X-ray crystallographic studies of unique cross-linked lattices between four isomeric biantennary oligosaccharides and soybean agglutinin

Soybean agglutinin (SBA) (Glycine max) is a tetrameric GalNAc/Gal-specific lectin which forms unique cross-linked complexes with a series of naturally occurring and synthetic multiantennary carbohydrates with terminal GalNAc or Gal residues [Gupta et al. (1994) Biochemistry 33, 7495-7504]. We recently reported the X-ray crystal structure of SBA cross-linked with a biantennary analog of the blood group I carbohydrate antigen [Dessen et al. (1995) Biochemistry 34, 4933-4942]. In order to determine the molecular basis of different carbohydrate-lectin cross-linked lattices, a comparison has been made of the X-ray crystallographic structures of SBA cross-linked with four isomeric analogs of the biantennary blood group I carbohydrate antigen. The four pentasaccharides possess the common structure of (beta-LacNAc)2Gal-beta-R, where R is -O(CH2)5COOCH3. The beta-LacNAc moieties in the four carbohydrates are linked to the 2,3-, 2,4-, 3,6-, and 2,6-positions of the core Gal residue(s), respectively. The structures of all four complexes have been refined to approximately 2.4-2.8 A. Noncovalent lattice formation in all four complexes is promoted uniquely by the bridging action of the two arms of each bivalent carbohydrate. Association between SBA tetramers involves binding of the terminal Gal residues of the pentasaccharides at identical sites in each monomer, with the sugar(s) cross-linking to a symmetry-related neighbor molecule. While the 2,4-, 3,6-, and 2,6-pentasaccharide complexes possess a common P6422 space group, their unit cell dimensions differ. The 2, 3-pentasaccharide cross-linked complex, on the other hand, possesses the space group I4122. Thus, all four complexes are crystallographically distinct. The four cross-linking carbohydrates are in similar conformations, possessing a pseudo-2-fold axis of symmetry which lies on a crystallographic 2-fold axis of symmetry in each lattice. In the case of the 3,6- and 2,6-pentasaccharides, the symmetry of their cross-linked lattices requires different rotamer orientations about their beta(1,6) glycosidic bonds. The results demonstrate that crystal packing interactions are the molecular basis for the formation of distinct cross-linked lattices between SBA and four isomeric pentasaccharides. The present findings are discussed in terms of lectins forming unique cross-linked complexes with glycoconjugate receptors in biological systems.     

Heterogeneity of the human corticotropin-releasing factor-binding protein

Human corticotropin-releasing factor (hCRF), secreted by the placenta, principally in the third trimester, is specifically bound in the peripheral circulation to a 37-kDa binding protein (CRF-BP). This complex is cleared from the circulation. We postulate that the protein may be returned to the blood in a form that is immunologically altered and not well recognized by the reported RIAs. We report that a stable isoform can result from temporary denaturation of recombinant CRF-BP by 8 mol/L urea. This isoform, urea-treated binding protein, which can bind CRF, has been found to bind to an antibody raised against a synthetic peptide comprising the first 24 amino acid residues of CRF-BP, but not to a second similar N-terminal antibody, although it was closely matched in titer. Urea-treated binding protein also cross-reacts poorly in the RIA with CRF-BP. It is proposed that as a result of in vivo post-ligand binding events, isoforms may be susceptible to cleavage. After affinity purification, which involves denaturation, recombinant CRF-BP was often found to be cleaved after storage in the presence of protease inhibitors. Here we present evidence for a C-terminally truncated form of the native binding protein in the plasma of subjects suffering from rheumatoid arthritis, which may parallel the in vitro truncation.     

A Le Fort I osteotomy approach to lateral sphenoid sinus encephalocoeles

Meningo-encephalocoeles of the skull base may present as spontaneous cerebrospinal fluid rhinorrhoea or acute meningitis. Previous approaches to midline skull base lesions have been either intracranial, via a craniotomy, or by transfacial or endoscopic extracranial approaches. This paper presents an alternative approach to lateral sphenoid sinus encephalocoeles through a Le Fort I osteotomy approach.     

Clonal relationships among bloodstream isolates of Escherichia coli

The clonal relationships among 187 bloodstream isolates of Escherichia coli from 179 patients at Boston, Mass., Long Beach, Calif., and Nairobi, Kenya, were determined by multilocus enzyme electrophoresis (MLEE), analysis of polymorphisms associated with the ribosomal operon (ribotyping), and serotyping. MLEE based on 20 enzymes resolved 101 electrophoretic types (ETs), forming five clusters; ribotyping resolved 56 distinct patterns concordant with the analysis by MLEE. The isolates at each study site formed a genetically diverse group and demonstrated similar clonal structures, with the same small subset of lineages accounting for the majority of isolates at each site. Moreover, two ribotypes accounted for approximately 30% of the isolates at each study site. One cluster contained the majority (65%) of isolates and, by direct comparison of the ETs and ribotypes of individual isolates, was genetically indistinguishable from the largest cluster for each of two other collections of E. coli causing pyelonephritis and neonatal meningitis (R. K. Selander, T. K. Korhonen, V. V?is?nen-Rhen, P. H. Williams, P. E. Pattison, and D. A. Caugent, Infect. Immun. 52:213-222, 1986; M. Arthur, C. E. Johnson, R. H. Rubin, R. D. Arbeit, C. Campanelli, C. Kim, S. Steinbach, M. Agarwal, R. Wilkinson, and R. Goldstein, Infect. Immun. 57:303-313, 1989), thus defining a virulent set of lineages. The isolates within these virulent lineages typically carried DNA homologous to the adhesin operon pap or sfa and the hemolysin operon hly and expressed O1, O2, O4, O6, O18, O25, or O75 antigens. DNA homologous to pap was distributed among isolates of each major cluster, whereas hly was restricted to isolates of two clusters, typically detected in pap-positive strains, and sfa was restricted to isolates of one cluster, typically detected in pap- and hly-positive strains. The occurrence of pap-positive isolates in the same geographically and genetically divergent lineages suggests that this operon was acquired early in the radiation of E. coli, while hly and sfa were acquired subsequently, most likely by pap-positive and pap- and hly-positive precursors, respectively.     

Axotomy increases CNTF receptor mRNA in rat spinal cord

Chronic eosinophilic pneumonia (CEP) is a rare disorder of unknown etiology characterized by striking systemic and pulmonary manifestations such as fever, weight loss, blood eosinophilia, characteristic fluffy peripheral opacities on chest radiograph, and a prompt response to corticosteroid therapy. While the initial phase has been well documented, there is very limited information concerning the long-term natural history and treated course of this condition. We report the clinical and laboratory findings together with the long-term follow-up data on 12 patients with classic CEP who were followed up for a mean of 10.2 years (range, 4 to 13 years). The most striking feature of the long-term follow-up was the occurrence of relapses of CEP (often on multiple occasions) when corticosteroid therapy was discontinued or the dose was tapered. In those nine patients in whom steroid withdrawal was commenced, there was a clinical, hematologic, and radiologic relapse in seven (58 percent). However, prompt reinstitution of therapy led to a rapid resolution of symptoms. By contrast, two patients (17 percent) showed no evidence of relapse when steroid therapy was discontinued. A further three patients (25 percent) are maintained on a regimen of low-dose steroid therapy with no episodes of relapse. Reassuringly, all 12 patients are well at the end of a long period of follow-up. These data suggest that the long-term prognosis for patients with CEP is excellent but the majority will require long-term low-dose oral corticosteroid therapy in order to prevent relapse.     

The recycling of domestic waste water. A study of the factors influencing the storage capacity and the simulation of the usage patterns

The flushing of toilets with recycled domestic waste water makes a significant saving in the use of potable water. The size of the storage tank is a critical factor in the design of such a systeml the inputs to the storage, which are random, are influenced by the size of family and individual washing and bathing habits. The demand from the storage tank is random in time but the volume is constant at each occurence. A method of generating these waste water time series, with their inherent stochastic nature, is described. These simulated event patterns are then used to investigate the operation of a single-tank waste water storage system. The computer model determines the percentage of water conserved for several combinations of storage capacity and family size: the effect of changes in design parameters and operating conditions on the system performance is also assessed.