Primary author of several recent studies involving di-n-butyl phthalate (DBP) and linuron (L) discusses his findings and what they mean for understanding human development.
Over the last ten years, US researchers have observed a marked increase in some male reproductive disorders, including undescended testicles, increased instances of testicular cancer, and decreased sperm count. In the last 20 years the rates for testicular cancer have grown almost five-fold in Denmark, yet neighboring Finland has not experienced such a dramatic increase. In an effort to explain this phenomenon, scientists have hypothesized that these human male reproductive deficits may have a common origin: a disturbance in the level of androgen and other critical hormones during fetal development. The results from tests with laboratory animals may help scientists better understand the effect of fetal exposure to certain chemicals has on male reproduction abilities later in life.
Paul M.D. Foster, Ph.D., of the National Institutes of Environmental Sciences, Research Triangle Park, NC, and his colleagues have recently co-authored a series of journal articles examining how fetal exposure to two common environmental agents affects the reproductive capabilities of some laboratory animals. Dr. Foster will be discussing their research during a presentation entitled, "Disruption of Male Reproductive Development by Antiandrogens" during the 55th Annual Meeting of the American Association for Clinical Chemistry (AACC), being held at the Pennsylvania Convention Center, Philadelphia, PA, July 20-24, 2003. More than 16,000 attendees are expected.
Presently, studies of antiandrogen and the male reproductive system are confined to experimental animals, since human studies exposing pregnant women to large quantities of these chemical agents would be inappropriate. Additionally, common human birth defects are difficult to track and definitively establish cause and effect.
Dr. Foster does not believe that the findings of these animal studies should be cause for alarm. While researchers do not know at what dose level exposure to these chemicals might produce effects in humans, they know that in animals, the dose levels that produce the adverse changes are significantly higher than the levels that have been measured in ongoing human studies.
He does believe that this research, and the similar efforts of other research institutions, will expand the effort to determine how environmental and pharmaceutical antiandrogens may impact on human development. The effects of antiandrogen exposure may not be uniform for any population group. This suggests that research in this field should be linked linked to the ongoing effort to map critical developmental signaling pathways that determine why only some react to these selected agents.
Donna Krupa | EurekAlert!
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The pyrenoid is a carbon-fixing liquid droplet
22.09.2017 | Max-Planck-Institut für Biochemie
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
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Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
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Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
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