Ultrastructural investigation of acidocalcisomes and ATPase activity in yeast Candida guilliermondii NP-4 as 'complementary' stress-targets.

As a result of electron microscopic studies of morphogenesis in yeast Candida guilliermondii NP-4, the formation of new structures of volutin acidocalcisomes has been established within the cell cytoplasm. Under influence of X-irradiation, the changes in morphometric and electron-dense properties of yeast cells were identified: in yeast cytoplasm, the electron-dense volutin granules were increased up to 400 nm in size. After 24-h post-irradiation incubation of yeasts, the large volutin pellets are fragmented into smaller number particles in size up to 25-150 nm. The ATPase activity in yeast mitochondria was changed under X-irradiation. In latent phase of growth, ATPase activity was decreased 1·35-fold in comparison with non-irradiated yeasts. In logarithmic phase of growth, ATPase activity was three times higher than in latent phase, and in stationary phase of growth it has a value similar to the latent phase. Probably, the cells receive the necessary energy from alternative energy sources, such as volutin. Electron microscopy of volutin granule changes might serve as convenient method for evaluation of damages and repair processes in cells under influence of different environmental stress-factors.

Dual-Targeted Phototherapeutic Agents as Magic Bullets for Cancer.

Imagine the ideal cancer drug that only kills cancer cells and does not affect nearby noncancerous cells. In the words of Paul Ehrlich, the drug acts like a magic bullet. This Topical Review summarizes an emerging new strategy to achieve this audacious goal. The central concept is a dual-targeted phototherapeutic agent for photodynamic or photothermal therapy. The dual-targeted phototherapeutic agent promotes cancer cell specificity by leveraging three levels of selectivity. Cell death will only occur in the anatomical location that is illuminated with light (Selectivity Level 1) and in cancer cells within the illumination area that have selectively accumulated the agent (Selectivity Level 2). The cancer cell killing effect is highly localized if the agent accumulates in hypersensitive intracellular organelles (Selectivity Level 3). The common targeting units for cancer cells and organelles are described, along with recent examples of dual-targeted phototherapeutic agents that incorporate these two classes of targeting units.

Tea polyphenols protect against irradiation-induced injury in submandibular glands' cells: a preliminary study.

AIM: To study the protective effect of tea polyphenols (TPs) on submandibular glands affected by radiation injury. METHODS: Sixty rats were randomly divided into radiation group (R-group, N = 30) and TP-pre-treated-radiation group (TPR-group, N = 30). The rats were intragastrically administered with TP or normal sodium from 14 days before radiation, continuously daily, until the experiment. All the rats in both groups were irradiated with a single exposure dose of 15 Gy gamma rays that were delivered to the head and neck areas. Ten rats of each group were anatomised on the 3rd, 6th and 30th day after irradiation, respectively. The submandibular glands of the rats were removed for the study. The morphologic changes of the submandibular glands were observed by transmission electron microscopy (TEM). The terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP)-biotin nick-end labelling (TUNEL) method was used to detect apoptosis of the submandibular glands' cells. RESULTS: Electron microscope observation of the submandibular glands showed that the lesions of the TPR-group were mild. Change in apoptosis of the cells was not obvious compared with the R-group. The cell apotosis was typical after irradiation in the R-group. Apoptosis index that was detected in the cells of submandibular glands of the TPR-group was statistically significantly decreased compared with the R-group (P < 0.01) on the 3rd, 6th and 30th day after irradiation. CONCLUSION: TP could protect submandibular glands from radiation injuries, and the protection mechanism may be realised by anti-apoptosis.

[Effect of external ionizing radiation on morphofunctional indices of the hypothalamus, hypophysis and adrenal glands]. / Vplyv zovnishn'oho oprominennia na morfofunktsional'ni pokaznyky hipotalamusa, hipofiza i nadnyrkovykh zaloz.

The laboratory rats exposed to one-time external ionizing radiation have been found to have phase changes of morphofunctional and secretory cells activity of hypothalamus, hypophysis, cortex and medullary of adrenal glands. The first phase called reactive (3-7 days) is characterized by enhancing energy-producing, protein-synthesizing and secretory functions of secretory sells of hypothalamus supraoptic nucleus, corticotrophic cells of adenohypophysis, adrenocorticytes of cortex and adrenocytes of medullary of adrenal glands. The second phase of dystrophic changes (7-14) is characterized by different degree of distrophic-destructive changes. The third phase (14-1 month) is characterized by compensatory adaptative and recovery processes during which we can see on the background of dystrophic changes the processes of intracellular reparative regeneration. The fourth phase (1-3 months) is characterized by virtually complete recovery of morphofunctional and secretory activity of most cells of hypothalamus, hypophysis and adrenal glands.

Molecular response of human glioblastoma multiforme cells to ionizing radiation: cell cycle arrest, modulation of the expression of cyclin-dependent kinase inhibitors, and autophagy.

OBJECT: Ionizing radiation is the gold-standard adjuvant treatment for glioblastoma multiforme (GBM), the most aggressive primary brain tumor. The mechanisms underlying neoplastic glial cell growth inhibition after administration of ionizing radiation, however, remain largely unknown. In this report, the authors characterize the response of GBM cells to ionizing radiation and elucidate factors that correlate with the radiosensitivity of these tumors. METHODS: Six human GBM cell lines were subjected to increasing doses of radiation. Each demonstrated a dose-dependent suppression of cell proliferation. In the most radiosensitive cell line, the authors demonstrated a transient increase in the expression of the cyclin-dependent kinase inhibitors (CDKIs) p21 and p27, which corresponded with a G1 cell-cycle arrest. In contrast, the most radioresistant cell line demonstrated a decrease in p21 and p27 expression levels, which correlated with a failure to arrest. Apoptosis did not occur in any cell line following irradiation. Instead, autophagic cell changes were observed following administration of radiation, regardless of the relative radiosensitivity of the cell line. CONCLUSIONS: These findings elucidate some of the molecular responses of GBMs to irradiation and suggest novel targets for future therapy.

Ultrastructural apoptotic lesions induced in bone marrow after neptunium-237 contamination.

This study describes the ultrastructure of lesions induced by neptunium-237 (237Np), a by-product of uranium in nuclear reactors, in the bone marrow. A group of rats were given a single injection of 237Np-nitrate solution in order to observe the acute toxicity effects of this actinide. Electron microscopy was used to describe the different lesions. Observations included the swelling of the cell membrane, nuclear membrane lyses, abnormal chromatin condensation or nucleus convolution. These ultrastructural alterations of the nucleus and the cellular membrane appeared shortly after treatment. This study demonstrates the toxic effects of neptunium and its implication in the induction of apoptosis in bone marrow.

Role of lycopene in recovery of radiation induced injury to mammalian cellular organelles.

Whole body exposure of male rats to 7 Gy gamma irradiation increased lipid peroxidation in the liver resulting in biomembrane damage of subcellular structures and release of their enzymes. This is evidenced by increase of thiobarbituric acid-reactive substances (TBARS) in mitochondria, lysosomes and microsomes. This was associated with a decrease in activity of the enzymes specific for each subcellular fraction; namely, mitochondrial glutamate dehydrogenase (GDH), lysosomal beta-glucuronidase and microsomal glucose 6-phosphatase. This was paralleled by an increased activity of these enzymes in the cytosol. Rats were supplemented with lycopene, a carotenoid present in tomatoes (5 mg/kg weight/day), by gavage, for 7 days before exposure to 7 Gy gamma irradiation. This resulted in diminishing amount of TBARS recorded for each subcellular structure in the liver of irradiated animals. Significant amelioration in the decrease recorded for the activity of mitochondrial glutamate dehydrogenase, lysosomal beta-glucuronidase and microsomal glucose 6-phosphatase was observed. This was associated with significant amelioration in the increase recorded for the activity of these enzymes in the cytosol. It is postulated that lycopene could play an important role in the recovery of the integrity of biological membranes of the liver after radiation injury.

Structural and biochemical basis for the UVB-induced alterations in epidermal barrier function.

Ultraviolet light (UVR) induces a myriad of cutaneous changes, including delayed disruption of the permeability barrier with higher doses. To investigate the basis for the UVB-induced barrier alteration, we assessed the epidermal lamellar body secretory system at various time points before and after barrier disruption with a single high dose of UVB (7.5 MED) to murine epidermis. Morphological data were correlated with changes in epidermal proliferation and lipid synthesis, indicative of lamellar body generation. Twenty-four hours following UVB, the stratum corneum (SC) is normal, but a layer of abnormal, vacuolated, and lamellar body (LB)-deficient cells is present, immediately beneath the stratum granulosum (SG)/SC interface. Immediately subjacent to this band of damaged cells, normal keratinocytes that contain intact LBs are present. By 72 h, concomitant with the appearance of a barrier abnormality, extensively damaged cells persist at the SC/SG interface, and abnormal lamellar membrane structures appear in the lower SC. Upper stratum spinosum (SS) and lower SG cells appear normal, with increased numbers of LBs. A barrier abnormality is still present at 96 h, in association with membrane abnormalities in the lower SC interstices, but up to four normal appearing, subjacent SG cell layers are present. By 120 h, accelerated LB formation and precocious LB extrusion occur throughout the thickened SG; normal lamellar membranes are present in the lower SC; and barrier recovery is almost complete. Whereas, epidermal synthesis of the major barrier lipid species (i.e., cholesterol, fatty acids, and ceramides, including acylceramides) is reduced or unchanged at 24 and 48 h, it increases significantly 72 h after exposure to UVB. Therefore, the delayed disruption of the permeability barrier following acute UVB exposure results from the arrival of a band of lamellar body-incompetent (i.e., damaged) cells at the SG/SC interface. The subsequent, rapid recovery of the barrier, in turn, results from compensatory hyperplasia of subjacent, undamaged SS/SG cells, generating increased numbers and contents of LB. These results underscore the critical role of the stratum compactum in mediating barrier function, and suggest that beneficial therapeutic effects of UV exposure may be due to enhanced lipid production and barrier regeneration.

Why does the light-gradient photovoltage from photosynthetic organelles show a wavelength-dependent polarity?

The light-gradient photovoltage from photosynthetic organisms and organelles is thought to arise from the primary charge separation in the reaction centers. The current explanation of the effect is the stronger excitation of the membrane side of a vesicle facing the light source than the one on the opposite side. Together with the known orientation of reaction centers, this explanation predicts unequivocally the polarity of the photovoltage. However, a polarity opposite to the one expected has often been reported. A dependence of the polarity on the wavelength has been published but no explanation was given (Gräber, P., and H.-W. Trissl. 1981. FEBS Lett. 123:95-99). Here we report on a theoretical treatment of light propagation and interference in pigmented and nonpigmented multilayers. A model calculation is carried out for a pair of membranes, demonstrating the wavelength-dependent light distribution as well as the relative photovoltage and its polarity. When the membranes contain no chromophores or when the absorption coefficient is low, the predicted polarity to that expected from a simple macroscopic absorption behavior. The model is tested by comparing new photovoltage data obtained at 532 nm as well as in the blue and red absorption bands of chlorophyll in chloroplasts. It is concluded that outside the main absorption bands the amplitude and polarity of the photovoltage is determined by the ratio of the refractive indices of the membrane and the medium.