Laser-induced local heating of multilayers

For a multilayer structure illuminated by a laser beam, absorption of optical energy in the absorptive layers and the diffusion of the resultant heat throughout the structure are studied. Analytical and numerical procedures for this study are described, and, as a specific example, the profiles of temperature distribution during recording on a magnetooptical disk are presented. The technique is also expected to be of value for studies of thermal marking and laser annealing.

Performance limitations of an analog method for solving simultaneous linear equations

The limitations inherent in a recently proposed analog method for solving simultaneous linear equations are examined, and methods for overcoming some of these limitations are discussed. In its original form the method requires that all eigenvalues of the matrix of coefficients lie in a unit circle centered on (1,0) in the complex plane. Proper scaling of the matrix and the data vector extends this region to the entire right half of the complex plane (neglecting the effects of noise). A modification of the algorithm is described that allows the region to be further extended to the entire complex plane. If the product of the gains in the forward and feedback branches is not unity, the solution produced by the algorithm is shown to be in error. Finally, the effects of noise, which is inevitably significant in any analog realization of the algorithm, are examined. Noise is found to produce a limiting mean square error of the solution, thus preventing perfect convergence to the ideal solution vector. A procedure for determination of when to stop the iteration is proposed.

Eigenvector determination by noncoherent optical methods

An iterative method for finding the eigenvectors and eigenvalues of a matrix via incoherent optical matrix-vector multiplication and simple electronic feedback is described.

Statistics of modal noise in fibers: a case of constrained speckle

Modal noise in multimode optical fibers is usually analyzed by using the conventional statistical theory developed for speckle. We show that when little light is lost from the fiber to radiative modes, a constraint of constant total power is introduced that is not present in conventional speckle theory. Experimental results show a marked departure in the behavior of speckle signal-to-noise ratio from the predictions of conventional speckle theory. A suitable modification of this theory is introduced, bringing the theoretical and experimental results into agreement.

Idiotype profile of an immune response. I. Contrasts in idiotypic dominance between primary and secondary responses and between IgM and IgG plaque-forming cells

The primary response of A/J mice to p-azobenzenearsonate-keyhole limpet hemocyanin (ABA-KLH) was investigated. A day-by-day analysis at the plaque- forming cell (PFC) level was performed, with inhibition by anti-cross- reactive idiotype (CRI) serum to determine percentage of CRI(+) PFC. A regular pattern in the dynamics of Id (idiotype) dominance was observed. Just as in the NP-b and NP-a systems (9, 12), the major Id (CRI) is more dominant in primary than in secondary or hyperimmune responses. This trend is more apparent in IgG PFC which are generally 80-95 percent CRI(+) at day 10 in the primary response but only 30-40 percent CRI(+) at day 10 in secondary or hyperimmune responses. A somewhat different pattern is seen with IgM PFC. These may reach a peak of 85 percent CRI(+) in the primary response, but secondary or hyperimmune IgM PFC, which are lower in numbers than IgG PFC, remain high in CRI content at approximately 70 percent. The PFC data on extent of id dominance in secondary or hyperimmune responses is fully compatible with previously reported serological data by others. Analysis of IgG PFC by hapten inhibition indicated that heterogeneity was in the order secondary PFC {greater than} primary PFC {greater than} hybridoma AK-2.2 PFC with H(75)/H(25) values of 22.9, 6.2, and 2.7, respectively; where H(75) and H(25) are the hapten concentrations required to give 75 percent and 25 percent of inhibition of PFC, respectively. Hapten inhibition data also suggested that secondary IgG PFC were 10 times higher in median binding avidity for ABA-L-tyrosine than primary IgG PFC. The kinetic analysis strongly indicated that CRI(+) IgM PFC were preferentially switched to IgG PFC in the primary response. In both studies, the CRI content of the earliest-appearing IgG PFC was significantly higher than that of IgM PFC on that day. For example, in one case IgM PFC were 60 percent CRI + on day 6 whereas IgG PFC were 100 percent CRI(+). The high Id dominance and selective isotype switching may have either a B or a T cell basis.

Antigen structural requirements for immunoglobulin isotype switching in mice

L-Tyrosine-p-azobenzene-p-arsonate (RAT) is immunogenic and serves as a carrier for anti-hapten antibody responses in guinea pigs, rats, and mice. However, the murine anti-N-2,4-dinitrophenyl (DNP) plaque-forming cell (PFC) response to the bifunctional antigen 2,4-dinitrophenyl-6-amino-caproyl-L- tyrosine-p-azobenzene-p-arsonate (DNP-SAC-RAT; or BI-1) is extremely weak (2,000-4,000 PFC/spleen) and exclusively IgM in both primary and secondary responses. The 6-amino-caproyl group serves as a spacer in this antigen between the DNP haptenic and RAT carrier epitopes. In view of recent evidence indicating that different T helper cells synergize for optimal antibody responses, a trifunctional antigen, N-2,4- dinitrophenyl-6-amino-caproyl-L-tyrosine-p-azobenze-p-arsonate-(proline)9-L- tyrosine-p-azobenzene-p-arsonate (DNP-SAC-RAT-PRO(9)-RAT; or TRI), was prepared to investigate the effect of adding a second RAT epitope to BI-1. The nonaproline spacer between the two RAT epitopes in TRI is assumed to be a rigid rod of approximately 28 A. TRI induced about twice as many PFC as BI-1 in primary responses of A/J mice, and induced both IgM and IgG PFC in secondary responses. Furthermore, TRI induced IgG PFC responses in mice primed with p-azobenzene-p-arsonate-keyhole limpet hemocyanin, BI-1, or RAT, whereas boosting with BI-1 failed to induce IgG PFC, even in mice primed with TRI. These findings indicate that the minimum antigen structural requirements for inducing IgG PFC in mice are two carrier epitopes and one haptenic epitope. In addition, priming with a mono-epitope carrier (RAT) is sufficient preparation for IgG responses to a trifunctional immunogen. Because TRI differs from BI-1 by the (proline)(9) spacer as well as the additional RAT epitope, two other compounds, N-2,4-dinitrophenyl-6-amino- caproyl-(proline)(9)-L-tyrosine-p-azobenzene-p-arsonate (DNP-SAC-PRO(9)-RAT; or BI-2) and N-2,4-dinitrophenyl-6-amino-caproyl-(proline)(9)-L-tyrosine-p- azobenzene-arsonate (DNP-SAC-RAT-PRO(10); or BI-3), were prepared to evaluate the possible role of the spacer in the observed responses. BI-2, but not BI-3, induced IgG as well as IgM PFC in TRI-primed mice. However, BI-2 failed to induce IgG responses in RAT-primed mice, indicating that TRI and BI-2 were not equivalent immunogens. Because anti-prolyl antibodies had been found in guinea pigs immunized with N-2,4-dinitrophenyl-(proline)10-L-tyrosine-p- azobenzene-p-arsonate (DNP-PRO(10)-RAT), it seemed possible that priming with TRI might induce anti-prolyl antibodies, which, in turn, could cross-link BI-2 molecules into aggregates containing at least two carrier epitopes. To help resolve this question, mice were immunized with acetyl-(proline)10-L- tyrosine-p-azobenzene-p-arsonate and boosted with BI-2. IgG PFC responses were detected, suggesting that anti-prolyl antibodies were indeed responsible, because priming with RAT and boosting with BI-2 did not induce IgG formation. Accordingly, the observations that IgG responses in RAT-primed mice were induced only by TRI and not by any of the bifunctional antigens indicate that two carrier epitopes per antigen molecule are indeed required for IgG induction. They also provide indirect evidence for synergistic help in the switching of immunoglobulin isotypes.

The role of immunoglobulin receptors and T cell mediators in B lymphocyte activation. I. B cell activation by anti-immunoglobulin and anti-idiotype reagents

The possibility that the failure of anti-mouse immunoglobulin (Ig) antibody to induce antibody synthesis by B cells might be due to reversible receptor blockade was investigated. Murine spleen cells were cultured for 3 days in the presence of minute quantities of intact of (Fab') fragments of rabbit anti-mouse Ig antibody. Thereafter, the cells were washed and either trypsin treated or not before reculturing for 18 hr. Only cells that had been trypsinized after culturing with either intact or fragments of anti-Ig gave a vigorous polyclonal antibody response. This response was extremely T dependent, since T cells or culture supernatants from Con A-activated T cells were required for the B cell response. Moreover, anti-delta was much more effective than anti-mu in inducing antibody synthesis. Finally, the use of three different anti-idiotypic antisera rather than anti-Ig reagents selectively activated the specific idiotype in each instance. The findings demonstrate that anti-Ig reagents can potentiate the response of B cells to signals delivered by T cells.

The role of immunoglobulin receptors and T cell mediators in B lymphocyte activation. I. B cell activation by anti-immunoglobulin and anti-idiotype reagents

The possibility that the failure of anti-mouse immunoglobulin (Ig) antibody to induce antibody synthesis by B cells might be due to reversible receptor blockade was investigated. Murine spleen cells were cultured for 3 days in the presence of minute quantities of intact of (Fab') fragments of rabbit anti-mouse Ig antibody. Thereafter, the cells were washed and either trypsin treated or not before reculturing for 18 hr. Only cells that had been trypsinized after culturing with either intact or fragments of anti-Ig gave a vigorous polyclonal antibody response. This response was extremely T dependent, since T cells or culture supernatants from Con A-activated T cells were required for the B cell response. Moreover, anti-delta was much more effective than anti-mu in inducing antibody synthesis. Finally, the use of three different anti-idiotypic antisera rather than anti-Ig reagents selectively activated the specific idiotype in each instance. The findings demonstrate that anti-Ig reagents can potentiate the response of B cells to signals delivered by T cells.

A hemolytic plaque assay for activated murine T cells

In an earlier report, it was shown that murine spleen cells cultured with concanavalin A (Con A) released into the culture supernatants helper and suppressor substances for antibody production. The present communication describes the production of rabbit antisera against culture supernates from Con A-activated spleen cells and their use in a plaque assay for mitogen-activated T cells. The plaque assay, utilizing SRBC to which Staphylococcal protein A had been coupled, the developing anti-supernatant antiserum and guinea pig complement, readily detected secreting T cells. The T-cell nature of the plaque-forming cells (PFC) was established principally by the following: (a) the majority of lymphocytes in the centers of plaques were Thy-1-positive by fluroescence; (b) spleen cells depleted of B cells by incubation in plastic dishes coated with rabbit anti-mouse Ig antibody gave greatly enriched PFC responses; (c) anti-Thy-1 and anti-Lyt-2.2 treatment of spleen cells almost completely depleted PFC; (d) T-cell mitogens (Con A and phytohemagglutinin) but not B-cell mitogens (lipopolysaccharides) induced PFC responses; (e) T cells maintained in culture for 10 d with Con A and T-cell growth factor yielded PFC. Kinetic and dose response studies showed that high doses of mitogen induced rapidly appearing T-PFC and the responses peaked at day 1--2 of culture. Lower doses of mitogen-induced PFC required longer periods of incubation for detection, indicating that cell activation and secretion may be different dose-dependent activities of mitogens. Another noteworthy finding was that the antiserum reacted with surface antigens of T-PFC, indicating that secreted products are expressed on the membranes of T cells, offering the possibility of isolating populations of cells with specific secretory potential. Although the precise nature of the T-cell products detected by the antiserum used in this assay are unresolved, 10% of the target-cell-adherent population from spleen cells of BALB/c mice sensitized to L929 cells formed plaques. This suggests that the antiserum has significant activity against the products of cytotoxic T cells, a finding which accords with the activity of anti-Lyt-2.2 serum against mitogen-induced T-PFC. The method clearly offers new possibilities for the analysis of T cells and their products and should provide an important approach to the clonal analysis of lymphokine production.

Macrophage-T cell interaction mediated by immunogenic and non-immunogenic forms of a monofunctional antigen

As an approach to the elucidation of the essential steps in the immune pathway, the uptake and retention of immunogenic and non-immunogenic analogs of a monofunctional antigen by guinea pig macrophages and the efficiency of macrophages pulsed with the compounds to present antigen to sensitized T lymphocytes were compared. L-Tyrosine-azobenzene-p-arsonate (RAT) and its non-immunogenic analog, 4-hydroxyphenyl-n-propane-3-azobenzene-p-arsonate (RAN), react similarly with antiarsonate antibody, but RAN, unlike RAT, is unable to induce cellular immunity in guinea pigs. The uptake and retention patterns of the two compounds by macrophages differed in that, at a given time, more RAN than RAT was retained and detectable on cell surfaces by anti-arsonate antibody. Equivalent numbers of T lymphocytes from guinea pigs sensitized to RAT formed antigen-dependent clusters with macrophages pulsed with either RAT or RAN after 24 hr in culture, but not with macrophages pulsed with an azobenzenoid compound of unrelated specificity. On the other hand, T lymphocytes from guinea pigs immunized with RAN showed no significant capacity to bind to macrophages which had been pulsed with any of the compounds. The number of lymphocytes from RAT-sensitized animals which bound to RAT-pulsed macrophages remained relatively stable over a 48 hr period, whereas clusters of the same lymphocytes with RAN-pulsed macrophages dissocitated to background levels within that time. Early cluster formation mediated by RAN, as well as its ability to induce transient specific T cell unresponsiveness to RAT in vivo, indicate that T cells are capable of recognizing (binding) the non-immunogen. However, such early, and perhaps weak, interaction with RAN-pulsed macrophages did not induce DNA synthesis by T cells. Anti-Ia serum completely blocked cluster formation mediated by either RAT or RAN. Thus, the only significant distinction disclosed by these studies between the immunogenic and non-immunogenic compounds was the stability of macrophage-T cell interaction as determined by the persistence of antigen mediated cell clusters in culture, suggesting that this may be a factor in immunogenic discrimination.

Rosette formation between murine lymphocytes and erythrocytes. A new locus in the H-2 region

More than 5% of murine splenic lymphocytes form rosettes with syngeneic erythrocytes. This property was maximally expressed when the lymphocytes were cultured for 24 h before rosetting. About 70% of the rosetting lymphocytes were B cells and 30% were T cells on the basis of surface immunoglobulin and the Thy-1-antigen. Capping surface immunoglobulin had no effect on the capacity of lymphocytes to form rosettes, indicating that the receptor in question was not immunoglobulin. The capacity of lymphocytes to form rosettes with erythrocytes from other strains of mice was H-2 restricted. Extensive pairings of congenic and recombinant strains as donors of lymphocytes and erythrocytes showed that none of the known loci within the H-2 region-controlled rosetting. The involvement of regions on chromosome 17, telomeric or centromeric to H-2, was also excluded. The data were only compatible with the conclusion that this form of self-recognition is associated with a new locus (or loci) mapping between H-2G and H-2D.

Optical computation using residue arithmetic

Using residue arithmetic it is possible to perform additions, subtractions, multiplications, and polynomial evaluation without the necessity for carry operations. Calculations can, therefore, be performed in a fully parallel manner. Several different optical methods for performing residue arithmetic operations are described. A possible combination of such methods to form a matrix vector multiplier is considered. The potential advantages of optics in performing these kinds of operations are discussed.

Thymic involvement in control of bone marrow growth. Use of T-cell-depleted hybrid mice

Because of mounting evidence of involvement of thymus-derived cells in blood formation we have studied the growth of transplanted bone marrow in mice extensively depleted of T-lymphocytes (TCD). Poor growth of parental marrow was found not to be appreciably altered in TCD hybrid recipients. However, parental thymic lymphocytes even in massive doses were not able to augment hemopoiesis in TCD hosts, in contrast to findings from sham-thymectomized or age control mice. This indication that a third (host) cell takes part in the thymocyte-marrow stem cell interaction was reinforced by the finding that isogenic (hybrid) thymocytes administered to TCD mice 5 weeks before the final irradiation restored their ability to support thymocyte-induced augmentation of parental marrow growth. Data were obtained from theta-poor sham-thymectomized irradiated controls which are interpreted as evidence for a suppressor T cell. Thymocytes administered with marrow produced a shift toward granulopoiesis in TCD mice as well as in controls. From this finding we infer that although thymus-derived cells are intimately involved in regulation of myelopoiesis, the effect of administered thymic lymphocytes on the differentiative pathway does not depend on host T cells.

Purification of functional, determinant-specific, idiotype-bearing murine T cells

Strain A/J mice immunized with azobenzenearsonate (ABA)-mouse IgG conjugates develop suppression for anti-trinitrophenyl(TNP) responses to doubly conjugated (ABA,TNP) proteins. This suppression is specific for the ABA epitope and is mediated by T cells in cell transfer experiments. ABA-binding T cells from suppressed animals were purified by a two-stage procedure in which B cells were removed from spleen cell populations by adherence to plastic surfaces coated with anti-mouse Ig antibody, followed by binding the nonadherent population (more 95 percent Thy-1-positive) to surfaces coated with ABA-protein conjugates. Approximately 90 percent of the cells recovered by temperature-dependent elution from the ABA plates (similar to 2 percent of the spleen cells) bound antigen immediately afterward, and up to 50 percent of the cells bound anti-cross-reactive idiotype antibody. On the other hand, the nonadherent T-cell population was completely negative in the antigen- binding and idiotype assays. Another distinguishing feature of the two T-cell populations was that 78 percent of the adherent cells, but only 2 percent of the nonadherent cells, were Ia positive, although the specific I-region marker(s) expressed on the cells was not identified. The biological function of the antigen-binding T cells was investigated using a standard cell transfer protocol. Suppressor cells were enriched in the adherent population by a factor of at least 25, establishing that functional, epitope-specific, idiotype-bearing T cells can be significantly purified by this procedure. Note Added in Proof. We have recently isolated two types of ABA-binding molecules biosynthetically labeled with (35)S-methionine from NP-40 lysates of purified antigen-specific T cells. The molecules were purified by adsorption onto an ABA-Sepharose immunoadsorbent followed by elution with 9 M urea. Autoradiograms of SDS-PAGE of the eluates revealed components with tool wt of approximately 60,000 and 33,000 dahons. These molecules were not present in eluates from a bovine IgG-Sepharose control immunoadsorbent and thus represent specific ABA-binding products synthesized by T cells.

Spatial requirements between haptenic and carrier determinants for T-dependent antibody responses

To gauge the proximity between cooperating T and B cells required for effective triggering of antibody production, guinea pigs were immunized with bifunctional antigens in which the haptenic and carrier determinants were separated by rigid spacers of varied dimension. These took the form 2,4-dinitrophenol-(proline)n-L-tyrosine-p-azobenzenearsonate, where n varied from 1 to 40 proline residues. Animals immunized with n = 10 and n = 22 compounds made strong anti-DNP antibody responses, whereas animals immunized with bifunctional compounds containing longer spacers did not make antibody detectable by precipitation. It can be calculated on the basis of very strong physicochemical evidence for the rigidity and axial translation of poly-L-proline chains in solution that the cut-off point for effective interaction between T and B cells lies between 69 and 97 A U.

Ability of thymic lymphocytes to alter CFU kinetics in radiation chimeras

It is known that the poor colony-forming ability of B6 bone marrow transplanted into B6D2F1 hybrids can be improved if B6 lymphocytes are given in addition. It was recently reported that the augmenting lymphocytes decrease the doubling time of differentiating hemopoietic cells. To determine whether thymus cells alter the self-renewal of CFUs in this parent leads to F1 combination, retransplantation and 3H-thymidine 'suicide' were employed as methods to determine the cell-division rate. We have observed that in the presence of thymocytes, parental bone marrow cells are seeded more efficiently in the spleen, and the lag phase of the CFUs growth curve is shortened. However, thymic lymphocytes do not increase the slope of the exponential growth phase of CFUs.