Biomedical subjects

J Fang

Publications and source records attributed to J Fang.

At least 73 records · Page 4Linked to original sources

PubMed2001

TNF receptor-associated factor-2 binding site is involved in TNFR75-dependent enhancement of TNFR55-induced cell death.

TNF recepter-55 is the main mediator of TNF-induced apoptosis. TNF receptor-75-dependent induction or enhancement of cytotoxicity has been explained by intracellular signaling, "ligand passing", or induction of endogenous TNF. To study the function of human TNF receptor-75 (hTR75) and the interaction between human TNF receptor-55 (hTR55) and hTR75 in hTNFalpha-induced cytotoxicity, HEp-2 cells were transfected with bicistronic expression vector of hTR75 and its deletion mutants genes. hTNFalpha-induced cytotoxicity was determined by crystal violet colorimetric method. The expression of hTR75 and its deletion mutants in HEp-2 cells was demonstrated by RT-PCR and indirect ELISA. We found that the overexpressed hTR75 could significantly increase the susceptibility of HEp-2 cells to hTNFalpha which especially required TRAF2 binding site. hTR75 could not only mediate partial hTNFalpha-induced cytotoxicity independently but also fulfill an accessory role in enhancing or synergizing hTR55-mediated cytotoxicity.

Antigens, CD↗

PubMed2001

Isolation and characterization of complex I, rotenone-sensitive NADH: ubiquinone oxidoreductase, from the procyclic forms of Trypanosoma brucei.

Additional characterization of complex I, rotenone-sensitive NADH:ubiquinone oxidoreductase, in the mitochondria of Trypanosoma brucei brucei has been obtained. Both proline:cytochrome c reductase and NADH:ubiquinone oxidoreductase of procyclic T. brucei were inhibited by the specific inhibitors of complex I rotenone, piericidin A, and capsaicin. These inhibitors had no effect on succinate: cytochrome c reductase activity. Antimycin A, a specific inhibitor of the cytochrome bc1 complex (ubiquinol:cytochrome c oxidoreductase), blocked almost completely cytochrome c reductase activity with either proline or succinate as electron donor, but had no inhibitory effect on NADH:ubiquinone oxidoreductase activity. The rotenone-sensitive NADH:ubiquinone oxidoreductase of procyclic T. brucei was partially purified by sucrose density centrifugation of mitochondria solubilized with dodecyl-beta-D-maltoside, with an approximately eightfold increase in specific activity compared to that of the mitochondrial membranes. Four polypeptides of the partially purified enzyme were identified as the homologous subunits of complex I (51 kDa, PSST, TYKY, and ND4) by immunoblotting with antibodies raised against subunits of Paracoccus denitrificans and against synthetic peptides predicted from putative complex I subunit genes encoded by mitochondrial and nuclear T. brucei DNA. Blue Native polyacrylamide gel electrophoresis of T. brucei mitochondrial membrane proteins followed by immunoblotting revealed the presence of a putative complex I with a molecular mass of 600 kDa, which contains a minimum of 11 polypeptides determined by second-dimensional Tricine-SDS/PAGE including the 51 kDa, PSST and TYKY subunits.

Animals↗

PubMed2001

A critical approach to noncardiac chest pain: pathophysiology, diagnosis, and treatment.

Approximately 30% of coronary angiograms performed in this country are negative for significant coronary artery disease. These patients are classified as having noncardiac or unexplained chest pain (UCP). Despite the good overall prognosis, this condition has significant morbidity and costs. The pathophysiology of this condition is likely caused by overlapping cardiac, esophageal, and psychiatric abnormalities with visceral hyperalgesia playing a central role. Gastroenterologists are often consulted in the evaluation of these patients because esophageal disorders are among the most common conditions associated with UCP. However, clinical symptoms are unreliable in differentiating between esophageal and cardiac causes of UCP. Gastroesophageal reflux disease, not esophageal motility disorders, is the most common esophageal disorder present in patients with UCP. The most useful diagnostic test in the evaluation of UCP is 24-h pH monitoring. An initial empiric trial of high-dose acid suppression is the most cost-effective intervention in the management of these patients. A clinical algorithm is suggested for the evaluation and treatment of UCP.

Algorithms↗

PubMed2001

Repeated formaldehyde effects in an animal model for multiple chemical sensitivity.

Chemical intolerance is a phenomenon observed in multiple chemical sensitivity (MCS) syndrome, an ill-defined disorder in humans attributed to exposure to volatile organic compounds. Amplification of symptoms in individuals with MCS resembles the phenomenon of psychostimulant- and stress-induced sensitization in rodents. We have recently tested in rats the hypothesis that repeated chemical exposure produces sensitization of central nervous system (CNS) circuitry. A rat model of MCS in our laboratory has employed several endpoints of CNS function after repeated formaldehyde (Form) exposure (1 h/day x 5 days/week x 4 weeks). Repeated Form exposure produced behavioral sensitization to later cocaine injection, suggesting altered dopaminergic sensitivity in mesolimbic pathways. Rats given repeated Form also demonstrated increased fear conditioning to odor paired with footshock, implicating amplification of neural circuitry guiding fear responding to a conditioned odor cue. Recent studies examining the effects of repeated Form on locomotor activity during each daily exposure showed a decrease in rearing activity after 12-15 days of Form exposure compared to air-exposed controls. EEG recordings taken 1 week after withdrawal from daily Form revealed altered sleep architecture. Some of the differences in sleep disappeared after subsequent brief (15 min) challenge with Form the next day. Overall, the findings indicate that repeated low-level chemical exposure produces behavioral changes that may be akin to those observed in individuals with MCS, such as greater sensitivity to chemicals manifest as increased anxiety upon chemical exposure and altered sleep and/or fatigue. Study of the underlying CNS changes will provide a basis for mechanistically based animal models for MCS.

Animals↗

PubMed2001

The role of cytokines in physiological sleep regulation.

Several growth factors (GFs) are implicated in sleep regulation. It is posited that these GFs are produced in response to neural activity and affect input-output relationships within the neural circuits where they are produced, thereby inducing a local state shift. These GFs also influence synaptic efficacy. All the GFs currently identified as sleep regulatory substances are also implicated in synaptic plasticity. Among these substances, the most extensively studied for their role in sleep regulation are interleukin-1beta (IL-1) and tumor necrosis factor alpha (TNF). Injection of IL-1 or TNF enhances non-rapid eye movement sleep (NREMS). Inhibition of either IL-1 or TNF inhibits spontaneous sleep and the sleep rebound that occurs after sleep deprivation. Stimulation of the endogenous production of IL-1 and TNF enhances NREMS. Brain levels of IL-1 and TNF correlate with sleep propensity; for example, after sleep deprivation, their levels increase. IL-1 and TNF are part of a complex biochemical cascade regulating sleep. Downstream events include nitric oxide, growth hormone releasing hormone, nerve growth factor, nuclear factor kappa B, and possibly adenosine and prostaglandins. Endogenous substances moderating the effects of IL-1 and TNF include anti-inflammatory cytokines such as IL-4, IL-10, and IL-13. Clinical conditions altering IL-1 or TNF activity are associated with changes in sleep, for example, infectious disease and sleep apnea. As our knowledge of the biochemical regulation of sleep progresses, our understanding of sleep function and of many clinical conditions will improve.

Adenosine↗

PubMed2001

Human T-cell leukemia virus type 1 (HTLV-1) infection of mice: proliferation of cell clones with integrated HTLV-1 provirus in lymphoid organs.

Human T-cell leukemia virus type 1 (HTLV-1) is suggested to cause adult T-cell leukemia after 40 to 50 years of latency in a small percentage of carriers. However, little is known about the pathophysiology of the latent period and the reservoir organs where polyclonal proliferation of cells harboring integrated provirus occurs. The availability of animal models would be useful to analyze the latent period of HTLV-1 infection. At 18 months after HTLV-1 infection of C3H/HeJ mice inoculated with the MT-2 cell line, which is an HTLV-1-producing human T-cell line, HTLV-1 provirus was detected in spleen DNA from eight of nine mice. No more than around 100 proviruses were found per 10(5) spleen cells. Cellular sequences flanking the 3' long terminal repeat (LTR) and the clonalities of the cells which harbor integrated HTLV-1 provirus were analyzed by linker-mediated PCR. The results showed that the flanking sequences are of mouse genome origin and that polyclonal proliferation of the spleen cells harboring integrated HTLV-1 provirus had occurred in three mice. A sequence flanking the 5' LTR was isolated from one of the mice and revealed the presence of a 6-nucleotide duplication of cellular sequences, consistent with typical retroviral integration. Moreover, PCR was performed on DNA from infected tissues, with LTR primers and primers derived from seven novel flanking sequences of the three mice. Data revealed that the expected PCR products were found from lymphatic tissues of the same mouse, suggesting that the lymphatic tissues were the reservoir organs for the infected and proliferating cell clones. The mouse model described here should be useful for analysis of the carrier state of HTLV-1 infection in humans.

Animals↗

PubMed2001

Glial cell line-derived neurotrophic factor promotes sleep in rats and rabbits.

Various growth factors (e.g., growth hormone-releasing hormone, acidic fibroblast growth factor, nerve growth factor, brain-derived neurotrophic factor, and interleukin-1) are implicated in sleep regulation. It is hypothesized that neuronal activity enhances the production of such growth factors, and they in turn form part of the sleep regulatory mechanism. Glial cell line-derived neurotrophic factor (GDNF) promotes development, differentiation, maintenance, and regeneration of neurons, and its production is induced by well-characterized sleep regulatory substances such as interleukin-1 and tumor necrosis factor. Therefore, we investigated whether GDNF would promote sleep. Twenty-six male Sprague-Dawley rats and 30 male New Zealand White rabbits were surgically implanted with electroencephalogram (EEG) and electromyogram (EMG; rats only) electrodes, a brain thermistor, and a lateral intracerebroventricular cannula. The animals were injected intracerebroventricularly with pyrogen-free saline and on a separate day with one of the following doses of GDNF: 5, 50, and 500 ng in rabbits and 50 and 500 ng in rats. The EEG, brain temperature, EMG (in rats), and motor activity (in rabbits) were recorded for 23 h after the intracerebroventricular injection. GDNF (500-ng dose) increased the time spent in nonrapid eye movement sleep in both rats and rabbits. Rapid eye movement sleep was not affected by the lower doses of GDNF but was inhibited in rabbits after the high dose. EEG slow-wave activity was not affected by GDNF. The current results provide further evidence that various growth factors are involved in sleep regulation.

Animals↗

PubMed2001

Vagotomy attenuates tumor necrosis factor-alpha-induced sleep and EEG delta-activity in rats.

Much evidence suggests that tumor necrosis factor-alpha (TNF-alpha) is involved in the regulation of physiological sleep. However, it remains unclear whether peripheral administration of TNF-alpha induces sleep in rats. Furthermore, the role of the vagus nerve in the somnogenic actions of TNF-alpha had not heretofore been studied. Four doses of TNF-alpha were administered intraperitoneally just before the onset of the dark period. The three higher doses of TNF-alpha (50, 100, and 200 microg/kg) dose dependently increased nonrapid eye movement sleep (NREMS), accompanied by increases in electroencephalogram (EEG) slow-wave activity. TNF-alpha increased EEG delta-power and decreased EEG alpha- and beta-power during the initial 3 h after injection. In vagotomized rats, the NREMS responses to 50 or 100 microg/kg of TNF-alpha were attenuated, while significant TNF-alpha-induced increases in NREMS were observed in a sham-operated group. Moreover, the vagotomized rats failed to exhibit the increase in EEG delta-power induced by TNF-alpha intraperitoneally. These results suggest that peripheral TNF-alpha can induce NREMS and vagal afferents play an important role in the effects of peripheral TNF-alpha and EEG synchronization on sleep. Intraperitoneal TNF-alpha failed to affect brain temperature at the doses tested, thereby demonstrating that TNF-alpha-induced sleep effects are, in part, independent from its effects on brain temperature. Results are consistent with the hypothesis that a cytokine network is involved in sleep regulation.

Animals↗

PubMed2001

Interleukin-15 and interleukin-2 enhance non-REM sleep in rabbits.

Interleukin (IL)-15 and -2 share receptor- and signal-transduction pathway (Jak-STAT pathway) components. IL-2 is somnogenic in rats but has not been tested in other species. Furthermore, the effects of IL-15 on sleep have not heretofore been described. We investigated the somnogenic actions of IL-15 in rabbits and compared them with those of IL-2. Three doses of IL-15 or -2 (10, 100, and 500 ng) were injected intracerebroventriculary at the onset of the dark period. In addition, 500 ng of IL-15 and -2 were injected 3 h after the beginning of the light period. IL-15 dose dependently increased non-rapid eye movement sleep (NREMS) and induced fever. IL-15 inhibited rapid eye movement sleep (REMS) after its administration during the light period; however, all doses of IL-15 failed to affect REMS if given at dark onset. IL-2 also dose dependently increased NREMS and fever. IL-2 inhibited REMS, and this effect was observed only in the light period. IL-15 and -2 enhanced electroencephalographic (EEG) slow waves during the initial 9-h postinjection period, then, during hours 10-23 postinjection, reduced EEG slow-wave activity. Current data support the notion that the brain cytokine network is involved in the regulation of sleep.

Animals↗

PubMed2001

Interleukin-18 promotes sleep in rabbits and rats.

Interleukin (IL)-1beta is involved in physiological sleep regulation. IL-18 is a member of the IL-1 family, and its signal-transduction mechanism is similar to that of IL-1. Therefore, we hypothesized that IL-18 might also be involved in sleep regulation. Three doses of IL-18 (10, 100, and 500 ng) were injected intracerebroventricularly (icv) into rabbits at the onset of the dark period. The two higher doses of IL-18 markedly increased non-rapid eye movement sleep (NREMS), accompanied by increases in brain temperature (Tbr). These effects were lost after the heat inactivation of IL-18. The 500 ng of IL-18 injection during the light period also increased NREMS and Tbr. Similar results were obtained after icv injection of 100 ng of IL-18 into rats. Furthermore, intraperitoneal injection of 30 microg/kg of IL-18 slightly, but significantly, increased NREMS, whereas it significantly decreased electroencephalogram slow-wave activity in rats. Intraperitoneal IL-18 failed to induce fever. An anti-human IL-18 antibody had little effect on spontaneous sleep in rabbits, although the anti-IL-18 antibody significantly attenuated muramyl dipeptide-induced sleep. These data suggest that IL-18 is involved in mechanisms of sleep responses to infection.

Acetylmuramyl-Alanyl-Isoglutamine↗

PubMed2001

Conditions that affect sleep alter the expression of molecules associated with synaptic plasticity.

Many theories propose that sleep serves a purpose in synaptic plasticity. We tested the hypothesis, therefore, that manipulation of sleep would affect the expression of molecules known to be involved in synaptic plasticity. mRNA expression of four molecules [brain-derived neurotrophic factor (BDNF), activity-regulated cytoskeleton-associated protein (Arc), matrix metalloproteinase-9 (MMP-9), and tissue plasminogen activator (tPA)] was determined after 8 h of sleep deprivation and after 6 h of a mild increase in ambient temperature, a condition that enhances sleep in rats. After sleep deprivation, BDNF, Arc, and tPA mRNAs in the cerebral cortex increased while MMP-9 mRNA levels decreased. Conversely, after enhanced ambient temperature, BDNF, Arc, and tPA mRNAs decreased while MMP-9 mRNA increased. In the hippocampus, sleep deprivation did not significantly affect BDNF and tPA expression, although Arc mRNA increased and MMP-9 mRNA decreased. Brain temperature enhancement decreased Arc mRNA levels in the hippocampus but did not affect BDNF, MMP-9, or tPA in this area. Results are consistent with the notion that sleep plays a role in synaptic plasticity.

Animals↗

PubMed2001

Trend of stroke hospitalization, United States, 1988-1997.

BACKGROUND AND PURPOSE: Age-adjusted stroke mortality in the United States has declined in recent decades. However, the course of stroke incidence is less certain. To address this issue, we determined trends of stroke hospitalization and in-hospital case fatality during 1988-1997. METHODS: Stroke hospitalization was estimated from National Hospital Discharge Survey as numerator and Current Population Survey as denominator. Hospitalization rates were determined and stratified by patient characteristics. Average length of hospital stay was also determined. In-hospital mortality was specified by sex, age, and other patient characteristics. The change in these rates over 10 years and average annual percent changes were calculated. RESULTS: During 1988-1997, age-adjusted stroke hospitalization rate increased 18.6% (from 560 to 664/100 000; P=0.043), while total hospitalization increased from 592 811 to 821 760. This increase was limited to persons aged >/=65 years. Patients in the South had the highest stroke hospitalization rates, and those in the West had the lowest. Overall, 58% of strokes were classified as ischemic, 13% as hemorrhagic, and 29% as other. Over these 10 years, stroke patients having coincident diabetes, hypertension, and congestive heart failure increased 17.4% (P=0.17), 34% (P=0.05), and 31% (P=0.091), respectively. The average length of hospital stay fell from 11.1 to 6.2 days (44.1%; P=0.012). As a result, despite an increase in hospitalizations for stroke, the total person-days in hospital actually decreased by 22% (P=0.06). CONCLUSIONS: The declining age-adjusted stroke mortality in the United States has not been accompanied by a fall in hospitalization over recent years. Thus far, however, decrease in length of stay has more than offset increased admission. At the same time, the sharp drop in hospital case fatality rates suggests that continuing decline in stroke mortality may be due, in large part, to improved survival after acute stroke.

Acute Disease↗

PubMed2001

Hyperinsulinism/hyperammonemia syndrome in children with regulatory mutations in the inhibitory guanosine triphosphate-binding domain of glutamate dehydrogenase.

The hyperinsulinism/hyperammonemia (HI/HA) syndrome is a form of congenital hyperinsulinism in which affected children have recurrent symptomatic hypoglycemia together with asymptomatic, persistent elevations of plasma ammonium levels. We have shown that the disorder is caused by dominant mutations of the mitochondrial enzyme, glutamate dehydrogenase (GDH), that impair sensitivity to the allosteric inhibitor, GTP. In 65 HI/HA probands screened for GDH mutations, we identified 19 (29%) who had mutations in a new domain, encoded by exons 6 and 7. Six new mutations were found: Ser(217)Cys, Arg(221)Cys, Arg(265)Thr, Tyr(266)Cys, Arg(269)Cys, and Arg(269)HIS: In all five mutations tested, lymphoblast GDH showed reduced sensitivity to allosteric inhibition by GTP (IC(50), 60--250 vs. 20--50 nmol/L in normal subjects), consistent with a gain of enzyme function. Studies of ATP allosteric effects on GDH showed a triphasic response with a decrease in high affinity inhibition of enzyme activity in HI/HA lymphoblasts. All of the residues altered by exons 6 and 7 HI/HA mutations lie in the GTP-binding domain of the enzyme. These data confirm the importance of allosteric regulation of GDH as a control site for amino acid-stimulated insulin secretion and indicate that the GTP-binding site is essential for regulation of GDH activity by both GTP and ATP.

Enzyme Inhibitors↗

PubMed2001

Structural characterization and immunomodulating activity of a complex glucan from spores of Ganoderma lucidum.

A polysaccharide with a molecular weight of 1.26 x 10(5), obtained from the sporoderm-broken spores of Ganoderma lucidum, was purified by anion-exchange and gel-permeation chromatography. This polysaccharide had a strong effect on suppressing the antibody production and the Con A or LPS induced lymphocyte proliferation in mice. Chemically, the structure of the polysaccharide was identified by methylation analysis, 1 D, 2 D NMR and ESI-MS spectroscopic studies of the native one and of the oligosaccharide fragments generated by partial acid hydrolysis, Smith degradation, and acetolysis. It was concluded that the intact polysaccharide was a complex beta-D-glucan consisting of a (1-->6)-linked backbone chain, in which every other glucosyl residue was substituted at C-3 or C-4 with mono-, di- and trisaccharide branches.

Adjuvants, Immunologic↗

PubMed2001

Angiogenesis inhibitor TNP-470 during bone marrow transplant: safety in a preclinical model.

High-dose therapy with stem cell rescue is a treatment option for patients with advanced solid tumors. Although this approach has promise for some pediatric cancers, especially neuroblastoma, it is limited by the risk of relapse posttransplant as well as concern about possible reinfused tumor cells in autologous stem cell products. Antiangiogenic agents given during and after recovery from high-dose therapy with stem cell rescue may decrease the risk of relapse. TNP-470 is an antiangiogenic agent now in clinical trials. Although it inhibits the growth of bone marrow (BM) colony-forming cells in vitro, no significant hematological toxicity has been seen in Phase I trials. To assess the feasibility of using antiangiogenic agents during the period of posttransplant hematopoietic engraftment, we have developed a model of stem cell transplant in mice. Mice were lethally irradiated and then rescued with stem cells containing a transgene expressed in the hematopoietic lineage. Mice were then treated with TNP-470 or placebo, and assessed for survival, successful engraftment, and kinetics of engraftment. Both treated and control mice demonstrated reliable multilineage engraftment as well as normal lymphoid maturation with no excess mortality in the treated group. WBCs were lower but still within the normal range at d+28 in mice treated with bolus TNP-470, but not in those treated with continuous infusion TNP-470, compared with controls. These data indicate that inhibitors of angiogenesis do not adversely impact engraftment after stem cell transplantation.

Angiogenesis Inhibitors↗

PubMed2001

[Amplification and analysis of T-DNA flanking sequences in transgenic rice].

Rice transformation mediated by Agrobacterium tumefaciens has technically matured to some extent, but the mechanics of T-DNA integration in transgenic rice remains largely unknown. Using thermal asymmetric interlaced PCR (TAIL-PCR), we analyzed the flanking sequences of T-DNAs in transgenic rice plants, in which the resistance gene for rice bacterial blight disease, Xa21, had been integrated stably. Sequence analysis of 24 fragments amplified by TAIL-PCR showed that of them 14 were rice genomic DNA, 9 contained vector backbone sequences, and one was a fragment of the exogenous gene Xa21. The characteristics of the 14 rice genomic DNA sequences at T-DNA integrated sites are significantly different from those of the reported rice genomic sequences into which exogenous genes were integrated through direct DNA transformation methods. T-DNA border sequences integrated in rice genome have similar features as those integrated in dicotyledonous genomes. In the backbone containing flanking sequences (37.5%, 9/24) vector backbones appeared in different types.

Base Sequence↗

PubMed2001

[Combustion characteristics of municipal solid waste in fluidized bed].

For the experimental investigation on the combustion characteristics of Municipal Solid Waste(MSW) in Fluidized Bed, a lab scale Fluidized Bed facility was constructed. Single and mixed municipal solid waste burning in Fluidized Bed showed that dry waste can be burnt quickly at the bed temperature of 500 degrees C, and furnace temperature increased about 30-50 degrees C. Many kinds of combustion runs were conducted in this Fluidized Bed combustion facility. The parameters examined were air flow rate(from 5.5 m3/h to 7.5 m3/h), form of fuels(scrap or whole), moisture content and so on. Concentration of CO2, CO, SO2 and NOx in the flue gas were monitored and recorded every 5 seconds. The temperatures along the reactor were recorded every 10 seconds.

Hot Temperature↗

PubMed2001

Pregabalin enhances nonrapid eye movement sleep.

Pregabalin, an analog of gamma-aminobutyric acid (GABA) that does not interact with GABA receptors, is in development as an analgesic, an anticonvulsant, and an anxiolytic. We evaluated the potential somnogenic actions of pregabalin in rats and compared it to those of triazolam, a widely used hypnotic. Pregabalin increased the duration of nonrapid eye movement sleep (NREMS) and decreased rapid eye movement sleep (REMS) after either dark onset or light onset administration. Triazolam increased duration of NREMS and had no effect on duration of REMS. Pregabalin markedly increased the duration of NREMS episodes and decreased the number of NREMS episodes. Power spectrum analysis revealed pregabalin-induced dose-dependent increases in relative delta power after administration. In contrast, triazolam decreased electroencephalographic power density in low frequency bands. Results suggest that pregabalin is a potential sleep modulating agent.

Animals↗