One of the key factors for attaining osseointegration is the presence of an adequate osseous volume. In patients with inadequate osseous width or height, a bone augmentation using the guided bone regeneration (GBR) concept may be applied either with a simultaneous or a staged approach. The aim of this multicenter prospective case series study was to evaluate the efficacy and predictability of the GBR technique (simultaneous approach) in patients with peri-implant osseous defects, both dehiscences and fenestrations. Results 5 years post-treatment (survival rates and marginal bone level) were assessed. A total of 19 consecutive patients with 26 peri-implant osseous defects (20 dehiscences and six fenestrations) were treated during the period from September 1992 to June 1993 with a simultaneous GBR approach using non-resorbable membranes combined with autogenous bone grafts or decalcified freeze-dried bone allograft. The mean osseous augmentation was 94.8%. Marginal bone levels at re-entry and 5 years after surgery were calculated from standardized periapical radiographs. One implant was lost 3 months after loading. Thus, the cumulative survival rate was 96.1% after 5 years. The mean marginal bone level after 5 years was 2.03 mm (SD=+/-0.5), without a difference between mesial and distal sites. This study demonstrates that implants with peri-implant defects that are treated with GBR had similar survival rates and crestal bone levels compared with implants in native bone.

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High production of viable somatic embryos was obtained from cultured anthers in the second phase of meiosis, using microscopic level observations of tetrads. The medium with the greatest embryogenic efficiency was H6, composed of Murashige and Skoog (MS) medium with 2 mg l À1 of 2,4-dichlorophenoxyacetic acid (2,4-D) and 0.5 mg l À1 of kinetin. All (100%) of the somatic embryos obtained germinated and produced 63% green and 37% albino seedlings. In general, embryogenic calli had a higher ion concentration than non-embryogenic calli, with the exception of calcium whose concentration was higher in non-embryogenic calli. The calli induced in the different media differed in their sucrose and starch compositions. The most embryogenic medium H6-induced calli with the highest sucrose concentration and the lowest starch concentration, before visible embryos were observed. In the leaves of the albino seedlings, sucrose concentrations were very high while those of starch were very low. Ion concentrations were also lower in albino plants than in the leaves of green seedlings, with the exception of calcium, whose concentration was higher. Most of the albino individuals were homozygous, even when their progenitors were heterozygous, thereby confirming their haploid nature.

Two square planar derivatives of Pt(en)Cl(2) with intrinsic fluorescence in aqueous solution at room temperature, with quantum yields (Phi) 0.11 and 0.10, respectively, have been synthesized and characterized as [Pt(en)(CG)Cl] (Complex 1) and [Pt(en)(CG)(2)] (Complex 2) (en = ethylenediamine, CG = cholylglycinate). Complexes 1 and 2 exchange just one ligand (chloride or cholylglycinate, respectively) when reacted with water or 5'-GMP to give the same chemical species. After reaction with DNA oligonucleotides or DNA plasmids, they show enhanced emission in the visible region, which lasts for long periods of time and makes them potentially useful DNA marker molecules. Incubation with nucleated blood cells followed by microscopic analyses revealed that they enter the cells within minutes of exposure, selectively stain the DNA, and persist after more than 48 h of exposure. Complexes 1 and 2 display cell cycle phase-independent cytotoxic activity against cisplatin-resistant CHO (Chinese hamster ovarian) tumor cells, with an early onset of their effects. Their slightly different biological effects, as compared to cisplatin, are considered to be linked to the bile acids and their vector properties and to the preferential formation of monoadducts.