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61.
BACKGROUND: Previously, we have shown that a premature stimulus can significantly modulate spatial gradients of ventricular repolarization (ie, modulated dispersion), which result from heterogeneous electrophysiological properties between cells. The role modulated dispersion may play in determining electrical instability in the heart is unknown. METHODS AND RESULTS: To determine if premature stimulus-induced changes in repolarization are a mechanism that governs susceptibility to cardiac arrhythmias, optical action potentials were recorded simultaneously from 128 ventricular sites (1 cm2) in 8 Langendorff-perfused guinea pig hearts. After baseline pacing (S1), a single premature stimulus (S2) was introduced over a range of S1S2 coupling intervals. Arrhythmia vulnerability after each premature stimulus was determined by measurement of a modified ventricular fibrillation threshold (VFT) during the T wave of each S2 beat (ie, S2-VFT). As the S1S2 interval was shortened to an intermediate value, spatial gradients of repolarization and vulnerability to fibrillation decreased by 51+/-9% (mean+/-SEM) and 73+/-45%, respectively, compared with baseline levels. As the S1S2 interval was further shortened, repolarization gradients increased above baseline levels by 54+/-30%, which was paralleled by a corresponding increase (37+/-8%) in vulnerability. CONCLUSIONS: These data demonstrate that modulation of repolarization gradients by a single premature stimulus significantly influences vulnerability to ventricular fibrillation. This may represent a novel mechanism for the formation of arrhythmogenic substrates during premature stimulation of the heart. 相似文献
62.
Uroporphyrinogen decarboxylase (URO-D) catalyzes the fifth step in the heme biosynthetic pathway, converting uroporphyrinogen to coproporphyrinogen by decarboxylating the four acetate side chains of the substrate. This activity is essential in all organisms, and subnormal activity of URO-D leads to the most common form of porphyria in humans, porphyria cutanea tarda (PCT). We have determined the crystal structure of recombinant human URO-D at 1.60 A resolution. The 40.8 kDa protein is comprised of a single domain containing a (beta/alpha)8-barrel with a deep active site cleft formed by loops at the C-terminal ends of the barrel strands. Many conserved residues cluster at this cleft, including the invariant side chains of Arg37, Arg41 and His339, which probably function in substrate binding, and Asp86, Tyr164 and Ser219, which may function in either binding or catalysis. URO-D is a dimer in solution (Kd = 0.1 microM), and this dimer also appears to be formed in the crystal. Assembly of the dimer juxtaposes the active site clefts of the monomers, suggesting a functionally important interaction between the catalytic centers. 相似文献
63.
RM Kaplan AM Navarro FG Castro JP Elder SI Mishra A Hubbell C Chrvala E Flores A Ramirez ME Fernandez-Esquer E Ruiz 《Canadian Metallurgical Quarterly》1996,12(6):467-471
BACKGROUND: The Healthy People 2000 report set the objective of increasing the percentage of women 40 or older who had ever received a mammogram and clinical breast examination to 80% by the year 2000. The report used a baseline of 36% for all American women and 20% for Hispanic women. The purpose of this study was to compare baseline estimates with data obtained in five Hispanic communities. METHODS: Common survey measures were administered in five studies participating in a National Cancer Institute Cooperative agreement. The surveys evaluated history of mammography in five Hispanic communities in the southwestern Unites States. RESULTS: Across the five communities, the rates of mammography use were significantly higher than the national baseline. Among women 40-49 years of age, 55% had completed mammography (95% confidence interval [CI] = 52%, 57%). Among women 50 years of age or older, 64% had received a mammogram (95% CI = 62%, 66%). Older women (above age 50) were significantly more likely to have completed the test than younger women (younger than age 50), and mammography was obtained less often among women who were uninsured and those who had lower levels of acculturation. CONCLUSIONS: We conclude that the rate of mammography use among Hispanic women has increased significantly over the last few years and that we are on track to reach the goal of 80% mammography compliance for Hispanic women 40 years and older by the year 2000. 相似文献
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65.
Nine pediatric patients with elbow-capsular contractures were treated by surgical release. Six patients had sustained prior trauma and three patients had medical conditions leading to capsular contracture. A lateral approach was used to release the anterior and posterior capsules, as well as to remove sites of bony impingement. All patients were treated with postoperative range of motion and splinting, with six patients receiving a continuous brachial plexus block to facilitate therapy. Average loss of extension improved from 47 to 15 degrees, mean angle of flexion from 102 to 124 degrees, and total arc of motion increased from 55 to 108 degrees at an average of 17 months after surgery. Complications included wound infection and catheter-site erythema. 相似文献
66.
PI Orlovski? VV Gritsenko FG Uglov SM Lazarev VV Davydenko KIu Senchik ON Bushmarin NP Galin AD Iukhnev VV Ziabrikov 《Canadian Metallurgical Quarterly》1998,157(1):10-16
This study presented the outcome of 92 EOC patients treated by platinum or platinum analogue with cyclophosphamide from January 1, 1993 to December 31, 1995. There were 77 evaluable patients. The follow-up ranged from 4-42 months (median 14 months). The over all 3-year survival was 64 per cent and the median progression-free interval was 16 months for the whole group. There was no significant difference in survival between patients who received cisplatin and those who received carboplatin (P = 0.093). Patients who underwent optimal debulking surgery had significantly longer progression-free interval (P = 0.001) than those who had sub-optimal surgery. Fifty four per cent of patients with clear cell carcinoma died of the disease. Patients who received cisplatin had a drop out rate while on therapy more often (24% vs 5.3%) than that of carboplatin. Toxicities from chemotherapy were moderate but manageable. 相似文献
67.
DM Dougherty JL Steinberg AA Wassef D Medearis DR Cherek FG Moeller 《Canadian Metallurgical Quarterly》1998,79(3):255-265
In an exploratory study, 10 schizophrenic patients and 10 normal control subjects performed immediate and delayed memory tasks, which were variants of previously developed continuous performance tests. Both tasks required participants to identify five-digit numbers which were repeated. Numbers were presented in series for 500 ms each and separated by a 500-ms time-out period. In the immediate memory task, subjects were to respond if a number was identical to the one that had immediately preceded it. The delayed memory task differed from the first task in that a longer delay (3.5 s) between stimuli was introduced, and during this delay distracter stimuli appeared. While normal control subjects performed accurately on both tasks (exceeding 80% correct detections), schizophrenic patients performed poorly, performing worse on the delayed memory task than on the immediate memory task. Rates of commission errors (responses made to similar, but not identical numbers) were nearly equal between groups on the immediate memory task, but on the delayed memory task normal control subjects made relatively more commission errors while schizophrenic patients made fewer commission errors. No differences in response latencies were observed between subject groups or tasks. This paradigm may prove useful in discriminating subtle differences in immediate and delayed memory capability among psychiatric populations and normal control subjects. 相似文献
68.
FG Roberge MD de Smet J Benichou MF Kriete J Raber J Hakimi 《Canadian Metallurgical Quarterly》1998,82(10):1195-1198
AIM: To evaluate the anti-inflammatory cytokine interleukin-13 (IL-13) for the treatment of uveitis. METHODS: Uveitis was induced in monkeys by immunisation with human retinal S-antigen. Starting at the onset of disease, the animals were treated with IL-13 at 25 micrograms/kg, or vehicle control, injected subcutaneously once a day for 28 days. Intraocular inflammation was scored by indirect ophthalmoscopy for a period of 56 days. Circulating leucocyte levels were monitored. RESULTS: Uveitis started unilaterally in all but one animal. IL-13 inhibited inflammation both in the eyes in which the disease was present when the treatment was initiated (p = 0.0001), and in the contralateral initially negative eyes (p = 0.0001). After cessation of therapy, there was a progressive increase of inflammation in the IL-13 treated group. However, the beneficial effect of IL-13 extended into the 4 week follow up period. IL-13 produced an increase in circulating polymorphonuclear neutrophils and a decrease in lymphocytes. CONCLUSION: Administration of IL-13 appears to be a promising modality of treatment for severe uveitis. 相似文献
69.
70.
TF Martínez FJ Moyano M Díaz FG Barroso FJ Alarcn 《Journal of the science of food and agriculture》2004,84(14):1979-1987
The inefficiency of protein utilisation by ruminants fed protein concentrates (based on legume meals) causes serious economic loss and environmental damage owing to their rapid hydrolysis and deamination in the rumen. Thus efforts aimed at slowing the ruminal fermentation of such feeds are needed, and recent studies have observed potentially positive effects of tannins on ruminant nutrition under certain circumstances. Tannins are a complex group of naturally occurring plant polyphenols characterised by their ability to bind with proteins. This property of tannins is considered responsible for the decreased ruminal digestibility of forages both in vivo and in vitro. Under that perspective, commercial tannic acid was added at three proportions (10, 25 and 50 g kg?1 on a dry matter basis) to four different legume meals (horse bean, kidney bean, soybean and pea), and the effect on in situ dry matter and crude protein ruminal disappearance was assessed. The results confirmed the dose‐dependent (although not persistent after 48 h) slowing of in situ digestibility, this effect being significant at the highest tannin treatment when compared with untreated samples. Scanning electron microscopy revealed that soybean seed endosperm cell walls were protected from digestion by the ruminal microbiota, while the digestion of starch granules was relatively unaffected by tannic acid. Electrophoresis of the protein fractions confirmed the lower digestibility of tannin‐treated seeds as well as the relative lack of alteration of the electrophoretic profile of individual proteins. Implications for the digestion of concentrates in ruminants are discussed. Copyright © 2004 Society of Chemical Industry 相似文献