bluuebunny/crossref_metadata_2025 huggingface dataset:
Fixed point theorems for semi‐groups of self maps of semi‐metric spaces
Authors: Jungck G.
Published: September 2002

We use selected semi‐groups of self maps of a semi‐metric space to obtain fixed point
theorems for single maps and for families of maps theorems which generalize results by Browder,
Jachymski, Rhoades and Waiters, and others. A basic tool in our approach is the concept of commuting
maps.
Some fixed point theorems for nonconvex spaces
Authors: Jafari F. , Sehgal V. M.
Published: September 2002

We give a theorem for nonconvex topological vector spaces which yields the
classical fixed point theorems of Ky Fan, Kim, Kaczynski, Kelly and Namioka as immediate
consequences, and prove a new fixed point theorem for set‐valued maps on arbitrary topological
vector spaces.
A note on some applications of semi‐open sets
Authors: Nour T. M.
Published: September 2002

The object of the present paper is to study the well known notions of semi‐closure, semiinterior,
semi‐frontier and semi‐exterior of a set using the concept of semi‐open sets. A semi‐isolated
point of a set is also defined and studied.
A subset of metric preserving functions
Authors: Vallin Robert W.
Published: September 2002

In this paper we define a subset of metric preserving functions and give some examples
and a characterization ofthis subset.
Rapid convergence of approximate solutions for first order nonlinear boundary value problems
Authors: Cabada Alberto , Nieto Juan J. , Heikkilä Seppo
Published: September 2002

In this paper we study the convergence of the approximate solutions for the following
first order problem

urn:x-wiley:01611712:media:ijmm387956:ijmm387956-math-0001

Here f : I × ℝ → ℝ is such that
exists and is a continuous function for some k ≥ 1. Under some
additional conditions on , we prove that it is possible to construct two sequences of approximate
solutions converging to a solution with rate of convergence of order k.
Linear feedback control of nonlinear systems with a dominating conservative quadratic term
Authors: Bose Anil , Cover Alan , Reneke James
Published: September 2002

Conditions are investigated for systems of the form Mx′ = N + Ax + f(x), where f is quadratic,
which lield a point dissipative system. Application of the conditions are made to the problem of
existence of linear feedback controls u = Kx for systems of the form

urn:x-wiley:01611712:media:ijmm782876:ijmm782876-math-0001

which force the system to be point dissipative. The basic results have eztensions to more general
classes of systems.
On the Cauchy problem for a degenerate parabolic differential equation
Authors: El-Fiky Ahmed
Published: September 2002

The aim of this work is to prove the existence and the uniqueness of the
solution of a degenerate parabolic equation. This is done using H. Tanabe and P.E.
Sobolevsldi theory.
On Dirichlet convolution method
Authors: Sukla Indulata
Published: September 2002

In this paper we have proved limitation theorem for (D, h(n))
summability methods and
have shown that it is best possible.
Regularization of distributions
Authors: Estrada Ricardo
Published: September 2002

We give a simple necessary and sufficient condition for the existence of distributional
regularizations. Our results apply to functions and distributions defined in the complement
of a point, in one or several variables. We also consider functions defined in the complement of a
hypersurface. We apply these results to the existence of distributional boundary values of harmonic
and analytic functions.
A general vector‐valued variational inequality and its fuzzy extension
Authors: Park Sehie , Lee Byung-Soo , Lee Gue Myung
Published: September 2002

A general vector‐valued variational inequality (GVVI) is considered. We establish the
existence theorem for (GVVI) in the noncompact setting, which is a noncompact generalization of the
existence theorem for (GVVI) obtained by Lee et al., by using the generalized form of KKM theorem due
to Park. Moreover, we obtain the fuzzy extension of our existence theorem.
Homogeneous cones and abelian theorems
Authors: Ostrogorski Tatjana
Published: September 2002

This paper deals with analysis on homogeneous cones in ℝn. This subject has its origins in
one‐dimensional topics that are connected, often implicitely, with some group properties. The homogeneous
cones are open convex cones in ℝn that are at the same time homogeneous spaces, and they are more general
than the classical, or symmetric cones. As an example of application of the theory of homogeneous cones we
study the asymptotic behaviour of some integral transforms.
Fixed points of a certain class of mappings in spaces with uniformly normal structure
Authors: Jung Jong Soo , Thakur Balwant Singh , Sahu Daya Ram
Published: September 2002

A fixed point theorem is proved in a Banach space E which has uniformly normal
structure for asymptotically regular mapping T satisfying:
for each x, y in the domain and for
n = 1, 2, ⋯,

urn:x-wiley:01611712:media:ijmm627507:ijmm627507-math-0001

where an, bn, cn are nonnegative constants satisfying certain conditions. This result generalizes a fixed
point theorem of Górnicki [1].
Common fixed points of biased maps of type (A) and applications
Authors: Pathak H. K. , Cho Y. J. , Kang S. M.
Published: September 2002

A generalization of compatible maps of type (A) called “biased maps of type (A)” is
introduced and used to prove fixed point theorems for certain contractions of four maps. Extensions
of known results are thereby obtained, i.e., the results of Pathak, Prasad, Jungck et al. are improved.
Some problems on convergence of self‐maps and fixed points are also discussed. Further, we use our
main results to show the existence of solutions of nonlinear integral equations.
Difference sequence spaces
Authors: Gaur A. K. , Mursaleen
Published: September 2002

In [1]

urn:x-wiley:01611712:media:ijmm654701:ijmm654701-math-0001

for r ≥ 1 is studied. In this paper, we generalize this space to Sr(p, Δ)
for a sequence of strictly positive
reals. We give a characterization of the matrix classes
(Sr(p, Δ), ℓ∞) and (Sr(p, Δ), ℓ1).
Generalization properties for certain analytic functions
Authors: Owa Shigeyoshi
Published: September 2002

The object ofthe present paper is to give some generalizations of results for certain
analytic functions which were proved by Saitoh (Math. Japon. 35 (1990), 1073‐1076). Our results
contain some corollaries as the special cases.
Visible point vector summations from hypercube and hyperpyramid lattices
Authors: Campbell Geoffrey B.
Published: September 2002

New identities are given, based on ideas related to visible (from the origin) point vectors. Each result was found from summing on vpv lattices dividing space
into radial regions from the origin. This is
related to recent work by the author in which new partition type infinite products were derived. Also
recently, Baake et al [3] and Mosseri [14] considered the 2‐D
visible lattice points as part of an optical
experiment in which the so‐called Optical Fourier Transform was applied. Many of the techniques
espoused in Glasser and Zucker [11], and in Ninham et al [15] involving Mellin and Möbius inversions
are applicable also to the current paper.
Codimension 2 fibrators that are closed under finite product
Authors: Im Young Ho , Kang Mee Kwang , Woo Ki Mun
Published: September 2002

In this paper, we show that if Nm is a closed manifold with hyperhopfian fundamental
group, πi(N) = 0 for 1 < i ≤ n
and Sn is a simply connected manifold, then Nm × Sn satisfies the
property that all proper, surjective maps from an orientable (n + 2)‐manifold M to a 2‐manifold B for
which each p−1(b) is homotopy equivalent to Nm × Sn necessarily are approximate fibrations.
A counter example on common periodic points of functions
Authors: Alikhani-Koopaei Aliasghar
Published: September 2002

By a counter example we show that two continuous functions defined on a
compact metric space satisfying a certain semi metric need not have a common periodic point.
Fixed point theorems for generalized Lipschitzian semigroups in Banach spaces
Authors: Thakur Balwant Singh , Jung Jong Soo
Published: September 2002

Fixed point theorems for generalized Lipschitzian semigroups are proved in p‐uniformly convex Banach spaces and in uniformly convex Banach spaces. As applications, its corollaries are given in a Hilbert space, in Lp spaces, in Hardy space Hp, and in Sobolev spaces Hk,p, for 1 < p < ∞ and k ≥ 0.
Oscillation of a higher order neutral difference equation with a forcing term
Authors: Thandapani E. , Manuel M. Maria Susai , Graef John R. , Spikes Paul W.
Published: September 2002

The authors obtain oscillation results for the even order forced
neutral difference equation

urn:x-wiley:01611712:media:ijmm494573:ijmm494573-math-0001

Examples illustrating the results are included.
A characterization of random approximations
Authors: Beg Ismat
Published: September 2002

By using Hahn‐Banach theorem, a characterization of random
approximations is obtained.
Weak convergence theorem for Passty type asymptotically nonexpansive mappings
Authors: Sharma B. K. , Thakur B. S. , Cho Y. J.
Published: September 2002

In this paper, we prove a convergence theorem for Passty type
asymptotically nonexpansive mappings in a uniformly convex Banach space with Fréchet‐differentiable norm.
Fixed points of rotations of n‐sphere
Authors: Prabhu Nagabhushana
Published: September 2002

We show that every rotation of an even‐dimensional sphere must
have a fixed point.
Mathematical approach and numerical analysis to the fundamental solutions method of Dirichlet problem
Authors: Inoue Tetsuo
Published: September 2002

Potentially theoretical schemes in the fundamental solutions
method will be proposed for Dirichlet problems of unbounded and bounded Jordan domains. The asymptotic theorem on extremal weighted polynomials will play fundamental roles to introduce a new scheme and to determine the distribution of charge points. Typical examples of the method will show that the numerical results of higher accuracy than those of the the conventional one
can be obtained.
s‐point finite refinable spaces
Authors: Davis Sheldon W. , Grabner Elise M. , Grabner Gray C.
Published: September 2002

A space X is called s‐point finite refinable (ds‐point finite refinable) provided every open cover 𝒰 of X has an open refinement 𝒱 such that, for some (closed discrete) C⫅X,

(i) for all nonempty V ∈ 𝒱, V∩C ≠ ∅ and

(ii) for all a ∈ C the set (𝒱)a = {V ∈ 𝒱 : a ∈ V} is finite.

In this paper we distinguish these spaces, study their basic
properties and raise several interesting questions. If λ is an ordinal with cf(λ) = λ > ω and S is a stationary subset of λ then S is not s‐point finite refinable. Countably compact ds‐point finite refinable spaces are compact. A space X is irreducible of order ω if and only if it is ds‐point finite refinable. If X is a strongly collectionwise Hausdorff ds‐point finite refinable space without isolated points then X is irreducible.
Strong Ditkin algebras without bounded relative units
Authors: Feinstein J. F.
Published: September 2002

In a previous note the author gave an example of a strong Ditkin
algebra which does not have bounded relative units in the sense of Dales. In this note we investigate a certain family of Banach function algebras on the one point compactification of ℕ, and see that within this family are many easier examples of strong Ditkin algebras without bounded relative units in the sense of Dales.
On the Ritt order and type of a certain class of functions defined by BE‐Dirichletian elements
Authors: Berland Marcel
Published: September 2002

We introduce the notions of Ritt order and type to functions
defined by the series

urn:x-wiley:01611712:media:ijmm201753:ijmm201753-math-0001

indexed by τ0 on R, where is a D‐sequence and is a sequence of entire functions of bounded index with at most a finite number of zeros. By definition, the series are BE‐Dirichletian elements. The notions of order and type of functions, defined by B‐Dirichletian elements, are considered in [3, 4]. In this paper, using a technique similar to that used by M. Blambert and M. Berland [6], we prove the same properties of Ritt order and type for these functions.
p‐topological Cauchy completions
Authors: Wig J. , Kent D. C.
Published: September 2002

The duality between “regular” and “topological” as convergence space properties extends in a natural way to the more general properties “p‐regular” and “p‐topological.” Since earlier papers have investigated regular, p‐regular, and topological Cauchy completions, we hereby initiate a study of p‐topological Cauchy completions. A p‐topological Cauchy space has a p‐topological completion if and only if it is “cushioned,” meaning that each equivalence class of nonconvergent Cauchy filters contains a smallest filter. For a Cauchy space allowing a p‐topological completion, it is shown that a certain class of Reed completions preserve the p‐topological property, including the Wyler and Kowalsky completions, which are, respectively, the finest and the coarsest p‐topological completions. However, not all p‐topological completions are Reed completions. Several extension theorems for p‐topological completions are obtained. The most interesting of these states that any Cauchy‐continuous map between Cauchy spaces allowing p‐topological and p′‐topological completions, respectively, can always be extended to a θ‐continuous map between any p‐topological completion of the first space and any p′‐topological completion of the second.
On a class of singular hyperbolic equation with a weighted integral condition
Authors: Mesloub Said , Bouziani Abdelfatah
Published: September 2002

In this paper, we study a mixed problem with a nonlocal condition
for a class of second order singular hyperbolic equations. We prove the existence and uniqueness of a strong solution. The proof is based on a priori estimate and on the density of the range of the operator generated by the studied problem.
Generalizations of Hardy′s integral inequalities
Authors: Bicheng Yang , Debnath Lokenath
Published: September 2002

This paper deals with some new generalizations of Hardy′s integral
inequalities. Some cases concerning whether the constant factors involved in these inequalities are best possible are discussed in some detail.
Inequalities via convex functions
Authors: Abou-Tair I. A. , Sulaiman W. T.
Published: September 2002

A general inequality is proved using the definition of convex functions. Many major inequalities are deduced as applications.
Stability for randomly weighted sums of random elements
Authors: Hu Tien-Chung , Chang Hen-Chao
Published: September 2002

Let {Xn : n = 1, 2, 3, …} be a sequence of i.i.d. random elements taking values in a separable Banach space of type p and let {An,i : i = 1, 2, 3, …; n = 1, 2, 3, …} be an array of random variables. In this paper, under various assumptions of {An,i}, the necessary and sufficient conditions for a.s. are obtained. Also, the necessity of the assumptions of {An,i} is discussed.
Some applications of a differential subordination
Authors: Kim Yong Chan , Srivastava H. M.
Published: September 2002

A number of interesting criteria were given by earlier workers for
a normalized analytic function to be in the familiar class 𝔖* of starlike functions. The main object of the present paper is to extend and improve each of these earlier results. An application associated with an integral operator 𝔉c(c > −1) is also considered.
Subsequences and category
Authors: Kallman Robert R.
Published: September 2002

If a sequence of functions diverges almost everywhere, then the set of subsequences which diverge almost everywhere is a residual set of subsequences.
The Abel‐type transformations into ℓ
Authors: Lemma Mulatu
Published: September 2002

Let t be a sequence in (0, 1) that converges to 1, and define the Abel‐type matrix Aα,t by for α > −1. The matrix Aα,t determines a sequence‐to‐sequence variant of the Abel‐type power series method of summability introduced by Borwein in [1]. The purpose of
this paper is to study these matrices as mappings into ℓ.
Necessary and sufficient conditions for Aα,t to be ℓ‐ℓ,G‐ℓ, and Gw‐ℓ are established. Also, the strength of Aα,t in the ℓ‐ℓ setting is investigated.
Double sequence core theorems
Authors: Patterson Richard F.
Published: September 2002

In 1900, Pringsheim gave a definition of the convergence of double sequences. In this paper, that notion is extended by presenting definitions for the limit inferior and limit superior of double sequences. Also the core of a double sequence is defined. By using these definitions and the notion of regularity for 4‐dimensional matrices, extensions, and variations of the Knopp Core theorem are proved.
A nonlocal parabolic system with application to a thermoelastic problem
Authors: Lin Y. , Tait R. J.
Published: September 2002

A system modeling the thermoelastic bards contacts is studied. The
problem is first transformed into an equivalent nonlocal parabolic systems using a transformation, and then the existence and uniqueness of the solutions are demonstrated via the theoretical potential representation theory of the parabolic equations. Finally some realistic situations in the applications are discussed using the results obtained in this paper.
Large solutions of semilinear elliptic equations with nonlinear gradient terms
Authors: Lair Alan V. , Wood Aihua W.
Published: September 2002

We show that large positive solutions exist for the equation (P±) : Δu ± |∇u|q = p(x)uγ in Ω⫅RN(N ≥ 3) for appropriate choices of γ > 1, q > 0 in which the domain Ω is either bounded or equal to RN. The nonnegative function p is continuous and may vanish on large parts of Ω. If Ω = RN, then p must satisfy a decay condition as |x| → ∞. For (P+), the decay condition is simply , where ϕ(t) = max|x|=tp(x). For (P−), we require that t2+βϕ(t) be bounded above for some positive β. Furthermore, we show that the given conditions on γ and p are nearly optimal for equation (P+) in that no large solutions exist if either γ ≤ 1 or the function p has compact support in Ω.
A simple characterization of commutative H*‐algebras
Authors: Saworotnow Parfeny P.
Published: September 2002

Commutative H*‐algebras are characterized without postulating
the existence of Hilbert space structure.
A note on the difference schemes for hyperbolic equations
Authors: Ashyralyev A. , Sobolevskii P. E.
Published: September 2002

The initial value problem for hyperbolic equations d 2u(t)/dt 2 + A u(t) = f(t)(0 ≤ t ≤ 1), u(0) = φ, u′(0) = ψ, in
a Hilbert space H is considered. The first and second order
accuracy difference schemes generated by the integer power of A
approximately solving this initial value problem are presented.
The stability estimates for the solution of these difference
schemes are obtained.
On the operator equation A X − X B = Cwith unbounded operators A, B, and C
Authors: Lan Nguyen Thanh
Published: September 2002

We find the criteria for the solvability of the operator equation
A X − X B = C, where A, B, and C are unbounded operators, and use the result to show existence and regularity of solutions of nonhomogeneous Cauchy problems.
Regularized functional calculi, semigroups, and cosine functionsfor pseudodifferential operators
Authors: Delaubenfels Ralph , Lei Yansong
Published: September 2002

Let iAj(1 ≤ j ≤ n) be generators of commuting bounded strongly continuous groups, A ≡ (A1, A2, …, An). We show that, when f has sufficiently many polynomially bounded derivatives, then there
exist k, r > 0 such that f(A) has a ‐regularized BCk(f(Rn)) functional calculus. This immediately produces regularized semigroups and cosine functions with an explicit representation; in particular, when f(Rn)⫅R, then, for appropriate k, r, is a Fourier‐Stieltjes transform, and when f(Rn)⫅[0, ∞), then is a Laplace‐Stieltjes transform. With A ≡ i(D1, …, Dn), f(A) is a pseudodifferential operator on Lp(Rn)(1 ≤ p < ∞) or BUC(Rn).
N‐Laplacian equations in ℝN with critical growth
Authors: B. do Ó João Marcos
Published: September 2002

We study the existence of nontrivial solutions to the following problem:

urn:x-wiley:10853375:media:aaa464613:aaa464613-math-0001

where a is a continuous function which is coercive, i.e., a(x) → ∞ as |x| → ∞
and the nonlinearity f behaves like exp(α|u|N/(N−1)) when |u| → ∞.
Existence of positive radial solutions for a weakly coupled system via blow up
Authors: García-Huidobro Marta , Guerra Ignacio , Manásevich Raúl
Published: September 2002

The existence of positive solutions to certain systems of ordinary differential equations is studied. Particular forms of these systems are satisfied by radial solutions of associated partial differential equations.
Uniform asymptotic normal structure, the uniform semi‐Opialproperty, and fixed points of asymptotically regular uniformly lipschitzian semigroups. Part II
Authors: Budzyńska Monika , Kuczumow Tadeusz , Reich Simeon
Published: September 2002

In this part of our paper we present several new theorems concerning the existence of common fixed points of asymptotically regular uniformly lipschitzian semigroups.
Analysis of a mathematical model related to Czochralski crystal growth
Authors: Knobloch Petr , Tobiska Lutz
Published: September 2002

This paper is devoted to the study of a stationary problem consisting of the Boussinesq approximation of the Navier–Stokes equations and two convection–diffusion equations for the temperature and concentration, respectively. The equations are considered in 3D and a velocity–pressure formulation of the Navier–Stokes equations is used. The problem is complicated by nonstandard boundary conditions for velocity on the liquid–gas interface where tangential surface forces proportional to surface gradients of temperature and concentration (Marangoni effect) and zero normal component of the velocity are assumed. The velocity field is coupled through this boundary condition and through the buoyancy term in the Navier–Stokes equations with both the temperature and concentration fields. In this paper a weak formulation of the problem is stated and the existence of a weak solution is proved. For small data, the uniqueness of the solution is established.
Critical groups of critical points produced by local linking with applications
Authors: Perera Kanishka
Published: September 2002

We prove the existence of nontrivial critical points with nontrivial critical groups for functionals with a local linking at 0. Applications to elliptic boundary value problems are given.
Solvability of a multi‐point boundary value problem of Neumann type
Authors: Gupta Chaitan P. , Trofimchuk Sergei
Published: September 2002

Let f : [0, 1] × ℝ2 → ℝ be a function satisfying Carathéodory′s conditions and e(t) ∈ L1[0, 1]. Let ξi ∈ (0, 1), ai ∈ ℝ, i = 1, 2, …, m − 2, 0 < ξ1 < ξ2 < ⋯<ξm−2 < 1 be given. This paper is concerned with the problem of existence of a solution for the m‐point boundary value problem . This paper gives conditions for the existence of a solution for this boundary value problem using some new Poincaré type a priori estimates. This problem was studied earlier by Gupta, Ntouyas, and Tsamatos (1994) when all of the ai ∈ ℝ, i = 1, 2, …, m − 2, had the same sign. The results of this paper give considerably better existence conditions even in the case when all of the ai ∈ ℝ, i = 1, 2, …, m − 2, have the same sign. Some examples are given to illustrate this point.
Different Forms of Vanadate on Sugar Transport in Insulin Target and Nontarget Cells
Authors: Germinario Ralph J. , Colby-Germinario Susan P. , Posner Barry I. , Nahm K.
Published: September 2002

The effects of several vanadates (ie, orthovanadate, pervanadate, and two stable peroxovanadium compounds) on basal and insulin‐stimulated 2‐DG transport in insulin target and nontarget cell lines are reported, herein. In nontarget cells,
exposure to vanadates (5 × 10−6
to 10−4
mol/L) resulted in 2‐DG transport stimulatory responses similar to those observed in 2‐DG transport post exposure to 667 nmol/L insulin alone, or insulin in combination with vanadates. In 3T3‐L1 adipocytes and L6 myotubes, exposure to a vanadate compound or 67 nmol/L insulin, stimulated 2‐DG transport dramatically. Again, this effect on stimulated transport was similar to 2‐DG transport post‐treatment with the effective vanadates in combination with insulin. While pervanadate or stable peroxovanadates stimulated 2‐DG transport at 10−5 to 10−6 mol/L, orthovanadate up to 10−4 mol/L was not effective in stimulating 2‐DG transport in any of the cell lines tested. The data indicate that the various peroxovanadates are clearly superior insulin mimetics while a more limited
insulin mimesis is observed with orthovanadate over a wide variety of cell types.
Angiotensinogen Gene Promoter Region Variant Modifies Body Size–Ambulatory Blood Pressure Relations in Hypertension
Authors: Tiago Armindo D. , Samani Nilesh J. , Candy Geoffrey P. , Brooksbank Richard , Libhaber Elena N. , Sareli Pinhas , Woodiwiss Angela J. , Norton Gavin R.
Published: September 2002

Background—

The extent to which genes modify the relationship between risk factors for hypertension and blood pressure (BP) is unclear. As angiotensinogen is expressed in adipose tissue and angiotensinogen (AGT) gene promoter variants influence the production of angiotensinogen, we evaluated the role of AGT gene variants as potential modifiers of body size–BP relations.

Methods and Results—

Five hundred twenty-one hypertensives of African origin sampled from a group with a high mean body mass index (BMI) had 24-hour ambulatory BP (ABP) measurements determined off therapy and were genotyped for the AGT –6G→A, –532C→T, –20A→C, and 704T→C (M235T) gene variants. Genotypes were also determined in 547 control subjects of African origin who had a normal clinic BP. The –6A and –532C alleles were concordant with the M235T variant. Although AGT gene variants had no independent effects on either the presence of hypertension or ABP values in hypertensives, the –20A→C polymorphism had a marked influence on the relation between ambulatory systolic BP and BMI. This relation was present in patients homozygous for the –20A allele (n=399,
r
=0.23,
P
<0.0001), but absent in those with at least one copy of the –20C allele (n=122,
r
=0.01,
P
=0.89). The M235T polymorphism did not impact on the BMI-BP relation. Specificity of the –20A→C polymorphism effect on the BMI-BP relation is further indicated by the lack of effect on the systolic BP–age relation.

Conclusion—

An AGT gene promoter region variant is an important modifier of the relation between body size and BP. Hence, these data corroborate the notion that genetic modifiers can produce a profound impact on BP-phenotypic relations.
Human Cardiac Inwardly-Rectifying K
+
Channel Kir
2.1b
Is Inhibited by Direct Protein Kinase C-Dependent Regulation in Human Isolated Cardiomyocytes and in an Expression System
Authors: Karle Christoph A. , Zitron Edgar , Zhang Wei , Wendt-Nordahl Gunnar , Kathöfer Sven , Thomas Dierk , Gut Bernd , Scholz Eberhard , Vahl Christian-Friedrich , Katus Hugo A. , Kiehn Johann
Published: September 2002

Background—

Protein kinases A (PKA) and C (PKC) are activated in ischemic preconditioning and heart failure, conditions in which patients develop arrhythmias. The native inward rectifier potassium current (IK
1
) plays a central role in the stabilization of the resting membrane potential and the process of arrhythmogenesis. This study investigates the functional relationship between PKC and IK
1
.

Methods and Results—

In whole-cell patch-clamp experiments with isolated human atrial cardiomyocytes, the IK
1
was reduced by 41% when the nonspecific activator of PKC phorbol 12 myristate 13-acetate (PMA; 100 nmol/L) was applied. To investigate the effects of PKC on cloned channel underlying parts of the native IK
1
, we expressed Kir
2.1b
heterologously in Xenopus oocytes and measured currents with the double-electrode voltage-clamp technique. PMA decreased the current by an average of 68%, with an IC
50
of 0.68 nmol/L. The inactive compound 4-α-PMA was ineffective. Thymeleatoxin and 1-oleolyl-2-acetyl-sn-glycerol, 2 specific activators of PKC, produced effects similar to those of PMA. Inhibitors of PKC, ie, staurosporine and chelerytrine, could inhibit the PMA effect (1 nmol/L) significantly. After mutation of the PKC phosphorylation sites (especially S64A and T353A), PMA became ineffective.

Conclusions—

The human IK
1
in atrial cardiomyocytes and one of its underlying ion channels, the Kir
2.1b
channel, is inhibited by PKC-dependent signal transduction pathways, possibly contributing to arrhythmogenesis in patients with structural heart disease in which PKC is activated.
Investigation into development of progressive-type variable lamination manufacturing using expandable polystyrene foam and its apparatus
Authors: Ahn D G , Lee S H , Yang D Y
Published: September 2002

In order to reduce the lead-time and cost, the technology of rapid prototyping (RP) has been widely used. However, RP techniques have disadvantageous characteristics according to their working principles: a low building speed caused by a thin-layer, stair-stepped surface of a part due to layer-by-layer stacking with a vertical edge, an additional post-processing and high cost for installation, operation and maintenance of the RP apparatus. The objective of this study is to propose a new RP process, progressive-type variable lamination manufacturing using expandable polystyrene foam (VLM-SP), to overcome the disadvantageous characteristics and to develop an apparatus for the implementation of the process. The proposed RP system employs several novel techniques such as a thick layer with the thickness less than 2 mm, a sloped surface with the first-order approximation between the top and bottom surfaces of each layer, a building sequence that performed stacking and bonding after cutting, the concept of a unit shape part (USP) and an automated synchronized four-axis hot-wire cutting system. In this paper, the characteristics of the proposed process and apparatus are discussed. The experiments are carried out to verify the bonding strength of the bonded area. Several three-dimensional shapes are fabricated on the prototype of the VLM-SP apparatus in order to investigate the applicability of the proposed process. In addition, in order to examine the efficiency of the VLM-SP process, the prototypes of VLM-SP are compared with those of commercial RP processes [LOM (laminated object manufacturing) and FDM (fused deposition modelling)] from the viewpoint of geometrical conformity, building time, building cost and dimensional accuracy. As a result of the comparison, it has been shown that the proposed process is an efficient rapid prototyping process.
Improving homework compliance in the treatment of generalized anxiety disorder
Authors: Leahy Robert L.
Published: September 2002

Generalized anxiety disorder is a chronic condition characterized by beliefs that worry prepares and protects, but that excessive worry is out of control. In this article, I review the cognitive‐behavioral model of generalized anxiety, focusing specifically on problems related to excessive worrying. Noncompliance in self‐help homework is reflected in the patient's excessive focus on negative feelings, difficulty identifying automatic thoughts, demand for immediate results, and the belief that worries are realistic. Interventions for these problems are illustrated in the case of the treatment of a patient characterized by persistent worries, low self‐confidence, procrastination, and avoidance. © 2002 Wiley Periodicals, Inc. J Clin Psychol/In Session 58: 499–511, 2002.
A study on observed evolution of boundary layer humidity distributions
Authors: Price Jeremy D.
Published: September 2002

Data are used from the Met Office tethered balloon facility to examine the evolution of boundary layer humidity probability density functions during various meteorological conditions. Results typically show significant changes in all four moments (mean, standard deviation, skewness and kurtosis) over periods from one to several hours. Boundary layers experiencing the greatest changes were normally convective in nature. In contrast, a quiescent wintertime boundary layer was seen to show very little evolution over a period of two days. Models which use statistical distributions of humidity for cloud prediction should ideally be able to reproduce these observations. Copyright © 2002 British Crown Copyright.
Biogeophysical impacts of land use on present‐day climate: near‐surface temperature change and radiative forcing
Authors: Betts Richard A.
Published: September 2002

Changes in land cover affect climate through the surface energy and moisture budgets, but these biogeophysical impacts of land use have not yet been included in General Circulation Model (GCM) simulations of 20th century climate change. Here, the importance of these effects was assessed by comparing climate simulations performed with current and potential natural vegetation. The northern mid‐latitude agricultural regions were simulated to be approximately 1–2 K cooler in winter and spring in comparison with their previously forested state, due to deforestation increasing the surface albedo by approximately 0.1 during periods of snow cover. Some other regions such as the Sahel and India experienced a small warming due to land use. Although the annual mean global temperature is only 0.02 K lower in the simulation with present‐day land use, the more local temperature changes in some regions are of a similar magnitude to those observed since 1860. The global mean radiative forcing by anthropogenic surface albedo change relative to the natural state is simulated to be −0.2 Wm2, which is comparable with the estimated forcings relative to pre‐industrial times by changes in stratospheric and tropospheric ozone, N2O, halocarbons, and the direct effect of anthropogenic aerosols. Since over half of global deforestation has occurred since 1860, simulations of climate since that date should include the biogeophysical effects of land use. Copyright © 2001 British Crown Copyright.
The effect of insulin on proteins associated with free, cytoskeletal‐bound and membrane‐bound polysome populations.
Authors: Moss Rigmor , Pryme Ian F. , Vedeler Anni
Published: September 2002

It is known that insulin treatment increases the rate of protein synthesis in many cells and tissues and that it causes changes in the distribution of ribosomes between free (FP), cytoskeletal‐bound (CBP) and membrane‐bound polysome (MBP) populations. This paper concerns an analysis of the pattern of proteins in high‐salt extracts of FP, CBP and MBP isolated from Krebs II ascites and MPC‐11 cells. A combined detergent/salt extraction procedure was used to isolate the three fractions of polysomes from control cells and from cells following short‐term stimulation with insulin. There were differences in the protein patterns in the individual fractions and changes occurred after insulin stimulation.
Carbohydrate metabolism of lung tissue of suckling and adult rats.
Authors: Maritz G. S.
Published: September 2002

The carbohydrate metabolism of lung tissue of suckling (1‐3 weeks) and adult (40‐42 weeks) rats were investigated and compared. The results showed that the apparent km for in vitro glucose utilization was 3,13 mM for adult lung and the V max 136,99 μmol/g/h. This could not be determined for neonatal animals. The rate of glucose entry into the glycolytic pathway of adult lung was faster than in the lung of neonatal rats. However, glycogen utilization by neonatal lung was faster than by adult lung. The in vitro oxygen consumption of the lung tissue slices of both age groups were the same. It is proposed that the slower rate of glucose entry into glycolysis in lung tissue of suckling rats is due to a different hexokinase isoenzyme profile. It is also concluded that glycogen‐glucose plays a major role in lung development.
The role of growth factors in gastrointestinal cell proliferation.
Authors: Alison Malcolm R. , Sarraf Catherine E.
Published: September 2002

The epithelial lining of the gastrointestinal (GI) tract is in a state of continuous cell renewal, and the proliferating and differentiating/differentiated cell populations are spatially clearly demarcated. Members of the epidermal growth factor (EGF) family of peptides, the trefoil peptides and enteroglucagon appear to be the most important enterotrophic molecules for both normal cell renewal and healing after cell damage. Transforming growth factor‐a (TGF‐a) appears to be the primary physiological ligand for the EGF receptor (EGFR), promoting normal cell renewal, and TGF‐a/EGFR are part of an autocrine loop in many intestinal cancers. In response to damage, a differentiating cell lineage arises from adjacent epithelium secreting EGF, TGF‐a and trefoil peptides; this may be viewed as part of a ‘repair kit’ in damaged endodermally‐derived tissue.
A 170 kDa polypeptide from mung bean shares multiple epitopes with rabbit skeletal myosin and binds ADP‐adpagarose
Authors: Qiao Lin , Jablonsky Peter P. , Elliott Janet , Williamson Richard E.
Published: September 2002

A 170 kDa polypeptide that has been partially purified from mung beans is retained by ADPagarose even in the absence of divalent cations when most non‐myosin ATPases and kinases do not bind. Attempts to demonstrate a myosin‐like ATPase activity were inconclusive, however, and the protein accounts at most for only a small part of the total K+ EDTA ATPase activity of mung bean extracts. All four monoclonal antibodies raised to the 170 kDa polypeptide react with rabbit skeletal muscle myosin and localize the 170 kDa polypeptide in mung bean root tip cells to the actin‐containing phragmoplast and to sites dispersed throughout the cytoplasm which probably include some but not all actin cables. These 4 monoclonals and 3 commercially available antimyosin monoclonals all recognise rabbit skeletal myosin and 160‐170 kDa proteins that are present in two other angiosperms tested. In addition, a 158 kDa protein of mung bean reacts with only one antibody and does not bind ADP‐agarose. We conclude that strong but not yet conclusive evidence points to the 160‐170 kDa proteins of angiosperms being a widely conserved form of myosin heavy chain.
Gelatinases and metalloproteinase inhibitor secreted by murine colonic carcinoma cells with differing metastatic potential
Authors: Kishi Jun‐Ichi , Tanaka Rie , Koiwai Osamu , Yamagata Sadako , Numata Yukiko , Hayakawa Taro , Shimizu Satoru
Published: September 2002

Gelatinase activity and inhibitory activity against collagenase were measured in serum‐free medium conditioned by murine colonic carcinoma cells with different spontaneous metastatic potentials to the lung. The medium conditioned with poorly metastatic NM11 cells gave higher inhibitory activity than that conditioned with highly metastatic LuM1 cells, while the level of secreted gelatinases in the same medium was lower in NM11 medium than in LuM1 case. Northern analysis showed the higher gene expression of both tissue inhibitor of metalloproteinases (TIMP)‐1 and TIMP‐2 in NM11 cells than in LuM1 cells, suggesting that both TIMPs are responsible for the increase of inhibitory activity in NM11 conditioned medium. Examination of the balance of gelatinases and inhibitor revealed that the amount of inhibitor exceeded that of gelatinases in the medium conditioned with NM11 cells. In contrast, the medium conditioned with LuM1 cells contained excess amounts of gelatinases. The results indicated a close correlation between the balance of gelatinases and inhibitors and the metastatic behavior of murine tumor cells.
Calcium‐activated chloride fluxes in cultured NCL‐SG3 sweat gland cells
Authors: Ring Avi , Mörk Ann‐Christin , Roomans Godfried M.
Published: September 2002

The dependence of chloride permeability of the human sweat gland cell line NCL‐SG3 cell line on cytosolic free calcium ([Ca2+]i) was investigated. X‐ray microanalysis, fura‐2 fluorescence and patch clamp methodology were used. Carbachol and A23187 decreased cellular Cl and K for cells grown on permeable supports, but carbachol had no effect on cells grown on impermeable supports. In perforated patch experiments with impermeable supports, ATP and calcium ionophores increased the inward current (ic) whereas carbachol had no effect. ic was unaffected by cation channel blockers or removal of extracellular Na+ but was blocked by chloride channel blockers. Lowering bath Ca2+ decreased ic. On raising bath Ca2+ ic and [Ca2+]i responded with a transient rise which was not blocked by La3+ or D‐600. La3+, but not D‐600, blocked the entry of Mn2+. K+‐depolarization and Bay‐K‐8644 had little effect on [Ca2+]i. The rise in [Ca2+]i may be mediated primarily via depletion operated Ca2+‐channels. Irrespective of substrate NCL‐SG3 cells have a chloride permeability which depends on [Ca2+]i.
The epidermal growth factor.
Authors: Boonstra Johannes , Rijken Philip , Humbel Bruno , Cremers Fons , Verkleij Arie , en Henegouwen Paul van Bergen
Published: September 2002

Epidermal growth factor (EGF) is a single polypeptide of 53 amino acid residues which is involved in the regulation of cell proliferation. Egf exerts its effects in the target cells by binding to the plasma membrane located EGF receptor. The EGF receptor is a transmembrane protein tyrosine kinase. Binding of EGF to the receptor causes activation of the kinase and subsequently receptor autophosphorylation. The autophosphorylation is essential for the interaction of the receptor with its substrates. These bind to the receptor by the so‐called SH2 domains.

The signal transduction pathways activated by EGF include the phosphatidylinositol pathway, leading to activation of protein kinase C and to increase in the intracellular Ca2+ concentration, and to the ras pathway leading to MAP kinase activation.

Recently the cytoplasm has been implicated as playing an important role in EGF induced signal transduction. The EGF receptor has been demonstrated to be an actin‐binding protein. In addition EGF causes a rapid actin depolymerisation and the formation of membrane ruffles. In particular these membrane ruffles have been shown to act as the first site of signal transduction after EGF binding, and thus may be considered as signal transduction structures. Finally evidence has been presented suggesting a positive role for EGF and/or the receptor in the nucleus.
Regulation of fibronectin expression by PDGF‐BB And IGF‐I in cultured rat thoracic aortic adventitial fibroblasts.
Authors: Zhang Jing , Lo Chu‐shek
Published: September 2002

Regulation of fibronectin (FN) by Platelet‐derived Growth Factor‐BB (PDGF‐BB) and Insulin‐like Growth Factor‐I (IGF‐I) in cultured rat thoracic aortic adventitial fibroblasts were examined. PDGF‐BB enhances FN mRNA levels in a time and concentration‐dependent fashion. The effect of IGF‐I on PDGF‐BB‐induced FN levels was also examined. There was a larger increase in FN mRNA levels (4‐fold) in the cells treated with both IGF‐I and PDGF‐BB than with either IGF‐I (2‐fold) or PDGF‐BB (2‐fold) alone. The effects of PDGF‐BB and IGF‐I on FN levels were examined. There was a larger increase in FN levels (135%) in the cells treated with both PDGF‐BB and IGF‐I than with either PDGF‐BB (43%) or IGF‐I (45%) alone. Regulation of adventitial fibroblast FN may lead to blood vessel diseases and/or angiogenesis.
Early endocytotic steps in elicited macrophages: omega‐shaped plasma membrane vesicles at their cell surface.
Authors: Kiss Anna L. , Kittel Agnes
Published: September 2002

Fluid‐phase and receptor‐mediated endocytosis were studied in Freund's adjuvant elicited macrophages. These cells were found to bind and internalize significantly larger amounts of peroxidase‐antiperoxidase (PAP) immune complex than resident macrophages. Similarly the rate of the fluid‐phase uptake was higher in elicited cells. When studying the early steps of endocytotic processes, omega‐shaped plasma membrane pits (d∼90 nm) were found at the macrophage cell surface. Although occurring occasionally in resident cells, their number was highly increased after elicitation in 30% of the macrophage cell population. The different morphology of these cells coincided with a lower endocytotic activity and a very strong ecto Ca2+‐ATPase reaction. The present findings indicate that the elicited macrophage population is heterogenous and consists of different subclasses.
Studies on the permeability of the blood‐testis barrier in stainless steel‐administered mice
Authors: Pereira M. L.
Published: September 2002

Previous trials performed in our laboratory have demonstrated that stainless steel corrosion products induced morphological changes in mice seminiferous cells. In this study the functional nature of the blood‐testis barrier was investigated, in view of the extesive use of this metallic alloy in orthopaedic surgery. The uptake of horseradish peroxidase by the seminiferous tubules was used as a tracer method being exposed in vitro for different periods of time and observed at the ultrastructural level. Both boundary cells as well as Sertoli cells of experimental group absorbed the tracer, as manifested by vesicles and vacuoles filled with the reaction product, evidencing its role within the testis. Germ cells were also able in the uptake of this macromolecule. However, the tracer did not spread into the junctional complexes between neighboring Sertoli cells, at any interval of time used in this study, demonstrating the functional integrity of this barrier.
HUMAN CHROMOSOME Y AND SRY
Authors: SHAH V. C. , SMART VAISHALI
Published: September 2002

The precise location of the SRY gene on the human Y chromosome has been revealed through studies of sex reversal cases involving deletion, cross‐linking and mutations of the SRY gene. Its DNA sequence and mechanism of action are being understood. Similarity of SRY with Sry of mice and its interaction with other genes in male sex determination are discussed.
STRUCTURE—FUNCTION RELATIONSHIPS OF NA+/K+‐PUMPS EXPRESSED INXENOPUSOOCYTES
Authors: SCHWARZ WOLFGANG , VASILETS LARISA A.
Published: September 2002

During the last years we have examined structure—function relationships in the Na+/K+‐ATPase with respect to interactions of the external cations with the pump molecule. We have analysed in voltage‐clamp experiments the influence of extracellular Na+and K+on the current generated by Na+/K+‐pumps expressed inXenopusoocytes. Our results demonstrated that external Na+and K+have to pass an access channel in the electrical field of the membrane to reach their binding sites. This external access, therefore, is voltage‐dependent and is affected by lysine residues within the cytoplasmic N‐terminus, by glutamic acid residues in intramembraneous domains, the ouabain sensitivity and phosphorylation by protein kinases.
STIMULATION OF COLLAGEN SYNTHESIS IN RAT CARDIAC FIBROBLASTS BY EXPOSURE TO HYPOXIC CULTURE CONDITIONS AND SUPPRESSION OF THE EFFECT BY NATRIURETIC PEPTIDES
Authors: TAMAMORI MIMI , ITO HIROSHI , HIROE MICHIAKI , MARUMO FUMIAKI , HATA RYU‐ICHIRO
Published: September 2002

Synthesis of type I and type III collagens by rat cardiac fibroblasts was stimulated when the cells were cultured under 95% N2/5% CO2for one hour followed by incubation under normoxic conditions for 24 hours. The stimulative effect was attenutated by the presence of atrial natriuretic peptide (ANP, 10−6m) or brain natriuretic peptide (BNP, 10−6m) in the culture medium. Northern blot analysis indicated that α1(I) and α1(III) collagen mRNA levels were also increased by hypoxia, and decreased with the addition of ANP or BNP in a dose‐dependent manner. These results indicate interaction between intracellular signals of a physical stimulus (hypoxic stress) and those of a chemical one (ANP or BNP) and demonstrate that both signals regulate collagen synthesis by cardiac fibroblasts at the levels of the mRNAs. The results also suggest that natriuretic peptides produced by cardiomyocytes in vivo may function as paracrine factors that play a role in the prevention of cardiac fibrosis in ischaemic heart diseases.