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Biomedical subjects

Lin Lin

Publications and source records attributed to Lin Lin.

At least 37 records · Page 2Linked to original sources

Analysis of DAX1 (NR0B1) and steroidogenic factor-1 (NR5A1) in children and adults with primary adrenal failure: ten years' experience.

CONTEXT: Primary adrenal failure is a life-threatening condition that can be caused by a range of etiologies, including autoimmune, metabolic, and developmental disorders. The nuclear receptors DAX1 (NR0B1) and steroidogenic factor-1 (SF1/Ad4BP, NR5A1) play an important role in adrenal development and function, and mutations in these transcription factors have been found in patients with adrenal hypoplasia. OBJECTIVE: Our objective was to investigate the prevalence of DAX1 and SF1 mutations in children and adults with primary adrenal failure of unknown etiology (i.e. not caused by congenital adrenal hyperplasia, adrenoleukodystrophy, or autoimmune disease). PATIENTS: One hundred seventeen patients were included. Eighty-eight individuals presented in infancy or childhood with adrenal hypoplasia or primary adrenal failure of unknown etiology (n = 64 46,XY phenotypic males; n = 17 46,XY gonadal dysgenesis/impaired androgenization; n = 7 46,XX females). Twenty-nine individuals presented in adulthood with Addison's disease of unknown etiology. METHODS: Mutational analysis of DAX1 (NR0B1) (including exon 2alpha/1A) and SF1 (NR5A1) was done by direct sequencing. RESULTS: DAX1 mutations were found in 58% (37 of 64) of 46,XY phenotypic boys referred with adrenal hypoplasia and in all boys (eight of eight) with hypogonadotropic hypogonadism and a family history suggestive of adrenal failure in males. SF1 mutations causing adrenal failure were found in only two patients with 46,XY gonadal dysgenesis. No DAX1 or SF1 mutations were identified in the adult-onset group. CONCLUSIONS: DAX1 mutations are a relatively frequent cause of adrenal failure in this group of boys. SF1 mutations causing adrenal failure in humans are rare and are more likely to be associated with significant underandrogenization and gonadal dysfunction in 46,XY individuals.

Adolescent↗

The neuroprotection conferred by activating the mitochondrial ATP-sensitive K+ channel is mediated by inhibiting the mitochondrial permeability transition pore.

In order to further explore the mechanisms by which activation of mitochondrial ATP-sensitive potassium channels (mitoKATP) confers neuroprotection, we investigated the role of the mitochondrial permeability transition pore (MPTP) in in vivo and in vitro models. Adult male Sprague-Dawley rats were exposed to 90 min of middle cerebral artery occlusion (MCAO) followed by reperfusion for 22 h, when neurological scores and infarct volumes were evaluated. Activating mitoKATP by infusion of 2 mmol/L diazoxide into the ventricles 20 min before MCAO or inhibiting the MPTP by infusion of 1 micromol/L cyclosporin A 15 min before reperfusion significantly increased functional score and reduced infarction volume. Subsequent intracerebroventricular infusion of 2 mmol/L atractyloside, the MPTP opener, 10 min before reperfusion significantly attenuated the neuroprotective effects of diazoxide and cyclosporin A. The swelling of mitochondria isolated from brain was evaluated by spectrophotometry and served as a measure of MPTP opening. In isolated mitochondria, 100 micromol/L atractyloside attenuated the decrease of mitochondrial swelling induced by 30 micromol/L diazoxide or cyclosporin A (0.5 or 1 micromol/L). Furthermore, 100 micromol/L diazoxide or 1 micromol/L cyclosporin A both attenuated the fluorescence intensity in isolated mitochondria loaded with rhod-2 acetoxymethylester, and 100 micromol/L atractyloside abolished the effects of diazoxide and cyclosporin A. These results suggest that activation of mitoKATP protects the brain against injury, and this is probably mediated by attenuating mitochondrial Ca2+ overload and thus inhibiting MPTP opening during brain ischemia and reperfusion.

Animals↗

Optical parameters and upconversion fluorescence in Tm3+/Yb3+-doped alkali-barium-bismuth-tellurite glasses.

Tm(3+)/Yb(3+)-doped alkali-barium-bismuth-tellurite (LKBBT) glasses have been fabricated and characterized. Density, refractive index, optical absorption, absorption and emission cross-sections of Yb(3+), Judd-Ofelt parameters and spontaneous transition probabilities of Tm(3+) have been measured and calculated, respectively. Intense blue three-photon upconversion fluorescence and near-infrared two-photon upconversion fluorescence were investigated under the excitation of a 980 nm diode laser at room temperature. Wide infrared transmission window, high refractive index and strong blue three-photon upconversion emission of Tm(3+) indicate that Tm(3+)/Yb(3+) co-doped LKBBT glasses are promising upconversion optical and laser materials.

Fluorescence↗

Multiple forms of genetic instability within a 2-Mb chromosomal segment of 3q26.3-q27 are associated with development of esophageal adenocarcinoma.

Gene amplification is one of the mechanisms to activate oncogenes in many cancers, including esophageal adenocarcinoma (EA). In the present study, we used two-dimensional restriction landmark genome scanning to clone a NotI/DpnII fragment that showed increased genomic dosage in 1 of 44 EAs analyzed. This fragment maps to 3q26.3-q27, and subsequent experiments identified two intrachromosomal amplicons within a 10-Mb DNA segment in 7 of 75 (9%) EAs. The distal amplified-core region maps centromeric to the PIK3CA locus, and a microsatellite (D3S1754) within this region exhibited significant instability (MSI), in stark contrast to the genomewide microsatellite stability found in EA. D3S1754-MSI arises in premalignant Barrett's dysplastic cells and preceded amplification of the nascent MSI allele in the corresponding EA. Seven ESTs within the amplified-core were overexpressed in amplicon-containing EAs. One of these, EST AW513672, represents a chimeric transcript that initiated from an antisense promoter sequence in the 5'UTR of a full-length LINE-1 element (L1-5'ASP). Similar chimeric transcripts encoding portions of the MET oncogene and the BCAS3 gene also were overexpressed in EAs, suggesting that L1-5'ASP activation may occur at a broad level in primary EAs. Thus, the fine dissection of a 2-Mb amplified DNA segment in 3q26.3-q27 in EA revealed multiple genetic alterations that had occurred sequentially and/or concurrently during EA development.

5' Untranslated Regions↗

Bioassay-guided isolation of antiatherosclerotic phytochemicals from Artocarpus altilis.

The cytoprotective effects of various solvent extracts of Artocarpus altilis (Parkinson) Fosberg were evaluated. The cytoprotective effects were determined in human U937 cells incubated with oxidized LDL (OxLDL) using the 4-[3-(4-iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1, 3-benzene disulfonate (WST-1) assay. The results demonstrated that the ethyl acetate extract showed cytoprotective activities. To identify the main cytoprotective components, a bioassay guided isolation of the ethyl acetate extract afforded b-sitosterol (1) and six flavonoids (2-7). Their chemical structures were established on the basis of spectroscopic evidence and comparison with literature data. Of these compounds, compound 6 was obtained from A. altilis for the first time. The cytoprotective effect offers good prospects for the medicinal applications of A. altilis.

Artocarpus↗

ATGL has a key role in lipid droplet/adiposome degradation in mammalian cells.

Lipid droplets (LDs), also called adiposomes, are found in many eukaryotic cells, and are highly upregulated in lipid-storage cells, such as adipocytes. The mechanism by which adiposomes and their component neutral lipids are degraded is an important health issue with the rapidly spreading epidemic of obesity. Recently, a novel triglyceride lipase (adipose triglyceride lipase (ATGL)) that catalyses the initial step in triglyceride hydrolysis in adipocyte LDs was identified. Here, we show that ATGL also functions in non-adipocyte cells, and has an important role in LD degradation in these cells. Overexpression of wild-type ATGL causes a marked decrease in LD size, whereas a catalytically inactive mutant retains the ability to localize to LDs, but is unable to decrease their size. Depletion of ATGL by RNA interference leads to a significant increase in the size of LDs. These results show that ATGL has an important role in LD/adiposome turnover in mammalian cells.

Adipocytes↗

Rat adipose-derived stromal cells expressing BMP4 induce ectopic bone formation in vitro and in vivo.

AIM: Bone morphogenetic protein 4 (BMP4) is one of the main local contributing factors in callus formation in the early phase of fracture healing. Adipose-derived stromal cells (ADSC) are multipotent cells. The present study was conducted to investigate the osteogenic potential of ADSC when exposed to adenovirus containing BMP4 cDNA (Ad-BMP4). METHODS: ADSC were harvested from Sprague-Dawley rats. After exposure to Ad-BMP4, ADSC were assessed by alkaline phosphatase activity (ALP) assay, RT-PCR and von Kossa staining. BMP4 expression was assessed by RT-PCR, immunofluorescence and Western blot analysis. ADSC transduced with Ad-BMP4 were directly injected into the hind limb muscles of athymic mice. ADSC Ad-EGFP(enhanced green fluorescence protein) served as controls. All animals were examined by X-ray film and histological analysis. RESULTS: The expression of BMP4 was confirmed at both mRNA and protein levels. The expression of the osteoblastic gene, ALP activity and von Kossa staining confirmed that ADSC transduced with Ad-BMP4 underwent rapid and marked osteoblast differentiation, whereas ADSC transduced with Ad-EGFP and cells left alone displayed no osteogenic differentiation. X-ray and histological examination confirmed new bone formation in athymic mice transplanted with ADSC transduced with Ad-BMP4. CONCLUSION: Our data demonstrated successful osteogenic differentiation of ADSC transduced with Ad-BMP4 in vitro and in vivo. ADSC may be an ideal source of mesenchyme lineage stem cells for gene therapy and tissue engineering.

Adenoviridae↗

Expression and effect of inhibition of the ubiquitin-conjugating enzyme E2C on esophageal adenocarcinoma.

Ubiquitin-dependent proteolysis of cyclins plays a critical role in cell cycle progression and tumorigenesis. We examined the expression of ubiquitin-conjugating enzyme E2C (UBE2C) during progression from Barrett's metaplasia to esophageal adenocarcinoma (EA) and the effects of targeting this enzyme on EA-derived cell lines. Using oligonucleotide microarrays UBE2C expression was elevated in 73% (11 of 15) of EAs relative to Barrett's metaplasia. Tissue microarray showed elevated UBE2C in 70% (7 of 10) of dysplastic samples and in 87% (58 of 67) of tumors relative to metaplastic samples. Transfection of dominant-negative UBE2C into Seg-1 cells decreased proliferation (P = .04) and increased mitotic arrest compared to vector controls (63.5% vs 6.8%; P < .001). Transfection of UBE2C small interfering RNA also caused inhibiton of cell proliferation and distortion of the cell cycle, with maximal increase of G(2) cells (155% of mock cells) at 72 hours and of S-phase cells (308% of mock cells) at 24 hours. Treatment of Seg-1 cells with the proteasome inhibitor MG-262 (1 nM-1 microM) showed decreased proliferation (P = .02). EA-derived cells expressing UBE2C are sensitive to treatment with MG-262 and to silencing of UBE2C, suggesting that patients with EAs overexpressing UBE2C may benefit from agents targeting this ubiquitin-conjugating enzyme.

Adenocarcinoma↗

Elevated cysteine-rich 61 mediates aberrant collagen homeostasis in chronologically aged and photoaged human skin.

Alterations of human skin connective tissue structure and function are prominent features of chronological aging and solar UV irradiation-induced premature aging (photoaging). These skin connective tissue abnormalities result, in part, from reduced synthesis and elevated degradation of type I collagen, the major structural protein in skin. Here, we report that cysteine-rich 61 (CYR61/CCN1), a novel mediator of collagen homeostasis, is predominantly expressed in human skin connective tissue and is significantly elevated in fibroblasts in chronologically aged (80+ years) and photoaged human skin in vivo. In cultured human skin fibroblasts, elevated CYR61 expression substantially reduces type I procollagen and concurrently increases matrix metalloproteinase-1 (MMP-1), which initiates fibrillar collagen degradation. Elevated CYR61 caused down-regulation of transforming growth factor-beta type II receptor mRNA and protein levels, thereby impairing the transforming growth factor-beta pathway, which reduced type I procollagen and raised MMP-1 expression. Furthermore, elevated CYR61 induced transcription factor activator protein-1 (AP-1), which functions to stimulate MMP-1 expression. Thus, elevated expression of CYR61 in human skin fibroblasts acts through multiple pathways to cause alterations of collagen homeostasis similar to those pathways observed in aged human skin in vivo. These data identify CYR61 as a pivotal regulator of collagen production and degradation in aged and photoaged human skin.

Adult↗

[Effects of heat shock protein gp96 on function of macrophages from mouse].

BACKGROUND & OBJECTIVE: Heat shock protein gp96 (HSPgp96) plays an important role in antigen presenting and specific antitumor immunotherapy, but its effects on macrophages need further investigation. This study was to investigate the effects of HSPgp96 derived from H22 tumor cells on mouse peritoneal elicited macrophages (PEMphi) by detecting some factors that are related to the function of the macrophages. METHODS: After macrophages were stimulated by HSPgp96, dynamic changes of intracellular free calcium (Ca2+), nitric oxide (NO) and reactive oxygen species (ROS) in the macrophages were measured by the laser scanning confocal microscopy (LSCM) with sensitive fluorescent dye Fluo-3/AM, DAF-FM-DA, and H2DCF-DA. The color immunofluorescence assay was used to observe the expression intensity and distribution of MHC II and CD86 in the macrophages. RESULTS: The production of Ca2+, NO and ROS increased rapidly in the macrophages after stimulation of HSPgp96. Their concentration peaks appeared at 30 s, 80 s, and 580 s after stimulation with the increase scopes of (161.06+/-70.99)%, (77.58+/-31.17)%, and (647.28+/-185.70)%, respectively. The positive rates of MHC II and CD86 were significantly higher in 60 mg/L HSPgp96-stimulated macrophages than in control macrophages [(61.8+/-5.1)% vs. (40.9+/-3.5)%, P<0.01; (54.9+/-2.0)% vs.(23.1+/-3.1)%, P<0.01]. CONCLUSION: The in vitro stimulation of HSPgp96 may enhance the production of Ca2+, NO and ROS in mouse PEMphi, and up-regulate the expression of MHC II and CD86.

Animals↗

[A retrospective study of one case of human infection by the highly pathogenic avian influenza A (H5N1)].

OBJECTIVE: To describe the clinical features of the infection caused by the highly pathogenic avian influenza A (H(5)N(1)). METHODS: A previously healthy 24 year old woman presented to our hospital on November 7, 2005. She was confirmed to be an H(5)N(1) infected case after death. The clinical, radiological and epidemiological data were analyzed. RESULTS: The patient had a history of direct contact with diseased and dead poultry (chicken and duck). The disease course was 10 days from onset of illness to death, and fever preceded dyspnea by 5 days. On admission, the striking characteristics were acute community-acquired pneumonia (CAP) and acute respiratory distress syndrome (ARDS), and the major radiographic abnormalities included extensive infiltration bilaterally, focal consolidation and air bronchograms. The radiographic and clinical deterioration was rapid, and the patient died in less than 3 days after hospitalization. The diagnosis of influenza A (H(5)N(1)) was confirmed by means of reverse transcriptase-polymerase chain reaction (RT-PCR) and real-time PCR on specimens of the lower respiratory tract, performed by Chinese Center for Disease Control. The postmortem examination showed bronchial hyperemia, extensive consolidation, serous cavity effusions, disseminated intravascular coagulation (DIC) and multiple organ failure (MOF). CONCLUSIONS: Human infection by the highly pathogenic avian influenza A (H(5)N(1)) is a fatal communicable disease. Information of avian influenza A (H(5)N(1)) virus, more attention to the epidemiologic data, and early intervention are critical in reducing the mortality.

Adult↗

Steroidogenic factor-1 (SF-1) and its relevance to pediatric endocrinology.

Steroidogenic factor-1 (SF-1) (NR5A1) is a member of the nuclear receptor superfamily that is expressed widely throughout the adrenal and reproductive axes during development and plays a central role in the function of these endocrine systems in post-natal and adult life. Much has been learned about the role of this transcription factor since its initial cloning in 1992, largely due to the creation of an Sf-1 (FtzF1) knockout mouse model, in vitro studies of nuclear receptor function and, more recently, following identification and characterization of patients with naturally-occurring SF-1 mutations. In this review, we will summarize how our knowledge of SF-1 in endocrine development and disease evolved to its current state, focusing on the spectrum of phenotypes associated with mutations in this transcription factor in patients who might present to a pediatric endocrinologist.

Animals↗

[Separation of enantiomers of amino acid derivatives by high performance liquid chromatography on teicoplanin chiral stationary phase].

Direct enantioseparations of seven N-fluorenylmethoxycarbonyl-amino acids (Fmoc-Val, Fmoc-Ser, Fmoc-Leu, Fmoc-Ile, Fmoc-Met, Fmoc-Ala, and Fmoc-Phe) were achieved by high performance liquid chromatography using a 250 mm x 4. 6 mm i.d. column bonded teicoplanin on silica gel as chiral stationary phase and methanol-acetic acid-triethylamine mixtures as mobile phase. The comparison of retention behavior and enantioseparation of N-Fmoc-Val and its non-blocked analogue on a Chirobiotic column with different mobile phase systems is presented. The effects of the content of acetic acid and triethylamine and the content ratio of acetic acid and triethylamine in the mobile phase on the enantioseparation of some N-Fmoc-amino acids were examined. The results showed that variations of column temperatureand flow rate of mobile phase also had effects on enantioseparation of N-Fmoc-amino acids. The method had been successfully applied to the determination of optical purity of some derivatized amino acids.

Amino Acids↗

Arsenite induces a cell stress-response gene, RTP801, through reactive oxygen species and transcription factors Elk-1 and CCAAT/enhancer-binding protein.

RTP801 is a newly discovered stress-response gene that is induced by hypoxia and other cell stress signals. Arsenic is a heavy metal that is linked to carcinogenesis in humans. Here, we investigated the mechanism by which arsenic induces RTP801 transcription. In HaCaT human keratinocytes, arsenite was able to induce a rapid rise in the RTP801 mRNA level. Correspondingly, arsenite treatment was capable of stimulating a 2.5 kb human RTP801 promoter. Such a stimulatory effect was inhibited by co-expression of superoxide dismutase or glutathione peroxidase, and was abrogated by N-acetylcysteine, implying that ROS (reactive oxygen species) were involved in transcriptional regulation of the RTP801 gene. A series of deletion studies with the promoter revealed a critical arsenic-responsive region between -1057 and -981 bp of the promoter. Point mutations of the putative Elk-1 site and the C/EBP (CCAAT/enhancer-binding protein) site within this region were able to reduce the stimulatory effect of arsenite, indicating that Elk-1 and C/EBP are involved in transcriptional regulation of the RTP801 gene by arsenite. Furthermore, a gel mobility-shift assay demonstrated that arsenite was able to mount the rapid formation of a protein complex that bound the arsenic-responsive region as well as the C/EBP-containing sequence. The arsenite stimulation on RTP801 transcription was partly mediated by the ERK (extracellular-signal-regulated kinase) pathway, since the effect of RTP801 was inhibited by a selective ERK inhibitor. In addition, overexpression of Elk-1 and C/EBPbeta was able to elevate the promoter activity. Therefore these studies indicate that RTP801 is a transcriptional target of arsenic in human keratinocytes, and that arsenic and ROS production are linked to Elk-1 and C/EBP in the transcriptional control.

Apoptosis↗

Type 1 ryanodine receptor in cardiac mitochondria: transducer of excitation-metabolism coupling.

Mitochondria in a variety of cell types respond to physiological Ca(2+) oscillations in the cytosol dynamically with Ca(2+) uptakes. In heart cells, mitochondrial Ca(2+) uptakes occur by a ruthenium red-sensitive Ca(2+) uniporter (CaUP), a rapid mode of Ca(2+) uptake (RaM) and a ryanodine receptor (RyR) localized in the inner mitochondrial membrane (IMM). Three subtypes of RyRs have been described and cloned, however, the subtype identity of the mitochondrial ryanodine receptor (mRyR) is unknown. Using subtype specific antibodies, we characterized the mRyR in the IMM from rat heart as RyR1. These results are substantiated by the absence of RyR protein in heart mitochondria from RyR1 knockout mice. The bell-shape Ca(2+)-dependent [(3)H]ryanodine binding curve and its modulation by caffeine and adenylylmethylenediphosphonate (AMPPCP) give further evidence that mRyR functions pharmacologically like RyR1. Ryanodine prevents mitochondrial Ca(2+) uptake induced by raising extramitochondrial Ca(2+) to 10 microM. Similarly, ryanodine inhibits oxidative phosphorylation stimulated by 10 microM extramitochondrial Ca(2+). In summary, our results show that the mRyR in cardiac muscle has similar biochemical and pharmacological properties to the RyR1 in the sarcoplasmic reticulum (SR) of skeletal muscle. These results could also suggest an efficient mechanism by which mitochondria sequesters Ca(2+) via mRyR during excitation-contraction coupling to stimulate oxidative phosphorylation for ATP production to meet metabolic demands. Thus, the mRyR functions as a transducer for excitation-metabolism coupling.

Adenosine Triphosphate↗

Purification and preliminary crystallographic analysis of a Penicillium expansum lipase.

PF898 is a strain of Penicillium expansum optimized for the high level production of Penicillium expansum lipase (PEL). This PEL is unique compared with other lipases in several aspects, For example, the PEL shows low sequence identities (<30%) to all other known lipases, and high percentage of hydrophobic residues in the N-terminal region. The PEL was purified to homogeneity and shown to be 28 kDa by SDS-PAGE. Crystals suitable for X-ray diffraction analysis were obtained by the sitting-drop method of vapor diffusion with ammonia sulfate as the precipitating agent at 298 K. The crystals have tetragonal lattice and unit-cell parameters of a=b=88.09 A, c=126.54 A. Diffraction data were collected to a resolution of 2.08 A on an in-house rotating-anode generator.

Amino Acid Sequence↗

Phosphorylated FADD induces NF-kappaB, perturbs cell cycle, and is associated with poor outcome in lung adenocarcinomas.

In an effort to identify a clinical biomarker for lung cancer, we used cDNA microarray and 2D protein analyses to demonstrate that increased Fas-associated death domain (FADD) mRNA and protein were significantly associated with poor survival. Analyses of copy number and sequence of the FADD gene in 24 independent tumors ruled out the existence of an amplified and/or mutated FADD gene in aggressive lung cancers. Immunohistochemistry-based tissue microarray analysis showed that nuclear localization of FADD and elevation of the phosphorylated form of FADD (p-FADD) correlated with poor outcome (P = 0.003). Tumors with increased p-FADD expression showed elevated NF-kappaB (P = 0.004) activation, a frequent molecular alteration associated with tumorigenesis and metastasis in a variety of cancers. To provide a link between p-FADD and NF-kappaB, cell culture studies demonstrated that overexpression of p-FADD leads to an increase in NF-kappaB activity and a decrease in the number of cells in the G2 phase of the cell cycle, compared with cells expressing the nonphosphorylatable form of FADD or the vector control. Furthermore, cDNA microarray analyses of lung tumor samples showed that increased levels of FADD transcripts were significantly correlated with overexpression of cyclins D1 (P < 0.01) and B1 (P < 0.01), genes that are involved in the regulation of cell cycle progression and are inducible by NF-kappaB. These studies demonstrate that induction of NF-kappaB activity and its effects on cell-cycle progression may represent a molecular basis underlying the aggressive tumor behavior associated with elevated p-FADD expression in lung adenocarcinoma.

Adaptor Proteins, Signal Transducing↗