Cellular Manifestations Research Articles

The molecular basis for the assembly and modulation of adherens-type junctions

Ultrastructural analyses of cells and tissues over the last several decades have indicated that cells commonly form contacts through specialized membrane domains. The cellular topology and fine structure of such adhesion sites varies considerably, reflecting the highly diverse physiological roles and cellular manifestations of adhesive interactions. In general, two major classes of adhesions may be distinguished, namely cell-matrix and cell-cell contacts. Among these distinct types of cell adhesions may be formed, attaching cells to the various extracellular matrix (ECM) networks on, or within which cells grow. Some of these attachment sites display a characteristic association with cytoskeletal filaments, providing an apparent mechanical linkage between intracellular force-generating systems and the pericellular connective tissue. It has been widely accepted that these contacts and their spatially- and temporallycontrolled reorganization, play cardinal roles in a large number of processes (which are often quite conflicting) such as cell anchorage and locomotion, growth stimulation and growth arrest, etc. Among these cytoskeleton-bound ECM contacts two major types were discerned on morpho

Cellular and Molecular Mechanisms of Cutaneous Aging

There are two major theories of aging: the programmatic theory states that aging is an inherent genetic process, and the stochastic theory states that aging represents random environmental damage. Processes that are associated with cellular damage and aging are the production of free radicals (a process much enhanced after ultraviolet irradiation) and an increasing number of errors during DNA replication. Cellular manifestations of intrinsic aging include decreased life span of cells, decreased responsiveness of cells to growth signals, which may reflect loss of cellular receptors to growth factors, and increased responsiveness to growth inhibitors. All these findings are more pronounced in cells derived from photodamaged skin. Molecular manifestations of intrinsic aging, studied mainly in fibroblasts, are altered membrane composition, adhesion properties, production of extracellular matrix, and activity of the enzyme catalase. Molecular changes as a result of photoaging are less well characterized; published studies mainly target differences in composition of the extracellular dermal matrix.

Antiatherogenic and antiatherosclerotic effects of mushroom extracts revealed in human aortic intima cell culture

AbstractAlcohol and water extracts from 20 edible fungi species belonging to the following genera— Agaricum, Armillaria, Boletus, Collybia, Coriolus, Cortinfrius, Flammulina, Ganoderma, Hirneola, Lentinus, Lyophyilum, Pleurotus, Sarcodon, Tremella, and Tricholoma— were added to primary culture of cells isolated from atherosclerotic lesions of human aorta to ascertain their influence on the major cellular manifestations of atherosclerosis. Thirteen of the 20 tested extracts were antiatherosclerotic in culture, that is, they caused the decrease in the cellular cholesterol level and/or the inhibition of cellular proliferation ([3H]thymidine incorporation). The antiatherogenic (prophylactic) action of mushroom extracts was also tested using cell culture. The extracts were added to the primary culture of normal intimal cells, which had been stimulated by atherogenic serum from coronary heart disease (CHD) patients to undergo atherogenic transformation (increase in total cholesterol and stimulation of proliferation). Ten of the 20 tested extracts displayed antiatherogenic as well as antiatherosclerotic effects. Four mushroom species were chosen for the study of antiatherosclerotic effects in vivo. Cultivation of “atherosclerotic” cells during 24 hr in the presence of serum from healthy subjects who had had mushroom meals resulted in a 21–30% decrease in the cellular cholesterol level. The atherogenic serum obtained from CHD patients after dietary mushroom consumption partly (30–41%) lost its ability to increase the cellular cholesterol content. The current study presents data suggesting that some mushroom species may be useful as dietary supplements in the prevention and therapy of atherosclerosis.

Studies on the allergic and nonallergic nasal inflammation

Nasal lavage after antigenic and nonantigenic nasal stimulation has become an important tool for the study of inflammatory phenomena in the upper airway. Biochemical and cytologic information is relatively easily obtainable, and pharmacologic manipulations can be readily monitored. This article is of several studies aiming toward a more profound understanding of the mechanisms of allergic and nonallergic rhinitis by the use of laboratory-challenge procedures and nasal-lavage techniques. An early and a late reaction are detected clinically in the nose after antigen challenge of allergic individuals. In addition, the sensitivity to antigen significantly increases after the initial challenge, and this phenomenon is not obligatorily linked to the presence of a late-phase reaction (LPR). Inflammatory mediators, mostly mast cell- and/or basophil-derived, are detected in the nasal washes and correlate with the symptomatology in both the early and the late reactions. The allergen-induced LPR is marked by an early influx of eosinophils and, later, basophils and neutrophils. Elevation of major basic protein and histamine, but not prostaglandin D 2, is detected during the LPR, giving evidence of active eosinophil and basophil participation. Systemic steroids can effectively suppress the clinical, biochemic, and cellular manifestations of antigen-induced LPR. Topical steroids have a similar effect but are also capable of suppressing the early reaction to antigen. A nonallergic form of rhinitis can be induced in the laboratory by nasal inhalation of dry air at freezing temperatures in individuals who report sensitivity to cold and windy environments. Early and late reactions are also detectable with this stimulus, and the panel of mediators appears to be identical with that of antigen-induced rhinitis, indicating activation of the same cell type(s). This stimulus, however, appears to act through different mechanisms, since pharmacologic agents that control the allergen response are inactive against cold, dry air (CDA) reactions. Studies on the mechanism of CDA-induced rhinitis have detected elevations in the osmolality of nasal secretions after CDA challenge. This occurs only in CDA-sensitive subjects and not in CDA nonresponders or antigen-challenged allergic individuals. Elevated osmolality correlates with mediator release, suggesting a role of nasal fluid tonicity in mast cell activation. The above pieces of information offer significant insight in the mechanisms of allergic and nonallergic inflammation of the nose and the upper airways. Reconstitution of that information into a persuasive model of the naturally occurring disease and development of new therapeutic modalities will be our tasks in the future.

How does doxorubicin interfere with actin polymerization?

It is well known that doxorubicin (adriamycin), an antibiotic with an antitumoral action, has some undesirable side effects. Among these, the most serious is, undoubtedly, damage to myocardial tissue (progressive cardiomyopathy). We have for some time focused our attention on the effect of this drug on cellular contractile systems and, more specifically, on the process of actin polymerization, which we consider to be an extremely delicate key point for the economy of most cellular motor manifestations. In the present study, using capillary viscometry, spectrofluorometry and electron microscopy, we have shown a negative action of doxorubicin on various important chemical events which contribute to the transformation of G-actin into F-actin. Specifically, we found that the drug mainly acts by reducing the polymer size. A possible action mechanism of the antibiotic is proposed and a plausible correlation among the events described in vitro and those observed in vivo is advanced.

Cellular and vascular manifestations of cell-mediated immunity

The studies reviewed here emphasize both the complexity and the heterogeneity of cell-mediated immunity. In addition to the round cell infiltrate of the classic descriptions, cell-mediated immunity includes reactions that feature many types of inflammatory cells, that exert profound effects on the blood microvasculature, and that initiate extravascular clotting and, possibly, angiogenesis. The common denominator of all of these reactions is a subset or subsets of sensitized T lymphocytes that, on exposure to specific antigen, recruit and collaborate in other ways with one or more populations of circulating bone marrow-derived cells. Although the reactions generally resemble chronic inflammation by virtue of the lymphocytes and monocytes present, cell-mediated immunity may also take the guise of acute or subacute inflammation when neutrophils or eosinophils predominate and an entirely different morphologic pattern when basophils predominate, as in CBH. Tissue mast cells undergo changes (activation, proliferation) that are generally observed at later stages of delayed hypersensitivity, but no convincing evidence has been presented that these cells play an essential role in the elicitation of cell-mediated immunity. The concept that an essential prerequisite for the elicitation of delayed hypersensitivity is the mast cell-dependent generation of microvascular gaps, favoring inflammatory cell diapedesis, is clearly incorrect. First, lymphocytes fail to traverse certain of the vessels that exhibit such gaps (i.e., those of the SCV) in delayed hypersensitivity reactions in humans. Second, there is no diminution in the cellular infiltration associated with cell-mediated immunity reactions in mast cell-deficient mice. Cell-mediated immunity does not consist of an inflammatory cell infiltrate alone. The local microvasculature is rendered hyperpermeable to varying extents, with resulting extravasation of plasma proteins, including fibrinogen. The majority of extravasated fibrinogen is clotted to cross-linked fibrin, presumably as the result of the actions of procoagulants associated with fixed connective tissue cells and perhaps also because of the activity of infiltrating cells, such as monocytes/macrophages. Clotted fibrin forms a water-trapping gel, which accounts for the induration seen in many delayed hypersensitivity reactions. The microvasculature may also be affected in other ways. Endothelial cells may undergo hypertrophy and cell division or, alternatively, may exhibit profound and progressive injury.(ABSTRACT TRUNCATED AT 400 WORDS)

Mutation at I-A beta chain prevents experimental autoimmune myasthenia gravis.

Immune response (Ir) gene(s) at the I-A subregion of the mouse H-2 complex influence susceptibility to experimental autoimmune myasthenia gravis (EAMG). To determine the importance of the Ir gene product, the Ia antigens, in EAMG pathogenesis, we studied the degree of EAMG susceptibility of an I-A mutant strain, the B6.C-H-2bm12 (bm12), and its parent B6/Kh. According to the cellular, humoral, biochemical, and clinical manifestations of EAMG, the I-A mutation converted an EAMG susceptible strain (B6/Kh) into a relatively resistant strain (bm12). The relative resistance to EAMG induction in bm12 may be due to the lack of Ia.8 and/or Ia.39 determinants and/or quantitative expression of Ia antigens.

Effect ofSchizandra chinensis lignans on cell division in the corneal epithelium and tongue of albino rats exposed to chronic cold stress

The authors study the possibility of correcting cellular manifestations of disadaptation following chronic exposure to cold stress by means of preparations of Sch. chinensis. The model of chronic stress was cooling male albino rats daily for 1.5 h to a temperature of 28-30 C for 28 days. Since differences between levels of proliferation in intact animals and in the rats receiving 1.9% ethanol solution were absent, values obtained in the group of intact animals are presented in a table as the control. The animals underwent euthanasia 48 hours after the final exposure to the cold. The rats received an injection of tritium-thymidine one hour before sacrifice. It is shown that the results confirm those in previous studies of stimulation of DNA synthesis and mitotic activity in the corneal and lingual epithelium of albino rats during chronic exposure to stress.

1 - Contributions of Immunocytochemistry to Gynaecological Pathology

The immunoperoxidase technique is relatively simple and inexpensive, and once established it can be easily adapted to any number of antigens. The method has already been employed to localize a wide variety of enzymes, proteins, polypeptide hormones, steroid hormones, immunoglobulins, and viral and protozoal antigens. The only limitations of the immunoperoxidase technique are the availability of specific antisera and the ability of the cellular product being tested to retain its antigenicity through the process of fixation, dehydration and embedding. It is now apparent that, with the exception of a few labile antigens, most cellular products survive routine fixation to the extent that sufficient antigenic determinants remain to permit their recognition. Meaningful interpretation of the results, however, depends on thoughtful evaluation of the methodology. This requires careful immunological and tissue controls. Standardization of antibodies used as reagents, particularly in the rapidly burgeoning field of monoclonal antibodies, is essential in order that studies performed by different laboratories can be compared. The application of immunocytochemistry to the study of gynaecological disease has been relatively recent, but it is apparent that this technique is a powerful tool with which to confirm and extend the morphological observations made over the last century. By taking advantage of the high degree of specificity of antibodies, immunocytochemistry has assumed a prominent role as a highly specific 'special stain'. Of perhaps even greater significance is the use of this technique to explore and characterize the biochemical features of cells within the framework of conventional morphology. Thus, gynaecological pathology is on the threshold of a new era in which the pathologist can now study the cellular manifestations of disease on both a functional and a morphological basis.

Formation of gamma-glutamyl-epsilon-lysine bridges between membrane proteins by a Ca2+-regulated enzyme in intact erythrocytes.

A rise in the intracellular concentration of Ca2+-ions in human erythrocytes causes the formation of high-molecular-weight membrane protein polymers, cross-linked by gamma-glutamyl-epsilon-lysine side chain bridges. Cross-linking involves proteins at the cytoplasmic side of the membrane (band 4.1, spectrin, and band 3 materials) and the reaction is catalyzed by the intrinsic transglutaminase. This enzyme is regulated by Ca2+-ions and it exits in a latent form in normal cells. The protein polymer, isolated from the membranes of Ca2+-loaded intact human red cells, is heterogeneous in size and may contain as many as 6 moles of gamma-glutamyl-epsilon-lysine cross-links per 100,000 gm of protein. Synthetic compounds, which either compete against the epsilon-lysine cross-linking functionalities of the protein substrates (eg, histamine, aminoacetonitrile, cystamine) or directly inactivate the transamidase (eg, cystamine), inhibit the membrane polymerization reaction in intact human erythrocytes. They also interfere with the Ca2+-induced irreversible shape change from discocyte to echinocyte and inhibit the irreversible loss of membrane deformability. Thus, the transamidase-catalyzed production of gamma-glutamyl-epsilon-lysine cross-links in the membrane may be a common denominator in these cellular manifestations.

Cyclic AMP, the microtubule-microfilament system, and cancer.

Additional evidence is presented for the previously proposed existence in normal fibroblasts of a cyclic AMP-dependent network of microtubules and microfilaments, which is connected with cell membrane elements on one end and with nuclear structures on the other and whose disorganization leads to malignant transformation. In the presence of cyclic AMP derivatives sufficient to promote integrity of this network, cell growth limitation in suspension, increased transport of alpha-[14C]aminobutyrate, and the relatively tranquilized membrane of the normal fibroblast are also achieved. A pattern of distribution of actin and tubulin has been demonstrated showing aggregated actin deposits which are presumably responsible for the oscillatory knob activity of cells with the transformed habitus. Specific orientations of microtubular and filamentous elements with respect to the nucleus can be demonstrated. The hypothesis that the microtubular-microfilamentous structure conveys growth-regulatory information from the cell membrane to the nucleus and that its disorganization can lead to malignancy has been extended to explain various cellular manifestations.

Cellular mechanisms involved in cyclic stroma renewal of the uterus. III. Cells of the immune response.

The principal cell types associated with the humoral immune response (monocyte-macrophages, lymphocytes, and plasma cells) are numerous in the endometrial stroma of the uterus during the first four postpartum days in two types of mammals, the marsupial North America opossum and the eutherian albino rat. This transietn cellular differentiation coincides with the physiologic period of rapid uterine regression which includes massive reduction in the amount of extracellular stromal material. In addition, heterophils and eosinophils, cell types also known to be associated with phagocytic and immunologic activity, appear in the stroma during the first two postpartum days; their presence may, however, be associated more directly with the postpartum estrus that occurs on day 1 postpartum than with endometrial regression. Thus, the five cell types, which are known in pathologic conditions to be components present in the inflammatory response to a foreign antigen, are conspicuously present in the normal regressing endometrium. Furthermore, there is ample ultrastructural evidence of frequent macrophagic-lymphocytic interaction, transformation of lymphocytes, and active secretion by plasma cells during this early postpartum period. An hypothesis has been derived by uniting this new description of endometrial stromal cell differentiation with the existing literature on uterine collagenase activity, an important feature of postpartum regression (reviews of Gross, '74; Harris and Krane, '74). It is based on the assumption that during regression the extracellular action of neutral collagenase (and possibly other extracellular proteases) release new antigenic sites in proteins located in the ground substance. In the case of collagenase, these transient antigenic sites would arise at the locus of enzymic cleavage as well as from the subsequent denaturation of the fragments of the collagen molecule. This endogenous antigenic stimulus would be strong and temporary, and would lead to the cellular manifestations of the transient humoral immunologic response which are evident in the regressing stroma of these two mammals. This humoral immune reaction may be one of the regulatory mechanisms involved in the cyclic renewal of the extracellular compartment of the uterine stroma.