An immunocytochemical study of endocrine pancreas of snakes

Targeted nutritional intervention with enhanced recovery after surgery for carotid endarterectomy: A prospective clinical trial

Ischemic stroke is the most common cerebrovascular disease, and vascular obstruction is an important cause of this disease. As the main method for the management of carotid artery stenosis, carotid endarterectomy (CEA) is an effective and preventive treatment measure in ischemic cerebrovascular disease. This study aims to propose the application of a new enhanced recovery after surgery (ERAS) nutritional support regimen in CEA, which can significantly improve the perioperative nutritional status of patients. A total of 74 patients who underwent CEA were included and randomly divided into two groups: 39 patients received nutritional therapy with the ERAS protocol (ERAS group) and 35 patients received routine perioperative nutritional support (control group). Our results showed that the levels of major clinical and biochemical parameters (albumin, hemoglobin, creatinine, calcium and magnesium levels, etc.) in the ERAS group were significantly higher than those in the control group after surgery (p < 0.05). Additionally, patients in the ERAS group had dramatically shorter postoperative length of stay and reflected higher mean satisfaction at discharge (p < 0.001). Moreover, no statistically significant differences were observed in postoperative complication rates and Mini-mental State Examination scores at discharge. The emergence of this neurosurgical ERAS nutritional support program can effectively intervene in perioperative nutritional status, and notably reduce postoperative hospital stays.

Architecture of the Pancreatic Islets and Endocrine Cell Arrangement in the Embryonic Pancreas of the Grass Snake (Natrix natrix L.). Immunocytochemical Studies and 3D Reconstructions

During the early developmental stages of grass snakes, within the differentiating pancreas, cords of endocrine cells are formed. They differentiate into agglomerates of large islets flanked throughout subsequent developmental stages by small groups of endocrine cells forming islets. The islets are located within the cephalic part of the dorsal pancreas. At the end of the embryonic period, the pancreatic islet agglomerates branch off, and as a result of their remodeling, surround the splenic "bulb". The stage of pancreatic endocrine ring formation is the first step in formation of intrasplenic islets characteristics for the adult specimens of the grass snake. The arrangement of endocrine cells within islets changes during pancreas differentiation. Initially, the core of islets formed from B and D cells is surrounded by a cluster of A cells. Subsequently, A, B, and D endocrine cells are mixed throughout the islets. Before grass snake hatching, A and B endocrine cells are intermingled within the islets, but D cells are arranged centrally. Moreover, the pancreatic polypeptide (PP) cells are not found within the embryonic pancreas of the grass snake. Variation in the proportions of different cell types, depending on the part of the pancreas, may affect the islet function-a higher proportion of glucagon cells is beneficial for insulin secretion.

A comparative immunohistochemical study of pancreatic islets in laboratory animals (rats, dogs, minipigs, nonhuman primates)

The aim of the present study was to distinguish and describe the patterns of distribution of pancreatic islets within the pancreas of four species of laboratory animals, including rats, dogs, minipigs and monkeys, and furthermore, to identify immunohistochemically various islet cell types and characterize their content. Histopathological examinations were performed on sections stained with hematoxylin and eosin (H&E) and immunostained using rabbit polyclonal antibodies (pAb) against insulin, glucagon, pancreatic polypeptide (PP), somatostatin, chromogranin A, keratin, bombesin and gastrin, or mouse monoclonal antibodies (mAb) against synaptophysin, Leu-7 and proliferating cell nuclear antigen (PCNA) in three-step rabbit immunoperoxidase (PAP) and streptavidin/peroxidase (StreptABC/HRP) reactions. Positive immunohistochemical reactions were observed in the pancreatic islets of all animal species with all antibodies, except with anti-bombesin and anti-gastrin antibodies. Our results revealed that: 1) there is species specific regional arrangement of islets in the pancreas, 2) each species presents a characteristic distribution of cells producing different hormones. 3) immunoreactivity with immunohistochemical markers varies between species and/or age. The present comparative immunohistochemical study could be helpful for answering questions which are important for understanding some of the intricate mechanisms that govern the integrated function of the endocrine pancreas.

Purification and characterization of islet hormones (insulin, glucagon, pancreatic, polypeptide and somatostatin) from the Burmese python, Python molurus

Insulin was purified from an extract of the pancreas of the Burmese python, Python molurus (Squamata:Serpentes) and its primary structure established as: A Chain: Gly-Ile-Val-Glu-Gln-Cys-Cys-Glu-Asn-Thr10-Cys-Ser-Leu-Tyr-Glu-Leu- Glu-Asn-Tyr-Cys20-Asn. B-Chain: Ala-Pro-Asn-Gln-His-Leu-Cys-Gly-Ser-His10-Leu-Val-Glu-Ala-Leu-Tyr- Leu-Val-Cys-Gly20-Asp-Arg-Gly-Phe-Tyr-Tyr-Ser-Pro-Arg-Ser30. With the exception of the conservative substitution Phe --> Tyr at position B25, those residues in human insulin that comprise the receptor-binding and those residues involved in dimer and hexamer formation are fully conserved in python insulin. Python insulin was slightly more potent (1.8-fold) than human insulin in inhibiting the binding of [125I-Tyr-A14] insulin to the soluble full-length recombinant human insulin receptor but was slightly less potent (1.5-fold) than human insulin for inhibiting binding to the secreted extracellular domain of the receptor. The primary structure of python glucagon contains only one amino acid substitution (Ser28 --> Asn) compared with turtle/duck glucagon and python somatostatin is identical to that of mammalian somatostatin-14. In contrast, python pancreatic polypeptide (Arg-Ile-Ala-Pro-Val-Phe-Pro-Gly-Lys-Asp10-Glu-Leu-Ala-Lys-Phe- Tyr20-Thr-Glu-Leu-Gln-Gln-Tyr-Leu-Asn-Ser-Ile30-Asn-Arg-Pro-Arg -Phe.NH2) contains only 35 instead of the customary 36 residues and the amino acid sequence of this peptide has been poorly conserved between reptiles and birds (18 substitutions compared with alligator and 20 substitutions compared with chicken).

An immunocytochemical study of the endocrine pancreas in three genera of lacertids

The comparative morphology of the endocrine pancreas was studied in 11 species of lacertids. Four major cell types were identified immunocytochemically in the endocrine pancreas: glucagon-immunoreactive A-cells, insulin-immunoreactive B-cells, somatostatin-(SRIF)-immunoreactive D-cells, and pancreatic polypeptide(PP)-immunoreactive F-cells. Different distributions of the four cell types were seen in the endocrine tissue within the exocrine parenchyma. F-cells were rare or absent in the splenic lobe and abundant in the duodenal lobe, in which they were usually widespread in the exocrine parenchyma and rarer in the islets. The other three cell types were always present in the islets. The central core consisted of B- and A-cells, with B-cells predominating. The peripheral mantle was formed by A-cells and less abundant D-cells. Rare D-cells were also found in the central core. D- and F-cells showed projections often closely associated with capillaries. The observed arrangements in islets and isolated cells may represent an endocrine network that, in addition to systemic actions, may regulate exocrine function in a paracrine fashion.

Anatomy of the pancreas and Langerhans islets in snakes and lizards

The pancreas of snakes (18 species) was comparatively examined and classified into five major types, based on structure of the lobes and ducts, spatial relationships with the spleen and the gall bladder, and the disposition of islet cells. These types trend toward fusion of the pancreatic lobes and compaction of the pancreas--a progression that coincides with the phylogeny of the snakes. The more primitive pancreas of lizards (17 species) also was surveyed; that of Varanus is of special interest because its structure is intermediate between the extended, tri-lobate pancreas of lizards and the compact pancreas of snakes and may represent a transitional link in the evolution of this organ. Islet tissue is always confined to the dorsal lobe and is concentrated in its distal region adjacent to the spleen. In primitive snakes and in Varanus, a large islet mass is sequestered within a distinct juxtasplenic "islet body" distanced from the dorsal lobe and connected to it by a slender stalk. In some of the most advanced snake species, numerous islets of endocrine cells are found within the spleen. The occurrence and formation of these intrasplenic islets is described in detail. The anatomic "affinity" between spleen and the islet region of the pancreas is discussed. A hypothesis for the development of the pancreas from embryonal placodes on the mid-gut is presented; it proposes that the exocrine and the endocrine components derive from different progenitor cells, and that the endocrine progenitors are located in the center of the dorsal placode. The hypothesis combines embryological and evolutionary views about the origin of the pancreas, and offers a rationale for differences in its structure and in the disposition of the islets.

Isolation and structural characterization of insulin, glucagon and somatostatin from the turtle, Pseudemys scripta

The chelonians occupy an important position in phylogeny representing a very early branching from the ancestral reptile stock. Hormonal polypeptides in an extract of the pancreas of the red-eared turtle were purified to homogeneity by reversed phase HPLC and their primary structures were determined. Turtle insulin is identical to chicken insulin. Turtle glucagon differs from chicken glucagon by the substitution of a serine by a threonine residue at position 16 and from mammalian glucagon by an additional substitution of an asparagine by a serine residue at position 28. Turtle pancreatic somatostatin is identical to mammalian somatostatin-14. The crocodilians are phylogenetically much closer to the birds than are the chelonians. Alligator insulin, however, contains three amino acid substitutions relative to chicken insulin. Thus, caution is required when inferring phylogenetic relationships based upon a comparison of amino acid sequences of homologous peptides.

Comparative immunohistochemical study of the gastroenteropancreatic endocrine system of three reptiles

The gastroenteropancreatic (GEP) endocrine system of three reptiles, Testudo graeca, Mauremys caspica, and Lacerta lepida, was investigated by means of immunocytochemistry. Single and double immunostaining methods have demonstrated immunoreactivity for insulin, glucagon, pancreatic polypeptide (PP), somatostatin, serotonin, and peptide tyrosine tyrosine (PYY) in endocrine cells of the pancreas of the reptiles studied. Islet-like structures with insulin-immunoreactive (IR) cells surrounded by glucagon-IR cells were observed only in the splenic portion of the pancreas of M. caspica. Occasionally, somatostatin- and PP-IR cells were associated with glucagon-containing cells. Endocrine cells were also observed in the excretory ducts of the exocrine glands. Serotonin, bombesin, neurotensin, gastrin, glucagon, somatostatin, PYY, and insulin were demonstrated immunocytochemically in open-type GEP cells of the digestive tract of the animals studied. Serotonin, somatostatin, and glucagon-immunoreactive cells were the most abundant endocrine cell types. In L. lepida, PP- and peptide tyrosine tyrosine-immunoreactive cells were also frequently observed. Cells containing cholecystokinin, gastric inhibitory peptide, met- and leu-enkephalin, motilin, secretin, and vasoactive intestinal peptide could not be detected. The present work demonstrates that the reptilian GEP endocrine system is a complex structure containing most of the regulatory peptides similar in structure to those found in higher vertebrates.

Histological and immunocytochemical study of the endocrine pancreas of the lizard Podarcis hispanica Steindachner, 1870 (Lacertidae)

The endocrine pancreas of the lizard Podarcis hispanica is described using light and electron microscopy. The endocrine pancreas of this reptile is located throughout the spleen side of the organ and consists of islet-like structures, small groups of two to five cells, and single scattered endocrine cells. The endocrine cells, including the islet-like structures, are not discrete units; on the contrary, they are intermingled with the endocrine component, both forming the glandular units. The endocrine islet-like structure shows a peculiar pseudoacinar pattern. The tridimensional reconstruction allows us to recognize the true structure of the glandular units. They are made up of two or three tubules closely arranged around a blood vessel, the endocrine component being disposed in the facing aspects of the tubules, around the vessel. Silver methods, Giemsa, and peroxidase-antiperoxidase techniques for light microscopy, immunogold, and routine methods for electron microscopy were used to demonstrate the regulatory peptide-producing cells present in the endocrine pancreas. Four major pancreatic endocrine cells, immunolocalized with the light and electron microscope, have been described: glucagon-containing cells (granules of 440 nm in diameter), insulin cells (400 nm), somatostatin cells (610 nm), and pancreatic polypeptide-containing cells (460 nm).

Immunocytochemical localization of peptides in the endocrine pancreas of the snakes Vipera aspis and Natrix maura

The endocrine pancreas of Vipera aspis and Natrix maura has been investigated by immunocytochemistry for the presence of six peptides reported to occur in Mammals or in Reptiles. Gastrin/CCK and PP were absent in the endocrine cells, VIP was located within nerve terminals only. Insulin, Glucagon, and Somatostatin were localized both in Vipera and Natrix, generally with a ring of D (Somatostatin) cells surrounding a core of Glucagon (A) and Insulin (B) producing cells; however frequent clusters of D cells are intermingled with the other endocrine cells. Statistical evaluations on the percentages of these 3 cell types showed preponderance of A cells in Natrix whereas in Vipera no significant difference was found between the number of A and B cells. The D cells showed a uniform distribution in the pancreas of the 2 studied species, in any case with a percentage slightly inferior to those of B cells.

Endocrine pancreas of Testudo graeca L. (Chelonia) in summer and winter: an immunocytochemical and ultrastructural study

Insulin-, glucagon-, somatostatin-, and PP-immunoreactive cells were identified immunocytochemically using antisera raised against mammalian hormones in the pancreas of Testudo graeca in both winter and summer. The endocrine cells were present throughout the gland, forming scarce islets except in the splenic region. The insulin cell islets were larger and more numerous in the splenic region than in the duodenal one. Winter glucagon-immunoreactive cells were found mainly in isolation while the summer ones occurred in groups which showed no immunoreactive central area; in both seasons these cells were more numerous in the splenic region than in the duodenal one. Somatostatin-immunoreactive cells were found isolated or grouped together more frequently in the splenic region in the summer specimens. No PP-immunoreactive cells were found in the splenic region, although they were numerous and isolated in the duodenal zone. Four cell types (B, A, D, and PP cells) were ultrastructurally characterized by the shape, size, and electron density of their respective secretory granules. Certain ultrastructural differences were detected in the summer and winter endocrine pancreatic cells. In summer specimens a fifth cellular type was observed. The presence of B, D, and PP cells among the epithelial pancreatic duct cells may confirm the comparatively primitive organization of the T. graeca endocrine pancreas.

Immunostaining of a cell type in the islets of Langerhans of the monkey Macaca irus by antibodies against S-100 protein

S-100 protein-immunoreactive cells were demonstrated by immunocytochemical procedures in the pancreatic islets of Langerhans in the monkey Macaca irus. By use of antibodies against human S-100 protein or bovine S-100 protein, these cells were observed in all islets in the head and tail portions of the pancreas. Immunostained cells were usually located in the center of the islets or sometimes found in a more widely distributed form, but they were never arranged in a regular concentric fashion. The number of immunoreactive cells varied from one islet to another but it was relatively limited making up only 0.75%-6.3% of all insular cells. With the use of the double-immunoenzymatic procedure for demonstration of the four main endocrine cell types (insulin-, glucagon-, somatostatin- and pancreatic polypeptide producing elements), it was possible to establish that S-100 protein-immunoreactive cells represent a distinct cell type. Antibodies against S-100 protein-stained neuroinsular complexes. The present findings speak in favor of a new cell type to be added to the large variety of S-100 protein-immunoreactive cells outside the central nervous system.