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Biomedical subjects

C Feng

Publications and source records attributed to C Feng.

At least 73 records · Page 4Linked to original sources
PubMed1996

[Diagnostic value of color Doppler flow imaging in gestational trophoblastic diseases].

OBJECTIVE: To investigate the value of color doppler flow imaging (CDFI) and pulsed doppler (PD) determinations in early diagnosis, evaluation of therapeutic effects and prediction of prognosis of gestational trophoblastic diseases (GTD). METHOD: CDFI and PD were performed in 55 cases of GTD and 30 normal pregnant women as controls. RESULTS: The uterine muscular layer in GTD showed multicolored abundant blood flow and blood sinuses. Blood flow resistance was low with a resistance index (RI) less than 0.5. After chemotherapy the RI changed dramatically. Pathological evidences were found in surgical specimens of 8 patients. Findings of pelvic hysterography in 16 cases were in accordance with the results of CDFI and PD determinations. CONCLUSION: CDFI and PD as new methods for early diagnosis of GTD can also be used to evaluate the chemotherapeutic results as well as to determine the prognosis of the disease.

Adult↗
PubMed1996

P53 gene abnormalities in osteosarcoma.

OBJECTIVE: The P53 tumor suppressor gene shows the most frequent genetic alteration in human tumors. Mutation, deletion and rearrangement of P53 gene have been found in several types of neoplasm including osteosarcoma. The present study is to clarify the status of abnormalities of this gene in osteosarcoma in China. MATERIALS AND METHODS: Forty-six osteosarcomas were collected from 32 male and 14 female patients aged 20.6 years on average. Eight patients had lung metastasis. Immunohistochemistry, Southern blot and contrast flow cytometry were used for the study. RESULTS: Twenty-seven of 46 (58.7%) osteosarcoma specimens showed strongly positive reaction to the MoAb BP53-12 staining (+2 - +3), which indicated overexpression of P53 protein in osteosarcoma. Contrast study with DNA flow cytometry made on osteosarcoma showed that most of the tumors with strongly positive P53 have higher DNA content than those of negative ones. Alterations of the restriction pattern of the P53 gene were detected in 4 of 20 osteosarcomas in the Hind III group and 3 of 24 in the Eco R I group. Three of them were part or whole deletion of the gene and five of them had extraband which indicated rearrangement of the gene. CONCLUSIONS: The results of this study showed that overexpression of P53 oncoprotein is one of the most frequent genetic changes in osteosarcoma and P53 oncoprotein expression analysis could be a prognostic parameter in osteosarcoma. P53 gene abnormalities play an important role in the development of transformation and proliferation of osteosarcoma cells.

Adult↗
PubMed1996

[Ankylosing spondylitis and heterogenity of HLA-B27 in Chinese].

HLA-B27 represents a family of closely related antigens. More than six alleles differing in limited number of nucleotide substitution had been described (B2701-B2706). We subtyped HLA-B27 in 76 patients with ankylosing spondylitis (AS) and 1200 Chinese healthy persons of Han nationality. Polymerase chain reaction was designed to amplify specific regions for class I (exon 2 and 3). Amplified sequences were tested with eight sequence-specific oligonucleotides to distinguish all HLA-B27 subtypes. The results showed: the HLA-B27 was closely related with AS and at least four subtypes existed in Chinese patients. B2704 was the most common subtype occurring in 54.8% and 50.85% respectively in HLA-B27 positive AS patients and healthy controls. The main HLA-B27 subtypes in the HLA-B27 positive patients distributed in similar proportion to that of HLA-B27 positive healthy controls (P > 0.1). We believe that the above results imply that the prevalences of the various subtypes of HLA-B27 vary in different races. The HLA-B27 specific residues that are shared by the subtypes might be involved in the pathogenesis of AS.

Alleles↗
PubMed1995

[A preliminary study on the inhibitory action of target-primaqine on the exoerythrocytic forms of Plasmodium yoelii yoelii].

Target-primaquine (TPQ)--the primaquine entrapped by galactosylneoglycoalbumin (G-NGA), was given intravenously (iv) to Wistar rats 2 h after sporozoite inoculation. The sporozoite viability (SPV) of TPQ 20 mg/kg group was revealed to be 1.2% 42 h after inoculation, which showed a decline of about 6% as compared to the control; besides, degeneration or retardation of development was present in 90% of EEF. In TPQ 10 mg/kg and PQ 20 mg/kg groups, the SPV were 2.8% and 5.0%, respectively, showing drops by 15% and 26% as compared with that of the control. Degeneration or retardation in development was also visible in about half of the EEF. In mice which were treated iv with TPQ 10 mg/kg or PQ 20 mg/kg 2 h after sporozoite inoculation, the prepatent periods were delayed markedly as compared with that of the control. Parasitemia did not appear in 2 mice in 10 mg/kg TPQ group further indicated the effectiveness of the drug. The results suggest that the anti-EEF effect of TPQ is apparently more promising than that of PQ.

Albumins↗
PubMed1995

[Chromosome study on giant cell tumor of bone].

Chromosome study was made in 30 specimens of giant cell tumor of bone (GCT) and osteosarcoma (OS). In 15 tumors, karyotypes were satisfactorily made for chromosome analysis, including 13 GCTs, one OS and one cell-line of same. The karyotypes of all cells were recognized and described according to the international system for human cytogenetic nomenclature. Karyotype analysis showed that GCT differs from OS both in numerical chromosomal aberrations and in structural chromosomal aberrations. The number of chromosome of GCT concentrated on diploid or subdiploid, with the exception of some superdiploid, while that of OS concentrated on superdiploid or subtriploid. Terminal deletion of chromosome was the most common cytogenetic event in GCT. This resulted in telomere-to-telomere translocations and dicentric chromosomes. Eight of the thirteen successfully analyzed GCT specimens demonstrated telometric fusion or dicentric chromosomes. Superdiploid karyotype was found in six GCTs. Contrast study with DNA flow cytometry showed that the numerical aberrations were consistent with DNA content of GCT. The other structural chromosomal aberrations were ring chromosome, marker chromosome and double minute chromatin bodies etc. The correlation between the chromosome changes and prognosis in GCT has not yet been determined, because of the short term of this study. The cytogenetic changes of osteosarcoma were much more complicated. The common chromosome structural aberrations were translocation, deletion, maker chromosome and double minute chromatin bodies etc.

Adult↗
PubMed1995

Three-dimensional structure of CA1 pyramidal cells in rat hippocampus--optical recording of LSM and computer simulation of fractal structure.

The optical recording of three-dimensional (3-D) reconstruction of CA1 pyramidal cells was derived from the studies on the CA1 region of the hippocampus in adult male Wistar rats. The recording was produced by the Confocal Laser Scan Microscope (LSM-10). The attemption was to outline the morphological neural network of CA1 pyramidal cells organization, following the trail of axo-dendritic connections in 3-D spatial distributions among neurons. The fractal structure of neurons with their dendritic and axonal trees using fractal algorithm was noticed, and 2-18 simulated cells were obtained using PC-486 computer. The simulational cells are similar in morphology to the natural CA1 hippocampal pyramidal cells. Therefore, the exploitation of an advanced neurohistological research technique combining optical recording of the LSM-10 and computer simulation of fractal structure can provide the quantitative fractal structural basis for chaosic dynamics of brain.

Animals↗
PubMed1995

[A study on the viability of corneal endothelium in rabbit by dual staining with trypan blue and alizanin red S].

PURPOSE: We study the viability of preserved rabbit corneal endothelium by dual staining with trypan blue and alizanin red S. METHOD: We randomly divided New Zealand white rabbit eyes into four groups, each with 5 eyes. The eye balls were preserved in moist chambers with aqueous remorad and C3F8 temponade for 5, 7, 10 and 14 days. Then we got the corneal Bottons with sclera ring. Isolated corneas were placed with the endothelial side up in a corneal cup, and trypan blue (0.25%) was added drop-wise to cover the endothelium. After 1.5 minutes the stain was poured out. The endothelial layer was then covered with aliznin red S (0.2%) for 1.5 minutes and pouring away the staining reagent. After staining, the corneas were immensec in glutaraldehyde fixative solution for 10 minutes. Finally, the endothelium was examinated and taken photoes with light microscope. RESULTS: Changed cells that have become permeable to trypan blue show deep blue staining of their nuclei in contrast to the unstained condition of normal cells. All the intercellular borders of endothelial cells were purple. The survival rate of the endothelium preserved for 5 and 7 day is more than 95%, for 10 days is 75-80%, and for 14 days about 70%. CONCLUSION: This technique allows a proportion cout of damaged and undamaged cells in the endothelial monolayer, makes it possible to observe their structures clearly and gives advantage to take pathelage photos.

Animals↗
PubMed1995

[Observation of corneal endothelial cells in modified mid-term preservation by scanning electronic microscope].

PURPOSE: To observe the ultramicroscopic structure of corneal endothelium in modified mid-term preservation. METHODS: Eyes of 4 New Zealand rabbits were enucleated. The 4 right eyes and additional 6 human eyes (as experiment group) were treated as follows: Aqueous was drawn off and replaced with equal volume of C3F8 air, then the whole eye was preserved in wet chamber at 4 degrees C, with 2 rabbit eyes being preserved for 7 days. 1 for 10 days and 1 for 14 days, and 6 human eyes for 0, 3, 5, 7, 10 and 14 days respectively. Corneas with 1 mm scleral ring of the 4 rabbit eyes (control group) were derived and preserved in Optisol nutrients at 4 degrees C for the same period of time. Corneas of all eyes were examined by scanning electronic microscope. RESULTS: For rabbit eyes, slight edema was found in the cornea preserved for 7 days, and loss of surface microvilli and cell lysis were found in those preserved for 10 and 14 days. For human eyes, no significant change was found in cornea preserved for 7 days, and different changes were found in those preserved longer. CONCLUSION: No significant change was found in cornea endothelium preserved by this method for 7 days.

Animals↗
PubMed1994

Hepatitis B virus precore mutation and fulminant hepatitis in the United States. A polymerase chain reaction-based assay for the detection of specific mutation.

Hepatitis B virus (HBV) variants with precore mutation(s) resulting in the absence of HBeAg production have been associated with the occurrence of fulminant hepatitis in Japan, Israel, and southern Europe, where the prevalence of this HBV strain appears common. In areas such as United States, where HBV infection is not endemic, the role of this mutant virus in fulminant hepatitis is unknown. We developed an amplification refractory mutation detection system to detect specifically the presence of the G to A mutation at nucleotide position 1898, which is the most frequently observed mutation resulting in a precore stop codon. In addition, this method provided a quantitative measurement of the relative ratio of one strain to the other. Using this system, we tested HBV strains for the presence of the stop codon mutation in sera from 40 cases of fulminant hepatitis B occurring in the United States. Serum HBV DNAs from 28 patients were analyzed successfully. A mixture of wild-type and mutant strains in various ratios were observed in 15 patients, wild type exclusively in 11, and mutant exclusively in 2. Four of these patients had undergone liver transplantation for HBV-associated cirrhosis and developed fulminant HBV-associated hepatitis after transplantation. Pre- and posttransplant serum samples from one patient were analyzed: a mixture of wild-type and mutant HBV strains was detected in both samples. Our study demonstrated that both wild-type and mutant HBV strains are associated with fulminant hepatitis, and that in some patients in the United States, factors other than precore mutations contribute to the development of fulminant hepatitis.

Adolescent↗
PubMed1994

[Penetrating keratoplasty for bullous keratopathy].

A retrospective review for bullous keratopathy in our hospital from 1985 to 1992 was studies. Among the cases with bullous keratopathy, 14 were performed with antiglaucoma operation and cataract extraction, 12 that experienced a contusion or penetrating trauma history underwent cataract operation. IOL implantation seen in 3 patients, 4 cases were associated with vitreous contact to cornea after cataract extraction, the other 4 cases had advanced glaucoma. Besides, there were 1 case of Fuch's endothelium dystrophy, ICE syndrome and severe herpes simplex keratitis, respectively. The preoperation visual acuity of them was all less than finger count. The follow-up was 3 months to 5 years. The results showed the grafts of 28 cases (70%) were clear, 7 cases (17.5%) semi-clear, 5 cases (12.5%) opaque. Postoperatively, all of the patients escaped from the pain and 22 cases achieved a visual acuity of 0.02-0.7. Some good advice in treatment of bullous keratopathy were proposed.

Adolescent↗
PubMed1993

Different responses to opioids measured in terminals and somas of Edinger-Westphal neurons.

Neurotransmitter receptors on the axon terminals of a neuron can be located a considerable distance away from comparable receptors on the cell body or dendrites of the same neuron. We examined the effects of activating either nerve terminal receptors or those located on or near the somas of chick Edinger-Westphal neurons. Cell body responses were measured via intracellular recording in a brain slice preparation. To measure nerve terminal responses, intracellular recordings were obtained from the large, calyciform nerve endings in intact ciliary ganglia, which emanate from neurons of the lateral Edinger-Westphal nucleus. Cell bodies of Edinger-Westphal neurons responded to leucine-enkephalin with a dose-dependent hyperpolarization that was associated with a decrease in input resistance. In spontaneously active Edinger-Westphal somas, leucine-enkephalin caused marked inhibition of suprathreshold and subthreshold activity, indicating that, as with a number of other central neurons, the major effect of opioids was to reduce excitability. The response to opioids was sensitive to naloxone (1 microM) and was a direct effect, since it was not blocked by either 0.5 microM tetrodotoxin or 100 microM cadmium. More selective mu ([D-Ala2, N-Me-Phe4, Gly5-ol]-enkephalin) and delta ([D-Ser2]-leucine-enkephalin-Thr and [D-Pen2,5]-enkephalin) opioid agonists produced effects similar to those of leucine-enkephalin. Opioids produced strikingly different effects in the nerve terminals of Edinger-Westphal neurons, where the major effect was a depolarization associated with a decrease in input resistance. The effects of opioids in the terminals were reduced in a low sodium buffer, indicating that they were dependent on the presence of extracellular sodium.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1993

[Lamellar keratoplasty for treatment of corneal dermoid].

The results of lamellar keratoplasty for treatment of 53 cases with corneal dermoid were analysed. The visual acuity of postoperation remained or was improved in 79.5% of the cases. Keratometry measured in 12 eyes after surgery showed the corneal curvature remained unchanged in 7 eyes, was reduced in 2 eyes, and increased in 3 eyes. The astigmatism of cornea was not changed or decreased in 6 eyes. Three eyes got increased astigmatism less than 0.5D, the other 3 eyes respectively 1D, 1.5D and 4.4D. The refractive states estimated by photorefraction in 7 eyes showed there was no changed astigmatism in 3 eyes. One eye decreased 2.5D and three eyes respectively increased 0.5 D, 1.0D and 2.0D. Indication and time of surgery for corneal dermoid were also discussed.

Adolescent↗
PubMed1990

An improved method to study the impact of pesticide sprays on small song birds.

Four test groups of small songbirds (Zebra Finch, Poephila guttata) were sprayed in a chamber with varying concentrations of fenitrothion. Exposure levels were assessed by monitoring air concentrations, deposits of the active ingredient (AI) on glass plates and droplets/cm2 on Kromekote cards. All indices of exposure were linearly correlated and the mean AI deposit on glass plates for the four groups tested with equivalent to 38, 51, 139 and 255 g/ha or 14%, 18%, 50% and 91% of the highest permissible emitted rate for broadscale forest spraying in Canada. Significant depression in body weights and brain acetylcholinesterase levels were noted only for the highest exposure group. Fenitrothion residues in blood were detectable only at the highest exposure level, and in liver at the two higher levels. Carcass and feather residues were much higher than those in blood and liver, and were detectable at all exposure levels but the residues did not increase linearly with exposure. For one of the spray groups, we were able to compute an equivalent acute oral dose based on matching acetylcholinesterase inhibition.

Acetylcholinesterase↗
PubMed1990

Penetrating keratoplasty combined with cataract extraction.

The authors report the results of penetrating keratoplasty combined with cataract extraction in 50 cases. The rate of transparent grafts was 62% after an average follow-up of 19 months. 60% of the patients restored their vision to 0.1 and better. The rate of transparent grafts and visual improvement did not correlate with the mode of cataract extraction; however, the extracapsular procedure had less vitreous during operation than the intracapsular modality did. The authors recommend that the combined operation be adopted for patients with corneal opacity and cataract, and preferably using the extracapsular mode.

Adolescent↗
PubMed1990

[Observations on neuronal activity in frontal cortex and EMGs in monkeys during performing noxious and innocuous heat discrimination GO/NO-GO task].

To study the functional implication of neuronal responses in frontal cortex to noxious and innocuous heat stimuli, experiments were carried out on two monkeys (Macaca mulatta) during performing a delayed discrimination GO/NO-GO task. The animals were trained to hold a lever for at least 3 s in the response period when an innocuous heat stimulus had been applied to the forearm in the cue period, or release it within 1 s with a noxious one. After a criterion of 90% of correct responses in 3 successive days was reached, single neuronal activity was recorded from the frontal cortex along with EMGs from six muscles in both arms. Of 142 task-related neurons recorded, 87 (66.4%) were related to heat, 34 to visual, and 21 to both visual and heat stimuli. Among the heat-related neurons, 22 were responsive to noxious heat, 18 to innocuous heat, and 47 to both. Of the neurons responding to both noxious and innocuous heat stimuli, 4 neurons showed changes in discharge rates, depending on the type of stimuli. In most cases, muscular activities just appeared at the moment of lever pressing and/or releasing in m. extensor digitorium communis, m. flexor carpi ulnaris and m. flexor carpi radialis of the performing arm. No regular muscular activities appeared in other muscles and in other periods of the task. The result showed that the neuronal responses in frontal cortex elicited by heat stimuli in the cue period were not related directly to the initiation and modulation of behaviours.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Integrated Academic Information Management Systems (IAIMS). Part III. Implementation of Integrated Information Services. Integration across institutions: IAIMS extended.

The technologies contributing to today's information world are profound. Electronic technologies are transforming the way we handle information and the medium used to pursue knowledge. What once seemed beyond reach--that computers, communications, information, and knowledge systems could be merged harmoniously to transmit information via networks--is reality today. The Integrated Academic Information Management System (IAIMS) approach for transfer of biomedical information within a medical center also offers opportunities for networks across institutional lines. The tradition of cooperation and resource sharing among libraries makes them logical facilitators of the emerging, universal information environment. The authors present a course of action based on visions of a new era, realities of the present, and strategies for the future.

Academic Medical Centers↗
PubMed1982

DNA-dependent RNA polymerases for Schneider 2-L cells of Drosophila. I. Preliminary characterization.

The DNA-dependent RNA polymerases of Schneider 2-L cells of Drosophila melanogaster are described. These cells contain five readily detectable forms of this enzyme, polymerases Ia, Ib, IIIa, II, and IIIb, which elute from DEAE-Sephadex at 0.08, 0.12, 0.15, 0.20, and 0.22 M ammonium sulfate, respectively. RNA polymerases IIIa and IIIb, which each constitute about 5-10% of the total RNA polymerase activity in Drosophila embryos, are found to constitute 30 and 10%, respectively, of the total polymerase activity in cultured cells. The two form III polymerases are further characterized by in vitro response to divalent cations and ionic strength, template utilization, and sensitivity to alpha-amanitin. Verification of the class III designation of these two polymerases is provided by their sensitivity to only very high levels of alpha-amanitin (50% inhibition at approximately 800 micrograms/ml), their 10-fold greater activity on poly[d(A-T)], and their elution from DEAE-cellulose at lower ionic strengths that from DEAE-Sephadex.

Ammonium Sulfate↗