3D Assessment of Cortical Bone Porosity and Tissue Mineral Density Using High‐Resolution µCT: Effects of Resolution and Threshold Method

Current micro–computed tomography (µCT) systems allow scanning bone at resolutions capable of three‐dimensional (3D) characterization of intracortical vascular porosity and osteocyte lacunae. However, the scanning and reconstruction parameters along with the image segmentation method affect the accuracy of the measurements. In this study, the effects of scanning resolution and image threshold method in quantifying small features of cortical bone (vascular porosity, vascular canal diameter and separation, lacunar porosity and density, and tissue mineral density) were analyzed. Cortical bone from the tibia of Sprague‐Dawley rats was scanned at 1‐µm and 4‐µm resolution, reconstructions were density‐calibrated, and volumes of interest were segmented using approaches based on edge‐detection or histogram analysis. In 1‐µm resolution scans, the osteocyte lacunar spaces could be visualized, and it was possible to separate the lacunar porosity from the vascular porosity. At 4‐µm resolution, the vascular porosity and vascular canal diameter were underestimated, and osteocyte lacunae were not effectively detected, whereas the vascular canal separation and tissue mineral density were overestimated compared to 1‐µm resolution. Resolution had a much greater effect on the measurements than did threshold method, showing partial volume effects at resolutions coarser than 2 µm in two separate analyses, one of which assessed the effect of resolution on an object of known size with similar architecture to a vascular pore. Although there was little difference when using the edge‐detection versus histogram‐based threshold approaches, edge‐detection was somewhat more effective in delineating canal architecture at finer resolutions (1–2 µm). In addition, use of a high‐resolution (1 µm) density‐based threshold on lower resolution (4 µm) density‐calibrated images was not effective in improving the lower‐resolution measurements. In conclusion, if measuring cortical vascular microarchitecture, especially in small animals, a µCT resolution of 1 to 2 µm is appropriate, whereas a resolution of at least 1 µm is necessary when assessing osteocyte lacunar porosity. © 2014 American Society for Bone and Mineral Research.     

Hyperhomocysteinemia exacerbates the development of intimal hyperplasia in Sprague-Dawley rats: Alleviation by rosiglitazone

The amino acid intermediate homocysteine (Hcy) is formed during the metabolism of methionine to cysteine. Hyperhomocysteinemia (HHcy) is recognized as an independent risk factor for coronary atherosclerosis. The circulating levels of total Hcy (tHcy) can increase due to intake of foods rich in methionine or deficiencies of vitamins such as folate, pyridoxine and cyanocobalamin, which are required for the metabolism of Hcy. In addition, mutations in the genes coding for Hcy metabolizing enzymes can contribute to an increase in tHcy levels. Clinical and epidemiological studies have shown that an elevated level of tHcy measured in serum or plasma is a strong predictor of cardiovascular disease risk, which appears to be greatest in patients who have HHcy following a methionine load. Intimal hyperplasia (IH) (intima/media [I/M] ratio) is the universal response of a vessel to injury and may result in vasoconstriction when left unattended. The effect of dietary HHcy on balloon catheter-injured carotid artery and its modulation (if any) by the peroxisome proliferator-activated receptor agonist gamma rosiglitazone was evaluated in 12-week-old female Sprague-Dawley rats fed either a control diet or a diet containing 1% L-methionine. Once the rats were established on the diet, the group that was fed 1% L-methionine was further subdivided and either given an aqueous preparation of 3 mg/kg/day rosiglitazone or the vehicle via oral gavage for one week. This was followed by surgically injuring the left carotid artery using a Maverick Over-The-Wire catheter (2.0 mm × 20 mm, 3.2F; Boston Scientific, USA). The rats were continued on their respective diets and drug regimen for 21 days postsurgery. On day 22 of the procedure, the rats were sacrificed for collection of blood, the carotid arteries and liver for biochemical and histological evaluation. Compared with controls there was a significant increase in both tHcy levels and I/M ratio in the rats fed 1% L-methionine (5.4±0.28 μM versus 32.8±3.01 μM, P<0.002; and 0.175±0.05 versus 1.05±0.23, P<0.005, respectively). The effect of rosiglitazone in rats fed the control diet was not prominent. On the other hand, administration of rosiglitazone to the rats on the 1% L-methionine diet significantly reduced the levels of serum tHcy (16.6±2.1 μM versus 32.8±3.01 μM, P<0.001); however, the tHcy levels remained significantly elevated compared with animals on the control diet (P<0.002). The group receiving the L-methionine diet plus rosiglitazone had an inhibition in the development of IH compared with those receiving the L-methionine diet alone (I/M of 0.278±0.041 versus 1.05±0.23, P<0.01). Moreover, the development of IH in the group receiving the L-methionine diet plus rosiglitazone treatment was not significantly different from that observed in the group on the control diet without rosiglitazone (0.278±0.041 versus 0.175±0.05, respectively). These findings may have important implications in deciphering the molecular mechanisms involved in the augmentation of IH in HHcy and modulation of this process by rosiglitazone.     

社区医护干预预防产后抑郁症的研究

[目的]调查产后抑郁症患者的现状及需求,探讨预防措施。[方法]定性与定量研究相结合,定性采用专题小组讨论和半结构性访谈,12人参加专题讨论、9人半结构性访谈;定量研究随机抽取本市各社区产后42d的产妇776例行问卷调查。[结果]产妇月子期间常发生头疼、恶心、焦虑、恐惧、失眠以及照顾新生儿困难;半结构性访谈中有1产妇处于产后抑郁症的临界,EPDS量表测定为12分;776例产妇月子里有身心健康问题者692例,求助者91.0%,其中需要社区护理人员帮助的71.7%,实际寻求帮助仅12.7%。[结论]预防产后抑郁症应实行社区医护人员培训与产后访视人员的准入制度,采取社区医护干预的三级预防,同时拓展社区产后保健服务的内涵。     

Objective screening for olfactory and gustatory dysfunction during the COVID‐19 pandemic: A prospective study in healthcare workers using self‐administered testing

BackgroundSmell and taste loss are highly prevalent symptoms in coronavirus disease 2019 (COVID‐19), although few studies have employed objective measures to quantify these symptoms, especially dysgeusia. Reports of unrecognized anosmia in COVID‐19 patients suggests that self‐reported measures are insufficient for capturing patients with chemosensory dysfunction.ObjectivesThe purpose of this study was to quantify the impact of recent COVID‐19 infection on chemosensory function and demonstrate the use of at‐home objective smell and taste testing in an at‐risk population of healthcare workers.MethodsTwo hundred and fifty healthcare workers were screened for possible loss of smell and taste using online surveys. Self‐administered smell and taste tests were mailed to respondents meeting criteria for elevated risk of infection, and one‐month follow‐up surveys were completed.ResultsAmong subjects with prior SARS‐CoV‐2 infection, 73% reported symptoms of olfactory and/or gustatory dysfunction. Self‐reported smell and taste loss were both strong predictors of COVID‐19 positivity. Subjects with evidence of recent SARS‐CoV‐2 infection (<45 days) had significantly lower olfactory scores but equivalent gustatory scores compared to other subjects. There was a time‐dependent increase in smell scores but not in taste scores among subjects with prior infection and chemosensory symptoms. The overall infection rate was 4.4%, with 2.5% reported by PCR swab.ConclusionHealthcare workers with recent SARS‐CoV‐2 infection had reduced olfaction and normal gustation on self‐administered objective testing compared to those without infection. Rates of infection and chemosensory symptoms in our cohort of healthcare workers reflect those of the general public.     

Presence of both odor identification and detection deficits in Alzheimer's disease

Recent studies of Alzheimer's disease patients have demonstrated (a) marked structural and biochemical alterations in brain regions associated with olfactory function (including the olfactory bulb and entorhinal cortex) and (b) decrements in the ability to identify odorants. In light of such findings, we administered the University of Pennsylvania Smell Identification Test (UPSIT) and a forced-choice phenyl ethyl alcohol odor detection threshold test to a relatively large number of patients diagnosed, on the basis of stringent criteria, as having mild to moderately severe Alzheimer's disease. Compared to age-, gender-, and race-matched normal controls, these individuals evidenced consistent and marked decrements on both types of olfactory tests (ps less than 0.001). Surprisingly few of the patients were aware of their disorder, despite its appearance early in the disease process. These findings indicate that both odor identification and odor detection problems are present in dementia of the Alzheimer's type, and raise the possibility that the odor identification problem may be secondary to the odor detection problem.     

Intermetallics Formation during Solidification of Al-Si-Cu-Mg Cast Alloys

The present study was undertaken to examine the effect of iron, manganese, copper and magnesium on the microstructural characteristics of Al-11%Si-2%Cu-Mg-based alloy referred to as 396 under different working conditions. The results show that strontium (Sr) has high affinity to react with magnesium (Mg), resulting in reduced effectiveness as eutectic silicon modifier or age hardening agent. In addition, Sr alters the sequence of the precipitation of the α-AlFeMnSi phase from post-eutectic to pro-eutectic which would harden the soft α-Aluminum matrix. The mechanism is still under investigation. The interactions between iron (Fe) and Mg and Sr-Mg result in the formation of serval dissolvable intermetallics during the solutionizing treatment such as β-AlFeSi, π-AlFeMgSi and Q-AlMgSiCu phases. The study also emphasizes the role of modification and grain refining as well as intermetallics in porosity formation and hardness of samples aged in the temperature range 155–240 °C.