Prospective RBC phenotype matching in a stroke-prevention trial in sickle cell anemia: a multicenter transfusion trial

BACKGROUND

Most sickle cell anemia patients undergo transfusion therapy to prevent complications. The Stroke Prevention Trial in Sickle Cell Anemia showed that transfusion therapy is effective in the primary prevention of stroke. Despite its efficacy, transfusion therapy is limited by alloimmunization. The purpose of this study was to determine if a multicenter trial could implement a transfusion program utilizing phenotypically matched blood to reduce alloimmunization.

STUDY DESIGN AND METHODS

One hundred thirty children underwent RBC phenotyping and antibody screening with review of blood bank records. The protocol required use of WBC-reduced RBCs, which were matched for E, C, and Kell. Monthly alloantibody testing and review of transfusion forms were performed to determine compliance and the occurrence of any adverse events.

RESULTS

Patient RBCs expressed a low frequency of Kell (2%), E (20%), and C (25%) antigens. Sixty-one patients received 1830 units. Ninety-seven percent of all units were WBC reduced. Only 29 units were inadvertently not matched for E, C, and Kell. Five patients (8%) developed a clinically significant alloantibody. Four developed a single antibody to E or Kell. Three patients (5%) developed a warm autoantibody. There were 11 transfusion reactions and 8 transfusion-associated events. Transfusion reactions included 6 febrile reactions (0.33%/unit), 3 allergic (0.16%/unit), and 2 hemolytic (0.11%/unit). Associated events included 4 episodes of hypertension (0.22%/unit), 3 crises (0.16%/unit), and 1 transient ischemic attack (0.05%/unit).

CONCLUSION

This is the first multicenter study to show that extended RBC phenotyping can be implemented nationwide. Compared to studies, the alloimmunization rate dropped from 3 percent to 0.5 percent per unit, and hemolytic transfusion reactions dropped by 90 percent. It is recommended that all transfused sickle cell anemia patients be antigen matched for E, C, and Kell. Patients should be closely monitored during transfusions to avoid preventable risks.

Pathogenesis of SIV pneumonia: selective replication of viral genotypes in the lung

Lymphocytic interstitial pneumonia of HIV-infected individuals and SIV pneumonia of macaques are both characterized by diffuse infiltration of the lungs with lymphocytes, plasma cells, and macrophages. This study was undertaken to determine whether there are specific, macrophage-tropic genotypes that selectively replicate in the lung of macaques with SIV pneumonia, as in SIV encephalitis. Using a rapid, reproducible SIV/macaque model of AIDS, 11 pig-tailed macaques were intravenously inoculated with an immunosuppressive viral strain, SIV/DeltaB670, and a macrophage-tropic molecule clone, SIV/17E-Fr, and euthanized at 3 months postinoculation. All 11 macaques had severe (6 macaques) or moderate (5 macaques) pneumonia. To identify the viral genotypes that were replicating in the lung parenchyma, bronchoalveolar lavage (BAL) cells, and peripheral blood mononuclear cells (PBMC) of each macaque, RNA was isolated and the SIV env V1 region was amplified, cloned, and sequenced. Lung homogenates and BAL cells contained a more limited repertoire of viral genotypes than PBMC. SIV/17E-Fr was the major genotype in the lungs of 5 macaques and in BAL cells of 6 macaques. The remainder of the macaques had SIV/17E-Fr and the macrophage-tropic strains of SIV/DeltaB670 clones 2 and 12. In contrast, SIV/17E-Fr was the predominant strain in the PBMC of only 3 of 11 macaques. The viral strain that predominated in PBMC was rarely the strain that predominated in the lungs (only 3 of 11 macaques). The severity of pulmonary lesions did not correlate with the levels of viral RNA in lung homogenates or in plasma. However, when only SIV/17E-Fr was expressed in the lung, the viral load in the lung was significantly higher (P = 0.016) than when SIV/DeltaB670 was present alone or in combination with SIV/17E-Fr. These data suggest that SIV pneumonia is associated with selective replication of specific macrophage-tropic genotypes in the lung and that SIV/17E-Fr has a selective advantage for replication in the lung.

In utero AAV-mediated gene transfer to rabbit pulmonary epithelium

In utero intra-amniotic administration of adeno-associated virus (AAV) for treatment of cystic fibrosis (CF) has the potential to be an efficient way to target the rapidly dividing undifferentiated cells of the fetal pulmonary epithelium, while simultaneously treating other tissues involved in CF (such as the intestines), but has never before been studied. Intra-amniotic administration of 1x10(12) particles of AAV-luciferase vector to 110 fetal rabbits at 24-25 days gestation resulted in transgene expression in amniotic membranes, trachea, and pulmonary epithelium. The highest level of transgene expression was found in amniotic membranes. Transgene expression peaked in the lungs 10 days after vector delivery, decreased at day 17, and was no longer detectable after 24 days. The number of pulmonary cells transduced was approximately 1 in 500 and immunohistochemical analysis showed expression in varying cell types, including alveolar cells. Transgene expression was not detected in fetal rabbit intestines, skin or liver, nor in maternal ovaries or liver. Intra-amniotic administration of AAV does not result in the tissue inflammation and fetal loss previously documented with in utero adenoviral administration, and results in high levels of transgene expression in amniotic membranes with lower levels in fetal pulmonary epithelium.

Molecular systematics of Goniodidae (Insecta: Phthiraptera)

The higher level phylogenetic relationships within the avian feather lice (Insecta: Phthiraptera: Ischnocera) are extremely problematic. Here we investigate the relationships of 1 family (Goniodidae), sometimes recognized as distinct within Ischnocera, using parsimony and likelihood analyses of nuclear and mitochondrial DNA sequences. These data support monophyly for a restricted definition of traditional Goniodidae, but recognition of this family would result in paraphyly of the large heterogeneous family Philopteridae. We show that the New World Chelopistes is not related to other members of Goniodidae, despite similarities in morphology, but rather is the sister taxon to Oxylipeurus. Within Goniodidae, genera are divided into those occurring on Galliformes (the Goniodes complex) and those occurring on Columbiformes (the Coloceras complex). Within the well-sampled Coloceras complex, or Physconelloidinae, several groups are identified. However, traditionally recognized genera such as Coloceras and Phvsconelloides appear to be paraphyletic. Whereas the phylogeny of Goniodidae reflects some aspects of host relationships, biogeography also influences coevolutionary history.

Comparison of transcranial color Doppler imaging (TCDI) and transcranial Doppler (TCD) in children with sickle-cell anemia

BACKGROUND

Transcranial Doppler (TCD) has been demonstrated to identify those at highest risk of stroke among children with sickle-cell disease. Based on a randomized clinical trial [Stroke Prevention in Sickle-Cell Anemia Trial (STOP)], which ended in 1997, the National Heart Lung and Blood Division of NIH has recommended TCD screening and chronic blood transfusion based on Nicolet TC 2000 dedicated Doppler (TCD). Studies performed using TCD imaging modalities need to be correlated to that used in the clinical trial to provide information for treatment decisions when screening with TCDI.

OBJECTIVE

To correlate transcranial arterial time-averaged mean velocities obtained from an Acuson Transcranial Doppler Imaging to those obtained using the TCD as the gold standard for treatment decisions based on STOP.

MATERIALS AND METHODS

A total of 29 children with sickle-cell disease, age 3-16 years, were studied at one of two scanning sessions using both techniques and a scanning protocol based on that used in STOP performed and read independently. The average difference in the measured velocities for each arterial segment was tested to determine difference from zero. Differences were compared before and after modifications to the TCDI technique were made to mimic the STOP protocol more closely.

RESULTS

TCDI velocities were generally lower than TCD velocities for the same segment, but the difference was reduced (from 15 % to 10% for the middle cerebral artery) by modifications to the TCDI protocol.

CONCLUSIONS

Measurements using the Acuson system are modestly lower than those obtained with dedicated Doppler using the Nicolet TCD.

Correlation of abnormal intracranial vessel velocity, measured by transcranial Doppler ultrasonography, with abnormal conjunctival vessel velocity, measured by computer-assisted intravital microscopy, in sickle cell disease

The Stroke Prevention Trial has confirmed that utilization of transcranial Doppler ultrasonography (TCD), which examines blood flow in large intracranial vessels, can identify children with sickle cell disease (SCD) who are at high risk of developing a premature stroke. It is not known to what extent the vasculopathy in SCD involves small vessels and whether the abnormalities, if present, correlate with large-vessel vasculopathy. Eighteen children with SCD were examined with TCD to determine middle cerebral artery (MCA) velocity and computer-assisted intravital microscopy (CAIM) to determine bulbar conjunctival vessel velocity during the same visit for vasculopathy correlation. High MCA velocity (≥ 200 cm/sec) was found by TCD in 4 patients who also showed abnormal conjunctival velocity (< 0.2 mm/sec or intermittent trickle flow) by CAIM. Three patients had conditional (≥ 170 cm/sec and < 200 cm/sec) MCA velocity: 2 showed abnormal (trickle) and 1 showed normal conjunctival velocity (1.9 mm/sec). One patient with unmeasurable MCA velocity had abnormal (trickle) conjunctival velocity. Of the remaining 10 patients who had normal MCA velocity, 2 showed abnormal (0.05 mm/sec and 0.1 mm/sec) and 8 showed normal conjunctival velocities (1.1-2.4 mm/sec). The MCA velocities correlated significantly with bulbar conjunctival flow velocities (P ≤ .008, Fisher exact test). A correlation exists between MCA (large-vessel) and conjunctival (small-vessel) flow velocities. CAIM is a noninvasive quantitative technique that might contribute to the identification of SCD patients at high risk of stroke. Small-vessel vasculopathy might be an important pathological indicator and should be further explored in a large-scale study.

Phylogenetic analysis of partial sequences of elongation factor 1alpha identifies major groups of lice (Insecta: Phthiraptera)

As a first attempt to use molecular data to resolve the relationships between the four suborders of lice and within the suborder Ischnocera, we sequenced a 347-bp fragment of the elongation factor 1alpha gene of 127 lice (Insecta: Phthiraptera) as well as outgroup taxa from the order Psocoptera. A number of well-supported monophyletic groups were found but the relationships among many of these groups could not be resolved. While it is probable that multiple substitutions at high divergences and ancient radiation over a short period of time have contributed to the problem, we attribute most of this lack of resolution to the high ratio of taxa to characters. Nevertheless, the sequence data unequivocally support a number of important relationships that are at variance with the conclusions of morphological taxonomy. These include the sister group relationship of Chelopistes and Oxylipeurus, two lice occupying different ecological niches on the same host, which have previously been assigned to different families. These results provide evidence in support of the hypothesis that lice have speciated in situ on the host in response to niche specialization and that this has given rise to convergent morphologies in the lice of different host groups which share similar ecological niches. We discuss our attempts to overcome the limitations of this large data set, including the use of leaf stability analysis, a new method for analyzing the stability of taxa in a phylogenetic tree, and examine a number of hypotheses of relationships based on both traditional taxonomy and host associations.

Stroke prevention and treatment in sickle cell disease

While the problem of stroke in the patients with sickle cell disease (SCD) has been known for more than 75 years, adequate preventive and treatment strategies are just now being tested. Recent data on prevalence and incidence have been obtained from the Cooperative Study of Sickle Cell Disease of more than 4000 patients with SCD observed in 23 US clinical centers over a 10-year period.1 The overall age-specific incidence of first stroke in SCD (homozygous sickle cell anemia) is low (0.13%) at ages younger than 24 months, increasing to just over 1% at ages 2 to 5 years, with only a slight decrement to 0.79% at ages 6 to 9 years. The risk of brain infarction declines until a second peak is seen at ages older than 50 years, when the incidence again increases to nearly 1.3%. Although intracranial hemorrhage does occur in young children with SCD, the risk is low compared with older children and adults. The Cooperative Study of Sickle Cell Disease reported risk factors for infarction to be prior transient ischemic attack, low steady-state hemoglobin values, and rate and recency of episodes of acute chest syndrome, as well as elevated systolic blood pressure. Risk factors for intracranial hemorrhage included low steady-state hemoglobin values and a high leukocyte count. The burden of cerebrovascular disease is even higher if subclinical magnetic resonance imaging (MRI) lesions, presumed to be ischemic, are included. The prevalence of such lesions is more than 22% in patients with SCD, and most of these patients have not reported symptoms, although specialized neuropsychological testing shows lower scores in children with silent lesions on MRI scans. Patients with a history of clinical stroke typically have infarcts in the cortex and deep white matter, whereas silent infarcts tend to be more limited to deep white matter. Common infarction patterns are characterized by wedge-shaped lesions of large-vessel territories; border zone infarctions, particularly of the middle and cerebral artery watershed region; and small punctate lesions of the deep white matter. Fat embolism to the brain and venous thromboses are encountered rarely.

Use of inhaled anti-inflammatory medication in children with asthma in managed care settings

BACKGROUND

Many factors affect use of inhaled therapy in asthma. Relatively little is known about current patterns of use of anti-inflammatory medication in children with asthma and whether variations occur with age and use of bronchodilator medication.

OBJECTIVE

To study the factors associated with dispensing of anti-inflammatory (controller) asthma medication to children in 3 managed care organizations (MCOs).

METHODS

Using automated databases, a 1-year cross-sectional study of children with asthma aged 3 to 15 years cared for in 3 MCOs was used to evaluate the association of age and other factors with controller medication use.

RESULTS

A total of 13 352 children were studied. Significantly fewer children aged 3 to 5 years were dispensed any (> or =1) controller medication than older children (P<.001). Among children dispensed 6 or more beta-agonists, only 39% also received 5 or more controller dispensings, with adolescents significantly less likely than younger children to receive 5 or more controllers (33%; P<.001). Significant differences were seen among MCOs in proportions of patients dispensed controller medication. In a multiple logistic regression model, controlling for frequency of beta-agonist dispensing and MCO, significantly lower dispensing of any controller medication was seen for those aged 3 to 5 years (odds ratio [OR], 0.8; 95% confidence interval [CI], 0.7-0.9) and for girls (OR, 0.9; 95% CI, 0.8-0.96). In contrast, for repeated (> or =5) controller dispensing there were significantly fewer dispensings to adolescents (OR, 0.7; 95% CI, 0.6-0.9) and girls (OR, 0.8; 95% CI, 0.7-0.9).

CONCLUSIONS

There may be differences in the use of preventive asthma medication in children that are affected by age, sex, and health care organization. Few children with frequent symptoms are using controllers regularly, as is recommended by national guidelines.

Impact of inhaled antiinflammatory therapy on hospitalization and emergency department visits for children with asthma

OBJECTIVE

Although the efficacy of inhaled antiinflammatory therapy in improving symptoms and lung function in childhood asthma has been shown in clinical trials, the effectiveness of these medications in real-world practice settings in reducing acute health care use has not been well-evaluated. This study examined the effect of inhaled antiinflammatory therapy on hospitalizations and emergency department (ED) visits by children for asthma.

DESIGN

Defined population cohort study over 1 year. Setting. Three managed care organizations (MCOs) in Seattle, Boston, and Chicago participating in the Pediatric Asthma Care-Patient Outcome Research and Treatment II trial. Participants. All 11 195 children, between 3 to 15 years old, with a diagnosis of asthma who were enrolled in the 3 MCOs between July 1996 and June 1997.

OUTCOME MEASURES

We identified children with 1 or more asthma diagnoses using automated encounter data. Medication dispensings were identified from automated pharmacy data. Multivariate logistic regression analysis was used to calculate effects of inhaled antiinflammatory therapy on the adjusted relative risk (RR) for hospitalization and ED visits for asthma.

RESULTS

Over 12 months, 217 (1.9%) of children had an asthma hospitalization, and 757 (6.8%) had an ED visit. After adjustment for age, gender, MCO, and reliever dispensing, compared with children who did not receive controllers, the adjusted RRs for an ED visit were: children with any (>/=1) dispensing of cromolyn, 0.4 (95% confidence interval [CI]: 0.3, 0.5); any inhaled corticosteroid (ICS), 0.5 (95% CI: 0.4, 0.6); any cromolyn or ICS combined (any controller), 0.4 (95% CI: 0.3, 0.5). For hospitalization, the adjusted RR for cromolyn was 0.6 (95% CI: 0.4, 0.9), for ICS 0.4 (95% CI: 0.3, 0.7), and for any controller 0.4 (95% CI: 0.3, 0.6). A significant protective effect for both events was seen among children with 1 to 5 and with >5 antiinflammatory dispensings. When the analysis was stratified by frequency of reliever dispensing, there was a significant protective effect for controllers on ED visits for children with 1 to 5 and with >5 reliever dispensings and on the risk of hospitalization for children with >5 reliever dispensings.

CONCLUSIONS

Inhaled antiinflammatory therapy is associated with a significant protective effect on the risk for hospitalization and ED visits in children with asthma. Cromolyn and ICSs were associated with similar effects on risks.asthma drug therapy, inhaled antiinflammatory agents, health maintenance organizations, hospitalization, emergency department.

Impact of the physician's participatory style in asthma outcomes and patient satisfaction

OBJECTIVES

To identify factors associated with asthma patients' perceptions of the propensity of pulmonologists to involve them in treatment decision-making, and its association with asthma outcomes.

DESIGN

Cross-sectional observational study performed from June 1995 to December 1997.

SETTING

Pulmonary unit of a university teaching hospital.

PATIENTS

Adult patients with asthma (n = 128).

MEASUREMENTS AND RESULTS

By patient self-report, mean physician's participatory decision-making (PDM) style score was 72 (maximum 100, 95% CI 65, 79). PDM scores were significantly correlated (P < .0001) with the duration of clinic visits (r = .63), patient satisfaction (r = .53), duration of tenure of doctor-patient relationship (r = .37), and formal education (r = .22, P = .023). Significantly higher PDM style scores were reported when visits lasted longer than 20 minutes and when a patient had a >6-month relationship with a particular doctor. PDM scores were also significantly correlated with possession of a written asthma action plan (r = .54, P < .0001), days affected by asthma (r = .36, P = .0001), asthma symptoms (r = .23, P = .017), and preferences for autonomy in asthma management decisions (r = .28, P = .0035). Those with PDM scores <50 reported significantly lower quality of life for all domains of a disease-specific instrument and the Short-Form 36 health survey version 1.0. In multiple regression analysis, PDM style was associated with the length of the office visit and the duration of tenure of the physician-patient relationship (R2 = 0.47, P = .0009). The adjusted odds ratio, per standard deviation decrease in PDM scores, for an asthma hospitalization was 2.0 (95% CI 1.2, 3.2) and for rehospitalization was 2.5 (95% CI 1.2, 4.2).

CONCLUSIONS

Patients' report of their physician's PDM style is significantly associated with health-related quality of life, work disability, and recent need for acute health services. Organizational factors, specifically longer visits and more time seeing a particular physician, are independently associated with more participatory visits. This has significant policy implications for asthma management.

Patient preferences for autonomy in decision making in asthma management

BACKGROUND

Lower patient preferences for autonomy in management decision making during asthma exacerbations have been associated with an increased risk for future hospital admissions. We sought to examine patient preferences for asthma self-management autonomy, and the clinical and psychosocial factors associated with autonomy preferences.

METHODS

A cross sectional observational study was performed with data collected between June 1995 and December 1997 of 212 adult patients with moderate to severe asthma managed, at least in part, at two teaching hospitals. Subjects completed a survey of autonomy preferences, quality of life, clinical morbidity and health service use, asthma knowledge, self-efficacy, coping styles, and psychosocial measures.

RESULTS

Patients preferred clinicians to assume the major role in most decision making about their management. However, patients wished to remain in control in choosing when to seek care and wanted to share decisions regarding initiating changes in medications during a moderate exacerbation. Multiple regression analysis showed that concerns about adverse effects of medications, education level, an active coping style, perceptions of the propensity of physicians to involve them in treatment decision making, and concerns about costs causing delays in seeking medical care were associated with preferences for autonomy in decision making. Autonomy preferences were not related to measures of concurrent clinical asthma control or health related quality of life.

CONCLUSIONS

In a group of patients with moderate to severe asthma, a high proportion of whom were from socioeconomically disadvantaged backgrounds, education level, perceived physician behaviour, cost barriers to care, and psychosocial factors (but not clinical asthma control or management) were related to patient preferences for autonomy in management decision making during asthma exacerbations. This has implications for asthma action plans and design of self-management programmes.

Rallicola deckeri n. sp. (Phthiraptera: Philopteridae) from Ruddy Woodcreepers Dendrocincla homochroa (Passeriformes: Furnariidae) collected in Campeche, Mexico

A new species of Rallicola Johnston and Harrison (Phthiraptera: Philopteridae) is described from lice collected from a series of Ruddy Woodcreepers Dendrocincla homochroa (Aves: Dendrocolaptinae) in Campeche, Mexico. Rallicola deckeri is easily recognized by the unique shape of the mesosome in the male and by the pattern of divided sternites on the female.

Transcranial Doppler (TCD) screening for stroke prevention in sickle cell anemia: pitfalls in technique variation

BACKGROUND

The Stroke Prevention Trial in Sickle Cell Anemia (STOP) identified children as being at high stroke risk if the time-averaged maximum mean velocity (TAMMV) of the middle cerebral or intracranial internal carotid arteries measured > or = 200 cm/s. These values were obtained utilizing a 2-mHz dedicated nonimaging pulsed Doppler technique (TCD) and manual measurements. Questions have been raised as to the comparability of results obtained with different ultrasound machines and measurement techniques.

OBJECTIVE

The purpose of this study was to compare nonimaging (TCD) and transcranial duplex imaging (TCDI) findings in children potentially at risk for stroke with sickle cell disease.

MATERIALS AND METHODS

Twenty-two children with sickle cell disease and no history of stroke were evaluated by both TCD and TCDI. Examinations were performed on the same day without knowledge of the other modality results and read independently using manually obtained measurements. Mean velocities, peak systolic velocities, and end diastolic velocities obtained by the two techniques were compared. In a subgroup, manual measurements were compared to electronically obtained measurements.

RESULTS

TCDI values were lower than TCD measurements for all vessels. TCDI TAMMV values were most similar to the TCD values in the middle cerebral artery (-9.0%) and distal internal cerebral artery (-10.8%), with greater variability in the anterior cerebral artery (-19.3%), bifurcation (-16.3%), and basilar arteries (-23.1%). Risk group placement based on middle cerebral artery TAMMV values did not change when comparing the two techniques. Measurements obtained electronically were lower than those obtained manually.

CONCLUSION

Velocities obtained by TCDI may be lower than TCD measurements, and these differences should be taken into consideration when performing screening for stroke risk and selection for prophylactic transfusion based on the STOP protocol.

Pigeon lice down under: taxonomy of Australian Campanulotes (Phthiraptera: Philopteridae), with a description of C. durdeni n. sp

Campanulotes flavus (Rudow, 1869) from Phaps chalcoptera is redescribed and illustrated. C. defectus Tendeiro, 1969, erroneously recorded from the extinct passenger pigeon Ectopistes migratorius, is shown to be a junior synonym of C. flavus, thus removing it from the list of lice thought to have gone extinct with the passenger pigeon. C. flavus elegans (Tendeiro, 1978) from P. elegans is elevated to specific rank and redescribed. Finally, C. durdeni n. sp. is described from its type host Ocyphaps lophotes.

Introduction to cognitive processes of expert pilots

This report addresses the historical problem that a very high percentage of accidents have been classified as involving "pilot error." Through extensive research since 1977, the Federal Aviation Administration determined that the predominant underlying cause of these types of accidents involved decisional problems or cognitive information processing. To attack these problems, Aeronautical Decision Making (ADM) training materials were developed and tested for ten years. Since the publication of the ADM training manuals in 1987, significant reductions in human performance error (HPE) accidents have been documented both in the U.S. and world wide. However, shortcomings have been observed in the use of these materials for recurrency training and in their relevance to more experienced pilots. The following discussion defines the differences between expert and novice decision makers from a cognitive information processing perspective, correlates the development of expert pilot cognitive processes with training and experience, and reviews accident scenarios which exemplify those processes. This introductory material is a necessary prerequisite to an understanding of how to formulate expert pilot decision making training innovations; and, to continue the record of improved safety through ADM training.

The predictive utility of the Teller acuity cards for assessing visual outcome in children with preterm birth and associated perinatal risks

We assessed binocular grating visual acuity with the Teller acuity cards (TAC) in 3-36-month-olds at risk for visual disorders. After 3-8 years, each child was assessed with the TAC and with a battery of tests of spatial and non-spatial vision. The initial TAC score: (1) was uncorrelated with any of the later measures; (2) had low positive, but high negative predictive value for the later tests; (3) had low sensitivity, but high specificity for identifying children with and without visual disorders, respectively. We concluded that early TAC grating acuity predicts visual outcome, but perhaps only for children with initially normal grating acuity.

Factors associated with hospital admissions and repeat emergency department visits for adults with asthma

BACKGROUND

A small proportion of patients with asthma account for a disproportionate number of acute health service events. To identify whether factors other than severity and low socioeconomic status were associated with this disproportionate use, a prospective study was undertaken to examine management and psychosocial factors associated with increased risk for admission to hospital with asthma and repeat visits to the emergency department over a 12 month period.

METHODS

A total of 293 patients with moderate or severe asthma managed at least in part at two teaching hospitals completed surveys of clinical status, acute events, sociodemographic, and psychological variables.

RESULTS

Twenty three percent had a single admission to hospital and 16% had two or more hospital admissions. Twenty six percent had one emergency department visit and 32% had two or more visits to the emergency department. In a multiple logistic regression model, adjusted for age, sex, education and income, odds ratios (95% CI) for baseline factors associated with hospital admissions over the next 12 months were: moderate severity compared with severe asthma 0.6 (0.2 to 0.9); no hospital admissions in the past 12 months 0.1 (0.01 to 0.2); not possessing a written asthma action plan 4.0 (1.5 to 10.7); less use of an avoidance coping style 0.4 (0.3 to 0.7); lower preferences for autonomy in asthma management decisions 1.4 (0.96 to 2.0). Adjusted odds ratios (95% CI) for repeat emergency department visits were: moderate asthma severity 0.3 (0.1 to 0.8); current regular use of oral corticosteroids 10.0 (3.1 to 32.4); a hospital admission in the past 12 months 2.9 (1.8 to 4.8); not possessing a written asthma action plan 2.2 (1.1 to 5.6); less dislike of asthma medications 0.7 (0.5 to 0.9).

CONCLUSIONS

In addition to factors relating to severity, not possessing a written asthma action plan, avoidance coping, and attitudes to self-management were related to acute use of health services in this at risk group. Interventions need to address or take these factors into account to reduce asthma morbidity.

Multicenter comparison of magnetic resonance imaging and transcranial Doppler ultrasonography in the evaluation of the central nervous system in children with sickle cell disease

PURPOSE

To compare the results of standardized magnetic resonance imaging (MRI) of the brain and transcranial Doppler (TCD) ultrasonography of cerebral arteries in school-aged children with sickle cell disease to determine the correlation between these two different neurodiagnostic tests.

PATIENTS AND METHODS

Data were analyzed from 78 children with sickle cell disease (mean age 11 yrs) who participated in both the Cooperative Study of Sickle Cell Disease (CSSCD) and the Stroke Prevention Trial in Sickle Cell Anemia (STOP). Patients who had experienced an overt stroke were excluded. MRI findings were classified as normal or "silent infarct." Results of TCD were classified as normal, conditional, or abnormal, based on the time-averaged maximum mean flow velocity in the proximal middle cerebral and distal internal carotid arteries.

RESULTS

Of 61 patients who had a normal MRI examination, 11 (18%) had either conditional (5 patients) or abnormal (6 patients) TCD results. Among 17 patients in whom silent infarction was seen on MRI, only 5 (29%) had a conditional (1 patient) or abnormal (4 patients) TCD velocity. Thus, discordant results were seen in 23 patients: 12 in which the TCD result was normal and the MRI abnormal; 11 in which the TCD velocity was elevated and the MRI normal.

CONCLUSIONS

Abnormal TCD and MRI examinations reveal different aspects of the pathophysiology of central nervous system (CNS) injury in sickle cell disease and are often discordant. Although TCD abnormality is predictive of overt stroke, the lack of concordance between TCD and MRI findings suggests a need to develop more sensitive and specific indicators of early CNS pathology, such as neuropsychometric testing and positron-emission tomography (PET) scans, and to obtain more information about microvascular pathologic processes that may affect CNS function.

Successful DNA immunization against measles: neutralizing antibody against either the hemagglutinin or fusion glycoprotein protects rhesus macaques without evidence of atypical measles

Measles remains a principal cause of worldwide mortality, in part because young infants cannot be immunized effectively. Development of new vaccines has been hindered by previous experience with a formalin-inactivated vaccine that predisposed to a severe form of disease (atypical measles). Here we have developed and tested potential DNA vaccines for immunogenicity, efficacy and safety in a rhesus macaque model of measles. DNA protected from challenge with wild-type measles virus. Protection correlated with levels of neutralizing antibody and not with cytotoxic T lymphocyte activity. There was no evidence in any group, including those receiving hemagglutinin-encoding DNA alone, of 'priming' for atypical measles.

Lessons from the Stroke Prevention Trial in Sickle Cell Anemia (STOP) study

Stroke is generally uncommon in children, but sickle cell disease is associated with a high risk of stroke in the early years of childhood. Large cerebral arteries, especially the middle cerebral and intracranial internal carotid, develop stenosis that predisposes to ischemic stroke. Noninvasive prediction of risk using transcranial Doppler ultrasonography made it possible to test primary stroke prevention in a clinical trial comparing chronic blood transfusion with standard care. A consortium of 14 clinical centers conducted a randomized clinical trial (Stroke Prevention in Sickle Cell Anemia--the "STOP" study) to test a strategy to prevent first stroke in children with sickle cell disease. Over 2000 children were screened with transcranial Doppler ultrasonography and of these, 130 with elevated blood velocity indicating high risk were enrolled in the trial. Regular red cell transfusions sufficient to reduce the percentage of Hb S gene product from over 90 to less than 30 of total hemoglobin was associated with a marked reduction in stroke. The untreated risk of 10% per year was reduced over 90% with treatment, an effect sufficient to cause early termination of the trial. Although treatment was unblinded, the design included blinded adjudication of possible stroke by a panel of neurologists remote from the study sites. The study led to a Clinical Alert, issued by the National Heart, Lung, and Blood Institute, recommending screening and consideration of treatment in children with sickle cell disease and 2 to 16 years of age who are at risk based on transcranial Doppler ultrasonography, and who have not had stroke.

Validity of a modified version of the Marks Asthma Quality of Life Questionnaire

To produce a scale useful for individual clinical decision making, the Marks Asthma Quality of Life Questionnaire (AQLQ-M) was modified to a 22-item scale using a 7-point Likert response scale, and the validity of the new instrument was assessed. Adult asthma subjects with moderate to severe disease, recruited from two hospitals in Adelaide, Australia, were surveyed at baseline (n = 293), and at 3-month follow-up (n = 234). Cronbach's alpha for the Total scale of the modified AQLQ-M (MAQLQ-M) was 0.97 and all subscale values exceeded 0.90. Test-retest reliability values for all scales were between 0.88 and 0.93. All correlations between disease reference measures were statistically significant to at least the p < 0.01 level. Stronger associations were seen with symptom and self-rating scales than for lung function, medication usage, and health service utilization measures of outcome. The MAQLQ-M showed good discriminative ability for all asthma symptom categories and for different FEV1 values. Moderate, statistically significant associations were seen between changes in MAQLQ-M scores and clinical measures. Higher baseline MAQLQ-M scores were associated with lower risks over 12 months for hospital admissions (odds ratio, OR = 0.58) and repeated emergency department visits (OR = 0.47). The MAQLQ-M is a highly valid measure of asthma-related quality of life.

Stroke prevention in sickle cell disease

Neurological complications, especially stroke, have long been recognized in sickle cell disease. Advances in care have increased the life expectancy of such patients, and recent information has better established the epidemiology of stroke. Prevention of stroke in children has been established in a clinical trial. Silent brain lesions revealed by MRI are common and are associated with impairments of cognitive function. Transfusion remains the primary mode of prevention and treatment for stroke, although interest is increasing in hydroxyurea; however, there are no data regarding its efficacy.

Retest variability of human infant contrast sensitivity: how many tests are sufficient?

Retest variability of a new infant contrast sensitivity (CS) card procedure was assessed by binocular measurement of a group of 20 6-month-olds twice within a 1-week period. Coefficient of reliability analyses showed that within-subject variability between tests was only slightly less than variation across subjects, which suggests that results from a single test are a poor predictor of an infant's "true" visual functioning. To determine how many tests are needed to estimate when infant CS stabilizes to within an acceptable (0.15 log unit) criterion, a second experiment was conducted in which a small group of subjects was tested repeatedly over a 2-week period. The results showed that averaging performance on 2 to 3 tests was required before an accurate estimate of the subject's performance could be obtained. Our results suggest that caution should be taken in the interpretation of a single measurement of infant visual functioning.

High viral load in the cerebrospinal fluid and brain correlates with severity of simian immunodeficiency virus encephalitis

AIDS dementia and encephalitis are complications of AIDS occurring most frequently in patients who are immunosuppressed. The simian immunodeficiency virus (SIV) model used in this study was designed to reproducibly induce AIDS in macaques in order to examine the effects of a neurovirulent virus in this context. Pigtailed macaques (Macaca nemestrina) were coinoculated with an immunosuppressive virus (SIV/DeltaB670) and a neurovirulent molecularly cloned virus (SIV/17E-Fr), and more than 90% of the animals developed moderate to severe encephalitis within 6 months of inoculation. Viral load in plasma and cerebrospinal fluid (CSF) was examined longitudinally to onset of AIDS, and viral load was measured in brain tissue at necropsy to examine the relationship of systemic and central nervous system (CNS) viral replication to the development of encephalitis. In all animals, plasma viral load peaked at 10 to 14 days postinfection and remained high throughout infection with no correlation found between plasma viremia and SIV encephalitis. In contrast, persistent high levels of CSF viral RNA after the acute phase of infection correlated with the development of encephalitis. Although high levels of viral RNA were found in the CSF of all macaques (six of six) during the acute phase, this high level was maintained only in macaques developing SIV encephalitis (five of six). Furthermore, the level of both viral RNA and antigen in the brain correlated with the severity of the CNS lesions. The single animal in this group that did not have CNS lesions had no detectable viral RNA in any of the regions of the brain. The results substantiate the use of CSF viral load measurements in the postacute phase of SIV infection as a marker for encephalitis and CNS viral replication.

Alterations in blood-brain barrier glucose transport in SIV-infected macaques

The neurological manifestations of HIV infection may be in part due to alterations in the blood-brain barrier. These may be caused by structural changes in the barrier or may consist of subtle metabolic or biochemical disturbances in barrier function. In the CNS, the family of glucose transporter proteins plays a key role in controlling movement of glucose across cell membranes. The 55 kDa isoform of glucose transporter 1 (GLUT1) regulates import of glucose from blood to brain across the endothelial cells of the blood-brain barrier (BBB), whereas the 45 kDa form of GLUT1 predominantly regulates nonvascular glial glucose uptake. In this study, expression of 55 and 45 kDa forms of GLUT1 in different regions of the brain from 18 SIV-infected macaques was measured by quantitative immunoblot and then compared with the severity of SIV encephalitis to determine whether neurologic disease is related to altered glucose metabolism at the BBB and in brain parenchyma. An inverse relationship was found between severity of SIV encephalitis and expression of the endothelial 55 kDa isoform of GLUT1 at the BBB in cortical grey matter, caudate nucleus, and cerebellum. A similar relationship also was found for the glial 45 kDa GLUT1 isoform in cortical grey matter. In addition, a significant increase in 55 kDa GLUT1 expression was found in caudate nucleus during the early stages of infection. In the brains of macaques with moderate to severe encephalitis, 55 kDa GLUT1 expression had declined to pre-infection levels. These GLUT1 alterations at the BBB and in glial cells may reflect severe disturbances in the CNS microenvironment that contribute to CNS dysfunction.

A South Australian population survey of the ownership of asthma action plans

OBJECTIVE

To examine the relationships between ownership of written asthma action plans, asthma morbidity, use of devices, and patients' perceptions of their asthma management.

DESIGN AND SETTING

A random population survey (in 1996) of the South Australian population aged 15 years or over, using interviewers to administer a questionnaire.

PARTICIPANTS

People who reported that they had current, doctor-diagnosed asthma.

MAIN OUTCOME MEASURES

Prevalence of written asthma action plans; night-time awakenings from asthma; ownership of peak flow meters; and people's perceptions of their asthma management.

RESULTS

The ownership of asthma action plans by people with self-reported asthma was 33% and has declined since 1995 (42%; P < 0.001). Fifteen per cent were awakened weekly or more frequently by asthma symptoms. These people were more likely to have a peak flow meter and a written action plan, but less likely to consider they had been provided with enough information about their asthma, to feel comfortable managing their asthma, or to find it easy to see their doctor. Having a written asthma action plan was associated with regular corticosteroid use, understanding asthma, having enough information and owning a peak flow meter.

CONCLUSIONS

Ownership of asthma action plans in South Australia is suboptimal. Before we develop new strategies to improve asthma outcomes, we must determine whether there is a need to target people with less severe asthma and/or improve the use of guidelines by health professionals.

Measles virus infection in rhesus macaques: altered immune responses and comparison of the virulence of six different virus strains

Measles remains a major cause of childhood mortality, with questions about virus virulence and pathogenesis still requiring answers. Rhesus macaques were infected with 5 different culture-adapted strains of measles virus, including 2 from patients with progressive vaccine-induced disease, and a sixth nonculture-adapted strain, Bilthoven. All caused infection detectable by reverse transcriptase-polymerase chain reaction and induction of antibody. Chicago-1 and Bilthoven induced viremias detectable by leukocyte cocultivation. Bilthoven induced Koplik's spots, conjunctivitis, and rash. Lymphopenia and depressed interleukin (IL)-2 production were followed by monocytosis and eosinophilia. All monkeys, including 41 involved in a primate facility outbreak, showed suppressed responses to phytohemagglutinin. As the rash resolved production of IL-2, IL-1beta, tumor necrosis factor-alpha, IL-6, and IL-5 mRNA increased. Monkeys are useful for studies of measles immunopathogenesis, but virus strains must be carefully chosen. Increased virulence of vaccine strains isolated from immunocompromised infants with fatal infections was not evident.

Sterilization and disinfection in general practice in Northern Ireland

In view of the recent trend towards more minor surgery being carried out in general practice we decided to conduct a postal survey to assess the level of knowledge of sterilization and disinfection and the use of benchtop sterilizers in general practice in Northern Ireland. The survey, of all 366 practices in the Province, was carried out in January/March 1998. One hundred and eleven (30%) completed questionnaires were returned. All practices performed at least one of a range of procedures requiring sterilization or disinfection, e.g., minor surgery 95%, cervical smear taking 98%, syringing of ears 98%. Only 76% of practices had a benchtop sterilizer and 39% did not have access to a sterile supply department (SSD); 32% of the latter had no desire to utilize such a service. Only 25% and 34% correctly identified the Medical Devices Agency (MDA) definitions of sterilization and disinfection respectively. The MDA Device Bulletin on benchtop sterilizers had been read by only 26% of respondents. There was an 86% interest in attending a workshop on sterilization and disinfection. The concepts and practice of sterilization and disinfection appear not to be clearly understood. We conclude that resources must be identified to provide appropriate education in this important area for primary care staff.

Production of atypical measles in rhesus macaques: evidence for disease mediated by immune complex formation and eosinophils in the presence of fusion-inhibiting antibody

The severe disease atypical measles occurred when individuals immunized with a poorly protective inactivated vaccine contracted measles, and was postulated to be due to a lack of fusion-inhibiting antibodies. Here, rhesus macaques immunized with formalin-inactivated measles vaccine developed transient neutralizing and fusion-inhibiting antibodies, but no cytotoxic T-cell response. Subsequent infection with measles virus caused an atypical rash and pneumonitis, accompanied by immune complex deposition and an increase in eosinophils. Fusion-inhibiting antibody appeared earlier in these monkeys than in non-immunized monkeys. These data indicate that atypical measles results from previous priming for a nonprotective type 2 CD4 T-cell response rather than from lack of functional antibody against the fusion protein.

Pathogenesis of simian immunodeficiency virus pneumonia: an immunopathological response to virus

Although many human immunodeficiency virus-infected individuals develop lymphocytic interstitial pneumonia, the roles of host and viral factors in the pathogenesis of pneumonia are not well defined. Human immunodeficiency virus-infected children with lymphocytic interstitial pneumonia have human immunodeficiency virus-specific cytotoxic T cells in pulmonary infiltrates, increased survival time, and a reduced incidence of opportunistic infections, suggesting that lymphocytic interstitial pneumonia may reflect an effective antiviral immune response. In this study, 20 macaques were inoculated with related macrophage-tropic simian immunodeficiency viruses and examined for pulmonary lesions and virus gene expression. Ten macaques developed moderate to severe pneumonia characterized by perivascular, peribronchial, and interstitial infiltrates of lymphocytes and macrophages. Large numbers of pulmonary cytotoxic lymphocytes were demonstrated in macaques with moderate to severe pneumonia (P < 0.05) by immunostaining for TIA-1. There was no difference in viral load between macaques with moderate to severe pneumonia and those with mild to no pulmonary lesions. In five macaques inoculated with the same virus swarm, there was a significant (P < 0.05) inverse correlation between the percentage decline in CD4+ T-cell counts and the severity of pulmonary lesions. Pulmonary infiltrates of cytotoxic lymphocytes, the lack of correlation between severity of pulmonary lesions and virus gene expression, and the inverse relationship between pneumonia and inmune status suggest that simian immunodeficiency virus pneumonia may represent an immunopathological response to macrophage-tropic virus.

Measuring individual differences in change with multidimensional Rasch models

Item response models have been developed to explore change measurement, including those proposed by Fischer and his colleagues (e.g., Fischer & Pazer, 1991; Fischer & Ponocny, 1994), Andersen (1985) and Embretson (1991). In this article, we propose another multidimensional Rasch model, the multidimensional random coefficient multinomial logit (MRCML) model (Adams, Wilson, & Wang, 1997). All these models are briefly reviewed and compared. The MRCML can be applied to not only polytomous items but also investigation of variations in item difficulties. Based on variations in difficulties across occasions and items, five kinds of models are proposed. Some simulation studies were conducted to examine parameter recovery of the MRCML model under various testing situations. All the parameters were recovered very well. A real data set was analyzed to show applications of the MRCML to measuring individual differences in change.

A modified card procedure for measuring human infant color vision

To improve test efficiency, we modified our previously introduced contrast/color card test by including a patterned test stimulus and reducing the number of stimuli in both experimental phases. Compared with the prototype, completion rate improved substantially (79 vs. 37%) but test time decreased only modestly (19 vs. 21 min). Achromatic contrast discrimination improved threefold (mean, 0.06 vs. 0.20 log units), but the percentage of 2-month-old infants who discriminated (from gray) 660-nm red (86 vs. 80%) and 580-nm yellow (52 vs. 55%) was consistent. In addition, 48% discriminated 574-nm yellow-green. Moreover, because 88% of infants' failures included the respective adult brightness/luminance match, a small range of relative luminances is adequate for testing infant color vision.

Prevention of a first stroke by transfusions in children with sickle cell anemia and abnormal results on transcranial Doppler ultrasonography

BACKGROUND

Blood transfusions prevent recurrent stroke in children with sickle cell anemia, but the value of transfusions in preventing a first stroke is unknown. We used transcranial Doppler ultrasonography to identify children with sickle cell anemia who were at high risk for stroke and then randomly assigned them to receive standard care or transfusions to prevent a first stroke.

METHODS

To enter the study, children with sickle cell anemia and no history of stroke had to have undergone two transcranial Doppler studies that showed that the time-averaged mean blood-flow velocity in the internal carotid or middle cerebral artery was 200 cm per second or higher. The patients were randomly assigned to receive standard care or transfusions to reduce the hemoglobin S concentration to less than 30 percent of the total hemoglobin concentration. The incidence of stroke (cerebral infarction or intracranial hemorrhage) was compared between the two groups.

RESULTS

A total of 130 children (mean [+/-SD] age, 8.3+/-3.3 years) were enrolled; 63 were randomly assigned to receive transfusions and 67 to receive standard care. At base line, the transfusion group had a slightly lower mean hemoglobin concentration (7.2 vs. 7.6 g per deciliter, P=0.001) and hematocrit (20.4 vs. 21.7 percent, P=0.002). Ten patients dropped out of the transfusion group, and two patients crossed over from the standard-care group to the transfusion group. There were 10 cerebral infarctions and 1 intracerebral hematoma in the standard-care group, as compared with 1 infarction in the transfusion group -- a 92 percent difference in the risk of stroke (P<0.001). This result led to the early termination of the trial.

CONCLUSIONS

Transfusion greatly reduces the risk of a first stroke in children with sickle cell anemia who have abnormal results on transcranial Doppler ultrasonography.

Oriented cell divisions and cellular morphogenesis in the zebrafish gastrula and neurula: a time-lapse analysis

We have taken advantage of the optical transparency of zebrafish embryos to investigate the patterns of cell division, movement and shape during early stages of development of the central nervous system. The surface-most epiblast cells of gastrula and neurula stage embryos were imaged and analysed using a computer-based, time-lapse acquisition system attached to a differential interference contrast (DIC) microscope. We find that the onset of gastrulation is accompanied by major changes in cell behaviour. Cells collect into a cohesive sheet, apparently losing independent motility and integrating their behaviour to move coherently over the yolk in a direction that is the result of two influences: towards the vegetal pole in the movements of epiboly and towards the dorsal midline in convergent movements that strengthen throughout gastrulation. Coincidentally, the plane of cell division becomes aligned to the surface plane of the embryo and oriented in the anterior-posterior (AP) direction. These behaviours begin at the blastoderm margin and propagate in a gradient towards the animal pole. Later in gastrulation, cells undergo increasingly mediolateral-directed elongation and autonomous convergence movements towards the dorsal midline leading to an enormous extension of the neural axis. Around the equator and along the dorsal midline of the gastrula, persistent AP orientation of divisions suggests that a common mechanism may be involved but that neither oriented cell movements nor shape can account for this alignment. When the neural plate begins to differentiate, there is a gradual transition in the direction of cell division from AP to the mediolateral circumference (ML). ML divisions occur in both the ventral epidermis and dorsal neural plate. In the neural plate, ML becomes the predominant orientation of division during neural keel and nerve rod stages and, from late neural keel stage, divisions are concentrated at the dorsal midline and generate bilateral progeny (C. Papan and J. A. Campos-Ortega (1994) Roux's Arch. Dev. Biol. 203, 178–186). Coincidentally, cells on the ventral surface also orient their divisions in the ML direction, cleaving perpendicular to the direction in which they are elongated. The ML alignment of epidermal divisions is well correlated with cell shape but ML divisions within the neuroepithelium appear to be better correlated with changes in tissue morphology associated with neurulation.

The evolving role of transcranial doppler in stroke prevention and treatment

Without focusing on established indications for transcranial Doppler (TCD) such as monitoring vasospasm after subarachnoid hemorrhage and detecting intracranial stenosis (sickle cell disease, stroke, etc.), we describe the role of TCD in carotid endarterectomy (CEA) and angioplasty, acute ischemic stroke, as well as competence and the practice of TCD. In addition to duplex ultrasound and angiography TCD can be used to select patients for CEA because it detects hemodynamically significant extracranial stenosis and tandem intracranial stenoses, and identifies asymptomatic patients at potentially high risk of stroke because of exhausted vasomotor reactivity or brain microembolization. TCD identifies in real time brain hypoperfusion, embolism, and hyperperfusion and thus may be helpful in reducing cerebrovascular complications of CEA/angioplasty. In acute ischemic stroke, TCD can reliably identify the patency of middle cerebral and basilar arteries, high resistance flow patterns due to increased intracranial pressure, and progression to cerebral circulatory arrest. TCD also can monitor spontaneous or induced arterial recanalization. Limitations include operator and interpreter dependency, absent temporal "windows" leading to unsuccessful insonation in 10% to 15% of patients older than 60 years, as well as difficulties with probe positioning and fixation for monitoring. However, the use of ultrasound contrast agents and improved probe fixation devices help avoid these factors. The key to the successful practice of TCD is training of technical personnel and education of the interpreting and referring physicians as to when to use TCD and what to expect from it. The advantages of TCD should be given particular consideration: portability, repeatability, long-term monitoring, emboli detection, and inexpensiveness. TCD machines and transducers need to be tuned to the target disorders; that is, larger sample volume, higher power, and so forth, and TCD technology should be implemented in phases I to II as well as in phase III trials of preventive interventions and stroke therapies.

Medical and neurological complications of ischemic stroke: experience from the RANTTAS trial. RANTTAS Investigators

BACKGROUND AND PURPOSE

Medical and neurological complications after acute ischemic stroke may adversely impact outcome and in some cases may be preventable. Limited data exist regarding the frequency of such complications occurring in the first days after the ictus and the relationship of these complications to outcome. Our objective was to identify the types, severity, and frequency of medical and neurological complications following acute ischemic stroke and to determine their role in mortality and functional outcome.

METHODS

Rates of serious (life-threatening) and nonserious medical and neurological complications and mortality were derived from the placebo limb of the Randomized Trial of Tirilazad Mesylate in Acute Stroke (RANTTAS) database (n=279). Complications were correlated with clinical outcome using logistic regression techniques.

RESULTS

Of all patients, 95% had at least one complication. The most common serious medical complication was pneumonia (5%), and the most common serious neurological complication was new cerebral infarction or extension of the admission infarction (5%). The 3-month mortality was 14%; 51% of these deaths were attributed primarily to medical complications. Outcome was significantly worse in patients with serious medical complications, after adjustment for baseline imbalances, as measured by the Barthel Index (odds ratio [OR], 6.1; 95% confidence interval [CI], 2.5 to 15.1) and by the Glasgow Outcome Scale (OR, 11.6; 95% CI, 4.3 to 30.9). After death was discounted, serious medical complications were associated with severe disability at 3 months as determined by the Glasgow Outcome Scale (OR, 4.4; 95% CI, 1.3 to 14.8).

CONCLUSIONS

Medical complications that follow ischemic stroke not only influence mortality but may influence functional outcome.

Stroke prevention trial in sickle cell anemia

Stroke occurs in 7-8% of children with Sickle Cell Disease (Hb SS) and is a major cause of morbidity. Rates of recurrence have been reduced from 46-90% to less than 10% through chronic blood transfusions. Prevention of first stroke, however, would be preferable because even one stroke can cause irreversible brain injury. Transcranial Doppler (TCD) ultrasound can detect arterial blood flow rates associated with subsequent stroke risk. By combining TCD screening and a potentially effective treatment, first stroke may be prevented. The Stroke Prevention Trial in Sickle Cell Anemia (STOP) is the first stroke prevention trial in Hb SS and the first randomized, controlled use of transfusion in Hb SS. This multi-center trial is designed to test whether reducing sickle hemoglobin to 30% or less with periodic blood transfusions will reduce first-time stroke by at least 70% compared to standard care. Primary endpoints will be clinically evident symptoms of cerebral infarction with consistent findings on Magnetic Resonance Imaging and Angiography (MRI/MRA) or symptomatic intracranial hemorrhage. Secondary endpoints will be asymptomatic brain lesions detected by MRI in brain areas not involved in primary endpoints. The design calls for a 6-month start-up interval, 18 months of TCD screening and randomization, and observation for stroke from entry through month 54. Key features of the trial are standardized TCD and MRI/MRA protocols interpreted blindly, and blinded adjudication of endpoints. The sample size (60 per treatment group) is based on prospective data relating TCD velocity to risk of stroke. A time-averaged mean velocity of > or = 200 cm/sec is associated with a 46% risk of cerebral infarction over 39 months. The sample size is sufficient to detect 70% reduction in the primary endpoint at 90% power. This trial will determine if transfusion is effective in the primary prevention of stroke. Secondary aims may further the understanding of the effects of transfusion on the brain and guide future research into cerebrovascular disease in Hb SS.

Human newborn color vision: measurement with chromatic stimuli varying in excitation purity

Groups of newborn human infants (N = 180) were habituated to large 16 degrees achromatic ("white") lights of varying luminance (0.35 to 1.16 log cd/m2) and then tested for recovery of habituation to 16 degrees green (dominant lambda = 545 nm), yellow (dominant lambda = 585 nm) or red (dominant lambda = 650 nm) lights which varied in the level of excitation purity (range = 32 to 83%). Results showed that newborns discriminated the chromatic stimuli from white only when excitation purity values exceeded at least 41% for 545-nm green, 47% for 650-nm red, and 65% for 585-nm yellow, limits much higher than those for adults (<1%). Taken together with the results from previous experiments, these saturation discrimination data (with the exception of the yellow data), provide some support for an expanded MacAdam ellipse model of early color discrimination (Brown, 1993; Teller & Lindsey, 1993). This helps reinforce the current view that neonates' vision is based on general rather than selective immaturities or inefficiencies within the requisite optical, photoreceptoral and neural mechanisms.

Pathogenesis of ovine lentiviral encephalitis: derivation of a neurovirulent strain by in vivo passage

The lentiviruses of sheep replicate almost exclusively in macrophages and cause chronic interstitial pneumonia, arthritis, and mastitis, but only rarely encephalitis. This study was undertaken to determine whether a non-neurovirulent field strain of ovine lentivirus isolated from joint fluid that replicated productively in lung and joint macrophages could be adapted to enter and replicate in the brain and cause encephalitis. The field isolate was passed seven times sequentially by intracerebral inoculation of sheep. The neuroadapted strain of virus caused severe encephalitis typical of visna in four of four sheep inoculated intracerebrally. The virus replicated to high titers in the brains of these animals and in cultured microglia. The inflammatory response in the brain was characterized by intense infiltrates of macrophages and CD8+ and CD4+ T cells. Many of the perivascular macrophages demonstrated TNF-alpha expression and there was upregulation of MHC Class II antigen expression on both inflammatory cells and endothelium. Inoculation of this neuroadapted virus into the bone marrow of three animals resulted in persistent infection and cell-associated viremia, but not encephalitis. Virus was not detected in brains from these animals, indicating that the virus was not neuroinvasive. These data suggest that neuroinvasiveness and neurovirulence are separate pathogenic determinants, both of which are required for the development of encephalitis during natural infection.

Long-term stroke risk in children with sickle cell disease screened with transcranial Doppler

Stroke is an important complication of sickle cell disease. Stroke prediction is clinically important because it offers the possibility of primary prevention. In 1992, transcranial Doppler (TCD) evidence of elevated intracranial internal carotid or middle cerebral artery velocity was demonstrated to be associated strongly with an increased risk of ischemic stroke. This study extends the original study and includes 125 more children, longer follow-up, and intracranial hemorrhage in the stroke-risk model. Elevated time averaged mean maximum blood flow velocity, especially when velocity is 200 cm/sec or greater by TCD, was associated strongly with stroke risk. The cases not predicted by TCD point to the need for more information on the optimal timing of TCD surveillance for stroke risk.

Internal carotid artery occlusion in a child with sickle cell disease: case report and immunohistochemical study

PURPOSE

The purpose of this report is to describe the clinical and pathologic features of a patient with acute thrombosis of both internal carotid arteries leading to death.

METHODS

This is a case report of special interest because of extensive brain vessel pathologic examination.

RESULTS

The analysis of this case showed that the brain had suffered massive infarction and cerebral edema. The internal carotid arteries (ICAs) were occluded by acute thrombus. The arterial wall of the left ICA, studied at its distal segment, showed a small amount of intimal hyperplasia which did not cause encroachment on the lumen. Immunohistochemical stains indicated that this lesion was formed by proliferative vascular smooth muscle rather than incremental thrombus formation.

CONCLUSION

Acute thrombus formation can occur in the large cerebral arteries of children with sickle cell disease in the presence of only minimal intimal hyperplasia. The intimal hyperplasia which forms the sickle related vasculopathy seen on angiography or detected by Transcranial Doppler may be more related to stimulation of smooth muscle cells than dysregulation of thromboregulation at the endothelial surface. Implications for preventive treatment are discussed.

Contrast sensitivity in infants and children with Down syndrome

A new contrast sensitivity (CS) card test was used to estimate contrast sensitivity in 18 infants and children with Down syndrome (DS). The results showed that although the overall shape of the contrast sensitivity functions (CSFs) of the subjects with DS was the typical inverted-U, their CSFs were depressed in comparison to control subjects and this relative loss became larger with increasing spatial frequency. In addition, there was little improvement in CS with age and the mean CSF among children with DS (mean age = 7.3 years) was equivalent statistically to a group of 12-month-olds without DS. The Teller Acuity Cards (TAC) were also used to assess visual acuity in 17 of the 18 children in our sample. The results of these tests showed that their visual acuity (VA) was significantly lower than normal, but was consistent with that extrapolated from each subject's CSF. Taken together with previous anatomical and developmental findings, our results suggest that the deficits in spatial vision among children with DS is due primarily to restricted cortical development, and secondarily, to the additional accommodative and ocular conditions that are prevalent in this population.