Primary mediastinal tumors. Part 1: tumors of the anterior mediastinum

Primary anterior mediastinal neoplasms comprise a diverse group of tumors and account for 50% of all mediastinal masses. Thymomas are most common and can be locally invasive and associated with parathymic syndromes. Thymic carcinomas and thymic carcinoids are rare malignancies with a propensity for local invasion and distant metastases. Thymolipomas are benign thymic tumors. The mediastinal germ cell tumors are a heterogeneous group of benign and malignant neoplasms. Mediastinal lymphangiomas are rare tumors and predominantly occur in young children. In contrast, mediastinal goiters are relatively common in adults. Mediastinal parathyroid adenomas are an uncommon cause of persistent hyperparathyroidism and rarely cause a discernible mass. The clinical, radiologic, and therapeutic aspects of the most common masses are reviewed.

NIT-1, a pancreatic beta-cell line established from a transgenic NOD/Lt mouse

NOD/Lt mice harboring a hybrid rat insulin-promoter/SV40 large T-antigen gene spontaneously develop beta-cell adenomas. NIT-1 is a pancreatic beta-cell line established from one of these transgenic mice. Immunocytochemical staining of passage 18 cells showed most contained insulin, with less than 5% containing glucagon, and none containing pancreatic polypeptide or somatostatin. Glucagon content radioimmunoassayed in cell extracts was only 0.27% of the insulin content. Two-hour insulin secretion at 16.5 mM glucose was 638 ng/10(6) cells (41% of intracellular content) compared to only 1.3 ng glucagon (32% of intracellular content). Stimulated insulin secretion was consistently observed in response to 11 and 16.5 mM glucose between passages 11 and 19. At passage 19, both theophylline and tolbutamide stimulated insulin secretion at 5.5 mM glucose. Northern-blot analysis confirmed high levels of insulin mRNA but only trace glucagon mRNA and undetectable somatostatin mRNA. Interferon-gamma (IFN-gamma)-induced MHC class I RNA expression was correlated with markedly increased antigen expression at the cell surface. Similarly, a MHC-linked "occult" class I-like antigen detected by Cr release assay only after exposure of standard NOD/Lt islet cells to IFN-gamma was strongly induced by IFN-gamma in NIT-1 cells. Cell surface MHC class II antigen was not constitutively expressed on NIT-1 cells and could not be detected after IFN-gamma incubation, despite demonstration of IFN-gamma-induced Aa, Ab, and Li invariant-chain RNA transcripts. Similarly IFN-gamma induction of intercellular adhesion molecule 1 (Icam-1) transcripts was not accompanied by demonstrable cell surface expression of ICAM-1 antigen.(ABSTRACT TRUNCATED AT 250 WORDS)

Physical activity and colorectal cancer

Physical activity has been shown to reduce risk of colon cancer. Some studies have shown site-specific associations while others have not. The inverse association between physical activity and colon cancer is consistent although only 7 of 13 studies that have collected both colon and rectal cancer data in the same manner report reduced risk for rectal cancer; four of these studies detected statistically significant inverse associations. The frequency, duration and intensity of activity are important components of a public health message to reduce risk of colon cancer through performance of physical activity. However, difficulties in estimating the exact amount of activity needed and frequency and intensity of activity result in only crude estimates of dose needed for a protective effect. Much of the literature suggest that more intense activity is needed to reduce colon cancer risk and that somewhere between 3.5 and 4 hours of vigorous activity per week may be needed to optimise protection. Several biological mechanisms have been proposed to explain the association between physical activity and colon cancer; many of these mechanisms also support the observation that intense activities are most protective. Biological mechanisms include: physical activity increasing gut motility; enhancing the immune system; decreasing insulin and insulin-like growth factor levels; decreasing obesity; enhancing free radical scavenger systems; and influencing prostaglandin levels. The evidence taken together provides strong support for lack of physical activity being causally related to colon cancer. It has been estimated that 12-14% of colon cancer could be attributed to lack of frequent involvement in vigorous physical activity.

Hedgehog signalling in colorectal tumour cells: induction of apoptosis with cyclopamine treatment

Hedgehog (Hh) signalling controls many aspects of development. It also regulates cell growth and differentiation in adult tissues and is activated in a number of human malignancies. Hh and Wnt signalling frequently act together in controlling cell growth and tissue morphogenesis. Despite the fact that the majority of colorectal tumours have a constitutively activated canonical Wnt pathway, few previous studies have investigated the expression of Hh signalling components in colorectal tumours. We describe here epithelial cell lines derived from both nonmalignant colorectal adenomas and colorectal adenocarcinomas that express both Sonic and Indian Hh. Interestingly, these cells also express the Hh receptor Patched and the downstream signalling components Smoothened and Gli1, suggesting autocrine Hh signalling in these cells. To test whether autocrine Hh signalling contributes to cell survival, we treated colorectal tumour cells with cyclopamine, a known inhibitor of Hh signalling. Cyclopamine treatment induced apoptosis in both adenoma- and carcinoma-derived cell lines, which could be partially rescued by further stimulation of Hh signalling. These data suggest that autocrine Hh signalling can increase aberrant cell survival in colorectal tumour cells and may be a novel target for colon cancer therapy using drugs such as cyclopamine.

THE ADRENOCORTICAL RESPONSE TO INSULIN-INDUCED HYPOGLYCAEMIA

The adrenocortical response to stress as shown by an increase of the plasma cortisol concentration during insulin-induced hypoglycaemia has been studied. The response was found to depend upon the degree and duration of the hypoglycaemia and upon the integrity of the entire hypothalamo-pituitary-adrenal axis. Thus, there was no response in subjects in whom the blood sugar did not fall below 40 mg./100 ml., nor in patients with severe hypothalamic or pituitary disorders.

The test was quick and simple to perform and did not require admission to hospital; it would seem to be of considerable value in the investigation of patients with suspected endocrine disease.

Identification of microbial markers across populations in early detection of colorectal cancer

Associations between gut microbiota and colorectal cancer (CRC) have been widely investigated. However, the replicable markers for early-stage adenoma diagnosis across multiple populations remain elusive. Here, we perform an integrated analysis on 1056 public fecal samples, to identify adenoma-associated microbial markers for early detection of CRC. After adjusting for potential confounders, Random Forest classifiers are constructed with 11 markers to discriminate adenoma from control (area under the ROC curve (AUC) = 0.80), and 26 markers to discriminate adenoma from CRC (AUC = 0.89), respectively. Moreover, we validate the classifiers in two independent cohorts achieving AUCs of 0.78 and 0.84, respectively. Functional analysis reveals that the altered microbiome is characterized with increased ADP-L-glycero-beta-D-manno-heptose biosynthesis in adenoma and elevated menaquinone-10 biosynthesis in CRC. These findings are validated in a newly-collected cohort of 43 samples using quantitative real-time PCR. This work proves the validity of adenoma-specific markers across multi-populations, which would contribute to the early diagnosis and treatment of CRC.

Artificial Intelligence in Colorectal Cancer Screening, Diagnosis and Treatment. A New Era

The development of artificial intelligence (AI) algorithms has permeated the medical field with great success. The widespread use of AI technology in diagnosing and treating several types of cancer, especially colorectal cancer (CRC), is now attracting substantial attention. CRC, which represents the third most commonly diagnosed malignancy in both men and women, is considered a leading cause of cancer-related deaths globally. Our review herein aims to provide in-depth knowledge and analysis of the AI applications in CRC screening, diagnosis, and treatment based on current literature. We also explore the role of recent advances in AI systems regarding medical diagnosis and therapy, with several promising results. CRC is a highly preventable disease, and AI-assisted techniques in routine screening represent a pivotal step in declining incidence rates of this malignancy. So far, computer-aided detection and characterization systems have been developed to increase the detection rate of adenomas. Furthermore, CRC treatment enters a new era with robotic surgery and novel computer-assisted drug delivery techniques. At the same time, healthcare is rapidly moving toward precision or personalized medicine. Machine learning models have the potential to contribute to individual-based cancer care and transform the future of medicine.

Dietary fibre and colorectal cancer: A model for environment - gene interactions

As environmental factors are clearly associated with risk for colorectal cancer, we set out to model how dietary fibre, or the effects of its ingestion, might impact upon the complex events that characterise colorectal oncogenesis. The diverse nature of dietary fibre and its resultant fate in the gut is outlined. The evidence indicates that different types of fibre create different conditions in different regions of the gut. This is reflected in different effects on oncogenesis especially in animal models. Data from animal models show that insoluble fibre is protective. Evidence from human studies are not consistent, especially considering the interventional studies. However, all such studies have been dependent on biomarkers short of cancer formation, for measurement of an effect. The biological and molecular events characteristic of colorectal oncogenesis are reviewed in an effort to identify how fibre ingestion might regulate oncogenesis. While several mechanisms might account for protection, the results of fermentation and especially butyrate production provide examples of how genomic instability might be controlled. Activation of apoptosis and cell cycle arrest seem likely to be mechanisms that would enable correction of genomic events that drive oncogenesis. Butyrate itself can regulate gene expression by both epigenetic and direct effects.