Generation of reactive oxygen species by raphidophycean phytoplankton.

Chattonella marina, a raphidophycean flagellate, is one of the most toxic red tide phytoplankton and causes severe damage to fish farming. Recent studies demonstrated that Chattonella sp. generates superoxide (O2-), hydrogen peroxide (H2O2), and hydroxyl radicals (.OH), which may be responsible for the toxicity of C. marina. In this study, we found the other raphidophycean flagellates such as Heterosigma akashiwo, Olisthodiscus luteus, and Fibrocapsa japonica also produce O2- and H2O2 under normal growth condition. Among the flagellate species tested, Chattonella has the highest rates of production of O2- and H2O2 as compared on the basis of cell number. This seems to be partly due to differences in their cell sizes, since Chattonella is larger than other flagellate species. The generation of O2- by these flagellate species was also confirmed by a chemiluminescence assay by using 2-methyl-6-(p-methoxyphenyl)-3,7-dihydroimidazo[1,2-a]pyrazin++ +-3-one (MCLA). All these raphidophycean flagellates inhibited the proliferation of a marine bacterium, Vibrio alginolyticus, in a flagellates/bacteria co-culture system, and their toxic effects were suppressed by the addition of superoxide dismutase (SOD) or catalase. Our results suggest that the generation of reactive oxygen species is a common feature of raphidophycean flagellates.

Quantitative analysis of stromal fat content of human parathyroid glands associated with thyroid diseases using computer image analysis.

The stromal fat content in the parathyroid glands and its significance are still controversial. Several methods have also been introduced to evaluate the content in the literature. In an attempt to better understand the significance of stromal fat content, a computer image analyzing system was applied and 62 glands were investigated using routinely processed tissue. Our study revealed that the average stromal fat content was 34.8 +/- 18.7% which was lower than that of other studies. The stromal fat content was correlated with the age, grade of obesity, area of the gland and serum parathormone level; however, no consistent patterns were obtained with other clinical parameters. These results indicate that the change of stromal fat content may be related to the general condition of the patient similar to the change of fat in other organs. However, the decrease of the content may indicate the early change of parathormone secretory activity even if the serum examination shows no evidence of hyperfunction of the glands.

Differential biological significance of tissue-type and urokinase-type plasminogen activator in human breast cancer.

Plasminogen activator (PA) is a serine protease existing in two forms known as tissue-type (t-PA) and urokinase-type (u-PA). To examine whether PA is related to the postoperative clinical course of human breast cancer, total PA activity, t-PA activity, u-PA activity, and immunoreactive t-PA were determined in tissue extracts from 144 breast cancer specimens. The patients were initially divided into four groups according to the postoperative clinical course: Group I (83 patients who are disease-free), Group II (20 patients whose first metastases were found only in bone), Group III (19 patients whose first metastases were found in both bone and lung), and Group IV (22 patients whose first metastases were found only in lung). Total PA activity was significantly lower in Groups, II, III and IV than in Group I. Both t-PA activity and t-PA antigen levels were also significantly lower in Groups II, III and IV than in Group I, while no significant difference was found in u-PA activity among these groups, indicating that low activity of total PA in Groups II, III and IV was due to a decrease in t-PA but not in u-PA. In the multivariate analyses, t-PA activity was found to be an independent prognostic factor for relapse-free survival. When four groups of patients were further analysed in terms of nodal status, both t-PA activity and antigen levels were markedly decreased in the node-negative Group II compared with the node-negative Groups III and IV or with the node-positive Groups II, III and IV. Of additional interest, u-PA activity was significantly higher in node-positive patients than in node-negative patients with any group. The clinico-pathologic analyses of the patients in this series showed that node involvement and lymphatic invasion were more frequently positive in Groups III and IV than in Groups I and II. When 144 breast cancers were categorised in terms of combinations of oestrogen receptor (ER) and progesterone receptor (PgR) status, breast cancers which were positive for both receptors were found to contain the highest t-PA activity and antigen. This study provides provocative evidence suggesting a possible differential significance of t-PA and u-PA expression in human breast cancer.

Branch retinal artery occlusion following thyroidectomy for papillary carcinoma of the thyroid: report of a case.

A rare case of branch retinal artery occlusion (BRAO) following a subtotal thyroidectomy for thyroid cancer in a 58-year-old woman is reported herein. Five days after her thyroidectomy, the patient complained of having had a reduction in visual acuity and visual field loss of the superior nasal side in her right eye since the operation. BRAO was diagnosed following the discovery by funduscopy of inferotemporal branch artery occlusion with retinal edema, hemorrhage, and periarterial sheathing in the right eye. Despite immediately puncturing the anterior camera and massaging the eyeball while administering intravenous anticoagulant therapy, the visual field disturbance remained unchanged. The most common causative factor of postoperative sudden BRAO is reported to be emboli. However, in our case, the most likely cause was the stretching and pressure exerted on the carotid artery with consequent atheromatous plaque formation at the time of thyroidectomy.

[A case of advanced breast cancer with multiple organ metastases successfully treated by tamoxifen].

A 66-year-old postmenopausal woman presented in June 1991 with a giant ulcerated left breast tumor. She had discovered the tumor two years previously, but had never visited any medical institution. She was diagnosed as advanced breast cancer with multiple lung metastases, bone metastasis, and both supraclavicular lymph node metastases by physical examination, fine needle aspiration cytology, chest X-P, and bone scintigraphy. Incisional biopsy, performed to confirm the histological type of breast cancer and to evaluate estrogen and progesterone receptor (ER and PgR) status, revealed solid-tubular carcinoma. Both ER and PgR were highly positive at 322.6 and 228.0 fmol/mg protein, respectively. Therefore, endocrine therapy was chosen to treat this advanced breast cancer patient, although she had multiple organ metastases. Twenty mg of Tamoxifen a day was administered per os. After treatment with tamoxifen, the size of ulceration started to decreased and the dyspnea caused by multiple lung metastases was reduced. Eight weeks after, she showed partial response (PR) determined from the size of the ulceration and chest X-P. She has been maintaining PR for more than 9 months. Thus, Tamoxifen was shown to be very effective for this case of advanced breast cancer with multiple organ metastases.

[Estrogen dependent plasminogen activator in breast cancer cells; experimental and clinical studies].

Hormonal regulation of plasminogen activator (PA) in rat mammary tumor induced by 7,12-dimethylbenz (a) anthracene (DMBA) was studied both in vivo and in vitro. PA activity in DMBA-tumor was markedly decreased by ovariectomy, and recovered in a dose-dependent fashion upon estradiol administration. This estrogen-stimulated production of the enzyme was prevented by actinomycin D, cycloheximide and tamoxifen. Furthermore DMBA-tumor cells in primary culture displayed similar estrogen-dependency toward the production of the enzyme without any cell proliferation. This indicates that estrogen might regulate de novo synthesis of PA at a transcriptional level via an estrogen receptor system, and that this hormone might support the growth of DMBA-tumor into adjacent tissues by inducing PA in a direct manner via a route distinct from a prolactin pathway. To examine whether PA reflects the functional state of estrogen receptors in human breast cancer, the enzyme activities were determined in extracts prepared from 160 breast cancer specimens and compared on qualitative and quantitative bases with the levels of steroid receptors. The results strongly suggest that PA can be used as an effective functional marker for hormone dependence in human breast cancer.

A new technique of depositing phospholipid bilayers on quartz surfaces: its use in membrane spin-label studies.

We have developed a new improved technique termed the parallel-beam spattering (PBS) method for depositing phospholipid bilayers on quartz surfaces. This technique involves atomizing the phospholipid mixture with a stream of nitrogen gas and passing this atomized mixture through two orifices separated by a distance to achieve a parallel beam of atomized particles before deposition on the quartz plate. A static electric field can easily be applied to the quartz surface. Also a goniometer of new design has been constructed to allow precise positioning of the deposited phospholipid bilayers with reference to the magnetic field. We have utilized the PBS method to deposit phosphatidylcholine/nitroxyl labeled cholestane mixtures on quartz plates and have found that hydrated bilayers of these mixtures yield ESR spectra with essentially the same characteristics as those obtained using more conventional techniques. The distinct advantage of the new technique for depositing bilayers is that there is no spectral anomaly present which usually is present when the more conventional method of depositing bilayers is used. The spectral anomaly is apparently caused by a portion of the bilayers aligned in directions not directly parallel to the quartz surface. For precision work the spectral anomaly is unacceptable. It is not observed with the new PBS method which has yielded highly reproducible results.