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Biomedical subjects

G Ong

Publications and source records attributed to G Ong.

At least 37 records · Page 2Linked to original sources
PubMed1996

Use of the endotracheal tube as a pharyngeal airway.

An animal study was conducted to determine whether an endotracheal tube placed above the vocal cords in the pharynx can be used for ventilation. Four dogs undergoing general anesthesia were ventilated through an endotracheal tube placed in the oropharynx with the remainder of the airway occluded. Ventilation was performed for 3 of every 5 minutes during a total period of 25 minutes. Arterial PCO2 was compared in sequential samples alternating apnea and pharyngeal ventilation. Ventilation via the pharyngeal tube significantly reduced the arterial PCO2 from 48.8 mm Hg (SD 16) during apnea to 30.1 mm Hg (SD 10.9). Repeated measures ANOVAF = 8.2, P < .001. All PCO2 levels during ventilation were in or below the normal range of 34 to 46. Provided that the mouth and nose can be sealed, an endotracheal tube placed in the pharynx above the cords allows for adequate ventilation.

Analysis of Variance↗
PubMed1996

Periodontal reasons for tooth loss in an Asian population.

This study analysed data on periodontal reasons for tooth extractions, obtained from 52 dentists practising general dentistry in Singapore. The results revealed that, out of 2172 teeth extracted from 1276 patients, 35.8% were lost due to periodontal disease and 35.4% due to caries. Extraction due to periodontal problems increased with age, were more conspicuous in the Indian ethnic group and were frequently associated with pocketing and tooth mobility.

Adolescent↗
PubMed1996

A survey of reasons for extraction of permanent teeth in Singapore.

A survey was carried out to determine the reasons for tooth extractions of permanent teeth in Singapore. Data were obtained from 52 dentists practising general dentistry over a period of 12 months. At the end of the 12-month period, data were collected from 1276 patients, from whom a total 272 teeth were extracted. In this population group, the results showed that the percentage of teeth extracted due to periodontal reasons and caries were about the same, that is 35.8% and 35.4%, respectively. There was an increase in teeth extracted due to periodontal reasons with age. In patients above 40 yr, an average of 76% of teeth were lost due to periodontal reasons. An average of 26.7% of teeth were lost due to periodontal reasons in patients under 40 yr old. However, the trend for loss of teeth due to caries is reversed. Posterior teeth were more frequently extract compared to anterior teeth. Third molars accounted for 24.7% of all extractions carried out, whilst central incisors were 8.0% of all extractions. Molars were often lost due to caries and lower anterior teeth were most frequently lost due to periodontal reasons. The results of this study did not demonstrate one predominant reason for extraction. Both caries and periodontal reasons were equally common causes of tooth extraction.

Adolescent↗
PubMed1996

Detection and widespread distribution of Chlamydia pneumoniae in the vascular system and its possible implications.

AIMS: To attempt to detect Chlamydia pneumoniae DNA in atheromatous vascular tissue. METHODS: A modification of an existing polymerase chain reaction (PCR) assay and immunofluorescence staining with a monoclonal antibody directed against C pneumoniae were used to detect C pneumoniae. Specimens from 32 patients undergoing abdominal aortic aneurysm repair were examined. Vascular tissue, ostensibly normal, from six liver transplant donors was also examined for comparison. Altogether, 43 vessels from these 38 subjects (age range 36-85 years) were examined. RESULTS: C pneumoniae was detected in 11 (44%) of 25 aortas, five (55%) of nine iliac arteries, two (40%) of five femoral arteries, and one of two iliac veins. Immunofluorescence staining supported positive PCR results in three of 12 cases in which it was used. Overall, C pneumoniae was detected in the arteries of 14 (44%) of the patients undergoing vascular surgery and three (50%) of the donors. CONCLUSIONS: This study is the first in the UK in which C pneumoniae organisms have been found in atherosclerotic vessels and the tendency for the organisms to be present most often in such vessels exhibiting chronic inflammatory changes suggests that a search for them in various forms of arteritis may also be rewarding.

Adult↗
PubMed1996

An introduction to dental electronic anesthesia.

Dental electronic anesthesia, although still in its infancy, promises to be an increasingly effective adjunct for the management of dental pain. Electronic anesthesia is noninvasive, safe, and generally well accepted by patients. Electronic anesthesia can be used for a wide variety of operative, prosthodontic, and periodontal procedures and the management of some orofacial pain conditions including temporomandibular dysfunction. While it is unrealistic to expect electronic anesthesia to replace traditional local anesthetic, this method provides a feasible alternative in the dentist's pain control armamentarium in certain situations.

Anesthesia, Dental↗
PubMed1995

Percutaneous needle cricothyroidotomy with repetitive airway obstruction.

To develop a technique for needle cricothyrotomy that mimics the normal respiratory cycle (using repetitive obstruction of the upper airway and relatively low flow oxygen through small catheters), a controlled trial in three anesthetized dogs was performed. Oxygen from a standard bottle and pressure reducer was delivered through the cricothyroid membrane at 0.36 L/kg/min, which is metabolically equivalent to 0.2 L/kg/min in an adult human. The upper airway was obstructed until the chest rose and then was unobstructed to allow exhalation. The animals were ventilated for 5 minutes to allow equilibration. Arterial PCO2 was measured after 2-minute periods of apnea and 3 minutes of ventilation, each repeated four times. The procedure was repeated in three other dogs at a flow of 0.18 L/kg/min to simulate a 50% air leak. Cricothyroid ventilation at 0.36 L/kg/min lowered the PCO2 from 65 mm Hg to 43 mm Hg, F = 258, P = .004. All PCO2 after 25 minutes were in the normal range. Ventilation at 0.18 L/kg/min stabilized the PCO2 at approximately 1.5 times normal (67 mm Hg versus 79 mm Hg for the preceding apnea, F = 77, P = .013). Flow rates achievable with 18- to 20-gauge catheters and standard oxygen sources are adequate for cricothyroid ventilation when the airway is repetitively obstructed to allow a normal respiratory cycle.

Airway Obstruction↗
PubMed1994

Written information needs of women who are recalled for further investigation of breast screening: results of a multicentre study.

OBJECTIVE: To assess the written information needs of women who are recalled for further investigation of breast screening. METHODS: Women from eight breast screening centres in England, Scotland, and Wales who had been recalled for further investigation were invited to complete a structured questionnaire about aspects of recall. Four hundred and eighty four consecutive women were invited to be interviewed immediately before assessment. Two weeks after attendance for assessment 2132 consecutive women (including all women who had been interviewed) were sent a postal questionnaire. No reminder was sent. Subjects from four of the centres received an information leaflet with their recall letter, the remainder did not. Letters/ leaflets used by the centres differed markedly. RESULTS: The response rate was 95% for the interview questionnaires and 70% for the postal questionnaires. Women who were prepared in advance for a possible recall were less likely to feel distressed/ very distressed when receiving a recall letter. The more aspects of the recall process included in the recall literature, the more women were likely to think that assessment had been explained (89% of women (544/ 609) receiving six or more items of information compared with 73% of women (269/370) receiving four or fewer items (P < 0.0001). Women who received a leaflet with their recall letter were significantly more likely to find some aspect of the information about recall reassuring than women who did not (61% (313/510) v 50% (278/557); P < 0.0001). Distressed/very distressed women were significantly more likely than somewhat/not distressed women to want further information about the reasons for recall (48% (403/834) v 26% (157/598); P < 0.0001 and how to get more information (29% (237/811) v 19% (116/ 616); P < 0.0001). CONCLUSIONS: Information can increase satisfaction and reduce distress. The amount of information women needed about recall was consistently underestimated. Inclusion of a leaflet improved satisfaction. Sensitive topics, words, and phrases should be carefully expressed.

Breast Neoplasms↗
PubMed1994

Periodontal considerations in restorative dentistry. 1: Operative considerations.

Restorative dentistry may be defined as the branch of dentistry that deals with the restoration or replacement of lost tooth structure, teeth or oral tissues. The practice of restorative dentistry has a reciprocal relationship with the maintenance of periodontal health. Untreated periodontal disease will compromise the success of restorative dentistry, and poor restorative treatment may have adverse effects on the periodontium by increasing accumulation of plaque and inducing changes in the composition of the plaque flora. Excessive occlusal stress and direct physical injury to the gingiva produced by the various dental procedures may also affect periodontal health. This is the first of two articles to look in depth at the periodontal considerations necessary in restorative dentistry, and covers the factors important in operative dentistry. The second article, which will be published in a later issue, will look at the situation with regard to prosthodontics.

Crowns↗
PubMed1992

Dental prosthetic status and needs of an elderly population living in long-term care facilities in Singapore.

This study examined the prosthetic status and needs among an elderly population living in long-term care facilities in Singapore. A total of 488 subjects were randomly selected and 479 of them were examined. The results show that 56.2 percent of selected subjects were edentulous while 43.8 percent had one or more teeth missing. The average number of teeth present among dentate subjects was 7.5. Of the edentulous subjects, 78 percent of them reported not having any dentures, and more than 20 percent of existing dentures were found to be defective and had to be replaced. A higher proportion (94 percent) of dentate subjects who could have benefitted from having partial dentures did not have them. The findings of this study clearly demonstrate high unmet needs for prosthetic care among an institutionalized elderly population.

Aged↗
PubMed1992

Dental state and needs for episodic care of institutionalized elderly in an Asian community.

This study examined the dental state of institutionalized elderly and their need for care. An oral examination was carried out on 479 elderly persons living in long-term care facilities with a mean age of 74.9 years. Results showed an overall DMF score of 27.0 and the average number of teeth in dentate subjects was 7.5. A large proportion of teeth (76.6%) was lost through dental caries and the loss increased significantly with age. Consequently, 56.1% of subjects were edentulous, of whom 78.8% were without dentures. Among the conditions that required urgent dental care, majority of subjects needed extractions of residual roots and loose teeth. A lesser proportion required treatment for gross caries (4.8%), periodontal disease (5.0%), suspected tumor (0.2%), as well as alleviation of pain and infection arising from mucosal lesions (4.8%), abscesses (3.3%) and TMJ problems (2.8%). The treatment needs for dentures and episodic care are high among institutionalized elderly and need to be addressed.

Aged↗
PubMed1991

The uaY positive control gene of Aspergillus nidulans: fine structure, isolation of constitutive mutants and reversion patterns.

The product of the uaY gene of Aspergillus nidulans is necessary for the expression of at least eight genes coding for enzymes and permeases of the purine utilisation pathway. A detailed fine structure map has been constructed of this gene involving 13 presumed point mutations and eight deletions. Gene conversion of these deletions was demonstrated. A technique was devised to select for constitutive mutations and two were obtained which map within the uaY gene. We have shown that the most centromere proximal allele reverts to a number of different phenotypes. The properties of this allele suggest that it may map in the open reading frame of the uaY gene, in a domain that could be altered in a way that would differentially affect the expression of genes under uaY control.

Aspergillus nidulans↗
PubMed1990

A survey of approximal root concavities in an ethnic Chinese population.

Eight hundred and forty teeth were surveyed, 60 approximal surfaces for each tooth type being studied. Approximal root concavities were completely absent in maxillary central incisors, in contrast with mandibular central incisors of which 73% had concavities on mesial surfaces and 93% on distal surfaces. Similarly, a markedly higher prevalence was found for mandibular lateral incisors and canines. However, mandibular first and second molars had fewer approximal concavities than their maxillary counterparts. In maxillary teeth, concavities were more frequent on distal surfaces, while for mandibular teeth no definite pattern was seen. In both maxillary and mandibular teeth, approximal concavities often started in enamel, extending down to the root surface. There were differences in the approximal root topography of Chinese teeth in comparison with other populations.

Bicuspid↗
PubMed1990

Oncoprotein stability after tumour resection.

The means by which oncogenes and their products activate malignant transformation are currently under intense investigation. However, published papers on experiments using human tumour material do not always report in detail their methods of collection or storage of the specimens. In order to assess the stability of oncogene encoded proteins following collection or storage of human tumour biopsies, we have examined the rate of decay of the c-myc, neu and EGF-receptor proteins. Solid tumours, containing amplified copies of each oncogene, were established in nude mice and the stability of the oncogene protein in portions of each tumour, left in phosphate buffered saline at room temperature for varying time intervals, was examined by immunoblotting. Intact EGF-receptor and neu oncoproteins were present even after 24 h under these conditions while the c-myc protein was apparently rapidly degraded after 20 min. These data demonstrate that oncogene products decay at different rates after tumour resection and that collection of human biopsies should take this into account in order to provide the basis for consistent measurements of protein expression.

Animals↗