bluuebunny/crossref_metadata_2025 huggingface dataset:
Vascular Thoracic Outlet Syndrome
Authors: Davidovic Lazar B. , Kostic Dusan M. , Jakovljevic Nenad S. , Kuzmanovic Ilija L. , Simic Tijana M.
Published: May 2003

Abstract

The surgical treatment of 30 cases of vascular thoracic outlet syndrome (TOS) in 25 patients is presented. Patients included 17 women and 8 men with average age of 26.1 years. The causes of compression were cervical rib (n = 16), soft tissue anomalies (n = 12), and scar tissue after clavicle fracture (n = 2). Ten subclavian artery aneurysms containing intraluminal thrombus as well as one subclavian artery occlusion were found. All such cases had multiple distal arterial embolization. Presenting features of cases with arterial TOS included: hand ischemia (n = 11), transient ischemic attack (TIA) (n = 1), and claudication or vasomotor phenomena during the arm hyperabduction (n = 11). Two patients with venous TOS developed hand edema during arm hyperabduction, and five other patients had axillary‐subclavian venous thrombosis. In all cases decompressive procedures using a combined supraclavicular and infraclavicular approach were performed. Decompression was achieved by cervical rib excision (n = 12), combined cervical and first rib excision (n = 4), and first rib excision (n = 14). In all cases division of all soft tissue elements was also accomplished. Associated vascular procedures included resection and replacement of 10 subclavian artery aneurysms, one subclavian‐axillary and one axillary‐brachial bypass, as well as nine brachial embolectomies. All five cases with axillary‐subclavian vein thrombosis before decompression were treated with anticoagulant therapy. The mean follow‐up period was 3 years and 2 months (range 1 to 6 years). Two pleural entry injuries and two transient brachial plexus injuries were noted. All reconstructed arteries were patent during the follow‐up period. Complete resolution of symptoms with a return to full activity was noticed in all cases with arterial TOS and in two cases with venous TOS without axillary‐subclavian vein thrombosis. In cases with axillary‐subclavian vein thrombosis relief of symptoms was mild, and there were limitations on daily activity. Vascular TOS is seen less frequently than the neurogenic form; however, in most cases it requires surgical treatment. We prefer a combined supraclavicular and infraclavicular approach because it offers complete exposure of the subclavian artery, cervical and first ribs, and all soft tissue anomalies.
Current Management of Pectus Excavatum
Authors: Fonkalsrud Eric W.
Published: May 2003

Abstract

Pectus excavatum (PE) is one of the most common anomalies of childhood. It occurs in approximately 1 in every 400 births, with males afflicted 5 times more often than females. PE is usually recognized in infancy, becomes much more severe during adolescent growth years, and remains constant throughout adult life. Symptoms are infrequent during early childhood, but become increasingly severe during adolescent years with easy fatigability, dyspnea with mild exertion, decreased endurance, pain in the anterior chest, and tachycardia. The heart is deviated into the left chest to varying degrees causing reduction in stroke volume and cardiac output. Pulmonary expansion is confined, causing a restrictive defect. Repair is recommended for patients who are symptomatic and who have a markedly elevated pectus severity index as determined by chest X‐ray or computed tomography scan. Repair using the highly modified Ravitch technique is usually performed after the age of 8 years. The optimal age for repair is between 12 and 16 years. Repair can be performed on adults with similar good results. Recent modifications in the Ravitch technique remove minimal cartilage and routinely use a temporary internal support bar for 6 months. Operation rarely takes more than 3 hours, and hospitalization rarely exceeds 3 days. Pain is mild and complications are rare, with 97% of patients experiencing a good to excellent result. The new minimally invasive Nuss repair avoids cartilage resection and takes less operating time, but is associated with more severe pain, longer hospitalization and a higher complication rate, with the bar remaining for 2 or more years. This technique is less applicable to older patients and those with asymmetric deformities. Long‐term follow‐up will be necessary to determine which operation may be best for any specific patient.
Mutations in the hydrophobic domain of poliovirus protein 3AB abrogate its permeabilizing activity
Authors: Lama Juan , Carrasco Luis
Published: May 2003

Poliovirus protein 3AB contains a predicted amphipathic helix that could lead to pore formation in membranes. We have introduced various mutations in the hydrophobic domain of the protein and the membrane‐modifying properties of the resulting mutants have been analyzed. Expression of wild type 3AB protein in E. coli increases the influx and efflux of different molecules such as nucleosides, lactose analogues and antibiotics. Thus, 3AB expression makes E. coli cells two orders of magnitude more sentitive to hygromycin B, a non‐permeant inhibitor of translation, and causes a 15‐20‐fold enhancement in the efflux of uridine. Changes in membrane permeability take place under conditions where no cellular lysis is detected and when other molecules such as β‐galactosidase or polyribonucleotides are kept inside the cell. These membrane modifications can be blocked to different extents by amino acid substitutions in the membrane‐spanning region of the protein. These results suggest that poliovirus protein 3AB could possess an intrinsic ability to form pores in natural membranes, thus allowing the flux of small hydrophylic molecules through them.
A novel enzyme, maltose 1‐epimerase from Lactobacillus brevis IFO 3345
Authors: Shirokane Yoshio , Suzuki Masaru
Published: May 2003

A novel enzyme, maltose 1‐epimerase (MER), that catalyzes the interconversion of α and β anomers of maltose was found in a cell‐free extract of Lactobacillus brevis IFO 3345, and MER was purified to homogeneity from the crude extract. The M
r of the enzyme was estimated to be 43,000 and 45,000 by HPLC gel filtration and SDS‐PAGE, respectively. It showed optimum activity at pH 6.5–7.0. This novel enzyme catalyzed the conversion of β‐maltose more effectively than disaccharides such as α‐lactose and β‐cellobiose, whereas the relative velocities for β‐ and α‐d‐glucose were about one forth of that for β‐maltose.
Upregulation of interleukin‐8 receptor in human polymorphonuclear neutrophils by formyl peptide and lipopolysaccharide
Authors: Manna Sunil K. , Samanta Ajoy K.
Published: May 2003

Interleukin‐8 (IL‐8) is implicated in the pathogenesis of a large number of neutrophil‐driven inflammatory diseases. Although the cytokine activates neutrophils through a receptor, no information is available regarding the regulation of IL‐8 receptor (IL‐8R) expression. The present study shows that, compared to control, the bacterial products — formylpeptide and LPS (serum‐activated) upregulate IL‐8 receptor by 54% and 115%, respectively, the former by degranulation of the secretory vesicle and the latter by de novo protein synthesis. The newly expressed IL‐8R could be demonstrated with anti‐IL‐8R‐antibody and by autoradiogram of the receptor crosslinked with [125I]IL‐8. The study may be useful for understanding the potential role of IL‐8 during neutrophil mediated inflammatory response.
Identification of the yeast methionine biosynthetic genes that require the centromere binding factor 1 for their transcriptional activation
Authors: Kuras Laurent , Thomas Dominique
Published: May 2003

The yeast Centromere binding factor I (Cbf1) belongs to the family of the DNA binding factors that recognize the consensus sequence CACGTG. Phenotypic studies of cells lacking Cbf1 revealed that this factor is actually involved in two cellular processes; the fidelity of the chromosomal segregation and the metabolism of sulfur amino acids. However, the function of Cbf1 in the regulation of the sulfur amino acid metabolism is now a matter of controversy in literature with conflicting reports about its binding to the CACGTG sequences found upstream to the methionine biosynthetic genes. To provide a reliable basis for the functional analysis of Cbf1, we present an analysis of the transcription of the methionine biosynthesic genes in cells lacking Cbf1. Our results prove that Cbf1 is indeed involved in the transcriptional regulation of the sulfur amino acid metabolism.
Bait region‐thiol ester mapping in human α2‐macroglobulin
Authors: Gettins Peter G.W. , Crews Brenda , Beth Albert H. , Hideg Kálmán
Published: May 2003

The separations between aromatic residues in the bait region and nitroxide spin labels attached to the thiol ester‐forming residues (Cys949 and Gln952) in human α
2‐macroglobulin (α
2M) have been determined from paramagnetic broadening effects of the spin labels on bait region 1H NMR signals. We found that both the Cys949 and Gln952 residues are within 11–17 Å of the aromatic residues in the bait region, with closer approach of some residues to the Gln952 spin label than to the spin label attached to Cys949. A model of the location of bait regions and thiol esters within an α
2M half‐molecule is proposed that places the bait regions in the central region of α
2M at the interface between the subunits.
The lipid body lipoxygenase from cucumber seedlings exhibits unusual reaction specificity
Authors: Feussner Ivo , Kühn Hartmut
Published: May 2003

The lipid body lipoxygenase of cucumber seedlings is at a high level expressed during the germinating process which is the stage of triglyceride mobilisation. This enzyme exhibits an unusual positional specificity which has not been described so far for any plant and animal lipoxygenase. The purified enzyme converts arachidonic acid to 15‐S‐hydroperoxy‐5Z,8Z,11Z, 13E‐eicosatetraenoic acid (15S‐HPETE), 12‐S‐hydroperoxy‐5Z, 8Z, 10E, 14Z‐eicosatetraenoic acid (12S‐HPETE), and 8‐S‐hydroperoxy‐5Z,9E,11Z,14Z‐eicosatetraenoic acid (8S‐HPETE) in a ratio of 76:4:20 with the corresponding R‐isomers being only minor contaminants. Binding to the lipid bodies enhances the arachidonic acid dioxygenase activity more than 4‐times and alters positional specificity of the enzyme in favour of 8‐S‐hydroperoxy‐5Z,9E,11Z,14Z‐eicosatetraenoic acid (8S‐HPETE) formation.
Amino acids 225–235 of the protein C serine‐protease domain are important for the interaction with the thrombin‐thrombomodulin complex
Authors: Vincenot A. , Gaussem P. , Pittet J.L. , Debost S. , Aiach M.
Published: May 2003

Protein C (PC) is a vitamin K‐dependent zymogen that inactivates factors Va and VIIIa after its activation by thrombin complexed to thrombomodulin. We characterized a monoclonal antibody (mAb) against PC, whose only influence on PC functions was to inhibit PC activation by the thrombin‐thrombomodulin complex. It recognized an epitope in the PC heavy chain, the conformation of which is calcium‐dependent. The mAb did not recognize a natural PC variant that was not activated by the thrombin‐thrombomodulin complex (mutation R229Q) and did recognize a synthetic peptide corresponding to PC amino acids 225–235 in an Elisa assay. The peptide inhibited PC activation by the thrombin‐thrombomodulin complex. These data confirm that the calcium‐binding loop of the serine‐protease domain is involved in the interaction of PC with the thrombin‐thrombomodulin complex.
Unreliability of carotenoid electrochromism for the measure of electrical potential differences induced by ATP hydrolysis in bacterial chromatophores
Authors: Crimi Massimo , Fregni Valeria , Altimari Annalisa , Melandri Bruno Andrea
Published: May 2003

ATP hydrolysis induces the activation of the proton ATPase in chromatophores of Rhodobacter capsulatus supplemented with nigericine and 50 mM K+ (i.e. when ΔpH < 0.2 units). The value of transmembrane electric potential (Δϕ) driving this activation was measured using three different approaches: carotenoid electrochromism, uptake of SCN− and responses of the dye oxonol VI. The value of Δϕ calculated from the SCN− uptake, on the basis of an internal volume determined experimentally, was about 140 mV, while that indicated by the electrochromic signal ranged between 35 and 70 mV. Only the value indicated by SCN‐ distribution is consistent with the energetic requirement for the activation of H+‐ATPase.
Peroxisomal‐microsomal communication in unsaturated fatty acid metabolism
Authors: Baykousheva Svetla P. , Luthria Devanand L. , Sprecher Howard
Published: May 2003

The addition of 1‐acyl‐sn‐glycero‐3‐phosphocholine (1‐acyl‐GPC) to peroxisomes decreased the production of acid‐soluble radioactivity formed by β‐oxidation of [1‐14C]arachidonate due to substrate removal by esterification into the acceptor. This peroxisomal‐associated acyl‐CoA:1‐acyl‐GPC acyltransferase activity was due to microsomal contamination. The production of acid‐soluble radioactivity from [1‐14C]7,10,13,16–22:4, but not from [3‐14C]7,10,13,16–22:4 was independent of 1‐acyl‐GPC, with and without microsomes. By comparing rates of peroxisomal β‐oxidation with those for microsomal acylation, it was shown that the preferred metabolic fate of arachidonate, when added directly to incubations, or generated via β‐oxidation, was esterification by microsomal 1‐acyl‐GPC acyltransferase, rather than continued peroxisomal β‐oxidation.
A pathway for the thermal destabilization of bacteriorhodopsin
Authors: Taneva Stefka G. , Caaveiro JoséM.M. , Muga Arturo , Goñi Félix M.
Published: May 2003

A variety of structural techniques, including IR spectroscopy, reveals that thermal denaturation of bacteriorhodopsin follows a given pathway (successively rearrangement of helical structures, extensive deuterium exchange, and finally protein aggregation) irrespective of heating rate, pH or ionic strength conditions. In all cases, thermal denaturation leads to a ‘compact denatured state’ which retains a large proportion of ordered structure.
Two distinct inwardly rectifying conductances are expressed in long term dibutyryl‐cyclic‐AMP treated rat cultured cortical astrocytes
Authors: Ferroni Stefano , Marchini Cristina , Schubert Peter , Rapisarda Carmela
Published: May 2003

Long term incubation (1–3 weeks) with 250 μM dibutyryl‐cyclic‐AMP (dBcAMP) of pure cultured cortical astrocytes from newborn rats leads to the expression of voltage‐dependent, inward‐rectifying potassium (K+) and chloride (Cl−) currents which are lacking in shortly treated (4–24 h) and in control cultured astrocytes. Both conductances are already activated at the holding potential of −60 mV and are distinguishable for their gating kinetics and pharmacological sensitivity. K+ currents have a fast activation kinetic and show a time‐ and voltage‐dependent inactivation at potentials negative to −120 mV. The conductive property of the K+ currents increases upon elevation of the extracellular K+ concentration ([K+]0) and they are reversibly blocked by extracellular 0.1 mM barium ions (Ba2+). Cl− currents are activated only at negative membrane potentials; they display a slow activation kinetic, no time‐dependent inactivation and are not affected by 0.1 mM Ba2+. In individual astrocyte the K+ and Cl− conductances can be expressed singularly or in combination. The results indicate that the expression of these two conductances is controlled by a cAMP‐dependent molecular signalling, presumably by regulating a late gene activation. Thus, the strengthening of this signalling would contribute to promote the maturation of less differentiated astrocytes in culture, implicating the expression of K+ and Cl− membrane conductances which may operate together in the regulation of [K+]0 homeostasis via the mechanism of the local accumulation.
Tubulin‐tyrosine ligase catalyzes covalent binding of 3‐fluoro‐tyrosine to tubulin: kinetic and [19F]NMR studies
Authors: Monasterio Octavio , Nova Esteban , López-Brauet Adamari , Lagos Rosalba
Published: May 2003

The use of 3‐fluoro‐tyrosine as an alternative substrate for the enzyme tubulin:tyrosine ligase which catalyzes the incorporation of tyrosine into the α‐tubulin subunit was investigated. The incorporation of tyrosine into tubulin was inhibited competitively by 3‐fluoro‐tyrosine with an apparent K
i of ∼ 25 μM. The affinity for this analog was similar to that of tyrosine, confirming that the hydrogen at position 3 of the aromatic ring is not essential for the reaction catalyzed by TTLase. The incorporation of 3‐fluoro‐tyrosine into the C‐terminus of the α‐turbulin subunit was demonstrated through [19F]NMR spectroscopy. The 3‐fluoro‐tyrosine signal at −58.6 ppm (trifluoroacetic acid as external standard), with a bandwidth of 24.7 Hz presented a chemical shift of 0.75 ppm upfield and an enlargement in the bandwidth (30.5 Hz) when incorporated into tubulin. These results strongly suggest that this amino acid is exposed to the solvent in tubulin. Tubulin covalently labeled with 3‐fluoro‐tyrosine was competent to polymerize into microtubules. The use of fluorinated tubulin in [19F]NMR spectroscopy for studying questions concerning protein conformation and interactions will be discussed.
Calcium controls phage T5 infection at the level of the Escherichia coli cytoplasmic membrane
Authors: Bonhivers Mélanie , Letellier Lucienne
Published: May 2003

Phage T5 requires 0.1 mM calcium to produce phage progeny in Escherichia coli cells. Decreasing calcium below 0.1 mM at time phage DNA was transferred depleted the bacteria of K+, caused membrane depolarization, perturbation of phage DNA transfer and resulted in a low internal ATP level. Our data suggest that calcium controls the conformation of the channel involved in the transfer of phage DNA through the host envelope and that below 0.1 mM calcium the channel remains open. This creates an energetic state of the host unfavorable to the synthesis of phage components and leads to abortion of the infectious process.
Characterization of the cleavage specificity of a subtilisin‐like serine proteinase from Ophiostoma piceae by liquid chromatography/mass spectrometry and tandem MS
Authors: Abraham Linda D. , Chow David T. , Breuil Colette
Published: May 2003

A proteinase secreted by the sapstaining fungus Ophiostoma piceae is thought to be necessary for the primary retrieval of nitrogen from wood proteins. By using mass spectrometry (MS) techniques, we have estabilished the cleavage specificity of this subtilisin‐like serine proteinase. This work demonstrated the potential of MS in determining cleavage specificities of newly isolated proteinases in a relatively short time frame, and determined that the O. piceae proteinase showed a substrate specificity similar to that of proteinase K. Primary cleavage of the insulin B‐chain occurred between Leu15 and Tyr16. In addition numerous secondary cleavage sites occurred after hydrophobic, polar, and charged amino acids indicating a broad specificity.
Insulin stimulates hormone‐sensitive cyclic GMP‐inhibited cyclic nucleotide phosphodiesterase in rat brown adipose cells
Authors: Omatsu-Kanbe Mariko , Cushman Samuel W. , Manganiello Vincent C. , Taira Masato
Published: May 2003

The presence and regulation of a hormone‐sensitive cyclic GMP‐inhibited cyclic nucleotide phosphodiesterase (cGI PDE) in rat brown adipose cells was investigated. cDNA clones for two cGI PDE isoforms, cGIP1 and cGIP2, have been isolated. Using a rat cGIP1 (RcGIP1) cDNA probe, RcGIP1 mRNA (∼5.3 kb) was detected in Northern blots of both brown and white adipose RNA. cGI PDE was detected in both microsomal and plasma membrane fractions of brown and white adipose cells by Western blotting using anti‐RcGIP1 peptide antibody. When cells were incubated with insulin before membrane preparation, cGI PDE activity in the microsomal fraction was increased by 2‐ to 2.5‐fold within 10 min. Isoproterenol also stimulated the activity of cGI PDE in the microsomal fraction by 1.5‐fold. In cells incubated with both insulin and isoproterenol, microsomal cGI PDE activity was similar to that in microsomal fractions isolated from cells incubated with insulin alone. These results suggest that the hormonal regulation of cGI PDE, presumably a cGIP1 isoform, in rat brown adipose cells is similar to that in white adipose cells.
Helix‐loop‐helix transcription factors regulate Id2 gene promoter activity
Authors: Neuman Külliki , Nornes Howard O. , Neuman Toomas
Published: May 2003

Id‐like helix‐loop‐helix (HLH) transcription factors are involved in the regulation of proliferation and differentiation of several cell types. We isolated 5′ regulatory region of mouse Id2 gene and demonstrated that it contains several E‐box clusters. These E‐boxes mediate stimulatory effects of basic‐HLH (bHLH) transcription factors ME1, ME2, and NSCL1 on Id2 promoter activity. Co‐expression of Id2 blocks the stimulatory effect of bHLH transcription factors which suggests the presence of feedback loops in Id2 transcriptional regulation. Overexpression of NSCL1 in F9 cells blocks the downregulation of Id2 gene expression during retinoic acid induced differentiation. Our data demonstrate that bHLH transcription factors regulate Id2 gene expression.
Coactosin interferes with the capping of actin filaments
Authors: Röhrig Ursula , Gerisch Günther , Morozova Ludmilla , Schleicher Michael , Wegner Albrecht
Published: May 2003

Coactosin, a 16 kDa protein associated with the actin cytoskeleton from Dictyostelium discoideum, was purified by an improved method, in which other components of the cytoskeleton were removed. The highly purified coactosin had no effect on the time course of actin polymerization, but when added to actin in presence of capping proteins, coactosin counteracted the capping activity of these proteins. The capping proteins cap32/34 and severin domain 1 retarded actin polymerization, on addition of coactosin to samples containing one of these capping proteins the time course of actin polymerization became close to controls without capping proteins.
Up‐regulation of endothelial nitric oxide synthase expression by cyclic guanosine 3′,5′‐monophosphate
Authors: Ravichandran Lingamanaidu V. , Johns Roger A.
Published: May 2003

In this study, the role of cyclic GMP, the end product of the NO‐cyclic GMP signalling pathway, in the regulation of ecNOS was investigated. Bovine pulmonary endothelial cells were exposed to 8‐bromo‐cyclic GMP and its effect on NO production, ecNOS protein, and mRNA levels was analyzed. Endothelial cells on exposure to 8‐bromo‐cyclic GMP produced significantly increased amounts of NO, detected as increased cyclic GMP in cocultures with vascular smooth muscle cells both under basal conditions and with agonist stimulation. 8‐Bromo‐cyclic GMP significantly increased the ecNOS protein and mRNA levels as detected on Western and Northern blots respectively. This 8‐bromo‐cyclic GMP mediated increase of NO production, ecNOS protein and mRNA levels suggests that cyclic GMP up‐regulates the expression of ecNOS. Thus, there may be an intercellular feedback mechanism involved at the molecular level in the expression of the NO‐cyclic GMP signalling pathway in blood vessels.
Identification of a regulatory phosphorylation site in the hinge 1 region of nitrate reductase from spinach (Spinacea oleracea) leaves
Authors: Douglas Pauline , Morrice Nick , MacKintosh Carol
Published: May 2003

Purified nitrate reductase (NR) from spinach leaves was phosphorylated in vitro by NR‐inactivating kinase on Ser‐543 which is located in the hinge 1 region between the molybdenum‐cofactor and haem‐binding domains. Phosphorylation of Ser‐543 allowed NR to be inhibited by the inhibitor, NIP. Degraded NR preparations in which a proportion of the subunits had lost 45 amino acids from the N‐terminus during purification could be phosphorylated by NR kinase on Ser‐543, but could not subsequently be fully inhibited by NIP, suggesting a role for the N‐terminal tail of NR in NIP binding.
The β1‐subunit is essential for modulation by protein kinase C of an human and a non‐human L‐type Ca2+ channel
Authors: Bouron Alexandre , Soldatov Nikolai M. , Reuter Harald
Published: May 2003

We have investigated in Xenopus oocytes the effects of phorbol ester‐induced protein kinase C (PKC) stimulation on dihydropyridine (DHP)‐insensitive and ‐sensitive Ca2+ channels. DHP‐insensitive Ba2+ currents (I
Ba) were recorded from endogenous channels in non‐injected oocytes and in oocytes injected with cRNAs encoding the auxiliary rabbit α
2/δ and β
1 Ca2+ channel subunits. A human α
1C cRNA, injected alone or in combination with cRNAs of the auxiliary subunits, was used for studying DHP‐sensitive I
Ba. We found that DHP‐insensitive I
Ba was increased by 4β‐phorbol 12‐myristate 13‐acetate (PMA), while DHP‐sensitive I
Ba was decreased. In both cases, the effects depended only on the co‐expression of the β
1 subunit.
Time‐resolved solid‐state REDOR NMR studies of UDP N‐acetylglucosamine enolpyruvyl transferase
Authors: Li Yan , Krekel Florian , Ramilo Cecilia A. , Amrhein Nikolaus , Evans Jeremy N.S.
Published: May 2003

The new method of time‐resolved solid‐state rotational echo double resonance (REDOR) NMR spectroscopy introduced recently by this laboratory has been applied to the enzyme uridine N‐acetylglucosamine (UDP‐NAG) enolpyruvyl transferase (EPT), with the goal of probing the interactions between reactive species and their enzyme active site. The approach has been used in a qualitative fashion with the enzyme‐inhibitor and enzyme‐intermediate complexes of uniformly 15N‐labeled UDP‐NAG EPT, trapped under steady‐state and pre‐steady‐state conditions. A different set of intermolecular interactions between the substrates UDP‐NAG, UDP‐NAG plus 3‐Z‐fluorophosphoenolpyruvate, covalent O‐phosphothioketal, and UDP‐NAG plus phosphoenolpyruvate trapped under time‐resolved conditions (after 50 ms reaction time), and the EPT enzyme active site were observed, and this is contrasted to a similar study of the interactions in a related enzyme, 5‐enolpyruvyl‐shikimate‐3‐phosphate synthase.
Arginine‐427 in the Na+/glucose cotransporter (SGLT1) is involved in trafficking to the plasma membrane
Authors: Lostao M.Pilar , Hirayama Bruce A. , Panayotova-Heiermann Mariana , Sampogna Sharon L. , Bok Dean , Wright Ernest M.
Published: May 2003

To investigate the role of charged intramembrane residues in the function of the rabbit Na+/glucose cotransporter (rbSGLT1) we substituted arginine‐427 (R427) by alanine in the putative domain M9 SGLT1. This residue is conserved in all the members of the SGLT1 family. The mutant protein (R427A) was expressed in Xenopus oocytes and, although Western blot analysis revealed that it was produced in amounts comparable to wildtype, no function was measured. Freeze‐fracture analysis showed that R427A SGLT1 was not in the plasma membrane while immunocytochemical experiments localized the transporter to just beneath it. These results indicate that arginine‐427 plays a critical role in SGLT1 trafficking to the plasma membrane.
Ketoconazole and other imidazole derivatives are potent inhibitors of peroxisomal phytanic acid α‐oxidation
Authors: Pahan Kalipada , Khan Mushfiquddin , Smith Brian T. , Singh Inderjit
Published: May 2003

The imidazole antimycotics like ketoconazole, clotrimazole, bifonazole, miconazole and CO, known as powerful inhibitors of cytochrome P‐450, are potent inhibitors of peroxisomal phytanic acid α‐oxidation to pristanic acid suggesting the possible involvement of the cytochrome P‐450 mono‐oxygenase system in this oxidation. In contrast to the inhibition of the oxidation of [1‐14C]phytanic acid, [1‐14C]phytanoyl‐CoA and [(2,3)‐3H]phytanic acid, these drugs and CO have no effect on the oxidation of [1‐14C]α‐hydroxy phytanic acid indicating that these drugs and CO inhibit only the α‐hydroxylation of phytanic acid. These studies using purified peroxisomes from liver and cultured human skin fibroblasts and Hep G2 cells clearly demonstrate that α‐hydroxylation, an intermediate step in the α‐oxidation of phytanic acid found to be impaired in Refsum Disease, is mediated by cytochrome P‐450 containing enzyme.
Phylogenetic, structural and functional analyses of the LacI‐GalR family of bacterial transcription factors
Authors: Nguyen Chuck Chuong , Saier Milton H.
Published: May 2003

Phylogenetic tree construction for 25 sequenced members of the LacI‐GalR family (LGF) of transcription factors revealed that almost all branches are similar in length, radiating essentially from a single point. This observation suggests that most of these proteins arose by duplication events which occurred at a specific time in evolutionary history, and that further duplication events were rare. Analyses of the multiple alignment of the LGF proteins lead to suggestions regarding structure‐function relationships and reveal that the helix‐turn‐helix DNA‐binding motif of LGF proteins is similar in sequence to those of numerous non‐homologous DNA‐binding proteins.
A novel partner for the GTP‐bound forms of rho and rac
Authors: Madaule Pascal , Furuyashiki Tomoyuki , Reid Tim , Ishizaki Toshimasa , Watanabe Go , Morii Narito , Narumiya Shuh
Published: May 2003

Using the yeast two hybrid system and overlay assays we identified a putative rho/rac effector, citron, which interacts with the GTP‐bound forms of rho and rac1, but not with cdc42. Extensive homologies to known proteins were not observed. This 183 kDa protein contains a C6H2 zinc finger, a PH domain, and a long coiled‐coil forming region including 4 leucine zippers and the rho/rac binding site. We recently identified three others putative rho effectors characterized by a common rho binding motif. Citron does not share this motif and displays a distinctive protein organization, thus defining a separate class of rho partners.
Phylogenetic classification of the major superfamily of membrane transport facilitators, as deduced from yeast genome sequencing
Authors: Nelissen Bart , Mordant Philippe , Jonniaux Jean-Luc , Wachter Rupert De , Goffeau André
Published: May 2003

From the approximately 5000 open reading frames presently identified by systematic sequencing of the yeast genome, 100 Saccharomyces cerevisiae transport proteins belonging to the major facilitator superfamily (MFS), were assigned to 17 families on the basis of extensive database searches and binary comparisons. These families include multidrug resistance proteins and transport proteins for sugars, amino acids, uracil/allantoin, allantoate, phosphate, purine/cytosine, proteins, peptides, potassium, sulfate, and urea. Four new families of unknown function have been identified. For the sugar and amino acid transport proteins, alignments were made and phylogenetic trees were constructed allowing the identification of several clusters of proteins presumably exhibiting similar transport functions.
The role of glutathione in the transport and catabolism of nitric oxide
Authors: Hogg Neil , Singh Ravinder J. , Kalyanaraman B.
Published: May 2003

Nitric oxide acts as a neuronal and vascular messenger implying diffusion through intracellular environments containing 5–10 mM glutathione. Nitric oxide reacts with glutathione under aerobic conditions generating S‐nitrosoglutathione (GSNO). GSNO reacts with glutathione (k = 8.3 × 10−3 M−1 · s−1) to generate nitrous oxide and glutathione disulfide (GSSG). Anaerobically, glutathione reacts with nitric oxide generating nitrous oxide and GSSG (k = 4.8 × 10−4 s−1 at 5 mM GSH). In both aerobic and anaerobic situations the nitroxyl anion may be an intermediate in the synthesis of nitrous oxide and, under aerobic conditions, nitroxyl anion may generate peroxynitrite. We present a hypothesis for the intracellular interaction between nitric oxide and glutathione.
The H+‐ATPase purified from maize root plasma membranes retains fusicoccin in vivo activation
Authors: Marra Mauro , Fogliano Vincenzo , Zambardi Alessandra , Fullone Maria Rosaria , Nasta Daniela , Aducci Patrizia
Published: May 2003

The activity of ‘P‐type’ ATPases is modulated through the C‐terminal autoinhibitory domain. The molecular bases of this regulation are unknown. Their understanding demands functional and structural studies on the activated purified enzyme. In this paper the plasma membrane H+‐ATPase from maize roots activated in vivo by fusicoccin was solubilised and fractionated by anion‐exchange HPLC. Results showed that the H+‐ATPase separated from fusicoccin receptors retained fusicoccin activation and that it was more evident after enzyme insertion into liposomes. These data suggest that fusicoccin stimulation does not depend on a direct action of the fusicoccin receptor on the H+‐ATPase, but rather, fusicoccin brings about a permanent modification of the H+‐ATPase which very likely represents a general regulatory mechanism for ‘P‐type’ ATPases.
T7 DNA‐dependent RNA polymerase can transcribe RNA from tick‐borne encephalitis virus (TBEV) cDNA with SP6 promoter
Authors: Dobrikova E.Yu. , Pletnev A.G. , Karamyshev V.N. , Morozova O.V.
Published: May 2003

T7 RNA polymerase is shown to recognize the SP6 promoter including 17 base pairs before the transcription start site and produce the 5′‐end TBEV RNA. The yield of TBEV RNA synthesized by heterologous T7 RNA polymerase from cDNA construction with SP6 promoter is higher than the RNA production by homologous SP6 RNA polymerase. The addition of 1 pmol template DNA with SP6 17 bp promoter in transcription mixture for SP6 or T7 RNA polymerases resulted in 1–5 × 10−2 pmol RNA production.
A benzothiophene‐carboxamide is a potent inhibitor of IL‐1β induced VCAM‐1 gene expression in human endothelial cells
Authors: Cobb Ronald R. , Felts Katherine A. , McKenzie Thomas C. , Parry Graham C.N. , Mackman Nigel
Published: May 2003

Vascular endothelial cells respond to cytokines such as IL‐1β or TNF‐α by undergoing a number of functional alterations. Among these alterations is the induction of cell surface adhesion molecules, including VCAM‐1. In this report, we investigated the effects of a 3‐alkoxybenzo[β]thiopene‐2‐carboximide (BZT) on the cytokine induction of VCAM‐1 expression and activation of the transcription factor NF‐κB in human endothelial cells. BZT blocked the IL‐1β induced cell surface expression of VCAM‐1 in human endothelial cells but did not prevent nuclear translocation of NF‐κB. This study demonstrates that BZT is a potent inhibitor of VCAM‐1 expression in human endothelial cells.
Hybrid structures and improving forecasting and scheduling in project management
Authors: Pollack‐Johnson Bruce
Published: May 2003

In many areas of managerial decision‐making and analysis, there are classical dichotomies, such as subjective versus objective forecasting methods, short‐range versus long‐range forecasting, heuristic versus optimization algorithms, and logic programming versus functional programming. This article describes some hybrid concepts and techniques that attempt to synthesize the strengths and minimize the weaknesses of seemingly incompatible classical approaches to problems that are central to project management and scheduling and to operations management in general.
Internal auctions for the efficient sourcing of intermediate products
Authors: Bushnell James B. , Oren Shmuel S.
Published: May 2003

We examine the problem of setting production levels and selecting an internal supplier for a vital intermediate product. These decisions are being made in a decentralized environment involving internal suppliers that are profit centers with private cost information. Our analysis centers on the use of multi‐dimensional auctions for facilitating communication between divisions and for implementing efficiency goals. We demonstrate analytically what the efficiency goals of the purchasing division should be and characterize necessary conditions of the auction process for implementing those efficiency goals.
The impact of capacity expansion on the market value of the firm
Authors: Hendricks Kevin B. , Singhal Vinod R. , Wiedman Christine I.
Published: May 2003

This paper empirically investigates the impact of capacity expansion decisions on the market value of the firm. Event study methodology is used to estimate the abnormal change in stock prices around capacity expansion decision announcements. On the day of the announcement, the magnitude of the price change is abnormally high, evidenced by a significantly positive mean standardized square of the abnormal change (Beaver's U‐statistic). We also analyze factors that we could affect the direction and magnitude of the abnormal change in the stock prices. We find that the change in price on the day of the announcement is positively and significantly related to the real growth rate of the industry, and negatively and significantly related to the variability of demand. A negative relationship between the price change and industry capacity utilization is also found which can have important implications for companies which follow the wait‐and‐see approach to capacity expansion decisions. We also find management ownership to be a significant predictor in explaining stock price changes around these announcements.
Flexibility as process mobility: The management of plant capabilities for quick response manufacturing
Authors: Upton David M.
Published: May 2003

This paper examines the relationship between one form of manufacturing flexibility ‐ operational mobility (or the ability to change quickly between products) ‐ and structure, infrastructure and managerial policy at the plant level. Using data from a broader study aimed at exploring the general sources of manufacturing flexibility, the paper provides evidence of the strength of the links between manufacturing flexibility and such factors as scale, technology vintage, computer integration and workforce management. There has been little empirical work on this subject, partly as a result of the difficulties of defining and measuring flexibility. The type of flexibility explored in this paper is specifically the capability of a plant to change between process states quickly.

I find that most of the variance in flexibility across plants can be explained by a combination of structural factors, such as the scale of the plant; infrastructural factors, such as the length of service of the operators; and measures of managerial emphasis, such as the perceived importance of making quick changeovers. Of these factors, I find that the scale of a plant does not strongly inhibit its flexibility and that computer integration is either insignificant or detrimental to the flexibility of a plant. Workforce characteristics are also important determinants of flexibility, and the results suggest that less experienced operators may be more flexible in their ability to make certain types of change quickly between products. A strong determinant of the flexibility of a plant is the extent to which operators perceive managers to have emphasized the importance of various performance dimensions.

Finally, I show that different forms of flexibility are not necessarily related to each other. This emphasizes the importance of identifying precisely the particular type of flexibility that is to be developed when building manufacturing capabilities.
Coordination in operations: A taxonomy
Authors: Whang Seungjin
Published: May 2003

This paper proposes a taxonomy of coordination study in operations. Its point of departure is the assumption that coordination study in operations always involves a “system” which can be a mathematical model, a software system, a business process or a game. A system is the unit of analysis in the taxonomy. In the taxonomy, systems are first divided into three categories depending on the type of coordination ‐ coordination within operations, cross‐functional coordination and inter‐organizational coordination. Systems are further divided depending on how people in the organization behave, i.e., the perspective of organization. We propose three alternative perspectives of organization ‐ single‐person perspective, team perspective, and nexus‐of‐contract perspective of organization. Through a series of examples, we describe nine subcategories of systems.
The operating impact of parts commonality
Authors: Vakharia Asoo J. , Parmenter David A. , Sanchez Susan M.
Published: May 2003

This paper investigates the impact of between‐ and within‐product parts commonality on the workload of a manufacturing firm using an MRP system. More specifically, we investigate the impact of several operational factors and their interactions with part commonality. We develop and validate a large simulation of an MRP system and integrate the generation of planned order releases with workload estimation on the shop floor. The results indicate that increasing parts commonality has positive effects in terms of average shop load but does lead to greater variability in terms of loadings as well as increasing system disruption. Further, we also find that the number of work centers significantly impacts the shop floor effects of commonality. Hence, although an increase in parts commonality results in less design effort and increased standardization, the negative effects of increasing commonality often appear on the shop floor level. This points to a need for the effective management of parts commonality by assessing the tradeoff between strategic “benefits” and operational “costs”.
The Methanocaldococcus jannaschii protein Mj0968 is not a P‐type ATPase
Authors: Bramkamp Marc , Gaßel Michael , Herkenhoff-Hesselmann Brigitte , Bertrand Jessica , Altendorf Karlheinz
Published: May 2003

The Methanocaldococcus jannaschii (formerly Methanococcus jannaschii) protein Mj0968 has been reported to represent a soluble P‐type ATPase [Ogawa et al., FEBS Lett. 471 (2000) 99–102]. In this study, we report that the heterologously expressed Mj0968‐His10 protein exhibits high rates of phosphatase activity, whereas only very low ATPase activity was measured. Replacement of the aspartate residue in the DSAGT motif (D7A), which becomes phosphorylated during the reaction cycle of P‐type ATPases, does not affect the V
max, but only the K
M of the reaction. Labeling studies with [γ‐32P]ATP and [α‐32P]ATP revealed that the previously reported labeling experiments [Ogawa et al., 2000] do not necessarily show phosphorylation of Mj0968, but rather point to ATP binding. Binding studies with trinitrophenyl adenosine nucleotides showed low apparent K
d values for those molecules. These results provide evidence that the native function of Mj0968 seems to be that of a phosphatase, rather than that of an ATP‐hydrolyzing enzyme.
Transcriptional effects of the signal transduction protein PII (glnB gene product) on NtcA‐dependent genes in Synechococcus sp. PCC 7942
Authors: Paz-Yepes Javier , Flores Enrique , Herrero Antonia
Published: May 2003

PII proteins signal the cellular nitrogen status in numerous bacteria, and in cyanobacteria PII is subjected to serine phosphorylation when the cells experience a high C to N balance. In the unicellular cyanobacterium Synechococcus sp. PCC 7942, the PII protein (glnB gene product) is known to mediate the ammonium‐dependent inhibition of nitrate and nitrite uptake. The analysis of gene expression through RNA/DNA hybridization indicated that a PII‐null mutant was also impaired in the induction of NtcA‐dependent, nitrogen assimilation genes amt1 (ammonium permease), glnA (glutamine synthetase) and nir (nitrite reductase), as well as of the N‐control gene ntcA, mainly under nitrogen deprivation. This gene expression phenotype of the glnB mutant could be complemented by wild‐type PII protein or by modified PII proteins that cannot be phosphorylated and mimic either the phosphorylated (GlnBS49D and GlnBS49E) or unphosphorylated (GlnBS49A) form of PII. However, strains carrying the GlnBS49D and GlnBS49E mutant proteins exhibited higher levels of expression of nitrogen‐regulated genes than the strains carrying the wild‐type PII or the GlnBS49A protein.
The A‐type ATP synthase subunit K of Methanopyrus kandleri is deduced from its sequence to form a monomeric rotor comprising 13 hairpin domains
Authors: Lolkema Juke S. , Boekema Egbert J.
Published: May 2003

The ntpK gene of the archaeon Methanopyrus kandleri encodes the equivalent of the c subunit of ATP synthase. The gene product contains 1021 residues and consists of 13 homologous domains, each one corresponding to a single helical hairpin. The amino acid sequence of the domains is highly conserved, ranging between 50 and 80% sequence identity. Each of the 13 domains contains a conserved Gln and Glu residue in the N‐ and C‐terminal helix, respectively, both of which are believed to be involved in cation binding. The protein is likely to form the monomeric rotor of the ATP synthase that consists of 13 hairpin domains.
Is a Q‐cycle‐like mechanism operative in dihaemic succinate:quinone and quinol:fumarate oxidoreductases?
Authors: Pereira Manuela M. , Teixeira Miguel
Published: May 2003

Succinate:quinone (SQR) and quinol:fumarate oxidoreductases (QFR) are members of the same enzyme family. These are membrane bound enzymes anchored to the membrane by one or two subunits that may contain two, one or no haems. For the dihaemic enzymes the electron pathway from the flavin at the catalytic centre to the quinones remains to be established. Taking into account that the two haems are located on opposite sites of the membrane, and the possible presence of two quinone binding sites, also located on opposite sides of the membrane, we re‐hypothesise the presence of a Q‐cycle type mechanism in these enzymes. Such a mechanism can explain an active functional role for two haems and two quinone binding sites, allowing SQR to conserve energy. With this testable hypothesis we intend to challenge the discussion and drive further experimentation to unravel the functional mechanism of SQRs and QFRs.
Transcriptional repression of cyclin‐dependent kinase inhibitor p21 gene by phospholipase D1 and D2
Authors: Kwun Hyun Jin , Lee Jae Hwa , Min Do Sik , Jang Kyung Lib
Published: May 2003

Phospholipase D (PLD) is known to stimulate cell cycle progression and to transform murine fibroblast cells into tumorigenic forms, although the precise mechanisms are not elucidated. In this report, we demonstrated that both PLD1 and PLD2 repressed expression of cyclin‐dependent kinase inhibitor p21 gene in an additive manner. The phospholipase activity of PLDs was important for the effect. PLD1 repressed the p21 promoter by decreasing the level of p53, whereas PLD2 via a p53‐independent pathway through modulating Sp1 activity. Taken together, we suggest that PLD isozymes stimulate cell growth by repressing expression of p21 gene, which may ultimately lead to carcinogenesis.
NMR studies of the fifth transmembrane segment of sarcoplasmic reticulum Ca2+‐ATPase reveals a hinge close to the Ca2+‐ligating residues
Authors: Nielsen Gerd , Malmendal Anders , Meissner Axel , Møller Jesper V , Nielsen Niels Chr
Published: May 2003

Two recent X‐ray structures have tremendously increased the understanding of the sarco/endoplasmic reticulum Ca2+‐ATPase (SERCA) and related proteins. Both structures show the fifth transmembrane span (M5) as a single continuous α‐helix. The inherent structural and dynamic features of this span (Lys758–Glu785) were studied in isolation in sodium dodecyl sulfate (SDS) micelles using liquid‐state nuclear magnetic resonance (NMR) spectroscopy. We find that a flexible region (Ile765–Asn768) is interrupting the α‐helix. The location of the flexible region near the Ca2+ binding residues Asn768 and Glu771 suggests that together with a similar region in M6 it has a hinge function that may be important for cooperative Ca2+ binding and occlusion.