The effects of O-acetylsterigmatocystin and related compounds on rat liver and cultured chicken embryonal liver cells.

Fine structural nucleolar changes induced in rat liver and primary tissue culture cells from 10-day-old chicken embryonal liver by O-acetylsterigmatocystin (AcO-stg), related compounds and aflatoxin B1 were compared. (1) Male Wistar rats were given a single i.p. injection of sterigmatocystin (stg), AcO-stg, and aflatoxin B1. 3 days after the injection of 15 mg/kg of stg, sporadic single cell necrosis was observed in rat liver, whereas rats treated with 8 mg/kg AcO-stg or more, and 3 mg/kg of aflatoxin B1 showed massive liver necrosis. Acetylation resulted in a marked increase in solubility in polar organic solvents. This increased solubility could play an important role in determining toxicity. (II) Treatment with the compounds with an unsaturateddelta1,2-furobenzofuranring system, such as AcO-stg, demethyl-diacetyl-stg (deMe-diAc-stg), and aflatoxin B1, resulted in nucleolar segregation and fragmentation of primary culture cells. Both parenchymal and mesenchymal cells in culture were susceptible to AcO-stg and deMe-diAc-stg, while the mesenchymal cells were more resistant to aflatoxin B1 than the hepatocytes. The inhibition of RNA synthesis in both cell types as determined in radioautography was in accordance with the electron-microscopic observations. Acetyldihydrosterigmatocystin (AcO-dihyd-stg), a saturated delta1,2-furobenzofuranring compound, was less toxic to primary tissue culture cells.     

Studies on nucleoli in rosetting T and B lymphocytes of the human peripheral blood

The incidence of various nucleolar types was studied in human rosetting lymphocytes to provide an information on nucleolar types present in T and B lymphocytes of the peripheral blood. The results clearly demonstrate that both T and B lymphocytes of the peripheral blood mostly contain ring shaped nucleoli ("resting nucleoli") and less frequently other nucleolar types such as nucleoli with nucleolonemata or compact nucleoli ("active nucleoli") and micronucleoli ("inactive nucleoli"). Since all known nucleolar types and particularly micronucleoli may be observed in both T and B lymphocytes, nucleoli in these cells cannot indicate the type or origin of these cells but simply the state of the nucleolar RNA synthesis.     

Sequential Pathology of Experimental Aflatoxicosis in Quail and the Effect of Selenium Supplementation in Modifying the Disease Process

Feeding of aflatoxin B1 @ 1 ppm to 2-week old Japanese quail for a period of 8 weeks produced gross and microscopic changes in the liver, skeletal muscles, heart and bursa of Fabricius. These included fatty changes, bile duct hyperplasia and lymphoid aggregation in liver; haemorrhages in thigh, breast muscles and myocardium; mild depletion of lymphocytes, cystic degeneration and fibrous tissue proliferation in bursa of Fabricius. More or less similar lesions were seen in quail chicks fed on aflatoxin with sodium selenite @ 5 ppm but these were of lesser intensity and appeared at later stages of the experiment thereby indicating that supplementation of selenium had some protective action against the toxic effect of aflatoxin B1 in Japanese quail.     

Ultrastructure of cells of rat lymphatic organs during continuous irradiation

Changes in the ultrastructures of lymphatic organs of rats observed from the 2nd to 22nd day following continuous irradiation with gamma rays at a daily dose of 115 mGy (exposition: 12 R/day) are described. The maximum of destructive changes in lymphocytes was observed on the 11th to the 14th day of irradiation. A gradual balance between dystrophic and regenerative processes was achieved on the 18th day. In this connection to correlation could be determined between the ultrastructural changes described and the fluctuations of lymphocyte numbers in the lymphatic organs and peripheral blood during continuous irradiation.     

In vitro microsome-mediated aflatoxin B1-DNA binding and its inhibition by cytosol of various organs of the hamster and quail

We studied thein vitro activation of aflatoxin B1 (B1) by microsomes and its inactivation by the cytosol of various quail and hamster organs, using B1-DNA binding as an index. The microsomal activity of the liver to bind B1 to DNA was not largely different between the two species and was higher than that of the other organs examined in either species. The microsomal activity of the kidney and lung was very low in the quail compared with the hamster, indicating the very small contribution of the lung and kidney microsomes to the activation of B1 in birds. Only the hamster liver cytosol showed strong inhibition of microsome-mediated B1-DNA binding.     

Acute and subchronic toxicity of aflatoxin B1 to rohu, Labeo rohita (Hamilton)

Pathological alterations in various organs of rohu (L. rohita) fingerlings following acute (0, 7.50, 11.25 and 13.75 mg/kg body weight) and subchronic (0, 1.25 and 2.50 mg/kg body weight) single i.p. aflatoxin B1 exposure for 10 and 90 days, respectively, were investigated. Mortality (dose-dependent) was marked only during acute toxicosis. The changes observed in various organs were dose and time dependent. The acute dose groups revealed toxic changes viz., necrotic and vascular changes in liver and gill lamellae; meningitis, congestion in brain, degeneration and inflammatory reaction in heart along with degenerative to necrotic changes in kidney tubules and sloughing of the intestinal mucosa. During subchronic exposure to this toxin, preneoplastic lesions in liver along with changes in spleen, intestine, gill and pancreas were recorded. With low doses of aflatoxin, the fish did not reveal any mortality or external signs other than catchexia and increased pigmentation on scales. In composite culture practice of Indian major carps, this could be of economic significance.     

Effect of continuous irradiation on the thrombopoietic system in mice

In this paper the changes of the megakaryocyte number of the spleen and those of thrombocyte number of the peripheral blood were studied during continuous irradiation with a dose rate of 9.57 to 957 mGy/day. Beginning with a dose rate of 95.7 mGy/day the thrombocyte number of the blood and the megakaryocyte number of the spleen of irradiated animals decreased significantly. Whereas the thrombocyte number remained permanently decreased, the cell number of the megakaryocyte type is increased temporarily to a clearly higher level as compared with the controls on the 100th day of irradiation approximately. This is especially true for the middle dose rate. During this time of irradiation nucleolar hyperchromatosis as well as pycnosis were observed in many megakaryocytes.     

The development of lymphoid and haemopoietic tissues in pig fetuses

This paper presents the results of the development of lymphatic and haemopoietic organs in pig fetuses of various ages. The thymus appears to be the first lymphatic organ in these fetuses as well as in other animal species so far studied. On the 77th day the thymus is fully morphologically developed. The accumulations of lymphocytes in the spleen appear on the 70th day. The development of periarteriolar formations takes place around the 84th day of gestation. Further development of lymphoid tissue in the lymph nodes, tongue (tonsilla lingualis) and intenstine is described. Lymphatic follicles were observed both in the tongue and the small intestine on the 77th day. The dynamics of haemopoietic activity in the liver and bone marrow is characterized. The germinal centers in lymphoid folicles were never observed as well as cells of the plasmatic series.     

Quantitative studies of haematological values in long-term ovariectomized, ovariohysterectomized and hysterectomized rats

The effects of ovariectomy, ovariohysterectomy and hysterectomy on total and differential white blood cell counts, distribution of T and B lymphocytes and T/B cell relationship were studied. Changes in these parameters associated with the surgical operations were observed in total leukocytes and lymphocytes, absolute and relative band neutrophils and T/B cell relationship. Results suggest that the ovaries together with the uterus are potential regulatory organs upon the absolute number of circulating leukocytes and lymphocytes in female Lewis rats. In addition to their effects upon this important population of cells, the ovaries and uterus have moderate effects upon relative T and B lymphocyte numbers in peripheral blood. In general the changes depend mainly on the removal of the ovaries and to a lesser degree on hysterectomy.     

Toxoplasma gondii: Effect of maternal infection in the development of lymphoid organs of BALB/c neonates

Toxoplasmosis is one of the worldwide parasitic zoonoses. Alterations in the lymphopoietic system are still poorly studied. We analyzed lymphoid organs of BALB/c mice neonates from Toxoplasma gondii-intraperitoneally-infected mothers on 19th day of gestation, with 30 tachyzoites of strain RH. Normal non-infected pregnant females were used as controls. At 7 days after birth, animals were classified as neonates from infected (NIM) and neonates from non-infected mothers (NNIM). Weight of the thymus and number of thymic cells in NIM were decreased, percentage of apoptosis was significantly increased. Decrease in lymphocytes and monocytes and an increase of plasma cells were observed in bone marrow of NIM. Peripheral blood of NIM showed an increase of monocytes and neutrophils and a decrease in lymphocytes. Infection of the mother during the last day of gestation provokes in the neonates changes in the lymphoid organs that could explain survival of 75% of them.     

瘟病病毒感染对三角帆蚌主要消化器官的影响

通过人工感染实验,在感染三角帆蚌瘟病病料组织后第3、5、7、9、11 d,运用光学显微镜和电子显微镜分别观察了三角帆蚌(Hyriopsis cumingii)主要消化器官的病理变化特征.结果表明,三角帆蚌瘟病病毒(H.cumingii Plague Virus,HcPV)严重破坏了三角帆蚌消化器官的结构.主要消化腺肝损伤最为严重:光镜下,攻毒7 d内腺管肿大,管腔缩小,7 d后腺管细胞空泡化并形成多核体;电镜下,线粒体、内质网等细胞器结构破坏,病毒粒子增殖速度快.消化道的病理变化主要表现为胃、肠结构的破坏,胃肠基本结构及感染病毒后的病理变化相似:光镜下,攻毒7 d内胃肠结构变化不大,7 d后柱状细胞肿大,纤毛脱落,并伴有上皮细胞的脱落;电镜下,细胞器结构破坏,甚至空泡化,病毒粒子前期增殖较慢,后期增殖较快,但总体增殖速度比肝慢.     

Some studies of the effects of aflatoxin B1 in vivo and in vitro on nucleic acid synthesis in rat and mouse.

The mouse compared with the rat, is more resistent to the acute toxic action of aflatoxin B1 and is refractory to its hepatocarcinogenic properties. Aflatoxin B1 inhibits DNA synthesis more strongly than RNA synthesis in the rat, and both nucleic acid syntheses more strongly in rat than in the mouse. Mouse hepatic microsomes, like those of the rat, are capable of metabolizing aflatoxin B1 in vitro in the presence of NADPH, to an active form which binds to DNA both in solution and in intact nuclei and also inhibits nuclear RNA synthesis. Non NADPH-dependent binding of aflatoxin B1 to nuclei is not effective in inhibiting RNA polymerase and is largely removed by washing with lipid solvents. Mouse nuclear RNA polymerases particularly Mn 2+ (NH4)2SO4 primed acitivity are more resistant to inhibition in vitro by activated aflatoxin B1 than are the corresponding enzyme activities in rat liver nuclei. This would appear to be due to the bound aflatoxin B1 being less efficient in the case of the mouse nucleus, in inhibiting RNA synthesis. Mouse liver slices exhibit a much lesser degree of inhibition of RNA synthesis by aflatoxin B1 than do rat liver slices. Accompanying this is a lower level of binding of aflatoxin B1 to subcellular particulate fractions in the mouse liver slice compared to the rat, this disparity being most marked in the case of the nuclear fraction. The suggestion is made that the resistance of RNA synthesis in the mouse liver, to aflatoxin B1, and perhaps also resistance to its toxicity, is dependent, not on a lower capacity to activate the toxin, but (a) on a less efficient inhibition of RNA synthesis by nuclear bound toxin, and (b) a detoxifying mechanism at least partially situated in the cytosol fraction.     

Tissue Distribution and Metabolism of Aflatoxin B1-14C in Broiler Chickens

The effects of administering low levels of aflatoxin B(1)-(14)C by crop intubation daily for 14 days to broiler chickens were determined. Studies on the distribution of (14)C in the blood, selected organs, tissues, and excreta were conducted. No toxic effects were observed in broiler chickens during the 14 days of the experiment. The broiler chickens excreted 90.64% of the (14)C administered. Of the (14)C retained, 11.04, 9.83, 4.30, 12.52, 31.66, and 30.63% were detected in the blood, liver, heart, gizzard, breast, and leg, respectively. Chemical assay of those samples demonstrating radioactivity revealed that 81.2% of the radioactivity in these substrates was not extractable by classical extraction procedures while approximately 10% was extractable. Treatment of aqueous extracts for conjugated steroids by treatments with beta-glucuronidase revealed that 31.5% of the (14)C detected in the aqueous extract was a liberated glucuronide conjugate of aflatoxin M(1)-(14)C.     

Ultrastructural changes in murine lymphocytes induced by aflatoxin B1

This investigation sought to determine whether splenic lymphocytes obtained from Balb/C mice exposed to aflatoxin B1 (AFB1) showed any ultrastructural changes which could account for the immunodysfunction attributable to aflatoxins. Lymphocytes obtained from Balb/C mice administered aflatoxin B1 in olive oil daily for three weeks were studied using both transmission and scanning electron microscopy. The lymphocytes demonstrated ultrastructural changes primarily in the mitochondria where marked internal dissociation of the cristae was revealed by transmission electron microscopy. All other cellular organelles were unaffected. No significant alterations in external structure were observed under scanning electron microscopy. The findings of this study indicate that AFB1 administration does not affect the surface topography of lymphocytes, but AFB1, by causing extensive mitochondrial damage, may affect the way in which these cells function. This could be a possible explanation for the immunodysfunction associated with AFB1.Abbreviations AFB1 Aflatoxin B1 - SEM scanning electron microscopy - TEM transmission electron microscopy     

Selenium chemoprevention of liver cancer in animals and possible human applications

An inverse correlation between geographic distribution of liver cancer incidence and the selenium (Se) contents of whole blood and grains was observed in Qidong county, Jiangsu province, a high liver cancer area of the People’s Republic of China. Animal experiments demonstrated that supplementation of Se reduced the incidence of liver cancer in rats exposed to aflatoxin B₁. Se was also shown to inhibit the growth of transplanted tumors. A lower incidence of liver preneoplastic alterations and reduction of hepatitis B virus infection in ducks by Se-supplementation was observed, and three pilot studies for a Se-intervention trial on human liver cancer were carried out on the residents of Qidong county. A protective effect on the cellular DNA damage induced by aflatoxin B₁ was observed in lympocytes from human with Se-supplements.     

鳜鱼头肾的组织发生及成鱼头肾B淋巴细胞的分布

通过整体连续切片,研究了鳜鱼不同发育时期的头肾结构,并利用原位PCR方法检测了B淋巴细胞在鳜鱼头肾中的分布。在孵化后第1d观察到了肾组织,主要由肾小管组成。尔后头肾的发育经历了三个结构和功能的转变。第一个阶段为孵化后第1d到第7d,头肾作为滤过性器官存在,由肾小管及少量淋巴细胞组成。第二个阶段从第8d到第36d,是一个功能混合型阶段,头肾中既有肾小管,又有造血组织;随时间推移,肾小管数量减少,淋巴细胞数量剧增。紧接着进入第三个阶段：肾小管完全消失,头肾中开始出现大量的嗜铬细胞,头肾作为淋巴-肾上腺组织而存在。肾上腺首先出现在头肾前端,随发育成熟,集中分布于头肾门静脉周围。IgM在鳜头肾中大量表达,IgM分泌细胞分布于整个头肾组织,在血管周围有集中趋势[动物学报51(3)：440—446,20051。     

A comparative study of the effects of aflatoxin B1, alpha-amanitin and actinomycin-D on RNA synthesis by rat liver.

The effect of different combinations of aflatoxin B1, alpha-amanitin and actinomycin-D on the incorporation of orotic acid-6-14C into RNA was investigated using rat liver slices. The results support the view that the mode of action of aflatoxin B1 and alpha-amanitin are similar in some respects, and that aflatoxin B1 and actinomycin-D act according to different mechanisms. Evidence was also obtained about the formation of an active metabolite of aflatoxin B1 in this system.     

Early ontogeny of monocytes and macrophages in the pig

Prenatal development of cord blood monocytes and tissue macrophages was studied in pig foetuses by immunophenotyping and functional assays. The function of peripheral blood monocytes was compared in germ-free and conventional piglets. First macrophages were identified by electron microscopy in foetal liver on the 25th day of gestation. Monoclonal antibodies against porcine CD45 and SWC3 antigens were used for flow cytometric identification of myelomonocytic cells in cell suspensions prepared from the yolk sac, foetal liver, spleen and cord blood. Leukocytes expressing the common myelomonocytic antigen SWC3 were found in all organs studied since the earliest stages of development. Opsonized zymosan ingestion assay was used to determine the phagocytic capacity of foetal mononuclear phagocytes isolated from cord blood, liver and spleen. In the foetal liver, avid phagocytosis of apoptic cells had been found to occur before cells were able to ingest zymosan in vitro. The first cells capable of ingesting zymosan particles were found on the 40th day of gestation in umbilical blood and 17 days later in foetal spleen and liver. Their relative proportion increased with age. Cord blood monocytes and peripheral blood monocytes in germ-free piglets had low oxidatory burst activity as shown by iodonitrophenyl tetrazolium reduction assay. A remarkable increase of oxidatory burst activity was observed in conventional piglets, probably due to activation of immune mechanisms by the microflora colonizing gastrointestinal tract.