Gut microbiota and metabolic biomarkers in metabolic dysfunction-associated steatotic liver disease

Metabolic dysfunction-associated steatotic liver disease (MASLD), a replacement of the nomenclature employed for NAFLD, is the most prevalent chronic liver disease worldwide. Despite its high global prevalence, NAFLD is often under-recognized due to the absence of reliable noninvasive biomarkers for diagnosis and staging. Growing evidence suggests that the gut microbiome plays a significant role in the occurrence and progression of NAFLD by causing immune dysregulation and metabolic alterations due to gut dysbiosis. The rapid advancement of sequencing tools and metabolomics has enabled the identification of alterations in microbiome signatures and gut microbiota-derived metabolite profiles in numerous clinical studies related to NAFLD. Overall, these studies have shown a decrease in α-diversity and changes in gut microbiota abundance, characterized by increased levels of Escherichia and Prevotella, and decreased levels of Akkermansia muciniphila and Faecalibacterium in patients with NAFLD. Furthermore, bile acids, short-chain fatty acids, trimethylamine N-oxide, and tryptophan metabolites are believed to be closely associated with the onset and progression of NAFLD. In this review, we provide novel insights into the vital role of gut microbiome in the pathogenesis of NAFLD. Specifically, we summarize the major classes of gut microbiota and metabolic biomarkers in NAFLD, thereby highlighting the links between specific bacterial species and certain gut microbiota-derived metabolites in patients with NAFLD.

[Nutritional status of 15 children with progeria]

Objective: To analyze the nutritional status of progeria, and to provide reference for scientific nutritional management of progeria. Methods: This cross-sectional study included 15 children with progeria who were treated at Children's Hospital, Zhejiang University School of Medicine, between April 2022 and May 2023. Data of medical history, physical examination, laboratory tests, dietary survey and body composition were collected and analyzed. Results: Among 15 patients there were 7 males and 8 females, aged 7.8 (2.3, 10.8) years. Twelve of the 15 patients exhibited signs of malnutrition. A 24-hour dietary survey was carried out in 14 of them. The daily energy intake of 11 cases was below recommended levels. Carbohydrate intake was insufficient in 10 cases, protein intake was insufficient in 7 cases, and fat intake was insufficient in 12 cases. Deficiencies in calcium, magnesium, iron and zinc were noted in 13, 13, 9 and 10 cases, respectively. Body composition was determined by dual-energy X-ray absorptiometry in 8 cases, and the bone mineral density was below average in 5 of them. Conclusions: Malnutrition, characterized by reduced energy intake, micronutrient deficiencies, and alteration in body composition, is prevalent in children with progeria. Regular routine nutritional assessment and proper interventions may benefit their long-term health status.

Pretreatment synthetic MRI features for triple-negative breast cancer

AIM

To evaluate the quantitative parameters derived from synthetic magnetic resonance imaging (SyMRI) for predicting triple-negative breast cancer (TNBC).

MATERIALS AND METHODS

This prospective study enrolled participants with invasive ductal breast carcinoma (IDBC) and separated them into a TNBC group and a Non-TNBC group. Preoperative breast MRI included both the SyMRI and conventional MRI sequences. The quantitative parameters derived from the SyMRI included T1 and T2 relaxation times, proton density (PD), and their standard deviations (SD). Clinicopathological characteristics, conventional MRI findings, and quantitative synthetic parameters were assessed for all participants. Multivariable logistic regression analysis was performed to determine the potential independent imaging predictors for TNBC preoperatively. Receiver operating characteristic (ROC) curve analysis was used to evaluate the performance of these parameters.

RESULTS

A total of 231 participants with histopathological proven IDBC were included in this study (n=46 in the TNBC group and n=185 in the Non-TNBC group). The TNBC group had significantly larger tumour size (p=0.011) and more frequent intratumoural cystic or necrotic lesions (p<0.001) as compared to the Non-TNBC group. The univariate analysis showed that the TNBC tumours had significantly higher T1 (p=0.006) and T2 (p<0.001) values than Non-TNBC tumours. Subsequent multivariable analysis indicated that T2 values and the presence of cystic or necrotic lesions were the independent predictors for TNBC.

CONCLUSION

The T2 from synthetic imaging and the presence of cystic degeneration or necrosis within the breast cancer may serve as potential imaging biomarkers for preoperative differentiation of TNBC from Non-TNBC.

Immunoinformatics Prediction and Protective Efficacy of Vaccine Candidate PiuA-PlyD4 Against Streptococcus Pneumoniae

Purpose

This study was designed to evaluate the immune protective efficacy of the novel Streptococcus pneumoniae (S. pneumoniae) protein vaccine PiuA-PlyD4 through immunoinformatics prediction and in vitro and in vivo experiments.

Methods

In this study, we conducted immunoinformatics prediction and protection analysis on the fusion protein PiuA-PlyD4. The epitope composition of the vaccine was analyzed based on the prediction of B-cell and helper T-cell epitopes. Meanwhile, the molecular docking of PiuA and TLR2/4 was simulated. After immunizing C57BL/6 mice with the prepared vaccine, the biological safety, immunogenicity and conservation were evaluated. By constructing different infection models and from the aspects of adhesion inhibition and cytokines, the protective effect of the fusion protein vaccine PiuA-PlyD4 on S. pneumoniae infection was explored.

Results

PiuA-PlyD4 has abundant B-cell and helper T-cell epitopes and shows a high antigenicity score and structural stability. Molecular docking analysis suggested the potential interaction between PiuA and TLR2/4. The specific antibody titer of fusion protein antiserum was as high as (7.81±2.32) ×105. The protective effect of the immunized mice on nasal and lung colonization was significantly better than that of the control group, and the survival rate against S. pneumoniae infection of serotype 3 reached 50%. Cytokine detection showed that the humoral immune response, Th1, Th2 and Th17 cellular immune pathways were all involved in the process.

Conclusion

The study indicates that PiuA-PlyD4, whether the results are predicted by immunoinformatics or experimentally validated in vivo and in vitro, has good immunogenicity and immunoreactivity and can provide effective protection against S. pneumoniae infection. Therefore, it can be considered a promising prophylactic vaccine candidate for S. pneumoniae.

A Case Report of a Novel Isovaleryl-CoA Dehydrogenase Gene Mutation in a Chinese Family with Isovaleric Acidemia

BACKGROUND

Isovaleric acidemia (IVA) is a rare autosomal-recessive metabolic disorder caused by a genetic deficiency of isovaleryl-CoA dehydrogenase (IVD). Deficiency of IVD leads to the accumulation of organic acids; however, the genotype-phenotype relationship has not been well established.

METHODS

Two brothers with acute neonatal IVA in a Chinese family were reported, and their clinical manifestations and examination were described. MS/MS and GCMS were used to perform organic acid analysis of blood samples and urine samples, and the patient's blood was sequenced by NGS and Sanger sequencing of the ivd gene.

RESULTS

Sequence analysis of the ivd gene identified compound heterozygous mutations in the patient, the c.250T>C (p.W84R) missense mutation (novel) and the c.466-3_466-2 delCAinsGG splicing mutation, which were inherited from their parents. Various bioinformatics prediction algorithms suggest that the p.W84R missense mutation may destabilize the IVD monomer and reduce its ability to bind to substrates.

CONCLUSIONS

Both the clinical and genetic features of this family will help us to further expand the knowledge of IVA.

CEDAR: communication efficient distributed analysis for regressions

Electronic health records (EHRs) offer great promises for advancing precision medicine and, at the same time, present significant analytical challenges. Particularly, it is often the case that patient-level data in EHRs cannot be shared across institutions (data sources) due to government regulations and/or institutional policies. As a result, there are growing interests about distributed learning over multiple EHRs databases without sharing patient-level data. To tackle such challenges, we propose a novel communication efficient method that aggregates the optimal estimates of external sites, by turning the problem into a missing data problem. In addition, we propose incorporating posterior samples of remote sites, which can provide partial information on the missing quantities and improve efficiency of parameter estimates while having the differential privacy property and thus reducing the risk of information leaking. The proposed approach, without sharing the raw patient level data, allows for proper statistical inference. We provide theoretical investigation for the asymptotic properties of the proposed method for statistical inference as well as differential privacy, and evaluate its performance in simulations and real data analyses in comparison with several recently developed methods.

[The characteristics of gut microbiota in type 2 diabetes mellitus patients with hypertriglyceridemia]

Objective: To investigate the characteristics of gut microbiota in type 2 diabetes mellitus (T2DM) patients with hypertriglyceridemia (HTG). Methods: Eighty-one patients first diagnosed with T2DM were enrolled in the Third Xiangya Hospital of Central South University from January 2018 to December 2020, including 58 patients [46 males and 12 females, aged (43±13) years] with HTG [HTG group, triglyceride (TG)≥1.7 mmol/L]. There were 23 cases without HTG (NTG group), including 20 males and 3 females, aged (46±13) years. According to the severity of HTG, the patients of HTG group were divided into severe HTG group (STG group, TG ≥5.6 mmol/L) and mild HTG group (MTG group, 1.7 mmol/L≤TG<5.6 mmol/L). Thirty healthy controls were matched accordingly, including 21 males and 9 females, aged (45±6) years. Clinical laboratory indicators and feces of the subjects were collected and 16S rRNA sequencing was performed to compare the differences in intestinal flora among the groups. Results: The Shannon and Simpson indexes in HTG group were lower than those in NTG group and healthy control group (5.02±0.91 vs 5.45±0.55 and 5.60±0.63, P=0.003; 0.90±0.06 vs 0.93±0.04, 0.94±0.04, P=0.002). Compared with healthy control group and NTG group, the abundance of intestinal P_Proteobacteria, g_Escherichia_Shigella, s_Escherichia_Coli and g_Clostridium_sensu_stricto_1 increased in HTG group, while the abundance of p_Firmicutes, g_Faecalibacterium and Faecalibacterium_prausnitzii decreased. The abundance of g_Clostridium_sensu_stricto_1 in the STG group was higher than that of NTG and MTG groups, while the abundance of g_Faecalibacterium decreased. Spearman correlation analysis suggested that g_Clostridium_sensu_stricto_1 was positively correlated with glycosylated hemoglobin (r=0.22, P=0.044), fasting blood glucose (r=0.36, P=0.001), TG (r=0.27, P=0.015) and total cholesterol (r=0.44, P<0.001). Logistic regression analysis indicated that g_Faecalibacterium was a protective factor for T2DM with HTG(OR=0.90, 95%CI:0.83-0.97, P=0.006). Conclusions: The intestinal flora of T2DM patients with HTG was dysregulated, which was manifested as decreased diversity, increased abundance of P_Proteobacteria and decreased abundance of p_Firmicutes. g_Faecalibacterium is a protective factor for T2DM with HTG.

A candidate reference method and multiple commutable control materials for serum 25-hydroxyvitamin D measurement

OBJECTIVES

The aim of the current study was to establish a reliable candidate reference method for serum 25-hydroxyvitamin D [25(OH)D] measurement and to assess the commutability of multiple control materials among liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods.

METHODS

Serum 25-hydroxyvitamin D2 [25(OH)D2] and 25-hydroxyvitamin D3 [25(OH)D3] together with spiked internal standards were extracted with a one-step approach and then analyzed by LC-MS/MS. The commutability assessment for 25(OH)D was conducted according to the Clinical and Laboratory Standards Institute (CLSI) EP14-A3 protocol. 25(OH)D concentrations in 5 levels of unprocessed serum pools, 7 levels of serum pools spiked with 25(OH)D3 or 25(OH)D2, 3 levels of commercial control materials, 2 levels of spiked bovine serum, and 4 levels of external quality assessment (EQA) materials were measured along with 30 single-donor samples using the candidate reference method and two routine LC-MS/MS methods.

RESULTS

The candidate reference method could separate 25(OH)D2 and 25(OH)D3 from 14 potential interfering compounds completely within a 9-min analysis time. Good method precision was obtained, and measurement results on certified reference material NIST SRM 972a were within the uncertainty of the certified values. All candidate materials were assessed commutable for LC-MS/MS methods.

CONCLUSIONS

The candidate reference method for serum 25(OH)D measurement is precise, accurate, and robust against interferences and can provide an accuracy base for routine methods. The multiple alternative control materials with commutability among LC-MS/MS methods will facilitate the further standardization for serum 25(OH)D measurement.

[Clinical follow-up analysis of multidisciplinary treatment of children with spinal muscular atrophy]

Objective: To analyze the follow-up and clinical effect of multidisciplinary treatment on the children with spinal muscular atrophy (SMA). Methods: The clinical data including nutritional status, respiratory function, bone health and motor function of 45 children with SMA who received multidisciplinary management 1-year follow-up in the Children's Hospital, Zhejiang University School of Medicine from July 2019 to October 2021 were retrospectively collected. Comparisons before and after management were performed using paired-samples t-test or Wilcoxon rank-sum test, etc. Results: The age of 45 patients (25 boys and 20 girls) was 50.4 (33.6, 84.0) months at the enrollment, with 6 cases of type 1, 22 cases of type 2, and 17 cases of type 3 respectively. After the multidisciplinary management, the cases of SMA patients with malnutrition decreased from 22 to 12 (P=0.030), the level of vitamin D were significantly increased ((45±17) vs. (48±14) nmol/L, t=-4.13, P<0.001). There was no significant difference in the forced vital capacity %pred, the forced expiratory volume at 1 second %pred, and the peak expiratory flow %pred ((76±19)% and (76±21)%, (81±18)% and (79±18)%, (81±21)% and (78±17)%; t=-0.24, 1.36, 1.21; all P>0.05). The Cobbs angle of scoliosis also improved significantly (8.0°(0°, 13.0°) vs. 10.0°(0°, 18.5°), Z=-3.01, P=0.003). The Hammersmith functional motor scale expanded scores of children with SMA type 2 and type 3 both showed significant elevation (11.0 (8.0, 18.0) vs. 11.0 (5.0, 18.5) scores, 44.0 (36.5, 53.0) vs. 44.0 (34.0, 51.5) scores, Z=2.44, 3.11, P=0.015, 0.002). Conclusion: Multidisciplinary management is beneficial for delaying the progression of the multi-system impairments of SMA patients, such as malnutrition, restrictive ventilation dysfunction and scoliosis.

[Clinical follow-up analysis of nusinersen in the disease-modifying treatment of pediatric spinal muscular atrophy]

Objective: To explore the clinical efficacy of disease-modifying drug nusinersen on children with spinal muscular atrophy. Methods: The baseline and longitudinal clinical data of 15 children who were treated with nusinersen in the Children's Hospital, Zhejiang University School of Medicine from October 2019 to October 2021 were retrospectively collected. The general data (gender, age, genotype, and clinical classification, etc.), motor function, nutritional status, scoliosis and respiratory function were analyzed. Wilcoxon rank-sum test was used for comparing multi-system conditions before and after treatment. Results: The age of 15 cases (7 males, 8 females) was 6.8 (2.8, 8.3) years, with 2 cases of type 1, 6 cases of type 2, and 7 cases of type 3 respectively, and the course of disease was 55.0 (21.0, 69.0) months. After 9.0 (9.0, 24.0) months of treatment, the motor function scale evaluations of the Hammersmith neurological examination section 2 (13.0 (7.0, 23.0) vs. 18.0 (10.0, 25.0) scores, Z=-2.67, P=0.018) of 15 children, the Hammersmith functional motor scale expanded (38.0 (18.5, 45.5) vs. 42.0 (23.0, 51.0) scores, Z=-2.38, P=0.018), and the revised upper limb module (27.0 (19.5, 32.0) vs. 33.0 (22.5, 35.5) scores, Z=-2.52, P=0.012) of children with type 2 and 3 had significantly improved. Thirteen patients achieved clinically significant motor function improvement, and 2 of them had kept stable scale scores. Subjective reports also indicated that the muscle strength and daily exercise ability of these children improved after treatment, and no serious adverse reactions were reported. Supplemented by the multi-disciplinary team management, the levels of some indicators such as Cobbs angle of scoliosis and forced vital capacity all had significantly improved (all P<0.05). Conclusions: Nusinersen can improve the motor function of patients with 5q spinal muscular atrophy, which is also proved safe to be used in children. The drug treatment supplemented by the multi-disciplinary team management is helpful to improve the multi-system function of the children with spinal muscular atrophy.

The analysis of osteosarcopenia as a risk factor for fractures, mortality, and falls

Osteosarcopenia is defined as the concomitant occurrence of sarcopenia and osteoporosis/osteopenia. This study aimed to clarify whether osteosarcopenia implies a greater risk of fractures, mortality, and falls and to draw attention to osteosarcopenia.

INTRODUCTION

Osteosarcopenia, which is characterized by the co-existence of osteoporosis/osteopenia and sarcopenia, is one of the most challenging geriatric syndromes. However, the association between osteosarcopenia and the risk of falls, fractures, disability, and mortality is controversial.

METHODS

We searched PubMed, Embase, and the Cochrane Central Register of Controlled Trials, from their inception to March 18, 2021, for cohort studies on the relationship between osteosarcopenia and fractures, falls, and mortality. Two reviewers independently extracted data and assessed study quality. A pooled analysis was performed to calculate odds ratios (ORs) and 95% confidence intervals (CIs) using fixed or random-effects models.

RESULTS

Eight cohort studies including 19,836 participants showed that osteosarcopenia significantly increased the risk of fracture (OR 2.46, 95% CI 1.83-3.30, P_{heterogeneity} = 0.006, I² = 63.0%), three cohort studies involving 2601 participants indicated that osteosarcopenia significantly increased the risk of mortality (OR 1.66, 95% CI 1.23-2.26, P_{heterogeneity} = 0.214, I² = 35.2%), and three cohort studies involving 3144 participants indicated that osteosarcopenia significantly increased the risk of falls (OR 1.62, 95% CI 1.28-2.04, P_{heterogeneity} = 0.219, I² = 34.1%). No publication bias existed among the studies regarding the association between osteosarcopenia and fractures. The findings were robust according to the subgroup and sensitivity analyses.

CONCLUSIONS

This pooled analysis demonstrated that osteosarcopenia significantly increased the risk of fractures, falls, and mortality, thus highlighting its relevance in daily life. Therefore, we suggest that elderly persons should be aware of the risks associated with osteosarcopenia.

Measurement of serum 17-hydroxyprogesterone using isotope dilution liquid chromatography-tandem mass spectrometry candidate reference method and evaluation of the performance for three routine methods

OBJECTIVES

Accurate measurements of serum 17-hydroxyprogesterone (17OHP) are essential for diagnosis and treatment monitoring for congenital adrenal hyperplasia patients. The performance of serum 17OHP routine methods remains highly variable that calls for a candidate reference measurement procedure (cRMP) to improve the standardization of serum 17OHP measurements.

METHODS

Serum samples spiked with internal standards were extracted with a combination of solid-phase extraction and liquid-liquid extraction. The 17OHP was quantified by the isotope dilution coupled with liquid chromatography/tandem mass spectrometry (ID-LC/MS/MS) with electrospray ionization in positive ion mode. Nine structural analogs of 17OHP were evaluated for interferences. The precision and analytical recovery were assessed. Twenty native and 40 spiked serum for performance evaluation were measured by the cRMP and two clinical LC/MS routine methods.

RESULTS

No apparent interferences were found with the 17OHP measurement. The within-run, between-run, and total precision for our method were 0.4-0.8%, 0.6-2.0%, and 1.0-2.1% for four pooled serum (2.46-102.72 nmol/L), respectively. The recoveries of added 17OHP were 100.0-100.2%. For the performance of two LC/MS routine methods, they showed relative deviation ranges of -22.1 to 1.1% and -6.7 to 12.8%, respectively.

CONCLUSIONS

We developed and validated a reliable serum 17OHP method using ID-LC/MS/MS. The desirable accuracy and precision of this method enable it to serve as a promising cRMP to improve the standardization for serum 17OHP routine measurements.

Commutability Assessment of Candidate External Quality Assessment Materials for Aminotransferase Activity Measurements Based on Different Approaches in China

Background

Using commutable external quality assessment (EQA) materials is important for monitoring successful harmonization efforts. We assessed the commutability of four human serum pool (HSP) preparations to identify candidate EQA materials for alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activity measurement.

Methods

One set each of 85 clinical samples (CSs) was collected for ALT and AST activity measurement. The 15 candidate EQA materials included four types of HSP preparations (A to D): materials A, C, and D contained human original recombinant (HOR) aminotransferases; materials B was mixed leftover samples. The CSs and 15 candidate EQA materials were analyzed using seven routine assays, and the ln-transformed results were analyzed in 21 assay pairs. Commutability was assessed using Deming regression, with a 95% prediction interval (CLSI approach) and the difference in bias with an error component model (International Federation of Clinical Chemistry and Laboratory Medicine [IFCC] approach).

Results

For ALT, all materials were commutable for 14–21 assay pairs according to the CLSI and IFCC approaches. For AST, B01–03 showed commutability for 14–21 assay pairs, and C01–03 and D01–03 showed commutability for no less than 10 assay pairs according to the two approaches. A01–06 were commutable for 9–16 assay pairs according to the CLSI approach, but for 6–9 assay pairs according to the IFCC approach.

Conclusions

Mixed leftover samples showed desirable commutability characteristics as candidate EQA materials for routine aminotransferase activity measurements. Human serum bases supplemented with HOR were commutable for most routine ALT activity measurements.

[The fundus autofluorescence of retinal astrocytic hamartomas in tuberous sclerosis complex]

Objective: To investigate the autofluorescence findings of retinal astrocytic hamartoma (RAH) in patients with tuberous sclerosis complex (TSC). Methods: It was a retrospective case series study. Twenty-three patients (35 eyes) who were referred to Department of Internal Medicine and Department of Ophthalmology, Peking Union Medical College Hospital between November 2012 and June 2018 with established TSC-associated RAH diagnosis were included. The findings of fundus autofluorescence, fundus photos and spectral-domain optical coherence tomography (SD-OCT) were retrospectively reviewed. RAH lesions were classified into three types based on the morphology shown in fundus photos. The fundus autofluorescence features of TSC-associated RAH were described. The Welch's test and Fisher's exact test were used for statistical analysis. Results: The patients were 8 males and 15 females aged (28±9) years old (range, 15-55 years). Seventy-two RAH lesions were examined, including 59 type 1 RAHs, 7 type 2 RAHs and 6 type 3 RAHs. According to fundus autofluorescence, type 1 RAHs could be further divided into reduced, speckled and background autofluorescence patterns, among which the hypoautofluorescence pattern accounted for the majority (69.5%, 41/59), while the speckled pattern was usually accompanied by outer retinal disorganization and discontinuation of photoreceptor outer segment as revealed by SD-OCT. No significant difference was revealed in tumor thickness for reduced, speckled and background autofluorescence patterns of type 1 RAHs [(490.2±97.9) vs. (589.2±221.6) vs. (463.0±76.2) μm respectively, F=1.426, P=0.283]. Among type 1 RAHs, the number of reduced autofluorescence pattern lesions found in perifoveal, peripapillary, inferonasal, inferotemporal, superonasal, superotemporal quadrants were 9, 4, 4, 7, 4, 13 respectively, while that of speckled autofluorescence pattern lesions were 3, 0, 3, 2, 3, 2 and background autoflurorescence pattern lesions 3, 0, 1, 1, 0, 0. No significant difference was revealed in location distribution (P=0.452) either. Type 2 RAHs featured numerous hyperautofluorescent spots or plaques, and calcification in type 2 RAHs varied in autofluorescence intensity. Type 3 RAHs, combining the features of type 1 and 2 RAHs, were characterized by central hyperautofluorescent spots and hypoautoflurescent rim, but the area of hyperautofluorescence was smaller than that of calcification as shown in fundus photos. Conclusions: In TSC, the fundus autofluorescence of RAHs varies from hypoautofluorescence to hyperautofluorescence patterns according to RAH types. The retinal involvement and calcification degree of TSC-associated RAHs could be reflected on the autofluorescence, which was beneficial to the full assessment. (Chin J Ophthalmol, 2020, 56: 211-216).

Retinopathy develops at similar glucose levels but higher HbA1c levels in people with black African ancestry compared to white European ancestry: evidence for the need to individualize HbA1c interpretation

AIMS

To examine the association of HbA_1c and glucose levels with incident diabetic retinopathy according to black African or white European ancestry.

METHODS

In this retrospective cohort study of 202 500 US Veterans with diabetes (2000-2014), measures included HbA_1c , outpatient random serum/plasma glucose, and incident retinopathy [conversion from negative to ≥2 positive evaluations (ICD-9 codes), without a subsequent negative].

RESULTS

At baseline, the study population had a mean age of 59.3 years, their mean BMI was 31.9 kg/m² , HbA_1c level was 57 mmol/mol (7.4%) and glucose level was 8.8 mmol/l, and 77% were of white European ancestry (white individuals) and 21% of black African ancestry (black individuals). HbA_1c was 0.3% higher in black vs white individuals (P < 0.001), adjusting for baseline age, sex, BMI, estimated glomerular filtration rate (eGFR), haemoglobin, and average systolic blood pressure and glucose. Over 11 years, incident retinopathy occurred in 9% of black and 7% of white individuals, but black individuals had higher HbA_1c , glucose, and systolic blood pressure (all P < 0.001); adjusted for these factors, incident retinopathy was reduced in black vs white individuals (P < 0.001). The population incidence of retinopathy (7%) was associated with higher mean baseline HbA_1c in individuals with black vs white ancestry [63 mmol/mol (7.9%) vs 58 mmol/mol (7.5%); P < 0.001)], but with similar baseline glucose levels (9.0 vs 9.0 mmol/l; P = 0.660, all adjusted for baseline age, sex and BMI).

CONCLUSIONS

Since retinopathy occurs at higher HbA_1c levels in black people for a given level of average plasma glucose, strategies may be needed to individualize the interpretation of HbA_1c measurements.

Commutability of external quality assessment materials for serum magnesium and calcium measurements

The commutability of pooled patient sera (PPS) and control materials (CM) should be evaluated to investigate their suitability for use in an external quality assessment (EQA) program. Individual human samples, PPS and CM were analyzed by four routine methods and inductively coupled plasma mass spectrometry reference methods for magnesium and calcium measurements. The commutability was analyzed according to EP14-A3 protocol and the difference in bias approach, respectively. For magnesium measurements, all PPS were commutable and 3/5 CM were commutable for all measurement systems according to the EP14-A3 protocol. For calcium measurements, most PPS were commutable for all measurement systems, but the CM were only commutable with the Cobas c702 system. The IFCC approach produced similar commutability profiles, except that a large number of inconclusive results appeared. The routine methods exhibited excellent linearity and precision. The majority of relative biases between the routine and reference methods were beyond the bias limits. The commutability of the CM and PPS vary depending on which evaluation approach and criterion is applied. Superiority in the commutability of PPS over CM was observed whichever evaluation approach is applied.

[The association between blood pressure variability and sleep stability in essential hypertensive patients with sleep disorder]

Objective: To investigate the association of blood pressure variability and sleep stability in essential hypertensive patients with sleep disorder by cardiopulmonary coupling. Methods: Performed according to strict inclusion and exclusion criteria, 88 new cases of essential hypertension who came from the international department and the cardiology department of china-japan friendship hospital were enrolled. Sleep stability and 24 h ambulatory blood pressure data were collected by the portable sleep monitor based on cardiopulmonary coupling technique and 24 h ambulatory blood pressure monitor. Analysis the correlation of blood pressure variability and sleep stability. Results: In the nighttime, systolic blood pressure standard deviation, systolic blood pressure variation coefficient, the ratio of the systolic blood pressure minimum to the maximum, diastolic blood pressure standard deviation, diastolic blood pressure variation coefficient were positively correlated with unstable sleep duration (r=0.185, 0.24, 0.237, 0.43, 0.276, P<0.05). Conclusions: Blood pressure variability is associated with sleep stability, especially at night, the longer the unstable sleep duration, the greater the variability in night blood pressure.

Glucose challenge test screening for prediabetes and early diabetes

AIMS

To test the hypothesis that a 50-g oral glucose challenge test with 1-h glucose measurement would have superior performance compared with other opportunistic screening methods.

METHODS

In this prospective study in a Veterans Health Administration primary care clinic, the following test performances, measured by area under receiver-operating characteristic curves, were compared: 50-g oral glucose challenge test; random glucose; and HbA_1c level, using a 75-g oral glucose tolerance test as the 'gold standard'.

RESULTS

The study population was comprised of 1535 people (mean age 56 years, BMI 30.3 kg/m² , 94% men, 74% black). By oral glucose tolerance test criteria, diabetes was present in 10% and high-risk prediabetes was present in 22% of participants. The plasma glucose challenge test provided area under receiver-operating characteristic curves of 0.85 (95% CI 0.78-0.91) to detect diabetes and 0.76 (95% CI 0.72-0.80) to detect high-risk dysglycaemia (diabetes or high-risk prediabetes), while area under receiver-operating characteristic curves for the capillary glucose challenge test were 0.82 (95% CI 0.75-0.89) and 0.73 (95% CI 0.69-0.77) for diabetes and high-risk dysglycaemia, respectively. Random glucose performed less well [plasma: 0.76 (95% CI 0.69-0.82) and 0.66 (95% CI 0.62-0.71), respectively; capillary: 0.72 (95% CI 0.65-0.80) and 0.64 (95% CI 0.59-0.68), respectively], and HbA_1c performed even less well [0.67 (95% CI 0.57-0.76) and 0.63 (95% CI 0.58-0.68), respectively]. The cost of identifying one case of high-risk dysglycaemia with a plasma glucose challenge test would be $42 from a Veterans Health Administration perspective, and $55 from a US Medicare perspective.

CONCLUSIONS

Glucose challenge test screening, followed, if abnormal, by an oral glucose tolerance test, would be convenient and more accurate than other opportunistic tests. Use of glucose challenge test screening could improve management by permitting earlier therapy.

[Association between interleukin-18 gene polymorphisms and hepatocellular carcinoma caused by hepatitis B virus]

OBJECTIVE

To investigate the association between the single nucleotide polymorphisms (SNPs) IL-18-137G/C (rs187238) and IL-18-607A/C (rs1946518) in interleukin-18 (IL-18) gene and hepatocellular carcinoma (HCC) caused by the hepatitis B virus (HBV).

METHODS

The subjects were divided into HBV-related HCC group (109 patients), chronic HBV infection group (113 patients), and healthy control group (127 patients). The polymerase chain reaction-ligase detection reaction (PCR-LDR) was used to determine the alleles and genotypes of the two SNPs IL-18-137G/C and IL-18-607A/C. The t-test and chi-square test were used for baseline data. The chi-square test was used to investigate the differences in genotype and allele frequencies across the three groups. Non-conditional logistic regression analysis was used to compare the odds ratios (ORs) and 95% confidence intervals (CIs) for different genotypes/alleles in predicting the risk of HBV-related HCC.

RESULTS

The HBV-related HCC group showed significantly higher AA genotype and A allele frequencies of the SNP IL-18-607A/C than the healthy control group (AA genotype frequency: 29.4% vs 18.1%, χ (2) = 4.152, P < 0.05; A allele frequency: 54.6% vs 44.1%, 5.169, P < 0.05), which were positively correlated with the risk of HBV-related HCC (AA genotype frequency: OR = 1.879, 95% CI: 1.020-3.464; A allele frequency: OR = 1.524, 95% CI: 1.059-2.193). The chronic HBV infection group had a significantly higher A allele frequency of the SNP IL-18-607A/C than the healthy control group (54.0% vs 44.1%, χ (2) = 4.680, P < 0.05), which was positively correlated with the risk of chronic HBV infection (OR = 1.487, 95% CI: 1.037-2.132). The genotype and allele frequencies of the SNP IL-18-607A/C showed no significant differences between the HBV-related HCC group and the chronic HBV infection group (P > 0.05). The genotype and allele frequencies of the SNP IL-18-137G/C showed no significant differences between any two groups of the three groups (P > 0.05).

CONCLUSION

The AA genotype and A allele frequencies of the SNP IL-18-607A/C are positively correlated with the morbidity of HBV-related HCC, and the A allele frequency of the SNP IL-18-607A/C is positively correlated with the morbidity of chronic HBV infection.

[In vivo confocal microscopic observation of corneal changes in patients with chronic Stevens-Johnson syndrome or toxic epidermal necrolysis]

Objective: To describe corneal alterations visible on in vivo confocal microscopy in patients with debilitating ocular sequelae caused by Stevens-Johnson syndrome (SJS) or toxic epidermal necrolysis (TEN). Methods: Twenty-two eyes of 11 consecutive patients suffering from chronic SJS or TEN were studied using slit lamp and in vivo confocal microscopy in the Ophthalmology Outpatient Department of Peking Union Medical College Hospital from March 2014 to April 2015. Results: Dry eye with meibomian gland dysfunction (19 eyes of 10 patients, 86.4%) was the most frequent clinical sequelae. Two patients (3 eyes, 13.6%) had severe vison loss with corneal neovascularization and conjunctivization. One patient had asymmetric binocular disease. Corneal epithelial cells were observed at an active state in 10 patients (19 eyes, 86.4%) and corneal stromal cells at an active state in all patients (22 eyes, 100%). Twenty eyes (10 patients, 91%) were noted with abnormal nerve layout and 10 eyes (5 patients, 45.5%) with dendritic cell infiltration around pathological nerve damages. Numerous inflammory cells were observed in 6 eyes (3 patients, 27.3%). Conclusions: The corneas of patients with chronic ocular sequelae associated with SJS or TEN present a number of abnormalities. In vivo confocal microscopy is a potetial useful tool for therapeutic indications and for follow-up of the debilitating chronic ocular problems linked to SJS and TEN. (Chin J Ophthalmol, 2017, 53:177-181).

[Research advances in necessity of antiviral therapy for chronic hepatitis B virus carriers]

Chronic hepatitis B virus (HBV) carriers are facing the risk of progression to liver fibrosis, liver cirrhosis, and hepatocellular carcinoma. However, due to low risk, slow disease progression, and unsatisfactory short-term effect of antiviral treatment, controversy still exists over whether such patients should be given antiviral treatment. This article reviews the research advances in the necessity and feasibility of antiviral therapy for chronic hepatitis B virus carriers, so as to provide a reference for clinical practice.

Treatment of Type 2 diabetes mellitus in Chongqing of China: unaffordable care for the poor

AIM

This study aims to investigate the medical expenditure of people with Type 2 diabetes mellitus in Chongqing, China; to explore factors that contribute to the expenditure; and to examine the financial burden placed on households, particularly poor households.

METHODS

A cross sectional survey was conducted with a sample of people diagnosed with Type 2 diabetes mellitus in 2014. Of the 664 people eligible, 76% were interviewed. Descriptive statistics and log-linear regression were used to examine respondents' age, sex and level education, location of residence, income and type of health insurance associated with out-of-pocket expenditure on accessing diabetes mellitus care.

RESULTS

In a year, average out-of-pocket expenditure on the purchase of drugs from pharmacies and having outpatient care were US $333 and US $310, respectively. The average out-of-pocket expenditure on accessing inpatient care was 3.7 times (US $1159) that of accessing outpatient care. After adjusting for age and sex, out-of-pocket expenditure on diabetes care was significantly higher for people covered by the Urban Employee Basic Medical Insurance programme and those enrolled in the identified priority diseases reimbursement programme, which provided higher reimbursement rates for outpatient and (or) inpatient care. Out-of-pocket expenditures on the purchase of drugs from pharmacies, having outpatient and inpatient care, respectively, were 9.8%, 16.2% and 62.6% of annual household income in low-income group.

CONCLUSION

Even with health insurance coverage, poor people with Type 2 diabetes mellitus suffered from significant financial hardship. This has significant implications for models of care and healthcare financing in China with the growing burden of diabetes.

Clinical practice patterns on the use of magnesium sulphate for treatment of pre-eclampsia and eclampsia: a multi-country survey

Objective

To characterise the current clinical practice patterns regarding the use of magnesium sulphate (MgSO₄) for eclampsia prevention and treatment in a multi‐country network of health facilities and compare with international recommendations.

Design

Cross‐sectional survey.

Setting

A total of 147 health facilities in 15 countries across Africa, Latin America and Asia.

Population

Heads of obstetric departments or maternity units.

Methods

Anonymous online and paper‐based survey conducted in 2015.

Main outcome measures

Availability and use of MgSO₄; availability of a formal clinical protocol for MgSO₄ administration; and MgSO₄ dosing regimens for eclampsia prevention and treatment.

Results

Magnesium sulphate and a formal protocol for its administration were reported to be always available in 87.4% and 86.4% of all facilities, respectively. MgSO₄ was used for the treatment of mild pre‐eclampsia, severe pre‐eclampsia and eclampsia in 24.3%, 93.5% and 96.4% of all facilities, respectively. Regarding the treatment of severe pre‐eclampsia, 26.4% and 7.0% of all facilities reported using dosing regimens that were consistent with Zuspan and Pritchard regimens, respectively. Across regions, intramuscular maintenance regimens were more commonly used in the African region (45.7%) than in the Latin American (3.0%) and Asian (22.9%) regions, whereas intravenous maintenance regimens were more often used in the Latin American (94.0%) and Asian (60.0%) regions than in the African region (21.7%). Similar patterns were found for the treatment of eclampsia across regions.

Conclusions

The reported clinical use of MgSO₄ for eclampsia prevention and treatment varied widely, and was largely inconsistent with current international recommendations.

Tweetable abstract

MgSO₄ regimens for eclampsia prevention and treatment in many hospitals are inconsistent with international recommendations.

MgSO₄ regimens for eclampsia prevention and treatment in many hospitals are inconsistent with international recommendations.

[Recent progress in research of pathogeneses of Stevens-Johnson syndrome and toxic epidermal necrolysis]

Stevens-Johnson syndrome(SJS)and toxic epidermal necrolysis(TEN)are life-threatening cutaneous adverse drug reactions that induce widespread epidermal necrosis. Ocular and cutaneous diseases are common chronic sequelae of SJS and TEN. Several concepts have been proposed to explain the pathogenesis of severe cutaneous adverse drug reactions. Recent advances in genetic, pharmacogenomics and immunologic studies have provided evidences of genetic predispositions, drug metabolism and cytokines related to SJS and TEN. With regard to keratinocyte death, several cell death mediators, such as Fas/FasL, granulysin and TNF, have been proposed to play an important role in the pathogeneses of SJS and TEN. A subset of T lymphocytes, including regulatory T cells, may also play a role. This review summarizes the pathogeneses of SJS and TEN mainly from the aspects of genetic susceptibilities, drug metabolism, and immune cells and cytokines. (Chin J Ophthalmol, 2016, 52: 708-713).

[Relationship between sleep architecture and blood pressure dynamic change in patients with sleep apnea syndrome]

OBJECTIVE

To investigate sleep architecture and blood pressure dynamic change in patients with Sleep apnea syndrome by electrocardiogram-based cardiopulmonary coupling analysis system.

METHODS

Seventy-nine sleep disorder participants (PSQI≥8) were enrolled. Electrocardiogram-based cardiopulmonary coupling analysis device and ambulatory blood pressure monitoring were synchronously used to evaluate sleep architecture and blood pressure circadian rhythm. The patients were divided into SAS group (47 participants) and non-SAS group (32 participants) according to the Apnea Hypopnea Index (AHI) that calculated by CPC device. The data of sleep architecture and blood pressure variability were compared between two groups.

RESULTS

Compared with non-SAS group, SAS group have less proportion of deep sleep, more proportion of light sleep, higher mean blood pressure in 24 hours and daytime, lower nocturnal blood pressure dipping, faster mean heart rate in night time (P<0.05). AHI has moderate inverse correlation with deep sleep time, wake/dream time (-0.6≤r<-0.3), moderate positive correlation with light sleep time (0.3<r≤0.6), high inverse correlation with nocturnal blood pressure dipping (r=-0.785, P=0.000), moderate positive correlation with mean diastolic blood pressure (r=0.425, P=0.019).

CONCLUSION

Our study shows that less proportion of deep sleep, more proportion of light sleep, 24 hours mean blood pressure and nocturnal blood pressure increase in the patients with Sleep Apnea Syndrome. The severity of Sleep Apnea Syndrome has a positive correlation with the severity of abnormal sleep architecture and the degree of blood pressure elevation.

[Analysis on the total allergens of phoenix roebelenii pollen with two dimensional electrophoresis followed by immunoblotting]

Objective:To investigate allergen extract and to seek the main allergens of phoenix roebelenii pollen by the technology of two dimensional electrophoresis(2-DE)in protein analysis and immunoblotting.Method:Phoenix roebelenii pollen allergen extract was prepared with routine method, 2-DE combined with immunoblotting assay(Western Blotting),laser imagescanning, 2-DE gel analysis software were used to analyzing its protein components.Result:About 601 soluble proteins spots were revealed in coomassie stained gels.Most of the proteins had a molecular weight (Mr) of 20 to 130 kD, and an isoelectric point(pI) value of 4.0 to 8.0. Immunoblotting of 2-DE were showed and there were 19 specific antigen spots, compared with the controls.Conclusion:2-DE is a good method in protein analysis of ephemeroptera allergen extract, and it is useful in seeking main allergens and further research for allergic components.

Social networks and health-related quality of life among Chinese old adults in urban areas: results from 4th National Household Health Survey

OBJECTIVE

To examine the associations between components of social networks and health-related quality of life (HRQoL) in community-dwelling old adults in urban areas in China.

STUDY DESIGN

Data from the 4th National Household Health Survey (NHHS) in China, conducted in 2008, were used. HRQoL of respondents aged ≥15 years was assessed using EQ-5D in the NHHS.

METHODS

The sample for the current analysis included 9833 old adults aged ≥60 years. Multiple linear and logistic regression models were used to assess the associations between indicators of social network and HRQoL.

RESULTS

Approximately 6% of the respondents saw their children once a year or less, and approximately 1% reported that they had no children. Thirteen percent of the sample seldom contacted their neighbours and seldom met with relatives or friends; approximately 62% seldom attended social gatherings. The five dimensions of HRQoL (mobility, self-care, usual activities, pain/discomfort and anxiety/depression) were reported to be moderate or severe in 14.5%, 9.4%, 12.6%, 18.3% and 9.3% of the sample, respectively. The mean visual analogue scale (VAS) score and EQ-5D index using the time trade-off method was 70.96 [standard deviation (SD) 14.79] and 0.869 (SD 0.163), respectively. After adjusting for potential confounding variables, old adults with weaker social networks were more likely to report problems on EQ-5D dimensions, lower VAS scores and lower EQ-5D indexes.

CONCLUSIONS

For old adults living in urban communities in China, increased social participation has a positive effect on various dimensions of HRQoL. There is a need for policy considerations that will improve integration of community-level public resources in order to encourage frequent social interaction among old adults, and promote health and social care as a whole.

Clinical pharmacokinetic properties of magnesium sulphate in women with pre-eclampsia and eclampsia

BACKGROUND

The pharmacokinetic basis of magnesium sulphate (MgSO4 ) dosing regimens for eclampsia prophylaxis and treatment is not clearly established.

OBJECTIVES

To review available data on clinical pharmacokinetic properties of MgSO4 when used for women with pre-eclampsia and/or eclampsia.

SEARCH STRATEGY

MEDLINE, EMBASE, CINAHL, POPLINE, Global Health Library and reference lists of eligible studies.

SELECTION CRITERIA

All study types investigating pharmacokinetic properties of MgSO4 in women with pre-eclampsia and/or eclampsia.

DATA COLLECTION AND ANALYSIS

Two authors extracted data on basic pharmacokinetic parameters reflecting the different aspects of absorption, bioavailability, distribution and excretion of MgSO4 according to identified dosing regimens.

MAIN RESULTS

Twenty-eight studies investigating pharmacokinetic properties of 17 MgSO4 regimens met our inclusion criteria. Most women (91.5%) in the studies had pre-eclampsia. Baseline serum magnesium concentrations were consistently <1 mmol/l across studies. Intravenous loading dose between 4 and 6 g was associated with a doubling of this baseline concentration half an hour after injection. Maintenance infusion of 1 g/hour consistently produced concentrations well below 2 mmol/l, whereas maintenance infusion at 2 g/hour and the Pritchard intramuscular regimen had higher but inconsistent probability of producing concentrations between 2 and 3 mmol/l. Volume of distribution of magnesium varied (13.65-49.00 l) but the plasma clearance was fairly similar (4.28-5.00 l/hour) across populations.

CONCLUSION

The profiles of Zuspan and Pritchard regimens indicate that the minimum effective serum magnesium concentration for eclampsia prophylaxis is lower than the generally accepted level. Exposure-response studies to identify effective alternative dosing regimens should target concentrations achievable by these standard regimens.

TWEETABLE ABSTRACT

Minimum effective serum magnesium concentration for eclampsia prophylaxis is lower than the generally accepted therapeutic level.

Resistance and integron characterization of Acinetobacter baumannii in a teaching hospital in Chongqing, China

A total of 189 Acinetobacter baumannii isolates were collected in 2011 from a teaching hospital in Chongqing, China. Susceptibility data showed strains carrying integrons were significantly more resistant to all tested antibiotics that strains lacking integrons. Five types of gene cassettes belonging to class I integrons were identified in this study, and for the first time two types of gene cassettes belonging to class II integrons are reported. Most of the cassettes belong to a class I integron (136/144) encoding arr3, aacA4, dfrA17, aadA5, aadB, cat, blaOXA10 , aadA1, aadA2, dfrA and aacC1. Isolates contained a class I gene cassette; AadA2-HP-dfrA was the prevalent strain in this hospital. A class II integron was detected in eight strains, which contained the type IV fimbriae expression regulatory gene pilR and sulfate adenylyltransferase, suggesting a possible role in multidrug resistance. The major epidemic strains from intensive care unit patients belong to international clone 2. In conclusion, the presence of integrons was significantly associated with multiple drug resistance of A. baumannii in this hospital, and class I integron isolates bearing AadA2-HP-dfrA were the prevalent strain in this hospital.

Aging is associated with increased HbA1c levels, independently of glucose levels and insulin resistance, and also with decreased HbA1c diagnostic specificity

AIM

To determine whether using HbA1c for screening and management could be confounded by age differences, whether age effects can be explained by unrecognized diabetes and prediabetes, insulin resistance or postprandial hyperglycaemia, and whether the effects of aging have an impact on diagnostic accuracy.

METHODS

We conducted a cross-sectional analysis in adults without known diabetes in the Screening for Impaired Glucose Tolerance (SIGT) study 2005-2008 (n=1573) and the National Health and Nutrition Examination Survey (NHANES) 2005-2006 (n=1184).

RESULTS

Both glucose intolerance and HbA(1c) levels increased with age. In univariate analyses including all subjects, HbA(1c) levels increased by 0.93 mmol/mol (0.085%) per 10 years of age in the SIGT study and by 1.03 mmol/mol (0.094%) per 10 years in the NHANES; in both datasets, the HbA(1c) increase was 0.87 mmol/mol (0.08%) per 10 years in subjects without diabetes, and 0.76 mmol/mol (0.07%) per 10 years in subjects with normal glucose tolerance, all P<0.001. In multivariate analyses of subjects with normal glucose tolerance, the relationship between age and HbA(1c) remained significant (P<0.001) after adjustment for covariates including race, BMI, waist circumference, sagittal abdominal diameter, triglyceride/HDL ratio, and fasting and 2-h plasma glucose and other glucose levels, as assessed by an oral glucose tolerance test. In both datasets, the HbA(1c) of an 80-year-old individual with normal glucose tolerance would be 3.82 mmol/mol (0.35%) greater than that of a 30-year-old with normal glucose tolerance, a difference that is clinically significant. Moreover, the specificity of HbA(1c) -based diagnostic criteria for prediabetes decreased substantially with increasing age (P<0.0001).

CONCLUSIONS

In two large datasets, using different methods to measure HbA(1c), the association of age with higher HbA(1c) levels: was consistent and similar; was both statistically and clinically significant; was unexplained by features of aging; and reduced diagnostic specificity. Age should be taken into consideration when using HbA(1c) for the diagnosis and management of diabetes and prediabetes.

Stress analysis of carotid atheroma in a transient ischaemic attack patient using the MRI-based fluid-structure interaction method

Rupture of atherosclerotic plaque is a major cause of mortality. Plaque stress analysis, based on patient-specific multisequence in vivo MRI, can provide critical information for the understanding of plaque rupture and could eventually lead to plaque rupture prediction. However, the direct link between stress and plaque rupture is not fully understood. In the present study, the plaque from a patient who recently experienced a transient ischaemic attack (TIA) was studied using a fluid-structure interaction method to quantify stress distribution in the plaque region based on in vivo MR images. The results showed that wall shear stress is generally low in the artery with a slight increase at the plaque throat owing to minor luminal narrowing. The oscillatory shear index is much higher in the proximal part of the plaque. Both local wall stress concentrations and the relative stress variation distribution during a cardiac cycle indicate that the actual plaque rupture site is collocated with the highest rupture risk region in the studied patient.

Subject-specific computational simulation of left ventricular flow based on magnetic resonance imaging

A detailed investigation of left ventricle (LV) flow patterns could improve our understanding of the function of the heart and provide further insight into the mechanisms of heart failure. This study presents patient-specific modelling with magnetic resonance imaging (MRI) to investigate LV blood flow patterns in normal subjects. In the study, the prescribed LV wall movements based on the MRI measurements drove the blood flow in and out of the LV in computational fluid dynamics simulation. For the six subjects studied, the simulated LV flow swirls towards the aortic valve and is ejected into the ascending aorta with a vertical flow pattern that follows the left-hand rule. In diastole, the inflow adopts a reasonably straight route (with no significant secondary flow) towards the apex in the rapid filling phase with slight variations in the jet direction between different cases. When the jet reaches about two thirds of the distance from the inflow plane to the apex, the blood flow starts to change direction and swirls towards the apex. In the more slowly filling phase, a centrally located jet is evident with vortices located on both sides of the jet on an anterior—posterior plane that passes through the mitral and aortic valves. In the inferior—superior plane, a main vortex appears for most of the cases in which an anticlockwise vortex appears for three cases and a clockwise vortex occurs for one case. The simulated flow patterns agree well qualitatively with MRI-measured flow fields.

Wave dissipation in flexible tubes in the time domain: In vitro model of arterial waves

Earlier work of wave dissipation in flexible tubes and arteries has been carried out predominantly in the frequency domain and most of the studies used the measured pressure waveform for presenting the results. In this work we investigate the pattern of wave dissipation in the time domain using the separated forward and backward travelling waves in flexible tubes. We tested four sizes of latex tubes of 2m in length each, where a single semi-sinusoidal in shape, pressure wave, was produced at the inlet of each tube. Simultaneous measurements of pressure and flow waveforms were recorded every 5cm along the tubes and wave speed was determined using the pressure-velocity loop method (PU-loop). The measured data and wave speed were used to separate the pressure waveform and wave intensity, into their forward and backward directions, using wave intensity analysis (WIA). Also, the energy carried by the wave was calculated by integrating the relevant area under the wave intensity curve. The peak of the measured pressure waveform increased downstream, however, the peak of the separated forward pressure waveform decreased exponentially along the tube. Wave intensity and energy also dissipated exponentially along the travelling distance. The peaks of the separated pressure and wave intensity decreased in the forward in a similar exponential way to that in the backward direction in all four tube sizes. Also, the smaller the size of the tube the greater wave dissipation it caused. We conclude that wave separation is useful in studying wave dissipation in elastic tubes, and WIA provides a convenient method for determining the dissipation of the energy carried by the wave along the travelled distance. The separated pressure waveform, wave intensity and wave energy dissipate exponentially with the travelling distance, and wave dissipation varies conversely with the diameter of elastic tubes.

The influence of inflow boundary conditions on intra left ventricle flow predictions

The combination of computational fluid dynamics (CFD) and magnetic resonance imaging (MRI) offers a promising tool that enables the prediction of blood flow patterns in subject-specific cardiovascular models. The influence of the model geometry on the accuracy of the simulation is well recognized. This paper addresses the impact of different boundary conditions on subject-specific simulations of left ventricular (LV) flow. A novel hybrid method for prescribing effective inflow boundary conditions in the mitral valve plane has been developed. The detailed quantitative results highlight the strengths as well as the potential pitfalls of the approach.

Comparative study of magnetic resonance imaging and image-based computational fluid dynamics for quantification of pulsatile flow in a carotid bifurcation phantom

A combined magnetic resonance imaging (MRI) and computational fluid dynamics (CFD) modeling study was carried out for pulsatile flow in a carotid bifurcation phantom. The aim of the study was to quantify differences in flow patterns between MRI measurement and MRI-based CFD simulations and to further explore the potential for in vivo applications. The computational model was reconstructed from high resolution magnetic resonance (MR) scans. Velocities derived from phase-contrast MR measurements were used as boundary conditions for the CFD calculation. Detailed comparisons of velocity patterns were made between the CFD results and MRI measurements. Good agreement was achieved for the main velocity component in both well-behaved flow (in the common carotid) and disturbed region (in the carotid sinus). Comparison of in-plane velocity vectors showed less satisfactory consistency and revealed that the MR measurements obtained were inadequate to depict the secondary flow pattern as expected. It can be concluded that the combined MRI/CFD is expected to provide more reliable information about the full three-dimensional velocity field.

Reproducibility study of 3D geometrical reconstruction of the human carotid bifurcation from magnetic resonance images

The combined magnetic resonance imaging (MRI) and computational fluid dynamics (CFD) modeling approach is playing an increasingly important role in advancing our understanding of the relationship between hemodynamics and arterial disease. Nevertheless, such a modeling approach involves a number of uncertainties associated with various stages of the process. The present study is concerned with the reproducibility of geometry reconstruction, one of the most crucial steps in the modeling process. The reproducibility test was conducted on the right carotid bifurcation of eight normal human subjects, each of whom were scanned twice using the same MR protocol with an in-plane resolution of 0.625 mm. Models constructed from different scans of the same subject were compared and assessed using four quantitative measures: centerline distance, cross-sectional area, contour shape factors, and mean radius difference. The difference in the maximum carotid bulb area between the two scans was found to be <8.1% for all subjects. Shape factors (measuring the dissimilarity between two contours) of <10% were achieved in most of the common carotid arteries (CCAs) and internal carotid arteries (ICAs). The mean radius difference between the two scans was <0.4 mm for all subjects. Among the three vessels, the geometry of CCA was well reproduced by the reconstruction procedure in most of the cases, while the external carotid artery (ECA) showed the worst reproducibility. The impact of geometrical differences on CFD-predicted flow patterns and wall shear stress (WSS) will be investigated and discussed in a separate paper.

Reproducibility study of magnetic resonance image-based computational fluid dynamics prediction of carotid bifurcation flow

The importance of shear stress in the initiation and progression of atherosclerosis has been recognized for some time. A novel way to quantify wall shear stress under physiologically realistic conditions is to combine magnetic resonance imaging (MRI) and computational fluid dynamics. The present study aims to investigate the reproducibility of the simulated flow by using this combined approach. The right carotid bifurcations of eight healthy subjects were scanned twice with MRI within a few weeks. Three-dimensional geometries of the vessels were reconstructed for each scan and each subject. Pulsatile flows through these models were calculated to assess errors associated with the predicted flow parameters. This was done by comparing various wall shear stress indices, including the time-averaged wall shear stress (WSS), oscillating shear index (OSI), WSS Gradients (WSSG) and WSS Angle Deviation (WSSAD). Qualitatively, all the wall shear parameters proved to be highly reproducible. Quantitatively, the reproducibility was over 90% for OSI and WSSAD, but less impressive (60%) for other parameters. Our results indicated that WSS and WSSG values were extremely sensitive to subtle variations in local geometry and mesh design, particularly in regions around the bifurcation apex where WSS values were high and least reproducible.

Quantification of the non-planarity of the human carotid bifurcation

The carotid bifurcation has been a region of particular interest due to its predilection for clinically significant atherosclerosis. It has been shown that the vessel geometry is a major determinant of the local haemodynamic properties which are believed to be associated with the location of atherosclerotic lesions. Current knowledge of the geometry of the carotid bifurcation is insufficient and restricted to basic geometric parameters. To provide some means of quantifying the degree of complexity of the 3D shape of the bifurcation, we made an initial attempt by evaluating the non-planarity of an arterial bifurcation based upon the singular value decomposition theorem. In this paper we present our results obtained on the right carotid bifurcations of six normal subjects, each of whom was scanned twice using the 2D time-of-flight MR sequence. The acquired 2D cross sectional images were processed by using our in-house software which comprises 2D segmentation, 3D reconstruction and smoothing. The centroids of each transverse slices were determined and used as input data for the non-planarity analysis. Our results using the singular value decomposition method have demonstrated discernible differences in non-planarity among individuals. Comparisons with the planarity definition proposed by other investigators suggest that the singular value decomposition method offers more information about the linearity and planarity of the bifurcation. However, it is also realised that a single measure of non-planarity can never fully characterise a bifurcation owing to the great variety of geometries.