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D J Miller

Publications and source records attributed to D J Miller.

At least 109 records · Page 6Linked to original sources
PubMed1996

Immunoglobulins reactive with myelin basic protein promote CNS remyelination.

We tested the hypothesis that immunoglobulins directed against a CNS autoantigen, myelin basic protein, may promote remyelination in the course of a chronic, immune-mediated demyelinating disease. SJL/J mice infected chronically with Daniel's strain of Theiler's virus served as an experimental model of MS. The spinal cords of these mice exhibit extensive primary demyelination and inflammation with minimal spontaneous remyelination. Treatment with whole antiserum or affinity-purified mouse immunoglobulins directed against rat or rabbit myelin basic protein increased new myelin synthesis as measured by quantitative morphometry. Electron microscopy revealed numerous oligodendrocytes in remyelinated CNS lesions and a relative lack of inflammatory cells. Viral antigen persisted in the spinal cord despite enhanced CNS-type remyelination. These findings indicate that immunoglobulins reactive with myelin autoantigens have the potential to promote myelin repair.

Animals↗
PubMed1996

Breastfeeding practices among resident physicians.

OBJECTIVE: To determine how employment as a resident physician (resident) affects breastfeeding practices and experiences. DESIGN: Cross-sectional questionnaire survey. SETTING: US resident physicians in the second half of their postgraduate year three (PGY3). PARTICIPANTS: 1500 questionnaires were mailed at random to female 1990 graduates of American medical schools. After eliminating unusable surveys, an adjusted response rate of 45% produced 450 surveys; 60 delivered a child during residency. INTERVENTIONS: None. MEASUREMENT/MAIN RESULTS: Forty-eight (80%) of 60 residents who delivered initiated breastfeeding, and continued for the duration of their maternity leave (mean, 7 weeks). With a return to residency half (24) of those who had initiated breastfeeding discontinued breastfeeding. The breastfeeding rate dropped to 15% (9/60) at 6 months. Residency work schedule was the most common reason (80%) for discontinuing breastfeeding. Of the 24 residents who continued breastfeeding while working, 83% pumped breast milk during their work shifts; 79% felt there was insufficient time during work, and 42% reported no appropriate place at work to express milk. Only 54% who continued felt supported by their attending physicians for their efforts to breastfeed; 67% felt colleagues were supportive. CONCLUSIONS: The breastfeeding initiation rate for resident mothers was in compliance with the Healthy People 2000 guidelines, but the rate at infant age 6 months fell well below the goal of 50%. Modifiable factors in residents' work sites include both physical and emotional accommodations to encourage resident mothers to breastfeed.

Adult↗
PubMed1995

Oligodendrocyte-reactive O1, O4, and HNK-1 monoclonal antibodies are encoded by germline immunoglobulin genes.

Natural or physiologic autoantibodies are present normally in serum, are polyreactive, are frequently of the IgM subtype, and are encoded by unmutated germline genes. We tested whether the oligodendrocyte-reactive O1, O4, A2B5, and HNK-1 IgM kappa monoclonal antibodies are natural autoantibodies by sequencing immunoglobulin (Ig) cDNAs and comparing these with published germline sequences. O1 VH was identical with unrearranged VH segment transcript A1 and A4. O4 VH had three and HNK-1 VH had six nucleotide differences from germline VH101 in the VH coding region. The D segment of O1 was derived from germline SP2 gene family. The D segments of O4 and HNK-1 were derived from DFL16 gene family. O4 JH and HNK-1 JH were encoded by unmutated germline JH4, whereas O1 JH was encoded by germline JH1 with one silent nucleotide change. O1 and O4 light chains were identical with myeloma MOPC21 except for one silent nucleotide change. HNK-1 V kappa was identical with germline V kappa 41 except for two silent nucleotide changes. O1 J kappa, O4 J kappa and HNK J kappa were encoded by unmutated germline J kappa 2. In contrast, A2B5 VH showed seven nucleotide differences from germline V1, whereas no germline sequence encoding A2B5 V kappa was identified. O1 and O4, but not A2B5 were polyreactive against multiple antigens by direct ELISA. Therefore, O1, O4 and HNK-1 Igs are encoded by germline genes, and have the genotype and phenotype of natural autoantibodies.

Amino Acid Sequence↗
PubMed1995

Spontaneous and induced remyelination in multiple sclerosis and the Theiler's virus model of central nervous system demyelination.

Remyelination in the central nervous system, originally thought to occur rarely, if ever, is now an established phenomena in multiple sclerosis patients. However, the extent of myelin repair is incomplete and limited. Experimental models of central nervous system demyelination provide an opportunity to study the cellular and molecular events involved in remyelination. These models may provide some clue to why remyelination in multiple sclerosis is incomplete as well as suggest potential methods to stimulate central nervous system repair. In this review we examine the morphological aspects of central nervous system remyelination and discuss both spontaneous and induced remyelination in multiple sclerosis and experimental models of central nervous system demyelination. We give special emphasis to the Theiler's virus model of central nervous system demyelination and its usefulness to identify therapeutic agents to promote remyelination. The role of immunoglobulins in promoting remyelination in both the Theiler's model system and in multiple sclerosis is discussed. Finally, we examine the potential physiological role of demyelination and remyelination and its relationship with clinical manifestations of central nervous system disease.

Animals↗
PubMed1995

Activation of a G protein complex by aggregation of beta-1,4-galactosyltransferase on the surface of sperm.

Fertilization is initiated by the species-specific binding of sperm to the extracellular coat of the egg. One sperm receptor for the mouse egg is beta-1,4-galactosyltransferase (GalTase), which binds O-linked oligosaccharides on the egg coat glycoprotein ZP3. ZP3 binding induces acrosomal exocytosis through the activation of a pertussis toxin-sensitive heterotrimeric guanine nucleotide-binding protein (G protein). The cytoplasmic domain of sperm surface GalTase bound to and activated a heterotrimeric G protein complex that contained the Gi alpha subunit. Aggregation of GalTase by multivalent ligands elicited G protein activation. Sperm from transgenic mice that overexpressed GalTase had higher rates of G protein activation than did wild-type sperm, which rendered transgenic sperm hypersensitive to their ZP3 ligand. Thus, the cytoplasmic domain of cell surface GalTase appears to enable it to function as a signal-transducing receptor for extracellular oligosaccharide ligands.

Acrosome↗
PubMed1995

The relationship between the adrenoceptor and nonadrenoceptor-mediated effects of imidazoline- and imidazole-containing compounds.

This article brings together work on imidazoline or imidazole-containing compounds concerned with the pharmacology of alpha-adrenoceptors, principally on smooth muscle, to illustrate how imidazolines have contributed to the subclassification of alpha-adrenoceptors and how, against this background, attempts have been made to use this knowledge to uncover "nonadrenoceptor"-mediated biological effects of previously uncharacterized compounds, notably imidazole-containing dipeptides and "clonidine displacing substance" (CDS). Recent data are included on (1) the pharmacology of UK-14304, (2) nonadrenoceptor actions of phentolamine, (3) the pharmacology of tissue extracts containing imidazole-containing dipeptides and CDS activity, and (4) ligand binding data at I1 and I2 sites.

Animals↗
PubMed1995

Experimental strategies to promote central nervous system remyelination in multiple sclerosis: insights gained from the Theiler's virus model system.

The destruction of central nervous system (CNS) myelin, the lipid-rich insulator surrounding axons in the mammalian brain and spinal cord, is the primary pathological finding in multiple sclerosis. Myelin loss can result in a significant clinical deficit, and was originally thought to be permanent, similar to axonal destruction. However, myelin regeneration is now an established phenomenon in both human disease and animal models of CNS demyelination. In this review, the concept of remyelination in demyelinating diseases such as multiple sclerosis is discussed and the usefulness of animal models of CNS demyelination in developing experimental strategies to promote remyelination is examined. Special emphasis is given to the Theiler's murine encephalomyelitis model, which has been the primary animal model used to investigate therapies designed specifically to stimulate myelin repair.

Animals↗
PubMed1995

A monoclonal autoantibody that promotes central nervous system remyelination in a model of multiple sclerosis is a natural autoantibody encoded by germline immunoglobulin genes.

Antibodies directed against self-Ags are frequently considered detrimental, and have been shown to play a pathogenic role in certain autoimmune diseases. However, the presence of autoreactive Abs in normal individuals suggests that some autoantibodies could participate in normal physiology. Our previous studies demonstrated that monoclonal autoantibodies SCH94.03 and SCH94.32, generated from the splenocytes of uninfected SJL/J mice injected with normal homogenized spinal cord, promote central nervous system remyelination when passively transferred into syngeneic mice chronically infected with Theiler's murine encephalomyelitis virus, an established experimental model of multiple sclerosis. In this study we show that these two monoclonal autoantibodies are identical, and have phenotypic characteristics of natural autoantibodies. By using a solid phase assay system, SCH94.03 and SCH94.32 showed reactivity toward several protein Ags and chemical haptens, with prominent reactivity toward spectrin, (4-hydroxy-3-nitrophenyl)acetyl, and fluorescein. Sequence analysis showed that both SCH94.03 and SCH94.32 were encoded by identical germline Ig light chain V kappa 10/J kappa 1 and heavy chain V23/DFL16.1/JH2 genes, with no definitive somatic mutations. These results indicate that a natural autoantibody participates in a beneficial physiologic response to central nervous system injury.

Amino Acid Sequence↗
PubMed1995

Systematic relationships within the Anthozoa (Cnidaria: Anthozoa) using the 5'-end of the 28S rDNA.

Systematic relationships among the subclasses of Anthozoa, and especially among the orders Scleractinia, Actiniaria, and Corallimorpharia of subclass Zoantharia, were investigated by applying parsimony and distance methods of analysis to nucleotide sequence data obtained for the 5' end of the 28S rDNA. Exhaustive parsimony analysis indicates that the Ceriantipatharia are most representative of the ancestral Anthozoa. When applied to a wide range of scleractinians (nine taxa), actiniarians (seven taxa), and corallimorpharians (six taxa), both parsimony and distance analyses resolve three groups, one being the Scleractinia and the others containing both actiniarians and corallimorpharians. This indicates an unclear relationship between Actiniaria and Corallimorpharia and gives no support for Hand's hypothesis of scleractinian ancestry of actiniarians and corallimorphians; the monophyly of the Scleractinia, which is strongly supported by our analyses, is evidence to the contrary.

Animals↗
PubMed1995

Interactions of myelin basic protein with palmitoyllysophosphatidylcholine: characterization of the complexes and conformations of the protein.

The stoichiometry of palmitoyllysophosphatidylcholine/myelin basic protein (PLPC/MBP) complexes, the location of the protein in the lysolipid micelles, and the conformational changes occurring in the basic protein and peptides derived from it upon interaction with lysolecithin micelles were investigated by circular dichroic spectropolarimetry, ultracentrifugation, electron paramagnetic resonance (EPR) and 31P, 13C, and 1H nuclear magnetic resonance spectroscopy (NMR), and electron magnetic resonance spectroscopy (NMR), and electron microscopy. Ultracentrifugation measurements indicated that well-defined complexes were formed by the association of one protein molecule with approximately 141 lysolipid molecules. Small-angle X-ray scattering data indicated that the PLPC/MBP complexes form particles with a radius of gyration of 3.8 nm. EPR spectral parameters of the spin labels 5-, and 16-doxylstearate incorporated into lysolecithin/basic protein aggregates, and 13C- and 1H-NMR relaxation times of PLPC indicated that the addition of the protein did not affect the environment and location of the labels and the organization of the lysolipid micelles. The data suggested that MBP lies primarily near the surface of the micelles, with segments penetrating beyond the interfacial region into the hydrophobic interior, but without any part of the protein being protected against rapid exchange of its amide groups with the aqueous environment. The basic protein acquired about 20% alpha-helix when bound to lysolipid micelles. Circular dichroic spectra of sequential peptides derived by cleavage of the protein revealed the formation of alpha-helical regions in the association with lysolecithin. Specific residues in myelin basic protein that participated in binding to the micelles were identified from magnetic resonance data on changes in the chemical shifts and intensities of assigned resonances, and line broadening of peaks by fatty acid spin-labels incorporated into the micelles.

Animals↗
PubMed1995

Characterization of a novel non-muscle myosin-related protein from Onchocerca gibsoni.

A cDNA library was constructed in lambda gt11 using poly(A)+ mRNA from early larvae of Onchocerca gibsoni. Screening of the library using serum from a single onchocerciasis patient yielded several strongly immunoreactive clones, one of which (OGK2) was found to encode a novel myosin-related protein. cDNA clone OGK2 contained an insert of 2017 bp, consisting of continuous open reading frame in frame with the vector, hence this clone encodes 671 amino acid residues of a larger protein. A fragment (619 nt) of the OGK2 cDNA was subcloned into the expression vector pGEX-1N to generate a glutathione S-transferase fusion protein. Polyclonal antiserum raised to this fusion protein strongly recognised an O. gibsoni protein of approximately 220 kDa. Immunolocalization studies indicated that this protein was associated predominantly with the hypodermis and a number of other specific membrane layers in the adult parasite. Myosin-related proteins are frequently immunodominant parasite antigens and in a number of studies have been shown to confer a degree of protective immunity against the corresponding parasite. Evaluation of the protective potential of the OGK2 protein, therefore, appears to be warranted.

Amino Acid Sequence↗
PubMed1995

Elevator talk: observational study of inappropriate comments in a public space.

OBJECTIVES: We conducted a study to determine the type and frequency of inappropriate comments made by hospital employees while riding hospital elevators. METHODS: Four observers rode in elevators at five hospitals, listening for any comments made by hospital employees that might be deemed inappropriate. All potentially inappropriate comments were reviewed by the research team and were classified as inappropriate if they met at least one of the following criteria: violated patient confidentiality, raised concerns about the speaker's ability or desire to provide high-quality patient care, raised concerns about poor quality of care in the hospital (by persons other than the speaker), or contained derogatory remarks about patients or their families. RESULTS: We observed 259 one-way elevator trips offering opportunity for conversation. We overheard a total of 39 inappropriate comments, which took place on 36 rides (13.9% of the trips). The most frequent comments (18) were violations of patients confidentiality. Next most frequent (10 comments) were unprofessional remarks in which clinicians talked about themselves in ways that raised questions about their ability or desire to provide high-quality patient care. Other comments included derogatory statements about the general quality of hospital care (8) and derogatory remarks about patients (5). Physicians were involved in 15 of the comments, nurses in 10, and other hospital employees in the remainder. CONCLUSION: Inappropriate comments took place with disturbing frequency in the elevator rides we sampled. These comments did not exclusively involve violations of patient confidentiality, but encompassed a range of discussions that health care employees must be careful to avoid.

Confidentiality↗
PubMed1995

Effect of age on fever response to recombinant interleukin-6 in a murine model.

BACKGROUND: A blunted or absent fever response to infection may occur in elderly people. Fever is mediated by endogenously produced molecules of leukocytes. The best studied of these molecules is interleukin-1 (IL-1). However, interleukin-6 (IL-6) is also known to possess the biological properties of pyrogenic cytokines. In this study, we assessed the influence of age on the febrile response to recombinant IL-6 (rIL-6) using a well-defined murine model. METHODS: Balb/c male mice were injected intravenously and intraperitoneally with varying doses of rIL-6. Control mice received pyrogen-free phosphate buffered saline. Temperatures were measured rectally at baseline and at 10-minute intervals for 120 minutes post-injection using a thermistor probe. Stable baseline temperatures were first determined, and post-injection temperatures were recorded every 10 minutes for up to 120 minutes. RESULTS: A dose-response correlation was found between the amount of the injected rIL-6 and the mean temperature changes in both young and old mice. The mean temperature changes for both young and old mice were higher following a 25 ng dose compared to a 12.5 ng dose of rIL-6 injected intravenously, and, likewise, following a 500 ng dose compared to a 250 ng dose of rIL-6 injected intraperitoneally. A significant delay in the peak temperature response was seen for both young and old mice when comparing intraperitoneal injections to intravenous injections. However, control mice showed no changes. CONCLUSIONS: Our findings confirm that IL-6 has a role in the pathogenesis of fever and that aging alters the febrile response to rIL-6.

Aging↗
PubMed1995

Immunological studies on an Onchocerca volvulus intermediate-filament protein.

We report the complete sequence of the cDNA encoding an intermediate filament (IF) protein from Onchocerca volvulus. The OVIF cDNA encodes a protein of 613 amino acid residues, which has a predicted molecular weight of approximately 70 kD. The size of the protein encoded by the OVIF cDNA corresponds well with estimates obtained in Western blotting experiments, but these same experiments suggest that Onchocerca sp. may contain at least two IF proteins. To identify the domain(s) of the OVIF protein responsible for immunogenicity in human filariasis patients, fragments of the OVIF cDNA were subcloned into the appropriate pGEX vector and Western blots of the corresponding fusion proteins probed with human sera. Pooled sera from general onchocerciasis or Bancroftian filariasis patients reacted only with the C-terminal region of the OVIF protein, whereas sowda onchocerciasis sera reacted 1-2 orders of magnitude more strongly and with a number of other epitopes. Immunolocalization experiments implied that the OVIF protein is associated with both muscle and a number of specific membrane layers. These studies provide the basis for evaluation of the protective potential of the OVIF protein.

Amino Acid Sequence↗
PubMed1995

Intracellular effects of free radicals and reactive oxygen species in cardiac muscle.

Oxygen-derived free radicals (FRs) and other reactive oxygen species (ROS) have been implicated in the deleterious aspects of myocardial infarction, neutrophil infiltration and post-ischaemic reperfusion. We studied their actions on the main intracellular organelles of Ca-compartmentation and force production (the sarcoplasmic reticulum (SR) and myofilaments) in rat heart preparations by using two forms of chemical 'skinning'. We recorded Ca(2+)-activated isometric tension or, in saponin-treated trabeculae where SR function is maintained, either tension alone or tension and [Ca2+] transients evoked by caffeine. A single, brief application of xanthine/xanthine oxidase (generating superoxide; O2-) rapidly and irreversibly inhibits Ca(2+)-activated force with a dose- and time-dependent action. The kinetics of residual force production are slowed. Rigor induction (by ATP withdrawal) before and during exposure to .O2- prevents this action, suggesting the .O2(-)-sensitive site is occluded in rigor. Myofilament Ca-sensitivity and SR function were unaffected by .O2- or physiologically relevant [H2O2] (< 10 microM). Briefly applying 10-50 microM hypochlorous acid (HOCl) increased Ca-sensitivity and resting tension, but reduced Ca-activated force, in a manner consistent with 'rigor-like' crossbridges being involved. HOCl also provoked spontaneous Ca-release but reduced net SR Ca-uptake. Electron microscopy reveals that the myofilament lattice suffers a characteristic disruption by HOCl but not by .O2-. We conclude that FRs and ROS associated with myocyte dysfunction, reperfusion and inflammation could contribute to post-ischaemic myocardial dysfunction.

Animals↗
PubMed1995

Sarcoplasmic reticulum and myofilament function in chemically-treated ventricular trabeculae from patients with heart failure.

OBJECTIVES: Assessment of sarcoplasmic reticulum calcium-loading ability, myofilament force production and myofilament calcium sensitivity in ventricular trabeculae from patients with heart failure. METHODS: Right ventricular trabeculae (diameter 150-250 microns) were obtained from 18 patients undergoing elective cardiac transplantation. These were mounted for isometric tension measurement and treated with saponin which permeabilises the sarcolemma leaving the sarcoplasmic reticulum (SR) functionally intact. The trabecula was bathed in a mock intracellular solution containing ATP and weakly buffered [Ca2+] at various concentrations (150-400 nM). The amplitude of caffeine-induced contractures was used as a quantitative measure of the SR calcium content and was correlated with the clinical severity of heart failure. The same trabecula was then exposed to a solution containing Triton-X100 (1%) which destroys all cell membranes leaving only the myofilaments intact. The maximum calcium-activated force (Cmax) and myofilament responsiveness to calcium was assessed. RESULTS: Patients with ischaemic heart disease (IHD) and severe heart failure (PCWP > 20 mm Hg, ejection fraction < 15%, n = 8) demonstrated low SR Ca(2+)-loading ability compared with patients with IHD and moderate heart failure (PCWP-20 mmHg, LV ejection fraction > 20%, n = 6). Patients with dilated cardiomyopathy (DCM) (n = 4) demonstrated SR Ca(2+)-loading ability which was lower than either of the two IHD groups. Myofilament force production (per unit cross-sectional area) was not significantly different between the three groups. Myofilament responsiveness to Ca2+ demonstrated no relationship with severity of heart failure. CONCLUSIONS: In human heart failure, SR Ca(2+)-loading ability diminishes with increasing severity of heart failure. Myofilament force production and sensitivity to calcium are unaffected by severity of heart failure.

Actin Cytoskeleton↗
PubMed1995

Fatal myocardial infarction in an 8-year-old girl with systemic lupus erythematosus, Raynaud's phenomenon, and secondary antiphospholipid antibody syndrome.

An 8-year-old black girl with a 5 month history of systemic lupus erythematosus (SLE) and secondary antiphospholipid syndrome (APS) developed Raynaud's phenomenon, marked hemolytic anemia, and a fatal myocardial infarction (MI). Pathologic evaluation of the heart demonstrated a transmural acute MI associated with a recent thrombus of the circumflex coronary artery, thrombosis of small intramural arteries, and a coronary arteriopathy resembling fibromuscular dysplasia. Inflammatory or atherosclerotic changes of the coronary arteries were distinctly absent. This case represents the youngest reported patient with SLE, MI, and pathologic confirmation of nonatheromatous coronary artery disease. The observed coronary pathological findings may have accentuated the thrombogenic potential of the APS, resulting in coronary thrombosis. Cardiac lesions in SLE and APS are reviewed, and pathogenetic considerations for the coronary vasculopathy are discussed.

Anemia, Hemolytic↗