Biomedical subjects
N Petit
Publications and source records attributed to N Petit.
Mutation analysis in 16 patients with mtDNA depletion.
Sixteen unrelated Southern European patients with the mitochondrial depletion syndrome (MDS) were analyzed for mutations in the TK2 and DGUOK genes. Three novel mutations were identified in TK2 (R183G, R254X, and 142insG). When we analyzed additional genes involved in the dNTPs pool, such as SLC25A19 (DNC) and NT5M (d-NT2), we did not detect mutations. The current study suggest that scanning the TK2, DGUOK, SLC25A19, and NT5M genes is likely to help about 10% of MDS families in terms of genetic counseling. Also, our findings indicate that genotype-phenotype correlations are not straightforward in MDS.
Experience of a combination including indinavir 400 mg plus ritonavir 200 mg twice daily in HIV-infected patients: pharmacokinetic data.
Low doses of ritonavir, a strong inhibitor of cytochrome P450 3A4, enhances the pharmacokinetic profile of indinavir with increased serum levels. We assessed the indinavir-ritonavir 400/200 twice daily combination in 17 HIV-infected patients focusing on the pharmacokinetic data and the tolerance of this regimen. IDV trough and peak concentrations were measured by high-performance liquid chromatography. Median indinavir trough and peak concentrations were 553 ng/ml and 3626 ng/ml, respectively. A good tolerance was observed except for three patients who experienced a major toxicity. Only one dose adjustment was related to indinavir toxicity. Considering the fact that Cmax is mainly responsible of the adverse effects, particularly renal stones, the indinavir-ritonavir 400/200 mg twice daily regimen offers a well-tolerated combination with an increased Cmin but a lower Cmax compared with both the standard tid regimen and higher dose of IDV-RTV regimens.
Germ cell tumors in patients infected by the human immunodeficiency virus.
BACKGROUND: The objective of this study was to assess the natural history of the two disease courses, patient immune system tolerance, and results of therapy in human immunodeficiency virus (HIV)-infected patients with germ cell tumors (GCT). METHODS: From 1985 to 1996, 34 HIV-infected men received a diagnosis of GCT. Their charts were analyzed retrospectively. RESULTS: Sixteen patients had seminomas, and 18 had nonseminomatous GCTs (NSGCT); 71% had International Union Against Cancer (UICC), 1997 Stage I-II GCTs. At the time of chemotherapy, 69%, 6%, and 25% of patients with advanced NSGCT were in the International Germ Cell Consensus Classification (IGCCC) good, intermediate, and poor prognostic group, respectively. All except 1 of the 10 patients with advanced seminomas were in the IGCCC good prognostic group. At diagnosis of GCT, 85% of patients were classified as having asymptomatic HIV infection or only persistent generalized lymphadenectomy. The median CD4 cell count was 325/microL (range, 6-1125). Overall, 26 patients were given chemotherapy, but the planned dose intensity was respected in only 15 (57%) patients. Severe toxic effects included febrile neutropenia in 35% of patients. During chemotherapy, zidovudine, prophylactic granulocyte colony-stimulating factor (G-CSF), and a Pneumocystis carinii prophylaxis were given in 19%, 23%, and 35% of cases, respectively. CD4 cell count decreased in 7 (64%) of 11 patients during chemotherapy. Infradiaphragmatic radiotherapy was given in 10 cases and was clinically well tolerated. At a median follow-up of 27 months (range, 3-150), 50% of patients were alive, and only 18% of patients died of GCT. Two patients developed a non-GCT malignancy while in complete remission, namely, Hodgkin disease and an acute leukemia. CONCLUSIONS: The prognosis of GCT in HIV-infected patients is mostly dictated by the HIV infection. Patients should be treated according to stage and histologic subtype, although dose reduction of chemotherapy might be necessary in approximately half of the patients. Close surveillance of neutrophil and CD4 cells counts, as well as the use of G-CSF and systematic anti-Pneumocystis carinii prophylaxis are recommended during chemotherapy. The use of highly active antiretroviral therapy during chemotherapy for GCT requires a prospective assessment.
Mutations in SEPN1 cause congenital muscular dystrophy with spinal rigidity and restrictive respiratory syndrome.
One form of congenital muscular dystrophy, rigid spine syndrome (MIM 602771), is a rare neuromuscular disorder characterized by early rigidity of the spine and respiratory insufficiency. A locus on 1p35-36 (RSMD1) was recently found to segregate with rigid spine muscular dystrophy 1 (ref. 1). Here we refine the locus and find evidence of linkage disequilibrium associated with SEPN1, which encodes the recently described selenoprotein N (ref. 2). Our identification and analysis of mutations in SEPN1 is the first description of a selenoprotein implicated in a human disease.
Technical knockout, a Drosophila model of mitochondrial deafness.
Mutations in mtDNA-encoded components of the mitochondrial translational apparatus are associated with diverse pathological states in humans, notably sensorineural deafness. To develop animal models of such disorders, we have manipulated the nuclear gene for mitochondrial ribosomal protein S12 in Drosophila (technical knockout, tko). The prototypic mutant tko(25t) exhibits developmental delay, bang sensitivity, impaired male courtship, and defective response to sound. On the basis of a transgenic reversion test, these phenotypes are attributable to a single substitution (L85H) at a conserved residue of the tko protein. The mutant is hypersensitive to doxycyclin, an antibiotic that selectively inhibits mitochondrial protein synthesis, and mutant larvae have greatly diminished activities of mitochondrial redox enzymes and decreased levels of mitochondrial small-subunit rRNA. A second mutation in the tko gene, Q116K, which is predicted to impair the accuracy of mitochondrial translation, results in the completely different phenotype of recessive female sterility, based on three independent transgenic insertions. We infer that the tko(25t) mutant provides a model of mitochondrial hearing impairment resulting from a quantitative deficiency of mitochondrial translational capacity.
Simultaneous occurrence of kaposi's sarcoma and chronic myelogenous leukemia.
We report here a 75-year-old man from South France who developed Kaposi's Sarcoma (KS) 5 months after diagnosis of Philadelphia-chromosome positive chronic myelogenous leukemia (CML). He was found positive for HHV-8 by PCR, negative for both HIV 1 and HIV 2 by serology, and had a normal CD4/CD8 ratio. Favourable evolution of both CML and KS has been obtained with vinblastine and interferon alpha treatment. The patient is currently alive in complete remission of SK and major cytogenetic remission of CML with a 48 month follow-up. Since no immune deficiency could be documented in the patient, this rare observation suggests that CML may have triggered the onset of SK through cytokine release.
The pathophysiology of mitochondrial biogenesis: towards four decades of mitochondrial DNA research.
Mitochondria are with very few exceptions ubiquitous organelles in eukaryotic cells where they are essential for cell life and death. Mitochondria play a central role not only in a variety of metabolic pathways including the supply of the bulk of cellular ATP through oxidative phosphorylation (OXPHOS), but also in complex processes such as development, apoptosis, and aging. Mitochondria contain their own genome that is replicated and expressed within the organelle. It encodes 13 polypeptides all of them components of the OXPHOS system, and thus, the integrity of the mitochondrial DNA (mtDNA) is critical for cellular energy supply. In the past 12 years more than 50 point mutations and around 100 rearrangements in the mtDNA have been associated with human diseases. Also in recent years, several mutations in nuclear genes that encode structural or regulatory factors of the OXPHOS system or the mtDNA metabolism have been described. The development of increasingly powerful techniques and the use of cellular and animal models are opening new avenues in the study of mitochondrial medicine. The detailed molecular characterization of the effects produced by different mutations that cause mitochondrial cytopathies will be critical for designing rational therapeutic strategies for this group of devastating diseases.
Quantitative analysis, by ultrastructural in situ hybridization, of mitochondrial genomes and their expression in mid-gut and ovarian cells of a mutant strain of Drosophila subobscura.
In the mitochondrial deletion mutant strain studied here, two types of DNA coexist (heteroplasmy): intact mtDNA (15.9 kb) and mutant mtDNA (10.9 kb), which represents about 80% of the mitochondrial genomes in somatic tissues. The heteroplasmy level is lower in ovary (63%). Mutation is transmitted unchanged through generations. Quantitative analysis of in situ DNA hybridization demonstrated that for the 12SrDNA probe, of a gene outside the deletion, the mitochondrial DNA cellular content in the studied cells of the mutant strain is 1.5 times higher than in the wild-type strain. For the probe encoding Cyto b, a mitochondrial gene affected by the mutation, the ratios (mutant versus wild-type content) differ according to cell type: close to 0.4 in MGE cells and 0.7 in ovary cells. These values indicate heteroplasmic levels of about 72% in MGE cells and 50% in stage 10 oocytes, which is lower than that previously reported for stage 14 oocytes (60%) and embryos (69%). Analysis of in situ RNA hybridization showed that for the 12SrDNA probe, the transcript concentrations do not differ significantly between MGE cells and cells of germinal origin from the two strains. For the Cyto b probe, the mutant RNA/wild-type RNA ratios are lower in somatic cells than in stage 10 nurse cells and oocytes, but in each case less than expected. These studies indicate that the progressive heteroplasmy increase may be related to intense phases of mitochondria biogenesis and that different compensatory phenomena may exist.
Investigation of stretching behaviour induced by the selective 5-HT6 receptor antagonist, Ro 04-6790, in rats.
1. The present study examined the effects of the selective 5-HT6 receptor antagonist 4-amino-N-(2, 6 bis-methylamino-pyrimidin-4-yl)-benzene sulphonamide (Ro 04-6790) on locomotor activity and unconditioned behaviour in male Sprague Dawley rats (230-300 g). 2. In non-quantified behavioural observations, animals treated with Ro 04-6790 (3, 10 or 30 mg kg(-1), i.p) showed no overt behavioural signs except a dose-dependent reduction in locomotor activity and a behavioural syndrome of stretching, yawning and chewing. The latter behaviour was most pronounced between 30 and 90 min following the administration of Ro 04-6790. 3. Detailed analysis of the stretching and yawning behaviour showed that Ro 04-6790 (3, 10 or 30 mg kg(-1), i.p.) dose-dependently induced stretching. The number of stretches observed following treatment with either Ro 04-6790 (10 mg kg(-1) i.p.) or Ro-04-6790 (30 mg kg(-1), i.p.) was significantly greater than that observed in saline-treated rats. The yawning behaviour, however, was not dose-dependent nor was the number of yawns in any of the drug treated groups significantly greater than in those treated with saline. 4. Pretreatment (30 min) with the non-selective muscarinic antagonists scopolamine (0.1, 0.3 or 1 mg kg(-1), i.p.) and atropine (0.3, 1 or 3 mg kg(-1), s.c.) but not methylatropine (1, 3 or 10 mg kg(-1), s.c) significantly inhibited stretching induced by Ro 04-6790 (30 mg kg(-1), i.p.). 5. The dopamine D2-like receptor antagonist, haloperidol (0.03, 0.1 or 0.3 mg kg(-1), s.c.) given at the same time as Ro 04-6790 (30 mg kg(-1), i.p.) had no effect on the stretching induced by the 5-HT6 antagonist. 6. These data suggest that systemic injection of the 5-HT6 antagonist, Ro 04-6790, produces a stretching behaviour that appears to be mediated by an increase in cholinergic neurotransmission in the CNS and which could be a useful functional correlate for 5-HT6 receptor blockade. There is no evidence for dopamine D2-like receptor involvement in this behaviour.
Developmental changes in heteroplasmy level and mitochondrial gene expression in a Drosophila subobscura mitochondrial deletion mutant.
Eighty percent of DNA molecules are deleted in the mitochondrial population of an adult mutant strain of D. subobscura. Both intact and deleted genomes are autonomous monomers. The heteroplasmy level, which is lower in germ tissue, increases from the oocytes (60%) to the third larval instar (83%), and is then maintained throughout the life of the fly. The mtDNA/nuclear DNA ratio is on average two-times greater in the heteroplasmic strain than in the wild-type strain, irrespective of the stage, but the cellular content of mitochondria is elevated only in the embryos and pupae of the mutant strain. The steady state concentrations (SSCs) of the transcripts affected by the deletion are greatly reduced at the larval and adult stages, and less so at the pupal stage of the mutant strain compared with the wild-type. The SSCs of these transcripts are identical in the two strains at the embryonic stage. The fusion transcript, indicating that the deleted genome is expressed, was detected at all stages. The mechanisms involved in the changes in the heteroplasmy level during the course of development and in its maintenance from the third larval instar onwards are discussed.
The effects of tamoxifen on endometrial insulin-like growth factor-1 expression.
OBJECTIVE: To determine whether modulation of insulin-like growth factor-1 and insulin-like growth factor-binding protein-1 expression underlies the uterotropic effects associated with tamoxifen therapy in postmenopausal breast cancer patients. METHODS: Using immunohistochemical techniques, we analyzed 37 endometrial specimens from biopsies (n = 18) or hysterectomies (n = 19) for Ki-67, insulin-like growth factor-1, and insulin-like growth factor-binding protein-1 expression. Specifically, five secretory- and three proliferative-phase endometrial specimens were used as controls; 20 specimens (including two endometrial adenocarcinomas) were analyzed from postmenopausal breast cancer patients treated with tamoxifen (20 mg/day) for at least 6 months; and nine endometrial adenocarcinoma specimens from patients not treated with tamoxifen were studied. Intensity of immunostaining was quantified using digitized imaging techniques. RESULTS: Insulin-like growth factor-1 and insulin-like growth factor-1-binding protein-1 were found to be expressed in normal and neoplastic endometrium of all patients, regardless of tamoxifen treatment. However, insulin-like growth factor-1 expression varied cyclically in histologically normal endometrium, was reduced in undifferentiated endometrial tumors, and was upregulated in tamoxifen-treated specimens. Insulin-like growth factor-binding protein-1 immunostaining did not vary during the menstrual cycle, but it was reduced significantly in benign tamoxifen-exposed tissue and endometrial adenocarcinomas, regardless of degree of differentiation or tamoxifen exposure. No correlation was found between the expression of insulin-like growth factor-1 and insulin-like growth factor-binding protein-1 and the proliferative indices of the tissues examined. CONCLUSION: The expression of insulin-like growth factor-1 and insulin-like growth factor-binding protein-1 in the uterus supports an autocrine and/or paracrine role for these proteins in endometrial physiology. Although further studies are needed, our investigation suggests that altered expression of insulin-like growth factor-1 and insulin-like growth factor-binding protein-1 may contribute to the uterotropic effects of tamoxifen.
[Hodgkin's disease in patients infected with the human immunodeficiency virus].
INTRODUCTION: Hodgkin's disease in patients infected by the human immunodeficiency virus (HIV) is still not part of the definition of acquired immune deficiency syndrome. Nonetheless, this entity has a particular presentation when compared to the disease occurring in immune-competent patients. CURRENT KNOWLEDGE AND KEY POINTS: Increased frequency (> 75%) of advanced anatomical stages and extranodular localizations (Ann Arbor system stages III and IV) has been outlined in HIV-infected patients. Mediastinal involvement is more unusual in immunocompromised than in immune-competent patients. The presence of B symptoms (fever, weight loss, nocturnal sweats) is very frequent. Finally, the predominance of mixed cellularity (type 3) characterizes Hodgkin's disease in immunocompromised patients. Due to either the immunodeficiency, antiretroviral treatments, poor hematological tolerance in response to chemotherapy, or to advanced anatomical stages, disease management may be hampered. Current therapeutical approaches often obtain complete remission; however, some deaths are still related to the disease progression to acquired immune deficiency syndrome. FUTURE PROSPECTS AND PROJECTS: From these observations, Hodgkin's disease management in HIV-infected patients relies on therapeutical approaches similar to those used for non infected patients, with some specific recommendations. Chemotherapy should be conducted in the shortest time in order to minimize chemotherapy-induced immunosuppression. Simultaneous use of antiretroviral treatment and reinforced opportunistic infection prophylaxis are of pivotal importance. Finally, the use of hematopoietic growth factors appears to be safe regarding viral replication, but still requires further evaluation.
First case of plasma-cell leukaemia co-existing with human immunodeficiency virus infection.
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Relapse of CMV retinitis in an AIDS patient with high CD4 counts.
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Biochemical and molecular consequences of massive mitochondrial gene loss in different tissues of a mutant strain of Drosophila subobscura.
In the studied mutant strain of Drosophila subobscura, 78% of the mitochondrial genomes lost >30% of the coding region by deletion. The mutations was genetically stable. Despite this massive loss of mitochondrial genes, the mutant did not seem to be affected. Distribution of the two genome types, cell levels of mitochondrial DNA, steady-state concentrations of the mitochondrial gene transcripts, mitochondrial enzymatic activities, and ATP synthesis capacities were measured in the head, thorax, and abdomen fractions of the mutant strain in comparison with a wild type strain. Results indicate that the deleted genomes are detected in all fractions but to a lesser extent in the male and female abdomen. In all fractions, there is a 50% increase in cellular mitochondrial DNA content. Although there is a decrease in steady-state concentrations of mitochondrial transcripts of genes affected by deletion, this is smaller than expected. The variations in mitochondrial biochemical activities in the different fractions of the wild strain are upheld in the mutant strain. Activity of complex I (involved in mutation) nevertheless shows a decrease in all fractions; activity of complex III (likewise involved) shows little or no change; finally, mitochondrial ATP synthesis capacity is identical to that observed in the wild strain. This latter finding possibly accounts for the lack of phenotype. This mutant is a good model for studying mitochondrial genome alterations and the role of the nuclear genome in these phenomena.
Pancreatic ductal changes in HIV-infected patients.
BACKGROUND: AIDS-related sclerosing cholangitis occurs in patients with advanced immunodeficiency, but ductal pancreatic alterations have not been evaluated in large series. METHODS: Twenty-nine consecutive patients with a mean age of 33 years underwent ERCP for biliary work-up. Complete pancreatography was obtained in 28 patients. Serum levels of amylase were increased in 17 patients prior to ERCP. The mean duration of HIV infection was 6.1 years (range 3 to 10 years). RESULTS: Fifteen patients (53.6%) had pancreatographic changes classified according to the Cambridge classification (stage 1, 4 cases; stage 2, 7 cases; stage 3, 4 cases). Dilatations, irregularities, short stenoses of the main pancreatic duct, and irregularities of side branches were the most frequent abnormalities. Fourteen of these 15 patients (93.3%) had cholangitis and a CD4 cell count of less than 60 per cubic millimeter. Risk factors for pancreatic damage were similar in patients with and without pancreatographic changes. Opportunistic infection occurred in 14 of 15 patients with pancreatographic changes (candida, cytomegalovirus, cryptosporidia, microsporidia, and mycobacteria). CONCLUSION: Abnormal pancreatographies were found in about half of the HIV-infected patients who underwent ERCP. The pancreatographic features were suggestive of chronic pancreatitis and were closely related to the presence of AIDS-related sclerosing cholangitis.
Pharmacologic evaluation of the discriminative stimulus of metachlorophenylpiperazine.
A pharmacologic analysis of the discriminative stimulus of metachlorophenylpiperazine (mCPP) is reported. mCPP and m-trifluoromethylphenylpiperazine generalised, whereas 5-methoxy-3-(1,2,3,6-tetrahydro-4-pyridinyl)-1H-indole, 6-chloro-2-(1-piperazinyl)-pyrazine, and mesulergine partially generalised to the mCPP discriminative cue. However, although mianserin, methiothepin, ritanserin, mesulergine and N-(1-methyl-5'-indolyl)-N'-(3-pyridyl)urea hydrochloride (SB 200646) all antagonised the effect of 5-hydroxytryptamine (5-HT) on IP3 formation in the rat choroid plexus, they failed to antagonise the mCPP response in the drug discrimination studies. The 5-HT3 receptor antagonist MDL 72222 neither generalised nor antagonised the mCPP cue. These data suggest that neither the 5-HT1A, 5-HT1B, 5-HT1D, 5-HT2A, 5-HT2B, 5-HT2C, 5-HT3, 5-HT5, 5-HT6, nor 5-HT7 receptors are involved. The response does appear to be mediated by a postsynaptic 5-HT receptor, however, because fenfluramine generalised to the cue. Haloperidol generalises, and amphetamine partially antagonises the mCPP discriminative cue and low doses of apomorphine partially generalises to the mCPP cue, which suggests that a decrease in dopamine neurotransmission may also be involved.