Non-specific symbiotic germination of Cynorkis purpurea (Thouars) Kraezl., a habitat-specific terrestrial orchid from the Central Highlands of Madagascar.

Orchids, particularly terrestrial taxa, rely mostly on basidiomycete fungi in the Cantharellales and Sebacinales that trigger the process of seed germination and/or initiate the full development of the seedling. During the course of development, orchids may associate with the same fungus, or they may enlist other types of fungi for their developmental needs leading to resilience in a natural setting. This study examined in vitro seed germination and seedling developmental behavior of Cynorkis purpurea, a terrestrial orchid from the Central Highlands of Madagascar. This species is mostly restricted to gallery forests in the Itremo Massif, in moist substrate between rocks bordering streams. The main objective was to understand the influence of diverse mycorrhizal fungi on seed germination and further development of C. purpurea. The study aims to compare symbiotic versus asymbiotic germination and seedling development with seeds and fungi collected from a 13-km(2) area in the Itremo region. Seeds collected from the wild were sown with diverse orchid mycorrhizal fungi (OMF) spanning 12 operational taxonomic units (OTUs) in three genera (Tulasnella, Ceratobasidium, and Sebacina) acquired from different habitats. Treatments were assessed in terms of the percentage of germinated seeds and fully developed seedlings against those in asymbiotic control media treatments. Overall, OMF significantly improved seedling development within the 12-week experiment period. Sebacina as a genus was the most effective at promoting seedling development of C. purpurea, as well as having the ability to enter into successful symbiotic relationships with orchids of different life forms; this new knowledge may be especially useful for orchid conservation practiced in tropical areas like Madagascar. A Sebacina isolate from an epiphytic seedling of Polystachya concreta was the most effective at inducing rapid seedling development and was among the five that outperformed fungi isolated from roots of C. purpurea. C. purpurea was found to be a mycorrhizal generalist, despite its specific habitat preference, highlighting the complex interaction between the plant, fungi, and the environment. The potential impact on conservation strategies of understanding the requirements for orchid seed germination and development by identifying and using OMF from diverse sources is discussed in detail.

Evaluation of healing with use of an internal matrix to repair furcation perforations.

AIM: The purpose of this study was to evaluate healing responses following repair of furcation perforations, with and without an internal matrix. Two matrix materials, HAPSET (65% non-resorbable hydroxyapatite and 35% plaster of paris) and hydroxyapatite were compared. METHODOLOGY: Four adult female baboons (Papio anubis) served as experimental models. Furcation perforations were made in the molar and premolar teeth, which were then randomly assigned to one of the five groups, according to the method of perforation repair: 1 Experimental group 1 (16 teeth): The matrix material was HAPSET and the sealing material, amalgam. 2 Experimental group 2 (16 teeth): The matrix material was hydroxyapatite and the sealing material, amalgam. 3 Experimental group 3 (16 teeth): No matrix was placed. The sealing material was amalgam. 4 Positive control group (16 teeth): The perforation was not sealed. 5 Negative control group (16 teeth): No perforation was made. The animals were sacrificed at 1 week and 1, 3 and 7 months. Specimens were prepared for examination with light microscopy. RESULTS: The data revealed that when amalgam was used alone without a matrix, there was marked extrusion of the material into the underlying bone with an associated severe inflammatory response, which continued throughout the observational period. When an internal matrix was used, there was an initial acute inflammatory response that diminished with time such that at 7 months, 75% of these specimens were free of inflammation. There was no difference in the tissue response to the different matrix materials. HAPSET and hydroxyapatite underwent connective tissue encapsulation in the early stages followed by new bone deposition in direct contact with the materials. CONCLUSIONS: Within this animal model healing responses are better when an internal matrix, whether HAPSET or hydroxyapatite, is used in the repair of furcation perforations.

Emerging methods used in the prevention and repair of carious tissues.

A systematic review was undertaken to investigate four emerging methodologies that might be used in the prevention of caries and/or repair of carious tissues. These included a partitioned dentifrice, laser technology, fluoride-releasing dental materials, and for deep carious lesions, bone morphogenic protein (BMP) therapy. The search strategy was to review articles written in English, indexed in MEDLINE and EMBASE databases and published since 1976. Over two hundred articles were read but because of the inclusion and exclusion criteria, only thirty-three were included in the evidence tables. The review of partitioned toothpaste showed either a greater remineralizing effect or a greater increase in the resistance to demineralization of both enamel and dentin, with the exception of its lack of effectiveness on coronal caries in the only clinical trial. Five of the six in vitro studies on enamel and the one study on dentin reported that lased tissue was less soluble than nonlased. Six clinical and four in situ studies were reviewed in answering the question as to whether fluoride-releasing restorative materials increase the remineralization or resistance to demineralization of human enamel and dentin. Eight of these reported positive findings. Six animal studies investigating BMP were reviewed, and all showed the ability of BMP to induce tubular dentin formation. Although the laboratory, animal, and limited clinical trials report encouraging results, independent, randomized, controlled clinical trials need to be carried out before these emerging technologies can be recommended for use in general practice.

Enoxacin in the therapy of anal and pharyngeal gonococcal infections.

In this randomized double-blind study, 51 patients with uncomplicated anal or pharyngeal Neisseria gonorrhoeae infection were evaluated to determine the efficacy and safety of 200- or 400-mg of enoxacin twice a day for two days. Enoxacin cured all anal infections and 12 out of 13 pharyngeal infections. All 82 isolates of N. gonorrhoeae tested were inhibited by 1 microgram of enoxacin/ml.