Biomedical subjects

W Li

Publications and source records attributed to W Li.

At least 739 records · Page 41Linked to original sources

PubMed1998

Point mutation in intron sequence causes altered carboxyl-terminal structure in the aryl hydrocarbon receptor of the most 2,3,7,8-tetrachlorodibenzo-p-dioxin-resistant rat strain.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is the most potent dioxin. There are exceptionally wide inter- and intraspecies differences in sensitivity to TCDD toxicity with Han/Wistar (H/W) (Kuopio) rats being the most resistant mammals tested. A peculiar feature of H/W rats is that despite their unresponsiveness to the acute lethality of TCDD, their sensitivity to other biological impacts of TCDD (e.g., CYP1A1 induction) is preserved. The biological effects of TCDD are mediated by the aryl hydrocarbon receptor (AhR). We recently found that the AhR of H/W rats (about 98 kDa) is smaller than the receptor in other rat strains (106 kDa). In the present study, molecular cloning and sequencing of the H/W rat AhR revealed that the reason for its smaller size is a deletion/insertion-type change at the 3' end of exon 10 in the receptor cDNA. This change emanates from a single point mutation at the first nucleotide of intron 10, resulting in altered mRNA splicing. At the protein level, the mutation leads to a total loss of either 43 or 38 amino acids (with altered sequence for the last seven amino acids in the latter case) toward the carboxyl-terminal end in the trans-activation domain of the AhR. H/W rats also harbor a point mutation in exon 10 that will cause a Val-to-Ala substitution in codon 497, but this occurs in a variable region of the AhR. These findings suggest that there is a relatively small region in the AhR trans-activation domain that may be capable of providing selectivity to its function.

Animals↗

PubMed1998

Oral administration of a prodrug of the influenza virus neuraminidase inhibitor GS 4071 protects mice and ferrets against influenza infection.

We have recently described GS 4071, a carbocyclic transition-state analog inhibitor of the influenza virus neuraminidase, which has potent inhibitory activity comparable to that of 4-guanidino-Neu5Ac2en (GG167; zanamivir) when tested against influenza A virus replication and neuraminidase activity in vitro. We now report that GS 4071 is active against several strains of influenza A and B viruses in vitro and that oral GS 4104, an ethyl ester prodrug which is converted to GS 4071 in vivo, is active in the mouse and ferret models of influenza virus infection. Oral administration of 10 mg of GS 4104 per kg of body weight per day caused a 100-fold reduction in lung homogenate viral titers and enhanced survival in mice infected with influenza A or B viruses. In ferrets, a 25-mg/kg dose of GS 4104 given twice daily reduced peak viral titers in nasal washings and eliminated constitutional responses to influenza virus infection including fever, increased nasal signs (sneezing, nasal discharge, mouth breathing), and decreased activity. Consistent with our demonstration that the parent compound is highly specific for influenza virus neuraminidases, no significant drug-related toxicity was observed after the administration of oral dosages of GS 4104 of up to 800 mg/kg/day for 14 days in nonclinical toxicology studies with rats. These results indicate that GS 4104 is a novel, orally active antiviral agent with the potential to be used for the prophylaxis and treatment of influenza A and B virus infections.

Acetamides↗

PubMed1998

Identification of GS 4104 as an orally bioavailable prodrug of the influenza virus neuraminidase inhibitor GS 4071.

GS 4071 is a potent carbocyclic transition-state analog inhibitor of influenza virus neuraminidase with activity against both influenza A and B viruses in vitro. GS 4116, the guanidino analog of GS 4071, is a 10-fold more potent inhibitor of influenza virus replication in tissue culture than GS 4071. In this study we determined the oral bioavailabilities of GS 4071, GS 4116, and their respective ethyl ester prodrugs in rats. Both parent compounds and the prodrug of the guanidino analog exhibited poor oral bioavailability (2 to 4%) and low peak concentrations in plasma (Cmaxs; Cmax <0.06 microg/ml). In contrast, GS 4104, the ethyl ester prodrug of GS 4071, exhibited good oral bioavailability (35%) as GS 4071 and high Cmaxs of GS 4071 (Cmax = 0.47 microg/ml) which are 150 times the concentration necessary to inhibit influenza virus neuraminidase activity by 90%. The bioavailability of GS 4104 as GS 4071 was also determined in mice (30%), ferrets (11%), and dogs (73%). The plasma of all four species exhibited high, sustained concentrations of GS 4071 such that at 12 h postdosing the concentrations of GS 4071 in plasma exceeded those necessary to inhibit influenza virus neuraminidase activity by 90%. These results demonstrate that GS 4104 is an orally bioavailable prodrug of GS 4071 in animals and that it has the potential to be an oral agent for the prevention and treatment of influenza A and B virus infections in humans.

Acetamides↗

PubMed1998

Regulation of transforming growth factor alpha expression in a growth factor-independent cell line.

Aberrant transcriptional regulation of transforming growth factor alpha (TGF alpha) appears to be an important contributor to the malignant phenotype and the growth factor independence with which malignancy is frequently associated. However, little is known about the molecular mechanisms responsible for dysregulation of TGF alpha expression in the malignant phenotype. In this paper, we report on TGF alpha promoter regulation in the highly malignant growth factor-independent cell line HCT116. The HCT116 cell line expresses TGF alpha and the epidermal growth factor receptor (EGFR) but is not growth inhibited by antibodies to EGFR or TGF alpha. However, constitutive expression of TGF alpha antisense RNA in the HCT116 cell line resulted in the isolation of clones with markedly reduced TGF alpha mRNA and which were dependent on exogenous growth factors for proliferation. We hypothesized that if TGF alpha autocrine activation is the major stimulator of TGF alpha expression in this cell line, TGF alpha promoter activity should be reduced in the antisense TGF alpha clones in the absence of exogenous growth factor. This was the case. Moreover, transcriptional activation of the TGF alpha promoter was restored in an antisense-TGF alpha-mRNA-expressing clone which had reverted to a growth factor-independent phenotype. Using this model system, we were able to identify a 25-bp element within the TGF alpha promoter which conferred TGF alpha autoregulation to the TGF alpha promoter in the HCT116 cell line. In the TGF alpha-antisense-RNA-expressing clones, this element was activated by exogenous EGF. This 25-bp sequence contained no consensus sequences of known transcription factors so that the TGF alpha or EGF regulatory element within this 25-bp sequence represents a unique element. Further characterization of this 25-bp DNA sequence by deletion analysis revealed that regulation of TGF alpha promoter activity by this sequence is complex, as both repressors and activators bind in this region, but the overall expression of the activators is pivotal in determining the level of response to EGF or TGF alpha stimulation. The specific nuclear proteins binding to this region are also regulated in an autocrine-TGF alpha-dependent fashion and by exogenous EGF in EGF-deprived TGF alpha antisense clone 33. This regulation is identical to that seen in the growth factor-dependent cell line FET, which requires exogenous EGF for optimal growth. Moreover, the time response of the stimulation of trans-acting factor binding by EGF suggests that the effect is directly due to growth factor and not mediated by changes in growth state. We conclude that this element appears to represent the major positive regulator of TGF alpha expression in the growth factor-independent HCT116 cell line and may represent the major site of transcriptional dysregulation of TGF alpha promoter activity in the growth factor-independent phenotype.

Cell Division↗

PubMed1998

Protein kinase C-delta is an important signaling molecule in insulin-like growth factor I receptor-mediated cell transformation.

To investigate the potential role of protein kinase C-delta (PKC-delta) in insulin-like growth factor I receptor (IGF-IR)-mediated cell transformation, an oncogenic gag-IGF-IR beta-fusion receptor lacking the entire extracellular domain, which was designated NM1, and a full-length IGF-IR were coexpressed with either wild-type PKC-delta (PKC-deltaWT) or an ATP-binding mutant of PKC-delta (PKC-deltaK376R) in NIH 3T3 fibroblasts. While overexpression of PKC-deltaWT did not affect NM1- and IGF-IR-induced focus and colony formation of NIH 3T3 cells, expression of PKC-deltaK376R severely impaired these events. In contrast, NM1-mediated cell growth in monolayer was not affected by coexpressing PKC-deltaK376R. PKC-deltaWT and PKC-deltaK376R were constitutively phosphorylated on a tyrosine residue(s) in the NM1- and IGF-IR-expressing cells and were associated with them in an IGF-I-independent manner. Activated IGF-IR was able to phosphorylate purified PKC-delta in vitro and stimulated its kinase activity. Furthermore, the level of endogenous PKC-delta protein was up-regulated through transcriptional activation in response to long-term IGF-IR activation. Taken together, our results demonstrate that PKC-delta plays an important role in IGF-IR-mediated cell transformation, probably via association of the receptor with PKC-delta and its activation through protein up-regulation and tyrosine phosphorylation. Competition with endogenous PKC-delta for NM1 and IGF-IR association by PKC-deltaK376R is probably an important mechanism underlying the PKC-deltaK376R-mediated inhibition of cell transformation by NM1 and IGF-IR.

3T3 Cells↗

PubMed1998

Premature translation of oskar in oocytes lacking the RNA-binding protein bicaudal-C.

Bicaudal-C (Bic-C) is required during Drosophila melanogaster oogenesis for several processes, including anterior-posterior patterning. The gene encodes a protein with five copies of the KH domain, a motif found in a number of RNA-binding proteins. Using antibodies raised against the BIC-C protein, we show that multiple isoforms of the protein exist in ovaries and that the protein, like the RNA, accumulates in the developing oocyte early in oogenesis. BIC-C protein expressed in mammalian cells can bind RNA in vitro, and a point mutation in one of the KH domains that causes a strong Bic-C phenotype weakens this binding. In addition, oskar translation commences prior to posterior localization of oskar RNA in Bic-C- oocytes, indicating that Bic-C may regulate oskar translation during oogenesis.

Alleles↗

PubMed1998

Fetal fast MR imaging: reproducibility, technical quality, and conspicuity of anatomy.

PURPOSE: To evaluate the normal appearance of fetal anatomy, the conspicuity of fetal organs, the reproducibility of images, and the limitations to image quality with the use of half-Fourier, single-shot rapid acquisition with relaxation enhancement (RARE) magnetic resonance (MR) imaging. MATERIALS AND METHODS: Fifty-four fetuses of 49 pregnancies underwent MR imaging with the half-Fourier, single-shot RARE technique. Two reviewers attempted to identify 47 organs and anatomic regions in each fetus. Organ or region conspicuity, image quality, and the limitations of image quality were graded. RESULTS: Fetal anatomy was well depicted in fetuses over 20 weeks in gestational age. Fetal imaging was limited by gestational age of 20 weeks or less usually owing to the small size of the organ or region being evaluated and, less frequently, by motion. CONCLUSION: Half-Fourier, single-shot RARE MR imaging provided a detailed and reproducible evaluation of normal fetal anatomy, which can be used as a standard of reference in MR imaging of fetal anomalies.

Artifacts↗

PubMed1998

Recovery of semicircular canal primary afferent activity in the pigeon after streptomycin ototoxicity.

Recovery of semicircular canal primary afferent activity in the pigeon after streptomycin ototoxicity. J. Neurophysiol. 80: 3297-3311, 1998. The electrophysiological activity of horizontal semicircular canal primary afferents (HSCPA) was investigated in vivo in the barbiturate-anesthetized pigeon by means of extracellular single-fiber vestibular nerve action potential recordings. The spontaneous and driven discharges to pulse (step/trapezoid waveform, peak velocity = 120 degrees/s) and sum-of-sines (0.03, 0.09, 0.21, 0.39, 0.93, 1.83 Hz, peak velocity = 30 degrees/s for each frequency) rotations were measured both in normal control animals and a group of animals at 30, 40, 50, 60, 71, and 150 days postinjection sequence (PIS) of streptomycin sulfate. Prior to 30 days PIS, the activity in the nerve was not appropriately modulated during and after rotation. At 30 days PIS and thereafter, the responses resembled those observed in control animals but with systematic changes in parameters of fitted pulse responses and fitted Bode plots as days PIS increased. The return of parameters characterizing the neural dynamics of the semicircular canals were monotonic and could be best described by either linear or exponential functions. After 30 days PIS, the mechanical cupula-endolymph system, the function of which can be inferred from the cupula long time constant (tauL) following step velocity, did not change systematically (tauL = 6.92 +/- 3.96, 8.64 +/- 5.52, 8.35 +/- 4.21, 10.00 +/- 2.79, 9.05 +/- 3.67, 7.05 +/- 2.72; means +/- SD). However, the mean gain (G) of the HSCPA response to pulse rotation nearly doubled between 30 and 150 days PIS (from 1.31 +/- 0. 39 to 2.40 +/- 1.04) and returned linearly to control values (G = 2. 39 +/- 0.77) over this time period [G = 1.33 + 0.009(PIS-30), R2 = 0. 92, P < 0.05]. Meanwhile, neural adaptation as quantitated using a fractional operator, k, decayed exponentially (single exponential) to an asymptote. The time constant of this exponential was approximately 55 days [k = 0.034 + 0.33e-(PIS-30)/55.4, R2 = 0.99, P < 0.01]. Features of the spontaneous discharge previously shown to be correlated with k changed appropriately. That is, the coefficient of variation (CV) and frequency of firing (FF) decayed and grew asymptotically, respectively. These parameters also exhibited an exponential time course of return to control values from 30 to 150 days PIS [CV = 0.44 + 0.65e-(PIS-30)/21.5, R2 = 0.96, P < 0.01, and FF = 39.97 + 101.42(1 - e-(PIS-30)/32.6), R2 = 0.97, P < 0.01]. The trends of recovery for G, k, and tauL derived from analysis of the pulse response were confirmed by strong positive correlations with best fitted parameters obtained from analysis of the sum-of-sines frequency domain response of HSCPAs. There were statistically significant correlations (r = 0.90, P < 0.05 and r = 0.93, P < 0.05) between parameters (G, k) derived from pulse responses and those (G', k') from sum-of-sines responses, respectively. The cupula time constant based on sum-of-sines' data (tau'L) showed no statistically significant change between 30 and 150 days PIS (P > 0.05, analysis of variance). Thus the results in present study indicate that both the spontaneous discharge and the driven response to rotation of pigeon HSCPAs recovered their normal physiological status between 30 and 150 days PIS after hair cell death due to aminoglycoside ototoxicity. The recovery was systematic for the parameters chosen to be tested with the exception of the cupula long time constant, tauL. The mechanisms (changes in ciliary dynamics, changes in hair cell ionic currents, changes in bouton terminals, etc.) underlying these changes await further morphophysiological studies.

Action Potentials↗

PubMed1998

Regulatory effects of soluble growth factors on choriocapillaris endothelial growth and survival.

The effects of soluble growth factors on regulating the survival and growth of choriocapillaris endothelial (CCE) cells were investigated in vitro. CCE cells were cultured in a serum-free medium in the presence or absence of various soluble growth factors. Cell growth and cell viability were assessed by counting viable cells. Results showed that acidic fibroblast growth factor (aFGF), basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) significantly stimulated CCE growth in a dose-dependent manner. Platelet-derived growth factor BB (PDGF, 0.4-10 ng/ml), insulin-like growth factor (IGF, 0.4-10 ng/ml) or insulin (0.4-10 micrograms/ml) alone did not affect the growth of CCE cells. In the presence of insulin (10 micrograms/ml), however, PDGF stimulated CCE growth in a dose-dependent manner. By contrast, transforming growth factor beta 1 (TGF-beta 1) induced CCE death in the absence of other growth factors and inhibited the CCE growth induced by aFGF, bFGF or VEGF. When CCE cells had been cultured in media containing aFGF, bFGF, VEGF or the combination of PDGF and insulin for 48 h, withdrawal of aFGF, bFGF or VEGF, but not PDGF, from the media resulted in CCE death. The CCE death induced by either an introduction of TGF-beta 1 or withdrawal of aFGF, bFGF or VEGF was defined as apoptosis based on morphologic characteristics (condensation and fragmentation of nuclei, shrinkage of cells in size) and DNA fragmentation in multiples of approximately 180 base pairs. Phorbol 12-myristate 13-acetate (PMA, 2 or 5 nM) protected CCE cells against apoptosis induced by the introduction of TGF-beta 1 and withdrawal of aFGF, bFGF or VEGF, while H7 (50 microM), but not HA1004 (50 microM), abrogated the protective effect of PMA on CCE apoptosis. However, cycloheximide (0.1 microM), a protein synthesis inhibitor, was only effective to protect CCE cells from apoptosis induced by aFGF, bFGF or VEGF withdrawal, but not that induced by the introduction of TGF-beta 1. Moreover, cycloheximide and a low concentration of PMA (2 nM) showed an additive effect on protecting CCE cells from apoptosis as the result of a growth factor withdrawal. These data may suggest that some growth factors, such as aFGF, bFGF, VEGF and TGF-beta 1, play a more critical role than the others, such as PDGF and IGF, in the regulation of CCE growth and survival. CCE apoptosis as a result of withdrawal of a survival factor or of receiving a death factor such as TGF-beta 1 may involve different mechanisms, which merits further study.

Animals↗

PubMed1998

Uptake of oxidized LDL by macrophages results in partial lysosomal enzyme inactivation and relocation.

The cytotoxicity of oxidized LDL (oxLDL) to several types of artery wall cells might contribute to atherosclerosis by causing cell death, presumably by both apoptosis and necrosis. After its uptake into macrophage lysosomes by receptor-mediated endocytosis, oxLDL is poorly degraded, resulting in ceroid-containing foam cells. We studied the influence ofoxLDL on lysosomal enzyme activity and, in particular, on lysosomal membrane stability and the modulation of these cellular characteristics by HDL and vitamin E (vit-E). Unexposed cells and cells exposed to acetylated LDL (AcLDL) were used as controls. The lysosomal marker enzymes cathepsin L and N-acetyl-beta-glucosaminidase (NAbetaGase) were biochemically assayed in J-774 cells after fractionation. Lysosomal integrity in living cells was assayed by the acridine orange (AO) relocation test. Cathepsin D was immunocytochemically demonstrated in J-774 cells and human monocyte-derived macrophages. We found that the total activities of NAbetaGase and cathepsin L were significantly decreased, whereas their relative cytosolic activities were enhanced, after oxLDL exposure. Labilization of the lysosomal membranes was further proven by decreased lysosomal AO uptake and relocation to the cytosol of cathepsin D, as estimated by light and electron microscopic immunocytochemistry. HDL and vit-E diminished the cytotoxicity of oxLDL by decreasing the lysosomal damage. The results indicate that endocytosed oxLDL not only partially inactivates lysosomal enzymes but also destabilizes the acidic vacuolar compartment, causing relocation of lysosomal enzymes to the cytosol. Exposure to AcLDL resulted in its uptake with enlargement of the lysosomal apparatus, but the stability of the lysosomal membranes was not changed.

Acridine Orange↗

PubMed1998

Thrombolysis with intravenous rtPA in a series of 100 cases of acute carotid territory stroke: determination of etiological, topographic, and radiological outcome factors.

BACKGROUND AND PURPOSE: Although new, large, double-blind, randomized studies are needed to establish the efficiency of intravenous thrombolysis, open trials of sufficient size may also provide novel data concerning specific outcomes after thrombolysis. METHODS: An open study of intravenous rtPA in 100 patients with internal carotid artery (ICA) territory strokes between 20 and 81 years of age, with a baseline Scandinavian Stroke Scale (SSS) score of <48 at entry was conducted. Inclusion time was within 7 hours after stroke onset. rtPA (0.8 mg/kg) was infused for 90 minutes, with an initial 10% bolus. Heparin was given according to 3 consecutive protocols. The SSS evaluation was done on days 0, 1, 7, 30, and 90. CT scan was performed before treatment, on days 1 and 7. Etiological investigations included echocardiography and carotid Doppler sonography and/or angiography. Outcome at 1 year was documented by SSS score, the modified Rankin Scale (mRS) score, and a 10-point invalidity scale. Multivariate logistic regression was used to identify predictors of poor versus good outcome. RESULTS: At day 90, 45 patients (45%) had a good result, defined as complete regression or slight neurological sequelae (mRS score of 0-1), 18 patients had a moderate outcome (mRS 2-3), and 31 patients had serious neurological sequelae (mRS 4-5). Six patients died, 2 with intracerebral hematoma after immediate heparin. Five of 11 patients (45.5%) treated between 6 and 7 hours had a good result. The overall intracerebral hematoma rate was 7%. Higher values of fibrin degradation products at 2 hours were observed in the subgroup with intracerebral hematomas. Significant predictors of poor outcome on multivariate logistic regression analysis were baseline SSS score of <15 (odds ratio [OR], 3.38; 95% confidence interval [CI], 1.07 to 10. 74; P=0.04), indistinction between white and gray matter on CT scan (OR, 6.59; 95% CI, 2.19 to 19.79; P=0.0008), and proximal internal carotid thrombosis (OR, 3.29; 95% CI, 0.99 to 10.95; P=0.05). CONCLUSIONS: Our study confirms the safety of intravenous rtPA at a dose of 0.8 mg/kg and suggests efficacy for this drug even within 7 hours. Outcome and hematoma rates were at least as favorable as for trials of therapy with a 3-hour time window. Subgroups with a poor prognosis include low baseline neurological score, baseline CT changes, and proximal ICA thrombosis. However, approximately 30% of patients with each of these characteristics show a good outcome, so their inclusion in future routine rtPA protocols is still justified.

Adult↗

PubMed1998

The contractile apparatus of airway smooth muscle. Biophysics and biochemistry.

Qualitatively the mechanical, structural, and biochemical properties of airway smooth muscles resemble those of all other smooth muscle. However, one important distinguishing feature of airway smooth muscle is that the major portion of isotonic shortening is completed within the first 3 s in a muscle whose contraction is 10 s. This indicates the importance of focusing on the changes that occur in these 3 s and also the limiting role of the maximum velocity of shortening in determining shortening data. There is evidence that the maximum capacity and velocity of shortening in human bronchial smooth muscle from patients with asthma are significantly greater than those obtained from healthy siblings. In the demonstration in which cells in culture are arrested by withdrawing all fetal calf serum, the cells alter their phenotype to cells that are very long (more than 200 micrometers) and shorten twice as much as cells freshly isolated when the tissue is new. Speculatively, if such cells developed in vivo they could account for the increased contractility of asthmatic airway smooth muscle. These cultured cells could also be excellent models for study of airway smooth muscle contractility.

Animals↗

PubMed1998

Asymmetrical localization of mRNAs in enterocytes of human jejunum.

Intracellular localization of specific mRNAs is known to be a mechanism for targeting proteins to specific sites within the cell. Previous studies from this laboratory have demonstrated co-localization of mRNAs and proteins for a number of genes in absorptive enterocytes of fetal rat intestine. The present study was undertaken to examine in human enterocytes the intracellular localization patterns of mRNAs for the microvillous membrane proteins lactase-phlorizin hydrolase (LPH), sucrase-isomaltase (SI), and intestinal alkaline phosphatase (IAP), and the cytoskeletal protein beta-actin. In sections of human jejunum, mRNAs were localized by in situ hybridization using digoxigenin-labeled anti-sense RNA probes. Both LPH and SI mRNAs were localized to the apical region of villous enterocytes, whereas IAP and beta-actin mRNAs were detected both apically and basally relative to the nucleus. Therefore, in contrast to LPH, SI, and beta-actin mRNAs, which co-localize with their encoded proteins, that of IAP is present in the basal region of the cell where IAP protein has not directly been demonstrated to be present. Absorptive enterocytes from humans possess the mechanisms for intracellular mRNA localization, but not all mRNAs co-localize with their encoded proteins.

Actins↗

PubMed1998

Quantified EEG activity in adolescent attention deficit hyperactivity disorder.

The aim of this study was to explore elements of the maturational and cortical hypoarousal models in adolescent ADHD, by examining EEG activity in a rest eyes open condition, in 26 adolescent unmedicated ADHD males and 26 age and sex matched normal controls. ADHD adolescents were found to have increased anterior EEG absolute theta activity and reduced posterior relative beta activity compared with controls. These results lend some support to the continuation of a maturational lag and reduced cortical arousal in adolescent ADHD. These measures need to be further explored using concomitant EEG with electrodermal measures of arousal.

Adolescent↗

PubMed1998

Expression and regulation of interferon-gamma-inducible protein 10 gene in rat Leydig cells.

In the present study, we report the cloning of a gene that is differentially expressed in normal adult rat Leydig cells and whose expression is inhibited by hCG but is induced by interferon-gamma (IFNgamma). DNA sequence analysis identified this gene as rat IFNgamma-inducible protein 10 (IP-10), a member of the -C-X-C- chemokine superfamily of proinflammatory cytokines. High levels of IP-10 messenger RNA (mRNA) were constitutively expressed in freshly isolated and primary cultured Leydig cells. hCG inhibited this expression in a dose-dependent manner. The addition of 1 ng/ml hCG inhibited IP-10 mRNA levels more than 80%. Conversely, IP-10 mRNA levels were markedly increased in response to murine interleukin-1alpha, murine tumor necrosis factor-alpha, and murine IFNgamma by 3.3-, 10-, and 26-fold, respectively. Concomitant addition of murine interleukin-1alpha, murine tumor necrosis factor-alpha, and murine IFNgamma synergistically increased IP-10 mRNA levels by 58-fold. Furthermore, in addition to one previously described rat IP-10 mRNA transcript (1.5 kb), another larger transcript (2.7 kb) was identified by Northern blot in rat Leydig cells. After screening a rat testis complementary DNA library, we obtained a partial structural gene and an intron sequence, which possibly originated from the larger transcript of rat IP-10 mRNA. Histochemical and immunocytochemical staining revealed that purified cells were positive for 3beta-hydroxysteroid dehydrogenase and IP-10, confirming that IP-10 is indeed present in Leydig cells. IP-10 antisense oligonucleotides enhanced basal and hCG-induced testosterone formation. This suggests that endogenous IP-10 has an inhibitory effect on Leydig cell steroidogenesis. In conclusion, IP-10 is expressed in rat Leydig cells and may have paracrine and autocrine effects on testicular function.

Animals↗

PubMed1998

Progressive supranuclear gaze palsy is in linkage disequilibrium with the tau and not the alpha-synuclein gene.

We studied two candidate genes, tau (tau) and alpha-synuclein (SNCA), for evidence of linkage disequilibrium on a group of unrelated individuals with progressive supranuclear palsy (PSP) and a group of age-matched control subjects. The tau alpha1 allele and the tau alpha1alpha1 genotype were overrepresented in individuals with PSP and the tau polymorphism was in linkage disequilibrium with the PSP disease locus when a recessive inheritance model was employed. We also report a lack of evidence to support linkage disequilibrium between PSP and the SNCA candidate Parkinson's disease gene on chromosome 4q21-q23.

Aged↗

PubMed1998

Dual function of Ras in Raf activation.

The small guanine nucleotide binding protein p21(Ras) plays an important role in the activation of the Raf kinase. However, the precise mechanism by which Raf is activated remains unclear. It has been proposed that the sole function of p21(Ras )in Raf activation is to recruit Raf to the plasma membrane. We have used Drosophila embryos to examine the mechanism of Raf (Draf) activation in the complete absence of p21(Ras) (Ras1). We demonstrate that the role of Ras1 in Draf activation is not limited to the translocation of Draf to the membrane through a Ras1-Draf association. In addition, Ras1 is essential for the activation of an additional factor which in turn activates Draf.

Animals↗

PubMed1998

Study of interleukin-6 and tumor necrosis factor-alpha levels in maternal serum and amniotic fluid of patients with premature rupture of membranes.

To study the change and clinical significance of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) levels in the maternal serum and amniotic fluid of pregnant women with chorioamnionitis and with premature rupture of membranes. Twenty-six normal-term pregnant women formed the control group, and forty-six pregnant women with premature rupture of membranes were enrolled for the study. Maternal serum and amniotic fluid IL-6 and TNF-alpha levels were measured using a sensitive radioimmunoassay and enzyme-linked immunosorbent assay (ELISA); chorioamnionitis was diagnosed by fetal membrane pathology. The maternal serum IL-6 levels and amniotic fluid IL-6 and TNF-alpha levels were higher than those of the control (P < 0.01). There was a significant relationship between maternal serum IL-6 and maternal serum and amniotic fluid IL-6 and TNF-alpha with the time of the premature rupture of membranes, i.e. the longer the time, the higher the maternal serum and amniotic fluid IL-6 and TNF-alpha. There were 12 patients with chorioamnionitis in premature rupture of membranes and their maternal serum and amniotic fluid IL-6 and TNF-alpha levels were higher than that of non-chorioamnionitis patients (P < 0.01-0.05). IL-6 and TNF-alpha levels in maternal and amniotic fluids are a valuable index in identification of the chorioamnionitis in patients with premature rupture of membranes.

Adult↗