Development of a quantitative real-time RT-PCR for kinetic analysis of immediate-early transcripts of rat cytomegalovirus.

One-step real-time RT-PCR assay was developed for quantification of the immediate-early (IE), namely IE1 and IE2 transcripts of Rat cytomegalovirus (RCMV), strain ALL-03 in rat embryonic fibroblast cells (REF). This in-house SYBR Green I based RT-PCR was shown to have higher amplification efficiency and detection limit as compared to a commercially available real-time RT-PCR kit in quantifying these two transcripts. The quantification histogram revealed the divergence of transcription activities of the two IE genes. The IE1 transcript had a concentration peak at 7 hrs post infection (p.i.), whereas IE2 transcript at 20 hrs p.i. Regulation of IE expression is critical for determination, whether the infection is going to be abortive, lytic or latent. Therefore, this in-house developed quantitative RT-PCR assay offers an alternative for diagnosis and monitoring of the acute cytomegalovirus (CMV) infection directed at IE transcript detection.

Pathogenesis and antibody response to a cytomegalovirus infection in newborn rats.

The present study described the kinetics of Rat cytomegalovirus (RCMV) infection in newborn rats by monitoring infectious virus and viral antigens in various organs, viral DNA in the blood (DNAemia) and antibody response. These parameters were evaluated quantitatively using double-antibody sandwich ELISA (DAS-ELISA), real-time PCR, indirect ELISA and virus infectivity assay. For the first time DAS-ELISA was used for detection of RCMV antigen directly from organ samples. The relationships between the presence of viral antigens in the infected organs and antibody levels were established by the Spearman's rank test. It was found that the virus was present in the blood, spleen, liver, lungs, and kidneys earlier than in the salivary glands. Furthermore, the early immunity of the newborn rats led to a delayed seroconversion. We suggested that the prolonged presence of the virus in salivary glands could augment the antibody response that conversely might be responsible for a reduction of viremia. This study expanded our understanding of RCMV pathogenesis leading to improved therapeutic and preventive treatment regimens particularly for the neonatal Human cytomegalovirus (HCMV) infections. Additionally, the detection procedures developed in this study such as DAS-ELISA and real-time PCR could serve as alternative techniques for rapid screening of large number of samples.

The metabolism of supplementary vitamin C during the common cold.

Ascorbic acid concentrations have been measured in leukocytes and plasma following oral administration of 2000 mg vitamin C in the same subjects while they had cold symptoms and after recovery from their colds. Plasma and leukocyte concentrations rose significantly in females, but only plasma concentrations rose in males, after the loading dose during colds. In the postcold tests, only plasma concentrations rose in both sexes. There was a significant difference in plasma leukocyte regression coefficients between the cold and postcold tests in females. Ascorbic acid passes into the plasma for metabolic purposes, and its storage is less in the leukocytes, during colds. Males had worse colds than females because their catarrhal symptoms were more severe. Higher tissue concentrations of ascorbic acid tended to be associated with low total, toxic, and catarrhal symptom values. A rise in tissue ascorbic acid was associated with less severe catarrhal symptoms in females. Ascorbic acid concentrations in the plasma and tongue were significantly higher after the subjects had recovered from their cold symptoms. Increasing the loading dose of vitamin C from 500 to 2000 mg more than doubled the leukocyte concentration of ascorbic acid in females. The higher dose enabled uptake of the vitamin into the leukocytes to take place over a 4-hour period. It did not give rise to increased uptake into male leukocytes. Administration of supplementary vitamin C elevated plasma ascorbic acid. The ascorbic acid then passed into the tissues depleted of vitamin C during the cold syndrome. A single supplementary dose of 2000 mg vitamin C can replete leukocyte ascorbic acid during a 4-hour period in females, but a larger dose may be necessary in males.

An improved method for the measurement of leucocyte ascorbic acid concentrations.

PIP: An improved method for measuring leucocyte ascorbic acid concentrations which employs sodium metrizoate instead of dextraven for separation of red blood cells out of the supernatant fluid is described. Results of duplicate analyses by the dextraven and metrizoic methods are described in school children, students, adults, and geriatric subjects, and it is shown that consistent results are obtained by both methods. Parallel analyses were performed onthe same samples of blood by the two methods. The metrizoic method gave values for leucocyte ascorbic acid concentrations 1.6 times as high as those obtained by the dextraven method. The time required for separation of the red cells was 3 times as long and contamination of the supernatant fluid with red blood cells was much greater in the dextraven method. The longer period required for separation of red cells in the dextraven method allowed a greater release of ascorbic acid from the leucocytes into the supernatant fluid than in the metrizoic method. This accounts for the higher leucocyte ascorbic acid concentrations found in the metrizoic method.^ieng

Prosthodontic management of maxillofacial defects after cancer surgery.

Surgery for maxillofacial cancer often creates a defect, which may affect speech, swallowing, mastication and facial appearance. The provision of a prosthesis is one method to help restore these physiologic and psychologic functions. Prosthodontic planning and rehabilitation should be an integral part of the team management to provide not just the preservation, but a quality of life for the patient. Various types of appliances are illustrated and the role of the dental surgeon is emphasised.

Clinical presentation of denture hyperplasia of oral tissues.

A clinical study on the presentation of denture hyperplasia was conducted on 15 patients with particular reference to age group, use and care of dentures, type and location of the hyperplastic lesion. The pilot study shows that a greater proportion of the studied sample were in the 50-60 years age group with a majority of them being unaware of the presence of the lesion in their mouth. Eleven of them responded that they use their dentures day and night. The incidence of lesions occurring in the lower jaw compared with the upper jaw was approximately 2:1. The average duration of denture usage was 8.7 years. Correct use of dentures and regular maintenance with professional care can help prevent the occurrence of these lesions.

The effectiveness of CO2 laser in dental surgery--a local experience.

The CO2 laser was introduced in Singapore in 1985 for dental surgery. It delivered a novel and brilliant adjunct for management of orofacial lesions and conditions. Tissue destruction is precise, immediate and quite bloodless. Oedema is not remarkable and healing produces minimal scarring. For small mucosal lesions, a power of 5 to 10 watts is sufficient. It is particularly useful for broad-based lesions and white lesions in the oral cavity. For major oral surgery, a power of 20 watts would be adequate for surgical excision. It reduces the invasiveness and trauma of surgery and lowers post-operative complications. The effects on dental hard tissues provide an exciting area for development and research and its uses here are gaining acceptance.

A case of Ludwig's angina following tooth extraction.

Ludwig's angina developed in an adult Chinese male following a mandibular third molar extraction. Brawny and tender swellings of the floor of the mouth and neck, with the elevation of the tongue, were classically present. The management of this case was based on the current emphasis of early broad-spectrum and antibiotic therapy with the maintenance of an adequate airway. The role of dental infection in this condition was highlighted.

Are the incremental lines in human cementum laid down annually?

A local Singaporean study of the presence of incremental lines in the cement of extracted teeth of 41 identity card-holding subjects is reported. The undecalcified roots of these teeth were sectioned transversely, some of which were stained with alizarin red. The lines observed were counted by one observer while blind to the actual ages of the subjects. A previous suggestion that these lines are deposited annually could not be supported in this sample, the number of lines tending to produce a lower estimated age than that registered on the identity card. The Pearson correlation coefficient for the line counts between two observers on 26 teeth was 0.73 (r2 = 0.535) which reflected difficulties in visualising the lines.

Intraoral vertical ramus osteotomy.

In corrective surgery for mandibular prognathism, the vertical ramus osteotomy, also known as the vertical subsigmoid osteotomy (VSS) is one of the simplest osteotomy to perform and therefore widely popular with oral & maxillofacial surgeons. Traditionally, the surgical approach for VSS is by the extra-oral approach although the approach may be either extraoral or intraoral. In this paper, the main advantages and disadvantages of the following three techniques, i.e. VSS via extraoral approach, VSS via intraoral approach and the sagittal split ramus osteotomy will be discussed. The vertical ramus osteotomy via the intraoral approach is not usually performed in Singapore until recently. The authors would like to present the observations and a surgical technique employed by them to perform VSS osteotomy via an intraoral approach.

Case reports: the use of intermaxillary screws to achieve intermaxillary fixation in the treatment of mandibular fractures.

INTRODUCTION: Treatment of mandibular fractures commonly involves the use of arch bars in temporary maxillo-mandibular fixation (also called intermaxillary fixation) to aid bone plating, for the postoperative application of light elastic traction to correct minor occlusal discrepancies and intermaxillary fixation for post reduction immobilisation. The purpose of this paper is to describe a quick and simple alternative for intermaxillary fixation. CLINICAL PICTURE: Three cases of mandibular fractures are presented to demonstrate the use of intermaxillary screws instead of conventional arch-bar wiring. TREATMENT: Two cases were treated with closed reduction methods while the other case was treated with open reduction. OUTCOME: Subsequent fracture healing was not compromised using this technique. CONCLUSIONS: With careful case selection, successful treatment outcome may be achieved using this time-saving and technically simple procedure. Some of the advantages and disadvantages of the intermaxillary screws are discussed.

Root morphology of the maxillary first premolar in Singaporeans.

Extracted teeth were collected from clinical procedures performed in the Faculty of Dentistry, National University of Singapore. A selected sample of 957 maxillary first premolars were subjected to visual examination and digital radiography. There was a higher incidence of two-root form (50.6 per cent) than previously reported for the Singaporean dentition. In the two-root category, 307 teeth exhibited the fused-root form (two fused roots with two root canals) and 177 were distinctively of the two-root form (two separate roots with two root canals and two foramina). The fused-root form was emphasized as an entity in this study. The one-root form accounted for 49.4 per cent. No three-root form was detected.

Mongoloid features of the permanent mandibular second molar in Singaporean Chinese.

The permanent mandibular second molar is usually described as four-cusped, two placed buccally and two lingually. It has been reported that five-cusp forms were more commonly present in dentitions of mongoloid origin. The prevalence and features of this tooth form were examined in a Singaporean sample of 380 subjects with bilateral presence of the mandibular second molars. One-hundred and sixty four cases (43.1 per cent) were found to have bilateral occurrence of five-cusp forms and thirty-four cases (8.9 per cent) with unilateral occurrence. Six-cusp forms were detected in three cases. There was almost equal prevalence in both sexes and both sides were equally involved in unilateral cases. The extra cusp was smallest, placed disto-buccally and sometimes midway at the distal border. The occlusal outline of five-cusp second molars was rectangular with a somewhat similar groove pattern to the first molar. There was an increase in the mesio-distal width of the crown. The high incidence was comparable with other studies of mongoloid dentitions and it could be considered as an important morphological and racial characteristic of the Singaporean Chinese.

Coronal morphology of the mandibular second premolar in the Singaporean Chinese.

Five hundred and sixty-four patients of Singaporean Chinese origin with bilateral second premolars present were screened. Morphological features of the crown, number and position of cusps and the sex of the patient were recorded. The mesio-distal dimensions of the crowns were measured. Three hundred and seventy-four (66.3 per cent) exhibited bilateral 2-cusp forms; 143 (25.4 per cent) were 3-cusp forms; and 47 (8.3 per cent) were mixed. There was no sex predilection in the three groups. In the 2-cusp forms, the predominant occlusal pattern was H-shaped (75.9 per cent). The 3-cusp type with a Y-shaped pattern and a squarish outline is a significant morphological and racial characteristic in the local population. The presence of 2-cusp and 3-cusp forms in an individual is an unusual developmental phenomenon.

Incidence and features of three-rooted permanent mandibular molars.

Seven hundred and eighty-six patients of Singaporean Chinese origin requiring extractions of permanent mandibular molars were screened. Personal details, identification of the tooth and the presence or absence of an extra root were recorded. Thirty-two cases (4.1 per cent) exhibited an extra disto-lingual root. None was found in the second molar. The first molar was affected (7.9 per cent) slightly more than twice as often as the third molar (3.7 per cent). The extra root was present almost equally in both sexes with a higher presentation on the left side. Six cases had a fracture of the extra root. A comparison was made with a study done by Tratman' on the same population and with other studies involving those of Chinese and Mongoloid origin in other countries.

Laser therapy for a haemophiliac. Case report.

With adequate precaution, dental procedures which are likely to cause haemorrhage in haemophiliac patients may now be performed with a greatly reduced risk. A case report of a 'moderate' haemophiliac who presented with acute pericoronitis is described. The operculum associated with an erupting molar tooth was excised using a laser beam. Pre- or post-operative infusion of Factor VIII was not required. The applications and possible implications of the use of this treatment modality are discussed.

A ten-year follow-up case report following surgical correction of anterior open bite.

A case is reported whereby an anterior open-bite was treated with the Köle osteotomy in an adult Chinese girl. This study documents cephalometrically the post-treatment changes occurring in the dento-alveolar complex over a ten year follow-up period and describes the possible mechanisms contributing to the remarkable stability of the open-bite correction.

Histiocytosis X (Langerhans-cell histiocytosis) of the palate. Case report.

A case of histiocytosis X (Langerhans-cell histiocytosis) occurring in the maxilla of a two-year-old boy is presented. Common dental and oral conditions were considered and eliminated. Diagnosis was made through a biopsy which showed aggregates of histiocytes. Management consisted of multi-modal treatment. Full skeletal radiographic survey and review were essential to detect other possible sites of involvement. None was found in this case over a four-year review.

'A bridge too far ...'. Case report.

An elderly man was assaulted and sustained facial injuries with fractures of the mandible and left zygoma. An unusual complication of aspiration of an intact four-unit metal bridge is reported. Immediate retrieval was done under general anaesthesia by rigid bronchoscopy. The technique is described. The importance of careful clinical and radiographic examination is stressed.