RESUMO
Intraspecific and habitat-mediated responses to chemical cues play key roles in structuring populations of marine species. We investigated the behaviour of herbivorous-stage juvenile crown-of-thorns sea stars (COTS; Acanthaster sp.) in flow-through choice chambers to determine if chemical cues from their habitat influence movement and their transition to become coral predators. Juveniles at the diet transition stage were exposed to cues from their nursery habitat (coral rubble-crustose coralline algae (CCA)), live coral and adult COTS to determine if waterborne cues influence movement. In response to CCA and coral as sole cues, juveniles moved towards the cue source and when these cues were presented in combination, they exhibited a preference for coral. Juveniles moved away from adult COTS cues. Exposure to food cues (coral, CCA) in the presence of adult cues resulted in variable responses. Our results suggest a feedback mechanism whereby juvenile behaviour is mediated by adult chemical cues. Cues from the adult population may deter juveniles from the switch to corallivory. As outbreaks wane, juveniles released from competition may serve as a proximate source of outbreaks, supporting the juveniles-in-waiting hypothesis. The accumulation of juveniles within the reef infrastructure is an underappreciated potential source of COTS outbreaks that devastate coral reefs.
Assuntos
Antozoários , Sinais (Psicologia) , Estrelas-do-Mar , Animais , Antozoários/fisiologia , Estrelas-do-Mar/fisiologia , Recifes de Corais , Herbivoria , Ecossistema , Comportamento Alimentar , Rodófitas/fisiologiaRESUMO
Difunctionalization of strained cyclic alkynes presents a powerful strategy to build richly functionalized cyclic alkenes in an expedient fashion. Herein we disclose an efficient and flexible approach to achieve carbohalogenation, dicarbofunctionalization, aminohalogenation and aminocarbonation of readily available cyclohexenyl triflates. We have demonstrated the novel use of zincate base/nucleophile system for effective formation of key cyclohexyne intermediates and selective addition of various carbon and nitrogen nucleophiles. Importantly, leveraging the resulting organozincates enables the incorporation of a broad range of electrophilic partners to deliver structurally diverse cyclohexene motifs. The importance and utility of this method is also exemplified by the modularity of this approach and the ease in which even highly complex polycyclic scaffolds can be accessed in one step.
RESUMO
OBJECTIVES: To compare the effects of particle abrasion medium and pressure on shear bond strength and biaxial flexural strength of three generations of zirconia (Lava Frame, Lava Plus, and Lava Esthetic) with the goal of optimizing the bond to zirconia. METHODS: 280 discs (14 mm diameter; 1 mm thickness) of each zirconia were milled and sintered. Specimens of each material were randomly distributed into 14 groups (n=20); half were tested for shear bond strength and half were tested for biaxial flexural strength. The specimens were particle abraded on one surface by 2 different media (50 µm alumina particles or 50 µm glass beads) for 10 seconds at three different pressures (15, 30, and 45 psi or 0.1, 0.2, 0.3 MPa). Untreated specimens served as positive control. A tube (1.50 mm diameter) filled with dual cured resin cement (Panavia SA) was placed onto the surface and light cured. Specimens were stored in water (37°C for 24 hours) and shear bond strength was measured in a universal testing machine (Instron). Biaxial flexural strength of each specimen was measured according to ISO 6872. Shear bond strength and biaxial flexural strength were compared individually with a 2-way analysis of variance (ANOVA) for factors surface treatment and zirconia composition. RESULTS: Significant differences were seen between surface treatments (p<0.01), zirconia composition (p<0.01) and their interaction (p<0.01) for both bond strength and flexural strength. With alumina particle abrasion, higher pressure produced higher bonds for Lava Frame and Lava Plus zirconia while the bond of Lava Esthetic declined with increased pressure. Higher pressure (>0.2 MPa or 30 psi) with alumina decreased biaxial flexural strength with Lava Esthetic zirconia. CONCLUSIONS: Particle abrasion with alumina produced a significantly better combination of bond strength while maintaining biaxial strength of three zirconia materials than particle abrasion with glass beads. The bond strength also depended upon the pressure of particle abrasion and the generation of zirconia used.
Assuntos
Colagem Dentária , Resistência à Flexão , Propriedades de Superfície , Teste de Materiais , Zircônio/química , Cimentos de Resina/química , Resistência ao Cisalhamento , Óxido de Alumínio , Análise do Estresse DentárioRESUMO
Eighty-four pairs of acute and convalescent serum samples collected in 1998 and 1999 from 17 outbreaks of respiratory disease, milk drop syndrome or diarrhoea in cattle were tested by haemagglutination inhibition against human influenza viruses A/Eng/333/80 (HIN1) and A/Eng/427/88 (H3N2). Antibodies to these viruses were present in the convalescent sera of 56.5 per cent and 58.8 per cent cattle tested, respectively, with 56 per cent of the animals seroconverting to one or both viruses. Titres were typically higher to A/Eng/427/88 (H3N2). Further testing of a subset of 21 of these serum pairs against the predominant H1N1 and H3N2 human and porcine strains circulating when the samples were collected revealed that the highest reactivity, in terms of both the magnitude of the recorded titres and the number of positive sera, was to human H3N2 strains. The titres to human H1N1 strains and to both porcine subtypes were low or absent. Attempts to isolate influenza A virus from nasal mucus or swab samples from 142 cattle from 46 cases of respiratory disease and/or milk drop syndrome by passage in embryonated specific pathogen-free eggs were unsuccessful.
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Anticorpos Antivirais/sangue , Doenças dos Bovinos/virologia , Vírus da Influenza A/isolamento & purificação , Influenza Humana/veterinária , Mucosa Nasal/virologia , Animais , Bovinos , Doenças dos Bovinos/epidemiologia , Feminino , Testes de Inibição da Hemaglutinação/veterinária , Humanos , Vírus da Influenza A/imunologia , Influenza Humana/epidemiologia , Influenza Humana/virologia , Masculino , Irlanda do Norte/epidemiologia , Estudos RetrospectivosRESUMO
OBJECTIVES: To determine whether thyroxine treatment is effective in patients with symptoms of hypothyroidism but with thyroid function tests within the reference range, and to investigate the effect of thyroxine treatment on psychological and physical wellbeing in healthy participants. DESIGN: Randomised double blind placebo controlled crossover trial. SETTING: Outpatient clinic in a general hospital. PARTICIPANTS: 25 patients with symptoms of hypothyroidism who had thyroid function tests within the reference range, and 19 controls. METHODS: PARTICIPANTS were given thyroxine 100 microgram or placebo to take once a day for 12 weeks. Washout period was six weeks. They were then given the other to take once a day for 12 weeks. All participants were assessed physiologically and psychologically at baseline and on completion of each phase. MAIN OUTCOME MEASURES: Thyroid function tests, measures of cognitive function and of psychological and physical wellbeing. RESULTS: 22 patients and 19 healthy controls completed the study. At baseline, patients' scores on 9 out of 15 psychological measures were impaired when compared with controls. Patients showed a significantly greater response to placebo than controls in 3 out of 15 psychological measures. Healthy participants had significantly lower scores for vitality when taking thyroxine compared to placebo (mean (SD) 60 (17) v 73 (16), P<0.01). However, patients' scores from psychological tests when taking thyroxine were no different from those when taking placebo except for a poorer performance on one visual reproduction test when taking thyroxine. Serum concentrations of free thyroxine increased and those of thyroid stimulating hormone decreased in patients and controls while they were taking thyroxine, confirming compliance with treatment. Although serum concentrations of free triiodothyronine increased in patients and controls taking thyroxine, the difference between the response to placebo and to thyroxine was significant only in the controls. CONCLUSIONS: Thyroxine was no more effective than placebo in improving cognitive function and psychological wellbeing in patients with symptoms of hypothyroidism but thyroid function tests within the reference range. Thyroxine did not improve cognitive function and psychological wellbeing in healthy participants.
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Hipotireoidismo/tratamento farmacológico , Tiroxina/uso terapêutico , Anticorpos/sangue , Colesterol/sangue , Estudos Cross-Over , Método Duplo-Cego , Ferritinas/sangue , Humanos , Hipotireoidismo/fisiopatologia , Hipotireoidismo/psicologia , Iodeto Peroxidase/imunologia , Prolactina/sangue , Testes Psicológicos , Testes de Função Tireóidea , Glândula Tireoide/fisiopatologia , Tireotropina/sangue , Hormônio Liberador de Tireotropina , Tiroxina/sangue , Falha de TratamentoRESUMO
In the search for the ultimate esthetic restorative material, many new all-ceramic systems have been introduced to the market. One such system, In-Ceram, is primarily crystalline in nature, whereas all other forms of ceramics used in dentistry consist primarily of a glass matrix with a crystalline phase as a filler. In-Cream can be used to make all-ceramic crowns and fixed partial denture frameworks. Three forms of In-Ceram, based on alumina, spinal (a mixture of alumina and magnesia), or zirconia, make it possible to fabricate frameworks of various translucencies by using different processing techniques. This article discusses clinical indications and contraindications for the use of In-Ceram Alumina and In-Ceram Spinell all-ceramic restorations. Particular attention is given to cement considerations using several clinical examples.
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Óxido de Alumínio/uso terapêutico , Porcelana Dentária/uso terapêutico , Ligas Metalo-Cerâmicas/uso terapêutico , Óxido de Alumínio/química , Contraindicações , Coroas , Colagem Dentária/métodos , Porcelana Dentária/química , Facetas Dentárias , Prótese Parcial Fixa , Estética Dentária , Humanos , Seleção de Pacientes , Pigmentação em PróteseRESUMO
The use of photography is becoming a standard for today's modern dental practice. Dental imaging is critical for the sharing of visual information among the patient, dentist, and ceramist. This article covers the basics of camera, lens, and flash selection, and the use of camera flash systems. It will also provide guidelines for obtaining a good dental image.
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Fotografia Dentária/instrumentação , Fotografia Dentária/métodos , Humanos , IluminaçãoRESUMO
A technique for the fabrication of copy milled ceramic restorations has been presented. Both direct and indirect fabrication techniques of inlays, onlays, veneers, and crowns are possible. A copy milling machine can mill accurately fitting restorations with a marginal gap of 50 microns. The machine uses premanufactured porcelain blanks, which have improved physical properties over conventional porcelains used in standard techniques. Recently, the ability to mill In-Ceram crowns from presintered alumina blocks and Spinell crowns from alumina/magnesia blocks has been added to the system. The copings are veneered with aluminous porcelain as in the conventional In-Ceram technique.
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Restauração Dentária Permanente/métodos , Óxido de Alumínio , Coroas , Porcelana Dentária , Restauração Dentária Permanente/instrumentação , Facetas Dentárias , Humanos , Restaurações Intracoronárias , Fatores de TempoRESUMO
Due to the limitations of current shade-matching systems, shade communication has proven inadequate. Techniques for the fabrication of porcelain crowns that match the natural definition must address numerous factors. While all-ceramic restorations are indicated for the rehabilitation of the anterior dentition, these modalities are problematic in the restoration of teeth with discolored substrates. This article presents a systematic procedure for the three-dimensional fabrication of porcelain restorations. Techniques for building porcelain and altering the translucency of ceramic cores are also presented.
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Óxido de Alumínio , Coroas , Porcelana Dentária , Planejamento de Prótese Dentária , Dente Pré-Molar , Humanos , Incisivo , Ligas Metalo-Cerâmicas , Pigmentação em Prótese , Descoloração de Dente/terapiaRESUMO
Metal-ceramic restorations remain the most widely accepted type of indirect restorative modality, and have been applied successfully for years. Recent advances in material science have resulted in the development of a new class of metal-ceramic materials that have been termed lower-fusing ceramics. Following proper procedures for preparation and metal framework design, these metal-ceramic porcelains achieve the aesthetics normally demonstrated by conventional all-ceramic restorations. This article provides an overview of the clinical and laboratory processes utilizing these materials and is illustrated by two case presentations.
Assuntos
Planejamento de Dentadura , Prótese Parcial Fixa , Ligas Metalo-Cerâmicas , Adulto , Idoso , Cimentação , Porcelana Dentária , Feminino , Ligas de Ouro , Humanos , MasculinoRESUMO
The increased demand for metal-free restorative alternatives has resulted in the proliferation of all-ceramic systems. While these materials can predictably achieve aesthetic results in the anterior, they have traditionally been contraindicated for posterior applications due to the greater stresses present in the region. This article discusses a zirconia/alumina-based ceramic system that has been developed to expand the alternatives for the aesthetic restoration of the dentition. Material properties and considerations for its use in crown restorations, fixed partial dentures, and custom implant abutments are similarly addressed.
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Coroas , Porcelana Dentária/química , Planejamento de Prótese Dentária , Prótese Parcial Fixa , Óxido de Alumínio , Dente Pré-Molar , Dente Suporte , Ligas Dentárias/química , Prótese Dentária Fixada por Implante , Vidro , Humanos , Dente Molar , ZircônioRESUMO
Restorative materials and techniques are constantly refined in order to address the aesthetic expectations of patients. Second-generation laboratory-fabricated composite materials have recently been developed to combine the advantages of porcelain with composite resin. This class of biomaterial can be utilized in a variety of direct and indirect clinical applications than include inlay/onlay restorations, full-coverage crowns, fixed partial dentures, and implant-supported prostheses. This article reviews considerations for the use of these materials from clinical indications through cementation.