Water disinfection by acoustic and hydrodynamic cavitation

The phenomena of cavitation which is associated with the formation, growth and the collapse of microbubbles, leads to the generation of very high pressures and temperatures locally, which can cause cellular damage. This paper explores the microbicidal effectiveness of cavitation for the disinfection of bore well water for potable use. Experiments performed in this study indicate that hydrodynamic cavitation is an energy efficient and economical technique compared to the other conventional non-chemical water treatment processes and cavitation was found to be a potential physical water disinfection technique for the production of potable water.     

Disruption of Brewers' yeast by hydrodynamic cavitation: Process variables and their influence on selective release

Intracellular products, not secreted from the microbial cell, are released by breaking the cell envelope consisting of cytoplasmic membrane and an outer cell wall. Hydrodynamic cavitation has been reported to cause microbial cell disruption. By manipulating the operating variables involved, a wide range of intensity of cavitation can be achieved resulting in a varying extent of disruption. The effect of the process variables including cavitation number, initial cell concentration of the suspension and the number of passes across the cavitation zone on the release of enzymes from various locations of the Brewers' yeast was studied. The release profile of the enzymes studied include alpha-glucosidase (periplasmic), invertase (cell wall bound), alcohol dehydrogenase (ADH; cytoplasmic) and glucose-6-phosphate dehydrogenase (G6PDH; cytoplasmic). An optimum cavitation number Cv of 0.13 for maximum disruption was observed across the range Cv 0.09-0.99. The optimum cell concentration was found to be 0.5% (w/v, wet wt) when varying over the range 0.1%-5%. The sustained effect of cavitation on the yeast cell wall when re-circulating the suspension across the cavitation zone was found to release the cell wall bound enzyme invertase (86%) to a greater extent than the enzymes from other locations of the cell (e.g. periplasmic alpha-glucosidase at 17%). Localised damage to the cell wall could be observed using transmission electron microscopy (TEM) of cells subjected to less intense cavitation conditions. Absence of the release of cytoplasmic enzymes to a significant extent, absence of micronisation as observed by TEM and presence of a lower number of proteins bands in the culture supernatant on SDS-PAGE analysis following hydrodynamic cavitation compared to disruption by high-pressure homogenisation confirmed the selective release offered by hydrodynamic cavitation.     

Study of physical and biological factors involved in the disruption of E. coli by hydrodynamic cavitation

Hydrodynamic cavitation results in flow restriction in a flow system causing rapid pressure fluctuations and significant fluid forces. These can be harnessed to mediate microbial cell damage. Hydrodynamic cavitation was studied for the partial disruption of E. coli and selective release of specific proteins relative to the total soluble protein. The effects of the cavitation number, the number of passes, and the specific growth rate of E. coli on the release of periplasmic and cytoplasmic proteins were studied. At the optimum cavitation number of 0.17 for this experimental configuration, 48% of the total soluble protein, 88% of acid phosphatase, and 67% of beta-galactosidase were released by hydrodynamic cavitation in comparison with the maximum release attained using multiple passes through the French Press. The higher release of the acid phosphatase over the total soluble protein suggested preferred release of periplasmic compounds. This was supported by SDS-PAGE analysis. The absence of micronization of cell material resulting in the potential for ease of solid-liquid separation downstream of the cell disruption operation was confirmed by TEM microscopy. E. coli cells cultivated at a higher specific growth rate (0.36 h(-1)) were more easily disrupted than slower grown cells (0.11 h(-1)). The specific activity of the enzyme of interest released by hydrodynamic cavitation, defined as the units of enzyme in solution per milligram of total soluble protein, was greater than that obtained on release by the French Press, high-pressure homogenization, osmotic shock, and EDTA treatment. The selectivity offered indicates the potential of enzyme release by hydrodynamic cavitation to ease the purification in the subsequent downstream processing.     

米氏凯伦藻溶血毒素的溶血反应特征

探讨了温度、pH值、二价阳离子等对米氏凯伦藻(Karenia mikimotoi Hasen)溶血毒素溶血活性的影响,分析了米氏凯伦藻溶血毒素的溶血反应特征.结果表明,实验室培养米氏凯伦藻的溶血活性约为64.69±6.43 HU L-1,单个藻细胞的溶血活性为6.17±0.61×10-6 HU;在实验温度(0～37℃)下,溶血活性随温度的增加而增加;pH6.0时的溶血活性最高;Cu2+、Mg2+、Mn2+、Ca2+、Co2+、Zn2+和Hg2+等对米氏凯伦藻的溶血活性的影响不同.离子浓度为5 mmol/L时,Hg2+的抑制作用最强.高浓度Hg2+对红细胞的集合效应不但阻止了Hg2+进入血细胞诱导的溶血作用,而且阻止了毒素对细胞膜的破坏,但这种抑制作用可被EDTA消除.     

The potential of hydrodynamic damage to animal cells of industrial relevance: current understanding

Suspension animal cell culture is now routinely scaled up to bioreactors on the order of 10,000 L, and greater, to meet commercial demand. However, the concern of the ‘shear sensitivity’ of animal cells still remains, not only within the bioreactor, but also in the downstream processing. As the productivities continue to increase, titer of ~10 g/L are now reported with cell densities greater than 2 × 10⁷ cells/mL. Such high, and potentially higher cell densities will inevitably translate to increased demand in mass transfer and mixing. In addition, achieving productivity gains in both the upstream stage and downstream processes can subject the cells to aggressive environments such as those involving hydrodynamic stresses. The perception of ‘shear sensitivity’ has historically put an arbitrary upper limit on agitation and aeration in bioreactor operation; however, as cell densities and productivities continue to increase, mass transfer requirements can exceed those imposed by these arbitrary low limits. Therefore, a better understanding of how animal cells, used to produce therapeutic products, respond to hydrodynamic forces in both qualitative and quantitative ways will allow an experimentally based, higher, “upper limit” to be created to guide the design and operation of future commercial, large scale bioreactors. With respect to downstream hydrodynamic conditions, situations have already been achieved in which practical limits with respect to hydrodynamic forces have been experienced. This review mainly focuses on publications from both the academy and industry regarding the effect of hydrodynamic forces on industrially relevant animal cells, and not on the actual scale-up of bioreactors. A summary of implications and remaining challenges will also be presented.     

Hemolytic Transfusion Reactions

After receiving apparently compatible blood three patients suffered hemolytic reactions. The compatibility tests were by saline and indirect Coombs technique including a screening tube of group 0 cells. The antibodies responsible for these reactions were not clearly demonstrable for several days following the transfusion. In two instances the antibody was anti-E.These case reports point up the following. (a) Currently used cross-matching procedures will occasionally fail to demonstrate an incompatibility. (b) In two of the cases the direct Coombs test was negative on an immediate post-transfusion specimen, when it could have been of great aid in diagnosis. (c) When a transfusion reaction of hemolytic type is suspected, a follow-up study several days after the reaction may clarify the diagnosis; when possible, transfusions should be avoided in the interim.     

The effect of acoustic cavitation on the contraction force and membrane potential of rat papillary muscles

Acoustic cavitation induced by continuous focused ultrasound (1.4 W/cm2, 543 Hz) was found to result in reversible membrane depolarization (by 54 mV), loss of excitability and contracture in the rat papillary muscles. The same intensities of impulse ultrasound had positive inotropic effects.     

Congenital Non-Spherocytic Hemolytic Anemia

A family with congenital non-spherocytic hemolytic anemia associated with glucose-6-phosphate dehydrogenase (G6PD) deficiency was studied. Two females, heterozygous for the enzyme deficency, had evidence of a hemolytic anemia. The results of chromium-51 erythrocyte life span studies prior to, during, and after periods of primaquine administration suggested that the hemolytic anemia in these women was due to the presence of two populations of red blood cells in their circulation. One population had normal G6PD levels and a normal life span, whereas the other had diminished enzyme activity and a shortened life span.In vitro metabolic studies of the erythrocytes of a heterozygous female and a hemizygous male suggested that, in spite of G6PD deficiency, the synthesis and breakdown of adenosine triphosphate and 2,3-diphosphoglyceric acid was similar to that in normal erythrocytes.     

Hemolytic activity of Serratia marcescens

A cell-bound hemolytic activity was found in several strains of Serratia marcescens. One Serratia cell per ten erythrocytes was sufficient to cause complete lysis of human erythrocytes within 2 h in the liquid assay. The hemolytic activity resided in the membrane fraction and could be inactivated by incubating cells with proteases. The hemolytic activity was greatly enhanced in actively metabolizing Serratia cells and was partially controlled by the iron supply. Hemolysis was accompanied by degradation of erythrocyte membrane proteins (band 3 and 6, glycophorin) and was independent of the blood group. The exoprotease secreted by S. marcescens in large amounts was not involved in hemolysis. Comparison with various hemolytic strains of Escherichia coli showed that hemolysis of erythrocytes was more pronounced with S. marcescens than with E. coli. In contrast to hemolysis by E. coli, lysis of erythrocytes by S. marcescens was not enhanced by Ca²⁺ ions.Dedicated to Professor Dr. Gerhart Drews on the occasion of his 60th birthday     

Shifts in morphometrics and their relation to hydrodynamic potential and habitat use during grayling ontogenesis

The theory of saltatory ontogeny predicts sudden morphological shifts during fish development which often occur simultaneously with physiological, anatomical or behavioural shifts. Therefore, our objectives were to identify potential sudden morphological shifts during grayling Thymallus thymallus ontogenesis and to check if these shifts affected the hydrodynamic potential of grayling in periods of known shifts in habitat use. In the 144 grayling studied (total length: 14·9–142·7 mm), three of 28 morphological variables considered revealed saltatory events during ontogenesis: position of maximal body height, position of maximal body width, and length to pelvic fin insertion. Using all variables (except total and standard length), five morphological groups were separated by multivariate analysis and each group had a particular hydrodynamic potential related to the drag of flow. Between these five different morphological groups, differences in the physical habitat use were observed. Basically, the saltatory pattern during grayling ontogenesis corresponded to a sequential habitat use that increased flow exposure and, simultaneously, to a stepwise improvement (at each habitat shift) of the hydrodynamic potential until the body had a shape that minimized drag of flow. The study confirms the theory of saltatory ontogeny for grayling in a context of flow physics and hydrodynamic adaptations.     

Hemolytic activity of hybrid antioxidants Ichphans

The hemolytic activity of new spatially hindered hybrid antioxidants—Ichphans—has been studied. The concentration-dependent hemolytic action of high concentrations of Ichphans with 8, 10, 12, or 16 carbon atoms in the aliphatic chain has been revealed. A nonmonotonic dependence of the hemolytic activity on the hydrophobic properties of Ichphans has been found.     

Hemolytic activities of stinging insect venoms

The direct hemolytic activities of the venoms from 21 species of stinging insects were determined. The activities spanned 3 1/2 orders of magnitude, ranging from a low of four to a high of 12,000 hemolytic units/mg dry venom, respectively, for the solitary wasp, Dasymutilla lepeletierii, and the social wasp, Polistes infuscatus. The latter activity is the highest reported for any insect venom and represents a level that is potentially harmful to humans stung by the wasp. The social wasps as a group generally possessed highly hemolytic venoms; the ants, poorly hemolytic venoms; and the solitary stinging species, venoms with extremely low activity. For the venoms, hemolytic activity correlated with neither lethal toxicity (LD₅₀) nor algogenicity. This finding suggests that hemolysins alone do not determine venom toxicity, and that the hemolysins of stinging insect venoms serve a variety of poorly understood roles. The range of activity of hemolysins from different venoms indicates they probably have different chemical structures and functions.