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Biomedical subjects

B Diamond

Publications and source records attributed to B Diamond.

At least 91 records · Page 5Linked to original sources
PubMed1994

Pharmacokinetics of risperidone in chronic schizophrenic patients.

In a randomized, crossover study, 24 schizophrenic patients received a single 4-mg dose of risperidone in caplet or tablet form. Each of the two study periods lasted 5 days. Blood samples to determine (by radioimmunoassay) plasma levels of risperidone and its major metabolite, 9-hydroxy-risperidone (9-OH-risperidone), were obtained each day. The two formulations of risperidone were bioequivalent. Following are the mean pharmacokinetics of risperidone and risperidone + 9-OH-risperidone: area under the plasma concentration curve (AUC) from 0 to 96 hours; 278.0 and 716.9 ng.hr/mL; AUC from 0 to infinity, 291.9 and 762.4 ng.hr/mL; peak plasma concentration, 33.0 and 44.5 ng/mL; time to peak concentration, 1.39 and 1.78 hours; and elimination half-life, 14.93 and 23.04 hours. These results demonstrate that the active moiety (risperidone plus 9-OH-risperidone) has a half-life of 23 hours and reveal a pool of risperidone (terminal half-life, 14.9 hours) that may allow twice-daily or even once-daily dosing.

Adolescent↗
PubMed1993

Multiple encephalitogenic peptides of myelin basic protein in A.CA mice.

Experimental allergic encephalomyelitis (EAE) is an autoimmune disease of the central nervous system. It is mediated by T cells and is an animal model for the human disease multiple sclerosis. In most mouse strains that are susceptible to induction of EAE by myelin basic protein, a dominant peptide of myelin basic protein is recognized by encephalitogenic T cells. We report here the susceptibility of the A.CA strain (H-2f) to myelin basic protein induced EAE and that multiple peptides of myelin basic protein (1-11, 9-20, and 87-99) can induce disease in these mice. The finding that multiple epitopes of the same self-antigen can elicit EAE in an inbred strain of mouse raises the possibility of more heterogeneity in encephalitogenic peptides of the putative autoantigen in human disease than previous studies have suggested.

Amino Acid Sequence↗
PubMed1993

Mouse placental macrophages have a decreased ability to present antigen.

Large numbers of macrophages can be found in an animal's uteroplacental unit. This high concentration of macrophages suggests they must play an important role during placental development. To gain a better understanding of the functional capacity of placental macrophages, we have obtained a highly enriched placental macrophage culture and have derived several cell lines from this population. Both placental macrophages and cell lines show colony-stimulating factor 1-dependent growth, express Fc receptors, and can perform Fc-receptor-mediated phagocytosis. In addition, they express macrophage markers Mac-1, F4/80, and CD14. Although placental macrophages express major histocompatibility complex class II molecules constitutively, they display a decreased ability to present protein antigens to T cells. Since primary fetal liver macrophages of the same gestational stage also show a decreased ability to present antigens, this phenomenon may reflect a developmental stage of macrophages.

Animals↗
PubMed1993

Anti-DNA antibodies secreted by peripheral B cells of lupus patients have both normal and lupus-specific features.

Autoantibodies present in sera of patients with systemic lupus erythematosus (SLE) are found in low titer in sera of healthy individuals. Hence, it is possible that B cell populations in SLE patients and in normal individuals are homologous and in the absence of regulatory forces would secrete similar antibodies. We therefore studied antibody secretion of Epstein-Barr virus-transformed B cells of 20 SLE patients and 20 healthy subjects. Normal and lupus antibody repertoires did not differ significantly with respect to antigenic specificities, isotype, avidity, and titer. However, anti-DNA antibodies bearing the anti-DNA-associated idiotype 8.12 were found only in SLE. These findings suggest that the B cell repertoire of SLE and normal individuals is more similar than the serum antibody profile. However, part of the anti-DNA response in SLE probably reflects affinity (antigen driven) maturation as it differs in idiotype profile from anti-DNA response of normal individuals.

Antibodies, Antinuclear↗
PubMed1993

Cardiac alpha-myosin heavy chains differ in their induction of myocarditis. Identification of pathogenic epitopes.

BALB/c mice develop autoimmune myocarditis after immunization with mouse cardiac myosin, whereas C57B/6 mice do not. To define the immunogenicity and pathogenicity of cardiac myosin in BALB/c mice, we immunized mice with different forms of cardiac myosin. These studies demonstrate the discordance of immunogenicity and pathogenicity of myosin heavy chains. The cardiac alpha-myosin heavy chains of BALB/c and C57B/6 mice differ by two residues that are near the junction of the head and rod in the S2 fragment of myosin. Myosin preparations from both strains are immunogenic in susceptible BALB/c as well as in nonsusceptible C57B/6 mice; however, BALB/c myosin induces a greater incidence of disease. To further delineate epitopes of myosin heavy chain responsible for immunogenicity and disease, mice were immunized with fragments of genetically engineered rat alpha cardiac myosin. Epitopes in the region of difference between BALB/c and C57B/6 (residues 735-1032) induce disease in both susceptible and nonsusceptible mice. The data presented here demonstrate that pathogenic epitopes of both mouse and rat myosin residue in the polymorphic region of the S2 subunit. In addition, these studies suggest that polymorphisms in the autoantigen may be part of the genetic basis for autoimmune myocarditis.

Animals↗
PubMed1993

Characterization of two human anti-DNA antibodies bearing the pathogenic idiotype 8.12.

Antibodies against double stranded DNA (dsDNA) are characteristic of systemic lupus erythematosus (SLE) and have been implicated in disease pathogenesis. Up to one third of an SLE patient's anti-dsDNA antibodies can express the lambda L chain idiotype 8.12. Serum titers of this idiotype are elevated in 50% of SLE patients, and idiotypic antibodies are present in glomerular immune deposits associated with lupus nephritis. Two EBV transformed B cell lines, KS3 from a patient with SLE and SD6 from an individual without autoimmune disease, secrete 8.12+ IgG antibodies that bind dsDNA. The 8.12+ lambda L chains of these anti-DNA antibodies are encoded by members of the V lambda II gene family; the KS3 heavy chain is encoded by a VH4-DM1-DQ52-JH6b-C gamma 1 gene rearrangement and the SD6 heavy chain is encoded by a VH3-D21/9-JH6b-C gamma 1 rearrangement. Both of these monoclonal antibodies are somatically mutated: the KS3 antibody displays mutations in complementarity determining regions (CDRs) and the SD6 antibody in framework regions (FRs). The significance of these different patterns of mutation in two potentially pathogenic anti-DNA antibodies is discussed.

Amino Acid Sequence↗
PubMed1993

Cognitive and neurologic deficits in the MRL/lpr mouse: a clinicopathologic study.

OBJECTIVES: Determine if the MRL/lpr mouse develops neurological deficits and, if so, the pathologic basis for these deficits. Antiphospholipid antibodies (aPL) are associated with ischemic stroke, multiinfarct dementia, chorea, and cardiac valvular abnormalities. The MRL/lpr mouse develops high titer anticardioplin antibodies (aCL) suggesting that it may be used as a model for the neurological complications of aPL. METHODS: We undertook a prospective clinicopathologic study comparing the MRL/lpr mouse against its congenic strain, the MRL/+ mouse. We studied 15 MRL/pr and 15 MRL/lpr and 15 MRL/+ mice at 16 to 20 weeks and a group of 16 mice of each strain at 8 to 10 weeks. aCL and anti-DNA antibodies were measured by ELISA: Cognitive and neurological deficits were assessed by a water maze and a standardized rodent neurological examination. The brains and cardiac valves of the mice were then examined pathologically. RESULTS: The MRL/lpr mice had significantly elevated aCL at both ages. Cognitive and sensorimotor deficits were apparent at 16 weeks but no correlation could be found with aCL or anti-DNA titer. Even at 8 weeks the MRL/lpr mice performed poorer on the water maze when compared to their age matched congenic strain. No evidence of cerebral infarction was found but mononuclear infiltrates were found in the choroid plexus of all the MRL/lpr mice at both 10 and 20 weeks. No evidence of cardiac valve pathology was seen at 20 weeks. CONCLUSIONS: (1) The MRL/lpr mouse develops cognitive and neurologic deficits. The etiology of these deficits is not clear but may be related to early infiltration of the central nervous system with mononuclear cells. (2) Despite the elevated aCL, evidence of cerebral infarction or mitral valve abnormalities could not be found.

Animals↗
PubMed1992

The anti-DNA-associated idiotype 8.12 is encoded by the V lambda II gene family and maps to the vicinity of L chain CDR1.

The 8.12 idiotype is an anti-DNA-associated Id present on lambda L chains that are expressed at high titers in 50% of patients with systemic lupus erythematosus. Since this Id can be present on as much as a third of a patient's anti-DNA antibodies and is found in renal glomeruli, 8.12 is thought to be a marker for a subset of pathogenic anti-DNA auto-antibodies. A molecular analysis of the 8.12 positive antibodies was designed to explore the genetic basis of this Id. Monoclonal human B cell lines were generated by transformation with EBV and lambda L chain-secreting lines were analyzed for Id expression and V region gene usage. In this panel of Ig lambda cell lines, the 8.12 idiotype is encoded exclusively by members of the V lambda II gene family. The sequences of several 8.12+ and 8.12- V lambda II genes are reported here and are used to map the 8.12 Id to the vicinity of CDR1, as well as to further characterize the large and polymorphic V lambda II gene family.

Amino Acid Sequence↗
PubMed1992

Induction of tolerance to an IgG autoantibody.

Nonautoimmune mice transgenic for the heavy chain of an IgG2b anti-double-stranded-DNA antibody express the transgene in lymphoid organs and display partial allelic exclusion of this gamma 2b transgene. The spleens of these mice are characterized by marked B-cell depletion. Although there are B cells in these mice that express the transgene and recognize double-stranded DNA, they are anergic in vivo. Recovery from the state of anergy occurs in vitro after lipopolysaccharide stimulation. Thus this transgenic model demonstrates the induction of self tolerance to an IgG autoantibody.

Animals↗
PubMed1992

Lupus anti-DNA antibodies bearing the 8.12 idiotype appear to be somatically mutated.

Anti-DNA antibodies in systemic lupus erythematosus (SLE) sera were analyzed using an antiidiotype designated 8.12 which recognizes a determinant on lambda light chains highly expressed in SLE sera. Eight of ten normal individuals had peripheral blood lymphocytes which produced high-titered 8.12-positive antibodies, following transformation with Epstein Barr virus, implying that the 8.12-reactive sequence originates in the germline gene (GLG). Of 58 SLE sera, 32 contained elevated titers of 8.12-reactive antibodies. Twenty-three of these sera had 8.12-reactive anti-DNA antibodies, suggesting a strong correlation between 8.12 idiotype and DNA binding. Moreover, 20 of 26 8.12-reactive IgG antibodies and only 4 of 10 8.12-reactive IgM antibodies bound DNA (P less than 0.05). These observations strengthen our previous findings in myeloma sera that DNA binding is associated with IgG isotype in the 8.12 idiotype system and suggest that the acquisition of anti-DNA reactivity in antibodies bearing the GLG idiotype 8.12 is achieved by somatic mutation, a feature of an antigen-driven response.

Antibodies, Antinuclear↗
PubMed1992

Revisiting and revising suppressor T cells.

A great deal of experimental evidence supports the phenomenon of immunological suppression. The molecular mechanisms to explain the phenomenology have, however, remained controversial. In this review, the data are reinterpreted in light of the recent advances in the understanding of T-cell subsets, the cross-regulatory properties of lymphokines and the differential presentation capacities of different antigen-presenting cell types.

Animals↗
PubMed1992

Ventricle-to-brain ratio and symptoms at the onset of first-break schizophrenia.

Ventricle-to-brain ratio (VBR) was measured from the computed tomographic (CT) scans of 33 very recent-onset psychotic patients. Illness severity and positive and negative symptoms were also assessed in 21 of these patients with schizophreniform disorder. Forty-five neurology patients served as controls. Analyses revealed no significant differences between the VBR of the psychotic group as a whole, the schizophreniform subgroup, the affective psychotic subgroup, and the controls. Control subjects with a neurological diagnosis of vertigo or syncope had significantly higher VBR than the remainder of the control group and the psychotic group. When the psychotic group was compared to the control group minus those controls with syncope or vertigo, the psychotic group had significantly higher VBR. The schizophreniform subgroup also had significantly higher VBR than the control group minus subjects with vertigo or syncope. In the schizophreniform subgroup, positive symptoms and illness severity were associated with smaller VBR. There was no association between negative symptoms and VBR.

Adolescent↗
PubMed1992

The role of somatic mutation in the pathogenic anti-DNA response.

Anti-DNA antibodies represent a significant autospecificity in systemic lupus erythematosus because they are essentially diagnostic of the disease and they contribute to renal pathology. The molecular genetic characterization of these antibodies from both lupus-prone mice and humans with lupus has shown them to be somatically mutated. In many cases the nature of the mutations suggests that DNA or some structurally homologous molecule is driving the response. In other cases the high replacement-to-silent mutation ratio in framework regions of the antibody suggests selection by idiotype or by some mechanism other than antigen itself. Current studies of immunoglobulin variable region genes encoding anti-DNA antibodies reveal no disease associated polymorphisms. There are also no data suggesting that the nature of the recombination process that forms intact variable region genes or of the process of somatic mutation differs in autoimmune and nonautoimmune strains or kindred. Current data suggest, rather, that a defect in regulation is responsible for auto-antibody production in SLE. The finding that most if not all anti-double stranded DNA antibodies are somatically mutated suggests the defect is in maintenance of peripheral rather than central tolerance.

Animals↗
PubMed1992

TNF in combination with GM-CSF enhances the differentiation of neonatal cord blood stem cells into dendritic cells and macrophages.

We describe dendritic cell progenitors within the CD34+ stem cell compartment in neonatal cord blood and identify growth factors contributing to their differentiation. Granulocyte-macrophage colony-stimulating factor (GM-CSF), although mainly promoting the growth and differentiation of monocyte-macrophages (mono-m psi s), also induced the differentiation of cells with the distinctive morphological features of dendritic cells (DCs). Tumor necrosis factor (TNF) in combination with GM-CSF promoted further growth of both cell types but most notably increased the DC content. In situ analysis revealed that the cells exhibiting DC morphology were positive for class II major histocompatibility complex antigens but were CD14 negative, did not exhibit nonspecific esterase activity, and were nonphagocytic. Moreover, the mixed leukocyte reaction stimulatory capacity of cultures with the higher DC content was greater. TNF, interleukin-1 (IL-1), IL-6, or platelet-derived growth factor (PDGF) was inactive in promoting stem cell proliferation or DC morphology. IL-1 or PDGF synergized with GM-CSF to increase mono-m psi-associated cell proliferation but did not increase the DC content. The development of a common DC-monocyte precursor was suggested by the presence of colony-forming unit-like clusters containing mono-m psi s and DCs and one sharp proliferative peak. The loss of DC morphology after 21 days, coupled with increases in mono-m psi-associated markers and a constant number of viable cells, further suggests that DC morphology may fluctuate in culture or is a transient feature acquired by certain cells of the mono-m psi lineage.

Cell Differentiation↗
PubMed1992

Autoimmune demyelination in transgenic E alpha d-positive A.CA mice. Comparison with E-negative A.CA mice.

A body of literature exists implicating the major histocompatibility complex class II E molecule in development of immune tolerance and/or immunosuppression. To define better the regulatory mechanisms underlying susceptibility to experimental autoimmune encephalomyelitis, an autoimmune condition displaying major histocompatibility complex-II dependence, disease was induced in transgenic mice expressing a major histocompatibility complex-II E alpha d-transgene. This was compared with experimental autoimmune encephalomyelitis induced in age-matched E-negative, non-transgenic mice of the same strain. The results showed that experimental autoimmune encephalomyelitis could be induced by adoptive transfer methodology in both transgenic and non-transgenic mice of the A.CA (H-2f) strain. Virtually no differences were observed between the two mouse types with regard to disease onset, course, and neuropathology. The main difference noted was within nonirradiated recipient subgroups where the nonirradiated transgenic A.CA mice demonstrated greater inflammation and demyelination than the nonirradiated, non-transgenic mice throughout the disease course. Thus, the results did not support the idea that the E molecule, per se, is involved in the induction of tolerance or immunosuppressive mechanisms protecting against autoimmunity. In addition, histologic changes in the central nervous system of the A.CA strain, both transgenic and non-transgenic, differed in several respects from the changes observed in other more commonly studied susceptible strains. In A.CA mice, polymorphonuclear cells were a more prominent component of the acute inflammatory infiltrate and in chronic disease, large aggregates of lipid-laden macrophages and cholesterol clefts were present within white matter lesions. The present approach, using genetic manipulation of the immune system, may have relevance to the study of disease mechanisms in other putative autoimmune demyelinating disorders such as multiple sclerosis.

Animals↗