Efficacy of minocycline in patients with amyotrophic lateral sclerosis: a phase III randomised trial.

BACKGROUND: Minocycline has anti-apoptotic and anti-inflammatory effects in vitro, and extends survival in mouse models of some neurological conditions. Several trials are planned or are in progress to assess whether minocycline slows human neurodegeneration. We aimed to test the efficacy of minocycline as a treatment for amyotrophic lateral sclerosis (ALS). METHODS: We did a multicentre, randomised placebo-controlled phase III trial. After a 4-month lead-in phase, 412 patients were randomly assigned to receive placebo or minocycline in escalating doses of up to 400 mg/day for 9 months. The primary outcome measure was the difference in rate of change in the revised ALS functional rating scale (ALSFRS-R). Secondary outcome measures were forced vital capacity (FVC), manual muscle testing (MMT), quality of life, survival, and safety. Analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00047723. FINDINGS: ALSFRS-R score deterioration was faster in the minocycline group than in the placebo group (-1.30 vs -1.04 units/month, 95% CI for difference -0.44 to -0.08; p=0.005). Patients on minocycline also had non-significant tendencies towards faster decline in FVC (-3.48 vs -3.01, -1.03 to 0.11; p=0.11) and MMT score (-0.30 vs -0.26, -0.08 to 0.01; p=0.11), and greater mortality during the 9-month treatment phase (hazard ratio=1.32, 95% CI 0.83 to 2.10; p=0.23) than did patients on placebo. Quality-of-life scores did not differ between the treatment groups. Non-serious gastrointestinal and neurological adverse events were more common in the minocycline group than in the placebo group, but these events were not significantly related to the decline in ALSFRS-R score. INTERPRETATION: Our finding that minocycline has a harmful effect on patients with ALS has implications for trials of minocycline in patients with other neurological disorders, and for how potential neuroprotective agents are screened for use in patients with ALS.

A transgenic mouse model for studying the clearance of blood-borne pathogens via human complement receptor 1 (CR1).

Complement receptor 1 (CR1) on the surface of human erythrocytes facilitates intravascular clearance of complement-opsonized pathogens. The need for complement activation can be circumvented by directly coupling the organism to CR1 using a bispecific monoclonal antibody heteropolymer (HP). Lack of a functional homologue to CR1 on mouse erythrocytes has made it difficult to study HP-dependent clearance of pathogens in small animals. We have developed a transgenic mouse that expresses human CR1 on erythrocytes. CR1 antigen is of appropriate size and in a clustered distribution as confirmed by immunoblotting and fluorescence microscopy, respectively. HP that immobilized bacteriophage PhiX174 prototype pathogen to erythrocyte CR1 of the transgenic mice increased the rate of clearance of the virus compared with HP that bound bacteriophage, but not CR1. This transgenic mouse model will allow evaluation of different HPs for their in vivo efficacy and potential as human therapeutics.

Obstructive lower urinary tract symptoms correlate with erectile dysfunction.

OBJECTIVES: To examine whether the severity of lower urinary tract symptoms (LUTS), when controlled for other factors, is related to erectile dysfunction (ED) in the male veteran population. Early evidence suggests that LUTS may be associated with ED in men. METHODS: A total of 181 male veterans were prospectively entered into the study. They completed the Sexual Health Inventory for Men (SHIM) and International Prostate Symptom Score (IPSS) questionnaires. Of the 181 men, 144 also underwent uroflowmetry, including determination of the postvoid residual urine volume. Demographic and medical history data were recorded. Pearson correlation coefficients and multiple linear regression analysis were used to examine the relationship between LUTS and ED, as well as the effects of age and comorbidities. RESULTS: The correlation coefficient (r) for the SHIM score with the total IPSS was -0.17 (P = 0.023); with the obstructive IPSS, it was -0.20 (P = 0.006); and with the irritative IPSS, -0.05 (P = 0.492). Age was the only other factor with a statistically significant correlation with the SHIM score (r = -0.23, P = 0.002). Multiple linear regression modeling showed obstructive IPSS (P = 0.001) and depression (P = 0.017) to be the only statistically significant predictors of the SHIM score. A consistent negative correlation was found between obstructive IPSS and the SHIM score across age groups, with the strongest effect for men aged 60 to 70 years (r = -0.412, P = 0.003). CONCLUSIONS: Obstructive LUTS correlated with, and were predictive of, ED, even after controlling for age and comorbidities. Although age correlated with ED, it did not add to the power of the multiple linear regression model composed of obstructive IPSS and depression.

Mental health in men treated for early stage prostate carcinoma: a posttreatment, longitudinal quality of life analysis from the Cancer of the Prostate Strategic Urologic Research Endeavor.

BACKGROUND: The current study was conducted to assess posttreatment changes in the mental components of health related quality of life in prostate carcinoma patients during the two years following diagnosis and management with radical prostatectomy, pelvic irradiation, or watchful waiting. METHODS: The authors studied the mental domains of general health related quality of life in 452 men recently diagnosed with early stage prostate carcinoma and treated with radical prostatectomy, pelvic radiation, or watchful waiting. Outcomes were assessed with the RAND 36-Item Health Survey, a validated health-related quality of life instrument that includes four mental domains. To minimize the influence of potentially confounding factors, the authors adjusted for age, comorbidity, prostate specific antigen (PSA) at diagnosis, and biopsy Gleason score. All subjects were drawn from CaPSURE, a national, longitudinal cohort. RESULTS: By 6-12 months after treatment, the active treatment groups began to show differences in mental health and vitality. By 15 months, surgery and radiation patients scored differently in all four mental domains. Over time, the gaps between mental domain scores grew wider among the treatment groups, with surgery patients performing the best, radiation patients performing the worst, and watchful waiting patients falling in between. CONCLUSIONS: The mental health profiles differ for patients undergoing surgery, radiation, or watchful waiting for early stage prostate carcinoma. Men with more serious disease, as evidenced by higher PSA levels or more aggressive histology, tended to worry more about it. Older men performed better, while sicker men performed worse, even though the older men tended to be sicker.

CD5-mediated specific delivery of DNA to T lymphocytes: compartmentalization augmented by adenovirus.

Specific DNA delivery has been achieved via interactions between an asialoorosomucoid-polylysine conjugate and the asialoglycoprotein receptor. We have now extended this technology to another cell type. In order to achieve DNA delivery uniquely to T cells, we have employed an antibody-polylysine conjugate which binds and is internalized via CD5. Binding analyses of the T101 monoclonal antibody to Jurkat cells and freshly isolated human peripheral T lymphocytes were performed and Scatchard plots revealed Kd values of 1.4 and 1.2 pM, respectively. To introduce DNA into the T cell, a complex of T101-polylysine and the luciferase plasmid was formed (T101-PL-DNA). 125I-labeled antibody alone or T101-PL-DNA complexes were both shown to internalize. Subcellular fractionation indicated that the complex remained in the endosomal compartment of the cell for up to 90 min. However, with the addition of adenovirus particles, there was a decrease of labeled complex in the endosomal fraction over time suggesting it was no longer 'tethered' to the endosome vesicle. In vitro transfections confirmed this result showing the addition of adenovirus particles during incubation resulted in increased expression of the luciferase protein. Without adenovirus, there was limited expression of the transduced gene. These data revealed that T101 can deliver DNA via an antibody-PL conjugate. The addition of adenovirus allowed the DNA to escape the endosome enabling expression of the reporter gene.

Fracture protection provided by long-term estrogen treatment.

The objective of the study was to determine the incidence rate of osteoporotic fractures among elderly women who had long-term postmenopausal estrogen replacement therapy (ERT) and to compare this with the incidence rate in women who had not used estrogen. In a previous retrospective cohort study based on medical record review in 1982, we showed that long-term ERT was associated with lower incidence of wrist and vertebral fractures. We have extended our follow-up of 490 women by adding a mean 8 years to the observation period, which more than triples the number of osteoporotic fractures. At the Kaiser Permanente Medical Center, San Francisco, a large health maintenance organization, a review of computer pharmacy records from 1968 through 1971 identified 245 postmenopausal women; all had begun estrogen within 3 years of menopause and had used estrogen for at least 5 years. From the same pharmacy records, 245 age-matched postmenopausal non-users were identified. Among estrogen users, mean length of use was 17.0 years, mean follow-up after treatment was 7.3 years and mean dose of conjugated oral estrogen was 0.9 mg daily. We found statistically significant reduction in the incidence of wrist and vertebral fractures in users compared with non-users. The age-adjusted incidence ratios (95% confidence intervals for wrist fractures were 0.55 (0.32-0.92) and for vertebral fractures were 0.57 (0.41-0.80). These results were not statistically significantly altered after adjustment for age of menopause, body mass index and smoking. It is concluded that long-term ERT confers statistically significant protection against wrist and vertebral fractures.

Targeted delivery of DNA using YEE(GalNAcAH)3, a synthetic glycopeptide ligand for the asialoglycoprotein receptor.

In vivo gene therapy shows promise as a treatment for both genetic and acquired disorders. The hepatic asialoglycoprotein receptor (ASGPr) binds asialoorosomucoid-polylysine-DNA (ASOR-PL-DNA) complexes and allows targeted delivery to hepatocytes. The tris(N-acetylgalactosamine aminohexyl glycoside) amide of tyrosyl(glutamyl) glutamate [YEE(GalNAcAH)3] has been previously reported to have subnanomolar affinity for the ASGPr. We have used an iodinated derivative of YEE(GalNAcAH)3 linked to polylysine and complexed to the luciferase gene (pCMV-Luc) in receptor-binding experiments to establish the feasibility of substituting ASOR with the synthetic glycopeptide for gene therapy. Scatchard analyses revealed similar Kd values for both ASOR and the glycopeptide. Binding and internalization of 125I-Suc-YEE(GalNAcAH)3 were competitively inhibited with either unlabeled ASOR or glycopeptide. The reverse was also true; 125I-ASOR binding was competed with unlabeled YEE(GalNAcAH)3 suggesting specific binding to the ASGPr by both compounds. Examination of in vivo delivery revealed that the 125I-labeled glycopeptide complex mimicked previous results observed with 125I-ASOR-PL-DNA. CPM in the liver accounted for 96% of the radioactivity recovered from the five major organs (liver, spleen, kidney, heart, and lungs). Cryoautoradiography displayed iodinated glycopeptide complex bound preferentially to hepatocytes rather than nonparenchymal cells. In vitro, as well as in vivo, transfections using the glycopeptide-polylysine-pCMV-luciferase gene complex (YG3-PL-Luc) resulted in expression of the gene product. These data demonstrate that the YEE(GalNAcAH)3 synthetic glycopeptide can be used as a ligand in targeted delivery of DNA to the liver-specific ASGPr.

Identification of functional domains in murine granulocyte-macrophage colony-stimulating factor using monoclonal antibodies to synthetic peptides.

Granulocyte-macrophage (GM)-CSF is an important hematopoietic cytokine that regulates proliferation and differentiation of macrophages, neutrophils, and eosinophils. In this study, we generated mAb to five synthetic peptides that correspond to regions along the murine GM-CSF molecule. The ability of anti-peptide mAb to bind to and inhibit biologic activity of murine (m) GM-CSF was determined. mAb with the highest neutralization titers were derived from mice immunized with peptide II, which correspond to amino acids 27 to 38 of mGM-CSF. Immunochemical studies showed that peptide II specifically blocked binding of anti-peptide II mAb to GM-CSF. mAb to two other peptides in the N-terminal half corresponding to residues 7 to 17 and 47 to 58, respectively, of mGM-CSF also inhibited GM-CSF-dependent proliferation and differentiation of murine bone marrow precursors for macrophages and granulocytes. Anti-peptide mAb also inhibited growth of a murine hematopoietic cell line FDCP1 and a murine T cell line HT-2, which was shown to be dependent on GM-CSF for growth in vitro. Biologic activity of both natural and recombinant mGM-CSF was neutralized by anti-peptide mAb. These findings indicate that epitopes in the N-terminal region of mGM-CSF are important for biologic activity, and the epitope defined by peptide II (residues 27 to 38) lies within a particularly important functional domain of the mGM-CSF molecule.

In vivo regulation of hemopoiesis by transforming growth factor beta 1: stimulation of GM-CSF- and M-CSF-dependent murine bone marrow precursors.

Injection of mice with either natural bovine bone-derived or human recombinant transforming growth factor beta 1 (TGF-beta 1) resulted in a significant increase of the macrophage and macrophage-granulocyte-forming capacity of their macrophage colony-stimulating factor (M-CSF)- and granulocyte-macrophage colony-stimulating factor (GM-CSF)-dependent bone marrow precursor cells. The increased potential for generating granulocytes and/or macrophages from bone marrow cells of mice injected with TGF-beta 1 was associated with an increase of the number of M-CSF- and GM-CSF-dependent bone marrow colony-forming units (CFU). The effect was selective, in that in vivo applied TGF-beta 1 did not affect interleukin 3 (IL-3)-dependent CFU. The data suggest that TGF-beta may be useful in recovery of bone marrow granulocyte- and macrophage-forming potentials following depletion caused by chemo- or radiotherapy.

Macrophage-derived factors increase low density lipoprotein uptake and receptor number in cultured human liver cells.

Recent evidence suggests the possibility that macrophages can influence lipoprotein metabolism. Therefore we investigated the ability of cultured macrophages to alter low density lipoprotein (LDL) uptake in a human liver cell line (HepG2). Conditioned media from phlogogenic-induced mouse peritoneal macrophages or from a human macrophage cell line stimulated with endotoxin increased HepG2 LDL uptake by as much as 60-70%. The increase was due, in part, to a significant macrophage-induced 40% increase in the number of LDL receptors per cell. Although macrophage conditioned media inhibited HepG2 cholesterol synthesis, the LDL receptor up-regulation did not appear to be due to the effects on cholesterol synthesis. The LDL receptor stimulatory activity was sensitive to proteolysis and heat. Its molecular mass was approximately 20 kDa based on gel filtration. Several macrophage secretory proteins were tested in HepG2 cultures for LDL uptake stimulation. Of these, oncostatin M (approximately 18 kDa by gel filtration) gave the strongest response. The rank order for LDL uptake stimulation was oncostatin M much greater than interleukin 6 = interleukin 1 = transforming growth factor-beta 1. A neutralizing antibody directed against oncostatin M inhibited the ability of conditioned media to up-regulate LDL receptors by 85%. Thus, our results indicate that macrophages can secrete several proteins that up-regulate LDL receptors in HepG2 cells and that most of the up-regulatory activity in macrophage conditioned media appears to be due to oncostatin M.

Inhibition of antibody response to Pseudomonas exotoxin and an immunotoxin containing Pseudomonas exotoxin by 15-deoxyspergualin in mice.

Immunotoxins are potent cell-killing agents that may be useful in the treatment of cancer. The early production of neutralizing antibodies to immunotoxins is one of the major limiting factors for their use in humans. 15-Deoxyspergualin (DSG), a derivative of spergualin, which is a metabolite of Bacillus laterosporus, has been found to have immunosuppressive activity in rodents, dogs, and primates. We examined the suppressive activity of DSG on the antibody response to Pseudomonas exotoxin in mice by enzyme-linked immunosorbent assay. Male BDF1 mice were immunized with a single dose of a nontoxic mutant of Pseudomonas exotoxin (40 micrograms) and then treated with i.p. injections of DSF at a dose of 10 mg/kg for 3 days. Although antibodies to Pseudomonas exotoxin were observed within 7 days in the control group, there was complete suppression of antibody production in the DSG-treated group. Immunosuppression has also been observed in animals immunized with multiple doses (10 mg x 7 d) of Pseudomonas exotoxin and treated with DSG at a dose of 5 mg/kg for 21 days. Similar immunosuppression was observed in mice given multiple doses of the immunotoxin, anti-Tac-LysPE40. We conclude that the immunosuppressive activity of DSG may be useful in increasing the duration of immunotoxin treatment.

Evaluation in vitro of adriamycin immunoconjugates synthesized using an acid-sensitive hydrazone linker.

A novel method for linking Adriamycin (ADM) to monoclonal antibodies is described in which the 13-keto position of the anthracycline is used as the attachment site to the linker arm. A new ADM acylhydrazone derivative, Adriamycin 13-[3-(2-pyridyldithio)propionyl]hydrazone hydrochloride, which contains a pyridyl-protected disulfide, was synthesized and used for conjugation to monoclonal antibodies (MAbs) that were thiolated with N-succinimidyl 3-(pyridyldithiol)propionate or 2-iminothiolane. This resulted in formation of a linker between MAb and drug that contained a disulfide bond. Conjugation conditions were optimized to yield conjugates with high ADM:MAb molar ratios. The final immunoconjugate yields were found to decrease as the ADM:MAb molar ratio of the conjugates increased. Stability studies indicated that ADM was released from the immunoconjugates at mildly acidic pHs ranging from 4.5-6.5. Treatment of immunoconjugates with mild reducing agent dithiothreitol resulted in release of an acylhydrazone derivative of ADM. Flow-cytometric studies showed that the binding activity of various MAbs following conjugation to ADM was preserved at ADM:MAb molar ratios up to 10. Antibody-directed cytotoxicity was demonstrated under several assay conditions using combinations of antigen-positive and antigen-negative cells and binding and nonbinding immunoconjugates. In several experiments, ADM immunoconjugates were more potent than equivalent amounts of unconjugated ADM.

T-cell receptor-CD4 physical association in a murine T-cell hybridoma: induction by antigen receptor ligation.

By employing flow cytometric analysis and fluorescence resonance energy transfer (FRET), we examined the physical relationship between the T-cell receptor-CD3 complex (Ti-CD3) and the CD4 molecule on helper T cells. Through the use of an L3T4-negative murine T-cell hybridoma infectant expressing the human CD4 gene and having antigen specificity for HLA-DR, we show that binding of the Ti-CD3 complex with an anti-CD3 monoclonal antibody induces its redistribution proximal to cell-surface CD4. FRET efficiency was 9.4% on cells labeled with rhodaminated anti-CD3 and fluoresceinated anti-CD4. FRET was found to be temperature dependent, since similarly treated cells held at 4 degrees C displayed a FRET efficiency of less than 1%. Energy transfer was evident within 3 min after warming cells to 37 degrees C. Energy transfer was not detected between Ti-CD3 and the abundantly expressed leukocyte common antigen (CD45). Of greater significance was our observation that hybridomas infected with a truncated CD4 gene lacking the cytoplasmic domain failed to transfer energy despite the fact that CD4 was expressed on the cell surface at levels equivalent to or greater than the wild type. These studies suggest that after crosslinking of the Ti-CD3 on CD4+ T cells, a physical association occurs between the antigen receptor complex and CD4 and that the association is dependent upon the presence of the cytoplasmic domain of CD4.

Immune responses associated with early survival after peroral infection with Toxoplasma gondii.

After peroral infection with cysts of Toxoplasma gondii, C57BL/6 mice died and A/J mice survived. To better understand the reasons for this difference in survival, host defenses during acute infection were studied: initial portal of entry of T. gondii contributed to susceptibility as more C57BL/6 mice survived after i.p. than peroral infection (p less than 0.001). Susceptible (C57BL/6) mice had more necrosis and inflammation in their brains, livers, and mesenteric lymph nodes than resistant (A/J) mice. Susceptible mice had less IgM antibody to T. gondii (p less than 0.0005) than resistant mice 7 days after infection, but amounts of IgG antibody to T. gondii were similar. Infection reduced percentages of spleen cells with the Lyt-2+ phenotype in susceptible (p less than 0.02) but not resistant mice; infection decreased percentages of spleen cells with the L3T4+ phenotype similarly in both strains of mice. Spleen cells from infected susceptible mice had greater depression in their blastogenic response to Con A (p less than 0.05) and produced significantly more IFN-gamma in culture with (p = 0.009) or without (p less than 0.05) Toxoplasma Ag than spleen cells from infected resistant mice. Infection increased serum levels of IFN-gamma substantially in susceptible but not resistant mice. Lymphocyte IL-2 production was similar in both groups of mice. Peritoneal macrophages from both strains of mice became activated to inhibit or kill T. gondii by 7 days after infection, but Kupffer cells became activated only in susceptible mice. These results indicate that increased resistance to peroral Toxoplasma infection is likely to be mediated by a number of immune responses acting together. They suggest that increased susceptibility may result from inadequately regulated inflammatory responses that increase tissue destruction.

Inhibition of macrophage-induced antigen-specific T-cell proliferation by interferon-gamma.

The effects of IFN-gamma on macrophage (M phi)-mediated antigen-specific T-cell proliferation was investigated. A well-defined assay system using purified resident populations of antigen-pulsed peritoneal M phi and immune T cells was used to measure M phi-induced antigen-specific T-cell proliferation. Antibody affinity purified or recombinant IFN-gamma inhibited M phi-induced T-cell proliferation when KLH-pulsed M phi from mice given IFN-gamma prior to KLH were cultured with KLH immune T cells from normal mice. Monoclonal rat anti-IFN-gamma antibody neutralized the inhibitory effect of IFN-gamma. This inhibition of T-cell proliferation occurred despite the fact that these M phi appeared to be activated by IFN-gamma treatment as measured by increased tumoricidal activity. The mechanism for the inhibition was unrelated to class II (Ia) expression, IL-1 secretion, and prostaglandin secretion. These results demonstrate the complex and sensitive role IFN-gamma has in regulating the immune response.

Influence of interferon gamma on B cell replication.

Semisolid agar culture techniques, recombinant murine gamma interferon, (Mu IFN gamma) and monoclonal anti-Mu IFN gamma antibodies were used to evaluate the role of interferon in mitogen-dependent B cell proliferation. Subtle, but significant, effects of interferon addition were noted when unseparated spleen cells were cultured. Depending on culture conditions, the cloning efficiency of the B cells was slightly increased by optimal concentrations of interferon. When the spleen cells were cultured over unstimulated peritoneal macrophages separated by an agar spacer, and especially when no other potentiators were added to the cultures, substantial enhancement of B cell proliferation routinely resulted. The mechanism of this effect was then investigated with macrophage depleted spleen cells as well as highly enriched, positively selected, B cell suspensions. Results of these experiments indicated that B cell replication can be modulated by direct interaction with interferon and again, the conditions of culture determined the magnitude and direction of the effect. Addition of anti-interferon antibodies, indomethacin, or interleukin 1 (IL-1) to the cultures did not influence the cloning efficiency of normal splenic B cells. Therefore, we found no evidence that endogenously produced interferon, prostaglandins, and IL-1 influence B cell colony formation. Since interferon stimulated macrophages dramatically improved B cell proliferation without direct cell contact, some other monokine may be involved. Therefore, gamma interferon can participate in humoral immune responses by influencing the expansion of activated B cells directly as well as indirectly via stimulation of macrophages.

A sensitive immunochemical assay for biologically active MuIFN-gamma.

An immunochemical assay for the detection of mouse gamma interferon (MuIFN-gamma) has been established. Using a purified monoclonal antibody (MAb) that neutralizes the antiviral activity of MuIFN-gamma, and a polyclonal antibody (PAb) prepared against affinity-purified MuIFN-gamma, we have developed a double-sandwich enzyme-linked immunosorbent assay (ELISA). The assay is specific for both natural and recombinant MuIFN-gamma and displays only background activity against MuIFN-alpha + beta, recombinant TNF (rTNF), human gamma interferon (HuIFN-gamma) and crude rat spleen cell supernatants. The assay is more sensitive and reproducible than the measurement of hydrogen peroxide (H2O2) release by macrophages, and is capable of detecting both crude and purified MuIFN-gamma down to 0.03 U/ml of antiviral activity, making this assay 10-100 times more sensitive than the conventional antiviral assay. The ELISA detects only biologically active MuIFN-gamma since treatment of the MuIFN-gamma at high temperature or low pH conditions resulted in abolishment of biological activity, as determined by inhibition of cytopathic effect, coincident with a dramatic decrease in ELISA titer.

Gamma interferon as a crucial host defense against Rickettsia conorii in vivo.

Gamma interferon (IFN-gamma) plays an important role as a host defense in rickettsial infection. Swiss Webster mice, which are resistant to Rickettsia conorii (Malish 7 strain) infection, were treated with a monoclonal antibody against mouse IFN-gamma. When the antibody-treated mice were inoculated with 12 50% tissue culture infective doses of R. conorii, the mortality was 47% and the morbidity was 100%. None of the control mice, which received the same dose of R. conorii, died or became ill. The enumeration of rickettsiae in organs by direct immunofluorescence in paraffin sections demonstrated higher quantities of rickettsiae in the spleen had liver of IFN-gamma-depleted mice as compared with those of the infected controls. The kinetic analysis of IFN-gamma levels in sera showed depletion in the treated mice. These results indicate that IFN-gamma plays an important role as a host defense in the early stage of rickettsial infection. Survival of some mice despite continued treatment with antibody to IFN-gamma suggests that other immune mechanisms may also be important.