27.5 W/m2 collection efficiency solar laser using a diffuse scattering cooling liquid: erratum.

In this erratum we clarify our previously published paper [Appl. Opt.57, 4008 (2018)APOPAI0003-693510.1364/AO.57.004008], where we used a solar spectrum truncated to a maximum wavelength of 830 nm in the numerical modelling, but did not state this in the paper. Here, we present a graph of the numerically modelled absorption in the Nd:YAG rod as a function of the diffuse reflectivity of the chamber walls using the full solar spectrum, confirming that the theoretical maximum possible absorption we predict is in agreement with literature values.

27.5 W/m2 collection efficiency solar laser using a diffuse scattering cooling liquid.

We report a solar pumped solid state laser using a 20 mm long, 3 mm diameter neodymium-doped yttrium aluminum garnet laser rod. This rod was placed in a liquid cooling chamber using a water-white-emulsion-paint mix. This mix provides cooling for the laser crystal and also doubles as a diffuse light scattering liquid. This enhances sunlight scattering and leads to a greater absorption in the laser rod. We numerically model the solar absorption in the laser rod using a ray-tracing model and predict a 2.6 times enhancement in absorption when a 98% reflective diffuse scatter is modelled compared to 0% scattering. We experimentally demonstrated this, showing a 2.58 times increase in average output power of the solar laser compared to the use of pure water as a cooling liquid. Using the water-white-paint scattering cooling liquid, we demonstrated a laser with an output power of 2.3 W and with a collection efficiency of 27.5 W/m2.

Interaction of Clostridium perfringens theta-haemolysin, a contaminant of commercial phospholipase C, with erythrocyte ghost membranes and lipid dispersions. A morphological study.

Commercially available preparations of phospholipase C from Clostridium perfringens are commonly contaminated with theta haemolysin, one of a group of bacterial haemolysins called oxygen labile (O-labile) haemolysins. Treatment of erythrocyte ghosts and a mixed lipid dispersion containing cholesterol with commercially available phospholipase C in the absence of Ca-2+ and the presence of phosphate buffer and/or EDTA resulted in the formation and release of ring or arc-shaped structures. Highly purified phospholipase C, free of theta-haemolysin, produced no changes in the morphology of erythrocyte ghosts or lipid dispersions in the presence of phosphate or EDTA, but caused the formation of typical diglyceride droplets in the presence of Ca-2+ in the absence of these inhibitors. Ring structures, identical to those caused by commercial phospholipase C, were formed on addition of highly purified theta-haemolysin to erythrocyte ghost membranes, lipid dispersions containing cholesterol and cholesterol dispersions, but not on treatment of membranes from Micrococcus lysodeikticus. Heat-inactivated O-haemolysin (60 degrees C for 10 min) produced no such effects. The dimensions of rings and arcs displayed heterogeneity. The outside diameters in various preparations varied from approx. 27-58 nm with border thickness of 4.1-7.8 nm.

Cyclophosphamide therapy for rheumatoid arthritis.

Cyclophosphamide in high doses was given for six months to 19 patients with rheumatoid arthritis. A second group of patients with rheumatoid arthritis whose conditions were stable on low-dose prednisone received in addition either cyclophosphamide or placebo for six months. Measurements of joint function and joint inflammation were used to estimate disease activity. Joint inflammation progressively decreased and joint function improved in the high-dose group. The low-dose cyclophosphamide-plus-prednisone group had a similar response that was different from the prednisone-plus-placebo group. Cyclophosphamide toxicity was common in the high-dose group and minimal in the low-dose-plus-prednisone group. Cyclophosphamide therapy improved the arthritis of these patients. The results were almost as good in the low-dose-plus-prednisone group, and the toxicity was much less.

Antirheumatic drugs: clinical pharmacological and therapeutic aspects.

There are many current concepts of the pathogenesis of rheumatic diseases which incorporate immunological, infectious and hereditary factors. Rheumatic diseases may sometimes become apparent after trauma, be associated with certain diseases and may be induced by nerve damage and serum sickness. Systemic lupuserythematosus may result from the use of a variety of drugs. At present the body of evidence tends to incriminate immunological factors as well as infectious agents as principal factors in the pathogenesis of rheumatoid arthritis and systemic lupus erythematosus. Just as there is uncertainty regarding the pathogenesis of rheumatic diseases, knowledge of the mechanism of action of the various drugs used to treat these diseases is also incomplete. Recent progress indicates that inhibition of prostaglandin biosynthesis and possibly lysosomal membrane stabilization are primary modes of action of the anti-inflammatory agents. Certain antirheumatic drugs have also been shown to exert some of their therapeutic effect by interfering with the kallikrein-kinin-kininase system...

Biotyping, serotyping and phage typing of Streptococcus faecalis isolated from dental plaque in the human mouth.

Thirty Streptococcus faecalis isolates from mixed dental plaque samples were classified into four groups on the basis of biotype, tetracycline susceptibility, phage type and serotype combinations. The organisms were from patients on haemodialysis, from staff of the dialysis unit, and from controls. Three biotypes were distinguished by seven biochemical tests: production of acid from inositol, sucrose and xylose; rapid or delayed production of acid from sorbitol; gelatin liquefaction; and production of alkaline phosphatase and beta-galactosidase. With a set of eight typing antisera for S. faecalis, 15 strains were non-typable, 12 were serotype 1 and three were serotype 19. With a set of 17 bacteriophages specific for S. faecalis, all of the oral isolates were typable; 40% were lysotype I1 and the remainder lysotype V6b. On the basis of biotype-serotype-phage-type combinations, indications of possible spread of strains between haemodialysis patients and dialysis unit staff were obtained. Biotyping and serotyping of 13 German isolates of S. faecalis of phage type I1 from four clinical sources and tripartite typing of three control strains provided additional evidence for the potential of biotyping in distinguishing between strains of identical serotype and phage type. One oral isolate of S. faecium was of phage type XX. None of the oral isolates of S. faecalis, of which 14 exhibited delayed sorbitol fermentation, reacted with group-G streptococcal grouping reagents or antiserum. Slow sorbitol fermentation does not appear to be a definitive phenotypic marker for S. faecalis strains possessing antigens that react with both group-D and group-G grouping reagents.

Fimbrial adhesins: similarities and variations in structure and biogenesis.

Fimbriae are wiry (2 to 4 nm diam.) or rod-shaped (6 to 8 nm diam.), fibre-like structures on the surfaces of bacteria which mediate attachment to host cells. Much has been learned in recent years about the biogenesis, structure and regulation of expression of these adhesive organelles in Gram-negative bacteria. Analyses of the genetic determinants encoding the biogenesis of fimbriae has revealed that the adhesive interaction of fimbriae can be mediated by major subunits (CFA/I and CS1 fimbriae) or minor subunits (P, S, and type 1 fimbriae), with the adhesin being located either at the tip of the fimbria or along the length of the fimbrial shaft. Minor subunits can also act as adapters, anchors, initiators or elongators. Post-translational glycosylation of the type 4 pilins of Neisseria gonorrhoeae, Neisseria meningitidis and Pseudomonas aeruginosa has been demonstrated. The structures of the PapD chaperone of Escherichia coli and of N. gonorrhoeae type 4 fimbrin have been resolved at 2.0-2.6 A. Rod-shaped fimbriae should not be thought of as being rigid inflexible structures but rather as dynamic structures which can undergo transition from a helicoidal to a fibrillar conformation to provide a degree of elasticity and plasticity to the fimbriae so that they can resist shear forces, rather like a bungee cord. At least four mechanisms have been identified in the assembly of fimbriae from fimbrin subunits, namely the chaperone-usher pathway (e.g., P-fimbriae of uropathogenic E. coli), the general secretion assembly pathway (e.g., type 4 fimbriae or N-methylphenylalanine fimbriae of P. aeruginosa, the extracellular nucleation-precipitation pathway (e.g., curli of E. coli) and the CFA/I, CS1 and CS2 fimbrial pathway.

Molecular analysis of Helicobacter pylori populations in antral biopsies from individual patients using randomly amplified polymorphic DNA (RAPD) fingerprinting.

In the present study, randomly amplified polymorphic DNA (RAPD) fingerprinting has been used to analyse multiple single colony isolates of Helicobacter pylori from antral biopsies in an attempt to ascertain whether or not multiple strains are present in individual patients using single biopsy samples. The RAPD fingerprints derived from single colonies obtained from the same biopsy specimen were in all cases indistinguishable. The previously noted heterogeneity between H. pylori strains from different individuals was confirmed. RAPD fingerprinting, combined with a simple method of template preparation, was shown to be an excellent method for H. pylori strain differentiation. The results of this study indicate that the H. pylori population is homogeneous in individual patients at a single gastric site.

Lack of a relationship between Lewis antigen expression and cagA, CagA, vacA and VacA status of Irish Helicobacter pylori isolates.

The cagA gene, vacA gene, CagA (cytotoxin-associated gene A product) and VacA (vacuolating cytotoxin) status of a collection of Helicobacter pylori isolates from the geographically distinct Irish population was determined, the potential association of these traits with Lewis (Le) antigen expression was assessed, and the relationship between these bacterial properties and the pathology associated with H. pylori infection was evaluated. Of the 57 isolates, a higher proportion from ulcer than from non-ulcer patients expressed VacA (71% vs. 53%). H. pylori isolates which were cagA-positive were no more significantly associated with peptic ulcers than non-ulcer disease (71% vs. 67%, P = 0.775), nor were CagA-positive isolates (57% vs. 50%, P = 0.783), but 80% of the isolates from duodenal ulcer patients were cagA-positive. Thirty-seven of the 57 isolates were tested for Le antigen expression. No statistically significant relationship (P > 0.05) was found between the occurrence and level of expression of Le(x) or Le(y) and cagA, vacA, or VacA status. This lack of an association in the Irish H. pylori isolates contrasts with that previously reported for predominantly North American isolates, and may be attributable to the adaptation of H. pylori strains with differing attributes to different human populations.

Development of intestinal antibodies against Escherichia coli antigens in piglets with experimental neonatal E. coli diarrhoea.

Intestinal immune responses to Escherichia coli antigens were studied in conventionally reared piglets orally infected on the first day of life with a virulent enterotoxigenic E. coli (O149: K88). During the first week of life intestinal antibodies were produced against the homologous lipopolysaccharide (LPS) as well as against the K88 antigen and the heat-labile enterotoxin (LT). On Day 7, anti-LPS antibodies of the IgA and IgG classes were detected in most piglets, whereas anti-K88 antibodies of the IgG and IgM classes predominated; antibodies against the enterotoxin were usually of the IgG class. In 21-day-old piglets antibodies of all immunoglobulin classes had usually been produced. In most cases, the levels of intestinal antibodies were substantially higher on Day 21 compared to Day 7, but the levels varied considerably both between and within litters. The intestinal immune responses did not correlate with the severity of clinical symptoms. One-, 7- and 21-day-old piglets reared in a specific-pathogen-free (SPF) herd lacked significant intestinal antibodies to the antigens examined. The oral challenge did not stimulate systemic immune responses. After colostral intake, all piglets had high antibody levels in the circulation. These levels decreased continuously during the 3-week study period. The possibility that high amounts of antibodies in colostrum could interfere with this early intestinal antibody formation should be considered when planning vaccination programmes against E. coli diarrhoea in piglets.

Carriage rates of enterococci in the dental plaque of haemodialysis patients in Dublin.

The incidence of carriage of enterococci in dental plaque was determined in haemodialysis patients attending three clinics in the Dublin area either as outpatients or as hospitalised patients. Their carriage rates were compared with a University group comprising normal healthy students, academic staff, technicians and ancillary personnel and with a cohort of otherwise healthy toothache patients. The carriage rates among the staffs of the dialysis units also were examined. The overall carriage rates of enterococci of the University group, the toothache patient group, the haemodialysis patients and the dialysis unit staffs did not differ significantly from each other, ranging from 5%-20%. However, the dental plaque of a mainly hospitalised group of haemodialysis patients and their attendant staff at one clinic was colonised to a statistically significant higher degree with enterococci than that of the haemodialysis patients and the staff at the outpatient clinics, both separately and as combined patient and staff groups. Age, sex, a history of recent antibiotic therapy, and elapsed time since the last dental visit did not affect isolation rates to a significant extent. The commonest enterococcus isolated from subjects was Streptococcus faecalis, followed by its variety liquefaciens. Only one subject harboured Streptococcus durans in dental plaque. Ten of the 21 subjects yielding enterococci harboured two different enterococci in their plaque. The isolation of S. faecalis var liquefaciens alone or in combination with S. faecalis did not correlate with subject-history parameters. The findings obtained imply that antibiotic prophylaxis specifically against enterococci may be necessary only for a small number of haemodialysis patients in whom oral carriage of enterococci has been demonstrated bacteriologically.

Legionella in Dublin hospital water supplies.

An environmental survey was carried out which consisted of periodic and random sampling of water tanks and showers in two large Dublin hospitals. Of the samples 5.3% yielded Legionella bacteria. Legionella pneumophila of serogroups 3, 5 and 6 were isolated from these sites with viable counts ranging from 3.0 x 10(2) - 2.5 x 10(3) c.f.u./litre. The implementation of periodic sampling may, however, not be a worthwhile exercise unless an environmental site has been associated with cases of legionellosis. Emphasis should be placed on the prevention of contamination of environmental sites with legionellae and on the development and implementation of protocols and procedures for the isolation of legionellae to gain the necessary expertise should an epidemiological survey be required.

Population characteristics of Irish Helicobacter pylori isolates: a tRNA-associated locus.

BACKGROUND: A strain-variable transfer RNA-associated-locus (trl) was present in 50% of Irish Helicobacter pylori (H. pylori), isolates and did not correlate with the origin of the isolates. AIM: To associate a particular genotype or phenotype to trl status in H. pylori by further screening the isolates from the original study for the presence of known genotypic and phenotypic characteristics. METHODS: Forty two clinical isolates were screened for the presence of the cagA, vacA, iceA1 and vapD genes by Southern or DNA dot blot analysis. Western blot analysis was performed using antibodies to CagA, VacA, Lewis X (Le(x)) and Lewis Y (Le(y)). Plasmids were identified by the alkaline lysis method. RESULTS: The cagA gene was present in 29 (69%) of isolates screened and 21 (50%) produced the CagA protein. The vacA gene was detected in all of the isolates while VacA was expressed in 71.4%. The iceA1 and vapD loci were detected in 73.8% and 71.4% respectively. Le(x) was expressed in 42.9% and Le(y) in 38.1% of the isolates. Expression of both Lewis antigens was detected in 7.1% while in 30.9% neither antigen was detected. Plasmids were present in 47.6%. There was no association between the trl status of isolates and any of the above. There were no significant associations between the phenotypic and genotypic characteristics studied and peptic ulcer disease or non-ulcer dyspepsia. CONCLUSION: The strain-variable tRNA-associated locus is independent of the vacA/VacA, cagA/CagA, Lewis X, Lewis Y, iceA1, vapD and plasmid status in the population of Irish H. pylori isolates studied.