Diffusion of Ofloxacin in the Endocarditis Vegetation Assessed with Synchrotron Radiation UV Fluorescence Microspectrocopy

The diffusion of antibiotics in endocarditis vegetation bacterial masses has notbeen described, although it may influence the efficacy of antibiotic therapy inendocarditis. The objective of this work was to assess the diffusion ofofloxacin in experimental endocarditis vegetation bacterial masses usingsynchrotron-radiation UV fluorescence microspectroscopy. Streptococcalendocarditis was induced in 5 rabbits. Three animals received an unique IVinjection of 150 mg/kg ofloxacin, and 2 control rabbits were left untreated. Twofluorescence microscopes were coupled to a synchrotron beam for excitation at275 nm. A spectral microscope collected fluorescence spectra between 285 and 550nm. A second, full field microscope was used with bandpass filters at510–560 nm. Spectra of ofloxacin-treated vegetations presented higherfluorescence between 390 and 540 nm than control. Full field imaging showed thatofloxacin increased fluorescence between 510 and 560 nm. Ofloxacin diffused intovegetation bacterial masses, although it accumulated in their immediateneighborhood. Fluorescence images additionally suggested an ofloxacinconcentration gradient between the vegetation peripheral and central areas. Inconclusion, ofloxacin diffuses into vegetation bacterial masses, but itaccumulates in their immediate neighborhood. Synchrotron radiation UVfluorescence microscopy is a new tool for assessment of antibiotic diffusion inthe endocarditis vegetation bacterial masses.     

Initiation of insulin therapy in elderly patients taking oral antidiabetes drugs

Background

We sought to estimate the rate of initiation of insulin therapy among elderly patients using oral anti-diabetes drugs and to identify the factors associated with this initiation.

Methods

We conducted a population-based cohort study involving people aged 66 or more years who were newly dispensed an oral antidiabetes drug. Individuals who had received acarbose or a thiazolidinedione were excluded. The rate of insulin initiation was calculated by use of the Kaplan–Meier method. Factors associated with insulin initiation were identified by multivariable Cox regression analyses.

Results

In this cohort of 69 674 new users of oral antidiabetes drugs, insulin was initiated at rate of 9.7 cases per 1000 patient-years. Patients who had initially received an insulin secretagogue (rather than metformin), who were prescribed an oral antidiabetes drug by an endocrinologist or an internist, who received higher initial doses of an oral antidiabetes drug, who received oral corticosteroids, used glucometer strips, or were admitted to hospital in the year before initiation of oral antidiabetes therapy, or who received 16 or more medications were more likely than those without these characteristics to have insulin therapy initiated. In contrast, patients who received thiazides or who used up to 12 medications (v. none) were less likely to have insulin therapy initiated.

Interpretation

Several factors related to drugs and health services are associated with the initiation of insulin therapy in elderly patients receiving oral antidiabetes drugs. It is unclear whether these factors predict secondary failure of oral antidiabetes drugs or instead reflect better management of type 2 diabetes.Type 2 diabetes is a progressive disease that requires ongoing increases in doses and complexity of hypo-glycemic pharmacotherapy.¹ Although insulin may be the first agent prescribed to patients with type 2 diabetes who have marked hyperglycemia, oral antidiabetes drugs are usually the first pharmacologic treatment. In general, these drugs are first prescribed as monotherapy; however, combination therapy with 2 oral antidiabetes drugs with different mechanisms may also be a first-line option.^2–4 Unfortunately, oral antidiabetes drugs have limited efficacy for long-term glucose lowering^1,5 and, therefore, many patients may require insulin to achieve better metabolic control.⁶There are several factors that may account for the need to initiate insulin therapy in patients taking oral antidiabetes drugs, including progressive β-cell failure,⁷ deterioration of insulin sensitivity because of glucose toxicity or the development of resistance to the oral antidiabetes drug.^8,9 Disease severity, a younger age at diagnosis^1,10 and poor adherence to treatment may also lead to poor metabolic control in patients with diabetes.¹¹Our study included an outpatient population of elderly patients, all of whom were new users of an oral antidiabetes drug. We sought to estimate the rate of initiation of insulin therapy and to identify factors associated with initiation of insulin therapy.     

LKB1 as a Gatekeeper of Hepatocyte Proliferation and Genomic Integrity during Liver Regeneration

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Progressive Cognitive Deficit,Motor Impairment and Striatal Pathology in a Transgenic Huntington Disease Monkey Model from Infancy to Adulthood

One of the roadblocks to developing effective therapeutics for Huntington disease (HD) is the lack of animal models that develop progressive clinical traits comparable to those seen in patients. Here we report a longitudinal study that encompasses cognitive and motor assessment, and neuroimaging of a group of transgenic HD and control monkeys from infancy to adulthood. Along with progressive cognitive and motor impairment, neuroimaging revealed a progressive reduction in striatal volume. Magnetic resonance spectroscopy at 48 months of age revealed a decrease of N-acetylaspartate (NAA), further suggesting neuronal damage/loss in the striatum. Postmortem neuropathological analyses revealed significant neuronal loss in the striatum. Our results indicate that HD monkeys share similar disease patterns with HD patients, making them potentially suitable as a preclinical HD animal model.     

Mechanisms of antimicrobial peptide action: studies of indolicidin assembly at model membrane interfaces by in situ atomic force microscopy

We report here on an in situ atomic force microscopy study of the interaction of indolicidin, a tryptophan-rich antimicrobial peptide, with phase-segregated zwitterionic DOPC/DSPC supported planar bilayers. By varying the peptide concentration and bilayer composition through the inclusion of anionic lipids (DOPG or DSPG), we found that indolicidin interacts with these model membranes in one of two concentration-dependent manners. At low peptide concentrations, indolicidin forms an amorphous layer on the fluid domains when these domains contain anionic lipids. At high peptide concentrations, indolicidin appears to initiate a lowering of the gel-phase domains independent of the presence of an anionic lipid. Similar studies performed using membrane-raft mimetic bilayers comprising 30mol% cholesterol/1:1 DOPC/egg sphingomyelin revealed that indolicidin does not form a carpet-like layer on the zwitterionic DOPC domains at low peptide concentrations and does not induce membrane lowering of the liquid-ordered sphingomyelin/cholesterol-rich domains at high peptide concentration. Simultaneous AFM-confocal microscopy imaging did however reveal that indolicidin preferentially inserts into the fluid-phase DOPC domains. These data suggest that the indolicidin-membrane association is influenced greatly by specific electrostatic interactions, lipid fluidity, and peptide concentration. These insights provide a glimpse into the mechanism of the membrane selectivity of antibacterial peptides and suggest a powerful correlated approach for characterizing peptide-membrane interactions.     

Increased REM sleep associated with melatonin deficiency after pinealectomy: a case study

The objectives of the investigation were to assess hypersomnia, which progressively appeared in a young patient after a pinealectomy, chemotherapy, and radiotherapy for a typical germinoma, as well as the potential benefit of melatonin administration in the absence of its endogenous secretion. 24 h ambulatory polysomnography and the Multiple Sleep Latency Test (MSLT) were performed; in addition, daily plasma melatonin, cortisol, growth hormone, prolactin, and rectal temperature profiles were determined before and during melatonin treatment (one 2 mg capsule given nightly at 21:00 h for 4 weeks). MSLT showed abnormal sleep latency and two REM sleep onsets. Nighttime total sleep duration was lengthened, mainly as a consequence of an increased REM sleep duration. These parameters were slightly modified by melatonin replacement. Plasma melatonin levels, which were constantly nil in the basal condition, were increased to supraphysiological values with melatonin treatment. The plasma cortisol profile showed nycthemeral variation within the normal range, and the growth hormone profile showed supplementary diurnal peaks. Melatonin treatment did not modify the secretion of either hormone. The plasma prolactin profile did not display a physiological nocturnal increase in the basal condition; however, it did during melatonin treatment, with the rise coinciding with the nocturnal peak of melatonin concentration. A 24 h temperature rhythm of normal amplitude was persistent, though the mean level was decreased and the rhythm was dampened during melatonin treatment. The role of radiotherapy on the studied parameters cannot be excluded; the findings of this case study suggest that the observed hypersomnia is not the result of melatonin deficiency alone. Overall, melatonin treatment was well tolerated, but the benefit on the sleep abnormality, especially on daytime REM sleep, was minor, requiring the re-introduction of modafinil treatment.     

Multifunctional acetyl-CoA carboxylase 1 is essential for very long chain fatty acid elongation and embryo development in Arabidopsis

Acetyl-CoA carboxylase (ACCase) catalyses the carboxylation of acetyl-CoA, forming malonyl-CoA, which is used in the plastid for fatty acid synthesis and in the cytosol in various biosynthetic pathways including fatty acid elongation. In Arabidopsis thaliana, ACC1 and ACC2, two genes located in a tandem repeat within a 25-kbp genomic region near the centromere of chromosome 1, encode two multifunctional ACCase isoforms. Both genes, ACC1 and ACC2, appear to be ubiquitously expressed, but little is known about their respective function and importance. Here, we report the isolation and characterisation of two allelic mutants disrupted in the ACC1 gene. Both acc1-1 and acc1-2 mutations are recessive and embryo lethal. Embryo morphogenesis is impaired and both alleles lead to cucumber-like structures lacking in cotyledons, while the shortened hypocotyl and root exhibit a normal radial pattern organisation of the body axis. In this abnormal embryo, the maturation process still occurs. Storage proteins accumulate normally, while triacylglycerides (TAG) are synthesised at a lower concentration than in the wild-type seed. However, these TAG are totally devoid of very long chain fatty acids (VLCFA) and consequently enriched in C18:1, like all lipid fractions analysed in the mutant seed. These data demonstrate, in planta, the role of ACCase 1 in VLCFA elongation. Furthermore, this multifunctional enzyme also plays an unexpected and central function in embryo morphogenesis, especially in apical meristem development.     

Evidence for linkage of a new region (11p14) to eczema and allergic diseases

Asthma, allergic rhinitis (AR) and atopic dermatitis also called eczema are allergic co-morbidites, which are likely to depend on pleiotropic genetic effects as well as on specific genetic factors. After a previous genome-wide linkage screen conducted for asthma and AR in a sample of 295 French EGEA families ascertained through asthmatic subjects, the aim here was to search for genetic factors involved in eczema and more particularly the ones shared by the three allergic diseases using the same EGEA data. In this sake, eczema and phenotypes of “allergic disease” accounting for the joint information on the presence/absence of the three diseases were examined by linkage analyses using the maximum likelihood binomial method. A fine mapping was carried out in regions detected for potential linkage, followed by association studies using the family-based association test (FBAT). Evidence for linkage to 11p14 region was shown for “allergic disease” and eczema. Linkage was also indicated between eczema and 5q13 and between “allergic disease” and both 5p15 and 17q21 regions. Fine mapping supported the evidence of linkage to 11p14 and FBAT analyses showed the association between “allergic disease” and a marker located at the linkage peak on 11p14. Further investigations in this region will allow identifying genetic factor(s) which could have pleiotropic effect in the three allergic diseases.