TuMV triggers stomatal closure but reduces drought tolerance in Arabidopsis.

Compatible plant viral infections are a common cause of agricultural losses worldwide. Characterization of the physiological responses controlling plant water management under combined stresses is of great interest in the current climate change scenario. We studied the outcome of TuMV infection on stomatal closure and water balance, hormonal balance and drought tolerance in Arabidopsis. TuMV infection reduced stomatal aperture concomitantly with diminished gas exchange rate, daily water consumption and rosette initial dehydration rate. Infected plants overaccumulated salicylic acid and abscisic acid and showed altered expression levels of key ABA homeostasis genes including biosynthesis and catabolism. Also the expression of ABA signalling gene ABI2 was induced and ABCG40 (which imports ABA into guard cells) was highly induced upon infection. Hypermorfic abi2-1 mutant plants, but no other ABA or SA biosynthetic, signalling or degradation mutants tested abolished both stomatal closure and low stomatal conductance phenotypes caused by TuMV. Notwithstanding lower relative water loss during infection, plants simultaneously subjected to drought and viral stresses showed higher mortality rates than mock-inoculated drought stressed controls, alongside downregulation of drought-responsive gene RD29A. Our findings indicate that despite stomatal closure triggered by TuMV, additional phenomena diminish drought tolerance upon infection.

Osteonecrosis of the jaws in patients assuming oral bisphosphonates for osteoporosis: a retrospective multi-hospital-based study of 87 Italian cases.

BACKGROUND: Bisphosphonates (BPs) are currently the chief drugs for the prevention/treatment of osteoporosis; one of their adverse effects is the osteonecrosis of the jaw (BRONJ). The primary endpoints of this multi-center cross-sectional study are: i) an observation of the clinical features of BRONJ in 87 osteoporotic, non-cancer patients; and ii) an evaluation of their demographic variables and comorbidities. METHODS: 87 BRONJ patients in therapy for osteoporosis with BPs from 8 participating clinical Italian centers were consecutively identified and studied. After BRONJ diagnosis and staging, comorbidities and data relating to local and drug-related risk factors for BRONJ were collected. RESULTS: 77/87 (88.5%) patients in our sample used alendronate as a BP type; the duration of bisphosphonate therapy ranged from 2 to 200 months, and 51.7% of patients were in treatment for ≤ 38 months (median value). No comorbidities or local risk factors were observed in 17 (19.5%) patients, indicating the absence of cases belonging to BRONJ forms triggered by surgery. BRONJ localization was significantly associated with age: an increased risk of mandible localization (p=0.002; OR=6.36, 95%CI=[1.89; 21.54]) was observed for those over 72 yrs. At multivariate analysis, the increased risk of BRONJ in the mandible for people over 72 yrs (OR'=6.87, 95%CI=[2.13; 2.21]) was confirmed for a BP administration >56 months (OR'=4.82, 95%CI=[2.13; 22.21]). CONCLUSION: Our study confirms the fundamental necessity of applying protocols of prevention in order to reduce the incidence of BRONJ in osteoporotic, non-cancer patients in the presence of comorbidities and/or local risk factor as well as, less frequently, in their absence.

Resective surgical approach shows a high performance in the management of advanced cases of bisphosphonate-related osteonecrosis of the jaws: a retrospective survey of 347 cases.

PURPOSE: The aim of this study was to evaluate the results of the surgical treatment of bisphosphonate-related osteonecrosis of the jaw (BRONJ) in a large cohort. MATERIALS AND METHODS: A retrospective cohort multicenter study was designed. Patients were enrolled if they were diagnosed with BRONJ and received operative treatment. Data on demographic, health status, perioperative, and surgical factors were collected retrospectively. The primary outcome variable was a change in BRONJ staging (improvement, worsening, or no change). Interventions were grouped by local debridement and resective surgery. Data were collected for other variables as cofactors. Univariate analysis and logistic regressions were then performed. RESULTS: Of the 347 BRONJ-affected subjects, 59% showed improvement, 30% showed no change, and 11% showed worsening. Improvement was observed in 49% of cases treated with local debridement and 68% of cases treated with resective surgery. Multivariate analysis indicated that maxillary location, resective surgery, and no additional corticosteroid treatment were associated with a positive outcome. CONCLUSIONS: Surgical treatment of BRONJ appeared to be more effective when resective procedures were performed. Nonetheless, other factors, such as the absence of symptoms and the types of drug administration, should be taken into account before clinical decisions are made.

Surgery-triggered and non surgery-triggered Bisphosphonate-related Osteonecrosis of the Jaws (BRONJ): A retrospective analysis of 567 cases in an Italian multicenter study.

Invasive local procedures are often reported in clinical history of patients suffering from Bisphosphonates-Related Osteonecrosis of the Jaws (BRONJ) but over 40% of spontaneous forms have been also described in literature. We compared age, gender, underlying bone disorders, bisphosphonate therapy, clinical features and surgical outcome of 205 cases (36.2%) of BRONJ non surgery-triggered (group 1) with 362 (63.8%) cases of surgery-triggered forms (group 2). Differences between group 1 and 2 were analysed using Mann-Whitney U and χ(2) tests. Statistical analysis was performed using STATA 8. Zoledronate was the most used type of bisphosphonate (63.4% versus 69.0%) and the mandible was the most frequently involved site (63.9% versus 63.4%) in both groups. BRONJ in group 1 was more frequently multicentric (9.3% versus 5%, p<0.05), had a lower clinical stage (45.9% versus 13.8% in stage 1, p<0.01) and had a better outcome after surgical therapy (improvement in 74.1% versus 58.6%, p<0.05). The high prevalence of non surgery-triggered forms of BRONJ should be considered by oncologists, haematologists and general physicians who are advised to inform their patients regarding the importance of preventive dental protocols to control the possible causes of osteonecrosis not related to dental invasive procedures.