Associations and Potential Multiple Mechanisms between Subjective Hearing Loss and Cognitive Impairment.

BACKGROUND: Subjective hearing loss (SHL) refers to an individual's self-assessment of their hearing loss. The association and underlying mechanisms between SHL and cognitive impairment still necessitate elucidation. OBJECTIVES: To validate potential mechanisms between SHL and cognitive impairment. DESIGN: Cross-section. SETTING: Shanghai, China. PARTICIPANTS: A total of 2369 individuals from communities and the cognitive disorder clinic. MEASUREMENTS: All participants were subjected to a comprehensive neuropsychological assessment, encompassing the Hearing Handicap Inventory for the Elderly-Screening Version (HHIE-S). The participants' brain ß-amyloid (Aß) deposition status, plasma biomarkers associated with Alzheimer's disease (AD), and cardiovascular risk factors were also collected. RESULTS: In individuals with a heightened SHL, elevated HHIE-S score was linked to diminished cognitive and daily functioning as well as heightened levels of depressed mood. This correlation was observed in auditory memory performance but not in visual memory. The influence of SHL on cognitive function was mediated by depressed mood. SHL was associated with diabetes and smoking, whereas cognitive function was associated with hyperlipidemia and alcohol consumption. In individuals with positive brain Aß deposition, SHL demonstrated associations with cognitive function independent of plasma Aß42/40 ratio, P-tau181, neurofilament light chain, and APOE allele status. CONCLUSION: SHL has an independent effect on cognitive impairment. The findings do no provide evidence for the common cause mechanism. Instead, the findings support the presence of a cognitive resource mechanism and an impoverished environment mechanism, along with the potential for a pathological interaction mechanism.

Chinese Preclinical Alzheimer's Disease Study (C-PAS): Design and Challenge from PET Acceptance.

BACKGROUND: Large-scale preclinical Alzheimer's disease study based on ß-amyloid positron emission tomography (PET) has not been conducted in China. OBJECTIVES: Establish a cohort on Alzheimer's disease spectrum, especially the preclinical stages, and determine the factors influencing the acceptance of ß-amyloid PET scan screening in China. DESIGN: Longitudinal. SETTING: Shanghai, China. PARTICIPANTS: A total of 4386 participants were screened and 2451 participants who met enrollment criteria were eventually included in this report. MEASUREMENTS: The multidimensional data was collected, including comprehensive assessments, PET and magnetic resonance imaging scans, genetics, and plasma biomarkers. RESULTS: There were 571 participants in the normal cognition group, 625 participants in the subjective cognitive decline group, 155 participants in the objectively defined subtle cognitive decline group, 501 participants in the mild cognitive impairment group, 471 participants in Alzheimer's disease group, and 128 participants with cognitive impairment from other known causes. Significant differences in demographics, florbetapir PET, APOE, and neuropsychological tests were found among the groups. Eight hundred and seventeen participants (33.3%) completed the florbetapir PET scanning. Non-demented individuals with higher age, lower education years, male, with a family history of dementia, and higher self-report depression prefer to undergo PET scans. Acceptance of PET scans did not correlate with objectively assessed cognitive impairment. CONCLUSIONS: The Chinese Preclinical Alzheimer's Disease Study was designed to establish a large-scale cohort with comprehensive data collection. Our findings may help to understand the factors affecting the acceptance of ß-amyloid PET in urban areas of China and help us address the low acceptance challenge.

[Discussion on relevant issues of Technical Specifications for Occupational Health Surveillance (GBZ 188-2014)].

Technical Specifications for Occupational Health Surveillance (GBZ 188-2014) is an important basis for judging suspected occupational diseases and occupational contraindications. There are crossing over or overlap between occupational contraindications and diagnostic criteria of poisoning damage. Occupational contraindications have different meanings with the degree and range of common diseases or symptoms and the frequency of physical examination during employment conflicts with the current standard. Based on the practice of occupational health examination in a large population, the present study analyzed relevant articles and put forward some suggestions for revision, in combination with clinical medicine, occupational health standards, and diagnostic standards of occupational diseases. The modification could provide a reference for the revision of Technical Specifications for Occupational Health Surveillance and the practice of occupational health examination.

[Clinical features of 123 patients with hyperinsulinemic hypoglycemia auxiliarily diagnosed by 18F-DOPA-PET CT scanning].

Objective: To summarize the clinical features and therapeutic outcomes of patients with hyperinsulinemic hypoglycemia (HH) auxiliarily diagnosed by 18F-DOPA positron emission tomography (PET) CT scanning. Methods: The clinical data of 123 patients who were diagnosed with hyperinsulinemic hypoglycemia by comprehensive clinical diagnostic procedures in the Department of Pediatric Endocrinology and Inherited Metabolic Diseases, Children's Hospital of Fudan University between January 2016 and December 2020 were retrospectively analyzed. Clinical data such as gender, age of onset, province, concurrent serum insulin level measured during hypoglycemia, lesion type of pancreas by 18F-DOPA-PET CT scanning, genetic test results, and treatment were collected successively. The clinical features and therapeutic outcomes were compared between patients with focal and diffuse pancreatic lesions. T test, Rank sum test, and χ² test were used for comparison between groups. Results: A total of 123 patients with hyperinsulinemic hypoglycemia (72 males and 51 females), whose average age of onset was 3 days (ranging from 1 day to 4 860 days), were recruited from 24 provinces. The concurrent serum insulin level was 7.1 (0.4-303.0) mU/L during hypoglycemia. 18F-DOPA-PET CT scanning identified focal lesions in 25.2% (31/123) and diffuse lesions in 74.8% (92/123) of the patients; 64.2% (79/123) of the HH cases were found to have pathogenic gene variants, in which 88.6% (70/79) were found to have KATP channel related genes (61 in ABCC8 and 9 in KCNJ11 mutations). Thirty-seven patients (17 focal and 20 diffuse) received surgical treatment with a success rate of 67.6% (25/37). The effective rate of diazoxide for children with diffuse type was significantly higher than that of children with focal group (28.3% (26/92) vs. 9.7% (3/31), χ²=10.31, P=0.001). Conclusions: 18F-DOPA-PET CT scan can improve the success rate of surgery. Comprehensive diagnosis of the etiology of hyperinsulinemic hypoglycemia by genetic analysis and 18F-DOPA-PET CT scanning can result in better treatment and prognosis.

Overexpression of long non-coding RNA MINCR contributes to progressive clinicopathological features and poor prognosis of human hepatocellular carcinoma.

OBJECTIVE: MYC-induced long non-coding RNA (MINCR) has been shown to be a long noncoding RNA that facilitates the progression of a number of malignancies, including hepatocellular carcinoma (HCC). However, few studies have explored the expression and role of MINCR in HCC. In this study, we aimed to investigate the clinical significance of MINCR in HCC. PATIENTS AND METHODS: MINCR expression levels in 161 pairs of HCC tissues and pair-matched adjacent normal tissues were examined by qRT-PCR. The correlation between clinicopathological features and MINCR expression was analyzed by x2 test. Differences in patient survival were determined using the Kaplan-Meier method and a log-rank test. The significance of survival variables was analyzed using the Cox multivariate proportional hazards model. RESULTS: Our results showed that MINCR was significantly upregulated in HCC tissues, compared with paired adjacent nontumor tissue samples. MINCR upregulation was correlated with TNM stage (p = 0.005) and histological grade (p = 0.001). The results of Kaplan-Meier method and log-rank test indicated that the 5-years overall survival of the high MINCR group was significantly lower than that of low MINCR group (p = 0.0035). Univariate and multivariate analysis results indicated that MINCR was an independent prognostic factor in HCC (p < 0.05). CONCLUSIONS: We firstly provided the possibility that evaluating MINCR in HCC tissues may have prognostic and predictive value in the clinical management of HCC patients.

[Feasibility of domestic (18)F-DOPA PET/CT scanning in the differential diagnosis of pancreatic lesions in children with hyperinsulinemic hypoglycemia].

Objective: To study the feasibility of (18)F-fluoro-L-dihydroxyphenylalanine positron emission tomography/Computed tomography ((18)F-DOPA PET/CT) scanning in the localization and differential diagnosing of focal versus diffuse form of pancreas lesions in patients with hyperinsulinemic hypoglycemia (HH). Method: Twenty-four patients were diagnosed with HH between January, 2016 and February, 2017 in the Department of Pediatric Endocrinology and Inherited Metabolic Diseases, Children's Hospital of Fudan University using an integrated clinical and biochemical diagnostic protocol, domestic (18)F-DOPA PET/CT imaging technique were applied after MRI and ultrasound failed to detect pancreas lesions. Pancreas (18)F-DOPA standardized uptake values (SUV) were measured, and pancreas' lesions were dually analyzed via visual method and pancreas percentage SUV method. Among these patients, 9 patients received surgical pancreatic lesion resections, the correlations among surgical outcomes, histopathological findings and (18)F-DOPA PET/CT scan results were analyzed. Result: Seven patients were detected with focal form of pancreas lesions, the mean peak of SUV was 4.7±1.7(2.6-7.1), and 17 patients were found to have diffuse form lesions after (18)F-DOPA-PET/CT scanning. Among the 24 cases, 9 patients (7 showed focal and 2 showed diffuse (18)F-DOPA PET/CT pancreatic uptake)were euglycemic without any medical support after surgery; the resected pancreatic tissue histopathological results were consistent with that of PET/CT imaging. Only one patient, who responded to medical treatment before surgery, had temporary hyperglycemia after operation. Conclusion: Domestic (18)F-DOPA PET/CT could successfully locate and differentiate the pancreatic lesions and thus improve the success of surgery.

[Role of glucose-6-phosphate dehydrogenase in hepatitis B virus replication and its possible mechanism of action].

OBJECTIVE: To investigate the role of glucose-6-phosphate dehydrogenase (G6PD) in hepatitis B virus (HBV) replication and its possible mechanism of action. METHODS: Tissue microarray, quantitative real-time PCR, and Western blot were performed to analyze the differences in G6PD expression levels in the HBV-positive and HBV-negative liver tissues, HepG2.2.15 cells, and HepG2 cells. The siRNA transfection technique was used to knock down G6PD gene in HepG2.2.15 cells for 48 hours. Chemiluminescence was used for HBsAg and HBeAg quantification in supernatant, and quantitative real-time PCR was used to measure HBV DNA, type I interferon (IFN), and downstream IFN-stimulated genes. The t-test was used for comparison between groups. RESULTS: G6PD expression was significantly upregulated in the HBV-positive liver tissues and cells compared with HBV-negative liver tissues and cells, and the stain intensity and immunohistochemical scores were 89.69±54.92 and 31.90±18.62, respectively (P < 0.05). After G6PD expression in HepG2.2.15 cells was interfered by siRNA, the quantitative levels of HBV DNA, HBsAg, and HBeAg in supernatant were reduced significantly, and the mRNA expression levels of IFNα1, IFNß1, and five downstream IFN-stimulated genes (OAS1, ISG15, OAS3, EIF2α, and PKR) increased significantly (all P < 0.05). CONCLUSION: G6PD plays a vital role in HBV replication, and its mechanism of action in regulating HBV replication may be related to type I IFN signaling pathway.

System wide cofactor turnovers can propagate metabolic stability between pathways.

Metabolic homeostasis, or low-level metabolic steady state, has long been taken for granted in metabolic engineering, and research priority has always been given to understand metabolic flux control and regulation of the reaction network. In the past, this has not caused concerns because the metabolic networks studied were invariably associated with living cells. Nowadays, there are needs to reconstruct metabolic networks, and so metabolic homeostasis cannot be taken for granted. For metabolic steady state, enzyme feedback control has been known to explain why metabolites in metabolic pathways can avoid accumulation. However, we reasoned that there are further contributing mechanisms. As a new methodology developed, we separated cofactor intermediates (CIs) from non-cofactor intermediates, and identified an appropriate type of open systems for operating putative reaction topologies. Furthermore, we elaborated the criteria to tell if a multi-enzyme over-all reaction path is of in vivo nature or not at the metabolic level. As new findings, we discovered that there are interactions between the enzyme feedback inhibition and the CI turnover, and such interactions may well lead to metabolic homeostasis, an emergent property of the system. To conclude, this work offers a new perspective for understanding the role of CIs and the presence of metabolic homeostasis in the living cell. In perspective, this work might provide clues for constructing non-natural metabolic networks using multi-enzyme reactions or by degenerating metabolic reaction networks from the living cell.

Evaluation of cesium-137 conversion models and parameter sensitivity for erosion estimation.

The Cs technique has been widely used to provide soil redistribution estimates since the 1970s. However, most Cs-conversion models remain theoretical and largely unvalidated. Our objectives were to validate the four widely used conversion models, examine model parameter sensitivity, and evaluate the potential of using kriging to improve soil redistribution estimation. Soil loss was measured from a 1.6-ha plot since 1978. Winter wheat ( L.) was grown primarily under conventional tillage. Soil samples in a 10-m grid were taken from the plot to estimate the Cs inventory. Soil redistribution rates were estimated using four models and were further interpolated using ordinary kriging. The parameter sensitivity analyses at the 95% confidence limits showed that reference inventory had the most impact on estimated water erosion, followed by particle size correction for erosion and tillage depth, with minimal impacts from mass depth, bulk density, and particle size correction for deposition. Compared with the measured water erosion, the relative errors of the mean net water erosion estimates across the entire plot without and with kriging were 28 and -17% for the proportional model (PM), 141 and 106% for the simplified mass balance model, 133 and 100% for the improved mass balance model (MBM2), and 109% for the extended MBM2 with tillage erosion (MBM3). Results indicated that the PM performed better than the mass balance models under the study conditions and that kriging improved mean soil redistribution estimates. However, the full potential of the MBM2 and MBM3 needs to be further evaluated under conditions where loss of newly deposited Cs exists.

Stability in brain glucose metabolism following brown adipose tissue inactivation in chinese adults.

BACKGROUND AND PURPOSE: The thermogenesis of BAT is believed to be controlled through some pathways initiated in the brain, though the changes in brain activity among different states of BAT-positive subjects are still unclear. We hypothesized that some significant differences of regional cerebral metabolism between various groups were related to the BAT activities regardless of temperature changes. MATERIALS AND METHODS: Relative regional cerebral glucose metabolism was compared between 15 healthy subjects with activated BAT and 30 healthy controls without activated BAT by using a brain FDG-PET scan. A follow-up PET scan was performed to assess metabolic changes of the brain when BAT activity was eliminated by heat exposure. RESULTS: Compared with controls, BAT-positive subjects exhibited lower activity in the inferior parietal lobule, limbic system, and frontal lobe and higher activity in the precuneus before heat exposure. Compared with the BAT elimination status, subjects with activated BAT showed a decreased metabolism in the parietal lobe, frontal lobe, culmen, cingulate gyrus, and sublobar region. Compared with controls, BAT-positive subjects after BAT inactivation had significant hypometabolic areas in the temporal lobe and limbic lobe and hypermetabolic areas in the parietal lobe. CONCLUSIONS: Our findings illustrate that changes of regional cerebral metabolism are related to BAT activities regardless of temperature changes. This before-after controlled study supports the finding that the brain responses appear to be active in modulating the metabolic function of BAT activity.

The three-dimensional model for helical columns on type-J synchronous counter-current chromatography.

Unlike the existing 2-D pseudo-ring model for helical columns undergoing synchronous type-J planetary motion of counter-current chromatograph (CCC), the 3-D "helix" model developed in this work shows that there is a second normal force (i.e. the binormal force) applied virtually in the axial direction of the helical column. This force alternates in the two opposite directions and intensifies phase mixing with increasing the helix angle. On the contrary, the 2-D spiral column operated on the same CCC device lacks this third-dimensional mixing force. The (principal) normal force quantified by this "helix" model has been the same as that by the pseudo-ring model. With ß>0.25, this normal centrifugal force has been one-directional and fluctuates cyclically. Different to the spiral column, this "helix" model shows that the centrifugal force (i.e. the hydrostatic force) does not contribute to stationary phase retention in the helical column. Between the popular helical columns and the emerging spiral columns for type-J synchronous CCC, this work has thus illustrated that the former is associated with better phase mixing yet poor retention for the stationary phase whereas the latter has potential for better retention for the stationary phase yet poor phase mixing. The methodology developed in this work may be regarded as a new platform for designing optimised CCC columns for analytical and engineering applications.

Reversible changes in brain glucose metabolism following thyroid function normalization in hyperthyroidism.

BACKGROUND AND PURPOSE: Patients with hyperthyroidism frequently present with regional cerebral metabolic changes, but the consequences of endocrine-induced brain changes after thyroid function normalization are unclear. We hypothesized that the changes of regional cerebral glucose metabolism are related to thyroid hormone levels in patients with hyperthyroid, and some of these changes can be reversed with antithyroid therapy. MATERIALS AND METHODS: Relative regional cerebral glucose metabolism was compared between 10 new-onset untreated patients with hyperthyroidism and 20 healthy control participants by using brain FDG-PET scans. Levels of emotional distress were evaluated by using the SAS and SDS. Patients were treated with methimazole. A follow-up PET scan was performed to assess metabolic changes of the brain when thyroid functions normalized. RESULTS: Compared with controls, patients exhibited lower activity in the limbic system, frontal lobes, and temporal lobes before antithyroid treatment. There were positive correlations between scores of depression and regional metabolism in the cingulate and paracentral lobule. The severity of depression and anxiety covaried negatively with pretreatment activity in the inferior temporal and inferior parietal gyri respectively. Compared with the hyperthyroid status, patients with normalized thyroid functions showed an increased metabolism in the left parahippocampal, fusiform, and right superior frontal gyri. The decrease in both FT3 and FT4 was associated with increased activity in the left parahippocampal and right superior frontal gyri. CONCLUSIONS: The changes of regional cerebral glucose metabolism are related to thyroid hormone levels in patients with hyperthyroidism, and some cerebral hypometabolism can be improved after antithyroid therapy.

Protein separation using toroidal columns by type-J synchronous counter-current chromatography towards preparative separation.

Separation of large bioactive molecules such as proteins, DNAs and RNAs using aqueous two-phase systems (ATPSs) and liquid-liquid partition-based counter-current chromatography (CCC) can avoid risks of sample loss and denaturation, and greatly reduce processing time. We have constructed toroidal columns (length 26-140 m, column volume 51-280 ml, bore size 1.6 mm) suitable for mounting onto a commercially available preparative CCC apparatus. With the use of an ATPS containing 12.5% (w/w) PEG1000 and 12.5% (w/w) K(2)HPO(4) and at a rotational speed of 800 rpm for the rotor of the CCC device, the lower phase (i.e. the phosphate-enriched phase) has been used as the mobile phase and a pair of proteins, myoglobin and lysozyme, as model proteins for demonstrating the separation capability of the CCC system. For a toroidal column with a length of 53.5 m and a column volume of 107.5 ml, and operated for the Coriolis force parallel flow mode at 0.62 ml/min, protein sample loading (containing 2.2 mg/ml myoglobin and lysozyme, respectively) at 1.7% and 7.4% to the column volume led to peak resolution (with theoretical plate number TP and stationary phase retention S(f) shown in the parenthesis) of R(s)=1.5 (N=211 and N=113 TP for myoglobin and lysozyme, respectively, and S(f)=45.0%), and R(s)=1.4 (218 and 152 TP, and S(f)=34.0%). However, further increase of the loading to 13% failed to separate the two proteins. Although proteins eluted at positions predictable from the distribution coefficients, they showed broader peaks when compared with small dipeptides under identical CCC operating conditions. This confirms that the molecular weight of the partitioned species is an important factor causing peak broadening on CCC chromatograms. These results paved the way for further scaling-up toroidal CCC columns for processing larger quantities of samples containing large biomolecules.

Clinical features of hepatic myelopathy in patients with chronic liver disease.

AIM: To determine the clinical features of hepatic myelopathy (HM), a rare condition associated with chronic liver disease (CLD), in patients in the city of Harbin, China. METHODS: The medical files of 13 patients with HM were selected from 500 randomly chosen files of CLD patients registered in four Harbin hospitals. General information on all cases was summarised and clinical features were compared between HM positive patients (HM group) and HM negative CLD patients (control group). Detailed analysis of the clinical characteristics of HM positive patients was undertaken. RESULTS: The patients in the HM group ranged in age from 41-50 years, which did not differ significantly from the control group. However, the sex ratio in the HM group (12 males/1 female) was significantly higher (p<0.05) than in the control group (342 males/145 females).The most frequent underlying aetiology was post type B hepatitis (12 cases). All cases in the HM group had a history of relapsing hepatic encephalopathy (HE) before or after HM onset, and showed electroencephalographic (EEG) abnormalities; however, the results of spinal cord magnetic resonance imaging were negative, and cerebrospinal fluid analysis findings were normal. Except for clinical manifestations of bilateral lower limb spastic paralysis, the two groups did not differ significantly in regard to other symptoms or signs. Hypoproteinaemia (positive predictive value (PPV) 5.69%, negative predictive value (NPV) 99.65%), blood ammonia elevation (PPV 5.29%, NPV, 99.32%) and abnormal EEG (PPV 5.00%, NPV 100.00%) were sensitive and specific for HM diagnosis. CONCLUSION: In Harbin, HM is found mainly among middle aged men with CLD caused by viral hepatitis and accompanied by relapsing onset of HE. Bilateral lower limb spastic paralysis with hypoproteinaemia, blood ammonia elevation and/or abnormal EEG are significant diagnostic indicators of HM.

Measurement of stain on extracted teeth using spectrophotometry and digital image analysis.

AIM: The aim of this study was to assess the reliability and validate a customized image analysis system, designed for use within clinical trials of general dental hygiene and whitening products, for the measurement of stain levels on extracted teeth and to compare it with reflectance spectrophotometry. METHOD: Twenty non-carious extracted teeth were soaked in an artificial saliva, brushed for 1 min using an electric toothbrush and a standard toothpaste, bleached using a 5.3% hydrogen peroxide solution and cycled for 6 h daily through a tea solution. CIE L* values were obtained after each treatment step using the customized image analysis system and a reflectance spectrophotometer. A statistical analysis was carried out in SPSS. RESULTS: Fleiss' coefficient of reliability for intra-operator repeatability of the image analysis system and spectrophotometry was 0.996 and 0.946 respectively. CIE L* values were consistently higher using the image analysis compared with spectrophotometry, and t-tests for each treatment step showed significant differences (P < 0.05) for the two methods. Limits of agreement between the methods were -27.95 to +2.07, with a 95% confidence of the difference calculated as -14.26 to -11.84. The combined results for all treatment steps showed a significant difference between the methods for the CIE L* values (P < 0.05). CONCLUSION: The image analysis system has proven to be a reliable method for assessment of changes in stain level on extracted teeth. The method has been validated against reflectance spectrophotometry. This method may be used for pilot in vitro studies/trials of oral hygiene and whitening products, before expensive in vivo tests are carried out.

Model for spiral columns and stationary phase retention in synchronous coil planet centrifuges.

Stationary phase retention in a synchronous coil planet centrifuge or high-speed counter-current chromatography (CCC) relies on the interplay of hydrostatic (tangential and normal centrifugal) and hydrodynamic (Archimedean screw and mobile phase drag) forces. By offering a set of quantitative or semi-quantitative theoretical frameworks, this work has resolved fundamental questions such as "in the absence of mobile phase flow, how is the distribution of the two phases in a CCC column determined?" and "for Type-J CCC, do the helical and the spiral columns lead to similar performance?"

A digital image analysis system for the assessment of tooth whiteness compared to visual shade matching.

OBJECTIVE: To assess tooth whiteness clinically using an image analysis system and a whiteness algorithm to compare with visual shade matching. METHODOLOGY: Images of the maxillary anterior teeth of 20 subjects were obtained using an image analysis system adapted for tooth whiteness measurement. Red, green, and blue values from each image, and Commision Internationale de l'Eclairage whiteness index (CIE WI) values were calculated. A visual shade match was also carried out using a Vitapan 3D Master 26-tab shade guide. RESULTS: The range of CIE WI values for image analysis and visual shade matching was 32.86-85.91 and 32.68-79.84, respectively. Limits of agreement between methods were +17.71 and -14.60 CIE WI units. The 95% confidence interval of the difference was calculated as -0.176 to +3.083. A two-tailed Student t-test with a 95% confidence level showed significant differences (p = 0.028) between the paired CIE WI values of each tooth for the two measurement techniques. As the accuracy and reliability of the image analysis system was found to be high in previous in vitro studies, the differences between the two methods were probably related to the inherent subjectivity of visual shade matching. CONCLUSION: The adapted digital image analysis system could be used as an alternative to, or in conjunction with visual shade matching.

Spiral coils for counter-current chromatography using aqueous polymer two-phase systems.

Retention properties of polyethylene glycol-phosphate aqueous two-phase systems in a spiral coil (5 mm I.D.) on Type-J synchronous counter-current chromatographic devices have been compared for the elution mode where the lower phase is the mobile phase and flows from the inside head terminal. This was achieved with the aid of digital imaging under stroboscopic illumination, an image analysis and measurement of the displaced volume of the stationary phase. For the spiral coil, high and stable stationary phase retention at mobile phase flow rates up to 64 ml/min has been obtained. Wave-like disturbance of the interface near the proximal point was observed and analyses have been made for possible use in protein separation.

The measurement of tooth whiteness by image analysis and spectrophotometry: a comparison.

Digital image capturing and analysis techniques have been used to measure the colour of teeth and to compare with spectrophotometric results and visual observations. A non-linear image analysis approach was developed and, for the colour range of human teeth, allows device-dependant digital camera colour data to be quantitatively transformed to Commission Internationale de l'Eclairage (CIE) colorimetric values. With reference to a CIE standard illuminant, two different lighting arrays have been used. For flat and non-translucent white and yellow surfaces, spectrophotometric results showed that this transformation achieves required accuracy. It was found, in all of the present studies, which included measurements on the VITA Lumin Vacuum shade guide and extracted teeth, that spectrophotometry invariably underestimated values of the CIE whiteness index. However, the results from these two types of measurement correlated well. There was also a reasonably good correlation between earlier data obtained by visual assessment and the present data by the two instrumental methods. For extracted teeth, both instrumental methods used in this work did not confirm a whitening effect for 2-min brushing with toothpaste, but did show significant whitening results for bleaching with 15% hydrogen peroxide.