Multiband compression limiting for hearing-impaired listeners

Four multiband compression limiters and two linear amplification systems were compared in terms of the intelligibility of consonant-vowel-consonant (CVC) nonsense syllables for two hearing-impaired listeners over a 30 dB range of input levels. Each system incorporated one of two frequency-gain characteristics and one of three limiting characteristics (no limiting, moderate limiting, or severe limiting). The subjects were instructed to choose overall listening levels that would permit speech spanning the range of input levels to be as intelligible as possible and comfortable for long-term listening. Relative to linear amplification, the overall gain selected by the subjects increased by roughly 5 and 11 dB for the moderate and severe limiter, respectively. With linear amplification, the maximum score, 82 percent correct, was obtained at the highest input level and scores fell roughly 34 percentage points as input level was reduced. With compression limiting, although the maximum scores, 81 percent and 79 percent correct, were obtained at lower input levels, performance was comparable to that with linear amplification. Also, scores spanned a range of only 22 and 9 percentage points across the range of input levels with the moderate and severe limiter, respectively. This benefit was due to the improved scores provided by compression limiting at the low input levels. However, this advantage was offset somewhat by the disadvantage provided by compression at high input levels relative to linear amplification. Error analysis indicated that the spectral degradations introduced by independent compression of 16 frequency bands may have caused the reduced intelligibility at higher input levels.     

Removal of the endothelial layer in perfused mesenteric vascular bed of the rat.

The endothelial layer was removed from the isolated mesenteric vascular bed of the rat by perfusion with hypotonic Tyrode solution for 12.5 min. This procedure damaged more than 95% of the endothelial cells. After endothelial removal, the response to norepinephrine was significantly enhanced, whereas the relaxation induced by acetylcholine (ACh) was completely abolished. The results of this work show that perfusion with hypotonic solutions provides a reliable method of endothelial removal in isolated perfused vascular beds, allowing the study of endothelial-dependent vascular responses.     

Changes in humoral immune response after SARS-CoV-2 infection in liver transplant recipients compared to immunocompetent patients

The protective capacity and duration of humoral immunity after SARS-CoV-2 infection are not yet understood in solid organ transplant recipients. A prospective multicenter study was performed to evaluate the persistence of anti-nucleocapsid IgG antibodies in liver transplant recipients 6 months after coronavirus disease 2019 (COVID-19) resolution. A total of 71 liver transplant recipients were matched with 71 immunocompetent controls by a propensity score including variables with a well-known prognostic impact in COVID-19. Paired case–control serological data were also available in 62 liver transplant patients and 62 controls at month 3 after COVID-19. Liver transplant recipients showed a lower incidence of anti-nucleocapsid IgG antibodies at 3 months (77.4% vs. 100%, p < .001) and at 6 months (63.4% vs. 90.1%, p < .001). Lower levels of antibodies were also observed in liver transplant patients at 3 (p = .001) and 6 months (p < .001) after COVID-19. In transplant patients, female gender (OR = 13.49, 95% CI: 2.17–83.8), a longer interval since transplantation (OR = 1.19, 95% CI: 1.03–1.36), and therapy with renin–angiotensin–aldosterone system inhibitors (OR = 7.11, 95% CI: 1.47–34.50) were independently associated with persistence of antibodies beyond 6 months after COVID-19. Therefore, as compared with immunocompetent patients, liver transplant recipients show a lower prevalence of anti-SARS-CoV-2 antibodies and more pronounced antibody levels decline.     

Stroke as the first manifestation of calcific aortic stenosis

Heart valve calcifications are rarely recognized as a potential source for cerebral embolism. Previous studies have identified mitral, but not aortic, valve calcifications to be risk factors for stroke. Based on these studies, heart surgery is unlikely to be indicated in patients who present with a stroke and an 'incidental' aortic valve calcification. We report a case of a 46-year-old man presenting with acute onset of left-sided weakness and numbness. A previous smoking history was the only cardiovascular risk factor found. Head CT scan revealed a right middle cerebral artery territory infarct and an adjacent high-density lesion. CT angiography demonstrated the presence of calcific embolic material in the middle cerebral artery. A search for embolic sources revealed a calcific aortic stenosis (CAS). Initially placed on coumadin, the patient developed silent myocardial infarction 2 months later, presumed to be also embolic in origin from the CAS. After aortic valve replacement, the patient has been symptom-free during a 2-year follow-up. In conclusion, CT angiography may be the method of choice for detecting calcific cerebral emboli, and demonstration of a causal relationship between CAS and an embolic stroke by CT angiography may be an important adjunct in surgical decision-making.     

Comparison of 2 proposed MLVA protocols for subtyping non-O157:H7 verotoxigenic Escherichia coli

Multiple locus variable number tandem repeats (VNTRs) analysis (MLVA) has become a reliable tool, able to establish genetic relationships for epidemiological surveillance and molecular subtyping of pathogens such as verotoxigenic Escherichia coli (VTEC). This emerging pathogen whose primary reservoir is the cattle causes severe disease in humans, such as hemorrhagic colitis and hemolytic uremic syndrome. With the aim of comparing a recently proposed MLVA assay with that used routinely in our laboratory, we analyzed a set of VTEC isolates (n = 72) obtained from meat using both assays. All samples could be typed by the new MLVA assay, and an increase in the number of distinct profiles (31–43) was observed. However, intraserotype resolution was not significantly enhanced; thus, the incorporation of more VNTR loci is still needed to achieve a greater discrimination among non-O157:H7 serotypes.     

A full-length recombinant Plasmodium falciparum PfRH5 protein induces inhibitory antibodies that are effective across common PfRH5 genetic variants

The lack of an effective licensed vaccine remains one of the most significant gaps in the portfolio of tools being developed to eliminate Plasmodium falciparum malaria. Vaccines targeting erythrocyte invasion – an essential step for both parasite development and malaria pathogenesis – have faced the particular challenge of genetic diversity. Immunity-driven balancing selection pressure on parasite invasion proteins often results in the presence of multiple, antigenically distinct, variants within a population, leading to variant-specific immune responses. Such variation makes it difficult to design a vaccine that covers the full range of diversity, and could potentially facilitate the evolution of vaccine-resistant parasite strains. In this study, we investigate the effect of genetic diversity on invasion inhibition by antibodies to a high priority P. falciparum invasion candidate antigen, P. falciparum Reticulocyte Binding Protein Homologue 5 (PfRH5). Previous work has shown that virally delivered PfRH5 can induce antibodies that protect against a wide range of genetic variants. Here, we show that a full-length recombinant PfRH5 protein expressed in mammalian cells is biochemically active, as judged by saturable binding to its receptor, basigin, and is able to induce antibodies that strongly inhibit P. falciparum growth and invasion. Whole genome sequencing of 290 clinical P. falciparum isolates from across the world identifies only five non-synonymous PfRH5 SNPs that are present at frequencies of 10% or more in at least one geographical region. Antibodies raised against the 3D7 variant of PfRH5 were able to inhibit nine different P. falciparum strains, which between them included all of the five most common PfRH5 SNPs in this dataset, with no evidence for strain-specific immunity. We conclude that protein-based PfRH5 vaccines are an urgent priority for human efficacy trials.     

Peutz-Jeghers syndrome

Peutz-Jeghers syndrome is an autonomic dominant disease characterized by hamartomatous polyps and mucocutaneous hyperpigmentation. We present 16 cases; females were more affected. The most common presenting complaints were of gastrointestinal tract. All polyps found were hamartomatous with general distribution through gastrointestinal tract. Endoscopic polypectomy should be carried out for treatment. Radiologic, endoscopic and histologic studies should be conducted for long-term follow-up, because of high risk of malignancy.