Characterisation of Hofbauer cells in first and second trimester placenta: incidence, phenotype, survival in vitro and motility.

Macrophages, known as Hofbauer cells, are most abundant in placental villous stroma in the first and second trimesters. Their functions are not well defined. We have used a combination of in situ and in vitro methods to characterise these cells. Lectin histochemistry and immunohistochemistry were used to identify macrophages in situ. The lectin from Maclura pomifera (MPA) was found to mark cells bearing the CD68 antigen with optimal specificity and selectivity. MPA staining was used to show that they increase in number from mid first to mid second trimester, becoming much less abundant at term. The cells are absent from mesenchymal villi, being associated primarily with villous stroma containing the prominent interstitial channels characteristic of immature intermediate villi. A mixed stromal cell isolate was studied in monolayer culture, including the use of time-lapse microscopy. Cells from first or second trimester tissue contained a subpopulation of about 14-17% of cells that exhibited a macrophage-like morphology and expressed CD68 as well as MPA-binding glycans. These cells were short-lived in monoculture, but could persist in vitro in association with a fibroblast layer for several weeks. They could switch rapidly from a macrophage-like to a fibroblastic morphology, were highly motile and associated in clusters that rapidly formed and dissipated over periods of a few hours. These data suggest that Hofbauer cells play a role in the maturation of mesenchymal into immature intermediate-type stroma. They may be important in the excavation of stromal channels. Their prolonged viability in mixed cultures suggests a paracrine relationship with resident fibroblasts. Their location and migratory behaviour predict an ability to move rapidly around the villous stroma, perhaps within the channel system, and to make transient contacts both with other macrophages and stromal cells.

Effects of continuous opioid receptor blockade on alcohol intake and up-regulation of opioid receptor subtype signalling in a genetic model of high alcohol drinking.

Effects of a continuous naloxone infusion via osmotic pumps on alcohol drinking and opioid receptor density and function in the high-drinking AA (Alko, Alcohol) rats were examined. AA rats were trained to drink 10% (v/v) ethanol in a 1-h limited access procedure and implanted with subcutaneous osmotic pumps delivering either saline, a low dose (0.3 mg/kg per hour), or a high dose (3.0 mg/kg per hour) of naloxone for 7 days. The pumps were then removed and alcohol, food and water intakes were measured for another 4 days. Compared with saline, both naloxone doses significantly suppressed 1-h alcohol intake during the 7-day infusion. The suppression was smaller than that by a bolus injection of the same daily dose 15 min before the session, although a complete blockade of morphine-induced antinociception was achieved even with the smaller naloxone infusion. Significant decreases were also seen in daily food and water intake during the first days, but they quickly returned to their previous baselines. After pump removal, rats of both naloxone-treated groups rapidly increased their alcohol drinking and reached the pretreatment baseline, while their food and water intakes significantly surpassed their baselines. Naloxone infusion at 3.0 mg/kg per hour for 7 days significantly decreased 24-h alcohol drinking without affecting alcohol preference. Twenty-four hours after pump removal, autoradiography with [3H]DAMGO, [3H]DPDPE and [3H]U-69,543 revealed an up-regulation of mu-, delta- and kappa-opioid receptor binding sites in many brain areas of these animals. This receptor up-regulation was functional, because receptor coupling to G-protein activation was enhanced by agonist ligands, as revealed by [35S]GTPgammaS autoradiography. A good correlation existed between ligand binding densities and G-protein activation for mu- and kappa-receptors in control and naloxone-treated brain sections. Furthermore, morphine-induced analgesia in a hot-plate test showed a leftward shift in the morphine dose-response curve after naloxone treatment. These results suggest that the usefulness of a chronic opioid antagonist dosing regime could be limited by nonspecific effects of the antagonist on ingestive behaviour, an up-regulation of opioid receptors with high antagonist doses, and the resulting supersensitivity to opioid agonists after the discontinuation of the treatment.

Cross-cultural aspects of fears in African children and adolescents.

The purpose of this study was to compare level and type of fears in Nigerian and Kenyan children using the Fear Survey Schedule for Children, Revised (FSSC-R; [Ollendick, T.H. (1983). Reliability and validity of the Revised Fear Survey Schedule for Children (FSSC-R). Behaviour Research and Therapy, 21, 685-692]). A total of 852 males and females between the ages of 8 and 17 were surveyed. Results indicated that Nigerian children reported significantly higher total fear than Kenyan children and that scores from both countries were higher than those found in the United States, Australia and China. This suggests that the cultures of Kenya and Nigeria may share a common variable that makes reporting of fears greater than that reported by children of other world cultures. In addition, Christian children in both countries reported higher levels of fear on several factors than Muslim children, indicating that Islamic beliefs may encourage children to report less fear or to deal with their fears better than Christian beliefs. Finally, children between the ages of 8 and 12 reported greater fear of the unknown than children between 13 and 17 years of age. Overall, these findings suggest that important cultural, religious and age differences exist for levels of childhood fears reported in Nigeria and Kenya.