Sequential IgG antibody monitoring for virus-inactivated and adenovirus-vectored COVID-19 vaccine in Brazilian healthcare workers.

Vaccination certainly is the best way to fight against the COVID-19 pandemic. In this study, the seroconversion effectiveness of two vaccines against severe acute respiratory syndrome coronavirus 2 was assessed in healthcare workers: virus-inactivated CoronaVac (CV, n = 303), and adenovirus-vectored Oxford-AstraZeneca (AZ, n = 447). The immunoglobulin G (IgG) antibodies anti-spike glycoprotein and anti-nucleocapsid protein were assessed by enzyme-linked immunosorbent assay at the time before vaccination (T1), before the second dose (T2), and 30 days after the second dose (T3). Of all individuals vaccinated with AZ, 100% (n = 447) exhibited seroconversion, compared to 91% (n = 276) that were given CV vaccine. Among individuals who did not respond to the CV, only three individuals showed a significant increase in the antibody level 4 months later the booster dose. A lower seroconversion rate was observed in elders immunized with the CV vaccine probably due to the natural immune senescence, or peculiarity of this vaccine. The AZ vaccine induced a higher humoral response; however, more common side effects were also observed. Nonvaccinated convalescent individuals revealed a similar rate of anti-spike IgG to individuals that were given two doses of CV vaccine, which suggests that only a one-shot COVID-19 vaccine could produce an effective immune response in convalescents.

Why are 'suboptimal' temperatures preferred in a tropical intertidal ectotherm?

In thermally extreme environments, it is challenging for organisms to maximize performance due to risks associated with stochastic variation in temperature and, subsequently, over evolutionary time minimizing the exposure to risk can serve as one of the mechanisms that result in organisms preferring suboptimal temperatures. We tested this hypothesis in a slow-moving intertidal snail on tropical rocky shores, where temperature variability increases with time from 30 min to 20 hr when recorded at 30 min intervals (due to short-term environmental autocorrelation where temperatures closer in time are more similar as compared to temperatures over a long period of time). Failure to accommodate temporal variation in thermal stress by selecting cool habitats can result in mortality. Thermal performance curves for different traits (heart rate and locomotion) were measured and compared to the snail's thermal preferences in both the field and laboratory. Predicted performances of the snails were simulated based on thermal performance curves for different traits over multiple time-scales and simulated carryover effects. A strong mismatch was found between physiological and behavioural thermal maxima of the snails (physiological thermal maximum being higher by ~7°C), but the snails avoided these maxima and sought temperatures 7-14°C cooler. Such a risk-averse strategy can be explained by their predicted performances where the snails should make decisions about preferred temperatures based on time periods ≥5 hr to avoid underestimating the temporal variation in body temperature. In extreme and stochastic environments, where the temporal variation in environmental conditions can lead to substantial divergence between instantaneous and time-averaged thermal performances, 'cooler is better' and 'suboptimal' body temperatures are preferred as they provide sufficient buffer to reduce mortality risk from heat stress.

Preferred temperature of intertidal ectotherms: Broad patterns and methodological approaches.

Preferred temperature (Tpref) has been measured in over 100 species of aquatic and 300 species of terrestrial ectotherms as a metric for assessing behavioural thermoregulation in variable environments and, as such, has been linked to ecological processes ranging from individual behaviour to population and community dynamics. Due to the asymmetric shape of performance curves, Tpref is typically lower than the optimal temperature (Topt, where physiological performance is at its peak), and the degree of this mismatch increases with variability in Tb. Intertidal ectotherms experience huge variability in Tb on a daily basis and therefore provide a good system to test whether the relationship between Tpref and variation in Tb holds in more extreme environments. A review of the literature, however, only revealed comparisons between Tpref and Topt for five intertidal species and measurements of Tpref for 23 species. An analysis of this limited literature for intertidal ectotherms showed a positive relationship between acclimation temperature and Tpref. There was, however, great variation in the methodologies employed to make these assessments. Factors contributing to behavioural thermoregulation in intertidal ectotherms including small body size; low mobility; interactions among individuals; endogenous clocks; metabolic effects; thermal sensitivity; sampling of the thermal environment and recent acclimation history were considered to varying degrees when measuring Tpref, confounding comparisons between species. The methodologies used to measure Tpref in intertidal ectotherms were reviewed in light of each of these factors, and methodologies proposed to standardize approaches. Given the theoretical predictions about the relationships between Tpref and variability in Tb, the spatial and temporal thermal variability experienced by intertidal ectotherms provides numerous opportunities to test these expectations if assessed in a standardized manner, and can potentially provide insights into the value of behavioural thermoregulation in the more thermally variable environments predicted to occur in the near future.

[Enhancer of zeste homolog 2 affects dental pulp inflammation by regulating macrophage chemotaxis].

OBJECTIVE: To investigate the expression changes of the epigenetic regulator enhancer of zeste homolog 2 (EZH2) during pulp inflammation and the effect of EZH2 on macrophages migration. METHODS: Rat dental pulp was stimulated with 10 g/L lipopolysaccharide (LPS) to establish a model of rat pulpitis at different stages of inflammation. Immunohistochemical staining was used to detect the expression changes of EZH2 during the progression of pulp inflammation. Immunofluorescence double staining was used to detect the expression of EZH2, CD68 and their colocalization. To screen the appropriate concentration of EZH2 recombinant protein to stimulate hDPCs and human leukaemia-derived monocytic cell line (THP-1) cells, the effects of different concentrations (1, 10, 20, 40, and 100 µg/L) of EZH2 recombinant protein on proliferation of human dental pulp cells (hDPCs) and human monocyte cell line THP-1 were detected by cell counting kit-8 (CCK-8). Transwell migration assay was used to detect the effect of supernatants of hDPCs treated with EZH2 recombinant protein on the migration of THP-1 cells. RESULTS: HE staining results showed that in the model of rat pulp inflammation induced by LPS, with the prolongation of LPS stimulation, the inflammation response of pulp gradually increased. Immunohistochemical results showed that EZH2 expression decreased within 8 h of LPS-induced dental pulp inflammation; but after 1, 3, and 7 d of stimulation, EZH2 expression gradually increased with the extension of the stimulation time. As for the normal rat dental pulp tissue, the positive expression of EZH2 was scattered in the odontoblast cell layer and the pulp proper. Compared with the control group, LPS stimulated the expression of EZH2 and CD68 in the infected dental pulp, and the colocalization of EZH2 and CD68 could be detected in macrophages. The results of CCK-8 suggested that the appropriate concentration of EZH2 recombinant protein to stimulate hDPCs and THP-1 cells was 20 µg/L. Transwell cell migration assay confirmed that compared with the supernatant of EZH2 untreated HDPCs group, the supernatant of EZH2treated hDPCs significantly promoted macrophage chemotaxis. CONCLUSION: EZH2 is involved in the development of pulpitis and promotes the chemotaxis of macrophages, which suggests that EZH2 may play an important regulatory role in the development of pulp inflammation.

A systematic review and meta-analysis of clinical predictors of lithium response in bipolar disorder.

OBJECTIVE: To determine clinical predictors of lithium response in bipolar disorder. METHODS: Systematic review of studies examining clinical predictors of lithium response was conducted. Meta-analyses were performed when ≥2 studies examined the same potential predictor. RESULTS: A total of 71 studies, including over 12 000 patients, identified six predictors of good response: mania-depression-interval sequence [odds ratio (OR): 4.27; 95% CI: 2.61, 6.97; P < 0.001], absence of rapid cycling (OR for rapid cycling: 0.30; 95% CI: 0.17, 0.53; P < 0.001), absence of psychotic symptoms (OR for psychotic symptoms: 0.52; 95% CI: 0.34, 0.79; P = 0.002), family history of bipolar disorder (OR: 1.61; 95% CI: 1.03, 2.52; P = 0.036), shorter prelithium illness duration [standardised mean difference (SMD): -0.26; 95% CI: -0.41, -0.12; P < 0.001] and later age of onset (SMD: 0.17; 95% CI: 0.02, 0.36; P = 0.029). Additionally, higher body mass index was associated with poor response in two studies (SMD: -0.61; 95% CI: -0.90, -0.32; P < 0.001). There was weak evidence for number of episodes prior to lithium treatment (SMD: -0.42; 95% CI: -0.84, -0.01; P = 0.046), number of hospitalisations before lithium (SMD: -0.40; 95% CI: -0.81, 0.01; P = 0.055) and family history of lithium response (OR: 10.28; 95% CI: 0.66, 161.26; P = 0.097). CONCLUSIONS: The relative importance of these clinical characteristics should be interpreted with caution because of potential biases and confounding.

Predicting early recurrence of hepatocellular carcinoma with texture analysis of preoperative MRI: a radiomics study.

AIM: To investigate the feasibility of using texture analysis in preoperative magnetic resonance imaging (MRI) to predict early recurrence (ER) in hepatocellular carcinoma (HCC) post-curative surgery. MATERIAL AND METHODS: Institutional review board was obtained. A retrospective review of all patients who underwent hepatectomy between 1 January 2007 and 31 December 2015 was performed. Inclusion criteria included preoperative MRI, tumour size ≥1 cm, new cases of HCC. Exclusion criteria included loss to follow-up, ruptured HCCs, movement artefacts, and previous hepatectomy or interval adjuvant therapy. Patients were divided into ER and late or no recurrence (LNR) groups. ER was defined as new foci of HCC within 730 days of curative surgery. Radiomics feature extraction was performed on T2, diffusion-weighted imaging (DWI), T1 arterial, and T1 portovenous acquisitions on MATLAB (Mathworks, Matick, MA, USA). The MaZda software was used to analyse 290 texture parameters and PRTools was used for feature selection. RESULTS: Fifty patients (43 male, mean age 67 years) were divided into ER (n=20) and LNR (n=30) groups. Serum alpha-fetoprotein level (p=0.026), serum É£-glutamyltranspeptidase (p=0.014), Child-Pugh score (p=0.02) and the presence of vascular invasion (gross and/or microvascular, p=0.025) were found to be statistically significant different between the two groups. Parameters S(4,0)SumVarnc, S(0,3)SumOfSqs, and S(1,1)DifVarnc of the equilibrium phase were most accurate, achieving 84%, 82%, and 78% accuracy, respectively. CONCLUSION: Texture analysis of preoperative MRI has the potential to predict ER of HCC with up to 84% accuracy using an appropriate, single texture analysis parameter. Future studies are needed to validate these findings.

Does intra-tumoural fat on MRI predict visibility of small (≤3 cm) hepatocellular carcinomas during ultrasound-guided tumour ablation?

AIM: To assess if intra-tumoural fat on magnetic resonance imaging (MRI) affects the ultrasonographic (US) visibility of small (≤3 cm) hepatocellular carcinomas (HCC) during radiofrequency ablation (RFA). MATERIALS AND METHODS: Institutional review board approval was obtained. A retrospective review of all patients who underwent image-guided ablation between 1 January 2010 and 31 April 2015 was performed. Patients with HCC who underwent US RFA were included. Inclusion criteria included small tumours (≤3 cm), treatment-naive cases or new focus of HCC in a different and untreated segment, and pre-procedural MRI. The presence of intra-tumoural fat was determined retrospectively via in-and-out-of-phase MRI. Other factors that potentially affect ultrasonographic visibility, such as background fatty liver, presence of cirrhosis, tumour size, and distance from diaphragm, were recorded. RESULTS: Ninety procedures performed on 74 patients (62 men and 12 women; mean age: 67.3 years; range: 39-88 years). Seventy-two tumours were visible on US (hypoechoic n=35, hyperechoic n=28, heterogeneous n=9). Intra-tumoural fat was seen in 23 tumours (25.6%, hyperechoic n=17, hypoechoic n=6). The presence of intra-tumoural fat (p=0.005) and distance from diaphragm (p=0.007) were found to be statistically significant factors affecting tumour visibility on planning US. The presence of background fatty liver (p=0.485), cirrhosis (p=0.48), and tumour size (p=0.15) were not found to be significant. CONCLUSION: The present study shows that the presence of intra-tumoural fat in small HCCs on pre-procedural MRI can accurately predict their visibility on planning US during percutaneous tumour ablation.

Experience matters: context-dependent decisions explain spatial foraging patterns in the deposit-feeding crab Scopimera intermedia.

Behavioural decisions are often context-dependent, where information from immediate experience is incorporated into an individual's decision-making, particularly in complex environments. To test whether such mechanism is adopted by foragers in heterogeneous environments, we investigated the foraging behaviour of the deposit-feeding sand-bubbler crab, Scopimera intermedia An individual-based model was constructed, based on an optimal-patch selection criterion, which implicitly assumed that individuals adjust foraging decisions based on immediate past experience. The model's predictions were tested on the shore by manipulating the location of food patches, where the crab showed a strong context-dependent foraging pattern. When resources were randomly distributed, the crab responded by spending 56% of time in enriched patches compared with only 28% in the same area when patches were composed of natural sediments. Shore manipulations varying resource distribution supported the underlying principles of the model mechanism, and highlighted the benefits of such a strategy in heterogeneous environments such as intertidal sediments where food resources vary at different spatial and temporal scales. The proposed model therefore provides a mechanistic process, based on optimal foraging, to predict foraging decisions and movement patterns of animals feeding in heterogeneous landscapes.

Epigenetic regulation in dental pulp inflammation.

Dental caries, trauma, and other possible factors could lead to injury of the dental pulp. Dental infection could result in immune and inflammatory responses mediated by molecular and cellular events and tissue breakdown. The inflammatory response of dental pulp could be regulated by genetic and epigenetic events. Epigenetic modifications play a fundamental role in gene expression. The epigenetic events might play critical roles in the inflammatory process of dental pulp injury. Major epigenetic events include methylation and acetylation of histones and regulatory factors, DNA methylation, and small non-coding RNAs. Infections and other environmental factors have profound effects on epigenetic modifications and trigger diseases. Despite growing evidences of literatures addressing the role of epigenetics in the field of medicine and biology, very little is known about the epigenetic pathways involved in dental pulp inflammation. This review summarized the current knowledge about epigenetic mechanisms during dental pulp inflammation. Progress in studies of epigenetic alterations during inflammatory response would provide opportunities for the development of efficient medications of epigenetic therapy for pulpitis.

A randomised controlled trial of oral chloral hydrate vs. intranasal dexmedetomidine before computerised tomography in children.

Chloral hydrate is commonly used to sedate children for painless procedures. Children may recover more quickly after sedation with dexmedetomidine, which has a shorter half-life. We randomly allocated 196 children to chloral hydrate syrup 50 mg.kg-1 and intranasal saline spray, or placebo syrup and intranasal dexmedetomidine spray 3 µg.kg-1 , 30 min before computerised tomography studies. More children resisted or cried after drinking chloral hydrate syrup than placebo syrup, 72 of 107 (67%) vs. 42 of 87 (48%), p = 0.009, but there was no difference after intranasal saline vs. dexmedetomidine, 49 of 107 (46%) vs. 40 of 87 (46%), p = 0.98. Sedation was satisfactory in 81 of 107 (76%) children after chloral hydrate and 64 of 87 (74%) children after dexmedetomidine, p = 0.74. Of the 173 children followed up for at least 4 h after discharge, 38 of 97 (39%) had recovered normal function after chloral hydrate and 32 of 76 (42%) after dexmedetomidine, p = 0.76. Six children vomited after chloral hydrate syrup and placebo spray vs. none after placebo syrup and dexmedetomidine spray, p = 0.03.

Stimulatory role of the chemokine CCL2 in the migration and peptide expression of embryonic hypothalamic neurons.

Neuroinflammation is a feedback mechanism against infection, with recent studies suggesting a neuromodulatory role. The chemokine, (C-C motif) ligand 2 (CCL2), and its receptor, (C-C motif) receptor type 2 (CCR2), affect neuromodulation and migration in response to damage. Although CCL2 co-localizes with neuropeptides in the hypothalamus that control voluntary behavior, the function of CCL2/CCR2 is unknown. This led us to consider the possibility that CCL2 acting through CCR2, under natural conditions, may affect the migration and peptide levels of hypothalamic neurons that control voluntary behavior. This study used primary embryonic hypothalamic neurons to examine the effect of CCL2 on migratory behavior and on levels of the peptides, enkephalin (ENK) and galanin. Treatment with CCL2 led to a significant, dose-dependent increase in the number of migrated neurons and an increase in the velocity and distance traveled. CCL2 also significantly increased the number of ENK-expressing and CCR2/ENK co-expressing neurons and the percentage of neurons that contain higher levels of ENK. Lastly, CCL2 produced a dose-dependent increase in expression of ENK and galanin. These results provide evidence for a stimulatory effect of CCL2 on embryonic hypothalamic neurons involving changes in migratory behavior, expression, and synthesis of neuropeptides that function in controlling behavior. Our results demonstrate that the chemokine, CCL2, functions through its receptor, CCR2, to stimulate the migration and expression of the orexigenic peptides, enkephalin (ENK) and galanin (GAL), in developing embryonic hypothalamic neurons that are important for controlling ingestive behavior. This evidence reveals broad effects of CCL2 in the developing hypothalamus, showing this chemokine system to be tightly linked to the hypothalamic peptide neurons.

Suppression of tumour growth by orally administered osteopontin is accompanied by alterations in tumour blood vessels.

BACKGROUND: The integrin-binding protein osteopontin is strongly associated with tumour development, yet is an abundant dietary component as a constituent of human and bovine milk. Therefore, we tested the effect of orally administered osteopontin (o-OPN) on the development of subcutaneous tumours in mice. METHODS: Bovine milk osteopontin was administered in drinking water to tumour-bearing immune-competent mice. Tumour growth, proliferation, necrosis, apoptosis and blood vessel size and number were measured. Expression of the α9 integrin was determined. RESULTS: o-OPN suppressed tumour growth, increased the extent of necrosis, and induced formation of abnormally large blood vessels. Anti-OPN reactivity detected in the plasma of OPN-null mice fed OPN suggested that tumour-blocking peptides were absorbed during digestion, but the o-OPN effect was likely distinct from that of an RGD peptide. Expression of the α9 integrin was detected on both tumour cells and blood vessels. Potential active peptides from the α9 binding site of OPN were identified by mass spectrometry following in vitro digestion, and injection of these peptides suppressed tumour growth. CONCLUSIONS: These results suggest that peptides derived from o-OPN are absorbed and interfere with tumour growth and normal vessel development. o-OPN-derived peptides that target the α9 integrin are likely involved.

Volumetric deformation of live cells induced by pressure-activated cross-membrane ion transport.

In this work, we developed a method that allows precise control over changes in the size of a cell via hydrostatic pressure changes in the medium. Specifically, we show that a sudden increase, or reduction, in the surrounding pressure, in the physiologically relevant range, triggers cross-membrane fluxes of sodium and potassium ions in leukemia cell lines K562 and HL60, resulting in reversible volumetric deformation with a characteristic time of around 30 min. Interestingly, healthy leukocytes do not respond to pressure shocks, suggesting that the cancer cells may have evolved the ability to adapt to pressure changes in their microenvironment. A model is also proposed to explain the observed cell deformation, which highlights how the apparent viscoelastic response of cells is governed by the microscopic cross-membrane transport.

Effects of frying and boiling on the formation of heterocyclic amines in braised chicken.

Braised chicken is a traditional ready-to-eat poultry product produced by frying chicken coated with maltose or honey and then boiling it in a soup that is circularly used. This study examined the effects of the frying time, honey concentration, boiling time, and cycle times of the soup on the formation of heterocyclic amines (HA), a class of mutagenic/carcinogenic compounds generated in heated muscle meat. Nine HA in chicken and recycled soups were analyzed by HPLC with UV and fluorescence detection. 1-Methyl-9H-pyrido[3,4-b]indole (Harman), 9H-pyrido[3,4-b]indole (Norharman), and 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) were detected in most samples, and the amount of each HA increased with the frying or boiling time. Chicken skin was found to have higher HA content than chicken meat. More HA were detected in the soup than in the chicken, in most cases. 2-Amino-3-methylimidazo[4,5-f]quinoline and 2-amino-3,4,8-trimethylimidazoquinoxaline (4,8-DiMeIQx) were also detected in chicken and soup circularly boiled 20 times, and the total amount of HA reached 68.80 and 96.98 ng/g in chicken and soup, respectively.

Corrigendum: Introducing a healthcare-assistive robot in primary care: a preliminary questionnaire survey.

[This corrects the article DOI: 10.3389/frobt.2023.1123153.].

Introducing a healthcare-assistive robot in primary care: a preliminary questionnaire survey.

A Healthcare-assistive Infection-control RObot (HIRO) is a healthcare-assistive robot that is deployed in an outpatient primary care clinic to sanitise the premises, monitor people in its proximity for their temperature and donning of masks, and usher them to service points. This study aimed to determine the acceptability, perceptions of safety, and concerns among the patients, visitors, and polyclinic healthcare workers (HCWs) regarding the HIRO. A cross-sectional questionnaire survey was conducted from March to April 2022 when the HIRO was at Tampines Polyclinic in eastern Singapore. A total of 170 multidisciplinary HCWs serve approximately 1,000 patients and visitors daily at this polyclinic. The sample size of 385 was computed using a proportion of 0.5, 5% precision, and 95% confidence interval. Research assistants administered an e-survey to gather demographic data and feedback from 300 patients/visitors and 85 HCWs on their perceptions of the HIRO using Likert scales. The participants watched a video on the HIRO's functionalities and were given the opportunity to directly interact with it. Descriptive statistics was performed and figures were presented in frequencies and percentages. The majority of the participants viewed the HIRO's functionalities favourably: sanitising (96.7%/91.2%); checking proper mask donning (97%/89.4%); temperature monitoring (97%/91.7%); ushering (91.7%/81.1%); perceived user friendliness (93%/88.3%), and improvement in the clinic experience (96%/94.2%). A minority of the participants perceived harm from the HIRO's liquid disinfectant (29.6%/31.5%) and that its voice-annotated instructions may be upsetting (14%/24.8%). Most of the participants accepted the HIRO's deployment at the polyclinic and perceived it to be safe. The HIRO used ultraviolet irradiation for sanitisation during after-clinic hours instead of disinfectants due to the perceived harm.

Systematic Review and Meta-Analysis of the Influence of Genetic Variation on Ototoxicity in Platinum-Based Chemotherapy.

OBJECTIVE: The objective of this meta-analysis is to evaluate the impact of genetic polymorphisms on platinum-based chemotherapy (PBC)-induced ototoxicity. DATA SOURCES: Systematic searches of PubMed, Embase, Cochrane, and Web of Science were conducted from the inception of the databases to May 31, 2022. Abstracts and presentations from conferences were also reviewed. REVIEW METHODS: Four investigators independently extracted data in adherence to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Differences in the prevalence of PBC-induced ototoxicity between reference and variant (i) genotypes and (ii) alleles were analyzed. The overall effect size was presented using the random-effects model as an odds ratio (OR) with a 95% confidence interval (CI). RESULTS: From 32 included articles, 59 single nucleotide polymorphisms on 28 genes were identified, with 4406 total unique participants. For allele frequency analysis, the A allele in ACYP2 rs1872328 was positively associated with ototoxicity (OR: 2.61; 95% CI: 1.06-6.43; n = 2518). Upon limiting to cisplatin use only, the T allele of COMT rs4646316 and COMT rs9332377 revealed significant results. For genotype frequency analysis, the CT/TT genotype in ERCC2 rs1799793 demonstrated an otoprotective effect (OR: 0.50; 95% CI: 0.27-0.94; n = 176). Excluding studies using carboplatin or concomitant radiotherapy revealed significant effects with COMT rs4646316, GSTP1 rs1965, and XPC rs2228001. Major sources of variations between studies include differences in patient demographics, ototoxicity grading systems, and treatment protocols. CONCLUSION: Our meta-analysis presents polymorphisms that exert ototoxic or otoprotective effects in patients undergoing PBC. Importantly, several of these alleles are observed at high frequencies globally, highlighting the potential for polygenic screening and cumulative risk evaluation for personalized care.

A randomised comparison of two intranasal dexmedetomidine doses for premedication in children.

We compared sedation levels in children following administration of intranasal dexmedetomidine. One hundred and sixteen children aged between 1 and 8 years were enrolled in this prospective, randomised trial. Children were assigned to receive either intranasal dexmedetomidine 1 µg.kg(-1) (Group 1) or 2 µg.kg(-1) (Group 2). Thirty-one (53%) patients from Group 1 and 38 (66%) patients from Group 2 were satisfactorily sedated at the time of anaesthetic induction. Logistic regression showed a significant interaction effect (p=0.049), with the odds ratio between Group 2 over Group 1 estimated as 1.1 (95% CI 0.5-2.7) for the 1-4 year age group, and 10.5 (95% CI 1.4-80.2) for the 5-8 year age group. Both doses produced a similar level of satisfactory sedation in children aged 1-4 years, whereas 2 µg.kg(-1) resulted in a higher proportion of satisfactory sedation in children aged 5-8 years. There were no adverse haemodynamic effects. We conclude that intranasal dexmedetomidine in a premedication dose of 2 µg.kg(-1) resulted in excellent sedation in children.