bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative histological studies on liver of mice exposed to Cr(VI) and Cr(V) compounds
Authors: das Neves R Pires , Santos T Margarida , De Lourdes Pereira M , de Jesus J Pedrosa
Published: August 2002

Chromium toxicity is strongly dependent on its oxidation state. Cr(VI) is carcinogenic and mutagenic, although its in vivo and in vitro toxic effects are related to its intracellular fate. Inside the cells, Cr(VI) is rapidly reduced to stable Cr(III). As Cr(V) and Cr(IV) species have been reported to be formed in the Cr(VI) reduction pathways, Cr(VI)induced damage is thought, at least in part, to arise from these hypervalent species. The study of Cr(VI) reduction mechanisms and the characterization of the effects of each reactive intermediate constitute important steps towards a better understanding of chromium toxicity. The purpose of this work is to enlarge the scope of Cr(VI)induced alterations in mouse to other chromium species. Our studies have led to the in situ preparation of a new Cr(V) complex, [CrV–BT]2–, a stable compound at neutral pH, which mimics Cr(VI) reduction intermediates. The effect of Cr(V) on the histology of mice liver is assessed and compared with similar Cr(VI) assays. Liver toxicity was examined after single administrations of Cr(VI) or [CrV–BT]2– to mice. Both compounds produced reversible hepatic damage in a time-dependent manner. However, Cr(V) toxic effects have proved to be more rapid than with Cr(VI), permitting the role of Cr(VI) intermediates formed during intracellular chromium reduction to be highlighted.
Aminoguanidine, an inducible nitric oxide synthase inhibitor, plus N-acetylcysteine treatment reduce the lipopolysaccharideaugmented hepatotoxicity in rats with cirrhosis
Authors: Dogru-Abbasoglu S , Balkan J , Kanbaglõ Ö , Cevikbas U , Aykac-Toker G , Uysal M
Published: August 2002

Hepatic cirrhosis is produced in rats by administration of thioacetamide (TAA) (0.3 g/L tap water for a period of three months). This treatment caused an increase in oxidative stress in the liver. Lipopolysaccharide (LPS) administration (5 mg/kg) to rats with cirrhosis was observed to increase hepatotoxicity as well as oxidative stress according to biochemical and histopathological findings. However, aminoguanidine (AG), an inducible nitric oxide synthase (iNOS) inhibitor, plus N-acetylcysteine (NAC) treatment reduced the LPS-augmented hepatotoxicity in rats with cirrhosis without making any changes in oxidative stress in the liver.
Comments: implications of hormesis for industrial hygienists
Authors: Brophy M O
Published: August 2002

Quantitative health risk assessment is based on extrapolating from the high-dose end of the dose–response curve to points close to the origin or the threshold where the dose levels are closer to the lower environmental or occupational exposures. Hormesis is demonstrated in chronic toxicological studies where the animals treated at the lowest experimental dose appear to be healthier than the controls, as evidenced by longer life spans, less disease and/or increased body weight. If the occupational exposure limit (OEL) or environmental exposure limit (EEL) is in the range of the hormetic effect, or lower than the hormetic effect, then a case could be made that exposure at the OEL or EEL is `safe.’ This idea is controversial because it challenges some of the basic assumptions of quantitative health risk assessment as it has been practiced during the past 50 years. De-emphasis of the dose–response curve in determining OELs and EELs will occur not because of hormesis, but because the emerging sciences of genomics and proteomics will shift the focus from statistical methods to individuals as genetic and protein engineering becomes more sophisticated and powerful.
Comments on the Jayjock et al. paper
Authors: Rozman K K , Doull J
Published: August 2002

Establishing hormesis as an evolution-based biological phenomenon requires a broad discussion of its implications for currently used risk paradigms. The Jayjock et al.papers provide an industrial hygienist’s perspective and, as such, represent a valuable contribution to this discussion. Our comments outline a toxicologist’s view on the limits and practicability of the Jayjock et al. suggestions.

The arguments are primarily based on the shape of dose and time responses and associated variabilities and uncertainties. Human & Experimental Toxicology (2002) 21,405–406.
An Exploration of the Relationship Between Patient Autonomy and Patient Advocacy: implications for nursing practice
Authors: Hyland Deirdre
Published: August 2002

The purpose of this article is to examine whether patient/client autonomy is always compatible with the nurse’s role of advocacy. The author looks separately at the concepts of autonomy and advocacy, and considers them in relation to the reality of clinical practice from professional, ethical and legal perspectives.

Considerable ambiguity is found regarding the legitimacy of claims of a unique function for nurses to act as patient advocates. To act as an advocate may put nurses at personal and professional risk. It may also be deemed arrogant and insulting to other health care professionals. Patient autonomy can be seen as a subcategory of the right of every individual to self-determination, and as such is protected by law. However, it is questionable whether the traditionally paternalistic approach to health care provision truly respects the autonomous rights of each patient.

The author considers examples and cases from the literature that resulted in professional and/or personal difficulties for the nurses involved, and also reflects on an incident from her own practice where a positive outcome was achieved that demonstrated compatibility between the concepts under consideration.
Decision Making in Health Care: limitations of the substituted judgement principle
Authors: Bailey Susan
Published: August 2002

The substituted judgement principle is often recommended as a means of promoting the self-determination of an incompetent individual when proxy decision makers are faced with having to make decisions about health care. This article represents a critical ethical analysis of this decision-making principle and describes practical impediments that serve to undermine its fundamental purpose. These impediments predominantly stem from the informality associated with the application of the substituted judgement principle. It is recommended that the principles upon which decisions are made about health care for another person should be transparent to all those involved in the process. Furthermore, the substituted judgement principle requires greater rigour in its practical application than currently tends to be the case. It may be that this principle should be subsumed as a component of advance directives in order that it fulfils its aim of serving to respect the self-determination of incompetent individuals.
Examining Ethics in Practice: health service professionals’ evaluations of in-hospital ethics seminars
Authors: Alderson Priscilla , Farsides Bobbie , Williams Clare
Published: August 2002

This article reviews practitioners’ evaluations of in-hospital ethics seminars. A qualitative study included 11 innovative in-hospital ethics seminars, preceded and followed by interviews with most participants. The settings were obstetric, neonatal and haematology units in a teaching hospital and a district general hospital in England. Fifty-six health service staff in obstetric, neonatal, haematology, and related community and management services participated; 12 attended two seminars, giving a total of 68 attendances and 59 follow-up evaluation interviews. The 11 seminars facilitated by an ethicist addressed the key local concerns of staff about the social and ethical consequences of advances in genetics and their impact on professional policies and practice. Seminar agendas were drawn from prior interviews with 70 staff members.

During evaluation interviews, participants commented on general aspects that they had enjoyed, how the sessions could be improved, timing, the mix of participants, the quality of the facilitation, whether sessions should be more challenging, after-effects of sessions, and interest in attending seminars and contacting the ethicist in future. Participants valued the increased interprofessional understanding and coherent discussion of many pressing issues that addressed important though seldom discussed ethical questions. The seminars worked well in the different hospitals and specialties.
Older Persons’ Ethical Problems Involving Their Health
Authors: Cameron Miriam E
Published: August 2002

Although older persons (aged 65 years and older) experience stressful ethical problems involving their health, research is lacking about this phenomenon. The purpose of this study was to describe and examine the content and basic nature of older persons’ ethical problems concerning their health. The conceptual framework and method combined ethical enquiry and phenomenology. The participants were 18 older persons and 12 of their children or grandchildren (for contextual understanding). The 19 women and 11 men, 73% of whom were Caucasian, described 184 ethical problems, from which emerged 10 content categories. The basic nature of the ethical problems consisted of conflict, resolution and rationale. The results could assist health professionals to promote older persons’ ethical decision making, quality of life, and good death.
The use of vectors for defining the three-dimensional texture and asymmetric directionality of turned specimens
Authors: Burrows J , Griffiths B , Scott P
Published: August 2002

The authors consider that existing two-dimensional surface parameters (calculated using stylus profilometry techniques) are inadequate for describing engineering surfaces when the three-dimensional nature of an engineering surface also affects the functional performance. This paper proposes a definition of three-dimensional surface texture in terms of lay, directionality and anisotropy. The authors propose a novel technique developed from image processing technology, which uses vectors, to describe these three-dimensional surface properties. The proposed technique is validated via analysis of a series of turned surfaces.
An evolutionary approach to complex job-shop and flexible manufacturing system scheduling
Authors: Rossi A , Dini G
Published: August 2002

This paper presents a genetic algorithm for generalized job-shop problem solving. The generalization includes feeding times, sequences of set-up dependent operations and jobs with different routings among workcentres including ‘multi-identical’ machines. A formulation as an optimization problem with an original chromosome coding and tailored genetic operators are proposed. The algorithm has been tested with benchmarks given in the literature, and bounds for the minimum completion time are reported in order to evaluate the performance in both generalized job-shop and flexible manufacturing system (FMS) scheduling.
Minimizing the number of tool switches on a flexible machine: An experimental study
Authors: Shirazi R , Frizelle G D M
Published: August 2002

Tool switching heuristics determine the sequence for the parts and the associated sequence for the tools for the tool magazine so that the total number of tool switches is minimized. This paper examines whether there is a need for tool switching heuristics in industry and assesses the validity and usefulness of current approaches. Studies that have tested the performance of tool switching heuristics are examined and their flaws highlighted. The research then goes on to test the heuristics on a much broader range of problems using a rigorous framework. The results reveal which heuristics perform more robustly than others and link the performance of different heuristics to different problem types.
The effects of temper rolling conditions on the spectral signatures of sticker wrench faults in batch annealed steel strip
Authors: Stuckey C , Moore J , Brandon J A
Published: August 2002

In a previous study, the authors related the incidence of sticker wrench faults to a characteristic acoustic emission signature. In the present paper, the effects of mill control variables on the incidence of sticker wrenching are investigated. The study provides an advance in the scientific understanding of the origins of sticker wrench defects and has considerable commercial potential.
The effect of ultrasound in micro electro discharge machining on surface roughness
Authors: Yeo S H , Goh K M
Published: August 2002

In this paper, an efficient micromachining process, which combines micro electro discharge machining (MEDM) with ultrasonic vibration, is proposed to improve the surface roughness of micromould inserts. The introduction of ultrasound is aimed at improving the surface quality by means of the accelerated expulsion of debris out of the small gap between the electrode and the workpiece. Experimental results show that the surface roughness of the machined workpiece is improved.
A mechanical model for predicting critical thrust forces in drilling composite laminates
Authors: Zhang L-B , Wang L-J , Liu X-Y
Published: August 2002

Among the various forms of material damage, delamination due to drilling is one of the major concerns in machining a composite laminate. The thrust force has been cited as the primary cause of the delamination. The analysis for multidirectional composite laminates is based on linear elastic fracture mechanics (LEFM), classical bending plate theory and the mechanics of composites. This paper presents a general closed-form mechanical model for predicting the critical thrust force at which delamination is initiated at different ply locations. Good correlation is observed between the model and the experimental results.
Photo-oxidative Stability and its Correlation with Semi-empirical MO Calculations of Various Tetraazaporphyrin Derivatives in Solution
Authors: SCHNURPFEIL GüNTER , SOBBI ABDOL KHEZER , SPILLER WOLFGANG , KLIESCH HOLGER , WÖHRLE DIETER
Published: September 2002

The photo-oxidative stability of various annelated and substituted tetraazaporphyrin derivatives were investigated in N , N -dimethylformamide by irradiation in the presence of air. First-order rate constants were calculated. In addition, the positions of the HOMO and LUMO energy levels of the compounds were calculated using a commercially available program. A linear correlation between the experimental values of the rate constants and the theoretical values of the HOMO position exists. The method described allows one to predict the photo-oxidative stability by calculating their HOMO levels, which is very important for the use of macrocyclic metal complexes in photo-oxidation reactions in solution. From the calculated triplet energies it is considered that the macrocyclic metal complexes can convert by photoinduced energy transfer triplet oxygen to singlet oxygen. Experimentally, tetraazaporphyrin derivatives show high quantum yields of singlet oxygen formation under irradiation. No correlations of the quantum yields with the position of the HOMOs or with the rate constants of decomposition was observed.
The Alpha Substitution Effect on Phthalocyanine Aggregation
Authors: GEORGE ROBERT D. , SNOW ARTHUR W. , SHIRK JAMES S. , BARGER W. R.
Published: September 2002

The dimerization and tendency to form higher aggregates of two isomeric metal-free phthalocyanine compounds with tetracumylphenoxy peripheral substitution at the alpha (1 or 4, 5 or 8, 9 or 12, 13 or 16) and beta (2 or 3, 6 or 7, 10 or 11, 14 or 15) positions has been analysed by spectroscopic measurements. The dimerization constants in chloroform solution are 1.3 × 101 M −1 and 7.0 × 103 M −1 respectively. At concentrations greater than 10−3 M , the beta phthalocyanine isomer forms a spectroscopically resolvable higher aggregate. Q-band spectra of the dimer of each isomer and of the aggregate of the beta isomer in chloroform solution were generated. Comparison of these spectra with the corresponding thin film spectra of each isomer indicates that the stronger tendency toward aggregation of the beta isomer extends into the solid state. The difference in aggregating tendency of the two isomers was attributed to a steric constraint of the alpha isomer that restricts conformational freedom and, consequently, hinders formation of dimer and higher order complexes.
Dielectric Properties of Iron Phthalocyanine Compounds
Authors: BIJWE JAYASHREE , PHOUGAT NEELAM
Published: September 2002

Monomeric and polymeric iron phthalocyanine compounds were synthesized and their dielectric properties were measured in the frequency range from 100 Hz to 10 MHz between 25 and 200 °C. The dielectric constant and dielectric loss showed strong frequency and temperature dependences. Interestingly, large dielectric constants were observed around 100 °C for both monomers and polymers. A dielectric constant as high as 5000 at 110 Hz was observed for the iron phthalocyanine polymer. The origin of the large dielectric constant in metallophthalocyanines is discussed.
Synthesis, characterization and electrochemistry of bismuth porphyrins: X-ray crystal structure of (OEP)Bi(SO3CF3)
Authors: MICHAUDET LYDIE , FASSEUR DOMINIQUE , GUILARD ROGER , OU ZHONGPING , KADISH KARL M. , DAHAOUI SLIMANE , LECOMTE CLAUDE
Published: September 2002

The metalation of several free base porphyrins by the bismuth salts Bi(NO3)3 and Bi(SO3CF3)3 in DMF or pyridine is described. The resulting stable Bi(III) porphyrin complexes are characterized by electrochemistry, 1H NMR and UV-vis spectroscopy. The structure of ( OEP ) Bi ( SO 3 CF 3) was also determined by single-crystal X-ray diffraction and shows that ( OEP ) Bi ( SO 3 CF 3) exists as a dimer which is stabilized by electrostatic interactions in which the two [(OEP)Bi]+ cations are linked via oxygen atoms of two symmetrically related [Formula: see text] anions, leading to a heptacoordinated bismuth center. Electrochemical oxidation of ( OEP ) Bi ( SO 3 CF 3) and ( T p TP ) Bi ( SO3CF3 ) shows that only the porphyrin macrocycles are oxidized.
International direct marketing on the internet: Do internet users form a global segment?
Authors: Mehta Raj , Grewal Rajdeep , Sivadas Eugene
Published: September 2002

Much of the international marketing literature has focused on issues relevant to large multinational corporations. Many of these results are not useful to direct marketers. The international marketing literature has also ignored the implications of information technology (IT) for international marketing practice. In this article, we suggest that IT can be used to identify a global segment to which goods and services can be marketed direct. We demonstrate that this global segment meets all criteria for an effective segment: accessible, measurable, substantial, differentiable, and actionable.
Oligooxyethylene liquid phthalocyanines
Authors: SNOW ARTHUR W. , SHIRK JAMES S. , PONG RICHARD G. S.
Published: September 2002

A series of methyl-terminated oligooxyethylene ( CH 3( OCH 2 CH 2)n O , n = 8.8)-substituted phthalocyanines with peripheral substitution at four β positions, at four α positions and at the eight α positions was synthesized and structurally characterized. These compounds are isotropic liquids above 10 °C. Non-linear optical properties of the tetra-α- and tetra-β-substituted compounds were examined. Both are reverse saturable absorbers in the visible region of the spectrum, but the tetra-α-substituted compound has the larger non-linear absorption coefficient and can be a useful optical limiter in cases where a non-volatile liquid is desirable.
The vibronic fine structure of the emission spectrum of silicon phthalocyanine
Authors: BRAUN DIETER , TITECA BRUNO C. , CEULEMANS ARNOUT
Published: September 2002

Sharp line emission spectra of the silicon phthalocyanine complex ((n- C 6 H 13)3 SiO )2 SiPc at low temperatures are resolved in multiple sites, and the vibronic fine structure of single-site emissions is identified. DFT methods are used to calculate the complete set of normal modes of the Cl 2 SiPc analogue. Geometry optimization of the excited state further yields the Franck–Condon and Jahn–Teller distortions in the emitting state. These results are combined to obtain theoretical Huang–Rhys factors for the active modes, which compare favourably with the experimental spectrum. The dominant satellites are a 675 cm−1 mode, which is identified as a totally symmetric bending of the four pyrrole rings, and a 1552 cm−1 mode, which is assigned to an antisymmetric stretching of the aza-nitrogens with tetragonal b 1 g symmetry.
Pricing U.S. North Atlantic bluefin tuna and implications for management
Authors: Carroll Michael T. , Anderson James L. , Martínez‐Garmendia Josué
Published: September 2002

Bluefin tuna is regarded as a high‐quality product in the Japanese market and is characterized by an unusual marketing system by seafood industry standards. Each fish is individually inspected for various quality attributes before being flown to Japan for the fresh tuna market. The first objective of this study is to formally evaluate the degree to which the price of U.S. fresh bluefin tuna is determined by quality attributes of each fish, rather than by just the quantity supplied. This is accomplished using a Hedonic model. The results support the hypothesis that the fresh bluefin tuna price is, in fact, significantly influenced by the quality attributes of the fish, including the freshness, fat content, color, and shape. Interesting implications for public management of this highly valued resource arise from the results. [Econ‐Lit citation: L150, L190, L660] © 2001 John Wiley & Sons, Inc.
Variations of ferritin levels over a period of 15 years as a compliance chelation index in thalassemic patients
Authors: Kattamis Antonios , Dinopoulos Argyris , Ladis Vassilios , Berdousi Helen , Kattamis Christos
Published: September 2002

We studied the changing pattern of the distribution of ferritin levels in 430 regularly‐transfused patients with thalassemia in an attempt to evaluate compliance of chelation with deferoxamine. The study covered 15 years and was divided in three periods: 1981 – 1985, 1986 – 1990, and 1991 – 1995. The patients were stratified in age‐groups. The mean ferritin levels of each period were calculated for each patient individually. The study showed that: (i) When all the patients were compared as a group, there was a significant decrease in mean ferritin between 1981 – 1985 and 1991 – 1995, despite a significant change in the patients’ mean age; (ii) When patients of same age were compared between periods, there was a decrease in mean ferritin between 1981 – 1985 and 1991 – 1995, as well as a decrease in the proportion of patients with ferritin >4000 μg/L, with a parallel increase in the proportion of patients who had ferritin <2000 μg/L; (iii) When the same patients were followed longitudinally, they showed a decrease in their ferritin levels in all age groups with the exception of the late adolescence period. The decrease in iron overload observed in patients on close follow up implies that compliance with chelation therapy has improved with time and therefore, a favourable influence in survival could be expected. Am. J. Hematol. 68:221–224, 2001. © 2001 Wiley‐Liss, Inc.
β‐enolase deficiency, a new metabolic myopathy of distal glycolysis
Authors: Comi Giacomo P. , Fortunato Francesco , Lucchiari Sabrina , Bordoni Andreina , Prelle Alessandro , Jann Stefano , Keller Angélica , Ciscato Patrizia , Galbiati Sara , Chiveri Luca , Torrente Yvan , Scarlato Guglielmo , Bresolin Nereo
Published: September 2002

A severe muscle enolase deficiency, with 5% of residual activity, was detected in a 47‐year‐old man affected with exercise intolerance and myalgias. No rise of serum lactate was observed with the ischemic forearm exercise. Ultrastructural analysis showed focal sarcoplasmic accumulation of glycogen β particles. The enzyme enolase catalyzes the interconversion of 2‐phosphoglycerate and phosphoenolpyruvate. In adult human muscle, over 90% of enolase activity is accounted for by the β‐enolase subunit, the protein product of the ENO3 gene. The β‐enolase protein was dramatically reduced in the muscle of our patient, by both immunohistochemistry and immunoblotting, while α‐enolase was normally represented. The ENO3 gene of our patient carries two heterozygous missense mutations affecting highly conserved amino acid residues: a G467A transition changing a glycine residue at position 156 to aspartate, in close proximity to the catalytic site, and a G1121A transition changing a glycine to glutamate at position 374. These mutations were probably inherited as autosomal recessive traits since the mother was heterozygous for the G467A and a sister was heterozygous for the G1121A transition. Our data suggest that ENO3 mutations result in decreased stability of mutant β‐enolase. Muscle β‐enolase deficiency should be considered in the differential diagnosis of metabolic myopathies due to inherited defects of distal glycolysis.
Preparation and characterization of tris(iso‐propyl)stibine complexes of palladium and platinum
Authors: Phadnis Prasad P. , Jain Vimal K. , Varghese Babu
Published: September 2002

Tris(iso‐propyl)stibine complexes of palladium and platinum of the type [MX2(SbiPr3)2] [M, X = Pd, Cl (1a), Pd, Br (1b), Pd, I (1c), Pt, Cl (2)] have been prepared and characterized by elemental analysis, IR and 1H NMR spectral data. The structure of 1a, established by X‐ray structural analysis, revealed that the palladium atom is in a square planar environment with mutually trans SbiPr3 ligands. Copyright © 2001 John Wiley & Sons, Ltd.
Cardiac morphology and blood pressure in the adult zebrafish
Authors: Hu Norman , Yost H. Joseph , Clark Edward B.
Published: September 2002

Zebrafish has become a popular model for the study of cardiovascular development. We performed morphologic analysis on 3 months postfertilization zebrafish hearts (n ≥ 20) with scanning electron microscopy, hematoxylin and eosin staining and Masson's trichrome staining, and morphometric analysis on cell organelles with transmission electron photomicrographs. We measured atrial, ventricular, ventral, and dorsal aortic blood pressures (n ≥ 5) with a servonull system. The atrioventricular orifice was positioned on the dorsomedial side of the anterior ventricle, surmounted by the single‐chambered atrium. The atrioventricular valve was free of tension apparati but supported by papillary bands to prevent retrograde flow. The ventricle was spanned with fine trabeculae perpendicular to the compact layer and perforated with a subepicardial network of coronary arteries, which originated from the efferent branchial arteries by means of the main coronary vessel. Ventricular myocytes were larger than those in the atrium (P < 0.05) with abundant mitochondria close to the sarcolemmal. Sarcoplasmic reticulum was sparse in zebrafish ventricle. Bulbus arteriosus was located anterior to the ventricle, and functioned as an elastic reservoir to absorb the rapid rise of pressure during ventricular contraction. The dense matrix of collagen interspersed across the entire bulbus arteriosus exemplified the characteristics of vasculature smooth muscle. There were pressure gradients from atrium to ventricle, and from ventral to dorsal aorta, indicating that the valves and the branchial arteries, respectively, were points of resistance to blood flow. These data serve as a framework for structure‐function investigations of the zebrafish cardiovascular system. Anat Rec 264:1–12, 2001. © 2001 Wiley‐Liss, Inc.
Localization of luteinizing‐hormone releasing hormone binding sites in the gastric mucosa of suckling rats
Authors: Gama Patrícia , Alvares Eliana Parisi
Published: September 2002

Luteinizing‐hormone releasing hormone (LHRH) is a hypothalamic and milk‐borne hormone that inhibits the cell proliferation of gastric epithelium in developing rats, although the mechanism of such action is unknown. We investigated the presence of binding sites for LHRH in the stomach of suckling rats after the injection of the hormone. Immunofluorescence at the confocal microscopy level revealed that LHRH binds to gastric cells, being particularly abundant over the gland. Different fluorescent lectins were used to identify gastric cell types and determine which were labeled by the hormone. Colocalization studies in these double‐labeling experiments showed that LHRH staining colocalizes with parietal cells, suggesting the presence of binding sites in these cells. The three‐dimensional (3‐D) reconstruction of isolated parietal cells revealed the localization of the signal, which appears to be in the membrane of the canalicular region. These results suggest that there are binding sites for LHRH in the gastric epithelium, specifically in parietal cells, and they might play a role in the control of cell proliferation during suckling. Anat Rec 264:43–50, 2001. © 2001 Wiley‐Liss, Inc.
A cellular survival switch: poly(ADP‐ribosyl)ation stimulates DNA repair and silences transcription
Authors: Ziegler Mathias , Oei Shiao Li
Published: September 2002

Poly(ADP‐ribosyl)ation is a post‐translational modification occurring in the nucleus. The most abundant and best‐characterized enzyme catalyzing this reaction, poly(ADP‐ribose) polymerase 1 (PARP1), participates in fundamental nuclear events. The enzyme functions as molecular “nick sensor”. It binds with high affinity to DNA single‐strand breaks resulting in the initiation of its catalytic activity. Activated PARP1 promotes base excision repair. In addition, PARP1 modifies several transcription factors and thereby precludes their binding to DNA. We propose that a major function of PARP1 includes the silencing of transcription preventing expression of damaged genes. Concomitant stimulation of DNA repair suggests that PARP1 acts as a switch between transcription and DNA repair. Another PARP‐type enzyme, tankyrase, is involved in the regulation of telomere elongation. Tankyrase modifies a telomere‐associated protein and thereby prevents it masking telomeric repeats providing access of telomerase for telomere elongation. Therefore, poly(ADP‐ribosyl)ation reactions may act as molecular switches in DNA metabolism. BioEssays 23:543–548, 2001. © 2001 John Wiley & Sons, Inc.
Molecular biology and anatomy of Drosophila olfactory associative learning
Authors: Roman Gregg , Davis Ronald L.
Published: September 2002

Most of our current knowledge of olfactory associative learning in Drosophila comes from the behavioral and molecular analysis of mutants that fail to learn. The identities of the genes affected in these mutants implicate new signaling pathways as mediators of associative learning. The expression patterns of these genes provide insight into the neuroanatomical areas that underlie learning. In recent years, there have been great strides in understanding the molecular and neuroanatomical basis for olfaction in insects. It is now clear that much of the association between the conditioned stimuli and the unconditioned stimuli in olfactory learning occurs within mushroom bodies — third order olfactory neurons within the central brain. In this review, we discuss the nature of the behavioral tasks, the molecules, and the neuronal circuits involved in olfactory learning in Drosophila. BioEssays 23:571–581, 2001. © 2001 John Wiley & Sons, Inc.
On‐line size measurement of yeast aggregates using image analysis
Authors: Mas Sandrine , Ghommidh Charles
Published: September 2002

Alcohol fermentation productivity can be strongly improved using a flocculation‐based yeast recycle. However, the efficiency of the biomass retention system depends strongly on the yeast particle size. Accordingly, the monitoring and control of yeast floc diameter are of primary importance. The on‐line measurement of mean floc diameter has been achieved using on‐line image analysis, based on the evaluation of image texture. The texture analysis method consisted in the building of a co‐occurrence matrix from which the so‐called “Energy parameter” was extracted. While image texture is usually used for classification purposes, it has been used here as a quantitative descriptor: a correlation has been found between this statistical image feature and off‐line manual floc‐size determinations. In the floc‐size range investigated (|bu 0.5–4.3 mm), the evaluated mean diameter was in good agreement with the actual particle size, with a determination coefficient equal to 0.980. In contrast with manual measurements, slow and tedious, this method gave the value of the mean particle diameter in real‐time, without sampling. This novel tool has been used to investigate the behavior of yeast aggregates as a function of fermentation conditions. While biomass concentration was kept constant, step increases of the feed rate led to a decrease of the mean floc diameter. Image analysis showed that the particle‐size reduction could occur within a few minutes after modification of the medium dilution rate, demonstrating the disruptive effect of the CO2 efflux. The kinetic of aggregate formation was dependent on the gas‐phase composition. Instead of recycling fermentation gas, sparging the fermentor with nitrogen, to reduce dissolved CO2 concentration, increased the rate of floc‐size growth. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 76: 91–98, 2001.
Direct resolution of (±)‐ephedrine and atropine into their enantiomers by impregnated TLC
Authors: Bhushan R. , Martens J. , Arora Meenakshi
Published: September 2002

Direct resolution of (±)‐ephedrine and atropine into their enantiomers was achieved by normal‐phase thin layer chromatography on silica gel plates impregnated with optically pure L‐tartaric acid and L‐histidine, respectively, as chiral selectors. The mobile phases enabling successful resolution were different combinations of acetonitrile–methanol–water. The spots were detected with iodine vapours and the detection limits were 2 and 6 µg, respectively, in terms of the racemate. The effects of concentration of the impregnating reagent, temperature and pH on resolution have been studied. Copyright © 2001 John Wiley & Sons, Ltd.
First synthesis of the two enantiomers of α‐methyldiphenylalanine [(αMe)Dip] by HPLC resolution
Authors: Royo Soledad , López Pilar , Jiménez Ana I. , Oliveros Laureano , Cativiela Carlos
Published: September 2002

A strategy for the preparation of enantiomerically pure (R)‐ and (S)‐α‐methyldiphenylalanine, constrained phenylalanine analogs, is described. A racemic precursor was prepared in high yield from easily available starting products and subjected to HPLC resolution on a noncommercial chiral stationary phase. More than 600 mg of each enantiomer was isolated in optically pure form by using a 150 × 20 mm ID column containing mixed 10‐undecenoate/3,5‐dimethylphenylcarbamate of cellulose covalently bonded to allylsilica gel and a mixture of n‐hexane/2‐propanol/acetone as the mobile phase. Chirality 14:39–46, 2002. © 2002 Wiley‐Liss, Inc.
Solvent‐free optical resolution of N‐methylamphetamine by distillation after partial diastereoisomeric salt formation
Authors: Kozma Dávid , Fogassy Elemér
Published: September 2002

Solvent‐free optical resolution of N‐methylamphetamine was developed by distillation after partial diastereoisomeric salt formation. From the 18 chiral acids tested by this method, five provide by this method resolution: O,O′‐dibenzoyltartaric acid, O,O′‐di‐p‐toluoyltartaric acid, 6‐methoxy‐α‐methyl‐2‐naphthaleneacetic acid (Naproxen), the cis‐permetrinic acid, and the 2‐phenoxypropionic acid. Among them the O,O′‐dibenzoyltartaric acid in water‐free form provided the more effective resolution. The efficiency of this resolution S = 0.74 is in the range of the industrial‐scale resolutions and not worse than the efficiency achieved by optical resolution via fractional crystallization. Chirality 13:428–430, 2001. © 2001 Wiley‐Liss, Inc.
Chiral recognition of dipeptide methyl esters by an anionic β‐cyclodextrin
Authors: Kano Koji , Hasegawa Hideki , Miyamura Muneki
Published: September 2002

Chiral recognition of dipeptide methyl esters by anionic heptakis[6‐carboxymethylthio‐6‐deoxy]‐β‐cyclodextrin (per‐CO2−‐β‐CD) was studied in D2O at pD 7.0 by means of 1H NMR spectroscopy. The methyl esters of alanylalanine (Ala‐Ala‐OMe), alanylleucine (Ala‐Leu‐OMe), alanyltryptophan (Ala‐Trp‐OMe), glycyltryptophan (Gly‐Trp‐OMe), valyltryptophan (Val‐Trp‐OMe), leucyltryptophan (Leu‐Trp‐OMe), and tryptophylalanine (Trp‐Ala‐OMe) were used as the dipeptides. The binding constant (K) determined from NMR titration increases in the order Ala‐Ala‐OMe < Ala‐Leu‐OMe < Ala‐Trp‐OMe, suggesting that van der Waals interactions between the host and the guest participate in complexation. Coulomb interactions between the protonated dipeptide methyl esters and the anionic host seem to be another attractive force. Per‐CO2−‐β‐CD interacts with the (R,R)‐enantiomers of the dipeptide methyl esters more strongly than the (S,S)‐enantiomers. Such enantioselectivity corresponds to that for α‐amino acid methyl esters such as Leu‐OMe and Trp‐OMe, whose (R)‐enantiomers are the preferable guests. The enantioselectivity is mainly dominated by amino acid residue at the C‐terminal and chirality at the N‐terminal residue plays an assistant role. An asymmetrically twisted shape of the host cavity may be essential for chiral recognition. Chirality 13:474–482, 2001. © 2001 Wiley‐Liss, Inc.
Geochemical evolution of amino acids in dentine of pleistocene bears
Authors: De Torres Trinidad , Ortiz José E. , García María J. , Llamas Juan F. , Canoira Laureano , García De La Morena Miguel A. , Juliá Ramón
Published: September 2002

A linear correlation was established between aspartic acid racemization ratio from cave bear dentine collagen and absolute dating. The high correlation coefficient obtained allowed age calculation through amino acid racemization. Aspartic acid and glutamic acid racemization kinetics have also been explored in dentine from a North American black bear (Ursus americanus Pallas). Three sample sets were prepared for kinetic heating experiments in nitrogen atmosphere: one water soaked, one with a water‐saturated nitrogen atmosphere, and one without any moisture. It was possible to show that the presence of water is a factor controlling amino acid racemization rate. The aspartic acid in a heating experiment at 105°C shows an “apparent kinetics reversal” which can be explained by a progressive hydrolysis of amino acid chains (proteins and polypeptides). Because of the low potential of collagen preservation over long periods of time, the apparent kinetics reversal phenomenon will not affect the dating of old material where no traces of collagen remain. An apparent kinetics reversal was not observed in glutamic acid, which racemizates more slowly. Chirality 13:517–521, 2001. © 2001 Wiley‐Liss, Inc.
Micellar electrokinetic capillary chromatography determination of (+)S and (−)R arotinolol in serum using UV detection and solid phase extraction
Authors: Hefnawy Mohammed M.
Published: September 2002

A method for the simultaneous determination of (+)S and (−)R arotinolol in serum by micellar electrokinetic capillary chromatography is described. Stereoselective resolution of the arotinolol enantiomers was achieved using 5 mM sodium taurocholate in 10 mM sodium dihydrogen phosphate buffer of pH 2.5. A 72‐cm uncoated fused‐silica capillary at a constant voltage of 15 kV was used for the analysis. The analytes of interest were extracted from serum using solid phase extraction. An octadecyl cartridge gave good recoveries in excess of 87% for both (+)S and (−)R arotinolol without any interference. The calibration curves were linear over the range of 50–500 ng ml−1 with (+)S propranolol as the internal standard and the coefficient of determination was greater than 0.999 (n = 3). The limit of quantitation was 50 ng ml−1 for each enantiomer and the detection limit using 1 ml serum and a UV detection set et 220 nm was 25 ng ml−1 (S/N = 2). Precision and accuracy of the method were in the range 0.8–2.7% and 1.2–6.4%, respectively, for (+)S arotinolol and 1.1–3.9% and 2.2–6.5%, respectively, for (−)R arotinolol. Chirality 14:67–71, 2002. © 2002 Wiley‐Liss, Inc.
Colour‐difference evaluation using CRT colours. Part I: Data gathering and testing colour difference formulae
Authors: Cui Guihua , Luo M. Ronnier , Rigg B. , Li Wei
Published: September 2002

A large set of colour discrimination data based upon Cathode Ray Tube (CRT) colours was accumulated. The experiment was carried out to study the effect of changes in viewing parameters on perceived colour differences. It was divided into sixteen phases. Each phase was conducted under a different set of experimental conditions including different sample sizes, backgrounds, frames, widths, and colours of separation between pairs of samples. For each phase, 134 pairs of colours with average 2.7 CIELAB colour difference were studied. The colours closely corresponded to the five colour centers proposed by the CIE. Each pair was assessed by 10 or 20 observers using the gray scale method. The visual results from the present study were also used to test six colour‐difference formulae: CIELAB, CMC, BFD, CIE94, LCD, and CIEDE2000. The latter outperformed the other formulae and is the new CIE colour‐difference equation. The current results were also compared with the other datasets based upon surface colours. The present results are consistent with those obtained for surface colours. © 2001 John Wiley & Sons, Inc. Col Res Appl, 26, 394–402, 2001
The validity of the trans‐theoretical model of behaviour change to investigate motivation to change among child molesters
Authors: Tierney David W. , McCabe Marita P.
Published: September 2002

Motivation for behaviour change is considered a crucial issue in the treatment of sex offenders, including child molesters. However, there has been no systematic investigation of this issue. This paper reviews the validity of the constructs of the Trans‐theoretical Model of Behaviour Change to act as a framework to investigate motivation for behaviour change among child molesters. Constructs within this theory are the Stages of Change, Processes of Change and Decisional Balance. The utility of these constructs to act as a framework to investigate motivation among child molesters is assessed by reviewing their utility as measures of motivation for behaviour change generally, and by reviewing their relevance to child molesters. It is concluded that the constructs of the Trans‐theoretical Model of Behaviour Change are valid measures of motivation and have some general relevance to child molesters. It is therefore concluded that they have some utility to investigate motivation to change among child molesters. Copyright © 2001 John Wiley & Sons, Ltd.
Analysis of Ki‐ras gene mutations associated with DNA diploid, aneuploid, and multiploid colorectal carcinomas using a crypt isolation technique
Authors: Sugai Tamotsu , Habano Wataru , Nakamura Shin‐ichi , Jiao Yu‐Fei , Higuchi Taro , Inomata Masaaki , Chiba Toshimi
Published: September 2002

Background and Aim: Current evidence suggests a possible relationship between DNA ploidy status and Ki‐ras gene mutations in human cancers. However, the conventional method does not enable accurate determination of DNA ploidy status of a tumor cell. The present study attempts to clarify whether Ki‐ras gene mutations are associated with DNA ploidy status in sporadic colorectal carcinomas using a crypt isolation technique coupled with DNA cytometric sorting. Methods: Polymerase chain reaction and single‐strand conformation polymorphism and direct sequencing were used to analyze Ki‐ras gene mutations in 82 sporadic colorectal carcinomas: 21 diploid, 12 aneuploid, and 49 multiploid. In addition, microsatellite instability (MSI) was assessed using seven microsatellite markers to study the relationship to Ki‐ras mutations. Results: Ki‐ras mutations were found in 12 of 21 diploid carcinomas and in 8 of 12 aneuploid carcinomas. In contrast, Ki‐ras gene mutations were detected infrequently in the 34 multiploid carcinomas examined, 8 of which were seen in diploid populations and 10 in aneuploid populations. On the other hand, Ki‐ras gene mutations were inversely correlated with MSI, which was found in diploid carcinomas only. Conclusions: The low frequency of Ki‐ras gene mutations that we observed in multiclonal colorectal carcinomas suggests that development of multiclonal colorectal carcinoma may involve a mechanism different from that involved in the development of diploid or aneuploid colorectal carcinomas. Cytometry (Comm. Clin. Cytometry) 46:345–350, 2001. © 2001 Wiley‐Liss, Inc.
ATP release from the electric organ of Torpedo and from Xenopus oocytes
Authors: Escalada Artur , Aleu Jordi , Bodas Elena , Martín‐Satué Mireia , Felipe Antonio , Marsal Jordi , Gómez de Aranda Inmaculada , Pujol Gemma , Solsona Carles
Published: September 2002

A field‐stimulated electric organ generated an electric field and release of a large quantity of ATP. Oocytes injected with mRNA from a Torpedo electric organ released ATP when stimulated with carbamylcholine. We set up a configuration recording that let us simultaneously monitor the oocyte ionic currents and ATP release from a single oocyte. Hyperpolarization pulses applied to Xenopus oocytes induced an inward current and release of ATP independently of the expression of the ClC‐0 chloride channel. The current was insensitive to substitution of ions in the extracellular saline solution, either anions or cations. The reversal potential of the current was established between +40 and +100 mV, which is in the same range as the equilibrium potential of ATP–4. There was a correlation between the magnitude of the inward current and the amount of ATP released. The inward current closed slowly. During this closing period there was still release of ATP, which is sensitive to the holding potential. Positive potentials cut the amount of ATP released. The evoked current and ATP release were both sensitive to inhibitors of E‐NTPDase activity, such as suramin, 4‐acetamido‐4′isothiocyanatostilbene‐2,2′‐disulfonic acid (SITS), 4,4′diisothiocyanatostilbene‐2′‐disulfonic acid (DIDS), and a high concentration of calcium and gadolinium ions. The expression of CD39 increased the size of the hyperpolarizing induced current. By reverse transcription polymerase chain reaction, we found a protein homologous to CD39. The relationship between the results obtained in the electric organ and oocytes is that, in both cases, stimulation or hyperpolarization causes a change in the intracellular ion concentration, producing an osmotic stress, which, in turn, triggers ATP release. Stimulation or hyperpolarization may alter the intercellular ion concentration, leading to osmotic stress and the release of ATP in both electric organ and oocytes. Drug Dev. Res. 52:34–43, 2001. © 2001 Wiley‐Liss, Inc.
TGF‐β1 perturbs vascular development and inhibits epithelial differentiation in fetal lung in vivo
Authors: Zeng Xin , Gray Mary , Stahlman Mildred T. , Whitsett Jeffrey A.
Published: September 2002

Members of the transforming growth factor β (TGF‐β) family of polypeptides have been implicated in morphogenesis and differentiation in numerous tissues, including the lung. In order to further define effects of TGF‐β signaling in lung morphogenesis, a constitutively active form of TGF‐β1 was expressed in respiratory epithelial cells of the fetal mouse lung in vivo. Expression of TGF‐β1 arrested lung morphogenesis in the pseudoglandular stage of development, inhibiting synthesis of differentiation‐dependent proteins, SP‐B, SP‐C, and CCSP, and maintaining embryonic patterns of staining for thyroid transcription factor‐1 (TTF‐1) and hepatocyte nuclear factor‐3β (HNF‐3β). The pulmonary mesenchyme was thickened and vascular density was increased by TGF‐β1. TGF‐β1 decreased expression of vascular endothelial growth factor‐A (VEGF‐A) mRNA and protein, and the abundance of Flk‐1 mRNA in the lung mesenchyme. Distribution of platelet‐endothelial cell adhesion molecule (PECAM)‐1, a marker of pulmonary blood vessels, was altered, and ultrastructural studies demonstrated that TGF‐β1 inhibited vascular development in the fetal lung. TGF‐β1 perturbed both epithelial cell differentiation and formation of the pulmonary vasculature, supporting the concept that precise control of signaling via the TGF‐β receptor pathway is critical for normal lung morphogenesis. © 2001 Wiley‐Liss, Inc.