PubMed Health⌕ Search

Biomedical subjects

J André

Publications and source records attributed to J André.

At least 19 recordsLinked to original sources
PubMed1992

The control by estradiol of pituitary tumor and cell growth is not correlated with that of kallikrein gene expression.

From an MtTF4 pituitary tumor we established new cell lines and tumors whose growth is sensitive (stimulation or inhibition) or insensitive to estradiol (Cancer Res., 1991, 50, 3786-3794). The main objective of the present work was to determine whether such a diversity of responses is correlated with the estradiol control of kallikrein gene expression. From kallikrein mRNA analyses and from kallikrein activity assays in conditioned medium it appears highly probable that the diversity of responses to estradiol of pituitary tumors and cell growth is not due to a differential regulation of kallikrein gene expression. In addition, prolactin gene expression and estrogen receptor mRNA have been studied to further characterize this experimental model.

Animals↗
PubMed1992

Possible involvement of transforming growth factor-beta in the inhibition of rat pituitary tumor growth by estradiol.

We have shown that growth of F4Z2 cells and F4Z2 tumors was stimulated by estradiol, that of MtTF4 and F4P tumors was inhibited and that of F4P cells remained insensitive. In the present work we explore the possible role of transforming growth factor-beta (TGF-beta) as a mediator of estradiol action in these pituitary tumors and cell lines. In vivo, estradiol treatment increased the concentration of TGF-beta 1 mRNAs in tumors whose growth was inhibited by estradiol (MtTF4 and F4P) but not in tumors whose growth was stimulated (F4Z2). F4Z2 and F4P cell lines also contained TGF-beta 1 transcripts. These cells and tumors differed by two points: the level of TGF-beta 1 transcript was higher in F4Z2 than in F4P cells while the opposite situation was observed in vivo and the concentration of TGF-beta 1 mRNA in cultured cells was insensitive to estradiol (1 or 100 x 10(-9) M). Moreover, the secretion of TGF-beta like activity assayed by two different methods was estradiol insensitive and the growth of both cell lines was dose-dependently inhibited by TGF-beta 1 (ED50:2 x 10(-11) M). Since estradiol increases TGF-beta 1 mRNA in the tumors MtTF4 and F4P whose growth is inhibited by estradiol and that TGF-beta 1 inhibits the proliferation of F4P cells it is proposed as a working hypothesis that TGF-beta 1 is one of the mediators of the inhibitory effect of estradiol in pituitary tumors. No data favor the hypothesis that estradiol stimulates pituitary tumor proliferation by decreasing TGF-beta production.

Animals↗
PubMed1992

Sex and age dependence of rat kidney sialidase.

Rat kidney sialidase levels have been reported to be markedly altered in pathological states such as diabetes. This was associated with a modification of sialic acid levels. Therefore, it was interesting to study the variations of kidney sialidase and sialyltransferase activities and sialic acid content according to sex and age. This was carried out from birth to 210 days of age. The substrates used were sialyl alpha(2-3)[3H]-lactitol for sialidase activity, asialofetuin and [14C]-CMPNeu5Ac for sialyltransferase activity. In males sialidase activity increased until 32 days then slightly declined. In females, the activity increased and leveled off at 135 days of age. Higher sialidase activity was observed in females than in males from 56 days of age. Gonadectomy had no effect on this activity. In both sexes, sialyltransferase activity decreased markedly with age. This activity was higher in females than in males, whereas sialic acid levels varied only moderately with age and were slightly higher in females.

Aging↗
PubMed1992

[Leprosy survey conducted in the Central African Republic from 1982 to 1985 among the Ba-Benzele Pygmies].

A leprosy survey was conducted from 1982 to 1985 among 2650 semi-sedentarized Pygmies in two camp-villages in the Central African Republic. Leprosy is endemic there, with an estimated prevalence rate of 1.05% and an annual detection rate of 0.2%. In view of its close relations with other neighbouring ethnic groups this Pygmy community can be considered as a target population the study of which provides indications on the transmission and typical course of leprosy in the region and also as a potential focus of contamination. However, the concurrent presence of endemic tuberculosis made it necessary during the survey to look for clinical associations of leprosy and tuberculosis in patients so that the standard multidrug treatment schedules comprising rifampicin could be adjusted accordingly.

Adolescent↗
PubMed1991

Nails in light and electron microscopy.

The study and the diagnosis of nail disorders benefit from examination under light and electron microscopes. The alterations occurring in the matrix, bed, and hyponychium are comparable to those observed in the skin. Architectural and cellular alterations--loss of the cell's regular alignment, changes in stain affinity, parakeratosis, and changes in the intercellular spaces--are observed in the nail plate and subungual keratin. The intensity and singularities of these lesions are usually sufficient to orient the diagnosis from examination of the keratin alone. This microscopic examination is of particular interest in dealing with mycoses because it can specify the type of invasion of the keratin and avoid false-positive or false-negative results on culturing. Electron microscopy allows easy differentiation of melanin and ferric pigments.

Humans↗
PubMed1990

[Lichen planus: etiopathogenesis].

Lichen planus could result from a succession of immunological events: stimulation of Langerhans cells and keratinocytes by foreign antigen--production of interleukin 1 (IL 1)--activation, attraction and multiplication of helper T lymphocytes--production of interferon gamma--appearance of intercellular adhesion molecule-1 (ICAM 1) and HLA DR Antigen on keratinocytes membranes, allowing adhesion of T lymphocytes to keratinocytes and subsequent destruction of the latter.

Antigens, CD↗
PubMed1990

[Hormonal control of gene expression].

Three main aspects are presented: the current knowledge of structure, function and regulation of the genes coding for mRNAs is first examined. The central role of specific protein-DNA and protein-protein interactions is outlined. The two mechanisms of the hormonal regulation of genome expression, are then investigated. Hydrophobic hormones (steroid or thyroid hormones, 1-25-dihydroxyvitamin D3 and retinoic acid) act by triggering receptor binding in the regulatory regions of the genes. Hydrophylic hormones (peptide and glycoprotein hormones, growth factors, epinephrine) act indirectly via membrane receptors. They modify, via second messagers, the efficacy of transcription factors. Thirdly, the connection and competition between regulatory factors is studied. Interferences are known between hormones themselves or between receptors and non receptor proteins. They permit the best fit between environment and gene activity in each cell of the organism.

Cell Membrane↗
PubMed1989

Non-classical antiestrogenic actions of dexamethasone in variant MCF-7 human breast cancer cells in culture.

The aim of this work was to determine whether dexamethasone (Dex), a synthetic glucocorticoid, counteracts the stimulatory effects of estradiol (E2) on MCF-7 cells. We have shown that Dex inhibits in a dose-dependent fashion the estradiol-stimulated cell proliferation. This inhibition (ID50 congruent to 5-10 nM), which is complete at 100 nM Dex, is prevented by the antiglucocorticoid RU 486 and is clearly different from that found with trans-4-OH-tamoxifen because the inhibition due to a fixed concentration of Dex is not abolished by a high concentration of estradiol. This inhibitory effect displays some degree of specificity. Progesterone and the progestins R 5020 and ORG 2058 are without effect and Dex does not alter the triiodo-L-thyronine-stimulated cell growth. To characterize further the antiestrogenic action of Dex, the effects of this drug on specific responses to estradiol were studied. (1) Among the positive responses to estradiol two are prevented by Dex (the increase of concentration of progestin receptors and that of immunoreactive insulin-like growth factor I, IR-IGF-I, in conditioned medium) and two are insensitive to Dex (the enhancement of the secretion of 52,000 and 160,000 Mr proteins). (2) A negative response to estradiol (the down-regulation of estrogen receptor) is not prevented but rather accentuated by Dex. Thus, Dex counteracts the stimulatory effects of estradiol on the proliferation of MCF-7 cell variants characterized by progestin insensitivity. This non-classical antiestrogenic effect could be due in part to the attenuation of the E2-induced IR-IGF-I secretion and, less probably, to the accentuation of the down-regulation of E2 receptors. It could account for certain therapeutic and/or side effects of glucocorticoids on estrogen target cells.

Breast Neoplasms↗
PubMed1989

Rearrangements and point mutations of P450c21 genes are distinguished by five restriction endonuclease haplotypes identified by a new probing strategy in 57 families with congenital adrenal hyperplasia.

Congenital adrenal hyperplasia (CAH) is caused by disorders of the P450c21B gene, which, with the P450c21A pseudogene, lies in the HLA locus on chromosome 6. The near identity of nucleotide sequences and endonuclease cleavage sites in these A and B loci makes genetic analysis of this disease difficult. We used a genomic DNA probe that detects the P450c21 genes (A pseudogene, 3.2 kb; B gene, 3.7 kb in Taq I digests) and the 3' flanking DNA not detected with cDNA probes (A pseudogene, 2.4 kb; B gene, 2.5 kb) to examine Southern blots of genomic DNA from 68 patients and 165 unaffected family members in 57 families with CAH. Of 116 CAH-bearing chromosomes, 114 could be sorted into five easily distinguished haplotypes based on blots of DNA digested with Taq I and Bgl II. Haplotype I (76 of 116, 65.6%) was indistinguishable from normal and therefore bore very small lesions, presumably point mutations. Haplotype II (4 of 116, 3.4%) and haplotype III (8 of 116, 6.9%) had deletions and duplications of the P450c21A pseudogene but had structurally intact P450c21B genes presumably bearing point mutations; point mutation thus was the genetic defect in 88 of 116 chromosomes (75.9%). Haplotypes IV and V lack the 3.7-kb Taq I band normally associated with the P450c21B gene. Haplotype IV (13 of 116, 11.2%) retains all other bands, indicating that the P450c21B gene has undergone a gene conversion event, so that it is now also associated with a 3.2-kb band. Haplotype V (13 of 116, 11.2%) lacks the 2.4-kb Taq I fragment and the 12-kb Bgl II fragments normally associated with the P450c21A pseudogene, as well as lacking the 3.7-kb Taq I fragment, indicating deletion of approximately 30 kb of DNA, resulting in a single hybrid P450c21A/B gene. Most (114 of 116, 98%) CAH alleles thus can easily be classified with this new probing strategy, eliminating many ambiguities resulting from probing with cDNA.

Adrenal Hyperplasia, Congenital↗
PubMed1989

[Contribution of molecular biology to the prevention of cystic fibrosis. Experience in Lyon].

Enzymatic prenatal diagnosis of cystic fibrosis was performed in 113 amniotic fluids and DNA polymorphism was studied in 104 families, including 28 cases with prenatal material analysis. According to the results, the enzymatic diagnosis should be cautiously interpreted when the risk is less than 1/4. In these situations DNA analysis in the parents is very helpful to assess the reliability of enzymatic diagnosis.

Amniotic Fluid↗
PubMed1989

[Meleney's postoperative gangrene].

The authors report the case of a 40 years old man undergoing MOPP chemotherapy for stage III Bb type 2 Hodgkin's disease with immune depression. Six years later he developed two episodes of unilateral transient loss of vision and severe stenosis of the left common carotid artery was found leading to surgical reimplantation of the left subclavian artery. Quickly spreading cutaneous necrosis was observed 5 days after surgery on the scar and the irradiated area: Meleney's postoperative gangrene, an unusual and frequently fatal complication of unknown cause. The patient recovered in two months after wide excision of the necrosed tissues and a skin autograft.

Adult↗
PubMed1988

Aging and diabetes increase the aggregating potency of rat skin collagen towards normal platelets.

Acid-soluble collagen samples were prepared from individual skins of 24 month old rats (n = 8), 2 month old young controls (n = 8) and from 6 month old streptozotocin-diabetic rats (n = 5) and their age-matched controls (n = 10). Less collagen was obtained by acid extraction and salt precipitations from skins of diabetic and aged rats than from those of their respective controls. The collagen preparations from diabetic and aged rats showed an increased ratio of beta/alpha components. The rate of "in vitro" fibrillogenesis was less for collagen from diabetic rats than from controls. It was not modified for collagens from aged rats. The aggregating potency towards normal human platelets was markedly increased for collagens from aged and diabetic rats: reduced latency time (p less than 0.01) and increased velocity (p less than 0.01) were observed for collagens from aged rats when compared with young rats (16.5 micrograms/ml). Increased velocity (p less than 0.01) was also observed for collagens from diabetic rats (8.25, 11 and 16.5 micrograms/ml), without modification of latency time.

Aging↗
PubMed1988

[Radiotherapy before amputation of the rectum for cancer. 100 cases].

Between 1977 and 1982, 100 patients were treated with pelvic irradiation of 3000 rads given over a 3-week period for a carcinoma located in the lower third (51 cases) or the middle third (49 cases) of the rectum. The irradiation was well tolerated by all patients. The tumour disappeared in 4 patients who were not operated upon and survived for more than 5 years. Among the remaining 96 patients, 18 of whom had fixed lesions, rectal excision was performed in 87 (90.6 per cent) and was considered curative in 75 (78 per cent). Pathological examination of the surgical specimens revealed the absence of tumour in 4 cases. There were 2 post-operative deaths. After curative excision, the 5-year survival rate was 70 per cent and the locoregional recurrence rate was 8 per cent, with perineal recurrence in only one case. Patients treated with pre-operative irradiation have been compared with a historical series of patients who had abdominoperineal excision without irradiation. In the present series of irradiated patients, thromboembolic complications were more severe, and the problems encountered with healing of the perineum were solved by changing the surgical technique in order to close the perineal wound. The rectal tumours were smaller, with a smaller proportion of tumours of more than 5 cm in diameter (P less than 0.001), but there was no significant change in Duke's stage distribution. The 5-year survival rate was higher (70 per cent versus 55.3 per cent; P less than 0.05), and the 5-year locoregional recurrence rate was lower (8 per cent versus 18.4 per cent; P less than 0.05).

Adenocarcinoma↗
PubMed1988

Larva migrans of the oral mucosa.

A case of buccal larva migrans is presented. This rare peculiar localization is discussed. The different treatments are mentioned with special regard to the topical and systemic use of the thiabendazole.

Administration, Oral↗
PubMed1988

Nail changes in alopecia areata: light and electron microscopy.

Fragments of nail keratin removed with tweezers from patients suffering from alopecia areata were examined using light microscopy and electron microscopy. The results obtained from these two techniques show nail changes which are slits, cupuliform dips of the upper edge and parakeratosis, under light microscopy; vacuoles, depletion of keratin fibers, and electron-dense fibrillary deposits, under electron microscopy. These changes predominate in the nail plate with a maximum in the upper part while the subungual keratin is preserved. A serious disorder of the matrix keratinization is probably the source of this preferential localization. To determine whether it is a disorder of the keratin fibers themselves or rather of the interfilamentary matrix and especially of the filaggrin system will require further biochemical and immunological studies.

Alopecia Areata↗
PubMed1988

[Meningovascular syphilis. Apropos of 4 cases].

In four cases of stroke, it is only the systematic practice of serologic tests for syphilis that has permitted the true diagnosis and the true treatment. We observed cerebral, brain-stem and medullar infarction and one case of cerebellar haemorrhage. Meningo vascular syphilis is now the most frequent of the central nervous system lesion. Cerebrospinal fluid is always abnormal in active disease. The decrease of cell count is the best control of the treatment that needs high doses of Penicillin G.

Aged↗