bluuebunny/crossref_metadata_2025 huggingface dataset:
Oral cladribine for B‐cell chronic lymphocytic leukaemia: report of a phase II trial with a 3‐d, 3‐weekly schedule in untreated and pretreated patients, and a long‐term follow‐up of 126 previously untreated patients
Authors: Karlsson Karin , Strömberg Mats , Liliemark Jan , Delannoy André , Johnson S. A. N. , Porwit Anja , Kimby Eva , Lärfars Gerd , Cristiansen Ilse , Nilsson Göran , Celsing Fredrik , Sundström Gunnel , Luthman Mikaela , Tidefelt Ulf , Wallvik Jonas , Juliusson Gunnar
Published: March 2003

Summary.  A phase II study was undertaken to evaluate the efficacy and toxicity of a new schedule of cladribine administration (10 mg/m2 orally daily for 3 d every 3 weeks) in 107 patients with B‐cell chronic lymphocytic leukaemia (CLL). To minimize toxicity, treatment withdrawal criteria were defined. The results of the 63 previously untreated patients were retrospectively compared with 63 from an earlier study using a 5‐d monthly schedule. The compiled data were analysed for prognostic factors for survival. No significant difference regarding response were seen in the two cohorts of the 126 previously untreated patients. The complete response (CR), nodular partial response (nPR) and partial response (PR) rates were 15%, 21% and 41%. Quality of response had no impact on survival. The 3‐ and 5‐year overall survival for previously untreated patients was 73% and 58%, respectively, with a median follow‐up of 54 months. Pretreatment haemoglobin < 11·0 g/dl and elevated beta‐2‐microglobulin had a negative influence on survival. Major infections occurred in 21% of patients in the 3‐d study compared with 35% in the 5‐d study. The overall response (OR) and CR rates in the 40 previously treated patients were 34% and 5% respectively. Median overall survival was 24 months and median progression‐free survival for responding patients was 14 months. Cladribine used as a single agent is an effective treatment with an acceptable safety profile for pretreated and untreated B‐CLL. The achievement of complete remission was not a prerequisite for long‐term survival.
A novel immunocytochemical assay for the detection of serotonin in platelets
Authors: Maurer‐Spurej Elisabeth , Dyker Kate , Gahl William A. , Devine Dana V.
Published: March 2003

Summary. A method for the rapid, inexpensive and easy detection of platelet serotonin (5‐hydroxytryptamine, 5‐HT) is not currently available. Consequently, many patients suffering from unresolved platelet‐related bleeding disorders are not examined for a possible platelet 5‐HT deficiency. The direct measurement of 5‐HT concentration with high‐performance liquid chromatography (HPLC) or serotonin enzyme‐linked immunosorbent assay (ELISA) is costly and highly demanding. Indirect methods, which determine the content of ATP or calcium with lumi‐aggregometry or electron microscopy, rely upon the assumption that the ATP or calcium concentration is equivalent to that of 5‐HT. We have developed a fluorescence‐based assay for 5‐HT that can be performed within 2 h on fresh or frozen samples using a fluorescence microscope or a flow cytometer. The assay requires only 0·2 ml of platelet‐rich plasma and might therefore be of particular interest for paediatric patients. Samples from control and patient donors were analysed for 5‐HT with the new immunocytochemical assay in comparison with HPLC and/or 5‐HT ELISA. Patients with Hermansky–Pudlak syndrome were readily identified. The new assay was also reliable in cases where the 5‐HT content of dense granules was not correlated with the calcium or ATP content, such as in calcium deficiency or in the presence of selective serotonin reuptake inhibitors.
Chromosomal abnormalities in T‐cell large granular lymphocyte leukaemia: report of two cases and review of the literature
Authors: Wong K. F. , Chan J. C. W. , Liu H. S. Y. , Man C. , Kwong Y. L.
Published: March 2003

Summary. Cytogenetic information on T‐cell large granular lymphocyte leukaemia (T‐LGL; large granular lymphocytosis) is limited. We report two cases of T‐LGL with unusual karyotypic aberrations. The first case showed a novel inv(7)(p15q22) as the sole chromosomal abnormality, while the second case showed an inv(14)(q11q32) with evidence of clonal evolution. The breakpoints 7p14–p15 and 14q11 coincide with the T‐cell receptor (TCR)‐γ and TCR‐α/TCR‐δ gene loci respectively. This is the first report describing the possible involvement of T‐cell receptor genes in karyotypic aberrations in T‐LGL.
Plasma exchange as a source of protein C for acute onset protein C pathway failure
Authors: Hodgson Andy , Ryan Tom , Moriarty Jan , Mellotte George , Murphy Ciaran , Smith Owen P.
Published: March 2003

Summary.  Severe bacterial sepsis, particularly secondary to meningococcaemia, is a well‐recognized cause of purpura fulminans resulting from severe acquired protein C (PC) deficiency. Recently, PC and activated protein C (APC) concentrate replacement therapy has been shown to improve outcome in patients with meningococcaemia‐ associated purpura fulminans and severe sepsis respectively. Despite these impressive findings, PC and APC concentrates are not currently widely available. We describe a 31‐year‐old patient with pneumococcal septic shock, purpura fulminans (PF) and severe acquired PC deficiency, whom we successfully treated with conventional therapy and high‐volume plasma exchange as a source of PC.
High‐dose chlorambucil for the treatment of chronic lymphocytic leukaemia and low‐grade non‐Hodgkin's lymphoma
Authors: Summerfield Geoffrey P. , Taylor Penelope R. A. , Mounter Philip J. , Proctor Stephen J.
Published: March 2003

Summary. Chlorambucil has been used for many years for the treatment of low‐grade B‐cell lymphoproliferative disorders, including chronic lymphocytic leukaemia and low‐grade non‐Hodgkin's lymphoma. There is evidence in the literature that increasing the dose of chlorambucil produces better results than ‘standard’ doses in terms of response rates and overall survival. There is also evidence that this approach may be at least as effective as the use of fludarabine, as well as being very much less expensive. We describe a high‐dose chlorambucil (HDC) regimen, which involves a sustained but intermittent dose of chlorambucil, i.e. 30 mg/d for 4 d per week for 4 weeks, followed by a further four courses at fortnightly intervals for 8 weeks (a total of eight 4‐d courses) given as a single drug over an initial 12‐week period. The outcome of treatment in previously treated and untreated patients was excellent, with a median time to treatment failure of 33 months for the patient cohort overall and for previously treated and chemotherapy‐naive patients of 13 and 104 months respectively. In patients previously treated with fludarabine, 78% had a response. Autoimmune haemolytic anaemia was reversed in one patient. Toxicity, both haematological and other, was minimal. We propose that escalated‐dose chlorambucil regimens should be compared with fludarabine in randomized controlled trials, rather than ‘standard’ lower dose protocols.
Accelerated postoperative recovery programme after colonic resection improves physical performance, pulmonary function and body composition
Authors: Basse L , Raskov H H , Hjort Jakobsen D , Sonne E , Billesbølle P , Hendel H W , Rosenberg J , Kehlet H
Published: March 2003

Background

Postoperative organ dysfunction contributes to morbidity, hospital stay and convalescence. Multimodal rehabilitation with epidural analgesia, early oral feeding, mobilization and laxative use after colonic resection has reduced ileus and hospital stay.

Methods

Fourteen patients receiving conventional care (group 1) and 14 patients who had multimodal rehabilitation (group 2) were studied before and 8 days after colonic resection. Outcome measures included postoperative mobilization, body composition by whole-body dual X-ray absorptiometry, cardiovascular response to treadmill exercise, pulmonary function and nocturnal oxygen saturation.

Results

Defaecation occurred earlier (median day 1 versus day 4) and hospital stay was shorter (median 2 versus 12 days) in patients who had multimodal treatment. Lean body and fat mass decreased in group 1 but not in group 2. Exercise performance decreased by 44 per cent in group 1 but was unchanged in group 2. A postoperative increase in heart rate (HR) response to exercise was avoided in group 2. Pulmonary function decreased in group 1 but not in group 2. There was less nocturnal postoperative hypoxaemia in group 2. Cardiac demand–supply (HR/oxygen saturation ratio) increased in group 1 but not in group 2.

Conclusion

Multimodal rehabilitation prevents reduction in lean body mass, pulmonary function, oxygenation and cardiovascular response to exercise after colonic surgery.
Characterization and localization of human type10 17β‐hydroxysteroid dehydrogenase
Authors: He Xue‐Ying , Merz George , Yang Ying‐Zi , Mehta Penkaj , Schulz Horst , Yang Song‐Yu
Published: March 2003

The tissue distribution, subcellular localization, and metabolic functions of human 17β‐hydroxysteroid dehydrogenase type 10/short chain l‐3‐hydroxyacyl‐CoA dehydrogenase have been investigated. Human liver and gonads are abundant in this enzyme, but it is present in only negligible amounts in skeletal muscle. Its N‐terminal sequence is a mitochondrial targeting sequence, but is not required for directing this protein to mitochondria.  Immunocytochemical studies demonstrate that this protein, which has been referred to as ER‐associated amyloid β‐binding protein (ERAB), is not detectable in the ER of normal tissues. We have established that protocols employed to investigate the subcellular distribution of ERAB yield ER fractions rich in mitochondria. Mitochondria‐associated membrane fractions believed to be ER fractions were employed in ERAB/Aβ‐binding alcohol dehydrogenase studies. The present studies establish that in normal tissues this protein is located in mitochondria. This feature distinguishes it from all known 17β‐hydroxysteroid dehydrogenases, and endows mitochondria with the capability of modulating intracellular levels of the active forms of sex steroids.
The two myostatin genes of Atlantic salmon (Salmo salar) are expressed in a variety of tissues
Authors: Østbye Tone‐Kari , Galloway Trina Falck , Nielsen Christer , Gabestad Irene , Bardal Tora , Andersen Øivind
Published: March 2003

Two myostatin isoforms were identified in Atlantic salmon (Salmo salar) by RT‐PCR, and genomic sequences encoding this negative muscle growth factor were for the first time isolated from a nonmammalian species. Salmon myostatin isoform I is transcribed in white skeletal muscle as a 2346‐nucleotide mRNA species that encodes a precursor protein of 373 amino acids. Salmon myostatin I shows 93% sequence identity with isoform II which was isolated from white muscle as a partial cDNA sequence of 1409 nucleotides. In contrast to the restricted gene expression of myostatin in mammals, salmon myostatin I and II mRNAs were identified by RT‐PCR in multiple tissues, including white muscle, intestine, brain, gills, tongue and eye. In addition, isoform I mRNA was found in red skeletal muscle, heart, spleen, and ovarian tissue. Using polyclonal antibodies against both isoforms, a 55‐kDa precursor protein was detected by Western blot analysis in the red and white skeletal muscle, heart, intestine, and brain. Immunoreactive peptides of 35–40 kDa were identified in the gills, tongue, spleen, and head kidney, while the 25‐kDa mature myostatin was found in the eye and serum, and in vitro expressed in rabbit reticulocyte lysate. Salmon myostatin was immunohistochemically localized in the sarcoplasma of red and white muscle fibres, in intestinal epithelial cells, at the basis of the branchial primary lamellae, and in odontoblasts and ameloblasts of the tongue teeth. The results indicate that the role of fish myostatin may not be restricted to muscle growth regulation, but may have additional functions similar to the growth/differentiation factor‐11 in mammals.
Biotinylation of histones in human cells
Authors: Stanley J. Steven , Griffin Jacob B. , Zempleni Janos
Published: March 2003

An enzymatic mechanism has been proposed by which biotinidase may catalyze biotinylation of histones. Here, human cells were found to covalently bind biotin to histones H1, H2A, H2B, H3, and H4. Cells respond to proliferation with increased biotinylation of histones; biotinylation increases early in the cell cycle and remains increased during the cycle. Notwithstanding the catalytic role of biotinidase in biotinylation of histones, mRNA encoding biotinidase and biotinidase activity did not parallel the increased biotinylation of histones in proliferating cells. Biotinylation of histones might be regulated by enzymes other than biotinidase or by the rate of histone debiotinylation.
The Aspergillus nigerd‐xylulose kinase gene is co‐expressed with genes encoding arabinan degrading enzymes, and is essential for growth on d‐xylose and l‐arabinose
Authors: vanKuyk Patricia A. , de Groot Marco J. L. , Ruijter George J. G. , de Vries Ronald P. , Visser Jaap
Published: March 2003

The Aspergillus nigerd‐xylulose kinase encoding gene has been cloned by complementation of a strain deficient in d‐xylulose kinase activity. Expression of xkiA was observed in the presence of l‐arabinose, l‐arabitol and d‐xylose. Expression of xkiA is not mediated by XLNR, the xylose‐dependent positively‐acting xylanolytic regulator. Although the expression of xkiA is subject to carbon catabolite repression, the wide domain regulator CREA is not directly involved. The A. nigerd‐xylulose kinase was purified to homogeneity, and the molecular mass determined using electrospray ionization mass spectrometry agreed with the calculated molecular mass of 62816.6 Da. The activity of XKIA is highly specific for d‐xylulose. Kinetic parameters were determined as Km(d‐xylulose) = 0.76 mm and Km(ATP) = 0.061 mm. Increased transcript levels of the genes encoding arabinan and xylan degrading enzymes, observed in the xylulose kinase deficient strain, correlate with increased accumulation of l‐arabitol and xylitol, respectively. This result supports the suggestion that l‐arabitol may be the specific low molecular mass inducer of the genes involved in arabinan degradation. It also suggests a possible role for xylitol in the induction of xylanolytic genes. Conversely, overproduction of XKIA did not reduce the size of the intracellular arabitol and xylitol pools, and therefore had no effect on expression of genes encoding xylan and arabinan degrading enzymes nor on the activity of the enzymes of the catabolic pathway.
Screening of antifeedant activity in brain extracts led to the identification of sulfakinin as a satiety promoter in the German cockroach.
Authors: Maestro José L. , Aguilar Ruth , Pascual Nuria , Valero Mari‐Luz , Piulachs Maria‐Dolors , Andreu David , Navarro Isabel , Bellés Xavier
Published: March 2003

The feeding cycle of the adult female cockroach Blattella germanica parallels vitellogenesis. The study of the mechanisms that regulate this cycle led us to look for food‐intake inhibitors in brain extracts. The antifeedant activity of brain extracts was tested in vivo by injecting the extract and measuring the carotenoids contained in the gut from carrot ingested after the treatment. By HPLC fractionation and tracking the biological activity with the carrot test, we isolated the sulfakinin EQFDDY(SO3H) GHMRFamide (Pea‐SK). A synthetic version of the peptide inhibited food intake when injected at doses of 1 µg (50% inhibition) and 10 µg (60% inhibition). The sulfate group was required for food‐intake inhibition. These biological and structural features are similar to those of the gastrin–cholecystokinin (gastrin–CCK) family of vertebrate peptides. However, heterologous feeding assays (human CCK‐8 tested on B. germanica, and Pea‐SK tested on the goldfish Carassius auratus) were negative. In spite of this, alignment and cluster analysis of these and other structurally similar peptide families suggest that sulfakinins and gastrin–CCKs are homologous, and that mechanisms of feeding regulation involving these regulatory peptides may have been conserved during evolution between insects and vertebrates.
Behaviour of bovine phosphatidylethanolamine‐binding protein with model membranes.
Authors: Vallée Béatrice S. , Tauc Patrick , Brochon Jean‐Claude , Maget‐Dana Régine , Lelièvre Dominique , Metz‐Boutigue Marie‐Hélène , Bureaud Nicole , Schoentgen Françoise
Published: March 2003

The ability of phosphatidylethanolamine‐binding protein (PEBP) to bind membranes was tested by using small and large unilamellar vesicles and monolayers composed of l‐α‐1,2‐dimyristoylphosphatidylcholine, l‐α‐1,2‐dimyristoylphosphatidylglycerol and l‐α‐1,2‐dimyristoylphosphatidylethanolamine. PEBP only bound to model membranes containing l‐α‐1,2‐dimyristoylphosphatidylglycerol; the interaction was primarily due to electrostatic forces between the basic protein and the acidic phospholipids. Further experiments indicated that the interaction was not dependent on the length and unsaturation of the phospholipid acyl chains and was not modified by the presence of cholesterol in the membrane. PEBP affinity for negatively charged membranes is puzzling considering the previous identification of the protein as a phosphatidylethanolamine‐binding protein, and suggests that the association of PEBP with phospholipid membranes is driven by a mechanism other than its binding to solubilized phosphatidylethanolamine. An explanation was suggested by its three‐dimensional structure: a small cavity at the protein surface has been reported to be the binding site of the polar head of phosphatidylethanolamine, while the N‐terminal and C‐terminal parts of PEBP, exposed at the protein surface, appear to be involved in the interaction with membranes. To test this hypothesis, we synthesized the two PEBP terminal regions and tested them with model membranes in parallel with the whole protein. Both peptides displayed the same behaviour as whole PEBP, indicating that they could participate in the binding of PEBP to membranes. Our results strongly suggest that PEBP directly interacts with negatively charged membrane microdomains in living cells.
Isolation, enzymatic properties, and mode of action of an  exo‐1,3‐β‐glucanase from T. viride
Authors: Kulminskaya Anna A. , Thomsen Karl K. , Shabalin Konstantin A. , Sidorenko Irina A. , Eneyskaya Elena V. , Savel'Ev Andrew N. , Neustroev Kirill N.
Published: March 2003

An exo‐1,3‐β‐glucanase has been isolated from cultural filtrate of T. viride AZ36. The N‐terminal sequence of the purified enzyme (m = 61 ± 1 kDa) showed no significant homology to other known glucanases. The 1,3‐β‐glucanase displayed high activity against laminarins, curdlan, and 1,3‐β‐oligoglucosides, but acted slowly on 1,3‐1,4‐β‐oligoglucosides. No significant activity was detected against high molecular mass 1,3‐1,4‐β‐glucans. The enzyme carried out hydrolysis with inversion of the anomeric configuration. Whereas only glucose was released from the nonreducing terminus during hydrolysis of 1,3‐β‐oligoglucosides, transient accumulation of gentiobiose was observed during hydrolysis of laminarins. The gentiobiose was subsequently degraded to glucose. The Michaelis constants Km and Vmax have been determined for the hydrolysis of 1,3‐β‐oligoglucosides with degrees of polymerization ranging from 2 to 6. Based on these data, binding affinities for subsites were calculated. Substrate binding site contained at least five binding sites for sugar residues.
Information transfer in metabolic pathways
Authors: Cornish‐Bowden Athel , Cárdenas María Luz
Published: March 2003

Various metabolic models have been studied by computer simulation in an effort to understand why allowing for the reversibility of the reaction catalysed by pyruvate kinase, normally considered as irreversible for all practical purposes, significantly altered the behaviour of the model of glycolysis in Trypanosoma brucei[Eisenthal, R. & Cornish‐Bowden, A. (1998) J. Biol. Chem.273, 5500–5505]. Studies of several much simpler models indicate that the enzymes catalysing early steps in a pathway must receive information about the concentrations of the metabolites at the end of the pathway if a model is to be able to reach a steady state; treating all internal steps as reversible is just one way of ensuring this. Feedback inhibition provides a much better way, and as long as feedback loops are present in a model it makes almost no difference to the behaviour whether the intermediate steps with large equilibrium constants are treated as irreversible. In the absence of feedback loops, ordinary product inhibition of all the enzymes in the chain can also transfer information; this is efficient for regulating fluxes but very inefficient for regulating intermediate concentrations. More complicated patterns of regulation, such as activation of a competing branch or forcing flux through a parallel route, can also serve to some degree as ways of passing information around an irreversible step. However, they normally do so less efficiently than inhibition, because the extent to which an enzyme or a pathway can be activated always has an upper limit (which may be below what is required), whereas most enzymes are inhibited completely at saturating concentrations of inhibitor.
Inhibition of nuclear pre‐mRNA splicing by antibiotics in vitro
Authors: Hertweck Maren , Hiller Reinhard , Mueller Manfred W.
Published: March 2003

A number of antibiotics have been reported to disturb the decoding process in prokaryotic translation and to inhibit the function of various natural ribozymes. We investigated the effect of several antibiotics on in vitro splicing of a eukaryotic nuclear pre‐mRNA (β‐globin). Of the eight antibiotics studied, erythromycin, Cl‐tetracycline and streptomycin were identified as splicing inhibitors in nuclear HeLa cell extract. The Ki values were 160, 180 and 230 µm, respectively. Cl‐tetracycline‐mediated and streptomycin‐mediated splicing inhibition were in the molar inhibition range for hammerhead and human hepatitis delta virus ribozyme self‐cleavage (tetracycline), of group‐I intron self‐splicing (streptomycin) and inhibition of RNase P cleavage by some aminoglycosides. Cl‐tetracycline and the aminocyclitol glycoside streptomycin were found to have an indirect effect on splicing by unspecific binding to the pre‐mRNA, suggesting that the inhibition is the result of disturbance of the correct folding of the pre‐mRNA into the splicing‐compatible tertiary structure by the charged groups of these antibiotics. The macrolide, erythromycin, the strongest inhibitor, had only a slight effect on formation of the presplicing complexes A and B, but almost completely inhibited formation of the splicing‐active C complex by binding to nuclear extract component(s). This results in direct inhibition of the second step of pre‐mRNA splicing. To our knowledge, this is the first report on specific inhibition of nuclear splicing by an antibiotic. The functional groups involved in the interaction of erythromycin with snRNAs and/or splicing factors require further investigation.
The plant S‐adenosyl‐l‐methionine:Mg‐protoporphyrin IX methyltransferase is located in both envelope and thylakoid chloroplast membranes
Authors: Block Maryse A. , Tewari Arun Kumar , Albrieux Catherine , Maréchal Eric , Joyard Jacques
Published: March 2003

Chlorophyll biosynthesis requires a metabolic dialog between the chloroplast envelope and thylakoids where biosynthetic activities are localized. Here, we report the first plant S‐adenosyl‐l‐methionine:Mg‐protoporphyrin IX methyltransferase (MgPIXMT) sequence identified in the Arabidopsis genome owing to its similarity with the Synechocystis sp. MgPIXMT gene. After expression in Escherichia coli, the recombinant Arabidopsis thaliana cDNA was shown to encode a protein having MgPIXMT activity. The full‐length polypeptide exhibits a chloroplast transit peptide that is processed during import into the chloroplast. The mature protein contains two functional regions. The C‐terminal part aligns with the Synechocystis full‐length protein. The corresponding truncated region binds to Ado‐met, as assayed by UV crosslinking, and is shown to harbor the MgPIXMT activity. Downstream of the cleaved transit peptide, the 40 N‐terminal amino acids of the mature protein are very hydrophobic and enhance the association of the protein with the membrane. In A. thaliana and spinach, the MgPIXMT protein has a dual localization in chloroplast envelope membranes as well as in thylakoids. The protein is active in each membrane and has the same apparent size corresponding to the processed mature protein. The protein is very likely a monotopic membrane protein embedded within one leaflet of the membrane as indicated by ionic and alkaline extraction of each membrane. The rationale for a dual localization of the protein in the chloroplast is discussed.
What does it mean to be natively unfolded?
Authors: Uversky Vladimir N.
Published: March 2003

Natively unfolded or intrinsically unstructured proteins constitute a unique group of the protein kingdom. The evolutionary persistence of such proteins represents strong evidence in the favor of their importance and raises intriguing questions about the role of protein disorders in biological processes. Additionally, natively unfolded proteins, with their lack of ordered structure, represent attractive targets for the biophysical studies of the unfolded polypeptide chain under physiological conditions in vitro. The goal of this study was to summarize the structural information on natively unfolded proteins in order to evaluate their major conformational characteristics. It appeared that natively unfolded proteins are characterized by low overall hydrophobicity and large net charge. They possess hydrodynamic properties typical of random coils in poor solvent, or premolten globule conformation. These proteins show a low level of ordered secondary structure and no tightly packed core. They are very flexible, but may adopt relatively rigid conformations in the presence of natural ligands. Finally, in comparison with the globular proteins, natively unfolded polypeptides possess ‘turn out’ responses to changes in the environment, as their structural complexities increase at high temperature or at extreme pH.
Disulfide bond formation through Cys186 facilitates functionally relevant dimerization of trimeric hyaluronan‐binding protein 1 (HABP1)/p32/gC1qR
Authors: Jha Babal Kant , Salunke Dinakar M. , Datta Kasturi
Published: March 2003

Hyaluronan‐binding protein 1 (HABP1), a ubiquitous multifunctional protein, interacts with hyaluronan, globular head of complement component 1q (gC1q), and clustered mannose and has been shown to be involved in cell signalling. In vitro, this recombinant protein isolated from human fibroblast exists in different oligomeric forms, as is evident from the results of various independent techniques in near‐physiological conditions. As shown by size‐exclusion chromatography under various conditions and glutaraldehyde cross‐linking, HABP1 exists as a noncovalently associated trimer in equilibrium with a small fraction of a covalently linked dimer of trimers, i.e. a hexamer. The formation of a covalently‐linked hexamer of HABP1 through Cys186 as a dimer of trimers is achieved by thiol group oxidation, which can be blocked by modification of Cys186. The gradual structural transition caused by cysteine‐mediated disulfide linkage is evident as the fluorescence intensity increases with increasing Hg2+ concentration until all the HABP1 trimer is converted into hexamer. In order to understand the functional implication of these transitions, we examined the affinity of the hexamer for different ligands. The hexamer shows enhanced affinity for hyaluronan, gC1q, and mannosylated BSA compared with the trimeric form. Our data, analyzed with reference to the HABP1/p32 crystal structure, suggest that the oligomerization state and the compactness of its structure are factors that regulate its function.
Structural and serological relatedness of the O‐antigensof Proteus penneri 1 and 4 from a novel Proteus serogroup O72
Authors: Sidorczyk Zygmunt , Toukach Filip V. , Zych Krystyna , Drzewiecka Dominika , Arbatsky Nikolay P. , Shashkov Alexander S. , Knirel Yuriy A.
Published: March 2003

O‐specific polysaccharides (O‐antigens) of the lipopolysaccharides (LPS) of Proteus penneri strains 1 and 4 were studied using sugar analysis, 1H and 13C NMR␣spectroscopy, including 2D COSY, H‐detected 1H,13C␣HMQC, and rotating‐frame NOE spectroscopy (ROESY). The following structures of the tetrasaccharide (strain 1) and pentasaccharide (strain 4) repeating units of the polysaccharides were established:

In the polysaccharide of P. penneri strain 4, glycosylation with the lateral Glc residue (75%) and O‐acetylation of the lateral GalNAc residue (55%) are nonstoichiometric. This polysaccharide contains also other, minor O‐acetyl groups, whose positions were not determined.

The structural similarity of the O‐specific polysaccharides was consistent with the close serological relatedness of the LPS, which was demonstrated by immunochemical studies with O‐antisera against P. penneri 1 and 4. Based on these data, it was proposed to classify P. penneri strains 1 and 4 into a new Proteus serogroup, O72, as two subgroups, O72a and O72a,b, respectively. Serological cross‐reactivity of P. penneri 1 O‐antiserum with the LPS of P. penneri 40 and 41 was substantiated by the presence of an epitope(s) on the LPS core region shared by all P. penneri strains studied.
Fluorescence study of the high pressure‐induced denaturation of skeletal muscle actin
Authors: Ikeuchi Yoshihide , Suzuki Atsusi , Oota Takayoshi , Hagiwara Kazuaki , Tatsumi Ryuichi , Ito Tatsumi , Balny Claude
Published: March 2003

Ikkai & Ooi [Ikkai, T. & Ooi, T. (1966) Biochemistry5, 1551–1560] made a thorough study of the effect of pressure on G‐␣and F‐actins. However, all of the measurements in their study were made after the release of pressure. In the present experiment in situ observations were attempted by using εATP to obtain further detailed kinetic and thermodynamic information about the behaviour of actin under pressure. The dissociation rate constants of nucleotides from actin molecules (the decay curve of the intensity of fluorescence of εATP‐G‐actin or εADP–F‐actin) followed first‐order kinetics. The volume changes for the denaturation of G‐actin and F‐actin were estimated to be −72 mL·mol−1 and −67 mL·mol−1 in the presence of ATP, respectively. Changes in the intensity of fluorescence of F‐actin whilst under pressure suggested that εADP–F‐actin was initially depolymerized to εADP–G‐actin; subsequently there was quick exchange of the εADP for free εATP, and then polymerization occurred again with the liberation of phosphate from εATP bound to G‐actin in the presence of excess ATP. In the higher pressure range (> 250 MPa), the partial collapse of the three‐dimensional structure of actin, which had been depolymerized under pressure, proceeded immediately after release of the nucleotide, so that it lost the ability to exchange bound ADP with external free ATP and so was denatured irreversibly. An experiment monitoring εATP fluorescence also demonstrated that, in the absence of Mg2+‐ATP, the dissociation of actin‐heavy meromyosin (HMM) complex into actin and HMM did not occur under high pressure.
Human bile salt‐stimulated lipase has a high frequency of size variation due to a hypervariable region in exon 11
Authors: Lindquist Susanne , Bläckberg Lars , Hernell Olle
Published: March 2003

The apparent molecular mass of human milk bile salt‐stimulated lipase (BSSL) varies between mothers. The molecular basis for this is unknown, but indirect evidence has suggested the differences to reside in a region of repeats located in the C‐terminal part of the protein. We here report that a polymorphism within exon 11 of the BSSL gene is the explanation for the molecular variants of BSSL found in milk. By Southern blot hybridization we analyzed the BSSL gene from mothers known to have BSSL of different molecular masses in their milk. A␣polymorphism was found within exon 11, previously shown to consist of 16 near identical repeats of 33 bp each. We detected deletions or, in one case, an insertion␣corresponding to the variation in molecular mass of the BSSL protein found in milk from the respective woman. Furthermore, we found that 56%, out of 295 individuals studied, carry deletions or insertions within exon 11 in one or both alleles of the BSSL gene. Hence, this is a hypervariable region and the current understanding that exon 11 in the human BSSL gene encodes 16 repeats is an oversimplification and needs to be revisited. Natural variation in the molecular mass of BSSL may have clinical implications.
Ductus ejaculatorius peptide 99B (DUP99B), a novel Drosophila melanogaster sex‐peptide pheromone
Authors: Saudan Philippe , Hauck Klaus , Soller Matthias , Choffat Yves , Ottiger Michael , Spörri Michael , Ding Zhaobing , Hess Daniel , Gehrig Peter M , Klauser Stefan , Hunziker Peter , Kubli Eric
Published: March 2003

We have characterized a glycosylated, 31 amino‐acid peptide of 4932 Da isolated from Drosophila melanogaster males. The mature peptide contains a sugar moiety of 1184 Da at a NDT consensus glycosylation site and a disulfide bond. It is synthesized in the male ejaculatory duct via a 54 amino‐acid precursor containing an N‐terminal signal peptide and Arg‐Lys at the C‐terminus which is cleaved off during maturation. The gene contains an intron of 53 bp and is localized in the cytological region 99B of the D. melanogaster genome. The peptide is therefore named DUP99B (for ductus ejaculatorius peptide, cytological localization 99B). The C‐terminal parts of mature DUP99B and D. melanogaster sex‐peptide (ACP70A) are highly homologous. Injected into virgin females, DUP99B elicits the same postmating responses as sex‐peptide (increased oviposition, reduced receptivity). These effects are also induced by de‐glycosylated native peptide or synthetic DUP99B lacking the sugar moiety. Presence of the glycosyl group, however, decreases the amount needed to elicit the postmating responses. Homologies in the coding regions of the two exons of DUP99B and sex‐peptide, respectively, suggest that the two genes have evolved by gene duplication. Thus, we consider these two genes to be members of the new sex‐peptide gene family.
Interaction of the anterior fat body protein with the hexamerin receptor in the blowfly Calliphora vicina
Authors: Hansen Immo A. , Meyer Susanne R. , Schäfer Ingo , Scheller Klaus
Published: March 2003

In late larvae of the blowfly, Calliphora vicina, arylphorin and LSP‐2 proteins, which belong to the class of hexamerins, are selectively taken up by the fat body from the haemolymph. Hexamerin endocytosis is mediated by a specific membrane‐bound receptor, the arylphorin‐binding protein (ABP). Using the two‐hybrid technique, we found that the anterior fat body protein (AFP) interacts with the hexamerin␣receptor. AFP, a homologue of the mammalian calcium‐binding liver protein regucalcin (senescence marker protein‐30), exhibits a strong binding affinity for a naturally occurring C‐terminal cleavage fragment of the hexamerin receptor precursor (the P30 peptide) and other receptor cleavage products that contain P30. Expression of AFP mRNA and protein is restricted to the anterior part of the fat body tissue and to haemocytes in last‐instar larvae. AFP mRNA occurs in all postembryonic developmental stages. Our results suggest that AFP plays a role in the regulation of hexamerin uptake by fat body cells along the anterior–posterior axis.
Characterization of a partially folded intermediate of stem bromelain at low pH
Authors: Haq Soghra Khatun , Rasheedi Sheeba , Khan Rizwan Hasan
Published: March 2003

Equilibrium studies on the acid included denaturation of stem bromelain (EC 3.4.22.32) were performed by CD spectroscopy, fluorescence emission spectroscopy and binding of the hydrophobic dye, 1‐anilino 8‐naphthalene sulfonic acid (ANS). At pH 2.0, stem bromelain lacks a well defined tertiary structure as seen by fluorescence and near‐UV CD spectra. Far‐UV CD spectra show retention of some native like secondary structure at pH 2.0. The mean residue ellipticities at 208 nm plotted against pH showed a transition around pH 4.5 with loss of secondary structure leading to the formation of an acid‐unfolded state. With further decrease in pH, this unfolded state regains most of its secondary structure. At pH 2.0, stem bromelain exists as a partially folded intermediate containing about 42.2% of the native state secondary structure Enhanced binding of ANS was observed in this state compared to the native folded state at neutral pH or completely unfolded state in the presence of 6 m GdnHCl indicating the exposure of hydrophobic regions on the protein molecule. Acrylamide quenching of the intrinsic tryptophan residues in the protein molecule showed that at pH 2.0 the protein is in an unfolded conformation with more tryptophan residues exposed to the solvent as compared to the native conformation at neutral pH. Interestingly, stem bromelain at pH 0.8 exhibits some characteristics of a molten globule, such as an enhanced ability to bind the fluorescent probe as well as considerable retention of secondary structure. All the above data taken together suggest the existence of a partially folded intermediate state under low pH conditions.
New polymorphisms of haematopoietic prostaglandin D synthase and human prostanoid DP receptor genes
Authors: Noguchi E. , Shibasaki M. , Kamioka M. , Yokouchi Y. , Yamakawa‐Kobayashi K. , Hamaguchi H. , Matsui A. , Arinami T.
Published: March 2003

Background Prostaglandin D2 (PGD2), a major cyclo‐oxygenase metabolite of arachidonic acid in mast cells, induces bronchoconstriction in the human lung. It has been reported that mice lacking PGD receptor fail to develop the bronchial hyper‐responsiveness upon ovalbumin challenge, suggesting that PGD2 functions as a mediator of allergic asthma.

Objective To determine if there are any mutations associated with the development of asthma in the haematopoietic prostaglandin D synthase (H‐PGDS) gene and the human prostanoid DP receptor (PTGDR) gene.

Methods and results We screened the 5′flanking and coding regions of the H‐PGDS gene and the PTGDR gene by direct sequence. We identified one variant in intron 2 (IVS2 + 11 A > C) and one variant in intron 3 (IVS3 + 13T > C) of the H‐PGDS gene, and two variants in the 5′flanking region of the PTGDR gene (−197T > C and −2C > T). The IVS3 + 13T > C and −197T > C variants were rare, appearing only once in 48 subjects. transmission disequilibrium test (TDT) analysis of 144 asthmatic families revealed that the IVS2 + 11 A allele of the H‐PGDS gene was significantly transmitted preferentially to asthma‐affected children (P = 0.0056), but no association was observed between −2C/T polymorphism of the PTGDR gene and asthma (P > 0.05).

Conclusion Our results suggest that the IVS2 + 11 A/C allele may be involved in the development of asthma in the Japanese population.
Low survival rate and high predation in the African hingeback tortoiseKinixys spekii
Authors: Coulson (deceased) Ian M. , Hailey Adrian
Published: March 2003

Live and deadKinixys spekiiwere collected in the Sengwa Wildlife Research Area, Zimbabwe over a 12‐year period. Live tortoises were sexable at a midline plastron length of 100 mm; females were considered sexually mature at 140 mm (reached by age 9 years) and males at 120 mm (at age 7 years). Adult females were significantly larger than males, on average by 14 mm in length and by 1.43 times in mass. Mark–recapture analysis in a 2 km2area showed a population density of sexable tortoises of 0.16 ha−1. The survival rate was estimated by recaptures, by the frequency distribution of age at death, and by the mean age of live tortoises, and averaged 0.74 year−1. Seventy‐seven to 89% of dead tortoises showed evidence of predation, depending on the criteria used. Damage occurred in characteristic forms, loss of the front or rear of the plastron, or holes in the carapace and plastron, which were attributed to predation by mammals and ground hornbills, respectively.K. spekiihad similar body size and sexual size dimorphism to Mediterranean tortoises (Testudo), but population density was much lower and the mortality rate was twice as high, probably due to the abundant African predators. High mortality was offset by a rate of juvenile growth twice that ofTestudo.
Fire frequency and species associations in perennial grasslands of south‐west Ethiopia
Authors: Jacobs Michael J. , Schloeder Catherine A.
Published: March 2003

Fires play an important role in shaping species composition and associations in East African grasslands. Grassland plains of Omo National Park (ONP), Ethiopia, which are dominated by perennial grass species, exist in a fire‐prone environment. Our objective was to determine if the current pattern of plant species composition in ONP's grassland plains was correlated with the historical pattern of fire frequency. Species composition was determined at 160 plots along 30 west‐trending transects, approximately 2 km apart. Fire frequency for each plot was estimated using eleven Landsat satellite images that spanned a 23‐year period. The Mantel and partial Mantel tests were used to test for correlation between species composition and fire frequency.

Plots in the northern grassland plain appear to burn every other year, while plots in the southern grassland plain burn once every 4–5 years. However, no significant correlation was found between patterns in species composition and fire frequency. Likewise, a selective analysis by functional group (i.e. grass, shrubs) revealed no relationship with fire frequency. It appears that fire does play a role in dictating species composition in ONP, but only in the sense that species that can tolerate the current fire regime persist. Species distribution, however, appears to be under the influence of other factors.
Feature
Authors: Waltham Tony
Published: March 2003

Migrating sand dunes are on the move today, but the Egyptian oases also contain landforms left from a wetter past.
Linking above‐ and below‐ground biodiversity: abundance and trophic complexity in soil as a response to experimental plant communities on abandoned arable land
Authors: Korthals G. W. , Smilauer P. , Van Dijk C. , Van Der Putten W. H.
Published: March 2003

This study investigates the effects of experimental plant communities on different trophic levels in the soil food web of abandoned arable land.

In April 1996, a biodiversity experiment commenced using a continuation of agricultural crop rotation (CCR), spontaneous succession with naturally colonizing plant species (NC) and late‐successional plant species sown in low‐diversity (LD, four plant species) and high‐diversity (HD, 15 plant species) communities. The nematode community was used as an indicator of the influence of the experimental plant communities on different trophic levels in the soil food web.

The nematode abundance in the experimental plant communities differed from that of the continued crop rotation, but there were hardly any differences between the natural, the low‐diversity and the high‐diversity plant communities.

The abundant plant‐feeding nematodes and the somewhat less abundant bacterivorous nematodes were stimulated most by the sowing treatments. Fungivorous nematodes were stimulated less, while the numbers of omnivorous and carnivorous nematodes did not change significantly.

The diversity of the nematode community did not change over 2 years.

It is concluded that experimental plant communities have either small short‐term effects or a delayed impact on the soil food web compared with the effect they have on above‐ground invertebrate community development.
Thermal performance of juvenile Atlantic Salmon,Salmo salarL.
Authors: JONSSON B. , FORSETH T. , JENSEN A. J. , NÆSJE T. F.
Published: March 2003

Experimental data for maximum growth and food consumption of Atlantic Salmon (Salmo salarL.) parr from five Norwegian rivers situated between 59 and 70°N were analysed and modelled. The growth and feeding models were also applied to groups of Atlantic Salmon growing and feeding at rates below the maximum. The data were fitted to the Ratkowsky model, originally developed for bacterial growth.

 The rates of growth and food consumption varied significantly among populations but the variation appeared unrelated to thermal conditions in the river of population origins. No correlation was found between the thermal conditions and limits for growth, thermal growth optima or maximum growth, and hypotheses of population‐specific thermal adaptation were not supported. Estimated optimum temperatures for growth were between 16 and 20 °C.

  Model parameter estimates differed among growth‐groups in that maximum growth and the performance breadth decreased from fast to slow growing individuals. The optimum temperature for growth did not change with growth rate.

  The model for food consumption (expressed in energy terms) peaked at 19–21 °C, which is only slightly higher than the optimal temperature for growth. Growth appeared directly related to food consumption. Consumption was initiated ≈2 °C below the lower temperature for growth and terminated ≈1·5 °C above the upper critical temperature for growth. Model parameter estimates for consumption differed among growth‐groups in a manner similar to the growth models.

 By combining the growth and consumption models, growth efficiencies were estimated. The maximum efficiencies were high, 42–58%, and higher in rivers offering hostile than benign feeding and growth opportunities.
Interactions of body shape, body size and stroke‐acceleration patterns in costs of underwater swimming by birds
Authors: Lovvorn J. R. , Liggins G. A.
Published: March 2003

For birds, mammals and turtles, costs of swimming by foot propulsion are usually much higher than for propulsion by wings or foreflippers. The propulsive efficiency with which limbs impart thrust to the water is greater for lift‐based wings than for drag‐based feet, but different acceleration patterns during oscillatory strokes may also alter total drag on the body fuselage (head and trunk).

 Because wing propulsion allows thrust on both upstroke and downstroke, whereas foot propulsion in many species (perhaps excepting grebes) has little or no thrust on the upstroke, foot propulsion requires higher speeds during a smaller fraction of the stroke to maintain the same mean speed. Because drag increases non‐linearly with increasing speed, higher instantaneous speeds in drag‐based foot propulsion may cause greater total drag on the body fuselage.

 Tow‐tank measurements have shown that foot‐propelled birds that swim with long necks extended have lower fuselage drag at high speeds than do wing‐propelled birds that swim with necks retracted. This difference might reduce the higher costs of drag‐based foot propulsion, but such effects must be evaluated in the context of drag at a range of speeds throughout oscillatory strokes.

 In quasi‐steady models of horizontal swimming underwater, stroke‐acceleration curves for both foot and wing propulsion were applied to a range of bird shapes and sizes. Higher fuselage drag during foot propulsion increased mechanical costs of transport (MCOT, J kg−1 m−1) by 26–40% in various species. Thus, a large fraction of the different costs of wing and foot propulsion might be explained in terms of drag on the body fuselage, independently of the propulsive efficiency of stroking limbs.

 When drag curves for different body shapes were combined with different oscillatory stroking patterns, swimming with a long neck extended did not reduce the higher total drag associated with drag‐based foot propulsion. Thus, although size and shape can affect drag measured at different constant speeds, effects of drag on locomotor costs depend much more on stroke‐acceleration patterns of different swimming modes.