| 21. |
- Degerman, Eva, et al.
(författare)
-
Expression of insulin signalling components in the sensory epithelium of the human saccule.
- 2013
-
Ingår i: Cell and Tissue Research. - : Springer Science and Business Media LLC. - 1432-0878 .- 0302-766X. ; 352:3, s. 469-478
-
Tidskriftsartikel (refereegranskat)abstract
- Several studies have demonstrated a link between diabetes and the dysfunction of the inner ear. Few studies, however, have reported the signalling mechanisms involved in metabolic control in human inner ear cells. Knowledge of the expression and role of the insulin receptor and downstream signalling components in the inner ear is sparce. Our immunohistochemistry approach has shown that the insulin receptor, insulin receptor substrate 1 (IRS1), protein kinase B (PKB) and insulin-sensitive glucose transporter (GLUT4) are expressed in the sensory epithelium of the human saccule, which also exhibits expression of a calcium-sensitive cAMP/cGMP phosphodiesterase 1C (PDE1C) and the vasopressin type 2 receptor. IRS1 and PDE1C are selectively expressed in sensory epithelial hair cells, whereas the other components are expressed in sensory epithelial supporting cells or in both cell types, as judged from co-expression or non-co-expression with glial fibrillary acidic protein, a marker for supporting cells. Furthermore, IRS1 appears to be localized in association with sensory nerves, whereas GLUT4 is expressed in the peri-nuclear area of stromal cells, as is the case for aquaporin 2. Thus, the insulin receptor, insulin signalling components and selected cAMP signalling components are expressed in the human saccule. In addition to well-known mechanisms of diabetes complications, such as neuropathy and vascular lesions, the expression of these proteins in the saccule could have a role in the observed link between diabetes and balance/hearing disorders.
|
|
| 22. |
- Dircksen, Heinrich, 1954-, et al.
(författare)
-
Crustacean Cardioactive Peptide-immunoreactive neurons innervating brain neuropils, retrocerebral complex and stomatogastric nervous-system of the locust, Locusta migratoria
- 1995
-
Ingår i: Cell and Tissue Research. - 0302-766X .- 1432-0878. ; 279, s. 495-515
-
Tidskriftsartikel (refereegranskat)abstract
- The distribution and morphology of crustacean cardioactive peptide-immunoreactive neurons in the brain of the locust Locusta migratoria has been determined. Of more than 500 immunoreactive neurons in total, about 380 are interneurons in the optic lobes. These neurons invade several layers of the medulla and distal parts of the lobula. In addition, a small group of neurons projects into the accessory medulla, the lamina, and to several areas in the median protocerebrum. In the midbrain, 12 groups or individual neurons have been reconstructed. Four groups innervate areas of the superior lateral and ventral lateral protocerebrum and the lateral horn. Two cell groups have bilateral arborizations anterior and posterior to the central body or in the superior median protocerebrum. Ramifications in subunits of the central body and in the lateral and the median accessory lobes arise from four additional cell groups. Two local interneurons innervate the antennal lobe. A tritocerebral cell projects contralaterally into the frontal ganglion and appears to give rise to fibers in the recurrent nerve, and in the hypocerebral and ingluvial ganglia. Varicose fibers in the nervi corporis cardiaci III and the corpora cardiaca, and terminals on pharyngeal dilator muscles arise from two subesophageal neurons. Some of the locust neurons closely resemble immunopositive neurons in a beetle and a moth. Our results suggest that the peptide may be (1) a modulatory substance produced by many brain interneurons, and (2) a neurohormone released from subesophageal neurosecretory cells.
|
|
| 23. |
- Dircksen, Heinrich, 1954-, et al.
(författare)
-
Crustacean cardioactive peptide in the nervous system of the locust, Locusta migratoria: an immunocytochemical study on the ventral nerve cord and peripheral innervation
- 1991
-
Ingår i: Cell and Tissue Research. - Heidelberg New York : Springer. - 0302-766X .- 1432-0878. ; 263, s. 439-457
-
Tidskriftsartikel (refereegranskat)abstract
- Crustacean cardioactive peptide-immunoreactive neurons occur in the entire central nervous system of Locusta migratoria. The present paper focuses on mapping studies in the ventral nerve cord and on peripheral projection sites. Two types of contralaterally projecting neurons occur in all neuromers from the subesophageal to the seventh abdominal ganglia. One type forms terminals at the surface of the thoracic nerves 6 and 1, the distal perisympathetic organs, the lateral heart nerves, and on ventral and dorsal diaphragm muscles. Two large neurons in the anterior part and several neurons of a different type in the posterior part of the terminal ganglion project into the last tergal nerves. In the abdominal neuromers 1–7, two types of ipsilaterally projecting neurons occur, one of which gives rise to neurosecretory terminals in the distal perisympathetic organs, in peripheral areas of the transverse, stigmata and lateral heart nerves. Four subesophageal neurons have putative terminals in the neurilemma of the nervus corporis allati II, and in the corpora allata and cardiaca. In addition, several immunoreactive putative interneurons and other neurons were mapped in the ventral nerve cord. A new in situ whole-mount technique was essential for elucidation of the peripheral pathways and targets of the identified neurons, which suggest a role of the peptide in the control of heartbeat, abdominal ventilatory and visceral muscle activity.
|
|
| 24. |
- Dircksen, Heinrich, 1954-
(författare)
-
Fine structure of the neurohemal sinus gland of the shore crab, Carcinus maenas, and immuno-electron-microscopic identification of neurosecretory endings according to their neuropeptide contents
- 1992
-
Ingår i: Cell and Tissue Research. - 0302-766X .- 1432-0878. ; 269:2, s. 249-266
-
Tidskriftsartikel (refereegranskat)abstract
- The sinus gland of the shore crab, Carcinus maenas, is a compact assembly of interdigitating neurosecretory axon endings abutting upon the thin basal lamina of a central hemolymph lacuna. Four types of axon endings are distinguishable by the size distribution, shape, electron density and core structure of their neurosecretory granules. One additional type of axon ending is characterized by electron-lucent vacuoles and vesicles. The axon profiles are surrounded by astrocyte-like glial cells. Various fixations followed by epoxy- or Lowicryl-embedding were compared in order to optimize the preservation of the fine structure of the granule types and the antigenicity of their peptide hormone contents. By use of specific rabbit antisera, the crustacean hyperglycemic, molt-inhibiting, pigment-dispersing, and red-pigment-concentrating hormones were assigned to the four distinct granule types which showed no overlap of immunostaining. Epi-polarization microscopy and ultrathin section analysis of immunogold-stained Lowicryl-embedded specimens revealed that immunoreactivity to Leu-enkephalin and proctolin is co-localized with molt-inhibiting hormone immunoreactivity in the same type of granule. The size and core structure of the immunocytochemically identified granule types vary little with the different pretreatments but, in some cases, to a statistically significant extent. The present results are compared with those from earlier studies of sinus glands in different crustaceans. The methods of granule identification used in this study supplement the classical approach in granule typing; they are easier to perform and more reliable for the analysis of release phenomena in identified secretory neurons supplying the neurohemal sinus gland.
|
|
| 25. |
- Dircksen, Heinrich, 1954-, et al.
(författare)
-
Immunocytochemical demonstration of the neurosecretory systems containing putative moult-inhibiting hormone and hyperglycemic hormone in the eyestalk of brachyuran crustaceans
- 1988
-
Ingår i: Cell and Tissue Research. - 0302-766X .- 1432-0878. ; 251, s. 3-12
-
Tidskriftsartikel (refereegranskat)abstract
- By use of antisera raised against purified moultinhibiting (MIH) and crustacean hyperglycemic hormone (CHH) from Carcinus maenas, complete and distinct neurosecretory pathways for both hormones were demonstrated with the PAP and immunofluorescence technique. By double staining, employing a combination of silver-enhanced immunogold labelling and PAP, both antigens could be visualized in the same section. Immunoreactive structures were studied in Carcinus maenas, Liocarcinus puber, Cancer pagurus, Uca pugilator and Maja squinado. They were only observed in the X-organ sinus gland (SG) system of the eyestalks and consisted of MIH-positive perikarya, which were dispersed among the more numerous CHH-positive perikarya of the medulla terminalis X-organ (XO). The MIH-positive neurons form branching collateral plexuses adjacent to the XO and axons that are arranged around the CHH-positive central axon bundle of the principal XO-SG tract. In the SG, MIH-positive axon profiles and terminals, clustered around hemolymph lacunae, are distributed between the more abundant CHH-positive axon profiles and terminals. Colocalisation of MIH and CHH was never observed. The gross morphology of both neurosecretory systems was similar in all species examined, however, in U. pugilator and M. squinado immunostaining for MIH was relatively faint unless higher concentrations of antiserum were used. Possible reasons for this phenomenon as well as observed moult cycle-related differences in immunostaining are discussed.
|
|
| 26. |
- Dircksen, Heinrich, 1954-, et al.
(författare)
-
Immunocytochemical localization of CCAP, a novel crustacean cardioactive peptide, in the nervous system of the shore crab, Carcinus maenas L.
- 1988
-
Ingår i: Cell and Tissue Research. - 0302-766X .- 1432-0878. ; 254:2, s. 347-360
-
Tidskriftsartikel (refereegranskat)abstract
- Polyclonal antibodies were raised in rabbits against synthetic crustacean cardioactive peptide (CCAP) conjugated to bovine thyroglobulin, and were used to map CCAP-immunoreactive structures in the central nervous system of Carcinus maenas. As expected, the neurohemal pericardial organs (PO) displayed abundant immunoreactivity in nerve fibers and terminals. In addition, immunoreactive neurons were demonstrated in other parts of the nervous system. At least some of them do not appear to terminate in neurohemal structures and may have a non-endocrine, as yet unknown function. Immunoreactive perikarya with a diameter of 25–30 m occur in the brain. They project into the optic and antennary neuropil, and into the eyestalk. One cell was found in the medulla terminalis of the eyestalk and in the connective ganglion, respectively. From the latter, axonal branches could be traced into the brain and the thoracic ganglia (TG). In the TG, small-diameter perikarya give rise to extensive networks of varicose fibers. Some of the perikarya occur in a characteristic paired arrangement with larger CCAP-immunoreactive somata (diameter 40–50 m). These pairs of one small and one large cell occur in all mouthpart and leg segments of the TG, except the abdominal ganglia (AG), where only large cells were found. The main projections of the large neurons comprise one or more fibers in each of the seven segmental nerves (SN), leading to neurosecretory terminals in the PO. The fibers in the SN are joined by branches of an ascending axonal tract from the large perikarya in the AG. The large-type perikarya are considered to be the principal source of CCAP in the PO. The optic ganglia in the eyestalk, except the medulla terminalis, the neurohemal sinus gland and the stomatogastric nervous system are devoid of CCAP-immunoreactivity.In axon terminals of the PO, CCAP is not colocalized with other PO-neuropeptides, i.e. proctolin-, FMRFamide-like, and Leu-enkephalin-like immunoreactive materials. Electron-microscopic immunocytochemistry revealed a distinct CCAP-containing granule type in specific axon profiles and terminals in the PO.The architecture of CCAP-immunoreactive neurons is discussed with respect to previous morphological studies on the origin and pathways of fibers terminating in the PO.
|
|
| 27. |
- Dircksen, Heinrich, 1954-, et al.
(författare)
-
The ultrastructure of nerve endings containing pigment-dispersing hormone (PDH) in crustacean sinus glands: Identification by an antiserum against a synthetic PDH
- 1987
-
Ingår i: Cell and Tissue Research. - : Springer. - 0302-766X .- 1432-0878. ; 250:2, s. 377-387
-
Tidskriftsartikel (refereegranskat)abstract
- A high-liter antiserum has been obtained from two rabbits immunized with a glutaraldehyde conjugate of synthetic pigment-dispersing hormone (PDH) from Uca pugilator and bovine thyroglobulin. The antiserum blocked melanophore-dispersing activity of the peptide in vivo. In sinus glands (SG) of Carcinus maenas, Cancer pagurus, Uca pugilator and Orconectes limosus, electron-microscopic immunocytochemistry revealed sparsely distributed axon endings containing a distinct PDH-immunoreactive type of neurosecretory granules (diameter 90–130 nm). Exocytotic figures indicating release of the content of these granules into hemolymph lacunae were occasionally observed. Preservation of fine structure and antigenicity of the PDH granules were markedly dependent on the fixation procedure used. A preliminary experiment with C. maenas showed that preterminal axon dilatations near the basal lamina seemed to accumulate PDH-granules when animals were kept in complete darkness for three days. Immunodot blotting of fractions after high pressure liquid chromatography (HPLC) of extracts from SGs of C. maenas and O. limosus revealed a strongly immunoreactive substance at a retention time very similar to those of synthetic PDHs of Uca pugilator and Pandalus borealis. It is also coincident with a zone of biological activity. Thus, the antigen demonstrated by immunocytochemistry is identical or very similar to one of the known PDHs.
|
|
| 28. |
- Durbeej-Hjalt, Madeleine
(författare)
-
Laminins.
- 2010
-
Ingår i: Cell and Tissue Research. - : Springer Science and Business Media LLC. - 1432-0878 .- 0302-766X. ; 339, s. 259-268
-
Tidskriftsartikel (refereegranskat)abstract
- Laminins are cell adhesion molecules that comprise a family of glycoproteins found predominantly in basement membranes, which are the thin sheets of extracellular matrix that underlie epithelial and endothelial cells and surround muscle cells, Schwann cells, and fat cells. Many laminins self-assemble to form networks that remain in close association with cells through interactions with cell surface receptors. Laminins are vital for many physiological functions. They are essential for early embryonic development and organogenesis and have crucial functions in several tissues including muscle, nerve, skin, kidney, lung, and the vasculature. A great wealth of data on laminins is available, and an in-depth description is not attempted here. In this review, I will instead provide a snapshot of laminin structure, tissue distribution, and interactions with other matrix molecules and receptors and briefly describe laminin mutations in mice and humans. Several illuminating and timely reviews are cited that can be consulted for references to original articles and more detailed information concerning laminins.
|
|
| 29. |
- Eckhard, Andreas, et al.
(författare)
-
Co-localisation of Kir4.1 and AQP4 in rat and human cochleae reveals a gap in water channel expression at the transduction sites of endocochlear K+ recycling routes
- 2012
-
Ingår i: Cell and Tissue Research. - : Springer Science and Business Media LLC. - 0302-766X .- 1432-0878. ; 350:1, s. 27-43
-
Tidskriftsartikel (refereegranskat)abstract
- Sensory transduction in the cochlea depends on perilymphatic-endolymphatic potassium (K+) recycling. It has been suggested that the epithelial supporting cells (SCs) of the cochlear duct may form the intracellular K+ recycling pathway. Thus, they must be endowed with molecular mechanisms that facilitate K+ uptake and release, along with concomitant osmotically driven water movements. As yet, no molecules have been described that would allow for volume-equilibrated transepithelial K+ fluxes across the SCs. This study describes the subcellular co-localisation of the Kir4.1 K+ channel (Kir4.1) and the aquaporin-4 water channel (AQP4) in SCs, on the basis of immunohistochemical double-labelling experiments in rat and human cochleae. The results of this study reveal the expression of Kir4.1 in the basal or basolateral membranes of the SCs in the sensory domain of the organ of Corti that are adjacent to hair cells and in the non-sensory domains of the inner and outer sulci that abut large extracellular fluid spaces. The SCs of the inner sulcus (interdental cells, inner sulcus cells) and the outer sulcus (Hensen’s cells, outer sulcus cells) display the co-localisation of Kir4.1 and AQP4 expression. However, the SCs in the sensory domain of the organ of Corti reveal a gap in the expression of AQP4. The outer pillar cell is devoid of both Kir4.1 and AQP4. The subcellular co-localisation of Kir4.1 and AQP4 in the SCs of the cochlea described in this study resembles that of the astroglia of the central nervous system and the glial Mueller cells in the retina.
|
|
| 30. |
- Edman, Anne-Christine, et al.
(författare)
-
Structural diversity in muscle fibres of chicken breast
- 1988
-
Ingår i: Cell and Tissue Research. - 0302-766X .- 1432-0878. ; 251:2, s. 281-289
-
Tidskriftsartikel (refereegranskat)abstract
- hicken breast muscle is usually considered to be a relatively homogeneous white muscle and has therefore been widely used for studies of muscle proteins. In a previous study, however, we have found different M-region structures in different fibres from this muscle. Because of this result, we have now carried out a combined histochemical and ultrastructural survey of this muscle. In particular, we have made use of large transverse cryo-sections that include most of the muscle cross-section. Although the white region is fairly homogeneous in fibre content according to normal histochemical criteria (mATPase), we have found that there is a gradation of fibre structure across the muscle. The bulk of the muscle stains conventionally for Type-II fibres according to mATPase tests (the "white" part) but, in the small "red" part of the muscle, there are also Type-I fibres together with the Type-II fibres. Superimposed on this division into Type-I and Type-II fibres are variations in fibre size, oxidative and glycolytic staining properties, and variations of Z-band width and M-band structure; there is no strict correlation among any of these parameters. The apparently uniform staining across most of the muscle when tested for myofibrillar ATPase may be a misleading indicator of fibre properties.
|
|
