A family of multiple endocrine neoplasia type 2A (MEN 2A) with Cys630Tyr RET germline mutation: report of a case

Since the majority of multiple endocrine neoplasia type 2A (MEN 2A) patients have missense mutations at codon 634 and those with the Cys630 RET genotype mutations are extremely rare, limited clinical information is available about this rare type. We report here three members of one Japanese MEN 2A family with the Cys630Tyr genotype. A 67-year-old woman presented a firm thyroid nodule, and preoperative examination revealed medullary thyroid carcinoma with primary hyperparthyoidism and no pheochromocytoma. At surgery, bilateral medullary thyroid carcinomas and parathyroid adenoma were found. No lymph node metastasis was identified. Computed tomography scans and laboratory examination of blood have shown no evidence of tumor recurrence and no abnormality of parathyroid function during the 4 years after surgery. A 40-year-old man, the proband's son, was shown to have the same RET mutation, underwent total thyroidectomy prophylactically, and only microscopic foci of medullary thyroid carcinoma were found. A 10-year-old boy, the proband's grandson also having the same RET mutation, showed normal basal serum calcitonin level and has been followed up conservatively. To our knowledge, 18 patients of 6 families with the Cys630 mutations have been reported so far. This is only the second reported case with primary hyperparathyroidism. RET 630 mutations might be associated with lower penetrance of primary hyperparthyoidism and pheochromocytoma.     

Regulation of anaphylactic responses by phosphatidylinositol phosphate kinase type I {alpha}

The membrane phospholipid phosphatidylinositol 4, 5-bisphosphate [PI(4,5)P(2)] is a critical signal transducer in eukaryotic cells. However, the physiological roles of the type I phosphatidylinositol phosphate kinases (PIPKIs) that synthesize PI(4,5)P(2) are largely unknown. Here, we show that the alpha isozyme of PIPKI (PIPKIalpha) negatively regulates mast cell functions and anaphylactic responses. In vitro, PIPKIalpha-deficient mast cells exhibited increased degranulation and cytokine production after Fcepsilon receptor-I cross-linking. In vivo, PIPKIalpha(-/-) mice displayed enhanced passive cutaneous and systemic anaphylaxis. Filamentous actin was diminished in PIPKIalpha(-/-) mast cells, and enhanced degranulation observed in the absence of PIPKIalpha was also seen in wild-type mast cells treated with latrunculin, a pharmacological inhibitor of actin polymerization. Moreover, the association of FcepsilonRI with lipid rafts and FcepsilonRI-mediated activation of signaling proteins was augmented in PIPKIalpha(-/-) mast cells. Thus, PIPKIalpha is a negative regulator of FcepsilonRI-mediated cellular responses and anaphylaxis, which functions by controlling the actin cytoskeleton and dynamics of FcepsilonRI signaling. Our results indicate that the different PIPKI isoforms might be functionally specialized.     

Insulin independence after living-donor distal pancreatectomy and islet allotransplantation

Rising demand for islet transplantation will lead to severe donor shortage in the near future, especially in countries where cadaveric organ donation is scarce. We undertook a successful transplantation of living-donor islets for unstable diabetes. The recipient was a 27-year-old woman who had had brittle, insulin-dependent diabetes mellitus for 12 years. The donor, who was a healthy 56-year-old woman and mother of the recipient, underwent a distal pancreatectomy. After isolation, 408 114 islet equivalents were transplanted immediately. The transplants functioned immediately and the recipient became insulin-independent 22 days after the operation. The donor had no complications and both women showed healthy glucose tolerance. Transplantation of living-donor islets from the distal pancreas can be sufficient to reverse brittle diabetes.     

Sec16B is involved in the endoplasmic reticulum export of the peroxisomal membrane biogenesis factor peroxin 16 (Pex16) in mammalian cells

Sec16 plays a key role in the formation of coat protein II vesicles, which mediate protein transport from the endoplasmic reticulum (ER) to the Golgi apparatus. Mammals have two Sec16 isoforms: Sec16A, which is a longer primary ortholog of yeast Sec16, and Sec16B, which is a shorter distant ortholog. Previous studies have shown that Sec16B, as well as Sec16A, defines ER exit sites, where coat protein II vesicles are formed in mammalian cells. Here, we reveal an unexpected role of Sec16B in the biogenesis of mammalian peroxisomes. When overexpressed, Sec16B was targeted to the entire ER, whereas Sec16A was mostly cytosolic. Concomitant with the overexpression of Sec16B, peroxisomal membrane biogenesis factors peroxin 3 (Pex3) and Pex16 were redistributed from peroxisomes to Sec16B-positive ER membranes. Knockdown of Sec16B but not Sec16A by RNAi affected the morphology of peroxisomes, inhibited the transport of Pex16 from the ER to peroxisomes, and suppressed expression of Pex3. These phenotypes were significantly reversed by the expression of RNAi-resistant Sec16B. Together, our results support the view that peroxisomes are formed, at least partly, from the ER and identify a factor responsible for this process.Most eukaryotic cells contain peroxisomes, which are single membrane-bound organelles that function in various metabolic pathways, including the β-oxidation of fatty acids, biosynthesis of plasmalogens and bile acids, and hydrogen peroxide metabolism (1). To perform this variety of functions, peroxisomes are highly dynamic; their number, size, and function change in response to cellular conditions. In addition, unlike mitochondria, peroxisomes can be formed through de novo synthesis as well as through the growth and division of preexisting peroxisomes (2, 3).Peroxisomal matrix proteins are synthesized on free ribosomes in the cytosol and posttranslationally imported to peroxisomes (4). This import pathway includes the recognition of two distinct peroxisomal targeting signals (PTS1 and PTS2) by peroxin 5 (Pex5) and Pex7, respectively, followed by translocation across the membrane through the import machinery, including Pex14 and Really Interesting New Gene peroxins (5, 6). The import pathway for peroxisomal membrane proteins (PMPs), on the other hand, is believed to be independent of that used by matrix proteins. Genetic phenotype complementation analysis of yeast and mammalian mutants devoid of peroxisome membranes revealed that Pex3, Pex16, and Pex19 are essential for PMP import (references in ref. 7). Pex3 is a PMP import receptor (8), and Pex19 is a chaperone and import receptor for most PMPs (9). Pex16 appears to function as a Pex3-Pex19 receptor in mammals (7) and as a negative regulator of peroxisome fission in yeast Yarrowia lipolytica (10) but is absent in Saccharomyces cerevisiae (11).Although compelling evidence suggests that PMPs are transported directly from the cytosol to peroxisomes (7–9, 12), recent work has suggested that some PMPs, including the PMP import receptors Pex3 and Pex16, seem to be, at least partly, transported from the endoplasmic reticulum (ER) en route to peroxisomes (13). In addition, several lines of evidence suggest that the ER participates in the de novo formation of peroxisomes (13–20). A very recent study involving a yeast cell-free system revealed that ER-peroxisome carriers are formed in a Pex19-dependent manner (21).In this report, we show that Sec16B plays an important role in the transport of Pex16 from the ER to peroxisomes in mammalian cells. Sec16 was first characterized in yeast S. cerevisiae as a 240-kDa peripheral membrane protein that interacts with coat protein II (COPII) coat components and facilitates their assembly and vesicle budding (22–25). In yeast Pichia pastoris, Sec16 defines ER exit sites (ERESs) (26), special domains where COPII-coated vesicles are formed (27). There are two mammalian orthologs, Sec16A (250 kDa) and Sec16B (117 kDa) (also referred to as Sec16L and Sec16S, respectively) (28–30). Sec16A, which is localized in cup-like structures in ERESs (31), appears to be the primary Sec16 ortholog because its molecular mass is similar to that of Sec16 in yeast (22) and Drosophila (32). Sec16B, which appears to be conserved in vertebrates, is also localized in ERESs, but its function has not been fully examined in the context of membrane trafficking. Our results suggest that Sec16B may participate in the formation of new peroxisomes derived from the ER.     

Successful chemotherapy of carcinomatosis of the bone marrow with disseminated intravascular coagulation from a rectal carcinoma found by eosinophilia

A 71-year-old man with eosinophilia was given a diagnosis of poorly differentiated adenocarcinoma of the rectum. Further examination showed that it had invaded the bone marrow. He had disseminated intravascular coagulation (DIC) from disseminated carcinomatosis of the bone marrow after colostomy. Chemotherapy (mFOLFOX6) was successful and his eosinophil count, DIC score and tumor markers normalized. We were able to continue chemotherapy after 5 months from the outbreak of disseminated carcinomatosis of the bone marrow. It is said that disseminated carcinomatosis of the bone marrow has a poor prognosis, but we were able to obtain a good response in this case by chemotherapy.     

<Emphasis Type="Italic">PIK3CA</Emphasis> alterations in primary (de novo) and secondary glioblastomas

We assessed alterations in the EGFR/PTEN/PI3K pathway in 107 primary (de novo) glioblastomas and 32 secondary glioblastomas that progressed from low-grade or anaplastic astrocytomas. SSCP followed by DNA sequencing in exons 9 and 20 of the PIK3CA gene revealed missense mutations in 5/107 (5%) primary and 1/32 (3%) secondary glioblastomas. Quantitative real-time PCR showed PIK3CA amplification (>3 copy numbers) in 14/107 (13%) primary and 3/32 (9%) secondary glioblastomas. Only one glioblastoma showed both PIK3CA mutation and amplification. Taken together with previously published data on EGFR amplification and PTEN mutations, at least one alteration in the EGFR, PTEN, or PIK3CA genes was detected in 63% of primary glioblastomas, which was significantly more frequent than in secondary glioblastomas (31%; P < 0.001). Furthermore, this signaling pathway was altered by either PTEN mutations or PIK3CA amplification in 10 of 12 (83%) malignant glioma cell lines analyzed. These results suggest that the EGFR/PTEN/PI3K pathway is frequently altered in glioblastomas and is a promising target for therapy, in particular for primary glioblastomas.     

Lipid metabolism after operation for esophageal cancer

In order to clarify the abnormal lipid metabolism after resection of esophageal cancer, we measured serum cholesterol, HDL cholesterol, triglyceride phospholipid, free fatty acid, lipoprotein and apoprotein in 38 patients with esophageal cancer before and up to 4 weeks after operation. Patients were divided into three groups; group A consisted of 26 patients whose postoperative course was uneventful, group B, 12 patients who suffered from post-operative complications and group C, 15 control patients who underwent gastrectomy for cancer of the stomach. The conclusions were; 1) After operation, remarkable decrease was observed in many lipids and proteins which were synthesized mainly in the liver. This was more prominent in groups A and B than in group C. There was no difference between group A and B up to 2 weeks, however, after that recovery was slow in group B. 2) This decrease in serum lipids and proteins may be explained by the postoperative liver dysfunction which mimics acute hepatitis, and by abnormal increase in their consumption. 3) In group B, preoperative serum cholesterol, HDL cholesterol and albumin had been significantly lower than those in group A, and cholinesterase, apoAI and apoAII had also tended to be lower.     

Effect of CNTF on ischaemic cell damage in rat hippocampus

Summary The neuroprotective effect of neurotrophic factors has been demonstrated in experimental cerebral ischaemia recently. These include nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), insulin-like growth factor-1 (IGF-1), and basic fibroblast growth factor (basic FGF). The neuroprotective effect of ciliary neurotrophic factor (CNTF), however, has not been studied so far.We have examined the neuroprotective effect of recombinant rat CNTF in a rat forebrain ischaemia model. A continuous infusion of CNTF was started 1 week before the induction of ischaemia and continued until 1 week after the ischaemia. Reversible forebrain ischaemia was induced by 7 minutes of bilateral carotid occlusion with hypotension. Neuronal cell death in the hippocampal CA1 sector was evaluated 1 week after the ischaemia. For the control group artificial CSF (cerebrospinal fluid) was infused instead of CNTF.Per cent neuronal cell death was 83.4 ± 5.9% (mean ± SEM, n=5) in the control group, and 71.1 ± 10.0% (mean ± SEM, n=5) in the CNTF group. Although percentage of neuronal cell death was lower in the CNTF group, the difference was not statistically significant.This result suggests that the protective effect of CNTF in the rat forebrain ischaemia model may be limited compared with other neurotrophic factors. It is considered that the number of neurons protected by CNTF may be small.