Terumasa Sashikata

Expression of matrix metalloproteinases, tissue inhibitors of metalloproteinase, collagens, and Ki67 antigen in pleural malignant mesothelioma : an immunohistochemical and electron microscopic study

Because matrix metalloproteinases (MMPs) degrade extracellular matrix, including basement membrane, and because tissue inhibitors of MMP (TIMPs) suppress MMP activities, MMPs and TIMPs are considered to play important roles in invasion and metastasis in many malignancies. We examined immunohistochemically the expression of MMPs (MMP-1, -2, -3, -7, and -9), TIMPs (TIMP-1 and -2), and collagens (types I, III, and IV) in 16 patients with pleural malignant mesothelioma (PMM; 8 with the epithelial, 4 with the sarcomatous, and 4 with the biphasic type). Electron microscopy revealed that the tumor cells in all types possessed the characteristics of malignant mesotheliomas, including numerous microvilli and moderate amounts of intermediate filaments. Basement lamina was present only focally. The proliferative Ki67 index was at a high level, compared with values reported in various other malignancies. Positive staining for MMP-1 was observed in most tumor cells in all 16 patients (100%). MMP-2 was expressed in most tumor cells in 2 patients (13%). In contrast, MMP-3, -7, and -9 were not detected in any PMM. TIMP-1 and TIMP-2 were expressed in 3 patients (19%) and 2 patients (13%), respectively. The stromal cells were simultaneously positive for MMPs or TIMPs in the patients whose tumor parenchymal cells were positive for each enzyme. These results indicate that the expression of MMP-1 and MMP-2 may be related to PMM invasion and spread. In particular, as MMP-1 was overexpressed in contrast to the lower expression of TIMP-1, MMP-1 is strongly suggested to play an important role in PMM invasion by degrading the tumor stroma. In spite of general agreement that epithelial-type PMM has a better prognosis than other types, there was no significant difference in the Ki67 index among the histological types of PMM.

Retinoblastoma in a 26-year-old Adult

Retinoblastoma in a 26-year-old woman is reported clinicopathologically, and the difficulties in this clinical diagnosis are presented. Clinical and morphologic findings of this case suggest that rare embryonal retinal cells can persist and be subject to late malignant transformation.

A case of low-grade fibromyxoid sarcoma of the thigh.

A case of low‐grade fibromyxoid sarcoma in the thigh of a 21 year old female is described. The patient had a fist‐sized well‐defined mass in her left thigh that enlarged over a 6 month period. Histologically, the neoplasm showed contrasting fibrous and myxoid areas with a swirling growth pattern. Cellularity was low to moderate, and the stromal cells were benign looking without mitoses or nuclear pleomorphism. The tissue was not noticeably vascular. Some stromal cells were aggregated around the blood vessels. The stromal cells were immunoreactive to vimentin, but were negative to keratin, desrnin, alpha‐smooth muscle actin, actin HHF35, S‐100 protein, neuron‐specific enolase, and epithelial membrane antigen. Ultrastructural examinations of the stromal cells revealed well‐developed rough endoplasmic reticulum, mitochondria, pinocytotic vesicles, and numerous intermediatesized filaments in the cytoplasm. These findings seem to indicate that the stromal cells were fibroblastic in origin. The occurrence of the tumor in a young adult, its location and its large, well defined borders together with the characteristics revealed through histological investigation, indicated that it was in fact what has been termed by Evans as a low‐grade fibrornyxoid sarcoma.

A Case of Epidural Granulocytic Sarcoma Preceding Acute Leukemia

A 20 year‐old male developed both coccygeal and leg pain and followed by rectocystic disturbance. Disc herniation between L5 and S was suspected and laminectomy was performed. At surgery, an easily curretable tumor occupied the epidural space from L5 to the end of the sacrum. In part, the tumor spread out of the vertebral canal and invaded the surrounding muscle tissue. This muscle tissue and part of the lamina were checked histologically. Initial blood analysis revealed 5% blast like cells, but failed to confirm them as leukemic cells. Histologically, the tumor cells had round or oval nuclei with large nucleoli and scanty cytoplasm without granulocytic differentiation. Malignant lymphoma or Ewings sarcoma was initially suspected, but the definite diagnosis was uncertain. Im‐munohistochemical staining with the PAP method and enzyme histochemistry revealed that the tumor cells were positive for lysozyme and naphthol ASD chloroacetate esterase. Thus, granulocytic sarcoma was finally diagnosed. Electron microscopic findings supported this diagnosis. Subsequent karyotyping of bone marrow cells revealed 8; 21 translocation, thus the final diagnosis of this patient was myelodysplastic syndrome, refractory anemia with excess blast cells in transformation or acute myelogenous leukemia, M2, by the FAB classification. Acta Pathol Jpn 40: 922–926, 1990.

Morphogenesis of Dengue-1 Virus in Cultures of a Human Leukemic Leukocyte Line (J-111)

In previous experiments we found that cultures of a human leukemic leukocyte line ( J-111) supported good growth of dengue-1 virus (K. Shiraki and S. Hotta, unpublished data). In this communication we describe results of electron microscopic observations on the infected J-111 cells. Two strains of dengue-1 virus were used: Mouse-passaged Mochizuki strain, and strain 32748 propagated in Aedes albopictus mosquitoes (kindly supplied by Dr. L. Rosen, Pacific Research Section, NIH, Hawaii) (11). The former was in the form of infected mouse brain homogenate, and the latter was of mosquito emulsions

Leiomyosarcoma arising from soft tissue tumor of the mediastinum

 The occurrence of a leiomyosarcoma (LMS) in soft tissue of the mediastinum is rare. We report a 60-year-old woman with an LMS in mediastinal soft tissue who died 8 months after surgical removal. Pathological, immunohistochemical, and electron microscopic features of this rare tumor are described.

Synovial sarcoma arising from the pleura: a case report with ultrastructural and immunohistological studies.

 Synovial sarcoma commonly occurs in the para-articular regions of the extremities, and rarely in the pleura. We report a 46-year-old woman with primary synovial sarcoma of the pleura. She was admitted with a complaint of left-sided chest pain and exertional dyspnea. She had previously undergone two operations for pleural neoplasm, at the ages of 33 and 36 years. A computed tomography scan revealed an expanded mass in the left thoracic cavity, involving the surrounding tissue. Macroscopic findings demonstrated a 25 × 25 × 15-cm grayish-white mass with hemorrhage beneath the pleura. Both epithelial and spindle cells were observed microscopically. Ultrastructural microscopy of the epithelioid cells demonstrated short, blunt microvilli on the luminal surface, and desmosomes between the neoplastic cells. Immunohistochemically, the tumor cells of the epithelial component were positive for embryonal membrane antigen (EMA), carcinoembryonic antigen (CEA), human mesothelial cells (HBME)-1, and cytokeratin, and the spindle cells were positive for vimentin. These findings led us to a diagnosis of primary synovial sarcoma of the pleura. She had no evidence of recurrence or metastasis after the third operation.

Release of Arboviruses from Cells Cultivated with Low Ionic Strength Media

Discussion and Summary The present study indicates that production of CHIK and DEN-1 viruses in BHK-21 cells were inhibited by lowering NaCl concentrations of culture media. The inhibitory effect was reversed rapidly (within 30 sec) by placing the cells in normal medium. By changing the media from normal to low NaCl concentrations, the inhibition of virus release again took place within short periods of time. In this manner, the inhibition of virus release and its recovery could be repeated practically indefinitely in a particular culture. The effect was due to the ionic strength rather than osmolarity of media. No substances other than the salt such as amino acids or culture medium ingredients were regarded to be involved. While the present data are compatible with those previously reported with viruses of Sindbis (3) and polio (2), some unique findings were obtained in our electron microscopic studies. The cells cultured in low ionic strength media did not reveal characteristic pictures of viral budding from the cell surface membrane as commonly seen in cells cultured in normal media. In spite of it, the “precursor particles” (8, 9) were observed in the cells cultured in low ionic strength media as in normally cultured cells. As generally accepted (7-12), the group A arboviruses acquire their outer coat from the cell surface membrane of host cells during the budding stage. The ionic strength seems to influence this process, altering certain biochemical and/or biophysical conditions of the cell membrane structures. This may have a significant relation with the mechanism of virus release from host cells such as observed with Western equine encephalitis virus in chick embryo cells (13) or Venezuelan equine encephalitis virus in KB cells (14).

Amino Acids Requirements for Reproduction of Arboviruses

Discussion and Summary In the present experiments, it was shown that the maturation of CHIK and DEN-1 viruses was markedly suppressed by the deprivation of glutamine and cystine, respectively. The difference of amino acid requirements may reflect a difference in the maturation process of the two kinds of viruses. Evidence have been presented, indicating that the maturation sites of group A and B arboviruses were characteristically different from each other (11, 14). Some details of the mechanism(s) of the phenomena were investigated, especially those dealing with CHIK virus and glutamine. The inhibitory effect of deprivation was reversible; the virus yields were restored by putting the cells from deprived medium into normal medium and vice versa. Such restoration and suppression were particularly clear during the earlier stages of the virus infection. In the radioisotope incorporation experiments, it was shown that the deprivation was not directly related to the viral RNA or protein synthesis in the infected cells. In the electron microscopic examinations, the cells infected with virus and cultured with deprived medium did not reveal the “core particles” inevitably seen in the same cultures fed with normal medium. This finding suggests that the deficiency influences the step(s) prior to the appearance of the core particles. This may be compatible with the above-mentioned data indicating that the reversibility of the deficiency effect was more clearly demonstrated during the earlier stages of the virus infection than in the later stages. It can be postulated therefore that the amino acid deprivation (L-glutamine in the case of CHIK virus) is possibly involved at certain stages for the assembly of viral structures to produce complete virions. Since, however, it was clearly shown that the glutamine did not compensate the low ionic strength effect already described, the viral maturations stages affected by amino acid deficiency and low ionic strength are probably different from each other.