Liver fatty acid-binding protein in two cases of human lipid storage

Summary FABPs in the various tissues play an important role in the intracellular fatty acid transport and metabolism. Reye's syndrome (RS) and multisystemic lipid storage (MLS) are human disorders characterized by a disturbance of lipid metabolism of unknown etiology. We investigated for the first time L-FABP in these two conditions. Affinity purified antibodies against chicken L-FABP were raised in rabbits, and found to cross-react specifically with partially purified human L-FABP. L-FABP content in liver samples of two patients with RS and MLS was investigated by immuno-histochemistry, SDS-PAGE and ELISA. L-FABP immuno-histochemistry showed increased reactivity in the liver of RS patient and normal reactivity in MLS liver. L-FABP increase in RS liver was confirmed by densitometry of SDS-PAGE and ELISA method. By these two methods the increase amounted to 180% and 199% (p < 0.02), respectively, as compared to controls. A possible role of L-FABP in the pathogenesis of RS is discussed.     

Studies on human uterine cervix and rat uterus using S-, X- and Q-band electron-spin-resonance spectroscopy.

In previous studies we have reported on the detection of a strong e.s.r. signal in samples of normal human cervix; the signal is much reduced or absent in samples of invasive cancer of the cervix. In order to identify the species responsible for the strong signal, we have used X-, S- and Q-band e.s.r. spectroscopy. The major signal that is detectable in ground-up samples of cervix preserved at -196 degrees C has features consistent with the presence of a peroxy free radical. Good agreement with the experimental findings was obtained by computer simulation, using values for the g-tensor of gx = 2.002, gy = 2.005 and gz = 2.036. The peroxy radical is produced on grinding the normal cervix samples to a powder under liquid N2, and appears to be formed by modification of a pre-existing oxygen-containing complex. Control experiments eliminated the possibility that the strong signals seen in frozen powders prepared from normal cervix were artefacts only of the grinding procedure. Experiments with rats in vivo and with cervix samples in vitro are consistent with the conclusion that the peroxy radical is formed by disturbing the cyclo-oxygenase system that is involved in prostaglandin synthesis.     

Expression of HOX homeogenes in human neuroblastoma cell culture lines

Mammalian genes containing a class-I homeobox (HOX genes) are highly expressed in the embryonic nervous system. As a first step towards the molecular analysis of the role these genes play in neural cells, we studied the expression of four human HOX genes in five neuroblastoma (NB) cell lines - SK-N-BE, CHP-134, IMR-32, SK-N-SH and LAN-1 - during the process of differentiation induced by treatment with retinoic acid (RA). The four genes, HOX1D, 2F, 3E and 4B, located at corresponding positions in the four HOX loci, share a high degree of sequence similarity with the Drosophila Deformed homeotic gene and constitute a homology group, group 10. One of these genes, HOX1D, is not expressed in the cells used, whereas the other three are highly expressed in untreated and RA-induced NB cells, even though the expression pattern in the various lines is slightly different for the three genes. Our analysis reveals a complex and specific expression pattern in these lines, paving the way to an identification of different NB-cell populations by means of specific HOX gene expression schemes. On the other hand, in every line studied, morphological maturation toward a neuronal differentiated phenotype appears to be associated with increased HOX gene expression.     

A hemagglutinin specific for sialic acids in a rat brain synaptic vesicle-enriched fraction

A hemagglutinating activity was detected in a synaptic vesicle-enriched fraction prepared from adult rat brain, using trypsinized glutaraldehyde-fixed rabbit erythrocytes. The specific activity of the fraction, in two series of experiments, was 7.5 and 16-fold higher than in the other subcellular fractions. The activity was absent from the synaptosome cytosol. In a study using twenty-five different carbohydrates and glycoproteins, best inhibitors were N-acetylneuraminic acid and N-glycolylneuraminic acid, together with bovine submaxillary mucin and a glycopeptide fraction prepared from rabbit erythrocyte membranes. The activity was thermolabile and very sensitive to proteolytic enzymes (but insensitive to neuraminidase) indicating that a protein (agglutinin) is responsible for the activity. Experiments using detergents and high ionic strength showed that the agglutinin is tightly bound to membranes, inactivated by the so-called non denaturing detergents, and stable in diluted sodium dodecyl sulphate. Hypotheses are discussed on the possible function of the agglutinin.     

Regulation of thromboxane A2 biosynthesis in platelet-free human monocytes and the possible role of polypeptide growth factor(s) in the induction of cyclooxygenase system

It has previously been shown that platelet-free human monocytes, when properly incubated in the presence of animal and human sera, became capable of producing large amounts of thromboxane A2 and prostaglandin E2. The characteristics of these processes are reported here. Prostaglandin biosynthesis was time and cell concentration dependent; 24 h of incubation at 37 degrees C and 0.5 X 10(6) cells per ml medium were found to give the most reproducible results. Human monocytes produced thromboxane A2 and prostaglandin E2 in a typical ratio which ranged from 2.0 to 5.0 (28 experiments). Animal and human sera were similarly effective, while serum obtained from platelet-free blood was much less active. The activity of all sera tested was stable to heating (100 degrees C for 2-10 min) and extreme pH values (pH 2 and 11). It was unstable when the serum was heated at pH 11 and after 2-mercaptoethanol treatment. These observations prompted us to check the effect of polypeptide growth factors having properties similar to those reported above, such as platelet-derived growth factor, fibroblast growth factor, epidermal growth factor as well as insulin and transferrin. None of these, alone or in various combinations, was capable of eliciting a stimulation comparable with that of serum. Stimulation due to sera was, as expected, dose dependently inhibited by acetylsalicylic acid and more efficiently by indomethacin; unexpectedly it was also inhibited by protein synthesis inhibitors such as actinomycin D and cycloheximide in conditions under which no toxic effect of the drugs was evident. On the basis of these results we conclude that: (a) polypeptide growth factor(s) with a molecular weight at least 30 000 (as judged by Amicon ultrafiltration) is involved in the regulation of prostaglandin biosynthesis); (b) such a factor(s) acts by inducing rather than by activating the cyclooxygenase system.     

Fragments of human γG immunoglobulins produced by a porcine pancreatic esterase

The effect of a porcine pancreatic esteroproteolytic enzyme on human IgG has been described. A sequential breakdown of the molecule occurs. The first cleavage results in the formation of an F′c fragment together with an F(ab)₂ fragment. A subsequent proteolysis of the F(ab)₂ fragment liberates two Fab fragments. Each fragment has been characterized by its antigenic properties, molecular weight, and sulfhydryl content.     

Effect of 17β-estradiol on calcium response to phytohaemagglutinin in human lymphocytes

Pre-treatment of human lymphocytes with 17-estradiol diminishes the increase in concentration of cytosolic free calcium after stimulation with phytohaemagglutinin. The effect is dependent on 17-estradiol concentration and on the preincubation time. The effect is not due to an interaction between 17-estradiol and phytohaemagglutinin, but appears to be a consequence of the binding of the hormone to the cell surface. The effect is specific for 17-estradiol, since the isomer and other steroid hormones (progesterone, testosterone, diethylstilbestrol and 5-androstan), have no effect. Since the effect of the 17-estradiol can be suppressed by treatment of lymphocytes with ouabain, it appears that the effect of estradiol on the rise of cytosolic calcium induced by phytohaemagglutinin is mediated by the (Na, K)-ATPase.