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F Shen

Publications and source records attributed to F Shen.

At least 19 recordsLinked to original sources
PubMed2006

Nullifying drug-induced sensitization: behavioral and electrophysiological evaluations of dopaminergic and serotonergic ligands in methamphetamine-sensitized rats.

Repeated exposure to methamphetamine produces a persistent enhancement of the acute motor effects of the drug, commonly referred to as behavioral sensitization. Behavioral sensitization involves monoaminergic projections to several forebrain nuclei. We recently revealed that the ventral pallidum (VP) may also be involved. In this study, we sought to establish if treatments with antagonists or partial agonists to monoaminergic receptors could "reverse" methamphetamine-induced behavioral and VP neuronal sensitization. Behavioral sensitization was obtained in rats with five once-daily s.c. injections of 2.5mg/kg methamphetamine, an effect that persisted for at least 60 days. After the development of sensitization, 15 once-daily treatments of mirtazapine (a 5-HT(2/3), alpha(2) and H(1) antagonist), SKF38393 (D(1) partial agonist) or SCH23390 (dopamine D(1) antagonist) nullified indices of motor sensitization as assessed by measuring the motoric response to an acute methamphetamine challenge 30 days after the fifth repeated methamphetamine treatment. VP neurons recorded in vivo from methamphetamine-sensitized rats at the 30-day withdrawal time also showed a robust downward shift in the excitatory responses observed to an acute i.v. methamphetamine challenge in non-sensitized rats. This decreased excitatory effect was reversed by mirtazapine, but not by other antagonists that were tested. These data suggest a potential therapeutic benefit for mirtazapine in the treatment of methamphetamine addiction, and point to a possible role for the VP in the sensitization process to methamphetamine.

Action Potentials↗
PubMed2006

Modified Bilston nonlinear viscoelastic model for finite element head injury studies.

This paper proposes a modified nonlinear viscoelastic Bilston model (Bilston et al., 2001, Biorheol., 38, pp. 335-345). for the modeling of brain tissue constitutive properties. The modified model can be readily implemented in a commercial explicit finite element (FE) code, PamCrash. Critical parameters of the model have been determined through a series of rheological tests on porcine brain tissue samples and the time-temperature superposition (TTS) principle has been used to extend the frequency to a high region. Simulations by using PamCrash are compared with the test results. Through the use of the TTS principle, the mechanical and rheological behavior at high frequencies up to 10(4) rads may be obtained. This is important because the properties of the brain tissue at high frequencies and impact rates are especially relevant to studies of traumatic head injury. The averaged dynamic modulus ranges from 130 Pa to 1500 Pa and loss modulus ranges from 35 Pa to 800 Pa in the frequency regime studied (0.01 rads to 3700 rads). The errors between theoretical predictions and averaged relaxation test results are within 20% for strains up to 20%. The FEM simulation results are in good agreement with experimental results. The proposed model will be especially useful for application to FE analysis of the head under impact loads. More realistic analysis of head injury can be carried out by incorporating the nonlinear viscoelastic constitutive law for brain tissue into a commercial FE code.

Animals↗
PubMed2005

An adaptive incremental LBG for vector quantization.

This study presents a new vector quantization method that generates codewords incrementally. New codewords are inserted in regions of the input vector space where the distortion error is highest until the desired number of codewords (or a distortion error threshold) is achieved. Adoption of the adaptive distance function greatly increases the proposed method's performance. During the incremental process, a removal-insertion technique is used to fine-tune the codebook to make the proposed method independent of initial conditions. The proposed method works better than some recently published efficient algorithms such as Enhanced LBG (Patane, & Russo, 2001) for traditional tasks: with fixed number of codewords, to find a suitable codebook to minimize distortion error. The proposed method can also be used for new tasks that are insoluble using traditional methods: with fixed distortion error, to minimize the number of codewords and find a suitable codebook. Experiments for some image compression problems indicate that the proposed method works well.

Algorithms↗
PubMed2001

Electroretinographic abnormalities in a rat glaucoma model with chronic elevated intraocular pressure.

The purpose of this study was to determine the ability of electroretinographic (ERG) measurements to document progression of the retinopathy in a rat glaucoma model. Thirty four rats with a chronic intraocular pressure (IOP) elevation induced in one eye by cautery of three episcleral/extra-orbital veins were studied in four separate groups. ERGs were recorded sequentially in Group A rats (n = 12) at baseline, and after approximately 20, 40 and 60 days of high IOP, and in three additional groups of rats (n = 6 or 10 per group) after approximately 58, 30 and 175 days of high IOP, respectively. Scotopic ERG parameters recorded simultaneously from both eyes in Group A rats were: a- and b-wave amplitudes, implicit times, oscillatory potential amplitudes (OPs) determined at three different light-flash intensities, and the light-adapted (photopic) ERG b-wave amplitude. In the other groups of rats, only scotopic ERG a-wave, b-wave and OP amplitudes were measured.In Group A rats that were followed sequentially, all the ERG parameters recorded with attenuated stimuli showed significant time-dependent changes in glaucomatous eyes relative to their contralateral normal eyes, with OPs showing the earliest significant difference after only 3 weeks of high IOP. When different groups of unilateral glaucomatous rats were compared beyond 8 weeks of elevated IOP only the OPs showed a continued decrease with time and good discrimination between glaucoma and normal eyes. Over a 25 week period of high IOP the scotopic OPs measured with attenuated light stimuli declined at the rate of approximately 1.5% per week and provided the best ERG measure to monitor progression of retinal pathophysiology in the vein-occlusion rat glaucoma model.

Adaptation, Ocular↗
PubMed2001

Effect of pilocarpine 4% in combination with latanoprost 0.005% or 8-iso prostaglandin E2 0.1% on intraocular pressure in laser-induced glaucomatous monkey eyes.

PURPOSE: To compare the effect of pilocarpine, an agent that reduces uveoscleral outflow, on the ocular hypotensive efficacy of latanoprost and 8-iso prostaglandin E2 (PGE2). METHODS: Each of the two treatment groups was composed of the same eight monkeys with unilateral laser-induced glaucoma. Intraocular pressure (IOP) was measured hourly for 6 hours beginning at 9:00 AM on the baseline day (Thursday before treatment week) and on treatment days 1, 3, and 5 (Monday, Wednesday, and Friday). On all five treatment days, one drop of pilocarpine 4% was administered at 9:00 AM and 3:00 PM and one drop of latanoprost 0.005% or 25 microL of 8-iso PGE2 0.1% was administered at 10:00 AM and 4:00 PM. RESULTS: One hour after pilocarpine instillation on day 1, the reduction of IOP was similar (P > 0.90) in both treatment groups, 7.6 +/- 1.1 mm Hg (mean +/- standard error of the mean ) in the latanoprost group and 7.4 +/- 0.8 mm Hg in the 8-iso PGE2 group. However, the IOP effects of the two treatment groups became significantly different (P < 0.05) beginning 2 hours after dosing with latanoprost or 8-iso PGE, on day 1. A difference (P < 0.05) between the two groups persisted at all subsequent measurements. The reduction of IOP lessened with repeated dosing in the latanoprost and 8-iso PGE2 groups. Three hours after dosing with pilocarpine and two hours after dosing with the prostanoids, the IOP reduction was 8.3 +/- 0.9 mm Hg in the latanoprost group and 9.9 +/- 0.6 mm Hg in the 8-iso PGE2 group on day 1, and 2.1 +/- 1.0 mm Hg in the latanoprost group and 7.3 +/- 0.9 mm Hg in the 8-iso PGE1 group on day 5. CONCLUSIONS: The smaller reductions in IOP with pilocarpine and latanoprost than with pilocarpine and 8-iso PGE2 show that pilocarpine blocks much more of the ocular hypotensive effect of latanoprost than of 8-iso PGE2. The results also indicate that pilocarpine and latanoprost are mutually antagonistic. Enhancement of uveoscleral outflow appears to account for most of the ocular hypotensive effect of latanoprost and for much less of the ocular hypotensive effect of 8-iso prostaglandin E2.

Administration, Topical↗
PubMed2001

[Relationship of vitamin D receptor polymorphism with breast cancer].

OBJECTIVE: To detect the association between vitamin D receptor polymorphism and breast cancer. METHODS: Polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP) method was used. Two restriction fragment length polymorphisms in the 3'region of vitamin D receptor (VDR) gene, Taq I and Apa I, were tested for association with breast cancer risk in 86 females with breast cancer and 134 healthy female controls. RESULTS: Allele frequencies of the 3'Taq I polymorphism showed a significant association (P=0.0004, OR:5.39,CI:1.81-17.20). The further study of genotype found the association of Tt, tt with breast cancer. The haplotype analysis of Apa I and Taq I showed a linkage disequilibrium between t-allele and A-allele. The frequency of tA haplotype was higher in breast cancer patients than in controls (P=0.001), indicating that tA haplotype is associated with breast cancer. The alleles and haplotype of the two loci had not any difference among the clinical subgroups. CONCLUSION: There is association between vitamin D receptor polymorphism and breast cancer.

Adult↗
PubMed2001

[Complex segregation analysis of systemic lupus erythematosus].

OBJECTIVE: To explore the genetic model of systemic lupus erythematosus(SLE). METHODS: Complex segregation analysis was performed by using statistical analysis for genetic epidemiology-REGTL(SAGE-REGTL). The genetic model and gene frequency were estimated. 300 pedigrees with SLE were collected from 300 patients as probands. RESULTS: The complex segregation analysis found the genetic model of SLE to be additive,the gene frequency 0.336. The authors believe the possibility of some different modes coexisting under different circumstances. The genetic effect on young man is stronger than that on old one. CONCLUSION: This study suggests that the genetic mode of SLE could be the major gene trait, and additive mode is the best fitted one.

Adolescent↗
PubMed2001

[Effects of angiotensin II on the 3H-TdR incorporation and synthesis of collagen in cultured bovine trabecular meshwork cells].

OBJECTIVE: To investigate the effects of angiotensin II (Ang II) on the cell proliferation and collagen synthesis of bovine trabecular meshwork (TM) cells in vitro. It may probe into the mechanism of primary open-angle glaucoma(POAG). METHODS: (1) The bovine trabecular meshwork cells were cultured and identified by immunohistochemistry method(neuronal specific enolas, NSE, factor related antigan). The growing characteristics and morphological feature of cultured primary and passaged cells were observed by invered microscope and eletron-microscope; (2) Ang II(1 x 10(-7) mol.L-1 and 1 x 10(-8) mol.L-1) and angiotensin receptor type I (AT1) antagonist (losartan) were incubated with cultured TM cells. The cellular proliferation was measured by 3H-thymidine(3H-TdR) incorporation assay and collagen synthesis was indirectly professed though detects the hydroxyproline of medium with chemistry methods. RESULTS: The cells of bovine trabecular meshwork were cultured successfully. Most of them were epithelia type. Ang II increased the TM cells uptake of 3H-TdR and inhibited by losartan partially. Meanwhile the hydroxyproline of medium was increased correspondingly. CONCLUSION: Establishing the method of culturing bovine trabecular meshwork cells is an important method for researching the characteristics of TM cells. Ang II can induce the cell proliferation of bovine TM cells and increase the synthesis of collagen in vitro. The AT1 antagonist may inhibit this cell proliferation effect.

Angiotensin II↗
PubMed2000

"The scarlet E": the presentation of epilepsy in the English language print media.

OBJECTIVE: To examine the coverage of epilepsy in English language newspapers and magazines to determine how they portray the medical risks associated with epilepsy, whether they report research and treatment advances accurately, whether stigmatizing biases toward persons with epilepsy persist, and to examine the sources of errors in reporting about epilepsy. BACKGROUND: The print media reflect and shape current views about epilepsy and other neurologic conditions. They also have the potential to further misconceptions about neurologic issues and particular brain disorders. Persistent myths about epilepsy, such as the ancient belief that it is a demonic disorder, can result in discrimination, emotional difficulties, and reluctance to seek effective treatment. METHODS: A large commercial database was used to search for stories about epilepsy from approximately 2,000 English language newspapers and popular magazines. Two epileptologists independently classified story themes and main sources, and screened for the presence of gross errors in 210 stories about epilepsy or seizures. The authors analyzed the metaphors and terminology used to describe seizures and epilepsy. RESULTS: The majority of English language print stories about epilepsy were accurate depictions of social and medical issues regarding the disorder, most commonly depictions of persons overcoming epilepsy and announcements of new therapies and reports of scientific advances. Thirty-one percent of the stories, however, contained gross errors, most commonly scientific inaccuracy, exaggerated treatment claims, and overestimates of the risks of dying during a seizure. New drug therapies were often described inaccurately by physicians and pharmaceutical spokespersons as curative and without side effects. Patients and their families frequently overemphasized the risk of dying during a seizure and misstated medical issues. Most celebrities with recurring seizures denied having epilepsy. Seizures were described with demonic imagery in 6% of stories. United States epilepsy associations discourage labeling patients as "epileptics"; however, the term was used in 45% of stories. CONCLUSION: Physicians and reporters should be aware of both professional and popular biases that influence the print media's presentation of the causes and consequences of epilepsy.

Anticonvulsants↗
PubMed2000

Eden et al. reply:

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Journal Article↗
PubMed2000

Inhibition of Fas-mediated apoptosis by the B cell antigen receptor through c-FLIP.

Cross-linking of the B cell antigen receptor (BCR) induces resistance to Fas (APO-1 / CD95)-dependent apoptosis and thereby regulates one mechanism of B cell selection during antigen stimulation. To investigate the molecular mechanism by which BCR signaling regulates the Fas pathway, we examined the expression of constituents of the death-inducing signaling complex (DISC), including Fas, FADD, caspase-8 and cellular FLICE-inhibitory protein (c-FLIP). No significant changes in the cellular levels of Fas, FADD or caspase-8 were observed after BCR cross-linking. By contrast, the long isoform of c-FLIP (c-FLIP(L)) was significantly up-regulated by BCR cross-linking in primary B cells and in two B cell lines, A20 and WEHI-279. Moreover, transfection of c-FLIP(L) into A20 cells inhibited Fas-dependent apoptosis and suppressed recruitment of caspase-8 to the DISC. BCR cross-linking or FLIP overexpression also protects B cells from TRAIL-induced apoptosis. Thus, BCR signaling up-regulates c-FLIP(L) and suppresses the Fas- and TRAIL-receptor apoptosis pathways which could be important for tolerance and selection of antigen-specific B cells.

Animals↗
PubMed2000

Enhancement of immunogenicity of tumor cells by cotransfection with genes encoding antisense insulin-like growth factor-1 and B7.1 molecules.

Insulin-like growth factor-1 (IGF-1) is expressed in many tumor cell lines and has a role in both normal cell proliferation and in the growth of cancers. Tumor cells transfected with a vector encoding an IGF-1 antisense cDNA transcriptional cassette driven by the mouse metallothionein-1 promoter become immunogenic and lose their tumorigenicity in syngeneic animals. The enhanced immunogenicity is associated with an up-regulation in the expression of major histocompatibility complex class I molecule on cell surfaces. Blockade of the expression of IGF-1 in tumor cells by the IGF-1 antisense RNA approach is not uniformly effective in the induction of antitumoral protective immunity in low and nonimmunogenic tumor model systems. Here, we report that the immunogenicity of hepa 1-6 hepatoma and SMCC-1 colon carcinoma cells, which are poorly immunogenic and unresponsive to antisense IGF-1 gene transfer, can be induced by cotransfection with genes encoding antisense IGF-1 and mouse B7.1 molecules. The tumor cells modified in this manner become strongly immunogenic and can be used as a cellular vaccine to induce a protective immune response in vivo. Immunization with the transfected tumor cells also results in regression of the established hepa 1-6 hepatoma and SMCC-1 colon cancer. The immunity is tumor-specific and is mediated by CD3+ CD8+ T cells. Cytotoxic T lymphocytes generated in vitro by priming naive spleen cells and in vivo by immunizing mice with the double-transfected tumor cells specifically lysed autologous tumors cells and were effective in adoptive immunotherapy. The data suggest that modification of tumor cells in vitro by cotransfection with genes encoding antisense IGF-1 and B7.1 molecules may open a new avenue for cancer immunogene therapy.

Adjuvants, Immunologic↗
PubMed2000

Genetic epidemiology study of pathological myopia.

OBJECTIVE: To explore the genetic epidemiology of pathological myopia (PM), including hereditary and genetic model. METHODS: The simple segregation analysis was done by SEGRANB. The values of segregation ratio p and the proportion of sporadic cases x were estimated. The complex segregation analysis was performed using SAGE-REGD. The genetic model and gene frequency were estimated. The 62 pedigrees with PM were random samples from hospital patients. RESULTS: By simple segregation analysis, the genetic pattern of N*N is autosomal recessive and the frequency of sporadic cases is approximately 65.72%. The genetic pattern of A*N may be autosomal recessive (but autosomal dominant cannot be excluded), the frequency of sporadic cases is approximately 35.14%. By complex segregation analysis, the genetic model of PM is autosomal recessive and the gene frequency is 0.147385. CONCLUSION: PM is compatible with autosomal recessive inheritance (autosomal dominant not excluded ), the sporadic cases are existent and the gene frequency is 0.147385.

Female↗
PubMed2000

Glaucoma in primates: cytochrome oxidase reactivity in parvo- and magnocellular pathways.

PURPOSE: To evaluate the differential effects of ganglion cell depletion from experimental glaucoma on the relative metabolic activities of neurons in the parvo (P)- and magno (M)-cellular visual pathways of the macaque visual system. METHODS: Monocular experimental glaucoma was induced in monkeys (Macaca mulatta and M. fascicularis) by applying a laser to the trabecular meshwork to increase intraocular pressure (IOP). After other behavioral and electrophysiological studies, the lateral geniculate nuclei (LGNs) and the primary visual cortices were analyzed for functional afference from surviving ganglion cells, indicated by cytochrome oxidase (CO) histochemistry. RESULTS: CO reactivity (COR) indicated a general reduction in neural metabolism with increasing severity of glaucoma. COR in the LGNs was reduced to the same degree in both the P- and M-cellular layers. In layer 4Cbeta of the V1 cortex, the reactivity was always reduced more than in the layer 4Calpha division. CONCLUSIONS: Experimental glaucoma in monkeys reduces visual afference to the central nervous system, thereby reducing the metabolic drive as indicated by COR. The detrimental effect of glaucoma did not appear to be any greater for the M-cell, rather than the P-cell pathway in the LGN or in the visual cortex. Both are affected by the duration and severity of the experimental glaucoma. Overall, the alterations in metabolism of neurons in the parallel visual pathways supplied by the Palpha and Pbeta ganglion cells do not suggest that tests based on the functional properties of one or the other would provide optimal assessment of glaucoma.

Animals↗
PubMed2000

Use of carnosine as a natural anti-senescence drug for human beings.

Carnosine is an endogenous free-radical scavenger. The latest research has indicated that apart from the function of protecting cells from oxidation-induced stress damage, carnosine appears to be able to extend the lifespan of cultured cells, rejuvenate senescent cells, inhibit the toxic effects of amyloid peptide (A beta), malondialdehyde, and hypochlorite to cells, inhibit glycosylation of proteins and protein-DNA and protein-protein cross-linking, and maintain cellular homeostasis. Also, carnosine seems to delay the impairment of eyesight with aging, effectively preventing and treating senile cataract and other age-related diseases. Therefore, carnosine may be applied to human being as a drug against aging.

Aging↗
PubMed2000

[The association and linkage analysis between the FcgammaR II a-131 and system lupus erythematosus].

OBJECTIVE: To shed light on the relationship between FcgammaR II a-131 and systemic lupus erythematosus(SLE) in southern Chinese Han population. METHODS: A population-based and family-based study was carried out. FcgammaR II a-131 of each subject was measured by using PCR-allele specific oligonucleotide hybridization(ASO) method. RESULTS: (1) The distribution of FcgammaR II A-131 genotype in cases is significantly different from that in controls (P<0.05). So is the frequency of FcgammaR II aR-131 allele (P < 0.01) which suggests that subjects who have R131 allele tend to be more susceptible to SLE. The subjects with R/R131 homozygous genotype have a higher risk of suffering from SLE. (2) The distribution of FcgammaR II a-131 varies in different races, with identical distribution type among Chinese and Japanese. (3) The results of family-based association analysis and transmitted/disequilibrium test(TDT) suggest that there is not any linkage evidence between FcgammaR II a-131 and SLE. Possibly, the sample size was too small to get positive result. CONCLUSION: This study suggests that FcgammaR II a-131 is a major factor predisposing to the development of SLE in southern Chinese Han population.

Alleles↗