Infection in immunocompromised patients

Infection is a common cause of morbidity and mortality in immunocompromised patients for whom diagnosis and management require scrupulous attention to detail and a continuing awareness of the micro-organisms causing infection in a particular environment in different groups of patients. Although uncommon and relatively non-pathogenic organisms may be the cause of infection in these patients most are caused by recognised pathogens. The present review concentrates on infection in the immunocompromised as seen in the United Kingdom.     

New options for untreatable coronary artery disease: angiogenesis and laser revascularization

Some patients with severe symptomatic coronary artery disease despite maximal medical therapy are not eligible for bypass surgery or percutaneous coronary intervention, but may be eligible for two newer therapies: therapeutic angiogenesis with growth factors and transmyocardial laser revascularization.     

Accelerated immune red cell destruction in the absence of serologically detectable alloantibodies

Two patients are described in whom clinically significant red blood cell alloantibodies could be demonstrated only by in vivo 51chromium (51Cr) survival studies. The first patient had experienced a severe delayed hemolytic transfusion reaction to four units of crossmatch compatible blood. Serial phenotype studies suggested the presence of a serologically undetectable anti-c (hr') antibody. 51Cr survival of c- positive red blood cells was one per cent at 24 hours, while survival of c-negative red blood cells was 80 per cent at 24 hours. The second patient had multiple red blood cell alloantibodies. An anti-c antibody was suspected but could not be convincingly demonstrated by in vitro techniques. 51Cr survival of c-positive red blood cells, however, was 57 per cent at 24 hours and 17 per cent at 48 hours. 51Chromium red blood cell survival studies should be considered whenever an unexplained hemolytic transfusion reaction occurs, or when an expected red blood cell alloantibody cannot be demonstrated by in vitro laboratory studies.     

A simplified, colorimetric micromethod for xylose in serum or urine, with phloroglucinol.

We have developed a simplified xylose assay procedure that requires only 10 min and requires 50 microL of serum or 5 microL of urine. The reaction with phloroglucinol is more sensitive than the classic p-bromaniline color reaction, and requires only 4 min of heating for color development. A single reagent is mixed with the specimen directly, without prior protein precipitation. Analytical recovery of xylose added to serum was quantitative; precision studies resulted in a between-day coefficient of variation of 5.2%. Glucose, which has significant potential for interference in most other xylose procedures, reacts under the test conditions only to the extent of 70 mumol of apparent xylose per liter for a 5.5 mmol/L solution of glucose. The new procedure has been valuable in the assessment of malabsorption, especially in children and infants, where serum xylose is the preferred measurement.     

The effect of prestorage irradiation on posttransfusion red cell survival

Transfusion-associated graft-versus-host disease (TA-GVHD) may occur whenever immunologically competent allogeneic lymphocytes are transfused to an immunocompromised recipient. Irradiation of blood components eliminates the risk of TA-GVHD but may damage the cellular elements in the transfused component, particularly if the cells are stored for prolonged periods in the irradiated state. To study the effect of irradiation on long-term storage of red cells, AS-1 red cells from eight normal subjects were prepared on two occasions. On one occasion, the units were stored as standard AS-1 red cells for 42 days at 4 degrees C; on the other, they were exposed to 3000 cGy radiation within 4 hours of collection and then were stored as AS-1 red cells for 42 days at 4 degrees C. The donations were at least 12 weeks apart. Irradiated units demonstrated significant elevations in poststorage plasma hemoglobin (Hb) (623 +/- 206 vs. 429 +/- 194 g/dL [6230 +/- 2060 vs. 4290 +/- 1940 g/L], p less than 0.02) and plasma potassium (78 +/- 4 vs. 43 +/- 9 mEq/L [78 +/- 4 vs. 43 +/- 9 mmol/L], p less than 0.01) and significant decreases in red cell ATP (1.9 +/- 0.2 vs. 2.1 +/- 0.3 microM/g Hb, p less than 0.04) and 24-hour posttransfusion red cell recovery (68.5 vs. 78.4%, p less than 0.02), as compared to nonirradiated units. It can be concluded that irradiation with 3000 cGy damages red cells and that long-term storage in the irradiated state may enhance this damage. Red cells should not be stored for 42 days after irradiation with 3000 cGy.     

Haemodynamic Studies During the Management of Severe Tetanus

Detailed invasive haemodynamic studies were performed in 27of 32 patients with severe tetanus. Nineteen had severe uncomplicatedtetanus and eight had associated major complications, chieflyinfection and pulmonary complications. The results were comparedwith those obtained from 15 healthy male volunteers who servedas controls. There were two deaths in 32 patients (mortality6.25 per cent). Severe tetanus without major complications wascharacterized by a high output hyperkinetic circulatory statewith tachycardia (heart rate 131 (19.2) beats/minute), increasedstroke volume index (43.1 (10.7) ml/m²), increased cardiac index(5.48 (0.94)1/min/m²) and a normal left ventricular stroke workindex (60.5 (15.9) g/m/m²). Volume loading demonstrated a significanthaemodynamic response and increased vascular capacitance. Evenso the maximum percent rise from baseline values of these indicesafter volume load was significantly higher in controls (p <0.001). Autonomic cardiovascular disturbances affected bothsympathetic and parasympathetic activity. Hypertension and tachycardiaalternating with hypotension and bradycardia were related tosudden fluctuations in systemic vascular resistance. Our studiessuggested some degree of myocardial dysfunction in patientswith severe uncomplicated tetanus. The haemodynamics of severetetanus were masked and altered by complicating infection, pneumonia,and atelectasis.     

A model for involutional bone loss

Bone mass of the total skeleton and distal radius were measured by in vivo neutron activation analysis and single photon absorptiometry, respectively, in 403 healthy white women and 151 healthy white men. In addition, the density of L-2 to L-4 (bone mineral content of the spine [BMCs]) was measured by dual photon absorptiometry in 159 of these women and in 56 women with the vertebral crush fracture syndrome. The rate of loss of total body calcium (TBCa) and bone mineral content of the radius (BMCr) was linear in men and was slower than in women. The best fit for TBCa and the bone mineral content of the distal radius and spine as a function of age in women was with a two-phase regression. The TBCa and BMCr could be used as well as BMCs to identify women with crush fractures. The ratios of BMCs/TBCa, BMCs/BMCr, and TBCa/BMCr did not differ among women with crush fractures and age-matched normal individuals. Our data do not support the hypothesis that women with vertebral crush fractures have preferential loss of spinal bone.