Enhanced self-pumped phase conjugation from 16 degrees -cut KNSBN:Cu

With the maximum coupling coefficient and high internal reflection conditions, the self-pumped phase-conjugation reflectivity of copper-doped potassium sodium strontium barium niobate (KNSBN:Cu) is increased with 16 degrees -cut samples. The response time is also shortened. The resolution property of 16 degrees -cut KNSBN:Cu is determined and a distorted image is corrected by using the 16 degrees -cut sample.

Role of endothelium-derived prostaglandins in hypoxia-elicited arteriolar dilation in rat skeletal muscle

The aims of the present study were to determine the response of rat cremaster muscle first-order arterioles to hypoxia and the role of endothelium-derived prostaglandins in the response. Isolated arterioles were cannulated, pressurized to 65 mm Hg, and studied in a no-flow condition in a bath containing Krebs' bicarbonate solution, pH 7.4, equilibrated with 21% O2-5% CO2-74% N2 (PO2, 150 mm Hg) or 95% N2-5% CO2 (PO2, 15 mm Hg [hypoxia]). Responses to hypoxia and vasoactive substances were studied before and after removal of the endothelium or blockade of prostaglandin synthesis by the administration of indomethacin (10(-5) M). Addition to the suffusion solution of arachidonic acid (10(-7) and 10(-6) M), prostaglandin E2 (10(-9) and 10(-8) M), acetylcholine (10(-8) and 10(-6) M), or sodium nitroprusside (10(-8) M) evoked significant arteriolar dilation. When the bath PO2 was reduced from 150 to 15 mm Hg, arteriolar diameters increased by 58.8 +/- 9.3 microns (61%). Removal of the endothelium completely inhibited responses to hypoxia, acetylcholine, and arachidonic acid, whereas responses to sodium nitroprusside and prostaglandin E2 remained unaltered. In arterioles with an intact endothelium, indomethacin completely inhibited the responses to hypoxia and arachidonic acid, whereas responses to acetylcholine and sodium nitroprusside were unaltered. These findings support the conclusion that endothelium-derived prostaglandins mediate the arteriolar dilation to hypoxia in rat skeletal muscle arterioles.

Prediction of recurrence in giant cell bone tumors by DNA cytometry

The most interesting therapeutic aspect of giant cell bone tumors is which patients can be cured without a risk of recurrence by intralesional surgery (curettage). To find out the suitability of some DNA cytometric and morphometric parameters for showing differences between this group of patients (n = 9) and those with recurrence (n = 12), the parameters mean ploidy, 2cDI (mean square deviation of the tumor cell DNA content from the normal 2c value), mean nuclear area and its variability were calculated from cytologic specimens prepared by a cell separation technique from formalin-fixed, paraffin-embedded tissues, measuring the values of 100 stromal cells per case by a TV image analysis system. Further measurements were performed on 19 cases of different diseases of the bone and on an additional 17 cases of giant cell tumors without follow-up. The 2cDI allowed us to distinguish the two groups of patients, with and without recurrence, without overlap; even the lowest value for patients with recurrence was higher than the highest value for cured ones. Mean ploidy analysis resulted in a less convincing discrimination of the patients. Mean nuclear area and its variability failed to predict recurrence. Single-cell DNA cytometry provided a parameter, 2cDI, that was able to predict recurrence in patients with giant cell bone tumors with high sensitivity.

A monoclonal anti-idiotype specific for human polyclonal IgM rheumatoid factor

One of the hallmarks of rheumatoid arthritis (RA) is the production of high titers of rheumatoid factor (RF) antibody directed against the Fc portion of IgG. Anti-Id that recognize the majority of monoclonal RF from patients with B cell dyscrasias are reactive with only 1 to 2% of these polyclonal RF from RA patients. We describe a new monoclonal anti-Id, 4C9, that recognizes a L chain determinant on polyclonal IgM RF from patients with RA but does not recognize a panel of monoclonal RF from patients with B cell malignancies. 4C9 reactivity is found in the serum of 34/43 RF-positive RA patients and in 12/12 RF-positive synovial fluids, but in only 1/14 RF-negative sera from RA patients and 1/22 sera containing monoclonal IgM RF. 4C9 reactivity is highly enriched in purified IgM RF from nine RA patients and represents a variable percentage of total IgM RF up to a maximum of 23%. Furthermore, 4C9 reactivity is enriched in the synovial fluid of three of five RA patients compared with serum, suggesting that 4C9-reactive IgM RF are synthesized within the joint. IgG RF from RA synovial fluids are not 4C9 reactive, indicating either that different genes are used to encode IgM and IgG RF in RA patients, or that IgG RF have somatically mutated away from idiotypic reactivity.

A monoclonal anti-idiotype specific for human polyclonal IgM rheumatoid factor

One of the hallmarks of rheumatoid arthritis (RA) is the production of high titers of rheumatoid factor (RF) antibody directed against the Fc portion of IgG. Anti-Id that recognize the majority of monoclonal RF from patients with B cell dyscrasias are reactive with only 1 to 2% of these polyclonal RF from RA patients. We describe a new monoclonal anti-Id, 4C9, that recognizes a L chain determinant on polyclonal IgM RF from patients with RA but does not recognize a panel of monoclonal RF from patients with B cell malignancies. 4C9 reactivity is found in the serum of 34/43 RF-positive RA patients and in 12/12 RF-positive synovial fluids, but in only 1/14 RF-negative sera from RA patients and 1/22 sera containing monoclonal IgM RF. 4C9 reactivity is highly enriched in purified IgM RF from nine RA patients and represents a variable percentage of total IgM RF up to a maximum of 23%. Furthermore, 4C9 reactivity is enriched in the synovial fluid of three of five RA patients compared with serum, suggesting that 4C9-reactive IgM RF are synthesized within the joint. IgG RF from RA synovial fluids are not 4C9 reactive, indicating either that different genes are used to encode IgM and IgG RF in RA patients, or that IgG RF have somatically mutated away from idiotypic reactivity.

Interaction between oligodendroglia and immune cells: mitogenic effect of an oligodendrocyte precursor cell line on syngeneic T lymphocytes

We analyzed cellular interactions between T lymphocytes and a recently established immortal glial line, L3 that retains several properties of immature oligodendrocytes (Aloisi et al., J Neurosci Res 27:16-24, 1990). L3 oligodendrocytes (L3-OL) cannot be induced to express class II antigens, nor do they specifically present antigen to syngeneic specific T lymphocyte. However, L3-OL strongly enhance the proliferation of freshly activated, interleukin-2(IL-2)-dependent T-line lymphocytes and concanavalin A (ConA)-activated lymphoblasts, irrespective of their antigen specificity or surface phenotype (CD4+ or CD8+). Resting and some activated T cells were susceptible to the mitogenic effect of L3-OL only in the presence of exogenous IL-2, not of other cytokines. The mitogenic effect of L3-OL did not depend on cell viability. It was observed in paraformaldehyde-fixed L3-OL cells and in membrane preparations, but not in culture supernatant. Neither intact L3-OL cells nor membrane preparations had direct IL-2 activity. The conclusion that the mitogenic effect of L3-OL cells is exerted by membrane structures acting as a costimulatory factor(s) of IL-2 is supported by the finding that it is largely blocked by a monoclonal anti-IL-2 receptor antibody. The effect is distinct from membrane-bound IL-1, membrane-bound tumor necrosis factor-alpha (TNF-alpha), IL-3, or IL-6 and cannot be reconstituted by these cytokines.

Structure-activity relationships of (+)-CC-1065 analogues in the inhibition of helicase-catalyzed unwinding of duplex DNA

(+)-CC-1065 is a potent antitumor antibiotic produced by Streptomyces zelensis. Previous studies have shown that the potent cytotoxic and antitumor activities of (+)-CC-1065 are due to the ability of this compound to covalently modify DNA. (+)-CC-1065 reacts with duplex DNA to form a (N3-adenine)-DNA adduct which lies in the minor groove of DNA overlapping with a five base-pair region. As a consequence of covalent modification with (+)-CC-1065, the helix bends into the minor groove and also undergoes winding and stiffening. In the studies described here, we have constructed templates for helicase-catalyzed unwinding of DNA that contain site-directed (+)-CC-1065 and analogue DNA adducts. Using these templates we have shown that (+)-CC-1065 and select synthetic analogues, which have different levels of cytotoxicity, all produce a significant inhibition of unwinding of a 3'-tailed oligomer duplex by helicase II when the displaced strand is covalently modified. However, the extent of helicase II inhibition is much more significant for (+)-CC-1065 and an analogue which also produced DNA winding when the winding effects are transmitted in the opposite direction to the helicase unwinding activity. This observed pattern of inhibition of helicase-catalyzed unwinding of drug-modified templates was the same for a 3'-T-tail, for different duplex region sequences, and with the Escherichia coli rep protein. Unexpectedly, the gel mobility of the displaced drug-modified single strand was dependent on the species of drug attached to the DNA. Last, strand displacement by helicase II coupled to primer extension by E. coli DNA polymerase I showed the same pattern of inhibition when the lagging strand was covalently modified. In addition, the presence of helicase II on single-stranded regions of templates caused the premature termination of primer extension by DNA polymerase. These results are discussed from the perspective that (+)-CC-1065 and its analogues have different effects on DNA structure, and these resulting structural changes in DNA molecules are related to the different in vivo biological consequences caused by these drug molecules.

Synthetic peptides representing sequence 39 to 59 of rat V beta 8 TCR fail to elicit regulatory T cells reactive with V beta 8 TCR on rat encephalitogenic T cells

Subpathogenic doses of syngeneic autoreactive T cells protect experimental animals against associated autoimmune disease. Preferential use of the TCR of encephalitogenic T cells suggests that this molecule serves as the target for immunoregulation in experimental autoimmune encephalomyelitis (EAE). Whether peptides derived from the V beta 8 of the rat TCR elicit regulatory T cells and produce the same vaccinating effect against EAE as do whole T cells remains unknown. Here we show that immunization of Lewis rats with V beta 8(39-59), a peptide representing residues 39 to 59 of the rat V beta 8 TCR, does not induce the production of regulatory T cells reactive to the intact TCR V beta 8 containing this sequence. Moreover, animals that had recovered from both actively induced EAE and transferred EAE did not generate regulatory T cells that recognized the V beta 8(39-59) peptide. Further, transfusion of large doses of peptide-specific T cells did not protect the animals from EAE. Our results suggest that the V beta 8(39-59) peptide may comprise so-called cryptic epitopes, which function as immunogens only when dissociated from large protein complexes.

Immune regulation in self tolerance: functional elimination of a self-reactive, counterregulatory CD8+ T lymphocyte circuit by neonatal transfer of encephalitogenic CD4+ T cells lines

Transfer of encephalitogenic, CD4+ T lymphocyte lines into syngeneic adult Lewis rats not only leads to the development of experimental autoimmune encephalomyelitis (EAE), but, in addition, to the expansion of counterregulatory, CD8+ T lymphocyte clones which are able to lyse specifically the encephalitogenic T cells in vitro and to neutralize their encephalitogenic capacity in vivo. In striking contrast, in neonatal rats, which still lack myelin (autoantigens), injection of the same encephalitogenic lines neither mediates EAE, nor confers protection in later life against the myelin-specific T cells. In fact, this treatment results in the life-long functional elimination of counterregulatory, clonotypic CD8+ T lymphocytes, which cannot even be reinduced by repeated injections of the relevant CD4+ T line. These data seem to point to a self-protective T cell control mechanism which is developed within the immune system prior to, and thus independent of the appearance of the appropriate self antigen.

The antitumor agent CC-1065 inhibits helicase-catalyzed unwinding of duplex DNA

The antitumor drug CC-1065 is thought to exert its effects by covalent bonding to N3 of adenine in DNA and interfering with some aspect of DNA metabolism. Therefore, it is of interest to determine what effect this drug has on enzymes involved in various aspects of DNA metabolism. In this report, we examine the ability of two DNA helicases, the dda protein of phage T4 and helicase II of Escherichia coli, to unwind CC-1065-adducted, tailed, oligonucleotides. It is shown that the presence of the drug on DNA strongly inhibits unwinding catalyzed by the T4 and E. coli proteins. A significant difference between the results obtained with the two helicases is that DNAs containing drug on either the tailed or the completely duplex strands are poor substrates for helicase II but dda protein-mediated unwinding is inhibited only when the drug is on the tailed strand. The drug-modified, helicase-released, strands migrate abnormally through a native gel, suggesting that the drug traps an unusual secondary structure generated in the course of protein-mediated unwinding. A kinetic analysis of the drug-inhibited reactions reveals that the helicases are trapped by the DNA-drug complex. This is evidenced by a decrease in the rate of helicase exchange between drug-bound substrate and drug-free duplex. The implications of these results with respect to the mechanism of action of CC-1065 in vivo are discussed.

Interaction between DNA and alpha/beta-type small, acid-soluble spore proteins: a new class of DNA-binding protein

DNA in spores of Bacillus and Clostridium species is associated with small, acid-soluble proteins (SASP) of the alpha/beta type; the presence of these proteins is a major factor in causing spore resistance to UV light, alpha/beta-type SASP did not bind to single-stranded DNA, single- or double-stranded RNA, or DNA-RNA hybrids in vitro. However, these proteins bound a variety of double-stranded DNAs and conferred protection against DNase cleavage. The binding of alpha/beta-type SASP to DNA saturated at a protein/DNA ratio (wt/wt) of 4:1 to 5:1, which is approximately 1 SASP per 4 bp. alpha/beta-type SASP-DNA interaction did not require divalent cations, was independent of pH between 6 and 8, and, for some SASP-DNA pairs, was relatively insensitive to salt up to 0.3 M. The relative affinity of alpha/beta-type SASP for different DNAs was poly(dG).poly(dC) greater than poly(dG-dC).poly(dG-dC) greater than plasmid pUC19 greater than poly(dA-dT).poly(dA-dT), with poly(dA).poly(dT) giving no detectable binding. This order in alpha/beta-type SASP-DNA affinities parallels the facility with which the DNAs adopt an A-like conformation, the conformation in alpha/beta-type SASP-DNA complexes. An oligo(dG).oligo(dC) of 12 bp was bound by alpha/beta-type SASP. While a 26-bp oligo(dG).oligo(dC) bound more tightly than the 12-mer, there was no significant increase in affinity for alpha/beta-type SASP with further increase in size of oligo(dG).oligo(dC). In contrast, binding of alpha/beta-type SASP to oligo(dA-dT).oligo(dA-dT) was minimal up to at least a 70-mer, and binding to poly(dA-dT).poly(dA-dT) was very cooperative. In addition to blocking DNase digestion, binding of alpha/beta-type SASP to DNA blocked (i) cleavage of the DNA backbone by hydroxyl radicals and orthophenanthroline-Cu2+, (ii) DNA cleavage by restriction enzymes, in particular those with specificity for GC-rich sequences; and (iii) in vitro transcription of some but not all genes. However, methylation of dG residues by dimethyl sulfate was not affected by alpha/beta-type SASP binding.

Endothelium-dependent dilation to L-arginine in isolated rat skeletal muscle arterioles

The vascular actions of L-arginine (L-Arg) were studied in isolated, pressurized first-order rat cremaster muscle arterioles (93 +/- 2.9 microns) bathed in a Krebs bicarbonate-buffered solution, pH 7.4, equilibrated with 21% O2-5% CO2. Arterioles were studied before and after either the administration of NG-nitro-L-arginine (L-NNA, 10(-3) M), an inhibitor of the synthesis of endothelium-derived relaxing factor (EDRF), or the removal of the endothelium. Acetylcholine (ACh, 10(-8) and 10(-6) M), sodium nitroprusside (SNP, 10(-8) M) and phenylephrine (PE, 10(-7) M) evoked dilation and constriction, respectively. L-Arg, (10(-5)-10(-3) M) the precursor of EDRF, evoked dose-dependent arteriolar dilation; whereas D-arginine (D-Arg, 10(-5)-10(-3) M) was without any significant effect. Administration of L-NNA significantly reduced basal diameters and significantly inhibited the arteriolar dilations to both ACh and L-Arg but had no effect on the dilation to SNP. Removal of the arteriolar endothelium with air inhibited dilations to both ACh and L-Arg, had no effect on responses to SNP, and potentiated vasoconstrictor responses to PE. These findings suggest that in skeletal muscle arterioles the dilations to ACh and L-Arg are endothelium dependent and that microvascular endothelium modulates constrictor responses to PE. Thus EDRF may play an important role in the local regulation of arteriolar resistance and blood flow.

Effect of the (+)-CC-1065-(N3-adenine)DNA adduct on in vitro DNA synthesis mediated by Escherichia coli DNA polymerase

(+)-CC-1065 is a potent antitumor antibiotic produced by Streptomyces zelensis. Previous studies have shown that the potent cytotoxic and antitumor activities of (+)-CC-1065 are due to the ability of this compound to covalently modify DNA. (+)-CC-1065 reacts with duplex DNA to form an N3-adenine DNA adduct which lies in the minor groove of the DNA helix overlapping with a 5-base-pair region. As a consequence of covalent modification with (+)-CC-1065, the DNA helix bends into the minor groove and also undergoes winding and stiffening [Lee, C.-S., Sun, D., Kizu, R., & Hurley, L. H. (1991) Chem. Res. Toxicol. 4, 203-213]. In the studies described here, in which we have constructed site-directed DNA adducts on single-stranded DNA templates, we have shown that (+)-CC-1065 and select synthetic analogues, which have different levels of cytotoxicity, all show strong blocks against progression of Klenow fragment, E. coli DNA polymerase, and T4 DNA polymerase. The inhibition of bypass of drug lesions by polymerase could be partially alleviated by increasing the concentration of dNTPs and, to a small extent, by increasing polymerase levels. Klenow fragment binds equally well to a DNA template adjacent to a drug modification site and to unmodified DNA. These results taken together lead us to suspect that it is primarily inhibition of base pairing around the drug modification site and not prevention of polymerase binding that leads to blockage of DNA synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of rat encephalitogenic T cells bearing non-Vβ8 T cell recepotors

In this study, we demonstrate that T cell lines specific for a synthetic peptide representing sequence 87 to 99 of myelin basic protein (MBP) are encephalitogenic in Lewis rats. However, unlike syngeneic T cells specific for MBP residues 68 to 88 which exclusively use V beta 8 in their antigen receptors, these cells do not. None of the 10 T cell lines and T hybridomas specific for MBP (87-99) used V beta 8 in their T cell receptors. Our results document for the first time that rat encephalitogenic T cells do not exclusively use V beta 8 in T cell receptors that rat encephalitogenic T cells specific for MBP (87-99) are heterogeneous and that MBP (87-99) contains at least two epitopes for rat T cells.

Effect of chromosome location of Bacillus subtilis forespore genes on their spo gene dependence and transcription by E sigma F: identification of features of good E sigma F-dependent promoters

Translational lacZ fusions to forespore genes of Bacillus subtilis were not expressed in spoIIAC (sigma F) or spoIIIE mutants when the lacZ fusions were integrated at the loci of the same genes or at the SP beta locus. However, some of these genes, including gerA, gpr, spoIIIG (sigma G), and sspE, were expressed in spoIIIE mutants and spoIIIE spoIIIG double mutants (but not in spoIIAC mutants) when the lacZ fusions were integrated at the amyE locus. When tested, the beta-galactosidase made in these mutants was found only in the forespore, and the 5' ends of the mRNAs produced in these mutants were identical to those in a Spo+ background. Analysis of the in vitro transcription of forespore genes by RNA polymerase containing sigma F (E sigma F) revealed a direct correlation between good in vitro transcription by E sigma F and expression at the amyE locus in spoIIIE mutants. This result suggests that forespore genes are transcribed by E sigma F in spoIIIE and spoIIIE spoIIIG mutants. Comparison of the promoter regions of genes transcribed well and poorly by E sigma F in vivo and in vitro showed that good transcription by E sigma F was correlated with G residues at positions -15 and -16, a purine residue at position -13, and a T residue at position -7 relative to the start site of transcription. The importance of these residues in sigma F recognition was confirmed by analysis of the E sigma F-dependent transcription in vivo and in vitro of mutant ssp genes.

Analysis of T cell receptor beta chains in Lewis rats with experimental allergic encephalomyelitis: conserved complementarity determining region 3

This study explores the usage of T cell antigen receptor (TCR) beta chain elements in Lewis rats with experimentally induced allergic encephalomyelitis (EAE). TCRs from 15 different T cell clones and hybridomas derived from animals immunized with myelin basic protein (MBP), and all having specificity for the 21-mer encephalitogenic fragment MBP 68-88, utilized V beta 8.2. In addition, there was a marked conservation of the first two amino acid residues of the junctional complementarity determining region 3 (CDR3) associated with the V beta 8.2 receptors. 12 of 15 contained an aspartic acid followed by serine regardless of the associated J beta element. At the nucleotide level, this conservation of AspSer residues was accomplished with few or no nongermline-encoded nucleotide (N) additions. A similar pattern of AspSer usage and N region nucleotide additions was observed in a number of V beta 8.2 isolates derived from MBP-immunized lymph nodes. In contrast, V beta 8.2 polymerase chain reaction amplified isolates from Lewis T cells activated with concanavalin A or from lymph nodes of complete Freund's adjuvant-immunized animals showed no AspSer utilization (0/31) in the CDR3, and four to nine N region nucleotide additions. We conclude from this finding that AspSer residues in the CDR3, limited N region nucleotide additions, along with V beta 8.2 sequences, contribute to TCR specificity for MBP 68-88. This raises the possibility that encephalitogenic, disease-causing T cells either represent a population that derives from late fetal life or alternatively, that they are rare cells with this particular TCR phenotype contributed to the T cell pool throughout adulthood and are selected by antigen. In either case, the CDR3 AspSer sequences as well as V beta 8.2 sequences are candidates for the receptor target structures recognized by regulator T cells in recovery from and resistance to active EAE. In this respect, a preliminary analysis of TCR utilization in three T cell clones specific for MBP 68-88 isolated from animals recovered from active EAE indicates that while all three use V beta 8.2, only one contains AspSer in the CDR3.

Enhanced interferon-gamma-induced Ia-antigen expression by glial cells after previous exposure to this cytokine

Encephalitogenic T cells appear capable of destroying class II major histocompatibility complex (MHC) antigen (Ia)-positive glial cells in the brain, thus accounting for the pathologic activity of these lymphocytes in experimental autoimmune encephalomyelitis (EAE). However, glial cells do not generally express Ia molecules, suggesting that regulation of Ia expression figures prominently in autoimmune diseases of the central nervous system. In studies to understand the regulatory mechanisms involved in Ia expression, a glial cell clone generated from the brains of neonatal Lewis rats (F10 clone) readily expressed class II major histocompatibility (Ia) antigens after stimulation by interferon-gamma (IFN-gamma) at doses from 10 to 100 units/ml. Level of the antigen decreased gradually within 5-7 days after cultures were depleted of the cytokine. Reexposure of the cells to the IFN-gamma at 100-fold lower doses induced a stronger Ia response than did the initial exposure. F10 cells also expressed Ia when they were cultured with small numbers of syngeneic T lymphocytes, either proliferating or nonproliferating. Proliferating T cells had direct Ia-inducing activity, whereas nonproliferating T cells had this effect only when they were added to cultures with small amounts of T cell-specific antigen. Moreover, Ia-inducing effects of IFN-gamma on F10 cells were also greatly enhanced when these cells were preexposured to T cells. Our results suggest that initial exposure to IFN-gamma or T cells enhances the Ia responsiveness of glial cells to further stimulation with the cytokine.

Effect of structural variations in cholesteryl-conjugated oligonucleotides on inhibitory activity toward HIV-1

A number of oligonucleotide analogues containing internucleoside phosphorothioate linkages and a covalently attached cholesteryl residue was synthesized and tested for activity against HIV-1 in cultures of Molt3 cells. Structural features important for high antiviral activity are the presence of a cholesteryl moiety, a run of terminal phosphorothioate groups, and the presence of nucleoside residues. An increase in length of the tether between cholesteryl and phosphorus from six to 14 atoms has no significant effect on antiviral activity, and up to one-half of the internucleoside links in a cholesteryl-conjugated phosphorothioate oligomer and one-third of the internucleoside links in a nonconjugated phosphorothioate can be replaced with phosphodiester links without much change in antiviral activity. However, replacement of nucleoside units in the oligomers by a simple analogue (-OCH2CH2CH2O-) yields inactive or very weakly active compounds, even in the presence of a cholesteryl group. Dose-response patterns for assays in which cholesteryl-conjugated oligomers are added to test cells either simultaneously or subsequently to viral infection are similar for homooligomer derivatives and for oligomers containing "antisense" sequences, suggesting a similarity in mode of action for the two classes of oligomers in this system.

CD4-CD8- splenic T cells from Lewis rats recovered from experimental autoimmune encephalomyelitis respond to encephalitogenic T cells that mediate this disorder

We previously demonstrated that encephalitogenic CD4+ T lymphocytes from the long-term cultured line S1, specific for myelin basic protein, induce a CD8+ T cell population in vivo that protects naive Lewis rats against experimental autoimmune encephalomyelitis caused by S1 cells. In order to determine the contribution of individual T cell population in the development of induced resistance, we have analyzed the in vitro proliferative capacity of phenotypically distinct T cell populations isolated from S1-immunized rats. We found that both CD8+ and CD8-CD4- T cells show striking proliferative responses when stimulated with S1 cells, whereas CD4+ T cells show only minimal responses. In addition, a significant proportion of the CD8-CD4- cells, after stimulated by S1 cells, became CD8+ and had a strong cytolytic activity toward S1 cells. These results suggest a contribution of double-negative splenic T cells in the regulatory circuit associated with autoimmune encephalomyelitis.

High-performance self-pumped phase conjugator with a multichannel in KNSBN:Cu crystal

A Cu-doped (0.04 wt. %) (K(0.5)Na(0.5))(0.2)(Sr(0.61) Ba(0.39))(0.9)Nb(2)O(6) crystal produced as much as 68% self-pumped phaseconjugate reflectivity at the laser wavelength lambda = 514.5 nm. We also observed some phenomena that helped us to understand the mechanism for the self-pumped phase-conjugate mirror.

Analysis of transcriptional control of the gerD spore germination gene of Bacillus subtilis 168

The gerD locus of Bacillus subtilis comprises a single gene whose function is essential for the germination of B. subtilis spores in media containing asparagine, glucose, and fructose. The expression of gerD has been characterized by using a chromosomal lacZ fusion to the gerD promoter. The promoter is switched on at the same time as the synthesis of glucose dehydrogenase, 2.5 h after sporulation has been initiated in the developing forespore. The gerD gene is not expressed in spoIIB or spoIIIA, -IIIB, -EIII, -FIII, or -IIIG mutants, but it is expressed in spoIIIC and -IIID and spoIVA mutant backgrounds. The in vivo transcriptional start point of the gene has been mapped by primer extension analysis, and sequences upstream from the start point show considerable homology with the promoter consensus sequences recognized by RNA polymerase containing the forespore-specific sigma factor sigma G (E sigma G). gerD is transcribed in vitro by E sigma G with a similar if not identical start point to that found in vivo, and expression of the gene can be rapidly induced in vegetative cells following the induction of sigma G synthesis. These results indicate that gerD is another member of the sigma G regulon, which includes a number of genes expressed only in the forespore compartment of sporulating cells of B. subtilis.

The causes and complications of late diagnosis of foreign body aspiration in children. Report of 210 cases

Late diagnoses of foreign body aspiration were defined as occurring beyond 3 days between the aspiration of the foreign body, or onset of symptoms, and correct diagnosis. We reviewed a total of 210 children with late diagnosis of foreign body aspiration. The causes creating late diagnosis of foreign body aspiration in children were as follows: (1) parental negligence (106/210, 50%); (2) misdiagnosis by the fellow professionals and pediatricians (39/210, 19%); (3) the normal chest roentgenographic findings (29/210, 14%); (4) lack of typical symptoms and signs (26/210, 12%); (5) mismanagement (8/210, 4%); and (6) a negative bronchoscopic finding (2/210, 1%). The most common complications encountered were obstructive emphysema (77/186, 41%), mediastinal shift (63/186, 34%), pneumonia (43/186, 24%), and atelectasis (33/186, 18%) in 186 patients who underwent a chest roentgenographic examination. The incidence of major complications was 64% (48/75) in the children who were diagnosed within 4 to 7 days; however, the complication rate was 70% (39/56) in those with a delay in diagnosis of 15 to 30 days, and 95% (20/21) in the cases with a delay in diagnosis of over 30 days after aspirating the foreign bodies.

A subset of mouse splenic macrophages can constitutively present alloantigen directly to CD8+ T cells

About a third of mouse splenic macrophage (M phi) progenitors give rise to cloned progeny that constitutively induce the selective proliferation of naive allogeneic CD8+ T cells in a CD4+ helper cell-independent manner--a response that is inhibited by mAb to the MHC class I molecules present on the M phi. Colony-mixing experiments indicated that the failure of most M phi clones to present allo-Ag was not due to their suppression of the ability of CD8+ cells to respond, nor did the nonpresenting clones interfere with the activity of the allo-Ag presenting M phi. The allo-Ag presenting phenotypes were found to be a stable characteristic in a panel of cell lines derived from individual clones of M phi. Analysis of the cell lines revealed that the differential expression of allo-APC activity could not be attributed to the levels of MHC class I molecules; rather, the cell lines and the primary M phi clones differ in their expression of a cell-associated costimulator molecule that likely functions to induce the expression of the IL-2R on and the secretion of IL-2 from the T cells.

A subset of mouse splenic macrophages can constitutively present alloantigen directly to CD8+ T cells

About a third of mouse splenic macrophage (M phi) progenitors give rise to cloned progeny that constitutively induce the selective proliferation of naive allogeneic CD8+ T cells in a CD4+ helper cell-independent manner--a response that is inhibited by mAb to the MHC class I molecules present on the M phi. Colony-mixing experiments indicated that the failure of most M phi clones to present allo-Ag was not due to their suppression of the ability of CD8+ cells to respond, nor did the nonpresenting clones interfere with the activity of the allo-Ag presenting M phi. The allo-Ag presenting phenotypes were found to be a stable characteristic in a panel of cell lines derived from individual clones of M phi. Analysis of the cell lines revealed that the differential expression of allo-APC activity could not be attributed to the levels of MHC class I molecules; rather, the cell lines and the primary M phi clones differ in their expression of a cell-associated costimulator molecule that likely functions to induce the expression of the IL-2R on and the secretion of IL-2 from the T cells.