The effects of lactose on human erythrocytes

Human erythrocytes suspended in isotonic lactose solution lost potassium and continued to lose potassium even when resuspended in isotonic sodium chloride. The same phenomenon was observed when the cells were suspended in an isotonic solution of the sodium salt of glutamate, a nonpenetrating anion. The presence of 5 mEq per liter of sodium chloride in the lactose or sodium glutamate suspensions greatly reduced the initial potassium loss and the potassium loss when the cells were resuspended in sodium chloride solution. Salts of nonpenetrating anions were less or not effective in blocking lactose damage. The results indicate that absence of penetrating anions in the suspending media is the initiating condition of lactose damage. Chloride and consequently potassium are lost from the erythrocyte. Changes in cellular ionic pattern and/or changes in the cell membrane result in a nontransient damage manifested by continued potassium loss by lactose-treated cells resuspended in isotonic NaCl.     

Osmoregulation in Rhizobium meliloti: inhibition of growth by salts

A defined medium of low osmolarity was developed permitting growth of Rhizobium meliloti with generation times of approximately 2.8 h doubling^-1. The effects of sodium, potassium, magnesium, ammonium, chloride, sulfate, phosphate, bicarbonate and acetate ions on the growth rate of R. meliloti were determined. Sodium, potassium and ammonium ions had little effect on growth at concentrations of 100 mEq or less; magnesium ion inhibited growth severely at concentrations of 50 mEq (25 mM). Of the anions, chloride and sulfate appeared to have little effect while phosphate, bicarbonate, and acetate inhibited growth at concentrations of as little as 25 mEq. The addition of proline, glutamate, or betaine to cells growing in inhibitory concentrations of NaCl did not relieve the inhibition. When grown in the presence of inhibitory levels of NaCl, the intracellular concentration of glutamate but not of proline or gamma amino butyric acid increased 5-fold.     

Production of an extracellular alkaline metalloprotease from a newly isolated, moderately halophile, Salinivibrio sp. strain AF-2004

An extracellular protease was produced under stress conditions of high temperature and high salinity by a newly isolated moderate halophile, Salinivibrio sp. strain AF-2004 in a basal medium containing peptone, beef extract, glucose and NaCl. A modification of Kunitz method was used for protease assay. The isolate was capable of producing protease in the presence of sodium chloride, sodium sulfate, sodium nitrate, sodium nitrite, potassium chloride, sodium acetate and sodium citrate. The maximum protease was secreted in the presence of 7.5 to 10% (w/v) sodium sulfate or 3% (w/v) sodium acetate (4.6 U ml⁻¹). Various carbon sources including glucose, lactose, casein and peptone were capable of inducing enzyme production. The optimum pH, temperature and aeration for enzyme production were 9.0, 32 °C and 220 rpm, respectively. The enzyme production corresponded with growth and reached a maximum level during the mid-stationary phase. Maximum protease activity was exhibited in the medium containing 1% (w/v) NaCl at 60 °C, with 18% and 41% activity reductions at temperature 50 and 70 °C, respectively. The optimum pH for enzyme activity was 8.5, with 86% and 75% residual activities at pH 10 and 6, respectively. The activity of enzyme was inhibited by EDTA. These results suggest that the protease secreted by Salinivibrio sp. strain AF-2004 is industrially important from the perspectives of its activity at a broad pH ranges (5.0–10.0), its moderate thermoactivity in addition to its high tolerance to a wide range of salt concentration (0–10% NaCl).     

In situ demonstration of angiotensin-dependent and independent pathways for hyperaldosteronism during chronic extracellular fluid volume depletion.

In wild-type mice, 2-wk administration of losartan, an angiotensin (Ang) II type 1 (AT1) receptor antagonist, along with dietary sodium restriction, resulted in an elevation of plasma aldosterone greater than that seen with sodium restriction alone (2.75 +/- 0.35 vs. 1.38 +/- 0.16 ng/ml, P < 0.01). Plasma potassium increased in sodium-restricted, losartan-treated mice (6.0 +/- 0.2 mEq/liter), while potassium remained unchanged in mice with sodium restriction alone. To study the effect of Ang II on glomerulosa cells that may operate independently of plasma potassium in situ, we used chimeric mice made of cells with or without the intact AT1A gene (Agtr1a). When animals were fed a normal diet or chronically infused with Ang II, the aldosterone synthase mRNA was detectable only in Agtr1a+/+ but not Agtr1a-/- zona glomerulosa cells. After 2 wk of sodium restriction, plasma aldosterone increased (1.51 +/- 0.27 ng/ml) and potassium remained on average at 4.5 +/- 0.2 mEq/liter, with aldosterone synthase mRNA expressed intensively in Agtr1a+/+, but not detectable in Agtr1a-/- cells. Simultaneous sodium restriction and losartan treatment caused increases in plasma potassium (5.5 +/- 0.1 mEq/liter) and aldosterone (1.84 +/- 0.38 ng/ml), with both Agtr1a-/- and Agtr1a+/+ cells intensively expressing aldosterone synthase mRNA. Thus, aldosterone production is regulated by Ang II in the adrenal gland during chronic alterations in extracellular fluid volume when plasma potassium is maintained within the normal range. In the light of a previous observation that dietary potassium restriction superimposed on sodium restriction abolished secondary hyperaldosteronism in angiotensinogen null-mutant mice, the present findings demonstrate that when the renin-Ang system is compromised, plasma potassium acts as an effective alternative mechanism for the volume homeostasis through its capacity to induce hyperaldosteronism.     

Gastrointestinal Replacement Solution

The mean sodium concentration of 61 gastrointestinal aspirations in peritonitis was 103 mEq/l. (S.D. 16·66), of 16 aspirations in vagotomy 88 mEq/l. (S.D. 19·49), of 12 aspirations in perforated duodenal ulcer 81 mEq/l. (S.D. 19·49), and of 15 aspirations in intestinal obstruction 89 mEq/l. (S.D. 19·49). The mean potassium concentrations were 9, 9·9, 13, and 8·8 mEq/l. respectively, and the mean chloride concentrations 122, 131, 125, and 112 mEq/l. respectively. It is suggested that a gastrointestinal replacement solution should contain 100 mEq of sodium, 12 mEq of potassium, and 122 mEq of chloride per litre; 50 g. of dextrose or 100 g. of fructose may be added to provide energy.     

Potassium changes in trained subjects after potassium loading and during restriction of muscular activity and chronic hyperhydration

The objective of this investigation was to determine whether urinary and plasma potassium changes developed during prolonged hypokinesia (HK) (decreased number of km/d) in endurance-trained subjects could be minimized or reversed with a daily intake of fluid and salt supplementation (FSS). The studies were performed on 30 endurance-trained male volunteers aged 23–26 yr with an average peak oxygen uptake of 65 mL/kg min during 364 d of HK. All volunteers were on an average of 13.8 km/d prior to their exposure to HK. All volunteers were randomly divided into three groups: 10 volunteers were placed continuously under an average of 14.0 km/d (control subjects), 10 volunteers were subjected continuously to an average of 2.7 km/d (unsupplemented hypokinetic subjects), and 10 volunteers were submitted continuously to an average of 2.7 km/d, and consumed daily an additional amount of 0.1 g sodium chloride (NaCl)/kg body wt and 30 mL water/kg body wt (supplemented hypokinetic subjects). During the prehypokinetic period of 60 d and during the hypokinetic period of 364 d, potassium loading tests were performed with 1.5–1.7 mEq potassium chloride/kg body wt, and potassium, sodium, and chloride excretion in urine and potassium, sodium, and chloride in plasma were determined. In the unsupplemented hypokinetic volunteers, urinary excretion of electrolytes and concentrations of electrolytes in plasma increased significantly as compared to the control and supplemented hypokinetic groups of volunteers. It was concluded that daily intake of fluid and salt supplementation had a favorable effect on regulation of urinary and plasma potassium changes in trained subjects during prolonged HK.     

Heat-induced injury inListeria monocytogenes

Summary Heating ofListeria monocytogenes (Scott A strain) in potassium phosphate buffer (0.1 M, pH 7.2) at 52°C for 1 h led to injury, with the heat-injured cells failing to produce colonies on agar medium containing 5% NaCl. The detection of injury was based on the use of differential media: plating on tryptose phosphate broth+2% agar and 1% sodium pyruvate (TPBA+P) and on tryptose phosphate broth+2% agar and 5% NaCl (TPBA+S). Only non-injuredListeria formed colonies on TPBA+S whereas both heat-injured and non-injured cells formed colonies on TPBA+P. The bacterial count on TPBA+P minus that on TPBA+S represents the extent of heat injury. A large number of selective agars were tested and compared to TPBA+P for their ability to support repair and colony formation of heat-injuredL. monocytogenes. Media containing 0.025% phenylethanol, 0.0012–0.0025% acriflavin, 0.1–0.2% potassium tellurite, 0.001% polymyxin B sulfate, 5% NaCl or a combination of these ingredients were detrimental to the recovery of heat-injuredL. monocytogenes. Media currently in use forL. monocytogenes are not satisfactory for the recovery of injured cells.     

Sodium chloride, potassium chloride, and virulence in Listeria monocytogenes.

Virulence, as determined in a mouse model, and the virulence factor activities of catalase, superoxide dismutase, and listeriolysin O were examined in a parental strain (10403S) and in a nonhemolytic mutant strain (DP-L224) of Listeria monocytogenes. The cells were propagated in media containing various concentrations of sodium chloride or potassium chloride. Strains 10403S and DP-L224 exhibited significant increases in catalase activity and listeriolysin O activity when grown in medium containing either salt at 428 mM. The superoxide dismutase activities for both strains increased when they were grown in medium containing either salt. The superoxide dismutase activity was significantly increased only when cells were propagated in medium containing no salt compared with that when they were propagated in medium containing either salt at 1,112 mM. In addition, the listeriolysin O activity was highest for cells propagated in medium containing KCl at 428 mM, while the activity was significantly less for cells propagated in medium containing NaCl at an equal concentration. Virulence was examined in mouse livers and spleens after intravenous infection, and approximate 50% lethal doses were determined after intragastric and intraperitoneal infection. Each method of infection indicated that listeriolysin O is required for virulence, while growth in salt-containing medium or the production of higher levels of catalase, superoxide dismutase, and listeriolysin O do not appear to enhance the virulence of L. monocytogenes.     

SENSORY CHARACTERISTICS OF POTASSIUM LACTATE AND SODIUM CHLORIDE IN A MODEL SYSTEM

The objective of this study was to assess the sensory characteristics of potassium lactate (PL) in combination with salt (NaCl) in a model system at common usage levels for meat systems. Using a gelatin-based (3%) model system containing various concentrations of potassium lactate (0%, 1%, 2%, and 3%) and sodium chloride (0%, 0.5%, 1%, 1.5%, 2%, 2.5%, and 3%), a sensory panel (10) selected for salt sensitivity (0.08% threshold or less) scored the intensity of saltiness and bitterness of each treatment combination using a scale of 0 = none and 15 = intense. As salt concentration increased, saltiness increased and bitterness decreased; as PL increased, saltiness and bitterness increased. At 2% salt, the bitterness of PL was masked; however, salt concentrations below and above 2% were less effective in bitterness reduction.     

Some characteristics of twoRhizobium trifolii isolates differing in salt tolerance

Two isolates ofRhizobium trifolii differing in sodium chloride tolerance were isolated. One isolate could tolerate 0.9 and 0.5 mol NaCl/L, while the second tolerated 0.2 and 0.1 mol NaCl/L on solid agar and liquid media, respectively. The first isolate showed a higher capacity to accumulate sodium ions. The salinity-caused increase in free amino acids, proline and oxo acid pool was higher in the first isolate. The levels of ammonia-assimilating enzymes were maintained at a higher level in this isolate even at 0.5 mol NaCl/L.     

Ion secretion by salt glands of desert iguanas (Dipsosaurus dorsalis)

Unlike the NaCl-secreting salt glands of many birds and reptiles, the nasal salt glands of lizards can secrete potassium as well as sodium, with either chloride or bicarbonate as the accompanying anion. The factors responsible for initiating secretion by the gland and the rates of cation and anion secretion were studied in the desert iguana, Dipsosaurus dorsalis. Lizards were given combinations of ions for several days, and secreted salt was collected daily and analyzed for sodium, potassium, chloride, and bicarbonate. Maximum total cation secretion rate was 4.4+/-0.38 micromol/g/d. Cation secretion ranged from 24% to 100% potassium; even high NaCl loads did not abolish potassium secretion. Maximum bicarbonate secretion was about 0.5 micromol/g/d; chloride was the predominant anion. Secretion rate increased only in response to those treatments that included potassium and/or chloride; sodium ions and other osmotic loads (e.g., sucrose) did not increase secretion. This is in contrast to birds and some other reptiles with salt glands, which initiate NaCl secretion in response to any osmotic load. The specificity of the response of the salt gland of Dipsosaurus may be related to the ecological importance of dietary potassium and chloride for herbivorous desert lizards.     

Calcium specificity of the antigen-induced channels in rat basophilic leukemia cells

Ion channels, activated upon IgE-Fc epsilon receptor aggregation by specific antigen, were studied in micropipet-supported lipid bilayers. These bilayers were reconstituted with purified IgE-Fc epsilon receptor complex and the intact 110-kDa channel-forming protein, both isolated from plasma membranes of rat basophilic leukemia cells (line RBL-2H3). In order to identify the current carrier through these ion channels and to determine their ion selectivity, we investigated the currents flowing through the IgE-Fc epsilon receptor gated channels in the presence of a gradient of Ca2+ ions. Thus, the solution in which the micropipet-supported bilayer was immersed contained 1.8 mM CaCl2, while the interior of the micropipet contained 0.1 microM Ca2+ (buffered with EGTA). Both solutions also contained 150 mM of a monovalent cation chloride salt (either K+ or Na+). The currents induced upon specific aggregation of the IgE (by either antigen or anti-IgE antibodies) were examined over a range of potentials imposed on the bilayer. The type of conductance event most frequently observed under the employed experimental conditions was a channel that has a slope conductance of 3 pS and a reversal potential practically identical with the calculated value for the reversal potential of calcium (134 +/- 11 mV in the presence of sodium, 125 +/- 13 mV in the presence of potassium). These results indicate that this channel is highly selective for calcium against the monovalent cations sodium and potassium. This same channel has a conductance of 4-5 pS in the presence of symmetrical solutions containing only 100 mM CaCl2 and 8 pS in the presence of 0.5 M NaCl with no calcium.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of moderate salinity on patterns of potassium, sodium and chloride accumulation in cells near the root tip of barley: Role of differentiating metaxylem vessels

X-Ray microanalysis of fully hydrated, bulk-frozen samples was used to measure concentrations of potassium, sodium and chloride in various cell types along seminal roots of barley ( Hordeum vulgare L. cv. California Mariout) seedlings (1 to 150 mm from the tip). In the cytoplasm of all meristematic cells 1 mm from the root tip, the average concentrations of potassium and chloride were ca 200 and 15 m M , respectively. The potassium level was also high in the vacuoles of incipient xylem elements and did not drop to significantly lower values until 10 mm from the tip in protoxylem, 50 mm in early metaxylem and 150 mm in late metaxylem (LMX). Light microscopy observations (Nomarski optics) of hand-cut sections showed the presence of cytoplasmic strands and also the presence of intact cross walls in LMX up to a distance of 100 mm. Both quantitative analysis of ion contents and structural observations suggested that LMX elements act as a large transitional sink of accumulated ions and therefore may not function as a main pathway of transport until perforation of the end wall takes place 100–150 mm from the root tip. Treatment with 50 m M NaCl resulted in higher concentrations of sodium and chloride in LMX elements than in the surrounding cells, suggesting that living xylem elements, which develop a large central vacuole at an early stage of root differentiation, may assist in alleviating salinity stress in the meristematic region of barley root tips. Further, it is proposed that reabsorption of sodium and chloride from the LMX, especially before the disappearance of the cross walls, may provide a means of salinity tolerance.     

Effect of lithium and rubidium on the ganglionic inhibitory action of norepinephrine

Close intraarterial infusion of lithium chloride (2 and 4 mEq/kg) transiently suppressed evoked postganglionic potentials in the superior cervical ganglion of the cat; lower doses (0.5 and 1 mEq/kg) had no effect on transmission. Potentiation of the ganglionic inhibitory effect of norepinephrine (NE) occurred at plasma concentrations of lithium equivalent to those found to be therapeutic in man. Concurrent administration of lithium (1 mEq/kg) and doxepin (25 mcg/kg) produced greater facilitation of the ganglionic suppressant effect of NE than either lithium or doxepin alone. Rubidium chloride (0.1, 0.5 and 1 mEq/kg) produced temporary blockade of ganglionic transmission; lower doses (0.05 and 0.075 mEq/kg) did not exhibit a ganglioplegic effect. Reduction of the ganglionic inhibitory activity of NE was observed at each dose level of rubidium. Administration of doxepin (25 mcg/kg) immediately after rubidium (0.075 mEq/kg) significantly reduced the inhibitory effect of the cation on NE activity. These results suggest that, in the cat superior cervical ganglion, lithium may block NE uptake and rubidium may promote NE release.     

添加剂对苏云金杆菌制剂杀虫效果的影响

供试13种化学物质中,12种物质对Bt制剂的杀虫效果有增效作用,各物质的不同质量浓度对杀虫效果影响差异显,在1g/L的剂量以下,多数添加剂的增效作用,随剂量的增加而增强,添加0．5g/L巯基乙醇增效作用最佳,增效倍数达3．61倍,0．5g/L的甲酸和尿素,及0．1g/L碳酸钾具有较好的增效作用,增效倍数分别为2．52,2．32和2．56和2．56倍,0．5g/L的马来酸,氯化钙,乙二胺四乙酸,氯化镁,硼酸,碳酸钠和1g/L的柠檬酸,磷酸氢二钾8种添加剂的增效倍数为0．53－1．88倍。     

Insulin,Glucose, and Potassium in the Treatment of Congestive Heart Failure

A daily infusion of 500-1,000 ml of 50% glucose containing 100-120 units of soluble insulin and 100-120 mEq of potassium chloride per litre was given to six patients suffering from hyponatraemia and congestive cardiac failure resistant to digoxin and diuretic therapy. In two patients there was no response, but four showed a striking improvement with a sodium and water diuresis, a rise in plasma sodium level, and in two cases a reversion from atrial fibrillation to sinus rhythm. It is suggested that insulin, glucose, and potassium given by the intravenous route in adequate dosage forms a useful adjunct to the management of severe congestive heart failure.     

Alkalotolerance of Yersinia enterocolitica as a basis for selective isolation from food enrichments.

Alkalotolerance of Yersinia enterocolitica measured in solutions of potassium hydroxide with 0.5% sodium chloride was influenced by the cell suspension medium, temperature, and growth phase. The rate of cell destruction (delta log N per minute) was five times greater at 30 degrees C than at 20 degrees C. Differences in the degree of cell destruction at various concentrations of potassium hydroxide were related to pH and not to osmolarity. The addition of peptones to potassium hydroxide provided a protective effect that was greater for cells suspended in Trypticase soy broth than for those suspended in phosphate-buffered sorbitol-bile salts broth. Log-phase cells were less alkalotolerant than cells in the stationary phase of growth. A modified procedure for alkali treatment, using peptone-supplemented 0.5% potassium hydroxide-0.5% sodium chloride and the addition of a pH 6.6 buffer after treatment to prevent further cell destruction, was used to observe a marked difference in alkalotolerance between Y. enterocolitica and other gram-negative bacteria. Despite this difference, alkali treatment was not highly successful for recovery of Y. enterocolitica from enrichments of seeded foods in comparison with selective enrichment in bile-oxalate-sorbose broth.     

beta-D-glucuronidase is associated with goat sperm cytoskeleton

Glycosidase activities were detected as detergent-insoluble after sequential extractions of goat sperm with Triton X-100. Seventy percent of total beta-glucuronidase activity was found in the detergent-insoluble fraction. This portion of beta-glucuronidase was resistant to extractions in the presence of 1 M KCl, chaotropic agents, colchicine, or cytochalasin B, being only partially solubilized by 3 M KCl or DNAse I treatment. The treatment with 0.1% sodium deoxycholate was effective, releasing 73% of the enzyme activity. Treating the deoxycholate extract with DNAse I resulted in a change in the elution profile of beta-glucuronidase as judged by gel filtration chromatography. A polyclonal antibody was developed against pancreatic beta-glucuronidase, and the sperm enzyme was strongly inhibited by the IgG fraction of this antibody. Western blot analysis showed that the same protein correspond to both Triton-soluble and insoluble enzyme. Results demonstrate that beta-glucuronidase is tightly bound to the Triton X-100 resistant fraction, suggesting that the enzyme is associated to sperm cytoskeleton. J. Exp. Zool. 289:146-152, 2001.     

Lysis of Yeast Cells Showing Low Susceptibility to Zymolyase

Lysis of commercial baker’s yeast cells was examined using Zymolyase. The lysis was stimulated by the addition of sodium sulfite or potassium chloride or both. The effect of potassium chloride was less than that of sodium sulfite, but the two compounds acted synergistically. The cells were effectively lysed by Zymolyase in the presence of 0.1 M sodium sulfite and 0.8 M potassium chloride. The extent of lysis was similar to that of brewery yeast cells obtained from a brewhouse. Cells pretreated with sodium sulfite did not show much of an increase in susceptibility to Zymolyase, but were effectively lysed by the enzyme in the presence of potassium chloride. Potassium chloride stimulated lysis only in the presence of Zymolyase. Yeast cells treated with cupric ions in the presence of sodium sulfite became highly susceptible to Zymolyase, suggesting irreversible destruction of the sodium sulfite-sensitive and potassium chloride-sensitive structure of the cell wall.

Cells of Saccharomyces cerevisiae prepared under various culture conditions were completely lysed by Zymolyase in the presence of sodium sulfite or potassium chloride or both.