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Summary The lack of proper treatment for serious infectious diseases due to the emergence of multidrug resistance reinforces the need for the discovery of novel antibiotics. This is particularly true for tuberculosis (TB) for which 3.7% of new cases and 20% of previously treated cases are estimated to be caused by multi-drug resistant strains. In addition, in the case of TB, which claimed 1.5 million lives in 2014, the treatment of the least complicated, drug sensitive cases is lengthy and disagreeable. Therefore, new drugs with novel targets are urgently needed to control resistant Mycobacterium tuberculosis strains. In this manuscript we report the characterization of the thiopeptide micrococcin P1 as an anti-tubercular agent. Our biochemical experiments show that this antibiotic inhibits the elongation step of protein synthesis in mycobacteria. We have further identified micrococcin resistant mutations in the ribosomal protein L11 (RplK); the mutations were located in the proline loop at the N-terminus. Reintroduction of the mutations into a clean genetic background, confirmed that they conferred resistance, while introduction of the wild type RplK allele into resistant strains re-established sensitivity. We also identified a mutation in the 23S rRNA gene. These data, in good agreement with previous structural studies suggest that also in M. tuberculosis micrococcin P1 functions by binding to the cleft between the 23S rRNA and the L11 protein loop, thus interfering with the binding of elongation factors Tu and G (EF-Tu and EF-G) and inhibiting protein translocation. [ABSTRACT FROM AUTHOR]

Estimation of pesticide volatilization from plants is difficult because of our poor understanding of foliar penetration by pesticides, which governs the amount of pesticide available for volatilization from the leaf surface. The description of foliar penetration is still incomplete because experimental measurements of this complex process are difficult. In this study, the dynamics of leaf penetration of 14C-chlorothalonil and 14C-epoxiconazole applied to wheat leaves were measured in a volatilization chamber, which allowed us to simultaneously measure pesticide volatilization. Fungicide penetration into leaves was characterized using a welldefined sequential extraction procedure distinguishing pesticide fractions residing at different foliar compartments; this enabled us to accurately measure the penetration rate constant into the leaves. The effect of pesticide formulation was also examined by comparing formulated and pure epoxiconazole. We observed a strong effect of formulation on leaf penetration in the case of a systemic product. Furthermore, the penetration rate constant of formulated epoxiconazole was almost three times that of pure epoxiconazole (0.47 ± 0.20 and 0.17 ± 0.07, respectively). Our experimental results showed high recovery rates of the radioactivity applied within the range of 90.5 to 105.2%. Moreover, our results confirm that pesticide physicochemical properties are key factors in understanding leaf penetration of pesticide and its volatilization. This study provides important and useful parameters for mechanistic models describing volatilization of fungicides applied to plants, which are scarce in the literature. [ABSTRACT FROM AUTHOR]

Summary: Trans-translation is a key process in bacteria which recycles stalled ribosomes and tags incomplete nascent proteins for degradation. This ensures the availability of ribosomes for protein synthesis and prevents the accumulation of dysfunctional proteins. The tmRNA, ssrA, is responsible for both recovering stalled ribosomes and encodes the degradation tag; ssrA associates and functions with accessory proteins such as SmpB. Although ssrA and smpB are ubiquitous in bacteria, they are not essential for the viability of many species. The Mycobacterium tuberculosis genome has homologues of both ssrA and smpB. We demonstrated that ssrA is essential in M. tuberculosis, since the chromosomal copy of the gene could only be deleted in the presence of a functional copy integrated elsewhere. However, we were able to delete the proteolytic tagging function by constructing strains carrying a mutant allele (ssrA DD ). This demonstrates that ribosome rescue by ssrA is the essential function in M. tuberculosis, SmpB was not required for aerobic growth, since we were able to construct a deletion strain. However, the smpBΔ strain was more sensitive to antibiotics targeting the ribosome. Strains with deletion of smpB or mutations in ssrA did not show increased sensitivity (or resistance) to pyrazinamide suggesting that this antibiotic does not directly target these components of the tmRNA tagging system. [Copyright &y& Elsevier]

The article presents a case study of an adult female hedgehog (Erinaceus europaeus) detected with injured, presumably from vehicular trauma. It states that clinical and radiographic examination under general anesthesia of hedgehog showed a lateral elbow luxation. Information on the usage of surgical approach with circumferential suture prostheses to stabilize the elbow is also presented.

This study investigated the impacts of extensive and semi-intensive green roofs on both building insulation and surface urban heat island effect under winter conditions. To this aim we compared measurements of surface and building envelope temperatures as well as conductive heat fluxes reaching the external building envelope with those measured on a conventional bituminous roof under identical climatic conditions. The main effect of green roofs was to decrease daily fluctuations of external building envelope temperatures and as a consequence to reduce fluctuations of conductive heat fluxes reaching the building envelope. This effect is all the more important that the substrate is deep, in link with its heat capacity and thermal inertia. Yet, no significant effect of the green roofs on surface urban heat island has been observed on average despite a surface cooling during daytime. It is concluded that the green roofs can be suitable urban greening solutions since they do not have negative effect on surface urban heat island during winter, provide cooling during summer, and contribute to building insulation inducing therefore building energy savings. • Conventional, extensive and semi-intensive green roofs have been compared. • Green roofs reduced temperature and heat flux fluctuations at the building surface. • Deeper substrates reduced the temperature and heat flux fluctuations of the building surface. • On average there was no or only slight effects on winter surface urban heat island. [ABSTRACT FROM AUTHOR]

Background: Individuals may be homozygous (SS) or heterozygous (AS) sickle cell gene carriers or have normal adult haemoglobin (AA). Haemoglobin S could have a protective role against malaria but evidence is sparse and the operating mechanisms are poorly known.Methods: We followed two cohorts of children. The first was enrolled at birth (156 newborn babies) and the second at 24-36 months old (84 children). Both cohorts were followed for 30 months; monthly for parasitological data and half yearly for immunological data.Results: In the first cohort, 22%, and in the second 13% of children were AS. Whatever their age parasite prevalence rates were similar in AA and AS individuals. Mean parasite densities increased less rapidly with age in AS than in AA children, and were significantly lower in AS than in AA children >48 months old. The AA children tended to be more often admitted to hospital than AS children (22% versus 11%, NS). Both anti-Plasmodium falciparum and anti-Pfl55/RESA antibody rates increased more rapidly in AA than in AS children. Conversely, the prevalence rate of cellular responders to the Pfl55/RESA antigen was similar in AA and AS children during the first 2 years of life, then it was higher in AS than in AA children.Conclusions: Sickle cell trait related antimalarial protection varies with age. The role of the modifications of the specific immune response to P. falciparum in explaining the protection of AS children against malaria is discussed. [ABSTRACT FROM AUTHOR]

Examines the age-related efficacy of chloroquine and amodiaquine to Plasmodium falciparum in South Cameroon. Resistance of Plasmodium falciparum towards chloroquine; Overall prevalence of chloroquine resistance of Plasmodium falciparum; Modification of the antimalarial efficacy of the drug by the immune status of the host.

Naturally acquired immunity to Plasmodium falciparum is related to immune system that changes during normal development and ageing. The effects of repeated infections during the early life on the maturation of the immune system are still unknown. Elucidation of these effects is of considerable interest given that malaria originates high mortality, especially during the first years of life. We conducted a cohort study to identify naturally acquired immune responses to P. falciparum. Cellular responses of Cameroonian neonates from birth to 36 months of age were evaluated every 6 months by cell proliferation and cytokines (IFN-gamma, IL-2 and IL-4) production after in vitro culture in the presence of schizont extract and Pf155/RESA peptides. Data were analyzed by a multiple correspondence analysis (MCA) exhibiting three main findings. Firstly, the lack of time-dependant evolution of specific immune pathways recruitment in the response to a given antigen, no antigen inducing a specific mode of response at a given time-point. Secondly, most of the data variability was expressed by IFN-gamma and IL-4 productions, and the major variation of the immune response with age involved this change in IFN-gamma production. Thirdly, the age-related immune response evolution is characterized by the acquisition of the capacity to mount a IFN-gamma response, a transient phase during which children produce a high IL-4 response, and the fast vanishing of the dominance of the IL-2 response. These results suggest that P. falciparum specific immune responses are first oriented towards a Th2-type of response, and later switch to Th1-type of response.

Reference scattering curves for polarization and intensity produced by aggregates and agglomerates of ethylene and kerosene soot are obtained for scattering angles in the 10-170 degrees range. The polarization measurements were obtained with the Propriétés Optiques des Grains Astronomiques et Atmosphériques instrument for particles that levitate in microgravity during parabolic flights and on the ground by an air draught technique. The intensity measurements were obtained also on the ground with a Laboratoire de Metéorologie Physique nephelometer. The maximum polarization is of the order of 80% at a scattering angle of 80 degrees at lambda = 632.8 nm and approximately 75% at an angle of 90 degrees at lambda = 543.5 nm. The polarization increases by approximately 10% when the size of the agglomerate increases from 10 microm to a few hundred micrometers. The intensity curve exhibits a strong increase at small scattering angles. These reference curves will be used in the near future for the detection of stratospheric soot by remote-sensing measurement techniques.

Anemia during childhood remains a major public health challenge in sub-Saharan Africa. To determine the prevalence of and the main risk factors for anemia in young children, we conducted a longitudinal survey in Ebolowa in southern Cameroon. Children were enrolled in two cohorts and followed during a three-year period: the first cohort was composed of 122 children from 0 to 36 months of age and the second cohort was composed of 84 children from 24 to 60 months of age. The two cohorts were followed weekly for symptomatic malaria, monthly for both symptomatic and asymptomatic malaria, and every six months for hematologic data; the children were grouped into six-month age groups. The prevalence of anemia (hemoglobin [Hb] level < 11 g/dl) was the highest in the six-month-old age group (47%) and the age-related evolution clearly showed a decrease in the prevalence from three years of age. Thus, 42% of the children less than three years of age were anemic, while 21% of the children between three and five years of age were anemic. The lowest mean +/- SD Hb content (10.7 +/- 2.1 g/dl) was observed in the six-month-old children and a regular improvement in the Hb level occurred from six months to three years of age. A stabilization was observed at a level of approximately 12 g/dl. At any age, there was no difference in mean Hb levels between children with AS and AA Hb genotypes. Hookworm infection was diagnosed in two children in the study population. Results of a multivariate analysis showed that placental malaria infection was the strongest risk factor for anemia in the six-month-old children (odds ratio [OR] = 3.6; 95% confidence interval [CI] = 1.1-12.3) and was independent of the frequency of parasitemia, parasitemia at the time of Hb measurement, or microcytosis. In the one-year-old age group, microcytosis was a significant factor related to anemia (OR = 2.8, 95% CI = 1-7.8) pointing out the role of iron deficiency at this age. Parasitemia at the time of Hb measurement was significantly associated with anemia in all age groups (except in 54- and 60-month-old groups). Strategies to decrease the prevalence of anemia in young children in southern Cameroon should include chemoprophylaxis for pregnant women, prevention of acquired malaria infection in both pregnancy and infancy, and prevention of nutritional iron deficiency.

In areas endemic for malaria, pregnant women frequently present with a placenta that has been parasitized by Plasmodium falciparum, an infection associated with a reduction in the birth weight of the offspring. However, the impact of placental infection on malaria-related morbidity during the infant's first years of life has not been investigated. Between 1993 and 1995, 197 children in southern Cameroon were followed weekly clinically and monthly parasitologically. The dates of first positive blood smear and the evolution of the parasite prevalence rates were compared between infants born to mothers presenting with (n = 42) and without (n = 155) P. falciparum infection of the placenta. Infants born to placenta-infected mothers were more likely to develop a malaria infection between 4 and 6 months of age; then the difference progressively disappeared. Similarly, parasite prevalence rates were higher in placenta-infected infants from 5 to 8 months of age. Thus, malarial infection of the placenta seems to result in a higher susceptibility of infants to the parasite. This was not related to maternally transmitted antibodies, as specific antibody levels were similar in both groups of infants. A better understanding of the involved mechanisms may have important implications for the development of malaria control strategies.

Six commercial agglutination tests designed for the identification of Staphylococcus aureus were compared by using a strain collection which included 512 staphylococci representing 33 species (318 isolates of Staphylococcus aureus [including 144 oxacillin resistant], 46 S. epidermidis isolates, 15 S. haemolyticus isolates, 12 S. saprophyticus isolates, 29 S. schleiferi isolates, 30 S. lugdunensis isolates, and 62 other coagulase-negative staphylococci). This group also included a proportion of strains with unusual phenotypes (e.g., 19 coagulase-negative S. aureus isolates, 26 clumping factor-negative S. aureus isolates, and 4 S. aureus isolates each with a double deficiency). The overall sensitivity for identification of typical and atypical S. aureus was high with the Staphaurex Plus test (Murex Biotech) (99.7%), the Pastorex Staph Plus test (Sanofi Diagnostics Pasteur) (99.7%), and the Slidex Staph Plus test (bioMérieux) (100%). The overall rate of specificity was affected by the unusual inclusion in this study of a high proportion of non-S. aureus species, such as S. lugdunensis and S. schleiferi, which express a clumping factor and therefore produce a positive result with the agglutination tests.

The cytochemical demonstration of acetylcholinesterase is theoretically and experimentally evaluated with a model system. The model is an artificial proteic membrane in which acetylcholinesterase homogeneously is immobilized chemically by a bifunctional agent, glutaraldehyde. The copper-thiocholine histochemical method is studied kinetically and the system is simulated by computer calculations based on experimental kinetic parameters and numerical analysis methods. In addition, the corresponding electron micrographs are presented. These studies lead to the conclusions that the system is ruled by diffusional constraints and that enzyme distribution and repartition of the insoluble electron dense product are not circumscribed by any specific conditions.

The presynaptic action of glutamate was investigated in crayfish neuromuscular preparations. The excitability of locally stimulated nerve terminals increased during the perfusion of glutamate. Electrotonically propagated depolarizations were recorded in the excitatory axons when glutamate was ionophoretically applied to sensitive spots on the muscle membrane. Depolarizations of the axon were also obtained when glutamate, GABA and aspartate were added to the bath. In order to evaluate the part of the presynaptic effect in the depolarization induced in muscle fibres, nerve terminals were damaged either by treatment with high-Ca solutions or by denervation. In both cases, a decreased sensitivity to glutamate was found. Possible relationships between the nerve terminal damage and the change in the response to glutamate are proposed.

A histochemical model dealing with an immobilized bienzyme system (glucose oxidase-peroxidase) is presented. The model is an artificial proteic membrane obtained by a previously described co-cross-linking process. The kinetic properties of free and immobilized horseradish peroxidase were studied when 3,3'-diaminobenzidine is used as a hydrogen donor substrate. A new direct method was developed for immobilized enzyme activity measurements. Computer simulation based on experimental kinetic parameters was performed in order to discuss electron microscopy results. By changing diffusion limitations, various profiles of insoluble product were visualized inside the proteic film and no geometrical similarity was seen between enzyme distributions and insoluble osmiophilic product patterns.

With the periodic acid-thiosemicarbazide-silver proteinate procedure for the detection of polysaccharides in thin sections, glycogen is localized in the cavities of centrioles and basal bodies, within the axoneme (and surrounding it), in mitochondria, and in the "packing" cytoplasm of the middle piece of spermatozoa of several invertebrate and vertebrate species. The cytochemical localization of glycogen is verified by extraction with alpha-amylase solution. These findings establish the existence of stored glycogen in sperm. The polysaccharide presumably serves as an endogenous source of energy in the absence of extracellular metabolites, under either aerobic or anaerobic conditions. Other hypotheses on the physiological significance of intracellular glycogen stores in sperm are discussed. Sperm that store glycogen contain some enzymes of glycogen metabolism. In the presence of glucose-1-phosphate, ATP, and Mg(++) ions, an amylophosphorylase catalyzes the in vivo synthesis of glycogen. The newly formed product resembles gamma-particles, and is digestible with alpha-amylase.

The mitochondrial derivative of the sperm cell of the Gastropod Helix is endowed with a compartment loaded with glycogen (Personne et André, 1964). The aim of this work is to establish whether this mitochondrial glycogen is synthesized in the mitochondrial derivative itself or elsewhere in the cell. For this purpose, living sperm were first incubated in a medium containing glucose 1-phosphate, then fixed, sectioned, and stained specifically for polysaccharides by the phosphotungstic acid technique or the periodic acid-thiosemicarbazide-silver proteinate technique. Comparison with controls shows that a synthesis of glycogen occurred during the time of incubation. It can be inferred from this result that an amylophosphorylase system controlling the metabolism of polysaccharides is present in the mitochondrial derivative itself. Results obtained with the iodine technique indicate that the original glycogen molecules are elongated during the experiment. It seems probable that the amylophosphorylase system demonstrated here accounts for at least a part of the proteinaceous coat morphologically detectable around each individual glycogen particle.