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Biomedical subjects

T Loh

Publications and source records attributed to T Loh.

16 recordsLinked to original sources
PubMed1997

Perceived masticatory function among elderly people.

This study investigated the status and associations of perceived chewing ability of a group of 891 elderly people, aged 55-91 years (average age 66 years). The majority of subjects (69%) considered that they could chew well. Only 9% reported poor chewing ability. This judgement was not associated with age. More men (11%) than women (6%) had reported poor chewing ability. Subjects with better perceived general and craniomandibular health reported better chewing ability. However, although related to permanent tooth loss, the perception of chewing ability was not seemingly associated with prosthetic rehabilitation. All elderly subjects with complete dental arches had no complaints of perceived chewing difficulty. Freedom from symptoms of craniomandibular pain when chewing, bilateral chewing activity and a wide choice of food range or textures were associated with favourably perceived chewing ability. This study identifies several suitable criteria for judging masticatory function and suggests that these may be used to complement chewing ability as an alternative measure of masticatory performance. These criteria are applicable to the elderly person, in particular, and warrant adequate clinical application.

Adaptation, Psychological↗
PubMed1996

Oral health of Singapore adults.

In a study conducted by the Dental Division of the Ministry of Health in 1992, 3157 Singapore adults aged 20 to 65 years and over were interviewed on their knowledge, attitude and practice of dental care and given an examination. About 66% indicated they required dental treatment. Utilisation of dental services was low with 39% visiting the dentist at least once in 2 years. About 72% brushed their teeth morning and night. The dental examination showed that 79.2% had calculus, 92% needed prophylaxis and oral hygiene instruction and only 0.2% needed complex periodontal treatment. A large proportion (96.6%) of the sample was dentate. The mean DMFT was 10.7 and the mean number of decayed root for the dentate population was 0.2. The age-group 65 years and over had the highest percentage (63.6%) of persons wearing dentures and the age group 50-54 years had the highest percentage (54.2%) requiring dentures. This study has shown that oral health promotion for home and professional care should be stressed to the adult population, particularly the older age groups.

Adolescent↗
PubMed1996

Thirty-eight years of water fluoridation--the Singapore scenario.

The high caries rate in Singapore school children was of great concern to dental administrators. Remedial measures alone were not the solution. The success of water fluoridation in Grand Rapids, USA and in Brantford, Canada in reducing dental caries in children in the early 1950s prompted Singapore to introduce fluoride into its drinking water. Singapore is the first country in Asia to institute a comprehensive fluoridation programme which covers 100 per cent of the population. The water was fluoridated at 0.7 ppm fluoride using sodium silicofluoride. The ten year study on the effects of water fluoridation in Singapore showed a decrease in caries prevalence in the children. In the permanent dentition the reduction was 52.3 per cent for Chinese and 31 per cent for Malays in the 7 to 9 year old age group. A similar trend was observed in the mixed dentition in which the decrease was 32.5 per cent for Chinese and 30.6 per cent for Malays. Because of the availability and use of other fluoride products, dental fluorosis was observed in children in later years. Although the decline in dental caries after 10 years of water fluoridation was not comparable to those achieved in other countries, this study further documents water fluoridation as the most cost-effective public health measure for the prevention of dental caries.

Adolescent↗
PubMed1995

Symptoms of craniomandibular disorder among elderly people.

This study investigated the subjective symptoms of craniomandibular disorder and the restriction in maximal mandibular opening of 891 elderly Singaporean citizens. A distribution of 22% of subjects (20% of the women and 26% of the men) reported subjective symptoms of craniomandibular disorders. The most common single symptom reported was occasional to frequent clicking sounds from the temporomandibular joints (in 15% of subjects). The other single symptoms were reported only occasionally in 2-6% of subjects. Nineteen per cent of the subjects had some restriction in maximal interincisal opening (30-39 mm) and about 1% of subjects were severely restricted in maximal opening (less than 30 mm). Subjectively evaluated limitation of wide mandibular opening was recorded for only 2% of the subjects. Background factors included general musculo-skeletal problems (54%), perceived fair to poor general health (29%), headaches (33%), work-related stress (24%), oral parafunctional clenching (4%) and grinding activity (4%). This paper confirms earlier reports that the subjective signs and symptoms of craniomandibular disorder tend to diminish in elderly people.

Age Factors↗
PubMed1995

Relation between incisal overjet and traumatic injury: a case control study.

Most previous studies have shown the prevalence of traumatic dental injuries in anterior teeth to increase with increasing overjet. This study identified 36 Singapore schoolchildren, age 7-18 years, from a clinic population of 11,179, who had suffered dental trauma while playing contact or collision sports. A case control group of 36 children, matched for age, sex, race and sporting activities, but who had not suffered dental trauma, was selected from the same clinic population. Both groups were examined and the nature of injuries received, together with overjet measured to the nearest 0.5 mm were determined. The mean overjet for the trauma group was 3.42 +/- 1.45 mm and for the injured group 3.42 +/- 1.33 mm. These means were not statistically different (p = 1.00), neither did the distribution of overjet between the groups differ. These data were not in accord with the majority of studies correlating incisal overjet and dental trauma, and they suggested that overjet was not a positive correlate with traumatic dental injury in Singapore schoolchildren.

Adolescent↗
PubMed1995

A survey of tooth injury experience and attitudes to prevention in a group of Singapore schoolboys.

A survey of 246 boys aged 12-17 years (mean 13.8 years) determined the sports played, dental injury experience, knowledge and usage of and attitudes towards mouthguard wearing. Most played basketball and soccer. Twenty-one suffered 1 injury episode, 7-2 and 10-3 or more tooth injuries. Twenty-six subluxations, 19 fractures and 1 avulsion were reported. The sports with the highest prevalence of dental injury were boxing and wrestling (33%), soccer (20%), and basketball (19%). While 144 (56%) of boys knew about mouthguards, none wore one. Only 64 (25%) would wear a mouthguard if given one. Most dental injuries were minor, but four high-risk sports (> 19% injury prevalence) would justify preventive measures, including education for injury prevention and encouragement of mouthguard use.

Adolescent↗
PubMed1994

Cathepsin G: localization in human cerebral cortex and generation of amyloidogenic fragments from the beta-amyloid precursor protein.

Amyloid deposits in Alzheimer's disease, Down's syndrome and aged brain are composed largely of A beta protein, which is generated by proteolytic processing of beta-amyloid precursor protein. Proteases responsible for liberating the A beta protein from the precursor have not yet been identified. Here, we examined the ability of cathepsin G, a chymotrypsin-like protease, to cleave two protease substrates: (i) a fluorogenic hexapeptide, whose sequence spans the cleavage site in the precursor for generating the A beta NH2-terminus, and (ii) recombinant human beta-amyloid precursor protein purified from a baculovirus expression system. Unlike two other members of the chymotrypsin family, cathepsin G readily degraded the hexapeptide. Furthermore, cathepsin G cleaved the beta-amyloid precursor protein to generate several breakdown products, including a prominent 11,500 mol. wt fragment immunoreactive with antibodies directed against the COOH-terminus of the protein. This COOH-terminal fragment co-migrated using two-dimensional isoelectric focusing/sodium dodecyl sulfate-polyacrylamide gel electrophoresis with C-100, a recombinant COOH-terminal segment of the beta-amyloid precursor, whose NH2-terminus is one residue upstream of the NH2-terminus of the A beta domain. We also examined the localization of cathepsin G in human brain. The distribution of cathepsin G-containing cells was examined by immunohistochemistry in the temporal cortex of both Alzheimer's and aged control samples. Cathepsin G-like immunoreactivity was contained specifically within neutrophils. As visualized by double-labeling with antibodies to cathepsin G and Factor VIII, neutrophils were most frequently found within meningeal or cortical blood vessels. In addition, occasional neutrophils could be identified without an apparent vascular surround, in the brain parenchyma. By simultaneous labeling with antibodies to cathepsin G and A beta protein, neutrophils were also sometimes found associated with both parenchymal and vessel amyloid deposits; however, these associations were rare. These findings indicate that cathepsin G is capable of cleaving the beta-amyloid precursor protein to liberate the free NH2-terminus of the A beta protein and may have access to areas where this material is deposited in Alzheimer's disease. However, since there is no physical association between neutrophils and deposited amyloid and no increase in the number of neutrophils in an Alzheimer's brain, cathepsin G seems to be an unlikely mediator of amyloid deposition in this disease.

Alzheimer Disease↗
PubMed1993

Processing of the beta-amyloid precursor. Multiple proteases generate and degrade potentially amyloidogenic fragments.

Proteolytic processing of the beta-amyloid precursor proteins (APP) is required for release of the beta/A4 protein and its deposition into the amyloid plaques characteristic of aging and Alzheimer's disease. We have examined the involvement of acidic intracellular compartments in APP processing in cultured human cells. The use of acidotropic agents and inhibitors to a specific class of lysosomal protease, coupled with metabolic labeling and immunoprecipitation, revealed that APP is degraded within an acidic compartment to produce at least 12 COOH-terminal fragments. Nine likely contain the entire beta/A4 domain and, therefore, are potentially amyloidogenic. Treatment with E64 or Z-Phe-Ala-CHN2 irreversibly blocked activities of the lysosomal cysteine proteases cathepsins B and L but did not inhibit the lysosomal aspartic protease cathepsin D and did not alter the production of potentially amyloidogenic fragments. Instead, the inhibitors prevented further degradation of the fragments. Thus, large numbers of potentially amyloidogenic fragments of APP are routinely generated in an acidic compartment by noncysteine proteases and then are eliminated within lysosomes by cysteine proteases. Immunoblot and immunohistochemical analyses confirmed that chronic cysteine protease inhibition leads to accumulation of potentially amyloidogenic APP fragments in lysosomes. The results provide further support for the hypothesis that an acidic compartment may be involved in amyloid formation and begin to define the proteolytic events that may be important for amyloidogenesis.

Amyloid beta-Protein Precursor↗
PubMed1993

Singapore dentists' knowledge, advocacy and utilisation of mouthguards.

A questionnaire was distributed to Singapore Registered Dental Practitioners, seeking demographic details, knowledge of mouthguards in preventing dental injury during contact sport, current attitudes to advice and provision to at-risk patients. 636 questionnaires were posted and 226 valid replies were received. Most dentists believed that mouthguards reduced the prevalence of dental injury in contact sports. Undergraduate education was the primary source of dentists' knowledge. Seventy-four per cent of respondents actively recommended mouthguards, but only 26 per cent made one or more in 1992. Only 3 dentists made more than 10. Twenty-eight per cent were comfortable with their knowledge in this area, and 76 per cent would be willing to assist a public awareness campaign.

Athletic Injuries↗
PubMed1993

Mouthguards: an easy-to-fabricate element of practice preventive programmes.

Mouthguards reduce the prevalence of dental injuries in contact sports. All types are effective, but those which are closely adapted to the teeth are the best retained, most comfortable, and therefore best accepted by sports people. Closely fitting mouthguards can be directly adapted in the mouth or laboratory-made on a stone model of the dental arch. The mouth-formed types can be fitted without professional supervision, but the procedure is often more successful if undertaken or supervised by a dental professional. The mouth forming procedure is quick and involves little material cost compared to the laboratory-made type. These savings can be passed on to patients in the form of lower fees which should encourage the widespread acceptance of mouthguards as a cost-effective preventive measure. Professionally fitted laboratory-made mouthguards are particularly suitable for high risk activities such as boxing, where more specialised protection such as a bimaxillary guard is indicated.

Athletic Injuries↗
PubMed1992

Incidence and management of middle ear effusion in cleft palate patients.

For a complete overall rehabilitation of cleft palate patients a multi-disciplinary approach should be adopted. Plastic and Head and Neck Surgeons in whom most of the treatment are entrusted should be concerned not only at achieving palatal function and cosmetic acceptability but also the various other problems associated with cleft palate especially hearing loss. In this study, 66 patients with repaired and unrepaired cleft palates were examined for the presence of hearing loss due to middle ear effusion. The incidence of middle ear effusion was high (57.6%). It was also found that only eight of these patients (12.1%) ever complained of hearing loss or any associated symptoms and repair of the cleft palate did not influence the incidence of middle ear effusion. As such, screening should be done in all cleft palates and otolaryngologists should therefore play an important role in the multi-disciplinary team which should comprise the paediatrician, plastic surgeon, speech therapist, orthodontist and dental specialist.

Child↗
PubMed1991

Rapid postmenopausal loss of total body and regional bone mass in normal southern Chinese females in Hong Kong.

Osteoporosis is a major health problem in Hong Kong, affecting about 200,000 patients among a population of 6 million. To evaluate the rate of bone loss and determinants of low bone mass among the Southern Chinese, we measured the total body and regional bone mass with the XR-26 dual-energy X-ray absorptiometry in 90 normal females. The results show that the total and regional bone densities were stable before menopause, with a change of around 0.5% every year. After menopause, a rapid loss is evident for total body and regional bone mass. The rate of bone loss varies from 1.2% for the pelvis to 3.1% for the Ward's triangle per year. Thus, by the age of 70, most Southern Chinese females would have lost at least 25% of their bone. Age, body weight, and skeletal area are important determinants for the total body bone mass. Bone densities in weight-bearing regions, including hip, pelvis, spine and legs correlate strongly with each other (r = 0.68, P less than 0.001). Correlation is poor among unrelated regions, such as between head and arms (r = 0.39, P greater than 0.5). To conclude, normal Chinese women in Hong Kong lose bone rapidly after menopause at a rate of about 2% per year. This may account for the major incidence of osteoporosis-related complications in Hong Kong.

Absorptiometry, Photon↗
PubMed1977

Acupuncture--effect on normal subjects.

The effect of acupuncture analgesia on pain threshold was assessed in a group of 60 healthy volunteers. On the average a 60% elevation of the pain threshold was achieved. This effect was seen bilaterally with unilateral acupuncture stimulation. There was no significant difference in the effect produced by three widely separate sites of acupuncture stimulation. The possibility of an additive effect when two sites were simultaneously stimulated was not confirmed in our limited study. Evidence is presented that sensory nerve fibre stimulation may be the basic primary requirement of successful acupuncture analgesia.

Acupuncture Therapy↗
PubMedDate not supplied

Mutant and native human beta-amyloid precursor proteins in transgenic mouse brain.

Human beta-amyloid precursor protein (beta APP) has been targeted to transgenic neurons using synapsin I promoter-based chimeric transgenes. Native human beta APP was introduced as well as beta APP containing mutations genetically linked to familial Alzheimer's disease (AD) and to hereditary cerebral hemorrhage with amyloidosis-Dutch type. In mouse brain, human beta APP RNA was up to 60% as abundant as total endogenous beta APP RNA. Human beta APP gene expression was most abundant in the CA subfields of the hippocampus and in the piriform cortex. Correct processing of human beta APP at the beta-secretase cleavage site was demonstrated in transgenic mouse brains. Despite a 40% increase in total beta APP immunoreactivity in lines expressing mutant human beta APP, no evidence of amyloid deposition was found in brains of mice up to 14 months in age. Higher levels of mutant human beta APP, increased age, or other factors may be necessary to elicit beta-amyloid-related neuropathologies in the rodent brain.

Amyloid beta-Protein Precursor↗