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  • 1
    Electronic Resource
    Electronic Resource
    Using ultrasound transmission velocity to analyse the mechanical properties of teeth after in vitro, in situ, and in vivo irradiation (2000)
    Springer
    Clinical oral investigations 4 (2000), S. 168-172 
    Details
    ISSN: 1436-3771
    Keywords: Key words Ultrasound ; Radiation caries ; Head and neck neoplasm ; Radiotherapy ; Modulus of elasticity ; Enamel ; Dentine ; In vitro ; In vivo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Ultrasound transmission velocity (UTV) in isotropic material as a measure for the modulus of elasticity was correlated to mechanical properties. Changes in micromechanical properties of radiated teeth and influence of the oral cavity were to be evaluated nondestructively. UTV was measured in extracted teeth after 36 Gy and 62 Gy of in situ (enorally, with no contact to the oral cavity) and in vitro irradiation. Relative to controls, teeth subjected to 62 Gy in vivo showed higher UTV values for dentine and enamel. Sound teeth irradiated with 60 Gy in situ also showed higher UTV values for enamel, whereas dentine values were not significantly different from those of control. The mechanical properties of teeth irradiated in vitro were affected only after high experimental doses of up to 500 Gy. The difference between in vivo and in vitro mechanical properties may be due to radioxerostomia-induced damages as well as the status of dentine vitality. This supports the concept of direct radiation-induced damage in synergy with radioxerostomia-induced caries.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007840000068
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  • 2
    Electronic Resource
    Electronic Resource
    Age-dependence of bone material quality shown by the measurement of frequency of resonance in the ulna (1994)
    Springer
    Calcified tissue international 54 (1994), S. 96-100 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Material quality ; Sound transmission ; Frequency of resonance ; Age ; Bone width
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract In women before and after the age of peak bone mass, identical values of bone mineral density (BMD) can be obtained. However, there is a much higher incidence of osteoporotic fractures in older women. We investigated whether a deterioration of bone material quality with increasing age might contribute to this phenomenon. Material properties of bone tissue can be characterized by the modulus of elasticity, which is correlated to the square of sound transmission velocity. In this study, sound transmission velocity was determined in cortical bone by measuring the frequency of resonance in the ulna in the direction of the bone's longitudinal axis and correcting the values by multiplying by ulna length. Validation of this method indicated acceptable reproducibility: interobserver variability determined as the mean coefficient of variation was 1.82%. In a clinical study, 21 young women (22.5±1.2 years old) were compared with 21 middle-aged women (52.9±2.7 years old). Pairs were matched that had identical values of BMD in the nondominant forearm at a location representing mainly cortical bone (SPA). The product of ulna length and frequency of resonance in the ulna in the younger women was found to be 61.4±5.8 m/second, and in the middle-aged women 55.7±4.5 m/second. The difference was highly significant with P〈0.005. Our results confirm recent findings indicating a deterioration of bone material quality independent of BMD with increasing age. As shown by comparing ulna width at the site of measurement of bone mineral density between both groups of women, the deterioration of bone material quality in ulnar cortical bone with increasing age might at least in part be functionally compensated by an increase of the moment of inertia due to greater bone width [8, 10].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296058
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  • 3
    Electronic Resource
    Electronic Resource
    Confocal Laser Scanning Microscopy: A Nondestructive Subsurface Histotomography of Healthy Human Bone (1999)
    Springer
    Calcified tissue international 65 (1999), S. 8-10 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Microscopy — Confocal methods — Bone — Human — Osteocytes.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. Microscopy of bony tissue usually requires special treatment for decalcification and processing of thin sections. Confocal laser scanning microscopy (CLSM) allows the nondestructive histotomography of organic hard tissue. The aim of this study was to visualize healthy human bone structures and to correlate identical areas in CLSM and conventional light microscopy. Each sample of healthy human lower jaw (n = 20) was divided into three parts: (1) fresh, untreated bony blocks studied by CLSM; (2) MMA-embedded thin sections (without decalcification), HE stained and studied by CLSM and conventional light microscopy (correlation of identical areas); (3) decalcificated, HE stained, histological sections studied by conventional light microscopy. In untreated bony blocks, microstructures such as osteocytes and lamellae were identified by CLSM. These structures could be correlated with conventional light microscopy. In CLSM, subcellular structures cannot yet be interpreted, whereas cytoplastic processes of osteocytes were seen with high contrast. With CLSM, nondestructive histology of cortical bone can be obtained. The risk of artifacts due to pretreatment is minimized, and subsurface visualization does not affect the interpretation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900650
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  • 4
    Electronic Resource
    Electronic Resource
    Different muscarinic receptors mediate autoinhibition of acetylcholine release and vagally-induced vasoconstriction in the rat isolated perfused heart (1990)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 341 (1990), S. 279-287 
    Details
    ISSN: 1432-1912
    Keywords: Prejunctional muscarinic receptors ; Acetylcholine release ; Parasympathetic vasoconstriction ; Methoctramine ; AF-DX 116
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Experiments were carried out on rat isolated perfused hearts with both vagus nerves attached. The acetylcholine stores were labelled with [14C]-choline. The effects of muscarinic receptor antagonists on the [14C]overflow and increase in perfusion pressure evoked by vagus nerve stimulation (10 Hz, 4–10 mA) were studied in order to determine the muscarinic receptor type involved in autoinhibition of acetylcholine release and vagally-induced vasoconstriction in the rat heart. Stimulation of the vagus nerves (1200 pulses) caused an increase in [14C]-overflow and in perfusion pressure which was significantly reduced by hexamethonium 500 μmol/l and abolished by tetrodotoxin 0.3 μmol/l or perfusion with Ca2+-free solution. The fractional rate of evoked [14C]-overflow per pulse upon stimulation at 10 Hz (720 pulses) was doubled in the presence of the non-selective antagonist atropine (0.01–1 μmol/l) as well as in that of the M2-selective compounds methoctramine (0.1 μmol/l) and AF-DX 116 (0.1–1 μmol/l), but remained unaffected by the M3-selective hexahydrosiladifenidol (0.1 μmol/l). The increase in perfusion pressure upon nerve stimulation was reduced by atropine (0.01 μmol/l) or hexahydrosiladifenidol (0.1 μmol/l) to approximately 50% and increased by about 50% in the presence of AF-DX 116 (0.1 μmol/l). The results show that the autoinhibition of acetylcholine release in the rat heart is mediated by M2 receptors. On the other hand, the increase in perfusion pressure upon vagus nerve stimulation is caused by a different muscarinic receptor, more sensitive to hexahydrosiladifenidol than to M2-selective antagonists.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00180652
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  • 5
    Electronic Resource
    Electronic Resource
    Konfokale Laser-Scanning Mikroskopie (CLSM) (1998)
    Springer
    Mund-, Kiefer- und Gesichtschirurgie 2 (1998), S. 141-145 
    Details
    ISSN: 1434-3940
    Keywords: Schlüsselwörter Konfokale Laser-Scanning-Mikroskopie ; Knochen ; Histotomographie ; Key words Confocal laser scanning microscopy ; Bone ; Histotomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Objectives: Fixation (formalin), decalcification (sections) or mechanical treatment (grinding) all bear the risk of artifacts occurring during hard-tissue histology. Because studies on the etiology of pathological changes mostly focus on subclinical lesions, artifacts can simulate early changes or even be superimposed on existing changes. The objective of this study was to determine how artifacts can be reduced. Material and methods: In confocal laser scanning microscopy (CLSM) a focused laser beam scans the surface of the specimens and penetrates into the tissue. The intensity of the remitted light is recorded. The confocal effect is due to an extremely small aperture (pinhole), excluding light from out-of-focus planes of the sample. By stepwise movement of the object table, a tomographic series of tomographic images is obtained. Sound cortical bone samples of the lower jaw (n = 20) were studied by light microscopy and by CLSM, visualizing identical areas of a ground sectioned sample after H & E staining. Additionally, embedded and fresh blocks of tissue of the same bone sample were studied histotomographically in the CLSM. Results: (1) Light microscopic micromorphology of cortical bone can be visualized adequately in the CLSM; (2) many structures that can be visualized by light microscopy only after special staining (e.g., osteozyte processes) can be visualized by the CLSM using sample blocks without pretreatment. Conclusion: (1) Nondestructive subsurface histotomography by CLSM totally excludes mechanical artifacts; (2) physicochemical artifacts can be handled more easily because fresh samples can be studied; (3) pseudo-three-dimensional imaging allows histological interpretation of the tissue that is equivalent to macroscopic tomographic techniques (CT, MRT).
    Notes: Durch Fixierung (Formalin), Entkalkung (Schnitte) oder mechanische Bearbeitung (Schliffe) besteht bei der Hartgewebshistologie das Risiko physikalisch-chemischer oder mechanischer Artefakte. Da Studien zur Ätiopathogenese pathologischer Veränderungen meist auf subklinische Läsionen zielen, besteht die Gefahr, daß Artefakte frühe Veränderungen vortäuschen oder vorhandene überdecken. Es wird der Frage einer artefaktminimierten Histologie nachgegangen. Bei der konfokalen Laser-Scanning-Mikroskopie (CLSM) rastert ein monochromatischer Laserstrahl über die Probenoberfläche und dringt in das Gewebe ein. Die Intensität der remittierten Strahlung wird in einem Detektor gemessen. Durch eine konfokale Blende (pinhole) erreicht nur Laserlicht aus einer extrem dünnen In-Fokus-Ebene den Detektor, so daß schrittweises Bewegen des Objekttischs eine tomographische Serie von Einzelbildern visualisiert. Gesunde kortikale Knochenproben des Unterkiefers (n = 20) wurden durchlichtmikroskopisch und im CLSM untersucht: Dabei wurden identische Probenareale an Dünnschliffen nach HE-Färbung visualisiert. Außerdem wurden eingebettete und frische Gewebeblöcke derselben Knochenproben im CLSM histotomographiert. Als Ergebnisse wurden gefunden: 1. Lichtmikroskopische Mikromorphologie kortikalen Knochens ist im CLSM valide visualisierbar. 2. Viele lichtmikroskopisch erst nach Spezialfärbungen darstellbare Strukturen (z.B. Osteozytenfortsätze) können im CLSM an Probenblöcken ohne Vorbereitung mikroskopiert werden. Hieraus können folgende Schlußfolgerungen gezogen werden: 1. Die zerstörungsfreie Histotomographie des CLSM unter der Probenoberfläche vermeidet mechanische Artefakte völlig. 2. Physikalisch-chemische Artefakte werden kontrollierbar, da auch frische Proben mikroskopiert werden können. 3. Die pseudo-dreidimensionale Darstellung erlaubt eine histologische Gewebeinterpretation, die makroskopischen Schichtbildverfahren (CT, MRT) vergleichbar ist.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100060050049
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  • 6
    Electronic Resource
    Electronic Resource
    Association between “diabetic thick skin syndrome” and neurological disorders in diabetes mellitus (1994)
    Springer
    Acta diabetologica 31 (1994), S. 73-77 
    Details
    ISSN: 1432-5233
    Keywords: Diabetes mellitus ; Skin thickness ; Diabetic neuropathy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Skin thickness on the extremities of patients with diabetes mellitus has been described controversially. Using high resolution ultrasonography, we were able to show a significant increase in skin thickness at the forearm (P〈0.05), thigh (P〈0.001) and lower limb (P〈0.05) of diabetic patients, most prominent at the thigh. No difference in skin thickness was found at the dorsum of the foot. In addition, skin thickness was not related to the duration of diabetes, age or HbA1. A close association was found between diabetic neuropathy and increasing skin thickness. Diabetic patients with neurological disorders had a significant increase in skin thickness versus diabetic patients without neuropathy. The present findings suggest that diabetic neuropathy and abnormalities of connective tissue have a common etiological link in their development or that both are time-dependent processes. Whether changes in capillary blood flow, increase of nonenzymatic glycosylation, polyol accumulation or other metabolic disorders are responsible for these findings remains still to be established.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00570538
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  • 7
    Electronic Resource
    Electronic Resource
    Architecture in cortical bone and ultrasound transmission velocity (1993)
    Springer
    Clinical rheumatology 12 (1993), S. 364-367 
    Details
    ISSN: 1434-9949
    Keywords: Ultrasound ; Cortical bone ; Mechanical Properties ; Architecture ; Modulus of Elasticity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The square of ultrasound transmission velocity in a material is correlated to the modulus of elasticity, which is an indicator of its mechanical properties. This might make the measurement of ultrasound transmission velocity useful in the noninvasive diagnosis of bone diseases. Bone, however, is not an isotropic material but is architecturally structured. The aim of our study was to investigate and especially to quantify the influence of architecture in cortical bone on ultrasound transmission velocity. Twenty-two rectangular, flat specimens of cortical bone were prepared from diaphysis of fresh pig radius. Ultrasound transmission velocity was measured parallel and perpendicular to direction of Haversian channels. It was found to be 3647 ± 41 m/s parallel to and 2821 ± 29 m/s perpendicular to Haversian channels respectively (p〈0.001). Our results clearly indicate that there is an important influence of architecture in cortical bone on ultrasound transmission velocity which has to be taken into account in its clinical use.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02231581
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  • 8
    Electronic Resource
    Electronic Resource
    In-vivo investigation of material quality of bone tissue by measuring apparent phalangeal ultrasound transmission velocity (1995)
    Springer
    Clinical rheumatology 14 (1995), S. 26-34 
    Details
    ISSN: 1434-9949
    Keywords: Ultrasound ; Bone ; Material Quality ; Modulus of Elasticity ; Age ; Bone Mineral Density
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The square of ultrasound transmission velocity in a material is related to the modulus of elasticity, which is known to be an indicator of stability in bone. The aim of our study was to use ultrasound transmission velocity to obtain information about the material properties of bone tissue, keeping other factors possibly influencing ultrasound transmission as constant as possible. Apparent phalangeal ultrasound transmission velocity (APU) measured in 54 isolated, fresh pig phalanges was shown to be independent of bone mineral density (BMD) measured by SPA. Fastest sound transmission led exclusively through cortical bone so that intertrabecular connectivity in spongious bone could not influence the result. In humans APU was measured in the mediolateral direction at the midphalanx of the middle finger. In 53 healthy subjects (15–81 years old; 27 women, 26 men), there was a decrease of APU with age (r=−0.30, p〈0.05). Further, when comparing the results of both hands intraindividually almost identical values indicated constant intraindividual architecture of bone at this location. There was no evidence for a relation of APU to physical load comparing dominant and nondominant hand and relating the results to subjectively estimated physical load. In a second group of 43 perimenopausal women (47–60 years old), APU, which again decreased with age (r=−0.33, p〈0.05), was found not be correlated to BMD measured by SPA at the distal forearm (cortical bone). In a third group of 40 women (17–78 years old), APU again decreased with age (r=−0.60, p〈0.001) and was not correlated to BMD measured by SPA at the midphalanx of the middle finger, i.e. the same measuring location as APU. We conclude that this method provides information about the modulus of elasticity of bone with negligible influence of bone mineral density. Our results indicate that there is a deterioration of bone material quality with age independent of decreasing bone mineral density.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02208081
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