34 research outputs found
Systematic review and meta-analysis of the diagnostic accuracy of ultrasonography for deep vein thrombosis
Background
Ultrasound (US) has largely replaced contrast venography as the definitive diagnostic test for deep vein thrombosis (DVT). We aimed to derive a definitive estimate of the diagnostic accuracy of US for clinically suspected DVT and identify study-level factors that might predict accuracy.
Methods
We undertook a systematic review, meta-analysis and meta-regression of diagnostic cohort studies that compared US to contrast venography in patients with suspected DVT. We searched Medline, EMBASE, CINAHL, Web of Science, Cochrane Database of Systematic Reviews, Cochrane Controlled Trials Register, Database of Reviews of Effectiveness, the ACP Journal Club, and citation lists (1966 to April 2004). Random effects meta-analysis was used to derive pooled estimates of sensitivity and specificity. Random effects meta-regression was used to identify study-level covariates that predicted diagnostic performance.
Results
We identified 100 cohorts comparing US to venography in patients with suspected DVT. Overall sensitivity for proximal DVT (95% confidence interval) was 94.2% (93.2 to 95.0), for distal DVT was 63.5% (59.8 to 67.0), and specificity was 93.8% (93.1 to 94.4). Duplex US had pooled sensitivity of 96.5% (95.1 to 97.6) for proximal DVT, 71.2% (64.6 to 77.2) for distal DVT and specificity of 94.0% (92.8 to 95.1). Triplex US had pooled sensitivity of 96.4% (94.4 to 97.1%) for proximal DVT, 75.2% (67.7 to 81.6) for distal DVT and specificity of 94.3% (92.5 to 95.8). Compression US alone had pooled sensitivity of 93.8 % (92.0 to 95.3%) for proximal DVT, 56.8% (49.0 to 66.4) for distal DVT and specificity of 97.8% (97.0 to 98.4). Sensitivity was higher in more recently published studies and in cohorts with higher prevalence of DVT and more proximal DVT, and was lower in cohorts that reported interpretation by a radiologist. Specificity was higher in cohorts that excluded patients with previous DVT. No studies were identified that compared repeat US to venography in all patients. Repeat US appears to have a positive yield of 1.3%, with 89% of these being confirmed by venography.
Conclusion
Combined colour-doppler US techniques have optimal sensitivity, while compression US has optimal specificity for DVT. However, all estimates are subject to substantial unexplained heterogeneity. The role of repeat scanning is very uncertain and based upon limited data
Aging-Aware Request Scheduling for Non-Volatile Main Memory
Modern computing systems are embracing non-volatile memory (NVM) to implement
high-capacity and low-cost main memory. Elevated operating voltages of NVM
accelerate the aging of CMOS transistors in the peripheral circuitry of each
memory bank. Aggressive device scaling increases power density and temperature,
which further accelerates aging, challenging the reliable operation of
NVM-based main memory. We propose HEBE, an architectural technique to mitigate
the circuit aging-related problems of NVM-based main memory. HEBE is built on
three contributions. First, we propose a new analytical model that can
dynamically track the aging in the peripheral circuitry of each memory bank
based on the bank's utilization. Second, we develop an intelligent memory
request scheduler that exploits this aging model at run time to de-stress the
peripheral circuitry of a memory bank only when its aging exceeds a critical
threshold. Third, we introduce an isolation transistor to decouple parts of a
peripheral circuit operating at different voltages, allowing the decoupled
logic blocks to undergo long-latency de-stress operations independently and off
the critical path of memory read and write accesses, improving performance. We
evaluate HEBE with workloads from the SPEC CPU2017 Benchmark suite. Our results
show that HEBE significantly improves both performance and lifetime of
NVM-based main memory.Comment: To appear in ASP-DAC 202
Atrasentan and renal events in patients with type 2 diabetes and chronic kidney disease (SONAR): a double-blind, randomised, placebo-controlled trial
Background: Short-term treatment for people with type 2 diabetes using a low dose of the selective endothelin A receptor antagonist atrasentan reduces albuminuria without causing significant sodium retention. We report the long-term effects of treatment with atrasentan on major renal outcomes. Methods: We did this double-blind, randomised, placebo-controlled trial at 689 sites in 41 countries. We enrolled adults aged 18–85 years with type 2 diabetes, estimated glomerular filtration rate (eGFR)25–75 mL/min per 1·73 m 2 of body surface area, and a urine albumin-to-creatinine ratio (UACR)of 300–5000 mg/g who had received maximum labelled or tolerated renin–angiotensin system inhibition for at least 4 weeks. Participants were given atrasentan 0·75 mg orally daily during an enrichment period before random group assignment. Those with a UACR decrease of at least 30% with no substantial fluid retention during the enrichment period (responders)were included in the double-blind treatment period. Responders were randomly assigned to receive either atrasentan 0·75 mg orally daily or placebo. All patients and investigators were masked to treatment assignment. The primary endpoint was a composite of doubling of serum creatinine (sustained for ≥30 days)or end-stage kidney disease (eGFR <15 mL/min per 1·73 m 2 sustained for ≥90 days, chronic dialysis for ≥90 days, kidney transplantation, or death from kidney failure)in the intention-to-treat population of all responders. Safety was assessed in all patients who received at least one dose of their assigned study treatment. The study is registered with ClinicalTrials.gov, number NCT01858532. Findings: Between May 17, 2013, and July 13, 2017, 11 087 patients were screened; 5117 entered the enrichment period, and 4711 completed the enrichment period. Of these, 2648 patients were responders and were randomly assigned to the atrasentan group (n=1325)or placebo group (n=1323). Median follow-up was 2·2 years (IQR 1·4–2·9). 79 (6·0%)of 1325 patients in the atrasentan group and 105 (7·9%)of 1323 in the placebo group had a primary composite renal endpoint event (hazard ratio [HR]0·65 [95% CI 0·49–0·88]; p=0·0047). Fluid retention and anaemia adverse events, which have been previously attributed to endothelin receptor antagonists, were more frequent in the atrasentan group than in the placebo group. Hospital admission for heart failure occurred in 47 (3·5%)of 1325 patients in the atrasentan group and 34 (2·6%)of 1323 patients in the placebo group (HR 1·33 [95% CI 0·85–2·07]; p=0·208). 58 (4·4%)patients in the atrasentan group and 52 (3·9%)in the placebo group died (HR 1·09 [95% CI 0·75–1·59]; p=0·65). Interpretation: Atrasentan reduced the risk of renal events in patients with diabetes and chronic kidney disease who were selected to optimise efficacy and safety. These data support a potential role for selective endothelin receptor antagonists in protecting renal function in patients with type 2 diabetes at high risk of developing end-stage kidney disease. Funding: AbbVie
Acoustic studies of ternary mixture phenanthrene – toluene – heptane as a model of natural flocculating system
Complexity of natural systems causes that results of
experimental studies are often ambiguous and extremely unrewarding in
interpretation. To overcome this difficulty, relative simple model systems
may be investigated in order to provide physical grounds for further
discussion. This study deals with adiabatic compressibility of liquid
ternary system consisting of phenanthrene, toluene and heptane. Increase of
heptane concentration in the mixture changes considerably the partial
compressibility of phenanthrene, from common positive value in pure toluene
up to clearly negative ones. This is most probably because of
self-association of phenanthrene due to strong London forces. Heptane seems
to promote the self-association. These feature of the investigated system
suggests its usefulness in studies of flocculation of asphaltenes from crude
oils
Ultrasonic studies of relaxation phenomena in crude oils and their solutions
Asphaltenes are operationally defined as non-volatile and
polar components of crude oils soluble in toluene and insoluble in
-heptane. They gradually plug production wells and pipes because of
flocculation and precipitation causing technical problems and financial
losses. The flocculation is reversible. Absorption of ultrasound have been
measured in three crude oils and their mixtures with toluene at frequencies
from 2.4 to 80 MHz at K. Processes with relaxation times in the
interval from 10 to 100 ns were found in the crude oils. The relaxation may
be due to aggregation of asphaltenes, that in favourable conditions may lead
to flocculation. Relaxation processes in the solutions are faster, with
relaxation times partly outside the measurement range. Most probably, the
molecules of asphaltenes easier translate and rotate in the solutions than
in viscous crude oils. If the proposed model is correct, one may expect
relaxation times shorter in deasphaltenated oils. On the other hand, the
relaxation may be ascribed to bending long hydrocarbon chains. That process
is also rather slow
Effect of dilution on compressibility of naproxen in acetonitrile studied by ultrasonic method
Naproxen, ibuprofen, and ketoprofen are non-steroidal
anti-inflammatory drugs. All of them belong to chiral
2-arylpropionic acids (2-APAs). Chiral compounds may remain in a
patient's body as two antimers, even if administered as a single
one, due to transenantiomerization. That is dangerous if therapeutic
enantiomer has a toxic antipode. Chromatographic data suggest that
solutions of -(+)-naproxen in acetonitrile are stiffer than the
pure solvent that favours oscillatory transenantiomerisation.
Acoustic and volumetric studies of dilute solutions of naproxen in
acetonitrile have been undertaken to verify that supposition. The
molar adiabatic compressibility and volume depend linearly on the
molar percent of naproxen at temperatures from 298.15 K to
313.15 K. Limiting partial compressibility of naproxen is close to
zero and decreases slightly with increasing temperature. Thus, the
compressibility of dilute solutions is mainly due to compressibility
of acetonitrile, while naproxen is virtually incompressible. The
hydrogen-bonded dimers of naproxen probably remain intact, even at
infinite dilution
Behavioral Health and Adult Milestones in Young Adults With Perinatal HIV Infection or Exposure
BACKGROUND: Young adults living with perinatally acquired HIV infection (PHIVYAs) are at risk for poor biomedical and behavioral health outcomes. Few studies offer a comprehensive overview of the functioning of this population in young adulthood and the role of HIV. METHODS: Data come from the Child and Adolescent Self-Awareness and Health Study, a longitudinal behavioral health cohort study of PHIVYAs and perinatally HIV-exposed but uninfected young adults (PHEUYAs) who are compared on psychiatric and neurocognitive functioning, sexual and substance use behaviors, health and reproductive outcomes, and young adult milestones. RESULTS: Overall, 27% of participants met criteria for a psychiatric disorder, including mood (11%), anxiety (22%), and substance use (28%), with no HIV status differences. PHIVYAs performed worse on 2 neurocognitive tests. There were no HIV status differences in condomless sex (41%) or pregnancies (41% women; 38% men). Both groups exhibited similar adult milestones: 67% graduated high school or an equivalent, 19% were in college, and 42% were employed. However, 38% were neither in school or working, 12% reported incarceration, and 16% were ever homeless. Among PHIVYAs, 36% were viremic (\u3e200 copies per mL), and 15% were severely immunocompromised (CD4(+) cell count \u3c100 cells per mm(3)). CONCLUSIONS: Many PHIVYAs achieve adult milestones related to school, employment, sexual relationships, and starting families. However, they and PHEUYAs have high rates of psychiatric and substance use disorders and behavioral risks, which can jeopardize long-term health and adult functioning, particularly in the context of HIV. These findings underscore an urgent need to escalate interventions