The inability of Streptococcus mutans and Lactobacillus acidophilus to form a biofilm in vitro on dentine pretreated with ozone

Background: The use of ozone therapy in the treatment of dental caries is equivocal. The aim of this study was to use an in vitro model to determine the effects of prior ozone application to dentine on biofilm formation and to measure any associated reduction in bacteria viability. Methods: Twenty dentine discs were bonded to the bases of 5 mL polycarbonate screw top vials. Ten dentine discs were infused with ozone for 40 seconds, 10 samples remained untreated as a control. The vials were filled with nutrient medium, sterilized and placed into the outflow from a continuous chemostat culture of Streptococcus mutans and Lactobacillus acidophilus for four weeks. At the conclusion of the experiment bacterial growth was monitored by taking optical density readings of the growth medium in each vial and the outer surface of the dentine specimens were examined by scanning electron microscopy as shown by SEM analysis. Results: Ozone infusion prevented biofilm formation on all the treated samples while there was substantial biofilm present on the control specimens. While the average optical density of the control specimens was almost twice that of the ozone infused dentine (0.710 for the control with a SD of 0.288 and 0.446 for the ozonated samples with a SD of 0.371), the results were not significant (p > 0.05). Conclusions: This preliminary study has shown that the infusion of ozone into non‐carious dentine prevented biofilm formation in vitro from S. mutans and L. acidophilus over a four‐week period. The possibility exists that ozone treatment may alter the surface wettability of dentine through reaction with organic constituents.     

9-(3,4-dihydroxybutyl)guanine, a new inhibitor of herpesvirus multiplication

A new compound, 9-(3,4-dihydroxybutyl)guanine, has been synthesized and its antiherpes activity determined. 9-(3,4-Dihydroxybutyl)guanine was selectively phosphorylated by herpes simplex virus thymidine kinase and had a high affinity for this enzyme, with an inhibition constant of 1.5 microM. In cell culture, replication of different strains of herpes simplex virus types 1 and 2 was inhibited to the extent of 50% by 4 to 18 microM (RS)-9-(3,4-dihydroxybutyl)guanine. The (R)-enantiomer of this compound was more inhibitory than the (S)-enantiomer. Herpesvirus DNA synthesis was selectively inhibited by (RS)-9-(3,4-dihydroxybutyl)guanine in infected cells, and a low cellular toxicity was observed. (RS)-9-(3,4-Dihydroxybutyl)guanine had a therapeutic effect when applied topically to guinea pigs with cutaneous herpes simplex type 1 infections and to rabbits with herpes keratitis. Oral treatment of a generalized herpes simplex type 2 infection in mice had a therapeutic effect.     

Immunomodulatory Effects of Oak Dust Exposure in a Murine Model of Allergic Asthma

Repeated airway exposure to wood dust has been reported to causeadverse respiratory effects such as asthma and chronic bronchitis.In our recent study, we found that exposure of mice to oak dustinduced more vigorous lung inflammation compared to birch dustexposure. In the present study, we assessed the immunomodulatoryeffects of repeated intranasal exposure to oak dust both innonallergic and in ovalbumin-sensitized, allergic mice. Allergen-inducedinflux of eosinophils and lymphocytes was seen in the lungsof allergic mice. Oak dust exposure elicited infiltration ofneutrophils, lymphocytes, and macrophages in nonallergic mice.Interestingly, oak dust–induced lung neutrophilia as wellas oak dust–induced production of the proinflammatorycytokine TNF- and chemokine CCL3 were significantly suppressedin allergic mice. On the other hand, allergen-induced expressionof IL-13 mRNA and protein was significantly reduced in oak dust–exposedallergic mice. Finally, allergen-induced airway hyperreactivityto inhaled metacholine was significantly suppressed in oak dust–exposedallergic mice. The present results suggest that repeated airwayexposure to oak dust can regulate pulmonary inflammation andairway responses depending on the immunological status of theanimal.     

Controlled trial of continuous inflating pressure for hyaline membrane disease

A controlled trial of elective intervention with continuous inflating pressure (CIP) was performed in infants with severe hyaline membrane disease who weighed more than 1000 g at birth. Infants entered the trial if their arterial oxygen tension (PaO2) fell below 60 mmHg while breathing a fractional inspired oxygen concentration (F1O2) greater than 0-95. 11 out of 12 infants in the CIP-treated group and 10 out of 12 in the control group survived. 7 treated and 6 control infants required mechanical ventilation. When CIP was started the Pao2 of the treated infants increased, and they breathed high concentrations of oxygen for a significantly shorter period than the control infants. During the 31-month duration of the trial 107 other infants with severe hyaline membrane disease were admitted who did not meet the criteria for entry to the trial. 37 survived after breathing high concentrations of oxygen (F1O2 greater than 0-60) spontaneously without any ventilatory assistance, and the remaining 70 infants were already being ventilated on their arrival in the unit, usually because they had required mechanical ventilation during transfer from other hospitals. The neonatal survival rate for those infants born in this hospital during the study period was 88% (50 out of 57 infants) and for those referred from other hospitals it was 69% (51 out of 74 infants). The maximum further increase in overall survival rate that might have been achieved in our population of infants if CIP had been initiated very early in the course of the illness was 5%--i.e. from 77% (101/131) to 82% (107/131).     

Maternal HIV infection, drug use, and growth of uninfected children in their first 3 years

OBJECTIVE: To determine the separate effects of maternal HIV infection and drug use during pregnancy on growth of uninfected children in their first 3 years. DESIGN: Retrospective analysis of measurements from health visitor records made during routine child health surveillance at 6 weeks, 10 months, and 3 years of age. Multilevel analysis allowed for between-infant variation in fitted growth lines, and adjustment for other factors. Growth was described in terms of an intercept (z score at term) and growth slopes (change in z score per year) up to, and from, 4 months. SUBJECTS: 290 case babies delivered in Edinburgh hospitals to women who reported injection drug use by either themselves or their HIV infected partner, and 186 community controls. A total of 131 (45%) of the case babies were born to women who used drugs, predominantly opiates, during pregnancy and 93 (32%) to HIV infected women. The eight infected children were excluded from analysis. MAIN OUTCOME MEASURES: Age and sex standardised z scores for height, weight, and body mass index. RESULTS: 459 (96%) of the 476 records for cases and controls were traced, yielding 1432 weight and 939 height measurements. Maternal HIV infection was not found to affect growth; at 3 years the estimated effect on weight z score was 0.16 with 95% confidence interval (-0.25 to 0.57) and for height 0.18 (-0.19 to 0.55). Drug use during pregnancy was associated with lighter babies at 40 weeks followed by depressed growth in the first four months, these infants remaining just slightly smaller at 3 years with an estimated effect on z scores of -0.5 for weight with 95% confidence interval (-0.89 to -0.11) and -0.37 (-0.72 to -0.02) for height. CONCLUSIONS: Maternal HIV infection does not adversely affect growth in uninfected infants, and the effect of drug use during pregnancy is limited to small decrease in size at 3 years.