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Topic: Bystander effect

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	Don't Just Stand There - Do Something
		When a violent incident or emergency occurs, the Bystander Effect is not a mere academic concept.
		In an unpublicized case last summer, seven young men robbed and knifed the 16-year old nephew of a Canada Safety Council staff member, who happened to be walking through a downtown park in a major Canadian city.
		After examining other instances of bystander intervention and non-intervention, Dr. Levine concluded that members of a group take responsibility for the safety of others they see as belonging to the same group — and that the sense of group membership can be broadened.
	www.safety-council.org /info/community/bystander.html (759 words)

	Radiation bystander effects
		Los Alamos National Laboratory biologist Bruce Lehnert's study of the effects of extracellular mediators, including proteins, from irradiated human cells on non-irradiated cells has confirmed the existence of the so-called "bystander effect," which essentially refers to radiation- induced effects in unirradiated cells.
		Results from recent experiments show that at least some cancer-associated effects of ionizing radiation, including the induction of genetic mutations, can occur in cells that have not been directly exposed to radiation.These results have profound implications for assessing cancer risk and other collateral effects of environmental, diagnostic or therapeutic exposure to ionizing radiation.
		A second important bystander effect is that the growth of cells is enhanced, and cells showing this response fail to stop growing when subsequently exposed to radiation.
	www.eurekalert.org /features/doe/2001-07/danl-rbe060702.php (717 words)

	Bystander Effects of Cancer Cell Lines Transduced with the Multisubstrate Deoxyribonucleoside Kinase of Drosophila ...
		Bi WL, Parysek LM, Warnick R and Stambrook PJ (1993) In vitro evidence that metabolic cooperation is responsible for the bystander effect observed with HSV tk retroviral gene therapy.
		Degreve B, De Clercq E and Balzarini J (1999) Bystander effect of purine nucleoside analogues in HSV-1 tk suicide gene therapy is superior to that of pyrimidine nucleoside analogues.
		Touraine RL, Vahanian N, Ramsey WJ and Blaese RM (1998) Enhancement of the herpes simplex virus thymidine kinase/ganciclovir bystander effect and its antitumor efficacy in vivo by pharmacologic manipulation of gap junctions.
	molpharm.aspetjournals.org /cgi/content/full/60/2/262 (3302 words)

	BioMed Central \| Full text \| Dexamethasone inhibits the HSV-tk/ ganciclovir bystander effect in malignant glioma cells
		In most tumor types, the bystander effect relies on the transfer of phosphorylated ganciclovir molecules between cells via their gap junctions [6,7], although other mechanisms have been described in some models [8-11].
		Dexamethasone is indeed commonly used for the symptomatic treatment of brain tumor patients, and the bystander effect is considered a major contributor to the efficacy of type of suicide gene therapy [20,21].
		The in vitro bystander effect in glioma cells depends on the transfer of phosphorylated ganciclovir molecules trough gap junctions [23,7].
	www.biomedcentral.com /1471-2407/5/32 (4507 words)

	Bystander effect-mediated gene therapy of gliomas using genetically engineered neural stem cells.
		Bystander effect-mediated gene therapy of gliomas using genetically engineered neural stem cells.
		We first evaluated the "bystander effect" between NSCs transduced with the herpes simplex virus-thymidine kinase (HSVtk) gene (NSCtk) and C6 rat glioma cells under both in vitro and in vivo conditions.
		A potent bystander effect was observed in co-culture experiments of NSCtk and C6 cells.
	braintumors.researchtoday.net /archive/2/6/666.htm (311 words)

	CalendarHome.com - - Calendar Encyclopedia (Site not responding. Last check: )
		In an unrelated use, the term bystander effect is also used in radiobiology to describe the effects of radiation on cells that are adjacent to those directly affected by radiation.
		The bystander effect (also known as bystander apathy or bystander intervention) is a psychological phenomenon in which someone is less likely to intervene in an emergency situation when others are present than when he or she is alone.
		To counter the bystander effect when you are the victim, a studied recommendation is to pick a specific person in the crowd to appeal to for help rather than appealing to the larger group generally.
	encyclopedia.calendarhome.com /cgi-bin/encyclopedia.pl?p=Bystander_effect (701 words)

	Bystander effect and adaptive response in C3H 10T½ cells - Mitchell et al / International Journal of Radiation Biology ...
		The bystander effect is defined as the observation of a biological response in cells which have not been directly traversed by ionizing radiation but which results from signals initiating in cells in which energy has been deposited.
		Although the effect of such bystander responses on the low-dose cancer risk is not fully understood (4), they are thought to represent a balance between protective mechanisms such as apoptosis and differentiation (5) and potentially harmful mechanisms, in which DNA damage and potential genomic instability are mediated through bystander signals (3, 6).
		However, the amount of cell killing, and by implication the magnitude of the bystander effect, was significantly greater in the high-density cultures, with an approximately 2.5-fold increase in the amount of cell killing at the highest dose tested.
	www.mindfully.org /Nucs/2004/Bystander-Effect-Radiation1jul04.htm (3617 words)

	Contact Us (Site not responding. Last check: )
		This bystander effects is a phenomena which is brought about by low-dose radiation that is very lethal upon exposure; is very harmful to mammalian cells because it causes cellular death, that it causes different abnormality in the cellular function, morphology, physiology and genetics.
		The radiation-induced bystander effect is the phenomenon whereby cellular effects such as cellular death and killing, sister chromatid exchanges, chromosomal aberrations, apoptosis, micronucleation, transformation, genetic or cellular mutations, differentiation and changes of gene expression are expressed in unirradiated neighboring cells near to an irradiated cell or cells.
		The bystander effect describes the non-irradiated cells that are neighbors of irradiated cells often show altered mutation and cell killing rates in contrast to distant non-irradiated or sham irradiated cells, and also in contrast to irradiated cells (Prise et al, 2003).
	members.tripod.com /jjc_bio04/researches.htm (2232 words)

	Do Low Dose-Rate Bystander Effects Influence Domestic Radon Risks?
		It attributes bystander effects to a small subpopulation of hypersensitive cells, with the bystander contribution dominating the direct contribution at very low acute doses but saturating as the dose increases.
		Inverse dose-rate effects are attributed to replenishment of the hypersensitive subpopulation during prolonged irradiation.
		In conclusion, bystander effects represent a plausible quantitative and mechanistic explanation of inverse dose-rate effects by high-LET radiation, resulting in dose-response relations which are non linear and which feature a complex interplay between the effects of dose and exposure time.
	www.raraf.org /radon_risks.htm (1232 words)

	Radon risks and low dose-rate bystander effects
		It attributes bystander effects to a small subpopulation of hypersensitive cells, with the bystander contribution dominating the direct contribution at very low acute doses but saturating as the dose increases.
		Inverse dose-rate effects are attributed to replenishment of the hypersensitive subpopulation during prolonged irradiation.
		We shall argue that when bystander effects are taken into account, a similar situation should hold, provided the concept of "one target" is appropriately enlarged to include all the bystander cells that can be signaled from a hit cell.
	math.berkeley.edu /~sachs/sachsresearch/papers0102/radon2.html (1900 words)

	Bystander effects in cell induced by photodynamic treatment, UVA radiation and inhibitors of ATP synthesis ...
		It is shown that a statistically significant bystander effect is involved in PDTmediated inactivation of cells in confluent layers using a number of photosensitizers, as well as in treatment with metabolic inhibitors and ultraviolet radiation in the wavelength region of 320-400 nm (UVA).
		Therefore, a bystander effect induced by UVA radiation indicates that the bystander effect in PDT is not just an artifact produced by differences among individual cells in their uptake of photosensitizers.
		Different mechanisms may be involved in the bystander effects observed with different kinds of cell inactivation, but bystander effects seem to be involved in many kinds of cell death.
	www.findarticles.com /p/articles/mi_qa3931/is_200104/ai_n8930951 (1032 words)

	HST Forum 2004: Rong Wang
		Bystander effects, mostly in normal cells, have been reported where irradiated cells release a factor that can produce damage or death in neighboring cells.
		In order to explore the bystander effect in tumor cells, especially its implication in radioimmunotherapy, an apparatus for alpha particle irradiation of cells growing as a monolayer on a thin mylar membrane directly above an americium-241 alpha particle source has been constructed and calibrated.
		A novel co-culture system was designed for bystander effect detection: cells growing on the bottom mylar membrane are directly exposed to alpha particles; cells co-cultivated on an inserts, positioned 3 mm above the bottom cell layer and out of the range of the alpha particles, serve as the non-targeted bystander cells.
	hst.mit.edu /forum2004/Abstracts/Wang.html (472 words)

	Inhibition of Angiogenesis and Induction of Apoptosis Are Involved in E1A-mediated Bystander Effect and Tumor ...
		Inhibition of Angiogenesis and Induction of Apoptosis Are Involved in E1A-mediated Bystander Effect and Tumor Suppression -- Shao et al.
		Inhibition of Angiogenesis and Induction of Apoptosis Are Involved in E1A-mediated Bystander Effect and Tumor Suppression
		effect and the mechanisms that may be associated with it.
	cancerres.aacrjournals.org /cgi/content/abstract/60/12/3123 (712 words)

	vgn-ext-hidden_Abstract (Site not responding. Last check: )
		The application of suicide gene therapy to refractory malignancies relies on the demonstrated bystander effect in vivo and in vitro.
		These cytokines may mediate the hemorrhagic tumor necrosis that is seen in vivo, in models of the bystander effect.
		Effects of AMD3100 on transmigration and survival of acute myelogenous leukemia cells.
	www.asco.org /portal/site/ASCO/menuitem.34d60f5624ba07fd506fe310ee37a01d/?vgnextoid=76f8201eb61a7010VgnVCM100000ed730ad1RCRD&vmview=abst_detail_view&confID=29&abstractID=9671 (724 words)

	Bystander effect induced by counted high-LET particles in confluent human fibroblasts: a mechanistic study -- SHAO et ...
		Bystander effect induced by counted high-LET particles in confluent human fibroblasts: a mechanistic study -- SHAO et al.
		in the induction of the bystander response in a confluent culture.
		Mothersill, C., Seymour, C. (1998) Cell-cell contact during gamma irradiation is not required to induce a bystander effect in normal human keratinocytes: evidence for release during irradiation of a signal controlling survival into the medium.
	www.fasebj.org /cgi/content/full/17/11/1422 (3810 words)

	Guilt and the bystander effect in the Computer lab
		The bystander effect, coined by psychologists is a theory that says the more people around, the less likely someone will act.
		An example study for the bystander effect is the Latane and Darley study performed in 1968.
		Our conclusion is that because of the bystander effect and the guilt factor, people would not get off the computers when other’s around them were wasting time as well.
	cas.bellarmine.edu /tietjen/images/guilt_and_the_bystander_effect_i.htm (840 words)

	Bystander Effects and Alpha-Particle Induced Cancer
		The 'bystander effect' is a term coined to describe a range of biological phenomena whereby mammalian cells irradiated in culture produce damage-response signals which are communicated to their unirradiated neighbours
		Thus, the bystander effect appeared to be generating new mutations within the 90% of cells that had not received alpha particles.
		Similar rapidly expressing bystander effects were demonstrated for one form of chromosomal damage and elegant methods were used to show that the mutagenic effect in question was dependent upon the activity of inter-cellular junctions of communication.
	www.hpa.org.uk /hpa/news/nrpb_archive/response_statements/2001/response_statement_7_01.htm (721 words)

	2001 Annual Report
		In addition, the bystander effect for HPRT mutation in Hx cells was determined by irradiating 10% of the cell nuclei with 20 alpha particles.
		There is a decrease in the bystander effect for mutation when neighbor cells are traversed by one particle and a somewhat smaller decrease for traversal by 20 particles.
		Damage induction in irradiated and bystander cells is being studied by Gloria Jenkins and Charles Geard of the CRR (Exp. 103).
	cpmcnet.columbia.edu /dept/radoncology/raraf/ar2001.htm (4000 words)

	Radiation risks: cytogenetic and molecular tests (DOE grant)
		Bystander effects are considered important to radiation risk, especially for low doses of high LET radiation, where few cells are hit directly.
		The objective of the proposed research is to develop quantitative estimates of radiation bystander effects applicable to low dose radiation risk estimation.
		A key parameter for analyses of bystander effects, especially for risk estimation, is the average number, N, of cells close enough to a cell sending out bystander signal that they can be strongly influenced by the signal.
	math.berkeley.edu /~sachs/sachsresearch/grants/doe.html (1352 words)

	Bystander Effect of Introgen's INGN 241 Increases Cancer-Killing Activity in Breast Cancer Cells (Site not responding. Last check: )
		This bystander effect occurs when the therapeutic protein binds to certain receptors on nearby cancer cells.
		"The observed bystander effect reported today is significant because it indicates that the number of cancer cells that can be killed by INGN 241 is larger than the number of cells that take up this novel investigational cancer therapy.
		"The bystander effect observed with secreted MDA-7 protein may be important in the treatment of cancer because it may increase our ability to eliminate as many cancer cells as possible, even cells that have not been directly treated with INGN 241.
	www.pslgroup.com /dg/252ADA.htm (626 words)

	BBC - h2g2 - Bystander Effect
		The Bystander Effect is a psychological phenomenon that occurs when an emergency situation is presented to a group of people.
		The most famous example of this and what kick-started researchers to study the Bystander Effect, was an event during 1964.
		Kitty Genovese was stabbed to death in front of an apartment complex, with 38 people who lived there watching or listening.
	www.bbc.co.uk /dna/h2g2/A585362 (486 words)

	Latane and Darley: Bystander Apathy
		The bystander can only gain with pride and a hero's status -- but he risks being a failure, getting sued, or even attacked or wounded himself.
		One with the subject and a real friend as bystanders, and one where six real subjects had prior contact and a brief "encounter" with the percieved victim.
		Sex of bystander and medical competence had no effect on the results.
	faculty.babson.edu /krollag/org_site/soc_psych/latane_bystand.html (1259 words)

	The Bystander Effect: Why Don't We Stop to Help? - Associated Content
		The bystander effect simply put, states that the more bystanders present, the less likely it is for someone to help.
		Many of the classic experiments that demonstrated the bystander effects were conducted in the 1960s and 70s.
		This famous case of the bystander effect shined light on this seemingly common human condition.
	www.associatedcontent.com /article/207074/the_bystander_effect_why_dont_we_stop.html (659 words)

	THE EFFECTS OF LOCUS OF CONTROL ON HELPING BEHAVIOR AND THE BYSTANDER INTERVENTION EFFECT
		It is believed that the bystander effect is caused by at least two processes.
		The second is that a bystander is less likely to help unless he or she feels a personal responsibility to do so.
		Those with an external locus of control may pass responsibility to someone else, or may believe that it is the victim's fault for being in that situation, and he or she deserves it.
	clearinghouse.missouriwestern.edu /manuscripts/3.asp?logon=&code= (1905 words)

	Re: LNT and Bystander Effect (Site not responding. Last check: )
		Bystander cells may respond to damage of the target cell.
		The model postulates that the oncogenic bystander response is a binary "all or nothing" phenomenon in a small sensitive subpopulation of cells, and that cells from this sensitive subpopulation are also very sensitive to direct hits from alpha particles, generally resulting in a directly hit sensitive cell being inactivated.
		At still lower doses, bystander effects may dominate the overall response, possibly leading to an underestimation of low-dose risks extrapolated from intermediate doses, where direct effects dominate.
	www.vanderbilt.edu /radsafe/0103/msg00112.html (625 words)

	Students OnCourse
		This student chose to write a poem as her learning option, illustrating aspects of the Bystander Effect, as well as explaining correlations between the events in the poem and attributes of the psychological phenomenon.
		Through social experiments, they determined that in order for a bystander to provide help in an emergency situation, three conditions must be met: the bystander must notice the emergency, the bystander must interpret the situation as being an emergency, and the bystander must feel responsible for helping.
		Our second bystander notices someone lying immobile on a sidewalk, but “angry looks” usually are not directed at a person in need of assistance, and he therefore concludes that the person must not need help.
	www.coconino.edu /studentsoncourse/SOCStandBy.html (719 words)

	M (Site not responding. Last check: )
		Recent advances in radiobiology have established that in cell populations exposed to ionizing radiation, the biological effects occur in a much larger proportion of cells than are estimated to be traversed by radiation.
		Direct evidence of the bystander effect was provided in studies where the transfer of medium from irradiated cells was shown to reduce the plating efficiency of unirradiated bystander cells.
		We are examining the global gene expression alterations in bystander cells with DNA microarray technology to gain insight into the molecular pathways responsible for the bystander effect.
	www.uvm.edu /~cnhs/BMT/Faculty/ahmad.html (704 words)

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