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Biomedical subjects

B G Arnason

Publications and source records attributed to B G Arnason.

At least 19 recordsLinked to original sources
PubMed2003

The use of mitoxantrone (Novantrone) for the treatment of multiple sclerosis [RETIRED]: report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology.

Mitoxantrone is the first drug approved for the treatment of secondary progressive multiple sclerosis (SPMS) in the United States. This assessment considers use of mitoxantrone in the treatment of MS. Mitoxantrone probably reduces the clinical attack rate and reduces attack-related MRI outcomes in patients with relapsing MS (Type B recommendation). Also, mitoxantrone may have a beneficial effect on disease progression in patients with MS whose clinical condition is worsening (Type B recommendation). The potential for serious toxicity of mitoxantrone, however, must be taken into account when considering this therapy in individual patients. Moreover, because the potential clinical benefits on disease progression appear to be only modest, the results of the single phase III trial should be replicated in another (and hopefully much larger) clinical study before this agent is widely recommended for the treatment of patients with MS.

Clinical Trials as Topic↗
PubMed2001

Etretinate augments interferon beta-1b effects on suppressor cells in multiple sclerosis.

BACKGROUND: Interferon beta treatment is only partially effective in multiple sclerosis (MS) suggesting a potential role for adjunctive therapies. Retinoids can augment the clinical efficacy of type 1 interferons in patients with cancer. We reasoned that the same might hold in MS. Interferon beta-1b added to peripheral blood mononuclear cells in vitro partially reverses the CD8 suppressor cell defect of patients with MS. All-trans retinoic acid added to peripheral blood mononuclear cells from untreated patients with MS or from controls potentiates this ability of interferon beta-1b to augment CD8 suppressor cell function in vitro. OBJECTIVE: To determine whether retinoid administration to patients with MS who are being treated with interferon beta-1b augments their CD8 suppressor cell function. SETTING: A university hospital MS clinic. PARTICIPANTS: Patients with MS who were being treated with interferon beta-1b, 14 patients with secondary progressive MS and 3 patients with relapsing remitting MS. RESULTS: Seventeen patients with MS received etretinate treatment for up to 6 months. Planned dosing was 10 mg 3 times daily for the first month, 25 mg twice daily for the second and third months, and 10 mg twice daily thereafter. The 25-mg twice daily dose was not well tolerated and of the 14 patients who remained in the phase 1 clinical trial through month 3 dose reduction to 10 mg thrice daily was required in 1 patient and to 10 mg twice daily in 4 patients. Eleven patients completed the trial. Etretinate treatment significantly augmented suppressor function over baseline values at 1, 3, and 6 months. No meaningful change was noted in disability or quality of life over the course of the phase 1 clinical trial. Neuropsychological testing of completers suggested improvement on selected aspects of verbal memory at 6 months compared with baseline values. CONCLUSIONS: Etretinate treatment at a dose of 10 mg twice or three times daily augments suppressor cell function in patients with MS receiving interferon beta-1b. Higher dose etretinate treatment (25 mg twice daily) is poorly tolerated by patients with MS. Even at 10 mg twice daily adverse experiences involving the mucous membranes and the skin become troublesome for some, but not all, patients. Whether pulse therapy or administration of retinoid restricted to the day of interferon beta dosing will also augment suppressor function, while being better tolerated, remains to be determined.

Adjuvants, Immunologic↗
PubMed2001

Design and expression of polymeric immunoglobulin fusion proteins: a strategy for targeting low-affinity Fcgamma receptors.

We have developed a family of cloning vectors that direct expression of fusion proteins that mimic aggregated immunoglobulin (IgG) (AIG) and immune complex function with respect to their interactions with FcgammaR and that allow for the inclusion and targeting of a second protein domain to cells expressing FcgammaR. This was accomplished by expressing multiple linear copies of the hinge and CH2 domains (HCH2) of human IgG(1) fused to the framework region of human IgG(1). Convenient restriction sites allow for the facile introduction of additional amino-terminal domains. The resulting molecule is tripartite. The carboxyl-IgG(1) framework domain provides stability and permits dimerization, and the intervening polymer provides increased effector function and targeting to FcgammaR while the amino-terminal domain can deliver an additional signal to cells expressing FcgammaR. To demonstrate the utility of the vectors, the extracellular domain of human CD8alpha was expressed as a HCH2 polymer fusion protein. The fusion proteins were secreted in useful amounts from polyclonal cell lines established in Sf9 cells following transfection and selection with G418. The biological activity of the recombinant CD8alpha-HCH2 polymers was determined and compared to those of AIG and an anti-CD16 monoclonal antibody using an in vitro assay. The activity of the fusion proteins positively correlates to the number of HCH2 units. The largest polymer tested was severalfold more potent than AIG at similar concentrations. The HCH2 polymers described here represent a new strategy in the design of recombinant proteins for the therapeutic targeting of FcgammaR in autoimmune disorders.

Animals↗
PubMed1999

Cytokine secretion by deltagamma and alphabeta T cells in monophasic experimental autoimmune encephalomyelitis.

Mononuclear cells were isolated from the central nervous system (CNS), lymph nodes (LN), spleen and blood, over the course of murine monophasic experimental autoimmune encephalomyelitis (EAE). Individual cytokine secreting T cells were enumerated. IL-2-secreting alphabeta T cells were numerous at all sites at disease onset. By disease peak their numbers had fallen profoundly; they remained low thereafter. IL-2 secreting gammadelta T cells were rare throughout. IFN-gamma-secreting cells were plentiful at all sites at disease onset. gammadelta T cells comprised 7% of total and 20% of IFN-gamma-secreting CNS-derived cells at disease onset; values at disease peak were 12 and 40% respectively. IL-4-secreting alphabeta T cells were rare in the CNS and LN throughout and did not increase in the spleen from baseline values. In contrast, splenic IL-4-secreting gammadelta T cells had increased to four-fold baseline values at disease onset and seven-fold at disease peak. Recovery from EAE is associated with a global inhibition of IL-2-secreting alphabeta T cells and to a lesser extent with IFN-gamma-secreting alphabeta and gammadelta T cells, whereas IL-4-secreting gammadelta T cells increase in the spleen as disease evolves.

Animals↗
PubMed1999

Treatment of multiple sclerosis with interferon beta.

Interferon beta is a cytokine that modulates immune responsiveness. Treatment with recombinant interferon b, either subcutaneously or intramuscularly, favorably affects the natural history of multiple sclerosis. Attack frequency and attack severity are both reduced and the progression of accumulating disability is slowed. Magnetic resonance image scanning of treated patients reveals a lessening of accumulating permanent disease burden and an up to 80% reduction in newly active lesions, the majority subclinical, within the white matter of the brain. Many newly active lesions resolve spontaneously. The drug is well tolerated and safe. Systemic flu-like symptoms, transient in nature, commonly follow drug injection when treatment begins, but these usually lessen in frequency and severity over the first few weeks on drug. Red skin reactions are usual at sites of subcutaneous injection. Interferon b treatment is only partially effective. There is an unmet need to do better in the therapy of multiple sclerosis.

Adjuvants, Immunologic↗
PubMed1999

Immunologic therapy of multiple sclerosis.

Three interferon beta preparations (Betaseron, Avonex, and Rebif) have shown efficacy in the treatment of relapsing-remitting multiple sclerosis (MS). Attack frequency is reduced by 30% and major attacks to an even greater extent. Accumulating disease burden as measured by annual T2-weighted magnetic resonance imaging is markedly lessened, and disease activity as measured by serial gadolinium-enhanced MRI scanning is reduced by over 80%. A fourth preparation, Copaxone, a basic copolymer of four amino acids, lessens MS attack frequency by 30% and also lessens disease activity as measured by gadolinium-enhanced MRI. Betaseron lessens accumulation of disability in MS patients with secondary progressive disease regardless of the severity of disability at the time treatment is commenced. MS is now a treatable disease.

Adjuvants, Immunologic↗
PubMed1998

All-trans retinoic acid potentiates the ability of interferon beta-1b to augment suppressor cell function in multiple sclerosis.

OBJECTIVE: To determine the effects of combination all-trans retinoic acid (RA) and interferon beta-1b therapy on immune system functions potentially relevant to multiple sclerosis (MS). DESIGN: Interferon gamma-secreting cells, T suppressor cell function, and lymphocyte proliferative responses were assayed using peripheral blood mononuclear cells from patients with MS and control subjects under control conditions and in the presence of interferon beta-1b, RA, and the 2 combined. SETTING: A university hospital MS clinic. PARTICIPANTS: Seventeen patients with secondarily progressive MS and 25 control subjects. RESULTS: Interferon beta-1b use increased interferon gamma-secreting cell counts, augmented T suppressor cell function, and inhibited T-cell proliferation. Therapy with RA decreased interferon gamma-secreting cell counts, had a minimal positive effect on T suppressor cell function, and had no effect on T-cell proliferation. When RA and interferon beta-1b were combined, the inhibitory effect of RA on interferon gamma-secreting cells predominated, T suppressor cell function increased synergistically over the increment observed with interferon beta-1b use alone, and the inhibitory effect of interferon beta-1b alone on T-cell proliferation remained unchanged. CONCLUSIONS: Treatment with interferon beta-1b partially restores defective T suppressor cell function in patients with MS. This potentially beneficial action is synergistically potentiated by RA. Interferon beta-1b increases the number of interferon gamma-secreting cells in the circulation when treatment is initiated. A similar increment in interferon gamma-secreting cells is observed when interferon beta-1b is added to cultural peripheral blood mononuclear cells in vitro. This potentially deleterious action of interferon beta-1b is reversed by RA. Interferon beta-1b inhibits lymphocyte proliferation modestly but reproducibly. This action of interferon beta-1b is unaltered by RA. These data provide a rationale for a trial of combination treatment with interferon beta-1b and RA in patients with MS.

Antineoplastic Agents↗
PubMed1998

Immunoaugmenting effect of FK 506 on experimental allergic encephalomyelitis in Lewis rats.

The effect of the immunosuppressive drug FK 506 on encephalomyelitis (EAE) in Lewis rats was studied. Treatment that began during EAE induction delayed EAE onset, but when the disease started it was chronic/progressive and of unusual severity and duration, leading to death in many animals. Treatment started after onset of EAE shortened the disease. Forty seven days after immunization, extensive demyelination and inflammation were observed in the spinal cords of rats treated with FK 506 from the day of EAE induction. Rats treated after EAE onset had only minimal pathological abnormalities.

Administration, Oral↗
PubMed1997

Beta-trace gene expression is regulated by a core promoter and a distal thyroid hormone response element.

We isolated and characterized the human beta-Trace protein (betaTP) gene promoter. betaTP, also known as prostaglandin D2 synthase, is a lipocalin secreted from the choroid plexus and meninges into cerebrospinal fluid. Basal transcription of the betaTP gene is directed from a core promoter found within the first 325 bases of the 5'-flanking sequence. The betaTP gene promoter is responsive to thyroid hormone (3,3',5-triiodothyronine, T3) and efficiently repressed by unliganded human thyroid hormone receptor beta (TRbeta). Functional analysis of the betaTP promoter in TE671 cells revealed that responsiveness to T3 occurs in sequences 2.5 kilobase pairs 5' of the start site. Within the hormone-responsive region we identified a thyroid hormone response element (TRE) located from -2576 to -2562 base pairs relative to the transcription start site. The betaTP TRE is composed of two directly repeated consensus half-sites separated by a 3-base pair space (DR3). The betaTP TRE forms specific complexes with TRbeta. We have shown that a gene active in the choroid plexus and meninges is responsive to T3. T3 may play a role in the regulated transport of substances into the cerebrospinal fluid and ultimately the brain.

Base Sequence↗
PubMed1997

Role of interferons in demyelinating diseases.

IFN beta-1b reduces the frequency of major multiple sclerosis attacks by 50 percent. Serial MRI scanning over the course of the clinical trial that led to approval of the agent revealed a significant lessening both in disease activity and in accumulating burden of disease in IFN beta-1b-treated patients compared to placebo-treated controls. The mechanism by which IFN beta-1b exerts its beneficial effect in multiple sclerosis is unknown. T suppressor cell function fails during MS attacks and is persistently subnormal in multiple sclerosis patients with progressive disease. IFN beta-1b partially restores suppressor function in multiple sclerosis patients. IFN beta-1b also inhibits release of lymphotoxin, tumor necrosis factor, and interferon gamma, at least in vitro. All three cytokines are toxic to oligodendrocytes. In contrast; production of transforming growth factor beta-1 (TGF beta 1) is increased by IFN beta-1b. TGF beta 1 is an immunosuppressive cytokine. All of the above listed actions of IFN beta-1b could contribute to its beneficial effect. Perhaps all do.

Demyelinating Diseases↗
PubMed1996

Interferon beta in multiple sclerosis.

Interferon beta 1B (IFNbeta1b) lessens multiple sclerosis (MS) attack frequency and accumulating disease burden as assessed by MRI. The agent is an immune system modulator. The immune response in MS is thought to involve a delayed-type hypersensitivity (DTH) response mediated by Th1 type T cells. IFNbeta1b lessens expression of MHC-class II proteins on blood monocytes but only after a delay. This action could impede antigen presentation. Expression of the B7-1 costimulatory molecule on B cells is also reduced in MS patients receiving IFNbeta1b. Downregulation of B7-1 expression could inhibit Th1 cell activation. IFNbeta1b exerts an antiproliferative effect on T cells, an action which could lessen the magnitude of Th1 cell responses. Several cytokines are secreted by Th1 cells or by the monocytes/macrophages that they activate. IL-2, IFNgamma, lymphotoxin, and tumor necrosis factor (TNF) are made by activated Th1 type T cells, IL-1, and TNF by activated macrophages. IFNbeta1b increases IL-2 production in vitro but decreases production of IFNgamma, LT, and TNF. If these same effects occur in vivo, a substantial attenuation of the effector arm of DTH response would be anticipated. IFNbeta1b has no known effect on Th2 type T cells. It increases CD8 cell function including that of CD8 suppressor cells, the function of which is known to be deficient when MS is active. Production of the suppressive cytokines IL-10 and transforming growth factor beta-1 is increased in vitro by IFNbeta1b. Taken in sum, the immunomodulatory actions of IFNbeta1b acting in concert would be expected to attenuate DTH responses and exert a beneficial effect in MS, as is found.

Adjuvants, Immunologic↗
PubMed1996

Global inhibition of IL-2 and IFN-gamma secreting T cells precedes recovery from acute monophasic experimental autoimmune encephalomyelitis.

Actively induced experimental autoimmune encephalomyelitis (EAE) in the PL/J mouse is a monophasic disease. We isolated mononuclear cells (MNC) from the central nervous system (CNS), lymph node (LN), blood, and spleen over the course of EAE and counted the number of cells secreting IL-2, IFN-gamma or IL-4 in response to polyclonal stimulation. IL-2 secreting cells were present in the CNS at disease onset but absent at disease peak and at recovery. A profound transient drop in IL-2 secreting cells also occurred in LN, blood, and spleen at disease peak and during recovery. IFN-gamma secreting cell number decreased in all compartments as disease evolved. In contrast, IL-4 secreting cell number was greatest in the CNS at disease peak, i.e. IL-4 secreting cells rose as IL-2 and IFN-gamma secreting cells fell. IL-4 secreting cell number did not change appreciably in LN, blood, and splenic MNC as disease evolved. CNS MNC at disease peak failed to proliferate in response to anti-CD3 mAb but did so in response to IL-2. LN, blood and splenic MNC did proliferate in response to anti-CD3 mAb at disease peak and this proliferation was augmented by exogenous IL-2. After prolonged culture, proliferative response of CNS MNC to anti-CD3 mAb was restored. These results indicate that during monophasic EAE global suppression of naive T cell and Th1 T cell cytokine synthesis occurs but that T cell proliferative responsiveness is selectively inhibited in the CNS.

Acute Disease↗
PubMed1996

Management of patients receiving interferon beta-1b for multiple sclerosis: report of a consensus conference.

Results of a double-blind, placebo-controlled study in ambulatory patients with relapsing-remitting MS showed that interferon beta-1b reduced the rate of exacerbations by one-third compared with placebo and limited new disease activity in the brain as evidenced by MRI. Interferon beta-1b, administered subcutaneously at a dosage of 0.25 mg (8 million IU) every other day is indicated for the treatment of ambulatory patients with relapsing-remitting MS. Interferon beta-1b may help a wider range of patients, but it should be prescribed only for patients with a diagnosis of clinically definite or laboratory-supported definite MS. The decision to treat a patient with interferon beta-1b should be individualized; that is, based on each patient's clinical presentation and course of MS. The most common adverse effects include (1) injection-site reactions and (2) flu-like symptoms, which are generally manageable and usually abate after the first few months of treatment. Spasticity may increase. Patients with severe depression or suicidal ideation should be monitored carefully, and symptomatic treatment should be pursued. Interferon beta-1b is contraindicated in pregnant and nursing women. Interferon beta-1b is effective in reducing the progression of total disease burden as seen on MRI in patients with MS. Its use is relatively straightforward and generally does not require alteration in the symptomatic treatment of MS. Patient education and support remain the mainstays of maintaining compliance through the early phases of therapy.

Female↗
PubMed1996

Improved delayed visual reproduction test performance in multiple sclerosis patients receiving interferon beta-1b.

We assessed neuropsychological function longitudinally in 30 MS patients who participated in the pivotal trial of interferon beta-1b (IFN-beta-1b). Nine patients received high-dose IFN-beta-1b (8.0 million units), eight low-dose IFN-beta-1b (1.6 MIU), and 13 placebo. There was significant improvement in Wechsler Memory Scale Visual Reproduction-Delayed Recall scores between years 2 and 4 of the trial in MS subjects receiving high-dose IFN-beta-1b. Motoric performance, MRI lesion area, and depression rating scores did not correlate with this finding. Comparison of MRI at baseline and at years 2 and 4 revealed significant changes over time for the total cohort (p < 0.02). Mean lesion area in the high-dose group did not change over time, whereas the low-dose and placebo groups had increases in total lesion area of 28 and 36%, respectively, at year 4. Expanded disability status scale scores did not change significantly between years 2 and 4 of the trial, nor did they correlate with MRI lesion area at any assessment point. We conclude that high-dose IFN-beta-1b improves delayed visual reproduction test performance in MS patients, a finding unlikely to be explained by practice effects or brain lesion area.

Adult↗
PubMed1995

Beta-adrenergic agonists suppress chronic/relapsing experimental allergic encephalomyelitis (CREAE) in Lewis rats.

Chronic/relapsing experimental allergic encephalomyelitis (CREAE) serves as an animal model for relapsing/remitting multiple sclerosis. Treatment with the beta-adrenergic agonist isoproterenol or the beta 2-adrenergic agonist terbutaline significantly suppressed both the first acute attack and the number of relapses in CREAE Lewis rats. The number of relapses was decreased even when treatment with beta-adrenergic agonist was started after the onset of the first acute attack of CREAE. beta-adrenergic receptor number was increased significantly on splenocytes from CREAE rats as compared to healthy controls or CFA-injected rats. Terbutaline treatment of CREAE rats lowered the splenocyte receptor number to normal values.

Adrenergic beta-Agonists↗