Potassium Concentrations in Transgender Women Using Spironolactone: A Retrospective Chart Review

ObjectiveTo assess the incidence of hyperkalemia in transgender women using spironolactone.MethodsThis was a retrospective chart review of transgender women who received gender-affirming hormone therapy that included spironolactone between January 2000 and September 2018. Forty-four participants who had paired potassium concentrations documented and were on spironolactone were included and analyzed. Study outcomes included the incidence of hyperkalemia (serum potassium concentrations > 5.0 mmol/L), the relationship between the duration of treatment and degree of hyperkalemia, and difference between serum potassium concentrations at the beginning of spironolactone treatment versus last serum potassium concentrations.ResultsThe median age of the participants was 36.5 years. The cohort was predominantly non-Hispanic White (32/44). No serum potassium concentration was >5.5 mmol/L, and all participants had serum creatinine level of <2 mg/dL. Median duration of treatment was 25 months (range 2-92 months) and 140 potassium measurements were available. The mean potassium concentration (3.87 mmol/L) before the initiation of spironolactone was lower than the mean potassium concentration (4.03 mmol/L) while on spironolactone (mean difference, 0.16 mmol/L, P = .013). The regression β, that is, the average change in potassium concentration per 1 additional month of treatment duration, was ?.001 (95% CI [?.004, .001]; P = .255) signifying no relation between treatment duration and spironolactone use.ConclusionNo participant had laboratory evidence of significant hyperkalemia (K > 5.5 mmol/L) after initiation of spironolactone. Frequent measurement of potassium concentrations might be unnecessary in transgender women taking spironolactone in patients with serum creatinine levels of <2 mg/dL.     

The effect of reduced water potential on soybean mitochondria

The respiration of excised hypocotyls and of isolated hypocotyl mitochondria from soybean [Glycine max (L.) Merr., var. Wayne] was determined in various concentrations of sucrose and potassium chloride. Hypocotyl oxygen uptake declined with increasing solute concentration; no specific effects of either solute were apparent. Mitochondrial state III respiration was strongly inhibited as the solute concentrations were raised and there was in addition a specific inhibitory effect of the salt. State IV respiration, however, was unaffected by the presence of osmoticum. ADP/O ratios were also unaffected, except at high potassium chloride concentrations (470 mm). The primary effect of solutes was thus to limit the rate of substrate oxidation.     

The Role of Storage Lipids in the Relation between Fecundity,Locomotor Activity,and Lifespan of Drosophila melanogaster Longevity-Selected and Control Lines

The contribution of insect fat body to multiple processes, such as development, metamorphosis, activity, and reproduction results in trade-offs between life history traits. In the present study, age-induced modulation of storage lipid composition in Drosophila melanogaster longevity-selected (L) and non-selected control (C) lines was studied and the correlation between total body fat mass and lifespan assessed. The trade-offs between fecundity, locomotor activity, and lifespan were re-evaluated from a lipid-related metabolic perspective. Fewer storage lipids in the L lines compared to the C lines supports the impact of body fat mass on extended lifespan. The higher rate of fecundity and locomotor activity in the L lines may increase the lipid metabolism and enhance the lipolysis of storage lipids, reducing fat reserves. The correlation between neutral lipid fatty acids and fecundity, as well as locomotor activity, varied across age groups and between the L and C lines. The fatty acids that correlated with egg production were different from the fatty acids that correlated with locomotor activity. The present study suggests that fecundity and locomotor activity may positively affect the lifespan of D. melanogaster through the inhibition of fat accumulation.     

Ionic and osmotic regulation of the haemolymph of the dragonfly, Libellula quadrimaculata (Odonata : Libellulidae)

Larvae of the widespread dragonfly, Libellula quadrimaculata, were adapted to a series of salt solutions, and the osmotic pressure, and sodium, potassium and chloride concentrations in the haemolymph measured. The regulation of potassium is extremely efficient over the range 0–50 m-mole/l. external concentration. Above this, larvae die. Sodium and chloride are regulated to a lesser extent, the larvae being able to withstand considerable changes in the concentration of these ions in the haemolymph. However, at higher external concentrations, the haemolymph concentration of these ions is maintained below that of the external medium. The osmotic pressure is regulated in parallel with sodium concentration over most of the range tested. However, in higher salinities, the osmotic pressure of the haemolymph does not fall below that of the external medium. This is seen as a strategy to limit the amount of drinking in saline media. Overall, the osmoregulatory system of L. quadrimaculata resembles that of brackish-water insects, rather than that of the more strictly freshwater dragonflies that have been studied.     

酿酒酵母X330高浓度发酵时耐酒精性能的初步研究

在完全合成培养基条件下,就渗透压保护剂和营养物质对一株产高浓度酒精的酿酒酵母X330高浓度发酵时耐酒精性能的影响进行了初步研究。结果表明,与渗透压相比,营养缺乏对酿酒酵母高浓度发酵时酒精耐受性能可能起着更为关键和重要的作用。发酵培养基中各营养元素对耐酒精性能的影响不同,由高到低的顺序是酵母抽提物>蛋白胨>硫酸镁>维生素C=磷酸二氢钾>氯化钙=硫酸铵。渗透压保护剂(甘氨酸和脯氨酸)能有效提高菌体酒精耐受性能。当甘氨酸添加浓度为20mmol/L或脯氨酸添加浓度为10mmol/L时,发酵终点酒精浓度最高,菌体于30℃在18%(V/V)酒精冲击下的存活率最大,且均高于对照组(未添加甘氨酸且未添加脯氨酸)水平,但甘氨酸的促进作用强于脯氨酸。     

Activation of AMPK by the Putative Dietary Restriction Mimetic Metformin Is Insufficient to Extend Lifespan in Drosophila

The biguanide drug, metformin, commonly used to treat type-2 diabetes, has been shown to extend lifespan and reduce fecundity in C. elegans through a dietary restriction-like mechanism via the AMP-activated protein kinase (AMPK) and the AMPK-activating kinase, LKB1. We have investigated whether the longevity-promoting effects of metformin are evolutionarily conserved using the fruit fly, Drosophila melanogaster. We show here that while feeding metformin to adult Drosophila resulted in a robust activation of AMPK and reduced lipid stores, it did not increase lifespan in either male or female flies. In fact, we found that when administered at high concentrations, metformin is toxic to flies. Furthermore, no decreases in female fecundity were observed except at the most toxic dose. Analysis of intestinal physiology after metformin treatment suggests that these deleterious effects may result from disruptions to intestinal fluid homeostasis. Thus, metformin appears to have evolutionarily conserved effects on metabolism but not on fecundity or lifespan.     

Caenorhabditis elegans battling starvation stress: low levels of ethanol prolong lifespan in L1 larvae

The nematode Caenorhabditis elegans arrests development at the first larval stage if food is not present upon hatching. Larvae in this stage provide an excellent model for studying stress responses during development. We found that supplementing starved larvae with ethanol markedly extends their lifespan within this L1 diapause. The effects of ethanol-induced lifespan extension can be observed when the ethanol is added to the medium at any time between 0 and 10 days after hatching. The lowest ethanol concentration that extended lifespan was 1 mM (0.005%); higher concentrations to 68 mM (0.4%) did not result in increased survival. In spite of their extended survival, larvae did not progress to the L2 stage. Supplementing starved cultures with n-propanol and n-butanol also extended lifespan, but methanol and isopropanol had no measurable effect. Mass spectrometry analysis of nematode fatty acids and amino acids revealed that L1 larvae can incorporate atoms from ethanol into both types of molecules. Based on these data, we suggest that ethanol supplementation may extend the lifespan of L1 larvae by either serving as a carbon and energy source and/or by inducing a stress response.     

Relative Ion Permeabilities in the Crayfish Giant Axon Determined from Rapid External Ion Changes

The changes in membrane potential of isolated, single crayfish giant axons following rapid shifts in external ion concentrations have been studied. At normal resting potential the immediate change in membrane potential after a variation in external potassium concentration is quite marked compared to the effect of an equivalent chloride change. If the membrane is depolarized by a maintained potassium elevation, the immediate potential change due to a chloride variation becomes comparable to that of an equivalent potassium change. There is no appreciable effect on membrane potential when external sodium is varied, at normal or at a depolarized membrane potential. Starting from the constant field equation, expressions for the permeability ratios P _Cl/P _K, P _Na/P _K, and for intracellular potassium and chloride concentrations are derived. At normal resting membrane potential, P _Cl/P _K is 0.13 but at a membrane potential of -53 mv (external potassium level increased about five times) it is 0.85. The intracellular concentrations of potassium and chloride are estimated to be 233 and 34 mM, respectively, and it is pointed out that this is not compatible with ions distributed in a Nernst equilibrium across the membrane. It is also stressed that the information given by a plot of membrane potential vs. the logarithm of external potassium concentrations is very limited and rests upon several important assumptions.     

The effect of potassium sorbate, NaCl and pH on the growth of food spoilage fungi

In this study, the hurdle technology approach was used to prevent fungal growth of common spoilage fungi in naturally fermented black olives (Alternaria alternata, Aspergillus niger, Fusarium semitectum andPenicillium roqueforti). The factors studied included a combination of different concentrations of potassium sorbate (100 up to 1000 mg/L), a range of pH values (4.5, 5, 5.5, 6, and 6.5) and levels of NaCl (0, 3.5, 5, 7.5, and 10%).Alternaria alternata was the most sensitive fungus whereasP. roqueforti was the most resistant fungi against all hurdle factors. The combination of all hurdles completely inhibitedA. alternata andF. semitectum by lowest inhibitory factors, such as 100 mg/L potassium sorbate with 3.5% NaCl at pH 5. On the other hand, at pH 5, A.niger andP. roqueforti were totally prevented by a combination of 300 mg/L potassium sorbate with 10% NaCl and 400 mg/L potassium sorbate with 7.5% NaCl, respectively. Potassium sorbate and 5–10% NaCl interaction had significant stimulation effect onp. roqueforti andA. niger (p<0.05). This study indicates that potassium sorbate is a suitable preserving agent to inhibit growth of fungi in fermented products of pH near 4.5 regardless levels of NaCl. For products of slightly higher pH, the addition of potassium sorbate is suggested in combination with NaCl.     

寄主钾营养对烟粉虱发育、存活和寄主选择的影响

为了探讨寄主钾营养对烟粉虱发育、存活和寄主选择的影响,设置了K0（0 mg/L）、K30（30 mg/L）、K60（60 mg/L）、K120（120 mg/L）和K240（240 mg/L）5种不同钾浓度,研究了烟粉虱在不同处理黄瓜上的发育历期、存活率、体形以及成虫的寄主选择。结果表明：在温度（26±1）℃,相对湿度80%±5%的条件下,取食不同钾营养水平黄瓜的烟粉虱在发育历期、存活率、体形上均有差异,其中在K240处理黄瓜上烟粉虱若虫发育最慢,从卵到成虫的时间最长,为21.4天,而在K60处理黄瓜上最快,为18.3天。在不同钾浓度处理寄主上从卵到成虫存活率以K30处理黄瓜上最高（84.7%）,其次依次为K60（83.8%）、K120（76.2%）、K0（71.4%）和K240（64.8%）。在体形上以K30处理黄瓜上最大,K240处理黄瓜上最小。寄主选择性试验结果表明,在温室条件下,烟粉虱成虫喜欢在K60处理黄瓜上取食和产卵。这些结果提示在一定范围内可以通过调节寄主钾营养状况来调控烟粉虱种群。     

Effects of rice potassium level on the fecundity and expression of the vitellogenin gene of Nilaparvata lugens (Stål) (Hemiptera: Delphacidae)

Potassium (K) is a key component of plant nutrition, significantly influencing crop growth. Levels of this nutrient in plants can also influence a number of pest infestations. The brown planthopper, Nilaparvata lugens (Stål) (Hemiptera: Delphacidae), is an important pest of rice in Asia. In this study, we examined K contents in rice grown in hydroponic solution, and its relationship to the fecundity and expression of the vitellogenin (Nlvg) gene of N. lugens which was reared on the rice. Our findings indicated that K contents in rice increased with the increasing K concentration within the hydroponic solution, but reduced at the highest K concentration (160 mg/L). The number of eggs laid by N. lugens which was reared on the rice varied significantly with K concentration, and increased by 0.12 and 0.22 fold under 20 mg/L and 160 mg/L K level compared to that of the control (40 mg/L), decreasing by 0.57 fold under 0 mg/L K. Nlvg mRNA expression increased 1.17 and 1.94 fold in individuals which were reared on rice grown in 20 mg/L and 160 mg/L K level, compared to that of the control before mating; and by 3.36 and 2.97 after mating, respectively. However, Nlvg mRNA expression fold decreased by 0.99 under 0 mg/L K level before mating and 0.91 after mating. The variation of eggs may be attributed to the change of Nlvg mRNA expression, because there was a positive correlation between the eggs and Nlvg mRNA expression. These results demonstrated low (20 mg/L) and highest K levels (160 mg/L) in hydroponic solution showed the lower K level in plants than the control, which facilitated the fecundity of N. lugens. The study of the effects of K levels on the fecundity should have significance for insect control.     

Fluid secretion by isolated Malpighian tubules of the housefly Musca domestica

The Malpighian tubules of Musca domestica secrete a fluid with a high concentration of potassium and low concentrations of sodium, calcium, magnesium and chloride compared with the isolating medium.Low secretion rates are produced by low medium potassium concentrations (< 7 mM), with low sodium concentrations (up to 5 mM) increasing secretion; higher potassium concentrations produce higher secretion rates whilst higher sodium concentrations have no further effect. Calcium and magnesium are essential for secretion.The rate of tubule secretion is inversely proportional to the osmotic pressure of the isolating medium and the osmotic pressure of the secreted fluid is slightly hyper-osmotic to the medium over a range of medium osmotic pressures.The metabolic inhibitors cyanide, iodoacetate and 2,4-dinitrophenol inhibit secretion: Cu²⁺ ions, arsenate and ouabain have no effect whereas ethacrynic acid abolishes secretion. 5-hydroxytryptamine, cycle AMP and theophylline have no effect on secretion. Sodium thiocyanate stimulates fluid secretion and increases the osmotic pressure and the concentration of sodium and chloride, but not potassium, in the secreted fluid.     

Substrate regulation of single potassium and chloride ion channels in Arabidopsis plasma membrane

Patch clamp measurements of excised inside-out patches of Arabidopsis thaliana plasma membrane reveal at least two ion channels which conduct either potassium or chloride. The conductance of the potassium channel ranged from 5 to 70 picosiemens depending on KCl concentration. The conductance increased linearly with increasing cytoplasmic-side [KCl]; the extent of this dependence declined as extracytoplasmic-side [KCl] was increased. This indicates that substrate regulation of the potassium channel is a consequence of the molecular architecture of the channel: in particular, multi-ion binding sites within the channel pore. The chloride channel conductance (ranging from 5-40 picosiemens) was independent of cytoplasmic-side [KCl] until a threshold concentration of about 300 millimolar was reached. Such behavior is expected only if the channel is allosterically regulated by cytoplasmic-side K⁺ and/or Cl⁻. The median open times of either channel (about 200 milliseconds for the potassium channel and 20 milliseconds for the chloride channel) were unaffected by substrate concentrations.     

Acrylamide and Acrylic Acid Biodegradation by <Emphasis Type="Italic">Alcaligenes faecalis</Emphasis> 2 Planktonic Cells and Biofilms

The ability of the Alcaligenes faecalis 2 strain to utilize acrylamide and acrylic acid upon cultivation with these compounds as the only sources of carbon and energy has been investigated. Complete utilization of the acrylic acid present in the medium at concentrations below 0.113 g/L was observed by cultivation day 5, at a concentration of 0.225 g/L by day 7, and at a concentration of 0.45 g/L by day 17. Complete utilization of the acrylamide present in the medium at concentrations below 0.4 g/L was observed by day 5, at a concentration of 0.9 g/L by day 7, and at a concentration of 1.8 g/L by day 20. Importantly, bacterial growth did not start before complete transformation of acrylamide into acrylic acid. The rate of acrylamide transformation by growing bacteria and a cell suspension in the stationary growth phase amounted to 12.5 mg/L h at a cell concentration of 610 mg/L and 300 mg/L h, at a concentration of 1500 mg/L. A. faecalis 2 cells immobilized on BVV-22 basalt fibers and Carbopon-B-aktiv at concentrations of 3000 and 800 mg dry cells/L, respectively, transformed acrylamide at a rate of 1200 mg/L h.     

不同浓度吗啡对心肌动作电位的作用及其机制

用微电极技术研究不同浓度吗啡对豚鼠右心室乳头肌动作电位的作用及作用机制。低浓度吗啡(0.2—1.6 umol/L)使动作电位时程(APD)和有效不应期(ERP)缩短,呈剂量依赖性。此作用可被1μmol/L 纳洛酮、酚妥拉明,四乙胺和氯化铯阻断,但不能被异搏定阻断。高浓度吗啡(15—120μmol/L)则使 APD 和 ERP 延长,呈剂量依赖性,这作用不被1.2μmol/L纳洛酮阻断,但可被10μmol/L 纳洛酮、酚妥拉明、四乙胺、氯化铯和异搏定阻断。这些实验提示低浓度和高浓度的吗啡可能作用于不同的阿片受体亚型,低浓度吗啡的作用可能与钾通道有关,高浓度吗啡的作用可能与钾通道、钙通道或钙激活的钾通道有关。阿片受体的作用与α受体存在密切关系。     

Improvement of cloned alpha-amylase gene expression in fed-batch culture of recombinant Saccharomyces cerevisiae by regulating both glucose and ethanol concentrations using a fuzzy controller

The effect of ethanol concentration on cloned gene expression in recombinant Saccharomyces cerevisiae strain 20B-12 containing one of two plasmids, pNA3 and pNA7, was investigated in batch cultures. Plasmids pNA3 and pNA7 contain the alpha-amylase gene under the control of the SUC2 or PGK promoter, respectively. When the ethanol concentration was controlled at 2 to 5 g/L, the gene expressions were two times higher than those at 20 g/L ethanol. The increase the gene expression by maintaining both the ethanol and glucose concentrations at low levels, a fuzzy ontroller was developed. The concentrations of glucose and ethanol were controlled simultaneously at 0.15 and 2 g/L, respectively, in the production phase using the fuzzy controller in fed-batch culture. The synthesis of alpha-amylase was induced by the low glucose concentration and maintained at a high level of activity by regulating the ethanol concentration at 2 g/L. The secretory alpha-amylase was induced by the low glucose concentration and maintained at a high level of activity by regulating the ethanol concentration at 2 g/L. The secretory alpha-amylase activities of cells harboring plasmids pNA3 and pNA7 in fed-batch culture were 175 and 395 U/mL, and their maximal specific activities 7.7 and 12.4 U/mg dry cells, respectively. These values are two to three times higher in activity and three to four times higher in specific activity than those obtained when glucose only was controlled. (c) 1994 John Wiley & Sons, Inc.     

Inhibition of cellulases by phenols

Enzyme hydrolysis of pretreated cellulosic materials slows as the concentration of solid biomass material increases, even though the ratio of enzyme to cellulose is kept constant. This form of inhibition is distinct from substrate and product inhibition, and has been noted for lignocellulosic materials including wood, corn stover, switch grass, and corn wet cake at solids concentrations greater than 10 g/L. Identification of enzyme inhibitors and moderation of their effects is of considerable practical importance since favorable ethanol production economics require that at least 200 g/L of cellulosic substrates be used to enable monosaccharide concentrations of 100 g/L, which result in ethanol titers of 50 g/L. Below about 45 g/L ethanol, distillation becomes energy inefficient. This work confirms that the phenols: vanillin, syringaldehyde, trans-cinnamic acid, and hydroxybenzoic acid, inhibit cellulose hydrolysis in wet cake by endo- and exo-cellulases, and cellobiose hydrolysis by β-glucosidase. A ratio of 4 mg of vanillin to 1 mg protein (0.5 FPU) reduces the rate of cellulose hydrolysis by 50%. β-Glucosidases from Trichoderma reesei and Aspergillus niger are less susceptible to inhibition and require about 10× and 100× higher concentrations of phenols for the same levels of inhibition. Phenols introduced with pretreated cellulose must be removed to maximize enzyme activity.     

Effect of Ammonium Ions on Egg Hatching and Second-Stage Juveniles of Meloidogyne incognita in Axenic Tomato Root Culture

Eggs, either dispersed or in masses, and second-stage juveniles (J2) of Meloidogyne incognita were exposed to different concentrations of ammonium ions in a nutrient agar medium upon which excised tomato roots were growing. Egg hatch and J2 penetration of the roots was slowed or inhibited at high (54 and 324 mg/liter) but not at low (1.5 and 9 mg/liter) concentrations of ammonium nitrate. The effect of ammonium on J2 appeared to be temporary and reversible. High potassium nitrate concentration (1,116 mg/liter) did not modify egg hatch or J2 penetration. There was no adverse effect from the high ammonium nitrate concentrations or an equivalent potassium nitrate concentration on root dry weight. Ammonium ions influence nematodes both directly and via plant roots and do so independently of microbial organisms.     

Effect of calcium on the performance and morphology ofZymomonas mobilis ATCC 29191 in continuous ethanol fermentations

Summary The effect of calcium chloride, over a concentration range of 0–40mM (equivalent to 0–5.88g/L), on various steady-state parameters associated with the chemostat culture ofZ. mobilis ATCC 29191, in a defined salts medium containing 100g/L glucose, was examined. In contradiction of reports by other authors that calcium chloride (>2g/L) inhibits both the growth rate and ethanol yield while at the same time increasing the biomass yield, it was observed in the present study that 25mM (3.7g/L) CaCl₂ did not appreciably affect any of these fermentation parameters. The D_max (dilution rate for 95% substrate utilization) of 0.22/hr was not affected until the concentration of calcium chloride exceeded 30mM (4.41g/L). The apparent increase in biomass yield produced by calcium can be attributed to the formation of insoluble calcium carbonate. Calcium induced morphological changes of the biomass with filamentous growth were seen at concentrations >30 mM. Sparging with nitrogen gas reduces the dissolved carbon, dioxide, lessens the apparent inhibitory effect of calcium on the ethanol productivity and decreases the degree of filament formation.