Hereditary spastic paraplegia: report of two siblings

A Japanese boy had marked generalized hypotonia and weakness and progressive respiratory failure since birth. Left biceps brachii muscle biopsy at 47 days of age showed marked variation in muscle fiber size, and nemaline and/or cytoplasmic bodies in approximately 10% of the muscle fibers. To our knowledge, the presence of nemaline and cytoplasmic bodies in the same muscle has not been previously reported. The severity of his respiratory failure and muscle weakness were thought to be related to muscle immaturity since there were many undifferentiated type 2C fibers.     

CD34-deficient mice have reduced eosinophil accumulation after allergen exposure and show a novel crossreactive 90-kD protein

CD34 is expressed on the surface of hematopoietic stem/progenitor cells, stromal cells, and on the surface of high-endothelial venules (HEV). CD34 binds L-selectin, an adhesion molecule important for leukocyte rolling on venules and lymphocyte homing to peripheral lymph nodes (PLN). We generated CD34-deficient mutant animals through the use of homologous recombination. Wild-type and mutant animals showed no differences in lymphocyte binding to PLN HEV, in leukocyte rolling on venules or homing to PLN, in neutrophil extravasation into peritoneum in response to inflammatory stimulus, nor in delayed type hypersensitivity. Anti-L-selectin monoclonal antibody (MEL-14) also inhibited these immune responses similarly in both CD34-deficient and wild-type mice. However, eosinophil accumulation in the lung after inhalation of a model allergen, ovalbumin, is several-fold lower in mutant mice. We found no abnormalities in hematopoiesis in adult mice and interactions between mutant progenitor cells and a stromal cell line in vitro were normal. No differences existed in the recovery of progenitor cells after 5-fluorouracil treatment, nor in the mobilization of progenitor cells after granulocyte colony-stimulating factor treatment compared with wild-type animals. Surprisingly, although CD34 was not expressed in these mice, a portion of its 90-kD band crossreactive with MECA79 remained after Western blot. Thus, we have identified an additional molecule(s) that might be involved in leukocyte trafficking. These results indicate that CD34 plays an important role in eosinophil trafficking into the lung.     

Kinetics of aqueous oxidation of tantalum from chronopotentiometric measurements

Theoretical mechanisms and growth laws for the initial oxidation of metals are briefly reviewed. The oxidation of tantalum was studied chronopotentiometrically at temperatures between 0°C and 40°C in an oxygen-free electrolyte.

The probable rate-determining steps for the two different growth laws observed are deduced by comparison of the time dependence of the experimentally determined local oxidation current to theoretical local-current/time functions derived from assumed growth laws.

Tantalum oxidizes initially according to a direct logarithmic law, the slow step being tunnelling of electrons through the oxide film. At 40°C a transition from a direct logarithmic to a parabolic growth law is observed. The interpretation is that the diffusion of electrons which have been injected thermionically into the oxide film becomes rate-determining at film thicknesses for which current due to electron tunnelling becomes negligible.     

Predicting performance of parallel computations

An accurate and computationally efficient method for predicting the performance of a class of parallel computations running on concurrent systems is described. A parallel computation is modeled as a task system with precedence relationships expressed as a series-parallel directed acyclic graph. Resources in a concurrent system are modeled as service centers in a queuing network model. Using these two models as inputs, the method outputs predictions of expected execution time of the parallel computation and the concurrent system utilization. The method is validated against both detailed simulation and actual execution on a commercial multiprocessor. Using 100 test cases, the average error of the prediction when compared to simulation statistics is 1.7%, with a standard deviation of 1.5%; the maximum error is about 10%     

Equivalence-set genes partitioning using an evolutionary-DP approach

Computation of transitive-closure equivalence sets has recently emerged as an important step for building static and dynamic models of gene network from DNA sequences. We present an evolutionary-DP approach in which dynamic programming (DP) is embedded into a genetic algorithm (GA) for fitness function evaluation of small equivalence sets (with m genes) within a large-scale genetic network of n genes, where n/spl Gt/m. This approach reduces a computation-intensive optimal problem of high dimension into a heuristic search problem on /sub n/C/sub m/ candidates. The DP computation of transitive closure forms the basic fitness evaluation for selecting candidate chromosomes generated by GA operators. By introducing bounded mutation and conditioned crossover operators to constrain the feasible solution domain, small transitive-closure equivalence sets for large genetic networks can be found with much reduced computational effort. Empirical results have successfully demonstrated the feasibility of our GA-DP approach for offering highly efficient solutions to large scale equivalence gene-set partitioning problem. We also describe dedicated GA-DP hardware using field programmable gate arrays (FPGAs), in which significant speedup could be obtained over software implementation.     

The effect of heavy metals on nitrogen and oxygen demand removal in constructed wetlands

The objective of this study is to investigate the respective effects of Zn, Pb and Cd as well as the combined effect of Zn, Pb, Cd and Cu on the removal of nitrogen and oxygen demand in constructed wetlands. Four laboratory-scale gravel-filled subsurface-flow constructed wetland units planted with cattails (Typha latifolia) were operated outdoors and fed with primary-treated domestic wastewater at a constant flow rate of 25 ml/min. After 6 months, three of the wetland units were fed with the same type of wastewater spiked with Zn(II), Pb(II) and Cd(II), respectively, at 20, 5 and 1 mg/l for a further 9 months. The remaining unit was fed with the same type of wastewater spiked with a combination of Zn(II), Pb(II), Cd(II) and Cu(II) at concentrations of 10, 2.5, 0.5 and 5 mg/l, respectively, over the same period. The chemical oxygen demand (COD) and ammoniacal nitrogen (AN) concentrations were monitored at the inlet, outlet and three additional locations along the length of the wetland units to assess the performance of the wetland units at various metal loadings. At the end of the study, all cattail plants were harvested for the determination of total Kjeldahl nitrogen and metal concentrations. The results showed that the COD removal efficiency was practically independent of increasing metal loading or a combination of metal loadings during the duration of the study. In contrast, the AN removal efficiency deteriorated progressively with increasing metal loading. The relative effect of the heavy metals was found to increase in the order: Zn相似文献   

Spectroellipsometric studies of 0.9PbMg1/3Nb2/3O3-0.1PbTiO3 thin films

0.9PbMg_1/3Nb_2/3O₃-0.1PbTiO₃ (PMN-PT) films of different thickness, ranging from 75 to 450 nm, were prepared on La_0.5Sr_0.5MnO₃ (LSMO)-buffered LaAlO₃ (LAO) substrates by pulsed laser deposition (PLD). The structural properties of these films were characterized by X-ray diffraction. The –2 scans indicated that all the films have a pure perovskite phase containing no impurity. The - and -scans confirmed that all the films possess a heteroepitaxial relation of PMN-PT(1 0 0) LSMO(1 0 0) LAO(1 0 0) structure. The surface morphology and cross section of the films were examined by scanning electron microscopy (SEM). Their dielectric constants and the leakage currents were measured by an impedance analyzer and a leakage digital electrometer, respectively. Furthermore, spectroellipsometry (SE) was used to characterize the depth profile, refractive index, and microstructural inhomogeneities, including voids, microroughness of surface, and the electrode/film interface of these films. Based on these studies, the correlation between the electrode/film interface and the electrical properties of the films was discussed. Our results show that the ratio of the electrode/film interface thickness to the film thickness increases as the film thickness decreases. The increase in this ratio results in deterioration of the leakage current and dielectric constant of the films.     

Sac-like pouches in Blastocystis from the house lizard Cosymbotus platyurus

We report a 65-year-old male with progressive supranuclear palsy (PSP) who developed bilateral vocal cord abductor paralysis (VCAP). The patient was admitted to our hospital because of impaired gait. He was well until two years earlier, when he began to walk unsteadily. During the next two years, dysarthria and dysphagia developed and his gait worsened gradually. On admission, neurological examination showed impaired vertical and incomplete lateral gaze. His speech was slow and monotonous. Contractures were found in the neck muscles and elbows. The deep tendon reflexes were increased in the upper and decreased in the lower extremities. Babinski sign was negative. Snout and forced grasping reflexes were elicited. He showed marked bradykinesia. Magnetic resonance imaging revealed a midbrain tectum atrophy. Single photon emission tomography showed severe hypoper-fusion in the frontal cortex. No improvement was provided by the administration of levodopa-carbidopa, bromocriptine, droxydopa and amitriptyline. One month after admission, inspiratory stridor developed at night. The laryngofiberscopic examination demonstrated VCAP. An emergency tracheostomy relieved his respiratory distress. Although VCAP rarely occurs in neurodegenerative disorders other than multiple system atrophy, attention to VCAP should be required in PSP patients.     

Subunit stoichiometry of the epithelial sodium channel

The epithelial Na+ Channel (ENaC) mediates Na+ reabsorption in a variety of epithelial tissues. ENaC is composed of three homologous subunits, termed alpha, beta, and gamma. All three subunits participate in channel formation as the absence of any one subunit results in a significant reduction or complete abrogation of Na+ current expression in Xenopus oocytes. To determine the subunit stoichiometry, a biophysical assay was employed utilizing mutant subunits that display significant differences in sensitivity to channel blockers from the wild type channel. Our results indicate that ENaC is a tetrameric channel with an alpha2 beta gamma stoichiometry, similar to that reported for other cation selective channels, such as Kv, Kir, as well as voltage-gated Na+ and Ca2+ channels that have 4-fold internal symmetry.     

In vitro susceptibility studies of Malaysian Plasmodium falciparum isolates and clones against schizontocidal drugs

Spasmodic dysphonia (SD) is at present defined as focal dystonia. Botulinum toxin (BT) injection is the treatment of choice for SD. BT is usually injected by a percutaneous route, but a direct, visually guided transoral approach has also been successful. It is not known whether percutaneous injection is as effective as the transoral approach. This article reviews our experience with both techniques of injection on 29 patients with adductor type SD. Since 1992, we have carried out 48 treatment sessions with the transoral technique and 76 treatment sessions with the percutaneous technique. Two patients did not respond to the percutaneous technique despite several attempts, but they did respond to the transoral approach. Globally, transoral technique was superior to percutaneous technique in terms of effectiveness (48 of 48 responses with transoral technique versus 61 of 76 responses with percutaneous approach, p < 0.01). Dosage of BT, duration, and side effects were similar with both techniques. This article also describes a simple, inexpensive device, composed of materials on hand at every hospital, that facilitates the transoral approach.