Epidemiological significance of cutaneous, pharyngeal, and digestive tract colonization by multiresistant Acinetobacter baumannii in ICU patients

The aim of this prospective study was to assess the relative epidemiological role of digestive tract colonization by Acinetobacter baumannii, in comparison with other body site colonizations, in patients admitted to intensive care units (ICUs). From January to May 1995, axillary, pharyngeal and rectal swabs were taken together within the first 48 h of admission, and then weekly during ICU stay. Seventy-three patients were included, 48 of them (66%) had axillary, pharyngeal, or rectal colonization with A. baumannii, nine (19%) of these 48 during the first 48 h and the remaining 28 (77%) during the first week. Twenty-one (29%) had clinical samples positive for A. baumannii and axillary, pharyngeal, or rectal colonization. In 15 of these 21 (71%), colonization on body sites occurred prior to isolation from clinical samples (mean seven days, range 1-20). Throughout admission, rates of detection of A. baumannii were 75% (36/48) for axillary or pharyngeal swabs and 77% (37/48) for rectal swabs. Combination of two body site swabs yielded culture positive rates of 90% (43/48) for axillary-pharyngeal or axillary-rectal sites, and 96% (46/48) for pharyngeal-rectal. Two epidemic clones were defined by antibiotype and pulsed-field gel electrophoresis (PFGE) of SmaI DNA digests in 48 isolates from 11 patients. We conclude that body sites of patients were a major reservoir for A. baumannii infections in the outbreak. This finding cases doubt on the value of selective decontamination of the digestive tract as an additional infection control measure in this kind of outbreak. The weekly performance of pharyngeal and rectal swabs appears to detect A. baumannii colonization early among ICU patients and enables barrier methods to be applied rapidly.

Childhood hearing impairment: processing dependencies in multidimensional speech perception for an auditory level of analysis

OBJECTIVE

Our purpose was to determine whether the influence of childhood hearing impairment (HI) on multidimensional speech processing is a purely linguistic effect or whether childhood HI also affects the processing of speech dimensions representing an auditory level of analysis.

DESIGN

The processing dependencies characterizing the two dimensions of talker-gender and spatial location were studied in 40 children with HI and in two normal-hearing (NH) comparison groups representing similar chronological ages (N = 30) or similar vocabulary skills (N = 70). The processing interactions were assessed with a speeded selective-attention task requiring listeners to attend selectively to the gender of the talker and to ignore the spatial location and vice versa. The logic is that performance for the target dimension will not be affected by what is happening on the nontarget dimension if the dimensions are processed independently. On the other hand, if the dimensions are not processed independently, listeners will not be able to attend selectively and performance for the relevant dimension will be affected by what is happening on the irrelevant dimension. In the latter case, results may be analyzed in terms of Garner interference (the effect on performance of irrelevant variability in the to-be-ignored dimension) (Garner, 1974a) and Simon interference (the effect on performance of an irrelevant spatial source) (Simon, 1990).

RESULTS

Overall results in all listeners, those with NH or HI, showed significant interference when the participants were attending to the gender of the talker and ignoring spatial location and vice versa. The talker-gender and spatial-location dimensions of speech were not processed independently by these children. When the processing interactions were compared between the NH and HI groups, the presence of childhood HI as a general rule significantly diminished the degree of interference from spatial location. The degree of interference from the gender of the talker, on the other hand, remained normal in the presence of childhood HI. All listeners seemed stimulus bound by the gender of the talker. The degree of Garner interference did not show age-related or degree of loss-related change. The degree of Simon interference showed significant change as a function of age in the children with mild-moderate HI, but not in the children with severe HI. The developmental function for Simon interference in the children with mild-moderate HI was delayed to a degree that corresponded to the duration of the auditory deprivation.

CONCLUSIONS

The overall pattern of results indicates that the influence of childhood HI on multidimensional speech processing is not a purely linguistic effect.

Paternal age effect of YY aneuploidy in human sperm, as assessed by fluorescence in situ hybridization

Sperm samples were collected from 18 healthy men of various ages. Multicolor FISH was performed on each sample, using probes for the sex chromosomes and chromosome 1. A minimum of 10,000 sperm per donor was analyzed. The Pearson correlation coefficient was used to determine if there was an association between donor age and disomy frequency for the sex chromosomes.

CT-guided core-needle biopsy in omental pathology

PURPOSE

To assess the accuracy and clinical usefulness of CT-guided core-needle biopsy in the diagnosis of omental pathology.

MATERIAL AND METHODS

We retrospectively reviewed the results of CT-guided percutaneous core biopsies in 25 patients with focal (n = 2) or diffuse (n = 23) omental pathology. These results were compared to the final diagnoses as determined by laparotomy (n = 15), laparoscopic biopsy (n = 3), endoscopic biopsy (n = 1), or by the results of percutaneous biopsy and clinical-radiological and bacteriological modalities (n = 6). The final diagnoses showed 4 patients with isolated omental pathology and 21 with widespread peritoneal involvement. The CT-guided biopsies were performed with 1.0-1.8-mm Surecut core-needles.

RESULTS

In 16 patients, the final diagnosis was metastatic adenocarcinoma--with the primary tumor sites in the ovary (n = 3), stomach (n = 1), appendix (n = 2), and unknown (n = 10). In the remaining 9 patients, the final diagnosis was hepatocellular carcinoma, lymphoma, and mesothelioma in 1 patient each; tuberculosis in 5; and actinomycosis in 1. Sufficient histological (n = 16) or cytological (n = 8) material was obtained by CT biopsy in 24/25 (96%) cases; the specimen was insufficient for diagnosis in 1 case. In differentiating benign from malignant disease, CT-guided biopsy showed a sensitivity, specificity and accuracy of respectively 89.5%, 100% and 92%. It gave a specific diagnosis in 78.9% (15/19) of patients with malignant conditions and in 50% (3/6) of patients with benign disorders. There were no biopsy-related complications.

CONCLUSION

CT-guided percutaneous core-needle biopsy of the omentum is a safe, useful and highly accurate procedure for diagnosing malignant omental pathology.

Detection of low phosphorus contents in neurofilaments of squid axons by Image-EELS contrast spectroscopy

We show that Image-EELS is suitable for detecting relatively low phosphorus concentrations in very small axoplasmic structures of squid axons. Imaging plates and a CCD camera were used as electron sensors. From image series spanning a certain energy-loss range EELS (electron energy-loss spectra) were derived by averaging read-outs from many axoplasmic particles (APs). The ratio of these spectra to spectra of the background was plotted, showing the contrast modulation as a function of the energy loss. This new approach is called EELC (electron energy-loss-dependent contrast spectroscopy). A distinct phosphorus signal was found in APs of presynaptic terminals of the squid giant synapse, in the peripheral giant axon and, as controls, in ribosomes. Biochemical experiments supported this result. In neurofilament-enriched pellets a phosphorus signal could be directly detected by serial EELS and in electron spectroscopic micrographs. After dephosphorylation of either the pellets or the extruded axoplasm with alkaline phosphatase, phosphorus signals in electron spectroscopic micrographs were absent or much reduced in size and intensity. With Image-EELS inherent limitations of traditional element detection modes in energy filtering transmission electron microscopy can be overcome. Compared with serial EELS, the selective analysis of small areas with irregular shape is possible with greatly improved signal-to-noise ratio. The identification of the element-peak in Image-EEL spectra directly proves the presence of the element within the region of interest. For small peaks, the visualization is facilitated by the contrast presentation (EELC). However, the background subtraction modes used for elemental mapping in electron spectroscopic imaging are subject to uncertainties when elemental ionization edges like the P1,2,3 edge are examined. Imaging plates are very sensitive electron sensors with a wide dynamic range. Unlike photographic emulsions, they allow acquisition of image series covering a large energy-loss range without normalization of exposure times, and direct extraction of EEL spectra. Thus, the combination of Image-EELS and imaging plates is proposed as an efficient new tool for analytical electron microscopy.

Retroviral gene transfer into porcine keratinocytes following improved methods of cultivation

We embarked on a program examining the application of cultured epithelial sheets to skin wounds in pigs using retroviral gene transfer as a means to follow the grafted cells. In the past similar studies have been hampered by an inability to grow porcine keratinocytes without seeding at an extremely high density. In this study we found that excellent results could be achieved with Opti-MEM-1 (Gibco BRL Life Technologies) containing 1 per cent foetal calf serum, 0.5 mM Ca2+ and no other growth factors or stimulants. Keratinocytes were plated on gamma-irradiated 3T3 feeders on surfaces which had previously been coated with rat tail collagen I. Keratinocyte cultures were established at a seeding density of 5 x 10(4) cm-2. The yield of cells from 1 cm2 of skin was sufficient to set up a 75 cm2 flask. Cultures reached 80-90 per cent confluence in 7-10 days, after which they were passaged 1:3 multiple times, taking 3-4 days to reach the same confluency. Allowing cultures to remain confluent for 1 week was sufficient to allow Dispase removal of an intact sheet. Using these techniques porcine keratinocytes were transduced at an average frequency of 25.3 per cent (+/- 14.0 SEM) with the retroviral vector MFG lacZ nls by growth on the gamma-irradiated retroviral producer line GP + envAm12.

Active polysomes are present in the large presynaptic endings of the synaptosomal fraction from squid brain

Previous data have suggested that the large nerve terminals present in the synaptosomal fraction from squid optic lobe are capable of protein synthesis (Crispino et al., 1993a,b). We have further examined this issue by comparing the translation products of synaptosomal and microsomal polysomes. Both preparations programmed an active process of translation, which was completely abolished by their previous treatment with EDTA. After immunoabsorption of the newly synthesized neurofilament (NF) proteins, the labeling ratio of the 60 and 70 kDa NF proteins was found to differ, in agreement with comparable differences obtained with intact synaptosomes. These observations indicate that the set of mRNAs translated by synaptosomes differs from that translated by nerve cell bodies. Hence, because NF proteins are neuron-specific, they support the view that the active synaptosomal polysomes are mostly localized in the large nerve terminals that represent the most abundant neuronal component of the fraction. This hypothesis was confirmed (1) by electron spectroscopic data demonstrating the presence of ribosomes and polysomes within the large nerve endings of the synaptosomal fraction, as well as in the carrot-like nerve endings of the retinal photoreceptors that constitute the only large terminals in the optic lobe, and (2) by light and high resolution autoradiography of synaptosomal samples incubated with [3H]leucine, showing that most labeled proteins are associated with the large nerve endings. This response was abolished by cycloheximide. Taken together, the data provide the first unequivocal demonstration that presynaptic nerve terminals are capable of protein synthesis.

Human T-cell response to myelin basic protein peptide (83-99): extensive heterogeneity in antigen recognition, function, and phenotype

Multiple sclerosis (MS) is considered a T cell-mediated autoimmune disease, and myelin proteins are the most likely candidate autoantigens. Based on experiments performed in experimental allergic encephalomyelitis (EAE), innovative immunotherapies have been developed that target either the specific trimolecular complex of encephalitogenic T cells, consisting of T-cell receptor (TCR), major histocompatibility complex (MHC; HLA in humans) class II molecule, and autoantigenic peptide, or the effector functions of these cells. To provide the basis for the transfer of these specific immunotherapies to MS, we extensively characterized the human T-cell response to one major myelin epitope, the myelin basic protein peptide (83-99). We analyzed restriction element, TCR usage and affinity, fine specificity, cytokine production, cytolytic activity, and expression of surface molecules on 41 T-cell clones (TCCs) derived from MS patients and normal controls. We demonstrate a high degree of complexity of recognition patterns as well as of functional phenotypes among T cells responding to the same epitope. In contrast to results from animal models, these findings indicate that the design of epitope-based specific immunotherapies for MS is more difficult than previously thought.

Therapeutic potential of phosphodiesterase type 4 inhibition in chronic autoimmune demyelinating disease

It was recently demonstrated that selective phosphodiesterase type 4 (PDE4) inhibition suppresses the clinical manifestations of acute experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS), and inhibits the production of tumor necrosis factor-alpha (TNF-alpha), a pathogenetically central cytokine. Since the most common presentation of MS in humans is a relapsing-remitting course, we investigated the therapeutic potential of PDE4 inhibition in the relapsing-remitting EAE model of the SJL mouse. Administration of rolipram, the prototypic PDE4 inhibitor, reduced the clinical signs of EAE during both the initial episode of disease and subsequent relapses. In parallel, there was marked reduction of demyelination and also less inflammation throughout the central nervous system (CNS) of rolipram-treated animals. Gene expression of proinflammatory cytokines in the CNS was reduced in most of the rolipram-treated animals. Additional experiments demonstrated that PDE4 inhibition acted principally by inhibiting the secretion of Th1 cytokines, however, the encephalitogenic potential of myelin basic protein-specific T cells was not impaired. Our findings suggest that PDE4 inhibitors are a promising cytokine-directed therapy in chronic demyelinating disease.

Human autoreactive and foreign antigen-specific T cells resist apoptosis induced by soluble recombinant CD95 ligand

Mature T cells are susceptible to activation-induced cell death in the periphery. Activation-induced cell death is thought to involve CD95/CD95 ligand interactions in vivo. Here we report that stimulated, CD45RO+ human T cell lines specific for myelin basic protein or tetanus toxoid from multiple sclerosis patients and healthy individuals resist apoptosis induced by soluble recombinant CD95 ligand in vitro. In contrast, the same CD95 ligand effectively kills Jurkat T lymphoma and human malignant glioma cells. The resistance of the T cell lines is not due to a lack of CD95 expression at the cell surface and is not overcome by coexposure to CD95 ligand and inhibitors of RNA or protein synthesis. The expression level of BCL-2 is lower in Jurkat than in Ag-specific T cells. After exposure to soluble CD95 ligand, Jurkat T cells, but not Ag-specific T cells, exhibit loss of BCL-2 and BCL-X expression whereas BAX expression is not affected. Surprisingly, Ag-specific T cells are rather sensitive to CD95 ligand expressed at the cell surface of N2A neuroblastoma cells. Accessory molecules expressed by the CD95 ligand-expressing effector cell are dispensable for apoptosis since the T cells are equally sensitive to agonistic APO-1 Ab. Further studies are required to determine whether resistance to soluble CD95 ligand-mediated apoptosis is a possible escape mechanism for T cells from peripheral deletion that may have relevance for autoimmune disorders.

Human autoreactive and foreign antigen-specific T cells resist apoptosis induced by soluble recombinant CD95 ligand

Mature T cells are susceptible to activation-induced cell death in the periphery. Activation-induced cell death is thought to involve CD95/CD95 ligand interactions in vivo. Here we report that stimulated, CD45RO+ human T cell lines specific for myelin basic protein or tetanus toxoid from multiple sclerosis patients and healthy individuals resist apoptosis induced by soluble recombinant CD95 ligand in vitro. In contrast, the same CD95 ligand effectively kills Jurkat T lymphoma and human malignant glioma cells. The resistance of the T cell lines is not due to a lack of CD95 expression at the cell surface and is not overcome by coexposure to CD95 ligand and inhibitors of RNA or protein synthesis. The expression level of BCL-2 is lower in Jurkat than in Ag-specific T cells. After exposure to soluble CD95 ligand, Jurkat T cells, but not Ag-specific T cells, exhibit loss of BCL-2 and BCL-X expression whereas BAX expression is not affected. Surprisingly, Ag-specific T cells are rather sensitive to CD95 ligand expressed at the cell surface of N2A neuroblastoma cells. Accessory molecules expressed by the CD95 ligand-expressing effector cell are dispensable for apoptosis since the T cells are equally sensitive to agonistic APO-1 Ab. Further studies are required to determine whether resistance to soluble CD95 ligand-mediated apoptosis is a possible escape mechanism for T cells from peripheral deletion that may have relevance for autoimmune disorders.

Nitric oxide production in burns: plasma nitrate levels are not increased in patients with minor thermal injuries

BACKGROUND

Recent studies have suggested that adults who sustain burns of less than 15% total body surface area display elevated plasma nitrate levels, indicating increased production of nitric oxide. The present study was initiated to confirm whether plasma nitrate is elevated in minor burn injury and, if so, whether it heralds the onset of a systemic inflammatory response to that injury.

METHODS

Plasma samples were taken from 98 control and 10 burns patients.

RESULTS

The mean plasma nitrate level for nine burns patients with a mean total body surface area burnt of 7.65% (range, 4-15%) was 42.83 micromol/L on day 1. This was not significantly different from that of a control population of 98 preoperative plastic surgery patients: 36.91 micromol/L (p = 0.162). Eight of 10 burns patients showed a decrease in plasma nitrate to 27.47 micromol/L by day 3 (p = 0.046). Elevated nitrate levels were seen in 2 of 10 burns patients. One had concurrent smoke-inhalation injury preceding multiple organ dysfunction, and one was treated with a cream containing cerium nitrate (Flammacerium, Duphar Laboratories, Southhampton, United Kingdom).

CONCLUSIONS

For patients who sustain minor burns, plasma levels of nitrate decrease from those of mean normal controls with time unless there is multiple organ dysfunction or the patient receives extraneous nitrate.

Videodensitometric analysis of electron spectroscopic micrographs--a tool for detection of biologically relevant elements with high resolution

Electron energy-loss spectroscopic imaging (ESI) yields high-resolution, element-sensitive images. However, ESI suffers from difficulties in distinguishing element-specific and background contributions. New methods have therefore been introduced which use grey-level measurements in micrographic images for a more accurate detection of element distributions. A videodensitometric method allowed the detection of low phosphorus levels in axoplasmic neurofilaments of squid giant axons. Here we further verify these results by investigating the relationship of videodensitometry and electron energy-loss spectroscopy (EELS), particularly considering the peculiarities of these methods in terms of automatic background correction and representation of the results. Six biological specimens and two nonbiological specimens were examined both by EELS and by videodensitometry. In all cases comparable results were obtained. The overlapping PL2,3 and SL2,3 ionization edges could clearly be recognized individually by both methods, and controls showed that mass density variations within the specimens did not impair elemental analysis. Additional evidence supporting the detection of phosphorylation sites in squid neurofilaments was obtained in both EELS and videodensitometric measurements of neurofilament-enriched pellets and of aggregated axoplasmic particles. Thus, video-densitometry appears to be a useful tool for an improved exploration of the full imaging capabilities of energy filtering electron microscopy.

Genetic relatedness of Burkholderia (Pseudomonas) cepacia isolates from five cystic fibrosis centers in Michigan

Burkholderia cepacia isolates from patients with cystic fibrosis (CF) attending five CF centers were studied for relatedness by cellular fatty acid methyl esters (FAME) and by chromosomal DNA restriction analysis. Twenty-eight of 32 (87.5%) isolates tested were grouped in cluster group 1 based on their FAME profiles. DNA analysis revealed that 29 of 32 (90.6%) B. cepacia isolates from five CF centers had one closely related DNA pattern. To examine strain variation over a time period, FAME profiles and DNA patterns of isolates from serial cultures on seven patients from center D were studied. For four patients, all serial B. cepacia isolates belonged to a single FAME cluster group; for the remaining three patients, all serial isolates belonged to any two of the four cluster groups. On serial culture isolates, a single DNA pattern (pattern A) was found in 31 of 32 isolates demonstrating a close genetic relatedness. These data corroborate the observations that the majority of patients colonised with B. cepacia in a CF center harbor strains genetically closely related as determined by FAME profiles and DNA patterns.

Longitudinal study of myelin basic protein-specific T-cell receptors during the course of multiple sclerosis

This study analyzed the stability of the myelin basic protein (MBP)-specific T-cell receptor (TCR) repertoire during the course of multiple sclerosis (MS) in three patients who were monitored for three years by gadolinium-enhanced magnetic resonance imaging. Bulk-culture T-cell lines (TCLs) were generated from 3-4 time points for each patient, including times of active and quiescent disease. TCR analysis of these TCLs indicated that both the V alpha and V beta usage was similar over time for each patient. Sequencing of TCRs demonstrated conserved complementarity-determining region 3 (CDR3) sequences within TCLs that expressed the same V alpha segment over time, although the J alpha usage was different for each TCR. This indicates that the population of MBP-reactive T-cells is changing during the course of MS, but that host and/or environmental factors may be selecting T-cells with particular MHC/peptide binding domains.

Tumor-associated proteolytic factors uPA and PAI-1 in endometrial carcinoma

The levels of plasminogen activator urokinase (uPA) and of its inhibitor (PAI-1) were measured by use of ELISA in the cytosol of tissue homogenates obtained from endometrial carcinomas and the marginal, tumor-free endometrium of postmenopausal patients (n = 64). Significantly higher median levels of uPA and PAI-1 were found in malignant endometrium (uPA 1.89 ng/mg, PAI-1 3.04 ng/mg) compared to tumor-free endometrium (uPA 0.84 ng/mg, PAI-1 1.01 ng/mg). Concerning uPA, no significant differences were found in dependence on histomorphological prognostic factors (staging, grading), but the median level of PAI-1 was significantly higher in G2/G3 carcinomas compared to G1 tumors (5.08 ng/mg vs 2.19 ng/mg). Because of the good prognosis of operated patients with endometrial carcinomas, the prognostic value of uPA and PAI-1 can only be decided by a larger number of patients and a long observation time.

Differential expression of cyclic nucleotide phosphodiesterase 3 and 4 activities in human T cell clones specific for myelin basic protein

Little is known concerning the relative distribution and function of the different cyclic nucleotide phosphodiesterases (PDEs) in lymphocytes. Recent reports, however, have indicated that specific PDE4 inhibitors were effective in treatment of experimental allergic encephalomyelitis, an animal model of multiple sclerosis. The therapeutic effect of PDE4 inhibitors is thought to be related to inhibition of autoreactive CD4+ T cells specific for myelin basic protein (MBP) or other myelin proteins. Human autoreactive CD4+ T lymphocyte clones (TCC), specific for the immunodominant MBP epitope (amino acids 83-99), contain PDE3 and PDE4, two PDEs that exhibit a high affinity for cAMP. Amplification of TCC mRNA by reverse transcription-PCR indicated that TCC PDE3 mRNA was of the PDE3B, not PDE3A, subtype. Different TCC contained different proportions of PDE3 and PDE4, and their activities increased during Ag (MBP) stimulation. Specific PDE3 (cilostamide) and PDE4 (rolipram) inhibitors suppressed [3H]thymidine incorporation in TCC. Since it is believed that many autoimmune diseases are at least partially mediated by autoreactive CD4+ T cells, these observations may have important implications not only for the treatment of multiple sclerosis but also for other autoimmune diseases.

T cell response to myelin basic protein in the context of the multiple sclerosis-associated HLA-DR15 haplotype: peptide binding, immunodominance and effector functions of T cells

In this study, we evaluated the role of the two functional HLA-DR heterodimers, DR2a (DR alpha paired with the beta chain encoded by DRB5*0101) and DR2b (DR alpha paired with the beta chain encoded by DRB1*1501), that are coexpressed in the multiple sclerosis (MS)-associated haplotype HLA-DR15 Dw2, in presenting myelin basic protein (MBP) peptides to MBP-specific T cell lines (TCL). Our results show that both HLA-DR molecules serve as restriction elements for HLA-DR15-restricted TCL. Slightly higher numbers of TCL use DR2a as restriction element, and the epitopes contained in the immunodominant C-terminal region (131-159) are uniquely restricted by DR2a. The immunodominant middle epitope (81-99) is recognized in the context of both DR2a and DR2b, but this specificity strongly dominates the DR2b-restricted T cell response. Overall, immunodominance in the MBP-specific T cell response correlated well with peptide binding to DR2a or DR2b, demonstrating that the affinity of MHC-peptide interactions is important for shaping the T cell response to this autoantigen. Furthermore, we show that binding of the middle MBP peptide to HLA-DR15 molecules prevents cleavage by cathepsin D, a protease abundantly found in endosomal processing compartments, and thus contributes to its immunodominance. Surprisingly, the restriction element employed by MBP-specific T cell clones influenced the effector function (i.e., cytotoxic activity) of T cells irrespective of their peptide fine specificity.

Visual Motion Perception and Field Dependence

The aim of this research was to throw light on the relationship between the visual field dependence, as measured by a rod-and-frame test (RFT), and the amount of recorded postural sway subsequent to a visual motion of the environment. Two groups of fifteen adult participants were split according to their results in an RFT test. They were asked to maintain an upright stance within a large-scale scenery animated by a texture flow generator. The flow consisted of either an approaching (AP) or a receding (RE) texture with respect to the observer. An ELITE system recorded antero - posterior body sway after onset and offset of stimulus motion.

Both field-dependent (FD) and field-independent (FI) participants showed little reaction to AP whereas only FD participants presented a forward shift in the direction of RE at the onset. Postural responses opposite to AP and RE were marked for both groups at the offset. In conclusion we may assume an interaction between the direction specificity of the sways and a greater field dependence.

Differential expression of cyclic nucleotide phosphodiesterase 3 and 4 activities in human T cell clones specific for myelin basic protein

Little is known concerning the relative distribution and function of the different cyclic nucleotide phosphodiesterases (PDEs) in lymphocytes. Recent reports, however, have indicated that specific PDE4 inhibitors were effective in treatment of experimental allergic encephalomyelitis, an animal model of multiple sclerosis. The therapeutic effect of PDE4 inhibitors is thought to be related to inhibition of autoreactive CD4+ T cells specific for myelin basic protein (MBP) or other myelin proteins. Human autoreactive CD4+ T lymphocyte clones (TCC), specific for the immunodominant MBP epitope (amino acids 83-99), contain PDE3 and PDE4, two PDEs that exhibit a high affinity for cAMP. Amplification of TCC mRNA by reverse transcription-PCR indicated that TCC PDE3 mRNA was of the PDE3B, not PDE3A, subtype. Different TCC contained different proportions of PDE3 and PDE4, and their activities increased during Ag (MBP) stimulation. Specific PDE3 (cilostamide) and PDE4 (rolipram) inhibitors suppressed [3H]thymidine incorporation in TCC. Since it is believed that many autoimmune diseases are at least partially mediated by autoreactive CD4+ T cells, these observations may have important implications not only for the treatment of multiple sclerosis but also for other autoimmune diseases.

Interferon-beta interferes with the proliferation but not with the cytokine secretion of myelin basic protein-specific, T-helper type 1 lymphocytes

Interferon-beta (IFN-beta) has beneficial effects on the frequency and severity of relapses, as well as on disease progression in patients suffering from relapsing-remitting MS. Its mode of action, however, is not completely understood. Previous studies on T-lymphocyte bulk cultures and T-lymphocyte lines with specificity for different antigens suggested that the drug might partially act via suppression of T-cell proliferation and secretion of proinflammatory cytokines like interferon-gamma (IFN-gamma) and/or tumor necrosis factor-alpha (TNF-alpha). In this study we investigated the effects of human recombinant IFN-beta 1b on proliferation, interleukin 2 (IL-2) receptor (IL-2R) alpha-chain upregulation, and cytokine and chemokine secretion of myelin basic protein-reactive, MS patient-derived T-cell clones secreting T-helper type 1 (Th1) cytokines. IFN-beta partially suppressed both antigen- and IL-2-driven proliferation of these cells without affecting the expression of either IL-2 or IL-2R alpha-chain. There was no inhibitory effect on the secretion of IFN-gamma, TNF-alpha, and macrophage inflammatory protein (MIP)-1 alpha, but release was rather slightly enhanced. In conclusion, while IFN-beta does reduce proliferation of Th1-like, MBP-specific T cells in vitro, the drug does not result in overall dysfunction of these cells. Therefore, the effect of IFN-beta on MS may not depend on a primary inhibition of potentially encephalitogenic T lymphocytes.

Differential roles of neuroticism, extraversion, and event desirability for mood in daily life: an integrative model of top-down and bottom-up influences

Top-down and bottom-up approaches were combined to assess the relative impact of extraversion, neuroticism, and daily events on daily mood. Ninety-six community-residing men completed diaries for 8 consecutive nights. Extraversion predicted positive mood, whereas neuroticism predicted positive and negative mood. Undesirable events predicted negative mood and, more modestly, positive mood. Desirable events predicted positive mood. Negative dispositional and situational factors play a larger role in daily positive affect than positive factors do in daily negative affect.

Immunodominance of a low-affinity major histocompatibility complex-binding myelin basic protein epitope (residues 111-129) in HLA-DR4 (B1*0401) subjects is associated with a restricted T cell receptor repertoire

The pathogenesis of multiple sclerosis (MS) is currently ascribed in part to a T cell-mediated process targeting myelin components. The T cell response to one candidate autoantigen, myelin basic protein (MBP), in the context of HLA-DR15Dw2, has been previously studied in detail. However, the characteristics of cellular immunity in the context of other MS-associated HLA-DR haplotypes are scarcely known. MBP-specific T cell lines (TCL) were generated from HLA-DR4 (B1*0401)-positive MS subjects. Out of 275 MBP-specific TCL, 178 (64. 7%) specifically recognized region MBP(111-129), predominantly in the context of DRB1*0401. The major T cell epitope for MBP recognition corresponded to residues MBP(116-123). These TCL expressed disparate profiles of cytokine secretion and cytotoxicity. T cell receptor analysis, on the other hand, revealed a strikingly limited heterogeneity of rearrangements. In contrast to MBP(81-99), which binds with high affinity to HLA-DR15 and is recognized by a diverse T cell repertoire, MBP(111-129) binds weakly to DRB1*0401, suggesting that only high affinity T cell receptors might be able to efficiently engage such unstable MHC/peptide complexes, thus accounting for the T cell receptor restriction we observed. This study provides new insight about MBP recognition and proposes an alternative mechanism for immunodominance of self-antigen T cell epitopes in humans.

Controlling pattern formation and spatio-temporal disorder in nonlinear optics

We present a feedback control method for the stabiliza- tion of unstable patterns and for the control of spatio-temporal disor- der. The control takes the form of a spatial modulation to the input pump, which is obtained via filtering in Fourier space of the output electric field. The control is powerful, exible and non-invasive: the feedback vanishes once control is achieved. We demonstrate by means of computer simulation, the effect of the control in two different optical systems.