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Biomedical subjects

Zhong Chen

Publications and source records attributed to Zhong Chen.

At least 91 records · Page 5Linked to original sources
PubMed2005

Influence of low dietary histamine on seizure development of chemical kindling induced by pentylenetetrazol in rats.

AIM: To determine the role of dietary low histamine on the seizure development of pentylenetetrazol (PTZ)-induced kindling in rats. METHODS: After 14 d of feeding on a low histamine diet (LH, containing 0.145 mumol/g of histamine), the rats were chemically kindled by repeated intraperitoneal injection of a subconvulsant dose of PTZ (35 mg/kg) once every 48 h, and seizure activity of kindling was recorded for 30 min. Histamine in brain samples was analyzed using a high performance liquid chromatography system with a fluorescence spectrofluorometer. RESULTS: The LH diet induced an increase in seizure response (seizure susceptibility) to the first trial of PTZ, and resulted in facilitation of subsequent PTZ kindling process (seizure development). The histamine levels in the cortex, hippocampus, and hypothalamus of LH-treated rats decreased significantly and these changes correlated well with seizure behavior (r = 0.875, 0.651, and 0.796, respectively). In addition, chronic kindled seizures resulted in a significant increase of the histamine content in the cortex and hypothalamus in the LH-fed groups. CONCLUSION: These findings indicate that the histamine in daily food could influence the brain histaminergic function, and play an important role in regulating seizure susceptibility.

Animals↗
PubMed2005

Histidine enhances carbamazepine action against seizures and improves spatial memory deficits induced by chronic transauricular kindling in rats.

AIM: To investigate whether histidine can enhance the anticonvulsant efficacy of carbamazepine (CBZ) and simultaneously improve the spatial memory impairment induced by transauricular kindled seizures in Sprague-Dawley rats. METHODS: Chronic transauricular kindling was induced by repeated application of initially subconvulsive electrical stimulation through ear-clip electrodes once every 24 h until the occurrence of 3 consecutive clonic-tonic seizures. An 8-arm radial maze (4 arms baited) was used to measure spatial memory, and histamine and gamma-amino-butyric acid levels were measured by high performance liquid chromatography (HPLC). RESULTS: Chronic transauricular kindling produced a significant impairment of spatial memory and a marked decrease in histamine content in the hypothalamus, the brainstem, and the hippocampus. Injection of histidine (1000 mg/kg or 1500 mg/kg, ip) significantly inhibited transauricular kindled seizures. Injection of histidine at lower doses (200 mg/kg or 500 mg/kg, ip) had no appreciable anticonvulsant effect when administered alone, whereas it significantly potentiated the protective effects of CBZ against kindled seizures. CBZ had no ameliorative effect on memory deficit, but, in contrast, histidine (200 mg/kg or 500 mg/kg, ip) alone or co-administered with CBZ significantly ameliorated the memory deficits induced by the seizures. CONCLUSION: Chronic transauricular kindling is a very useful animal model for evaluating memory deficits associated with epilepsy, and histidine has both a potentiate effect on the anticonvulsant efficacy of CBZ and an ameliorative effect on the spatial memory deficits induced in this model. Histidine at a specific dosage range might serve as a beneficial adjuvant for the clinical treatment of epilepsy, especially when accompanied by impaired spatial memory.

Animals↗
PubMed2005

Inhibitory effect of acetamide-45 on airway inflammation and phosphodiesterase 4 in allergic rats.

AIM: To determine the effects of acetamide-45 on respiratory function, airway inflammation, and the activity of phosphodiesterase 4 (PDE4) in allergic rats. METHODS: Rats were sensitized by a single intramuscular injection with ovalbumin (OVA) and were challenged with ovalbumin applied by using an aerosol repeatedly for 7 d after 2 weeks. Acetamide-45 at concentrations of 5, 10, or 30 mg/kg was then administered by intraperitoneal injection. Changes in dynamic lung compliance and lung resistance, the accumulation of inflammatory cells in bronchoalveolar lavage, PDE4 activity, and the concentration of interleukin-4 in rat lung tissue were determined. RESULTS: Seven days of treatment with acetamide-45 prevented eosinophil accumulation in allergic rats. At doses of 5, 10, and 30 mg/kg, acetamide-45 decreased lung resistance to 0.20+/-0.04, 0.25+/-0.07, and 0.22+/-0.05 cmH2O.s(-1).mL(-1), respectively (P<0.05 vs OVA), and it also increased dynamic lung compliance to 0.41+/-0.07, 0.39+/-0.06, and 0.42+/-0.09 mL/cmH2O (P<0.05 vs OVA). After being treated with different doses of acetamide-45, the PDE4 activities in lung tissue were 281+/-55, 273+/-57, and 238+/-36 nmol.g(-1).min( -1) (P<0.05 vs OVA), and the concentrations of interleukin-4 in lung tissue were 6.22+/-1.13, 5.95+/-1.20, and 5.68+/-2.20 microg/protein (P<0.05 vs OVA). CONCLUSIONS: Acetamide-45 was found to improve respiratory function and inhibit airway inflammation in this animal model, and the PDE4 activity of lung tissue was obviously inhibited. Acetamide-45 was an effective anti-inflammatory agent in respiratory inflammation, and the mechanism of its action might depend on inhibition of PDE4.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed2005

Histamine ameliorates spatial memory deficits induced by MK-801 infusion into ventral hippocampus as evaluated by radial maze task in rats.

AIM: To investigate the role of histamine in memory deficits induced by MK-801 infusion into the ventral hippocampus in rats. METHODS: An 8-arm radial maze (4 arms baited) was used to assess spatial memory. RESULTS: Bilateral ventral intrahippocampal (ih) infusion of MK-801 (0.3 microg/site), an N-methyl-D-aspartate (NMDA) antagonist, impaired the retrieval process in both working memory and reference memory. Intrahippocampal injection of histamine (25 or 50 ng/site) or intraperitoneal (ip) injection of histidine (25, 50 or 100 mg/kg) markedly ameliorated the spatial memory deficits induced by MK-801. Both the histamine H1 antagonist pyrilamine (0.5 or 1.0 microg/site, ih) and the H2 antagonist cimetidine (2.5 microg/site, ih) abolished the ameliorating effect of histidine (100 mg/kg, ip) on reference memory deficits, but not that on working memory deficits induced by MK-801. CONCLUSION: The results indicate that histamine in the ventral hippocampus can ameliorate MK-801-induced spatial memory deficits, and that histamine's effect on reference memory is mediated by postsynaptic histamine H1 and H2 receptors.

Animals↗
PubMed2005

Visual recognition memory is related to basic expression level of NMDA receptor NR1/NR2B subtype in hippocampus and striatum of rats.

AIM: To examine the basic expression levels of N-methyl-D-aspartate (NMDA) receptor NR1 and NR2B subunits in six brain regions of Sprague-Dawley (SD) rats with different visual recognition memory. METHODS: Rats were tested by a novel-object-recognition model and grouped into the high and the low visual recognition memory groups. The expression levels of NR1 and NR2B subunits in the cortex, hippocampus, striatum, amygdala, diencephalon, and olfactory bulb were measured by semiquantitative immunoblotting. RESULTS: The NR1 and NR2B subunit protein levels in the hippocampus of the high visual recognition memory group were 35.9% (P<0.01) and 53.4% (P<0.05) higher respectively than those in the low group. In addition, the NR2B level in the striatum in the high visual recognition memory group was 25.0% (P<0.05) higher than that in the low one. However, no significant difference was found in the levels of the subunits between the two groups in other brain regions. CONCLUSION: The visual recognition memory in rats is related to the basic expression level of NMDA receptor NR1/NR2B subtype in the hippocampus and striatum.

Animals↗
PubMed2005

Protective effects of baicalin on oxygen/glucose deprivation- and NMDA-induced injuries in rat hippocampal slices.

Baicalin is a flavonoid derivative from Scutellaria baicalensis Georgi with various pharmacological effects. Recently, the neuroprotective effect of baicalin was reported. To confirm this effect and explore the possible mechanism, we have investigated the protective effect of baicalin on ischaemiclike or excitotoxic injury and the activation of protein kinase C alpha (PKC(alpha)) in rat hippocampal slices. In-vitro ischaemic-like injury was induced by oxygen/glucose deprivation (OGD) and the excitotoxic injury by N-methyl-D-aspartate (NMDA). The viability and swelling of the slices were detected by triphenyltetrazolium chloride (TTC) staining and image analysis of light transmittance (LT), respectively. The translocation of PKC(alpha) was measured by immunoblotting. Baicalin was added during both injuries. Baicalin (0.1, 1, and 10 micromol L(-1)) concentration-dependently inhibited OGD-induced viability reduction and acute neuron swelling, and inhibited the increased portion of PKC(alpha) present in the membrane fraction over the total PKC(alpha). Baicalin ameliorated NMDA-induced viability reduction (not LT elevation) and inhibited the NMDA-increased membrane portion of PKC(alpha) at 1 micromol L(-1). We concluded that baicalin had a protective effect on ischaemic-like or excitotoxic injury in rat hippocampal slices, which might have been partly related to inhibition of PKC(alpha) translocation.

Animals↗
PubMed2005

Increased expression of aquaporin-4 in human traumatic brain injury and brain tumors.

OBJECTIVE: To characterize the expression of aquaporin-4 (AQP4), one of the aquaporins (AQPs), in human brain specimens from patients with traumatic brain injury or brain tumors. METHODS: Nineteen human brain specimens were obtained from the patients with traumatic brain injury, brain tumors, benign meningioma or early stage hemorrhagic stroke. MRI or CT imaging was used to assess brain edema. Hematoxylin and eosin staining were used to evaluate cell damage. Immunohistochemistry was used to detect the AQP4 expression. RESULTS: AQP4 expression was increased from 15 h to at least 8 d after injury. AQP4 immunoreactivity was strong around astrocytomas, ganglioglioma and metastatic adenocarcinoma. However, AQP4 immunoreactivity was only found in the centers of astrocytomas and ganglioglioma, but not in metastatic adenocarcinoma derived from lung. CONCLUSION: AQP4 expression increases in human brains after traumatic brain injury, within brain-derived tumors, and around brain tumors.

Adult↗
PubMed2005

[Inhibition of acetamide-45 on airway smooth muscle contraction induced by electric field stimulation and methacholine in vitro].

OBJECTIVE: To investigate the effects of the new antiallergic agent N-(pyridin-4-yl)-(indol-3-yl) acetamide-45 (acetamide-45) on electric field stimulation (EFS)-and methacholine-induced contraction of airway smooth muscle in vitro. METHODS: Contractions were induced by EFS in isolated trachea and bronchus of rats or by cumulative methacholine concentrations in isolated trachea of guinea pigs. Changes in isometric force of isolated airway smooth muscle were measured by force transducers and recorded on a multi-channel polygraph recorder. RESULTS: Acetamide-45 inhibited the contraction induced by EFS in isolated rat airway. The IC50 was 10.74 (95% CI 8.87-13.00) micromol.L(-1) and 18.83 (95% CI 14.57-24.33) micromol.L(-1) in tracheae and bronchi, respectively. Acetamide-45 also inhibited methacholine-induced contractile response of isolated guinea pig trachea in a concentration-dependent manner. At concentrations of 3, 10, 30 micromol.L(-1) acetamide-45 significantly decreased maximal contractile response of methacholine by 24.6%-43.2% and increased EC50 of methacholine by 3.1-to 21.4-fold. CONCLUSION: Acetamide-45 inhibits EFS-or methacholine-induced contraction of isolated airway smooth muscle, and these effects might be non-specific inhibition on cholinergic receptor.

Acetamides↗
PubMed2005

Configuration of a new bioartificial liver support system and in vitro evaluation of its functions.

The aim of this study was to configure a new bioartificial liver (BAL) support system and evaluate its functions in vitro. Chinese experimental miniature pig hepatocytes were isolated by an in situ recirculating collagenase perfusion method and were cultured in serum-free medium with restriction attachment and spinner technique to form hepatocyte spheroid suspensions containing 1.0 x 10(10) hepatocytes. The BAL support system was configured by inoculating the hepatocyte spheroids into the cell circuit of a hollow fiber bioreactor (BIOLIV A3A, Cell Biotech Limited, HK, China). The number and viability of hepatocytes, the levels of alanine aminotransferase (ALT), total bilirubin (TBi), and albumin (ALB) in the circulating hepatocyte suspension and RPMI-1640 medium, and lidocaine metabolism were determined during 6 hr of circulation in the BAL devices. Independent experiments were performed 5 times. There were no significant changes in the number and viability of the hepatocytes during the circulation period. The BAL support system demonstrated substantial albumin synthesis and lidocaine metabolism. The results indicate that the new BAL support system has the ability to perform liver functions and could be used to treat liver failure or provide temporary liver support in patients who are candidates for liver transplantation.

Animals↗
PubMed2005

[Proliferation and apoptosis in vitro of umbilical cord blood CD34+CD38- hematopoietic early progenitor cells].

To cultivate CD34(+)CD38(-) cells isolated from umbilical cord blood of healthy puerperal women over a longer-period of time for observation of cell division, proliferation, apoptosis, and effects of stem cell factor on the growth of CD34(+)CD38(-) cells, with flow cytometry, CD34(+)CD38(-) cells were isolated from umbilical cord blood of 10 healthy puerperal women and cultivated in stem cell media with supplement of IL-3, IL-6, GM-CSF, EPO, IGF-1 and SCF 6 kinds cell growth stimulating factors for six months. The cell growth curves were established. The effects of stem cell factor on the growth of CD34(+)CD38(-) cells and cell apoptosis were investigated with the single cell gel electrophoresis technique and flow cytometry method, respectively. The results showed that CD34(+)CD38(-) cells isolated from umbilical cord blood were capable of proliferating after being cultivated in vitro over a longer-period of time with no evidence of the presence of excessive apoptosis. In conclusion, under appropriate culture conditions, CD34(+)CD38(-) hematopoietic early progenitor cells from umbilical cord blood can serve as a resource providing a large amount of primitive cells for transplantation therapy after a longer period of cultivation and proliferation in vitro.

ADP-ribosyl Cyclase 1↗
PubMed2005

[Karyotyping and immunophenotyping analyses of the CD34+ CD38- cells isolated from human umbilical cord blood].

OBJECTIVE: To cultivate hematopoietic stem/progenitor cells (CD34(+)CD38(-)) isolated from umbilical cord blood (UCB) long for the observation of cell growth and expansion in vitro, surface marker expression, and chromosomal complements. METHODS: By flow cytometry CD34-FITC and CD38-PE labeled CD34(+) and CD38(-) stem/progenitor cells were isolated from UCB. The cells were cultivated in vitro for 6 months in a stem cell culture system with addition of six kinds of cell growth factors (IL-3, IL-6, GM-CSF, Epo, SCF, IGF-1). One month after cultivation, cultured cells were investigated for surface marker expression by flow cytometry and karyotype by G banding method. RESULTS: After 7-12 days cultivation, the CD34(+)CD38(-) stem/progenitor cells began proliferation. The proliferation rate and the peak proliferation duration were greater in 1 cell/well cultivation conditions than in 10 cells/well. The cells remained CD34(+)CD38(-) and their karyotypic characteristics remained unchanged. CONCLUSION: CD34(+)CD38(-) stem/progenitor cells from UCB may provide a larger than original amount of stem/progenitor cells for transplantation after long-term cultivation in vitro.

ADP-ribosyl Cyclase 1↗
PubMed2005

[Spiral CT findings of pulmonary infection induced by intravenous injection of heroin].

OBJECTIVE: To investigate spiral CT findings of pulmonary infection induced by intravenous injection of heroin. METHODS: The clinical data and spiral CT findings of 21 patients with pulmonary infection due to intravenous injection of heroin were analyzed retrospectively. RESULTS: Pulmonary lesions were detected in all these cases in the initial examination by spiral CT plain scan, including pneumatocele in 13 (61.9%), pulmonary cavity in 13 (61.9%), pulmonary consolidation in 15 (71.4%), and plural lesions in 8 cases (38.1%) of which 7 (33.3%) had plural effusion and 1 (0.48%) had encapsulated hydropneumothorax. Three cases had only one of the lesions and 18 had at least 2 of them. The CT images in each case were compared with X-ray film, and the latter displayed abnormalities in 20 cases (95.2%). X-ray failed to detect the lesions in 1 case (4.8%), in which pneumatocele was found in CT images. CONCLUSION: The pulmonary lesions of pulmonary pneumatocele, cavity, consolidation, and plural lesions are specific CT manifestations of hematogenous pulmonary suppurative infection induced by intravenous injection of heroin.

Adult↗
PubMed2005

[Transient expression of GUS gene controlled by different regulator sequences in rice and Populus tomrutosa].

GUS gene controlled by several kinds of regulator sequences (promoters, TMVOmega enhancer and fragments of 18S rRNA gene from Arabidopsis thaliane) were introduced into the calli of rice and Populus tomrutosa respectively by gene gun. The transient expression of GUS gene in the calli of rice and P. tomrutosa was investigated. The results showed: (1) in the calli of rice, Ubil promoter was the most effective one among the several regulator sequences and CaMV35S with fragments of 18S rRNA gene is the least effective one; (2) in the calli of P. tomrutosa, CaMV35S promoter with 18S rDNA fragments was the most effective one among the several regulator sequences; and (3) tandem CaMV35S-Ubil promoter with TMVOmega sequence could not enhance significantly the expression of GUS gene in the calli of rice and P. tomrutosa.

Biolistics↗
PubMed2005

[Diterpenes constituents of Tripterygium wilfordii].

AIM: To study the chemical constituents of Tripterygium wilfordii Hook. F. METHODS: Various column chromatographies with silica gel were used for the isolation and purification. The structures of compounds were established on the basis of its IR, MS, UV, 1H NMR, 13C NMR and HRMS, 1H-1H COSY, 1H-13C COSY and NOESY. RESULTS: Four diterpenoids were isolated: 16-hydroxytriptolide (I), triptolidenol (II), tripdiolide (III), 2-epitripdiolide (IV). CONCLUSION: Compound IV is a new diterpenoid.

Diterpenes↗
PubMed2004

2-methoxyestradiol inhibits hypoxia-inducible factor 1alpha, tumor growth, and angiogenesis and augments paclitaxel efficacy in head and neck squamous cell carcinoma.

PURPOSE: Head and neck squamous cell carcinomas have been reported to overexpress hypoxia-inducible factor (HIF)-1alpha, a transcription factor that promotes expression of angiogenesis factors and resistance to programmed and therapy-induced cell death. 2-Methoxyestradiol (2ME2) is a natural compound with HIF-1alpha inhibitory activity that is currently being evaluated in phase 1 and 2 clinical trials for advanced solid tumors and multiple myeloma. To our knowledge, this is the first study to evaluate the effects of 2ME2 in head and neck squamous cell carcinoma. EXPERIMENTAL DESIGN: In the present study, we investigated the effects of 2ME2 alone and in combination with paclitaxel, an active agent in recurrent or advanced head and neck squamous cell carcinoma. RESULTS: 2ME2 exhibited antiproliferative and cytotoxic effects in a panel of five head and neck squamous cell carcinoma cell lines in the 0.5 to 10 micromol/L range, including induction of G2-M blockade, caspase-3/7 activation, and apoptosis at 48 hours. 2ME2 resulted in decreased nuclear HIF-1alpha-binding activity and affected the expression of downstream genes, such as bid, a proapoptotic bcl-2 family member, and vascular endothelial growth factor, a proangiogenic cytokine. The up-regulation of Bid (57.5% at 12 hours, P < 0.0006) and inhibition of vascular endothelial growth factor secretion (57.7% at 24 hours, P < 0.015; and 50.3% at 48 hours, P < 0.0006) could be partially attributed to the effects on HIF-1alpha, because HIF-1alpha small interfering RNAs produced similar effects. Finally, in vivo, in a xenograft model of head and neck squamous cell carcinoma using UM-SCC-11A cells, 2ME2 exhibited antitumor and antiangiogenic activity, as measured by CD31 immunostaining. CONCLUSIONS: These results provide support for the use of 2ME2 in combination with paclitaxel for the treatment of recurrent or advanced head and neck squamous cell carcinoma.

2-Methoxyestradiol↗
PubMed2004

Liquid crystalline behavior of a semifluorinated oligomer.

Monte Carlo simulations with a coarse-grained model were performed to study the microstructure of a semifluoroalkane C20 diblock oligomer [F(CF(2))(10)(CH(2))(10)H]. The coarse-grained model adopted is based on previously reported united-atom force fields for alkanes and perfluoroalkanes and was first validated by simulating the phase behavior of a mixture of hexane and perfluorohexane. These preliminary simulations established the need of a significant correction factor in the Berthelot mixing rule between alkane and perfluoroalkane groups. Using such a force field, the semifluorinated C20 oligomer liquid was simulated using efficient Monte Carlo moves to sample different molecular arrangements and box dimensions so as to allow different layering structures to form. In qualitative agreement with experimental observations, a smectic-to-isotropic phase transition occurs as temperature is increased but the transition point and the structure of the smectic phase depend on the stiffness of the torsional potential and the model of van der Waals interactions adopted. We identify two smectic phases LC1' and LC2', whose structures do not agree with those that have been postulated before to explain x-ray diffraction data, namely, LC1 and LC2. LC1' has a layer spacing similar to LC1 but the antiparallel packing is not observed with individual chains but with groups of chains producing a checkerboard pattern. LC2' has fully microsegregated blocks such as LC2 but the alkyl tails are not fully stretched or interdigitated. Despite these inconsistencies, and considering that reported experimental data also reveal the presence of mixed phases, the simulated structures suggest other plausible ways how the semifluorinated chains could pack and microsegregate to best negotiate energetic and entropic constraints.

Journal Article↗
PubMed2004

Minocycline protects PC12 cells from ischemic-like injury and inhibits 5-lipoxygenase activation.

Minocycline protects animals against cerebral ischemia by inhibiting inflammation. To determine whether minocycline protects PC12 cells from in vitro ischemic-like injury and affects pro-inflammatory 5-lipoxygenase activation, the cell viability and 5-lipoxygenase translocation to nuclear membrane were observed after oxygen-glucose deprivation (OGD). We found that OGD reduced cell viability, which was attenuated by minocycline and 5-lipoxygenase inhibitor caffeic acid. 5-Lipoxygenase protein was detected in PC12 cells by immunohistochemical and Western blot analyses. OGD induced 5-lipoxygenase translocation to nuclear membranes, which was abolished by minocycline and caffeic acid. Thus, minocycline can protect PC12 cells from in vitro ischemic-like injury, and this effect may be partly related to the inhibition of 5-lipoxygenase activation.

Animals↗