Melatonin treatment for prevention of oxidative stress: involving histopathological changes

This study was undertaken to test the effect of irradiation on the histopathology of the hypothalamus and cerebral cortex. In addition, the probable effects of radiotherapy on the activities of antioxidant enzymes and levels of nitric oxide (NO) in the plasma were investigated as well. The effects of melatonin treatment on radiotherapy-based central nervous system (CNS) damage were also studied. For this purpose, the rats were randomized into four groups. The first group was the control group (sham-exposed group), the second group received only melatonin, the third group was irradiated and the fourth group received both melatonin and irradiation. Plasma samples of rats were collected for measuring the activities of superoxide dismutase (SOD), catalase (CAT) and the levels of NO. 24 h after the interventions, tissue samples were obtained from the hypothalamus and the cerebral cortex for the light microscopic investigations. These tissues were mostly affected by radiation. The results indicated that the application of radiation significantly enhanced the levels of plasma SOD and NO. On the other hand, melatonin pretreatment prevented the decrease in plasma CAT activity induced by irradiation. It was found that the application of melatonin could significantly prevent the irradiation-induced damages. Light microscopic results revealed that the damage of the CNS by radiation was prevented by the application of melatonin.     

Comparative morphometric analysis of intraepidermal and dermal lymphocytes in early mycosis fungoides and some inflammatory dermatoses

OBJECTIVE: Early stage mycosis fungoides (MF) may be indistinguishable from some inflammatory dermatoses (IDs) histopathologically. Various morphologic features of lymphocytes in epidermis and dermis may help to differentiate early-stage MF from other IDs. STUDY DESIGN: We studied 25 cases of early-stage MF and 30 cases of various IDs with prominent exocytosis. The following nuclear variables were measured on dermal and epidermal lymphocytes in MF and IDs (control) groups: nuclear area and perimeter, area convex hull, perimeter convex hull, diameter equivalent circle, minimum feret, maximum feret and form factor. All measurements were done using routinely prepared and hematoxylin-eosin-stained slides. RESULTS: There were statistically significant differences (p < 0.01) for all of the morphometric variables between early-stage MF and IDs. CONCLUSION: Our results revealed that the nuclear contour irregularities of intraepidermal lymphocytes are higher than those of dermal lymphocytes in MF. Their nuclear geometry is also different. Comparison of the nuclear features of intraepidermal with dermal lymphocytes may provide additional support in the diagnosis of early-stage MF.     

Improvement and impairment of visually guided behavior through LTP- and LTD-like exposure-based visual learning

Cellular studies have focused on long-term potentiation (LTP) and long-term depression (LTD) to understand requirements for persistent changes in synaptic connections. Whereas LTP is induced through high-frequency intermittent stimulation, low-frequency stimulation evokes LTD. Because of the ubiquitous efficacy of these protocols, they are considered fundamental mechanisms underlying learning. Here we adapted LTP/LTD-like protocols to visual stimulation to alter human visually guided behavior. In a change-detection task, participants reported luminance changes against distracting orientation changes. Subsequently, they were exposed to passive visual high- or low-frequency stimulation of either the relevant luminance or irrelevant orientation feature. LTP-like high-frequency protocols using luminance improved ability to detect luminance changes, whereas low-frequency LTD-like stimulation impaired performance. In contrast, LTP-like exposure of the irrelevant orientation feature impaired performance, whereas LTD-like orientation stimulation improved it. LTP-like effects were present for 10 days, whereas LTD-like effects lasted for a shorter period of time. Our data demonstrate that instead of electrically stimulating synapses, selective behavioral changes are evoked in humans by using equivalently timed visual stimulation, suggesting that both LTD- and LTP-like protocols control human behavior but that the direction of changes is determined by the feature incorporated into the stimulation protocol.     

Temozolomide-related infections: review of the literature

Temozolomide (TMZ) is an alkylating, antineoplastic agent which is being used to treat cases of refractory anaplastic astrocytoma, newly-diagnosed glioblastoma multiforme and metastatic melanoma. TMZ causes lymphopenia and T-cell dysfunction in most of the patients. Related to this toxicity several opportunistic infections have been reported in the literature, but were not well characterized. To further investigate this topic, relevant English language studies were identified through Medline. There were 36 previously reported cases of infection related to TMZ. The median age of the cases was 55 years (range 33-73). The most frequently experienced infections were mucocutaneous candidiasis (n=11; 28.2%), herpes zoster (n=5; 12.8%), herpes simplex virus (n=4; 10.2%), cytomegalovirus (CMV) (n=5; 12.8%), pneumocystis carinii pneumonia (PCP) (n=3; 7.6%), hepatitis B virus (HBV) (n=2; 5.1%) and others (n=9; 23%). Mortality rates were 28.5% (n=4/14) in patients with reported outcome. In this survey, about one third of the TMZ-related severe infections resulted in death. Patients treated with TMZ are at increased risk for opportunistic viral and bacterial infection. Therefore, close monitoring of patients receiving TMZ for opportunistic infections should be carried out.     

Alien marine fishes deplete algal biomass in the Eastern Mediterranean

One of the most degraded states of the Mediterranean rocky infralittoral ecosystem is a barren composed solely of bare rock and patches of crustose coralline algae. Barrens are typically created by the grazing action of large sea urchin populations. In 2008 we observed extensive areas almost devoid of erect algae, where sea urchins were rare, on the Mediterranean coast of Turkey. To determine the origin of those urchin-less 'barrens', we conducted a fish exclusion experiment. We found that, in the absence of fish grazing, a well-developed algal assemblage grew within three months. Underwater fish censuses and observations suggest that two alien herbivorous fish from the Red Sea (Siganus luridus and S. rivulatus) are responsible for the creation and maintenance of these benthic communities with extremely low biomass. The shift from well-developed native algal assemblages to 'barrens' implies a dramatic decline in biogenic habitat complexity, biodiversity and biomass. A targeted Siganus fishery could help restore the macroalgal beds of the rocky infralittoral on the Turkish coast.     

Human Cdc14B promotes progression through mitosis by dephosphorylating Cdc25 and regulating Cdk1/cyclin B activity

Entry into and progression through mitosis depends on phosphorylation and dephosphorylation of key substrates. In yeast, the nucleolar phosphatase Cdc14 is pivotal for exit from mitosis counteracting Cdk1-dependent phosphorylations. Whether hCdc14B, the human homolog of yeast Cdc14, plays a similar function in mitosis is not yet known. Here we show that hCdc14B serves a critical role in regulating progression through mitosis, which is distinct from hCdc14A. Unscheduled overexpression of hCdc14B delays activation of two master regulators of mitosis, Cdc25 and Cdk1, and slows down entry into mitosis. Depletion of hCdc14B by RNAi prevents timely inactivation of Cdk1/cyclin B and dephosphorylation of Cdc25, leading to severe mitotic defects, such as delay of metaphase/anaphase transition, lagging chromosomes, multipolar spindles and binucleation. The results demonstrate that hCdc14B-dependent modulation of Cdc25 phosphatase and Cdk1/cyclin B activity is tightly linked to correct chromosome segregation and bipolar spindle formation, processes that are required for proper progression through mitosis and maintenance of genomic stability.