[Computerized transformation of the cardiotocographic paper record to its digital equivalent for computerised analysis]

OBJECTIVE

To analyze cardiotocograph by computer, the tracings recorded in paper form must first be converted into their digital equivalent. We developed a method by which this process may be performed.

METHODS

Paper recordings were first scanned using a conventional flat bed scanner to obtain a digital image. Each image was firstly corrected for rotational misalignment error during scanning and, sceondly the grid was removed by performing logistic contrast enhancement to leave the discrete fetal heart rate and tocographic tracings. The method was validated by comparing differences between the fetal heart rate obtained from the paper record with that directly obtained from the fetal monitor.

RESULTS

Forty recordings were analyzed. The mean difference per recording between the actual and derived values ranged from -0.26(-)-1.26 beats per minute. The 95% confidence interval for the pooled differences between the derived and actual fetal heart rate values was--7-5 beats per minute.

CONCLUSION

By using the techniques described in this paper, it is now possible to convert the large number of paper records available so that they can be analyzed by computerized cardiotocograph interpreters.

Impaired gas mixing and low lung volume in preterm infants with mild chronic lung disease

The aim of this study was to assess the possible role of gas mixing inefficiency in spontaneously breathing infants with mild chronic lung disease (CLD) of prematurity in relation to changes in other functional parameters. A simple bedside technique for recording and analysis of multiple breath nitrogen washout curves was applied together with occlusion mechanics. Fifteen preterm infants with mild or moderately severe CLD were studied at a mean postconceptional age of 35 wk, together with 15 healthy preterm infants at the same maturity. All infants breathed spontaneously, and the test was performed by a continuous bypass flow system, connected to a face mask, a pneumotachograph, and a nitrogen meter. The results showed impaired gas mixing with moment ratios above the 95th percentile of the normal group in 11/15 infants with CLD. Functional residual capacity (FRC) was low in 13/15 infants, but specific compliance and resistance of the respiratory system did not differ between the groups. As FRC and moment ratios were not correlated, it is suggested that they may reflect different aspects of the pathophysiology in CLD. It is concluded that low FRC and disturbed gas mixing are characteristic disturbances in CLD at different degrees of severity. The multiple breath nitrogen washout test, followed by moment analysis of end-tidal nitrogen concentrations, is a simple and sensitive method for detection of these disturbances and for monitoring purposes.

Inhibition of Alzheimer beta-fibrillogenesis by melatonin

It is generally postulated that the amyloid beta protein (Abeta) plays a central role in the progressive neurodegeneration observed in Alzheimer's disease. Important pathologic properties of this protein, such as neurotoxicity and resistance to proteolytic degradation, depend on the ability of Abeta to form beta-sheet structures or amyloid fibrils. We report that melatonin, a hormone recently found to protect neurons against Abeta toxicity, interacts with Abeta1-40 and Abeta1-42 and inhibits the progressive formation of beta-sheets and amyloid fibrils. These interactions between melatonin and the amyloid peptides were demonstrated by circular dichroism and electron microscopy for Abeta1-40 and Abeta1-42 and by nuclear magnetic resonance spectroscopy for Abeta1-40. Inhibition of beta-sheets and fibrils could not be accomplished in control experiments when a free radical scavenger or a melatonin analog were substituted for melatonin under otherwise identical conditions. In sharp contrast with conventional anti-oxidants and available anti-amyloidogenic compounds, melatonin crosses the blood-brain barrier, is relatively devoid of toxicity, and constitutes a potential new therapeutic agent in Alzheimer's disease.

Gangliosides enhance apoptosis of thymocytes

Monosialogangliosides, normal components of cell membranes, regulate cell development and differentiation in several organs. Our previous observation of dramatic premature thymic involution in cats with feline GM1 gangliosidosis, whose thymocytes have abnormally high cell surface gangliosides, suggested that excess GM1 ganglioside (GM1) could modulate thymocyte apoptosis in this disease (Cox et al., "Thymic Alterations in Feline GM1 Gangliosidosis," submitted). In these studies, we added exogenous GM1 to murine primary thymocyte cultures and demonstrated enhanced apoptosis in treated cells by DNA fragmentation, apoptotic body, and electrophoretic analyses. GM1-enhanced apoptosis was blocked by common apoptotic pathway inhibitors including aurintricarboxylic acid (inhibitor of endonuclease activity), actinomycin D (inhibitor of RNA transcription), and cycloheximide (inhibitor of protein synthesis). GM1 treatment primarily affected the immature CD4+ CD8+ subset, as shown by flow cytometric evaluation of fetal thymic organ culture and primary thymocyte cultures. Apoptosis also could be induced by GM2, GM3, and GT1b, whereas asialo-GM1 failed to do so, suggesting that the sialic acid moiety may play an important role in the induction of thymocyte apoptosis.

Disease induction by virus derived from molecular clones of equine infectious anemia virus

Equine infectious anemia virus (EIAV), a macrophage-tropic lentivirus, causes persistent infections of horses. A number of biologic features, including the rapid development of acute disease, the episodic nature of chronic disease, the propensity for viral genetic variation, and the ability for many infected animals to eventually control virus replication, render EIAV a potentially useful model system for the testing of antiretroviral therapies and vaccine strategies. The utility of the EIAV system has been hampered by the lack of proviral clones that encode promptly pathogenic viral stocks. In this report, we describe the generation and characterization of two infectious molecular clones capable of causing acute clinical syndromes similar to those seen in natural infections. Virus derived from clone p19/wenv17 caused severe debilitating disease at 5 to 7 days postinfection; initial febrile episodes were fatal in two of three infected animals. Virus derived from a second clone, p19/wenv16, caused somewhat milder primary febrile episodes by 10 to 12 days postinfection in two of two infected animals. Virus derived from both clones caused persistent infections such that some animals exhibited chronic equine infectious anemia, characterized by multiple disease episodes. The two virulent clones differ in envelope and rev sequences.

Moment analysis of multibreath nitrogen washout in healthy preterm infants

Moment analysis (MA) of multibreath nitrogen washout (MBNW) has not previously been applied to newborn infants. The aim of the present study was to adapt this method to healthy preterm infants using an improved technique suitable for small infants, and to determine reference values of MA. Twenty healthy preterm infants with a mean birth weight (+/-SD) of 1,666+/-402 g and a mean gestational age of 31.3+/-2.1 weeks were studied during their first 7-28 days of life. Computerized bedside equipment with very low dead space was constructed. The limits of normal variability were determined from results of duplicate studies. Outcome variables included functional residual capacity (FRC), the first-to-zeroth moment ratio (M1/M0), the second-to-zeroth moment ratio (M2/M0), and the lung clearance index (LCI). The starting point for MA had considerable impact on the results. Mean M1/M0 and M2/M0 were 2.18+/-0.18 and 8.71+/-1.24, respectively. No significant relation between moment ratios and weight, gender or age was found. Intrasubject coefficients of variation (CV) for M1/M0 (7.9+/-5.9%) and for M2/M0 (12.1+/-9.1%) and intersubject CV for M1/M0 (8%) and M2/M0 (14%) were similar to those reported in children and adults. Mean lung clearance index was 10.8+/-1.4 and intra- and intersubject CVs were 11.3+/-8.9% and 13%, respectively. Mean functional residual capacity (FRC) was 22.5+/-2.1 ml/kg. Mean intra- and intersubject CVs for FRC were 8.3% and 9%, respectively. We conclude that the MBNW test can be performed by a simple bedside method and that MA appears to be a suitable method for measuring gas mixing in preterm infants.

A role for Ras signaling in coreceptor regulation during differentiation of a double-positive thymocyte cell line

Evidence suggests that the Ras/mitogen-activated protein kinase signaling pathway is required for positive selection of thymocytes. We have asked whether Ras activation is also sufficient to mediate changes in gene expression that are associated with positive selection. To accomplish this, we expressed a constitutively active form of Ras in the immature CD4+ 8+ DPK thymocyte cell line. DPK cells that express active Ras have reduced levels of CD8alpha and CD8beta at the level of cell surface protein and mRNA. These data provide evidence of a direct link between Ras signaling pathways and coreceptor regulation during positive selection. They also suggest that a sustained or potent Ras signal may play a critical role in directing thymocytes into the CD4 lineage. DPK cells that express active Ras, however, were not fully differentiated, indicating that Ras signaling provides only a partial signal for double-positive thymocyte differentiation.

A role for Ras signaling in coreceptor regulation during differentiation of a double-positive thymocyte cell line

Evidence suggests that the Ras/mitogen-activated protein kinase signaling pathway is required for positive selection of thymocytes. We have asked whether Ras activation is also sufficient to mediate changes in gene expression that are associated with positive selection. To accomplish this, we expressed a constitutively active form of Ras in the immature CD4+ 8+ DPK thymocyte cell line. DPK cells that express active Ras have reduced levels of CD8alpha and CD8beta at the level of cell surface protein and mRNA. These data provide evidence of a direct link between Ras signaling pathways and coreceptor regulation during positive selection. They also suggest that a sustained or potent Ras signal may play a critical role in directing thymocytes into the CD4 lineage. DPK cells that express active Ras, however, were not fully differentiated, indicating that Ras signaling provides only a partial signal for double-positive thymocyte differentiation.

[Research of a screening strategy for high prokaryotic expression clone]

The low expression in E. coli can be often explained by the beginning sequence that causes low translational initiation. A simple selection procedure is then used to enrich those sequences from the bank that lead to high levels of translation. The selection procedure is based on the use of a translationally coupled tetracycline resistance gene. The basic steps are as follows: (1) Construction of selection vector pBV223; (2) Screening high expression clones through different tetracycline concentrations. Several clones have been selected in 60 microg/ml concentration of tetracycline. So this system will provide an important way in preparation of some cytokines which have a low expression level in E. coli but have significant economic value.

Expression cloning of a novel farnesylated protein, RDJ2, encoding a DnaJ protein homologue

The CAAX farnesyltransferase is a heterodimeric enzyme that attaches a farnesyl group to a single cysteine in cellular proteins which terminate in the sequence CAAX, where C is cysteine, A is an aliphatic amino acid, and X is most often methionine or serine. Substrates include the p21ras proteins, nuclear lamins, and a series of retinal proteins. To date, a limited number of substrates for the farnesyltransferase have been identified, predominantly by demonstration of the attachment of a farnesyl group to previously identified cDNA clones which encode proteins containing an appropriate carboxyl-terminal tetrapeptide. We describe here the use of a cDNA fusion protein expression library, together with enzymatic in vitro [3H]farnesyl radiolabeling, as a means of identifying novel farnesylated proteins. One candidate cDNA was fully cloned and found to be a homologue of the Escherichia coli heat shock gene dnaJ. The predicted amino acid sequence of this protein was found to terminate with the tetrapeptide Cys-Ala-His-Gln, which conforms to the consensus sequence for recognition by farnesyltransferase, and was shown to undergo in vivo farnesylation. This farnesylated protein, designated RDJ2 (rat DnaJ homologue 2), is a novel and ubiquitously expressed DnaJ homologue and is the newest member of the subfamily of DnaJ-related proteins which are posttranslationally modified by protein farnesylation.

[Molecular characterization of genetic defects in hemophilia in Shanghai]

OBJECTIVE

To detect gene mutations in hemophilia A in Shanghai.

METHODS

PCR, denaturing gradient gel electrophoresis (DGGE) and DNA sequencing were used. Fifty Chinese cases of hemophilia A without intron 22 inversion, including 24 severe, 9 moderate and 17 mild cases, were screened. Genomic DNA was amplified using GC-clamped primers covering all the exons and flanking intron regions, excluding the middle portion of extron 14 encoding the B domain, but including the thrombin cleavage sites at AA740 and 1689. The amplified GC-clamped PCR fragments were then electrophoresed on DGGE. The abnormal bands were sequenced.

RESULTS

Eleven different mutations were identified, including 5 nonsense mutations, 5 missense mutations and one small deletion. Among them, 3 mutations, 466Lys (AAG)-Thr (ACG), 719Tyr (TAC)-Stop (TAG) and 312Ile (ATC)-xxC have not been reported before.

CONCLUSION

Apart from intron 22 inversion, most gene mutations in hemophilia A were point mutations resulted from single base substitution. Generally the genetic defects correspond to the clinical manifestations.

Kinetic characterization of the human retinoblastoma protein bipartite nuclear localization sequence (NLS) in vivo and in vitro. A comparison with the SV40 large T-antigen NLS

The retinoblastoma (RB) tumor suppressor is a nuclear phosphoprotein important for cell growth control and able to bind specifically to viral oncoproteins such as the SV40 large tumor antigen (T-ag). Human RB possesses a bipartite nuclear localization sequence (NLS) consisting of two clusters of basic amino acids within amino acids 860-877, also present in mouse and Xenopus homologs, which resembles that of nucleoplasmin. The T-ag NLS represents a different type of NLS, consisting of only one stretch of basic amino acids. To compare the nuclear import kinetics conferred by the bipartite NLS of RB to those conferred by the T-ag NLS, we used beta-galactosidase fusion proteins containing the NLSs of either RB or T-ag. The RB NLS was able to target beta-galactosidase to the nucleus both in vivo (in microinjected cells of the HTC rat hepatoma line) and in vitro (in mechanically perforated HTC cells). Mutational substitution of the proximal basic residues of the NLS abolished nuclear targeting activity, confirming its bipartite character. Nuclear accumulation of the RB fusion protein was half-maximal within about 8 min in vivo, maximal levels being between 3-4-fold those in the cytoplasm, which was less than 50% of the maximal levels attained by the T-ag fusion protein, while the initial rate of nuclear import of the RB protein was also less than half that of T-ag. Nuclear import conferred by both NLSs in vitro was dependent on cytosol and ATP and inhibited by the nonhydrolyzable GTP analog GTPgammaS. Using an ELISA-based binding assay, we determined that the RB bipartite NLS had severely reduced affinity, compared with the T-ag NLS, for the high affinity heterodimeric NLS-binding protein complex importin 58/97, this difference presumably representing the basis of the reduced maximal nuclear accumulation and import rate in vivo. The results support the hypothesis that the affinity of NLS recognition by NLS-binding proteins is critical in determining the kinetics of nuclear protein import.

[Study on the recognition and evolutionary genetics of the courtship song of species in Drosphila nasuta species subgroup]

The subgroup of Drosophila nasuta consists of 14 species, subspecies and taxa. It has a wide distribution in area of Indo-Pacific Ocean. The courtship song of species in nasuta subgroup is recorded for the first time in the paper. Some parameters of temporal pattern of pulse song were measured: the inter burst interval (IBI), the interpulse interval (IPI), the length of a pulse train (PTL), the number of pulses in a train (PN), the length of a pulse (PL) and the length of a cycle (CL). Computer analysis techniques were used to make spectral analysis of sine song. A three-dimensional power spectra of the sound was made. In this subgroup, the male of D. pulauna and Taxon-F didn't produce any sound signals during courtship, suggesting that the visual stimuli play an important role in mating process. By analysing the courtship sound signals of other species, subspecies and taxa, the sounds produced by courting male could be described as pulse song or as sine song. By studying the sounds of intra- or interspecific F1 hybrids we have found that the parameters of the temporal pattern of pulse song, for example, the mean value of IPI is controlled by X-linked and autosomal polygene and the sine song frequency is predisposed to the maternity. The phylogenetic tree of the subgroup is constructed based on the temporal pattern of the pulse sounds in different species, subspecies and taxa. The relationship within the members of the Drosophila nasuta subgroup is discussed.

Characterization and mutational studies of equine infectious anemia virus dUTPase

The macrophage tropic lentivirus, equine infectious anemia virus (EIAV), encodes a dUTPase in the pol gene that is required for efficient replication in macrophages. Two naturally occurring variants of the enzyme were expressed as recombinant proteins in Escherichia coli; metal chelate affinity chromatography was used to purify histidine-tagged recombinant enzymes to greater than 80% homogeneity in a single chromatographic step. Biochemical and enzymatic analyses of these preparations suggest that this method yields dUTPase that is suitable for detailed mutational analysis. Specific activities of preparations ranged from 4 x 10(3) to 5 x 10(4) units/mg. Recombinant EIAV dUTPase was highly specific for dUTP with a Km in the range of 3 to 8 microM. The enzyme was sensitive to inhibition by dUDP with little inhibition by other nucleotides or the reaction products, dUMP and PPi. The subunit organization of recombinant EIAV dUTPase was probed by gel filtration, glycerol gradient centrifugation, and chemical cross-linking, and is a trimer. We have begun mutational analyses by targeting a conserved domain present at the carboxyl terminus of all dUTPases that shares high homology to the phosphate binding loops (P-loops) of a number of ATP- and GTP-binding phosphatases. The P-loop-like motif of dUTPases is glycine rich but lacks the invariant lysine found in authentic P-loops. Deletion of this motif leads to loss of dUTPase activity; a series of point mutations that have been shown to inactivate authentic P-loops also abolish EIAV dUTPase activity.

Induction of the early growth response (Egr) family of transcription factors during thymic selection

There is little known about the regulation of gene expression during TCR-mediated differentiation of immature CD4+8+ (double positive) thymocytes into mature T cells. Using the DPK CD4+8+ thymocyte precursor cell line, we demonstrate that the early growth response-1 gene (Erg-1), encoding a zinc finger transcription factor, is rapidly upregulated after TCR stimulation. We also report that Egr-1 is expressed by a subset of normal double positive thymocytes in the thymic cortex, as well by a majority of medullary single positive thymocytes. Expression of Egr-1 is dramatically reduced in the thymus of major histocompatibility complex knockout mice, but can be induced by anti-CD3 antibody stimulation of isolated thymocytes from these animals. These and other data suggest that high level expression of Egr-1 in the thymus is a consequence of selection. A similar pattern of expression is found for family members Egr-2 and Egr-3. Using the DPK cell line, we also demonstrate that expression of Egr-1, 2, and 3 is dependent upon ras activation, as is the initiation of differentiation to a single positive cell. In contrast, the calcineurin inhibitor cyclosporin A, which inhibits DPK cell differentiation as well as positive selection, inhibits expression of Egr-2 and Egr-3, but not Egr-1. The identification of the Egr family in this context represents the first report of a link between the two known signaling pathways involved in positive selection and downstream transcriptional regulators.

Reciprocal expression of the Eph receptor Cek5 and its ligand(s) in the early retina

Recent evidence suggests that Eph receptor tyrosine kinases and their ligands provide positional information in the developing visual system. We previously found that the Eph receptor Cek5 is more highly expressed in the ventral than dorsal chicken embryonic retina. We now report the identification of a chicken ligand for Cek5 (cCek5-L) that is 75% identical to the ligand LERK2. In situ hybridization experiments do not reveal a dorsoventral gradient of cCek5-L transcripts in the optic tectum at Embryonic Day 8, suggesting that this ligand is not involved in guiding Cek5-expressing axons in the tectum. Surprisingly, it is in the retina that high levels of cCek5-L mRNA are present. In the early retina, cCek5-L is more highly expressed in the dorsal than the ventral aspect. Similarly, a Cek5 Ig chimera labels dorsal but not ventral retina, indicating that even if several Cek5 ligands are present, their overall distribution is complementary to that of Cek5. Hence, Cek5 and cCek5-L may both contribute to define anatomical compartments within the early retina. In contrast, in the 11-day embryonic retina the distributions of Cek5 and its ligand(s) show considerable overlap, suggesting changing functions as development progresses. In dissociated cultures of dorsal or ventral retinal cells seeded on plates coated with either receptor or ligand Ig chimeras, the interaction between Cek5 and its ligand(s) or cCek5-L and its receptor(s) is sufficient to mediate cell adhesion and allows neurite outgrowth.

Elevated levels of syndecan-1 expression confer potent serum-dependent growth in human 293T cells

Syndecan-1 is the best studied integral membrane proteoglycan and functions to modulate epithelial cell attachment and physiology. Extracellularly, syndecan-1 binds both growth factors and extracellular matrix components, and intracellularly, its cytoplasmic portion interacts with cytoskeletal components. To investigate the possible role of syndecan-1 in epithelial cell transformation that is characterized by alteration in extracellular matrix interactions and cytoskeleton architecture, we established stable transfectants of syndecan-1 in a highly transformed human renal epithelial line expressing two viral oncogenes, adenovirus E1a and SV40 large T antigen (293T cell line). Expression of syndecan-1 core protein and appropriate posttranslational attachment of glycosaminoglycan chains was confirmed by enzymatic digestion and Western blot analysis. Overexpresser cells grew at a significantly faster rate than the vector-transfected control cells in serum-rich media but showed a proliferative disadvantage in serum-reduced media. In addition to this serum dependency, syndecan-1 overexpression caused a partial reversal of the transformed phenotype with the expressing clones becoming more anchorage dependent and less motile than the vector-transfected counterparts. Surprisingly, the overexpressers were more tumorigenic when injected s.c. into nude mice. These results indicate that syndecan-1 expression plays a role in the control of cell proliferation and suggest that serum-dependent growth may be the more reflective of tumorigenicity in nude mice.

Synthesis, crystal structure and conformation in solution of four stereoisomeric cyclo-lanthionine derivatives

The synthesis of the four stereoisomeric cyclo-lanthionine derivatives: [formula: see text] (where AlaL denotes one end of the lanthionine unit) was carried out on a Kaiser-oxime resin starting from orthogonally protected lanthionine units. The peptide ring was prepared in 79-85% yield via amide bond formation by utilizing the method of peptide cyclization on an oxime resin (PCOR). The crystal and molecular structures of the protected cyclic dipeptides have been determined by X-ray diffraction techniques. The two cyclic lanthionine derivatives with chiralities of [R,S] and [S,R] crystallized in the orthorhombic space group P2(1)2(1)2(1) and the [R,R]- and [S,S]-cyclo-lanthionine derivatives in the monoclinic space group C2. The structures were solved by direct methods and refined to an R factor of 0.0368-0.0573. The ring amide bonds in all four compounds are cis, while the urethane group is trans and extended. The NMR spectra of the four stereoisomers in DMSO-d6 were used to determine their conformation in solution. The analysis of the NMR data with constrained distance geometry search showed the same conformational features in solution as in the crystalline state.

Regulation of signal transduction and DNA fragmentation in thymocytes by ethanol

We demonstrated previously that ethanol enhances apoptosis of murine thymocytes. In this report, we determined intracellular cAMP and cytosolic free calcium ([Ca2+]i) levels in mouse thymocytes following acute exposure to ethanol and investigated the involvement of cAMP, [Ca2+]i, protein kinase A (PKA), and protein kinase C (PKC) in thymocyte apoptotic death induced by ethanol. It was found that ethanol did not alter basal cAMP levels, but produced a dose-dependent, prolonged small [Ca2+]i increase within thymocytes. This dose dependence of [Ca2+]i increase was paralleled by the magnitude of DNA fragmentation induced by ethanol at various concentrations. Additionally, the ethanol-enhanced DNA fragmentation was blocked by H7, a PKC inhibitor, but not by potent PKA inhibitors having little or no effect on PKC. These data suggest that both [Ca2+]i increase and PKC activation triggered by ethanol may belong to the signal pathway(s) leading to thymocyte programmed death.

[Dynamic changes of the platelet granule membrane glycoprotein level in patients with acute myocardial infarction before and after thrombolysis]

Platelet granule membrane glycoprotein (GMP-140) level was measured by using 125I labelled monoclonal antibody in 37 patients with acute myocardial infarction before and after thrombolytic therapy. In a nonthrombolysis group, it was shown that platelet GMP-140 increased significantly at the moment of admission and reached peak value 48 hours after AMI attack, then it decreased gradually and returned to baseline on the fifth day. In the thrombolysis group, with the patency of infarct related arteries, it dropped quickly (1-6 hours) after thrombolytic therapy; if the infarct related arteries were not patent, platelet GMP-140 increased rapidly after thrombolytic therapy and reached the highest at 6 hours, then it returned to baseline on the third day. It is suggested that the changes of platelet function could play an important role in thrombus formation and lysis; the rapid decrease of the number of GMP-140 molecules on platelet surface might be a new index for the pateacy of infarct related arteries.

Role of B61, the ligand for the Eck receptor tyrosine kinase, in TNF-alpha-induced angiogenesis

B61, a cytokine-inducible endothelial gene product, is the ligand for the Eck receptor protein tyrosine kinase (RPTK). Expression of a B61-immunoglobulin chimera showed that B61 could act as an angiogenic factor in vivo and a chemoattractant for endothelial cells in vitro. The Eck RPTK was activated by tumor necrosis factor-alpha (TNF-alpha) through induction of B61, and an antibody to B61 attenuated angiogenesis induced by TNF-alpha but not by basic fibroblast growth factor. This finding suggests the existence of an autocrine or paracrine loop involving activation of the Eck RPTK by its inducible ligand B61 after an inflammatory stimulus, the net effect of which would be to promote angiogenesis, a hallmark of chronic inflammation.

Characterization of B61, the ligand for the Eck receptor protein-tyrosine kinase

B61 was originally described as a novel secreted tumor necrosis factor-alpha-inducible gene product in endothelial cells (Holzman, L. B., Marks, R. M., and Dixit, V. M. (1990) Mol. Cell. Biol. 10, 5830-5838). It was recently discovered that soluble recombinant B61 could serve as a ligand for the Eck receptor protein-tyrosine kinase, a member of the Eph/Eck subfamily of receptor protein-tyrosine kinases (Bartley, T.D., Hunt, R. W., Welcher, A. A., Boyle, W. J., Parker, V. P., Lindberg, R. A., Lu, H. S., Colombero, A. M., Elliott, R. L., Guthrie, R. A., Holst, P. L., Skrine, J. D., Toso, R. J., Zhang, M., Fernandez, E., Trail, G., Yarnum, B., Yarden, Y., Hunter, T., and Fox, G. M. (1994) Nature 368, 558-560). We now show that B61 can also exist as a cell surface glycosylphosphatidyl-inositol-linked protein that is capable of activating the Eck receptor protein-tyrosine kinase, the first such report of a receptor protein-tyrosine kinase ligand that is glycosylphosphatidylinositol-linked. In addition, the expression patterns of B61 and Eck during mouse ontogeny were determined by in situ hybridization. Both were found to be highly expressed in the developing lung and gut, while Eck was preferentially expressed in the thymus. Finally, the gene for B61 was localized to a specific position on mouse chromosome 3 by interspecific back-cross analysis.

cDNA cloning and characterization of a Cek7 receptor protein-tyrosine kinase ligand that is identical to the ligand (ELF-1) for the Mek-4 and Sek receptor protein-tyrosine kinases

We have isolated a murine cDNA encoding a ligand for the Cek7 receptor protein-tyrosine kinase (RPTK), a member of the Eph/Eck RPTK subfamily. Sequence analysis predicts an open reading frame of 209 amino acids with a predicted molecular mass of 24 kDa. The Cek7 ligand shows a 48% sequence identity at the protein level to B61, a ligand for the related Eck RPTK, 30% to the Cek5 ligand, 59% to the recently cloned Ehk1-L, and identity to ELF-1, a recently described ligand for the Mek4 and Sek RPTKs. The expressed Cek7 ligand is functionally active as it induces autophosphorylation of the Cek7 RPTK.

Tilted amides in amino acid and peptide derivatives

BACKGROUND

Amide bonds in peptides and proteins typically adopt planar cis or trans conformations. Conversions between cis and trans amide conformations are necessary for protein folding and for many other processes, but are difficult to achieve since they involve disruption of the planarity of the bond. As a first step to understanding cis-trans isomerization, we set out to synthesize and characterize peptides that mimic the tilted or twisted amide structures that are postulated to form the intermediate states in this process.

RESULTS

We have synthesized a model amino acid and four dipeptide derivatives containing a methyl-substituted aziridine residue. Single crystals of phenacyl (2R, 3R)-benzyloxycarbonyl-3-methyl-2-aziridinecarboxylate and phenacyl (2R, 3R)-acetyl-glycyl-3-methyl-2-aziridine-carboxylate were obtained. Using X-ray diffraction analysis, we determined that the amide nitrogens of the aziridine rings have tetrahedral sp3-like geometry with tilt angles in the range of 37-38 degrees. The 13C-NMR spectra indicate that the amide carbonyl is dramatically shifted downfield as a consequence of the tilt.

CONCLUSIONS

In peptides containing a substituted aziridine ring, the orbitals of the amide nitrogen are constrained into a tilted configuration. These peptides may mimic the transition state between cis and trans amide conformations. This technique thus provides a novel strategy for the study of isomerization and other biorecognition processes.

cDNA cloning and characterization of a ligand for the Cek5 receptor protein-tyrosine kinase

We have isolated a murine cDNA encoding a ligand for the Cek5 receptor protein-tyrosine kinase (RPTK), a member of the Eph/Eck RPTK subfamily. Sequence analysis predicts an open reading frame of 345 amino acids with a predicted molecular mass of 38 kDa. Metabolic labeling and immunoprecipitation of cells transfected with a cDNA encoding the Cek5 ligand revealed the mature protein to have an apparent molecular mass of 45 kDa. The extracellular domain of the Cek5 ligand shows a 27% sequence identity at the protein level to B61, a ligand for the related Eck RPTK (Bartley, T. D., et al. (1994) Nature 368, 558-560). Consistent with the presence of a transmembrane domain, flow cytometry analysis revealed the Cek5 ligand to be expressed on the cell surface. The expressed Cek5 ligand is functionally active as it induces autophosphorylation of the Cek5 RPTK.

[Changes in fat absorption and effect of early enteral feeding following burn injury]

In order to approach this problem, a new animal model was developed in this study. Results indicated that the intestinal ability of absorbing nutrients was not markedly attenuated, and the reduction of portal blood flow was the primary cause of decrement of absorption of nutrients after burn injury. Therefore it is proposed that a timely and effective restoration of the portal circulation might improve the absorption ability. From the results of our present study, it seems probable that early enteral feeding can significantly increase the portal blood flow.

[Study on preserving intestinal function and the possible mechanism of hypermetabolic response following severe burn injury]

In order to approach the mechanism of hypermetabolic response following severe burn injury, a new animal model was developed with a specially bred miniswine (Guizhou species). Multiple catheterizations were applied for sampling different blood from portal, inferior mesenteric as will as jugular (central) veins. The animals were sustained with 30% III burn of TB-SA and divided randomly into early feeding group, given a complete diet beginning from 2 hours postburn (N = 6), and delayed feeding group, given the same diet initiating on 4 day postburn (N = 6). The results showed that compared with delayed feeding, early enteral feeding could strengthen the barrier function, decline the rate of translocation of bacteria and endotoxin from the gut to portal vein, reduce obviously blood TNF, CRP and catabolic-hormones, and significantly decrease REE (resting energy expenditure) and urinary 3-Mehis excretion. During the hypermetabolism (PBD7-10), the metabolic response mediated by "intestinal way" was at least 35%. The way of "intestinal tract--macrophages in liver--Hypermetabolism" is a possible mechanism of hypermetabolic response following severe burn injury, and the bacteria and endotoxin translocated from the gut, the active products (IL-1, TNF, etc) released by Kupffer's cells might be the mediating factors of the mechanism.

[Severe burn injury: glucose absorption and early enteral nutrition]

We investigated the changes of glucose absorption and the effect of early enteral nutrition after severe burn injury. A new animal model was developed with a specially bred miniswine (Gui Zhou species) to which multiple catheterizations were applied for sampling different blood from the portal, inferior mesenteric as well as jugular (central) veins. The animals were sustained with 30% III burns of TBSA 7 days after the catheterizations and divided randomly into early feeding (EF) group, given a complete diet beginning from 2 hours postburn, and delayed feeding (DF) group, given the same diet on 4 days postburn. After burn injury, glucose absorption was significantly decreased, but the absorption was much lower in group DF than that in group EF. However, the intestinal ability of absorbing nutrients was not attenuated greatly, and the reduction of portal blood flow was attributed to the decrease of absorption of nutrients. Early enteral feeding can increase portal blood flow obviously.

[Comparison of 0.1% dipivalyl epinephrine and 1% epinephrine in patients with glaucoma or ocular hypertension]

The effect of 0.1% dipivalyl epinephrine on intraocular pressure was compared with 1% epinephrine in patients with primary open-angle glaucoma or ocular hypertension. In this study, the two drugs significantly lowered intraocular pressure, with no significant differences being observed. In dipivalyl epinephrine group, no significant ocular or systemic adverse reactions, including heart rate and blood pressure, were observed except mild dilation of pupil.

B94, a primary response gene inducible by tumor necrosis factor-alpha, is expressed in developing hematopoietic tissues and the sperm acrosome

B94 was originally described as a novel tumor necrosis factor-alpha-inducible primary response gene in endothelial cells which was also induced in an in vitro model of angiogenesis. To further characterize its expression, we cloned the mouse homologue and mapped its developmental and tissue specific expression. The predicted amino acid sequence of mouse B94 was found to be 83% similar to its human homologue. The gene was localized to mouse chromosome 12 just centromeric to the immunoglobulin heavy chain locus, in a region that is often rearranged in T-cell neoplasms. To explore the possibility that B94 is expressed during vasculogenesis and other developmental processes, the expression of its transcript was determined during mouse development by in situ hybridization. In 10-day embryos B94 was expressed prominently in the myocardium and in the aortic arch. By the 15th day of gestation, expression was restricted largely to the liver, the bone forming regions of the jaw, the aortic endothelium, and the nasopharynx: a pattern that was maintained until just prior to birth. Postnatally, expression shifted to the red pulp of the spleen and the thymic medulla. B94 expression was extinguished in most adult tissues but was detectable in lymphopoietic tissues including the spleen, tonsil, and lymphatic aggregates in the gut. Consistent with this was the finding that mononuclear progenitor cells in bone marrow and mature peripheral blood monocytes expressed B94. A truncated testis-specific transcript previously identified by Northern blot analysis was determined to result from the use of an alternate polyadenylation signal which was surprisingly located within the open reading frame. This shorter transcript was expressed at high levels exclusively in late stage spermatids. Immunostaining with an affinity-purified polyclonal antiserum revealed B94 to be localized to the acrosomal compartment of mature sperm. These studies demonstrate that B94 expression is tightly regulated during development and suggests distinct roles for B94 in myelopoiesis and spermatogenesis.

[Preserving intestinal function after severe burn injury]

To study the changes of the bowel-barrier function and its preservation, we developed a new animal model. A specially bred miniswine (Guizhou species) was used with multiple catheterizations for sampling different blood from portal, inferior mesenteric as will as jugular (central) veins. The animals were sustained with 30% III burns of TBSA 7 days after catheterization and divided randomly into early feeding (EF) group, given a complete diet beginning from 2 hours postburn (n = 6) and delayed feeding (DF) group, given the same diet initiating on 4 days postburn (n = 6). The results indicated that the bowel-barrier function was weakened significantly early postburn so that the translocation of both endotoxin and bacteria from the gut to portal vein was evidently increased. However, improving the intestinal mucosa ischemia, preserving mucosal mass and maintaining bowel-microecological balance through early enteral feeding, as revealed in this study, could enhance the barrier function, and the translocation of bacteria and endotoxin would be thus decreased to some extent.

Effect of ethanol on development of fetal mouse thymocytes in organ culture

Exposure of mouse fetuses to ethanol in utero retards thymus development. The direct effect of ethanol on growth and differentiation of thymocytes was studied using organ cultures of 14-day fetal mouse thymuses. Fetal thymus organ cultures containing 0.2 or 0.4% ethanol produced fewer total thymocytes, proportionately fewer CD4+CD8+ (immature) thymocytes, and proportionately more CD4+CD8- (mature) cells than untreated control cultures after 5 days of culture. Total cell numbers and proportions of CD4+CD8+ thymocytes declined in a dose-dependent manner with increasing ethanol concentrations from 0.2 to 0.8%. In time course studies, thymuses cultured with 0.4% ethanol had an increased percentage of CD4+CD8- cells at all days examined between Days 4 and 6. In the same experiments, thymuses exposed to ethanol underwent accelerated loss of the interleukin-2 receptor (a marker of immature prothymocytes) and had higher percentages of cells positive for the gamma delta-T-cell receptor. Exposure to ethanol for 16 to 20 hr increased the percentage of noncycling thymocytes. Furthermore, ethanol increased apoptosis in fetal thymocytes. Acetaldehyde, the immediate product of ethanol catabolism, had no effect on thymocyte subpopulation ratios or cell numbers at a physiologic concentration (50 microM). Results indicate that in a controlled in vitro model of thymus development, ethanol reduced cell numbers and altered proportions of thymocyte subsets defined by differentiation antigens.

Ethanol increases apoptotic cell death of thymocytes in vitro

Exposure of animals to ethanol causes thymic atrophy in adults and fetuses. Whether direct effects of ethanol contribute to thymic atrophy or whether indirect effects are entirely responsible is at present unknown. In the normal animal, large numbers of thymocytes undergo a physiological form of cell death referred to as "apoptosis." To determine if ethanol affects the process of apoptosis, studies were undertaken in which mouse thymocytes were cultured overnight in the presence or absence of ethanol. Apoptotic cell death was analyzed by flow cytometric quantitation of apoptotic nuclei, by fluorometric measurement of DNA fragments, and by gel electrophoretic analysis of DNA fragments. Ethanol in concentrations of 0.2% to 0.8% produced significantly higher levels of apoptosis than were seen in control cultures. The DNA fragmentation was characterized as apoptotic on the basis of inhibition by aurintricarboxylic acid (an inhibitor of nucleases) and by the presence of characteristic oligonucleosomal-sized fragments of DNA. The effect of ethanol on apoptosis was additive to that induced by immobilized anti-CD3 monoclonal antibody. CD4+CD8+ cells underwent apoptosis as indicated by reduction in CD4 and CD8 surface antigen expression. An inhibitor of protein kinases (H-7) reduced the DNA degradation induced by ethanol and by anti-CD3. These results suggest that direct effects of ethanol contribute to thymic atrophy in alcohol-consuming animals.

A general method for chimerization of monoclonal antibodies by inverse polymerase chain reaction which conserves authentic N-terminal sequences

Chimerization of antibodies (Ab) by cloning the V (variable) regions encoding the light and heavy chains with degenerate oligodeoxyribonucleotide primers matching to framework region 1 and to the joining regions, leads to Ab with altered amino acids at the N-terminus compared to those of the parental Ab. This is due to N-terminal framework 1 sequences in the expression vectors [Larrick et al., Bio/Technology 7 (1989) 937-938; Le Boeuf et al., Gene (1989) 371-377; Orlandi et al., Proc. Natl. Acad. Sci. USA 86 (1989) 3833-3837]. This might lead to Ab with altered affinity to the antigen due to interaction of framework sequences with complementarity determining regions. Moreover, some V regions may be refractory to cloning by this procedure. Here, we describe a method to circumvent these potential problems. The V regions for both chains of the Ab are cloned by inverse polymerase chain reaction (PCR) with primers matching the known constant region sequences of the Ab. After sequencing, PCR fragments corresponding to the V regions of both chains are inserted in-frame into appropriate expression vectors leading to Ab with unaltered N-terminal sequences after expression in mammalian cells. The procedure is illustrated with an Ab directed against the beta chain of the human interleukin-2 receptor.

Analysis of human herpesvirus 6 glycoproteins recognized by monoclonal antibody OHV1

A virus-specific glycoprotein (gp) from human herpes-virus 6 (HHV-6) was studied using the anti-HHV-6 monoclonal antibody OHV1. Immunoprecipitation with extracts from infected cells revealed that the antibody recognized four glycosylated proteins (gps) with Mrs of 106K, 102K, 65K and 63K under reducing conditions. However, only two gps, of 106K (gp106) and 102K, were detected under non-reducing conditions. Pulse-chase experiments revealed that gp65 and gp63 were cleavage products of gp106 and gp102. When infected cells were treated with tunicamycin, none of these gps was detected. With endo-beta-N-acetylglucosaminidase H (endo H) and endo-beta-N-acetylglucosaminidase F (endo F) treatment, gp106 and gp102 disappeared. Moreover, gp65 and gp63 were not affected by endo H treatment but were sensitive to endo F treatment. These data suggest that sugar residues of gp106 and gp102 are high-mannose type N-linked oligosaccharides, whereas those of gp65 and gp63 are complex type N-linked oligosaccharides.

[Effect of lipoperoxide on catabolism of protein in burns in rats]

The effects of lipid peroxide on protein catabolism after severe burn injury are studied. Burned rats (30% TBSA III) were divided randomly into two groups: group A (N = 120) received I. M. injection of bovine serum albumin (BSA) served as control; group B (N = 146), the treated group, receiving I. M. injection of superoxide dismutase (SOD) and catalase (CAT). It was found that in PBD 5, 7, 9, 11, 3-Methyl histidine (3-Mehis) excretion was significantly lower in group B than in group A (P less than 0.01); and that in group B cumulative urinary nitrogen (UN) excretion and cumulative nitrogen balance in the eleven-day period after burns were significantly lower than in group A (P less than 0.01); On PBD 12, serum GOT and GPT were higher significantly in group A than that in group B (P less than 0.05). Besides, in group B the total nitrogen content in liver and gastrocnemius muscle on PBD 12 was significantly higher than in group A (P less than 0.05). These findings suggest that a certain relationship exists between lipoperoxide and increased protein catabolism after severe burns. SOD and CAT, the oxygen radical scavengers, can reduce protein catabolism to a certain extent, and protect the hepatic function from being injured.

Additivity of prostaglandin F2 alpha-1-isopropyl ester to timolol in glaucoma patients

The effect on intraocular pressure (IOP) of adding prostaglandin F2 alpha-1-isopropyl ester (PGF2 alpha-IE) to timolol was studied in 21 eyes of 13 patients with newly diagnosed primary open-angle glaucoma that was inadequately controlled with timolol alone. After at least 2 weeks of twice daily timolol 0.5% therapy, PGF2 alpha-IE, 0.5 microgram in 30 microliters, was topically applied twice daily at 8 AM and 8 PM, 5 minutes before each timolol dose, for 7 days. Intraocular pressures were measured before timolol treatment, and at 8 AM, 8:30 AM, 12 PM, 2 PM, and 4 PM on the day before the addition of PGF2 alpha-IE, and on day 1 and on day 7 of combined therapy. Mean IOP was 39 +/- 2 mmHg (+/- standard error) before timolol therapy and 31 +/- 2 mmHg after at least 2 weeks of treatment with timolol alone. A significant (P = 0.004) further reduction of IOP was first observed 4 hours after the first dose of PGF2 alpha-IE, which was maintained throughout the duration of combined therapy. During the last day of combined treatment and at 12 hours after the final dose, IOP was reduced a mean of 6 to 9 mmHg (mean, 9.0 +/- 1.5 mmHg at 12 hours) below baseline values obtained with timolol alone. These results indicate that adding PGF2 alpha-IE in patients treated with timolol causes a further reduction of IOP that may prove to be clinically useful in glaucoma therapy.

[The effect of topical metoprolol on intraocular pressure]

A single dose of topical 2% metoprolol, a new beta adrenergic antagonist, induced a significant IOP reduction in 20 normal volunteers (40 eyes) and 20 patients (40 eyes) with primary open angle glaucoma. The IOP of the latter 40 eyes remained significantly below the pretreatment levels during 6 months of continued application of the drug b.i.d. No changes were noted in pupil size, blood pressure, or heart rate, indicating that metoprolol is an effective ocular hypotensive.