Pharmaceutical Industry Payments to Medical Oncologists in the Netherlands: Trends and Patterns Provided by an Open-Access Transparency Data Set

PURPOSE

Health care expenditure related to oncologic treatments is skyrocketing although many treatments offer marginal, if any, clinical benefit. Financial conflicts of interest (fCOI) resulting from pharmaceutical industry (pharma) payments to physicians is increasingly recognized as a predictive factor for regulatory board approval and guideline incorporation of low-value treatments. We sought to study the extent to which pharma payments to medical oncologists occur in the Netherlands, the amount of money involved, and whether these occur more frequently and are higher for key opinion leaders (KOLs).

METHODS

In our cross-sectional retrospective database study, we used several Dutch open-access databases and extracted data registered between 2019 and 2021.

RESULTS

A cumulative amount of €899,863 was paid to 48.8% of the 408 registered medical oncologists. Over time, there was a marked decline in both the proportion of medical oncologists receiving payments (from 40.4% in 2019 to 19.1% in 2021) and the mean annual value of payments (from €2,962 in 2019 to €2,188 in 2021) with the latter mainly resulting from a decline in hospitality-related transactions. KOLs were more likely to receive industry payments and received a higher median payment value.

DISCUSSION

Our findings should contribute to the increasing awareness in the Netherlands of the potential effects of fCOI.

The role of the clinical laboratory in diagnosing acid-base disorders

Acid-base homeostasis is fundamental for life. The body is exceptionally sensitive to changes in pH, and as a result, potent mechanisms exist to regulate the body's acid-base balance to maintain it in a very narrow range. Accurate and timely interpretation of an acid-base disorder can be lifesaving but establishing a correct diagnosis may be challenging. The underlying cause of the acid-base disorder is generally responsible for a patient's signs and symptoms, but laboratory results and their integration into the clinical picture is crucial. Important acid-base parameters are often available within minutes in the acute hospital care setting, and with basic knowledge it should be easy to establish the diagnosis with a stepwise approach. Unfortunately, many caveats exist, beginning in the pre-analytical phase. In the post-analytical phase, studies on the arterial reference pH are scarce and therefore many different reference values are used in the literature without any solid evidence. The prediction models that are currently used to assess the acid-base status are approximations that are mostly based on older studies with several limitations. The two most commonly used methods are the physiological method and the base excess method, both easy to use. The secondary response equations in the base excess method are the most convenient. Evaluation of acid-base disorders should always include the assessment of electrolytes and the anion gap. A major limitation of the current acid-base laboratory tests available is the lack of rapid point-of-care laboratory tests to diagnose intoxications with toxic alcohols. These intoxications can be fatal if not recognized and treated within minutes to hours. The surrogate use of the osmolal gap is often an inadequate substitute in this respect. This article reviews the role of the clinical laboratory to evaluate acid-base disorders.

Climate Factors as Important Determinants of Dengue Incidence in Curaçao

Macro- and microclimates may have variable impact on dengue incidence in different settings. We estimated the short-term impact and delayed effects of climate variables on dengue morbidity in Curaçao. Monthly dengue incidence data from 1999 to 2009 were included to estimate the short-term influences of climate variables by employing wavelet analysis, generalized additive models (GAM) and distributed lag nonlinear models (DLNM) on rainfall, temperature and relative humidity in relation to dengue incidence. Dengue incidence showed a significant irregular 4-year multi-annual cycle associated with climate variables. Based on GAM, temperature showed a U-shape, while humidity and rainfall exhibited a dome-shaped association, suggesting that deviation from mean temperature increases and deviation from mean humidity and rainfall decreases dengue incidence, respectively. Rainfall was associated with an immediate increase in dengue incidence of 4.1% (95% CI: 2.2-8.1%) after a 10-mm increase, with a maximum increase of 6.5% (95% CI: 3.2-10.0%) after 1.5 month lag. A 1 °C decrease of mean temperature was associated with a RR of 17.4% (95% CI: 11.2-27.0%); the effect was inversed for a 1°C increase of mean temperature (RR= 0.457, 95% CI: 0.278-0.752). Climate variables are important determinants of dengue incidence and provide insight into its short-term effects. An increase in mean temperature was associated with lower dengue incidence, whereas lower temperatures were associated with higher dengue incidence.

Global health and transfusion medicine: education and training in developing countries

Education and training in transfusion medicine have improved over the past decade in developing countries but are still generally deficient for the purpose of maintaining the safety of the global blood supply. In 2009, the World Health Organization global database on blood safety indicated that only 72% of countries in the world were able to meet their training needs necessary for maintaining the safety of their local blood supply. Educational approaches in transfusion medicine vary widely between continents and world regions. In this article, we summarize a session on global health education and training in developing countries that took place at the 2012 AABB conference. The panel consisted of transfusion representatives from South America (Brazil), Asia (China), Africa (South Africa), and the Caribbean (Curaçao), as well as a description of capacitation issues in postearthquake Haiti and the pivotal role of the US President's Emergency Plan for AIDS Relief (PEPFAR) in transfusion training and education in Africa. We present here summaries of each of these panel presentations.

A case study of the implementation of a competency-based curriculum in a Caribbean teaching hospital

OBJECTIVE

Several teaching hospitals are currently modifying their curriculum to comply with the changing demands in medical education. As a result, we decided to evaluate whether a competency-based curriculum implemented in a Caribbean teaching hospital fulfilled the requirements as defined by the CanMEDS framework.

METHODS

We made use of a triangulation method in the survey to obtain information on the educational process. Two separate methods were used consisting of site visits by visiting professors and a medical educator. The focus was on the structure, content and assessments of the educational activities.

RESULTS

Major recommendations included increased involvement of medical specialists in the educational activities in the clinical workplace. There was need for improvement of communication between medical specialists, patients, nurses, trainees and residents. Overall, improvements were observed in the structure of clinical rotations and content of the training programme.

CONCLUSION

The implemented assessment programme provided necessary information for effective evaluation of the competency-based curriculum. We were able to identify new and feasible methods for improving the curriculum in our educational setting.

Epidemiology of febrile diseases in the emergency department of a Caribbean island: the Curaçao experience

OBJECTIVE

The aetiology of febrile diseases in tropical countries often remains poorly characterized. We aim to describe the aetiology and outcome of febrile illnesses at the Emergency Department (ED) in Curaçao.

METHODS

From April 2008 - April 2009, all adult febrile patients (T> 38.5 degrees C) at the ED of the St Elisabeth Hospital, Curaçao, Netherlands Antilles, were included. Clinical data were recorded, routine laboratory measurements and blood cultures were taken. Final diagnoses were made at discharge by an independent physician and in retrospect by the main investigator

RESULTS

Four hundred and three patients were included: 223 patients (55.6%) were hospitalized, 32 patients (7.9%) died and 18 patients (4.5%) were admitted to the Intensive Care Unit. In 129 febrile patients (32.0%), infection was proven; 84.4% of patients had bacterial (29.0% urinary tract infection, 23.2% pneumonia infection), 5.6% viral and 10.0% parasitic or fungal infections. Twenty-one patients (5.2%) were discharged with a non-infectious diagnosis and 172 patients (42.7%) without a clear diagnosis.

CONCLUSION

A high mortality rate of 7.9% was observed. We found a high prevalence of bacterial infections, with pneumonia and urinary tract infections as the most common causes of fever. One in 20 patients did not have an infectious disease.

One-year epidemiology of fever at the Emergency Department

BACKGROUND

Although fever is recognised as a major presentation symptom at Emergency Departments (EDs) and is often used as a rationale for the institution of antibiotics, few studies describing patients with fever as the sole inclusion criterion at the ED of a general hospital have been performed. The objective of this study is to describe epidemiology of non-surgical febrile patients at the ED and to identify risk factors for adverse outcome.

METHODS

Blood, sputum, urine and faeces cultures, urine sediments and throat swaps for viral diagnostics were obtained from febrile ED patients. Outcome parameters were bacterial/viral infection, non-bacterial/non-viral infection, non-infectious febrile disease; mortality, hospital admission, admission to the intensive care unit (ICU) and length of hospital stay.

RESULTS

213 Patients were included (87.8% were hospitalised, 8.5% were admitted to ICU, 4.2% died). In 75 patients (35.2%), bacterial infection was confirmed; in 78 patients (36.6%) bacterial infection was suspected. In nine patients (4.2%), viral diagnosis was confirmed; in six patients (2.8%), a viral condition was suspected. The most frequently encountered infection was bacterial pneumonia (58 patients, 27.2%). Only older age was correlated with mortality (ρ=0.176, p=0.01).

CONCLUSION

A majority of the febrile patients were admitted to the hospital, mostly for bacterial infection. An overall mortality rate of 4.2% was registered. Only a few risk factors for adverse outcome could be identified in this cohort. Overall, the outcome of patients presenting with fever at the ED is rather benign.

The diagnostic role of procalcitonin and other biomarkers in discriminating infectious from non-infectious fever

Fever is not only observed in the course of a bacterial or viral infection, but can be a symptom of, for instance, auto-immune, malignant or thromboembolic disease. Determining the etiology of fever in a fast and reliable way is of pivotal importance, as different causes of fever may ask for different therapies. Neither clinical signs and symptoms, nor traditional biomarkers, such as CRP, leukocytes and ESR have sufficient sensitivity and specificity to guide treatment decisions. In this review we focus on the value of traditional and newer biomarkers in non-infectious febrile diseases. Procalcitonin (PCT) seems to be the most helpful laboratory marker for the differentiation of causes of fever, particularly in autoimmune, autoinflammatory and malignant diseases.

Plasma annexin A5 and microparticle phosphatidylserine levels are elevated in sickle cell disease and increase further during painful crisis

Expression of phosphatidylserine (PS) on the membrane surface of red blood cells and circulating microparticles (MP) plays an important role in etiology of the hypercoagulable state of sickle cell disease (SCD), as well as in the reduced red cell life span and adhesive interactions between red cells and endothelium. Annexin A5, an intracellular protein abundantly present in endothelial cells and platelets, exhibits high affinity for PS and has been shown to inhibit several of these PS-mediated pathophysiological processes. We determined plasma annexin A5 levels and MP-associated procoagulant activity, a measure of MP-PS exposure, in 17 sickle cell patients (12 HbSS and 5 HbSC) in steady state and at presentation with a painful crisis. Twenty-five HbAA blood donors served as controls. Both annexin A5 and MP-PS were highest in HbSS patients (5.7 ng/mL, IQR 3.7-7.6 and 37.9 nM, IQR 31.9-69.8) as compared to HbSC patients (1.8 ng/mL, IQR 1.7-7.6 and 20.9 nM, IQR 10.9-29.6) and healthy controls (2.5 ng/mL, IQR 1.4-4.4 and 13.1 nM, IQR 9.5-18.5) (p=0.01 and p<0.001, respectively). At presentation with a painful crisis, annexin A5 and MP-PS had increased in 16 of 17 patients (p=0.001 and p<0.001, respectively). Most interestingly, in 7 HbSS patients the proportional increase in MP-PS exposure was higher than the proportional increase in plasma annexin A5 concentration, leading to lower annexin A5/MP-PS ratio of HbSS patients during crisis than HbAA controls (0.0027 (0.0017-0.0049) vs 0.0048 (0.0027-0.0085), p=0.05). In conclusion, patients with SCD have elevated plasma levels of annexin A5- and PS-exposing MP. During crisis both levels increase, but in most HbSS patients MP-PS exposure increases more than annexin A5. Future studies must address a potential role of annexin A5 in modulating PS-related pathophysiological processes in SCD.

Elevated circulating stromal-derived factor-1 levels in sickle cell disease

Inflammation and angiogenesis are of importance in the pathophysiology of sickle cell disease (SCD). Recently, the chemokine stromal-derived factor-1 (SDF-1) has been shown to be a key mediator of angiogenesis and inflammation. In this study we determined serum SDF-1 levels in consecutive adult sickle cell patients during the clinically asymptomatic state as well as during painful crisis. Serum SDF-1 levels were significantly elevated in HbSS/HbSbeta(0)-thalassaemia patients [n = 42; 5,177 pg/ml (2,438-7,246)] compared to HbSC/HbSbeta(+)-thalassaemia patients [n = 16; 2,405 pg/ml (1,365-3,047)] and healthy HbAA controls [n = 45; 2,894 pg/ml (2,577-3,334)] (p = 0.001). No significant increments were observed during painful crisis (n = 40). SDF-1 levels were significantly higher in SCD patients with pulmonary hypertension (PHT) compared to patients without PHT. Elevated circulating SDF-1 levels occur in patients with SCD and may play a role in the pathophysiology of SCD-related PHT.

Increased serum levels of anti-angiogenic factors soluble fms-like tyrosine kinase and soluble endoglin in sickle cell disease

The anti-angiogenic factors soluble fms-like tyrosine kinase (sFlt)-1 and soluble endoglin (sEng) have been shown to be of importance in angiogenesis by sequestering and inhibiting vascular endothelial growth factor, placenta-like growth factor and transforming growth factor-beta(1) signaling. Given the potential role of angiogenesis in the pathophysiology of sickle cell disease (SCD)-related complications, serum levels of sFlt-1 and sEng were determined in SCD patients and controls. Both sFlt-1 (p = 0.002) and sEng (p = 0.004) were elevated in patients during clinically asymptomatic SCD with no further increment during painful crisis. These data suggest that sFlt-1 and sEng may be important in the regulation of angiogenesis in SCD.

Plasma levels of asymmetric dimethylarginine (ADMA), an endogenous nitric oxide synthase inhibitor, are elevated in sickle cell disease

In recent years an important role has been ascribed to a reduced nitric oxide (NO) availability in the pathophysiology of sickle cell disease (SCD). Endogenously produced inhibitors of NO synthase, in particular asymmetric dimethylarginine (ADMA), are currently considered of importance in various vascular disease states characterized by reduced NO availability. We determined ADMA levels in plasma of 12 adult sickle cell patients (eight HbSS and four HbSC), and compared these to plasma levels in race- and age-matched controls. Sickle cell patients were characterized by strongly elevated levels of ADMA [HbSS: median 0.63 micromol/l (interquartile range 0.54-0.85), HbSC: 0.43 micromol/l (0.40-0.46), HbAA: 0.33 micromol/l (0.32-0.35) p<0.001]. ADMA levels were highest in HbSS patients with lowest hemoglobin levels and highest leukocyte counts, and in HbSS patients ADMA levels were positively associated with serum levels of soluble vascular cell adhesion molecule-1. These results suggest an important role of ADMA in limiting NO availability in SCD, and its role in the pathophysiology of SCD should be further investigated.

Sickle cell disease; a general overview

Sickle cell disease (SCD) is a heterogeneous disorder, with clinical manifestations including chronic haemolysis, an increased susceptibility to infections and vaso-occlusive complications often requiring medical care. Patients with SCD can develop specific and sometimes life-threatening complications, as well as extensive organ damage reducing both their quality of life and their life expectancy. Proven effective treatment options for sickle cell patients are limited to hydroxyurea, blood transfusions and bone marrow transplantation. With the increasing prevalence of SCD in the Netherlands, a fundamental understanding of its pathophysiology and clinical syndromes is of importance for local medical practitioners.

Protein C and S and inflammation in sickle cell disease

Reduced activity of naturally occurring anticoagulants (NOAC) protein C and protein S may contribute to vaso-occlusion in sickle cell disease (SCD). We studied whether protein C and S are related to clinical vaso-occlusion, hematological markers of disease severity (hemoglobin levels, leukocyte counts, and percentage of fetal hemoglobin), and inflammation in SCD. Protein C activity, protein S (free and total) antigen, endothelial activation markers (soluble vascular cell adhesion molecule-1 [sVCAM-1], von Willebrand antigen [vWF]), and high sensitive C-reactive protein (hsCRP) levels were measured in 30 HbSS and 20 HbSC patients and in race-matched HbAA controls. NOAC levels were reduced in patients, and endothelial activation markers and hsCRP were elevated (except vWF in HbSC patients). Protein C activity and vWF levels were lower in HbSC patients who experienced painful crises compared to HbSC patients who were clinically asymptomatic. No other differences were observed between patients who did and did not experience vaso-occlusive events (painful crises, stroke, acute chest syndromes) or leg ulcers. A significant positive correlation between total protein S with hemoglobin levels and a significant negative correlation between total and free protein S and sVCAM-1 were detected in HbSS patients. Except perhaps for protein C in relation to painful crises in HbSC patients, these markers were not associated with the occurrence of clinical events. The protein S, hemoglobin, and sVCAM-1 associations may suggest decreased endothelial protein S production due to the more severe endothelial perturbation in HbSS patients with lower hemoglobin levels.

[Kidney transplant program facilitated by airlift between the Netherlands Antilles and the Netherlands; 1998-2001]

OBJECTIVE

To describe the results of a structured kidney-transplantation programme available to dialysis patients in Curaçao (Dutch Caribbean), involving transplantation in the Netherlands and follow-up in Curaçao.

DESIGN

Descriptive.

METHOD

In 1998, a joint venture was begun with the Academic Medical Center (AMC) in Amsterdam, the Eurotransplant Foundation, the Dutch Transplantation Working Party and the Diagnostic Division of the Sanquin Foundation in Amsterdam, the Netherlands. Its aim was to achieve a structural kidney transplantation programme for patients in the Dutch Caribbean in general and patients in Curaçao in particular. An airlift programme between Curaçao and the AMC was instituted.

RESULTS

Between 1998-2001 19 patients underwent a kidney transplant, three of which failed. In most of the transplants the cold ischaemia time was less than 48 hours; the average cold ischaemia time was 32 hours. All patients returned to the Antilles within 3 months where their treatment was continued. Post-transplantation follow-up was on average 13.9 months (limits 3-36); three patients died.

Erythropoiesis and serum sVCAM-1 levels in adults with sickle cell disease

Sickle cell patients are characterized by stress erythropoiesis involving cytokines, growth factors, and adhesion molecules. We set out to determine whether serum soluble vascular cell adhesion molecule-1 (sVCAM-1) levels, which are inversely related to red blood cell counts in sickle cell disease (SCD), reflect erythropoietic activity in adult HbSS patients. Serum levels of sVCAM-1 were compared to erythropoietin (EPO), granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3), and soluble transferrin receptor (sTfR) levels in 29 adults with HbSS, and their respective levels were also compared to 29 race- and age-matched HbAA controls. EPO and sTfR levels were increased as compared to healthy controls, whereas IL-3 and GM-CSF were not. No significant correlation of sVCAM-1 levels could be detected with any of the measured erythropoietic markers. Patients, but not controls, with detectable IL-3 levels had lower sTfR and GM-CSF levels as compared to patients with undetectable IL-3 levels. Even though a link of sVCAM-1 to erythropoiesis could not be established, it cannot be ruled out that sVCAM-1 levels reflect the release of young red blood cells into the circulation. IL-3 and GM-CSF levels suggest that different rates of erythropoiesis may be characterized by specific cytokine profiles in SCD. Further research should focus on the potential cytokines and adhesion molecules involved in sickle cell erythropoiesis, as this may increase our understanding of sickle cell complications and may provide us with potential markers for risk assessment in sickle cell disease as well.

Steady-state sVCAM-1 serum levels in adults with sickle cell disease

Cytokines and adhesion molecules play an important role in the pathophysiology of vaso-occlusion in sickle cell disease (SCD), and their in vivo profiles are potential tools for assessing SCD severity. We compared steady-state soluble vascular cell adhesion molecule-1 (sVCAM-1) serum levels to clinical (painful crisis frequency, occurrence of acute chest syndrome, leg ulcers, and cerebrovascular disease) and related hematological parameters of SCD severity (such as HbF%, hemoglobin levels, and leukocyte counts) in 29 HbSS adults. Serum sVCAM-1 levels were not related to clinical severity, but an inverse correlation was demonstrated between sVCAM-1 and hemoglobin levels (r=-0.71, p<0.001) with a positive correlation to serum lactate dehydrogenase levels (r=0.59, p=0.008). Based upon these results, steady-state serum sVCAM-1 levels do not seem to reflect clinical disease severity. However, as VCAM-1 is involved in hematopoiesis, sVCAM-1 levels might reflect bone marrow activity in SCD. This underlies the pleiotropic nature of adhesion molecules in vivo and the need for further research in this area, especially since therapies targeting (cellular) adhesive interactions involving the endothelium are emerging for SCD.

No effect of acenocoumarol therapy on levels of endothelial activation markers in sickle cell disease

Sickle cell patients are characterized by a chronic inflammatory and hypercoagulable state, depicted by elevated levels of pro-inflammatory cytokines, endothelial adhesion molecules, and elevated markers of thrombin generation. We set out to determine whether anticoagulation with a coumadin derivative reduces inflammation in sickle cell disease. Therefore, serum levels of NFkappaB-regulated endothelial adhesion molecule soluble vascular cell adhesion molecule-1 and serum levels of non-NFkappaB-dependent markers of endothelial activation (soluble cellular fibronectin and von Willebrand factor antigen) were compared during treatment with acenocoumarol (INR 1.6-2.0) and placebo. No effect on circulating levels of the measured parameters was observed during treatment with acenocoumarol as compared to placebo. In the targeted INR range, anticoagulation of sickle cell patients with acenocoumarol does not seem to reduce endothelial activation.

Low adjusted-dose acenocoumarol therapy in sickle cell disease: a pilot study

Vasoocclusion is a continuous process in sickle cell disease (SCD) and accumulates to significant end organ damage, mostly irrespective of the occurrence of manifest acute vasoocclusive events. As there are indications that reversing the hypercoagulable state may be of clinical benefit in sickle cell patients, we performed a randomized, double blind, placebo-controlled, cross-over pilot study to assess the efficacy and safety of low-adjusted dose acenocoumarol therapy (International Normalized Ratio: 1.6-2.0) in SCD. Treatment consisted of either acenocoumarol or placebo for 14 weeks, after which treatment was discontinued for a period of five weeks. Then, patients initially on acenocoumarol received placebo (and vice versa) for 14 weeks. Therapy efficacy was assessed by comparing the frequency of vasoocclusive complications, the occurrence of bleeding, and clotting activation between acenocoumarol and placebo treatment of each individual patient. Twenty-two patients (14 homozygous [HbSS] and 8 double heterozygous sickle-C [HbSC]; aged 20-59 years) completed the entire study. Acenocoumarol treatment did not result in a significant reduction of acute vasoocclusive events (three painful crises during acenocoumarol, five painful crises during placebo). There was a marked reduction of the hypercoagulable state (depicted by a decrease in plasma levels of prothrombin F1.2 fragments [P = 0.002], thrombin-antithrombin complexes [P = 0.003], and D-dimer fragments [P = 0.001]) without the occurrence of major bleeding. Even though no clinical benefit (pertaining to the frequency of painful crises) was detected in this pilot study, the value of low adjusted-dose acenocoumarol for preventing specific events (such as strokes) and as a long-term treatment of sickle cell patients should be subject of further study.

Duffy phenotype does not influence the clinical severity of sickle cell disease

The red blood cell Duffy antigen receptor for chemokines serves as a sink for the clearance of chemokines such as interleukin-8 (IL-8) from the circulation. We analyzed the impact of the Duffy phenotype on sickle cell disease (SCD) severity and serum IL-8 levels in 15 Duffy-positive and 36 Duffy-negative sickle cell patients. There was no difference in clinical severity between Duffy-positive and Duffy-negative sickle cell patients. In asymptomatic sickle cell patients the upward deviation of mean serum IL-8 levels was significantly greater in Duffy-negatives (n = 20) than in Duffy-positives (n = 8) (P = 0.011). However, during a vasoocclusive episode, serum IL-8 levels were similar between Duffy-negatives (n = 11) and Duffy-positives (n = 3). Although the Duffy phenotype seems to influence steady-state serum IL-8 levels, it does not seem to have an effect on SCD severity.

Cytokines and soluble adhesion molecules in sickle cell anemia patients during hydroxyurea therapy

Hydroxyurea (HU) induces HbF production and can reduce painful crises in some patients with sickle cell anemia (SS). However, HbF induction alone cannot explain the beneficial effect of HU treatment as some patients experience clinical improvement while showing only minor increases in HbF. Other actions of HU, in particular its effects on vascular endothelium, adhesion molecule expression and cytokine production may also play a role in the final therapeutic outcome. In order to analyze these effects we studied the levels of interleukin-3 (IL-3), interleukin-6, granulocyte-macrophage colony-stimulating factor, erythropoietin, stem cell factor, soluble vascular adhesion molecule-1, soluble intercellular adhesion molecule-1, soluble E-selectin and soluble P-selectin in 7 SS patients before and during 5 months of HU treatment. Use of HU seems to have no detectable effect on soluble adhesion molecules, but the steady state levels of soluble vascular adhesion molecule-1 are enhanced in SS patients compared to normal controls. Of the cytokines studied, only IL-3 showed an increase during therapy, suggesting HU may induce early erythroid progenitors capable of producing HbF by a direct or indirect effect on IL-3 production. Remarkably, the steady state stem cell factor levels in sickle cell patients seemed to be decreased compared to healthy controls.

Two common endoglin mutations in families with hereditary hemorrhagic telangiectasia in the Netherlands Antilles: evidence for a founder effect

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant bleeding disorder characterized by localized angiodysplasia. Mutations in either of two genes, endoglin or ALK-1, can cause HHT. Both genes encode putative receptors for the transforming growth factor-beta superfamily of ligands. Many mutations in each gene have been identified in HHT kindreds from around the world, and with few exceptions mutations are unique and family specific. The prevalence of HHT in the Leeward Islands of the Netherlands Antilles is possibly the highest of any geographical location. We wished to establish whether this high prevalence is due to a genetic founder effect or to multiple mutational events. HHT kindreds from the Netherlands Antilles and The Netherlands were screened for mutations in the two genes associated with HHT. Haplotype analysis of a 5-cM region on chromosome 9 flanking the endoglin gene revealed three distinct disease haplotypes in the ten Antillean families studied. Seven of these families share a splice-site mutation in exon 1 of endoglin. Two other Antillean families share a missense mutation in exon 9a of endoglin. This mutation was also found in a Dutch family that shares the same disease haplotype as the Antillean families with this mutation. Thus it appears that HHT in the Netherlands Antilles is due to a limited number of ancestral mutations in the endoglin gene, and that one of these mutations was introduced into the African slave population by a Dutch colonist. The limited scope of mutations suggests that a presymptomatic screening program for HHT would be feasible in this population.

Selective deficit of angiogenic growth factors characterises pregnancies complicated by pre-eclampsia

OBJECTIVE

To compare serum levels of angiogenic growth factors vascular endothelial growth factor (VEGF), placental growth factor (PlGF) and angiogenin in pre-eclamptic women and matched controls.

DESIGN

Retrospective analysis of -70 degrees C stored serum of women who developed pre-eclampsia and matched controls.

SETTING

Department of Gynaecology and Obstetrics, St Elisabeth Hospital, Curaçao, Netherlands Antilles.

SAMPLE

Thirty women with pre-eclampsia and 30 normotensive controls matched for age and gestation.

RESULTS

VEGF and PIGF serum levels were significantly lower in pre-eclamptic pregnancies, compared with controls (VEGF 0.31 +/- 1.20 vs 18.30 +/- 24.97 pg/mL, P = 0.0004; PlGF 54.19 +/- 32.05 vs 497.95 +/- 340.51 pg/mL, P < 0.0001). Matched couple analysis showed VEGF serum concentrations to be lower in the majority of pre-eclamptic women and PlGF concentrations to be lower in all pre-eclamptic women. Angiogenin serum levels showed no statistical significant difference between pre-eclamptic pregnancies and controls (523.68 +/- 367.55 vs 670.41 +/- 251.54 ng/mL, P = 0.058), with matched couple analysis showing no clear pattern.

CONCLUSIONS

Decreased serum levels of VEGF and PIGF characterise, and therefore seem to be of importance during (the development of), pre-eclampsia. This selective deficit of angiogenic growth factors might in part explain the shallow placentation found in this pregnancy complication.

Levels of endothelial, neutrophil and platelet-specific factors in sickle cell anemia patients during hydroxyurea therapy

It has been shown that the clinical course of sickle cell (SS) patients can be ameliorated by administration of hydroxyurea (HU). Induction of hemoglobin F (HbF) is thought to be the mechanism responsible for clinical improvement in some patients. However, HU has a variable effect on HbF production and there exists no good correlation between the extent of HbF increase and clinical response. On the other hand, the degree of adherence of SS to vascular endothelium and neutrophil counts correlate well with clinical severity. Being a cytotoxic drug, used in myeloproliferative diseases, HU may alter proliferation among various cell lines. Moreover, HU has been reported to reduce red blood cell (RBC) adhesion receptor expression in young SS individuals and induces changes in endothelial cells in vitro. It should be conceived that in addition to its effects on HbF production, HU may change the clinical symptoms of SS patients by affecting the degree of adherence of different blood cells, by influencing the activity of endothelium as well as the activity of white blood cells (WBC) and platelets. To analyze whether several of the determinants of adhesion are modulated by HU treatment we studied the levels of endothelial activity (soluble vascular adhesion molecule-1, (sVCAM-1), interleukin-8 (IL-8), fibronectin, neutrophil activity (sL-selectin, sIL-6 receptor-alpha, myeloperoxidase) and platelet activity (von Willebrand factor) in relation to clinical symptoms, hematological data and HbF levels in 8 SS patients before and during 5 months of HU therapy. Steady state sVCAM-1 levels are increased compared to normal controls and a significant decrease is noted during HU treatment, suggesting a decrease in the interactions between RBC and vascular endothelium. The IL-8 levels are comparable to those in normal controls and remain unaffected by HU therapy. Intercurrent infection and crises reveal striking increases in IL-8 which are accompanied by leukocytosis, but otherwise the IL-8 levels do not correlate with hematological data. HU has no demonstrable effect on fibronectin or soluble neutrophil adhesion molecules, but the levels of myeloperoxidase decrease significantly while WBC counts do not, implying a reduction in neutrophil activity which may help attenuate the propagation phase of a vasoocclusive crisis.

Neutrophil activation in sickle cell disease

Vascular occlusion is the main cause of the morbidity and mortality observed in patients with sickle cell disease (SCD). Increasing evidence indicates that (activated) neutrophils could play an important role in the initiation and propagation of vaso-occlusive processes in SCD. In this study, the activation state of neutrophils in sickle cell patients was analyzed by determining the level of expression of neutrophil antigens such as CD62L, CD11b, CD66b, CD63, and Fcgamma receptors. We also analyzed plasma levels of lactoferrin, elastase, soluble (s)CD16 (sFcgammaRIII), and serum levels of soluble (s)CD62L (sL-selectin) as neutrophil activation markers in these patients. Significant differences were observed in the activation state of neutrophils in non-symptomatic sickle cell patients compared to healthy HbAA controls as exemplified by significant decrease in L-selectin expression, enhanced expression of CD64, and increased levels of soluble markers like sL-selectin, elastase, and sCD16. During vaso-occlusive crisis the differences were even more pronounced. These results show neutrophils to be activated in sickle cell patients, suggesting a role of importance in the pathophysiology of sickle cell disease.

Elevated homocysteine levels indicate suboptimal folate status in pediatric sickle cell patients

We investigated whether pediatric patients with sickle cell disease (SCD) (9 +/- 4 years; 27 homozygous SCD [HbSS]; 19 sickle-C disease [HbSC]) have different folate status compared with age-, sex-, and race-matched normal hemoglobin (HbAA) controls (n = 20), and whether their folate status can be improved by folate supplementation. The patients were supplemented with vitamins B6 and B12 during one week and with folate during the following week. Circulating folate, homocysteine, vitamin B6 and vitamin B12 levels were measured at baseline (patients and controls), after one week and after two weeks (patients). The patients had similar folate, vitamin B6, and vitamin B12, but higher homocysteine levels compared with HbAA controls (12.7 +/- 4.5 vs. 10.9 +/- 3.5 micromol/l; P = 0.04). Vitamin B6 and B12 supplementation did not change their homocysteine levels, but folate supplementation caused a 53% reduction (to 5.7 +/- 1.6). We conclude that patients with SCD have adequate vitamin B6 and B12 status, but suboptimal folate status, leading to elevated plasma homocysteine levels. They may therefore benefit from folate supplementation to reduce their high risk for endothelial damage.

Elevated IL-8 levels during sickle cell crisis

The vaso-occlusive process (VOC) in sickle cell disease is of a complex nature. It involves intricate interactions between sickle red blood cells, endothelium and probably also leukocytes. As these interactions are regulated by cytokines, we analyzed the role of the potent neutrophil chemokine IL-8 by measuring serum levels in sickle cell patients during sickle cell crisis. These results were compared to nonsymptomatics and healthy controls. In patients having a vaso-occlusive crisis both HbSS and HbSC patients showed significantly enhanced serum IL-8 levels compared to healthy controls. Several of these patients showed extremely elevated serum IL-8 levels which were independent of the crisis inducing factor. Furthermore, a sickle cell patient with VOC as a complication of rhGM-CSF treatment similarly showed high IL-8 serum levels at crisis onset. Nonsymptomatic sickle cell patients serum IL-8 levels were comparable to healthy controls. These results implicate a role for IL-8 at or during (the initiation of) sickle cell crisis.

New concepts in assessing sickle cell disease severity

Vasoocclusion leads to pain, chronic organ damage, and a decreased life expectancy in patients with sickle cell disease. Therapeutic options for sickle cell disease have usually been evaluated according to their capacity for reducing the frequency of vasoocclusive crises requiring clinical attention. However, the frequency of vasoocclusive crises is not representative for the rate of accumulating organ damage in most sickle cell patients. This implies that the frequency of vasoocclusive crises needn't correlate with disease severity and, although being of importance, cannot solely serve as a parameter of treatment efficacy. Therefore, additional new objective parameters are needed to effectively study the vasoocclusive process in sickle cell disease. Several studies show that intricate adhesive interactions between (red) blood cells, plasma components, and endothelium play a crucial role in the pathophysiology of sickle cell vasoocclusion, offering new potential parameters to effectively assess disease severity as well as new therapeutical targets in the near future. Whether these adhesive mechanisms involve the causes or the effects of vasoocclusion will be determined if their inhibition, by interventive measures, results in therapeutic benefits.

Enhanced levels of soluble VCAM-1 in sickle cell patients and their specific increment during vasoocclusive crisis

Adhesion of sickle erythrocytes to vascular endothelium plays a central role in sickle cell disease complications. Cytokines and adhesion molecules are critically involved in the regulation of these adhesive processes. To analyze their role, IL-6, GM-CSF, sVCAM-1, sICAM-1, sE-Selectin, and sP-Selectin serum levels were determined in sickle cell patients under basic conditions and during vasoocclusive crisis. In nonsymptomatic patients a high serum level of sVCAM-1 was observed compared to controls. In patients having vasoocclusive crisis sVCAM-1 levels increased even more and seemed to correlate with crisis evolution.

Skewed distribution of IgG Fc receptor IIa (CD32) polymorphism is associated with renal disease in systemic lupus erythematosus patients

OBJECTIVE

Fc gamma receptors of class IIa (Fc gamma RIIa) occur in 2 allelic forms, with either a low (IIa-R131) or a high (IIa-H131) affinity for complexed IgG2 and IgG3. This polymorphism might have implications for the handling of immune complexes. Therefore, we determined the distribution of the Fc gamma RIIa allotypes in patients with systemic lupus erythematosus (SLE), with or without a history of lupus nephritis.

METHODS

We studied 95 unrelated white European patients with SLE, as defined by the American College of Rheumatology criteria, 50 of whom had a history of lupus nephritis, and 69 healthy white European control subjects. Fc gamma RIIa allotypes were determined by immunophenotyping of blood monocytes.

RESULTS

It was found that lupus nephritis was significantly associated with the "low affinity" Fc gamma RIIa R/R131 allotype and with the R131 allele, compared with healthy controls. No significant association was found upon comparison of groups with and without nephritis.

CONCLUSION

SLE patients with a history of lupus nephritis have an abnormal distribution of Fc gamma RIIa allotypes. Fc gamma RIIa may well play a role in the pathogenesis of lupus nephritis, since IIa-R/R131 SLE patients seem to have a higher incidence of developing this complication.

CD8 T cell activation after intravenous administration of CD3 x CD19 bispecific antibody in patients with non-Hodgkin lymphoma

A bispecific antibody directed to T and B cells (CD3 x CD19 bsAb) was daily infused intravenously in escalating doses from 10 micrograms up to 5 mg in three patients with chemotherapy-resistant non-Hodgkin lymphoma; in this way we aimed to activate T cells to kill the malignant B cells. Only limited toxicity was observed, consisting of moderate fever preceded by chills or shivers and mild thrombocytopenia. No human anti-(mouse Ig) antibodies were found. Pharmacokinetics showed a t1/2 of 10.5 h with peak levels of 200-300 ng/ml after infusion of 2.5 mg bsAb. bsAb in serum was functionally active in vitro. After bsAb infusion a rise in serum tumour necrosis factor alpha was observed, accompanied by an increase in soluble CD8 and to some extent in soluble interleukin-2 receptor (IL-2R), but not in interferon gamma. IL-4 or soluble CD4. No evidence was found for monocyte activation (no increases in IL-6, IL-8 or IL-1 beta in serum). No gross changes in histology or number of IL-2R+, CD4+ or CD8+ cells were found in the lymph nodes after therapy, but one patient showed activated CD8+ T cells within the tumour nodules. In conclusion, after intravenously administered CD3 x CD19 bsAb only moderate toxicity was found, probably due to CD8+ T cell activation and cytokine release, without CD4+ T cell activation.

Antisense oligonucleotides, a novel tool for the control of cytokine effects on human cartilage. Focus on interleukins 1 and 6 and proteoglycan synthesis

OBJECTIVE

To prevent the negative effects of interleukin-1 (IL-1) and IL-1-induced IL-6 on cartilage proteoglycan (PG) synthesis, we used an antisense oligonucleotide (ASO) specific for IL-6 messenger RNA (mRNA) to inhibit IL-6 production.

METHODS

Explants of human articular cartilage were cultured in the presence or absence of IL-6-ASO, IL-1, and exogenous IL-6. As metabolic parameters, cartilage production of IL-6 was determined in the B9 bioassay and PG as incorporation of 35SO4.

RESULTS

The IL-6-ASO prevented IL-1-induced production of IL-6 in the cartilage explants, as well as IL-1-induced inhibition of PG synthesis. This inhibition was restored, despite the presence of IL-6-ASO, when exogenous IL-6 was added. A control ASO (not specific for IL-6 mRNA) was not effective.

CONCLUSION

The IL-6-ASO used can penetrate the extracellular matrix of articular cartilage, enter the chondrocytes, and inhibit the IL-1-induced production of IL-6. Furthermore, IL-6-ASO can prevent the IL-1-induced inhibition of cartilage PG synthesis. The effect of exogenous IL-6 shows that IL-1 requires IL-6 for inhibition of PG synthesis.

Leukocyte adhesion deficiency in a Dutch Holstein calf: a case with a clear-cut family history

A leukocyte adhesion deficiency characterized by recurrent (predominantly bacterial) infections, lack of extravascular polymorphonuclear leukocyte (PMN) and pus formation has been described first in humans and then in dogs, and recently also in cattle. Because of important clinical similarities, a unitary explanation for the leukocyte adhesion deficiency (LAD) syndrome in mammals is proposed, inasmuch that an intrinsic leukocyte defect (i.e. mutations in genes encoding the common CD18 subunit), is thought to cause the disease. However, thus far, the hallmark of such intrinsic leukocyte defects, notably their heritability (or familial incidence), has not (yet) been unequivocally demonstrated. This is the first report to describe the occurrence of four Dutch bovine LAD (BLAD) cases with the clearest familial clustering observed to date. The diagnosis was based on the clinical features of very poor thriving, in general, of the calves, hyperneutrocytosis without appreciable left shift, and the absence of PMN CD11a, or CD11b, or CD11c using monoclonal antibodies (mAb) and/or Concanavalin A binding activity of PMN lysates in immunoblots. Interestingly, a familial clustering was observed also for below-normal PMN CD11c expression. Thus, a cow with low CD11c expression (50.4%) and delivering three of the study BLAD calves, also had a healthy descendant with low (44.9%) PMN CD11c expression. These findings suggested the possibility that both subnormal expression and lack of PMN CD11 expression are inheritable factors in cattle. Furthermore, a large prospective study using the present mAb for selecting relatives expressing the complete spectrum (0 to > or = 90%) of PMN CD11/CD18 expression would create a comprehensive study population for understanding both the role of genetic factors and of survival strategies in BLAD.

Elevated synovial fluid levels of interleukin-6 and tumor necrosis factor associated with early experimental canine osteoarthritis

OBJECTIVE

To measure levels of cytokines, proteases, and glycosaminoglycans (GAG) in synovial fluid (SF) from the knees of animals with experimental osteoarthritis (OA) and from their contralateral (control) knees, and to compare and correlate these values with each other as well as with measures of proteoglycan synthesis in the corresponding articular cartilage. This study will help to identify cytokines of potential importance in the early stages of the development of OA.

METHODS

OA was induced in 12 mature animals by sectioning the anterior cruciate ligament. After 3 months, SF from the operated and contralateral (control) knee joints was assayed for interleukin-6 (IL-6), tumor necrosis factor (TNF), IL-1, latent metalloproteinase, and sulfated GAG. Proteoglycan synthesis in the corresponding articular cartilage was also measured.

RESULTS

IL-6 levels in SF from the operated joint compared with the control joint were significantly elevated in 11 of 12 animals. TNF levels were also elevated in 10 of 11 SF samples from operated joints, but to a lesser extent than those of IL-6. IL-1 and IL-1 inhibitors were undetectable in either the operated or control joint SF. The GAG concentration was elevated in SF from experimental OA joints. This elevation correlated with that of TNF, but not IL-6. There was no significant difference in the concentration of APMA-activatable metalloproteinase. The rate of proteoglycan synthesis was higher in the cartilage from the operated joint in 8 of 12 animals, and the mean rate of synthesis was significantly higher than in the control joint. There was a positive correlation between this increase in cartilage proteoglycan synthesis (operated versus control) and the increase in SF IL-6, but there was no correlation with the levels of TNF or GAG.

CONCLUSION

This is the first study of SF levels of cytokines in early experimental OA. Our results show surprisingly high levels of IL-6 in operated joints, where the cytokine could act directly on the chondrocytes, and thus play a role in mediating their responses to cartilage injury.

Isotype-specific cross-linking of select human Fc gamma R isoforms triggers release of IL-6

Anti-CD3 MoAbs are widely used in T cell activation studies, and are effective in immunosuppressive therapy. We used a panel of mouse (m) anti-CD3 switch variant MoAbs of five different isotypes to study IL-6 release from accessory cells. Incubation of human (h) mononuclear cells with anti-CD3 MoAbs resulted in increased IL-6 levels with MoAbs of mIgG1 and mIgG2a isotypes, with no effect of mIgG2b or mIgA. This suggested involvement of IgG Fc receptors (Fc gamma R) in triggering IL-6 production. To evaluate the role of different Fc gamma R molecules individually we used a panel of hFc gamma R-transfected mouse fibroblasts, and Jurkat T cells as a model. IL-6 secretion by CD32 transfectants expressing the hFc gamma RIIa high-responder (HR) allelic form was triggered by mIgG1 anti-CD3 MoAb, with no effect of four other isotypes. None of the anti-CD3 MoAbs induced IL-6 secretion by CD32 transfectants expressing either a variant of this receptor, containing only a single intracellular amino acid (CT-), the hFc gamma RIIa low-responder (LR) allelic form, or hFc gamma RIIb1. hFc gamma RI (CD64) transfectants exhibited IL-6 production after incubation with mIgG2a anti-CD3 MoAb, and to a lesser extent with mIgG2b, and mIgG1 MoAb. Indirect involvement of T cells in triggering IL-6 secretion could be excluded by experiments in which transfectants were cultured with immobilized anti-CD3 MoAb. These data indicate that cross-linking of either hFc gamma RI, or hFc gamma RIIaHR by appropriate anti-CD3 MoAbs triggers IL-6 production of accessory cells, and not T cells. This may also take place in vivo during immunosuppressive therapy with anti-CD3 MoAbs, and related antibody-mediated immune responses.

Immunoadjuvant activity of a liposomal IL-6 formulation

The adjuvant effect of interleukin 6 (IL-6) entrapped in liposomes was evaluated using a 65 kDa heat shock protein as a model antigen. The secondary humoral immune response either to antigen alone, or incorporated into liposomes, and the effect of IL-6 entrapped in liposomes, on this response were studied in Balb/c mice. The adjuvanticity of these formulations was compared with that of potent adjuvants such as Ribi and dimethyldioctadecylammoniumbromide (DDA). The importance of IL-6 during adjuvant activity was supported by the observation that high serum IL-6 levels were induced in Balb/c mice by all members of a panel of adjuvants tested. Following incorporation into liposomes, IL-6 retained its full biological activity, as shown by its capacity to sustain growth of the IL-6-dependent B9 cell line. At antigen dosages where Ribi and DDA gave minimal or no secondary antibody titres, incorporation of antigen into liposomes resulted in measurable secondary antibody titres. Interestingly, this adjuvant activity was significantly enhanced when liposomes containing IL-6 were co-injected with the liposomal antigen formulation. These results illustrate the potential adjuvant properties of this formulation, which seem especially useful for vaccines containing weak or non-immunogenic antigens.

Synergism of interleukin 6 and 1α,25-dihydroxyvitamin D3 in induction of myeloid differentiation of human leukemic cell lines

Interleukin 6 (IL-6) is a multifunctional cytokine with an important role in immunity. We analyzed the effect of recombinant human IL-6 in combination with 1 alpha,25-dihydroxyvitamin D3 (Vit. D3) on differentiation of the human myeloid leukemic cell lines U937 and HL-60 with respect to alterations in antigen expression and functional activity. Of a panel of antigens analyzed, only CD11b (the alpha chain of CR3), and CD14 (a cell surface protein recognizing the lipopolysaccharide-binding protein-lipopolysaccharide complex) had significantly increased expression. Expression of ICAM-1 (CD54), a ligand for LFA-1, was also found to be enhanced with a concomitant increase of ICAM-1 mRNA levels. Enhanced nonspecific esterase levels and induction of respiratory burst activity confirmed that cell differentiation was induced. Furthermore, IL-6 and Vit. D3 had a profound effect on functional activities, as shown by enhancement of rosetting between sheep erythrocytes, sensitized with C3bi (EAC), and either U937 or HL-60 cells. Also, phorbol myristate acetate-induced homotypic adhesion of U937, which is ICAM-1 dependent, was markedly induced by these agents. These results indicate an important role of IL-6 and Vit. D3 in myeloid cell function and development.

Selective enhancement of Leu-CAM expression by interleukin 6 during differentiation of human promonocytic U937 cells

Interleukin 6 (IL-6) is a cytokine with multiple biological activities on various tissues and cells. We have investigated the effect of recombinant human IL-6 (rhIL-6) on growth and differentiation of U937. Recombinant human IL-6 induced a dose-dependent growth inhibition, apparent around day 4, of up to 50% by day 8 of culture. Concomitant with this, changes in cytochemical activities were observed, indicative of differentiation. A panel of U937 antigens was analysed after culture with rhIL-6. Expression of the majority of these membrane antigens was unaffected, with the exception of two classes. First, rhIL-6 had a profound effect on members of the leucocytic cell adhesion molecules (Leu-CAM) family. Expression of the alpha-chain of CR3 (complement receptor 3; CD11b) was enhanced in a dose-dependent fashion, with maximal expression around day 7. Parallel to this a simultaneous increase in beta-chain (CD18) expression was found. Furthermore, enhanced expression of CR3 was, accompanied by increased rosetting with sheep erythrocytes sensitized with C3bi. A much lower, but significant, enhancement was observed for the alpha-chain of the p150,95 antigen (CD11c). Expression of leucocyte function-associated antigen-1, (LFA-1), (CD11a/CD18) remained unchanged. Remarkably, however, expression of a ligand of LFA-1, intercellular adhesion molecule-1 (ICAM-1; CD54), was enhanced with similar kinetics as CR3 and p150,95. A specific anti-rhIL-6 antiserum completely inhibited the IL-6 effect. These observations provide further support for an important role of IL-6 in the regulation of myeloid cell development in man.

Differential expression of the gene encoding the novel pituitary polypeptide 7B2 in human lung cancer cells

The protein designated 7B2 is a recently discovered pituitary polypeptide which is selectively expressed in cells containing secretory granules, such as neurons and endocrine cells. Northern blot analysis of 7B2 gene expression in small cell lung carcinoma (SCLC) cell lines revealed that 7B2 was expressed in all nine cell lines of the classic type tested, but in six of seven SCLC cell lines of the variant type, 7B2 expression could not be detected. In only one of four non-SCLC cell lines tested, 7B2 was expressed. Furthermore, in 16 primary human non-SCLCs, no or only very low expression of 7B2 was found. In the eight primary human SCLCs tested, expression of 7B2 appeared variable: three exhibited a high level of expression; three a low level; while in two cases, expression was very low or not detectable at all. Finally, the three carcinoid tumors tested expressed very high levels of 7B2 mRNA. These data indicate that the 7B2 gene is a useful marker not only to discriminate between classic and variant types of SCLC cell lines, but also in human lung cancer diagnosis.