A dust-enshrouded tidal disruption event with a resolved radio jet in a galaxy merger.

Tidal disruption events (TDEs) are transient flares produced when a star is ripped apart by the gravitational field of a supermassive black hole (SMBH). We have observed a transient source in the western nucleus of the merging galaxy pair Arp 299 that radiated >1.5 × 1052 erg at infrared and radio wavelengths but was not luminous at optical or x-ray wavelengths. We interpret this as a TDE with much of its emission reradiated at infrared wavelengths by dust. Efficient reprocessing by dense gas and dust may explain the difference between theoretical predictions and observed luminosities of TDEs. The radio observations resolve an expanding and decelerating jet, probing the jet formation and evolution around a SMBH.

Dental maturity is advanced in Fragile X syndrome.

Fragile X (FraX) syndrome is the most common cause of inherited mental retardation. The FraX gene (FMR1) has been cloned, and the mutation causing the disease is now known. We estimated the effect of FraX on dental development in 28 affected boys (aged 4.9-17.6 years) and three carrier girls (aged 5.8, 10.4, and 12.7 years). Dental maturity, assessed on the basis of formation [Demirjian A, Goldstein H. 1976: Ann Hum Biol 3:411-421] and of emergence [Hägg U, Taranger J. 1985: Angle Orthod 55:93-107], was compared with growth in stature and skeletal maturity. The mean relative dental age was advanced in FraX males, based on formation (+1.4 SD) and on emergence (+1.1 SD). More pronounced advancement was seen in younger children. Dental maturity was advanced in heterozygous carrier girls as well. Height and skeletal maturity did not show a similar trend toward advanced development.

Craniofacial and dental characteristics of Silver-Russell syndrome.

We found significant differences in a craniometric, cephalometric, and dental study of 19 Silver-Russell syndrome patients (13 without growth hormone treatment) with appropriate controls. Although head circumference was normal for age, head length was increased, while cranial and facial widths and facial heights were reduced. Posterior facial height, posterior cranial base length, cranial base height, and mandibular body size were significantly smaller than in healthy children of the same height. Articulatory speech disorders were common. Enamel defects pointed to an early prenatal insult. Delayed dental age and small mandibular and cranial base dimensions support the possibility of physiological growth hormone deficiency in many Silver-Russell syndrome children; however, facial soft tissue structures were strikingly different from those observed in classical growth hormone deficiency.

MSX1 gene is deleted in Wolf-Hirschhorn syndrome patients with oligodontia.

Abnormalities of the short arm of chromosome 4 cause multiple congenital malformations, including craniofacial, oral, and dental manifestations. A candidate gene for oral defects in this region is MSX1, which is mandatory for normal oral and tooth development. We examined the dentition and the presence of MSX1 in eight Finnish patients with abnormalities of 4p, including seven cases of Wolf-Hirschhorn syndrome. Five of the Wolf-Hirschhorn syndrome patients presented with agenesis of several teeth, suggesting that oligodontia may be a common (even though previously not well-documented) feature in Wolf-Hirschhorn syndrome. In fluorescence in situ hybridization (FISH) analysis, the five patients with oligodontia lacked one copy of MSX1, while the other three had two hybridization signals. One of these presented with the only case of cleft palate among the patients. Our result confirms that haploinsufficiency for MSX1 serves as a mechanism that causes selective tooth agenesis but, alone, is not enough to cause oral clefts.