The acute chest syndrome in sickle cell disease: incidence and risk factors. The Cooperative Study of Sickle Cell Disease.

The acute chest syndrome (ACS), a pneumonia-like illness in sickle cell patients, is one of the most frequent causes of their morbidity and hospitalizations. Repeated ACS events may predict the development of chronic lung disease. ACS is reported as a frequent cause of death in these patients. We examine here the incidence and risk factors of ACS in 3,751 patients with sickle cell disease who were observed prospectively for at least 2 years (19,867 patient-years [pt-yrs]) as part of a multicenter national study group. The ACS, defined by a new pulmonary infiltrate on x-ray, occurred at least once in 1,085 patients (2,100 events). ACS incidence was higher in patients with homozygous sickle cell disease (SS; 12.8/100 pt-yrs) and in patients with sickle cell-beta(0) -thalassemic (9.4/100 pt-yrs), and lower in patients with hemoglobin (Hb) SC disease (5.2/100 pt-yrs) and patients with sickle cell-beta(+) thalassemia (3.9/100 pt-yrs). alpha-Thalassemia did not affect the rate of ACS incidence in SS patients. Within each Hb type the incidence was strongly but inversely related to age, being highest in children 2 to 4 years of age (25.3/100 pt-yrs in SS) and decreasing gradually to its lowest value in adults (8.8/100 pt-yrs in SS). In SS children (< 10 years of age), we documented an age-related within-person reduction in ACS attack rates. Adults with a higher ACS rate had a higher rate of mortality (from all causes) than those with low ACS rates. This increased rate of mortality might also have contributed to the decline in ACS rate with age. In multivariate analysis, other factors affecting incidence in SS patients were degree of anemia (lower ACS rates in patients with lower steady-state Hb levels) and fetal Hb (lower rates in patients with high fetal Hb). There was also a positive association between ACS rate and steady-state leukocyte count. The relationship of ACS rate to higher steady-state Hb levels in SS patients is unexplained but might be caused by increased blood viscosity.

Toothbrushing and transient bacteremia in patients undergoing orthodontic treatment.

This study was made to determine whether and to what extent bacteremia occurred after toothbrushing in patients undergoing orthodontic treatment with fixed appliances. Twenty patients were selected, all with negative history of heart or hematologic disorders. These patients had not taken antibiotics or had a history of a cold in the previous 30 days. Blood samples of 20 ml were drawn before and 5 minutes after brushing. The immune status of the patients was tested by measurement of isohemagglutins and immunoglobulin levels. Blood samples were incubated in paired culture bottles containing trypticase soy broth (TSB) with an agar paddle and Columbia broth. All samples taken before brushing were negative for bacteria. Five of the 20 patients (25% of the sample) had positive blood tests after brushing. Both anaerobic and aerobic bacteria were identified from the blood samples. Those patients who were found to have a bacteremia did not display poor oral hygiene.

Pitted red cell counts in Nigerian children with sickle cell anemia: correlation with age and splenic size.

Using direct interference phase-contrast microscopy (Normansky Optics), pit counts were performed on 32 HbSS patients, aged 3 to 17 years. The influence of age and splenic size on counts were also investigated. Nine HbSS and 15 HbAA age and sex-matched, healthy individuals served as controls. The mean +/- SD counts in the three groups were 11.1 +/- 9.1%, 1.7 +/- 1.4% and 1.8 +/- 1.7%, respectively. The older SS patients tended to have higher values, but the linear correlation with age was not impressive (r = 0.28). Seventeen (53.1%) patients had counts greater than 10%, while 8 (25%) had less than 3.5%. Five patients with gross splenomegaly had a mean count of 4.3 +/- 1.9%, significantly lower than the figure of 12.3 +/- 7.9% for the patients without splenomegaly (P less than .001), demonstrating retained reticulo-endothelial function in such patients.

The significance of gallstones in children with sickle cell anemia.

Infection is the most common cause of high morbidity, hospitalization, and mortality in children with sickle cell anemia. In this study of pediatric sickle cell anemia patients, aged 1 to 19, we explore the hypothesis that gallstones (usually pigment stones) create a nidus of infection, predisposing the affected patients to high morbidity. Our study involved 86 children with sickle cell anemia at the Howard University Center for Sickle Cell Disease, who had been followed at the clinic for a total of 602 patient years. Review of their records revealed that patients with gallstones had a mean number of 10.24 hospitalizations and 25.35 ambulatory visits; those without gallstones had a mean number of only 4.26 hospitalizations and 13.41 ambulatory visits. In children with sickle cell anemia and gallstones, elective cholecystectomy (or, in the future, cholelithotripsy) could reduce the high morbidity caused by infection.

Model for phase III autografts of epidermal cells cultured on a collagen-proteoglycan biomatrix.

The primary aim of this study was to develop a model system that uses epidermal cells (keratinocytes and accessory pigmented cells) cultured on a reconstituted basement membrane biomatrix for use in conjunction with type I collagen as a replacement dermis-epidermis in the treatment of recurrent ulcerative lesions. Type I collagen sponges (Collistat) have been shown to promote rapid healing of leg ulcers but with extensive scarring (Reindorf et al, 1989). Dermatome sections from patients undergoing elective plastic surgery were treated with dispase to dissociate epidermis from dermis, the inner epidermal cells were then dissociated with trypsin-EDTA and plated on the biomatrix. A 4 cm2 skin specimen yielded approximately 10 to 12 million inner epidermal cells. These cells were plated at a density of 500,000 cells/cm2, thereby covering an area of 20 to 24 cm2. At 24 hours attached cells were dispersed primarily in monolayers, and by day 3 most of the epidermal cells reassociated into bi- or multilayered aggregates. Cells containing melanin granules were distributed in the basal to middle layers of the aggregates and persisted throughout the culture period (up to 14 days).

Rapid healing of sickle cell leg ulcers treated with collagen dressing.

Chronic leg ulcers in sickle cell anemia occur mainly around the ankles. The prevalence is up to 75% in adults. These ulcers are painful and debilitating, yet medical treatment is unsuccessful. Surgical treatment consists of repeated skin grafting procedures, which eventually deplete the patient's available donor sites. Thus, in vitro generation of human epidermal autograft for potential treatment of leg ulcers in sickle cell anemia was initiated. However, because epidermal cells need a supporting matrix in order to be applied to the ulcer, the authors decided to assess the independent effect of a collagen matrix alone in promoting healing of sickle cell leg ulcers. Collistat (Hellistex, Inc) dressing was applied directly to the ulcers. The ulcers were reviewed every 2 weeks, and the dressing reapplied every 4 weeks. Collagen matrix caused the chronic ulcers to heal completely in fewer than 3 months. This encouraging performance of collagen alone should be greatly enhanced by the in vitro epidermal autograft.

Lung function in sickle cell hemoglobinopathy patients compared with healthy subjects.

Previous studies of lung function tests performed on patients with sickle cell disease have shown a restrictive ventilatory defect, usually a diffusion defect, and mild hypoxia at rest. The present study was undertaken to explain the pathophysiology of these changes and to extend these studies to include functional measurements not reported previously.Lung function studies were performed at rest and during treadmill walking on 66 patients with sickle cell anemia and on 16 healthy control subjects. Patients had restrictive ventilatory defects, decreased lung compliance, and uneven ventilation-perfusion ratios. These abnormalities caused an increased alveolar-arterial oxygen tension difference that caused hypoxemia. The diffusion defects were because of the sickle cell disease.Carboxyhemoglobin levels were increased in patients with sickle cell disease. This increase may be caused by a combination of factors, including increased cigarette smoking, hemolysis, and preferential survival of red blood cells that contain carbon monoxide and which do not sickle. During treadmill walking, the patients with sickle cell disease showed a decreased work tolerance caused by impaired oxygen delivery. The anaerobic threshold is reached sooner in patients with sickle cell disease and may also account for the limitations in work capacity of these patients.

Electron microscopic studies of the intracellular polymerization of sickle hemoglobin.

Transmission electron microscopy has been used to study intracellular sickle hemoglobin polymer in unfractionated cells from the arterial and venous blood of patients and after external deoxygenation. We detect polymerized hemoglobin in up to 10% of the cells in the venous circulation, especially in cells that are "cigar-shaped" and appear to be irreversibly sickled. We could not see well-defined polymer in mixed arterial samples; nevertheless, we found electron opaque spots, which could be ferritin granules, hemosiderin, or small aggregates of hemoglobin S. However, upon sequential chemical deoxygenation using 1.0% sodium metabisulphite, polymer formation was seen at oxygen saturation values of 75%-85%. Cells that were physically deoxygenated using gas mixtures containing nitrogen-carbon dioxide-oxygen mixtures were found to contain distinct polymers of deoxyhemoglobin S at oxyhemoglobin saturation values of 50%-75%. As deoxygenation increases, we detect short, randomly arranged polymer in a loose network, with occasional long polymers. Upon further deoxygenation, the length and number of polymer forms increased. Between 0% and 50% saturation, most erythrocytes were full of long, parallel, closely packed polymers that tend to align and run parallel to the cell membrane. In both chemical and physically deoxygenated blood samples, cells were seen at 50%-75% oxyhemoglobin saturation that retained their normal biconcave disc shape, although they contained significant amounts of polymer. The structural changes in sickle erythrocytes seen in vitro due to physical or chemical deoxygenation of cells, may reflect in vivo intracellular changes in the sickle cell patient.

Toothbrushing and transient bacteremia in patients undergoing orthodontic treatment.

A study was made to determine the extent of bacteremia experienced by patients undergoing orthodontic treatment with fixed appliances during periods of routine oral hygiene--namely, brushing the teeth. Sixteen orthodontic patients made up the population--11 who practiced good oral hygiene and five who demonstrated poor oral hygiene. Blood was drawn aseptically from the median cubital vein of the subjects before and 15 minutes after brushing the teeth. An aliquot of each blood specimen was added to separate blood culture bottles and incubated at 37 degrees C for a period of up to 5 days. Blood was also used to determine the immune status of the subjects. Anaerobic bacteria were recovered from the blood of nine of the 16 patients studied; aerobic bacteria were not recovered. A negative blood culture before brushing and positive blood culture after brushing were expected but did not occur. Some subjects showed bacteremia before brushing and a negative blood culture after brushing. Others showed bacteremia before and after brushing. The unexpected results could be attributed to the patients eating and/or brushing before starting the test. The study showed the capacity of specific anaerobic bacteria to remain in the bloodstream for a 15-minute period. It also demonstrated a presence of bacteria in the bloodstream before the test began.

Perfluorocarbon compounds: effects on the rheological properties of sickle erythrocytes in vitro.

The effects of oxygenated perfluorotributylamine (Fluosol-43) on the rheological properties of sickle (HbSS) erythrocytes have been determined by means of microviscometry and positive pressure cell filtration. Incubation of deoxygenated sickled erythrocytes (pO2 congruent to 30 mmHg) with oxygenated Fluosol-43 reduced the percentage of sickled erythrocytes from about 63 to 33%. Deoxygenation of 40% suspension of sickle erythrocytes in autologous plasma increased the viscosity by about 160% at shear rate of 1.15 sec-1. Incubation of the deoxygenated sickled erythrocytes with oxygenated Fluosol-43 significantly reduced the viscosity at the low shear rates. Filtration of 0.2% suspension of deoxygenated sickle erythrocytes through capillary-sized Nuclepore filters showed high resistance at low flow rates. Oxygenated Fluosol-43 increased the deformability of HbSS erythrocytes and thereby reduced the resistance at flow rates less than 1 ml/min. These data suggest that perfluorocarbons may be useful in reducing the propensity of hemoglobin S polymerization and sickling and thereby prevent tissue infarction in vaso-occlusive crisis. Therefore, the concept of examining the potential application of perfluorochemicals for alleviating severe vaso-occlusive events may be useful.

Nephrotoxic effects of oxygen transport media in the isolated rat kidney.

Perfusion of isolated kidneys from rats demonstrated the following nephrotoxic effects of Fluosol-DA: decreased glomerular filtration rate (GFR), urine flow rate (UFR), and fractional reabsorption of potassium (FrK+) (P less than 0.01). Fluosol-DA perfusions were at flow rates about equal to the physiologically normal rodent renal plasma flow rate of 4 ml/min. Stroma-free hemoglobin (SFH) perfusions, also at 4 ml/min, were associated with physiologically normal renal functions, as were those of control Krebs-Ringer bicarbonate (KRB) perfusions at 32 ml/min.

Sickle Lepore hemoglobin identified in a black American infant.

An integrated newborn infant screening, follow-up testing, and counseling service for hemoglobinopathies creates opportunity for early medical management of disease processes, assistance to parents in developing coping strategies, and educational counseling about recurrence risks in subsequent pregnancies. These objectives were operative in a case of sickle Lepore hemoglobin identified through a newborn infant screening service. The initial screening test was reported as Hb AS. Follow-up electrophoresis on cellulose acetate was compatible with Hb SS, but in citrate acid agar gel there were major and minor zones of S and A mobility, respectively. This and other hematologic parameters in both the child and his father were compatible with a sickle Lepore phenotype. This was supported by a tryptic peptide map of the purified variant hemoglobin from the father. Without a follow-up testing and counseling service, this case would probably have been missed until manifestation of clinical phenotype.

Perfluorocarbon enhancement of heterologous red cell survival: a reticuloendothelial block effect?

The intravascular survival of human erythrocytes transfused to primate animals was prolonged by infusing the recipients with a perfluorocarbon red cell substitute (Fluosol DA). This effect is probably due to transient block of the animals' reticuloendothelial system by the perfluorocarbon emulsion. Perfluorocarbon compounds could be used to study the role of reticuloendothelial function in the immune destruction of red cells.

The nephrotic syndrome in Ghana: clinical and pathological aspects.

Clinical and pathological features of the nephrotic syndrome were studied in 36 adults and 25 children in Ghana. No evidence was found to implicate Plasmodium malariae as a cause and in the majority of patients the aetiology was not identified. Minimal change glomerulonephritis responsive to steroids was demonstrated in 14/25 children and 5/36 adults which was surprising as this lesion has been reported only rarely from tropical Africa. The other major histological lesions were focal segmental glomerulosclerosis (12/61), diffuse proliferative glomerulonephritis (11/61) and membranous glomerulonephritis (9/61).