von Willebrand factor binds specifically to sulfated glycolipids

The human plasma glycoprotein Factor VIII/von Willebrand factor (vWF) binds specifically and with high affinity to sulfatides (galactosylceramide-I3-sulfate). vWF does not bind to gangliosides, neutral glycolipids, phospholipids, or cholesterol 3-sulfate. Although the largest oligomers of vWF bind preferentially to sulfatides, vWF monomers and dimers also bind but with reduced affinity. vWF binding is inhibited at high ionic strength or low pH, by some sulfated polysaccharides and by antibodies to vWF. Binding of vWF to sulfatides is probably responsible for its agglutination of aldehyde-fixed erythrocytes and may play a role in vWF-induced platelet adhesion or platelet aggregation.     

Monoclonal antibodies that recognize a polypeptide antigenic determinant shared by multiple Caenorhabditis elegans sperm-specific proteins

Four monoclonal antibodies that are directed against antigens present in sperm and absent from other worm tissues were characterized. Antibody TR20 is directed against the major sperm proteins, a family of small, abundant, cytoplasmic proteins that have been previously described (Klass, M. R., and D. Hirsh, 1981, Dev. Biol., 84:299-312; Burke, D. J., and S. Ward, 1983, J. Mol. Biol., 171:1-29). Three other antibodies, SP56, SP150, and TR11, are all directed against the same set of minor sperm polypeptides that range in size from 29 to 215 kD. More than eight different sperm polypeptides are antigenic by both immunotransfer and immunoprecipitation assays. The three antibodies are different immunoglobulin subclasses, yet they compete with each other for antigen binding so they are directed against the same antigenic determinant on the multiple sperm proteins. This antigenic determinant is sensitive to any of six different proteases, is insensitive to periodate oxidation or N-glycanase digestion, and is detectable on a polypeptide synthesized in vitro. Therefore, the antigenic determinant resides in the polypeptide chain. However, peptide fragments of the proteins are not antigenic, thus the determinant is likely to be dependent on polypeptide conformation. The antigenic determinant shared by these proteins could represent a common structural feature of importance to the localization or cellular specificity of these proteins.     

von Willebrand factor. A reduced and alkylated 52/48-kDa fragment beginning at amino acid residue 449 contains the domain interacting with platelet glycoprotein Ib

We have purified a reduced and alkylated tryptic fragment of von Willebrand factor (vWF) which migrated in sodium dodecyl sulfate-polyacrylamide gel electrophoresis as a 52/48-kDa doublet, but behaved as a single 46-kDa species after partial deglycosylation. After extensive treatment with denaturants, the 52/48-kDa polypeptide retained its ability to inhibit ristocetin-induced platelet aggregation in the presence of native vWF, as well as aggregation induced by desialylated vWF alone. Therefore, the 52/48-kDa polypeptide interacts with the platelet glycoprotein Ib receptor even in the absence of ristocetin. Both the 52/48- and the 46-kDa species inhibited ristocetin-induced binding of the intact molecule to platelets, but did not affect thrombin-induced binding. Determination of the NH2-terminal sequence of both members of the doublet gave identical results: VTLNPSDPEHCQ. This provided additional evidence that differences between the doublet constituents were only of carbohydrate composition and established the position of this peptide within the vWF polypeptide chain of approximately 2050 amino acid residues as beginning with the residue tentatively designated 449. These studies suggest that native conformation is not necessary for binding of vWF to platelets at the glycoprotein Ib receptor and that a linear amino acid sequence following residue 449 defines a domain responsible for this interaction.     

Systematic review of the Mastacembelidae or spiny eels of Burma and Thailand,with description of two new species ofMacrognathus

Burma and Thailand are inhabited by 14 species of Mastacembelidae, eightMacrognathus and sixMastacembelus. Two new species ofMacrognathus are described from Thailand, one with rostral toothplates and one without.Mastacembelus dayi, known only from Burma, is a valid species related toM. alboguttatus;Mastacembelus favus, from Thailand and Western Malaysia, is distinct from its close relativeM. armatus.     

Effect of chlorine dioxide on selected membrane functions of Escherichia coli

The mode of action of chlorine dioxide on Escherichia coli was assessed by studying outer membrane permeability to macromolecules and potassium, and observing effects on respiration. The results indicate that gross cellular damage involving significant leakage of intracellular macromolecules does not occur. There was a substantial efflux of potassium, however, and respiration was inhibited even at sublethal doses. It was concluded that the inhibition of respiration, which could be due to the damage to the cell envelope, was not the primary lethal event. Observations of the efflux of K⁺ strongly implicate the loss of permeability control as the primary lethal event at the physiological level, with nonspecific oxidative damage to the outer membrane leading to the destruction of the trans-membrane ionic gradient.     

Influence of dilution on the physical state of model bile systems: NMR and quasi-elastic light-scattering investigations

Multinuclear (1H and 31P) nuclear magnetic resonance (NMR) spectroscopy and quasi-elastic light scattering have been used to characterize molecular aggregates formed in dilute sodium taurocholate--egg lecithin solutions. When mixed micelles (1.25 g/dL) are diluted with 150 mM aqueous sodium chloride, light-scattering measurements suggest a transformation from mixed micelles to unilamellar vesicle species. Decreased 1H NMR line widths for bile salt resonances are consistent with predominance of a monomer form. The concurrent appearance of a second phospholipid choline methyl resonance indicates two types of phospholipid environment in slow chemical exchange: this behavior is consistent with small unilamellar vesicles. The appearance of bilayer vesicles in dilute model bile solutions is confirmed by addition of a lanthanide shift reagent (Pr3+), which splits the 1H or 31P head-group peak into two components with distinct chemical shift sensitivities. These mixed micelle and vesicle aggregates are also distinguished by their susceptibility to the lipolytic enzyme phospholipase A2 from cobra venom.     

Fine needle aspiration biopsy cytology in the diagnosis of inflammatory lesions

In 42 fine needle aspirations (FNA), the cytologic findings were interpreted as either suppurative or granulomatous inflammation. The majority of these FNAs were performed in patients with a known history of malignancy in whom recurrent or residual malignancy was suspected clinically. In 13 cases, a specific microbiologic diagnosis was made on the basis of the aspirate, either by cytology or by culture. In the remaining 29 cases, no specific diagnosis was possible. Open biopsies were later performed in 9 of the 29 cases, revealing the presence of actinomycosis of the parotid in one case and of carcinoma of the breast in a second. Five additional patients in whom only inflammation was diagnosed on the aspirate subsequently proved to have tumor at the FNA site. FNA therefore is not absolutely reliable for the exclusion of malignancy and requires correlation with other data and appropriate follow-up. Aspiration did, however, rapidly provide solutions to otherwise confusing clinical problems in the majority of instances.     

Collaborative study on the isolation of salmonella from artificially contaminated milk powder

The suitability of artificially contaminated milk powder as a substrate for salmonella reference samples and its stability under different storage conditions were studied. The need for a reconstitution step in the standard isolation method for salmonellas from milk powders was also investigated. When milk powder was examined in this way with a reconstitution step, differences in laboratory methods and/or storage times had no significant effect on the results after storage at 4 degrees C. With powder stored at room temperature there was a systematic decrease in the number of samples positive as the storage time increased. It is concluded therefore that milk powder contaminated with salmonellas should be stored at 4 degrees C. Examination of such milk powder with a reconstitution step yielded better results than without it and this step is therefore necessary for improving the reproducibility of the method. No significant differences were encountered between the standard isolation method and that used in the authors' laboratories. The results of this study indicate that milk powder is suitable as basic material for reference samples and that a reconstitution step should be included in the standard salmonella isolation procedure.     

Purification of a RecA protein analogue from Bacillus subtilis

We have identified in Bacillus subtilis an analogue of the Escherichia coli RecA protein. Its activities suggest that it has a corresponding role in general genetic recombination and in regulation of SOS (DNA repair) functions. The B. subtilis protein (B. subtilis Rec) has a Mr of 42,000 and cross-reacts with antisera raised against E. coli RecA protein. Its level is significantly reduced in the recombination-deficient recE4 mutant. B. subtilis Rec is induced 10- to 20-fold in rec+ strains following treatment with mitomycin C, whereas it is not induced in the recombination-deficient mutants recE4, recE45, and recA1. We have purified B. subtilis Rec about 2000-fold to near homogeneity and we describe its activities. It catalyzes DNA-dependent hydrolysis of dATP at a rate comparable to that of E. coli RecA protein. However, B. subtilis Rec has a negligible ATPase activity, although ATP effectively inhibits dATP hydrolysis. In the presence of dATP, B. subtilis Rec catalyzes DNA strand transfer, assayed by the conversion of phi X174 linear duplex DNA and homologous circular single-stranded DNA to replicative form II (circular double-stranded DNA with a discontinuity in one strand). ATP does not support strand transfer by this protein. B. subtilis Rec catalyzes proteolytic cleavage of E. coli LexA repressor in a reaction that requires single-stranded DNA and nucleoside triphosphate. This result suggests that an SOS regulatory system like the E. coli system is present in B. subtilis. The B. subtilis enzyme does not promote any detectable cleavage of the E. coli bacteriophage lambda repressor.     

Long-term reversible suppression of oestrus in bitches with nafarelin acetate, a potent LHRH agonist

Adult cyclic beagle bitches were treated for up to 18 months with nafarelin acetate via subcutaneously implanted osmotic pumps, starting during the first week of a pro-oestrous vaginal discharge. The imminent ovulation appeared to be unaffected by treatment, but doses of 8 or 32 micrograms analogue/day reduced the integrated luteal progesterone values. No new oestrus was detected in 3 bitches during 18 months of treatment with 32 micrograms/day, which resulted in mean plasma levels of 0.4 ng analogue/ml. A return to oestrus was observed in all 3 bitches between 3 and 18 weeks after cessation of treatment: 2 of the bitches mated at those times and produced normal litters. Another 2 bitches were similarly treated with 32 micrograms analogue/day; they were mated at the oestrus at start of treatment and dosing was continued for about 63 days. One of the bitches conceived and produced a normal litter. Nafarelin acetate treatment begun during anoestrus resulted in an induced heat 1-2 weeks after the start of treatment. The induced heat consisted of pro-oestrous vaginal discharge, oestrous vaginal cytology, and ovulation (judged by increased circulating levels of progesterone). Three bitches mated at the induced heat and treated for the normal duration of gestation did not litter. Nafarelin treatment of 3 bitches before puberty did not induce signs of oestrus and prevented the occurrence of oestrus through 18 months of treatment. The first oestrus in these bitches occurred 3.5-4 months after cessation of treatment, but mating at that time did not result in pregnancy. These studies have established the feasibility of and dosage requirement for the use of the LHRH agonist as a contraceptive in the bitch.