Search PubMed⌕ Search

Biomedical subjects

J Jiang

Publications and source records attributed to J Jiang.

At least 361 records · Page 20Linked to original sources
PubMed1996

Melanotropic peptide receptors: membrane markers of human melanoma cells.

The objectives of this research were to determine whether melanotropin receptors are characteristic (constant) membrane markers of human melanoma cells. Methodologies were developed to visualize these receptors by fluorescence microscopy. Multiple copies (10-20) of both [Nle4,D-Phe7]alpha-MSH, a superpotent analog of alpha-melanocyte stimulating hormone (alpha-MSH), and a fluorophore, were conjugated to polyvinyl alcohol (PVA). Incubation in the presence of the multivalent macromolecular conjugate (FITC-PVA-MSH) resulted in binding of human epidermal melanocytes and keratinocytes and human melanoma cells (both melanotic and amelanotic) to the fluorescent conjugate. Binding of the conjugate to the cells exhibited a unique cluster pattern (capping) suggesting a receptor internalization related phenomenon. Most importantly, every cell of every melanoma cell line, melanotic or amelanotic, possessed receptors as visualized by fluorescence microscopy. Since the cells were not synchronized, some binding apparently took place during all phases of the cell cycle. Therefore, receptor expression appears not to be cell-cycle dependent. Specificity of binding of FITC-PVA-MSH was demonstrated by several studies. (i) Binding of the conjugate to melanoma cells could be blocked by prior incubation of the cells in the presence of the unconjugated hormone analog; [Nle4,D-Phe7]alpha-MSH. (ii) The macromolecular conjugate lacking bound ligand (FITC-PVA) did not bind to the melanoma cells. (iii) Another peptide, a substance-P analog, attached to the substrate (FITC-PVA-SP) failed to bind to the cells. (iv) With the exception of keratinocytes, other cells of nonmelanocyte origin (e.g., fibroblasts, spleen, liver, kidney cells, and mammary cancer cells, lung cancer cells) did not bind to the conjugate. Thus, cell-specific melanotropin receptors appear to be characteristic cell surface markers of epidermal melanocytes, keratinocytes, and melanoma cells. In several human melanoma cell lines these receptors appeared to be functional since [Nle4,D-Phe7]alpha-MSH stimulated tyrosinase activity. Fluorescent melanotropin conjugates might prove useful in determining whether all human melanoma (primary and metastatic) tumors possess such receptors. These receptors might then provide targets for melanotropic peptides for the identification, localization, and chemotherapy of melanoma.

Animals↗
PubMed1996

Melanocortin receptors: identification and characterization by melanotropic peptide agonists and antagonists.

Hormones are chemical messengers released from cells to act on and control the activity of other cells. Hormonal ligands initiate their actions by interacting with receptive substances (Langley, 1906) of the target cells. These receptors are proteins that are either integral components of the cell membrane or are localized cytoplasmically within cells. Ligand-receptor interaction results in either the stimulation or inhibition of cellular activity. Since most hormones bind rather specifically to receptors possessed by their target cells, labeling of hormonal ligands can be utilized to identify and localize cells within an animal. In this report we discuss what is presently known about melanocortin receptors (MCRs) as studied by the use of labeled melanotropic peptide ligands.

Amino Acid Sequence↗
PubMed1996

Human epidermal melanocyte and keratinocyte melanocortin receptors: visualization by melanotropic peptide conjugated microspheres (latex beads).

The objectives of this research were to determine whether melanocortin receptors are characteristic (constant) membrane markers of human epidermal melanocytes. Methodologies were developed to visualize melanotropin receptors by scanning electron microscopy (SEM). Multiple copies (up to a hundred) of [Nle4,D-Phe7]alpha-MSH, a superpotent analog of alpha-melanocyte stimulating hormone (alpha-MSH), were conjugated to a macromolecular carrier (latex beads: microspheres). Incubation in the presence of the melanotropin-conjugated microspheres resulted in binding of human normal epidermal melanocytes to the beads. Almost every (possibly all) melanocyte possesses melanocortin receptors as visualized by SEM. Specificity of binding of the macromolecular conjugate was demonstrated by several studies: 1) Binding of melanocytes to the microspheres was specific since it could be blocked by prior incubation of the cells in the presence of the unconjugated hormone analog; 2) microspheres lacking bound ligand did not bind to the melanocytes; 3) microspheres that were first treated with reducing agents (e.g., dithiothreitol) did not subsequently bind to melanocytes; 4) another peptide hormone ligand (e.g., a substance-P analog) attached to the latex beads failed to bind to the cells; 5) B16/F10 mouse melanoma cells known to express melanocortin receptors bound to the microspheres; and 6) cells of nonmelanocyte origin (e.g., mammary cancer cells, small-cell lung cancer cells, fibroblasts) did not bind to the macromolecular conjugate. One exception was that human epidermal keratinocytes also expressed melanocortin receptors as determined by all the criteria established above for epidermal melanocytes. Thus, cell specific melanocortin receptors appear to be characteristic cell surface markers of epidermal melanocytes and keratinocytes.

Cells, Cultured↗
PubMed1996

Measurement of PO2 in liver using EPR oximetry.

With the use of India ink and lithium phthalocyanine (LiPc) as electron paramagnetic resonance (EPR) oximetry probes, the PO2 of the liver was investigated in mice. Because India ink was taken up by the Kupffer cells of the liver, the EPR signal of the India ink reflected the average PO2 in phagocytic vesicles of these cells. The mean value of PO2 in the Kupffer cells measured by India ink was 15.3 +/- 4.4 Torr in unanesthetized animals. LiPc was administered as a macroscopic crystal and therefore reflected the PO2 of the overall liver. The PO2 measured by LiPc was 23.4 +/- 4.4 Torr, which is consistent with the median value of 23.5 Torr reported previously with the use of an oxygen electrode. Anesthesia (injection of 60 mg/kg ip pentobarbital sodium) decreased the average PO2 in both Kupffer cells and the overall liver. The effects of perturbing the blood flow were studied by reversible blockage of the portal vein and hepatic artery in anesthetized mice; the PO2 in both Kupffer cells (measured with India ink) and in overall liver (measured with LiPc) decreased with obstruction of the blood flow and returned toward normal with reperfusion. These results indicate that the PO2 in different locations in the liver can be significantly different under both normal conditions and after perturbation by either anesthesia or ischemia. These results also demonstrate that EPR oximetry can provide sensitive measurements of PO2 in the liver in vivo under various conditions.

Anesthesia↗
PubMed1996

Growth hormone receptor cytoplasmic domain differentially promotes tyrosine phosphorylation of signal transducers and activators of transcription 5b and 3 by activated JAK2 kinase.

GH-induced activation of JAK2, a GH receptor (GHR)-associated tyrosine kinase, leads to tyrosine phosphorylation and activation of STATs (signal transducers and activators of transcription) 1, 3, and 5. The present study investigates the importance of the GHR cytoplasmic domain in the activation of STAT3 and STAT5b. As the perimembranous Box1 region of the GHR cytoplasmic domain is necessary for activation of wild-type (WT) JAK2 by GH, we examined this question using GHR/JAK2 chimeras that have an activatable JAK2 kinase domain replacing the GHR cytoplasmic domain. STAT5b and STAT3, when each was coexpressed in COS-7 cells with WT GHR and WT JAK2, were both strongly tyrosine phosphorylated in response to GH. Coexpression of STAT3 with GHR/ JAK2 chimeras resulted in a strong GH-independent tyrosine phosphorylation of STAT3 that was 40% as active as that seen with WT GHR plus WT JAK2, whereas STAT5b was more minimally phosphorylated (13% of WT GHR plus WT JAK2) when coexpressed with chimeras devoid of the GHR cytoplasmic domain. Transient coexpression of each STAT together with WT JAK2 and GHR COOH-terminal truncation mutants indicated that a GH-induced STAT3-DNA binding complex, but not a STAT5b-DNA binding complex, was detectable when a GHR devoid of 85% of the cytoplasmic domain COOH-terminus (but eliciting significant JAK2 tyrosine phosphorylation) was expressed. In vitro binding experiments using GST/GHR cytoplasmic domain fusions demonstrated that both STATs could interact at a low basal level with GHR regions distal to residue 317. Phosphorylation of tyrosine residues in those distal regions greatly enhanced the receptor's interaction with STAT5b, but not STAT3. We conclude that GH induces activation of STAT3 and STAT5b by two different pathways: one primarily dependent on activation of JAK2 (STAT3) and another that is additionally reliant on the presence of an intact and tyrosine-phosphorylated GHR cytoplasmic domain (STAT5b).

Animals↗
PubMed1996

Occurrence of conjugated cis-9,trans-11-octadecadienoic acid in bovine milk: effects of feed and dietary regimen.

Twenty-eight lactating cows were used to study the effects of different diets and different dietary regimens on the variation of cis-9,trans-11-octadecadienoic acid in milk. Cows were divided into three groups and assigned to dietary treatments differing in the ratio of forage to concentrate. The control group was fed a diet with an average ratio of forage to concentrate of 50:50. The two trial groups were fed a trial diet either in restricted or nonrestricted amounts. Variation of cis-9,trans-11-octadecadienoic acid in milk was substantial (2.5 to 17.7 mg/g of fat). Cows fed restricted amounts of the trial diet, which contained a lower forage to concentrate ratio than did the control diet, exhibited, on average, the highest concentration (11.28 mg/g of fat). For cows fed for ad libitum consumption, the trial diet did not differ significantly from the control diet (6.6 vs. 5.0 mg/g of fat). The concentration of cis-9,trans-11-octadecadienoic acid and trans-11-C18:1 was positively correlated. Therefore, conjugated linoleic acid in bovine milk, if considered to be beneficial, could be increased through a suitable dietary regimen.

Animal Feed↗
PubMed1996

A model for acute carbon monoxide poisoning in conscious rats.

These experiments were designed to establish an animal model of acute carbon monoxide (CO) poisoning in awake habituated rats. On the day before exposure, under a brief anesthesia, a Levine preparation (unilateral common carotid artery occlusion) was performed on group 1 (n = 8) and 2 (n = 28), but not on group 3 rats (n = 8). Group 1 rats were exposed to air as control. Groups 2 and 3 rats were exposed to 0.27% CO in air for 60 min [carboxyhemoglobin (HbCO) = 70%] followed by a 2-day recovery in air. The Levine preparation per se did not induce any detectable physiologic effects on group 1 rats. Identical cardiovascular and metabolic responses to CO occurred in groups 2 and 3. After the CO exposure, all group 3 rats lived for 2 days with normal neurologic index (NI). In group 2 (n = 25 post-CO), 84% of the rats showed increased NI and edema of the ipsilateral cerebral hemisphere, and 76% of the rats died 8.7 +/- 1.7 h after the CO exposure. NI correlated with the brain edema (rs = 0.748, P < 0.001) and inversely correlated with the survival time after the CO exposure (rs = -0.777, P < 0.001). We therefore may conclude that exposure of the Levine-prepared rats to 0.27% CO in air for 60 min will provide a valuable model for testing of different treatments for CO poisoning.

Animals↗
PubMed1996

Alpha-interferon for chronic active hepatitis B in human immunodeficiency virus-infected patients.

OBJECTIVES: A pilot study was conducted to evaluate the efficiency of alpha-interferon treatment in chronic active hepatitis B in anti-HIV-positive patients. METHODS: Twenty-five patients with chronic active hepatitis (23 men and 2 women, mean age: 33 years) were included in the study. Viral infections were acquired by intravenous drug addiction in 2, homosexual relations in 22, and multiple heterosexual contacts in one. The mean CD4 cell count was 480 +/- 234/mL, 7 patients had p24 antigenemia, but none belonged to class C of the CDC classification. All patients were serum HBs Ag and HBV DNA-positive, and delta antigen and antibody negative. Patients received a 6-month course of alpha-interferon 2a, 6 MU subcutaneously three times per week. The mean follow-up after treatment was 15 months. Eighteen patients with serum anti-HIV antibodies, HBsAg and HBV DNA-positive, and chronic active hepatitis, who were not treated with interferon, were included as controls (mean follow-up: 29 months). RESULTS: Nine of the 25 patients (36%) lost serum HBV DNA (1, 2, 4, 6, and 8 months after the beginning of treatment in 1, 4, 1, 2 and 1 cases, respectively), and were considered responders. Only one of the responders developed serum anti-HBe during follow-up, despite the disappearance of HBe Ag in 2 and of HBs Ag in one. Loss of HBV DNA was not clearly associated with the immune status, since 3 of the 9 responders had p24 antigenemia and the 9 responders had a lower mean CD4 count (283 +/- 246/mm3) than non responders (454 +/- 437/mm3, NS). Three of the 18 patients (16.7%) in the control group had spontaneous loss of serum HBV DNA during follow-up. Thus, there was a 2.15-fold increase in HBV DNA loss in the anti-HIV-positive patients who received alpha-interferon, compared to those who did not. CONCLUSION: In HIV-positive patients treated with alpha-interferon, the rate of HBV DNA loss was not clearly different from that reported in immunocompetent patients. As severe HBV-related liver disease has previously been described in anti-HIV positive patients, at least in drug users, these results suggest that this treatment may be proposed whatever the immune status, at least in the absence of AIDS.

Adult↗
PubMed1996

Phacoemulsification and posterior chamber intraocular lens implantation.

OBJECTIVE: The study was designed to evaluate the therapeutic effects of phacoemulsification and PMMA posterior chamber intraocular lens implantation. METHODS: The surgery was performed on 74 eyes of 67 patients with senile, complicated and congenital cataracts. RESULTS: Post-operatively, the visual acuities with spherical correction or without correction were 0.5 or better in 80.5% at one week and with correction, in 97.6% at three months. The mean astigmatism was 1.90 +/- 1.15 D at one week and 0.93 +/- 0.55 D at three months which were respectively less than that in the control group with a 10-12 mm large incision (P < 0.001), but almost the same as that in the control group with a small incision and manual nucleus division technique (P > 0.05). The main complications were iris bite in 6 eyes, capsular rupture in 2 eyes and aseptic hypopyon in one eye. The selection of cases, surgical techniques and management of intraoperative complications were discussed. CONCLUSION: These results suggest that phacoemulsification be applied extensively. However, that it has more complications and risk must be emphasized for a beginner.

Adult↗
PubMed1996

[Accommodation in pseudophakic eyes with monofocal posterior chamber intraocular lens].

OBJECTIVE: To study the accommodative problem of pseudophakic eyes with commonly implanted monofocal posterior chamber intraocular lens (PC-IOL). METHODS: Slataper's method, dynamic retinoscopy and pattern-visual evoked potentials were used to measure the accommodative power in 120 pseudophakic eyes (101 patients) with monofocal PC-IOL. RESULTS: The mean accommodative power was 2.15 +/- 0.76 D. Stepwise regression analyses revealed that the apparent accommodation is positively correlated with the corrected distant vision and the distantly corrected near vision, respectively. CONCLUSION: The apparent accommodation of pseudophakic eyes does exist, but it is a false one. The result of accommodative power measured by dynamic retinoscopy is the most objective and precise. The central visual efficiency and the applicable range of accommodation in pseudophakic eyes with low myopia (-1.00 D) are better than that in emmetropic pseudophakic eyes.

Accommodation, Ocular↗
PubMed1996

[Preliminary investigation of Helicobacter pylori infection in Linqu County of Shandong province].

A preliminary epidemiological investigation of Helicobacter pylori (HP) infection was performed with 13C-urea breathing test for 218 residents at the age from 40 to 69 years in a high risk area of gatric cancer, Linqu County of Shandong province. Our results show an overall HP infection rate of 71.10%, or 69.49% for men and 73.00% for women. The HP infection rate in the group of serious chronic atrophic gastritis was significantly higher than that of mild chronic atrophic gatritis (P < 0.05). The HP positive group also has a higher rate of complaining about gastric discomfort than the HP negative group (P < 0.02).

Adult↗
PubMed1996

Colchicine reduces hepatic fibrosis in mice infected with Schistosoma japonicum.

OBJECTIVE: Colchicine has been used clinically to treat hepatic cirrhosis caused by multiple etiologies. MATERIALS AND METHODS: The effect of colchicine on the liver fibrosis of mice infected with Schistosoma japonicum were studied. The morphological observation and morphometric analysis of the infected and untreated, and infected and treated groups were proceeded under the light microscopy, and morphological observation was made under electron microscopy. RESULTS: The results of morphometriic analysis in histological sections showed that the collagen fibers area per schistosome's egg was decreased in the infected and treated groups 10 to 13 weeks after infection. The decrease in the group of 13 weeks was significant statistically. The egg numerical density on area increased continuously from 10 to 13 weeks in both untreated and treated groups in similar degree. The ultrastructural study showed the accumulation of collagen fibrils around the hepatocytes and in the space of Disse decrease and ultrastructural lesion of hepatocytes get recovery in the treated group. CONCLUSIONS: These findings suggest that colchicine has therapeutic effect on schistosomal liver fibrosis, through not only killing off the schistosome but interfering the metabolism of collagen.

Animals↗
PubMed1996

Prevention of disability and rehabilitation--results from a collaborative project in China.

Eight different geographical districts in China varying in urban and rural characteristics from 6 provinces and 2 municipalities were selected as pilot areas of the project. The interventions included early detection and treatment of neuritis, self-care training, adapted footwear, surgery, comprehensive treatment of complicated ulcers, and prostheses. Main changes in eye, hand and foot impairments between baseline assessment and assessment at 2 years have been presented in this paper.

China↗
PubMed1996

[Protective effects of beta-carotene liposome against rat neutrophile membrane damage caused by intra- or extra-cellular reactive oxygen species].

In this experiment the protective effects of beta-carotene (beta-C) liposome against rat neutrophile membrane damage caused by extracellular or intracellular reactive oxygen were species (ROS) investigated by means of fluorescence labels 1, 6-diphenyl-1,3,5 hexatriane (DPH) and N-(3-pyrene) maleimide (N-(3p)M). The extracellular ROS include the singlet oxygen (1O2) generated by photoreaction of sensitizer rosebengal and the superoxide anion (O2-.) produced by xanthine/xanthine oxidase reactive system. The intracellular ROS was sensitizer rosebengal and superoxide anion (O2-.) produced by xanthine/xanthine oxidase reactive system while the intracellular oxygen was generated by stimulating neutrophile respiratory burst with opsonized zymosan. No change in the peak or shape of fluorescent excitation and emission spectra was found for either of the two labels. The results of fluorescent polarization value in the membrane showed that beta-C liposome could significantly inhibit the damage of rat neutrophile membrane protein reacted either by intracellular generated reactive oxygen species or by extracellular generated O2-. or 1O2. It could also inhibit the injury of the rat neutrophile membrane lipid reacted by extracellular reactive oxygen species. However, the protective effects of beta-C liposome against membrane lipid damage reacted by intracellular reactive oxygen species by at the same concentration as those on membrane protein were not significant, which could be partly explained by relatively higher damage level of rat neutrophile membrane lipid domain reacted by intracellular reactive oxygen species than that of the membrane protein domain.

Animals↗
PubMed1996

[Studies on the metabolites of tetramethylpyrazine in human urine].

Tetramethylpyrazine (TMP), an active ingredient in Chuanxiong (Ligusticum Wallich Franch), a traditional Chinese herb, has been widely used especially in the treatment of patients with cerebral ischemic diseases in China. TMP was reported to have a short half-life time because of its rapid metabolism in the liver. In this paper we studied its metabolites in human urine with GC/MS after oral administration of TMP. Three metabolites were found in the water soluble acidic fraction of the urine and the main metabolite was identified to be 3,.5,6-trimethylpyrazinecarboxylic acid.

Adult↗
PubMed1996

[Dexamethasone's effect on glutamate receptor in experimental hypoxic-ischemic cerebral injury].

In order to probe into dexamethasone's effect on glutamate receptor (Glu R) in hypoxic-ischemic encephalopathy (HIE) of newborn, we established newborn pigs' model of HIE to investigate Glu R in their forebrain crude synaptic membrane and the effect of dexamethasone in different HIE times and different dosages on the changes of Glu R. This study included five groups: HIE group (no medication); dexamethasone treatment group (10 mg/kg before HIE); dexamethasone treatment group (10 mg/kg after HIE); dexamethasone treatment group (5 mg/kg before HIE); dexamethasone treatment group (5 mg/kg after HIE). The results showed that the mean receptor density (Bmax) of dexamethasone treatment group (10 mg/kg before HIE) was significantly lower than that of the other groups (P < 0.05), but there was no statistic difference in the affinity of Glu R between all the experimental groups. These findings suggested that the preventive use of dexamethasone in large dosage would reduce the binding of Glu, and could possibly protect the brain tissues from damage in HIE.

Animals↗
PubMed1996

[Restriction fragment length polymorphism assays of clinical isolated human cytomegalovirus strain genomic DNA].

Ten clinical isolated strains of Human cytomegalovirus (HCMV) were obtained from 73 urine specimens of different people. Isolations from urine were carried out in human embryolung fibroblasts. Viral isolates were passaged four times. HCMV DNAs of laboratory strain AD169 and 10 clinical isolated strains were extracted with Hirt method, digested with each of the restriction enzymes EcoRI, Hind II. Comparison of restriction fragment length polymorphism (RFLP) of AD169 and isolated strains were made by hybridizing digested DNA with 32P labeled with HCMV Hind II cloned subgenomic fragments as the probe (pCM1035, pCM1015). pCM1035 is located in the joining region between the long(L) and short (S) unique sequences of the virus (L-S junction) pCM1015 is located in the terminal sequences of the virus. The results showed the genomic high degree of homology existed among all strains and the variable restriction site was in the L-S junction and terminal portion. The RFLP patterns of the clinical isolates which did not have relation in epidemiology were different, but the patterns of clinical isolates related in epidemiology were quite similar. Polymorphism frequently occurred in this case of EcoRI digested fragment hybridized with the probe of pCM1035. Southern hybridization of HCMV isolations is useful to researches into the molecular epidemiology and pathogenesis of HCMV infection.

Adult↗