Somatic mutations of fibroblast growth factor receptor 3 (FGFR3) are uncommon in carcinomas of the uterine cervix

Germline mutations of the gene encoding human fibroblast growth factor receptor 3 (FGFR3) have been shown to be responsible for several related autosomal dominant forms of syndromic craniosynostosis and short limb dwarfism. Somatic activating mutations of FGFR3 were recently reported to occur in three of 12 (25%) uterine cervical carcinomas and nine of 26 (35%) bladder carcinomas, suggesting that constitutive activation of FGFR3 may be an important mechanism underlying the development and/or progression of these common epithelial malignancies. In order to investigate further a possible role for FGFR3 mutations in cervical carcinogenesis, we performed sequence-based mutational analysis of FGFR3 in 51 primary cervical carcinomas and seven cervical carcinoma-derived cell lines. The regions analysed (exons 7, 10, 13, 15, and 19) encompassed all previously described FGFR3 mutations. A single nucleotide substitution at codon 249, predicting a serine to cysteine amino acid substitution (S249C) in the FGFR3 extracellular domain, was identified in one primary tumor. Only wild type FGFR3 alleles were identified in the remaining tumors and cell lines. The S249C mutation is the only FGFR3 mutation described to date in cervical carcinomas. These findings suggest that while activating mutations of FGFR3 occur in cervical cancer, they may not be as common as initially reported.

Single strand conformation polymorphism analysis of K-ras gene mutations by capillary electrophoresis with laser-induced fluorescence (LIF) detector

Mutations of K-ras gene play an important role in neoplastic progression. The capillary electrophoresis-single strand conformation polymorphism (CE-SSCP) technique is available for the detection of gene mutations. Using an automated capillary electrophoresis with short-chain linear polyacrylamide, after denaturation of PCR products, injections were performed at reverse polarity of 5 kV for 15 s and the separations were carried out under a constant voltage of 8 kV. Of 16 specimens of lung cancer tissue, two specimens were found to have abnormal peaks in the electrophoretogram. CE-SSCP is rapid, automated, and has high performance.

Phorbol ester-induced expression of airway squamous cell differentiation marker, SPRR1B, is regulated by protein kinase Cdelta /Ras/MEKK1/MKK1-dependent/AP-1 signal transduction pathway

The transcriptional induction of SPRR1B by phorbol 12-myristate 13-acetate (PMA) is mainly mediated by the first -152-base pair 5'-flanking region containing two functional AP-1 sites. In this study, we have analyzed the signaling pathways that mediate the induction in tracheobronchial epithelial cells. PKC inhibitor ablated PMA-stimulated expression of endogenous SPRR1B and reporter gene expression driven by SPRR1B promoter. PKC activator promoted the transcription. The dominant negative protein kinase Cdelta (dn-PKCdelta) and rottlerin (PKCdelta inhibitor) completely suppressed PMA-stimulated promoter activity. dn-Ras or dn-MEKK1 inhibited PMA-stimulated promoter activity, while their corresponding constitutively active mutants augmented it. dn-c-Raf-1 did not have any effect on reporter gene expression. Since MEKK1 activates multiple parallel pathways, we examined involvement of JNK/SAPK, p38, and MKK1 in promoter regulation. Co-expression of the dominant negative forms of MKK4, MKK7, JNK/SAPK, MKK3, MKK6, or p38alpha did not suppress PMA-stimulated reporter gene expression. However, MKK1 inhibitors UO126 and PD98095 suppressed gene expression. Consistent with this, expression of dn-MKK1 strongly suppressed PMA-stimulated promoter activity, while the constitutively active MKK1 augmented it. However, MKK1-mediated induction of SPRR1B probably does not depend on extracellular signal-regulated kinases 1 and 2, suggesting the requirement of another kinase(s). dn-c-Jun mutants abolished PMA-stimulated expression supporting an important role for AP-1 proteins in SPRR1B expression. Together, these results suggest that a PKCdelta/Ras/MEKK1/MKK1-dependent/AP-1 pathway regulates the PMA-inducible expression of the SPRR1B in tracheobronchial epithelial cells.

A comprehensive approach for accurate measurement of proton-proton coupling constants in the sugar ring of DNA

Stereo-selectivedeuteration has been explored as an approach for improving the accuracy of NMR-derived, three-bond vicinal proton-proton coupling constants in the 12-base-pair DNA Dickerson sequence [d(CGCGAATTCGCG)(2)]. The coupling constants are useful for DNA structure determination in restrained molecular dynamics calculations. Specifically, the A5 and A6 residues were prepared with the H2" proton stereo-selectively replaced with a deuteron. Deuteration of the H2" leads to a 42-fold reduction in the transverse cross-relaxation rate of the H2' spin, effectively negating the contribution of transverse cross relaxation to the cross peak frequencies and phases. Calculated linewidth and polarization transfer functions indicated that the reduced dipolar interaction is also expected to result in a significant increase in intensity for all cross peaks involving the H1', H2', or H3' spin. The spectral complexity is also reduced by selective deuteration. Time-shared homonuclear decoupling of passive spins during acquisition was implemented, reducing the spin system, in some cases, to an effectively isolated two-spin system. This enables the use of a 90 degrees mixing pulse instead of the 35 degrees pulse commonly used in standard P.E.COSY experiments, leading to an additional 75% increase in signal intensity. Selective excitation pulses were used to reduce the number of increments required in the indirect dimension by as much as a factor of 4. The cumulative improvement in sensitivity is striking, approaching three orders of magnitude per unit time. Separate experiments, referred to as Stripe-COSY and Superstripe-COSY, were optimized for each coupling constant measured. Finally, J-doubling was used to obtain the most accurate peak separations. This comprehensive approach shows promise as an effective method for extracting highly accurate homonuclear vicinal coupling constants in DNA.

[Some differences on biological characteristics of Campylobacter jejuni]

Fecal samples from 195 diarrheic patients in different age, rectal and cloacal swabs from 656 normal and diarrheic animals and poultry, 108 visceral materials from the dead animals with diarrhoea were cultured for Compylobacter jejuni. A total of 458 strains of campylobacters (445 strains of C. jejuni, 13 strains of C. coli) were isolated and identified, and some biological characteristics of these strains were observed. Lior's biotyping scheme was used for biotyping 354 strains of campylobacters(253 strains of C. jejuni and 2 strains of C. coli). The results showed the most biological characteristics of these campylobacters accorded with that previously described in the literatures, but it were also found that there were some differences on morphological, cultural, physiological and biochemical characteristics and antibiotic resistances. In these differences, the most main differences were that 48.3% (215/445) of C. jejuni and 23.1% (3/13) of C. coli were resistant to nalidixic acid, and that 1.1% (5/445) of C. jejuni and 7.6(1/13) of C. coli were resistant to cefotaxime. There were relationships between antibiotic resistances and strain sources (P < 0.005). The result of biotyping 352 strains of C. jejuni indicated that biotype I (40.9%) and II (58.2%) were predominant in the bodies of these animals, and there were two biotypes distributed in the body of same animal.

[Study on the photoacoustic phase of rare earth complexes]

The theory of the photoacoustic (PA) phase has been studied. The PA phase spectra of rare earth complexes with dibenzoylmethide have been explained basing on the theory. The phase shifts of Tb complexes at the ligand absorption peak have been calculated. The phase shifts and their intramolecular relaxation processes have been studied also.

[Adherence of bovine lens epithelial cells to the surface of intraocular lens made of different materials]

OBJECTIVE

To compare the in vitro adherence of bovine lens epithelial cells (BLEC) onto the surface of intraocular lens (IOL) made of 4 different materials: polymethylmethacrylate (PMMA), silicone (SI), hydroxyethylmethacrylate (HEMA) and acrylic (Acrysof, ACRY).

METHODS

BLEC were incubated with IOLs four 48 hours. Adherent cells were counted by flow cytometry technique.

RESULTS

The amount of the adherent cells on IOLs of ACRY was the highest, that of HEMA the least, and there was no significant difference between the amount on PMMA and SI IOLs (P > 0.05).

CONCLUSIONS

Adherence of lens epithelial cells to IOLs is influenced by the surface property of IOL materials, which may influence the occurrence of postoperative capsular opacification after IOL implantation.

Loss of fhit expression in invasive cervical carcinomas and intraepithelial lesions associated with invasive disease

Allelic losses involving chromosome 3p are frequently observed in cervical cancers. Deletion mapping studies of primary cervical carcinomas have localized common regions of deletion to 3p14.2 and 3p21. The candidate tumor suppressor gene FHIT has been mapped to 3p14.2, and previous studies have demonstrated reduced or aberrant FHIT transcripts and reduced or absent Fhit protein expression in a large percentage of cervical cancer-derived cell lines and primary cervical carcinomas. To expand these observations to preinvasive cervical epithelial lesions and to determine whether loss of Fhit protein expression might be associated with tumor progression, immunohistochemical methods were used to examine Fhit expression in 95 invasive cervical carcinomas, 33 high-grade squamous intraepithelial lesions (HSILs) associated with concurrent invasive cancer, 38 HSILs unassociated with invasive cancer, 24 low-grade squamous intraepithelial lesions, and 22 normal cervix samples. All normal cervical epithelia and low-grade squamous intraepithelial lesions exhibited diffuse cytoplasmic immunostaining of moderate to strong intensity. Fhit protein expression was markedly reduced or absent in 67 of 95 (71%) invasive cancers, 17 of 33 (52%) HSILs associated with invasive cancer, and 8 of 38 (21%) HSILs without associated invasive cancer. The results confirm that Fhit protein expression is reduced or absent in the majority of cervical carcinomas and suggest that loss of Fhit expression often accompanies cervical tumor progression. Moreover, absent or reduced Fhit protein is observed at a significantly higher frequency in HSILs associated with progression to invasive cancer than in HSILs with unknown risk for progression (P = 0.012). These findings suggest that loss of Fhit expression in HSILs could serve as a useful marker of high-grade preinvasive lesions that have an increased likelihood of progression to invasive carcinoma.

[Combined phacoemulsification, foldable intraocular lens implantation and trabeculectomy for cataract patients with glaucoma]

OBJECTIVE

To evaluate the therapeutic effects and safety of the combined phacoemulsification, foldable intraocular lens implantation and trabeculectomy (triple procedure) and compare the outcomes of the operation with two different small incisions, conventional scleral flap and scleral tunnel flap.

METHODS

Triple procedure was performed through a 3.5 mm incision by means of conventional scleral flap or scleral tunnel flap on 44 eyes of 42 patients with cataract and glaucoma.

RESULTS

After follow-up for 3 -- 6 months, the mean intraocular pressure (IOP) was (14.33 +/- 3.68) mm Hg (1 mm Hg = 0.133 kPa) with a mean pressure reduction of 10.35 mm Hg from that before the operation (P < 0.001). Postoperatively, the visual acuities were >or= 0.5 in 33 eyes (75.0%) at 1 week and in 37 eyes (84.1%) during 3 - 6 months. The mean postoperative astigmatism was (1.29 +/- 0.93) D at 1 week and only 0.17D more than the mean preoperative one (P > 0.05). There was also no statistical difference between the mean preoperative astigmatism and postoperative astigmatism at 3 - 6 months, which was (1.12 +/- 0.73) D. The filtering blebs of type I and II (functional) by Kronfeld's classification presented in 79.5% of the eyes and type III (non-functional) in 20.5% of the eyes. There were no statistical differences for the postoperative outcomes of IOP, visual acuity, astigmatism and filtering bleb between two different procedure groups (P > 0.05).

CONCLUSIONS

The triple procedure is an effective, quick, repeatable and safe procedure for cataract patients with glaucoma. There are no differences at the surgical outcomes of two different incisions by means of the conventional scleral flap vs scleral tunnel flap.

Circulating heat shock protein 60 is associated with early cardiovascular disease

The phylogenetically conserved nature of heat shock proteins (Hsp) has led to the proposition that they may provide a link between infection and the inflammatory component to vascular disease. Hypertension is associated with atherosclerosis. Here, we measured circulating heat shock protein and heat shock protein antibody levels in association with borderline hypertension. Seventy-two men with borderline hypertension patients and 75 normotensive control subjects (diastolic blood pressure 85 to 94 and <80 mm Hg, respectively) were selected from a population-screening program. The levels of Hsp60; Hsp70; and anti-human Hsp60, anti-human Hsp70, and anti-mycobacterial Hsp65 antibodies were determined with enzyme immunoassay. The presence of carotid atherosclerosis and the intima-media thickness values were determined with ultrasonography. A major novel observation in this report was the detection of circulating Hsp60, which was present at a significantly enhanced level in patients with borderline hypertension. Furthermore, serum Hsp60 was associated with intima-media thicknesses (P<0.01). Anti-Hsp65 antibody levels were higher in borderline hypertension (P<0.001), whereas Hsp70 and anti-Hsp70 antibody levels did not differ. In contrast to anti-Hsp65 antibody, anti-Hsp60 antibody levels were lower in borderline hypertension (P<0.03), although the difference was quantitatively small. None of the parameters evaluated were associated with atherosclerosis, metabolic factors, or smoking. We identified elevated Hsp60 levels in patients with borderline hypertension and an association between early atherosclerosis and Hsp60 levels. The physiological role of Hsp60 release has yet to be defined, but given the proinflammatory properties, these proteins could be involved in the induction/progression of both hypertension and atherosclerosis, as well as being markers for early cardiovascular disease.

Experimental study of the effect of external counterpulsation on blood circulation in the lower extremities

A bidirectional ultrasonic Doppler flowmeter with direct single sideband separation was used to measure blood flow in the femoral and dorsalis pedis arteries of 18 normal volunteers. Changes in blood-flow velocity and volume during external counterpulsation (ECP) with various sustaining times (the time for maintaining pressure) for inflation were studied. The results showed that blood-flow velocity in the femoral and dorsalis pedis arteries is increased significantly by ECP, but the change is not closely related to the duration of inflation. For a short sustaining time, the net forward blood-flow volume in arteries increased remarkably, but at longer sustaining times it dropped back significantly to a value even lower than that before ECP. The sustaining time for inflation to produce the maximum net forward flow volume (the optimal sustaining time of inflation) was found to be at one-quarter to one-third of the cardiac cycle. In a second study, changes in the calibre of the femoral artery and its collateral and anastomotic branches in the hind extremities in 5 dogs before and after ECP with an optimal sustaining time of inflation were examined by femoral arteriography. The experiments showed that the patency of collateral and anastomotic branches of the femoral artery was greater before than after ECP. The study suggests that ECP could be an effective treatment for improving the blood circulation in extremities.

[The degradation performance of bioabsorbable acylchitin fiber reinforced PLA composite materials in vitro and in vivo]

The present authors have investigated the degradation performance of acylchitin fiber reinforced polylactide composite materials plates both in vitro and in vivo. The initial flexural strength and the initial flexural modulus of this plate are 114.72 MPa and 3980.05 MPa, respectively. The flexural strength of this plate decreases to 31.42 MPa after the plate has been submerged in injectio natrii lactatic ringeri tissue fluid for a period of 16 weeks at 37 degrees C. Both the in vitro degradation performance and the strength retention of this plate are better than those of the self-reinforced PGA/PLA and PGA, though the initial strength of the latter two being much higher than that of the former. The degradation products of the chitin/PLA composite materials can be absorbed by metabolic pathway.

[Determination of trace Pb in heme chloride by ICP-AES]

In this paper, a method for the determination of trace Pb in heme chloride is studied. The matrix matching and background climinating methods are used to minimize interference. The spectral interferences of matrix elements to analytical line of detected element are also discussed. The rate of recovery is between 95%-107% and RSD is less than 2%. The detertion limit is 17 ng.mL-1. According the comparison to the methods of some samples decomposition, choose one best method. The samples have been got pleased result.

Safety and efficacy of digital rectal examination in patients with acute myocardial infarction

OBJECTIVE

Digital rectal examination (DRE) is often ignored or deferred in acute myocardial infarction (AMI). The aim of this study was to determine the safety and efficacy of DRE in patients with AMI.

METHODS

This was a prospective, comparative, stratified study in an inner-city teaching hospital. A total of 480 patients from intensive care and telemetry units were stratified into three groups. Group I included 160 patients with AMI in whom a DRE was performed and electrocardiographic (EKG) recordings were obtained. Group II included 155 patients with AMI in whom DRE was not done, but EKG recordings were made. Group III consisted of 165 patients without AMI in whom DRE was performed and EKG recordings were obtained. Sustained arrhythmias and vital signs were measured.

RESULTS

None of the patients developed sustained arrhythmias and there was no change in vital signs. DRE resulted in the detection of several clinically significant findings.

CONCLUSION

DRE was found to be safe in our stable patients with AMI.

Evaluation of L-DOPA biotransformation during repeated L-DOPA infusion into the striatum in freely-moving young and old rats

The aim of this study was to assess changes in L-3, 4-dihydroxyphenylalanine (L-DOPA) biotransformation in response to two-pulse infusion of L-DOPA into the striatum of freely-moving young (3-4 month) and old (21-26 month) male Wistar rats. In addition, the effects of L-DOPA infusion on the vesicular dopamine (DA) store in young rats were also studied. Both L-DOPA-induced DA overflow and uptake of the perfused L-DOPA by the striatum were used to study L-DOPA biotransformation during microdialysis. High potassium-induced DA depletion was performed to assess the dynamics of the vesicular DA store following L-DOPA infusion. Concentric microdialysis probes were stereotaxically implanted in the lateral striatum of rats of both age groups and microdialysis was begun 24 h later. All rats received 2x20 min infusions of 3 mgr L-DOPA separated by an interval of 60 min. In the striatum of both groups, L-DOPA-induced DA overflow and uptake of exogenous L-DOPA were both significantly enhanced during the second infusion compared to the first. In young rats, when a 20-min infusion of 3 mgr L-DOPA was given between 2x20 min infusions of 100 mM potassium, no increased DA release was seen at the second high potassium challenge compared with the first. Our results suggest that the enhancement of DA overflow induced by the second L-DOPA infusion is, at least partially, due to an increase in L-DOPA biotransformation, and not simply to an enlarged DA pool. In contrast to the in vitro results, our own in vivo results show that L-DOPA utilization in the aging striatum does not deteriorate with age.

Induction of cell cornification and enhanced squamous-cell marker SPRR1 gene expression by phorbol ester are regulated by different signaling pathways in human conducting airway epithelial cells

Phorbol ester is a strong inducer for both cell cornification and squamous-cell marker SPRR1 gene expression in conducting airway epithelial cells. However, the signaling pathways involved in the regulation of both events have not been completely elucidated. The current study focuses on the common and divergent pathways involved in the induction of these two activities by phorbol-13-myristate-12-acetate (PMA). Using a protein kinase (PK) C inhibitor, bisindolylmaleimide I, PMA-induced cell cornification and SPRR1 gene expression were abolished. Further, a PKC activator, indolactam V, induced cell cornification in the absence of PMA treatment. These results suggest a PKC-dependent signaling pathway for both gene induction and enhanced cell cornification by PMA. However, a mitogen-activated protein kinase-specific inhibitor, PD98059, could only block the gene induction event but failed to prevent cell cornification induced by PMA. These results suggest that diverse signaling pathways after PKC activation by PMA are involved in the regulation of these two events.

[Apoptosis of endothelial cells in alteration of microvascular permeability in lung during sepsis]

OBJECTIVE

To investigate the apoptosis of endothelial cells in the alteration of microvascular permeability in lung during sepsis.

METHODS

Twenty-four male NIH mice were subjected to cecal ligation and puncture (CLP) or sham operation (SO). The microvascular endothelial cells of the lungs were harvested at 3 hours and 12 hours after operation. The apoptosis of endothelial cells (VIII factor related antigen positive cells) in the lungs was determined by 2-color flow cytometry (FITC-labeled VIII factor related antigen and PI) and Apop Tag) in situ apoptosis detection kit in situ. The apoptosis related gene (bcl-2) was detected by RT-PCR. The microvascular permeability in lung tissue was also examined.

RESULTS

The apoptosis of microvascular endothelial cells was increased significantly at 12 hours after CLP (5.03 +/- 0.92 vs. 3.48 +/- 1.21, P < 0.05). The increased apoptosis was paralleled with the decrease in bcl-2 gene expression. The microvascular permeability in lung tissue was slightly increased at 3 hours after CLP, but significantly increased at 12 hours after CLP (0.106 +/- 0.008 vs 0.047 +/- 0.003, P < 0.01).

CONCLUSIONS

Apoptosis in microvascular endothelial cells seems to be an important reason for the alteration of microvascular permeability.

Evidence for the differential regulation of Nkx-6.1 expression in the ventral spinal cord and foregut by Shh-dependent and -independent mechanisms

The Nkx-6.1 homeodomain transcription factor was previously shown to be expressed in ventral neural progenitor cells and subsequently subsets of unidentified motor neurons during early neural development. In this study, we identify a specific subpopulation of motor neurons, the median half of the lateral motor neuron column (LMCm), that retain a strong expression of Nkx-6.1. In addition, we report novel patterns of Nkx-6.1 expression in several mesenchymal tissues surrounding Sonic hedgehog (Shh)-expressing cells, including ventral spinal meninges, esophageal mesenchyme, and dorsal tracheal mesenchyme. Whereas Shh signaling is required for Nkx-6.1 expression in the ventral neural tube and spinal meninges, an Shh-independent pathway appears to operate in regulating Nkx-6.1 expression in the foregut. The persistent and robust expression of Nkx-6.1 in motor neurons and mesenchymal cells suggests an important role for Nkx-6.1 in controlling cell fate specification and differentiation. genesis 27:6-11, 2000.

Nuage constituents arising from mitochondria: is it possible?

An ultrastructural study of nuage-mitochondria complexes in spermatogonia of the sea urchin, Anthocidaris crassispina, was carried out. Release of mitochondrial contents into the cytoplasm was observed. The mitochondrial derivatives persisted as cristae-containing globules of friable material that subsequently contacted and integrated with nuage. The present ultrastructural findings agree with the results of other researchers who proposed that germ plasm substance probably produced by the nucleus is supplemented by the mitochondrial genome.

A novel mechanism of retinoic acid-enhanced interleukin-8 gene expression in airway epithelium

A 3- to 8-fold stimulation of interleukin (IL)-8 gene expression by all-trans-retinoic acid (ATRA) was demonstrated in primary cultures of human and monkey tracheobronchial epithelial cells and BEAS-2B serum-sensitive cell line. The effect of ATRA on IL-8 gene expression is dose- and time-dependent. Using cycloheximide, it was observed that new protein synthesis was required for the stimulation. ATRA had no effect on IL-8 messenger RNA stability. A difference in nuclear run-on activity suggests that a transcriptional mechanism is involved in ATRA-enhanced IL-8 gene expression. Promoter-reporter gene transfection studies demonstrated ATRA enhanced IL-8 promoter activity, especially when cells were cotransfected with retinoic acid nuclear receptor-alpha expression vector. Deletion and site-directed mutagenesis analysis revealed the involvement of nuclear factor (NF)-kappaB binding site of the IL-8 gene in ATRA-enhanced promoter activity. Electrophoretic mobility shift assay (EMSA) demonstrated that ATRA enhanced DNA-NF-kappaB complex formation, especially with the p65 subunit. Western blot analysis demonstrated that ATRA did not enhance the protein amount of both the p50 and the p65 subunits in the nuclei. Because ATRA also enhances thioredoxin (TRX) gene expression, the effect of TRX on IL-8 gene expression was examined. IL-8 promoter activity was enhanced in transfected cells by the addition of TRX protein. Treatment of nuclear extracts with TRX also enhanced DNA- NF-kappaB complex formation as observed by EMSA, particularly the p65 subunit. Taking these data together, a novel mechanism is proposed in which ATRA activates promoter activity of IL-8 gene through TRX-dependent NF-kappaB activation.

Recognition and binding of the human selenocysteine insertion sequence by nucleolin

Prokaryotic and eukaryotic cells cotranslationally incorporate the unusual amino acid selenocysteine at a UGA codon, which conventionally serves as a termination signal. Translation of selenoprotein gene transcripts in eukaryotes depends upon a "selenocysteine insertion sequence" in the 3'-untranslated region. We have previously shown that DNA-binding protein B specifically binds this sequence element. We now report the identification of nucleolin as a partner in the selenoprotein translation complex. In RNA electromobility shift assays, nucleolin binds the selenocysteine insertion sequence from the human cellular glutathione peroxidase gene, competes with binding activity from COS cells, and shows diminished affinity for probes with mutations in functionally important, conserved sequence elements. Antibody to nucleolin interferes with the gel shift activity of COS cell extract. Antibody to DNA-binding protein B co-extracts nucleolin from HeLa cell cytosol, and the two proteins co-sediment in glycerol gradient fractions of ribosomal high salt extracts. Thus, nucleolin appears to join DNA-binding protein B and possibly other partners to form a large complex that links the selenocysteine insertion sequence in the 3'-untranslated region to other elements in the coding region and ribosome to translate the UGA "stop" codon as selenocysteine.

Oxidative stress disrupts glucocorticoid hormone-dependent transcription of the amiloride-sensitive epithelial sodium channel alpha-subunit in lung epithelial cells through ERK-dependent and thioredoxin-sensitive pathways

The amiloride-sensitive epithelial Na(+) channel (ENaC) plays a critical role in the maintenance of alveolar fluid balance. It is generally accepted that reactive oxygen and nitrogen species can inhibit ENaC activity and aggravate acute lung injury; however, the molecular mechanism for free radical-mediated ENaC inhibition is unclear. Previously, we showed that the expression of the alpha-subunit of ENaC, alpha-ENaC, which is indispensable for ENaC activity, is repressed by Ras activation in salivary epithelial cells. Here, we investigated whether exogenous H(2)O(2) modulates alpha-ENaC gene expression in lung epithelial cells through a similar molecular mechanism. Utilizing transient transfection reporter assays and site-directed mutagenesis analyses, we found that the glucocorticoid response element (GRE), located at -1334 to -1306 base pairs of the alpha-ENaC 5'-flanking region, is the major enhancer for the stimulated alpha-ENaC expression in A549 lung epithelial cells. We further demonstrate that the presence of an intact GRE is necessary and sufficient for oxidants to repress alpha-ENaC expression. Consistent with our hypothesis, exogenous H(2)O(2)-mediated repression of alpha-ENaC GRE activity is partially blocked by either a specific inhibitor for extracellular signal-regulated kinase (ERK) pathway activation, U0126, or dominant negative ERK, suggesting that, in part, activated ERK may mediate the repressive effects of H(2)O(2) on alpha-ENaC expression. In addition, overexpression of thioredoxin restored glucocorticoid receptor action on the alpha-ENaC GRE in the presence of exogenous H(2)O(2). Taken together, we hypothesize that oxidative stress impairs Na(+) transport activity by inhibiting dexamethasone-dependent alpha-ENaC GRE activation via both ERK-dependent and thioredoxin-sensitive pathways. These results suggest a putative mechanism whereby cellular redox potentials modulate the glucocorticoid receptor/dexamethasone effect on alpha-ENaC expression in lung and other tight epithelia.

Multiwatt High-Repetition-Rate 2-microm Output from an Intracavity KTiOPO(4) Optical Parametric Oscillator

We have obtained 6.5 W of 2-mum output from a near-degenerate, type II KTiOPO(4) (KTP) optical parametric oscillator (OPO) pumped within the cavity of a Q-switched diode-pumped Nd:YAG laser that operates at 3 kHz. We adopted the simplest configuration with a compact diode-pumped Nd:YAG module pumping the doubly resonant KTP OPO in its randomly polarized resonator with an acousto-optic Q switch. Attempts to increase the 2-mum output power by pumping this intracavity KTP OPO with a polarized laser beam by use of thermal birefringence compensation configurations are discussed.