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Dr A. Ghosh J. S. K. Woo C. W. Wan C. Machenry V. Wong H. K. Ma Vivian Chan T. K. Chan 《黑龙江环境通报》1985,5(1):59-65
Haemoglobin A2 (HbA2) levels were determined on 25 β-thalassaemia carriers by the microcolumn method and were found to range from 4.5–7.2 per cent (mean 5.2±0.82 S.D.). The haemoglobin level (Hb), mean corpuscular volume (MCV), plasma ferritin and HbA2 levels were measured on a further 299 cconsecutive Chinese pregnant women at a gestation of less than 24 weeks. 18 patients (6 per cent) had HbA2 level greater than 4.5 per cent and were diagnosed to be β-thalassaemic carriers. It was observed that all these patients had a MCV below 75 fl. If this level is selected in a screening procedure based on measurement of MCV alone all β-thalassaemia carriers could be detected and 11 per cent of the population screened would require HbA2 estimation. At a lower cut-off level of 70 fl, 8 per cent of the population screened wouid require HbA2 measurement (a decrease of 27 per cent) but the detection rate will be lowered considerably (83 per cent). The high false positive rate at all cut-off levels of MCV was largely due to the prevalence of iron deficiency anaemia in the population. Estimation of plasma ferritin level in patients with low MCV will reduce this false positive rate, but there will be a considerable delay in diagnosis in patients with concomitant iron deficiency and β-thalassaemia. The presence of iron deficiency in β-thalassaemia carriers did not reduce their HbA2 level below the diagnostic range in this study. Measurement of Hb level did not appear to be useful as a screening method since one third of the β-thalassaemia carriers had a Hb level over 11 g/dl. The validity of the MCV cut-off levels derived from the first part of the study was assessed in screening a larger population. 61 β-thalassaemia carriers (6 per cent) were detected out of 1166 patients screened. This incidence was not significantly different from the first part of the study. All these 61 patients had a MCV less than 75 ml. It was concluded that a two-step screening policy, based on MCV measurement followed by HbA2 estimation when the MCV value is less than 75 fl, is suitable for our population. It is efficient, straight forward with excellent sensitivity and required less time and effort for both laboratory staff and clinicians. 相似文献
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Twenty-six pregnant Chinese women who were at risk of giving birth to a fetus affected with homozygous α-thalassaemia-1 were examined serially by ultrasound. Six of these 26 pregnancies were affected. In one third of the affected pregnancies progressive fetal ascites appeared before 24 weeks gestation and these pregnancies were terminated. In the remaining two thirds abnormal estimated fetal weight-placental volume (EFW-PV) ratio and fetal growth retardation as evidenced by a falling biparietal diameter (BPD), femur length (FL) but a normal abdominal circumference (AC) was apparent by 28 weeks gestation. Increased transverse cardiac (TC) diameter was another consistent finding but appeared late. All these features appeared before the onset of fetal ascites. A normal EFW-PV ratio and fetal growth until 28 weeks gestation was a reassuring sign of normality. Abnormal EFW-PV ratio was the earliest sign to appear in affected pregnancies and a normal ratio until 28 weeks gestation had a 100 per cent predictive value. 相似文献
107.
Jyh-Hong Wu Ming-Shien Yen Chien-Wen Chen M. C. Kuo 《Journal of Polymers and the Environment》2016,24(4):318-327
Polylactide (PLA)/polymethylmethacrylate (PMMA)/α-cellulose composites were fabricated using a twin-screw extruder. During fabrication, α-cellulose short fibres were incorporated for improving the toughness of the brittle PLA and a chain extender was used for reducing PLA hydrolysis. Highly transparent PLA and PMMA were blended to obtain miscible and transparent blends. For evaluating the performance of the PLA/PMMA/α-cellulose composites, a series of measurements, including tensile and Izod impact tests, light transmission and haze measurements, thermomechanical analysis, and determination of isothermal crystallisation behaviour, was conducted. Adding the chain extender considerably reduced the occurrence of hydrolytic degradation. Both the chain extender and α-cellulose short fibres increased the elongation at break and Izod impact strength of the composites. Compared with the neat PLA, including 1.0 wt% α-cellulose short fibres increased the elongation at break and Izod impact strength of the composite PLA by approximately 211 and 219 %, respectively. According to the observed mechanical performance, the optimal blending ratios for PLA and PMMA were between 90:10 and 80:20. The total light transmittance of the composites was as high as 91 %, indicating that the PLA/PMMA blend was highly miscible. The haze value of the PLA/PMMA/α-cellulose composites was lower than 32 %. Incorporating cellulose short fibres increased the number of crystallisation sites and crystallinity of the PLA/PMMA/α-cellulose composites while reducing the spherulite dimensions. 相似文献
108.
Kin-Che Lam Weichun Ma Pak Kin Chan Wing Chi Hui King Lam Chung Yi-tak Teresa Chung Chun Yin Wong Hui Lin 《Environmental monitoring and assessment》2013,185(12):9683-9695
This paper reports on a study which explored the possible relationship between road traffic noisescape and urban form in Hong Kong. A total of 212 residential complexes from 11 contrasting urban forms were sampled, and their noise levels assessed both at dwelling and neighbourhood scales by noise mapping. Its findings indicate that residential complexes with different urban forms have significantly different noisescape attributes. There is a strong correlation between the noise characteristics and morphological indicators at the dwelling scale. A less obstreperous noisescape is associated with urban forms with lower road and building densities, and with building arrangements which provide self-noise screening. These findings suggest that urban form is an influential determinant of the noisescape in the urban environment, and they point to the need to rethink the conventional approach to managing the urban acoustic environment. 相似文献
109.
Niladri Basu Anton Scheuhammer Kirsti Rouvinen-Watt Nicole Grochowina Douglas Evans Hing Man Chan 《Environmental monitoring and assessment》2010,162(1-4):377-386
Studies are increasingly using cholinergic parameters as biomarkers of early neurotoxicity, but few have characterized this system in ecologically relevant model organisms. In the present study, key neurochemicals in the cholinergic pathway were measured and analyzed from discrete parts of brain and blood from captive mink (Mustela vison). Similar to other mammals, the regional distribution of cholinergic parameters in the brain could be ranked from highest to lowest as: basal ganglia > occipital cortex > brain stem > cerebellum (F 3,192?=?172.1, p?<?0.001). Higher variation in cholinergic parameters was found in the cerebellum (coefficient of variation = 34.9%), and the least variation was measured in the brain stem (19.7%). Variation was also assessed by calculating the difference between the lowest and highest measures among individual animals: choline acetyltransferase (1.6× fold difference), cholinesterase (2.0×), muscarinic receptor levels (2.4×), acetylcholine (3.7×), nicotinic receptor levels (3.9×), and choline transporter (5.0×). In blood samples, activity and inter-individual variation of cholinesterase was highest in whole blood and lowest in plasma and serum. By using captive mink of a common genetic source, age, gender, and rearing conditions, these data help establish normal levels, ranges, and variations of cholinergic biomarkers among brain regions, blood components, and individual animals. Such information may better enable the utility of cholinergic biomarkers in environmental assessments. 相似文献
110.
R. S. Oliveira Jr. W. C. Koskinen N. R. Werdin P. Y. Yen 《Journal of environmental science and health. Part. B》2013,48(1):39-49
Abstract The sorption of imidacloprid (l‐[(6‐chloro‐3‐pyridinyl)‐methyl]‐N‐nitro‐2‐imidazolid‐inimine) (IMI) and its metabolites imidacloprid‐urea (l‐[(6‐chloro‐3‐pyridinyl)‐methyl]‐2‐imidazol‐idinone) (IU), imidacloprid‐guanidine (l‐[(6‐chloro‐3‐pyridinyl)‐methyl]‐4,5‐dihydro‐lH‐imidazol‐2‐amine) (IG), and imida‐cloprid‐guanidine‐olefin ( 1 ‐[(6‐chloro‐3‐pyridinyl)methyl]‐lH‐imidazol‐2‐amine) (IGO) was determined on six typical Brazilian soils. Sorption of the chemicals on the soil was characterized using the batch equilibration method. The range and order of sorption (Kd) on the six soils was IG (4.75–134) > IGO (2.87–72.3) > IMI (0.55 ‐16.9) > IU (0.31–9.50). For IMI and IU, Kd was correlated with soil organic carbon (OC) content and CEC, the latter due to the high correlation between OC and cation exchange capacity (CEC) (R2=0.98). For IG and IGO, there was no correlation of sorption to clay, pH, OC or CEC due to the high sorption on all soils. Average Koc values were IU = 170, IMI = 362, IGO = 2433, and IG = 3500. Although Kd and Koc values found were consistently lower than those found in soils developed in non‐tropical climates, imidacloprid and its metabolites were still considered to be slightly mobile to immobile in Brazilian soils. 相似文献