Effect of the carbonic anhydrase inhibitor, acetazolamide, on Helicobacter pylori infection in vivo: a pilot study

BACKGROUND: Carbonic anhydrase inhibitors have been successfully used to treat peptic ulcers. Although carbonic anhydrase restriction does not inhibit Helicobacter pylori in vitro, recent studies suggest that carbonic anhydrase inhibition reduces the ability of H. pylori to survive in an acid environment as present in the stomach. METHODS: In a pilot study, we examined the effect of acetazolamide 500 mg as twice a day for 4 days in volunteers with active H. pylori infection. Effectiveness was judged by changes in the results of the urea breath test. RESULTS: Eight H. pylori infected volunteers completed the test. No urea breath test reverted to negative and there was a trend for the urea breath test value to increase [e.g. delta over baseline (DOB) mean +/- SE increased from 50.9 +/- 13 at baseline to 64.9 +/- 13 at day 5] during treatment with acetazolamide. CONCLUSION: The potential effect of carbonic anhydrase inhibitors on acid secretion may prevent effect on H. pylori in vivo and/or the sites of infection at the surface of the stomach may have a pH higher for any postulated acid-dependent effect to have an effect clinically.     

Urea Breath Test in Children: The United States Prospective, Multicenter Study

Background: The urea breath test (UBT) is generally considered the gold standard for the diagnosis of Helicobacter pylori infections in adults.
Goals: To investigate the utility and accuracy of urea breath testing in children from the United States.
Methods: Children scheduled to undergo upper gastrointestinal endoscopy for various clinical symptoms underwent a ¹³C-UBT using the US standard protocol for adults. Results were compared with rapid urease testing (RUT), culture, and histology. H. pylori positivity was defined according to the FDA, Division of Anti-Infective Drug Products criteria, i.e. positive culture and/or positive RUT and histology. H. pylori negativity was defined as all tests negative. Results were evaluated by delta over baseline (DOB) and urea hydrolysis rate (UHR).
Results: A total of 176 children from five centers were evaluated; 48 were infected. Compared to the defined standard, the results with the UBT based on delta over baseline (DOB) cut-off value (positive: ≥ 2.4‰) showed that the sensitivity and specificity of the UBT were 97.9% and 96.1%, respectively. Based on the UHR cut-off value (positive: ≥ 10.0 µg/min), the sensitivity and specificity were 95.8% and 99.2%. In young children (2- to 5-year olds), sensitivity and specificity of UHR method were higher than the DOB method (100% and 100% vs 100% and 82.4%, respectively).
Conclusion: The US standard ¹³C-UBT proved to be both simple and accurate for the diagnosis of H. pylori infections in children. The UHR method to calculate of ¹³C-UBT result provided excellent results for children of all ages.     

Extensive nerve overgrowth and paucity of the tailed asymmetric form (16 S) of acetylcholinesterase in the developing skeletal neuromuscular system of the dysgenic (mdg/mdg) mouse

Segmentation of the mesoderm in the head of a newt embryo is revealed by scanning electron microscopy. By the end of gastrulation, the newt embryo is already segmented from one end to the other, with additional segments added later by the tail bud. This metameric segmentation appears long before the first “somite” can be seen in the late neurula by light microscopy. The six segments found in the newt head look much like the six most-cranial segments described decades ago in shark embryos. Mesodermal segments in the newt head are similar to somitomeres in amniote embryos, but in amniote embryos, the numbers and relationships of head segments are quite different from those of the newt. In both amniote and newt, the first segment abuts the prosencephalon, but for each more caudal head segment, where the newt embryo has one segment, the amniote has two. Although the pattern and distribution of cranial neural crest is quite similar in newt and amniote embryos, there are different relationships between migrating crest masses and mesodermal segments due to the doubling of most of the cranial segments in amniotes. It now appears that all vertebrate embryos, regardless of their mode of gastrulation, form similar mesodermal segments from one end of the embryo to the other, and this metameric pattern is established during gastrulation.     

Plant-parasitic nematodes associated with organic and conventional vegetable farms in Laguna Province,Philippines

A survey was conducted to determine the prevalence of plant-parasitic nematodes associated with vegetable crops grown in organic and conventional farms in Laguna province, Philippines. Seven nematode genera (Aphelenchoides, Aphelenchus, Helicotylenchus, Meloidogyne, Pratylenchus, Rotylenchulus and Tylenchus) from organic farms and five (all those found in organic except Aphelenchoides and Pratylenchus) from conventional farms were isolated using modified Baermann tray method. Among these taxa, Meloidogyne and Rotylenchulus were the most prevalent and abundant in both organic and conventional farms. Pratylenchus was also prevalent in organic farms and Helicotylenchus in conventional farms. Rotylenchulus was found associated with every vegetable in both organic and conventional farms and Meloidogyne was also observed with all vegetables in conventional farms. Organic vegetable farms were more diverse in terms of genera of plant-parasitic nematodes than conventional farms.     

Effects of sirolimus on plasma lipids,lipoprotein levels,and fatty acid metabolism in renal transplant patients

Sirolimus (Rapammune, rapamycin, RAPA) is a potent immunosuppressive drug that reduces renal transplant rejection. Hyperlipidemia is a significant side effect of sirolimus treatment, and frequently leads to cardiovascular disease. This study was undertaken to determine the repeatability, reversibility, and dose dependence of the plasma lipid and apolipoprotein altering effects of sirolimus, and to elucidate the mechanism by which sirolimus induces hypertriglyceridemia in some renal transplant patients. Six patients with renal allografts maintained on cyclosporine A and prednisone were selected on the basis of their previous hyperlipidemic response to short term (14 days) sirolimus administration. For longer-term treatment, each patient was started on 10 mg/day sirolimus and continued as tolerated for 42 days to reinduce hyperlipidemia. Timed blood samples were analyzed for lipid, apolipoprotein, and sirolimus levels. During sirolimus administration, mean total plasma cholesterol increased from 214 mg/dl to 322 mg/dl (+50%; range 25-92%); LDL-cholesterol levels followed a similar pattern. Mean triglyceride level rose from 227 to 432 mg/dl (+95%; range 9-254%). ApoB-100 concentration rose from 124 to 160 mg/dl (+28%; P < 0.05). ApoC-III level increased from 28.9 to 55.5 mg/dl, +92%; (P < 0.013). These lipid and apolipoprotein changes were found to be repeatable, reversible, and dose dependent. [(13)C(4)]palmitate metabolic studies in four patients with hypertriglyceridemia indicated that the free fatty acid pool was expanded by sirolimus treatment (mean = 42.3%). Incorporation of [(13)C(4)]palmitate into triglycerides of VLDL, IDL, and LDL was decreased 38.3%, 42,1%, and 38.4%, respectively, by sirolimus treatment of these patients. These results suggest that sirolimus alters the insulin signaling pathway so as to increase adipose tissue lipase activity and/or decrease lipoprotein lipase activity, resulting in increased hepatic synthesis of triglyceride, increased secretion of VLDL, and increased hypertriglyceridemia.     

Molecular cloning and DNA homology of plasmid-mediated beta-lactamase genes

Summary Molecular cloning of DNA fragments between 1.5 and 8kb from BamHI, EcoRI, HindIII, SalI, or Sau3A digests permitted the isolation of structural genes coding for TEM-1, ROB-1, OXA-1, OXA-3, OXA-4, OXA-5, PSE-1, PSE-2, PSE-3, PSE-4, CARB-3, CARB-4, AER-1, and LCR-1 -lactamases. Ampicillin-resistant clones were selected and it was confirmed that they contained the respective -lactamase genes by isoelectric focusing. Detailed physical maps of 14 different recombinant plasmids were constructed using 8 restriction endonucleases. Plasmid deletions and lacZ fusions were used to localize the -lactamase structural genes. DNA probes were constructed for the TEM01, ROB-1, OXA-1, and PSE-1 genes. Under conditions of high stringency, hybridization was observed between the genes for TEM-1 and TEM-2 or TLE-1, OXA-1 and OXA-4, and PSE-1 and PSE-4 or CARB-3, while the ROB-1 gene probe showed no cross-hybridization. Such bla gene probes should facilitate studies of -lactamase molecular epidemiology.     

Long-chain acylcarnitine content determines the pattern of energy metabolism in cardiac mitochondria

In the heart, a nutritional state (fed or fasted) is characterized by a unique energy metabolism pattern determined by the availability of substrates. Increased availability of acylcarnitines has been associated with decreased glucose utilization; however, the effects of long-chain acylcarnitines on glucose metabolism have not been previously studied. We tested how changes in long-chain acylcarnitine content regulate the metabolism of glucose and long-chain fatty acids in cardiac mitochondria in fed and fasted states. We examined the concentrations of metabolic intermediates in plasma and cardiac tissues under fed and fasted states. The effects of substrate availability and their competition for energy production at the mitochondrial level were studied in isolated rat cardiac mitochondria. The availability of long-chain acylcarnitines in plasma reflected their content in cardiac tissue in the fed and fasted states, and acylcarnitine content in the heart was fivefold higher in fasted state compared to the fed state. In substrate competition experiments, pyruvate and fatty acid metabolites effectively competed for the energy production pathway; however, only the physiological content of acylcarnitine significantly reduced pyruvate and lactate oxidation in mitochondria. The increased availability of long-chain acylcarnitine significantly reduced glucose utilization in isolated rat heart model and in vivo. Our results demonstrate that changes in long-chain acylcarnitine contents could orchestrate the interplay between the metabolism of pyruvate–lactate and long-chain fatty acids, and thus determine the pattern of energy metabolism in cardiac mitochondria.     

Matrix Metalloproteinase-20 Over-Expression Is Detrimental to Enamel Development: A Mus musculus Model

Background

Matrix metalloproteinase-20 (Mmp20) ablated mice have enamel that is thin and soft with an abnormal rod pattern that abrades from the underlying dentin. We asked if introduction of transgenes expressing Mmp20 would revert this Mmp20 null phenotype back to normal. Unexpectedly, for transgenes expressing medium or high levels of Mmp20, we found opposite enamel phenotypes depending on the genetic background (Mmp20^−/− or Mmp20^+/+) in which the transgenes were expressed.

Methodology/Principal Findings

Amelx-promoter-Mmp20 transgenic founder mouse lines were assessed for transgene expression and those expressing low, medium or high levels of Mmp20 were selected for breeding into the Mmp20 null background. Regardless of expression level, each transgene brought the null enamel back to full thickness. However, the high and medium expressing Mmp20 transgenes in the Mmp20 null background had significantly harder more mineralized enamel than did the low transgene expresser. Strikingly, when the high and medium expressing Mmp20 transgenes were present in the wild-type background, the enamel was significantly less well mineralized than normal. Protein gel analysis of enamel matrix proteins from the high and medium expressing transgenes present in the wild-type background demonstrated that greater than normal amounts of cleavage products and smaller quantities of higher molecular weight proteins were present within their enamel matrices.

Conclusions/Significance

Mmp20 expression levels must be within a specific range for normal enamel development to occur. Creation of a normally thick enamel layer may occur over a wider range of Mmp20 expression levels, but acquisition of normal enamel hardness has a narrower range. Since over-expression of Mmp20 results in decreased enamel hardness, this suggests that a balance exists between cleaved and full-length enamel matrix proteins that are essential for formation of a properly hardened enamel layer. It also suggests that few feedback controls are present in the enamel matrix to prevent excessive MMP20 activity.