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contribute to the early diagnosis of acute cardiac graft rejection. A extensive study is underway to assess the sensitivity and the specificity of this approach, which offers low cost and little invasiveness. Probably, NMR indices recorded longitudinally cannot by themselves diagnose rejection, and variations in glycosylated residues must be interpreted in the clinical context. They reflect modifications in glycosylation, easily detected by NMR spectroscopy, in various pathological states, including immunological activation related to graft rejection.

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Biological and Medical Magnetic Resonance Centre (URA CNRS 1186), Faculty of Medicine, 13005 Marseille, France, and Cardiac Surgery Service, CHU de la Timone, Marseille

H. PONT J. VION-DURY M. KRIAT A. MOULY-BANDINI M. SCIAKY P. VIOUT S. CONFORT-GOUNY T. MESSANA M. GOUDART J. R. MONTIÈS P. J. COZZONE

Eugène M, De Certaines J, Le Moyec L, et al. Spectroscopie du plasma par résonance magnétique nucléaire du proton au cours de la transplantation cardiaque. C R Acad Sci Paris 1988; 307: 41-45. 2 Bell JD, Brown JCC, Nicholson JK, Sadler PJ. Assignment of resonances for "acute phase" glycoproteins in high resolution proton NMR spectra of human blood plasma. FEBS Lett 1987; 215: 311-15. 3. Kriat M, Vion-Dury J, Favre R, et al. Variations of plasma sialic acid and N-acetyl-glucosamine levels in cancer, inflammatory diseases and bone marrow transplantation: a proton NMR spectroscopy study. Biochimie (in press). 1

Assessment of malnutrition in elderly

patients SIR,-We are concerned about the perpetuation of the fallacy that albumin and other proteins can be used as indicators of nutritional status in acutely ill patients. For instance, Delmi et all described nutritional supplementation in 59 elderly patients with fractures of the femoral neck who, they claimed, had nutritional deficiencies on admission. Their assessment included morphological measurements and estimation of plasma retinol binding protein. Vellas et alz reported nutritional assessment of fallers andnon-fallers admitted to their geriatrics department. They included measurement of retinol binding protein, prealbumin, transferrin, and albumin. Although few would question that poor nutritional status can contribute to morbidity in elderly individuals (and may even lead to predisposition to fall), there is clear evidence that so-called biological nutritional markers do not indicate nutritional status shortly after onset of acute illness or trauma. Albumin, transferrin, prealbumin, and retinol binding protein are all negative acute-phase proteins.3 Their plasma concentrations fall after any episode resulting in a rise in release of cytokines. The use of these proteins as nutritional markers is therefore limited to occasions in which the acute-phase response (APR) has been excluded-eg, by the finding of normal concentrations of Creactive protein (CRP), serum amyloid A, or o-antichymotrypsin. Caeruloplasmin, which is a positive acute-phase protein, has the same plasma concentration in fallers as in non-fallers in Vellas and colleagues’ study. Caeruloplasmin is not nearly as sensitive an indicator of APR as is CRP-indeed, it is probably one of the least sensitive acute-phase proteins.4 Retinol binding protein concentration falls very rapidly during APR, as does prealbumin.5 This may explain the low concentration seen on admission in Delmi’s group and in fallers in Vellas’ study. The reduced vitamin A values in these two groups thus probably result from decreased retinol binding protein and prealbun-fin concentrations. The prompt decrease in concentration of many plasma proteins during APR could be attributable to increased vascular permeability. The transcapillary escape rate (TER) of albumin6 has been estimated to be about 120% of the intravascular pool per day in controls (compared with a synthesis rate of only 10% per day)7 TER is raised in patients undergoing cardiac surgery, and in those with septic shock or cancer cachexia.7 Since TER is some ten times

that of synthesis and catabolic rates of albumin,8 it is obvious that, initially, TER will be of overriding importance in the measurement of albumin concentration. Delmi et al assign normal admission and low day-14 plasma albumin values to initial dehydration and subsequent rehydration in malnourished patients. Although this may be a factor, we sugggest that additionally there has been an initial increased loss of proteins to the extravascular spaces and that recovery from this will be delayed by diminished synthetic rates-resulting from both APR’ and poor nutritional status. Consequently, we believe that it is a misconception to ascribe these low concentrations of plasma proteins to malnourishment. Neither group of workers included the measurement of haemoglobin in their nutritional assessment. Keys at el9 showed many years ago that haemoglobin concentration decreased in proportion to the reduction in body weight during protein-energy malnutrition whereas plasma protein concentrations did not change. If measurement of haemoglobin is excluded because of possible haemorrhage into fracture sites, measurement of plasma proteins should be excluded for the same reason.

Information about the time of fall and time of blood sampling and concomitant measurement of a sensitive acute-phase protein such as CRP would allow accurate assessment of the reasons for the decreases in plasma protein concentrations. Department of Chemical Pathology, Charing Cross and Westminster Medical School, London W6 8RP, UK

ADAM FLECK GEOFFREY SMITH

M, Rapin C-H, Bengoa J-M, Delmas PD, Vasey H, Bonjour J-P. Dietary supplementation in elderly patients with fractured neck and femur. Lancet 1990;

1. Delmi

335: 1013-16. 2. Vellas B, Conceicao J, Lafont C, et al. Malnutrition and falls. Lancet 1990; 336: 1447. 3. Fleck A. Acute phase response: implications for nutrition and recovery. Nutrition

1988; 4: 109-17. Whicher JT, Dieppe PA. Acute phase proteins. In: Clinics in immunology and allergy: laboratory investigation of immunological disorders, vol 5. Philadelphia: WB Saunders, 1985: 425-45. 5. Moody BJ. Changes in the serum concentrations of thyroxine-binding prealbumin and retinol-binding protein following burn injury. Clin Chim Acta 1982; 118:

4.

87-92.

Parving HH, Gyntelberg F. Transcapillary escape rate of albumin and plasma volume in essential hypertension. Circ Res 1973; 32: 643-51. 7. Fleck A, Raines G, Hawker F, et al. Increased vascular permeability: a major cause of hypoalbuminaemia in disease and injury. Lancet 1985; i: 781-84. 8. Fleck A. Computer models for metabolic studies on plasma proteins. Ann Clin 6.

9.

Biochem 1985; 22: 33-49. Keys A, Brozek J, Henschel A, Mickelson O, Taylor HL. The biology of human starvation. Minneapolis: University of Minnesota Press, 1950.

Vertical transmission of HIV SiR,—The European Collaborative Study (Feb 2, p 253) reports transmission rate of HIV infection of about 13%, which is lower than that reported in most other studies. Two prospective investigations from African countries showed a vertical a vertical

transmission rate of 39%. The contributors to the European report suggest several good reasons for upward bias in other studies, but do not mention the possible contribution of chorioamnionitis to the increased rate of transmission reported in the African studies. The higher rate of transmission in African countries might be related to the greater proportion of mothers with symptomatic HIV disease, and a higher loss of babies to follow-up. Breastfeeding could be a factor, but it should be noted that two-thirds of children apparently escaped infection with HIV despite breastfeeding for 18-24 months. I suggest that chorioamnionitis may also be an important factor that raises the risk of transmission of HIV to the fetus, especially in African countries. Since research shows that most HIV-infected individuals, whatever their clinical status, have circulating infectious HIV in plasma,3 it is noteworthy that the risk of vertical transmission is moderately low. A healthy placenta is presumably an important factor in the prevention of intrauterine HIV transmission. Chorioamnionitis is more common in African countries than in developed countries. Infection with Candida, Ureaplamw urealyticum, Mycoplasma honunis, and other pathogenic bacteria can take place through intact metrbranes, and result in clinically silent,

Assessment of malnutrition in elderly patients.

793 contribute to the early diagnosis of acute cardiac graft rejection. A extensive study is underway to assess the sensitivity and the specificity o...
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