Effects of estrogen on growth plate senescence and epiphyseal fusion

Estrogen is critical for epiphyseal fusion in both young men and women. In this study, we explored the cellular mechanisms by which estrogen causes this phenomenon. Juvenile ovariectomized female rabbits received either 70 μg/kg estradiol cypionate or vehicle i.m. once a week. Growth plates from the proximal tibia, distal tibia, and distal femur were analyzed after 2, 4, 6, or 8 weeks of treatment. In vehicle-treated animals, there was a gradual senescent decline in tibial growth rate, rate of chondrocyte proliferation, growth plate height, number of proliferative chondrocytes, number of hypertrophic chondrocytes, size of terminal hypertrophic chondrocytes, and column density. Estrogen treatment accelerated the senescent decline in all of these parameters. In senescent growth plates, epiphyseal fusion was observed to be an abrupt event in which all remaining chondrocytes were rapidly replaced by bone elements. Fusion occurred when the rate of chondrocyte proliferation approached zero. Estrogen caused this proliferative exhaustion and fusion to occur earlier. Our data suggest that (i) epiphyseal fusion is triggered when the proliferative potential of growth plate chondrocytes is exhausted; and (ii) estrogen does not induce growth plate ossification directly; instead, estrogen accelerates the programmed senescence of the growth plate, thus causing earlier proliferative exhaustion and consequently earlier fusion.

Control of somite patterning by signals from the lateral plate.

The body musculature of higher vertebrates is composed of the epaxial muscles, associated with the vertebral column, and of the hypaxial muscles of the limbs and ventro-lateral body wall. Both sets of muscles arise from different cell populations within the dermomyotomal component of the somite. Myogenesis first occurs in the medial somitic cells that will form the epaxial muscles and starts with a significant delay in cells derived from the lateral somitic moiety that migrate to yield the hypaxial muscles. The newly formed somite is mostly composed of unspecified cells, and the determination of somitic compartments toward specific lineages is controlled by environmental cues. In this report, we show that determinant signals for lateral somite specification are provided by the lateral plate. They result in a blockade of the myogenic program, which maintains the lateral somitic cells as undifferentiated muscle progenitors expressing the Pax-3 gene, and represses the activation of the MyoD family genes. In vivo, this mechanism could account for the delay observed in the onset of myogenesis between muscles of the epaxial and hypaxial domains.

Assessment of a simplified experimental procedure to evaluate impact sound reduction of floor coverings

The impact noise reduction provided by floor coverings is usually obtained in laboratory, using the methodology described in the standard EN ISO 140-8, which requires the use of standard acoustic chambers. The construction of such chambers, following the requirements described in the EN ISO 140-1, implies a significant investment, and therefore only a limited number exists in each country. Alternatives to these standard methodologies, that allow a sufficiently accurate evaluation and require lower resources, have been interesting many researchers and manufacturers. In this paper, one such strategy is discussed, where a reduced sized slab is used to determine the noise reduction provided by floor coverings, following the procedure described in the ISO/CD 16251-1 technical document. Several resilient coverings, floating floors and floating slabs are tested and the results are compared with those obtained using the procedures described in the standards EN ISO 140-8 and EN ISO 717-2.

Celebrity endorsers' performance on the “ground” and on the “floor”

This article analyzes the relationship between two types of performances, one on the ground (of a tennis court) and the other on the floor (of the stock market). The empirical application looks into the tennis player, Rafael Nadal, and his endorsing firms. The findings show a positive reaction in the market value when the tennis player wins matches in the Grand Slams, the intriguing effect being the diminishing sensitivity pattern that such reaction shows and the absence of loss aversion.

Photographic prints of the elevations and floor plans of Harvard College or "Old College" used for publication by Samuel E. Morison, February 1933

Contains seven photographic prints elevations and floor plans of Harvard College used in an article on "Old College" by Samuel E. Morison. Includes first, second, and third floor plans; north, south, and east elevations; and one overhead perspective of the structure.

First Floor, Old Harvard Hall 1667-1764, 1935

Floor plan of the first floor of Old Harvard Hall drawn by H.R. Shurtleff in 1935. Includes the hall, kitchen, buttery, and two chambers

Second Floor, Old Harvard Hall, 1677-1764, 1935

Floor plan of the second floor of Old Harvard Hall drawn by H.R. Shurtleff in 1935. Includes student chambers, tutor chambers, and the library.

First Floor, Hollis Hall, 1874

Floor plan of renovations for the first floor of Hollis Hall, as drawn by William Rotch Ware in 1874. Includes dimensions for student chambers, hallways, and coal furnaces.

Second Floor, Hollis Hall, 1874

Floor plan of renovations for the second floor of Hollis Hall, as drawn by William Rotch Ware in 1874. Includes dimensions for proctor's rooms, student chambers, hallways, and coal furnaces.

Third Floor, Fourth Floor, Hollis Hall, 1874

Floor plan of renovations for the third and fourth floors of Hollis Hall, as drawn by William Rotch Ware in 1874. Includes dimensions for Pi Eta Society rooms, student chambers, hallways, and coal furnaces.

Hollis Hall, Harvard College, Cambridge, Middlesex Co., Mass., Second Floor Plan, (photostat copy), [1934]

Partial photostat copy of Sheet 2 of 10.

First Floor, Stoughton, 1874

Floor plan of renovations for the first floor of Stoughton Hall, as drawn by William Rotch Ware in 1874. Includes dimensions for student chambers, hallways, and coal furnaces.

Second Floor, Stoughton, 1874

Floor plan of renovations for the second floor of Stoughton Hall, as drawn by William Rotch Ware in 1874. Includes dimensions for student chambers, proctor's rooms, hallways, and coal furnaces.