Das piezoelektrische Verhalten der menschlichen Zahnhartgewebe

Zusammenfassung Bei menschlichen Zähnen wurde piezoelektrisches Verhalten festgestellt; dieses ist gebunden an den Kollagenfaseranteil des Dentins und des Zahnzementes. Schmelz ist nicht piezoelektrisch; entmineralisierte Zähne zeigen ein verstärktes piezoelektrisches Verhalten.Es besteht eine piezoelektrische Achse in der physiologischen Zahnlängsrichtung, deren Richtungssinn bei allen Zähnen des Ober- und Unterkiefers gleich ist und offenbar der morphogenetischen Entwicklungsrichtung des Zahnes entspricht. Außerdem besteht rund um die piezoelektrische Längsachse herum in allen radialen Richtungen zwischen Pulpahöhle und Zahnaußenseite piezoelektrisches Verhalten, das möglicherweise in Beziehung zur Struktur der Dentinlamellen und damit zur morphogenetischen Zahnentwicklung in radialer Richtung steht.Die piezoelektrischen Effekte zeigen von Zahn zu Zahn eine erhebliche biologische Streubreite. Bei unserem Untersuchungsmaterial lagen die Effekte zwischen 3,5·10^–10 und 1,9·10^–9 est E Ldg./dyn. Diese Werte entsprechen etwa 0,5 bis 2,8% des piezoelektrischen Koeffizienten d₁₁ von -Quarz.

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Summary Human teeth are piezoelectric. This is due to the collagen-fibril content of the dentine and tooth cement. Enamel is not piezoelectric; decalcified teeth show increased piezoelectric behaviour.There is a piezoelectrical axis corresponding to the physiological longitudinal tooth axis, which is in the same direction in all teeth of both upper and lower jaws, and which seems to correspond to the morphogenetical development axis of teeth. Piezoelectric behaviour also exists between the pulp cavity and outer surface of the tooth in all directions radial to the piezoelectric longitudinal axis. The latter is possibly due to the dentine lamellae, and therefore may be connected with the radial direction of morphogenetical tooth development.The piezoelectric effects show large biological variations in different teeth. The effects from our research materials vary between 3.5·10^–10 and 1.9·10^–9 e.s.u./dynes. These results correspond to about 0.5 to 2.8% of the piezoelectrical coefficient d₁₁ of -quartz.

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Unterstützt durch Sachbeihilfen der Deutschen Forschungsgemeinschaft.

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cand. med. dent. und derzeit Doktorand an der Klinik und Poliklinik für Zahn-, Mund- und Kieferkrankheiten, Universität Kiel.     

Bellevalia ciliata (Cyr.) Nees (Hyacinthaceae) neu für Bulgarien

(Bellevalia ciliata was recorded in north-east Bulgaria south of the Dobrudsha, within field and steppe vegetation. Vegetation records and a distribution map are presented. Based on taxonomic studies it is proposed to combineB. ciliata, B. sarmatica (Pall.) Wor. andB. speciosa Wor. under the oldest nameB. ciliata (Cyr.) Nees.     

Poly- and Monoclonal Antibodies Against Recombinant Rat Brain Calbindin D-28K Were Produced to Map Its Selective Distribution in the Central Nervous System

Many processes in the CNS depend on calcium. The calcium signal is transduced into an intracellular response via Ca2(+)-binding proteins, including calbindin D-28K. In many laboratories, polyclonal antibodies against chicken intestinal calbindin D-28K have been used to study its localization in the brain (normal and degenerated) of various species, including humans, but some of these antisera cross-reacted with other proteins, including calretinin. We purified recombinant rat brain calbindin D-28K to raise antisera in rabbits and purified a recombinant rat-chicken calbindin D-28K hybrid protein to immunize mice for the generation of monoclonal antibodies. These antisera were highly specific for calbindin D-28K, as demonstrated by two-dimensional Western blotting analysis. Immunohistochemical analyses combined with in situ hybridization studies demonstrated that calbindin D-28K in the Purkinje cells of the cerebellum is independent of vitamin D. The antibodies described here will be important tools for studying the regulation of expression of calbindin D-28K and its biological function in the brain and in the PNS.     

A microdeletion of less than 250 kb, including the proximal part of the FMR-1 gene and the fragile-X site, in a male with the clinical phenotype of fragile-X syndrome

A gene designated "FMR-1" has been isolated at the fragile-X locus. One exon of this gene is carried on a 5.1-kb EcoRI fragment that exhibits length variation in fragile-X patients because of amplification of or insertion into a CGG-repeat sequence. This repeat probably represents the fragile site. The EcoRI fragment also includes an HTF island that is hypermethylated in fragile-X patients showing absence of FMR-1 mRNA. In this paper, we present further evidence that the FMR-1 gene is involved in the clinical manifestation of the fragile-X syndrome and also in the expression of the cellular phenotype. A deletion including the HTF island and exons of the FMR-1 gene was detected in a fragile X-negative mentally retarded male who presented the clinical phenotype of the fragile-X syndrome. The deletion involves less than 250 kb of genomic DNA, including DXS548 and at least five exons of the FMR-1 gene. These data support the hypothesis that loss of function of the FMR-1 gene leads to the clinical phenotype of the fragile-X syndrome. In the fragile-X syndrome, there are pathogenetic mechanisms other than amplification of the CGG repeat that do have the same phenotypic consequences.     

Prey selection of the shallow water fishPomatoschistus minutus (Gobiidae,Teleostei) in the SW Baltic

The aim of this investigation is to demonstrate the reasons of an opportunist feeder to select some components of the available food supply and to avoid others. Object of this test is the eurytopic and euryhaline sand goby,Pomatoschistus minutus (Pallas), from the Luebeck Bight. It inhabits both sand habitats as well as bottoms mixed with pebbles or continuous hard substrates. Therefore, it is often in close contact withMytilus-belts which present a very rich food supply of small crustaceans. The selectivity behaviour of sand gobies from a sand/clay ecotone was compared with that of populations from a stony pier and a sand bottom during the reproduction period. Regarding the numbers of prey organisms, crustaceans of the periphyton were generally preferred at the pier but avoided in the ecotone. The same is valid for prey organisms of the psammal which were preferred by gobies of the sand bottom but mostly avoided by populations of mixed bottoms. Analyses of size selections revealed that the preferred gammarids orJaera isopods were between 2 and 5 mm length. A balanced relation of goby biomass and utilizable food supply (predatory impact index) seems to effect positive selectivity of gammarids in theMytilus-belts or of harpacticoids in the sand bottom.     

Epidemiology of Malignant Melanoma in Central Europe: Risk Factors and Prognostic Predictors. Results of the Central Malignant Melanoma Registry of the German Dermatological Society

The Central Malignant Melanoma Registry (CMMR) of the German Dermatological Society was established in 1983, and 7789 cutaneous malignant melanomas (CMM) were registered by 35 dermatological departments in Germany, Austria and Switzerland until the end of 1989. Population-based incidence rates, risk factors for developing CMM and prognostic parameters for predicting the final outcome were investigated in separate multicenter studies performed by the CMMR. Among the 7789 CMM registered, there was a preponderance of females (57.7%) versus males (42.3%). The age distribution peaked in the 5th and 6th decade of life for both sexes with a mean age of 52 years. The mean detection age was 50 years for superficial spreading melanoma, 53 for nodular melanoma, and 65 for lentigo maligna melanoma. Mean tumor thickness decreased from 2 mm in 1983 to 1.5 mm in 1989, indicating better CMM-awareness of the population and the medical community in this area. 90% of the patients presented with clinical stage I CMM without detectable metastases at first diagnosis. The incidence of CMM in Berlin (West) was assessed based on 960 cases diagnosed between 1980 and 1986. The incidence increased by 49% between 1980-81 and 1985-86, and the age standardized-incidence rate (European standard population) was 9.8 for males and 7.8 for females per 100,000 inhabitants and year in 1985-86. Mortality rates decreased in this period from 3.5 to 2.6 for males and slightly increased for females from 1.2 to 1.6 per 100,000 inhabitants and year. A case control study on the relative risk (RR) for developing CMM revealed the total number of melanocytic nevi (MCN) to be the strongest risk predictor (15x - 50x increased RR), followed by the presence of dysplastic MCN (7x increased RR) and the skin type I (2x increased RR). Interestingly, no differences between CMM-cases and controls were found with respect to the history of sunburns or other parameters of sun exposure in this study. Multivariate analysis of 5093 stage I CMM-patients from four departments with long-term follow-up revealed that tumor thickness is the strongest predictor of survival with an almost linear correlation to the risk of death for tumor thickness up to 6 mm with no further increase in mortality for higher tumor thickness. The best classification of tumor thickness for survival prediction was 1 mm, 1.01 ?2 mm, 2.01 ?4 mm and > 4 mm in our data set on 5093 patients. Sex was found to be the second most important prognostic factor showing a significant advantage for females. Furthermore, a high risk was identified for tumors localized on the upper trunk, upper arm, neck and scalp on the upper trunk, upper arm, neck and scalp (=TANS); the anatomical site, therefore, should be taken into account for a prognostic classification of primary CMM.     

Approximate digestibility of fibre for a graminivorous caterpillar

Final instar Persectania ewingii (Westwood) (Lepidoptera: Noctuidae) were fed seedling Triticum aestivum L. for 2 days to determine the approximate digestibility of the cell wall and cell content fractions. Cell wall content was estimated using a micro-analytical neutral detergent fibre technique. Approximate digestibilites of neutral detergent fibre, neutral detergent solubles and dry matter were calculated for individuals and pooled samples. P. ewingii larvae digested a small but significant proportion of the fibre ingested (13–21%), higher than that previously reported for herbivorous insects. The micro-analytical and previously used macro-analytical techniques produced similar estimates of digestibility although both techniques have inherent shortcomings, the latter requiring the pooling of samplex and the former limiting the number of replicates during chemical analysis. Differences in the amount of larval frass collected during the feeding trial (corrected for consumption) explained much of the variation in digestibility values, while there were no effects of larval mass, overall consumption and total frass produced on digestibility estimates. These results confirm that plant cell contents are the major source of nutrients to larval Lepidoptera although there is some chemical disruption of the plant cell wall.