Vascular transit time (VTT) is the propagation time of a pulse wave through an artery; it is a measure for arterial stiffness. Because reliable non-invasive VTT measurements are difficult, as an ...alternative we measure pulse transit time (PTT). PTT is defined as the time between the R-wave on electrocardiogram and arrival of the resulting pulse wave in a distal location measured with photoplethysmography (PPG). The time between electrical activation of the ventricles and the resulting pulse wave after opening of the aortic valve is called the pre-ejection period (PEP), a component of PTT. The aim of this study was to estimate the variability of PEP at rest, to establish how accurate PTT is as approximation of VTT.
PTT was measured and PEP was assessed with echocardiography (gold standard) in three groups of 20 volunteers: 1) a control group without cardiovascular disease aged <50 years and 2) aged >50 years, and 3) a group with cardiovascular risk factors, defined as arterial hypertension, dyslipidemia, kidney failure and diabetes mellitus.
Per group, the mean PEP was: 1) 58.5 ± 13.0 ms, 2) 52.4 ± 11.9 ms, and 3) 57.6 ± 11.6 ms. However, per individual the standard deviation was much smaller, i.e. 1) 2.0-5.9 ms, 2) 2.8-5.1 ms, and 3) 1.6-12.0 ms, respectively. There was no significant difference in the mean PEP of the 3 groups (p = 0.236).
In conclusion, the intra-individual variability of PEP is small. A change in PTT in a person at rest is most probably the result of a change in VTT rather than of PEP. Thus, PTT at rest is an easy, non-invasive and accurate approximation of VTT for monitoring arterial stiffness.
We examine POLAR data for several cusp crossings, observing two different types of cusp-like regions. We apply the label 'quiet cusp'to the traditional cusp of high-density, stagnant solar wind ...plasma. 'Cusp Diamagnetic Cavities', described previously, are similar but show a strongly depressed and turbulent field and are colocated with 'Cusp Energetic Particle' observations. Within the CDC's, field depressions are strongly correlated to enhancements in the local plasma density.
Interplanetary magnetic flux ropes with durations from a few minutes to a few hours have been termed small flux ropes (SFRs). We have built a comprehensive catalog of SFRs at Mercury using ...magnetometer data from the orbital phase of the MESSENGER mission (2011-2015). In the absence of solar wind plasma measurements, we developed strict identification criteria for SFRs in the magnetometer observations, including force-free field fits for each flux rope. We identified a total of 48 events that met our strict criteria, with events ranging in duration from 2.5 minutes to 4 hr. Using superposed epoch analysis, we obtained the generic SFR magnetic field profile at Mercury. Due to its eccentric orbit, Mercury's heliospheric distance varies between 0.31 and 0.47 au, a range of ∼0.16 au. This distance is potentially large enough for the SFRs to undergo measurable changes due to distance. Thus, we split the data into two distance bins to look for such changes. We found that the average SFR profile is more symmetric farther from the Sun, in line with the idea that SFRs form closer to the Sun and undergo a relaxation process in the solar wind. Based on this result, as well as the SFR durations and the magnetic field strength fall-off with heliocentric distance, we infer that the SFRs observed at Mercury are expanding as they propagate with the solar wind. We also determined that the SFR occurrence frequency is nearly four times as high at Mercury as for similarly detected events at 1 au. Most interestingly, we found two SFR populations in our data set, one likely generated in a quasi-periodic formation process near the heliospheric current sheet, and the other formed away from the current sheet in isolated events.
Osteonecrosis of the femoral head (ONFH) is a devastating disease of the hip joint. Its early diagnosis is crucial to increase the chances of joint preserving, yet difficult due to similarities with ...osteoarthritis (OA) of the hip in its clinical appearance. The purpose of this study was to enhance the understanding of ONFH and its pathologic processes in contrast to OA and to identify serum biomarkers helping to improve the diagnosis of the disease.
Bone and bone marrow samples were collected from 24 patients diagnosed with OA and 25 patients with ONFH during total hip replacement surgery. RNA was isolated, histological examination, determination of free reactive oxygen species as well as gene expression and biomarker analysis were performed.
Histological analysis revealed differences in the structural and cellular pattern between the groups. Gene expression analysis revealed a significant upregulation for the genes ASPN, COL1A1, COL2A1 and IL6 and a significant downregulation for HIF1A in ONFH compared to OA group. Analysis of serum biomarkers showed significant differences between the groups for asporin and adiponectin. A final logistical regression model including the parameters adiponectin, asporin and HIF 1α was overall significant, explained 34.5 % of variance and classified 74.5 % of the cases correctly.
The combination of adiponectin, asporin and HIF 1α as serum biomarkers revealed a classification accuracy of 74.5 %. The information provided in this study may help to enhance the understanding of pathologic processes in ONFH and to elaborate further aspects of prediction and treatment.
Abstract Introduction/Aims Corneal confocal microscopy (CCM) detects small nerve fiber loss and correlates with skin biopsy findings in diabetic neuropathy. In chronic idiopathic axonal ...polyneuropathy (CIAP) this correlation is unknown. Therefore, we compared CCM and skin biopsy in patients with CIAP to healthy controls, patients with painful diabetic neuropathy (PDN) and diabetics without overt neuropathy (DM). Methods Participants with CIAP and suspected small fiber neuropathy ( n = 15), PDN ( n = 16), DM ( n = 15), and healthy controls ( n = 16) underwent skin biopsy and CCM testing. Inter‐center intraclass correlation coefficients (ICC) were calculated for CCM parameters. Results Compared with healthy controls, patients with CIAP and PDN had significantly fewer nerve fibers in the skin (IENFD: 5.7 ± 2.3, 3.0 ± 1.8, 3.9 ± 1.5 fibers/mm, all p < .05). Corneal nerve parameters in CIAP (fiber density 23.8 ± 4.9 no./mm 2 , branch density 16.0 ± 8.8 no./mm 2 , fiber length 13.1 ± 2.6 mm/mm 2 ) were not different from healthy controls (24.0 ± 6.8 no./mm 2 , 22.1 ± 9.7 no./mm 2 , 13.5 ± 3.5 mm/mm 2 , all p > .05). In patients with PDN, corneal nerve fiber density (17.8 ± 5.7 no./mm 2 ) and fiber length (10.5 ± 2.7 mm/mm 2 ) were reduced compared with healthy controls ( p < .05). CCM results did not correlate with IENFD in CIAP patients. Inter‐center ICC was 0.77 for fiber density and 0.87 for fiber length. Discussion In contrast to patients with PDN, corneal nerve parameters were not decreased in patients with CIAP and small nerve fiber damage. Therefore, CCM is not a good biomarker for small nerve fiber loss in CIAP patients.
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