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J Silver

Publications and source records attributed to J Silver.

At least 325 records · Page 18Linked to original sources
PubMed1985

Ia antigens and susceptibility to rheumatoid arthritis.

Since the first description of human leukocyte agglutination antibodies, knowledge of the MHC, particularly the Ia region, has grown immensely and it is now recognized as a major polymorphic multigene family involved in the regulation of immune response and disease susceptibility. This review examined the hypothesis that there is another level of complexity within the Ia system, beyond multiple loci and allelic series, that involves specific epitopes as the functionally important components of the Ia molecule. Certain of these epitopes are likely to be responsible for the regulation of immune responses and susceptibility to certain autoimmune diseases such as rheumatoid arthritis (RA). Evidence was presented that certain monoclonal antibodies recognize epitopes found in a significantly more positive association with susceptibility to RA than available markers such as DR4. Biochemical characterization of the Ia molecules bearing this epitope revealed that the same epitope was present on two different molecules. The possibility was considered that such epitopes are closely related but not identical to Ia determinants that are primarily involved in producing the abnormal immune state characterizing those with RA.

Alleles↗
PubMed1985

Thy-1: a hydrophobic transmembrane segment at the carboxyl terminus.

Thy-1 is a membrane glycoprotein distributed throughout mammalian species and expressed on brain tissue and various cells of the hematopoietic lineage. The nucleotide sequences of rat and mouse Thy-1 genes revealed a similar gene organization and the existence of an extra 31 amino acid segment at the carboxyl terminus not described previously. These extra amino acids, highly conserved in both species, include a 20 amino acid hydrophobic segment at the carboxyl terminus, which may be responsible for integration of Thy-1 within the plasma membrane.

Amino Acid Sequence↗
PubMed1985

Vitamin D-dependent rickets types I and II. Diagnosis and response to therapy.

The diagnostic value of measuring serum vitamin D metabolites is demonstrated in the present study in which two patients with vitamin D-dependent rickets (VDDR) Types I and II are reported. The patient with sporadic VDDR Type I was severely disabled and unable to walk. Her serum 1,25(OH)2D level was low (32 pg/ml, normal 30 to 60) and she responded dramatically to 1 microgram of 1 alpha-hydroxyvitamin D3 daily. The VDDR Type II patient had an autosomal recessive inheritance and total alopecia. His serum 1,25(OH)2D level was greater than 500 pg/ml, compatible with end-organ refractoriness to 1,25(OH)2D. He did not respond to daily doses of 1 microgram 1 alpha-hydroxyvitamin D3. These cases demonstrate the striking difference in 1,25(OH)2D levels and therapeutic response to 1,25(OH)2D in these two conditions.

Adult↗
PubMed1985

HLA-DR4-associated haplotypes are genotypically diverse within HLA.

Biochemical diversity among products of class II HLA genes has been observed in individuals who appear to be HLA-D and DR-identical by cellular and serologic typing. We used techniques of restriction enzyme fragment analysis by Southern blotting to analyze this diversity at the level of cellular DNA. A panel of 17 HLA-DR4 homozygous cell lines (HCL) were investigated by using cDNA probes homologous to DQ beta, DQ alpha, and DR beta genes. Each probe was hybridized to cellular DNA digested with a series of different restriction endonucleases. Polymorphisms were observed with the use of the enzymes Pst I, Hind III, and Bam HI: Hybridization of cellular DNA digested with Hind III and Pst I with the DQ beta probe revealed specific polymorphisms, as did hybridization of the Pst I digest with the DQ alpha cDNA probe and the Bam HI digest with the DR beta probe. The observed differences fall into two categories: first, considerable diversity was seen between HLA-DR4 HCL that represent different HLA-D-defined haplotypes; second, diversity was also observed among HCL of the same DR4-associated HLA-D cluster. In contrast to the DQ cDNA probes, hybridization with the DR beta probe revealed relatively limited polymorphism by using a panel of different restriction endonucleases. Thus, although there is a general pattern of polymorphic restriction enzyme fragments homologous to DQ probes within an HLA-D cluster, the pattern seen for any particular cell line was not sufficiently distinct to assign an HLA-D or DR specificity.

Cell Line↗
PubMed1985

Regulation of 25-OH-D3 1 alpha-hydroxylase and 24-hydroxylase activities along the rat nephron and in isolated kidney cells.

The regulation of 25-OH-D3 metabolism in isolated cells of one kidney and microdissected single nephron segments from the contralateral kidney was studied. Preparations from rats fed a normal diet produced only 24,25-OH2-D3, in isolated cells (7.9 pmol/1.25 X 10(6) cells/min; 5 micron 25-OH-D3), in proximal convoluted tubules (PCT; 1.9 pmol/mm/min; 0.1 mM 25-OH-D3), and proximal straight tubules (PST; 1.5 pmol/mm/min; 0.1 mM 25-OH-D3). Distal tubules (DT) did not metabolize 25-OH-D3. Rats pretreated with 1,25-(OH)2-D3 produced more 24,25-(OH)2-D3 in PST (2.49 pmol/mm/min), with no change of metabolism in the isolated cells, PCT and DT. Preparations from vitamin D deficient rats produced both 24,25-(OH)2-D3 and 1,25-(OH)2-D3: 7.2 and 4.6 pmol/1.25 X 10(6) cells/min, respectively, in the cells, 0.9 and 0.3 pmol/mm/min in PCT and 1.2 and 0.4 in PST. These results confirm that rat PCT and PST have 24-hydroxylase activity, that in vitamin D deficiency, rat renal cells, PCT and PST all have both 24-hydroxylase and 1 alpha-hydroxylase activity, and that 1,25-(OH)2-D3 pretreatment increases the 24-hydroxylase activity in the PST but not in the PCT.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗
PubMed1985

Immunohistochemical analysis of human lymphomas with monoclonal antibodies to B cell and Ia antigens reactive in paraffin sections.

Monoclonal antibodies (MoAbs) to B cell- and T cell-specific antigens uniformly have been restricted in their use to cell suspension or frozen section techniques because the antigens that they identify are either masked or lost in the fixation or paraffin-embedding processes. Antiimmunoglobulin antisera, although readily identifying cytoplasmic immunoglobulin in paraffin sections, has not been as useful as originally hoped since the majority of B cell lymphomas express surface immunoglobulins, which requires cell suspensions or frozen sections for detection. Because cell suspension procedures disrupt tissue architecture and frozen section techniques grossly distort morphology, neither method allows the combination of optimal morphologic and immunologic classification of lymphomas. We recently reported two MoAbs, LN-1 and LN-2, that react with B cells in paraffin sections. LN-1 reacts with the surface membrane and cytoplasm of germinal center B cells. LN-2 reacts uniquely with the nuclear membrane and cytoplasm of mantle zone and germinal center B cells and interdigitating histiocytes. We have also identified a new MoAb, LN-3, that reacts with the HLA-DR antigen in paraffin sections. We now report the use of LN-1, LN-2, and LN-3 in the analysis of paraffin sections from 58 non-Hodgkin's lymphomas and 15 cases of Hodgkin's disease. The types of cells reactive with these MoAbs in neoplastic lymphoid proliferations largely recapitulate their benign morphologic and immunologic counterparts. As a panel, LN-1, LN-2, and LN-3 were reactive with 98% of B cell lymphomas, and LN-1 and LN-2 were negative on all T cell lymphomas. In addition to identifying the cell of origin of these malignant proliferations, these MoAbs were also useful for identifying architectural features in neoplastic lymph nodes. Thus, these reagents provide the ability to assess the immunologic phenotype of neoplastic lymphocytes in conjunction with the critical morphologic criteria requiring paraffin embedding.

Antibodies, Monoclonal↗
PubMed1984

Rat Thy-1 antigen has a hydrophobic segment at the carboxyl terminus.

We have isolated a cDNA clone coding for rat Thy-1 antigen from a rat thymocyte cDNA library. The 549 base pairs insert includes the complete coding region of a mature Thy-1 polypeptide of 142 amino acids, 31 amino acids longer than the previously reported glycoprotein sequence. These 31 amino acids contain an extremely hydrophobic region of 26 uncharged amino acids which apparently represent the transmembrane segment that allows for integration within the membrane. The presence of this additional protein segment will solve most of the enigmas regarding the properties of the C-terminal region of Thy-1 antigen.

Amino Acid Sequence↗
PubMed1984

The complexity of HLA-DS molecules. A homozygous cell line expresses multiple HLA-DS alpha chains.

Ia molecules expressed by an HLA-DRw6 homozygous cell line were immunoprecipitated with anti-Ia allosera and monoclonal antibodies and analyzed by 2-D gel electrophoresis. The DRw6 homozygous cell line was shown to express two DS beta chains; this observation extends our previous finding that a DR5 homozygous cell line expresses two DS beta chains and suggests that the expression of at least two DS beta chains by DR homozygous cell lines is a generalized phenomenon. The data presented here document for the first time that a DR homozygous cell line expresses at least two DS alpha chains. Therefore, this cell line expresses at least two DS molecules with the potential for the expression of four DS molecules. In agreement with previous reports, the cell line was shown to express two DR beta chains and one DR alpha chain that combine to form two DR molecules. The molecular specificities of two MB1 allosera and two MB1 -like monoclonal antibodies were also compared in these studies. Both MB1 allosera isolated a single DS molecule, while the MB1 -like monoclonal antibodies isolated at least two DS molecules. Therefore, these studies document for the first time that anti-Ia reagents which are specific for the MB1 or MB1 -like determinants in population studies do not recognize the same Ia molecules in immunochemical studies. The data presented here for the expression of at least two DS alpha chains and the location of the MB1 allodeterminant on only one of multiple DS molecules are in agreement with recent studies at the gene level.

Antigen-Antibody Reactions↗
PubMed1984

Studies on the factors that govern directionality of axonal growth in the embryonic optic nerve and at the chiasm of mice.

What are the forces residing at the presumptive chiasm of embryonic mice that control the directionality (i.e., side specificity) of the optic axons? In an attempt to answer this question, the overall trajectories of individual fascicles of early growing axons and the various environments that they encounter along their pathway have been charted from the eye through the nerve and into the base of the diencephalon. Serial sections and reconstructive computer graphic techniques were used for the analysis. The early optic axons (embryonic (E) day 13.5) arrive at the chiasm in a stereotyped topographic arrangement. However, the fiber array at the primitive chiasm is not retinotopically organized nor is it maintained with the same level of spatial precision as it is at the disc. Thus, the annular, inverted retinotopic contingent of "pioneering" axons that exists in the primitive nerve becomes reorganized at the chiasm into a crescent-shaped configuration, with fascicles from ventrotemporal and ventronasal retina at either side of the crescent and with fascicles from dorsal retina interposed. Because of their gross locations in the crescent, particular clusters of fibers, each largely originating from different retinal sectors, but "contaminated" with fibers from other regions, come in contact with different types of nonneuronal structures at the chiasm. One, a dense, knotlike glial formation that lies along the margin of the diencephalic-telencephalic junction, directs all adjacent (ventronasal) fibers contralaterally. The other, a discrete pathway of lengthy marginal glial processes, separated by an anastomotic system of large extracellular spaces, guides all nearby fibers from ventrotemporal retina ipsilaterally. The results suggest that fiber topography as well as local environmental factors may play important roles in guiding axons at the chiasm.

Animals↗
PubMed1984

The HLA-DR4 family of haplotypes consists of series of distinct DR and DS molecules.

Among DR4-associated HLA-D antigens, distinct and consistent structural variations were found for the products of two human "Ia-like" loci, DR and DS. Analysis of neuraminidase-treated immunoprecipitated DR molecules from 15 HLA-DR4-associated HLA-D homozygous B-lymphoblastoid cell lines by two dimensional polyacrylamide gel electrophoresis identified five distinct DR beta chains. In addition, gel analysis of immunoprecipitated DS molecules identified three distinct DS beta chains. Altogether, five distinct DR4 haplotypes were defined according to the observed structural diversity of the DR and DS beta chains. These gene products presumably contribute the dominant polymorphisms recognized by T cells in mixed lymphocyte reaction (MLR). Thus, these studies indicate that the serologic specificity known as HLA-DR4 is not a single haplotype, but a determinant present on products of individual loci arrayed into distinctly different haplotypes. These findings suggest that distinct products of individual loci, rather than conventional HLA specificities defined by alloimmune sera, may represent the genetic markers relevant to HLA-D/DR associated diseases.

Antibodies, Monoclonal↗
PubMed1984

Effects of gonadal steroids on the in vivo binding of [125I]alpha-bungarotoxin to the suprachiasmatic nucleus.

The radioligand [125I]alpha-bungarotoxin (alpha-BTX) has been used to test receptor binding to putative nicotinic cholinergic receptors in the hypothalamus. Using light microscopic autoradiography following third ventricular infusion of the radioligand we have previously demonstrated that in normally cycling rats and in normal males, the suprachiasmatic nucleus (SCN) consistently binds the alpha-neurotoxin. In chronically (5 weeks) oophorectomized female, binding of [125I]alpha-BTX to the SCN is markedly diminished. The present series of experiments were designed to test the effects of gonadal steroids on the binding of [125I]alpha-BTX to the SCN. We first tested whether or not estradiol administered to ovariectomized females could duplicate the presence of the ovary. In females ovariectomized and immediately provided with a constant dose of estradiol-17 beta (E2)--1.0 cm silastic capsules for 5 weeks, (n = 4), the binding of the neurotoxin to the SCN was maintained. In females ovariectomized for 3 weeks and replaced with E2 for 2 weeks (n = 4), the binding of [125I]alpha-BTX to the SCN was restored. In chronically (4 weeks) ovariectomized females receiving E2 for 6 days (n = 2), the binding of the neurotoxin was partially restored. We next tested the effect of chronic (5 weeks) castration (n = 100) and observed that binding of [125I]alpha-BTX to the SCN of castrated males was like that of intact male controls (n = 6).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Strong association of rheumatoid arthritis with the presence of a polymorphic Ia epitope defined by a monoclonal antibody: comparison with the allodeterminant DR4.

Among individuals with rheumatoid arthritis the presence of the polymorphic Ia antigen epitope detected by the monoclonal antibody 109d6 is more strongly correlated with disease susceptibility than are other specificities, such as HLA DR4, DRw53 (MT3) or the antigenic determinant, defined by the monoclonal antibody 17-3-3S. The cells of 93% of Caucasian and Hispanic patients react with the 109d6 reagent. As was the case in normal individuals, all DR4-positive patients express the 109d6 determinant; however, 26% of those with rheumatoid arthritis have the epitope recognized by antibody 109d6, but lack the specificity DR4. Of these, one-third expresses only HLA DR1 and DQw1 (MT1, MB1) determinants. Studies of family members reveal that here the determinants 109d6, DR1, and DQw1 are encoded by the same unusual haplotype. In certain other individuals with rheumatoid arthritis who express DR4, DRw53, and the 109d6 determinants, family studies show that the 109d6 epitope is encoded not only by the haplotype specifying DR4 but also by the opposite haplotype that does not bear the genes for DR4. This suggests that homozygosity for certain Ia epitopes is relevant to determining the disease-susceptibility state. These studies emphasize the utility of monoclonal antibodies as reagents for the recognition of Ia epitopes that are more closely involved in the determination of disease susceptibility than are allomorphic molecules detected by conventional typing alloantisera.

Antibodies, Monoclonal↗
PubMed1984

Disease susceptibility genes and the Ia system.

Certain Ia allotypes such as DR4 show a strong association with particular autoimmune diseases such as rheumatoid arthritis. Despite this strong association, a significant number of individuals with the inappropriate Ia allotype develop the disease. It is proposed that these individuals share an Ia determinant or "epitope" with individuals of the appropriate Ia allotype, and that these epitopes, which are "mobile" and can be transmitted from one Ia haplotype and/or gene locus to another by mechanisms such as gene conversion, form the molecular basis for disease-susceptibility genes.

Amino Acid Sequence↗
PubMed1984

Abnormal quinidine binding in survivors of prehospital cardiac arrest.

Quinidine binding was studied in 15 survivors of prehospital cardiac arrest and was compared to 18 normal individuals and 20 patients with coronary artery disease. The unbound quinidine fraction was 6.3 +/- 2.8% in the survivors of prehospital cardiac arrest, a value significantly lower than normal individuals (unbound quinidine fraction = 9.9 +/- 3.0%, p less than 0.005). Furthermore, unbound quinidine fraction correlated with interdose quinidine half-life in the six survivors of prehospital cardiac arrest where this could be measured (r = 0.79, p less than 0.05). The resultant quinidine interdose half-life was significantly prolonged (10 +/- 3 hours) when compared to normal (6 +/- 2 hours, p less than 0.02). The reduction in free drug fraction in cardiac arrest survivors was a nonspecific finding in that free drug fraction was also reduced in the patients with coronary artery disease (unbound quinidine fraction = 7.4 +/- 3%) and was independent of the alpha-1-glycoprotein concentration. Therefore survivors of prehospital cardiac arrest have a mean 40% reduction in free quinidine drug fraction which results in less free drug at any given total drug concentration and may relate to quinidine pharmacokinetics and pharmacodynamics in this patient group.

Blood Proteins↗
PubMed1984

Guidance of optic axons in vivo by a preformed adhesive pathway on neuroepithelial endfeet.

Antibodies against the neural cell adhesion molecule (NCAM) were used in vivo both to localize NCAM antigenic determinants in developing tissues of the chicken visual system and to perturb cell-cell adhesion during growth of optic fibers to the tectum. The immunohistochemical studies revealed a staining pattern on neuroepithelial cells which coincided with certain regions of the presumptive route for optic axons, not only with respect to the overall pathway from the eye to the tectum, but also in the preferential distribution of the antigen on the marginal endfeet which are contacted by optic axon growth cones. The antibody-perturbation studies, which involved intraocular injection of anti-NCAM Fab at embryonic Day 3.5, demonstrated that inhibition of NCAM-mediated adhesion results in a dramatic distortion of growth cone-neuroepithelial cell relationships and consequently of the optic pathway. Together, these studies suggest that guidance of optic axons along the margin of the brain is at least in part influenced by a preformed adhesive pathway on neuroepithelial cells associated with NCAM antigens.

Animals↗
PubMed1984

Development and aging of the eye in mice with inherited optic nerve aplasia: histopathological studies.

We have examined the morphological development of optic nerve aplasia in a subpopulation (10-20%) of anophthalmic mice (Strain ZRDCT -AN) that develop microphthalmia. During embryonic stages the optic fissure in microphthalmic mutants did not involute into the optic stalk. Even in the absence of a proper fissure, early differentiation of the various retinal elements was not disturbed. Subsequently, however, the optic nerve fibers failed to exit from the eye in their appropriate position. Secondary changes in the retina, probably resulting from a failure of optic axons to reach their central targets, were near total loss of ganglion cells and variable attenuation of the other nuclear and plexiform layers. Retinal rosettes were also commonly present.

Age Factors↗
PubMed1984

Expression of the Thy-1 glycoprotein gene by DNA-mediated gene transfer.

We isolated a gene encoding the Thy-1.2 glycoprotein from a recombinant library constructed from BALB/c mouse DNA. To evaluate the expression of this cloned gene in different genomic environments, we introduced it into cell lines derived from fibroblast, lymphoid, and neuronal tissues by DNA-mediated gene transfer. When integrated into the genome of mouse L cells, cell-surface Thy-1 can be detected with anti-Thy-1 monoclonal antibodies. These L-cell lines contain between two and four copies of the cloned Thy-1 gene stably integrated in the host genome. After subcloning into a plasmid vector containing the bacterial Eco-gpt gene as a selectable marker, the Thy-1 gene was introduced into the Thy-1-deficient mouse lymphoma AKR1 (Thy-1-d), and the rat neuronal cell line, B50. The resulting transformants also contain two to four copies of the cloned Thy-1 gene but express up to 50-fold more cell-surface Thy-1.2 than the L cell transformants. The expression of vastly differing amounts of cell-surface Thy-1 from similar numbers of genes suggests that the gene encoding this differentiation antigen is under tissue-specific regulation.

Animals↗