Suspected skeletal dysplasias: femur length to abdominal circumference ratio can be used in ultrasonographic prediction of fetal outcome

OBJECTIVES: Skeletal dysplasias are a group of bone growth disorders, some of which can be recognized prenatally. Certain types of skeletal dysplasias result in a lethal fetal outcome. The ability to predict this outcome prenatally would be important in counseling parents. This study evaluated the ratio of femur length to abdominal circumference as a predictor of fetal outcome in cases of suspected skeletal dysplasia. STUDY DESIGN: This 3-year retrospective study identified 18 cases of prenatally suspected skeletal dysplasia from a population of approximately 35,000 fetuses undergoing prenatal ultrasonography. The femur length/abdominal circumference ratio was calculated and compared with fetal-neonatal outcomes and diagnoses. RESULTS: Eighteen cases of suspected skeletal dysplasia were identified, and the femur length/abdominal circumference ratio was found to be a good predictor of fetal outcome independent of gestational age. A ratio < 0.16 resulted in a lethal outcome in nine of nine cases. Conversely, a ratio > or = 0.16 resulted in a diagnosis of a nonlethal form of skeletal dysplasia or a diagnosis that ruled out any form of skeletal dysplasia in nine of nine cases. CONCLUSIONS: The femur length/abdominal circumference ratio may be useful to predict a lethal fetal outcome when ultrasonography indicates a possible skeletal dysplasia.     

Structural polymorphism of the RecA protein from the thermophilic bacterium Thermus aquaticus

The Escherichia coli RecA protein has served as a model for understanding protein-catalyzed homologous recombination, both in vitro and in vivo. Although RecA proteins have now been sequenced from over 60 different bacteria, almost all of our structural knowledge about RecA has come from studies of the E. coli protein. We have used electron microscopy and image analysis to examine three different structures formed by the RecA protein from the thermophilic bacterium Thermus aquaticus. This protein has previously been shown to catalyze an in vitro strand exchange reaction at an optimal temperature of about 60 degrees C. We show that the active filament formed by the T. aquaticus RecA on DNA in the presence of a nucleotide cofactor is extremely similar to the filament formed by the E. coli protein, including the extension of DNA to a 5.1-A rise per base pair within this filament. This parameter appears highly conserved through evolution, as it has been observed for the eukaryotic RecA analogs as well. We have also characterized bundles of filaments formed by the T. aquaticus RecA in the absence of both DNA and nucleotide cofactor, as well as hexameric rings of the protein formed under all conditions examined. The bundles display a very large plasticity of mass within the RecA filament, as well as showing a polymorphism in filament-filament contacts that may be important to understanding mutations that affect surface residues on the RecA filament.     

Professional drivers: protection needed for a high-risk occupation

"On the job" motor vehicle deaths number more than 4,000 annually in the U.S. and comprise nearly one-third of all work-related deaths. Yet the Department of Labor has set no standards relating to on-the-road safety of the millions of workers whose jobs entail large amounts of driving, and Department of Transportation standards affecting occupational safety cover only drivers in interstate commerce. Drivers of some commercial vehicles, such as heavy trucks, are at special risk of injury because trucks have usually been exempted for many years from federal motor vehicle safety standards--such as standards for brakes and seatbelts--designed to prevent crashes or protect occupants in crashes. Observations based on a series of 150 fatal crashes involving tractor trailers illustrate the need for better protection of this large population of high-risk workers. Clarification of responsibility within the various federal agencies and application of available knowledge and technology are essential.     

Expression of an inter-alpha-trypsin inhibitor heavy chain-like protein in the pig endometrium during the oestrous cycle and early pregnancy

Triploidies are pregnancies that show a 69 chromosome karyotype. This chromosomal abnormality gives rise to early abortion in most cases. Triploid pregnancies, after the first three months, become molar pregnancies (molar changes inside the placenta with identifiable embryonic structures and a preeclampsia) or non molar pregnancies (isolated intauterin growth retardation). Several possibilities concerning the origin of the additional set of chromosomes exist: dispermy (the most common), diandry and digyny. The maternal and fetal clinical manifestations of this chromosomal abnormality are very diverse, which explains the difficulty of finding and recognizing this pathology. Mac Fadden's classification does not explain all the phenotypic triploid physiopathology. Formal diagnosis of triploidy depends on the fetal karyotype. The better the maternal prognosis is, the worst the fetal prognosis is. Postnatal life expectancy is not more than a few weeks. In most cases, maternal associated complications disappear with the molar evacuation. The risk of post molar tumor is discussed. However, good management of triploidy is based on an early diagnosis, before birth if that is possible.     

An examination of spatial variation in mercury concentrations in otter (Lutra canadensis) in south-central Ontario

Hair samples were collected from otter (Lutra canadensis) trapped in several parts of south-central Ontario, Canada. The concentrations of total Hg in hair were compared with methyl mercury concentrations in liver tissues from the same individuals to determine if hair is a suitable monitoring tissue. Hg in the two tissues was significantly correlated. Hair was used to monitor Hg in 51 individuals from four townships. The concentrations of total Hg in hair ranged from 4 to 20 micrograms/g. No significant variation among the four sample regions existed. Generally the highest concentrations were found in the youngest members of the population. Some possible explanations for the observations are presented.