Investigations of the intestinal tolerance of hydroxyethyl starch: Establishment and validation of a new isolated perfused mouse intestine model

Im klinischen Einsatz werden bei intravasalem Volumenmangel neben kristalloiden auch kolloidale Infusionslösungen wie die Hydroxyethylstärke (HES) zur Therapie eingesetzt. Das Ziel dieser Flüssigkeitssubstitution ist eine Wiederherstellung des intravasalen Volumens und die Vermeidung von kardiovaskulär bedingter Hypoxie in Organen und Geweben. Aktuell wird der klinische Einsatz von HES kontrovers diskutiert, da neue Studien ein ungünstiges Nutzen-Risiko-Verhältnis für HES aufzeigten. Bislang wurde die intestinale Wirkung einer HES-Perfusion sowie die assoziierten physiologischen und zellulären Mechanismen trotz der hohen klinischen Relevanz des Darms im Rahmen der Sepsis und Ödembildung kaum untersucht, was unter anderem auch auf das Fehlen geeigneter ex vivo Modelle zurückzuführen ist. Das Ziel der vorliegenden Arbeit war die Analyse der physiologischen und zellulären Effekte einer vaskulären Perfusion mit HES auf die intestinale endotheliale und epitheliale Permeabilität unter Verwendung eines neu etablierten ex vivo Mausdünndarm-Modells. Hierzu wurden Dünndärme aus C57/BL6 Mäusen unter Sevofluran/Ketamin-Narkose isoliert und an ein für das Mausmodell modifiziertes Perfusionssystem angeschlossen. Für die erfolgreiche Etablierung mussten zahlreiche systemspezifische Anpassungen vorgenommen werden. Neben Veränderungen an den Kanülen, der Perfusionsparameter und der Waagen, wurde eine neue Vorrichtung für den Transfer des isolierten Mausdünndarms (in vivo) in die Perfusionskammer (ex vivo) entwickelt. Zur Validierung des Modells wurden die Mausdünndärme vaskulär mit 3 % Rinderserumalbumin (BSA) in modifiziertem Krebs-Henseleit-Puffer perfundiert (Kontrollgruppe) und in einer weiteren Gruppe mit einem Bolus Plättchen aktivierender Faktor (PAF) stimuliert. Für die Untersuchung der intestinalen Verträglichkeit von HES wurde das vaskuläre Perfusat nach 60 Minuten Equilibrierungsphase von 3 % BSA auf 3 % HES 130/0,4 bzw. HES 200/0,5 gewechselt. Folgende Parameter wurden untersucht: Perfusionsraten und Perfusionsdrücke, die Flüssigkeitshomöostase, die Barriereintegrität, die luminale Galaktoseaufnahme, die Histomorphologie, das Laktat zu Pyruvat Verhältnis, das Feucht- zu Trockengewicht, die Sauerstoffaufnahme, der pH-Wert der Perfusate, die Darmmotilität und die Gewichtsveränderung des Darms. Die Barriereintegrität wurde anhand der Übertrittsrate des vaskulär applizierten FITC-Dextrans in das interstitielle und das luminale Effluat bestimmt. Nach der Perfusion wurden elektronenmikroskopische Aufnahmen des Darms in der Kontrollgruppe und der HES 130/0,4-Gruppe angefertigt. Es wurde sowohl für die Kontrollgruppe als auch für die Gruppe mit PAF-Stimulus eine intakte Flüssigkeitshomöostase, Barrierefunktion und luminale Galaktoseaufnahme über die Versuchsdauer nachgewiesen. Bis auf histomorphologische Schäden am Darmepithel zeigten die untersuchten Parameter einen funktionell intakten, isoliert perfundierten Mausdünndarm. Eine Umstellung des vaskulären Perfusats von 3 % BSA auf 3 % HES 130/0,4 oder 3 % HES 200/0,5 führte zu signifikanten Veränderungen in der Funktion, Flüssigkeitshomöostase, Permeabilität und Morphologie des Mausdünndarms. Die vaskuläre Perfusion mit HES verursachte eine signifikante Zunahme bei der Flüssigkeitsverschiebung vom vaskulären zum luminalen Kompartiment, was eine Störung der endothelialen und epithelialen Barrierefunktion suggerierte. Dieser Befund wurde durch die Ergebnisse des FITC-Dextran-Transfers unterstützt. Das vaskulär applizierte FITC-Dextran konnte unter Kontrollbedingungen die endotheliale und epitheliale Barriere nicht überwinden und war luminal nur in geringen Mengen nachweisbar. Bei der vaskulären Perfusion mit HES stieg der FITC-Dextran-Transfer von vaskulär nach luminal aufgrund der zunehmenden Permeabilisierung der Barriere signifikant an. Zudem konnten in elektronenmikroskopischen Aufnahmen histomorphologische Veränderungen in Form von vermehrten intrazellulären Vakuolen und erweiterten interzellulären Spalten im Darmepithel nach einer HES-Perfusion nachgewiesen werden. Zusätzlich führte die Perfusion mit HES zu einer signifikanten Reduktion der luminalen Galaktoseaufnahme, was eine mögliche Störung der Resorptionsprozesse im Darm durch HES zeigte. In der vorliegenden Arbeit konnte das isoliert perfundierte Mausdünndarm-Modell erfolgreich etabliert und validiert werden. Eine Perfusion mit 3 % HES führte im verwendeten ex vivo Maus-Modell zu einer Störung der Flüssigkeitshomöostase und erhöhter Permeabilität des Endothels und Epithels mit signifikanten histomorphologischen Veränderungen des Epithels. Als vaskuläres Perfusat war das eingesetzte HES im isoliert perfundierten Mausdünndarm unverträglich. Dieser Befund unterstützt die Empfehlung der europäischen Arzneimittelagentur wonach eine HES-Therapie bei Sepsis und schwerkranken Patienten nicht eingesetzt werden soll.For the clinical therapy of acute volume deficiency cristalloids and colloids like hydroxyethyl starch (HES) are often used for the substitution of fluids and restoration of intravascular volume to avoid cardiovascular caused hypoxia in organs and tissues. The usage of HES is currently controversially discussed due to recent studies which show a negative benefit-risk-ratio. Clinical situations with intestinal related problems like sepsis and edema formation are common and improved knowledge about the physiological and cellular mechanisms is needed. Up to now the intestinal effect of HES perfusion has not been well investigated owing to the absence of suitable ex vivo models. The goal of this work was to study the physiological and cellular effects of vascular HES perfusion on the intestinal endothelial and epithelial permeability. For this purpose an ex vivo small intestine mouse model was established. The small intestine was isolated from with sevoflurane and ketamine anesthetized C57/BL6 mice. Numerous changes like the modification of the cannulas, perfusion parameters and electronic balances were needed to establish a specific perfusion system. A newly developed transport device ensures the transfer of the small intestine in vivo into the perfusion chamber ex vivo. For validation purposes a modified Krebs-Henseleit solution with 3 % bovine serum albumin (BSA) was used (control group) with or without an additional bolus of platelet-activating factor (PAF). To investigate the intestinal tolerance to HES 3 % BSA was used in the equilibration phase and switched to 3 % HES 130/0.4 and 3 % HES 200/0.5, respectively. Perfusion rate, perfusion pressure, fluid homeostasis, barrier integrity, luminal galactose uptake, histomorphology, lactate to pyruvate ratio, wet to dry weight ratio, oxygen uptake, perfusate pH, bowel motility and bowel weight changes were observed. Barrier integrity was measured by vascularly applied FITC-dextran and its transfer rate into the interstitial and luminal compartment. Electron micrographs were taken in the control group and HES 130/0.4 group after perfusion. The fluid homeostasis, barrier integrity, and luminal galactose uptake during perfusion was intact in the control group as well as in the PAF group. Observed parameters confirmed a functional intestine despite apparent histomorphological damage in intestinal epithelia. In comparison a perfusion with HES 130/0.4 or HES 200/0.5 led to significant alteration in fluid distribution from vascular into the luminal compartment. This was accompanied by a significant increment of FITC-dextran transfer from the vascular to luminal side, demonstrating a barrier dysfunction and increased permeability after HES perfusion. In normal cases vascularly applied FITC-dextran cannot permeate the endothelial and epithelial barrier and only small amounts of FITC-dextran are luminally detectable. Electron micrographs showed histomorphological changes with extended intercellular spaces and increased intracellular vacuoles. Perfusion with HES reduced the luminal galactose uptake significantly and suggested dysfunction in resorption. The present work presents a successful establishment and validation of an isolated perfused mouse small intestine. Perfusion with HES showed dysfunction in fluid homeostasis and increased endothelial and epithelial permeability. Histomorphological alterations were observed and support the assumption of intestinal intolerance for vascular HES perfusion in mice. These results support the recommendation of the European medicine agency to avoid HES therapy in sepsis and critically ill patients

Equivalent stress block for normal-strength concrete incorporating strain gradient effect

To account for the different behaviours of concrete under uniaxial compression and bending in the flexural strength design of reinforced concrete (RC) members, the stress-strain curve of concrete is normally scaled down so that the adopted maximum concrete stress in flexural members is less than the uniaxial strength. However, it was found from previous experimental research that the use of a smaller maximum concrete stress would underestimate the flexural strength of RC beams and columns. To investigate the effect of strain gradient on the maximum concrete stress developed in flexure, a total of 12 plain concrete and RC inverted T-shaped specimens were fabricated and tested under concentric and eccentric loads separately. The maximum concrete stress developed in the eccentric specimens was determined by modifying the concrete stress-strain curve obtained from the counterpart concentric specimens based on axial force and moment equilibriums. The test results revealed that the maximum concrete stress increases with strain gradient up to a certain maximum value. A formula was developed to correlate the maximum concrete stress to strain gradient. A pair of equivalent rectangular concrete stress block parameters that incorporate the effects of strain gradient was proposed for flexural strength design of RC members

Effects of different ischemic preconditioning strategies on physiological and cellular mechanisms of intestinal ischemia/reperfusion injury: Implication from an isolated perfused rat small intestine model

Background Intestinal ischemia/reperfusion (I/R)-injury often results in sepsis and organ failure and is of major importance in the clinic. A potential strategy to reduce I/R-injury is the application of ischemic preconditioning (IPC) during which repeated, brief episodes of I/R are applied. The aim of this study was to evaluate physiological and cellular effects of intestinal I/R-injury and to compare the influence of in-vivo IPC (iIPC) with ex-vivo IPC (eIPC), in which blood derived factors and nerval regulations are excluded. Results I/R-injury decreased intestinal galactose uptake (iIPC group: p<0.001), increased vascular perfusion pressure (iIPC group: p<0.001; eIPC group: p<0.01) and attenuated venous flow (iIPC group: p<0.05) while lactate-to-pyruvate ratio (iIPC group, eIPC group: p<0.001), luminal flow (iIPC group: p<0.001; eIPC group: p<0.05), goblet cell ratio (iIPC group, eIPC group: p<0.001) and apoptosis (iIPC group, eIPC group: p<0.05) were all increased. Application of iIPC prior to I/R increased vascular galactose uptake (P<0.05) while eIPC had no significant impact on parameters of I/R-injury. On cellular level, I/R-injury resulted in a reduction of the phosphorylation of several MAPK signaling molecules. Application of iIPC prior to I/R increased phosphorylation of JNK2 and p38δ while eIPC enhanced CREB and GSK-3α/β phosphorylation. Conclusion Intestinal I/R-injury is associated with major physiological and cellular changes. However, the overall influence of the two different IPC strategies on the acute phase of intestinal I/R-injury is rather limited

Comparing hybrid and regular COVID-19 vaccine-induced immunity against the Omicron epidemic

Evidence on the effectiveness of COVID-19 vaccines among people who recovered from a previous SARS-CoV-2 infection is warranted to inform vaccination recommendations. Using the territory-wide public healthcare and vaccination records of over 2.5 million individuals in Hong Kong, we examined the potentially differential risk of SARS-CoV-2 infection, hospitalization, and mortality between those receiving two homologous doses of BNT162b2 or CoronaVac versus those with a previous infection receiving only one dose amid the Omicron epidemic. Results show a single dose after a SARS-CoV-2 infection is associated with a lower risk of infection (BNT162b2: adjusted incidence rate ratio [IRR] = 0.475, 95% CI: 0.410–0.550; CoronaVac: adjusted IRR = 0.397, 95% CI: 0.309–0.511) and no significant difference was detected in the risk of COVID-19-related hospitalization or mortality compared with a two-dose vaccination regimen. Findings support clinical recommendations that those with a previous infection could receive a single dose to gain at least similar protection as those who received two doses without a previous infection

Risk of thyroid dysfunction associated with mRNA and inactivated COVID-19 vaccines: a population-based study of 2.3 million vaccine recipients

Background: In view of accumulating case reports of thyroid dysfunction following COVID-19 vaccination, we evaluated the risks of incident thyroid dysfunction following inactivated (CoronaVac) and mRNA (BNT162b2) COVID-19 vaccines using a population-based dataset. / Methods: We identified people who received COVID-19 vaccination between 23 February and 30 September 2021 from a population-based electronic health database in Hong Kong, linked to vaccination records. Thyroid dysfunction encompassed anti-thyroid drug (ATD)/levothyroxine (LT4) initiation, biochemical picture of hyperthyroidism/hypothyroidism, incident Graves’ disease (GD), and thyroiditis. A self-controlled case series design was used to estimate the incidence rate ratio (IRR) of thyroid dysfunction in a 56-day post-vaccination period compared to the baseline period (non-exposure period) using conditional Poisson regression. / Results: A total of 2,288,239 people received at least one dose of COVID-19 vaccination (57.8% BNT162b2 recipients and 42.2% CoronaVac recipients). 94.3% of BNT162b2 recipients and 92.2% of CoronaVac recipients received the second dose. Following the first dose of COVID-19 vaccination, there was no increase in the risks of ATD initiation (BNT162b2: IRR 0.864, 95% CI 0.670–1.114; CoronaVac: IRR 0.707, 95% CI 0.549–0.912), LT4 initiation (BNT162b2: IRR 0.911, 95% CI 0.716–1.159; CoronaVac: IRR 0.778, 95% CI 0.618–0.981), biochemical picture of hyperthyroidism (BNT162b2: IRR 0.872, 95% CI 0.744–1.023; CoronaVac: IRR 0.830, 95% CI 0.713–0.967) or hypothyroidism (BNT162b2: IRR 1.002, 95% CI 0.838–1.199; CoronaVac: IRR 0.963, 95% CI 0.807–1.149), GD, and thyroiditis. Similarly, following the second dose of COVID-19 vaccination, there was no increase in the risks of ATD initiation (BNT162b2: IRR 0.972, 95% CI 0.770–1.227; CoronaVac: IRR 0.879, 95%CI 0.693–1.116), LT4 initiation (BNT162b2: IRR 1.019, 95% CI 0.833–1.246; CoronaVac: IRR 0.768, 95% CI 0.613–0.962), hyperthyroidism (BNT162b2: IRR 1.039, 95% CI 0.899–1.201; CoronaVac: IRR 0.911, 95% CI 0.786–1.055), hypothyroidism (BNT162b2: IRR 0.935, 95% CI 0.794–1.102; CoronaVac: IRR 0.945, 95% CI 0.799–1.119), GD, and thyroiditis. Age- and sex-specific subgroup and sensitivity analyses showed consistent neutral associations between thyroid dysfunction and both types of COVID-19 vaccines. / Conclusions: Our population-based study showed no evidence of vaccine-related increase in incident hyperthyroidism or hypothyroidism with both BNT162b2 and CoronaVac

Effectiveness of a denture hygiene intervention programme among institutionalized elders

Objectives: To evaluate the effectiveness of a denture hygiene intervention programme in terms of improving denture cleanliness and denture stomatitis. Methods: Residents at seven elderly care homes were invited to participate in a denture hygiene programme. Clinical assessment of denture stomatitis was undertaken and denture cleanliness assessed: (i) qualitatively by the Denture Cleanliness Index ratings and (ii) quantitatively by planimetric assessments of plaque coverage from digital images using Adobe Photoshop®. Individual denture hygiene instruction was provided and denture cleanser (Polident®) supplied. Six weeks later assessments of denture stomatitis and denture cleanliness were undertaken. Results: Fifty-six participants were recruited; most had evidence of denture stomatitis (82.1%, 46) and 62.5% (35) of dentures were classified as ‘very poorly cleaned’. The mean percentage of plaque coverage was 28.11 (SD 19.64) and 37.5% (21) had evidence of plaque covering more than a third of the denture surface. Denture cleanliness was associated with denture stomatitis (P0.05).Conclusion: A 6-week denture hygiene intervention programme was effective at improving denture stomatitis and denture cleanliness among residents of elderly care homes. However, persistence of problems in denture cleanliness and denture stomatitis existed and this warrants further consideration.published_or_final_versio

Effectiveness of a denture hygiene intervention programme among institutionalized elders

Objectives: To evaluate the effectiveness of a denture hygiene intervention programme in terms of improving denture cleanliness and denture stomatitis. Methods: Residents at seven elderly care homes were invited to participate in a denture hygiene programme. Clinical assessment of denture stomatitis was undertaken and denture cleanliness assessed: (i) qualitatively by the Denture Cleanliness Index ratings and (ii) quantitatively by planimetric assessments of plaque coverage from digital images using Adobe Photoshop®. Individual denture hygiene instruction was provided and denture cleanser (Polident®) supplied. Six weeks later assessments of denture stomatitis and denture cleanliness were undertaken. Results: Fifty-six participants were recruited; most had evidence of denture stomatitis (82.1%, 46) and 62.5% (35) of dentures were classified as ‘very poorly cleaned’. The mean percentage of plaque coverage was 28.11 (SD 19.64) and 37.5% (21) had evidence of plaque covering more than a third of the denture surface. Denture cleanliness was associated with denture stomatitis (P0.05).Conclusion: A 6-week denture hygiene intervention programme was effective at improving denture stomatitis and denture cleanliness among residents of elderly care homes. However, persistence of problems in denture cleanliness and denture stomatitis existed and this warrants further consideration.published_or_final_versio

COVID-19 vaccine effectiveness against the Omicron variant of SARS-CoV-2 in multimorbidity: A territory-wide case-control study

Multimorbidity entails a higher risk of SARS-CoV-2 infection and COVID-19 complications. We examined vaccine effectiveness (VE) stratified by multimorbidity using a case-control study of territory-wide electronic health records in Hong Kong. Cases of infection (testing positive), hospitalization, and mortality were identified from January to March 2022. Controls were matched by age, sex, outpatient attendance/hospitalization date, and Charlson Comorbidity Index. We demonstrated a consistently good VE among people with increased multimorbidity burden; even more so than among those with minimal such burden. There was also a significantly greater VE after a third dose of BNT162b2 or CoronaVac against infection. The difference in VE between those with multimorbidity and those without was less pronounced for hospitalization, and such difference for COVID-19-related mortality was negligible. In conclusion, VE of both examined vaccines against SARS-CoV-2 infection among people with more complex multimorbidity burden is significant. Further vaccine roll-out should prioritize people with multimorbidity

Genome-Wide Association Study in Asian Populations Identifies Variants in ETS1 and WDFY4 Associated with Systemic Lupus Erythematosus

Systemic lupus erythematosus is a complex and potentially fatal autoimmune disease, characterized by autoantibody production and multi-organ damage. By a genome-wide association study (320 patients and 1,500 controls) and subsequent replication altogether involving a total of 3,300 Asian SLE patients from Hong Kong, Mainland China, and Thailand, as well as 4,200 ethnically and geographically matched controls, genetic variants in ETS1 and WDFY4 were found to be associated with SLE (ETS1: rs1128334, P = 2.33×10−11, OR = 1.29; WDFY4: rs7097397, P = 8.15×10−12, OR = 1.30). ETS1 encodes for a transcription factor known to be involved in a wide range of immune functions, including Th17 cell development and terminal differentiation of B lymphocytes. SNP rs1128334 is located in the 3′-UTR of ETS1, and allelic expression analysis from peripheral blood mononuclear cells showed significantly lower expression level from the risk allele. WDFY4 is a conserved protein with unknown function, but is predominantly expressed in primary and secondary immune tissues, and rs7097397 in WDFY4 changes an arginine residue to glutamine (R1816Q) in this protein. Our study also confirmed association of the HLA locus, STAT4, TNFSF4, BLK, BANK1, IRF5, and TNFAIP3 with SLE in Asians. These new genetic findings may help us to gain a better understanding of the disease and the functions of the genes involved

Current Antiviral Therapy of Chronic Hepatitis B: Efficacy and Safety

The treatment of chronic hepatitis B is in constant evolution. Interferon, the first agent licensed for chronic hepatitis B treatment, has been superseded by the growing popularity of nucleoside/nucleotide analogues (NA). However, resistance to these agents is a major challenge. Newer NAs, such as entecavir and tenofovir dipivoxil fumarate, have very low resistance rates and favorable safety profiles. Long-term use of these agents can effectively suppress hepatitis B virus DNA, leading to decrease in incidence of hepatitic flares, as well as in the development of cirrhosis and hepatocellular carcinoma. The efficacy and safety of various antiviral agents is discussed in this review