bluuebunny/crossref_metadata_2025 huggingface dataset:
THE THOMAS–FERMI–GOMBÁS ATOM MODELS IN WHICH THE ELECTRONS ARE GROUPED INTO n- AND nl-SHELLS AND A CALCULATION OF THE ATOMIC FORM FACTOR
Authors: TARASOV V. F.
Published: March 2004

This article, considers in detail P. Gombás's idea of grouping electrons into n- and nl-shells in the Thomas–Fermi theory of free atoms briefly, the TFG n- and TFG nl-models respectively). Using these models, exact analytical expressions for the total energy E and the atomic form factor F(κ) are obtained. All integrals of the TFG nl-model are computed by means of the hypergeometric functions 2F1(x), 3F2(x), F2(x,y) and FA(x1,…,x6) for the first time. In particular, Weizsäcker's gradient correction to the kinetic energy of the nl-th shell [Formula: see text] generates a new numerical triangle [Formula: see text] with coefficients bw=n+2l(n-l-1).
INFLUENCE OF CRYSTAL FIELD EXCITATIONS COUPLED TO LATTICE VIBRATIONS ON THERMODYNAMICAL PROPERTIES OF A TWO-LEVEL PARAMAGNET
Authors: ULNER J. , PEISERT J. , DURCZEWSKI K.
Published: March 2004

A two-level crystal field model in the presence of the phonon field is considered. Spins are arranged on a lattice and weakly coupled to the lattice oscillations of small amplitudes. The anticommutator Green function perturbative method up to the second order in the coupling constant is applied to find thermodynamical quantities. The magnetic spectral function, describing the crystal field excitations, influences these quantities. The effect is studied numerically and illustrated in figures. In particular, the influence of the coupling on the Schottky specific heat is shown.
ANALYSIS OF ALKALINE ATOMS IN ELLIPTIC STATES
Authors: HUANG YUNG-SHENG , CHANG FANG-LING , LIAW SY-SANG
Published: March 2004

This paper presents the coherent elliptic states (CES) of alkaline constructed from the spherical Rydberg wavefunctions generated by the B-spline method associated with Hartree–Fock approximation. To construct the elliptic orbit for alkaline is not straightforward. The core effect plays an important role for the formation of elliptic states especially in higher and lower eccentricity. When the eccentricity is not large (i.e. e=0.6), the physical quantities of CES of alkaline atoms can be theoretically calculated by the replacement with hydrogen atom.
CONSERVATIVE AND SHATTERING SOLUTIONS FOR SOME CLASSES OF FRAGMENTATION MODELS
Authors: BANASIAK JACEK
Published: March 2004

Equations describing processes of cluster fragmentation have received considerable attention in recent years due to their importance in modelling e.g. the polymer degradation, droplet break-up, or rock crushing. In this paper we shall consider two mathematically most interesting features of them. One of these is the so-called shattering fragmentation, that is, the decrease of the total mass of the system that is formally conservative. The other is the existence of multiple solutions which indicates that in some cases the equations do not give the full picture of the dynamics of the model. Shattering fragmentation, that is considered to be an analogous but opposite process to a better understood gelation in coagulation models, has been investigated in several papers whose interest was, however, restricted to coefficients of a particular form that allowed either explicit solutions or yielded to a probabilistic approach. There have been few attempts to provide a deeper analysis of the existence of multiple solutions; most authors confined themselves to noticing them. In the present paper we present a systematic approach to both problems using the semigroup theory, and link them to the characterization of the generator of the solution semigroup of the fragmentation equation. As a result we provide criteria for both existence and absence of shattering fragmentation as well as of multiple solutions for large classes of coefficients that include those considered in all earlier works.
A CLASS OF EVOLUTIONARY VARIATIONAL INEQUALITIES WITH VOLTERRA-TYPE TERM
Authors: RODRÍGUEZ-ARÓS A. , VIAÑO J. M. , SOFONEA M.
Published: March 2004

We consider a class of abstract evolutionary variational inequalities arising in the study of frictionless contact problems for linear viscoelastic materials with long-term memory. We prove an existence and uniqueness result, by using arguments of time-dependent elliptic variational inequalities and Banach's fixed point theorem. We then consider numerical approximation of the problem by introducing spatially semi-discrete, time semi-discrete and fully discrete schemes. For both schemes, we show the existence of a unique solution and derive error estimates. Finally, we apply the abstract results to the analysis and numerical approximation of the Signorini frictionless contact problem between two viscoelastic bodies with long-term memory.
SIMPLIFIED DYNAMICS AND OPTIMIZATION OF LARGE SCALE TRAFFIC NETWORKS
Authors: HERTY MICHAEL , KLAR AXEL
Published: March 2004

Simplified dynamic models for traffic flow on networks are derived from network models based on partial differential equations. We obtain simplified models of different complexity like models based on ordinary differential equations or algebraic models. Optimization problems for all models are investigated. Analytical and numerical properties are studied and comparisons are given for simple traffic situations. Finally, the simplified models are used to optimize large scale networks.
FINITE ELEMENT ERROR ANALYSIS OF SPACE AVERAGED FLOW FIELDS DEFINED BY A DIFFERENTIAL FILTER
Authors: DUNCA ADRIAN , JOHN VOLKER
Published: March 2004

This paper analyzes finite element approximations of space averaged flow fields which are given by filtering, i.e. averaging in space, the solution of the steady state Stokes and Navier–Stokes equations with a differential filter. It is shown that [Formula: see text], the error of the filtered velocity [Formula: see text] and the filtered finite element approximation of the velocity [Formula: see text], converges under certain conditions of higher order than [Formula: see text], the error of the velocity and its finite element approximation. It is also proved that this statement stays true if the L2-error of finite element approximations of [Formula: see text] and [Formula: see text] is considered. Numerical tests in two and three space dimensions support the analytical results.
A NUMERICAL METHOD FOR PROGRESSIVE LENS DESIGN
Authors: WANG JING , SANTOSA FADIL
Published: March 2004

The problem of progressive lens design can be posed as a variational problem. The necessary condition is a fourth-order nonlinear elliptic partial differential equation. The partial differential equation can be linearized using a perturbation approach. A numerical method using a special type of splines, chosen for their smoothness properties, is devised to solve the resulting PDE. The computational method is shown to be both convergent and efficient.
RESULTS ON THE CLASSIFICATION OF RATIONAL 3-TANGLES
Authors: CABRERA-IBARRA HUGO
Published: March 2004

An n-string tangle (B3,T) is a 3-ball B3 which contains n properly embedded arcs T={ti}, it is called rational if there is a homeomorphism of pairs from (B3,T) to (D,P)×I where D is the unit disk, P is any set of n points in the interior of D and I is the unit interval. In this article we extend the classification of the 3-braid group, [Formula: see text], obtained by using Kauffman bracket polynomial, to other families of rational 3-tangles.
A FORMULA FOR THE A-POLYNOMIAL OF TWIST KNOTS
Authors: HOSTE JIM , SHANAHAN PATRICK D.
Published: March 2004

The fundamental group of a 2-bridge knot has a particularly nice presentation, having only two generators and a single relation. For certain families of 2-bridge knots, such as the torus knots, or the twist knots, the relation takes on an especially simple form. Exploiting this form, we derive a formula for the A-polynomial of twist knots. Our methods extend to at least one other infinite family of (non-torus) 2-bridge knots. Using these formulae we determine the associated Newton polygons. We further prove that the A-polynomials of twist knots are irreducible.
ON JONES' PLANAR ALGEBRAS
Authors: KODIYALAM VIJAY , SUNDER V. S.
Published: March 2004

We show that a certain natural class of tangles 'generate the collection of all tangles with respect to composition'. This result is motivated by, and describes the reasoning behind, the 'uniqueness assertion' in Jones' theorem on the equivalence between extremal subfactors of finite index and what we call 'subfactor planar algebras' here. This result is also used to identify the manner in which the planar algebras corresponding to M⊂M1 and Nop⊂Mop are obtained from that of N⊂M.

Our results also show that 'duality' in the category of extremal subfactors of finite index extends naturally to the category of 'general' planar algebras (not necessarily finite-dimensional or spherical or connected or C*, in the terminology of Jones).
UNKNOTTING OF PSEUDO-RIBBON n-KNOTS
Authors: YOSHIDA KYOUHEI
Published: March 2004

Let K be a classical knot in ℝ3. We can deform the diagram of K to that of a trivial knot by changing the overcrossings and undercrossings at some double points of the diagram of K. We consider the same problem for higher dimensinal knots. Let n≥2 and π:ℝn+2=ℝn+1×ℝ→ℝn+1 denote the natural projection map. A pseudo-ribbon n-knot is an n-knot f:Sn→ℝn+2 such that the self-intersection set of π◦f:Sn→ℝn+1 consists of only double points and is homeomorphic to a disjoint union of (n-1)-spheres. We prove that for n≠3,4, the projection (π◦f)(Sn)⊂ℝn+1 of any pseudo-ribbon n-knot f is the projection of a trivial n-knot.
Extreme coefficients of Jones polynomials and graph theory
Authors: Manchón P. M. G.
Published: March 2004

We find families of prime diagrams of knots with arbitrary extreme coefficients in their Jones polynomials. Some graph theory is presents in connection with this problem, generalizing ideas by Yongju Bae and Morton [4] and giving a positive answer to a question in their paper.
AN EXPANSION OF THE JONES REPRESENTATION OF GENUS 2 AND THE TORELLI GROUP II
Authors: KASAHARA YASUSHI
Published: March 2004

We continue to study the algebraic property of the linear representation of the mapping class group of a closed oriented surface of genus 2 constructed by V. F. R. Jones. We consider the perturbation of the representation at the involved parameter t=1. This perturbation naturally induces a filtration on the Torelli group which is coarser than its lower central series. We present some results on the structure of the associated graded quotients. Our arguments follow the same line of our previous paper which dealt with the perturbation at t=-1. However, the obtained results may still suggest a new aspect of the representation.
A SURGERY PROOF OF BING'S THEOREM CHARACTERIZING THE 3-SPHERE
Authors: EISERMANN MICHAEL
Published: March 2004

A classical theorem of R. H. Bing states that a closed connected 3-manifold M is homeomorphic to the 3-sphere if and only if every knot in M is contained in a 3-ball. We give a simple proof of this characterization based on the surgery presentation of 3-manifolds.
A Viral Aetiology for Breast Cancer: Time to Re-Examine the Postulate
Authors: Mant Christine , Hodgson Shirley , Hobday Richard , D’Arrigo Corrado , Cason John
Published: March 2004

Despite decades of research, no aetiologic factor(s) for human breast cancer has been identified and the search for a causal agent has all but been abandoned during the past thirty years. Over 60 years ago, it was demonstrated that breast tumours in mice are caused by an oncornavirus, murine mammary tumour virus (MMTV). Whilst many at that time postulated a similar virus might be the causative agent of human breast cancer, genetic evidence was difficult to obtain primarily because of the occurrence of endogenous human retrovirus (HER) sequences within the human genome that share extensive regions of nucleotide homology with MMTV. Recently, there has been a resurgence of interest in the possibility that a significant proportion of human breast cancers may be caused by viral infections. Two candidate viruses have been proposed, a human retroviral analogue of MMTV (which differs significantly in sequence and characteristics from HERs) and, the Epstein-Barr virus (γ-herpes virus). These two viruses have been reported to occur in up to 37 and 50% of breast cancer cases, respectively. Here we present the background to the infectious hypothesis for the aetiology of breast cancer and review recent findings.
Increased Susceptibility of Herpes simplex Virus-1 Growth in Phytohemagglutinin-Activated T Lymphocytes Caused by Upregulation of Herpesvirus Entry Mediator A mRNA Expression
Authors: Chimma Phattamawan , Chirathaworn Chintana , Bhattarakosol Parvapan
Published: March 2004

Objectives: To study herpes simplex virus (HSV) growth in human T lymphocytes (Jurkat cells) with and without phytohemagglutinin (PHA) activation and to investigate the possible mechanism of viral growth. Methods: The levels of HSV-1 production and adsorption were determined by plaque titration assay. The number of HSV-1-infected cells was assayed using flow cytometry. The expression of herpesvirus entry mediator A (HveA) mRNA was detected by RT-PCR. Results: HSV-1 production as well as the number of HSV-1-infected Jurkat cells were enhanced after the cells were activated by PHA. Moreover, the amount of viral entry was demonstrated to increase in PHA-activated cells. An increase in HveA mRNA was observed in PHA-activated Jurkat cells. Conclusions: We found that HSV-1 can replicate in human T lymphocytes, and the replication was increased following PHA activation. This finding may be due to an increase in viral entry via HveA receptor.
Sustained Negativity for HCV-RNA over 24 or More Months by Long-Term Interferon Therapy Correlates with Eradication of HCV in Patients with Hepatitis C Virus Genotype 1b and High Viral Load
Authors: Arase Yasuji , Suzuki Fumitaka , Tsubota Akihito , Suzuki Yoshiyuki , Saitoh Satoshi , Kobayashi Masahiro , Akuta Norio , Someya Takashi , Hosaka Tetsuya , Kobayashi Mariko , Sezaki Hitomi , Ikeda Kenji , Kumada Hiromitsu
Published: March 2004

Objective: We assessed whether sustained negativity for HCV-RNA over 24 or more months by long-term interferon (IFN) therapy correlates with eradication of HCV in patients with hepatitis C virus genotype 1b and high viral load or not. Methods: The number of patients with HCV-genotype 1b and high viral load exceeding 1 Meq/ml who received 6 MU of natural IFN-α daily for 2–8 weeks, followed by three times/week for 16–22 weeks and negativity for HCV-RNA during IFN administration was 403. Forty-one of 403 patients received 6 MU of natural IFN-α three times/week for more than 18 months after the initial IFN therapy (long-term-IFN-group). Three hundred and two patients did not receive any IFN treatment for 6 months after the termination of the 6-month course (6-month-IFN-group). Sustained virological response (SVR) was defined as negative HCV-RNA at both 3 and 6 months after the completion of IFN therapy. Results: SVR was noted in 73.2% (30/41) of long-term-IFN-group and 18.2% (55/302) of 6-month-IFN-group. Multivariate analysis showed that long-term IFN therapy was the most significant contributor to SVR (p < 0.0001). Conclusion: Sustained negativity of HCV-RNA for 24 or more months by long-term IFN therapy correlated with SVR in patients with genotype 1b and high viral load.
Sex- and Age-Specific Carriers of Hepatitis B and C Viruses in Japan Estimated by the Prevalence in the 3,485,648 First-Time Blood Donors during 1995–2000
Authors: Tanaka Junko , Kumagai Junko , Katayama Keiko , Komiya Yutaka , Mizui Masaaki , Yamanaka Retsuji , Suzuki Kou , Miyakawa Yuzo , Yoshizawa Hiroshi
Published: March 2004

Objective: Carriers of hepatitis B virus (HBV) and hepatitis C virus (HCV) in Japan were estimated on a national basis. Methods: Sera from the first-time blood donors aged 16–64 years in eight jurisdictions of the Japanese Red Cross Blood Center during 1995–2000 were tested for hepatitis B surface antigen (HBsAg) and antibody to HCV (anti-HCV). Viremia with HCV was estimated to be present in 70% of donors with anti-HCV. Results: HBsAg was detected in 22,018 of 3,485,648 (0.63%) blood donors including 12,990 of 1,780,149 (0.73%) men and 9,028 of 1,705,499 (0.53%) women, and anti-HCV in 17,010 (0.49%) including 8,504 (0.48%) men and 8,506 (0.50%) women. Multiplying the carrier rate by the population registered in the Census 2000, the total HBV carriers aged 15–65 years were estimated at 967,753 (95% confidence interval 806,760–1,128,745), of whom 571,210 (479,267–663,152) were men and 396,543 (327,494–465,593) were women. Likewise, the total HCV carriers were estimated at 884,954 (95% confidence interval 725,082–1,044,826), of whom 464,363 (377,927–550,799) were men and 420,591 (347,156–494,027) were women. Conclusion: Estimated numbers of HBV and HCV carriers would help plan to prevent the development of hepatocellular carcinoma in Japan.
Human Polyomavirus BK Monitoring by Quantitative PCR in Renal Transplant Recipients
Authors: Merlino Chiara , Bergallo Massimiliano , Giacchino Franca , Daniele Roberta , Bollero Christian , Comune Luciano , Segoloni Giuseppe Paolo , Cavallo Rossana
Published: March 2004

Objective: To study the relation between human polyomavirus BK (BKV) infection and the risk of developing nephropathy, we monthly investigated the BKV load in urine and serum samples from 15 renal transplant recipients during 6 months in relation with immunosuppressive treatment and renal function. Methods: BKV-DNA in serum samples was detected by nested PCR. BKV-DNA in urine and positive serum samples was quantified by a PCR protocol developed in our laboratory. Results: Fifty-three percent of the patients had quantifiable BKV-DNA both in urine and serum samples but there was no relation between viruria and viraemia. Seventy-five percent of the patients on FK506 therapy and 71.4% of those on CyA therapy showed activation of BKV infection. No patients developed interstitial nephritis during the study. In ten patients serum creatinine levels were <2 mg/dl for the whole study, even if 80% presented BKV viruria and/ or viraemia. On the other hand, in 4 patients serum creatinine levels reached higher values, but they were BKV viruria and/or viraemia negative during the study. Conclusions: Our results suggest that viruria and viraemia may reflect independent BKV reactivation in different tissues. The activation of the infection does not seem to be related to the type of immunosuppressive treatment nor to impairment of renal function. To better understand the pathogenetic role of BKV infection in renal transplant recipients further investigations are needed.
The HPV-16 E5 Protein Inhibits TRAIL- and FasL-Mediated Apoptosis in Human Keratinocyte Raft Cultures
Authors: Kabsch Kirsten , Mossadegh Nina , Kohl Annette , Komposch Gerda , Schenkel Johannes , Alonso Angel , Tomakidi Pascal
Published: March 2004

By using raft cultures of the polyclonal HaCaT cell lines stably transfected either with E5 (HaCaT/E5) or the empty vector (HaCaT/pMSG) as reference, we investigated the effect of the human papillomavirus type 16 (HPV-16) E5 protein on apoptosis. In comparison to conventional monolayer cultures this model system allows analysis of apoptosis under more tissue-like conditions by mimicking the stratified organization of a normal surface epithelium. Apoptosis was triggered either by FasL or TRAIL. Execution of the death program was checked at early and late stages by monitoring procaspase-3 cleavage and DNA fragmentation, respectively. Rafts of E5-expressing keratinocytes were completely protected from apoptosis and showed a background of apoptotic cells as low as the untreated cultures. In contrast, the HaCaT/pMSG cultures revealed a dramatic increase in apoptotic cells upon ligand treatment throughout the epithelial compartment. We conclude that the presence of the HPV-16 E5 protein in our tissue-like model prevents FasL- or TRAIL-mediated apoptosis.
Titration of Hepatitis C Virus in Chimpanzees for Determining the Copy Number Required for Transmission
Authors: Katayama Keiko , Kumagai Junko , Komiya Yutaka , Mizui Masaaki , Yugi Hisao , Kishimoto Shinya , Yamanaka Retsuji , Tamatsukuri Shigeru , Tomoguri Tetsushi , Miyakawa Yuzo , Tanaka Junko , Yoshizawa Hiroshi
Published: March 2004

Objective: To determine the copy number of hepatitis C virus (HCV) RNA, determined by nucleic acid amplification test (NAT) for screening blood units in Japan, that can transmit infection to chimpanzees. Methods: Fresh-frozen plasma with markers of HCV infection, as well as inocula pedigreed from 1 of them, were evaluated for the infectious activity in chimpanzees. Results: One unit each (273–282 ml) of fresh-frozen plasma from 2 blood donors or a pool from 13 donors to make a unit, which contained high-titered antibody to HCV but without HCV RNA detectable by NAT, did not infect any of 3 chimpanzees. Two chimpanzees were infected, however, when they were inoculated with 1 ml of serum from a blood donor in the ‘window period’ of HCV infection and containing 7.0 × 106 copies/ml of HCV RNA. The preacute phase serum from 1 of them harvested 7 weeks after the inoculation was titrated in 2 chimpanzees, and an inoculum containing approximately 2 × 101 copies of HCV RNA could transmit infection to both of them. Conclusion: Approximately 20 copies of HCV can transmit infection to recipients, which needs to be taken into consideration in planning the screening of blood units for HCV RNA by NAT. Although the sensitivity of present NAT could be improved further, there would be a limit of it in detecting a low-level HCV RNA in the window period of donors with the infectious capacity in recipients.
CbsT2 from Lactobacillus johnsonii 100-100 Is a Transport Protein of the Major Facilitator Superfamily That Facilitates Bile Acid Antiport
Authors: Elkins Christopher A. , Savage Dwayne C.
Published: March 2004

We previously identified two conjugated bile acid transporters, CbsT1 and CbsT2, in Lactobacillus johnsonii 100-100 and Lactobacillus acidophilus KS-13 that are gene duplicates encoded in tandem with a conjugated bile salt hydrolase (BSH) [Elkins and Savage, J. Bacteriol. 180:4344–4349, 1998; Elkins et al., Microbiology 147: 3403–3412, 2001]. CbsT2 from 100–100 was shown to increase taurocholic acid (TCA) uptake in Escherichia coli; however, higher levels were achieved when an extracellular factor (EF) from 100–100 was present in the assay medium (spent medium from 100–100, pH 4.2). We continued this study here to determine the role of EF in this transport system. Kinetic studies revealed that the previously observed CbsT2- and EF-mediated TCA accumulation is rapid (<15 s) but not saturable, suggesting that EF is limiting. In addition, uptake of TCA by E. coli expressing CbsT2 was insensitive to ionophores, 2,4-dinitrophenol and carbonyl cyanide m-chlorophenylhydrazone, and thus, is independent of the proton motive force. Since BSH converts [24-14C]TCA to [24-14C]cholic acid (CA), we measured net radiolabel uptake in E. coli cells expressing transporter(s) and BSH. Interestingly, such cells accumulated less 14C radiolabel (by approximately half) than cells expressing CbsT2 alone. These data can be explained if CA diffuses out of E. coli through the transporter(s). We, therefore, added exogenous, unlabeled CA to EF-spent media, which under our assay conditions, performed similarly to EF+ culture supernatant in TCA and CA uptake assays. Thus, unlabeled CA (a protonated, neutral lipophile) can partition directly into E. coli cells especially at low pH. These findings were validated in uptake assays with [3H]TCA, which yields [3H]taurine (a hydrophilic moiety) upon hydrolysis by the BSH. Amounts of cell-associated 3H radiolabel remained similar in cells expressing CbsT2 and BSH versus cells expressing only CbsT2, both of which were higher than in cells expressing BSH alone. Our data support a hypothesis that these transporters, which comprise a new subfamily of the major facilitator superfamily, facilitate antiport of TCA and CA.
The Role of Regulators in the Expression of Quorum-Sensing Signals in Pseudomonas aeruginosa
Authors: Fagerlind Magnus G. , Rice Scott A. , Nilsson Patric , Harlén Mikael , James Sally , Charlton Timothy , Kjelleberg Staffan
Published: March 2004

Quorum-sensing systems provide Pseudomonas aeruginosa with a sensitive regulatory mechanism that allows for the induction of several phenotypic genes in a cell density fashion. In this work, a mathematical model of the acylated homoserine lactones regulatory network system in P. aeruginosa has been developed. It is the first integrated model to consider both quorum-sensing systems. The model has allowed us to disentangle the complex behavior exhibited by the system as the concentration of extracellular OdDHL is increased. At either low or high levels of extracellular OdDHL, the bacterium remains in an uninduced or induced state, respectively. At moderate levels, the behavior is characterized by several states. Here, the bacteria can switch suddenly from an uninduced to an induced phenotype in response to small changes in the concentration of extracellular OdDHL. Additionally, we have been able to address the roles of RsaL and Vfr as regulators of the quorum-sensing system. An important result from this analysis suggests that RsaL will increase the concentration of extracellular OdDHL required to induce the system, and it is a key regulator of the inhibition of the quorum-sensing system under low cell densities. Most importantly, our results suggest that Vfr has strong regulatory effects on the system as an increased affinity between the LasR/OdDHL complex, and the lasR promoter leads to significant qualitative changes in induction patterns. We also show experimental data that demonstrate that Vfr is required for signal production in the early phase of growth, but that in the latter stages of growth, the vfr mutant is able to synthesize wild-type levels of signal.
A Global Approach to Identify Novel Broad-Spectrum Antibacterial Targets among Proteins of Unknown Function
Authors: Zalacain Magdalena , Biswas Sanjoy , Ingraham Karen A. , Ambrad Jennifer , Bryant Alexander , Chalker Alison F. , Iordanescu Serban , Fan Jing , Fan Frank , Lunsford R. Dwayne , O’Dwyer Karen , Palmer Leslie M. , So Chi , Sylvester Daniel , Volker Craig , Warren Patrick , McDevitt Damien , Brown James R. , Holmes David J. , Burnham Martin K.R.
Published: March 2004

Attempted allelic replacement of 144 Streptococcus pneumoniae open reading frames of previously uncharacterized function led to the identification of 36 genes essential for growth under laboratory conditions. Of these, 14 genes (obg, spoIIIJ2, trmU, yacA, yacM, ydiC, ydiE, yjbN, yneS, yphC, ysxC, ytaG, yloI and yxeH4) were also essential in Staphylococcus aureus and Haemophilus influenzae or Escherichia coli, 2 genes (yrrK and ydiB) were only essential in H. influenzae as well as S. pneumoniae and 8 genes were necessary for growth of S.pneumoniae and S. aureus and did not have a homolog in H. influenzae(murD2, ykqC, ylqF, yqeH, ytgP, yybQ) or were not essential in that organism (yqeL, yhcT). The proteins encoded by these genes could represent good targets for novel antibiotics covering different therapeutic profiles. The putative functions of some of these essential proteins, inferred by bioinformatic analysis, are presented. Four mutants, with deletions of loci not essential for in vitro growth, were found to be severely attenuated in a murine respiratory tract infection model, suggesting that not all targets for antibacterial therapeutics are revealed by simple in vitro essentiality testing. The results of our experiments together with those collated from previously reported studies including Bacillus subtilis, E. coli and Mycoplasma sp. demonstrate that gene conservation amongst bacteria does not necessarily indicate that essentiality in one organism can be extrapolated to others. Moreover, this study demonstrates that different experimental procedures can produce apparently contradictory results.
Contact Cheilitis – A Review
Authors: Goh C.L.
Published: March 2004

Contact dermatitis is a common cause of eczematous cheilitis. In a Singapore series, allergic contact dermatitis is commoner than irritant contact dermatitis. More females are affected than males. Eczematous cheilitis usually presents in the 3rd and 4th decades of life. Eczematous cheilitis tends to occur among office workers and professionals (50.5%). This is probably due to the more frequent use of cosmetics and lip preparations among office workers compared to ‘blue collar’ workers. Irritant contact cheilitis is often seen in individuals with an underlying endogenous tendency to eczema, e.g. atopic dermatitis. Contact irritants include lip cosmetics, toothpastes and dentrifices. In the early 1990s, tartar control (pyrophosphates) toothpastes were reported to cause outbreaks of irritant contact dermatitis on the lips and peri-oral skin. Other irritants include traditional Chinese medicines. Allergic contact cheilitis occurs from lip cosmetics, toothpastes and medicaments. Allergic contact cheilitis accounted for 35% of eczematous cheilitis presenting at the Singapore clinic. The commonest cause of allergic contact cheilitis was lip cosmetics. They include lipsticks, lip balms and other cosmetic preparations. In Singapore, ricinoleic acid present in lipsticks accounted for about 10% of all cases of allergic contact dermatitis. Other allergens include other lipstick ingredients, sunscreen agents, toothpaste ingredients, colophony in dental floss and toothpicks, nail varnish, cosmetics and nickel in the mouthpiece of a flute. Recently sunscreens have become a common sensitizer in lip cosmetics. Other allergens include fragrance, balsam of Peru, lanolin and flavourings (strawberry and vanilla). Toothpastes are the next most common cause of allergic contact cheilitis. Dentrifices and dental prostheses have been reported to cause allergic contact dermatitis. Diagnostic clues have to be obtained from a careful history which includes a review of oral rinses, toothpastes, cleansers, mouthwashes, dentrifices, denture materials, chewing gum and lipsticks used by the patient. Patch testing with these products is essential for investigating the possible cause of allergic contact cheilitis. However, there is a group of patients with troublesome cheilitis, who are often severely affected, but in whom the cause of the cheilitis remains obscure. This group may represent patients with endogenous cheilitis or factitious cheilitis.
Methyldibromoglutaronitrile: An Increasingly Important Allergen in the UK
Authors: Ramlogan D. , Basketter D.A. , Beck M.H.
Published: March 2004

Methyldibromoglutaronitrile (MDBGN) was introduced to the European market in 1985, as a preservative for cosmetics, toiletries and industrial products. Since its introduction 17 years ago, studies both in Europe and North America have highlighted it as an increasing new allergen especially in cosmetics. In industry, as MDBGN supersedes isothiazolinones in a wide range of products, its emergence as an important allergen in occupational contact dermatitis becomes more apparent. Dermatologists in the UK need to be aware of this rising new allergen and that the dermatitis can affect not only the head and neck region but also the perianal skin or hands when due to cosmetics, toiletries or industrial products, respectively.
Xerotic Skin of the Elderly: A Summer versus Winter Comparison Based on Biophysical Measurements
Authors: Andersen F. , Andersen K.H. , Kligman A.M.
Published: March 2004

Background: Xerosis, a well-known problem in the elderly part of the population, is often exacerbated in winter with negative effects on daily life. Objective: To describe differences in stratum corneum function of the lower legs in winter compared to summer using objective biometric methods. Methods: The following techniques were utilized: colorimetry, evaporimetry, laser Doppler perfusion imaging, sticky slides (D-Squames®) and corneometry. The reaction to a 24-hour patch test with sodium lauryl sulfate, burning to chloroform:methanol and the whealing response to dimethylsulfoxide were also studied. Results: In winter, the stratum corneum had a looser structure and a diminished barrier function with an increased neurosensory reactivity. Conclusion: The results suggest that the exacerbation of xerosis in the winter is accompanied by structural changes in the stratum corneum, making it looser and more permeable to chemical irritants with a heightened response to neurosensory stimuli.
AISI 316L Stainless-Steel Ear Piercing Post Assembly Does Not Cause Dermatitis in Nickel-Sensitive Subjects
Authors: Ingber Arieh , Hershko Klilah , Horev Liran
Published: March 2004

Twenty-three female and 2 male subjects, documented to be sensitive to nickel by history and diagnostic patch testing, were pierced with American Iron Steel Institute (AISI) 316L stainless-steel ear piercing post assemblies (The Ear Piercing Manufacturers of Europe, UK), AISI 316L having a specification that includes a nickel content of between 10 and 14%. After piercing, the subjects were examined on days 7, 14, 30 and 42. Seven of the ear piercing post assemblies collected at random from the subjects at the end of the study and 10 unused post assemblies selected at random were analysed for nickel content and release. None of the nickel-sensitive patients showed signs of nickel dermatitis during the study. The nickel content of the ear piercing post assemblies collected from patients was reported as being between 11.5 and 12.9%, and the calculated rate of nickel release was below the detection limit of the method, thus recorded at <0.05 µg/cm2/week. By comparison, the nickel content of the unused post assemblies was reported to be between 9.93 and 10.5%, and the calculated rate of nickel release was between 0.11 and 0.21 (mean: 0.15) µg/cm2/week. These results suggest that the AISI 316L stainless-steel ear piercing post assemblies do not elicit adverse reactions to nickel in previously sensitized subjects.
Hypertrophic Lichenoid Eruption Caused by Exposure to Colour Film Developer Used for Motion Picture Film
Authors: Thai Keng-Ee , Freeman Susi
Published: March 2004

Colour film developers based upon substituted phenylene diamines have been a known cause of occupational allergic contact dermatitis (ACD) and lichenoid eruptions. These reactions are well documented in patients involved in the developing of colour photography film. It has been suggested that lichenoid eruptions evolve from ACD. We describe a patient who presented with an eruption identical to lichen planus soon after commencing work as a technician in a motion-picture-film-processing facility. There was no history of a preceding ACD. Patch testing identified sensitivity to Kodak colour developer (CD-2) used for motion picture film, with which he worked on a daily basis.
Flux of a Nickel(II) Salt versus a Nickel(II) Soap across Human Skin in vitro
Authors: Hostýnek J.J.
Published: March 2004

Background: Contrary to in vitro data on skin diffusivity of nickel salts indicating slow rates of diffusion, contact allergy to nickel among the general population is frequent, indicating facile skin penetration. Objective: To demonstrate that the preferred diffusion of a lipophilic oxidation product of nickel formed in contact with the skin follows the multilamellar lipid region which envelops the corneocytes. Method: Diffusion of nickel chloride was compared with that of the lipophilic nickel soap, the dioctanoate. Results: The dioctanoate soap showed a significantly lower rate of diffusion (Kp = 1.4 × 10–3 ± 5.7 × 10–4 cm/h) than the chloride salt (Kp = 9.8 × 10–3 ± 4.8 × 10–4 cm/h), with a relatively high level of nickel retained in the tissue. Conclusions: (a) The molecular volume of the nickel dioctanoate overrides the effect of compound polarity; (b) the rates of diffusion measured through dermatomed skin are higher than those heretofore measured through full-thickness skin, epidermal tissue or stratum corneum; (c) both the nickel salt and soap appear to diffuse primarily via appendages; (d) the cause for the pronounced immune response to nickel in contact with the skin appears to lie in amounts retained in the viable skin strata; (e) skin from a young donor appears more permeable to nickel compounds than skin from an older source stemming from the same anatomical site.
Does Rbmy have a role in sperm development in mice?
Authors: Szot M. , Grigoriev V. , Mahadevaiah S.K. , Ojarikre O.A. , Touré A. , von Glasenapp E. , Rattigan Á. , Turner J.M.A. , Elliott D.J. , Burgoyne P.S.
Published: March 2004

The Yd1 deletion in mice removes most of the multi-copy Rbmy gene cluster that is located adjacent to the centromere on the Y short arm (Yp). XYd1 mice develop as females because Sry is inactivated, probably because it is now juxtaposed to centromeric heterochromatin. We have previously produced XYd1Sry transgenic males and found that they have a substantially increased frequency of abnormal sperm. Staining of testis sections with a polyclonal anti-RBMY antibody appeared to show a marked decrease of RBMY protein in the spermatids of XYd1Sry males compared to control males, which led us to suggest that this may be responsible for the increase in sperm anomalies. In the current study we sought to determine whether augmenting Rbmy expression specifically in the spermatids of XYd1Sry males would ameliorate the sperm defects. An expressing Rbmy transgene driven by the spermatid-specific mouse protamine 1 promotor (mP1Rbmy) was therefore introduced into XYd1Sry males. This failed to reduce the frequency of abnormal sperm. In the course of this study, a new RBMY antibody was generated that, in contrast to the original antibody, failed to detect RBMY in spermatid stages by immunostaining. The lack of RBMY was confirmed by western blotting of lysates from purified round spermatids and elongating spermatids. The implications of these results for the proposed role for RBMY in sperm development are discussed.
The actin-based motor myosin Va is a component of the acroplaxome, an acrosome-nuclear envelope junctional plate, and of manchette-associated vesicles
Authors: Kierszenbaum A.L. , Rivkin E. , Tres L.L.
Published: March 2004

Protein and vesicle cargos can be mobilized during spermiogenesis by intramanchette transport utilizing microtubule-based protein motors (kinesins and dyneins). However, actin-based unconventional myosin motors may also play a significant role in targeting vesicle cargos to subcellular compartments during sperm development. Here we report that myosin Va, an actin-based motor protein, is a component of the acroplaxome of rodent spermatids. The acroplaxome is an F-actin/keratin-containing scaffold plate with a marginal ring fastening the caudal recess of the developing acrosome to the nuclear envelope during spermatid nuclear shaping. In contrast to the acroplaxome, fluorescently labeled phalloidin does not produce an obvious F-actin signal in the manchette. However, immunogold electron microscopy detects moderate but specific β-actin immunoreactivity along interconnected tube-like bundles of manchette microtubules. We also show that the membrane of vesicles co-fractionated with intact manchettes by sucrose gradient ultracentrifugation display immunogold-labeled myosin Va. Myosin Va vesicle localization is known to correlate with Rab proteins, monomeric GTPases of the Ras superfamily which recruit myosin Va/VIIa motor proteins through intermediate proteins. RT-PCR analysis demonstrates that transcripts for Rab27a and Rab27b and Slac2-c (a protein that links Rab27a/b to myosin Va/VIIa) are expressed in testis. These results indicate that two independent cytoskeletal tracks, F-actin in the acroplaxome and presumably in the manchette, and manchette microtubules, may facilitate short-range (from the Golgi to the acrosome) and long-range (from the manchette to the centrosome and axoneme) mobilization of appropriate cargos during spermiogenesis.
Inhibition of lactate dehydrogenase C4 (LDH-C4) blocks capacitation of mouse sperm in vitro
Authors: Duan C. , Goldberg E.
Published: March 2004

Lactate dehydrogenase C4 (LDH-C4) is a tissue-specific enzyme in the mammalian testis and the only lactate dehydrogenase isozyme of sperm. Inhibitors of LDH activity were used to determine whether this enzyme plays a role in sperm capacitation, the acrosome reaction and/or fertilization. Oxamate or its derivative was used to inhibit sperm LDH activity in a medium promoting capacitation. Complete inhibition of LDH activity blocked capacitation. This effect could be reversed partially by the addition of dbcAMP or pentoxifylline to the culture medium. Western blotting showed that oxamate and N-isopropyl oxamate inhibited the tyrosine phosphorylation of proteins during the sperm capacitation process. Presumably, glycolysis is the primary energy pathway for sperm metabolism. The oxidation of reduced NAD with the conversion of pyruvate to lactate by LDH provides ATP necessary for protein kinase A (PKA) activity. Our data indicate that LDH-C4 plays an important metabolic role in sperm capacitation.
N-Acetylglucosamine – An Osmotic Solute for Peritoneal Dialysis without Inducing Hyperinsulinemia
Authors: Bręborowicz A. , Połubińska A. , Simon M. , Tam P. , Wu G.
Published: March 2004

Methods: N-Acetylglucosamine (NAG) was compared to glucose as an osmotic solute during peritoneal dialysis in rats. The effect of the tested solutes on blood glucose and insulin levels during dialysis was evaluated. Results: During 6-hour exchange with NAG (220 mmol/l) solution, the dialysate volume was higher than in rats dialyzed with fluid containing glucose (220 mmol/l; GLU: 34.5 ± 1.7 vs. 32.8 ± 1.1 ml, respectively; p < 0.05). The peritoneal permeability to protein (D/S × 1,000) was lower in the NAG group (9.7 ± 2.5 vs. 16.3 ± 5.6 in GLU; p < 0.02). Dialysis with GLU-based solution resulted in hyperglycemia up to 180 ± 39 mg/dl; in the NAG group the increase in the blood glucose level was moderate (up to 91 ± 9 mg/dl; p < 0.001). Dialysis with GLU fluid caused an increase in blood insulin level by 53.2 ± 62.4 pmol/l, whereas the insulin blood concentration in NAG-treated animals was increased by 5.0 ± 5.4 pmol/l (p < 0.001). Conclusions: NAG is more effective than GLU osmotic solute during peritoneal dialysis and it reduces peritoneal permeability to protein. Dialysis with NAG results in lower hyperglycemia and hyperinsulinemia, both effects are favorable in diabetic peritoneal dialysis patients.
Modulation of Polymorphonuclear Leukocyte Apoptosis in the Critically Ill by Removal of Cytokines with Continuous Hemodiafiltration
Authors: Hirano Takeshi , Hirasawa Hiroyuki , Oda Shigeto , Shiga Hidetoshi , Nakanishi Kazuya , Matsuda Ken-ichi , Nakamura Masataka , Asai Takayoshi , Kitamura Nobuya
Published: March 2004

Delay of polymorphonuclear leukocyte (PMN) apoptosis caused by hypercytokinemia is considered to be a potential cause of tissue damage and resultant organ failure. We evaluated whether continuous hemodiafiltration using a polymethylmethacrylate membrane hemofilter (PMMA-CHDF), which can remove cytokines in the circulating blood, can modulate apoptosis in peripheral blood neutrophils and thereby reduce tissue damage and organ dysfunction in 25 critically ill patients. Following the completion of a 3-day PMMA-CHDF session, serum cytokine levels were significantly decreased and the percentage of apoptotic PMNs was significantly increased. A significant correlation was observed between the PMMA-CHDF-induced increase in the percentage of apoptotic PMNs and the degree of decrease in the serum interleukin-6 level. A significant correlation was also found between the increase in the percentage of apoptotic PMNs and improvement in sequential organ failure assessment score following PMMA-CHDF. These results suggest that PMMA-CHDF in critically ill patients with hypercytokinemia and concomitant delay in apoptosis of PMNs can alleviate the delay of PMN apoptosis through the removal of serum cytokines and thus may result in avoidance of organ dysfunction.
Development of a Protamine Hollow-Fiber Device for Extracorporeal Heparin Removal
Authors: Liang Jun F. , Emregul Emel , Yang Victor C.
Published: March 2004

Protamine was covalently coupled to a cellulose hollow fiber (cuprophan membrane) through epichlorohydrin-activated hydroxyl groups on the hollow fiber. An immobilization efficiency of as much as 15 mg protamine/g fiber could be achieved under optimal reacting conditions. Compared to a protamine hollow-fiber device produced using cyanogen bromide as an activator, the protamine hollow-fiber device using epichlorohydrin as an activator shows very high resistance to hydrolysis. Both in vitro and in vivo experiments showed that such a protamine hollow-fiber device had high heparin-removal capacity and efficiency, suggesting that this device may be suitable for various clinical applications in extracorporeal heparin removal.
Nitric Oxide Synthetic Capacity in Relation to Dialysate Temperature
Authors: Beerenhout Charles H. , Noris Marina , Kooman Jeroen P. , Porrati Francesca , Binda Elena , Morigi Marina , Bekers Otto , van der Sande Frank M. , Todeschini Marta , Macconi Daniela , Leunissen Karel M.L. , Remuzzi Giuseppe
Published: March 2004

Background: During hemodialysis, vascular reactivity is impaired, which can be corrected by lowering dialysate temperature. It has also been shown that nitric oxide (NO) is related to intradialytic hypotension. As NO synthesis may be temperature-dependent, this study addressed the influence of dialysate temperature on the NO synthetic capacity of plasma. Methods: NO synthetic capacity was studied during hemodialysis with a dialysate temperature of 37.5°C (dialysis-37.5°C) and programmed extracorporeal blood cooling (cool dialysis; Blood Temperature Monitor; Fresenius C) in 12 stable patients. NO synthetic capacity was assessed ex vivo by [3H]L-citrulline formation from [3H]L-arginine in cultured endothelial cells after incubation with plasma samples obtained during the respective sessions. Results: Core temperature decreased (–0.32 ± 0.10°C) and energy transfer rate was significantly lower (–27.5 ± 2.8 W; p < 0.05) during cool dialysis compared to dialysis-37.5°C (0.19 ± 0.06°C and –0.8 ± 1.2 W respectively; p < 0.05). Systolic blood pressure decreased during dialysis-37.5°C (–19 ± 4 mm Hg; p < 0.05), but not during cool dialysis (–6 ± 5 mm Hg). NO synthetic capacity increased during dialysis-37.5°C (55.5 ± 9.3 to 73.5 ± 10.2 pmol/105 cells; p < 0.05), in contrast to cool dialysis (67.3 ± 11.1 to 66.2 ± 10.8 pmol/105 cells). Conclusion: The stimulatory effect of uremic plasma on endothelial NO synthesis was augmented during dialysis-37.5°C but not during cool dialysis.