A multifunctional guided surgery to assist in the 3-dimensional positioning of dental implants and in obtaining a palatal gingival graft.

Parameters such as the correct 3-dimensional positioning and the quality of peri-implant soft tissues are fundamental to the success of implant-supported restorations. Digital planning and guided surgery techniques can make the implant placement more accurate, and modifying the periodontal phenotype is often fundamental to increasing esthetics and peri-implant health, mainly in esthetic areas. This article describes a guided surgery technique that assists in the 3-dimensional positioning of implants and identifies the best anatomic area (volume and safety) for obtaining a palatal gingival graft.

Gingival recession treatment with enamel matrix derivative associated with coronally advanced flap and subepithelial connective tissue graft: a split-mouth randomized controlled clinical trial with molecular evaluation.

OBJECTIVES: The goal of this study was to evaluate the impact of enamel matrix derivative (EMD) on periodontal healing after root coverage (RC) surgery, involving CAF in combination with SCTG, and to assess the molecular profile, verifying the inflammation level in early stage (1 and 2 weeks). MATERIALS AND METHODS: Thirty-two recessions (RT1) were submitted to periodontal surgery with (test) or without (control) EMD. The clinical parameters analyzed on the day of surgery and 6 months after the surgical procedure were as follows: recession height and width, keratinized tissue height, percentual root coverage, and the gingival thickness of keratinized tissue. Moreover, the main inflammatory biomarkers and growth factors (IL-1ß, IL-6, IL-8, FGF, MIP-1α and ß, PDGF, TNF-α, and VEGF) were evaluated at baseline, 7, and 14 days after procedures. RESULTS: The average root coverage was significantly higher in the test group as compared to the control group (86% vs. 66%, p = 0.008). The test side had significantly lesser final RH compared to the control side (p = 0.01). Also, there was a significant reduction of RW in both groups, with more significant results in the test group. KTH and GT were not significantly different at any time and group. After 14 days, the immunological analysis showed an increase of VEGF (p = 0.03) on the test group compared to the control side. CONCLUSION: The use of EMD in RC surgeries resulted in a significantly higher RC, as well as a significant increase in VEGF expression, suggesting that EMD may contribute to the angiogenic and healing process. CLINICAL RELEVANCE: EMD provided better results in root coverage treatment when associated with CAF and SCTG, beyond a greater releasing of angiogenic growth factor (VEGF), which enhanced the result.

The novel ghrelin receptor inverse agonist PF-5190457 administered with alcohol: preclinical safety experiments and a phase 1b human laboratory study.

Rodent studies indicate that ghrelin receptor blockade reduces alcohol consumption. However, no ghrelin receptor blockers have been administered to heavy alcohol drinking individuals. Therefore, we evaluated the safety, tolerability, pharmacokinetic (PK), pharmacodynamic (PD) and behavioral effects of a novel ghrelin receptor inverse agonist, PF-5190457, when co-administered with alcohol. We tested the effects of PF-5190457 combined with alcohol on locomotor activity, loss-of-righting reflex (a measure of alcohol sedative actions), and on blood PF-5190457 concentrations in rats. Then, we performed a single-blind, placebo-controlled, within-subject human study with PF-5190457 (placebo/0 mg b.i.d., 50 mg b.i.d., 100 mg b.i.d.). Twelve heavy drinkers during three identical visits completed an alcohol administration session, subjective assessments, and an alcohol cue-reactivity procedure, and gave blood samples for PK/PD testing. In rats, PF-5190457 did not interact with the effects of alcohol on locomotor activity or loss-of-righting reflex. Alcohol did not affect blood PF-5190457 concentrations. In humans, all adverse events were mild or moderate and did not require discontinuation or dose reductions. Drug dose did not alter alcohol concentration or elimination, alcohol-induced stimulation or sedation, or mood during alcohol administration. Potential PD markers of PF-5190457 were acyl-to-total ghrelin ratio and insulin-like growth factor-1. PF-5190457 (100 mg b.i.d.) reduced alcohol craving during the cue-reactivity procedure. This study provides the first translational evidence of safety and tolerability of the ghrelin receptor inverse agonist PF-5190457 when co-administered with alcohol. PK/PD/behavioral findings support continued research of PF-5190457 as a potential pharmacological agent to treat alcohol use disorder.

Biomarkers and genetic modulators of cerebral vasculopathy in sub-Saharan ancestry children with sickle cell anemia.

We investigated biomarkers and genetic modulators of the cerebral vasculopathy (CV) subphenotype in pediatric sickle cell anemia (SCA) patients of sub-Saharan African ancestry. We found that one VCAM1 promoter haplotype (haplotype 7) and VCAM1 single nucleotide variant rs1409419_T were associated with stroke events, stroke risk, as measured by time-averaged mean of maximum velocity in the middle cerebral artery, and with high serum levels of the hemolysis biomarker lactate dehydrogenase. Furthermore, VCAM-1 ligand coding gene ITGA4 variants rs113276800_A and rs3770138_T showed a positive association with stroke events. An additional positive relationship between a genetic variant and stroke risk was observed for ENPP1 rs1044498_A. Conversely, NOS3 variants were negatively associated with silent cerebral infarct events (VNTR 4b_allele and haplotype V) and CV globally (haplotype VII). The -alpha3.7kb-thal deletion did not show association with CV. However, it was associated with higher red blood cell and neutrophil counts, and lower mean corpuscular volume, mean corpuscular hemoglobin and red cell distribution width. Our results underline the importance of genetic modulators of the CV sub-phenotype and their potential as SCA therapeutic targets. We also propose that a biomarker panel comprising biochemical, hematological, imaging and genetic data would be instrumental for CV prediction, and prevention.

Effectiveness of connective tissue graft substitutes for the treatment of gingival recessions compared with coronally advanced flap: a network meta-analysis.

OBJECTIVES: This study aimed to conduct a network comparison of the clinical effect of connective tissue graft (CTG) substitutes on the treatment of gingival recessions using coronally advanced flap. MATERIALS AND METHODS: An electronic search without language or dates restrictions was performed in five databases and in Grey literature for articles published until May, 2020. The eligibility criteria comprised randomized controlled trials (RCTs) that analyzed the clinical outcomes of CTG substitutes when compared with coronally advanced flap (CAF) for the treatment of Miller class I and II (Cairo RT I) gingival recessions. A pairwise and network meta-analysis were conducted for each periodontal parameters to assess and compare the outcomes among different treatment arms for the primary and secondary outcomes. This systematic review (SR) was registered in INPLASY under number INPLASY202060075. RESULTS: Twenty-seven studies were included in the present SR. All analyzed CTG substitutes showed superior results when comparing with CAF alone for all periodontal parameters. However, when compared in a network, the acellular dermal matrix (ADM) demonstrated the best treatment ranking of probability results, followed by platelet-rich fibrin (PRF), enamel matrix derivative (EMD), and xenogeneic collagen matrix (XCM) for root coverage (RC). CONCLUSION: This SR observed that the association of biomaterials increases the effectiveness of RC in comparison with CAF alone. Based on the treatment ranking, although all the biomaterials analyzed showed a positive effect for RC, the ADM demonstrated the best results. CLINICAL RELEVANCE: To know the effectiveness of CTG substitutes for the treatment of gingival recessions.

Genetic modulators of fetal hemoglobin expression and ischemic stroke occurrence in African descendant children with sickle cell anemia.

Sickle cell anemia (SCA) is an autosomal recessive monogenic disease with significant clinical variability. Cerebrovascular disease, particularly ischemic stroke, is one of the most severe complications of SCA in children. This study aimed to investigate the influence of genetic variants on the levels of fetal hemoglobin (Hb F) and biochemical parameters related with chronic hemolysis, as well as on ischemic stroke risk, in ninety-one unrelated SCA patients, children of sub-Saharan progenitors. Our results show that a higher Hb F level has an inverse relationship with the occurrence of stroke, since the group of patients who suffered stroke presents a significantly lower mean Hb F level (5.34 ± 4.57% versus 9.36 ± 6.48%; p = 0.024). Furthermore, the co-inheritance of alpha-thalassemia improves the chronic hemolytic pattern, evidenced by a decreased reticulocyte count (8.61 ± 3.58% versus 12.85 ± 4.71%; p < 0.001). In addition, our findings have confirmed the importance of HBG2 and BCL11A loci in the regulation of Hb F expression in sub-Saharan African SCA patients, as rs7482144_A, rs11886868_C, and rs4671393_A alleles are significantly associated with a considerable increase in Hb F levels (p = 0.019, p = 0.026, and p = 0.028, respectively). Concerning KLF1, twelve different variants were identified, two of them novel. Seventy-three patients (80.2%) presented at least one variant in this gene. However, no correlation was observed between the presence of these variants and Hb F level, severity of hemolysis, or stroke occurrence, which is consistent with their in silico-predicted minor functional consequences. Thus, we conclude that the prevalence of functional KLF1 variants in a sub-Saharan African background does not seem to be relevant to SCA clinical modulation.

Genetic characterization of Portuguese allochthonous populations of Pinus nigra using ISSRs and SCoTs and extrapolation of their infraspecific taxonomy.

The Pinus nigra distribution in Portugal is restricted to six allochthonous populations with unknown origin and infraspecific taxonomy. This work intends to evaluate their genetic diversity, structure and relationships, and to infer about their infraspecific taxonomy by comparing molecular patterns produced by inter-simple sequence repeat and Start Codon Targeted markers among Portuguese and foreign samples with known taxonomy and provenance. 127 Portuguese P. nigra individuals were clustered per population. The genetic differentiation was higher within rather than among populations. The pooled molecular data indicated high genetic proximity among the Portuguese and foreign samples of subspecies laricio. However, the separate analysis per marker system demonstrated that two varieties of subspecies laricio (corsicana and calabrica) may have been used in the plantations of the Portuguese P. nigra stands performed in the last century. The genetic characterization and extrapolation of the intraspecific taxonomy of these populations provide useful information for forest management, afforestation and germplasm use.

Variants in the non-coding region of the TLR2 gene associated with infectious subphenotypes in pediatric sickle cell anemia.

Sickle cell anemia (SCA) is characterized by chronic hemolysis, severe vasoocclusive crises (VOCs), and recurrent often severe infections. A cohort of 95 SCA pediatric patients was the background for genotype-to-phenotype association of the patient's infectious disease phenotype and three non-coding polymorphic regions of the TLR2 gene, the -196 to -174 indel, SNP rs4696480, and a (GT)n short tandem repeat. The infectious subphenotypes included (A) recurrent respiratory infections and (B) severe bacterial infection at least once during the patient's follow-up. The absence of the haplotype [Del]-T-[n ≥ 17] (Hap7) in homozygocity protected against subphenotype (B), in a statistically significant association, resisting correction for multiple testing. For the individual loci, the same association tendencies were observed as in the haplotype, including a deleterious association between the SNP rs4696480 T allele and subphenotype (A), whereas the A/A genotype was protective, and a deleterious effect of the A/T genotype with subphenotype (B), as well as including the protective effect of -196 to -174 insert (Ins) and deleterious effect of the deletion (Del) in homozygocity, against subphenotype (B). Moreover, a reduction in the incidence rate of severe bacterial infection was associated to a rise in the hemolytic score, fetal hemoglobin levels (prior to hydroxyurea treatment), and 3.7-kb alpha-thalassemia. Interestingly, differences between the effects of the two latter covariables favoring a reduction in the incidence rate of subphenotype (B) contrast with a resulting increase in relation to subphenotype (A). These results could have practical implications in health care strategies to lower the morbidity and mortality of SCA patients.

PD-1 modulates steady-state and infection-induced IL-10 production in vivo.

Programmed death-1 (PD-1) plays an important role in mediating immune tolerance through mechanisms that remain unclear. Herein, we investigated whether PD-1 prevents excessive host tissue damage during infection with the protozoan parasite, Toxoplasma gondii. Surprisingly, our results demonstrate that PD-1-deficient mice have increased susceptibility to T. gondii, with increased parasite cyst counts along with reduced type-1 cytokine responses (IL-12 and IFN-γ). PD-1⁻/⁻ DCs showed no cell intrinsic defect in IL-12 production in vitro. Instead, PD-1 neutralization via genetic or pharmacological approaches resulted in a striking increase in IL-10 release, which impaired type-1-inflammation during infection. Our results indicate that the absence of PD-1 increases IL-10 production even in the absence of infection. Although the possibility that such increased IL-10 protects against autoimmune damage is speculative, our results show that IL-10 suppresses the development of protective Th1 immune response after T. gondii infection.

Effect of Functionally Significant Deiodinase Single Nucleotide Polymorphisms on Drinking Behavior in Alcohol Dependence: An Exploratory Investigation.

BACKGROUND: Abnormalities of the hypothalamic-pituitary-thyroid (HPT) axis have been reported in alcoholism; however, there is no definitive agreement on the specific thyroid abnormalities and their underlying mechanisms in alcohol dependence. The biological activity of thyroid hormones or the availability of T3 is regulated by the three deiodinase enzymes: D1, D2, and D3. In the context of alcohol use, functionally significant single nucleotide polymorphisms (SNPs) of these deiodinase genes may play a role in HPT dysfunction. METHODS: This study explored the effect of three functionally significant SNPs (D1: rs2235544, D2: rs225014, and rs12885300) of deiodinase genes on drinking behavior and thyroid-stimulating hormone (TSH) levels in alcohol-dependent (N = 521) and control subjects (N = 288). RESULTS: Rs225014 was associated with significant differences in the amount of naturalistic alcohol drinking assessed by Timeline Follow Back. Alcohol-dependent subjects had significantly higher TSH levels compared to controls; however, there was no effect of genotype on TSH levels for either group. CONCLUSIONS: These findings extend previous studies on thyroid dysfunction in alcoholism and provide novel, albeit preliminary, information by linking functionally significant genetic polymorphisms of the deiodinase enzymes with alcohol-drinking behavior.

Infiltrating S100A8+ myeloid cells promote metastatic spread of human breast cancer and predict poor clinical outcome.

The mechanisms by which breast cancer (BrC) can successfully metastasize are complex and not yet fully understood. Our goal was to identify tumor-induced stromal changes that influence metastatic cell behavior, and may serve as better targets for therapy. To identify stromal changes in cancer-bearing tissue, dual-species gene expression analysis was performed for three different metastatic BrC xenograft models. Results were confirmed by immunohistochemistry, flow cytometry, and protein knockdown. These results were validated in human clinical samples at the mRNA and protein level by retrospective analysis of cohorts of human BrC specimens. In pre-clinical models of BrC, systemic recruitment of S100A8+ myeloid cells-including myeloid-derived suppressor cells (MDSCs)-was promoted by tumor-derived factors. Recruitment of S100A8+ myeloid cells was diminished by inhibition of tumor-derived factors or depletion of MDSCs, resulting in fewer metastases and smaller primary tumors. Importantly, these MDSCs retain their ability to suppress T cell proliferation upon co-culture. Secretion of macrophage inhibitory factor (MIF) activated the recruitment of S100A8+ myeloid cells systemically. Inhibition of MIF, or depletion of MDSCs resulted in delayed tumor growth and lower metastatic burden. In human BrC specimens, increased mRNA and protein levels of S100A8+ infiltrating cells are highly associated with poor overall survival and shorter metastasis free survival of BrC patients, respectively. Furthermore, analysis of nine different human gene expression datasets confirms the association of increased levels of S100A8 transcripts with an increased risk of death. Recruitment of S100A8+ myeloid cells to primary tumors and secondary sites in xenograft models of BrC enhances cancer progression independent of their suppressive activity on T cells. In clinical samples, infiltrating S100A8+ cells are associated with poor overall survival. Targeting these molecules or associated pathways in cells of the tumor microenvironment may translate into novel therapeutic interventions and benefit patient outcome.

Genetic variation in CD36, HBA, NOS3 and VCAM1 is associated with chronic haemolysis level in sickle cell anaemia: a longitudinal study.

Chronic haemolysis stands out as one of the hallmarks of sickle cell anaemia, a clinically heterogeneous autosomal recessive monogenic anaemia. However, the genetic architecture of this sub-phenotype is still poorly understood. Here, we report the results of an association study between haemolysis biomarkers (serum LDH, total bilirubin and reticulocyte count) and the inheritance of 41 genetic variants of ten candidate genes in a series of 99 paediatric SS patients (median current age of 9.9 yr) followed up in two general hospitals in Greater Lisboa area (median follow-up per patient of 5.0 yr). Although in a large number of tests a seemingly significant (i.e. P < 0.05) association was observed, the following ones were confirmed upon correction for multiple comparisons: (i) an increased serum LDH level was associated with haplotype 7 within VCAM1 gene; (ii) a lower total bilirubin was associated with the 3.7-kb deletion at HBA gene, rs2070744_T allele at NOS3 gene, and haplotype 9 within VCAM1 promoter; and (iii) a diminished reticulocyte count was associated with the 3.7-kb deletion at HBA, whereas an increased count was associated with rs1984112_G allele at CD36 gene. On the whole, our findings suggest a complex genetic architecture for the sickle cell anaemia haemolysis process involving multiple pathways, namely control of vascular cell adhesion, NO synthesis and erythrocyte volume and haemoglobinisation.

Anti-inflammatory actions of lipoxin A4 and aspirin-triggered lipoxin are SOCS-2 dependent.

Control of inflammation is crucial to prevent damage to the host during infection. Lipoxins and aspirin-triggered lipoxins are crucial modulators of proinflammatory responses; however, their intracellular mechanisms have not been completely elucidated. We previously showed that lipoxin A4 (LXA4) controls migration of dendritic cells (DCs) and production of interleukin (IL)-12 in vivo. In the absence of LXA4 biosynthetic pathways, the resulting uncontrolled inflammation during infection is lethal, despite pathogen clearance. Here we show that lipoxins activate two receptors in DCs, AhR and LXAR, and that this activation triggers expression of suppressor of cytokine signaling (SOCS)-2. SOCS-2-deficient DCs are hyper-responsive to microbial stimuli, as well as refractory to the inhibitory actions of LXA4, but not to IL-10. Upon infection with an intracellular pathogen, SOCS-2-deficient mice had uncontrolled production of proinflammatory cytokines, decreased microbial proliferation, aberrant leukocyte infiltration and elevated mortality. We also show that SOCS-2 is a crucial intracellular mediator of the anti-inflammatory actions of aspirin-induced lipoxins in vivo.

Opposing biological functions of tryptophan catabolizing enzymes during intracellular infection.

Recent studies have underscored physiological and pathophysiological roles for the tryptophan-degrading enzyme indolamine 2,3-dioxygenase (IDO) in immune counterregulation. However, IDO was first recognized as an antimicrobial effector, restricting tryptophan availability to Toxoplasma gondii and other pathogens in vitro. The biological relevance of these findings came under question when infectious phenotypes were not forthcoming in IDO-deficient mice. The recent discovery of an IDO homolog, IDO-2, suggested that the issue deserved reexamination. IDO inhibition during murine toxoplasmosis led to 100% mortality, with increased parasite burdens and no evident effects on the immune response. Similar studies revealed a counterregulatory role for IDO during leishmaniasis (restraining effector immune responses and parasite clearance), and no evident role for IDO in herpes simplex virus type 1 (HSV-1) infection. Thus, IDO plays biologically important roles in the host response to diverse intracellular infections, but the dominant nature of this role--antimicrobial or immunoregulatory--is pathogen-specific.

Endodontic and Periodontal Treatment of Complete Buccal Root and Apex Exposition: A Challenging Case Report With 17 Months Follow-Up.

INTRODUCTION: This case report demonstrated a challenging clinical case addressed within a multidisciplinary approach to achieve its maintenance, even though had a poor prognosis. It was associated with the endodontic treatment with mucogingival techniques, including periodontal microsurgery and connective tissue graft. CASE PRESENTATION: A patient presented a deep gingival recession with the apex-exposed non-vital tooth with interproximal bone loss (RT2) and without mobility. The treatment involved an initial endodontic approach and periodontal therapy (scaling and root planing), microsurgical techniques with coronally advanced flap, root preparation with PrefGel (24% EDTA), enamel matrix derivatives (Emdogain), and connective tissue graft. As a clinical result, it was verified an increase of keratinized tissue width and gingival thickness, and root coverage (RC), reaching good esthetics and a stable result after 17 months. CONCLUSION: The correct diagnosis and technique selection may affect directly the outcome, especially in challenging cases. Even though there was a poor prognosis, an adequate treatment plan, patient cooperation, and technique mastery help to achieve a high level of RC, esthetic recovering, and successful outcome.

Clinical evaluation and biological understanding of the early step-by-step healing after periodontal microsurgery: A case report with PES analysis comparing initial and 31-day result.

Microsurgery has evolved, permitting faster vascularization and healing than macro-interventions, reducing tissue trauma and obtaining precise wound closure. Therefore, this study aimed to detail the initial healing steps after the periodontal microsurgical procedure. A -26 year-old female had a localized recession (anterior lower tooth, recession type1-), with the absence of local keratinized tissue width (KTW) and adjacent gingival thickness (GT)<1 mm. After oral prophylaxis and occlusal adjustments, the pink esthetic score was performed (5 points), followed by the microsurgery procedure. Prior to inserting the subepithelial connective tissue graft (SCTG), the epithelial layer was removed, and the root surface was biomodified. Two days postoperatively, it was possible to observe a white layer from the SCTG in the gingival margin, decreasing after 4 days. In 6 days, the sutures were removed; no graft and volume loss was observed. For 9 days, the volume was the maintenance. Nevertheless, there was a reduction in tissue volume in the facial zone. After 11 and 13 days, an improved healing process was found, whereas, after 16 days, it was possible to report stable tissues, which was confirmed after 31 days, with a significant GR reduction and an increase in KTW and GT. Moreover, the final pink esthetic score (PES) was 9. Microsurgery had a faster healing and predictable outcome, suggesting reduced trauma, which may allow a quicker suture removal without jeopardizing the outcomes.

Use of Botulinum Toxin Before Surgical Lip Repositioning: A Randomized Clinical Trial.

This study aimed to determine whether administering botulinum toxin type A (BT) prior to surgery would stabilize surgical lip repositioning. A randomized controlled parallel-group clinical trial was performed. A total of 18 participants with excessive gingival display (EGD) were divided into two groups. For the test group (TG), BT was injected into the smile muscle locations 15 days before the surgical procedure. For the control group (CG), only lip repositioning surgery was performed. Gingival display (GD) and upper lip displacement (LD) were measured 3 and 6 months postoperatively. Data were submitted to ANOVA, Tukey, and t tests. For GD and LD, the changes were statistically significant between the measurements taken at the baseline, 3-month, and 6-month marks. The GD presented a reduction of 5.2 ± 1.1 mm in TG and 3.2 ± 1.4 mm in CG after 6 months. The LD measurements reduced 45% for TG and 26% for CG in 6 months. The injection of BT 15 days before lip repositioning surgery provided more stable results and effectively reduced the GD at 6 months.

Histologic and histomorphometric analysis of connective tissue grafts harvested by the parallel incision method: a pilot randomized controlled trial comparing macro- and microsurgical approaches.

OBJECTIVE: The aim of this pilot randomized controlled trial was to assess the efficacy of macro- and microsurgical procedures in removing the epithelial tissue layer of subepithelial connective grafts (SCTGs) harvested by the parallel incision method. METHOD AND MATERIALS: Sixteen patients were randomized to receive macro-SCTG harvesting (n = 10, control group) or micro-SCTG harvesting (n = 10, test group) by the parallel incision technique. Histologic and histomorphometric analysis of the SCTG evaluated the percentage remnant of epithelium and connective tissue. The presence of remnant portions of the epithelium was identified in eight samples (three in the macro- and five in the microsurgery groups). RESULTS: Sixteen participants with 20 sites were included and 20 SCTG were collected and analyzed. SCTG harvested by microsurgical approaches displayed more portions of remnant epithelium compared to the conventional removal (50% versus 30%). There were no significant differences in mean remnant epithelial thickness for test (147.3 ± 89.3 µm) and control (209.0 ± 127.5 µm) groups (P = .57). Likewise, nonsignificant differences were identified in terms of the connective tissue thickness (macrosurgery: 1,511.0 ± 1,160.0 µm; microsurgery: 1,472.0 ± 1,063.0 µm) between groups (P = .96). CONCLUSION: The samples harvested by microsurgery had greater remaining epithelial portions than those harvested by macrosurgery, and similar connective layer thickness.

Seed Germination in Cistus ladanifer: Heat Shock, Physical Dormancy, Soil Temperatures and Significance to Natural Regeneration.

Seeds of Cistus ladanifer experience bursts of germination following fires. The effects of heat shock from 10 °C to 150 °C on seed germination were investigated by final germination plus the number of days required for germination to start and finish, and symmetry of cumulative germination. The occurrence of physical dormancy in C. ladanifer seeds was investigated by a variety of methods, including imbibition, scanning electron microscopy (SEM) and light microscopy, and use of dyes. The significance of responses of C. ladanifer seeds to fires was investigated essentially by abstracting existing literature and by using fire effects models and simulations. Parameters of germination were variously affected by heat treatments-positively in the range 80⁻100 °C, negatively above 130 °C. Non-dormancy was consistently found in about 30% of seeds but no evidence was obtained to support the existence of physical dormancy in the dormant fraction of C. ladanifer seeds. Two complementary processes seem to be in place in seeds response to fire. A direct fire-driven increase in germination of virtually all seeds in response to the appropriate heat load produced by fire or, in the absence of such heat loads, the germination of the non-dormant fraction provided that above-ground vegetation burns.

Modeling size-number distributions of seeds for use in soil bank studies.

Knowledge of soil seed banks is essential to understand the dynamics of plant populations and communities and would greatly benefit from the integration of existing knowledge on ecological correlations of seed size and shape. The present study aims to establish a feasible and meaningful method to describe size-number distributions of seeds in multi-species situations. For that purpose, size-number distributions of seeds with known length, width and thickness were determined by sequential sieving. The most appropriate combination of sieves and seeds dimensions was established, and the adequacy of the power function and the Weibull model to describe size-number distributions of spherical, non-spherical, and all seeds was investigated. We found that the geometric mean of seed length, width and thickness was the most adequate size estimator, providing shape-independent measures of seeds volume directly related to sieves mesh side, and that both the power function and the Weibull model provide high quality descriptions of size-number distributions of spherical, non-spherical, and all seeds. We also found that, in spite of its slightly lower accuracy, the power function is, at this stage, a more trustworthy model to characterize size-number distributions of seeds in soil banks because in some Weibull equations the estimates of the scale parameter were not acceptable.