ras Mutations and a cup of coffee: cause, confounder, effect modifier, or what else?

Epidemiologische Grundlagen nosokomialer Infektionen

Viele Faktoren tragen zu erhöhten nosokomialen Infektionsraten bei. Der Anteil alter Patienten mit chronischen Krankheiten und Immunsupprimierter steigt. Fortschritte in Diagnostik und Therapie resultieren immer häufiger in invasiven Eingriffen. Antibiotikaresistenzen und Folgen nosokomialer Infektionen erfordern daher eine verlässliche Epidemiologie. Konsequenzen nosokomialer Infektionen betreffen einerseits Patienten (Morbidität und Letalität), aber auch das Gesundheitswesen, dem zusätzliche, teilweise vermeidbare finanzielle Belastungen entstehen.

Pancreatic intraepithelial neoplasia and ductal adenocarcinoma induced by DMBA in mice: effects of alcohol and caffeine

PURPOSE

To evaluate the effects of alcohol and caffeine in a pancreatic carcinogenesis mouse model induced by 7,12-dimethylbenzantracene (DMBA), according to the PanIN classification system.

METHODS

120 male, Mus musculus, CF-1 mice were divided into four groups. Animals received either water or caffeine or alcohol or alcohol + caffeine in their drinking water. In all animals, 1 mg of DMBA was implanted into the head of the pancreas. After 30 days, euthanasia was performed; excised pancreata were then fixed in formalin, stained with hematoxylin-eosin and categorized as follows: normal ducts, reactive hyperplasia, PanIN-1A, PanIN-1B, PanIN-2, PanIN-3 or adenocarcinoma.

RESULTS

PanIN lesions were verified in all groups. Adenocarcinoma was detected in 15% of animals in the caffeine group, 16.6% in the water group, 23.8% in the alcohol + caffeine group and 52.9% in the alcohol group (P<0.05).

CONCLUSIONS

The experimental pancreatic carcinogenesis mouse model using DMBA effectively induces PanIN lesions and pancreatic adenocarcinoma. This study verified the association between alcohol use and pancreatic adenocarcinoma; caffeine did not present the same effect.

Food and nutrient intakes and K-ras mutations in exocrine pancreatic cancer

BACKGROUND

No studies have investigated the relation between K-ras mutations and dietary factors in exocrine pancreatic cancer (EPC), and fewer than 10 studies have done so in other neoplasms.

PATIENTS AND METHODS

Incident cases of EPC were prospectively identified, and interviewed face-to-face during hospital admission. Food and nutrient intakes were measured with a food frequency questionnaire. Logistic regression was used to compare EPC cases (n = 107) with and without K-ras mutations (case-case study).

RESULTS

K-ras mutations were more common among daily consumers of milk and other dairy products than among non-daily consumers: the odds ratio adjusted by total energy, age, sex, smoking, alcohol and coffee consumption (ORa) was 5.1 (95% CI 1.1 to 24.5, p = 0.040). For all dairy products, including butter, the ORa for the medium and upper tertiles of intake were 5.4 and 11.6, respectively (p for trend = 0.023). The ORa for regular coffee drinkers further adjusted by dairy consumption was 4.7 (95% CI 1.1 to 20.7, p = 0.043). K-ras mutated cases reported a lower intake of vitamin E (ORa = 0.2, p for trend = 0.036), polyunsaturated fats and omega 3 fatty acids (ORa = 0.2; p for trend <0.03).

CONCLUSIONS

Results support the hypothesis that in EPC exposure to specific dietary components or contaminants may influence the occurrence or persistence of K-ras mutations.

Epidemiologische Grundlagen

Eine Vielzahl an Faktoren tragen zu erhöhten nosokomialen Infektionsraten bei. Die Lebenserwartung und damit der Anteil alter Patienten mit z. T. chronischen Krankheiten steigen stetig an. Medizinische Fortschritte in Diagnostik und Therapie führen zu einer höheren Anzahl der dafür erforderlichen Eingriffe. Es werden immer häufiger immunsupprimierte Patienten (Infektiologie, Rheumatologie, Hämatologie/Onkologie, Transplantation von Organen usw.) behandelt. Das zunehmende Problem der Antibiotikaresistenz von Erregern und die Konsequenzen nosokomialer Infektionen erfordern eine verlässliche Epidemiologie auf diesem Gebiet. Konsequenzen betreffen einerseits Patienten, bei denen es zu einer erhöhten Morbidität und Letalität durch nosokomiale Infektionen kommt, aber andererseits auch das Gesundheitswesen, dem zusätzliche — vermeidbare? — finanzielle Belastungen entstehen.

Evidenzbasierte Empfehlungen, bei denen der jeweilige Einzelfall und die örtlichen Besonderheiten ebenfalls Berücksichtigung finden, sind Voraussetzung für eine sinnvolle und kosteneffektive Vorgehensweise zur Senkung der nosokomialen Infektionsrate. In vielen Studien sind Häufigkeiten und Folgen verschiedener nosokomialer Infektionsarten sowie Maßnahmen zu ihrer Prävention untersucht worden. Um die Qualität solcher Studien und die darauf basierenden Empfehlungen von Experten, die ja oftmals ebenfalls mit Kosten verbunden sind, kritisch beurteilen zu können, ist epidemiologisches Wissen unverzichtbar. Dies beinhaltet selbstverständlich auch die Kenntnis der jeweiligen Erreger solcher Infektionen sowie das Wissen um erregerspezifische Übertragungswege. Die Epidemiologie nosokomialer Infektionen ist daher die Grundlage ihrer eigenen Verbesserung.

»Es gibt nicht Kranke und Gesunde, sondern es gibt nur Untersuchte und nicht Untersuchte« (Johannes Rau, ehemaliger Bundespräsident).

Exploring environmental causes of altered ras effects: fragmentation plus integration?

Mutations in ras genes are the most common abnormality of oncogenes in human cancer and a major example of activation by point mutation. Experimental and epidemiological studies support the notion that Ki-ras activation and expression may be chemically related. We discuss the potential role of several environmental compounds in the induction or promotion of ras mutations in humans, with a focus on exocrine pancreatic cancer, the human tumor with the highest prevalence at diagnosis of Ki-ras mutations. Organochlorine compounds, organic solvents, and coffee compounds may play an indirect role in causing Ki-ras mutations, rather than as direct inducers of the mutations. Although for some organochlorine compounds the induction of point mutations in ras oncogenes cannot be excluded, it seems more likely that the effects of these compounds are mediated through nongenomic or indirectly genotoxic mechanisms of action. Organic solvents also may act via enzymatic induction of ras mutagens or by providing a proliferation advantage to ras-mutated cell clones. In exocrine pancreatic cancer, caffeine, other coffee compounds, or other factors with which coffee drinking is associated could modulate Ki-ras activation by interfering with DNA repair, cell-cycle checkpoints, and apoptosis. Asbestos, cigarette smoking, and some dietary factors also may be involved in the initiation or the promotion of Ki-ras mutations in lung and colon cancers. Further development of the mechanistic scenarios proposed here could contribute to a meaningful integration of biological, clinical, and environmental knowledge on the causes of altered ras effects.

Premalignant conditions of the pancreas

Premalignant conditions of the pancreas include benign tumours of the pancreas, intraepithelial neoplasia arising within pancreatic ducts, and tumours of the neuroendocrine cells of the pancreas. In addition, there is a variety of rare genetic conditions that predispose to pancreatic exocrine malignancies such as Peutz-Jeghers syndrome, hereditary non-polyposis colorectal cancer syndrome, familial pancreatitis, germline BRCA2 mutations, and pancreatic endocrine malignancies such as type 1 neurofibromatosis (von Recklinghausen's disease) and multiple endocrine neoplasia type 1. More controversial is the concept of chronic pancreatitis and diabetes mellitus as conditions that increase the risk of pancreatic cancer. However, there is no doubt that smoking is a potentiating factor for pancreatic cancer, especially in people who have familial/genetic risk factors. This review will include the recently proposed new nomenclature and classification system for intraepithelial neoplasia in the pancreatic ducts, an overview of the various familial syndromes that are associated with an increased risk of pancreatic tumours, the surveillance programmes that have been introduced to monitor such families, and methods for early diagnosis.

K-Ras mutations and benign pancreatic disease

This review addresses the history of the ras oncogene, the techniques used to detect molecular alterations in the ras oncogene, and the application of polymerase chain reaction (PCR)-based methods to determine point mutations in clinical samples of patients with pancreatic diseases, namely pancreatic carcinoma and chronic pancreatitis. The frequency of ras mutations in pancreatic carcinoma is high, ranging from 70 to almost 100%. The frequence of ras mutations in chronic pancreatitis, either in pancreatic tissue or pancreatic secretions, vary between 0 and 100%. This wide range in part may be owing to differences in sampling, DNA extraction, or PCR method. The meaning of a k-ras mutation is under debate. Taking into account the positivity of ductal hyperplasias in normal pancreas and ras mutations in normal appearing duct cells, this molecular finding may not mean anything. In contrast, ras mutations are associated with smoking, one acknowledged risk factor for pancreatic carcinoma. The need for large prospective cohort studies is emphasized.