Pulmonary embolism.

Pulmonary embolism (PE) is an important health problem and often a major clinical challenge, not only because of the low specificity of its clinical manifestations but also because of the increasing number of medical circumstances that are risk factors for this illness and the importance of early identification, since prompt and appropriate treatment can decrease mortality from this disease by about 25%. In recent years research on PE has been extensive, directed mainly at trying to determine and characterize its risk factors, establish new clinical probability algorithms, develop new diagnostic methods and put existing ones into perspective, seek new therapeutic approaches (pharmacological and non-pharmacological), and above all establish protocols that can guide the clinician from the stage of clinical suspicion to measures to prevent recurrence. It was the authors' aim to review the most significant literature on this subject, in order to produce a text that reflects the state of the art concerning PE and that can be used as a guide in the clinical approach to this pathology.     

Absorption rates and free radical scavenging values of vitamin C-lipid metabolites in human lymphoblastic cells.

BACKGROUND: In this study we investigated the cellular absorption rates, antioxidant and free radical scavenging activity of vitamin C-lipid metabolites. The absorption was measured in a human lymphoblastic cell line using a spectrophotometric technique. MATERIAL/METHODS: Cellular vitamin C levels in the human lymphoblastic H9 cell line were measured using the 2,4-dinitrophenylhydrazine spectrophotometric technique. Free radical scavenging activity of vitamin C-lipid metabolites was measured by the reduction of 1,1-diphenyl-2-picryl hydrazyl (DPPH) to 1,1-diphenyl-2-picryl hydrazine. Vitamin C-lipid metabolite scavenging of peroxyl radical oxygen reactive species (ORAC) was determined by fluorescence spectrophotometry. RESULTS: Compared to ascorbic acid (AA), calcium ascorbate (CaA), and calcium ascorbate-calcium threonate-dehydroascorbate (Ester-C), vitamin C-lipid metabolites (PureWay-C) were more rapidly absorbed by the H9 human T-lymphocytes. The vitamin C-lipid metabolites (PureWay-C) also reduced pesticide-induced T-lymphocyte aggregation by 84%, while calcium ascorbate-calcium threonate-dehydroascorbate (Ester-C) reduced aggregation by only 34%. The vitamin C-lipid metabolites (PureWay-C) demonstrated free radical scavenging activity of nearly 100% reduction of DPPH at 20 microg/ml and oxygen radical scavenging of over 1200 micro Trolox equivalents per gram. CONCLUSIONS: These data demonstrate that the vitamin C-lipid metabolites (PureWay-C) are more rapidly taken-up and absorbed by cells than other forms of vitamin C, including Ester-C. This increased rate of absorption correlates with an increased protection of the T-lymphocytes from pesticide toxicities. Further, vitamin C-lipid metabolites (PureWay-C) are a potent antioxidant and have significant free radical scavenging capabilities.     

Genetic variability in the Guahibo population from venezuela

Four communities from Guahibo of Venezuela were analyzed for the genetic variants of nine erythrocyte enzymes and five serum proteins. Of the 14 loci determined, four were monomorphic. Significant frequency differentiation among communities, was present for ESD and TF markers. In general, Guahibo allele frequencies are in the variation ranges described for South American groups. The analysis indicates a relatively higher affinity of Guahibos with other Venezuelan groups within an irregular pattern of genetic distances that are likely related to the complex demographic history of the South American groups. Genetic diversity estimates reveal a moderate degree of genetic structure between the four Guahibo communities. This intra‐tribal variability in Guahibo appears to be lower than in Venezuelan Piaroa but higher than in other Amerindians and could be attributed to a combined effect of low population size and relative isolation of communities. At a continental level, the distribution of genetic diversity is consistent with preferential population movements along the eastern and western coastal areas. Am. J. Hum. Biol. 14:21–28, 2002. © 2002 Wiley‐Liss, Inc.     

Heparin effect on ionised calcium concentration

The effect of heparin on plasma ionised calcium was studied by adding it in increasing amounts to whole blood from 10 normal subjects. There was no significant change in ionised calcium from the addition of 1 U/ml but a significant fall of 0.02 mmol/1 when 2 U/ml were added and a progressive further fall with increasing concentrations. Heparin from three different manufacturers produced similar results. The effect of heparinisation in vivo was studied during regular haemodialysis on 10 patients with chronic renal failure. Following intravenous injection of 10000 U of heparin there was a consistent and significant fall averaging 0.03 mmol/l.     

Do weekly and fast-rotating shiftwork schedules differentially affect duration and quality of sleep?

 Characteristics of shiftwork schedules can have distinct impacts on workers’ sleep. This report presents comparisons of the effects of two different shiftwork schedules on duration and quality of the main sleep episodes in comparable worker populations at two different petrochemical plants. No significant differences were found for sleep duration in comparing the two plants. However, within each plant’s shift cycles, morning and night shifts showed shorter sleep durations than all other workdays and days off. Quality of sleep was perceived as lowest for night shifts of both plant schedules, and of lesser quality for weekly than for fast-rotating shifts. These results support recommendations for reducing the number of consecutive nights of shiftwork. However, before recommending any optimal shift schedule, interactions of sleep duration and quality with shift schedules need much further evaluation. Received: 18 December 1995/Accepted: 18 July 1996     

Carvedilol protects ischemic cardiac mitochondria by preventing oxidative stress.

Ischemia negatively affects mitochondrial function by inducing the mitochondrial permeability transition (MPT). The MPT is triggered by oxidative stress, which occurs in mitochondria during ischemia as a result of diminished antioxidant defenses and increased reactive oxygen species production. It causes mitochondrial dysfunction and can ultimately lead to cell death. Therefore, drugs able to minimize mitochondrial damage induced by ischemia may prove to be clinically effective. We analyzed the effect of carvedilol, a beta-blocker with antioxidant properties, on mitochondrial dysfunction. Carvedilol decreased levels of TBARS (thiobarbituric acid reactive substances), an indicator of oxidative stress, which is consistent with its antioxidant properties. Regarding cell death by apoptosis, although ischemia did increase caspase-8-like activity, there were no changes in caspase-3-like activity, which is activated downstream of caspase-8; this may indicate that the apoptotic cascade is not activated by 60 minutes of ischemia. We conclude that carvedilol protects ischemic mitochondria by preventing oxidative mitochondrial damage, and, by so doing, it may also inhibit the formation of the MPT pore.