PubMed Health⌕ Search

Biomedical subjects

H Zhang

Publications and source records attributed to H Zhang.

At least 559 records · Page 31Linked to original sources
PubMed2000

[Effects of microwave radiation on lipid peroxidation and the content of neurotransmitters in mice].

Male LACA mice were exposed to 900 MHz microwaves at the power densities of 0,1,2 and 5 mW/cm2. The resulting specific absorption rates(SARs) were 0, 0.22, 0.44 and 1.10 W/kg respectively. Animals were exposed at the dosage of 1 hour a day for 35 days. The results showed that the activity of glutathione peroxidase (GSH-Px) increased and the concentration of malondialdehyde (MDA) decreased in blood, and the concentration of noradrenaline (NE) increased in brains in the microwave exposed groups at 1 mW/cm2 compared with the sham-exposed group. But no significant changes were found in the microwave exposed groups at 2 and 5 mW/cm2. No significant changes of the concentrations of 5-hydroxytryptamine(5-HT), 5-hydroxyindole acetic acid(5-HIAA) and dopamie(DA) in brains were found.

Animals↗
PubMed2000

[Effect of typical aldehyde pollutants on the DNA damage of spleen lymphocytes of mice].

The DNA damage of spleen lymphocytes induced by three typical aldehyde pollutants was studied in vitro with microgel single cell electrophoresis assay (comet assay). It showed that the comet cells induced by the three chemicals were observed, and the dose-dependent relations were existed. It suggested that the three aldehydes could induce DNA strand breakage.

Acetaldehyde↗
PubMed2000

A synthetic peptide initiates Gerstmann-Sträussler-Scheinker (GSS) disease in transgenic mice.

The molecular basis of the infectious, inherited and sporadic forms of prion diseases is best explained by a conformationally dimorphic protein that can exist in distinct normal and disease-causing isoforms. We identified a 55-residue peptide of a mutant prion protein that can be refolded into at least two distinct conformations. When inoculated intracerebrally into the appropriate transgenic mouse host, 20 of 20 mice receiving the beta-form of this peptide developed signs of central nervous system dysfunction at approximately 360 days, with neurohistologic changes that are pathognomonic of Gerstmann-Sträussler-Scheinker disease. By contrast, eight of eight mice receiving a non-beta-form of the peptide failed to develop any neuropathologic changes more than 600 days after the peptide injections. We conclude that a chemically synthesized peptide refolded into the appropriate conformation can accelerate or possibly initiate prion disease.

Amino Acid Sequence↗
PubMed2000

Enteroviral capsid protein VP1 is present in myocardial tissues from some patients with myocarditis or dilated cardiomyopathy.

BACKGROUND: There are still discrepancies in the association of enterovirus and myocardial disease, partially due to lack of data on the detection of virus antigens in tissues. It is desirable to localize enteroviral antigens so as to establish a link between the two and to study mechanisms of virus persistence. METHODS AND RESULTS: Nineteen fixed explanted or postmortem myocardial samples were obtained from patients with myocarditis or dilated cardiomyopathy (DCM). Control samples were collected from 11 subjects who had died accidentally or of noncardiovascular disease. Viral antigen was detected by an improved immunohistochemical technique using an enterovirus group-specific antibody to viral capsid protein VP1. Nine of 11 myocarditis cases (81.8%) and 6 of 8 DCM cases (75%) were positive. Signals were localized in the cytoplasm of myocytes. Intense immunostaining was observed in acute myocarditis, whereas VP1 was detected in scattered myocytes in chronic myocarditis or DCM. Enteroviral RNA was detected in 6 of 11 myocarditis samples (54.5%) and 3 of 8 DCM samples (37.5%) by the reverse transcription-nested polymerase chain reaction, correlating with antigen detection (kappa=0.6+/-0.21). Neither viral antigen nor RNA was detected in any controls. CONCLUSIONS: Our findings demonstrate a direct link between enterovirus infection and some myocarditis or DCM cases. The pattern of VP1 detection may correlate with disease stage and severity. The data suggest that viral protein synthesis may be involved in persistent enterovirus infection in the pathogenesis of DCM.

Adolescent↗
PubMed2000

Profiling neurosteroids in cerebrospinal fluids and plasma by gas chromatography/electron capture negative chemical ionization mass spectrometry.

A quantitative method for the determination of allopregnanolone (5alpha,3alpha-THP) and related neurosteroids in CSF and plasma was established using gas chromatography/electron capture negative chemical ionization mass spectrometry (GC/ECNCI/MS). Neurosteroids were converted to carboxymethoxime, pentafluorobenzyl and trimethylsilyl derivatives and detected as intense (M-181)(-) fragment ions generated under the negative ion chemical ionization process. The response curves constructed using d(4)-dihydrotestosterone (DHT) and d(4)-5alpha,3alpha-THP as internal standards showed linearity in the concentration range of 10-1000 pg/ml. The variation of response ratios determined against internal standards over a 2-month period was less than 10%. Instrumental detection limits for most neurosteroids were in the low picogram range with the exception of progesterone and dihydroprogesterone (DHP) which were detected with approximately 10 times less sensitivity in comparison to other steroids. In conjunction with solid-phase extraction, this method allowed the quantification of at least four neurosteroids, including androsterone, testosterone, 5alpha,3alpha-THP, and pregnenolone in 1-2 ml of human cerebrospinal fluid (CSF). While the level of 5alpha, 3alpha-THP in human CSF was comparable to that in the human plasma, other steroid levels were significantly lower. Although individual CSF and plasma samples showed widely varying neurosteroid levels, species specificity appeared to exist. The levels of 5alpha, 3alpha-THP and pregnenolone in human CSF were higher than those of monkey CSF where these steroids were often not detected with our current detection limit. In comparison to human plasma, rat plasma samples contained considerably lower levels of androsterone and pregnenolone. Among THP stereoisomers, 5beta,3alpha-THP and 5alpha, 3beta-THP were observed only in human plasma, while 5beta,3beta-THP was detected only in rat plasma.

Adult↗
PubMed2000

Preliminary findings of antistreptococcal antibody titers and basal ganglia volumes in tic, obsessive-compulsive, and attention deficit/hyperactivity disorders.

BACKGROUND: Previous studies have provided preliminary serological evidence supporting the theory that symptoms of tic disorders or obsessive-compulsive disorder (OCD) may be sequelae of prior streptococcal infection. It is unclear, however, whether previously reported associations with streptococcal infection were obscured by the presence of diagnostic comorbidities. It is also unknown whether streptococcal infection is associated in vivo with anatomical alterations of the brain structures that have been implicated in the pathophysiology of these disorders. METHODS: Antistreptococcal antibody titers were measured in 105 people diagnosed as having CTD, OCD, or attention-deficit/hyperactivity disorder (ADHD) and in 37 community controls without a disorder. Subjects were unselected with regard to their history of streptococcal exposure. Basal ganglia volumes were measured in 113 of these subjects (79 patients and 34 controls). RESULTS: A DSM-IV diagnosis of ADHD was associated significantly with titers of 2 distinct antistreptococcal antibodies, antistreptolysin O and anti-deoxyribonuclease B. These associations remained significant after controlling for the effects of CTD and OCD comorbidity. No significant association was seen between antibody titers and a diagnosis of either CTD or OCD. When basal ganglia volumes were included in these analyses, the relationships between antibody titers and basal ganglia volumes were significantly different in OCD and ADHD subjects compared with other diagnostic groups. Higher antibody titers in these subjects were associated with larger volumes of the putamen and globus pallidus nuclei. CONCLUSIONS: These findings suggest that the prior reports of an association between antistreptococcal antibodies and either CTD or OCD may have been confounded by the presence of ADHD. They also support the hypothesis that in susceptible persons who have ADHD or OCD, chronic or recurrent streptococcal infections are associated with structural alterations in basal ganglia nuclei.

Adult↗
PubMed2000

Atmospheric pressure ionization time-of-flight mass spectrometry coupled with fast liquid chromatography for quantitation and accurate mass measurement of five pharmaceutical drugs in human plasma.

The quantitative determination and accurate mass measurement of five tricyclic amine pharmaceutical drugs (doxepin, desipramine, imipramine, amitriptyline and trimipramine) fortified in human plasma within a per sample run time of 18 s was accomplished by atmospheric pressure ionization (API) time-of-flight (TOF) mass spectrometry using a turboIonspray liquid chromatography/mass spectrometry (LC/MS) interface coupled with high-performance liquid chromatography (HPLC). The relatively short HPLC separation (18 s) was achieved using a short C18 column (15 x 2.1 mm i.d.) with a high aqueous mobile phase maintained at a flow-rate of 1.4 ml min(-1). An acquisition speed of 0.2 s per spectrum accommodates these fast separation conditions. This method employs a one-step liquid-liquid extraction procedure to isolate the five tricyclic amines from biological matrix components The overall extraction recovery was 75% for desipramine and >90% for the other four tricyclic amines. The lower level of quantitation was 1-2 ng ml(-1) for each compound. The calibration curve was linear from 2 to 100 ng ml(-1) for desipramine and from 1 to 50 ng ml(-1) for the other four tricyclic amines. A deuterated internal standard, imipramine-d3, was used for all five tricyclic amines. Acceptable intra- and inter-assay precision (1.0-17.7%) and accuracy (0.2-14.5%) were obtained. The linear dynamic range was extended to 200 based on a software upgrade for correcting ion current detection saturation. The accurate masses of the five tricyclic amines were determined by on-line LC/TOFMS analyses of biological extracts using two-point internal mass calibration. This was done by infusing a reference standard, Jeffamine D230, post-column into the HPLC effluent. All results showed a mass error not greater than 9 ppm for all the target compounds. These results were obtained from both synthetic mixtures when as little as 100 pg were injected or extracts of spiked human plasma samples with analytical concentration as low as 5 ng ml(-1). The factors influencing accurate mass measurements are discussed.

Antidepressive Agents, Tricyclic↗
PubMed2000

New chiral catalysts for reduction of ketones.

The condensation of o-(diphenylphosphino)benzaldehyde and various chiral diamine gives a series of diimino-diphosphine tetradentate ligands, which are reduced with excess NaBH4 in refluxing ethanol to afford the corresponding diaminodiphosphine ligands in good yield. The reactivity of these ligands toward trans-RuCl2(DMSO)4 and [Rh(COD)Cl]2 had been investigated and a number of chiral Ru(II) and Rh(I) complexes with the PNNP-type ligands were synthesized and characterized by microanalysis and IR, NMR spectroscopic methods. The chiral Ru(II) and Rh(I) complexes have proved to be excellent catalyst precursors for the asymmetric transfer hydrogenation of aromatic ketones, leading to optically active alcohols in up to 97% ee.

Chemistry↗
PubMed2000

Use of classification trees for association studies.

We propose the use of classification trees for association studies. This approach is applied to a data set from Genetic Analysis Workshop 9 (GAW9), and our analysis precisely identified two disease alleles. Our purpose is to demonstrate the great potential of tree-based analyses for genetic studies, and discuss some issues that warrant further investigation.

Alleles↗
PubMed2000

Aconiti tuber (Bushi) improves microcirculatory disturbances induced by endotoxin in rats.

The present study investigated the effects of processed Aconiti tuber (TJ-3022, Tsumura-shuchi-bushi), a traditional herbal medicine (Kampo), on microcirculatory disturbances induced by endotoxin in the rat mesentery. The changes in arteriolar diameter, the velocity of red blood cells in arterioles and the venular microcirculation after endotoxin injection (6 mg/kg, iv) were observed using videomicroscopy. The mean arterial pressure and heart rate were monitored continuously during the experiments. TJ-3022 prevented significantly the decrease of mean arterial pressure, controlled the reduced velocity and apparently also inhibited leukocyte extravasation across venules. However, there were no significant changes in the arteriolar diameter and the heart rate between the groups treated with and without TJ-3022. The results indicate that processed Aconiti tuber (TJ-3022) has protective effects in improving microcirculatory disturbances induced by endotoxin in rat mesentery.

Animals↗
PubMed2000

Expression, purification, and characterization of human recombinant thrombopoietin in Chinese hamster ovary cells.

Thrombopoietin (TPO) is a primary regulator of megakaryocytopoiesis, a process through which megakaryocytes proliferate and mature into platelets. Recombinant human TPO (rhTPO) was expressed in Chinese hamster ovary (CHO) cells and purified from the culture medium. The cDNA encoding full-length TPO, including the native signal peptide sequence, was amplified by PCR from a human fetal liver cDNA library. The product was cloned into a mammalian expression vector under the control of the SV40 early promoter and enhancer. Secreted rhTPO was purified in three conventional chromatography steps. It migrates on SDS-PAGE as a broad band, characteristic of a heavily glycosylated protein, with an average molecular mass of 85 kDa. rhTPO expressed in CHO cells is biologically active in vitro as demonstrated by its ability to stimulate the proliferation of a megakaryocytic cell line and to trigger the JAK/STAT signal transduction pathway. rhTPO also shows activity in vivo as judged by the elevation of platelet count in treated mice.

Animals↗
PubMed2000

Effect of polypeptide CH50 on macrophage activation in vivo and anti-tumor function.

The main features of CH50, a recombinant polypeptide of human fibronectin, activating macrophages in vivo and its anti-tumor function were investigated. After injection of CH50 and(or) transfection of IFN-gamma gene in vivo, several kinds of factors produced by macrophages were determined and the growth of tumor in vivo was measured. CH50 could enhance the production of such factors as NO, TNF and IL-1 by macrophages, but the activation of macrophages was relatively slow when CH50 was used in vivo alone. CH50 and IFN-gamma could synergistically activate macrophages rapidly in vivo no matter whether the injection of CH50 or the transfection of IFN-gamma gene was performed first. Injection of CH50 alone inhibited the formation of tumor nodes in a dose-dependent manner. Low dose of CH50 could strongly inhibit the formation of tumor nodes less than 1 mm, while high dose of CH50 could inhibit those more than 1 mm. A stronger inhibition on the growth of tumor in vivo was obtained by the synergistic effect of CH50 and IFN-gamma. CH50 and IFN-gamma, as double-signal factors for activation of macrophages, will be potentially useful in tumortherapy.

Animals↗
PubMed2000

Study on P16 gene in acute leukemia.

To study the change of suppressing cancer gene P16 in acute leukemia, the P16 antigen expression of leukemia cell surfaces in 61 cases were investigated with ABC assay and gene structural defects in 51 cases of acute leukemia were examined with multiple comparative PCR method. It was found that antigen expression of P16 in leukemia was obviously lower than that innormal subjects (P < 0.001). At the same time, antigen expression in All was lower than that AML (P < 0.05). No significant difference was found between the complete remission (CR) and non-remission (NR) subjects from AML and ALL groups (P > 0.05). THe exon 2 of P16 gene showed homozygous deletion only inn 4 cases out of 30 cases in ALL. No structural defect was revealed in 21 cases of AML. It was suggested that expression defect of P16 gene was a main cause in development and progression of acute leukemia, and structural defect of exon 2 was not a primary molecular event.

Adolescent↗
PubMed2000

Construction of eukaryotic expressing vector pCH503 of CH50 and its chemotaxis and anti-tumor function by expression in vivo in mice.

An eukaryotic expressing vector that expresses CH50, a recombinant polypeptide of human fibronectin, in mice was constructed, and its chemotactic and anti-tumor function by in vivo gene transfection was investigated. The plasmid was constructed by recombination techniques. The cDNA fragment coding CH50 polypeptide from a prokaryotic expressing vector of CH50 was ligated with 5'-terminal noncoding region and coding region of signal peptide of mouse IFN-gamma cDNA at 5' side and 3'-terminal noncoden region of human FN cDNA at 3' side. The recombinant cDNA was inserted into plasmid pREP8. The resulted expressing plasmid was designated as pCH503. The macrophages transfected with pCH503 in vivo and cultured in vitro could produce CH50. The expressed product was identified by heparin-affinity chromatography and SDS-PAGE. By counting and Giemsa-staining of coeliac cells and histotomy and staining of muscle tissue, the chemotaxis on immune cells was observed after transfection of pCH503 either in peritoneal cavity or in muscle. The inhibition of gene transfection of pCH503 on melanoma was observed in mice. The number of melanoma nodes in mice was reduced by 50%-60% after coeliac transfection with pCH503. The pCH503, an eukaryotic expressing vector of CH50, can express in vivo in mice. The transfection of pCH503 in vivo has the chemotaxis on immune cells and can inhibit the formation of tumor nodes, suggesting that plasmid pCH503 is potentially useful in combined treatment of tumor.

Animals↗
PubMed2000

Augmentation of recombinant CH50 polypeptide on the function of macrophages of mice during chemotherapy.

The immunosuppressive model of mice was made by intraperitoneal injection of cyclophosphamide. The effect of CH50, a recombinant polypeptide of human fibronectin, on macrophages of mice was observed. The results showed that continuous intraperitoneal injection of CH50 could prevent the reduction of the number of monocytes in periphery blood and abdominal cavity by chemotherapeutic agents, enhance the metabolic activity and cytotoxicity of macrophages and augment the proliferation of splenocytes. The results suggested that CH50 is a product which could be used to improve the efficacy of chemotherapy of tumors.

Adjuvants, Immunologic↗
PubMed2000

Fundamental study of hot spot detectability in 3-dimensional positron emission tomography.

The purpose of this study was to investigate the detectability of small hot lesions with the 3-dimensional transmission/emission (3D T/E) acquisition mode in FDG-PET scan. The correlation of target detectability, target size, target to non-target uptake ratio (T/N ratio) and standardized uptake value (SUV) were studied. Small hot lesions ranged from 4.4 mm to 36.9 mm in diameter were located in cylindrical phantom. The images of phantoms with a T/N ratio of 2.0, 4.0, 6.0, 8.0, 9.6, 13.2, 17.5, 23.8 and 30.3 were obtained with 2-dimensional transmission/emission (2D T/E) scan and 3D T/E scans. Targets in diameter more than 10.6 mm in diameter with an actual T/N ratio ranged from 6.0 to 30.3 could be identified on the images obtained with all the 2D T/E and 3D T/E acquisition modes. The detectability efficiency of small hot target in 2D T/E and 3D T/E scans was as same (77.8%). The T/N ratio of targets from 2D T/E images was 30% to 48.4% different to that from 3D T/E image, and the SUV of the target from the 2D T/E images was almost the same as that from 3D T/E images. This study revealed that 3D T/E scanning had similar hot spot detectability to 2D T/E scanning; 3D T/E and 2D T/E scanning had the same faculty for semiquantitative analysis using SUV. These findings may be helpful for the diagnosis and understanding of 3D T/E FDG-PET in hot lesion detection.

Fluorine Radioisotopes↗