Viscosity and yield stress reduction in non-colloidal concentrated suspensions by surface modification with polymers and surfactants and/or nanoparticle addition.

A custom-designed apparatus termed the yield stress adaptor (YSA) has been used to evaluate the effect of polymer-surfactant coatings, and the addition of nanoparticles of different size, shape and surface chemistry, on the rheological properties of large hydrophilic particulates, sand, with the aim of reducing interparticle friction forces. Experimental results show that the flow properties of sand slurries at high volume fractions of sand (>50%) can be significantly enhanced by adding nanoparticles, and by surface modification with polymer/surfactant mixtures. A lesser effect is observed for polymer-only and surfactant-only coated samples. X-ray photoelectron spectroscopy was used to determine the concentration of organic species at the surface. The effect of polymer/surfactant concentration, adsorption time, polymer molecular weight, as well as surfactant charge and chemical structure were also addressed.

Cilia ultrastructure in children with Down syndrome.

Chronic sinusitis, otitis media with effusion, and upper respiratory tract infections are commonly found in patients with Down syndrome. These diseases are generally felt to be secondary to depressed immune function and altered craniofacial dimensions. Recently, a cilia ultrastructure abnormality was found in a child with Down syndrome. This study is the first to be carried out to determine if cilia ultrastructure abnormalities are prevalent in the population with Down syndrome. Four of 10 patients had documented cilia abnormalities, but these were present in the background of normal cilia, suggesting that they were the result rather than the cause of chronic sinusitis. Similarly, nasal epithelium metaplasia was detected in 50% of the patients. Chronic sinusitis, otitis media with effusion, and recurrent upper respiratory tract infections in children with Down syndrome cannot generally be attributed to primary cilia ultrastructure abnormalities.

Combination of ceftriaxone and acyclovir - an underestimated nephrotoxic potential?

Management of meningo-encephalitis often involves the need for antibiotic and antiviral treatment. We report a retrospective analysis over a 6-month period of 17 patients (age range 1-14 years) who were treated with combination therapy of ceftriaxone and acyclovir. Mean acyclovir and ceftriaxone doses were 1,222+/-304 and 2,315+/-509 mg/m(2) per day, respectively. Three patients developed acute renal failure with a peak creatinine of up to 865% above baseline, occurring 2-3 days after starting combination therapy. Patients revealed a tubular proteinuria pattern. Renal biopsy of 1 patient showed a tubulotoxic picture but no evidence of crystals. In 12 of 17 patients (70%) there was a significant increase in serum creatinine. This was significantly greater than literature reports of 16% with acyclovir monotherapy. The degree of renal impairment in our patients correlated significantly with the acyclovir dose, while no correlation was found with the ceftriaxone dose. We conclude that the addition of a second nephrotoxic drug aggravated the extent of renal injury in our patients. The mechanism is tubulotoxicity. Caution should be exercised when using this potentially nephrotoxic cocktail, with clear criteria established for the initiation of combination therapy and close monitoring of serum creatinine.

Optimal biopsy techniques in the diagnosis of primary ciliary dyskinesia.

OBJECTIVE: Adequate biopsy specimens that clearly demonstrate cilia, and therefore enable the determination of the presence or absence of primary cilia dyskinesia, may be difficult to obtain. This study is an attempt to identify the optimal sampling technique to best examine respiratory tract cilia. DESIGN: A prospective comparison of the four sampling techniques was carried out: nasal brushing, nasal biopsy, bronchial brushing, and tracheal biopsy. SETTING: Tertiary care pediatric hospital: Children's Hospital of Eastern Ontario. METHODS: Ten consecutive patients booked for bronchoscopy and tracheal biopsy underwent all four procedures. Specimens were examined under light microscopy for an assessment of quality. RESULTS: The nasal brushing and tracheal biopsy specimens provide superior quality (p = .22); however, nasal brushing is more cost efficient. Nasal biopsy samples frequently are metaplastic and therefore are inferior to nasal brushing samples (p = .02). CONCLUSION: With equal efficiency demonstrated, the reduction in potential morbidity and health care costs suggests nasal brushings to be the optimal initial investigation for primary ciliary dyskinesia.