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PubMed2002

Human and murine phenotypes associated with defects in cation-chloride cotransport.

The diuretic-sensitive cotransport of cations with chloride is mediated by the cation-chloride cotransporters, a large gene family encompassing a total of seven Na-Cl, Na-K-2Cl, and K-Cl cotransporters, in addition to two related transporters of unknown function. The cation-chloride cotransporters perform a wide variety of physiological roles and differ dramatically in patterns of tissue expression and cellular localization. The renal-specific Na-Cl cotransporter (NCC) and Na-K-2Cl cotransporter (NKCC2) are involved in Gitelman and Bartter syndrome, respectively, autosomal recessive forms of metabolic alkalosis. The associated phenotypes due to loss-of-function mutations in NCC and NKCC2 are consistent, in part, with their functional roles in the distal convoluted tubule and thick ascending limb, respectively. Other cation-chloride cotransporters are positional candidates for Mendelian human disorders, and the K-Cl cotransporter KCC3, in particular, may be involved in degenerative peripheral neuropathies linked to chromosome 15q14. The characterization of mice with both spontaneous and targeted mutations of several cation-chloride cotransporters has also yielded significant insight into the physiological and pathophysiological roles of several members of the gene family. These studies implicate the Na-K-2Cl cotransporter NKCC1 in hearing, salivation, pain perception, spermatogenesis, and the control of extracellular fluid volume. Targeted deletion of the neuronal-specific K-Cl cotransporter KCC2 generates mice with a profound seizure disorder and confirms the central role of this transporter in modulating neuronal excitability. Finally, the comparison of human and murine phenotypes associated with loss-of-function mutations in cation-chloride cotransporters indicates important differences in physiology of the two species and provides an important opportunity for detailed physiological and morphological analysis of the tissues involved.

Animals↗
PubMedDate not supplied

Kupffer cell targeting by intraportal injection of the HVJ cationic liposome.

The aim of this study was to target Kupffer cells (KCs) selectively and efficiently by the intraportal injection of fusigenic cationic liposomes with hemagglutinating virus of Japan components (HVJ cationic liposomes). Phosphorothioate FITC-oligodeoxynucleotides (FITC-ODNs) encapsulated in either HVJ cationic liposomes, HVJ anionic liposomes or conventional cationic liposomes without HVJ were transferred to the rat. FITC-ODNs in HVJ cationic liposomes administered via portal vein were selectively transfected to KCs for up to 24 h with no apparent cytotoxicity at higher transfection efficiency than FITC-ODNs in conventional cationic liposomes without HVJ administered via portal vein or tail vein. On the other hand, FITC-ODNs in HVJ anionic liposomes were observed mainly in hepatocytes, not KCs. This new method will be useful for the modulation of KCs activity in both basic research and clinical applications.

Animals↗
PubMed1996

Isolation and characterization of porcine cationic eosinophil granule proteins.

The allergic pig can be used as a large-animal model for studies of allergic reactions in the airways and the role of eosinophils in such reactions. To measure the activation of eosinophils, the release of eosinophil-derived cationic proteins can be used. The purpose of this study was to isolate and characterize cationic proteins derived from porcine eosinophils. Pigs were infested with live Ascaris suum eggs to induce eosinophilia (greater than or = 40% of leukocytes). Blood was collected and leukocytes were prepared by dextran sedimentation. Granules were obtained from the homogenized leukocytes by ultracentrifugation and cationic proteins were extracted and separated by gel filtration, cation exchange and zinc affinity chromatography. Using these methods, three cationic proteins were isolated from pig granulocytes, two of which were shown to originate from the eosinophil. The proteins were characterized according to molecular weight, amino acid composition, N-terminal sequence, isoelectric point, peroxidase and ribonuclease activity and antigenicity. One eosinophil protein was identified as eosinophil peroxidase and the other showed great similarities with human eosinophil cationic protein. The third protein was not specific for eosinophils, and had no obvious equivalent in human granulocytes. The eosinophil-derived proteins may be useful in the studies of eosinophil activation, e.g. in late-phase asthmatic reactions, where the pig represents a new candidate model for large-animal allergy research.

Amino Acid Sequence↗
PubMed1982

Calcium depletion in rabbit myocardium. Calcium paradox protection by hypothermia and cation substitution.

The purpose of this study was to define further the basis of control of myocardial membrane permeability by further examination of the "calcium paradox." To this end, the protective effect of hypothermia and addition of micromolar amounts of divalent cations during the Ca-free perfusion period were studied. Damage during Ca++ repletion to the isolated arterially perfused, interventricular rabbit septum was assessed by contracture development, loss of developed tension, and loss of 42K and creatine kinase. Progressive hypothermia prolongs the time of Ca-free perfusion needed to cause similar 42K, creatine kinase and developed tension losses upon Ca++ repletion. Complete protection against the Ca-paradox after 30-60 minutes Ca-free perfusion is seen at 18 degree C. The inclusion of 50 microM Ca++ during 30 minutes "Ca-free" perfusion also provides complete protection during Ca++ repletion i.e., there was full mechanical recovery with no 42K or creatine kinase loss. Other divalent cations perfused in 50 microM concentrations during the Ca-free period exhibited variable ability to protect when Ca++ was reperfused. The order of effectiveness (Ca++ greater than Cd++ greater than Mn++ greater than Co++ greater than Mg++) was related to the crystal ionic radius, with those cations whose radii are closest to that of Ca++ (0.99 A) exerting the greatest protective effect. The cation sequence for effectiveness in Ca-paradox protection is the same sequence for potency of excitation-contraction uncoupling. The mechanism of hypothermic protection is likely a phase transition in the membrane lipids (from a more liquid to a less liquid state) which stabilizes membrane structure and preserves Ca++ permeability characteristics during the Ca-free period. The mechanism of protection via cation addition is perhaps a cation's ability to substitute for Ca++ (dependent on unhydrated crystal ionic radius) at critical sarcolemmal binding sites to preserve control of Ca++ permability during the Ca-free period.

Animals↗
PubMed1999

Cationic proteins inhibit L-arginine uptake in rat alveolar macrophages and tracheal epithelial cells. Implications for nitric oxide synthesis.

Eosinophil-derived cationic proteins play an essential role in the pathogenesis of bronchial asthma. We tested whether cationic proteins interfere with the cationic amino-acid transport in alveolar macrophages (AMPhi) and tracheal epithelial cells, and whether L-arginine-dependent pathways were affected. The effect of cationic polypeptides on cellular uptake of [(3)H]-L-arginine, nitrite accumulation, and the turnover of [(3)H]-L-arginine by nitric oxide (NO) synthase and arginase (formation of [(3)H]-L-citrulline and [(3)H]-L-ornithine, respectively) were studied. Poly-L-arginine reduced [(3)H]-L-arginine uptake in rat AMPhi and tracheal epithelial cells in a concentration-dependent manner (at 300 microgram/ml by 70%). Poly-L-lysine, protamine, and major basic protein (each up to 300 microgram/ml) tested in rat AMPhi inhibited [(3)H]-L-arginine uptake by 35 to 50%. During 6 h incubation in amino acid-free Krebs solution, rat AMPhi, precultured in the absence or presence of LPS (1 microgram/ml), accumulated 1.4 and 3.5 nmol/10(6) cells nitrite, respectively. Addition of 100 microM L-arginine increased nitrite accumulation by 70 and 400% in control and lipopolysaccharide-treated AMPhi, respectively. Nitrite accumulation in the presence of L-arginine was reduced by poly-L-arginine and poly-L-lysine (100 and 300 microgram/ml) by 60 to 85% and 20 to 30%, respectively. Poly-L-arginine, but not poly-L-lysine, inhibited nitrite accumulation already in the absence of extracellular L-arginine. Poly-L-arginine (300 microgram/ml) inhibited [(3)H]-L-citrulline formation by AMPhi stronger than that of [(3)H]-L-ornithine. We conclude that cationic proteins can inhibit cellular transport of L-arginine and this can limit NO synthesis. Poly-L-arginine inhibits L-arginine uptake more effectively than other cationic proteins and exerts additional direct inhibitory effects on NO synthesis.

Animals↗
PubMed2004

Ion/molecule reactions of isomeric bromobutene radical cations with ammonia.

The ion/molecule reaction of the radical cations of three isomeric bromobutenes (2-bromobut-2-ene 1, 1-bromobut-2-ene 2, 4-bromobut-1-ene 3) with ammonia were studied by Fourier transform ion cyclotron resonance spectrometry to reveal the effect of a different position of the bromo substituent relative to the C-C double bond. Further, the reaction pathways of the ion/molecule reactions were analyzed by theoretical calculations at the level B3LYP/6-311+G(3df,2p)//B3LYP/6-31G(d). All three bromobutene radical cations 1(.+) to 3(.+) react efficiently with NH(3). The reactions of 1(.+) carrying the halogen substituent at the double bond follow the pattern observed earlier for other ionized vinylic halogenoalkenes. The major reaction corresponds to proton transfer to NH(3) as to be expected from the high acidity of but-2-ene radical cations exposing six acidic H atoms at allylic positions. The other, still important, reaction of 1(.+) is substitution of the Br substituent by NH(3). Although the radical cations 2(.+) and 3(.+) are expected to be as acidic as 1(.+), proton transfer is the minor reaction pathway of these radical cations. Instead, 2(.+) displays bomo substitution as the major reaction. It is suggested that the mechanism of this reaction is analogous to S(N)2' of nucleophilic allylic substitution. Substitution of Br is not efficient for the reactions of 3(.+)-the two major reactions correspond to C-C bond cleavage of the two possible beta-distonic ammonium ions which are generated by the addition of NH(3) to the ionized double bond of 3. This observation, as well as the results obtained for 1(.+) and 2(.+), emphasize the role of the fast and very exothermic addition of a nucleophile to the ionized double bond for the ion/molecule reactions of alkene radical cations. Clearly the energetically-excited distonic ion arising from the addition fragments unimolecularly by energetically accessible pathways. In the case of a halogene subsituent (except F) at the vinylic or allylic position, this is loss of thesubsituent. In the case of remote halogeno substituents, this is C-C bond cleavage adjacent to the radical site of the distonic ion.

Journal Article↗
PubMed1994

Preferential adsorption of cationic anti-DNA antibodies with immobilized polyanionic compounds, dextran sulfate.

It has been shown that cationic anti-DNA antibodies have nephritogenic potential in murine models of lupus nephritis. More recently, we have reported that there is a close relationship between the presence of circulating cationic anti-DNA antibodies and the development of lupus nephritis in humans, and that the cationic anti-DNA antibodies bind to heparan sulfate, a major glycosaminoglycan in glomerular basement membrane, much better than neutral anti-DNA antibodies. This suggests that cationic anti-DNA antibodies of the IgG class may be responsible for development of nephritis in vivo in patients with systemic lupus erythematosus. In this study, we first studied reactivity of anti-DNA antibodies with a panel of glycosaminoglycans in vitro using ELISA methods, and found that anti-DNA antibodies cross-react with dextran sulfate, hyaluronic acid and chrondroitin sulfate. The reactivity and selectivity of dextran sulfate with anti-DNA antibodies was confirmed by in vitro immunoadsorption of the patient's sera with dextran sulfate-fixed column; incubation of auto-antibody-positive sera with dextran sulfate cellulose column removed anti-DNA, but not anti-RNP, anti-Sm, anti-SSA and anti-SSB antibodies from the sera in vitro. Of note is that dextran sulfate cellulose column absorbed exclusively, if not all, cationic anti-DNA antibodies in their sera. Nonspecific binding of total immunoglobulins as well as total proteins to the column was marginal. It has been suggested that cationic anti-DNA antibodies in sera of patients with refractory lupus nephritis could be efficiently removed by apheresis using dextran sulfate column.

Adolescent↗
PubMed2000

Encapsulation of plasmid DNA in stabilized plasmid-lipid particles composed of different cationic lipid concentration for optimal transfection activity.

In previous work (Wheeler et al. (1999) Gene Therapy 6, 271-281) we have shown that plasmid DNA can be entrapped in "stabilized plasmid lipid particles" (SPLP) using low levels (5-10 mol%) of cationic lipid, the fusogenic lipid dioleoylphosphatidylethanolamine (DOPE), and a polyethyleneglycol (PEG) coating for stabilization. The PEG moieties are attached to a ceramide anchor containing an arachidoyl acyl group (PEG-CerC20). However, these SPLP exhibit low transfection potencies in vitro as compared to plasmid/cationic lipid complexes formed with liposomes composed of cationic and neutral lipid at a 1:1 lipid ratio. The objective of this study was to construct SPLPs with increased cationic lipid contents that result in maximum transfection levels. A phosphate buffer detergent dialysis technique is described resulting in formation of SPLP containing 7-42.5 mol% DODAC with reproducible encapsulation efficiency of up to 80%. An octanoyl acyl group was used as anchor for the PEG moiety (PEG-CerC8) permitting a quick exchange out of the SPLP to further optimize the in vitro and in vivo transfection. We have demonstrated that this technique can be used to encapsulate either linearized DNA or supercoiled plasmids ranging from 3-20 kb. The SPLP formed could be isolated from empty vesicles by sucrose density gradient centrifugation, and exhibited a narrow size distribution of approximately 75 +/- 6 nm as determined by cryo-electron microscopy. The high plasmid-to-lipid ratio observed corresponded to one plasmid per particle. The SPLP consist of a lipid bilayer surrounding the plasmid DNA as visualized by cryo-electron microscopy. SPLP containing a range of DODAC concentrations were tested for in vitro and in vivo transfection. In vitro, in COS-7 cells transfection reached a maximum after 48 h. The transfection efficiency increased when the DODAC concentration in the SPLP was decreased from 42.5 to 24 mol% DODAC. Decreasing the cationic lipid concentration improved transfection in part due to decreased toxicity. In vivo studies using an intraperitoneal B16 tumor model and intraperitoneal administration of SPLP showed maximum transfection activity for SPLP containing 24 mol% DODAC. Gene expression observed in tumor cells was increased by approximately one magnitude as compared to cationic lipid/DNA complexes. The SPLP were stable and upon storage at 4 degrees C no significant change in the transfection activity was observed over a one-year period. Thus this phosphate buffer detergent dialysis technique can be used to generate SPLP formulations containing a wide range of cationic lipid concentrations to determine optimal SPLP composition for high transfection activity and low toxicity.

Animals↗
PubMed1991

Addition of chloride to a prepartal diet high in cations increases 1,25-dihydroxyvitamin D response to hypocalcemia preventing milk fever.

In this study, we present evidence that cows fed highly cationic diets are less responsive to parathyroid hormone than those fed a highly anionic diet. Forty-seven Jersey cows (55 mo of age) were fed an alfalfa haylage-based diet supplemented with either anions (Cl-) or cations (Na+). Cows fed the high cationic diet suffered significantly more cases of milk fever (6 out of 23) than those fed the high anionic diet (1 out of 24). Concentrations of Ca at parturition and the first 2 d of lactation were significantly higher in cows fed the anionic diet. Secretion of parathyroid hormone in response to developing hypocalcemia was similar in cows fed either diet. Plasma hydroxyproline concentration (an index of bone Ca resorption activity) was greater in cows fed the anionic diet, suggesting better utilization of bone Ca. Plasma 1,25-dihydroxyvitamin D concentration was correlated inversely with plasma Ca and related directly to plasma parathyroid hormone in both groups of cows. However, the magnitude of the response (the amount of 1,25-dihydroxyvitamin D produced per unit increase in parathyroid hormone) was reduced greatly in cows fed the high cation diet. Because parathyroid hormone regulates both bone Ca resorption and renal 1,25-dihydroxyvitamin D production, these data suggest that prepartal diets high in cations decrease the ability of bone and renal tissues to respond to parathyroid hormone. Addition of anions to prepartal diets can reduce the excess cation balance of diets, increasing tissue response to parathyroid hormone and enabling the cow to better adapt to the Ca demands of lactation.

Animal Feed↗
PubMed1988

Schistosoma mansoni cationic egg antigens (CEF6): immunoserology with oxamniquine-treated patients and involvement of CEF6 in the circumoval precipitin reaction.

The serologic activity of a cationic fraction (denoted CEF6) of Schistosoma mansoni soluble egg antigen was compared in an ELISA with that of the unpurified soluble egg antigen for the ability to detect human infections and for the prediction of chemotherapeutic success in patients followed up to 5 years post-treatment with oxamniquine. The cationic fraction correctly identified 100% of 20 patients as infected with S. mansoni; moreover, 50% (10 of 20) seroconverted to negative by 2 years post-treatment and 100% of 15 patients tested were negative 5 years post-treatment. In general, the cationic fraction was superior to the unpurified soluble egg antigen for the detection of infection and for the prediction of chemotherapeutic success. The cationic fraction also exhibited greater immunologic specificity over the unpurified soluble egg antigen in that the latter exhibited higher titers than the former to antibodies against heterologous parasite antigens (Fasciola hepatica, Clonorchis sinensis, Paragonimus westermani adult worms; Trichinella spiralis larvae). Moreover, rabbit antisera raised against egg antigens isolated from the precipitation formed when fresh S. mansoni eggs are incubated with S. mansoni infection of immunization sera (known as circumoval precipitin reactions or COP) reacted strongly with the cationic fraction in ELISA. In addition, antiserum to the cationic fraction as well as antisera against either of the two antigenic components of this fraction, known as antigens alpha 1 and omega 1, all give positive COP reactions when incubated with fresh S. mansoni eggs.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2002

[Influence on human keratocyte proliferation by cationic liposome mediated transfer of p21WAF1].

OBJECTIVE: The aim of this study is to investigate the safety and efficiency of transducing human keratocytes with beta-galactosidase gene through cationic liposome and evaluate the influence of p21WAF1 gene transduction mediated by cationic liposome on proliferation of keratocyte. METHODS: (1) Cationic liposome mediated plasmid DNA bearing beta-galactosidase gene was transferred into cultured human keratocyte, and transduction efficiency was evaluated by enzymatic color reaction using X-gal as a substrate. (2) By immunohistochemistry and MTT, the effect of p21WAF1 gene transduction mediated by cationic liposome on cultured keratocyte proliferation was evaluated. (3) Cellular viability was detected by 0.5% trypan blue dye. RESULTS: (1) Lipofectaminetrade mark reagent could mediate a foreign gene into a cultured human keratocyte, and the highest transduction efficiency was 40.5% when DNA/lipofectamine ratio was 1:8 and the transduction time was 24 hr. (2) p21WAF1 gene transduction mediated by lipofectaminetrade mark reagent could increase the p21 protein expression in the keratocyte, and inhibit the keratocyte proliferation during 2 - 10 days after transduction. And rates of cellular viability in all groups were greater than 90% by trypan blue dye examination. CONCLUSION: Cationic liposome can mediate foreign gene into cultured human keratocytes safely and effectively; p21WAF1 gene transduction mediated by cationic liposome can inhibit the proliferation of human keratocyte.

Cell Division↗
PubMed1975

[The cytochemistry of antibacterial cationic proteins of leukocytes during phagocytosis and inflammation].

The article deals with data on lysosomal cationic proteins. Many properties of cationic proteins of leucocytes justify the assumption about their possible genetic affinity to nuclear histones. A high antibacterial activity of cationic proteins justified a more profound investigation into their role in phagocytosis and in formation of anti-infectious resistance in inflammation foci. The question concerning cationic proteins as mediators of inflammation is discussed. The suggested methods for staining cationic proteins may be used in determination of the fate of phagocytized bacteria, in studies of cytochemistry of cationic proteins of leucocytes, in identifying viable and perished bacteria in inflammation foci in bacterial infectious processes.

Animals↗
PubMed2003

[Reflectance spectra of J-aggregates of anionic-cationic cyanine dyes adsorbed on AgBrI microcrystal].

Spectral sensitivity is a key technology of modern photography. Because J-aggregates of cyanine dye exhibit sharp absorption bands (i.e., J-band), they are important sensitizers. In this article, the J-aggregation behavior of two kinds of anionic-cationic cyanine dyes adsorbed on the AgBrI cubic microcrystals was studied. The reflectance spectral curves of J-aggregating dyes were measured by UV-Vis. spectrophotometer, and were compared with the J-aggregation of anionic and cationic cyanine dyes. The results show that the reflectance spectra of J-aggregates of anionic-cationic cyanine dyes adsorbed on AgBrI microcrystals have peak wavelengths of anionic and cationic cyanine dyes. Anionic-cationic cyanine dyes have two sensitivity regions, including both the sensitivity region of anionic cyanine dye and the sensitivity region of cationic cyanine dye.

English Abstract↗
PubMed1991

Eosinophil cationic protein's role in human hepatic allograft rejection.

Although it is known that eosinophils consistently infiltrate rejecting human liver allografts, their function is unknown. Infiltrating eosinophils can release a cytotoxic substance, eosinophil cationic protein. Furthermore, eosinophil cationic protein may be identified in biopsy specimens using immunoperoxidase staining of an eosinophil cationic protein-specific monoclonal antibody. To study a possible effector role of eosinophils in rejecting liver allografts, 38 serial allograft biopsy specimens from 12 patients with acute rejection, 54 biopsy specimens from 11 patients with allograft dysfunction caused by other causes and 22 biopsy specimens from 8 patients without allograft dysfunction were stained for extracellular eosinophil cationic protein. In addition, the absolute blood eosinophil counts and the portal tract eosinophil percent of the total number of portal tract inflammatory cells were tabulated in these patients until 30 days after transplantation. The blood absolute eosinophil count, portal tract eosinophil percent and incidence of positive extracellular eosinophil cationic protein staining were significantly increased in patients with rejection compared with patients with dysfunction from other causes (p less than 0.05 to 0.005, t test). Furthermore, each of these parameters predicted rejection with excellent sensitivity (75% to 92%) and specificity (91% to 100%). Of patients with rejection, 59% had significant elevation of all three parameters before or during rejection, and 92% had at least two parameters elevated. Conversely, of the patients with dysfunction from other causes, 0% had elevations of any parameter. The recognized cytotoxic properties of eosinophil cationic protein and its almost exclusive presence, along with eosinophils in the blood and allograft biopsy specimens of patients during acute rejection, support the role of the eosinophil as an effector cell in tissue injury during acute liver allograft rejection.

Blood Proteins↗
PubMed1990

Effect of endogenous and exogenous polyamines on organic cation transport in rabbit renal plasma membrane vesicles.

The effect of several polyamines on the transport of organic cations [N1-[3H]methylnicotinamide (NMN), [3H]NMN and 3H-tetraethylammonium, ([3H]TEA)] in rabbit renal brush border (BBMV) and basolateral membrane vesicles (BLMV) was studied using a rapid filtration assay. Under pH-driven conditions in BBMV, [3H]NMN transport was cis inhibited approximately 30% by the naturally occurring polyamines (cadaverine, putrescine, spermine and spermidine) and nearly 90% by methylglyoxal bis(guanylhydrazone) (MGBG), a synthetic polyamine, mepiperphenidol and cimetidine, classical organic cation transport inhibitors. In the absence of a pH gradient, the capability of these agents to block [3H]NMN transport was diminished. The capability of these compounds to translocate the membrane was assessed by examining the phenomenon of counterflow. TEA, mepiperphenidol and MGBG produced trans stimulation of TEA uptake, whereas putrescine did not. Kinetic studies revealed that both putrescine and MGBG affected the Km value for TEA transport while having a minimal effect on the Vmax value. These results are most consistent with competitive inhibition. The specificity of polyamine inactivation of organic cation transport was assessed by examining what effect they had on the transport of another brush border transporter, D-glucose. These agents did not inhibit D-glucose transport. In addition, the effect of polyamines on the transport of organic cations in BLMV was studied. Only MGBG, cimetidine and mepiperphenidol inhibited organic cation transport. The results indicate that endogenous polyamines cis inhibited the organic cation transporter in BBMV competitively, whereas the exogenous polyamine MGBG cis inhibited competitively and produced trans stimulation. In contrast in BLMV, only MGBG was an effective inhibitor.

Animals↗
PubMed1990

A small proportion of cationic antibodies in immune complexes is sufficient to mediate their deposition in glomeruli.

Positively charged antibodies mediate enhanced deposition of circulating immune complexes at the glomerular basement membrane. The presented experiments demonstrate that when soluble immune complexes were prepared with a mixture of antibodies containing 10 to 25% cationic antibodies, then noncationic antibodies in the complexes were deposited in mouse glomeruli. One or two cationic antibodies in each immune complex sufficed for deposition of the complexes. Proof for this was obtained by two kinds of experiments. First, the injected immune complexes were prepared in Ag excess from mixtures of radiolabeled noncationic rabbit antibodies to human serum albumin (HSA) and unlabeled cationized rabbit antibodies to HSA, thus permitting the specific quantitation of the deposition of noncationic antibodies in glomeruli because of the presence of cationized antibodies within the same complexes. As a control experiment, immune complexes prepared only with noncationic antibodies resulted in very little deposition in kidneys over the same time period. Second, detection of the localization of the noncationic antibody in deposits in glomeruli by immunofluorescence microscopy was accomplished using immune complexes prepared with mixtures of noncationic goat antibodies to HSA and cationized rabbit antibodies to HSA. Thus, the synthesis of a small population of cationic antibodies during the immune response may lead to the formation of circulating immune complexes with enhanced propensity for deposition in glomeruli in patients with SLE or other immune complex diseases.

Animals↗
PubMed1988

Influence of cations on the blue to purple transition of bacteriorhodopsin. Comparison of Ca2+ and Hg2+ binding and their effect on the surface potential.

We have investigated the effect of Ca2+ and Hg2+ binding on various properties of the blue membrane prepared by deionization of the Halobacterium halobium purple membrane. Binding of radioactive 45Ca2+ and 203Hg2+ was monitored by a filtration technique. Five high and medium affinity sites for Ca2+ and seven low affinity sites for Hg2+ were found per bacteriorhodopsin. Competitive binding was observed only for three Ca2+ and three Hg2+. Visible absorption studies indicated that Ca2+ binding could restore the purple color of bacteriorhodopsin while Hg2+ was inefficient. Hg2- could partially reverse to blue the Ca2+-regenerated purple membrane in parallel with the displacement of three Ca2+. Effects of cation binding on the surface potential of the membrane were measured by Electron Spin Resonance spectroscopy using a cationic spin-labeled amphiphile. Cations such as La3+, Ca2+, Mg2+, or Na+ strongly increased (i.e. rendered less negative) the surface potential. An univocal correlation was found between the cation-induced variation of surface potential and the extent of regeneration of the purple color. Hg2+ induced a smaller increase in surface potential than that corresponding to the effective divalent cations. This lower effect appears to be due to binding to sites not related to those of other cations.

Bacteriorhodopsins↗
PubMed1987

Relevance of cation-exchange capacity of cell wall in detecting H+-symport in yeasts.

Addition of mono- or divalent cations to unbuffered yeast suspensions causes acidification of the medium. In some yeasts (Rhodotorula glutinis and Metschnikowia reukaufii) this represented a mediated H+ extrusion in exchange for cations (mostly K+). However, in some other yeasts (Pichia humboldtii and Candida albicans) the pH change was very rapid. The rapid acidification of the media by Pichia humboldtii was found to be due to high cation-exchange capacity of its cell wall. This cation-exchange was saturable, exhibited high affinity for divalent cations and was stoichiometric under appropriate experimental conditions. Results suggest that such cation exchange capacity of some yeasts could hamper the measurements related to H+-symport mechanisms.

Cell Wall↗