Metabolism of Very Long-Chain Fatty Acids: Genes and Pathophysiology

Fatty acids (FAs) are highly diverse in terms of carbon (C) chain-length and number of double bonds. FAs with C>20 are called very long-chain fatty acids (VLCFAs). VLCFAs are found not only as constituents of cellular lipids such as sphingolipids and glycerophospholipids but also as precursors of lipid mediators. Our understanding on the function of VLCFAs is growing in parallel with the identification of enzymes involved in VLCFA synthesis or degradation. A variety of inherited diseases, such as ichthyosis, macular degeneration, myopathy, mental retardation, and demyelination, are caused by mutations in the genes encoding VLCFA metabolizing enzymes. In this review, we describe mammalian VLCFAs by highlighting their tissue distribution and metabolic pathways, and we discuss responsible genes and enzymes with reference to their roles in pathophysiology.     

Early colon cancers detected by FDG-pet: a report of two cases with immunohistochemical investigation

Increased glucose uptake is one of the metabolic characteristics of tumor cells. 18F-fluorodeoxyglucose (FDG)-positron emission tomography (FDG-PET), a technique that is used widely to study this altered glucose metabolism in tumors, allows the detection of various types of malignancy. We present herein two cases of early colon cancers detected incidentally by FDG-PET. The technique was used as part of the screening examinations for preoperative staging, and for postoperative follow-up. In both cases, the lesions were removed by colonoscopic polypectomy, with no complications. Moreover, we confirmed the existence of altered glucose metabolism in the resected specimen by immunohistochemical staining using an antibody raised against Glut1. Immunohistochemically, Glut1 was expressed in vitro in both of the lesions, supporting the positive FDG-PET result obtained in vivo. To our knowledge, this is the first report to describe in vitro Glut1 expression and in vivo tumor detection using FDG-PET in colorectal carcinoma.     

Comparison of the clinical courses of the opticospinal and conventional forms of multiple sclerosis in Japan

We evaluated the clinical courses of 216 patients with multiple sclerosis (MS) diagnosed according to the recommended diagnostic criteria of McDonald et al (10). Sixty-five patients clinically displaying selective involvement of the optic nerves and spinal cord were classified as opticospinal MS (OS-MS), while the other 151 showing disseminated involvement of the central nervous system were classified as conventional MS (C-MS). The disease duration did not differ significantly between the two subtypes (11.2 years vs. 11.5 years). In addition to a higher age of onset, female preponderance and higher Kurtzke's expanded disability status scale (EDSS) scores, the OS-MS patients showed a markedly lower frequency of secondary progressive MS than the C-MS patients (4.6% vs. 29.1%, p=0.0001). The EDSS scores of the C-MS patients were significantly correlated with the disease duration, while those of the OS-MS patients were not. Among the C-MS patients, the frequency of secondary progressive MS was significantly more common in patients with a disease duration of more than 10 years than in those with a shorter duration. These results suggest that the irreversible disability in OS-MS is determined by relapses, rather than by chronic progression, whereas C-MS has a similar clinical course to MS in Westerners.