Two-state compression of spectral tilt: individual differences and psychoacoustical limitations to the benefit from compression

A psychoacoustic rationale was developed for a hearing aid design in which compression of spectral tilt was incorporated without any instantaneous nonlinear distortion. This involved switching between a 'flat' and a 'rising' frequency response; the switching was done slowly to avoid audible transients and was controlled by feedback derived from comparison of output levels in low- and high-frequency channels, approximating voiced/unvoiced detection. The effect of this switching process was to narrow the distribution of spectral tilt values compared with the input. Asynchrony between the switching and the triggering speech structures was avoided by also delaying the signal path. Unfortunately, hearing-impaired listeners performed more poorly on the switching system than on either of the control 'flat' or 'rising' frequency-responses. An explanation is offered (on the basis of growing evidence from perceptual experiments) of the perceptual importance of temporal envelope contours within individual frequency bands. It was possible, in part, to predict individuals' results in the switching condition from age and audiometric or psychoacoustic characteristics. The results suggest a modification to the switching design, and they point to an intrinsic limit to the ability of all hearing aids of the compression type to enhance intelligibility.     

The collagen-like component of the complement system, C1q, is recognized by 7 S autoantibodies and is functionally impaired in synovial fluids of patients with rheumatoid arthritis.

Cross-reactivity between type II collagen (CII) and C1q, the collagen-like subunit of the first component of complement, has been demonstrated in synovial fluid (SF) from rheumatoid arthritis (RA) patients. Many authors have studied autoimmunity to CII in RA, but little work has been done on autoimmunity to C1q in RA. In the data presented here, we have been able to show that in addition to native C1q, an altered form of C1q is present in SF from RA patients. Furthermore, a low molecular weight form of C1q is present in RA SF, although its role, if any, in the pathogenesis of RA is unclear. The presence in these RA SF of C1q-specific antibodies (IgG and IgM) has been studied and we have partially characterized the antibody moieties involved. As well as binding to C1q and fragments representing the collagen-tails from C1q, 7 S IgG autoantibodies against C1q also bind to a C1q molecule altered in vitro by incubation with reactive oxygen species and to the non-apeptide KGEQGEPGA (representing residues 26-34 from the C1q A-chain), which has previously been shown to suppress the onset of CII-induced arthritis in an animal model.     

Perinatal distress,an appraisal perspective

Objective: The aim of this study was to identify the particular appraisals that shape maternal distress using the theoretical framework of Appraisal Theory of Emotions, which suggests that experienced emotions are triggered by the appraisal of specific situations. Background: Perinatal distress has been extensively studied. Symptoms range from mild to clinically significant. While major risk factors have been elucidated, cognitive components that may trigger distress need further clarification. Method: 122 women recruited during their third trimester of pregnancy completed measures of distress and appraisal during late pregnancy, within 7–10 days after delivery, and at 10–12 weeks postpartum. Mood scales included the Edinburgh Postnatal Depression Scale and the Depression, Anxiety and Stress Scale. Appraisal items addressed the experiences of pregnancy and motherhood. Results: Correlation and regression analyses showed a significant and stable association between symptoms of depression, anxiety and stress, and appraisals of low coping potential and future expectancy across the three assessment times. Low motivational congruence (incongruence) was associated with depression, anxiety, and stress during late pregnancy and the first days after childbirth, and with symptoms of depression at 10–12 weeks postpartum. Conclusion: In this sample of women experiencing low to moderate distress, findings suggest that the perceived ability to cope practically and emotionally with pregnancy and maternal-related issues, as well as pessimistic ideas about the future, form the core appraisal basis of perinatal distress. Implications for practice and intervention are discussed.     

Characterization of the acute pulse transit time response to obstructive apneas and hypopneas in preschool children with sleep-disordered breathing

Background

Surges in heart rate (HR) and blood pressure (BP) at apnea termination contribute to the hypertension seen in obstructive sleep apnea (OSA). Because childhood OSA prevalence peaks in the preschool years, we aimed to characterize the cardiovascular response to obstructive events in preschool-aged children.

Methods

Clinically referred children aged 3–5 years were grouped by obstructive apnea–hypopnea index (OAHI) into the following: primary snoring (PS) (OAHI ? 1 event/h [n = 21]), mild OSA (OAHI > 1– ? 5 [n = 32]), and moderate to severe (MS) OSA (OAHI > 5 [n = 28]). Beat-to-beat pulse transit time (PTT), an inverse continuous indicator of BP changes, and HR were averaged during the two halves (early and late) and during the peak after (post) each obstructive event and were expressed as percentage change from late- to post-event.

Results

We analyzed 422 events consisting of 55 apneas and 367 hypopneas. A significant post-event increase in HR and fall in PTT occurred in all severity groups (P < .05 for all). A greater response was associated with OSA, nonrapid eye movement sleep (NREM), cortical arousal, hypopneas, and oxygen desaturation (P < .05 for all).

Conclusions

Obstructive events elicit acute cardiovascular changes in preschool children. Such circulatory perturbations have been implicated in the development of hypertension, and our findings complement previous studies to suggest a cumulative impact of snoring on the cardiovascular system from childhood into adulthood.     

Platelet‐derived transforming growth factor‐β1 promotes keratinocyte proliferation in cutaneous wound healing

Platelets are a recognised potent source of transforming growth factor‐β1 (TGFβ1), a cytokine known to promote wound healing and regeneration by stimulating dermal fibroblast proliferation and extracellular matrix deposition. Platelet lysate has been advocated as a novel personalised therapeutic to treat persistent wounds, although the precise platelet‐derived growth factors responsible for these beneficial effects have not been fully elucidated. The aim of this study was to investigate the specific role of platelet‐derived TGFβ1 in cutaneous wound healing. Using a transgenic mouse with a targeted deletion of TGFβ1 in megakaryocytes and platelets (TGFβ1^fl/fl.PF4‐Cre), we show for the first time that platelet‐derived TGFβ1 contributes to epidermal and dermal thickening and cellular turnover after excisional skin wounding. In vitro studies demonstrate that human dermal fibroblasts stimulated with platelet lysate containing high levels of platelet‐derived TGFβ1 did not exhibit enhanced collagen deposition or proliferation, suggesting that platelet‐derived TGFβ1 is not a key promoter of these wound healing processes. Interestingly, human keratinocytes displayed enhanced TGFβ1‐driven proliferation in response to platelet lysate, reminiscent of our in vivo findings. In summary, our novel findings define and emphasise an important role of platelet‐derived TGFβ1 in epidermal remodelling and regeneration processes during cutaneous wound healing.     

Social class, smoking and the severity of respiratory symptoms in the general population

STUDY OBJECTIVE: The prevalence of respiratory symptoms has been found in some studies to vary with social class. One explanation of this link may be the effect of exposure to cigarette smoke. To investigate this, the relation between social class, smoking and respiratory symptoms was explored in a population based survey. DESIGN: A cross sectional survey using a validated questionnaire. SETTING: Two general practices in Staffordshire, United Kingdom. PATIENTS: A random sample of 4237 patients aged 16 and over from two general practices in Staffordshire were mailed a questionnaire enquiring about respiratory symptoms and their severity. MAIN RESULTS: The severity of respiratory symptoms increased with increasing exposure to cigarette smoke and was greater among manual social classes. Current smokers (odds ratio (OR) = 2.9, 95% confidence limits (CI) 2.3, 3.6), past smokers (OR = 1.5, 95% CI 1.2, 1.8) and passive smokers (OR = 1.4, 95% CI 1.0, 1.8) were more likely to report the more severe respiratory symptoms compared with non-smokers. Responders from social class V (OR = 2.4, 95% CI 1.3, 4. 4) were more likely to report the more severe respiratory symptoms compared with social class I, as were responders from social classes IIIM (OR = 1.3, 95% CI 0.9, 1.9) and IV (OR = 1.4, 95% CI 0.9, 2.1). These effects were independent of each other. CONCLUSIONS: This study has shown that social class is linked to the severity of respiratory symptoms, independently of smoking. Although the need to reduce and quit smoking in manual class households remains a crucial preventive issue, other mechanisms by which social class differences may influence symptom occurrence and severity need to be explored.