Gastro-oesophageal reflux disease: Medical or surgical treatment? Report of an interactive workshop

Gastroesophageal reflux disease (GERD) is the most common disease of the upper gastrointestinal tract. With the introduction of proton pump inhibitors medical treatment of GERD has been significantly improved. However, the development of laparoscopic antireflux surgery resulted in an increasing interest of surgeons in this disease. An interactive meeting was organized in order to develop an agreement between gastoenterologists and surgeons regarding therapeutic decisions and this is the main topic of this paper.     

Uroscopy in the 21st century: high-field NMR spectroscopy

From the experiments described, it can be seen that there are different research approaches that can be taken and these are summarized in Table 1. Whereas much scientific research is principally hypothesis led, there remains, nevertheless, an important place for exploratory research. High resolution NMR can measure, directly and simultaneously, a wide range of endogenous metabolites in biological fluids and has the unique capability of providing structural information on the metabolites detected. It has proved to be a powerful research tool with which to study inherited metabolic diseases, renal disease, drug metabolism, and toxicity, and can be used to monitor the effects of drug therapy. For instance, by using a library of experimental toxins one can map the metabolic profile of site-specific nephron injury. With this approach in man one could eventually take an unknown disease such as Balkan nephropathy and predict the initial site of tubular injury, the mode of injury and therefore the kind of toxin capable of producing that injury. NMR spectroscopic techniques are still advancing rapidly, with ever increasing sensitivity and sophistication of NMR pulse sequences to enhance structural elucidation in complex mixtures. Given the advances in directly coupled HPLC-NMR and even HPLC-NMR-mass spectroscopy it is likely that these technologies in conjunction with pattern recognition will make major contribution to our understanding of renal processes and provide new diagnostic insights in the 21st century.      

Beta-defensin genomic copy number is not a modifier locus for cystic fibrosis

Human beta-defensin 2 (DEFB4, also known as DEFB2 or hBD-2) is a salt-sensitive antimicrobial protein that is expressed in lung epithelia. Previous work has shown that it is encoded in a cluster of beta-defensin genes at 8p23.1, which varies in copy number between 2 and 12 in different individuals. We determined the copy number of this locus in 355 patients with cystic fibrosis (CF), and tested for correlation between beta-defensin cluster genomic copy number and lung disease associated with CF. No significant association was found.     

Missense FGFR3 mutations create cysteine residues in thanatophoric dwarfism type I (TD1)

Thanatophoric dwarfism (TD) is a sporadic lethal skeletal dysplasia with micromelic shortening of the limbs, macrocephaly, platyspondyly and reduced thoracic cavity. In the most common subtype (TD1), femurs are curved, while in TD2, straight femurs are associated with cloverleaf skull. Mutations in the fibroblast growth factor receptor 3 (FGFR3) gene were identified in both subtypes. While TD2 was accounted for by a single recurrent mutation in the tyrosine kinase 2 domain, TD1 resulted from either stop codon mutations or missense mutations in the extracellular domain of the gene. Here, we report the identification of FGFR3 mutations in 25/26 TD cases. Two novel missense mutations (Y373C and G370C) were detected in 8/26 and 1/26 TD1 cases respectively. Both mutations created cysteine residues in the juxta extramembrane domain of the receptor. Sixteen cases carried the previously reported R248C (9/26 cases), S249C (2/26 cases) or stop codon FGFR3 mutations (5/26 cases). Our results suggest that TD1 is a genetically homogeneous condition and give additional support to the view that newly created cysteine residues in the extracellular domain of the protein play a key role in the severity of the disease.      

Chloride distribution in Aplysia neurones

1. The intracellular Cl^- concentration (Cl_i) and the membrane potential (E_m) were measured in the medial pleural neurones of Aplysia under various experimental conditions designed to determine the Cl^- conductance of the neurones and investigate the possibility of an active Cl^- transport.

2. The magnitude of the Cl^- conductance of the cell depends on the experimental conditions.

3. In normal sea water, large changes of E_m produced by passing current across the cell membrane caused no change of Cl_i, suggesting that the Cl^- conductance was low. Similarly, moderate changes of E_Cl produced by decreasing Cl_o or increasing Cl_i had little or no effect on E_m.

4. A high Cl^- conductance was observed in high K_o or very low Cl_o. It was greatly reduced if the external Ca²⁺ was replaced by Co²⁺, or in the presence of tubocurarine, or if the experiment was performed on an isolated cell soma. The high Cl^- conductance is therefore attributed to the release of ACh and perhaps other transmitters from synaptic terminals.

5. High concentrations of tetraethylammonium ions or procaine induced a depolarization of the cell, but a decrease of Cl_i. The rate of fall of Cl_i was increased by lowering external K⁺ or raising external Ca²⁺, and was decreased by replacing external Ca²⁺ by Co²⁺.

6. NH₄⁺ ions applied externally had effects similar to those of K⁺ ions. In situations in which intracellular NH₄⁺ might be increased a fall in Cl_i was observed.

7. The changes of Cl_i caused by TEA, procaine, or internal NH₄⁺ occur against the driving force for passive Cl^- movements. They are still observed in isolated cell bodies, and cannot be attributed to the activation of synaptic channels.

8. Some interpretations of these anomalous Cl^- movements are discussed which could also account for the difference between E_Cl and E_m observed under normal conditions.

     

Glomerular thrombosis and cortical infarction in cyclosporin-treated rabbits with acute serum sickness.

Rabbits given acute serum sickness (ASS) and treated with cyclosporin A (CyA) developed glomerular capillary thrombosis and cortical infarction, lesions not seen in unmodified ASS. Thirty-three NZW rabbits received a single intravenous injection of 250 mg/kg bovine serum albumen (BSA) with or without endotoxin (5 micrograms/kg) on day 0. Groups of rabbits were given intramuscular CyA as follows: 15 mg/kg from day -2 to +8, or 25 mg/kg/day from day -20 to +3 or day 0 to 5. Signs of this renal injury were haematuria, transient proteinuria, glycosuria and oliguria and they occurred during the rapid phase of antigen elimination when immune complexes were being formed. Seventeen of the 33 rabbits developed glomerular capillary thrombi and 11 of 17 also had glomerular and tubular infarction. Electron microscopic examination showed that these lesions were associated with severe endothelial injury and platelet-fibrin-leucocyte thrombi. These changes were more severe in the groups given 25 mg/kg. The lesions were not seen in untreated rabbits and ASS, nor in normal rabbits given equivalent doses of CyA alone. A strikingly similar renal lesion has been seen in patients receiving CyA following bone marrow transplantation, and also in the haemolytic uraemic syndrome. The model we describe may be valuable for the study of the mechanisms of endothelial injury and thrombosis in the kidney.     

Processing and major histocompatibility complex class II presentation of Legionella pneumophila antigens by infected macrophages

To better understand interactions between the intracellular pathogen Legionella pneumophila and macrophages (Mphis), host and bacterial determinants important for presentation of antigens on major histocompatibility complex class II molecules (MHC-II) were investigated. It was determined that immune CD4 T-cell responses to murine bone marrow-derived Mphis (BMphis) infected with wild-type L. pneumophila were higher than the responses to avirulent dotA mutant bacteria. Although this enhanced response by immune T cells required modulation of vacuole transport mediated by the Dot/Icm system, it did not require intracellular replication of L. pneumophila. Intracellular cytokine staining identified a population of immune CD4 T cells that produced gamma interferon upon incubation with BMphis infected with wild-type L. pneumophila that did not respond to Mphi infection with dotA mutant bacteria. Endocytic processing was required for presentation of L. pneumophila antigens on MHC-II as determined by a defect in CD4 T-cell responses when the pH of BMphi endosomes was neutralized with chloroquine. Investigation of MHC-II presentation of antigens by BMphis infected with L. pneumophila icmR, icmW, and icmS mutants indicated that these mutants have an intermediate presentation phenotype relative to those of wild-type and dotA mutant bacteria. In addition, it was found that antigens from dot and icm mutants are presented earlier than antigens from wild-type L. pneumophila. Although immune CD4 T-cell responses to proteins secreted by the L. pneumophila Lsp system were not detected, it was found that the Lsp system is important for priming L. pneumophila-specific T cells in vivo. These data indicate that optimal antigen processing and MHC-II presentation to immune CD4 T cells involves synthesis of L. pneumophila proteins in an endoplasmic reticulum-derived compartment followed by transport to lysosomes.