Inhibitory effect of phosphatidylserine on iron-dependent lipid peroxidation

The effect of phospholipids on lipid peroxidation was investigated in liposomal suspension of egg yolk phosphatidylcholine. Both saturated and unsaturated phosphatidylserine effectively inhibited lipid peroxidation induced by ferrous-ascorbate system in the presence of phosphatidylcholine hydroperoxides. Studies on the iron trapping effect of phospholipids indicated that the effectiveness of inhibition depends on the charge of phosphatidylserine that binds to free ionic iron.     

Profiles of enterotoxin and cytotoxin production in Campylobacter jejuni and C. coli

Enterotoxin and cytotoxin production of 10 strains of Campylobacter spp. were examined by ELISA and HeLa cells assay, respectively. Both toxins were produced in high concentrations by strains freshly isolated from patients. The maximum enterotoxin activity was found to be at 24 h after incubation, at which time cell growth reached the stationary phase. On the other hand, production of cytotoxin increased after the logarithmic phase of the growth.     

Purification, molecular cloning, and genomic organization of human brain long-chain acyl-CoA hydrolase

An acyl-CoA hydrolase, referred to as hBACH, was purified from human brain cytosol. The enzyme had a molecular mass of 100 kDa and 43-kDa subunits, and was highly active with long-chain acyl-CoAs, e.g. a maximal velocity of 295 micromol/min/mg and K(m) of 6.4 microM for palmitoyl-CoA. Acyl-CoAs with carbon chain lengths of C(8-18) were also good substrates. In human brain cytosol, 85% of palmitoyl-CoA hydrolase activity was titrated by an anti-BACH antibody, which accounted for over 75% of the enzyme activity found in the brain tissue. The cDNA isolated for hBACH, when expressed in Escherichia coli, directed the expression of palmitoyl-CoA hydrolase activity and a 44-kDa protein immunoreactive to the anti-BACH antibody, which in turn neutralized the hydrolase activity. The hBACH cDNA encoded a 338-amino acid sequence which was 95% identical to that of a rat homolog. The hBACH gene spanned about 130 kb and comprised 9 exons, and was mapped to 1p36.2 on the cytogenetic ideogram. These findings indicate that the long-chain acyl-CoA hydrolase present in the brain is well conserved between man and the rat, suggesting a conserved role for this enzyme in the mammalian brain, and enabling genetic studies on the functional analysis of acyl-CoA hydrolase.     

Three isoforms of cyclophilin A associated with human immunodeficiency virus type 1 were found by proteomics by using two-dimensional gel electrophoresis and matrix-assisted laser desorption ionization-time of flight mass spectrometry

Human immunodeficiency virus type 1 (HIV-1) strain LAV-1 (HIV-1(LAV-1)) particles were collected by ultracentrifugation, treated with subtilisin, and then purified by Sepharose CL-4B column chromatography to remove microvesicles. The lysate of the purified HIV-1(LAV-1) particles was subjected to two-dimensional (2D) gel electrophoresis and stained. The 2D gel electrophoresis image suggested that 24 proteins can be identified inside the virion. Furthermore, the stained protein spots were excised and digested with trypsin. The resulting peptide fragments were characterized by matrix-assisted laser desorption ionization-time of flight mass spectrometry. Peptide mass fingerprinting data suggested that two isoforms of cyclophilin A (CyPA), one with an isoelectric point (pI) of 6.40 and one with a pI of 6.53, are inside the viral membrane; that another isoform, with a pI of 6.88, is outside the viral membrane; and that the CyPA isoform with a pI of 6.53 is N acetylated. The mechanisms that permit the redistribution of CyPA on the viral surface have not yet been clarified, but it is surmised that the CyPA isoform with a pI of 6.88 may play a critical role in the attachment of virions to the surface of target cells and that both CyPA isoforms with pIs of 6.40 and 6.53 may regulate the conformation of the HIV-1 capsid protein.     

Hypokalemia and sodium retention in patients with diabetes and chronic hepatitis receiving insulin and glycyrrhizin

Of 9 patients with chronic hepatitis treated with intravenous administration of 40 to 200 mg/day of glycyrrhizin, 3 diabetic patients receiving concomitant insulin developed hypokalemia, sodium retention and suppression of both plasma aldosterone concentration and plasma renin activity after the administration for 3 to 6 days. In the remaining 6 patients (5 nondiabetic and 1 diabetic) receiving no insulin, the administration over the long term (18 to 266 days) never caused these abnormalities. The development of hypokalemia and sodium retention in the patients was not associated with increased urinary excretion of potassium, indicating a different condition from pseudoaldosteronism caused by the desoxycorticosterone-like action of glycyrrhizin. These findings suggest that insulin which is known to have hypokalemic, antinatriuretic and antikaliuretic activity, as well as glycyrrhizin plays an important pathogenetic role in the observed electrolyte disturbance, and suppression of both renin and aldosterone.     

Changes in cell morphology and polyamine composition during growth of Campylobacter jejuni

Resting cells of Campylobacter jejuni were spherical whereas growing cells were mainly spiral. Content of cadaverine increased with the decrease in spherical forms prior to growth commencing but production of spermidine increased in early log phase. Cadaverine and spermidine are possibly involved in changes in cell morphology and growth, respectively.S. Suzuki is with the Faculty of Agriculture, Kochi University, Nankoku, Kochi 783, Japan; Y. Horikoshi and K. Takama are with the Faculty of Fisheries, Hokkaido University, Hakodate, Hokkaido 041, Japan.     

Selectivity in mobilisation of stored fatty acids by maturing cod, Gadus morrhua L

Lipids, proteins and carbohydrates diminish in the liver and muscle of cod when (a) food is inadequate or (b) the gonads are maturing. The results reported in this paper appear to show that the mobilisation of the lipids differs according to whether the need is just for energy (simple starvation) or for building up gonads. Two groups of fish from the same catch were starved. In one, the gonads were developing, while in the other the gonads had been surgically removed. Significantly more of the fatty acid C22:6 was mobilised from the liver lipids in the group with developing gonads, this fatty acid being present in the greatest amount in the gonads of either sex. The fatty acid C18:1 is also important in the gonads, and this was also preferentially removed from all the livers of maturing-starving fish when compared with gonadectomised-starving, though here the effect was not statistically significant. Some discrimination therefore appears to be exercised when hepatic lipids are removed for gonad development. No selectivity was observed in the mobilisation of fatty acids from the muscle.     

Ultracytochemistry of pancreatic damage induced by excess lysine

The ultracytochemical changes induced in the pancreas by a single large dose of lysine (400 mg/100 g body weight) were studied in male Wistar rats of 7 weeks old. The first changes in the acinar cells were marked swelling of mitochondria with increase in their calcium content and decrease in their ATP content. Early calcium deposits seemed to occur in the matrices of swollen mitochondria and later various patterns occurred. These findings suggested that damage of the acinar cells by excess lysine resulted in breakdown of the mitochondrial membrane barrier to calcium as a very early abnormality, and that extracellular calcium then entered the mitochondrial matrices and inhibited mitochondrial function. Subsequently focal areas of the cytoplasm were degraded. Autophagic vacuoles appeared in these areas, and then acid phosphatase activity in their periphery as a result of fusion with lysosomes. The reaction of acid phosphatase was demonstrated in the locally degraded rough endoplasmic reticulum within or around autophagic vacuoles, suggesting that the endoplasmic reticulum as well as lysosomes participated in the intracellular degradation of cytoplasmic organelles in damaged acinar cells.