Automatic updating of the EMBL database via EMBNet

The paper describes a procedure for updating the EMBL (European Molecular Biology Laboratory, Heidelberg) database of nucleic acid sequences and its indexes used by the University of Wisconsin Genetics Computer Group (GCG) software package, using updated entries for this database distributed via EMBNet. At present the procedure is being run on a MRC Clinical Research Centre's (CRC) SUN 4/280 server using SUNOS version 4.0.1 operating system.     

Age-dependent tetrahydrothiophenium ion formation in young children and adults receiving high-dose busulfan

Busulfan, a bifunctional alkylating agent, is a mainstay of myeloablative preparative regimens before hematopoietic stem cell transplantation. The apparent oral clearance of busulfan expressed relative to body surface area is 2-3-fold higher in children 1-4 years old than it is in adults. The first step in busulfan elimination is the formation of a tetrahydrothiophenium ion (THT+) in a glutathione S-transferase-catalyzed reaction. We present computer simulations that demonstrate that the ratio of the AUC of THT+ to that of busulfan over 6 h [(AUC(THT+)/AUC(BU))(0-->6)] is highly correlated (r2 = 0.805) with the determinants of THT+ formation and is virtually independent of the determinants of its elimination (r2 = 0.0201). We compared (AUC(THT+)/AUC(BU))(0-->6) determined in 14 children (0.5-4 years) to that of 11 adults (12-54 years) and found a 1.5-fold elevation in the area ratio (P = 0.0098) and a similarly significant increase in busulfan apparent oral clearance expressed relative to body surface area (P = 0.042). The only common explanation for the elevated busulfan apparent oral clearance and (AUC(THT+)/AUC(BU))(0-->6) is an enhanced ability of children to metabolize busulfan through glutathione conjugation.     

The influence of metal lattice vacancies on the oxidation of high temperature materials

When an oxide scale grows on a metal by the outward diffusion of cations, it is anticipated theoretically that lattice vacancies will be injected into the metal substrate. Experiments are reviewed which provide direct evidence for vacancy injection, including X-ray and electron microscope observations of the growth of vacancy dislocation loops and optical microscopy of voids. The influence of a vacancy supersaturation on the kinetics of oxidation is discussed in detail, but the effects are shown to be small in practical cases. The main consequence of vacancy injection is shown to be the eventual breakdown of the initial scale and subsequent growth of a duplex porous oxide. In some cases, this transition has undesirable consequences such as carburization/decarburization of the underlying metal and “breakaway” oxidation.     

Modeling of structural and compositional homogenization of plutonium-1 weight percent gallium alloys

The microstructure of as-cast Pu-1 wt pct Ga alloys is characterized by extensive Ga microsegregation often referred to as “coring”. This process results in grains that consist of Ga-rich cores (∼1.6 wt pct) with Ga-poor (∼0.1 wt pct) edges. Cored grains can be homogenized at moderately high (i.e., >400 °C) temperatures, though the time required to achieve chemical homogeneity is not well constrained. In this article, we apply several analytical diffusion modeling techniques to characterize the kinetics of alloy homogenization as a function of time and temperature. We also review the experimental investigations that have used analytical tools such as X-ray diffraction, density, dilatometry, and electron microprobe analysis to characterize Pu-Ga alloy homogenization. Data from these studies are used as a basis of comparison with modeling results. In particular, Ga coring-profile modeling appears to be a powerful tool for predicting alloy homogenization. FRANK E. GIBBS, formerly Technical Staff Member with the Nuclear Materials Technology Division, Los Alamos Laboratory     

Inhibition of cytochrome P-450 3A (CYP3A) in human intestinal and liver microsomes: comparison of Ki values and impact of CYP3A5 expression

Seckel syndrome has been described as the prototype of the primordial bird-headed type of dwarfism. Since Seckel originally defined the disorder, less than 60 cases have been reported. In addition to the characteristic craniofacial dysmorphism and skeletal defects, abnormalities have been described in the cardiovascular, hematopoietic, endocrine, and central nervous systems. This pleiotropy has implied genetic heterogeneity and prompted reviews of previously reported cases of Seckel syndrome. As a result, the characteristic diagnostic features of Seckel syndrome have been highly debated. Although deletions in chromosome 2q have been described, to date, no genetic defect has been defined. We report three cases of Seckel-like syndrome in siblings from nonconsanguinous Caucasian parents. In addition to the typical Seckel phenotypic features, all three cases were characterized by severe hydrocephalus. We review the literature and propose that there is a spectrum of Seckel conditions that share some common key features, but also demonstrate a wide range of phenotypic features.     

Groundwater Management in Drought-prone Areas of Africa

The issues pertaining to groundwaterdrought are reviewed with particular regard to the historical and present situations in Malawi, northern Ghana and the Northern Province of South Africa. These three quite different examples highlight some of the major difficulties facing respective governmentsand donor agencies, not least the shortcomingsof drought-reliefdrilling programmes,the general lack of routine monitoring and the need for longer term analysis and assessment of groundwatersystems than is currently possible. The distinct character of groundwater systems and their reaction to prevailing and changing environmentalconditions is discussed, and it is argued that essentially predictable variations in groundwater drought vulnerability are rarely planned for or acted upon. Managementissues arising are discussed and it is suggested that governments,and particularly donors, should place more emphasis on longer term, pre-droughtmitigation measures to reduce the need for costly and sometimes ineffective emergency interventions.     

The prevention pill

Eight children with the cyst of choledochus, ageing from 1 month to 15 years, were treated for the period of 20 years in clinic. Cystoduodenostomy is the method of choice for the treatment. All the patients have recovered.     

The UK Human Genome Mapping Project online computing service.

This paper presents an overview of computing and networking facilities developed by the Medical Research Council to provide online computing support to the Human Genome Mapping Project (HGMP) in the UK. The facility is connected to a number of other computing facilities in various centres of genetics and molecular biology research excellence, either directly via high-speed links or through national and international wide-area networks. The paper describes the design and implementation of the current system, a 'client/server' network of Sun, IBM, DEC and Apple servers, gateways and workstations. A short outline of online computing services currently delivered by this system to the UK human genetics research community is also provided. More information about the services and their availability could be obtained by a direct approach to the UK HGMP-RC.     

Intra-amniotic infection and premature rupture of the membranes

Antiphospholid antibodies (APL) have a notable association with recurrent miscarriages, arterial and venous thrombosis and thrombocytopenia. Analysis of the potential pathogenic effects of such human antibodies has been hampered by the considerable difficulty in producing IgG as opposed to IgM monoclonal immunoglobulins. We have developed four human monoclonal IgG APL (LJ1, AH2, DA3 and UK4) by fusing the peripheral blood lymphocytes of three patients with SLE with a mouse human heteromyeloma cell line, CB-F7. These antibodies bind to a variety of anionic phospholipids, two (LJ1 and AH2) bind total histones but none binds to ssDNA or dsDNA. Binding to beta 2 GPI is non-specific. UK4 alone demonstrates lupus anticoagulant activity. All four have lambda light chains, two are IgG1 (AH2 and UK4) and two are IgG3 (LJ1 and DA3). These APL utilize VH genes present in the fetally restricted repertoire and multiple somatic mutations in the CDR suggest an antigen-driven process. In contrast, there is no restriction in V lambda gene usage and only one lambda chain is extensively mutated. Two clonally related hybridomas were isolated from a single patients. This supports the theory that clonal expansion is the mechanism whereby antigen selects high affinity mutations.     

Functional mapping of the surface residues of human thrombin

Utilizing site-directed mutagenesis, 77 charged and polar residues that are highly exposed on the surface of human thrombin were systematically substituted with alanine. Functional assays using thrombin mutants identified residues that were required for the recognition and cleavage of the procoagulant substrate fibrinogen (Lys21, Trp50, Lys52, Asn53 + Thr55, Lys65, His66, Arg68, Tyr71, Arg73, Lys77, Lys106 + Lys107, Asp193 + Lys196, Glu202, Glu229, Arg233, Asp234) and the anticoagulant substrate protein C (Lys21, Trp50, Lys65, His66, Arg68, Tyr71, Arg73, Lys77, Lys106 + Lys107, Glu229, Arg233), interactions with the cofactor thrombomodulin (Gln24, Arg70) and inhibition by the thrombin aptamer, an oligonucleotide-based thrombin inhibitor (Lys65, His66, Arg70, Tyr71, Arg73). Although there is considerable overlap between the functional epitopes, distinct and specific residues with unique functions were identified. When the functional residues were mapped on the surface of thrombin, they were located on a single hemisphere of thrombin that included both the active site cleft and the highly basic exosite 1. No functional residues were located on the opposite face of thrombin. Residues with procoagulant or anticoagulant functions were not spatially separated but interdigitated with residues of opposite or shared function. Thus thrombin utilizes the same general surface for substrate recognition regardless of substrate function although the critical contact residues may vary.