Charge recombination in DNA hairpins controlled by counterions.

The slow charge recombination in DNA hairpins of various lengths is investigated. The distance dependence for the charge recombination rate between stilbene donor (Sd(+)) and stilbene acceptor (Sa(-)) linkers separated by AT bridges of various lengths has the double exponential form. We suggest that this puzzling dependence is associated with two tunneling channels distinguished by the presence or absence of a Cl(-) counterion bound to an Sd(+) linker.

Adult prostatic sarcoma.

A 57-year-old male with a high grade leiomyosarcoma of the prostate is presented. The local extent of the tumor was accurately described by magnetic resonance imaging (MRI). Following chemotherapy, the tumor volume was reduced by 60% and was judged to be clinically resectable by MRI.

Imaging of peritoneal pathology.

Advances in the imaging of peritoneal pathology are reviewed. Papers published in the past year in the radiologic, surgical, and pediatric literature discussed the detection, quantification, characterization, and management of fluid collections in the trauma patient or the patient with intra-abdominal sepsis; the assessment of various imaging modalities in the evaluation of unexplained fever or pain; and the detection, characterization, and localization of primary, recurrent, or metastatic abdominal neoplasms.

Varicoceles. Radiologic diagnosis and treatment.

The association of clinically apparent varicoceles with male subfertility and infertility has been noted in the urology literature since the late nineteenth century, and surgical ligation of varicoceles has been considered appropriate therapy in an attempt to improve semen quality and increase fertility for the past 40 years. It has been established by several authors cited herein that varicocele size does not predict prognosis after ligation reliably. Because subclinical varicoceles may affect testicular function and histologic characteristics adversely and because age at time of therapy may affect probability of successful enhancement of fertility, the interest of radiologists and urologists has been directed toward diagnosis and treatment of both clinically obvious and clinically occult varicoceles, particularly in young adult men or adolescent boys.