High glucose causes apoptosis in cultured human pancreatic islets of Langerhans: a potential role for regulation of specific Bcl family genes toward an apoptotic cell death program.

Type 2 diabetes is characterized by insulin resistance and inadequate insulin secretion. In the advanced stages of the disease, beta-cell dysfunction worsens and insulin therapy may be necessary to achieve satisfactory metabolic control. Studies in autopsies found decreased beta-cell mass in pancreas of people with type 2 diabetes. Apoptosis, a constitutive program of cell death modulated by the Bcl family genes, has been implicated in loss of beta-cells in animal models of type 2 diabetes. In this study, we compared the effect of 5 days' culture in high glucose concentration (16.7 mmol/l) versus normal glucose levels (5.5 mmol/l) or hyperosmolar control (mannitol 11 mmol/l plus glucose 5 mmol/l) on the survival of human pancreatic islets. Apoptosis, analyzed by flow cytometry and electron and immunofluorescence microscopy, was increased in islets cultured in high glucose (HG5) as compared with normal glucose (NG5) or hyperosmolar control (NG5+MAN5). We also analyzed by reverse transcriptase-polymerase chain reaction and Western blotting the expression of the Bcl family genes in human islets cultured in normal glucose or high glucose. The antiapoptotic gene Bcl-2 was unaffected by glucose change, whereas Bcl-xl was reduced upon treatment with HG5. On the other hand, proapoptotic genes Bad, Bid, and Bik were overexpressed in the islets maintained in HG5. To define the pancreatic localization of Bcl proteins, we performed confocal immunofluorescence analysis on human pancreas. Bad and Bid were specifically expressed in beta-cells, and Bid was also expressed, although at low levels, in the exocrine pancreas. Bik and Bcl-xl were expressed in other endocrine islet cells as well as in the exocrine pancreas. These data suggest that in human islets, high glucose may modulate the balance of proapoptotic and antiapoptotic Bcl proteins toward apoptosis, thus favoring beta-cell death.

[Malignant myoepithelioma associated with in situ and invasive ductal carcinoma. Description of a case and review of the literature]. / Mioepitelioma maligno associato a carcinoma duttale in situ ed invasivo NAS. Descrizione di un caso e revisione della letteratura.

A case of malignant myoepithelioma of the breast, associated with in situ and invasive carcinoma NOS is described. Myoepithelial differentiation was demonstrated with immunohistochemistry and electron microscopy. The tumour affected the left breast of a 72 year old lady. The patient had been treated with quadrantectomy with axillary dissection, followed by radiotherapy. At the time of diagnosis no local or distant metastases were found. Bone, pulmonary and cerebral metastases appeared 28 months after treatment. Malignant myoepitheliomas share histological and immunohistochemical features with monophasic sarcomatoid carcinomas. Comparison and and possible relationship with monophasic sarcomatoid carcinomas is discussed.

Benign regressing histiocytosis of the liver.

A case of benign regressing histiocytosis of the liver is reported. The patient, an adult male, presented with fever and diarrhoea and on abdominal echography multiple nodules were present in the liver. Histologically and immunohistochemically the lesions had features of Langerhans' cell histiocytosis. The nodules regressed within four months, without therapy, and the patient is free of disease 29 months after presentation.

Well-differentiated endocrine tumours of the middle ear and of the hindgut have immunocytochemical and ultrastructural features in common.

The immunocytochemical analysis of two cases of well-differentiated endocrine tumours (carcinoids) of the middle ear revealed predominant cell populations producing pancreatic polypeptide (PP)-related peptides, glucagon-related peptides, and serotonin (the latter only in one case). In consecutive sections PP- and glucagon-related immunoreactivities mainly colocalized in the same tumour cells. Ultrastructurally tumour cells were characterized by medium-sized to large granules of moderate to high density, on which PP and glicentin were localized by the immunogold technique. No amphicrine cells were found. These features are consistent with those of similar tumours in the rectal mucosa that are mainly composed of L cells coexpressing both PP-related and glucagon-related peptides. Additional tumour antigens of hindgut type detected immunohistochemically were prostatic acid phosphatase and CAR-5 mucin. Expression of the CAR-5 antigen was also found in samples of normal middle ear mucosa, in which endocrine cells have not been identified. In case 1 peritumoral mucosal invaginations showed a proliferation of endocrine cells identical immunophenotypically to tumour cells, possibly representing a precursor lesion. It is concluded that well-differentiated endocrine tumours of the middle ear are a distinct pathological entity characterized by multiple hormone production, typically involving three classes of hormones (pancreatic polypeptide-related peptides, glucagon-related peptides, and serotonin) of the hindgut endocrine system.

Different expression of chromogranin A and chromogranin B in various types of pituitary adenomas.

Two hundred and nineteen (33 GH, 21 GH-PRL, 38 PRL, 16 ACTH, 1 TSH cell functioning and 38 FSH-LH, 17 alpha-chain, 8 mixed, 27 minimal glycoprotein--MIN-GLYC--, 11 small argyrophil granule--SAG--, 4 silent TSH-sTSH--and 5 silent ACTH-sACTH--cell nonfunctioning) adenomas were investigated immunohistochemically with antibodies against ACTH, GH, PRL, TSH, FSH, LH alpha-hCG, chromogranin A (CgA) and chromogranin B (CgB). For immunostaining of CgB a novel monoclonal (B 11) antibody was employed. All types of adenomas were positive for CgB. CgA was widely expressed in nonfunctioning FSH-LH, MIN-GLYC, SAG, MIXED, alpha-chain adenomas and in the single TSH cell functioning adenoma. CgA was lacking both in PRL and ACTH functioning adenomas and was poorly expressed in GH and GH-PRL functioning adenomas. The distribution of Grimelius' silver paralleled that of CgA-IR, but not that of CgB-IR. We conclude that: 1) CgB may be considered as an universal granular marker for pituitary adenomas, 2) CgA is an important marker for nonfunctioning adenomas, 3) the pattern of distribution of CgA and CgB for most nonfunctioning ("null cell" according to Kovacs et al.) adenomas favors their origin from glycoprotein producing (FSH/LH, TSH) cells.

Ovarian mucinous tumors frequently express markers of gastric, intestinal, and pancreatobiliary epithelial cells.

In 100 mucinous tumors of the ovary (37 benign, 24 borderline, and 39 malignant), the authors determined by histochemical and immunohistochemical techniques the frequencies and patterns of expression of a total of nine markers of gastric, intestinal, and pancreatobiliary duct epithelial cells. M1, a mucin antigen, and cathepsin E (CaE), an aspartic proteinase, two markers of normal gastric superficial/foveolar epithelial cells, were expressed in 95 and 92 tumors, respectively. Periodic acid-concanavalin A-reactive mucin or pepsinogen (PG) II, markers of gastric mucus neck and pyloric gland cells, were found in 79 tumors. All of these tumors also expressed M1 or CaE. DU-PAN-2 and the N-terminal epitope of gastrin-releasing peptide, markers of normal pancreatobiliary duct cells, were found in 70 and 49 tumors, respectively, and CAR-5 and M3SI, markers of intestinal mucin, were expressed in 51 and 30 tumors, respectively. All tumors expressed at least two of the nine markers studied; none expressed PG I, a marker of gastric chief cells. The mucopeptic cell marker, PG II, was significantly more common in benign and borderline than in malignant tumors (P less than 0.005), whereas CAR-5 and M3SI, markers of intestinal mucin, were expressed significantly more often in malignant than in benign and borderline tumors (P less than 0.001). By electron microscopic examination, many tumor cells had fine structural features characteristic of gastric superficial/foveolar and pyloric gland cells, intestinal columnar or goblet cells, and endocervical cells. The results indicate that gastroenteropancreatic cell differentiation--and, in particular, gastric type differentiation--is a prominent feature of ovarian mucinous tumors.

Ultrastructural features of neuroendocrine differentiated carcinomas of the breast.

The ultrastructural patterns of neuroendocrine (NE) differentiated breast carcinomas are analyzed and discussed. Reports in the literature describe wide variations in the size of observed dense-core membrane-bound granules and discrepancies in their interpretation. In the present study 24 cases of breast carcinoma with recognized morphologic, histochemical, and immunocytochemical features of NE tumors were investigated. Five different types of dense-core granules of neurosecretory (NS) type (confirmed by the ultrastructural localization of chromogranin A) and five different cell types were recognized. Some amphicrine cells were found to contain both mucin and NS granules. Another notable ultrastructural feature of breast NE carcinomas was the presence of clear vesicles of presynaptic type, which correlated with expression of synaptophysin.

Endocrine tumors of the duodenum and upper jejunum. A study of 33 cases with clinico-pathological characteristics and hormone content.

Thirty duodenal and three upper-jejunal endocrine tumors are reported. Clinical manifestations included: a) the Zollinger-Ellison syndrome (10 cases); b) peptic ulcer disease in which hypergastrinemia was not documented (3 cases); c) cholestasis or cholelithiasis (4 cases); d) abdominal pain (4 cases); e) gastro-intestinal bleeding (1 case); f) celiac sprue (1 case). Ten further tumors were discovered incidentally, at autopsy or in pathological specimens after gastrectomy or duodenopan-createctomy. Histological pattern was trabecular in 19 cases, insular in 2 and mixed in ten cases. Two cases were typical ganglioneuromatous paragangliomas. All tumors were examined immunohistochemically. Twelve tumors contained gastrin, four somatostatin, six both of these peptides, one serotonin, two both gastrin and serotonin, and two tumors contained gastrin, serotonin and somatostatin. Ganglioneuromatous paragangliomas combined somatostatin and/or pancreatic polypeptide containing endocrine cells with protein-S100-positive Schwann cells. In four tumors no peptide or amine was demonstrated. Gastrin cell tumors (63.6% of our cases), both functionally active (gastrinomas) and clinically silent, predominated in the proximal duodenum, while somatostatin cell tumors (15.1%) and paragangliomas were mostly found in the periampullary region. Two tumors were classified as malignant on the basis of lymph node metastases, and both were jejunal gastrinomas associated with Zollinger-Ellison syndrome. Two somatostatin cell tumors had manifestations of von Recklinghausen's disease.

Ultrastructural identification of human secretin cells by the immunogold technique. Their costorage of chromogranin A and serotonin.

We have localized secretin in a morphologically distinctive endocrine cell scattered in the epithelium covering the villi and uppermost crypts of the human duodenum and jejunum. The human secretin cell was characterized by relatively large (mean diameter 299 nm +/- 69 SD), fairly irregular granules, the majority of which showed homogeneous distribution of secretin and chromogranin A immunolabelling in a structurally homogeneous core. Other granules had a targetoid pattern due to an inner, argyrophobe, secretin-immunoreactive body surrounded by an argyrophil, chromogranin A immunoreactive mantle. These targetoid granules represent a distinctive ultrastructural marker of the secretin cell. Secretin cell granules have been shown to react with chromogranin A antibodies and Grimelius' silver, while lacking chromogranin B immunoreactivity. About 1/3 of secretin cells also showed serotonin immunostaining.

Endocrine cells producing regulatory peptides.

Recent data on the immunolocalization of regulatory peptides and related propeptide sequences in endocrine cells and tumors of the gastrointestinal tract, pancreas, lung, thyroid, pituitary (ACTH and opioids), adrenals and paraganglia have been revised and discussed. Gastrin, xenopsin, cholecystokinin (CCK), somatostatin, motilin, secretin, GIP (gastric inhibitory polypeptide), neurotensin, glicentin/glucagon-37 and PYY (peptide tyrosine tyrosine) are the main products of gastrointestinal endocrine cells; glucagon, CRF (corticotropin releasing factor), somatostatin, PP (pancreatic polypeptide) and GRF (growth hormone releasing factor), in addition to insulin, are produced in pancreatic islet cells; bombesin-related peptides are the main markers of pulmonary endocrine cells; calcitonin and CGRP (calcitonin gene-related peptide) occur in thyroid and extrathyroid C cells; ACTH and endorphins in anterior and intermediate lobe pituitary cells, alpha-MSH and CLIP (corticotropin-like intermediate lobe peptide) in intermediate lobe cells; met- and leu-enkephalins and related peptides in adrenal medullary and paraganglionic cells as well as in some gut (enterochromaffin) cells; NPY (neuropeptide Y) in adrenaline-type adrenal medullary cells, etc.. Both tissue-appropriate and tissue-inappropriate regulatory peptides are produced by endocrine tumours, with inappropriate peptides mostly produced by malignant tumours.

Growth hormone-releasing factor does not stimulate phosphoinositides breakdown in primary cultures of rat and human pituitary cells.

It has been reported that rat growth hormone releasing factor (rat GRF-43), similarly to the two human GRFs (GRF-40 and 44) stimulates adenylate cyclase activity in pituitary cells. Controversial findings have been presented by two different groups on the action of GRF on phosphoinositides (PI) metabolism, a phenomenon linked to Ca-- mediated intracellular mechanisms. In the work to be reported, we evaluated the accumulation of inositol phosphates induced by GRF exposure in primary cultures of rat and human pituitary cells. Addition of rat GRF-43 to rat pituitary cells at doses up to 1 microM had no effect on inositol phosphates accumulation, while already at a dose as low as 0.05 nM it increased growth hormone secretion in the incubation medium significantly. In the same cell system, TRH, a known activator of PI breakdown, significantly increased [3H]inositol phosphates. In primary cultures of human somatotrophs from acromegalic subjects as in rats, addition of hpGRF-40 and also of TRH did not elicit any modification in the accumulation of [3H]inositol phosphates. Consistent with in vivo findings, both peptides induced a significant release of GH in the medium. Our results show that the GH releasing effect of GRF does not involve the hydrolysis of phosphatidylinositol in normal rat as well as in tumoral human somatotrophs. In addition it appears that the anomalous response of TRH on adenomatous cells from acromegalic patients is differently mediated in respect to the action of the tripeptide on normal lactotrophs and thyrotrophs.

Regulatory peptides in neuronal neoplasms of the central nervous system.

Neuronal tumors of CNS were examined immunohistochemically for regulatory peptides. Thirteen ganglion cell neoplasms, one cerebellar ganglioneuroblastoma, one cerebellar neuroblastoma, and four medulloblastomas were studied. Sixteen non-neuronal intracranial neoplasms were examined as controls. Immunoreactive vasoactive intestinal polypeptide (VIP) was observed in seven cases of ganglion cell neoplasm and in the one cerebellar ganglioneuroblastoma. The cerebellar neuroblastoma, all of the medulloblastomas, and all of the non-neuronal intracranial neoplasms were negative. Four additional ganglion cell neoplasms were tested for the presence of neurotensin and somatostatin. Two contained neurotensin. The results suggest that CNS ganglion cell neoplasms share with their extracranial counterparts the production of certain hormonal polypeptides. Since these peptides are presumed to be specific markers for neurons, the immunohistochemical detection of these substances may provide diagnostically useful technique in the diagnosis of such lesions.

Tryptophyllin-like immunoreactivity in rat adenohypophysis.

A new amphibian peptide family has been isolated from the skin of a South American frog Phyllomedusa rhodei and named Tryptophyllins (TPH) because of their content in tryptophyl residue. Using an antiserum against one of these peptides, namely the pentapeptide Met-5-TPH-5-amide (PHE-PRO-PRO-TRP-MET-NH2), we observed the presence of a set of immunoreactive cells in rat adenohypophysis. These cells were far more numerous in pregnant than in normal male and non-pregnant female rats. Dual immunostainings demonstrated that, with some exceptions, almost all the TPH-like immunoreactive cells were gonadotrophs. At electron microscope both types of gonadotroph cells displayed immunoreactivity and the gold particles strongly labelled both types of granules. The Aa. advance the hypothesis that, besides the hormones themselves, the secretory granules might contain some TPH-like sequence.

Ultrastructural localization of cholecystokinin in endocrine cells of the dog duodenum by the immunogold technique.

Cholecystokinin (CCK) has been localized by the immunogold technique in a type of endocrine cell of the dog duodenum characterized by small (166 +/- 38 nm) secretory granules with fairly dense, homogeneous core separated from its enveloping membrane by a thin clear space. The CCK cell is immunocytochemically distinct and cytologically different from other types of endocrine cells, as the secretin, GIP and motilin cells, already identified in the dog duodenum.

Glucagon- and PP-related peptides of intestinal L cells and pancreatic/gastric A or PP cells. Possible interrelationships of peptides and cells during evolution, fetal development and tumor growth.

The immunohistochemical detection of six distinct sequences of proglucagon and its derivatives (GRPP, glicentin, glucagon-37, glucagon-29, GLP1, GLP2 and MPGF) in both intestinal L cells and pancreatic or gastric A cells of some mammals (dog, man, guinea pig) confirms that the two cell types produce the same proglucagon molecule, although the final step of its post-translational processing differs in the two cells. Immunohistochemical and ultrastructural patterns of glucagon/glicentin cells in the pancreas of lower vertebrates and early human fetuses, as well as tumor cell studies, suggest an evolution of gastropancreatic A cells from L cells. On the contrary, the PP-related peptide PYY of intestinal L cells, and PP with its C-terminal icosapeptide extension of pancreatic PP cells, likely originate from different prohormones. Although intermediate patterns of peptide expression can be observed, including some F-type PP cells of the dog pancreas (uncinate process) and pyloric mucosa showing PYY immunoreactivity or rare PYY and/or HPP immunoreactive cells of the human rectum lacking glicentin reactivity, no obvious relationship can be established between L cells and pancreatic (F-type) PP cells. However, some evolutionary, embryogenetic and oncogenetic link may exist between L cells and human D1-type PP cells, a minor population of PP cells scattered in the pancreatic tissue of dorsal pouch origin and a major fraction of tumor PP cells.

The contribution of immunohistochemistry to the diagnosis of neuroendocrine tumors.

The use of specific secretory products, hormones, and neuroregulators as diagnostic tools for neuroendocrine tumors is illustrated. Results of extensive immunohistochemical and cytologic investigations are discussed in the light of other pathologic and clinical findings to serve as a basis for tumor classification and as a help in prognostic evaluation. Endocrine tumors of the pancreas, gut, lung and urogenital tract are dealt in some detail.

Ultrastructural localization of secretin in endocrine cells of the dog duodenum by the immunogold technique. Comparison with ultrastructurally characterized S cells of various mammals.

Secretin has been localized by the immunogold technique in endocrine cells of the dog duodenum--previously described as "K cells"--characterized by secretory granules with double structure consisting of a secretin-containing osmiophilic core surrounded by an argyrophil halo. Granules resembling those of dog secretin cells were also found in some ultrastructurally characterized S cells of the cat, pig, rat and rabbit duodenum, thus confirming in these species the identification of S cells with secretin cells. Conversely, the cells previously described as "S cells" in the dog lacked secretin immunoreactivity.

Ultrastructural localization of motilin in endocrine cells of human and dog intestine by the immunogold technique.

Motilin-immunoreactivity has been localized by two electron immunocytochemical techniques, using gold-labelled protein A or IgG as second layer, in a specific type of endocrine cell scattered in the epithelium of human and canine upper small intestine. The motilin (M) cell is characterized by relatively small (180 nm in man; 200 nm in the dog), solid granules with homogeneous core and closely applied membrane, round in man, round to irregularly-shaped in the dog. Perinuclear microfilaments are prominent in human motilin cells.

Ultrastructural localization of gastric inhibitory polypeptide (GIP) in a well characterized endocrine cell of canine duodenal mucosa.

The polypeptide hormone GIP has been localized ultrastructurally by using specific, monoclonal GIP antibodies and an immunogold technique on aldehyde-osmium fixed specimens of dog duodenal mucosa. A single type of cell showing round, homogeneous, fairly osmiophilic granules with closely applied membrane and a mean size of 188 nm +/- 34 SD has been identified as the GIP cell.