-attendance at the clinic; and to compare results of the present survey with that of a similar survey of the same dental service under a time-based fee-paying system in 1996.

METHOD

A modified Dental Satisfaction Questionnaire was distributed to a random sample of students (n=194) in their lecture rooms and they were asked to complete the questionnaire on the spot. The same questionnaire was sent to a random sample of staff and their spouses (n=207) by mail.

RESULTS

Dental Satisfaction Index (DSI) scores calculated from the returned questionnaires were 66 for students and 70 for staff and their spouses. Compared to the scores in 1996, there was no significant difference for that of the students (DSI=65 in 1996) but there was a significant improvement in that of the staff and their spouses (DSI=66 in 1996). Moreover, in the present survey, "busy/no time" and "no perceived dental problem" were the major reasons for non-attendance, in contrast to "long waiting time for an appointment" in the 1996 survey, were the major reasons for non-attendance.

CONCLUSION

The recent attempts by the University Dental Clinic to shorten patient waiting time and the change in fee-paying system might have improved the patients' satisfaction with the service.

Large drug resistance virulence plasmids of clinical isolates of Salmonella enterica serovar Choleraesuis

Salmonella enterica serovar Choleraesuis generally causes systemic human salmonellosis without diarrhea, and therefore, antimicrobial treatment is essential for such patients. The drug resistance information on this organism is thus of high value. Serovar Choleraesuis usually harbors a virulence plasmid (pSCV) of 50 kb in size. Of the 16 clinical isolates identified to be serovar Choleraesuis, all except one harbored a pSCV and seven of them carried a pSCV of more than 125 kb in size. A pSCV was defined as a plasmid carrying spvC and characteristic deletions detected by PCR and by DNA-DNA hybridization (for the former criterion). The results of PCR, restriction fragment profiles, and Southern DNA-DNA hybridizations of the profiles all indicated that such larger pSCVs were derived from the 50-kb plasmid recombined with non-pSCVs found in some clinical isolates. Fifteen of the 17 strains, including a laboratory strain, were then tested for drug resistance against 16 antibiotics with E-test and the dilution method. The laboratory strain, which harbored a 50-kb pSCV and a 6-kb non-pSCV, was resistant only to sulfonamides (SUL), and its resistance gene, sulII, checked with PCR and DNA-DNA hybridization, was located on the 6-kb non-pSCV. All 14 clinical strains were resistant to multiple drugs. Of the 14, 7 were resistant to SUL, and the resistance gene was located on a plasmid. The sulII gene, but not bla(TEM-1), was carried only on the 6-kb non-pSCV. Of the remaining six large plasmids, three of 90 kb, two of 136 kb, and one of 140 kb, the last three were pSCVs and carried the other SUL gene (sulI) and the bla(TEM-1) gene. The six strains were also resistant to trimethoprim-sulfamethoxazole. None of the 50-kb pSCVs carried resistance genes. These drug resistance genes on the large pSCVs were apparently also acquired through recombination.

Prognostic factors of hyperglycemic hyperosmolar nonketotic state

BACKGROUND

To delineate the prognostic factors of patients suffering from hyperglycemic hyperosmolar nonketotic state (HHNK) in Taiwan.

METHODS

We reviewed the charts of patients who had been admitted to the Division of Endocrinology and Metabolism of Kaohsiung Veterans General Hospital from 1992 to 1998 due to HHNK. General and clinical data were collected. The influential factors for prognosis were determined.

RESULTS

One hundred and nineteen patients fulfilling the criteria of HHNK were included in our study. The mean age was 67.8 +/- 11.7 years with male predominance. Twenty-nine patients died which produced a fatality rate of 24.4%. Eighty-six (72.3%) cases occurred in patients with known diabetic history, while another thirty-three (27.7%) occurred in patients with no diabetic history. Most patients received oral antidiabetic drugs before HHNK episodes. The patients who died had shorter length of inpatient stay than did survivors. The leading precipitating factor was infection (57.1%), followed by poor compliance of medication (21.0%) and undiagnosed diabetes (10.9%). Fifty patients (42%) had a history of stroke. The risk factors for death included precipitation of HHNK by infection and low Glasgow coma scale (GCS) on admission. Old age itself did not contribute to death. Severity of hyperglycemia or hyperosmolarity was also not an important prognostic factor. Multiple logistic regression revealed that low GCS on admission was the most influential factor of leading to death. Most of the patients who died did so due to underlying precipitating factors.

CONCLUSIONS

Neither age nor osmolarity, but underlying precipitating factors and state of consciousness were the most influential factors affecting the prognosis of HHNK.

1.55-mum and infrared-band photoresponsivity of a Schottky barrier porous silicon photodetector

We have investigated the spectral responsivity of porous silicon Schottky barrier photodetectors in the wavelength range 0.4-1.7 mum . The photodetectors show strong photoresponsivity in both the visible and the infrared bands, especially at 1.55 mum . The photocurrent can reach 1.8 mA at a reverse bias of 6 V under illumination by a 1.55-mum , 10-mW laser diode. The corresponding quantum efficiency is 14.4%.

Molecular cloning, modeling, and localization of rat type 10 17beta-hydroxysteroid dehydrogenase

Rat and mouse complementary DNAs of type 10 17beta-hydroxysteroid dehydrogenase were cloned and sequenced. The mouse cDNA clone's sequence corrected the previously published nucleotide and amino acid sequence of mouse endoplasmic reticulum-associated beta-amyloid-binding protein. A subunit of the rat enzyme consists of 261 amino acid residues with a calculated molecular mass of 27250 Da. Compared with its human counterpart, rat 17betaHSD type 10 shows 88% identity. Mouse 17betaHSD type 10 is composed of 261 amino acid residues with a calculated molecular mass of 27274 Da. There is 95% identity between the two rodent enzymes. A stereostructure model of rat 17betaHSD type 10 was constructed based on its amino acid sequence. Similar to human type 10 17betaHSD, the rodent enzymes also displayed relatively higher 3alphaHSD activity than 17betaHSD activity. Intracellular localization of rat 17betaHSD type 10 has been determined by subcellular fractionation and confocal microscopy studies. The results unequivocally establish that this is a nuclear gene-encoded mitochondrial enzyme, and that this 17betaHSD is not associated with the endoplasmic reticulum. The unique location distinguishes type 10 from other types of 17beta-hydroxysteroid dehydrogenases.

Treatment of early childhood caries: a review and case report

Caries in infants and young children long has been recognized as a clinical entity and described variously as nursing caries, nursing bottle syndrome and so on. Although prolonged use of the baby bottle is believed to be associated with increased risk of caries, use of the bottle may not be the most important factor in caries development. The term early childhood caries (ECC) has been suggested because it more closely reflects the multifactorial etiologic process involved in the disease. A case of ECC treated in a general dental practice and managed under local anesthesia is reported.

The bioavailability of beta-carotene in stir- or deep-fried vegetables in men determined by measuring the serum response to a single ingestion

To evaluate the bioavailability of beta-carotene from plant foods, the serum beta-carotene response to a single ingestion of various beta-carotene sources was determined in 10 healthy men. Tested beta-carotene sources included stir-fried shredded carrot, stir-fried water convolvulus leaves, deep-fried sweet potato ball, purified beta-carotene in a capsule (beadlets) and beadlets with beta-carotene free oriental radish (beadlets + radish). The maximal change in serum beta-carotene concentration occurred at 24 or 32 h post ingestion. This response to beadlets was significantly higher than that to the other four tested beta-carotene sources (P < 0.05). The maximal serum response to beadlets + radish was also significantly higher than that to the three food beta-carotene sources (P < 0.05). The maximal serum response to sweet potato was significantly higher than that to water convolvulus leaves (P < 0. 05). The bioavailability relative to beta-carotene beadlets was calculated by dividing the maximal change in serum concentration to each test meal of each subject by his own serum maximal change in response to beadlets. Accordingly, the bioavailability was 65% for beadlets + radish, 33% for carrots, 26% for water convolvulus leaves and 37% for sweet potatoes. Concurrent ingestion of oriental radish reduced the bioavailability of beadlets to two-thirds of its original value, which partially accounted for the difference between the bioavailability of beadlets and natural foods. The relative bioavailability of beta-carotene from stir-fried and deep-fried vegetables was about one-third to one-fourth that of the purified beta-carotene beadlets. These bioavailabilities are higher than previously reported values.

Small cell carcinoma of the gallbladder: report of two cases

Two Taiwanese patients with gallbladder small cell carcinoma are reported. One is a 79 year-old male, the other, a 86 year-old female. They both presented with the symptom/signs of acute cholecystitis and underwent cholecystectomy. An intramural mass in the gallbladder neck region was found in the first patient, while the second patient had a transmural indurated tumor in the gallbladder body with extension to the neck region. Characteristic histological and immunohistochemical features of small cell carcinoma were present in both, and electron dense neurosecretory granules were identified in the second. To our knowledge, the second patient is the oldest ever reported. The first patient received chemotherapy directed toward the initial erroneous diagnosis of non-Hodgkin s lymphoma and developed liver metastasis in two months. The second patient did not receive chemotherapy due to her poor general condition and local recurrence occurred in six weeks. Both passed away three and five months after surgery, respectively.

Romano-Ward long QT syndrome: identification of a HERG mutation in a Taiwanese kindred

Romano-Ward syndrome is an autosomal dominant long-QT syndrome (LQTS) that predisposes affected individuals to sudden death from tachyarrhythmias. We investigated the molecular basis of LQTS in a Taiwanese kindred. Clinical and genetic analyses revealed that a mutation was linked to the human ether-a-go-go-related gene (HERG). The coding sequences and exon-intron borders of HERG were amplified by means of polymerase chain reaction and subjected to single-strand conformation polymorphism (SSCP) analysis. An exon with an aberrant SSCP pattern was cloned and sequenced to study the molecular lesion. A C-->T transition in codon 614, leading to substitution of a valine for an alanine residue in the pore region of the HERG protein, was identified. Analysis with Bsp12861 endonuclease digestion showed the mutation to be present in all affected family members. Given that an unaffected paternal uncle had inherited the same allele from the grandfather as the proband's father, a de novo mutation had apparently occurred in the father and was transmitted to his offspring. In addition to offering presymptomatic genetic diagnosis, identification of the disease-causing mutation may suggest new therapeutic approaches for treatment and prevention of this cardiovascular disease.

Detection and identification of Mycobacterium tuberculosis by nested PCR assays in cerebrospinal fluid samples from patients with suspected tuberculous meningitis

We used the nested polymerase chain reaction (PCR) assays developed previously to detect and identify Mycobacterium tuberculosis (M. tuberculosis) in the cerebrospinal fluid (CSF) samples from patients with suspected tuberculous meningitis and non-tuberculous patients. Our nested PCR assays target the multi-copy IS6110 insertion element and the single-copy mtp40 genomic DNA of M. tuberculosis. These assays, when used in combination, allowed us to detect a very low number of M. tuberculosis in the CSF samples, which otherwise would be undetectable by the culture method, and to distinguish M. tuberculosis from M. bovis. We applied these nested PCR assays to analyze eleven CSF samples. Among these, five of them were from patients with suspected tuberculous meningitis but all except one were culture negative. Our results of PCR assays show that three of these five are M. tuberculosis positive, one of which is M. bovis positive, and only one is M. tuberculosis negative. The other six CSF samples were from the clinically diagnosed non-tuberculous patients. Surprisingly, two of these so called non-tuberculous patients, a subarachnoid hemorrhage (SAH) and the syndrome of inappropriate antidiuretic hormone secretion (SIADH), were shown M. tuberculosis positive. This finding supports a long-standing argument that tuberculous meningitis is one of the causes of these neurological diseases. These nested PCR assays thus provide the neurologists with an important adjunct, in addition to the patient's clinical presentation and laboratory data, for the diagnosis of tuberculous meningitis.

Determination of the sensitivity and specificity of PCR assays using different target dnas for the detection of Mycobacterium tuberculosis

To establish a sensitive, specific and reproducible PCR assay for the detection of Mycobacterium tuberculosis, we evaluated three target DNAs: IS6110, 65 kDa heat shock protein gene; and mtp40 genomic fragment. We purified genomic DNA from 15 mycobacterial strains including four M. tuberculosis isolates, four M. bovis BCG isolates, and one of each for M. fortuitum, M. avium, M. intracellulare, M. szulgai, M. scrofulaceum, M. chelonei, and M. gordonae from the culture and used them as the template DNA. We studied 3 primer sets for IS6110, 2 primer sets for 65 kDa, and 3 primer sets for mtp40. Depending on the assay, these primer sets were used in the single-step PCR and/or nested PCR. The PCR assay targeting the 65 kDa protein gene could detect all of the tested mycobacterial strains, whereas targeting the IS6110 sequence resulted in detection of only M. tuberculosis and M. bovis BCG. Furthermore, targeting the mtp40 genomic fragment could be used to distinguish M. tuberculosis from M. bovis BCG. Using a nested PCR assay with primer sets specifically targeting the IS6110 or 65 kDa, we have been able to detect single copy M. tuberculosis genomic DNA. When the mtp40 genomic fragment was used as the target DNA, the sensitivity of detection was 10 copies of M. tuberculosis genomic DNA. This assay was demonstrated to have good sensitivity and specificity for detection and discrimination of mycobacterial species, and could be used in analyzing the clinical samples with low copy number infections such as the cerebrospinal fluid from the patient with tuberculous meningitis.

Patients' satisfaction with dental services provided by a university in Hong Kong

This study was a consumer evaluation of the dental care services provided by a university dental clinic in Hong Kong which provides dental care to all university students and staff and their dependents. The objectives of this study were to study the consumers' satisfaction with the dental services; to identify their reasons for not using the dental services; and to compare the opinions of the students with those of the university staff and their spouses. A total of 140 students and 180 staff and their spouses were randomly selected for this study. The response rates were 100 per cent for students and 77 per cent for staff and their spouses. Results showed that both groups of respondents were satisfied with the quality of dental services provided by the university dental clinic. However, they were not satisfied with the long waiting time for an appointment. Students who had not attended the university dental clinic commonly stated that they were busy and had no time for a dental visit. Conversely, many staff and their spouses did not seek care from the university dental clinic because they thought that the fees were high. Although the overall Dental Satisfaction Index (DSI) scores for the students (64.5) and staff and their spouses (65.1) were similar, there were differences in the aspects of the services with which the two group were satisfied or dissatisfied. Thus if the university dental clinic wants to implement changes so as to improve consumer satisfaction and utilisation, a careful analysis of the specific opinions of its various consumer groups is required.