Biomedical subjects

X Wu

Publications and source records attributed to X Wu.

At least 451 records · Page 25Linked to original sources

PubMed1999

Control of vascular tone in isolated mesenteric arterial segments from hypertensive patients.

1. Experimental hypertension is associated with several functional alterations of vascular endothelium and smooth muscle, but relatively few studies have examined the control of arterial tone in isolated vascular preparations from patients with essential hypertension. Therefore, we compared functional characteristics in vitro of distal ring segments of the mesenteric artery from 17 hypertensive and 22 normotensive humans. 2. Arterial constrictor responses induced by cumulative addition of Ca(2+) in the presence of noradrenaline (NA) were more effectively inhibited by the Ca(2+) entry blocker nifedipine (0.5 nM) in hypertensive than normotensive subjects (by 55.4+/-4.9, n=17 and 35.0+/(-5.2%), n=22, respectively). Also the contractions elicited by high concentrations of KCl were more effectively inhibited by nifedipine in arterial rings from hypertensive than normotensive patients (by 38.9+/(-3.7), n=17 and 20. 2+/(-4.6%), n=22, respectively). However, the concentration-response curves of contractions to NA, serotonin and KCl in the absence of nifedipine were similar between the study groups. 3. The concentration-response curves of endothelium-dependent relaxations to acetylcholine and Ca(2+) ionophore A23187, as well as of endothelium-independent relaxations to the nitric oxide donor nitroprusside, beta-adrenoceptor agonist isoprenaline and K+ channel opener cromakalim did not show any differences between the groups. Moreover, the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester (0.1 mM) almost abolished the relaxations to acetylcholine and Ca(2+) ionophore in both groups, indicating that these responses were largely mediated by nitric oxide. The function of arterial sodium pump was evaluated by relaxations elicited by the return of K+ upon contractions induced by K+-free solution. The rate of K+-relaxation was similar in hypertensive and normotensive arteries (for all these responses n=20 - 22 in the normotensive and 15 - 17 in the hypertensive group). 4. These results suggest abnormal function of voltage-dependent Ca(2+) channels in arterial smooth muscle of hypertensive patients, whereas vascular responses to endothelium-dependent and -independent vasodilators and classical contractile agents were similar between hypertensive and normotensive subjects. The present findings support the view that blockade of voltage-dependent Ca(2+) channels is an effective means of reducing arterial tone in essential hypertension.

Adult↗

PubMed1999

Bovine chromosome 4 workshop: consensus and comprehensive linkage maps.

The report of the bovine chromosome 4 (BTA4) workshop is presented. Six laboratories contributed a total of 30,168 informative meioses from 62 loci. Twenty-two loci were typed by at least two independent laboratories and were used to construct a consensus linkage map of BTA4. The remaining 40 loci were subsequently incorporated into a comprehensive map. The sex-averaged consensus map covered 131.4 cM. The female map was 124.3 cM in length, while the male map was 134.3 cM. The comprehensive sex-averaged map spanned 141.6 cM. The length of the female and male comprehensive maps were 123.1 cM and 156.4 cM, respectively. Average genetic distance between loci was 6 and 2.3 cM for the consensus and comprehensive linkage maps, respectively.

Animals↗

PubMed1999

Effect of glucose on stress-activated protein kinase activity in mesangial cells and diabetic glomeruli.

BACKGROUND: We have reported that hyperglycemia increases c-jun mRNA levels in isolated glomeruli of diabetic rats. The transcriptional activity of c-jun can be modified by phosphorylation of serine residues in the regulatory domain of the protein by stress-activated protein kinases (SAPKs), but the effect of high glucose concentrations on SAPK expression and activity is unknown. Accordingly, we studied p42/44 MAPK, p38 MAPK, and SAPK expression and activity in primary mesangial cells exposed to high glucose concentrations, as well as SAPK expression and activity in glomeruli of normal and streptozotocin-induced diabetic rats. METHODS: Mesangial cells were incubated in 40 mM glucose for 30 and 60 minutes and 6, 12, 24, and 48 hours, whereas glomeruli of streptozotocin-induced diabetic rats were isolated one day and one and two weeks after the onset of hyperglycemia (blood glucose levels more than 15 mmol/liter), and were compared with age-matched normal rats. Cell lysates were subjected to Western blot analysis of SAPK and phosphorylated SAPK and an in vitro SAPK assay using recombinant c-jun. RESULTS: Western blot analysis revealed that SAPK was expressed, but unphosphorylated, in unstimulated mesangial cells and whole glomerular lysates from normal rats. In accord with these observations, no SAPK activity was detected in lysates from mesangial cells or whole glomeruli from normal rats, although mesangial cell SAPK activity was readily induced in vitro by sorbitol. High glucose concentrations did not increase SAPK activity or lead to detectable phosphorylated SAPK either in vitro or in vivo. In contrast, short-term exposure to 40 mM of glucose activated both p42/44 MAPK and p38 MAPK. CONCLUSIONS: We conclude that high glucose concentrations do not activate SAPK in primary cultured mesangial cells or in diabetic glomeruli during the early phase of diabetic renal hypertrophy.

Animals↗

PubMed1999

Ethnic differences in poly(ADP-ribose) polymerase pseudogene genotype distribution and association with lung cancer risk.

Poly(ADP-ribose) polymerase (PADPRP) is a nuclear DNA-binding enzyme that can modulate chromatin structure close to DNA replication, recombination and repair regions. Two-allele polymorphism on the PADPRP chromosome 13 pseudogene has been studied in several ethnic subpopulations, and the association of each allele with different types of cancer has been investigated. To study the frequency of the allele in the context of lung cancer, we performed a PCR assay for the PADPRP polymorphism in 288 lung cancer patients and 292 matched controls and examined the frequency of the alleles in different ethnic groups. Our results showed that the allele distribution was significantly different among members of different ethnic groups. Specifically, the A allele was dominant in Mexican-American and Caucasian groups but not in the African-American group. The frequencies of the B allele in Mexican-American, Caucasian and African-American controls were 0.184, 0.218 and 0.606, respectively, with the Caucasian cases and controls showing an almost identical lower B allele frequency (0.199 in cases versus 0.218 in controls), and the African-American cases and controls showing an almost identical but considerably higher frequency (0.578 in cases versus 0. 606 in controls). In contrast, the Mexican-American cases and controls exhibited a considerable difference in the B allele frequency (0.306 in cases versus 0.184 in controls). When we combined subjects with the AB or BB genotype into a susceptible genotype group and compared them with the AA group using univariate analysis, the susceptible genotype was not shown to be associated with a risk of lung cancer in either the Caucasian or African-American subpopulation but was significantly associated with an increased risk (2.29-fold) of lung cancer in the Mexican-American group. When lung cancer was categorized by histologic type, no elevated risk was noted for squamous cell carcinoma in any ethnicity. However, in Mexican-Americans, susceptible genotypes were associated with significantly increased risks of adenocarcinoma (3. 21-fold) and large cell carcinoma (10.79). Our study and others have demonstrated that the PADPRP polymorphism may modify an individual's susceptibility to certain cancers. Assessment of the interaction between genetic constitution and environmental exposure might expand our understanding of carcinogenesis and enhance our ability to evaluate the populational cancer risk.

Adenocarcinoma↗

PubMed1999

Mutations of OCTN2, an organic cation/carnitine transporter, lead to deficient cellular carnitine uptake in primary carnitine deficiency.

Systemic primary carnitine deficiency (CDSP, OMIM 212140) is an autosomal recessive disease characterized by low serum and intracellular concentrations of carnitine. CDSP may present with acute metabolic derangement simulating Reye's syndrome within the first 2 years of life. After 3 years of age, patients with CDSP may present with cardiomyopathy and muscle weakness. A linkage with D5S436 in 5q was reported in a family. A recently cloned homologue of the organic cation transporter, OCTN2, which has sodium-dependent carnitine uptake properties, was also mapped to the same locus. We screened for mutation in OCTN2 in a confirmed CDSP family. One truncating mutation (Trp132Stop) and one missense mutation (Pro478Leu) of OCTN2 were identified together with two silent polymorphisms. Expression of the mutant cDNAs revealed virtually no uptake activity for both mutations. Our data indicate that mutations in OCTN2 are responsible for CDSP. Identification of the underlying gene in this disease will allow rapid detection of carriers and postnatal diagnosis of affected patients.

Amino Acid Sequence↗

PubMed1999

Oxidative modification of lipids and proteins in aniline-induced splenic toxicity.

Our earlier studies with aniline suggested the involvement of oxidative stress as an early toxic event in the spleen. In order to understand the status and consequences of the damaging oxidative reactions, especially during the progression of characteristic splenic lesions, time-dependent subchronic studies were conducted in rats. Male Sprague-Dawley rats were treated with 65 mg/kg/day aniline in the drinking water, while control rats received drinking water only. The animals were euthanized after 1, 2, or 3 months of aniline exposure. Total iron content was remarkably greater in the aniline-treated rats than in age-matched controls. There were time-dependent increases in splenic lipid peroxidation of aniline-treated rats. Malondialdehyde-protein adducts were quantitated by a competitive ELISA and showed greater concentrations in the spleens of aniline-treated rats, further substantiating our lipid peroxidation results. Protein oxidation in the spleens of aniline-treated rats was also greater, with a maximum increase of approximately 76% at 3 months. Western blot analysis for oxidized proteins showed two distinct protein bands at approximately 114 kD and approximately 69 kD in both post-nuclear and mitochondrial fractions of the spleens. Furthermore, densitometric analysis of the blot showed increased band intensities of the oxidized proteins in both these spleen fractions from aniline-treated rats, suggesting the susceptibility of these proteins to aniline-induced oxidative stress. The most prominent morphological changes in the spleens of aniline-treated rats included thickening of the capsule, and capsular cells with nuclear prominence and hyperchromia indicative of capsular hyperplasia. These capsular changes and fibrosis of capsule, splenic trabeculae, and red pulp were noted at all three time points after aniline exposure. Our studies thus suggest that aniline-induced oxidative stress in the spleen is an ongoing event that leads to oxidative modifications of biomolecules. Such oxidative modifications, directly or indirectly, could contribute to the splenic toxicity leading to deleterious consequences, including capsular hyperplasia and fibrosis, as observed in this study, and possibly tumorigenesis in chronic aniline exposure conditions.

Aniline Compounds↗

PubMed1999

Human genome anatomy: BACs integrating the genetic and cytogenetic maps for bridging genome and biomedicine.

Human genome sequencing is accelerating rapidly. Multiple genome maps link this sequence to problems in biology and clinical medicine. Because each map represents a different aspect of the structure, content, and behavior of human chromosomes, these fundamental properties must be integrated with the genome to understand disease genes, cancer instability, and human evolution. Cytogenetic maps use 400-850 visible band landmarks and are the primary means for defining prenatal defects and novel cancer breakpoints, thereby providing simultaneous examination of the entire genome. Recent genetic, physical, and transcript maps use PCR-based landmarks called sequence-tagged sites (STSs). We have integrated these genome maps by anchoring the human cytogenetic to the STS-based genetic and physical maps with 1021 STS-BAC pairs at an average spacing of approximately 1 per 3 Mb. These integration points are represented by 872 unique STSs, including 642 polymorphic markers and 957 bacterial artificial chromosomes (BACs), each of which was localized on high resolution fluorescent banded chromosomes. These BACs constitute a resource that bridges map levels and provides the tools to seamlessly translate questions raised by genomic change seen at the chromosomal level into answers based at the molecular level. We show how the BACs provide molecular links for understanding human genomic duplications, meiosis, and evolution, as well as reagents for conducting genome-wide prenatal diagnosis at the molecular level and for detecting gene candidates associated with novel cancer breakpoints.

Chromosome Mapping↗

PubMed1999

Human IgM monoclonal antibody to ganglioside GM2 and complement suppress virus propagation in ex vivo cultures of lymphocytes from HIV-1 infected patients.

HIV-1 infection induces aberrant ganglioside GM2 expression on infected cell lines, and human IgM anti-GM2 monoclonal antibody (L55 Ab) together with normal fresh human serum (FHS) as a source of complement causes complement mediated cytolysis of HIV-1 infected cells as well as HIV-1 particles. We report here that high expression of GM2 was also detected on HIV-1 infected lymphocytes from HIV-1 seropositive patients. L55 Ab effectively suppressed the generation of HIV in the presence of FHS in primarily cultured lymphocytes from HIV-1 infected patients in ex vivo experiments, and the suppression was enhanced additively by AZT. These data suggest that L55 Ab may increase the therapeutic effect of chemotherapy.

Antibodies, Monoclonal↗

PubMed1999

Effects of continuous versus intermittent ethanol exposure on rat sympathetic neurons.

BACKGROUND: Binge ethanol exposure is known to induce degeneration of central nervous system (CNS) neurons. Sympathetic hyperactivity has been related to ethanol withdrawal symptoms, but the effects of repeated withdrawals on peripheral sympathetic neurons have not been studied previously. METHODS: The effects of continuous versus intermittent ethanol consumption on sympathetic neurons of the superior cervical ganglion (SCG) were studied in male Wistar rats. Two-month-old rats were divided into three groups: one group with ethanol (10% v/v) as the drinking fluid throughout the 51/2-month experiment (continuous, n = 9), one group drinking ethanol on 4 days/week and water on 3 days/week (intermittent, n = 9), and a control group (n = 9) with water as the only available fluid. All groups had food ad libitum. SCG volume, neuron density, and total number of neurons were measured by using unbiased morphometric methods. RESULTS: As the mean daily ethanol consumption did not differ between the two ethanol-exposed groups (continuous 5.7 g/kg/day versus intermittent 5.8 g/kg/day), the total dose of ethanol consumed was 42% smaller in the intermittent group. The total number of SCG neurons decreased by 28%, and neuron density by 23%, in the intermittent group compared with the control group, whereas no significant neuron loss was observed in the continuous group. The volume of the SCG was similar in all study groups. The results suggest that repeated ethanol withdrawals, rather than ethanol exposure per se, are deleterious to sympathetic neurons. CONCLUSIONS: Ethanol-induced degeneration of neurons is not only related to the amount of ethanol consumed, but also to the patterns of drinking.

Adrenergic Fibers↗

PubMed1999

Variation of spectral power immediately prior to spontaneous onset of ventricular tachycardia/ventricular fibrillation in implantable cardioverter defibrillator patients.

INTRODUCTION: Short-term heart rate variability (HRV) may change immediately before onset of a ventricular arrhythmia (ONSET). METHODS AND RESULTS: Power spectrum analysis was performed on instantaneous heart rate (IHR; including all beats) and normal heart rate (NHR; excluding ectopics) curves obtained at equally spaced 0.5-second intervals using a cubic spline. The database consisted of 135 sets of 1,024 RR intervals leading to ventricular arrhythmia (VA) and controls from 78 patients. Total periodogram and time course of spectral power were obtained. Ten spectral bands of 0.1-Hz bandwidth (0 to 1 Hz) were analyzed. A simple threshold technique was retrospectively used to predict the onset of a VA. RR intervals that led to VA ONSET had significantly higher total spectral power than controls (P < 0.001 for both NHR and IHR for every band). Spectral power remained constant until 100 seconds before ONSET and then increased significantly in the time window immediately preceding ONSET (P < 0.02 compared with others). Using a simple threshold method, a predictive accuracy of 68%+/-1.4% was obtained with different window sizes. Using specific spectral bands, the predictive accuracy of VA ONSET could be improved to 76% for IHR and 71% for NHR (0.8- to 0.9-Hz band). CONCLUSION: Our results suggest that a sustained higher power increase in NHR and IHR occurs during the course of 12.11+/-.57 minutes, followed by a sudden elevation in spectral power within 100 seconds of ONSET, and may be a precursor to ventricular tachycardia/ventricular fibrillation episodes.

Algorithms↗

PubMed1999

Measurement of x-ray attenuation coefficients of aqueous solutions of indocyanine green and glycated chitosan.

We report our experimental results of measurements of x-ray attenuation coefficients of aqueous solutions of a light absorbing dye, indocyanine green, and an immunoadjuvant, glycated chitosan. In the treatment of metastatic tumors in rats using a novel laser immunotherapy these solutions were administered in situ. The x-ray attenuation data of the solutions are essential to development of an x-ray digital imaging system for monitoring the administration of the solution, as well as for the distribution and the diffusion of the solution in tumors and in surrounding tissue. The composition of the solutions, the measurement system configuration, and the technique used to determine the attenuation coefficients are described. The experimental results show that glycated chitosan has a higher attenuation coefficient compared to indocyanine green and water. Our experimental data proved that, even at low concentrations, the x-ray attenuation through these aqueous solutions could be differentiated. Therefore, a digital x-ray imaging technique can be used effectively in monitoring and controlling the intratumor diffusion and distributions of these solutions.

Adjuvants, Immunologic↗

PubMed1999

Influence of different functional elements of plasmid pGT232 on maintenance of recombinant plasmids in Lactobacillus reuteri populations in vitro and in vivo.

Plasmid pGT232 (5.1 kb), an indigenous plasmid of Lactobacillus reuteri 100-23, was determined, on the basis of nucleotide and deduced protein sequence data, to belong to the pC194-pUB110 family of plasmids that replicate via the rolling-circle mechanism. The minimal replicon of pGT232 was located on a 1.7-kb sequence consisting of a double-strand origin of replication and a gene encoding the replication initiation protein, repA. An erythromycin-selectable recombinant plasmid containing this minimal replicon was stably maintained (>97% erythromycin-resistant cells) without antibiotic selection in an L. reuteri population under laboratory growth conditions but was poorly maintained (<33% resistant cells) in the L. reuteri population inhabiting the murine gastrointestinal tract. Stable maintenance (>90% resistant cells) of pGT232-derived plasmids in the lactobacillus population in vivo required an additional 1.0-kb sequence which contained a putative single-strand replication origin (SSO). The SSO of pGT232 is believed to be novel and functions in an orientation-specific manner.

Amino Acid Sequence↗

PubMed1999

Targeting human immunodeficiency virus (HIV) type 2 integrase protein into HIV type 1.

Integrase (IN) is the only retroviral enzyme necessary for the integration of retroviral cDNA into the host cell's chromosomes. The structure and function of IN is highly conserved. The human immunodeficiency virus type 2 (HIV-2) IN has been shown to efficiently support 3' processing and strand transfer of HIV-1 DNA substrate in vitro. To determine whether HIV-2 IN protein (IN(2)) could substitute for HIV-1 IN function in vivo, we used HIV-1 Vpr to deliver the IN(2) into IN mutant HIV-1 virions by expression in trans as a Vpr-IN fusion protein. Trans-complementation with IN(2) markedly increased the infectivity of IN-minus HIV-1. Compared with the homologous trans-IN protein, infectivity was increased to a level of 16%. Since IN has been found to play a role in reverse transcription (Wu et al., J. Virol. 73:2126-2135, 1999), cells infected with IN(2)-complemented HIV-1 were analyzed for DNA products of reverse transcription. DNA levels of approximately 18% of that of wild type were detected. The homologous trans-IN protein restored the synthesis of viral cDNA to approximately 86% of that of wild-type virus. By complementing integration-defective HIV-1 IN mutant viruses, which were not impaired in cDNA synthesis, the trans-IN(2) protein was shown to support integration up to a level of 55% compared with that of the homologous trans-IN protein. The delivery of heterologous IN protein into HIV-1 particles in trans offers a novel approach to understand IN protein function in vivo.

DNA, Complementary↗

PubMed1999

Human immunodeficiency virus type 1 integrase protein promotes reverse transcription through specific interactions with the nucleoprotein reverse transcription complex.

The human immunodeficiency virus type 1 (HIV-1) integrase protein (IN) is essential for integration of the viral DNA into host cell chromosomes. Since IN is expressed and assembled into virions as part of the 160-kDa Gag-Pol precursor polyprotein and catalyzes integration of the provirus in infected cells as a mature 32-kDa protein, mutations in IN are pleiotropic and may affect virus replication at different stages of the virus life cycle in addition to integration. Several different phenotypes have been observed for IN mutant viruses, including defects in virion morphology, protein composition, reverse transcription, nuclear import, and integration. Because the effects of mutations in the IN domain of Gag-Pol can not always be distinguished from those of mutations in the mature IN protein, there remains a significant gap in our understanding of IN function in vivo. To directly analyze the function of the mature IN protein itself, in the context of a replicating virus but independently from that of Gag-Pol, we used an approach developed in our laboratory for incorporating proteins into HIV virions by their expression in trans as fusion partners of either Vpr or Vpx. By providing IN in trans as a Vpr-IN fusion protein, our analysis revealed, for the first time, that the mature IN protein is essential for the efficient initiation of reverse transcription in infected cells and that this function does not require the IN protein to be enzymatically (integration) active. Our findings of a direct physical interaction between IN and reverse transcriptase and the failure of heterologous HIV-2 IN protein to efficiently support reverse transcription indicate that this novel function occurs through specific interactions with other viral components of the reverse transcription initiation complex. Studies involving complementation between integration- and DNA synthesis-defective IN mutants further support this conclusion and reveal that the highly conserved HHCC motif of IN is important for both activities. These findings provide important new insights into IN function and reverse transcription in the context of the nucleoprotein reverse transcription complex within the infected cell. Moreover, they validate a novel approach that obviates the need to mutate Gag-Pol in order to study the role of its individual mature components at the virus replication level.

DNA, Viral↗

PubMed1999

Influence of chronic ethanol consumption on arterial tone in young and aged rats.

The aim of this work was to evaluate the effects of long-term ethanol consumption on arterial responses in vitro in young and aged rats. Therefore, Wistar rats (ages 3 and 29 mo, respectively) were allocated to six groups: control-young, sucrose-young, ethanol-young, control-aged, sucrose-aged, and ethanol-aged. The ethanol-fed groups were given 25% ethanol by intragastric gavage three times a day 4 days a week. Responses of mesenteric arterial rings were examined in standard organ chambers after 5 treatment weeks. In norepinephrine-precontracted arterial rings, endothelium-dependent relaxations to acetylcholine, as well as endothelium-independent relaxations to isoproterenol, were attenuated in aged rats when compared with young controls. Relaxation responses to isoproterenol, but not to acetylcholine and nitroprusside, were clearly improved by ethanol treatment in both young and aged rats. The cyclooxygenase inhibitor diclofenac, which reduces the synthesis of dilating and constricting prostanoids, enhanced the relaxation to acetylcholine in all three aged rat groups but was without significant effect in the young rats. In the presence of the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester the relaxation to acetylcholine in control and sucrose-fed aged rats was markedly reduced compared with control rats, whereas in the young controls and in both young and aged ethanol-exposed groups, distinct relaxations to higher concentrations of acetylcholine were still present. The endothelium-independent relaxations to cromakalim, a hyperpolarizing vasodilator acting via ATP-sensitive potassium channels, were also markedly augmented by ethanol feeding in both young and aged rats. In conclusion, ethanol consumption in both young and aged rats was associated with markedly improved arterial relaxations to isoproterenol and cromakalim, as well as clearly augmented relaxation to acetylcholine during inhibition of cyclooxygenase and nitric oxide synthase. These findings suggest that especially the potassium channel-related component of arterial relaxation was augmented by long-term ethanol exposure.

Acetylcholine↗

PubMed1999

Male reproductive toxicity and beta-luteinizing hormone gene expression in sexually mature and immature rats exposed to 2-bromopropane.

1. The reproductive effects of 2-bromopropane (2-BP) in sexually mature and immature male Sprague-Dawley rats were investigated. The animals were randomly divided into three treatment groups and one control group each of which comprised six mature and six immature rats. The treated groups were injected s.c. 200, 600 and 1800 mg/kg of 2-BP on 5 days a week for 5 - 7 weeks and the control group received the vehicle. 2. The absolute and relative testis weights were significantly reduced in 600 and 1800 mg/kg b.w. dose groups in both mature and immature rats. The absolute epididymis, prostate, seminal vesicle, and pituitary weights and the relative epididymis weights, however, were significant only at the highest dose level used in both mature and immature rats. 3. The sperm concentration and sperm viability in epididymal duct decreased and the percentage of abnormal sperm increased in a dose-dependent manner in both mature and immature rats. Additionally, serum testosterone level was significantly decreased in all dose groups in mature rats, and was significantly reduced only in the group treated with the middle and highest dose in immature rats. 4. In both mature and immature rats treated with 200 and 600 mg/kg, the seminiferous tubules were atrophied and all types of germ cells were decreased in number. At the highest dose level, the effect was more marked showing severely atrophied seminiferous tubules and a complete loss of all types of germ cells. 5. The mating, pregnancy and fertility indices were significantly reduced in the 600 and 1800 mg/kg groups. Additionally, at the highest dose group the number of implantations and viable fetuses per litter were reduced and the resorption rate was increased significantly. 6. In the mature rats, the beta-LH gene expression increased significantly in the 1800 mg/kg group when compared to the control group. 7. It can be concluded that 2-BP induces alterations in both neuro-endocrine axis and the reproductive tract under the present experimental conditions. The no observed adverse effect level (NOAEL) in this study could be estimated to be lower than 200 mg/kg/b.w. based on the alteration in testicular morphology as well as on sperm parameters observed at the dose level of 200 mg/kg.

Animals↗

PubMed1999

A corepressor and chicken ovalbumin upstream promoter transcriptional factor proteins modulate peroxisome proliferator-activated receptor-gamma2/retinoid X receptor alpha-activated transcription from the murine lipoprotein lipase promoter.

Complex physiological stimuli differentially regulate the tissue-specific transcription of the lipoprotein lipase (LPL) gene. A conserved DNA recognition element (-171 to -149 bp) within the promoter functions as a transcriptional enhancer when bound by the peroxisome proliferator-activated receptor-gamma2 (PPARgamma2)/retinoid X receptor alpha (RXRalpha) heterodimer, but serves as a transcriptional silencer in the presence of unidentified double and single stranded DNA-binding proteins. To address this apparent paradox, the current study examined the effect of two classes of candidate comodulatory proteins, COUP-TF (chicken ovalbumin upstream promoter transcriptional factor) and the corepressor SMRT (silencing mediator of retinoic acid receptor and thyroid receptor). The expression of COUP-TF was detected by Western and Northern blots in a preadipocyte 3T3-L1 cell model during periods corresponding to increased LPL transcription. Cotransfection of COUP-TF expression constructs in the renal epithelial 293T cell line significantly increased transcription from the LPL promoter in synergy with PPARgamma2/RXRalpha heterodimers. The COUP-TFII (ARP-1) protein specifically bound the LPL PPAR recognition element inelectromobility shift assays and interacted directly with the ligand-binding domain of PPARgamma in pull-down experiments. In contrast, cotransfection of SMRT repressed PPARgamma2/ RXRalpha-mediated LPL transcription in the absence or presence of COUP-TFII (ARP-1). The interaction between PPARgamma2 and SMRT localized to the receptor-interactive domain 2 (amino acids 1260-1495) of the SMRT protein based on cotransfection and pull-down assays. These in vitro data indicate that COUP-TF proteins and SMRT modulate PPARgamma-mediated LPL transcription in the 293T cell line.

3T3 Cells↗

PubMed1999

The suppression of testis-brain RNA binding protein and kinesin heavy chain disrupts mRNA sorting in dendrites.

Ribonucleoprotein particles (RNPs) are thought to be key players in somato-dendritic sorting of mRNAs in CNS neurons and are implicated in activity-directed neuronal remodeling. Here, we use reporter constructs and gel mobility shift assays to show that the testis brain RNA-binding protein (TB-RBP) associates with mRNPs in a sequence (Y element) dependent manner. Using antisense oligonucleotides (anti-ODN), we demonstrate that blocking the TB-RBP Y element binding site disrupts and mis-localizes mRNPs containing (alpha)-calmodulin dependent kinase II (alpha)-CAMKII) and ligatin mRNAs. In addition, we show that suppression of kinesin heavy chain motor protein alters only the localization of (alpha)-CAMKII mRNA. Thus, differential sorting of mRNAs involves multiple mRNPs and selective motor proteins permitting localized mRNAs to utilize common mechanisms for shared steps.

Animals↗