Fine-scale species distribution modelling and genotyping by sequencing to examine hybridisation between two narrow endemic plant species.

Hybridization has an important and often positive role in plant evolution. However, it can also have negative consequences for species. Two closely related species of Ornduffia are endemic to the Porongurup Range in the South West Australian Global Biodiversity Hotspot. The rare Ornduffia calthifolia is found exclusively on the summits, while O. marchantii is more widely dispersed across a greater range of elevation and is not considered threatened. Hybridisation in suitable overlapping habitat has been suspected between them for decades. Here we combine genotyping by sequencing to verify hybridisation genetically, and fine scale (2 m resolution) species distribution modelling (SDM) to test if hybrids occur in suitable intersecting habitat. From a study area of c. 4700 ha, SDM identified c. 275 ha and c. 322 ha of suitable habitat for O. calthifolia and O. marchantii, respectively. We identified range overlap between species of c. 59 ha), which enveloped 32 individuals confirmed to be hybrids. While the hybrids were at the margin of suitable habitat for O. marchantii, their preference for elevated habitat was closer to the more narrowly distributed O. calthifolia. The combination of genetic data and fine scale spatial modelling approaches enabled a better understanding of hybridisation among taxa of conservation significance. However, the level to which hybrid proliferation and competition for habitat presents as a threat to O. calthifolia is currently unknown and requires priority in conservation management given the threats from global warming and disturbance by tourism.

Extracorporeal membrane oxygenation for early graft dysfunction in lung transplantation: a case report.

Although extracorporeal membrane oxygenation (ECMO) has become standard treatment for neonatal respiratory failure, the results of ECMO in adults have been less encouraging. With technical improvements in membrane oxygenators and revised ECMO protocols, there has been renewed interest in ECMO for adults with severe acute respiratory failure. However, few cases of ECMO as an adjunct to adult lung transplantation have been reported. We present the case of a 20-year-old woman with cystic fibrosis who underwent bilateral single lung transplantation. She had development of severe graft dysfunction in the immediate postoperative period requiring support with ECMO for stabilization.

Bio-Medicus centrifugal ventricular support for postcardiotomy cardiac failure: a review of 129 cases.

BACKGROUND: Bio-Medicus centrifugal ventricular support has been used widely for postcardiotomy cardiac failure. The purpose of this study was to review a large series of support patients examining complications and outcomes. METHODS: One hundred twenty-nine patients undergoing cardiac operations at The Methodist Hospital in Houston, Texas, were placed on Bio-Medicus centrifugal ventricular support for postcardiotomy cardiac failure; 102 were male and 27 were female with a mean age of 61.6 years. These patients were selected for ventricular support based solely on failure to be weaned from cardiopulmonary bypass or progressive postcardiotomy cardiac failure shortly after arrival in the intensive care unit. RESULTS: These patients experienced numerous complications including coagulopathy, renal insufficiency or failure, sepsis, neurologic deficits, ventricular failure, arrhythmias, and death; 56.3% of patients were weaned from mechanical support and 21.0% were discharged alive. Causes of death included ventricular failure (62.4%), arrhythmias (12.9%), triage (6.9%), perioperative myocardial infarction or cardiac arrest (5.0%), coagulopathy (4.0%), sepsis syndrome (4.0%), cardiac graft failure (3.0%), and device related (1.0%). The one device-related death was a venous cannula dislodgment in the intensive care unit with subsequent exsanguination. Device-related complications were seen in only 1.6% of patients. CONCLUSIONS: Bio-Medicus centrifugal ventricular support can be implemented rapidly and relatively easily. There are few device-related complications and the cost is relatively inexpensive compared with other assist systems. This series demonstrates that a substantial number of patients who experience reversible postcardiotomy myocardial injury will benefit from temporary centrifugal ventricular support.

Clinical experience with BioMedicus centrifugal ventricular support in 172 patients.

One hundred and seventy-two patients at The Methodist Hospital in Houston, Texas, were placed on BioMedicus centrifugal ventricular support. One hundred thirty-nine patients were male and 33 were female with a mean age of 59.7 years. Reasons for support were postcardiotomy cardiac failure (129 patients), cardiac allograft failure (17 patients), bridge to transplantation (10 patients), resuscitation (7 patients), postpercutaneous transluminal coronary angioplasty emergent (2 patients), and other (7 patients). Support was by left ventricular assist device in 108 patients, right ventricular assist device in 20 patients, and biventricular assist device in 44 patients. Eighty-four patients (48.8%) were weaned from the ventricular assist device, and 88 patients (51.2%) were not weaned. Thirty-four patients (20.0%) were discharged from the hospital. Complications included coagulopathy, renal insufficiency/failure, respiratory insufficiency/failure, neurological deficits, sepsis, arrhythmias, and device-related complications. Overall causes of death were ventricular failure (55.1%), triage (13.0%), arrhythmias (9.4%), graft failure (5.9%), coagulopathy (4.3%), sepsis syndrome (2.9%), device-related (0.7%), and other (0.7%). BioMedicus centrifugal ventricular support can be implemented rapidly and easily. Device-related complications are few (1.2%), and it is relatively inexpensive when compared with other ventricular assist systems. This series demonstrates that a substantial number of patients may benefit from temporary centrifugal ventricular support.

The geochemical behavior of aluminum in acidified surface waters.

Speciation calculations for aluminum, in water samples taken from a drainage basin containing acid mine waters, demonstrate a distinct transition from conservative behavior for pH below 4.6 to nonconservative behavior for pH above 4.9. This transition corresponds to the pK for the first hydrolysis constant of the aqueous aluminum ion and appears to be a consistent phenomenon independent of field location, ionic strength, and sulfate concentration. Nonconservative behavior is closely correlated with the equilibrium solubility of a microcrystalline gibbsite or amorphous aluminum hydroxide.