Binding of 4-methyl umbelliferyl-α-D-glucoPyranoside to Vicia faba lectin: Fluorescence-quenching studies

On binding toVicia faba lectin, the fluorescence of 4-methylumbelliferyl-α-D-glucoPyranoside was quantitatively quenched showing that the interaction of 4-methylumbelliferyl-α-D-glucoPyranoside took Place in a binding environment. The binding of the fluorescent sugar was saccharide sPecific as evidenced by the reversal of 4-methylumbelliferyl-α-D-glucoPyranoside fluorescence quenching by D-fructose. The association constant,K _a, values for the 4-methylumbelliferyl-α-D-glucoPyranoside was determined by comPetition study emPloying reversal of fluorescence quenching of 4-methylumbelliferyl-α-D-glucoPyranoside by D-fructose. TheK _a value obtained for D-fructose was 1.07 ±0.03 X 10⁴ M^-1 and for 4-methylumbelliferyl-α-D-glucoPyranoside was 1.60 ±0.05 X 10⁴ M^-1 at 15°C. TheK _a values of 2.51 ±0.06 X 10⁴M^-1, l.26 ±0.02 X 10⁴ M^-1 and 0.56 ±0.01 X 10⁴M^-1, resPectively at 10°, 20° and 30°C were obtained from the ChiPman equation. The relative fluorescence quenching, ΔF _a, at infinite concentration of the free saccharide sites ofVicia faba lectin [P′] was 93.5% at 30°C and the binding constant for 4-methylumbelliferyl-α-D-glucoPyranoside lectin interaction as derived by Yank and Hanaguchi equation was 0.63 ±0.01 X 10⁴M^-1.     

Cloning and expression of the gene for a fibronectin-binding protein from Staphylococcus aureus.

The gene encoding the fibronectin-binding protein (FNBP) from Staphylococcus aureus strain 8325-4 was isolated from a gene bank in pBR322. The original clone, containing a 6.5-kb insert, gave a functional product present in the periplasm of Escherichia coli. Analysis of polypeptides isolated after affinity chromatography on fibronectin-Sepharose followed by ion-exchange chromatography revealed two gene products, 87 and 165 kd in mol. wt. The amino acid compositions of these two polypeptides and a native FNBP from S. aureus strain Newman were very similar. Antibodies raised against the native FNBP from strain Newman precipitated the 125I-labelled 165-kd polypeptide, and unlabeled 165- and 87-kd polypeptides as well as native FNBP inhibited the immunoprecipitation reactions. The region of the fnbp-gene encoding the fibronectin-binding activity has been identified and subcloned in an expression vector based on the staphylococcal protein A gene. The resulting product in E. coli is an extracellular fusion protein consisting of two IgG-binding domains of protein A followed by a fibronectin-binding region. The fusion protein binds to fibronectin and completely inhibits the binding of fibronectin to intact cells of S. aureus.     

Partial 1p monosomy in a physically and mentally retarded boy

An 8-year-old boy is reported with marked mental and physical retardation, microcephaly, hypertelorism, mongoloid palpebral fissures, hypoplasia of the maxillary portion of the face, and other discrete anomalies. Deletion of the distal portion of the short arm of the chromosome 1 and the karyotype 46,XY, del(1)(p33----pter) was detected.     

Long-term effects of low-level 239Pu contamination on murine bone-marrow stem cells and their progeny

The effects of long-term internal contamination with 13.3 kBq kg-1 239Pu injected intravenously were studied in 10-week-old ICR (SPF) female mice. Radiosensitivity of spleen colony-forming units (CFU-S) and 125IUdR incorporating into proliferating cells of vertebral bone marrow and spleens were determined in plutonium-treated and control animals one year after nuclide injection. The CFU-S in 239Pu-treated mice were more sensitive to X-rays (D0 = 0.52 +/- 0.01 Gy) than in controls (D0 = 0.84 +/- 0.02 Gy). 125IUdR incorporation into bone marrow and spleen cells was reduced after plutonium contamination. At one year following plutonium injection, the occurrence of chromosome aberrations was evaluated in metaphase figures of femoral bone marrow cells. The frequency of aberrations increased early after plutonium treatment, at later intervals it tended to decrease but not below the control level. While the relative numbers of vertebral marrow CFU-S decreased significantly, but only to 86 per cent of normal, cellularity of vertebral bone marrow, peripheral blood counts and survival of 239Pu-treated mice did not differ from the control data.     

Binding of laminin to oral and endocarditis strains of viridans streptococci.

Attachment of bacteria to the host tissue is regarded as a crucial step in the development of many types of infections. Recent studies by us and others have shown that matrix proteins which serve as adhesion proteins for eucaryotic cells may also be recognized by some bacteria. In the present communication, we report that several strains of viridans streptococci are able to bind to laminin. Most strains isolated from blood and heart valves of patients with endocarditis expressed laminin receptors, whereas only a few of the strains isolated from the oral cavity recognized this protein. This observation indicates that laminin binding might be an important factor in the pathogenesis of viridans endocarditis. Laminin binding to two strains (Streptococcus mitis UAB594 and UAB597) isolated from patients with endocarditis was characterized further. The bacterial cells expressed a limited number of laminin receptors (4 X 10(2) to 1 X 10(3) per cell) which bound the protein in a high-affinity interaction (Kd, 40 to 80 nM). This receptor of S. mitis UAB594 was heat labile and could be solubilized from bacteria by brief digestion with trypsin. Solubilized receptors which competed with cell-bound receptors for 125I-laminin could be adsorbed on laminin-Sepharose but not on Sepharose substituted with fibrinogen or fibronectin. Comparison of laminin receptors from S. mitis with those previously described for Streptococcus pyogenes suggest that different sites in the laminin molecule are recognized by the two bacteria and hence that the corresponding receptor molecules are not identical.     

Stability of Lanatoside C content in thein vitro propagatedDigitalis lanata clones

In vitro culture was established from shoot tips ofDigitalis lanata cotyledonous plants. The propagated plant material was rooted, transplanted into soil and grown under field conditions. Lanatoside C content was determined in a total of 20 clones and statistically evaluated by means of variance analysis of unequal-sized samples.In vitro clonal propagation ofD. lanata was found not to affect lanatoside C content. Drug level was dependent on a plant genotype.     

Biotransformation of 2-(4-methoxybenzyl)-l-cyclohexanone by cell cultures ofSolatium aviculare

During the search for compounds with insect juvenile hormone activity, the biotransformation of 2-(4-methoxybenzyl)-l-cyclohexanone, of 2-(4-methoxybenzyl)-l-cyclohexanone ethylene acetal and of both isomers of 2-(4-methoxybenzyl)-l-cyclohexanol by plant cells was examined. The compounds were metabolized by cell suspension culture of Solatium aviculare Forst. The reaction conditions were optimized and the metabolic products isolated and identified. A scheme of biotransformation pathway has been proposed.     

Model-based relationship between physicochemical properties and inhibitory potency of alkylating 2-furylethylenes on yeast glycolysis

Inhibitory effects of 35 2-furylethylenes, non-specific alkylating agents, on glycolysis in a respiratory mutant of Saccharomyces cerevisiae were correlated with their 1-octanol/water partition coefficients and the rate constants for reaction with 2-mercaptoacetic acid using physiologically based models. The simplest model explaining the data satisfactorily consists of two-step drug-receptor interaction involving reversible formation of a structurally non-specific non-covalent complex stabilized later covalently. The concentration of the free drug in the receptor surroundings was related to its initial concentration in external medium via a simple form of a disposition function constructed on the basis of time hierarchy of passive membrane transport, non-covalent binding to cell constituents and metabolic inactivation of the drug.     

Leukocyte-derived inhibitory activity in patients with myelodysplastic syndrome

Leukocyte-derived inhibitory activity inhibiting the entry of normal progenitor cells of granulocytes and macrophages (CFU-GM) into the S-phase of a cell cycle was investigated in 16 patients with different forms of myelodysplastic syndrome (MDS). The presence of this inhibitory activity was analysed in medium conditioned with low-density cells obtained from peripheral blood of MDS patients. The inhibition rate was measured by 3H-thymidine suicide technique with subsequent cultivation of pretreated cells in semisolid agar medium. Low-density cells from MDS patients of various types were studied: from the twelve patients with refractory anaemia (RA or RAS) only three were positive, one patient with chronic myelomonocytic leukaemia (CMML) was negative while one patient with refractory anaemia with excess of blasts (RAEB) and two patients with RAEB in transformation (RAEB-T) were positive with respect of the described test. In two patients with RA, who underwent a long-term investigation, the production of leukocyte-derived inhibitory activity preceded the development of disease into RAEB or RAEB-T. In five positive cases, supernatants were incubated with antiserum against human placental ferritin; with one exception, the inhibitory activity was neutralized.     

Expression of HLA-DR antigens on tumour cells does not contribute to skin reactivity to autologous cholesteryl hemisuccinate (CHS)-treated tumour cells in patients with metastatic melanoma

Summary Skin tests with autologous cholesteryl hemisuccinate (CHS)-treated and untreated cells were performed in ten metastatic melanoma patients. In the majority of cases evident reaction was noted with CHS-treated cells (9/10) while the reaction with untreated cells was mostly negative (7/10). Tumour cell suspensions used for skin tests were characterized for reactivity with monoclonal antibody TAL 1B5 detecting the HLA-DR alpha chain. There were no differences between CHS-treated and untreated cells with respect to HLA-DR expression and no correlation was found between grade of skin reaction to CHS-treated cells and the proportion of HLA-DR positive cells in the injected cell sample.