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Biomedical subjects

Z H Lin

Publications and source records attributed to Z H Lin.

At least 19 recordsLinked to original sources
PubMed2003

The effects of simulated microgravity on cultured chicken embryonic chondrocytes.

Using the cultured chicken embryonic chondrocytes as a model, the effects of simulated microgravity on the microtubular system of the cellular skeleton, extracellular matrix, alkaline phosphatase activity, intracellular free calcium concentration and mitochondrial ATP synthase activity with its oligomycin inhibition rate were studied with a clinostat. The microtubular content was measured by a flow cytometer. The decrease of microtubular content showed the impairment of the cellular skeleton system. Observation on the extracellular matrix by the scanning electron microscopy showed that it decreased significantly after rotating, and the fibers in the extracellular matrix were more tiny and disorderly than that of the control group. It can be concluded that the simulated microgravity can affect the secreting and assembly of the extracellular matrix. In contrast to the control, there was a time course decrease in alkaline phosphatase activity of chondrocytes, a marker of matrix mineralization. Meanwhile a significant drop in the intracellular calcium concentration happened at the beginning of rotation. These results indicate that simulated microgravity can suppress matrix calcification of cultured chondrocytes, and intracellular free calcium may be involved in the regulation of matrix calcification as the second signal transmitter. No significant changes happened in the mitochondrial ATP synthase activity and its oligomycin inhibition rate. Perhaps the energy metabolism wasn't affected by the simulated microgravity. The possible mechanisms about them were discussed.

Alkaline Phosphatase↗
PubMed2003

Evidence of the production of silver nanoparticles via pretreatment of Phoma sp.3.2883 with silver nitrate.

AIMS: The objective was to demonstrate the size of silver particles produced by the filamentous fungus Phoma sp.3.2883 via adsorption and accumulation, and to confirm that this silver was in a reduced state. METHODS AND RESULTS: Mycelium was freeze-dried and then shake-cultured in a silver nitrate solution. It was found that up to 13.4 mg of silver was produced per gram of dry mycelium via atomic absorption spectrometer (AAS) analysis. The silver particles adsorbed on the mycelium were observed and measured under transmission electron microscope and their estimated size was 71.06 +/- 3.46 nm. Further examination of the particles via X-ray photoelectron spectroscope confirmed that the adsorbed silver particle had been reduced. CONCLUSION: The frozen mycelium of Phoma sp3.2883 has the potential for use in silver nanoparticle production. SIGNIFICANCE AND IMPACT OF THE STUDY: Silver nanoparticles could be used in the oil industry as an important catalyst and in the field of human medicine as a bactericide. The fungus Phoma sp3.2883 is a potential biosorbent that could be used for the production of these silver nanoparticles, and may also be useful in waste detoxification and in silver recovery programmes.

Adsorption↗
PubMed2001

[Quantitative structure-retention relationship (QSRR) studies of polychlorinated dibenzofurans (PCDFs) on diverse gas chromatographic stationary phases on a set of novel molecular distance edge vector].

By taking phenyl as a pseudo atom, there are three types of atom in the polychlorinated dibenzofuran (PCDF) molecule, being chlorine atom, oxygen atom and pseudo atom. The chemical structure of PCDF congeners is depicted by a novel molecular distance-edge vector(VMDE, mu in short), developed in our laboratory, which consists of the modified VMDE parameters based on the identical group as a pseudo atom instead of a traditional atom. Furthermore quantitative structure-retention relationships (QSRR) between the new mu vector and gas chromatographic (GC) retention behavior of PCDFs are generated by multiple linear regression method for various stationary phases. Four models, each of which is constructed by using all sample sets, with high correlation coefficient, r > 0.98, are developed for three columns (DB-5, SE-54, OV-101). In order to test the equation stability and prediction ability of each model, it is essential to perform a cross validation (CV) procedure. Satisfactory CV results have been obtained by using one external predicted sample every time with high correlation coefficients, r > 0.97. These results show that the new mu vector has high structural selectivity and good property relativity, and it is easy to calculate the mu vector. And the QSRR models have high relative coefficients, good stability and good predictability.

Air Pollutants, Occupational↗
PubMed2000

Safety and effectiveness of percutaneous fluoroscopic gastrostomy in cancer patients.

PURPOSE: To evaluate the safety and effectiveness of percutaneous fluoroscopic gastrostomy (PFG) in cancer patients. METHODS: We retrospectively analyzed the success rate, complication rate, and patient outcomes of PFG performed during a 15-month period in our hospital. The Cope type 10-French and 12-French self-retaining catheters were used for gastrostomy. RESULTS: Of the 113 PFG procedures requested during the study period, 112 (99.1%) were performed successfully; one procedure was cancelled because the nasogastric tube could not be passed through the obstructed esophagus. Thirty-day follow-ups were obtained for 92.0% of the procedures. Of the patients with at least 30 days of follow-up, eight (7.8%) died, but only two deaths (1.9%) were procedure-related. Major complications, including peritonitis and severe wound infection, occurred after eight procedures (7.8%). Minor complications, including superficial wound infection, tube fracture, leakage, severe pain, mild hemorrhage, and tube migration, occurred after 23 procedures (22.3%). The severity of pneumoperitoneum was significantly associated with the frequency of complications (p < 0.05). After placement of the gastrostomy, 68% of the patients maintained or increased their initial body weight; 28% lost 10% or less of their body weight; and 4% lost more than 10% of their body weight. CONCLUSIONS: PFG appears to be effective and relatively safe for long-term nutritional support in cancer patients.

Adult↗
PubMed1999

The effects of economic reform on health insurance and the financial burden for urban workers in China.

Since 1980, Chinese enterprises have been undergoing reforms in employment practice, taxation, and workers' health/welfare benefits coverage. In particular, Chinese businesses have been facing a major challenge with respect to the financial burden of providing medical benefits to their workers. The purpose of this paper is to analyse the impact of enterprise reform on workers' health care benefits and their financial burden due to medical expenses. This study is based on a 1992 survey conducted in 22 cities, and included 406 enterprises and 5920 workers. It was found that there were wide variations of coverage for health care benefits among urban Chinese workers. It was also found that workers with partial coverage were as likely to incur out-of-pocket medical expenditures as workers without coverage. These out-of-pocket medical expenditures could reach as high as 25% of a worker's annual income. Policy recommendations are discussed at the end of the paper.

Adult↗
PubMed1999

Effects of fluvastatin on structure and function of resistant vessels in spontaneously hypertensive rats.

AIM: To evaluate the effects of fluvastatin, a hydroxymethylglutaryl-CoA (HMG-CoA) reductase inhibitor, on the alterations of structure and function of resistant vessels in spontaneously hypertensive rats (SHR). METHODS: Eight-week-old male SHR were given fluvastatin 20 mg.kg-1.d-1 by gavage. Rats were decapitated at 16 wk. Wall-to-lumen area ratios (W/L) of thoracic aorta and mesenteric arteries (3rd grade branch) were assessed by morphometric assay. The effects of fluvastatin on vascular reactivity to sodium nitroprusside (SNP) and norepinephrine (NE), were studied with rings of thoracic aorta and mesenteric arteries isolated from rats. RESULTS: After 8 wk of treatment, histological examination showed that the wall-to-lumen area ratio was lower in SHRflu than that in SHR (0.44 +/- 0.09 vs 0.79 +/- 0.09, P < 0.05). EC50 of vasodilation response was much lower in SHRflu than that in SHR [(4.9 vs 190) pmol.L-1, P < 0.05], while EC50 of mesenteric artery rings from SHRflu was somewhat lower than that of SHR [(0.02 vs 0.04) nmol.L-1, P > 0.05]. In both aortic and mesenteric artery rings, EC50 of vasoconstriction in response to NE from SHRflu was higher than that of SHR [thoracic aorta: (0.20 vs 0.02) nmol.L-1, P < 0.05; mesentric arteries: (1.46 vs 0.72) nmol.L-1, P < 0.05]. CONCLUSION: Short-term treatment with fluvastatin ameliorated the vasomotoricity of resistant vessels, enhanced the sensitivity to vasodilator and depressed the sensitivity to vasoconstrictor; fluvastatin also attenuated the resistant vascular hypertrophy during the development of hypertension in SHR.

Animals↗
PubMed1998

A SINE species from hippopotamus and its distribution among animal species.

Thirty sequences of a short interspersed repetitive element (SINE) were isolated from genomic DNA of Hippopotamus amphibius (hippopotamus). RNA polymerase III split promoter sequence was observed in all of the 30 sequences; and poly(A)-like structure at 3'-end, as well as direct repeat flanking to the repetitive sequence in many of the 30 sequences. A comparison of the consensus sequence of the 30 sequences with sequences in a DNA database (DDBJ/GENBANK/EMBL) revealed 93% homology to the consensus sequence of a whale SINE, CHR-2, and 73% homology to mouse glutamic acid tRNA. Phylogenetic analysis of tRNA-related regions of the sequences with all of the mouse tRNAs revealed that glutamic acid tRNA was genetically closest to the hippopotamus SINE. In addition, the tRNA-related region of the consensus sequence was folded into a cloverleaf structure as with mouse glutamic acid tRNA. These findings led us to conclude that the SINE of hippopotamus was genetically related to a whale SINE, CHR-2 [the hippopotamus SINE was named CHR-2(hippo)] and was a retroposon derived from glutamic acid tRNA. Hipo53 and hipo95, which were the genetically most separated CHR-2(hippo) sequences in the present study, were used as a probe for dot-blot hybridization to examine the distribution of their homologous sequences among animal species. Although the distribution spectra of hipo53 and hipo95 homologous sequences in animal species differed to some extent, large amounts of both sequences were found in Hippopotamus amphibius and Globicephala macrorhynchus (whale); and small amounts in most of the animal species in Artiodactyla examined. These findings indicated that the hippopotamus and whale had more recently branched off from the clade that includes chevrotain and pecorans than the other animal species in the clade. The 30 CHR-2(hippo) sequences were aligned, and the substitution rates among the sequences were calculated with a different substitution rate model for transition and for transversion. The calculation combined with the mutation rate of the pseudogenes (r = 4.6 x 10(9)) indicated that CHR-2(hippo) sequences diversified at least 132 million years ago (Myr).

Animals↗
PubMed1996

Purification and crystal growth of F1-ATPase from pig heart mitochondria.

A method has been evolved toward the aim of getting suitable crystals for high resolution of structural analysis of F1-ATPase by X-ray crystallography. The different conditions for crystal growth of ATPase that were isolated and purified by different methods from pig heart mitochondrial ATP synthase had been compared and screened. A simple method for purification of F1-ATPase was adopted. The F1-ATPase is released with chloroform from submitochondrial particles. Then it was treated with fractional precipitation of (NH4)2SO4 and finally was further purified by employing the sephadex G 200 column. The crystals of F1-ATPase were usually obtained after a few months. They appeared to have uniform morphology of tetrahedron. They diffracted to a resolution of 7A. The diffraction data were collected on the XRD-100 Siemens Area Detector. According to a total of 240 frames, the cell parameters obtained are a = b = 147 A, c = 208 A, alpha = beta = gamma = 90 alpha, the probable space group is P4 or its antipode. The reproducibility of this method for crystallization of F1-ATPase is good.

Animals↗
PubMed1995

Piezoelectric immunosensor for the detection of immunoglobulin M.

A piezoelectric immunosensor has been developed for the determination of human IgM. The crystals are AT-cut and have a basic resonant frequency of 9 MHz. Immobilization of goat antihuman IgM antibodies to the crystals' surfaces was accomplished via a CNBr-activated copolymer coating of 2-hydroxyethyl methacrylate and methylmethacrylate. The IgM piezoelectric immunosensor can be used for the human IgM determination in the range 5-93 micrograms ml-1. The analytical results given by this approach were in satisfactory agreement with those given by the single radical immunodiffusion procedure. The sensitivity, specificity and reproducibility of this immunosensor were investigated. Further, the valent value of goat antihuman IgM antibody binding with human IgM antigen and the affinity constant of immunoreaction in this experimental system were studied. After washing with tetrahydrofuran, a crystal can be re-used 20 times without detectable loss of sensitivity.

Biosensing Techniques↗
PubMed1995

[Elimination effect of ethyl alcohol on the DCCD-induced inhibition of hydrolytic activity of H+-ATPase complex].

12.5% ethyl alcohol was added into the reaction system containing mitochondrial H(+)-ATPase complex of pig heart, which was preincubated with 0.5 microgram/ml DCCD dicyclohexylcarbodiimide) at 30 degrees C. Or the DCCD and ethyl alcohol were simultaneously incubated with H(+)-ATPase at 30 degrees C. In either case, the inhibition of the hydrolytic activity of H(+)-ATPase caused by DCCD could be completely eliminated in the presence of ethyl alcohol. If methyl alcohol was instead of ethyl alcohol, the DCCD inhibition could only be partly eliminated. In the replacement of ethyl alcohol by dimethyl sulfoxide, no elimination could be observed. After preincubation of 2 micrograms/ml oligomycin with H(+)-ATPase complex instead of DCCD, the same concentration of ethyl alcohol could not caused elimination effect, which indicates no un-coupling effect happened by ethyl alcohol. The kinetic experimental result showed that ethyl alcohol exhibits non-competitive inhibition to the hydrolytic activity of H(+)-ATPase complex. It was deduced that ethyl alcohol could result in conformational change of F1 of the complex, such as to affect the activity of the enzyme. The measurement of DPH (diphenylhexatriene) fluorescence polarization, the fluorescence labelled with N-(1-pyrenyl) maleimide and intrinsic fluorescence of H(+)-ATPase complex compared with control show that the three cases, i.e. only treated with DCCD, only treated with ethyl alcohol or treated with DCCD and ethyl alcohol, appear different conformations of H(+)-ATPase complex. But the conformation caused by DCCD and ethyl alcohol was more like that by ethyl alcohol. This is consistent with results obtained from activity of DCCD plus ethyl alcohol and only ethyl alcohol. These results mentioned above indicate that the mechanism of ethyl alcohol eliminating the DCCD-induced inhibition of H(+)-ATPase is a conformational interaction caused by DCCD and ethyl alcohol.

Animals↗
PubMed1994

Product-activation of Escherichia coli membrane-bound H(+)-ATPase (F1F0-ATPase) connected with epsilon-subunit at alkaline pH.

Mutant strain AN1518 or AN2387 (Gly48-->Asp in epsilon-subunit) and partial revertant strain AN2540 (Gly48-->Asp, Pro47-->Ser in epsilon-subunit) of E. coli were used in a kinetic study of membrane-bound H(+)-ATPase. It was found that at pH 9.0 mutant strain AN1518 or AN2387 and partial revertant strain AN2540 gave a low initial rate, which increased with time until linearity was reached after 1-2 min. This phenomenon was prominent in mutant strains, but was not so obvious in wild-type AN346 of E. coli; this property is similar to F1-ATPase reported by Cox [1]. The mechanism of the slow activation of membrane-bound H(+)-ATPase was further investigated in this paper. The experimental results indicated that the hydrolytic rate of E. coli F1F0-ATPase that increased with time was membrane protein concentration- and pH-dependent, and that the product ADP produced during ATP hydrolysis is the factor causing the slow activation. Preincubation of the hydrolytic product ADP with a concentration comparable to that produced in the assay (20 microM) caused initial activation of ATP hydrolysis and abolished the slow activation. On the other hand, with the removal of ADP during the progress of the hydrolytic reaction it could be seen that the slow activation was abolished as well. In order to test the relationship between the epsilon-subunit and ADP involved in the slow activation, trypsin treatment was carried out on the membrane-bound H(+)-ATPase of various strains. The activation observed after trypsin treatment was on the order of AN1518 > AN2540 > AN346. The activation effects of ADP and trypsin were not found to be additive. This implies that ADP acted in a similar way to trypsin, i.e., to cause removal of the epsilon-subunit. A tentative mechanism of the slow activation was proposed that ADP, a product of ATP hydrolysis, could induce conformational changes of F1F0 at alkaline pH 9.0, thus weakening the binding strength between the epsilon-subunit and other subunits of F1F0, and resulting in removal or partial removal of the epsilon-subunit. This further impaired the coupling of F1 and F0 in the mutant strains; as a consequence the rate of ATP hydrolysis was increased.

Adenosine Diphosphate↗
PubMed1994

Indomethacin inhibition of hog gastric H+/K(+)-ATPase arises from its effect on both the enzyme protein and the lipid bilayer.

Indomethacin showed a dose-, time-, and pH-dependent, noncompetitive inhibitory effect on hog gastric H+/K(+)-ATPase. Four percent of total indomethacin in the buffer (0.20 mmol/liter) bound to the H+/K(+)-ATPase vesicles (15 micrograms/ml). It markedly quenched the intrinsic fluorescence of the enzyme, and decreased the membrane fluidity. Thus, the inhibitor effect of indomethacin may arise from both a direct effect on the hydrolytic and H+ transport functions of the enzyme and a disturbing effect on the lipid bilayer of the vesicle.

Adenosine Triphosphatases↗
PubMed1994

[Effect of indomethacin on H+ transportation of pig gastric H+/K(+)-ATPase].

As a noncompetitive inhibitor of pig gastric H+/K(+)-ATPase, indomethacin inhibited the H+ transportation function of the enzyme, leading to not only the obvious dissipation of H+/K(+)-ATPase-generated H+ gradients, but also the decreasing of the H+ gradient formation ability of the enzyme. 4% of indomethacin was able to penetrate into the lipid bilayer of H+/K(+)-ATPase vesicles at 0.15 mg/ml protein concentration, which showed an influence of indomethacin to the membrane. Indomethacin reduced the membrane fluidity of H+/K(+)-ATPase vesicles significantly. It also damaged the conformation of membrane protein extraordinarily, which was evidenced by decreasing the intrinsic fluorescence of H+/K(+)-ATPase. From the results, we suggest that the effect of indomethacin on H+/K(+)-ATPase is taken place by its inhibition on H+/K(+)-ATPase protein, as well as by its influence on the membrane lipid bilayer of H+/K(+)-ATPase vesicles.

Animals↗
PubMed1992

The chelating-resin modified electrode and its application in the detection of copper in human samples.

A new kind of carbon paste electrodes modified by chelating resin was prepared for detection of trace amount of copper in human hair. As the ion exchange between chelating resin and cupric ions and the coordination reaction on the modified electrode take place at the same time, this method has high sensitivity and good selectivity. The detection limit is 6 x 10(-9) mol/L. The average percentage of recovered copper is 108 +/- 8.3% and the variant coefficient (CV) 7.7%.

Cation Exchange Resins↗
PubMed1991

Anti-tumor effects of recombinant human macrophage colony-stimulating factor, alone or in combination with local irradiation, in mice inoculated with Lewis lung carcinoma cells.

Recombinant human (rhu) macrophage colony-stimulating factor (M-CSF) was evaluated for efficacy, either alone or in combination with local X-irradiation (LR), in mice inoculated subcutaneously (s.c.) with Lewis lung carcinoma (LLC) cells. The size of the primary tumor and numbers of lung metastases, 21 days after tumor inoculation and 15 days after the start of treatment, were reduced by 87% in tumor-bearing mice treated with 20 micrograms/dose M-CSF s.c. twice a day for 5 days. LR (800 cGy) to the tumor once a week for 2 weeks had a moderate anti-tumor effect and enhanced the anti-tumor effect of M-CSF. Hematological parameters, including nucleated cellularity in peripheral blood, femoral marrow, spleen and peritoneal exudate, as well as marrow and splenic granulocyte-macrophage progenitor cells, and numbers of splenic Thy 1.2+ cell and peritoneal mast cells, were perturbed in LLC-bearing mice, and were influenced by treatment with M-CSF and LR. Treatment with M-CSF plus LR, but not with either agent alone, was associated with a significant, although slight, enhancement in survival time for LLC-bearing mice. Inability to obtain a better survival-enhancing effect appeared to be related to the limited treatment, since the anti-tumor effects of M-CSF were more notable early on in disease progression and were related to the dose of M-CSF used. The effects of M-CSF were most probably indirect ones on the host immune system. M-CSF, in combination with LR, may be of benefit in the treatment of human tumors that have metastatic potential.

Animals↗