This study presents an updated and homogenised ozone time series covering 34 years (1987–2020) of ozonesonde measurements at Lauder, New Zealand, and attributes vertically resolved ozone trends using ...a multiple linear regression (MLR) analysis and a chemistry–climate model (CCM). Homogenisation of the time series leads to a marked difference in ozone values before 1997, in which the ozone trends are predominantly negative from the surface to ∼ 30 km, ranging from ∼ −2 % per decade to −13 % per decade, maximising at around 12–13 km, in contrast to the uncorrected time series which shows no clear trends for this period. For the post-2000 period, ozone at Lauder shows negative trends in the stratosphere, maximising just below 20 km (∼ −5 % per decade) despite the fact that stratospheric chlorine and bromine from ozone-depleting substances (ODSs) have both been declining since 1997. However, the ozone trends change from negative for 1987–1999 to positive in the post-2000 period in the free troposphere. The post-2000 ozone trends calculated from the ozonesonde measurements compare well with those derived from the co-located low-vertical-resolution Fourier-transform infrared spectroscopy (FTIR) ozone time series. The MLR analysis identifies that the increasing tropopause height, associated with CO2-driven dynamical changes, is the leading factor driving the continuous negative trend in lower-stratospheric ozone at Lauder over the whole observational period, whilst the ozone-depleting substances (ODSs) only contribute to the negative ozone trend in the lower stratosphere over the pre-1999 period. Meanwhile, stratospheric temperature changes contribute significantly to the negative ozone trend above 20 km over the post-2000 period. Furthermore, the chemistry–climate model (CCM) simulations that separate the effects of individual forcings show that the predominantly negative modelled trend in ozone for the 1987–1999 period is driven not only by ODSs but also by increases in greenhouse gases (GHGs), with large but opposing impacts from methane (positive) and CO2 (negative), respectively. Over the 2000–2020 period, the model results show that the CO2 increase is the dominant driver for the negative trend in the lower stratosphere, in agreement with the MLR analysis. Although the model underestimates the observed negative ozone trend in the lower stratosphere for both periods, it clearly shows that CO2-driven dynamical changes have played an increasingly important role in driving the lower-stratospheric ozone trends in the vicinity of Lauder.
Starting in 1969 and comprising three launches a week, the
Uccle (Brussels, Belgium) ozonesonde dataset is one of longest and densest
in the world. Moreover, as the only major change was the switch ...from
Brewer-Mast (BM) to electrochemical concentration cell (ECC) ozonesonde
types in 1997 (when the emissions of ozone-depleting substances peaked), the Uccle time series is very homogenous. In this paper, we briefly describe the efforts that were undertaken during the first 3 decades of the 50 years
of ozonesonde observations to guarantee the homogeneity between ascent and
descent profiles, under changing environmental conditions (e.g. SO2),
and between the different ozonesonde types. This paper focuses on the 50-year-long Uccle ozonesonde dataset and aims to demonstrate its past,
present, and future relevance to ozone research in two application areas: (i) the assessment of the temporal evolution of ozone from the surface to the
(middle) stratosphere, and (ii) as the backbone for validation and stability
analysis of both stratospheric and tropospheric satellite ozone
retrievals. Using the Long-term Ozone Trends and Uncertainties in the
Stratosphere (LOTUS) multiple linear regression model (SPARC/IO3C/GAW,
2019), we found that the stratospheric ozone concentrations at Uccle
have declined at a significant rate of around 2 % per decade since 1969, which is also rather
consistent over the different stratospheric levels. This overall decrease
can mainly be assigned to the 1969–1996 period with a rather consistent
rate of decrease of around −4 % per decade. Since 2000, a recovery of between +1 % per decade and +3 % per decade of the stratospheric ozone levels above Uccle has been
observed, although it is not significant and is not seen for the upper stratospheric
levels measured by ozonesondes. Throughout the entire free troposphere, a
very consistent increase in the ozone concentrations of 2 % per decade to 3 % per decade has been measured since both 1969 and 1995, with the trend since 1995 being in
almost perfect agreement with the trends derived from the In-service
Aircraft for a Global Observing System (IAGOS) ascent/descent profiles at
Frankfurt. As the number of tropopause folding events in the Uccle time
series has increased significantly over time, increased
stratosphere-to-troposphere transport of recovering stratospheric ozone
might partly explain these increasing tropospheric ozone concentrations,
despite the levelling-off of (tropospheric) ozone precursor emissions and
notwithstanding the continued increase in mean surface ozone concentrations.
Furthermore, we illustrate the crucial role of ozonesonde measurements for
the validation of satellite ozone profile retrievals. With the operational
validation of the Global Ozone Monitoring Experiment-2 (GOME-2), we show how the
Uccle dataset can be used to evaluate the performance of a degradation
correction for the MetOp-A/GOME-2 UV (ultraviolet) sensors. In another example, we
illustrate that the Microwave Limb Sounder (MLS) overpass ozone profiles in
the stratosphere agree within ±5 % with the Uccle ozone profiles
between 10 and 70 hPa. Another instrument on the same Aura satellite
platform, the Tropospheric Emission Spectrometer (TES), is generally positively
biased with respect to the Uccle ozonesondes in the troposphere by up to
∼ 10 ppbv, corresponding to relative differences of up to
∼ 15 %. Using the Uccle ozonesonde time series as a
reference, we also demonstrate that the temporal stability of those last two satellite retrievals is excellent.
Although in principle ECC (electrochemical concentration cell) ozonesondes are absolute measuring devices, in practice they have several “artefacts” which change over the course of a flight. Most of ...the artefacts have been corrected in the recommendations of the Assessment of Standard Operating Procedures for Ozone Sondes (ASOPOS) report (Smit et al., 2021), giving an overall uncertainty of 5 %–10 % throughout the profile. However, the conversion of the measured cell current into the sampled ozone concentration still needs to be quantified better, using time-varying background current and more appropriate pump efficiencies. We describe an updated methodology for ECC sonde data processing that is based on the Jülich Ozone Sonde Intercomparison Experiment (JOSIE) 2009/2010 and JOSIE Southern Hemisphere Additional Ozonesondes (JOSIE-SHADOZ) 2017 test chamber data. The methodology resolves the slow and fast time responses of the ECC ozonesonde and in addition applies calibration functions to make the sonde data traceable to the JOSIE ozone reference UV photometer (OPM). The stoichiometry (O3/I2) factors and their uncertainties along with fast and slow reaction pathways for the different sensing solution types used in the global ozonesonde network are determined. Experimental evidence is given for treating the background current of the ECC sensor as the superposition of a constant ozone-independent component (IB0, measured before ozone exposure in the sonde preparation protocol) and a slow time-variant ozone-dependent current determined from the initial measured ozone current using a first-order numerical convolution. The fast sensor current is refined using the time response determined in sonde preparation with a first-order deconvolution scheme. Practical procedures for initializing the numerical deconvolution and convolution schemes to determine the slow and fast ECC currents are given. Calibration functions for specific ozonesondes and sensing solution type combinations were determined by comparing JOSIE 2009/2010 and JOSIE-SHADOZ 2017 profiles with the JOSIE OPM. With fast and slow currents resolved and the new calibration functions, a full uncertainty budget is obtained. The time response correction methodology makes every ozonesonde record traceable to one standard, i.e. the OPM of JOSIE, enabling the goal of a 5 % relative uncertainty to be met throughout the global ozone network.
Local anesthetics and alcohols block impulse conduction in peripheral nerves by inhibiting Na(+) currents. In small peripheral nerve fibers, tetrodotoxin-resistant (TTX-r) Na(+) channels play an ...important role in impulse generation. We investigated the effects of lidocaine and the alcohol octanol on TTX-r Na(+) channels. Currents were recorded with the whole-cell patch-clamp method from enzymatically isolated rat dorsal root ganglion cells (data evaluation: nonlinear least-squares fitting). Lidocaine and octanol blocked the TTX-r Na(+) current in a reversible and concentration-dependent manner (50% inhibitory concentration values: 177 +/- 25 and 455 +/- 25 microM, respectively). Lidocaine additionally produced a strong use-dependent block. Both drugs showed a strong dynamic block (i.e., block developed during the time course of current activation and inactivation). Double-pulse protocols showed a slow dissociation of lidocaine from the channel during repolarization (time constant: 1763 +/- 63 ms; 300 microM). The dissociation of octanol was too quick to be distinguished from normal current repriming kinetics of 2.2 ms. Lidocaine and octanol acted noncompetitively in the Na(+) channel. Lidocaine and octanol have different blocking properties on the TTX-r Na(+) current and bind to different channel sites.
Lidocaine and octanol have different inhibitory effects on the function of tetrodotoxin-resistant Na(+) channels in rat dorsal root ganglion cells, as well as noncompetitive modes of action, as investigated by the whole-cell patch-clamp method, and therefore are likely to have different binding sites on the channel.
Although monocyte chemoattractant protein-1 (MCP-1) levels are increased in patients with ST-segment elevation myocardial infarction, the prognostic value of MCP-1 in primary percutaneous coronary ...intervention (pPCI) is not clear. The goal of the present study was to investigate the association of MCP-1 levels with myocardial perfusion and prognosis in patients with ST-segment elevation myocardial infarction undergoing pPCI. Consecutive pPCI patients (n = 192) were assigned to tertiles according to their admission serum MCP-1 levels. Angiographic no-reflow, Thrombolysis In Myocardial Infarction flow grade, myocardial blush grade, and ST-segment resolution were assessed. Mortality and major adverse cardiac events were evaluated during hospitalization and at the 3-year clinical follow-up visit. Failure of ST resolution was associated with greater admission MCP-1 levels. The risk of no-reflow (Thrombolysis In Myocardial Infarction flow ≤2 or Thrombolysis In Myocardial Infarction flow 3 with final myocardial blush grade ≤2 after pPCI and ST resolution <30%) increased as the admission MCP-1 increased. The 3-year mortality increased as the MCP-1 level increased (8% vs 22% vs 28% for the 3 tertiles, p <0.01). Multivariate logistic regression analysis demonstrated that MCP-1 levels at admission are a significant independent correlate of 3-year mortality in patients with no-reflow as detected by myocardial blush grade. A receiver operating characteristics analysis identified an optimum cut point of ≥254 pg/ml, which was associated with a negative predictive value of 95% in association with 1-year mortality. In conclusion, the plasma MCP-1 levels at admission are independently associated with the development of no-reflow and 3-year mortality in patients with ST-segment elevation myocardial infarction undergoing pPCI.
Background Although the incidence of caustic ingestion is declining, the management of caustic esophageal strictures remains a challenge. Although many agents have been tried experimentally to treat ...strictures, few have gained clinical application. The aim of this study was to investigate the influence of mitomycin C (MMC), which inhibits fibroblastic proliferation in treating delayed caustic esophageal strictures. Methods Forty-two rats were allocated into 3 groups. Caustic esophageal burns were created as described by Gehanno. Group A was instilled only with saline. Group B was injured with 10% NaOH and left untreated. Group C was injured and received topical MMC at 0.04% concentration in the fourth week. At 56 days, stenosis index (SI), collagen deposition, and hydroxyproline content (HP) were determined in distal esophageal segments. Statistical analyses were performed. Results The mean SI in group B was significantly higher than others (SI: 1.15 ± 0.37 d/lum, P < .05). Collagen accumulation was highest in group B, followed by groups C and A, respectively. Collagen deposition in group C was statistically lower than group B ( P < .018). The mean HP in group B was statistically higher than others (5.07 ± 1.30 μg/mg tissue, P < .05), and similar between groups A and C (1.20 ± 0.20, 1.91± 0.79, respectively, P = .73). Conclusion In the current study, MMC treatment ameliorated caustic esophageal stricture as reflected in the significantly lower SI. We conclude that MMC application is effective in the treatment of caustic esophageal strictures.
Abstract Background Symptomatic cardiac injury after blunt chest trauma is relatively rare, and valvular injury is even more rare. The valves most commonly affected are tricuspid. Automobile ...accidents are mostly responsible for this type of injury. Objectives Unlike with the mitral valve, post-traumatic tricuspid heart valve insufficiency is usually well tolerated. Indeed, severe tricuspid regurgitation can resolve spontaneously. Case Report A 68-year-old woman with no previous cardiac or medical history was brought to our Emergency Department after an automobile accident. She had chest pain and shortness of breath upon admission. Transthoracic echocardiographic examination revealed severe tricuspid regurgitation with rupture of the chordae tendineae and prolapse of the valve cusps into the right atrium during systole. An electrocardiogram was consistent with second-degree Mobitz II atrioventricular block on admission, which subsequently progressed to complete atrioventricular block on day 3. During follow-up with close hemodynamic monitoring, her symptoms disappeared and repeat echocardiography revealed a regression in the severity of tricuspid regurgitation. Operative repair of the tricuspid valve was deemed unnecessary and the patient was discharged with medical therapy on the eighth day after admission. Conclusions It is important to be aware of traumatic tricuspid regurgitation after non-penetrating chest trauma. Close follow-up may suffice in some patients with stable hemodynamic conditions, and regression of tricuspid regurgitation can be expected during follow-up.
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