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Biomedical subjects

L Colobert

Publications and source records attributed to L Colobert.

At least 19 recordsLinked to original sources
PubMed1979

[Adenylate cyclase activation and its effects on intracellular cAMP in infected KB cells during trypsin-induced infectious Sendaï virus production (author's transl)].

KB cells infected by Sendaï virus can produce infectious virus if they are trypsinated twice over 24 h. Adenylate cyclase activity in infected KB cells is higher and more strongly activated by trypsin than that of control cells, but intracellular concentration of cAMP is the same, except during a short time after trypsinations, especially after the second trypsination which causes infectious virus production. During this short time, intracellular cAMP is slightly higher in infected cells. This miseffect of adenylate cyclase activation on intracellular cAMP concentrations might be related to an increased cell permeability caused by trypsin.

Adenylyl Cyclases↗
PubMed1978

[alpha-Amylase activity in lysosomes of Aspergillus oryzae (author's transl)].

The alpha-amylase of mycelial cells of Aspergillus oryzae exists in a particular form in 8000 g pellet. The lysosomal localization of acid phosphatase is confirmed by electron microscopy. The purification of lysosomes by discontinuous gradient of sucrose in D2O shows that alpha-amylase activity is bound to these particles.

Acid Phosphatase↗
PubMed1978

[The humoral immune response in recent pulmonary tuberculosis (author's transl)].

The average serum concentration of immunoglobulins, alpha-1-antitrypsin, haptoglobin and alpha-2-macroglobulin, calculated in 45 adults with pulmonary tuberculosis increased in a variable way for each of the six parameters studied. Tuberculosis does not induce new correlations between the parameters but modifies the intensity of existing links.

Adult↗
PubMed1977

[Production of interferon and alpha 2-macroglobulin involvement in immune response during human viral hepatitis A (author's transl)].

In viral hepatitis A, we could distinguish between monophasic and polyphasic forms. Monophasic and polyphasic hepatitis A induce the production of plasma interferon. Interferon level, elevated as early as the first days following the appearance of clinical signs, decreases and reaches a minimum value on the seventh day. A new rise of interferon is characterized by a maximum level on the twelfth day and a minimum level on the thirtieth. Beyond the first month we could still detect the presence of interferon. In the two forms of hepatitis, a complement system is activated both by classical and alternate pathways. IgM levels increase early, IgA levels remain unchanged. On the other hand, IgG levels, only slightly elevated in monophasic hepatitis A, are highly increased in polyphasic hepatitis A beyond the first month. Alpha 2-macroglobulin reaches levels above normal during convalescence in monophasic hepatitis A; on the contrary, in polyphasic hepatitis A, alpha 2-macroglobulin levles are above normal as early as the thirty first days of illness and remain above normal for several months. Elevated levels in alpha 2-macroglobulin may inhibit cellular immunity which is accountable for immunological injury of virus infected hepatocytes. We wonder whether this earlier increase in alpha 2-macroglobulin is responsible for the lasting character of viral infection observed in polyphasic hepatitis A.

Hepatitis, Viral, Human↗
PubMed1977

[Optimal conditions of alpha-amylase production by Aspergillus oryzae in liquid media].

The alpha-amylase secretion in a mineral culture medium containing starch and glucose follow the lysis of mycelium. This lysis seems to result from the hydrolysing action of dextranase and levulanase on cell wall. Cell lysis and amylase secretion are greatly enhanced by pH elevation of culture medium (optimal pH 8,8). In such conditions of production the amylase is not stable but can be stabilized by addition of starch. A method is described using pH and starch content modifications, which allows to obtain an amylase production three times greater than in standard culture medium.

Amylases↗
PubMed1977

[Study of various serum proteins in lung cancer. Immunoglobulins A, G, M, haptoglobin, alpha-1-antitrypsin, alpha-2-macroglobulin].

A statistical study of the plasma concentration of immunoglobulin, alpha-1-antitrypsin, haptoglobin, and alpha-2-macroglobulin in 153 patients with primary carcinoma of the lung showed a strong increase in alpha-1-antitrypsin, haptoglobin and A and C immunoglobulins, whilst alpha-2-macroglobulin increases very moderately, and IgM does not vary. The relationships between variables are also modified, thus there appears a correlation between IgA and IgG to the detriment of the IgG/IgM relationship. Furthermore the coefficient of the correlation IgG/alpha-2-macroblobulin is lower in cancer patients.

Female↗
PubMed1976

[Enzymatic characteristics of the guanylate cyclase of KB cells: their change as a function of the development of the cultures].

We have localized 71% of the guanylate cyclase activity in the (G X 105,000) supernatent fraction of broken KB cells. The reaction follows Michaelis-Menten kinetics, the apparent Km for GTP is 0,5 mM, as long as GTP is lower than a limited concentration, then activity is inhibited. The ion Mn++ is an absolutely required activator, it does not change enzyme-substrate affinity. The enzyme shows several types of binding sites of Mn++. Guanylate cyclase, studied over a period of development of culture, shows, in KB cells without cell contact, an activity higher than that observed in confluent cells. This is not due to the fact of a change in enzyme-substrate affinity but to a modification of Mn++ influence.

Cell Adhesion↗
PubMed1975

[Enzymatic characteristics of the catalytic subunit of the protein kinase complex of human lymphocytes].

In earlier reports we have shown the existence in human lymphocytes homogenate, of a cyclic-AMP dependent protein-kinase activity. We demonstrate by affinity chromatography that two subunits display respectively cyclic-AMP binding and phosphorylating properties. Divalent cations such as Ca++, Mg++ or Mn++ are required for enzymatic activity. ATP which is an obligatory cosubstrate acts as an inhibitor when its concentration is higher than 10(-6)M.

Adenosine Triphosphate↗