Synthesis and antimalarial activity of 2-methoxyprop-2-yl peroxides derivatives

2-Methoxyprop-2-yl peroxides were synthesized and evaluated in vitro against Plasmodium falciparum. These acyclic artemisinin-related peroxides revealed moderate to good activity but were devoid of alkylating property towards the synthetic model of heme Mn(II)-TPP.     

Prevention of diseases caused by Staphylococcus aureus using the peptide RIP

Staphylococcus aureus causes many diseases including cellulitis, keratitis, osteomyelitis, septic arthritis and mastitis. The heptapeptide RIP has been shown to prevent cellulitis in mice, which was induced by S. aureus strain Smith diffuse. Here we show that RIP can also significantly reduce the overall pathology and delay the onset of disease symptoms in several other models of S. aureus infections, including: keratitis (tested in rabbits against S. aureus 8325-4), osteomyelitis (tested in rabbits against S. aureus MS), mastitis (tested in cows against S. aureus Newbould 305, AE-1, and environmental infections) and septic arthritis (tested in mice against S. aureus LS-1). These findings substantiate that RIP is not strain specific in its inhibitory activity and that RIP is an effective inhibitor of bacterial pathology at multiple body sites following diverse routes and doses of administration. These findings strongly evidence the potential value of RIP as a chemotherapeutic agent.     

Effect of Chronic Variate Stress on Thiobarbituric-Acid Reactive Species and on Total Radical-Trapping Potential in Distinct Regions of Rat Brain

It has been suggested that oxidative stress is involved in aging and neuropathologic disorders. In addition, chronic stress and high corticosterone levels are suggested to induce neuronal death. The aim of this study is to verify the effect of chronic variate stress on lipoperoxidation and on the total radical-trapping potential (TRAP) in hippocampus, hypothalamus and cerebral cortex. Adult male Wistar rats were submitted to different stressors during 40 days. Lipid peroxide levels were assessed by the thiobarbituric acid reactive species (TBARS) reaction, and TRAP was measured by the decrease in luminescence using the 2-2-azo-bis(2-amidinopropane)-luminol system. The results showed that in cerebral cortex homogenates chronic stress induces an increase in oxidative stress. In hypothalamus a decreased lipoperoxidation was observed, however TRAP showed no difference. In hippocampus no difference was observed. We concluded that prolonged stress induces oxidative stress which varies selectively with the brain region.     

Inhibitors of the carrier-mediated influx of auxin in suspension-cultured tobacco cells

 Active auxin transport in plant cells is catalyzed by two carriers working in opposite directions at the plasma membrane, the influx and efflux carriers. A role for the efflux carrier in polar auxin transport (PAT) in plants has been shown from studies using phytotropins. Phytotropins have been invaluable in demonstrating that PAT is essential to ensure polarized and coordinated growth and to provide plants with the capacity to respond to environmental stimuli. However, the function of the influx carrier at the whole-plant level is unknown. Our work aims to identify new auxin-transport inhibitors which could be employed to investigate its function. Thirty-five aryl and aryloxyalkylcarboxylic acids were assayed for their ability to perturb the accumulation of 2,4-dichlorophenoxyacetic acid (2,4-D) and naphthalene-1-acetic acid (1-NAA) in suspension-cultured tobacco (Nicotiana tabacum L.) cells. As 2,4-D and 1-NAA are preferentially transported by the influx and efflux carriers, respectively, accumulation experiments utilizing synthetic auxins provide independant information on the activities of both carriers. The majority (60%) of compounds half-inhibited the carrier-mediated influx of [¹⁴C]2,4-D at concentrations of less than 10 μM. Most failed to interfere with [³H]NAA efflux, at least in the short term. Even though they increasingly perturbed auxin efflux when given a prolonged treatment, several compounds were much better at discriminating between influx and efflux carrier activities than naphthalene-2-acetic acid which is commonly employed to investigate influx-carrier properties. Structure-activity relationships and factors influencing ligand specificity with regard to auxin carriers are discussed. Received: 28 June 1999 / Accepted: 28 August 1999     

Monitoring the domiciliary and peridomiciliary invasion process of Triatoma rubrovaria in the State of Rio Grande do Sul, Brazil

The presence of Triatoma rubrovaria in Brazil has only been confirmed in the States of Paraná and Rio Grande do Sul (RS), where it is found naturally infected with Trypanosoma cruzi. In the wild environment it occurs in rocky habitats and has an eclectic diet, feeding from cockroaches, reptiles and mammals. Data from the Chagas Disease Control Program obtained by the Funda??o Nacional de Saúde, between 1975 and 1997, indicate a growing domiciliary and peridomiciliary invasion of T. rubrovaria in RS, where it has become the most frequently Triatominae species captured in this state since the control of Triatoma infestans. In order to monitor this process, we analyzed collection data derived from 22 years of control campaigns against T. infestans. Collection data for triatomines from domestic habitats show an inverse relationship, with high numbers of T. infestans and low numbers of T. rubrovaria during 1976-1987, compared to the following ten years, 1986-1997, when the number of T. infestans dropped drastically and that of T. rubrovaria increased. There are no consistent indications of intradomiciliary colonization by T. rubrovaria, since only low numbers of nymphs have been captured in the intradomiciliary ecotopes. Nevertheless, this species appears to have preadaptive characteristics for anthropic ecotopes, and should be kept under constant epidemiological surveillance.     

Ultrastructure of muscle cells from a few selected turbellarians: possible correlations between form and function

A comparative ultrastructural study of muscle cells from several turbellarian species revealed a basic smooth type of construction, with thick and thin myofilaments. However, the distribution of contractile elements, "dense bodies", smooth reticulum, mitochondria, as well as junctional specializations was found to vary within different systems. This variability is probably related to greater or lesser physical demands on the musculature. From a mechanical viewpoint, the most ‘powerful’ muscular system studied was represented by the pharyngeal bulb of Geocentrophora applanata, in which muscle fibers were organized into a compact, square reticulum, hemidesmosomes occurred in large numbers, and myofilaments were grouped in patches reminiscent of A and I bands of striated muscles. At the other extreme, muscular fibrils of the catenulids studied were thin and regularly spaced along the body wall, and the branched ends of radial myofibrils in the parenchyma were connected to the epithelial layer. This revised version was published online in July 2006 with corrections to the Cover Date.     

The loss of immunity in directly transmitted infections modeling: Effects on the epidemiological parameters

When directly transmitted infectious diseases are modeled assuming an everlasting induced immunity (and constant contact rate), there are well-established formulas to deal with, which is not true if we include the loss of induced immunity. In general, the immunity induced by the disease is everlasting. We propose a model considering the loss of immunity and present methods for the estimation of two epidemiological parameters: the force of infection and the basic reproduction ratio. We also analyze the effects of the loss of immunity on these parameters. Based on these results, we conclude that reinfection can play an important role in highly vaccinated populations.     

Effect of the oxygen supply on pattern of growth and corrinoid and organic acid production of Propionibacterium shermanii

Propionibacterium shermanii CDB 10014 is able to grow even at high oxygen transfer rates (24.0 mmol O₂ l⁻¹ h⁻¹), in contrast to reports in the specialised literature, where all Propionibacteria are considered oxygen-sensitive microorganisms. Propionic acid is the main product in anaerobiosis. The presence of oxygen in the system leads to an inhibition of propionic acid production while acetic acid formation is enhanced. At high oxygen supply rates no propionic acid is produced and acetic acid is the main product. Lactic acid is also produced in reasonable quantities (2.7 g l⁻¹). The growth rate (μ_max) is higher in anaerobiosis (0.19 h⁻¹) than in aerobiosis (0.12–0.15 h⁻¹). The cell yield is higher in aerobiosis (0.18–0.22 g g⁻¹) than in anaerobiosis (0.14 g g⁻¹) suggesting the oxidative metabolism of glucose by Propionibacterium shermanii CDB 10014. No corrinoid production was detected at oxygen transfer rates of more than 13.6 mmol l⁻¹ h⁻¹. Received: 10 September 1997 / Received revision: 6 January 1998 / Accepted: 9 January 1998     

Floral anatomy of Neotropical species of Mayacaceae

The Mayacaceae are a monogeneric monocot family of herbs that grow on swampy areas in the Americas and in Africa. Both the number of species constituting the family and its inter-familial relationships are unclear. By describing and comparing the floral anatomy of Mayaca fluviatilis, M. fluviatilis f. kunthii, M. longipes and M. sellowiana we have identified some features that delimit the species. These include: arrangement of flowers on the stem, shape of stamens, size of apical pores, disposition of microsporangia, number of ovules and shape of the stylar canal. We concluded that M. fluviatilis f. kunthii should be considered as a species (M. kunthii) rather than a forma. Other characters such as number of stamens and microsporangia, placentation, ovule type and cell numbers in the pollen grain support the placement of the Mayacaceae within Poales.     

Physicochemical and mechanical characterization of galactomannan from Mimosa scabrella: Effect of drying method

The galactomannan from Mimosa scabrella Bentham was extracted on a pilot plant scale and dried either by vacuum oven (GVO) or by spray-drier (GSD) to evaluate the effect of the drying technique on the powder quality and its applicability as excipient in solid dosage forms. The analysis by high performance size exclusion chromatography (HPSEC) coupled to multiangle laser light scattering (MALLS) suggests that both products behave as semi-flexible polymers, although the GSD showed more aggregation at molecular level (～10%) and higher chain stiffness (Lp 9.1 nm). TG and DSC analysis showed weight loss event with peak at 299.7 and 311.9 °C to GVO and GSD, respectively, as well and higher ash content for GSD sample, in both inert and oxidant atmosphere. The X-ray diffraction confirmed the amorphous nature of both galactomannans although GVO showed high crystallinity. The GSD showed lower density (1.009 g/cm³), higher cohesiveness (repose angle 35.5°, compressibility 32.2% and absence of flow), smaller and more spherical particles than GVO sample, both with high polydispersion. As vacuum oven-drying resulted in a like fibrous material, spray-drying appears as an alternative method easy to extrapolate in industry, requiring a glidant incorporation to improve the powder flowability.