The coherent electron microdiffraction of a single translation domain boundary in β-Ni3Nb phase

The microdiffraction from a single translation domain boundary (TDB) in β-Ni3Nb has been recorded by using a Hitachi HF-2000 field emission gun transmission electron microscope, while high-resolution transmission electron microscopy images were used to assist the analysis. The diffraction splitting effect of a TDB is well explained by the kinematics and dynamic calculations, and complex diffraction characteristics have been studied by using dynamics simulation.

Mitogenic up-regulation of the PRL-1 protein-tyrosine phosphatase gene by Egr-1. Egr-1 activation is an early event in liver regeneration

The cellular signals that initiate cell growth are incompletely understood. Insight could be provided by understanding the signals regulating the transcriptional induction of immediate-early genes which occurs within minutes of the growth stimulus. The expression of the PRL-1 gene, which encodes a unique nuclear protein-tyrosine phosphatase, is rapidly induced in regenerating liver and mitogen-treated cells. Transcription of the PRL-1 gene increased in the rat liver remnant within a few minutes after partial hepatectomy and largely explained the increase in steady-state PRL-1 mRNA in the first few hours posthepatectomy. Egr-1 (early growth response factor) specifically bound a region of the proximal PRL-1 promoter P1 (-99). Egr-1 binding activity was more rapidly induced in regenerating liver than mitogen-treated H35 and NIH 3T3 cells, remained elevated through 4 h posthepatectomy, and appeared to be dependent not only on new Egr-1 protein synthesis but on post-translational regulation of Egr-1. Egr-1 efficiently transactivated a PRL-1 promoter reporter construct containing an intact not mutant Egr-1 site, and the Egr-1 site largely accounted for PRL-1 gene up-regulation in response to mitogen stimulation. These data predict that Egr-1 activation is an early event in liver regeneration and mitogen-activated cells that provides a regulatory stimulus for a subset of immediate-early genes.

Transcriptional up-regulation of the delayed early gene HRS/SRp40 during liver regeneration. Interactions among YY1, GA-binding proteins, and mitogenic signals

Arg-Ser-rich domain-containing proteins (SR proteins), a family of splicing factors, can regulate pre-mRNA alternative splicing in a concentration dependent manner. Thus, the relative expression of various SR proteins may play an important role in alternative splicing regulation. HRS/SRp40, an SR protein and delayed early gene in liver regeneration, can mediate alternative splicing of fibronectin mRNA. Here we determined that transcription of the HRS/SRp40 gene is induced about 5-fold during liver regeneration, similar to the level of steady-state mRNA. We found that both mouse and human HRS promoters lack TATA and CAAT boxes. The mouse promoter region from -130 to -18, which contains highly conserved GA-binding protein (GABP) and YY1 binding sites, conferred high transcriptional activity. While GABPalpha/GABPbeta heterodimer transactivated the HRS promoter, YY1 functioned as a repressor. During liver regeneration, the relative amount of GABPalpha/GABPbeta heterodimer increased 3-fold, and YY1 changed little, which could partially account for the increase in HRS gene transcription. Interleukin-6, a critical mitogenic component of liver regeneration, was able to relieve the repressive activity of the YY1 site within the HRS promoter. The combined effect of small changes in the level of existing transcription factors and mitogenic signals may explain the transcriptional activation of the HRS gene during cell growth.

CREB is a regulatory target for the protein kinase Akt/PKB

The nuclear factor CREB stimulates the expression of cellular genes following its protein kinase A-mediated phosphorylation at Ser-133. Ser-133 phosphorylation, in turn, activates target gene expression by promoting recruitment of the co-activator CBP. Recent studies showing that CREB and its paralog CREM are required for survival of certain cell types prompted us to examine whether CREB is a nuclear target for activation via the growth factor-dependent Ser/Thr kinase Akt/PKB. When overexpressed in serum-stimulated cells, Akt/PKB potently induced Ser-133 phosphorylation of CREB and promoted recruitment of CBP. Correspondingly, Akt/PKB stimulated target gene expression via CREB in a phospho(Ser-133)-dependent manner. Akt/PKB induced CREB activity only in response to serum stimulation, and this effect was suppressed by the phosphatidylinositol 3-kinase inhibitor LY 294002. Our results support the notion that Akt/PKB promotes cell survival, at least in part, by stimulating the expression of cellular genes via the CREB/CBP nuclear transduction pathway.

The Gfi-1B proto-oncoprotein represses p21WAF1 and inhibits myeloid cell differentiation

Gfi-1 is a cellular proto-oncogene that was identified as a target of provirus integration in T-cell lymphoma lines selected for interleukin-2 (IL-2) independence in culture and in primary retrovirus-induced lymphomas. Gfi-1 encodes a zinc finger protein that functions as a transcriptional repressor. Here we show that Gfi-1B, a Gfi-1 related gene expressed in bone marrow and spleen, also encodes a transcriptional repressor. IL-6-induced G1 arrest and differentiation of the myelomonocytic cell line M1 were linked to the downregulation of Gfi-1B and the parallel induction of the cyclin-dependent kinase inhibitor p21WAF1. Experiments addressing the potential mechanism of the apparent coordinate regulation of these genes revealed that Gfi-1B represses p21WAF1 directly by binding to a high-affinity site at -1518 to -1530 in the p21WAF1 promoter. Forced expression of Gfi-1B, but not of Gfi-1B deletion mutants lacking the repressor domain, blocked the IL-6-mediated induction of p21WAF1 and inhibited G1 arrest and differentiation. We conclude that Gfi-1B is a direct repressor of the p21WAF1 promoter, the first such repressor identified to date, and that sustained expression of Gfi-1B blocks IL-6-induced G1 arrest and differentiation of M1 cells perhaps because it prevents p21WAF1 induction by IL-6.

Neodymium:YAG 30-W cw Laser Side Pumped by Three Diode Laser Bars

A theoretical calculation of pump power deposition in a direct water-cooled Nd:YAG laser rod, side pumped by three diode laser bars is presented. The pumping cavity design provides a nearly uniform pump profile. More than 30-W cw output power with optical-to-optical efficiencies of more than 30% are obtained.

Partially end-pumped Nd:YAG slab laser with a hybrid resonator

A Nd:YAG slab is partially end pumped by a diode laser stack with three diode laser bars. The pumped volume has a rectangular cross section. A hybrid resonator, which is stable in the plane of small dimension and is off-axis unstable in the plane of large dimension of the gain cross section, was used to yield highly efficient laser operation at diffraction-limited beam quality. The laser design and experimental results are reported.

Site-directed mutagenesis of human vasoactive intestinal peptide receptor subtypes VIP1 and VIP2: evidence for difference in the structure-function relationship

Vasoactive intestinal peptide (VIP1 and VIP2) receptors belong to the new class II subfamily of G protein-coupled receptors. We investigated here human VIP1 and VIP2 receptors by mutating in their extracellular domains all amino acid residues that are conserved in VIP receptors but are different in other members of their subfamily. They are present in 1) the N-terminal domain, i.e., E36, I43, S64, D132 and F138 in the VIP1 receptor and E24, I31, S53, D116 and F122 in the VIP2 receptor; 2) the second extracellular loop, i.e., T288 and S292 in the VIP1 receptor and T274 and S278 in the VIP2 receptor. These residues were changed to alanine (A), and cDNAs were transfected into Cos cells. For the VIP1 receptor, no specific 125I-VIP binding could be detected in cells transfected with the E36A mutant, whereas other mutants exhibited Kd values similar to that of the wild-type receptor, with the exception of S64A, for which a 3-fold increase of Kd was observed. For the VIP2 receptor, no specific 125I-VIP binding could be observed with the E24A mutant, whereas other mutants exhibited dissociation constants similar to that of the wild-type receptor, with the exception of I31A and T274A mutants, for which a 11- and 5-fold increase of Kd was observed, respectively. cAMP production experiments provided evidence that the E36A VIP1 receptor and the E24A VIP2 receptor mutants mediated almost no response upon VIP exposure. For the I31A and T274A mutants of the VIP2 receptor and the S64A mutant of the VIP1 receptor, the EC50 values of VIP for stimulating cAMP production were increased 35, 8 and 3 times as compared with that observed for the wild-type receptor, respectively. Immunofluorescence studies indicated that all mutants were normally expressed by Cos cells. These data provide the first evidence for differences in the structure-function relationship of VIP1 and VIP2 receptors.

Alternative splicing and structure of the human and mouse SFRS5/HRS/SRp40 genes

HRS/SRp40/SFRS5 (HRS) is an SR (serine-arginine-rich) protein which regulates both alternative splicing and basal splicing. HRS mRNA contains several transcripts, including HRS-SF and HRS-LF which have different temporal patterns of expression in proliferating liver. As previously reported, HRS-SF mRNA encodes the SR splicing factor. However, the identity of HRS-LF remained unknown. Here, we cloned and characterized the mouse HRS gene, partial human HRS gene, and several cDNAs derived from HRS-LF mRNA. The mouse HRS gene spans 5050 bp and contains eight exons and seven introns. HRS-LF mRNA contains a 1.2 kb insert within the SF mRNA with stop codons in all three reading frames. A comparison of HRS-LF and the HRS gene revealed that HRS-LF mRNA is an intron-retaining product which contains intron 5. At most, HRS-LF encodes a truncated HRS protein with one RNA binding domain. Interestingly, intron 5 demonstrates 90% identity between the mouse and human HRS genes, implying that intron 5 might play an important role in regulating HRS gene splicing or expression.

Polarization characteristics of a Nd:YAG laser side pumped by diode laser bars

A detailed experimental investigation of the polarization characteristics of a diode laser side-pumped Nd:YAG laser has been performed. A Brewster plate inserted into the cavity resulted in a decrease of 50% of the output power that is due to depolarization. A thin-film polarizer (TFP) was introduced into the cavity and the depolarization loss served as the output coupling. By introduction of a quarter-wave plate (QWP) the output coupling rate and the beam shape were improved. An analytical expression for the output coupling rate of a cavity containing a TFP and a QWP has been derived. The experimental results are in good agreement with the simplified theoretical analysis.

Highly efficient diode-stack, end-pumped Nd:YAG slab laser with symmetrized beam quality

An efficient high-power cw Nd:YAG slab laser, partially end pumped by diode-laser stacks, and a novel beam-shaping technique are reported. The optical efficiency amounted to 44 %, and the slope efficiency amounted to 55 %. Introducing an intracavity Brewster plate to polarize the laser beam, we obtained an optical efficiency of 35 % and a slope efficiency of 41 %. The output beam was rectangular and the beam quality asymmetric in two orthogonal directions. To equalize the beam quality, we introduced a step-mirror beam-shaping technique. The beam-shaping technique and the results obtained are discussed.

Expression analysis and chromosomal assignment of the human SFRS5/SRp40 gene

Alternative splicing plays a major role in the regulation of gene expression. SFRS5/SRp40 is a member of the serine/arginine (SR) protein family of regulators of alternative pre-mRNA splicing. We cloned the human SFRS5 cDNA and observed two major SFRS5 transcripts, an approximately 1.8-kb short form and an approximately 3.3-kb long form, in both human and rat tissues. Both transcripts were detected in all human tissues examined, but there were notable tissue-specific differences in their relative abundance, the short form being most abundant in retina. Affinity-purified SFRS5 antisera recognized a single 40-kDa polypeptide in human and mouse retinal lysates. The abundant retinal expression of SFRS5 was not restricted to any specific cell type, since immunofluorescent labeling of human retinal sections identified the SFRS5 protein in nuclei of all three nuclear layers of the retina. The human SFRS5 gene was localized to human chromosome 14q24 by fluorescence in situ hybridization and PCR analysis of a human/hamster somatic cell hybrid panel.

HRS/SRp40-mediated inclusion of the fibronectin EIIIB exon, a possible cause of increased EIIIB expression in proliferating liver

Serine-arginine (SR)-rich proteins are believed to be important in mediating alternative pre-mRNA splicing. HRS/SRp40 expression is elevated in liver cell proliferation during development, regeneration, and oncogenesis. We tested whether HRS expression correlates with the appearance of alternatively spliced fibronectin transcripts during liver growth. HRS was highly expressed during the proliferative phase of liver development, correlating with expression of the fibronectin EIIIB alternative exon. In regenerating liver, HRS protein was induced in a time course consistent with the observed increase in fibronectin transcripts containing the EIIIB exon, particularly in nonparenchymal liver cells. Furthermore, in an in vivo assay, HRS, and not other SR proteins, directly mediated EIIIB exon inclusion in the fibronectin transcript. This alternative splicing was dependent on a purine-rich region within the EIIIB exon to which HRS specifically bound. We have established that HRS has the potential to contribute to the regulation of fibronectin pre-mRNA splicing during liver growth. Changes in fibronectin forms may be important in modifying liver architecture during the proliferative response, thus providing a potential mechanism by which SR proteins may participate in cellular growth control.

Improved methods for making and using glass knives

We have observed over time that the right side of a glass knife is the optimal cutting edge for microtomy if the counterpiece (heel opposite the edge) is controlled within 1 mm. The right cutting edge has been considered the "saw toothed" side and has not been used for ultrathin sectioning. We have observed that the right cutting edge is sharper and more durable than the left. Light and scanning electron microscopy were used to observe the cutting edge, and transmission electron microscopy was used to examine semithin and ultrathin sections of animal and plant tissues cut by the right and left sides of the cutting edge. The results indicate that the cutting edge becomes sharper and more durable from left to right. Both the quality and efficiency of ultrathin sectioning is improved by using the right cutting edge.

[The design of an OEM module-based hand-hold pulse oximeter]

This paper describes the software and hardware design of an OEM module-based hand-hold pulse oximeter. The instrument has the features of compact structure, reliable performance, having all the necessary functions, providing measurements on any patients and low power consumption. It is possible to make this instrument as a commercial product in shorter period.

Aspartate 196 in the first extracellular loop of the human VIP1 receptor is essential for VIP binding and VIP-stimulated cAMP production

VIP receptors belong to a subfamily of G protein-coupled receptors that includes secretin, glucagon, PTH and several other receptors. We have used site-directed mutagenesis to investigate the requirement of some highly conserved residues in the extracellular loops including aspartate 196 (mutant D196A), leucine 199 (mutant L199A), tryptophane 286 (mutant W286A) and tryptophane 294 (mutant W294A) for the ability of the human VIP1 receptor to bind VIP and to mediate VIP-stimulated cAMP production. After transfection of mutated cDNAs in Cos-7 cells, it appeared that 1) mutants L199A, W286A and W294A bound VIP with the same dissociation constant as the wild-type receptor whereas mutant D196A did not bind 125I-VIP; 2) mutants L199A, W286A and W294A mediate VIP-stimulated cAMP production with the same EC50 as the wild-type receptor whereas VIP displayed a 500-fold decrease of potency in promoting cAMP production through mutant D196A. Since all mutated receptor proteins were expressed and delivered at the plasma membrane (immunofluorescence studies), it is concluded that the first extracellular loop of the human VIP1 receptor contains a highly conserved aspartate residue which is essential for VIP binding and VIP-stimulated cAMP production.

[Directed mutagenesis of human recombinant receptors of vasoactive intestinal peptide of VIP1 and VIP2 type. Difference in structure-activity relationship]

OBJECTIVES

Two vasoactive intestinal peptide (VIP) receptor subtypes have been cloned. We studied the structure-function relationship of human VIP1 and VIP2 receptors by mutating residues specifically conserved in extracellular domains of these receptors: N-terminal domain (E36, I43, S64, D132 and F138 in VIP1 receptor corresponding to E24, I31, S53, D116 and F122 in VIP2 receptor) and second loop (T288 and S292 in VIP1 receptor corresponding to T274 and S278 in VIP2 receptor).

METHODS

Residues were mutated into alanine (A) and the corresponding cDNAs were transfected into Cos cells. Wild-type and mutated receptors were characterized in transfected cells by ligand binding assay using 125I-VIP and cAMP measurements upon VIP challenge.

RESULTS

Regarding the VIP1 receptor, no specific binding of 125I-VIP could be detected on Cos cells transfected with the E36A mutant whereas other mutants, with the exception of S64A, exhibited dissociation constants similar to that of the wild-type receptor. The S64A mutant showed a 3-fold increase of its dissociation constant as compared to the wild-type receptor. cAMP experiments showed that the E36A mutant mediated a very weak stimulation by VIP. Regarding the VIP2 receptor, no specific binding of 125I-VIP could be detected on Cos cells transfected with the E24A. I31A and T274A mutants whereas all other mutants exhibited dissociation constants similar to that of the wild-type receptor. cAMP experiments showed that the E24A mutant mediated a very weak stimulation by VIP. Regarding I31A and T274A mutants, the EC50 values were increased 10 and 50 times as compared to the wild-type receptor, respectively.

CONCLUSION

a) The conserved glutamate (E) residue in the N-terminal domain of VIP1 and VIP2 receptors is crucial for VIP binding; b) The VIP2 receptor contains two conserved residues isoleucine 31 and threonine 274 which are critical for VIP binding while they can be mutated without loss of function in the VIP1 receptor. This difference in the structure-function relationship should be instrumental for the development of a selective pharmacology of VIP receptor subtypes.

[The cloning and expression of human secreted interleukin 2 receptor alpha chain gene in eukaryotic cells]

By deleting the sequences encoding the cytoplasmic domain, transmembrane domain and the 5' untranslated region, human interleukin-2 receptor alpha cDNA fragment was subcloned into an eukaryotic expression vector pRc/CMV. The recombinant plasmid was then transfected into CHO cells by either electroporation or calcium phosphate precipitation. 11 G418-resistent clones were randomly selected for detection of mRNA expression. 5 clones out of the 11 were proved to be positively hybridyzed with IL-2R alpha cDNA probe. All of the 5 positive cell lines also expressed sIL-2R alpha in their supernatants as detected by ELISA. The establishment of rhsIL-2R alpha cell lines is of importance in the detection and purification of IL-2 based on the ability of affinity binding between IL-2 and its recombinant receptor.

Novel delayed-early and highly insulin-induced growth response genes. Identification of HRS, a potential regulator of alternative pre-mRNA splicing

We have identified 41 novel and many previously known growth response genes induced in regenerating liver and insulin-treated Reuber H35 cells, a rat hepatoma cell line that grows in response to physiologic concentrations of insulin and retains some properties of regenerating liver. Although many genes are expressed similarly in the two systems, there are important differences in the kinetics of induction of some genes. These differences allowed us to identify and characterize novel genes that are highly insulin-induced and expressed as delayed-early genes in regenerating liver. Sequence analysis of CL-6, the most abundant insulin-induced gene, resulted in the identification of a highly hydrophobic hepatic protein. Sequence analysis of HRS, a highly insulin-induced delayed-early gene, demonstrated that it is a member of the family of regulators of alternative pre-mRNA splicing. Different forms of HRS mRNA are temporally regulated during the growth response, suggesting that HRS could autoregulate processing of its pre-mRNA. Given the dramatic increase in RNA production during late G1, proteins induced by mitogens like insulin that control RNA processing are likely to have important roles in cell cycle regulation.