Concept: Limit superior and limit inferior
We present a case with outspoken spontaneous vestibular schwannoma shrinkage and review the related literature. The patient was initially diagnosed with a left-sided, intrameatal vestibular schwannoma, which subsequently grew into the cerebello-pontine angle (CPA), followed by total shrinkage of the CPA component without any intervention over a 12-year observation period. The literature on spontaneous tumor shrinkage was retrieved by searching the subject terms “vestibular schwannoma, conservative management” in PubMed/MEDLINE database, without a time limit. Of the published data, the articles on “shrinkage” or “negative growth” or “regression” or “involution” of the tumor were selected, and the contents on the rate, extent and mechanism of spontaneous tumor shrinkage were extracted and reviewed. The reported rate of spontaneous shrinkage of vestibular schwannoma is 5-10% of patients managed conservatively. Extreme shrinkage of the tumor may occur spontaneously.
PURPOSE OF REVIEW: This review provides an evidence-based comparison of aqueous shunts in common use. RECENT FINDINGS: Aqueous shunts are being used with increasing frequency in the surgical management of glaucoma. Recent retrospective studies and prospective clinical trials have compared the outcomes of different shunt designs. Larger end-plate size is associated with greater intraocular pressure (IOP) reduction, but there may be an upper limit beyond which a further increase in plate surface area does not contribute beneficially to pressure control. The biocompatibility of plate material may also influence shunt efficacy. The flow restrictor of the Ahmed glaucoma valve provides an added level of safety by reducing the risk of postoperative hypotony, but this implant also appears to have a higher incidence of bleb encapsulation. SUMMARY: Several aqueous shunts are commercially available, and all have been shown to be safe and effective in lowering IOP. Studies comparing aqueous shunts have provided valuable information to assist in surgical decision-making in similar patient groups.
- Journal of exposure science & environmental epidemiology
- Published almost 2 years ago
Buildings consume nearly 40% of primary energy production globally. Certified green buildings substantially reduce energy consumption on a per square foot basis and they also focus on indoor environmental quality. However, the co-benefits to health through reductions in energy and concomitant reductions in air pollution have not been examined.We calculated year by year LEED (Leadership in Energy and Environmental Design) certification rates in six countries (the United States, China, India, Brazil, Germany, and Turkey) and then used data from the Green Building Information Gateway (GBIG) to estimate energy savings in each country each year. Of the green building rating schemes, LEED accounts for 32% of green-certified floor space and publically reports energy efficiency data. We employed Harvard’s Co-BE Calculator to determine pollutant emissions reductions by country accounting for transient energy mixes and baseline energy use intensities. Co-BE applies the social cost of carbon and the social cost of atmospheric release to translate these reductions into health benefits. Based on modeled energy use, LEED-certified buildings saved $7.5B in energy costs and averted 33MT of CO2, 51 kt of SO2, 38 kt of NOx, and 10 kt of PM2.5 from entering the atmosphere, which amounts to $5.8B (lower limit = $2.3B, upper limit = $9.1B) in climate and health co-benefits from 2000 to 2016 in the six countries investigated. The U.S. health benefits derive from avoiding an estimated 172-405 premature deaths, 171 hospital admissions, 11,000 asthma exacerbations, 54,000 respiratory symptoms, 21,000 lost days of work, and 16,000 lost days of school. Because the climate and health benefits are nearly equivalent to the energy savings for green buildings in the United States, and up to 10 times higher in developing countries, they provide an important and previously unquantified societal value. Future analyses should consider these co-benefits when weighing policy decisions around energy-efficient buildings.
Cauda equina syndrome (CES) is a rare but important neurosurgical emergency. Despite being a recognised clinical entity since 1934, there remains significant uncertainty in the literature regarding the urgency for its surgical intervention. The past decade has seen the emergence of the much referred to 48-hour limit as a possible window of safety. The ramifications of this time-point are significant for early patients who may subsequently have urgent treatment delayed, and for litigation cases after which adverse decisions are more likely to occur.
A sensitive method for the simultaneous determination of isosorbide dinitrate (ISDN) and its mononitrate metabolites, isosorbide 2-mononitrate and isosorbide 5-mononitrate (IS-2-MN and IS-5-MN), in human plasma was developed using capillary gas chromatography with electron-capture detection, whereas 1,2,4-butanetriol trinitrate was used as internal standard. The analytes were extracted with a simple liquid-liquid extraction from plasma and separated on a DB-1 column. The results of method validation demonstrated that the calibration curves were linear in range of 2-60 ng/mL for ISDN and IS-5-MN, 1-20 ng/mL for IS-2-MN, respectively. The precision (RSD%) was less than 15%, and the lower limit of quantitation was identifiable and reproducible at 2 ng/mL for ISDN and IS-5-MN, 1 ng/mL for IS-2-MN. The analytes in plasma were stable after being stored for more than 30 days and after 2 freeze-thaw cycles (-20 to 25°C). And then this method was successfully applied to a pharmacokinetic investigation on isosorbide dinitrate oral spray in healthy volunteers.
The upper limit of the cardiorespiratory training zone (40-84%HRR) is overestimated for postmenopausal women
- Journal of science and medicine in sport / Sports Medicine Australia
- Published almost 7 years ago
Objective The purpose of this study was to examine the heart rate reserve (HRR) at first and second ventilatory thresholds (VT’s) in postmenopausal women and compare it with optimal intensity range recommended by the ACSM (40-84%HRR). An additional aim was to evaluate whether a higher aerobic power level corresponded to a higher HRR at VT’s. Methods Fifty-eight postmenopausal women participated in this study (aged 48-69). A graded 25Wmin(-2) cycle ergometer (Monark E839) exercise protocol was performed in order to assess aerobic power. The heart rate and gas-exchange variables were measured continuously using a portable gas analyzer system (Cosmed K4b). The first (VT(1)) and the second (VT(2)) VT’s were determined by the time course curves of ventilation and O(2) and CO(2) ventilatory equivalents. A K-means clustering analysis was used in order to identify VO(2max) groups (cut-off of 30.5mlkg(-1)min(-1)) and differences were evaluated by an independent sample t-test. Bland-Altman plots were performed to illustrate the agreement between methods. Results The women’s HRR values at VT(1) were similar to 40%HRR in both VO(2max) groups. At VT(2) both VO(2max) groups exhibited negative differences (P<0.01) for the predicted 84%HRR intensity (-14.46% in the lower VO(2max) group and -16.32% in the higher VO(2max) group). Conclusions An upper limit of 84% overestimates the %HRR value for the second ventilatory threshold, suggesting that the cardiorespiratory target zone for this population should be lower and narrower (40-70%HRR).
Although liquids typically flow around intruding objects, a counterintuitive phenomenon occurs in dense suspensions of micrometre-sized particles: they become liquid-like when perturbed lightly, but harden when driven strongly. Rheological experiments have investigated how such thickening arises under shear, and linked it to hydrodynamic interactions or granular dilation. However, neither of these mechanisms alone can explain the ability of suspensions to generate very large, positive normal stresses under impact. To illustrate the phenomenon, such stresses can be large enough to allow a person to run across a suspension without sinking, and far exceed the upper limit observed under shear or extension. Here we show that these stresses originate from an impact-generated solidification front that transforms an initially compressible particle matrix into a rapidly growing jammed region, ultimately leading to extraordinary amounts of momentum absorption. Using high-speed videography, embedded force sensing and X-ray imaging, we capture the detailed dynamics of this process as it decelerates a metal rod hitting a suspension of cornflour (cornstarch) in water. We develop a model for the dynamic solidification and its effect on the surrounding suspension that reproduces the observed behaviour quantitatively. Our findings suggest that prior interpretations of the impact resistance as dominated by shear thickening need to be revisited.
- The Journal of clinical endocrinology and metabolism
- Published over 6 years ago
Context:Studies examining the association between subclinical hypothyroidism and mortality have yielded conflicting results. Emerging data suggest these associations may depend upon underlying congestive heart failure (CHF) and/or race, but this has not been empirically determined.Objective:Our objective was to examine the association between subclinical hypothyroidism and hypothyroidism overall with mortality according to pre-existing CHF and race.Design and Participants:We examined the associations of subclinical hypothyroidism (TSH higher than assay upper limit of normal; total T4 within reference) and hypothyroidism overall (TSH higher than assay upper limit of normal; total T4 below lower limit of normal or within reference) with all-cause mortality among Third National Health and Nutrition Examination Survey participants stratified by CHF and race using multivariable Cox models. To confirm whether differences between strata were statistically significant, we tested for interaction on the basis of CHF (separately) and race by likelihood ratio testing.Results:There were 14ü130 (95.0%) euthyroid controls and 749 (5.0%) participants with hypothyroidism, 691 (4.6%) of whom had subclinical disease. Subclinical hypothyroidism vs euthyroidism was associated with greater mortality in those with CHF but not in those without: adjusted hazard ratios (HRs) (95% confidence intervals [CIs]) = 1.44 (1.01-2.06) and 0.97 (0.85-1.11), respectively (P interaction = .03). Similar findings were observed for hypothyroidism overall. Hypothyroidism overall vs euthyroidism was associated with greater mortality in Black participants (HR = 1.44 [95% CI = 1.03-2.03]) but not in non-Blacks (HR = 0.95 [95% CI = 0.83-1.08]) (P interaction = .03).Conclusion:Among participants with CHF, subclinical hypothyroidism and hypothyroidism overall are associated with greater death risk. Additional studies are needed to confirm findings and explore possible mechanisms for the differential hypothyroidism-mortality association across race.
Single-point measurements of maximal inspiratory pressure (MIP) are frequently used to suggest muscle weakness in clinical practice. Although there is a large variability in “mean” predicted MIP depending on the chosen reference values, it remains unclear whether those discrepancies actually impact on the prevalence of weakness, i.e., MIP below the lower limit of normal.
A new analytical strategy was developed that integrates a generic sample preparation into a liquid chromatography-multistage ion trap/time-of-flight mass spectrometry (LC-IT(MSn)/TOF), allowing for large-scale screening and qualitative confirmation of wide-scope illegal adulterants in different food matrices. Samples were pretreated by a fast single-tube multi-function extraction for accurate multistage mass measurement on the hybrid LC-IT/TOF system. A qualitative validation performed for over 500 analyte-matrix pairs showed the method can reduce most of the matrix effects and achieve a lower limit of confirmation at 0.1 mg/kg for 73% of the target compounds. An unique combination of dual-polarity detection, retention time, isotopic profile and accurate MSn spectra enables more comprehensive and precise confirmation, based on the multiparameter matching by automated library searching against the user-created database. Finally we demonstrated the applicability of this LC-IT(MSn)/TOF-based screening procedure for discriminating coeluting isobars, identifying nontarget adulterants, and even tentatively elucidating unexpected species in real samples.