A novel bacterial l-arginine sensor controlling c-di-GMP levels in Pseudomonas aeruginosa.

Nutrients such as amino acids play key roles in shaping the metabolism of microorganisms in natural environments and in host-pathogen interactions. Beyond taking part to cellular metabolism and to protein synthesis, amino acids are also signaling molecules able to influence group behavior in microorganisms, such as biofilm formation. This lifestyle switch involves complex metabolic reprogramming controlled by local variation of the second messenger 3', 5'-cyclic diguanylic acid (c-di-GMP). The intracellular levels of this dinucleotide are finely tuned by the opposite activity of dedicated diguanylate cyclases (GGDEF signature) and phosphodiesterases (EAL and HD-GYP signatures), which are usually allosterically controlled by a plethora of environmental and metabolic clues. Among the genes putatively involved in controlling c-di-GMP levels in P. aeruginosa, we found that the multidomain transmembrane protein PA0575, bearing the tandem signature GGDEF-EAL, is an l-arginine sensor able to hydrolyse c-di-GMP. Here, we investigate the basis of arginine recognition by integrating bioinformatics, molecular biophysics and microbiology. Although the role of nutrients such as l-arginine in controlling the cellular fate in P. aeruginosa (including biofilm, pathogenicity and virulence) is already well established, we identified the first l-arginine sensor able to link environment sensing, c-di-GMP signaling and biofilm formation in this bacterium.

Stability of anterior open bite treatment with bonded spurs associated with high-pull chincup.

OBJECTIVE: To evaluate the stability of anterior open bite (AOB) treatment with bonded spurs associated with high-pull chincup (BS/HPCC). METHODS: The experimental group consisted of 25 Class I AOB patients (15 female, 10 male) treated with BS/HPCC for 1 year. Cephalograms were analysed at pre-treatment (T1), post-treatment (T2) and at the 3-year post-treatment (T3) stage with the patients mean ages of 8.10, 9.14 and 12.18 years, respectively. The control group consisted of 23 subjects (13 female, 10 male) with normal occlusion, with comparable ages at the 3 stages (8.45, 9.45 and 12.50 years at T1, T2 and T3, respectively). T tests were used for intergroup comparisons at T1 and to compare the changes during the 3-year post-treatment period (T2-T3). Intragroup comparison in the treated group was evaluated with dependent t tests between T1 and T2. Correlations between the overbite changes in the T2-T3 period, the pre-treatment AOB severity and the amount of correction achieved during treatment were evaluated with Pearson's correlation coefficient. RESULTS: No statistically significant relapse of the AOB was found at T3. Only 1 patient had a clinically significant AOB relapse. Neither the pre-treatment AOB severity nor the amount of correction was related to overbite changes during the 3-year post-treatment period. CONCLUSIONS: There was no statistically significant relapse of the AOB, and the clinical stability of AOB correction 3-year post-treatment was of 96%.

Cephalometric evaluation of Class II malocclusion treatment with cervical headgear and mandibular fixed appliances.

The present study aimed to evaluate the cephalometric changes in Class II patients treated exclusively with cervical headgear (CHG) in the maxillary arch and fixed appliances in the mandibular arch as compared with a control group. The sample comprised 82 lateral cephalograms obtained pre- (T1) and post- (T2) treatment/observation of 41 subjects, divided into two groups: group 1-25 Class II division 1 patients (20 females and five males), with a mean pre-treatment age of 10.4 years, treated for a mean period of 2.5 years and group 2-16 Class II untreated subjects (12 females and four males), with a mean initial age of 9.9 years, followed for a mean period of 2.2 years. Treatment changes between the groups were compared by means of t-tests. The results showed restriction of maxillary forward displacement and also a restriction in maxillary length growth, improvement in the maxillomandibular relationship, restriction of mandibular incisor vertical development, reduction in overjet and overbite, and improvement in molar relationship. It was concluded that this treatment protocol corrected the Class II malocclusion characteristics primarily through maxillary forward growth restriction.

Characteristics of antibiotic-resistant Escherichia coli in the rectum of healthy school-children.

During a 3-year period, 771 rectal swabs were taken from abacteriuric school-children. Out of 709 E. coli strains, each isolated from one faecal specimen, 102 were found to be resistant to one or more antibacterial agents, and 607 to be fully sensitive. Another 204 resistant strains were found by selection for antibiotic resistance. The antibiotic-sensitive and the resistant strains were found to be two somewhat different populations, distinguished by a different distribution of O antigen types. Also, the K1 antigen was more common among the sensitive than among the resistant strains. Resistant strains that were not O typable were very seldom haemolytic.

Outbreak of respiratory illness on board a ship cruising to ports in southern Europe and northern Africa.

A large outbreak of influenza-like and diarrhoeal illness took place over a period of 21 days in April 1984 on board a ship cruising to ports in southern Europe and northern Africa. A cohort study of the 418 passengers was made by postal questionnaire and personal interview. Of the 391 passengers who were interviewed or who returned a questionnaire, 335 (86%) were affected. Of the ill passengers, 295 (88%) had an influenza-like illness. These included 20 with signs of lower respiratory tract infection. In 24 passengers, a viral infection was diagnosed. Influenza B virus infection was identified in 14 cases; other diagnoses were influenza A, para-influenza, respiratory syncytial virus and Epstein-Barr virus infections. In two of the 81 patients tested for Legionella antibodies, a titre of 128 was found; in 16 and 44 patients, titres of 64 and 32 respectively. The outbreak was thus evidently caused by multiple pathogens mainly affecting the respiratory tract. Although most of the passengers acquired their infections on board the ship, a common source was not discovered. A steep rise in the epidemic curve the day after the air-conditioning was switched on, however, is worth noting. If and when similar instances of the 'Sick Boat Syndrome' recur, a search for environmental sources of infection is to be recommended.

Pregnancies in women with and without renal scarring after urinary infections in childhood.

OBJECTIVE: To compare the outcome of pregnancy in women with and without renal scarring after childhood urinary infections with that in unmatched controls. DESIGN: Retrospective study of pregnancies in women prospectively followed up from their first recognised urinary infection. SETTING: Tertiary referral centre in Gothenburg. SUBJECTS: 111 Women attending an outpatient clinic for women with urinary infection during 1975-83, of whom 41 (65 pregnancies) were studied (19 women with renal scarring (32), 22 without scarring (33)), and 65 controls (65) randomly selected and matched for parity, age, smoking habits, and date of delivery. MAIN OUTCOME MEASURES: Urinary infections and complications in pregnancy. RESULTS: The incidence of bacteriuria during first pregnancies was significantly greater in women with (9, 47%) and without (6, 27%) renal scarring after childhood urinary infection than in controls (1, 2%) (p less than 0.001, 0.01 respectively). Symptomatic infections were seen only among women with a history of urinary infection: four women with renal scarring (three of whom had vesicoureteric reflux) developed pyelonephritis and three cystitis, and one woman without scarring developed pyelonephritis. Mean blood pressure was higher among women with severe renal scarring than controls (4/11 v 3/44; p less than 0.05) before and during pregnancy. There was no significant difference in the incidence of pre-eclampsia, operative delivery, prematurity, or birth weight. CONCLUSIONS: Women with a history of previous urinary infections had a high incidence of bacteriuria during pregnancy, and those with renal scarring and persistent reflux were prone to develop acute pyelonephritis. The risk of serious complications in pregnancy, however, was not increased in women with severe renal scarring, possibly owing to their continuous clinical supervision.

[The year of the world aids day: children in a world of AIDS]. / Arets världsaidsdag: barn i en värld med aids.

PIP: "Children living in a world with AIDS" was the theme of a UNAIDS campaign launched because 1 million children are infected with HIV and 9 million children have become orphans due to AIDS (90% in sub-Saharan Africa). During 1996 alone, 400,000 children were infected: 90% were infected during pregnancy, delivery, or while breast feeding; the remaining 10% were infected sexually or via blood or blood products. In Africa, only one-third of HIV-infected children survive their 3rd birthday, and 8% of all children in Zimbabwe have lost their mothers to AIDS. A similar situation is rapidly evolving in Asia and South America. In Spain and Italy, more than 600 children have AIDS; most of them were infected through drug-abusing mothers. In France the figure is comparable, but here a large segment is represented by children of mothers from African countries. The total number of children with AIDS in the European Community is 2800: 86% were infected through their mothers. Romania has 4000 children with AIDS, who were predominantly infected via nonsterile syringes and blood transfusion. The European Commission has a specific AIDS prevention program, which addresses the measurement of disease spread, counteracting the disease, information and education, support for persons with HIV/AIDS, and countering discrimination. The risk of mother-to-child HIV transmission can be reduced from 25% to 8% by zidovudine (AZT) treatment during pregnancy and delivery.^ieng

Influence of miniscrew dental root proximity on its degree of late stability.

Purpose of this study was to evaluate the influence of miniscrew dental root proximity on its late stability degree. 40 miniscrews were inserted between maxillary second premolars and first molars for anterior retraction. Post-surgical radiographs were used to measure the septum width in the insertion site, insertion height, distal and mesial distance from miniscrew to dental root, and the smallest distance between miniscrew and dental root. The miniscrews were divided in two groups according to septum width: ≤3 mm (20 miniscrews) and >3 mm (20 miniscrews). The soft tissue in the insertion site, sensitivity during load, plaque around the miniscrew, and evaluation period were also considered. The results showed no significant difference in miniscrew mobility degree and success rate between groups. Miniscrew dental root proximity did not influence the stability and success rate when the distance between the miniscrew and dental root indicated no periodontal ligament invasion. The overall success rate was 90% and no variable was associated with miniscrew failure. Nevertheless, patient sensitivity was frequently associated with some degree of mini-implant mobility. The septum width did not influence the stability and success rate of this anchorage system, but the extreme root proximity did.

Mini-implant insertion based on tooth crown references: a guide-free technique.

Mini-implant insertion requires accurate surgical technique. This study shows an insertion technique using only tooth crown references; its scientific basis is evaluated radiographically. The sample consisted of 213 inter-radicular septa, evaluated in 53 bitewing radiographs. The proximal contour of adjacent tooth crowns was used to define septum width. The midpoint of the septum width was linked to the interdental contact point to determine septum midline. The distances from septum midline to mesial and distal teeth were measured to evaluate the septum midline centralization degree in two different septum heights. The difference between mesial and distal distances represented the septum midline deviation degree. The mesial and distal distances were compared by t-tests, and the septum midline deviation was correlated with septum height using Pearson's correlation test. The mesial and distal distances were not statistically different in the midpoint of the septum height, but they were different at the apical septum height. There was a moderate correlation (r=0.45) between septum midline deviation and septum height. The tooth crown references evaluated on interproximal radiographs determine a high centralization degree of the septum midline on which the insertion site could be defined. The greater centralization degree was observed at the coronal septum area.