Different effects of whitening treatment on natural teeth and teeth treated with Icon resin: an experimental study in vitro.

BACKGROUND: It is quite common for white spots to develop on a tooth, due sometimes to a defective formation of the enamel layer, and sometimes to patches of demineralisation as a result of poor oral hygiene during orthodontic treatment with fixed braces. ICON DMG is currently the only noninvasive treatment for white spots. After a preliminary etching, it infiltrates the enamel, filling the spaces between the prisms with a resinous material that has a refraction coefficient very similar to that of healthy tooth enamel. The aim of this study was to test the efficacy of professional whitening procedures on teeth previously treated with ICON. The study hypothesis was that infiltration with ICON resin creates a barrier capable of preventing the bleaching action of the whitening agent. MATERIALS: White spots were artificially created on one half of the vestibular surface of 12 human teeth, while the other half was protected with a composite adhesive. The white spots were infiltrated with ICON and the protective adhesive was subsequently removed. A professional teeth whitening procedure was then completed on both halves of the teeth. A statistical analysis was performed to compare spectrophotometric recordings obtained before and after the ICON infiltration and teeth whitening procedures. CONCLUSION: The whitening procedure modified the colour of the teeth on the half not infiltrated with ICON (p<0.05), but there was no statistically significant change in colour on the half infiltrated with ICON. The presence of the ICON resin seems to act as a partial barrier to the action of the whitening agent.

KCTD1 is a new modulator of the KCASH family of Hedgehog suppressors.

The Sonic Hedgehog (Hh) signal transduction pathway plays a critical role in many developmental processes and, when deregulated, may contribute to several cancers, including basal cell carcinoma, medulloblastoma, colorectal, prostate, and pancreatic cancer. In recent years, several Hh inhibitors have been developed, mainly acting on the Smo receptor. However, drug resistance due to Smo mutations or non-canonical Hh pathway activation highlights the need to identify further mechanisms of Hh pathway modulation. Among these, deacetylation of the Hh transcription factor Gli1 by the histone deacetylase HDAC1 increases Hh activity. On the other end, the KCASH family of oncosuppressors binds HDAC1, leading to its ubiquitination and subsequent proteasomal degradation, leaving Gli1 acetylated and not active. It was recently demonstrated that the potassium channel containing protein KCTD15 is able to interact with KCASH2 protein and stabilize it, enhancing its effect on HDAC1 and Hh pathway. KCTD15 and KCTD1 proteins share a high homology and are clustered in a specific KCTD subfamily. We characterize here KCTD1 role on the Hh pathway. Therefore, we demonstrated KCTD1 interaction with KCASH1 and KCASH2 proteins, and its role in their stabilization by reducing their ubiquitination and proteasome-mediated degradation. Consequently, KCTD1 expression reduces HDAC1 protein levels and Hh/Gli1 activity, inhibiting Hh dependent cell proliferation in Hh tumour cells. Furthermore, analysis of expression data on publicly available databases indicates that KCTD1 expression is reduced in Hh dependent MB samples, compared to normal cerebella, suggesting that KCTD1 may represent a new putative target for therapeutic approaches against Hh-dependent tumour.

2D/3D accuracies of implant position after guided surgery using different surgical protocols: A retrospective study.

PURPOSE: To compare the 2D and 3D positional accuracy of four guided surgical protocols using an analysis of linear and angular deviations. METHODS: DICOM and .STLs files obtained from a CBCT and a digital impression were superimposed with software to plan implant position. Fifty-six patients were subdivided into 4 groups: FGA group (template support [Ts]: teeth [T]; bed preparation [Bp]: fully guided [FG]; implant insertion [Ii]: 3D template [3Dt]; device [D]: manual adapter [MA], FGM group (Ts: T; Bp: FG; Ii: 3Dt; D: fully guided mounter [FGM]), PG group (Ts: T; Bp: FG; Ii: manual; D: none) and MS group (Ts: mucosa; Bp: FG; Ii: 3Dt; D: FGM). The position of 120 implants was assessed by superimposing the planned and final position recorded with a digital impression. RESULTS: In FGA group, 3D deviations were 0.92 ± 0.52 mm at the implant head and 1.14 ± 0.54 mm at the apex, and the angular deviation (ang. dev.) was 2.45 ± 1.24°. In FGM group, were 0.911 ± 0.44 mm (head) and 1.11 ± 0.54 mm (apex), and the ang. dev. was 2.73 ± 1.96°. In PG group, were 0.95 ± 0.47 mm (head) and 1.17 ± 0.488 mm (apex), and the ang. dev. was 3.71 ± 1.67°. In MS group, were 1.15 ± 0.45 mm (head) and 1.42 ± 0.45 mm (apex), and the ang. dev. was 4.19 ± 2.62°. Ang. dev. of MS group was different from the other groups (P < 0.05). CONCLUSIONS: Guided surgery showed a sufficient accuracy.

Implant-abutment connections on single crowns: a systematic review.

Different implant-abutment connections have been developed in the effort of reducing mechanical and biological failure. The most frequent complications are screw loosening, abutment or implant fracture and marginal bone loss due to overload and bacterial micro-leakage. Ideal connection should work as a one-piece implant avoiding the formation of a micro-gap at the implant-abutment interface. Different in vitro and in vivo researches have been published to compare the implant-abutment connections actually available: external hexagon, internal hexagon and conical finding different amount of micro-gap, micro-leakage and marginal bone loss. The aim of this article is to describe, according to the most recent literature, different kind of fixture-abutment connections and their clinical and mechanical advantages or disadvantages.

In vitro evaluation of prosthodontic impression on natural dentition: a comparison between traditional and digital techniques.

OBJECTIVES: The aim of this in vitro study is to evaluate the marginal and internal fit of zirconia core crowns manufactured following different digital and traditional workflows. METHODS: A 6° taper shoulder prepared abutment tooth was used to produce 20 zirconia core crowns using four different scanning techniques: scanned directly with the extraoral lab scanner, scanned with intraoral scanner, dental impressions using individual dental tray and polyether, dental casts from a polyether impressions. Marginal and internal fits were evaluated with digital photography and the silicone replica method. RESULTS: Medium marginal gaps were 76,00 µm ± 28.9 for extraoral lab scanner, 80.50 µm ± 36,2 for intraoral scanner, 88.10 µm ± 34,8 for dental impression scan and 112,4 µm ± 37,2 for dental cast scan. Medium internal gaps were 23.20 µm ± 10,3 for extraoral lab scanner, 16.20 µm ± 8.3 for intraoral scanner, 27.20 µm ± 16.7 for dental impression scan and 30.20 µm ± 12.7 for dental cast scan. CONCLUSION: Internal gap were extensively lower than 70 µm described in literature. Marginal fit was higher than ideal values for all the techniques but within the limit of clinical success. Intraoral scanners obtained the best results for internal gap.

Tamarins: Insights into monogamous and non-monogamous single female social and breeding systems.

Tamarins are reported to live in small multimale-multifemale groups characterized by a single breeding female. Here we present information on the composition and genetic relatedness of individuals in 12 wild-trapped groups of Weddell's saddleback tamarins (Saguinus weddelli) from northern Bolivia to determine if groups are best described as nuclear or extended families suggesting social monogamy or whether groups contain several unrelated same sex adults indicative of social polyandry/polygyny. Mean group size was 6.25 including an average of 2.16 adult males (range 1-4) and 2.08 adult females (1-3). No group contained only one adult male and one adult female and 25% of groups contained two parous females. We estimated the genetic relatedness among individuals using 13 polymorphic microsatellite markers. Across the population, mean relatedness was low and not significantly different among adult males versus among adult females, suggesting that both sexes disperse from their natal groups. Adults of both sexes also tended to have close same-sex adult relatives within their groups; relatedness among adult females of the same group averaged 0.31 and among adult males was 0.26. This suggests that tamarins of one or both sexes sometimes delay dispersal and remain as adults in their natal group or that emigration of same-sexed relatives into the same group may be common. Finally, parentage analyses indicated that, whereas the parents of juveniles generally were present in the group, this was not always the case. Based on these data, published reports of the presence of multiple breeding males and occasionally multiple breeding females in the same group, and the fact that less than 10% of groups in the wild contain a single adult male-adult female pair, we argue that social polyandry best characterizes the composition of tamarin groups and that monogamy is not a common mating pattern in Saguinus weddelli or other tamarin species.

Long-term decline of the Amazon carbon sink.

Atmospheric carbon dioxide records indicate that the land surface has acted as a strong global carbon sink over recent decades, with a substantial fraction of this sink probably located in the tropics, particularly in the Amazon. Nevertheless, it is unclear how the terrestrial carbon sink will evolve as climate and atmospheric composition continue to change. Here we analyse the historical evolution of the biomass dynamics of the Amazon rainforest over three decades using a distributed network of 321 plots. While this analysis confirms that Amazon forests have acted as a long-term net biomass sink, we find a long-term decreasing trend of carbon accumulation. Rates of net increase in above-ground biomass declined by one-third during the past decade compared to the 1990s. This is a consequence of growth rate increases levelling off recently, while biomass mortality persistently increased throughout, leading to a shortening of carbon residence times. Potential drivers for the mortality increase include greater climate variability, and feedbacks of faster growth on mortality, resulting in shortened tree longevity. The observed decline of the Amazon sink diverges markedly from the recent increase in terrestrial carbon uptake at the global scale, and is contrary to expectations based on models.

X-ray crystallographic and kinetic investigations of 6-sulfamoyl-saccharin as a carbonic anhydrase inhibitor.

6-Sulfamoyl-saccharin was investigated as an inhibitor of 11 α-carbonic anhydrase (CA, EC 4.2.1.1) isoforms of human (h) origin, hCA I-XIV, and X-ray crystallographic data were obtained for its adduct with hCA II, the physiologically dominant isoform. This compound possesses two potential zinc-binding groups, the primary sulfamoyl one and the secondary, acylatedsulfonamide. Saccharin itself binds to the Zn(II) ion from the CA active site coordinating with this last group, in deprotonated (SO2N(-)CO) form. Here we explain why 6-sulfamoyl-saccharin, unlike saccharin, binds to the metal ion from the hCA II active site by its primary sulfonamide moiety and not the secondary one as saccharin itself. Our study is useful for shedding new light to the structure-based drug design of isoform-selective CA inhibitors of the sulfonamide type.

Fully versus partially covered self-expandable metal stents in benign esophageal strictures.

Self-expandable plastic stents are currently recommended for refractory benign esophageal strictures but they show disappointing results in terms of migration and long-term efficacy. We report here our experience in the management of benign esophageal strictures with partially covered (PCSEMS) and fully covered self-expandable metal stents (FCSEMS). We performed a retrospective analysis of self-expandable metal stent (SEMS) placements for benign esophageal strictures from 1998 to 2011 in Rouen University Hospital. Twenty-two patients (15 men, 7 women) attempted 40 esophageal SEMS placements (17 PCSEMS, 23 FCSEMS) during this period. All technical complications were migrations. Migration was noted after 3/17 PCSEMS (17.6%) and 4/23 FCSEMS placement (17.4%, P = ns). Clinical complications occurred after 6/17 PCSEMS and 2/23 FCSEMS placements (35.3% vs. 8.7%, P = 0.053). PCSEMS caused two major complications (fistulae) whereas FCSEMS did not cause any major complication (11.7% vs. 0%). Mean dysphagia score was significantly lower after SEMS placement (1.68 vs. 3.08, P < 0.001) with similar results for PCSEMS and FCSEMS. Stent placement resulted in long-term clinical success for 23.5% of PCSEMS and 34.7% of FCSEMS (P = 0.0505). FCSEMS provide satisfying clinical success rate with an acceptable complication rate and they could constitute a relevant therapeutic option in the management of benign esophageal strictures.

Evaluation of three different manual techniques of sharpening curettes through a scanning electron microscope: a randomized controlled experimental study.

OBJECTIVE: The purpose of this study was to compare the effectiveness of three different techniques for manually sharpening of periodontal curettes (PCs) by examining the blades with the aid of scanning electron microscope (SEM). METHODS: Three groups were considered based on three sharpening methods used: group A (moving a PC over a stationary stone); group B (moving a stone over a stationary PC) and group C (moving a PC over a stone fixed, placed on a 'sharpening horse'). After the sharpening, the blades were examined using SEM. The SEM images were assessed independently by five different independent observers. An evaluation board was used to assign a value to each image. A preliminary pilot study was conducted to establish the number of samples. Pearson's correlation test was used to assess the correlations between measurements. anova test with Bonferroni's post hoc test was used to compare the three groups. RESULTS: Sixty PCs (20 PCs per group) were used in this study. Statistically significant differences emerged between the three groups (P-value = 0.001). Bonferroni's test showed that the difference between groups A and B was not statistically significant (P-value = 0.80), while it was significant for the comparisons between groups A and C (P-value = 0.005) and between groups B and C (P-value = 0.001). CONCLUSIONS: The sharpening technique used in group C, which involved the use of the sharpening horse, proved the most effective.

[Thyroid Phylogeny: from seaweeds to man]. / Filogenesi della tiroide: dalle alghe all'uomo.

Iodine uptake and production of iodine-aminoacids are evolutionarily very old phenomena. Seaweed are the first eukaryotic organism presenting these functions; they are rich in iodine and are at basis of the food chain. The monoiodotirosines, precursors of thyroxine, have been identified in a wide variety of invertebrates, such as Gorgonians and Tunicates. The structure of the thyroid appears for the first time in Cyclostomes adults (Lamprey), while in Tunicates (Ciona intestinalis) and Amphioxus is present a similar structure, the endostyle, which is an invagination of the ventral wall of the pharynx containing glandular cells that are able to concentrate iodine. This is not a true endocrine gland because the secretion is poured into the alimentary canal. In the larva of Lamprey (Ammocoetes) during the metamorphosis some of the epithelial cells persist and transform in the follicles. The cyclostomes, therefore, represent a link between the endostyle of protochordates and the thyroid gland of higher chordates. This hypothesis is confirmed by molecular genetic studies which have demonstrated the expression of Thyroid Transcription Factor (TTF-1) in the endostyle of Ciona, Lamprey and Amphioxus. The TTF-1 is an ancestral transcription factor which controls the survival of thyroid follicular cells at the beginning of organogenesis and regulates the expression of thyroid-specific genes in adult life.

Yield and impact of emergency capsule enteroscopy in severe obscure-overt gastrointestinal bleeding.

BACKGROUND AND STUDY AIMS: Patients with obscure-overt gastrointestinal bleeding (OOGIB) are defined by overt hemorrhage and negative upper and lower endoscopy findings. At present, the place of emergency capsule enteroscopy in patients with severe OOGIB is unknown. The aim of this study was to assess the diagnostic yield and the impact of emergency capsule enteroscopy on further management in patients with severe OOGIB. PATIENTS AND METHODS: Between 2003 and 2010, we retrospectively included all patients with severe OOGIB who underwent emergency capsule enteroscopy in the 24-48 h following negative urgent upper and lower endoscopy. Severe OOGIB was defined by ongoing bleeding with hemodynamic instability and/or the need for significant red blood cell transfusion. RESULTS: Out of 5744 patients hospitalized in our Gastrointestinal Bleeding Unit, 55 (1%) presented with severe OOGIB and underwent emergency capsule enteroscopy. Capsule enteroscopy showed blood in 41 patients (75%) and lesions in 37 patients (67%). Findings included small bowel angiodysplasia in 19 patients (35%), ulcers in 7 (13%), tumors in 5 (9%), small-bowel varices in 2 (3%), cecum angiodysplasia in 4 (7%), fresh blood in small bowel without identified lesion in 12 (22%). Specific diagnostic and therapeutic procedures were undertaken in 78 % of patients. Further management included endoscopy (54%), surgery (22%), and radiology (2%). CONCLUSIONS: Emergency capsule enteroscopy identified bleeding lesions in 67 % of patients with severe OOGIB. Emergency capsule enteroscopy seems to be a promising diagnostic tool with a subsequent impact on clinical management in patients with severe OOGIB.

[Management of patient with Gaves' orbitopathy]. / Gestione del paziente con orbitopatia di Graves.

Graves' orbitopathy (GO) is the most common and important extrathyroidal manifestation of Flajani-Basedow-Graves' disease, with autoimmune etiology. In most cases they are mild forms, in 3-5% they are severe and progressive. For therapeutic purposes, it is classified according to the severity (mild, moderate-severe or sight threatening), to the activity (active if clinical activity score is >=3), and to the impact on quality of life. The choice of medical or surgical therapy depends on the activity of the disease. Therapy for mild GO consists of abolition of risk factors, local treatments, oral administration of selenium. Therapy for moderate-severe and active GO consists of administration of intravenous, oral, topic and local (retrobulbar, peribulbar and subconjunctival) glucocorticoids (GC). The therapy of choice, after careful selection of patients, is pulse therapy with intravenous GC, with 79% of response. Orbital radiotherapy is effective in 60% of cases; diabetes mellitus and hypertension are absolute contraindications. Contemporary administration of oral GC and orbital radiotherapy are more effective than single therapies. Marginal and not validated therapies are cyclosporine, somatostatin analogues, TNF-a inhibitors and rituximab. The treatment for dysthyroid optic neuropathy (DON) consists of combination of steroids, orbital radiotherapy and, if necessary, orbital decompression surgery. The surgical therapies are orbital decompression and rehabilitative surgery.

Medical treatment of hyperthyroidism: state of the art.

Methimazole (MMI) and propylthiouracil (PTU) are the main antithyroid drugs used for hyperthyroidism. They inhibit the synthesis of thyroid hormone at various levels and are used as the primary treatment for hyperthyroidism or as a preparation before radioiodine therapy or thyroidectomy. MMI is the drug of choice because of its widespread availability, longer half-life and small number of severe side effects. Drugs of second choice are potassium perchlorate, beta blockers, iodine, lithium carbonate and glucocorticoids. Rituximab, a monoclonal antibody directed against human CD20, was recently proposed as a biological therapy for cases of Graves' disease unresponsive to traditional drugs.

Influence of estroprogestinic therapy on the postoperative course following impacted third molar extraction.

AIM: Female patients on estroprogestinic therapy undergoing extraction of the third lower molar have a higher incidence of postoperative complications (dry socket -DS- pain). The purpose of this study is to verify such data and analyse if there are risk factors for the appearance of other postoperative complications. METHODS: One hundred eighteen non-smoking healthy patients were included who underwent extraction of the impacted third lower molar (38 on oral contraceptives, OC, 80 as control). After the extraction, patients were prescribed with a pharmacological therapy, consisting of a per os antibiotic and antiseptic rinse. Each patient was examined after 7 days following surgery to verify the state of tissues. In addition subjective postoperative pain (VAS - Visual Analogue Scale) and intake of analgesic drugs were recorded. RESULTS: One case of DS (2.64%) occurred in the OC group, and 1 case of DS occurred in control-patients group (1.25%) (P=0.4436). The postoperative pain proved significantly higher in OC compared to control (first and fifth postoperation day). In OC a predisposition to dehiscence of the wound (86.84% P=0.0021) and emergence of laterocervical lymphadenitis (81.57% P=0.0010) was found, while no cases of postextractive abscesses and trismus of the masseter were found. CONCLUSION: Although no correlation between DS and estroprogestinic therapy has been found, a more difficult healing of tissues has been observed as well as a significantly higher subjective pain index in the postoperative days considered in OC patients.

[Antithyroid drugs therapy]. / Terapia con farmaci antitiroidei.

Methimazole and Propylthiouracil are the cornerstones in the management of Graves' disease. Their primary effect is to inhibit thyroid hormone synthesis at different steps, i.e. in thyroid gland and in peripheral tissues. Antithyroid drugs can be used as the primary treatment for hyperthyroidism (long term therapy: 1-2 years) or as preparative therapy before radioiodine treatment or surgery (short term therapy: weeks or months). Generally, the starting dose of methimazole is 10-30 mg, as single daily dose, while that of PTU is 100-300 mg every 6 hours. Methimazole is the drug of choice, because major side effects are less common, it can be used as single dose, it's less expensive and more available. As far as the treatment of hyperthyroidism in pregnancy, MMI and PTU have same therapeutic efficacy and are both safe for the fetus, having similar placental transfer kinetics. The use of methimazole can be associated with aplasia cutis and choanal/esophageal atresia, while there are no data supporting the association between congenital anomalies and PTU. For this reason the latter is the drug of choice in the treatment of hyperthryroidism in pregnancy. Both thionamides are present in breast milk, but there are no controindications for their use during lactation.

The estimation of the thyroid volume before surgery--an important prerequisite for minimally invasive thyroidectomy.

INTRODUCTION: Actually, thyroid volume >25 ml, obtained by preoperative ultrasound evaluation, is a very important exclusion criteria for minimally invasive thyroidectomy. So far, among different imaging techniques, two-dimensional ultrasonography has become the more accepted method for the assessment of thyroid volume (US-TV). The aims of this study were: (1) to estimate the preoperative thyroid volume in patients undergoing minimally invasive total thyroidectomy using a mathematical formula and (2) to verify its validity by comparing it with the postsurgical TV (PS-TV). MATERIALS AND METHOD: In 53 patients who underwent minimally invasive total thyroidectomy (from January 2003 to December 2007), US-TV, obtained by ellipsoid volume formula, was compared to PS-TV determined by the Archimedes' principle. A mathematical formula able to predict the TV from the US-TV was applied in 34 cases in the last 2 years. RESULTS: Mean US-TV (14.4 +/- 5.9 ml) was significantly lower than mean PS-TV (21.7 +/- 10.3 ml). This underestimation was related to gland multinodularity and/or nodular involvement of the isthmus. A mathematical formula to reduce US-TV underestimation and predict the real TV was developed using a linear model. Mean predicted TV (16.8 +/- 3.7 ml) perfectly matched mean PS-TV, underestimating PS-TV in 19% of cases. We verified the accuracy of this mathematical model in patients' eligibility for minimally invasive total thyroidectomy, and we demonstrated that a predicted TV <25 ml was confirmed post-surgery in 94% of cases. CONCLUSIONS: We demonstrated that using a linear model, it is possible to predict from US the PS-TV with high accuracy. In fact, the mean predicted TV perfectly matched the mean PS-TV in all cases. In particular, the percentage of cases in which the predicted TV perfectly matched the PS-TV increases from 23%, estimated by US, to 43%. Moreover, the percentage of TV underestimation was reduced from 77% to 19%, as well as the range of the disagreement from up to 200% to 80%. This study shows that two-dimensional US can provide the accurate estimation of thyroid volume but that it can be improved by a mathematical model. This may contribute to a more appropriate surgical management of thyroid diseases.

Non-HDL cholesterol predicts coronary heart disease in primary prevention: findings from an Italian 40-69 year-old cohort in general practice.

OBJECTS: Non-HDL cholesterol is now recommended as an index of risk associated with combined dyslipidemia, and it has also been found useful in predicting coronary heart disease (CHD) risk in patients with diabetes. We studied the association between known CHD risk factors, enclosed non-HDL cholesterol, and a "high CHD risk condition", i.e. a "5-years CHD risk >15%" in general practice. METHODS: We studied 4,085 40-69 year-old diabetic (no. 489) and non-diabetic (no. 3,596) individuals from an opportunistic cohort. Cross-sectional descriptive statistics, and age- and gender-adjusted multiple logistic exponential betas have been calculated. RESULTS: About 12% of the participants had diabetes. Age- and gender-adjusted comparison showed that all the study variables were significantly worse in diabetic vs. non-diabetic individuals (except cigarette smoking, total blood cholesterol and the ratio of total to HDL cholesterol). They had a mean "5-year CHD-risk" significantly higher than non-diabetic individuals (18.8+/-11.9% vs 7.5+/-6.9%, P<0.01), and a four-fold prevalence of "5-years CHD risk >15%" (55.4% vs 11.1%, P<0.01). As to diabetic individuals, the study variables associated to a "high CHD risk condition" were cigarette smoking, systolic blood pressure, and non-HDL blood cholesterol levels. As to non-diabetic individuals cigarette smoking, systolic blood pressure, and HDL (inversely) and non-HDL blood cholesterol levels were associated to a "high CHD risk condition". CONCLUSIONS: Non-HDL cholesterol--and cigarette smoking and systolic blood pressure--strongly predicted a "high CHD risk condition" both in diabetic and non-diabetic individuals.

Pattern and process in Amazon tree turnover, 1976-2001.

Previous work has shown that tree turnover, tree biomass and large liana densities have increased in mature tropical forest plots in the late twentieth century. These results point to a concerted shift in forest ecological processes that may already be having significant impacts on terrestrial carbon stocks, fluxes and biodiversity. However, the findings have proved controversial, partly because a rather limited number of permanent plots have been monitored for rather short periods. The aim of this paper is to characterize regional-scale patterns of 'tree turnover' (the rate with which trees die and recruit into a population) by using improved datasets now available for Amazonia that span the past 25 years. Specifically, we assess whether concerted changes in turnover are occurring, and if so whether they are general throughout the Amazon or restricted to one region or environmental zone. In addition, we ask whether they are driven by changes in recruitment, mortality or both. We find that: (i) trees 10 cm or more in diameter recruit and die twice as fast on the richer soils of southern and western Amazonia than on the poorer soils of eastern and central Amazonia; (ii) turnover rates have increased throughout Amazonia over the past two decades; (iii) mortality and recruitment rates have both increased significantly in every region and environmental zone, with the exception of mortality in eastern Amazonia; (iv) recruitment rates have consistently exceeded mortality rates; (v) absolute increases in recruitment and mortality rates are greatest in western Amazonian sites; and (vi) mortality appears to be lagging recruitment at regional scales. These spatial patterns and temporal trends are not caused by obvious artefacts in the data or the analyses. The trends cannot be directly driven by a mortality driver (such as increased drought or fragmentation-related death) because the biomass in these forests has simultaneously increased. Our findings therefore indicate that long-acting and widespread environmental changes are stimulating the growth and productivity of Amazon forests.

Crystal structure of the dimeric unswapped form of bovine seminal ribonuclease.

Bovine seminal ribonuclease is a unique case of protein dimorphism, since it exists in two dimeric forms, with different biological and kinetic behavior, which interconvert into one another through three-dimensional swapping. Here we report the crystal structure, at 2.2 A resolution, of the unswapped form of bovine seminal ribonuclease. Besides completing the structural definition of bovine seminal ribonuclease conformational dimorphism, this study provides the structural basis to explain the dependence of the enzyme cooperative effects on its swapping state.