Formation and function of accessory nuclei in the oocytes of the bird louse,Eomenacanthus stramineus (Insecta,Mallophaga)

In the oocytes of Eomenacanthus stramineus accessory nuclei arise by budding from the nuclear envelope. It is suggested that microtubules and the thick layer of the nuclear lamina are involved in this process. Newly formed accessory nuclei contain aggregations of fibrillogranular material. These aggregations are slightly Feulgen positive, RNA negative and stain positively with the AgNOR method. During later developmental stages one dense, RNA-positive inclusion appears in each accessory nucleus. These inclusions consist of on Ag-NOR-positive cortical layer and an Ag-NOR-negative core. The function of accessory nuclei in the species investigated is discussed in the light of these results.     

Formation of an egg envelope in the pycnogonid, Propallene longiceps (Pycnogonida, Callipallenidae)

Vitellogenic oocytes of all pycnogonids studied so far contain dilated elements of the endoplasmic reticulum, filled with characteristic electron-dense bodies. During vitellogenesis these bodies fuse and form larger, almost spherical granules that were traditionally interpreted as nascent yolk granules. Here, we present the results of ultrastructural investigations of previtellogenic and early vitellogenic oocytes of Propallene longiceps (Pycnogonida, Callipallenidae). We show that the intra-cisternal bodies/granules of pycnogonids are not involved in vitellogenesis but contain macromolecules that are released from the oocyte and contribute to the formation of an egg envelope. The obtained results are discussed in a phylogenetic context. We suggest that the presence of the intra-cisternal electron-dense bodies in the oocyte cytoplasm represents a plesiomorphic character of arthropods inherited from the arthropod ancestor.     

The ovaries of Mecoptera: basic similarities and one exception to the rule

Two entirely different types of ovaries (ovarioles) have been described in mecopterans. In the representatives of Meropeidae, Bittacidae, Panorpodidae and Panorpidae the ovarioles are of the polytrophic-meroistic type. Four regions: a terminal filament, germarium, vitellarium and ovariole stalk can be distinguished in the ovarioles. The germaria house numerous germ cell clusters. Each cluster arises as a result of 2 consecutive mitoses of a cystoblast and consists of 4 sibling cells. The oocyte always differentiates from one of the central cells of the cluster, whereas the remaining 3 cells develop into large, polyploid nurse cells. The vitellaria contain 7-12 growing egg chambers (= oocyte-nurse cell complexes). In contrast, the ovaries of the snow flea, Boreus hyemalis, are devoid of nurse cells and therefore panoistic (secondary panoistic). The ovarioles are composed of terminal filaments, vitellaria and ovariole stalks only; in adult females functional germaria are absent. Histochemical tests suggest that amplification of rDNA takes place in the oocyte nuclei. Resulting dense nucleolar masses undergo fragmentation into multiple polymorphic nucleoli. The classification of extant mecopterans as well as the phylogenetic relationships between Mecoptera and Siphonaptera are discussed in the context of presented data.     

Correlation between NADPH-diaphorase and iNOS in bank vole Leydig cells in vitro and in testicular sections with the use of histochemistry and immunocytochemistry

Histochemistry for NADPH-diaphorase detects an enzymatic activity associated with nitric oxide synthase while immunohistochemistry detects the nitric oxide synthase molecule. NADPH-diaphorase and inducible isoform of nitric oxide synthase in Leydig cells in vitro and in testis sections of the bank vole were demonstrated histochemically and immunocytochemically. Histochemical studies revealed localization of NADPH-diaphorase reaction product in the cytoplasm of cultured Leydig cells as well as in the interstitial area, mainly in Leydig cells and in vascular endothelium. Distribution pattern of NADPH-diaphorase was different in Leydig cell cytoplasm of individual cells. Using immunocytochemistry, the immunoreactivity for nitric oxide synthase was observed both in cultured Leydig cells and testis sections. Moreover, a co-localization of positively immunostained cells with those histochemically detected was noticed. Addition of hCG to the cultured medium or injections in vivo resulted in a small decrease in reaction intensity in Leydig cells. Treatment with N omega-nitro-L-arginine methyl ester resulted in distinctly weaker reactivity of the enzymes studied which was correlated with a higher testosterone and estradiol levels in Leydig cells measured radioimmunologically. The results have indicated that nitric oxide synthase is able to act directly within the male gonad regulating androgen secretion by Leydig cells.     

Smokers with CT Detected Emphysema and No Airway Obstruction Have Decreased Plasma Levels of EGF,IL-15, IL-8 and IL-1ra

Rationale

Low-grade inflammation and emphysema have been shown to be associated with an increased risk of lung cancer. However, the systemic inflammatory response in patients with emphysema is still unknown.

Objective

To compare the plasma cytokine profiles in two groups of current or former smokers without airway obstruction: a control group of individuals without computed tomography (CT) detected emphysema vs. a study group of individuals with CT detected emphysema.

Methods

Subjects underwent a chest CT, spirometry, and determination of EGF, IL-15, IL-1ra, IL-8, MCP-1, MIP-1β, TGFα, TNFα, and VEGF levels in plasma. Cytokine levels in each group were compared adjusting for confounding factors.

Results

160 current smokers and former smokers without airway obstruction participated in the study: 80 without emphysema and 80 subjects with emphysema. Adjusted group comparisons revealed significant reductions in EGF (−0.317, p = 0.01), IL-15 (−0.21, p = 0.01), IL-8 (−0.180, p = 0.02) and IL-1ra (−0.220, p = 0.03) in subjects with emphysema and normal spirometry.

Conclusions

Current or former smokers expressing a well-defined disease characteristic such as emphysema, has a specific plasma cytokine profile. This includes a decrease of cytokines mainly implicated in activation of apoptosis or decrease of immunosurveillance. This information should be taken into account when evaluated patients with tobacco respiratory diseases.     

Present state and possibilities for improvement of cancer prevention and early detection in the Osijek-Baranya county

Cancer morbidity and mortality are on a steady increase in Croatia. Technologic possibilities for appropriate management are available for four cancer sites, i.e. cancer of the breast, cervix uteri, colorectum and prostate, and include cancer prevention and early detection in individuals yet free from manifest signs of the disease. The magnitude of the problem, the experience acquired to date, health care personnel available, and additional resources required to launch a systematic program of early detection of the disease are presented. The program should be initially launched in a county with greatest experience in early detection of cancer, where health care service is ready to immediately start its implementation. The role of family physician, gynecologic service at primary health care level, and polyclinic-consultation hospital service in program implementation is described. The following three possible options for early detection of cancer are analyzed and proposed: minimal program (early detection every 3 years), medium program (the same individuals examined every 2 years), and optimal program proposed by the American Cancer Society and other national and international organizations.     

The presence of gap junctions during early Patella embryogenesis: An electron microscopical study

The presence of gap junctions has been examined up to the sixth cleavage in the early Patella embryo. Gap junctions are located all over the blastomere borders. In 2-, 4-, and 8-cell embryos they were also observed at peripheral contacts. The frequency and size of the gap junctions increase at the 32-cell stage. The structure of gap junctions is similar in all stages investigated with hexagonally arranged equal-sized particles (11 nm) having a constant center-to-center spacing (13.0 nm). At the 32-cell stage formation plaques were observed, indicating an increase of gap junctions.