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Biomedical subjects

Y Zhou

Publications and source records attributed to Y Zhou.

At least 829 records · Page 46Linked to original sources
PubMed1994

Equilibrium dialysis of metal-serum albumin. I. Successive stability constants of Zn(II)-serum albumin and the Zn(2+)-induced cross-linking self-association.

The binding of Zn(II) to human serum albumin (HSA) and bovine serum albumin (BSA) was intensively studied by equilibrium dialysis. The successive stability constants were obtained by least-squares fitting. For both the Zn(II)-HSA and Zn(II)-BSA systems, the successive stability constants are basically similar, though such constants for the latter generally slightly larger than those for the former; the order of magnitude of K1 and K2 was found to be approximately 10(5) M-1. The twelve binding sites found for Zn(II)-HSA and fourteen binding sites for Zn(II)-BSA can be divided into three and two different sets, respectively, but in both systems, there exist approximately three identical strongest binding sites. The binding equilibrium of Zn(II)-HSA markedly depends on the concentration of HSA. The type of Scatchard plots indicates the existence of the Zn(2+)-induced cross-linking self-association of HSA, which was found from Wyman plots to be the strongest at a concentration of Zn2+ in the range (4-6) x 10(-6) M. The maximum of the apparent self-association constants k2 so obtained was approximately 2.6 x 10(4) M-1. Such a self-association mechanism and the order of magnitude of K1 and K2 both to some extent support the inference that the zinc group ions are bound to the cysteinyl sulphur atoms.

Animals↗
PubMed1994

Cycloartane triterpene glycosides from the hairy root cultures of Astragalus membranaceus.

Agroastragaloside II, a new astragaloside was isolated from the hairy root culture of Astragalus membranaceus. Its structure was established as 3-O-beta-(2'-O-acetyl)-D-xylopyranosyl-6-O-beta-D-glucopyranosyl-(24S)- 3 beta,6 alpha,16 beta,24,25-pentahydroxy-9,19-cyclolanostane on the basis of spectroscopic data. Three known astragalosides, astragaloside II, isoastragaloside I and 3-O-beta-D-xylopyranosyl-cycloastragenol were also isolated.

Astragalus propinquus↗
PubMed1994

Imaging indoor tracer-gas concentrations with computed tomography: experimental results with a remote sensing FTIR system.

This work demonstrates for the first time the feasibility of computed tomography (CT) reconstructions of pollutant concentrations in a real room setting. A remote sensing Fourier transform infrared spectrometer was mounted on a moving base in a controlled ventilation chamber. A passive tracer was released from a point source into the room under constant ventilation conditions. A series of experiments gathered multiple path-averaged measurements in a two-dimensional plane for CT reconstruction. Simultaneous readings were gathered with a multiple-point sampling array for later comparison to the CT reconstructed concentrations. Good qualitative agreement between the reconstruction and point sample data was obtained. Limitations encountered due to the temporal resolution, size, and geometry of the experimental apparatus are clearly surmountable with better instrumentation.

Air Pollutants, Occupational↗
PubMed1994

Integrin switching regulates normal trophoblast invasion.

Cells invade extracellular matrices in a regulated manner at specific times and places during normal development. A dramatic example is trophoblast invasion of the uterine wall. Previous studies have shown that differentiation of trophoblasts to an invasive phenotype is accompanied by temporally and spatially regulated switching of their integrin repertoire. In the first trimester human placenta, alpha 6 integrins are restricted to cytotrophoblast (CTB) stem cells and downregulated in invasive CTBs, whereas alpha 5 beta 1 and alpha 1 beta 1 integrins are upregulated in differentiating and invasive CTBs. The goal of the present study was to determine whether these changes have functional consequences for CTB invasiveness. Using an in vitro invasion model, we determined first that aggregates of invading first trimester CTBs in vitro undergo the same pattern of integrin switching as was observed in situ, thereby validating the utility of the model. We then showed that antibody perturbation of interactions involving laminin or collagen type IV and their integrin alpha 1/beta 1 receptor inhibited invasion by CTBs, whereas perturbing interactions between fibronectin and the alpha 5/beta 1 fibronectin receptor accelerated invasion. Finally, we report that later gestation CTBs, which display greatly decreased invasive capacity, are also unable to upregulate alpha 1 beta 1 complexes, providing further evidence that this integrin is critical for CTB invasion. This gestational regulation is transcriptional. These data indicate that integrin switching observed during differentiation in situ has significant functional consequences for CTB invasion. The data suggest further that differentiating CTBs upregulate counterbalancing invasion-accelerating and invasion-restraining adhesion mechanisms. We propose that this contributes to regulating the depth of CTB invasion during normal implantation.

Blotting, Northern↗
PubMed1994

Effects of DX-9386, a traditional Chinese preparation, on passive and active avoidance performances in mice.

The acute effects of DX-9386, a traditional Chinese medicinal preparation (ginseng, polygala, acorus and hoelen), were studied on learning and memory performances in passive and active avoidance tests in normal, as well as in learning-impaired, mice. A single oral administration of the prescription had no effect on memory registration, consolidation or retrieval or on motor activity in normal mice. DX-9386 reduced the ethanol-induced impairment of memory registration in the step-down test and also tended to ameliorate the scopolamine-induced memory registration deficit in the same test. The preparation reduced the number of spontaneous responses in the active avoidance test. The preparation also prolonged the disappearance of righting reflex induced by pentobarbital. These results suggest that DX-9386 ameliorates the impairment effect of ethanol on learning and memory processes and also exhibits a sedative effect.

Administration, Oral↗
PubMed1994

Ameliorative effects of chronic treatment using DX-9386, a traditional Chinese prescription, on learning performance and lipid peroxide content in senescence accelerated mouse.

DX-9386 is a traditional Chinese prescription consisting of ginseng, polygala, acorus and hoelen. The effect of chronic oral treatment with this preparation on learning behaviors and lipid peroxide concentration was studied in senescence accelerated mouse (SAM). SAM P8, a senescence prone of SAM, and SAM R1, a senescence resistant substrain of SAM, were started on a diet containing 1% of DX-9386 from the age of 2 months. All the experiments were performed at the age of 10 months. The prescription ameliorated the memory disorders of SAM P8, as evaluated in a step down test as well as a spatial memory test. The preparation, however, did not affect the learning behaviors in SAM R1. DX-9386 reduced the elevated levels of lipid peroxide in the serum and liver of SAM P8, while it did not alter that in SAM R1. These results suggested that DX-9386 slowed the aging process of SAM P8 in terms of learning behaviors and lipid peroxidation.

Administration, Oral↗
PubMed1994

Beneficial effects of DX-9386, a traditional Chinese prescription, on memory disorder produced by lesioning the amygdala in mice.

The amygdala is one of the key areas of the brain involved in learning and memory. Bilateral lesions of the amygdala in 9-week-old mice induced impairment of memory acquisition and retention. DX-9386, a traditional Chinese medicinal prescription consisting of ginseng, polygala, acorus and hoelen, was orally administered to the lesioned mice after the operation until all the experiments were completed. From 15d after surgery, learning behavior in the step-down test was observed daily for 10 d. DX-9386 treatment ameliorated the memory acquisition deficit. The number of step-down events in the first testing trial was significantly decreased by administration of 250 mg/kg of the prescription to the lesioned group of mice. Choline acetyltransferase activity in the cerebral cortex of the lesioned mice was significantly decreased, while repeated administration of the prescription did not affect this biochemical parameter. These results indicate that the memory acquisition enhancing effect of DX-9386 may not be achieved by direct activation of cholinergic transmission in the brain but by some other mechanism(s).

Amygdala↗
PubMed1994

Major retinal cell components recognized by onchocerciasis sera are associated with the cell surface and nucleoli.

PURPOSE: Cellular localization of the components recognized by onchocerciasis autoantibodies has not been investigated in any detail in cultured retinal cells. This study sought to examine, in cultured retinal cells, the subcellular localization of major components that cross-react with onchocerciasis sera. METHODS: Immunofluorescence confocal laser scanning microscopy and Western blot analysis were carried out on adult pig retinal cells. RESULTS: The onchocerciasis sera contain antibodies cross-reacting strongly with components of the surface and nucleoli in both the cultured retinal pigment epithelial and neural retinal cells. These epitopes are not recognized by the control sera obtained from noninfected individuals residing in an onchocerciasis hyperendemic area, and from those with or without ocular disease who have never been in any of the onchocerciasis hyperendemic countries. Double-labeling immunofluorescence microscopy does not detect any colocalization of a putative onchocerciasis autoantigen, calreticulin, and those cellular components recognized by onchocerciasis sera in either cell type. Furthermore, none of the onchocerciasis sera tested recognized recombinant calreticulin by Western blot analysis. CONCLUSIONS: Major epitopes for onchocerciasis anti-retinal autoantibodies are associated with the surface and nucleolus components of retinal cells. Interaction of the onchocerciasis antibodies with the retinal cell surface molecules may play an important role in the development of ocular diseases initiated by the damage of retinal cells. Furthermore, the finding that the cellular components recognized by onchocerciasis sera do not colocalize with calreticulin, taken together with the observation of lack of recognition of recombinant calreticulin by these sera on Western blots, suggests that calreticulin is not a major onchocerciasis autoantigen.

Animals↗
PubMed1994

Functional expression of a mouse growth hormone receptor cDNA in transfected mouse L cells.

A cDNA encoding a full-length mouse (m) growth hormone receptor (GHR) derived from 3T3 F442A cells was amplified by RT-PCR and cloned into a mammalian expression vector. A mouse L cell line (mGHR1.6), which expresses high levels of full-length mGHR, was established. A mGHR-specific mRNA of approx 2.8 kb was found in these cells. Ligand binding studies showed that mGHR 1.6 cells were capable of binding 125I-hGH with a dissociation constant (Kd) of 2.9 +/- 0.13 nM. Scatchard analysis indicated that mGHR1.6 cells had only a single class of mGHR and possessed approx 128,000 GH specific binding sites per cell. Affinity crosslinking studies showed that the recombinant mGHR possessed an apparent molecular mass of 105 kDa. In addition, mGHR1.6 cells responded to growth hormones (GHs) from several species. Two proteins, pp92 and pp95, were found to be tyrosyl phosphorylated following GH treatment. An hGH antagonist, hGH-G120R, inhibited GH-induced phosphorylation of both pp92 and pp95 in a dose-dependent manner. This cell line may be used as an in vitro model in the studies of GH signal transduction and in the screening of GH analogs for biological activity.

3T3 Cells↗
PubMed1994

[Laser Doppler flowmetry for evaluation of nasal mucosa microcirculation].

The purpose of this study was to determine the blood flow within the human nasal mucose and whether it is changed in patients with chronic rhinitis. Using a laser Doppler flowmeter (He-Ne Laser equipment PF2 type), we measured the nasal mucosa blood flow (NMBF) in a group of healthy young subjects 108 (18-25 years) and three types of chronic rhinitis 89 (chronic rhinitis 15, allergic rhinitis 44, atrophic rhinitis 30). A Laser Doppler probe was placed on six different points of the nasal mucose membrane. The study data indicate that the average index of the NMBF of human are retentive steady and decreased obviously in three types chronic rhinitis. So it may be concluded that detection of NMBF is a useful method for evaluation of the therapy effect of chronic rhinitis.

Adolescent↗
PubMed1994

[Clinical and experimental study on effect of Chinese herbal drugs on producing prostaglandin in gastric mucosa].

The PG content were determined in 62 cases with peptic ulcer and erosive gastritis before and after the treatment of Chinese herbal drugs. The value of PGE2,PGF1 alpha, 6-keto-PGF1 alpha and TXB2 were 96.25 +/- 28.51, 14.24 +/- 13.26, 10.72 +/- 9.14 and 16.51 +/- 12.24 pg/mg respectively before the treatment and were 121.42 +/- 30.02, 18.59 +/- 18.40, 18.79 +/- 12.61, 8.29 +/- 6.27 pg/mg respectively after the treatment. 6-keto-PGF1 alpha was significantly increased (P < 0.01), TXB2 was decreased (P < 0.01), but there were no significant changes in PGE2 and PGF1 alpha. Experimental study also showed that Chinese Herbal drugs played an important role in protecting indomethacine induced ulcer rats.

6-Ketoprostaglandin F1 alpha↗
PubMed1994

Comparative observation on effect of electric acupuncture of neiguan (P 6) at chen time versus xu time on left ventricular function in patients with coronary heart disease.

Paired experimental design was adopted in this experiment for comparative observation on effect of electric acupuncture (EA) of Neiguan (P 6) at Chen Time (7 a.m. to 9 a.m.) versus Xu Time (7 p.m. to 9 p.m.) on left ventricular function in patients with coronary heart disease (CHD). The results show that EA performed at Chen Time could improve the left ventricular function of CHD patients as indicated by shortening of PEPI and decrease of PEPI/LVETI ratio; on the contrary, EA performed at Xu Time prolonged PEPI and raised PEPI/LVETI ratio in CHD patients, suggesting impairment of left ventricular function.

Acupuncture Points↗
PubMed1994

[The study of metaphasic chromosome pellicle].

Among 12 antichromosome antisera from scleroderma patients, four were found to be the antisera against the pellicle of metaphase chromosomes. Western blotting with these sera were achieved on the protein bands resolved by SDS-PAGE of the whole cell lysate and nuclear lysate of the ascites cells. The result showed 11 bands of the nuclear lysate reacted with antisera. Moreover, additional 8 were obtained in the whole cell lysate.

Animals↗
PubMed1994

An exon encoding the mouse growth hormone binding protein (mGHBP) carboxy terminus is located between exon 7 and 8 of the mouse growth hormone receptor gene.

A C57 black/6 mouse genomic library was screened for mGHR/BP using a mGHR cDNA hybridization probe. Two clones (mGHR-GA and mGHR-GB) were isolated. mGHR-GA contained an insert of 16 kb and hybridized only to exon 4 whereas mGHR-GB possessed an insert of 20 kb and hybridized to exons 6-10 of the mGHR cDNA. Oligonucleotide sequencing analysis confirmed that the mGHR-GA contained exon 4 and that the mGHR-GB possessed mGHR/BP genomic sequences from intron V through the 3' region of mGHR. In addition, mGHR-GB also contained a region, designated exon 8A, encoding the carboxy terminus of mGHBP. This exon is located between exons 7 and 8 of mGHR/BP gene. Two poly(A) additional signal sequences were found 54 bp downstream of the stop codon of mGHBP. Additionally, introns between exons 3/4 and 4/5 are > 12 and > 3 kb, respectively. Also, introns between exons 5/6, 6/7, 7/8A, 8A/8 (3' region of mGHBP), 8/9, 9/10, and the 3' region of mGHR are approx > 3 kb, 4 kb, 287 bp, 1569 bp, 6 kb, 265 bp, and > 3 kb, respectively. This study supports the hypothesis that mGHBP is generated by alternative splicing of a common primary mGHR transcript. It also demonstrates differences and similarities between mGHR/BP and hGHR genes.

Animals↗
PubMed1994

Caffeine as a probe for CYP1A2 activity: potential influence of renal factors on urinary phenotypic trait measurements.

Two established caffeine-based urinary methods for measuring CYP1A2 activity were compared with each other, and also with the systemic clearance of caffeine which served as a standard of reference for such activity. Following a standardized dose, caffeine (137X) and its metabolites were measured in urine and plasma of 39 healthy subjects. The measurements allowed determinations of: (1) systemic caffeine clearance (CL(caff)); (2) the caffeine metabolite ratio (AFMU + 1X + 1U)/17U determined in an overnight-urine specimen and referred to as CMR, and (3) the ratio (17X + 17U)/137X measured in urine collected between 4 and 5 h after caffeine intake and referred to as PCUR for 'paraxanthine-caffeine urinary ratio'. The PCUR showed a bimodal distribution and a relatively wide variation, CL(caff) and CMR were both normally distributed. The correlation between CL(caff) and CMR was r = 0.77 (p < 0.001), between CLcaff and PCUR r = 0.46 (p < 0.01), and between CMR and PCUR r = 0.40 (p < 0.02). The difference between the correlation coefficients 0.77 and 0.46 was statistically significant (z-test; p < 0.05). The well established decrease of caffeine metabolism by oral contraceptive use was observed with both CL(caff) and CMR but not with PCUR. Examination of possible explanations for the differences between PCUR and CMR led to the finding of a correlation between PCUR and the renal clearance of caffeine (CLr) with r = -0.47 (p < 0.01). Further scrutiny demonstrated that a bimodal or non-normal frequency distribution as shown by PCUR was also shown by CLr and by urine flow rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Receptive field properties of cat retinal ganglion cells during short-term IOP elevation.

PURPOSE: To examine and compare receptive field properties of cat retinal ganglion cells before and during intraocular pressure (IOP) elevation. METHODS: Responses of cat retinal ganglion cells to two sets of specially designed light or dark spots and annuli were recorded extracellularly. Receptive field properties were studied comparatively before and during short-term constant IOP elevation induced by keeping the retinal perfusion pressure at a critical level of about 30 mm Hg. RESULTS: All the responses, including properties of different types of receptive fields and different components of the cells' receptive fields, decreased during short-term IOP elevation. The responses of off-center cells were more tolerant of IOP elevation than those of on-center cells, whereas the responses of Y cells were less sensitive to IOP elevation than those of X cells. The responses of the centers of the receptive fields exhibited pronounced resistance to IOP elevation than those of the surround. The peak responses of the post-stimulus time histogram of all cells declined less than the mean responses during IOP elevation. CONCLUSIONS: The varied effects of short-term IOP elevation on different types (X and Y, on-center and off-center) of retinal ganglion cells and their receptive field properties may reflect the different degrees of ischemic effects on the retinal pathways that project to the different types of ganglion cells.

Action Potentials↗