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C Simon

Publications and source records attributed to C Simon.

At least 289 records · Page 16Linked to original sources
PubMed1983

[Apoproteins A1 and B as markers of the severity of cirrhosis].

Since apolipoproteins A1 and B (Apo A1 and Apo B), which are the quantitatively predominant fractions of plasma lipoproteins, are synthetized and/or metabolized in the liver, their variations could represent a significant prognostic factor in patients with cirrhosis. In order to test this theory, the concentrations of Apo A1 and Apo B were measured in 43 patients with confirmed cirrhosis and were found to be reduced. These changes correlated with a number of biochemical tests measuring hepatic function and indicating severe cirrhosis, as well as with a clinico-biological severity index based on these biochemical tests and on the importance of clinical complications during the course of the disease. It is concluded that Apo 1 and Apo B determinations constitute a valuable index of liver synthetizing function.

Apolipoprotein A-I↗
PubMed1983

[Quantitative evaluation of hormonal extraction performed by continuous plasma exchange in euthyroid patients. Application to the treatment of severe hyperthyroidism].

Plasma exchanges (PE) have been successfully used in the treatment of thyroid storm. The dramatic results obtained (as in the case reported here) have prompted the authors to evaluate the effects of PE on plasma thyroid hormone (T4, T3 and unbound T4) levels and thyroxine-binding globulin (TBG) levels in 5 euthyroid patients. PE of one blood volume consistently produced a significant decrease in T4, T3 and TBG levels without changes in unbound T4 or TSH. Hormone extraction was proportional to the volume of blood removed and correlated with the amount of TBG extracted. Compared with the estimated total plasma content, the percentage of unbound T4 extracted was superior to that of total T4, which suggests release of free hormones from the intracellular compartment. Repeated PE in the same patient resulted in a transient decrease in T4 without changes in TSH. These results indicate that PE constitutes a fast, simple and effective means of removing thyroid hormones in all emergencies related to thyrotoxicosis. The fact that TSH levels remain stable after PE shows that the thyroid balance in euthyroid subjects is unaffected by this method.

Evaluation Studies as Topic↗
PubMed1983

Modulations of neurofilament axonal transport during the development of rabbit retinal ganglion cells.

We have compared the polypeptides undergoing axonal transport in the retinal ganglion cells of neonatal and adult rabbits, and have observed the following: (1) Representative polypeptides of five different adult transport groups are axonally transported from the time of birth. (2) Polypeptides of group IV (a group that includes actin and myosin) are transported two-fold more rapidly in neonates than in adults. (3) Two polypeptides, M (145K) and L (73K) that are components of neurofilaments and move with the fifth, slowest group of transported proteins, are transported approximately eight-fold more rapidly in neonatal rabbits than in adults. (4) H, a third group V polypeptide, that serves to crosslink neurofilaments, was not detected in the rabbit optic nerve until 12 days after birth. We consider the possibility that the late induction of the crosslinker precipitates a cytoskeletal "phase transition" that may be responsible for the developmental alterations in apparent transport velocities, and may have additional consequences for neuronal development.

Aging↗
PubMed1983

Thyroid lysosomes: the stability of the lysosomal membrane.

To determine the integrity of lysosomes during their isolation from rat thyroid glands and their subsequent incubation at 37 degrees C, the sedimentability of lysosomal acid phosphatase and thyroglobulin (amount of undisrupted lysosomes) and the latency of sedimentable acid phosphatase (permeability of undisrupted lysosomes) were measured concomitantly. The following results were obtained: (a) During isolation of lysosomes in 0.25 M sucrose medium, mild homogenization of thyroid tissue or cholesterol addition did not modify the amount of undisrupted lysosomes but reduced their permeability. Homogenization in 0.5 M sucrose decreased both the amount and the permeability of undisrupted lysosomes. It also reduced their content of recently iodinated thyroglobulin (Tg). Cholesterol addition had no effect in 0.5 M sucrose medium. (b) During incubations at 37 degrees C of lysosomes, the amount of undisrupted lysosomes decreased progressively while their permeability increased. According to the incubation pH, the permeability of lysosomes prepared in 0.25 M sucrose was either more (pH 8) or less (pH 6) extensively increased than that of lysosomes prepared in 0.5 M sucrose. From these results, we concluded: (a) that isolation and incubation of the thyroid lysosomal fraction induce increased permeability of lysosomes prior to their complete disruption: (b) that recently formed lysosomes (high content of recently iodinated Tg) and aged lysosomes (low content of recently iodinated Tg) differ significantly. Recently formed lysosomes are more permeable, are stabilized by cholesterol and are more extensively disrupted in 0.5 M sucrose medium. During incubations, the permeabilities of these two classes of lysosomes are also differently affected by external pH.

Acid Phosphatase↗
PubMed1983

Intralysosomal hydrolysis of thyroglobulin. II. Different fates of poorly and fully iodinated Tg and specific activation by TSH of the degradation of fully iodinated Tg.

Degradations of recently (1 h) iodinated thyroglobulin (Tg) and of Tg iodinated for 48 h (fully iodinated molecule) inside thyroid phagolysosomes have been measured in vitro, at different pH, in basal (lysosomes from normal rats) and stimulated (lysosomes from TSH-treated rats) conditions. In basal conditions, recently iodinated Tg was shown to be preferentially degraded at pH 5 but not at pH 8. Mercaptoethanol (ME) was found to preferentially stimulate the degradation of 48 h-iodinated Tg at pH 5 but not at pH 8. In stimulated conditions and in the presence of ME, no preferential hydrolysis of recently iodinated Tg was observed, whatever the pH. Since the degradation of Tg and its stimulation by ME are known to depend on the mean iodine content of the molecule, it was concluded that: 1) the recently iodinated Tg population contains both poorly and fully iodinated molecules, the degradations of which are faster or similar to that of 48 h-iodinated Tg, respectively, 2) among thyroid phagolysosomes, only those which exhibit a pH-dependent proteolytic activity contain poorly iodinated molecules while others, which are functional at either pH, contain solely fully iodinated molecules (1 and 48 h labelled), 3) reduction of the disulphide bridges of fully iodinated Tg, mediated by ME and probably a lysosomal transhydrogenase, is a prerequisite for its optimal degradation by lysosomal proteinases, 4) in addition, TSH, which preferentially stimulates the degradation of fully iodinated Tg, was concluded to interfere directly upon the intralysosomal hydrolytic process, independently of its effect upon Tg endocytosis. This effect of TSH, similar and additive to that of ME suggests that the hormone might activate a lysosomal transhydrogenase.

Animals↗
PubMed1983

Intralysosomal hydrolysis of thyroglobulin. I. Modulation by lysosomal membrane permeability and exogenous factors.

Intralysosomal hydrolysis of endogenous (125I in vivo labelled) thyroglobulin (Tg) inside thyroid phagolysosomes and its modulation by exogenous factors (external pH, activators and inhibitors of lysosomal proteinases) were studied during in vitro incubations. Tg degradation was followed as the time-dependent increase in TCA-soluble radioiodine (free iodoaminoacids). The results demonstrate that this hydrolysis is only partially pH-dependent, one component being abolished by pH 8 and a cathepsin B inhibitor (zinc) whereas the residual activity was pH-independent and insensitive to zinc. It would seem therefore that the total thyroid phagolysosome population contains lysosomes permeable to both incubation buffer and zinc and lysosomes impermeable to these compounds. Both classes are operational (degrade Tg) at acidic or neutral pHs, while only impermeable organelles function when incubated at pH 8. These impermeable lysosomes have an acidic internal pH (about pH 5) and resist alkalinization very efficiently due to the high impermeability of their membranes. Additional experiments are in progress to determine the physiological significance of these two classes of lysosomes which might be related to a functional maturation of thyroid phagolysosomes.

Acid Phosphatase↗
PubMed1982

[Serum beta 2 microglobulin assay in diabetes mellitus (author's transl)].

Beta 2 microglobulin (beta 2m) is continuously produced and subsequently almost exclusively eliminated by glomerular filtration (GRF). There is a strong correlation between serum beta 2m and serum creatinine concentrations. Beta 2m assay however seems to enhance diagnostic accuracy of minor decreases in GRF. Serum beta 2m concentrations were assayed in 193 consecutive patients with diabetes mellitus. They correlated well with serum creatinine. Supranormal serum beta 2m concentrations (greater than 2.4 micrograms/lm) were found in 15.5% of patients with normal serum creatinine. Increase in beta 2 m/was related to poor metabolic control of diabetes and correlated positively with glycosylated hemoglobin concentrations. Serum beta 2m concentrations were also related to the duration of recognized diabetes. Serum beta 2m assay allows early detection of GRF disorders in patients with diabetes mellitus. Such disorders may be partly reversible once metabolic control is improved.

Adolescent↗
PubMed1982

[Retroinhibition of thyroid iodide active transport in rats, after a long iodine deficient diet followed by a normal iodine diet].

Rats were submitted to an iodine deficient diet during 6 months. At the end of this treatment, normal iodine diet was given to the animals during 16 days. For the first two days of iodine refeeding, thyroidal iodide was strongly stored, which is explained by a very stimulated iodide pump and by an iodination blockade. After this latency, the thyroidal iodide promptly decreased whereas iodide pump was always activated, and iodination still inhibited. A retroinhibition by thyroidal iodide on its active transport is postulated.

Animals↗
PubMed1982

[Occurrence and diagnosis of Chlamydia trachomatis infections in newborns and young infants (author's transl)].

Chlamydia trachomatis was assayed using McCoy cell culture on vaginal swabs from pregnant women and on conjunctival and nasopharyngeal swabs from newborns. C. trachomatis was found in 23 of 168 pregnant women (8%) and in 15 of 298 newborns (5%). Six newborns developed a typical inclusion conjunctivitis, whereas three infants developed pneumonia caused by C. trachomatis. Of a total of 50 children with conjunctivitis, C. trachomatis was found in six of 22 newborns, in four of 22 infants (2-3 months old) and in none of the older infants and children. Specific antibodies in serum could be demonstrated in most patients by the microimmunofluorescence technique, whereas antibodies against C. trachomatis were only found in a small percentage of the healthy children of various ages. Recommendations are given for the diagnosis of infections caused by C. trachomatis in newborns and infants.

Adolescent↗
PubMed1982

Thyroid iodide compartments and their implication in the rat thyroid iodine organification.

To estimate the relative participation of transported and intrathyroidally generated iodide (internal iodide) in the iodination of newly synthesized and preexisting thyroglobulin (Tg) in the rat thyroid, the specific radioactivities (SRAs) of thyroid iodide, Tg, lysosomal iodine, and plasma hormones were followed for 92 h after radioactive iodide injection in intact or hypophysectomized rats. In control rats, the SRA of Tg and lysosomal iodine reached a maximum at 12 h. However, the SRA of lysosomal iodide was always smaller than that of Tg. In contrast, the SRA of hormonal iodide attained a maximum at 48 h. Thus, newly labeled iodine is endocytosed and mixed inside the lysosomes with older previously iodinated molecules; hormone secretion is mainly due to old labeled iodine (i.e. iodine with a high SRA from 48-96 h). These results are consistent with the presence of least two Tg compartments, with different turnover rates and hormone contents. On the other hand, in hypophysectomized rats, the SRA of Tg, lysosomes, and hormones showed only one maximum, at 24 h. Furthermore, the SRAs of Tg and lysosomes were similar at each time interval. It is inferred that in such rats, the old labeled iodine compartment is strongly reduced, and that inside the lysosomes, newly labeled iodine is predominant. Since in hypophysectomized rats, the recycling of iodide is abolished, it is concluded that in normal rats: 1) transported iodide is organified mainly by direct iodination of newly synthesized Tg, independently of TSH, and 2) internal iodide is organified mainly by delayed iodination of preexisting Tg, this process being TSH dependent.

Animals↗