Use of cardiac electric near-field measurements to determine activation times

In a recent paper, we described the behavior of the cardiac electric near-field, E, parallel to the tissue surface during continuous conduction. We found that T(E), the time at which the peak near-field, E, occurs, is an accurate marker of local activation time. Examination of experimentally recorded E vector loops revealed a large variety of morphologies. We postulated that propagation around an obstacle could lead to the observed deviations in loop morphology. The purpose of this study was to determine if this was plausible, and if so, whether T(E) remains an accurate time marker of local activation under these conditions. We used a monodomain computer model of a sheet of cardiac tissue with a central conduction obstacle immersed in an unbounded volume conductor. Activation times T(Im), T(phi), and T(E) were derived from the transmembrane current I(m), the extracellular potential phi(e), and E, respectively. The obstacle led to deformations of the vector loops, morphologically similar to those observed experimentally, particularly during the initial and terminal phases, and to a lesser degree near the time of E. Despite these loop deformations, T(E) was an accurate time marker of local activation. We found that T(E) was significantly closer to T(Im) than T(phi). We concluded that isochrone maps computed from T(E) better reflect intracellular activation patterns than those computed from T(phi). For a given electrode spacing of 60 microm, the sensitivity to noise of E was significantly less than that of phi(e). Hence, T(E) was less affected by noise than T(phi).

A novel cluster of lectin-like receptor genes expressed in monocytic, dendritic and endothelial cells maps close to the NK receptor genes in the human NK gene complex

The NK gene complex is a region on human chromosome 12 containing several families of lectin-like genes including the CD94 and NKG2 NK receptor genes. We report here that the region telomeric of CD94 contains in addition to the LOX-1 gene the novel human DECTIN-1 and the CLEC-1 and CLEC-2 genes within about 100 kb. Sequence similarities and chromosomal arrangement suggest that these genes form a separate subfamily of lectin-like genes within the NK gene complex. DECTIN-1 is selectively expressed in dendritic cells and to a lower extent in monocytes and macrophages. mRNA forms with and without a stalk exon are observed. During functional maturation of dendritic cells the level of DECTIN-1 mRNA is down-regulated several-fold. CLEC-1 is found to be not only expressed in dendritic cells, but also in endothelial cells and in the latter aspect resembles the LOX-1 gene. Whereas recombinant full-length DECTIN-1 and LOX-1 are transported to the cell surface, CLEC-1 proteins accumulate in perinuclear compartments. We propose that this family of lectin-like genes encodes receptors with important immune and/or scavenger functions in monocytic, dendritic and endothelial cells.

Bone marrow fibroblasts in patients with advanced lung cancer

In a previous study we demonstrated that the incidence of fibroblast colony-forming units (CFU-F) was very low in bone marrow primary cultures from the majority of untreated advanced non-small lung cancer patients (LCP) compared to normal controls (NC). For this reason, we studied the ability of bone marrow stromal cells to achieve confluence in primary cultures and their proliferative capacity following four continuous subcultures in consecutive untreated LCP and NC. We also evaluated the production of interleukin-1beta (IL-1beta) and prostaglandin E2 (PGE2) by pure fibroblasts. Bone marrow was obtained from 20 LCP and 20 NC. A CFU-F assay was used to investigate the proliferative and confluence capacity. Levels of IL-1beta and PGE2 in conditioned medium (CM) of pure fibroblast cultures were measured with an ELISA kit and RIA kit, respectively. Only fibroblasts from 6/13 (46%) LCP confluent primary cultures had the capacity to proliferate following four subcultures (NC = 100%). Levels of spontaneously released IL-1beta were below 10 pg/ml in the CM of LCP, while NC had a mean value of 1,217 +/- 74 pg/ml. In contrast, levels of PGE2 in these CM of LCP were higher (77.5 +/- 23.6 pg/ml) compared to NC (18.5 +/- 0.9 pg/ml). In conclusion, bone marrow fibroblasts from LCP presented a defective proliferative and confluence capacity, and this deficiency may be associated with the alteration of IL-1beta and PGE2 production.

An inhibitory role of the phosphatidylinositol 3-kinase-signaling pathway in vascular endothelial growth factor-induced tissue factor expression

Vascular endothelial growth factor (VEGF) is not only essential for vasculogenesis and angiogenesis but is also capable of inducing tissue factor, the prime initiator of coagulation, in endothelial cells. In this study we have analyzed the VEGF-elicited pathways involved in the induction of tissue factor in human umbilical cord vein endothelial cells. Using specific low molecular weight inhibitors we could demonstrate a crucial role of the p38 and Erk-1/2 mitogen-activated protein (MAP) kinases. In contrast, treatment with wortmannin or LY294002, inhibitors of phosphatidylinositol 3 (PI3)-kinase, resulted in a strong enhancement of the VEGF-induced tissue factor production, indicating a negative regulatory role of the PI3-kinase on tissue factor-inducing pathways. Accordingly, transduction with constitutively active Akt led to a reduction of VEGF-induced tissue factor production. Western blot analyses using antibodies specific for phosphorylated p38 showed an enhanced activation of this MAP kinase in human umbilical cord vein endothelial cells when stimulated with VEGF in the presence of wortmannin in comparison to either agent alone. Thus, the negative regulation of the PI3-kinase pathway on endothelial tissue factor activity can be explained at least in part by a suppression of this MAP kinase-signaling pathway. This is the first demonstration of a reciprocal relationship between procoagulant activity and the PI3-kinase-Akt signaling pathway, and it reveals a novel mechanism by which tissue factor expression can be controlled in endothelial cells.

["I am a Misunderstood Being on Earth" - Concept of illness of patients suffering from schizophrenic psychosis before and after psychoeducational treatment]

OBJECTIVE

To determine the effects of a psychoeducational intervention on the individual concepts of illness of patients suffering from schizophrenia.

METHOD

27 patients with a diagnosis of schizophrenia according to ICD-10 were interviewed with open ended questions about their concept of illness at admission to a day hospital and after 10 weeks of attending a psychoeducational program. Questions concerned terminology, diagnosis, prognosis, interventions and aetiology. A qualitative analysis of these data is presented.

RESULTS

The terms used to describe the illness were mostly colloquial. Highly individualized and heterogeneous concepts of illness, aetiology and helpful interventions and a positive view regarding prognosis prevailed. Changes over time were limited and arbitrary.

CONCLUSIONS

The concepts offered by professionals were adopted in a very limited way, which can be understood in the context of highly individualized ways of coping with diagnosis and illness.

[Identification of Vibrio spp bacteria on skin lesions of fisherman in the county of Raposa-MA]

The study was undertaken aiming at identifying bacteria from the county of Raposa in the state of Maranhão. The clinical sample was collected by using a swab and held in a Cary-Blair transport medium. Enrichment in alkaline peptone water, isolation in TCBS selective indicator medium and biochemical coding of species were used for laboratory processing. Fifty fisherman with age varying from 12-65 years took part on the study. Vibrio bacteria isolated in 21 subjects had been identified. There was a predominance of V. alginolyticus (66.6%) followed by V. parahaemolyticus (42.8%), and V. cholerae non-O1 (9.5%). Lesions predominated on lower limbs, presenting hyperhemia, swelling, secretion, and pain. Some species of gram-negative bacteria of the Serratia, Proteus, Escherichia, Citrobacter, Enterobacter associated to the vibrios were isolated, as well as other non-fermenting bacteria (30.9) and gram-positive bacteria of the genos Staphylococcus.

Impaired conditional discrimination learning in schizophrenia

Learning deficits have repeatedly been found in patients with schizophrenia. Eyelid conditional discrimination learning (ECDL) is a test of discriminative aversive conditioning and places minimal demands on motivation. An ECDL task was used to examine residual and paranoid type individuals with schizophrenia and age- and gender-equivalent healthy controls. In the experiment two differently colored light stimuli were randomly presented. Only one of the stimuli (in reinforced trials) was followed by an aversive airpuff to the cornea, as opposed to unreinforced trials where the stimulus was not followed by an aversive airpuff. Conditioned responses develop to both trial types during the course of the experiment. These conditioned responses consist of reflectory eyelid closures already upon light presentation. The patients showed significantly impaired conditional discrimination learning abilities. There was no significant difference between the results in the two schizophrenia subtypes. Patients failed to increase response frequencies on reinforced trials during the course of the experiment, while controls showed appropriate conditional discrimination ability. Thus the results show an impairment of adequate behavior modification in an aversive conditioning task in individuals with schizophrenia. It is concluded that ECDL might be a trait marker for schizophrenia.

The centromeric part of the human natural killer (NK) receptor complex: lectin-like receptor genes expressed in NK, dendritic and endothelial cells

The human natural killer (NK) receptor complex encompasses a region of about 2 Mb on the short arm of chromosome 12. It contains at least 18 lectin-like receptor genes, of which some are expressed in NK and NK/T cells and function as NK receptors. Close to the CD94 and NKG2 NK receptor genes in the centromeric part, a novel family of genes, expressed in myeloid, dendritic and/or endothelial cells, recently became evident. These genes encode a receptor for oxidized low density lipoprotein in endothelial cells and three other receptors potentially serving regulatory functions in dendritic cells. Although the overall structure of the human NK receptor complex is similar to the syntenic rodent regions, the centromeric part lacks the cluster of Ly49 genes. This supports the notion that recognition of MHC class Ia molecules has evolved separately in rodents and humans in the lectin-like Ly49 and the killer immunoglobulin-like receptors, respectively. In the telomeric part, other lectin-like genes expressed in different hematopoietic lineages are found. The receptors of the NK receptor complex apparently serve important functions in several leukocytes and in endothelial cells, and the exact role of these receptors, their ligands, and their distinct and co-ordinate regulation in different cell lineages warrants further investigation.

Model study of vector-loop morphology during electrical mapping of microscopic conduction in cardiac tissue

The large variety in loop morphology of potential differences recorded at the cardiac surface has been generally attributed to structural discontinuities of the tissue. The aim of this work was to examine if the diversity of vector loops of the electric field E found experimentally may also arise during continuous anisotrope conduction. For this purpose a monodomain computer model was used, consisting of a two-dimensional sheet of excitable tissue surrounded with an unbounded volume conductor. Close to the tissue surface our computations predicted a narrow biphasic course of phi(e) with peak-to-peak separation of less than 400 microm. We examined how accurately E could be reconstructed from measurements recorded with four-element electrode arrays and how activation sequence, interelectrode spacing, and probe orientation affects the results. We found "closed" vector loops of E in planar, and at the apex of elliptical wave fronts, whereas outside of these regions vector loops were "open." Varying probe orientation and size resulted in substantial changes of vector-loop morphology. We concluded that close to the cardiac current sources accurate measurement of E would require interelectrode distances of less than 100 microm.

The centromeric part of the human NK gene complex: linkage of LOX-1 and LY49L with the CD94/NKG2 region

The natural killer (NK) gene complex is a genomic region containing lectin-type receptor genes. We have established a contig of PAC and BAC clones comprising about 1 Mb of the centromeric part of the NK gene complex. This region extends from the LOX-1 gene, which encodes a receptor for oxidized LDL and was found within 100 kb telomeric of the STS marker D12S77, contains the CD94 and NKG2 NK receptor genes and reaches beyond D12S852 on the proximal side. In this part we have mapped the human LY49L gene, a homologue of the rodent Ly49 genes, which encode important MHC class I receptors for the regulation of NK cell activity in rodents. The LY49L gene is localized 100 to 200 kb centromeric of the NKG2 gene cluster and 300 to 400 kb telomeric of the STS marker D12S841. Genomic sequencing of the complete gene including promoter and intron sequences confirmed that the structure is similar to the mouse Ly49 genes. Screening of several cDNA libraries did not detect any transcripts of putative additional human LY49 genes. In addition, in the course of these studies several EST sequences were localized in the region, one immediately upstream of the LY49L gene.

Vibrio cholerae resistant to 2,4-diamino-6,7-diisopropylpteridine (O/129) isolated from patients with enteritis in Ceará, Brazil

This paper reports the characterization of clinical Vibrio cholerae resistant to vibriostatic agent O/129, using classical and plasmid analysis. In a study conducted during December 1991-September 1993, two of 7,058 V. cholerae strains, obtained from patients suspected to have cholera in the State of Ceará, northeast Brazil, were resistant to 150 micrograms of the vibriostatic agent O/129 (2,4-diamino-6,7-diisopropylpteridine). One strain was identified as V. cholerae O1 El Tor Inaba and the other one as serogroup O22. Only one O1 strain harboured a plasmid of 147 kb transferable to Escherichia coli K12, and five strains of V. cholerae O1 and non-O1 were sensitive to O/129 and plasmid-negative at a frequency between 8 x 10(-2) and 3.6 x 10(-5). Additionally, O/129-resistant strains of V. cholerae O1 and O22 were resistant to trimethoprim/sulphamethoxazole.

[High Resolution ECG Methods and Programmed Stimulation]

There are not many "gates to death", but one of the most important is the sudden cardiac death. Therefore the exact knowledge of drug effects on the cardiac function, especially of arhythmogenic side effects are crucial during the development of a new compound. Hitherto expensive catheter experiments in anesthetized animals (dogs, pigs or monkeys) were necessary to evaluate drug effects on the intracardiac electrophysiological activity of all parts of the cardiac conduction system. Only these intracardiac stimulation and recording methods were suitable to measure drug effects on all parameters used in clinical electrophysiology. A suitable method, to replace at least partly these catheter experiments, was developed with a new epicardiac surface and stimulation technique (SST-ECG method: Stark et al, Basic Res. Cardio. 82, 437, 1987; Stark et al, J. Pharmacol. Meth. 21, 195, 1989) which received the prize of the Austrian government for "Alternative Methods to Animal Experiment" in 1988. With this method all parameters used in clinical electrophysiology can be evaluated in one isolated heart preparation and, thus, interactions with anesthetics and of the vegetative nervous system can be excluded. Due to the high resolution of this system, the common ECG-Parameters (PQ-, QT-time and heart rate) and the low amplitude signals (such as early atrial and His-bundle signals) can be detected continuously. Additionally, the refractory periods of all parts of the conduction system can be determined. It is further possible to evaluate hemodynamic parameters such as left ventricular contraction amplitude and coronary flow. A great advantage of the SST-ECG method is the minor scattering of the values measured, due to the elimination of effects of anesthetics and of the vegetative nervous system and the lack of problems with the electrode position. In the future, the evaluation of drug effects on the cardiac electrical activity will further need laboratory animals, but the number of experiments can be significantly reduced and in vivo experiments on anesthetized dogs, pigs or monkeys can mainly be replaced by in vitro experiments using isolated heart preparations of rats or guinea-pigs.

Characterization and evaluation of some virulence markers of Listeria monocytogenes strains isolated from Brazilian cheeses using molecular, biochemical and serotyping techniques

A total of 207 L. monocytogenes strains isolated from different types of cheeses commercialized in the city of Rio de Janeiro, Brazil, were serotyped and evaluated for their ability to produce beta-haemolysin and lecithinase and to adsorb Congo red dye. Of the 207 strains, 59.9, 27.5 and 12.6% belonged to serotypes 1/2a, 1/2b and 4b, respectively. In addition, 175 strains of L. monocytogenes produced lecithinase while strains of the other species did not. Some of the non-L. monocytogenes strains adsorbed the dye Congo red, while some L. monocytogenes did not. Statistical analysis of the results showed significant differences (P < 0.05) amongst the virulence tests and the three serotypes found. In the present study, 32 L. monocytogenes strains were also analyzed by RAPD (randomly amplified polymorphic DNA). RAPD analysis allowed the discrimination among strains of different serotypes, as well as among strains of the same serotype. It is important to emphasize that the use of more than one primer is needed for characterization of L. monocytogenes strains. With RAPD the strains were grouped into six different profiles, some of them common for strains belonging to different serotypes. The results also indicated a close genetic relationship among strains of different serotypes.

Specificity, diversity, and convergence in VEGF and TNF-alpha signaling events leading to tissue factor up-regulation via EGR-1 in endothelial cells

Tissue factor (TF) has been shown to be up-regulated in endothelial cells by the inflammatory cytokine tumor necrosis factor alpha (TNF-alpha) as well as by the main angiogenic factor VEGF. Since both stimuli induce the transcription factor EGR-1, which is critically involved in TF gene regulation, we used EGR-1-dependent TF induction as a model to identify potential cross-talks between the various signal transduction cascades initiated by VEGF and TNF-alpha. The data show that at the MAP kinase level, VEGF mainly activates ERK1/2 and p38 MAP kinases in human endothelial cells. TNF-alpha is able to activate all three MAP kinase cascades as well as the classical inflammatory IkappaB/NFkappaB pathway. Furthermore, the MEK/ERK module of MAP kinases appears to act as the convergence point of VEGF- and TNF-alpha-initiated signaling cascades, which lead to the activation of EGR-1 and subsequent TF expression, whereas the upstream signals are distinct. We found that induction of TF by VEGF via EGR-1 is strongly PKC dependent. The TNF-alpha-initiated MEK/ERK cascade connected to EGR-1 and TF expression is clearly less sensitive to PKC inhibition. TNF-alpha-mediated activation of MEK/ERK and EGR-1 can be blocked by adenoviral expression of a dominant negative mutant of IKK2, whereas the VEGF signaling pathway is unaffected. Thus, our data demonstrate a new link between the classical inflammatory IKK/IkappaB and the MEK/ERK cascades triggered by TNF-alpha. The additional finding that EGF induces ERK and EGR-1 in a PKC-independent manner and that this signal is not sufficient to up-regulate TF emphasizes the importance of a VEGF-specific signaling pattern for the induction of TF.

The NKG2 natural killer cell receptor family: comparative analysis of promoter sequences

The NKG2 receptor family is crucially involved in target cell recognition by natural killer cells and comprises several activating as well as inhibitory family members. We have established approximately 3 kilobases of upstream promoter sequences of the human NKG2-C, -E and -F genes and have carried out a comparative analysis with available NKG2-A sequences. We found extended regions of homology which contain numerous putative transcription factor binding sites conserved in the NKG2 genes. However, variation in Alu insertion among family members has led to promoter structures unique to the respective family members, which could contribute to differences in transcriptional initiation as well as gene-specific regulation.

Species and serovars of the genus Listeria isolated from different sources in Brazil from 1971 to 1997

Using phenotype techniques, characterization was made to species and serovar of 3,112 strains of Listeria, isolated from different sources of infection such as human (247-7.9%) and animals (239-7.6%), as well as from various routes of infection, including food (2, 330-74.8%) and environmental constituents (296-9.5%), all coming from different regions of the country and collected during the period 1971-1997. The following species were recovered in the cultures analysed: L. monocytogenes (774-24.8%), L. innocua (2, 269-72.9%), L. seeligeri (37-1.1%), L. welshimeri (22-0.7%), L. grayi (9-0.2%), and L. ivanovii (1-0.03%). L. monocytogenes was represented by ten serovars, the most prevalent being 4b (352-11.3%), (1/2)a (162-5.2%), and (1/2)b (148-4.7%). The predominant serovar in L. innocua was 6a (2,093-67.2%). Considerations about laboratory methods for diagnosis and epidemiological aspects are presented on the basis of the results obtained.

Detection of Francisella tularensis in biological specimens using a capture enzyme-linked immunosorbent assay, an immunochromatographic handheld assay, and a PCR

The early detection of Francisella tularensis, the causative agent of tularemia, is important for adequate treatment by antibiotics and the outcome of the disease. Here we describe a new capture enzyme-linked immunosorbent assay (cELISA) based on monoclonal antibodies specific for lipopolysaccharide (LPS) of Francisella tularensis subsp. holarctica and Francisella tularensis subsp. tularensis. No cross-reactivity with Francisella tularensis subsp. novicida, Francisella philomiragia, and a panel of other possibly related bacteria, including Brucella spp., Yersinia spp., Escherichia coli, and Burkholderia spp., was observed. The detection limit of the assay was 10(3) to 10(4) bacteria/ml. This sensitivity was achieved by solubilization of the LPS prior to the cELISA. In addition, a novel immunochromatographic membrane-based handheld assay (HHA) and a PCR, targeting sequences of the 17-kDa protein (TUL4) gene of F. tularensis, were used in this study. Compared to the cELISA, the sensitivity of the HHA was about 100 times lower and that of the PCR was about 10 times higher. All three techniques were successfully applied to detect F. tularensis in tissue samples of European brown hares (Lepus europaeus). Whereas all infected samples were recognized by the cELISA, those with relatively low bacterial load were partially or not detected by PCR and HHA, probably due to inhibitors or lack of sensitivity. In conclusion, the HHA can be used as a very fast and simple approach to perform field diagnosis to obtain a first hint of an infection with F. tularensis, especially in emergent situations. In any suspect case, the diagnosis should be confirmed by more sensitive techniques, such as the cELISA and PCR.

Listeria monocytogenes in renal transplant recipients

Five cases of Listeria monocytogenes bacteremia were observed from April to December 1985, among renal transplant recipients from the same hospital in São Paulo, Brazil. The patients were adults (mean age: 40.6 years), and the basic complaint was fever, with no report of meningeal syndrome. Laboratory tests revealed the presence of two serovars, (1/2)a and 4b, which were classified into three lysotypes. The four strains of serovar 4b showed the same antibiotype, with resistance to cefoxitin, clindamycin, oxacillin and penicillin.

A new real-time mapping system to detect microscopic cardiac excitation patterns

A new fast, high-resolution measurement system has been developed to analyze the propagation of cardiac excitation on a microscopic scale. The instrument uses a microsensor array to detect microscopic excitation patterns at the cardiac surface. Ninety-six epicardial signals are recorded simultaneously with 14-bit resolution at 200-kHz samples per second per channel. The system operates like a digital oscilloscope. Preprocessing routines (offset, gain, and triggering) are executed within a sampling interval of 5 microseconds by 48 digital signal processors. Analog-to-digital (A/D) converters are provided with 12 Mb of buffer memory, allowing continuous recording of up to 64-k samples x 96 channels. The recorded dataset is transferred rapidly (8 Mb/sec) to the memory of the integrated computer system via VXIbus. Analysis and visualization of the propagating excitation are computed by custom-designed software. The performance of the system allows recording as well as visualization of the cardiac excitation spread in a beat-to-beat manner.

A transcriptional repressor of the tissue factor gene in endothelial cells

Tissue factor, the high-affinity receptor and cofactor for the plasma serine protease VII/VIIa, is the primary cellular initiator of the blood coagulation cascade. Inside the vasculature, expression of the tissue factor gene must be tightly controlled. Whereas the endothelium normally does not express tissue factor, on stimulation with inflammatory cytokines or endotoxin the gene is transcriptionally upregulated leading to a procoagulant state. We have now detected a repressive cis-acting element in the tissue factor promoter that downmodulates tissue factor transcription in endothelial cells. In reporter gene assays, deletion of this element leads to an increase of tissue factor transcription and insertion of a trimerized site reduces transcription. Specific protein/DNA complexes are formed on the element with nuclear extracts in electrophoretic mobility shift assays and cross-linking of the proteins followed by SDS-PAGE detects the presence of at least 2 subunits of approximately 40 and 60 kDa, respectively. After transfection of different cell types with the reporter genes, the suppressive effect of the element can only be revealed in endothelial cells. These data suggest that this element represents a novel transcription factor target sequence that functions to suppress expression of the tissue factor gene, preferentially in endothelial cells thereby supporting a noncoagulant state.

Vascular endothelial cell growth factor-induced tissue factor expression in endothelial cells is mediated by EGR-1

Vascular endothelial cell growth factor (VEGF) is a major regulator of angiogenesis. We report here that treatment of endothelial cells with VEGF leads to upregulation of tissue factor mRNA and protein expression on the cell surface. Reporter gene studies show that transcriptional activation of the tissue factor gene by VEGF is mediated by a GC-rich promoter element containing overlapping binding sites for Sp1 and EGR-1. As shown by immunofluorescence and electrophoretic mobility shift assays, upon VEGF treatment EGR-1 rapidly accumulates in the nucleus and binds to its respective recognition site in the tissue factor promoter. Sp1 occupies this element in unstimulated cells and seems to be partially displaced by increasing amounts of EGR-1. Transfection of endothelial cells with an EGR-1 expression plasmid mimics the upregulation of tissue factor transcription observed after VEGF treatment. In contrast, NFkappaB, the major transcription factor involved in tissue factor upregulation by inflammatory stimuli, is not activated by VEGF. These data show that VEGF induces a response in endothelial cells largely distinct from inflammatory stimuli, and suggest that EGR-1 is a major mediator of the activation of the tissue factor and possibly other VEGF-responsive genes.