bluuebunny/crossref_metadata_2025 huggingface dataset:
Role of strong intramolecular N—H...N hydrogen bonds in determining the conformation of adenosine-receptor antagonists
Authors: Ferretti Valeria , Pretto Loretta , Tabrizi Mojgan Aghazadeh , Gilli Paola
Published: July 2006

Over the last few years many efforts have been devoted to the discovery of new adenosine antagonists which can selectively bind to one of the four adenosine receptors, called A1, A2A, A2B and A3, in order to develop new drugs with few side effects. The present paper reports the crystal structures of four newly synthesized antagonists belonging to the chemical class of pyrazolo-triazolo-pyrimidine derivatives, which display good affinity and selectivity properties towards the A2A or A3 receptor subtypes. These molecules assume an overall planar conformation due to the formation of strong intramolecular N—H...N hydrogen bonds. A systematic investigation on molecules containing the ureidic —NH—C(=O,S)—NH—C=N— fragment has shown that the formation of such interactions is a common feature for this class of compounds. The associated energy, evaluated through DFT calculations, is some 50.24 kJ mol−1, leading to the conclusion that the hydrogen bond, and consequently the planar conformation, is retained not only in the solid state but also in solution during the interaction of the molecule with its receptor.
Isomers and polymorphs of (E,E)-1,4-bis(nitrophenyl)-2,3-diaza-1,3-butadienes
Authors: Glidewell Christopher , Low John N. , Skakle Janet M. S. , Wardell James L.
Published: July 2006

The structures of five of the possible six isomers of (E,E)-1,4-bis(nitrophenyl)-2,3-diaza-1,3-butadiene are reported, including two polymorphs of one of the isomers. (E,E)-1,4-Bis(2-nitrophenyl)-2,3-diaza-1,3-butadiene, C14H10N4O4 (I), crystallizes in two polymorphic forms (Ia) and (Ib) in which the molecules lie across centres of inversion in space groups P21/n and P21/c, respectively: the molecules in (Ia) and (Ib) are linked into chains by aromatic π...π stacking interactions and C—H...π(arene) hydrogen bonds, respectively. Molecules of (E,E)-1-(2-nitrophenyl)-4-(3-nitrophenyl)-2,3-diaza-1,3-butadiene (II) are linked into sheets by two independent C—H...O hydrogen bonds. The molecules of (E,E)-1,4-bis(3-nitrophenyl)-2,3-diaza-1,3-butadiene (III) lie across inversion centres in the space group P21/n, and a combination of a C—H...O hydrogen bond and a π...π stacking interaction links the molecules into sheets. A total of four independent C—H...O hydrogen bonds link the molecules of (E,E)-1-(3-nitrophenyl)-4-(4-nitrophenyl)-2,3-diaza-1,3-butadiene (IV) into sheets. In (E,E)-1,4-bis(4-nitrophenyl)-2,3-diaza-1,3-butadiene (V) the molecules, which lie across centres of inversion in the space group P21/n, are linked by just two independent C—H...O hydrogen bonds into a three-dimensional framework.
The low-temperature phase III structure and phase transition behaviour of cyclohexanone
Authors: Ibberson Richard M.
Published: July 2006

The crystal structure of phase III of perdeuterocyclohexanone, C6D10O, has been determined at 5 K using high-resolution neutron powder diffraction. Below its melting point of 245 K cyclohexanone forms a plastic crystal in the space group Fm\bar 3m. On cooling below 225 K the crystal transforms to the monoclinic phase III structure in the space group P21/n. The orthorhombic phase II structure exists under high pressure, but the triple point for all three phases is close to atmospheric pressure. Details of the phase II structure are also reported at 4.8 kbar (273 K) and ambient pressure. The phase behaviour of the compound and isotope effects are discussed.
Neutron and electron diffraction studies of La(Zn1/2Ti1/2)O3 perovskite
Authors: Ubic Rick , Hu Yi , Abrahams Isaac
Published: July 2006

The crystallography and microwave dielectric properties of La(Zn1/2Ti1/2)O3 (LZT) ceramics prepared via the mixed-oxide route were investigated in this study. While samples were largely single phase, small amounts of ZnO impurity were detected in sintered pellets. Observed reflections in electron and neutron diffraction patterns indicate that the symmetry of LZT is P21/n. The B site is ordered on {110} or pseudocubic {111}, but the presence of the pseudocubic 1\over2(111) reflection is in itself insufficient to indicate the existence of such order. Rietveld refinements of the neutron diffraction data yield an excellent fit for such a model. The structure is highly twinned, with variants related through common {211} composition planes and 90° rotations about 〈011〉. The microwave dielectric properties measured were ∊
r
= 34, Qf = 36 090 and τ
f
= −70 MK−1.
Intra- and intermolecular interactions in small bioactive molecules: cooperative features from experimental and theoretical charge-density analysis
Authors: Munshi Parthapratim , Guru Row Tayur N.
Published: July 2006

The topological features of the charge densities, ρ(r), of three bioactive molecules, 2-thiouracil [2,3-dihydro-2-thioxopyrimidin-4(1H)-one], cytosine [4-aminopyrimidin-2(1H)-one] monohydrate and salicylic acid (2-hydroxybenzoic acid), have been determined from high-resolution X-ray diffraction data at 90 K. The corresponding results are compared with the periodic theoretical calculations, based on theoretical structure factors, performed using DFT (density-functional theory) at the B3LYP/6-31G** level. The molecules pack in the crystal lattices via weak intermolecular interactions as well as strong hydrogen bonds. All the chemical bonds, including the intra- and intermolecular interactions in all three compounds, have been quantitatively described by topological analysis based on Bader's quantum theory of `Atoms In Molecules'. The roles of interactions such as C—H...O, C—H...S, C—H...π and π...π have been investigated quantitatively in the presence of strong hydrogen bonds such as O—H...O, N—H...O and N—H...S, based on the criteria proposed by Koch and Popelier to characterize hydrogen bonds and van der Waals interactions. The features of weak intermolecular interactions, such as S...S in 2-thiouracil, the hydrogen bonds generated from the water molecule in cytosine monohydrate and the formation of the dimer via strong hydrogen bonds in salicylic acid, are highlighted on a quantum basis. Three-dimensional electrostatic potentials over the molecular surfaces emphasize the preferable binding sites in the structure and the interaction features of the atoms in the molecules, which are crucial for drug–receptor recognition.
Structures and phase transitions in the ordered double perovskites Ba2BiIIIBiVO6 and Ba2BiIIISbVO6
Authors: Kennedy Brendan J. , Howard Christopher J. , Knight Kevin S. , Zhang Zhaoming , Zhou Qingdi
Published: July 2006

High-resolution neutron powder diffraction has been used to investigate the structures and phase transitions in the double perovskites Ba2Bi3+Bi5+O6 (dibarium dibismuth hexaoxide) and Ba2BiSbO6 (dibarium bismuth antimony hexaoxide) in the temperature ranges 4.2–973 and 4.2–625 K, respectively. The charge-ordered bismuthate adopts four structures in the temperature range – monoclinic in P21/n, monoclinic in I2/m, rhombohedral in R\bar 3, and finally cubic in Fm\bar 3 m. The low-temperature monoclinic structure has been determined for the first time. The transitions from P21/n to I2/m, at 132 K, and R\bar 3 to Fm\bar 3m, at 820 K, are tricritical in nature; the transition from I2/m to R\bar 3 at ca 430 K is discontinuous. The behaviour of Ba2BiSbO6 is very similar, except that the transition temperatures are lower – 250 K for I2/m to R\bar 3 and 515 K for R\bar 3 to Fm\bar 3m – and the low-temperature structure is not formed at all. The R\bar 3 to Fm\bar 3 m transition in this compound is closer to second order in nature, although there is evidence for some contribution from higher-order terms.
Searching the Cambridge Structural Database for the `best' representative of each unique polymorph
Authors: van de Streek Jacco
Published: July 2006

A computer program has been written that removes suspicious crystal structures from the Cambridge Structural Database and clusters the remaining crystal structures as polymorphs or redeterminations. For every set of redeterminations, one crystal structure is selected to be the best representative of that polymorph. The results, 243 355 well determined crystal structures grouped by unique polymorph, are presented and analysed.
Antitumor activity of chimeric immunoreceptor gene‐modified Tc1 and Th1 cells against autologous carcinoembryonic antigen‐expressing colon cancer cells
Authors: Sasaki Takeshi , Ikeda Hiroaki , Sato Masayoshi , Ohkuri Takayuki , Abe Hiroyuki , Kuroki Masahide , Onodera Masafumi , Miyamoto Masaki , Kondo Satoshi , Nishimura Takashi
Published: July 2006

To generate tumor‐specific and interferon (IFN)‐γ‐producing Tc1 and Th1 cells applicable for many cancer patients, we previously developed a protocol for generating carcinoembryonic antigen (CEA)‐specific Tc1 and Th1 cells from healthy human T cells by transduction with a lentivirus containing a chimeric immunoglobulin T‐cell receptor (cIgTCR) gene composed of single‐chain variable fragments from an anti‐CEA‐specific monoclonal antibody fused to an intracellular signaling domain of CD28 and CD3ζ. These cells, designated Tc1‐T and Th1‐T bodies, respectively, showed strong antitumor activity against CEA‐expressing tumor cells in RAG2–/– mice when both of them were transferred. However, it remains unclear whether it is possible to generate Tc1‐T and Th1‐T bodies from cancer patients with defective T‐cell function because of significant immunosuppression. Here, we prepared Tc1‐T and Th1‐T bodies from T cells of a colon cancer patient, and asked whether these T bodies can exert effective T‐cell function against autologous tumor cells. These T bodies showed high cytotoxicity and produced IFN‐γ in response to CEA‐expressing autologous tumor cells, even in the presence of soluble CEA. It was also demonstrated that Th1‐T bodies supported the survival of Tc1‐T bodies through cell‐to‐cell interactions. Furthermore, our protocol utilized retrovirus for cIgTCR transduction to achieve better induction efficiency compared to lentivirus‐mediated transduction. Taken together, our findings here indicate that retrovirally transduced Tc1‐T and Th1‐T bodies will become a promising strategy for adoptive immunotherapy of human cancer. (Cancer Sci 2006; 97: 920–927)
Immunopathogenesis of psoriasis
Authors: Lee Michael R , Cooper Alan J
Published: July 2006

This paper reviews the pathogenesis of psoriasis, in particular, the immunological cascade in psoriasis. Psoriasis is an immune‐mediated skin disease where the T cell plays a pivotal role in the pathogenesis of the disease. The critical steps involved in the pathogenesis include Langerhans cell activation and maturation by antigens in the skin, activation of the T cell by mature Langerhans cells, differentiation and expansion of T cells within the lymph nodes, trafficking of activated T cells from the lymph node to the skin and the subsequent release of cytokines. These cytokines are responsible for epidermal and vascular hyperproliferation and pro‐inflammatory effects. Each of these steps provides an opportunity for biological agents designed to block the psoriatic immunological cascade. This paper reviews the immunopathogenesis of psoriasis. Biologic agents in psoriasis, to be published separately, reviews the new biologic therapies that aim to selectively block the immunological steps implicated in the pathogenesis of psoriasis outlined in this paper.
Merkel cell carcinoma (primary cutaneous neuroendocrine carcinoma): An overview on management
Authors: Veness Michael J
Published: July 2006

Merkel cell carcinoma is an uncommon but aggressive primary cutaneous neuroendocrine (small cell) carcinoma. There is ongoing debate regarding the optimal treatment of this disease. The early literature comprised small institutional studies with inherent weaknesses. Recent data have emerged from larger studies, including those from Australian institutions, that adds support to a multimodality approach as best practice. Despite this, the outcome for patients with unfavourable disease remains poor and in most series 25–30% of patients die as a direct result of Merkel cell carcinoma. The head and neck is the commonest site for presentation (50–60%) and wide excision (2–3 cm) of the primary lesion is usually recommended, although achieving this is often difficult within functional and cosmetic constraints. All clinically node‐negative patients should be considered candidates for elective nodal treatment and those with clinical nodal disease should undergo nodal dissection and adjuvant radiotherapy. Recent evidence suggests that patients treated with surgery and adjuvant locoregional radiotherapy experience a better disease‐free survival compared with those undergoing surgery alone. The role of platinum‐based chemotherapy is evolving. The aim of this article is to discuss relevant issues in the management of a patient with Merkel cell carcinoma.
Use of 5% imiquimod cream in the treatment of facial basal cell carcinoma: A 3‐year retrospective follow‐up study
Authors: Vun Yin , Siller Greg
Published: July 2006

There has been considerable research into the safety and efficacy of topical 5% imiquimod cream for the treatment of skin cancers in recent years, in particular superficial and nodular basal cell carcinomas. However, there are limited long‐term follow‐up studies. This retrospective study aims to determine the efficacy of 5% imiquimod cream in the treatment of facial basal cell carcinomas over 3 years. Medical records of 12 patients treated with 5% imiquimod cream at a private dermatology practice during 2001 and 2002 were retrospectively reviewed. Target tumours included superficial and nodular basal cell carcinomas, giving a total lesion number of 19. Patients were commenced on a once daily treatment regimen for up to 9 weeks, and given rest periods as required according to the severity of application site reactions. We found that 5% imiquimod cream is an effective treatment option for superficial and nodular basal cell carcinomas, giving a clearance rate of 89.5% at an average of 39 months of follow up.
Prevalence of atopy in a population of hairdressing students and practising hairdressers in Melbourne, Australia
Authors: Roberts Hugh , Frowen Kathryn , Sim Malcolm , Nixon Rosemary
Published: July 2006

Hairdressers are one of the largest groups affected by occupational contact dermatitis. In this population‐based study, 193 trainee hairdressers and 184 practising hairdressers each completed a questionnaire and had their hands examined. Participants were asked about past or present atopy including eczema, asthma or hayfever, which occurred in 59.2%, and were individually correlated with a history of occupational skin problems. Almost 60% of hairdressers and trainees had experienced changes on their hands since commencing hairdressing, while 29% had evidence of abnormal skin on examination on the day of participation. Atopic individuals, who plan to work in a career such as hairdressing with known high rates of occupational contact dermatitis, should be advised to care for and protect their skin from the outset to prevent the development of this condition. There has been little awareness of this issue in Australia, despite longstanding knowledge of the association of hairdressing and contact dermatitis.
Invasive squamous cell carcinoma after treatment of carcinoma in situ with 5% imiquimod cream
Authors: Goh Michelle SY
Published: July 2006

Squamous cell carcinoma in situ has the potential to progress to invasive squamous cell carcinoma. This report presents two cases of punch biopsy‐proven squamous cell carcinoma in situ, treated with once‐daily application of 5% imiquimod cream for 6 weeks. Both patients developed moderate local inflammatory reactions during treatment. The first patient demonstrated clinical clearance of the scalp lesion after treatment. Two months later, he re‐presented with a subcutaneous nodule at the same site. Histology was consistent with recurrent squamous cell carcinoma. Five months following excision of the recurrent tumour, he presented with metastatic squamous cell carcinoma to a cervical lymph node. The second patient had low‐grade chronic lymphocytic leukaemia and presented with squamous cell carcinoma in situ of the leg that failed to clear clinically after treatment with imiquimod. He presented 4 months later with a focus of invasive squamous cell carcinoma within the lesion.
Wolf’s isotopic response: Rosacea appearing at the site of healed herpes zoster
Authors: Sezer Engin , Koseoglu Resit D , Filiz Nurper
Published: July 2006

A 40‐year‐old man developed an erythematous rash on the right side of his face 3 weeks after a herpes zoster infection at the same location. Examination revealed an erythematous papular eruption and telangiectasias along the ophthalmic and maxillary divisions of the right trigeminal nerve, exactly at the site of the consistent with previous herpes zoster infection, Wolf’s isotopic response. Histological examination showed vascular ectatic dilatation and perivascular and perifollicular infiltration of lymphocytes and histiocytes consistent with rosacea. The rash was resistant to oral doxycycline and topical metronidazole 1% cream and resolved with oral isotretinoin therapy.
Juxta‐clavicular beaded lines
Authors: Franco Gennaro , Donati Pietro , Muscardin Luca , Maini Antonio , Morrone Aldo
Published: July 2006

We present a case series of 63 patients diagnosed with juxta‐clavicular beaded lines. This condition is more frequent in dark‐skinned people and corresponds to an anatomical variant of simple sebaceous hyperplasia. In view of the strong reactivity of the melanocytes in dark‐skinned people, and of the possible hypochromic results, no treatment is advised.
Satisfaction with Daily Occupations: Construct validity and test–retest reliability of a screening tool for people with mental health disorders
Authors: Eklund Mona , Gunnarsson A. Birgitta
Published: July 2006

Background/Aim:  In occupational therapy research and in clinical practice there is a need for valid, reliable and easily administered measures. For research and screening purposes, the Satisfaction with Daily Occupations (SDO) instrument was developed. It addresses work, leisure, domestic tasks and self‐care and generates a satisfaction and an activity level score. This study investigated its construct validity, internal consistency and test–retest reliability in 55 clients visiting occupational therapists in outpatient mental health care.

Methods:  The SDO was administered on two occasions with a 1‐week interval, and data on the Canadian Occupational Performance Measure (COPM), psychosocial functioning and self‐rated health were collected on the first of these occasions.

Results:  In contrast to what was expected, the relationships between the SDO scores and the COPM scores were low. The strongest relationship between the SDO satisfaction score and any other variable was to psychosocial functioning. These variables shared 23% of the variance. Internal consistency for the satisfaction score was acceptable, alpha = 0.75 on the second occasion, and the test–retest reliability was good; rs = 0.84 for the satisfaction score and rs = 0.92 for the activity level.

Conclusions:  The results indicated that the SDO has satisfactory reliability. The instrument targets a specific construct, as compared to the COPM and the measurements of self‐rated health and psychosocial functioning. Thus, the SDO and the COPM satisfaction scale seem to assess different phenomena, probably because the SDO has predefined items, not specifically targeting a certain client's problematic occupations, whereas the COPM is based on self‐defined problems. The instruments may therefore supplement each other.
Quality and quantity of paediatric research: An analysis of the OTseeker database
Authors: Hoffmann Tammy , McKenna Kryss , Hadi Tahnya , Bennett Sally , McCluskey Annie , Tooth Leigh
Published: July 2006

Aim:  This study aimed to analyse the quantity and quality of paediatric research evidence contained in the OTseeker database and to compare the findings with surveys of paediatric occupational therapy practice.

Methods:  In June 2005, systematic reviews and randomised controlled trials contained in OTseeker were analysed according to year of publication and the client diagnostic groups and interventions addressed. The internal validity scores of the trials were determined (according to the PEDro scale (partitioned)) and the outcome measures used extracted.

Results:  Of 3294 papers contained in OTseeker, 372 (11.3%) were related to paediatrics. The mean internal validity score of the trials was 2.5/8. The five most frequently studied diagnostic groups were mental health/psychosocial issues, neurology, learning disabilities, developmental delay and ‘other’. There was much variation in the outcome measures used, with a large number of outcome measures used in only one or a few studies. The five most frequently studied interventions were behavioural interventions, consumer education, psychosocial techniques, interventions for carers/parents and developmental therapy.

Conclusion:  OTseeker contains a considerable amount of research relevant to paediatric occupational therapy practice. There was some congruence between the papers and practice surveys regarding client diagnostic groups and interventions, but little between the outcome measures used in research and those used in clinical practice.
Attitudes of entry level occupational therapy doctoral students towards inclusion for students with disabilities
Authors: Mu Keli , Gabriel Franck Linda , Konz Christina
Published: July 2006

Background/Aims:  The increasing popularity of inclusive education for students with disabilities and the attitudes towards it inevitably affect school‐based occupational therapy practice. This survey study investigated the attitudes of entry‐level occupational therapy doctoral (EOTD) students towards inclusive education and the effect of professional education on their perception.

Methods:  A total of 62 EOTD students responded to a self‐developed questionnaire, Attitudes and Inclusive Education Survey, yielding a response rate of 91.2%.

Results:  Results of the study revealed that entry level occupational therapy doctoral students have positive attitudes towards inclusive education and believe that the inclusion movement has an inevitable impact on school‐based occupational therapy practice. Professional education in occupational therapy might positively affect students’ attitudes.

Conclusion:  Given the close association between one's attitude and behaviour, the findings of the study are particularly encouraging. Future research needs to further examine school‐based occupational therapy practice in inclusive environments.
Epigenetic regulation of the imprinted U2af1‐rs1 gene during retinoic acid‐induced differentiation of embryonic stem cells
Authors: Andollo Noelia , Boyano María D. , Andrade Ricardo , Aréchaga Juan M.
Published: July 2006

Epigenetic modifications such as DNA methylation and changes in chromatin structure are changes in the chemical composition or structure of DNA that work by regulating gene expression. Their mechanisms of action have been generally studied in imprinted genes. The present work analyzes the involvement of these mechanisms in the expression of the U2af1‐rs1 imprinted gene during the differentiation process of embryonic stem (ES) cells induced by retinoic acid. By DNA digestion with methylation‐dependent or independent restriction enzymes and consecutive Southern blot, we have found that methylation of the U2af1‐rs1 gene increases in differentiated ES cells and in embryoid bodies. However, northern blot and real‐time reverse transcription–polymerase chain reaction analysis showed a higher expression of the U2af1‐rs1 gene in differentiated ES cells and in embryoid bodies than in undifferentiated ones. On the other hand, the sensitivity to DNase‐I assay demonstrated an open chromatin conformation for differentiated cells with regard to undifferentiated ES cells. Our results suggest that the expression of the U2af1‐rs1 gene would be regulated by changes in chromatin structure rather than by DNA methylation during the RA‐induced process of differentiation of ES cells.
Murine mesenchymal stem cells isolated by low density primary culture system
Authors: Eslaminejad Mohamadreza Baghaban , Nikmahzar Aghbibi , Taghiyar Leila , Nadri Samad , Massumi Mohamad
Published: July 2006

Murine mesenchymal stem cells (mMSC) and the difficult task of isolation and purification of them have been the subject of rather extensive investigation. The present study sought to isolate these cells from two different mouse strains, one outbred and the other inbred, primarily through a relatively simple but novel approach, the most important feature of which was the low density primary culture of bone marrow cells. For this purpose, mononuclear cells from either NMRI or BALB/c bone marrow were plated at about 500 cells per well of 24‐well plates and incubated for 7 days. At this point, the fibroblastic clones that had emerged were pooled together and expanded through several subcultures. To investigate the mesenchymal nature, we differentiated the cells into the osteoblastic, chondrocytic and adipocytic lineages in different subcultures up to passage 10. According to the results, 1 week after culture initiation, several clones each comprising several fibroblastic cells appeared in each plate. The cells from different passages were capable of differentiating into corresponding skeletal tissues. In the present investigation, the best culture condition for maximum proliferation and also the expression of certain surface marker on isolated cells were examined. In this term the two murine strains showed some differences.
Esg1, expressed exclusively in preimplantation embryos, germline, and embryonic stem cells, is a putative RNA‐binding protein with broad RNA targets
Authors: Tanaka Tetsuya S. , Lopez de Silanes Isabel , Sharova Lioudmila V. , Akutsu Hidenori , Yoshikawa Toshiyuki , Amano Hisayuki , Yamanaka Shinya , Gorospe Myriam , Ko Minoru S. H.
Published: July 2006

In our earlier attempt to identify genes involved in the maintenance of cellular pluripotency, we found that KH‐domain protein Embryonal stem cell‐specific gene 1 (Esg1) showed similar expression patterns to those of Oct3/4 (Pou5f1), whereas the forced repression of Oct3/4 in mouse embryonic stem cells immediately downregulated the expression of Esg1. Here we further confirm this overlap by in situ hybridization and immunohistochemical analyses. Both Esg1 transcript and protein exist in the egg and preimplantation embryos. At embryonic day 3.5, blastocyst stage, however, ESG1 protein was more abundant in the inner cell mass (ICM) than in trophectoderm (TE), whereas Esg1 transcript was detected in both the ICM and the TE, particularly in the polar trophectoderm. The presence of an RNA‐binding KH‐domain in ESG1 led us to search for and identify 902 target transcripts by microarray analysis of immunoprecipitated ESG1 complex. Interaction of 20 target mRNA with ESG1, including Cdc25a, Cdc42, Ezh2, Nfyc and Nr5a2, was further validated by reverse transcriptase–polymerase chain reaction of the immunoprecipitation material, supporting the notion that ESG1 is an RNA‐binding protein which associates with specific target transcripts.
Study on ASTM E399 and ASTM E1921 standards
Authors: SAID G.
Published: July 2006

Costs of ASTM E399 and ASTM E1921 tests, which were developed to determine the fracture toughness (KIc) and the ductile–brittle transition temperature of ferritic steels, respectively, are considered high and the procedures are also very complicated. In this study, a method, which is more cost‐effective and easier to carry out, is proposed.
Demonstration and Characterization of Mutations Induced by Helicobacter pylori Organisms in Gastric Epithelial Cells
Authors: Yao Yuan , Tao Hong , Park Dong Il , Sepulveda Jorge L. , Sepulveda Antonia R.
Published: July 2006

Background:  Helicobacter pylori gastritis increases gastric cancer risk. Microsatellite instability‐type mutations are secondary to deficient DNA mismatch repair. H. pylori gastritis is more frequent in patients with microsatellite instability‐positive gastric cancers, and H. pylori organisms independently of inflammation can reduce DNA mismatch repair protein levels, raising the hypothesis that H. pylori organisms might lead to mutagenesis during infection.

Materials and Methods:  Mutations were detected using a green fluorescent protein reporter vector (pEGFP‐CA13). Gastric cancer AGS cells transfected with pEGFP‐CA13 were cocultured with H. pylori or Escherichia coli. The numbers of green fluorescent protein (GFP)‐positive cells were determined, and GFP, hMSH2, and hMLH1 protein levels were measured by Western blot. The effect of H. pylori on CpG methylation status of hMLH1 was determined by methylation‐specific polymerase chain reaction.

Results:  GFP levels and GFP‐positive cell numbers in AGS cells cocultured with H. pylori significantly increased, as the levels of hMLH1 and hMSH2 dropped. H. pylori cocultures induced low‐level CpG methylation of the hMLH1 promoter. Sequence analysis of cells cocultured with H. pylori showed an increased number of frameshift mutations and point mutations as compared to cells not cocultured with H. pylori (p = .03 and p = .001, respectively).

Conclusions:  This is the first report showing that H. pylori bacteria may lead to accumulation of genomic mutations, independently of underlying inflammation. This is associated with reduced DNA mismatch repair, and is at least in part associated with CpG methylation of the hMLH1 promoter. These data support the notion that H. pylori‐induced mutations and epigenetic alterations in gastric epithelial cells during chronic gastritis may contribute to an increased risk of gastric cancer associated with H. pylori infection.
Production of Reactive Oxygen Species in Peripheral Blood is Increased in Individuals with Helicobacter pylori Infection and Decreased after its Eradication
Authors: Mashimo Masayuki , Nishikawa Manabu , Higuchi Kazuhide , Hirose Masaki , Wei Qian , Haque Anwarul , Sasaki Eiji , Shiba Masatsugu , Tominaga Kazunari , Watanabe Toshio , Fujiwara Yasuhiro , Arakawa Tetsuo , Inoue Masayasu
Published: July 2006

Background:  Helicobacter pylori infection has been reported to cause gastroduodenal ulcer, mucosa‐associated lymphoid tissue lymphoma, and gastric cancer. Recent studies have suggested that H. pylori infection may also associate with other diseases, including hematologic and dermatologic disorders, and cardiovascular injury, by unknown mechanisms.

Methods:  Production of reactive oxygen species (ROS) was determined in peripheral blood samples from 86 patients (34 H. pylori‐negative and 52 H. pylori‐positive subjects) using a highly sensitive chemiluminescence probe, L‐012 (8‐amino‐5‐chloro‐7‐phenylpyrido(3,4‐d) pyridazine‐1 and 4 (2H, 3H) dione). Eleven H. pylori‐positive individuals were also analyzed their ROS production in peripheral blood after H. pylori eradication.

Results:  ROS production was significantly higher in individuals with H. pylori infection than in those without infection. Enhanced production of ROS was decreased significantly after eradication of H. pylori. No correlation was found between the extent of ROS production and sex, age, smoking status, alcohol ingestion, use of medications, or serum level of C‐reactive protein.

Conclusion:  These findings suggest that ROS production was enhanced in peripheral blood by H. pylori infection. Chemiluminescence analysis of blood samples using L‐012 permits evaluation of systemic oxidative stress in patients with H. pylori infection.
Gastric Epithelial Expression of Macrophage Migration Inhibitory Factor is not Altered by Helicobacter pylori Infection in Humans
Authors: Lebiedz Pia , Heidemann Jan , Lugering Andreas , Riedel Susanne , Herbst Hermann , Domschke Wolfram , Kucharzik Torsten , Maaser Christian
Published: July 2006

Background:  Recent reports have shown an upregulation of macrophage migration inhibitory factor (MIF) during gastric ulcer development in a rat model and elevated counts of MIF‐positive cells in biopsies from Helicobacter pylori‐infected patients. H. pylori infection is a proven cofactor in humans causing gastritis and gastric ulcers. The aim of this study was to characterize MIF expression in human gastric epithelial cells in response to H. pylori.

Methods:  MIF mRNA and MIF protein expression was detected in human gastric epithelial cell lines after stimulation with proinflammatory cytokines or infection with H. pylori (cagA+/vacA+) using real‐time reverse transcriptase–polymerase and enzyme‐linked immunosorbent assay. Interleukin‐8 secretion was measured as positive control. MIF mRNA and MIF protein expression was assessed in H. pylori‐positive and ‐negative human gastric biopsy samples.

Results:  While interleukin‐8 mRNA expression and interleukin‐8 secretion were upregulated in gastric epithelial cells in vitro after H. pylori infection, no changes in MIF mRNA expression and MIF secretion could be detected. We found no significant differences in MIF expression in total RNA extracted from gastric biopsy tissue when comparing H. pylori‐positive to control patients. Likewise, MIF protein expression in gastric epithelium was unaffected by H. pylori infection as compared to uninfected tissue.

Conclusions:  While an increased MIF expression and positive effects of MIF blockade in ulcer healing have been shown in a rodent model and elevated numbers of MIF‐positive cells have been found in H. pylori‐infected human tissue, we herein could not confirm any differences in human gastric epithelial MIF expression and secretion after H. pylori infection in vitro and in vivo.
A Prospective Study for the Association of Helicobacter pylori Infection to a Multidimensional Measure for Recurrent Abdominal Pain in Children
Authors: Malaty Hoda M. , Abudayyeh Suhaib , Graham David Y. , Gilger Mark A. , Rabeneck Linda , O'Malley Kimberly
Published: July 2006

Background:  There is a controversial association between Helicobacter pylori infection and recurrent abdominal pain (RAP) in childhood and inconsistent information on specific symptomatology of the infection.

Aims:  To examine the prevalence of H. pylori infection among children with RAP compared to asymptomatic children.

Methods:  Two prospective studies were conducted. The first study enrolled 223 children diagnosed with RAP from two pediatric gastroenterology clinics in Houston, Texas. Children were qualified if they were identified by their physician as having RAP. A new multidimensional measure for RAP (MM‐RAP) consisting of four scales (pain intensity scale, symptoms scale, disability scale, and satisfaction scale) was administered to each child/parent. The second study enrolled 330 asymptomatic children from the same community who did not have any upper gastrointestinal symptoms. Symptomatic and asymptomatic children underwent 13C‐urea breath testing.

Results:  In the first study, the prevalence of H. pylori in children with RAP was 11% and fell with age from 20% at age ≤ 5 years to 7% for children > 10 years (OR = 2.7, 95% CI = 0.7–11.2). There was no association between the mother's educational level and H. pylori prevalence; (12% among children whose mothers completed college versus 11% among those who had elementary school, p = .8). No relationship was found between H. pylori and mean scores of the RAP scales. In the second study, the prevalence of H. pylori in asymptomatic children was 17% and increased with age from 11% for children ≤ 5 years to 40% for children > 10 years (OR = 5.4, 95% CI = 2.0–13.8). The mother's educational level was inversely correlated with H. pylori (OR = 3.0, 95% CI = 2.2–6.1, p < .01).

Conclusions:  The epidemiologic patterns of H. pylori infection differed significantly between symptomatic and asymptomatic children. Younger children suffering from RAP are more likely to be infected with H. pylori than older children with the same complaint, suggesting that early acquisition may manifest in symptoms that lead to clinic visits.
Is Helicobacter pylori a True Microaerophile?
Authors: Bury‐Moné Stephanie , Kaakoush Nadeem O. , Asencio Corinne , Mégraud Francis , Thibonnier Marie , De Reuse Hilde , Mendz George L.
Published: July 2006

Background:  There is no general consensus about the specific oxygen and carbon dioxide requirements of the human pathogen Helicobacter pylori. This bacterium is considered a microaerophile and consequently, it is grown under atmospheres at oxygen tensions 5–19% and carbon dioxide tensions 5–10%, both for clinical and basic and applied research purposes. The current study compared the growth of H. pylori in vitro, under various gas atmospheres, and determined some specific changes in the physiology of bacteria grown under different oxygen partial pressures.

Methods:  Measurements of bacterial growth under various conditions were carried out employing classical solid and liquid culture techniques. Enzymatic activities were measured using spectrophotometric assays.

Results:  H. pylori and all the other Helicobacter spp. tested had an absolute requirement for elevated carbon dioxide concentrations in the growth atmosphere. In contrast with other Helicobacter spp., H. pylori can tolerate elevated oxygen tensions when grown at high bacterial concentrations. Under 5% CO2, the bacterium showed similar growth in liquid cultures under oxygen tensions from microaerobic (< 5%) to fully aerobic (21%) at cell densities higher than 5 × 105 cfu/ml for media supplemented with horse serum and 5 × 107 cfu/ml for media supplemented with β‐cyclodextrin. Evidence that changes occurred in the physiology of H. pylori was obtained by comparing the activities of ferredoxin:NADH (nicotinamide adenine dinucleotide) oxidoreductases of bacteria grown under microaerobic and aerobic atmospheres.

Conclusions:  H. pylori is a capnophile able to grow equally well in vitro under microaerobic or aerobic conditions at high bacterial concentrations, and behaved like oxygen‐sensitive microaerophiles at low cell densities. Some characteristics of H. pylori cells grown in vitro under microaerobic conditions appeared to mimic better the physiology of organisms grown in their natural niche in the human stomach.
Primary Levofloxacin Resistance and gyrA/B Mutations Among Helicobacter pylori in Japan
Authors: Miyachi Hideyuki , Miki Ikuya , Aoyama Nobuo , Shirasaka Daisuke , Matsumoto Yuko , Toyoda Masanori , Mitani Toshifumi , Morita Yoshinori , Tamura Takao , Kinoshita Shohiro , Okano Yoshie , Kumagai Shunichi , Kasuga Masato
Published: July 2006

Background:  Recent years have witnessed a decrease in the rate of Helicobacter pylori eradication due to antimicrobial resistance, clarithromycin or metronidazole resistance in particular. As one of the alternatives to the standard regimens, levofloxacin‐containing therapy has been considered a promising regimen. Nevertheless, there is a little information concerning the prevalence of levofloxacin resistance and this resistance mechanism.

Materials and Methods:  Levofloxacin susceptibility was examined using E‐test in 507 H. pylori strains clinically isolated in Japan from 2001 to 2004. Mutation patterns in the quinolone resistance‐determining regions of the gyrA and gyrB genes were evaluated, performing direct sequencing of 68 levofloxacin‐resistant and 50 susceptible strains.

Results:  Primary levofloxacin resistance was found in 76 (15.0%) strains. Fifty‐seven (83.8%) of 68 levofloxacin‐resistant strains analyzed had point mutations in gyrA at Asn‐87 or Asp‐91, while seven (14.0%) of 50 susceptible strains had gyrA mutations. There was a significant difference in the occurrence of gyrA mutations between levofloxacin‐resistant and ‐susceptible strains (p < .001). In levofloxacin‐resistant strains, the occurrence of gyrA mutations at Asn‐87 was most common regardless of minimal inhibitory concentration levels, and that of gyrA mutations at Asp‐91 tended to be associated with low‐level resistance. A double gyrA mutation at Asn‐87 and Asp‐91 might have an additional impact. As for gyrB, three (4.4%) of 68 levofloxacin‐resistant strains with no susceptible strains had mutations.

Conclusions:  Primary levofloxacin resistance was common in Japan and primarily related to gyrA mutations at Asn‐87 and Asp‐91.
Impact of Helicobacter pylori Eradication Therapy on Histologic Change in the Distal Esophagus
Authors: Toyoda Masanori , Shirasaka Daisuke , Aoyama Nobuo , Watanabe Yoshinori , Miki Ikuya , Morita Yoshinori , Matsumoto Yuko , Mitani Toshifumi , Miyachi Hideyuki , Tamura Takao , Kasuga Masato
Published: July 2006

Background:  Although cases of reflux esophagitis (RE) developing after treatment to eradicate Helicobacter pylori have been discussed in some detail, no reports are available concerning the histologic examination of RE both before and after eradication therapy.

Materials and methods:  Sixty‐one patients and 111 specimens were investigated using endoscopic and histologic techniques. The histologic findings including basal zone height, papillar height, Ki‐67 labeling index, and COX‐2 expression before and after treatment for H. pylori infection were compared with those in normal controls and patients with endoscopic RE.

Results:  Twelve months after eradication therapy, the incidence of newly developed endoscopic RE was 20% (5/25). Basal zone height and papillar height had increased at 1 month, but had returned to pretreatment levels after 12 months of eradication therapy. The Ki‐67 labeling index was significantly increased 1 and 12 months after eradication therapy compared to values before treatment. COX‐2 expression gradually increased after the treatment. The phenomena linked to esophagitis appeared after eradication therapy. However, the severity and extent of these signs were not so high after the treatment of H. pylori than those in patients with overt reflux esophagitis. Focusing on the patients with hiatal hernia, papillar height and Ki‐67 labeling index increased significantly after eradication therapy, values being almost the same as those in the patients with endoscopic RE.

Conclusions:  Hiatal hernia plays an important role in the possible occurrence of hidden RE after treatment for a H. pylori infection.
Comment on "Ongoing Adaptive Evolution of
ASPM
, a Brain Size Determinant in
Homo sapiens
" and "
Microcephalin
, a Gene Regulating Brain Size, Continues to Evolve Adaptively in Humans"
Authors: Currat Mathias , Excoffier Laurent , Maddison Wayne , Otto Sarah P. , Ray Nicolas , Whitlock Michael C. , Yeaman Sam
Published: July 2006

Mekel-Bobrov
et al
. and Evans
et al
. (Reports, 9 Sept. 2005, p. 1720 and p. 1717, respectively) examined sequence data from modern humans within two gene regions associated with brain development,
ASPM
and
microcephalin
, and concluded that selection of these genes must be ongoing. We show that models of human history that include both population growth and spatial structure can generate the observed patterns without selection.
Response to Comment on "Ongoing Adaptive Evolution of
ASPM
, a Brain Size Determinant in
Homo sapiens
" and "
Microcephalin
, a Gene Regulating Brain Size, Continues to Evolve Adaptively in Humans"
Authors: Mekel-Bobrov Nitzan , Evans Patrick D. , Gilbert Sandra L. , Vallender Eric J. , Hudson Richard R. , Lahn Bruce T.
Published: July 2006

Currat
et al
. present computer simulations to argue that the haplotype structure found at the
microcephalin
and
ASPM
genes can be better explained by demographic history rather than by selection. The demographic models they adopt, however, strongly contradict a decade of empirical research on human demographic history and do not account for the critical features of the data on which our argument for selection was based.
Tyrannosaur Life Tables: An Example of Nonavian Dinosaur Population Biology
Authors: Erickson Gregory M. , Currie Philip J. , Inouye Brian D. , Winn Alice A.
Published: July 2006

The size and age structures for four assemblages of North American tyrannosaurs—
Albertosaurus, Tyrannosaurus, Gorgosaurus
, and
Daspletosaurus
—reveal a pronounced, bootstrap-supported pattern of age-specific mortality characterized by relatively high juvenile survivorship and increased mortality at midlife and near the maximum life span. Such patterns are common today in wild populations of long-lived birds and mammals. Factors such as predation and entrance into the breeding population may have influenced tyrannosaur survivorship. This survivorship pattern can explain the rarity of juvenile specimens in museum collections.
Negative Coulomb Drag in a One-Dimensional Wire
Authors: Yamamoto M. , Stopa M. , Tokura Y. , Hirayama Y. , Tarucha S.
Published: July 2006

We observed negative Coulomb drag for parallel coupled quantum wires, in which electrons flow in the opposite directions between the wires. This only occurred under the conditions of strong correlation in the wires, that is, low density, high magnetic field, and low temperature, and cannot be addressed by a standard theory of momentum transfer. We propose a Coulomb drag model in which formation of a Wigner crystal state in the drag wire and a particle-like state in the drive wire is taken into account.
Electric Fields at the Active Site of an Enzyme: Direct Comparison of Experiment with Theory
Authors: Suydam Ian T. , Snow Christopher D. , Pande Vijay S. , Boxer Steven G.
Published: July 2006

The electric fields produced in folded proteins influence nearly every aspect of protein function. We present a vibrational spectroscopy technique that measures changes in electric field at a specific site of a protein as shifts in frequency (Stark shifts) of a calibrated nitrile vibration. A nitrile-containing inhibitor is used to deliver a unique probe vibration to the active site of human aldose reductase, and the response of the nitrile stretch frequency is measured for a series of mutations in the enzyme active site. These shifts yield quantitative information on electric fields that can be directly compared with electrostatics calculations. We show that extensive molecular dynamics simulations and ensemble averaging are required to reproduce the observed changes in field.
Crystal Structure of the Low-pH Form of the Vesicular Stomatitis Virus Glycoprotein G
Authors: Roche Stéphane , Bressanelli Stéphane , Rey Félix A. , Gaudin Yves
Published: July 2006

The vesicular stomatitis virus has an atypical membrane fusion glycoprotein (G) exhibiting a pH-dependent equilibrium between two forms at the virus surface. Membrane fusion is triggered during the transition from the high- to low-pH form. The structure of G in its low-pH form shows the classic hairpin conformation observed in all other fusion proteins in their postfusion conformation, in spite of a novel fold combining features of fusion proteins from classes I and II. The structure provides a framework for understanding the reversibility of the G conformational change. Unexpectedly, G is homologous to gB of herpesviruses, which raises important questions on viral evolution.
Teaching in Wild Meerkats
Authors: Thornton Alex , McAuliffe Katherine
Published: July 2006

Despite the obvious benefits of directed mechanisms that facilitate the efficient transfer of skills, there is little critical evidence for teaching in nonhuman animals. Using observational and experimental data, we show that wild meerkats (
Suricata suricatta
) teach pups prey-handling skills by providing them with opportunities to interact with live prey. In response to changing pup begging calls, helpers alter their prey-provisioning methods as pups grow older, thus accelerating learning without the use of complex cognition. The lack of evidence for teaching in species other than humans may reflect problems in producing unequivocal support for the occurrence of teaching, rather than the absence of teaching.