Dopamine inhibits prostaglandin F2α-induced depolarization of rabbit jejunal arteries via activation of DA1-receptors

Summary In rabbit jejunal arteries, the membrane potential of single smooth muscle cells decreased on the application of noradrenaline 3 mol/1. LY 171555 1 mol/1 did not change, whereas SKF 38393 10 mol/1 reversed the effect of noradrenaline. When prostaglandin F₂ (PGF₂) was used to evoke depolarization in the presence of prazosin 0.1 mol/1, rauwolscine 1 mol/1 and propranolol 1 mol/1, both SKF 38393 10 mol/1 and dopamine 10 mol/1 repolarized the membrane. SCH 23390 1 mol/1 antagonized the effects of SKF 38393 10 mol/1 and dopamine 10 mol/1. Thus, the change in membrane potential is mediated by a DA₁-recep-tor.     

Functional analysis of the cag pathogenicity island in Helicobacter pylori isolates from patients with gastritis, peptic ulcer, and gastric cancer

Helicobacter pylori is the causative agent of a variety of gastric diseases, but the clinical relevance of bacterial virulence factors is still controversial. Virulent strains carrying the cag pathogenicity island (cagPAI) are thought to be key players in disease development. Here, we have compared cagPAI-dependent in vitro responses in H. pylori isolates obtained from 75 patients with gastritis, peptic ulcer, and gastric cancer (n = 25 in each group). AGS gastric epithelial cells were infected with each strain and assayed for (i) CagA expression, (ii) translocation and tyrosine phosphorylation of CagA, (iii) c-Src inactivation, (iv) cortactin dephosphorylation, (v) induction of actin cytoskeletal rearrangements associated with cell elongation, (vi) induction of cellular motility, and (vii) secretion of interleukin-8. Interestingly, we found high but similar prevalences of all of these cagPAI-dependent host cell responses (ranging from 56 to 80%) among the various groups of patients. This study revealed CagA proteins with unique features, CagA subspecies of various sizes, and new functional properties for the phenotypic outcomes. We further showed that induction of AGS cell motility and elongation are two independent processes. Our data corroborate epidemiological studies, which indicate a significant association of cagPAI presence and functionality with histopathological findings in gastritis, peptic ulcer, and gastric cancer patients, thus emphasizing the importance of the cagPAI for the pathogenicity of H. pylori. Nevertheless, we found no significant association of the specific H. pylori-induced responses with any particular patient group. This may indicate that the determination of disease development is highly complex and involves multiple bacterial and/or host factors.     

Rescue of lethal molybdenum cofactor deficiency by a biosynthetic precursor from Escherichia coli

Substitution therapies for orphan genetic diseases, including enzyme replacement methods, are frequently hampered by the limited availability of the required therapeutic substance. We describe the isolation of a pterin intermediate from bacteria that was successfully used for the therapy of a hitherto incurable and lethal disease. Molybdenum cofactor (Moco) deficiency is a pleiotropic genetic disorder characterized by the loss of the molybdenum-dependent enzymes sulphite oxidase, xanthine oxidoreductase and aldehyde oxidase due to mutations in Moco biosynthesis genes. An intermediate of this pathway-'precursor Z'-is more stable than the cofactor itself and has an identical structure in all phyla. Thus, it was overproduced in the bacterium Escherichia coli, purified and used to inject precursor Z-deficient knockout mice that display a phenotype which resembles that of the human deficiency state. Precursor Z-substituted mice reach adulthood and fertility. Biochemical analyses further suggest that the described treatment can lead to the alleviation of most symptoms associated with human Moco deficiency.     

Immunohistochemical detection of VEGF in the bone marrow of patients with acute myeloid leukemia. Correlation between VEGF expression and the FAB category

We studied vascular endothelial growth factor (VEGF) expression in bone marrow sections obtained from 3 healthy donors and 41 patients with acute myeloid leukemia (AML) of various French-American-British (FAB) subtypes by immunohistochemical analysis using an anti-VEGF antibody. In normal bone marrow, the anti-VEGF antibody reacted with myeloid progenitor cells and megakaryocytes but not with erythroid cells or mature granulocytic cells. High levels of VEGF were found in the bone marrow in patients with AML-M1, -M2, -M3, -M4, -M4Eo, and -M5. In these leukemias, the vast majority of myeloblasts (> 90%) expressed VEGF. By contrast, in AML-M0, the percentage of VEGF-positive blasts was lower in most cases (median, 42%), and if at all detectable, these blast cells contained only trace amounts of VEGF. In AML-M3 and -M4Eo, maturing granulocytes failed to express VEGF similar to granulocytes in normal bone marrow. In AML-M6, myeloblasts exhibited VEGF, whereas erythroid cells did not. In AML-M7, blast cells and megakaryocytes were identified as major sources of VEGF. In summary, VEGF expression in the bone marrow is restricted to certain stages of differentiation and maturation of myeloid cells and correlates with the FAB category.     

Effect of depressive symptoms on survival after heart transplantation

OBJECTIVE: This study explored the value of preoperative self-reported assessment for depression and anxiety in patients who had undergone heart transplantation (HTx). The initial sample was divided into subgroups of patients with ischemic (ICMP) and dilated cardiomyopathy (DCMP). Patient depression and anxiety scores were measured in both subgroups and their impact on pre- and postoperative mortality investigated. METHOD: An initial sample of 152 patients with either ICMP (N = 57) or DCMP (N = 95) and end-stage heart disease awaiting heart transplantation were assessed in a multidimensional longitudinal study, including psychological and somatic variables. One hundred and three patients received a HTx and were followed up for a mean of 4.4 years. Proportional hazard models were computed to test for the influence of psychosocial and somatic factors on outcome. RESULTS: Preoperative depression and state anxiety scores were significantly higher in the ICMP group. In addition to donor and recipient age, ICMP patients in the preoperative high depression group also showed a significantly higher mortality after HTx. This result remained significant even after controlling for sociodemographic and somatic variables. CONCLUSIONS: Patient self-reported depression, but not anxiety, can contribute to the identification of subgroups of patients with an unfavorable outcome after HTx. It therefore may be helpful to screen for depression, particularly in patients with an ischemic cause of their end-stage heart disease. Specific intervention programs should be further developed and evaluated.     

Decreased prefrontal 5-HT2A receptor binding in subjects at enhanced risk for schizophrenia

The brain serotonin-2A receptor (5-HT_2AR) has been implicated in both the pathology of schizophrenia and the therapeutic action of atypical antipsychotics. However, little is known about the 5-HT_2AR status before the onset of schizophrenia and before the exposure to antipsychotics. We used [¹⁸F] altanserin and positron emission tomography (PET) in a pilot study of 6 individuals suspected to be at elevated risk for schizophrenia and seven age-matched controls to test the hypothesis that regional 5-HT_2AR binding is altered in the prodromal stages of schizophrenia. Distribution volume ratios (DVRs) as a proxy for 5-HT_2AR availability were significantly reduced in prefrontal cortex regions of at-risk subjects, implicating early abnormalities of serotonergic neurotransmission that antecede the onset of schizophrenia.     

Interaction of PSD-95 with potassium channels visualized by fluorescence lifetime-based resonance energy transfer imaging

Resonance energy transfer (RET) has been extensively used to estimate the distance between two different fluorophores. This study demonstrates how protein-protein interactions can be visualized and quantified in living cells by time-correlated single-photon counting (TCSPC) imaging techniques that exploit the RET between appropriate fluorescent labels. We used this method to investigate the association of the potassium inward rectifier channel Kir2.1 and the neuronal PDZ protein PSD-95, which has been implicated in subcellular targeting and clustering of ion channels. Our data show that the two proteins not only colocalize within clusters but also interact with each other. Moreover, the data allow a spatially resolved quantification of this protein-protein interaction with respect to the relative number and the proximity between interacting molecules. Depending on the subcellular localization, a fraction of 20 to 60% of PSD-95 molecules interacted with Kir2.1 channels, approximating their fluorescent labels by less than 5 nm.     

Antigen discovery and delivery of subunit vaccines by nonliving bacterial ghost vectors

The bacterial ghost (BG) platform system is a novel vaccine delivery system endowed with intrinsic adjuvant properties. BGs are nonliving Gram-negative bacterial cell envelopes which are devoid of their cytoplasmic contents, yet maintain their cellular morphology and antigenic structures, including bioadhesive properties. The main advantages of BGs as carriers of subunit vaccines include their ability to stimulate a high immune response and to target the carrier itself to primary antigen-presenting cells. The intrinsic adjuvant properties of BGs enhance the immune response to target antigens, including T-cell activation and mucosal immunity. Since native and foreign antigens can be carried in the envelope complex of BGs, combination vaccines with multiple antigens of diverse origin can be presented to the immune system simultaneously. Beside the capacity of BGs to function as carriers of protein antigens, they also have a high loading capacity for DNA. Thus, loading BGs with recombinant DNA takes advantage of the excellent bioavailability for DNA-based vaccines and the high expression rates of the DNA-encoded antigens in target cell types such as macrophages and dendritic cells. There are many spaces within BGs including the inner and outer membranes, the periplasmic space and the internal lumen which can carry antigens, DNA or mediators of the immune response. All can be used for subunit antigen to design new vaccine candidates with particle presentation technology. In addition, the fact that BGs can also carry piggyback large-size foreign antigen particles, increases the technologic usefulness of BGs as combination vaccines against viral and bacterial pathogens. Furthermore, the BG antigen carriers can be stored as freeze-dried preparations at room temperature for extended periods without loss of efficacy. The potency, safety and relatively low production cost of BGs offer a significant technical advantage over currently utilized vaccine technologies.     

Urothelial carcinoma of the upper urinary tract: inverted growth pattern is predictive of microsatellite instability

Urothelial carcinoma of the renal pelvis and ureter may develop as a manifestation of hereditary nonpolyposis colorectal cancer syndrome (HNPCC), a disorder characterized by mutation or inactivation of a number of DNA mismatch repair genes and detectable as microsatellite instability (MSI). Some urothelial carcinomas display areas of endophytic, or inverted, growth. In this study, urothelial cancers of the upper urinary tract (n = 132) from patients treated at 2 tertiary care centers were studied to identify an association between growth pattern and MSI. Thirty-five neoplasms were microsatellite unstable (26.5%), and MSI was more frequent in papillary lesions than in sessile urothelial cancers (P = .033). The amount of inverted growth was estimated as a percentage of the total tumor. The interobserver and intraobserver concordance in recognizing inverted growth was good, and 65.7% of microsatellite-unstable tumors exhibited at least 20% of an inverted growth component, compared with only 17.5% of microsatellite-stable tumors (P < .0001). In this series, inverted growth predicted MSI with a sensitivity and specificity of .82. Inverted growth in urothelial carcinomas of the upper urinary tract may serve as a marker lesion for MSI and may help identify patients who should be offered testing for HNPCC.