Clinical and genetic analysis of 18 pancreatic carcinoma/melanoma‐prone families

Bartsch DK, Langer P, Habbe N, Matthäi E, Chaloupka B, Sina M, Hahn SA, Slater EP. Clinical and genetic analysis of 18 pancreatic carcinoma/melanoma‐prone families. Families with both melanoma and pancreatic cancer are extremely rare and some are affected with the autosomal dominant inherited familial atypical multiple mole melanoma‐pancreatic cancer (FAMMM‐PC) syndrome. The phenotypic and genotypic expressions of such pancreatic cancer–melanoma prone families are not well defined. The National Case Collection of Familial Pancreatic Cancer of the Deutsche Krebshilfe includes 110 pancreatic cancer families, 18 of which (16%) show an association of pancreatic cancer and melanoma. These 18 families were analysed regarding their phenotype and the prevalence of germline mutations in the candidate genes CDKN2A, BRCA2, CHEK2, NOD2, ARL11 and Palladin (PALLD). There were two types of families: five families with the FAMMM‐PC phenotype and 13 PC/melanoma families without the multiple mole phenotypes (PCMS). The prevalences of PC and melanoma in the two types of families were similar. The prevalence of other tumour types, especially breast carcinoma, was higher (11%) in PCMS‐ than in FAMMM‐PC families (2.4%, p = 0.02). CDKN2A mutations were identified in 2 of 18 (11%) PCMS families. A cosegregating BRCA2 mutation was detected in one PCMS family without breast cancer. None of the reported germline mutations in the NOD2, Palladin, ARL11 or CHEK2 genes were detected in either type of family. In conclusion, families with an accumulation of PC and melanoma show a large variety of phenotypic expression, which is not always consistent with the FAMMM‐PC phenotype. More PC/melanoma‐prone families need to be analysed to clarify whether such families represent variations of the FAMMM‐PC syndrome or two distinct hereditary cancer syndromes.     

PALB2 mutations in European familial pancreatic cancer families

Slater EP, Langer P, Niemczyk E, Strauch K, Butler J, Habbe N, Neoptolemos JP, Greenhalf W, Bartsch DK. PALB2 mutations in European pancreatic cancer families. Recently, PALB2 was reported to be a new pancreatic cancer susceptibility gene as determined by exomic sequencing, as truncating PALB2 mutations were identified in 3 of 96 American patients with familial pancreatic cancer (FPC). Representing the European Registry of Hereditary Pancreatitis and Familial Pancreatic Cancer (EUROPAC) and the German National Case Collection for Familial Pancreatic Cancer (FaPaCa), we evaluated whether truncating mutations could also be detected in European FPC families. We have directly sequenced the 13 exons of the PALB2 gene in affected index patients of 81 FPC families. An index patient was defined as the first medically identified patient, stimulating investigation of other members of the family to discover a possible genetic factor. None of these patients carried a BRCA2 mutation. We identified three (3.7%) truncating PALB2 mutations, each producing different stop codons: R414X, 508‐9delAG and 3116delA. Interestingly, each of these three families also had a history of breast cancer. Therefore, PALB2 mutations might be causative for FPC in a small subset of European families, especially in those with an additional occurrence of breast cancer.     

Effects of dose and dosing schedule of inhaled budesonide on bone turnover

To assess whether the use of larger than usual doses of inhaled steroid to treat severe asthma may adversely affect bone turnover and whether such an effect may be mitigated by altering the dose schedule, we investigated the effects of budesonide (BUD) on serum osteocalcin and the urinary output of hydroxyproline and calcium. Healthy adults were administered 1.2 or 2.4 mg of BUD per day (N = 40) or placebo (N = 8) in a crossover, double-blind comparison of morning versus diurnal dosing schedules for 1 month each. Both BUD doses reduced the 24-hour urinary free-cortisol output (p less than 0.001) and serum osteocalcin (p less than 0.001). The larger dose reduced the morning serum cortisol levels (p = 0.002). Neither dose increased the 8 AM urinary calcium or hydroxyproline output. Osteocalcin and plasma cortisol levels were higher on morning than on diurnal dosing (p = 0.01). The 24-hour urinary free-cortisol output was the same with either schedule (p = 0.96). Additional study is required to assess the clinical importance of the inhibitory effect of BUD on bone formation, as evidenced by the reduction in osteocalcin levels. Of concern is the possibility of serious bone complications resulting from the long-term use of inhaled steroid, particularly in growing children or patients in whom other risk factors for osteoporosis are present. The clinical advantage, if any, of morning dosing remains questionable.     

Early development of rat ventral root transitional zone: an immunohistochemical and morphometric study

Bundles of ventral motoneuron axons cross the white matter of the spinal cord, emerge through the cord surface at the CNS-PNS transitional zone (TZ) and continue in the PNS as ventral rootlets. This study identifies immunohistochemical and morphometric changes which characterise the key events in early TZ formation in the rat. E18 is a landmark stage, since it is then that the major events of TZ differentiation are initiated. In the glial processes associated with the TZ, vimentin expression decreases, while that of GFAP increases. In the proximal rootlets the transient expression of CNS markers such as GFAP and of neural adhesion molecules such as HNK-1/N-CAM begin to decrease. Their resulting differential expression clearly defines the CNS-PNS interface. These changes coincide with the arrival of glial nuclei at the TZ. Cell clusters which appear on proximal ventral rootlet surfaces shortly after their emergence from the cord, have by E18 formed an extensive matrix of processes which segregates the axon bundle. This comprises the earliest of two well-defined barriers across the axon bundle. An important function may be to prevent Schwann cell invasion of the cord. Cluster cells display some immunohistochemical features in common with Schwann cells. The second barrier becomes fully established only at P2 and forms the definitive CNS-PNS interface. It consists of processes arising from astrocytes surrounding the TZ. Changes in the nuclear density of the cell types correspond closely to their segregating activity. The immunohistochemical and ultrastructural changes complement one another to deepen and enhance understanding of TZ development.     

Intermingling of central and peripheral nervous tissues in rat dorsolateral vagal rootlet transitional zones

Summary The morphology of the CNS-PNS transitional zone of adult rat dorsolateral vagus nerve rootlets is uniquely complex. A typical rootlet contains a transitional zone over 300 m long, consisting of a central tissue projection extending distally into each rootlet and a peripheral tissue insertion extending for a longer distance deep into the brainstem. The peripheral tissue insertion is continuous with the peripheral tissue of the free rootlet through channels traversing or running parallel to the central tissue projection. Accordingly, the vagal CNS-PNS interface is topologically much more complex than that found elsewhere. In some rootlets the peripheral tissue in the brainstem constitutes an isolated island deep within the neuraxis. In others, peripheral continuity is established only through a cross connection with the peripheral tissue insertion of a neighbouring rootlet. About one fifth of all vagal myelinated axons alternate between the CNS and PNS tissue compartments. This distinguishes the vagus from all other nerves studied to date. These axons are myelinated by Schwann cells distal to the transitional zone, by oligodendrocytes in the central tissue projection and by one or more short intercalated Schwann internodes further centrally, mostly in the peripheral tissue insertion, where their perikarya commonly form closely apposed aggregates. More than four fifths of all unmyelinated axon bundles alternate between central and peripheral tissue compartments, commonly more than once. In the peripheral tissue insertion axons are enveloped by series of non-myelinating Schwann cells. Schwann processes commonly extend for over 50 (Am into the central compartment at each central-peripheral transition. Around one fifth of peripherally unmyelinated axons have an oligodendrocytic sheath in the central compartment. Of those axons possessing more than one intercalated Schwann internade, over one quarter display alternation of myelinated and unmyelinated segments in the peripheral tissue insertion. Astrocytes in the transitional zone segregate PNS tissue, a role played by sheath cells further peripherally in the vagal rootlets. Astrocytes form the surface limiting membranes of the central tissue projection and the barrier between the peripheral tissue insertion and the surrounding brainstem. The barrier consists only of an attenuated layer of processes. This is deficient in places, where oligodendrocytic myelin sheaths are directly exposed to the endoneurial space of the peripheral tissue insertion and in some instances are apposed to myelinating or non-myelinating Schwann cells. Such communication between the central and peripheral compartments is unique to the vagal transitional zone. The findings are consistent with a range of possible events during development. For example, considerable migration and intermingling of central and peripheral tissues, possible overgrowth of rootlet segments by developing myelencephalic tissue, failure of part of the neural crest to separate from the developing neural tube, and the origin of peripheral tissue insertion Schwann cells from the neural tube, or combinations of these factors.     

Mutations of the flavin-containing monooxygenase gene (FMO3) cause trimethylaminuria, a defect in detoxication

Individuals with the recessive condition trimethylaminuria exhibit variation in metabolic detoxication of xenobiotics by hepatic flavin- containing monooxygenases. We show here that mutations in the human flavin-containing monooxygenase isoform 3 gene ( FMO3 ) impair N - oxygenation of xenobiotics and are responsible for the trimethylaminuria phenotype. Three disease-causing mutations in nine Australian-born probands have been identified which share a particular polymorphic haplotype. Nonsense and missense mutations are associated with a severe phenotype and are also implicated in impaired metabolism of other nitrogen- and sulfur-containing substrates including biogenic amines, both clinically and when mutated proteins expressed from cDNA are studied in vitro . These findings illustrate the critical role played by human FMO3 in the metabolism of xenobiotic substrates and endogenous amines.