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Biomedical subjects

L L Chong

Publications and source records attributed to L L Chong.

At least 19 recordsLinked to original sources
PubMed1988

Dental survey on soldiers of an infantry battalion of Singapore Armed Forces (SAF) at the time of completion of national service.

A three-part survey on 20-year-old national servicemen was conducted just before they left the army to determine their dental history and residual dental disease after two years of military service. The findings highlighted caries as a major cause of dental discomfort for which treatment was obtained. The impacted lower third molar was also a common cause of pain. The pattern of tooth loss showed that the lower first molar and the upper incisors were the teeth most frequently lost through caries. The findings reinforce the perception of the dental patient as being not the best person to appreciate his own dental needs and to do something positive about them.

Adult↗
PubMed1987

Comparison of stem cell viability of bone marrow cryopreserved by two different methods.

Two different cryogenic methods were used to study the preservation of murine bone marrow cells. Compared to the classical methods, in which separated mononuclear marrow cells in 10% dimethyl sulfoxide (DMSO) were cryopreserved in liquid nitrogen (-196 degrees C), a modified technique was carried out by cryopreservation of unfractionated marrow cells in a mixed protectant of 5% DMSO and 6% hydroxyethyl starch (HES) at -80 degrees C. Samples that were separately thawed after storage for 1, 4, 8, and 12 weeks were assayed for cell viability and recovery of CFU-GM and CFU-S. No macroscopic clumping of cells was noted either in fractionated or in unfractionated marrow cell cryopreservations. A mild damage, about 25% reduction of stem cells, was found at 1 week and did not deepen further. It seems that the greatest loss of stem cells occurred in the process of cryopreservation itself. Compared to prefreeze values, both a high number of cells that excluded trypan blue (87 +/- 3.4%) and a high recovery of CFU-GM (75 +/- 9.8%) and CFU-S (74 +/- 11.2) were observed in unfractionated marrow samples cryopreserved with the DMSO/HES mixture at -80 degrees C for 3 months and these results were very similar to those obtained from fractionated mononuclear marrow cells cryopreserved at -196 degrees C. The DMSO/HES protectant provides a simplified bone marrow cryopreservation technique that should be favorable to clinical application because of its high stem cell recovery and avoidance of cell-separation manipulation.

Animals↗
PubMed1986

Restriction fragment length polymorphism of the human beta-globin gene cluster: analysis of a beta-thalassemic family in Taiwan.

We have analysed seven polymorphic restriction sites of the human beta-globin gene cluster of six members of a Chinese family with a beta +-thalassemic sibling. The seven polymorphic sites analysed are the HincII site at the 5'-end of the epsilon-globin gene, the HindIII sites in the two gamma-globin genes, two HincII sites within and at the 3'-end of the psi beta 1 pseudogene, the AvaII site in the beta-globin gene and the BamHI site located at the 3' side of the beta-globin gene. The beta thal chromosome has been identified to have a haplotype of +----++ with respect to these seven polymorphic sites. This is also the most predominant haplotype associated with beta +-thalassemia in Mediterranean and Chinese populations (Chen et al., 1984; Orkin et al., 1982). Of the seven sites analysed in this family, four will be useful in prenatal diagnosis of beta-thalassemia in subsequent pregnancies in the family.

DNA Restriction Enzymes↗
PubMed1986

A case of 'superwarfarin' poisoning.

A young adult ingested 10 mg brodifacoum (a potent rodenticide) in an attempt to commit suicide. Prolonged bleeding was noted for over 6 months. It required large doses and prolonged use of vitamin K1 to combat this 'superwarfarin' poisoning.

4-Hydroxycoumarins↗
PubMed1986

Antiplatelet antibody determination using platelet factor 3 assay in thrombocytopenic patients.

Platelet factor 3 assay was used to detect antiplatelet antibodies in thrombocytopenic patients with platelet count less than 100,000/cu.mm. A total of 121 specimens was tested. The results gave a positive rate of 83% (61/74) for idiopathic (immune) thrombocytopenic purpura (ITP), 67% for systemic lupus erythematosus (SLE) and 54% (15/28) for others with & 13% (2/16) without history of blood components therapy. The sera from SLE without thrombocytopenic were also checked for the antibody, and a 14% positive rate was obtained. Patients with ITP with complete remission and normal platelet count were 40% positive. Antiplatelet antibody determination by platelet factor 3 assay is a sensitive and reproducible method. It can be performed in most laboratories and requires no specific equipment.

Autoantibodies↗
PubMed1986

Immunophenotyping of myeloma cells with immunoalkaline phosphatase technique.

An immunoalkaline phosphatase (IAP) technique was used to determine the class of cytoplasmic immunoglobulin presenting in the malignant plasma cells of patients with multiple myeloma. Using monoclonal antibodies against different human immunoglobulins (Igs) as the primary antibodies, and calf intestinal phosphatase as the enzymatic indicator. The presence of monoclonal immunoglobulin was demonstrated within the cytoplasm of malignant plasma cells. These results correlate well with the electrophoretic patterns of the Igs present in the serum samples of these patients. This IAP technique is suggested as a practical method for evaluating the immunophenotype of multiple myeloma.

Alkaline Phosphatase↗
PubMed1985

A case of factor V inhibitor.

A 57-year-old married Chinese male without a family history of bleeding disorder was presented with severe hemorrhagic tendency and was subsequently found to be suffering from an acquired inhibitor against coagulation factor V. The prolonged prothrombin time and activated partial thromboplastin time could not be corrected by the addition of normal plasma. Subnormal value of factor V level was noted accompanied with an abnormal platelet factor III availability test. With specific antisera and staphylococcal protein A, the inhibitor was characterized as an IgG(lambda) antibody. The hemorrhagic tendency and abnormal laboratory data were corrected after treating the patient with platelet concentrate transfusion and cyclophosphamide.

Blood Coagulation↗
PubMed1985

Development of chronic lymphocytic leukaemia in a case of Sjögren's syndrome with systemic lupus erythematosus.

Persistent lymphocytosis and intermittent fever were found in a 68-yr-old Chinese woman 5 yr after the diagnosis of Sjögren's syndrome with systemic lupus erythematosus (SLE). A series of examinations--including virology, bone marrow aspiration and surface markers of lymphocytes--was made to evaluate the nature of the lymphocytosis which had not been found previously. All of the results were consistent with the diagnosis of B-cell chronic lymphocytic leukaemia (CLL). Development of CLL in Sjögren's syndrome has seldom been described before and may be added to other malignancies associated with Sjögren's syndrome.

Aged↗
PubMed1985

Establishment and characterization of a new human lymphoma-derived cell line--HBL-2.

A new human B-cell lymphoma-derived cell line, designated HBL-2, was established from peripheral blood of a 17-year-old male during terminal leukemic phase. HBL-2 cells were single cell suspensions when cultured in RPMI 1640 with 10% fetal calf serum promoting a doubling time of about 20 hours. Cell marker studies revealed Ia and surface immunoglobulin positive, cytoplasmic immunoglobulin and Epstein-Barr nuclear antigen negative. Chromosome analysis showed a male aneuploid karyotype with 14q+ and other abnormal markers. Under electron microscopy, the cells exhibited clear nucleoli, fine chromatin, and were in a primary differentiated state. The establishment of HBL-2 cell line provides a powerful tool in studying the oncogenesis of B-cell malignancy.

Animals↗
PubMed1983

Monitoring heparin therapy--a role for the chromogenic assay.

Heparin therapy was evaluated by simultaneous determinations of the activated partial thromboplastin time (APTT), and plasma heparin levels by chromogenic assay. These tests showed good correlation (r = 0.73) in patients on heparin alone. However, in the presence of concurrent warfarin administration, r fell to 0.37, reflecting an additional warfarin effect upon the APTT. Furthermore, the studies confirmed the increased heparin requirement in patients with pulmonary embolization.

Biological Assay↗