Effects of 17alpha-methyltestosterone on sexually dimorphic characters in the weakly discharging electric fish, Brienomyrus niger (Günther, 1866) (Mormyridae): electric organ discharge, ventral body wall indentation, and anal-Fin ray bone expansion

Adult males of African weakly discharging electric fish (family: Mormyridae) are distinguished from juveniles and adult females by a dorsally directed indentation of the posterior ventral body wall and by massive bone expansion of the bases of a select number of anal-fin rays. These sexually dimorphic structures seem to facilitate the anal-fin reflex that is displayed during courtship when the male envelopes its anal fin around the female's to form a common spawning pouch. Expanded bone could provide additional surface for muscle attachment and thus assist in part with the courtship sequence. Based on the fact that the expression of the male sexually dimorphic electric organ discharge (EOD) is under androgen control, and that the female EOD can be masculinized through testosterone administration, we hypothesized that androgens should also drive anal-fin ray bone expansion in male mormyrids and equally effect male-like changes in treated juveniles and adult females. Exogenous androgen treatment (17alpha-methyltestosterone) of adult female Brienomyrus niger resulted in a male-like EOD, and male-typical structural transformations (body wall indentation and anal-fin ray bone expansion). Some of these changes were immediate and receded following hormone withdrawal (EOD), while others developed more slowly and were apparently permanent (indentation and bone formation). 17alpha-Methyltestosterone administration affected only those targets in females that are normally involved in the male's reproductive behavior, i.e., its courtship signal (EOD) and two morphological features (body-wall indentation and bone expansion). Rays of the dorsal or caudal fins were never affected.

Suppression of apoptosis in COLO 205 cells by the phorbol ester TPA may be mediated by the PKC isoenzyme alpha

Apoptosis induced by an antibody to CD95/APO-1/FAS in the colon carcinoma cells COLO 205 and HT-29 is suppressed by the phorbol ester TPA. Inhibition is much more effective in COLO 205 than in HT-29 cells. The TPA effect is abrogated by the protein kinase C (PKC)-specific inhibitor Go6983 indicating a role of PKC in this process. Bryostatin 1, unlike TPA, is unable to suppress apoptosis, but inhibits the TPA-induced suppression of apoptosis. TPA also inhibits indomethacin-induced apoptosis in COLO 205 cells. COLO 205 and HT-29 cells contain the PKC isoenzymes alpha, beta(II) delta, epsilon, eta, mu and zeta. Expression and activity of PKC alpha are at least 5 times higher in COLO 205 than in HT-29 cells. This correlates with the fact that inhibition of CD95-mediated apoptosis by TPA is more prominent in COLO 205 than in HT-29 cells. Thus, these findings suggest that PKC alpha has an important role in the TPA-induced inhibition of apoptosis.

Interactions between colour and motion in image segmentation

BACKGROUND

. An important early stage in visual processing is image segmentation, in which similar regions are grouped together and segregated from dissimilar regions, so that distinct objects ultimately may be located and recognized. In the natural world, objects are simultaneously characterized by colour, motion, texture and other visual attributes. How does the human visual system combine these attributes to segment the image? Although colour and motion information are conveyed by distinct functional streams from retina to visual cortex, there is increasing evidence for early and substantial cross-talk between the streams. Here, we explore psychophysical evidence for interactions between colour and motion in image segmentation.

RESULTS

. Observers performed forced-choice segmentation tasks on random-dot stimuli. The dots in the vertical target figure were distinguished from the background dots by a different distribution of speeds or colours. To explore interactions between motion and colour segmentation, we added motion noise to the colour signal (or vice versa) by assigning all dots speeds (or colours) drawn from one of several noise distributions. Motion noise severely affects segmentation by colour. Motion noise defined by a broad distribution of speeds degrades colour segmentation, but a two-speed motion distribution (half moving up, half moving down) facilitates colour segmentation. Control experiments prove that the facilitatory effect is not caused by integrating colour information over different frames, nor can it be explained by probability summation over the two planes of moving dots. Colour noise also affects motion segmentation, but under a more restricted range of conditions, and not in a facilitatory way.

CONCLUSIONS

. Colour and motion information interact at early stages during image segmentation, before decisions based on either cue in isolation are made. The robust bipolar effects of motion information on segmentation by colour indicate that the establishment of motion-defined surfaces takes primacy, and that such surfaces constitute important primitives for further processing.

Comparison of adherent lymphokine-activated killer (a-lak) cells generated by IL-2 and IL-7 - cellular modifications induced by IL-7

At present, the clinical application of plastic-adherent-lymphokine-activated killer (A-LAK) cells shows limited success in the immunotherapy of patients with advanced cancer because of a low responder rate, severe side effects and failures in yielding sufficient numbers of cells for adoptive transfers. Since interleukin-7 (IL-7) is able to induce LAK activity independently of IL-2, we investigated the ability of IL-7 to improve the yield and the properties of A-LAK cells. A-LAK cells from 7 healthy donors generated in the presence of IL-2, IL-7 or combinations of IL-2 plus IL-7 (each 1000 U/ml) were compared with regard to plastic adherence, expansion rate, immunophenotype, cytokine secretion and cytotoxicity against malignant melanoma cells and non-malignant target cells. Our results demonstrate that A-LAK cells generated by a simultaneous stimulation of IL-2 plus IL-7 displayed a significantly higher expansion rate (10.7-fold vs. 9.0-fold), but showed no difference in the cytolytic activity compared to A-LAK cells generated by IL-2 alone. A-LAK cells generated by IL-7 alone demonstrated a low expansion rate (1.1-fold vs. 8.8-fold), and decreased in other properties like plastic adherence, CD56(+)/CD3(+) cell-ratio and cytolytic activity compared to A-LAK cells generated by IL-2 alone. A-LAK cells generated by IL-7 or a sequential stimulation of IL-2 and IL-7, on the other hand, exhibited a more selective cytotoxicity for malignant melanoma cells compared to the non-malignant keratinocyte target cell line (HaCaT) and normal fibroblasts. A sequential replacement of LL-2 by IL-7 might help to reduce the severe side effects of IL-2. In vivo experiments are necessary to evaluate the potential value of IL-7 in adoptive immunotherapy.

EVA Suit 2000: a joint European/Russian space suit design

A feasibility study in 1992 showed the benefits of a common European Russian space suit development, EVA Suit 2000, replacing the Russian space suit Orlan-DMA and the planned European Hermes EVA space suit at the turn of the century. This EVA Suit 2000 is a joint development initiated by the European Space Agency (ESA) and the Russian Space Agency (RKA). The main objectives of this development program are: first utilization aboard the Russian Space Station MIR-2; performance improvement with respect to current operational suits; development cost reduction. Russian experience gained with the present extravehicular activity (EVA) suit on the MIR Space Station and extensive application of European Technologies will be needed to achieve these ambitious goals. This paper presents the current status of the development activities, the space suit system design and concentrates in more detail on life support aspects. Specific subjects addressed will include the overall life support conceptual architecture, design features, crew comfort and operational considerations.

Fibronectin and fibronectin-receptors of the integrin type in normal colon mucosa, adenoma and carcinoma

Integrin alpha 3, alpha 4, alpha 5, and alpha v subunits heterodimerize with beta 1 and beta 3 chains to form functional fibronectin (FN) receptors. Two of them, alpha 4 beta 1 and alpha 5 beta 1, recognize FN as the only matrix molecule. Additional binding of laminin, collagen, and entactin is achieved by alpha 3 beta 1 while alpha v beta 1 and alpha v beta 3 also bind vitronectin. We investigated immunohistochemically the tissue distribution of FN and the expression of FN receptor alpha- and beta-chains in 20 normal colon tissues, 10 adenomas, 90 carcinomas, and 10 liver metastases derived thereof. In normal and adenomatous colon tissues FN was detected in association with reticular and fibrillar structures of the gut wall. The tumor stroma of carcinomas and liver metastases contained abnormally high amounts of FN which were detectable as chaotic deposits. Normal and adenomatous mucosa were alpha 3(+), alpha 4(-), alpha 5(-), alpha v(+/-), beta 1(+), beta 3(-) indicating that only promiscuous FN receptors were expressed. 21 of 90 carcinomas had a focal or complete loss of alpha 3 which was more often found in Dukes C/D tumors (p<0.005). The liver metastases more often had lower levels of alpha 3 expression compared to the primary tumor. The alpha v-expression was inconsistent and often weak. These losses of FN receptor constituents in carcinomas were not paralleled by any noticeable differences in stromal content or distribution pattern of FN, Enhanced expression/induction of FN receptors was found in only 2 of 90 carcinomas which focally neo-expressed the alpha 5-chain. This aberrant alpha 5 expression, however, was flow cytometrically found in 3/4 colon carcinoma cell lines which otherwise had receptor profiles corresponding to the in situ situation. FN-adherence of cell lines was variable. Anti-alpha 3 had no blocking effect on FN adherence of SW480, SW620, and COLO 205 but a minor effect on FN binding of HT-29. Anti-alpha 5 blocked FN adhesion whenever alpha 5 was expressed. Anti-av had no blocking effect while anti-beta 1 reduced FN adherence of all cell lines. The net biological effect(s) of aberrant expression of integrin type FN receptors in colon carcinomas is unpredictable as yet.

The effects of androgens and estrogen on the external morphology and electric organ discharge waveform of Gnathonemus petersii (Mormyridae, Teleostei)

The effects of androgens and estrogen on the external morphology and electric organ discharge (EOD) waveform in Gnathonemus petersii, a weakly discharging electric fish, were investigated. Following preimplant data collection, juvenile and adult fish were gonadectomized and implanted with silastic capsules containing either high or low doses of testosterone (T), dihydrotestosterone (DHT), estradiol-17 beta (E2), or cholesterol. One group of fish was treated with high doses of DHT + E2. Radioimmunoassays revealed that low-dose implants resulted in plasma T levels comparable to and high-dose implants about sixfold greater than those found in adult males imported during breeding season. High-dose E2 implants resulted in higher plasma E2 levels in adults than those in juveniles. At either dose, both androgens induced male-like indentations in the dorsal margin of the anal fin of juveniles and adult females by 4 weeks postimplant. Both low and high doses of T decreased the peak power spectrum frequency (PPSF) of Fourier transformations of EODs and increased the durations of phases 2 and 3 of the EOD in juveniles and adults, but the high doses caused more rapid and profound effects. The two doses of T caused opposite effects on the durations of phases 1 and 4 juveniles. The low dose of T decreased the durations of phases 1 and 4, while the high dose increased them. In adults, the high dose of T increased the duration of phase 1, but had inconsistent effects on the duration of phase 4. Total EOD durations were increased by both doses of T in juveniles, while adults showed inconsistent effects possibly due to individual variability in hormone sensitivity. Compared to T, DHT exerted similar, but less dramatic effects on all measures, but only at high doses. E2 significantly increased adult PPSFs, the first such finding in a mormyrid species. E2 had no effects on juvenile PPSFs, or on adult or juvenile EOD phase durations. The effects of DHT + E2 on PPSF and phases 2 and 3 were similar to those of DHT alone. These findings demonstrate quantifiable steroid-dependent plasticity in the durations of individual phases of EODs in an electric fish and are the first to show that the external morphology in Gnathonemus petersii is androgen-dependent. The results are discussed with regard to methodological considerations and hormone studies involving sex differences in EODs reported for this and other species.

Production and characterization of monoclonal antibodies to the glycosyl phosphatidylinositol-anchored lymphocyte differentiation antigen ecto-5'-nucleotidase (CD73)

A panel of monoclonal antibodies to the 69 kDa glycosyl phosphatidylinositol anchored lymphocyte differentiation antigen ecto-5'-nucleotidase (ecto-5'-NT, CD73) was produced using highly purified human placental 5'-NT as immunogen. Antibodies 1E9.28.1 and 7G2.2.11 inhibit soluble placental 5'-NT activity and recognize lymphocyte CD73 in indirect immunofluorescence and immunoprecipitation assays. In addition, 1E9.28.1 induces vigorous T cell proliferation in the presence of submitogenic doses of phorbol myristate and F(ab')2 goat anti-mouse Ig. Both antibodies can be used to purify the three major forms of placental 5'-NT by affinity chromatography. By two-color immunofluorescence, CD73 was found to be expressed on 19 +/- 5% of CD3+, 11 +/- 4% of CD4+, 51 +/- 14% of CD8+, 25 +/- 8% of CD28+, 15 +/- 5% of CD29+, 27 +/- 7% of CD45RA+, and 70 +/- 6% of CD19+ lymphocytes. Within T cells, CD73 expression is restricted to the CD28+ subset. Thus, CD73 is found on subsets of both T and B lymphocytes, with the highest expression on B cells and CD8+ T cells. In sections of hyperplastic tonsil, CD73 expression is restricted to the small lymphocytes of the follicular mantle zone, a small subset of extrafollicular lymphocytes situated within the epithelium of the tonsillar crypt, and to follicular dendritic cells within the lower part of the "light-zone." CD73 is also detected on subsets of endothelial cells of capillaries and venules and the basal layer of non-keratinizing squamous epithelium and transitional cell type mucosa of many tissues. Given the tissue distribution of CD73, along with its glycosyl phosphatidylinositol membrane anchoring and the observation that some CD73 antibodies are mitogenic, we propose that this interesting antigen may play a role in cell activation, lymphocyte homing, and/or cell adhesion.

Evidence that in vitro adherence of Klebsiella pneumoniae to ciliated hamster tracheal cells is mediated by type 1 fimbriae

Clinical isolates of fimbriated and nonfimbriated Klebsiella pneumoniae were examined for the ability to adhere to hamster tracheal cells cultured in vitro. Fimbriated-phase K. pneumoniae adhered preferentially to ciliated cells, whereas nonfimbriated-phase organisms were not adherent. The adherence was inhibited by D-mannose but not D-glucose, suggesting that type 1 fimbriae serve as the adhesin in the attachment process.

Testosterone changes the electric organ discharge and external morphology of the mormyrid fish, Gnathonemus petersii (Mormyriformes)

Effects of silastic and pellet methyltestosterone implants on the waveform of the electric organ discharge of the weakly electric African mormyrid, Gnathonemus petersii, were investigated. Within seven days of implantation, the duration of the discharge increased dramatically while the associated peak power frequency of the Fourier spectrum decreased in all treated fish. By day 35, hormone-treated fish exhibited up to five-fold increases in EOD duration, as well as multiple discharges and variations in the shape of the positive phase of the discharge. Testosterone treatment also changed body morphology, making immature and adult female fish resemble adult males.

Caries prevalence in Icelandic children in 1970 and 1983

In the autumn of 1983 a clinical survey was carried out on 756 children aged 6-14 yr, residing in three non-fluoridated communities in Iceland. The aim of the survey was to assess what changes, if any, in caries prevalence may have taken place as a result of the provision of free dental restorative services for these children since 1974. The 1983 prevalence data were compared with data obtained from a caries survey conducted in 1970 in the same areas in Iceland. The same examiner performed all examinations in both studies. Although considerable increase was noted in number of filled teeth with a corresponding decrease in carious and missing teeth, a statistically significant change in caries prevalence, (dft, dfs, DMFT, DMFS) did not manifest itself. The dfs and DMFS in 1983 was 8.9 and 9.5, respectively, compared to 8.5 and 10.4 in 1970. Over 90% of the toothpaste used in Iceland during the 1970's contained fluoride. The children in the three study areas had not been provided with any public preventive programs.

Locomotor and electric displays associated with electrolocation during exploratory behavior in mormyrid fish

In the presence of a novel stimulus such as an aluminum or a plastic rod mormyrid fish (Marcusenius cyprinoides and Gnathonemus petersii) exhibit characteristic motor probing acts (PMAs): 'chin probing', 'radial' and 'lateral va-et-vient', 'lateral probing', 'tangential probing', and 'stationary probing'. During the display of these PMAs the fish maintain characteristic probing distances from the object which were 4.5 cm for the metal and 2.5-3.7 cm for the plastic stimulus. G. petersii with their electric organ rendered inoperative ('silent fish') no longer exhibited 'radial' and 'lateral va-et-vient'. Regardless of the nature of the stimulus the probing distances were shorter in 'silent' fish and ranged from 1.8 to 2.6 cm. During the display of PMAs intact fish changed their variable electric organ discharge rate to a unique and stable, regularized rate, with the interdischarge interval maintained at 28-30 ms. The fish's electric and non-electric (motor) probing behavior in the presence of novel objects (and following their removal during phantom PMAs) is discussed in light of theories on exploratory behavior.

A renal lesion in ankylosing spondylitis

2 patients with ankylosing spondylitis (A Sp) were found to have renal lesions similar to those seen in IgA nephropathy. In 1 patient the changes were extremely severe and progressive and in the other they were mild. Vascular changes were also noted in 1 patient. The findings suggest an immune complex mediated glomerulonephritis and support an earlier report that there may be a specific renal lesion in patients with A Sp. The significance of IgA deposition in the mesangium, and of an increase in the serum levels of IgA in some patients with A Sp is unclear.

Electric signals and schooling behavior in a weakly electric fish, Marcusenius cyprinoides L. (Mormyriformes)

Field recordings of electric organ discharges and catches of Marcusenius cyprinoides showed that these electric fish form groups and move about in schools. The role electric organ discharges in group cohesion was investigated by comparing interactions in groups of intact and operated, electrically silent fish. The absence of electric organ dischares reduced locomotor activity and resulted in the disappearance of two behaviors: parallel lineup and single file swimming. Electric signals are considered part of a schooling mechanism that aids the fish in maintaining group cohesion in their turbid enviornment and during migration at night.

Electric organ discharges of the weakly electric fish Gymnarchus niloticus (Mormyriformes) in its natural habitat

Electric organ discharges (EODs) of Gymnarchus niloticus in its natural habitat (Chari River, Chad Basin) and accompanying ecological data (pH, conductivity, temperature, turbidity, O2 dissolved) were recorded. The EOD frequencies ranged from 204 to 313 Hz (day) and 196-326 Hz (night). In social swimming the range of interfish EOD frequency differences was from 4 to 82 Hz. The EOD frequency seems to decrease with the age of the fish.

[Dental instrument as foreign body in the air-passage]

A case report on a Kerr-broach aspirated to the left bronchial tree is presented. The broach was removed with difficulties using bronchoscope and forceps. The use of rubber dam is advocated in endodontic therapy. A scheme to handle foreign bodies in the bronchial tree is outlined involving immediate X-ray and removal by an experienced endoscopist.