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Biomedical subjects

J Zhao

Publications and source records attributed to J Zhao.

At least 397 records · Page 22Linked to original sources
PubMed1999

[Changes of lipids metabolism during gallstone formation in rabbit model and the effects on these changes by high density lipoprotein preparation injection].

To study the changes of lipids metabolism during gallstone formation and the effects fo the exogenous high-density lipoprotein (HDL) preparation on the formation of gallbladder stone in rabbit model in which the stones were induced by high-cholesterol (HC) diet. The plasma lipids, the bile cholesterol, the activity of plasma lecithine cholesterol acyltransferase (LCAT), the bile acids in both bile and plasma, and the incidence of stone formation were investigated in the control group, HC group, and HC + HDL group (in this group the rabbits were given HDL preparation intravenously regularly). The results showed that the lipids metabolic disorder was characterized by a large amount of cholesterol accumulated in the rabbit's body and when the liver cleaned the accumulated cholesterol, the ratio of biliary cholesterol to bile acids was significantly increased. The latter could cause the production of lithogenic bile. Thought HDL preparation could decrease hepatic cholesterol and increase the level of plasma HDL2-C and the activity of LCAT, it could not lower the incidence of gallstone formation. The results suggest that the HDL preparation had some effects on lipids metabolism, but no significant effect on gallstone formation in rabbit model has been evidenced, so the problem awaits further studies.

Animals↗
PubMed1999

[Change of high density lipoprotein receptor of hepatocyte during cholesterol gallstone formation in rabbit model].

In order to study the formation of cholesterol gallstone through rabbit model which was induced by high cholesterol diet (HCD), we investigated the high density lipoprotein receptor (HDLr) activities of hepatocytes, total bile acids and cholesterol of common duct bile at 1 week(1 w), 2 weeks(2 w), 3 weeks (3 w) and 4 weeks(4 w) in comparison with those of a control group respectively. The results were as follows: 1. The HDLr Bmax decreased and the kd value increased significantly (1 w group vs control group, P < 0.05); In 2 w group the two variables recovered to the level of control group; and after that, the HDLr Bmax increased and Kd value decreased markedly (3 w and 4 w groups vs control group, P < 0.05). 2. Total bile acids in bile increased slightly in 1 w group (vs control group, P > 0.05), then decreased in 2 w, 3 w and 4 w groups (4 w group vs control group, P < 0.05). 3. The concentration of cholesterol in bile increased gradually as the time of feeding HCD went on (3 w and 4 w groups vs control group, P < 0.05). The results demonstrated that owing to the intake of HCD with the passage of time, the activity of HDLr was up at the beginning and down gradually in the rest period. The change in concentrations of bile acids was similar to that of HDLr, and the concentration of cholesterol in bile was foreign to the change of HDLr. These results suggest that the decrease of HDLr activity may cause the absence of material for bile acids synthesis and it may play an important role in the formation of gallstone.

Animals↗
PubMed1999

[The immunohistochemistry and clinic study on surgical margin of laryngeal cancer].

OBJECTIVE: To probe into the safe incisal range of removing laryngectomy cancer determined from the albumen balance of cells. METHOD: LSAB or SABC of immunohistochemistry was applied, and three groups of samples with cancer tissue, nearby cancer tissue and distal cancer tissue of 36 primary laryngectomy cancer were tested by antibodies p16, p21, TGF-beta 1, PCNA and EGFR. RESULT: The difference of the positive rate with the five antibodies between the cancer group and the two side incisal group were very notable with P < 0.01 or P < 0.05, but which between nearby cancer tissue and distal cancer tissue were not notable with P > 0.05. The differences of the positive rates with 5 antibodied between high differentiation group and low differentiation group were notable with P < 0.05, and P < 0.05 with PCNA in the group whether the lymphonodi cervicales transmitted or not. The incisals for all the cases are beyond 5 mm, the recurerence rate is 3%. CONCLUSION: The 5 mm incisal for laryngectomy cancer is appropriate on the albumen cevel of cells.

Adult↗
PubMed1999

[Protein A tangential flow membrane chromatographic column used for immunoadsorption therapy].

Tangential flow membrane chromatographic column is a new model of immunoadsorption therapy from blood. The results showed that the structure of the column and the flowing channel had a little damages for blood cells. The relation of flow-rate and backpressure with water, plasma and blood individually as the fluid flowing through the column has been studied. It was observed that backpressures increased with fluid viscosity, when flow-rate of blood was 120 mL/min and the backpressure reached 0.093 MPa; The adsorption capacity of protein A of the column for IgG from human plasma has been measured. When plasma and blood individually circulated through the column for 1 h, the column with 139 mg protein A immobilized on the matrix (6 mg protein A/g dry matrix) adsorbed 553 mg IgG (23.8 mg IgG/g dry matrix) from human plasma and 499.4 mg IgG (21.5 mg IgG/g dry matrix) from human blood respectively. The circulation time had a great influence on IgG adsorption capacity; but the circulation rate had a little influence on IgG adsorption capacity. The result of extracoporeal blood perfusion for dog showed that the Protein A column has good blood biocompatibility.

Chromatography↗
PubMed1999

Testosterone inhibits apoptosis of Leishmania donovani-infected macrophages.

AIM: Investigate the effect of the male sex hormone, testosterone (Te), on apoptosis of bone marrow derived macrophages (BMMs) from female C57BL/6j mice METHODS: Propidium iodide (PI) staining and transmission electron microscopy (TEM) techniques were used to investigate apoptosis specific-morphological changes. BMMs derived from Te-treated mice and Oil-treated mice were challenged with Leishmania donovani (L. d.), Oligo-nucleosomal DNA were extracted 24 h post infection to detect apoptosis. RESULTS: The removal of M-CSF from the medium could induce BMM apoptofsis. And the DNA fragmentation assay also indicated that: 1. there was no difference in the amount of apoptotic cells between Te and Oil group; 2. Te + L. d. group had significantly less dead cells than Oil + L. d. group demonstrating that Te could prevent apoptosis of macrophage infected with L. d. to a greater extent. CONCLUSION: Te inhibits apoptosis of the macrophages infected with L. d., however, this inhibition did not occur in the macrophages uninfected with L. d. Te-induced macrophage apoptosis-inhibition may play an important role in Te-induced immunosuppression.

Animals↗
PubMed1999

[Determination of 2,4-dinitrochlorobenzene in environmental water by primary-secondary wavelengths new spectrophotometry].

In basic solution, dinitrochlorobenzene may react on pyridine to form a purplish red compound. In this paper with the absorption property of a suspended liquid against light a new analytical method as primary-secondary wavelengths spectrophotometry was studied to determine trace dinitrochlorobenzene in environmental water. In 0-50 microg dinitrochlorobenzene/25 mL, the calculation curve is very stable and hardly affected by environment conditions. Experiments for practical waters have shown that the detection limit was 0.7 microg/25 mL dinitrochlorobenzene and RSD < or = 2.7% and the recovery rate was 99.2%-101.0%.

Dinitrochlorobenzene↗
PubMed1999

[Vibration studies of amphetamine and methamphetamine by micro Raman].

For the first time, we obtained and investigated the Raman spectra of amphetamine and methamphetamine by micro Raman with incidence excitation light 514.5 nm under the ambient environment. According to the fact that both molecules belong to single substituted benzene which has the symmetry of Cy2v, the attribution of Raman vibration modes in amphetamine and methamphetamine molecules was carried out by studying the spectral lines in the two spectra. The Raman line that only appeared in methamphetamine but could not be seen in any other drugs we have investigated was most possibly attributed to the stretching vibration between C-N(+)-C.

Amphetamine↗
PubMed1999

[Studies of narcotics by micro Raman spectroscopy].

For the first time, the Raman spectra of eight kinds of narcotics were obtained and investigated by micro Raman. The results indicated that the Raman spectra were affected by the numbers and position of methyl in substituent groups. Under incidence light 514.5 nm and appropriate measurement condition, high quality Raman spectra of drugs with low fluorescence background were obtained. In addition, we discovered that narcotine and thedaine were very sensitive to strong light radiation. Finally, by comparing Raman spectra carefully for all drugs we measured the specific Raman peaks were given for the purpose of distinguishing different kinds of drugs.

Illicit Drugs↗
PubMed1998

Analysis of CAG/CTG repeat size in Chinese subjects with schizophrenia and bipolar affective disorder using the repeat expansion detection method.

BACKGROUND: Family studies of schizophrenia and bipolar affective disorder provide evidence for genetic anticipation, which (in common with a number of mendelian disorders), may be caused by triplet repeat expansion. This hypothesis is strengthened by evidence from repeat expansion detection (RED) analysis revealing association between the psychoses and long CAG/CTG trinucleotide repeats. METHODS: We performed RED on Han Chinese subjects with schizophrenia (82), bipolar affective disorder (43), and normal controls (61), using a CTG10 oligonucleotide. RESULTS: Comparison between cases and controls revealed no significant association between long repeats and affected status. We also found no detectable association with age at onset and repeat length in either bipolar affective disorder or schizophrenia. Overall, the size distribution of CAG/CTG repeats in Chinese subjects was not significantly different from those reported previously for Caucasian subjects. CONCLUSIONS: These findings indicate that CAG/CTG repeat expansion is not likely to be a major etiological factor for psychosis in Chinese populations.

Adolescent↗
PubMed1998

Measurement of photosystem I activity with photoreduction of recombinant flavodoxin.

Flavodoxin can function as an alternative electron acceptor for photosystem I (PSI) in place of ferredoxin under iron-limiting conditions. The isiB gene, encoding the flavodoxin in Synechococcus sp. PCC 7002, was overexpressed in Escherichia coli. Under the conditions employed, most recombinant flavodoxin (rFlvd) was in soluble form with cofactor correctly inserted. The absorption spectrum of rFlvd was identical to that of the native flavodoxin of the cyanobacteria. Photoreduction of rFlvd by PSI particles and thylakoid membranes was determined directly by monitoring the absorption change at 467 nm. The optimal conditions for rFlvd photoreduction were determined. Compared to other methods currently employed to measure PSI activity such as oxygen uptake in the presence of methyl viologen and NADP+ photoreduction in the presence of ferredoxin and ferredoxin:NADP+ oxidoreductase, measurement of PSI activity with flavodoxin as an electron acceptor has several advantages. It measures the full-chain electron transfer chain of PSI since flavodoxin accepts electrons from FA/FB and it is much simpler than the method with NADP+ photoreduction. With this method, we found that the affinity of wild-type PSI for rFlvd was 35% higher than that of the PsaE-less PSI, showing that this method is sensitive to structural changes of PSI. Our results demonstrate that rFlvd photoreduction is an effective and simple method for PSI activity measurement.

Bacterial Proteins↗
PubMed1998

Changes in serum melatonin levels in response to pinealectomy in the chicken and its correlation with development of scoliosis.

STUDY DESIGN: Normal, sham, and groups of chickens subjected to pinealectomy from which serum melatonin levels were measured and correlated with scoliosis development in a period of 5 weeks. OBJECTIVES: To measure serum melatonin levels in chickens subjected to pinealectomy and control chickens and correlate findings with development of scoliosis. SUMMARY OF BACKGROUND DATA: In a previous study by others, scoliosis developed in 100% of chickens subjected to pinealectomy, and serum melatonin levels were found to be reduced. Previous results in a study by the authors showed scoliosis developing in only approximately 55% of chickens that underwent pinealectomy. METHODS: Young chickens were subjected to pinealectomy. Control groups consisted of sham operation and normal groups. Radiographs and blood samples were taken at weekly intervals to monitor scoliosis development and measure serum melatonin levels using radioimmunoassay techniques. RESULTS: Scoliosis developed in only 52% of chickens that underwent pinealectomy, but all had low levels of serum melatonin and no circadian rhythm. The chickens in the two control groups maintained normal serum melatonin levels and rhythms. CONCLUSIONS: Pinealectomy in young chickens reduces serum melatonin levels and eliminates the melatonin circadian rhythm. It can also produce scoliosis, but low levels of serum melatonin are a poor predictor of development of scoliosis.

Animals↗
PubMed1998

Quaternary structures of a catalytic subunit-regulatory subunit dimeric complex and the holoenzyme of the cAMP-dependent protein kinase by neutron contrast variation.

Chimeric molecules of the cAMP-dependent protein kinase (PKA) holoenzyme (R2C2) and of a Delta1-91RC dimer were reconstituted using deuterated regulatory (R) and protiated catalytic (C) subunits. Small angle scattering with contrast variation has revealed the shapes and dispositions of R and C in the reconstituted complexes, leading to low resolution models for both forms. The crystal structures of C and a truncation mutant of R fit well within the molecular boundaries of the RC dimer model. The area of interaction between R and C is small, seemingly poised for dissociation upon a conformational transition within R induced by cAMP binding. Within the RC dimer, C has a "closed" conformation similar to that seen for C with a bound pseudosubstrate peptide. The model for the PKA holoenzyme has an extended dumbbell shape. The interconnecting bar is formed from the dimerization domains of the R subunits, arranged in an antiparallel configuration, while each lobe contains the cAMP-binding domains of one R interacting with one C. Our studies suggest that the PKA structure may be flexible via a hinge movement of each dumbbell lobe with respect to the dimerization domain. Sequence comparisons suggest that this hinge might be a property of the RII PKA isoforms.

Catalytic Domain↗
PubMed1998

Complex gangliosides are essential in spermatogenesis of mice: possible roles in the transport of testosterone.

Mice, homozygous for disrupted ganglioside GM2/GD2 synthase (EC 2.4. 1.94) gene and lacking all complex gangliosides, do not display any major neurologic abnormalities. Further examination of these mutant mice, however, revealed that the males were sterile and aspermatogenic. In the seminiferous tubules of the mutant mice, a number of multinuclear giant cells and vacuolated Sertoli cells were observed. The levels of testosterone in the serum of these mice were very low, although testosterone production equaled that produced in wild-type mice. Testosterone was found to be accumulated in interstitial Leydig cells, and intratesticularly injected testosterone was poorly drained in seminiferous fluid in the mutant mice. These results suggested that complex gangliosides are essential in the transport of testosterone to the seminiferous tubules and bloodstream from Leydig cells. Our results provide insights into roles of gangliosides in vivo.

Animals↗
PubMed1998

Chemokine receptor CCR5 functionally couples to inhibitory G proteins and undergoes desensitization.

Chemokine receptor CCR5 is not only essential for chemotaxis of leukocytes but also has been shown to be a key coreceptor for HIV-1 infection. In the present study, hemagglutinin epitope-tagged human CCR5 receptor was stably expressed in Chinese hamster ovary cells or transiently expressed in NG108-15 cells to investigate CCR5-mediated signaling events. The surface expression of CCR5 was confirmed by flow cytometry analysis. The CCR5 agonist RANTES stimulated [35S]GTPgammaS binding to the cell membranes and induced inhibition on adenylyl cyclase activity in cells expressing CCR5. The effects of RANTES were CCR5 dependent and could be blocked by pertussis toxin. Furthermore, overexpression of Gialpha2 strongly increased both RANTES-dependent G-protein activation and inhibition on adenylyl cyclase in cells cotransfected with CCR5. These data demonstrated directly that activation of CCR5 stimulated membrane-associated inhibitory G proteins and indicated that CCR5 could functionally couple to G-protein subtype Gialpha2. The abilities of CCR5 to activate G protein and to inhibit cellular cAMP accumulation were significantly diminished after a brief prechallenge with RANTES, showing rapid desensitization of the receptor-mediated responsiveness. Prolonged exposure of the cells to RANTES caused significant reduction of surface CCR5 as measured by flow cytometry, indicative of agonist-dependent receptor internalization. Our data thus demonstrated that CCR5 functionally couples to membrane-associated inhibitory G proteins and undergoes agonist-dependent desensitization and internalization.

Adenylate Cyclase Toxin↗
PubMed1998

The hrp23 protein in the balbiani ring pre-mRNP particles is released just before or at the binding of the particles to the nuclear pore complex.

Balbiani ring (BR) pre-mRNP particles reside in the nuclei of salivary glands of the dipteran Chironomus tentans and carry the message for giant-sized salivary proteins. In the present study, we identify and characterize a new protein component in the BR ribonucleoprotein (RNP) particles, designated hrp23. The protein with a molecular mass of 20 kD has a single RNA-binding domain and a glycine-arginine-serine-rich auxiliary domain. As shown by immunoelectron microscopy, the hrp23 protein is added to the BR transcript concomitant with transcription, is still present in the BR particles in the nucleoplasm, but is absent from the BR particles that are bound to the nuclear pore complex or are translocating through the central channel of the complex. Thus, hrp23 is released just before or at the binding of the particles to the nuclear pore complex. It is noted that hrp23 behaves differently from two other BR RNP proteins earlier studied: hrp36 and hrp45. These proteins both reach the nuclear pore complex, and hrp36 even accompanies the RNA into the cytoplasm. It is concluded that each BR RNA-binding protein seems to have a specific flow pattern, probably related to the particular role of the protein in gene expression.

Amino Acid Sequence↗
PubMed1998

The expression of constitutively active isotypes of protein kinase C to investigate preconditioning.

The role of protein kinase C (PKC) in ischemic preconditioning remains controversial because of difficulties with both its measurement and pharmacological manipulation. We investigated preconditioning in isolated neonatal rat cardiocytes by expressing constitutively active isotypes of PKC. Observations at differing durations of simulated ischemia suggested beta-galactosidase (beta-gal) activity reflected viability within transfected myocytes. Preconditioning with 90 min of ischemia significantly increased beta-gal activity and myocyte survival after 6 h of ischemia; an effect abolished by PKC inhibitors. After co-transfection with plasmids encoding beta-gal and either constitutively active mutants of PKC-delta, PKC-alpha, wild type PKC-delta, or empty vector, cardiocytes were subjected to 6 h of ischemia. Only PKC-delta, rendered constitutively active by a limited deletion within the pseudosubstrate domain, consistently increased resistance to simulated ischemia (beta-gal activity was 85.6 +/- 11.9% versus 53.7 +/- 6.5% (p </= 0.01) and dead myocytes 46.8 +/- 3.4% versus 68.7 +/- 2.8% (p </= 0.01)). Since transfection was apparent in only 5-12% of cells, the results suggested a protective bystander effect that was confirmed by co-culture of transfected myocytes with untransfected myocytes. In neonatal cardiocytes expression of active PKC-delta increases resistance to simulated ischemia. This observation may provide further insight into the mechanism and possible avenues for therapeutic exploitation of preconditioning.

Animals↗
PubMed1998

Comparison of the retention characteristics of aromatic and aliphatic reversed phases for HPLC using linear solvation energy relationships.

The similarities and differences in retention characteristics of aromatic and aliphatic phases have been elucidated by the use of linear solvation energy relationships (LSERs). Three aromatic phases and three aliphatic phases were investigated in a series of mobile phases. The results of LSERs on a polymer-based aromatic phase, poly(styrene-divinylbenzene) resin (PRP-1) are very different from those on either silica- or zirconia-based aromatic and aliphatic phases. Retention on all aromatic and aliphatic phases except PRP-1 is dominated by two factors: the solute size and hydrogen bond acceptor basicity. On the other hand, in addition to these two major contributions, retention on PRP-1 is markedly influenced by the solute hydrogen bond donor acidity. We believe that PRP-1 exhibits a more adsorption-like retention mechanism than do the other phases. With the inorganic oxide-based phases, the aromatic phases are less retentive than the aliphatic phases but show a larger dependence on molecular polarizability. The enhanced polarizability of aromatic phases is the likely cause of some differences in their chromatographic selectivity relative to the aliphatic phases.

Chemical Phenomena↗