Weak electron-phonon coupling contributing to high thermoelectric performance in n-type PbSe

PbSe is a surprisingly good thermoelectric material due, in part, to its low thermal conductivity that had been overestimated in earlier measurements. The thermoelectric figure of merit, zT, can exceed 1 at high temperatures in both p-type and n-type PbSe, similar to that found in PbTe. While the p-type lead chalcogenides (PbSe and PbTe) benefit from the high valley degeneracy (12 or more at high temperature) of the valence band, the n-type versions are limited to a valley degeneracy of 4 in the conduction band. Yet the n-type lead chalcogenides achieve a zT nearly as high as the p-type lead chalcogenides. This effect can be attributed to the weaker electron-phonon coupling (lower deformation potential coefficient) in the conduction band as compared with that in the valence band, which leads to higher mobility of electrons compared to that of holes. This study of PbSe illustrates the importance of the deformation potential coefficient of the charge-carrying band as one of several key parameters to consider for band structure engineering and the search for high performance thermoelectric materials.     

High performance liquid chromatographic analysis of insulin degradation by rat skeletal muscle insulin protease

The degradation of [125I]iodoinsulin (A14) by insulin protease (EC 3.4.22.11) was studied using HPLC. A reverse phase HPLC method is presented which allows the separation and quantitation of insulin degradation products. After incubation of [125I]iodoinsulin (A14) with insulin protease, there was an initial rapid loss of radioactivity from the [125I] iodoinsulin (A14) peak, which was quantitatively accounted for by the appearance of radioactivity in 11 different peaks, but was not accompanied by a proportional increase in the solubility of the sample in trichloroacetic acid. Two of the peaks showed appreciable accumulation before the others, and all but the first-eluted peak plateaued by 20 min. After 20 min of incubation, the amount of radioactivity present as the first-eluted peak, solubility in trichloroacetic acid, and insulin loss continued to increase at a steady, but slowed, rate. The order of appearance suggests that insulin protease acts on insulin in an ordered sequence of steps to generate a number of intermediates that are precipitable by trichloroacetic acid, but are subsequently degraded to material that is soluble in trichloroacetic acid. Sulfitolysis of 5 major peaks and subsequent HPLC analysis of the fragments showed none of the peaks to possess intact A chains. Peptide sequencing of 2 of the peaks indicates that the A-chain is cleaved in at least 2 positions, one beyond the 14th position, and one between the 13th and 14th amino acids (leucine and tyrosine).     

An evaluation of indium DTPA chelate in the measurement of gastric emptying by scintiscanning

The sequential scintiscanning technique was used to determine gastric emptying rates in adult human subjects after ingestion of a meal of cornflakes and milk to which a gamma-emitting radioactive isotope had been added.

Comparison of emptying rates using ^113mIn DTPA chelate and ⁵¹Cr sodium chromate showed that significantly slower rates were recorded with chromate, and studies in vitro demonstrated adsorption of chromate to the solid component of the meal. The results imply that the liquid phase of the gastric contents after a meal is discharged through the pylorus more rapidly than the solid phase. Scintiscanning with indium chelate provides a measurement of the emptying of the liquid phase of the gastric contents.

     

Surface layering and melting in an ionic liquid studied by resonant soft X-ray reflectivity

The molecular-scale structure of the ionic liquid [C₁₈mim]⁺[FAP]⁻ near its free surface was studied by complementary methods. X-ray absorption spectroscopy and resonant soft X-ray reflectivity revealed a depth-decaying near-surface layering. Element-specific interfacial profiles were extracted with submolecular resolution from energy-dependent soft X-ray reflectivity data. Temperature-dependent hard X-ray reflectivity, small- and wide-angle X-ray scattering, and infrared spectroscopy uncovered an intriguing melting mechanism for the layered region, where alkyl chain melting drove a negative thermal expansion of the surface layer spacing.     

High diagnostic performance of ELISA detection of antibodies to citrullinated antigens in rheumatoid arthritis

OBJECTIVE: We investigated the rheumatoid arthritis (RA) diagnostic performances of anti-cyclic citrullinated peptide antibody (anti-CCP) and antifilaggrin antibody (AFA) in comparison with RF and matrix metalloproteinase-3 (MMP-3). METHODS: We used a second generation enzyme-linked immunosorbent assay (ELISA) kit for the detection of anti-CCP. We constructed recombinant human filaggrin, which was citrullinated in vitro by human peptidylarginine deiminase, and subsequently used it as the coating antigen for AFA-ELISA. A total of 549 RA patients and 208 other rheumatic disease patients were included in the study. RESULTS: The specificities of anti-CCP (88.9%) and AFA (94.7%) were superior to those of RF (81.7%) and MMP-3 (49.5%). The sensitivity of anti-CCP (87.6%) was superior to all others. However, the sensitivity of AFA (68.7%) was inferior to those of RF (69.8%) and MMP-3 (75.7%). Furthermore, receiver operating characteristic curves of anti-CCP and AFA passed closer to the upper left corner than those of RF and MMP-3, and the areas under the curves (AUC) of AFA and anti-CCP were significantly larger. In addition, the AUC of anti-CCP was significantly larger than that of AFA. CONCLUSION: ELISA detection of antibodies to citrullinated antigens, especially a second generation anti-CCP, showed higher discriminative ability than other assays, including RF, and would be useful to aid the diagnosis of RA in clinical practice.     

Cardiac performance in collagen diseases estimated by non-invasive methods

The myocardial performance was studied in 3 collagen diseases, i.e. rheumatoid arthritis (RA), systemic lupus erythematosus (SLE) and progressive systemic sclerosis (PSS). Sixteen patients with SLE, 12 with RA and 11 with PSS were examined, measuring the systolic time intervals from the first derivative of the carotid pulse in all cases. The ejection fraction (EF), was evaluated in 33 patients using radionuclide left ventricular angiography. The systolic time intervals were compared to those of 103 normal persons and the EF to that of 22 normal controls. In the SLE group the pre-ejection period was significantly shorter, while the ejection period was longer than normally expected. In the same group, the EF was significantly higher that the EF of the control group. These differences could not be related to age, blood pressure, disease duration, coronary risk factors, heart rate or blood values. Most findings in the RA group tended to be opposite to those of SLE. It is concluded that in SLE before any direct involvement of the heart the systolic time intervals and the EF present features similar to those of increased cardiac performance.     

高糖高脂对培养成年小鼠心肌细胞的氧化应激损伤

目的:建立培养成年小鼠心肌细胞模型,给予高糖高脂刺激观察是否可以引起心肌细胞损伤和凋亡,并分析其机制.方法:分离培养成年小鼠心肌细胞,以最小必需培养基(minimum essential medium,MEM)加20 mmol/L甘露醇作为正常对照培养基(正常对照组,n=10);以MEM+高糖(20 mmol/L葡萄糖)高脂(50 μmol/L软脂酸)培养模拟糖尿病(高糖高脂组,n=10),心肌细胞分别在两种培养基中培养24 h后测定指标.结果:高糖高脂组乳酸脱氢酶(LDH)、细胞凋亡蛋白酶caspase-3活性显著升高,过氧化亚硝基损伤标志物硝基酪氨酸生成增多,同时心肌诱生型一氧化氮合酶(iNOS)蛋白表达水平和一氧化氮(NO)生成增多,烟酰胺腺嘌呤二核苷酸磷酸(NADPH)氧化酶蛋白表达水平和超氧阴离子生成增多,与正常对照组比较,差异均有统计学意义(P均<0.01).结论:在培养的成年小鼠心肌细胞,高糖高脂可引起心肌细胞损伤和凋亡,这主要是由于高糖高脂引起的iNOS大量表达所生成的NO和NADPH氧化酶表达增高生成的超氧阴离子反应产生的大量过氧化亚硝基所诱发.     

Glucose monitoring by microdialysis: performance in a multicentre study

Aims The aim of this study was to assess the performance of the Continuous Research Tool (CRT) in a multicentre clinical‐experimental study. Methods Three patient groups totalling 28 subjects with diabetes [group A 10 Type 1 (Ulm), group B 10 Type 1 (Neuss), group C eight Type 2 (Aarhus)] participated in this trial. Two CRT microdialysis probes were inserted in parallel in the abdominal subcutaneous tissue for 120 h in each subject. In subjects in group A, glucose excursions were induced on one study day and those in group B underwent a glucose clamp (eu‐, hypo‐ or hyperglycaemic) on one study day. CRT data were calibrated once with a retrospective calibration model based on a run‐in time of 24 h and three blood glucose measurements per day. Results All analysable experiments, covering a broad range of blood glucose values, yielded highly accurate data for the complete experimental time with a mean relative absolute difference of 12.8 ± 6.0% and a predictive residual error sum of squares of 15.6 ± 6.3 (mean ± SD). Of all measurement results, 98.2% were in zones A and B of the error grid analysis. The average absolute differences were 1.14 mmol/l for Type 1 and 0.88 mmol/l for Type 2 diabetic patients. Relative absolute differences were 16.0% for Type 1 and 12.6% for Type 2 diabetic patients. Conclusions These results demonstrate that this microdialysis system allows reliable continuous glucose monitoring in patients with diabetes of either type.     

Echocardiographic evaluation of changes in cardiac performance induced by hemodialysis

For the purpose of assessing the cardiovascular effects of hemodialysis (HD), M-mode echocardiography was performed 24 hours before and 2 hours after this procedure in 15 patients with chronic renal failure. The results, which include computer analysis of digitized interventricular septum (IVS) and left ventricular posterior wall (LVPW), show the following statistically significant changes after HD: reduction of end-diastolic and end-systolic internal diameters of the left ventricle (LVID), increase of mean velocity of circumferential fiber shortening, of peak rate of systolic and diastolic LVID variation, of systolic and diastolic LVPW movement, and of IVS movement in systole. These results demonstrate that after HD the left ventricle not only decreases in size but also its performance improves in both contraction and relaxation. These changes did not correlate with the reduction in body weight and arterial pressure following HD; hence HD seems to act on left ventricular function by reducing mainly afterload and, possibly, by modifying some humoral parameters. In conclusion, M-mode echocardiography, especially when utilized in conjunction with the computerized analysis of the recordings, is useful and reliable in monitoring hemodynamic changes occurring during the dialytic session.     

Prejudice in performance evaluation of so-called elderly co-workers by supervisors

This empirical interview study analyses the opinions of supervisors in an industrial company about their so-called elderly co-workers. These opinions are insofar relevant to the co-workers, as it is the direct supervisor who decides on the consequences of the real or supposed reduction in performance. The analysis shows that the beginning of a reduction in performance is set at the age of about 45-50 years. These and other opinions are dependent on various personal and situational factors as could be shown by means of a tree analysis.     

Alterations in ventricular mass and performance induced by exercise training in man evaluated by echocardiography

Few data are available regarding the effects of exercise training upon cardiac structure and performance in man. We evaluated the echograms of 24 normals before (PRE) and after (POST) 11 weeks of endurance exercise training. Conditioning consisted of a walk-jog-run protocol at 70% maximal heart rate for one hour four days per week. Training reduced heart rate and increased maximal duration and estimated oxygen consumption of treadmill exercise. Compared to PRE, the echogram in the POST training period revealed an increased left ventricular (LV) end-diastolic dimension (EdD), a decreased end-systolic dimension (EsD) and thus an increased stroke volume (EdD3-EsD3) and shortening fraction (EdD-EsD)/EdD). Cardiac output (CO) and peripheral vascular resistance (BP/CO X 80) were identical PRE and POST conditioning. Importantly, an increase in mean fiber shortening velocity was observed POST training as were increases in LV wall thickness, ECG voltage of S in V1 + R in V5, and LV mass. Thus endurance training was accompanied by increases in both LV dimension and mass as well as LV shortening fraction and contraction velocity as observed by echocardiogram.     

Melatonin in edible plants identified by radioimmunoassay and by high performance liquid chromatography-mass spectrometry

Abstract: Melatonin, the chief hormone of the pineal gland in vertebrates, is widely distributed in the animal kingdom. Among many functions, melatonin synchronizes circadian and circannual rhythms, stimulates immune function, may increase life span, inhibits growth of cancer cells in vitro and cancer progression and promotion in vivo, and was recently shown to be a potent hydroxyl radical scavenger and antioxidant. Hydroxyl radicals are highly toxic by-products of oxygen metabolism that damage cellular DNA and other macromolecules. Herein we report that melatonin, in varying concentrations, is also found in a variety of plants. Melatonin concentrations, measured in nine different plants by radioimmunoassay, ranged from 0 to 862 pg melatonin/mg protein. The presence of melatonin was verified by gas chromatography/mass spectrometry. Our findings suggest that the consumption of plant materials that contain high levels of melatonin could alter blood melatonin levels of the indole as well as provide protection of macromolecules against oxidative damage.     

High grade dysplasia in Crohn's colitis characterized by flow cytometry

A patient with Crohn's ileocolitis had high grade dysplasia. Preoperative evaluation of colonoscopic biopsies by flow cytometry demonstrated aneuploidy, a marker of malignancy. In the surgical specimen, however, carcinoma was not demonstrated despite extensive sampling. The detection of abnormal DNA content in this premalignant lesion suggests a useful role for this technique in selecting those patients with inflammatory bowel disease at risk for carcinoma.     

Neurocognitive performance enhanced by highly active antiretroviral therapy in HIV-infected women

OBJECTIVE: To determine whether highly active retroviral therapy (HAART) is associated with better neurocognitive outcome over time among HIV-infected women with severely impaired immune function. METHODS: A semiannual neurocognitive examination on four tasks was administered: Color Trail Making, Controlled Oral Word Association, Grooved Pegboard and Four-Word Learning. This protocol was initiated in the HIV Epidemiological Research study (HERS) study when a woman's CD4 cell count fell to < 100 x 10(6) cells/l. Immune function (CD4), viral load status and depression severity (CESD) were also assessed semi-annually, along with an interview to determine medication intake and illicit drug use. RESULTS: HAART was not available to any participant at the time of enrollment (baseline), while 44% reported taking HAART at their most recent visit (mean duration of HAART 36.3 +/- 12.6 months). HAART-treated women had improved neurocognitive performance compared with those not treated with HAART. Women taking HAART for 18 months or more showed the strongest neurocognitive performance with improved verbal fluency, psychomotor and executive functions. These functions worsened among women not taking HAART. Substance abuse status, severity of depressive symptoms, age and educational level did not influence the HAART treatment effects on neurocognitive performance. Neurocognitive improvements were strongly associated with the magnitude of CD4 cell count increases. CONCLUSIONS: HAART appeared to produce beneficial effect on neurocognitive functioning in HIV-infected women with severely impaired immune systems. Benefits were greatest for women who reported receiving HAART for more than 18 months.     

黄绿青霉素的高效液相色谱法检测

目的摸索高效液相色谱(HPLC)检测粮食中黄绿青霉素(citreoviridin,CIT)的实用方法。方法以CIT标准品人工污染几种粮食,然后用二氯甲烷提取、过滤、自然干燥、流动相定容、上机。使用日本岛津SPD鄄10Avp液相色谱仪,紫外鄄可见检测器,Hypesil SiO2 色谱柱(4.6 mm ×150 mm,5 μm)。流动相是乙酸乙酯∶正已烷(7∶3)。流速和检测波长分设为0.5 ml/min和388 nm。结果最低检出量为10 ng/g。标准曲线小剂量R1 = 0.999,Se1 = 0.015 532;大剂量R2 = 0.999,Se2 = 0.030 24。回收率82.5%～96.1% 。日间与日内变异均< 2%。结论高效液相色谱检测法灵敏、简捷、经济,适用于地方病病区粮食黄绿青霉素污染水平的检测。     

On-line evaluation of systolic performance by densitometry in digital left ventriculography

The angiocardiographic evaluation of left ventricular end-diastolic (LVEDV) and end-systolic (LVESV) volumes and ejection fraction (EF) is routinely performed by the area-length method (ALM) but may lead to erroneous results. Digital imaging in real time allows densitometric procedures of determining left ventricular (LV) performance to be applied alternatively. In this study, we present densitometric algorithms for the analysis of LVEDV, LVESV, and EF from digital image data, establish accuracy and reproducibility, and determine value and limitations in comparison with ALM in single-plane 30°right anterior oblique (RAO) projection. A linear relationship between iodine depth and measured densities is mainly burdened with scatter radiation and beam hardening which reduce primary radiation and suppress iodine depth. However, facilities such as deconvolution and correction algorithms are capable of reducing these sources of error. In the present study, computer-analyzed contrast images of iodine-filled wedges and spheres showed a near-linear relationship between iodine depth between 50-100 mg/cm² and measured densities. Contrast images of heart casts and LV an-gio-grams of 54 patients were obtained with a digital image acquisition and processing system, and evaluated by two in dependent observers. The phantom study resulted in significantly (p≤0.01) better densitometric standard errors of estimate for volumes [3.3 ml densitometry (DENS) vs. 8.9 ml (ALM)] and simulated EF [4.3% (DENS) vs. 7.8% (ALM)] than ALM. The standard error of estimate for the comparison between both methods was 8.4 ml for volumes and 7.5% for EF. Densitometric volumes tended to underestimate volumes calculated by ALM. The angiographic study of patients demonstrated significant correlations between both methods (LVEDV r = 0.78, LVESV r = 0.83, total volumes: r = 0.89;EF r = 0.88). The standard errors of estimate can be ascribed to systematic, method-related errors of both DENS and ALM (LVEDV ± 28.9 ml, LVESV ± 23.4 ml, total volumes (EDV and ES V) ± 27.1 ml; EF ± 8.1 %). The intra- and interobserv-er variability, respectively, exhibited significantly smaller (p ≤0.01 and p ≤0.05, respectively) standard errors of estimate for densitometric EF [4.6% (DENS) vs. 8.5% (ALM) and 7.1% (DENS) vs. 10.3% (ALM), respectively]. Inclined but not significant differences were found for LVEDV and LVESV. In conclusion, the data presented indicate that the calculation of LV volumes and EF in digital left ventriculography may be performed accurately by densitometric calculation in single-plane 30°RAO projection. Minor underestima-tions in densitometric volume determination may be anticipated in the evaluation of LV geometry.