Identification of allergic bronchopulmonary aspergillosis in cystic fibrosis patients by recombinant Aspergillus fumigatus I/a-specific serology

Before specific therapy, such as oral corticosteroids, can be commenced it is essential to distinguish full-blown allergic bronchopulmonary aspergillosis (ABPA) from allergy to A. fumigatus in patients with cystic fibrosis (CF). For this purpose we have evaluated the diagnostic value of recombinant A. fumigatus allergen I/a (rAsp f I/a)-specific serology in 55 patients with CF. Based on clinical presentation and laboratory data, 10 CF patients had ABPA, 27 had Aspergillus allergy, and 18 were not allergic to A. fumigatus (CF control group). The serologic assays revealed a 10-fold increase in rAsp fI/a-specific IgE, a 5-fold increase in rAsp fI/a-specific IgG1, and a 4-fold increase in rAsp fI/a-specific IgG4 antibodies in ABPA patients compared with the Aspergillus allergy and CF control groups. Sera from 11 CF patients were analyzed without knowledge of their clinical state or diagnosis of ABPA. All ABPA patients (4 of 11) were accurately identified. We conclude that rAsp fI/a-specific serology is a highly sensitive and specific test that can be used to identify ABPA reliably in CF patients.

Black-white differences in response to antihypertensive medication

There appear to be differences in degree and rate of response of black and white subjects to various antihypertensive medications. Diuretics and calcium channel blockers are more effective on average in older black patients than beta blockers or ACE inhibitors. White patients, especially younger individuals, appear to respond somewhat better to beta blockers and ACE inhibitors than to diuretics or calcium channel blockers. When any medications, such as beta blockers, ACE inhibitors, or calcium channel blockers, are combined with small doses of diuretics, the black-white difference in response disappears; black and white patients appear to respond equally well to combination therapy.

Scaling of the antiresonant Fabry-Perot saturable absorber design toward a thin saturable absorber

We demonstrate and discuss the scaling of the antiresonant Fabry-Perot saturable absorber toward a novel antiref lection-coated thin saturable absorber. With a Ti:sapphire laser we obtained self-starting Kerr-lens mode-locked pulses as short as 19 fs. With the higher modulation depth of the thin saturable absorber we obtained soliton mode-locked self-starting 34-fs pulses over the full cavity stability regime with a significantly shorter mode-locking buildup time. The pulse duration was limited only by the semiconductor Bragg mirror.

B7.2 provides co-stimulatory functions in vivo in response to staphylococcal enterotoxin B

Excessive T cell activation induced by bacterial superantigens plays an important role in the pathology associated with Gram-positive bacteremia. To gain insight into the early phases of T cell activation by bacterial enterotoxins in vivo, we investigated the ability of antibodies to well-defined co-stimulatory molecules to inhibit T cell activation and the subsequent toxic shock syndrome induced in BALB/c mice following the injection of staphylococcal enterotoxin B (SEB). We demonstrate here that a single dose of anti-B7.2 antibodies, but not anti-B7.1 antibodies, significantly inhibits T cell activation, as judged by lower systemic IL-2 release, blastogenesis and IL-2 receptor expression, and reduces the lethal effect of SEB in D-galactosamine-sensitized mice. These results demonstrate that co-stimulation through the B7.2 molecule plays an important role in the activation of T cells in response to SEB in vivo and suggest alternative therapies for septic shock caused by bacterial enterotoxins based on blocking antibodies to co-stimulatory molecules.

Activation of murine T cells by bacterial superantigens requires B7-mediated costimulation

Staphylococcus enterotoxins bind class II MHC molecules on antigen-presenting cells (APC) and stimulate T cells expressing appropriate V beta gene products. Although the role of non-TcR-associated costimulatory receptors during antigen-specific T cell stimulation has been clearly established, the involvement of costimulatory activity in T cell activation by superantigens (SAgs) has been the matter of controversy. The aim of this study was to evaluate the role of the costimulatory-receptor ligand molecules CD28/B7 on bacterial SAg-mediated activation of naive murine T cells. We demonstrate in this report that a combination of monoclonal antibodies to murine B7.1 and B7.2 molecules inhibits the in vitro response of naive T cells to SAgs SEA, SEB, and TSST-1. The inhibition of T cell responses required simultaneous blocking of B7.1 and B7.2, suggesting that either B7.1 or B7.2 is sufficient to provide costimulatory signals to naive T cells in response to bacterial exotoxins. Inhibition of T cell activation by antibodies to B7-related molecules can be overcome by antibodies to CD28, a finding in agreement with the hypothesis that CD28-mediated signals participate in T cell activation by bacterial SAgs. These observations suggest that, as demonstrated for conventional antigen, T cell activation by SAgs requires the coordinated participation of TcR- and CD28-derived signals.

Developmental expression of the prion protein gene in glial cells

Replication of prions is dependent on the presence of the host protein PrPc. During the course of disease, PrPc is converted into an abnormal isoform, PrPSc, which accumulates in the brain. Attempts to identify the cell type(s) in which prion replication and PrP conversion occur have reached conflicting results. Although PrP mRNA is present in high amounts in neurons throughout the life of the animal, PrPSc initially accumulates in astrocytes and possibly other glial cells and, later in the course of the disease, spreads diffusely in the tissue, often in white matter. We report here that PrP mRNA is expressed not only in neurons but also in astrocytes and oligodendrocytes throughout the brain of postnatal hamsters and rats. The level of glial Prp mRNA expression in neonatal animals was comparable to that of neurons and increased two-fold during postnatal development. A substantial portion of brain PrP mRNA is therefore contributed by glial cells. Our results provide an explanation for the accumulation of PrPSc in white matter tissue and in the cytoplasm of glial cells and argue for a direct involvement of glia in prion propagation.

Co-stimulation lowers the threshold for activation of naive T cells by bacterial superantigens

Staphylococcus enterotoxins bind class II MHC molecules on antigen presenting cells (APC) and stimulate T cells expressing appropriate V beta gene products. Although the role of non-TCR associated co-stimulatory receptors during antigen-specific T cell stimulation has been clearly established, the involvement of co-stimulatory activity in T cell activation by superantigens has been the matter of controversy. In this report, we examine the role of co-stimulation provided by selected APC populations in the response to bacterial exotoxins (staphylococcal enterotoxin A, staphylococcal enterotoxin B and toxic shock syndrome type 1). We demonstrate that the APC population able to activate naive T cells to IL-2 production is heterogeneous, comprising both adherent (presumably dendritic) and non-adherent (mostly B lymphocytes) cells. By stimulating naive T cells in the presence of graded doses of superantigens, we have observed that half-maximal IL-2 production was achieved at lower doses of superantigens in the presence of dendritic cells. Similarly, addition of antibodies to CD28 or B7.1-transfected cell lines increased the sensitivity of naive T cells to lower doses of superantigens. These observations indicate therefore that superantigens can be presented to naive T cells by APC displaying distinct levels of co-stimulatory activity, although with different efficacy. Thus, naive T cells are sensitive to CD28-mediated co-stimulation during superantigen-mediated responses but IL-2 production can be induced by high doses of superantigens in the presence of APC expressing weak co-stimulatory activity. These observations are compatible with the hypothesis that CD28-mediated signals participate in T cell activation by lowering T cell sensitivity to TCR ligands.

Iodine distribution in a porcine eye model following iontophoresis

Iodine distribution was studied in isolated porcine eyes after iontophoresis using 131I-labelled solutions and chemical methods. After a 15-min treatment with a therapeutically used iodine brine, the iodine content in the ocular tissues showed the following rank order: cornea > retina > vitreous body > anterior chamber fluid > lens. Replacement of the brine by 0.15 M NaI increased the uptake values in a different way, but the same rank order was maintained. The increase was highest in the cornea (5.6-fold) and only about 2-fold in the lens, nevertheless approaching now the level of 10(-4) M, a concentration which was regarded as being optimal for the antioxidant effect of I-. Among the other eye components, the relatively high iodine enrichment of the retina was remarkable. The data are discussed with respect to a possible protective, antioxidative and OH-scavenging efficacy of I- and to previous results in the literature concerning iodine uptake in ocular tissues.

Heart rate variability as a prognostic tool in cardiology. A contribution to the problem from a theoretical point of view

BACKGROUND

Recent clinical studies have proposed standard deviation of heart rate as a diagnostic tool for the outcome of cardiac infarction. Mathematical analysis of heart rate variability shows that heart rate is influenced by different frequency components derived from different parts of the autonomous nervous system. In the experimental part of this study, we investigated the possibility of calculating a variable describing the parasympathetic branch of the autonomous nervous system exclusively.

METHODS AND RESULTS

In 60 healthy volunteers, heart rate was measured to 1 millisecond during two different conditions: 5 minutes of rest, and 5 minutes of intermittent handgrip dynamometry; the latter is known to increase sympathetic arousal selectively. Heart rate was found to be lower at rest (65.9 +/- 9.7 beats per minute) than during dynamometry (72.8 +/- 10.4 beats per minute, P < .001). Respiratory sinus arrhythmia (RSA) calculated from the mean absolute differences between successive heart beats showed no significant change (3.01 +/- 1.62 beats per minute at rest versus 2.97 +/- 1.30 beats per minute during dynamometry). In contrast, standard deviation increased from 5.19 +/- 1.98 to 9.22 +/- 3.56 beats per minute (P < .001).

CONCLUSIONS

It can be concluded from these data as well as from other plots presented in this article that RSA is a measure of the parasympathetic vagal tone, whereas standard deviation is increased by both sympathetic and parasympathetic arousal. Clinical evidence and data from physiological experiments are presented to show that a selective measure of vagal tone like RSA may offer advantages over standard deviation as a prognostic tool in cardiology.

Blood serum transferrin concentration in cattle in various physiological states, in veal calves fed different amounts of iron, and in cattle affected by infectious and non-infectious diseases

Transferrin (Tf) concentrations were determined in cattle in various physiological states, in energy-deficient (ketotic) cows, in situations of several acute and chronic infections, after endotoxin administration and in animals with bovine leucocyte adhesion deficiency (BLAD). Tf concentrations varied between 1.5 and 8.5 g/l and in healthy animals were in the range of 2.0 and 6.6 g/l. Tf concentrations in adult animals were smaller than in young animals and increased in veal calves with iron deficiency above 8 g/l, resulting in a negative correlation between Hb and Tf. In veal calves total iron binding capacity (TIBC) and Tf concentration were rather closely correlated (r = 0.63). Chronic infectious diseases (such as paratuberculosis) were characterized by relatively low Tf levels (below 2 g/l), while during acute infections, after endotoxin-administration and during ketosis Tf concentrations were not changed.

In vivo immunosuppression induced by a weakly mitogenic antibody to mouse CD3: evidence that induction of long-lasting in vivo unresponsiveness requires TcR signaling

The use of anti-CD3 monoclonal antibodies (mAb) to treat allograft rejection has been complicated by the morbidity observed during the first days of treatment, secondary to T cell activation and cytokine release. Available evidence in a mouse model indicates that F(ab')2 fragments of an anti-CD3 mAb are not mitogenic in vitro and can be injected in vivo without apparent toxicity. However, their immunosuppressive capacity is dramatically reduced, suggesting that long-term immunosuppression mediated by anti-CD3 antibodies in vivo may be associated to their mitogenic capacity. This paper demonstrates that a poorly mitogenic anti-CD3 mAb is able to induce potent immunosuppression in vivo with reduced morbidity. This finding suggests that immunosuppression in vivo by anti-CD3 mAbs is not directly related to their activation properties but nevertheless requires signaling capacities. Therefore, immunosuppression in vivo may be best achieved by using antibodies able to deliver an incomplete activation signal to T cells (thus avoiding systemic cytokine release), possibly leading to anergy. The implications of this study for the development of immunosuppressive antibodies are discussed.

Immunoglobulin isotype regulation by antigen-presenting cells in vivo

The isotype and magnitude of the B cell response clearly depends on the in vivo activation of T helper (Th) cells which secrete different lymphokines. Since Th are activated by the presentation of the antigen on specialized cells, we wished to test whether the nature of the antigen-presenting cells (APC) influences the isotypic profile of the humoral response. Data are presented showing that antigen-pulsed dendritic cells (DC) and peritoneal macrophages induce the synthesis of specific antibodies when injected in syngeneic animals. By contrast, a single injection of antigen-pulsed resting B cells does not prime the mice in vivo. Moreover, the injection of antigen-pulsed DC induces the synthesis of specific IgG2a and IgG1 antibodies, whereas peritoneal macrophages favor the production of IgG1 and IgE antibodies specific for the antigen. These data show that the isotype and the amplitude of the B cell response can be regulated by the nature of the APC, and indirectly suggest that Th cell differentiation is controlled at the level of antigen presentation.

Crystal structures of Escherichia coli aspartate aminotransferase in two conformations. Comparison of an unliganded open and two liganded closed forms

Three crystal structures of wild type E. coli aspartate aminotransferase (E.C.2.6.1.1) in space group P2(1) have been determined at resolution limits between 2.6 and 2.35 A. The unliganded enzyme and its complexes with the substrate analogues maleate and 2-methylaspartate resulted in different conformations. The unit cell parameters of the unliganded and the inhibited enzyme are a = 87.2, b = 79.9, c = 89.8 A and beta = 119.1 degrees, and a = 85.4, b = 79.8, c = 89.5 A and beta = 118.6 degrees, respectively. The crystallographic symmetry is pseudo-C222(1). The liganded enzyme structures were solved by difference Fourier techniques from that of a Val39-->Leu mutant partially refined to an R-factor of 0.22 at 2.85 A. They have a "closed" conformation like the chicken mAATase:maleate complex. The models were refined to R-factors of 0.19 (maleate complex) and 0.18 (2-methylaspartate complex) by molecular dynamics and restrained least squares methods. The unliganded crystal form was solved by molecular replacement and refined to an R-factor of 0.19 at 2.5 A resolution. The structure is in a "half-open" conformation, with the small domain rotated about 6 degrees from the closed conformation. The cofactor pyridoxal phosphate has a more relaxed conformation than in mAATase. Both maleate and 2-methylaspartate are hydrogen-bonded to the active site as in mAATase. The C alpha-CH3 bond of 2-methylaspartate is oriented at right angles to the cofactor pyridine ring, the most productive orientation for alpha-deprotonation of the substrate L-aspartate. Comparisons with earlier determined eAATase structures in space group C222(1) revealed differences that can probably be attributed to the somewhat lower resolution of the orthorhombic structures and/or mutations in the eAATases used in those studies. The present P2(1) structures confirm the justification of extrapolating properties of active site point mutants to the vertebrate isozymes. They will serve as reference in the interpretation of the properties of further site-directed mutants in continued studies of structure-function relationships of this enzyme.

Role of T-cell subsets in the bispecific antibody (anti-idiotype x anti-CD3) treatment of the BCL1 lymphoma

We reported previously on the successful use of bispecific antibodies in two well characterized B-cell lymphoma models. These bispecific antibodies were hybrid-hybridoma antibodies with dual specificity for the TcR/CD3 complex and for the tumor-specific idiotype of the surface IgM expressed by the lymphoma cells. Class-matched control antibodies, either monovalent for CD3, monovalent for idiotype, or bivalent for these surface markers, were always used in parallel with the bispecific antibodies. We extended our studies to determine the relative contribution of antibody-dependent cellular cytotoxicity and a T-cell-mediated therapeutic effect in the BCL1 lymphoma model. In tumor-bearing mice depleted of CD4+, CD8+ or both T-cell subsets and treated with bispecific antibodies, we could show that both T-cell populations contribute to the therapeutic outcome and have an additive role. In vitro studies demonstrate that bridging BCL1 tumor cells to T-cells by bispecific antibodies induces T-cell activation and secretion of tumor growth inhibiting lymphokines by both CD4+ and CD8+ T-cell populations. Particularly gamma-interferon seems to be the major tumor-inhibiting substance for BCL1 tumor cells. However, in vivo experiments using anti-cytokine antibodies showed that both gamma-interferon and tumor necrosis factor alpha have an effect on the tumor growth. The former acts directly by inhibiting tumor growth, the latter via an indirect mechanism, possibly by activating macrophages. In conclusion, our results show that induction of targeted cytolytic activity by the direct CD3/TcR cross-linking and development of targeted cytotoxic activity, mediated by gamma-interferon, by both T-cell subsets, contribute to the therapeutic success of bispecific antibody therapy.

Iron status, erythropoiesis, meat colour, health status and growth performance of veal calves held on and fed straw

Two experiments were designed to study the iron (Fe) status in veal calves (62 intact males) fed and held on straw. In experiment 1, two groups were fed 20 mg Fe/kg milk replacer (MR) and held unattached on rye or barley straw litter. In experiment 2, groups were fed 20 mg Fe/kg MR and held unattached on rye straw litter or on sawdust or attached on wooden slatted floors without straw litter or were fed 50 mg Fe/kg MR and held unattached on sawdust. Fe concentrations in tested straw sorts (rye, barley, wheat, triticale) were similar and ranged from 15 to 85 mg Fe/kg dry matter. Growth performance and health status were not significantly influenced by Fe intake through MR or straw. Straw intake in the group fed straw was greater (P < 0.01) at the end than at the start of the growth period, but intake of different straw sorts was similar. Calves fed 20, but not those fed 50 mg Fe/kg MR, developed marked hypoferraemia, but only moderate anaemia. Total iron binding capacity (TIBC) was significantly (P < 0.05) and transferrin (Tf) concentration was numerically higher in calves fed 20 than in those fed 50 mg Fe/kg MR on slaughter day. TIBC and Tf were positively correlated (r = 0.63). Haemin concentration and lightness of m. rectus abdominis were significantly (P < 0.01), whereas myoglobin concentration was numerically greater in calves fed 50 than in those fed 20 mg Fe/kg MR. In conclusion, haematological and blood chemical parameters and meat colour were influenced only by high Fe intake through MR, but not if calves were held on straw litter or were fed straw.

The genomic structure of the human AP-2 transcription factor

The transcription factor AP-2 is encoded by a gene located on chromosome 6 near the HLA locus. Here we describe the genomic organization of the AP-2 gene including an initial characterization of the promoter. We have mapped two mRNA initiation sites, the entire exon-intron structure and located two polyadenylation sites. The mature AP-2 mRNA is spliced from 7 exons distributed over a region of 18 kb genomic DNA. A recently cloned inhibitory AP-2 protein is generated by alternative usage of a C-terminal exon. The proline-rich transactivation motif is encoded by a single exon within the N-terminal region in contrast to the complex DNA binding and dimerization motif which involves amino acid residues located on four different exons. The sites of mRNA initiation are located 220 and 271 bases upstream from the ATG translation start site. Although the promoter contains no canonical sequence motifs for basal transcription factors, such as TATA-, CCAAT- or SP-1 boxes, it mediates cell-type-specific expression of a CAT reporter gene in PA-1 human teratocarcinoma cells and is inactive in murine F9 teratocarcinoma cells. We demonstrate that the promoter of the AP-2 gene is subject to positive autoregulation by its own gene product. A consensus AP-2 binding site is located at position -622 with respect to the ATG. This site binds specifically to bacterially expressed AP-2 as well as to multiple proteins, including AP-2, present in PA-1 and HeLa cell nuclear extracts. A partial AP-2 promoter fragment including the AP-2 consensus binding site is approximately 5-fold transactivated by cotransfection of an AP-2 expression plasmid.

Recombinant expression and antigenic properties of a 32-kilodalton extracellular alkaline protease, representing a possible virulence factor from Aspergillus fumigatus

A 32-kDa nonglycosylated alkaline protease (EC 3.4.1.14) with elastolytic activity, secreted by the opportunistic pathogen Aspergillus fumigatus ATCC 42202, is suggested to be a virulence factor of this fungus. The enzyme is a serine protease of the subtilisin family, and its cDNA nucleotide sequence has recently been reported. We have cloned the cDNA encoding the mature protease into a high-level Escherichia coli expression plasmid and produced the recombinant protease as a fusion protein with a six-adjacent-histidine affinity tag at the carboxy terminus. Subsequently, the recombinant protease was purified to homogeneity, with affinity chromatography yielding 30 to 40 mg of recombinant protease per liter of E. coli culture. Refolded recombinant protease, in comparison with native protease, demonstrated weak enzymatic activity but similar immunochemical characteristics as analyzed by antigen-specific enzyme-linked immunosorbent assay (ELISA), competition ELISA, and immunoblotting assays. To assess the allergenic potential of the protease, sera from patients with allergic bronchopulmonary aspergillosis and sera from healthy control individuals were analyzed by ELISA and immunoblotting techniques. Sera from patients with allergic bronchopulmonary aspergillosis did not have protease-specific immunoglobulin E (IgE) antibodies and, remarkably, did not show significantly elevated protease-specific IgG antibody levels compared with those in sera from healthy control individuals. This suggests that the alkaline protease from A. fumigatus does not elicit IgE antibodies and has weak immunogenicity, a property which may explain fungus persistence in allergic individuals.

Murine dendritic cells pulsed in vitro with tumor antigen induce tumor resistance in vivo

The aim of this work is to induce tumor resistance to a B cell lymphoma in BALB/c mice using elements of the immune system. It has indeed been shown by us and by others that antigen-presenting cells (APC) like dendritic cells can induce efficient immune responses and can even substitute for Freund's adjuvant. Here we show that mice immunized with syngeneic dendritic cells pulsed in vitro with tumor antigen (BCL1 idiotype expressed by lymphoma cells) are protected against a subsequent tumor inoculation. The in vivo resistance can be correlated with the induction of a humoral response specific for the idiotype expressed by the tumor. No such protection can be achieved when B cells are used as APC. These data show that effector cells in tumor-bearing animals can be recruited and activated using dendritic cells, providing long-lasting immune surveillance.

Effect of diuretics on morbidity and mortality in the treatment of hypertension

Diuretic-based hypertension treatment trials have universally demonstrated a reduction in cardiovascular morbidity and mortality in treated compared with placebo or control subjects. Progression to more severe hypertension has been reduced together with reversal of left ventricular hypertrophy if present and prevention of congestive heart failure. The incidence of fatal and non-fatal strokes as well as coronary heart disease events have both been significantly reduced by diuretic-based treatment. Speculation that diuretic-induced adverse effects on lipid and glucose metabolism have negated the beneficial effects of blood pressure lowering has not been substantiated. Diuretics remain one of the preferred initial therapies in the management of hypertension.