http://www.rxpgnews.com/ Medical News and Information Thu, 25 Oct 2007 07:48:36 PST en-us http://www.rxpgnews.com/cytology/How_cells_adhere_so_firmly_to_blood_vessel_walls_5127_5127.shtml Cytology Blood is the universal means with which different types of cells are transported in our bodies. Its movement is determined by hydrodynamic forces. The cells anchor themselves to the walls of the blood vessels in the target tissue with the aid of special adhesive molecules, which are also called receptors. In many cases these receptors are grouped in the cell surface in nanometer-sized patches. The adhesion process is based on the key and lock principle: as a rule, an adhesion molecule only bonds with specific partners. This guarantees that the cells are only brought to a halt where they are to fulfill their biological function. Sat, 04 Nov 2006 20:57:00 PST http://www.rxpgnews.com/cytology/How_cells_adhere_so_firmly_to_blood_vessel_walls_5127_5127.shtml http://www.rxpgnews.com/cytology/New_Insight_into_Cell_Division_5112_5112.shtml Cytology When cells divide, control mechanisms ensure that the genetic material, in other words the chromosomes, is correctly distributed to the daughter cells. Researchers at the Max Planck Institute for Molecular Genetics in Berlin have now explained the molecular principles of these control processes. The so-called checkpoint kinases, i.e. the enzymes which perform this controlling, are not directly associated only with the chromosomes, as was previously assumed to be the case. On the contrary, they interact with a different category of proteins which are involved in the development of the cell division spindle. This finding is highly significant, since incorrect distribution of the chromosomes can lead to abnormalities and diseases such as cancer. The new understanding of this process will in turn promote a better understanding of the molecular principles of the development of cancer (Science, October 27, 2006). Sun, 29 Oct 2006 21:36:00 PST http://www.rxpgnews.com/cytology/New_Insight_into_Cell_Division_5112_5112.shtml http://www.rxpgnews.com/cytology/New_method_for_the_controlled_initiation_of_membra_5084_5084.shtml Cytology The process of membrane fusion is essential for the structure and dynamics of all cells in our bodies. Fusion is indispensable for intracellular vesicle traffic, which sustains the compartmental organisation of cells. Likewise, membrane fusion is the basic molecular process that controls the communication between cells via the secretion of hormones, neurotransmitters, and growth factors. Furthermore, fusion processes are also crucial for the interactions between our cells and various pathogens such as viruses and bacteria. However, in spite of the ubiquity of membrane fusion, many aspects of this process have remained rather controversial. This situation reflects the absence of well-defined protocols by which one can induce fusion in a controlled manner and subsequently study its dynamics with high temporal resolution. Thu, 19 Oct 2006 23:39:00 PST http://www.rxpgnews.com/cytology/New_method_for_the_controlled_initiation_of_membra_5084_5084.shtml http://www.rxpgnews.com/cytology/CPK3_and_CPK6_function_as_ion_channel_regulators_i_5055_5055.shtml Cytology When water is scarce, plants synthesize a hormone that facilitates conservation by closing stomatal pores on their leaves. Each pore is surrounded by a pair of guard cells that control stomatal aperture in response to various stimuli, including the drought-triggered hormone called abscisic acid (ABA). ABA signaling increases calcium levels in guard cells; calcium in turn acts on a variety of channels that regulate the transport of ions across the cell membranes. As both positively and negatively charged ions (called anions) cross the membrane, turgor pressure drops and stomata close. Wed, 11 Oct 2006 05:21:00 PST http://www.rxpgnews.com/cytology/CPK3_and_CPK6_function_as_ion_channel_regulators_i_5055_5055.shtml http://www.rxpgnews.com/cytology/Disrupted_Intercellular_Communication_Causes_a_Dis_4956_4956.shtml Cytology Before a fertilized egg begins the repeated rounds of cell division that turn the single cell into a proliferating, streaming, differentiating mass of cells, its fate may already be sealed. Inherited mutations in genes involved in segregating and sorting embryonic cells can result in serious abnormalities in body patterning and appear to underlie an inherited X-linked disorder (so-called because the mutated genes lie on the X chromosome) called craniofrontonasal syndrome (CFNS). X-linked disorders tend to affect males more severely than females, because boys inherit just one X chromosome while girls inherit two: if one gene is defective, the other can fill in. CFNS is a rare departure from this pattern, with females exhibiting the most severe symptoms. This disfiguring disorder is characterized by a range of skull aberrations, including facial asymmetry, widely spaced eyes, and abnormal head shape, as well as polydactyly and fused digits. Wed, 13 Sep 2006 09:50:00 PST http://www.rxpgnews.com/cytology/Disrupted_Intercellular_Communication_Causes_a_Dis_4956_4956.shtml http://www.rxpgnews.com/cytology/Sharing_Responsibility_for_Clathrin_Coat_Assembly_4848_4848.shtml Cytology Membranes protect cells from extracellular insults, but in so doing also block entry to nutrients and other essential molecules. One way cells circumvent this problem is by selectively binding such molecules to receptors on the membrane, then pulling the whole lot into the cell and packaging them into vesicles. Clathrin molecules—three-pronged pinwheel-shaped proteins—form an elaborate lattice coat around the vesicles, which ultimately bud off from the membrane and transport their cargo to their cellular destination. Wed, 16 Aug 2006 08:58:00 PST http://www.rxpgnews.com/cytology/Sharing_Responsibility_for_Clathrin_Coat_Assembly_4848_4848.shtml http://www.rxpgnews.com/cytology/Understanding_the_process_of_AIF_release_following_4775_4775.shtml Cytology Scientists at St. Jude Children's Research Hospital have demonstrated that a key event during apoptosis (cell suicide) occurs as a single, quick event, rather than as a step-by-step process. Apoptosis eliminates extraneous cells from the developing body; and disposes of cells that sustain irreparable harm to their DNA or are infected with microorganisms. The researchers photographed individual cells undergoing that process, allowing investigators to observe the release of certain proteins from pores in the membranes of mitochondria. These cellular structures contain enzymes that extract energy from food molecules, and the space within the membrane surrounding them holds a variety of proteins that are released during apoptosis. Wed, 02 Aug 2006 13:05:00 PST http://www.rxpgnews.com/cytology/Understanding_the_process_of_AIF_release_following_4775_4775.shtml http://www.rxpgnews.com/cytology/Researchers_discover_new_cell_structures_4580_4580.shtml Cytology Carnegie Mellon University researchers Kris Noel Dahl and Mohammad F. Islam have made a new breakthrough for children suffering from an extremely rare disease that accelerates the aging process by about seven times the normal rate. Dahl, an assistant professor of chemical and biomedical engineering at Carnegie Mellon, said her work with researchers at the National Cancer Institute of the National Institutes of Health (NIH), the John Hopkins University School of Medicine and the University of Pennsylvania reveals that children suffering from Hutchinson-Gilford Progeria Syndrome (HGPS) have an excessively stiff shell of proteins. Fri, 30 Jun 2006 01:32:00 PST http://www.rxpgnews.com/cytology/Researchers_discover_new_cell_structures_4580_4580.shtml http://www.rxpgnews.com/cytology/Cilia_also_contribute_to_cellular_response_to_exte_4228_4228.shtml Cytology By studying microscopic hairs called cilia on algae, researchers at UT Southwestern Medical Center have found that an internal structure that helps build cilia is also responsible for a cell's response to external signals. Thu, 04 May 2006 23:13:00 PST http://www.rxpgnews.com/cytology/Cilia_also_contribute_to_cellular_response_to_exte_4228_4228.shtml http://www.rxpgnews.com/cytology/A_riboswitch_might_sense_magnesium_levels_in_the_c_4001_4001.shtml Cytology Magnesium, essential for energy-production and structural integrity, is critical to cell survival. Researchers have now found that cells use specialized segments of RNA called riboswitches to ensure that there is an adequate supply of the mineral. The newly described riboswitch can both sense magnesium levels and respond directly by regulating production of a magnesium transport protein. Wed, 12 Apr 2006 13:07:00 PST http://www.rxpgnews.com/cytology/A_riboswitch_might_sense_magnesium_levels_in_the_c_4001_4001.shtml