Infrared-A Irradiation-induced Inhibition of Human Keratinocyte Proliferation and Potential Mechanisms.

Infrared-A (IRA), which can penetrate deeply into the human skin, is a major component of solar radiation and is recognized to promote photoaging of human dermis. To our knowledge, however, the cellular and molecular consequences of human epidermis exposure to IRA have not been clarified. Thus, we investigated whether IRA inhibits the proliferation of normal human epidermal keratinocytes (NHEKs). IRA irradiation ed in cell cycle arrest at G1 and a dose-dependent reduction in the proliferation of NHEKs. We found that mechanistic target of rapamycin complex 1 (mTORC1) was initially inactivated during IRA irradiation due to the formation of stress granules (SGs), and this inactivation was maintained for at least 6 h after irradiation due to Akt dephosphorylation. Furthermore, repeated exposure of human skin equivalents to IRA led to marked thinning of the epidermal cell layer. In conclusion, IRA irradiation inhibits mTORC1 activity possibly through two molecular mechanisms involving SG formation in the early-phase and subsequent Akt dephosphorylation. This sequential mechanism seems to cause G1 cell cycle arrest and a reduction in cell proliferation, supporting the hypothesis that the decreased proliferation of basal keratinocytes that occurs during skin aging might be partly attributable to IRA radiation.

Traumatic Gastric Perforation Associated with Cardiopulmonary Resuscitation: A Case Report.

Sternal and rib fractures are well-known complications of cardiopulmonary resuscitation (CPR). We experienced a rare case of traumatic gastric perforation associated with CPR that required emergency laparotomy. In this case, we examined whether surgery is essential for gastric perforation associated with CPR. A 67-year-old man experienced cardiopulmonary arrest in the workplace, and bystander CPR was performed by his colleagues. He was then transported by ambulance to our hospital. A large amount of free air was found in the peritoneal cavity on computed tomography at presentation, and perforation of the gastrointestinal tract was suspected. During emergency laparotomy, a 2-cm serosal-muscular layer tear was found in the gastric lesser curvature. The damaged stomach wall was repaired, the abdominal cavity was lavaged, and surgery was completed by placing a drainage tube. The patient's postoperative course was good and he was discharged on the 26th postoperative day. Emergency laparotomy has been performed frequently for traumatic gastric perforation associated with CPR. However, emergency laparotomy may be avoided by conservative treatment in some cases. Traumatic gastric perforation associated with CPR is a serious complication; however, the life prognosis of cardiopulmonary arrest patients depends on the original disease and the success of CPR. Traumatic gastric perforation associated with CPR is rarely fatal, and bystanders should not hesitate to initiate CPR.