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Biomedical subjects

T Leung

Publications and source records attributed to T Leung.

98 records · Page 6Linked to original sources
PubMedDate not supplied

Intracranial germ cell tumors in children with and without Down syndrome.

PURPOSE: Two Chinese children with Down syndrome affected by intracranial germ cell tumors are described. Because they represent two of eight affected patients in the current series from 1990 to 1996, it is postulated that such occurrence may be more than a coincidental event. PATIENTS AND METHODS: Two children with Down syndrome developed germ cell tumors in atypical intracranial sites that affected basal ganglion and cerebellum. The pathology showed germinoma and yolk sac tumor, respectively. These were treated by radical surgical resection and chemotherapy with cisplatin, etoposide, and bleomycin, but without radiotherapy. RESULTS: One patient survived 3 years without radiologic evidence of tumor. The other died from infective complications caused by severe myelosuppression after chemotherapy. CONCLUSIONS: Subtle neurologic manifestations in developmentally handicapped patients with intracranial space-occupying lesions could result in delayed diagnosis. Children with Down syndrome suffering from brain tumors may have a higher chance for germ cell tumors. Assay for alpha-fetoprotein and beta-human chorionic gonadotrophin could hasten diagnosis in some cases. This observation and review of literature suggest an increased risk of developing intracranial germ cell tumors in subjects with Down syndrome.

Antineoplastic Combined Chemotherapy Protocols↗
PubMedDate not supplied

Retention profiles of stud-type precision attachments.

This study measured the retention profiles of 11 commercially available stud-type attachment systems suitable for use with overdentures. The vertical distance over which resistance to separation existed was recorded and related to the configuration of the attachments. In many of the systems tested, only a small portion of the vertical length of the attachment contributed to the retention of the unit.

Denture Design↗
PubMedDate not supplied

Inaccurate fit of implant superstructures. Part 1: Stresses generated on the superstructure relative to the size of fit discrepancy.

This laboratory study used a photoelastic-coating technique to investigate the relationship between the magnitude and location of discrepancies of fit and the amount and distribution of surface stresses on an implant superstructure. For the test superstructure involving four abutments and a single fit discrepancy, maximum surface stress was found over the intermediate abutment, regardless of the location of the fit error. The results show a positive relationship between the size of the fit discrepancy and the magnitude of stress on the superstructure for gaps of up to 104 micrometers at an end abutment and 55 micrometers at an intermediate abutment, when the gold screws were tightened at 10-Ncm torque.

Dental Abutments↗
PubMedDate not supplied

Inaccurate fit of implant superstructures. Part II: Efficacy of the Preci-disc system for the correction of errors.

The Preci-disc prosthetic system for dental implants is designed to compensate for casting inaccuracies and to reduce stresses generated on the superstructure and implant components. This laboratory study compared stresses induced on the implant superstructure with various sizes of vertical discrepancy of fit, with and without the application of the Preci-disc system. A series of test casts carrying four abutment replicas were fabricated incorporating various sizes of discrepancies (10 to 100 micrometers) relative to a master superstructure. The stress generated on the superstructure was quantified using photoelastic stress analysis. It was found that the Preci-disc system was effective in reducing stresses induced on the surface of the implant superstructure particularly with greater discrepancies of fit (60 to 100 micrometers).

Composite Resins↗