Quantitative analysis of p16 methylation in Barrett's carcinogenesis

p16 hypermethylation in Barrett's carcinogenesis has been evaluated in studies which did not take into account sample heterogeneity and yielded qualitative (methylated/unmethylated) instead of accurate quantitative (percentage of CpG methylation) data. We aimed to measure the degree of p16 methylation in pure samples representing all the steps of Barrett's tumorogenesis and to evaluate the influence of sample heterogeneity in methylation analysis.

METHODS

77 paraffin-embedded human esophageal samples were analyzed. Histological grading was established by two pathologists in: negative for dysplasia, indefinite for dysplasia, low-grade dysplasia, high-grade dysplasia and adenocarcinoma. Areas of interest were selected by laser-capture microdissection. p16 methylation was quantified by pyrosequencing. An adjacent section of the whole sample was also analyzed to compare methylation data.

RESULTS

After microdissection, we obtained 15 samples of squamous epithelium, 36 non-dysplastic Barrett's esophagus, 3 indefinite for dysplasia, 24 low-grade dysplasia, 4 high-grade dysplasia and 12 adenocarcinoma. Squamous epithelium showed the lowest methylation rates: 6% (IQR 5-11) vs. 11%(7-39.50) in negative/indefinite for dysplasia, p<0.01; 10.60%(6-24) in low-grade dysplasia, p<0.05; and 44.50%(9-66.75) in high-grade dysplasia/adenocarcinoma, p<0.01. This latter group also exhibited higher methylation rates than Barrett's epithelium with and without low-grade dysplasia (p<0.05). p16 methylation rates of microdissected and non-microdissected samples did not correlate unless the considered histological alteration comprised >71% of the sample.

CONCLUSIONS

p16 methylation is an early event in Barrett's carcinogenesis which increases with the severity of histological alteration. p16 methylation rates are profoundly influenced by sample heterogeneity, so selection of samples is crucial in order to detect differences.

Bedeutung einer eingeschränkten Gelenkbeweglichkeit für den Blutabstrom aus gesunden Beinvenen

An zehn venengesunden Probanden (5 Männern und 5 Frauen; Durchschnitts-alter: 25,5 ± 3 Jahre) wurde die Bedeutung der Beweglichkeit im Sprung- und Kniegelenk für den Blutrücktransport aus den Beinvenen beim Gehen phlebodynamometrisch untersucht. Die Probanden gingen auf einem Laufbandergometer (Geschwindigkeit: 1,5 km/h; keine Steigung; Gehzeit: 1 Minute) zunächst ohne Bewegungseinschränkung (Versuch I), dann mit Bewegungseinschränkung im Kniegelenk (Versuch II) und schließlich mit Bewegungseinschränkung im oberen Sprunggelenk (Versuch III). Primäre Zielvariable war der maximale venöse Druckabfall (ΔPmax) unter Belastung, sekundäre Zielvariablen die venöse Druckausgleichszeit (T0) bzw. die halbmaximale Druckausgleichszeit (Tmax1/2) nach Belastung. Der maximale Druckabfall im Beinvenensystem wurde durch die Aufhebung der Beweglichkeit im Knie- (p = 0,0323) bzw. im oberen Sprung-gelenk (p = 0,0051) signifikant reduziert. Die Verminderung von ΔPmax durch die Bewegungseinschränkung betrug für das Kniegelenk 12,0% und für das obere Sprunggelenk 21,5% (p = 0,0469). Demgegenüber wurden die venösen Auffüllzeiten (T0 und Tmax1/2) durch die Bewegungseinschränkung nicht beeinflußt (p >0,05; jeweils Vorzeichen-Rang-Test nach Wilcoxon). Diese Ergebnisse zeigen, daß Bewegungseinschränkungen im Knie- und insbesondere im oberen Sprunggelenk selbst bei venengesunden Probanden zu einer ambulatorischen venösen Hypertonie führen. Da diese ein gleichzeitig bestehendes Venenleiden aggravieren oder für sich selbst den venösen Blutabtransport stören können, sollten zur Gesamtbeurteilung der funktionellen Auswirkungen von Beinvenenerkrankungen stets die Gelenkfunktionen mitberücksichtigt werden. Dies gilt für die klinische Praxis ebenso wie für gutachterliche Fragestellungen.

Prostaglandin EP2 receptor expression is increased in Barrett's oesophagus and oesophageal adenocarcinoma

BACKGROUND

Accumulating evidence suggests that cyclooxygenase-2 (COX-2)-derived prostaglandin E2 (PGE2) is involved in oesophageal adenocarcinogenesis. PGE2 exerts its biological action by binding to specific receptors (EP1, EP2, EP3 and EP4).

AIM

To investigate which PGE2 receptor subtypes regulate PGE2 signals in the oesophageal adenocarcinoma sequence.

METHODS

Expression was determined in oesophageal biopsies from 85 patients with oesophagitis, Barrett's metaplasia, intraepithelial neoplasia, oesophageal adenocarcinoma and normal oesophagus. Levels of mRNA and protein expression were determined by quantitative PCR, immunohistochemistry and western-blot. Expression of EP receptors was also determined in response to acid and bile exposure in the Barrett's adenocarcinoma cell line OE33.

RESULTS

All four EP receptors subtypes were expressed in human oesophageal tissues. COX-2 and, especially, EP2 were increased in the Barrett's metaplasia-intraepithelial neoplasia-adenocarcinoma sequence. Expression of the EP4 receptor protein was increased in oesophageal adenocarcinoma. In contrast, expression levels of COX-1 and EP3 receptor were decreased along the sequence. No differences in EP1 expression were found. Treatment with the bile acid deoxycholate increased COX-2, EP1, EP2 and EP4 expression in OE33 cells.

CONCLUSIONS

Our data suggest that in addition to COX-2, EP2 and EP4 receptors could be a selective target in the prevention and/or treatment of the Barrett's-associated adenocarcinoma.

TGFB1 gene polymorphisms: their relevance in the susceptibility to Helicobacter pylori-related diseases

Recent studies have revealed elevated expression of transforming growth factor beta1 (TGF-beta1) in gastric mucosa of patients with gastric cancer (GC) and those undergoing ulcer repair. As production of TGF-beta1 is genetically regulated, we aimed to assess whether functional polymorphisms of the TGFB1 gene are involved in susceptibility to and clinical characteristics of Helicobacter pylori-related diseases. DNA from 142 unrelated Spanish patients with GC, 200 with peptic ulcer and 342 healthy controls was typed for the MspA1I T+869C, and the Sau96I G+915C polymorphisms of the TGFB1 gene using polymerase chain reaction and RFLP analysis. H. pylori infection and CagA/VacA antibody status were determined by Western blot in patients and controls. H. pylori infection (odds ratio (OR): 11.44; 95% confidence interval (CI): 4.45-29.42; P<0.001) and non-steroidal anti-inflammatory drugs (OR: 5.07; 95% CI: 2.53-10.16; P<0.001) were identified as independent risks factors for duodenal ulcer (DU), whereas the TGFB1+869(*)C/C genotype was associated with reduced risk of developing the disease (OR: 0.32; 95% CI=0.15-0.68; P=0.003). Our results show that the TGFB1 T+869C gene polymorphism is involved in the susceptibility to DU and provide further evidence that host genetic factors play a key role in the pathogenesis of H. pylori-related diseases.

Venous pressure dynamics of the healthy human leg. Role of muscle activity, joint mobility and anthropometric factors

The delicate interplay between the muscle-joint unit and intact venous valves is mandatory for normal venous blood return from the human leg. We have investigated the potential role of (1) muscle activity and joint mobility, and (2) anthropometric factors for peripheral venous pressure physiology. 20 healthy young subjects (10 males, 10 females; mean age: 25.6 +/- 3.1 years) underwent direct venous blood pressure measurements during walking on a treadmill in 12 experimental conditions (duration, 1 min each): these resulted from a combination of two different walking velocities, two different degrees of ascent, and three different walking conditions. Anthropometric parameters (e.g., body height, weight and calf circumference) were also measured in all subjects. Outcome measures were the pressures (mm Hg) during quiet standing (resting pressure, P(0)), the maximal activity-induced pressure reduction (Delta P(max)), i.e., the difference between the resting pressure (P(0)) and minimal pressure during exercise (P(min)), the times (s) to minimal pressure during exercise (T(Pmin)) and to half-maximal recovery of P(0) after exercise (T(max1/2)). We found that the maximal venous pressure reduction (Delta P(max)) during walking increased at the higher walking speed and decreased with restricted joint mobility (p = 0.0001). Taller and heavier subjects, or subjects with a greater calf circumference had higher P(0) (p = 0.0001), showed greater Delta P(max) (p < 0.010), and took longer to achieve minimal pressure during exercise (T(Pmin); p < 0.010) than their corresponding counterparts. Females had lower levels of P(0) (p = 0.0001), but not of Delta P(max), and shorter T(Pmin) (p = 0.0076) than males. These gender effects largely result from differences in body height, weight, and calf circumference (p = 0.0001 for the appropriate ANOVA interaction terms). We conclude that during walking, a higher degree of muscle activity and a greater muscle mass enhance venous emptying of the healthy human leg. Conversely, impairments of joint mobility reduce the efficacy of the muscle-vein pump. Moreover, body height and weight significantly influence venous pressure physiology under both resting and activity-related conditions. These anthropometric factors also largely explain sex differences in peripheral venous hemodynamics.

A new BRCA1 mutation in a Filipino woman with a family history of breast and ovarian cancer

Mutation of the BRCA1 gene in well-defined breast cancer families has been associated with an 87% lifetime risk for breast cancer and a 44% risk for ovarian cancer. Recent data indicate that the risk associated with these mutations is considerably lower, although still far greater than the risk for disease in the rest of the population. Approximately 81% of the mutations that have been identified have been frameshift (71%) or nonsense (10%) mutations, and either may result in a truncated protein. The protein truncation test (PTT) is often used to screen patients at high risk, because sequencing of this large (100 kb) gene with its 22 coding exons is an arduous task. The PTT was used to analyze genomic DNA and RNA from the peripheral blood of a 31-year-old Filipino woman with a poorly differentiated, stage 2A breast carcinoma and a family history of breast-ovarian cancer. PTT identified the wild-type protein fragment and an additional truncated protein fragment in the patient's sample. Subsequent direct sequencing of the appropriate coding region revealed a point mutation in exon 11 at nucleotide 2178, resulting in a C > T transition that caused a termination (stop codon) in amino acid 687. To our knowledge, this is the first report of mutation of the BRCA1 gene in a Filipino family, and this in-frame stop-codon mutation has not been reported previously.

[Pulmo cardialis: effect of inhaled bronchodilators on airway resistance of acute left ventricular dysfunction]

Disturbance of left ventricular function leads to an impairment of ventilation: airway resistance increases, while pulmonary compliance is reduced. We therefore studied the effect of inhalable bronchodilators (Fenoterol, Ipratropium bromide) on oscillatory airway resistance in 16 patients with an acute left heart failure. The results show that the resistance can be significantly reduced to normal values by the bronchodilators. Fenoterol has the greatest spasmolytic potency, but Ipratropium bromide is also effective. Recompensation of left heart function alone does not lead to comparable acute effects on airway resistance. The possibility of immediate improvement of ventilation through the use of inhalable bronchodilators should therefore be considered in the treatment of acute left heart failure.