Genetic ablation of carbonic anhydrase IX disrupts gastric barrier function via claudin‐18 downregulation and acid backflux

Aim

This study aimed to explore the molecular mechanisms for the parietal cell loss and fundic hyperplasia observed in gastric mucosa of mice lacking the carbonic anhydrase 9 (CAIX).

Methods

We assessed the ability of CAIX‐knockout and WT gastric surface epithelial cells to withstand a luminal acid load by measuring the pH_i of exteriorized gastric mucosa in vivo using two‐photon confocal laser scanning microscopy. Cytokines and claudin‐18A2 expression was analysed by RT‐PCR.

Results

CAIX‐knockout gastric surface epithelial cells showed significantly faster pH_i decline after luminal acid load compared to WT. Increased gastric mucosal IL‐1β and iNOS, but decreased claudin‐18A2 expression (which confer acid resistance) was observed shortly after weaning, prior to the loss of parietal and chief cells. At birth, neither inflammatory cytokines nor claudin‐18 expression were altered between CAIX and WT gastric mucosa. The gradual loss of acid secretory capacity was paralleled by an increase in serum gastrin, IL‐11 and foveolar hyperplasia. Mild chronic proton pump inhibition from the time of weaning did not prevent the claudin‐18 decrease nor the increase in inflammatory markers at 1 month of age, except for IL‐1β. However, the treatment reduced the parietal cell loss in CAIX‐KO mice in the subsequent months.

Conclusions

We propose that CAIX converts protons that either backflux or are extruded from the cells rapidly to CO₂ and H₂O, contributing to tight junction protection and gastric epithelial pH_i regulation. Lack of CAIX results in persistent acid backflux via claudin‐18 downregulation, causing loss of parietal cells, hypergastrinaemia and foveolar hyperplasia.     

Inhibition of malignant glioma cell growth by a survivin mutant retrovirus

Glioblastoma multiforme (GBM) is a highly malignant brain tumor that is resistant to conventional radiotherapy and chemotherapy. The median survival time of patients with GBM has remained less than 2 years despite concerted efforts to improve therapy. As a new approach to treat GBM we generated retroviral particles encoding mutant survivin for transduction of glioma cells. We demonstrate here that retroviral overexpression of a nonphosphorylatable Thr-34 --> Ala mutant of survivin (survivinT34A), in the glioma cell lines U373 and H4 resulted in a marked increase in the percentage of cells bearing multiple nuclei, which was accompanied by significantly decreased cell proliferation, and in greater numbers of cells with hypodiploid DNA content. Administration of the broad caspase inhibitor z-Val-Ala-Asp(OMe)-fluoromethyl-ketone did not reduce the cell death rate. Yet increased nuclear translocation of apoptosis-inducing factor (AIF) was observed in cells transduced with survivinT34A, indicating caspase-independent cell death. Transduction of retroviral vectors encoding wild-type survivin also led to the appearance of multinuclear cells. In contrast to mutant survivin, overexpressed wild-type survivin did not increase the cell death rate and no enhanced nuclear AIF translocation was observed. We suggest that retroviral vectors delivering mutant survivinT34A might be employed for the treatment of glioblastoma.     

La nécrosectomie transgastrique

La nécrosectomie transgastrique semble être une alternative présentant peu de risques de traitement pour les patients gravement atteints. Cependant, il manque à ce jour, une analyse des risques du procédé sur un nombre suffisant de patients; il est urgent de procéder à des collectes de données multicentriques. Il s’agit de procédés endoscopiques complexes, qui nécessitent une grande expérience, et le traitement de chaque patient devrait être planifié de fa?on interdisciplinaire en collaboration avec le chirurgien. Ce procédé devrait par conséquent rester limité aux centres spécialisés.     

Tissue plasminogen activator (tPA) as therapy for hepatotoxicity following bone marrow transplantation

The treatment of established veno-occlusive disease (VOD) of the liver with tissue plasminogen activator (tPA) has been disappointing. In attempts to improve upon these results we identified a subgroup of patients with consistently elevated bilirubin levels who did not meet conventional criteria for VOD (Susp VOD) but who had a significant risk of later developing clinical VOD. In January 1994 we began to treat patients who developed Susp VOD with tPA rather than waiting until they developed clinical VOD. We now report on the results of the first 37 patients who ultimately developed clinical VOD and received tPA therapy prior to Susp VOD, or at the time they had established VOD. Significant bleeding complications occurred in 13 (35%) patients but resolved with discontinuation of therapy in all but one. We found that patients treated early in the course of hepatotoxicity prior to the development of overt VOD had a significantly higher response rate and 100 day survival than patients treated at the time of established VOD. Given the poor results seen in treating late VOD, we suggest that early treatment with tPA may improve the outcome in patients who develop signs of hepatotoxicity following marrow transplantation.     

Transcranial Duplex Sonography and CT Angiography in Acute Stroke Patients

Acute occlusion of cervical or intracranial arteries is the most common cause of ischemic stroke (IS). The aims of the current study were to compare the occurrence of acute pathologic findings in intracranial arteries using transcranial color‐coded sonography (TCCS) and computed tomographic angiography (CTA) performed within 3 hours of IS onset and to assess the correlation between the vascular findings on admission and the patient's clinical state on admission and 3 months after the IS. Forty‐five consecutive patients with an acute IS were included in the prospective study during an 18‐month period. All patients underwent CTA and TCCS within the first 3 hours of symptom onset. A high rate of pathologic findings in the intracranial circulation was found (70.9% in CTA and 77.4% in TCCS examinations). The CTA and TCCS findings with respect to the intracranial arteries were consistent in 87.1% of cases (Cohen's κ, .797). The sensitivity, specificity, and positive and negative predictive values achieved with TCCS in patients with middle cerebral artery main stem occlusion were 92.3%, 94.4%, and 92.3% and 94.4%, respectively. There was no correlation between the patient's clinical status on admission and 3 months after the onset of the IS and the CTA or the TCCS findings (P > .1 in all cases). A substantial agreement was found between TCCS and CTA in the detection of pathologic findings in intracranial vessels in acute stroke patients. Both methods can be used for this purpose.     

The novel nomogram of Gleason sum upgrade: Possible application for the eligible criteria of low dose rate brachytherapy

Objective: To examine the rate of Gleason sum upgrading (GSU) from a sum of 6 to a Gleason sum of ≥7 in patients undergoing radical prostatectomy (RP), who fulfilled the recommendations for low dose rate brachytherapy (Gleason sum 6, prostate‐specific antigen ≤10 ng/mL, clinical stage ≤T2a and prostate volume ≤50 mL), and to test the performance of an existing nomogram for prediction of GSU in this specific cohort of patients. Methods: The analysis focused on 414 patients, who fulfilled the European Society for Therapeutic Radiation and Oncology and American Brachytherapy Society criteria for low dose rate brachytherapy (LD‐BT) and underwent a 10‐core prostate biopsy followed by RP. The rate of GSU was tabulated and the ability of available clinical and pathological parameters for predicting GSU was tested. Finally, the performance of an existing GSU nomogram was explored. Results: The overall rate of GSU was 35.5%. When applied to LD‐BT candidates, the existing nomogram was 65.8% accurate versus 70.8% for the new nomogram. In decision curve analysis tests, the new nomogram fared substantially better than the assumption that no patient is upgraded and better than the existing nomogram. Conclusions: GSU represents an important issue in LD‐BT candidates. The new nomogram might improve patient selection for LD‐BT and cancer control outcome by excluding patients with an elevated probability of GSU.     

Spider-venom peptides as bioinsecticides

Over 10,000 arthropod species are currently considered to be pest organisms. They are estimated to contribute to the destruction of ~14% of the world's annual crop production and transmit many pathogens. Presently, arthropod pests of agricultural and health significance are controlled predominantly through the use of chemical insecticides. Unfortunately, the widespread use of these agrochemicals has resulted in genetic selection pressure that has led to the development of insecticide-resistant arthropods, as well as concerns over human health and the environment. Bioinsecticides represent a new generation of insecticides that utilise organisms or their derivatives (e.g., transgenic plants, recombinant baculoviruses, toxin-fusion proteins and peptidomimetics) and show promise as environmentally-friendly alternatives to conventional agrochemicals. Spider-venom peptides are now being investigated as potential sources of bioinsecticides. With an estimated 100,000 species, spiders are one of the most successful arthropod predators. Their venom has proven to be a rich source of hyperstable insecticidal mini-proteins that cause insect paralysis or lethality through the modulation of ion channels, receptors and enzymes. Many newly characterized insecticidal spider toxins target novel sites in insects. Here we review the structure and pharmacology of these toxins and discuss the potential of this vast peptide library for the discovery of novel bioinsecticides.     

Occurrence of diabetes mellitus in spontaneous intracerebral hemorrhage

The role of diabetes mellitus (DM) in the etiopathogenesis of spontaneous intracerebral hemorrhage (SICH) is controversial. The aim was to assess the role of DM in our SICH patients. In a hospital-based cross-section study, the occurrence of DM prior to a hemorrhagic stroke was observed in 80 SICH patients (44 males, aged 36–87 years, mean 67.1 ± 11.9 years; 36 females, aged 56–86 years, mean 71.1 ± 8.3 years), and in a control group (CG) of 80 age- and sex-matched patients with low back pain. All patients were treated at the Departments of Neurology and Neurosurgery, University Hospital, Olomouc, Czech Republic. Two-sample t test and Pearson’s homogeneity χ² test were applied when assessing statistical significance. DM was found in 37.5% of SICH patients versus 22.5% of CG subjects (P < 0.05). DM occurs significantly more frequently in SICH patients in the Olomouc region of the Czech Republic when compared to the general population. The paper was presented in part as a poster at the 7th Congress of the European Federation of Neurological Societies in Helsinki, Finland in September 2003, and as a lecture at the XXXII^nd Czech-Slovak Neurovascular Symposium in Zlín, Czech Republic in June 2004.     

Diazepam binding inhibitor overexpression in mice causes hydrocephalus, decreases plasticity in excitatory synapses and impairs hippocampus-dependent learning

Diazepam binding inhibitor (DBI) and its processing products are endogenous modulators of GABAA and linked to various brain disorders ranging from anxiety and drug dependence to epilepsy. To investigate the physiological role of endogenously expressed DBI in the brain we created a transgenic mouse line overexpressing DBI gene. Transgenic mice had a 37x increased protein expression and immunohistochemistry showed excessive glial expression in the infragranular region of the dentate gyrus. Transgenic animals had significantly larger lateral ventricles and decreased plasticity of excitatory synapses without affecting either inhibitory or excitatory synaptic transmission. In behavioral tests transgenic animals had no differences in motor and exploratory activity, yet impaired hippocampus-dependent learning and memory. Overexpression did not cause anxiety or proconflict behavior, nor influenced kainic acid or pentylenetetrazole induced seizure activity. Our transgenic mouse line demonstrates that endogenously overexpressed DBI impairs hippocampus-dependent learning without anxiety or proconflict behavior.