Quantifying the biodiversity value of tropical primary, secondary, and plantation forests.

Biodiversity loss from deforestation may be partly offset by the expansion of secondary forests and plantation forestry in the tropics. However, our current knowledge of the value of these habitats for biodiversity conservation is limited to very few taxa, and many studies are severely confounded by methodological shortcomings. We examined the conservation value of tropical primary, secondary, and plantation forests for 15 taxonomic groups using a robust and replicated sample design that minimized edge effects. Different taxa varied markedly in their response to patterns of land use in terms of species richness and the percentage of species restricted to primary forest (varying from 5% to 57%), yet almost all between-forest comparisons showed marked differences in community structure and composition. Cross-taxon congruence in response patterns was very weak when evaluated using abundance or species richness data, but much stronger when using metrics based upon community similarity. Our results show that, whereas the biodiversity indicator group concept may hold some validity for several taxa that are frequently sampled (such as birds and fruit-feeding butterflies), it fails for those exhibiting highly idiosyncratic responses to tropical land-use change (including highly vagile species groups such as bats and orchid bees), highlighting the problems associated with quantifying the biodiversity value of anthropogenic habitats. Finally, although we show that areas of native regeneration and exotic tree plantations can provide complementary conservation services, we also provide clear empirical evidence demonstrating the irreplaceable value of primary forests.

Hoverfly (syrphidae) communities respond to varying structural retention after harvesting in canadian peatland black spruce forests.

Variable retention harvesting (VRH), in which trees are removed at variable intensity and spatial configuration across the landscape, retains greater forest structural heterogeneity than traditional clear-cut harvesting and is being recommended as an alternative for sustainable management of the boreal forest. Little is known about its effects on forest fauna; thus, we studied the influence of one type of VRH (harvesting with advanced regeneration [HARP]) on the Syrphidae (Diptera) community in northern Ontario forests of peatland black spruce (Picea mariana). We examined the effects of varying structural retention (from unharvested through partial retention to clear-cut) on syrphid species richness and abundance, and abundance of functional assemblages. Greater species richness and population abundances were found generally in harvested than in unharvested forests. Overall species richness and the abundance of four species (Platycheirus rosarum, Toxomerus marginatus, Xylota annulifera, and X. tuberculata) and larval predators were all higher in both clear-cut sites and those with structural retention than in unharvested sites. Similarly, overall species richness and the abundance of nine species were higher in clear-cut than in unharvested sites. Species responses are discussed in an ecological context. Differences among the levels of forest retention harvesting were relatively minor compared with those of the clear-cut and unharvested area, suggesting that local habitat characteristics may play a more important role in determining the syrphid community than the landscape configuration. However, a landscape level effect was evident, suggesting that syrphids may be useful in reflecting changes in stand structure at the landscape scale.

Differences between forest type and vertical strata in the diversity and composition of hymenopteran families and mymarid genera in northeastern temperate forests.

Most insects' assemblages differ with forest type and show vertical stratification. We tested for differences in richness, abundance and composition of hymenopteran families and mymarid genera between sugar maple (Acer saccharum) and white pine (Pinus strobus) stands and between canopy and understory in northeastern temperate forests in Canada. We used flight interception traps (modified malaise traps) suspended in the canopy and the understory in a split-split block design, with forest type as the main factor, forest stratum as the first split factor, and collection bottle location as the second split factor. Hymenopteran families and mymarid genera differed in their diversity depending on forest type and stratum. Both family and genera richness were higher in maple than in pine forests, whereas family richness was higher in the canopy and top bottles and generic richness was higher in the understory and bottom bottles. Multivariate analysis separated samples by forest type, vegetation stratum, and bottle location. Family composition showed 77% similarity between forest types and 73% between the canopy and understory. At the lower taxa level, mymarid genera showed only 47% similarity between forest types and 40% between forest strata, indicating vertical stratification and relatively high beta-diversity. Our study suggests that hymenopteran diversity and composition is strongly dependent on forest type and structure, making flying members of this order particularly vulnerable to forest management practices. It also shows that insect assemblage composition (especially at low-taxon levels), rather than relative abundance and richness, is the community attribute most sensitive to forest type and vertical stratification.

A prospective randomized comparison of Medtronic Mosaic and Carpentier-Edwards-SAV in the aortic position: an interim report.

BACKGROUND AND AIM OF THE STUDY: The study aim was to compare prospectively the clinical performance and long-term durability of the Medtronic Mosaic and Carpentier-Edwards porcine (CE-SAV) bioprostheses in the aortic position over 10 years. METHODS: Between January 2001 and July 2003, a total of 242 patients undergoing bioprosthetic aortic valve replacement (AVR) were prospectively randomized to receive either Medtronic Mosaic (n = 126) or CE-SAV (n = 116) valves, and followed up annually. RESULTS: The mean follow up period was 1.7 +/- 0.8 years; total follow up was 411 patient-years. Early mortality and 40-month actuarial survival were 5.5% and 93 +/- 1% for the Mosaic valve, and 2.6% and 90 +/- 1% for the CE-SAV. Among patients, 78% showed symptomatic improvement in their NYHA functional class after AVR. To date there have been no structural failures, and one patient required reoperation for prosthetic valve (Mosaic) endocarditis. Early thromboembolic events occurred in 2.9% of patients (two Mosaic, five CE-SAV). Echocardiographic evaluations between the two valves demonstrated comparable hemodynamic performance for a given size at one year after surgery. CONCLUSION: At this stage of the study there were no differences in clinical or hemodynamic outcome in patients undergoing AVR using either the Mosaic or CE-SAV porcine xenograft.

Single-layer versus multiple-layer closure of leg wounds after long saphenous vein harvest: a prospective randomized trial.

BACKGROUND: The long saphenous vein harvested by traditional techniques is an important conduit for coronary artery bypass grafting (CABG). The purpose of this study was to determine if a single-layer closure over a drain improved wound healing compared with the traditional two-layer closure after harvest. METHODS: Seventy-eight consecutive patients undergoing CABG were prospectively randomized to have their leg wound closed by either a single-layer technique with a suction drain or multiple layers. All wounds were assessed using the additional treatment, presence of serous discharge, erythema, purulent exudate, and separation of the deep tissues, isolation of bacteria, and the duration of inpatient stay (ASEPSIS) score postoperatively and 6 weeks later. RESULTS: Forty-four patients (5 females) had their wound closed by the single-layer technique and 34 (6 females) closed in multiple layers. The ASEPSIS scores were significantly lower (p = 0.001) in those patients closed with a single layer (mean, 4.4) than those with multiple layers (mean, 6.8). Patients whose legs were closed with the single-layer technique had less peripheral edema compared with the multiple-layer group (chi2, p < 0.001). Using univariate analysis there was no correlation between ASEPSIS scores and length of wound incision (p = 0.49), whereas increasing age was found to have a weak positive correlation (r =0.24; p = 0.04). CONCLUSIONS: Single-layer leg wound closure over a suction drain is superior to the traditional multiple-layer closure. A possible mechanism of better wound healing in the former technique might be through decreased tissue handling and a reduction in leg edema.

Safety and efficacy of perioperative cell salvage and autotransfusion after coronary artery bypass grafting: a randomized trial.

BACKGROUND: The aim of this study was to ascertain whether cell salvage and autotransfusion after first time elective coronary artery bypass grafting is associated with a significant reduction in the use of homologous blood, a clinically significant derangement of postoperative clotting profiles, or an increased risk of postoperative bleeding. METHODS: Patients were randomized to autotransfusion (n = 98) receiving autotransfused washed blood from intraoperative cell salvage and postoperative mediastinal fluid cell salvage after coronary artery bypass surgery or control (n = 102) receiving stored homologous blood only after coronary artery bypass surgery. RESULTS: There was no statistical difference between the groups in terms of demographics, comorbidity, risk stratification, or operative details. Mean volume of blood autotransfused was 367 +/- 113 mL. Patients in the autotransfusion group were significantly less likely to receive a homologous blood transfusion compared with controls (odds ratio 0.40, 95% confidence interval [CI] 0.22-0.71) and received significantly fewer units of blood per patient compared with controls (0.43 +/- 1.5 vs 0.90 +/- 2.0 U, p = 0.02). There was no difference between the groups in terms of postoperative blood loss, fluid requirements, blood product requirements, or in the incidence of adverse clinical events (p = NS chi(2)). Autotransfusion did not produce any significant derangement of thromboelastograph values or laboratory measures of clotting pathway function (prothrombin time, activated partial thromboplastin time, fibrinogen, and fibrinogen D-dimer levels) when compared with the effect of homologous blood transfusion (p = NS, repeated measures analysis of variance [MANOVA]). CONCLUSIONS: Autotransfusion is a safe and effective method of reducing the use of homologous bank blood after routine first time coronary artery bypass grafting.

Risk of reoperation for structural failure of aortic and mitral tissue valves.

BACKGROUND AND AIM OF THE STUDY: The study aim was to assess the risk of reoperation for patients with a failing stented tissue valve. METHODS: Between 1980 and 1999, 259 patients (118 males, 141 females; mean age 60.1+/-15.4 years) underwent redo valve replacement to replace a failing stented tissue valve. Of these patients, 94 (36.3%) underwent redo aortic valve replacement (AVR), 105 (40.5%) redo mitral valve replacement (MVR), and 60 (23.2%) redo aortic and mitral valve replacement (DVR). Twenty patients (7.7%) had previous coronary artery bypass grafting (CABG); further CABG were performed in 32 cases (12.4%). Preoperatively, 216 patients (83.3%) were in NYHA functional class III or IV. RESULTS: The early mortality was (6.5%; n = 17), including three patients who had AVR, five DVR, and nine MVR. A higher preoperative NHYA status (p <0.0004) and emergency surgery (p <0.0001) were significantly associated with an increased risk of operative death (univariate analysis). Age at surgery (p = 0.45), previous CABG (p = 0.45), position of the valve replaced (p = 0.2), type of implant (p = 0.06) and presence of coronary artery disease (p = 0.51) were not associated with a significant risk of operative mortality. Including those patients who died, 88 (34.0%) experienced a peri- or postoperative complication, seven of which (2.7%) were permanent. CONCLUSION: A failing tissue valve can be replaced, with acceptable operative mortality and morbidity. The choice of valve is a balance of its advantages and disadvantages, and these must be discussed with the patient. It appears, however, that the trend towards reducing the age at which tissue valve implantation is performed may be justified.

Riverine barriers and the geographic distribution of Amazonian species.

Rivers have been suggested to have played an important role in shaping present-day patterns of ecological and genetic variation among Amazonian species and communities. Recent molecular studies have provided mixed support for the hypothesis that large lowland Amazonian rivers have functioned as significant impediments to gene flow among populations of neotropical species. To date, no study has systematically evaluated the impact that riverine barriers might have on structuring whole Amazonian communities. Our analyses of the phylogeography of frogs and small mammals indicate that a putative riverine barrier (the Juruá River) does not relate to present-day patterns of community similarity and species richness. Rather, our results imply a significant impact of the Andean orogenic axis and associated thrust-and-fold lowland dynamics in shaping patterns of biotic diversity along the Juruá. Combined results of this and other studies significantly weaken the postulated role of rivers as major drivers of Amazonian diversification.

Hierarchical genetic structure and gene flow in three sympatric species of Amazonian rodents.

The population genetic structure of three species of Amazonian rodents (Oligoryzomys microtis, Oryzomys capito, and Mesomys hispidus) is examined for mtDNA sequence haplotypes of the cytochrome b gene by hierarchical analysis of variance and gene flow estimates based on fixation indices (NST) and coalescence methods. Species samples are from the same localities along 1000 km of the Rio Juruá in western Amazonian Brazil, but each species differs in important life history traits such as population size and reproductive rate. Average haplotype differentiation, hierarchical haplotype apportionment, and gene flow estimates are contrasted in discussing the current and past population structure. Two species exhibit isolation by distance patterns wherein gene flow is largely limited to geographically adjacent localities. Mesomys exhibits this pattern throughout its range along the river. More than 75% of haplotype variation is apportioned among localities and regions, and estimates of Nm for pair-wise comparisons are nearly always less than 1. Oligoryzomys shows weak isolation by distance, but only over the largest geographical distances. Nm values for this species are nearly always above 1 and most (about 80%) of haplotype variation is contained within local populations. In contrast, Oryzomys exhibits no genetic structure throughout its entire distribution; Nm values average 17 and nearly 90% of the total haplotype variance is contained within local populations. Although gene flow estimates are high, the pattern of Nm as a function of geographical distance suggests that this species experienced a more recent invasion of the region and is still in genetic disequilibrium under its current demographic conditions.

Reflex sympathetic dystrophy in children: an orthopedic perspective.

To design diagnostic criteria for reflex sympathetic dystrophy (RSD) and to initiate a prospective treatment protocol, we reviewed our experience with 49 episodes of RSD in 36 children. There were 24 females and 12 males; mean age at diagnosis was 13.4 years (range: 8 to 19); mean time from pain onset to correct diagnosis was 9.2 months (range: 1 to 53). Lower extremity involvement predominated. Pain was "severe" in 61%, and skin color changes, swelling, hyperesthesia, abnormal skin temperatures, muscle weakness, and decreased range of motion were all present in at least 75% of cases. Osteopenia was observed in 15 of 38 radiographs; of 24 bone scans, 7 were normal, 11 showed increased uptake, and 6 demonstrated decreased uptake. Of the 23 children who had psychological evaluations, 83% revealed some type of significant emotional dysfunction. Analgesic and antiinflammatory medications were not helpful, nor were local injections or regional blockades effective. An inpatient diagnostic and rehabilitation program for treating chronic pain, including orthopedics, rheumatology, psychology, and twice-daily physical therapy was most likely to lead to resumption of age-appropriate activities. Despite extensive physiological testing, physician, parent, and/or patient reluctance to accept absence of a primary organic disease was common. We present diagnostic criteria for pediatric RSD.

Microcomputer reconstruction for analysis of spinal deformity and lung volume in hypokyphotic scoliosis.

Current techniques for imaging chest deformity are limited to two-dimensional representations, and clinical testing for lung volume measurements are based on pulmonary function studies that are effort-dependent. The authors evaluated spine deformity and lung volume by using a new three-dimensional microcomputer imaging technique. Results from preoperative and postoperative chest computed tomograms underwent boundary detection by expert human observers. Data were then processed by polygon surface tiling to create three-dimensional color images of the spine and lungs for display. This computer technique allowed: 1) visualization of the anatomic relationships from any angle, 2) assessment of spinal deformity in relation to lung volume, and 3) measurement of individual lung volumes. Three-dimensional microcomputer imaging is a useful technique in objectively measuring lung volume and assessing postoperative changes.