Healing bone using recombinant human bone morphogenetic protein 2 and copolymer

Middiaphyseal 2.5-cm segmental defects in the right femurs of 12 sheep were stabilized with stainless steel plates and implanted with (1) 2 mg recombinant human bone morphogenetic protein 2 and poly[D,L-(lactide-co-glycolide)] bioerodible polymer with autologous blood (n = 7), (2) 4 mg recombinant human bone morphogenetic protein 2 and poly[D,L-(lactide-co-glycolide)] and blood (n = 3), or (3) poly[D,L-(lactide-co-glycolide)] and blood only (n = 2). Bone healing was evaluated for 1 year using clinical, radiographic, gross pathologic, and histologic techniques. Union occurred in three sheep in Group 1, two in Group 2, and none in Group 3. In the animals that healed, new bone first was visible radiographically between Weeks 2 and 6 after implantation; new bone mineral content equaled that of the intact femur not surgically treated by Week 16; recanalization of the medullary cavity approached completion at Week 52; and at necropsy the surgical treated femurs were rigidly healed, the poly[D,L-(lactide-co-glycolide)] was resorbed completely, and woven and lamellar bone bridged the defect site. In two Group 1 sheep euthanized at Weeks 2 and 6, polymer particles were permeated by occasional multinucleated giant cells. Some plasma cells, lymphocytes, and neutrophils were present locally. The poly[D,L-(lactide-co-glycolide)] tended to fragment during surgical implantation. Despite these observations, the recombinant human bone morphogenetic protein 2/poly[D,L-(lactide-co-glycolide)] implant was able to heal large segmental bone defects in this demanding model.     

A pilot study of the marginal adaptation and surface morphology of glass-cermet cements

This study investigated changes in the marginal adaptation and surface morphology of Ketac-Silver and Chelon-Silver glass-current cements over time. Dispersalloy amalgam was used as a control. Contralateral pairs of carious primary molars were restored with the test materials and amalgam. Clinical evaluations were scheduled at 12, 18, and 24 months after placement. Gold-plated replicas of the restorations were observed with scanning electron microscopy. Fractures and cracks in the surface of the Dispersalloy and Chelon-Silver increased the surface roughness; however, the damage was superficial and self-limiting in the Dispersalloy restorations, while in Chelon-Silver the fractures caused the material to break down in layers. A substantial quantity of pores, usually smaller than 50 microns in diameter, were observed throughout the surface of the Chelon-Silver restorations. The pores in the surface of Ketac-Silver were fewer and smaller. The incidence of cavomarginal breakdown increased with time. Chelon-Silver restorations had a higher rate of cavomarginal breakdown than did Ketac-Silver and Dispersalloy restorations up to 18 months. However, there was no statistically significant difference in the marginal adaptation of the three groups at 24 months.     

Eosinophilic foreign body granuloma after multiple self-administered bee stings

A bee sting can cause a foreign body granuloma of the skin, due to activated macrophages at the stinging site. A 52-year-old woman presented with a large doughnut-shaped ulcerative tumour on the left side of her face. A bean-sized facial papule had grown to a 4.0 x 3.9 x 1.1 cm mass after multiple bee stings induced by herself over a period of 1 year. Histology showed epidermal ulceration with granulomatous inflammatory cell infiltration of many eosinophils. No micro-organisms or foreign bodies were identified. Intralesional triamcinolone acetonide was not effective, but an excellent outcome was obtained using carbon dioxide laser vaporization of the lesion.     

Amyloid precursor protein mRNA stability is controlled by a 29-base element in the 3'-untranslated region

In the accompanying paper (Zaidi, S. H. E., Denman, R., and Malter, J. S. (1994) J. Biol. Chem. 269, 24000-24006) we demonstrate that in tumor and normal cells, multiple cytosolic proteins interact with a 29-base sequence in the 3'-untranslated region of amyloid precursor protein (APP) mRNA. These data suggested that APP gene expression may be modulated by regulated APP mRNA decay. We have investigated this prediction by measuring the decay rates of APP mRNA in resting and mitogen-treated peripheral blood mononuclear cells and H4 and K562 tumor cell lines. In resting peripheral blood mononuclear cells, APP mRNA decayed with a half-life of 4 h. Under these conditions, the activity of APP mRNA-binding proteins was not detectable. After activation, binding protein activities were induced, and APP mRNA decay was blocked with a half-life of > 12 h. In log phase neuronal or lymphoid tumor cell lines, binding activity was constitutively present and APP mRNA displayed a half-life of > 12 h. Protein synthesis inhibition by cycloheximide had no effect on APP mRNA decay in normal or tumor cells. Transfected wild type or mutant APP mRNAs that lacked the 29-base region were stable (t1/2 > 10 h) in K562 tumor cells. Therefore, we conclude that the 29-base region functions in cis to destabilize APP mRNA in resting, normal cells. Upon activation APP mRNA-binding proteins are induced, interact with the 29-base region, and likely participate in stabilization of the mRNA.     

Photorefractive keratectomy for astigmatism greater than -2.00 diopters in eyes with low, high, or extreme myopia

PURPOSE: To assess the efficacy of excimer laser photorefractive astigmatic keratectomy (PARK) in correcting astigmatism of more than -2.00 diopters (D) in eyes with low, high, and extreme myopia. SETTING: Pusan National University Hospital, Pusan, Korea. METHODS: Eighty-five patients (110 eyes) whose spherical error ranged from -3.00 to -13.00 D and cylinder ranged from -2.00 to -5.50 D had PARK with a VISX Twenty-Twenty excimer laser; follow-up was 6 months. All cases of myopic astigmatism were treated using the elliptical method and multizone ablation technique. Eyes were divided into 3 groups: low myopia, less than 6.00 D (n = 47); high myopia, from 6.25 to 10.00 D (n = 43); extreme myopia, over 10.25 D (n = 20). Alpins vector analysis was used to calculate the astigmatic change. RESULTS: By vector analysis, the success rate of astigmatic correction was more predictable in the low and high myopia groups than in the extreme myopia group (P < .05). There was little improvement in astigmatism in the extreme myopia group. CONCLUSION: Using PARK to correct astigmatism greater than -2.00 D in eyes with myopia less than -10.00 D tended to result in undercorrection; astigmatic correction in eyes with myopia over 10.25 D was minimal.     

Linker histone tails and N-tails of histone H3 are redundant: scanning force microscopy studies of reconstituted fibers

The mechanisms responsible for organizing linear arrays of nucleosomes into the three-dimensional structure of chromatin are still largely unknown. In a companion paper (Leuba, S. H., et al. 1998. Biophys. J. 74:2823-2829), we study the contributions of linker histone domains and the N-terminal tail of core histone H3 to extended chromatin fiber structure by scanning force microscopy imaging of mildly trypsinized fibers. Here we complement and extend these studies by scanning force microscopy imaging of selectively reconstituted chromatin fibers, which differ in subtle but distinctive ways in their histone composition. We demonstrate an absolute requirement for the globular domain of the linker histones and a structural redundancy of the tails of linker histones and of histone H3 in determining conformational stability.