PubMed Health⌕ Search

Biomedical subjects

C Prevot

Publications and source records attributed to C Prevot.

13 recordsLinked to original sources
PubMed2001

Subcritical wet oxidation of municipal sewage sludge: comparison of batch and continuous experiments.

Wet oxidation in subcritical conditions is a new alternative to usual routes for sewage sludge treatment and it complies with environmental standards. The paper presents tests carried out on a batch reactor and on a continuous pilot unit, treating municipal sewage sludge. A method is proposed that shows that the oxidation efficiency in a continuous reactor can only be easily predicted from the residence time distribution and batch tests results. Nevertheless, a partial settling of the solid residue in the continuous bubble column reactor is evident, and it increases the solid residence time and then decreases its organic content with respect to a similar batch test. In addition, these results highlight the considerable influence of temperature in the oxidation reactor and of the type of sewage sludge which is treated. At temperatures around 240 degrees C, foaming can seriously impair the operation of the continuous reactor, because of the presence of non-degraded fatty compounds and surfactants. Moreover, the COD reduction is limited to 70%. On the contrary, at 300 degrees C, COD removal efficiency greater than 80% is achieved without any catalyst additive and, in addition, only highly biodegradable compounds remain in the oxidised liquor.

Fats↗
PubMed1992

Effect of social class and nutrient intake on height and plasma insulin-like growth factor in Andean Equadorian children.

The purpose of this study was to assess the validity of insulin-like growth factor (IGFI) determination as an index of nutritional status and growth in Equadorian schoolboys. Plasma IGFI was measured in 144 healthy boys, 9 years old, who were classified by their social class in four groups: 1 (n = 29); 2 (n = 49); 3 (n = 28); 4 (n = 8). Children in groups 1 and 2, of the lower socio-economic class, had significantly reduced caloric and protein intakes compared to children in groups 3 and 4 (P less than 0.01). Mean heights were significantly lower in groups 1 and 2 (P less than 0.001 and less than 0.05, respectively). The mean plasma IGFI in group 1 was 561 +/- 64 mU/ml and significantly lower than that in groups 2-4 (872 +/- 75, 986 +/- 94, and 1238 +/- 190 mU/ml in groups 2, 3 and 4, respectively) (P less than 0.01). The effect of caloric and nitrogen supplementation was studied in 36 children taken from groups 1 and 2 combined, and divided into three subgroups; they were given (1) an animal protein supplement of 18 g/day with 860 kcal/day (n = 12), (2) a vegetable protein supplement of 17.8 g/day based on a traditional Andean food with 862 kcal/day (n = 12), and (3) a placebo (n = 12). The IGFI levels increased significantly after 7 and 14 days in both subgroups 1 and 2. These results demonstrate that plasma IGFI reflects the nutritional status and responds to a short-term diet supplementation. It may provide a reliable means of assessing the effect of nutritional programs intended to improve the growth of children in underdeveloped countries.

Body Height↗
PubMed1991

Idiopathic central precocious puberty in girls as a model of the effect of plasma estradiol level on growth, skeletal maturation and plasma insulin-like growth factor I.

Girls suffering from idiopathic central precocious puberty (CPP) may have different levels of estrogenic activity. This study was performed to evaluate the relationship between the estrogenic activity and the hypothalamopituitary activation and the effect of various plasma estradiol (E2) levels on growth, skeletal maturation and plasma insulin-like growth factor I (IGF-I). Fifty-eight girls with CPP were divided into 2 groups: group I with E2 less than 25 pg/ml (13 +/- 1 pg/ml, mean +/- SEM, n = 26) and group II with E2 greater than or equal to 25 pg/ml (52 +/- 3 pg/ml, n = 32). The mean ages at onset and at evaluation were lower in group I (5.9 +/- 0.4 and 6.8 +/- 0.4 years) than in group II (6.8 +/- 0.3 and 8.1 +/- 0.2 years, p less than 0.01), but the durations since onset (greater than 0.5 and less than 2 years) in the two groups were similar. The mean peak luteinizing hormone/follicle-stimulating hormone (LH/FSH) ratios were lower in group I (0.8 +/- 0.2) than in group II (1.7 +/- 0.2, p less than 0.001) and correlated with E2 (r = 0.41, p less than 0.01). The mean height gains during the year preceding the initial evaluation were similar in the two groups (8.7 +/- 0.5 vs. 9.2 +/- 0.4 cm). They were independent of the plasma E2 level. Conversely, the mean plasma IGF-I values were lower in group I (2.4 +/- 0.3 U/ml) than in group II (4.2 +/- 0.6 U/ml, p less than 0.01) and correlated with E2 (r = 0.52, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Bone Development↗
PubMed1989

Precocious puberty in girls: early diagnosis of a slowly progressing variant.

An attempt was made to identify the less severe cases of precocious puberty and to describe their natural course. A group of 17 girls with precocious puberty and a bone age advance over chronological age of less than two years (group 1) was compared with a group of 19 patients with severe precocious puberty and bone age advance of two years or more (group 2). Mean (SEM) plasma oestradiol concentrations were 82 (30) pmol/l and 164 (21) pmol/l (p less than 0.05), vaginal maturation indexes were 16 (5) and 41 (4), and plasma somatomedin C concentrations were 1.0 (0.2) U/ml (n = 8) and 2.1 (0.3) U/ml (n = 16) in groups 1 and 2, respectively. The time between onset and diagnosis of secondary sexual characteristics was about one year in both groups. After two years' follow up the untreated patients in group 1 had maintained their predicted final height. These changes were in contrast to those observed at first examination in patients in group 2 who had a mean (SD) predicted final height of -1.3 (0.2) and a mean bone age advance of 3.0 (0.2) years. These data show that bone age advance to chronological age, and plasma somatomedin C concentrations measured at initial evaluation are helpful in identifying less severe and potentially slow progressing forms of central precocious puberty.

Age Determination by Skeleton↗
PubMed1989

A prospective study of the development of growth hormone deficiency in children given cranial irradiation, and its relation to statural growth.

Although GH deficiency (GHD) is the most frequent hormonal abnormality that occurs after cranial radiation, the natural course of this complication and its relationship to growth in children are not known. Therefore, we undertook a 2-yr prospective study of 16 children, aged 1.7-15 yr at the time of treatment, who received cranial [31-42 Gy (1 Gy = 100 rads)] and spinal radiation for medulloblastoma or ependymoma (group I). Their growth was compared to that of 11 children given similar doses of cranial radiation only (group II). The mean plasma GH response to arginine-insulin test (AITT) was 9.1 +/- 1.5 (+/- SE) micrograms/L in group I and 8.5 +/- 1.8 micrograms/L in group II (P = NS). After 2 yr, 16 of the 27 children had a peak plasma GH value below 8 micrograms/L after AITT, and 10 children had a peak response less than 5 micrograms/L. In addition, in group I, AITT and sleep-related GH secretion were compared; at the 2 yr follow-up only 3 of 13 children had discrepant results. At the 2 yr follow-up children treated by cranial and spinal radiation had a mean height of -1.46 +/- 0.40 SD below the normal mean. In contrast, the children given only cranial radiation had a mean height of -0.15 +/- 0.18 SD; P less than 0.02. Therefore, most of the growth retardation appeared to be due to lack of spinal growth. GHD is thus an early complication of cranial radiation in these children, and no significant growth retardation can be attributed to GHD during the first 2 yr. These data contribute to the organization of follow-up in irradiated children in order to decide when human GH treatment is necessary.

Adolescent↗
PubMed1988

[Effect of growth hormone on the differentiation of chondrocytes from prepuberal rabbits in serum-free culture and on the radioimmunologic activity of Sm-C/IGF1 measured in the culture medium].

This study concerns the immunoreactive somatomedin C secretion by prepubertal rabbit epiphyseal chondrocytes cultured in a defined serum-free medium. In such culture conditions, chondrocytes mainly synthesized Type II collagen (80% of total collagen) during 10 days. A small amount of Type I collagen was also found with a significant (p less than 0.05) higher level during the period of cell multiplication (6.4 +/- 1.5%) than when cells reached confluency (0.9 +/- 0.2%). During the 10 days of culture without serum and without hormone added, a Sm-C/IGF1 activity was measured by RIA at a mean level of 30 +/- 5 mU/ml/10 micrograms DNA. This value was significantly higher (p less than 0.001) than in the medium not incubated with the cells (1.7 +/- 0.9 mU/ml). When hGH was added to the culture medium during the period of cell division, the level of Sm-C/IGF1 activity was significantly elevated at 39 +/- 4 mU/ml/10 micrograms DNA (p less than 0.05) and at 55 +/- 3 mU/ml/10 micrograms DNA (p less than 0.001) with 50 ng/ml and 100 ng/ml hGH concentrations respectively. On the contrary, no difference was observed at confluency in treated and non treated cells.

Animals↗
PubMed1987

Somatomedin-C and growth in children with precocious puberty: a study of the effect of the level of growth hormone secretion.

This study was undertaken to investigate the role of GH secretion in the pubertal increase in plasma somatomedin-C (Sm-C) concentrations and its relation to growth in children with true precocious puberty (PP) and normal or deficient GH secretion. We studied 37 children (9 boys and 28 girls), divided into 3 groups according to their pubertal stages and their peak stimulated plasma GH concentration. Group I (n = 20) contained patients with PP and normal GH secretion. In group II (n = 8), PP was accompanied by GH deficiency. Group III (n = 9) patients were GH deficient and prepubertal. The mean plasma Sm-C (RIA) levels in groups I and II were 2.01 +/- 0.17 (+/- SEM) and 0.59 +/- 0.21 U/mL, respectively (P less than 0.001), and it was 0.09 +/- 0.01 U/mL in group III (P less than 0.001 compared to group II). The higher mean plasma Sm-C level in group II compared to that in group III could be related to a significantly higher GH response to arginine-insulin stimulation (P less than 0.02), although this value was in the hypopituitary range. The mean growth rate in group II (6.8 +/- 0.9 cm/yr) was also much higher than the rate in group III (1.9 +/- 0.5 cm/yr; P less than 0.001) and only slightly lower than that in group I (90 +/- 0.8 cm/yr; P less than 0.05). These data indicate that plasma Sm-C values are closely correlated with even small changes in GH secretion. The observed growth rates could, in general, be linked to plasma GH and Sm-C levels, as modulated by sex steroids, in these patients with precocious puberty.

Adolescent↗
PubMed1987

Phenotypic evolution of CTL B-lines in vitro.

This study demonstrates that cytolytic T-cell lines exhibit progressive in-vitro modifications of their phenotype and of their growth behaviour and may use different pathways for their multiplication. Comparing three established cell lines, we firstly demonstrated that the expression of LFA-I is stable but the Lyt 2, 3 is rapidly lost. In this case, a high lectin-dependent cytotoxicity appears. Secondly, we demonstrated that two of the cell lines used the interleukin 2-interleukin 2 receptors (IL-2-IL-2R) binding pathway. Two different monoclonal antibodies showed that the IL-2 receptors distribution does not correlate with the number of functional sites which determines the IL-2 requirement. In contrast, the third cell line, although bearing high levels of IL-2 receptors, grows without the addition of IL-2; this cell growth is not inhibited by anti-IL-2 receptors monoclonal antibodies. Thirdly, it appears that the new property of IL-2 independence is associated with acquisition of the simultaneous capacity to induce tumour grafts in nude mice. As it has been recently reported that cytolytic T-lymphocytes against tumour cells could be promising immunotherapeutic agents, the spontaneous malignant transformation of such CTL lines should be taken into account before using them for adoptive immunotherapeutic purposes.

Animals↗
PubMed1986

Growth, growth hormone secretion and somatomedin C after cranial irradiation for acute lymphoblastic leukemia.

In a large group of 74 patients irradiated with 2400 rad for acute lymphoblastic leukemia an unusually high frequency of complete GH deficiency was observed (40%). Only 11 out of 46 prepubertal children had growth retardation and seven children received hGH treatment. On the contrary 11 other prepubertal cases had normal growth rates in spite of lack of response to AITT. Plasma SmC values were correlated with growth rates but were discrepant with GH responses to AITT in some cases. Because of this high frequency of GH dysregulation further growth at time of puberty should be carefully documented.

Body Height↗
PubMed1980

Somatomedin activity and growth hormone secretion. I. Changes related to body weight in anorexia nervosa.

Anorexia nervosa in childhood and adolescence, associated with impaired growth can be considered as a form of chronic malnutrition. Twelve patients aged 11 to 17 years were investigated. In spite of increased GH secretion, plasma somatomedin activities were diminished in 8 cases. Plasma T4, T3 and arginine stimulated insulin secretion were also decreased. In six patients who gained weight a significant negative correlation was found between weight deficit and plasma somatomedin activity. Prolonged administration of growth hormone in one case did not stimulate the generation of somatomedin activity. Nutrition and increased insulin secretion could plan a role in changes observed during recovery.

Adolescent↗
PubMed1980

[Somatomedin activity and growth hormone secretion in children with idiopathic growth retardation (author's transl)].

Somatomedin activity, as estimated by the porcine bioassay and GH response to stimulation were compared in prepubertal children with severe growth retardation and lack of evidence of pituitary dysfunction. Somatomedin activity was strongly correlated with growth rate. A group of patients had a low somatomedin activity in contrast with normal GH responsiveness. This appears to be a rather frequent situation and deserves further evaluation of the somatomedin system and a more critical approach of GH secretion.

Adolescent↗