Biomedical subjects
Publications and source records attributed to C Lei.
We describe a neutron radiography technique that can be used to map the distribution of 3He impurities in liquid 4He, providing direct and quantitative access to underlying transport processes. Images reflecting finite normal- and superfluid-component 4He velocity fields are presented.
The time-dependent diffusion of 3Heatoms perpendicular to the axis of a single macroscopically large cylindrical pore is studied using a steady (or constant) gradient-recalled echo sequence. Measurements of the effective 3Hediffusion coefficient extending from the free-diffusion regime to the motionally averaged regime are presented, and are well-described by analytic solutions to the Bloch-Torrey equation based on the gaussian phase approximation. Our data yield the value 0.140(6)m2/s for the self diffusion coefficient of 3Heat a temperature of 296 K and a pressure of 1.00 Torr. Adaptations of these methods should enable the study of complex pore geometries as model systems.
We have developed a method for simultaneous recording of high-resolution topography and cell surface fluorescence in a single scan which we call scanning surface confocal microscopy. The resolution of the system allows imaging of individual fluorescent particles in the nanometer range on fixed or live cells. We used this technique to record the interaction of single virus-like particles with the cell surface and demonstrated that single particles sink into the membrane in invaginations reminiscent of caveolae or pinocytic vesicles. This method provides a technique for elucidating the interaction of individual viruses and other nanoparticles, such as gene therapy vectors, with target cells. Furthermore, this technique should find widespread application for studying the relationship of fluorescently tagged molecules with components of the cell plasma membrane.
OBJECTIVE: To observe the effect of attenuated varicella-zoster virus (VZV) on replication of HBV in vitro and vivo. METHODS: The attenuated VZV were inoculated into the ducks infected with DHBV and into the cultural HepG(2) 2.2.15 cells, respectively. DHBV DNA, HBsAg and HBeAg were detected from the duck serum and cell cultural fluid by dot-blot hybridization and EIA. RESULTS: The decline of DHBV DNA in duck serum was found in two dosage groups. Compared with pre-treatment, the level of AD value in 200 pfu/kg group was significantly decreased from 1.17+/-0.29 to 0.59+/-0.45 (10 day after VZV treatment) and 0.21+/-0.21 (5 day after withdrawal of VZV)(t =3.51, 7.54, P<0.001). The level in 400 pfu/kg group was from 0.70+/-0.25 to 0.32+/-0.17 on the 5th day of withdrawal of VZV (t =3.58, P<0.01), respectively after treatment. The inhibitory rates of HBeAg and HBsAg were 61% and 33%, respectively. The effect on HBeAg seems to be more obvious than on HBsAg. CONCLUSIONS: Attenuated VZV could significantly decrease serum DHBV DNA in DHBV-infected ducks and directly inhibit the HBeAg and HBsAg secreted by 2.2.15 cells, suggesting that VZV seems to interfere or inhibit the replication of DHBV.
We demonstrate a very fast heterogeneous redox reaction of substrate-free cytochrome P450(cam) on a glassy carbon electrode modified with sodium montmorillonite. The linear relationship of the peak current in the cyclic voltammogram with the scan rate indicates a reversible one-electron transfer surface process. The electron transfer rate is in the range from 5 to 152 s(-1) with scan rates from 0.4 to 12 V/s, respectively. These values are comparable to rates reported for the natural electron transfer from putidaredoxin to P450(cam). The formal potential of adsorbed P450(cam) is -139 mV (vs NHE) and therefore positively shifted by 164 mV compared to the potential of substrate-free P450(cam) in solution. UV-VIS and FTIR spectra do not indicate an influence of the clay colloidal particles on the heme and the secondary structure of P450(cam) in solution. However, P450(cam) adsorbed on the surface of the clay-modified electrode may undergo partial dehydration resulting in the shift of the formal potential.
OBJECTIVE: To study the changes and significance of oblique occipital frontal diameter (OFD) and superior inferior diameter (SID) of the hepatic left lobulus in different stages of hepatic fibrosis, and to evaluate the value of corresponding serological examination in the non-invasive diagnosis to hepatic fibrosis and cirrhosis. METHODS: Seventy-two patients with chronic hepatitis were confirmed by biopsy. OFD and SID of the hepatic left lobulus were measured by type B ultrasonic flaw detector. Serum levels of hyaluronic acid (HA), laminin (LN), type IV collagen (CIV) and type III procollagen (PCIII) were measured by radioimmunoassay. RESULTS: SID of the hepatic left lobulus in S(4) stage was 5.7cmA1.5cm, significantly shorter than the values of 7.7cmA1.4 cm in S(0) stage. OFD of the hepatic left lobulus was longer in S(4) stage than S(0) stage, but the difference didn't reach statistical significance. Serum levels of HA, LN,CIV, and PCIII elevated as the increase of fibrosis. HA and PCIII increased to 273.4mug/LA131.3mug/L and 167. 4mug/LA48.1mug/L in S3 stage from 66.2mug/LA35.0mug/L and 103. 4mug/LA23.8mug/L in S(0) stage. CONCLUSION: Changes in of SID and OFD of the hepatic left lobulus and serum levels of HA and PCIII may indicate indirectly mid-late hepatic fibrosis or early cirrhosis.
OBJECTIVE: To study the pathological features of liver biopsy from long-term blood donors with chronic hepatitis C. METHODS: From 250 long-term blood donors with positive serum anti-HCV antibody for more than five years, 66 donors with abnormal ALT level were selected and enrolled in this study. Liver biopsy was performed on these cases and the specimens stained with HE, and reticulin. Modified Schemer's classification for grading and staging was used during pathological observation. Twenty biopsies with serum HCV-RNA levels higher than 5.0 Meq/ml (bDNA) were studied immunohistochemically (SABC) for NS5. RESULTS: All cases displayed mild pathological changes. Grade 1 (G(1)) inflammation was 4.8% (3/63), G(2) 63.5% (40/63), G(3) 28.6%(18/63), G(4) two case. Stage 1 (S(1)) fibrosis was 60.3% (38/63), S(2) 34.9% (22/63), S(3) 3.2% (2/63), S(4) only one case. The main lesion was periportal inflammation, such as bile duct damage (100.0%), dense lymphoid aggregates (82.5%) and piecemeal necrosis (89.5%). Intralobular injury of hepatocytes was rather mild. Bridging necrosis and steatosis were not common and observed in only 12.3% (8/66) and 9.2% (6/66) respectively. As for fibrosis, proliferation and deposition of collagen were mainly distributed in the portal and perisinusoidal areas. Among 20 specimens with serum HCV-RNA levels higher than 5.0 Meq/ml (bDNA), all bile duct epithelial cells were positive for HCV-NS5 antigen, while hepatocytes in 4 cases were negative. CONCLUSION: (1) The pathological changes in this series show overall similarity with that of patients with posttransfusion hepatitis C. The main damages are portal and periportal inflammation, such as lymphoid aggregates, bile duct damage, piecemeal necrosis, and extensive periportal and perisinusoidal fibrosis. Intralobular damage was mild with occasional steatosis, which may be related to malnutrition, low level of serum iron due to long term donation. (2) Epithelial cells of the bile duct may be of another site for virus replication, thus it is related with bile duct damage and periportal inflammation.
The present study was designed to detect the change of substance P (SP) in firearm wounds and its relationship with wound healing. Twenty two rabbits were randomly divided into two groups, one with firearm wounds created by steel balls shooting rabbits' thighs and another with stab wounds created by knife. The experimental design did not include direct injury to femora major peripheral nerve trunks or blood vessels. SP content in wound tissue of both groups was measured with radioimmunoassay (RIA). Histologic examination was performed on the wound and the saphenous and sciatic nerves away from the wound-track edges. It was found that both types of injuries caused an increase of SP content in the wound compared with normal tissue. At three to 10 days after injury, SP content was lower in firearm wounds than that in stab wounds. Pathomorphologic observation showed the indirect injuries to the saphenous and sciatic nerves in the rabbits with firearm wounds were more severe than those with stab wounds. Meanwhile, wound healing in the firearm wounds was poor compared with that in the stab wounds. The results suggest that the change in SP in firearm wounds differs from that in cold weapon wounds as a result of the presence of indirect injuries to major peripheral nerve trunks created by laceration shock wave and cavity effects, and SP in vivo may participate in wound healing as a growth factor. Therefore, the improvement of neuropeptide metabolism in firearm wound may be an important measure for accelerating wound healing.
To investigate whether the expression of angiotensinogen (ANG) in rat kidney proximal tubules is stimulated by dexamethasone and isoproterenol, immortalized rat proximal tubular cells (IRPTC) were cultured in a monolayer. Immunoreactive rat ANG (IR-rANG) in the culture medium was measured by a specific radioimmunoassay (RIA) for rANG. This RIA was developed by employing rabbit antiserum against the purified recombinant rat ANG (rANG). The purified rANG from plasma and the iodinated rANG were used as the hormone standard and tracer, respectively. The RIA is specific for rat ANG and it has no cross-reactivity with other pituitary hormone preparations or other rat plasma proteins. The sensitivity of detection of the RIA is approximately 2 ng of rANG. The levels of IR-rANG in the culture media of IRPTC ranged from 2 to 5 ng/ml/24 hr/10(6) cells. The addition of dexamethasone (10(-13) to 10(-5) M) stimulated the expression and secretion of rANG from IRPTC in a dose-dependent manner, whereas the addition of isoproterenol alone had no effect. However, a combination of both dexamethasone and isoproterenol synergistically stimulated the expression and secretion of rANG by IRPTC. The synergistic effect of dexamethasone and isoproterenol was blocked by the presence of RU 486 (a glucocorticoid receptor antagonist) or propranolol (beta-adrenoceptor blocker). These studies suggest that the addition of dexamethasone and isoproterenol acts synergistically to stimulate the expression and secretion of ANG protein in rat proximal tubules in vivo.
A new approach to construct a second-generation amperometric biosensor is described. The classical dye methylene green as a probing-needle mediator and horseradish peroxidase as a base enzyme were coimmobilized in the same montmorillonite-modified bovine serum albumin (BSA)-glutaraldehyde matrix to construct a H2O2 sensor. The immobilization matrix was formed from the pretreated sodium montmorillonite colloid in which the enzyme and the cross-linker were dissolved. Immobilization of methylene green from the dye mother solution was attributed to the adsorption function of the montmorillonite, whereas immobilization of horseradish peroxidase was attributed to the cross-linking function of the BSA-glutaraldehyde as usual. Cyclic voltammetry and potentiostatic measurements indicated that methylene green efficiently mediated electrons from the base electrode to the enzyme in the matrix. The sensor responded rapidly to low H2O2 concentration and achieved 95% of the steady-state current in less than 20 s, with a detection limit of 4.0 x 10(-7) M H2O2.
A case of pancreatoblastoma arising in a five year old girl was analysed using histochemical and immunohistochemical methods. The tumour was composed of tubular gland-like structures, squamoid components and some small round cells surrounding tubular structures. The cytoplasm of the small round cells and a few of the squamoid cells was positive on staining with Grimelius argyrophil stain. Immunohistochemically, tumour tissue was positive for neurone specific enolase. The cytoplasm of some of the small round cells was positive for insulin, glucagon, somatostatin, pancreatin polypeptide, thyroid stimulating hormone, follicle stimulating hormone, and neurotensin. These results suggest that this tumour arose from primitive multipotential stem cells, showing exocrine and neuroendocrine differentiation.
According to the result of nationwide human parasitic disease distribution survey, the public significance of parasitosis control was set forth in terms of preventive health care and economic impact as well as parasitosis control and primary health care. A suggestion was made on the control strategy aiming at the parasitosis of priorities listed in the above survey.
Four experiments were conducted to study 1) factors affecting porcine oocyte maturation in culture medium and 2) a new method for oocyte maturation outside the porcine body. In Experiment 1, five groups of oocytes were cultured in m-TCM199 or m-KRB medium for 24 to 28, 32 to 36 or 40 to 42 hours and then were fertilized in vitro. The cleavage rate (two to four-cell stage) of oocytes cultured for 32 to 36 hours was significantly higher than those of the other oocytes. The results indicate that a suitable culture period for the in vitro maturation of porcine oocytes is 32 to 36 hours. In Experiment 2, four groups of oocytes were cultured in m-KRB or m-KRB supplemented with PFF, PMSG or FSH for in vitro maturation, and the cleavage rates of oocytes were 7.94, 22.56, 30.23 and 23.26%, respectively, after in vitro fertilization. The results show that porcine follicular fluid (PFF) and gonadotrophins added to the culture medium promote porcine oocyte maturation in vitro. In Experiment 3, oocytes were cultured in m-KRB or m-TCM199, supplemented with both gonadotrophin and pocine folliclar fluid for maturation in vitro. After fertilization in vitro, the cleavage rates of oocytes were 26.32 and 27.93% for the two media. The results indicate that the difference between m-KRB and m-TCM199 was insignificant when the media were used to culture porcine oocytes. But there was a significant difference when PFF and gonadotrophins were added to the basic media. In Experiment 4, porcine oocytes were transferred into the reproductive tracts of other animals for maturation. After 34 to 36 hours, the oocytes were collected and fertilized in vitro. The cleavage rates of oocytes were 10.42, 28.45, 3.33 and 36.36%, respectively, for the oocytes matured in mouse uterine horns, rat uterine horns, rat oviducts or rabbit oviducts. The results show that porcine oocytes can be matured in the reproductive tracts of other animals.
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Fifty men underwent testicular biopsy at the time of varicocele ligation. The biopsies were scored and also a portion from each biopsy was subjected to meiotic analysis. All men were followed up (mean follow-up 19.3 months). There were no consistent histologic or meiotic abnormalities, and there was no evidence that the varicocele side was more defective than the contralateral side. Thirteen pregnancies were recorded, and these occurred only when the mean Johnsen score from one or other testis was greater than 6.0.
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