Six hundred years of South American tree rings reveal an increase in severe hydroclimatic events since mid-20th century.

South American (SA) societies are highly vulnerable to droughts and pluvials, but lack of long-term climate observations severely limits our understanding of the global processes driving climatic variability in the region. The number and quality of SA climate-sensitive tree ring chronologies have significantly increased in recent decades, now providing a robust network of 286 records for characterizing hydroclimate variability since 1400 CE. We combine this network with a self-calibrated Palmer Drought Severity Index (scPDSI) dataset to derive the South American Drought Atlas (SADA) over the continent south of 12°S. The gridded annual reconstruction of austral summer scPDSI is the most spatially complete estimate of SA hydroclimate to date, and well matches past historical dry/wet events. Relating the SADA to the Australia-New Zealand Drought Atlas, sea surface temperatures and atmospheric pressure fields, we determine that the El Niño-Southern Oscillation (ENSO) and the Southern Annular Mode (SAM) are strongly associated with spatially extended droughts and pluvials over the SADA domain during the past several centuries. SADA also exhibits more extended severe droughts and extreme pluvials since the mid-20th century. Extensive droughts are consistent with the observed 20th-century trend toward positive SAM anomalies concomitant with the weakening of midlatitude Westerlies, while low-level moisture transport intensified by global warming has favored extreme rainfall across the subtropics. The SADA thus provides a long-term context for observed hydroclimatic changes and for 21st-century Intergovernmental Panel on Climate Change (IPCC) projections that suggest SA will experience more frequent/severe droughts and rainfall events as a consequence of increasing greenhouse gas emissions.

Displaced proximal humeral fractures: when is surgery necessary?

BACKGROUND: Several therapeutic methods have been traditionally used in the treatment of displaced proximal humeral fractures; however, the indication of these treatments is still controversial. The purpose of this study was to compare the medium-term functional results of four methods commonly used in the treatment of proximal humeral fractures [conservative treatment, proximal humeral nails (PHN), percutaneous K-wiring (PKW), and locking-plates (LP)] taking into consideration the type of fracture and the age of the patients. METHODS: We conducted a retrospective cohort study on patients with proximal humeral fractures treated with one of the following methods: conservative treatment, PHN, PKW, or LP. Functional results were assessed using the absolute Constant score and the disabilities of the arm shoulder and hand score (DASH). The functional outcome was analysed according to age (≥65 years and <65 years) and fracture type (displaced 2-fragment and 3-4-fragment fractures). RESULTS: A total of 113 patients were included in the study, with a mean age of 65.3 SD 15.2 years and average follow-up time of 26.2 SD 12.6 months. Patients under 65 years had higher Constant scores when treated with PHN and PKW than those treated conservatively (77.2 vs. 54.7, p=0.01 and 74.0 vs. 54.7, p=0.03, respectively). Patients above 65 years had higher Constant scores when treated with PKW compared to PHN and conservative treatment (68.7 vs. 51.9, p=0.02 and 68.7 vs. 55.9, p=0.029, respectively). In 2-fragment fractures, PKW resulted in higher Constant scores than conservative treatment (70.4 vs. 53.9, p=0.048). No differences were found in the final outcome between patients treated with LP and those treated conservatively regardless of age, and fracture type. There were also no differences between any of the evaluated methods in the treatment of 3-4-fragment fractures. CONCLUSION: The use of PKW was associated with better functional results than conservative treatment in individuals of all ages, especially in patients with 2-fragment fractures; PKW also achieved better functional results than PHN in elderly patients. PHN was superior to conservative treatment in young individuals. No significant differences were found between LP and conservative treatment in any of the analysed categories.

Acetylcholinesterase inhibitors and the risk of hip fracture in Alzheimer's disease patients: a case-control study.

Recent studies have reported the presence of acetylcholine (ACh) receptor subtypes in bone tissue, and have demonstrated that inhibition of the ACh receptors has negative effects on bone mass and fracture healing capacity. However, little is known about the potential clinical effects that increased ACh signaling might have on bone. Accordingly, this study was designed to determine whether the use of acetylcholinesterase inhibitors (AChEIs), a group of drugs that stimulate ACh receptors and are used to treat Alzheimer's disease (AD), is associated with a decreased risk of hip fracture in AD patients. To accomplish this objective, a case-control analysis was performed using the AD population, aged above 75 years, based in the local health area of the Carlos Haya Hospital, in Malaga, Spain. The cases were 80 AD patients that suffered a hip fracture between January 2004 and December 2008. The controls were 2178 AD patients without hip fracture followed at our health care area during the same period of time. Compared with patients who did not use AChEIs, the hip fracture adjusted odds ratio (OR) for users of AChEIs was 0.42 (95% confidence interval [CI], 0.24-0.72), for users of rivastigmine was 0.22 (95% CI, 0.10-0.45), and for users of donepezil was 0.39 (95% CI, 0.19-0.76). Data were adjusted for the following parameters: body mass index, fall risk, smoking habits, cognition, dependence, degree of AD, comorbidity score, treatment with selective serotonin reuptake inhibitors, age, and gender. Our data suggests that use of AChEIs donepezil and rivastigmine is associated with a reduced risk of fractures in AD patients. Many elderly patients with AD disease who are at risk of developing osteoporosis may potentially benefit from therapy with the AChEIs donepezil and rivastigmine.