bluuebunny/crossref_metadata_2025 huggingface dataset:
Hermite and Hermite–Fejér interpolation for Stieltjes polynomials
Authors: Jung H.
Published: February 2006

Let

w

λ

(
x
)
:=
(
1
−

x
2

)

λ
−
1

/

2

w_{\lambda }(x):=(1-x^2)^{\lambda -1/2}

and

P
n

(
λ
)

P_n^{(\lambda )}

be the ultraspherical polynomials with respect to

w

λ

(
x
)

w_{\lambda }(x)

. Then we denote by

E

n
+
1

(
λ
)

E_{n+1}^{(\lambda )}

the Stieltjes polynomials with respect to

w

λ

(
x
)

w_{\lambda }(x)

satisfying
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="StartLayout 1st Row integral Subscript negative 1 Superscript 1 Baseline w Subscript lamda Baseline left-parenthesis x right-parenthesis upper P Subscript n Superscript left-parenthesis lamda right-parenthesis Baseline left-parenthesis x right-parenthesis upper E Subscript n plus 1 Superscript left-parenthesis lamda right-parenthesis Baseline left-parenthesis x right-parenthesis x Superscript m d x StartLayout Enlarged left-brace 1st Row 1st Column equals 0 comma 2nd Column a m p semicolon 0 less-than-or-equal-to m greater-than n plus 1 comma 2nd Row 1st Column not-equals 0 comma 2nd Column a m p semicolon m equals n plus 1 period EndLayout EndLayout">

∫

−
1

1

w

λ

(
x
)

P
n

(
λ
)

(
x
)

E

n
+
1

(
λ
)

(
x
)

x
m

d
x

{

=
0
,

a
m
p
;
0
≤
m
>
n
+
1
,

≠
0
,

a
m
p
;
m
=
n
+
1.

\begin{eqnarray*} \int _{-1}^1 w_{\lambda }(x) P_n^{(\lambda )}(x)E_{n+1}^{(\lambda )}(x) x^m dx \begin {cases} =0, & 0 \le m > n+1,\\ \neq 0, & m=n+1. \end{cases} \end{eqnarray*}

In this paper, we show uniform convergence of the Hermite–Fejér interpolation polynomials

H

n
+
1

[
⋅
]

H_{n+1}[\cdot ]

and

H

2
n
+
1

[
⋅
]

{\mathcal H}_{2n+1}[\cdot ]

based on the zeros of the Stieltjes polynomials

E

n
+
1

(
λ
)

E_{n+1}^{(\lambda )}

and the product

E

n
+
1

(
λ
)

P
n

(
λ
)

E_{n+1}^{(\lambda )}P_n^{(\lambda )}

for

0
≤
λ
≤
1

0 \le \lambda \le 1

and

0
≤
λ
≤
1

/

2

0 \le \lambda \le 1/2

, respectively. To prove these results, we prove that the Lebesgue constants of Hermite–Fejér interpolation operators for the Stieltjes polynomials

E

n
+
1

(
λ
)

E_{n+1}^{(\lambda )}

and the product

E

n
+
1

(
λ
)

P
n

(
λ
)

E_{n+1}^{(\lambda )}P_n^{(\lambda )}

are optimal, that is, the Lebesgue constants

‖

H

n
+
1

‖

∞

(
0
≤
λ
≤
1
)

\|H_{n+1}\|_{\infty }(0 \le \lambda \le 1)

and

‖

H

2
n
+
1

‖

∞

(
0
≤
λ
≤
1

/

2
)

\|{\mathcal H}_{2n+1}\|_{\infty } (0 \le \lambda \le 1/2)

have optimal order

O
(
1
)

O(1)

. In the case of the Hermite–Fejér interpolation polynomials

H

2
n
+
1

[
⋅
]

{\mathcal H}_{2n+1}[\cdot ]

for

1

/

2
>
λ
≤
1

1/2 > \lambda \le 1

, we prove weighted uniform convergence. Moreover, we give some convergence theorems of Hermite–Fejér and Hermite interpolation polynomials for

0
≤
λ
≤
1

0 \le \lambda \le 1

in weighted

L
p

L_p

norms.
Computation of the Newton step for the even and odd characteristic polynomials of a symmetric positive definite Toeplitz matrix
Authors: Melman A.
Published: February 2006

We compute the Newton step for the characteristic polynomial and for the even and odd characteristic polynomials of a symmetric positive definite Toeplitz matrix as the reciprocal of the trace of an appropriate matrix. We show that, after the Yule–Walker equations are solved, this trace can be computed in

O

(
n
)

{\mathcal O}(n)

additional arithmetic operations, which is in contrast to existing methods, which rely on a recursion, requiring

O

(

n
2

)

{\mathcal O}(n^2)

additional arithmetic operations.
CM-fields with relative class number one
Authors: Lee Geon-No , Kwon Soun-Hi
Published: February 2006

We will show that the normal CM-fields with relative class number one are of degrees

≤
216

\leq 216

. Moreover, if we assume the Generalized Riemann Hypothesis, then the normal CM-fields with relative class number one are of degrees

≤
96

\leq 96

, and the CM-fields with class number one are of degrees

≤
104

\leq 104

. By many authors all normal CM-fields of degrees

≤
96

\leq 96

with class number one are known except for the possible fields of degree

64
64

or

96
96

. Consequently the class number one problem for normal CM-fields is solved under the Generalized Riemann Hypothesis except for these two cases.
New irrationality measures for 𝑞-logarithms
Authors: Matala-aho Tapani , Väänänen Keijo , Zudilin Wadim
Published: February 2006

The three main methods used in diophantine analysis of

q
q

-series are combined to obtain new upper bounds for irrationality measures of the values of the

q
q

-logarithm function
\[
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="ln Subscript q Baseline left-parenthesis 1 minus z right-parenthesis equals sigma-summation Underscript nu equals 1 Overscript normal infinity Endscripts StartFraction z Superscript nu Baseline q Superscript nu Baseline Over 1 minus q Superscript nu Baseline EndFraction comma StartAbsoluteValue z EndAbsoluteValue less-than-or-slanted-equals 1 comma">

ln

q

⁡
(
1
−
z
)
=

∑

ν
=
1

∞

z

ν

q

ν

1
−

q

ν

,

|

z

|

⩽
1
,

\ln _{q}(1-z)=\sum _{\nu =1}^{\infty }\frac {z^{\nu }q^{\nu }}{1-q^{\nu }}, \qquad |z|\leqslant 1,

\]
when

p
=
1

/

q
∈

Z

∖
{
0
,
±
1
}

p=1/q\in \mathbb {Z}\setminus \{0,\pm 1\}

and

z
∈

Q

z\in \mathbb {Q}

.
General order multivariate Padé approximants for pseudo-multivariate functions
Authors: Cuyt Annie , Tan Jieqing , Zhou Ping
Published: February 2006

Although general order multivariate Padé approximants were introduced some decades ago, very few explicit formulas for special functions have been given. We explicitly construct some general order multivariate Padé approximants to the class of so-called pseudo-multivariate functions, using the Padé approximants to their univariate versions. We also prove that the constructed approximants inherit the normality and consistency properties of their univariate relatives, which do not hold in general for multivariate Padé approximants. Examples include the multivariate forms of the exponential and the

q
q

-exponential functions
\[
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper E left-parenthesis x comma y right-parenthesis equals sigma-summation Underscript i comma j equals 0 Overscript normal infinity Endscripts StartFraction x Superscript i Baseline y Superscript j Baseline Over left-parenthesis i plus j right-parenthesis factorial EndFraction">

E

(
x
,
y
)

=

∑

i
,
j
=
0

∞

x
i

y
j

(
i
+
j
)

!

E\left ( x,y\right ) =\sum _{i,j=0}^\infty \frac {x^iy^j}{\left ( i+j\right ) !}

\]
and
\[
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper E Subscript q Baseline left-parenthesis x comma y right-parenthesis equals sigma-summation Underscript i comma j equals 0 Overscript normal infinity Endscripts StartFraction x Superscript i Baseline y Superscript j Baseline Over left-bracket i plus j right-bracket Subscript q Baseline factorial EndFraction comma">

E
q

(
x
,
y
)

=

∑

i
,
j
=
0

∞

x
i

y
j

[
i
+
j

]
q

!

,

E_q\left ( x,y\right ) =\sum _{i,j=0}^\infty \frac {x^iy^j}{[i+j]_q!},

\]
as well as the Appell function
\[
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper F 1 left-parenthesis a comma 1 comma 1 semicolon c semicolon x comma y right-parenthesis equals sigma-summation Underscript i comma j equals 0 Overscript normal infinity Endscripts StartFraction left-parenthesis a right-parenthesis Subscript i plus j Baseline x Superscript i Baseline y Superscript j Baseline Over left-parenthesis c right-parenthesis Subscript i plus j Baseline EndFraction">

F
1

(
a
,
1
,
1
;
c
;
x
,
y
)

=

∑

i
,
j
=
0

∞

(
a
)

i
+
j

x
i

y
j

(
c
)

i
+
j

F_1\left ( a,1,1;c;x,y\right ) =\sum _{i,j=0}^\infty \frac {\left ( a\right ) _{i+j}x^iy^j}{\left ( c\right ) _{i+j}}

\]
and the multivariate form of the partial theta function
\[
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper F left-parenthesis x comma y right-parenthesis equals sigma-summation Underscript i comma j equals 0 Overscript normal infinity Endscripts q Superscript minus left-parenthesis i plus j right-parenthesis squared slash 2 Baseline x Superscript i Baseline y Superscript j Baseline period">

F

(
x
,
y
)

=

∑

i
,
j
=
0

∞

q

−

(
i
+
j
)

2

/

2

x
i

y
j

.

F\left ( x,y\right ) =\sum _{i,j=0}^\infty q^{-\left ( i+j\right ) ^2/2}x^iy^j.

\]
Sharp precision in Hensel lifting for bivariate polynomial factorization
Authors: Lecerf Grégoire
Published: February 2006

Popularized by Zassenhaus in the seventies, several algorithms for factoring polynomials use a so-called lifting and recombination scheme. Concerning bivariate polynomials, we present a new algorithm for the recombination stage that requires a lifting up to precision twice the total degree of the polynomial to be factored. Its cost is dominated by the computation of reduced echelon solution bases of linear systems. We show that our bound on precision is asymptotically optimal.
A new superconvergent collocation method for eigenvalue problems
Authors: Kulkarni Rekha
Published: February 2006

Here we propose a new method based on projections for the approximate solution of eigenvalue problems. For an integral operator with a smooth kernel, using an interpolatory projection at Gauss points onto the space of (discontinuous) piecewise polynomials of degree

≤
r
−
1

\leq r-1

, we show that the proposed method exhibits an error of the order of

4
r

4r

for eigenvalue approximation and of the order of

3
r

3r

for spectral subspace approximation. In the case of a simple eigenvalue, we show that by using an iteration technique, an eigenvector approximation of the order

4
r

4r

can be obtained. This improves upon the order

2
r

2r

for eigenvalue approximation in the collocation/iterated collocation method and the orders

r
r

and

2
r

2r

for spectral subspace approximation in the collocation method and the iterated collocation method, respectively. We illustrate this improvement in the order of convergence by numerical examples.
A Role for PP1 in the Cdc2/Cyclin B–mediated Positive Feedback Activation of Cdc25
Authors: Margolis Seth S. , Perry Jennifer A. , Weitzel Douglas H. , Freel Christopher D. , Yoshida Minoru , Haystead Timothy A. , Kornbluth Sally
Published: February 2006

The Cdc25 phosphatase promotes entry into mitosis through the removal of inhibitory phosphorylations on the Cdc2 subunit of the Cdc2/CyclinB complex. During interphase, or after DNA damage, Cdc25 is suppressed by phosphorylation at Ser287 (Xenopus numbering; Ser216 of human Cdc25C) and subsequent binding of the small acidic protein, 14-3-3. As reported recently, at the time of mitotic entry, 14-3-3 protein is removed from Cdc25 and S287 is dephosphorylated by protein phosphatase 1 (PP1). After the initial activation of Cdc25 and consequent derepression of Cdc2/CyclinB, Cdc25 is further activated through a Cdc2-catalyzed positive feedback loop. Although the existence of such a loop has been appreciated for some time, the molecular mechanism for this activation has not been described. We report here that phosphorylation of S285 by Cdc2 greatly enhances recruitment of PP1 to Cdc25, thereby accelerating S287 dephosphorylation and mitotic entry. Moreover, we show that two other previously reported sites of Cdc2-catalyzed phosphorylation on Cdc25 are required for maximal biological activity of Cdc25, but they do not contribute to PP1 regulation and do not act solely through controlling S287 phosphorylation. Therefore, multiple mechanisms, including enhanced recruitment of PP1, are used to promote full activation of Cdc25 at the time of mitotic entry.
Cooperation between Snail and LEF-1 Transcription Factors Is Essential for TGF-β1-induced Epithelial-Mesenchymal Transition
Authors: Medici Damian , Hay Elizabeth D. , Goodenough Daniel A.
Published: February 2006

Transforming growth factor beta 1 (TGF-β1) has been shown to induce epithelial-mesenchymal transition (EMT) during various stages of embryogenesis and progressive disease. This alteration in cellular morphology is typically characterized by changes in cell polarity and loss of adhesion proteins such as E-cadherin. Here we demonstrate that EMT is associated with loss of claudin-1, claudin-2, occludin, and E-cadherin expression within 72 h of exposure to TGF-β1 in MDCKII cells. It has been suggested that this expression loss occurs through TGF-β1 in a Smad-independent mechanism, involving MEK and PI3K pathways, which have previously been shown to induce expression of the Snail (SNAI-1) gene. Here we show that these pathways are responsible for loss of tight junctions and a partial loss of E-cadherin. However, our results also demonstrate that a complete loss of E-cadherin and transformation to the mesenchymal phenotype are dependent on Smad signaling, which subsequently stimulates formation of β-catenin/LEF-1 complexes that induce EMT.
Protein Kinase Cζ Attenuates Hypoxia-induced Proliferation of Fibroblasts by Regulating MAP Kinase Phosphatase-1 Expression
Authors: Short Megan D. , Fox Stephanie M. , Lam Ching F. , Stenmark Kurt R. , Das Mita
Published: February 2006

We have previously found that hypoxia stimulates proliferation of vascular fibroblasts through Gαi-mediated activation of ERK1/2. Here, we demonstrate that hypoxia also activates the atypical protein kinase Cζ (PKCζ) isozyme and stimulates the expression of ERK1/2-specific phosphatase, MAP kinase phosphatase-1 (MKP-1), which attenuates ERK1/2-mediated proliferative signals. Replication repressor activity is unique to PKCζ because the blockade of classical and novel PKC isozymes does not affect fibroblast proliferation. PKCζ is phosphorylated upon prolonged (24 h) exposure to hypoxia, whereas ERK1/2, the downstream kinases, are maximally activated in fibroblasts exposed to acute (10 min) hypoxia. However, PKCζ blockade results in persistent ERK1/2 phosphorylation and marked increase in hypoxia-induced replication. Similarly prolonged ERK1/2 phosphorylation and increase in hypoxia-stimulated proliferation are also observed upon blockade of MKP-1 activation. Because of the parallel suppressive actions of PKCζ and MKP-1 on ERK1/2 phosphorylation and proliferation, the role of PKCζ in the regulation of MKP-1 expression was evaluated. PKCζ attenuation reduces MKP-1 expression, whereas PKCζ overexpression increases MKP-1 levels. In conclusion, our results indicate for the first time that hypoxia activates PKCζ, which acts as a terminator of ERK1/2 activation through the regulation of downstream target, MKP-1 expression and thus serves to limit hypoxia-induced proliferation of fibroblasts.
Actin-depolymerizing Protein Adf1 Is Required for Formation and Maintenance of the Contractile Ring during Cytokinesis in Fission Yeast
Authors: Nakano Kentaro , Mabuchi Issei
Published: February 2006

The role of the actin-depolymerizing factor (ADF)/cofilin-family protein Adf1 in cytokinesis of fission yeast cells was studied. Adf1 was required for accumulation of actin at the division site by depolymerizing actin at the cell ends, assembly of the contractile ring through severing actin filaments, and maintenance of the contractile ring once formed. Genetic and cytological analyses suggested that it collaborates with profilin and capping protein in the mitotic reorganization of the actin cytoskeleton. Furthermore, it was unexpectedly found that Adf1 and myosin-II also collaborate in assembling the contractile ring. Tropomyosin was shown to antagonize the function of Adf1 in the contractile ring. We propose that formation and maintenance of the contractile ring are achieved by a balanced collaboration of these proteins.
Interacting Protein Kinases Involved in the Regulation of Flagellar Length
Authors: Erdmann Maja , Scholz Anne , Melzer Inga M. , Schmetz Christel , Wiese Martin
Published: February 2006

A striking difference of the life stages of the protozoan parasite Leishmania is a long flagellum in the insect stage promastigotes and a rudimentary organelle in the mammalian amastigotes. LmxMKK, a mitogen-activated protein (MAP) kinase kinase from Leishmania mexicana, is required for growth of a full-length flagellum. We identified LmxMPK3, a MAP kinase homologue, with a similar expression pattern as LmxMKK being not detectable in amastigotes, up-regulated during the differentiation to promastigotes, constantly expressed in promastigotes, and shut down during the differentiation to amastigotes. LmxMPK3 null mutants resemble the LmxMKK knockouts with flagella reduced to one-fifth of the wild-type length, stumpy cell bodies, and vesicles and membrane fragments in the flagellar pocket. A constitutively activated recombinant LmxMKK activates LmxMPK3 in vitro. Moreover, LmxMKK is likely to be directly involved in the phosphorylation of LmxMPK3 in vivo. Finally, LmxMPK3 is able to phosphorylate LmxMKK, indicating a possible feedback regulation. This is the first time that two interacting components of a signaling cascade have been described in the genus Leishmania. Moreover, we set the stage for the analysis of reversible phosphorylation in flagellar morphogenesis.
Sp2 Localizes to Subnuclear Foci Associated with the Nuclear Matrix
Authors: Moorefield K. Scott , Yin Haifeng , Nichols Teresa D. , Cathcart Christopher , Simmons Steven O. , Horowitz Jonathan M.
Published: February 2006

We have reported that extracts prepared from many human and mouse cell lines show little or no Sp2 DNA-binding activity and that Sp2 has little or no capacity to stimulate transcription of promoters that are activated by Sp1, Sp3, and Sp4. Using an array of chimeric Sp1/Sp2 proteins we showed further that Sp2 DNA-binding activity and trans-activation are each negatively regulated in mammalian cells. As part of an ongoing effort to study Sp2 function and regulation we characterized its subcellular localization in comparison with other Sp-family members in fixed and live cells. We report that 1) Sp2 localizes largely within subnuclear foci associated with the nuclear matrix, and 2) these foci are distinct from promyelocytic oncogenic domains and appear to be stable during an 18-h time course of observation. Deletion analyses identified a 37 amino acid sequence spanning the first zinc-“finger” that is sufficient to direct nuclear matrix association, and this region also encodes a bipartite nuclear localization sequence. A second nuclear matrix targeting sequence is encoded within the Sp2 trans-activation domain. We conclude that Sp2 preferentially associates with the nuclear matrix and speculate that this subcellular localization plays an important role in the regulation of Sp2 function.
Role of LIM Kinases in Normal and Psoriatic Human Epidermis
Authors: Honma Masaru , Benitah Salvador Aznar , Watt Fiona M.
Published: February 2006

We present evidence that LIM kinases can control cell adhesion and compaction in human epidermis. LIMK2 is expressed in the epidermal basal layer and signals downstream of the GTPase Rac1 to promote extracellular matrix adhesion and inhibit terminal differentiation. Conversely, LIMK1 is expressed in the upper granular layers and phosphorylates and inhibits cofilin. Expression of LIMK1 is lost in psoriatic lesions and other skin disorders characterized by lack of cell compaction in the differentiating cell layers. In psoriatic lesions down-regulation of LIMK1 correlates with up-regulation of Myc. Expression of constitutively active cofilin or Myc in reconstituted human epidermis blocks cell compaction. Overexpression of LIMK1 leads to down-regulation of Myc, whereas inhibition of Rho kinase, an upstream activator of LIMK1, stimulates Myc expression. Inhibition of Myc by LIMK1 is via inhibition of Stat3 phosphorylation, because constitutively active cofilin or inhibition of Rho kinase results in Stat3 phosphorylation and increased Myc levels, whereas dominant negative Stat3 abolishes the effect. In conclusion, we have uncovered a novel antagonistic relationship between the LIMK1/phosphocofilin and Myc/Stat3 pathways in the differentiating layers of human epidermis and propose that down-regulation of LIMK1 contributes to one of the pathological features of psoriatic epidermal lesions.
A PDZ-binding Motif as a Critical Determinant of Rho Guanine Exchange Factor Function and Cell Phenotype
Authors: Liu Miaoliang , Horowitz Arie
Published: February 2006

We identified a Rho guanine exchange factor (GEF) expressed as two splice variants, which differ only in either having or lacking a Postsynaptic density 95, Disk large, Zona occludens-1 (PDZ) motif. The PDZ adaptor protein synectin bound the longer splice variant, Syx1, which was targeted to the plasma membrane in a synectin-dependent manner. The shorter variant, Syx2, was diffusely distributed in the cytoplasm. Fluorescence resonance energy transfer (FRET) imaging revealed similar differences between the spatial patterns of active RhoA in Syx1 versus Syx2-expressing cells. Expression of Syx1 augmented endothelial cell (EC) migration and tube formation, whereas Syx2 expression did not. It appears, therefore, that synectin-dependent targeting of Syx is critical to its contribution to these EC functions. Although agonist-stimulated global RhoA activity was similar in Syx1- and Syx2-expressing cells, basal RhoA activity was surprisingly higher in the latter. Out of 23 cell types, we found a significant level of endogenous Syx2 expression only in brain tumor cells, which also exhibited high basal RhoA activity. We found that the activity level of JNK, which mediates transcriptional regulation downstream of RhoA, is elevated in a Syx2-dependent manner in these cells, possibly contributing to their tumorigenicity.
Environmental pollution has sex-dependent effects on local survival
Authors: Eeva Tapio , Hakkarainen Harri , Laaksonen Toni , Lehikoinen Esa
Published: February 2006

Environmental pollutants cause a potential hazard for survival in free-living animal populations. We modelled local survival (including emigration) by using individual mark–recapture histories of males and females in a population of a small insectivorous passerine bird, the pied flycatcher (
Ficedula hypoleuca
) living around a point source of heavy metals (copper smelter). Local survival of
F. hypoleuca
females did not differ between polluted and unpolluted environments. Males, however, showed a one-third higher local-survival probability in the polluted area. Low fledgling production was generally associated with decreased local survival, but males in the polluted area showed relatively high local survival, irrespective of their fledgling number. A possible explanation of higher local survival of males in the polluted area could be a pollution-induced change in hormone (e.g. corticosterone or testosterone) levels of males. It could make them to invest more on their own survival or affect the hormonal control of breeding dispersal. The local survival of males decreased in the polluted area over the study period along with the simultaneous decrease in heavy metal emissions. This temporal trend is in agreement with the stress hormone hypothesis.
Mechanisms of evolutionary change in structural plumage coloration among bluebirds (Sialiaspp.)
Authors: Shawkey Matthew D , Balenger Susan L , Hill Geoffrey E , Johnson L. Scott , Keyser Amber J , Siefferman Lynn
Published: February 2006

Combinations of microstructural and pigmentary components of barbs create the colour displays of feathers. It follows that evolutionary changes in colour displays must reflect changes in the underlying production mechanisms, but rarely have the mechanisms of feather colour evolution been studied. Among bluebirds in the genusSialia, male rump colour varies among species from dark blue to light blue while breast colour varies from blue to rusty. We use spectrometry, transmission electron microscopy and Fourier analysis to identify the morphology responsible for these divergent colour displays. The morphology of blue rump barbs is similar among the three species, with an outer keratin cortex layer surrounding a medullary ‘spongy layer’ and a basal row of melanin granules. A spongy layer is also present in blue breast barbs of mountain bluebirdsSialia currucoidesand in rusty breast barbs of westernSialia mexicanaand eastern bluebirdsSialia sialis. In blue barbs melanin is basal to the spongy layer, but is not present in the outer cortex or spongy layer, while in rusty barbs, melanin is present only in the cortex. The placement of melanin in the cortex masks expression of structural blue, creating a rusty display. Such shifts in microstructures and pigments may be widespread mechanisms for the evolutionary changes in the colours of feathers and other reflective structures across colourful organisms.
The portability of tagSNPs across populations: A worldwide survey
Authors: González-Neira Anna , Ke Xiayi , Lao Oscar , Calafell Francesc , Navarro Arcadi , Comas David , Cann Howard , Bumpstead Suzannah , Ghori Jilur , Hunt Sarah , Deloukas Panos , Dunham Ian , Cardon Lon R. , Bertranpetit Jaume
Published: February 2006

In the search for common genetic variants that contribute to prevalent human diseases, patterns of linkage disequilibrium (LD) among linked markers should be considered when selecting SNPs. Genotyping efficiency can be increased by choosing tagging SNPs (tagSNPs) in LD with other SNPs. However, it remains to be seen whether tagSNPs defined in one population efficiently capture LD in other populations; that is, how portable tagSNPs are. Indeed, tagSNP portability is a challenge for the applicability of HapMap results. We analyzed 144 SNPs in a 1-Mb region of chromosome 22 in 1055 individuals from 38 worldwide populations, classified into seven continental groups. We measured tagSNP portability by choosing three reference populations (to approximate the three HapMap populations), defining tagSNPs, and applying them to other populations independently on the availability of information on the tagSNPs in the compared population. We found that tagSNPs are highly informative in other populations within each continental group. Moreover, tagSNPs defined in Europeans are often efficient for Middle Eastern and Central/South Asian populations. TagSNPs defined in the three reference populations are also efficient for more distant and differentiated populations (Oceania, Americas), in which the impact of their special demographic history on the genetic structure does not interfere with successfully detecting the most common haplotype variation. This high degree of portability lends promise to the search for disease association in different populations, once tagSNPs are defined in a few reference populations like those analyzed in the HapMap initiative.
Short‐term dehydroepiandrosterone treatment increases platelet cGMP production in elderly male subjects
Authors: Martina Valentino , Benso Andrea , Gigliardi Valentina Ramella , Masha Andi , Origlia Carla , Granata Riccarda , Ghigo Ezio
Published: February 2006

Objective  Several clinical and population‐based studies suggest that dehydroepiandrosterone (DHEA) and its sulphate (DHEA‐S) play a protective role against atherosclerosis and coronary artery disease in human. However, the mechanisms underlying this action are still unknown. It has recently been suggested that DHEA‐S could delay atheroma formation through an increase in nitric oxide (NO) production.

Study design and methods  Twenty‐four aged male subjects [age (mean ± SEM): 65·4 ± 0·7 year; range: 58·2–67·6 years] underwent a blinded placebo controlled study receiving DHEA (50 mg p.o. daily at bedtime) or placebo for 2 months. Platelet cyclic guanosine‐monophosphate (cGMP) concentration (as marker of NO production) and serum levels of DHEA‐S, DHEA, IGF‐I, insulin, glucose, oestradiol (E2), testosterone, plasminogen activator inhibitor (PAI)‐1 antigen (PAI‐1 Ag), homocysteine and lipid profile were evaluated before and after the 2‐month treatment with DHEA or placebo.

Results  At the baseline, all variables in the two groups were overlapping. All parameters were unchanged after treatment with placebo. Conversely, treatment with DHEA (a) increased (P < 0·001 vs. baseline) platelet cGMP (111·9 ± 7·1 vs. 50·1 ± 4·1 fmol/106 plts), DHEA‐S (13·6 ± 0·8 vs. 3·0 ± 0·3 µmol/l), DHEA (23·6 ± 1·7 vs. 15·3 ± 1·4 nmol/l), testosterone (23·6 ± 1·0 vs. 17·7 ± 1·0 nmol/l) and E2 (72·0 ± 5·0 vs. 60·0 ± 4·0 pmol/l); and (b) decreased (P < 0·05 vs. baseline) PAI‐1 Ag (27·4 ± 3·8 vs. 21·5 ± 2·5 ng/ml) and low‐density lipoprotein (LDL) cholesterol (3·4 ± 0·2 vs. 3·0 ± 0·2 mmol/l). IGF‐I, insulin, glucose, triglycerides, total cholesterol, HDL cholesterol, HDL2 cholesterol, HDL3 cholesterol, apolipoprotein A1 (ApoA1), apolipoprotein B (ApoB) and homocysteine levels were not modified by DHEA treatment.

Conclusions  This study shows that short‐term treatment with DHEA increased platelet cGMP production, a marker of NO production, in healthy elderly subjects. This effect is coupled with a decrease in PAI‐1 and LDL cholesterol levels as well as an increase in testosterone and E2 levels. These findings, therefore, suggest that chronic DHEA supplementation would exert antiatherogenic effects, particularly in elderly subjects who display low circulating levels of this hormone.
Genetic and environmental determinants of circulating levels of angiogenin in community‐based sample
Authors: Pantsulaia Ia , Trofimov Svetlana , Kobyliansky Eugene , Livshits Gregory
Published: February 2006

Background  Measurement of angiogenin in plasma provides important prognostic and diagnostic information in variety of malignancies and may even correlate with cancer's progression. Nevertheless, nowadays, specific physiological mechanisms of this protein action as well as major factors regulating its circulating levels normally and in pathology are still poorly understood. The main objectives of this study were to examine the contribution of a number of endogenous factors, such as sex, age, body size and genetic effects on the production of angiogenin in apparently healthy individuals, and to assess the correlations in circulating levels between angiogenin and other molecules involved in angiogenesis.

Methods  The plasma levels of angiogenin and each of the additional cytokines [interleukin‐6 (IL‐6), tumour necrosis factor‐α (TNF‐α), transforming growth factor‐β (TGF‐β), macrophage‐colony stimulating factor (M‐CSF), vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), soluble intercellular adhesion molecule‐1 (sICAM)] were determined by enzyme‐linked immunoassay in a large family based sample.

Results  Angiogenin levels were significantly higher in man than in women (360·64 104·04 ng/ml vs. 322·15  100·34 ng/ml, P < 0·01) and significantly correlated with age (P < 0·01) in both sexes. Genetic analysis showed that adjusted for potential covariates, 37·4  7·1% of angiogenin variation was attributable to putative genetic factors. The results of our study revealed that angiogenin concentrations were positively and significantly (P < 0·05) associated with sICAM, IL‐6, TNF‐α and M‐CSF levels in the female cohort.

Conclusions  Our data provide reliable evidence for the substantial role of genetic factors in the determination of the phenotypic variability of angiogenin plasma levels. These findings of our study, including circulating angiogenin reference limits in healthy population and its correlation with angiogenic cytokines, may be of importance in determination of early stages of pathological angiogenesis.
Factors other than glucocorticoids are involved in the osteoblast activity decrease caused by tissue injury
Authors: Olmos J. M. , Amado J. A. , Valero C. , Hernández J. L. , González‐Macías J.
Published: February 2006

Objective  Serum osteocalcin is a marker of bone formation. The concentration of osteocalcin is decreased with tissue injury. As glucocorticoids are known both to be increased in this situation and to diminish serum osteocalcin, we have hypothesized that they could be involved in this decrease.

Design and patients  We compared osteocalcin levels in two groups of patients undergoing abdominal surgery, one receiving thiopental, and the other etomidate, a glucocorticoid synthesis blocker. For comparative reasons, another protein decreased by glucocorticoids (osteoprotegerin) was measured in patients anaesthetized with thiopental.

Measurements  Serum osteocalcin, cortisol and albumin were determined before and over the 24 h following surgery. Serum concentration of osteoprotegerin (OPG) and receptor activator of the nuclear factor κB ligand (RANKL) were also determined before and 24 h after surgery in a third group of nine patients who received thiopental for anaesthetic induction.

Results  Cortisol levels were increased in the thiopental group, whereas, as expected, were decreased in etomidate patients. However, serum osteocalcin concentration decreased in a similar way in both groups. Serum OPG and RANKL levels were within the normal range at baseline and did not significantly change after surgery.

Conclusions  The decrease in serum osteocalcin induced by tissue injury is independent of the increase in cortisol secretion triggered by the latter. In addition, another pharmacologically proven effect of cortisol on bone metabolism, OPG inhibition, could not be demonstrated in the first 24 h following surgery, in spite of the physiological increase in endogenous cortisol secretion taking place in this period.
Parafibromin mutations in hereditary hyperparathyroidism syndromes and parathyroid tumours
Authors: Bradley K. J. , Cavaco B. M. , Bowl M. R. , Harding B. , Cranston T. , Fratter C. , Besser G. M. , da Conceição Pereira M. , Davie M. W. J. , Dudley N. , Leite V. , Sadler G. P. , Seller A. , Thakker R. V.
Published: February 2006

Objective  To investigate two patients with the hyperparathyroidism‐jaw tumour (HPT‐JT) syndrome and three patients with familial isolated hyperparathyroidism (FIHP), together with 31 parathyroid tumours (2 HPT‐JT, 2 FIHP and 27 sporadic) for HRPT2 mutations. The HPT‐JT syndrome and FIHP are autosomal dominant disorders that may be caused by abnormalities of the HRPT2 gene, located on chromosome 1q31.2. HRPT2 encodes a 531 amino acid protein, parafibromin, which interacts with human homologues of the yeast Paf1 complex.

Design  Leukocyte and tumor DNA was used with HRPT2‐specific primers for polymerase chain reaction amplification of the 17 exons and their splice junctions, and the DNA sequences of the polymerase chain reaction products determined.

Results  Three heterozygous germline HRPT2 mutations, two in HPT‐JT and one in FIHP patients, were identified. These consisted of one 1‐bp duplication (745dup1bp), 1 nonsense (Arg234Stop) and 1 missense (Asp379Asn) mutation. One parathyroid tumour from an FIHP patient was demonstrated to harbour a germline deletion of 1 bp together with a somatic missense (Leu95Pro) mutation, consistent with a ‘two‐hit’ model for hereditary cancer. The 27 sporadic benign parathyroid tumours did not harbour any HRPT2 somatic mutations. Six HRPT2 polymorphisms with allele frequencies ranging from 2% to 15% were detected.

Conclusions  Our results have identified three novel HRPT2 mutations (two germline and one somatic). The Asp379Asn mutation is likely to disrupt interaction with the human homologue of the yeast Paf1 complex, and the demonstration of combined germline and somatic HRPT2 mutations in a parathyroid tumour provide further evidence for the tumour suppressor role of the HRPT2 gene.
Associations between liver histology and cortisol secretion in subjects with nonalcoholic fatty liver disease
Authors: Targher Giovanni , Bertolini Lorenzo , Rodella Stefano , Zoppini Giacomo , Zenari Luciano , Falezza Giancarlo
Published: February 2006

Objectives  To assess associations between the activity of hypothalamo‐pituitary‐adrenal (HPA) axis and liver histology in patients with nonalcoholic fatty liver disease (NAFLD).

Design and patients  In a cross‐sectional study, we enrolled 50 consecutive, overweight, NAFLD patients and 40 control subjects who were comparable for age, sex and body mass index (BMI).

Measurements  NAFLD (by liver biopsy), HPA axis activity (by 24‐hour urinary free cortisol [UFC] excretion and serum cortisol levels after 1 mg dexamethasone), insulin resistance (by homeostasis model assessment: HOMA‐IR), and metabolic syndrome (MetS) features.

Results  NAFLD patients had markedly higher (P < 0·001) 24‐h UFC (149 ± 24 vs. 90 ± 16 nmol/day) and postdex suppression cortisol concentrations (32 ± 10 vs. 16 ± 7 nmol/l) than controls. The MetS and its individual components were more frequent among NAFLD patients. The marked differences in urinary/serum cortisol concentrations that were observed between the groups were little affected by adjustment for age, sex, BMI, waist circumference, systolic blood pressure, triglycerides, homeostasis model assessment for insulin resistance score and presence of diabetes. Importantly, 24‐h UFC and postdex cortisol concentrations strongly correlated to hepatic necroinflammatory grade (P < 0·01) and fibrosis stage (P < 0·001) among NAFLD patients. By logistic regression analysis, 24‐h UFC (odds ratio (OR) 1·80, 95%CI 1·3–2·8) or postdex cortisol concentrations (OR 1·95, 95%CI 1·4–3·1) independently predicted the severity of hepatic fibrosis, but not necroinflammation, after adjustment for potential confounders.

Conclusions  These results suggest that NAFLD patients have a subtle, chronic overactivity in the HPA axis (that is closely associated with the severity of liver histopathology) leading to subclinical hypercortisolism that might be implicated in the development of NAFLD.
Sorption of phosphorus in field‐moist and air‐dried samples from four weakly developed cultivated soil profiles
Authors: Peltovuori T.
Published: February 2006

Sorption of phosphorus (P) in complete soil profiles in northern Europe is not adequately documented. I measured the sorption in genetic horizons of four cultivated soils (Inceptisols, Spodosol) in Finland using both field‐moist and air‐dried soil samples, fitted modified Freundlich equations (Q = a × Ib − q) to the data, and presented the results in quantity/intensity (Q/I) graphs. Least‐squares‐estimates for the parameters of the modified Freundlich equation (a, b, q) were found to be imprecise measures of sorption. Values derived from the fitted equations (the amount of P sorbed at the P concentration of 2 mg litre−1 and P buffering capacity at the same concentration) were more precise. Both were correlated with concentrations of oxalate‐extractable iron and aluminium. In all soils, there was a distinct difference in sorption between the fertilized Ap horizons and the subsurface horizons, which retained P strongly. Most of the sorption capacity was located in the B horizons at depths between 0.3 and 0.7 m. The results demonstrate the effects of soil‐forming processes and human impact on the sorption of P in the soils. Drying the samples prior to the sorption experiments altered the shape of the Q/I graphs. It increased dissolution of P at small P concentrations, sorption at large P concentrations, and the estimates for P buffering capacity. The effects of drying soil samples on the results and the imprecision of the parameters estimated with the modified Freundlich equation should be taken into account when interpreting results of Q/I experiments.
Nurses' role in informing breast cancer patients: a comparison between patients' and nurses' opinions
Authors: Suominen Tarja , Leino‐Kilpi Helena , Laippda Pekka
Published: February 2006

The present study was conducted to determine which nursing care activities in informing breast cancer patients are considered important by the patients themselves and their nurses. One hundred and nine breast‐operated women and 125 nurses participated in the study. All patients had contracted breast cancer in the previous 3 years but not within the previous 3 months. Ward and clinical nurses from one university and six area hospitals were contacted. The patients considered that the information that they had received and their level of knowledge of their own situation was not conducive to good recovery. The nurses' opinions were in agreement, although their overall assessment of the situation was more positive.
An argument against the use of the concept of ‘persons’ in health care ethics
Authors: Allmark Peter
Published: February 2006

This paper discusses the use of the concept of ‘persons’, and its related principle ‘respect for persons’, in health care ethics. It is suggested that the main use of the concept is in attempts to answer the questions: Who owes moral respect? and ‘To whom is it owed?’. An examination of different writers and their use of the concept of ‘persons’ show it to be unsuccessful in answering the first question, and dangerous and unacceptable in answering the second. Therefore, it is suggested the concept should not be used at all in health care ethics. An alternative idea is suggested, based on the work of Hursthouse (1992).
Dehydration: burden or benefit to the dying patient?
Authors: Sutcliffe Jayne , Holmes Susan
Published: February 2006

Significant numbers of patients die each year from malignant disease. The question of whether or not to administer artificial hydration therapy to the patient who is in the last few days of life has been discussed for some time. Some health care professionals contend that a reduced fluid intake, which often accompanies the dying process, may result in a potentially painful and distressing state of dehydration, requiring preventative measures of fluid replacement therapy. In contrast, other clinicians suggest that artificial hydration is often of no proven benefit in the context of the dying and may impose additional physical and psychological burdens on the patient. This paper investigates the advantages and disadvantages of artificial hydration therapies in terms of the symptom distress experienced by the terminally ill cancer patient. Its aim is to promote discussion about this vital aspect of patient care.
Keeping it secret: the costs and benefits of nursing's hidden work in discharging patients
Authors: McWilliam Carol L. , Wong Carol A.
Published: February 2006

Workload analysts and nursing theorists alike continue their attempts to capture the hidden work of nursing, with varying degrees of success. An interpretative study of the process of discharging patients from hospital to care at home led to a new understanding of the context‐related work which nurses do. Three components of context‐related work were identified: working with the characteristics of bureaucracy; compensating for bureaucracy on behalf of the health care team; and providing leadership which ensured effective care from others. All constituted invaluable yet obscured and unrecognized components of nursing's indirect contribution to patient care. The costs to keeping this work ‘secret’ were readily apparent. The understanding derived from this research affords new insights into why nursing has kept this hidden work secret. These insights, in turn, help identify potential solutions for consideration by all concerned about nursing's professional role, status and identity.
Violence in psychiatric hospitals: are certain staff prone to being assaulted?
Authors: Whittington Richard , Wykes Til
Published: February 2006

The study reported here investigates (a) whether certain staff in psychiatric hospitals are more prone to being assaulted; (b) whether such proneness can be defined in terms of fixed attributes of these individuals (e.g. sex, personality); and (c) whether staff and patients with certain attributes are regularly combined in violent incidents. The characteristics of 65 nurses and 22 patients involved in 100 consecutive violent incidents were examined. A quarter of hospital staff were assaulted over 3 months but few were assaulted repeatedly. Those who were assaulted more than once were usually assaulted by the same patient, indicating problematic relationships rather than problematic individuals. Only two variables (age and grade) varied significantly between the assaulted and control group staff. It is argued that future research should focus on staff and patient behaviour in violent incidents rather than the characteristics of each.
The influence of positivistic thought on nineteenth century asylum nursing
Authors: Cheung Chung Man , Nolan Peter
Published: February 2006

The development of positivism, which had a considerable influence on the evolution of psychiatric thought and practice during the second half of the nineteenth century, is outlined. It was within this intellectual framework that figures such as Kraepelin, Bleuler and Schneider developed psychiatric nosologies and diagnostic criteria for certain mental illnesses. While there was little scientific evidence to support the claim that medical treatments had any beneficial effects on psychiatric disorders, nevertheless psychiatric institutions were established in the mid‐nineteenth century based on the medical model. Nurses were expected to observe, collect and report data on mental patients which were then presented to doctors for analysis. The intellectual climate of the asylums was such that nurses were not encouraged to question the scientific principles upon which the therapeutic regime was based, nor were they encouraged to seek a rationale for their daily observations and data collection. The specialized training for asylum nurses which was introduced towards the end of the nineteenth century did not give nurses their own professional identity, but rather reinforced the supremacy of medical knowledge in the care of the mentally ill. Trained nurses enhanced medical credibility, but did not progress care of the mentally ill because their training did not imply or encourage questioning of the positivistic basis of psychiatric treatment.
Development of the long‐term medication behaviour self‐efficacy scale: qualitative study for item development
Authors: De Geest Sabina , Abraham Ivo , Gemoets Hilde , Evers Georges
Published: February 2006

There are no published instruments of patient self‐efficacy related to medication behaviour, yet understanding and promoting medication compliance are central to nursing practice. The purpose of this qualitative study was to explore patient perceptions, experiences and practices associated with long‐term medication behaviour in order to establish an instrument measuring self‐efficacy in medication behaviour. In‐depth interviews were conducted with 14 patients with lifelong dependency on medicine. Using a phenomenological method of analysis the following themes emerged, all of which could be integrated within Bandura's conceptualization of dimensions of self‐efficacy. The dimension of personal attributes comprised the themes of emotional distress, confidence in the physician, perceived health status, and normalcy. Environmental factors included the themes of routine, distraction, social support and cost of medication. The third dimension of self‐efficacy, task‐related and behavioural factors was composed of the themes of side‐effects, drug delivery system, medication aids, medication schedule, and knowledge. Based on these themes, items for the Long‐Term Medication Behaviour Self‐Efficacy Scale, were developed and integrated into a version that is currently being submitted to further psychometric work.
Getting dressed in the early morning: styles of staff/patient interaction on rehabilitation hospital wards for elderly people
Authors: Waters Karen R.
Published: February 2006

This paper presents findings from a study of the nursing role in rehabilitation hospital wards for elderly people and focuses on early morning dressing; this is a microcosm of service delivery but it illustrates the way in which institutional practices impinge on patient experiences and highlights areas which warrant attention for the future development of rehabilitation services for elderly people in hospital. The reported findings are drawn from a non‐participant structured observational study of ‘early morning rising’ on rehabilitation wards for elderly people.