Akihiro Masuda

Lysozyme localization in human gastric and duodenal epithelium

SummaryThe distribution of lysozyme in normal gastric and duodenal mucosa was studied by light- and electronmicroscopic immunocytochemical techniques (direct enzyme-labeled antibody method).In the duodenal mucosa, lysozyme was found in the Paneth cells and the epithelial cells of Brunners glands. Electron-microscopically, lysozyme was found in rough endoplasmic reticulum and perinuclear spaces, which were assumed to be protein-synthesizing organelles, and also in the secretory granules of Paneth cells. Additionally, lysozyme was detected in the stomach in mucinous granules and in some parts of the rough endoplasmic reticulum within the epithelial cells of the pyloric glands, the mucous neck cells of the fundic glands, and in several surface epithelial cells of the plyoric and fundic regions.This suggests that some quantity of lysozyme in gastrointestinal secretion originates from the gastric and duodenal glands, and that it acts as a defense mechanism in the gastrointestinal tract.

Pathological Aspects of Radiofrequency Catheter Ablation of the Canine Atrioventricular Node and Bundle of His

Radiofrequency catheter ablation of the atrioventricular (AV) node or bundle of His was performed in 12 adult mongrel dogs. The aim was to create chronic incomplete AV block (first‐ and second‐degree AV block) and to examine the histopathology of the ablated lesions. However, the late electrophysiological results (2 4 weeks follow up) were various: normal in 2 dogs, mild PR prolongation (< 50%) in 2 dogs, first‐degree AV block (PR prolongation a 50%) in 2 dogs, second degree AV block in 2 dogs, complete AV block in 4 dogs. The maximally ablated area (%) of the atrioventricular conduction system in serial histologic sections from dogs with these conditions was 69%, 75%, 89.5%, 95% and 99.5%, respectively. The number of intact conduction cells at the maximally ablated site varied from 6 to 30 in the four cases of incomplete AV block. The mean ablated volume (%) of either the AV node or penetrating His bundle correlated roughly with the degree of AV block. The ablated lesions were well demarcated and almost replaced by dense fibrous tissue at 4 weeks. Interruption (3 dogs) or thinning (1 dog) of the endocardial elastic lamellae was detected, in association with endocardial thickening (mean 913 μm). Endocardial thrombi were found in 3 dogs (2 fresh, 1 organized). We conclude that radiofrequency catheter ablation does not cause severe complicated lesions. Several possible conditions for creating chronic incomplete AV block are discussed. Acta Pathol Jpn 41: 487–498, 1991.

Immunohistochemical study of low affinity fc receptor for ige in reactive and neoplastic follicles

The distribution of low affinity IgE Fc receptors (FceR2, FceRII) in reactive and neoplastic follicles was studied by an indirect immunoperoxidase method with monoclonal antibody specifically reacting to FceRII (H107). The tissues examined in this study included lymph nodes, extranodal tissues of divergent diseases, and follicular lymphomas. In the germinal centers (GCs) of the lymph follicles. FceRII showed a lace-like pattern irrespective of the distribution of IgE. In general, FceRII was positive only in the light zone and not in the dark zone of GCs. The distribution of FceRII was different from that of DRC1(+) FDC which were FceRII(+) and FceRII(-). FceRII was seen by immunoelectron microscopy on the cell surface of follicular dendritic cells (FDCs). IgE-positive GCs in Kimuras disease and Warthins tumor were intensely positive for FceRII in their entire portion. In IgE-positive GCs, an increased number of FceRII-positive lymphoid GC cells was recognized by immunoelectron microscopic observation. In follicular lymphoma, there were also two types of FDC which were FceRII(+) and FceRII(-). These findings indicated that FceRII on FDCs was closely related to the IgE immune response and also was a marker for functional phase or differentiation of FDCs.

Extensive endothelial replacement by tumor cells in the portal system: an autopsy case of intrahepatic cholangiocarcinoma.

An autopsy case of intrahepatic cholangiocarcinoma (ICC) with a peculiar form of extensive portal invasion is reported here. A 76‐year‐old woman presented with anorexia and abdominal discomfort. A high level of serum carbohydrate antigen 19‐9 and endoscopically detected esophageal varices were found. Obvious mass lesion was not identified on CT scan and no portal blood flow was found. The patient died 6 months after admission. At autopsy multiple irregular shaped tumors in the liver were found. The size of the largest one was 3 × 2 cm. These tumors were well‐differentiated adenocarcinomas with partial mucinous carcinoma morphology. Surprisingly, portal veins contained mucinous fluid and the inner surface was lined with a single layer of tumor cells but not endothelial cells. Invasion of carcinoma into the tissue outside the blood vessels was hardly observed in organs other than the liver. This form of extensive invasion of the tumor, termed intimal carcinoma spreading, caused complete obstruction of the portal system. To our knowledge there has been no report on this type of portal invasion of ICC.

Expression of Peroxisome Proliferators Activated Receptor Gamma in the Heart Tissue of Patients with Arrhythmogenic Right Ventricular Cardiomyopathy

Peroxisome proliferators activated receptor gamma (PPARgamma) is a ligand-activated transcription factor of the nuclear receptor family which regulates cell proliferation, fat metabolism and inflammatory process [1,2]. Recently it has been reported that PPARgamma expressed in the heart tissue with various cardiac diseases [3,4]. Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a heart muscle disease of unknown etiology and may lead severe ventricular arrhythmia [5]. In this study, we investigated whether expression of PPARgamma is augmented in the heart tissue of ARVC.