Directional couplers composed of non-Kerr-law material

The effects on propagation in directional couplers made of non-Kerr-law material are examined. Many unstable modes can exist at one input power level, in contrast to only one for Kerr-law material. Special design features are possible by tailoring the dependence of the refractive index on intensity.

Mismatched directional couplers

Various twin-core couplers composed of mismatched optical fibers are capable of complete power transfer over lengths only moderately longer than their matched analogs. Examples include tapered and piecewise-continuous mismatched couplers. These linear couplers also provide insight into the mechanism of nonlinear coupling because nonlinearity induces periodic mismatching betweén twin cores that are axially uniform.

Unification of nonlinear-optical fiber devices

Nonlinear coupling can be described in a universal form applicable to a general class of optical fiber devices involving the interaction of two modes. By knowing the solution to one type of device, we then have the solution to all other types. For example, the descriptions of birefringent fibers used as switches and amplifiers have their direct counterparts in directional (twin-core) couplers, found by merely redefining the meaning of subscripts in equations or on the phase-space portrait. The key to this unification follows, not by actually solving any one problem but rather by interrelating the coupling of normal modes with the coupling of submodes, e.g., the individual core modes of directional couplers.

T cell recognition in experimental autoimmune encephalomyelitis: prospects for immune intervention with synthetic peptides

Peptide binding and lymph node T cell activation studies have been used to characterize T cell recognition of an encephalitogenic T cell autoantigen from myelin basic protein in mice of the H-2u haplotype. An important role for MHC class II molecules in "determinant selection" is revealed. Amino acids which determine interactions with either the restriction element of the major histocompatibility complex (MHC) or the encephalitogenic T cell receptor are defined. This information enables the design of peptides which bind MHC yet do not crossreact with the autoantigen. Two such peptides compete with the autoantigen for binding to the disease associated class II molecule and inhibit induction of experimental autoimmune encephalomyelitis in H-2u mice. Prospects for peptide mediated therapy are discussed.

Prevention of experimental encephalomyelitis with peptides that block interaction of T cells with major histocompatibility complex proteins

Two synthetic immunodominant and nonencephalitogenic peptides of myelin basic protein, N1-20 and AcN9-20, effectively compete with an encephalitogenic peptide, AcN1-11, in an in vitro T-cell response restricted by class II major histocompatibility complex products (I-Au). These mutant peptide constructs, which do not occur in nature, also compete with the self-antigen for the in vivo induction of T cells primed with the encephalitogen AcN1-11. By using these nonpathogenic competitor peptides, it is possible to prevent the development of a prototypic T-cell-mediated autoimmune disease, experimental allergic encephalomyelitis. These results suggest possibilities for the utilization of competitor peptides for therapy of T-cell-mediated autoimmune diseases linked to specific major histocompatibility complex genes.

Antigen recognition in autoimmune encephalomyelitis and the potential for peptide-mediated immunotherapy

Peptide binding and lymph node T cell activation studies have been used to characterize T cell recognition of an encephalitogenic T cell autoantigen from myelin basic protein in (PL/J x SJL)F1 mice. Amino acids that determine interactions with either the restriction element of the major histocompatibility complex (MHC) or the encephalitogenic T cell receptor are defined. This information enables the design of peptides that bind MHC yet do not cross-react with the autoantigen. A peptide analog of the encephalitogenic epitope is shown to be "heteroclitic" for MHC binding and activation of encephalitogenic T cells in vitro. This analog is not immunogenic for encephalitogenic T cells in vivo and is shown to inhibit disease that is induced by the autoantigen itself.

Modes of nonlinear couplers: building blocks for physical insight

The physics of nonlinear couplers is dictated by its normal modes, modes that are found from linear (axially uniform) couplers. Elementary power-flow arguments establish whether the mode is stable or unstable. These facts provide the bifurcation diagram that fully characterizes nonlinear coupling.

Description of nonlinear couplers by power conservation

Poynting's vector theorem describes power flow on twin-core couplers with arbitrary axial perturbations, both linear and nonlinear. This bypasses the coupled amplitude formulation and unifies nonlinear two-mode interactions in general.

Polymorphic residues on the I-A beta chain modulate the stimulation of T cell clones specific for the N-terminal peptide of the autoantigen myelin basic protein

The effect of polymorphic residues on the A alpha A beta molecule on T cell recognition of the N-terminal nonapeptide of myelin basic protein (R1-9) was determined. Ak-restricted T cell clones recognizing R1-9 were isolated. The peptide-Ia specificities of these clones were determined by testing the response to 1) a panel of peptide analogs of R1-11, 2) splenic APC from mice expressing MHC molecules from serologically distinct haplotypes, and 3) L cell transfectants expressing mutant/recombinant A beta cDNA containing combinations of polymorphic nucleotide sequences from the k and u alleles. Comparisons were made between the Ak-restricted clones and a previously characterized panel of Au-restricted clones. Certain Ak-restricted clones were able to recognize MBP peptide analogs that were not recognized by any of the Au-restricted clones. The Au-restricted T cell clones did not cross-react with R1-9 presented in the context of Ak, whereas the majority of the Ak-restricted clones responded to R1-9 presented in the context of Au. This nonreciprocal cross-reactivity was also reflected in the relative responses of the two sets of T cell clones to the interchange of u- and k-derived residues in the A beta chain. Residues in regions corresponding both the alpha-helical or beta-sheet portions of the hypothetical Ia three-dimensional structure were involved. The results suggest that overall specificity of the T cell clones is the summation of numerous distinct subspecificities for different regions of the peptide-Ia ligand. These results indicate that there can be striking differences in T cell specificity for an autoantigenic epitope, even in the context of A alpha A beta molecules from very closely related haplotypes.

Polymorphic residues on the I-A beta chain modulate the stimulation of T cell clones specific for the N-terminal peptide of the autoantigen myelin basic protein

The effect of polymorphic residues on the A alpha A beta molecule on T cell recognition of the N-terminal nonapeptide of myelin basic protein (R1-9) was determined. Ak-restricted T cell clones recognizing R1-9 were isolated. The peptide-Ia specificities of these clones were determined by testing the response to 1) a panel of peptide analogs of R1-11, 2) splenic APC from mice expressing MHC molecules from serologically distinct haplotypes, and 3) L cell transfectants expressing mutant/recombinant A beta cDNA containing combinations of polymorphic nucleotide sequences from the k and u alleles. Comparisons were made between the Ak-restricted clones and a previously characterized panel of Au-restricted clones. Certain Ak-restricted clones were able to recognize MBP peptide analogs that were not recognized by any of the Au-restricted clones. The Au-restricted T cell clones did not cross-react with R1-9 presented in the context of Ak, whereas the majority of the Ak-restricted clones responded to R1-9 presented in the context of Au. This nonreciprocal cross-reactivity was also reflected in the relative responses of the two sets of T cell clones to the interchange of u- and k-derived residues in the A beta chain. Residues in regions corresponding both the alpha-helical or beta-sheet portions of the hypothetical Ia three-dimensional structure were involved. The results suggest that overall specificity of the T cell clones is the summation of numerous distinct subspecificities for different regions of the peptide-Ia ligand. These results indicate that there can be striking differences in T cell specificity for an autoantigenic epitope, even in the context of A alpha A beta molecules from very closely related haplotypes.

Root Tissue Response of Two Related Soybean Cultivars to Infection by Lectin-treated Meloidogyne spp

Treatment of second-stage juveniles (J2) of Meloidogyne incognita race 1 and M. javanica with soybean agglutinin, Concanavalin A, wheat germ agglutinin, Lotus tetragonolobus agglutinin, or Limax flavus agglutinin or the corresponding competitive sugars for each of these lectins did not alter normal root tissue response of soybean cultivars Centennial and Pickett 71 to infection by M. incognita race 1 or M. javanica. Giant cells were frequently induced in Centennial and Pickett 71 roots 5 and 20 days after inoculation of roots with untreated J2 of a population of M. incognita race 3. Treatment of J2 of M. incognita race 3 with the lectins or carbohydrates listed above caused Centennial, but not Pickett 71, root tissue to respond in a hypersensitive manner to infection by M. incognita race 3. Penetration of soybean roots by J2 of Meloidogyne spp. was strongly inhibited in the presence of 0.1 M sialic acid. Treatment of J2 with sialic acid was not lethal to nematodes, and the inhibitory activity of sialic acid was apparently not caused by low pH. These results suggest that carbohydrates may influence plant-nematode interactions.

Pseudotumor cerebri and macular disease

The most common indications for treatment of patients with pseudotumor cerebri are the presence of severe intractable headaches and evidence of optic neuropathy. The role of the ophthalmologist in following patients with pseudotumor cerebri has been to document optic nerve dysfunction in terms of visual field abnormalities or loss of visual acuity. Macular changes have been described in association with papilledema. A case of pseudotumor cerebri and associated macular disease is reviewed to call attention to the need for the ophthalmologist to differentiate between visual loss secondary to optic neuropathy from that of macular disease. The case illustrates how quickly macular disease can develop. The management of patients with pseudotumor cerebri is discussed.

Involvement of distinct murine T-cell receptors in the autoimmune encephalitogenic response to nested epitopes of myelin basic protein

The peptide p89-101 (Val-His-Phe-Phe-Lys-Asn-Ile-Val-Thr-Pro-Arg-Thr-Pro) of myelin basic protein is encephalitogenic in mice expressing H-2q and H-2s antigens. Six of 13 encephalitogen-specific T-cell clones were shown to express the variable beta-chain (V beta) 17a gene product (KJ23a+), whereas seven clones were KJ23a-. Both KJ23a+ and KJ23a- subpopulations were encephalitogenic in SJL/J mice when adoptively transferred. Depletion of KJ23a+ cells in vivo with the administration of the antibody KJ23a suppresses experimental allergic encephalomyelitis induced with KJ23a+ T-cell lines. However, experimental allergic encephalomyelitis induced with either (i) encephalitogenic peptide p89-101, (ii) intact myelin basic protein, or (iii) KJ23a- T cells reactive to p89-101 cannot be prevented with monoclonal antibody KJ23a. These data indicate that in spite of the V beta 17a gene expression in a relatively large proportion of p89-101-specific T cells, such V beta gene use is not essential for the induction of experimental allergic encephalomyelitis in SJL/J mice. These results contrast with the predominance of V beta gene use (V beta 8.2) in T cells reactive to the encephalitogenic fragment (pR1-11) in PL/J mice. One reason for this lack of dominant use of a particular T-cell receptor V beta gene family in the autoimmune response to myelin basic protein in SJL/J mice stems from the observation that two encephalitogenic epitopes exist in p89-101. KJ23a- T cells are stimulated by the deleted peptide p89-100, whereas KJ23a+ T cells are not. Thus, in the response to an encephalitogenic fragment of myelin basic protein containing two nested epitopes, at least two distinct T-cell receptor V beta genes are expressed. These distinct T-cell subpopulations can each trigger experimental allergic encephalomyelitis. These findings have implications for therapy of autoimmune disease with antibodies to the T-cell receptor gene products.

Characterization of Carbohydrates on the Surface of Second-stage Juveniles of Meloidogyne spp

Fluorescent conjugates of the lectins soybean agglutinin (SBA), Concanavalin A (Con A), wheat germ agglutinin (WGA), Lotus tetragonolobus agglutinin (LOT), and Limulus polyphemus agglutinin (LPA) bound primarily to amphidial openings and amphidial secretions of viable, preinfective second-stage juveniles (J2) of Meloidogyne incognita races 1 and 3 (Mil, Mi3) and M. javanica (Mj). No substantial difference in fluorescent lectin binding was observed among the populations examined. Binding of only LOT and LPA were inhibited in the presence of 0.1 M competitive sugar. Structural differences in amphidial carbohydrate complexes among populations of Mi 1, Mi3, and Mj were revealed by glycohydrolase treatment of preinfective J2 and subsequent labeling with fluorescent lectins. A quantitative microfiltration enzyme-linked lectin assay revealed previously undetected differences in lectin binding to nonglycohydrolase-treated J2. Freinfective J2 of Mj bound the greatest amount of SBA, LOT, and WGA, whereas J2 of Mil bound the most LPA.

Successful treatment of EAE in rhesus monkeys with MHC class II specific monoclonal antibodies

Experimental Allergic Encephalomyelitis (EAE) was induced in rhesus monkeys by subcutaneous immunization with calfbrain homogenate in complete Freunds adjuvant. Monkeys were treated with major histocompatibility complex (MHC) Class II specific monoclonal antibodies (MoAb) as soon as the first clinical EAE signs became apparent. Two different treatments were tested. One consisted of 10 daily injections of a mixture of two MHC Class II specific MoAb, reactive with a monomorphic structure of rhesus monkey Class II molecules. The other consisted of 10 daily injections of Genox3.53, specific for HLA-DQW1. This MoAb crossreacts well with monkeys and also detects a polymorphism in this species and is presumably reactive with the RhLA-DQW1 antigen. Both MoAb treatments could modify the clinical course of EAE favourably. Untreated animals invariably died within 3 d of the onset of clinical EAE signs. Only one of the three monkeys treated with the monomorphic MHC Class II MoAb preparation died within 3 d, and the other two survived significantly longer than untreated animals. Both animals treated with Genox3.53 survived significantly longer than untreated control animals. Although only a few animals were tested, these results clearly show the possible beneficial influence of MHC Class II specific MoAb on a T-cell mediated autoimmune disease.

Evaluation of Paecilomyces lilacinus as a Biocontrol Agent of Meloidogyne javanica on Tobacco

The efficacy of the nematode parasite Paecilomyces lilacinus, alone and in combination with phenamiphos and ethoprop, for controlling the root-knot nematode Meloidogyne javanica on tobacco and the ability of this fungus to colonize in soil under field conditions were evaluated for 2 years in microplots. Combinations and individual treatments of the fungus grown on autoclaved wheat seed, M. javanica eggs (76,000 per plot), and nematicides were applied to specified microplots at the time of transplanting tobacco the first year. Vetch was planted as a winter cover crop, and the fungus and nematicides were applied again the second year to specified plots at transplanting time. The fungus did not control the nematode in either year of these experiments. The average root-gall index (0 = no visible galls and 5 = > 100 galls per root system) ranged from 2.7 to 3.9 the first year and from 4.3 to 5.0 the second in nematode-infested plots treated with nematicides. Plants with M. javanica alone or in combination with P. lilacinus had galling indices of 5.0 both years; the latter produced lower yields than all other treatments during both years of the study. Nevertheless, the average soil population densities of P. lilacinus remained high, ranging from 1.2 to 1.3 x 106 propagules/g soil 1 week after the initial inoculation and from 1.6 to 2.3 x 104 propagules/g soil at harvest the second year. At harvest the second year the density of fungal propagules was greatest at the depth of inoculation, 15 cm, and rapidly decreased below this level.

Multiple discrete encephalitogenic epitopes of the autoantigen myelin basic protein include a determinant for I-E class II-restricted T cells

Immunization with the autoantigen myelin basic protein (MBP) causes experimental allergic encephalomyelitis (EAE). Initial investigations indicated that encephalitogenic murine determinants of MBP were located only within MBP 1-37 and MBP 89-169. Encephalitogenic T cell epitopes within these fragments have been identified. Each epitope is recognized by T cells in association with separate allelic I-A molecules. A hybrid I-E-restricted T cell clone that recognizes intact mouse (self) MBP has been examined. The epitope recognized by this clone includes MBP residues 35-47. When tested in vivo, p35-47 causes EAE. T cell recognition of p35-47 occurs only in association with I-E molecules. These results provide the first clear example that antigen-specific T cells restricted by I-E class II molecules participate in murine autoimmune disease. Furthermore, it is clear that there are multiple (at least three) discrete encephalitogenic T cell epitopes of this autoantigen, each recognized in association with separate allelic class II molecules. These results may be relevant to human autoimmune diseases whose susceptibility is associated with more than one HLA-D molecule.

Characterization of a major encephalitogenic T cell epitope in SJL/J mice with synthetic oligopeptides of myelin basic protein

The C-terminal 89-169 amino acid fragment of myelin basic protein (MBP) causes experimental allergic encephalomyelitis (EAE) in SJL/J mice. In order to identify the encephalitogenic T cell epitope, we have examined the fine specificity of encephalitogenic SJL/J T cell clones with synthetic peptides derived from the C-terminal 89-169 amino acids of MBP. These peptides were examined for their immunogenic and encephalitogenic activity in the SJL/J mouse. The SJL/J-derived, encephalitogenic T cell clone, 4b.14a, was shown to be responsive to rat myelin basic protein synthetic peptides pR89-101 (VHFFKNIVTPRTP) as well as to intact MBP. Its response was effectively blocked by mAb 10-2.16 (anti-I-As) as was the response to intact MBP. Furthermore, pR89-101 was revealed to be highly immunogenic for the (PLSJ)F1 mouse in terms of lymphocyte proliferation, but not for the PL/J mouse, in spite of the fact that there exists a strong bias to H-2u restricted responses in the (PLSJ)F1 mouse at the T cell level. By using pR89-101, T cells of (PLSJ)F1 origin were revealed to recognize the peptide in association with the I-As molecule on (PLSJ)F1 antigen presenting cells (APC). When examined for encephalitogenicity for the SJL/J mouse, pR89-101 was found to be as encephalitogenic as intact rat MBP. These results demonstrated that MBP peptide pR89-101 is a major encephalitogenic determinant for the SJL/J mouse.

Can the accuracy of intraocular lens calculations be improved?

Regression analysis of data from 222 extracapsular cataract extractions was performed to determine if the accuracy of IOL prediction in cataract surgery can be improved. Polynomial and piecewise regression of large, medium, and short eyes were used to calculate new formulas for IOL prediction. The Taylor series representation of the theoretical lens power formula was calculated to determine what combination of the variables for IOL power prediction are reasonable to consider in constructing a polynomial regression model. The formulas calculated from the data in this study were compared with other published methods of IOL calculation. In this study, the difference between the postoperative refraction error and emmetropia was independent of the formula used. The exception was the modified Binkhorst formula, which caused greater error. Inclusion of higher order terms in the regression formula or piecewise regression did not reduce the postoperative refractive error.

Limited heterogeneity of T cell receptors from lymphocytes mediating autoimmune encephalomyelitis allows specific immune intervention

Experimental allergic encephalomyelitis (EAE) is an induced autoimmune disease mediated by CD4+ T lymphocytes. Analysis of T cell receptors of myelin basic protein-specific encephalitogenic T cell clones derived from six different PL/J (H-2u) or (PL/J x SJL) F1 (H-2uxs) mice revealed a limited heterogeneity in primary structure. In vivo, the majority of T lymphocytes recognize the N-terminal MBP-nonapeptide in association with I-Au and utilize the V beta 8 gene element. cDNA-sequencing showed that all T cell receptors from a panel of such T cell clones, grown in vitro, share the same V alpha gene segment. Despite heterogeneity in the D-J regions, the clones unexpectedly display a striking similarity in fine specificity. Based on these results, prevention and reversal of autoimmune disease with V beta 8-specific monoclonal antibodies was achieved.

Predominant expression of a T cell receptor V beta gene subfamily in autoimmune encephalomyelitis

TCR beta chain gene expression of individual T cell clones that share the same MHC class II restriction and similar fine specificity for the encephalitogenic NH2 terminus of the autoantigen myelin basic protein (MBP) has been examined. TCR V beta expression was examined by FACS analysis with mAbs specific for the V beta 8 subfamily of TCR beta chain genes. 14 of 18 (78%) NH2-terminal MBP-specific clones examined express a member of the TCR V beta 8 subfamily. Southern analysis was used to identify which member(s) of the TCR V beta 8 subfamily is expressed by these clones. Each of four clones examined uses V beta 8.2, though two different V beta 8.2-J beta 2 combinations were identified. Our findings indicate that there is restricted TCR V beta usage in the autoimmune T cell response to the dominant encephalitogenic NH2-terminal epitope of the MBP. The use of an mAb to the antigen-specific TCR in the prevention of T cell-mediated autoimmune disease has been investigated. Our results demonstrate that in vivo administration of a TCR V beta 8-specific mAb prevents induction of autoimmune encephalomyelitis.

The attractive forces between polar lipid bilayers

Long-range attractive forces between lipid bilayers are not well described by the Lifshitz theory of Van der Waals forces between macroscopic media. It is shown that when correlations between polar headgroups are taken into account, the predicted forces take a qualitatively different form consistent with the measured data.