Comparative effectiveness and cost-effectiveness of natalizumab and fingolimod in rapidly evolving severe relapsing-remitting multiple sclerosis in the United Kingdom.

AIM: To evaluate the real-world comparative effectiveness and the cost-effectiveness, from a UK National Health Service perspective, of natalizumab versus fingolimod in patients with rapidly evolving severe relapsing-remitting multiple sclerosis (RES-RRMS). METHODS: Real-world data from the MSBase Registry were obtained for patients with RES-RRMS who were previously either naive to disease-modifying therapies or had been treated with interferon-based therapies, glatiramer acetate, dimethyl fumarate, or teriflunomide (collectively known as BRACETD). Matched cohorts were selected by 3-way multinomial propensity score matching, and the annualized relapse rate (ARR) and 6-month-confirmed disability worsening (CDW6M) and improvement (CDI6M) were compared between treatment groups. Comparative effectiveness results were used in a cost-effectiveness model comparing natalizumab and fingolimod, using an established Markov structure over a lifetime horizon with health states based on the Expanded Disability Status Scale. Additional model data sources included the UK MS Survey 2015, published literature, and publicly available sources. RESULTS: In the comparative effectiveness analysis, we found a significantly lower ARR for patients starting natalizumab compared with fingolimod (rate ratio [RR] = 0.65; 95% confidence interval [CI], 0.57-0.73) or BRACETD (RR = 0.46; 95% CI, 0.42-0.53). Similarly, CDI6M was higher for patients starting natalizumab compared with fingolimod (hazard ratio [HR] = 1.25; 95% CI, 1.01-1.55) and BRACETD (HR = 1.46; 95% CI, 1.16-1.85). In patients starting fingolimod, we found a lower ARR (RR = 0.72; 95% CI, 0.65-0.80) compared with starting BRACETD, but no difference in CDI6M (HR = 1.17; 95% CI, 0.91-1.50). Differences in CDW6M were not found between the treatment groups. In the base-case cost-effectiveness analysis, natalizumab dominated fingolimod (0.302 higher quality-adjusted life-years [QALYs] and £17,141 lower predicted lifetime costs). Similar cost-effectiveness results were observed across sensitivity analyses. CONCLUSIONS: This MSBase Registry analysis suggests that natalizumab improves clinical outcomes when compared with fingolimod, which translates to higher QALYs and lower costs in UK patients with RES-RRMS.

There are several medications used to treat people with relapsing remitting multiple sclerosis, such as interferon-based therapies (Betaferon/Betaseron (US), Rebif, Avonex, Extavia), glatiramer acetate (Copaxone), teriflunomide (Aubagio), and dimethyl fumarate (Tecfidera), collectively named BRACETD. Other treatments for multiple sclerosis (MS) have a narrower use, such as natalizumab (Tysabri) or fingolimod (Gilenya), among others.This study objective was to assess how well natalizumab and fingolimod helped treating MS (clinical effectiveness) and subsequently estimate what the cost of these treatments is in comparison to the benefit they bring to people with rapidly evolving severe MS that use them in the United Kingdom (UK) (cost-effectiveness).We used an international disease registry (MSBase), which collects clinical data from people with MS in various centers around the world to compare the effectiveness of natalizumab, fingolimod and BRACETD treatments. We used a technique called propensity score matching to obtain results from comparable patient groups. People treated with natalizumab had better disease control, namely with fewer relapses and higher improvement on their disability level, than patients on fingolimod or BRACETD. Conversely, there were no differences between each group of people on a measure called disability worsening.Based on these clinical results, we built an economic model that simulates the lifetime costs and consequences of treating people with MS with natalizumab in comparison with fingolimod. We found that using natalizumab was less costly and was more effective compared to using fingolimod in UK patients.

Pembrolizumab versus cetuximab concurrent with radiotherapy in patients with locally advanced squamous cell carcinoma of head and neck unfit for cisplatin (GORTEC 2015-01 PembroRad): a multicenter, randomized, phase II trial.

BACKGROUND: To evaluate potential synergistic effect of pembrolizumab with radiotherapy (RT) compared with a standard-of-care (SOC) cetuximab-RT in patients with locally advanced-squamous cell carcinoma of head and neck (LA-SCCHN). PATIENTS AND METHODS: Patients with nonoperated stage III-IV SCC of oral cavity, oropharynx, hypopharynx, and larynx and unfit for receiving high-dose cisplatin were enrolled. Patients received once-daily RT up to 69.96 Gy in 33 fractions with weekly cetuximab (cetuximab-RT arm) or 200 mg Q3W pembrolizumab during RT (pembrolizumab-RT arm). The primary endpoint was locoregional control (LRC) rate 15 months after RT. To detect a difference between arms of 60%-80% in 15-month LRC, inclusion of 66 patients per arm was required to achieve a power of at least 0.85 at two-sided significance level of 0.20. RESULTS: Between May 2016 and October 2017, 133 patients were randomized to cetuximab-RT (n = 66) and pembrolizumab-RT (n = 67). Two patients (one in each arm) were not included in the analysis (a consent withdrawal and a progression before treatment start). The median age was 65 years (interquartile range 60-70 years), 92% were smokers, 60% were oropharynx (46% of oropharynx with p16+) and 75% were stage IV. Median follow-up was 25 months in both arms. The 15-month LRC rate was 59% with cetuximab-RT and 60% with pembrolizumab-RT ]odds ratio 1.05, 95% confidence interval (CI) 0.43-2.59; P = 0.91]. There was no significant difference between arms for progression-free survival (hazard ratio 0.85, 95% CI 0.55-1.32; P = 0.47) and for overall survival (hazard ratio 0.83, 95% CI 0.49-1.40; P = 0.49). Toxicity was lower in the pembrolizumab-RT arm than in the cetuximab-RT arm: 74% versus 92% patients with at least one grade ≥3 adverse events (P = 0.006), mainly due to mucositis, radiodermatitis, and rash. CONCLUSION: Compared with the SOC cetuximab-RT, pembrolizumab concomitant with RT did not improve the tumor control and survival but appeared less toxic in unfit patients with LA-SCCHN.

Development of an osteosarcoma following dental extraction after allogeneic stem cell transplantation.

OBJECTIVES: Radio-induced sarcoma is known to occur several years following bone irradiation especially when this treatment is combined to high dose chemotherapy regimens prior to allogeneic haematopoietic stem cell transplantation (HSCT) in very young children. However, little is known about the stimulus of aggressive bony surgery in the development of these tumours. MATERIAL AND METHODS: We report the case of a young girl in whom dental extraction was rapidly followed by the occurrence of a localized tumour 11 years after allogeneic haematopoietic stem cell transplantation using total body irradiation (TBI) for a haemophagocytic lymphophistiocytosis (HLH). RESULTS: This tumour involved tooth socket and all the right side of the mandible and was diagnosed as an osteogenic osteosarcoma of the zygomatic bone. CONCLUSION: This tumour had the characteristics of a radio-induced sarcoma. Thanks to the very short time between the dental extraction and the occurrence of the osteosarcoma at the same location, we discuss the role of the dental extraction as a trigger of osteosarcoma development.

Pronuclear morphology differs between women more than 38 and women less than 30 years of age.

Pronuclear morphology has been reported as a good tool for studying embryo development and euploidy. Comparing two groups of women with different aneuploidy risk, women more than 38 years old (n = 28) known to be at high risk of aneuploidy, and women under 30 years old (n = 35), this study investigated whether pronuclear morphology could be used routinely as an alternative to preimplantation genetic screening (PGS) in countries where PGS is prohibited. Pronuclear morphology was evaluated for 301 zygotes and related to embryo quality and pregnancy outcome. For the older women, an increased frequency of zygotes with abnormal polar body and pronuclei alignment was observed, i.e. type gamma, with 93% aneuploidy risk (26.0 versus 15.1% P < 0.05) and fewer zygotes with a good development prognosis (36.4 versus 47.8%; P < 0.05). A1alpha configuration was associated with good implantation rate and was not related to day 2 embryo quality. This configuration was less frequent in the group of women more than 38 years old and among non-pregnant women under 30 years, compared with pregnant women under 30 years old. Pronuclear morphology seemed linked to age, but not associated with embryo quality. A larger study allowing correlation analysis is necessary to confirm the value of these criteria and the link to a woman's age.

Four-dimensional stereotactic radiotherapy for early stage non-small cell lung cancer: a comparative planning study.

In this study we sought to assess the potential of the respiratory tumor tracking system of the CyberKnife to administer 3 fractions of 15 Gy in the treatment of early stage non-small cell lung cancer (NSCLC). The CyberKnife plans were compared to those developed for 3-D conformal radiotherapy (3-D CRT) administering 20 fractions of 3 Gy based on a slow CT. Ten patients with stage I NSCLC, who were previously treated with 3-D CRT, were re-planned with the CyberKnife treatment planning system. In the 3-D CRT plan, the planning target volume (PTV) included the gross tumor volume (GTV)(slow) and a 15-mm margin, whereas in the CyberKnife plan the margin was 8 mm. The physical doses from both treatment plans were converted to normalized total doses (NTD) using the linear quadratic model with an alpha/beta(tumor) of 10 Gy and alpha/beta(organs at risk (OAR)) of 3 Gy. The average minimal and mean doses administered to the PTV with the CyberKnife and 3-D CRT were 93 and 115.8 Gy and 61 and 66 Gy, respectively (p<0.0001). The mean V(20) of the CyberKnife and 3-D CRT plans were 8.2% and 6.8%, respectively (p=0.124). Both plans complied with the OAR constraints. In conclusion, 4-dimensional stereotactic radiotherapy can increase the minimal and mean biological dose with 51% and 75%, in comparison with 3-D CRT without significantly increasing the V(20), respectively.

Curative stereotactic robotic radiotherapy treatment for extracranial, extrapulmonary, extrahepatic, and extraspinal tumors: technique, early results, and toxicity.

We investigated the technique, early results and toxicity of curative stereotactic radiotherapy with the CyberKnife (Accuray Incorporated, Sunnyvale, California, USA) in 15 extracranial, extrapulmonary, extrahepatic, and extraspinal tumors. Fourteen tumors were located close to the bowel or esophagus. The PTV = GTV + 2-5 mm. The dose to the tumors varied from 10 fractions of 4 Gy up to 3 fractions of 20 Gy (median dose/fraction: 7 Gy; median number of fractions: 6), and depended on the proximity of the bowel. A small volume of the bowel was allowed to receive a dose of 6 Gy/fraction. The dose to the PTV was prescribed to the 75-85% isodose line. With a median follow up of 18 months, the 2-year local control and overall survival was 100%. Due to our flexible fractionation schedules, we were able to prescribe the dose to at least 90% of the PTV (median 95%) without increasing the dose to the bowel > 6 Gy/fraction. Five acute side effects were seen in four patients: two patients had transient grade 1 lymph edema in the leg, one patient complained of grade 1 pain in the abdomen and diarrhea, and one patient complained of grade 1 radiation dermatitis. Late toxicity such as grade 1 rectal bleeding, grade 1 diarrhea, grade 2 painful subcutaneous fibrosis, grade 2 pain in a surgical scar on the abdominal wall and an asymptomatic occlusion of the ureter was observed. Curative stereotactic radiotherapy treatment with the CyberKnife for extracranial, extrapulmonary, extrahepatic, and extraspinal, locally recurrent or solitary metastatic tumors is feasible and results in excellent local control and survival with low acute and late toxicity. A small volume of the bowel is able to tolerate a dose of 6 Gy per fraction for a maximum of 6 fractions.

Robotic radiosurgery vs. brachytherapy as a boost to intensity modulated radiotherapy for tonsillar fossa and soft palate tumors: the clinical and economic impact of an emerging technology.

As a basis for making decisions regarding optimal treatment for patients with tonsillar fossa and soft palate tumors, we conducted a preliminary investigation of costs and quality of life (QoL) for two modalities [brachytherapy (BT) and robotic radiosurgery] used to boost radiation to the primary tumors following external beam radiotherapy. BT was well established in our center; a boost by robotic radiosurgery was begun more recently in patients for whom BT was not technically feasible. Robotic radiosurgery boost treatment has the advantage of being non-invasive and is able to reach tumors in cases where there is deep parapharyngeal tumor extension. A neck dissection was performed for patients with nodal-positive disease. Quality of life (pain and difficulty swallowing) was established in long-term follow-up for patients undergoing BT and over a one-year follow-up in robotic radiosurgery patients. Total hospital costs for both groups were computed. Our results show that efficacy and quality of life at one year are comparable for BT and robotic radiosurgery. Total cost for robotic radiosurgery was found to be less than BT primarily due to the elimination of hospital admission and operating room expenses. Confirmation of robotic radiosurgery treatment efficacy and reduced morbidity in the long term requires further study. Quality of life and cost analyses are critical to Health Technology Assessments (HTA). The present study shows how a preliminary HTA of a new medical technology such as robotic radiosurgery with its typical hypofractionation characteristics might be based on short-term clinical outcomes and assumptions of equivalence.

Lung tumor tracking during stereotactic radiotherapy treatment with the CyberKnife: Marker placement and early results.

Lung tumor tracking during stereotactic radiotherapy with the CyberKnife requires the insertion of markers in or close to the tumor. To reduce the risk of pneumothorax, three methods of marker placement were used: 1) intravascular coil placement, 2) percutaneous intrathoracal, and 3) percutaneous extrathoracal placement. We investigated the toxicity of marker placement and the tumor response of the lung tumor tracking treatment. Markers were placed in 20 patients with 22 tumors: 13 patients received a curative treatment, seven a palliative. The median Charlson Comorbidity Score was 4 (range: 1-8). Platinum fiducials and intravascular embolisation coils were used as markers. In total, 78 markers were placed: 34 intrathoracal, 23 intravascular and 21 extrathoracal. The PTV equaled the GTV + 5 mm. A median dose of 45 Gy (range: 30-60 Gy, in 3 fractions) was prescribed to the 70-85% isodose. The response was evaluated with a CTscan performed 6-8 weeks after the last treatment and routinely thereafter. The median follow-up was 4 months (range: 2-11). No severe toxicity due to the marker placement was seen. Pneumothorax was not seen. The local control was 100%. Four tumors in four patients showed a complete response, 15 tumors in 14 patients a partial response, and three tumors in two patients with metastatic disease had stable disease. No severe toxicity of marker placement was seen due to the appropriate choice of one of the three methods. CyberKnife tumor tracking with markers is feasible and resulted in excellent tumor response. Longer follow-up is needed to validate the local control.

[Access to medical records: who asks and why?]. / Accès au dossier médical: caractéristiques et motifs des demandeurs.

OBJECTIVE: The aim of the survey was to study the characteristics of patients who (or whose families) request access to their medical records, their satisfaction with the handling of their requests, and the reasons for them. METHODS: This prospective study analyzed all the requests for access to medical records sent to two hospitals and collected data from the hospitals at that time (characteristics of the requester, patient and hospitalization) and from the requesters afterwards (opinion survey). RESULTS: The study reviewed 94 requests for medical records. Delays in providing the records exceeded the statutory periods. Most requests were intended to allow continuity of care, to provide information the patient did not receive during hospitalization, or because the patient needed to transmit it to a third party (new doctor, insurance, attorney, worker compensation). The hospitals mailed records to patients by regular mail in 90% of cases. One third of the patients were not satisfied by the handling of their request, complaining about the following difficulties: length of wait for records, complexity of the request procedure, its expense, absence of some documents, and difficulty in understanding the files without medical assistance. CONCLUSION: Improvements are needed, both to decrease the number of requests and to improve the requesters' satisfaction. Specific improvements are suggested.

[Contribution of day care general anaesthesia for dental care in children and handicapped patients]. / Apport de l'anesthésie générale ambulatoire pour les soins buccodentaires des enfants et des patients handicapés.

Dental surgeons, pediatrists and doctors daily note the precocity and the importance of caries in children. This evolution makes essential the general anaesthesia in paediatric dentistry among the therapeutic arsenal of pedodontists. Fortunately, with the greatest knowledge of the child physiology, the better control of the anaesthetic operative protocols, general anaesthesia is very efficient. Furthermore, the development of the day care treatment now allows the access of these treatments to an increasingly large public. For pedodontists and anaesthetist, generals anaesthesia is essentially indicated for children with many decays, presenting behaviour disorders, a physical or cerebral handicap, a turmoil engraves general state. This operating mode aims to restore: This particular aspect of the dental practice remains still too little developed and cannot answer the demands. The necessity made it a rule to set up a theoretical and practical training. This specialized dentistry waits for recognition on behalf of supervisory organisms and a similar message spread by all nursing persons.

[Care of handicapped children under general anesthesia in relation to different clinical parameters. Preliminary notes]. / Prise en charge des enfants handicapés sous anesthésie générale. Lien avec différents paramètres cliniques. Notes préliminaires.

Losses of teeth are significant and frequent among handicapped patients. For this study a sample of 58 children handicapped out of the 412 children dealt with for preserving dental care under general anaesthesia, was analyzed. If at equal age these children present a CAD on permanent teeth more significant, their undertake, the procedure of general anaesthesia and the preserving treatments under general anaesthesia do not present more difficulties than the child is handicapped or not. The factor determining in the effectiveness and the speed of the exempted acts seems to be the training of the dental care team.

[Care of handicapped children under general anaesthesia. Relationships with various clinical parameters. Preliminary notes]. / Undertake handicapped children under general anaesthesia. Link with various clinical parameters. Preliminary notes.

Losses of teeth are significant and frequent among handicapped patients. For this study a sample of 58 children handicapped out of the 412 children dealt with for preserving dental care under general anaesthesia, was analyzed. If at equal age these children present a CAD on permanent teeth more significant, their undertake, the procedure of general anaesthesia and the preserving treatments under general anaesthesia do not present more difficulties than the child is handicapped or not. The factor determining in the effectiveness and the speed of the exempted acts seems to be the training of the dental care team.

Study of the drug-drug interaction between simvastatin and cisapride in man.

OBJECTIVE: The objective of our study was to evaluate in humans the drug-drug interaction occurring during the concomitant administration of cisapride and simvastatin, two well-known substrates of CYP3A4. METHODS: Eleven healthy men aged between 20 years and 35 years gave their written informed consent to participate in the study. Each participant received repeated doses of cisapride and/or simvastatin. At first, subjects received cisapride alone, 10 mg every 8 h, for 3 days. Then, the drug was given at the same regimen during concomitant administration of simvastatin, 20 mg every 12 h for 4 days, starting on the night of day 3. Finally, cisapride was stopped and subjects received simvastatin (20 mg every 12 h) for four additional days. RESULTS: Simvastatin administration caused a 14 +/- 20% increase in the AUC0-8 of cisapride. In contrast, plasma concentrations of simvastatin were unaltered by the coadministration of cisapride, whereas plasma concentrations of simvastatin acid, its active metabolite, were decreased by 33 +/- 24%. CONCLUSION: The concomitant administration of the prokinetic agent cisapride and the 3-hydroxy-3-methylgluaryl CoA reductase inhibitor simvastatin resulted in altered pharmacokinetics of both drugs. Increased plasma concentrations of cisapride suggest that some patients may be at risk of toxicity while receiving both drugs, whereas the decrease in simvastatin acid plasma concentrations suggests that cholesterol lowering effects of simvastatin treatment may be blunted.

Determinants of the functional interaction between the soluble GM-CSF receptor and the GM-CSF receptor beta-subunit.

The GM-CSF receptor consists of a GM-CSF specific low affinity alpha-subunit (GMRalpha) and a beta-subunit (betac) that associates with GMRalpha in the presence of GM-CSF to form a high-affinity complex. A splice variant soluble isoform of GMRalpha (solalpha) consists of the extracellular domain of GMRalpha and a unique 16-amino acid C-terminal domain. Exogenously administered solalpha is unable to associate with betac on the cell surface either in the presence or absence of GM-CSF. However, paradoxically, co-expression of solalpha with betac results in the ligand-independent association of solalpha with betac on the cell surface via the C-terminal domain of solalpha. To study the interaction and functional characteristics of the solalpha-betac complex we engineered a soluble betac-subunit (ECDbeta) and expressed it alone and with solalpha. Co-expressed but not independent sources of solalpha and ECDbeta could be co-precipitated in the absence of ligand demonstrating the extracellular domain of betac was sufficient for association with solalpha upon co-expression. However, independent sources of solalpha could associate with ECDbeta in the presence of GM-CSF as could a C-terminal deficient solalpha mutant (ECDalpha) and the addition of ECDbeta to ECDalpha and GM-CSF was associated with a conversion from a low- to high-affinity ligand-receptor complex.

Identification of the soluble granulocyte-macrophage colony stimulating factor receptor protein in vivo.

On the basis of the finding of alternatively spliced mRNAs, the alpha-subunit of the receptor for GM-CSF is thought to exist in both a membrane spanning (tmGMRalpha) and a soluble form (solGMRalpha). However, only limited data has been available to support that the solGMRalpha protein product exists in vivo. We hypothesized that hematopoietic cells bearing tmGMRalpha would have the potential to also produce solGMRalpha. To test this hypothesis we examined media conditioned by candidate cells using functional, biochemical, and immunologic means. Three human leukemic cell lines that express tmGMRalpha (HL60, U937, THP1) were shown to secrete GM-CSF binding activity and a solGMRalpha-specific band by Western blot, whereas a tmGMRalpha-negative cell line (K562) did not. By the same analyses, leukapheresis products collected for autologous and allogeneic stem cell transplants and media conditioned by freshly isolated human neutrophils also contained solGMRalpha. The solGMRalpha protein in vivo displayed the same dissociation constant (Kd = 2-5 nmol) as that of recombinant solGMRalpha. A human solGMRalpha ELISA was developed that confirmed the presence of solGMRalpha in supernatant conditioned by the tmGMRalpha-positive leukemic cell lines, hematopoietic progenitor cells, and neutrophils. Furthermore, the ELISA demonstrated a steady state level of solGMRalpha in normal human plasma (36 +/- 17 pmol) and provided data suggesting that plasma solGMRalpha levels can be elevated in acute myeloid leukemias. (Blood. 2000;95:461-469)

Critical care nurses' perceptions of DNR status.

PURPOSE: To describe the perceptions of nurses regarding do-not-resuscitate (DNR) decisions in critical care settings. DESIGN: A survey assessing knowledge, attitudes, and practices concerning DNR status was distributed to all critical care nurses who were registered with the provincial licensing body in Alberta, Canada, and held positions of staff nurse, educator, or manager. METHODS: Four hundred and five surveys were completed and returned. Descriptive analyses were conducted. FINDINGS: The term "DNR" was found to be ambiguous. The rationale for DNR orders were also not well articulated in practice. Although nurses believed that patients, families, and nurses should participate in DNR decisions, physicians were most often cited as being responsible for the decision. CONCLUSIONS: Documentation of a comprehensive patient treatment plan and awareness of the rationale for DNR designation are strategies suggested to help achieve desire patient care goals in critical care settings.

Importance of experience for older home care workers in facing up to the constraints of work.

Home care workers (HCWs) are at risk from injury. A case study was undertaken in a local community health center in order (1) to identify the constraints that introduce risk into the work of HCWs, and (2) to study the strategies they apply, depending on their age, to reduce the effects of those constraints. Observation and semistructured interviews were the main sources of data. Analysis shows that HCWs aged 45 or over sometimes adopt different postures from those used by their younger colleagues. During physical care, the HCWs also carry out screening and social support tasks that are not recognized in the organization of their work. Older workers develop strategies that help them save time, refine their screening and support methods, protect themselves against accidents, and react properly in emergencies or dangerous situations. Because the changes that can be made in patients' homes are limited, the expertise of experienced HCWs is essential. The organization of work must maintain a certain flexibility to allow the workers to use their strategies.

[Improvement of prescriptions for serum tumor markers in a general hospital]. / Amélioration de la prescription de marqueurs tumoraux sériques dans un hôpital général.

OBJECTIVES: Using a standardized prescription sheet we attempted to improve requests for serum tumor markers in a general hospital. METHODS: Over two 35-day periods before and one year after defining a local prescription consensus and introducing a new prescription sheet, we counted the number of orders for five tumor markers (CEA, CA 19-9, CA 15-3, CA 125, alpha FP) and determined their compliance to the defined prescription protocol. RESULTS: Between the two study periods, the number of prescriptions for the designated tumor markers fell by 24%, from 153 requests in 94 patients to 123 requests in 99 patients, despite a 6% increase in the number of admissions. There was a significant reduction in the number of serum markers orders per prescription (from 1.6 to 1.2) although the distribution by tumor marker remained unchanged. Compliance to the prescription protocol improved, rising from 65 to 87% in units where the pre-protocol compliance rate was below 80%. The rate of compliance was not correlated with correct completion of the new prescription sheet (91% vs 86% respectively). The 6-month cost-savings was estimated at 31,104 FF using the general French nomenclature for laboratory tests. Direct cost reduction was estimated at 5,688 FF. CONCLUSION: Long-lasting improvement of serum tumor marker prescriptions can be achieved in a general hospital. Obtaining a local consensus implicating all prescribing units seems more important than a change in the presentation of the prescription sheet.

The soluble granulocyte-macrophage colony-stimulating factor receptor's carboxyl-terminal domain mediates retention of the soluble receptor on the cell surface through interaction with the granulocyte-macrophage colony-stimulating factor receptor beta-subunit.

The hematopoietic cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF) mediates its activity through binding to cell-surface receptors. The high-affinity GM-CSF receptor (GMR) consists of two transmembrane-anchored subunits: a ligand-specific, low-affinity subunit (GMRalpha); and a signal-transducing beta-subunit (GMRbeta). The human GMRalpha subunit also exists in a soluble isoform (SOLalpha) which antagonizes GM-CSF activity in vitro. Previous studies by us have shown that coexpression of SOLalpha and a mutated GMRbeta in BHK cells results in retention of SOLalpha on the cell surface and the formation of an intermediate affinity binding complex (Kd approximately 300 pM). This paper investigates the mechanism of the retention of SOLalpha on the cell surface. The data demonstrate that SOLalpha is anchored by a direct, ligand-independent interaction with GMRbeta which also occurs when SOLalpha is coexpressed with wild-type GMRbeta. However, SOLalpha and wild-type GMRbeta form a complex which binds GM-CSF with high affinity (Kd = 39 pM), indistinguishable from the binding characteristics of the TMalpha/GMRbeta complex. The experiments further reveal that the interaction between SOLalpha and GMRbeta is abrogated by removal of the unique 16 amino acid carboxyl-terminal domain of SOLalpha. Specific mutation of cysteine 323 in this carboxyl-domain to alanine also eliminates the cell-surface retention of SOLalpha identifying this residue as being necessary for the formation of the SOLalpha/GMRbeta complex.