Yasukazu Nishiyama

Histo- and immuno-pathological studies on experimental Mycoplasma synoviae infection of the chicken.

Abstract Mycoplasma synoviae strains WVU 1853 and F 2−c AS were administered intranasally or into the hock-joint of 4-week-old specific pathogen-free chickens. The findings obtained by histopathological and immunofluorescent examinations for 8 weeks after inoculation were collated with clinical, bacteriological and serological data. Chickens inoculated intra-articularly developed acute articular lesions that were not paralleled by the recovery of mycoplasmas; those given strain F 2−c AS intranasally (FN chickens) showed gradual development of chronic articular lesions. Myocardial lesions, including Aschoff body-like granulomas, and glomerulo-nephritis with occasional crescent formation, were observed in all groups. At the 4th week and thereafter, generalized vasculitis was seen, especially in FN chickens. These lesions were associated with atrophy of the cortex of the thymus and of the follicles of the bursa of Fabricius, and also with proliferation of plasma and reticulum cells in peripheral lymphoid tissues. In all groups, granular IgG deposits were observed by the fluorescent antibody technique at the site of vascular and renal lesions. The possibility of M. synoviae infection in chickens as a chronic immune disease is discussed.

Immunological Responses of Hamsters in the Acquired Immune State to Mycoplasma pneumoniae Infection

Protective effects of vaccination of hamsters against Mycoplasma pneumoniae infection, evaluated according to the recovery of mycoplasmas and histopathological changes in the respiratory tract after challenge infection, persisted for at least 6 months after the final vaccination. Serum antibody levels reached a maximum in the second week after the last vaccination and decreased markedly between the first and the third months, but increased again in sera obtained from animals given booster injections. Metabolism‐inhibiting antibodies were detected in bronchial washings of animals showing high resistance obtained by vaccinal or passive immunization. Antiserum transfer was also effective for protection but cell‐mediated immune responses were not demonstrated in any animals up to 6 months after the vaccination. Even after 10 months, suppression of both mycoplasmal proliferation and lung lesions was apparent, and a single dose of the vaccine induced a significant booster effect. These findings suggest that (1) humoral immunity is more important than cell‐mediated immunity in resistance of hamsters to M. pneumoniae pneumonia, and (2) the antibody secreted in the respiratory tract may be involved in the local defense mechanisms.

Effects of thymectomy and bursectomy on the systemic lesions of experimental Mycoplasma synoviae infection of the chicken

Abstract The development of the systemic lesions of Mycoplasma synoviae infection was examined histo- and immuno-pathologically 2 and 4 weeks after the intraarticular inoculation of strain WVU 1853 in previously thymectomized or bursectomized and concomitantly X-irradiated (STx-X and SBx-X, respectively) chickens. The articular lesions in STx-X chickens showed chronic inflammatory changes 2 weeks after inoculation. In addition, in STx-X chickens, granular IgG deposition was detected at the sites of generalized vasculitis and glomerulonephritis by the fluorescent antibody technique. The bursa of Fabricius was atrophic and hyperplasia of plasma cells was observed in the thymus-dependent areas and red pulp of the spleen. The SBx-X chickens, on the other hand, showed acute inflammatory changes in articular tissues and no vasculitis or glomerulonephritis. These results suggest that M. synoviae infection in chickens could lead to an immune complex disease by impairment of the immune mechanism, presumably initiated by thymic dysfunction.

Role of Humoral Antibodies in Resistance to Mycoplasma pneumoniae Pneumonia in Hamsters

Golden Syrian hamsters adoptively immunized with hyperimmune Mycoplasma pneumoniae rabbit antiserum, immunoglobulin (Ig) M‐rich (IgM) fraction, IgG‐rich (IgG) fraction, antiserum absorbed with either killed M. pneumoniae or killed Staphylococcus aureus organisms, or antiserum treated with 2‐mercaptoethanol (2‐ME) were examined for resistance against aerosol infection with virulent M. pneumoniae. Significant resistance to the establishment of infection in the respiratory tract was shown in hamsters pretreated with the untreated antiserum, IgG fraction or 2‐ME‐treated antiserum, whereas animals pretreated with the IgM fraction and the antisera absorbed with M. pneumoniae or S. aureus organisms were not significantly resistant. Histopathologically, lung lesions were markedly suppressed in animals with high resistance, but were typically pneumonic in animals with low or no resistance. The efficacy of adoptively administered serum preparations was closely related to their antibody titers. The results indicate that humoral antibody plays an important role in protection against experimental M. pneumoniae pneumonia in hamsters, although the participation of the cell‐mediated immune response was not determined.

An ultrastructural study on ischemic lesions in rabbits' hearts with pressure overload and hyperlipidemia☆

The effect of hypertension, hyperlipidemia, and the combination of both on acute and chronic myocardial ischemia were evaluated in a total of 30 male rabbits. After preliminary hypertension and/or hyperlipidemic load by loading of the abdominal aorta and/or cholesterol feeding, acute ischemia was produced by clipping of the left coronary artery. The banding produced elevation of carotid arterial pressure and left ventricular hypertrophy. Cholesterol feeding resulted in severe atheromatous changes in all sizes of coronary arteries. The intimal thickening was due to foam cell accumulation in all arteries examined. Animals pretreated with the combination of hypertension and hyperlipidemia displayed the most severe cardiolmegaly with advanced coronary atherosclerosis and chronic ischemic lesions of the myocardium, i.e., perivascular patchy fibrosis in the subendocardial area. Furthermore, electron microscopic detection of ultrastructural myocardial damage, involving glycogen depletion, sarcoplasmic edema, mitochondrial swelling, and contractile abnormalities, was also most frequent in this group. These changes were quantitated using the ischemic score. These results confirm the hypothesis that fatal ischemic injuries may occur clinically in human hearts with coronary insufficiency due to coexistence of hypertensive cardiomegaly and severe coronary atherosclerosis. They offer a model for further study of these combined effects.

Characterization of transmural and subendocardial infarction by typing and grading of ischemic lesions in autopsied human hearts.

Two types of myocardial infarction, transmural and subendocardial, were macroscopically examined, and the gross and microscopic findings were correlated. The transmural type usually consisted of yellowish brown coagulation necrosis in the center of an infarcted focus and coagulative myocytolysis at the marginal zone. The subendocardial type was characterized by coagulative myocytolysis throughout the entire focus. Wavy fiber and colliquative myocytolysis of non‐specific ischemic lesions were seen only microscopically in both peripheral and subendocardial areas of infarcted foci. Coagulation necrosis was associated with obstructive thrombus formation in 79% of cases as a result of absolute ischemia in the transmural type. Coagulative myocytolysis was associated with obstruction by plaque hemorrhage in 27% of cases, and multivessel disease was frequently encountered in the subendocardial type due to insufficient blood supply. Based on histo‐chemical and immunohistochemical examinations, the ischemic lesions were graded in descending order of coagulation necrosis, coagulative myocytolysis, wavy fiber, and colliquative myocytolysis. The close relation between coagulation necrosis and the transmural type as well as that of coagulative myocytolysis with the subendocardial type suggests two different pathogenetic mechanisms of transmural and subendocardial infarction.

An Angiographic Study of Intracardiac Coronary Arteries from Human Autopsy Hearts: Their Clinicopathologic Significance and Characterization During Transmural Myocardial Infarction

In this study of human autopsy hearts, coronary arteries were divided by morphologic criteria into classes A (branching-type) and B (straight-type) arteries. Infarcted hearts and normal hearts were investigated mainly by means of coronary angiography, as well as by gross and histologic examinations. Transmural myocardial infarction originated in the inner half of the myocardial layer, which was predominantly supplied by class A arteries, followed by gradual extension to the outer layer. The early infarcted focus revealed an angiographically avascular state. This may have been the result of shrinkage of the peripheral branches of class A arteries due to increased extravascular resistance rather than to arteriolar obstruction by small thrombi and/or leukocyte plugs. By contrast, class B arteries remained patent and were almost entirely free from such phenomena. They usually penetrated the infarcted focus to drain into the papillary muscles and trabeculae carnae. As the process of myocardial infarction progressed, various patterns of vascular reactions corresponding to the healing phase were demonstrated by these branches within the infarcted foci. The passive response of class A arteries during acute ischemia characterized the early myocardial lesion. Subsequently, neovascularization from the surviving class B arteries in the infarcted focus occurred as a part of the formation of granulation tissue. Newly formed small arteries from class A arteries also participated in this reaction at the marginal area of the lesion. These well-coordinated vascular reactions revealed in greater detail the initiation and progression of the healing process and were reflective of the clinical prognosis.

Histopathological studies on antitumor effect of sporamycin

SummaryMice that had received transplants of sarcoma-180 followed by treatment with sporamycin were examined histopathologically at periodic intervals. A marked degeneration of tumor cells was observed at an early stage after the administration of sporamycin, but the degeneration subsequently ceased and regrowth of the tumor was seen. Marked infiltration of lymphoid cells, granulation tissue, and fibrosis was seen in the stroma or surrounding tissue of the tumor at a late stage after the administration of sporamycin, and the regression of tumor cells became marked. With a few exceptions the mice were completely cured by about the 40th day.In the peripheral lymphoid tissues, a transitory decrease in the number of cells was observed after the administration of sporamycin, but this was followed by regeneration of the cells, followed by a marked increase in the B cell system. On the other hand, lymphoid cell depletion of the thymus had persisted.Transplantation of intact sarcoma-180 to mice preliminarily inoculated with sporamycin-treated sarcoma-180 cells resulted in inhibition of tumor growth in most of the mice, and qualitatively the same tissue reactions as those in mice cured of sarcoma-180 by sporamycin were seen.The results suggest that enhancement both of antigenicity of the tumor (cells) and of the subsequent immune response of the host by sporamycin may be involved in the cure of the experimental tumor.

Effect of antitumor agents on sarcoma-180 tumor cells transplanted to liver, kidney, and lung.

The survival time of animals, inhibition of the incorporation of thymidine-[6-3H] (3H-TdR) into DNA, and histopathological observation were made after the injection of Mitomycin-C, Bleomycin, cyclophosphamide, Daunomycin, Actinomycin-D, or 5-fluorouracil into mice transplanted with sarcoma-180 to their liver, kidney, and lung. The most prolonged survival time was obtained by the injection with cyclophosphamide and a moderate prolonged survival by Bleomycin and Actinomycin-D. In the case of 5-fluorouracil and Daunomycin, there were extreme variations in the survival time depending on the site of tumor growth. Cyclophosphamide and 5-fluorouracil showed greater and longer lasting inhibition of the incorporation of 3H-TdR into DNA of the tumor tissue, whereas the remaining agents caused transient inhibition on the tumor tissue. Inhibitory ratio and duration of the incorporation of 3H-TdR into DNA of normal site of the tissue of tumor-bearing organ were found to be more increased or almost the same compared with those of the tumor tissue. The most rapid recovery of the incorporation of 3H-TdR into DNA was observed in the small intestine among various organs and tumor in any treatment groups. From the histopathological observation, the degree of tumor cell damage by the agent was almost in agreement with inhibition of the incorporation of 3H-TdR up to 72 hr after the treatment.