Analysis of DNA damage induced by nitrosourea derivatives in rat brain tumor cells using a sequencing procedure

DNA damages caused by various anticancer nitrosourea compounds such as ACNU and MCNU were studied. Reiterated fragments of 167 and 203 base pairs (bp) were obtained after Hind III and Hae III restriction endonuclease digestion of 9L rat brain tumor DNA. The end-labeled reiterated fragments were reacted with ACNU and MCNU, which resulted in the scission breaks corresponding to the locations of guanine on an extended Maxam-Gilbert sequencing gel. Subsequent piperidine hydrolysis yielded scission products more frequently. These results indicate that nitrosoureas such as ACNU and MCNU generate DNA scission breaks and/or alkali-labile sites preferentially at the position of guanine moieties in rat brain tumor DNA.     

In vitro damage of isolated DNA from two brain tumor cell lines induced by a water-soluble antitumor nitrosourea

We report the DNA sites damaged by the antitumor drug, nimustine hydrochloride (ACNU), in highly reiterated DNA sequences of rat glioma cells. A reiterated fragment of 370 base pairs (bp), obtained after Hind III restriction endonuclease digestion of rat glioma C6 or 9L cells DNA, was divided into 167 and 203 bp by subsequent Hae III enzyme reaction. The reaction of end-labelled 167 and 203 bp fragments with ACNU resulted in scission breaks corresponding to the locations of guanine. Moreover, ACNU and subsequent piperidine hydrolysis produced more frequent breaks of the phosphodiester bonds at the guanine positions, thus forming alkali-labile sites. These results indicate that the preferred site of DNA strand scission induced by ACNU is at guanine positions.     

Operative position suitable for transvaginal excision of urethral diverticulum or closure of urethrovaginal fistula

Among the various surgeries in female urology, transvaginal excision of urethral diverticulum needs careful and meticulous procedures in order to avoid some operative complications, such as urethral stricture or urethrovaginal fistula. In the present report, we present a woman with urethral diverticulum who initially underwent transvaginal excision of diverticulum in the dorsal lithotomy position, but she was complicated with urethrovaginal fistula postoperatively. Unfortunately, we failed to repair her fistula when she underwent excision of the fistula in the dorsal lithotomy position. With reconsideration of an operative position useful for transvaginal surgery, we succeeded in fistula closure in the Jackknife prone reverse-lithotomy position, and thereafter, two subsequent patients with urethral diverticulum were successfully treated with transvaginal excision of diverticulum in this operative position. In the transvaginal approach to the peri-urethral disorders, the Jackknife prone reverse-lithotomy position was notably superior to the dorsal lithotomy position with the following advantages: (1) the surgeons can easily operate in a bright and large surgical site without any blind view. (2) the surgeons can dissect and suture safely and accurately. (3) the assistants also can help in the operation bimanually in the same view as the surgeon when the posterior vaginal wall is fixed with a retractor.     

An autopsy-proven case of myeloperoxidase-antineutrophil cytoplasmic antibody-positive polyarteritis nodosa with acute renal failure and alveolar hemorrhage

An 80-year-old woman positive for myeloperoxidase-antineutrophil cytoplasmic antibody (MPO-ANCA) was admitted with a 3-month history of fever, general malaise, and weight loss, after unsuccessful treatment with antibiotics. Upon admission, her fever persisted, and there was concomitant deterioration of renal function without active urine sediments. Furthermore, she developed hemoptysis, and chest computed tomography (CT) scan revealed bilateral diffuse alveolar hemorrhage. Although a renal biopsy was not performed because of her dementia, we initially suspected microscopic polyangiitis (MPA) on the basis of her clinical course. Because of her poor general condition, she was administered a low dose of prednisolone. Although her fever subsided, she suffered from intractable alveolar hemorrhage and eventually died from respiratory failure. During the autopsy, fibrinoid necrosis was restricted to medium-sized arteries, including the arcuate arteries of the kidneys and the bronchial arteries, without necrotizing crescentic glomerulonephritis and alveolar capillaritis. Therefore, polyarteritis nodosa (PAN) was diagnosed. It is important to distinguish between MPA and PAN because they can lead to life-threatening complications, and their treatment strategies and prognosis are different. When a patient presents with MPO-ANCA, alveolar hemorrhage, and acute renal failure with little evidence of glomerulonephritis, a differential diagnosis of PAN should be made; however, it is difficult to do so without pathological findings. Therefore, pathological examination should be carried out whenever possible.     

Polyamines as an inhibitor on erythropoiesis of hemodialysis patients by in vitro bioassay using the fetal mouse liver assay

The pathogenesis of anemia in patients with chronic renal failure has been greatly attributed to erythropoietin (EPO) deficiency. Recently, however, there has been some thought that uremic inhibitors might suppress the activity of EPO and reduce the maturation of erythropoiesis. Polyamines are well known to be involved in the regulation of cellular proliferation and differentiation. Furthermore, the polyamine levels in the serum or erythrocytes are elevated in chronic hemodialysis patients, and can be lowered immediately by hemodialysis. In the present study, we first measured the polyamines levels (putrescine, spermidine, spermine) by high performance liquid chromatography (HPLC) in 20 chronic hemodialysis patients, and investigated the effects of polyamines on erythropoiesis by in vitro bioassay using fetal mouse liver cells. The direct effects of polyamines in erythroid colony formation in the medium with and without EPO were evaluated. Each polyamine level in chronic hemodialysis patients was higher than in the healthy subjects, and a significant negative correlation was found between polyamines and erythropoiesis. Polyamines inhibited the activity of EPO, but they did not have any direct effect on colony formation of the fetal mouse liver cells. These results suggest that polyamines have inhibitory effects on the proliferation or maturation of erythroid precursor cells and are intimately involved in the pathogenesis of renal anemia in chronic hemodialysis patients.