Purification and characterization of bovine dendritic cells from peripheral blood

Optimal activation of T lymphocytes depends on TCR interaction with peptide/MHC complexes in conjunction with costimulatory signals, which are delivered by specialized cells called antigen-presenting-cells (APC). The population of APC is heterogeneous and includes dendritic cells, B cells and macrophages. The family of dendritic cells (DC) is widely distributed in tissues and plays a major role in the induction of primary T-dependent immune responses. The aim of this paper was to isolate and characterize dendritic cells from cattle. Two methods are described that have been used to isolate dendritic cells from bovine peripheral blood. One method involves sequential depletion of other cells, adherence and isolation of low buoyant density cells on Metrizamide column. The second involves enrichment of cells displaying receptors for plasma fibronectin, followed by adherence and separation on Metrizamide. Both preparations were characterized morphologically by flow cytometry and functionally. Both procedures produced enriched populations that did not express molecules typical of T cells (CD3, CD4, CD8, WC1), B cells (sIg, CD21) and monocytes (CD14, Fc gamma 2R). Procedure 2 yielded cells with a typical veiled DC morphology that were highly effective at stimulating allogeneic T cells. Procedure 1 yielded cells that did not have the veiled morphology and were less effective in the MLR which may represent a more immature stage.

Clinical trial results with a new plasminogen activator

Thrombolysis has become an accepted form of therapy for acute myocardial infarction. As demonstrated in the Global Utilization of Streptokinase and t-PA for Occluded Arteries trial, early, complete and sustained patency of the infarct-related coronary artery is correlated with reduced mortality. However, current thrombolytic regimens are able to achieve such patency within 90 min in only 81% of cases. To improve the risk/benefit ratio of thrombolytic therapy, newer agents such as reteplase have been developed to establish more rapid, more complete and more stable coronary artery patency, thus reducing mortality. This report summarizes the pharmacological properties of reteplase. It also summarizes the findings from various animal and clinical studies in which reteplase was compared with alteplase and streptokinase and the findings from animal and clinical studies evaluating infusion, single-bolus, double-bolus, doses of reteplase.

Major depression and cardiac autonomic control

We investigated autonomic control of heart rate in patients with major depression, melancholic type. Twenty-three depressed inpatients who were being treated with tricyclic antidepressants and 23 depressed patients who were taking no medications were compared with age- and sex-matched control groups on resting cardiac vagal tone and heart rate. In unmedicated depressed patients, cardiac vagal tone was comparable to that of control subjects, but heart rate was significantly higher. This increase in heart rate may have been due to sympathetic activation caused by anxiety, since the depressed patients were significantly more anxious than the control subjects. Medicated patients exhibited diminished cardiac vagal tone and higher heart rate than unmedicated patients and controls. This was probably due to the anticholinergic effects of the antidepressants. Our findings suggest that cardiac vagal tone is not lower than normal in patients with depression, melancholic type.

Prion (PrPSc)-specific epitope defined by a monoclonal antibody

Prions are infectious particles causing transmissible spongiform encephalopathies (TSEs). They consist, at least in part, of an isoform (PrPSc) of the ubiquitous cellular prion protein (PrPC). Conformational differences between PrPC and PrPSc are evident from increased beta-sheet content and protease resistance in PrPSc. Here we describe a monoclonal antibody, 15B3, that can discriminate between the normal and disease-specific forms of PrP. Such an antibody has been long sought as it should be invaluable for characterizing the infectious particle as well as for diagnosis of TSEs such as bovine spongiform encephalopathy (BSE) or Creutzfeldt-Jakob disease (CJD) in humans. 15B3 specifically precipitates bovine, murine or human PrPSc, but not PrPC, suggesting that it recognizes an epitope common to prions from different species. Using immobilized synthetic peptides, we mapped three polypeptide segments in PrP as the 15B3 epitope. In the NMR structure of recombinant mouse PrP, segments 2 and 3 of the 15B3 epitope are near neighbours in space, and segment 1 is located in a different part of the molecule. We discuss models for the PrPSc-specific epitope that ensure close spatial proximity of all three 15B3 segments, either by intermolecular contacts in oligomeric forms of the prion protein or by intramolecular rearrangement.

Enhanced apoptotic cell death of renal epithelial cells in mice lacking transcription factor AP-2beta

Expression of AP-2 transcription factors has been detected previously in embryonic renal tissues. We show here that AP-2beta -/- mice complete embryonic development and die at postnatal days 1 and 2 because of polycystic kidney disease. Analyses of kidney development revealed that induction of epithelial conversion, mesenchyme condensation, and further glomerular and tubular differentiation occur normally in AP-2beta-deficient mice. At the end of embryonic development expression of bcl-X(L), bcl-w, and bcl-2 is down-regulated in parallel to massive apoptotic death of collecting duct and distal tubular epithelia. Addressing the molecular mechanism we show that transfection of AP-2 into cell lines in vitro strongly suppresses c-myc-induced apoptosis pointing to a function of AP-2 in programming cell survival during embryogenesis. The position of the human AP-2beta gene was identified at chromosome 6p12-p21.1, within a region that has been mapped for autosomal recessive polycystic kidney disease (ARPKD). Sequence analyses of ARPKD patients and linkage analyses using intragenic polymorphic markers indicate that the AP-2beta gene is located in close proximity to but distinct from the ARPKD gene.

Reteplase (r-PA): a new plasminogen activator

Reteplase (r-PA) is a genetically engineered deletion mutant of wild-type tissue-type plasminogen activator. The structural differences lead to different functional properties, such as a prolonged half-life. The compound demonstrated good thrombolytic efficacy in in vitro as well as in animal studies. In angiographically controlled patency studies (GRECO, GRECO-2 RAPID-1, RAPID-2), the double-bolus application scheme was established, and a superior patency profile for reteplase in comparison to alteplase was demonstrated. Mortality studies established reteplase as a safe drug with a 30-day mortality at least equivalent to streptokinase (INJECT) and very similar to alteplase (GUSTO-3). A possible advantage may be the double-bolus application without a need for weight adjustment, especially in a prehospital setting. Thus, reteplase can be regarded as an excellent alternative to streptokinase or alteplase for thrombolytic therapy in acute myocardial infarction.

Effects of an eight-day space flight on microvibration and physiological tremor

Microgravity was used to study accelerometrically recorded microvibration (MV) and postural tremor (PT) at reduced muscle tone on one cosmonaut before, during, and after an 8-day space flight on the Russian Mir station. MV of the relaxed forearm in the 1 g environment showed the typical 7- to 13-Hz resonance oscillations triggered by the heart beat. In 0 g, these pulsations shifted to below 5 Hz and the waveform became similar to an ultralow frequency acceleration ballistocardiogram. PT of the arm stretched forward showed an irregular waveform in 1 g. In 0 g, the higher-frequency components were reduced and again an ultralow frequency ballistocardiogram emerged. As a control, hand force tremor was recorded as well; it was not affected by the gravity condition. A second-order analog with muscle stiffness (C) as parameter was used to evaluate the measurements. For MV it could be shown that cardiac impacts produce damped resonance oscillations when C is high enough (1 g). At low C (0 g), this resonance phenomenon is essentially filtered out. For PT both neuromuscular and cardiovascular forces produce an irregular output; when C is lowered (0 g) the higher-frequency content is strongly reduced. It is concluded that both MV and PT waveforms are sensitive to musculoskeletal stiffness, such that at the lowest stiffness achieved the cardiac impact dominates. In 1 g, the cosmonaut's data were not significantly different from the results in a control group (n = 6).

Angiotensin-converting enzyme inhibitors, angiotensin II receptor antagonists and calcium channel blocking agents: a review of potential benefits and possible adverse reactions

A review of recent studies suggests that the use of angiotensin-converting enzyme (ACE) inhibitors may be preferred (usually along with a diuretic drug) as initial therapy in several subsets of hypertensive patients (i.e., those with diabetes and nephropathy or with diminished left ventricular function with or without symptoms of heart failure). Limited long-term data are available for the angiotensin II receptor antagonists. The use of nondihydropyridine calcium channel blocking agents (CCBs) appears to reduce reinfarction in patients with ischemic heart disease (however, mortality is not reduced). Long-acting formulas of CCBs appear to decrease congestive heart failure in patients with dilated, but not ischemic, cardiomyopathy and to decrease strokes and arrhythmias in hypertensive subjects. Short-acting agents (primarily those that increase heart rate) may increase coronary heart disease events in hypertensive patients. There is little evidence at present that CCBs offer a major advantage over other antihypertensive agents or that they should be recommended as initial therapy, except in special situations.

Diuretics in the prevention and treatment of congestive heart failure

Diuretics, either as monotherapy or in combination with other drugs in the management of hypertension, have retarded the development of left ventricular hypertrophy and congestive heart failure in many patients. Diuretics also remain one of the most effective therapies in the treatment of congestive heart failure, when given with an ACE inhibitor and digoxin.

Effect of interleukin-10 on dendritic cell maturation and function

The main function of dendritic cells (DC) is to induce the differentiation of naive T lymphocytes into helper cells producing a large array of lymphokines, including interleukin (IL)-2; interferon-gamma (IFN-gamma), IL-4, IL-5 and IL-10. The potent immunostimulatory properties of DC develop during a process of maturation that occurs spontaneously in vitro. Since IL-10 has been shown to inhibit Th1 responses, we determined its effect on DC maturation and accessory function. Our data show that DC that have undergone maturation in vitro in the presence of IL-10, have an impaired capacity to induce a Th1-type response in vivo, leading to the development of Th2 lymphocytes. Their inability to promote the synthesis of IFN-gamma seems to correlate with a decreased production of IL-12, an heterodimeric cytokine necessary for optimal generation of Th1-type cells. These results suggest that IL-10 skews the Th1/Th2 balance to Th2 in vivo by selectively blocking IL-12 synthesis by the antigen-presenting cells that play a role of adjuvant of the primary immune response. The cytokines present in the environment at the presentation step may, therefore, determine the class of the immune response induced by DC in vivo, i.e. Th0, Th1 and/or Th2.

Broadly tunable femtosecond Cr:LiSAF laser

We demonstrate wavelength tunability of femtosecond pulses over a range of more than 50 nm from a diode-pumped Cr:LiSAF laser. The mode-locking mechanism can be explained by soliton mode locking that is started and stabilized by a broadband semiconductor saturable-absorber mirror designed for low loss over the full reflection bandwidth of the underlying Bragg mirrors, which ultimately limits tunability. We obtain 45-fs pulses at 105-mW average output power and a maximum mode-locked average output power of 125 mW with 60-fs pulses.

Mouse CD-RAP/MIA gene: structure, chromosomal localization, and expression in cartilage and chondrosarcoma

A cDNA encoding a novel protein has been previously isolated from two independent sources: melanoma cell cultures and chondrocytes. The protein from human melanoma cell lines and tumors is called melanoma inhibitory activity (MIA) (Blesch et al. [1994] Cancer Res. 54:5695-5701) and the protein from primary bovine chondrocytes and cartilaginous tissues is called cartilage-derived retinoic acid-sensitive protein (CD-RAP) (Dietz and Sandell [1996] J. Biol. Chem. 271:3311-3316). In order to investigate the gene regulation and function of CD-RAP/MIA, the mouse gene locus was isolated and analyzed. Developmental expression was determined by in situ hybridization to mouse embryos. Expression was limited to cartilaginous tissues and was initiated with the advent of chondrogenesis, remaining abundant throughout development. The mouse gene was isolated and sequenced from a 129Sv library and sequenced directly from an additional strain, B6C3Fe. The mouse CD-RAP/MIA gene is 1.5 kbp and consists of four exons. The promoter sequence of the gene contains many potential regulatory domains including 8 basic helix-loop-helix protein-binding domains and an AT-rich domain, both motifs shown to be present in the cartilage-specific enhancer of the type II procollagen gene. Other potential cis-acting motifs include binding sites for GATA-1, NF-IL6, PEA3, w-elements, NF kappa B, Zeste and Sp1. The gene, called cdrap, was localized to the end of an arm of chromosome 7 at the same site as the transforming growth factor beta 1 (Tgf-beta 1) and the glucose phosphate isomerase 1 (Gpi 1) genes. Potential mouse mutants that mapped to the same region of chromosome 7 were identified. Two of the potential mutants with skeletal phenotypes were sequenced, pudgy (pu) and extra toes with spotting (XsJ); however, no mutations were found in the coding sequence. To determine whether CD-RAP/MIA is associated with tumors of cartilage, mRNAs from a variety of rodent tissues and cell lines were screened. Expression was detected in a rodent tumor, the Swarm rat chondrosarcoma and a chondrosarcoma cell line derived from it, but not in other tissues or tumors of non-cartilage origin. Immunolocalization revealed CD-RAP/MIA protein localized in cartilage only. These results show that the normal expression of CD-RAP/MIA is limited to cartilage; however, pathologically, it is expressed both in melanoma and chondrosarcoma. The restricted expression of CD-RAP/MIA may provide an opportunity to monitor cartilage metabolic activity as well as the tumor activity of melanoma and chondrosarcoma.

Staphylococcal enterotoxin B induces an early and transient state of immunosuppression characterized by V beta-unrestricted T cell unresponsiveness and defective antigen-presenting cell functions

Staphylococcal enterotoxin B (SEB) is a bacterial enterotoxin able to simultaneously bind to class II molecules on APCs and to selected V beta regions (including V beta 8) of the TCR complex. Administration of SEB to adult BALB/c mice results in clonal activation of T cells bearing V beta 8 receptors, leading to an excessive release of proinflammatory cytokines. This initial immune response is followed by a long-lasting state of V beta 8-specific unresponsiveness, thought to benefit both the host (as it contributes to the down-regulation of the inflammatory response) and the bacterium (through ligand-specific T cell anergy). However, it is not clear how this type of restricted unresponsiveness can effectively impair the generation of an antibacterial response. To gain insight into the mechanism by which Gram-positive bacteria subvert the host immune response, we have investigated the immune competence of SEB-treated mice 48 h following SEB administration. We demonstrate in this report that in vivo, SEB induces a transient but profound state of unresponsiveness affecting both T and Ag-presenting cell functions. Although in vivo activation by SEB appears to be V beta-restricted under our experimental conditions, SEB-treated mice displayed an early (lasting 48 to 72 h postinjection) and V beta-unrestricted unresponsive state characterized by the inability to produce IL-2 in response to polyclonal TCR mitogens including third party bacterial superantigens (staphylococcal enterotoxin A and toxic shock syndrome toxin 1, SEA and TSST-1, respectively), Abs to non-SEB reactive V beta regions (V beta 6), anti-CD3 epsilon Abs, and a lectin (Con A). Spleen cell populations from SEB-treated mice also displayed defective APC functions, possibly related to a selective decrease in splenic dendritic cells numbers. Taken together, these observations indicate that SEB induces an early and transient state of immunodeficiency in vivo, representing a potential mechanism for escaping host immune surveillance.

56-ps passively Q-switched diode-pumped microchip laser

We passively Q switched a diode-pumped Nd:YVO4 microchip crystal with an antiresonant Fabry-Perot saturable absorber and achieved single-frequency pulses as short as 56 ps. We can vary the pulse width from 56 ps to 30 ns and the repetition rate from 27 kHz up to 7 MHz by changing the design parameters of the saturable absorber and the pump power.

Staphylococcal enterotoxin B induces an early and transient state of immunosuppression characterized by V beta-unrestricted T cell unresponsiveness and defective antigen-presenting cell functions

Staphylococcal enterotoxin B (SEB) is a bacterial enterotoxin able to simultaneously bind to class II molecules on APCs and to selected V beta regions (including V beta 8) of the TCR complex. Administration of SEB to adult BALB/c mice results in clonal activation of T cells bearing V beta 8 receptors, leading to an excessive release of proinflammatory cytokines. This initial immune response is followed by a long-lasting state of V beta 8-specific unresponsiveness, thought to benefit both the host (as it contributes to the down-regulation of the inflammatory response) and the bacterium (through ligand-specific T cell anergy). However, it is not clear how this type of restricted unresponsiveness can effectively impair the generation of an antibacterial response. To gain insight into the mechanism by which Gram-positive bacteria subvert the host immune response, we have investigated the immune competence of SEB-treated mice 48 h following SEB administration. We demonstrate in this report that in vivo, SEB induces a transient but profound state of unresponsiveness affecting both T and Ag-presenting cell functions. Although in vivo activation by SEB appears to be V beta-restricted under our experimental conditions, SEB-treated mice displayed an early (lasting 48 to 72 h postinjection) and V beta-unrestricted unresponsive state characterized by the inability to produce IL-2 in response to polyclonal TCR mitogens including third party bacterial superantigens (staphylococcal enterotoxin A and toxic shock syndrome toxin 1, SEA and TSST-1, respectively), Abs to non-SEB reactive V beta regions (V beta 6), anti-CD3 epsilon Abs, and a lectin (Con A). Spleen cell populations from SEB-treated mice also displayed defective APC functions, possibly related to a selective decrease in splenic dendritic cells numbers. Taken together, these observations indicate that SEB induces an early and transient state of immunodeficiency in vivo, representing a potential mechanism for escaping host immune surveillance.

60-fs pulses from a diode-pumped Nd:glass laser

We demonstrate 60-fs pulses with an average output power of 84 mW from a diode-pumped Nd:glass laser mode locked by a low-finesse antiresonant Fabry-Perot saturable absorber (A-FPSA). The mode-locked spectrum spreads over most of the available Nd:glass fluorescence bandwidth. At increased pulse energy fluence or decreased negative group-velocity dispersion, multiple pulsing was observed. We experimentally characterize this behavior, which can be explained by the saturation behavior of the A-FPSA and the limited available gain bandwidth. These considerations are significant for the design of saturable absorbers to achieve stable passive mode locking.