Key stages in mammary gland development: The mammary end bud as a motile organ

In the rodent, epithelial end buds define the tips of elongating mammary ducts. These highly motile structures undergo repeated dichotomous branching as they aggressively advance through fatty stroma and, turning to avoid other ducts, they finally cease growth leaving behind the open, tree-like framework on which secretory alveoli develop during pregnancy. This review identifies the motility of end buds as a unique developmental marker that represents the successful integration of systemic and local mammotrophic influences, and covers relevant advances in ductal growth regulation, extracellular matrix (ECM) remodeling, and cell adhesion in the inner end bud. An unexpected growth-promoting synergy between insulin-like growth factor-1 and progesterone, in which ducts elongate without forming new end buds, is described as well as evidence strongly supporting self-inhibition of ductal elongation by end-bud-secreted transforming growth factor-β acting on stromal targets. The influence of the matrix metalloproteinase ECM-remodeling enzymes, notably matrix metalloproteinase-2, on end bud growth is discussed in the broader context of enzymes that regulate the polysaccharide-rich glycosaminoglycan elements of the ECM. Finally, a critical, motility-enabling role for the cellular architecture of the end bud is identified and the contribution of cadherins, the netrin/neogenin system, and ErbB2 to the structure and motility of end buds is discussed

Endogenous L-glutamate transport in oocytes of Xenopus laevis

The existence of an endogenous Na+-glutamate cotransporter in the oocytes of Xenopus laevis is demonstrated. The transporter does not accept D-glutamate as substrate. The dependence on substrate displays two saturating components with low (K1/2 = 9 mM) and high (K1/2 = 0.35 microM) affinities for L-glutamate. The dependence on external Na+ exhibits a saturating component with a K1/2 value of about 5 mM and a component that has not saturated up to 110 mM Na+. In voltage-clamped oocytes, it is possible to demonstrate that Na+-dependent L-glutamate transport is directly coupled to countertransport of Rb+. The analysis of the voltage dependence of the Na+,K+-dependent L-glutamate uptake suggests that positive charges are moved inwardly during the transport cycle

Click or strike: Realistic versus standard game controls in violent video games and their effects on aggression

The motion detection technology used in innovative game controlling devices like the Nintendo Wii-Remote® provides experiences of realistic and immersive game play. In the present study (N=62) it was tested whether this technology may also provoke stronger aggression-related effects than standard forms of interaction (i.e., keyboard and mouse). With the aid of a gesture recognition algorithm, a violent action role-playing game was developed to compare different modes of interaction within an otherwise identical game environment. In the Embodied Gestures condition participants performed realistic striking movements that caused the virtual character to attack and kill other in-game characters with a club or sword. In the Standard Interaction condition attacks resulted from simple mouse clicks. After the game session, participants showed a similar increase in negative feelings in both groups. When provided with ambiguous scenarios, however, participants in the Embodied Gestures condition tended to show more hostile cognitions (i.e., anger) than the Standard Interaction group. Results further corroborate the complexity of aggression-related effects in violent video games, especially with respect to situational factors like realistic game controls

Workload during cardiopulmonary resuscitation

Objectives: Lay resuscitation is crucial for the survival of the patients with out-of-hospital cardiac arrest. Therefore, lay CPR should be a basic skill for everyone. With the growing proportion of retired people in the Western societies, CPR performed by people with preexisting diseases and at risk of cardiac events is expected to grow. There is little knowledge about the workload during CPR and the minimum workload capacity of the rescuer. Methods: Pulse frequency, oxygen uptake, and CO2 elimination were measured by telemetry, while CPR was performed using a manikin with digital equipment for the standardization of the procedure. The same parameters were measured during a standard exercise testing protocol (spiroergometry) on a bicycle to analyze the aerobic endurance range of the participants. Data from the resuscitation protocols were correlated with those from spiroergometry to establish a simple standard investigation procedure to check people at risk and to give minimum requirements to perform CPR in Watts/kg. The study consisted of two parts: 1 (n=16) explored minimal workload cutoffs for the rescuer using the 1995 recommendations and 2 (n=14) tested the latest 2010 guidelines to compare both recommendations. Results: When tested according to the 1995 guidelines, heart frequency of rescuers increased from 83.0bpm (±11.3) at rest to 109.9bpm (±12.6; P=0.0004). The newer 2010 guidelines increased the workload marginally more (n.s.). Conclusion: CPR can be performed by healthy people within the range of aerobic endurance. The minimal requirements for trainings are 1.6-1.8W/kg body weight in standard cycling ergometry. People at risk should be trained very careful. Since there is no significant lower workload when following the 1995 recommendations, people at risk should be trained according to the latest recommendations. In the case of a real resuscitation, such trained individuals must additionally take into account any symptoms

Comparison of a Na⁺/D-glucose cotransporter from rat intestine expressed in oocytes of Xenopus laevis with the endogenous cotransporter

Epithelial Na+/D-glucose cotransport was incorporated into the plasma membrane of Xenopus oocytes after microinjection of poly(A)+-mRNA from rat intestine tissue and was detected by measurements of uptake of [14C]AMG (methyl alpha-D-glucopyranoside). In mRNA-injected oocytes, the rate of AMG uptake exceeds the rate of endogenous Na+/AMG cotransport by a factor of up to 30. It is demonstrated that the additionally expressed transport differs qualitatively from the endogenous transport with respect to several parameters which is a prerequisite for the demonstration of expression of a foreign transporter: (1) The expressed system is more sensitive to external glucose or AMG and to the specific inhibitor phlorizin, (2) it is less sensitive to external Na+ and to changes in membrane potential, and (3) it is susceptible to inhibition by monoclonal antibodies, known to bind specifically to Na+/glucose cotransporters and to modulate the cotransport in kidney and intestine. The use of the antibodies allows one to distinguish between endogenous Na+/AMG cotransport and foreign cotransport expressed by injection of foreign mRNA. The expression of the foreign transport leads to transport rates that are high enough to detect the electrical current generated by the Na+/glucose cotransport. This allows future characterization of the cotransport system under voltage-clamp conditions by analyzing membrane current

The Allure of the Forbidden: Breaking Taboos, Frustration, and Attraction to Violent Video Games

Although people typically avoid engaging in antisocial or taboo behaviors, such as cheating and stealing, they may succumb in order to maximize their personal benefit. Moreover, they may be frustrated when the chance to commit a taboo behavior is withdrawn. The present study tested whether the desire to commit a taboo behavior, and the frustration from being denied such an opportunity, increases attraction to violent video games. Playing violent games allegedly offers an outlet for aggression prompted by frustration. In two experiments, some participants had no chance to commit a taboo behavior (cheating in Experiment 1, stealing in Experiment 2), others had a chance to commit a taboo behavior, and others had a withdrawn chance to commit a taboo behavior. Those in the latter group were most attracted to violent video games. Withdrawing the chance for participants to commit a taboo behavior increased their frustration, which in turn increased their attraction to violent video games