Drugs and immunity: cannabinoids and their role in decreased resistance to infectious disease

Marijuana, Cannabis sativa, elicits a variety of effects in experimental animals and humans. Delta-9-tetrahydrocannabinol (THC) is the major psychoactive component in marijuana. This substance has been shown, also, to be immunosuppressive and to decrease host resistance to bacterial, protozoan, and viral infections. Macrophages, T lymphocytes, and natural killer cells appear to be major targets of the immunosuppressive effects of THC. Definitive data which directly link marijuana use to increased susceptibility to infection in humans currently is unavailable. However, cumulative reports indicating that THC alters resistance to infection in vitro and in a variety of experimental animals support the hypothesis that a similar effect occurs in humans.     

Critical analysis of long-term tests for carcinogenicity

The objective of long-term carcinogenicity studies is to observe test animals for a major portion of their lifespan for the development of neoplastic lesions during or after exposure to various doses of a test substance given by an appropriate route. Studies of this type require careful planning and documentation of the experimental design, a high standard of pathology, good animal care and suitable statistical analysis. These requirements are well known and have not undergone major changes during recent years. Rather than giving details of these requirements, which can now be found in many publications, this paper attempts to indicate some of the problems involved in a long-term carcinogenicity study.     

Restrictive myocardiopathy in children

Four children, three males and one female, aged 1.5 months to 11 years, with restrictive cardiomyopathy are described. One had patent ductus arteriosus in association. Hepatomegaly, abnormal second heart sound and signs of pulmonary venous congestion in chest X-ray were the most consistent clinical findings. Diagnosis was based on echocardiographic findings, cardiac catheterization data and results of pathology. The most frequent echocardiographic sign was the enlargement of both atria but with the ventricles within normal size and normal systolic function. Abnormalities in second phase of the ventricular filling were recorded in 2D-echo Doppler and cardiac catheterization, where a dip and plateau morphology of ventricular tracings was recorded. Metabolic studies performed in two children were normal, and any child had hypereosinophilia. Two children died, one was lost for follow-up and another is asymptomatic. Remarks on medical and surgical management are made.     

Magnetization and Curie Temperature of Ilmenite–Hematite Ceramics

The morphology, structure, and magnetic properties of the magnetic semiconductor ceramic Ilmenite–Hematite (IH), (1− x )FeTiO₃– x Fe₂O₃, were studied as a function of the composition x . The magnetic ordering temperatures that we observed were consistently higher than those reported previously and were, for most of the composition range, above room temperature. We rule out the formation of Fe clusters as the origin of the magnetic properties. These magnetic properties of IH ceramics, in combination with their semiconducting characteristics, render them promising for spin-electronic applications.     

Transzygotic carcinogenic effect of nitrosoethylurea in rats

The results of two experiments on the transzygotic transfer of the nitrosoethylurea (NEU) carcinogenic effect are presented. In the first experiment female rats received 60 mg/kg b. w. of NEU at 16, 18 and 20th day of the pregnancy. Their F1 descendants developed multiple tumours of the nervous system after a short latency (up to 40 weeks). The rats of F2, F3, F4 and F5 generations which were not in a direct contact with NEU developed a statistically higher incidence of tumours occurring spontaneously (those of mammary gland, pituitary, and haematopoietic tissue). However, the incidence of nervous system tumours was at the level of controls. In the second experiment male rats received 80 mg/kg b. w. of NEU and then were mated with untreated females. The incidence of the nervous system tumours in the descendants of treated males was somewhat higher than in the controls. The manifestations and mechanisms of the transzygotic effect are discussed.     

The quality of run-off from an irrigated market garden area in Brazil

This paper presents the results of a study carried out in Brazil to determine the effects of irrigation and fertiliser use on the quality characteristics of run-off from an agricultural area used for intensive cultivation of market garden produce.The results show that during dry weather the discharge of nutrients from the cultivated area when irrigation is taking place is equivalent to 7 kg ha⁻¹ yr⁻¹ N and 1 kg ha⁻¹ yr⁻¹ P. Considerable accumulation of nutrients took place in the soil during the growing season, over the 129-day survey period the nutrient content of the top soil increased by approximately 590 g m⁻²N and P and 780 g m⁻²K. This accumulation was derived from fertilisers which were applied at rates of 1136 kg ha⁻¹N, 978 P and 1367 K. During wet weather the nutrients which had accumulated in the soil were washed out.     

Structure, orientation, and conformational changes in transmembrane domains of multidrug transporters

Multidrug transporter proteins promote the active transmembrane efflux of noxious drugs, thereby decreasing their accumulation in the intracellular medium and reducing their therapeutic efficiency. Expression of such proteins drastically reduces the efficiency of chemotherapeutic treatments against cancer and various infectious diseases. To overcome major difficulties related to the crystallization of membrane proteins, other experimental approaches have been developed to gain information on the structural changes involved in drug transport. We examine here and illustrate with a few examples how infrared and fluorescence spectroscopy can provide new insights into the structure of the membrane domains of multidrug transporters in particular. Such domains contain the drug-binding site(s) and mediate the passage of substrates across the cell membrane.     

Measurements and thermodynamic modeling of the solubility of squalene in supercritical carbon dioxide

The solubility of squalene in supercritical carbon dioxide (SC-CO₂) was measured and it was analyzed together with the values obtained by Catchpole and von Kamp (1997). The results showed that the experimental values obtained in this work agreed with the order of magnitude of those reported in the literature and correlated well with the Chrastil equation. The thermodynamic modeling using the Peng–Robinson equation of state only correlated well with the experimental values obtained when the critical properties and acentric factor reported by Ruivo et al. (2004) were used. The values predicted for the solubility of squalene in SC-CO₂ using modeling employing the GC-EOS, were only of the same order of magnitude as the experimental values for pressures below 200 bar, and its performance was influenced by the value of the critical hard sphere diameter.     

Synthesis of BaTiO3 by soft chemistry routes

In this paper we report a comparison concerning the properties of BaTiO₃ (BTO) ceramics obtained by two soft chemical routes, modified Pechini method and thermal decomposition of oxalate-based precursor. XRD data show the formation of single phase BaTiO₃ with tetragonal symmetry when the polymeric citrate-based precursor was annealed at 850 °C, 2 h. In the case of oxalate based-precursor, longer thermal treatment is required to obtain BaTiO₃ free of any secondary phases. For BaTiO₃ powders prepared by modified Pechini method, TEM and SEM investigations revealed the obtaining of uniformly sized particles forming spherical agglomerates inside large, non-uniform and partially sintered aggregates. The powders synthesized via oxalate route show particles of various sizes, with the same tendency of spherical agglomerates formation, but unlike the modified Pechini synthesis, more uniform and smaller aggregates with well-defined hexagonal-like shape were noticed. The relative permittivity values of 6,478 and 5,088 at Curie temperatures of 127 and 130 °C and low dielectric losses (tan δ?=?0.012) at room temperature were obtained for ceramic samples synthesized via Pechini method and oxalate route, respectively.     

A double-layered carbon nanotube array with super-hydrophobicity

The growth of double-layered vertical-aligned carbon nanotube (CNT) arrays by a single step chemical vapor deposition is reported. The deactivation and reactivation of catalyst particles may be the cause of such a growth process. An interesting morphology difference between the top and the bottom CNT layers was observed. In contrast to the smooth surface of the top CNT layer, the surface of the bottom layer shows hierarchical structures. The surface structures of the bottom CNT layer allow this surface to exhibit super-hydrophobic properties and excellent self-cleaning abilities.