Effects of Sustained Low-Level Elevations of Carbon Dioxide on Cerebral Blood Flow and Autoregulation of the Intracerebral Arteries in Humans

Cerebral blood flow velocity (CBFv) was measured by insonating the middle cerebral arteries of 4 subjects using a 2 Mhz transcranial Doppler. Ambient CO2 was elevated to 0.7% for 23 days in the first study and to 1.2% for 23 days in the same subjects in the second study. By non-parametric testing CBFv was elevated significantly by +35% above pre-exposure levels during the first 1-3 days at both exposure levels after which CBFv progressively readjusted to pre-exposure levels. Despite similar CBFv responses, headache was only reported during the initial phase of exposure to 1.2% CO2. Vascular reactivity to CO2 assessed by rebreathing showed a similar pattern with the CBFv increases early in the exposures being greater than those elicited later. An increase in metabolic rate of the visual cortex was evoked by having the subjects open and close their eyes during a visual stimulus. Evoked CBFv responses measured in the posterior cerebral artery were also elevated in the first 1-3 days of both studies returning to pre-exposure levels as hypercapnia continued. Cerebral vascular autoregulation assessed by raising head pressure during 10 deg head-down tilt both during the low-level exposures and during rebreathing was unaltered. There were no changes in the retinal microcirculation during serial fundoscopy studies. The time-dependent changes in CO2 vascular reactivity might be due either to retention of bicarbonate in brain extracellular fluid or to progressive increases in ventilation, or both. Cerebral vascular autoregulation appears preserved during chronic exposure to these levels of ambient CO2

Air pollution and the microvasculature: A cross-sectional assessment of in vivo retinal images in the population-based multi-ethnic study of atherosclerosis (MESA)

10.1371/journal.pmed.1000372PLoS Medicine711

Insight on genes affecting tuber development in potato upon <i>Potato spindle tuber viroid</i> (PSTVd) infection

Potato (Solanum tuberosum L) is a natural host of Potato spindle tuber viroid (PSTVd) which can cause characteristic symptoms on developing plants including stunting phenotype and distortion of leaves and tubers. PSTVd is the type species of the family Pospiviroidae, and can replicate in the nucleus and move systemically throughout the plant. It is not well understood how the viroid can affect host genes for successful invasion and which genes show altered expression levels upon infection. Our primary focus in this study is the identification of genes which can affect tuber formation since viroid infection can strongly influence tuber development and especially tuber shape. In this study, we used a large-scale method to identify differentially expressed genes in potato. We have identified defence, stress and sugar metabolism related genes having altered expression levels upon infection. Additionally, hormone pathway related genes showed significant up- or down-regulation. DWARF1/DIMINUTO, Gibberellin 7-oxidase and BEL5 transcripts were identified and validated showing differential expression in viroid infected tissues. Our study suggests that gibberellin and brassinosteroid pathways have a possible role in tuber development upon PSTVd infection

Carotid artery plaque composition : Relationship to clinical presentation and ultrasound B-mode imaging

Objective: To correlate B-mode ultrasound findings to carotid plaque histology. Design: European multicentre study (nine centres). Material and Methods: Clinical presentation and risk factors were recorded and preoperative ultrasound Duplex scanning with special emphasis on B-mode imaging studies was performed in 270 patients undergoing carotid endarterectomy. Perioperatively macroscopic plaque features were evaluated and the removed specimens were analysed histologically for fibrous tissue, calcification and 'soft tissue' (primarily haemorrhage and lipid). Results: Males had more soft tissue than females (p = 0.0006), hypertensive patients less soft tissue than normotensive (p = 0.01) and patients with recent symptoms more soft tissue than patients with earlier symptoms (p = 0.004). There was no correlation between surface description on ultrasound images compared to the surface judged intraoperatively by the surgeon. Echogenicity on B-mode images was inversely related to soft tissue (p=0.005) and calcification ions directly related to echogenicity (p < 0.0001). Heterogeneous plaques contained more calcification than homogeneous (p = 0.003), however there was no difference in content of soft tissue. Conclusion: Ultrasound B-mode characteristics are related to the histological composition of carotid artery plaques and to patient's history. These results may imply that patients with distant symptoms may be regarded and treated as asymptomatic patients whereas asymptomatic patients with echolucent plaques should be considered for carotid endarterectomy

Decision Initiation, Decision Implementation, and the Allocation of Decision Rights

Organizations must not only take the right decisions, they must also ensure that these decisions are effectively implemented. Fama & Jensen (1983) argue that the same members of many organization are often responsible for both decision initiation and implementation. If these have social preferences, they might thus sabotage both project choices and implementation to express their discontent with the allocation of decision rights. How decisions come about also affects implementation if workers have reciprocal fairness concerns. Our experimental evidence demonstrates that the possibility to sabotage implementation leads to more delegation, but only if workers have high costs of obstructing informed decisions. We further find that the allocation of authority as such affects implementation

Incidence of neurological complications in patients with native-valve infective endocarditis and cerebral microembolism: an open cohort study

The objective of this open cohort study was to assess the association between neurological complications in patients with definite native-valve infective endocarditis (IE) and cerebral microembolism (MES). MES detection was performed with 1-h, bilateral middle cerebral arteries (MCA) insonation using a transcranial Doppler ultrasound (TCD) machine. Thirty patients with definite native-valve IE were stratified into 2 groups based upon the presence of MES. The most striking difference between the 2 groups of patients was the incidence of clinically evident neurological complications. Neurological complications of IE occurred in 10 (83.3%) patients with positive MES and in 6 (33.3%) MES-negative patients (p=0.021). Ischaemic stroke was the most common complication, occurring in 11 of 16 patients, followed by meningitis in 4 patients and cerebritis in 1 patient. There was a trend towards greater in-hospital mortality in patients with recorded MES than in the MES-negative, although this was not statistically significant (33.3% vs 16.6%; p=0.392). Our results reveal a significant association between MES and neurological complications in patients with native-valve IE. TCD is a promising tool in predicting individual patient risk for neurological complications of IE