Genetics of cleft lip and palate.

Cleft lip with or without cleft palate (CL/CP) is one of the most common structural birth defects, with treatment including multiple surgeries, speech therapy, and dental and orthodontic treatments over the first 18 years of life. As a result of the treatment interventions, pediatric nurses may be required to care for these children beginning in infancy through adolescence. Providing care for these patients and families can include educating patients and parents about the genetics of CL/CP, as well as meeting their immediate medical needs. A basic overview of normal lip and palate development, classification of clefts, pathophysiology of CL/CP, incidence, inheritance, genetic and environmental causes, genetic counseling, prenatal diagnosis, fetal surgery, and nursing implications is provided to educate pediatric nurses about the basics of the genetics of CL/CP.

Beyond Pierre Robin sequence.

The label Pierre Robin sequence is given to infants presenting with a triad of specific congenital anomalies: micrognathia, glossoptosis, and cleft palate. However, this label should be considered the first, not the final, step in the diagnostic process. In approximately 80 percent of newborns with Pierre Robin sequence, the triad of anomalies is part of an underlying genetic condition. This article reviews the variable etiologies of and general clinical considerations for Pierre Robin sequence. To illustrate how clinical management might vary based on the identification of an underlying condition, three case examples of neonates with Pierre Robin sequence and different underlying genetic conditions are presented.

Genetic family history assessment.

The purpose of this article is to familiarize nurses with why, how, when, and where a genetic family history assessment should be used in clinical practice. Pedigrees are diagrams that display the relationship among family members by using a combination of symbols and lines. They are used to record concisely a complete family history to identify the risk of transmitting inherited condition, to identify people at risk for development of adult-onset conditions, to aid in clinical diagnosis, and to serve as a reference for social and biologic relationships. A detailed explanation of the standardized pedigree nomenclature that was recommended by the Pedigree Standardization Task Force in 1995 is included. Step-by-step guidelines on taking a genetic family history and drawing pedigrees are provided. A case study is also included to illustrate pedigree construction.

Lunar laser ranging: a continuing legacy of the apollo program.

On 21 July 1969, during the first manned lunar mission, Apollo 11, the first retroreflector array was placed on the moon, enabling highly accurate measurements of the Earthmoon separation by means of laser ranging. Lunar laser ranging (LLR) turns the Earthmoon system into a laboratory for a broad range of investigations, including astronomy, lunar science, gravitational physics, geodesy, and geodynamics. Contributions from LLR include the three-orders-of-magnitude improvement in accuracy in the lunar ephemeris, a several-orders-of-magnitude improvement in the measurement of the variations in the moon's rotation, and the verification of the principle of equivalence for massive bodies with unprecedented accuracy. Lunar laser ranging analysis has provided measurements of the Earth's precession, the moon's tidal acceleration, and lunar rotational dissipation. These scientific results, current technological developments, and prospects for the future are discussed here.

Earth rotation measured by lunar laser ranging.

The estimated median accuracy of 194 single-day determinations of the earth's angular position in space is 0.7 millisecond (0.01 arc second). Comparison with classical astronomical results gives agreement to about the expected 2-millisecond uncertainty of the 5-day averages obtained by the Bureau International de l'Heure. Little evidence for very rapid variations in the earth's rotation is present in the data.

The Lunar Laser Ranging Experiment: Accurate ranges have given a large improvement in the lunar orbit and new selenophysical information.

The lunar ranging measurements now being made at the McDonald Observatory have an accuracy of 1 nsec in round-trip travel time. This corresponds to 15 cm in the one-way distance. The use of lasers with pulse-lengths of less than 1 nsec is expected to give an accuracy of 2 to 3 cm in the next few years. A new station is under construction in Hawaii, and additional stations in other countries are either in operation or under development. It is hoped that these stations will form the basis for a worldwide network to determine polar motion and earth rotation on a regular basis, and will assist in providing information about movement of the tectonic plates making up the earth's surface. Several mobile lunar ranging stations with telescopes having diameters of 1.0 m or less could, in the future, greatly extend the information obtainable about motions within and between the tectonic plates. The data obtained so far by the McDonald Observatory have been used to generate a new lunar ephemeris based on direct numerical integration of the equations of motion for the moon and planets. With this ephemeris, the range to the three Apollo retro-reflectors can be fit to an accuracy of 5 m by adjusting the differences in moments of inertia of the moon about its principal axes, the selenocentric coordinates of the reflectors, and the McDonald longitude. The accuracy of fitting the results is limited currently by errors of the order of an arc second in the angular orientation of the moon, as derived from the best available theory of how the moon rotates in response to the torques acting on it. Both a new calculation of the moon's orientation as a function of time based on direct numerical integration of the torque equations and a new analytic theory of the moon's orientation are expected to be available soon, and to improve considerably the accuracy of fitting the data. The accuracy already achieved routinely in lunar laser ranging represents a hundredfold improvement over any previously available knowledge of the distance to points on the lunar surface. Already, extremely complex structure has been observed in the lunar rotation and significant improvement has been achieved in our knowledge of lunar orbit. The selenocentric coordinates of the retroreflectors give improved reference points for use in lunar mapping, and new information on the lunar mass distribution has been obtained. Beyond the applications discussed in this article, however, the history of science shows many cases of previously unknown, phenomena discovered as a consequence of major improvements in the accuracy of measurements. It will be interesting to see whether this once again proves the case as we acquire an extended series of lunar distance observations with decimetric and then centimetric accuracy.

Laser ranging retro-reflector: continuing measurements and expected results.

After successful acquisition in August of reflected ruby laser pulses from the Apollo 11 laser ranging retro-reflector (LRRR) with the telescopes at the Lick and McDonald observatories, repeated measurements of the round-trip travel time of light have been made from the McDonald Observatory in September with an equivalent range precision of +/-2.5 meters. These acquisition period observations demonstrated the performance of the LRRR through lunar night and during sunlit conditions on the moon. Instrumentation activated at the McDonald Observatory in October has yielded a precision of +/-0.3 meter, and improvement to +/-0.15 meter is expected shortly. Continued monitoring of the changes in the earth-moon distance as measured by the round-trip travel time of light from suitably distributed earth stations is expected to contribute to our knowledge of the earth-moon system.