239 research outputs found
The pharmacologic basis of high dose chemotherapy with haematopoietic stem cell support for solid tumours
The theoretical basis of high dose chemotherapy with haematopoietic stem cell support (HDT) for solid tumours is the presumption of a linear, steep dose-response relationship for chemotherapy conditioning agents. We review preclinical pharmacologic studies evaluating steep dose-response relationships for different chemotherapeutic agents, identified through a MED-LINE and CANCER-LIT search of the English medical literature from January 1966 to December 1999. Only BCNU, melphalan, nitrogen mustard, and the combination of thiotepa and cyclophosphamide demonstrated steep dose-response relationships over a wide dose-range. The pharmacologic evidence for the use of other antineoplastic agents for HDT in solid tumours is non-existent. More preclinical studies are needed for a rational development of this therapeutic approach for solid tumours. © 2001 Cancer Research Campaign http://www.bjcancer.co
Apolipoprotein E Allelic Frequency Altered in Women with Early-onset Breast Cancer
Among women, the most prevalent type of cancer is breast cancer, affecting 1 out of every 8 women in the United States; in Puerto Rico, 70 out of every 100,000 will develop some type of breast cancer. Therefore, a better understand of the potential risk factors for breast cancer could lead to the development of early detection tools. A gene that has been proposed as a risk factor in several populations around the world is Apolipoprotein E (apoE). ApoE functions as a mechanism of transport for lipoproteins and cholesterol throughout the body, with 3 main isoforms present in humans (apoE2, apoE3, and apoE4). Whether or not apoE4 is a risk factor for breast cancer remains controversial. Previous studies have either included test subjects of all ages (20–80) or have focused on late-onset (after age 50) breast cancer; none has concentrated specifically on early-onset (aged 50 and younger) breast cancer. The objectives of this study was to examine (in a Puerto Rican population) the differences in the relative frequency of occurrence of apoE4 in non-breast cancer versus breast cancer patients and to examine, as well, the potential differences of same in early- versus late-onset patients. We found an increased frequency of apoE4 (odds ratio 2.15) only in early-onset breast cancer survivors, which is similar to the findings of those studies that combined or adjusted for age as well as for an association between apoE4 and decreased tumor size. ApoE is also a potential risk factor for long-term cognitive effects after chemotherapy and affects response to hormone replacement. Our data supports the theory that knowing the apoE genotype of women who are at risk of developing breast cancer may be beneficial, as such knowledge would aid in the prediction of tumor size and the development of treatment regimens
The Taiwanese-American Occultation Survey: The Multi-Telescope Robotic Observatory
The Taiwanese-American Occultation Survey (TAOS) operates four fully
automatic telescopes to search for occultations of stars by Kuiper Belt
Objects. It is a versatile facility that is also useful for the study of
initial optical GRB afterglows. This paper provides a detailed description of
the TAOS multi-telescope system, control software, and high-speed imaging.Comment: 11 pages, 11 figure
The TAOS Project Stellar Variability I. Detection of Low-Amplitude delta Scuti Stars
We analyzed data accumulated during 2005 and 2006 by the Taiwan-American
Occultation Survey (TAOS) in order to detect short-period variable stars
(periods of <~ 1 hour) such as delta Scuti. TAOS is designed for the detection
of stellar occultation by small-size Kuiper Belt Objects (KBOs) and is
operating four 50cm telescopes at an effective cadence of 5Hz. The four
telescopes simultaneously monitor the same patch of the sky in order to reduce
false positives. To detect short-period variables, we used the Fast Fourier
Transform algorithm (FFT) inasmuch as the data points in TAOS light-curves are
evenly spaced. Using FFT, we found 41 short-period variables with amplitudes
smaller than a few hundredths of a magnitude and periods of about an hour,
which suggest that they are low-amplitude delta Scuti stars (LADS). The
light-curves of TAOS delta Scuti stars are accessible online at the Time Series
Center website (http://timemachine.iic.harvard.edu)Comment: Accepted for publication in A
Optical Properties of Deep Ice at the South Pole - Absorption
We discuss recent measurements of the wavelength-dependent absorption
coefficients in deep South Pole ice. The method uses transit time distributions
of pulses from a variable-frequency laser sent between emitters and receivers
embedded in the ice. At depths of 800 to 1000 m scattering is dominated by
residual air bubbles, whereas absorption occurs both in ice itself and in
insoluble impurities. The absorption coefficient increases approximately
exponentially with wavelength in the measured interval 410 to 610 nm. At the
shortest wavelength our value is about a factor 20 below previous values
obtained for laboratory ice and lake ice; with increasing wavelength the
discrepancy with previous measurements decreases. At around 415 to 500 nm the
experimental uncertainties are small enough for us to resolve an extrinsic
contribution to absorption in ice: submicron dust particles contribute by an
amount that increases with depth and corresponds well with the expected
increase seen near the Last Glacial Maximum in Vostok and Dome C ice cores. The
laser pulse method allows remote mapping of gross structure in dust
concentration as a function of depth in glacial ice.Comment: 26 pages, LaTex, Accepted for publication in Applied Optics. 9
figures, not included, available on request from [email protected]
A Close Binary Star Resolved from Occultation by 87 Sylvia
The star BD+29 1748 was resolved to be a close binary from its occultation by
the asteroid 87 Sylvia on 2006 December 18 UT. Four telescopes were used to
observe this event at two sites separated by some 80 km apart. Two flux drops
were observed at one site, whereas only one flux drop was detected at the
other. From the long-term variation of Sylvia, we inferred the probable shape
of the shadow during the occultation, and this in turn constrains the binary
parameters: the two components of BD+29 1748 have a projected separation of
0.097" to 0.110" on the sky with a position angle 104 deg to 107 deg. The
asteroid was clearly resolved with a size scale ranging from 130 to 290 km, as
projected onto the occultation direction. No occultation was detected for
either of the two known moonlets of 87 Sylvia.Comment: 12 pages, 4 figures, 2 tables; submitted to the PAS
First Results From The Taiwanese-American Occultation Survey (TAOS)
Results from the first two years of data from the Taiwanese-American
Occultation Survey (TAOS) are presented. Stars have been monitored
photometrically at 4 Hz or 5 Hz to search for occultations by small (~3 km)
Kuiper Belt Objects (KBOs). No statistically significant events were found,
allowing us to present an upper bound to the size distribution of KBOs with
diameters 0.5 km < D < 28 km.Comment: 5 pages, 5 figure, accepted in Ap
Discovery of the Optical Transient of the Gamma Ray Burst 990308
The optical transient of the faint Gamma Ray Burst 990308 was detected by the
QUEST camera on the Venezuelan 1-m Schmidt telescope starting 3.28 hours after
the burst. Our photometry gives , , , and for times ranging from 3.28 to 3.47
hours after the burst. The colors correspond to a spectral slope of close to
. Within the standard synchrotron fireball model,
this requires that the external medium be less dense than , the
electrons contain of the shock energy, and the magnetic field energy
must be less than 24% of the energy in the electrons for normal interstellar or
circumstellar densities. We also report upper limits of at 132 s
(with LOTIS), from 132-1029s (with LOTIS), at 28.2 min
(with Super-LOTIS), and a 8.5 GHz flux of at 110 days (with the
Very Large Array). WIYN 3.5-m and Keck 10-m telescopes reveal this location to
be empty of any host galaxy to and . The lack of a host
galaxy likely implies that it is either substantially subluminous or more
distant than a red shift of .Comment: ApJ Lett submitted, 5 pages, 2 figures, no space for 12 coauthor
The AMANDA Neutrino Telescope and the Indirect Search for Dark Matter
With an effective telescope area of order 10^4 m^2, a threshold of ~50 GeV
and a pointing accuracy of 2.5 degrees, the AMANDA detector represents the
first of a new generation of high energy neutrino telescopes, reaching a scale
envisaged over 25 years ago. We describe its performance, focussing on the
capability to detect halo dark matter particles via their annihilation into
neutrinos.Comment: Latex2.09, 16 pages, uses epsf.sty to place 15 postscript figures.
Talk presented at the 3rd International Symposium on Sources and Detection of
Dark Matter in the Universe (DM98), Santa Monica, California, Feb. 199
Early optical brightening in GRB 071010B
We report the detection of early (60-230 s) optical emission of the gamma-ray burst afterglow of GRB 071010B. No significant correlation with the prompt γ-ray emission was found. Our high time resolution data combining with other measurements within 2 days after the burst indicate that GRB 071010B is composed of a weak early brightening (α ~ 0.6), probably caused by the peak frequency passing through the optical wavelengths, followed by a decay (α ~ − 0.51), attributed to continuous energy injection by patchy jets
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