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author:("wynik, D.")
Neuroscience  2008;155(3):797-808.
The expression of voltage-gated sodium channels is regulated at multiple levels, and in this study we addressed the potential for alternative splicing of the Nav1.2, Nav1.3, Nav1.6 and Nav1.7 mRNAs. We isolated novel mRNA isoforms of Nav1.2 and Nav1.3 from adult mouse and rat dorsal root ganglia (DRG), Nav1.3 and Nav1.7 from adult mouse brain, and Nav1.7 from neonatal rat brain. These alternatively spliced isoforms introduce an additional exon (Nav1.2 exon 17A and topologically equivalent Nav1.7 exon 16A) or exon pair (Nav1.3 exons 17A and 17B) that contain an in-frame stop codon and result in predicted two-domain, truncated proteins. The mouse and rat orthologous exon sequences are highly conserved (94-100% identities), as are the paralogous Nav1.2 and Nav1.3 exons (93% identity in mouse) to which the Nav1.7 exon has only 60% identity. Previously, Nav1.3 mRNA has been shown to be upregulated in rat DRG following peripheral nerve injury, unlike the downregulation of all other sodium channel transcripts. Here we show that the expression of Nav1.3 mRNA containing exons 17A and 17B is unchanged in mouse following peripheral nerve injury (axotomy), whereas total Nav1.3 mRNA expression is upregulated by 33% (P=0.003), suggesting differential regulation of the alternatively spliced transcripts. The alternatively spliced rodent exon sequences are highly conserved in both the human and chicken genomes, with 77-89% and 72-76% identities to mouse, respectively. The widespread conservation of these sequences strongly suggests an additional level of regulation in the expression of these channels, that is also tissue-specific.
PMCID: PMC2726981  PMID: 18675520
DRG; brain; alternative splicing; Scn2a; Scn3a; Scn9a
2.  Obesity and Endocrine Dysfunction in Mice with Deletions of both Neuropeptide Y and Galanin 
Molecular and Cellular Biology  2004;24(7):2978-2985.
Neuropeptide Y (NPY) and galanin have both been implicated in the regulation of body weight, yet mice bearing deletions of either of these molecules have unremarkable metabolic phenotypes. To investigate whether galanin and NPY might compensate for one another, we produced mutants lacking both neuropeptides (GAL−/−/NPY−/−). We found that male GAL−/−/NPY−/− mice ate significantly more and were much heavier (30%) than wild-type (WT) controls. GAL−/−/NPY−/− mice responded to a high-fat diet by gaining more weight than WT mice gain, and they were unable to regulate their weight normally after a change in diet. GAL−/−/NPY−/− mice had elevated levels of leptin, insulin, and glucose, and they lost more weight than WT mice during chronic leptin treatment. Galanin mRNA was increased in the hypothalamus of NPY−/− mice, providing evidence of compensatory regulation in single mutants. The disruption of energy balance observed in GAL−/−/NPY−/− double knockouts is not found in the phenotype of single knockouts of either molecule. The unexpected obesity phenotype may result from the dysregulation of the leptin and insulin systems that normally keep body weight within the homeostatic range.
PMCID: PMC371109  PMID: 15024085
3.  Difficulties in localization and treatment of insulinomas in type 1 multiple endocrine adenomatosis (MEA). 
Postgraduate Medical Journal  1992;68(797):196-200.
A 15 year old girl with a family history of type 1 multiple endocrine adenomatosis presented with reversible neurological disturbances, hypoglycaemia and hyperinsulinaemia. Initial radiology was normal, but portal venous sampling suggested an insulinoma in the tail of the pancreas which was removed with conservation of the spleen. Hypoglycaemia persisted despite high doses of diazoxide and intravenous dextrose. A second laparotomy revealed a pancreatic endocrine tumour and sub-total pancreatectomy was performed. Histology revealed islet cell microadenomatosis. Hypoglycaemia persisted despite treatment with somatostatin analogues and 40% intravenous dextrose was required to maintain normoglycaemia. A possible lesion near the splenic hilum on computed tomographic scan was reported as a splenunculus although further peripheral, hepatic and portal venous sampling suggested hepatic or systemic lesions. A positron emission scan and selective visceral angiography suggested a lesion in the left upper quadrant. Acute lactic acidosis, rhabdomyolysis and renal failure supervened. Post mortem revealed the putative 'splenunculus' to be a residual insulinoma, whilst the splenic vein was thrombosed, accounting in part for discrepant venous sampling data. Hyperinsulinaemia in type 1 multiple endocrine adenomatosis may require more aggressive surgical and hormonal intervention than when dealing with solitary insulinomas. Insulinomas may mimic developmental abnormalities on computed tomographic scanning.
PMCID: PMC2399250  PMID: 1350344
4.  Gastrinoma syndrome in multiple endocrine neoplasia. 
BMJ : British Medical Journal  1990;301(6750):489-490.
PMCID: PMC1663756  PMID: 1976397

Results 1-6 (6)