Fracture repair during external fixation: Torsion tests of rabbit osteotomies

Bone repair was studied in the rabbit tibiofibular bone after a midshaft transverse osteotomy stabilized by external fixation and heavy compression. Both subendosteal and subperiosteal callus formation with concomitant contact healing were observed within 3 weeks, and were further succeeded by subendosteal resorption and increased porosis resulting in atrophy of the cortical bone. Subjected to the torsion test, the bones exhibited restoration of strength within 3 weeks, with maximal energy absorption and elasticity at 6 weeks. The failure of the osteotomy in the torsion test, with radiographic visibility of the osteotomy, characterized the soft-tissue type of behavior of the bones. Hard-tissue like behaviour of the bones with resistance to torsion at the osteotomy site and radiographic obliteration of the osteotomy line occurred by 12 weeks, indicating complete union of the osteotomy. Our experiments demonstrate that elastic external fixation is preferable to the rigid compression plate.     

Uhthoff's symptom in multiple sclerosis

A case report is presented in which a patient's initial complaint is of blurred vision after exercise (Uhthoffs symptom). Visual acuity and colour vision were found to be reduced after exercise. Additional neurological signs included homonymous scotomata and delayed visual evoked and somatosensory responses. Magnetic resonance imaging demonstrated multiple abnormal lesions in the brain. The significance of this symptom and its relationship to multiple sclerosis are discussed.     

Treatment of ptosis in chronic progressive external ophthalmoplegia.

Seventeen patients with ptosis as a feature of chronic progressive external ophthalmoplegia were managed in accordance with a new protocol. An anterior approach levator advancement was performed on seven patients (13 lids) with more than 4 mm of levator function and a brow suspension procedure on eight patients (14 lids) with minimal levator function, in whom the frontalis muscle was relatively spared. Ptosis props were prescribed for two patients with a very weak orbicularis and poor lid closure. Six patients required long term lubricants, and one developed a postoperative corneal abscess associated with a poor Bell's phenomenon. Satisfactory elevation of the lids was achieved in 16 patients (25 lids).     

Prevention of prematurity: Haguenau perinatal survey, 1971-1985

A preterm birth prevention program was instituted in France in the early 1970s. Its effectiveness has been assessed through a perinatal study in Haguenau. A relationship between prenatal care improvement and preterm birth rate decrease was noted, but a causal interpretation cannot be derived from such an observational study. However, some arguments do support this interpretation: no satisfactory alternative explanation (such as biases in pregnancy duration measurement, change in the composition of the population of pregnant women, or secular trend), a plausible causal pattern, and a dose-response relationship between prenatal care and preterm birth rate. The Haguenau study results can be applied to other French regions, but extrapolation to other countries would depend on their social, medical and cultural contexts.     

Increased GABAergic transmission aggravates nucleus basalis magnocellularis lesion-induced behavioral deficits

Quisqualic acid NBM lesions had no effect on water maze performance, but slightly impaired passive avoidance acquisition. GammavinylGABA treatment alone had no effect on the passive avoidance and water maze performance, but aggravated acquisition deficit in rats subjected to NBM lesioning. However, gammavinylGABA-treated NBM-lesioned rats reached control level of performance.     

Effect of surface conditioning methods on the bond strength of luting cement to ceramics

OBJECTIVES: This study evaluated the effect of three different surface conditioning methods on the bond strength of a Bis-GMA based luting cement to six commercial dental ceramics. METHODS: Six disc shaped ceramic specimens (glass ceramics, glass infiltrated alumina, glass infiltrated zirconium dioxide reinforced alumina) were used for each test group yielding a total number of 216 specimens. The specimens in each group were randomly assigned to one of the each following treatment conditions: (1) hydrofluoric acid etching, (2) airborne particle abrasion, (3) tribochemical silica coating. The resin composite luting cement was bonded to the conditioned and silanized ceramics using polyethylene molds. All specimens were tested at dry and thermocycled (6.000, 5-55 degrees C, 30 s) conditions. The shear bond strength of luting cement to ceramics was measured in a universal testing machine (1 mm/min). RESULTS: In dry conditions, acid etched glass ceramics exhibited significantly higher results (26.4-29.4 MPa) than those of glass infiltrated alumina ceramics (5.3-18.1 MPa) or zirconium dioxide (8.1 MPa) (ANOVA, P<0.001). Silica coating with silanization increased the bond strength significantly for high-alumina ceramics (8.5-21.8 MPa) and glass infiltrated zirconium dioxide ceramic (17.4 MPa) compared to that of airborne particle abrasion (ANOVA, P<0.001). Thermocycling decreased the bond strengths significantly after all of the conditioning methods tested. SIGNIFICANCE: Bond strengths of the luting cement tested on the dental ceramics following surface conditioning methods varied in accordance with the ceramic types. Hydrofluoric acid gel was effective mostly on the ceramics having glassy matrix in their structures. Roughening the ceramic surfaces with air particle abrasion provided higher bond strengths for high-alumina ceramics and the values increased more significantly after silica coating/silanization.     

Retinal topography in reef teleosts. II. Some species with prominent horizontal streaks and high-density areae

The retinal ganglion cell layer of five species of reef teleosts was studied from Nissl-stained whole-mounts and the distribution of neural elements determined quantitatively. Iso-density contour maps of neurons in the ganglion cell layer revealed a temporal area centralis (ranging from 3.5 to 8.3 x 10(4) cells/mm2) which often extended into a horizontal streak (ranging from 1.4 to 5.0 x 10(4) cells/mm2) across the retinal meridian. Species possessing a marked horizontal streak were found to inhabit open water and perceive their environment with an uninterrupted view of sand-water horizon. The behavioural significance of these horizontal areas of acute vision is also discussed.