Azetidine-2-Carboxylic Acid-Induced Oligodendrogliopathy: Relevance to the Pathogenesis of Multiple Sclerosis.

The naturally occurring imino acid azetidine-2-carboxylic acid (Aze) is consumed by humans and can be misincorporated in place of proline in myelin basic protein (MBP) in vitro. To determine Aze effects on the mammalian CNS in vivo, adult CD1 mice were given Aze orally or intraperitoneally. Clinical signs reminiscent of MBP-mutant mice occurred with 600 mg/kg Aze exposure. Aze induced oligodendrocyte (OL) nucleomegaly and nucleoplasm clearing, dilated endoplasmic reticulum, cytoplasmic vacuolation, abnormal mitochondria, and Aze dose-dependent apoptosis. Immunohistochemistry demonstrated myelin blistering and nuclear translocation of unfolded protein response (UPR)/proinflammatory molecules (ATF3, ATF4, ATF6, eIF2α, GADD153, NFκB, PERK, XBP1), MHC I expression, and MBP cytoplasmic aggregation in OL. There were scattered microglial nodules in CNS white matter (WM); other CNS cells appeared unaffected. Mice given Aze in utero and postnatally showed more marked effects than their dams. These OL, myelin, and microglial alterations are found in normal-appearing WM (NAWM) in multiple sclerosis (MS) patients. Thus, Aze induces a distinct oligodendrogliopathy in mice that recapitulates MS NAWM pathology without leukocyte infiltration. Because myelin proteins are relatively stable throughout life, we hypothesize that Aze misincorporation in myelin proteins during myelinogenesis in humans results in a progressive UPR that may be a primary process in MS pathogenesis.

Proline: the distribution, frequency, positioning, and common functional roles of proline and polyproline sequences in the human proteome.

Proline is an anomalous amino acid. Its nitrogen atom is covalently locked within a ring, thus it is the only proteinogenic amino acid with a constrained phi angle. Sequences of three consecutive prolines can fold into polyproline helices, structures that join alpha helices and beta pleats as architectural motifs in protein configuration. Triproline helices are participants in protein-protein signaling interactions. Longer spans of repeat prolines also occur, containing as many as 27 consecutive proline residues. Little is known about the frequency, positioning, and functional significance of these proline sequences. Therefore we have undertaken a systematic bioinformatics study of proline residues in proteins. We analyzed the distribution and frequency of 687,434 proline residues among 18,666 human proteins, identifying single residues, dimers, trimers, and longer repeats. Proline accounts for 6.3% of the 10,882,808 protein amino acids. Of all proline residues, 4.4% are in trimers or longer spans. We detected patterns that influence function based on proline location, spacing, and concentration. We propose a classification based on proline-rich, polyproline-rich, and proline-poor status. Whereas singlet proline residues are often found in proteins that display recurring architectural patterns, trimers or longer proline sequences tend be associated with the absence of repetitive structural motifs. Spans of 6 or more are associated with DNA/RNA processing, actin, and developmental processes. We also suggest a role for proline in Kruppel-type zinc finger protein control of DNA expression, and in the nucleation and translocation of actin by the formin complex.

Efficacy of oral palonosetron compared to intravenous palonosetron for the prevention of chemotherapy-induced nausea and vomiting associated with moderately emetogenic chemotherapy: a phase 3 trial.

BACKGROUND: Palonosetron (Aloxi(®), Onicit(®)) is a pharmacologically unique 5-HT3 receptor antagonist (RA) approved as a single IV injection for the prevention of nausea and vomiting induced by chemotherapy (CINV) of either moderate or highly emetogenic potential (MEC and HEC, respectively). An oral palonosetron formulation has been developed and compared to the IV formulation. METHODS: In this multinational, multicenter, double-blind, double-dummy, dose-ranging trial, 651 patients were randomly assigned to receive one of the following as a single dose prior to moderately emetogenic chemotherapy: oral palonosetron 0.25, 0.50, and 0.75 mg or IV palonosetron 0.25 mg. Patients were also randomized (1:1) to receive dexamethasone 8 mg IV or matched placebo on day 1. The primary endpoint was complete response (CR; no emesis, no rescue therapy) during the acute phase (0-24 h). RESULTS: Acute CR rates were 73.5, 76.3, 74.1, and 70.4 % for all patients receiving the palonosetron 0.25, 0.50, and 0.75 mg oral doses, and for IV palonosetron 0.25 mg, respectively; delayed CR (24-120 h) rates were 59.4, 62.5, 60.1, and 65.4 %, and overall CR (0-120 h) rates were 53.5, 58.8, 53.2, and 59.3 %, respectively. The addition of dexamethasone improved emetic control (acute CR rate) by at least 15 % for all groups except oral palonosetron 0.25 mg, where the acute CR improvement was approximately 7 %. Adverse events were similar in nature, incidence, and intensity for all oral and IV palonosetron groups, and were the expected adverse events for 5-HT3 RAs (primarily headache and constipation). CONCLUSION: Oral palonosetron has a similar efficacy and safety profile as IV palonosetron 0.25 mg and may be the preferred formulation in certain clinical situations. Among the tested oral treatments, a palonosetron 0.50-mg oral dose has been favored for the prevention of CINV in patients receiving moderately emetogenic chemotherapy due to a numerical gain in efficacy without a side effect disadvantage.

Palonosetron triggers 5-HT(3) receptor internalization and causes prolonged inhibition of receptor function.

Palonosetron is a 5-HT(3) receptor antagonist that has demonstrated superiority in preventing both acute and delayed emesis when compared to older first generation 5-HT(3) receptor antagonists. The objective of this work was to determine if palonosetron exhibits unique molecular interactions with the 5-HT(3) receptor that could provide a scientific rationale for observed clinical efficacy differences. Previously, we showed that palonosetron exhibits allosteric binding and positive cooperativity to the 5-HT(3) receptor in contrast to ondansetron and granisetron which exhibit simple bimolecular binding. The present work shows, through several independent experiments, that palonosetron uniquely triggers 5-HT(3) receptor internalization and induces prolonged inhibition of receptor function. After 24h incubation followed by dissociation conditions, [(3)H]palonosetron remained associated with whole cells but not to cell-free membranes (P<0.001). [(3)H]Palonosetron's binding to cells was resistant to both protease and acid treatments designed to denature cell surface proteins suggesting that the receptor complex was inside the cells rather than at the surface. Cells pretreated with unlabeled palonosetron subsequently exhibited reduced cell surface 5-HT(3) receptor binding. Palonosetron-triggered receptor internalization was visualized by confocal fluorescence microscopy using cells transfected with 5-HT(3) receptor fused to enhanced cyan fluorescent protein. In contrast, granisetron and ondansetron showed minimal to no effect on receptor internalization or prolonged inhibition of receptor function. These experiments may provide a pharmacological basis for differences noted in published clinical trials comparing palonosetron to other 5-HT(3) receptor antagonists.

Azetidine-2-carboxylic acid in the food chain.

Azetidine-2-carboxylic acid (Aze) 1 is a non-protein amino acid present in sugar beets and in table beets (Beta vulgaris). It is readily misincorporated into proteins in place of proline 2 in many species, including humans, and causes numerous toxic effects as well as congenital malformations. Its role in the pathogenesis of disease in humans has remained unexplored. Sugar beet agriculture, especially in the Northern Hemisphere, has become widespread during the past 150 years, and now accounts for nearly 30% of the world's supply of sucrose. Sugar beet byproducts are also used as a dietary supplement for livestock. Therefore, this study was undertaken as an initial survey to identify Aze-containing links in the food chain. Herein, we report the presence of Aze 1 in three sugar beet byproducts that are fed to farm animals: sugar beet molasses, shredded sugar beet pulp, and pelleted sugar beet pulp.

Misincorporation of the proline analog azetidine-2-carboxylic acid in the pathogenesis of multiple sclerosis: a hypothesis.

The misconstruction of proteins as a result of the displacement of one of more proline residues by their congener, azetidine-2-carboxylic acid (Aze), can result in various disorders. A number of lines of evidence suggest that multiple sclerosis may be among these. This concept adheres to the current view that multiple sclerosis lesions originate in the myelin sheath and that the underlying molecular abnormality involves the myelin basic protein. The Aze hypothesis posits that myelin basic protein and possibly other closely related molecules are misassembled in sites of lesion formation because of the substitution of Aze for one or more prolines within consensual epitopes. These include a highly conserved myelin basic protein hexapeptide sequence, PRTPPP, and an alpha helix bounded by prolyls. Recent studies have focused on the immunopathogenetic effects of posttranslational modification of this region. This hypothesis proposes that the domain is structurally, functionally, and antigenically altered by the intrusion of Aze in place of proline and that such misassembly may involve other proteins and adversely affect interactions with neighboring molecules. This report reviews evidence supporting the hypothesis that ingestion of Aze in the diet, in conjunction with genetic susceptibility, may predispose or contribute to the pathogenesis of multiple sclerosis.

Palonosetron exhibits unique molecular interactions with the 5-HT3 receptor.

BACKGROUND: Palonosetron is a 5-HT(3)-receptor antagonist (5-HT(3)-RA) that has been shown to be superior to other 5-HT(3)-RAs in phase III clinical trials for the prevention of acute, delayed, and overall chemotherapy-induced nausea and vomiting. The improved clinical efficacy of palonosetron may be due, in part, to its more potent binding and longer half-life. However, these attributes alone are not sufficient to explain the results with palonosetron. We sought to elucidate additional differences among 5-HT(3)-RAs that could help explain the observations in the clinic. METHODS: Receptor site saturation binding experiments were performed with [3H] palonosetron, [3H] granisetron, and [3H] ondansetron to obtain the corresponding Scatchard analyses and Hill coefficients. Diagnostic equilibrium binding experiments and kinetic dissociation experiments were conducted to examine competitive versus potential allosteric interactions between ondansetron, granisetron and palonosetron and the 5-HT(3) receptor. Finally, the long-term effect of the three antagonists on receptor function as measured by Ca2+ influx in HEK 293 cells expressing the 5-HT(3)-receptor was compared. RESULTS: Analyses of binding isotherms using both Scatchard and Hill plots suggested positive cooperativity for palonosetron and simple bimolecular binding for both granisetron and ondansetron. Equilibrium diagnostic tests discriminated differential effects of palonosetron on [3H] ligand binding indicating that palonosetron was an allosteric antagonist whereas granisetron and ondansetron were competitive antagonists. Using dissociation rate strategies, palonosetron was shown to be an allosteric modifier that accelerated the rate of dissociation from the receptor of both granisetron and ondansetron. Differences in the binding mode of palonosetron to the 5-HT(3) receptor were shown to have an impact on receptor function. In these experiments, cells were incubated with each antagonist, followed by infinite dilutions and dissociation for 2.5 h; cells previously incubated with either granisetron or ondansetron showed calcium-ion influx similar to control cells that had not been exposed to a 5-HT(3) receptor antagonist. In contrast, substantial inhibition of calcium-ion influx was observed in cells that had been incubated with palonosetron. CONCLUSIONS: Palonosetron exhibited allosteric binding and positive cooperativity when binding to the 5-HT(3) receptor. Palonosetron also triggered functional effects that persisted beyond its binding to the 5-HT(3) receptor at the cell surface. Differences in binding and effects on receptor function may be relevant to the unique beneficial actions of palonosetron. To our knowledge, this is the first report showing palonosetron's interaction with the 5-HT(3) receptor at the molecular level, clearly differentiating it from other 5-HT(3)-RAs.

New approaches to chemotherapy-induced nausea and vomiting: from neuropharmacology to clinical investigations.

Nausea and vomiting are considered to be among the most distressing consequences of cytotoxic chemotherapies. Currently, there are several novel 5-HT(3) receptor antagonists for the treatment of chemotherapy-induced nausea and vomiting (CINV), including ondansetron, granisetron, and dolasetron. These agents provide significant improvement in the management of acute emesis but are ineffective at preventing delayed emesis. In 2003, a new 5-HT(3) receptor antagonist, palonosetron HCL (Aloxi), was introduced to the U.S. market. Palonosetron was found to be effective in preventing delayed CINV. Indeed, palonosetron was the first and only 5-HT(3) receptor antagonist approved by the FDA for the prevention of both acute and delayed CINV. More recently, studies on the role of substance P in the emetic process led to the development of aprepitant (Emend) for the prevention of delayed emesis in combination with 5-HT(3) receptor antagonists. Despite these major advances, CINV remains uncontrolled in some patients. Current efforts are focused on treating refractory emesis and include both the clinical evaluation of compounds marketed for other indications and the preclinical evaluation of novel molecules targeting other transmitters in the emetic pathway. Ongoing work in pharmacogenomics has postulated several candidate genes that could be involved in emetic sensitivity and responsiveness to antiemetic therapy. Investigations into the pharmacogenomics of CINV may someday be able to aid in the identification of high risk patients and patients unlikely to respond to conventional therapies.

Azetidine-2-carboxylic acid in garden beets (Beta vulgaris).

Azetidine-2-carboxylic acid (L-Aze) is a toxic and teratogenic non-protein amino acid. In many species, including man, L-Aze is misincorporated into protein in place of proline, altering collagen, keratin, hemoglobin, and protein folding. In animal models of teratogenesis, it causes a wide range of malformations. The role of L-Aze in human disease has been unexplored, probably because the compound has not been associated with foods consumed by humans. Herein we report the presence of L-Aze in the garden or table beet (Beta vulgaris).

Rankings and symptom assessments of side effects from chemotherapy: insights from experienced patients with ovarian cancer.

GOALS OF WORK: Although many patients with ovarian cancer achieve favorable responses to primary chemotherapy, the majority of women will experience recurrence of their cancer. Selection of second- or third-line chemotherapy ultimately depends on patient preferences for different side effects. To better understand this process, we evaluated preferences and symptom distress in patients with ovarian cancer. PATIENTS AND METHODS: A total of 70 women with ovarian cancer who had previously received at least three cycles of platinum-based chemotherapy and currently undergoing chemotherapy for newly diagnosed or recurrent disease were interviewed in an outpatient chemotherapy clinic. The patients were asked to rank order 27 health states using a modified visual analog scale and to complete the Memorial Symptom Assessment Scale (MSAS). MAIN RESULTS: Most favorable health states included perfect health, clinical remission and complete control of chemotherapy-induced nausea and vomiting (CINV). Least favorable health states included more severe CINV health states and death. Patients on first-line chemotherapy had less symptom distress, and rated sexual dysfunction, fatigue and memory loss more favorably than patients on second- or third-line chemotherapy (P<0.05). Married patients generally had less symptom distress compared to patients who were not married, but married patients indicated more distress with sexual dysfunction (P=0.04). Married patients rated alopecia less favorably than unmarried patients (P=0.03), but married patients viewed certain CINV health states more favorably (P=0.02-0.04). CONCLUSIONS: CINV remains one of the most dreaded side effects of chemotherapy. Separate preference profiles exist for patients with newly diagnosed and recurrent disease, as well as for married versus unmarried patients. While MSAS scores and VAS rankings showed consistency across some health states, this was not true for CINV, suggesting that current symptom status may only influence patient preferences for selected side effects.

Incidence of chemotherapy-induced nausea and emesis after modern antiemetics.

BACKGROUND: The authors determined the incidence of acute and delayed chemotherapy-induced nausea and emesis (vomiting) (CINV) among patients receiving highly (HEC) or moderately (MEC) emetogenic chemotherapy. They also assessed whether physicians and nurses accurately recognized the incidence of acute and delayed CINV in their own practices. METHODS: A prospective, observational study of adult patients receiving HEC or MEC for the first time was performed. Before patient enrollment, medical oncologists and oncology nurses estimated the incidence of acute (Day 1) and delayed (Days 2-5) CINV after first administration of HEC and MEC in their own practices. Eligible patients from their practices then completed a 6-day diary including emetic episodes, nausea assessment, and antiemetic medication use. Observed incidence rates of acute and delayed CINV were compared with physician/nurse predictions. RESULTS: Twenty-four physicians and nurses and 298 eligible patients (67 receiving HEC and 231 receiving MEC) were recruited from 14 oncology practices in 6 countries. Greater than 35% of patients overall experienced acute nausea, whereas 13% experienced acute emesis. Delayed nausea and emesis were observed in 60% and 50% of HEC patients, respectively, and in 52% and 28% of MEC patients, respectively. Delayed symptoms appeared without acute symptoms after HEC (emesis, 38%; nausea, 33%) and MEC (emesis, 19%; nausea, 21%). Physicians and nurses accurately predicted the incidence of acute CINV but underestimated the incidence of delayed nausea and emesis after HEC by 21 and 28 percentage points, respectively, and delayed nausea after MEC by 28 percentage points. Greater than 75% of physicians and nurses underestimated the incidence of delayed CINV after both HEC and MEC. CONCLUSIONS: Physicians and nurses markedly underestimated the incidence of delayed nausea and emesis after both HEC and MEC. Delayed nausea and emesis, which may appear even in the absence of acute nausea and emesis, remain important targets for improved therapeutic intervention.

Perspectives on cancer therapy-induced mucosal injury: pathogenesis, measurement, epidemiology, and consequences for patients.

BACKGROUND: A frequent complication of anticancer treatment, oral and gastrointestinal (GI) mucositis, threatens the effectiveness of therapy because it leads to dose reductions, increases healthcare costs, and impairs patients' quality of life. The Multinational Association of Supportive Care in Cancer and the International Society for Oral Oncology assembled an international multidisciplinary panel of experts to create clinical practice guidelines for the prevention, evaluation, and treatment of mucositis. METHODS: The panelists examined medical literature published from January 1966 through May 2002, presented their findings at two separate conferences, and then created a writing committee that produced two articles: the current study and another that codifies the clinical implications of the panel's findings in practice guidelines. RESULTS: New evidence supports the view that oral mucositis is a complex process involving all the tissues and cellular elements of the mucosa. Other findings suggest that some aspects of mucositis risk may be determined genetically. GI proapoptotic and antiapoptotic gene levels change along the GI tract, perhaps explaining differences in the frequency with which mucositis occurs at different sites. Studies of mucositis incidence in clinical trials by quality and using meta-analysis techniques produced estimates of incidence that are presented herein for what to our knowledge may be a broader range of cancers than ever presented before. CONCLUSIONS: Understanding the pathobiology of mucositis, its incidence, and scoring are essential for progress in research and care directed at this common side-effect of anticancer therapies.

Clinical practice guidelines for the prevention and treatment of cancer therapy-induced oral and gastrointestinal mucositis.

BACKGROUND: Oral and gastrointestinal (GI) mucositis can affect up to 100% of patients undergoing high-dose chemotherapy and hematopoietic stem cell transplantation, 80% of patients with malignancies of the head and neck receiving radiotherapy, and a wide range of patients receiving chemotherapy. Alimentary track mucositis increases mortality and morbidity and contributes to rising health care costs. Consequently, the Multinational Association of Supportive Care in Cancer and the International Society for Oral Oncology assembled an expert panel to evaluate the literature and to create evidence-based guidelines for preventing, evaluating, and treating mucositis. METHODS: Thirty-six panelists reviewed literature published between January 1966 and May 2002. An initial meeting in January 2002 produced a preliminary draft of guidelines that was reviewed at a second meeting the same year. Thereafter, a writing committee produced a report on mucositis pathogenesis, epidemiology, and scoring (also included in this issue), as well as clinical practice guidelines. RESULTS: Panelists created recommendations from higher levels of evidence and suggestions when evidence was of a lower level and there was a consensus regarding the interpretation of the evidence by the panel. Panelists identified gaps in evidence that made it impossible to recommend or not recommend use of specific agents. CONCLUSIONS: Oral/GI mucositis is a common side effect of many anticancer therapies. Evidence-based clinical practice guidelines are presented as a benchmark for clinicians to use for routine care of appropriate patients and as a springboard to challenge clinical investigators to conduct high-quality trials geared toward areas in which data are either lacking or conflicting.

Evidence-based guidelines for managing mucositis.

OBJECTIVES: To discuss implementation of evidence-based clinical practice guidelines for mucositis. DATA SOURCE: Published articles, book chapters, web sources, clinical experience, unpublished manuscripts. CONCLUSION: Nurses can implement evidence-based guidelines but must include an evaluation component to determine effect on clinical outcomes. IMPLICATIONS FOR NURSING PRACTICE: Nurses have an integral role implementing and evaluating evidence-based practice guidelines for managing mucositis. When evidence is lacking and guidelines have gaps, nurses can play important roles in research to overcome these gaps.

Palonosetron: a unique 5-HT3 receptor antagonist indicated for the prevention of acute and delayed chemotherapy-induced nausea and vomiting.

Despite the advance in supportive care that occurred with the introduction of selective serotonin subtype 3 (5-HT3) receptor antagonists, control of chemotherapy-induced nausea and vomiting (CINV) with first-generation agents (ondansetron, dolasetron, and granisetron) is less than ideal. Palonosetron is a unique 5-HT3 receptor antagonist whose distinctive pharmacologic characteristics (ie, high 5-HT3 receptor binding affinity, prolonged half-life) result in superior clinical benefit. Superiority of palonosetron over ondansetron and dolasetron in the prevention of both acute and delayed CINV has been observed in each phase III trial conducted. Of note, such evidence of superiority has never been seen in US Food and Drug Administration (FDA) registration trials of other approved agents in this class. Recently approved by the FDA, palonosetron 0.25 mg intravenously is indicated for the prevention of acute nausea and vomiting associated with initial and repeat courses of moderately and highly emetogenic cancer chemotherapy. Unlike other 5-HT3 receptor antagonists, palonosetron is also indicated for prevention of delayed nausea and vomiting associated with initial and repeat courses of moderately emetogenic cancer chemotherapy. Palonosetron exhibits an excellent tolerability profile, with frequency, severity, and duration of adverse reactions similar to that of comparator agents. Unlike older agents that are considered therapeutically interchangeable at equipotent doses, palonosetron should be considered a clinically distinct and superior treatment for the prevention of CINV.

The burdens of cancer therapy. Clinical and economic outcomes of chemotherapy-induced mucositis.

BACKGROUND: Mucositis is a common but poorly studied problem among patients with solid tumors. The authors examined the clinical and economic outcomes of oral and gastrointestinal (GI) mucositis among patients receiving myelosuppressive chemotherapy. METHODS: A retrospective, random sample of 599 patients who developed chemotherapy-induced myelosuppression was followed for development of oral or GI mucositis and for development of subsequent episodes of bleeding or infection. Multilevel regression models of the risk of bleeding and infection were fit with chemotherapy cycles nested within patients. RESULTS: Mucositis developed during 37% of 1236 cycles of chemotherapy. Episodes of bleeding were significantly more common during cycles with GI mucositis than during cycles without GI mucositis (13% vs. 8%; P = 0.04). Episodes of infection were significantly more common during cycles with mucositis (especially GI mucositis) than during cycles without mucositis (73% vs. 36%; P < 0.0001). The mean durations of hospitalization were 4 days, 6 days, and 12 days during cycles with no mucositis, oral mucositis, and GI mucositis, respectively. After accounting for the depth and duration of myelosuppression and for other predictive factors, GI mucositis was associated with both bleeding (odds ratio [OR], 2.0; P = 0.01) and infection (OR, 2.24; P < 0.0001), whereas oral mucositis was associated with infection only (OR, 2.4; P < 0.0001). CONCLUSIONS: Mucositis was clinically and economically significant among patients with solid tumors who were receiving myelosuppressive chemotherapy. New preventive and therapeutic agents are needed.

Measuring chemotherapy-induced nausea and emesis.

BACKGROUND: Chemotherapy-induced nausea and emesis (CINE) is one of the most dreaded side effects of cancer therapy. To investigate the influence of these symptoms on a patient's quality of life (QOL), a validated tool measuring many domains is needed. METHODS: A QOL questionnaire consisting of scales from the European Organization for Research and Treatment of Cancer QLQ-C30, the Morrow Assessment of Nausea and Emesis, the Osoba Nausea and Emesis Module, and new items specific to nausea, emesis, and retching was constructed and administered daily for 7-9 days to outpatients receiving emetogenic chemotherapy. RESULTS: Test-retest and internal consistency reliabilities ranged from 0.44 to 0.84 and from 0.59 to 0.85, respectively. Item and scale correlations indicated good convergent and discriminant validity. Scales and items measuring similar factors (e.g., severity of emesis and severity of nausea) had strong correlations than did scales measuring dissimilar factors (e.g., cognitive functioning and physical functioning). The validity of known groups was demonstrated by significant differences (P < 0.01) in patients' QOL scores between days with no episodes of nausea, emesis, or retching, days with 1 or 2 episodes, and days with more than 3 episodes. Patients' QOL significantly decreased as the number of episodes per day increased (P < 0.001). CONCLUSIONS: A CINE QOL questionnaire that successfully measures the short-term impact of nausea, emesis, and retching on patients receiving emetogenic chemotherapy has been developed, largely as a battery of preexisting questionnaires. The psychometric properties of the new questionnaire show adequate reliability and validity to warrant its use in clinical trials and outcomes studies. CINE adversely affects many domains within a patient's QOL.

Alzheimer's disease, normal-pressure hydrocephalus, and senescent changes in CSF circulatory physiology: a hypothesis.

There is evidence that production and turnover of CSF help to clear toxic molecules such as amyloid-beta peptide (Abeta) from the interstitial-fluid space of the brain to the bloodstream. Two changes in CSF circulatory physiology have been noted as part of ageing: first, a trend towards lower CSF production, hence a decrease in CSF turnover; and second, greater resistance to CSF outflow. Our hypothesis is that, all else being equal, the initially dominant physiological change determines whether CSF circulatory failure manifests as Alzheimer's disease (AD) or as normal-pressure hydrocephalus (NPH). If CSF production failure predominates, AD develops. However, if resistance to CSF outflow predominates, NPH results. Once either disease process takes hold, the risk of the other disorder may rise. In AD, increased deposition of Abeta in the meninges leads to greater resistance to CSF outflow. In NPH, raised CSF pressure causes lower CSF production and less clearance of Abeta. The disorders may ultimately converge in vulnerable individuals, resulting in a hybrid as has been observed in several clinical series. We postulate a new nosological entity of CSF circulatory failure, with features of AD and NPH. NPH-AD may cover an important subset of patients who carry the diagnosis of either AD or NPH.

Pharmacoeconomic analysis of oprelvekin (recombinant human interleukin-11) for secondary prophylaxis of thrombocytopenia in solid tumor patients receiving chemotherapy.

BACKGROUND: Previous research has shown oprelvekin (recombinant human interleukin-11 [rhIL-11]) to be effective in reducing the requirements for platelet transfusions after myelosuppressive chemotherapy in patients who have previously experienced thrombocytopenia. The economic consequences of the routine use of this platelet growth factor and the usual standard of platelet transfusions for prophylaxis of severe chemotherapy-induced thrombocytopenia have not been compared. METHODS: The authors constructed a decision-analytic model to compare the alternatives of rhIL-11 versus usual care using probability, outcome, and cost data from previously published clinical trials and their own institutional sources. They incorporated the costs of platelet transfusions and adverse events from rhIL-11 into the analysis. Quality-of-life outcomes were not considered. The pharmacoeconomic analysis was based on the criterion of cost minimization from the payer's perspective. RESULTS: The expected cost of the usual care strategy for prophylaxis of severe thrombocytopenia (transfusion when platelets < 20000 microL(-1)) was US dollars 3495 for a 3-week cycle of chemotherapy. The prophylactic rhIL-11 strategy was more expensive, with an expected cost of US dollars 5328 over the same time period. Nonetheless, it was associated with fewer platelet transfusions, avoiding an average of 6.7 U compared with usual care. The savings from avoidance of platelet transfusion and adverse reactions to transfusion from the use of rhIL-11 were not offset by the substantial cost of the pharmaceutical. The greater expected costs from the rhIL-11 strategy were relatively insensitive to the unit price and efficacy of rhIL-11 and the costs of platelet transfusions and monitoring. CONCLUSIONS: From the payer's perspective, rhIL-11 cannot be considered a cost-saving clinical strategy compared with routine platelet transfusions for patients with severe chemotherapy-induced thrombocytopenia.