Direct effects of serotonin and ketanserin on the functional morphology of embryonic chick skin in vitro

Summary Different organotypical culture methods are used to test the direct effects of serotonin and ketanserin, a S₂, α₁, and H₁ receptor antagonist in vascular tissue, on fibroblasts and epidermal cells of embryonic chick skin in vitro. From light microscopic and electron microscopic analyses, we learn that serotonin enhances keratinization and differentiation, whereas ketanserin reduces differentiation in comparison to the control cultures. Incorporation data of fragments cultured with [³H]thymidine show that ketanserin, within a dose range from 0.05 to 5 μg/ml, stimulates proliferation. Serotonin at a concentration of 10 μg/ml slightly slows down proliferation, whereas lower doses of 0.1 and 1 μg/ml result in tritium activities that do not differ from control cultures. This investigation was financially supported by the National Fund of Scientific Research, Belgium, 3.0022.87.     

Influence ofl-thyroxine,l-triiodothyronine,thyroid stimulating hormone,or estradiol on the cell kinetics of cultured mammary cancer cells

Summary We describe the in vitro influence of 3,5,3′-triiodo-l-thyronine (T₃),l-thyroxine (T₄), a thyroid-stimulating hormone (TSH), and/or estradiol (E₂: chosen as the control of the methodology) on the cell kinetics (cell distribution in the S+G₂+M phases) of mouse MXT and human MCF-7 mammary cancer cells. Experiments were performed by means of a cell image processor, analyzing MCF-7 or MXT cells that had been grown on glass cover slips and whose nuclei had been stained by the Feulgen reaction, which is selective and quantitative (stoichiometric) with respect to DNA. We show that T₃, T₄, and TSH at 0.01 μM dramatically stimulate the cell kinetics of the MXT mouse and the MCF-7 human mammary cancer cell lines. Indeed, the three hormones bring about a significant transient increase in the S+G₂+M fraction as does E₂. Furthermore, our data indicate that E₂ and TSH are antagonistic with regards to MXT or MCF-7 cell kinetics. This work is supported by grants awarded by the IRSIA and the Fonds de la Recherche Scientifique Médicale (FRSM, Belgium).     

Monitoring juvenile stocks of flatfish in the Wadden Sea and the coastal areas of the southeastern North Sea

Results are presented of an on-going monitoring program, started in 1970, of the demersal fish population in the Wadden Sea, Scheldt estuary, and along the continental coast between the Belgian-French border and Esbjerg. Particular attention is given to long-term trends in overall abundance and annual variations in spatial distribution of 0- and 1-group plaice and sole in relation to year-class strength and to variations in growth rate. Recruitment level in both plaice and sole appeared to be higher in the 1980s than in the 1970s. The most important nursery areas for plaice are the German Bight and the Wadden Sea, and the relative contributions of these areas to the total plaice stock in different years are relatively stable. In contrast, the most important nurseries for sole are along the continental coast, and the contribution of different parts of these nurseries vary considerably from year to year. Abundant year-classes of sole can originate from northern as well as from southern parts of the nurseries. Relations between survey results and year-class estimates from Virtual Population Analysis (VPA) for plaice are better compared to sole. No trends have been observed in mean length at age 0 and 1 during the years the surveys have been carried out. It is concluded that the quality of the continental coastal area and the Wadden Sea as nursery area for plaice and sole has not declined during the period of investigation. Presented at the VI International Wadden Sea Symposium (Biologische Anstalt Helgoland, Wattenmeerstation Sylt, D-2282 List, FRG, 1–4 November 1988)     

Thoracic traction on the trachea: mechanisms and magnitude

Both inspiratory increases and tonic thoracic traction (pull of the thorax) on the trachea [Ttx(tr)] have been shown to improve patency of the upper airway. To evaluate the origins and magnitude of Ttx(tr), we studied 15 anesthetized tracheotomized dogs. We divided the midcervical trachea and attached the thoracic stub to a strain gauge. Ttx(tr), esophageal pressure, and carinal displacement were observed during various conditions. These included unobstructed and obstructed spontaneous breathing, mechanical ventilation at various levels of positive end-expiratory pressure, and progressive hypercapnic stimulation. Observations during spontaneous breathing were performed before and after vagotomy. We found that inspiratory increases in Ttx(tr) were substantial, averaging 81 +/- 8 g force and increasing to 174 +/- 22 g force at an end-expiratory CO2 concentration of 10%. Ttx(tr) did not result simply from the pull of mediastinal and pulmonary structures transmitted through the carina. Changes in intrathoracic pressure acted independently to either draw the trachea into or push the trachea out of the thorax. Thus Ttx(tr) could be explained as the sum of mediastinal traction and force generated by changes in intrathoracic pressure.     

Modulation of IL-4-induced human IgE production in vitro by IFN-gamma and IL-5: the role of soluble CD23 (s-CD23)

IL-4 specifically induced IgE production by peripheral blood lymphocytes or by tonsil or spleen cells from healthy donors. IL-4-induced IgE synthesis was dependent on CD4+ T cells and monocytes and was blocked by IFN-gamma, IFN-alpha, and prostaglandin E-2 (PGE-2). These substances also inhibited IL-4-induced CD23 expression and subsequent release of soluble CD23 (s-CD23). In addition, IgE production was blocked by F(ab')2 fragments of an mAb against CD23. In contrast, IL-5 enhanced IL-4-induced IgE production, provided IL-4 was added at nonsaturating concentrations. This increase in IgE production correlated quantitatively with an enhanced release of s-CD23. Collectively, these results indicate that there is a correlation between s-CD23 release and IgE production. However, s-CD23 fractionated from supernatants of the lymphoblastoid cell line RPMI-8866 was ineffective in inducing IgE production in the absence of IL-4, but acted synergistically with suboptimal concentrations of IL-4. In addition, it is demonstrated that alloreactive T-cell clones produced varying concentrations of IL-4, IL-2, or IFN-gamma upon stimulation. Only supernatants of 2/4 of these T-cell clones induced a low degree of IgE synthesis, but in the presence of anti-IFN-gamma antibodies, all four supernatants induced a strong induction of IgE production. This IgE synthesis was blocked specifically by anti-IL-4 antibodies, indicating that IL-4 is the sole inducer of IgE synthesis. Our findings demonstrate that IL-4-induced IgE production involves complex interactions of T cells, B cells, and monocytes and is positively modulated by IL-5 and s-CD23 but down-regulated by IFN-gamma, IFN-alpha, and PGE-2, respectively.     

Nonvitellogenic female protein in Musca domestica

During vitellogenesis in Musca domestica, a major hemolymph protein, in addition to vitellogenin, appears preferentially in females. This protein is synthesized by the adult fat bodies, secreted into the hemolymph, and is not taken up by the ovaries during vitellogenesis. We have designated this protein nonvitellogenic female protein (NVFP). It is composed of only one type of polypeptide (M_r=70,000) and occurs in two different forms. Synthesis of NVFP is induced by a protein diet, attaining maximum concentrations in females at the middle of the gonotrophic cycle. In males its maximum concentration never surpasses 10% of the concentration in females. The quantitative variation of the NVFP is cyclic and coincident with the gonotrophic cycles of Musca domestica.