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Biomedical subjects

C H Feng

Publications and source records attributed to C H Feng.

At least 19 recordsLinked to original sources
PubMed1998

Multiple-phase model of memory consolidation confirmed by behavioral and pharmacological analyses of operant conditioning in Drosophila.

Previous work on classical olfactory learning and memory in flies has suggested at least four distinct phases of memory consolidation. Similarly, our behavioral and pharmacological analyses also provided clear evidence for at least four pharmacologically distinct memory phases in flies after operant conditioning. Anesthesia-resistant memory (ARM) is present between about 20 and 120 min after training, and susceptible to disruption by the ATPase deactivating chemicals such as ouabain and ethacrynic acid (EA). Long-term memory (LTM) is activated at least 150 min after training, and can be disrupted by protein synthesis inhibitors such as cycloheximide (CXM). In addition, a very short-term memory (pre-STM) is demonstrated by feeding flies with potassium chloride (KCl), which has been shown to disrupt the short-term memory. These observations confirm our previous argument that memory formation in flies involves an intricate, multiple-phase pathway of consolidation.

Animals↗
PubMed1997

Nutritional effects on operant visual learning in Drosophila melanogaster.

The nutritional effects on operant visual learning behavior were investigated in a flight simulator. Operant visual learning and memory formation were normal in Drosophila (S-flies) reared on standard medium, but absent in flies (P-flies) raised on Peking medium. S- and P-flies were transferred to the alternative medium soon after hatching and their progeny was also raised on corresponding medium for several generations. respectively. S-flies transferred showed significantly reduced learning acquisition and 20 min memory retention, and operant visual learning along with memory formation was abolished in their progeny within three generations. Transferred P-flies recovered slowly their learning acquisition and memory formation to normal levels within five generations. Further studies suggested that low protein and minerals or high carbohydrate contents in Peking medium might be related to abnormal performance of P-flies. These results confirm the feasibility of affecting learning behavior by dietary regimens and developing an insect model of maternal malnutrition for pre- or post-natal malnutrition in Drosophila.

Animal Feed↗
PubMed1994

[Flow cytometric analysis of DNA in giant cell tumor of bone].

The DNA content of 44 giant cell tumors (GCTs) was determined by flow cytometry and simultaneous analysis of cell surface antigens and cellular DNA was performed in two of these GCTs. Two grade III GCTs, one with lung metastases, were all aneuploid. Out of 42 grades I and II GCTs, 16 were aneuploid, statistically, there was no difference in proliferative activity and rate of aneuploidy between grade I and grade II GCTs, but significant difference between primary and local recurrent GCTs existed. After 5 passages in culture the proliferative rate of cells in 13 GCTs increased significantly, the rate of cells bearing GCT associated antigen stepped up and in 2 GCTs tested specially. All these findings demonstrate: (1) the morphological difference of these tumors was not remarkable (2) DNA determinations as an adjunct to conventional histopathologic assessment may provide objective clinically relevant information for prognosis, (3) tumor and non-tumor cells co-exist in GCTs and only tumor cells could survive in long-term culture in vitro.

Aneuploidy↗
PubMed1994

[p53 antioncogene abnormal in osteosarcoma].

Immunohistochemical evaluation of 24 osteosarcoma using an anti-p53 protein monoclonal antibody (Moab p53-12) showed strong positive reaction in the nuclei of tumor cells in 14 osteosarcoma (58.3%). Many studies have proved that this overexpression of p53 protein in tumor cells is associated with mutation of the p53 gene. Contrast study with DNA flow cytometry made on osteosarcoma showed that most of the p53 strongly positive tumors have higher DNA Index value than negative or slightly positive ones, though no statistically difference existed between two groups. Southern blot hybridization of p53 gene was also made in osteosarcomas. 5 of 20 cases (20%) had the structural changes of p53 gene. 3 of them were part or whole deletion of the gene. 2 of them had the extra-band, indicating the rearrangement of the gene.

Adolescent↗
PubMed1992

A study of Chinese knee joint geometry for prosthesis design.

This study for the first time provides the geometric parameters of the knee joint of Chinese, which is indispensible to the design of knee prosthesis used for compatriotic patients. Thirty-five items, including linear, radial and angular measurements, were taken from 105 cadaveric knees and knee X-ray films of 1,100 subjects. The method and calculation for proper correction of the X-ray image magnification and joint cartilage space was established. Correlation was found to exist between the X-ray correction coefficients and the body weight, which formed the basis for individualized correction of X-ray measurements. Statistical analysis revealed that most of the linear and radial measurements were highly related while the angular measurements were independent of others. Principal component analysis showed that the width of femoral condyle might be taken as the leading index in determining the dimension of the knee, and regression functions were established to supply the serial parameters for prosthetic design. Multivariate discriminate functions could aid the selection of knee prosthesis.

Anthropometry↗
PubMed1991

Quantitative pathological study of aggressiveness of giant cell tumor of bone.

Clinical behavior of giant cell tumor of bone (GCT) may vary remarkably from latent to very aggressive. Quantitative pathological methods were used to evaluate the aggressiveness of GCT. Fifteen cytometric parameters were measured and computed on routine sections of 40 GCTs which had been treated with curettage. The surgery factor (with or without additional procedures like bone cement packing or freezing after the curettage) was also taken into account and computed. Nineteen of the 40 GCTs were cured and 21 recurred. While no single one from the 15 parameters measured showed significant differences between the cured and recurrent groups according to the Mann-Whitney's U test or Student's t test, a 4-variable function was established with a stepwise discriminant analysis which could correctly identify 70.8% of the predicted cases as cured or recurrent (jackknife procedure). The function also suggested that in addition to the surgery factor, which no doubt had close relation with the prognosis, the most important risk factor in histological parameters was SA40, i.e. the percent of cells with nucleus larger than 40 square microns. Single cells extracted from paraffin-embedded blocks of 38 GCTs were analyzed by DNA-image cytometry. The 2c deviation index (2cDI) showed wide heterogeneity ranging from those consistent with benign tumors to those with apparent malignant ones, which may account for its diversity in clinical behaviour. Sixteen of the 38 cases had been treated with curettage, 8 of them were cured and followed up for at least 3 years and the remaining 8 recurred. The significant difference of 2cDI between the two groups suggested that these DNA parameters are useful in evaluating the aggressiveness of GCT for the selection of an adequate treatment. Quantitative approaches appeared to be more objective and more sensitive in evaluating the aggressiveness and predicting the prognosis of GCT than the subjective grading system used before.

Bone Neoplasms↗
PubMed1990

[Cellular biological study of giant cell tumor of bone: a 10-year summary].

This article is a summary of the main research accomplishments on giant cell tumor of bone (GCT) carried out in this laboratory in the past ten years. The stromal cells (STC) in GCT have long been regarded as a single neoplastic element. By means of immunological method they are segregated into EA rosette-forming cells (RFC) and non-rosette-forming cells (NRFC). It is herein demonstrated that RFC are macrophages of the defensive mechanism, while NRFC bear the hallmarks of neoplastic cells. The views concerning the nature of the multinucleated giant cells (MGC) so far remains controversial. One of the authors, on the basis of the survival time in thin vitro culture, classifies them into short survival MGC (S-MGC) and long survival MGC (L-MGC). Immunological and cytochemical evidences indicate that S-MGC are similar to osteoblasts and foreign-body giant cells and express macrophage antigen. Moreover, macrophages in GCT can actually form MGC. L-MGC, however, present characteristics of neoplastic cells which are known to be able to form tumor giant cells. Thus the concept of GCT has been renovated. Evaluation of the aggressiveness of GCT is important and challenging, as the Jaffe grading system is no longer widely considered valid. In our laboratory this problem has been approached by cytomorphometry, nuclear DNA-cytometry and multifactor analysis techniques. Parameters which are conducive to predicting the prognosis of GCT are found, which would render help to clinical diagnosis and research of this semimalignant tumor.

Bone Neoplasms↗
PubMed1989

Contrast study on multinucleated giant cells in giant cell tumors of bone and other multinucleated cells.

By means of tissue culture, electron microscopy, cytochemistry, indirect immunofluorescence and immunohistochemistry, the multinucleated giant cells(MGCs) in 12 giant cell tumors of bone (GCT) were studied in contrast with osteoclasts (OCs), foreign body giant cells (FGCs) and inflammatory giant cells (IGCs). The findings in the majority of MGCs were identical with those in OCs, suggesting that they most probably derived from the same precursor. Continuous in vitro culture revealed two kinds of MGCs, which were designated preliminarily as short-lived MGCs and long-lived MGCs for their difference in morphology and in several biological features, which suggests two kinds of MGCs exist in GCT. We conclude that the short-lived conform to the typical MGCs known generally to the pathologists, while the long-lived are deemed to be closely related to the neoplastic elements of the tumor.

Animals↗
PubMed1989

Computer simulations of figure-ground discrimination in the visual system of the fly.

Figure-ground discrimination and pattern discrimination represent one of the most important problems in computer vision. Based on computational neuronal network model proposed by Reichardt et al. for figure-ground discrimination in the visual system of the fly, entire systematic computer simulations were carried out under nonstationary conditions. Results show that the model network and simulations have predictive power for behavioural experimental results. This paper proposes that motion perception and elementary pattern discrimination in human visual system may be mediated by some kind of figure-ground system with movement detectors as input layer.

Animals↗