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Detailed experimental results are presented for both laminar and turbulent flow of aqueous solutions in pipes of different diameters. Nonelectrolytes, such as sugar solutions followed the normal Moody pressure loss curves. Drag enhancement was demonstrated for turbulent flow of aqueous electrolyte solutions but not for laminar flow. The increased pressure drop for turbulent electrolyte flow was attributed to an electroviscous effect and a theory was developed to explain the drag enhancement. The increased pressure drop for the turbulent region of flow was shown to depend on the Debye length in the laminar sublayer on the pipe wall. Reasonable predictions of the increasing drag were obtained for both 1:1 and 2:1 electrolyte solutions.

In this study, the levels of the cysteine proteinase--cathepsin B were measured in diseased synovial fluids using a steady state fluorometric assay. Cathepsin B-like activity was shown to be present in all the samples analysed, with the rheumatoid arthritic synovial fluids possessing significantly higher concentrations (mean value ca. 416 mg/l) than the osteoarthritic fluids (mean value ca. 142.4 mg/l). In addition, upon treatment with pepsin, all of the rheumatoid arthritis samples were shown to possess additional cathepsin B-like activity, suggesting the presence of a reservoir of latent precursor molecules. By utilising a recently developed biotinylated affinity label for cathepsin B-like proteinases and sheep anti-(human cathepsin B) antibodies, used in combination with SDS-PAGE and Western blotting, the rheumatoid arthritic synovial cathepsin B was shown to exist in two forms with apparent molecular masses of M(r) 29,000 and 42,000. We propose that the former is a functionally active proteinase, whereas the latter is a pepsin activatable proform which, when cleaved by this aspartyl proteinase, is converted into a catalytically competent species of M(r) 20,000.

1. A 1H-n.m.r. method was used to measure concentrations of valine, alanine, lactate, acetate, hyaluronan and lipids in synovial fluid obtained, during the normal course of examination from the knee joints of patients attending rheumatology and orthopaedic clinics. Fluid was available from 16 patients with osteoarthritis, 18 patients with rheumatoid arthritis, four patients with meniscal tear and one patient each with systemic lupus erythematosis, mono-arthritis, synovitis and loose bodies. Four normal specimens were obtained for comparison. 2. Valine, alanine and acetate levels all showed a normal Gaussian distribution, reflecting the distributions within the serum of the sample population. 3. Lactate concentrations divided into two distinct patterns. At concentrations below 2.5 mmol/l the lactate levels showed a Gaussian distribution, reflecting the distribution in normal serum. The normal synovial fluid specimens belong to this distribution. Above 2.5-3.0 mmol/l, lactate levels were asymmetric in distribution with a long tail at higher concentrations. These high levels of lactate can be explained by the generation of lactate through anaerobic metabolism within the synovial cavity. This metabolic process is triggered by a general inflammatory condition such as in rheumatoid arthritis. 4. The distribution of n.m.r.-observable lipid concentrations in rheumatoid arthritis and osteoarthritis each shows a normal distribution and the mean concentration is significantly higher in rheumatoid arthritis. 5. An increased n.m.r.-observable hyaluronan concentration is associated with an inflammatory situation. 6. It is concluded that raised levels of lactate and n.m.r.-observable hyaluronan and lipids are useful markers to aid the clinical distinction between rheumatoid arthritis and osteoarthritis.(ABSTRACT TRUNCATED AT 250 WORDS)

Saccharomyces cerevisiae cells immobilized in a calcium alginate fiber reactor were used as a source of alcohol dehydrogenase for the NAD(+)-to-NADH reaction. The reaction was catalyzed by enzyme in cells on the surface of the fiber. Internal diffusional effects were present. The enzyme cell concentration was optimized by harvesting cells finally grown under anaerobic conditions. The results were expressed as an apparent reaction rate constant that was independent of NAD(+) and excess ethanol concentration, was slightly affected by flow rate above a minimum value, and increased with immobilized cell concentration in the fiber. The reaction was complete after 6 to 7 h under optimal conditions of 36 degrees C and 9.5 pH. The latter was 0.5 pH units above the free enzyme optimum, indicating that microenvironmental effects were in evidence., ((c) 1993 John Wiley & Sons, Inc.)

Saccharomyces cerevisiae (yeast) cells were employed as a source of alcohol dehydrogenase in the NAD(+)-to-NADH reaction. The cells were immobilized in calcium alginate monofilament fibers and used in a biological reactor. The alginate could not be heat sterilized since temperatures above 80 degrees C caused the polymer chains to degrade. The same proved true for the high pH necessary for the reaction, but the alginate strength was increased by Ba(2+) solution treatment. X-ray probe analysis showed that about 30% of the Ca(2+) sites exchanged with the Ba(2+) ions. The Ba(2+) ions (as well as the Ca(2+) ions) permeabilized the cells and increased the reaction rate. Long term trials showed that Ba(2+) ions were slowly elutriated from the fiber biocatalyst, causing a drop in reaction rate. The trend certainly was reversible as far as the fiber was concerned. It is assumed that the permeabilization of the cells by the Ba(2+) ions was a reversible process.

A new technique is outlined for the rapid settling of yeast cells in fermentation media. The technique involved the addition of dense, inert particles (nickel powder) to a yeast suspension (Saccharomyces cerevisiae) at pH 4.5 and a rapid change of pH to 8.0-9.0. When the pH was changed large flocs formed immediately and settled rapidly, leaving a clear supernatant. On returning the pH to 4.5 the flocs were destroyed. This technique gave larger flocs and higher settling rates than the constant pH method, and much lower nickel/yeast ratios were required. Good flocculation also occurred in a fermentation medium. The technique was used to recycle yeast cells to a semicontinuous ethanol fermentation. Application of the technique to this and similar systems is discussed. The factors affecting yeast/inert powder flocculation are also discussed and a model is proposed to explain the observed experimental behavior for flocculation with a rapid change in pH.

A novel technique for settling microorganisms has been described. The technique involves adding a dense, inert powder to a suspension of microorganisms under conditions where flocculation of the microorganism with the inert poweder occurs. The flocs formed are small and relatively dense and settle rapidly. Suspensions of Saccharomyces cerevisiae yeast have been flocculated with several different inert seed materials achieving rapid settling and separations of up to 99.9%. Nickel powder was used as a seed material for most experiments described here, and iron sand showed promise as a cheaper seed for large-scale use. The degree of flocculation and cell separation obtained depended largely on the seed concentration and the components in solution. Temperature and pH had little effect. When the method was initially applied to a practical fermentation, flocculation was poor because of inhibiting compounds in the fermentation medium, but modification of the technique produced good flocculation in the medium.