BackgroundA growing number of studies linked elevated concentrations of circulating asymmetric (ADMA) and symmetric (SDMA) dimethylarginine to mortality and cardiovascular disease (CVD) events. To summarize the evidence, we conducted a systematic review and quantified associations of ADMA and SDMA with the risks of all-cause mortality and incident CVD in meta-analyses accounting for different populations and methodological approaches of the studies.MethodsRelevant studies were identified in PubMed until February 2015. We used random effect models to obtain summary relative risks (RR) and 95% confidence intervals (95%CIs), comparing top versus bottom tertiles. Dose-response relations were assessed by restricted cubic spline regression models and potential non-linearity was evaluated using a likelihood ratio test. Heterogeneity between subgroups was assessed by meta-regression analysis.ResultsFor ADMA, 34 studies (total n = 32,428) investigating associations with all-cause mortality (events = 5,035) and 30 studies (total n = 30,624) investigating the association with incident CVD (events = 3,396) were included. The summary RRs (95%CI) for all-cause mortality were 1.52 (1.37–1.68) and for CVD 1.33 (1.22–1.45), comparing high versus low ADMA concentrations. Slight differences were observed across study populations and methodological approaches, with the strongest association of ADMA being reported with all-cause mortality in critically ill patients. For SDMA, 17 studies (total n = 18,163) were included for all-cause mortality (events = 2,903), and 13 studies (total n = 16,807) for CVD (events = 1,534). High vs. low levels of SDMA, were associated with increased risk of all-cause mortality [summary RR (95%CI): 1.31 (1.18–1.46)] and CVD [summary RR (95%CI): 1.36 (1.10–1.68) Strongest associations were observed in general population samples.ConclusionsThe dimethylarginines ADMA and SDMA are independent risk markers for all-cause mortality and CVD across different populations and methodological approaches.

The medullary thick ascending limb of Henle's loop (mTAL) is crucial for urine-concentrating ability of the kidney. It is water tight and able to dilute the luminal fluid by active transcellular NaCl transport, fueling the counter current mechanism by increasing interstitial osmolality. While chloride is exclusively transported transcellularly, approx. 50% of sodium transport occurs via the paracellular route, driven by the lumen-positive transepithelial potential. Antidiuretic hormone (AVP) is known to increase active NaCl transport to support collecting duct water reabsorption. Here, we investigated the concomitant effects of AVP on the paracellular properties of mTAL. Freshly isolated mouse mTALs were perfused and electrophysiological transcellular and paracelluar properties were assessed in a paired fashion before and after AVP stimulation. In addition, the same parameters were measured in mice on a water-restricted (WR) or water-loaded (WL) diet for 5 days. Acute ex vivo stimulation as well as long-term in vivo water restriction increased equivalent short circuit current as a measure of active transcellular NaCl transport. Intriguingly, in both experimental approaches, this was accompanied by markedly increased paracellular Na selectivity. Thus, AVP is able to acutely regulate paracellular cation selectivity in parallel to transcellular NaCl transport, allowing balanced paracellular Na absorption under an increased transepithelial driving force.

Background

Purpose New lasers with a continuous wave power exceeding 15 W are currently investigated for retinal therapies, promising highly localized effects at and close to the Retinal Pigment Epithelium (RPE). The goal of this work is to evaluate mechanisms and thresholds for RPE cell damage by means of pulse durations up to 50 µs. Methods A diode laser with a wavelength of 514 nm, a power of 15 W, and adjustable pulse durations between 2 µs and 50 µs was used. Porcine RPE-choroidal explants (ex vivo) and chinchilla bastard rabbits (in vivo) were irradiated to determine threshold radiant exposures for RPE damage by calcein vitality staining and fluorescence angiography, respectively. Thresholds for microbubble formation (MBF) were evaluated by time-resolved optoacoustics. Exemplary histologies support the findings. Results is significantly higher than at pulse durations ≥ 5 µs ( P < 0.05) ex vivo, while at 2 µs, no statistically significant difference was found. The ratios between and increase with pulse duration from 1.07 to 1.48 ex vivo and 1.1 to 1.6 in vivo, for 5.2 and 50 µs. Conclusions Cellular damage with and without MBF related disintegration are both present and very likely to play a role for pulse durations ≥ 5 µs. With the lower µs pulses, selective RPE disruption might be possible, while higher values allow achieving spatially limited thermal effects without MBF. However, both modi require a very accurate real-time dosing control in order to avoid extended retinal disintegration in this power range.

The inner medullary collecting duct (IMCD) is subject to severe changes in ambient osmolality and must either allow water transport or be able to seal the lumen against a very high osmotic pressure. We postulate that the tight junction protein claudin-19 is expressed in IMCD and that it takes part in epithelial adaptation to changing osmolality at different functional states. Presence of claudin-19 in rat IMCD was investigated by Western blotting and immunofluorescence. Primary cell culture of rat IMCD cells on permeable filter supports was performed under different osmotic culture conditions and after stimulation by antidiuretic hormone (AVP). Electrogenic transepithelial transport properties were measured in Ussing chambers. IMCD cells cultivated at 300 mosm/kg showed high transepithelial resistance, a cation selective paracellular pathway and claudin-19 was mainly located in the tight junction. Treatment by AVP increased cation selectivity but did not alter transepithelial resistance or claudin-19 subcellular localization. In contrast, IMCD cells cultivated at 900 mosm/kg had low transepithelial resistance, anion selectivity, and claudin-19 was relocated from the tight junctions to intracellular vesicles. The data shows osmolality-dependent transformation of IMCD epithelium from tight and sodium-transporting to leaky, with claudin-19 expression in the tight junction associated to tightness and cation selectivity under low osmolality.

The nephron segments in the inner medulla are part of the urine concentrating mechanism. Depending on the diuretic state, they are facing a large range of extracellular osmolality. We investigated whether water homeostasis affects tubular transport and permeability properties in inner medullary descending thin limb (IMdTL) and ascending thin limb (IMaTL). Three experimental groups of rats under different diuretic states were investigated on metabolic cages: waterload, furosemide-induced diuresis, and control (antidiuresis). Urine production and osmolalities reflected the 3-day treatment. To functionally investigate tubular epithelial properties, we performed experiments in freshly isolated inner medullary thin limbs from these animals. Tubular segments were acutely dissected and investigated for trans- and paracellular properties by in vitro perfusion and electrophysiological analysis. IMdTL and IMaTL were distinguished by morphological criteria. We confirmed absence of transepithelial electrogenic transport in thin limbs. Although diffusion potential measurements showed no differences between treatments in IMdTLs, we observed increased paracellular cation selectivity under waterload in IMaTLs. NaCl diffusion potential was -5.64 ± 1.93 mV under waterload, -1.99 ± 1.72 mV under furosemide-induced diuresis, and 0.27 ± 0.40 mV under control. The corresponding permeability ratio P was 1.53 ± 0.21 (waterload), 1.22 ± 0.18 (furosemide-induced diuresis), and 0.99 ± 0.02 (control), respectively. Claudins are main constituents of the tight junction responsible for paracellular selectivity; however, immunofluorescence did not show qualitative differences in claudin 4, 10, and 16 localization. Our results show that IMaTLs change tight junction properties in response to diuretic state to allow adaptation of NaCl reabsorption.

Background: Central serous chorioretinopathy (CSC) is a common macular condition characterized by detachment of the neuroretina and is a frequent cause of central vision loss in adults. Among the various therapeutic strategies, subthreshold microsecond pulsed laser (SML) treatment has become a useful option. Despite the suggested involvement of choroidal circulatory disturbances in CSC, the effects of this treatment on macular microperfusion have not been fully evaluated yet. Herein, we report the impact of SML on retinal and choroidal microvascular flow using non-invasive optical coherence tomography (OCT) angiography (OCTA). Methods: In this study, CSC patients with persistent subretinal fluid (SRF) with or without secondary choroidal neovascularization (CNV) were included (referred to as the pachychoroid neovasculopathy (PNV) group and the CSC group, respectively). SML was conducted using a yellow (577 nm) laser with a duty cycle of 10%, spot size of 200 µm and duration of 200 ms. Best corrected visual acuity (BCVA) as well as OCT and OCTA images were evaluated at baseline and 4 weeks after SML. OCTA parameters of interest included full retinal perfusion (FRP), choriocapillaris perfusion (CCP), Sattler’s layer perfusion (SLP), and Haller’s layer perfusion (HLP), which were evaluated longitudinally and compared to unaffected fellow eyes. Results: 27 affected eyes and 17 fellow eyes from 27 patients were included. Before treatment, central retinal thickness (CRT) and subfoveal choroidal thickness (SFCT) of affected eyes were significantly larger than in fellow eyes. Four weeks after SML, CRT decreased significantly, whereas perfusion parameters did not change. In subgroup analyses, the CSC group showed a significant decrease in SFCT, whereas the PNV group did not despite the decrease in CRT. Conclusion: Our results suggest that the SML may affect the SFCT of the CSC, but not the PNV patients at least within four weeks following treatment. This effect seems to be independent of the change in choroidal perfusion measured with OCTA.

Glaucoma filtering surgery is applied to reduce intraocular pressure (IOP) in cases of uncontrolled glaucoma. However, postoperative fibrosis reduces the long-term success of both standard trabeculectomy and microstents. The aim of this study was to test the antiproliferative and anti-inflammatory potential of ZnO-tetrapods (ZnO-T) on human Tenon’s fibroblasts (HTFs) for glaucoma surgery. The toxicity of ZnO-T on HTFs was determined using an MTT test. For analysis of fibroblast proliferation, migration, and transdifferentiation, cultures were stained for Ki67, alpha-smooth muscle actin (α-SMA), and p-SMAD. A fully quantitative multiplex ELISA was used to determine the concentrations of different cytokines, platelet-derived growth factor (PDGF), and hepatocyte growth factor (HGF) in culture supernatants with and without previous ZnO-T treatment. Treatment with higher concentrations (10 and 20 µg/mL) was associated with HTF toxicity, as shown in the wound healing assay. Furthermore, the number of Ki67, α-SMA-positive, and pSMAD-positive cells, as well as IL-6 and HGF in supernatants, were significantly reduced following incubation with ZnO-T. In conclusion, we were able to show the antiproliferative and anti-inflammatory potentials of ZnO-T. Therefore, the use of ZnO-T may provide a new approach to reducing postoperative fibrosis in glaucoma filtering surgery.