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871.
Research on the toxicity of arsenic has focused on sublethal effects that do not provide sufficient information for risk estimation. While most studies have focused on organism response to constant arsenic exposures, organisms in nature are exposed to fluctuating As concentrations. Consequently, results obtained from standardized bioassays with constant exposures may not adequately characterize risk to indigenous biota. This research was designed to characterize the response of Daphnia magna to fluctuating arsenic exposures during 21-day experiments. At concentrations > or =3000 microg/L As, 21-day pulsed exposure mortality increased as a function of exposure concentration and duration. In addition, 21-day pulsed exposure mortality increased with increasing recovery time. Pulsed As exposure did not affect the growth of D. magna over 21 days. Twenty-one day accumulative reproduction of D. magna was only affected by pulsed exposures of high As concentration and long durations. 相似文献
872.
Rogevich EC Hoang TC Rand GM 《Archives of environmental contamination and toxicology》2009,56(3):450-458
Florida apple snails (Pomacea paludosa) were exposed to three concentrations of copper (Cu), in water (8 μg/L, 16 μg/L, 24 μg/L), for one generation to examine
uptake and the effects on survival, growth, and reproduction of the F0 generation and survival, growth, and whole body Cu of the F1 generation. During a 9-month Cu exposure, apple snails exposed to 8–16 μg/L Cu had high Cu accumulation (whole body, foot,
viscera, and shell) and significantly reduced clutch production (8–16 μg/L) and egg hatching (16 μg/L). Apple snails exposed
to the 24 μg/L Cu had low survival and the treatment was therefore terminated. Concentrations of minerals (Na+, K+, Mg2+, Ca2+) in tissues were maintained regardless of Cu exposure, but the distribution of Cu in the body of snails differed, depending
on exposure concentrations. Higher exposure concentrations resulted in a greater percentage of Cu accumulated in the viscera
of the snail. Copper exposure to the F0 generation did not affect the survival, growth, or whole body Cu concentrations in the F1 generation. These finding are significant, given the importance of the Florida apple snail in the Everglades food chain.
Changes in the abundance of apple snail populations, as a result of Cu exposure, could ultimately affect foraging success
of predators. 相似文献
873.
Angiogenesis refers to growth of blood vessels from pre-existing ones. In 1971, Folkman proposed that by choking off the blood supply to tumors, they are starved, leading to their demise. A few years ago, the monoclonal antibody Avastin became the first antiangiogenic biological approved by FDA, for treatment of cancer patients. Two other antiangiogenic endogenous protein fragments were isolated in Folkman's laboratory more than a decade ago. Here, we present a short review of data demonstrating that angiostatin and endostatin display a biphasic antitumor dose-response. This behavior is common among a large number of antiangiogenic agents and the reduced effectiveness of antiangiogenic agents at high dose rates may be due to suppression of growth of new vessels carrying the agent into the critical region around the tumor. 相似文献
874.
875.
Percutaneous endoscopic gastrostomy sites infected by methicillin-resistant Staphylococcus aureus: impact on outcome 总被引:3,自引:0,他引:3
BACKGROUND: The impact of methicillin-resistant Staphylococcus aureus (MRSA) colonization of percutaneous endoscopic gastrostomy (PEG) sites on morbidity and mortality is uncertain. AIM: We investigated the impact of known prior MRSA colonization on the incidence of symptomatic PEG site wound infection and mortality. METHODS: Consecutive patients who had PEG tubes inserted recently at our hospital were identified. The presence or absence of MRSA colonization before PEG placement was noted. Patients were observed for wound infection, and swabs were taken from the site if there was clinical infection. Mortality within 30 days of PEG placement was determined. RESULTS: A total of 83 patients underwent PEG placement; 23 (28%) of these patients had known MRSA colonization before PEG placement. Of these, 13 (57%) developed symptomatic MRSA infection of the PEG site. The remaining 60 patients (72%) had no known prior MRSA colonization. In these patients, 9 (15%) developed symptomatic MRSA infection of the PEG site. The overall incidence of wound infection was 37% (31) of the total undergoing PEG placement, of whom 71% (22) had developed MRSA infection. The mortality of those with symptomatic MRSA infection of the PEG site was 9% (2/22), whereas the mortality from non-MRSA-infected PEGs was 20% (12/61). CONCLUSION: Patients with prior MRSA colonization had a significantly higher risk of developing symptomatic MRSA infection of the PEG site. However, there was still a significant risk (15%) of developing MRSA infection of the PEG site for patients with no known prior MRSA infection. MRSA infection of the PEG site did not affect mortality. 相似文献
876.
Gerasimos Tzortzatos Ofra Wers?ll Kristina Gemzell Danielsson Annika Lindblom Emma Tham Miriam Mints 《Hereditary cancer in clinical practice》2014,12(1):14
Background
Uterine cancer (UC) represents 5.1% of all female malignancies in Sweden. Accumulation of UC in families occurs in around 5% of cases. We wanted to identify any familial association between UC and other selected cancers and to study the frequency of Lynch,Cowden and cancer syndromes among consecutive UC patients in Sweden.Methods
481 UC patients were included. Information on the cancer diagnoses of their relatives (first- (FDRs) and second-degree (SDRs) relatives and first cousins) was obtained. The relative frequencies of different cancers among relatives were compared to those in the Swedish general cancer population in 1970 and 2010. Families that fulfilled the criteria for hereditary cancer syndromes were tested for mutations in the causative genes. Families with at least one case of UC in addition to the index patient were compared to families with no additional cases to investigate possible characteristics of putative hereditary cancer syndromes.Results
There was an increased prevalence of UC in our study population compared to the Swedish general cancer population in 1970 and 2010 (6% vs. 4% and 3%, respectively). Seven families had Lynch Syndrome according to the Amsterdam II criteria. No families fulfilled the criteria for Cowden syndrome. In total 13% of index patients had at least one relative with UC and these families tended to have more cases of early onset cancer among family members. In addition, 16% of index patients were diagnosed with at least one other cancer. No families fulfilled the criteria for Cowden syndrome.Conclusion
We showed a familial clustering of UC among relatives of our index patients. Of the seven families with mutation-verified Lynch Syndrome, only one had been previously diagnosed, highlighting the need to increase gynecologists’ awareness of the importance of taking family history. Our data on multiple cancers and young age of onset in families with uterine cancer is compatible with the existence of additional hereditary uterine cancer syndromes.877.
Melodi Yong MBChB Edward Liu BHSc MD Richard Tee MBBS PhD Xin Zhang BEng PhD Stephen Tham MBBS 《ANZ journal of surgery》2023,93(6):1652-1657
Background
Surgical fixation of scaphoid fractures may result in unrecognized screw protrusion and subsequent cartilage damage to the adjacent joints. The purpose of this study was to use a three-dimensional (3D) scaphoid model to determine the wrist and forearm positioning that will allow intra-operative fluoroscopic visualization of screw protrusions.Methods
Two 3D scaphoid models, with the wrist in neutral and 20° ulnar deviated, were reconstructed from a cadaveric wrist using the Mimics software. The scaphoid models were divided into three segments and further divided into four quadrants in each of the three segments along the scaphoid axes. Two virtual screws, with a 2 and 1 mm groove from the distal border, were placed so that the screws protrude from each quadrant. The wrist models were rotated along the long axis of the forearm and the angles at which the screw protrusions were visualized were recorded.Results
One-millimetre screw protrusions were visualized at a narrower range of forearm rotation angles compared to 2 mm screw protrusions. One-millimetre screw protrusions in the middle dorsal ulnar quadrant could not be detected. Visualization of the screw protrusion in each quadrant varied with forearm and wrist positioning.Conclusion
In this model, all screw protrusions, except 1 mm protrusions in the middle dorsal ulnar quadrant, were visualized with the forearm in pronation, supination or in the mid-pronation position and with the wrist in neutral or 20° ulnar deviated. 相似文献878.
Jason C. Yam Xiu Juan Zhang Ka Wai Kam Li Jia Chen Clement C. Tham Chi Pui Pang 《Ophthalmic & physiological optics》2023,43(3):299-310
The purpose of this study was to explore the findings from the Hong Kong Children Eye Study and the Low Concentration Atropine for Myopia Progression (LAMP-1) Study. The incidence of myopia among schoolchildren in Hong Kong more than doubled during the COVID-19 pandemic, with outdoor time decreased significantly and screen time increased. The change in lifestyle during the COVID-19 pandemic aggravated myopia development. Low-concentration atropine (0.05%, 0.025% and 0.01%) is effective in reducing myopia progression with a concentration-related response. This concentration-dependent response was maintained throughout a 3-year follow-up period, and all low concentrations were well tolerated. An age-dependent effect was observed in each treatment group with 0.05%, 0.025% and 0.01% atropine. Younger age was associated with a poor treatment response to low-concentration atropine. Additionally, low-concentration atropine induced choroidal thickening along a concentration-dependent response throughout the treatment period. During the third year, continued atropine treatment achieved a better effect across all concentrations compared with the washout regimen. Stopping treatment at an older age and receiving lower concentration were associated with a smaller rebound effect. However, differences in the rebound effect were clinically small across all the three concentrations studied. 相似文献
879.
Kwang Wei Tham Rohana Abdul Ghani Sioksoan C. Cua Chaicharn Deerochanawong Mia Fojas Samantha Hocking June Lee Tran Quang Nam Faruque Pathan Banshi Saboo Sidartawan Soegondo Noel Somasundaram Alice M. L. Yong John Ashkenas Nicola Webster Brian Oldfield 《Obesity reviews》2023,24(2):e13520
Obesity is a chronic disease in which the abnormal or excessive accumulation of body fat leads to impaired health and increased risk of mortality and chronic health complications. Prevalence of obesity is rising rapidly in South and Southeast Asia, with potentially serious consequences for local economies, healthcare systems, and quality of life. Our group of obesity specialists from Bangladesh, Brunei Darussalam, India, Indonesia, Malaysia, Philippines, Singapore, Sri Lanka, Thailand, and Viet Nam undertook to develop consensus recommendations for management and care of adults and children with obesity in South and Southeast Asia. To this end, we identified and researched 12 clinical questions related to obesity. These questions address the optimal approaches for identifying and staging obesity, treatment (lifestyle, behavioral, pharmacologic, and surgical options) and maintenance of reduced weight, as well as issues related to weight stigma and patient engagement in the clinical setting. We achieved consensus on 42 clinical recommendations that address these questions. An algorithm describing obesity care is presented, keyed to the various consensus recommendations. 相似文献