Is pneumatosis cystoides intestinalis gas-distended and ruptured lymphatics? Reappraisal by immunohistochemistry.

Context: Pneumatosis cystoides intestinalis (PCI) is a condition with multiple gas-filled cysts within the bowel wall, associated with diverse background diseases. Its pathogenesis is still a mystery. Some previous observations scattered in the literature have suggested an association of the cystic spaces in PCI with the lymphatics.

[Multidrug resistance increase of tumor cells at the effect of radiation and phorbol ether depends on protein kinase C and reactive oxygen species].

The effects of phorbol ether (PMA) and ionizing radiation on multidrug resistance (MDR) of human larynx cancer cells HEp-2 and the dependences of these effects on protein kinase C (PKC) activity and reactive oxygen species (ROS) production were studied. MDR was determined by transport rate of rhodamine 123 off cells and production of ROS in cells was measured by means of 2'7'-dichlorodigidrofuorescein oxidation to fluorescent 2',7'-dichlorofluorescein. ROS production was increased in cells at PMA treatment.

[On the biophysical mechanism of the circum-hour cell rhythm and its role in metabolism].

The universal biophysical mechanism of "circum-hour" oscillations of parameters and properties of various cells and their organelles was considered. The mechanism is the result of nonspecific responses of cells to any damaging agents. At the basis of the "circum-hour" mechanism is the earlier reported inverse dependence of the activity of enzymes on the concentration of low-molecular weight organic substances in medium.

[On the mechanism of the nonspecific cell response to the action of damaging agents and the nature of hormesis].

A conception of the molecular mechanism of the universal nonspecific cell response (NCR) to the action of all damaging factors of physical and chemical nature is described. The mechanism is shown to be closely related to the general principles of the structural-functional organization of cells and to the properties of biological macromolecules. Among them are the phenomenon of nonspecific regulation of the enzyme activity by low-molecular substances and the compartmentation of the latter within the cell, which is provided by the system of intracellular membranes.

[Interphase death of irradiated thymocytes--result of the "bystander effect"].

It was shown that interphase death of thymocytes, which mechanism was established by author's laboratory already over 10 years ago belongs to phenomena which recently was named as caused by "bystander effect".

Thymidylate synthase expression in stage II and III colon cancer: a retrospective review.

This study is a retrospective analysis of thymidylate synthase (TS) levels in patients with stage II (T3 or T4) and III colon cancer. Two groups of patients were identified: one undergoing surgery alone (98 patients) and the second receiving adjuvant 5-fluorouracil chemotherapy (112 patients). TS analyses were carried out using the 106 monoclonal antibody and a published grading system dividing staining into high and low intensity.

[Problems of the mechanism of radiation and chemical hormesis].

Based on the "membrane" mechanism of biological action of low radiation doses, described earlier, a possible common explanation of radiation and chemical hormesis initiation is proposed.

[Mechanism of DNA repair induction by action of ionizing radiation on cells].

A mechanism is presumed regarding the induction of DNA damage repair at crossing from low to high ionisation doses. Radiation even in low doses disturbs the permeability of membranes and increases the intracellular pH. Alkalation of cells induces changes in chromatin conformation and DNA packing in them.

Hypothesis regarding a membrane-associated mechanism of biological action due to low-dose ionizing radiation.

A novel theory is proposed regarding the action of ionizing radiation in the range of very low doses. The basic premise of the theory presented is that the low-dose effect cannot be explained by direct damage to the DNA (as has generally been assumed) and that effects on cellular membranes should be considered instead. Low-dose radiation damaging the plasma membrane decreases the concentration of low-molecular weight compounds (LMWC) inside the cell, which through an unspecific mechanism induces an activation of all enzymes.

Ovarian histoplasmosis in systemic lupus erythematosus.

Histoplasma capsulatum is a pathogenic fungus endemic to North, Central, and South America. Histoplasmosis is primarily acquired by inhalation and in immunocompetent hosts infection is generally limited to the lungs. Histoplasmosis may disseminate systemically in hosts with defective cell-mediated immunity or massive inoculation.

[Extrapolation of dose-effect relationships for cytogenetic aberrations from high to low doses].

It is known, that extrapolation of dose response curve for cytogenic lesions, based on the linear non-threshold concept is not correct due to anomalies in the low dose region, among them the dose intervals of the so-called "low dose effects" (LDE) and "plato"-effect. As a rule they are attributed to assumed heterogeneity of cell populations or to existence of several repair systems. Analysing the data on modification the cytogenetic lesions we concluded, that in the whole low-dose range functions one on the same repair system, but it "switches on" only at sufficient reorganization of chromatin (accompanied by expression of before "silent" genes), caused by radiation-induced increase of the membranes permeability.

[The role of cell interaction in initiation of radiation-induced death of thymocytes and apoptosis].

The experimental evidence of crucial importance of cell interactions for initiation of radiation-induced thymocyte death was obtained. It has been proposed that ionizing radiation, in contrast to many other cytotoxic agents, initiates thymocyte death simultaneously by different independent pathways, affecting all cellular components. The concept of apoptosis as "programmed cell death" has been critically discussed.

Soft tissue Rosai Dorfman disease mimicking inflammatory pseudotumor: a diagnostic pitfall.

Rosai Dorfman disease, or sinus histiocytosis with massive lymphadenopathy (SHML), may be a difficult diagnosis to make, especially in extranodal sites. With soft tissue involvement the characteristic diagnostic features of large histiocytic cells with emperipolesis may be overshadowed by a fibroinflammatory component. In these cases it is easy to confuse this lesion with reactive nodules and benign and malignant neoplasms.

[Is apoptosis a "programmed cell death"?].

Many authors consider apoptosis as a programmed cell death (PCD). Their opinion is based usually on the dependence of cell death on the protein-opinion and RNA synthesis, on the intranucleosomal fragmentation of DNA and on the expression of genes, which can induce apoptosis. However our analysis of numerous literature data on the apoptotic death (judging by their morphological criteria) of different cell kinds induced by various agents shows: internucleosomal fragmentation of DNA is neither a trigger, nor a reliable proof for apoptotic death; protein- and RNA synthesis, as well as expression of P53 genes is also not a necessary condition for that and is important only in some combinations of the cell type and state and the nature of the damaging agent.

[A single mechanism for the initiation of different effects of low doses of ionizing radiation].

Main regularities of different endpoints of low dose effects (adaptive response, stimulation of proliferation, special radiosensitivity of lymphoid cells, and others) have been examined. It has been shown that these endpoints have a commonness for the dose interval, the shape of the dose-effect curve, the reverse effect of dose rate, non-specificity toward initiating agents, and others. An explanation is suggested for the common mechanism of the initiation of all the studied low dose effects, basing on the theory of the non-specific reaction of cell to external influences.

Role of arachidonic acid metabolism in thymocyte apoptosis after irradiation.

The present study demonstrates that DNA fragmentation, nuclear pycnosis and trypan blue staining of irradiated thymocytes is prevented by inhibition of the lipoxygenase pathway of arachidonic acid metabolism and is not affected by cyclooxygenase inhibition. Exposed to irradiation [3H]arachidonic acid-labeled thymocytes release radioactive products to the external medium. The process is blocked by the lipoxygenase inhibitor, nordihydroguaiaretic acid.

[The mechanism of the initiation of low-dose effects].

A mechanism for initiation effects is proposed. This is based on the theory of non-specific response of cells to damaging influences, which has been developed by the author previously. The effects (adaptive response, stimulation of proliferation, etc.

Dependence of thymocyte apoptosis on protein kinase C and phospholipase A2.

The effect of inhibitors and activators of protein kinase C and phospholipase A2 on radiation-induced apoptosis of rat and mouse thymocytes has been studied. It is shown that the apoptosis is prevented by the protein kinase C inhibitor 1-(5-isoquinolinylsulfonyl)-2-methylpiperasine dihydrochloride and is potentiated by protein kinase C activator phorbol 12-myristate 13-acetate, calcium ionophore A23187 and concanavalin A. The protein kinase C activators initiate apoptosis in mouse but not in rat thymocytes.

Invasive Clostridium septicum infection in association with colorectal carcinoma.

The association between invasive Clostridium septicum infection and colorectal carcinoma is examined by the presentation of three cases and a review of the literature. In the first two cases the patients presented with nontraumatic metastatic clostridial gas gangrene. In the third case a patient with chemotherapy-induced myelosuppression from concomitant multiple myeloma had a necrotizing transmural infection of the right colon.

[The cause-effect relationships between different indices of radiation lesions of the thymocytes].

The dependence of the kinetics of different thymocyte injuries of the experimental conditions was investigated. It was shown that the rate of cell death detecting by cell staining decreases with the increase of the dye molecular size. Different organic substances decrease the staining rate of the dead cells with trypan blue but increase the rate of DNA fragmentation.

Intercellular interactions in the interphase death of irradiated thymocytes.

The effect of the interaction of different types of cells on the interphase death and pycnosis of thymocytes irradiated in vitro was studied. When removed from the thymus suspension of cells with natural killer activity, medullary thymocytes and macrophages did not change the radiation-induced death of cortical thymocytes. On the other hand, postirradiation incubation of cortical thymocytes together with unirradiated thymocytes or with cells of certain other cell lines diminished thymocyte death.

[Toxic effects of heavy metal salts on intact and irradiated cultured mammalian cells].

The toxicity of solutions of K2Cr2O7 and NiSO4.8H2O for cultivated Chinese hamster fibroblasts and murine lymphoma Sp-2 cells was determined using three criteria of damage: cell death (dyeing with trypan blue), inhibition of cell proliferation and their colony-forming activity. It was shown that both salts have equal toxicity in (10(-3)-10(-2)) M interval for both culture investigated relative to inhibition of cell proliferation.

[The intercellular interactions in the interphase death of irradiated thymocytes. A study of the nature of the mediator of the interaction of irradiated thymocytes].

A study was made of the influence of cytosol and conditioned medium, obtained at different times of incubation of irradiated thymocytes, on native thymocytes, as well as of the influence of mixing the suspension and changing the medium and the enzyme inhibitors, involved in metabolism of arachidonic acid, on the radiation injury to thymocytes. Cytosol of thymocytes, incubated for 60 min after irradiation, was shown to exert an insignificant toxic effect on native thymocytes. The conditioned medium of irradiated thymocytes is virtually ineffective.

[The intercellular interactions in the interphase death of irradiated thymocytes. A study of the influence of different cells on thymocyte interphase death].

The influence of different cells on death and pycnosis of thymocyte nuclei after in vitro irradiation has been investigated. It has been shown that the removal from the thymocyte suspension of cells, having the activity of natural killers, medullar thymocytes, and macrophages, does not influence the radiation-induced damage to cortical thymocytes. The injury of exposed thymocytes decreases, however, after incubation them with nonirradiated thymocytes or cultured cells, the efficiency of the latter being dependent on the type of cells.