Yoshito Sadahira

Assessment of Coronary Arterial Thrombus by Optical Coherence Tomography

We analyzed optical coherence tomographic (OCT) characteristics of different types of coronary thrombi that had been confirmed at postmortem histologic examination. We examined 108 coronary arterial segments of 40 consecutive human cadavers. OCT images of red and white thrombi were obtained and the intensity property of these thrombi was analyzed. Red and white thrombi were found in 16 (17%) and 19 (18%) of the 108 arterial segments, respectively. Red thrombi were identified as high-backscattering protrusions inside the lumen of the artery, with signal-free shadowing in the OCT image. White thrombi were identified as low-backscattering projections in the OCT image. There were no significant differences in peak intensity of OCT signal between red and white thrombi (130+/-18 vs 145+/-34, p=0.12). However, the 1/2 attenuation width of the signal intensity curve, which was defined as the distance from peak intensity to its 1/2 intensity, was significantly different between red and white thrombi (324+/-50 vs 183+/- 42 microm, p<0.0001). A cut-off value of 250 microm in the 1/2 width of signal intensity attenuation can differentiate white from red thrombi with a sensitivity of 90% and specificity of 88%. We present the first detailed description of the characteristics of different types of coronary thrombi in OCT images. Optical coherence tomography may allow us not only to estimate plaque morphology but also to distinguish red from white thrombi.

Role of the macrophage in erythropoiesis

Macrophages, which are derived from precursor cells in the bone marrow, differentiate specifically under the influence of the local microenvironment. Resident macrophages in hematopoietic tissues can be distinguished from other stromal cells and monocytes by immunostaining with monoclonal antibody F4/80 and anti‐Forssman glycosphingolipid antibody, respectively. Erythroid colony‐forming units adhere to a resident macrophage and differentiate to erythroblasts in the presence of erythropoietin (EPO), resulting in the formation of an erythroblastic island. Resident macrophages play a supportive role in erythropoiesis, probably by preventing apoptosis of the erythroid precursors via adhesive interaction between very late activation antigen 4 and vascular cell adhesion molecule 1. Herein is proposed a model of erythropoiesis based on cooperative interaction between EPO and resident macrophages.

Assessment of the coronary calcification by optical coherence tomography

AIMS Optical coherence tomography (OCT) can delineate calcified plaque without artefacts. The aim of this study was to evaluate the ability of OCT to quantify calcified plaque in ex vivo human coronary arteries. METHODS AND RESULTS Ninety-one coronary segments from 33 consecutive human cadavers were examined. By intravascular ultrasound (IVUS), 32 superficial calcified plaques, defined as the leading edge of the acoustic shadowing appears within the most shallow 50% of the plaque plus media thickness, were selected and compared with corresponding OCT and histological examinations. The area of calcification was measured by planimetry. IVUS significantly underestimated the area of calcification compared with histological examination (y = 0.39x + 0.14, r = 0.78, p < 0.001). Although OCT slightly underestimated the area of calcification (y = 0.67x + 0.53, r = 0.84, p < 0.001), it showed a better correlation with histological examination than IVUS. CONCLUSIONS Both OCT and IVUS underestimated the area of calcification, but OCT estimates of the area of calcification were more accurate than those estimated by IVUS. Thus, OCT may be a more useful clinical tool to quantify calcified plaque.

Expression of protein gene product 9·5 (PGP9·5)/ubiquitin-C-terminal hydrolase 1 (UCHL-1) in human myeloma cells

The neuron cytoplasmic protein gene product 9·5 (PGP9·5)/ubiquitin‐C‐terminal hydrolase 1 (UCHL‐1) protein is a thiol protease that recognizes and hydrolyzes a peptide bond at the C‐terminal of ubiquitin, and is involved in the processing of ubiquitin precursors and ubiquinated proteins. Although this molecule is known as a specific tissue marker for the neuroendocrine system, many reports have indicated that PGP9·5 is a marker for certain tumour types, such as cancer of the lung, colon, and pancreas. The expression of PGP9·5 in myeloma cells was examined. PGP9·5 seemed to be expressed specifically in myeloma cells as compared with other haematological malignant cells. In addition, in myeloma cells subjected to growth‐factor starvation, the upregulation of PGP9·5 was observed in association with that of p27Kip1, a cyclin‐dependent‐kinase inhibitor, although the upregulation caused by irradiation was milder. In contrast, the hypoxic culture of myeloma cells induced down‐regulation of PGP9·5. These results suggested that PGP9·5 may be a good marker for myeloma among haematological malignancies. In addition, it may indicate certain cellular features of myeloma cells, such as sensitivity to proteasome inhibitors.

Involvement of the Chromosomal Translocation t(11;18) in Some Mucosa-Associated Lymphoid Tissue Lymphomas and Diffuse Large B-Cell Lymphomas of the Ocular AdnexaEvidence from Multiplex Reverse Transcriptase-Polymerase Chain Reaction and Fluorescence In Situ Hybridization on Using Formalin-Fixed, Paraffin-Embedded Specimens

The chromosomal translocation t(11;18) is a unique chromosomal aberration associated with mucosa-associated lymphoid tissue lymphoma. API2 and MALT1 genes have been identified around this translocation. We attempted to find chromosomal abnormalities focusing mainly on the t(11;18) translocation in formalin-fixed, paraffin-embedded tissues of ocular adnexal lymphoproliferative disorders using multiplex reverse transcriptase-polymerase chain reaction and/or two-color interphase fluorescence in situ hybridization. By these methods, the t(11;18) translocation was detected in 1 of 8 patients with reactive lymphoid hyperplasia (13%), 3 of 23 with mucosa-associated lymphoid tissue lymphoma (13%), and 2 of 14 with diffuse large B-cell lymphoma with/without mucosa-associated lymphoid tissue lymphoma (14%). Moreover, we performed fluorescence in situ hybridization analysis to detect any numerical aberration of chromosomes 3, 7, 12, and 18 on some specimens nonselectively. No numerical chromosomal abnormalities were detected in 3 cases of reactive lymphoid hyperplasia, whereas three of four cases of mucosa-associated lymphoid tissue lymphoma and all four cases of diffuse large B-cell lymphoma with/without mucosa-associated lymphoid tissue lymphoma components exhibited one or more abnormalities. These findings indicate a possibility that at least in the ocular adnexa, some diffuse large B-cell lymphomas are derived from mucosa-associated lymphoid tissue lymphomas.

CAPILLARY GROWTH FROM REVERSED RAT AORTIC SEGMENTS CULTURED IN COLLAGEN GEL

The process of angiogenesis from aortic segments turned inside out and embedded in collagen gel was studied. Two to three days after inoculation, fibroblastic cells migrated from both ends of the segments. Later, capillary sprouts also appeared from both ends of the segments but not from the outer surface, even though there was a covering of endothelial cells. If the outer surface was injured, capillaries sometimes appeared at the damaged site. This may suggest that endothelial cells have more affinity for basement membrane than collagen gel and that they migrate only from an injured site. Immuno‐histochemical staining demonstrated factor VHI‐related antigen in the capillary structures but not in the fibroblastic cells. Electron microscopically, capillary lumina were lined with several endothelial cells, and fibroblastic cells had the characteristics of smooth muscle cells. Since these fibroblastic cells have been known to appear under angiogenetic conditions in vivo, they may play an important role in angiogenesis, and the present culture technique may be a useful model for studying this process. ACTA PATHOL JPN 38: 1503∼1512, 1988.

Impaired splenic erythropoiesis in phlebotomized mice injected with CL2MDP-liposome: an experimental model for studying the role of stromal macrophages in erythropoiesis.

Erythropoiesis occurs in the presence of erythropoietin (EPO) without macrophages in vitro. In hematopoietic tissues, however, erythroid cells associate closely with stromal macrophages, forming erythroblastic islands via interactions with adhesion molecules. To elucidate the role of macrophages in erythropoiesis, we selectively abrogated stromal macrophages of splenic red pulp of phlebotomized mice by injection with dichloromethylene diphosphonate encapsulated in multilamellar liposomes (CL2MDP‐liposome). In the spleen, no erythropoietic activity occurred until 5 days after the treatment. Colony assay revealed that the erythropoiesis was suppressed at the level of CFU‐E. The splenic erythropoietic activity gradually developed from day 6 after the treatment, when F4/80+ macrophages began to appear in the red pulp. EPO mRNA was expressed in kidney but not in liver or spleen of phlebotomized mice injected with CL2MDP‐liposome, and the serum EPO concentration in these mice was higher than that in phlebotomized mice. These findings suggest that abrogation of stromal macrophages by injection with CL2MDP‐liposome impairs the splenic microenvironment for erythropoiesis induced by hypoxic stress, and this may be an excellent experimental model for further characterization of the in vivo role of splenic macrophages in erythropoiesis.

Epstein-Barr virus-associated post-transplant primary smooth muscle tumor of the liver: report of an autopsy case.

Epstein‐Barr (EB) virus‐associated primary smooth muscle tumors have been reported in immunosuppressed young patients with acquired immunodeficiency syndrome (AIDS) and young people who have undergone liver transplantation. An autopsy case of EB virus‐associated smooth muscle cell tumor in a 21 year old female who received immunosuppres‐sive therapy following renal transplantation Is repotted. Multiple tumor nodules were present in the liver, but no primary lesion was found in any other organ. Histologically, the nodules were composed of spindle cells, positive for α‐smooth muscle action, which were arranged in fascicles and closely associated with vascular channels, thereby suggesting a vascular smooth muscle cell origin. EB virus infection of the tumor cells was clearly demonstrated by in situ hybridization with an EB virus‐encoded RNA 1 (EBER‐1) probe. The present case illustrates that EB virus infection may play some role in the development of smooth muscle tumors not only in immunocompromised young patients with liver allo‐grafts, but also in those with renal allografts.

CD8+, CD56+ (natural killer-like) T-cell lymphoma involving the small intestine with no evidence of enteropathy: clinicopathology and molecular study of five Japanese patients.

The present study reports five CD8+, CD56+ (natural killer (NK)‐like) T‐cell lymphomas involving the small intestine without evidence of enteropathy, from Japan. Three were intestinal T‐cell lymphoma. The site of origin of the other two was not definitive. Four of five patients underwent emergency operation because of intestinal perforation. The small intestines of these patients had multiple ulcerative lesions with or without demarcated tumors. Histologically, the lymphoma cells were monomorphic or slightly pleomorphic and displayed epitheliotropism of varying degrees. Lymphoma cells of all patients shared the common phenotype: CD3+, CD4−, CD5−, CD8+, CD56+, CD57−, T‐cell intracellular antigen‐1+, granzyme B+. In contrast to nasal/nasal type NK‐cell lymphomas, they had clonal rearrangement of T‐cell receptor(TCR) genes and were negative for EBV‐encoded RNA. Immunohistochemistry and genetics suggested that three cases were of αβT‐cell origin and two cases were of γδT‐cell origin. There was no evidence of enteropathy in any patient. The cases followed a clinically aggressive course with a frequent involvement of lung. According to the classification based on the recent genetic studies of European enteropathy‐type intestinal T‐cell lymphoma (ETL), the present cases could be classified as type 2 ETL.

Sphingosine-1-phosphate inhibits actin nucleation and pseudopodium formation to control cell motility of mouse melanoma cells

Sphingosine‐1‐phosphate (Sph‐1‐P), the initial product of sphingosine (Sph) catabolism, has been reported to inhibit motility of mouse melanoma B16/F1 and other types of cells at very low concentrations (10–100 nM). Sph‐1‐P (100 nM–1 μM) inhibited pseudopodium formation by blocking polymerization and reorganization of actin filaments in newly formed pseudopodia, and reduced F‐actin by ∼ 25% in F1 cells. A pyrene‐labeled actin nucleation assay revealed that Sph‐1‐P (100 nM) inhibits actin nucleation mediated by F1 cell plasma membranes. These results suggest that Sph‐1‐P interacts with molecules associated with actin nucleation to inhibit reorganization of pseudopodium formation and cell motility.