Biomedical subjects

Jie Li

Publications and source records attributed to Jie Li.

At least 253 records · Page 14Linked to original sources

PubMed2003

Laminin-10 is crucial for hair morphogenesis.

The role of the extracellular matrix in cutaneous morphogenesis is poorly understood. Here, we describe the essential role of laminin-10 (alpha5beta1gamma1) in hair follicle development. Laminin-10 was present in the basement membrane of elongating hair germs, when other laminins were downregulated, suggesting a role for laminin-10 in hair development. Treatment of human scalp xenografts with antibodies to laminin-10, or its receptor beta1 integrin, produced alopecia. E16.5 Lama5 -/- mouse skin, lacking laminin-10, contained fewer hair germs compared with controls, and after transplantation, Lama5 -/- skin showed a failure of hair germ elongation followed by complete hair follicle regression. Lama5 -/- skin showed defective basement membrane assembly, without measurable increases in anoikis. Instead, Lama5 -/- skin showed decreased expression of early hair markers including sonic hedgehog and Gli1, implicating laminin-10 in developmental signaling. Intriguingly, treatment of Lama5 -/- skin with purified laminin-10 corrected basement membrane defects and restored hair follicle development. We conclude that laminin-10 is required for hair follicle development and report the first use of exogenous protein to correct a cutaneous developmental defect.

Alopecia↗

PubMed2003

Thymus transplantation in complete DiGeorge syndrome: immunologic and safety evaluations in 12 patients.

Complete DiGeorge syndrome is a fatal condition in which infants have no detectable thymus function. The optimal treatment for the immune deficiency of complete DiGeorge syndrome has not been determined. Safety and efficacy of thymus transplantation were evaluated in 12 infants with complete DiGeorge syndrome who had less than 20-fold proliferative responses to phytohemagglutinin. All but one had fewer than 50 T cells/mm3. Allogeneic postnatal cultured thymus tissue was transplanted. T-cell development was followed by flow cytometry, lymphocyte proliferation assays, and T-cell receptor Vbeta (TCRBV) repertoire evaluation. Of the 12 patients, 7 are at home 15 months to 8.5 years after transplantation. All 7 survivors developed T-cell proliferative responses to mitogens of more than 100 000 counts per minute (cpm). By one year after transplantation, 6 of 7 patients developed antigen-specific proliferative responses. The TCRBV repertoire showed initial oligoclonality that progressed to polyclonality within a year. B-cell function developed in all 3 patients tested after 2 years. Deaths were associated with underlying congenital problems. Risk factors for death included tracheostomy, long-term mechanical ventilation, and cytomegalovirus infection. Adverse events in the first 3 months after transplantation included eosinophilia, rash, lymphadenopathy, development of CD4-CD8- peripheral T cells, elevated serum immunoglobulin E (IgE), and possible pulmonary inflammation. Adverse events related to the immune system occurring more than 3 months after transplantation included thrombocytopenia in one patient and hypothyroidism and alopecia in one other patient. Thymic transplantation is efficacious, well tolerated, and should be considered as treatment for infants with complete DiGeorge syndrome.

Child↗

PubMed2003

Stability of magnesiowustite in Earth's lower mantle.

Magnesiowüstite [(Mg,Fe)O] is the second most abundant mineral of Earth's lower mantle. Understanding its stability under lower mantle conditions is crucial for interpreting the physical and chemical properties of the whole Earth. Previous studies in an externally heated diamond anvil cell suggested that magnesiowüstites decompose into two components, Fe-rich and Mg-rich magnesiowüstites at 86 GPa and 1,000 K. Here we report an in situ study of two magnesiowüstites [(Mg(0.39),Fe(0.61))O and (Mg(0.25),Fe(0.75))O] at pressures and temperatures that overlap with mantle conditions, using a laser-heated diamond anvil cell combined with synchrotron x-ray diffraction. Our results show that addition of Mg in wüstite (FeO) can stabilize the rock-salt structure to much higher pressures and temperatures. In contrast to the previous studies, our results indicate that Mg-rich magnesiowüstite is stable in the rock-salt structure in the lower mantle. The physical and chemical properties of magnesiowüstite should change gradually and continuously in the lower mantle, suggesting that it does not make a significant contribution to seismic-wave heterogeneity of the lower mantle. Stable Mg-rich magnesiowüstite in lowermost mantle can destabilize FeO in the core-mantle boundary region and remove FeO from the outer core.

Journal Article↗

PubMed2003

LOH of chromosome 12p correlates with Kras2 mutation in non-small cell lung cancer.

Previous observation has shown that the wild-type Kras2 allele is a suppressor of lung cancer in mice. Here we report that loss of heterozygosity (LOH) of chromosome 12p was detected in approximately 50% of human lung adenocarcinomas and large cell carcinomas, and Kras2 mutations were detected at codon 12 in approximately 40% of adenocarcinomas and large cell carcinomas. Interestingly, all of the lung adenocarcinomas and large cell carcinomas containing a Kras2 mutation exhibited allelic loss of the wild-type Kras2 allele when a correlation between LOH of the region on chromosome 12p and Kras2 mutation was made. These results from human lung cancer tissues provide a strong evidence in support of our previous observation in mouse models that the wild-type Kras2 is a tumor suppressor of lung cancer.

Adenocarcinoma↗

PubMed2003

[Hearing screening for high-risk newborns].

OBJECTIVE: To investigate the morbidity of congenital hearing impairment among high-risk newborns and the relevant pathogenic factors. METHODS: Initial screening of hearing by otoacoustic emission (OAE) was conducted among 208 high-risk newborns, 130 males and 78 females after they were born and the second screening was conducted by OAE was conducted 42 days after those with positive results were examined by auditary brainstem response (ABR). RESULTS: All of the 208 newborns received the initial screening with a screening rate of 100%, and 130 newborns received the second screening with a screening rate of 62.5%. The positive rates in the initial screening and second screening were 34.61% and 7.14% respectively. Six newborns were examined by ABR and 2 of them were diagnoses as with hearing impairment with a prevalence rate of 1.78%. The factors, such as sex, age, and Apgar score affected the initial screening results. CONCLUSION: The most proper time for initial hearing screening is around the 42nd day after birth. High-risk newborns should receive regular test even though they pass the initial screening. A special follow-up system should be constructed for the high-risk newborns.

Evoked Potentials, Auditory, Brain Stem↗

PubMed2003

[Preimplantation genetic diagnosis for beta-thalassemia].

OBJECTIVE: To investigate the effect of in vitro fertilization and embryo transfer (IVF-ET) and preimplantation genetic diagnosis (PGD) for the couples at risk of having children with beta-thalassemia. METHODS: Four couples carrying different thalassemia mutations received standard IVF treatment. Embryo biopsy was conducted. Single blastomeres were genotyped by a protocol involving primer extension preamplification, nested polymerase chain reaction and reverse dot-blot analysis. Only the unaffected embryos were transferred to the uterus. RESULTS: A total of 97 oocytes were retrieved from the four female carriers. Among them, 83% showed two pronuclei. Embryo biopsy was performed on 47 of these embryos. The amplification efficiency was 84.8%. The average ADO rate was 14.9%. Ten unaffected embryos were transferred. A twin pregnancy with one blighted ovum was confirmed at 7 weeks' gestation by ultrasonography and one normal baby and one carrier of thalassemia mutation were born finally. CONCLUSION: This unaffected pregnancy resulting from PGD for beta-thalassemia demonstrates that PGD technique can be a powerful diagnostic tool for couples carrying beta-thalassemia mutations who desire a healthy child and wish to avoid abortion of an affected fetus.

Biopsy↗

PubMed2003

Exploring the optimal site for modifications of pyranmycins with the extended arm approach.

[reaction: see text] Continuing from the syntheses and the antibacterial studies of a library of pyranmycins, we further probed the proximity around ring III of pyranmycin by introducing an "extended arm" that has hydroxyethyl or aminoethyl groups at the O-2' ', O-3' ', or O-4' ' positions. The results from the antibacterial studies reveal the optimal structural motif is the attachment of an extended arm with a terminal hydroxyl group at the O-3' ' position.

Aminoglycosides↗

PubMed2003

S-nitrosothiols inhibit uterine smooth muscle cell proliferation independent of metabolism to NO and cGMP formation.

S-nitrosothiols (RSNOs) are important mediators of nitric oxide (NO) biology. The two mechanisms that appear to dominate in their biological effects are metabolism leading to the formation of NO and S-nitrosation of protein thiols. In this study we demonstrate that RSNOs inhibit uterine smooth muscle cell proliferation independent of NO. The antiproliferative effects of NO on vascular smooth muscle are well defined, with the classic NO-dependent production of cGMP being demonstrated as the active pathway. However, less is known on the role of NO in mediating uterine smooth muscle cell function, a process that is important during menstruation and pregnancy. The RSNOs S-nitrosoglutathione and S-nitroso-N-acetyl pencillamine inhibited growth factor-dependent proliferation of human and rat uterine smooth muscle cells (ELT-3). Interestingly, these cells reduced RSNOs to generate NO. However, use of NO donors and other activators of the cGMP pathway failed to inhibit proliferation. These findings demonstrate the tissue-specific nature of responses to NO and demonstrate the presence of a RSNO-dependent but NO-independent pathway of inhibiting DNA synthesis in uterine smooth muscle cells.

Animals↗

PubMed2003

Suppression of hepatitis B virus core promoter by the nuclear orphan receptor TR4.

The TR4 orphan receptor is a member of the nuclear receptor superfamily that modulates gene expression via binding to the AGGTCA direct repeat hormone response element. Here we report a functional study of TR4 interaction with the core promoter of the hepatitis B virus (HBV). The electrophoretic mobility shift assay shows that TR4 can bind to the direct repeat 1 sequence element (AGGTTAAAGGTCT, nucleotide coordinates 1757-1769, TR4RE-HBV) on the HBV core promoter. TR4 also can enhance the activity of a synthetic luciferase reporter linked with four copies of TR4RE-HBV in either liver HepG2 or non-liver H1299 cells in a dose-dependent manner. Surprisingly, TR4 represses the activity of a luciferase reporter containing the entire HBV genome sequences. Moreover, mutation of this TR4RE-HBV site in the HBV core promoter diminishes the TR4 suppression effect. This TR4-induced suppression of HBV core promoter activity is further confirmed by primer extension analysis of the HBV core RNAs, showing that TR4 represses both pre-core and core mRNAs. Further dissection of this repressive mechanism indicates that TR4 may suppress the HBV core promoter activity via repressing HNF4alpha-mediated transactivation by protein-protein interactions without inhibition of HNF4alpha DNA binding. Furthermore, our results indicate that the N- and C-terminal regions of TR4 protein are required for TR4-HNF4alpha interaction. It is possible that TR4-HNF4alpha interaction may block the HNF4alpha function that results in the suppression of HBV gene expression. Together, these results demonstrate that TR4 can serve as a negative modulator in the transcriptional regulation of HBV core gene expression.

Binding Sites↗

PubMed2003

Angiogenesis in wound repair: angiogenic growth factors and the extracellular matrix.

Angiogenesis is critical to wound repair. Newly formed blood vessels participate in provisional granulation tissue formation and provide nutrition and oxygen to growing tissues. In addition, inflammatory cells require the interaction with and transmigration through the endothelial basement membrane to enter the site of injury. Angiogenesis, in response to tissue injury, is a dynamic process that is highly regulated by signals from both serum and the surrounding extracellular matrix (ECM) environment. Vascular endothelial growth factor, angiopoietin, fibroblast growth factor, and transforming growth factor beta are among those most potent angiogenic cytokines in wound angiogenesis. The cooperative regulation of them is essential for wound repair. Migration of endothelial cells and development of new capillary vessels during wound repair is dependent on not only the cells and cytokines present but also the production and organization of ECM components both in granulation tissue and in endothelial basement membrane. The ECM regulates angiogenesis by providing scaffold support and signaling roles. They also serve as a reservoir and modulator for growth factors. Laminins are the major noncollagenous ECM of endothelial basement membrane. Two newly recognized laminins, 8 and 10, are the major laminins produced by human dermal microvascular endothelial cells. Laminin 10 is highly expressed in blood vessels around skin wounds. Laminin 8 promotes dermal endothelial cell attachment, migration, and tubule formation. Integrins with either beta 1 or alpha v subunits are the major cellular surface receptors for ECM molecules and mediate the interactions between cells and ECM during wound angiogenesis.

Cytokines↗

PubMed2003

Birth of healthy children after preimplantation diagnosis of beta-thalassemia by whole-genome amplification.

Preimplantation genetic diagnosis (PGD) offers couples at risk for transmitting an inherited disorder the possibility to avoid the need to terminate affected pregnancies. PGD for monogenic diseases is most commonly accomplished by blastomere biopsy from cleavage-stage embryos, followed by PCR-based DNA analysis. However, the molecular heterogeneity of many monogenic diseases requires a diagnostic strategy capable of detecting a range of mutations and compound genotypes. With the above considerations, we developed an accurate and reliable strategy for analysis of beta-globin gene mutations, applicable for PGD for the wide spectrum of beta-thalassemia major mutations in the Chinese population. The strategy involves primer-extension preamplification (PEP), followed by nested PCR and reverse dot blot (RDB) for mutation detection since it facilitates simultaneous analysis of more than one mutation in a single cell. This report describes the application of the strategy in two clinical IVF/PGD cycles at risk for transmitting beta-thalassemia major, which resulted in the first thalassemia-free children born after PGD in China.

Adult↗

PubMed2003

A general model for amyloid fibril assembly based on morphological studies using atomic force microscopy.

Based on atomic force microscopy analysis of the morphology of fibrillar species formed during fibrillation of alpha-synuclein, insulin, and the B1 domain of protein G, a previously described model for the assembly of amyloid fibrils of immunoglobulin light-chain variable domains is proposed as a general model for the assembly of protein fibrils. For all of the proteins studied, we observed two or three fibrillar species that vary in diameter. The smallest, protofilaments, have a uniform height, whereas the larger species, protofibrils and fibrils, have morphologies that are indicative of multiple protofilaments intertwining. In all cases, protofilaments intertwine to form protofibrils, and protofibrils intertwine to form fibrils. We propose that the hierarchical assembly model describes a general mechanism of assembly for all amyloid fibrils.

Amyloid↗

PubMed2003

The TNF2 allele is a risk factor to severe aplastic anemia independent of HLA-DR.

Severe aplastic anemia (SAA) is a disease with an autoimmune component. The susceptibility to the development of SAA is strongly associated with genes in the major histocompatibility complex (MHC). The gene for tumor necrosis factor-alpha (TNF-alpha) is encoded in the MHC locus and TNF-alpha is involved in the pathogenesis of SAA. A TNF-alpha variant with a polymorphism at position -308 in its promoter region (-308A), which is designated TNF2, has been demonstrated to be linked to a number of autoimmune diseases. In this study, the TNF-alpha -308 promoter polymorphism and HLA-DRB1 alleles were analyzed in 75 SAA patients, 55 mild aplastic anemia patients (MAA), and 128 controls. In SAA the phenotype frequencies of TNF2, HLA-DR3, and -DR2 were significantly higher in comparison to controls. Stratification analysis confirmed that the TNF2 allele contributes to the susceptibility to SAA independently of HLA-DR3 or -DR2. The results indicated that TNF2 might act as an independent risk factor for SAA.

Adolescent↗

PubMed2003

The heparan sulfate proteoglycan gene polymorphism: association with type 2 diabetic nephropathy in Chinese.

The objective of this study was to investigate the association between the heparan sulfate proteoglycan (HSPG) gene G/T polymorphism and diabetic nephropathy in type 2 diabetes in Chinese. The HSPG gene polymorphism (G/T) was determined using polymerase chain reaction - restriction fragment length polymorphism (PCR-RFLP) in 290 Chinese type 2 diabetes mellitus patients comprising 77 cases without nephropathy and 213 cases with nephropathy with either proteinuria (163) or renal insufficiency (50) and a control group of 190 non-diabetics. A significant increase in the frequencies of the T allele and TT + TG genotype was observed in subjects with diabetic renal insufficiency as compared with diabetic subjects without nephropathy and those with diabetic proteinuria (for the T allele: Fisher's two-tailed exact p was 0.015 and 0.002, respectively; for the TT + TG genotype; both p values were < 0.001). Diabetic subjects without nephropathy and those with albuminuria carrying the T allele had odds ratios for the development of renal insufficiency of 1.92 (95% CI, 1.12-3.30) and 2.09 (95% CI, 1.29-3.38), respectively, as compared to non-carriers. The T allele of the HSPG gene BamHI polymorphism located in intron 6 may be a risk factor for the development of renal insufficiency in type 2 diabetes mellitus for Chinese.

Aged↗

PubMed2003

Co-inheritance of specific genotypes of HSPG and ApoE gene increases risk of type 2 diabetic nephropathy.

The objective of this paper is to investigate co-inheritance of specific HSPG and ApoE genotypes in the development of Chinese type 2 diabetic nephropathy. PCR-RFLP was used to detect HSPG and ApoE genotypes in 385 Chinese subjects including 298 patients with type 2 diabetes mellitus (T2DM) and 87 non-diabetic controls (Non-DM). The T2DM group was subdivided into patients with (TDN; n = 218) and without diabetic nephropathy (Non-DN; n = 80). The latter group was further subdivided into groups of patients with microalbuminuria nephropathy (DN-1; n = 129) and severe diabetic nephropathy (DN-2; n = 89). We then compared the relative frequencies of various HSPG and ApoE genotypes and alleles among the groups, searching for predictive trends. The T allele of the HSPG gene occurred more frequently in the DN-2 group than in the Non-DN or DN-1 groups, their Fisher's exact p was 1.05 x 10(-3) and 6.58 x 10(-6); odds ratios were 2.09 (95% CI 1.32-3.30) and 2.48 (95% CI 1.64-3.74), respectively. The E2 allele of the ApoE gene occurred more frequently in the T2DM than in the Non-DM group, the Fisher's exact p was 0.0087; odds ratio was 3.45 (95% CI 1.30-9.81). Genotype analysis showed that the TT or TG of HSPG gene were paired with the E2/2 or E2/3 of ApoE gene significantly more frequently in the TDN group than in the Non-DN group, with an odds ratio of 3.03 (95% CI 1.03-8.90). There was no significant differences in other combinations of genotypes in HSPG and ApoE genes between TDN and Non-DN group. These results suggest that the HSPG T allele is a risk factor for the development of severe diabetic nephropathy in type 2 diabetic patients, and that the ApoE E2 allele is a risk factor for the occurrence of type 2 diabetes mellitus in Chinese general population. In addition, we find that co-inheritance of T/E2 confers a higher risk of type 2 diabetes mellitus progression to diabetic nephropathy in Chinese.

Aged↗

PubMed2003

Alcohol-induced adipogenesis in bone and marrow: a possible mechanism for osteonecrosis.

The effect of alcohol on rabbit bone marrow and on the differentiation of mouse bone marrow stromal cells was investigated. Alcohol was administered intragastrically at a dose of 10 mL/kg/day for 1 to 6 months. Alcohol induced a significant increase in serum lipid peroxides, triglyceride, and cholesterol, and a reduction in superoxide dismutase activity. Fatty infiltration in the liver and adipogenesis in bone marrow were found histologically after alcohol administration. Fat cell hypertrophy and proliferation and diminished hematopoiesis in the subchondral area of the femoral head were observed. Triglycerides were deposited in osteocytes, which became pyknotic, and the percentage of empty osteocyte lacunae increased. None of these abnormal changes were detectable in the control group. In the in vitro study, the marrow stromal cells were treated with increasing (0.03, 0.09, and 0.15 mol/L) concentrations of ethanol for 4 to 21 days. Alcohol induced the differentiation of the cells into adipocytes. The number of adipocytes increased with longer durations of exposure to ethanol and with higher concentrations. Cells treated with ethanol also showed diminished alkaline phosphatase activity and expression of osteocalcin. These novel findings indicate that alcohol can directly induce adipogenesis, decrease osteogenesis in bone marrow stroma, and produce intracellular lipid deposits resulting in the death of osteocytes, which may be associated with the development of osteonecrosis, especially in patients with long-term and excessive use of alcohol.

Adipocytes↗

PubMed2003

Inhibition of platelet adherence to brain microvasculature protects against severe Plasmodium berghei malaria.

Some patients with Plasmodium falciparum infections develop cerebral malaria, acute respiratory distress, and shock and ultimately die even though drug therapy has eliminated the parasite from the blood, suggesting that a systemic inflammatory response contributes to malarial pathogenesis. Plasmodium berghei-infected mice are a well-recognized model of severe malaria (experimental severe malaria [ESM]), and infected mice exhibit a systemic inflammatory response. Because platelets are proposed to contribute to ESM and other systemic inflammatory responses, we determined whether platelet adherence contributes to experimental malarial pathogenesis. Indeed, a significant (P < 0.005) increase in the number of rolling and adherent platelets was observed by intravital microscopy in brain venules of P. berghei-infected mice compared with the number in uninfected controls. P-selectin- or ICAM-1-deficient mice exhibit increased survival after P. berghei infection. We observed a significant (P < 0.0001) reduction in the morbidity of mice injected with anti-CD41 (alpha(IIb) or gpIIb) monoclonal antibody on day 1 of P. berghei infection compared with the morbidity of infected controls injected with rat immunoglobulin G. Additionally, platelet rolling and adhesion in brain venules were reduced in P. berghei mice lacking either P-selectin or ICAM-1 or when the platelets were coated with anti-CD41 monoclonal antibody. Unlike other inflammatory conditions, we did not detect platelet-leukocyte interactions during P. berghei malaria. Because (i). leukocyte adhesion is not markedly altered in the absence of P-selectin or ICAM-1 and (ii). CD41 is not an adhesion molecule for parasitized erythrocytes, these findings support the hypothesis that inhibition of platelet adhesion to the brain microvasculature protects against development of malarial pathogenesis.

Animals↗

PubMed2003

P-selectin contributes to severe experimental malaria but is not required for leukocyte adhesion to brain microvasculature.

Plasmodium berghei-infected mice, a well-recognized model of experimental cerebral malaria (ECM), exhibit many of the hallmarks of a systemic inflammatory response, with organ damage in brain, lung, and kidneys. Identification of the molecules mediating pathogenesis of the inflammatory response, such as leukocyte adhesion, may lead to new therapies. Indeed, mice lacking the cell adhesion molecule P-selectin were significantly (P = 0.005) protected from death due to P. berghei malaria compared with C57BL/6 controls despite similar parasitemia (P = 0.6) being found in both groups of mice. P-selectin levels assessed by the quantitative dual radiolabeled monoclonal antibody technique increased significantly (P < 0.05) in several organs in C57BL/6 mice infected with P. berghei, supporting the concept of a systemic inflammatory response mediating malarial pathogenesis. Intravital microscopic analysis of the brain microvasculature demonstrated significant (P < 0.001) leukocyte rolling and adhesion in brain venules of P. berghei-infected mice compared with those found in uninfected controls. The maximum leukocyte adhesion occurred on day 6 of P. berghei infection, when the mice become moribund and exhibit marked vascular leakage into the brain, lung, and heart. However, P-selectin levels were significantly (P < 0.005) increased in brain, lung, and kidneys during P. berghei malaria in ECM-resistant BALB/c mice compared with those found in uninfected BALB/c controls, indicating that increased P-selectin alone is not sufficient to mediate malarial pathogenesis. Leukocyte adhesion to brain microvessels of P-selectin-deficient mice with P. berghei malaria was similar to that observed in control mice. Collectively, these results indicate that P-selectin is important for the development of malarial pathogenesis but is not required for leukocyte adhesion in brain.

Animals↗