Biomedical subjects
Publications and source records attributed to C Tan.
Procedure of a electrode for atrial epicardial mapping (template electrode) is introduced in this paper. It is easy to made, we can get sharp and clear waveforms and a constant baseline while mapping. If the electrode is connected with computer, it is able to be used for epicardial mapping of atrial arrhythmias, especially atrial fibrillation in real time.
The study was carried out to observe the effect of nickel chloride (NiCl2) on T-lymphocyte subsets, CD4, CD8 and CD4/CD8 ratios in vivo. BALB/C mice were injected i.p. with NiCl2 every other day for 2 w. The NiCl2 doses were 1, 3, 6, 9 or 12 mg/kg. Lymphocytes were obtained from mouse spleen and cultured in the presence of monoclonal antibody FITC conjugated, anti-CD4 or anti-CD8. Samples were determined with a flow cytometer. A suppressive effect on CD4-positive cells was found in the 6 mg/kg group, but this subset was restored to the control level in the 9 and 12 mg/kg groups, suggesting that there was an "immune tolerance" effect. No significant changes were found in CD8-positive cells and CD4/CD8 ratios. The results suggested the NiCl2 had a deleterious effect on mouse T-lymphocytes in short-term in vivo exposure, but the effects may depend on the dose and cell subset.
The population of Singapore is ageing rapidly. Acute hospitals in Singapore are also experiencing an acute bed shortage. However, many elderly admitted to acute hospitals require a longer period of convalescence before they are able to go home. Community hospitals are most suitable to provide such care for the elderly patient. Patients could be discharged to the community hospitals to continue rehabilitation and convalescence. In addition this would also free the beds in the acute hospitals. However, there is a risk that without adequate discharge planning, the community hospitals would in turn also reach full capacity and no longer be able to accept patients. A discharge planning programme has been set up in a community hospital to address the following needs: 1) caring for a rapidly ageing population with increasing degrees of disability; 2) the shortage of beds in the acute hospitals; (3) the provision of holistic care and care-giver education, and 4) to prevent long term institutionalisation of the elderly as much as possible.
It is essential for the study of T-cell function and the improvement of adoptive cell therapies to efficiently generate large populations of human primary T cells that reliably express foreign genes. This goal is achieved by using recombinant retroviruses pseudotyped with either the gibbon ape leukemia virus (GaLV) envelope or the vesicular stomatitis virus G (VSV-G) glycoprotein. We show here that both retroviral particles mediate stable gene transfer in CD4+ and in CD8+ peripheral blood lymphocytes cultured under optimized conditions. However, VSV-G-pseudotyped virions may cause transduction artifacts that must be carefully excluded. The VSV-G virions require 10- to 100-fold higher concentrations of infectious particles to achieve levels of gene transfer comparable to GaLV-virions. Nonetheless, the physical stability of VSV-G-coated particles enables the concentration of viral stocks to 10(9) infectious particles per milliliter or more.
Galanin (GAL) is a widely distributed neuropeptide with diverse biological effects including modulation of hormone release, antinociception and modification of feeding behavior. Its effects are mediated through G-protein-coupled receptors (GPCR) for which only a single type has been cloned, GAL receptor 1 (GALR1). We describe the cloning of a second galanin receptor type, GALR2, from rat hypothalamus. The GALR2 amino acid sequence is 38% identical to GALR1 and is pharmacologically similar to GALR1 when expressed in COS-7 cells. GALR2 is encoded by a single gene containing at least one intron and expressed in a diverse range of tissues.
It is essential for the improvement of adoptive cell therapies to generate efficiently large populations of human primary T cells that reliably express a suicide gene conferring drug sensitivity, such as herpes simplex virus thymidine kinase (HSVtk). We show here that an optimized dicistronic vector containing the encephalomyocarditis virus (EMCV) internal ribosomal entry site (IRES) is functional in human primary. T lymphocytes that bear on average one integrated vector copy per cell. We demonstrate reliable coexpression of the marker NTP, an inactive mutant of the human low-affinity nerve growth factor receptor and HSVtk. In the dicistronic vector NIT, NTP is expressed as a cap-dependent marker and HSVtk as a nonselectable IRES-dependent gene. Cell-surface expression of NTP is sufficient to allow for the efficient and rapid enrichment of the transduced cells to high purity. Of these purified lymphocytes, 97 +/- 4% and 92 +/- 6% are selectively eliminated when cultured in the presence of 1.0 or 0.1 microM ganciclovic respectively, establishing that the EMCV IRES ensures efficient and sufficient expression of two genes in human primary T cells.
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We analyzed Ct findings of 10 cases with parathyroid adenoma which had been verified by surgery and pathologic section. The correct localization of 9 adenomas was made by CT preoperatively. The method of CT scanning of parathyroid adenoma were elucidated. The results showed that most adenomas were located in the groove between trachea and esophagus. The contour of tumors was oval, the edge was smooth and regular. Enhancement CT images were helpful for differentiating the tumor from blood vessel. It is indicated that CT scanning is a good method for localizing the parathyroid adenoma.
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Twenty one cases of kaposi's sarcoma (KS) with manifestation in the field of otolaryngology are reported. The incidence of KS is increasing following epidemic of AIDS all over the world. Epistaxis, nasal obstruction, sore-throat, dry of foreign body filling in throat and nodal mass are most frequent manifestation. The relationship of KS with HIV, it's pathology and diagnosis are discussed.
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The Drosophila retrotransposon, 412, is expressed in a cell-specific manner during embryogenesis. At stage 11, 412 transcripts are present in bilateral clusters of cells within the mesoderm. The posterior clusters of 412-positive cells become associated with the gonads at stage 13; however, the fate of the cells in the remaining clusters is unknown. We have tested by in situ hybridization to whole-mount embryos the possible identity of these cells with known precursor cell types present in bilateral clusters. We simultaneously located the 412-positive cells and the precursor cells to visceral muscle or the fat body. We have determined that the 412-positive cells do not correspond to these precursor cells and that the development of the visceral muscle or fat body does not affect the expression of 412 during embryogenesis.
PI-specific PLC enzymes are a key component of phosphatidylinositol-mediated signaling pathways since the hydrophobic product, diacylglycerol, activates protein kinase C and the water-soluble product, inositol trisphosphate, is involved in Ca2+ mobilization. Nonspecific, or PC-PLC, enzymes can generate diacylglycerol without Ca2+ mobilization. A series of inhibitors, both lipophilic and water-soluble, have been synthesized to target each of these two classes of PLC enzymes. Design of the inhibitors was based on proposed enzyme mechanisms and available crystal structures. The solution conformations of the lipophilic phospholipid analogs, (diheptanoylphosphatidyl(2-O-methyl)inositol for PI-PLC and a dihexanoyl-sn-(3-N-benzylaminoglycero)phosphoramidocholine for PC-PLC, have been determined using NMR methodology and the interaction of these compounds with bacterial enzymes has been examined. Water-soluble inhibitors include strained cyclic phosphonates for PI-PLC and vanadate for PC-PLC. An eventual goal of this work is to generate compounds that specifically target each type of intracellular PLC activity.
PURPOSE: To evaluate in children the impact of contemporary treatment for Hodgkin disease on the pattern of growth and final height. PATIENTS AND METHODS: We studied 80 patients (54 males) aged <14 years at diagnosis, with newly diagnosed, pathologically confirmed Hodgkin disease, treated at a single institution. Forty six patients received chemotherapy (CT) + radiotherapy (RT), 23 patients received RT alone, and 11 patients received CT alone. Heights were obtained at diagnosis, at the end of treatment, 1, 2, and 3 years after the end of treatment and at attainment of final height. Heights were converted to age- and sex-adjusted SD scores (SDS). RESULTS: There was a significant change in height SDS at the end of treatment compared to height SDS at diagnosis for all three groups (CT + RT: -0.33, p<0.001; RT: +0.09, p=0.027; CT: -0.24, p=0.012). Over the 3 years following treatment, the rate of change of height SDS was not statistically different between the three treatment groups. Final height SDS was decreased for patients receiving RT + CT (-0.41 SDS, p=0.02; n=31). The change in final height SDS for patients receiving RT or CT only was -0.36 (n=14) and +0.42 (n=4), respectively. Loss of final height SDS correlated with younger age at diagnosis (p=0.005). Patients receiving higher RT doses tended to fare worse (p=0.08). CONCLUSIONS: Pediatric patients treated for Hodgkin disease with the combination of RT and CT suffer a small but significant decrease in their final height SDS. Younger patients and those treated with higher RT doses appear to experience the greatest loss of height potential.
Previously published papers on the success of trabeculectomy as a treatment for glaucoma show success rates between 67% and 84%. The success rate of trabeculectomy in Afro-Carribean patients was observed to be lower than in Caucasian patients. It has been commonly believed that the success rate of trabeculectomy in Oriental/Asian eyes would lie somewhere between these. We reviewed the records of 51 consecutive trabeculectomies performed in the National University Hospital, Singapore and found that our success rate was lower-43.1% overall and 48.7% for primary glaucomas.
Although dihydrofolate reductase (DHFR) gene amplification is a common mechanism of resistance to methotrexate (MTX) in tumor cell lines, with the exception of a few case reports, the incidence of this phenomenon as a mechanism of MTX resistance in the clinic has not been reported. We studied 38 untreated patients and 29 patients in relapse with acute lymphoblastic leukemia (ALL) for gene amplification and p53 gene mutations. Three patients were studied both at diagnosis and at each of two relapses after treatment with MTX. Nine of 29 relapsed patients (31%) had low-level DHFR gene amplification (two to four gene copies) associated with increased levels of DHFR mRNA and enzyme activity. Of significance was a correlation of gene amplification with p53 mutations in seven of nine relapsed patients (P < .001). Low-level DHFR gene amplification may be an important cause of MTX resistance in ALL and strengthens the concept that mutations in the p53 gene may lead to gene amplification as a consequence of defective cell cycle control.
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Lead nephropathy in adults is silent and insidious, characterized by the absence of proteinuria in its early phase. Of the early markers of nephrotoxicity, urinary N-acetyl-beta-D-glucosaminidase (NAG) appears to be the only one that is elevated in early lead nephropathy. However, the elevation in urinary NAG activity may be a response to a sharp increase in renal burden of lead. Its usefulness as a marker of chronic lead nephropathy is thus in doubt. There is a need, then, to identify a reliable early biological indicator of lead-induced kidney damage. Furthermore, there is also a need to identify suitable markers of chronic exposure to describe meaningful dose-response and dose-effect relationships. Traditionally, blood lead (PbB) was used, but the current blood lead level (PbBrec) is more an indicator of recent exposure. Time-integrated blood lead indices (PbBint) derived from repeated serial PbB measurements can be used as indices of chronic exposure. In 128 lead-exposed workers, the PbBint was the most important exposure variable in describing the variability in urinary alpha 1-microglobulin (U alpha 1 m), urinary beta 2-microglobulin (U beta 2m), and urinary retinol binding protein (URBP). U alpha 1m was the only marker that was significantly higher in the exposed group, with a good dose-response and dose-effect relationship with PbBint. The lack of dose-response and dose-effect relationships in other studies may be due to inappropriate exposure markers as well as less sensitive response markers. PbBint has a better correlation than PbBrec. Furthermore, U alpha 1m may be the most sensitive of the markers because of its higher molecular weight.