bluuebunny/crossref_metadata_2025_split huggingface dataset:
Parity results for certain partition functions and identities similar to theta function identities
Authors: Blecksmith Richard , Brillhart John , Gerst Irving 
Published: June 2010

In this paper we give a collection of parity results for partition functions of the form
\[

∏

n
∈
S

(
1
−

x
n

)

−
1

≡

∑

−
∞

∞

x

e
(
n
)

(
mod

2
)

\prod _{n \in S} (1 - x^n)^{-1} \equiv \sum _{-\infty }^\infty x^{e(n)} \pmod 2

\]
and
\[

∏

n
∈
S

(
1
−

x
n

)

−
1

≡

∑

−
∞

∞

(

x

e
(
n
)

+

x

f
(
n
)

)

(
mod

2
)

\prod _{n \in S} (1 - x^n)^{-1} \equiv \sum _{-\infty }^\infty (x^{e(n)} + x^{f(n)})\pmod 2

\]
for various sets of positive integers S, which are specified with respect to a modulus, and quadratic polynomials

e
(
n
)

e(n)

and

f
(
n
)

f(n)

. Several identities similar to theta function identities, such as
\[

∏

n
=
1

n

≢

±
(
4
,
6
,
8
,
10
)

(
mod

32
)

∞

(
1
−

x
n

)
=
1
+

∑

n
=
1

∞

(
−
1

)
n

(

x

n
2

+

x

2

n
2

)
,

\prod _{\substack {n = 1\\n \nequiv \pm (4,6,8,10)\pmod {32}}}^\infty (1 - x^n) = 1 + \sum _{n = 1}^\infty (-1)^n (x^{n^2} + x^{2 n^2}),

\]
and its associated congruence
\[

∏

n
=
1

n

≢

0
,
±
2
,
±
12
,
±
14
,
16

(
mod

32
)

∞

(
1
−

x
n

)

−
1

≡
1
+

∑

n
=
1

∞

(

x

n
2

+

x

2

n
2

)

(
mod

2
)
,

\prod _{\substack {n = 1\\n \nequiv 0, \pm 2, \pm 12, \pm 14,16 \pmod {32}}}^\infty (1 - x^n)^{-1} \equiv 1 + \sum _{n = 1}^\infty (x^{n^2} + x^{2 n^2}) \pmod 2,

\]
are also proved.
Superconvergence of a collocation-type method for simple turning points of Hammerstein equations
Authors: Kumar Sunil 
Published: June 2010

In this paper a simple turning point (

y
=

y
c

y = {y^c}

,

λ
=

λ
c

\lambda = {\lambda ^c}

) of the parameter-dependent Hammerstein equation
\[

y
(
t
)
=
f
(
t
)
+
λ

∫
a
b

k
(
t
,
s
)
g
(
s
,
y
(
s
)
)

d
s
,

t
∈
[
a
,
b
]
,

y(t) = f(t) + \lambda \int _a^b {k(t,s)g(s,y(s))\;ds,\quad t \in [a,b],}

\]
is approximated numerically in the following way. A simple turning point (

z
=

z
c

z = {z^c}

,

λ
=

λ
c

\lambda = {\lambda ^c}

) of an equivalent equation for

z
(
t
)
:=
λ
g
(
t
,
y
(
t
)
)

z(t):=\lambda g(t,y(t))

is computed first. This is done by solving a discretized version of a certain system of equations which has (

z
c

{z^c}

,

λ
c

{\lambda ^c}

) as part of an isolated solution. The particular discretization used here is standard piecewise polynomial collocation. Finally, an approximation to

y
c

{y^c}

is obtained by use of the (exact) equation
\[

y
(
t
)
=
f
(
t
)
+

∫
a
b

k
(
t
,
s
)
z
(
s
)

d
s
,

t
∈
[
a
,
b
]
.

y(t) = f(t) + \int _a^b {k(t,s)z(s)\;ds,\quad t \in [a,b].}

\]
The main result of the paper is that, under suitable conditions, the approximations to

y
c

{y^c}

and

λ
c

{\lambda ^c}

are both superconvergent, that is, they both converge to their respective exact values at a faster rate than the collocation approximation (of

z
c

{z^c}

) does to

z
c

{z^c}

.
Numerical approximation of a wave equation with unilateral constraints
Authors: Schatzman Michelle , Bercovier Michel 
Published: June 2010

The system

u

t
t

−

u

x
x

∍
f

{u_{tt}} - {u_{xx}} \backepsilon f

,

x
∈
(
0
,
L
)
×
(
0
,
T
)

x \in (0,L) \times (0,T)

, with initial data

u
(
x
,
0
)
=

u
0

(
x
)

u(x,0) = {u_0}(x)

,

u
t

(
x
,
0
)
=

u
1

(
x
)

{u_t}(x,0) = {u_1}(x)

almost everywhere on (0, L) and boundary conditions

u
(
0
,
t
)
=
0

u(0,t) = 0

, for all

t
≥
0

t \geq 0

, and the unilateral condition
\[

u
x

(
L
,
t
)
≥
0
,
u
(
L
,
t
)
≥

k
0

,
(
u
(
L
,
t
)
−

k
0

)

u
x

(
L
,
t
)
=
0

{u_x}(L,t) \geq 0,u(L,t) \geq {k_0},(u(L,t) - {k_0}){u_x}(L,t) = 0

\]
models the longitudinal vibrations of a rod, whose motion is limited by a rigid obstacle at one end. A new variational formulation is given; existence and uniqueness are proved. Finite elements and finite difference schemes are given, and their convergence is proved. Numerical experiments are reported; the characteristic schemes perform better in terms of accuracy, and the subcharacteristic schemes look better.
Noninterpolatory integration rules for Cauchy principal value integrals
Authors: Rabinowitz P. , Lubinsky D. S. 
Published: June 2010

Let

w
(
x
)

w(x)

be an admissible weight on

[
−
1
,
1
]

[ - 1,1]

and let

{

p
n

(
x
)

}
0
∞

\{ {p_n}(x)\} _0^\infty

be its associated sequence of orthonormal polynomials. We study the convergence of noninterpolatory integration rules for approximating Cauchy principal value integrals
\[

I
(
f
;
λ
)
:=
∮
w
(
x
)

f
(
x
)

x
−
λ

d
x
,

λ
∈
(
−
1
,
1
)
.

I(f;\lambda ):=\oint w(x)\frac {{f(x)}}{{x - \lambda }}\,dx,\quad \lambda \in ( - 1,1).

\]
This requires investigation of the convergence of the expansion
\[

I
(
f
;
λ
)
∼

∑

k
=
0

∞

(
f
,

p
k

)

q
k

(
λ
)
,

λ
∈
(
−
1
,
1
)
,

I(f;\lambda ) \sim \sum \limits _{k = 0}^\infty {(f,{p_k}){q_k}(\lambda ),\quad \lambda \in ( - 1,1),}

\]
in terms of the functions of the second kind

{

q
k

(
λ
)

}
0
∞

\{ {q_k}(\lambda )\} _0^\infty

associated with w, where
\[

(
f
,

p
k

)
:=

∫

−
1

1

w
(
x
)
f
(
x
)

p
k

(
x
)

d
x

and

q
k

(
λ

)
:=
∮
w
(
x
)

p
k

(
x
)

x
−
λ

d
x
,

(f,{p_k}):=\int _{ - 1}^1 {w(x)f(x){p_k}(x)\,dx\quad {\text {and}}\quad {q_k}(\lambda } ):=\oint w(x)\frac {{{p_k}(x)}}{{x - \lambda }}\,dx,

\]

k
=
0
,
1
,
2
,
…
,
λ
∈
(
−
1
,
1
)

k = 0,1,2, \ldots ,\lambda \in ( - 1,1)

.
Effective bounds for the maximal order of an element in the symmetric group
Authors: Massias Jean-Pierre , Nicolas Jean-Louis , Robin Guy 
Published: June 2010

Let

σ
n

\sigma _n

be the symmetric group of n elements and
\[

g
(
n
)
=

max

σ
∈

σ
n

(

order of

σ

)
.

g(n) = \max _{\sigma \in \sigma _n}(\text {order of $\sigma $} ).

\]
We give here some effective bounds for

g
(
n
)

g(n)

and

P
(
g
(
n
)
)

P(g(n))

(greatest prime divisor of

g
(
n
)

g(n)

). Theoretical proofs are in "Evaluation asymptotique de l’ordre maximum d’un élément du groupe symétrique" (Acta Arith., v. 50, 1988, pp. 221-242). The tools used here are techniques of superior highly composite numbers of Ramanujan and bounds of Rosser and Schoenfeld on the Chebyshev function

θ
(
x
)

\theta (x)

.
Approximations for weakly nonlinear evolution equations
Authors: Miklavčič Milan 
Published: June 2010

Convergence of approximations for a large class of weakly nonlinear parabolic and hyperbolic equations is proven. The main emphasis is on proving convergence of finite element and spectral Galerkin approximations of solutions to the weakly nonlinear wave equation
\[

u
(
t
)
+
A
u
(
t
)
=
F
(
t
,
u
(
t
)
,

u
′

(
t
)
)
,

u
(
0
)
=

x
0

,

u
′

(
0
)
=

y
0

,

u(t) + Au(t) = F(t,u(t),u’(t)),\quad u(0) = {x_0},u’(0) = {y_0},

\]
under minimal assumptions on the linear operator A and on the approximation spaces. A can be a very general elliptic operator (not just of 2nd order and not necessarily in a bounded domain); A can also be very singular and degenerate. The results apply also to systems of equations. Verification of the hypotheses is completely elementary for a large class of problems.
Effector‐triggered innate immunity contributes Arabidopsis resistance to Xanthomonas campestris
Authors: RONG WEI , FENG FENG , ZHOU JIANMIN , HE CHAOZU 
Published: June 2010

SUMMARY Xanthomonas campestris pv. campestris, the causal agent of black rot disease, depends on its type III secretion system (TTSS) to infect cruciferous plants, including Brassica oleracea, B. napus and Arabidopsis. Previous studies on the Arabidopsis–Pseudomonas syringae model pathosystem have indicated that a major function of TTSS from virulent bacteria is to suppress host defences triggered by pathogen‐associated molecular patterns. Similar analyses have not been made for the Arabidopsis–X. campestris pv. campestris pathosystem. In this study, we report that X. campestris pv. campestris strain 8004, which is modestly pathogenic on Arabidopsis, induces strong defence responses in Arabidopsis in a TTSS‐dependent manner. Furthermore, the induction of defence responses and disease resistance to X. campestris pv. campestris strain 8004 requires NDR1 (NON‐RACE‐SPECIFIC DISEASE RESISTANCE1), RAR1 (required for Mla12 resistance) and SGT1b (suppressor of G2 allele of skp1), suggesting that effector‐triggered immunity plays a large role in resistance to this strain. Consistent with this notion, AvrXccC, an X. campestris pv. campestris TTSS effector protein, induces PR1 expression and confers resistance in Arabidopsis in a RAR1‐ and SGT1b‐dependent manner. In rar1 and sgt1b mutants, AvrXccC acts as a virulence factor, presumably because of impaired resistance gene function.
p53‐dependent G1 arrest in 1st or 2nd cell cycle may protect human cancer cells from cell death after treatment with ionizing radiation and Chk1 inhibitors
Authors: Petersen L. , Hasvold G. , Lukas J. , Bartek J. , Syljuåsen R. G. 
Published: June 2010

AbstractObjectives:  This study was performed to explore the strategy of combining Chk1 inhibitors with ionizing radiation (IR) to selectively target p53‐deficient cancer cells.Materials and methods:  Survival and cell cycle progression were measured in response to IR and the Chk1 inhibitors, UCN‐01 and CEP‐3891, in colon carcinoma HCT116 p53+/+ and p53−/− cells, and in osteosarcoma U2OS‐VP16 cells with conditional expression of dominant‐negative p53 (p53DD).Results:  Clonogenic survival was selectively reduced in HCT116 p53−/− compared to p53+/+ cells after treatment with UCN‐01 and IR, and HCT116 p53+/+ cells also displayed strong p53‐dependent G1 arrest in the 1st cell cycle after IR. In contrast, clonogenic survival was affected similarly in U2OS‐VP16 cells with and without expression of p53DD. However, death of U2OS‐VP16 cells was p53 dependent as assessed by cell viability assay at 72 h, and this was associated with p53‐dependent G1 arrest in the 2nd cell cycle after treatment. Notably, HCT116 cells were overall more resistant than U2OS cells to cytotoxic effects of Chk1 inhibitors.Conclusion:  Our results suggest that p53‐dependent G1 arrest in both 1st and 2nd cell cycles may protect human cancer cells from cell death after treatment with IR and Chk1 inhibitors. However, a challenge for future clinical use will be that different cancers display different intrinsic sensitivity to such inhibitors.
Differential proteome and phosphoproteome signatures in human T‐lymphoblast cells induced by sirolimus
Authors: Schultze F. C. , Petrova D. T. , Oellerich M. , Armstrong V. W. , Asif A. R. 
Published: June 2010

AbstractObjectives:  The present study was designed to investigate early proteome and phosphoproteome changes during inhibition of lymphocyte proliferation induced by sirolimus (SRL).Materials and methods:  Proliferation assays were conducted using human CCRF‐CEM T lymphoblasts under different SRL concentrations. Total protein lysates after SRL treatment were used to identify significantly regulated proteins and phosphorylated proteins by 2‐DE and Q‐TOF Ultima Global mass spectrometer.Results and conclusions:  Incubation with 2.5 μmol/l SRL resulted in a ∼ 70% inhibition of cell proliferation. Cells incubated with 2.5 μmol/l for 30 min showed a differential phosphorylation pattern with one higher (TCPQ) and six lower phosphorylation signals (TBA1B, VIME, HNRPD, ENPL, SEPT9, PLSL). On investigating the differential protein expression, five proteins were found to be up‐regulated (ECHB, PSB3, MTDC, LDHB and NDKA) and four were down‐regulated (EHD1, AATC, LMNB1 and MDHC). Nine of these differentially regulated proteins/phosphoproteins (TCPQ, TBA1B, VIME, HNRPD, ENPL, ECHB, PSB3, LDHB and LMNB1) showed significant interaction potential, through binding protein YWHAZ using MINT software.Conclusions:  We report for the first time the simultaneous early influence of SRL on phosphorylation status and on protein expression in the total proteome of CCRF‐CEM T lymphoblasts and predict that 56% of the proteins interact with each other, highlighting significance of these results.
Percentage of positive biopsies predicts lymph node involvement in men with low‐risk prostate cancer undergoing radical prostatectomy and extended pelvic lymphadenectomy
Authors: Heidenreich Axel , Pfister David , Thüer David , Brehmer Bernhard 
Published: June 2010

Study Type – Diagnostic (exploratory cohort) Level of Evidence 2b What’s known on the subject? and What does the study add? The current retrospective study evaluates predictive clinical parameters associated with lymph node metastasis in a homogeneous cohort of 499 men with low‐risk prostate cancer who underwent radical prostatectomy. Low‐risk profile and <50% of biopsies involved with cancer are strong predictors of metastasis‐free lymph nodes so that patients do not have to undergo extended pelvic lymphadenectomy.OBJECTIVETo evaluate preoperative predictive risk factors associated with lymph node metastases (LNM) in a cohort of low‐risk prostate cancer (PCA) patients.PATIENTS AND METHODSThe charts of 499 patients were retrospectively reviewed to identify prognostic risk factors for the presence of LNM. Pathohistological data and Gleason score of the radical prostatectomy (RP) specimen, number of removed nodes, number of positive lymph nodes, and anatomical distribution of LNM were tabulated and evaluated. A correlation between clinical stage, preoperative serum prostate‐specific antigen (PSA), biopsy Gleason score, number of biopsies taken, percentage of positive biopsies and the presence of LNM were calculated. All 499 men underwent retropubic RP and extended pelvic lymphadenectomy (EPLND).RESULTSLNM were identified in 29 (5.8%) patients. A prediction model based on clinical stage, PSA, and biopsy Gleason score had a predictive accuracy of 79.2%. The addition of number of positive biopsies and % positive cores improved its predictive accuracy to 81.5% and 87.8%, respectively. The predicted frequency of LNM by the original nomogram was 7.4% and differed by less than 3% with the actual observation of LNM. The predictive accuracy of the nomogram was 81.5% as compared with 87.8% of the prediction model of this study.CONCLUSIONSThe percentage of positive cores involved with PCA is the most reliable predictor of LNM and indicates the need for EPLND. The Briganti nomogram has been validated and a general applicability for predicting the presence of LNM was proven.
Cardiovascular dysautonomia in de novo Parkinson’s disease without orthostatic hypotension
Authors: Oka H. , Toyoda C. , Yogo M. , Mochio S. 
Published: June 2010

Background:  Clinical symptoms of Parkinson’s disease (PD) include not only motor distress, but also autonomic dysfunction.Objective:  To study the characteristics of subclinical autonomic nervous dysfunction in de novo PD without orthostatic hypotension (OH).Methods:  Autonomic nervous function including cardiac sympathetic gain was evaluated on the basis of cardiac radioiodinated metaiodobenzylguanidine (MIBG) uptake, the response to the Valsalva maneuver, and spectral analyses of the RR interval and blood pressure in 20 patients with de novo PD without OH.Results:  Decreased cardiac MIBG uptake was found even in patients with PD without OH. Hemodynamic studies using the Valsalva maneuver revealed that patients with PD without OH had preserved baroreceptor reflex sensitivity in phase II and phase IV. Blood pressures normally responded in early and late phase II, but not in phase IV. Blood pressure recovery time was slightly reduced in patients with PD without OH when compared with the value in controls. The low frequency component of the RR interval and systolic blood pressure and the ratio of RR‐LF to RR‐HF in de novo PD without OH were significantly reduced when compared with the control values, whereas the high frequency component of the RR interval did not differ significantly.Conclusion:  These results show that latent cardiac and vasomotor sympathetic dysfunction but not parasympathetic dysfunction is already present in early stage de novo PD, even without orthostatic hypotension.
Distribution, clinical correlates and significance of axonal loss and demyelination in chronic inflammatory demyelinating polyneuropathy
Authors: Rajabally Y. A. , Narasimhan M. 
Published: June 2010

Background:  The distribution of axonal loss and demyelination has rarely been studied in chronic inflammatory demyelinating polyneuropathy (CIDP). Whether electrophysiological parameters may represent clinically relevant biomarkers of disease activity in the disorder remains uncertain. The purpose of this study was (i) to ascertain the distribution of electrophysiological motor abnormalities to optimize the diagnostic utility of nerve conduction studies and (ii) to establish electro‐clinical correlations in an attempt to find the potential parameters that could represent adequate biomarkers of disease activity and prognosis.Methods:  The clinical and electrophysiological motor features of 31 prospectively recruited patients with clinically stabilized CIDP were analysed.Results:  Axonal loss predominated in the lower limbs, but demyelination was more common in the upper limbs. About 50% of all demyelinating abnormalities were detected in asymptomatic regions. Presence of weakness correlated with abnormal compound muscle action potential (CMAP) and abnormal motor nerve conduction velocity (MNCV). Degree of weakness and functional scores only consistently correlated with CMAP amplitudes. CMAP abnormality correlated with abnormal MNCV, abnormal distal motor latency (DML) and presence of conduction block (CB). However, although CMAP amplitudes also correlated with MNCVs and DMLs in raw values, they did not relate to the degree of CB.Conclusion:  Electrodiagnosis of CIDP is optimized by extensive testing of upper limb nerves and of asymptomatic regions. Raw value CMAP amelioration and MNCV normalization may be adequate markers of clinical improvement in CIDP. Similarly, raw value MNCV and DML amelioration, as well as CB reversal may represent adequate prognostic markers.
Sources of information on adverse effects: a systematic review
Authors: Golder Su , Loke Yoon K. 
Published: June 2010

AbstractBackground: Systematic reviews can provide accurate and timely information on adverse effects. An essential part of the systematic review process is a thorough search of the literature. This often requires searching many different sources. However, it is unclear which sources are most effective at providing information on adverse effects.Objective: To identify and summarise studies that have evaluated sources of information on adverse effects.Methods: Studies were located by searching in 10 databases as well as by reference checking, hand searching, citation searching and contacting experts.Results: A total of 6218 citations were retrieved yielding 19 studies which met the inclusion criteria. The included studies tended to focus on the adverse effects of drug interventions and compare the relative value of different sources using the number of relevant references retrieved from searches of each source. However, few studies were conducted recently with a large sample of references.Conclusions: This review suggests thatembase, Derwent Drug File,medlineand industry submissions may potentially provide the greatest number of relevant references for information on adverse effects of drugs. However, a systematic evaluation of the current value of different sources of information for adverse effects is urgently required.
Relation between Helicobacter pylori infection and gastrointestinal symptoms and syndromes
Authors: Rosenstock S , Kay L , Rosenstock C , Andersen L P , Bonnevie O , Jørgensen T 
Published: June 2010

Background—Helicobacter pylori is a human pathogen that colonises the gastric mucosa and causes permanent gastric inflammation.Aims—To assess the symptoms of H pylori infection in an adult unselected population.Subjects—A random sample of 3589 adult Danes who were examined in 1982 and 1987 (n=2987).Methods—Abdominal symptoms within the preceding year were recorded at both attendances. Circulating IgG antibodies against H pylori in serum samples drawn in 1982 were measured by using in-house indirect enzyme linked immunosorbent assays (ELISA).Results—People with increased levels of IgG antibodies to H pylori were more likely than uninfected individuals to report heartburn (odds ratio (OR) = 1.26, 95% confidence interval (CI) 1.03–1.54) and abdominal pain characterised by daily length (OR = 1.33, 95% CI 0.92–1.91), nocturnal occurrence (OR = 1.62, 95% CI 1.19–2.19), spring aggravation (OR = 1.68, 95% CI 0.70–4.05), and no relation to meals (OR = 0.62, 95% CI 0.43–0.91) or stress (OR = 0.69, 95% CI 0.50–0.95). The inclusion of people with increased levels of IgG antibodies to H pylori, but without upper dyspepsia, at study entry significantly increased the likelihood of reporting upper dyspepsia at follow up (OR = 1.71, 95% CI 1.24–2.36). People with epigastric pain and increased levels of IgM antibodies to H pylori only indicative of acute H pylori infection were more likely to report nocturnal pain, heartburn, nausea, and vomiting.Conclusions—H pylori infection may precede the development of dyspepsia and is associated with a variety of gastrointestinal symptoms in people with no history of peptic ulcer disease.
Increased expression of transforming growth factor α precursors in acute experimental colitis in rats
Authors: Hoffmann P , Zeeh J M , Lakshmanan J , Wu V S , Procaccino F , Reinshagen M , McRoberts J A , Eysselein V E 
Published: June 2010

Background and aim—Epidermal growth factor (EGF) and transforming growth factor α (TGF-α), members of the EGF family of growth factors, protect rat gastric and colonic mucosa against injury. Having shown previously that exogenously applied EGF protects rat colonic mucosa against injury, the aim of the present study was to evaluate the endogenously expressed ligand mediating the protective effect of EGF/TGF-α in vivo.Methods—In an experimental model of trinitrobenzene sulphonic acid (TNBS)/ ethanol induced colitis in rats EGF and TGF-α expression was evaluated using a ribonuclease protection assay, northern blot analysis, western blot analysis, and immunohistochemistry.Results—TGF-α mRNA increased 3–4 times at 4–8 hours after induction of colitis and returned to control levels within 24 hours. TGF-α immunoreactive protein with a molecular size of about 28 kDa representing TGF-α precursors increased markedly after induction of colitis with a peak at 8–12 hours. No fully processed 5.6 kDa TGF-α protein was detected in normal or inflamed colon tissue. Only a weak signal for EGF mRNA expression was detected in the rat colon and no EGF protein was observed by immunohistochemistry or western blot analysis.Conclusions—TGF-α precursors are the main ligands for the EGF receptor in acute colitis. It is hypothesised that TGF-α precursors convey the biological activity of endogenous TGF-α peptides during mucosal defence and repair.
Peutz-Jeghers polyps, dysplasia, and K-ras codon 12 mutations
Authors: Entius M M , Westerman A M , Giardiello F M , van Velthuysen M-L F , Polak M M , Slebos R J C , Wilson J H P , Hamilton S R , Offerhaus G J A 
Published: June 2010

Background—Peutz-Jeghers syndrome (PJS) is a rare, autosomal dominant, polyposis syndrome, associated with an increased risk of gastrointestinal and extragastrointestinal malignancy. Occasionally dysplasia occurs in PJS polyps.Aims—In colorectal carcinomas, mutations in codon 12 of the K-ras oncogene are common and are found at similar frequency in precursor adenomas. Therefore, K-rascodon 12 point mutations in PJS polyps were evaluated.Materials and methods—Fifty two PJS polyps, including four with dysplasia, collected from 19 patients with PJS, were analysed for mutations in the K-ras codon 12 by a mutant enriched polymerase chain reaction procedure, followed by allele specific oligodeoxynucleotide hybridisation.Results—A K-ras codon 12 mutation was identified in one colonic polyp with dysplasia. The mutation was found in the non-neoplastic epithelial cells and not in the dysplastic component of the polyp.Conclusions—K-ras codon 12 point mutations are very rare in PJS polyps, by contrast with colorectal adenomas. The findings support previous evidence that there seems to be no intrinsic relation between K-ras codon 12 mutation and dysplasia.