bluuebunny/crossref_metadata_2025 huggingface dataset:
Polymeric alkenoxy amino acid surfactants: III. Chiral separations of binaphthyl derivatives
Authors: Rizvi Syed Asad Ali , Simons David Nicholas , Shamsi Shahab A.
Published: February 2004

Micellar electrokinetic chromatography (MEKC) was investigated for the enantiomeric separations of three binaphthyl derivatives ((±)‐1,1'‐bi‐(2‐naphthol) (BOH), (±)‐1,1'‐binaphthyl‐2,2'‐diyl hydrogenphosphate (BNP), and (±)‐1,1'‐binaphthyl‐2,2'‐diamine (BNA)) using two recently synthesized chiral polymeric surfactants (polysodium N‐undecenoxy carbonyl‐L‐leucinate (poly‐L‐SUCL) and polysodium N‐undecenoxy carbonyl‐L‐isoleucinate (poly‐L‐SUCIL)) in our laboratory [33]. Enantiomeric separation (resolution and selectivity) of the binaphthyl derivatives was influenced by polymerization concentration of the monomeric surfactant, pH, type and concentration of the background electrolyte (BGE) as well as concentration of the polymeric surfactant. Two BGEs (dibasic phosphate and Tris‐borate) were compared for this study. The use of dibasic phosphate as BGE in poly‐L‐SUCL provides baseline resolution of (±) BOH and (±) BNP, however, no resolution and selectivity at all was observed for (±) BNA. A similar approach was adopted with Tris‐borate‐poly‐L‐SUCL system at fixed pH 10.1, which resulted in baseline resolution of all three binaphthyl derivatives. Although Rs of binaphthyl derivatives was always higher and electroosmotic flow (EOF) was always lower using Tris‐borate than with dibasic phosphate, the selectivity values for the two buffer systems did not differ significantly. In addition, it was found that poly‐L‐SUCL provided better enantiomeric resolution and selectivity for (±) BOH and (±) BNA, while poly‐L‐SUCIL provided enhanced enantiomeric resolution but similar enantioselectivity for (±) BNP. This indicates that the depth of analyte penetration into the palisade layer and the micellar core are responsible for chiral recognition of hydrophobic analyte (e.g., (±) BOH, and (±) BNA) whereas for moderately hydrophobic analyte (e.g., (±) BNP) interaction with the polar head group seems to dictate chiral recognition. Simultaneous enantioresolution of all three binaphthyl derivatives was possible in a single electrophoretic run using either poly‐L‐SUCL or poly‐L‐SUCIL. Further comparison of the two polymeric surfactants showed that poly‐L‐SUCL provided slightly longer analysis time than poly‐L‐SUCIL but the use of the former polymeric surfactant should be preferred due to its ability to provide complete baseline resolution and higher selectivity of all the three atropisomers with a wider chiral window.
Optimization of sample stacking for the simultaneous determination of nonsteroidal anti‐inflammatory drugs with a wall‐coated histidine capillary column
Authors: Pai Yi‐Fen , Lin Chun‐Chi , Liu Chuen‐Ying
Published: February 2004

A wall‐coated histidine capillary column was developed for the on‐line preconcentration of nonsteroidal anti‐inflammatory drugs (NSAIDs) in capillary electrochromatography (CEC). A wide variety of experimental parameters, such as the sample buffer, background electrolyte (BGE) composition, concentration, sample plug lengths, water plug, and the effect of organic modifiers were studied. The relationship between peak height and injection times for the NSAIDs by variation of sample and BGE buffer concentration was investigated. On addition of sodium chloride (0.3–0.6%) to the sample zone, the stacking efficiency was increased. With acetate buffer (100 mM, pH 5.0)/ethanol (20% v/v) as BGE and sample solution in acetate buffer (0.2 mM, pH 5.0)/ethanol (20% v/v)/NaCl (0.3% w/v), NSAIDs could be determined at low μM levels without sample matrix removal. The detection limit was 0.096 μM for indoprofen, 0.110 μM for ketoprofen, 0.012 μM for naproxen, 0.023 μM for ibuprofen, 0.110 μM for fenoprofen, 0.140 μM for flurbiprofen, and 0.120 μM for suprofen. The method could be successfully applied to the simultaneous determination of NSAIDs in urine. The recoveries were better than 82% for all the analytes. The present method enables simple manipulation with UV detection for the determination of NSAIDs at low concentration levels in complex matrix samples.
The use of novel water‐in‐oil microemulsions in microemulsion electrokinetic chromatography
Authors: Altria Kevin D. , Broderick Margo F. , Donegan Sheila , Power Joe
Published: February 2004

We describe the novel use of water‐in‐oil (W/O) microemulsions to achieve unique separations in microemulsion electrokinetic chromatography (MEEKC). The choise and concentration of the buffer type, surfactant and co‐surfactant were all examined and optimized. Separations of a range of neutral and acidic analytes was shown to be markedly different to that obtained by (oil‐in‐water) O/W MEEKC. Neutral solutes are separated by virtue of their solubility (log P) values in O/W MEEKC with the more water‐insoluble solutes migrating last. This separation process does not occur in W/O, as neutral solutes are not separated in order of log P.
Antimutagenic and antiradical properties of flavones from the roots of Scutellaria baicalensis Georgi
Authors: Wożniak Dorota , Lamer‐Zarawska Eliza , Matkowski Adam
Published: February 2004

The four flavonoids baicalin, baicalein, wogonoside, and wogonin have been isolated from Scutellaria baicalensis (Lamiaceae) root extract as main bioactive components. We evaluated their antimutagenic activity as potential chemopreventive natural substances using the Ames test. Free radical scavenging properties have also been measured with the 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) assay. Both crude extract and isolated flavone glycosides and aglycones have antimutagenic and free radical scavenging properties. The lipophilic flavone baicalein has been confirmed to be the most powerful antimutagen among the compounds tested.
Properties of wheat bran polyphenol oxidase
Authors: Soysal Çiǧdem , Söylemez Zerrin
Published: February 2004

Polyphenol oxidase (PPO) obtained from wheat bran catalyzed the oxidation of 4‐methyl catechol. Phenolic compounds found naturally in crude extract played role as an endogeneous substrate and activity of crude extract needed correction. Activity versus enzyme concentration gave a linear plot at high substrate concentration whereas a nonlinear plot was obtained at low substrate concentration which proved the presence of endogeneous substrate. Adsorption on celite and extraction with polyvinylpyrrolidone (PVPP) caused the removal of phenols. Adsorption of PPO on celite yielded a 4‐fold increase in specific activity whereas extraction with PVPP yielded a 2.5‐fold increase in specific activity compared to the crude extract. The kinetics of PPO catalyzed oxidation obeyed Michaelis‐Menten model; Km and Vmax values were found as 218 mM and 99 μM/min, respectively. The enzyme was inhibited by ethyl alcohol, dithiothreitol (DTT) and isoproterenol and exhibited heat stability up to a temperature of 90°C. The optimum pH of the enzyme was found to be 5.0.
Quality and safety evaluation of genetically modified potatoes Spunta with Cry V gene: Compositional analysis, determination of some toxins, antinutrients compounds and feeding study in rats
Authors: El Sanhoty Rafaat , Abd El‐Rahman Ahamed Ali , Bögl Klaus Werner
Published: February 2004

The aim of this study was to evaluate the composition, nutritional and toxicology safety of GM potato Spunta lines compared to that of conventional potato Spunta. Compositional analyses were conducted to measure the proximate chemical composition with references to 14 components, total solid, protein, lipid, crude fibre, ash, carbohydrate, starch, reducing sugar, nonreducing sugar, sodium, calcium, potassium, phosphorus, and ascorbic acid. Some toxins and anti‐nutrients compounds were determined. Feeding study of GM potatoes line (G2 and G3) in rats were done for 30 days. Four groups of albino rats were used for studying the effect and the safety assessment of GM potatoes Spunta G2 and G3. Group (I) was fed on control basal diet, group (II) was fed on control diet plus 30% freeze‐dried nongenetically modified potato Spunta, group (III) was fed on control diet plus 30% freeze‐dried genetically modified potato Spunta, and group (IV) was fed on control diet plus 30% freeze‐dried genetically modified potato Spunta GMO G3. There were no significant differences between GM potatoes G2, G3, and Spunta control potato line in the proximate chemical composition. The levels of glycoalkaloids in transgenic potato tubers and nontransgenic were determined and there were also no significant differences between the GM potatoes and conventional potato line, the levels were in agreement with a safety level recommended by FAO/WHO (200 mg/kg) for acute toxicity. Protease inhibitor activity and total phenol were estimated and no significant differences between the GM potatoes line and conventional potato Spunta line were found. During the period tested, rats in each group (I, II, III, IV) grew well without marked differences in appearance. No statistical difference were found in food intake, daily body weight gain and feed efficiency. But there is a slightly significant difference in finally body weight between the control group and experimental groups. No significant difference were found in serum biochemical value between each groups, and also between relative organs weight (liver, spleen, heart, kidney, testes). From these results, it can be concluded that the GM potatoes Spunta line (G2 and G3) with Cry V gene are confirmed to have nearly the composition and biochemical characteristics as non‐GM potato Spunta.
Effects of extrusion variables on the properties of waxy hulless barley extrudates
Authors: Köksel Hamit , Ryu Gy‐Hyung , Basman Arzu , Demiralp Hande , Ng Perry K. W.
Published: February 2004

The objective of this research was to investigate the extrudability of waxy hulless barley flour under various extrusion conditions. Waxy hulless barley flour was processed in a laboratory‐scale corotating twin‐screw extruder with different levels of feed moisture content (22.3, 26.8, and 30.7%) and die temperature (130, 150, and 170°C) to develop a snack food with high β‐glucan content. The effects of extrusion condition variables (screw configuration, moisture, and temperature) on the system variables (pressure and specific mechanical energy), the extrudate physical properties (sectional expansion index, bulk density), starch gelatinization, pasting properties (cold peak viscosity, trough viscosity, and final viscosity), and β‐glucan contents were determined. Results were evaluated by using response surface methodology. Increased extrusion temperature and feed moisture content resulted in decreases in exit die pressure and specific mechanical energy values. For extrudates extruded under low shear screw configuration (LS), increased barrel temperature decreased sectional expansion index (SEI) values at both low and high moisture contents. The feed moisture seems to have an inverse relationship with SEI over the range studied. Bulk density was higher at higher moisture contents, for both low and high barrel temperatures, for samples extruded under high shear screw configuration (HS) and LS. Cold peak viscosities (CV) were observed in all samples. The CV increased with the increase in extrusion temperature and feed moisture content. Although β‐glucan contents of the LS extrudates were comparable to that of barley flour sample, HS samples had generally lower β‐glucan contents. The extrusion cooking technique seems to be promising for the production of snack foods with high β‐glucan content, especially using LS conditions.
Genotypic effects on glucosinolates and sensory properties of broccoli and cauliflower
Authors: Schonhof Ilona , Krumbein Angelika , Brückner Bernhard
Published: February 2004

The objective of this study was to investigate the influence that the species, form or cultivar exerts on the glucosinolate spectrum for glucosinolates and free sugars in selected vegetable species of the Brassica genus (Brassica oleracea var. italica Plenck, Brassica rapa var. alboglabra and Brassica oleracea var. botrytis L.). The results showed significant differences amongst the cultivar groups for the glucosinolate proportions as well as the contents of health‐promoting and flavour‐influencing alkyl, alkenyl and indole glucosinolates. The clear differences in the proportions of glucosinolates amongst the groups were not significantly influenced by the weather, although the absolute glucosinolate contents were. Interestingly, the species, forms and cultivars diverged in their external and internal sensory attributes, for example, colour, taste properties such as bitter and sweet, flavour such as green/grassy, spicy, broccoli‐like, cabbage‐like, cauliflower‐like, kohlrabi‐like, leek‐like and mouth‐feel pungent. Differences in the sensory attributes led to different consumer acceptability based on first impressions judged on colour, flavour and overall liking. Consumers were seen to prefer cultivars with a bright colour, a lower level of bitter tasting glucosinolates (alkenyl and indole glucosinolates) and a higher sucrose content. Significant correlations were determined between the compound concentrations, the descriptively determined sensory properties and the consumer scores. Here, we identified properties of broccoli and cauliflower which, when optimised to the tastes of the consumer, could boost their acceptability.
Tocopherol composition of deodorization distillates and their antioxidative activity
Authors: Nogala‐Kalucka Malgorzata , Korczak Jozef , Wagner Karl‐Heinz , Elmadfa Ibrahim
Published: February 2004

During the last stage of plant oil refining, deodorization distillates containing very important biological substances such as tocopherols, sterols, terpenoids or hydrocarbons are formed as a by‐products. This study aimed at evaluating the content and antioxidant capacity of tocopherol concentrates from deodorization distillates obtained after the refining of rapeseed, soybean and sunflower oil. The majority of the matrix substances were eliminated from deodorization distillates by freezing with an acetone solution at –70°C. The tocopherol concentrates obtained in this way contained approximately fivefold more tocopherols than the quantity in condensates after deodorization. Antioxidant activity was investigated by observing the peroxide value at 25°C and using the Oxidograph test. The test medium was lard enriched with the tocopherol concentrates of the three plant oils versus single, synthetic α‐, γ‐ and δ‐tocopherols (‐T), which served for comparison. In these model systems, all investigated tocopherol concentrates exhibited antioxidant capacity. Their antioxidant effect was significantly lower than that of single δ‐T and γ‐T, but significantly higher than α‐T. The results prove that natural tocopherol concentrates obtained from plant oils are valuable food antioxidants and they also increase the biological and nutritional value of food especially when administered to animal fats or food of animal origin. Tocopherol concentrates can fully replace synthetic antioxidants that have been used thus far.
In vitro starch digestibility changes during storage of maize flour tortillas
Authors: Agama‐Acevedo Edith , Rendón‐Villalobos Rodolfo , Tovar Juscelino , Paredes‐López Octavio , Islas‐Hernández José Juan , Bello‐Pérez Luis Arturo
Published: February 2004

Nixtamalized maize flours elaborated by four factories in Mexico were used for tortilla preparation. Samples were stored at 4°C for up to 72 h and their in vitro starch digestibility features were evaluated. Moisture content was different between flour and tortilla but no evident relation could be established. Protein and lipid levels were lower in tortillas than in flour but ash content was not different in both samples. A decrease in available starch content was observed upon 48 h cold storage (4°C), changes that were concomitant with increased total resistant starch (RS) levels. These changes were due mainly to retrogradation, as suggested by the increased retrograded resistant starch (RRS) levels recorded in stored tortillas; in some samples, RRS represented up to 100% of total RS. The digestion (α‐amylolysis) rate (DR) of freshly prepared tortillas differed for the various samples. Although the amylolysis patterns for fresh and 72 h‐stored tortillas were similar, lower DR values were shown for the stored materials. The differences found among the various tortilla samples may be due to variations in processing conditions during commercial maize flour preparation, and to the use of different maize varieties.
Characterization and physicochemical properties of some potential fibres derived from Averrhoa carambola
Authors: Chau Chi‐Fai , Chen Chien‐Hung , Lee Mao‐Hsiang
Published: February 2004

The pomace of Averrhoa carambola (carambola) was found to possess a high level of insoluble fibre‐rich fractions (FRFs) including insoluble dietary fibre, alcohol‐insoluble solid, and water‐insoluble solid (46.0–58.2 g/100 g of pomace). These FRFs were mainly composed of pectic substances and hemicellulose. The physicochemical properties of these FRFs (e. g., water‐holding capacities, swelling properties, and cation‐exchange capacities) were significantly (P < 0.05) higher than those of cellulose. The apparent abilities of these FRFs to adsorb glucose and reduce amylase activity implied that they might help control postprandial serum glucose. These results recommended the consumption and application of the insoluble FRFs as low‐calorie bulk ingredients in fibre enrichment. Further investigations on the in vivo hypoglycemic effect and other physiological effects of these FRFs using animal‐feeding experiments are underway.
Alimentary chromium, nickel, and selenium intake of adults in Poland estimated by analysis and calculations using the duplicate portion technique
Authors: Marzec Zbigniew
Published: February 2004

Chromium, nickel, and selenium have been known to be essential for proper functioning of human organisms. Since the Polish data concerning their content in diets are scarce, the study was undertaken to examine the levels of these elements in daily food rations (DFRs) in adults from the Lublin region in 1990, 1993, 1997, 1998, and 2002. The aim was to compare the results obtained by the calculation technique based on the national database with those of the DFR chemical analysis. Moreover, the study was to determine quantitative shares of the individual food groups in the daily pool of the elements examined. Determinations of chromium and nickel were carried out using flame atomic absorption spectrometry. Selenium was evaluated by spectrophotometry and fluorometry. The daily intake of chromium, nickel, and selenium was found to be 60 μg–90 μg, 124 μg–166 μg, and 54 μg–99 μg, respectively.
Screening for peptides from fish and cheese inhibitory to prolyl endopeptidase
Authors: Sørensen Raymond , Kildal Elisabeth , Stepaniak Leszek , Pripp Are Hugo , Sørhaug Terje
Published: February 2004

Peptides from hydrolysates of fish proteins and from cheeses were analysed for inhibition of prolyl endopeptidase (PE) isolated from porcine muscle. Muscles of cod, salmon, and trout were homogenised and incubated at pH 4.0 with pepsin and then at pH 7.5 with trypsin to obtain fish protein hydrolysates. Homogenates were incubated without exogenous enzymes at pH 4.0 and 7.5 to obtain fish protein autolysates. Water‐soluble extracts from “rakfisk” (a Norwegian fermented/autolysed trout muscle dish) and water‐soluble extracts from Cheddar, Norvegia, Jarlsberg, and Blue cheese were also prepared. Peptides in the supernatants obtained after heat‐treatment of fish hydrolysates, autolysates and water‐soluble extracts of rakfisk and cheeses at 95°C for 15 min were analysed for inhibition of PE. Inhibition was also measured in peptide fractions separated by reversed‐phase high‐performance chromatography and by gel permeation chromatography. The peptide fractions from fish hydrolysates, fish autolysates, and water‐soluble extracts of cheeses inhibited PE in hydrolysing Z‐Gly‐Pro‐amido‐methylcoumarin. Inhibition by peptides from rakfisk was negligible. Pepsin + trypsin hydrolysates from the three fish species contained PE inhibitory peptides with a broad range of apparent hydrophobicity and apparent molecular mass. Autolysates from muscles of the 3 fish species contained narrow peptide peaks of different molecular mass and different apparent hydrophobicity with strong PE inhibitory activity. The content of hydrophilic inhibitory peptides was lower in cheeses than in pepsin + trypsin hydrolysates of fish muscle.
Effects of drying process on antioxidant activity of purple carrots
Authors: Uyan Seda Ersus , Baysal Taner , Yurdagel Ünal , El Sedef Nehir
Published: February 2004

Purple carrot was analysed for its antioxidant activity by measuring its scavenging effect on 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical. The amount of purple carrot necessary to decrease by 50% the initial DPPH concentration (EC50) was found 30.23 ± 5.17 (mg sample /mg DPPH). Effects of the dehydration process on the antioxidant activity of purple carrots were also determined after dehydration by using tray drier and microwave + tray drier combination. Purple carrots were cleaned, washed, sorted, sliced, and blanched in water at 98 ± 1°C for 2 min. Then half of the samples were dehydrated in microwave (45 min) and tray drier (105 min) combination, and others were dehydrated in tray drier (150 min) until reaching the constant weight. Raw, blanched and dehydrated purple carrots were compared for their antioxidant activity and total anthocyanin contents, color values (L*, a*, b*, C*, H°) and dry matter contents. The antioxidant activity as measured by DPPH, EC50 value ranged from 7.80 to 30.23 of processed and raw carrots where the H° values were changed from –3.68 to –23.96 corresponding to a bluish hue.
Physical evaluation of a maize‐based extruded snack with curry powder
Authors: Christofides Vassilis , Ainsworth Paul , Ìbanoǧlu Senol , Gomes Frances
Published: February 2004

Response surface methodology was used to analyze the effect of screw speed (200–280 rpm), feed moisture (13.0–17.0%, wet basis), and curry powder (6.0–9.0%) on the bulk density, lateral expansion, and firmness of maize‐based extruded snack with curry powder. Regression equations describing the effect of each variable on the responses were obtained. Responses were most affected by changes in feed moisture followed by screw speed and curry powder (p < 0.05). Lateral expansion increased linearly as the amount of curry powder added was increased whereas a quadratic increase was obtained in lateral expansion with decreasing feed moisture. The firmness of samples was increased with an increase in feed moisture. The bulk density of samples was increased with increasing feed moisture and screw speeds. Radial expansion was found to be a better index to measure the physical properties of the extruded product indicated by a higher correlation coefficient.
In vitro availability of minerals of some tropical and citrus fruits as influenced by antinutritional factors
Authors: Malik Inass O. , Babiker Elfadil E. , Yousif Nabila E. , El Tinay Abdullahi H.
Published: February 2004

Four tropical fruits and three citrus fruits were analyzed for moisture, ash, antinutritional factors (phytate, oxalate, and polyphenols) contents, and total and available minerals. Moisture contents ranged from 6.0 to 83.17% for tropical fruits while that of citrus fruits ranged from 88.20 to 89.50%. Ash contents ranged from 2.56 to 4.50% and from 3.83 to 4.83%, for tropical and citrus fruits, respectively. All fruits contained no oxalate while phytate and polyphenols ranged from 48.1 to 134.1 mg/100 g and from 0.115 to 0.34%, respectively. For all fruits major minerals contents ranged from 7.7 to 433.3 while trace ones ranged from 0.116 to 1.91 mg/100 g. In vitro availabilities of major minerals (% of total) varied from 11.1 to 86.2% while for minor ones it ranged from 13 to 72.5%.
Enhanced bactericidal action and masking of allergen structure of soy protein by attachment of chitosan through Maillard‐type protein‐polysaccharide conjugation
Authors: Usui Masakatsu , Tamura Hiroshi , Nakamura Kimiko , Ogawa Tadashi , Muroshita Mayumi , Azakami Hiroyuki , Kanuma Shin , Kato Akio
Published: February 2004

The soy protein‐chitosan conjugate was formed by the Maillard reaction in dry state (relative humidity 65%) at 60°C for 2 weeks to improve the functional properties. The antimicrobial activity of the Maillard‐type soy protein‐chitosan conjugates enhanced 2–3 times that of soy protein‐chitosan mixture. The soy protein‐chitosan conjugate showed excellent emulsifying property with the progress of Maillard‐type conjugation. The allergenicity of soy protein was greatly decreased by the attachment of chitosan through Maillard reaction. The immonoblotting analysis with patient's sera revealed that soy protein‐chitosan conjugate was more effective to mask the allergen structure of soy protein causing from 34 kDa‐protein (Gly m Bd 30K) than soy protein‐galactomannan conjugate. The Western blotting showed that allergen (34 kDa‐protein) was completely masked by soy protein‐chitosan conjugation, while it was not completely masked by soy protein‐galactomannan conjugation.
Adjunct starter properties affect characteristic features of Swiss‐type cheeses
Authors: Weinrichter Brigitte , Sollberger Heinz , Ginzinger Wolfgang , Jaros Doris , Rohm Harald
Published: February 2004

A large number of microorganisms, both starter microorganisms and non‐starter lactic acid bacteria originating from the base milk, or from various contamination sources during cheese manufacture, is associated with cheese ripening and the formation of flavour, texture and aroma. Under controlled conditions, Emmental and Bergkäse, a Gruyère‐type cheese variety, were produced from pasteurised milk with standard starters and defined strains of facultatively heterofermentative lactobacilli (FHL), and partly with addition of a defined mixture of enterococci. Lactobacillus casei subsp. casei and L. rhamnosus (two strains each) were selected with respect to their potential for the utilisation of citric acid and ribose as sole energy source. The FHL developed up to 108 cfu/g within the first weeks of ripening, and viable counts in mature cheeses were 107 cfu/g, independent of the cheese variety. Bergkäse made with addition of L. rhamnosus strains showed a more pronounced proteolysis, resulting in reduced firmness and elasticity values of the cheese body, and FHL strains able to utilise citric acid improved the appearance of the cheeses by increasing the number of small eyes to the desired level. In Emmental cheese, the citric acid (+) strains reduced the intensity of propionic acid formation as the FHL apparently competed with the propionibacteria, and enterococci disappeared completely during maturation. Although further work is needed the study shows that, depending on the cheese variety, particular properties of FHL adjunct starters significantly affect important quality attributes of the resulting cheeses.
Distinct sequences on 11q13.5 and 11q23–24 are frequently coamplified with MLL in complexly organized 11q amplicons in AML/MDS patients
Authors: Zatkova Andrea , Ullmann Reinhard , Rouillard Jean Marie , Lamb Barbara J. , Kuick Rork , Hanash Sam M. , Schnittger Susanne , Schoch Claudia , Fonatsch Christa , Wimmer Katharina
Published: February 2004

Amplification within chromosome arm 11q involving the mixed‐lineage leukemia gene (MLL) locus is a rare but recurrent aberration in acute myeloid leukemia and myelodysplastic syndrome (AML/MDS). We and others have observed that 11q amplifications in most AML/MDS cases have not been restricted to the chromosomal region surrounding the MLL gene. Therefore, we implemented a strategy to characterize comprehensively 11q amplicons in a series of 13 AML/MDS patients with MLL amplification. Analysis of 4 of the 13 cases by restriction landmark genomic scanning in combination with virtual genome scan and by matrix‐based comparative genomic hybridization demonstrated that the 11q amplicon in these four cases consisted of at least three discontinuous sequences derived from different regions of the long arm of chromosome 11. We defined a maximally 700‐kb sequence around the MLL gene that was amplified in all cases. Apart from the core MLL amplicon, we detected two additional 11q regions that were coamplified. Using fluorescence in situ hybridization (FISH) analysis, we demonstrated that sequences in 11q13.5 and 11q23–24 were amplified in 8 of 13 and 10 of 12 AML/MDS cases, respectively. Both regions harbor a number of potentially oncogenic genes. In all 13 cases, either one or both of these regions were coamplified with the MLL amplicon. Thus, we demonstrated that 11q amplicons in AML/MDS patients display a complex organization and have provided evidence for coamplification of two additional regions on the long arm of chromosome 11 that may harbor candidate target genes. © 2004 Wiley‐Liss, Inc.
Protracted postnatal natural histories in childhood leukemia
Authors: Maia Ana Teresa , Koechling Joachim , Corbett Robin , Metzler Markus , Wiemels Joseph L. , Greaves Mel
Published: February 2004

Studies of monozygotic twins with concordant leukemia and scrutiny of archived neonatal blood by polymerase chain reaction (PCR) indicated that many pediatric leukemias are initiated prenatally by chromosomal translocation followed by a variable postnatal period before diagnosis of disease. The latter is thought to reflect a persistent preleukemic stage and a requirement for secondary genetic events. We sought to examine this further by examination of blood spots in rare cases of MLL fusion‐positive or ETV6/RUNX1 (TEL‐AML1) fusion gene–positive acute leukemia that were diagnosed at ages beyond the normal age range. We present evidence that the duration of the postnatal preleukemic state can occasionally be very protracted in these biological subtypes of pediatric leukemia, and we discuss its biological significance. © 2004 Wiley‐Liss, Inc.
Identification of a novel RAS GTPase‐activating protein (RASGAP) gene at 9q34 as an MLL fusion partner in a patient with de novo acute myeloid leukemia
Authors: von Bergh Anne R. M. , Wijers Pauline M. , Groot Arjan J. , van Zelderen‐Bhola Shama , Falkenburg J. H. Frederik , Kluin Philip M. , Schuuring Ed
Published: February 2004

The t(9;11) has been described in patients with acute myeloid leukemia (AML), and two genes [AF9 (at 9p21) and FBP17 (at 9q34)] have been cloned as fusion partners of the MLL gene. From an AML‐M5 with a t(9;11)(q34;q23), we identified a novel MLL fusion partner, AF9Q34. The AF9Q34 protein shows high homology with nGAP, a RAS GTPase‐activating protein (RASGAP), and contains the highly conserved GRD and FLR motifs characteristic of RASGAPs. Recently, the rat homologue (DAB2IP) also was identified and reported to act as a RASGAP both in vivo and in vitro. RASGAPs negatively regulate the activity of RAS proteins that modulate diverse cellular processes by cycling between an inactive GDP‐bound and an active GTP‐bound state. In addition, the NH2 terminus harbors an amino acid stretch with homology to the pleckstrin homology (PH) domain implicated in regulating the interaction between RAS and the catalytic domain of RASGAP. As a result of the breakpoint in the AF9Q34–MLL fusion protein, this PH domain is disrupted. This suggests that because of the translocation, the normal function of the AF9Q34 gene is aborted. Thus, AF9Q34 encodes a novel RASGAP gene that appears to be deregulated as a result of the translocation. The identification of this RASGAP protein in a novel MLL fusion implies that an indirect RAS‐deregulating mechanism could be involved in leukemic transformation. © 2004 Wiley‐Liss, Inc.
Distinct mechanisms lead to HPRT gene mutations in leukemic cells
Authors: Lin Ying‐Wei , Perkins Jonathan J. , Zhang Zhenhua , Aplan Peter D.
Published: February 2004

Leukemias are considered malignant clonal disorders arising from the accumulation of mutations in hematopoietic cells; the majority of these mutations are thought to be acquired somatically. Measurement of mutation frequency (Mf) at the hypoxanthine phosphoribosyltransferase (HPRT) locus has been developed as a method for estimating genomic instability. We investigated the Mf in 16 leukemic cell lines to determine whether these cell lines showed evidence of genomic instability. Although some leukemic cell lines had markedly elevated Mfs, the Mfs at the HPRT locus in leukemic cell lines were not always higher than those of B‐lymphoblastoid cell lines and T lymphocytes from normal individuals. We were able to identify the HPRT mutation for 159 of 160 individual HPRT mutants. The HPRT mutations were characterized at a molecular level and classified as either gross chromosomal rearrangements (GCRs) or point mutations, such as single‐nucleotide substitutions, insertions, or deletions. With rare exceptions, individual leukemic cell lines showed either point mutations or GCR, but not both. Of note, all the cell lines that primarily showed point mutations are known to be defective in mismatch repair machinery. © 2004 Wiley‐Liss, Inc.
Effect of TERT and ATM on gene expression profiles in human fibroblasts
Authors: Baross Ágnes , Schertzer Mike , Zuyderduyn Scott D. , Jones Steven J. M. , Marra Marco A. , Lansdorp Peter M.
Published: February 2004

Telomeres protect chromosomes from degradation, end‐to‐end fusion, and illegitimate recombination. Loss of telomeres may lead to cell death or senescence or may cause genomic instability, leading to tumor formation. Expression of human telomerase reverse transcriptase (TERT) in human fibroblast cells elongates their telomeres and extends their lifespan. Ataxia telangiectasia mutated (ATM) deficiency in A‐T human fibroblasts results in accelerated telomere shortening, abnormal cell‐cycle response to DNA damage, and early senescence. Gene expression profiling was performed by serial analysis of gene expression (SAGE) on BJ normal human skin fibroblasts, A‐T cells, and BJ and A‐T cells transduced with TERT cDNA and expressing telomerase activity. In the four SAGE libraries, 36,921 unique SAGE tags were detected. Pairwise comparisons between the libraries showed differential expression levels of 1%–8% of the tags. Transcripts affected by both TERT and ATM were identified according to expression patterns, making them good candidates for further studies of pathways affected by both TERT and ATM. These include MT2A, P4HB, LGALS1, CFL1, LDHA, S100A10, EIF3S8, RANBP9, and SEC63. These genes are involved in apoptosis or processes related to cell growth, and most have been found to be deregulated in cancer. Our results have provided further insight into the roles of TERT and ATM by identifying genes likely to be involved in their function. Supplementary material for this article can be found on the Genes, Chromosomes and Cancer website at http://www.interscience.wiley.com/jpages/1045‐2257/suppmat/index.html. © 2004 Wiley‐Liss, Inc.
Homozygous deletions within the 11q13 cervical cancer tumor‐suppressor locus in radiation‐induced, neoplastically transformed human hybrid cells
Authors: Mendonca Marc S. , Farrington Daphne L. , Mayhugh Brendan M. , Qin Yan , Temples Toni , Comerford Kathleen , Chakrabarti Rita , Zainabadi Kayvan , Redpath J. Leslie , Stanbridge Eric J. , Srivatsan Eri S.
Published: February 2004

Studies on nontumorigenic and tumorigenic human cell hybrids derived from the fusion of HeLa (a cervical cancer cell line) with GM00077 (a normal skin fibroblast cell line) have demonstrated “functional” tumor‐suppressor activity on chromosome 11. It has been shown that several of the neoplastically transformed radiation‐induced hybrid cells called GIMs (gamma ray induced mutants), isolated from the nontumorigenic CGL1 cells, have lost one copy of the fibroblast chromosome 11. We hypothesized, therefore, that the remaining copy of the gene might be mutated in the cytogenetically intact copy of fibroblast chromosome 11. Because a cervical cancer tumor suppressor locus has been localized to chromosome band 11q13, we performed deletion‐mapping analysis of eight different GIMs using a total of 32 different polymorphic and microsatellite markers on the long arm (q arm) of chromosome 11. Four irradiated, nontumorigenic hybrid cell lines, called CONs, were also analyzed. Allelic deletion was ascertained by the loss of a fibroblast allele in the hybrid cell lines. The analysis confirmed the loss of a fibroblast chromosome 11 in five of the GIMs. Further, homozygous deletion (complete loss) of chromosome band 11q13 band sequences, including that of D11S913, was observed in two of the GIMs. Detailed mapping with genomic sequences localized the homozygous deletion to a 5.7‐kb interval between EST AW167735 and EST F05086. Southern blot hybridization using genomic DNA probes from the D11S913 locus confirmed the existence of homozygous deletion in the two GIM cell lines. Additionally, PCR analysis showed a reduction in signal intensity for a marker mapped 31 kb centromeric of D11S913 in four other GIMs. Finally, Northern blot hybridization with the genomic probes revealed the presence of a novel >15‐kb transcript in six of the GIMs. These transcripts were not observed in the nontumorigenic hybrid cell lines. Because the chromosome 11q13 band deletions in the tumorigenic hybrid cell lines overlapped with the minimal deletion in cervical cancer, the data suggest that the same gene may be involved in the development of cervical cancer and in radiation‐induced carcinogenesis. We propose that a gene localized in proximity to the homozygous deletion is the candidate tumor‐suppressor gene. © 2004 Wiley‐Liss, Inc.
Amplification of the TOP2A gene does not predict high levels of topoisomerase II alpha protein in human breast tumor samples
Authors: Mueller Rosemary E. , Parkes Robert K. , Andrulis Irene , O'Malley Frances P.
Published: February 2004

Recent clinical trials have suggested that patients whose breast tumors overexpress HER2 may derive particular benefit from anthracycline‐containing chemotherapy compared to that without anthracycline. It has been proposed that the HER2 gene amplification reported in these tumors might mask an underlying TOP2A gene amplification that occurs frequently and concurrently with HER2 amplification. Topoisomerase II alpha, encoded by TOP2A, is a direct molecular target of anthracycline drug action and is potentially useful as a predictive marker of response to anthracycline therapy for breast cancer. In this study, we examined whether TOP2A gene amplification is an appropriate marker for identifying breast tumors expressing high levels of topoisomerase II alpha. We determined topoisomerase II alpha protein expression by immunohistochemistry in 81 human breast tumors in relation to HER2 and TOP2A gene copy numbers analyzed by fluorescence in situ hybridization, histologic grade, cell proliferation fraction measured by MIB‐1 expression, and HER2 protein expression determined by immunohistochemistry. The results showed no correlation between TOP2A gene copy number and topoisomerase II alpha protein expression levels in breast tumors, in contrast to the analogous situation for HER2 gene amplification and HER2 immunohistochemistry. Our results suggest that TOP2A gene amplification in breast tumors does not predict high expression of topoisomerase II alpha protein. © 2004 Wiley‐Liss, Inc.
Method for making selective lesions of the hippocampus in macaque monkeys using NMDA and a longitudinal surgical approach
Authors: Hampton Robert R. , Buckmaster Cindy A. , Anuszkiewicz‐Lundgren Dawn , Murray Elisabeth A.
Published: February 2004

We describe a method for making selective lesions of the hippocampus in macaque monkeys, using a magnetic resonance imaging (MRI)‐guided stereotaxic approach in which the excitotoxin N‐methyl‐D‐aspartic acid (NMDA) is injected at intervals along a single needle track that extends longitudinally through the rostrocaudal extent of the hippocampus. Procedures were conducted on six rhesus monkeys (Macaca mulatta) and were assessed with either in vivo MRI (n = 3) or postmortem microscopic examination of the tissue after standard histological processing of the brains (n = 3). Based on our extensive experience with the standard stereotaxic procedure in which ibotenic acid (IBO) is injected via the dorsal approach, we report that the new method provides a viable and potentially advantageous alternative to the standard procedure. First, the longitudinal approach combined with N‐methyl‐D‐aspartic acid (NMDA) injections increases the reliability and efficacy of hippocampal excitotoxic lesions, probably by limiting the leakage of injectant into the ventricles. Second, the present procedure led to more rapid postoperative recovery compared with that after the standard procedure. Third, because the new method requires fewer needle penetrations than the standard method, it most likely reduces the chances of infarction in extrahippocampal tissue. Finally, the new surgical approach may provide a mechanism for infusing agents into the hippocampus from a single cannula. Published 2003 Wiley‐Liss, Inc.
Expression of different isoforms of protein kinase C in the rat hippocampus after pilocarpine‐induced status epilepticus with special reference to CA1 area and the dentate gyrus
Authors: Tang F.R. , Lee W.L. , Gao H. , Chen Y. , Loh Y.T. , Chia S.C.
Published: February 2004

At 4 h during pilocarpine‐induced status epilepticus (DPISE) in rat, protein kinase C (PKC)β1, PKCβ2, and PKCγ were induced at the border between the stratum oriens and alveus (O/A border) of CA1 in the hippocampus. Induced PKCγ was colocalized with metabotropic glutamate receptor α (mGluRα). By intracerebroventricular injection of mGluR1α antagonists, (RS)‐1‐aminoindan‐1,5‐dicarboxylic acid (AIDA), PKCβ1, PKCβ2, and PKCγ immunoreactive products decreased dramatically; however, intracerebroventricular injection of saline did not change the expression of PKCβ1, PKCβ2, and PKCγ, suggesting that these three PKC isoforms might be involved in mGluR1α‐related excitoneurotoxicity. One day after pilocarpine‐induced status epilepticus (APISE), PKCδ was induced in microglial cells. At this time point, both PKCγ and PKCϵ immunopositive products decreased in the inner molecular layer of upper blade of the stratum granulosum. At 7–31 days APISE, induced PKCβ1, PKCδ, PKCη, and PKCζ positive astrocytes were demonstrated in all parts of hippocampus, suggesting that they may be involved in gliosis. By this time, both PKCγ and PKCϵ immunopositive products in the inner molecular layer had almost disappeared, suggesting that they may be involved in the inhibition of granule cells by controlling neurotransmitter release presynaptically in the dentate gyrus of normal rats. © 2003 Wiley‐Liss, Inc.
Excitotoxic lesions of the pre‐ and parasubiculum disrupt the place fields of hippocampal pyramidal cells
Authors: Liu Ping , Jarrard Leonard E. , Bilkey David K.
Published: February 2004

To determine what influence the pre‐ and parasubiculum regions of the hippocampal formation have on neural representations within the dorsal hippocampus, single‐unit recordings were made as rats with bilateral ibotenic acid lesions centered on the former regions (n = 4) or control surgeries (n = 3) foraged freely. Spatial firing specificity was measured using an information content procedure. Cells from lesioned animals (n = 57) provided significantly less spatial information than cells from control animals (n = 44). Whereas some degree of location‐related activity (place fields) was observed in 98% of neurons recorded from control animals, it was observed in only 65% of the neurons from lesioned animals. The spatial resolution of the intact place fields appeared to be compromised in lesioned animals as a result of their having a higher firing rate outside the place field. These findings indicate that the pre‐ and parasubiculum regions have a major role in maintaining the specificity of the place field firing of hippocampal pyramidal cells. Since previous data indicate that these lesioned animals displayed delay‐dependent deficits in spatial tasks, these findings also suggest that a disruption in place field activity may be a causal factor in this spatial memory deficit. © 2003 Wiley‐Liss, Inc.
Neural network‐based prediction of transmembrane β‐strand segments in outer membrane proteins
Authors: Gromiha M. Michael , Ahmad Shandar , Suwa Makiko
Published: February 2004

Prediction of transmembrane β‐strands in outer membrane proteins (OMP) is one of the important problems in computational chemistry and biology. In this work, we propose a method based on neural networks for identifying the membrane‐spanning β‐strands. We introduce the concept of “residue probability” for assigning residues in transmembrane β‐strand segments. The performance of our method is evaluated with single‐residue accuracy, correlation, specificity, and sensitivity. Our predicted segments show a good agreement with experimental observations with an accuracy level of 73% solely from amino acid sequence information. Further, the predictive power of N‐ and C‐terminal residues in each segments, number of segments in each protein, and the influence of cutoff probability for identifying membrane‐spanning β‐strands will be discussed. We have developed a Web server for predicting the transmembrane β‐strands from the amino acid sequence, and the prediction results are available at http://psfs.cbrc.jp/tmbeta‐net/. © 2004 Wiley Periodicals, Inc. J Comput Chem 25: 762–767, 2004
Enthalpies of formation from B3LYP calculations
Authors: Winget Paul , Clark Timothy
Published: February 2004

We have calculated the geometries, energies, and normal vibrations of 845 compounds containing the elements H, C, N, O, F, Al, Si, P, S, and Cl using hybrid density functional theory in order to investigate the accuracy of atom‐additive schemes for predicting enthalpies of formation at 298 K. The results give a more realistic estimate of the accuracy of density functional calculations than some overoptimistic earlier correlations. We have also calculated atom‐additive schemes for the zero‐point energies and enthalpic corrections to the energies. Remarkably, it is not important to include the vibrational or rotational contributions, which can be estimated well within a purely Born‐Oppenheimer regression model. © 2004 Wiley Periodicals, Inc. J Comput Chem 25: 725–733, 2004
Performance of the Harris functional for extended basis sets at the Hartree–Fock and density functional levels
Authors: Cullen John
Published: February 2004

The Harris functional is a noniterative variational procedure that uses an input charge density to produce an energy that is surprisingly accurate compared to the converged Kohn–Sham self‐consistent result. We adapted and generalized this functional for the Hartree–Fock closed‐ and open‐shell cases as well as examined its use for hybrid density functional methods such as B3LYP. Analysis of extended basis set calculations shows that at the B3LYP level an input density formed from a double zeta + polarization orbital basis is accurate enough to reproduce the energy of triple zeta + double polarization + diffuse orbital basis. For large molecules this translates into a computational speed that can be an order of magnitude faster. In the case of Hartree–Fock calculations a “bootstrapping technique” that employs successive applications of the Harris functional can further reduce computational times while retaining sufficient accuracy. © 2004 Wiley Periodicals, Inc. J Comput Chem 25: 637–648, 2004