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81.
Human neutrophils (polymorphonuclear leukocytes; PMN) respond to some CXC chemokines but do not migrate to CC chemokines. Recent work has shown that chemokine receptors can be modulated by inflammatory cytokines. In this study, the effect of IFN-gamma, a prototypic Th1 cytokine, on chemokine receptor expression in PMN was investigated. IFN-gamma caused a rapid (approximately 1 h) and concentration-dependent increase of CCR1 and CCR3 mRNA. The expression of CCR2, CCR5, and CXCR1-4 was not augmented. IFN-gamma-treated PMN, but not control cells, expressed specific binding sites for labeled monocyte-chemotactic protein (MCP)-3 and migrated to macrophage-inflammatory protein (MIP)-1alpha, RANTES, MCP-3, MIP-5/HCC2, and eotaxin. 7B11, a mAb for CCR3, inhibited the chemotactic response of IFN-gamma-treated PMN to eotaxin, and aminoxypentane-RANTES blocked PMN migration to RANTES. These results suggest that the selectivity of certain chemokines for their target cells may be altered by cytokines produced within an inflammatory context. Since PMN may play a role in orienting immunity toward Th1 responses, it is possible to speculate that IFN-gamma not only promotes Th1 differentiation directly, but also reorients the functional significance of Th2 effector cytokines by broadening the spectrum of their action to include PMN.  相似文献   
82.
Necrotizing enterocolitis (NEC) usually occurs in low birth weight infants who have had perinatal stress, and the mortality remains significant. There are a few reports of NEC in the postoperative period, especially in young infants. Nine neonates developed NEC following operations and form the basis of this report. The interval between operation and the diagnosis of NEC varied from 3 days to 4 mo. The surgical lesions included one case each of esophageal atresia, tetralogy of Fallot, supralevator rectal atresia with rectourethral fistula, and multiple intestinal atresias. Three babies had gastroschisis and two had "apple peel" intestinal atresia. Only 3 of the 9 survived. The usual clinical findings of NEC, abdominal distention, bile stained gastric residuals and diarrhea (with or without blood), can occur in the postoperative period without NEC and are, therefore, not reliable diagnostic signs. Significant changes in the clinical course of these babies occurred from 7 hr to 5 days before the diagnosis was established. In these patients the roentgen findings that established the diagnosis of NEC included intestinal ileus, pneumatosis intestinalis, and portal vein gas. Pneumatosis intestinalis and portal vein gas were the most reliable diagnostic signs, but appeared relatively late in the course of the disease. In one case pneumatosis was seen only in retrospect. None of the patients had definite pneumoperitoneum. Awareness of NEC as a potential postoperative complication may result in early recognition, treatment and survival.  相似文献   
83.
The aims of the current study were to synthesize new responsive polymeric microgels with embedded silver nanoparticles and then to employ these particles as catalyst for reduction reactions. To these ends, stimuli‐responsive microgels from PNIPAAm and the chitosan derivative were firstly synthesized by free radical precipitation polymerization. Then, silver nanoparticles were synthesized inside these microgel networks by in situ reduction of AgNO3. These microgels were temperature/pH sensitive with a phase transition temperature of 32–35 °C in water at pH = 3 and 8, respectively. The catalytic activity of the Ag nanoparticles for the reduction of 4‐nitrophenol can be tuned through the swelling or collapse of the responsive microgel network hosting the active nanoparticles.

  相似文献   

84.
Park SR  Mackay WG  Reid DC 《Water research》2001,35(6):1624-1626
Workers examining the transmission route(s) and reservoir(s) of infection for Helicobacter pylori have postulated several environmental reservoirs for the organism, including water. Such work has, to date, concentrated on the bulk liquid in drinking water systems rather than on biofilms. Previous investigations by the authors have suggested biofilms in water distribution systems are a possible reservoir of infection. This current study comprised of an analysis of a section of cast iron mains distribution pipe removed from an urban environment in the north-east of Scotland during routine maintenance work. Immediately upon removal of the pipe section, the interior lumen was swabbed to remove the biofilm layer. Subsequent analysis for the presence of Helicobacter DNA using a nested PCR approach produced a positive result. This data provides the first evidence for the existence of Helicobacter in biofilms found in water distribution systems anywhere in the world.  相似文献   
85.
Product development is a collaborative activity more often than ever carried out by distributed design teams. It is critical to determine how sketches are used in such environments in order to improve the design process. Sketches produced by students participating in a collaborative design project of three European Universities are classified according to the intention of the designer when producing a sketch, the level of detail shown in the sketch and the phase when the sketch was produced. The adapted classification system used in this paper helps to analyse type of sketches with most variety of ideas. Furthermore, this paper reviews which type of sketches offers the most potential to be further developed. Results show that persuasive sketches offer the broadest range of ideas since they are produced as a combination of ideas from brainstorming sessions. Shared sketches help to achieve consensus in decision-making since the sketches are most likely to be produced by the entire group rather than individually.  相似文献   
86.
87.
EU legislation requires a multimedia exposure assessment for substances supplied within the EU. Dietary intake is the main source of exposure for the majority of the population hence an essential component of the human risk assessment. This paper describes the available data for dietary copper and its use in estimating daily intake including variability and determinants of exposure. Typical and reasonable worst-case estimates are derived for the general population from the available peer reviewed literature. Intakes from drinking water are found to exhibit more variability than those from food. Therefore, different exposure scenarios are derived to reflect the range of acute and chronic exposures that may occur. Estimates of typical copper intakes for the EU population are in the range 0.8-1.8 mg/day. Typical copper intakes of men are higher than those of women while the intake among the general adult population is higher than that of the elderly. Intakes of both men and women are generally close to the WHO normative requirements but may be somewhat lower in specific locations where background levels of copper are unusually low. Alcoholic beverages represent minor contribution daily copper intakes. Intakes for children are rather variable ranging broadly from 0.7 to 1.5 mg/day and are somewhat age and sex dependent. Greater uncertainty applies to the assessment of local exposure incorporating food produced on land directly impacted by contemporary copper industry emissions. Specifically, the extent to which soil is enriched in copper in these conditions is unclear. However, effective homeostatic control mechanisms in plants limit uptake and transfer to the human food chain. A best estimate of 0.25 mg/day in addition to regional exposure was derived. Drinking water is estimated to contribute only marginally to total copper intake in most cases. Higher intakes may occur in areas of poor water quality and/or corroded distribution systems. Such elevated exposures appear unusual but their frequency is unknown.  相似文献   
88.
Significant β-glucanolysis takes place during mashing and is catalysed by a β-glucanase which is specific to mixed-linkage β-glucans. The enzyme develops during the germination of barley, but is rapidly and extensively destroyed in kilning. Partially-purified preparations of β-glucanase are protected from denaturation by heat if their solutions are adjusted to pH 4 or if bovine serum albumin is added. However the most effective stabiliser of the enzyme is reduced glutathione. Oligosaccharides containing three and four glucosyl units are produced by the action of β-glucanase and they are further converted during malting and mashing by a different enzyme(s) to disaccharides and glucose.  相似文献   
89.
The CSIRO Conditioning Oven has been developed for use in conditioning houses and testing laboratories that are concerned with the accurate determination of the invoice weight of consignments of wool. The primary objective of the oven design is to achieve a high degree of accuracy and reliability in accordance with the conditioning regulations of the International Wool Textile Organization (IWTO). For this reason, considerable care has been taken in the design of the oven chamber to ensure isothermal conditions during weighing and in the temperature control to ensure that the sample is dried at 105 ± 2°C. In addition, a fast drying rate is obtained by compressing the sample into a uniform bed and forcing the heated air through the sample under pressure.

Samples of scoured wool weighing up to 800 g can be dried in 10–15 min to a state corresponding to that laid down in the IWTO regulations.

A prototype oven has given satisfactory service in two years of operation by the Australian Wool Testing Authority.  相似文献   
90.
This paper describes part of a programme of worsted processing trials of wools prepared by objective clip preparation (OCP) in accordance with the Australian Clip Preparation Standards.

In each of four merino clips, chosen to cover the range of mean fibre diameter encountered in Australian merino wools, fleece wool prepared by OCP and by traditional methods was compared for processing performance. It is concluded that the variability of diameter of an OCP line is essentially the same as that of traditional lines classed from the same mob; that the properties of tops made from individual OCP lines are similar to those of tops made from traditional lines of the same mob, spinning performance and yarn characteristics being normal; and that, on average, the weight of card losses from OCP lines is the same as the combined weight of carding losses that would be obtained if the wool had been classed into quality-number lines and processed separately; a similar conclusion can be drawn for combing noil.  相似文献   
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