The Practice of Paediatric Radiation Oncology in Low- and Middle-income Countries: Outcomes of an International Atomic Energy Agency Study

AIMS

Childhood cancer survival is suboptimal in most low- and middle-income countries (LMICs). Radiotherapy plays a significant role in the standard care of many patients. To assess the current status of paediatric radiotherapy, the International Atomic Energy Agency (IAEA) undertook a global survey and a review of practice in eight leading treatment centres in middle-income countries (MICs) under Coordinated Research Project E3.30.31; 'Paediatric radiation oncology practice in low and middle income countries: a patterns-of-care study by the International Atomic Energy Agency.'

MATERIALS AND METHODS

A survey of paediatric radiotherapy practices was distributed to 189 centres worldwide. Eight leading radiotherapy centres in MICs treating a significant number of children were selected and developed a database of individual patients treated in their centres comprising 46 variables related to radiotherapy technique.

RESULTS

Data were received from 134 radiotherapy centres in 42 countries. The percentage of children treated with curative intent fell sequentially from high-income countries (HICs; 82%) to low-income countries (53%). Increasing deficiencies were identified in diagnostic imaging, radiation staff numbers, radiotherapy technology and supportive care. More than 92.3% of centres in HICs practice multidisciplinary tumour board decision making, whereas only 65.5% of centres in LMICs use this process. Clinical guidelines were used in most centres. Practice in the eight specialist centres in MICs approximated more closely to that in HICs, but only 52% of patients were treated according to national/international protocols whereas institution-based protocols were used in 41%.

CONCLUSIONS

Quality levels in paediatric radiotherapy differ among countries but also between centres within countries. In many LMICs, resources are scarce, coordination with paediatric oncology is poor or non-existent and access to supportive care is limited. Multidisciplinary treatment planning enhances care and development may represent an area where external partners can help. Commitment to the use of protocols is evident, but current international guidelines may lack relevance; the development of resources that reflect the capacity and needs of LMICs is required. In some LMICs, there are already leading centres experienced in paediatric radiotherapy where patient care approximates to that in HICs. These centres have the potential to drive improvements in service, training, mentorship and research in their regions and ultimately to improve the care and outcomes for paediatric cancer patients.

Infection-related complications during treatment for childhood acute lymphoblastic leukemia

Background

Comprehensive studies on neutropenia and infection-related complications in patients with acute lymphoblastic leukemia (ALL) are lacking.

Patients and methods

We evaluated infection-related complications that were grade ≥3 on National Cancer Institute's Common Terminology Criteria for Adverse Events (version 3.0) and their risk factors in 409 children with newly diagnosed ALL throughout the treatment period.

Results

Of the 2420 infection episodes, febrile neutropenia and clinically or microbiologically documented infection were seen in 1107 and 1313 episodes, respectively. Among documented infection episodes, upper respiratory tract was the most common site (n = 389), followed by ear (n = 151), bloodstream (n = 147), and gastrointestinal tract (n = 145) infections. These episodes were more common during intensified therapy phases such as remission induction and reinduction, but respiratory and ear infections, presumably viral in origin, also occurred during continuation phases. The 3-year cumulative incidence of infection-related death was low (1.0±0.9%, n = 4), including 2 from Bacillus cereus bacteremia. There was no fungal infection-related mortality. Age 1-9.9 years at diagnosis was associated with febrile neutropenia (P = 0.002) during induction and febrile neutropenia and documented infection (both P < 0.001) during later continuation. White race was associated with documented infection (P = 0.034) during induction. Compared with low-risk patients, standard- and high-risk patients received more intensive therapy during early continuation and had higher incidences of febrile neutropenia (P < 0.001) and documented infections (P = 0.043). Furthermore, poor neutrophil surge after dexamethasone pulses during continuation, which can reflect the poor bone marrow reserve, was associated with infections (P < 0.001).

Conclusions

The incidence of infection-related death was low. However, young age, white race, intensive chemotherapy, and lack of neutrophil surge after dexamethasone treatment were associated with infection-related complications. Close monitoring for prompt administration of antibiotics and modification of chemotherapy should be considered in these patients.

Treatment of childhood acute lymphoblastic leukemia in central America: a lower-middle income countries experience

BACKGROUND

Five Asociación de Hemato-Oncología de Centroamérica (AHOPCA) countries have used an adapted BFM-based protocol for childhood acute lymphoblastic leukemia (ALL).

PROCEDURE

In the AHOPCA-ALL 2008 protocol, patients were stratified by age, white blood cell count, immunophenotype, central nervous system involvement, day 8 prednisone response, and morphologic bone marrow response to induction therapy. Patients at Standard Risk (SR) received a three-drug induction regimen, a reinduction phase, and maintenance with protracted intrathecal therapy. Those at Intermediate (IR) and High Risk (HR) received, in addition, daunorubicin during induction therapy, a consolidation phase and two or three reinduction phases respectively.

RESULTS

From August 2008 through July 2012, 1,313 patients were enrolled: 353 in SR, 548 in IR, 412 in HR. During induction therapy, 3.0% of patients died, 2.7% abandoned treatment, 1.1% had resistant ALL, and 93.2% achieved morphological complete remission (CR). Deaths and abandonment in first CR occurred in 2.7% and in 7.0% of patients, respectively. The relapse rate at a median observation time of 2.1 years was 15.0%. At 3 years, the event-free survival (EFS) and overall survival (OS), with abandonment considered as an event, were 59.4% (SE 1.7) and 68.2% (SE 1.6). Three-year EFS was 68.5% (SE 3.0), 62.1% (SE 2.6), and 47.8% (SE 3.2) for SR, IR, and HR groups. Adolescents had a significantly higher relapse rate (P = 0.001).

CONCLUSIONS

This experience shows that common international studies are feasible in lower-middle income countries. Toxic deaths, abandonment of treatment, and relapses remain major obstacles to the successful treatment. Alternative treatment strategies may be beneficial.

A revised definition for cure of childhood acute lymphoblastic leukemia

With improved contemporary therapy, we re-assess long-term outcome in patients completing treatment for childhood acute lymphoblastic leukemia to determine when cure can be declared with a high degree of confidence. In 6 successive clinical trials between 1984 and 2007, 1291(84.5%) patients completed all therapy in continuous complete remission. The post-therapy cumulative risk of relapse or development of a second neoplasm and the event-free survival rate and overall survival were analyzed according to the presenting features and the three treatment periods defined by relative outcome. Over the three treatment periods, there has been progressive increase in the rate of event-free survival (65.2% vs. 74.8% vs. 85.1% [P<0.001]) and overall survival (76.5% vs. 81.1% vs. 91.7% [P<0.001]) at 10 years. The most important predictor of outcome after completion of therapy was the type of treatment. In the most recent treatment period, which omitted the use of prophylactic cranial irradiation, the post-treatment cumulative risk of relapse was 6.4%, death in remission 1.5%, and development of a second neoplasm 2.3% at 10 years, with all relapses except one occurring within 4 years off therapy. None of the 106 patients with the t(9;22)/BCR-ABL1, t(1;19)/TCF3-PBX1 or t(4;11)/MLL-AFF1 had relapsed after 2 years from completion of therapy. These findings demonstrate that with contemporary effective therapy that excludes cranial irradiation, approximately 6% of children with acute lymphoblastic leukemia may relapse after completion of treatment, and those who remain in remission at 4 years post-treatment may be considered cured (i.e., less than 1 % chance of relapse).

ETV6-RUNX1-positive childhood acute lymphoblastic leukemia: improved outcome with contemporary therapy

ETV6-RUNX1 fusion is the most common genetic aberration in childhood acute lymphoblastic leukemia (ALL). To evaluate whether outcomes for this drug-sensitive leukemia are improved by contemporary risk-directed therapy, we studied clinical features, response and adverse events of 168 children with newly diagnosed ETV6-RUNX1-positive ALL on St Jude Total Therapy studies XIIIA (N=36), XIIIB (N=38) and XV (N=94). Results were compared with 494 ETV6-RUNX1-negative B-precursor ALL patients. ETV6-RUNX1 was associated with age 1-9 years, pre-treatment classification as low risk and lower levels of minimal residual disease (MRD) on day 19 of therapy (P<0.001). Event-free survival (EFS) or overall survival (OS) did not differ between patients with or without ETV6-RUNX1 in Total XIIIA or XIIIB. By contrast, in Total XV, patients with ETV6-RUNX1 had significantly better EFS (P=0.04; 5-year estimate, 96.8±2.4% versus 88.3±2.5%) and OS (P=0.04; 98.9±1.4% versus 93.7±1.8%) than those without ETV6-RUNX1. Within the ETV6-RUNX1 group, the only significant prognostic factor associated with higher OS was the treatment protocol Total XV (versus XIIIA or XIIIB) (P=0.01). Thus, the MRD-guided treatment schema including intensive asparaginase and high-dose methotrexate in the Total XV study produced significantly better outcomes than previous regimens and demonstrated that nearly all children with ETV6-RUNX1 ALL can be cured.

Efficacy of high-dose methotrexate, ifosfamide, etoposide and dexamethasone salvage therapy for recurrent or refractory childhood malignant lymphoma

BACKGROUND

Children with recurrent or refractory malignant lymphoma generally have a poor prognosis. There is a need for new active drug combinations for this high-risk group of patients.

PATIENTS AND METHODS

This study evaluated the activity and toxicity of the methotrexate, ifosfamide, etoposide and dexamethasone (MIED) regimen for childhood refractory/recurrent non-Hodgkin's lymphoma (NHL) or Hodgkin's lymphoma (HL). From 1991 through 2006, 62 children with refractory/recurrent NHL (n = 24) or HL (n = 38) received one to six cycles of MIED. Based on MIED response, intensification with hematopoietic stem cell transplantation (HSCT) was considered.

RESULTS

There were 10 complete (CR) and 5 partial responses (PR) among the 24 children with NHL [combined response rate, 63%; 95% confidence interval (CI) 38% to 73%]. There were 13 CR and 18 PR among the 37 assessable children with HL (combined response rate, 84%; 95% CI, 68% to 94%). Although 59% courses were associated with grade IV neutropenia, treatment was well tolerated and without toxic deaths.

CONCLUSIONS

MIED is an effective regimen for refractory/recurrent childhood malignant lymphoma, permitting a bridge to intensification therapy with HSCT.

Long-term results of St Jude Total Therapy Studies 11, 12, 13A, 13B, and 14 for childhood acute lymphoblastic leukemia

We analyzed the long-term outcome of 1011 patients treated in five successive clinical trials (Total Therapy Studies 11, 12, 13A, 13B, and 14) between 1984 and 1999. The event-free survival improved significantly (P=0.003) from the first two trials conducted in the 1980s to the three more recent trials conducted in the 1990s. Approximately 75% of patients treated in the 1980s and 80% in the 1990s were cured. Early intensive triple intrathecal therapy, together with more effective systemic therapy, including consolidation and reinduction treatment (Studies 13A and 13B) as well as dexamethasone (Study 13B), resulted in a very low rate of isolated central nervous system (CNS) relapse rate (<2%), despite the reduced use of cranial irradiation. Factors consistently associated with treatment outcome were age, leukocyte count, immunophenotype, DNA index, and minimal residual disease level after remission induction treatment. Owing to concerns about therapy-related secondary myeloid leukemia and brain tumors, in our current trials we reserve the use of etoposide for patients with refractory or relapsed leukemia undergoing hematopoietic stem cell transplantation, and cranial irradiation for those with CNS relapse. The next main challenge is to further increase cure rates while improving quality of life for all patients.

Incidence and predictors of treatment-related mortality in paediatric acute leukaemia in El Salvador

Survival rates among children with leukaemia in low-income countries are lower than those in high-income countries. This has been attributed in part to higher treatment-related mortality (TRM). We examined the demographics, treatment, and outcomes of paediatric patients in El Salvador with acute lymphoblastic leukaemia (ALL) or acute myeloid leukaemia (AML) to determine the incidence, causes, and risk factors for TRM. Two trained data managers collected data prospectively; no patients were excluded. Biological, socioeconomic and nutritional predictors were examined. A total of 469 patients with ALL and 78 patients with AML were included. The 2-year cumulative incidence of TRM was significantly higher among children with AML (35.4±6.4%) than those with ALL (12.5±1.7%; P<0.0001). However, the proportion of deaths attributable to the toxicity of treatment did not differ significantly between AML (25/47, 53.2%) and ALL (55/107, 51.4%; P=0.98). Among children with ALL, low monthly income (P=0.04) and low parental education (P=0.02) significantly increased the risk of TRM. Among children with AML, biological, socioeconomic, and nutritional variables were not associated with TRM. In this low-income country, toxic death significantly contributes to mortality in both ALL and AML. A better understanding of the effect of socioeconomic status on TRM may suggest specific strategies for patients with ALL.

Increased risk for CNS relapse in pre-B cell leukemia with the t(1;19)/TCF3-PBX1

To evaluate the impact of contemporary therapy on the clinical outcome of children with pre-B acute lymphoblastic leukemia (ALL) and the t(1;19)/TCF3/PBX1, we analyzed 735 patients with B-cell precursor ALL treated in four successive protocols at St Jude Children's Research Hospital. The 41 patients with the t(1;19) had a comparable event-free survival to that of the 694 patients with other B-cell precursor ALL (P=0.63; 84.2+/-7.1% (s.e.) vs 84.0+/-1.8% at 5 years). However, patients with the t(1;19) had a lower cumulative incidence of any hematological relapse (P=0.06; 0 vs 8.3+/-1.2% at 5 years) but a significantly higher incidence of central nervous system (CNS) relapse (P<0.001; 9.0+/-5.1% vs 1.0+/-0.4% at 5 years). In a multivariate analysis, the t(1;19) was an independent risk factor for isolated CNS relapse. These data suggest that with contemporary treatment, patients with the t(1;19) and TCF3/PBX1 fusion have a favorable overall outcome but increased risk of CNS relapse.

Clinical consequences of hyperglycemia during remission induction therapy for pediatric acute lymphoblastic leukemia

Hyperglycemia adversely affects outcome in adult patients with acute lymphoblastic leukemia (ALL), but its impact on children with this disease is unknown. We evaluated the relationship between hyperglycemia during remission induction therapy and clinical outcomes among pediatric patients with ALL. We reviewed the records of patients enrolled on four consecutive ALL protocols (Total Therapy protocols XIIIA, XIIIB, XIV and XV) at St Jude Children's Research Hospital from 1991 to 2007 and identified those who experienced hyperglycemia (glucose >or=200 mg per 100 ml) during remission induction. Complete remission (CR) rates at the end of induction, event-free survival (EFS), overall survival (OS), cumulative incidence of relapse and occurrence of infections were compared between those who did and did not experience hyperglycemia. Of 871 patients analyzed, 141 (16%) experienced hyperglycemia during remission induction. Patients with hyperglycemia were significantly older than the other patients (P<0.0001). There was no significant difference in CR rate (P=0.92), EFS (P=0.80), OS (P=0.28), cumulative incidence of relapse (P=0.59) or in the probability or types of infection between patients who did and did not experience hyperglycemia. Pediatric patients with or without hyperglycemia during remission induction for ALL have similar clinical outcome. Occurrence of hyperglycemia does not warrant alteration of the antileukemic regimen.

Effect of age and glycaemic control on the association between fibrinogen and risk of acute coronary events after transient ischaemic attack or stroke

BACKGROUND

Fibrinogen is an independent risk factor for acute vascular events, but there is uncertainty as to whether it is causal. One potential causal mechanism is the formation of low permeability fibrin clot in association with raised fibrinogen. We hypothesised that if this effect of fibrinogen were causally related to risk of vascular events, the risk relationship would be affected by the two other factors that affect fibrin clot permeability - age and glycaemic control.

METHODS

We studied the relationship between fibrinogen and risk of incident coronary events by age and baseline glucose levels in pooled data from three cohorts of patients with known cerebrovascular disease (UK-TIA Aspirin trial; Dutch TIA trial; Oxford TIA Study) during 23,272 patient-years of follow-up.

RESULTS

Risk of coronary events increased linearly with fibrinogen, but there was a significant interaction with age (p = 0.01 across tertiles of age), with the association being strongest for individuals aged <60 years (upper fibrinogen quintile hazard ratio = 3.95, 95% CI = 2.67-5.85, p < 0.0001). The risk relation was diminished in individuals with impaired glucose tolerance or diabetes. The effects of age and glycaemic control were independent, such that there was an almost fivefold increase in risk across quintiles of fibrinogen in patients aged <60 years with below median normal glucose levels (upper quintile hazard ratio = 4.90, 95% CI = 2.79-8.58, p < 0.0001).

CONCLUSIONS

The effect of age and glycaemic control on the relationship between fibrinogen and risk of acute coronary events supports the hypothesis of a causal effect of fibrinogen mediated via the permeability of fibrin clot.

Apolipoproteins as Predictors of Ischaemic Stroke in Patients with a Previous Transient Ischaemic Attack

BACKGROUND

Weak associations between total and LDL cholesterol and ischaemic stroke compared with coronary heart disease (CHD) are at odds with the similar effectiveness of statin drugs in preventing ischaemic stroke and CHD, suggesting that other lipid sub-fractions that are affected by statins might be better predictors of ischaemic stroke. Apolipoprotein B levels are reduced by statins and are a stronger predictor of CHD than total and LDL cholesterol in patients both on and off statins. However, there are very few published data on apolipoproteins and stroke risk and no studies in patients with previous transient ischaemic attack (TIA).

METHODS

We performed a prospective cohort study of the associations of baseline total cholesterol, LDL, HDL, apolipoproteins A1 and B (apo A1; apo B) and risk of ischaemic stroke in 261 patients with previous TIA. Cox proportional hazards models were used to determine crude and multivariate-adjusted hazard ratios (HR) above versus below median values at 10-years follow-up.

RESULTS

The apo B/apo A1 ratio was the strongest independent predictor of ischaemic stroke (HR=2.94, 95% CI 1.43-5.88, p=0.003) followed by apo B (HR=2.26, 95% CI 1.16-4.38, p=0.02). The associations between total cholesterol, LDL, HDL, LDL/HDL ratio and apo A1 and ischaemic stroke risk did not reach statistical significance.

CONCLUSIONS

Apo B and the apo B/apo A1 ratio are predictive of ischaemic stroke in patients with previous TIA. Further studies are required to determine whether the prognostic value of apolipoprotein levels is maintained in patients on statins.

Overt testicular disease at diagnosis of childhood acute lymphoblastic leukemia: lack of therapeutic role of local irradiation

To assess the prognosis of overt testicular disease at diagnosis of acute lymphoblastic leukemia, and any therapeutic role of irradiation for this involvement, we reviewed the data of 811 boys treated on St Jude studies Total X--XI (early period) and Total XII-XIV (recent period). In all, 19 boys (2.3%) had testicular disease at diagnosis. In the early period, patients with testicular leukemia had a poorer overall survival (OS) (P=0.003), event-free survival (EFS) (P=0.064), and higher cumulative incidence of relapse (P=0.041) than did other patients. During the recent period, patients with and without overt testicular leukemia did not differ in OS (P=0.257), EFS (P=0.102), or cumulative incidence of relapse (P=0.51). In a multivariate analysis, OS was lower for patients with testicular disease than for those without the involvement in the early period (P=0.047) but not in the recent one (P=0.75). Both patients who received irradiation for residual testicular disease at the end of induction subsequently died of leukemia. Of the other 17 patients who did not receive irradiation, only one developed testicular relapse in combination with bone marrow relapse. In conclusion, the prognostic impact of overt testicular disease has diminished. Irradiation appears to provide no survival advantage to this patient population.

Association between tea ingestion and invasive Bacillus cereus infection among children with cancer

Bacillus cereus is an emerging pathogen that causes invasive disease in immunocompromised hosts. A case-control study, prompted by a clinical case, demonstrated an association between dietary tea ingestion and B. cereus bacteremia. Policies designed to interrupt transmission of this pathogen to susceptible patients should be considered.

Change in stroke incidence, mortality, case-fatality, severity, and risk factors in Oxfordshire, UK from 1981 to 2004 (Oxford Vascular Study)

BACKGROUND

The incidence of stroke is predicted to rise because of the rapidly ageing population. However, over the past two decades, findings of randomised trials have identified several interventions that are effective in prevention of stroke. Reliable data on time-trends in stroke incidence, major risk factors, and use of preventive treatments in an ageing population are required to ascertain whether implementation of preventive strategies can offset the predicted rise in stroke incidence. We aimed to obtain these data.

METHODS

We ascertained changes in incidence of transient ischaemic attack and stroke, risk factors, and premorbid use of preventive treatments from 1981-84 (Oxford Community Stroke Project; OCSP) to 2002-04 (Oxford Vascular Study; OXVASC).

FINDINGS

Of 476 patients with transient ischaemic attacks or strokes in OXVASC, 262 strokes and 93 transient ischaemic attacks were incident events. Despite more complete case-ascertainment than in OCSP, age-adjusted and sex-adjusted incidence of first-ever stroke fell by 29% (relative incidence 0.71, 95% CI 0.61-0.83, p=0.0002). Incidence declined by more than 50% for primary intracerebral haemorrhage (0.47, 0.27-0.83, p=0.01) but was unchanged for subarachnoid haemorrhage (0.83, 0.44-1.57, p=0.57). Thus, although 28% more incident strokes (366 vs 286) were expected in OXVASC due to demographic change alone (33% increase in those aged 75 or older), the observed number fell (262 vs 286). Major reductions were recorded in mortality rates for incident stroke (0.63, 0.44-0.90, p=0.02) and in incidence of disabling or fatal stroke (0.60, 0.50-0.73, p<0.0001), but no change was seen in case-fatality due to incident stroke (17.2% vs 17.8%; age and sex adjusted relative risk 0.85, 95% CI 0.57-1.28, p=0.45). Comparison of premorbid risk factors revealed substantial reductions in the proportion of smokers, mean total cholesterol, and mean systolic and diastolic blood pressures and major increases in premorbid treatment with antiplatelet, lipid-lowering, and blood pressure lowering drugs (all p<0.0001).

INTERPRETATION

The age-specific incidence of major stroke in Oxfordshire has fallen by 40% over the past 20 years in association with increased use of preventive treatments and major reductions in premorbid risk factors.

Relationship Between Blood Pressure and Stroke Risk in Patients With Symptomatic Carotid Occlusive Disease

Background and Purpose— Blood pressure lowering in patients with a previous transient ischemic attack (TIA) or stroke reduces the risk of recurrent stroke and coronary vascular events. However, there is uncertainty about the risks and benefits in patients with severe carotid occlusive disease, particularly those with a carotid occlusion or bilateral ≥70% carotid stenosis in whom cerebral perfusion is often impaired and may depend directly on systemic blood pressure. Therefore, we studied the effect of carotid artery disease on the relationship between blood pressure and stroke risk in patients with recent TIA or stroke.

Methods— We compared the relationship between blood pressure (systolic and diastolic blood pressures, pulse pressure) and stroke risk in TIA and stroke patients with documented stenosis of at least 1 carotid artery [European Carotid Surgery Trial (ECST) and North American Symptomatic Carotid Endarterectomy Trial (NASCET)] with that in TIA and stroke patients with a low prevalence of carotid disease [United Kingdom Transient Ischaemic Attack (UK-TIA) Aspirin Trial]. In ECST and NASCET, we also determined the relationship between blood pressure and stroke risk in patients with unilateral carotid occlusion and patients with bilateral ≥70% carotid stenosis.

Results— Stroke risk on medical treatment increased with blood pressure in ECST and NASCET, but the relationships were less steep than in the UK-TIA trial. The relationship between blood pressure and stroke risk was not affected by the presence of a unilateral carotid occlusion but was significantly affected by the presence of bilateral carotid stenosis ≥70% (interaction: systolic blood pressure, P =0.002; diastolic blood pressure, P =0.03; pulse pressure, P =0.003). In this group, the relationship was inverted because of the high stroke risks at lower blood pressures. This interaction was not present after carotid endarterectomy and was not present for the risk of myocardial infarction.

Conclusions— The risk of stroke increases with blood pressure in the great majority of patients with symptomatic carotid artery disease, but the relationship is less steep than in other patients with TIA or stroke. The relationship is unaffected by unilateral carotid occlusion alone but is inverted in patients with bilateral ≥70% carotid stenosis, suggesting that aggressive blood pressure lowering may not be advisable in this group. These patients represent only a few percent of all patients with TIA or stroke but have a high risk of recurrent stroke.

Regression dilution of systolic and diastolic blood pressure in patients with established cerebrovascular disease

BACKGROUND AND OBJECTIVE

Blood pressure (BP) is a major risk factor for stroke and cardiovascular events. To quantify its effect, it is necessary to correct for regression dilution bias (RDB). RDB has been estimated from repeated measurements of BP in population-based studies, but there are no data in patients with established vascular disease.

METHOD

We analyzed repeat measurements of BP from three large studies of patients with cerebrovascular disease: UK-TIA trial (n=2098), Dutch TIA trial (n=2953), and the European Carotid Surgery Trial (n=2646). The regression dilution ratio (RDR) was estimated by parametric and nonparametric methods at follow-up intervals ranging from 4 months to 6 years.

RESULTS

After an interval of only 4-5 months, nonparametric RDRs of 0.56, 0.40, and 0.45 for systolic BP and 0.45, 0.33, and 0.31 for diastolic BP were observed in the three studies, respectively. These values are much smaller than those reported in population-based studies, indicating greater within-person variability in BP.

CONCLUSION

RDRs from population-based studies cannot necessarily be applied to cohorts with established vascular disease.

Urolithiasis in pediatric patients with acute lymphoblastic leukemia

We evaluated the incidence, timing, and consequences of urolithiasis in children with acute lymphoblastic leukemia (ALL). A total of 20 patients with urolithiasis were identified from 2095 patients with ALL treated at St Jude Children's Research Hospital on consecutive protocols between 1968 and 1998. For remission induction therapy, all patients received daily prednisone; continuation chemotherapy regimens differed by protocol with some including pulses of prednisone or dexamethasone and others no glucocorticoid. Patients with urolithiasis were older at diagnosis of ALL than those without urolithiasis (median age, 7.5 vs 5.0 years; P=0.03) and less likely to be black (P=0.03) than white or Hispanic, but sex and treatment era did not differ. Presenting symptoms included abdominal or flank pain, hematuria, and dysuria. All stones analyzed biochemically were calcium stones. The incidence of urolithiasis after completion of therapy was 1.8 per 10 000 person-years. Compared to this baseline rate, the relative risk of urolithiasis was 45 (P<0.01) during induction therapy, 22 (P<0.01) during continuation therapy with glucocorticoids, and 5.1 (P>0.05) during continuation therapy without glucocorticoids. Urolithiasis occurred 4.5 times more often during continuation treatment with glucocorticoids than without (P<0.05). Seven patients (35%) had recurrent urolithiasis. Patients with ALL are at risk of developing calcium renal stones during chemotherapy, especially when a glucocorticoid is included.

Spatial and intensity-dependent variations in associations between multiple species helminth infections

Estimated associations between infections with different helminth species can be used to predict the proportion of a population infected with multiple species infections. This is an important measure of disease burden, as those with multiple infections are often at an increased risk of morbidity. In this paper, we investigate variation amongst the estimated associations between Ascaris lumbricoides, Trichuris trichiura and hookworm, over a number of different spatial levels among schoolchildren in Cameroon. Associations between species were largely homogeneous within districts, provinces and ecological zones, although variation between these regions was identified, implying that a single measure of association may not be appropriate in different epidemiological settings. Further data collected amongst school children in Kenya and Uganda were analysed, to assess the dependence of the associations on the intensity of infection. It was found that the strength of the association between A. lumbricoides and T. trichiura increased with intensity, such that those with more intense infections with one species are increasingly likely to harbour concurrent intense infections with the other species. The implications of these results are discussed in relation to the estimation of the disease burden due to multiple helminth species.

Monoclonal antibody protects mice against infection and disease when given either before or up to 24 h after airborne challenge with virulent Venezuelan equine encephalitis virus

Airborne infection with Venezuelan equine encephalitis virus (VEEV) is a significant hazard for laboratory workers, who may not be immunised against VEEV infection as there is no vaccine currently available suitable for human use. We describe a potential alternative strategy that could protect workers exposed to VEEV or similar viruses. VEEV-specific murine monoclonal antibodies (MAB), given by intraperitoneal (i.p.) injection to mice as a single dose of 100 microg, have a half-life of 6-10 days in serum and spread by transudation to respiratory secretions. Administration of MAB (approximately 4 mg/kg) to mice 24h before challenge with approximately 100LD50 of virulent VEEV protected up to 100% animals. The same dose of MAB delivered up to 24h after challenge protected approximately 50%. Two MAB that were synergistic in vitro in plaque reduction neutralisation tests were not synergistic in vivo in protection assays. An examination of virus multiplication, in the blood and internal organs (brain, spleen, lung) of MAB-treated mice infected by the airborne route with VEEV, suggested that therapeutic activity depended both upon the prevention of virus infection of the brain, and the rapid clearance of virus from the periphery. Antiviral therapy with VEEV-specific human or "humanised" MAB, providing that they are administered early, may offer an alternative means of specific medical intervention for those with a known exposure to VEEV.

The Ras/PKA signaling pathway of Saccharomyces cerevisiae exhibits a functional interaction with the Sin4p complex of the RNA polymerase II holoenzyme

Saccharomyces cerevisiae cells enter into the G(0)-like resting state, stationary phase, in response to specific types of nutrient limitation. We have initiated a genetic analysis of this resting state and have identified a collection of rye mutants that exhibit a defective transcriptional response to nutrient deprivation. These transcriptional defects appear to disrupt the control of normal growth because the rye mutants are unable to enter into a normal stationary phase upon nutrient deprivation. In this study, we examined the mutants in the rye1 complementation group and found that rye1 mutants were also defective for stationary phase entry. Interestingly, the RYE1 gene was found to be identical to SIN4, a gene that encodes a component of the yeast Mediator complex within the RNA polymerase II holoenzyme. Moreover, mutations that affected proteins within the Sin4p module of the Mediator exhibited specific genetic interactions with the Ras protein signaling pathway. For example, mutations that elevated the levels of Ras signaling, like RAS2(val19), were synthetic lethal with sin4. In all, our data suggest that specific proteins within the RNA polymerase II holoenzyme might be targets of signal transduction pathways that are responsible for coordinating gene expression with cell growth.

Estimation of a time-varying force of infection and basic reproduction number with application to an outbreak of classical swine fever

BACKGROUND

A method was developed for stochastically reconstructing the pattern of infection from observed epidemic data. This allowed for estimation of a time-dependent force of infection, or transmission rate, during an epidemic.

METHODS

A discrete-time mechanistic model was used to describe the spread of infection and a stochastic procedure, which utilised the latent and infectious period distributions, was used to reconstruct the dates of infection, becoming infectious and removal from the given data. The four equations describing the model were then solved to obtain least squares estimates of the transmission rate and the basic reproduction number (R0) throughout the epidemic. This process was repeated in order to assess the variability in these key epidemiological parameters. The stochastic epidemic reconstruction procedure was developed to account for changes in the distribution of the survival period over the course of the epidemic and adapted for application to epidemic data where not all infected individuals have yet been observed as cases.

RESULTS

The method was applied to a set of epidemic data from an outbreak of classical swine fever in Pakistan. Constant and time-varying estimates of the transmission rate were derived and compared. There was some evidence to suggest that the force of infection varied over time.

DISCUSSION

The method described can be applied to data from epidemics where observations are incomplete. The confidence limits obtained for the estimated force of infection provide a means of assessing the evidence for time variation in this parameter.

Methods for estimation of associations between multiple species parasite infections

Human populations are often infected with more than one species of parasite, especially in developing countries where overall rates of parasitism are high. Infections with multiple parasite species may not necessarily be independent within an individual as physiological, immunological or ecological factors may result in positive or negative associations between infections with different parasite species. A general framework for estimation of these associations is presented. Data from over 215000 individuals are analysed and the associations between geohelminth (Ascaris lumbricoides, Trichuris trichiura and hookworm) and malaria species are investigated. A method is presented for analysing data from multiple communities and testing whether the associations in different communities are equal. Overall estimates of the associations between species are obtained for each country and continent where data were available. Associations between geohelminth species were, in general, found to be positive whilst both positive and negative associations were found between the different Plasmodium species. There was evidence for significant geographical heterogeneity between the associations. A method for using these parameter estimates to predict the distribution of multiple infections when only marginal prevalence data are available is described and demonstrated.

Hepatic veno-occlusive disease in children undergoing bone-marrow transplantation: usefulness of sonographic findings

BACKGROUND

Reports of the usefulness of ultrasonography in the diagnosis of hepatic veno-occlusive disease (HVOD) have presented conflicting results.

OBJECTIVE

To determine the usefulness of gray-scale or Doppler ultrasonographic measurements in the diagnosis of HVOD in pediatric patients undergoing BMT.

MATERIALS AND METHODS

We prospectively obtained 202 serial sonograms on 48 patients and examined the association between the clinical diagnosis of HVOD (McDonald criteria) and eight ultrasound parameters, including the hepatic artery resistive index (HARI), direction and velocity of portal venous flow, and thickness of the gall bladder wall.

RESULTS

HVOD developed in 29 of the 48 patients. The portal venous velocity increased after BMT in the group without HVOD and decreased in the group with HVOD; this difference was significant (P = 0.01). However, there was a great deal of variability in velocity measurements for individual patients. The mean HARI was 0.64 in the group with HVOD and 0.63 in the group without HVOD, and there was no difference between the two groups in the pattern of change in HARI relative to the day of BMT (P = 0.4). There was also no significant difference in thickness of the gallbladder wall between the two groups (P = 0.6).

CONCLUSION

No ultrasound parameter studied was as useful as the McDonald criteria for diagnosing HVOD.

The rye mutants identify a role for Ssn/Srb proteins of the RNA polymerase II holoenzyme during stationary phase entry in Saccharomyces cerevisiae

Saccharomyces cerevisiae cells enter into a distinct resting state, known as stationary phase, in response to specific types of nutrient deprivation. We have identified a collection of mutants that exhibited a defective transcriptional response to nutrient limitation and failed to enter into a normal stationary phase. These rye mutants were isolated on the basis of defects in the regulation of YGP1 expression. In wild-type cells, YGP1 levels increased during the growth arrest caused by nutrient deprivation or inactivation of the Ras signaling pathway. In contrast, the levels of YGP1 and related genes were significantly elevated in the rye mutants during log phase growth. The rye defects were not specific to this YGP1 response as these mutants also exhibited multiple defects in stationary phase properties, including an inability to survive periods of prolonged starvation. These data indicated that the RYE genes might encode important regulators of yeast cell growth. Interestingly, three of the RYE genes encoded the Ssn/Srb proteins, Srb9p, Srb10p, and Srb11p, which are associated with the RNA polymerase II holoenzyme. Thus, the RNA polymerase II holoenzyme may be a target of the signaling pathways responsible for coordinating yeast cell growth with nutrient availability.

Safety of lumbar puncture for children with acute lymphoblastic leukemia and thrombocytopenia

CONTEXT

Patients with thrombocytopenia are at risk for spontaneous or procedure-related hemorrhage. Whether such patients can safely undergo lumbar puncture (LP) without prophylactic platelet transfusion is unknown.

OBJECTIVE

To determine whether an association exists between thrombocytopenia and LP complications among children with acute lymphoblastic leukemia.

DESIGN, SETTING, AND PATIENTS

Retrospective review of the records of 958 consecutive children (median age, 5.5 years) with newly diagnosed acute lymphoblastic leukemia who were treated at a pediatric cancer center between February 1984 and July 1998.

INTERVENTIONS

All patients underwent a diagnostic LP followed by a median of 4 LPs to instill intrathecal chemotherapy.

MAIN OUTCOME MEASURE

Serious complications of LP occurring during the remission induction and consolidation treatment periods (when thrombocytopenia is likely to occur), defined as any neurologic, infectious, or hemorrhagic problems related to the procedure, reported by platelet count at the time of the procedure.

RESULTS

Of the 5223 LPs evaluated, 29 were performed at platelet counts of 10 x 10(9)/L or less, 170 at platelet counts of 11 to 20 x 10(9)/L, and 742 at platelet counts of 21 to 50 x 10(9)/L. No serious complications were encountered, regardless of the platelet count. The 95% confidence interval for the proportion of serious complications in the 199 patients with platelet counts of 20 x 10(9)/L or less was 0% to 1.75% and that for the 941 patients with platelet counts of 50 x 10(9)/L or less was 0% to 0.37%.

CONCLUSIONS

In our study of children undergoing remission induction or consolidation therapy for acute lymphoblastic leukemia, serious complications of LP were not observed, regardless of platelet count. Prophylactic platelet transfusion is not necessary in children with platelet counts higher than 10 x 10(9)/L. Due to the small number of patients in our study with platelet counts of 10 x 10(9)/L or less, conclusions cannot yet be drawn for such patients. JAMA. 2000;284:2222-2224.

The importance of immediate destruction in epidemics of foot and mouth disease

Foot and mouth disease is still prevalent in many parts of the world, as emphasised by the recent devastating epidemic in pig farms in Taiwan. A discrete time mechanistic model has been used to describe the spread of infection in both this epidemic and the 1967 to 1968 epidemic in the UK. The force of infection and basic reproduction number are estimated and the sensitivity of these results to the distributions of both the latent and infectious periods of the disease is examined. Epidemic simulations were performed to evaluate the disease control policy whereby all herds are slaughtered on the same day as disease confirmation. These simulations showed that implementing this policy could have resulted in a dramatic reduction (of over 60 per cent) in the number of pig farms affected in the Taiwan epidemic. It is thus imperative that the necessary resources are available to implement this policy, should an outbreak occur.

Evidence for a mass community effect of insecticide-treated bednets on the incidence of malaria on the Kenyan coast

The use of insecticide-treated bednets (ITBNs) has been shown to be effective in reducing mortality and morbidity from malaria. However, there is mixed evidence as to whether or not community-wide use of ITBNs engenders a 'mass effect', such that those not sleeping under bednets are offered protection from widespread ITBN use in the area in which they live. We have analysed data collected in Kilifi, Kenya, from a cohort of children followed from birth to investigate how the degree of net usage in the locality of a child affects the risk of developing malaria. This effect was explored using a Cox proportional hazards model. For those not using ITBNs, we found that an increasing level of ITBN usage within the area surrounding each child was associated with a decreasing risk of developing malaria, thus providing evidence in support of a mass community effect. The size and significance of this effect were found to decrease as non-overlapping areas of increasing distance away from a child's home were considered. The effect was significant for areas at distances of up to 1.5 km away from each child.

Paediatric survival and re-admission risks following hospitalization on the Kenyan coast

The district general hospital (DGH) is a common feature of health service provision in many developing countries. We have used linked demographic and clinical surveillance in a rural community located close to a DGH on the Kenyan coast to define the use and public health significance of essential clinical services provided by it. Of a birth cohort of over 4000 children followed for approximately 6 years, about a third were admitted to hospital at least once. Significantly more children admitted with major infectious diseases such as malaria and acute respiratory tract infections were readmitted with the same condition during the surveillance period than would have been expected by chance. Among surviving admissions, mortality post-discharge was significantly higher than in the cohort which had not been admitted within 3, 6 and 12 months. Most of the patients who died after discharge had been admitted with a diagnosis of gastroenteritis. Most children admitted to the DGH survive hospitalization and the remaining period of childhood. Despite no clinical trial evidence to support the claim, it seems reasonable to assume that in the absence of intensive clinical management provided by a DGH, a significant proportion of these children would not have survived. However, the DGH is able to define a group of at-risk children who re-present with severe complications of infectious disease, and of these several may have underlying conditions not amenable to DGH intervention and continue to have a poor prognosis. Both groups of children represent statistically significant subsets of a rural paediatric community and the future organization and co-ordination of DGH and primary care services need to work in unison to strengthen the service needs of children at risk.

Discovery of a novel series of selective MMP inhibitors: identification of the gamma-sulfone-thiols

We have discovered a new series of potent MMP Inhibitors that are selective for MMP-13 over MMP-1 incorporating a gamma-sulfone thiol.

Serious hepatitis A: an analysis of patients hospitalized during an urban epidemic in the United States

BACKGROUND

Memphis and Shelby County, Tennessee, experienced an epidemic of hepatitis A in 1994 and 1995. More than 1700 cases were reported.

OBJECTIVE

To characterize the clinical features of patients hospitalized during a large urban epidemic of hepatitis A.

DESIGN

Retrospective chart review.

SETTING

15 acute care hospitals in Shelby County, Tennessee.

PATIENTS

256 patients hospitalized with acute hepatitis A.

MEASUREMENTS

Laboratory findings (such as prothrombin time and bilirubin level), complications, and mortality.

RESULTS

The median patient age was 26 years. Thirty-nine complications occurred in 35 patients. Twenty patients (8%) had extrahepatic complications, and 5 (2%) died. Patients 40 years of age and older were more likely to have serious complications, including death (P = 0.014). Sixty-seven patients (26%) presented with coagulopathy (prothrombin time > or = 3 seconds prolonged). Fifty-four patients (21%) had a bilirubin level greater than 170 micromol/L (10 mg/dL).

CONCLUSIONS

During this epidemic, hepatitis A caused serious illness and death. Complications were more frequent in patients 40 years of age and older, but young, healthy persons were also at risk for severe complications.

A peptidomimetic that specifically inhibits human leukocyte antigen DRB1*0401-restricted T cell proliferation

The ability of a peptidomimetic (SC-67655) to block the peptide binding site of the rheumatoid arthritis-linked human leukocyte antigen encoded by the DRB1*0401 allele was evaluated. The inhibitor bound to purified DRB1*0401 molecules with an affinity similar to that of the well-characterized peptide ligand HA307-319. Cell binding assays demonstrated that, in contrast to the promiscuous HA307-319 peptide, the peptidomimetic was highly specific for DRB1*0401. The inhibitor also blocked functional T cell responses to peptide antigens but did not block T cell proliferation in response to protein antigens. Furthermore, it did not appear to be taken up by cells. An analog of the peptidomimetic that was conjugated to a signal peptide sequence did inhibit a T cell proliferative response to protein antigen. Thus, the peptidomimetic must be taken up by cells to block the presentation of peptides derived from protein antigens. These findings have implications for the rational development of inhibitors that block the class II peptide binding groove for the treatment of autoimmune diseases.

A peptide isolated by phage display binds to ICAM-1 and inhibits binding to LFA-1

A mixed phage library containing random peptides from four to eight residues in length flanked by cysteine residues was screened using a recombinant soluble, form of human ICAM-1, which included residues 1-453, (ICAM-1(1-453)). Phage bound to immobilized ICAM-1(1-453) were eluted by three methods: (1) soluble ICAM-1(1-453), (2) neutralizing murine monoclonal antibody, (anti-ICAM-1, M174F5B7), (3) acidic conditions. After three rounds of binding and elution, a single, unique ICAM-1 binding phage bearing the peptide EWCEYLGGYLRCYA was isolated; the identical phage was selected with each method of elution. Attempts to isolate phage from non-constrained (i.e., not containing cysteines) libraries did not yield a phage that bound to ICAM-1. Phage displaying EWCEYLGGYLRCYA bound to immobilized ICAM-1(1-453) and to ICAM-1(1-185), a recombinant ICAM-1, which contains only the two amino-terminal immunoglobulin domains residing within residues 1-185. This is the region of the ICAM-1 that is bound by LFA-1. The phage did not bind to proteins other than ICAM-1. The phage bound to two ICAM-1 mutants, which contained amino acid substitutions that dramatically decreased or eliminated the binding to LFA-1. Studies were also performed with the corresponding synthetic peptide. The linear form of the synthetic EWCEYLGGYLRCYA peptide was found to inhibit LFA-1 binding to immobilized ICAM-1(1-453) in a protein-protein binding assay. By contrast, the disulfide, cyclized, form of the peptide was inactive. The EWCEYL portion of the sequence is homologous to the EWPEYL sequence found within rhinovirus coat protein 14, a nonintegrin protein that binds to ICAM-1. Taken together, the results suggests that the EWCEYLGGYLRCYA sequence is capable to binding to immobilized ICAM-1. Phage display appears to represent a new approach for the identification of peptides that interfere with ICAM-1 binding to beta 2 integrins.

Utilization of multiple phage display libraries for the identification of dissimilar peptide motifs that bind to a B7-1 monoclonal antibody

Seven random peptide libraries (two displaying linear peptides and five displaying cysteine-constrained peptides) were constructed as gene III fusion proteins of the bacteriophage fd-tet. These libraries were used to screen a blocking monoclonal antibody raised against B7-1 (CD80), a human cell surface antigen that binds two T cell receptors, CD28 and CTLA-4. After three rounds of screening against the immobilized antibody, 1000-fold enrichment was observed in libraries displaying both linear and cysteine-constrained peptides. DNA sequencing of the enriched phage revealed two distinct consensus sequences: HXG(A/Y)XH and DVCXXGGPGC. Phage expressing these consensus sequences bound to L307.4 but not to an isotype matched antibody, indicating that binding was antibody specific. Synthetic peptides corresponding to both motifs inhibited phage binding to L307.4, indicating that the gene III protein is not required for peptide binding. In addition, the cyclized forms of synthetic peptides containing the DVCXXGGPGC motif were capable of inhibiting L307.4 binding to soluble B7-1/Fc fusion. Moreover, phage expressing only the HXG(A/Y)XH consensus sequence were inhibited from binding to L307.4 by the presence of chelating agents. These results indicate that the framework within which the peptide is presented on the surface of the phage may allow the identification of unique peptide motifs with distinct binding characteristics. These peptide motifs could be used for the design of peptidomimetics with therapeutic applications if they inhibit the binding of B7-1 to its T cell receptors.

Naturally processed peptides from rheumatoid arthritis associated and non-associated HLA-DR alleles

Naturally processed peptides from immunoaffinity-purified HLA-DRB1*0401, -DRB1*0404 (rheumatoid arthritis (RA)-associated), and -DRB1*0402 (non-RA-associated) molecules were analyzed by capillary liquid chromatography and mass spectrometry. The molecular weights observed for more than 60 eluted peptides from each HLA-DR protein ranged from 788 to 3535 atomic mass units, corresponding to peptides 7 to 32 amino acids in length. Sequencing of more than 60 of the abundant peptides revealed nested sets of peptides that were derived from only 12 different proteins. The majority of these proteins were membrane-associated (HLA class I, class II, and Ig molecules). Synthetic peptides, corresponding to endogenous peptide sequences, bound with high affinity (5 to 80 nM) to the HLA-DR molecules from which they were eluted. In addition, most were promiscuous binding peptides in that they also bound to other HLA-DR molecules. Truncations of eluted peptide sequences and alanine scanning mutational analysis of a Mycobacterium leprae peptide were used to identify the peptide residues involved in binding to DRB1*0404 and DRB1*0402 molecules. Furthermore, an invariant chain peptide was eluted from the DRB1*0402 molecules but not from the RA-associated molecules. The lack of invariant chain peptides from DRB1*0401 and DRB1*0404 molecules may contribute to the loading of autoantigen peptides into these molecules and to their association with disease.

Naturally processed peptides from rheumatoid arthritis associated and non-associated HLA-DR alleles

Naturally processed peptides from immunoaffinity-purified HLA-DRB1*0401, -DRB1*0404 (rheumatoid arthritis (RA)-associated), and -DRB1*0402 (non-RA-associated) molecules were analyzed by capillary liquid chromatography and mass spectrometry. The molecular weights observed for more than 60 eluted peptides from each HLA-DR protein ranged from 788 to 3535 atomic mass units, corresponding to peptides 7 to 32 amino acids in length. Sequencing of more than 60 of the abundant peptides revealed nested sets of peptides that were derived from only 12 different proteins. The majority of these proteins were membrane-associated (HLA class I, class II, and Ig molecules). Synthetic peptides, corresponding to endogenous peptide sequences, bound with high affinity (5 to 80 nM) to the HLA-DR molecules from which they were eluted. In addition, most were promiscuous binding peptides in that they also bound to other HLA-DR molecules. Truncations of eluted peptide sequences and alanine scanning mutational analysis of a Mycobacterium leprae peptide were used to identify the peptide residues involved in binding to DRB1*0404 and DRB1*0402 molecules. Furthermore, an invariant chain peptide was eluted from the DRB1*0402 molecules but not from the RA-associated molecules. The lack of invariant chain peptides from DRB1*0401 and DRB1*0404 molecules may contribute to the loading of autoantigen peptides into these molecules and to their association with disease.

Identification and preliminary characterization of a chitinase gene in the Autographa californica nuclear polyhedrosis virus genome

A functional chitinase gene (chiA) has been identified in the genome of the Autographa californica nuclear polyhedrosis virus (AcMNPV). It is expressed in the late phase of virus replication in insect cells. High levels of both endo- and exochitinase activity were detected by 12 hr p.i. and remained stable throughout infection. An AcMNPV chiA protein-specific antibody was prepared using recombinant material prepared in bacteria. This was used to demonstrate that a product of approximately 58 kDa was synthesised in virus-infected cells. Immunofluorescence analysis of virus-infected cells showed that most chitinase was located in the cytoplasm. Primer extension analysis of mRNA from AcMNPV-infected cells confirmed that transcription initiated from a baculovirus late start site (TAAG), 14 nucleotides upstream from the putative translation initiation codon. The predicted protein sequence of the AcMNPV chiA shares extensive sequence similarity with chitinases from bacteria and, in particular, the Serratia marcescens chitinase A (60.5% identical residues). Phylogenetic analyses indicate that AcMNPV, or an ancestral baculovirus, acquired the chitinase gene from a bacterium via horizontal gene transfer.

Intratracheal administration of endotoxin and cytokines. VI. Antiserum to CINC inhibits acute inflammation

Cytokine-induced neutrophil chemoattractant (CINC), a chemotactic molecule of the interleukin (IL)-8 family, is known to be induced in the rat in response to tumor necrosis factor (TNF), IL-1, and lipopolysaccharide (LPS). Intratracheal injection of endotoxin (LPS) is shown to cause CINC mRNA expression in pulmonary tissue, peaking after 2 h, and CINC protein expression in bronchoalveolar lavage (BAL) fluid, peaking after 2-4 h. Intratracheal injection of synthetic CINC causes acute inflammation that is abrogated by coinjection of antiserum to purified natural rat CINC. Intratracheal injection of antiserum to CINC inhibits intratracheal LPS- and IL-1-induced neutrophil emigration into BAL fluid by approximately 60-70%. Despite the anti-inflammatory activity of anti-CINC antiserum, TNF is elevated in the lavage fluid of rats receiving anti-CINC, suggesting that CINC may act in a negative feedback loop to downregulate TNF expression. Intratracheal injection of antiserum to CINC combined with intravenous injection of anti-E-selectin antibody inhibits intratracheal LPS- and IL-1-induced neutrophil emigration into BAL fluid by approximately 75-85%. CINC-mediated chemotactic activity and E-selectin-mediated adherence of neutrophils to endothelium contribute significantly to the pathogenesis of LPS-initiated acute inflammation.

Binding of sialyl Lewis x to E-selectin as measured by fluorescence polarization

Fluorescence polarization has been used to directly measure the binding of the tetrasaccharide sialyl Lewisx (sLe(x)[Glc], or NeuAc alpha 2-3Gal beta 1-4[Fuc alpha 1-3]Glc) to a soluble form of E-selectin, a member of the class of adhesion molecules that plays an important role in immune-cell response to inflammation. The experiments utilized a fluorescent derivative of sLe(x)[Glc] with fluorescein attached directly to the glucose residue through a beta-glycosidic linkage. The resulting fluorescent sLe(x) was shown to inhibit binding of HL60 cells to immobilized E-selectin and exhibited fluorescence polarization enhancement in the presence of a monovalent form of a recombinant soluble E-selectin-Fc chimera. Thermodynamic dissociation constants of 107 +/- 26 and 120 +/- 31 microM were obtained for the fluorescent sLe(x)[Glc] and the free sLe(x)[Glc] sugars, respectively. These results demonstrate that E-selectin interacts weakly with the minimal carbohydrate recognition determinant sLe(x). Additional binding interactions through the action of the authentic coreceptor or via clustering of the ligand and E-selectin molecules on the respective neutrophil and endothelial cell surfaces may also play a role in the overall cellular binding strength. However, the basic interaction between carbohydrate and protein appears weak, consistent with other carbohydrate-protein interactions studied to date.

Studies on selectin-carbohydrate interactions

Recruitment of neutrophils to sites of inflammation is now believed to occur through an initial rolling interaction at the luminal surface of activated endothelium and is mediated by a class of mammalian lectins referred to as the selectins. Selectins recognize carbohydrate determinants on co-receptors. It is generally believed that many selectin molecules must bind to many carbohydrate receptor molecules i.e. multivalent binding, to enable sufficient binding strength to elicit the rolling response between the neutrophil and the endothelial cell. One of the approaches to the generation of more potent molecular antagonists of the selectin-mediated cell-cell interaction is to mimic the multivalent interaction in a single compound. Recent experiments utilising conjugated forms of sialyl Lewisx-BSA have explored this feasibility (Welply et al., 1994). In that study, monovalent sLex (sialic acid alpha 2-3Gal beta 1-4(Fuc alpha 1-3)GlcNAc), the minimum binding determinant for E-selectin, as well as monovalent sialyllactosamine (sialic acid alpha 2-3Gal beta 1-4GlcNAc), a non-binding structure, and the corresponding multivalent BSA-conjugated forms were tested for their ability to inhibit binding of HL-60 cells to immobilised E-selectin. As expected, only sLex and sLex-BSA were found to do so. sLex16-BSA (16 mol tetrasaccharide/mol BSA) showed a dose-dependent inhibition of HL-60 binding with a measured IC50 of 1 microM; demonstrating close to a three-order of magnitude enhancement of inhibitory activity compared to free sLex. This result indicated that multivalent forms of sLex are capable of binding to E-selectin with higher affinity than do monovalent glycans. In another study, fluorescent forms of monovalent sLex were synthesized and used to measure a true thermodynamic dissociation constant for the monovalent sLex:E-selectin interaction of 120 +/- 31 microM (Jacob et.al., 1995).

The complete DNA sequence of Autographa californica nuclear polyhedrosis virus

The complete nucleotide sequence of the genome of clone 6 of the baculovirus Autographa californica nuclear polyhedrosis virus (AcNPV) has been determined. The molecule comprises 133,894 base pairs and has an overall A + T content of 59%. Our analysis suggests that the virus encodes some 154 methionine-initiated, and potentially expressed, open reading frames (ORFs) of 150 nucleotides or greater. These ORFs are distributed evenly throughout the virus genome on either strand. The ORFs are arranged as adjacent, nonoverlapping reading frames separated by short intergenic regions. Based on the primary nucleotide sequence, predictions have been made concerning the functions of certain genes, the sites for initiation of viral DNA replication, the regulation of early and late gene transcription, and factors that may affect the AcNPV gene translational efficiency. The genome sequence data confirm, with minor differences, the information obtained for other AcNPV clones. It is proposed that clone C6 is considered the archetype AcNPV for comparison purposes.