Coexpression of virulence and fosfomycin susceptibility in Listeria: molecular basis of an antimicrobial in vitro-in vivo paradox

Discrepancies between resistance in vitro and therapeutic efficacy in vivo are generally attributed to failure of laboratory susceptibility tests to reflect an antibiotic's pharmacokinetic or pharmacodynamic properties. We show here that this phenomenon can result from differential in vitro-in vivo expression of bacterial determinants of antibiotic susceptibility. We found that an in vivo-induced virulence factor, Hpt, also mediates uptake of fosfomycin in Listeria monocytogenes. These bacteria therefore seem resistant to fosfomycin in vitro, although they are in fact susceptible to the antibiotic during infection.     

Cardiovascular risk of young growth-hormone-deficient adolescents. Differences in growth-hormone-treated and untreated patients

OBJECTIVE: To determine whether postprandial lipids, coagulation factors and homocysteine levels are abnormal in young growth hormone (GH)-deficient (GHD) adolescents. METHODS: Fifteen GHD adolescents on GH replacement were studied. Ten untreated GHD adolescents and 15 healthy subjects served as controls. Fasting lipids, lipoprotein(a), fibrinogen, plasminogen activator inhibitor-1, homocysteine, folate and vitamin B12 levels were measured. Cholesterol and triglycerides were measured 4 h after a high fat meal. RESULTS: Fasting and postprandial triglycerides and homocysteine levels of untreated GHD patients were increased compared to those of GH-treated GHD subjects and healthy controls; fibrinogen concentrations were elevated in both treated and untreated adolescents. CONCLUSIONS: GHD adolescents present an abnormal fasting and postprandial lipid profile. In addition, the increased fibrinogen and homocysteine levels are suggestive of the accumulation of cardiovascular risk factors early on in life.     

Optimization of biomass, total carotenoids and astaxanthin production in Haematococcus pluvialis Flotow strain Steptoe (Nevada, USA) under laboratory conditions

The microalga Haematococcus pluvialis Flotow is one of the natural sources of astaxanthin, a pigment widely used in salmon feed. This study was made to discover optimal conditions for biomass and astaxanthin production in H. pluvialis from Steptoe, Nevada (USA), cultured in batch mode. Growth was carried out under autotrophic (with NaNO3, NH4Cl and urea) and mixotrophic conditions (with 4, 8, 12 mM sodium acetate) under two photon flux densities (PFD) (35 and 85 mumol m-2 s-1). The carotenogenesis was induced by 1) addition of NaCl (0.2 and 0.8%), 2) N-deprivation and 3) high PFD (150 mumol m-2 s-1). Total carotenoids were estimated by spectrophotometry and total astaxanthin by HPLC. Ammonium chloride was the best N-source for growth (k = 0.7 div day-1, 228-258 mg l-1 and 2.0 x 10(5)-2.5 x 10(5) cells ml-1 at both PFD, respectively). With increasing acetate concentration, a slight increment in growth occurred only at 85 mumol m-2 s-1. Light was the best inductive carotenogenic factor, and the highest carotenoid production (4.9 mg l-1, 25.0 pg cell-1) was obtained in cultures pre-grown in nitrate at low light. The NaCl caused an increase in carotenoid content per cell at increasing salt concentrations, but resulted in a high cell mortality and did not produce any increment in carotenoid content per volume compared to cultures grown at 150 mumol m-2 s-1. The highest carotenoid content per cell (22 pg) and astaxanthin content per dry weight (10.3 mg g-1) (1% w/w) were obtained at 85 mumol m-2 s-1 with 0.8% NaCl.     

Effect of salinity on the quantity and quality of carotenoids accumulated by Dunaliella salina (strain CONC-007) and Dunaliella bardawil (strain ATCC 30861) Chlorophyta

Dunaliella salina and D. bardawil are well-known microalgae accumulating high levels of beta-carotene under growth-limiting conditions. In both taxa, this pigment is primarily composed of the isomers 9-cis and all-trans. The 9-cis beta-carotene occurs only in natural sources and is the most attractive from a commercial point of view. The conditions that enhance the preferred accumulation of 9-cis beta-carotene in D. salina are controversial and they have not been well established yet. This study examined the effect of salinity on the quantity and quality of total carotenoids and beta-carotene isomers accumulated by D. salina (strain CONC-007) and D. bardawil (strain ATCC 30861) grown in two media with different nutritional compositions (PES and ART) and at salt concentrations of 1M, 2M and 3M NaCl. Total carotenoids were determined by spectrophotometry and beta-carotene isomers, by HPLC. The highest carotenoid contents per cell were obtained at 2M NaCl in both taxa. In both media, an increase of the 9-cis/all-trans beta-carotene ratio was observed in D. bardawil when the salt concentration increased, with a maximum value of 2.6 (in ART medium at 3M NaCl). In D. salina this ratio did not exhibit the same pattern, and the salt concentrations for maximal ratios were different in both media. The highest ratio obtained for this strain was 4.3 (in ART medium at 2M NaCl).     

Olfactory sensitivity for carboxylic acids in spider monkeys and pigtail macaques

Using a conditioning paradigm, the olfactory sensitivity of four spider monkeys and four pigtail macaques for a homologous series of carboxylic acids (n-propionic acid to n-heptanoic acid) was investigated. With only few exceptions, the animals of both species significantly discriminated concentrations <1 p.p.m. from the odorless solvent and in several cases individual monkeys even demonstrated thresholds <1 p.p.b. The results showed (i). both primate species to have a well-developed olfactory sensitivity for carboxylic acids, which for some substances matches or even is markedly better than that of species such as the rat or the dog and (ii). a significant correlation between perceptibility in terms of olfactory detection thresholds and carbon chain length of the carboxylic acids in both species tested. These findings lend further support to the growing body of evidence suggesting that between-species comparisons of the number of functional olfactory receptor genes or of neuroanatomical features are poor predictors of olfactory performance, and that general labels such as 'microsmat' or 'macrosmat'-which usually are based on allometric comparisons of olfactory brain structures-are inadequate to describe a species' olfactory capabilities.     

Effectiveness of multiple-site EMG biofeedback in the reduction of arousal

During the training phase, 36 subjects received (a) EMG biofeedback from multiple muscle sites, (b) EMG biofeedback from the frontal site, or (c) no biofeedback. Results indicated that neither biofeedback procedure reduced self-reports of anxiety, but that multiple-site biofeedback was effective in reducing several indices of autonomic arousal (pulse rate, finger pulse volume, and skin temperature) while frontal biofeedback was not. During the generalization/stress phase, all subjects were threatened with and received electric shocks and were told to apply the relaxation techniques they learned during the training phase even though no additional biofeedback would be provided. Results indicated that multiple-site biofeedback was effective in reducing self-reports of anxiety and autonomic arousal but that frontal biofeedback was not. These results confirm previous data indicating that frontal biofeedback is not an effective procedure for controlling stress, but suggest that EMG biofeedback can be effective in reducing self-reported anxiety and autonomic arousal if a multiple muscle-site feedback procedure is employed.     

Comparison of ITS RFLP patterns of Gracilaria (Rhodophyceae, Gracilariales) populations from Chile and New Zealand and an examination of interfertility of Chilean morphotypes

Restriction fragment length polymorphism (RFLP) patterns of the internal transcribed spacer (ITS) of the nuclear ribosomal cistron and crossability trials were used to characterize four morphotypes of Gracilaria from Lenga, Isla Santa María and Maullín, Chile, and two morphotypes from sites in New Zealand. PCR products from all Chilean morphotypes resulted in a major single band of ca. 1198 bp. ITS-RFLP profiles generated with the restriction enzymes Cla I, Hae III, Pst I, Hha I, Rsa I and Taq I, were identical in all cases. All crosses within, as well as between, morphotypes resulted in cystocarp differentiation, with the production of viable carpospores. Based upon these data, it is concluded that the four morphotypes from Chile correspond to a single species, G. chilensis, and that the ITS-RFLP pattern is a useful marker to predict genetic relatedness at the specific level in Gracilaria. A comparison of the ITS-RFLP patterns of the Chilean morphotypes with the patterns of two samples of G. chilensis from New Zealand revealed that the sample from Scorching Bay, Wellington, fits the Chilean ITS-RFLP patterns. The population from Blockhouse Bay, Auckland, appears to correspond to another species. This revised version was published online in July 2006 with corrections to the Cover Date.     

New potent imidazoisoquinolinone derivatives as anti-Trypanosoma cruzi agents: Biological evaluation and structure–activity relationships

A series of novel benzoimidazo and N-aryl-5-oxo-imidazo[1,2-b]isoquinoline-10-carbothioamides was developed. All the compounds were evaluated for their in vitro action against the epimastigote form of Trypanosoma cruzi. Four of them showed higher activity than Nifurtimox. Their unspecific cytotoxicity was evaluated using HeLa and L6 cells, being non-toxic at concentrations at least 15 and 200 times higher than that of T. cruzi IC_50. To gain insight into the mechanism of action, their DNA binding properties and reactivity with glutathione were studied, and QSAR study was performed.