Effects of exposure to organic solvents on menstrual cycle length

To investigate the association between organic solvent exposure and menstrual disturbance, we conducted a cross-sectional study among 1408 petrochemical workers in China. Based on an industrial hygiene evaluation, we classified the workshops according to the presence or absence of organic solvents (benzene, styrene, toluene, or xylene). We used logistic regression to estimate odds ratios and 95% confidence intervals for prolonged menstrual cycle length (oligomenorrhea: average cycle length > 35 days during the previous year) associated with the exposure. After adjustment for confounders, each additional year of work in an exposed workshop was associated with a 7% increase in oligomenorrhea (odds ratio, 1.07; 95% confidence interval, 1.00 to 1.14). Compared with no exposure, 3 or more years of exposure was associated with a 53% increase in oligomenorrhea (odds ratio, 1.53; 95% confidence interval, 1.00 to 2.34). We concluded that exposure to organic solvents is associated with a trend toward increased frequency of oligomenorrhea.

Identification and implantation stage-specific expression of an interferon-alpha-regulated gene in human and rat endometrium

Implantation of the developing blastocyst is regulated by multiple effectors, such as steroid hormones, growth factors, and cytokines. To understand how these diverse signaling pathways interact to modulate uterine gene expression, we employed a gene expression screen technique to identify the molecules that are induced in the periimplantation rat uterus. Here we report the isolation of a complementary DNA representing a novel gene, interferon-regulated gene 1 (IRG1). This gene exhibits significant homology to interferon (IFN)-alpha/beta-inducible human genes p27 and 6-16, indicating that these genes may belong to the same family. Consistent with this finding, expression of IRG1 messenger RNA (mRNA) in rat uterus increased about 20-fold in response to IFNalpha. Uterine expression of IRG1 was also stimulated by estrogen and was partially inhibited by an antiestrogen, ICI 182,780. In pregnant rats, IRG1 expression was high on day 1, but declined on days 2 and 3. The level of IRG1 mRNA again rose transiently on day 4 immediately preceding implantation. In situ hybridization analysis localized the IRG1 mRNA expression in the endometrial epithelium and the surrounding stroma. Interestingly, the expression of p27, which shows high homology to IRG1, was strongly enhanced in human endometrium during the midsecretory phase of the menstrual cycle, overlapping the putative window of implantation. Both IRG1 and p27 mRNAs are therefore induced in the endometrium in an implantation stage-specific manner. We also observed a synergistic interaction between IFNalpha and estrogen receptor signaling pathways that led to maximal induction of p27 mRNA in Ishikawa cells. Although the functional roles of IRG1 and p27 remain unclear, we describe for the first time, identification of a gene family regulated by IFNalpha in both rodent and human uteri. More importantly, our studies reveal that a complex interplay between the steroid hormone and IFN pathways regulates the expression of these genes in the endometrium at the time of implantation.

[Monte Carlo simulation of FCS in a laser gradient field]

Fluorescence correlation spectroscopy (FCS) is a powerful tool for probing biological process inside living cells. It measures fluorescence fluctuations of small number of molecules and derive information on molecular kinetics and reactions. We have developed a Monte Carlo model to simulate Browning motion of Rayleigh particles in a laser gradient field. The simulation reveals relations between laser field strength and measured parameters from FCS, such as diffusion coefficient and number density of the particles. The simulated results agree qualitatively to the experimental results obtained using fluorescent spheres. Empirical relations from the simulation are also discussed.

[The cytotoxic effects of the adriamycin magnetic albumin microspheres combined with external magnetic fields on the malignant tumor cells]

This study sought to assess the inhibitory effects of the adriamycin magnetic albumin microspheres (ADM-MAMs) on Walker-256 malignant tumor cells in vitro induced by the permanent magnetic fields. The cultured Walker-256 cells were divided into three groups; the group of ADM-MAMs combined with magnetic fields, the group of AMD-MAMs without magnetic fields, and ADM group. The growth states of the cells were observed and photographed under the inverted microscope. The inhibitory rates(IR) were assayed by the modified MTT colorimetric method. The results showed that the IR of the ADM-MAMs group were similar to those of the ADM group (P > 0.05), but the group of ADM-MAMs combined with magnetic fields had obviously higher IR and significant changes of the cells' shapes. These findings indicate that the anticancer effect of ADM-MAMs on malignant tumor cells is similar to that of ADM, and such effect can be increased by the combined use of ADM-MAMs and external magnetic fields.

[Analysis of the lineshape of laser frequency modulation]

In this paper, we analyze the dependence of the output signal spectral lineshape and intensity on the modulation, waveform and modulation index in first- and second-harmonic detection of triangle modulation, square demodulation and saw modulation square demodulation. The signal lineshape in the case of saw modulation, square demodulation is quite different from, whereas the signal lineshape in the case of triangle modulation, square demodulation is similar to that in traditional sine modulation, sine demodulation. Experiments of tunable IR laser frequency modulation absorption spectrum of methane are also done to verify the theoretical analysis. Then we reach a conclusion; the lineshape and intensity of frequency modulation spectrum can be influenced by modulation waveform, demodulation waveform and modulation index. Calculation results can be used to choose better experimental parameters and optimize experimental designs.

Global ischemia induces expression of acid-sensing ion channel 2a in rat brain

Acid-sensing ion channels (ASICs) are ligand-gated cation channels that respond to acidic stimuli. They are expressed throughout the mammalian nervous system. In the peripheral nervous system, ASICs act as nociceptors, responding to the tissue acidosis that accompanies ischemic and inflammatory conditions. The function of ASICs in the central nervous system is not known. In this article, the authors present evidence that transient global ischemia induces ASIC 2a protein expression in neurons that survive ischemia. Western blot analysis with an anti-ASIC 2a antibody revealed up-regulation of an 80 kD protein in ischemic rat brain. Immunohistochemical analysis showed that ASIC 2a protein expression increased in neurons of the hippocampus and cortex. Klenow fragment-mediated labeling of DNA strand breaks determined that ASIC 2a induction did not occur in cells with detectable DNA damage. The current results suggest a possible role for ASICs in mediating a cellular response to ischemia.

[Synthesis of nanocrystalline Y2O3:Eu3+ and study on spectral characteristics]

Nano-Y2O3:Eu3+ was synthesized with oxalic acid as precipitate agent while adding little surfactant controlling the condition of the reaction. We obtained nanoscale powder. The particle diameter was 15-19 nm. The agglomerate size was less 1.0 micron. Compared with the ordinary powder of Y2O3:Eu3+, the peak of emission spectrum of nano-Y2O3:Eu3+ is at lambda em = 612 nm under 254 nm excitation, blue-shift 6 nm. Excitation spectrum has no difference. The phosphor was measured by PMS-3 chromatic detector and its luminescent chromatic coordinate parameters were x = 0.6479, y = 0.3442. The quenching concentration increases from micro-Y2O3:Eu3+'s 6% to 9% and the intensity of luminescence increases with the grain size growing.

Methylation of histone H3 by coactivator-associated arginine methyltransferase 1

The preferential in vitro methylation of histone H3 by coactivator-associated arginine methyltransferase 1 (CARM1) has been proposed as a basis for its ability to enhance gene transcription [Chen, D., et al. (1999) Science 284, 2174-2177]. To further evaluate the significance of H3 methylation, we studied the kinetics and site specificity of its modification by CARM1. Affinity-purified CARM1 methylated recombinant chick H3, which is free of posttranslational modifications, and calf thymus H3, which is heterogeneous with regard to preexisting modifications, equally well, exhibiting a V(max) of 4500 pmol min(-1) (mg of enzyme)(-1) and an apparent K(m) for H3 of < or = 0.2 microM. The catalytic efficiency (k(cat)/K(m)) of CARM1 toward H3 was at least 1000 times that toward R1 (GGFGGRGGFGG-amide), a highly effective substrate for protein arginine methyltransferase 1. Peptide mapping of 3H-methyl-labeled H3 indicated methylation at Arg-2, Arg-17, and Arg-26 in the N-terminal region and at one or more of four arginines (128/129/131/134) at the C-terminus. Two of the N-terminal sites, Arg-17 and Arg-26, occur in the sequence KAXRK and appear to be more efficiently methylated than Arg-2. CARM1 catalyzed formation of N(G),N(G)-dimethylarginine (asymmetric) but little or no N(G),N'(G)-dimethylarginine (symmetric) and no form of methyllysine. Amino acid analysis of untreated calf thymus H3 revealed that 3.7% of the molecules naturally contain asymmetric dimethylarginine and/or monomethylarginine. Our findings support the hypothesis that methylation of H3 may be involved in the mechanism of transcriptional coactivation by CARM1 of genes whose expression is under the control of nuclear receptors.

CD44-deficient mice exhibit enhanced hepatitis after concanavalin A injection: evidence for involvement of CD44 in activation-induced cell death

Administration of Con A induces severe injury to hepatocytes in mice and is considered to be a model for human hepatitis. In the current study, we investigated the role of CD44 in Con A-induced hepatitis. Intravenous administration of Con A (20 mg/kg) caused 100% mortality in C57BL/6 CD44-knockout (KO) mice, although it was not lethal in C57BL/6 CD44 wild-type (WT) mice. Administration of lower doses of Con A (12 mg/kg body weight) into CD44 WT mice induced hepatitis as evident from increased plasma aspartate aminotransferase levels accompanied by active infiltration of mononuclear cells and neutrophils, and significant induction of apoptosis in the liver. Interestingly, CD44 KO mice injected with similar doses of Con A exhibited more severe acute suppurative hepatitis. Transfer of spleen cells from Con A-injected CD44 KO mice into CD44 WT mice induced higher levels of hepatitis when compared with transfer of similar cells from CD44 WT mice into CD44 WT mice. The increased hepatitis seen in CD44 KO mice was accompanied by increased production of cytokines such as TNF-alpha, IL-2 and IFN-gamma, but not Fas or Fas ligand. The increased susceptibility of CD44 KO mice to hepatitis correlated with the observation that T cells from CD44 KO mice were more resistant to activation-induced cell death when compared with the CD44 WT mice. Together, these data demonstrate that activated T cells use CD44 to undergo apoptosis, and dysregulation in this pathway could lead to increased pathogenesis in a number of diseases, including hepatitis.

Reactive oxygen species involved in trichosanthin-induced apoptosis of human choriocarcinoma cells

The type-I ribosome-inactivating protein trichosanthin (TCS) has a broad spectrum of biological and pharmacological activities, including abortifacient, anti-tumour and anti-HIV activities. We have found for the first time that TCS stimulated the production of reactive oxygen species (ROS) in JAR cells (a human choriocarcinoma cell line) in a time- and concentration-dependent manner by using the fluorescent probe 2',7'-dichlorofluorescein diacetate with confocal laser scanning microscopy. ESR spectral studies and the inhibition of ROS formation by the superoxide radical anion (O(2)(-.)) scavenger superoxide dismutase, the H(2)O(2) scavenger catalase and the hydroxyl radical (OH(.)) scavenger mannitol suggested the involvement of O(2)(-.), H(2)O(2) and OH(.). TCS-induced ROS formation was shown to be dependent on the presence of both extracellular and intracellular Ca(2+); moreover, ROS production paralleled the intracellular Ca(2+) elevation induced by TCS, suggesting that ROS production might be a consequence of Ca(2+) signalling. TCS-induced activation of caspase-3 was initiated within 2 h; however, TCS-induced production of ROS was initiated within 5 min, suggesting that the production of ROS preceded the activation of caspase-3. Simultaneous observation of the nuclear morphological changes via two-photon laser scanning microscopy and ROS production via confocal laser scanning microscopy revealed that ROS is involved in the apoptosis of JAR cells. The involvement of ROS was also confirmed by the inhibition of TCS-induced cell death by the antioxidant Trolox and the ROS scavengers catalase and mannitol. Diethylenetriaminepenta-acetic acid, an inhibitor of metal-facilitated OH(.) formation, markedly inhibited TCS-induced cell death, suggesting that TCS induced OH(.) formation via the Fenton reaction. The finding that ROS is involved in the TCS-induced apoptosis of JAR cells might provide new insight into the anti-tumour and anti-HIV mechanism of TCS.

Diagnosis and treatment of bronchial rupture from blunt thoracic trauma

OBJECTIVE

To evaluate the diagnosis and management of bronchial rutpture from blunt thoracic trauma.

METHODS

A group of 31 patients with bronchial rupture was involved. Chest roentgenography, tomography and bronchoscopy were performed on all patients. The surgical technique and complications were described.

RESULTS

Diagnosis was confirmed by tomography and bronchoscopy in all the patients. End to end anastomosis was used in 26 patients. Four patients were operated with total pneumonectomy. One patient was repaired with an intercostal muscle and rib flap with blood supply. Of the 31 patients, one died of adult respiratory distress syndrome after operation. Most patients had excellent surgical outcomes. 81% (25/31) of the bronchial rupture were delayed in diagnosis and treatment. The classic symptoms and signs of bronchial rupture included subcutaneous emphysema, dyspnea and an intermediate coma interval. The roentgenogram showed mediastinal emphysema, pneumothorax, "drop lung" sign and marked radiodensity of hilum widened mediastinum.

CONCLUSION

Bronchoscopy is a useful and accurate method to diagnose and treat the bronchial rupture, with which surgeons can easily locate the rupture site during surgery. Surgical treatment could restore pulmonary function in most patients.

Heterotopic cervical pregnancy successfully treated with transvaginal ultrasound-guided aspiration and cervical-stay sutures

OBJECTIVE

To present a case of a heterotopic cervical pregnancy successfully treated with transvaginal ultrasound-guided aspiration and cervical-stay sutures.

DESIGN

Case report.

SETTING

Tertiary academic IVF program.

PATIENT(S)

A 35-year-old woman who conceived from IVF-ET treatment at 5.5 weeks of gestation.

INTERVENTION(S)

Transvaginal ultrasound-guided aspiration of the cervical pregnancy followed by cervical-stay sutures to control hemorrhage after aspiration.

MAIN OUTCOME MEASURE(S)

Recovery of the patient, preservation of the intrauterine pregnancy, and sequelae.

RESULTS(S)

The cervical pregnancy was successfully aborted, and the intrauterine pregnancy progressed to term.

CONCLUSION(S)

Transvaginal ultrasound-guided aspiration in combination with hemostatic cervical-stay sutures can be safely used to manage heterotopic cervical pregnancies.

Ovine caveolin-1: cDNA cloning, E. coli expression, and association with endothelial nitric oxide synthase

Caveolin-1 (Cav-1), the principal coat protein of caveolae, plays an obligatory role in regulating the activity of endothelial nitric oxide (NO) synthase (eNOS). We propose that Cav-1 may be critical to eNOS-NO mediated uterine vasodilatation during pregnancy and estrogen replacement therapy. To test this hypothesis in the sheep model, we isolated the full-length cDNA of ovine Cav-1 (oCav-1) from a Lambda ZAP cDNA library of ovine placental artery endothelial cells. Thirty-two positive oCav-1 clones were recognized by a partial oCav-1 cDNA from this library, of which eight were sequenced. Restriction digestion of these clones revealed that the cDNAs of oCav-1 ranged from approximately 2.1 to 2.7 kb. Northern analysis of Cav-1 mRNAs in ovine uterine artery endothelial cells (UAEC) showed two transcripts of approximately 2.1 and 2.7 kb, respectively. Immunoreactive Cav-1 protein, but not caveolin-2 or caveolin-3, was detected in UAEC. Sequence analysis revealed that in addition to a 537-bp open reading frame encoding a 178 amino acid oCav-1 protein, full-length oCav-1 cDNAs apparently possess a approximately 1.6-2.1 kb 3'-untranslated region. Database searches with oCav-1 cDNA revealed that the coding region of mammalian Cav-1 genes is highly conserved. We prepared a recombinant full-length oCav-1 protein in which six consecutive histidine residues were tagged at the end of its COOH-terminus and developed a [His]6-tagged oCav-1 'pull-down assay' for studying the association of eNOS with Cav-1. Incubation of exogenous [His]6-tagged oCav-1 with resting UAEC extracts led to the formation of a [His]6-tagged oCav-1-eNOS complex. In the presence of a synthetic caveolin-scaffolding domain (CSD, aa 82-101) peptide, but not a mutated CSD peptide, [His]6-tagged oCav-1 associated eNOS was dose (0-10 microM)-dependently inhibited. eNOS association with Cav-1 in UAEC was further confirmed by the facts that eNOS co-immunoprecipitated with Cav-1 and vice versa, and that eNOS co-existed with Cav-1 during the isolation of caveolae membranes. Because dissociation of eNOS from Cav-1 is required for the activation of eNOS, eNOS association with Cav-1 in UAEC suggests an important role of Cav-1 in regulating UAEC production of NO and possibly NO-mediated uterine vasodilatation.

Gaf-1, a gamma -SNAP-binding protein associated with the mitochondria

The role of alpha/beta-SNAP (Soluble NSF Attachment Protein) in vesicular trafficking is well established; however, the function of the ubiquitously expressed gamma-SNAP remains unclear. To further characterize the cellular role of this enigmatic protein, a two-hybrid screen was used to identify new, gamma-SNAP-binding proteins and to uncover potentially novel functions for gamma-SNAP. One such SNAP-binding protein, termed Gaf-1 (gamma-SNAP associate factor-1) specifically binds gamma- but not alpha-SNAP. The full-length Gaf-1 (75 kDa) is ubiquitously expressed and is found stoichiometrically associated with gamma-SNAP in cellular extracts. This binding is distinct from other SNAP interactions since no alpha-SNAP or NSF coprecipitated with Gaf-1. Subcellular fractionation and immunofluorescence analysis show that Gaf-1 is peripherally associated with the outer mitochondrial membrane. Only a fraction of gamma-SNAP was mitochondrial with the balance being either cytosolic or associated with other membrane fractions. GFP-gamma-SNAP and the C-terminal domain of Gaf-1 both show a reticular distribution in HEK-293 cells. This reticular structure colocalizes with Gaf-1 and mitochondria as well as with microtubules but not with other cytoskeletal elements. These data identify a class of gamma-SNAP interactions that is distinct from other members of the SNAP family and point to a potential role for gamma-SNAP in mitochondrial dynamics.

Features of the 3'-consensus sequence of rotavirus mRNAs critical to minus strand synthesis

The last seven nucleotides of the 3'-end of rotavirus mRNAs, 5'-UGUGACC-3', are highly conserved and form a cis-acting signal that can promote the synthesis of (-) strand RNA to produce the viral dsRNA genome in vitro. Previous studies have shown that the sequence, location, and strandedness (single- versus double-stranded) of the 3'-consensus sequence of the mRNA affect the efficiency of (-) strand synthesis. In this study, we have used exhaustive mutagenesis of the SA11 gene 8 mRNA and an in vitro replication system to define the importance of each of the residues in the consensus sequence in (-) strand synthesis. The analysis showed that the CC of the consensus sequence was the most critical for (-) strand synthesis. Furthermore, the data revealed that other, but not all, residues of the consensus sequence contributed to efficient (-) strand synthesis in vitro. Mutant gene 8 RNAs supported an intermediate level of (-) strand synthesis when the 15 nt sequence upstream of the CC was replaced with long tracts of poly(A) or poly(U), but not with poly(G). Predictions of the secondary structure of the mutant RNAs suggested that the poly(G)-RNA could not replicate because its 3'-terminus was largely basepaired, instead of extending as a single-stranded tail as is the case for the 3'-termini of the poly(A)- and poly(U)-RNAs and wild-type gene 8 RNA. Subsequent experiments performed with complementary oligonucleotides indicated that efficient RNA replication occurs in vitro only when the last four residues of the 3'-consensus sequence, and most importantly the two terminal C's, existed in a single-stranded form. A single-stranded CC may be crucial for formation of an initiation complex for (-) strand synthesis consisting of viral RdRP, mRNA, and the dinucleotide pGpG.

Adjuvantation of epidermal powder immunization

The skin is an immunologically active site and an attractive vaccination route. All current vaccines, however, are administered either orally, intramuscularly, or subcutaneously. We previously reported that epidermal powder immunization (EPI) with an extremely small dose of powdered influenza vaccine induces protective immunity in mice. In this study, we report that commonly used adjuvants can be used in EPI to further enhance the immune responses to an antigen. The IgG antibody response to diphtheria toxoid (DT) following EPI was augmented by 25- and 250-fold, when 1 microg DT was co-delivered with aluminum phosphate (alum) and a synthetic oligonucleotide containing CpG DNA motifs (CpG DNA), respectively. These antibodies had toxin-neutralization activity and were long lasting. Furthermore, EPI using an adjuvant selectively activated different subsets of T helper cells and gave either a Th1 or a Th2 type of immune response. Similar to needle injection into deeper tissues, EPI with alum adsorbed DT promoted a predominantly IgG1 subclass antibody response and elevated level of IL-4 secreting cells. These are indicative of Th2-type immunity. In contrast, co-delivery of CpG DNA adjuvant via EPI led to Th-1 type of response as characterized by the increased production of IgG2a antibodies and IFN-gamma secreting cells. This study indicated that EPI using appropriate adjuvants can produce an augmented antibody response and desirable cellular immune responses. EPI is a promising immunization method that may be used to administer a broad range of vaccines including vaccines with adjuvants.

Endothelin-1 initiates the development of vasospasm after subarachnoid haemorrhage through protein kinase C activation, but does not contribute to prolonged vasospasm

Endothelium plays a role in the regulation of vascular tone. Endothelin is a family of potent vasoconstrictive peptides, and endothelin-1 (ET-1) produced in the endothelium induces a tonic contraction via specific receptor ET(A). ET-1 has been postulated as an important factor in the development of vasospasm after subarachnoid haemorrhage (SAH). We have previously shown that protein kinase C (PKC) of the cerebral artery plays a pivotal role in the pathogenesis of vasospasm. The purpose of this study is to clarify the relationship between ET-1 and PKC in the development and maintenance of vasospasm. Using a "two-haemorrhage" canine model, chronological changes of angiographic progression of vasospasm, PKC activation, and ET-1 level of the basilar artery were assessed. In an isometric tension study with a control artery, the effects of ET(A)- and ET(A)/ET(B)-antagonists on the tonic contraction induced by ET-1 were examined. The effects of ET-1, ET-1 and an ET(A)-antagonist, and ET-1 and an ET(A)/ET(B)-antagonist on PKC activation were also evaluated. ET-1 level temporarily increased, then decreased to the control level in a later stage of vasospasm. ET-1 induced a tonic contraction and enhancement of PKC activation, but both were inhibited either by an ET(A)- or an ET(A)/ET(B)-antagonist. These results indicate that ET-1 initiates the development of vasospasm through PKC activation, but does not contribute to prolonged vasospasm.

Intracellular Bax translocation after transient cerebral ischemia: implications for a role of the mitochondrial apoptotic signaling pathway in ischemic neuronal death

Activation of terminal caspases such as caspase-3 plays an important role in the execution of neuronal cell death after transient cerebral ischemia. Although the precise mechanism by which terminal caspases are activated in ischemic neurons remains elusive, recent studies have postulated that the mitochondrial cell death-signaling pathway may participate in this process. The bcl-2 family member protein Bax is a potent proapoptotic molecule that, on translocation from cytosol to mitochondria, triggers the activation of terminal caspases by increasing mitochondrial membrane permeability and resulting in the release of apoptosis-promoting factors, including cytochrome c. In the present study, the role of intracellular Bax translocation in ischemic brain injury was investigated in a rat model of transient focal ischemia (30 minutes) and reperfusion (1 to 72 hours). Immunochemical studies revealed that transient ischemia induced a rapid translocation of Bax from cytosol to mitochondria in caudate neurons, with a temporal profile and regional distribution coinciding with the mitochondrial release of cytochrome c and caspase-9. Further, in postischemic caudate putamen in vivo and in isolated brain mitochondria in vitro, the authors found enhanced heterodimerization between Bax and the mitochondrial membrane permeabilization-related proteins adenine nucleotide translocator (ANT) and voltage-dependent anion channel. The ANT inhibitor bongkrekic acid prevented Bax and ANT interactions and inhibited Bax-triggered caspase-9 release from isolated brain mitochondria in vitro. Bongkrekic acid also offered significant neuroprotection against ischemia-induced caspase-3 and caspase-9 activation and cell death in the brain. These results strongly suggest that the Bax-mediated mitochondrial apoptotic signaling pathway may play an important role in ischemic neuronal injury.

Performance of time-frequency representation techniques to measure blood flow turbulence with pulsed-wave Doppler ultrasound

The current processing performed by commercial instruments to obtain the time-frequency representation (TFR) of pulsed-wave Doppler signals may not be adequate to characterize turbulent flow motions. The assessment of the intensity of turbulence is of high clinical importance and measuring high-frequency (small-scale) flow motions, using Doppler ultrasound (US), is a difficult problem that has been studied very little. The objective was to optimize the performance of the spectrogram (SPEC), autoregressive modeling (AR), Choi-Williams distribution (CWD), Choi-Williams reduced interference distribution (CW-RID), Bessel distribution (BD), and matching pursuit method (MP) for mean velocity waveform estimation and turbulence detection. The intensity of turbulence was measured from the fluctuations of the Doppler mean velocity obtained from a simulation model under pulsatile flow. The Kolmogorov spectrum, which is used to determine the frequency of the fluctuations and, thus, the scale of the turbulent motions, was also computed for each method. The best set of parameters for each TFR method was determined by minimizing the error of the absolute frequency fluctuations and Kolmogorov spectral bandwidth measured from the simulated and computed Doppler spectra. The results showed that different parameters must be used for each method to minimize the velocity variance of the estimator, to optimize the detection of the turbulent frequency fluctuations, and to estimate the Kolmogorov spectrum. To minimize the variance and to measure the absolute turbulent frequency fluctuations, four methods provided similar results: SPEC (10-ms sine-cosine windows), AR (10-ms rectangular windows, model order = 8), CWD (w(N) and w(M) = 10-ms rectangular windows, sigma = 0.01), and BD (w(N) = 10-ms rectangular windows, alpha = 16). The velocity variance in the absence of turbulence was on the order of 0.04 m/s (coefficient of variation ranging from 8.0% to 14.5%, depending on the method). With these spectral techniques, the peak of the turbulence intensity was adequately estimated (velocity bias < 0.01 m/s). To track the frequency of turbulence, the best method was BD (w(N) = 2-ms rectangular windows, alpha = 2). The bias in the estimate of the -10 dB bandwidth of the Kolmogorov spectrum was 354 +/- 51 Hz in the absence of turbulence (the true bandwidth should be 0 Hz), and -193 +/- 371 Hz with turbulence (the simulated -10-dB bandwidth was estimated at 1256 Hz instead of 1449 Hz). In conclusion, several TFR methods can be used to measure the magnitude of the turbulent fluctuations. To track eddies ranging from large vortex to small turbulent fluctuations (wide Kolmogorov spectrum), the Bessel distribution with appropriate set of parameters is recommended.

Co-operation between protein-acetylating and protein-methylating co-activators in transcriptional activation

Nuclear hormone receptors (NRs) activate transcription by binding to specific enhancer elements associated with target genes. Transcriptional activation is accomplished with the help of complexes of co-activator proteins that bind to NRs. p160 co-activators, a family of three related 160 kDa proteins, serve as primary co-activators by binding directly to NRs and recruiting additional secondary co-activators. Some of these (CBP/p300 and p/CAF) can acetylate histones and other proteins in the transcription complex, thus helping to modify chromatin structure and form an active transcription initiation complex. We recently discovered co-activator-associated arginine methyltransferase 1 (CARM1), which binds to p160 co-activators and thereby enhances transcriptional activation by NRs on transiently transfected reporter genes. CARM1 also methylates specific arginine residues in the N-terminal tail of histone H3 in vitro. A related arginine-specific protein methyltransferase, PRMT1, also binds p160 co-activators and enhances NR function. PRMT1 methylates histone H4 in vitro. The enhancement of NR function by CARM1, PRMT1 and p300 depends on their interactions with p160 co-activators. In the presence of p160 co-activators, some pairs of these three secondary co-activators provide a highly synergistic enhancement of NR function on transiently transfected reporter genes. We have also observed an enhancement of NR function on stably integrated reporter genes by these co-activators. We propose that the synergy of co-activator function between p300, CARM1 and PRMT1 is due to their different but complementary protein modification activities.

Postprandial cell proliferation in the esophageal epithelium of rats

Food intake is known to trigger cell growth in the mucosa of several gut segments. In this study, the effects of both oral feeding and intragastric feeding on cell proliferation in the esophageal epithelium of rats were examined. A similar study was carried out in antrectomized animals. Refeeding of fasted rats either orally or through an intragastric catheter increased the esophageal epithelial labeling index (LI) 310 and 445%, respectively, while the mitotic index (MI) increased 427 and 217%, respectively. Under the same experimental settings, the serum gastrin values increased 423 and 200%, respectively. After surgical resection of the antrum, a postprandial proliferative wave was still observed in the orally fed rats, with an increase in LI and MI of 114 and 166%, but not in the animals refed through the gastrostomy. This study demonstrates the growth stimulating effect of feeding on the rat esophageal epithelium. This effect appears to be triggered by the mechanical passage of food and the antral release of a systemic factor, which is most probably gastrin.

Reverse transcriptase adds nontemplated nucleotides to cDNAs during 5'-RACE and primer extension

In determining the terminal sequences of the genomic dsRNAs of rotavirus by 5'-rapid amplification of cDNA ends (5'-RACE), it was found that most of the viral cDNAs contained extra nucleotides at their 5' termini that had not been reported before on any rotavirus sequence. Although the extra nucleotides could be dA, dC, dG, or dT residues, the extra nucleotides on the cDNAs usually consisted of a single dT residue. Experiments performed with DNA/RNA duplexes indicated that reverse transcriptase has an associated terminal nucleotidyl transferase (TdT)-like activity, which can add nontemplated nucleotides to the 3' ends of DNA, and that reverse transcriptase was responsible for the presence of the extra nucleotides detected on the 5'-RACE cDNAs. The TdT-like activity of reverse transcription was specific for double-stranded substrates (i.e., DNA/DNA or DNA/RNA duplexes) and was active over a wide range of temperatures and enzyme concentrations. Both commercially available Moloney murine leukemia virus and avian myeloblastosis virus reverse transcriptases contained the TdT-like activity. This work implies that 5'-RACE and primer extension assays must be used carefully in determining the terminal sequences of nucleic acids because, under standard reaction conditions, reverse transcriptase can add nontemplated nucleotides to the 3' ends of cDNAs following template-directed synthesis.

Cloning, expression, purification, and characterization of rat MMP-12

Macrophage metalloelastase (MMP-12) is implicated in the pathology of many diseases such as emphysema, aortic lesions and cancer. Recently, MMP-12 was cloned and purified from mouse and human macrophages. We report here the expression of the full-length and catalytic domain of rat MMP-12 in Escherichia coli and characterization of the purified enzyme. Inclusion bodies of expressed rat MMP-12 catalytic domain were denatured and refolded using a new method, and then affinity purified to near homogeneity with zinc-chelating Sepharose. The purified rat MMP-12 catalytic domain was highly active in digesting substrates, having a K(m) of 12 microM and optimal pH of 7.5--8.5. During investigation of natural substrate specificity, we found that rat MMP-12 catalytic domain was able to completely degrade collagen-V, partially degrade collagen-I, but it was unable to digest collagen-IV. The enzyme could also degrade osteonectin, vitronectin, and fibronectin, but not laminin and albumin. The catalytic properties and natural substrate specificity of rat MMP-12 catalytic domain differed from those of human MMP-12 catalytic domain.