Showing papers by "Luis M. Montuenga published in 1996"

Detection of nitric oxide synthase (NOS) in somatostatin-producing cells of human and murine stomach and pancreas

Abstract: The aim of this study was to identify by immunocytochemistry the distribution of nitric oxide synthase (NOS) in human and murine gastric epithelium. Using two different antisera specific for neuronal NOS (nNOS), we detected nNOS immunoreactivity in endocrine cells of the epithelium of the body and pyloric regions as well as in ganglion cells of the intrinsic plexi of the stomach of the three species studied. Both immunocytochemistry of contiguous sections and double immunolabeling methods showed that the nNOS-immunoreactive cells were also immunoreactive for somatostatin. Co-localization of nNOS and somatostatin has also been found in the pancreatic islets, where strong nNOS immunoreactivity appeared in scattered cells, which were peripheral in rat and mouse islets and more randomly distributed in human. The possibility of crossreactivity between the antisera against nNOS and somatostatin was ruled out by means of absorption controls. Immunocytochemical techniques were also applied to thin sections, confi...

Distribution of peptidyl-glycine alpha -amidating mono-oxygenase (pam) enzymes in normal human lung and in lung epithelial tumors

Abstract: C-terminal alpha-amidation is a post-translational modification necessary for the biological activity of many regulatory peptides produced in the respiratory tract. This modification is a two-step process catalyzed by two separate enzyme activities, both derived from the peptidyl-glycine alpha-amidating mono-oxygenase (PAM) precursor. The distribution of these two enzymes, peptidyl-glycine alpha-hydroxylating monoxygenase (PHM) and peptidyl-alpha-hydroxyglycine a amidating lyase (PAL), was studied in the normal lung and in lung tumors using immunocytochemical methods and in situ hybridization. In normal lung the enzymes were located in some cells of the airway epithelium and glands, the endothelium of blood vessels, some chondrocytes of the bronchial cartilage, the alveolar macrophages, smooth muscle cells, neurons of the intrinsic ganglia, and in myelinated nerves. A total of 24 lung tumors of seven different histological types were studied. All cases contained PAM-immunoreactive cells with various patterns of distribution. All immunoreactive cells were positive for the PHM antiserum but only some of them for the PAL antiserum. The distribution of PAM co-localizes with some other previously described amidated peptides, suggesting that amidation is an important physiological process taking place in the normal and malignant human lung tissue.

Presence of Locusta diuretic hormone in endocrine cells of the ampullae of locust Malpighian tubules

Abstract: This is an investigation of an endocrine cell type in the midgut of the migratory locust Locusta migratoria. This cell type is found in the posterior region of the midgut and is especially common in the ampullae through which Malpighian tubules drain into the gut at the midgut-hindgut junction. Strong Locusta diuretic hormone-like immunoreactivity in these cells was colocalized with FMRFamide- and substance P-like immunoreactivities. At the ultrastructural level, immunoreactivity for Locusta diuretic hormone was found in spherical granules (mean diameter of 450 nm), the contents of which showed variable electron density. Fractionation of a methanolic extract of the ampullae by reversed-phase high performance liquid chromatography revealed the presence of two peaks of Locusta diuretic hormone-like immunoreactive material, both of which stimulate cyclic AMP production by isolated Malpighian tubules. The more hydrophobic material is most likely Locusta diuretic hormone, which has the same retention time when chromatographed under identical conditions.

Expression of peptidyl-glycine alpha-amidating mono-oxygenase (PAM) enzymes in morphological abnormalities adjacent to pulmonary tumors.

Abstract: Carboxyl-terminal amidated peptide hormones are known to be autocrine growth factors for lung tumors and tumor cell lines. Expression of the enzymes necessary for the biosynthesis of active amidated peptide hormones is therefore necessary for autocrine growth stimulation in lung tumors and possibly in the early proliferative stages of lung carcinogenesis. The peptidyl amidating enzymes have previously been identified in cell lines of all histological types of lung cancer and in lung tumors by immunohistochemistry and in situ hybridization. In this study we analyzed the expression of the peptidyl amidating enzymes in histological abnormalities found in the proximity of pulmonary tumors from a series of 59 patients. Most of the lesions in both the proximal airways (basal cell hyperplasia, carcinoma in situ, and some squamous metaplasia) and the alveoli (type II cell hyperplasia, bronchiolization of the alveoli, atypical alveolar hyperplasia, and isolated atypias) had a high proportion of cells strongly positive for the peptidyl amidating enzymes. The intense expression of peptidyl amidating enzymes in type II cell hyperplasia and atypical alveolar cells, together with the high frequency of these abnormalities in the alveoli, which is an area that does not express these enzymes in normal lung, points to the involvement of peptide hormones in the growth biology of pulmonary tumors. These findings suggest that peptide hormone stimulation of mitogenesis is an early event in tumor progression and merits additional investigation as a target for early detection and chemo-intervention of lung carcinogenesis.