Showing papers in "Experimental pathology in 1991"

Apoptosis: Mechanisms and Roles in Pathology

Abstract: Publisher Summary This chapter discusses the mechanisms and roles of apoptosis in pathology. Necrosis differs from apoptosis in structure, mechanism, and sequelae. Structurally, necrotic cells show critically damaged organelles, ruptured plasma membranes, and dispersal of cytoplasmic elements into the extracellular space. The mechanisms are various, but do not depend upon continuing synthetic activity. There is no evidence that specific signaling pathways are involved. There is breakdown of membrane homeostasis and net flow of water into the necrotic cell, whose density falls. Intracellular calcium rises uncontrollably to equilibriate with the millomolar concentrations in the extracellular space. The process results in an acute inflammatory reaction, triggered by complement-activating factors emanating from mitochondria that have escaped from the damaged cell. Alternatively, leukotrienes and other arachidonate chemotaxins can be generated from partially- degraded cell membranes. The arrival of neutrophil polymorphs permits digestion and phagocytosis of the constituents of the necrotic cells, but brings with it the risk of further tissue damage.

Interphase nucleolar organizer regions in cancer cells

Abstract: Publisher Summary This chapter discusses interphase nucleolar organizer regions (NORs) in cancer cells. In situ hybridization experiments have demonstrated that NORs contain the ribosomal genes. NORs are also characterized by the presence of proteins that are selectively stained by silver methods. During interphase, the nucleolus is the only site where both ribosomal genes and silver-stained proteins are located. The evidence now available indicates that the fibrillar components of the nucleolus are the interphase counterpart of metaphase NORs. Recently, interphase NORs have become an object of attention for pathologists because their distribution in the nucleolus has been shown to constitute a useful tool for differentiating, at the optical level, malignant from benign lesions in histological and cytological routine preparations. The chapter provides an overview of recent data about the structural-functional organization of interphase NORs, their importance in tumor pathology, and their relationship with the biological characteristics of cancer cells.

Effects of stress on cytokine production.

Abstract: Physiologic stress results in significant alterations in the release of multiple cytokines. Increased production of interleukin-1 (IL-1) occurs following hemorrhage and thermal injury. Hemorrhage, accidental trauma and burns are followed by decreased interleukin-2 (IL-2) generation. Production of interleukin-3 (IL-3) and interleukin-5 (IL-5) is diminished following hemorrhage. Gamma-interferon release appears to be increased following hemorrhage. Stress secondary to infection is accompanied by marked elevations in serum levels of tumor necrosis factor (TNF), which contribute to hypotension and physiologic instability in this setting. Alterations in cytokine release probably play important roles in mediating alterations in immunologic, hemodynamic and cardiorespiratory function known to occur following physiologic stress. The production of all cytokines so far examined is altered by stress. Increased generation of IL-1, and probably of TNF and IL-6, contributes to the acute-phase reaction and hypermetabolic response which accompanies injury, burns, hemorrhage, and overwhelming infection. Severe immunosuppression, involving both T and B cell function, and contributing to the increased incidence of infection after injury may result, at least in part, from the multiple actions of stress-induced alterations in interleukin release. T cell activation is clearly affected by injury-induced decreases in IL-2, IL-3, and IFN-gamma release. Similarly, the depressed generation of systemic and mucosal antibodies to bacterial antigens following injury may be affected by alterations in the production of cytokines affecting B cell function, namely IL-1, IL-2, IL-3, IL-5 and IFN-gamma.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain changes in experimental chronic hypoxia.

Abstract: A model of normobaric hypoxia was developed in which adult female cats were exposed to decreasing amounts of oxygen (21, 15, 10, 8, 7, and 5 vol.%) over a period of 320 days. Blood flow as well as the blood flow responses to changes of pCO2 were depressed in both cerebrum and cerebellum. These decreases were more severe in the cerebellum. The metabolic rate for oxygen was also depressed. A decrease in the Purkinje cell number was evident. A different degree of damage was observed in the top, the intermediate and the bottom region of the cerebellar gyri. Microvascular proliferation occurred in the whole brain.

Carcinogenesis studies with iron oxides

Abstract: Seven different types of iron oxide were examined for carcinogenic properties in intratracheal instillation and intraperitoneal injection tests on rats, which represent particularly sensitive methods for local carcinogenic effects. The total doses lay in the range of maximum tolerance (390/1,530 mg/kg i.t. or 600 mg/kg i.p.). With one exception, at least 50 male and 50 female Sprague-Dawley rats were used per test group, control group and route of administration. Two iron oxides were additionally instilled intratracheally in combination with benzo[a]pyrene. No carcinogenic effect could be demonstrated for the test iron oxides RBW 07105/SV2 (fibrous, magnetic, surface doped with 1.85% cobalt), development product Bayferrox AC 5100 M (fibrous, magnetic, bulk doped with 2.1% cobalt), Bayferrox 1352 (fibrous alpha-Fe2O3), Bayferrox 920 (fibrous alpha-FeOOH), Bayferrox 130 (cubic alpha-Fe2O3), Bayferrox 306 (cubic Fe3O4), or Brazilian iron ore AC 5031 N (alpha-Fe2O3).

Leptospiral antigens (L. interrogans serogroup ictero-haemorrhagiae) in the kidney of experimentally infected guinea pigs and their relation to the pathogenesis of the renal injury.

Abstract: Summary The search for leptospiral antigens ( L. interrogans serogroup icterohaemorrhagiae ) was carried out in 24 guinea pigs experimentally inoculated with 1 ml of culture containing 10 7 -10 8 leprospires and sequentially sacrificed from the first until the 6th day of infection. Semiquantitative analysis of histopathological variables comprising kidney interstitium, tubules and glomeruli was done in 1 μm sections of tissue embedded in glycolmetacrylate. Leptospiral antigen (LAg) and its glycolipoprotein (GLP) expression were detected through PAP in paraffin embedded tissue. The mild interstitial involvement of the kidney, manifested chiefly by oedema and focal interstitial nephritis seen at the 4th day, progressed to tubular damage at the 6th day, characterized by either swelling or cytoplasmic acidophilia of epithelial cells with loss of cell cohesion and sloughing of cells into the tubular lumina. Brush border alterations and mitochondrial changes were observed. Endothelial cell injury was noted in the interstitial vessels. LAg expression was parallel to the kidney changes: small deposits of elongated forms of LAg were detected at the 4th day either within the vascular lumen or free in the interstitium. A rise in the antigen expression was observed at the 5th day when it was seen either around tubules or in their walls. LAg was detected inside the tubular lumina at the 6th day of infection when granular LAg and GLP were abundant. This sequence reproduces the pathway of leptospires in the kidney and the crescent amounts of antigens detected toward the end of the experiment, with antigen concentration in cases of major tissue damage suggesting a direct action of the microorganisms and/or their products in the pathogenesis of the lesions.

Antineutrophil cytoplasmic autoantibodies: disease associations, molecular biology, and pathophysiology.

Abstract: Publisher Summary This chapter discusses antineutrophil cytoplasmic autoantibodies (ANCAs). ANCAs are found in the circulation of patients with necrotizing inflammatory injury to vessels. ANCAs have specificity for proteins in the cytoplasmic granules of neutrophils and the lysosomes of monocytes. There are multiple ANCA types with different specificities, for example, ANCAs specific for myeloperoxidase and ANCAs specific for proteinase 3. The most commonly used method for detecting ANCAs is indirect immunofluorescence microscopy using alcohol-fixed neutrophils as substrate, although enzyme-linked immunosorbent assays using neutrophil subcellular fractions or purified proteins are also used. Two major patterns of ANCA staining are observed by immunofluorescence microscopy. ANCAs specific for granule proteins that remain in granules after alcohol fixation produce cytoplasmic neutrophil staining, whereas ANCAs specific for granule proteins that diffuse from granules and artifactually bind to nuclei after alcohol fixation produce perinuclear staining.

On the question of a carcinogenic action of cobaltcontaining compounds

Abstract: After subcutaneous injections of doses of 5 x 2 and 1 x 10 mg cobalt (II) oxide/kg/week (total dose 1,000 mg/kg), respectively 5 out of 10 and 4 out of 10 rats in a lifetime study developed local malignant tumours (controls 0/10). After intraperitoneal injections of 3 x 200 mg cobalt (II) oxide/kg 14 out of 20 rats developed malignant intraperitoneal tumours (controls 1/20). With a Co/Al/Cr spinel the same treatment produced malignant intraperitoneal tumours in only 2 out of 20 rats. After intratracheal instillation of cobalt (II) oxide in single doses of 2 mg/kg (total dose 78 mg/kg) and 10 mg/kg (total dose 390 mg/kg) there were 2 benign pulmonary tumours among 100 rats in the low-dose group and 2 benign and 4 malignant pulmonary tumours among 100 rats in among 100 rats in the high-dose group. The Co/Al/Cr spinel was tested intratracheally only in the high dose (total dose 390 mg/kg); among the 100 rats this produced 3 malignant pulmonary tumours. Alternating intratracheal instillation of cobalt (II) oxide (total dose 470 mg/kg) and benzo[a]pyrene (total dose 200 mg/kg) led to 9 malignant pulmonary tumours in 20 rats, whereas benzo[a]pyrene alone caused only 1 malignant pulmonary tumour in 20 rats. The results suggest that cobalt (II) oxide (76.7% Co) has a weakly carcinogenic effect. The Co/Al/Cr spinel investigated is still less active, and even in very sensitive tests (i.p. and i.t. administration) shows no statistically significant carcinogenic effect. This smaller effect may possibly be explained by its lower cobalt content (24.0%) or its much lower solubility (only less than 10% of the solubility of CoO in 0.1 n HCl).

Induced hypertension as an approach to treating acute cerebrovascular ischaemia: possibilities and limitations.

Abstract: Summary As, after an stroke, the autoregulation of the cerebral vessels in the ischaemic region is disturbed to a high degree, it is, on principle, possible to improve the blood flow particularly in the zone surrounding the infarct (penumbra) by raising the systemic blood pressure. During a basic treatment with low-molecular dextrans (infukoll M40), 37 patients with an acute ischaemic cerebral stroke multiply underwent elevations in blood pressure up to systolic values of about 210 to 220 mmHg. A comparison with a control group (n = 44) who were treated with low-molecular dextrans revealed no differences in lethality on the 21st day after the stroke. However, a very good acute effect in terms of a short-term improvement was remarkable a result that is noteworthy also in future.

Interactions between endothelial cells and the cells of the immune system.

Abstract: Publisher Summary This chapter reviews the interactions between endothelial cells and the cells of the immune system. Lymphocytes are motile cells, migrating from blood into lymphoid organs or sites of inflammation and then back to blood via the lymphatics. This process, known as lymphocyte recirculation, is of critical importance in the functioning of the immune system as it facilitates interactions between antigen-specific clones of lymphocytes and antigen-presenting cells (APCs) in secondary lymphoid organs or sites o f inflammation. Thus, for the immune system to function properly, lymphocytes should adhere to, and then migrate through, the endothelial cells (ECs) of the vasculature. Based on in vitro studies, it has been suggested that vascular ECs can be capable of acting as APCs during the adhesion event. In addition to this direct interaction, it is also clear that the cells of the immune system, both lymphocytes and monocytes/macrophages, interact with ECs in an indirect way, by means of soluble factors known as cytokines.

Lead induced ultrastructural changes in the testis of rats.

Abstract: Summary Oral lead administration (250 ppm lead acetate through drinking water) to weaning male rats for 70 days resulted in the marked accumulation of this metal in blood and testicular tissue. No marked changes were evident in light microscopy. Ultrastructural changes were revealed in the form of vacuolisation of Sertoli cell cytoplasm and increase in the number and size of lysosomes. Some of the vacuoles contained vesicle like structures. Although there was no impairment of spermatogenesis, the changes in the Sertoli cells may lead to changes in spermatogenesis after chronic exposure.

Applications of in situ hybridization.

Abstract: Publisher Summary This chapter discusses applications of in situ hybridization(ISH). Progress in molecular biology has made several techniques for research and diagnosis available even to laboratories not specialized in this field. The basis of all these techniques is the ability of single-stranded nucleic acids, either deoxyribonucleic acid or ribonucleic acid, to hybridize, that is, to form selectively double strands with nucleic acid molecules of complementary sequence. Prior to hybridization, most of these methods, for example, Southern and Northern blot hybridization, require extraction of nucleic acids from tissues, restriction enzyme digestion, gel electrophoresis, and transfer of nucleic acids to membranes. These are very time-consuming procedures requiring special knowledge and facilities. Another serious disadvantage of extractive techniques is that it is usually not possible to attribute a signal to a particular cell type. However, because most tissues represent a heterogeneous rather than a homogeneous assembly of cells, the sole information that a particular nucleic acid sequence is present in a given tissue is often insufficient. A sequence present in only a small proportion of the cells of a given tissue may be detectable by in situ hybridization (ISH), whereas in filter hybridization o f DNA extracted from this tissue, the sequence may be diluted by the total cellular DNA to below the threshold of detection. The introduction o f in situ hybridization was therefore met with interest from pathologists because it provides a synthesis of classical histopathology with modern molecular biological techniques.

The male reproductive organs in experimental Chagas' disease: I. Morphometric study of the vas deferens in the acute phase of the disease

Abstract: Summary Amastigote forms of Trypanosoma cruzi (Bolivia strain) were detected in the sex organs of male mice 15 days after inoculation. The presence of the parasite close to the lumen of the seminiferous tubules and mixed with spermatozoa in the lumen of the epididymal duct suggests the possibility of transmission of Chagas' disease through coitus. Morphological analysis of the vas deferens revealed structural alterations compatible with the early form of chagasic esophagopathy.

Role of brain, pituitary and spleen corticotropin-releasing factor receptors in the stress response.

Abstract: CRF plays a fundamental role in integrating stress-related responses throughout the neuro-immuno-endocrine axis. Its endocrine effects include actions at the pituitary level to stimulate the synthesis and release of POMC-derived peptides. CRF acts within the CNS to integrate the autonomic, behavioral, endocrine and immune responses to stress. Furthermore, recent evidence suggests that CRF may have direct actions on immunocytes to modulate immune function in the periphery. The actions of CRF in CNS, pituitary, and spleen are mediated by specific, high-affinity membrane receptors with similar kinetic and pharmacological properties. CRF receptors in these various tissues are functionally linked to a guanine nucleotide binding protein mediating stimulation of adenylate cyclase activity. Chemical affinity cross-linking studies demonstrated that the molecular weight of the CRF receptor-binding protein is different in central versus peripheral tissues and that the differences observed in molecular weights are due to the microheterogeneity of the carbohydrate moieties on the receptors in the two types of tissues. In autoradiographic studies, CRF receptors were localized in highest densities in anterior and intermediate lobes of the pituitary, and in brain regions involved in cognitive function, in limbic areas involved in emotion and in brain areas regulating autonomic and other stress-related responses. In spleen, CRF binding sites were localized in the macrophage-rich red pulp and marginal zones surrounding the white pulp regions. Studies examining the effects of CRF administration on local cerebral glucose utilization demonstrated differential changes in glucose utilization in brain regions that have been implicated in mediating the effects of CRF in a variety of homeostatic systems and the organism's ability to respond to stress. Overall, these data provide additional evidence for a physiological role for CRF in the brain-endocrine-immune axis and further support the importance of this neuro-peptide in coordinating the response to stress.

The diabetogenic and acidotropic effects of chelators.

Abstract: Diabetogenic and acidotropic effects of dithizone, 8-(p-toluenesulfonylamino)-quinoline and 8-(benzenesulfonylamino)-quinoline were studied in experiments on cats, rabbits, golden hamsters and mice. Selective damage of insulin producing cells, phase glycemic fluctuations and permanent diabetes development were shown to be connected with chelator zinc binding in the lysosome-segregation apparatus of these cells.

Carcinoembryonic proteins produced by Wilms' tumor cells in vitro and in vivo

Abstract: A Wilms' tumor cell line (HFWT) was established after tissue culture of the Wilms' tumor which had developed in the left kidney of a five-month-old boy. The HFWT line has the following cyto-biological characteristics: 1. The cells have a spindle, round or polygonal shape with neoplastic and pleomorphic features that grew in multilayers without contact inhibition. 2. The cells show a stable proliferation, giving 95 passages within 4 years. 3. The chromosomes show a wide aneuploidy distribution, and the modal number was found in diploid range. The stem cells have a normal karyotyping, 46, XY. 4. Heterotransplantation into nude mice can be easily made, and anaplastic Wilms' tumor resembling the original tumor forms. 5. The principal tumor markers produced by the cells in large amounts in the conditioned culture media were carbohydrate antigen 125 (CA 125) and tissue polypeptide antigen (TPA). 6. A good correlation was found between enlargement of the tumor formed by heterotransplantation into nude mice and the levels of CA 125 and TPA in the serum of the nude mouse. No report on the study of tumor markers widely used in clinical treatment of Wilms' tumor has been available to us, but CA 125 and TPA are considered to be useful in the diagnosis and treatment of Wilms' tumor.

Effects of neurotensin on the pituitary-adrenocortical axis of intact and dexamethasone-suppressed rats.

Abstract: A 7-day infusion with neurotensin (NT) (10 µg · kg -1 · day -1 ) stimulated adrenal growth in intact female rats, and raised ACTH blood concentration, without altering corticosterone (B) plasma level and output by adrenal homogenates. For a week dexamethasone (Dx) administration (125 µg · kg -1 - day -1 ) caused a notable adrenal atrophy, a marked lowering of ACTH and B blood concentrations, and a profound depression of B output by adrenal homogenates. NT infusion reversed Dx-induced adrenal atrophy and plasma ACTH-level drop, but not the impairment in adrenal-cortex secretory activity. In vitro studies showed that NT (10 -6 mol/1) significantly reduced basal, but not ACTH-stimulated B release by isolated rat inner adrenocortical cells. These findings suggest that NT exerts a direct inhibitory effect on B production by rat adrenals, while it is able to enhance ACTH secretion and consequently adrenal growth. Moreover, they indicate that NT evokes a striking, and at present unexplained dissociation between structure and function in the adrenal cortex of Dx-suppressed rats.

Immunohistochemical detection of DNA alkylation adducts in rat and hamster liver after treatment with dimethylnitrosamine.

Abstract: Summary Monoclonal and polyclonal antibodies specific for methylation adducts have been applied in an immunohistochemical study of DNA damage in rat and hamster liver following exposure to dimethylnitrosamine. The approach was validated, for frozen and paraffin-embedded sections, by comparison with biochemical data on adduct levels in whole tissues or specific cell populations in the same experimental systems. The potential application of this method to human exposure assessment is discussed.

The effect of D-penicillamine on CCl4-induced experimental liver cirrhosis.

Abstract: The effect of D-penicillamine (Pe) on liver fibrosis-cirrhosis induced by chronic CCl4 and phenobarbital (Pb) administration in Fischer 344 male rats was studied. Morphometric analysis did not reveal a decrease in the amount of connective tissue fibers after Pe-treatment. Compared to the CCl4 and Pb-treated control groups, Pe had no significant effect on the concentrations of hydroxyproline, a parameter of collagen degradation, either; however, it increased the glycosaminoglycan concentrations. Lymphocyte stimulation by Con-A in the Pe-treated groups did not differ from that of the CCl4 and Pb-treated ones. According to our studies, Pe-treatment was ineffective in rats with liver fibrosis-cirrhosis induced by CCl4 and Pb administration. It seems that Pe can be effective only in the cirrhosis types accompanied by a considerable copper accumulation due to suppression of the toxic effects of copper.

Apoptosis in pancreatic allograft rejection —ultrastructural observations*

Abstract: Transplantation of pancreaticoduodenal allografts in the PVG.RT1c----PVG.RT1u high responder rat strain combination led to the evolution of haemorrhagic pancreatic necrosis over a rejection course of 8d. A cellular infiltrate consisting mainly of monocytes and macrophages was detectable in the stroma while acinar cells showed degranulation and a progressive decrease in number. From day 4 on apoptotic bodies could be identified ultrastructurally within the exocrine tissue. Apoptosis during pancreas rejection, previously undescribed, contributes to acinar cell loss after transplantation in this model.

Effects of arginine vasopressin on the pituitary-adrenocortical axis of intact and dexamethasone-suppressed rats.

Abstract: Summary Weekly infusion with arginine vasopressin (AVP) (2 µg · kg -1 · day -1 ) exerted a slight stimulatory effect on the adrenal growth of intact female rats and induced a 2-fold rise in plasma aldosterone concentration (PAC), without apparently affecting corticosterone (B) and ACTH secretions. Weekly dexamethasone (Dx) administration (125 µg · kg -1 · day -1 ) caused a marked adrenal atrophy, a conspicuous suppression of B and ACTH productions, and a 5fold increase in PAC. AVP infusion reversed the Dx-induced adrenal atrophy. It did not counteract the suppression of B and ACTH secretions, nor did it change PAC. These findings suggest that chronic AVP treatment is able to stimulate adrenal growth by a Dx-insensitive mechanism (i.e. independent of any change in ACTH secretion). Conversely, AVP may enhance the steroid secretory capacity only in adrenocortical cells in which the maintenance of the steroidogenic machinery is assured by normal levels of circulating ACTH.

Molecular Biology of Cytokine Effects on Vascular Endothelial Cells

Abstract: Publisher Summary This chapter discusses molecular biology of cytokine effects on vascular endothelial cells. Vascular endothelial cells constitute the luminal surface of the vascular system and play an active role in normal hemostasis and in various pathophysiological responses, such as inflammation, wound healing, selective transfer of substances to and from the circulation, and regulation of vascular tonus. Positioned at the interface between circulating blood and the subendothelial vascular structures, endothelial cells (ECs) mediate the effects of products and signals released from ECs to the vascular wall. For these reasons, functional and structural abnormalities of ECs might contribute significantly to vascular pathology such as thrombosis, atherosclerosis, and vasculitis. The demonstration that hemostasis, inflammation, and immunity involve close interactions between immunocompetent cells and vascular ECs has marked an important advance in understanding the role of ECs. Cytokines, produced by and acting on ECs, are mediators of the complex bidirectional interactions between immunocompetent cells and ECs. Cytokines affect EC function in inflammation, thrombosis, angiogenesis, and immune responses.

Relation of the reticuloendothelial function to endotoxin hepatotoxicity.

Abstract: Summary The present study was undertaken in rats to clarify whether endotoxin hepatotoxicity can be modified by phagocytic activity of the reticuloendothelial system. Pretreatment with cortisone acetate, diethylstilbestrol, methyl palmitate, triolein or gadolinium chloride markedly improved the mortality rate from endotoxemia and prevented the development of focal random coagulative hepatocellular necrosis and the elevation of serum transaminase activities due to endotoxemia. Cortisone acetate, methyl palmitate and gadolinium chloride are the wellknown depressors of reticuloendothelial phagocytic activity: Diethylstilbestrol and triolein are the stimulators. This suggests that phagocytic activity of the reticuloendothelial system does not relate to not only the mortality rate but also the degree of hepatic injury following endotoxemia.

Nephrotoxic effects of diethylene glycol (DEG) in rats.

Abstract: Summary Diethylene glycol (DEG) is a widely used substance with various risks of intoxication. In adult rats influences of DEG on functional parameters are characterized, indicating early signs of nephrotoxicity. A dose dependent proteinuria, an oliguric effect, an increased excretion of free hydrogen ions and a compensated impairment of renal tubular transport processes can be stated (0.25, 0.5 and 0.75 ml DEG/100 g b.m. i.p.). Following a single dose of 0.5 ml DEG/100 g b.m. i.p. the maximally expressed nephrotoxic effect is measurable 4 to 8 days after administration.