Search PubMed⌕ Search

Biomedical subjects

J N Whitaker

Publications and source records attributed to J N Whitaker.

At least 181 records · Page 10Linked to original sources
PubMed1980

Immunosuppressive agents in corticosteroid-refractory childhood dermatomyositis.

Five patients with childhood dermatomyositis, followed for 18 to 96 months, improved when treated with a combination of corticosteroids and methotrexate (one patient) or corticosteroids and cyclophosphamide (four patients) after having become refractory to corticosteroid therapy alone. Complications of vascular involvement in childhood dermatomyositis or from immunosuppressive therapy were observed in most of these patients. Disease components involving skin, muscle, or systemic vessels sometimes varied independently in regard to disease activity or therapeutic responsiveness. In two patients with stable or improving muscle function, cerebrovascular complications occurred. Monitoring of disease activity was best accomplished by clinical evaluation; serum muscle enzymes usually failed to rise prior to or during periods of clinical worsening.

Child↗
PubMed1979

Interaction of group A streptococcal lipoteichoic acid with bovine myelin basic protein.

Group A streptococcal lipoteichoic acid (LTA), a polyglycerol phosphate ester linked with fatty acids, formed precipitin lines in agar gels with the positively charged myelin basic protein (MBP) isolated from bovine brain. The LTA-MBP complexes were formed with deacylated teichoic acid and were not inhibited by monomeric glycerol phosphate, a finding indicating the participation of the polyglycerol phosphate (PGP) backbone of LTA in the reaction. Following interaction with PGP, MBP inhibited the agglutination of LTA-sensitized erythrocytes by induction of antibodies to LTA, directed against the PGP antigenic determinant. The amplification of the humoral immune response to the insoluble complex of LTA and MBP was of particular interest in view of the lack of immunogenicity of either LTA or MBP alone.

Antibody Formation↗
PubMed1978

The distribution of myelin basic protein in central nervous system lesions of multiple sclerosis and acute experimental allergic encephalomyelitis.

To obtain more information about early events in central nervous system myelin injury in multiple sclerosis (MS), a comparative study was conducted of the distribution of myelin basic protein (BP) in tissue lesions of both MS and experimental allergic encephalomyelitis (EAE). Sixteen postmortem specimens containing lesions from 4 persons with MS and the brains of 14 guinea pigs with acute EAE induced with BP were studied. Cryostat sections of quick-frozen material were fixed, treated with rabbit antibody to BP, and processed by immunoperoxidase techniques. The reaction of antibody to BP was reduced or absent in MS lesions but normal in uninvolved surrounding tissue. Alterations in BP generally paralleled changes in staining of myelin by histological methods. Marked diminution of reactivity with anti-BP occurred in early lesions of MS and extended far beyond any identifiable inflammatory elements. In both parenchyma and perivascular areas, lipid-laden macrophages in MS plaques frequently contained BP material in addition to a variable amount of endogenous peroxidatic activity. Compared with MS, BP was relatively well preserved in brains of guinea pigs with EAE. At the light microscopy level, normal-appearing patterns of BP existed adjacent to the perivascular cellular infiltrates, and macrophages containing BP material were rare. The results of this study suggest differences between MS and acute EAE in both removal of BP from the central nervous system and its subsequent disposal.

Acute Disease↗
PubMed1978

Immunochemical comparisons among myelin basic proteins.

1. The relationships among myelin encephalitogenic or basic proteins were immunochemically examined. 2. Rabbit antisera to myelin basic proteins isolated from chicken, rabbit, bovine, guinea-pig, and human brain specimens were prepared. By quantitative microcomplement fixation these rabbit antisera were used to measure cross-reactions among the myelin basic proteins of the turtle, chicken, rat, rabbit, cow, pig, sheep, dog, guinea-pig, monkey and human. 3. A spectrum of cross-reactivities was detected even though some cross-reactivity persisted across major phylogenetic barriers. Varying, but sometimes marked, differences existed in reactivities of the small and large basic proteins of the rat. Reciprocity of cross-reactivities among basic proteins was inconstant. 4. This study demonstrates the range of immunochemical cross-reactivities among myelin basic proteins and the sensitivity of quantitative microcomplement fixation in assessing such antigenic or conformational differences.

Animals↗
PubMed1978

Immunocytochemical localization studies of myelin basic protein.

The location of myelin encephalitogenic or basic protein (BP) in peripheral nervous system (PNS) and central nervous system (CNS) was investigated by immunofluorescence and horseradish peroxidase (HRP) immunocytochemistry. BP or cross-reacting material could be clearly localized to myelin by immunofluorescence and light microscope HRP immunocytochemistry. Fine structural studies proved to be much more difficult, especially in the CNS, due to problems in tissue fixation and penetration of reagents. Sequential fixation in aldehyde followed by ethanol or methanol provided the best conditions for ultrastructural indirect immunocytochemical studies. In PNS tissue, anti-BP was localized exclusively to the intraperiod line of myelin. Because of limitations in technique, the localization of BP in CNS myelin could not be unequivocally determined. In both PNS and CNS tissue, no anti-BP binding to nonmyelin cellular or membranous elements was detected.

Animals↗
PubMed1978

Quantitation of IgG, IgA and IgM in the CSF by radioimmunoassay.

A radioimmunoassay (RIA) for quantitating IgG, IgA and IgM in unconcentrated CSF has been developed. The amounts and percentages of these immunoglobulins in CSF from 31 normal individuals were determined. Using these values as normal, CSF from patients with syphilis, encephalitis, subacute sclerosing panencephalitis (SSPE), and multiple sclerosis (MS) was studied. Abnormalities were detected, indicating the potential relevance of more extensive study of the CSF immunoglobulins. CSF from patients with myotonic dystrophy and myasthenia gravis was normal. RIA was compared with rocket electroimmunodiffusion (EID) for the quantitation of IgG. Although RIA consistently gave lower absolute values, both assays reliably detect elevated IgG in CSF. However, an advantage of RIA is its capacity to quantitate IgA and IgM.

Humans↗
PubMed1977

Molecular internalization of a region of myelin basic protein.

The conformation of myelin encephalitogenic or basic protein (BP) was investigated with a double-antibody radioimmunoassay by studying the reaction of BP or its fragments with antibodies produced in two rabbits against peptide 43-88 linked to rabbit serum albumin. Both antisera reacted well with peptide 43-88 but showed little or no reaction with BP. Absorption of these antisera with a BP-immunoadsorbent did not remove the antibody activity against peptide 43-88. Within the region of peptide 43- 88 it was shown that peptides 68-88 and 79-88 gave an equivalent or better reaction than peptide 43-88, whereas peptides 43-67 and 64-73 had very little reactivity. In the BP fragments containing region 43-88, peptide 1-88 showed the best reactivity, peptide 20-166 showed minimal reactivity, while peptide 1-115 showed none. These data document the internal position of at least a portion of peptide 43-88 and all of residues 79-88 in the BP molecule. The much greater reactivity of peptide 1-88 as compared to peptide 1-115 suggests that the region or a portion of the region of BP containing residues 89- 115 participates in the conformational alignment of BP restricting access to peptide 79-88. After absorption with BP, neither of the antisera prepared to peptide 43-88 reacted with PNS myelin in fixed tissue sections but continued to react with CNS myelin in similarly treated sections. The present findings demonstrate the need to consider the role of shielded antigenic determinants in the investigation of antigens or of immune responses.

Animals↗
PubMed1977

The characterization of type I and type III collagens from human peripheral nerve.

The normal chemical features of peripheral nerve collagens were determined on postmortem, histologically normal adult human femoral nerve. 1. Genetically distinct type I, [alpha1(I)2]alpha2, and type III, [alpha1(III)]3, were isolated by differential salt precipitation and the component subunit chains, alphal(I), alpha2 and alphal(III) were obtained by ion-exchange chromatography and gel filtration. 2. The molecular weight of alphal(I) and alpha2 of type I collagen was 95 000 and that for type III was 280 000. Reduction of type III with dithiothreitol yielded expected alpha1(III) chains of 95 000 molecular weight. 3. The amino acid composition of the three collagen chains, alpha1(I), alpha2, and alpha1(III), was the same as previously reported values for the corresponding chains from human skin except for slightly elevated hydroxylysine content. 4. Peripheral nerve collagen was found to contain 81% type I collagen and 19% type III. These results indicate that peripheral nerve collagen characteristics closely simulate that of human skin and differ from that of human aorta and other parenchymal organs. These data will permit a chemical analysis for possible abnormalities of peripheral nerve collagen in various neurogenic disorders.

Aged↗