Biomedical subjects

Hua Guo

Publications and source records attributed to Hua Guo.

65 records · Page 4Linked to original sources

PubMed2003

An improved gridding method for spiral MRI using nonuniform fast Fourier transform.

The algorithm of Liu and Nguyen [IEEE Microw. Guided Wave Lett. 8 (1) (1998) 18; SIAM J. Sci. Comput. 21 (1) (1999) 283] for nonuniform fast Fourier transform (NUFFT) has been extended to two dimensions to reconstruct images using spiral MRI. The new gridding method, called LS_NUFFT, minimizes the reconstruction approximation error in the Least Square sense by generated convolution kernels that fit for the spiral k-space trajectories. For analytical comparison, the LS_NUFFT has been fitted into a consistent framework with the conventional gridding methods using Kaiser-Bessel gridding and a recently proposed generalized FFT (GFFT) approach. Experimental comparison was made by assessing the performance of the LS_NUFFT with that of the standard direct summation method and the Kaiser-Bessel gridding method, using both digital phantom data and in vivo experimental data. Because of the explicitly optimized convolution kernel in LS_NUFFT, reconstruction results showed that the LS_NUFFT yields smaller reconstruction approximation error than the Kaiser-Bessel gridding method, but with the same computation complexity.

Algorithms↗

PubMed2003

Significance of changes of gastrointestinal peptides in blood and ileum of experimental spleen deficiency rats.

AIM: To explore the mechanism of spleen deficiency (SD) by studying the relationship of gastro-intestinal peptides level and ileal electro-mechanical activity of SD rats and cold restrain rats. METHODS: (1) spleen deficiency (SD) model was established by feeding Houpou:Zhishi: Dahuang in the ratio of 3:3:2, 3 ml/time, for 42 days. (2) The cold restrain stress model: Animals were restrained on grille and placed in a cool water at 18 degrees for 3 h. (3) Substance P (SP) and vasoactive intestinal peptide (VIP) levels in all layers of initial part of ileum and blood in rats were measured by radioimmunoassays (RIA) while changes of electric activity and motility in ileum of rats were recorded with electrode and strain gauge. RESULTS: SP levels in ileum and blood of experimental SD rats were significantly higher than that of the control groups (9.89+/-5.65 vs 1.22+/-1.18, P<0.005, in ileum; 22.7+/-3.95 vs 6.60+/-1.47, P<0.001, in blood) while the VIP levels of the SD rats were significantly lower than that of the controls (3.50+/-2.01 vs 9.10+/-4.91, P<0.05, in ileum; 229.8+/-62.4 vs 560.4+/-151.3, P<0.001, in blood). As compared with the controls, the average frequency of slow electric waves (21.3+/-0.96 vs 18.2+/-2.28, P<0.05) and motility (21.5+/-0.58 vs 18+/-2.65, P<0.005) of SD rats increased obviously and the frequency of fast waves of SD rat also increased. In spontaneous recovery cases, SP levels recovered significantly (compared with the SD groups, 2.99+/-0.62 vs 9.89+/-5.65, P<0.001, in ileum; 14.4+/-4.22 vs 22.7+/-3.95, P<0.001, in blood) but did not drop to normal. After the SD rats treated with Chinese herbs (Jiawei Sijun zi Tang), SP improved (compared with SD cases, 2.20+/-1.25 vs 9.89+/-5.65, (P<0.001), in ileum; 10.7+/-1.88 vs 22.7+/-3.95, (P<0.001), in blood) and VIP in blood also improved (compared with SD rats, 485.7+/-229.0 vs 229.8+/-62.4, P<0.01) while the amplitude of motility decreased apparently (compared with the SD rats, 0.64+/-0.096 vs 0.89+/-0.15, P<0.01). The ileal SP levels of cool stress didn't change while the ileal VIP levels of cool stress became significantly lower than that of the control groups (2.87+/-0.87 vs 9.10+/-4.91, P<0.01). The blood SP levels of cool stress were significantly higher (15.60+/-1.83 vs 6.60+/-1.47, P<0.001) whereas the blood VIP levels of cool stress were significantly lower than that of the control group (153.4+/-70.46 vs 560.4+/-151.30, P<0.001). CONCLUSION: Changes of SP and VIP levels in initial part of ileum and blood of SD rats and cool stress rats may be closely related to the gastrointestinal motility disorders presented in SD and cool stress rats. the Chinese herbs (Jiawei Sijun zi Tang) currently used have partially therapeutic effect.

Animals↗

PubMed2003

Application of modified two-cuff technique and multiglycosides tripterygium wilfordii in hamster-to-rat liver xenotransplant model.

AIM: To modify the hamster-to-rat liver xenotransplant technique to prevent postoperative complications, and to study the inhibiting effect of multiglycosides tripterygium wilfordii (T(II)) on immune rejection. METHODS: Female golden hamsters and inbred male Wistar rats were used as donors and recipients, respectively. One hundred and twelve orthotopic liver xenotransplants were performed by Kamada's cuff technique with modifications. Over 72 hour survival of the animal after operation was considered as a successful operation. When the established surgical model became stable, 30 of the latest 42 cases were divided into untreated control group (n=15) and T(II) group (n=15) at random. Survival of recipients was observed. Liver specimens were collected at 2 and 72 h from the operated animals and postmortem, respectively, for histological study. RESULTS: The successfully operative rate of the 30 operations was 80 %, and the survival of the control and T(II) group was 7.1+/-0.35 was days and 7.2+/-0.52 days, respectively (t=0.087,P=0.931). The rate of conjunctival hyperemia in control group (100 %) differed significantly from that (31 %) in T(II) group (P=0.001). Rejection did not occur in both groups within 2 h postoperatively, but became obvious in control group at 72 h after surgery and mild in T(II) group. Although rejections were obvious in both groups at death of recipients, it was less severe in T(II) group than in control group. CONCLUSION: This modified Kamada's technique can be used to establish a stable hamster-to-rat liver xenotransplant model. Monotherapy with multiglycosides tripteryguiumwilfordii (30 mg x kg(-1) x d(-1)) suppresses the rejection mildly, but fails to prolong survival of recipients.

Animals↗

PubMed2003

[An experimental study of inhibiting effect of decoy oligodeoxynucleotides on the gene expression of collagen in NIH3T3 cell].

OBJECTIVE: To investigate the effect of activator protein-1 (AP-1) decoy-oligodeoxynucleotides (Decoy-ODNs) on the expression of fibroblast alpha2 type I collagen, so as to explore the gene therapy of pathologic scar. METHODS: Decoy-ODNs targeting AP-1 were designed and synthesized. NIH3T3 cells were transfected by cationic liposomes. The distribution of Decoy-ODNs in the cells was investigated. The inhibiting effects of Decoy-ODNs on AP-1 were determined by electrophoretic mobility shift assay (EMSA). And the effects of Decoy-ODNs on the collagen synthesis in the cells were analyzed by RT-PCR. RESULTS: AP-1 Decoy-ODNs could competitively inhibit the AP-1 in vitro activity. Cationic liposomes could play roles by effectively transfecting Decoy-ODNs into the plasma and nucleus. The mRNA expression of fibroblast alpha2 type I collagen decreased evidently after 24 hours of Decoy-ODNs action. CONCLUSION: Decoy-ODNs could inhibit the mRNA expression of fibroblast alpha2 type I collagen by antagonizing AP-1.

Animals↗

PubMed2003

[Transdifferentiation of tubular epithelial cells in tubulointerstitial fibrosis].

OBJECTIVE: To observe the transdifferentiation of renal tubular epithelial cells in tubulointerstitial fibrosis. METHODS: The renal tubulointerstitial fibrosis model in Wistar rats was established by unilateral renal vein ligature. The rats were kept 25 days after renal vein ligature. The kidneys were dissected every 5 days by killing 5 rats. The morphological changes of the kidney were observed by light microscopy, electron microscopy, polarizing microscopy and immunohistochemistry method. RESULTS: The histological changes showed tubular atrophy and disappearance, widening of intertubular spaces with increased lymphocytes and mononuclear cells infiltration and fibrosis. The CK marker in injured and atrophic epithelial cells gradually weakened, but the alpha-SMA, vimentin, TGF-beta(1), collagen I and III showed gradually stronger positivity for immunohistochemistry. Some interstitial cells became positive for CK. Electron microscopy revealed decreased mitochondria, increased endoplasmic reticulum and microfilament of the tubular epithelial cells which merged into the interstitium. During the early stage of tubulointerstitial fibrosis, there was proliferation of type III collagen and then followed by type I collagen at later stage when observing the Sirius Red stained sections under the polarizing microscope. CONCLUSION: Tubular epithelial cells can transdifferentiate to fibroblasts during the process of tubulointerstitial fibrosis.

Actins↗

PubMed2003

[Relationship between tubulointerstitial fibrosis and mononuclear-macrophage].

OBJECTIVE: To study the relationship between monocyte/macrophage (MC/MP) accumulation and tubulointerstitial fibrosis. METHODS: The renal tubulointerstitial fibrosis model in Wistar rats was established by unilateral renal vein ligature. The rats were fed for 25 days. The kidneys were obtained every 5 days by killing the rats. The morphological changes of tubulointerstitial fibrosis were observed by light microscopy with HE, PAS, PASM and Masson staining. Immunohistochemistry and double immunohistochemistry were used to observe MC/MP accumulation and proliferation. In situ hybridization and immunochemistry were used to observe MCP-1 and M-CSF expression in experimental renal tissue. The MCP-1 protein expression was inspected by Western blot. All the data were analyzed statistically. RESULTS: The pathological changes of tubulointerstitial fibrosis were typical. There were many MC/MPs accumulsated in the interstitial space at the early stage and some of them were PCNA positive. At the late stage both accumulation and proliferation of MC/MPs were decreased. The portion of monocyte proliferation was high correlated with the MC/MP accumulation. In situ hybridization showed the positive signals of MCP-1 and M-CSF were mainly located in the cytoplasm of degenerated tubular epithelium and they were strong at the early stage, weak at the late stage. MCP-1 by immunochemistry and Western blot were consistent with in situ hybridization. The MC/MP accumulation was high correlated with the expression of MCP-1 and tubular epithelium degeneration. The portion of monocyte proliferation was high correlated with the expression of M-CSF. CONCLUSION: There was obvious accumulation of MC/MP at the early stage of tubulointerstitial fibrosis. The accumulation came from infiltration and proliferation which were regulated by degenerated tubular epithelial cells producing MCP-1 and M-CSF. MC/MP accumulation was highly correlated with tubular degeneration. MC/MP promoted tubulointerstitial fibrosis and damaged tubular epithelium by secreting a variety of cytokines.

Animals↗

PubMed2003

Effect of decoy-oligodeoxynucleotides on expression of inflammation mediators in pMPhi cells from rats.

OBJECTIVE: To study the effect of decoy-oligodeoxynucleotides (decoy-ODNs) in dumbbell shape with the oligodeoxynucleotide sequence similar to nuclear factor kappa B (NF-kappaB) cis-elements on expression of inflammation mediators in pMPhi cells from rats. METHODS: With carriers of cationic liposomes, decoy-ODNs were transfected into pMPhi cells of rats. Then the inhibiting effects of the decoy-ODNs on tumor necrosis factor alpha (TNFalpha), interleukin-6 (IL-6) and IL-10 were analyzed. RESULTS: Decoy-ODNs could decrease the expression of TNFalpha and IL-6 in dose-dependent fashion but had weaker inhibiting effect on IL-10. CONCLUSIONS: Decoy-ODNs targeting NF-kappaB can decrease the expression of inflammatory mediators in pMPhi cells from rats.

Animals↗

PubMed2003

[Effects of short-action hypnotics triazolam and zopiclone on simulated flight performance].

OBJECTIVE: To evaluate the effects of short-action hypnotics triazolam and zopiclone on simulated flight performance so as to provide experimental evidences for the use of these drugs in aircrew. METHOD: Six healthy young male volunteers served as the subjects. They were asked to take triazolam (0.25 mg), zopiclone (7.5 mg) or placebo at noon time (13:00) and sleep for 1 h. Simulated flight performances were tested in a simulator 1 h, 2 h, 3 h, 4 h, 6 b, 8 h, 10 h and 20 h (next morning 9:00) after taking the drugs. The experiments were done once a week for 3 weeks. RESULT: No significant difference was found between simulated flight performances before or after triazolam while simulated flight performances at 2 h and 3 h after taking zopiclone showed significant decrease (P<0.05), but restored to normal 4 h after taking the drug. CONCLUSION: Short-action hypnotics triazolam had no significant effect on simulated flight performance, while zopiclone had significant adverse effects on simulated flight performance at 2 h and 3 h after taking the drug.

Adolescent↗

PubMed2002

Quantum calculation of highly excited vibrational energy levels of CS2(X) on a new empirical potential energy surface and semiclassical analysis of 1:2 Fermi resonance.

We report a refined potential energy function for the ground electronic state of CS2 based on a least-squares fitting to several low-lying experimental vibrational frequencies. Energy levels up to 20,000 cm(-1) have been obtained on this empirical potential using the Lanczos algorithm and potential optimized discrete variable representation. Among them, 329 levels below 10,000 cm(-1) are assigned with approximate normal mode quantum numbers (n1, n(0)2, n3), based on expectation values of one-dimensional (1D) reference Hamiltonians. An effective Hamiltonian is extracted from these assigned levels. The agreement with experimental data, including those of several isotopically substituted species, is excellent. In addition, some Fermi and anharmonic resonances are analyzed. The nearest neighbor level spacing and delta3 distributions indicated that the vibrational spectrum of CS2 is largely regular in the energy range up to 20,000 cm(-1). Semiclassical phase space analysis, including bifurcation analysis of the spectroscopic Hamiltonian, is used to interpret subtle anomalies signaled by expectation values used in normal mode assignments. The meaning of Fermi resonance is clarified by contrasting the semiclassical analysis of CS2 and CO2.

Carbon Disulfide↗

PubMed2002

Effect of recombinant epidermal growth factor on ocular surface re-epithelization following amniotic membrane transplantation in patients with pterygium excision.

OBJECTIVE: To observe the effect of recombinant human epidermal growth factor (rhEGF) on ocular surface re-epithelization and the efficacy of amniotic membrane transplantation in patients with pterygium. METHODS: Amniotic membrane transplantation was performed on 40 eyes of 36 patients with pterygium after removal of pterygium. All the eyes were randomly divided into 2 groups: 20 eyes received rhEGF ophthalmic solution and the other 20 drug vehicle. The healing rates of the corneal and conjunctival epithelium were observed respectively. Follow-up study lasting for 3 to 12 months was conducted in all the cases postoperatively. RESULTS: The healing rate of both the corneal and conjunctival epithelium in rhEGF-treated group (74.983+/-18.998 micrometer/h and 36.584+/-7.888 micrometer/h respectively) was significantly faster than the control (59.372+/-17.197 +/-m/h and 29.18+/-5.450 micrometer/h respectively, P<0.01 for both comparisons). Follow-up witnessed no recurrence of the disease. CONCLUSIONS: rhEGF effectively promotes the healing of ocular surface epithelium defect, and amniotic membrane transplantation is a good surgical procedure for treating pterygium.

Adult↗

PubMed2002

Orthotopic liver transplantation in treatment of 77 patients with end-stage hepatic disease.

OBJECTIVE: To summarize the experience of human orthotopic liver transplantation (OLTx) in treatment of patients with end-stage hepatic disease and their perioperative management. METHODS: A retrospective analysis was made on OLTx performed in 77 patients from April 1993 to September 2001 in our department included combined liver-kidney transplantation (6 patients) and living related liver transplantation (2). Among them, 76 were adults and 1 was infant (67 males and 10 females). The donors included 75 non-heart beating donors and 2 living related donors. Veno-venous bypass was used only in 45 cases during the operation. immunosuppressive agents consisted of cyclosporine, cellcept, ALG corticosteroids and FK506. RESULTS: The one-year survival rates of grafts and recipients with benign hepatic disease were 75%. The recipients this year are surviving with good function of grafts. CONCLUSION: Liver transplantation is the best therapeutic method for a large number of patients with end-stage hepatic disease in China.

Adolescent↗