Biomedical subjects

X Jin

Publications and source records attributed to X Jin.

At least 91 records · Page 5Linked to original sources

PubMed1999

Capillary electrophoresis/tandem mass spectrometry for analysis of proteins from two-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis.

Capillary electrophoresis/time-of-flight mass spectrometry(CE/TOFMS) has been used for analysis of in-gel digests of protein spots excised from two-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis (2-D SDS-PAGE). An off-line purification and preconcentration procedure with a Zip Tip is used before CE/TOFMS analysis which allows for detection of protein spots with <1 picomole of material from 2-D gels. The off-line procedure provides sufficient purification for analysis while maintaining the quality of the CE separation. Using this procedure, several proteins from Coomassie Blue and zinc negatively stained gels are identified by the peptide maps generated and database searching. CE/TOF tandem mass spectrometry is used for the confirmation of database searching results and structural analysis of peptides that do not match the expected peptide maps obtained from the database in order to identify structural modifications. Several modifications were pinpointed and identified by this method.

Adenocarcinoma↗

PubMed1999

Molecular tracking of an Human Immunodeficiency Virus nef specific cytotoxic T-cell clone shows persistence of clone-specific T-cell receptor DNA but not mRNA following early combination antiretroviral therapy.

The mechanisms that lead to maintenance of an active effector cytotoxic T-cell (CTL) response in Human Immunodeficiency Virus type-1 (HIV-1) infection are not well understood. We have investigated the role of antigen in maintenance of an HIV-1 specific CTL response by studying a patient (313-7) whose antigenic stimulus was reduced using antiretroviral drug therapy started within 90 days of HIV-1 infection. This patient made a primary monospecific CTL response to an HLA-C*0802 restricted epitope in nef (KAAVDLSHFL) prior to treatment. Within 7 days of starting treatment the nef specific CTL precursor frequency (CTLp) had decreased from 60/10(6) to 4/10(6) peripheral blood mononuclear cells (PBMC), coincident with a decline in viremia from 18 470 to 615 copies/ml. Both plasma viremia and nef specific CTLp remained at low levels for 180 days. The nef-specific CTL clone T-cell receptor (TCR) mRNA transcripts also decreased after treatment, but clone specific TCR DNA persisted. It appears that removal of antigen alters the state of HIV specific CTL from an activated effector population (detected in the CTLp assay and by measurement of clone specific RNA) to a non-activated quiescent population (detected by measurement of clone-specific DNA). This latter population may represent persisting HIV specific memory CTL.

Adult↗

PubMed1999

Comparison of restimulation methods to elicit SIV specific cytotoxic T-lymphocytes (CTL) in vitro: Staphylococcal enterotoxin B (SEB) provides a novel method for the quantification of SIV specific CTL precursors.

Most investigators believe that an effective HIV-1 vaccine will have to induce high levels of HIV-1 specific cytotoxic T-cells (CTL). The macaque SIV challenge/protection model system has been used to test candidate vaccines, but quantitative immunogenicity measurements are difficult due to technical limitations of the assays available. The quantification of SIV specific CTLp is crucial to understanding correlates of immunity for these vaccines, but are difficult to measure. We have compared various methods to quantify SIV specific CTLp, and describe a novel method of SIV specific CTL in vitro stimulation using the superantigen Staphylococcal enterotoxin B (SEB). SEB can stimulate high levels of CTLp in vitro, and provides an alternative method to induce SIV specific CTL.

Animals↗

PubMed1999

The effect of commencing combination antiretroviral therapy soon after human immunodeficiency virus type 1 infection on viral replication and antiviral immune responses.

Twelve subjects were treated with zidovudine, lamivudine, and ritonavir within 90 days of onset of symptoms of acute infection to determine whether human immunodeficiency virus type 1 (HIV-1) infection could be eradicated from an infected host. In adherent subjects, with or without modifications due to intolerance, viral replication was suppressed during the 24-month treatment period. Durable suppression reduced levels of HIV-1-specific antibodies and cytotoxic T lymphocyte responses in selected subjects. Proviral DNA in mononuclear cells uniformly persisted. The persistence of HIV-1 RNA expression in lymphoid tissues and peripheral blood mononuclear cells suggests that elimination of this residual pool of virus should be achieved before considering adjustments in antiretroviral therapeutic regimens. In addition, given the reduction in levels of virus-specific immune responses, it would seem prudent to consider enhancing these responses using vaccine strategies prior to the withdrawal of antiviral therapy.

Acquired Immunodeficiency Syndrome↗

PubMed1999

Three new species of the genus Actinobispora of the family Pseudonocardiaceae, Actinobispora alaniniphila sp. nov., Actinobispora aurantiaca sp. nov. and Actinobispora xinjiangensis sp. nov.

The genus Actinobispora Jiang et al. is characterized by the formation of longitudinally paired spores on both the vegetative and the aerial mycelium, absence of mycolic acid, cell wall chemotype IV (containing meso-diaminopimelic acid as the diamino acid, galactose and arabinose), PVI and MK-9(H2). Comparative studies of morphology, chemical classification and phylogenetic analysis based on the 16S rRNA sequences among the four type strains of the genus Actinobispora and type strains of related genera were carried out. The results indicated that the genus Actinobispora is different from these other genera and should be placed in the family Pseudonocardiaceae Embley et al. 1988 with the genera Amycolatopsis, Pseudonocardia, Saccharomonospora, Saccharopolyspora and Actinopolyspora. On the bases of these results, three new species under the names of Actinobispora alaniniphila sp. nov., Actinobispora aurantiaca sp. nov. and Actinobispora xinjiangensis sp. nov. are proposed; the type strains are CCTCC AA97001T, CCTCC AA97002T and CCTCC AA97020T.

Actinomycetales↗

PubMed1999

Strong human immunodeficiency virus (HIV)-specific cytotoxic T-lymphocyte activity in Sydney Blood Bank Cohort patients infected with nef-defective HIV type 1.

Proposals for the use of live attenuated human immunodeficiency virus (HIV) type 1 (HIV-1) as a vaccine candidate in humans have been based on the protection afforded by attenuated simian immunodeficiency virus in the macaque model. Although it is not yet known if this strategy could succeed in humans, a study of the Sydney Blood Bank Cohort (SBBC), infected with an attenuated HIV-1 quasispecies with natural nef and nef/long terminal repeat deletions for up to 17 years, could provide insights into the long-term immunological consequences of living with an attenuated HIV-1 infection. In this study, HIV-specific cytoxic T-lymphocyte (CTL) responses in an SBBC donor and six recipients were examined over a 3-year period with enzyme-linked immunospot, tetrameric complex binding, direct CTL lysis, and CTL precursor level techniques. Strong HIV-specific CTL responses were detected in four of seven patients, including one patient with an undetectable viral load. Two of seven patients had weak CTL responses, and in one recipient, no HIV-specific CTLs were detected. High levels of circulating effector and memory HIV-specific CTLs can be maintained for prolonged periods in these patients despite very low viral loads.

Acquired Immunodeficiency Syndrome↗

PubMed1999

Decay kinetics of human immunodeficiency virus-specific effector cytotoxic T lymphocytes after combination antiretroviral therapy.

Little is known of the changes in human immunodeficiency virus type 1 (HIV-1)-specific effector cytotoxic T lymphocytes (CTL) after potent antiretroviral therapy. Using HLA/peptide tetrameric complexes, we show that after starting treatment, there are early rapid fluctuations in the HIV-1-specific CTL response which last 1 to 2 weeks. These fluctuations are followed by an exponential decay (median half-life, 45 days) of HIV-1-specific CTL which continues while viremia remains undetectable. These data have implications for the immunological control of drug-resistant virus.

ADP-ribosyl Cyclase↗

PubMed1999

HIV-1-specific immune responses in subjects who temporarily contain virus replication after discontinuation of highly active antiretroviral therapy.

Therapeutic intervention with highly active antiretroviral therapy (HAART) can lead to suppression of HIV-1 plasma viremia to undetectable levels for 3 or more years. However, adherence to complex drug regimens can prove problematic, and subjects may temporarily discontinue HAART for variable periods. We studied 6 HIV-1-infected individuals who stopped therapy. Off HAART, levels of viremia were suppressed to fewer than 500 copies/mL in 2 subjects for more than 12 and more than 24 months, respectively, and in 1 subject for 4 months on 1 occasion. Three subjects failed to contain plasma viremia. Broad and strong HIV-1-specific immune responses were detected in subjects with prolonged suppression of viral replication. This longitudinal study suggests that containment of HIV-1 replication to low or undetectable levels after discontinuation of HAART is associated with strong virus-specific immune responses. Boosting of HIV-1-specific immune responses should be considered as an adjunctive treatment strategy for HIV-1-infected individuals on HAART.

Acquired Immunodeficiency Syndrome↗

PubMed1999

Photoprotective effect of black tea extracts against UVB-induced phototoxicity in skin.

In previous studies, we showed that green tea and black tea extracts and their major polyphenolic constituents protect against UVB light-induced carcinogenesis in murine skin. All of these studies required chronic administration of tea extracts or specific constituents either topically or orally. However, it is not known whether acute or subchronic administration of black tea extracts or constituents can ameliorate UVB-induced early effects in skin. In the present study, cultured keratinocytes and mouse and human skin were employed to assess the effect of both oral and topical administration of standardized black tea extract (SBTE) and its two major polyphenolic subfractions namely BTF1 and BTF2 against UVB-induced photodamage. In SKH-1 hairless mice, topical application of SBTE (0.2 mg/cm2) prior to UVB exposure (180 mJ/cm2) resulted in 40% reduced incidence and 64% reduced severity of erythema and 50% reduction in skinfold thickness by day 6 when compared to nontreated UVB-exposed animals. The SBTE was also effective in protecting against UVB-induced erythema in human volunteers. Administration of SBTE 5 min after UVB irradiation was similarly effective in reducing UVB-induced inflammation in both murine and human skin. The major polyphenolic subfractions, BTF1 and BTF2, were also effective in protecting in mouse skin. The SBTE subfractions inhibited UVB-induced tyrosine phosphorylation of epidermal growth factor receptor (EGFR). The UVB irradiation of human epidermoid carcinoma cells resulted in 3.3-fold induction of tyrosine phosphorylation of EGFR. Pretreatment with BTF1 and BTF2 reduced tyrosine phosphorylation of EGFR by 53% and 31%, respectively. The UVB-mediated enhanced expression of the early response genes, c-fos and c-jun in human epidermal keratinocytes was reduced in a dose-dependent manner by SBTE. Topical application of SBTE was also effective in reducing accumulation of c-fos and p53 proteins by 82% and 78%, respectively, in UVB-exposed mouse skin. These data provide evidence that constituents of black tea can abrogate UVB-induced erythema and associated early events in murine and human skin.

Administration, Oral↗

PubMed1999

An experimental study of electro-acupuncture on auditory impairment caused by kanamycin in guinea pigs.

Frequency following response (FFR) and auditory brain stem evoked potential response (ABR) were used to determine the auditory acuity in evaluating the effect of electro-acupuncture treatment of kanamycin-induced auditory impairment in guinea pigs. The succinate dehydrogenase (SDH) activity and morphological changes of the inner ear receptors were examined under the light and scanning electron microscope in cochlear spread preparations. The results showed that 1) electro-acupuncture was effective but no significant differences were found among the stimulating wave forms; 2) Tinggong (SI 19), Yifeng (SJ 17), Shenshu (UB 23), Sanyinjiao (Sp 6), Zhubin (K 9) and Waiguan (SJ 5) are all effective acupoints, especially the combination of Tinggong (SI 19), Sanyinjiao (Sp 6) and Zhubin (K 9) acupoints; 3) improvement in the cochlear function and excitability of the cortical and lower auditory center and increase of the mitochondrial SDH activity and energy supply in hair cells might contribute to the mechanism of the treatment.

Animals↗

PubMed1999

Characterization of human A(2B) adenosine receptors: radioligand binding, western blotting, and coupling to G(q) in human embryonic kidney 293 cells and HMC-1 mast cells.

Recombinant human A(2B) adenosine receptors (A(2B)ARs) and receptors extended on the amino terminus with hexahistidine and the FLAG epitope, DYKDDDDK (H/F-A(2B)) were stably overexpressed (to >20,000 fmol/mg protein) in human embryonic kidney 293 cells (HEK-A(2B)). By Western blotting, the H/F-A(2B) receptor runs as a 34.8-kDa glycoprotein. Pharmacological properties of A(2B)ARs were characterized with (125)I-3-aminobenzyl-8-phenyl-(4-oxyacetic acid)-1-propylxanthine (K(D), 36 nM). In competition binding assays, the affinity of agonists is reduced by substitution on either the N(6)- or the C-2 position of the adenine ring, whereas 5'-substitutions increase affinity, resulting in the potency order: 5'-N-ethylcarboxamidoadenosine (NECA) >> N(6)-aminobenzyl-NECA approximately 2-chloroadenosine > 2-[4-(2-carboxyethyl)phenethylamino]-NECA (CGS21680) > N(6)-aminobenzyladenosine. The A(2B)AR is potently blocked by the A(2A)-selective antagonist 4-(2-[7-amino-2-[2-furyl][1,2, 4]triazolo-[2,3-a][1,3,5] triazin-5-yl-amino]ethyl)phenol (ZM241385; K(I), 32 nM for A(2B), 1.4 nM for A(2A)) and the A(1) selective antagonist 8-cyclopentyl-1,3-dipropylxanthine (K(I), 50.5 nM for A(2B); 2.5 nM for A(1)). The K(I) values for the antiasthmatic xanthines, theophylline (7.8 microM) and enprofylline (6.4 microM), are below their therapeutic plasma concentrations (20 to 50 microM), and agree with K(I) determinations for inhibition of NECA-stimulated cAMP accumulation in HEK-A(2B) cells. NECA or N(6)-(2-iodo)benzyl-5'-N-methylcarboxamidodoadenosine (IB-MECA) stimulate inositol trisphosphates and calcium accumulation in HEK-A(2B) or HEK-A(3) cells, respectively, but only the A(3) response is prevented by pertussis toxin. In human HMC-1 mast cells, A(2B)AR activation stimulates calcium mobilization and cAMP accumulation. We conclude that HEK-A(2B) cells and HMC-1 mast cells possess A(2B)AR glycoproteins that are coupled to both G(q/11) and G(s).

Animals↗

PubMed1999

Changing pattern of heart diseases in Shanghai from the 1950s to 1980s.

OBJECTIVE: To determine the pattern of dynamic change in types of heart diseases in the past 4 decades for providing a reference to treatment and prevention of heart diseases in China. METHODS: All adult cardiac patients admitted to the Zhong Shan Hospital and Hua Shan Hospital from 1948 to 1989 were analyzed. The constituent ratio of different heart diseases in the 1950s, 1960s, 1970s and 1980s was compared. RESULTS: The percentage of heart diseases among medical inpatients increased in each of the recent 4 decades, from 9.89%, 15.69%, 20.90% to 23.54% respectively. The constituent ratio of different heart diseases changed, coronary heart disease constituted the highest proportion, next came rheumatic heart disease, and congenital heart disease was in third place. Congenital heart disease, myocarditis, cardiac dysrhythmia without organic heart disease, cardiomyopathy and endocarditis increased, rheumatic heart disease, pulmonary heart disease and hypertensive heart disease apparently decreased; syphilitic heart disease could rarely be encountered. CONCLUSION: China is now facing a low overall death rate, a long life expectancy and an aging population. The incidence of heart diseases increased gradually and patterns of heart diseases kept changing. The overall trend is that heart diseases which were not related to infection are increasing while heart diseases related to bacterial infection are decreasing.

Arrhythmias, Cardiac↗

PubMed1999

[A clinico-pathological and immunohistochemical study on anaplastic large cell lymphoma].

OBJECTIVE: To study the clinicopathological characteristics, immunophenotype and biologic behavior of anaplastic large cell lymphoma (ALCL). METHODS: Clinicopathological and immunohistochemical methods (ABC method) were used to analyse 8 cases of ALCL and followed for 6 to 25 months. RESULTS: Eight ALCL patients (4 male and 4 female) accounted for 4.1% of the 195 lymphomas seen from 1994 to 1997. Average age was 40 years. Two tumors were located in the skin, the remainder were systemic. Clinical stage: stage I, 2 cases; stage II, 1 case; stage III, 5 cases. Histopathology: Tumor cells exhibited high pleomorphism and a large amount of mitotic figures. Reactive components (cells) often observed in the background. Immunohistochemical studies found that all tumors reacted positively with CD30 and negatively with CD15. Five cases expressed T-cell's markers (CD3, UCHL-1, CD43) and three expressed B-cell markers (CD79a, L26). After chemotherapy, two patients with cutaneous type ALCL had complete remission and survived 14 and 25 months respectively. Of the six systemic cases, three survived for 6-8 months, the remaining three died at 2 days, 20 days and 18 months after diagnosis. CONCLUSIONS: This study found that ALCL was a group of lymphomas showing similarity in morphology but diversity in clinical presentation and immunophenotype. Even if the tumor is very responsive to chemotherapy, ALCL remains a high grade malignant lymphoma.

Adolescent↗

PubMed1999

[Effect of acrylonitrile on the activity of Ca(2+)-ATPase and phosphorylase A of liver in rats].

The activity of Ca(2+)-ATPase and phosphorylase A(P-A) of liver in rats was determined to study the effect of acrylonitrile (ACN) on calcium homeostasis and to clarify the toxicological mechanism of ACN. Adult male Sprague-Dawley rats were administered ACN daily per os for 42 days, at the dosage of 0, 10, 30 and 50 mg.kg-1. The activities of Ca(2+)-ATPase and phosphorylase A was determined at 14, 28, 42 days after ACN administration. The results indicated that ACN could significantly inhibit the activity of Ca(2+)-ATPase and increase the activity of P-A (P < 0.01), especially in the high dose group and exposed for 42 days, and there was significantly dose- and time-respond relationship (P < 0.01). ACN contamination could result in the disharmony of calcium homeostasis of liver in rats.

Acrylonitrile↗

PubMed1999

[Light-dependent incorporation of selenite into selenocysteine by isolated chromatophore of Chromatium vinosum].

Illiminated intact chromatophore of chromatium vinosum in the presence of O-acetylserine(OAS) catalysed incorporation of SeO3(2-) into selenocysteine at rate of 359 nmol.mgBchl-1.h-1. Sonicated chromatophore catalysed SeO3(2-) incorporation at 1.1% of the rate of intact chromatophore. Addition of GSH and NADPH increased the rate to 88.3% of intact rate, but SeO3(2-) incorporation under these conditions was essentially light dependent. The purified GSH reductase from Chromatium vinosum in the presence of cysteine synthase OAs and NADPH catalysed incorporation of SeO3(2-) into selenocysteine. It is proposed that SeO3(2-) is reduced by light-coupled GSH reductase and that Se2- produced is incorporated into selenocysteine by cysteine synthase.

Catalysis↗

PubMed1999

Diagnosis of trichinosis by indirect fluorescent antibody test with Trichinella larva section.

AIM: To evaluate the value of indirect fluorescent antibody test (IFAT) in diagnosing trichinosis. METHODS: IFAT using frozen section of the purified Trichinella larvae as antigen was employed to detect anti-Trichinella antibodies in sera from mice infected with Trichinella spiralis and the patients with trichinosis. Sera from patients with trichinosis were collected at different time intervals after onset of the disease and after treatment with albendazole. Sera from patients with other parasitic diseases and healthy individuals were used as control. RESULTS: The anti-Trichinella antibodies were detected in 15 infected mice as early as 2 weeks after infection, and in 86.5% of 467 patients with trichinosis. Sera from patients with filariasis, echinococcosis and healthy controls were all negative. 8 of 48 (16.7%) cases with paragonimiasis showed positive cross reaction. The antibody positive rate of patients with trichinosis was 70.2% one week after onset of disease and increased to 91.0%, 95.8% and 100% at two, three and four weeks after onset, respectively. The frozen section of the larvae can be stored at -20 degrees C for 5 years without loss of antigenicity. The IFAT positive rate was increased from 87.5% before treatment to 100% one week after treatment, and the serum antibody titers were elevated as well. The antibody negative conversion rate of the patients was 24% at one month after teratment and increased to 75% at four months after treatment. CONCLUSION: IFAT using frozen section of the purified Trichinella larvae as antigen is highly sensitive and specific for the diagnosis of trichinosis and evaluation of the therapeutic effect.

Animals↗

PubMed1999

[Study on the correlation between the cyclin D1 and laryngeal squamous cell carcinoma].

OBJECTIVE: To study the correlation between the expression level of Cyclin D1 and the laryngeal squamous cell carcinoma (LSCC). METHOD: 35 LSCC cases testified pathologically were included in the study. The samples obtained from each tumor tissue and adjacent normal mucosa were detected to see the expression level of Cyclin D1 with the method of RT-PCR and light density half quantive analysis. RESULT: The expression level of Cyclin D1 was significant higher in almost all turmor tissues than in the adjacent normal mucosae (P < 0.05). Overexpressed carcinomas were more frequently associated with lymph node metastases (P < 0.05). A significant association between the expression level of Cyclin D1 and TNM was found. The higher T stage, the higher the expression level of Cyclin D1 (P < 0.01). The expression level of low histological grade carcinomas was lower than that of the high histological grade carcinomas, but the difference had no statistical significance. No association between overexpression of Cyclin D1 and sex, age was found too. CONCLUSION: The result indicates that the expression level of Cyclin D1 in LSCC may be a useful marker of prognostic significance and it provide a molecular biology basis for treating the LSCC patients.

Aged↗

PubMed1999

[Effects of combined treatment with flouride and 1,25-dihydroxyvitamin D3 on the histomorphometry and biomechanical properties of bone in ovariectomized rats].

OBJECTIVE: To evaluate the potential use of a combination of bone formation-promoting agents and a differentiation agent of osteoblast as a treatment for postmenopausal osteoporosis. METHODS: The effects of combined and separate administration of flouride-Ca (0.45 ng F- + 13.56 mg Ca2+)/(kg.d) and 1,25-dihydroxyvitamin D (135 pmol/d s.c.) on the histomorphometric parameters in the secondary spongiosa of proximal tibia and biomechanical properties of femoral midshaft in ovariectomized (OVX) rats were examined. RESULTS: Compared with OVX group, OVX + fluoride-Ca group (O + F) and OVX + Fluoride-Ca + 1,25-dihydroxyvitamin D(O + F + D) two kinds of treatment caused 42%, 91% more in %Tb Ar, 14%, 38% more in Tb Wi, 24%, 46% more in Tb N, 26%, 43% less in Tb Sp, 45%, 42% less in % E Pm, 30%, 60% more in Ob Pm respectively. W Wi in O + F treatment had no significant difference from OVX group but 15.2% in O + F + D treatment compared with sham group, MLT increased 16% in O + F group, had no difference from O + F + D. No significant alteration of mechanical strength at femoral midshaft in both O + F and O + F + D was found. There were significant difference in above changes of parameters except % Ob Pm. CONCLUSIONS: Above two treatments could prevent the loss of cancellous bone, reduced the resorption caused by OVX, protected trabecular microarchitecture, and stimulated bone formation significantly. The combined treatment avoided potential mineralization defect caused by F-Ca treatment alone, and two treatments maintained mechanical strength at femoral midshaft.

Animals↗