Biomedical subjects

Yan Pan

Publications and source records attributed to Yan Pan.

At least 19 recordsLinked to original sources

PubMed2007

Motor neuron degeneration in amyotrophic lateral sclerosis mutant superoxide dismutase-1 transgenic mice: mechanisms of mitochondriopathy and cell death.

The mechanisms of human mutant superoxide dismutase-1 (mSOD1) toxicity to motor neurons (MNs) are unresolved. We show that MNs in G93A-mSOD1 transgenic mice undergo slow degeneration lacking similarity to apoptosis structurally and biochemically. It is characterized by somal and mitochondrial swelling and formation of DNA single-strand breaks prior to double-strand breaks occurring in nuclear and mitochondrial DNA. p53 and p73 are activated in degenerating MNs, but without nuclear import. The MN death is independent of activation of caspases-1, -3, and -8 or apoptosis-inducing factor within MNs, with a blockade of apoptosis possibly mediated by Aven up-regulation. MN swelling is associated with compromised Na,K-ATPase activity and aggregation. mSOD1 mouse MNs accumulate mitochondria from the axon terminals and generate higher levels of superoxide, nitric oxide, and peroxynitrite than MNs in control mice. Nitrated and aggregated cytochrome c oxidase subunit-I and alpha-synuclein as well as nitrated SOD2 accumulate in mSOD1 mouse spinal cord. Mitochondria in mSOD1 mouse MNs accumulate NADPH diaphorase and inducible nitric oxide synthase (iNOS)-like immunoreactivity, and iNOS gene deletion extends significantly the life span of G93A-mSOD1 mice. Prior to MN loss, spinal interneurons degenerate. These results identify novel mechanisms for mitochondriopathy and MN degeneration in amyotrophic lateral sclerosis (ALS) mice involving blockade of apoptosis, accumulation of MN mitochondria with enhanced toxic potential from distal terminals, NOS localization in MN mitochondria and peroxynitrite damage, and early degeneration of alpha-synuclein(+) interneurons. The data support roles for oxidative stress, protein nitration and aggregation, and excitotoxicity as participants in the process of MN degeneration caused by mSOD1.

Age Factors↗

PubMed2006

Synthesis, protein levels, activity, and phosphorylation state of tyrosine hydroxylase in mesoaccumbens and nigrostriatal dopamine pathways of chronically food-restricted rats.

Chronic food restriction (FR) enhances the rewarding and motor-activating effects of abused drugs, and is accompanied by changes in dopamine (DA) dynamics and increased D-1 DA receptor-mediated cell signaling and transcriptional responses in nucleus accumbens (NAc). However, little is known about effects of FR on DA synthetic activity in the mesoaccumbens and nigrostriatal pathways. In Experiment 1 of the present study, tyrosine hydroxylase (TH) gene expression was measured in ventral tegmental area and substantia nigra, using real-time RT-PCR and in situ hybridization; no differences were observed between FR and ad libitum fed (AL) rats. In Experiment 2, TH protein levels, determined by Western blot, were found to be elevated in NAc and caudate-putamen (CPu) of FR relative to AL rats. In the absence of increased transcription, this may reflect a slowing of TH degradation. In Experiments 3 and 4, DA synthetic activity was assessed by Western blot measurement of TH phosphorylation at Ser40, and HPLC measurement of in vivo tyrosine hydroxylation rate, as reflected by DOPA accumulation following administration of a decarboxylase inhibitor (NSD-1015; 100 mg/kg, i.p.). Basal phospho-(Ser40)-TH levels did not differ between groups but DOPA accumulation was decreased by FR. Decreased DOPA synthesis, despite increased levels of TH protein, may reflect the inhibitory effect of increased DA binding to TH protein or decreased concentrations of cofactor tetrahydrobiopterin. Finally, in response to D-amphetamine (0.5 and 5.0 mg/kg, i.p.), phospho-(Ser40)-TH was selectively decreased in NAc of FR rats. This suggests increased feedback inhibition of DA synthesis-a possible consequence of postsynaptic receptor hypersensitivity, or increased extracellular DA concentration. These results indicate that FR increases TH protein levels, but may decrease the capacity for DA synthesis by decreasing TH activity. According to this scheme, the previously observed upregulation of striatal cell signaling and transcriptional responses to DA receptor agonist administration may include compensatory neuroadaptations.

Analysis of Variance↗

PubMed2006

Reduction in the in vitro expression of Brain-Pancreas Relative Protein by oxygen and glucose-deprivation.

Brain-Pancreas Relative Protein (BPRP) is a novel protein found in our laboratory. In previous study we observed a significant reduction in BPRP in ischemic brain of rat. Here we undertook this study to explore the possible mediating mechanism by which oxygen and glucose-deprivation culture (OGD), a model of ischemia in vitro, decreased the expression of BPRP in PC12 cells. BPRP was found to be expressed in PC12 cells and OGD caused a significant reduction in BPRP expression. The effect of OGD was primarily mediated by reactive oxygen species (ROS) because OGD upregulated the production of ROS and the inhibitors of protein kinase C, calmodulin, free radical scavengers reduced OGD-induced ROS production, while increased the expression of BPRP in PC12 cells. These data indicate that OGD decreases the expression of BPRP via enhanced formation of intracellular ROS.

Animals↗

PubMed2006

Effects of central leptin infusion on the reward-potentiating effect of D-amphetamine.

It was previously reported that chronic food restriction and maintenance of rats at 75-80% of initial body weight enhanced the reward-potentiating effect of D-amphetamine in the lateral hypothalamic self-stimulation (LHSS) paradigm. Moreover, the enhancement reversed in parallel with body weight recovery when ad libitum access to food was reinstated. The present study tested the hypothesis that hypoleptinemia during food restriction is necessary for expression of enhanced drug reward. In Experiment 1, intracerebroventricular (i.c.v.) infusion of leptin (0.5 microg/0.5 microl/hr for 8 days) in food-restricted rats did not alter the rewarding effect of D-amphetamine (0.5 mg/kg, i.p.). Considering that i.c.v. leptin may not diffuse into deep brain regions where direct effects on drug reward sensitivity may be exerted, effects of acute bilateral microinjection of leptin (0.5 microg) in ventral tegmental area and nucleus accumbens were tested in Experiment 2 and found to have no effect. In Experiment 3, chronic i.c.v. leptin infusion in ad libitum fed rats decreased food intake and body weight and enhanced the rewarding effect of D-amphetamine. Sensitivity to D-amphetamine returned to normal as body weight recovered following cessation of leptin infusion. This result suggests that weight loss, whether from hormone-induced appetite suppression or experimenter-imposed food restriction, is sufficient to enhance drug reward sensitivity. Experiment 4 tested whether food restriction in the absence of body weight loss alters drug reward sensitivity. Rats received chronic i.c.v. infusion of the orexigenic melanocortin receptor antagonist, SHU9119 (0.02 microg/0.5 microl/hr for 12 days), and a subset were pair-fed to vehicle-infused controls. Although these subjects ingested approximately 50% of the amount of food ingested by free-feeding SHU9119-infused rats, they displayed no weight loss and no change in sensitivity to D-amphetamine. Together, results of this study support the importance of weight loss, but not leptin, in the enhancement of drug reward sensitivity.

Animals↗

PubMed2006

Cardiac-specific elevations in thyroid hormone enhance contractility and prevent pressure overload-induced cardiac dysfunction.

Thyroid hormone (TH) is critical for cardiac development and heart function. In heart disease, TH metabolism is abnormal, and many biochemical and functional alterations mirror hypothyroidism. Although TH therapy has been advocated for treating heart disease, a clear benefit of TH has yet to be established, possibly because of peripheral actions of TH. To assess the potential efficacy of TH in treating heart disease, type 2 deiodinase (D2), which converts the prohormone thyroxine to active triiodothyronine (T3), was expressed transiently in mouse hearts by using the tetracycline transactivator system. Increased cardiac D2 activity led to elevated cardiac T3 levels and to enhanced myocardial contractility, accompanied by increased Ca(2+) transients and sarcoplasmic reticulum (SR) Ca(2+) uptake. These phenotypic changes were associated with up-regulation of sarco(endo)plasmic reticulum calcium ATPase (SERCA) 2a expression as well as decreased Na(+)/Ca(2+) exchanger, beta-myosin heavy chain, and sarcolipin (SLN) expression. In pressure overload, targeted increases in D2 activity could not block hypertrophy but could completely prevent impaired contractility and SR Ca(2+) cycling as well as altered expression patterns of SERCA2a, SLN, and other markers of pathological hypertrophy. Our results establish that elevated D2 activity in the heart increases T3 levels and enhances cardiac contractile function while preventing deterioration of cardiac function and altered gene expression after pressure overload.

Animals↗

PubMed2006

Parkinson's disease alpha-synuclein transgenic mice develop neuronal mitochondrial degeneration and cell death.

Alpha-synuclein (alpha-Syn) is enriched in nerve terminals. Two mutations in the alpha-Syn gene (Ala53--> Thr and Ala30--> Pro) occur in autosomal dominant familial Parkinson's disease. Mice overexpressing the human A53T mutant alpha-Syn develop a severe movement disorder, paralysis, and synucleinopathy, but the mechanisms are not understood. We examined whether transgenic mice expressing human wild-type or familial Parkinson's disease-linked A53T or A30P mutant alpha-syn develop neuronal degeneration and cell death. Mutant mice were examined at early- to mid-stage disease and at near end-stage disease. Age-matched nontransgenic littermates were controls. In A53T mice, neurons in brainstem and spinal cord exhibited large axonal swellings, somal chromatolytic changes, and nuclear condensation. Spheroid eosinophilic Lewy body-like inclusions were present in the cytoplasm of cortical neurons and spinal motor neurons. These inclusions contained human alpha-syn and nitrated synuclein. Motor neurons were depleted (approximately 75%) in A53T mice but were affected less in A30P mice. Axonal degeneration was present in many regions. Electron microscopy confirmed the cell and axonal degeneration and revealed cytoplasmic inclusions in dendrites and axons. Some inclusions were degenerating mitochondria and were positive for humanalpha-syn. Mitochondrial complex IV and V proteins were at control levels, but complex IV activity was reduced significantly in spinal cord. Subsets of neurons in neocortex, brainstem, and spinal cord ventral horn were positive for terminal deoxynucleotidyl transferase-mediated biotinylated UTP nick end labeling, cleaved caspase-3, and p53. Mitochondria in neurons had terminal deoxynucleotidyl transferase-mediated biotinylated UTP nick end labeling-positive matrices and p53 at the outer membrane. Thus, A53T mutant mice develop intraneuronal inclusions, mitochondrial DNA damage and degeneration, and apoptotic-like death of neocortical, brainstem, and motor neurons.

Alanine↗

PubMed2006

Water channels and zymogen granules in salivary glands.

Salivary secretion occurs in response to stimulation by neurotransmitters released from autonomic nerve endings. The molecular mechanisms underlying the secretion of water, a main component of saliva, from salivary glands are not known; the plasma membrane is a major barrier to water transport. A 28-kDa integral membrane protein, distributed in highly water-permeable tissues, was identified as a water channel protein, aquaporin (AQP). Thirteen AQPs (AQP0 - AQP12) have been identified in mammals. AQP5 is localized in lipid rafts under unstimulated conditions and translocates to the apical plasma membrane in rat parotid glands upon stimulation by muscarinic agonists. The importance of increases in intracellular calcium concentration [Ca(2+)](i) and the nitric oxide synthase and protein kinase G signaling pathway in the translocation of AQP5 is reviewed in section I. Signals generated by the activation of Ca(2+) mobilizing receptors simultaneously trigger and regulate exocytosis. Zymogen granule exocytosis occurs under the control of essential process, stimulus-secretion coupling, in salivary glands. Ca(2+) signaling is a principal signal in both protein and water secretion from salivary glands induced by cholinergic stimulation. On the other hand, the cyclic adenosine monophosphate (cAMP)/cAMP-dependent protein kinase system has a major role in zymogen granule exocytosis without significant increases in [Ca(2+)](i). In section II, the mechanisms underlying the control of salivary protein secretion and its dysfunction are reviewed.

Animals↗

PubMed2005

Coordination frameworks constructed from bipyridyl piperazine and MCl2 (M = Co, Ni, Zn): structural characterization and optical properties.

Three metal-organic polymers, [CoCl2(bpfp)]n 1, {[NiCl2(bpfp)2](H2O)3}n 2 and [ZnCl2(bpfp)]n 3 (bpfp = N,N'-bis(3-pyridylformyl)piperazine), are formed by the self-assembly of the flexible bpfp with MCl2 (M = Co, Ni, Zn), respectively. X-Ray single-crystal structural analysis reveals that polymer 1 exhibits a novel grid network, in which the grid is composed of segments of bpfp and cobalt ions. Polymer 2 consists of 2D rhombohedral grids, the dimensions of the grid are 15.782 x 12.434 A2 and the diagonal-to-diagonal distances are 13.186 x 25.169 A2. In polymer 3, infinite wavelike chains are extended to 2D supramolecular arrays via C-H...Cl hydrogen bonds. The third-order nonlinear optical (NLO) behaviors of 1-3 and bpfp were investigated in dilute DMF solution by Z-scan measurement. The results show that 1, 2 and 3 exhibit good third-order NLO properties, which are quite different from bpfp that shows weak NLO behavior. This paper demonstrates that metal ions can strongly influence the crystal structures and third-order NLO properties of polymers.

2,2'-Dipyridyl↗

PubMed2005

Striatal cell signaling in chronically food-restricted rats under basal conditions and in response to brief handling.

Chronic food restriction increases exploratory behavior, cognitive function, and the rewarding effects of abused drugs. Recently, striatal neuroadaptations that may be involved in these effects were observed. Specifically, D-1 dopamine (DA) receptor agonist challenge produced stronger activation of extracellular signal-regulated kinase (ERK), calcium-calmodulin-dependent kinase II (CaMKII), and the nuclear transcription factor cAMP response element binding protein (CREB) in nucleus accumbens (NAc) of food-restricted (FR) relative to ad libitum fed (AL) rats. Further, when FR rats were injected intracerebroventricularly (i.c.v.) with vehicle (saline) they displayed stronger activation of c-Jun N-terminal protein kinase (JNK), ERK and CaMKII than did AL rats. It is not known to what extent the latter effects represent the basal state of FR rats or an amplified response to the brief handling involved in the i.c.v. injection procedure. Using Western blotting it was found that basal phospho-JNK is higher in caudate-putamen (CPu) and NAc of FR relative to AL rats. Interestingly, brief handling decreased phospho-JNK levels in FR subjects. Basal phospho-ERK1/2 also tended to be elevated in CPu and NAc of FR rats but the elevation was not significant. However, phospho-MEK--the activated kinase upstream of ERK1/2--was significantly elevated in NAc of FR rats. Neither ERK1/2 nor MEK were activated by brief handling. CaMKII was selectively activated by handling in NAc of FR rats, suggesting a state-dependent response to a salient event. Given the established involvement of mitogen-activated protein kinase (MAPK) and CaMKII in synaptic plasticity, learning and memory, the increase in basal phospho-MEK and hyperresponsiveness of CaMKII in NAc may represent adaptive cellular responses to persistent negative energy balance that facilitate associative learning in connection with food-seeking.

Animals↗

PubMed2005

Proteome dynamics during C2C12 myoblast differentiation.

Mouse-derived C2C12 myoblasts serve as an experimentally tractable model system for investigating the molecular basis of skeletal muscle cell specification and development. To examine the biochemical adaptations associated with myocyte formation comprehensively, we used large scale gel-free tandem mass spectrometry to monitor global proteome alterations throughout a time course analysis of the myogenic C2C12 differentiation program. The relative abundance of approximately 1,800 high confidence proteins was tracked across multiple time points using capillary scale multidimensional liquid chromatography coupled to high throughput shotgun sequencing. Hierarchical clustering of the resulting profiles revealed differential waves of expression of proteins linked to intracellular signaling, transcription, cytoarchitecture, adhesion, metabolism, and muscle contraction across the early, mid, and late stages of differentiation. Several hundred previously uncharacterized proteins were likewise detected in a stage-specific manner, suggesting novel roles in myogenesis and/or muscle function. These proteomic data are complementary to recent microarray-based studies of gene expression patterns in developing myotubes and provide a holistic framework for understanding how diverse biochemical processes are coordinated at the cellular level during skeletal muscle development.

Animals↗

PubMed2005

Comparison of the efficacy of 1-day high-dose quadruple therapy versus 7-day triple therapy for treatment of Helicobacter pylori infection.

BACKGROUND: The proton pump inhibitor (PPI)-based 7-day triple therapy is the regimen with the highest cure rates for eradication of Helicobacter pylori infection and has been recommended as the first-line regimen in the world. It had been reported that a 1-day quadruple therapy could also successfully cure 95% of the H. pylori infected patients. OBJECTIVES: To observe the efficacy of 1-day high-dose quadruple therapy versus 7-day triple therapy for treatment of H. pylori infection, and to observe side-effects of the two different regimens. METHODS: This randomized, open, parallel-controlled study was conducted at Renji Hospital between November 2004 to March 2005. A total of 80 consecutive patients with non-ulcer dyspepsia, who were H. pylori positive proven by both rapid urease test and histology were included and randomly assigned to 1-day quadruple therapy or 7-day triple therapy. Thirty-nine patients were administered with 1-day high-dose quadruple therapy including esomeprazole 40 mg b.i.d., colloidal bismuth subcitrate 440 mg q.i.d., amoxicillin 2 g q.i.d. and metronidazole (400 mg q.i.d.) for 1 day. Forty-one patients received a standard 7-day triple therapy consisting of esomeprazole 20 mg b.i.d., clarithromycin 500 mg b.i.d. and amoxicillin 1 g b.i.d. for 7 days. The eradication rates were evaluated by the (13)C-urea breath test at least 4 weeks after completion of a course treatment. RESULTS: Seventy-seven patients completed the trial and three patients dropped out. The eradication rates in the 1-day therapeutic group and the 7-day therapeutic group were 39.5% (15/38) and 84.6% (33/39), respectively. There was a statistically significant difference between the two groups (P < 0.0001). Short-lasting and self-limiting side effects including thirst, a metallic taste, diarrhea and abdominal pain were reported in three patients (7.9%) in the 1-day group and seven patients (18%) in the 7-day group (P = 0.31). CONCLUSIONS: A 1-day high-dose quadruple therapy with amoxicillin, metronidazole, bismuth salt, and esomeprazole is not effective for eradication of H. pylori compared with the standard 7-day triple therapy.

Adult↗

PubMed2005

GLB prevents tumor metastasis of Lewis lung carcinoma by inhibiting tumor adhesion actions.

AIM: To investigate the inhibitory effect of a new compound of GLB on tumor metastasis in vivo and analyze its actions on tumor cell adhesion to clarify its mechanism. METHODS: The effect of GLB on tumor metastasis was analyzed by Lewis lung carcinoma model. The pathological morphology of lung alveolar was evaluated by hematoxylin-eosin staining. The effect of GLB on the proliferation of human prostate cancer cell (PC-3M, with a high metastatic characteristic) was studied using the MTT method, and its actions on PC-3M cell adhesion to human umbilical vein endothelial cells (HUVEC) and laminin were analyzed in vitro. RESULTS: GLB (100 mg/kg/d for 28 d, ig) reduced the number of lung colonies of Lewis lung carcinoma metastasis significantly (P<0.05). Simultaneously, GLB could mitigate the damage of lung alveolar caused by metastasic tumor deposits. In vitro, GLB inhibited dramatically the adhesion of PC-3M cells to HUVEC (P< 0.01) and laminin (P<0.05), without cytotoxic or anti-proliferative action on PC-3M cells. CONCLUSION: GLB has anti-tumor metastatic activity, which partly depends on its inhibition of tumor adhesion.

Animals↗

PubMed2004

Effects of the group I metabotropic glutamate receptor agonist, DHPG, and injection stress on striatal cell signaling in food-restricted and ad libitum fed rats.

BACKGROUND: Chronic food restriction augments the rewarding effect of centrally administered psychostimulant drugs and this effect may involve a previously documented upregulation of D-1 dopamine receptor-mediated MAP kinase signaling in nucleus accumbens (NAc) and caudate-putamen (CPu). Psychostimulants are known to induce striatal glutamate release, and group I metabotropic glutamate receptors (mGluR) have been implicated in the cellular and behavioral responses to amphetamine. The purpose of the present study was to evaluate whether chronic food restriction increases striatal MAP kinase signaling in response to the group I mGluR agonist, DHPG. RESULTS: Western immunoblotting was used to demonstrate that intracerebroventricular (i.c.v.) injection of DHPG (500 nmol) produces greater activation of ERK1/2 and CREB in CPu and NAc of food-restricted as compared to ad libitum fed rats. Fos-immunostaining induced by DHPG was also stronger in CPu and NAc core of food-restricted relative to ad libitum fed rats. However, i.c.v. injection of saline-vehicle produced greater activation of ERK1/2 and CREB in CPu and NAc of food-restricted relative to ad libitum fed rats, and this difference was not seen when subjects received no i.c.v. injection prior to sacrifice. In addition, although DHPG activated Akt, there was no difference in Akt activation between feeding groups. To probe whether the augmented ERK1/2 and CREB activation in vehicle-injected food-restricted rats are mediated by one or more GluR types, effects of an NMDA antagonist (MK-801, 100 nmol), AMPA antagonist (DNQX, 10 nmol), and group I mGluR antagonist (AIDA, 100 nmol) were compared to saline-vehicle. Antagonist injections did not diminish activation of ERK1/2 or CREB. CONCLUSIONS: These results indicate that a group I mGluR agonist induces phosphorylation of Akt, ERK1/2 and CREB in both CPu and NAc. However, group I mGluR-mediated signaling may not be upregulated in food-restricted rats. Rather, a physiological response to "i.c.v. injection stress" is augmented by food restriction and appears to summate with effects of the group I mGluR agonist in activating ERK1/2 and CREB. While the augmented cellular response of food-restricted rats to i.c.v. injection treatment represents additional evidence of enhanced CNS responsiveness in these subjects, the functional significance and underlying mechanism(s) of this effect remain to be elucidated.

Animals↗

PubMed2004

Identification of biochemical adaptations in hyper- or hypocontractile hearts from phospholamban mutant mice by expression proteomics.

Phospholamban (PLN) is a critical regulator of cardiac contractility through its binding to and regulation of the activity of the sarco(endo)plasmic reticulum Ca2+ ATPase. To uncover biochemical adaptations associated with extremes of cardiac muscle contractility, we used high-throughput gel-free tandem MS to monitor differences in the relative abundance of membrane proteins in standard microsomal fractions isolated from the hearts of PLN-null mice (PLN-KO) with high contractility and from transgenic mice overexpressing a superinhibitory PLN mutant in a PLN-null background (I40A-KO) with diminished contractility. Significant differential expression was detected for a subset of the 782 proteins identified, including known membrane-associated biomarkers, components of signaling pathways, and previously uninvestigated proteins. Proteins involved in fat and carbohydrate metabolism and proteins linked to G protein-signaling pathways activating protein kinase C were enriched in I40A-KO cardiac muscle, whereas proteins linked to enhanced contractile function were enriched in PLN-KO mutant hearts. These data demonstrate that Ca2+ dysregulation, leading to elevated or depressed cardiac contractility, induces compensatory biochemical responses.

Animals↗

PubMed2004

[Effect of mifepristone on the expression of chorionic gonadotropin beta subunit and collagen type IV in female rhesus monkey decidua and villus at early gestation].

OBJECTIVE: To study the effect of mifepristone on the expression of chorionic gonadotropin beta subunit (beta-CG) and collagen type IV in female Rhesus monkey decidua and villus during the first trimester of pregnancy. METHODS: Eighteen sexually mature female Rhesus monkeys were allowed to cohabitate with their male counterparts and diagnosed as being pregnant by B-ultrasound at days 38-45 of the menstrual cycle. They were randomly divided into mifepristone treatment group (15 mg/ml.kg.day, 3 days), control group(no treatment) and CMC-Na treatment group(0.5% CMC-Na, 1 ml/kg.day, 3 days). The content and distribution of chorionic gonadotropin beta subunit and collagen type IV in the female Rhesus monkeys were examined by immunohistochemical technique. RESULTS: Compared with the control group, the immunohistochemical reaction intensity of chorionic gonadotropin beta subunit in the plasm of stroma cells, glandular epithelial cells and decidual cells of decidua, and synctial trophoblast cells of villus significantly decreased in the mifepristone treatment group. The positive staining of collagen type IV surrounding the epithelial glandular basal membrane, decidual cells and blood vessels in decidua and surrounding the synctial trophoblast cells in villus were significantly reduced. CONCLUSION: Mifepristone may have a strong effect in decreasing the bioactivity of beta-CG in decidua and the synthesis of beta-CG in villus, and in accelerating the degradation of collagen type IV in decidua and villus.

Animals↗

PubMed2004

[Expression of androgen receptor and heat shock protein 90alpha in the testicular biopsy specimens of infertile patients with spermatogenic arrest].

OBJECTIVE: To explore the association of spermatogenic arrest with the expression of AR and HSP90alpha. METHODS: The two-step immunohistochemical method was used to examine the expression of AR and HSP90alpha in the testicular biopsy specimens of 57 infertile men with spermatogenic arrest, compared with those taken from 15 normal healthy men. RESULTS: AR was expressed in the nuclei of the spermatogonia, spermatocytes and round spermatids of the normal testicular biopsy, but the intensity of the AR expression showed difference in each type of cells. Furthermore, the high expression of AR in spermatogonia and spermatids was on the margin of the cytoplasm, and perinuclear (forming a ring-like structure) were very distinctive in the spermatogenic arrest testicular biopsy specimens. HSP90alpha was expressed in spermatogonia, spermatocytes, Sertoli cells, Leydig cells and myoid cells in the normal testicular tissues, but highly expressed in the testicular tissues with spermatogenic arrest. The immunostaining intensity of HSP90alpha showed significant difference (P < 0.05) between the two kinds of testicular tissues. CONCLUSION: The results indicate that the abnormal expression sites of AR may make the androgen receptor unable to mediate androgen into the nucleus, which may down-regulate the gene transcription activity of spermatogenic cells. It is possible that the high expression of HSP90alpha may lead to a dramatic decrease in AR stability and an increase in AR abiquitirylation.

Adult↗

PubMed2003

A model experimental system for monitoring changes in sensory neuron phenotype evoked by tooth injury.

The dental pulp is a favorable model for studies of interactions between nociceptive sensory neurons and their peripheral target tissues. In the present study, we retrogradely labeled pulpal afferent neurons with an improved method that permits monitoring of changes in neuronal phenotype in response to controlled tooth injuries. The capacity of retrograde neuronal tracers to diffuse through dentinal tubules was exploited, thereby avoiding the severe injury to the pulp associated with previous tracer application methods. The strategy was to apply the durable fluorescent tracer, Fluoro-gold (FG), to exposed dentin in the floor of shallow cavities in molars, in order to pre-label pulpal neurons in trigeminal ganglia of young adult Sprague-Dawley rats. A high percentage of pupal afferent neurons were retrogradely labeled by application of FG to exposed dentin and the FG fluorescent signal persisted in most labeled neurons for at least 8 weeks. Following tracer application to dentin, the pulp tissue appeared normal histologically, with the exception that a layer of reactive dentin was deposited at the pulp-dentin border beneath the shallow cavities. Assessment of expression of calcitonin gene-related peptide (CGRP) and brain derived neurotrophic factor (BDNF) indicated that pulpal neurons remained in a quiescent, baseline condition cytochemically following application of tracer to cavities in dentin and upregulation of these markers could be detected in neurons that projected to teeth that received a test injury subsequent to tracer application. Thus, labeling of trigeminal neurons via dentinal tubules provides the basis for a useful model for precisely assessing properties of pulpal afferents in both quiescent and activated states.

Administration, Topical↗

PubMed2003

Targeted disruption of the ATP2A1 gene encoding the sarco(endo)plasmic reticulum Ca2+ ATPase isoform 1 (SERCA1) impairs diaphragm function and is lethal in neonatal mice.

Mutations in the ATP2A1 gene, encoding isoform 1 of the sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA1), are one cause of Brody disease, characterized in humans by exercise-induced contraction of fast twitch (type II) skeletal muscle fibers. In an attempt to create a model for Brody disease, the mouse ATP2A1 gene was targeted to generate a SERCA1-null mutant mouse line. In contrast to humans, term SERCA1-null mice had progressive cyanosis and gasping respiration and succumbed from respiratory failure shortly after birth. The percentage of affected homozygote SERCA1(-/-) mice was consistent with predicted Mendelian inheritance. A survey of multiple organs from 10-, 15-, and 18-day embryos revealed no morphological abnormalities, but analysis of the lungs in term mice revealed diffuse congestion and epithelial hypercellularity and studies of the diaphragm muscle revealed prominent hypercontracted regions in scattered fibers and increased fiber size variability. The V(max) of Ca(2+) transport activity in mutant diaphragm and skeletal muscle was reduced by 80% compared with wild-type muscle, and the contractile response to electrical stimulation under physiological conditions was reduced dramatically in mutant diaphragm muscle. No compensatory responses were detected in analysis of mRNAs encoding other Ca(2+) handling proteins or of protein levels. Expression of ATP2A1 is largely restricted to type II fibers, which predominate in normal mouse diaphragm. The absence of SERCA1 in type II fibers, and the absence of compensatory increases in other Ca(2+) handling proteins, coupled with the marked increase in contractile function required of the diaphragm muscle to support postnatal respiration, can account for respiratory failure in term SERCA1-null mice.

Animals↗