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Biomedical subjects

G Biserte

Publications and source records attributed to G Biserte.

At least 19 recordsLinked to original sources
PubMed1979

Evidence for heterogeneous or incomplete immunoglobulins in oligoclonal CSF studied by electroimmunofixation.

10 oligoclonal CSF have been studied by electroimmunofixation techniques on Cellogel RS. The gammaglobulin bands are either homogeneous or heterogeneous. The heterogeneous bands migrate preferentially in the cathodic part of the gamma zone. The light chain type of many homogeneous bands is lambda. Some oligoclonal bands may be composed of free homogeneous light chains. The free lambda chains have a more anodic migration than the free kappa chains. Furthermore, our results suggest the presence of free heavy chains in some instances.

Humans↗
PubMed1979

Microheterogeneity of rat, mouse and human alpha1-fetoprotein as revealed by polyacrylamide gel electrophoresis and by crossed immuno-affino-electrophoresis with different lectins.

Polyacrylamide gel electrophoresis and crossed immuno-affino-electrophoresis with several free lectins have been used to characterize and to compare the molecular heterogeneity of rat, mouse and human alpha1-fetoproteins. Each alpha1-fetoprotein contains a variable number of electrophoretic variants depending on the gel porosity. In SDS electrophoresis, two molecular size populations are present in rat alpha1-fetoprotein (Mr = 74 000 and 72 000) and in mouse alpha1-fetoprotein (Mr = 73 000 and 72 000) but only one is observed in human alpha1-fetoprotein (Mr = 70 000). The crossed immuno-affino-electrophoresis patterns square with affinity chromatography results and reveal a marked and characteristic heterogeneity for the three alpha1-fetoprotein species with Concanavalin A, Ricinus communis and Lens culinaris lectins. No lectin-alpha-fetoprotein interaction is apparent with Ulex, Lotus and wheat germ lectins. Since similar patterns are obtained whether with purified alpha1-fetoprotein or with unfractionated fresh fetal sera, it is likely that this heterogeneity is not a consequence of artefactual molecular modifications arising during the purification procedure.

Animals↗
PubMed1979

Nickel sub-sulphide-induced leiomyosarcoma in rabbit white skeletal muscle: a light microscopical and ultrastructural study.

Nickel sub-sulphide-induced leiomyosarcomas in rabbit white skeletal muscle were studied by both light and electron microscopy. Two types of tumor cells, small spindle cells and elongated smooth muscle cells, are revealed by light microscopy. Nevertheless, their ultrastructure displays the same general feature. The most differentiated cells have abundant cytoplasmic filaments 7 nm in diameter, kept together in bundles by dense bodies. There also exist many 10 nm filaments and a large number of microtubules. The nuclei have prominent nucleoli with an extensive nucleolonema which form an irregular tridimensional network. Distinct fibrillar nuclear bodies were observed. Sometimes there exist desmosomes or gap junctions. The Golgi apparatus produces coated vesicles with secretory function. In the tumors were generally found the Ni3S2 implantations surrounded by a capsule, the major component of which were collagen fibers, degenerated nuclei and rod-like structures with a transverse periodicity of 15.5 nm. From these observations, several characteristics should be pointed out: 1) Many tumor cells contain large nucleoli and distinct intranuclear inclusions of undetermined nature. 2) The coated vesicles represent a secretory activity of the tumor cells; the coat material is probably used during the formation of cell membranes. Another possible function of coated vesicles could be the sequestering of calcium ions. 3) The rod-like structures in the Ni3S2-including capsule are not of Z-line material. 4) The tumoral stem myoblast in heart and skeletal muscle arise from mesenchymal cells.

Animals↗
PubMed1979

Developmental aspect of phenylalanine hydroxylase in the rat -- hormonal influences.

Interpretations of the development of phenylalanine hydroxylase (PAH) in rat liver have been controversial, and the mechanism of ontogenic changes have not yet been elucidated. Fetal PAH activity at a gestational age of 21 days appeared to reach 32% that of adult male level at birth. The in vivo effectiveness of fetal PAH activity was correlated with enhancement of blood tyrosine, while amino-transferase activity appeared only after birth. No sex difference was noted in weaning rats, whereas, in adult females, PAH activity was only 42% that of males. Investigating hormonal influences on liver PAH activity we noted no change of enzyme activity following hydrocortisone, ACTH and estradiol treatment. However, 4 days of testosterone treatment in weaning female rats increased PAH activity (X1.7). Therefore, testosterone could explain increased PAH activity in adult males.

Adrenalectomy↗
PubMed1979

[Partial characterization of 2 extracellular aminopeptidases (arylamidases) from the dermatophyte Keratinomyces ajelloi].

Two aminopeptidases AP1 and AP2 have been isolated from Keratinomyces ajelloi filtrates. The molecular weight is about 27 000 for AP1 and 23 000 for AP2. Both aminopeptidases present maximum activity at pH 9.35 but 50 p. 100 of maximum activity is observed between pH 7.5 and pH 8.5. Km values measured at pH 9.35 with L-leucine-p-nitroanilide as substrate are 0.38 X 10(-3) M for AP1 and 0.43 X 10(-3) M for AP2. kcat at the same pH are 63.6 sec.-1 for AP-1 and 62.8 sec-1 for AP2. Both aminopeptidases are inhibited by mercuric chloride, o-phenanthroline, dithiothreitol and 2-mercaptoethanol. Some of their characters make them similar to Streptomyces griseus pronase aminopeptidases.

Aminopeptidases↗
PubMed1979

Amino acid sequence of rat thymus histone H2B and identification of the in vitro phosphorylation sites.

The amino acid sequence of rat thymus histone obtained in highly purified form by preparative electrophoresis, was determined. This sequence is identical to the sequence of calf thymus histone H2B. The in vitro phosphorylation of the rat histone with a cyclic AMP-dependent protein kinase isolated from rat pancreas led to the identification of four sites of phosphorylation: two major ones, at serine residues 32 and 36, and two minor ones, specific of the rat protein kinase, at serine residues 87 and 91.

Amino Acid Sequence↗
PubMed1979

On the mechanism of the tetrahydropteridine cofactor oxidation in aerobic and H2O2-peroxydase media.

It is commonly postulated that the enzymatic hydroxylation of phenylalanine, tyrosine and tryptophan involves the concomitant oxidation of a tetrahydropteridinic cofactor to an unstable quinonoid product, converted to the initial compound under the catalytic action of dihydropteridine reductase. We now report UV, NMR, mass spectrum and spectroscopic studies of 2-amino-4-hydroxy-6,7-dimethyl-5, 6, 7, 8-tetrahydropteridine oxidation process either by atmospheric O2 or by the H2O2-peroxidase system. No quinonoid form was visualized and, moreover, the spectral characteristics of UV absorbance spectra, initially reported as specific for the quinonoid form, are related to other oxidation products whose formation is explained here.

Hydrogen Peroxide↗
PubMed1979

Cylindrical laminated bodies in nickel-subsulphide-induced rhabdomyosarcoma in rabbits.

The induction of rabbit rhabdomyosarcoma was obtained after intramuscular implantation of a large quantity of very pure nickel subsulphide, though until the present time the rabbit was considered refractory to Ni3S2 tumorigenesis. These tumors are similar to those induced in rats under the same conditions. Four different cell types were observed: small polygonal cells, small elongated cells, giant cells, and mature myofibers. Electron microscopy reveals a complete disorientation of myofibrils in mature myoblasts. Giant cells appear by pluripolar endomitosis and always contain myofibrillar structures, but M-lines and Z-lines are not present in these cells. Cylindrical laminated bodies were observed very often in all four cell types. They are formed of 4 nm fibrils arranged in crossed position in each lamella. Some of these paracrystalline structures were also observed in nuclei. The laminated bodies are considered to be abnormal formations of contractile proteins produced during tumoral myofibrillar differentiation.

Animals↗
PubMed1978

[Biochemical study of the glycosaminoglycan peptides obtained from osteoarthrotic and normal femoral heads (author's transl)].

Glycosaminoglycan peptides prepared by papain hydrolysis of different regions were obtained from osteoarthrotic and normal human femoral heads. Data obtained in these experiments show that in osteoarthrosis a decrease in keratan sulfate and an increase in chondroitin sulfate are observed. Since keratan sulfate appeared to play an important role in proteoglycan aggregation, we suggest that the keratan sulfate decrease is one of the factors involved in the cartilage disorder observed in patients suffering from osteoarthrosis.

Aged↗
PubMed1978

Ultrastructural investigation of NI3S2-induced rhabdomyosarcoma in Wistar rat: comparative study with emphasis on myofibrillar differentiation and ciliar formation.

Nickel-sulfid-induced rhabdomyosarcomas were studied by both light and electron microscopy. The successive stages differentiating tumor cells were described, and two differentiation types of rhabdomyoblasts could be observed 1) with the characteristic pattern of fetal differentiation--i.e., myofilament apparation before Z-line formation--and 2) with synthesis of these elements in the reverse order. An organized T-system is not evident. The sarcoplasmic reticulum is irregular and its cisternae often contain a granular substance or microcrystals. The only well-developed element of tumoral myofibrils is the Z-line; the other zones of sarcomeres are seldom clearly defined. Several unusual granular structures were observed. No virus particles were found. The formation of cilia appears only in interphase rhabdomyoblasts and has to be considered as aberrant and temporary formations from centrioles. They generally possess a "9 + 0" microtubular pattern, but often could be observed as rudimentary forms with a "7 + 2" microtubular arrangement. This case is another example demonstrating the relationship of cilia formation with cell division, especially after suppression of mitotic control. The histology and the electron microscopy results are discussed in relation to the differentiation pattern and the ultrastructural features of embryonic, regenerating and pathological muscle differentiating in vitro.

Animals↗
PubMed1978

Phenylalanine analogues as inhibitors of phenylalanine-hydroxylase from rat liver. New conclusions concerning kinetic behaviors of the enzyme.

The conversion of phenylalanine to tyrosine is catalysed by phenylalanine-hydroxylase. The substrate phenylalanine shows two effects: (1) allosteric transition at low phenylalanine concentrations, (2) excess substration inhibition. The molecular structure of phenylalanine-hydroxylase has not yet been elucidated. However, a tetrameric structure has been proposed. The Kinetic analysis with respect to substrate analogues suggest the existence of three types of sites on each protomer: (1) a catalytic site, (2) a non-competitive inhibitory site, (3) a positive cooperative site. Use of the enzyme's natural cofactor, tetrahydrobiopterin, has been emphasized to ensure good interpretation of the kinetic results of the phenylalanine-hydroxylase effectors.

Allosteric Site↗
PubMed1978

Primary structure of chicken erythrocyte histone H2A.

The complete amino acid sequence (128 residues) of the chicken erythrocyte histone H2A was deduced from the data provided by structural studies on the tryptic peptides from the maleylated histone and of the peptides obtained by thermolysin digestion of the native protein. The sequence of chicken histone H2A differs from the calf homologous histone by the deletion of one residue of histidine at position 123 or 124 and three conservative substitutions: a residue of serine replaces a residue of threonine at position 16, a residue of aspartic acid replaces a residue of glutamic acid at position 121 and a residue of alanine replaces a residue of glycine at position 128.

Amino Acid Sequence↗