Direct binding of respiratory syncytial virus to pneumococci: a phenomenon that enhances both pneumococcal adherence to human epithelial cells and pneumococcal invasiveness in a murine model

In a previous study we showed that pneumococcal adherence to epithelial cells was enhanced by a preceding respiratory syncytial virus (RSV) infection. RSV-glycoproteins, expressed on the infected cell surface, may play a role in this enhanced pneumococcal binding, by acting as bacterial receptors. In the current study, it was attempted to analyze the capacity of pneumococci to interact directly with RSV virions. By flow-cytometry, a direct interaction between RSV and pneumococci could be detected. Heparin, an inhibitor of RSV infectivity that interacts with RSV protein-G, blocked RSV-pneumococcal binding, indicating that the latter interaction is indeed mediated by protein-G. RSV-pneumococcal complexes showed enhanced adherence to uninfected human epithelial cells, compared with pneumococcal adherence without bound RSV, and this enhancement was also blocked by heparin. In addition, the significance of these findings in vitro was explored in vivo in a murine model. Both mice that were pretreated with RSV at day 4 before pneumococcal challenge and mice infected with both agents simultaneously showed significantly higher levels of bacteraemia than controls. Simultaneous infection with both agents enhanced the development of pneumococcal bacteraemia most strongly. It was hypothesized that direct viral binding is another mechanism by which RSV can induce enhanced pneumococcal binding to epithelial cells, a phenomenon that is translated in vivo by a higher invasiveness of pneumococci when administered simultaneously with RSV to mice. Apparently, RSV acts in this process as a direct coupling particle between bacteria and uninfected epithelial cells, thereby increasing colonization by and enhancing invasiveness of pneumococci.     

Implant design and interface force transfer. A photoelastic and strain-gauge analysis

Objectives: To compare stress and strain magnitudes of butt‐joint and internal‐cone oral implants in a bone simulant. Material and methods: Photoelastic and strain‐gauged models of solitary Brånemark^®, ITI^® and Astra Tech^® implants were obtained. Vertical and 20° oblique forces of 100 and 150 N were applied on the abutments in separate load cases. Isochromatic fringe patterns around implants were observed and photographed in the field of a polariscope. Strain‐gauge measurements were performed and principal strains induced around implants were calculated. Results: Isochromatic fringe orders of all designs were similar under both loading conditions (P>0.05). Strains around Brånemark^® implants were lower than around Astra Tech^® and ITI^® implants, particularly under vertical loads. The latter implants had similar strain magnitudes (P>0.05), although strains around the conical Astra Tech^® implant were lower under vertical load. Conclusions: Butt‐joint and internal‐cone oral implants have similar force distribution characteristics. The implant–abutment mating design is not a decisive factor affecting stress and strain magnitudes in a bone simulant.     

A randomized, masked study of triiodothyronine plus thyroxine administration in preterm infants less than 28 weeks of gestational age: hormonal and clinical effects

A randomized, placebo-controlled, masked study was conducted of the responses of thyroid parameters, cortisol, and the cardiovascular system to a single dose of triiodothyronine (T(3)) 24 h after birth, followed by a daily dose of thyroxine (T(4)) during 6 wk to infants <28 wk gestational age. Thirty-one infants were assigned to three groups: 1) group A: T(3) 24 h after birth plus daily T(4) during 6 wk; 2) group B: placebo T(3) and T(4) during 6 wk; and 3) group C: placebo T(3) and placebo T(4). T(4), free T(4), T(3), free T(3), reverse T(3), thyroid-stimulating hormone, and cortisol were measured in cord blood and on days 1, 3, 7, 14, 21, 42, and 56. Data on pulse rate, blood pressure, and cumulative dose of inotropic agents were collected. T(3) (0.5 microg/kg) resulted in a plasma increase until day 3. Thereafter, plasma T(3) levels were comparable between the groups. T(4), free T(4), and reverse T(3) were increased in groups A and B during the period of T(4) administration. Thyroid-stimulating hormone suppression was of shorter duration in group A. T(3) and T(4) administration did not have any effect on cortisol levels. We did not find any effects of T(3) or of T(4) administration on the cardiovascular system. A single injection of T(3) (0.5 microg/kg) given 22-26 h after birth only leads to a 2-d increase of T(3) levels and does not have effects on the cardiovascular system. This study does not support the use of T(3) according to our regimen in preterm infants.     

Pelvic floor spasms in children: an unknown condition responding well to pelvic floor therapy

OBJECTIVE: During a study period of 4 years, 21 children are seen for night time pelvic pain. These children typical wake up in the middle of the night with severe lower abdominal or perineal pain. During day some of them suffer urge syndrome. During urodynamic investigation extremely high pelvic floor activity as recorded by high urethral pressure was observed in these children. We therefore started pelvic floor relaxation biofeedback in these children. METHODS: All children diagnosed with pelvic floor spasms underwent biofeedback pelvic floor relaxation therapy in order to learn them to counteract pelvic pain due to these spasms. In those girls in whom detrusor hyperactivity was seen on urodynamics concomitant anticholinergic treatment was given (oxybutynin). RESULTS: Between January 1998 and January 2002 symptomatic pelvic floor spasms were diagnosed in 21 children (19 girls/2 boys). Pelvic floor relaxation biofeedback was successful for treatment of this condition in 17 of 21 children. Mean duration of therapy was 3 months (12 weekly sessions) and on long term follow-up relapse was seen in 3 of 17 successfully treated children. 10 of 17 successfully treated children received anticholinergics. CONCLUSION: Pelvic floor spasms in children (which can be secondary to detrusor overactivity) respond well to pelvic floor relaxation therapy.     

Rising prevalence of HIV-1 non-B subtypes in Belgium: 1983-2001

This study documented the HIV-1 subtype distribution in 2 Belgian hospitals and determined predictive demographics for non-B subtypes. Overall, subtype B was the most prevalent subtype in this population, followed by subtypes A and C. Several recombinants were detected, circulating recombinants as well as new ones. We found a rise in non-B subtypes from 0% in 1983 to 57% in 2001. The Cochran-Armitage trend test (P < 0.001) as well as the correlation analysis (R = 0.71, P = 0.0006) was highly significant. Recombinants were also increasing in this patient population from 0% in 1983 to 10% in 2001, with good support from the statistical analyses (trend test P < 0.001; correlation analysis R = 0.67, P = 0.0016). Heterosexual route of infection, black African race, African origin of the virus, and year of diagnosis were predictors for infection with non-B subtypes in multivariate analysis. This analysis indicates that the prevalence of non-B subtypes and recombinants in this patient population is high and increasing. Gathering demographic and sequence information from newly diagnosed patients could be useful to further follow the spread of non-B subtypes in Belgium and Europe, but subtyping based on sequence information still remains the most reliable method.     

Quantitative assessment of the transport of elastic and rigid vesicle components and a model drug from these vesicle formulations into human skin in vivo

The aim of this study was to quantitatively assess the distribution profiles of elastic and rigid vesicle material in human skin in vivo. Furthermore, the distribution profiles of the model drug ketorolac applied in these vesicle formulations was investigated. A deuterium-labelled phospholipid was incorporated into these vesicles to serve as a marker for the vesicle material. The vesicles were loaded with ketorolac at saturated concentrations. Vesicle solutions were applied non-occlusively onto the skin and the treated site was sequentially tape-stripped. Tape-strips were analyzed for vesicle material using attenuated total reflectance-Fourier transform infrared spectroscopy and for ketorolac by extraction of the tape-strips followed by high pressure liquid chromatography. Distribution profiles in the stratum corneum (SC) were obtained for the elastic and rigid vesicle material and for the ketorolac. These profiles have suggested that elastic vesicle material can rapidly enter the deeper layers of the SC and can reach almost the SC-viable epidermal junction. Rigid vesicle material, however, did not penetrate deep into the SC. Furthermore, the elastic vesicles were better than the rigid vesicles in the enhancement of ketorolac transport into human SC. The distribution profile of ketorolac in the deeper SC layers was, however, different from that of the vesicle material. This suggests that once the elastic vesicles partition into the SC, the ketorolac is released from the vesicles. The elastic vesicles are superior to the rigid vesicles both in terms of vesicular transport into the SC and in terms of therapeutic potential as a skin delivery vehicle.     

Invasive infection with Moraxella catarrhalis in two children with lymphatic leukemia and granulocytopenia

In two young children with leukaemia, a girl and a boy aged 5 and 4 years, respectively, an invasive infection due to Moraxella catarrhalis was diagnosed at the time of granulocytopenia. They were treated with antibiotics. The first child developed pneumonia and recovered, the other developed severe septic shock and died. M. catarrhalis is a Gram-negative diplococcus, frequently colonising the upper respiratory tract in young children. In childhood this pathogen mainly causes infections such as otitis media and sinusitis, while in adults it primarily causes laryngitis, bronchitis and pneumonia. Immunocompromised patients or patients with chronic cardiopulmonary disease have an increased risk of severe infections.     

Functional expression of the human thiazide-sensitive NaCl cotransporter in Madin-Darby canine kidney cells

The thiazide-sensitive Na(+)-Cl(-) cotransporter (NCC), which is expressed on the apical membrane of epithelial cells lining the distal convoluted tubule, is responsible for the reabsorption of 5% to 10% of filtered Na(+) and Cl(-). To date, functional studies on the structural and regulatory requirements for localized trafficking and ion-transporting activity of NCC have been hampered by lack of a suitable cell system expressing this cotransporter. Reported here is the functional expression of human NCC (hNCC) in a polarized mammalian cell of renal origin-that is, the high-resistance Madin-Darby canine kidney (MDCK) cell. Western blot testing revealed that the cells predominantly expressed the complex glycosylated (approximately 140 kD) form of hNCC. hNCC was present primarily in the apical part of the cell. The functionality of hNCC was demonstrated by the gain of thiazide-sensitive Na(+) uptake and transepithelial transport activity. Na(+) uptake was significantly increased after short-term (15 min) treatment with forskolin, whereas cyclic guanosine monophosphate, wortmannin, phorbol 12-myriatate 13-acetate, and staurosporine were without effect. This indicates that hNCC activity is regulated through cyclic adenosine monophosphate, rather than via cyclic guanosine monophosphate, phospho-inositide 3-kinases or protein kinase C. Aldosterone did not alter Na(+) uptake in the short term (15 min) but significantly increased the transport activity in the long term (16 h). The latter effect of aldosterone was due to an effect on the cytomegalovirus promoter/enhancer driving the expression of hNCC. hNCC-MDCK cells are a good model for the study of the regulation of apical trafficking and ion-transporting activity of hNCC.