Lipid free radical generation and brain cell membrane alteration following nitric oxide synthase inhibition during cerebral hypoxia in the newborn piglet

Nitric oxide (NO) is reported to cause neuronal damage through various mechanisms. The present study tests the hypothesis that NO synthase inhibition by N(omega)-nitro-L-arginine (NNLA) will result in decreased oxygen-derived free radical production leading to the preservation of cell membrane structure and function during cerebral hypoxia. Ten newborn piglets were pretreated with NNLA (40 mg/kg); five were subjected to hypoxia, whereas the other five were maintained with normoxia. An additional 10 piglets without NNLA treatment underwent the same conditions. Hypoxia was induced with a lowered FiO2 and documented biochemically by decreased cerebral ATP and phosphocreatine levels. Free radicals were detected by using electron spin resonance spectroscopy with a spin trapping technique. Results demonstrated that free radicals, corresponding to alkoxyl radicals, were induced by hypoxia but were inhibited by pretreatment with NNLA before inducing hypoxia. NNLA also inhibited hypoxia-induced generation of conjugated dienes, products of lipid peroxidation. Na+,K+-ATPase activity, an index of cellular membrane function, decreased following hypoxia but was preserved by pretreatment with NNLA. These data demonstrate that during hypoxia NO generates free radicals via peroxynitrite production, presumably causing lipid peroxidation and membrane dysfunction. These results suggest that NO is a potentially limiting factor in the peroxynitrite-mediated lipid peroxidation resulting in membrane injury.     

Distinct promoter sequences of two precursor genes for salmon gonadotropin-releasing hormone in masu salmon

Three phase partitioning (TPP) uses t-butanol and ammonium sulfate to precipitate enzymes and proteins from aqueous solutions. The method is useful both upstream with crude samples and downstream where a scaleable simple step is needed. About 25 enzymes and proteins have been isolated by various laboratories using TPP-t-butanol. The relation of t-butanol used in TPP, with n-butanol used as an extraction agent from Morton's work, is reviewed. Some t-butanol appears bound to TPP-precipitated proteins which are actually protein-t-butanol coprecipitates. They float above denser aqueous salts because bound t-butanol increases their buoyancy, similar to the behavior of many lipoproteins. On redissolving TPP-precipitated enzymes, total and specific activities usually are regained and sometimes increased. Sulfate ion-in large concentrations-likely exerts itself through its kosmotropic action as in conventional salting out. t-Butanol likewise appears to be a kosmotrope and crowding agent at room temperature or above, whereas C1 and C2 cosolvents (e.g., ethanol) do not so behave except at near or below zero temperatures. However, kosmotropy is not the entire origin of TPP, nor probably of conventional salting out. Electrostatic forces, capacity to force protein conformation tightening and protein hydration shifts, also contribute. Electrostatic forces, and the tendency for salt ions to bind and tighten protein molecule conformation, are indicated by the sharp pH dependency of both conventional salting out and TPP, around pH regions where proteins undergo conformation changes. Sulfate anion is densely-perhaps extraordinarily-hydrated, adding much to its effective size, and therefore it has a tendency to crowd or exclude proteins, when sulfate concentrations are in the 0.5 to 3 M range.     

Molecular follow-up of disease progression and interferon therapy in chronic myelocytic leukemia

We previously reported that the abl promoter (Pa) undergoes de novo DNA methylation in the course of chronic myelocytic leukemia (CML). The clinical implications of this finding are the subject of the present study in which samples of CML patients, including a group treated with interferon alpha (IFNalpha) were surveyed. The methylation status of the abl promoter was monitored by polymerase chain reaction (PCR) amplification of the Pa region after digestion with several site-methylation sensitive restriction enzymes. Some 74% of the DNA samples from blood and marrow drawn in the chronic phase were nonmethylated, similar to control samples from non-CML patients. The remaining 26% were partially methylated in the abl Pa region. The latter samples were derived from patients who were indistinguishable from the others on the basis of clinical presentation. Methylated samples were mostly derived from patients known to have a disease of longer duration (26 months v 7.5 months, P = .01). Samples of 30 IFNalpha-treated patients were sequentially analyzed in the course of treatment. Fifteen patients with no evidence of Pa methylation before treatment remained methylation-free. The remainder, who displayed Pa methylation before treatment, reverted to the methylation-free status. The outcome is attributed to IFNalpha therapy, as the Pa methylation status was not reversed in any of the patients treated with hydroxyurea. Methylation of the abl promoter indicates a disease of long-standing, most likely associated with a higher probability of imminent blastic transformation. It appears to predict the outcome of IFNalpha therapy far better than the cytogenetic response.     

Partial cricotracheal resection with primary anastomosis in the pediatric age group

The traditional approach to severe subglottic stenosis (SGS) in the pediatric age group is laryngotracheal reconstruction (LTR). This approach may be complex and multistaged, with variable and unpredictable success rates in the individual patient. Excellent results have been reported in adults who had severe SGS and underwent partial resection of the cricoid and primary thyrotracheal anastomosis. This procedure has not been widely reported in infants and children. We report our experience with this procedure in 16 pediatric patients with grade III or IV SGS. Eleven patients had multiple previous LTR operations. The preoperative evaluation, surgical techniques, postoperative care, complications, and final results are described and discussed. Fourteen patients were decannulated after the procedure, 1 patient needed a second open procedure prior to decannulation, and 1 patient with concomitant bronchopulmonary dysplasia remains cannulated, for an overall 94% decannulation rate. Fourteen patients have no limitation of respiration, and 1 patient has moderate exercise intolerance. The results of this series suggest that partial cricotracheal resection with primary anastomosis is a relatively safe and effective procedure for pediatric patients with severe SGS.     

Task Planning For A Mobile Robot In An Indoor Environment Using Object-oriented Domain Information

For a mobile robot to be practical, it needs to navigate in dynamically changing environments and manipulate objects in the environment with operating ease. The main challenges to satisfying these requirements in mobile robot research include the collection of robot environment information, storage and organization of this information, and fast task planning based on available information. Conventional approaches to these problems are far from satisfactory due to their requirement of high computation time. In this paper, we specifically address the problems of storage and organization of the environment information and fast task planning in the area of robotic research. We propose an special object-oriented data model (OODM) for information storage and management in order to solve the first problem. This model explicitly represents domain knowledge and abstracts a global perspective about the robot's dynamically changing environment. To solve the second problem, we introduce a fast task planning algorithm that fully uses domain knowledge related to robot applications and to the given environment. Our OODM based task planning method presents a general frame work and representation, into which domain specific information, domain decomposition methods and specific path planners can be tailored for different task planning problems. This method unifies and integrates the salient features from various areas such as database, artificial intelligence, and robot path planning, thus increasing the planning speed significantly     

Evaluation of multicast routing algorithms for real-timecommunication on high-speed networks

Multicast (MC) routing algorithms capable of satisfying the quality of service (QoS) requirements of real-time applications will be essential for future high-speed networks. We compare the performance of all of the important MC routing algorithms when applied to networks with asymmetric link loads. Each algorithm is judged based on the quality of the MC trees it generates and its efficiency in managing the network resources. Simulation results over random networks show that unconstrained algorithms are not capable of fulfilling the QoS requirements of real-time applications in wide-area networks. Simulations also reveal that one of the unconstrained algorithms, reverse path multicasting (RPM), is quite inefficient when applied to asymmetric networks. We study how combining routing with resource reservation and admission control improves the RPM's efficiency in managing the network resources. The performance of one semiconstrained heuristic, MSC, three constrained Steiner tree (CST) heuristics, Kompella, Pasquale, and Polyzos (1992), constrained adaptive ordering (CAO), and bounded shortest multicast algorithm (BSMA), and one constrained shortest path tree (CSPT) heuristic, the constrained Dijkstra heuristic (CDKS) are also studied. Simulations show that the semiconstrained and constrained heuristics are capable of successfully constructing MC trees which satisfy the QoS requirements of real-time traffic. However, the cost performance of the heuristics varies. The BSMA's MC trees are lower in cost than all other constrained heuristics. Finally, we compare the execution times of all algorithms, unconstrained, semiconstrained, and constrained     

Substitution of an aspartic acid results in constitutive activation of c-kit receptor tyrosine kinase in a rat tumor mast cell line RBL-2H3

The c-kit protooncogene encodes a receptor tyrosine kinase that mediates signals required for differentiation, proliferation and survival of mast cells. We have already shown the constitutive activation of c-kit receptor tyrosine kinase (KIT) in a human mast cell leukemia line (HMC-1) and a murine mastocytoma cell line (P-815). We here examined whether such constitutive activation of KIT occurred in the rat tumor mast cell line RBL-2H3 as well, which is frequently used as a tool for studying functions of mast cells. In RBL-2H3 cells, KIT was constitutively phosphorylated on tyrosine and activated in the absence of autocrine production of its ligand, stem cell factor (SCF). Sequencing analysis revealed that one of c-kit genes of RBL-2H3 cells had a point mutation, resulting in amino acid substitution of Tyr for Asp in codon 817. When rat wild-type c-kit cDNA and mutant-type c-kit cDNA encoding KITTyr817 were transfected into cells of a human embryonic kidney cell line (293T), only mutant form KITTyr817 was constitutively phosphorylated on tyrosine and activated in the absence of SCF. Since mutations at the same Asp codon constitutively activated KIT in all the human HMC-1, murine P-815, and rat RBL-2H3 cell lines, and since the incorporation of antisense oligonucleotides of c-kit messenger RNA significantly suppressed the proliferation of RBL-2H3 cells, the activating mutations in the Asp codon of the c-kit gene appeared to be involved in neoplastic growth of mast cells.     

Attitudes of women of childbearing age towards prenatal diagnosis in southeastern France

The objective of this study was to explore women's attitudes towards prenatal diagnosis of trisomy 21 and to examine some of the factors possibly responsible for these attitudes before implementing in real practice serological screening of pregnant women at risk for trisomy 21. We carried out a telephone survey on a representative sample of women who had recently had a normal livebirth delivery in the Marseille district in 1990. The participation rate was 80 per cent and the average age of the mothers was 28.9 years. Among the 514 women interviewed, 78 per cent stated that they would ask for an amniocentesis for a 1 per cent risk of trisomy 21 at their next pregnancy. When adjusting for confounding factors, the decision to have or not to have an amniocentesis was found to depend not only on the women's attitude towards induced abortion, but also on their understanding of the risk involved and on the social context (knowing a handicapped child, discussion with the father). It also depended on the women's age and on what they knew about amniocentesis from the medical point of view. The risk of miscarriage can influence a woman's choice but this objection was not found to affect the women's decisions significantly in our survey. The data showed the existence of a high potential demand for fetal karyotyping.     

Anti beta 2glycoprotein I antibodies and lupus anticoagulant in patients with recurrent pregnancy loss: prevalence and clinical significance

Over 2000 electrocution deaths were identified among U.S. construction workers from 1980 to 1991, with the highest mean annual crude mortality rate (2.5 per 100,000 people), and second highest mean age-adjusted rate (2.7 per 100,000 people) of all industries. Although the crude fatality rates showed a downward trend, construction workers are still about four times more likely to be electrocuted at work than are workers in all industries combined. Nearly 40% of the 5083 fatal electrocutions in all industries combined occurred in construction, and 80% were associated with industrial wiring, appliances, and transmission lines. Electrocutions ranked as the second leading cause of death among construction workers, accounting for an average of 15% of traumatic deaths in the industry from 1980 to 1991. The study indicates that the workers most at risk of electrical injury are male, young, nonwhite, and electricians, structural metal workers, and laborers. The most likely time of injury is 11 a.m. to 3 p.m. from June to August. Focusing prevention on these populations and characteristics through better methods of worker and supervisor electrical safety training, use of adequate protective clothing, and compliance with established procedures could minimize the average annual loss of 168 U.S. construction workers.