Profound increase ofHelicobacter pylori urease activity in gastric antral mucosa at low pH

Miederer, S. E.; Grubel, Peter

doi:10.1007/bf02091535

Cited by 24 publications

(24 citation statements)

References 26 publications

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“…Cells are generally negatively charged hence strong electrostatic interactions would be originated towards positively charged particles, however surfaces appendices present on cell can overcome the possible repulsive barrier observed when facing negatively charged surfaces; evidence has shown that positively nanoparticles have higher toxicity than negatively charged ones [45]. Human body pH is generally close to neutral, however there are some fluids that exhibit extreme acidity (stomach is about pH = 3.5 [46]) or alkalinity (pancreatic fluid is about pH = 8.8 [47]) therefore the pH range employed for our studies covers such spectrum. Unfunctionalised particles exhibit hydroxyl groups on the surface that behave as weak acid; hence they are protonated and nearly neutral at pH values up to about 7, while they are deprotonated, and with negative charge, in alkaline solutions.…”

Section: Discussionmentioning

confidence: 99%

Controlling release kinetics of gentamicin from silica nano-carriers

Perni

Martini-Gilching

Prokopovich

2018

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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Antibiotic release from a carrier can be employed to reduce the frequency of administration or prolong efficacy. In this work, we prepared silica nanoparticles loaded with gentamicin through different synthetis routes (entrapment, adsorption, covalent bonding and Layer-by-Layer (LbL) techniques). The nanocarriers physical-chemical properties were characterised and antibiotic release from the nanocarriers was monitored. The nanoparticles prepared entrapping gentamicin gave the highest drug load but completed the release over a period of 4 hours. No significant differences in antibiotic load were noticed between absorption or binding of gentamicin onto the silica nanoparticles surface; moreover the release of the drug occurred over 2 days. The nanoparticles coated with gentamicin through LbL technique released the antibiotic for 3 weeks. This work demonstrates that silica nanoparticles can be employed as antibiotic carriers providing a continuous release of antibiotic over a period that can be tuned through the choice of preparation method.

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Section: Discussionmentioning

confidence: 99%

Controlling release kinetics of gentamicin from silica nano-carriers

Perni

Martini-Gilching

Prokopovich

2018

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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“…However, immediate improvement in the rapid urease test at pH 7.0 found with acidification cannot be due to an immediate change in the bacterial load. [37][38][39] Thus the explanation for the decrease in UBT during proton pump inhibitor treatment is more likely due to the pH increase induced by proton pump inhibitors and a decrease in intra-bacterial urease activity because of inactivation of urea entry into the organism. After chronic therapy, a decrease in the number of bacteria may also contribute to the decrease in UBT.…”

Section: Discussionmentioning

confidence: 99%

13C urea breath test (UBT) in the diagnosis of Helicobacter pylori: why does it work better with acid test meals?

Pantoflickova¹

2003

Gut

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Background: Acid test meals may improve the accuracy of the 13 C urea breath test (UBT). This has been attributed to changes in gastric emptying rather than to the effects of gastric pH on Helicobacter pylori urease. Aims: To determine whether enhancement of 13 CO 2 excretion in the UBT in H pylori infected volunteers by acidification of a test meal is due to a delay in gastric emptying. Methods: Urease activity in vitro was measured in intact bacteria and in bacterial homogenates. Urease activity in vivo was assessed by means of the UBT. Eleven H pylori infected subjects underwent UBTs with neutral Ensure (pH 7.0), acidified Ensure (pH 3.0), and apple juice (pH 3.0). Gastric emptying was assessed by 13 C sodium acetate breath test. Results: From pH 7 to pH 3, the in vitro urease activity of intact bacteria increased sixfold. In contrast, urease activity of bacterial homogenates was inactivated by low pH. In vivo, urease activity, as measured by the UBT 20 minutes after meal ingestion, was higher with apple juice (δ 13 CO 2 =21.1; p=0.03) and acidified Ensure (δ 13 CO 2 =25.5; p=0.01) than with neutral Ensure (δ 13 CO 2 =12.5). Gastric emptying was faster with apple juice (T max =36.7 (8) minutes) but not with acidified Ensure (T max =63.3 (5) minutes; p=0.06) than with neutral Ensure (T max =65.0 (3) minutes; p=0.04). Conclusions: The higher UBT found with acidified compared with neutral test meals was independent of the emptying rates of the test meals but may have been due to medium acidity dependent activation of intra-bacterial urease in intact H pylori.

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“…In agreement with our ndings, Rauws and coworkers (22) found that an increased retention time of gastric contents resulted in increased resolution of the test, permitting lower doses of 1 4 C-urea to reliably detect H. pylori. Furthermore, urease activity in antrum biopsies is highly increased at low pH (23) and maximal urease activity in vivo seems to depend on acid-stimulated activation of internal urease (24). Thus, an acidic medium slows gastric emptying and increases hydrolysis of urea, which promotes greater resolution of the UBT (25,26).…”

Section: Discussionmentioning

confidence: 96%