Single-incision cholecystectomy in a patient with situs inversus totalis presenting with cholelithiasis: A case report.

Laparoscopic cholecystectomy has become the gold standard for the treatment of cholelithiasis, and many reports of single-incision laparoscopic cholecystectomy have been published in the past few years. Situs inversus totalis is a very rare condition, but the variant anatomy should not preclude a minimally invasive approach to surgery. We report a case of successful single-port laparoscopic cholecystectomy in a patient with situs inversus totalis, describe the technical advantages, and review the literature.

The N-terminal 15-48 region of cyclin kinase inhibitor p21 is a determinant of basal expression.

The cyclin kinase inhibitor, p21, inhibits or arrests cell cycle progression in response to DNA damage and regulates the progression of apoptosis, either negatively or positively depending on the situation. The stability of p21 is regulated by its phosphorylation or through binding with partner molecules, and, when cells grow without DNA damage, the level of p21 is regulated by proteasome degradation. In this study, we analyzed the mechanism by which the basal expression level of p21 is stabilized. The transient expression of various p21 deletion mutants revealed a specific mutant with a deletion of 15-48 aa (Delta15-48C) that was extremely unstable. This mutant was stabilized by the proteasome inhibitor, lactacystin. Since the cysteine in the region of the alanine mutant did not destabilize p21, possible disulfide bonds formed by cysteines in the region are not responsible for the stabilization. The Delta15-48C was unstable in the cells stably expressing the 1-60 aa region, indicating that the 1-60 aa region did not function in trans. Fusion of the 1-60 aa fragment to the N-terminal of Delta15-48C stabilized the product, indicating that the 1-60 aa region in the molecule is effective for the stabilization. We constructed cells that stably expressed Delta15-48C. The Delta15-48C was unstable, but was stabilized by lactacystin. Irradiation (5 Gy) enhanced the expression of Delta15-48C without elevation of mRNA levels and increased the binding with cyclin A or CDK2. Taken together, the 15-48 aa region of p21 is essential for basal expression by preventing degradation by the proteasome, which is distinct from the mechanism induced by DNA damage.

Cytoplasmic Localization of Cyclin Kinase Inhibitor p21 Delays the Progression of Apoptosis.

The different functions of the cyclin kinase inhibitor, p21, rely on its localization to either the cytoplasm or nucleus. Phosphorylation at Thr-145 and/or Ser-146 was reported to target p21 to the cytoplasm. To clarify the function of cytoplasmic p21, we constructed non-phosphorylatable mutants, Thr-145 to Ala (T145A) and Ser-146 to Ala (S146A), and phosphorylation mimic mutants, Thr-145 to Asp (T145D) and Ser-146 to Asp (S146D), and the cells stably expressing those mutants were identified. The association of all four mutants with either CyclinA or CDK2 was increased by Á-irradiation, indicating that the mutants functioned as cyclin kinase inhibitors. PCNA binding was detected in T145A and S146A, but not in T145D and S146D. In the stably-expressing cells, T145D and S146D binding was observed in the cytoplasm, while T145A and S146A in the nucleus. Further, lactacystin treatment enhanced T145A and S146A, but not T145D and S146D, which is consistent with the degradation of p21 by proteasome in the nucleus. Apoptosis induced by Á-irradiation was delayed in the cells expressing either T145D or S146D. The activities of caspase 3 were not reduced in mutant-expressing cells. These results suggest that the PCNA-unbound form of the full length p21 in the cytoplasm delays apoptosis through the interaction with caspase 3 or downstream components.