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Biomedical subjects

L T Wang

Publications and source records attributed to L T Wang.

At least 19 recordsLinked to original sources
PubMed2001

Implications of muon g -- 2 for supersymmetry and for discovering superpartners directly.

We study the implications of interpreting the recent muon g(mu) -- 2 deviation from the standard model prediction as evidence for virtual superpartners, with very general calculations that include effects of phases and are consistent with all relevant constraints. Assuming that the central value is confirmed with smaller errors, there are upper limits on masses: at 1.5 sigma, at least one superpartner mass is below about 450 GeV (550 GeV) for tan beta = 35 (50) and may be produced at the Fermilab Tevatron in the upcoming run.

Journal Article↗
PubMed2001

Infrared patient positioning for stereotactic radiosurgery of extracranial tumors.

We report on a novel, non-invasive patient positioning system for radiosurgery of extracranial tumors. The system consisted of infrared cameras and reflective markers attached to the skin. Because localization accuracy is critical in radiosurgery, we performed a theoretical analysis of the accuracy of the system. A computer simulation program modeled errors in marker position, and was used to predict errors in targeting and study methods for minimizing errors. The use of redundant markers improved the overall accuracy of targeting. Experimental data was collected using a rigid torso phantom and correlated with theoretical results. The accuracy of the infrared system was compared with existing systems.

Computer Simulation↗
PubMed2001

[Comparative study on efficacy of qinggan granule and bushen granule in treating chronic hepatitis C].

OBJECTIVE: To evaluate the efficacy of Qinggan Granule (QGG) and Bushen Granule (BSG) in treating chronic hepatitis C (CHC) from blood donors clinically, biochemically and pathologically as well as to explore the therapeutical principle and methods of TCM. METHODS: Sixty-six patients with CHC were divided into three groups, the 36 patients in the QGG group treated with QGG, the 18 patients in the BSG group treated with BSG and the 12 patients in the control group untreated. The dose of QGG and BSG given was 30 g each time, three times per day for 6 consecutive months. Clinical and serum biochemical parameters as well as pathological change of liver biopsy before and after treatment were observed dynamically and compared. RESULTS: After treatment, in the two treated group, clinical symptoms were improved significantly, alanine transaminase (ALT) and aspartate aminotransferase (AST) reduced markedly. Moreover, QGG showed the effects of increasing albumin and lowering alkaline phosphatase (ALP). On the contrary, ALT still remained as before but AST further increased in the control group. Pathological examination showed that the inflammatory grade (IG) decreased in 42.2% and fibrotic stage (FS) decreased 21.2% of the patients in the QGG group, but no significant changes of the two indexes occurred in the BSG group, while in the control group, IG unchanged and FS increased in 3 cases. Chevallier's semi-quantity system analysis showed significant decrease of both scores in the QGG group (P < 0.05), only decrease of IG in the BSG group, and slight raise of IG and significant increase of FS (P < 0.05) in the control group. CONCLUSION: Condition of chronic hepatitis C patient would deteriorate progressively if not treated in time, especially the development of fibrosis. QGG and BSG could improve the clinical symptoms significantly, lower ALT and AST, eliminate inflammatory damage in the liver, slow down or reverse liver fibrosis process with stable long-term effect. Though most of the patients present a Syndrome of Liver-Kidney Yin-deficiency, the effect of QGG is superior to that of BSG, suggesting that the treatment of CHC should mainly be clearing principle, and method of clearing Liver and eliminating Dampness may be more suitable for them.

Adult↗
PubMed1999

SDS-induced conformational changes and inactivation of the bacterial chaperonin GroEL.

The inactivation and conformational changes of the bacterial chaperonin GroEL have been studied in SDS solutions with different concentrations. The results show that increasing the SDS concentration caused the intrinsic fluorescence emission intensity to increase and the emission peak to slightly blue-shift, indicating that increasing the SDS concentration can cause the hydrophobic surface to be slightly buried. The changes in the ANS-binding fluorescence with increasing SDS concentration also showed that the GroEL hydrophobic surface decreased. At low SDS concentrations, less than 0.3 mM, the GroEL ATPase activity increased with increasing SDS concentration. Increasing the SDS concentration beyond 0.3 mM caused the GroEL ATPase activity to quickly decrease. At high SDS concentrations, above 0.8 mM, the residual GroEL ATPase activity was less than 10% of the original activity, but the GroEL molecule maintained its native conformation (as indicated by the exposure of buried thiol groups, electrophoresis, and changes of CD spectra). The above results suggest that the conformational changes of the active site result in the inactivation of the ATPase even though the GroEL molecule does not markedly unfold at low SDS concentrations.

Adenosine Triphosphatases↗
PubMed1997

Unfolding and inactivation of Penaeus penicillatus acid phosphatase during denaturation by guanidine hydrochloride.

The conformational changes of penaeus penicillatus acid phosphatase during denaturation in guanidine hydrochloride solutions were studied by following changes in the intrinsic fluorescence, ultraviolet difference absorption, and circular dichroism spectra. Inactivation of the enzyme in guanidine hydrochloride solutions were compared with unfolding of the enzyme molecule. The results show that the extent of unfolding in guanidine solutions measured by several different methods closely coincide with each other and that slightly lower concentrations of guanidine are required to bring about inactivation than are required to produce significant conformational changes of the enzyme molecule. At the same concentrations, the inactivation rate constants are markedly faster than the rate constants for unfolding of the enzyme. The above results suggest that the active sites of this enzyme display more conformational flexibility than the enzyme molecule as a whole.

Acid Phosphatase↗
PubMed1996

Nested PCR-SSCP assay for the detection of p53 mutations in paraffin wax embedded bone tumours: improvement of sensitivity and fidelity.

DNA extraction and PCR amplification from paraffin wax embedded bone tumour specimens present several difficulties, firstly, because of the abundant matrix they contain and, secondly, because decalcification often causes degradation of DNA. In this report, comparative studies were carried out to determine the most efficient method for DNA extraction and PCR amplification from such specimens. The results indicated that nested PCR produced appropriate strong reaction products with minimal background contamination. A method for DNA extraction from paraffin wax embedded bone tissue and a nested PCR-SSCP technique have been developed for use in such diagnostic specimens.

Journal Article↗
PubMed1994

[A clinical study of inhibition of secondary cataract with heparin].

Extracapsular cataract extraction with posterior chamber lens implantation was performed on 47 eyes with senile cataract of which 25 eyes were in the control group and 22 eyes were irrigated with heparin solution (25U/ml) in the operation, the drug group. Postoperatively, 2 eyes with hyphema were found in the drug group, but the deposition of fibrin and cells on the anterior lenticular surface and the posterior capsular opacification were significantly less than those in the control group. 3 months after the operation, the mean visual acuity in the drug group was 0.70 +/- 0.26 markedly higher than that in the control group, 0.54 +/- 0.28 (P < 0.05).

Cataract↗
PubMed1994

[A cytological study of inhibition of secondary cataract with heparin].

Secondary cataract is caused primarily by migration and proliferation of fibroblasts on the posterior capsular surface after extracapsular cataract extraction. Human fetus skin fibroblast cell culture was used, by measurement of cell's life cycle, cellular DNA content, increase of cell number and density, to investigate the heparin inhibitory action on the growth of the cells. It is discovered that the growth rate of the fibroblasts is lowered in the culture medium with heparin and the inhibition takes place at the interval between G1 and S stage and at M stage of the cell's life cycle.

Cataract↗
PubMed1993

Bronchial carcinoid tumors in pediatric patients.

Bronchial carcinoid tumors (BCT) are the most frequent primary pulmonary neoplasms of childhood. Seventeen of 208 patients diagnosed as having BCT at the Massachusetts General Hospital were between 10 and 21 years of age. We reviewed our records of the 17 patients and 8 other pediatric cases and compared their findings with those of seven large series of adults. Distribution was equal between the sexes. The average age at diagnosis was 17 years; 4 patients were < or = 15 years old. The duration of symptoms prior to diagnosis varied from 2 weeks to 2.6 years, with a median duration of 8.5 months. In contrast to adults, no child was asymptomatic. The majority of children presented with wheezing and atelectasis in addition to the characteristic adult triad of cough, hemoptysis, and pneumonitis. Five patients presented with weight loss and one patient presented with hoarseness. One of the 17 pediatric patients presented with Cushing's syndrome and a functional BCT. Twelve of 14 patients were disease free for 9 months to 34 years after surgical resection. We conclude that BCT should be suspected in children with pneumonitis resistant to therapy, atelectasis, wheezing, and hemoptysis. Surgical resection will result in symptom-free recovery in the majority of cases in spite of low-grade malignancy.

Adolescent↗
PubMed1993

[Clinicopathological analysis, immunohistochemical study and electron microscopic observation of chondroblastoma of bone].

A series of 73 cases of chondroblastoma of bone, a rare benign tumor, was subjected to clinicopathological analysis, 50 cases of it were studied by immunohistochemistry and affinity histochemistry and 3 cases were observed by electron microscopy. In this series, chondroblastomas were found nearly in patients of all age groups, with the peak incidence occurring in the second decade of life. The lesions were more commonly located in long bone metaphyseal portion, especially in the upper end of femur and the head and neck of femur. It was easily misdiagnosed as giant cell tumor of bone, chondroma, and osteochondroma by clinic and radiography. There was gradual transition from a few chondroblasts to a small focus of clear cells in 3 cases, therefore, chondroblastoma may transform into clear cell chondrosarcoma by anaplastic change of chondroblast, which is one of malignant chondroblastomas. Our immunohistochemistry and affinity histochemistry results supported the point of view of chondroblast originated from epiphyseal chondrocytes. Immunohistochemical assessment of S-100 protein may be one useful parameter for differentiating chondroblastoma from giant cell tumor of bone and aneurysmal bone cyst ultrastructurally, chondroblasts had characteristic lobulated nuclei, compact zones under nuclear membrane, and microvilli on cells surface. In most cells, the Golgi apparatus and RER were inconspicuous without.

Adolescent↗
PubMed1993

Clear cell chondrosarcoma of bone. A report of three cases with immunohistochemical and affinity histochemical observations.

Clear cell chondrosarcoma, a subtype and separate entity from the traditional chondrosarcoma, is characterized by its special histologic features, site of predilection, slow growth and better prognosis. Three cases are presented with elucidation of clinicopathologic correlation and detection by the ABC immunohistochemical method using several antibodies. The observation of positive reaction to S-100 protein (S-100), vimentin (Vim), alpha 1-antichymotrypsin (AACT) and lysozyme (Lyso) by the tumor cells of clear cell chondrosarcoma, similar to traditional chondrosarcoma and chondroblastoma, proves that this tumor has its origin in the cartilaginous tissue. It was found for the first time that the clear cell chondrosarcoma was positive for wheat germ agglutinin (WGA) and concanavalin A (Con A). The authors believe that clear cell chondrosarcoma may result from the anaplastic changes of chondroblastoma cells into another subtype of that tumor. The osteoclast-like multinucleated giant cells (MGC), retaining the antigens of phagocytes, are not considered to be neoplastic.

Adult↗
PubMed1991

[Immunohistochemical study on clear cell chondrosarcoma].

Clear cell chondrosarcoma, a subtype and separate entity from the conventional chondrosarcoma, is characterized by its special histologic features, site of predilection, slow growth and better prognosis. Three cases are presented with elucidation of clinicopathologic correlation and detection by ABC immunohistochemical method using several antibodies. The observation of positive reaction to S-100 protein, vimentin, anti-alpha-chymotrypsin and Lysozyme by the tumor cells of clear cell chondrosarcoma, similar to chondrosarcoma and chondroblastoma, proves that this tumor has its origin from the cartilaginous tissue. It was found for the first time that the clear cell chondrosarcoma was positive for wheat germ agglutinin and concanavalin A. The authors believe that clear cell chondrosarcoma may result from the anaplastic change of chondroblastoma cells into another subtype of that tumor. The osteoblastlike multinucleated giant cells, retaining the antigens of phagocytes, are not considered to be neoplastic.

Adult↗
PubMed1991

[Hepatobiliary tuberculosis].

An analysis of 423 cases with hepatic and biliary tuberculosis was reported. The hepatic tuberculosis may be divided into miliary, nodular and abscess type, the biliary tuberculosis may be divided into cholecystic and biliary type.

Adult↗
PubMed1989

Giant cell tumors of bone. An immunohistochemical study.

Immunohistochemical study of giant cell tumor of bone (GCT) was carried out utilizing a panel of monoclonal antibodies including those against lysozyme, alpha-antichymotrypsin (AACT), vimentin (Vim), M718, HLA-DR, S-100 protein, epithelial membrane antigen (EMA), leukocyte common antigen (LCA), KB90, factor VIII related antigen (F VIII) against stromal cells and giant cells in 20 cases of GCT, with one case of prolonged continuously cultured cells GCT (GT 15). The results showed that stromal cells could be divided into two subgroups. Mesenchymal stromal cells labelled only with vimentin and were regarded as being derived from undifferentiated mesenchymal cells of bone marrow, while macrophage-like stromal cells labelled with antigens and were found to be present in mononuclear phagocytes. We believe this to be the first report that some stromal cells reacted positively with S-100 protein. Multinucleated giant cells were AACT and M718 positive, indicating their close relationship to macrophage-like stromal cells. The prolonged cultured cells accepted labelling with vimentin only indicating that all macrophage-like stromal cells disappeared after several subcultures and the only cells that could continue to be subcultured were the mesenchymal stromal cells.

Bone Neoplasms↗
PubMed1985

Direct intracellular measurement of non-linear postreceptor transfer functions in dark and light adaptation in Limulus.

Using one microelectrode inserted into a Limulus retinular cell, simultaneous recordings were made of the receptor potential evoked by light falling on that retinular cell and of the optic nerve action potentials generated in the eccentric cell coupled to that retinular cell. The postreceptor transfer function for sensory quantity was thereby examined directly between the retinular cell receptor potential and the eccentric cell action potentials over a more extended range than had been reported in previous studies. This transfer function exhibited a strong non-linearity; the function had 3 discrete linear segments. It is similar to the function relating extrinsic current to spike frequency in cat motoneuron. Light adaptation induced a shift of the transfer function. There were certain phenomenological similarities between the effect of light adaptation on the receptor and postreceptor transfer functions. But there were also enough dissimilarities to suggest that the mechanism of postreceptor adaptation is different than the receptor adaptation mechanism.

Action Potentials↗