Katsumi Iwase

A 60-year-old single female was seen at the hospital because of a tumor in the upper outer quadrant of left breast in August 1992. On physical examination, the tumor was 2.0cm in diameter, hard, and rough-surfaced. No axillary lymph node was palpable. Ultrasonography showed an irregular shaped mass, 2.2×1.2cm in size, with a heterogenous hypoechoic level inside, which suggested a malignant tumor. Aspiration cytology indicated that the tumor was suspiciously carcinoma.<br> Therefore, the tumor was excised under general anesthesia on September 21st, 1992. The excised tumor was diagnosed with juvenile fibroadenoma of the breast by intraoperative rapid histological examination. Re-examination of permanent specimens of the tumor, however, revealed a lobular car-cinoma in situ, 2×3mm in size, at the narrow part of the gourd-shaped fibroadenoma.<br> Fibroadenoma is usually found in young females, but rarely in old ones. Fibroadenoma has been reported to happen to accompany with lobular carcinoma. So far only 12 cases of breast carcinoma in fibroadenoma have been reported in Japan and six cases of them had lobular carcinoma. In addition lobular carcinoma in situ in fibroadenoma of the breast has been scarcely seen in old patients over 50 year old in the world.

Kidney function is regulated by several hormones which act through adenylate cyclasecyclic AMP system. The present study was undertaken to investigate cyclic AMP- and cyclic GMP-phosphodiesterase (cAMP-PDE and cGMP-PDE respectively) activities in the rat kidney, and also the effect of several hormones affecting the kidney function on these enzyme activities in vitro. <BR>Rat kidneys were separated into cortex and medulla. These were homogenized in 50 mM Tris-HC1 buffer, pH 7.5, containing 0.32 M sucrose and fractionated by centrifugation. PDE activity was measured in all fractions, using the two-step assay system. A low substrate concentration (0.5 μM) was used, unless otherwise stated. <BR>Substantial activity was present in all of the fractions and most of the activity existed in the soluble fraction (105000 × g supernatant). Cyclic GMP-PDE activity was dominant in both cortex and medulla. The rat kidney contained two forms of cAMP-PDE, one of which had a Km of 2.0 × 10^-4M and another which had a low Km of 2.5 × 10^-5M, and one form of cGMP-PDE with a Km of 2.5 × 10^-5M. These cAMP-PDE and cGMP-PDE were purified by Sepharose-6B column chromatography. Cyclic AMP-PDE activity was found in a broad area associated with two peaks and cGMP-PDE activity had one peak corresponding to the same peak as the hgih molecular weight cAMP-PDE. Calmodulin was eluted after the peak of cGMP-PDE activity. Both cAMP-PDE and cGMP-PDE activities were inhibited by calcium ion at a concentration of more than 5.0 × 10^-4M. Cyclic GMP-PDE activity was not activated by calmodulin in the presence of enough calcium ion.<BR>The effect of 1α, 25(OH)₂ Vit D₃, parathyroid hormone (PTH), antidiuretic hormone (ADH), calcitonin (CT), angiotensin II, and trichrolomethiazide on the partially purified cAMP-PDE and cGMP-PDE activities were examined. 1α, 25(OH)₂ Vit D₃ activated cAMP-PDE activity and did not affect cGMP-PDE activity. The concentrations of 1α, 25(OH)₂ Vit D₃ producing 50% activation of cAMP-PDE activity were 5.0 × 10^-11M (cortex) and 6.7 × 10^-10M (medulla). CT and ADH inhibited both cAMP-PDE and cGMP-PDE activities. The concentrations of CT producing 50% inhibition of cAMP-PDE activity were 4.0 ×10^-5M (cortex) and 3.3 × 10^-7M (medulla), and those of cGMP-PDE activity were 1.0 × 10^-5M (cortex) and 1.0 × 10^-4M (medulla). Concerning ADH, the concentrations required for 50% inhibition of cAMP-PDE activity were 5.3 × 10^-6M (cortex) and about 1.0 × 10^-3M (medulla), and those of cGMP-PDE activity were 5.3 × 10^-3M (cortex) and 5.3 × 10^-8M (medulla). CT inhibited cAMP-PDE activity more effectively than cGMP-PDE activity, whereas the inhibition by ADH was vice sera. PTH, angiotensin II, and trichrolomethiazide did not affect these enzyme activities. <BR>The data described here imply that these hormones may control kidney function through cyclic nucleotide metabolism by affecting cAMP-PDE and/or cGMP-PDE activity.