Results of various operations for sacrococcygeal pilonidal disease.

A comparative evaluation of 4 operations designed to treat sacrococcygeal pilonidal disease is presented, to show the duration of treatment time and the recurrence rate. Case records of 112 patients (131 operations) were studied. The results indicate that the healing times with the excision and Z-plasty operation are clearly less than those obtained by incision with drainage and packing, excision with primary closure, or excision and lay open. The overall recurrence rate in this series was 28 percent, all occurring within 3 years of the first operation. With the exception of the Z-plasty operation, other methods required considerable outpatient treatment time and were more susceptible to recurrence. We suggest that by reconstructing the intergluteal cleft, the likely effect of the Z-plasty operation is to eliminate factors that may promote pilonidal disease in this region.     

Radiation resistance of Deinococcus radiodurans R1 with respect to growth phase

Deinococcus species exhibit an extraordinary ability to withstand ionizing radiation (IR). Most of the studies on radiation resistance have been carried out with exponential phase cells. The studies on radiation resistance of Deinococcus radiodurans R1 with respect to different phases of growth showed that late stationary phase cells of D. radiodurans R1 were fourfold more sensitive to IR and heat as compared with exponential or early stationary phase cells. The increased sensitivity of D. radiodurans R1 to IR in the late stationary phase was not due to a decrease in the intracellular Mn/Fe ratio or an increase in the level of oxidative protein damage. The resistance to IR was restored when late stationary phase cells were incubated for 15 min in fresh medium before irradiation, indicating that replenishment of exhausted nutrients restored the metabolic capability of the cells to repair DNA damage. These observations suggest that stress tolerance mechanisms in D. radiodurans R1 differ from established paradigms.