bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhanced Display of Lipase on the
Escherichia coli
Cell Surface, Based on Transcriptome Analysis
Authors: Baek Jong Hwan , Han Mee-Jung , Lee Seung Hwan , Lee Sang Yup
Published: December 2009

A cell surface display system was developed using
Escherichia coli
OmpC as an anchoring motif. The fused
Pseudomonas fluorescens
SIK W1 lipase was successfully displayed on the surface of
E. coli
cells, and the lipase activity could be enhanced by the coexpression of the
gadBC
genes identified by transcriptome analysis.
A Putative P-Type ATPase, Apt1, Is Involved in Stress Tolerance and Virulence in
Cryptococcus neoformans
Authors: Hu Guanggan , Kronstad James W.
Published: December 2009

The export of virulence factors, such as the capsule polysaccharide, to the cell surface is a critical aspect of the pathogenicity of
Cryptococcus neoformans.
A view of capsule export via exocytosis and extracellular vesicles is emerging, but the molecular mechanisms underlying virulence factor transport pathways remain to be established. In this study, we characterized the
APT1
gene, which encodes a predicted integral membrane P-type ATPase belonging to the type IV, Drs2 family of aminophospholipid translocases (flippases) (APTs). APTs maintain the phospholipid asymmetry that is critical in membrane fusion events for trafficking and in establishing cell polarity. Deletion of the
APT1
gene resulted in phenotypes consistent with similar roles in
C. neoformans
. These included altered actin distribution, increased sensitivity to stress conditions (oxidative and nitrosative stress) and to trafficking inhibitors, such as brefeldin A and monensin, a reduction in exported acid phosphatase activity, and hypersensitivity to the antifungal drugs amphotericin B, fluconazole, and cinnamycin. However, there was no difference in growth, capsule size, or melanin production between the wild type and the
apt1
mutant strains at either 30°C or 37°C. Despite the absence of an influence on these major virulence factors, Apt1 was required for survival during interactions with macrophages, and
apt1
mutants exhibited attenuated virulence in a mouse inhalation model of cryptococcosis. Therefore, Apt1 contributes to virulence and the stress response in
C. neoformans
through apparent functions in membrane fusion and trafficking that do not influence the deposition of major virulence factors, such as capsule and melanin, outside the cell.
Synthetic β-(1→6)-Linked N-Acetylated and Nonacetylated Oligoglucosamines Used To Produce Conjugate Vaccines for Bacterial Pathogens
Authors: Gening Marina L. , Maira-Litrán Tomás , Kropec Andrea , Skurnik David , Grout Martha , Tsvetkov Yury E. , Nifantiev Nikolay E. , Pier Gerald B.
Published: December 2009

Vaccines for pathogens usually target strain-specific surface antigens or toxins, and rarely is there broad antigenic specificity extending across multiple species. Protective antibodies for bacteria are usually specific for surface or capsular antigens. β-(1→6)-Poly-
N
-acetyl-
d
-glucosamine (PNAG) is a surface polysaccharide produced by many pathogens, including
Staphylococcus aureus
,
Escherichia coli
,
Yersinia pestis
,
Bordetella pertussis
,
Acinetobacter baumannii
, and others. Protective antibodies to PNAG are elicited when a deacetylated glycoform (deacetylated PNAG [dPNAG]; <30% acetate) is used in conjugate vaccines, whereas highly acetylated PNAG does not induce such antibodies. Chemical derivation of dPNAG from native PNAG is imprecise, so we synthesized both β-(1→6)-
d
-glucosamine (GlcNH
2
) and β-(1→6)-
d
-
N
-acetylglucosamine (GlcNAc) oligosaccharides with linkers on the reducing termini that could be activated to produce sulfhydryl groups for conjugation to bromoacetyl groups introduced onto carrier proteins. Synthetic 5-mer GlcNH
2
(5GlcNH
2
) or 9GlcNH
2
conjugated to tetanus toxoid (TT) elicited mouse antibodies that mediated opsonic killing of multiple
S. aureus
strains, while the antibodies that were produced in response to 5GlcNAc- or 9GlcNAc-TT did not mediate opsonic killing. Rabbit antibodies to 9GlcNH
2
-TT bound to PNAG and dPNAG antigens, mediated killing of
S. aureus
and
E. coli
, and protected against
S. aureus
skin abscesses and lethal
E. coli
peritonitis. Chemical synthesis of a series of oligoglucosamine ligands with defined differences in N acetylation allowed us to identify a conjugate vaccine formulation that generated protective immune responses to two of the most challenging bacterial pathogens. This vaccine could potentially be used to engender protective immunity to the broad range of pathogens that produce surface PNAG.
The
Mycobacterium tuberculosis
High-Affinity Iron Importer, IrtA, Contains an FAD-Binding Domain
Authors: Ryndak Michelle B. , Wang Shuishu , Smith Issar , Rodriguez G. Marcela
Published: December 2009

Iron is an essential nutrient not freely available to microorganisms infecting mammals. To overcome iron deficiency, bacteria have evolved various strategies including the synthesis and secretion of high-affinity iron chelators known as siderophores. The siderophores produced and secreted by
Mycobacterium tuberculosis
, exomycobactins, compete for iron with host iron-binding proteins and, together with the iron-regulated ABC transporter IrtAB, are required for the survival of
M. tuberculosis
in iron deficient conditions and for normal replication in macrophages and in mice. This study further characterizes the role of IrtAB in
M. tuberculosis
iron acquisition. Our results demonstrate a role for IrtAB in iron import and show that the amino terminus domain of IrtA is a flavin-adenine dinucleotide-binding domain essential for iron acquisition. These results suggest a model in which the amino terminus of IrtA functions to couple iron transport and assimilation.
Genetic Basis for
Rhizobium etli
CE3 O-Antigen O-Methylated Residues That Vary According to Growth Conditions
Authors: Ojeda Kristylea J. , Box Jodie M. , Noel K. Dale
Published: December 2009

The
Rhizobium etli
CE3 O antigen is a fixed-length heteropolymer with O methylation being the predominant type of sugar modification. There are two O-methylated residues that occur, on average, once per complete O antigen: a multiply O-methylated terminal fucose and 2-O methylation of a fucose residue within a repeating unit. The amount of the methylated terminal fucose decreases and the amount of 2-
O
-methylfucose increases when bacteria are grown in the presence of the host plant,
Phaseolus vulgaris
, or its seed exudates. Insertion mutagenesis was used to identify open reading frames required for the presence of these O-methylated residues. The presence of the methylated terminal fucose required genes
wreA
,
wreB
,
wreC
,
wreD
, and
wreF
, whereas 2-O methylation of internal fucoses required the methyltransferase domain of bifunctional gene
wreM
. Mutants lacking only the methylated terminal fucose, lacking only 2-O methylation, or lacking both the methylated terminal fucose and 2-O methylation exhibited no other lipopolysaccharide structural defects. Thus, neither of these decorations is required for normal O-antigen length, transport, or assembly into the final lipopolysaccharide. This is in contrast to certain enteric bacteria in which the absence of a terminal decoration severely affects O-antigen length and transport.
R. etli
mutants lacking only the methylated terminal fucose were not altered in symbiosis with host
Phaseolus vulgaris
, whereas mutants lacking only 2-
O
-methylfucose exhibited a delay in nodule development during symbiosis. These results support previous conclusions that the methylated terminal fucose is dispensable for symbiosis, whereas 2-O methylation of internal fucoses somehow facilitates early events in symbiosis.
Genome Sequence of a Recently Emerged, Highly Transmissible, Multi-Antibiotic- and Antiseptic-Resistant Variant of Methicillin-Resistant
Staphylococcus aureus
, Sequence Type 239 (TW)
Authors: Holden Matthew T. G. , Lindsay Jodi A. , Corton Craig , Quail Michael A. , Cockfield Joshua D. , Pathak Smriti , Batra Rahul , Parkhill Julian , Bentley Stephen D. , Edgeworth Jonathan D.
Published: December 2009

The 3.1-Mb genome of an outbreak methicillin-resistant
Staphylococcus aureus
(MRSA) strain (TW20) contains evidence of recently acquired DNA, including two large regions (635 kb and 127 kb). The strain is resistant to a wide range of antibiotics, antiseptics, and heavy metals due to resistance genes encoded on mobile genetic elements and also mutations in housekeeping genes.
Expression of Factor H Binding Protein of Meningococcus Responds to Oxygen Limitation through a Dedicated FNR-Regulated Promoter
Authors: Oriente Francesca , Scarlato Vincenzo , Delany Isabel
Published: December 2009

Factor H binding protein (fHBP) is a surface-exposed lipoprotein in
Neisseria meningitidis
, which is a component of several investigational vaccines against serogroup B meningococcus (MenB) currently in development. fHBP enables the bacterium to evade complement-mediated killing by binding factor H, a key downregulator of the complement alternative pathway, and, in addition, fHBP is important for meningococcal survival in the presence of the antimicrobial peptide LL-37. In this study, we investigate the molecular mechanisms involved in transcription and regulation of the fHBP-encoding gene,
fhbp
. We show that the fHBP protein is expressed from two independent transcripts: one bicistronic transcript that includes the upstream gene and a second shorter monocistronic transcript from its own dedicated promoter, P

fhbp

. Transcription from the promoter P

fhbp

responds to oxygen limitation in an FNR-dependent manner, and, accordingly, the FNR protein binds to a P

fhbp

probe
in vitro
. Furthermore, expression in meningococci of a constitutively active FNR mutant results in the overexpression of the fHBP protein. Finally, the analysis of fHBP regulation was extended to a panel of strains expressing different fHBP allelic variants at different levels, and we demonstrate that FNR is involved in the regulation of this antigen in all but one of the strains tested. Our data suggest that oxygen limitation may play an important role in inducing the expression of fHBP from a dedicated FNR-regulated promoter. This implies a role for this protein in microenvironments lacking oxygen, for instance in the submucosa or intracellularly, in addition to its demonstrated role in serum resistance in the blood.
Beyond sudden death in the athlete: how to identify family members at risk
Authors: Quarta Giovanni , Lambiase Pier , Elliott Perry
Published: December 2009

Sudden death in young athletes is always a catastrophic event which focuses medical and public attention on the prevention of similar tragedies in other sporting participants. In this review article, we discuss the importance of evaluation of family members, who, by virtue of the familial nature of many of the diseases that cause sudden cardiac death, are potentially at risk of a similar outcome. We show that a systematic approach to the clinical evaluation of relatives of sudden death victims has a high yield in the identification of other affected family members and may prevent further catastrophic events in the same family.
Emerging impact of CTA/perfusion CT on acute stroke thrombolysis in a community hospital
Authors: Brant-Zawadzki M N , Brown D M , Whitaker L A , Peck W W
Published: December 2009

Our objective was to retrospectively review the emerging role of CT, CTA, and perfusion CT (pCT) in the hyperacute stroke population of a community hospital. We reviewed 50 consecutive patients' records and imaging studies, who were treated with thrombolytic therapy within 6 h of symptom onset. Multidetector CT, CTA, and pCT studies were evaluated. Subsequent CT, magnetic resonance, or angiographic studies when available were correlated. Patients' clinical data at admission and outcomes at discharge were evaluated. Complications were tabulated. Of the 50 patients treated with thrombolytics, 37 had CT/CTA/pCT, the others non-contrast CT only. CT blood volume defect was present in a total of 14 patients, presaging permanent infarct in all. Arterial clot was seen in 28/37 CTAs (carotid “T” 6, MCA 16, vertebrobasilar 6). Viable penumbra was shown in 20/37; rescued penumbra was depicted after treatment in 14.

39 patients were treated with intravenous, nine with intra-arterial, two with both forms of thrombolysis. Modified Rankin score showed clinical improvement in 58%, three patients had complete recovery. Subsequent bleed was shown in two (4%), symptomatic in one (2%). Two patients died. Our experience suggests advanced CT is more sensitive to ischemia than routine CT, that salvageable penumbra can be identified, and that triage of patients with acute stroke for thrombolysis with CT/CTA/pCT is more robust than routine CT alone, and may improve outcomes in the community hospital setting.
Hyperacute stent placement in acute cervical internal carotid artery occlusions: the potential role of magnetic resonance imaging
Authors: Jha R M , Hochberg L R , Hakimelahi R , Hirsch J A , González R G , Yoo A J
Published: December 2009

Cervical internal carotid artery (ICA) occlusions causing acute ischemic stroke have extremely poor outcomes without rapid re-establishment of cerebral perfusion. Given the high risk for early recurrent stroke, carotid stenting at the time of intra-arterial therapy may be crucial to improving outcomes. To our knowledge, there are only two prior case series that address intra-arterial reperfusion therapy and stent placement within six hours of stroke onset (the hyperacute period). We present two cases to further support the feasibility of this intervention in the hyperacute period, and report the potential utility of MRI in identifying patients most likely to benefit from this procedure.
Isolation and characterization of microsatellite loci for Euphorbia palustris (Euphorbiaceae)
Authors: Durka Walter
Published: December 2009

Swamp spurge ( Euphorbia palustris , Euphorbiaceae) is a large perennial species of wet grassland and swamps. Its natural habitats are fragmented and isolated both naturally and owing to habitat destruction by human activity. Thus the species is endangered and legally protected in Germany. This report describes seven novel polymorphic microsatellite loci that will be helpful to characterize genetic variation and to analyze the population genetic structure and levels of gene flow within and among populations. All loci were amplified within one multiplex polymerase chain reaction for two populations, yielding between 3 and 13 alleles per locus and high levels of heterozygosity. Trans-species amplification is reported for four Euphorbia species.
Rapid identification of the three homoeologues of the wheat dwarfing geneRhtusing a novel PCR-based screen of three-dimensional BAC pools
Authors: Febrer Melanie , Wilhelm Ed , Al-Kaff Nadia , Wright Jonathan , Powell Wayne , Bevan Michael W. , Boulton Margaret I.
Published: December 2009

A high-throughput two-step PCR strategy for the identification of selected genes from a BAC library derived from hexaploid wheat (16 974 Mbp) is described. The screen is based on the pooling of DNA from BAC clones into 675 “superpools” arrayed in a three-dimensional configuration. Each BAC clone is represented in three superpools to allow the identification of candidate 384-well plates of clones after the first round of PCR; identification is facilitated by an associated Perl script. A second round of PCR detects the specific BAC clone within the candidate plate that corresponds to the gene of interest. Thus, a single copy of the target gene can be identified from the library of over 700 000 clones (approximately 5 genome equivalents) by assaying only three 384-well plates. The pooling strategy was validated by screening the library with primers specific for the reduced height (Rht-1a) gene. Using relatively stringent selection criteria, 13 Rht-containing clones were identified from 17 candidate plates, and sequence analysis of the amplified products showed that all three Rht homoeologues were represented. Furthermore, the method confirmed the estimated coverage of the BAC library. Thus, this methodology allows the rapid and cost-effective identification of genes, and their homoeologues, from large-insert libraries of complex genomes such as hexaploid wheat.
Molecular genetic description of the cryptic wheat–Aegilops geniculataintrogression carrying rust resistance genesLr57andYr40using wheat ESTs and synteny with rice
Authors: Kuraparthy Vasu , Sood Shilpa , Gill Bikram S.
Published: December 2009

The cryptic wheat–alien translocation T5DL·5DS-5MgS(0.95), with leaf rust and stripe rust resistance genes Lr57 and Yr40 transferred from Aegilops geniculata (UgMg) into common wheat, was further analyzed. Molecular genetic analysis using physically mapped ESTs showed that the alien segment in T5DL·5DS-5MgS(0.95) represented only a fraction of the wheat deletion bin 5DS2-0.78-1.00 and was less than 3.3 cM in length in the diploid wheat genetic map. Comparative genomic analysis indicated a high level of colinearity between the distal region of the long arm of chromosome 12 of rice and the genomic region spanning the Lr57 and Yr40 genes in wheat. The alien segment with genes Lr57 and Yr40 corresponds to fewer than four overlapping BAC or PAC clones of the syntenic rice chromosome arm 12L. The wheat–alien translocation breakpoint in T5DL·5DS-5MgS(0.95) was further localized to a single BAC clone of the syntenic rice genomic sequence. The small size of the terminal wheat–alien translocation, as established precisely with respect to Chinese Spring deletion bins and the syntenic rice genomic sequence, further confirmed the escaping nature of cryptic wheat–alien translocations in introgressive breeding. The molecular genetic resources and information developed in the present study will facilitate further fine-scale physical mapping and map-based cloning of the Lr57 and Yr40 genes.
Molecular cloning, sequence characteristics, and polymorphism analyses of the tyrosinase-related protein 2 / DOPAchrome tautomerase gene of black-boned sheep (Ovis aries)
Authors: Deng Weidong , Tan Yuwen , Wang Xinyu , Xi Dongmei , He Yiduo , Yang Shuli , Mao Huaming , Gao Shizheng
Published: December 2009

Tyrosinase-related protein 2 (TYRP2) plays a pivotal role in the biosynthesis of eumelanin. Black-boned sheep have excessive melanin and eumelanin, resulting in dark (black) muscles and organs. This study was designed to investigate the effects of variants of the TYRP2 gene on black traits and coat colour of black-boned sheep. Melanin traits were measured in three populations of sheep (Nanping black-boned, Nanping normal, and Romney Marsh) and compared in this study. From the TYRP2 cDNA, all 8 exons and their flanking regions were amplified and characterized. Fifteen single nucleotide polymorphisms (SNPs) were identified in the exons and their flanking regions. Five exonic polymorphic sites, including two synonymous (c.93T>G and c.1140C>T) and three non-synonymous mutations (c.163C>T (p.R55W), c.605G>A (p.R202H), and c.1141A>G (p.T381A)), were retrieved. PCR-RFLP analysis of c.605G>A showed that the frequencies of allele G in the Nanping black-boned, Nanping normal, and Romney Marsh sheep were 0.632, 0.603, and 0.886, respectively. Sheep with the GG genotype had significantly (P < 0.05) lower tyrosinase activity, alkali-soluble melanin content, and ratio of eumelanin : total melanin than sheep with GA and AA genotypes when measured across all investigated samples but not when samples within each population of sheep were compared. However, there was no association of TYRP2 genotype at a single SNP position with coat colour across populations. Nonetheless, the two breeds with higher overall tyrosinase activity did produce darker and more varied coat colours than the breed with lower tyrosinase activity.
THE ADSORPTION OF METHYL ORANGE BY LYSOZYME
Authors: Colvin J. Ross
Published: December 2009

Adsorption isotherms for methyl orange on lysozyme at ionic strengths varying from 0.001 to 0.05, pH 5.5, are sigmoid. Increasing ionic strength shifts the inflection point of such isotherms to higher free anion concentrations. Binding of one methyl orange anion to a lysozyme molecule in 0.05 M acetate, pH 5.5, facilitates adsorption of nine others, with subsequent precipitation of the protein. This co-operative behavior is interpreted on the basis of a previously described theory of interacting hydration effects. The possible biological implications for similar systems are indicated.
CELL FREE "CHOLINE ACETYLASE" FROM LACTOBACILLUS PLANTARUM
Authors: Girvin Grace T. , Stevenson J. W.
Published: December 2009

The conventional methods employed to extract "choline acetylase" from animal tissues have been found not to be applicable to the extraction of the bacterial enzyme. A method has been developed for the extraction of a highly active cell free "choline acetylase" from Lactobacillus plantarum. The procedure involves disruption of lyophilized cells with glass powder and resolution of lipoprotein complexes through extraction of the cell debris with n-butyl alcohol followed by acetone drying and aequeous extraction of the enzyme from the acetone dried cell residue. The enzyme extract acetylates choline when incubated under anaerobic conditions with the substrates choline and acetate and requires the presence of ATP and cysteine. Coenzyme A markedly increases the activity of dialyzed extracts. Sodium pyruvate does not affect the synthesis of acetylcholine by the bacterial enzyme; sodium fluoride acts as a potent inhibitor. The activity of the extract is at least twice that reported for purified mammalian brain preparations and is 45% as potent as the highly active squid head ganglion enzyme.
STUDIES ON THE PRESERVATION OF BLOOD: I. GLYCOLYTIC BEHAVIOR OF BLOOD DURING STORAGE AT 5 °C. IN A MEDIUM CONTAINING AN EXCESS OF GLUCOSE
Authors: Pappius Hanna M. , Andreae Shirley R. , Woodford Vernon R. , Denstedt Orville F.
Published: December 2009

The chemical changes that occur in erythrocytes stored at 5 °C. in citrate–glucose medium have been studied. Glycolysis remains normal during the first two weeks of storage. About the 12th to 15th day an impairment in the system occurs at a stage in the glycolytic system before the production of diphosphoglycerate, thus causing a decrease of the concentration of diphosphoglycerate and an accumulation of pyruvic acid. From this time on, the over-all glycolytic activity of the cells is progressively decreased. These indications of failure could not be reversed or retarded by resuspension of the stored erythrocytes in fresh plasma, nor could the onset of failure be made to occur earlier by suspending fresh cells in 'old' plasma.
SUBCUTANEOUS FAT AND SKIN TEMPERATURE
Authors: LeBlanc Jacques
Published: December 2009

The subcutaneous fat explains to a large extent the individual differences, as well as the regional variations in the skin temperature, observed on the body. The insulation of the fat layer is 0.41 Clo per inch after one hour's exposure at 70° F., 1.18 at 60° F., and 1.96 at 50° F. The significance of these results, with reference to the thermal steady state of the body, is discussed.
STUDIES ON ACCLIMATIZATION AND ON THE EFFECT OF ASCORBIC ACID IN MEN EXPOSED TO COLD
Authors: LeBlanc J. , Stewart M. , Marier G. , Whillans M. G.
Published: December 2009

This experiment was planned to study the problem of acclimatization in humans and to determine the effect of ascorbic acid in men exposed to cold while being fed a normal or survival ration. Ascorbic acid has greatly improved the resistance of men exposed to cold and fed a survival ration. No beneficial effect was observed when the subjects were fed a normal ration. This difference in response may be due to the fact that the experimental conditions differed somewhat between these two experiments. In any event, the subjects on a restricted food intake were certainly under greater conditions of stress. Evidence of acclimatization was obtained with survival rations but not with normal rations. Some conclusions have been made on the use, by men exposed to cold, of survival rations composed exclusively of carbohydrates. Finally, it is estimated that 2800 calories is the daily requirement for men relatively inactive, wearing only shorts, low shoes, and socks, and exposed to an ambient temperature of 60°F.
THE ENZYMATIC SYNTHESIS OF CITRIC ACID BY CELL-FREE EXTRACTS OFASPERGILLUS NIGER
Authors: Ramakrishnan C. V. , Martin S. M.
Published: December 2009

Cell-free extracts of Aspergillus niger, N.R.C. 233, have been shown to contain the enzymes necessary to catalyze the synthesis of citrate from ATP, acetate, and oxalacetate. The "condensing enzyme", which catalyzes the condensation of acetyl-coenzyme A and oxalacetate to yield citrate, has been isolated and purified approximately 50-fold by a combination of steps involving ammonium sulphate fractionation and calcium phosphate gel adsorption.
LECITHINASE SYSTEMS IN SUGAR BEET, SPINACH, CABBAGE, AND CARROT
Authors: Kates Morris
Published: December 2009

Lecithinase activity of aqueous extracts of sugar beet, spinach, or cabbage leaves, and of carrot root was found to be associated entirely with the plastid fractions, separated by high-speed centrifugation. The supernatant cell sap–cytoplasm fractions were not only inactive but actually inhibitory. The rate of enzymatic liberation of choline from lecithin by all plastid fractions was found to be greatly increased by saturation with diethyl ether. The influence of pH, enzyme concentration, substrate concentration, and temperature on the rate of ether-activated choline liberation was studied and optimum conditions for the reaction were determined. Under optimum conditions, liberation of choline from lecithin by each of the plastid fractions was rapid and was accompanied by a much slower liberation of inorganic and water-soluble organic phosphate; liberation of phosphates was much greater with spinach than with the other species. Thermal inactivation and fluoride inhibition of the enzyme systems were also studied.
DESOXYRIBONUCLEIC ACID CONTENT AND CELL DENSITY IN BRAIN AND HUMAN BRAIN TUMORS
Authors: Heller Irving H. , Elliott K. A. C.
Published: December 2009

The desoxyribonucleic acid (DNA) content per nucleus and per unit weight of tissue have been determined chemically in normal cerebral cortex, cerebellar cortex, and corpus callosum of man, dog, and cat and in various human brain tumors. Nuclear densities have been calculated from these determinations. Corpus callosum contains approximately the same total number of cells as does cerebral cortex; cerebellar cortex contains several times this number. The nuclear density in tumors is usually higher than in cerebral cortex or corpus callosum. The amount of DNA per nucleus in primary brain tumors is considerably higher than in normal tissue. The average DNA per nucleus in the more primitive and malignant tumors appears to be higher than in the more differentiated tumors. Calculations indicate that the increase in the DNA per nucleus in brain tumors is more likely to be due to polyploidy than to increased mitotic activity.
THE EFFECT OF SODIUM BENTONITE ADMINISTRATION ON VITAMIN A METABOLISM IN THE RAT
Authors: Laughland D. H. , Phillips W. E. J.
Published: December 2009

The inclusion of sodium bentonite in the diet severely limited the ability of vitamin A deficient rats to store the vitamin in the liver. This effect was observed both with vitamin A and with the provitamin β-carotene. Moreover, the liver weight per 100 gm. body weight was found to be less in most of the groups receiving sodium bentonite than in control groups. The results may be interpreted in terms of a physical adsorption of vitamin A or β-carotene on sodium bentonite present in the small intestine. Sodium bentonite cannot be regarded as an inert ingredient of the diet of rats and its prolonged administration might be expected to have deleterious effects.
THE ROLE OF ALKALINE PHOSPHATASE IN INTESTINAL ABSORPTION: II. THE EFFECTS OF VARIOUS CARBOHYDRATES ON LEVELS OF THE ENZYME IN INTESTINAL MUCOSA
Authors: Tuba Jules , Dickie Nestor
Published: December 2009

Adult male rats were deprived of food for five days. Various groups of these animals were then offered cellulose or cellulose mixed with one of seven other carbohydrates. Six hours after food was placed before them, the animals were killed by decapitation, and a portion of the intestine from each rat was homogenized. Intestinal alkaline phosphatase estimations indicated (1) that the activity of the enzyme was increased significantly by the ingestion of glucose, galactose, fructose, and mannose, whereas (2) there was not a statistically significant elevation of the enzyme level in those animals which had been fed cellulose, arabinose, xylose, or sucrose. This would appear to suggest that alkaline phosphatase is involved in the intestinal absorption of some monosaccharides.
METABOLISM OF MAMMALIAN ERYTHROCYTES: VII. THE GLUTATHIONE REDUCTASE OF THE MAMMALIAN ERYTHROCYTE
Authors: Francoeur Marc , Denstedt Orville F.
Published: December 2009

In the presence of the stroma-free hemolyzate of rat, rabbit, and human erythrocytes, GSSG has been shown to be reduced by G-6-P and TPN+, HDP and DPN+, or by chemically reduced TPNH and DPNH. Evidence has been presented that DPNH–GSSG reductase requires a cofactor for full activity.
Reinforced earth retaining wall analysis and design
Authors: Laba J. T. , Kennedy J. B.
Published: November 2009

An experimental and theoretical study was conducted to assess the maximum tensile forces mobilized in a reinforced earth retaining wall, subjected to a vertical surcharge strip load or the combined action of vertical and horizontal surcharge strip loads. A simple design method for determining the maximum magnitude of the tensile force and its distribution with depth of the reinforced earth backfill was developed. The design method takes into consideration the ability of the reinforced earth wall system to retain its internl equilibrium by stress transfer from overstressed regions to those regions where the reinforcing elements have not yet reached their full frictional or strength capacity. The effect of the magnitude and location of the strip load on this phenomenon of stress transfer is shown. Favourable comparisons were obtained between the results given by the proposed design method and those from model tests. Key words: reinforced earth, vertical and horizontal surcharge strip load, reinforcing elements, internal stability, stress transfer.
Flexural behavior of frozen soil
Authors: Soo Sweanum , Wen Robert K. , Andersland Orlando B.
Published: November 2009

Plain and reinforced frozen sand beams were loaded incrementally in pure bending at −6 and −10 °C. For plain beams, the deflection rate (during secondary creep) showed a linear relationship with applied load on a log–log scale while experimental results of beams reinforced with a single 4.76 mm diameter steel bar showed a bilinear relationship. The observed deflection behavior was a result of the combined effects of soil creep in tension, compression, and adfreeze bond at the reinforcement/frozen soil interface.To analyze the flexural behavior of frozen soil, one-dimensional finite elements with different creep properties in tension and in compression were used in conjuction with the power creep law or the hyperbolic sine creep law. For the secondary creep condition and the power creep law, analytical solutions for frozen soil beam behavior are presented. Numerical results indicate reasonable agreement with experimental results. Key words: adfreeze bond, creep properties, flexural strength, frozen soils, reinforced earth.
Pore pressure generation and dissipation in dense sands under cyclic loading
Authors: Mitchell Robert J. , Dubin B. Ian
Published: November 2009

A triaxial test system capable of subjecting samples of saturated soil to load controlled cyclic loading under various conditions of drainage is described. The system was used to apply cyclic loading, from compression to extension, at a frequency of 0.06 Hz (4 cycles/min) on a relatively dense saturated sand. This relatively low loading frequency is considered applicable to problems associated with wave or wind loadings.The results of a series of undrained cyclic loading tests are presented. This data generally supports concepts developed by previous research on cyclic loadings of sands.Partial drainage was found to be effective in counteracting pore water pressure buildup at this low cyclic frequency. Failure of one test sample was prevented by drainage even though cyclic mobility had been initiated. Data obtained from this type of controlled drainage testing can be used directly as model study data or can be combined with pore pressure dissipation theory to evaluate the risk of failure under cyclic loading and to design relief measures, such as drainage wells, to prevent the initiation of cyclic mobility in dense sands. Key words: cyclic loading, triaxial, sand, undrained, partial drainage, cyclic mobility, offshore.
Direct halogenation of organic compounds with halides using oxone in water — A green protocol
Authors: Firouzabadi H. , Iranpoor N. , Kazemi S.
Published: December 2009

Direct bromination and iodination of various aromatic compounds with NaBr and NaI using oxone (2KHSO5·KHSO4·K2SO4) in water was accomplished successfully in high-to-excellent yields. The main benefit of this protocol is the performance of the reactions in water in the presence of a harmless oxidant without the use of any organic co-solvents. Using NaBr and NaI as the safe sources of halogens is another advantage of the protocol. This method is easily applicable to the large-scale operations. We have also applied this method successfully for the iodocyclization of an unsaturated alcohol and an unsaturated carboxylic acid.
Chemo- and regio-selective functionalization of Morita–Baylis–Hillman bromides with anthranilic acid
Authors: Zulykama Yusuf , Uma Ulagamani , Devi Palanisamy Chitra , Perumal Paramasivan T.
Published: December 2009

Nucleophilic substitution products of Morita–Baylis–Hillman adducts and their derivatives are valuable synthons. In an attempt to ameliorate the functionality of these functionalized motifs, we report the regio- and chemo-selective functionalization of Morita–Baylis–Hillman bromides with anthranilic acid.
Development of additive isotropic site potential for exchange-repulsion energy, based on intermolecular perturbation theory
Authors: Yokogawa Daisuke , Sato Hirofumi , Gusarov Sergey , Kovalenko Andriy
Published: December 2009

We have developed an additive spherical site potential for exchange-repulsion energy by applying the local density approximation in Hilbert space, the local-site approximation, and the s-type auxiliary basis set to the equation derived from intermolecular perturbation theory. The method efficiently addresses the decomposition of molecular interactions derived from quantum chemistry into additive spherical site potentials, required as force field input in a statistical-mechanical, reference interaction site model (RISM and 3D-RISM), molecular theory of solvation. The present method reproduces the exchange-repulsion energy between simple molecules obtained from quantum chemical calculations.
Multi-component supramolecular synthesis of spirooxindoles catalyzed by β-cyclodextrin in water
Authors: Sridhar Regati , Srinivas Boga , Madhav Bandaru , Reddy Vutukuri Prakash , Nageswar Yadavalli Venkata Durga , Rao Kakulapati Rama
Published: December 2009

A neutral and efficient one-pot three-component aqueous-phase synthesis is developed for various spirooxindole derivatives from isatin, malononitrile, and 1,3-dicarbonyl compounds in high yields by supramolecular catalysis involving β-cyclodextrin. The β-cyclodextrin can be recovered and reused a number of times without any loss of activity.
Introducing the ACM Transactions on Computing Education
Authors: Tenenberg Josh , McCartney Robert
Published: December 2009

The ACM Transactions on Computing Education (TOCE) represents a name change and a broadening of scope for the ACM Journal on Educational Resources on Computing (JERIC). The topics covered by this new journal will range across diverse aspects of computing education: traditional computer science, computer engineering, software engineering, information technology, and informatics; emerging aspects of computing; and applications of computing to other disciplines, such as computational biology. The common characteristics shared by these articles are a scholarly approach to teaching and learning, a broad appeal to educational practitioners, and a clear connection to student learning.
STREAM
Authors: Caspersen Michael E. , Kolling Michael
Published: December 2009

Programming is recognized as one of seven grand challenges in computing education. Decades of research have shown that the major problems novices experience are composition-based---they may know what the individual programming language constructs are, but they do not know how to put them together. Despite this fact, textbooks, educational practice, and programming education research hardly address the issue of teaching the skills needed for systematic development of programs.

We provide a conceptual framework for incremental program development, called Stepwise Improvement, which unifies best practice in modern software development such as test-driven development and refactoring with the prevailing perspective of programming methodology, stepwise refinement. The conceptual framework enables well-defined characterizations of incremental program development.

We utilize the conceptual framework to derive a programming process, STREAM, designed specifically for novices. STREAM is a carefully down-scaled version of a full and rich agile software engineering process particularly suited for novices learning object-oriented programming. In using it we hope to achieve two things: to help novice programmers learn faster and better while at the same time laying the foundation for a more thorough treatment of more advanced aspects of software engineering. In this article, two examples demonstrate the application of STREAM.

The STREAM process has been taught in the introductory programming courses at our universities for the past three years and the results are very encouraging. We report on a small, preliminary study evaluating the learning outcome of teaching STREAM. The study indicates a positive effect on the development of students’ process competences.
Training Students to Work Effectively in Partially Distributed Teams
Authors: Ocker Rosalie , Rosson Mary Beth , Kracaw Dana , Hiltz S. Roxanne
Published: December 2009

Information technology teams are often partially distributed teams (PDTs). A PDT consists of two or more subteams that are separated geographically. This articles describes research focused on the use of PDTs to engage students in “real world” IT team learning about the subject matter while also teaching them the skills they will need to work in global software development teams. Findings from a large-scale international study indicate that the introduction of training modules enhanced perceived learning of appropriate PDT teaming behaviors; students with training reported improved shared team identification, trust, awareness, coordination, competence, and conflict with respect to distant subteam members, and higher overall team performance.
Extending the Engagement Taxonomy
Authors: Myller Niko , Bednarik Roman , Sutinen Erkki , Ben-Ari Mordechai
Published: December 2009

As collaborative learning in general, and pair programming in particular, has become widely adopted in computer science education, so has the use of pedagogical visualization tools for facilitating collaboration. However, there is little theory on collaborative learning with visualization, and few studies on their effect on each other. We build on the concept of the
engagement taxonomy
and extend it to classify finer variations in the engagement that result from the use of a visualization tool. We analyze the applicability of the taxonomy to the description of the differences in the collaboration process when visualization is used. Our hypothesis is that increasing the level of engagement between learners and the visualization tool results in a higher positive impact of the visualization on the collaboration process. This article describes an empirical investigation designed to test the hypothesis. The results provide support for our extended engagement taxonomy and hypothesis by showing that the collaborative activities of the students and the engagement levels are correlated.
Seamless Merging of Hypertext and Algorithm Animation
Authors: Karavirta Ville
Published: December 2009

Online learning material that students use by themselves is one of the typical usages of algorithm animation (AA). Thus, the integration of algorithm animations into hypertext is seen as an important topic today to promote the usage of algorithm animation in teaching. This article presents an algorithm animation viewer implemented purely using HTML and JavaScript. The viewer is capable of viewing animations in
Xaal
(eXtensible Algorithm Animation Language), a language designed to allow easy transformation of AAs between various formats. This solution is extremely suited for use in hypertext learning material due to the advanced interaction possibilities between learning material (HTML) and the animation.
A Visualization-Based Computer Science Hypertextbook Prototype
Authors: Rößling Guido , Vellaramkalayil Teena
Published: December 2009

Hypertextbooks for Computer Science contents present an interesting approach to better support learners and integrate algorithm animations into the learning materials. We have developed a prototype for integrating a selection of the functionality of such a hypertextbook into the established Moodle LCMS. This article describes the goals and realization of this module together with an example.
Adding Test Generation to the Teaching Machine
Authors: Bruce-Lockhart Michael , Norvell Theodore , Crescenzi Pierluigi
Published: December 2009

We propose an extension of the Teaching Machine project, called Quiz Generator, that allows instructors to produce assessment quizzes in the field of algorithm and data structures quite easily. This extension makes use of visualization techniques and is based on new features of the Teaching Machine that allow third-party visualizers to be added as plugins and on new scripting capabilities. Using these new capabilities, five quiz types have already been produced, which can be applied to any algorithm and/or data structure for which the necessary visualizer plugins exist.
Geometry-aware analysis of high-dimensional visual information sets
Authors: Kokiopoulou Effrosyni , Frossard Pascal
Published: December 2009

Over the past few decades we have been experiencing a data explosion; massive amounts of data are increasingly collected and multimedia databases, such as YouTube and Flickr, are rapidly expanding. At the same time rapid technological advancements in mobile devices and vision sensors have led to the emergence of novel multimedia mining architectures. These produce even more multimedia data, which are possibly captured under geometric transformations and need to be efficiently stored and analyzed. It is also common in such systems that data are collected distributively. This very fact poses great challenges in the design of effective methods for analysis and knowledge discovery from multimedia data. In this thesis, we study various instances of the problem of classification of visual data under the view-point of modern challenges. Roughly speaking, classification corresponds to the problem of categorizing an observed object to a particular class (or category), based on previously seen examples. We address important issues related to classification, namely flexible data representation for joint coding and classification, robust classification in the case of large geometric transformations and classification with multiple object observations in both centralized and distributed settings.
Global metabolic consequences of the chromogranin A-null model of hypertension: transcriptomic detection, pathway identification, and experimental verification
Authors: Friese Ryan S. , Gayen Jiaur R. , Mahapatra Nitish R. , Schmid-Schönbein Geert W. , O'Connor Daniel T. , Mahata Sushil K.
Published: December 2009

Chromogranin A (CHGA) has a crucial role in formation of regulated secretory granules in neuroendocrine tissues and is also a prohormone that is proteolytically processed into peptides with diverse and complex actions. CHGA and several of its peptide products, including catestatin and pancreastatin, are implicated in pathogenesis of essential hypertension, insulin resistance, and the metabolic syndrome. The Chga knockout mouse (Chga KO) displays severe hypertension coupled with reduction in size, number, and density of regulated secretory granules. We performed genome-wide transcriptome profiling in Chga KO adrenal gland and liver for insight into biochemical and physiological systems altered in this monogenic mouse model of hypertension. Adrenal gene expression pathway prediction of enhanced insulin sensitivity ( P = 0.03) in Chga KO was confirmed with glucose, insulin, and homeostasis model assessment of insulin resistance (HOMA-IR) measurements: blood glucose was normal in Chga KO, blood insulin was reduced 4.5-fold ( P < 0.0001), and HOMA-IR was decreased 3.8-fold ( P < 0.002). Remarkably, such observations conclusively dissociate fundamental features of the metabolic syndrome in this monogenic hypertension model. Exogenous pancreastatin treatment restored insulin sensitivity in the Chga KO to near-normal levels. Gene expression predictions of decreased adrenal cholesterol biosynthesis ( P < 0.001) and increased hepatic cholesterol biosynthesis ( P < 0.001) were verified with tissue total cholesterol assays: Chga KO adrenal cholesterol decreased 1.8-fold ( P = 0.039) and hepatic cholesterol increased 1.8-fold ( P = 0.018). Transcriptional regulatory network prediction identified sets of transcription factors that may provide insight into the unclear mechanistic links among CHGA, cholesterol, insulin sensitivity, and the metabolic syndrome. These experiments demonstrate, for the first time, that genetic variation at the CHGA locus impacts insulin sensitivity and tissue cholesterol levels in an intact, living organism. The Chga KO may constitute a unique model for studying the relationship between the CHGA locus and disease phenotypes of the metabolic syndrome.
Management for Patients with De Novo or Recurrent Tumors in the Residual Kidney after Surgery for Nonfamilial Bilateral Renal Cell Carcinoma
Authors: Hara Noboru , Nishiyama Tsutomu , Yoshimura Norihiko , Takaki Satoshi , Yamakado Kyoichiro , Kitamura Yasuo , Suzuki Kazuya , Takahashi Kota
Published: December 2009

The tumor de novo in the residual kidney after surgery for nonfamilial bilateral renal cell carcinoma (RCC) is problematic. We reviewed 5 patients who experienced such a situation. Three patients had had metachronous bilateral RCC, treated with radical nephrectomy in one kidney and nephron-sparing surgery (NSS) in the other. Two patients had had synchronous disease; one patient had received radical nephrectomy and NSS, and the other bilateral NSS. The 5 patients had another solid mass/de novo tumor in the residual kidney 16–88 (mean 46.8) months after surgery. For the tumor de novo in earlier years (1992–1999), one patient underwent surgery and hemodialysis, and the other selected a conservative observation. In recent years (2000–2007), one patient was conservatively observed; the remaining 2 received computerized-tomography-guided radiofrequency ablation, and the local tumors were well controlled postoperatively for 20 and 12 months with their renal function unimpaired. Ablative techniques can potentially strike a balance between oncological and nephrological outcomes in patients with sporadic multiple RCC, successful management of which was difficult previously.