Philipp W. Raess

Positional cloning of Sorcs1, a type 2 diabetes quantitative trait locus.

We previously mapped the type 2 diabetes mellitus-2 locus (T2dm2), which affects fasting insulin levels, to distal chromosome 19 in a leptin-deficient obese F2 intercross derived from C57BL/6 (B6) and BTBR T+ tf/J (BTBR) mice. Introgression of a 7-Mb segment of the B6 chromosome 19 into the BTBR background (strain 1339A) replicated the reduced insulin linked to T2dm2. The 1339A mice have markedly impaired insulin secretion in vivo and disrupted islet morphology. We used subcongenic strains derived from 1339A to localize the T2dm2 quantitative trait locus (QTL) to a 242-kb segment comprising the promoter, first exon and most of the first intron of the Sorcs1 gene. This was the only gene in the 1339A strain for which we detected amino acid substitutions and expression level differences between mice carrying B6 and BTBR alleles of this insert, thereby identifying variation within the Sorcs1 gene as underlying the phenotype associated with the T2dm2 locus. SorCS1 binds platelet-derived growth factor, a growth factor crucial for pericyte recruitment to the microvasculature, and may thus have a role in expanding or maintaining the islet vasculature. Our identification of the Sorcs1 gene provides insight into the pathway underlying the pathophysiology of obesity-induced type 2 diabetes mellitus.

Cholecystokinin Is Up-Regulated in Obese Mouse Islets and Expands β-Cell Mass by Increasing β-Cell Survival

An absolute or functional deficit in beta-cell mass is a key factor in the pathogenesis of diabetes. We model obesity-driven beta-cell mass expansion by studying the diabetes-resistant C57BL/6-Leptin(ob/ob) mouse. We previously reported that cholecystokinin (Cck) was the most up-regulated gene in obese pancreatic islets. We now show that islet cholecystokinin (CCK) is up-regulated 500-fold by obesity and expressed in both alpha- and beta-cells. We bred a null Cck allele into the C57BL/6-Leptin(ob/ob) background and investigated beta-cell mass and metabolic parameters of Cck-deficient obese mice. Loss of CCK resulted in decreased islet size and reduced beta-cell mass through increased beta-cell death. CCK deficiency and decreased beta-cell mass exacerbated fasting hyperglycemia and reduced hyperinsulinemia. We further investigated whether CCK can directly affect beta-cell death in cell culture and isolated islets. CCK was able to directly reduce cytokine- and endoplasmic reticulum stress-induced cell death. In summary, CCK is up-regulated by islet cells during obesity and functions as a paracrine or autocrine factor to increase beta-cell survival and expand beta-cell mass to compensate for obesity-induced insulin resistance.

Contamination with E1A-Positive Wild-Type Adenovirus Accounts for Species-Specific Stimulation of Islet Cell Proliferation by CCK: A Cautionary Note

We have previously reported that adenovirus-mediated expression of preprocholecystokin (CCK) stimulates human and mouse islet cell proliferation. In follow-up studies, we became concerned that the CCK adenovirus might have been contaminated with a wild-type E1A-containing adenovirus. Here we show conclusively that the proliferative effects reported in the original paper in mouse and human islets were not due to CCK expression but rather to a contaminating E1A-expressing wild-type adenovirus. We also show, however, that CCK expression does have a proliferative effect in rat islets. We hope that our report of the steps taken to detect the wild-type virus contamination, and purification of the contributing viral stocks, will be helpful to other investigators, and that our experience will serve as a cautionary tale for use of adenovirus vectors, especially for studies on cellular replication.

BRAF V600E is also seen in unclassifiable splenic B-cell lymphoma/leukemia, a potential mimic of hairy cell leukemia

To the editor: The virtually 100% diagnostic sensitivity and specificity of the BRAF V600E mutation for hairy cell leukemia (HCL), within the context of mature B-cell neoplasms, originally described by Tiacci et al,[1][1] was recently confirmed in Blood .[2][2],[3][3] We report this mutation in a

Overexpression of Pre-Pro-Cholecystokinin Stimulates β-Cell Proliferation in Mouse and Human Islets with Retention of Islet Function

Type 1 and type 2 diabetes result from a deficit in insulin production and beta-cell mass. Methods to expand beta-cell mass are under intensive investigation for the treatment of type 1 and type 2 diabetes. We tested the hypothesis that cholecystokinin (CCK) can promote beta-cell proliferation. We treated isolated mouse and human islets with an adenovirus containing the CCK cDNA (AdCMV-CCK). We measured [(3)H]thymidine and BrdU incorporation into DNA and additionally, performed flow cytometry analysis to determine whether CCK overexpression stimulates beta-cell proliferation. We studied islet function by measuring glucose-stimulated insulin secretion and investigated the cell cycle regulation of proliferating beta-cells by quantitative RT-PCR and Western blot analysis. Overexpression of CCK stimulated [(3)H]thymidine incorporation into DNA 5.0-fold and 15.8-fold in mouse and human islets, respectively. AdCMV-CCK treatment also stimulated BrdU incorporation into DNA 10-fold and 21-fold in mouse and human beta-cells, respectively. Glucose-stimulated insulin secretion was unaffected by CCK expression. Analysis of cyclin and cdk mRNA and protein abundance revealed that CCK overexpression increased cyclin A, cyclin B, cyclin E, cdk1, and cdk2 with no change in cyclin D1, cyclin D2, cyclin D3, cdk4, or cdk6 in mouse and human islets. Additionally, AdCMV-CCK treatment of CCK receptor knockout and wild-type mice resulted in equal [(3)H]thymidine incorporation. CCK is a beta-cell proliferative factor that is effective in both mouse and human islets. CCK triggers beta-cell proliferation without disrupting islet function, up-regulates a distinct set of cell cycle regulators in islets, and signals independently of the CCK receptors.

Vertical sleeve gastrectomy specimens have a high prevalence of unexpected histopathologic findings requiring additional clinical management

BACKGROUND Laparoscopic vertical sleeve gastrectomy is used with increasing frequency as a therapeutic option for morbid obesity. Before the procedure, patients undergo a rigorous preoperative evaluation including double contrast upper gastrointestinal radiographic series at our institution. Patients undergoing sleeve gastrectomy are presumed to have no significant gastric pathology. OBJECTIVES To investigate the prevalence of histopathologic findings requiring clinical follow-up in sleeve gastrectomy specimens. SETTING University Hospital, United States. METHODS Retrospective review was conducted of all primary vertical sleeve gastrectomy specimens performed for morbid obesity at our institution from July 2008 until August 2012 (N = 248). RESULTS Unanticipated findings warranting clinical follow-up were identified in 8.4% of cases and included cases of H. pylori gastritis, autoimmune gastritis with microcarcinoid formation, necrotizing vasculitis, and intestinal metaplasia. H. pylori was identified in 5.2% of all cases and in 33.3% of cases of gastritis. Neoplasms were identified at laparoscopy in 2 additional cases (0.8%). CONCLUSIONS Surgeons and pathologists should be aware of the high prevalence of diagnoses requiring clinical follow-up in vertical sleeve gastrectomy specimens.

Automated screening for myelodysplastic syndromes through analysis of complete blood count and cell population data parameters.

The diagnosis of myelodysplastic syndromes (MDS) requires a high clinical index of suspicion to prompt bone marrow studies as well as subjective assessment of dysplastic morphology. We sought to determine if data collected by automated hematology analyzers during complete blood count (CBC) analysis might help to identify MDS in a routine clinical setting. We collected CBC parameters (including those for research use only and cell population data) and demographic information in a large (>5,000), unselected sequential cohort of outpatients. The cohort was divided into independent training and test groups to develop and validate a random forest classifier that identifies MDS. The classifier effectively identified MDS and had a receiver operating characteristic area under the curve (AUC) of 0.942. Platelet distribution width and the standard deviation of red blood cell distribution width were the most discriminating variables within the classifier. Additionally, a similar classifier was validated with an additional, independent set of >200 patients from a second institution with an AUC of 0.93. This retrospective study demonstrates the feasibility of identifying MDS in an unselected outpatient population using data routinely collected during CBC analysis with a classifier that has been validated using two independent data sets from different institutions. Am. J. Hematol. 89:369–374, 2014.

Tracheobronchopathia osteochondroplastica presenting as a single dominant tracheal mass.

Tracheobronchopathia osteochondroplastica is a rare, benign disorder of upper airways characterized by multiple submucosal metaplastic cartilaginous and bony nodules arising from the tracheal cartilage. We report an unusual presentation of tracheobronchopathia osteochondroplastica as a single dominant nodule arising from the anterior tracheal rings in a young adult man who presented with wheezing and symptoms of airway obstruction. The differential diagnosis of cartilaginous and bony endotracheal lesions is discussed.

Overlapping Morphologic and Immunohistochemical Features of Hashimoto Thyroiditis and IgG4-Related Thyroid Disease

Immunoglobulin G4-related disease (IgG4-RD) is an emerging clinicopathologic entity characterized by both IgG4+ plasma cell infiltration and fibrosis in one or more organs, prototypically pancreas or salivary/lacrimal glands. IgG4-RD in the thyroid (IgG4-RTD) is an area of active study, and the relationship between IgG4-RTD and Hashimoto thyroiditis is not fully delineated due to their overlapping histologic features. Retrospective review was performed of all thyroidectomy cases demonstrating lymphocytic inflammation at a single institution over a 4-year period. Approximately half (23/38) of patients had a clinical diagnosis of Hashimoto thyroiditis (HT). Nine of the 38 patients had increased absolute and relative numbers of IgG4+ plasma cells. Patients with a clinical diagnosis of HT had increased lymphoplasmacytic inflammation, but the relative proportion of IgG4+ plasma cells was not increased compared to patients without HT. There was no correlation between IgG4 levels and the amount of fibrosis in patients with or without HT. Patients identified as having the fibrosing variant of HT were not more likely to have increased levels of IgG4+ plasma cells than those without. There is significant morphologic and immunohistochemical overlap between HT and IgG4-RTD. Future studies to identify specific characteristics of IgG4-RTD involving the thyroid are necessary to accurately define this entity.

The role of molecular pathology in the diagnosis of cutaneous lymphomas.

Primary cutaneous lymphomas can be difficult to be distinguished from reactive mimics, even when integrating histologic, immunophenotypic, and clinical findings. Molecular studies, especially PCR-based antigen receptor gene rearrangement (ARGR) analysis, are frequently useful ancillary studies in the evaluation of cutaneous lymphoproliferations. The biologic basis of ARGR studies is discussed, as well as a comparison of various current protocols. The pitfalls and limitations of ARGR analysis are also highlighted. Recent advances in the understanding of the molecular pathogenesis of various cutaneous lymphomas are discussed. Some of these nascent discoveries may lead to the development of diagnostically useful molecular assays.