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Biomedical subjects

C Feng

Publications and source records attributed to C Feng.

At least 37 records · Page 2Linked to original sources
PubMed1999

[Determination of sexual hormones in cosmetics by using Re-HPLC method].

A Re-HPLC method for the determination of seven kinds of sexual hormones, such as estriol in cosmetics was established. Zorbax C18 and Methanol-water were used as solid phase and liquid phase respectively. Methanol was used to extract the hormones in samples using a ultrasonic method. In the background with cosmetic samples, the relative standard deviations of those seven kinds of added sexual hormones were 1.2%-4.4% at low concentration and 2.1%-5.8% at high concentration. The recoveries rates of those hormones were 87.7%-103.1% and 86.6%-104.4%, respectively.

Chromatography, High Pressure Liquid↗
PubMed1999

Altered outward K(+) currents in Drosophila larval neurons of memory mutants rutabaga and amnesiac.

K(+) currents in cultured Drosophila larval neurons have been classified into four categories according to their inactivation time constants, relative amplitude, and response to K(+) channel blockers 4-AP and tetraethylammonium. The percentage (65%) of neurons displaying K(+) currents which were reduced to 30% in amplitude by 5 mM cyclic adenosine monophosphate (cAMP) analog 8-bromo-cAMP in both Drosophila memory mutants rutabaga (rut) and amnesiac (amn) was significantly larger than that (50%) in wild type. This initial characterization provides evidence for altered K(+) currents in both rut and amn mutants. Arachidonic acid, a specifical inhibitor of Kv4 family (shal) K(+) channels, was found to inhibit K(+) currents in cultured Drosophila neurons, suggesting the presence of shal channels in these neurons.

4-Aminopyridine↗
PubMed1999

Dietary omega-3 polyunsaturated fatty acids from fish oil reduce interleukin-12 and interferon-gamma production in mice.

The objective of this study was to investigate the impact of feeding mice a diet rich in n-3 polyunsaturated fatty acids (PUFA) from fish oil on the interleukin-12 (IL-12) and interferon-gamma (IFNgamma) production during the early stage of an infectious challenge with Listeria monocytogenes. Weanling female C3H/HeN mice were fed AIN-93G experimental diets containing 20%, by weight one of three fat sources: lard (low PUFA), soybean oil (n-6 PUFA) or a mixture (9:1) of menhaden fish oil and corn oil (n-3 PUFA). After 4 weeks, mice were injected intraperitoneally with 10(5) Listeria monocytogenes and the concentration of IL-12(p70) and IFNgamma in serum was determined 24 h post-infection by ELISA. IL-12p35, IL-12p40 mRNA, and IFNgamma mRNA in the spleen were quantified by RNase protection assay. The number of IFNgamma-producing cells in the spleen was determined by flow cytometry using an intracellular staining procedure. We found that n-3 PUFA-fed mice had lower levels of circulating IL-12 at 24 h post-infection than n-6 PUFA- or low PUFA-fed mice (9.7+/-3.4 pg/ml vs. 61.6+/-10.6, and 44.4+/-12.5 pg/ml, respectively; P=0.002, n = 10/trt). The level of IL-12 p35 mRNA did not significantly differ among dietary treatment groups. However, IL-12p40 mRNA was significantly lower in n-3 PUFA- and n-6 PUFA-fed mice compared to low-PUFA-fed mice. Further, the n-3 PUFA group also had the lowest circulating IFNgamma (4.4+/-1.8 ng/ml vs. 9.1+/-1.0, and 9.7+/-2.1 ng/ml, respectively; P = 0.007. n = 8-10/trt). The n-3 PUFA-fed mice had significantly lower IFNgamma mRNA in their spleens compared to the mice fed the other fat sources. In agreement with having lower circulating IFNgamma and lower splenic IFNgamma mRNA, n-3 PUFA-fed mice had a significantly lower percentage of IFNgamma-producing cells in their spleens compared with the n-6 PUFA-fed group (2.1+/-0.6 vs. 4.2+/-0.7%; P = 0.037, n = 10/trt). In summary, feeding mice a diet rich in n-3 PUFA from fish oil significantly lowered the production of both IL-12 and IFNgamma during the early phase of a Listeria infection.

Animals↗
PubMed1999

Responses to propofol in the pulmonary vascular bed of the rat.

BACKGROUND: Although a great deal is known about responses to propofol, controversy remains about its mechanism of action. The present study was undertaken to investigate the direct effects of 2,6-diisopropyl phenol, disodium edetate, and its intralipid emulsion in the rat pulmonary vascular bed and to better understand the mechanisms involved in propofol-mediated responses. METHODS: The effects of N omega-l-nitro-l-arginine benzyl ester (L-NABE), an inhibitor of nitric oxide synthase, of the cyclooxygenase blocker, meclofenamate, and the K + ATP channel antagonist, U-37883A, an ATP-sensitive potassium channel antagonist, on responses to propofol, acetylcholine, nitroglycerin, and isoproterenol were investigated in the isolated blood-perfused rat lung under low tone and high steady-state tone. RESULTS: Propofol produced a dose-dependent decrease in pulmonary arterial perfusion pressure. L-NABE significantly reduced vasodilator responses to acetylcholine, whereas the nitric oxide synthase inhibitor had no significant effect on responses to propofol. Meclofenamate significantly reduced vasodilator responses to arachidonic acid without effecting responses to propofol. Responses to propofol were not significantly changed in the presence of U-37883A, whereas U-37883A reduced vasodilator responses to levcromakalim. Additionally, 2,6-diisopropylphenol in a pure preparation as well as an intralipid preparation similar to propofol emulsion had no significant effect while disodium edetate had a dose-dependent depressor effect under high steady-state tone. CONCLUSION: Propofol has significant vasodilator activity in the pulmonary vascular bed of the rat but responses to propofol are not mediated or modulated by the release of nitric oxide, opening of K + ATP channels, or the release of vasodilator cyclooxygenase products.

Acetylcholine↗
PubMed1999

Dietary omega-3 polyunsaturated fatty acids reduce IFN-gamma receptor expression in mice.

Enrichment of immune cells in vivo or in vitro with omega-3 polyunsaturated fatty acid (n-3 PUFA) has been reported to diminish their response to interferon-y (IFN-gamma). We hypothesized that the n-3 PUFA-induced hyporesponsiveness to IFN-gamma is mediated, in part, by a reduction in the number of IFN-gamma receptors (IFNGR) expressed on the surface of these cells. To test this hypothesis, we fed mice experimental diets containing low or high amounts of n-3 PUFA. Thioglycollate-elicited peritoneal macrophages (PEC) were collected and tested for binding and internalization of [125I]-labeled recombinant murine IFN-gamma. High n-3 PUFA intake was associated with a significant (n = 2, p < 0.01) reduction in [125I]-IFN-gamma binding without affecting binding affinity (Kd). When studies were performed at 37 degrees C, high n-3 PUFA intake reduced internalization of [125I]-rmIFN-gamma by 20%-30% (n = 2,p < 0.001). Results from flow cytometric analysis of IFNGR-1 expression on the surface of murine splenocytes were in agreement with the binding studies. Further, total cellular IFNGR-1 from PEC and splenocytes was examined via immunoprecipitation and Western blotting. High n-3 PUFA diet was associated with a 50% decline (n = 3-6, p < 0.05) in total IFNGR-1 in both immune cell populations studied. These data suggest that reduced IFNGR expression may be responsible for immune cell hyporesponsiveness to IFN-gamma, which may, in part, explain some of the immunomodulatory and anti-inflammatory effects associated with the consumption of diets high in n-3 PUFA.

Animals↗
PubMed1999

An alternate pathway for type 1 T cell differentiation.

IFN-regulatory factor-1 (IRF-1) gene-disrupted mice are defective in IL-12 and IL-18 gene expression at the transcriptional and post-translational level respectively. The mutant mouse mounts a type 2 T cell response upon bacterial infection because of the impaired induction of the IL-12 p40 gene and IFN-gamma-producing type 1 T cells are not induced. We showed here, however, that different pathogens activate a novel pathway for inducing IFN-gamma-producing type 1 T cells even in an IRF-1-deficient mouse. This pathway is independent of IL-12 and IL-18, and is mediated by a distinct function of macrophage lineage cells. Macrophages of the mutant mice fail to activate the IL-12-dependent pathway, but they function in the IL-12-independent pathway in Plasmodium-infected mice. This leads to the hypothesis that the IL-12-independent novel pathway for inducing IFN-gamma-producing T cells is distinct from the classical type 1/type 2 T cell subset differentiation pathway.

Animals↗
PubMed1999

Altered immune response of interferon regulatory factor 1-deficient mice against Plasmodium berghei blood-stage malaria infection.

Nitric oxide (NO) is a short-lived biological mediator which can be induced in various cell types and is able to cause many metabolic changes in target cells. Inhibition of tumor cell growth and antimicrobial activity has been attributed to the stimulation of NO production by transcriptional upregulation of inducible nitric oxide synthase. In the present study, we used mice devoid of functional interferon regulatory factor 1 by targeted gene disruption (IRF-1(-/-)) to investigate the role of NO in the host immune response against blood-stage Plasmodium berghei ANKA infection. IRF-1(-/-) mice survived longer with a later onset of and a lower peak parasitemia despite the inability to produce appreciable levels of NO. The administration of exogenous interleukin-12 (IL-12) was able to prolong survival in the wild-type mice with an upregulation in the expression of both gamma interferon (IFN-gamma) and NO. However, the administration of IL-12 did not improve the survival of IRF-1(-/-) mice. These studies indicate that while IL-12 is able to mediate protection via an IFN-gamma- and NO-dependent pathway in the wild-type mice, such a protective mechanism may not be functional in the IRF-1(-/-) mice. Our results suggest that NO may not be essential for host immunity to the parasite and that IRF-1(-/-) mice are able to induce an IFN-gamma- and NO-independent mechanism against P. berghei infection.

Animals↗
PubMed1999

[Apoptosis of peripheral blood lymphocytes of patients with chronic hepatitis B and clinical significance].

OBJECTIVE: To explore the effects of apoptosis of peripheral blood lymphocytes (PBLs) of patients with chronic hepatitis B (CHB) on the persistent infection of hepatitis B virus (HBV). METHODS: The PBLs of 15 patients with CHB were isolated and cultured with or without Staphylococcus aureus enterotoxin B (SEB; 0.2 mg/L), or in the presence or absence of recombinant HBcAg (rHBcAg; 1.0 mg/L) for 48 hours in vitro. After incubations, the cells were harvested by centrifugation and then apoptosis of the PBLs was studied by staining with fluorescent dyes YOPRO-1 and Hoechst33342. RESULTS: The percentage of apoptotic cells of PBLs of patients with CHB was significantly higher than in normal controls (P < 0.01) in the presence or absence of SEB or rHBcAg, but the ratio of apoptotic cells in rHBcAg-stimulated PBLs of the patients was the highest, reaching (24.6 +/- 6.1)%. The patients with seropositive for HBeAg had higher percentage of apoptotic cells in their cultured PBLs than those with seronegative for HBeAg had, but the ratio of apoptotic cells in cultured PBLs of the patients with chronic heavy and severe hepatitis B was lower than that of the patients with chronic mild and moderate hepatitis B (P < 0.01). CONCLUSION: Activation-induced cell death of PBLs of the patients with CHB may be related to persistent infection of HBV, and assay of apoptosis of PBLs of patients with CHB may provide valuable information about pathogenesis of CHB.

Adolescent↗
PubMed1999

[Interleukin 10(IL-10) levels in serums and in culture supernatants of peripheral blood mononuclear cells from patients with chronic hepatitis B].

OBJECTIVE: To understand the impacts of interleukin 10(IL-10) in serums and in culture supernatants of peripheral blood mononuclear cells (PBMCs) from patients with chronic hepatitis B (CHB) on the persistent infection of hepatitis B virus (HBV). METHODS: The levels of IL-10 in serums and in culture supernatants of PBMCs from 15 patients with CHB and 6 normal controls were measured by ELISA method. PBMCs were cultured with or without Staphylococcus aureus enterotoxin B(SEB; 0.2 microgram/ml) or recombinant HBcAg(rHBcAg; 1.0 microgram/ml) for 48 hours in vitro. RESULTS: The levels of IL-10 in serums was greater in patients with CHB (123.11 +/- 13.89 ng/L) than in controls (95.97 +/- 11.68 ng/L, P < 0.01). Spontaneous, SEB-induced and rHBcAg-induced IL-10 production by PBMCs after culturing in vitro for 48 hours was also higher in patients with CHB (280.82 +/- 50.56 ng/L, 321.69 +/- 37.04 ng/L and 369.58 +/- 30.52 ng/L) than in controls (100.2 +/- 8.54 ng/L, 203.41 +/- 12.02 ng/L and 202.38 +/- 15.79 ng/L; P < 0.01). In addition, IL-10 production by rHBcAg-stimulated PBMCs was significantly greater than by SEB-stimulated PBMCs in patients with CHB. Patients with seropositive for HBV DNA had higher levels of IL-10 in serums and in culture supernatants of PBMCs than patients with seronegative for HBV DNA. But the levels of IL-10 were lower in patients with chronic heavy and severe hepatitis B than in patients with chronic mild and moderate hepatitis B. CONCLUSION: IL-10 may have an important role in persistent infection of HBV in patient with CHB.

Adolescent↗
PubMed1999

[A brief history of discovery of Helicobacter pylori].

The theoretical background for the diagnosis and treatment of upper digestive ulcer, gastritis and stomach carcinema was challenged by H. pylori, a microbe seems only under the microscope. This paper makes a brief review on the brief history of discovery and recent conclusion on the microbe, and explores its challenge to the traditional conception.

Digestive System Diseases↗
PubMed1999

Comparative frequency of bone sarcomas among different racial groups.

OBJECTIVE: To analyse comparatively the relevant data from bone tumor registries in China, Japan, and the United States. METHODS: The data of 38,959 histologically confirmed primary bone tumors collected by the Chinese Bone Tumor Registry 1957-1988, 20,272 collected by the Japanese Bone Tumor Registry 1972-1990, and 11087 diagnosed and treated at Mayo Clinic, USA were used for comparative analysis by race, age, sex and skeletal distribution. For reliability, we used ratios of different tumors to osteosarcoma for frequency analysis. We also included some data from the SEER 1973-1987 as well as from Memorial Sloan-Kettering Cancer Center, USA. RESULTS: The relative frequency of osteosarcoma (OS) is higher in China and Japan than in the United States. There were only limited number of OS patients aged over 50 years in Chinese and Japanese groups, which might be due to the lower incidence of OS subsequent to Paget's disease in Asians. More osteosarcoma occurred in the flat bones in the Americans than in the Chinese and Japanese. The relative frequency of chondrosarcoma (CS) was higher in the American group than in the Asian groups. The average age of CS patient was younger in the Chinese than in the Japanese and the Americans. The data confirmed the previous report that the incidence of Ewing sarcoma was higher in western people than in Asians. The data showed that the comparative frequency of chordoma is higher in the Americans than in the Asians and that the incidence of giant cell tumor of bone is higher in the Chinese and Japanese than in the Americans. CONCLUSIONS: The findings from this analysis provide useful information for the epidemiologic study and the clinical diagnosis of bone tumors.

Adolescent↗
PubMed1999

[Orbito-zygomatic approach for removal of tumors of the skull base].

OBJECTIVE: To evaluate the advantages and indications of orbito-zygomatic approach for removal of tumors of the skull base. METHODS: Fifteen patients with tumors of the skull base were operated on using obito-zygomatic approach. The advantages and indications of the approach were evaluated. RESULTS: In 7 cases of meningioma, total removal of the tumor was achieved in 6 cases, and subtotal removal in 1. In 4 cases of craniopharyngioma, the tumor were totally removed in 3 cases, and subtotally removed in 1. The tumor were totally removed in 2 cases of trigerminal neurilemoma and 1 case of germinoma. There was one operative death. All patients recovered except 3 who had minor extraocular parasis. CONCLUSIONS: This approach ensures additional space, and less cerebral retraction for easy access to skull base tumor, especially the large neoplasm of middle cranial base with or without orbital or posterior cranial base extension.

Adolescent↗
PubMed1999

[A clinical analysis of Mooren's corneal ulcer].

OBJECTIVE: To investigate the clinical characteristics and to compare the effects of several therapies of Mooren's corneal ulcer. METHODS: 550 consecutive in-patients with Mooren's corneal ulcer were clinically analyzed, including the age, sex, laterality of the eye, ulcer location, rate of perforation, cure rate of surgeries, recurrent rate, and the effects of conjunctiva excision, lamellar keratoplasty (LKP), LKP plus cyclosporin A eye drops. RESULTS: The average age of onset of the ulcer was 48.4 years old, the ratio of male to female was 1:0.74, bilateral disease occurred in 165 cases (30.0%) of whom 52 cases (31.5%) were in the younger group and 113 (68.5%) in the older group. There were 501 eyes (70.1%) with the ulcer located at the limbus of palpebral fissure, and 95 out of 715 eyes with the disease had corneal perforation, the rate of perforation being 13.3%, 41 cases (43.2%) in the younger group and 54 cases (56.8%) in the older group. The postoperative recurrent rate was 25.6%. The cure rate of once LKP plus cyclosporin A eye drops was 73.7%, the final cure rate was 95.6%, and the preservative rate of the corneal anatomical structure of the surgeries was 99.7%. CONCLUSION: LKP plus cyclosporin A eye drops is an effective treatment of Mooren's corneal ulcer.

Adolescent↗
PubMed1999

[An analysis of nutritional and harmful components of vegetables grown in plastic greenhouses].

OBJECTIVE: To study the changes in nutritional and harmful components of vegetables grown in plastic greenhouses. METHODS: In plastic greenhouses, microclimate and air concentrations of carbon monoxide, carbon dioxide, fluoride and respirable particulate were measured, and chlorophyll, total sugar, crude fiber, nitrite, fluoride, arsenic and some mineral elements in vegetables were determined as compared with those grown in the open-air fields. RESULTS: Greenhouse appeared a lower wind speed and darker illumination. Contents of chlorophyll a an b, total chlorophyll, reduced vitamin C, crude fiber in vegetables grown in greenhouse all were lower than those grown in open-air fields. Contents of potassium, calcium, magnesium, iron, zinc, copper and phosphorous were all lower in the vegetables grown in greenhouse than those grown in open-air fields. The contents of chlorophyll reducing Vitamin C. CONCLUSION: Lower wind speed and inadequate illumination in greenhouse affected photosynthesis and uptake of water in vegetables causing changes in their nutritional components. But, no contamination of burning coal was found in vegetables grown in greenhouse.

Air Pollutants↗
PubMed1999

[The improvement on related condition of corneal cryopreservation and roles of cryopreserved corneas in emergent keratoplasty].

PURPOSE: To study the cryopreserved corneal endothelium viability on the condition that a series of related factors on long-term corneal cryopreservation were modified. The frozen corneas were used for emergent penetrating keratoplasty on poor condition patients. To evaluate the role of cryopreserved corneas on clinical application, especially on emergent keratoplasty. METHODS: Residual peripheral corneas were stained with Trypan blue and Alizarin red in order to assess endothelium survival rate after central grafts were punched. Specular microscope was used to measure corneal thickness and count endothelium density. The transparent rate of grafts, infective control rate, retinal restorative rate and the recovery degree of visual acurity were emphasized respectively. RESULTS: Endothelium survival rate of grafts was 82.1% averagely. Postoperative endothelium density was 1,642 cells/mm2 and graft thickness was 0.59 mm averagely. The epithelial defects healed after 2-5 days of the operation and edematous grafts were reclear after 2-4 weeks of the operation in all grafts, except for chemical burn and thermal burn. The transparent rate was 87.5%. Infective controll rate was 90.63%. Retinal restorative rate was 55.56%. Some useful visual acurity can be obtained when the infection was under controlled and the retinal was reattached. CONCLUSION: Modified long-term corneal cryopreservation is effective in maintaining endothelium viability and integrity. Furthermore, it could provide donors anytime because of it's unlimited preservative duration. Our study emphasizes especially the role of cryopreserved corneas in emergent keratoplasty.

Adolescent↗
PubMed1998

Conditioned visual flight orientation in Drosophila melanogaster abolished by benzaldehyde.

To study learning and memory of Drosophila melanogaster in the flight simulator, single flies are trained in an operant conditioning paradigm to avoid a course towards visual objects that are associated with heat. The results demonstrate that normal flies (wild-type "Berlin") can quickly learn to avoid the heat-associated objects and retain the memory. This allows us to further explore a recently communicated long-term effect of preimaginal benzaldehyde (BAL) influence on the association of visual objects with the aversive odor of BAL. Here we show that flies, exposed to BAL in the embryonic, larval or adult stage, do not accompany by a similar indifference to heat shocks. The flies are successfully trained to avoid the heat-associated visual patterns. It shows that the learning acquisition is not affected during the operant conditioning in the flight simulator. Neither object perception nor object discrimination is altered after exposure to BAL, as is shown by Fourier analysis. However, the test results after training show that exposure to BAL interferes directly with memory formation in Drosophila. It takes at least two generations of growth on the noncontaminated medium that the strain recovers fully from BAL-induced amnesia. The BAL treatment seems not only to affect the associative memory formation, but in addition the flies' development in general, as is indicated by prolonged developmental time. However, the impaired memory after BAL treatment in different stages seems to have nothing to do with an influence of BAL on the cAMP-level.

Adaptation, Physiological↗