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Biomedical subjects

H Feng

Publications and source records attributed to H Feng.

At least 19 recordsLinked to original sources
PubMed2007

Anomalous intracranial venous drainage associated with basal ganglia calcification.

We describe the neuroradiologic findings in a 7-year-old boy with anomalous intracranial venous drainage and cerebral calcification. CT scans demonstrated that his scalp mass was a plexus of scalp veins filled through the emissary foramen, and there were cerebral calcifications. Angiography revealed bilateral sigmoid sinus atresia with most of the intracranial venous drainage via the prominent mastoid emissary veins into dilated scalp vein. The possible relationship between cerebral calcification and anomalous intracranial venous drainage is discussed.

Basal Ganglia Diseases↗
PubMed2006

Protein serine/threonine phosphatase-1 dephosphorylates p53 at Ser-15 and Ser-37 to modulate its transcriptional and apoptotic activities.

We have previously demonstrated that the serine/threonine protein phosphatase-1 (PP-1) plays an important role in promoting cell survival. However, the molecular mechanisms by which PP-1 promotes survival remain largely unknown. In the present study, we provide evidence to show that PP-1 can directly dephosphorylate a master regulator of apoptosis, p53, to negatively modulate its transcriptional and apoptotic activities, and thus to promote cell survival. As a transcriptional factor, the function of p53 can be greatly regulated by phosphorylation and dephosphorylation. While the kinases responsible for phosphorylation of the 17 serine/threonine sites have been identified, the dephosphorylation of these sites remains largely unknown. In the present study, we demonstrate that PP-1 can dephosphorylate p53 at Ser-15 and Ser-37 through co-immunoprecipitation, in vitro and in vivo dephosphorylation assays, overexpression and silence of the gene encoding the catalytic subunit for PP-1. We further show that mutations mimicking constitutive dephosphorylation or phosphorylation of p53 at these sites attenuate or enhance its transcriptional activity, respectively. As a result of the changed p53 activity, expression of the downstream apoptosis-related genes such as bcl-2 and bax is accordingly altered and the apoptotic events are either largely abrogated or enhanced. Thus, our results demonstrate that PP-1 directly dephosphorylates p53, and dephosphorylation of p53 has as important impact on its functions as phosphorylation does. In addition, our results reveal that one of the molecular mechanisms by which PP-1 promotes cell survival is to dephosphorylate p53, and thus negatively regulate p53-dependent death pathway.

Amino Acid Substitution↗
PubMed2006

Intramedullary cervical tuberculoma.

STUDY DESIGN: Case report. OBJECTIVE: To report a rare lesion of intramedullary cervical tuberculoma. SETTING: Department of Neurosurgery, Southwest Hospital, Third Military Medical University, Chongqing, The People's Republic of China. CASE REPORT: A 15-year-old boy presented with pain in the neck and shoulder. Examination showed mild left hemiplegia and pinprink hyperalgesia on the left side up to C3 level. Chest X-ray and CT scan showed patch and dot lesions indicating old tuberculous lesions and MRI showed a ring-enhancing intramedullary lesion at C3/4 level. Tuberculoma resection and antituberculous therapy was given. There was satisfactory recovery clinically. CONCLUSION: Intramedullary cervical tuberculoma is a rare, coexisting systemic tuberculosis and MRI scan helps in obtaining a correct diagnosis; combining surgery with anti-tuberculosis therapy is the treatment of choice.

Adolescent↗
PubMed2006

Photodynamic therapy increases brain edema and intracranial pressure in a rabbit brain tumor model.

The objective of this study was to evaluate the effect of a single photodynamic therapy (PDT) on brain edema and intracranial pressure (ICP) in a rabbit model of brain tumor. A total of 57 adult New Zealand rabbits were assigned to 3 groups: the PDT group, the tumor group, and the tumor plus PDT group. Rabbits in the PDT group (n = 9) received PDT but no tumor implantation; rabbits in the tumor group (n = 18) received VX2 carcinoma implantation but no PDT; rabbits in the tumor plus PDT group (n = 30) received tumor implantation with subsequent PDT 16 days later. Brain edema and ICP levels were then evaluated. We found that ICP in the PDT group was 7.43 +/- 0.50 mmHg. After tumor implantation, ICP increased rapidly (18.43 +/- 1.10 mmHg, 21 days later). PDT alone did not increase ICP, but compared with that in the tumor group, ICP increased significantly in the tumor plus PDT group (9.55 +/- 1.32 vs. 13.31 +/- 1.13 mmHg, p < 0.01) 24 hours after treatment. Brain water content in the tumor group increased rapidly after tumor implantation. PDT again increased perineoplastic brain edema 24 hours after treatment (81.09 +/- 0.97% vs. 78.32 +/- 0.49%, p < 0.01). It should be noted that PDT alone did not induce brain edema. In conclusion, PDT causes transient brain edema and increases ICP in a rabbit brain tumor model.

Animals↗
PubMed2004

Id-I stimulates cell proliferation through activation of EGFR in ovarian cancer cells.

Increased EGFR (epidermal growth factor receptor) expression has been reported in many types of human cancer and its levels are positively associated with advanced cancers. Recently, upregulation of Id-1 (inhibitor of differentiation or DNA binding) protein was found in over 70% of ovarian cancer samples and correlated with poor survival of ovarian cancer patients. However, the molecular mechanisms responsible for the role of Id-1 in ovarian cancer are not clear. The aim of this study was to investigate the effect of Id-1 on ovarian cancer proliferation and its association with the EGFR pathway. To achieve this, we transfected an Id-1 expression vector into three ovarian cancer cell lines and examined cell proliferation rate by flow cytometry and bromodeoxyuridine staining. We found that ectopic Id-1 expression led to increased cell proliferation demonstrated by increased BrdU incorporation rate and S-phase fraction. The Id-1-induced cell growth was associated with upregulation of EGFR at both transcriptional and protein levels. In contrast, inactivation of Id-1 through transfection of an Id-1 antisense vector resulted in downregulation of EGFR. Our results indicate that increased Id-1 in ovarian cancer cells may promote cancer cell proliferation through upregulation of EGFR. Our findings also implicate that Id-1 may be a potential target for the development of novel strategies in the treatment of ovarian cancer.

Blotting, Western↗
PubMed2004

Ventral brainstem enterogenous cyst: an unusual location.

Enterogenous cysts mostly locate in the spinal canal and have only rarely been reported in an intracranial site. We report a case of enterogenous cyst in the ventral to brainstem. The 45-year-old woman presented with paroxysmal headache and diplopia. A CT scan and MRI revealed a cystic clival mass from midbrain to medulla. Subtotal resection was performed using a sub-temporal approach and the patient made a good recovery. Pathological examination revealed that the lesion was a typical enterogenous cyst.

Brain Diseases↗
PubMed2003

Fertilization abnormalities following human in vitro fertilization and intracytoplasmic sperm injection.

Fertilization abnormalities are commonly encountered following in vitro fertilization. The widespread introduction of assisted fertilization methods has rapidly led to a changes in both the incidence and types of these aberrations. Such abnormalities can be identified by careful morphological evaluation at the early zygote stage, of pronuclei as well as of polar body formation, and may be confirmed by cytogenetic assessment. The recognition and understanding of fertilization abnormalities have led to the development of novel techniques aimed at preventing them, as well as recent bold attempts at correction. Removal of one pronucleus may allow some triploid embryos to revert to a normal diploid stage. These new developments should provide insight into the understanding of parthenogenesis, androgenesis, and gynogenesis in the human. Microsc. Res. Tech. 61:358-361, 2003.

Chromosome Aberrations↗
PubMed2003

Nitric oxide alleviates oxidative damage in the green alga Chlorella pyrenoidosa caused by UV-B radiation.

The effect of ultraviolet-B radiation (UV-B; 280-320 nm) on induction of nitric oxide was estimated in the suspensions of green alga Chlorella pyrenoidosa with or without the NO scavenger N-acetyl-L-cysteine, and reductants such as 1,4-dithiothreitol, glutathione (reduced form), and ascorbic acid. Exogenously added sodium nitroprusside (NO donor), glutathione, 1,4-dithiothreitol, and ascorbic acid were able to prevent chlorophyll loss mediated by UV-B. Addition of NO to algal suspensions irradiated by UV-B increased the activity of catalase and superoxide dismutase but lowered the activity of phenylalanine ammonia-lyase. UV-B thus appears to be a strong inducer of NO production, exogenously added NO and reductants protecting the green alga against UV-B-induced oxidative damage.

Acetylcysteine↗
PubMed2003

Novel identification of a four-base-pair deletion mutation in PITX2 in a Rieger syndrome family.

Rieger syndrome is one of the most serious causes of tooth agenesis. Mutations in the PITX2, FOXC1, and PAX6 genes have been associated with Rieger syndrome. We have studied a three-generation Chinese family affected with Rieger syndrome and showing prominent dental abnormalities. Mutational screening and sequence analysis of the PITX2 gene revealed a previously unidentified four-base-pair deletion of nucleotides 717-720 in exon 5 in all affected members. The mutation causes a frame shift after Thr44, the 7th amino acid of the homeo-domain, and introduces a premature stop codon in the gene sequence. This deletion is the first unquestionable loss-of-function mutation, deleting all the functionally important parts of the protein. Our novel discovery indicates that the oligodontia and other phenotypes of Rieger syndrome observed in this family are due to this PITX2 mutation, and these data further support the critical role of PIXT2 in tooth morphogenesis.

Adolescent↗
PubMed2001

Dredged material decontamination demonstration for the port of New York/New Jersey.

Management of contaminated dredged material is a significant challenge in the Port of New York and New Jersey as a result of more stringent regional ocean placement regulations with escalating costs for upland placement. One component of an overall management plan can be the application of a decontamination technology followed by creation of a product suitable for beneficial use. This concept is the focus of a project now being carried out by the US Environmental Protection Agency, Region 2, the US Army Corps of Engineers, New York District, the US Department of Energy, Brookhaven National Laboratory, and regional university groups that have included Rensselaer Polytechnic Institute, Rutgers University, New Jersey Institute of Technology, and Stevens Institute of Technology. The project has progressed through phased testing of commercial technologies at the bench scale (15 liters) (Marcor, Metcalf & Eddy, Gas Technology Institute, Westinghouse Science & Technology, BioGenesis, International Technology, and BioSafe) and pilot-scale (1.5-500m(3)) (BioGenesis, Gas Technology Institute, and Westinghouse Science & Technology) levels. The technologies developed by Gas Technology Institute and BioGenesis are now going forward to commercial demonstration facilities that are intended to treat from 23000 to 60000m(3) of dredged material during their first operational period in 2001-2002. Beneficial use products are soils and cement. Treatment costs for the final commercial facilities are estimated at US$ 39 per m(3). Selection of the technologies was made based on the effectiveness of the treatment process, evaluation of the possible beneficial use of the treated materials, and other factors. Major elements of the project are summarized here.

Conservation of Natural Resources↗
PubMed2001

[The effect of focal mild hypothermia on the temperature gradient in brain].

OBJECTIVE: Through studying the effect of focal mild hypothermia on the distribution of brain temperature, which reveals the function that the semi-conductor refrigerator apparatus decreases the temperature to mild hypothermia level during therapeutic time window. METHODS: Directly measure the intracerebral temperatures of different regions when we refrigerator the brains of piglets. According to the results of the measure and the formula of heat conduction, we can establish the three-dimensional space and the temperature gradient mathematical model of pig brain. RESULTS: (1) The theoretical data deduced by function model fit very well to the laboratory data, absolutely average error is 0.15 degree C. (2) After 17 minutes of the piglet refrigerated at 2-10 degrees C, thalamic and putamen temperature decreases to 32-34 degrees C. CONCLUSION: Apply the regional semi-conductor refrigerator apparatus to decrease the brain temperature to mild hypothermia level during therapeutic time window and find the function relationship between refrigerator temperature and brain temperatures so as to provide the theoretical proof for clinical application of focal mild hypothermia.

Animals↗
PubMed2001

Stressed apoptotic tumor cells express heat shock proteins and elicit tumor-specific immunity.

In attempting to develop effective anticancer immunotherapies, the relative ability of apoptotic cells to induce an immune response remains an important but controversial consideration. A novel gene-transfer approach was used by which rapid induction of pure apoptosis can be selectively achieved in a transfected tumor cell population following exposure to a semisynthetic dimerizing ligand, AP20187. Inoculation of BALB/c mice with apoptotic and viable 12B1-D1 leukemia cells, at a 12:1 ratio subcutaneously, led to early tumor growth. Heat stress up-regulated the expression of membrane heat shock proteins (HSP72 and HSP60) on apoptotic 12B1-D1 cells, and stressed apoptotic cells were capable of generating a T-cell-mediated specific antitumor response. Pulsing of stressed apoptotic leukemia cells onto syngeneic dendritic cells resulted largely in rejection of coinjected viable 12B1-D1 cells. Mice rejecting the primary 12B1-D1 inoculum were immune to the same but not to a different leukemia challenge. Our findings indicate that tumor immunogenicity is dependent on whether cells are stressed before apoptosis induction and suggest that the immune system is capable of distinguishing between stressed and nonstressed cells undergoing programmed cell death. (Blood. 2001;97:3505-3512)

Animals↗
PubMed2001

Replacement of segmental bone defects using porous bioceramic cylinders: a biomechanical and X-ray diffraction study.

A porous ceramic material [hydroxyapatitetricalcium phosphate (HA-TCP)] was implanted in the femora of 30 dogs to investigate the possibility of using this material to repair segmental bone defects. A bone segment, 1.5 cm in length, was removed from the diaphysis of one femur in each dog to create the defect. Cylinders of corresponding size were inserted into the defects. The animals were divided into three groups with recovery times of 2 months, 4 months, and 6 months, respectively. The implants were harvested and subjected to biomechanic tests (bending strength) and X-ray diffraction analysis. The bending strengths of the implant construct increased gradually over time postoperatively. The values of strength for the three different time groups had significant variations (p < 0.05). The X-ray diffraction analysis indicated that the peaks of the TCP included in the cylinders decreased in intensity after implantation and tended to be similar to those of natural bone by 6 months after operation. Conversely, the peaks for the HA had fewer changes compared with preimplantation values. Based on the results of this experiment it was concluded that the porous HA-TCP ceramic cylinders have potential for repair of segmental bone defects if assisted by adequate stabilizing fixtures during the early postoperative period.

Animals↗
PubMed2001

Mapping transient, randomly occurring neuropsychological events using independent component analysis.

The feasibility of mapping transient, randomly occurring neuropsychological events using independent component analysis (ICA) was evaluated in an auditory sentence-monitoring fMRI experiment, in which prerecorded short sentences of random content were presented in varying temporal patterns. The efficacy of ICA on fMRI data with such temporal characteristics was assessed by a series of simulation studies, as well as by human activation studies. The effects of contrast-to-noise ratio level, spatially varied hemodynamic response within a brain region, time lags of the responses among brain regions, and different simulated activation locations on the ICA were investigated in the simulations. Component maps obtained from the auditory sentence-monitoring experiments in each subject using ICA showed distinct activation in bilateral auditory and language cortices, as well as in superior sensorimotor cortices, consistent with previous PET studies. The associated time courses in the activated brain regions matched well to the timing of the sentence presentation, as evidenced by the recorded button-press response signals. Methods for ICA component ordering that may rank highly the components of primary interest in such experiments were developed. The simulation results characterized the performance of ICA under various conditions and may provide useful information for experimental design and data interpretation.

Adult↗
PubMed2001

Dendritic-cell-peptide immunization provides immunoprotection against bcr-abl-positive leukemia in mice.

Chronic myelogenous leukemia (CML) is a clonal disorder characterized by proliferation of cells that possess the bcr-abl fusion gene resulting in the production of one of two possible chimeric 210-kDa tyrosine kinase proteins. Since these chimeric proteins are expressed only in leukemic cells they have the potential to serve as tumor-specific antigens for cytotoxic T lymphocytes (CTL). Using the 12B1 murine leukemia cell line, derived by retroviral transformation of BALB/c bone marrow cells with the bcr-abl (b3a2) fusion gene, we have demonstrated that intravenous inoculation of 12B1 cells into BALB/c mice results in a disseminated acute leukemia analogous to human CML in blast crisis. Histological sections of liver and spleen and polymerase chain reaction analysis of peripheral blood, bone marrow, liver, spleen and lymph nodes confirmed the presence of bcr-abl+ leukemia cells in these murine tissues, while Western blot data demonstrated the expression of the fusion protein in 12B1 cells. Immunization of mice with dendritic cells (DC) loaded with the synthetic bcr-abl chimeric nonapeptide, GFKQSSKAL, led to a 150 times higher frequency of bcr-abl-specific CTL precursors in the spleen than in mice immunized with peptide alone. In vitro re-stimulation of DC-peptide-primed splenocytes resulted in substantial secretion of interferon gamma and augmented cytolytic activity against 12B1 targets. Finally, vaccination with peptide-loaded DC significantly prolonged survival of BALB/c mice that were challenged with 12B1 leukemia. The capacity to generate bcr-abl-specific CTL in vivo by DC-based immunization may have clinical implications in the treatment of CML.

Animals↗
PubMed2001

Fourier-transform Raman and infrared spectroscopic analysis of dipyrrinones and mesobilirubins.

The Fourier-transform Raman (FT-Raman), infrared (FT-IR), and UV-visible absorption spectra of four dipyrrinones and two mesobilirubins have been investigated in the solid state and in CH2Cl2 solutions. A detailed spectral analysis, assignment and discussion of these spectra are presented. The bands at 1735-1738, 1691-1707 and 1359-1377 cm(-1) which were assigned to the stretching vibrations of the C-O-C and C-O-H and symmetric deformation of C-H bonds, respectively, can act as a marker to distinguish the compounds of this class. The striking differences between the spectra of the compounds suggest that mesobilirubin XIIIalpha is tending to adopt as ridge-tile conformation, rather than linear conformation.

Bilirubin↗