Effect of triethylenepentaminehexaacetic acid on the renal damage in cadmium-treated Syrian hamsters

Cadmium (Cd)-induced nephropathy was treated by triethylene-pentaminehexaacetic acid (TTHA) in male Syrian hamsters. Hamsters injected three times a week with 3 mg/kg body wt CdCl₂ showed proteinuria, urinaryN-acetyl-β-d-inglucosaminidase (NAG), and fractional excretion of sodium (FENa) when compared to saline-injected control. Cd-treated hamsters injected ip with TTHA 10 mg/kg body wt five times a week showed reduction of renal damage, including reductions in urinary protein (from 6.7±2.2 to 4.3±0.5 mg/d) and NAG (0.17±0.06 to 0.04±0.02 U/d). Urinary excretion of Cd was significantly increased (from 87±51.3 to 3052±1485 mg/L) by TTHA administration. Cd concentration in renal cortical tissue was slightly reduced (26.4±3.0 to 21.8±2.7 mg/g. protein). Excretion of malondialdehyde (MDA) was increased only in Cd-injected hamsters (to 2.1±1.6 nM/L), and elevated MDA in renal cortical tissue was not reduced by the administration of TTHA (1041±105 vs 1104±358 nM/g protein). Glutathione (GSH) concentration in the renal cortex was significantly elevated after Cd administration and further increased after TTHA administration (5.5±2.1 to 9.8±2.0 μg/50 mg protein). There were no marked effects on creatinine clearance (Ccr) and hematocrit. Moreover, renal morphological changes were improved significantly by treatment with TTHA. We demonstrated the efficacy of TTHA in the treatment of Cd-induced nephropathy in hamsters. Although the precise mechanism of the TTHA effects on Cd-induced nephropathy has not been elucidated, it might involve GSH reducing the elevated MDA concentration in renal tissue.     

Study of interaction between calcium and zinc ond-galactose intestinal transport

Zinc is an essential trace element necessary to life. This metal may exert some of its physiological effects by acting directly on cellular membranes, either by altering permeability or by modulating the activity of membrane-bound enzymes. On the other hand, calcium is an essential element in a wide variety of cellular activities. The aim of the present work was to study a possible interaction between zinc and calcium on intestinal transport ofd-galactose in jejunum of rabbit in vitro. In media with Ca²⁺, when ZnCl₂ was present at 0.5 or 1 mM, zinc was found to reduce thed-galactose absorption significantly. In Ca²⁺-free media, where CaCl₂ was omitted and replaced isotonically with choline chloride, the sugar transport was not modified by zinc. Verapamil at 10⁻⁶ M (blocking mainly Ca²⁺ transport) did not modify the inhibitory effect of zinc ond-galactose transport. When 10⁻⁶ M of A 23187 (Ca²⁺-specific ionophore) was added with/without Ca²⁺ to the media, ZnCl₂ produced no change in sugar transport. These results could suggest a possible interaction of calcium and zinc for the same chemical groups of membrane, which could affect the intestinal absorption of sugars.     

The potential applications of cyanobacterial photosynthesis for clean technologies

Natural photosynthesis may be adapted to advantage in the development of clean energy technologies. Efficient biocatalysts that can be used in solar energy conversion technologies are the cyanobacteria. Photobioreactors incorporating cyanobacteria have been used to demonstrate (a) the production of hydrogen gas, (b) the assimilation of CO₂ with the production of algal biomass, (c) the excretion of ammonium, and (d) the removal of nitrate and phosphate from contaminated waters.Abbreviations Chl chlorophyll - DW dry weight - MSX L-methionine-D-L-sulphoximine - PAR photosynthetically active radiation - PU polyurethane - PV polyvinyl - PVC polyvinylchloride     

d-Alanine metabolism in the lucinid clam Lucinoma aequizonata

The chemoautotrophic symbiont-bearing clam Lucinoma aequizonata contains very high levels of free d-alanine in all tissues. The possible sources for this amino acid and its involvement in the clams' metabolism were investigated. Very low levels of d-alanine (generally below 1 mol·l^-1) were measured in the sediment porewaters from the habitat of the clams. Experiments with ¹⁴C-labeled tracers demonstrate an active metabolism of d-alanine in the clams rather than a role as inert waste product. d-alanine is metabolized at about 0.12 mol·g fw^-1·h^-1. Label from aspartate, but not glucose and CO₂, is incorporated into d-alanine. Incubation with labeled d-alanine did not result in formation of radioactive l-alanine. Tests for alanine racemase (EC 5.1.1.1) and d-amino acid oxidase (EC 1.4.3.3.) did not show activity in either gill, i.e. symbiont and host, or foot tissue. d-Alanine amino transferase (EC 2.6.1.b.) was demonstrated in gill and foot tissues. Two sources for d-alanine are proposed: a degradation of cell walls of symbiotic bacteria and production by the host using a d-specific alanine transaminase.Abbreviations aa amino acid(s) - fw fresh weight - HPLC high-performance liquid chromatography - MBH methyl benzethonium hydroxyde - NAC N-acetyl-l-cysteine - OPA ortho-phthaldialdehyde - TCA tricarbonic acid     

Amino acid sequence of the minor isomorph of the crustacean hyperglycemic hormone (CHH-II) of the Mexican crayfish Procambarus bouvieri (Ortmann): Presence of a d-amino acid

The primary structure of the neurohormone crustacean hyperglycemic hormone (CHH-II) was determined by means of enzymatic digestions, manual Edman degradation, and mass spectrometry. CHH-II is a 72 residue peptide (molecular mass 8388 Da), with six cysteines forming three disulfide bridges that connect residues 7–43, 23–39, and 26–52. The peptide has blocked N- and C-termini, and lacks tryptophan, histidine, and methionine. The CHH-I and CHH-II of Procambarus bouvieri have identical sequences and elicit levels of hyperglycemia that are not distinguishable. The difference between the two isomorphs consists in a posttranslational modification of a l-Phe in CHH-I to a d-Phe in CHH-II at the third position from the N-terminus.     

Sodium channels in cultured neuroblastoma cells grown in high glucose or l-Fucose

Patch clamp techniques were used to record whole cell and single channel Na⁺ currents from NB41A3 neuroblastoma cells grown in culture. Cells were grown for two weeks in control medium or medium supplemented with 30 mm d-glucose of 30 mm l-fucose.Cells exposed to glucose or l-fucose had smaller whole cell Na⁺ currents than cells grown in unsupplemented medium, consistent with earlier studies (Yorek, Stefani & Wachtel, 1994). Whole cell macroscopic currents showed no change in activation or inactivation kinetics. Single channel current properties and opening probability were also unchanged.The number of [³H]saxitoxin binding sites, and therefore the total number of Na⁺ channels, was not reduced in cells grown in glucose or l-fucose (Yorek et al., 1994). Therefore, we conclude that some of the channels must have been rendered nonfunctional by the conditioning media. The finding that single channel properties are not altered suggests that channels become nonfunctional in an all-or-none manner.This work was supported by Merit Review Awards to M.A. Yorek and R.E. Wachtel from the Department of Veterans Affairs and by National Institutes of Health grant DK45453 to M.A. Yorek.     

l-Fucose residues on cellulose-based dialysis membranes: Quantification of membrane-associatedl-fucose and analysis of specific lectin binding

Contact of mononuclear human leukocytes with cellulose dialysis membranes may result in complement-independent cell activation, i.e. enhanced synthesis of cytokines, prostaglandins and an increase in 2-microglobulin synthesis. Cellular contact activation is specifically inhibited by the monosaccharidel-fucose suggesting that dialysis membrane associatedl-fucose residues are involved in leukocyte activation. In this study we have detected and quantitatedl-fucose on commercially-available cellulose dialysis membranes using two approaches. A sensitive enzymatic fluorescence assay detectedl-fucose after acid hydrolysis of flat sheet membranes. Values ranged from 79.3±3.6 to 90.2±5.0 pmol cm^–2 for Hemophan® or Cuprophan® respectively. Enzymatic cleavage of terminal -l-fucopyranoses with -l-fucosidase yielded 7.7±3.3 pmoll-fucose per cm² for Cuprophan. Enzymatic hydrolysis of the synthetic polymer membranes AN-69 and PC-PE did not yield detectable amounts ofl-fucose. In a second approach, binding of the fucose specific lectins ofLotus tetragonolobus andUlex europaeus (UEAI) demonstrated the presence of biologically accessiblel-fucose on the surface of cellulose membranes. Specific binding was observed with Cuprophan®, and up to 2.6±0.3 pmoll-fucose per cm² was calculated to be present from Langmuir-type adsorption isotherms. The data presented are in line with the hypothesis that surface-associatedl-fucose residues on cellulose dialysis membranes participate in leukocyte contact activation.     

Origin ofd-serine present in urine of mutant mice lackingd-amino-acid oxidase activity

Summary Urine of ddY/DAO mice lackingd-amino-acid oxidase contained 5.7 times more serine than that of normal ddY/DAO⁺ mice. Most of the serine wasd-isomer. The origin of this^d-serine was examined. Oral administration of 0.02% amoxicillin and 0.004% minocycline to the ddY/ DAO^- mice for 7 days did not reduce the urinaryd-serine, indicating that thed-serine was not of intestinal bacterial origin. When the mouse diet was changed to one with different compositions, the urinaryd-serine was considerably reduced. Furthermore, starvation of the ddY/DAO^- mice for 24 hours reduced the urinaryd-serine to 33% of the original level. These results indicate that most of the urinaryd-serine comes from the diet. However, the urine of the starved ddY/DAO^- mice still contained 4.6 times mored-serine than that of the ddY/DAO⁺ mice, suggesting a part of the D-serine have an endogenous origin.     

Emerging mechanisms of the behavioral effects of steroids

Within two models of steroid-modulated behavior, sodium appetite and sexual receptivity, novel mechanisms of steroid action have emerged. These include interactions between different types of steroid receptors, plasticity of synapses, activation of unliganded steroid receptors, and rapid effects of steroids. These mechanisms highlight the diversity of steroid action in the central nervous system.     

Chemical characterization of two lipopolysaccharide species isolated from Rhizobium loti NZP2213

Phenol-water extraction of Rhizobium loti NZP2213 cells allowed a simultaneous isolation of two structurally different lipopolysaccharides, from the aqueous (LPS-W) and phenol (LPS-P) phase that differed in their sodium doexycholate-PAGE pattern and composition. LPS-W showed a profile indicating an R-type LPS; LPS-P had a cluster of poorly resolved bands in the high-molecular-weight region. LPS-P contained large amounts of 6-deoxy-l-talose (6dTal), and a small amount of 2-O-methyl-6-deoxy-talose (molar ratio 30:1), both of which were completely absent in LPS-W. Methylation analysis gave only one major product, 2,4-di-O-methyl-6dTal, indicating that the O-chain is composed of a homopolymer of 1,3-linked 6dTal, having the methylated 6dTal (2-O-me-6dTal) probably localized at the non-reducing end of the O-chain. This homopolymeric O-chain was additionally O-acetylated, as evidenced by GC-MS and by ¹³C NMR analysis. The lipid A moieties of both LPS-W and LPS-P showed almost identical composition, with six, different 3-OH fatty acids and with two, so far not described, long-chain 4-oxo-fatty acids, all being amide-linked, and with 27-OH-28:0 as the main ester-linked fatty acid. Lipid A was of the lipid A_DAG-type, i.e., having a (phosphorylated) 2,3-diamino-2,3-dideoxy-d-glucose-containing lipid A backbone. Lipid A_DAG is widespread among species of the -2 group of Proteobacteria, but has so far not been encountered in any other rhizobial or agrobacterial species.