Biomedical subjects

K Qvortrup

Publications and source records attributed to K Qvortrup.

At least 19 recordsLinked to original sources

PubMed2002

Collagen fibril size and crimp morphology in ruptured and intact Achilles tendons.

The present study examined the hypothesis that collagen fibril diameter and crimp angle in ruptured human Achilles tendons differed from that of intact ones. Tissue samples were obtained from the central core (distal core) and the posterior periphery (distal superficial) at the rupture site, and the proximally intact (proximal superficial) part of the tendon in 10 subjects (38+/-8 years) with a complete tendon rupture. For comparisons corresponding tissue samples were procured from age (38+/-7 years) and gender matched intact Achilles tendons during routine forensic autopsy. The cross-sectional area density and diameter distribution of fibrils were analyzed using stereological techniques of digitized electron microscopy biopsy cross-sections, while crimp angle was measured by the changing banding pattern of collagen fibers when rotated between crossed polars. Nine of 10 persons with tendon ruptures reported that the injury did not occur during exceedingly large forces, and none experienced any symptoms in the days or months prior to the injury. Fibril diameter distribution showed no region-specific differences in either the ruptured or intact tendons for either group. However, in the distal core there were fewer fibrils in the ruptured compared to the intact tendons in 60-150 nm range, P<0.01. Similarly, in the distal superficial portion there were fewer fibrils in the ruptured compared to the intact tendons in the 90-120 nm range, 2P<0.05, while there were no differences in the proximal superficial tendons. Crimp angle did not display any region-specific differences, or any difference between the rupture and intact tendons. In conclusion, these data suggest that although crimp morphology is unchanged there appears to be a site-specific loss of larger fibrils in the core and periphery of the Achilles tendon rupture site. Moreover, the lack of symptoms prior to the rupture suggests that clinical tendinopathy is not an etiological factor in complete tendon ruptures.

Achilles Tendon↗

PubMed2001

Bronchial transsection and reanastomosis in pigs with and without bronchial arterial circulation.

BACKGROUND: The bronchial artery may be vital to the bronchi and lung parenchyma, but results of lung transplantation have raised doubts. This study was performed to examine the effect of bronchial arterial devascularization on bronchial morphology after bronchial transsection and reanastomosis. METHODS: In 6 pigs (study group), the left main bronchus was transsected, reanastomosed, and devascularized. Six control pigs had the same operation without devascularization. After 1 week, bronchial arterial angiography was performed, and specimens were examined with conventional histology and scanning electron microscopy. RESULTS: Histology showed significant changes (inflammation, edema, and fibrosis) in bronchi and lung parenchyma of the study group compared with the unoperated side (p = 0.028) and with the control group (p = 0.050). Scanning electron microscopy showed significant ciliary denudation in the study group's left bronchus compared with the unoperated side (p = 0.043) and with the control group (p = 0.0071). CONCLUSIONS: The loss of cilia of the bronchial epithelium and the occurrence of inflammation, edema, and fibrosis in bronchi and lung parenchyma 1 week postoperatively were significantly related to the absence of the bronchial arterial circulation.

Anastomosis, Surgical↗

PubMed2001

Bronchial arterial devascularization. An experimental study in pigs.

OBJECTIVE: The lungs have dual blood supply: The bronchial and the pulmonary circulation. The importance of bronchial circulation is disputed. The purpose of this study was to establish an experimental model to examine the importance of the bronchial artery. DESIGN: Comparative porcine experimental study. The surgical technique was evaluated in group A (n = 9). Group B (n = 8) underwent left bronchial arterial devascularization. In group C (n = 9) the left principal bronchus was devascularized, transsected, and reanastomosed. In groups B and C bronchial mucosal blood flow was studied with laser-Doppler velocimetry. Devascularization was controlled by angiography at section, and specimens were examined with conventional histology and scanning electron microscopy. The right bronchus served as control. RESULTS: In group B devascularization caused considerable, yet insignificant reduction in bronchial mucosal blood flow index (p = 0.1282) postoperatively, and after 1 week (p = 0.0678), insignificant histologic (p > 0.2) changes, and no scanning electron microscopy differences. In group C devascularization with bronchial transsection caused significant reduction in mucosal blood flow index (p = 0.0277) postoperatively and after 1 week (p = 0.0277), significant histologic changes (p = 0.0277), and insignificant (p = 0.069) changes in scanning electron microscopy. CONCLUSION: Bronchial arterial devascularization with transsection caused significant physiologic and morphologic changes, and a model with bronchial devascularization should include transsection.

Angiography↗

PubMed2000

The superficial anulus fibrosus ligament. An incipient description of a separate ligament between the lumbar anterior longitudinal ligament and the intervertebral disc.

A previously unknown ligament, the superficial anulus fibrosus ligament (SAFL), situated on the ventral part of the L5 intervertebral disc (ID) was observed and described from autopsy material. Twenty-eight cadaveric specimens from 12 black and 16 white persons aged 17-30 years were studied during routine forensic autopsies. The anterior longitudinal ligament was separated from the ID and the ventral part of the SAFL was visualized. The SAFL samples were removed, measured and studied with both conventional histology and examination by transmission electron microscopy. The SAFL was a completely separate ligament at the level of the L5-S1 ID situated between the anterior longitudinal ligament and the anulus fibrosus of the ID. The fibers of the ligament were vertically oriented. A difference in distance between the L5-S1 vertebral bodies ventrally was noted in the two groups studied (18.7 +/- 1.2 mm in the black vs. 15.2 +/- 1.0 mm in the white, p < 0.001), indicating a difference in the ventral thickness of the intervertebral disc. Also, there was a difference in the length (black: 17.7 +/- 1.6 mm vs. white: 14.1 +/- 1.1), thickness (black: 3.3 +/- 0.3 mm vs. white: 2.1 +/- 1.9), and the cross-sectional area (black: 58.2 +/- 6.7 mm(2) vs. white: 26.5 +/- 2.7 mm(2), p < 0.001) of the SAFL. Conventional light microscopy revealed no obvious differences. However, transmission electron microscopy revealed notably larger collagen fibril diameter in black than white subjects. In conclusion, the interbody distances were greater in the black group, indicating a greater intervertebral disc thickness, compared to that of the white. Furthermore, the SAFL was significantly longer and thicker in the black than in the white group. Albeit unsubstantiated, these race-specific macroscopic findings may have implications for understanding the etiology of various low back stress problems.

Adolescent↗

PubMed1999

A note about retinal structure and visual acuity. A light microscopic study of the cones in fovea centralis.

PURPOSE: Production of reliable sections of fovea centralis of primate retina. METHODS: Rhesus monkey eyes were processed using a new technique known to minimize artefacts and cell-shrinkage in other tissues. An in vivo vascular perfusion-fixation technique with an isotonic fixative followed by a process of slow infiltration with small increments in concentrations were used. RESULTS: Tangential 1 microm thick serial-sections showed a very good morphology. An average cone-to-cone-center distance of 3.8 microm in the central part of the fovea centralis was found. A cone-to-cone-center distance of 2.2-2.6 microm is suggested in the literature. CONCLUSION: In spite of the limited study we believe that the new technique has resulted in less tissue shrinkage. Our results are discussed in relation to maximal possible resolution of the eye. Our calculations (for green light) support the idea that the structure of the fovea centralis and the refractive media of the eye are developed close to perfection.

Animals↗

PubMed1999

The endolymphatic sac, a potential endocrine gland?

A previous investigation indicated that the chief cells of the endolymphatic sac produce an endogenous inhibitor of sodium re-absorption in the kidneys, which has tentatively been named "saccin". In this study, the ultrastructure of the endolymphatic sac and in particular the chief cells is described, demonstrating that this organ fulfils the morphological criteria of a potential endocrine gland. Accordingly, the chief cells are shown to exhibit all the organelles and characteristics of cells that simultaneously synthesize, secrete, absorb and digest proteins.

Animals↗

PubMed1999

Ion transport in epithelial spheroids derived from human airway cells.

In the present study, we describe a novel three-dimensional airway epithelial explant preparation and demonstrate its use for ion transport studies by electrophysiological technique. Suspension cultures of sheets of epithelial cells released by protease treatment from cystic fibrosis (CF) and non-CF nasal polyps developed free-floating, monolayered epithelial spheres, with the apical, ciliated cell membrane facing the bath and the basolateral cell membrane pointing toward a fluid-filled lumen. Microelectrode impalement of both non-CF and CF spheroids revealed lumen-positive transepithelial electrical potential differences (PDs) that were inhibited by amiloride, indicating that the spheroids were inflated due to amiloride-sensitive Na+ absorption followed by water. Transformation to a Cl- secretory state was achieved by addition of ATP to the bath, leading to the development of a diphenylamine-2-carboxylate-sensitive PD. A cAMP-induced increase in PD was seen in non-CF spheroids only. In response to hydrocortisone treatment, Na+ transport reflected by amiloride-sensitive PD increased and more so in CF than in non-CF spheres. We concluded that this preparation is a useful model for the airway surface epithelium and is suitable for studies of transport mechanisms and regulation.

Absorption↗

PubMed1999

Fluid absorption related to ion transport in human airway epithelial spheroids.

Airway epithelium explants from cystic fibrosis (CF) patients and non-CF subjects formed monolayered spheres, with the apical ciliated cell membrane facing the bath and the basolateral cell membrane pointing toward a fluid-filled lumen. With the use of two microelectrodes, transepithelial potential difference and changes in potential difference in response to passage of current pulses were recorded, and epithelial resistance and the equivalent short-circuit current were calculated. Non-CF control potential difference and short-circuit current values were significantly lower than the CF values, and amiloride inhibited both values. Fluid transport rates were calculated from repeated measurements of spheroid diameters. The results showed that 1) non-CF and CF spheroids absorbed fluid at identical rates (4.4 microl x cm(-2) x h(-1)), 2) amiloride inhibited fluid absorption to a lower residual level in non-CF than in CF spheroids, 3) Cl(-)-channel inhibitors increased fluid absorption in amiloride-treated non-CF spheroids to a level equal to that of amiloride-treated CF spheroids, 4) hydrochlorothiazide reduced the amiloride-insensitive fluid absorption in both non-CF and CF spheroids, and 5) osmotic water permeabilities were equal in non-CF and CF spheroids ( approximately 27 x 10(-7) cm x s(-1) x atm(-1)).

Amiloride↗

PubMed1999

A polarized light and scanning electron microscopic study of human fissure and lingual enamel of unerupted mandibular third molars.

Using histological and ultrastructural techniques the aims of this study were to investigate whether the mineralization pattern and surface microanatomy of the caries-susceptible fissure enamel were different from those on the caries-inactive lingual surface. The material consisted of 31 unerupted third mandibular molars. The specimens were initially grouped into four categories: (1) without, (2) with initial, (3) with almost completed and (4) with completed root formation. One ground section with fissure-like morphology was selected from each tooth. Using water as a medium the observed birefringence was negative along the lingual and fissure transverses in specimens with almost completed and with completed root formation, while the observed birefringence was positive at different distances in the enamel in sections representing less maturation stages. Qualitative imbibition studies revealed hypomineralized enamel in the lower part of the fissures in specimens representing almost and completed root formation. Imbibed in quinoline, parts of the hypomineralized enamel behaved like a molecular sieve due to the presence of micropores, indicating that the structural arrangement is different from that in the enamel adjacent to this areas. After division of the sections into a lingual and a buccal part, SEM features were described from lower and upper parts of the buccal fissure wall and on lingual enamel in the area corresponding to the bottom part of the fissure. The surface microanatomy varied greatly. Negative developmental irregularities such as fissures and holes were associated with the immature enamel, while matured enamel - particularly fissures - housed many positive developmental irregularities such as enamel caps and protrusions. The crystal size in the mature specimens appeared smaller and more uniform than the crystals from the immature specimens. Apart from the occurrence of hypomineralized enamel in fissures and numerous positive developmental irregularities on the fissure surface, no major differences between fissure and lingual enamel were noticed, neither with respect to mineralization pattern during final stages of tooth development nor to the degree of surface porosity prior to tooth emergence.

Crystallography↗

PubMed1997

Electron microscopic demonstrations of filamentous molecular sieve plugs in capillary fenestrae.

The permeability of capillaries is usually explained with reference to "small pores," permeable to water and small solutes, and "large pores," permeable to proteins. Fenestrated capillaries are far more permeable to water and small solutes than nonfenestrated capillaries; moreover, the permeability is highest in the capillaries with the most fenestrae. This suggests that the small pores reside in the fenestral diaphragms; however, no such pores have been illustrated using electron microscopy. In an attempt to clarify this controversy, fenestrated capillaries in the small intestine, stomach, and kidney of the rat were reinvestigated by electron microscopy. A new method of vascular perfusion-fixation was employed, which included the use of glutaraldehyde dissolved in an oxygen-carrying blood substitute (fluorocarbon) and delivered by a peristaltic pump controlled by pressure feedback. The investigation disclosed a prominent endocapillary surface coat, about 50-100 nm thick, and the existence of bush-like filamentous sieve plugs in the fenestrae. Each filamentous plug was composed of 20-40 filaments, each filament measuring 300-400 nm in length and 5-10 nm in thickness. The filamentous plugs have tentatively been named fascinae fenestrae, because they resemble fascines and may also function as such.

Actin Cytoskeleton↗

PubMed1997

Effect of cyclosporine during initiation of transplant arteriosclerosis. An ultrastructural study in the aorta-transplanted rabbit.

The immunosuppressant cyclosporine protects against the development of experimental transplant arteriosclerosis. To investigate the mechanism underlying this effect, aorta-allografted rabbits were randomly assigned to cyclosporine (n = 6) in the human therapeutic range or to its vehicle (n = 5). Perfusion fixation was performed 2 weeks after the transplantation, followed by light, scanning and transmission electron microscopy examination. Intimal proliferation was absent in native aortas, present in all grafts from vehicle-treated animals, and either absent or sparse in grafts from cyclosporine-treated rabbits. The endothelium of native aortas from both vehicle- and cyclosporine-treated rabbits was normal. Aortic allografts from cyclosporine-treated rabbits exhibited a normal endothelium with only a few adhering mononuclear cells, whereas aortic allografts from vehicle-treated rabbits exhibited an endothelial surface ranging from near-normal with only few adhering platelets and mononuclear cells, to an almost destroyed endothelium, lined with lymphocyte-like cells, monocytes/macrophages, platelets, erythrocytes and fibrin; in the subendothelial layer, mononuclear cells and smooth muscle cells were abundant. These results suggest that damage to the endothelial cells as well as invasion of lymphocytes, monocytes/macrophages and smooth muscle cells into the subendothelial space are important events during initiation of transplant arteriosclerosis, and that cyclosporine largely attenuates these early pathological changes.

Animals↗

PubMed1996

The inner ear produces a natriuretic hormone.

Cytoplasmic granules have been demonstrated in epithelial cells from the endolymphatic sac, an extraosseus part of the inner ear located in the posterior cranial fossa. Intravenously infused extracts from endolymphatic sacs in anesthetized rats elicited a potent natriuresis and diuresis without effects on blood pressure, glomerular filtration rate, or lithium clearance. Only a minor kaliuresis was observed. Extracts of dural tissue adjacent to the endolymphatic sacs had no effect. It is concluded that the endolymphatic sac contains as endogenous inhibitor of sodium reabsorption and could be the sensory organ/mediator of "cerebral" natriuresis. Furthermore, this substance, tentatively named saccin, may influence the homeostasis of the inner ear fluids and accordingly play a significant role in the pathogenesis of Mèniére's disease.

Absorption↗

PubMed1995

Surface morphology of the endolymphatic duct in the rat. A scanning electron microscopy study.

Following intracardiac vascular perfusion fixation of 8 rats with glutaraldehyde in a buffered and oxygenated blood substitute, the vestibular aqueduct and endolymphatic duct were opened by microsurgery of the resulting 16 temporal bones. Optimum preservation of the epithelium for scanning electron microscopy was attained by coating of the specimens with osmium tetroxide and thiocarbohydrazide followed by a continuous dehydration procedure. This technique permitted, for the first time, an investigation of the surface morphology of the epithelial cells in the endolymphatic duct. Three types of cells were identified with the scanning electron microscope. A polygonal and oblong epithelial cell was observed in the largest number throughout the duct, and in the juxtasaccular half of the duct, two additional types of epithelial cells were observed. The scanning electron microscopic observations are compared and discussed with reference to previous transmission electron microscopic studies of the endolymphatic duct.

Animals↗

PubMed1995

Fine structure of the endolymphatic duct in the rat. A scanning and transmission electron microscopy study.

To investigate the surface morphology of the endolymphatic duct epithelium, 8 rats were vascularly perfused with glutaraldehyde in a buffered and oxygenated blood substitute. Optimal preservation of the epithelium for scanning electron microscopy was attained by coating of the specimens with OsO4 and thiocarbohydrazide followed by a continuous dehydration procedure. Three types of cells were identified with the scanning electron microscope: A polygonal and oblong epithelial cell was observed in the largest number throughout the duct, whereas in the juxta-saccular half of the duct two additional types of epithelial cells were observed. The scanning electron microscopical observations are compared and discussed with reference to transmission electron microscopical observations of the endolymphatic duct.

Animals↗

PubMed1995

The suspensory ligament of the endolymphatic duct in the rat. An ultrastructural study.

Following optimized fixation and specimen handling, the endolymphatic duct was investigated by transmission and scanning electron microscopy. Tubular microfibrils, 10-12 nm thick and of indefinite length, occupied the subepithelial compartment abundantly and seemed to insert into the basal lamina of the epithelial cells of the duct and to merge with the bony wall of vestibular aqueduct thus forming a suspensory ligament of the endolymphatic duct. This ligament is suggested to protect the endolymphtaic duct from collapsing and to play a role in the mechanical protection of the vestibular apparatus from sudden increases in intracranial pressure. The capillaries and the aqueductal vein were located in intimate relationship to the epithelial cells. Both types of vessels were provided with fenestrations of the endothelial cells, supporting the proposal that the endolymphatic duct may be involved in the resorption of endolymph.

Animals↗

PubMed1994

Ultrastructure of Reissner's membrane in the rabbit.

The ultrastructure of Reissner's membrane in the rabbit is described following vascular perfusion-fixation of live, anesthetized and artificially respirated healthy animals. A new and improved technique of fixation is employed that includes a pressure feedback controlled peristaltic pump and an oxygen-carrying fixative. In ultrathin sections capillaries were observed between the two cell layers comprising Reissner's membrane. The mesothelial cells facing the scala vestibuli were connected by junctional complexes and neither pores nor discontinuities were observed in the cell layer. In the epithelial cells a well-developed tubulocisternal endoplasmic reticulum (TER) was noted. Computerized three-dimensional reconstruction documented the continuity of this TER, from prominent disc-shaped subsurface cisterns lining the luminal cell membrane to smaller subsurface cisterns lining the abluminal and lateral cell membranes, forming a transcellular canalicular pathway. The possible function of the TER in Reissner's membrane is discussed with reference to endolymph/perilymph homeostasis.

Animals↗

PubMed1994

Ultrastructure of the epithelial cells of the endolymphatic duct in the rat.

The ultrastructure of the epithelial cells of the endolymphatic duct in the rat is described, following vascular perfusion-fixation of live, anaesthetised and artificially respirated animals. The animals were fixed by means of a pressure feed-back controlled peristaltic pump and an isotonic perfusate-fixative containing glutaraldehyde and Dextran. The endolymphatic duct was isolated by microdissection after the perfusion-fixation, to omit the step of a demineralization procedure. The proximal, intermediate and juxta-saccular parts of the endolymphatic duct were embedded, sectioned and studied separately in the electron microscope. Postfixation in a solution containing OsO4 and potassium ferricyanide revealed a well-developed tubulo-cisternal endoplasmic reticulum (TER), not previously described. Serial sectioning and computerized three-dimensional reconstruction demonstrated a continuity of the TER through the cell from subsurface cisterns abutting on the apical cell membrane to subsurface cisterns abutting on the basolateral cell membrane. The TER resembles that found in solute transporting epithelia, e.g., renal proximal tubule, gall bladder, small intestine and choroid plexus. A fluid resorptive capacity of the epithelial cells of the endolymphatic duct is compatible with the fine structure revealed in the present study. Epithelial cells in the juxta-saccular part of the duct display morphological indications of a secretory activity; furthermore, multivesicular bodies were observed in the epithelial cells throughout the endolymphatic duct.

Animals↗

PubMed1993

Ultrastructure of interstitial cells of Cajal in circular muscle of human small intestine.

BACKGROUND: Interstitial cells of Cajal (ICC) may be important regulatory cells in gut muscle layers. This study examined ICC within the circular muscle of human small intestine. METHODS: Surgically resected, uninvolved intestine was studied by light microscopy and electron microscopy. RESULTS: Muscle lamellae were separated by main septa in continuity with submucosa. Smooth muscle cells ran radially in the septa. Two types of ICC were distinguished. One ICC type had abundant intermediate filaments and smooth cisternae and a discontinuous basal lamina. This ICC type was present in the septa and in the outer third of the circular lamellae. The other ICC type had a complete basal lamina and conspicuous caveolae. This ICC type was observed only in the inner third of the circular lamellae. Both ICC types were close to nerves, but only the latter type formed gap junctions with one another and with muscle cells. Junctions between the two ICC types were not observed. CONCLUSIONS: The arrangement suggests that ICC and radially oriented muscle cells participate in electrical and mechanical coordination of the circular muscle layer of human small intestine.

Adult↗