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.

Systemic lupus erythematosus is not a risk factor for poor outcomes after total hip and total knee arthroplasty.

OBJECTIVES: Historically, arthroplasty in systemic lupus erythematosus (SLE) patients has been less successful than for patients with osteoarthritis (OA). It is not known if SLE remains an independent risk factor for poor arthroplasty outcomes or if other factors, such as avascular necrosis (AVN), continue to play a role. METHODS: A case-control study using data from a single-institution arthroplasty registry compared SLE total hip arthroplasty (THA) and total knee arthroplasty (TKA) with OA controls matched by age, gender and presence of AVN. Baseline, two-year administrative and self-report data, and diagnosis leading to arthroplasty were evaluated. RESULTS: A total of 54 primary SLE THA and 45 primary SLE TKA were identified from May 2007 through June 2011. AVN was present in 32% of SLE THA and no TKA. SLE THA had worse preoperative WOMAC pain (42.5 vs. 52.7; p = 0.01) and function (38.8 vs. 48.0; p = 0.05) compared with OA. However, at two years there was no difference in WOMAC pain (91.1 vs. 92.1; p = 0.77) or WOMAC function (86.4 vs. 90.8; p = 0.28). SLE TKA were similar to OA in both preoperative pain (42.6 vs. 48.4; p = 0.14) and function (42.1 vs. 46.8; p = 0.30) and two-year pain (85.7 vs. 88.6; p = 0.50) and function (83.7 vs. 85.1; p = 0.23). Compared to OA, SLE THA and TKA patients had more renal failure (14% vs. 1%; p = 0.007) and hypertension (52% vs. 29%; p = 0.009). In a multivariate linear regression, SLE was not predictive of either poor pain or poor function. CONCLUSIONS: While SLE patients have more comorbidities than OA, and SLE THA have worse preoperative pain and function compared with OA controls, SLE was not an independent risk factor for poor short-term pain or function after either hip or knee arthroplasty.

Pregabalin and pain after total knee arthroplasty: a double-blind, randomized, placebo-controlled, multidose trial.

BACKGROUND: Pregabalin may reduce postoperative pain and opioid use. Higher doses may be more effective, but may cause sedation and confusion. This prospective, randomized, blinded, placebo-controlled study tested the hypothesis that pregabalin reduces pain at 2 weeks after total knee arthroplasty, but increases drowsiness and confusion. METHODS: Patients (30 per group) received capsules containing pregabalin (0, 50, 100, or 150 mg); two capsules before surgery, one capsule twice a day until postoperative day (POD) 14, one on POD15, and one on POD16. Multimodal analgesia included femoral nerve block, epidural analgesia, oxycodone-paracetamol, and meloxicam. The primary outcome was pain with flexion (POD14). RESULTS: Pregabalin did not reduce pain at rest, with ambulation, or with flexion at 2 weeks (P=0.69, 0.23, and 0.90, respectively). Pregabalin increased POD1 drowsiness (34.5, 37.9, 55.2, and 58.6% in the 0, 50, 100, and 150 mg arms, respectively; P=0.030), but did not increase confusion (0, 3.5, 0, and 3.5%, respectively; P=0.75). Pregabalin had no effect on acute or chronic pain, opioid consumption, or analgesic side-effects. Pregabalin reduced POD14 patient satisfaction [1-10 scale, median (first quartile, third quartile): 9 (8, 10), 8 (7, 10), 8 (5, 9), and 8 (6, 9.3), respectively; P=0.023). Protocol compliance was 63% by POD14 (50.0, 70.0, 76.7, and 56.7% compliance, respectively), with no effect of dose on compliance. Per-protocol analysis of compliant patients showed no effect of pregabalin on pain scores. CONCLUSIONS: Pregabalin had no beneficial effects, but increased sedation and decreased patient satisfaction. This study does not support routine perioperative pregabalin for total knee arthroplasty patients. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov: http://www.clinicaltrials.gov/ct2/show/study/NCT01333956.

Cementless versus cemented unicompartmental knee arthroplasty: a systematic review of comparative studies.

There are still some controversies regarding the clinical use of cementless UKAs. The aim of this systematic review was to determine whether cementless medial UKA leads to similar outcomes compared to cemented medial UKA. This search was conducted in accordance with the Preferred Reporting Items for Systematic Reviews guidelines (PRISMA). The random effects model with 95% confidence interval (CI) was applied to the analysis. The I2 statistic was used to assess study heterogeneity. Six studies were eligible for inclusion (4784 UKAs, 4776 patients): 2947 cemented UKAs (61.6%) and 1837 cementless UKAs (38.4%). The overall mean follow-up was 4.9 years. The all-cause reoperation rate was 11.3% (80 of 706) at mean 5.7-year follow-up for cemented UKA and 6.9% (57 of 824) at mean 4.1-year follow-up for the cementless. The overall revision rate was 10.2% (303 of 2947) for the cemented and 5.8% (108 of 1837) for the cementless. Aseptic loosening was the most frequent reason of revision (2.3% cemented vs 0.5% cementless). The overall rate of radiolucent lines (RLL) was 28.3% (63 of 223) in the cemented cohort and 11.1% in the cementless (26 of 234). All the studies reported improved functional outcomes. Cementless UKA provides at least equivalent if not better results compared to cemented UKA. Despite the use of cemented UKA outnumber cementless fixation, available data shows that cementless UKA had a reduced midterm revision rate, while providing similar functional outcomes.

The clinical outcome of chondrolabral-preserving arthroscopic acetabuloplasty for pincer- or mixed-type femoroacetabular impingement: A systematic review.

While preservation and repair of the acetabular labrum are increasingly being recognized as important goals in hip arthroscopy, controversies still exist regarding the clinical outcome of arthroscopic acetabuloplasty with chondrolabral preservation. A systematic review was conducted and implemented by two independent reviewers, who used the MEDLINE/PubMed database and the Cochrane Database of Systematic Reviews for their search. These databases were queried with the terms "arthroscopic acetabuloplasty" and "chondrolabral preservation" and "arthroscopic acetabular recession." From the 55 initial studies the reviewers finally chose and assessed five clinical studies which were eligible to their inclusion-exclusion criteria. The reviewed studies included in total 444 patients, mainly young, between 30 and 40 years old. The follow-up evaluation varied between 24 and 41 months, while all studies utilized at least a 24-month final end-point assessment. All five studies illustrated improved outcome with the use of chondrolabral preservation acetabuloplasty without labral detachment. The rate of complications was very low. The different techniques of arthroscopic acetabuloplasty combined with chondrolabral preservation illustrated encouraging results in patients suffering from pincer-type or mixed-type FAI. However, the available clinical evidence was limited and insufficient to establish any superiority of these techniques over the traditional labral detachment and sequential reattachment. In relation to the optimal treatment of FAI without isolated CAM, further research of higher quality is recommended to be conducted in order to lead to definitive conclusions.

Characterization of opioid consumption and disposal patterns after total knee arthroplasty.

AIMS: The aim of this study was to determine the general postoperative opioid consumption and rate of appropriate disposal of excess opioid prescriptions in patients undergoing primary unilateral total knee arthroplasty (TKA). PATIENTS AND METHODS: In total, 112 patients undergoing surgery with one of eight arthroplasty surgeons at a single specialty hospital were prospectively enrolled. Three patients were excluded for undergoing secondary procedures within six weeks. Daily pain levels and opioid consumption, quantity, and disposal patterns for leftover medications were collected for six weeks following surgery using a text-messaging platform. RESULTS: Overall, 103 of 109 patients (94.5%) completed the daily short message service (SMS) surveys. The mean oral morphine equivalents (OME) consumed during the six weeks post-surgery were 639.6 mg (sd 323.7; 20 to 1616) corresponding to 85.3 tablets of 5 mg oxycodone per patient. A total of 66 patients (64.1%) had stopped taking opioids within six weeks of surgery and had the mean equivalent of 18 oxycodone 5 mg tablets remaining. Only 17 patients (25.7%) appropriately disposed of leftover medications. CONCLUSION: These prospectively collected data provide a benchmark for general opioid consumption after uncomplicated primary unilateral TKA. Many patients are prescribed more opioids than they require, and leftover medication is infrequently disposed of appropriately, which increases the risk for illicit diversion. Cite this article: Bone Joint J 2019;101-B(7 Supple C):98-103.

Decision making in rheumatoid arthritis. Determining surgical priorities.

Consideration of the individual, his or her needs, and what he or she hopes to gain through surgery is of primary importance in determining a surgical plan for the rheumatoid patient. Nevertheless, procedures undertaken to save life or prevent neurologic demise must, of course, take precedence. Alleviation of pain and correction of disabling deformity take next priority. Many other considerations go into the formulation of the list of surgical priorities. A full understanding of these considerations and a well-integrated team approach to the rheumatoid patient provide the best chance for optimal outcome following surgery.

The double-stemmed silicone-rubber implant for rheumatoid arthritis of the first metatarsophalangeal joint. Long-term results.

Sixty-seven feet in forty-five patients who had rheumatoid arthritis were followed for an average of six years (range, four to ten years) after an operation on the forefoot that included resection of the metatarsophalangeal heads or joints and the insertion of a double-stemmed silicone-rubber implant in the first metatarsophalangeal joint. There were forty-two women and three men, and the average age at the time of the operation was fifty-six years (range, thirty-six to seventy-nine years). The mean duration of known rheumatoid arthritis was fifteen years (range, three to thirty-seven years). Resection of the metatarsophalangeal heads or joints was performed through a plantar approach in forty-one feet and a dorsal approach in twenty-six feet. A double-stemmed silicone-rubber implant was placed in the first metatarsophalangeal joint in all feet. Each patient was evaluated clinically and radiographically with use of a foot-scoring system that was developed for this study. The results were assessed for relief of pain, ability to walk (including the use of shoes), presence of calluses or deformity, and radiographic findings. The average preoperative foot score was 47 points; the score had improved to an average of 81 points at the latest follow-up examination. A good or excellent result was obtained in fifty-eight feet (87 per cent). Complications were infrequent. In three feet, there was delayed healing of the wound; three implants were removed because of dislocation and infection; and four feet had revision to correct deformities of the lesser toes.

Histomorphometric analysis of vertebral and iliac crest bone samples. A correlated study.

Iliac crest and corresponding second vertebral body specimens were obtained from 20 cadavers. Of these, ten underwent histopathologic evaluation and histomorphometry in a blind fashion followed by statistical evaluation of the results. In this study, the authors found the iliac crest biopsy specimens to be highly correlated and predictive of osteoid and resorptive parameters in the spine and less so for trabecular bone volume. Whereas the transileal bone biopsy is a useful tool in diagnosing and typing metabolic bone disease, its predictive value of bone volume at other sites in the skeleton requires further evaluation.

Management of selected problems in revision knee arthroplasty.

In discussing revision arthroplasty, understanding the failure mode is essential to success. In general there are five major categories that one must address in assessing the failed knee replacement: Infection, mechanical problems, extensor mechanism dysfunction, fractures adjacent to the components, and skin problems. These five areas are discussed in this article.

Determining surgical priorities in rheumatoid arthritis.

Rheumatoid arthritis often affects multiple joints simultaneously with pain, deformity and loss of function. The indications for surgical treatment are presented along with guidelines for determining the surgical priorities along with guidelines for determining the surgical priorities when multiple joints require surgery.

Reducing blood loss after total knee replacement: a fibrin solution.

Blood loss during total knee replacement (TKR) remains a significant concern. In this study, 114 patients underwent TKR, and were divided into two groups based on whether they received a new generation fibrin sealant intra-operatively, or a local infiltration containing adrenaline. Groups were then compared for mean calculated total blood volume (TBV) loss, transfusion rates, and knee range of movement. Mean TBV loss was similar between groups: fibrin sealant mean was 705 ml (281 to 1744), local adrenaline mean was 712 ml (261 to 2308) (p = 0.929). Overall, significantly fewer units of blood were transfused in the fibrin sealant group (seven units) compared with the local adrenaline group (15 units) (p = 0.0479). Per patient transfused, significantly fewer units of blood were transfused in the fibrin sealant group (1.0 units) compared with the local adrenaline group (1.67 units) (p = 0.027), suggesting that the fibrin sealant may reduce the need for multiple unit transfusions. Knee range of movement was similar between groups. From our results, it appears that application of this newer fibrin sealant results in blood loss and transfusion rates that are low and similar to previously applied fibrin sealants.

Subsets of retinal progenitors display temporally regulated and distinct biases in the fates of their progeny.

Cell fate determination in the developing vertebrate retina is characterized by the sequential generation of seven classes of cells by multipotent progenitor cells. Despite this order of genesis, more than one cell type is generated at any time; for example, in the rat, several cell types are born during the prenatal period, while others are born postnatally. In order to examine whether there are classes of progenitor cells with distinct developmental properties contributing to this developmental progression, we examined antigen expression in progenitor cells during rat retinal development. Two markers of amacrine and horizontal cells, the VC1.1 epitope and syntaxin, were found to be expressed on a subset of progenitors in a temporally regulated manner that closely paralleled the birthdays of these cell types. In order to investigate which cell types were produced by the progenitors expressing these markers, fluorescent latex microspheres covalently coupled to VC1.1 antibodies were used to indelibly label VC1.1+ progenitor cells and their progeny. Early in retinal development, VC1.1+ progenitors generated a high percentage of amacrine and horizontal cells, but no cone photoreceptors. During this same period, a comparable number of cone photoreceptors were generated by VC1.1- progenitors. In the late embryonic and early postnatal period, VC1.1+ progenitors continued to generate predominantly amacrine cells, but also gave rise to an increasing number of rod photoreceptors. These findings demonstrate that expression of these two markers by progenitors is highly correlated with a bias towards the production of amacrine and horizontal cells. The fact that subsets of progenitors with temporally regulated and distinct biases are intermingled within the retinal neuroepithelium provides a basis for understanding how different cell types are generated both simultaneously and in a particular order by multipotent progenitors during retinal development.

Quantitative analysis of proliferation and cell cycle length during development of the rat retina.

The rat retina has been a useful model system for the study of the development of the central nervous system (CNS). In order to facilitate future studies on the mechanisms that control retinal growth, we have quantified the proliferation of retinal cells and the length of the cell cycle throughout development. For each day during development, the number of mitotic and postmitotic cells per retina, the proportion of cycling cells, S phase length, and cell cycle length were determined through quantification of cell numbers and 3H-thymidine labeling. As retinal development proceeds, the proportion of cycling cells decreases, and cell cycle length increases, in part due to an increase in S phase length.

Prospective study of porous-coated anatomic total hip arthroplasty.

Seventy-five uncemented porous-coated total hip prostheses were implanted in 64 patients. The results were reviewed after a mean follow-up period of 47 months (range, 40-64 months). The mean preoperative rating was fair, and the mean postoperative rating was excellent. There were six dislocations. Ten patients had mild thigh pain at one year; by two years, the pain had resolved in six patients. Neither moderate nor severe limp nor significant loosening of beads was observed. Only one patient had progressive radiolucent lines. The high rate of dislocation may be related to a compromise of acetabular position to obtain bony fixation in acetabula early in the series. The clinical results were encouraging.

Cell fate determination in the vertebrate retina.

In the vertebrate central nervous system, the retina has been a useful model for studies of cell fate determination. Recent results from studies conducted in vitro and in vivo suggest a model of retinal development in which both the progenitor cells and the environment change over time. The model is based upon the notion that the mitotic cells within the retina change in their response properties, or "competence", during development. These changes presage the ordered appearance of distinct cell types during development and appear to be necessary for the production of the distinct cell types. As the response properties of the cells change, so too do the environmental signals that the cells encounter. Together, intrinsic properties and extrinsic cues direct the choice of cell fate.

Short-term results of the M2a-taper metal-on-metal articulation.

A polyethylene-free, metal-on-metal acetabular system (M2a-taper [Biomet, Inc., Warsaw, IN]) was designed in an effort to improve total hip arthroplasty (THA) longevity. Minimum 2-year follow-up results involving 72 polyethylene liner THAs and 78 metal liner THAs from a multicenter, randomized, controlled, investigational device exemption study are reported. Mean Harris hip scores of 95.54 (polyethylene liner group) and 95.23 (metal liner group) were reported at mean follow-up intervals of 3.29 and 3.23 years. Radiographic evaluation revealed no evidence of early failure. No acetabular components have been revised or are pending revision. No statistically significant differences in the data were calculated between liner types except for the immediate postoperative (P=.0415) and minimum 2-year follow-up (P=.0341) angles of inclination. The M2a-taper metal-on-metal articulation may represent a viable alternative for THA in younger, higher demand patients.

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.