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Carbohydrate vaccine elicits unexpectedly strong response In the first study to quantify levels of anti body elicited in patients immunized with a carbohydrate-based anticancer vaccine, researchers have found that one such vaccine currently in clinical trials as a prostate-cancer treatment produces an unexpectedly strong response. The vac cine is based on globo H, a carbohydrate antigen overexpressed on surfaces of hu man prostatic cancer cells. Chemistry professor Samuel J. Danishefsky and co workers at Memorial Sloan-Kettering Cancer Center, New York City, synthe sized the antigen and conjugated it to a protein to make it immunogenic. The re sulting conjugate vaccine recently was found to be well tolerated by prostate can cer patients in Phase I safety trials. Danishefsky's group, in collaboration with other Sloan-Kettering teams, has now at tached the antigen to an affinity matrix to isolate and identify antibodies elicited by the vaccine in human patients [Proc. Natl. Acad. Sci. USA, 9 7 , 2719 (2000)]. The level of antibody generated was con siderably higher than the amount of anti body produced by an antibacterial poly saccharide vaccine. The latter would be expected to be more immunogenic, be cause it is a foreign antigen, whereas globo H is a human antigen. The technique for isolating vaccine-elicited antibodies could facilitate their diagnostic and therapeutic use and studies of the mechanisms by which antibodies target cancer cells. Phase II clinical trials of the globo H vac cine are expected to commence soon.^
Oceans absorb more C0 2 than land
0.8 billion tons was absorbed by the land, and 2.0 ± 0.6 billion tons was absorbed by the oceans. This is in sharp contrast to the 1977-90 period, when the land ap peared to be neither a source nor a sink for C0 2 . However, Battle and Bender found that the uptake of C0 2 by the land from 1991 to 1997 was highly variable from year to year and "must be driven by climate." They used two methods of cal culating the C0 2 flux for the land bio sphere. One is based on measurements of the rate of change of the 0 2 /N 2 ratio in air. The second approach involves mea suring the change in the isotopic compo sition of atmospheric C 0 2 . ^
Versatile catalyst for the Strecker reaction A general catalyst for the asymmetric Strecker reaction has been identified from a combinatorial library. The Streck
er reaction is T/^M Ο widely used to prepare deriva tives of α-amino acids. Enantioselective variants of the re action have been the goal of much re search in asymmetric synthesis, includ ing that in the lab of Harvard University chemistry professor Eric N. Jacobsen. With former postdoc Matthew S. Sigman (now an assistant professor of chemistry at the University of Utah) and graduate student Petr Vachal, Jacobsen has dem onstrated that the compound shown (X = O; R = C6H5) can catalyze the asymmetric Strecker reaction in solution for a wide range of aromatic and aliphatic imines [Angew. Chem. Int. Ed, 39,1279 (2000)]. For many substrates, enantiomeric ex cesses exceed 90%. An analog bound to a resin (X = S; R = polystyrene) gives 2 to 4% lower enantiomeric excesses but can be recycled up to 10 times without loss of activity or enantioselectivity.^
Between 1991 and 1997, the world's oceans absorbed more carbon dioxide than the land biosphere did, reports a re search team led by Mark 0. Battle of the department of physics at Bowdoin Col lege, Brunswick, Maine, and Michael L. Bender of the department of geoscience Viral coating probed at Princeton University [Science, 287, by mass spectrometry 2467 (2000)]. Burning of fossil fuels add ed roughly 6.2 billion tons of C0 2 (mea A mass spectrum has been obtained for sured as carbon) to the atmosphere each the largest noncovalently assembled year from 1991 to 1997. Of this, 2.8 billion particle to date, reports Carol V. Robin tons remained in the atmosphere, 1.4 ± son, professor of chemistry at the Uni 30
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versity of Oxford \J. Am. Chem. Soc, 1 2 2 , 3550 (2000)]. Robinson, along with doctoral student Mark A. Tito and colleagues at Sweden's Uppsala Univer sity, examined the protein shell—or capsid—of the bacteriophage MS2, a vi rus that infects bacterial cells. The in tact capsid consists of 180 copies of the coat protein. The researchers used an electrospray (ES) technique to create a fine spray of charged capsid ions, which were then cooled through collisions with molecules of nitrogen. That damp ens the explosive force of the ES pro cess, preventing the capsid ions from breaking apart as they speed to the mass analyzer in a time-of-flight (TOF) mass spectrometer. The authors also ran their ES-TOF analysis without the cooling step to obtain information about the arrangement of the capsid's protein subunits. Their results suggest that the protein coat is constructed from hexameric building blocks. They note that these results are consistent with the tri mer of dimers previously observed in the X-ray crystal structure.^
Multilayer polymer mirrors outshine others Mirrors have traditionally been made of inorganic materials like metal and glass. But new mirrors composed of thin, alter nating layers of two common polymers such as polyester have been found to out shine all the others. Although the com mon bathroom mirror reflects light from all directions, it absorbs some of the light instead of reflecting it. Conventional di electric mirrors, on the other hand, ab sorb less incident light, but they have trouble reflecting light coming in at sharp angles. Unlike these older mirrors, the new polymer-based mirrors can reflect visible light from all angles with great ef ficiency. Furthermore, the polymer mir rors are thin, flexible, inexpensive, versa tile, and easy to make in large volume. The first scientific report on these mir rors was published last week in Science [ 2 8 7 , 2451 (2000)] by Andrew J. Ouderkirk and colleagues at 3M's tech nology center in St. Paul, Minn. 3M has already begun to commercialize several applications of the mirrors, such as a way of using them to improve the brightness and readability of screens on handheld computers and laptops. The polymer mir rors also are extremely effective at "pip ing" visible light over great distances without affecting its color or intensity.^
