A modified titration technique for the evaluation of preservative effectiveness in liquid pharmaceutical preparations

The original titration technique proposed for testing preservatives in cosmetics was modified and used for the evaluation of preservative efficiency in liquid pharmaceutical preparations. The modified technique has demonstrated that while a product is bactericidal to a small microbial challenge, it can be bacteriostatic or even nutritional to a larger challenge level.     

Influence of an alternating magnetic field on the bactericidal effect of ionizing radiation

A study was made of the effect of alternating magnetic field (AMF) and ionizing radiation delivered separately or in a combination on the microorganisms differing in radio-resistance. AMF (240 and 750 E) had no pronounced bactericidal action. A synergistic increase in the sterilizing effect of ionizing radiation was demonstrated after incubation of irradiated bacteria in AMF. The radiation-magnetic technique is proposed for sterilization of preparations and articles made of non-thermoresistant materials which permits to decrease by 1.5 times the bactericidal dose of ionizing radiation.     

Variability of the lytic susceptibility of Neisseria gonorrhoeae to human sera.

The bactericidal activity of human sera for Neisseria gonorhoeae was studied. Sera were obtained from a group of patients with gonococcal infections who had acute urethritis, acute pelvic inflammatory disease, disseminated gonococcal infection, or who were asymptomatic carriers. The homologous and heterologous strains were tested with these sera. The development of serum bactericidal antibodies was not a universal event. With few exceptions, the susceptibility of a particular strain to human antibody and complement appeared to be largely independent of the particular person from whom the serum was obtained and was due instead to antigenic properties intrinsic to each individual strain. Lipopolysaccharide appeared to be the predominant antigen against which bactericidal antibodies were directed. The principal bactericidal antibody class was IgM. Blocking antibodies were not found to account for the lack of lytic activity. A correlation of bactericidal antibodies with protection from developing gonococcal infection could not be demonstrated in three pateints.     

Unique intermolecular bactericidal epitope involving the homosialopolysaccharide capsule on the cell surface of group B Neisseria meningitidis and Escherichia coli K1

The N-propionylated group B meningococcal polysaccharide mimics a unique bactericidal epitope on the surface of group B meningococci and Escherichia coli K1. This was confirmed when both the above organisms were able to absorb the bactericidal antibodies from a mouse-anti-N-propionylated group B meningococcal polysaccharide-tetanus toxoid conjugate serum. By using affinity columns it was possible to divide the conjugate antiserum into three distinct populations of both group B polysaccharide cross-reactive and non-cross-reactive antibodies, one of which contained most of the bactericidal activity. The cross-reactive (IgG1) antibodies were absorbed by an affinity column in which the group B polysaccharide was linked to the solid support by a long spacer arm, thereby isolating a population of non-cross-reactive (IgG1) antibodies. Surprisingly the above column also retained another population of non-cross-reactive (IgG2a) and (IgG2b) antibodies which contained most of the bactericidal activity. These latter antibodies were not absorbed by a similar group B polysaccharide-affinity column in which a short spacer arm was employed. Thus the above experiments not only effected a separation of highly bactericidal antibodies but also provided evidence that the long spacer arm is functional in the binding of the bactericidal antibodies to the affinity column. This indicates that the bactericidal epitope is mimicked by the group B polysaccharide in the presence of the long spacer arm, which supports the hypothesis that the epitope is polysaccharide-associated and is probably intermolecular in nature.     

The relation between the bactericidal activity of complement and the character of the bacterial surfaces

The bactericidal activity of sera not containing antibodies (sera from precolostral piglets and calves) was tested with strains of gram-negative bacteria with different surfaces. The accuracy of the method of bactericidal test was evaluated statistically the bactericidal unit of complement was defined for comparing the activity of sera of different animals and different species. Various methods used for estimating the character of bacterial surface were compared. It was found that the bactericidal activity of piglet sera is directly dependent on the content of complement in the sera tested and the character of the bacterial surface (in the R-form). In selected strains there is a correlation in all criteria characterizing the surfaces of bacteria, and their susceptibility to bactericidal activity of sera; in a group of 37 strains selected at random, correlation with only one of the surface characteristics (stability in solution after heating to 100°C for 1 hour) was found. In calf sera a component was found which increases the effect of complement to some strains (e.g.Shigella shigae). This component may by absorbed from the serum only in the presence of complement. The nature of this factor is discussed.     

Constitutive innate immunity is a component of the pace-of-life syndrome in tropical birds

We studied the relationship between one component of immune function and basal metabolic rate (BMR), an indicator of the 'pace-of-life syndrome', among 12 tropical bird species and among individuals of the tropical house wren (Troglodytes aedon), to gain insights into functional connections between life history and physiology. To assess constitutive innate immunity we introduced a new technique in the field of ecological and evolutionary immunology that quantifies the bactericidal activity of whole blood. This in vitro assay utilises a single blood sample to provide a functional, integrated measure of constitutive innate immunity. We found that the bactericidal activity of whole blood varied considerably among species and among individuals within a species. This variation was not correlated with body mass or whole-organism BMR. However, among species, bacteria killing activity was negatively correlated with mass-adjusted BMR, suggesting that species with a slower pace-of-life have evolved a more robust constitutive innate immune capability. Among individuals of a single species, the house wren, bacteria killing activity was positively correlated with mass-adjusted BMR, pointing to physiological differences in individual quality on which natural selection potentially could act.     

On-line visualization of the competitive behavior of antagonistic bacteria.

To study the interaction between cocultured Listeria monocytogenes and an antagonistic Leuconostoc strain producing an anti-Listeria bacteriocin, flow cytometry, a technique allowing on-line and real-time analysis, was used along with classical microbiological methods. Culture methods and flow cytometric measurements of the mixed culture over time point to a bactericidal action of the lactic acid-producing bacterial strain against L. monocytogenes cells.     

Photo-Irradiation of Proanthocyanidin as a New Disinfection Technique via Reactive Oxygen Species Formation

In the present study, the bactericidal effect of photo-irradiated proanthocyanidin was evaluated in relation to reactive oxygen species formation. Staphylococcus aureus suspended in proanthocyanidin aqueous solution was irradiated with light from a laser at 405 nm. The bactericidal effect of photo-irradiated proanthocyanidin depended on the concentration of proanthocyanidin, the laser irradiation time, and the laser output power. When proanthocyanidin was used at the concentration of 1 mg/mL, the laser irradiation of the bacterial suspension could kill the bacteria with a >5-log reduction of viable cell counts. By contrast, bactericidal effect was not observed when proanthocyanidin was not irradiated. In electron spin resonance analysis, reactive oxygen species, such as hydroxyl radicals, superoxide anion radicals, and hydrogen peroxide, were detected in the photo-irradiated proanthocyanidin aqueous solution. The yields of the reactive oxygen species also depended on the concentration of proanthocyanidin, the laser irradiation time, and the laser output power as is the case with the bactericidal assay. Thus, it is indicated that the bactericidal effect of photo-irradiated proanthocyanidin is exerted via the reactive oxygen species formation. The bactericidal effect as well as the yield of the oxygen radicals increased with the concentration of proanthocyanidin up to 4 mg/mL, and then decreased with the concentration. These findings suggest that the antioxidative activity of proanthocyanidin might prevail against the radical generation potency of photo-irradiated proanthocyanidin resulting in the decreased bactericidal effect when the concentration is over 4 mg/mL. The present study suggests that photo-irradiated proanthocyanidin whenever used in an optimal concentration range can be a new disinfection technique.     

Denatured bactericidal proteins: Active per se,or reservoirs of active peptides?

According to the structure-to-function paradigm proteins fold into a 3D structure for exerting their functions. Intrinsically destructured proteins with important biological functions have been identified and studied, but they assume a structure when interacting in the cell with their partners. There are instead bactericidal proteins, endowed also with other diverse activities (glycoside hydrolases, RNases, a defensin), which are lost when the proteins are denatured or inactivated, whereas the bactericidal activity is surprisingly conserved.The hypothesis is advanced that these proteins are not bactericidal per se, but because they store in their amino acid sequences peptide segments that display bactericidal activity when cut out as free peptides from the proteins. These bactericidal proteins would thus be merely containers of bactericidal peptides.     

Changes in the bactericidal activity of macrophages from mice with various degrees of resistance to Salmonella typhimurium infection as affected by interferon

The bactericidal activity of mouse macrophages with different sensitivity to Salmonella infection has been studied. The sensitivity of BALB/c mice to S. typhimurium infection is associated with the low bactericidal activity of their macrophages. The introduction of interferon stimulates the bactericidal activity of macrophages sensitive to Salmonella infection of mice, which sharply enhances the resistance of the animals to this infection.     

Production of Photons in the Bactericidal Effect of Transient Electric Arcs in Aqueous Systems

The radiation in the visible and ultraviolet regions from submerged, transient electrical arcs was measured with a K(3)Fe(C(2)O(4))(3) chemical actinometer and was compared to the bactericidal effect obtained with the same electrical arrangements. Photon production and bactericidal effect were obtained at lower voltages with a smaller electrode separation than with a wider one. At higher voltages, both increased with wider electrode separations. The voltages at maximal photon production efficiency coincided with those of maximal bactericidal efficiency. However, the same photon radiation produced by different electrical arrangements did not always yield the same bactericidal effect in the small discharge vessel usually employed. In a larger discharge vessel, the bactericidal effect was closely correlated with the photon production. The efficiency of photon production by transient arcs was smaller than that of germicidal mercury lamps, particularly with respect to wavelengths of great bactericidal activity. The mechanisms of inactivation and their use for practical disinfection purposes are discussed.     

The sensitivity of Hafnia alvei strains to the bactericidal effect of serum

Abstract Most Hafnia alvei strains are sensitive to the bactericidal action of normal bovine serum (NBS) as well as to a serum in which the alternative pathway of complement activation has been thermally blocked. Introduction of polysaccharides (PS) to NBS lowers the bactericidal effect. In a serum in which the alternative pathway of complement activation is blocked, PS completely cancels the bacterial effect.     

A comparative study of the bactericidal activity of horseshoe crab (Limulus polyphemus) hemolymph and vertebrate serum

This paper describes a partially heat-labile, naturally occurring bactericidal factor in cell-free hemolymph preparations obtained from Limulus polyphemus. This bactericidal activity has been shown to be directed against two Gram-negative bacteria, Escherichia coli and Klebsiella pneumoniae, whereas it had no effect on the Gram-positive bacteria tested, Micrococcus lysodeikticus and Staphylococcus aureus. Maximal bactericidal activity of this factor was observed at 30°C and pH 6.0. Since complement and antibody are required for antimicrobial activity in vertebrate sera, the activity of this factor in the presence of various complement inhibitors was assayed. The bactericidal activity of Limulus hemolymph is abolished by treatment with endotoxin; however, other anticomplementary substances were without effect. Limulus amebocyte lysate is known to contain protein which may be precipitated by endotoxin; it is possible that the reduction of bactericidal activity produced by endotoxin treatment may be caused by the denaturation of a bactericidal protein moiety produced by the hemocytes.     

Determination of the bactericidal strength of alveolar macrophages by using the NBT test

The NBT test on alveolar macrophages can be used for the indirect evaluation of their bactericidal potency. This test has made it possible to show that the development of the tuberculous process in the lungs is characterized by the increasing intensity of the reduction of NBT by alveolar macrophages, which indirectly indicates their considerable bactericidal potency. But 3-4 weeks after infection macrophages, though capable of considerable bactericidal action, do not react to stimulation by Mycobacterium tuberculosis.     

人类杀菌肽基因cDNA片段的克隆

采用RT－PCR方法,从慢性粒细胞白血病患者的外周血白细胞中扩增得到长度约为1.5kb的有类杀菌肽cDNA进一步得到长度约为600bp的该多肽的氨基端部分cDNA扩增产物,将上述两种长度的扩增产物分别克隆至pUCm-T载体中,为进一步开展该重组抗菌肽的表达和活性研究奠定了基础。     

Biphasic effect of gingipains from Porphyromonas gingivalis on the human complement system

Periodontitis is an inflammatory disease of the supporting structures of the teeth and is caused by, among other agents, Porphyromonas gingivalis. P. gingivalis is very resistant to killing by human complement, which is present in a gingival fluid at 70% of the serum concentration. We found that the incubation of human serum with purified cysteine proteases of P. gingivalis (gingipains) or P. gingivalis wild-type strains W83 and W50 resulted in a drastic decrease of the bactericidal activity of the serum. In contrast, serum treated with P. gingivalis mutants lacking gingipains (particularly strains without HRgpA) maintained significant bactericidal activity. To understand in detail the mechanism by which gingipains destroy the serum bactericidal activity, we investigated the effects of gingipains on the human complement system. We found that all three proteases degraded multiple complement components, with arginine-specific gingipains (HRgpA and RgpB) being more efficient than lysine-specific gingipain (Kgp). Interestingly, all three proteases at certain concentrations were able to activate the C1 complex in serum, which resulted in the deposition of C1q on inert surfaces and on bacteria themselves. It is therefore plausible that P. gingivalis activates complement when present at low numbers, resulting in a local inflammatory reaction and providing the bacteria with a colonization opportunity and nutrients. At later stages of infection the concentration of proteases is high enough to destroy complement factors and thus render the bacteria resistant to the bactericidal activity of complement.     

Bactericidal effect of Fe2+, ceruloplasmin, and phosphate.

Fe2+, when combined with ceruloplasmin or phosphate, was bactericidal to Escherichia coli at pH 5.0, and when Fe2+, ceruloplasmin, and phosphate were combined, a bactericidal effect was observed under conditions, i.e., short incubation period, in which Fe2+ plus ceruloplasmin and Fe2+ plus phosphate were ineffective. Bactericidal activity increased with the ceruloplasmin or phosphate concentration to a maximum and then decreased as their concentration was further increased. Fe2+ was oxidized in the presence of ceruloplasmin, phosphate, or, in particular, a combination of the two. A bactericidal effect was observed when there was only a partial loss of Fe2+, with more extensive oxidation resulting in a loss of bactericidal activity. The bactericidal effect of Fe2+ plus ceruloplasmin and/or phosphate was unaffected by catalase or superoxide dismutase and was not associated with iodination. Fe-EDTA was also bactericidal at an Fe2+: EDTA molar ratio of 1:0.5, where Fe2+ was partially oxidized. However, in contrast to Fe2+ plus ceruloplasmin and/or phosphate, bactericidal activity was inhibited by catalase and was associated with iodination. Combinations of Fe2+ and Fe3+ were not bactericidal under the conditions employed. A requirement for Fe2+ plus either a product of Fe2+ oxidation or an iron ceruloplasmin and/or phosphate chelate for bactericidal activity is proposed.     

Investigating the candidacy of LPS-based glycoconjugates to prevent invasive meningococcal disease: immunology of glycoconjugates with high carbohydrate loading

We investigated the immune responses of rabbits that were immunised with lipopolysaccharide (LPS)-based glycoconjugates by measuring the reactivity of the derived sera to a panel of selected wild-type and mutant strains of Neisseria meningitidis. In all cases, high titers of antibodies capable of recognising LPS elaborating the identical structure as presented on the immunising glycoconjugate were obtained, and in most cases the derived sera also recognised heterologous strains including wild-type, but at lower titers. However, although serum bactericidal antibodies were consistently obtained against strains elaborating the same LPS structure as the immunising antigen, this functional response was not observed against wild-type strains. We identified several potentially competing neo-epitopes that had been introduced via our conjugation strategies, which might compete with the conserved inner core oligosaccharide target region, thus reducing the antibody titers to epitopes which could facilitate bactericidal killing. This study has therefore identified key factors that are crucial to control in order to increase the likelihood of obtaining bactericidal antibodies to wild-type meningococcal cells with LPS-derived glycoconjugates. Glycoconjugates utilised in this study, have been found to contain epitopes that do not contribute to the derivation of antibodies that may facilitate bactericidal killing of wild-type strains and must be avoided in future LPS-based glycoconjugate preparations.     

Humoral immunity aspects of meningococcal infection. I. A method of performing and the characteristics of the immune bacteriolysis reaction]

Immune bacteriolysis test with meningococcus, group A, was used for the purpose of serum antibody study. Meningococcus cultures with a bright orange fluorescence of the colonies in oblique illumination (the I type) proved to possess the greatest lysability. Guinea pig serum sorbed with meningococcus suspension was found to be the best source of the complement. Sera obtained after 1 to 3 days of rabbit immunization, containing mostly IgM antibodies, had the greatest bactericidal capacity. Only those fractions which contained IgM possessed bactericidal activity in the hyperimmune rabbit sera with a high IgG antibody concentration. No lytic activity was displayed against meningococcus by unfractionated hyperimmune sera.     

经济杀菌灭藻剂OACL控制工业循环水中有害微生物的研究

研究了经济杀菌灭藻剂OACL对异氧菌、硫酸盐还原菌和铁细菌的杀菌作用。结果表明,在实验室条件下,其杀菌率平均为99％以上,在pH5和pH7时分别为97.8％和88％。而在现场投药试验条件下为92％以上。可以认为,OACL是一种新型的、经济的高效杀菌灭藻剂。