Discover the most talked about and latest scientific content & concepts.

Concept: Leak


Purpose To investigate whether the blood-brain barrier (BBB) leaks blood-circulating substances in patients with early forms of Alzheimer disease (AD), and if so, to examine the extent and pattern of leakage. Materials and Methods This study was approved by the local medical ethical committees of the Maastricht University Medical Center and Leiden University Medical Center, and written informed consent was obtained from all subjects. For this pilot study, 16 patients with early AD and 17 healthy age-matched control subjects underwent dynamic contrast material-enhanced magnetic resonance (MR) imaging sequence with dual time resolution for 25 minutes. The Patlak graphical approach was used to quantify the BBB leakage rate and local blood plasma volume. Subsequent histogram analysis was used to determine the volume fraction of the leaking brain tissue. Differences were assessed with linear regression analysis, adjusted for confounding variables. Results The BBB leakage rate was significantly higher in patients compared with that in control subjects in the total gray matter (P < .05) and cortex (P = .03). Patients had a significantly higher volume fraction of the leaking brain tissue in the gray matter (P = .004), normal-appearing white matter (P < .04), deep gray matter (P = .01), and cortex (P = .004). When all subjects were considered, scores on the Mini-Mental State Examination decreased significantly with increasing leakage in the deep gray matter (P = .007) and cortex (P < .05). Conclusion The results of this study showed global BBB leakage in patients with early AD that is associated with cognitive decline. A compromised BBB may be part of a cascade of pathologic events that eventually lead to cognitive decline and dementia. (©)RSNA, 2016 Online supplemental material is available for this article.

Concepts: Regression analysis, Linear regression, Neuron, Brain, Informed consent, Thermodynamics, Cerebellum, Leak


ABSTRACT Respiratory protection provided by a particulate respirator is a function of particle penetration through filter media and through faceseal leakage. Faceseal leakage largely contributes to the penetration of particles through respirator and compromises protection. When faceseal leaks arise, filter penetration is assumed to be negligible. The contribution of filter penetration and faceseal leakage to total inward leakage (TIL) of submicron size bioaerosols is not well studied. To address this issue, TIL values for two N95 filtering facepiece respirator (FFR) models and two surgical mask (SM) models sealed to a manikin were measured at 8 L and 40 L breathing minute volumes with different artificial leak sizes. TIL values for different size (20-800 nm, electrical mobility diameter) NaCl particles representing submicron size bioaerosols were measured using a scanning mobility particle sizer. Efficiency of filtering devices was assessed by measuring the penetration against NaCl aerosol similar to the method used for NIOSH particulate filter certification. Results showed that the most penetrating particle size (MPPS) was ∼45 nm for both N95 FFR models and one of the two SM models, and ∼350 nm for the other SM model at sealed condition with no leaks as well as with different leak sizes. TIL values increased with increasing leak sizes and breathing minute volumes. Relatively, higher efficiency N95 and SM models showed lower TIL values. Filter efficiency of FFRs and SMs influenced the TIL at different flow rates and leak sizes. Overall, the data indicate that good fitting higher efficiency FFRs may offer higher protection against submicron size bioaerosols.

Concepts: Sociology, Aerosol, Respirator, Filters, Leak, Masks, Bioaerosol, Surgical mask


A 61-year-old man with severe chronic obstructive pulmonary disease presented to our hospital with recurrence of a right-sided spontaneous secondary pneumothorax. Thoracoscopic abrasion of the parietal pleura was performed, but an important air leak persisted. Presumed to originate from a bulla in the right upper lobe, bullectomy and pleural decortication were performed, but leakage remained. Lobectomy was considered, and quantitative ventilation/perfusion SPECT was performed to predict the functional outcome.Fused high-resolution CT/Tc Technegas images localized leakage not only to a bleb in the right upper lobe but also to the subcutaneous emphysema in the thoracic wall. The air leak resolved after conservative treatment.

Concepts: Pulmonology, Lung, Emphysema, Pneumothorax, Thoracic cavity, Pleural cavity, Tension pneumothorax, Leak


Anastomotic dehisense is a serious complication of anterior resections. We have had success in our centre utilising Endosponge therapy to salvage anastomotic leaks but this requires multiple endoscopic sessions and can take around 6 weeks to heal in some cases. This can delay further management such as chemotherapy.

Concepts: Resection, Endoscopic retrograde cholangiopancreatography, Endoscopy, Leak


Anastomotic leakage is a feared complication following colorectal surgery. Early prediction results in improved clinical outcome, but accurate predictive factors remain elusive. Many biomarkers have been studied with respect to diagnosis of anastomotic leakage but the concept of trajectory testing, using biomarkers, has not been assessed with regards to early diagnosis of anastomotic leak.

Concepts: Prediction, Leak


Future energy systems may rely on natural gas as a low-cost fuel to support variable renewable power. However, leaking natural gas causes climate damage because methane (CH4) has a high global warming potential. In this study, we use extreme-value theory to explore the distribution of natural gas leak sizes. By analyzing ~15,000 measurements from 18 prior studies, we show that all available natural gas leakage datasets are statistically heavy-tailed, and that gas leaks are more extremely distributed than other natural and social phenomena. A unifying result is that the largest 5% of leaks typically contribute over 50% of the total leakage volume. While prior studies used lognormal model distributions, we show that lognormal functions poorly represent tail behavior. Our results suggest that published uncertainty ranges of CH4 emissions are too narrow, and that larger sample sizes are required in future studies to achieve targeted confidence intervals. Additionally, we find that cross-study aggregation of datasets to increase sample size is not recommended due to apparent deviation between sampled populations. Understanding the nature of leak distributions can improve emission estimates, better illustrate their uncertainty, allow prioritization of source categories, and improve sampling design. Also, these data can be used for more effective design of leak detection technologies.

Concepts: Carbon dioxide, Sample size, Natural gas, Methane, Greenhouse gas, Global warming, Leak, Gas leak


Spontaneous pneumothorax is a common pathology. International guidelines suggest pleurodesis for non-resolving air leak or recurrence prevention at second occurrence. This study comprehensively reviews the existing literature regarding chemical pleurodesis efficacy.

Concepts: Review, Pneumothorax, Leak


Fugitive emissions from natural gas systems are the largest anthropogenic source of the greenhouse gas methane (CH4) in the U.S. and contribute to the risk of explosions in urban environments. Here, we report on a survey of CH4 emissions from 100 natural gas leaks in cast iron distribution mains in Metro Boston, MA. Direct measures of CH4 flux from individual leaks ranged from 4.0 - 2.3 × 10(4) g CH4•day(-1). The distribution of leak size is positively skewed, with 7% of leaks contributing 50% of total CH4 emissions measured. We identify parallels in the skewed distribution of leak size found in downstream systems with midstream and upstream stages of the gas process chain. Fixing ‘superemitter’ leaks will disproportionately stem greenhouse gas emissions. Fifteen percent of leaks surveyed qualified as potentially explosive (Grade 1), and we found no difference in CH4 flux between Grade 1 leaks and all remaining leaks surveyed (p = 0.24). All leaks must be addressed, as even small leaks cannot be disregarded as ‘safely leaking.’ Key methodological impediments to quantifying and addressing the impacts of leaking natural gas distribution infrastructure involve inconsistencies in the manner in which gas leaks are defined, detected, and classified. To address this need, we propose a two-part leak classification system that reflects both the safety and climatic impacts of natural gas leaks.

Concepts: Carbon dioxide, Climate change, Natural gas, Methane, Coal, Greenhouse gas, Leak, Gas leak


Anastomotic leaks represent one of the most alarming complications following any gastrointestinal anastomosis due to the substantial effects on post-operative morbidity and mortality of the patient with long-lasting effects on the functional and oncologic outcomes. There is a lack of consensus related to the definition of an anastomotic leak, with a variety of options for prevention and management. A number of patient-related and technical risk factors have been found to be associated with the development of an anastomotic leak and have inspired the development of various preventative measures and technologies. The International Multispecialty Anastomotic Leak Global Improvement Exchange group was convened to establish a consensus on the definition of an anastomotic leak as well as to discuss the various diagnostic, preventative, and management measures currently available.

Concepts: Digestive system, Natural gas, Leak


In 1960, Dr. Bayard Clarkson described a woman experiencing sporadic, recurrent episodes of shock and anasarca. Plasma from an acute attack induced a “shock”-like syndrome when injected into rats. The enigmatic “Systemic Capillary Leak Syndrome” (SCLS) named for Dr. Clarkson is characterized by transient and severe, but reversible, hemoconcentration and hypoalbuminemia due to leakage of fluids and macromolecules into tissues. Although < 500 cases of SCLS have been reported in the literature since 1960, the condition is probably under-diagnosed due to lack of awareness and a high mortality without treatment. Allergists should be vigilant of this diagnosis since its presentation can resemble more common plasma leakage syndromes including angioedema or systemic anaphylaxis. Although the precise molecular etiology of SCLS remains unknown, substantial advances over the last five years have increased our understanding of SCLS pathogenesis.

Concepts: Pathology, The Canon of Medicine, Shock, Syndromes, Woman, Anaphylaxis, Leak, Syndrome