Expression of Nerve Growth Factor in Human Pancreatic β Cells

Nerve growth factor (NGF) is an important modulator of rat pancreatic β-cell physiology in vitro. In this study, we analysed the expression of NGF, TrkA and insulin in human pancreatic islets from normal, ductal adenocarcinoma and insulinoma-afflicted samples, using double immunofluorescent labelling and confocal microscopy.

We found that in normal human pancreas, insulin and NGF are co-expressed in β cells. Moreover, similar to previous observations in rat, the high affinity NGF receptor TrkA is also expressed in β cells.

Pancreatic β cells in normal islets from adenocarcinoma and mucinous cystadenocarcinoma patients also expressed NGF. In 2 out of 15 exocrine tumour samples, NGF was detected also in the tissue surrounding the islets, while 2 out of 13 adenocarcinoma tumours expressed this growth factor.

In five insulinoma samples, we observed weaker immunofluorescent labelling of insulin and NGF in the neoplastic tissue, compared to the islets not afflicted by the tumour, which may be a consequence of increased hormone secretion rate.

We demonstrate that human β cells express TrkA and NGF. These findings are consistent with the hypothesis that NGF modulates insulin secretion through a paracrine/autocrine loop, similar to the one observed in cultured rat β cells.     

Expression of minichromosome maintenance 2, Ki-67, and geminin in oral nevi and melanoma

Evaluation of cell cycle using antibodies against nuclear proteins involved in regulating DNA replication has gained special interest in the effort to predict biologic behavior of benign and malignant tumors. The aim of this study was to analyze the expression of minichromosome maintenance 2, Ki-67, and geminin in oral nevi and melanomas. Expression of these cell proliferation markers was evaluated by immunohistochemistry in 49 oral melanocytic lesions, including 38 intramucosal nevi and 11 primary oral melanomas. The labeling index of each proliferation marker was assessed considering the percentage of cells expressing nuclear positivity out of the total number of cells, counting 1000 cells per slide. Minichromosome maintenance 2, Ki-67, and geminin were rarely expressed in intramucosal nevi, in contrast to oral melanomas, which showed high levels of these cell proliferation markers, particularly minichromosome maintenance 2, indicating it is a more sensitive marker in primary oral melanomas than Ki-67 and geminin. These results indicate that these markers may be involved in the pathogenesis of oral melanomas and could be eventually useful as an additional diagnostic tool for differential diagnosis of oral benign and malignant melanocytic lesions.     

Gain‐of‐Function Mutation in STIM1 (P.R304W) Is Associated with Stormorken Syndrome

Stormorken syndrome is a rare autosomal dominant disorder characterized by a phenotype that includes miosis, thrombocytopenia/thrombocytopathy with bleeding time diathesis, intellectual disability, mild hypocalcemia, muscle fatigue, asplenia, and ichthyosis. Using targeted sequencing and whole‐exome sequencing, we identified the c.910C > T transition in a STIM1 allele (p.R304W) only in patients and not in their unaffected family members. STIM1 encodes stromal interaction molecule 1 protein (STIM1), which is a finely tuned endoplasmic reticulum Ca²⁺ sensor. The effect of the mutation on the structure of STIM1 was investigated by molecular modeling, and its effect on function was explored by calcium imaging experiments. Results obtained from calcium imaging experiments using transfected cells together with fibroblasts from one patient are in agreement with impairment of calcium homeostasis. We show that the STIM1 p.R304W variant may affect the conformation of the inhibitory helix and unlock the inhibitory state of STIM1. The p.R304W mutation causes a gain of function effect associated with an increase in both resting Ca²⁺ levels and store‐operated calcium entry. Our study provides evidence that Stormorken syndrome may result from a single‐gene defect, which is consistent with Mendelian‐dominant inheritance.     

Dual-specificity phosphatases are implicated in severe hyperplasia and lack of response to FGF23 of uremic parathyroid glands from rats

Phosphate load accelerates the progression of secondary hyperparathyroidism (sHPT). In advanced stages of sHPT, there is a marked hyperplasia and resistance to classical regulatory endocrine factors such as calcium, calcitriol, or fibroblast growth factor 23 (FGF23), which suppresses PTH secretion by an ERK-dependent mechanism. Nephrectomized rats were fed with a high- or normal-phosphorus diet for different periods of time to induce sHPT. Biochemical parameters, parathyroid gland microarrays, quantitative real-time PCR, and immunohistochemistry (ERK/phospho-ERK) were performed. To test the role of dual-specificity phosphatases (Dusp) on parathyroid gland regulation, normal parathyroid glands were cultured with FGF23 and Dusp. Uremic rats fed with a high-phosphorus diet showed more severe sHPT, higher serum FGF23 levels and mortality, and decreased parathyroid Klotho gene expression. In all stages of sHPT, parathyroid microarrays displayed a widespread gene expression down-regulation; only a few genes were overexpressed, among them, Dusp5 and -6. In very severe sHPT, a significant reduction in phospho-ERK (the target of Dusp) and a significant increase of Dusp5 and -6 gene expression were observed. In ex vivo experiments with parathyroid glands, Dusp partially blocked the effect of FGF23 on PTH secretion, suggesting that Dusp might play a role in parathyroid regulation. The overexpression of Dusp and the inactivation of ERK found in the in vivo studies together with the ex vivo results might be indicative of the defense mechanism triggered to counteract hyperplasia, a mechanism that can also contribute to the resistance to the effect of FGF23 on parathyroid gland observed in advanced forms of chronic kidney disease.     

Lateral rhinotomy combined with anterior transantral approach for the treatment of large malignant melanoma of the nasal cavity involving the nasopharynx

The authors report a case of nasal malignant melanoma involving the septum, nasal turbinates and nasopharynx which was approached by lateral rhinotomy combined with an anterior transantral approach with excision of the septum and the lateral wall of the nasal cavity for wide exposure of the tumour. Using this technique complete surgical resection of a large nasal malignant melanoma was achieved with minimal morbidity and good aesthetics.