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Biomedical subjects

A Lefebvre

Publications and source records attributed to A Lefebvre.

At least 37 records · Page 2Linked to original sources
PubMed1996

[Spontaneous Listeria monocytogenes peritoneal infection complicating hepatic transplantation].

The incidence of listeriosis is increased in immunosuppressed patients. We report a case of spontaneous bacterial peritonitis with bacteraemia caused by Listeria monocytogenes in a 47-year old woman with liver transplantation. Complete recovery was achieved after amoxicillin and amikacin therapy. High doses of corticosteroids and OKT3 monoclonal therapy may have favoured the occurrence of infection. In liver transplant recipients, regular stool screening could be proposed, and trimethoprim-sulfamethoxazole antibioprophylaxy could be used when Listeria monocytogenes is isolated in stool culture or immunosuppressive therapy is increased.

Female↗
PubMed1995

Structural behavior of the CpG step in two related oligonucleotides reflects its malleability in solution.

We report on the determination of the solution structure of two sequence-related oligonucleotides, d(GTACGTAC)2 and d(CATCGATG)2. Results have been obtained by using a combined approach of (a) two-dimensional NMR, including proton and phosphorus experiments, (b) restrained molecular mechanics performed with sugar phase angle, backbone epsilon angle, and NOE distances as input, and (c) back-calculation refinements against the NOE spectra at various mixing times. The two oligonucleotides adopt the B-DNA structure with, however, noticeable differences centered on their core sequence and especially the CpG step. Due to the permutation of its flanking residues, the CpG step modifies its twist values and backbone epsilon value; globally, the CpG step appears more flexible within the tetranucleotide TCGA than ACGT. The solution structure of d(GTACGTAC)2 differs from the previously reported X-ray structure, which was found to be A-form throughout [Takusagawa, F. (1990) J. Biomol. NMR 3, 547-568]. On the other hand, in the X-ray structure of d(CCAACGTTGG)2 [Privé et al. (1991) J. Mol. Biol. 217, 177-199] the structure of the ACGT sequence is similar to that found in solution d(GTACGTAC)2. Similarly, the central TCGA tetranucleotide of d(CATCGATG)2 presents a solution structure analogous to that observed on the X-ray structures of both d(CGATCGATCG)2 [Grzeskowiak, et al. (1991) J. Biol. Chem. 266, 8861-8883] and d(CGATCGmeATCG)2 [Baïkalov, et al. (1993) J. Mol. Biol. 231, 768-784]. At the end we discuss the possible biological significance of the particular structures exhibited by the ACGT and TCGA tetranucleotides.

Base Sequence↗
PubMed1995

Sequence dependent effects of CpG cytosine methylation. A joint 1H-NMR and 31P-NMR study.

The impact of cytosine methylation in the central CpG step of two closely related octanucleotide duplexes d(CATCGATG)2 and d(CTTCGAAG)2 was examined by 1H-NMR and 31P-NMR experiments, and a quantitative structural analysis was performed using the NOE-derived distances, the sugar puckers and the epsilon torsion angles. The two starting oligonucleotides displayed a B-DNA conformation with, however, significant local structure differences. Although the methylated oligonucleotides retained their B-DNA conformation, different structural and thermal stability effects were observed. The magnitude of the methylation effects was to depend on the initial conformation of the CpG site, which is governed by the nature of the dinucleotide AT or TT located on the CpG flanks. As an example of sequence dependence, the methylation of CpG entailed larger conformational variation in d(CATCGATG)2 than in d(CTTCGAAG)2. In this study, the 1H and 31P chemical-shift parameters averred as extremely sensitive probes for detecting subtle conformational changes. Finally, our comparative results may aid our understanding of the structural and related biological effects produced by cytosine methylation in DNA.

5-Methylcytosine↗
PubMed1995

Choroidal biopsy in the diagnosis of a suspect intraocular lesions.

A thirty-eight year-old man, treated medically since 1985 for a chronic pancreatitis, showed a choroidal infiltrate in the superior mid periphery of the left fundus. A thorough systemic examination could not reveal an underlying cause. The differential diagnosis of the lesion included metastasis, intraocular lymphoma and sarcoidosis. Two months later the lesion had increased both on fundoscopy and echography and was accompanied by a serous macular detachment. A choroidal biopsy showed a moderately well differentiated mucinous adenocarcinoma. The primary site could not be determined. The mucinous character is rather suggestive for a gastrointestinal origin. Gastro intestinal choroidal metastases, and more specifically the pancreatic ones, are however rare.

Adenocarcinoma↗
PubMed1994

The presence of two cytochrome P450 aldosterone synthase mRNAs in the hamster adrenal.

We isolated a cDNA from a hamster adrenal cDNA library which was similar in sequence to those of the mouse and rat P450c18 cDNAs. The hamster P450c18 cDNA, however, was shorter than the rat and mouse P450c18 cDNAs at its 5'-end and the peptide leader sequence was absent. From a hamster genomic library we isolated and sequenced the first seven exons and a 5'-flanking region of the first P450c18 gene exon. With this information we were able to generate a P450c18 cDNA containing the peptide leader sequence using the polymerase chain reaction. Northern analyses were performed on adrenals from hamsters maintained on a low sodium diet for 0, 4, 7 and 10 days using a 32P-labeled sequence specific to P450c18; two mRNA bands were found at 2 and 3.4 kb. The intensity of both bands was increased about 3- to 5-fold under sodium restriction compared to controls. A distinct mRNA band of 2.3 kb hybridized with an oligonucleotide specific to P450(11) beta and its intensity did not change following low sodium intake. Immunoblotting analyses were performed using an antibovine adrenal P450(11) beta antibody that does not discriminate between P450(11) beta and P450c18 proteins. Three bands were detected at 52, 48 and 45 kDa in homogenate preparations of entire glands. Furthermore, the 45 kDa protein band was present in homogenates of the zona glomerulosa and absent in homogenates of the zone fasciculata-reticularis. In conclusion, these results show that the hamster adrenals express P450c18 as do mouse, rat and human adrenal glands. Furthermore, two P450c18 mRNAs, which are inducible by a low sodium intake, are present in the hamster adrenal vs one for the rat. The physiological role of these two hamster adrenal mRNA species remains to be elucidated.

Adrenal Glands↗
PubMed1993

Congenital ectropion uveae with glaucoma.

Congenital ectropion uveae (CEU) is a rare, non progressive anomaly characterised by the presence of iris pigment epithelium on the anterior surface, an anterior iris insertion, dysgenesis of the drainage angle and glaucoma. The condition is characteristically unilateral and rarely hereditary. The current theory of development arrest is discussed. We report three cases with CEU of which two already developed glaucoma. All patients with CEU should be carefully examined periodically to detect glaucoma.

Child↗
PubMed1991

Short-term effects of ACTH on the low-density lipoprotein receptor mRNA level in rat and hamster adrenals.

Low-density lipoprotein (LDL) receptor mRNA was found in both rat and hamster adrenals. Within 30 min after ACTH administration a significant increase in the levels of both LDL receptor and 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) mRNAs was observed in rat adrenals; these levels remained increased for up to 240 min. The increase in the levels of LDL receptor and HMG-CoA reductase mRNAs produced by ACTH was reduced by co-administration of aminoglutethimide while, at the same time, the adrenal cholesterol content of rats treated with both aminoglutethimide and ACTH was significantly increased compared with that in groups treated with ACTH alone. Cycloheximide also induced increased levels of rat adrenal mRNAs for LDL receptor and HMG-CoA reductase, but this effect was not additive with that of ACTH. These results suggest that, in the rat, the short-term effect of ACTH on the levels of mRNAs for the LDL receptor and HMG-CoA reductase is similarly controlled and might be mediated through changes in the adrenal cholesterol content. In the hamster adrenal, however, no significant fluctuations were found in the level of LDL receptor mRNA, although a marked increase was found in the level of HMG-CoA reductase mRNA, 2 h after ACTH administration. This indicates that an important effect of ACTH on cholesterol metabolism in the hamster adrenal is at the level of HMG-CoA reductase. In the hamster, therefore, where the main source of cholesterol for the adrenal gland is de-novo synthesis, it seems that a complex mechanism is involved in the control of LDL receptor gene expression.

Adrenal Glands↗
PubMed1990

Effect of ACTH suppression on adrenal 3-hydroxy-3-methylglutaryl coenzyme A reductase mRNA in 4-aminopyrazolopyrimidine-treated rats.

4-Aminopyrazolopyrimidine (4-APP) treatments to rats for 3 days induced 2-fold increase of circulating ACTH and 11-fold increase of adrenal 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase mRNA compared to NaCl-treated controls. This in vivo model was used to study the effect of the suppression of ACTH secretion on the adrenal HMG-CoA reductase mRNA level. Dexamethasone (Dex) administration to 4-APP-treated rats caused a rapid and parallel decline of the levels of plasma ACTH and adrenal HMG-CoA reductase mRNA to 50% within 2.5 h, whereas the free and esterified cholesterol content was increased 5 and 9.4 times respectively. These changes could be counteracted by the co-administration of ACTH with Dex. Aminoglutethimide (AG) administration to 4-APP-treated rats, which increased the adrenal esterified cholesterol content (7.5 times), decreased the HMG-CoA reductase mRNA level (44%), despite plasma ACTH level remaining elevated. Moreover, the participation of newly synthesized protein(s) in the lowering of adrenal HMG-CoA reductase mRNA level induced by ACTH suppression is suggested by the fact that cycloheximide (Cyclo), when co-administered with AG, completely blocked the decrease of HMG-CoA reductase mRNA level, despite the plasma ACTH level decreasing by 68% and the free and esterified cholesterol content increasing 3.9 and 12.3 times, compared to 4-APP-treated rats. Furthermore, the specificity of these effects was established by the fact that the beta-actin mRNA level was not affected by the administration of either Dex, AG, Cyclo, or AG + Cyclo to 4-APP-treated rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenine↗
PubMed1990

The double-stranded RNA associated with the '447' cytoplasmic male sterility in Vicia faba is packaged together with its replicase in cytoplasmic membranous vesicles.

The 447 male sterility trait in Vicia faba is strictly correlated with the presence of well-defined membranous vesicles or 'cytoplasmic spherical bodies' not found in fertile isogenic maintainer plants, and by the occurrence of a discrete high molecular weight double-stranded RNA. We have purified these cytoplasmic membranous vesicles and find that they contain the dsRNA together with an RNA-dependent RNA polymerase whose activity depends upon the presence of Mg2+, requires the four-nucleoside triphosphates and is unaffected by inhibitors of cellular transcriptases, e.g. alpha-amanitin and Actinomycin D. The dsRNA can be labelled in vitro by incubating the cytoplasmic vesicles with radioactive NTPs, and the RNA synthesized in vitro is also in a double-stranded form as judged by its resistance to RNase digestion at high salt and its behaviour upon CF-11 chromatography. Treatment of the vesicles with a non-ionic detergent releases the dsRNA in the form of a complex with the RNA-dependent RNA polymerase. The enzyme can still carry out the specific synthesis of dsRNA in these solubilized complexes. The cytoplasmic vesicles therefore isolate this vertically transmitted, self-replicating dsRNA from the cellular milieu: the possible mode of action and relevance of this novel genetic element to the 447 cytoplasmic male sterility trait are discussed.

Cytoplasm↗
PubMed1990

International labour migration from two Pakistani villages with different forms of agriculture.

"This paper is an analysis of the socio-economic situation of two Punjabi villages [in Pakistan]. It makes an attempt to explain why the villagers of these rural places have to seek work abroad. The first part of the paper deals with the agricultural conditions, the non-agricultural activities available to the villagers, and the budgets of different social categories found in the villages. The second part examines the effects of the process of migration on the young people. It particularly discusses the profile of the migrant, the problems faced by him before his departure, the remittances and their utilization, and the impact of emigration upon women's economic role in the villages and upon the traditional social conflicts. The important conclusion of the paper is that these villagers cannot ensure their social, economic, and cultural reproduction."

Agriculture↗
PubMed1990

[Treatment of anemia in chronic hemodialysis patients with recombinant human erythropoietin: long-term results in 15 patients].

Recombinant human erythropoietin (rHu-EPO) was given during 12 to 20 months in 15 long term haemodialysis anaemic (mean Hb: 6.6 +/- 1 g/dl) patients who required no blood transfusion. Patients over 65, or with severe arterial disease or with uncontrolled hypertension were not included in this trial. Correction of anaemia (mean Hb 12.1 +/- 0.6 g/dl) was achieved in all patients and maintained all along the study. An improved sense of wellbeing and increased exercise tolerance were reported by all patients. Appropriate maintenance dosage of rHu-EPO was 74 +/- 6 U/kg i.v. twice weekly. High dose oral and/or intravenous iron therapy was necessary in the absence of previous marked iron overload. One retinal venous thrombosis was the sole severe side-effect encountered. A slight but significant increase of blood pressure was observed with the need of intensifying previous anti-hypertensive therapy in one patient and of starting one in one another. Fine adjustment of the dry weight was necessary to maintain blood pressure in the normal range. Heparin requirements increased in the majority of patients because of hollow fibre clotting but there was no evidence of decreased efficacy of dialysis. In two patients clotting of arteriovenous fistula was not obviously related to the rHu-EPO treatment.

Adult↗
PubMed1989

Hormonal regulation of 3-hydroxy-3-methylglutaryl coenzyme A reductase mRNA in the rat adrenal gland.

We studied the effect of ACTH on 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase enzyme. Reductase activity and reductase mass were enhanced by 22- and 6.2-fold respectively in one series of experiments, whereas in another the levels of reductase activity, reductase mass, and reductase mRNA were increased 6.6-, 3.6- and 2.2-fold respectively, following daily administration of exogenous ACTH for 3 days. Daily injection of 4-aminopyrazolopyrimidine (4-APP) to rats for 3 days increased circulating ACTH level 5.4-fold, whereas adrenal HMG-CoA reductase activity, reductase mass and reductase mRNA levels were greatly increased 36-, 10- and 16-fold, respectively. To counteract the effect of elevated plasma ACTH, dexamethasone acetate (Dex) was administered to 4-APP treated rats. At 3 h post Dex administration, plasma ACTH and corticosteroids levels were effectively decreased by 58 and 59%, respectively. The levels of adrenal HMG-CoA reductase mRNA, reductase activity and reductase mass were also diminished by 38, 31 and 40%, respectively. Our results show that rat adrenal HMG-CoA reductase can respond rapidly to hormonal changes, presumably through variations in circulating ACTH levels.

Adenine↗