Antibacterial activity of particulate Bioglass® against supra- and subgingival bacteria

Particulate Bioglass is a bioactive material used in the repair of periodontal defects. This material undergoes a series of surface reactions in an aqueous environment which lead to osseointegration. The aim of this study was to determine whether these reactions exerted an antibacterial effect on a range of oral bacteria. Streptococcus sanguis, Streptococcus mutans and Actinomyces viscosus were suspended in nutrient broth (NB), artificial saliva (AS) or Dulbecco's modified eagle medium plus 10% foetal calf serum (DMEM + 10%FCS), with or without particulate Bioglass. All bacteria showed reduced viability following exposure to Bioglass in all the media after 1 h. This antibacterial effect increased after 3 h. Porphyromonas gingivalis, Fusobacterium nucleatum, Prevotella intermedia and Actinobacillus actinomycetemcomitans were suspended in either BM broth or 40% horse serum (HS) in RPMI. A considerable reduction in viability was observed with all bacteria tested, in both media, compared to inert glass controls. In further experiments it was found that the viability of S. sanguis was significantly reduced following exposure to NB pre-incubated with Bioglass. Additionally, it was found that neutralisation of this highly alkaline solution eliminated the antibacterial effect. Moreover, a solution of NB and NaOH (of equivalent pH) exerted an antibacterial effect of similar magnitude to that of the solution pre-incubated with Bioglass. Thus, particulate Bioglass exerts an antibacterial effect on certain oral bacteria, possibly by virtue of the alkaline nature of its surface reactions. This may reduce bacterial colonisation of its surface in vivo.

Structural and polypeptide differences between envelopes of infective and reproductive life cycle forms of Chlamydia spp

Significant differences in cysteine-containing proteins and detergent-related solubility properties were observed between outer membrane protein complexes of reproductive (reticulate body) and infective (elementary body) forms of Chlamydia psittaci (6BC). Elementary bodies harvested at 48 h postinfection possessed a 40-kilodalton major outer membrane protein and three extraordinarily cysteine-rich outer membrane proteins of 62, 59, and 12 kilodaltons, all of which were not solubilized by sodium dodecyl sulfate in the absence of thiol reagents. Intracellularly dividing reticulate bodies harvested at 21 h postinfection were severely deficient in the cysteine-rich proteins but possessed almost as much major outer membrane protein as did the elementary bodies. Most of the major outer membrane protein of reticulate bodies was solubilized by sodium dodecyl sulfate and was present in envelopes as monomers, although a proportion formed disulfide-cross-linked oligomers. By 21 to 24 h postinfection, reticulate bodies commenced synthesis of the cysteine-rich proteins which were found in outer membranes as disulfide-cross-linked complexes. The outer membranes of reticulate bodies of Chlamydia trachomatis (LGV434) also were found to be deficient in cysteine-rich proteins and to be more susceptible to dissociation in sodium dodecyl sulfate than were outer membranes of elementary bodies.

Longitudinal studies of types A and B influenza among Seattle schoolchildren and families, 1968-74

Longitudinal studies of influenza were conducted by postepidemic collection of sera and illness information among Seattle schoolchildren from 1968 to 1974 and in family groups from 1972 to 1974. The rate of infection with A/Hong Kong (H3N2) virus was lowest in the 1968-1969 epidemic; rates were twice as high in the epidemics of 1970 and 1972, and in the A/England (H3N2) epidemic of 1973. The introduction of a new strain of influenza type A or type B caused higher rates of infection in junior high than elementary schoolchildren. For influenza A, a shift in strain was associated with higher rates in the urban area than in the suburban area. The proportion of adolescents with serological evidence of infection who reported typical illness was 40%-42% in all three A/Hong Kong epidemics and 54% during the A/England epidemic. Reinfection with the A/Hong Kong strain was rare. Recent natural infection with the A/Hong Kong virus (1972) afforded 62% protection in the 1973 epidemic of A/England influenza.

Legionnaires' disease in a prepaid medical-care group in Seattle 1963--75

The community incidence of legionnaires' disease (L.D.) was estimated by a retrospective study of stored paired sera from 500 patients treated for pneumonia in Seattle in 1963--75. The patients were all members of a prepaid medical-care group; 84% were treated as outpatients. Only 5 (1%) had a fourfold rise in antibody titre to the L.D. antigen. Seroconversion to influenza A virus also occurred in 3 of the 5 cases. The course of illness in 4 of the 5 patients with confirmed infection was milder than that previously reported with legionnaires' disease. In addition, 1 child had a fourfold fall in titre, and 23 patients had titres of greater than or equal to 256 without significant change in titre. Only 8 of the 23 had their first serum collected later than 2 weeks after onset of illness, which suggests that the majority had acquired their antibodies before their attack of pneumonia. Prevalence of antibody in the 500 patients was not affected by age, sex, or year in which illness occurred. The incidence of legionnaires' disease based on 5 patients with rises in titre was estimated to be 0.4--2.8/10 000 persons/year.

Particulate Bioglass reduces the viability of bacterial biofilms formed on its surface in an in vitro model

45S5 Bioglass is a bioactive implant material which, in its particulate form, is used in the repair of periodontal defects. The surface reactions undergone by this material in an aqueous environment may exert an antibacterial effect that would be beneficial to periodontal surgical treatment. Biofilms of Streptococcus sanguis, an early plaque former, and mixed species biofilms from a salivary inoculum grown under conditions similar to those associated with periodontal implants, were grown on particulate Bioglass in a constant depth film fermenter (CDFF). Control biofilms were grown on inert glass particulates. At sample times of 3, 24 and 48 hours the viability of biofilms of S. sanguis grown on Bioglass was significantly lower than for those grown on inert glass. In the experiments with subgingivally-modelled mixed species biofilms, the total anaerobic counts were significantly lower on Bioglass after 24 and 48 hours, but not 96 or 168 hours, compared to inert glass. Thus, particulate Bioglass has the potential to reduce bacterial colonisation of its surface in vivo, a feature relevant to post-surgical periodontal wound healing.

Chlamydial DNA is absent from the joints of patients with sexually acquired reactive arthritis

The polymerase chain reaction was used to detect the presence of a plasmid essential for the growth of Chlamydia trachomatis. As few as 10 copies of the plasmid in the initial reaction mix were detectable using this technique. In contrast, chlamydial DNA was not detectable in the knee joints of nine patients with definite sexually acquired reactive arthritis (SARA) or nine patients with suspected SARA. Five patients with an undifferentiated seronegative lower limb oligoarthropathy, one with Crohn's disease and another with post-enteric reactive arthritis had evidence of intra-articular chlamydial antigens as judged by fluorescein-labelled monoclonal antibody staining of joint material but, again, no chlamydia plasmid DNA was detected. The nature of the immunofluorescent staining seen in some of these samples remains to be elucidated. It could be due to the presence of chlamydial outer membrane protein or lipopolysaccharide antigens in the joints, either free or in immune complexes, or it may be artefactual. Our results indicate that viable C. trachomatis is not present in the joints of the patients in this study even in the presence of chlamydial antigen detected by fluorescence antibody testing.

A Comprehensive Review of Topical Odor-Controlling Treatment Options for Chronic Wounds

The process of wound healing is often accompanied by bacterial infection or critical colonization, resulting in protracted inflammation, delayed reepithelization, and production of pungent odors. The malodor produced by these wounds may lower health-related quality of life and produce psychological discomfort and social isolation. Current management focuses on reducing bacterial activity within the wound site and absorbing malodorous gases. For example, charcoal-based materials have been incorporated into dressing for direct adsorption of the responsible gases. In addition, multiple topical agents, including silver, iodine, honey, sugar, and essential oils, have been suggested for incorporation into dressings in an attempt to control the underlying bacterial infection. This review describes options for controlling malodor in chronic wounds, the benefits and drawbacks of each topical agent, and their mode of action. We also discuss the use of subjective odor evaluation techniques to assess the efficacy of odor-controlling therapies. The perspectives of employing novel biomaterials and technologies for wound odor management are also presented.

Biofilm-specific surface properties and protein expression in oral Streptococcus sanguis

OBJECTIVE

Oral streptococci are primary colonisers of the tooth surface and are abundant in dental plaque biofilms. Bacteria growing in these relatively dense, surface-associated communities are phenotypically quite distinct from their planktonic counterparts. The purpose of the present study was to develop a method to investigate biofilm-specific surface protein expression by Streptococcus sanguis to help provide a better understanding of the critical events in plaque development.

DESIGN

Biofilm cells were grown on the surface of glass beads in a biofilm device fed with mucin-containing artificial saliva. Planktonic cells were grown in continuous culture at approximately the same growth rate. Surface hydrophobicity of biofilm and planktonic cells was determined by hexadecane partitioning, and expression of streptococcal fibronectin adhesin CshA was determined in ELISA using specific antiserum. Antisera raised to glutaraldehyde-fixed whole biofilm or planktonic grown cells were used to screen an expression library of S. sanguis genomic DNA, and isolated clones were sequenced.

RESULTS

Phenotypic analysis of biofilm and planktonic cells confirmed that mode of growth affected surface properties of S. sanguis. Thus, hydrophobicity and CshA expression was significantly elevated in biofilm cells. Library screening with biofilm antiserum yielded 32 recombinant clones representing 21 different S. sanguis proteins involved in adhesion and colonisation, carbohydrate utilisation or bacterial metabolism. In differential analysis of four selected Escherichia coli clones, biofilm antiserum reacted five times stronger than planktonic antiserum with cell-free extracts of clones encoding homologues of CshA and Cna collagen adhesin of Staphylococcus aureus, suggesting that these surface proteins are up-regulated in biofilm cells. In contrast, both antisera reacted equally strongly with cell-free extracts of the remaining two clones (encoding dihydrofolate synthase and an unknown protein).

CONCLUSIONS

The method described represents a useful means for determining bacterial protein expression in biofilms based on a combination of molecular and immunological techniques. Surface expression of putative fibronectin and collagen adhesins was up-regulated in biofilm cells.

Limited genetic diversity of Haemophilus influenzae (type b)

170 strains of Haemophilus influenzae (serotype b), isolated largely from patients with invasive disease from differing temporal and geographic origins were characterized using the combined approaches of DNA hybridization and outer membrane protein classification. Hybridization of a DNA probe to a region of the chromosome involved in the expression of type b capsular polysaccharide revealed that 163 (96%) isolates had one of three distinct, but closely related, chromosomal restriction fragment length polymorphisms (RFLPs). Each polymorphism was associated with its own distinctive set of outer membrane protein subtypes, indicating that the majority of H. influenzae (type b) isolates have evolved from common ancestors, giving rise to globally distributed organisms that have clonal characteristics.

Modulation by centrifugation of cell susceptibility to chlamydial infection

Enhancement of chlamydial infection of cell monolayers by centrifugation was shown to depend on induced cell surface changes. Evidence for this came from analysis of two forms of organism attachment which take place during centrifugation. In 'productive binding', organisms attached to cells and then entered and infected them. In 'unproductive binding', organisms became attached to cells but were not ingested. These organisms could be stripped from the cells by treatment with trypsin and could then infect fresh monolayers. Measurement of attachment kinetics during centrifugation showed that cells passed through three different susceptibility states. Only productive binding occurred in the first 20 min; cells then entered a refractory state during which no attachment took place At about 45 min, attachment recommenced but this allowed only unproductive binding. Induced movement of cell surface structures may enhance infection by promoting specific or non-specific interactions. Failure of ingestion may result from insufficient cell 'receptors' for circumferential binding of the whole chlamydial surface so that engulfment cannot take place.

Effects of long term denervation on smooth muscle of the chicken expansor secundariorum

Denervation of the expansor secundariorum muscle of the adult and 2 week chicken, by sectioning the brachial plexus, resulted in an approximate twofold increase in dry weight over 8 weeks. Unlike skeletal muscle, no ultrastructural changes were exhibited by the smooth muscle cells for a period of up to 5 months post denervation. No evidence of hypertrophy of the individual muscle cells was observed, but following colchicine treatment a definite increase in the number of mitotic figures was noted within muscle bundles indicating that the increase in dry weight of the expansor muscle is due to hyperplasia of the smooth muscle cells. The results are discussed in relation to in vitro studies of the interaction of sympathetic nerves with smooth muscle.

Amino acid requirements of strains of Chlamydia trachomatis and C. psittaci growing in McCoy cells: relationship with clinical syndrome and host origin

The effects of omission of individual amino acids from growth medium on the multiplication of a range of Chlamydia trachomatis and C. psittaci strains in cycloheximide-treated McCoy cells have been assessed. Differences in requirements were revealed which for C. trachomatis strains correlated with clinical syndrome and for C. psittaci with host origin. All 11 strains of C. trachomatis examined showed a requirement for addition of histidine to the medium; this was not shown by any of four C. psittaci strains. Among the strains of C. trachomatis, three from cases of trachoma, representing serotypes A, B and C, showed a distinctive requirement for the addition of tryptophan to the medium, whilst six strains of oculogenital origin, representing serotypes D-I, exhibited no requirement for tryptophan or methionine; a lymphogranuloma venereum and a 'fast variant' strain both showed a requirement for methionine. Of the four C. psittaci strains from different hosts, three showed distinct patterns of amino acid requirements. All chlamydiae required the addition of valine to medium and the majority required leucine, phenylalanine and also glutamine.

Differential amino acid utilization by Chlamydia psittaci (strain guinea pig inclusion conjunctivitis) and its regulatory effect on chlamydial growth

The effect of omission of individual amino acids from growth medium on the multiplication of Chlamydia psittaci (strain guinea pig inclusion conjunctivitis) in cycloheximide-treated McCoy cells has been examined. Marked differences were observed in the amounts of particular amino acids required for normal chlamydial multiplication: omission of either leucine, phenylalanine or valine completely inhibited multiplication, whereas absence of any one of another 10 amino acids had no effect on numbers of cells infected. Threshold concentrations of 80, 80 and approx. 8 nmol ml-1 for leucine, valine and phenylalanine, respectively, were needed for normal chlamydial multiplication. These requirements could not be related either to unusually high content in the whole organism, to degradation in the medium, or, from studies with leucine, to deficient association of leucine with host cells. Leucine deprivation at late stages of the developmental cycle also appeared to regulate multiplication. Possible mechanisms responsible for these effects are discussed.

Molecular cloning of the major outer membrane protein of Chlamydia trachomatis

A gene library of Chlamydia trachomatis (serovar L1) DNA has been prepared in the phage vector lambda 1059. From this bank, 20 recombinant phage-expressing components which reacted with serum from a patient with a C. trachomatis (L1) infection were chosen. Selective expression and radiolabeling of phage polypeptides in irradiated Escherichia coli demonstrated that one of these clones encoded a polypeptide doublet with an apparent molecular weight similar to that of the C. trachomatis (L1) major outer membrane protein. Both species of this cloned doublet (40 and 41 kilodaltons) could be immunoprecipitated by serum from a patient with a C. trachomatis (L1) infection but not by normal human serum. Components of this apparent molecular weight were not precipitated from irradiated E. coli infected with vector phage lambda 1059 by either of these sera. Comparison of the Staphylococcus aureus-V8 protease peptide maps of these two cloned polypeptides and chlamydial major outer membrane protein extracted from elementary bodies showed all three polypeptides to produce peptide fragments of 15.5, 13.8, and 11.5 kilodaltons. Due to the identical apparent molecular weights of the fragments produced from the 40- and 41-kilodalton cloned polypeptides, these were concluded to be different conformational forms of the same molecular species. These cloned components were indistinguishable from C. trachomatis (L1) major outer membrane protein.

Influence of cysteine deprivation on chlamydial differentiation from reproductive to infective life-cycle forms

The effects of omission of individual amino acids from growth medium on the differentiation of Chlamydia trachomatis DK-20 (serotype E) during infection of cycloheximide-treated McCoy cells are described. As judged by inclusion body staining with acridine orange, omission of cysteine from the medium severely retarded differentiation of reproductive reticulate body (RB) to infective elementary body (EB) forms. The effect appeared specific to cysteine in that omission of other amino acids had little or no effect on differentiation once RBs appeared. On restoration of cysteine, culture infectivity increased and inclusions contained organisms which, by cytochemical and morphological criteria, were differentiating to infective forms, indicating that cysteine deprivation did not irreversibly inhibit differentiation. Impairment of RB to EB differentiation in cysteine-less medium was also observed for three strains of Chlamydia psittaci and 10 other strains of C. trachomatis. It is suggested that the effect arises via the biosynthetic requirement for cysteine for provision of three cysteine-rich proteins, whose synthesis and insertion into the outer membrane have previously been shown to accompany RB to EB differentiation of C. psittaci 6BC and C. trachomatis 434 (serotype L2). Synthesis of cysteine-rich outer membrane proteins during differentiation may thus be common to all chlamydiae.

Differential neutralization of spontaneous and centrifuge-assisted chlamydial infectivity

Neutralization by specific antibody of a fast-killing variant strain of Chlamydia trachomatis, which showed high spontaneous infectivity for cell monolayers, was examined. It appeared that in spontaneous infection antibody-treated chlamydiae were neutralized by inhibition of attachment to cells. Centrifugation imposed a different effect: infection was inhibited at some step at or subsequent to attachment.

Influenza surveillance by age and target group

Surveillance for influenza virus infections began in mid-1976, continued through three small influenza A outbreaks (mixed A/Victoria and A/Texas outbreaks in Spring, 1977, and Winter, 1977-1978 and an A/USSR outbreak peaking in March, 1978). Nasopharyngeal specimens were collected for virus isolation from febrile respiratory disease patients coming from four sources: 1) the Sunday walk-in clinic of the Group Health Cooperative of Puget Sound; 2) 200 families under continuous surveillance for respiratory viral infections; 3) patients referred by interested community physicians or self-referred persons in vaccine evaluation studies; and 4) students presenting at the University of Washington health center. Influenza virus isolation rates were as high in children as adults and peaked earlier in adults than in children in all three epidemics. Although referred patients and university students yielded the highest isolation rate, nearly 30%, all four community sources were important in detecting an impending epidemic.

Association of Chlamydia trachomatis with mammalian and cultured insect cells lacking putative chlamydial receptors

The association of radiolabelled Chlamydia trachomatis (strains DK-20 and 434) with cultured cell monolayers has been examined. Previously, N-acetyl neuraminic acid and N-acetyl-glucosamine had been suggested to be involved in the association of certain strains of C. trachomatis with cultured cell monolayers. We have now studied the association of non-LGV (DK-20) and LGV (434) strains of C. trachomatis with cultured cells lacking these putative receptor components. Comparison of the association of strain DK-20 with McCoy or HeLa cells (containing sialic acids), with neuraminidase-treated McCoy or HeLa or with Aedes aegypti cells (all lacking sialic acids), surprisingly, showed enhanced binding to cells lacking the putative receptor component. Similarly, comparison of the association of chlamydial strain 434 with BHK-21 wild-type (containing N-linked N-acetylglucosamine) and BHK-21 RicR14 mutant cells (lacking this component) showed enhanced binding to the mutant cells.

Haemophilus influenzae serotype a: outer membrane protein classification and correlation with DNA polymorphism at the cap locus

Fifty-four temporally and geographically distinct isolates of Haemophilus influenzae serotype a were characterized by (i) outer membrane protein composition and (ii) DNA polymorphism at the cap locus. In 53 of 54 cases, knowledge of the outer membrane protein type was accurately predictive of the cap locus polymorphism, suggesting that the majority of H. influenzae (type a) isolates have evolved from a limited number of clones.

The perceived benefits of the enrolled nurse conversion course on professional and academic advancement

A study by Seccombe et al. (1997) for the United Kingdom Central Council (UKCC) found that seven in ten nurses who responded to their study perceived that there was no future for enrolled nurses (ENs). Conversion to first level registration is seen as a means by which ENs can progress in their career and there are an estimated 36 000 nurses who may still seek to convert. There is little evidence in the literature to indicate the value of conversion courses for ENs, yet Health Minister Alan Milburn plans to increase the number of places on conversion courses including funding 2700 places (Watson 1998). Evidence of the value of conversion would be helpful to individuals, teachers and managers rather than relying on anecdotal evidence of progress on which to judge its success or otherwise. The aims of conversion courses include the development of nursing knowledge, clinical skills and attitudes. In this study, a questionnaire is used to determine the perceived benefits to the individual who has undertaken a conversion course and the impact it has on career advancement, both professional and academic. The statements used are developed from a small exploratory study carried out by the authors (Allan & McLafferty 1999) in which it became clear that there were indeed positive changes in knowledge, skills and attitudes with as many as 90% of respondents having commenced or considering further study. The authors have broadened the study to include all Schools of Nursing and Midwifery who offer an EN conversion course in Scotland.

Host modification of chlamydiae: differential infectivity for cell monolayers of chlamydiae grown in eggs and monolayers

Cell monolayer-grown chlamydiae (CGO) differed from egg-grown organisms (EGO) in their increased spontaneous infectivity relative to centrifuge-assisted infectivity for monolayers. For each population spontaneous: centrifuge-assisted infectivity ratios were constant over a wide dose range. Spontaneous infection increased linearly with time and could not be exhausted from either population by prolonged adsorption; there was no change in infectivity ratios in residual supernatants. Further, one passage of EGO through monolayers gave CGO with stable infectivity properties not increased by further cell passage yet reverting on a single passage in eggs. Spontaneous infection of monolayers with EGO gave progeny with the same infectivity ratios as monolayers infected with EGO by centrifugation. The change in properties following EGO infection of monolayers occurred prior to natural release from cells. We conclude that EGO and CGO are two phenotypically distinct, homogeneous populations. The two infection modes are not properties of subpopulations within EGO and CGO. The relationship of these observations on chlamydiae to other possible host-imposed phenomena is considered.

Antibody response to influenza A/New Jersey and A/Victoria virus vaccines in 1976 and subsequent antibody levels after influenza A epidemics, 1977-1979

Antibody levels before and after vaccination were studied among schoolchildren and young adults given commercial A/New Jersey/76 (HswN1), A/Victoria/75 (H3N2), and B/Hong Kong/72 vaccines in the fall of 1976. Children responded better to a single dose of the A/New Jersey subvirion vaccine than had previously been observed, particularly to a new subvirion vaccine. Hemagglutination-inhibiting antibody titers decreased during the first six months after vaccination but appeared stable thereafter. Persistence seemed to depend on the antigenic mass in the first dose, since persons given one or two doses of the most potent whole-virus vaccine had by far the highest levels of antibody to A/New Jersey virus after 2 1/2 years, higher than for those given two doses of any of the other vaccines. Natural infection with A/USSR (H1N1) influenza virus boostered the titers of antibody to A/New Jersey virus, particularly in children. Persons given a bivalent subvirion vaccine had the best response to A/Victoria antigen. Subvirion vaccines induced complement-fixing antibodies in half of the children.

The road to conversion for enrolled nurses: a literature review

The literature concerning the plight of the enrolled nurse (EN) is extensive. This article examines published material from the last 10-12 years to consider the problems that ENs experience in relation to professional development and career advancement. For many ENs, conversion to first-level registration is seen as the only means of progress and possibly the only means of retaining a career. However, does conversion actually achieve progress? The literature on this subject is scarce but reports suggest that converted ENs do go on to achieve promotion and make use of educational opportunities (Crotty, 1990; MacGregor and Hill, 1996). Nevertheless, there is a substantial number of ENs who have no desire to convert to first-level registration and their role should be valued.