ScienceDaily (Jan. 5, 2012) — A national clinical trial testing the efficacy of a novel brain tumor vaccine has begun at Wake Forest Baptist Medical Center, the only facility in the Southeast to participate. The vaccine will be tested in patients with newly diagnosed glioblastoma multiforme (GBM), the most aggressive and highest grade malignant glioma. Wake Forest Baptist will treat a minimum of 25 patients in this randomized, placebo-controlled phase II clinical trial of ICT-107. A total of 20 sites across the country are participating in the trial to test the safety and efficacy of this novel cancer vaccine.
All patients enrolled in the study will receive the current standard treatment for GBM, which includes surgery followed by radiation and chemotherapy. Two thirds of the participants will then also get the experimental vaccine treatment, which will be administered in the post radiation phase of treatment, while the others will get a "dummy," or placebo vaccine in addition to standard therapy.
"This vaccine is for newly-diagnosed patients," said Glenn Lesser, M.D., a professor of internal medicine, hematology-oncology, at Wake Forest Baptist and principal investigator for the study. "Scientifically, it's a very well designed study and we are excited to participate in this clinical trial. We've been asked to participate based on our reputation as an outstanding brain tumor center and the expertise our center has with bringing novel therapies and novel therapeutics to patients."
The approach with this particular vaccine is unique, Lesser added, because it is targeting the antigens or proteins that are present on glioma stem cells, whereas other treatment approaches mostly target differentiated tumor cells.
"The antigens used in this vaccine target the tumor stem cells -- the handful of cells that keep the tumor alive and dividing. Most of the cells we kill with standard treatment are likely not the ones driving the tumor growth. If the stem cells aren't targeted, they keep generating more tumors."
According to the biotechnology company that is conducting the trial, the Phase I clinical study of ICT-107 in GBM involved 16 newly-diagnosed patients who received the vaccine in addition to standard therapy -- surgery, radiation and chemotherapy. Those patients demonstrated a one-year overall survival of 100 percent and a two-year survival of 80 percent. Although only a small number of patients were treated, these results compare favorably with historical 61percent one-year and 26 percent two-year survival with standard care alone.
Vaccines for brain tumors are new and experimental, said Lesser, but are gaining more attention in the glioma world. "Vaccines are a way to harness the body's own defenses -- which are usually used to ward off or control infections like the flu -- to fight cancer cells instead," Lesser explained. "It is a way of presenting antigens or proteins normally found on the surface of the cancer cells to the immune system so that immune cells can seek out and kill those cancer cells anywhere in the body. This is not unlike giving a piece of clothing to a bloodhound and then letting it loose to find a missing person."
Wake Forest Baptist is also involved in another brain tumor vaccine trial for patients with low-grade or slower growing gliomas. Among the targets of both of these vaccines is a new protein found on the surface of glioma cells discovered by Waldemar Debinski, M.D., Ph.D, director of the Wake Forest Baptist Brain Tumor Center of Excellence.
"Early studies of vaccines for patients with brain tumors are showing promising results," Lesser said. "We want to help definitively determine how good these novel therapies really are for patients."
Saturday, January 7, 2012
What Determines the Capacity of Short-Term Memory?
ScienceDaily (Dec. 15, 2011) — Short-term memory plays a crucial role in how our consciousness operates. Several years ago a hypothesis has been formulated, according to which capacity of short-term memory depends in a special way on two cycles of brain electric activity. Scientists from the Nencki Institute of Experimental Biology of the Polish Academy of Sciences in Warsaw have now demonstrated this experimentally for the first time.
A human being can consciously process from five to nine pieces of information simultaneously. During processing these pieces of information remain in the short-term memory. In 1995 researchers from Brandeis University in Waltham suggested that the capacity of short-term memory could depend on two bands of brain's electric activity: theta and gamma waves. However, only now, through carefully designed experiments conducted at the Nencki Experimental Biology Institute of the Polish Academy of Sciences (Nencki Institute) in Warsaw, it was possible to unambiguously prove that such a relationship really exists.
For an electroencephalography exam (EEG) several electrodes are placed on patient's head. The recorded brain electric signals contain waves of different frequencies, among other theta waves with the frequency of 4-7 Hz and gamma waves with the frequency of 25-50 Hz. It has been known for some time that these waves are used for retaining information in the brain. It was observed for example that the amplitudes of theta and gamma waves increased when people were forced to store more information in short-term memory.
"The hypothesis formulated by Lisman and Idiart in 1995 assumes that we are able to memorise as many 'bites' of information, as there are gamma cycles for one theta cycle. Research to date provided only indirect support for this hypothesis," say psychologist Jan Kamiński, PhD student from the Nencki Institute and main author of experiments conducted by the team of Prof. Andrzej Wróbel in cooperation with Dr. Aneta Brzezicka from the Warsaw School of Social Sciences and Humanities.
A 'bite' of information refers to its portion in memory. A 'bite' may be a number, letter, idea, situation, picture or smell. "Designing experiments on the capacity of memory one needs to be very careful not to make it too easy for the subject to group many 'bites' into one," stresses Kamiński and as an example gives the following sequence of letters: 2, 0, 1, 1. "Such four 'bites' of information are easy to group into the number corresponding to current year. Instead of four bites of information we are left with just one."
Interpreting the length of theta and gamma waves from EEG recording is not easy either. These waves are not directly visible in the EEG signal. Kamiński proposed a new method of determining them. Researchers recorded brain's electric activity in seventeen volunteers resting with closed eyes for five minutes. Next they filtered the signals and analysed not the cycles themselves but their correlations. Only based on discovered correlations the ratio of the length of theta wave to gamma wave was determined and the likely capacity of verbal short-term memory was determined.
Following the EEG recording, the volunteers, were subjected to classic short-term memory capacity test. It consisted of repeated display of longer and longer sequences of numbers. Each number was presented for one second. Then volunteers had to reconstruct the sequence from memory. At first the sequence consisted of three numbers but at the end of the exam of as many as nine. "We have observed that the longer the theta cycles, the more information 'bites' the subject was able to remember; the longer the gamma cycle, the less the subject remembered. Next we determined the correlation between the results of the tests and estimates from the EEG measurements. Just as expected the correlation turned out to be very high and it confirmed the hypothesis of Lisman and Idiart," says Kamiński.
Capacity of short-term memory impacts the effects of reasoning -- the greater the capacity, the better the effects. Currently researchers conduct studies on developing the most effective ways of training short-term memory.
A human being can consciously process from five to nine pieces of information simultaneously. During processing these pieces of information remain in the short-term memory. In 1995 researchers from Brandeis University in Waltham suggested that the capacity of short-term memory could depend on two bands of brain's electric activity: theta and gamma waves. However, only now, through carefully designed experiments conducted at the Nencki Experimental Biology Institute of the Polish Academy of Sciences (Nencki Institute) in Warsaw, it was possible to unambiguously prove that such a relationship really exists.
For an electroencephalography exam (EEG) several electrodes are placed on patient's head. The recorded brain electric signals contain waves of different frequencies, among other theta waves with the frequency of 4-7 Hz and gamma waves with the frequency of 25-50 Hz. It has been known for some time that these waves are used for retaining information in the brain. It was observed for example that the amplitudes of theta and gamma waves increased when people were forced to store more information in short-term memory.
"The hypothesis formulated by Lisman and Idiart in 1995 assumes that we are able to memorise as many 'bites' of information, as there are gamma cycles for one theta cycle. Research to date provided only indirect support for this hypothesis," say psychologist Jan Kamiński, PhD student from the Nencki Institute and main author of experiments conducted by the team of Prof. Andrzej Wróbel in cooperation with Dr. Aneta Brzezicka from the Warsaw School of Social Sciences and Humanities.
A 'bite' of information refers to its portion in memory. A 'bite' may be a number, letter, idea, situation, picture or smell. "Designing experiments on the capacity of memory one needs to be very careful not to make it too easy for the subject to group many 'bites' into one," stresses Kamiński and as an example gives the following sequence of letters: 2, 0, 1, 1. "Such four 'bites' of information are easy to group into the number corresponding to current year. Instead of four bites of information we are left with just one."
Interpreting the length of theta and gamma waves from EEG recording is not easy either. These waves are not directly visible in the EEG signal. Kamiński proposed a new method of determining them. Researchers recorded brain's electric activity in seventeen volunteers resting with closed eyes for five minutes. Next they filtered the signals and analysed not the cycles themselves but their correlations. Only based on discovered correlations the ratio of the length of theta wave to gamma wave was determined and the likely capacity of verbal short-term memory was determined.
Following the EEG recording, the volunteers, were subjected to classic short-term memory capacity test. It consisted of repeated display of longer and longer sequences of numbers. Each number was presented for one second. Then volunteers had to reconstruct the sequence from memory. At first the sequence consisted of three numbers but at the end of the exam of as many as nine. "We have observed that the longer the theta cycles, the more information 'bites' the subject was able to remember; the longer the gamma cycle, the less the subject remembered. Next we determined the correlation between the results of the tests and estimates from the EEG measurements. Just as expected the correlation turned out to be very high and it confirmed the hypothesis of Lisman and Idiart," says Kamiński.
Capacity of short-term memory impacts the effects of reasoning -- the greater the capacity, the better the effects. Currently researchers conduct studies on developing the most effective ways of training short-term memory.
Subscribe to:
Posts (Atom)
