Construction,quality assurance and calibration of spherical isotropic fibre optic light diffusers

Spherical isotropic fibre optic light diffusers are used in photodynamic therapy either as a light source or as a light detector. The construction of light diffusers using different materials is described, viz. an optical method involving local polymerization of a dental fissure sealant, which is referred to as the Henderson method, and a second method using plastic or ceramic pre-fabricated spheres. Quality tests necessary for reliable clinical use are presented for the mechanical strength, output power and isotropy. The maximum pull-off force and blow-off output power for the different kinds of diffusers were determined. The calibration procedures are given for measurement of the output power and wavelength of the light emitted by a diffuser and for measurement of the fluence rate by a light-detecting diffuser, using a compact integrating sphere device. With all types of diffusers described, an isotropy can be obtained of better than ± 20% measured over a 320° angle for spheres as small as 1 mm. Larger ceramic diffusers are particularly suitable for delivering high output powers. A 3-mm-diameter ceramic diffuser mounted on a 600-m-core fibre can emit up to 5 W of continuous wave (CW) visible light in air. Diffusers used for light detection can measure the light fluence rate in tissue with 15% accuracy or better if calibration factors are determined for each individual probe.     

The influence of dairy products on plasma uric acid in women

Elevated levels of plasma uric acid have been linked to increased risk of cardiovascular diseases and their complications. As dairy proteins have been found to decrease plasma uric acid without increasing glomerular filtration rate, a sample of postmenopausal women living in Montreal was studied to investigate the nature of this relationship. Participants (158 Roman Catholic nuns) were randomly assigned to one of two test diets for a period of four weeks: the dairy foods group (n=81) consumed approximately 30 grams of dairy protein daily and the dairy-free diet group (n=77) ate no dairy foods at all. Subjects completed two one-day food records, a core questionnaire and a dairy foods diet history; blood specimens were obtained, and blood pressure, height and weight were measured. Average nutrient intakes differed as a consequence of the test diets, with significantly greater intakes of protein, fat, saturated fat, monounsaturated fat, potassium and calcium (p<0.01) in the dairy group after the study period, and lower dietary levels of protein, cholesterol, calcium and retinol (p<0.01) in the dairy-free group. Plasma uric acid was unchanged after the dietary intervention in the dairy group, but increased by 7.8 µmol/1 (p=0.03) in subjects on the dairy-free diet; however, diastolic blood pressure decreased in response to calcium (=–22.9, SE=10.0,p=0.02) among those whose diet included dairy foods. The study results suggest that proteins of dairy origin may play a role in stabilising or lowering plasma uric acid, and that calcium or other components found in milk products may also reduce diastolic blood pressure. While these findings have implications for dietary prevention to decrease cardiovascular risk in postmenopausal women, further investigations should examine these mechanisms in men over the age of 50 to ascertain whether a similar response would occur.     

Results of flexor-to-extensor and extensor brevis tendon transfer for correction of the crossover second toe deformity

Between 1990 and 1995, 38 patients (42 feet) underwent repair for crossover toe deformity, 31 (35 feet) of whom returned for final examination at an average of 51.6 months (range, 24-81 months). Causes included trauma, iatrogenic, and unknown. Presenting complaints included dorsal pain with either metatarsalgia or joint pain, isolated metatarsophalangeal (MP) joint pain, metatarsalgia, painful plantar callus, metatarsalgia and joint pain, and painful dorsal callus. All patients were treated with one of two operative techniques, either the flexor-to-extensor tendon transfer or the extensor brevis tendon transfer. Choice of procedure depended on the stage of preoperative deformity. Twenty-four patients were completely satisfied with the surgical correction, 6 were satisfied with reservations, and 1 was dissatisfied. The average postoperative AOFAS score for all patients was 85 points (range, 54-100 points), which correlated strongly with patient satisfaction. Twenty-two patients stated that they had no postoperative pain, 8 reported some pain, and 1 had frequent pain at the corrected toe. In 30 feet, there was no recurrence; three patients had mild residual crossover toe deformity, and two patients had recurrent deformity, although all MP joints were stable. Follow-up radiographs demonstrated substantial reduction in MP joint angles in both the AP (from 7 degrees to -1 degree) and lateral (from 45 degrees to 25 degrees) projections. This article reviews the surgical technique of both procedures, proposes specific indications for each, and presents outcomes. Based on our findings, the extensor brevis tendon transfer is appropriate for stage 1, stage 2, and flexible stage 3 deformities. Flexor-to-extensor tendon transfer is appropriate for rigid stage 3 and stage 4 deformities and for all patients with a symptomatic neuroma of the second web space (where the extensor brevis transfer is not possible). Stiffness of the MP joint is a potential problem with the flexor-to-extensor tendon transfer.     

Nitric Oxide and -Arginine Cause an Accumulation of Utrophin at the Sarcolemma: A Possible Compensation for Dystrophin Loss in Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD), a severe X-linked recessive disorder which results in progressive muscle degeneration, is due to a lack of dystrophin, a membrane cytoskeletal protein. An approach to treatment is to compensate for dystrophin loss with utrophin, another cytoskeletal protein with over 80% homology with dystrophin. Utrophin is expressed, at the neuromuscular junction, in normal and DMD muscles and there is evidence that it may perform the same cellular functions as dystrophin. So, the identification of molecules or drugs that could up-regulate utrophin is a very important goal for therapy. We show that in adult normal and mdx mice (an animal model of Duchenne myopathy) treated with -arginine, the substrate of nitric oxide synthase (NOS), a pool of utrophin localized at the membrane appeared and increased, respectively. In normal and mdx myotubes in culture, -arginine, nitric oxide (NO), or hydroxyurea increased utrophin levels and enhanced its membrane localization. This effect did not occur with -arginine, showing the involvement of NOS in this process. The NO-induced increase in utrophin was prevented by oxadiazolo-quinoxalin-1-one, an inhibitor of a soluble guanylate cyclase implicated in NO effects. These results open the way to a potential treatment for Duchenne and Becker dystrophies.     

The prevention of periprosthetic fractures in total hip and knee arthroplasty

Periprosthetic fractures in total hip and total knee arthroplasty lead to considerable morbidity in terms of component fixation, bone loss, and subsequent function. The management of these fractures is technically demanding and may result in suboptimal fixation owing to poor bone stock. The prevention, early recognition, and appropriate management of such fractures are therefore critical. The pathogenesis of periprosthetic factors is multifactorial. There are a number of intrinsic patient influences such as bone stock, biomechanics, and compliance. There are also a host of extrinsic factors over which the surgeon has more control. The prevention of periprosthetic fractures requires careful preoperative planning and templating, the availability of the necessary expertise and equipment, and knowledge of the potential pitfalls so that these can be avoided both intraoperatively and in follow-up.     

Some puzzles in the microscopic structure of the stroma

The mammalian corneal stroma has some intriguing features related to its lamellar structure. OPTICAL LAMINATION: Stromal sections under the polarizing microscope show birefringent bands that are about 5 times less numerous than the collagenous lamellae seen in transmission electron microscopy (TEM). Scattered light reveals similar laminae in the intact fresh tissue. COHESION: Very thin sections of stroma do not fall apart under water, indicating the presence of a structural framework that holds the collagen fibrils together. SHEAR DISTORTION: The stroma shears very readily in its plane; the shear amplitude increases and then decreases as the tissue hydrates. This suggests that the structural framework is coiled at physiological hydration and can expand about 10 times. FOLDING: When the stroma swells, the lamellae are thrown into waves that lie both in the plane of and perpendicular to its surface. It is difficult to understand how the latter are packed.     

Induction of eotaxin expression and release from human airway smooth muscle cells by IL-1beta and TNFalpha: effects of IL-10 and corticosteroids.

Eotaxin is a novel C-C chemokine with selective chemoattractant activity for eosinophils. We determined whether eotaxin could be produced by human airway smooth muscle (HASM) cells in culture and examined its regulation by interleukin-10 (IL-10) and the corticosteroid, dexamethasone. Stimulation of the cells with interleukin-1beta (IL-1beta) or tumour necrosis factor (TNFalpha) each at 10 ng ml(-1) induced the release of eotaxin protein with maximal accumulation by 24 h. Interferon-gamma (IFNgamma) alone at 10 ng ml(-1) had no effect and there was no synergy between these cytokines on the release of eotaxin. Reverse phase high performance liquid chromatographic (HPLC) analysis of supernatents from cells treated with TNFalpha (10 ng ml(-1) for 96 h showed immunoreactivity to eotaxin which eluted with the expected retention time of 34.5-35 min. Both IL-1beta and TNFalpha-induced release of eotaxin was not inhibited by dexamethasone (1 microM), however IL-10 (10 ng ml(-1)) had a significant inhibitory effect. Dexamethasone and IL-10 did not inhibit the induction of eotaxin mRNA induced by IL-1beta or TNFalpha. Thus, human airway smooth muscle cells can release eotaxin and could be an important source of chemokine production during airway inflammatory events.     

ABO genotyping-identification of O1, O1*, and O2 alleles using the polymerase chain reaction-sequence specific oligonucleotide (PCR-SSO) technique

ABO polymorphism at the gene level has been investigated by molecular methods, predominantly sequencing and restriction fragment length polymorphism (RFLP). We describe the application of the polymerase chain reaction-sequence specific oligonucleotide (PCRSSO) method, which is considered to be more versatile for large sample numbers, compared with conventional ABO genotyping by PCR-RFLP. PCR-SSO, while maintaining accurate and reliable results, reduces costs and labor. A population of 155 random individuals was investigated for the three O alleles, O1, O1*, and O2. The allelic frequencies were 35 percent, 26 percent, and 5 percent, respectively. PCR-SSO results correlated completely with both serologic and PCRRFLP results.     

Double keystone bird in a keystone species complex

Species in a Colorado subalpine ecosystem show subtle interdependences. Red-naped sapsuckers play two distinct keystone roles. They excavate nest cavities in fungus-infected aspens that are required as nest sites by two species of swallows, and they drill sap wells into willows that provide abundant nourishment for themselves, hummingbirds, orange-crowned warblers, chipmunks, and an array of other sap robbers. The swallows thus depend on, and the sap robbers benefit from, a keystone species complex comprised of sapsuckers, willows, aspens, and a heartwood fungus. Disappearance of any element of the complex could cause an unanticipated unraveling of the community.