Isolation of precursor cells (PCs) from human dental follicle of wisdom teeth.

The dental follicle is an ectomesenchymal tissue surrounding the developing tooth germ. It is believed that this tissue contains stem cells and lineage committed progenitor cells or precursor cells (PCs) for cementoblasts, periodontal ligament cells, and osteoblasts. In this study, we report the isolation of PCs derived from dental follicle of human third molar teeth. These fibroblast-like, colony forming and plastic adherent cells expressed putative stem cell markers Notch-1 and Nestin. We compared gene expressions of PCs, human mesenchymal stem cells (hMSCs), periodontal ligament cells (PDL-cells) and osteoblasts (MG63) for delimitation of PCs. Interestingly, PCs expressed higher amounts of insulin-like growth factor-2 (IGF-2) transcripts than hMSCs. Differentiation capacity was demonstrated under in vitro conditions for PCs. Long-term cultures with dexamethasone produced compact calcified nodules or appeared as plain membrane structures of different dimensions consisting of a connective tissue like matrix encapsulated by a mesothelium-like cellular structure. PCs differentially express osteocalcin (OCN) and bone sialoprotein (BS) after transplantation in immunocompromised mice but without any sign of cementum or bone formation. Therefore, our results demonstrate that cultured PCs are unique undifferentiated lineage committed cells residing in the periodontium prior or during tooth eruption.

A candidate olfactory receptor subtype highly conserved across different insect orders.

Candidate olfactory receptors of the moth Heliothis virescens were found to be extremely diverse from receptors of the fruitfly Drosophila melanogaster and the mosquito Anopheles gambiae, but there is one exception. The moth receptor type HR2 shares a rather high degree of sequence identity with one olfactory receptor type both from Drosophila (Dor83b) and from Anopheles (AgamGPRor7); moreover, in contrast to all other receptors, this unique receptor type is expressed in numerous antennal neurons. Here we describe the identification of HR2 homologues in two further lepidopteran species, the moths Antheraea pernyi and Bombyx mori, which share 86-88% of their amino acids. In addition, based on RT-PCR experiments HR2 homologues were discovered in antennal cDNA of the honey bee (Apis mellifera; Hymenoptera), the blowfly (Calliphora erythrocephala; Diptera) and the mealworm (Tenebrio molitor; Coleoptera). Comparison of all HR2-related receptors revealed a high degree of sequence conservation across insect orders. In situ hybridization of antennal sections from the bee and the blowfly support the notion that HR2-related receptors are generally expressed in a very large number of antennal cells. This, together with the high degree of conservation suggests that this unique receptor subtype may fulfill a special function in chemosensory neurons of insects.

Statistical evaluation of ecosystem properties influencing the uptake of As, Cd, Co, Cu, Hg, Mn, Ni, Pb and Zn in seaweed (Eucus vesiculosus) and common mussel (Mytilus edulis).

In order to evaluate the influence of geographically varying marine ecosystem properties on the uptake of trace elements in bioindicators, samples were taken of seaweed (Fucus vesiculosus) and common mussel (Mytilus edulis) along the North Sea and Baltic Sea coast. Seasonal variations of the bioindicator status were minimized by sampling within 1 month. Ecosystem properties considered were the geographical position, the salinity and the concentrations of the macroelements Ca, Fe, K, Mg, Na, P and S in the bioindicators. Trace elements studied were As, Cd, Co, Cu, Hg, Mn, Ni, Pb and Zn. Factor analysis of the concentration patterns in the bioindicators and of salinity as a function of location confirmed the influence of the geographically varying salinity on the biological uptake of macroelements and trace elements. This influence of salinity was higher in the case of seaweed than in the case of mussel. Comparison of the geographical courses of the macroelement and trace-element concentrations by cluster analysis revealed corresponding courses for As and Hg in both bioindicators. All other elements showed different courses in seaweed and mussel. Subsequent cluster analysis comparing locations with respect to the macroelement or trace-element concentration patterns in the bioindicators, indicated a clear separation of North and Baltic Sea locations. However, the trace-element concentration patterns provided a regionally less distinctive ecosystem arrangement than those of the macroelement ones. The results of the cluster analysis were verified by discriminant analysis forming groups of locations with respect to geographical position and salinity. Results of discriminant analysis demonstrated, both for seaweed and for mussel as bioindicators, that the location groups formed according to the macroelement concentration patterns corresponded well with the geographical regions in the order of salinity. On the other hand, location groups based on the trace-element concentration patterns again showed a modified less distinctive ecosystem arrangement than the location groups based on macroelement concentration patterns. This confirms modified conditions for the uptake of trace elements in seaweed or mussel in comparison to the uptake of macroelements.

Mussels and algae as bioindicators for long-term tendencies of element pollution in marine ecosystems.

Results of more than ten years of experience in the determination of metals in mussels and algae collected in the North Sea and the Baltic Sea are presented. The various elements determined here are Hg, As, Se, Cd, Pb, Cu, Na, K, S, P, Zn, Mn, Fe, Sr, Ca, Ba, Mg, Tl, Ni, Co using techniques such as cold vapor AAS, INAA, hydride generation AAS, electrothermal AAS, ICP-AES, IDMS and stripping voltammetry. The results indicate the occurrence of three groups of elements with respect to long-term tendencies of their concentrations. In the first group, the concentrations in both mussels and algae varied in the same manner; in the second group no change was observed in either matrix while in the third group, the concentrations of elements changed in an opposite manner.

Reference materials and environmental specimen banking.

The preservation and protection of the environment has become a major challenge of our times since this has to be compatible with the ecological needs. The concept of Environmental Specimen Banking (ESB) acquires importance in providing the data base for deeper insight into ecochemical processes. Methodological development and preparation of reference materials (RMs) are also essential to such studies. Systematic efforts are to be made to acquire a good number of reference materials to be useful for analysis of toxic as well as essential components. Our experience has shown that it is possible to procure worthy and scientifically valuable specimens from soils and leafy food substances. Exploring preparation of suitable specimens from a country such as India might be a worthy exercise since it is possible to obtain clean specimens in this part of the world. Analytical data for determination of some trace and major elements in prepared RMs are presented.

Mobilizable lead in patients with chronic renal failure.

Blood lead (Pb) and urinary Pb before and after i.v. infusion of 1 g of Na2Ca EDTA were determined (atomic absorption) in 46 control subjects and 91 patients with various stages of renal failure (median serum creatinine 2.5 mg dl-1). Under baseline conditions, patients with renal failure had higher blood Pb levels (112 ng ml-1, range 44-272 vs. 76; 36-187 in controls; P less than 0.001) and lower urinary Pb (16.2 nmol 24 h-1 1.73 m-2, 4.86-66.8 vs. 33; 11-91 in controls; P = 0.001). The increment in urinary Pb after EDTA infusion (mobilizable Pb) was higher (795 nmol 4 days-1 1.73 m-2, range 155-5611 vs. 307; 131-1587 in controls; P = 0.001). In 12 patients with renal failure (13%) mobilizable Pb was above the highest value in controls. Mobilizable urinary Pb correlated (r = 0.68) significantly (P = 0.001) with blood Pb, but only marginally with serum creatinine (r = 0.32; P less than 0.007). Mobilizable Pb was higher in patients with renal failure and a history of smoking or occupational Pb exposure and tended to be higher in patients with alcoholism. Ten of 91 patients had gout; increased mobilizable Pb was present in three of the 10. The data confirm relatively high prevalence of elevated body Pb burden in European patients with chronic renal failure. The question is unresolved whether Pb plays a role in the progression of renal failure.

Urinary lead excretion in uremic patients.

Urinary excretion of lead (Pb) was measured in the basal state and following the infusion of EDTA (1g of calcium disodium edetate) in healthy German controls and in patients with chronic renal failure with and without gout. When evaluated with Zeeman-compensated atomic absorption spectroscopy using the L'vov platform and urine pretreated with nitric acid and Triton X-100, the control basal Pb excretion (median 28, range 11-19 nmol Pb/24h) and the postinfusion Pb increment (306, range 131-1,587 nmol/4 days/1.73 m2) were considerably lower than most values reported previously in the literature. Elevated Pb body burden was found in 7 of 8 patients who developed gout in the course of renal failure, but only in 2 of 8 patients who had gout prior to development of renal failure; this confirms that appearance of gout in patients with renal failure points to prior Pb exposure. In 7 of 19 nongouty patients with impaired renal function secondary to known renal diseases, urinary Pb excretion was above the 95th percentile of normal. All these patients had occupational Pb exposure. The high prevalence of elevated Pb body burden in patients with renal failure of known cause may not be coincidental and raises the possibility that Pb adversely affects the course of renal disease.

Metal analysis in difficult materials with platform furnace Zeeman-atomic absorption spectroscopy. 2. Direct determination of cadmium and lead in milk.

A procedure is described for the direct determination of cadmium and lead in whole milk, skim milk, condensed milk, and human milk. Using a Perkin-Elmer 5000 Z instrument with HGA 500 and L'vov platform and by application of oxygen ashing at approx. 600 degrees C, determination limits of approx. 0.02 microgram/l and 0.7 microgram/l for cadmium and lead, respectively, are attainable. Day-to-day precision is 10% for 0.1 microgram/l of cadmium and 2 micrograms/l of lead. Accuracy control at least at higher levels was possible with DPASV after wet digestion. The contents found with this procedure in cows milk are at the lowest limit of very recent literature data, i.e. on average at 0.05 microgram/l for cadmium and 2 microgram/l for lead for samples from nonpolluted regions. The results indicate that milk does not contribute significantly to heavy metal exposure of man.