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Biomedical subjects

D Grube

Publications and source records attributed to D Grube.

At least 55 records · Page 3Linked to original sources
PubMed1986

The endocrine cells of the digestive system: amines, peptides, and modes of action.

The endocrine cells of the digestive system (entero-endocrine cells of gastro-intestinal epithelia and Langerhans' islets of the pancreas) and the chemical messengers produced by them constitute a complicated and complex system. The physiological function of this system is the regulation of all processes related to digestion and resorption, and to homeostasis of carbohydrate metabolism. Using morphological and histochemical features of this cellular community, the present review deals with amines and amine metabolism, polypeptides and their immunohistochemical identification, and with the modes of action of enteric and pancreatic hormones. Special attention is paid to the significance of amine precursor uptake and decarboxylation (APUD), to immunohistochemical methodology and the interpretation of immunohistochemical findings, and to local regulatory mechanisms, especially paracrinia. Finally, unifying concepts for the integration of these cells and similar endocrine cells of other organs into a common system are considered.

APUD Cells↗
PubMed1986

Chromogranin A (CGA) in the gastro-entero-pancreatic (GEP) endocrine system. I. CGA in the mammalian endocrine pancreas.

Chromogranin A (CGA), a protein at first detected in the adrenal medulla, has recently been found also in other organs, e.g. the endocrine pancreas. However, immunohistochemical findings concerning the cellular source of pancreatic CGA were controversial. Therefore, the endocrine pancreas of 10 mammalian species (man, tupaia, mole, cat, dog, pig, guinea pig, rabbit, rat) was investigated immunohistochemically for CGA-like immunoreactivities on serial semithin plastic sections using a high-titer polyclonal antiserum against bovine CGA. The results show that basically all pancreatic endocrine cell types are CGA-immunoreactive; however, every species has its own pattern of CGA-immunoreactive cell types. Other findings of the present studies indicate that the physiological function of CGA in pancreatic endocrine cells is related to the storage mechanisms of peptide hormones. Finally, a methodological approach is given to obtain not only qualitative but also semi-quantitative data during immunohistochemical investigations.

Animals↗
PubMed1986

Chromogranin A in the pancreatic islet: cellular and subcellular distribution.

Chromogranin A (CGA) is the major soluble protein within secretory vesicles of chromaffin cells. A polyclonal antiserum was raised against bovine CGA and characterized in two-dimensional immunoblots. Cellular and subcellular distribution of CGA in bovine pancreatic islet was investigated by immunocytochemistry. At the light microscopic level, CGA-like immunoreactivity was found in the same cells that react with antibodies against insulin, glucagon, and somatostatin. A minority of cells containing pancreatic polypeptide also showed faint immunostaining. At the ultrastructural level (protein A-gold technique), CGA-like immunoreactivity was confined exclusively to the secretory vesicles. Whereas the hormones were localized mainly in the central part of the secretory vesicles, CGA was present predominantly in the periphery. These findings indicate that a CGA-like protein is a regular constituent of the matrix of secretory vesicles in pancreatic endocrine cells.

Animals↗
PubMed1986

Serial semithin sections in immunohistochemistry: techniques and applications.

Immunostaining of semithin sections is a valuable tool in biomedical research; however, this method is rather rarely used by histologists. To overcome the apparent reservations concerning this method, the present report describes a technique which is rather simple, largely standardized, and very useful in investigative endocrinology. The technique includes the following steps: snap-freezing and freeze-drying of tissue specimens, embedding in Araldite, preparation of serial semithin sections, removal of the resin from tissue sections, immunostaining with Sternberger's peroxidase antiperoxidase (PAP) technique, and analyses of the sections by various microscopical techniques which in part optically enhance immunoreactive sites. In addition to a detailed description of the method, examples for its applications are given, including concomitant investigations of the same cells by empirical staining, immunostaining, and fluorescence histochemistry of biogenic monoamines; colocalization of multiple peptides to the same cells and corresponding specificity controls; three-dimensional reconstructions based upon immunostained serial semithin sections; quantitative (computer-assisted) determinations of immunoreactivities. Because of the advantages offered by immunostained serial semithin sections as well as the vast field of applications, the method described is recommended for routine use. Concomitantly this method covers the gap between conventional light microscopy (paraffin sections) and electron microscopy.

Animals↗
PubMed1983

Somatostatinoma syndrome. Clinical, morphological and metabolic features and therapeutic aspects.

A case of somatostatinoma syndrome in a 30-year-old woman is presented. Basal levels of growth hormone and of pancreatic and gastric hormones were reduced and the response of growth hormone, insulin and C-peptide to stimuli such as arginine, glucose, glibenclamide and calcium was virtually abolished. Similarly, gastric acid secretion, pancreatic exocrine function and intestinal absorption were significantly reduced. On the other hand, basal and stimulated levels of adrenocorticotropic hormone (ACTH), luteinizing hormone (LH), follicle-stimulating hormone (FSH) and thyroid-stimulating hormone (TSH) were within the normal range. Plasma somatostatin-like immunoreactivity was increased to 600-2,000 pg/ml (normal: 88-140 pg/ml). Immunocytochemical studies demonstrated the presence of somatostatin immunoreactive material in the primary tumour in the head of the pancreas and in the liver metastases. In spite of two courses of chemotherapy with streptozotocin and 5-fluorouracil the patient died due to liver failure 5 months after the first admission to hospital.

Adenoma, Islet Cell↗
PubMed1983

The microanatomy of human islets of Langerhans, with special reference to somatostatin (D-) cells.

The arrangement of the various endocrine cells within mammalian islets of Langerhans indicates that the regulation of insulin and glucagon secretion by pancreatic somatostatin may occur mainly by paracrine mechanisms. In the present study, the relationship of somatostatin-containing D-cells to blood vessels and to other endocrine cells in the islets of the human pancreas were investigated using immunohistochemically stained serial semithin sections (0.5-1.0 micron). Morphologic features of 335 D-cells were examined and their anatomical relationship to other endocrine cell types and capillaries was determined by morphometric analysis and graphic or three-dimensional reconstructions. The majority of D-cells (84%) was located in close proximity to the capillaries. The intracellular immunoreactive material was accumulated in those cell parts facing the capillaries or their perivascular spaces. The remaining D-cells did not come into contact with the capillaries and showed only moderate or weak immunoreactivity.--A further characteristic feature of islet D-cells, pertinent to about 67% of these cells, is their tendency to be arranged in contiguity to other D-cells. The present findings indicate that somatostatin after its release from the D-cell reaches other islet cells mainly via the intrainsular circulation or along the perivascular space. Concerning the general microarchitecture of human islets of Langerhans, the present data are not sufficient to give a conclusive morphological description, because heterogeneities among the islets were observed. These variations appear to be related to the type of vascular supply which differs among islets.

Aged↗
PubMed1982

[The endocrine cells of the digestive system (author's transl)].

Endocrine cells occur in the digestive system as micro-organs (islets of Langerhans) or scattered throughout the epithelium of the gastrointestinal tract ("diffuse endocrine epithelial organ" of Feyrter). These gastro-entero-pancreatic (GEP) endocrine cells synthesize--in addition to serotonin--a great variety of polypeptide hormones, which regulate both carbohydrate metabolism and digestive processes. The present review deals mainly with cytology and cytochemistry of GEP endocrine cells. A synopsis is presented of the 19 endocrine cell types identified to date, which includes their update nomenclature and their anatomical distribution pattern. Morphological-functional aspects of cell biology, pathology, and cytogenesis of theses cells and their position within superimposed systems (APUD cells, paraneurons) are discussed.

APUD Cells↗
PubMed1981

A multihormonal tumor of the pancreas producing neurotensin.

In a pancreatic adenoma approximately 78.7% of the endocrine cells reacted specifically with antisera to neurotensin, 17.5% to gastrin, 2.8% to pancreatic polypeptide, and 1% to glucagon. The electron microscope revealed that the majority of the endocrine cells were N-cells--morphologically similar to the ileal N-cells which are known to represent the neurotensin-producing cells. Neurotensin was extracted from the tumor and identified by Sephadex, ion-exchange, and high-pressure liquid chromatography. Gastrin, pancreatic polypeptide, and glucagon cells were also identified by the electron microscope; the peptides were extracted and demonstrated by chromatography. The serum concentrations of these hormones were elevated. After total gastrectomy which was necessary because of Zollinger-Ellison syndrome, a jejunoesophageal alkaline reflux, reaching the upper esophagus appeared. As intravenous infusion of synthetic neurotensin in rats caused an increase of luminal enteric pressure, it is suggested that severe jejunoesophageal reflux after gastrectomy may be a clinical feature of a neurotensinoma.

Adenoma↗
PubMed1981

[Specificity control in the immunohistochemistry of enteral peptide hormones].

A great variety of peptide hormones have been demonstrated by immunocytochemical means in endocrine cells of the digestive system. Usually the specificity immunostaining in these cells is checked by antigen-adsorption of the antisera. This kind of specificity control, however, examines only antibody non-specificity but not staining non-specificity. Indeed staining non-specificities caused by ionic binding mechanisms are of considerable significance, at least for the immunostaining of some endocrine cell types (e.g. pancreatic glucagon- and PP-cells, pyloric gastrin-cells, intestinal GLI-cells). Therefore immunoreactivities of these cell types should be investigated under various experimental conditions. According to our present findings the following investigations should be performed to exclude staining non-specificities in immunostained endocrine cells of the digestive system: 1. Running of ascending dilutions of primary and secondary antisera. 2. Comparative investigations using crude antisera and purified antibodies against the peptide in question. 3. Use of phosphate buffered saline (PBS) with a relatively high salt content as a dilution agent for the antisera.

Animals↗
PubMed1980

Endocrine GEP-cells in primary testicular teratoma.

Differentiated teratomas frequently contain the apparent equivalent of gastrointestinal mucosa. 53 testicular teratomas were investigated for the incidence of entero-endocrine cells. Enterochromaffin(EC)-cells were demonstrated by formaldehyde induced fluorescence (FIF), while the other endocrine cells were identified by immunohistochemistry. 11 of 53 teratomas contained endocrine cells associated with the gastrointestinal epithelium. The most frequently found cell type was the EC-cell, followed by somatostatin-, glucagon- and pancreatic polypeptide-immunoreactive cells. The teratoma tissue blocks (20 of 53) also frequently exhibited normal testicular tissue which did not contain any EC-cell or other entero-endocrine cells. The results are of interest in considering the cytogenesis of entero-endocrine cells and the histogenesis of testicular carcinoids, indicating that the entero-endocrine cells derive from the intestinal carcinoids, indicating that the entero-endocrine cells derive from the intestinal epithelium arising from undifferentiated stem cells. Furthermore, it seems probable that primary testicular carcinoids can develop from pre-existent teratomas by proliferation of their entero-endocrine cells.

Cell Differentiation↗
PubMed1980

Immunoreactivities of gastrin (G-) cells. I. dilution-dependent staining of G-cells by antisera and non-immune sera.

Results of immunocytochemical studies reported by several laboratories suggest that gastrin (G-) cells of the stomach show immunoreactivities for various pituitary hormones (ACTH, met-enkephalin, beta-endorphin and growth hormone) in addition to gastrin. By reinvestigating the immunocytochemistry of G-cells we found that these cells exhibited reactivities towards a variety of antisera against enteric, pancreatic and hypophyseal hormones. Gastrin cells can also be "immunostained" by antisera towards proteins unrelated to any peptide hormones (e.g. alpha-fetoprotein antiserum) and by nonimmune sera. Thus the specificity of immunocytochemical findings in G-cells seems to be uncertain. According to our findings the polyvalent immunoreactivities of G-cells may be caused by a distinct binding capacity for IgG molecules. This binding of IgG to G-cells seems to be mediated by the Fab fragments of the IgG molecules which may behave like a basic dye and therefore "immunostain" anionic components within G-cells. Thus the significance of the immunocytochemical proof of peptide hormones within G-cells is limited unless extended specificity controls have been performed. The results of specificity controls performed in this study (adsorption controls, use of ascending dilutions of the primary and secondary antisera, comparison of crude antisera and affinity chromatographically purified antibodies) suggest that corticotropin-lipotropin related peptides are not contained in G-cells.

Adrenocorticotropic Hormone↗
PubMed1980

Immunoreactivities of gastrin (G-) cells. II. Non-specific binding of immunoglobulins to G-cells by ionic interactions.

Various gastro-entero-pancreatic (GEP) endocrine cells have been shown to contain concomitantly immunoreactivities against several peptide hormones. In the present study the "immunoreactivities" of gastrin (G-) cells of the rat stomach against 21 specific antisera and 10 control sera were investigated by means of the unlabelled antibody enzyme (PAP) technique using modifications of single steps in the immunocytochemical staining sequence. The results indicate that immunoglobulins can bind to gastrin cell granules obviously by non-specific ionic interactions. This non-specific binding of immunoglobulins occurs even in dilution ranges of the sera commonly used in immunohistochemical investigations of the GEP endocrine system. Since "adsorption controls" (preadsorption of the antisera with their respective antigens) will not discriminate between specific and non-specific binding of immunoglobulins to GEP endocrine cells additional specificity controls are necessary. In contrast to the immunostaining of various GEP endocrine cells by "established" antisera and of G-cells by gastrin antiserum immunoglobulins of sera from non-immunized animals as well as antibodies against corticotropin-lipotropin related peptides could be displaced from their binding sites in G-cells by alterations of the NaCl content of the buffers used as diluents or as rinsing solutions. To exclude immunostaining of GEP endocrine cells by nonspecific binding of immunoglobulins the following working procedures are recommended for immunocytochemical investigations of these cells: 1. Use of high titer antisera at low concentrations (diluted 1:1,500 or more). 2. Elevation of the salt (NaCl) content up to 0.5 M of the buffer used as diluent or as rinsing solution. 3. Adsorption controls will show reliable results only if point 1. and 2. have been taken into account.

Animals↗
PubMed1980

Immunoperoxidase methods: increased efficiency using fluorescence microscopy for 3,3-diaminobenzidine (DAB) stained semithin sections.

When semithin sections stained by immunoperoxidase-DAB methods are exposed to ultraviolet light in a fluorescence microscope, immunoreactive cells develop a strong yellowish fluorescence within 2-4 min. This property offers the possibility of visualizing even reaction products which can barely be identified by other microscopical techniques. Thus the efficiency of immunoperoxidase methods is greatly enhanced. Moreover the histochemical proof of endogenous peroxide active enzymes visualized with DAB as substrate may also be facilitated using fluorescence microscopy.

3,3'-Diaminobenzidine↗
PubMed1980

Alpha-endorphin-like immunoreactivity in plasma cells of the canine colonic mucosa.

During immunocytochemical investigations on the presence of opioid peptides in gastrointestinal endocrine cells it was found that a subpopulation of plasma cells located in the lamina propria of the canine colonic mucosa showed immunoreactivities for alpha-endorphin. All immunohistochemical specificity controls proved the specificity of the reaction. Circumstantial evidence suggest, however, that no authentic alpha-endorphin is present within this cell type. Possibly sequence homologies between alpha-endorphin and the amino acid composition of a certain immunoglobulin are responsible for the immunocytochemically specific alpha-endorphin-like immunoreactivity of plasma cells.

Animals↗
PubMed1980

[Immunocytochemical characterization of enteric hormones (author's transl)].

As yet 16 different polypeptide have been found in the gastrointestinal tract. Definite entero-endocrine cell types classified mainly by ultrastructural features were identified--more or less reliable--as the cellular sources of certain enteric hormones. Concerning the immunocytochemical characterization of enteric hormones and the identification of entero-endocrine cells responsible for the synthesis of enteric hormones, however, several peculiarities have to be taken into consideration. These included similarities certain enteric hormones on the one hand and similarities in the ultrastructure of entero-endocrine cell type on the other as well as peculiarities with respect to immunoreactivities of entero-endocrine cells (e.g. the ability of certain entero-endocrine cell types to bind immunoglobulins unspecifically). Apart from the immunocytochemical identification of entero-endocrine cells at the ultrastructural level further investigations in this field should deal with the immunocytochemical localization of hormone precursor substances. Thus the multitude of enteric hormones and entero-endocrine cell types may be reduced to some "basic" types. Finally, investigations on enteric polypeptide hormones seem to be a wider interest in biology and medicine since some of these hormones are also located in the central and peripheral nervous system. These peptides may represent a system of chemical messengers utilized in the body as hormones, neurotransmitters and paracrine (i.e. local acting) substances.

Animals↗