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Biomedical subjects

Gang Lu

Publications and source records attributed to Gang Lu.

At least 37 records · Page 2Linked to original sources
PubMed2005

p38 MAP kinase inhibition enables proliferation of adult mammalian cardiomyocytes.

Adult mammalian cardiomyocytes are considered terminally differentiated and incapable of proliferation. Consequently, acutely injured mammalian hearts do not regenerate, they scar. Here, we show that adult mammalian cardiomyocytes can divide. One important mechanism used by mammalian cardiomyocytes to control cell cycle is p38 MAP kinase activity. p38 regulates expression of genes required for mitosis in cardiomyocytes, including cyclin A and cyclin B. p38 activity is inversely correlated with cardiac growth during development, and its overexpression blocks fetal cardiomyocyte proliferation. Activation of p38 in vivo by MKK3bE reduces BrdU incorporation in fetal cardiomyocytes by 17.6%. In contrast, cardiac-specific p38alpha knockout mice show a 92.3% increase in neonatal cardiomyocyte mitoses. Furthermore, inhibition of p38 in adult cardiomyocytes promotes cytokinesis. Finally, mitosis in adult cardiomyocytes is associated with transient dedifferentiation of the contractile apparatus. Our findings establish p38 as a key negative regulator of cardiomyocyte proliferation and indicate that adult cardiomyocytes can divide.

Animals↗
PubMed2005

p38 MAP kinase mediates inflammatory cytokine induction in cardiomyocytes and extracellular matrix remodeling in heart.

BACKGROUND: Increasing evidence suggests that development of heart failure involves activation of stress-response inflammatory cytokines, including tumor necrosis factor-alpha and interleukin-6. Yet, the myocyte contribution to their induction in failing hearts and the underlying regulatory mechanism in stressed myocardium remain unclear. METHODS AND RESULTS: In cultured cardiac myocytes, specific activation of stress-activated mitogen-activated protein kinase, p38, by upstream activator MKK6bE led to significant induction of tumor necrosis factor-alpha and interleukin-6 secretion, whereas treating cells with a selective p38 inhibitor (SB239068) significantly blocked the cytokine secretion from myocytes and increased their intracellular accumulation. Targeted expression of MKK6bE in transgenic hearts also resulted in a marked elevation in plasma tumor necrosis factor-alpha and interleukin-6; oral administration of SB239068 resulted in a significant reduction in their plasma levels but an increase in intracardiac accumulation of both cytokines. MKK6bE transgenic hearts developed marked interstitial fibrosis with increased matrix metalloproteinase abundance and selective induction of tissue inhibitor of matrix metalloproteinase-1; this extracellular matrix remodeling was also significantly attenuated by p38 inhibition. Along with cytokine induction and extracellular remodeling, MKK6bE transgenic animals displayed impaired hemodynamic function, whereas p38 inhibition improved the cardiac performance and prolonged the survival of the animals. CONCLUSIONS: Stress-activated p38 kinase is a critical regulator of inflammatory response in cardiomyocytes with significant contribution to pathological remodeling in stressed myocardium. Inhibition of p38 may represent a useful therapeutic avenue to ameliorate cardiac pathology and heart failure evolution.

Animals↗
PubMed2005

Hydrogen embrittlement of aluminum: the crucial role of vacancies.

We report first-principles calculations which demonstrate that vacancies can combine with hydrogen impurities in bulk aluminum and play a crucial role in the embrittlement of this prototypical ductile solid. Our studies of hydrogen-induced vacancy superabundant formation and vacancy clusterization in aluminum lead to the conclusion that a large number of H atoms (up to 12) can be trapped at a single vacancy, which overcompensates the energy cost to form the defect. In the presence of trapped H atoms, three nearest-neighbor single vacancies which normally would repel each other, aggregate to form a trivacancy on the slip plane of Al, acting as embryos for microvoids and cracks and resulting in ductile rupture along these planes.

Journal Article↗
PubMed2005

Novel role for cyclin-dependent kinase 2 in neuregulin-induced acetylcholine receptor epsilon subunit expression in differentiated myotubes.

Cyclin-dependent kinases (CDKs) are a family of evolutionarily conserved serine/threonine kinases. CDK2 acts as a checkpoint for the G(1)/S transition in the cell cycle. Despite a down-regulation of CDK2 activity in postmitotic cells, many cell types, including muscle cells, maintain abundant levels of CDK2 protein. This led us to hypothesize that CDK2 may have a function in postmitotic cells. We show here for the first time that CDK2 can be activated by neuregulin (NRG) in differentiated C2C12 myotubes. In addition, this activity is required for expression of the acetylcholine receptor (AChR) epsilon subunit. The switch from the fetal AChRgamma subunit to the adult-type AChRepsilon is required for synapse maturation and the neuromuscular junction. Inhibition of CDK2 activity with either the specific CDK2 inhibitory peptide Tat-LFG or by RNA interference abolished neuregulin-induced AChRepsilon expression. Neuregulin-induced activation of CDK2 also depended on the ErbB receptor, MAPK, and PI3K, all of which have previously been shown to be required for AChRepsilon expression. Neuregulin regulated CDK2 activity through coordinating phosphorylation of CDK2 on Thr-160, accumulation of CDK2 in the nucleus, and down-regulation of the CDK2 inhibitory protein p27 in the nucleus. In addition, we also observed a novel mechanism of regulation of CDK2 activity by a low molecular weight variant of cyclin E in response to NRG. These findings establish CDK2 as an intermediate molecule that integrates NRG-activated signals from both the MAPK and PI3K pathways to AChRepsilon expression and reveal an undiscovered physiological role for CDK2 in postmitotic cells.

Animals↗
PubMed2005

Layer-by-layer assembly of human serum albumin and phospholipid nanotubes based on a template.

The preparation of nanotubes from human serum albumin (HSA) and mixtures of L-alpha-dimyristoylphosphatidic acid (DMPA)/HSA is described. The nanotubes were prepared via alternate adsorption of HSA of different/opposite charges (by variation of the pH) or by sequential adsorption of DMPA and HSA, respectively, onto the inner surfaces of porous anodic alumina templates. This simple layer-by-layer assembly results in a monodisperse size distribution and a uniform orientation. The nanotubes allow the specific incorporation of lipophilic components such as channels or receptors and may thus serve as probes or sensors for biological systems.

Circular Dichroism↗
PubMed2005

Adiponectin inhibits cell proliferation by interacting with several growth factors in an oligomerization-dependent manner.

Adiponectin, an adipocyte-specific secretory protein, is present in serum as three oligomeric complexes. Apart from its roles as an anti-diabetic and anti-atherogenic hormone, adiponectin has been implicated as an important regulator of cell growth and tissue remodeling. Here we show that some of these functions might be mediated by the specific interactions of adiponectin with several important growth factors. Among six different growth factors examined, adiponectin was found to bind with platelet-derived growth factor BB (PDGF-BB), basic fibroblast growth factor (FGF), and heparin-binding epidermal growth factor-like growth factor (HB EGF) with distinct affinities. The bindings of adiponectin with these growth factors are oligomerization-dependent. PDGF-BB bound to the high molecular weight (HMW) and middle molecular weight (MMW) complexes, but not to the low molecular weight (LMW) complex of adiponectin. Basic FGF preferentially interacted with the HMW form, whereas HB EGF bound to all three forms with comparable affinities. These three growth factors did not compete with each other for their bindings to adiponectin, suggesting the involvement of distinct binding sites. The interactions of adiponectin with PDGF-BB, basic FGF, and HB EGF precluded the bindings to their respective membrane receptors and attenuated the DNA synthesis and cell proliferation induced by these growth factors. Small interfering RNA-mediated down-regulation of adiponectin receptors did not affect the suppressive effects of adiponectin on cell proliferation stimulated by these growth factors. These data collectively suggest that the oligomeric complexes of adiponectin can modulate the biological actions of several growth factors by controlling their bioavailability at a pre-receptor level and that this effect might partly account for the anti-atherogenic, anti-angiogenic, and anti-proliferative functions of adiponectin.

Adiponectin↗
PubMed2005

TRPV1b, a functional human vanilloid receptor splice variant.

Transient receptor potential (TRP) genes encode a family of related ion-channel subunits. This family consists of cation-selective, calcium-permeable channels that include a group of vanilloid receptor channels (TRPV) implicated in pain and inflammation. These channels are activated by diverse stimuli, including capsaicin, lipids, membrane deformation, heat, and protons. Six members of the TRPV family have been identified that differ predominantly in their activation properties. However, in neurons, TRPV channels do not account for the observed diversity of responses to activators. By probing human and rat brain cDNA libraries to identify TRPV subunits, we identified a novel human TRPV1 RNA splice variant, TRPV1b, which forms functional ion channels that are activated by temperature (threshold, approximately 47 degrees C), but not by capsaicin or protons. Channels with similar activation properties were found in trigeminal ganglion neurons, suggesting that TRPV1b receptors are expressed in these cells and contribute to thermal nociception.

Amino Acid Sequence↗
PubMed2005

A fMRI study of age-related differential cortical patterns during cued motor movement.

Healthy adults of three age groups (young, middle-age and older) were cued by a multimedia projector to perform a series of simple (making a fist, opening/closing of the mouth) and complex (opposition of index finger and thumb, chewing gum) motor tasks while being scanned by functional magnetic resonance imaging. Our results showed that in unilateral hand movements, the premotor/motor cortex in the contralateral hemisphere was most strongly activated. Supplementary motor cortex involvement was usually present in the young and not in the old, except in precision movement when supplementary motor cortex was also involved in the old. For movements of the face (chewing, opening and closing of mouth), the prefrontal cortex was activated in the old age group but finger and hand movements never activated the prefrontal cortex in any age. Furthermore, areas like insula and cingulate gyrus might be activated in motor tasks. We conclude that different motor activities triggered diverse activation patterns which differed in different age groups.

Adult↗
PubMed2005

Carbon nanotube interaction with DNA.

We investigate a system consisting of B-DNA and an array of (10,0) carbon nanotubes periodically arranged to fit into the major groove of the DNA. We obtain an accurate electronic structure of the combined system, which reveals that it is semiconducting and that the bands on either end of the gap are derived exclusively from one of the two components. We discuss in detail how this system can be used as either an electronic switch involving transport through both components, or as a device for ultrafast DNA sequencing.

Computer Simulation↗
PubMed2005

Postmortem changes in the central nervous system and adrenal medulla of the heroin addicts.

This study describes the pathological changes in 20 heroin addicts (12 male and 8 female) autopsied 24 h after sudden death. The central nervous system (including the pituitary body) and the adrenal medulla were studied, along with those from age-matched controls who died from traffic accidents. Immunohistochemistry and histological (Hematoxylin and eosin) observation were performed. Some neuronal cells in every region of the CNS were positive for opioid receptors but these cells were most numerous in the hippocampus. Positive opioid fibers were most abundant in the basal ganglia region. Histopathology indicated coagulative changes of cytoplasm and dissolution of Nissl bodies of neuron. Edema of nerve fibers was frequently demonstrated. Pituitary body showed an evident decrease or even absence of basophils in the pars anterior. The adrenal medulla featured a down regulation of chromaffin granules. Degeneration of CNS neurons and fibers, alterations in hormonal and blood pressure regulation therefore would be the prime targets of heroin addiction in human subjects.

Adrenal Medulla↗
PubMed2005

ANOSVA: a statistical method for detecting splice variation from expression data.

MOTIVATION: Many or most mammalian genes undergo alternative splicing, generating a variety of transcripts from a single gene. New information on splice variation is becoming available through technology for measuring expression levels of several exons or splice junctions per gene. We have developed a statistical method, ANalysis Of Splice VAriation (ANOSVA) to detect alternative splicing from expression data. Since ANOSVA requires no transcript information, it can be applied when the level of annotation is poor. When validated against spiked clone data, it generated no false positives and few false negatives. We demonstrated ANOSVA with data from a prototype mouse alternative splicing array, run against normal adult tissues, yielding a set of genes with evidence of tissue-specific splice variation. AVAILABILITY: The results are available at the supplementary information site. SUPPLEMENTARY INFORMATION: The results are available at the supplementary information site https://bioinfo.affymetrix.com/Papers/ANOSVA/

Alternative Splicing↗
PubMed2005

bcl2, bax, and nestin in the brains of patients with neurodegeneration and those of normal aging.

This study was conducted by employing specimens from the frontal cortices of Alzheimer, multiple-infarct dementia patients, and those of normal aging (age matched to patients). The objective was to evaluate and compare the bcl2, bax, and nestin patterns in these three groups. Using immunocytochemistry, it was observed that bcl2 and bax active sites were colocalized in 45% of cells in Alzheimer, 52% of cells in multiple infarct, and 30% of cells in normal aging. bcl2 and bax could also be separately located in cells of all three groups. bax cells were most prominent in number in Alzheimer patients and least prominent in normal aging. nestin was found in all three groups but was most prominent in the multiple-infarct patients. Both astrocytes and neurons demonstrated positive nestin sites. The difference in pattern between groups will lead to further understanding of cellular changes in neurodegenerative patients and those of normal aging.

Aged↗
PubMed2005

[Effects of adipose tissue extract on rat skin regeneration in vitro].

OBJECTIVE: To investigate the effects of adipose tissue extract on growth of rat skin in vitro. METHODS: Neonatal rat skin (area of 2 mm x 2 mm) was cultured in Dulbecco's modified Eagle's medium (DMEM) containing 10% adipose tissue extract and 10% phosphate buffered solution (PBS). After being cultured for 6 days, the area of skin was measured. RESULTS: Skin in both groups grew in area. With the addition of adipose tissue extract, the skin measured (8.43+/-1.40) mm2 in area after 6 days, and it was approximately 2 times of that of PBS group, in which the skin area was (4.18+/-1.11) mm2. The difference was statistically significant (P<0.05). CONCLUSION: Adipose tissue extract promote skin growth, which may be attributed to the presence of some growth factors in the extract.

Adipose Tissue↗
PubMed2005

[Effects of neural stem cells transplantation on glial cell line-derived neurotrophic factor and growth associated protein 43 after spinal cord injury in rats].

OBJECTIVE: To observe the effects of neural stem cells(NSCs) transplantation on the glial cell line-derived neurotrophic factor (GDNF) and growth associated protein 43(GAP-43) after the spinal cord injury (SCI), and to investigate the mechanism of repairing the SCI by NSCs transplantation. METHODS: The neural stem cells from the hippocampus of rats' embryo were cultured and identified by immunocytochemistry. The SCI model was made by the modified Allen device. Sixty adult Wistar rats were randomly divided into three groups: spinal cord injury was treated with transplantation of NSCs (group A, n = 24), with DMEM solution (group B, n = 24) and normal control group without being injured(group C, n = 12). Seven days after the operation of SCI, the NSCs were transplanted into the injured site. Then GAP-43 and GDNF expressions were tested by RT-PCR and immunohistochemistry. RESULTS: Compared with group B, the GDNF mRNA expression of group A increased by 23.3% on the 1st day, by 26.8% on the 3rd day and by 32.7% on the 7th day; the GAP-43 mRNA expression increased by 19.5% on the 1st day, 21.6% on the 3rd day and 23.1% on the 7th day. There were statistically significant differences (P<0.05). CONCLUSION: The transplantation of NSCs can change the micro-environment injured site and promote the regeneration of axon by enhancing the expressions of GDNF mRNA and GAP-43 mRNA. It is one of the mechanisms of repairing the SCI by NSCs transplantation.

Animals↗
PubMed2005

[Bio-inductive effects of inorganic elements on skin wound healing].

OBJECTIVE: To explore the bio-inductive effects of inorganic elements (Dermlin) on the human epithelial proliferation and differentiation and their promoting effects on skin wound healing. METHODS: 1 ). Cellular test: Normal human skin epithelial cells were cultured with 20 g/L Dermlin supplemented culture medium (E group) and regular culture medium (C group), respectively. The cell proliferation rate and the expressions of type IV collagen and epidermal growth factor (EGF) in the supernatant were determined in 12 and 20 post culture days (PCD). (2). Animal test: Self-consubstantiality control was employed in the study. Sixty Sprague - Dawley rats were inflicted with two symmetric 10% TBSA of superficial or deep partial thickness scald on the back of each rat, and were divided into control[ C, with topical application of silver sulfadiazine (SD - Ag) cream to the wounds] and treatment (T, with 1 g/100 cm2 Dermlin topical application to the wounds) groups. The pathological changes in wound skin were observed and the wound healing rate was calculated on 3, 5, 7, 10, 14 and 18 post treatment day (PTD). (3). Randomized, double-blinded and consubstantiality control method was employed in the clinical trial. Ninety patients were enrolled in the clinical study, among them 30 cases with 60 donor site wounds, 30 with 60 superficial and 30 with 60 deep partial thickness burn wounds were included. Dermlin in dose of 1 g/100 cm2 was applied to the wounds in T group and SD - Ag cream in C group for up to 18 days. Furthermore, sixty patients with diabetic foot ulcers were included for 1 g/100 cm2 Dermlin treatment. The wound healing rate was observed. And the blood and urine test and the indices of hepatic and renal function were determined. RESULTS: 1). Cellular test: The cell proliferation rate and the expression of type IV collagen and EGF in the culture supernatant were obviously higher than those in control group at the same time points (P < 0.01). 2). Animal test: Hyperplastic granulation tissue occurred in the rat wound in the T group since 5 PTD, while that occurred in the C group since 7 PTD. The healing rate of superficial thickness wound in T group on 7, 10, 14 PTD, and that of deep partial thickness wound in T group on 5, 10, 18 PTD were obviously higher than that in the C group (P <0.05). 3). Clinical study indicated that the wound healing rate of the patients with superficial or deep partial thickness scald in the T group was evidently higher than that in the C group on 5 and 10 PTD (P <0.05), but the wound healing time of the superficial, deep partial thickness wound and donor site wound in the T group was significantly shorter than that in the C group (P < 0.05). Before treatment, the square of the ulcers on the foot of the patients with diabetic was (39 +/- 28) cm2, and it was reduced to (19 +/- 23) cm2 2 weeks later, with the therapeutic efficacy reaching 62.5% . For all patients, no obvious change was found in the blood test and hepatic and renal function indices. CONCLUSION: The inorganic element (Dermlin) is beneficial to wound healing and to the proliferation and differentiation of epithelial cells.

Adolescent↗
PubMed2004

Self-assembly of human serum albumin (HSA) and L-alpha-dimyristoylphosphatidic acid (DMPA) microcapsules for controlled drug release.

Human serum albumin (HSA) and L-alpha-dimyristoylphosphatidic acid (DMPA) were applied as a pair to encapsulate ibuprofen microcrystals by means of a technique based on the layer-by-layer (LbL) assembly of oppositely charged species, for the purpose of controlling drug release. The successful adsorption of HSA and DMPA multilayers onto ibuprofen crystals was confirmed by optical microscopy. The drug release process, in a solution of pH 7.4, was monitored by optical microscopy and UV spectroscopy. The results revealed that the rate of release of ibuprofen from HSA/DMPA microcapsules decreased as the capsule wall thickness and drug crystal size increased, indicating that the permeability of the microcapsules can be controlled by simply varying the number of HSA/DMPA deposition cycles.

Capsules↗
PubMed2004

Silicate complexes of sugars in aqueous solution.

Certain sugars react readily with basic silicic acid to form soluble 2/1 (sugar/silicic acid) silicate complexes. Failure of monohydroxy compounds to give soluble products under these conditions indicates that the sugar silicates are chelates: five-membered diolato rings. Only furanose forms react. Pyranose sugars are stable under these conditions. Because all glycosides fail to react with silicic acid under these conditions, reaction appears to involve the anomeric position (C1 in aldoses, C2 in ketoses), which has a more acidic hydroxy group. Reaction is completed only when the anomeric hydroxy group is cis to an adjacent hydroxy group. The appropriate furanose form must have sufficient natural abundance and solubility to provide an observable product, as measured by (29)Si and (13)C NMR spectroscopy. These structural and practical constraints rationalize the successful reaction of the monosaccharides ribose, xylose, lyxose, talose, psicose, fructose, sorbose, and tagatose and the disaccharides lactulose, maltulose, and palatinose. Glucose, mannose, galactose, and sucrose, among others, failed to form complexes. This high selectivity for formation of sugar silicates may have ramifications in prebiotic chemistry.

Carbohydrate Conformation↗