Biomedical subjects

Feng Feng

Publications and source records attributed to Feng Feng.

At least 19 recordsLinked to original sources

PubMed2026

PtoeIF5A1: A Pleiotropic Regulator of Development, PCD, and Salt Tolerance in Populus tomentosa.

Eukaryotic translation initiation factor 5A (eIF5A) is a highly conserved protein family unique to eukaryotes, yet its functional characterization in woody plants remains limited. In this study, we identified four eIF5A genes (PtoeIF5A1-PtoeIF5A4) from the genome of Populus tomentosa, a fast-growing tree species indigenous to China, and characterized their expression patterns and functional roles through bioinformatics analysis, quantitative real-time PCR, stable overexpression in Arabidopsis thaliana, and transient expression in Nicotiana benthamiana leaves. Our results demonstrated that all PtoeIF5A proteins contain a conserved OB-fold domain and multiple phosphorylation sites, with PtoeIF5A1 showing predominant expression in roots and secondary xylem. Functional assays revealed that PtoeIF5A1 overexpression accelerated inflorescence stem elongation and early flowering in Arabidopsis, induced visible chlorosis and programmed cell death (PCD) in tobacco leaves, and significantly enhanced salt tolerance under NaCl treatment. Collectively, these findings establish PtoeIF5A1 in poplar as a pleiotropic regulator integrating developmental cues, programmed cell death, and stress responses; and as a valuable genetic resource for breeding stress-resilient woody plants.

Populus tomentosa↗

PubMed2006

Estrogen transactivates EGFR via the sphingosine 1-phosphate receptor Edg-3: the role of sphingosine kinase-1.

The transactivation of enhanced growth factor receptor (EGFR) by G protein-coupled receptor (GPCR) ligands is recognized as an important signaling mechanism in the regulation of complex biological processes, such as cancer development. Estrogen (E2), which is a steroid hormone that is intimately implicated in breast cancer, has also been suggested to function via EGFR transactivation. In this study, we demonstrate that E2-induced EGFR transactivation in human breast cancer cells is driven via a novel signaling system controlled by the lipid kinase sphingosine kinase-1 (SphK1). We show that E2 stimulates SphK1 activation and the release of sphingosine 1-phosphate (S1P), by which E2 is capable of activating the S1P receptor Edg-3, resulting in the EGFR transactivation in a matrix metalloprotease-dependent manner. Thus, these findings reveal a key role for SphK1 in the coupling of the signals between three membrane-spanning events induced by E2, S1P, and EGF. They also suggest a new signal transduction model across three individual ligand-receptor systems, i.e., "criss-cross" transactivation.

Cell Line, Tumor↗

PubMed2006

A disorganized innervation of the inner ear persists in the absence of ErbB2.

ErbB2 protein is essential for the development of Schwann cells and for the normal fiber growth and myelin formation of peripheral nerves. We have investigated the fate of the otocyst-derived inner ear sensory neurons in the absence of ErbB2 using ErbB2 null mutants. Afferent innervation of the ear sensory epithelia shows numerous fibers overshooting the organ of Corti, followed by a reduction of those fibers in near term embryos. This suggests that mature Schwann cells do not play a role in targeting or maintaining the inner ear innervation. Comparable to the overshooting of nerve fibers, sensory neurons migrate beyond their normal locations into unusual positions in the modiolus. They may miss a stop signal provided by the Schwann cells that are absent as revealed with detailed histology. Reduction of overshooting afferents may be enhanced by a reduction of the neurotrophin Ntf3 transcript to about 25% of wild type. Ntf3 transcript reductions are comparable to an adult model that uses a dominant negative form of ErbB4 expressed in the supporting cells and Schwann cells of the organ of Corti. ErbB2 null mice retain afferents to inner hair cells possibly because of the prominent expression of the neurotrophin Bdnf in developing hair cells. Despite the normal presence of Bdnf transcript, afferent fibers are disoriented near the organ of Corti. Efferent fibers do not form an intraganglionic spiral bundle in the absence of spiral ganglia and appear reduced and disorganized. This suggests that either ErbB2 mediated alterations in sensory neurons or the absence of Schwann cells affects efferent fiber growth to the organ of Corti.

Animals↗

PubMed2006

[Comparison of multi-slice spiral CT and magnetic resonance imaging in evaluation of the un-resectability of blood vessels in pancreatic tumor].

OBJECTIVE: To compare the values of multi-slice spiral CT (MSCT) and magnetic resonance imaging (MRI) in evaluating the un-resectability of blood vessels in pancreatic tumor. METHODS: Images obtained from MSCT and MRI of pancreas in 14 patients with pancreatic cancer were retrospectively reviewed. MSCT scanning included arterial phase, pancreatic-portal phase, and delay-phase. MRI scanning included fat-suppressed T2WI, dual-echo T1WI, and fat-suppressed T1WI before and after injection of contrast (arterial phase, pancreatic-portal phase, delay-phase, and late delay phase). Seven patients received operations within two weeks after the examinations. The staging of peripancreatic blood vessels in MSCT and MRI images was evaluated and compared. The veracity of MSCT and MRI in assessing the un-resectability of peripancreatic blood vessels was calculated and compared according to the findings in operation. RESULTS: All the tumors were observed in MSCT and MRI images. Statistical difference existed in staging of peripancreatic blood vessels and in evaluating their un-resectability between MSCT and MR (P < 0.05). The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of the un-resectability assessed by MSCT were 77.8%, 95%, 91.8%, 77.8%, and 95%, respectively, and those assessed by MR were 66.7%, 90%, 85.7%, 60%, and 92.3%, respectively. CONCLUSION: Dynamic MSCT is better than dynamic MR to some extent in evaluating the un-resectability of peripancreatic blood vessels in pancreatic tumor.

Aged↗

PubMed2006

[Vertical distribution of species of nitrogen and phosphorus in the sediments of Lake Donghu].

Vertical distributions of species of nitrogen and phosphorus in the sediments of three sampling sites in Lake Donghu were examined and analyzed. pH was combined to be studied at the same time. The results showed that the pH values in sediments were lower than those in overlying water and decreased with depth. The highest concentration of TN and TP occurred in Station 1, where suffered from heavy domestic sewerage. The lowest concentration of TP and TN presented to Station 2, which is located at the center of Lake Donghu. The concentrations of dissolved ammoniac nitrogen (DAN) and dissolved nitrate nitrogen (DNN) of station 1 were higher than the other stations. In recent years, along with the pollution treatment measures, the concentration of TN and TP in station 1 presented a trend of decline. However, the concentration of TN and TP ascends very fast in station 3 and it has been as high as station 1 on the surface sediments. Although phosphorus is the most restricting nutritious element all the same, the concentration of TN descended greatly in the last two decades because of the combined effect of nitrification, denitrification and phosphorus removing bacteria. As a result, the N/P ratio is only about 3.

China↗

PubMed2006

[Vascularized fibular combined with iliac grafting to repair bone defect after tumor extensive resection for giant cell tumor of bone around knee].

OBJECTIVE: To study the method and effect of the vascularized fibular combined with iliac grafting after the tumor extensive resection for giant cell tumor of the bone around the knee. METHODS: Twenty-five patients with giant cell tumor of the bone around the knee were reviewed, who had been admitted to our hospital from October 1996 to November 2002, including 17 patients undergoing the fibular and iliac transplantation with the vessels anastomosed after the extensive excision of the bone tumor. By the surgically-staged manner of Enneking, all the patients were grouped in the stage of I A; by the Campanacci's radioactive image staging, 11 patients were grouped in stage I, 5 in stage II , and 1 in stage III; by the Jaffe's pathological staging, 9 patients were grouped in stage I, 7 in stage II, and 1 in stage III. Of the patients, 9 were treated by the vascularized fibular combined with iliac grafting in the proximal tibia after the tumor extensive resection, and 8 were treated by the distal femur reconstruction by the operation. The following items were also analyzed: postoperative infection, growth of the bone graft, rate of local recurrence, tumor metastasis, and bone death. The function of the knee joint was evaluated. RESULTS: According the follow-up of the 17 patients for 26-87 months (mean, 54 months), all the bone graft healed well within 75-120 days (mean, 93 days) after operation. Two patients had a local recurrence and 3 had a mildly-narrowed joint. The flexion and extension function of the knee joint recovered, with a range of motion of the reconstructed distal femur of 80 degrees-105 degrees (mean, 96 degrees) while the proximal tibia had a range of motion of 90-120 degrees (mean, 110 degrees). The functional outcome was excellent in 11 patients, good in 3 patients, fair in 1 patient, and bad in 2 patients, with a total satisfactory rate of 82.4%. CONCLUSION: The vascularized fibular combined with iliac grafting after the tumor extensive resection to treat giant cell tumor of the bone around the knee has advantages of complete resection of the tumor and well-restored or reconstructed structure and function of the knee joint.

Adolescent↗

PubMed2006

[Effects of vasectomy on prostatic histomorphology and cell apoptosis in rats].

OBJECTIVE: To detect the effects of vasectomy on the growth and apoptosis of prostatic tissue cells. METHODS: Forty-five SD rats were divided at random into three groups of fifteen each. Vasectomy (Vsm) model was established by ligating the bilateral vas deferens of the rats in Group A and testosterone propionate and normal saline were subcutaneously injected in those of Groups B and C, respectively. The area percentage of each part in the prostatic tissue was measured with computer-assisted image analysis system. The apoptotic rate was examined with TUNEL. RESULTS: The ratio of stromal area to epithelial plus lumen area in the prostatic tissues in Groups A, B and C were (29.20 +/- 6.85), (39.77 +/- 7.58) and (48.90 +/- 6.49), respectively, and the differences were significant statistically (P all < 0.05). The apoptosis rates in Groups A, B and C were (6.39 +/- 0.84)%, (2.62 +/- 0.57)% and (4.58 +/- 0.93)%, respectively, significantly higher in Group A than in Groups B and C (P all < 0.05). CONCLUSION: Vasectomy may induce interstitium reduction and cell apoptosis in the prostatic tissues of rats, which may help prevent benign prostatic hyperplasia.

Animals↗

PubMed2005

Differential expression of KCNQ4 in inner hair cells and sensory neurons is the basis of progressive high-frequency hearing loss.

Human KCNQ4 mutations known as DFNA2 cause non-syndromic, autosomal-dominant, progressive high-frequency hearing loss in which the cellular and molecular basis is unclear. We provide immunofluorescence data showing that Kcnq4 expression in the adult cochlea has both longitudinal (base to apex) and radial (inner to outer hair cells) gradients. The most intense labeling is in outer hair cells at the apex and in inner hair cells as well as spiral ganglion neurons at the base. Spatiotemporal expression studies show increasing intensity of KCNQ4 protein labeling from postnatal day 21 (P21) to P120 mice that is most apparent in inner hair cells of the middle turn. We have identified four alternative splice variants of Kcnq4 in mice. The alternative use of exons 9-11 produces three transcript variants (v1-v3), whereas the fourth variant (v4) skips all three exons; all variants have the same amino acid sequence at the C termini. Both reverse transcription-PCR and quantitative PCR analyses demonstrate that these variants have differential expression patterns along the length of the mouse organ of Corti and spiral ganglion neurons. Our expression data suggest that the primary defect leading to high-frequency loss in DFNA2 patients may be attributable to high levels of the dysfunctional Kcnq4_v3 variant in the spiral ganglion and inner hair cells in the basal hook region. Progressive hearing loss associated with aging may result from an increasing mutational load expansion toward the apex in inner hair cells and spiral ganglion neurons.

Animals↗

PubMed2005

Diffusion and imaging properties of three new lipophilic tracers, NeuroVue Maroon, NeuroVue Red and NeuroVue Green and their use for double and triple labeling of neuronal profile.

We describe here diffusion and imaging properties of three new lipophilic tracers, NeuroVue Maroon (near infrared), NeuroVue Red and NeuroVue Green. Using pair-wise comparisons between the new dyes and existing dyes (DiI, DiA, DiD, DiO, PKH2, PKH26) applied to the left and the right side of fixed spinal cord preparations, we show that NeuroVue Maroon (excitation maximum 647 nm) surpasses all other dyes in this study in signal to noise ratio. We also present data showing the utility of these new dyes for both double labeling and triple labeling in combination with each other or existing lipophilic tracers. Using mice bearing the PLP-eGFP transgene, we demonstrate that either NeuroVue Maroon or NeuroVue Red can readily be combined with eGFP labeling. Double labeling experiments using NeuroVue Red and eGFP allowed us to demonstrate that every fiber in the neonatal ear is surrounded by developing Schwann cells.

Animals↗

PubMed2005

Comparative study on the inclusion behavior between meso-tetrakis(4-N-ethylpyridiniurmyl)porphyrin and beta-cyclodextrin derivatives.

5,10,15,20-Tetrakis(4-N-ethylpyridiniurmyl)porphyrin (TEPyP) formed 1:1 stoichiometry inclusion complexes with beta-cyclodextrin (beta-CD) and its derivatives including hydroxypropyl-beta-cyclodextrin (HP-beta-CD), sulfobutylether-beta-cyclodextrin (SBE-beta-CD) in basic aqueous solution. The supramolecular system was investigated by the methods of fluorescence, UV-vis absorption spectroscopy, nuclear magnetic resonance (NMR) technique. The inclusion ability of cyclodextrins exhibited remarkable difference for beta-CD, HP-beta-CD and SBE-beta-CD. Association constants as high as K=1.1 x 10(4) M(-1) in the case of HP-beta-CD/TEPyP and 2.0 x 10(5) M(-1) in the case of SBE-beta-CD/TEPyP complexes were determined, whereas a lower value (K=550 M(-1)) was given in the case of beta-CD/TEPyP. The results showed that hydrogen bonding and charge attraction play important roles in the processes of host-guest interaction. The interaction mechanism of inclusion processes could be explained by the analysis of NMR spectroscopy. The supramolecular assembly was formed. beta-CD and HP-beta-CD approached from the primary face of cavities of CDs.

2-Hydroxypropyl-beta-cyclodextrin↗

PubMed2005

Effect of cyclic third components on non-deoxygenated RTP and their potential in developing optical thermometer.

Effect of five cyclic third components, cyclohexane, methylcyclohexane, perfluorocyclohexane, perfluoromethylcyclohexane and adamantane, on cyclodextrin-induced room-temperature phosphorescence (CD-RTP) of 1-bromonaphthalene is studied. It is found that these five compounds can induce intensive RTP, and the enhancement order is as follows: cyclohexane>adamantane>methylcyclohexane>perfluorocyclohexane>perfluoromethylcyclohexane. Dependence of RTP intensity on temperature of these systems shows the potential application in developing optical thermometer.

Cyclization↗

PubMed2005

The mechanical and thermal effects of focused ultrasound in a model biological material.

This paper is motivated by possible medical applications of focused ultrasound in the minimally invasive treatment of a variety of musculoskeletal disorders that are responsive to thermal treatment. A model-based analysis of the interaction of high-intensity focused ultrasound with biological materials is carried out in an effort to predict the path of the sound waves and the temperature field in the focal region. A finite-element-based general purpose code called PZFlex is used to determine the effects of nonlinearity and geometrical complexity of biological structures. It was found that at frequencies of interest in therapeutic applications, the nonlinear effects are usually negligible and the geometrical complexities can be handled through a substructuring procedure. An approximate analytical method with acceptable accuracy is developed as an alternative to the purely numerical approach used in PZFlex. The mechanical and thermal effects in two-layered fluid material systems induced by high-frequency focused ultrasound are calculated through this analytical method. The results are compared with those obtained using PZFlex as a benchmark.

Biomechanical Phenomena↗

PubMed2005

[Magnetic resonance imaging of congenital vaginal anomalies].

OBJECTIVE: To describe the magnetic resonance (MR) imaging manifestations in vaginal anomalies, and to discuss the utility and limit of MR imaging in diagnosis of this abnormality. METHODS: Nine female patients with congenital vaginal anomalies who required surgical intervention were studied. MR imaging and ultrasound of the pelvic was performed before surgery. MR imaging features were retrospectively analyzed correlating with surgery. RESULTS: The vaginal anomalies were categorized into three groups: (1) congenital absence of the vagina and uterus, i.e. Mayer-Rokitansky-Küster-Hauser syndrome (MRKH syndrome) (n=3); (2) vaginal atresia (n=2); and (3) transverse vaginal septum (n=2). There was also one case of absence of vaginal with complicated urinogenital abnormality, and 1 case of obstructed hymen. CONCLUSIONS: MRI is a reliable method for evaluating vaginal anomalies. An accurate MRI examination can be helpful for surgical management.

Abnormalities, Multiple↗

PubMed2004

Persistence of low levels of simian immunodeficiency virus in macaques that were transiently viremic by conventional testing.

Transient SIV viremia after experimental SIV challenge has been documented. Whether SIV persists in these transiently viremic macaques remains unclear. In the present study, we applied a sensitive PCR and found persistent low levels of SIVmne infection (LLSI) (range: 0.1-5.3 SIV DNA copies/10(6) PBMC) in seven macaques that were transiently positive by conventional assays, which was 10(2)- to 10(6)-fold less than those of SIVmne infected monkeys with typical disease progression. SIV envelope V1 sequences remained homogeneous in these macaques for the 6-year study period, with a mean evolution rate of 0.005% per site per year, which was not different from zero (P = 0.612) and significantly lower than that (0.56-1.18%) in macaques with progressive infection of SIVmne. LLSI macaques have remained free from SIV-associated illness, and are still alive 10 years after virus inoculation. Understanding the mechanisms underlying this outcome may provide valuable insight into therapy and vaccine development.

Amino Acid Sequence↗

PubMed2004

Ring finger protein ZIN interacts with human immunodeficiency virus type 1 Vif.

Virion infectivity factor (Vif) protein of human immunodeficiency virus type 1 (HIV-1) is essential for the productive infection of primary human CD4 T lymphocytes and macrophages. Vif overcomes the HIV-inhibitory effects of cellular factor APOBEC3G, which has cytidine deaminase activity. We previously reported the isolation of a Vif-interacting ring finger protein, Triad 3, from a human leukocyte cDNA library, using the yeast two-hybrid system. The full-length cellular protein homologue of Triad 3 has been recently identified as the zinc finger protein inhibiting NF-kappaB (ZIN). Sequence analysis indicates that Triad 3 protein contains all four major ring-like motifs of ZIN. We report here that ZIN binds to purified Vif in vitro and that Triad 3/ZIN interacts with HIV-1 Vif in transfected human 293T cells, as demonstrated by coimmunoprecipitation. To test the biological relevance of this interaction, we produced infectious HIV-1 NL4.3 in the presence or absence of cotransfected ZIN. HIV-1 NL4.3 virus stocks produced in the presence of exogenously expressed ZIN were twofold less infectious in a single-cycle infectivity assay than virus produced in the absence of exogenous ZIN. It was further shown that cells infected with HIV NL4.3 virus stocks produced in the presence of exogenously expressed ZIN were impaired in viral DNA synthesis by twofold. The impairment in viral reverse transcription and the reduction in single-cycle viral infectivity were both shown to be dependent on the presence of Vif in the virus producer cells. The possible mechanisms by which ZIN interferes with the early events of HIV-1 replication are discussed.

Amino Acid Sequence↗

PubMed2004

[Neuropsychiatric symptoms in dementia and elderly people in the community: results from the Beijing Dementia Cooperative Study].

OBJECTIVE: To determine the prevalence of neuropsychiatric symptoms in dementia and normal elderly people living in the Chinese community of Beijing. METHODS: A cross-sectional study derived from the Beijing Dementia Cooperative Study was carried out a population survey was carried out on a total of 1540 participants aged 65 years and older living in Beijing city and rural areas. All the individuals and 373 demented elderly people completed a series of neuropsychological examination and the Neuropsychiatric Inventory (NPI). RESULTS: Among the dementia participants, 49.33% had exhibited neuropsychiatric symptoms (35.66% rated as clinically significant), in which 80.4% reported 2 or more disturbances, with depression (23.86%), apathy (21.72%) and anxiety (20.38%) being most common. Of the 1540 normal individuals, 18.25% of them exhibited neuropsychiatric symptoms (6.49% rated as clinically significant), in which 53% reported 2 or more disturbances, with sleepless (10%), depression (8.9%) and anxiety (6.97%) being the most common. CONCLUSION: To our knowledge, this was the first multi-center study on neuropsychiatric disturbances in dementia and cognitive normal elderly people. Neuropsychiatric symptoms occurred mainly in persons with dementia and of clinical severity. Though the neuropsychiatric disturbances reported in cognitive normal individuals were lower and less serious compared to dementia, they should not be neglected. These finding suggested that a screening programme focusing on identifying these symptoms should be included in the physician's diagnostic tools for dementia.

Aged↗

PubMed2003

Thyroid hormone is not necessary for the development of outer hair cell electromotility.

The outer hair cell (OHC), one of two receptor cell types in the organ of Corti, plays a critical role in mammalian hearing. OHCs enhance basilar membrane motion through a local mechanical feedback process within the cochlea, termed the 'cochlear amplifier'. It is generally believed that the basis of cochlear amplification is a voltage-dependent electromotile response of OHCs. Measurements of electromotility in developing animals indicate that the onset of motility normally occurs around 7 days after birth in altricial rodents such as gerbils and rats. Thyroid hormone (TH) plays a crucial role in the development of the auditory system. Deficiency of the hormone between the late embryonic stage and the second postnatal week can cause severe hearing loss. Several studies suggest that TH deficiency might also affect the development of the cochlear amplifier. The goal of this study was therefore to examine whether TH was necessary for the development of OHC motility. The organ of Corti of gerbils was dissected out at birth and grown in culture with defined concentration of triiodothyronine (T3), the active ligand for the TH receptor. Motility was measured from OHCs isolated from 7-, 11- and 14-day-old cultures. Motility did indeed develop in OHCs deprived of normal concentration of T3. This suggests that the defective auditory function seen in TH-deficient animals is most likely due to morphological and physiological changes in the cochlea, rather than the motor function of the OHCs.

Aging↗

PubMed2003

The role of Vif during HIV-1 infection: interaction with novel host cellular factors.

BACKGROUND: Current research suggests that human immunodeficiency virus type-1 (HIV-1) virion infectivity factor (Vif) acts during viral assembly in producer cells to ensure infectivity in target cells but the exact mechanism of action has not been defined. Vif interacts with Gag, viral protease and RNA and these interactions are proposed to be important for correct particle assembly and stability of the reverse transcription complex. OBJECTIVES: The existence of cells that are either permissive or non-permissive for replication of Vif deficient viruses suggests the involvement of host cellular factors in its function. Current research suggests an association of Vif with the intermediate filament protein, vimentin, and the tyrosine kinase, Hck, but the significance of these associations remains to be defined. More recently HP68, a cellular ATP binding protein, has been shown to be important for capsid formation and an interaction between Vif and HP68 has been shown. Our aim was to further identify host cellular factors involved in Vif function. STUDY DESIGN: We have employed the yeast 2-hybrid system to identify cellular proteins which interact with HIV-1 Vif. Sixteen clones were isolated from a high stringency yeast-2-hybrid screen of a human leucocyte cDNA library with Vif derived from the T-cell tropic HIV-1 strain NL4.3. Of these, 8 clones were confirmed as specifically binding Vif, fully sequenced and identified via GenBank homology searches. RESULTS: Thus far 3 of these clones, spermine/spermidine N1-acetyltransferase, Triad 3 and a novel gene which we have termed 'novel Vif binding protein', have been characterised and represent attractive candidates for mediating Vif action during HIV replication. CONCLUSIONS: Through identification and characterisation of cellular factors interacting with HIV-1 Vif we hope to unravel the mechanism of action of Vif which may ultimately aid therapeutic design.

Gene Products, vif↗