108 Nature Vol. 280 12 July 1979 example, the J/tp at 3.1 GeV and the jet structure survives the final 'colour­ beneficial in shock cases. High molecular upsilon at 9.4 GeV. In these bound states washing' that creates only colourless weight dextran has anticoagulant activity the heavy quark-antiquark pair can decay hadrons out of the quark and the and it can be used for this purpose after hadronically only by annihilating into antiquark. As each of the gluons from surgery. Low molecular weight dextran is three gluons in much the same way that upsilon decay will on average carry an antigenic but there is no evidence for this positronium disintegrates into three energy of nearly 3 GeV, gluon jets can be with clinically-used dextran, although photons. The gluons of course have to expected there. The three gluons should allergic reactions occasionally occur. evolve into colourless hadrons later. The emerge symmetrically with 120° angles Various dextrans in the molecular weight glueball may lurk among such hadrons. between one another, and there is some range of 40,000-110,000 are used One interesting decay mode is when J/tp preliminary evidence for such events from depending on the balance of effect goes into an energetic photon plus hadrons. PLUTO (CERN Courier 19, 108; 1979). desired. Here the heavy quark-antiquark pair in the Another interesting possible configuration The Chinese work is from the Institute of J/tp annihilate into two gluons and a is one in which an energetic gluon dashes Organic Chemistry in Shanghai, one of the photon. The two gluons could resonate off to one side leaving two less energetic three big polymer research groups in into a glueball in which case the photon will collinear ones opposite. This will lead to China. They describe the production of be highly monochromatic. Experiments two jets opposite each other that are sodium carboxymethyl amylose by done by the PLUTO group at the German asymmetrical. According to a recent carboxymethylation of amylose from corn storage ring DORIS have yielded good suggestion (Roy & Walsh Phys. Lett. 788, starch (Acta Chimica Sinica 36, 49 (1978). quality data for precisely this situation. 62; 1978), the energetic gluon can now The molecular weight of the product was They rule out the existence of any glueball easily induce the creation of a gluon pair characterised by ultracentrifugation, up to a mass of 1.2 GeV, thereby from the vacuum and capture one of its solution viscometry, fractional demolishing the lighter than 1 Ge V glueball members to form a glueball. The latter precipitation and osmotic pressure. Using of the MIT bag model. should show up as a prominent, not very 1"C-labelled carboxymethylation followed Turning to the much heavier upsilon, the unstable resonance in one arm of the two by hydrolysis and paper chromatography three gluons from its decay are expected to jets and should disappear off the upsilon the reaction was shown to occur primarily generate jet-like hadronic fragments. mass. Quantitative estimates, albeit hand­ on the 2-oxygen. The degradation rate of Normal electron-positron annihilation waving, have been made and look the polymer in blood decreases with into hadrons by way of a quark-antiquark extremely favourable for the production increasing carboxymethylation. A 5o/o pair) above 6 GeV produces two and detection of glueballs in this manner, if solution of the polymer (molecular weight symmetrical jets opposite each other. This they exist at all. D 60,000, 0.4 carboxyl methyl groups per saccharide) in 0.9% saline is now being tested in animals. It maintains blood Polymers for blood replacement volume for 6 h, is 90% lost in 24 h and is said to lack the immunological reactions of from Paul Calvert dextran. A possible snag, however, is that SYNTHETIC blood volume expanders are osmotic pressure balance as the electrolytes similar charged polymers are reported to sometimes used in cases of extensive pass readily across membranes into the enhance clumping (see Rickets op.cit.) bleeding or burns where much plasma has tissues. It is necessary also to restore the This work is interesting in the Chinese been lost, or in cases of shock, where colloidal osmotic (oncotic) pressure context for a number of reasons. It is a contraction of the capillaries increases normally provided by serum albumin piece of careful, thorough polymer science. blood pressure so that water is lost to the which cannot cross the membrane and so It describes the development of a new tissues, the blood thickens and circulation balances the osmotic pressure of the material from an available resource to ceases. Restoration of normal volume can macromolecular cell contents. In practice it replace the complex fermentation process be achieved by natural plasma, solutions of does not seem to be agreed whether needed for dextran. The work is original, plasma proteins or by solutions of polymers polymeric (or 'colloidal') solutions work whereas much of polymer science in China such as dextran. Where blood or plasma better than salt solutions but they are has been devoted to reproducing Western are readily available the main reason for certainly better in principle (see Pennell, in materials from patents. Also the work was using a synthetic expander is to avoid the Bib/. Haemat. 29, 883; 1968). done between 1961 and 1964 and has risk of hepatitis. On the other hand, in Solutions of a range of water-soluble waited 15 years to be published. It shows countries where blood supplies and storage polymers have been tried as volume that a relatively modest project can and separation facilities are more limited, expanders. The chief requirements are that produce something adapted to local needs. synthetic substitutes should be more the polymer is of sufficiently high Most Western interest in this area seems important. So, recently published Chinese molecular weight to prevent its loss to be in the more dramatic problem of an work on a volume expander derived from through the kidneys, that it resists artificial blood substitute capable of corn starch is of interest as an application degradation and causes no harmful carrying oxygen, particularly for organ of science to the needs of a developing reactions. Dextran is chiefly used but storage. Geyer (Drug Design VII (ed. country. hydroxyethyl starch has had successful Ariens) Academic Press, 1976), has Blood has such diverse functions that it is clinical trials and polyvinylpyrrolidone has reviewed these with particular regard to difficult to imagine a completely been tested (Ricketts, Brit. J. Anaesth. emulsions of perfluorochemicals. With satisfactory substitute. The role of a 45,958; 1973). Dextran has been used for these he was able to replace completely the volume expander is simply to maintain the about 30 years and its side effects are well blood of rats so that they survived in 100% correct water balance between blood and studied (Gruber & Messmer, Prog. Surg. oxygen for 10 days until their red cells the tissues and to allow continued IS, 49; 1977); Gronwall et al., Bib/. regenerated and they could be returned to transport of nutrients and gases. The water Haemat. 29, 874; 1968). High molecular air. Interestingly, these bloodless rats balance is determined by the osmotic weight dextrans cause clumping of red cells could also survive in 10% carbon pressure between blood and tissues, and (rouleaux formation) though, interestingly monoxide. Cell-free haemoglobin the hydrostatic pressure difference. Lost from the colloid science viewpoint, solutions have also been used for blood volume can be restored by addition of an molecules of low molecular weight lower replacement but they are degraded and isotonic electrolyte solution such as even the natural degree of clumping. must be continually transfused. There is Ringer's but this does not give the correct Reduced clumping leads to lower blood obviously potential here for an oxygen­ Paul Calvert is a Lecturer in the School of viscosity, promotes blood flow and chelating polymer but a suitable molecule Molecular Sciences, University of Sussex. exchange of nutrients with tissues and so is does not yet seem to be available D

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