Testing of microbial demulsifiers with heavy crude emulsions

Summary It has already been demonstrated that model water-in-kerosene systems and toluene diluted heavy crude oil emulsions can be broken by microbial agents. In this studyN. amarae andR. rhodochrous are used on undiluted, water-in-heavy crude oil emulsions. The high viscosity of the undiluted emulsions severely limits the demulsifying ability of the bacteria towards these field emulsions.     

Chemokinetic accumulation of human neutrophils on immune complex-coated substrata: analysis at a boundary

The locomotory behavior of human blood neutrophil leukocytes was studied at a boundary between two surfaces with different chemokinetic properties. This was achieved by time-lapse cinematography of neutrophils moving on coverslips coated with BSA, then part-coated with immune complexes by adding anti-BSA IgG with a straight-line boundary between the BSA and the immune complexes. Cell locomotion was filmed in microscopic fields bisected by the boundary, and kinetic behavior was assessed by comparing speed (orthokinesis), turning behavior (klinokinesis), and the rate of diffusion of the cells on each side of the boundary, using a recently described mathematical analysis of kinesis. In the absence of serum or complement, the proportion of motile cells and their speed and rate of diffusion were greater on BSA than on antiBSA, but there was no consistent difference in turning behavior between cells on the two surfaces. The immune complexes were therefore negatively chemokinetic in comparison with BSA, and this resulted from a negative orthokinesis with little or no contribution from klinokinesis. As would be predicted theoretically, this resulted in gradual accumulation of cells on the immune complexes even in the absence of a chemotactic factor. In further studies, a parallel plate flow chamber was used to show that, under conditions of flow, neutrophils accumulated much more rapidly on a surface coated with BSA- anti-BSA than on BSA alone. Moreover, neutrophils on immune complex- coated surfaces lost their ability to form rosettes with IgG-coated erythrocytes. This suggests that neutrophils on immune complex-coated surfaces redistribute their Fc receptors (RFc gamma) to the under surface, and that the lowered speed of locomotion is due to tethering of neutrophils by substratum-bound IgG-Fc.     

Oxidation and chemical modification of lung beta-galactoside-specific lectin.

Galaptins are small, soluble, lectins with a specificity for beta-galactose residues. Many galaptins are inactivated by atmospheric oxygen and are protected by disulphide-reducing reagents. We find that each subunit of rat lung galaptin contains one residue of tryptophan and six of cysteine. Oxygen inactivates rat lung galaptin by oxidation of the cysteine residues. During oxidation, the normal dimeric structure is maintained and all disulphide bonds are formed within individual subunits. Exogenous thiols protect against inactivation, but oxidized thiols accelerate inactivation. Human lung fibroblast galaptin is almost completely inactivated within 1 h in tissue culture medium at 37 degrees C. Alkylation of native rat lung galaptin with iodoacetate or ethyleneimine causes substantial loss of activity. The dimeric galaptin structure is maintained. In contrast, alkylation with iodoacetamide yields carboxamidomethyl-galaptin, which is fully active and stable to atmospheric oxygen in the absence of disulphide-reducing reagents. This derivative is very useful for studies of galaptin properties and function.     

Ah receptor for 2,3,7,8-tetrachlorodibenzo-p-dioxin: ontogeny in chick embryo liver

Aryl hydrocarbon hydroxylase (AHH, cytochrome P1-450) is induced in chick liver very early during embryonic development if embryos are treated with 3-methylcholanthrene-type compounds such as 3,4,3'4'-tetrachlorobiphenyl. In mammals, AHH induction is known to be mediated by the Ah receptor. Liver from embryonic and newly hatched chicks was found to contain a cytosolic receptor for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) which has properties that are very similar to properties of the Ah receptor previously characterized in mammalian tissues. In chick embryo liver, cytosolic binding sites for TCDD were of high affinity (Kd for [3-H]-TCDD = 0.2 nM) and were specific for 3-methylcholanthrene-type inducers. The specific binding component sedimented at about 9S on sucrose density gradients prepared at low ionic strength. A high level of Ah receptor was detected in chick embryo liver by the fifth day of incubation (5 DI); this is at least 24 hours prior to the onset of AHH inducibility. The Ah receptor concentration increased from 5 DI to 8 DI, the period when chick liver is undergoing early morphological differentiation. After 8 DI, Ah receptor levels dropped substantially and remained low into the posthatching period. In contrast, AHH inducibility was high by 7 DI and remained high throughout embryonic development and into the posthatching period. The discrepancy between Ah receptor levels and the degree of AHH inducibility suggests that only a small fraction of the Ah receptor population is required for maximal AHH induction.     

The influence of contact guidance on chemotaxis of human neutrophil leukocytes

Chemotaxis of human neutrophil leukocytes moving on or in aligned 3D fibrin gels is more efficient if the cells are moving along the axis of fibre alignment than if they have to cross the fibres. This was shown by using two assays, one in which the cells were responding to a distant (600 micrometers) gradient source diffusing from a filter paper impregnated with formyl-Met-Leu-Phe and incorporated into the gel, the other in which the cells were responding to nearby (20--30 micrometers) Candida albicans spores in serum. In the former assay, impairment of chemotaxis across the axis of fibre alignment was highly significant. In the latter, cells showed efficient chemotaxis to the spores, but took more irregular paths when crossing the aligned fibres than when running along them. Neutrophils show contact guidance in aligned collagen or fibrin gels (Wilkinson et al., Exp cell res 140 (1982) 55) [1], thus the cells were subjected simultaneously to two directional cues in these experiments, one the chemotactic gradient and the other a contact guidance field. These cues may reinforce or interfere with each other depending on their relative orientation. Since many tissues in vivo show alignment or more complex forms of patterning, tissue architecture is likely to be an important determinant of the efficiency of cellular mobilization in inflamed or infected sites.     

Lipopolysaccharides from Pseudomonas maltophilia: composition of the lipopolysaccharide and structure of the side-chain polysaccharide from strain N.C.I.B. 9204

Lipopolysaccharide was extracted from defatted cell-walls of Pseudomonas maltophilia N.C.I.B. 9204. The major fatty acid components were 9-methyldecanoic acid, 2-hydroxy-9-methyldecanoic acid, 3-hydroxy-9-methyldecanoic acid, 3-hydroxy-dodecanoic acid, and 3-hydroxy-11-methyldodecanoic acid. Monosaccharide components of the phosphorylated core-oligosaccharide were D-glucose, D-mannose, D-galacturonic acid, 2-amino-2-deoxyglucose, and a 3-deoxyoctulosonic acid. The putative O-specific polysaccharide was composed mainly of 2-amino-2-deoxy-D-glucose, D-arabinose, and 6-deoxy-L-talose, but also contained an O-acetyl group and small proportions of rhamnose and 6-deoxy-3-O-methyltalose. Degradative and n.m.r. (1H and 13C) studies showed that the polymer had a branched trisaccharide repeating-unit with the following structure; the O-acetyl group was tentatively assigned to C-2 of the 6-deoxytalopyranosyl residue. (Formula: see text).     

Organ-related differences in binding of Dolichos biflorus agglutinin to vascular endothelium

We screened cryostat sections of tissues from 10 inbred strains of mice with a panel of conjugated lectins, in a search for polymorphisms which could be used as markers in mouse chimeras. In DDK and RIII mice, but not the other strains tested, there are binding sites on the membrane of vascular endothelial cells for Dolichos biflorus agglutinin (DBA), which is specific for terminal nonreducing N-acetyl galactosamine residues. The expression of DBA binding sites on RIII and DDK endothelium is not, however, uniform: there are consistent differences between blood vessels in different organs. These observations provide evidence of an organ-related heterogeneity in vascular endothelium which is open to biochemical analysis, and which raises the possibility that endothelial cells carry a “tissue address.”