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81.
A screening level probabilistic risk assessment of mercury in Florida Everglades food webs 总被引:4,自引:0,他引:4
A screening level probabilistic assessment of risks was performed on three species of piscivorous wildlife at the top of Everglades aquatic food webs: the American alligator (Alligator mississippiensis), the great egret (Egretta alba), and the raccoon (Procyon lotor varius). Ranges of dietary exposure concentrations (and probability distribution functions) were derived for two general areas of the Everglades: Shark Slough and the southcentral Everglades (highly contaminated with Hg), and the northern Everglades (a lower Hg contaminated area in and near Water Conservation Area 1). Ranges of toxicity reference values and probability distribution functions were derived from literature on the toxicity of dietary methyl Hg to birds and mammals. Probability distributions of risk estimates for each receptor were generated using Monte Carlo simulations and indicated that piscivorous wildlife feeding in the south-central region of the Everglades are at high risk from consumption of Hg-contaminated prey. Alligators had 100% exceedences of chronic risk thresholds, and great egrets had 99% exceedences. In the northern Everglades, exceedences of chronic risk thresholds were substantially lower but were still present (6-34% exceedences). Results support previous studies suggesting that top predators of the Everglades may be at risk from Hg contamination and indicate that Hg risks are location-dependent. 相似文献
82.
Human papilloma virus infection (condyloma) of the cervix and cervical intraepithelial neoplasia: a histopathologic and statistical analysis 总被引:1,自引:0,他引:1
C P Crum K Egawa B Barron C M Fenoglio R U Levine R M Richart 《Gynecologic oncology》1983,15(1):88-94
Two hundred fifty consecutive cases previously diagnosed as advanced intraepithelial neoplasia (CIN 2 and CIN III) were reviewed and examined for the presence of coexisting condyloma. When the mean ages and age distributions were analyzed, there was a consistent shift of the age distribution to a younger age among women with CIN and condyloma as opposed to CIN alone. Furthermore, when the relationship between age and case accumulation was normalized from a curvilinear to a linear relationship, there were significant differences in the slope of the accumulation rate between cohorts of CIN III with and without condyloma. These differences suggest that the concordant observation of both lesions in a given patient is not a random process resulting from two independent events but rather indicates an underlying dependence between the two (i.e., condyloma and CIN). It cannot, however, be determined statistically whether the associated condyloma is directly responsible for the CIN lesion or hastens its transit time. 相似文献
83.
Spirulina has been used in a variety of practical applications in biotechnology and medical sciences. This paper presents the antiviral activity found in a hot water extract (HWE) of a commercial preparation of Spirulina maxima, studied by a microplate inhibition assay, using several viruses. The HWE inhibited the infection for: herpes simplex virus type 2 (HSV-2), pseudorabies virus (PRV), human cytomegalovirus (HCMV), and HSV-1, and the 50% effective inhibition doses (ED(50)) were 0.069, 0.103, 0.142, and 0.333 mg/ml for each virus, respectively. For adenovirus the inhibition was less than 20%, and no inhibition was found for measles virus, subacute sclerosing panencephalitis virus (SSPE), vesicular stomatitis virus (VSV), poliovirus 1 and rotavirus SA-11, at concentrations of 2 mg/ml of the HWE. The highest antiviral activity was for HSV-2, with a selectivity index of 128. The antiviral activity was not due to a virucidal effect. Herpesvirus infection was inhibited at the initial events (adsorption and penetration) of the viral cycle. To initiate the isolation and identification of the compound that exhibits the antiviral activity of S. maxima, some extracts made by using several solvents with different polarity were evaluated by microplate inhibition assay using HSV-2. The highest antiviral activity was detected in the methanol-water 3:1, which suggests that the antiviral activity is probably due to highly polar compounds. 相似文献
84.
Role of primary afferents in spinal cord stimulation-induced vasodilation: characterization of fiber types 总被引:2,自引:0,他引:2
Selected patients with peripheral vascular disease can be treated with spinal cord stimulation (SCS) to improve blood flow in the limbs. However, the mechanisms producing these effects remain unclear. The present study was designed to investigate if SCS produces cutaneous vasodilation via antidromic activation of the unmyelinated C-fibers and/or the small myelinated fibers. SCS was applied to anesthetized rats with a ball electrode at the L2-L3 spinal level. In Protocol 1, effects of capsaicin were examined. Blood flow changes in the hindpaw induced by SCS were measured in the footpad with laser Doppler flowmeters. Topical application of capsaicin (1%) on the tibial nerve did not affect SCS-induced vasodilation at 30 and 60% of motor threshold (MT). However, the duration of vasodilation induced by SCS at 90% MT and at 10 times MT was significantly reduced after capsaicin application on the tibial nerve. In Protocol 2, antidromic compound action potentials (CAPs) of the tibial nerve were recorded in response to SCS. CAPs of the large and the small myelinated afferent fibers were observed in response to SCS at all intensities. However, even with SCS at ten times MT, CAPs of C-fibers could not be detected in the tibial nerve. In Protocol 3, antidromic CAPs of the dorsal root were measured in response to SCS. Antidromic CAPs of C-fibers in dorsal roots were evoked by SCS at >or=90% of MT. It is concluded that SCS-induced vasodilation at or=90% of MT may also involve antidromic activation of some unmyelinated C-fibers. 相似文献
85.
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88.
Barron DJ Etherington PJ Winlove CP Jarvis JC Salmons S Pepper JR 《The Annals of thoracic surgery》2001,71(3):852-861
BACKGROUND: Atrophy and fibrosis of the distal part of the latissimus dorsi muscle (LDM) wrap is a recognized complication of cardiomyoplasty that has been attributed to ischemia. Failure of the muscle wrap contributes to the late attrition seen in clinical cardiomyoplasty. In this study we examined the role of two-staged mobilization and of preconditioning by electrical stimulation on the regional perfusion and oxygenation of the LDM. METHODS: In a rabbit model (n = 36) the LDM was preconditioned as follows: group A muscles received preconditioning in situ; group B muscles were partially mobilized by dividing the intercostal perforators and then preconditioned; and group C muscles were completely mobilized and wrapped around a silicone-rubber mandrel before conditioning. Controls received no conditioning. The preconditioning regimen consisted of 2 weeks of continuous stimulation at 2.5 Hz. At completion of preconditioning the muscles were fully mobilized and mounted on a muscle-testing apparatus. Purpose-built microelectrodes measured regional PO2 and perfusion using a diffusible gas tracer technique. Muscles were weighed and processed for fiber typing and capillary counting. RESULTS: All preconditioned muscles demonstrated fiber transformation, with increased fatigue resistance. Perfusion of preconditioned muscles both at rest and during contraction was higher than control in the proximal part of the muscle. Distal regions of group B muscles had higher perfusion and capillary density than any other group (p < 0.05). Distal regions of group C had the lowest perfusion and capillary density, and showed muscle atrophy and histologic evidence of necrosis. During fatigue testing there was a decrease in the PO2 in the distal regions of the control and group C muscles (p < 0.05), whereas it was maintained at resting levels in both group A and B muscles. CONCLUSIONS: Conditioning in situ improves perfusion of the distal LDM and prevents a fall in tissue PO2 during contraction. Two-stage mobilization further improves distal perfusion and capillary density. In contrast, shortterm elevation followed by conditioning produces impaired distal perfusion, decrease in PO2, and fiber necrosis in the distal muscle. The present study suggests that partial mobilization of the LDM performed at the same time as placement of electrodes for preconditioning may prepare the LDM better for the demands of cardiomyoplasty. 相似文献
89.
90.
Barron MA Duncan DS Green GJ Modrusan D Connolly B Chait P Saunders EF Greenberg M 《Medical and pediatric oncology》2000,34(3):177-182
BACKGROUND: The treatment of malnutrition, which is of great concern in paediatric haematology/oncology patients, is fraught with problems. The goals of our study were to document the complications and assess the weight gain with gastrostomy tubes (G-tubes) in this population. PROCEDURE: Patient data were acquired by retrospective review of all haematology, oncology, and bone marrow transplant (BMT) patients (n = 44) who received radiologically placed G-tubes at our institution over a 4-year period. RESULTS: Forty-four G-tubes were placed (59% peri-BMT). At tube placement, 55% of patients were malnourished and 45% were nourished. Seventy-five percent of patients had the procedure without general anaesthetic. Localized G-tube-site infection was the most common complication (41%). Major complications occurred in 3 patients; 2 patients experienced localized peritonitis, and 1 patient developed a localized collection of pus in the abdominal wall. There were no G-tube-related deaths. At 1 month after the tube insertion, 39% of patients had gained, 54% maintained, and 7% lost weight. At 3 months, 69% had gained, 28% maintained, and 3% lost weight. There was a statistically significant weight gain from the time of the G-tube placement to both 1 month (P < 0.018) and 3 months (P < 0.0001) after G-tube placement. Patients in all diagnosis categories showed improvement from 1 to 3 months. CONCLUSIONS: We conclude that retrograde tube placement is safe and can frequently be done without general anaesthetic and that G-tube feeding effectively reverses malnutrition and prevents weight loss in this patient population. 相似文献