Pathology of Toxoplasma gondii infection in the nude rat. An experimental model of toxoplasmosis in the immunocompromised host?

Genetically athymic nu/nu (nude) rats, deficient in T cells, die from infection with various Toxoplasma gondii strains, including RH and Prugniaud strains. In contrast, these strains cause chronic infections without apparent symptoms in immunocompetent non-nude rats. We show here that nude rats die in two to three weeks after RH infection and three to four weeks after Prugniaud infection. Histological examination of brains from nude rats at different time points after infection, revealed an absence of lesions after RH strain infection and cysts with usually no inflammation after Prugniaud infection. Lungs from nude rats developed a fibrin alveolitis using either strain, whereas myocarditis with focal areas of necrosis were observed only after Prugniaud infection. Cysts and, in some cases, tachyzoites in the necrotic lesions were easily identifiable. The two strains of T. gondii elicited in nude rats a granulomatous hepatitis that only differed in intensity. Spleen and mesenteric lymph nodes appeared totally non reactive in both cases. This model allows immunological and parasitological studies by comparison with immunocompetent rat infection. Published data concerning toxoplasma pathology in AIDS, therefore, suggest that acute toxoplasma infection in nude rats may be a useful model for studying disseminated forms of toxoplasma infection found in AIDS patients.     

Experimental fetal tracheal ligation reverses the structural and physiological effects of pulmonary hypoplasia in congenital diaphragmatic hernia

Infants with congenital diaphragmatic hernia (DH) and profound pulmonary hypoplasia are currently unsalvageable. The authors previously demonstrated that tracheal ligation (TL) accelerates fetal lung growth and reverses the pulmonary hypoplasia of fetal nephrectomy. The purpose of this study was to determine if the pulmonary hypoplasia of experimental DH could be similarly reversed and, if so, whether the resulting lungs would show better function than those of their DH counterparts. Eighteen fetal lambs were divided into three experimental groups of six animals each. In group 1, DH was created at 90 days' gestation. In group 2, DH was created at 90 days' gestation and TL performed during the same operation. Group 3 consisted of sham-operated controls. These animals were delivered near full-term, and their lungs analyzed by standard morphometric techniques. Ten additional fetal lambs were divided into two experimental groups of five animals each. In group 4, DH was created at 90 days' gestation. In group 5, DH was created at 90 days' gestation and TL performed 20 days later, at 110 days' gestation. These animals were pressure-ventilated via tracheostomy over a 2-hour period in which PaO2, PaCO2, and compliance were measured. Intratracheal pressure (ITP) was measured at the time of delivery in all groups. Upon retrieval, DH animals had abdominal viscera in the chest and small lungs; in contrast, DH/TL animals had the herniated viscera reduced from the chest by enlarged lungs. DH/TL lungs showed markedly increased growth, with significant increases in lung volume:body weight ratio (LV:BW; P = .0001), alveolar surface area (ALV.SA; P = .0001), and alveolar number (ALV#) (P = .0001) when compared with those of the DH or control group. This growth was associated with a normal maturation pattern based on histological appearance, normal airspace fraction, and normal alveolar numerical density. ITP in the DH/TL group was increased when compared with that of DH and control animals (P = .0001). Total lung DNA and protein were both elevated in the DH/TL animals (P = .0001). However, the DNA:protein ratio remained normal, suggesting lung growth had occurred through cell proliferation, not by hypertrophy. When ventilated over a range of settings, DH/TL lungs were more compliant (P = .0001) and achieved higher PaO2s (P < .003) and lower PaCO2s (P = .0001) than their DH counterparts. From these data, the authors conclude: (1) Experimental fetal DH produces hypoplastic lungs that are not capable of adequate gas exchange with conventional ventilation.(ABSTRACT TRUNCATED AT 400 WORDS)     

Improved column-switching liquid chromatographic method for the determination of the enantiomers of mefloquine

A liquid chromatographic method for the determination of the enantiomers of mefloquine has been improved. The chromatography involved two columns: an achiral cyanopropyl stationary phase for the quantification of (+/-)-mefloquine and a chiral naphthyl-urea stationary phase for the determination of the enantiomeric ratio. Compared with the previous method, which needed two detectors, this one used one detector-integrator to which the two columns are connected alternately by an automated column-switching system. The method is suitable for the quantification (0.05 microgram/ml) of mefloquine and the determination of enantiomeric ratios from 500-microliters plasma samples with ultraviolet detection.     

Lipopolysaccharide primes human alveolar macrophages for enhanced release of superoxide anion and leukotriene B4: self-limitations of the priming response with protein synthesis

Human alveolar macrophages (AM) can produce potent reactive oxygen intermediates (ROI) and arachidonic acid metabolites (eicosanoids), which have important roles in host defense and the pathogenesis of some diseases of the lung. Bacterial lipopolysaccharide (LPS) is believed to cause profound lung injury and can prime mouse peritoneal macrophages for the enhanced secretion of ROI and eicosanoids. Therefore, we investigated the effect of LPS pretreatment on the ability of AM to release superoxide anions (O2-) and leukotriene B4 (LTB4). LPS can prime AM for the enhanced secretion of O2- and LTB4, regardless of whether they are derived from nonsmokers or smokers. Moreover, judging from the time-response characteristics, this priming for LTB4 release could be inhibited in the later stages of pretreatment, when the O2(-)-releasing capacity was enhanced. The priming inhibition was prevented, at least in part, by cycloheximide, but not by SOD and/or catalase. In addition, cycloheximide also inhibited the priming for O2- release. Hence, protein synthesis might be necessary for the priming for O2- release and for inhibiting the priming for LTB4 release. This phenomenon of self-limiting the priming response with LPS seems to be very important when we consider the high oxygen tension in the lungs and the many bacterial substances inspired into alveoli.     

THE INFLUENCE OF LOAD MISALIGNMENT DURING UNIAXIAL LOW-CYCLE FATIGUE TESTING—I: MODELLING

Abstract— A quantitative model has been proposed which predicts the extent of lifetime scatter in low-cycle fatigue due to the influence of bending caused by load misalignment. The main components of the model are the mechanism of bending, the type of extensometer used to control strain and the fatigue characteristics of the material being assessed. Three mechanisms of bending have been studied and it is argued that the most damaging one is a consequence of a lateral offset in the centre-lines of the load-train with respect to either a machine's frame or ram. Scatter in lifetime is a maximum when strain is controlled by a single extensometer (which is generally the case) and when fatigue behaviour is dictated by crack initiation at the largest surface defect. Two types of scatter have been examined, (i) repeatability scatter due to testing practice within a single laboratory, and (ii) reproducibility scatter between laboratories. An example of the magnitude of reproducibility scatter due to bending has been given by using an equation based on the universal slopes method due to Manson.     

Drug therapy of hemiballism. Review of the literature and personal observations

Hemiballism is a rare hyperkinetic disorder which is characterized by irregular vigorous rotatory movements of the limbs of one side of the body. The disabling and exhausting movements with their high risk of severe injuries require an acute drug treatment. However, there are no common guidelines for the treatment of this disorder. Therefore we reviewed the available literature to establish a concept for a rational symptomatic drug treatment. Furthermore, own observations in 6 patients with hemiballism of different origins are reported.     

Dynamic lithium-ion battery model for system simulation

Presents here a complete dynamic model of a lithium ion battery that is suitable for virtual-prototyping of portable battery-powered systems. The model accounts for nonlinear equilibrium potentials, rate- and temperature-dependencies, thermal effects and response to transient power demand. The model is based on publicly available data such as the manufacturers' data sheets. The Sony US18650 is used as an example. The model output agrees both with manufacturer's data and with experimental results. The model can be easily modified to fit data from different batteries and can be extended for wide dynamic ranges of different temperatures and current rates.     

Solar/UV-induced photocatalytic degradation of three commercial textile dyes.

The photocatalytic degradation of three commercial textile dyes with different structure has been investigated using TiO(2) (Degussa P25) photocatalyst in aqueous solution under solar irradiation. Experiments were conducted to optimise various parameters viz. amount of catalyst, concentration of dye, pH and solar light intensity. Degradation of all the dyes were examined by using chemical oxygen demand (COD) method. The degradation efficiency of the three dyes is as follows: Reactive Yellow 17(RY17) > Reactive Red 2(RR2) > Reactive Blue 4 (RB4), respectively. The experimental results indicate that TiO(2) (Degussa P25) is the best catalyst in comparison with other commercial photocatalysts such as, TiO(2) (Merck), ZnO, ZrO(2), WO(3) and CdS. Though the UV irradiation can efficiently degrade the dyes, naturally abundant solar irradiation is also very effective in the mineralisation of dyes. The comparison between thin-film coating and aqueous slurry method reveals that slurry method is more efficient than coating but the problems of leaching and the requirement of separation can be avoided by using coating technique. These observations indicate that all the three dyes could be degraded completely at different time intervals. Hence, it may be a viable technique for the safe disposal of textile wastewater into the water streams.