Regulating axon branch stability: the role of p190 RhoGAP in repressing a retraction signaling pathway.

Mechanisms that regulate axon branch stability are largely unknown. Genome-wide analyses of Rho GTPase activating protein (RhoGAP) function in Drosophila using RNA interference identified p190 RhoGAP as essential for axon stability in mushroom body neurons, the olfactory learning and memory center. p190 inactivation leads to axon branch retraction, a phenotype mimicked by activation of GTPase RhoA and its effector kinase Drok and modulated by the level and phosphorylation of myosin regulatory light chain. Thus, there exists a retraction pathway from RhoA to myosin in maturing neurons, which is normally repressed by p190. Local regulation of p190 could control the structural plasticity of neurons. Indeed, genetic evidence supports negative regulation of p190 by integrin and Src, both implicated in neural plasticity.

Fetal ovarian cysts: prenatal ultrasonographic detection and postnatal evaluation and treatment.

Ovarian cysts were diagnosed by antenatal ultrasonographic examination in 15 fetuses between 19 and 37 weeks' gestation. In six cases there was ultrasonographic evidence of torsion. Intracystic flocculation, which typically was deposited on the sloping part of the cyst, gave a characteristic liquid interface that was regarded as ultrasonographic evidence of torsion. All cases with evidence of torsion were managed surgically post partum, and in all patients this complication was confirmed. The remaining nine cases were followed up by repeated ultrasonograms, and in all patients disappearance of the cyst was documented within the first 6 months of life. The mean size of cysts with evidence of torsion was 5.41 +/- 0.25 cm, and the mean size of those without torsion was 4.33 +/- 0.3 cm (p less than 0.01). Histologic examination of the surgical specimen in the cases with evidence of torsion revealed follicular cysts in three cases and necrotic ovarian cysts with no specific epithelial findings in the remaining three. We recommend continuous ultrasonographic assessment of antenatally diagnosed cysts and believe that the choice of treatment depends on the appearance of the cyst and its evolution throughout pregnancy.

[Limp as a presenting symptom of psoas muscle inflammation].

Inflammatory irritation of the psoas muscle in children is rare. The initial diagnosis may be difficult because of the similarity between the symptoms of psoas muscle inflammation and septic hip joint. We present a boy and a girl, both 3.5 years old, with psoas muscle inflammation, whose initial clinical and laboratory findings could be explained by either septic hip joint or osteomyelitis. Both presented with fever and limp. 1 developed an acute abdomen within 3 days and at operation a retrocecal periappendicular abscess was found. In the other, left lower quadrant, abdominal pain developed 4 days following admission and ultrasonic findings indicated a left psoas muscle abscess. We suggest that psoas muscle inflammation should be added to the differential diagnosis of limp in children. Early correct diagnosis can be established by proper physical examination, including rectal examination, and with the aid of diagnostic tools such as ultrasound, computerized tomography or both.