bluuebunny/crossref_metadata_2025 huggingface dataset:
A table of elliptic integrals: cubic cases
Authors: Carlson B. C.
Published: June 2010

Forty-one integrands that are rational except for the square root of a cubic polynomial with known real zeros are integrated in terms of R-functions for which Fortran codes are available. In contrast to conventional tables the interval of integration is not required to begin or end at a singular point of the integrand. The table contains one elliptic integral of the first kind, 26 of the second kind, and 14 of the third kind. Only 10 of the integrals are treated in standard tables, which list a large number of special cases that are unified here.
A new method for producing large Carmichael numbers
Authors: Dubner H.
Published: June 2010

A new method for producing large three-component Carmichael numbers is derived. Only two primes must be found simultaneously instead of three as in the "standard" method. For each set of two primes many third primes can be found. Several Carmichael numbers with more than 3000 digits are shown, with the largest having 3710 digits.
Numerical solution of some classical differential-difference equations
Authors: Marsaglia George , Zaman Arif , Marsaglia John C. W.
Published: June 2010

For differential-difference equations, we provide a method that gives numerical solutions accurate to hundreds or even thousands of digits. We illustrate with numerical solutions to three classical problems. With a few exceptions, previous claims of extended accuracy for these problems are found to be wrong.
The construction of preconditioners for elliptic problems by substructuring. IV
Authors: Bramble James H. , Pasciak Joseph E. , Schatz Alfred H.
Published: June 2010

We consider the problem of solving the algebraic system of equations which result from the discretization of elliptic boundary value problems defined on three-dimensional Euclidean space. We develop preconditioners for such systems based on substructuring (also known as domain decomposition). The resulting algorithms are well suited to emerging parallel computing architectures. We describe two techniques for developing these preconditioners. A theory for the analysis of the condition number for the resulting preconditioned system is given and the results of supporting numerical experiments are presented.
Weight functions for Chebyshev quadrature
Authors: Xu Yuan
Published: June 2010

In this paper, we investigate if the weight function

(
1
−

x
2

)

−
1

/

2

R
(
x
)

{(1 - {x^2})^{ - 1/2}}R(x)

, where

R
(
x
)

R(x)

is a rational function of order (1,1), admits Chebyshev quadratures. Many positive examples are provided. In particular, we have proved that the answer is affirmative if

R
(
x
)
=
1
+
b
x

R(x) = 1 + bx

,

|

b

|

>
0.27846
…

|b| > 0.27846 \ldots

.
Numerical approximation of minimum norm solutions of 𝐾𝑓=𝑔 for special 𝐾
Authors: Luecke Glenn R.
Published: June 2010

Let

K
:

L
2

(
Y
,
μ
)
→

L
2

(
X
,
ν
)

K:{L_2}(Y,\mu ) \to {L_2}(X,\nu )

be continuous and linear and assume
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="left-parenthesis upper K f right-parenthesis left-parenthesis x right-parenthesis equals integral Subscript upper Y Superscript Baseline k left-parenthesis x comma y right-parenthesis f left-parenthesis y right-parenthesis d mu left-parenthesis y right-parenthesis">

(
K
f
)
(
x
)
=

∫
Y

k
(
x
,
y
)
f
(
y
)

d
μ
(
y
)

(Kf)(x) = \smallint _Y^{} {k(x,y)f(y)\,d\mu (y)}

. Define

k
x

{k_x}

by

k
x

(
y
)
=
k
(
x
,
y
)

{k_x}(y) = k(x,y)

. Assume K has the property that (a)

k
x

∈

L
2

(
Y
,
μ
)

{k_x} \in {L_2}(Y,\mu )

for all

x
∈
X

x \in X

and (b) if

K
f
=
0

ν

Kf = 0\;\nu

-a.e., then

(
K
f
)
(
x
)
=
0

(Kf)(x) = 0

for all

x
∈
X

x \in X

. For example, if

X
=
Y
=
[
0
,
1
]

X = Y = [0,1]

,

μ
=
ν

\mu = \nu

is Lebesgue measure and if

k
(
x
,
y
)

k(x,y)

satisfies a Lipschitz condition in x, then K has the above property. Assume K satisfies this property and

f
0

{f_0}

is a minimum

L
2

{L_2}

norm solution of the first-kind integral equation

(
K
f
)
(
x
)
=
g
(
x
)

(Kf)(x) = g(x)

for all

x
∈
X

x \in X

. It is shown that

f
0

{f_0}

is the

L
2

{L_2}

-norm limit of linear combinations of the

k

x
i

{k_{{x_i}}}

’s. It is then shown how to choose constants

c
1

,
…
,

c
n

{c_1}, \ldots ,{c_n}

to minimize

‖

f
0

−

∑

j
=
1

n

c
j

k

x
j

‖

\left \| {{f_0} - \sum \nolimits _{j = 1}^n {{c_j}{k_{{x_j}}}} } \right \|

without knowing what

f
0

{f_0}

is. This paper also contains results on how to choose the

k

x
j

{k_{{x_j}}}

’s as well as numerical examples illustrating the theory.
The validity of Shapiro’s cyclic inequality
Authors: Troesch B. A.
Published: June 2010

A cyclic sum

S
N

(

x

)
=
∑

x
i

/

(

x

i
+
1

+

x

i
+
2

)

{S_N}({\mathbf {x}}) = \sum {{x_i}/({x_{i + 1}} + {x_{i + 2}})}

is formed with N components of a vector x, where in the sum

x

N
+
1

=

x
1

{x_{N + 1}} = {x_1}

,

x

N
+
2

=

x
2

{x_{N + 2}} = {x_2}

, and where all denominators are positive and all numerators are nonnegative. It is known that there exist vectors x for which

S
N

(

x

)
>
N

/

2

{S_N}({\mathbf {x}}) > N/2

if

N
≥
14

N \geq 14

and even, and if

N
≥
24

N \geq 24

. It has been proved that the inequality

S
N

(

x

)
≥
N

/

2

{S_N}({\mathbf {x}}) \geq N/2

holds for

N
≤
13

N \leq 13

. Although it has been conjectured repeatedly that the inequality also holds for odd N between 15 and 23, this has apparently never been proved. Here we will confirm that the inequality indeed holds for all odd

N
≤
23

N \leq 23

. This settles the question for all N.
On the stability of relaxed incomplete 𝐿𝑈 factorizations
Authors: Bruaset A. M. , Tveito A. , Winther R.
Published: June 2010

When solving large linear systems of equations arising from the discretization of elliptic boundary value problems, a combination of iterative methods and preconditioners based on incomplete LU factorizations is frequently used. Given a model problem with variable coefficients, we investigate a class of incomplete LU factorizations depending on a relaxation parameter. We show that the associated preconditioner and the factorization itself both are numerically stable. The theoretical results are complemented by numerical experiments.
Rigorous sensitivity analysis for systems of linear and nonlinear equations
Authors: Rump Siegfried M.
Published: June 2010

Methods are presented for performing a rigorous sensitivity analysis of numerical problems with independent, noncorrelated data for general systems of linear and nonlinear equations. The methods may serve for the following two purposes. First, to bound the dependency of the solution on changes in the input data. In contrast to condition numbers, a componentwise sensitivity analysis of the solution vector is performed. Second, to estimate the true solution set for problems whose input data are subject to tolerances. The methods presented are very effective and have the additional property that, owing to an automatic error control mechanism, every computed result is guaranteed to be correct. Examples are given for linear systems, demonstrating that the computed bounds are in general very sharp. Interesting comparisons to traditional condition numbers are given.
The integral of the 𝑛th power of the Voigt function
Authors: Reichel Alex
Published: June 2010

A series expansion is given for the computation of the integral over

(
−
∞
,
∞
)

( - \infty ,\infty )

of the

n
n

th power of the Voigt function for use in spectral line calculations with Doppler broadening. A nine significant figure table is presented for

n
n

up to 25 and for a wide range of values of the second parameter on a microfiche card in this issue.
Simplified forecasting by polynomial regression with equally spaced values of the independent variable
Authors: Laderman Jack , Laderman Julian D.
Published: June 2010

A method is developed and tables are presented which yield polynomial least squares forecasts by computing the inner product of two n-component vectors, where n is the number of observed points.
Time discretization in the backward solution of parabolic equations. II
Authors: Eldén Lars
Published: June 2010

The backward beam method for solving a parabolic partial differential equation backward in time is studied. Time discretizations based on Padé approximations of the exponential function are considered, and a priori estimates of the step length are given, which guarantee an almost optimal error bound. The computational efficiency of different discretizations is discussed. Some numerical examples are given, which compare the backward beam method and the regularization method studied in Part I of this paper.
Quantitative Analysis of the Mechanism of Endocytic Actin Patch Assembly and Disassembly in Fission Yeast
Authors: Sirotkin Vladimir , Berro Julien , Macmillan Keely , Zhao Lindsey , Pollard Thomas D.
Published: June 2010

We used quantitative confocal microscopy to measure the numbers of 16 proteins tagged with fluorescent proteins during assembly and disassembly of endocytic actin patches in fission yeast. The peak numbers of each molecule that accumulate in patches varied <30–50% between individual patches. The pathway begins with accumulation of 30–40 clathrin molecules, sufficient to build a hemisphere at the tip of a plasma membrane invagination. Thereafter precisely timed waves of proteins reach characteristic peak numbers: endocytic adaptor proteins (∼120 End4p and ∼230 Pan1p), activators of Arp2/3 complex (∼200 Wsp1p and ∼340 Myo1p) and ∼300 Arp2/3 complexes just ahead of a burst of actin assembly into short, capped and highly cross-linked filaments (∼7000 actins, ∼200 capping proteins, and ∼900 fimbrins). Coronin arrives last as all other components disperse upon patch internalization and movement over ∼10 s. Patch internalization occurs without recruitment of dynamins. Mathematical modeling, described in the accompanying paper (Berro et al., 2010, MBoC 21: 2905–2915), shows that the dendritic nucleation hypothesis can account for the time course of actin assembly into a branched network of several hundred filaments 100–200 nm long and that patch disassembly requires actin filament fragmentation in addition to depolymerization from the ends.
Long‐term proliferation and characterization of human spermatogonial stem cells obtained from obstructive and non‐obstructive azoospermia under exogenous feeder‐free culture conditions
Authors: Lim J. J. , Sung S.‐Y. , Kim H. J. , Song S.‐H. , Hong J. Y. , Yoon T. K. , Kim J. K. , Kim K.‐S. , Lee D. R.
Published: June 2010

Objectives:  The aim of the present study was to improve efficiency of isolation and to optimize proliferative potential of human spermatogonial stem cells (SSCs) obtained from obstructive azoospermic (OA) and non‐obstructive azoospermic (NOA) patients, and further, to characterize these cells for potential use in infertility treatment or study of reproductive biology.

Materials and methods:  We have applied a cell‐sorting method, using collagen and magnetic activated cell separation to overcome obstacles, developing a collection system, and simple long‐term proliferation system, that yields large numbers of high‐purity SSCs from obstructive OA and NOA patients.

Results:  SSCs derived from OA and NOA patients proliferated and maintained their characteristics for more than 12 passages (>6 months) in vitro. Moreover, the population of cells positive for the SSC‐specific markers GFRα‐1 and integrin α6, increased to more than 80% at passage 8.

Conclusion:  These finding may support the idea that in vitro propagation of SSCs could be a useful tool for infertility treatment and study of reproductive biology.
Proper Gcn5 histone acetyltransferase expression is required for normal anteroposterior patterning of the mouse skeleton
Authors: Lin Wenchu , Zhang Zhijing , Chen Chih‐Hsin , Behringer Richard R. , Dent Sharon Y. R.
Published: June 2010

Histone acetylation plays important roles in gene regulation. However, the functions of individual histone acetyltransferases (HATs) in specific developmental transcription programs are not well defined. To define the functions of Gcn5, a prototypical HAT, during mouse development, we have created a series of mutant Gcn5 alleles. Our previous work revealed that deletion of Gcn5 leads to embryonic death soon after gastrulation. Embryos homozygous for point mutations in the catalytic center of Gcn5 survive longer, but die soon after E16.0 and exhibit defects in cranial neural tube closure. Embryos bearing a hypomorphic Gcn5flox(neo) allele also exhibit neural closure defects and die at or soon after birth. We report here that Gcn5flox(neo)/flox(neo) and Gcn5flox(neo)/Δ embryos exhibit anterior homeotic transformations in lower thoracic and lumbar vertebrae. These defects are accompanied by a shift in the anterior expression boundary of Hoxc8 and Hoxc9. These data provide the first evidence that Gcn5 contributes to Hox gene regulation and is required for normal anteroposterior patterning of the mouse skeleton.
Role of CCN, a vertebrate specific gene family, in development
Authors: Katsube Ken‐ichi , Sakamoto Kei , Tamamura Yoshihiro , Yamaguchi Akira
Published: June 2010

The CCN family of genes constitutes six members of small secreted cysteine rich proteins, which exists only in vertebrates. The major members of CCN are CCN1 (Cyr61), CCN2 (CTGF), and CCN3 (Nov). CCN4, CCN5, and CCN6 were formerly reported to be in the Wisp family, but they are now integrated into CCN due to the resemblance of their four principal modules: insulin like growth factor binding protein, von Willebrand factor type C, thrombospondin type 1, and carboxy‐terminal domain. CCNs show a wide and highly variable expression pattern in adult and in embryonic tissues, but most studies have focused on their principal role in osteo/chondrogenesis and vasculo/angiogenesis from the aspect of migration, growth, and differentiation of mesenchymal cells. CCN proteins simultaneously integrate and modulate the signals of integrins, bone morphogenetic protein, vascular endothelial growth factor, Wnt, and Notch by direct binding. However, the priority in the use of the signals is different depending on the cell status. Even the equivalent counterparts show a difference in signal usage among species. It may be that the evolution of the CCN family continues to keep pace with vertebrate evolution itself.
Demographic characteristics, patterns and risk factors for retinal vein occlusion in Nepal: a hospital‐based case–control study
Authors: Thapa Raba , Paudyal Govinda , Bernstein Paul S
Published: June 2010

Abstract

Purpose:  Retinal vein occlusion (RVO) is an increasing problem leading to visual impairment in Nepal. Our study investigates the demographic characteristics, patterns and risk factors for RVO in this developing Asian country.

Methods:  This is a hospital‐based case–control study conducted at the Tilganga Institute of Ophthalmology of Nepal during the period of January 2007 to January 2008. All consecutive new cases of RVO diagnosed at the Institute were included. Cases with intraocular inflammation or a prior history of intraocular injections, laser therapy or vitrectomy for RVO were excluded from the study. Age, sex and geographically matched subjects were recruited as a control group from patients who presented for regular eye examinations at the same hospital during the study period.

Results:  A total of 218 patients with RVO presented during the study period. The mean age of the patients was 61.1 ± 12.3 years with more men (58.3%) than women. The mean age for control groups was 61.3 ± 13.0 years. Seventy per cent of subjects had branch retinal vein occlusion, whereas central retinal vein occlusion was present in 26.6%. 63.9% of branch retinal vein occlusion was found in the superotemporal branch. Hypermetropia, primary open angle glaucoma, hypertension, mixed diabetes and hypertension, and heart disease were significantly higher in RVO cases as compared with the control group.

Conclusion:  The demographic characteristics, patterns and risk factors of RVO in Nepal can help guide interventions against these blinding diseases in similar developing countries.
Interventions for apnoea of prematurity: a personal view
Authors: Poets CF
Published: June 2010

Aim:  To review treatments for apnoea of prematurity (AOP).

Methods:  Literature Review and description of personal practice.

Results:  Provided that symptomatic apnoea has been ruled out, interventions to improve AOP can be viewed as directed at one of three underlying mechanisms: (i) a reduced work of breathing [e.g. prone positioning, nasal continuous positive airway pressure (CPAP)], (ii) an increased respiratory drive (e.g. caffeine), and (iii) an improved diaphragmatic function (e.g. branched‐chain amino acids). Most options currently applied, however, have not yet been shown to be effective and/or safe, except for prone, head‐elevated positioning, synchronized nasal ventilation/CPAP, and caffeine.

Conclusion:  Treatment usually follows an incremental approach, starting with positioning, followed by caffeine (which should be started early, at least in infants <1250 g), and nasal ventilation or CPAP via variable flow systems that reduce work of breathing. From a research point of view, we most urgently need data on the frequency and severity of bradycardia and intermittent hypoxia that can yet be tolerated without putting an infant at risk of impaired development or retinopathy of prematurity.
The case of ‘losses in any event’: a question of duty, cause or damages?
Authors: Stiggelbout Mark
Published: June 2010

This paper considers the relevance of a finding that, even absent the defendant's unlawfulness, the private law claimant would have suffered the losses claimed. It provides a principled framework for considering the issues raised by such a finding of ‘losses in any event’, arguing that it should be distinguished both from causation of injury and from the scope of the defendant's duty of care, and that it should be treated as raising a question of damages. It highlights the need, particularly in pure economic loss cases, for a careful comparison of the real and the hypothetical losses so as to determine whether the latter would indeed have been losses in any event. In this regard, the decision of the Court of Appeal inCalvert v William Hill Credit Ltdis subjected to close scrutiny. A more general argument advanced is that tort and contract both do and should adopt similar approaches in this field.
Validation of the Cat as a Model for the Human Lumbar Spine During Simulated High-Velocity, Low-Amplitude Spinal Manipulation
Authors: Ianuzzi Allyson , Pickar Joel G. , Khalsa Partap S.
Published: June 2010

High-velocity, low-amplitude spinal manipulation (HVLA-SM) is an efficacious treatment for low back pain, although the physiological mechanisms underlying its effects remain elusive. The lumbar facet joint capsule (FJC) is innervated with mechanically sensitive neurons and it has been theorized that the neurophysiological benefits of HVLA-SM are partially induced by stimulation of FJC neurons. Biomechanical aspects of this theory have been investigated in humans while neurophysiological aspects have been investigated using cat models. The purpose of this study was to determine the relationship between human and cat lumbar spines during HVLA-SM. Cat lumbar spine specimens were mechanically tested, using a displacement-controlled apparatus, during simulated HVLA-SM applied at L5, L6, and L7 that produced preload forces of ∼25% bodyweight for 0.5 s and peak forces that rose to 50–100% bodyweight within ∼125 ms, similar to that delivered clinically. Joint kinematics and FJC strain were measured optically. Human FJC strain and kinematics data were taken from a prior study. Regression models were established for FJC strain magnitudes as functions of factors species, manipulation site, and interactions thereof. During simulated HVLA-SM, joint kinematics in cat spines were greater in magnitude compared with humans. Similar to human spines, site-specific HVLA-SM produced regional cat FJC strains at distant motion segments. Joint motions and FJC strain magnitudes for cat spines were larger than those for human spine specimens. Regression relationships demonstrated that species, HVLA-SM site, and interactions thereof were significantly and moderately well correlated for HVLA-SM that generated tensile strain in the FJC. The relationships established in the current study can be used in future neurophysiological studies conducted in cats to extrapolate how human FJC afferents might respond to HVLA-SM. The data from the current study warrant further investigation into the clinical relevance of site targeted HVLA-SM.
Axons Pull on the Brain, But Tension Does Not Drive Cortical Folding
Authors: Xu Gang , Knutsen Andrew K. , Dikranian Krikor , Kroenke Christopher D. , Bayly Philip V. , Taber Larry A.
Published: June 2010

During human brain development, the cerebral cortex undergoes substantial folding, leading to its characteristic highly convoluted form. Folding is necessary to accommodate the expansion of the cerebral cortex; abnormal cortical folding is linked to various neurological disorders, including schizophrenia, epilepsy, autism, and mental retardation. Although this process requires mechanical forces, the specific force-generating mechanisms that drive folding remain unclear. The two most widely accepted hypotheses are as follows: (1) Folding is caused by differential growth of the cortex and (2) folding is caused by mechanical tension generated in axons. Direct evidence supporting either theory, however, is lacking. Here we show that axons are indeed under considerable tension in the developing ferret brain, but the patterns of tissue stress are not consistent with a causal role for axonal tension. In particular, microdissection assays reveal that significant tension exists along axons aligned circumferentially in subcortical white matter tracts, as well as those aligned radially inside developing gyri (outward folds). Contrary to previous speculation, however, axonal tension is not directed across developing gyri, suggesting that axon tension does not drive folding. On the other hand, using computational (finite element) models, we show that differential cortical growth accompanied by remodeling of the subplate leads to outward folds and stress fields that are consistent with our microdissection experiments, supporting a mechanism involving differential growth. Local perturbations, such as temporal differences in the initiation of cortical growth, can ensure consistent folding patterns. This study shows that a combination of experimental and computational mechanics can be used to evaluate competing hypotheses of morphogenesis, and illuminate the biomechanics of cortical folding.
Controlled formation of condensed frost layers in cryogenic high vacuum pumps
Authors: Syssoev Sergei E. , Eacobacci Michael J. , Bartlett Allen J.
Published: June 2010

Cryopumping involves the condensation and solidification of gas onto cryogenically cooled array surfaces. Control of the formation of the frost layers within the pump can improve its performance from both a vacuum and a capacity viewpoint. Vacuum performance of a cryopump involves the consistent attainment of required pressure levels within process allotted time constraints. Cryopump capacity involves the achievement of requisite vacuum levels for extended periods of time before regeneration is required. This article summarizes developments in the understanding of frost layer formation and its influence on cryopump vacuum performance and capacity.
Chemical-etch-assisted growth of epitaxial zinc oxide
Authors: Adles E. J. , Aspnes D. E.
Published: June 2010

The authors use real-time spectroscopic polarimetric observations of growth, and a chemical model derived therefrom, to develop a method of growing dense, two-dimensional zinc oxide epitaxially on sapphire by metal organic chemical vapor deposition. Particulate zinc oxide formed in the gas phase is used to advantage as the deposition source. Their real-time data provide unequivocal evidence that a seed layer is required, unwanted fractions of ZnO are deposited, but these fractions can be removed by cycling between brief periods of net deposition and etching. The transition between deposition and etching occurs with zinc precursor concentrations that only differ by 13%. These processes are understood by considering the chemistry involved.
Electrical and optical properties of Nb-doped TiO2 films deposited by dc magnetron sputtering using slightly reduced Nb-doped TiO2−x ceramic targets
Authors: Sato Yasushi , Sanno Yuta , Tasaki Chihiro , Oka Nobuto , Kamiyama Toshihisa , Shigesato Yuzo
Published: June 2010

Nb-doped anatase TiO2 films were deposited on unheated glass by dc magnetron sputtering using slightly reduced Nb-doped TiO2−x targets (Nb concentration: 3.7 and 9.5 at. %) with various hydrogen or oxygen flow ratios. After postannealing in a vacuum (6×10−4 Pa) at 500 °C for 1 h, both films were crystallized into the polycrystalline anatase TiO2 structure. The resistivity decreased from 1.6×10−3 to 6.3×10−4 Ω cm with increasing Nb concentration from 2.8 to 8.0 at. %, where the carrier density increased from 5.4×1020 to 2.0×1021 cm−3 and the Hall mobility was almost constant at 5–7 cm2 V−1 s−1. The films exhibited a high transparency of over 60%–80% in the visible region.
Deposited nanorod films for photonic crystal biosensor applications
Authors: Zhang Wei , Kim Seok-min , Ganesh Nikhil , Block Ian D. , Mathias Patrick C. , Wu Hsin-Yu , Cunningham Brian T.
Published: June 2010

Planar photonic crystals have been used as the basis of many biological sensing devices. Here, the authors successfully demonstrated that the combination of the photonic crystal structures and a dielectric nanorod coating prepared by the glancing-angle deposition technique can lead to significant increases in the device sensitivity. By incorporating a TiO2 nanorod coating onto the label-free photonic crystal biosensor structure, the surface area of the device is increased. The results for detection of polymer films and proteins indicate up to a 5.5 fold enhancement of detected adsorbed mass density.
Offering Individual Genetic Research Results: Context Matters
Authors: Beskow Laura M. , Burke Wylie
Published: June 2010

Beyond a fundamental duty to rescue, a one-size-fits-all threshold cannot be developed for decisions about the return of individual results.
Seroepidemiology of Helicobacter pylori infection and hepatitis A in a rural area: evidence against a common mode of transmission
Authors: Luzza F , Imeneo M , Maletta M , Paluccio G , Giancotti A , Perticone F , Focà A , Pallone F
Published: June 2010

Background and aims—Recent studies have shown that the age-specific seroprevalence of H pylori infection parallels hepatitis A (HAV), suggesting similar modes of transmission. The aim of this study was to investigate the seroepidemiology ofH pylori and HAV in the same setting.

Patients—A sample of 705 resident subjects (273 men, age range 1–87 years, median 50) who attended the outpatient medical centre of the rural town of Cirò, Southern Italy (11 000 inhabitants) for blood testing were recruited.

Methods—All subjects completed a structured questionnaire. A serum sample was drawn from each subject and assayed for H pylori IgG by a validated in house enzyme linked immunosorbent assay. Antibodies to HAV were determined in 466 subjects (163 men, age range 1–87 years, median 49). A measure of agreement between H pylori and HAV seropositivity, the κ statistic, was used.

Results—Overall, 446 (63%) subjects were seropositive for H pylori. Of the 466 subjects screened for both H pylori and HAV, 291 (62%) were seropositive for H pylori and 407 (87%) for HAV. Cross-tabulation of these data showed that 275 (59%) were seropositive and 43 (9%) seronegative for both H pylori and HAV, 16 (3%) were seropositive for H pylori, and 132 (28%) were seropositive for HAV (OR = 5.6, CI 3 to 10). There was a parallel, weakly correlated (r = 0.287) rise in the seroprevalence of the two infections with increasing age. However, the agreement between H pylori and HAV seropositivity was little better than chance (κ = 0.21) and in those aged less than 20 years it was worse than chance (κ = –0.064). Furthermore, multiple logistic regression analysis did not show any risk factor shared by both infections.

Conclusions—The correlation between H pylori and HAV reflects the age-specific seroprevalence of both infections rather than a true association. This study provides evidence against a common mode of transmission of H pylori and HAV.
Energy expenditure and body composition in children with Crohn’s disease: effect of enteral nutrition and treatment with prednisolone
Authors: Azcue M , Rashid M , Griffiths A , Pencharz P B
Published: June 2010

Background—Malnutrition and growth retardation are common complications of Crohn’s disease in children. The contribution of resting energy expenditure (REE) to malnutrition is unclear.

Aims—To characterise the REE and body composition in children with Crohn’s disease and compare them with normal controls and patients with anorexia nervosa; to compare the effects of prednisolone and enteral nutrition on energy expenditure and body composition.

Subjects—Twenty four children with Crohn’s disease, 19 malnourished females with anorexia nervosa, and 22 healthy control subjects were studied.

Methods—In children with Crohn’s disease measurements were done when the disease was acute and repeated at one and three months after treatment with either prednisolone or enteral nutrition. Resting energy expenditure was measured by indirect calorimetry and body composition by anthropometry, bioelectrical impedance analysis, total body potassium, H218O, and bromide space studies.

Results—Body weight and ideal body weight were significantly lower in patients with Crohn’s disease than in healthy controls. Lean tissue was depleted and there was an increase in extracellular water. Per unit of lean body mass, there was no difference between REE in patients with Crohn’s disease and controls, whereas patients with anorexia nervosa had significantly reduced REE. With enteral nutrition all body compartments and REE increased significantly (p<0.001). In a subgroup of age-matched men there was a significant increase in height after three months of enteral nutrition compared with prednisolone (p<0.01). Those treated with steroids did not show a significant change in height but did show an increase in all body compartments. However, intracellular water as well as lean body mass accretion were significantly higher in the enteral nutrition group than in the prednisolone group.

Conclusions—Despite being malnourished, children with Crohn’s disease fail to adapt their REE per unit of lean body mass. This might be a factor contributing to their malnutrition. Lean tissue accretion is higher in patients treated with enteral nutrition than in those treated with prednisolone.
Contribution of acid and duodenogastrooesophageal reflux to oesophageal mucosal injury and symptoms in partial gastrectomy patients
Authors: Vaezi M F , Richter J E
Published: June 2010

Background—The role of acid and pepsin in causing symptoms and oesophagitis is well established; however, the significance of duodenogastro-oesophageal reflux (DGOR) in this disorder is unclear.

Aims—To understand the role of acid and DGOR in causing upper gastrointestinal (GI) symptoms and oesophageal mucosal injury in partial gastrectomy (PG) patients.

Methods—Thirty two PG patients with upper GI symptoms were studied. Twenty four hour ambulatory acid and bilirubin measurements were obtained with Bilitec 2000 using glass electrode and fibreoptic sensor. Upper GI symptoms and oesophagitis were correlated with either acid or DGOR.

Results—The PG patients were a heterogeneous group: 28% (9/32) had mixed reflux (acid+/DGOR+); 50% (16/32) had only DGOR (acid−/DGOR+); and 22% (7/32) had neither (acid−/DGOR−). Upper GI symptoms were associated with both mixed reflux (69%) and DGOR (24%). Six patients (67%) in the acid+/DGOR+ group had oesophagitis; no acid−/DGOR+ or acid−/DGOR− patients had oesophagitis. Mixed reflux showed a significant (p<0.0001) association with oesophagitis, while DGOR did not (p=0.3).

Conclusions—(1) The majority of upper GI symptoms and all cases of oesophagitis in the PG patients occurred in patients who had mixed refluxate (acid and DGOR); (2) DGOR without simultaneous acid reflux may cause symptoms, but was not associated with oesophagitis in this patient group.
Red kidney bean lectin is a potent cholecystokinin releasing stimulus in the rat inducing pancreatic growth
Authors: Herzig K-H , Bardocz S , Grant G , Nustede R , Fölsch U R , Pusztai A
Published: June 2010

Background—Lectins are proteins capable of specific binding to carbohydrates without altering their covalent structure. As an essential part of plants they are ingested in our daily diet. By binding to glycosyl side chains of receptors lectins can mimic or inhibit the action of the ligand. Oral administration of phytohaemagglutinin (PHA) in rats dose dependently induces growth of the small intestine and the pancreas by an unknown mechanism.

Aims—To investigate the mechanism of PHA induced intestinal and pancreatic growth.

Methods—Thirty day old male rats were pairfed for 10 days with lactalbumin as a control diet or lactalbumin plus PHA or purified soybean trypsin inhibitor (STI) as a positive control (42 mg/rat/day) with or without 20 μg of the cholecystokinin A (CCK-A) antagonist MK 329. To investigate further the effect of PHA on CCK release intestinal mucosal cells were isolated from rats which were continuously perfused in a perfusion apparatus. CCK release into the medium was assayed.

Results—PHA and STI significantly stimulated growth of the pancreas and the small intestine. MK 329 blocked this growth effect in the pancreas but not in the small intestine. In vivo, PHA significantly increased CCK plasma levels from 0.75 to 6.67 (SEM 2.23) compared with 2.3 (0.35) pM in the control group. In addition, in vitro PHA dose dependently stimulated CCK release with a maximal effect at 100 ng/ml.

Conclusion—In vivo and in vitro PHA is a potent stimulus for CCK release in the rat, thereby inducing pancreatic growth, whereas intestinal growth is stimulated by a CCK independent mechanism.
Induction of various cytokines and development of severe mucosal inflammation by cagA gene positive Helicobacter pylori strains
Authors: Yamaoka Y , Kita M , Kodama T , Sawai N , Kashima K , Imanishi J
Published: June 2010

Background—Helicobacter pyloristrains possessing the cagA gene are thought to induce interleukin 8 (IL-8) in gastric mucosa. However, it is still unclear whether a relation exists between the cagA gene and the expression patterns of cytokines other than IL-8.

Aims—To investigate the relation between the cagA gene and the production of various cytokine proteins using an enzyme linked immunosorbent assay (ELISA).

Patients and methods—In 184 patients, the cagA gene was detected by polymerase chain reaction (PCR), and levels of production of IL-1β, IL-6, IL-7, IL-8, IL-10, and tumour necrosis factor α (TNF-α) in antral biopsy specimens were measured by ELISA.

Results—Mucosal levels of IL-1β, IL-6, IL-8, and TNF-α were significantly higher in H pyloripositive than in H pylori negative patients. Furthermore, the mucosal levels of IL-1β and IL-8 were significantly higher in specimens infected with cagApositive strains than in those infected with cagAnegative strains. In H pylori positive patients, the mucosal level of IL-8 was closely correlated with that of IL-1β (p<0.0001), and the mucosal level of IL-6 was closely correlated with that of TNF-α (p<0.0001).

Conclusion—These findings suggest that the ability to induce cytokines differs among the strains;cagA+ strains induce various kinds of cytokines and may cause severe inflammation, whereascagA− strains induce IL-8 and IL-1β only weakly and may cause only mild inflammation. However, as most patients infected with the cagA+ strains have gastritis, these strains may not be equivalent to ulcerogenic strains.
Incidence of Crohn’s disease in Stockholm County 1955–1989
Authors: Lapidus A , Bernell O , Hellers G , Persson P-G , Löfberg R
Published: June 2010

Aim—To evaluate the incidence of Crohn’s disease in Stockholm County between 1955 and 1989.

Methods—A cohort of 1936 patients with Crohn’s disease was retrospectively assembled. Incidence rates and changes in disease distribution were assessed.

Results—The mean increase in incidence was 15% (95% confidence intervals 12% to 18%) per five year period with a mean annual incidence rate at 4.6/105during the last two decades. The mean incidence for the entire study period was similar for men and women. The mean age at diagnosis increased from 25 years in 1960–64 to 32 years in 1985–89, partly because of an increasing proportion of patients aged at least 60 years at diagnosis. The proportion of patients with colonic Crohn’s disease at the time of diagnosis increased from 15% to 32% (17% difference; 95% confidence intervals 12% to 23%) whereas the proportion of patients with ileocaecal disease decreased from 58% to 41% (17% difference; 95% confidence intervals 10% to 24%) during the study period. Elderly patients had a higher proportion of small bowel disease and a lower proportion of ileocolonic disease compared with the younger patients.

Conclusion—The incidence rate of Crohn’s disease in Stockholm has stabilised at 4.6/105 and the proportion of elderly patients has increased during a 35 year period. Colonic Crohn’s disease has increased in frequency with a reciprocal decrease in ileocaecal disease.
Stimulus and site specific induction of hiccups in the oesophagus of normal subjects
Authors: Fass R , Higa L , Kodner A , Mayer E A
Published: June 2010

Background—Hiccups that are induced by a large meal have been suggested to result from gastric overdistension. The role of the oesophagus in precipitating hiccups has never been defined.

Aims—To determine the involvement of oesophageal mechanoreceptors in the hiccup reflex.

Methods—Ten normal healthy subjects were prospectively evaluated at a university affiliated hospital. Controlled inflation of a polyethylene bag in the proximal and distal oesophagus was carried out using slow ramp and rapid phasic distensions, by an electronic distension device.

Results—Hiccups were induced in four subjects only during rapid phasic distensions and only in the proximal oesophagus. The mean (SEM) minimal volume threshold for the hiccup reflex was 32.5 (4.8) ml, which was above the perception threshold. Hiccups appeared during inflation and resolved after deflation.

Conclusions—Sudden rapid stretch of the mechanoreceptors in the proximal oesophagus can trigger the hiccup reflex in normal subjects. Only rapid distensions above a determined volume threshold will predictably induce hiccups in a given subject. This mechanism may play a role in the physiological induction of hiccups.
Abnormal postprandial duodenal chyme transport in patients with long standing insulin dependent diabetes mellitus
Authors: Nguyen H N , Silny J , Wüller S , Marschall H-U , Rau G , Matern S
Published: June 2010

Abstract

Background—Patients with long standing diabetes mellitus frequently have upper gut dysmotility. Gastroparesis has been well studied, whereas detailed data on duodenal motor function are limited.

Aims—To characterise postprandial duodenal chyme transport in such patients.

Methods—Intraluminal multiple impedance measurement, recently introduced as a novel technique for investigation of chyme transport, was used to study postprandial duodenal chyme flow in 10 patients with long standing insulin dependent diabetes mellitus with gastroparesis, and 10 healthy volunteers.

Results—Four distinct transport patterns of chyme, termed bolus transport events (BTEs), were found in both groups and could be characterised as: short distance propulsive; simple long distance propulsive; retrograde; and complex long distance propulsive. Diabetic patients had significantly lower numbers of propulsive BTEs (p<0.01), and higher proportions of retrograde BTEs and complex long distance BTEs (p<0.05) than control subjects, whereas the proportion of simple long distance BTEs was significantly lower (p<0.05). The mean propagation velocities of the BTEs were similar in both groups.

Conclusion—Abnormal postprandial duodenal chyme transport was found in patients with long standing insulin dependent diabetes mellitus. This is characterised by transport disorganisation and may result in disturbed chyme clearance.
Pancreatitis induced by codeine: a case report with positive rechallenge
Authors: Hastier P , Longo F , Buckley M , Chichmanian R M , Delmont J P
Published: June 2010

A woman who developed acute pancreatitis following ingestion of low dose codeine, with positive rechallenge, is described. As this is the first case report of pancreatitis being induced solely by codeine, this side effect must be rare in view of the widespread consumption of this drug.
Studies on the gastric mucosal microcirculation. 2.Helicobacter pylori water soluble extracts induce platelet aggregation in the gastric mucosal microcirculation in vivo
Authors: Kalia N , Jacob S , Brown N J , Reed M W R , Morton D , Bardhan K D
Published: June 2010

Background—The exact mechanisms by whichHelicobacter pylori infection results in gastric mucosal injury are unclear.

Aims—To assess in vivo whether H pylori extracts could initiate an inflammatory response in the rat gastric mucosal microcirculation.

Methods—Extracts of H pylori, Escherichia coli, or distilled water were administered topically to the gastric mucosa of anaesthetised animals. Fluorescence in vivo microscopy assessed macromolecular leakage of labelled albumin from mucosal vessels, leucocyte adherence/rolling, and platelet activity for 90 minutes.

Results—H pylori induced increases (p<0.001) in adherent platelet thrombi and circulating platelet emboli after five and 15 minutes respectively. Adherent platelet thrombi (mean of four per field of view) remained significantly increased throughout the experiment, but circulating emboli (maximum of five at 30 minutes) decreased with time. Leucocyte adherence did not occur although early transient rolling was observed. An 11% increase (p<0.02) in albumin leakage occurred after five minutes only. The induction of platelet aggregation was only observed following H pyloriadministration.

Conclusion—This in vivo study demonstrated the ability of Hpylori extracts to promote platelet aggregation within gastric mucosal microvessels. Recruitment of leucocytes was not observed. The results suggest that the early events associated with H pylori infection are platelet aggregation with perhaps subsequent leucocyte recruitment by activated platelets.
Vascular anatomy defines sites of indomethacin induced jejunal ulceration along the mesenteric margin
Authors: Anthony A , Pounder R E , Dhillon A P , Wakefield A J
Published: June 2010

Background—Indomethacin induces ulceration in the rat jejunum with sparing of the ileum. The ulcers localise between vasa recta along the mesenteric margin of the bowel, observations that have not been fully explained.

Aim—To examine the relationship between the localisation of experimental ulcers and the vascular anatomy of the rat small intestine.

Methods—The normal vascular anatomy of the rat jejunum and ileum was studied and compared using arterial carbon ink perfusion. The anatomical localisation of early and advanced lesions induced by indomethacin was examined with particular reference to the vasculature. Mucosal injury induced by feeding vessel ligation for 24 hours or brief ischaemia-reperfusion injury was examined. The existence of anatomically sensitive sites to indomethacin was tested in a two dose study.

Results—In the rat jejunum, poorly vascularised sites along the mesenteric margin were highly susceptible to indomethacin induced injury, such sites being absent from the ileum. Villous contraction was a feature of both early indomethacin injury and ischaemia-reperfusion injury in the rat jejunum. Twenty four hour ligation of jejunal vasa brevia selectively induced ischaemic injury along the mesenteric margin. Two doses of indomethacin to rats did not induce greater injury than a single dose.

Conclusions—Results support the hypothesis that the rat jejunum possesses vascularly compromised sites along the mesenteric margin that are susceptible to indomethacin induced injury. Indomethacin may cause ischaemia-reperfusion injury selectively at these sites.
Macronutrient intake and malabsorption in HIV infection: a comparison with other malabsorptive states
Authors: Carbonnel F , Beaugerie L , Rached A Abou , D’Almagne H , Rozenbaum W , Le Quintrec Y , Gendre J P , Cosnes J
Published: June 2010

Background—Wasting is a major complication of HIV infection. The role of malabsorption in wasting is controversial.

Aims—To assess oral intake and malabsorption in a cohort of weight losing HIV infected patients, with or without chronic diarrhoea.

Methods—A prospective study using a predefined protocol for HIV infected patients was performed in a gastroenterology and nutrition unit in a university hospital. A retrospective comparison was made with HIV negative patients with malabsorption due either to small bowel disease or resection. Body weight and height, serum albumin, oral intake of macronutrients, faecal weight, and faecal fat were measured.

Results—Seventy nine weight losing HIV infected patients were studied. Among the 66 patients with more than 5% lipid malabsorption, wasting was significantly greater in patients with cryptosporidiosis (n=22) than in patients with microsporidiosis (n=18) who exhibited significantly more wasting than patients with no identified enteropathogen (n=26) (body mass index 16.8 (14.0–20.7), 18.9 (16.5–21.3), 19.7 (15.9–23), respectively). When controlling for the level of lipid malabsorption, HIV infected patients had a significantly lower energy intake than HIV negative patients with chronic malabsorption. In HIV infected patients, but not in other categories of malabsorbers, body mass index correlated significantly with energy intake (r=0.33, 95% confidence intervals 0.12 to 0.51).

Conclusion—In weight losing HIV infected patients, reduced energy intake is superimposed on malabsorption and significantly contributes to wasting.
A simple genetic test identifies 90% of UK patients with haemochromatosis
Authors:   The UK Haemochromatosis Consortium
Published: June 2010

Background—The diagnosis of genetic haemochromatosis (GH) before iron overload has developed is difficult. However a convincing candidate gene for GH, HFE (previously HLA-H), has been described recently.

Aims—To determine the prevalence of the haemochromatosis associated HFE mutations C282Y and H63D in United Kingdom affected and control populations.

Methods—The prevalence of the HFE C282Y and H63D mutations was determined by polymerase chain reaction amplification and restriction enzyme digestion in a cohort of 115 well characterised patients with GH and 101 controls from the United Kingdom.

Results—One hundred and five of 115 (91%) patients with GH were homozygous for the C282Y mutation. Only one of 101 (1%) controls was homozygous for the C282Y mutation and this individual currently shows evidence of iron overload. Two of five patients who did not have either of the two described mutations of HFE had early onset iron overload (ages 16 and 24). One had a family history of cardiac failure and the second was subsequently hospitalised due to cardiac failure. These are the first phenotypic observations for patients without either C282Y or H63D mutation of HFE.

Conclusion—This simple genetic test promises to be a highly effective tool in the diagnosis of GH.