Worsening effect of testosterone deficiency on males with heart failure with preserved ejection fraction.

BACKGROUND: Heart failure with preserved ejection fraction (HFpEF)is challenging. Patients usually have normal LV size and ejection fraction. This clinical syndrome develops from a complex interaction of several risk factors that cause organ dysfunction and clinical symptoms. There's evidence that testosterone deficiency is associated with a worse cardiometabolic profile and increased inflammatory markers. We thought that these changes might have an impact on heart failure pathogenesis. We aimed to study the relationship between testosterone level and symptoms in HFpEF. METHODS: We studied 120 male patients with HFpEF. According to New York Heart Association (NYHA), patients were classified into I, II and III classes; class IV patients were excluded. All patients were subjected to clinical and echocardiographic examinations. In addition, we measured serum testosterone, cardio-metabolic profile, intracellular adhesive molecule-1(ICAM-1), P-selectin and nitric oxide (NO) levels. RESULTS: Patients with testosterone deficiency had worse NYHA class and higher BNP P = (0.001). Additionally, they had a significantly worse metabolic profile; higher total cholesterol, triglycerides, LDL cholesterol, fasting insulin and HOMA-IR P = (0.005, 0.001, 0.001, 0.001), respectively. Also, they had higher inflammatory markers and worse endothelial functional parameters; (ICAM-1, NO and P- selectin) P = (0.001). Age, BNP and testosterone deficiency can be used as independent predictors of NYHA class III symptoms with a Testosterone cutoff value of 2.7 ng/ml. CONCLUSION: Testosterone deficiency could be used as an independent predictor of symptom severity in HFpEF, and it aggravates systemic inflammation and endothelial dysfunction in these patients.

The Safety of The Directly Acting Antiviral Treatment For Hepatitis C Virus According To The Egyptian National Program Protocol In Patients With Midrange Ejection Fraction.

Background: The Egyptian National Committee of Viral Hepatitis program is the leading national hepatitis C virus (HCV) management program globally. However, limited data is available about the effect of the new directly acting antiviral agents on the cardiovascular system. Objectives: Our study aimed to assess the safety of the relatively new directly acting antiviral agents approved by the National Health Committee in Egypt to treat patients infected with hepatitis C virus who have midrange left ventricular ejection fraction. Methods: This multicenter study included 400 successive patients with an ejection fraction (40-49%) from May 2017 to December 2019. We classified them into two groups: Group I (Child A), who received Sofosbuvir and Daclatasvir for twelve weeks, and Group II (Child B), who received Sofosbuvir, Daclatasvir, and Ribavirin for twelve weeks. Patients were evaluated for their symptoms, ejection fraction, brain natriuretic peptide, lipid profile, fasting blood glucose, fasting insulin, Homeostatic Model Assessment of Insulin Resistance levels, and Holter monitoring (just before the start of treatment and within three days after completing therapy). Results: We found New York Heart Association Class, ejection fraction, brain natriuretic peptide, premature ventricular contractions burden, as well as highest and lowest heart rate did not show a statistically significant difference in both groups after treatment. The treatment did not cause bradycardia or non-sustained ventricular tachycardia. Fasting blood glucose and fasting insulin levels declined, with improved insulin resistance after treatment in both groups. Both low and high-density lipoprotein cholesterol increased after treatment in Group II. Conclusions: Both regimens of directly acting antiviral agents used in Egypt to treat chronic hepatitis C virus infection are safe in patients with New York Heart Association Class I and II with midrange left ventricular ejection fraction (40-49%). There are beneficial metabolic changes following HCV clearance as an improvement of insulin resistance.

Plasma-membrane electrical responses to salt and osmotic gradients contradict radiotracer kinetics, and reveal Na+-transport dynamics in rice (Oryza sativa L.).

MAIN CONCLUSION: A systematic analysis of NaCl-dependent, plasma-membrane depolarization (∆∆Ψ) in rice roots calls into question the current leading model of rapid membrane cycling of Na+ under salt stress. To investigate the character and mechanisms of Na+ influx into roots, Na+-dependent changes in plasma-membrane electrical potentials (∆∆Ψ) were measured in root cells of intact rice (Oryza sativa L., cv. Pokkali) seedlings. As external sodium concentrations ([Na+]ext) were increased in a step gradient from 0 to 100 mM, membrane potentials depolarized in a saturable manner, fitting a Michaelis-Menten model and contradicting the linear (non-saturating) models developed from radiotracer studies. Clear differences in saturation patterns were found between plants grown under low- and high-nutrient (LN and HN) conditions, with LN plants showing greater depolarization and higher affinity for Na+ (i.e., higher Vmax and lower Km) than HN plants. In addition, counterion effects on ∆∆Ψ were pronounced in LN plants (with ∆∆Ψ decreasing in the order: Cl- > SO42- > HPO 4 2- ), but not seen in HN plants. When effects of osmotic strength, Cl- influx, K+ efflux, and H+-ATPase activity on ∆∆Ψ were accounted for, resultant Km and Vmax values suggested that a single, dominant Na+-transport mechanism was operating under each nutritional condition, with Km values of 1.2 and 16 mM for LN and HN plants, respectively. Comparing saturating patterns of depolarization to linear patterns of 24Na+ radiotracer influx leads to the conclusion that electrophysiological and tracer methods do not report the same phenomena and that the current model of rapid transmembrane sodium cycling may require revision.

Membrane fluxes, bypass flows, and sodium stress in rice: the influence of silicon.

Provision of silicon (Si) to roots of rice (Oryza sativa L.) can alleviate salt stress by blocking apoplastic, transpirational bypass flow of Na+ from root to shoot. However, little is known about how Si affects Na+ fluxes across cell membranes. Here, we measured radiotracer fluxes of 24Na+, plasma membrane depolarization, tissue ion accumulation, and transpirational bypass flow, to examine the influence of Si on Na+ transport patterns in hydroponically grown, salt-sensitive (cv. IR29) and salt-tolerant (cv. Pokkali) rice. Si increased growth and lowered [Na+] in shoots of both cultivars, with minor effects in roots; neither root nor shoot [K+] were affected. In IR29, Si lowered shoot [Na+] via a large reduction in bypass flow, while in Pokkali, where bypass flow was small and not affected by Si, this was achieved mainly via a growth dilution of shoot Na+. Si had no effect on unidirectional 24Na+ fluxes (influx and efflux), or on Na+-stimulated plasma-membrane depolarization, in either IR29 or Pokkali. We conclude that, while Si can reduce Na+ translocation via bypass flow in some (but not all) rice cultivars, it does not affect unidirectional Na+ transport or Na+ cycling in roots, either across root cell membranes or within the bulk root apoplast.

Measurement of Differential Na(+) Efflux from Apical and Bulk Root Zones of Intact Barley and Arabidopsis Plants.

Rapid sodium cycling across the plasma membrane of root cells is widely thought to be associated with Na(+) toxicity in plants. However, the efflux component of this cycling is not well understood. Efflux of Na(+) from root cells is believed to be mediated by Salt Overly-Sensitive-1, although expression of this Na(+)/H(+) antiporter has been localized to the vascular tissue and root meristem. Here, we used a chambered cuvette system in which the distal root of intact salinized barley and Arabidopsis thaliana plants (wild-type and sos1) were isolated from the bulk of the root by a silicone-acrylic barrier, so that we could compare patterns of (24)Na(+) efflux in these two regions of root. In barley, steady-state release of (24)Na(+) was about four times higher from the distal root than from the bulk roots. In the distal root, (24)Na(+) release was pronouncedly decreased by elevated pH (9.2), while the bulk-root release was not significantly affected. In A. thaliana, tracer efflux was about three times higher from the wild-type distal root than from the wild-type bulk root and also three to four times higher than both distal- and bulk-root fluxes of Atsos1 mutants. Elevated pH also greatly reduced the efflux from wild-type roots. These findings support a significant role of SOS1-mediated Na(+) efflux in the distal root, but not in the bulk root.

Measuring fluxes of mineral nutrients and toxicants in plants with radioactive tracers.

Unidirectional influx and efflux of nutrients and toxicants, and their resultant net fluxes, are central to the nutrition and toxicology of plants. Radioisotope tracing is a major technique used to measure such fluxes, both within plants, and between plants and their environments. Flux data obtained with radiotracer protocols can help elucidate the capacity, mechanism, regulation, and energetics of transport systems for specific mineral nutrients or toxicants, and can provide insight into compartmentation and turnover rates of subcellular mineral and metabolite pools. Here, we describe two major radioisotope protocols used in plant biology: direct influx (DI) and compartmental analysis by tracer efflux (CATE). We focus on flux measurement of potassium (K(+)) as a nutrient, and ammonia/ammonium (NH3/NH4(+)) as a toxicant, in intact seedlings of the model species barley (Hordeum vulgare L.). These protocols can be readily adapted to other experimental systems (e.g., different species, excised plant material, and other nutrients/toxicants). Advantages and limitations of these protocols are discussed.

Electrical phenotypes of calcium transport mutant strains of a filamentous fungus, Neurospora crassa.

We characterized the electrical phenotypes of mutants with mutations in genes encoding calcium transporters-a mechanosensitive channel homolog (MscS), a Ca(2+)/H(+) exchange protein (cax), and Ca(2+)-ATPases (nca-1, nca-2, nca-3)-as well as those of double mutants (the nca-2 cax, nca-2 nca-3, and nca-3 cax mutants). The electrical characterization used dual impalements to obtain cable-corrected current-voltage measurements. Only two types of mutants (the MscS mutant; the nca-2 mutant and nca-2-containing double mutants) exhibited lower resting potentials. For the nca-2 mutant, on the basis of unchanged conductance and cyanide-induced depolarization of the potential, the cause is attenuated H(+)-ATPase activity. The growth of the nca-2 mutant-containing strains was inhibited by elevated extracellular Ca(2+) levels, indicative of lesions in Ca(2+) homeostasis. However, the net Ca(2+) effluxes of the nca-2 mutant, measured noninvasively with a self-referencing Ca(2+)-selective microelectrode, were similar to those of the wild type. All of the mutants exhibited osmosensitivity similar to that of the wild type (the turgor of the nca-2 mutant was also similar to that of the wild type), suggesting that Ca(2+) signaling does not play a role in osmoregulation. The hyphal tip morphology and tip-localized mitochondria of the nca-2 mutant were similar to those of the wild type, even when the external [Ca(2+)] was elevated. Thus, although Ca(2+) homeostasis is perturbed in the nca-2 mutant (B. J. Bowman et al., Eukaryot. Cell 10:654-661, 2011), the phenotype does not extend to tip growth or to osmoregulation but is revealed by lower H(+)-ATPase activity.

Mid1, a mechanosensitive calcium ion channel, affects growth, development, and ascospore discharge in the filamentous fungus Gibberella zeae.

The role of Mid1, a stretch-activated ion channel capable of being permeated by calcium, in ascospore development and forcible discharge from asci was examined in the pathogenic fungus Gibberella zeae (anamorph Fusarium graminearum). The Δmid1 mutants exhibited a >12-fold reduction in ascospore discharge activity and produced predominately abnormal two-celled ascospores with constricted and fragile septae. The vegetative growth rate of the mutants was ∼50% of the wild-type rate, and production of macroconidia was >10-fold lower than in the wild type. To better understand the role of calcium flux, Δmid1 Δcch1 double mutants were also examined, as Cch1, an L-type calcium ion channel, is associated with Mid1 in Saccharomyces cerevisiae. The phenotype of the Δmid1 Δcch1 double mutants was similar to but more severe than the phenotype of the Δmid1 mutants for all categories. Potential and current-voltage measurements were taken in the vegetative hyphae of the Δmid1 and Δcch1 mutants and the wild type, and the measurements for all three strains were remarkably similar, indicating that neither protein contributes significantly to the overall electrical properties of the plasma membrane. Pathogenicity of the Δmid1 and Δmid1Δcch1 mutants on the host (wheat) was not affected by the mutations. Exogenous calcium supplementation partially restored the ascospore discharge and vegetative growth defects for all mutants, but abnormal ascospores were still produced. These results extend the known roles of Mid1 to ascospore development and forcible discharge. However, Neurospora crassa Δmid1 mutants were also examined and did not exhibit defects in ascospore development or in ascospore discharge. In comparison to ion channels in other ascomycetes, Mid1 shows remarkable adaptability of roles, particularly with regard to niche-specific adaptation.

42K analysis of sodium-induced potassium efflux in barley: mechanism and relevance to salt tolerance.

*Stimulation of potassium (K(+)) efflux by sodium (Na(+)) has been the subject of much recent attention, and its mechanism has been attributed to the activities of specific classes of ion channels. *The short-lived radiotracer (42)K(+) was used to test this attribution, via unidirectional K(+)-flux analysis at the root plasma membrane of intact barley (Hordeum vulgare), in response to NaCl, KCl, NH(4)Cl and mannitol, and to channel inhibitors. *Unidirectional K(+) efflux was strongly stimulated by NaCl, and K(+) influx strongly suppressed. Both effects were ameliorated by elevated calcium (Ca(2+)). As well, K(+) efflux was strongly stimulated by KCl, NH(4)Cl and mannitol , and NaCl also stimulated (13)NH(4)(+) efflux. The Na(+)-stimulated K(+) efflux was insensitive to cesium (Cs(+)) and pH 4.2, weakly sensitive to the K(+)-channel blocker tetraethylammonium (TEA(+)) and quinine, and moderately sensitive to zinc (Zn(2+)) and lanthanum (La(3+)). *We conclude that the stimulated efflux is: specific neither to Na(+) as effector nor K(+) as target; composed of fluxes from both cytosol and vacuole; mediated neither by outwardly-rectifying K(+) channels nor nonselective cation channels; attributable, alternatively, to membrane disintegration brought about by ionic and osmotic components; of limited long-term significance, unlike the suppression of K(+) influx by Na(+), which is a greater threat to K(+) homeostasis under salt stress.