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Biomedical subjects

G Breton

Publications and source records attributed to G Breton.

At least 19 recordsLinked to original sources
PubMed2006

Monitoring the effects of mobile phone use on the brain by proton magnetic resonance spectroscopy.

PURPOSE: To determine whether extensive use of mobile phones affects brain metabolites detectable by proton magnetic resonance spectroscopy (1H MRS). MATERIALS AND METHODS: Twenty-one extensive mobile phone users (average use = 5.5 +/- 2.2 years at 2.4 +/- 1.1 hours/day) and 15 control subjects were recruited and submitted to a 1H MRS brain examination at 1.5 Tesla. Data were recorded in the most exposed right temporal and pontobulbar areas as well as in the contralateral left temporal area. The ratios of N-acetylaspartate (NAA), choline (Cho) and myo-inositol (mI) to creatine/phosphocreatine (Cr) were measured. RESULTS: No statistically significant changes in the NAA/Cr, Cho/Cr and mI/Cr ratios were measured between mobile phone users and control subjects and between the exposed and contralateral temporal areas. CONCLUSION: These results indicate that extensive exposition to mobile phone radiation does not cause MRS-detectable brain metabolic changes.

Adult↗
PubMed2004

Failure of valacyclovir for herpes zoster in a moderately immunocompromised HIV-infected patient.

Whereas valacyclovir is widely used and is recommended by some authors in moderately immunocompromised HIV-infected patients, its use has not been validated by clinical studies. We report a case of herpes zoster in an HIV-infected patient for whom neurologic complication was not avoided despite valacyclovir therapy. Clinical outcome was favorable after intravenous acyclovir. This case suggests careful monitoring of valacyclovir in HIV-infected patients is necessary.

AIDS-Related Opportunistic Infections↗
PubMed2002

[Tuberculosis and HIV in Bangui, Central African Republic: strong prevalence and management difficulties].

The increasing incidence of tuberculosis in relation with the HIV-AIDS epidemic poses a major public health problem in sub-Saharan Africa. The purpose of this retrospective study was to analyze the prevalence of HIV-1 infection, clinical presentation, and bacteriological findings in patients treated for tuberculosis in a hospital department in Bangui, Central African Republic between January 1996 and December 1998. Among the 1142 patients who benefited for HIV serology, HIV-1 prevalence of was 82% (IC95%: 79-85%). Most patients (92%), had not undergone HIV serology before hospitalization. Mean age was 34 years. Sex ratio F/M was 1.21. Diagnosis of tuberculosis was based mainly on clinical and radiological data. Positive sputum smears were available for only 52% of the patients. The most frequent site of tuberculosis was the lungs with no significant difference between the HIV-positive and HIV-negative groups (83% versus 79% respectively). Sputum-smear examination was positive in 42% of the patients with no significant difference between the HIV-positive and HIV-negative groups (43% versus 37%). Upon admission patients usually presented advanced disease, with 11% dying within a week after hospitalization. There was a steep increase in the prevalence of HIV in tuberculosis-infected patients in Banqui, from 32% in 1988 to 62% in 1994. In spite of the existence of a National Tuberculosis Control Program, diagnostic facilities remain limited and diagnosis of tuberculosis and HIV-infection is often delayed. Outpatient care must be improved.

Adult↗
PubMed2001

Clinical and virologic characterization of acyclovir-resistant varicella-zoster viruses isolated from 11 patients with acquired immunodeficiency syndrome.

We studied the clinical resistance to acyclovir of infections with varicella-zoster viruses (VZV) in patients with acquired immunodeficiency syndrome, and we correlated it to virologic analyses. Eleven patients with VZV infections (treated with acyclovir, 30 mg/kg/day, given intravenously, or 4 g/day, given orally) were included in the study because of the failure of 10 days of acyclovir therapy. Susceptibility of VZV isolates to acyclovir was tested using a plaque reduction assay to determine the 50% inhibitory concentration (IC(50)) of acyclovir and the SI(50) (IC(50) of the patient isolate/IC(50) of the reference strain) to acyclovir. The thymidine kinase (TK) gene, which supports the resistance, was sequenced on amplified products. Only 3 patients had a significant increase in the IC(50), as compared with the IC(50) of the reference strain (SI(50) of > or =4), and a mutation in the TK gene. For the other 8 patients, the clinical resistance was not confirmed by the virologic results: the SI(50) was < 4, and no mutation was detected in the TK gene. Because no acyclovir-resistant strain appeared during a shorter period of time, we suggest an increase in the duration of the treatment to 21 days before acyclovir resistance is suspected.

Acyclovir↗
PubMed2001

CCK and development of mother preference in sheep: a neonatal time course study.

We investigated the effects of a CCK-A receptor antagonist on the development of mother preference. Lambs received 2-NAP either at birth or 6, or 12 h later. Controls were given saline. When tested at 24 h of age, lambs receiving 2-NAP at birth or 6 h later did not display mother preference unlike controls and lambs which were given 2-NAP at 12 h. The effect of the antagonist persisted at 48 h of age in lambs treated at birth. This suggests that endogenous CCK participates in the development of mother preference only in the first few hours following birth.

Animals↗
PubMed2001

Genome sequence and comparative analysis of the solvent-producing bacterium Clostridium acetobutylicum.

The genome sequence of the solvent-producing bacterium Clostridium acetobutylicum ATCC 824 has been determined by the shotgun approach. The genome consists of a 3.94-Mb chromosome and a 192-kb megaplasmid that contains the majority of genes responsible for solvent production. Comparison of C. acetobutylicum to Bacillus subtilis reveals significant local conservation of gene order, which has not been seen in comparisons of other genomes with similar, or, in some cases closer, phylogenetic proximity. This conservation allows the prediction of many previously undetected operons in both bacteria. However, the C. acetobutylicum genome also contains a significant number of predicted operons that are shared with distantly related bacteria and archaea but not with B. subtilis. Phylogenetic analysis is compatible with the dissemination of such operons by horizontal transfer. The enzymes of the solventogenesis pathway and of the cellulosome of C. acetobutylicum comprise a new set of metabolic capacities not previously represented in the collection of complete genomes. These enzymes show a complex pattern of evolutionary affinities, emphasizing the role of lateral gene exchange in the evolution of the unique metabolic profile of the bacterium. Many of the sporulation genes identified in B. subtilis are missing in C. acetobutylicum, which suggests major differences in the sporulation process. Thus, comparative analysis reveals both significant conservation of the genome organization and pronounced differences in many systems that reflect unique adaptive strategies of the two gram-positive bacteria.

Amino Acid Sequence↗
PubMed2001

Photoperiod and temperature interactions regulate low-temperature-induced gene expression in barley.

Vernalization and photoperiod (PP) responses are developmental mechanisms that allow plants to synchronize their growth and reproductive cycles with the seasonal weather changes. Vernalization requirement has been shown to influence the length of time that low-temperature (LT)-induced genes are up-regulated when cereal species are exposed to acclimating temperatures. The objective of the present study was to determine whether expression of LT-induced Wcs and Wcor gene families is also developmentally regulated by PP response. The LT-tolerant, highly short-day (SD)-sensitive barley (Hordeum vulgare L. cv Dicktoo) was subjected to 8-h SD and 20-h long-day PPs at cold-acclimating temperatures over a period of 70 d. A delay in transition from the vegetative to the reproductive stage under SD resulted in an increased level and longer retention of LT tolerance. Similar WCS and WCOR protein homologs were expressed, but levels of expression were much higher in plants acclimated under SD, indicating that the poor LT tolerance of long-day plants was the result of an inability to maintain LT-induced genes in an up-regulated state. These observations indicate that the PP and vernalization genes influence the expression of LT-induced genes in cereals through separate pathways that eventually converge to activate genes controlling plant development. In both instances, the delay in the transition from the vegetative to the reproductive stage produces increased LT tolerance that is sustained for a longer period of time, indicating that the developmental genes determine the duration of expression of LT-induced structural genes.

Acclimatization↗
PubMed2001

Contraceptive security, information flow, and local adaptations: family planning Morocco.

BACKGROUND: Many developing countries increasingly recognize and acknowledge family planning as a critical part of socio-economic development. However, with few health dollars to go around, countries tend to provide essential drugs for curative care, rather than for family planning products. Donors have historically provided free contraceptives for family planning services. Whether products are donated or purchased by the country, a successful family planning program depends on an uninterrupted supply of products, beginning with the manufacturer and ending with the customer. Any break in the supply chain may cause a family planning program to fail. A well-functioning logistics system can manage the supply chain and ensure that the customers have the products they need, when they need them. METHODOLOGY: Morocco was selected for the case study. The researchers had ready access to key informants and information about the Logistics Management Information System. Because the study had time and resource constraints, research included desktop reviews and interview, rather than data collection in the field. RESULTS: The case study showed that even in a challenging environment an LMIS can be successfully deployed and fully supported by the users. It is critical to customize the system to a country-specific situation to ensure buy-in for the implementation. CONCLUSIONS: Significant external support funding and technical expertise are critical components to ensure the initial success of the system. Nonetheless, evidence from the case study shows that, after a system has been implemented, the benefits may not ensure its institutionalization. Other support, including local funding and technical expertise, is required.

Contraceptive Agents↗
PubMed2000

Herpes zoster.

Explore the source record for details and available documents.

Acquired Immunodeficiency Syndrome↗
PubMed2000

Biotechnological applications of plant freezing associated proteins.

Plants use a wide array of proteins to protect themselves against low temperature and freezing conditions. The identification of these freezing tolerance associated proteins and the elucidation of their cryoprotective functions will have important applications in several fields. Genes encoding structural proteins, osmolyte producing enzymes, oxidative stress scavenging enzymes, lipid desaturases and gene regulators have been used to produce transgenic plants. These studies have revealed the potential capacity of different genes to protect against temperature related stresses. In some cases, transgenic plants with significant cold tolerance have been produced. Furthermore, the biochemical characterization of the cold induced antifreeze proteins and dehydrins reveals many applications in the food and the medical industries. These proteins are being considered as food additives to improve the quality and shelf-life of frozen foods, as cryoprotective agents for organ and cell cryopreservation, and as chemical adjuvant in cancer cryosurgery.

Adaptation, Biological↗
PubMed2000

Two novel intrinsic annexins accumulate in wheat membranes in response to low temperature.

Four immunologically related proteins that belong to the annexin family were identified in cold acclimated wheat (Triticum aestivum). Two soluble forms with molecular masses of 34 and 36 kDa were found to bind phospholipid membranes in a calcium-dependent manner. These two forms are similar to the previously reported doublet in several plant species. The other two forms, with molecular masses of 39 and 22.5 kDa, were found associated with the microsomal fraction. Biochemical analysis showed that both forms are intrinsic membrane proteins and their association with the membrane is calcium independent. This is, to our knowledge, the first report of the presence of these annexin forms in plants. Membrane purification by two phase partitioning demonstrated that the p39 form is localized to the plasma membrane. Immunoblot analysis showed that the protein level of both p39 and p22.5 increases gradually reaching a maximum level after one day of low temperature exposure. The protein accumulation was similar in both hardy and less hardy cultivars, suggesting that the accumulation is not correlated with freezing tolerance. The results are discussed with respect to the possible role of these new intrinsic membrane annexins in low temperature signal transduction pathway.

Annexins↗
PubMed1999

Differentiating lumbar disc protrusions, disc bulges, and discs with normal contour but abnormal signal intensity. Magnetic resonance imaging with discographic correlations.

STUDY DESIGN: Independent evaluation by two observers of 132 lumbar discs in 45 patients with chronic low back pain investigated by both magnetic resonance imaging and discography. OBJECTIVES: To assess some of the fundamental differences between lumbar disc protrusions, disc bulges, and discs with normal contour but abnormal signal intensity on T2-weighted magnetic resonance images. SUMMARY OF BACKGROUND DATA: Moderate interobserver agreement has been reported when the morphologic terms normal, bulge, protrusion, and extrusion are used. The validity of this nomenclature remains unknown. METHODS: Discs were evaluated on magnetic resonance images for central and peripheral signal characteristics, height, contour, and nerve root compression. Discograms were classified according to degrees of disc degeneration, disruption, and pain reproduction. RESULTS: Loss of intervertebral height or abnormal signal intensity on magnetic resonance imagery was significantly associated with disc disruptions extending into or beyond the outer anulus on discograms. All 23 protrusions (100%) and 12 of 15 disc bulges (80%) were associated with Stage 2 or 3 anular disruptions and, in most instances, similar or exact reproduction of pain during disc injection. There was no significant difference between disc protrusions, disc bulges, and discs with normal contour but abnormal signal, with respect to degree of disc degeneration, extent of disruptions, or presence of discogenic pain. CONCLUSIONS: In patients with chronic low back pain, loss of disc height or abnormal signal intensity is highly predictive of symptomatic tears extending into or beyond the outer anulus. Disc bulges and disc protrusions do not represent discs with significantly different internal architecture, based on the findings of discography, and are no more suggestive of symptomatic tears than discs showing normal contour but decreased height or abnormal signal intensity.

Adult↗
PubMed1998

Acyclovir-resistant herpes zoster in human immunodeficiency virus-infected patients: results of foscarnet therapy.

We retrospectively studied 18 consecutive cases of acyclovir-resistant zoster. All the patients had chronic skin lesions that failed to heal despite treatment with intravenous acyclovir (30 mg/[kg.d]) in 15 cases and oral acyclovir (4 g/d) in three cases for > 10 days. The mean CD4+ cell count was 20 x 10(6)/L. The mean number of previous zoster episodes was 1.53. Fifteen of the 16 patients evaluable for previous acyclovir treatment had received the drug. Thirteen patients were treated with intravenous foscarnet (200 mg/[kg.d]) for a mean of 17.8 days. Complete healing was observed in 10 (77%) of the 13 treated patients. Zoster relapsed after cessation of foscarnet therapy in five of the 10 responding patients. The median time to relapse was 110 days. Four patients died of varicella-zoster virus-associated visceral complications. These results show that acyclovir-resistant zoster has a poor prognosis but responds well to foscarnet therapy.

AIDS-Related Opportunistic Infections↗
PubMed1997

Multiplex sequencing of 1.5 Mb of the Mycobacterium leprae genome.

The nucleotide sequence of 1.5 Mb of genomic DNA from Mycobacterium leprae was determined using computer-assisted multiplex sequencing technology. This brings the 2.8-Mb M. leprae genome sequence to approximately 66% completion. The sequences, derived from 43 recombinant cosmids, contain 1046 putative protein-coding genes, 44 repetitive regions, 3 tRNAs, and 15 tRNAs. The gene density of one per 1.4 kb is slightly lower than that of Mycoplasma (1.2 kb). Of the protein coding genes, 44% have significant matches to genes with well-defined functions. Comparison of 1157 M. leprae and 1564 Mycobacterium tuberculosis proteins shows a complex mosaic of homologous genomic blocks with up to 22 adjacent proteins in conserved map order. Matches to known enzymatic, antigenic, membrane, cell wall, cell division, multidrug resistance, and virulence proteins suggest therapeutic and vaccine targets. Unusual features of the M. leprae genome include large polyketide synthase (pks) operons, inteins, and highly fragmented pseudogenes.

Amino Acid Sequence↗
PubMed1996

[Treatment of cytomegalovirus infections in HIV infection].

Cytomegalovirus (CMV) infections are common in patients with AIDS. Retinal localizations predominate, although digestive and neurological and more rarely pulmonary localizations are sometimes seen. Functional prognosis is poor in case of retinal infection requiring early treatment. Standard therapy is based on intravenous administration of two antiviral agents with similar actions: ganciclovir and foscarnet. Maintenance therapy, aimed at delaying recurrence, is clearly indicated for retinitis and may be so for other localizations. The parenteral route is recommended although in case of contraindications, oral ganciclovir and local treatments (intravitreal injections, intravireal implants) may be used. Recurrence is observed earlier after oral treatment, local treatments cannot prevent other localizations and retinal detachment is more frequent with vitreal implants. Other drugs are under study. Cygalovir would be an interesting alternative due to its long half-life allowing fewer injections. Primary prophylaxy for CMV infection is an important perspective. Quantitative PCR will help better define risk groups of patients who could benefit from preventive therapy. The choice between oral or intravenous administration and the correct dose remain to be determined for the most effective preventive treatment and to avoid the emergence of resistance.

AIDS-Related Opportunistic Infections↗