Resuscitation preferences among patients with severe congestive heart failure: results from the SUPPORT project. Study to Understand Prognoses and Preferences for Outcomes and Risks of Treatments

BACKGROUND: Previous studies have shown wide variation in plasma dexamethasone (DEX) concentrations following a standard 1-mg dexamethasone suppression test (DST), and significantly lower DEX concentrations in DST nonsuppressors compared with suppressors, suggesting that DEX pharmacokinetics/bioavailability is an important variable associated with DST nonsuppression. METHODS: To determine the effect of plasma DEX levels on the DST in Chinese depressives, we measured plasma DEX and post-DEX cortisol levels at 4:00 PM in a group of 50 depressed outpatients, 28 anxiety outpatients, and 33 normal subjects during the course of 1-mg oral overnight DST. RESULTS: We found a significant difference in the plasma DEX levels between DST nonsuppressors and suppressors in the depression group and overall subject population, and a significant negative correlation between the plasma DEX and cortisol levels in the depression, anxiety, and total groups. Within a DEX "window", the DST performance was enhanced, whereas the relationships between plasma DEX and post-DEX cortisol levels remained equally strong. CONCLUSIONS: Our findings support a relationship between plasma DEX and post-DEX cortisol levels, a relationship that might be superimposed on the hypothalamic-pituitary-adrenal axis. Comparing our "window" range with those of previous studies, we suggest that Chinese depressives may have lower limits of plasma DEX window, and that ethnicity may be an intervening variable in both DST response and pharmacokinetics of DEX.     

Successful long-term kidney-pancreas transplants in diabetic patients with high C-peptide levels

Health Canada and the Canadian-Italian Physicians Association recently spent $20,000 to send 4 Canadian cancer specialists to Italy to check out the "miracle" anticancer cocktail prepared by an Italian physician. Most doctors remain decidedly sceptical about this latest "cure," but Charlotte Gray says their suspicions count for little when an issue like this captures the imagination of the public and their politicians.     

Reduced mechanical efficiency in chronic obstructive pulmonary disease but normal peak VO2 with small muscle mass exercise

We studied six patients with chronic obstructive pulmonary disease (COPD) (FEV1 = 1.1 +/- 0.2 L, 32% of predicted) and six age- and activity level-matched control subjects while performing both maximal bicycle exercise and single leg knee-extensor exercise. Arterial and femoral venous blood sampling, thermodilution blood flow measurements, and needle biopsies allowed the assessment of muscle oxygen supply, utilization, and structure. Maximal work rates and single leg VO2max (control subjects = 0.63 +/- 0.1; patients with COPD = 0.37 +/- 0.1 L/minute) were significantly greater in the control group during bicycle exercise. During knee-extensor exercise this difference in VO2max disappeared, whereas maximal work capacity was reduced (flywheel resistance: control subjects = 923 +/- 198; patients with COPD = 612 +/- 81 g) revealing a significantly reduced mechanical efficiency (work per unit oxygen consumed) with COPD. The patients had an elevated number of less efficient type II muscle fibers, whereas muscle fiber cross-sectional areas, capillarity, and mitochondrial volume density were not different between the groups. Therefore, although metabolic capacity per se is unchanged, fiber type differences associated with COPD may account for the reduced muscular mechanical efficiency that becomes clearly apparent during knee-extensor exercise, when muscle function is no longer overshadowed by the decrement in lung function.     

Time-Constrained Scheduling of Weighted Packets on Trees and Meshes

Abstract. The time-constrained packet routing problem is to schedule a set of packets to be transmitted through a multinode network, where every packet has a source and a destination (as in traditional packet routing problems) as well as a release time and a deadline. The objective is to schedule the maximum number of packets subject to deadline constraints. This problem is studied in [1], where it is shown that the problem is NP-Complete even when the underlying topology is a linear array. Approximation algorithms are also provided in [1] for the linear array and the unidirectional ring for both the case where packets may be buffered in transit and the case where they may not be. In this paper we extend the results of [1] in two directions. First, we consider the more general network topologies of trees and two-dimensional meshes. Second, we associate with each packet a measure of utility, called a weight, and study the problem of maximizing the total weight of the packets that are scheduled subject to their timing constraints. For the bufferless case, we provide constant factor approximation algorithms for the time-constrained scheduling problem with weighted packets on trees and meshes. We also provide logarithmic approximations for the same problems in the buffered case. These results are complemented by new lower bounds, which demonstrate that we cannot hope to achieve the same results for general network topologies. For example, we show that if k packets are required to follow prescribed paths in an arbitrary graph, then unless NP = ZPP, there is no polynomial-time k ^1-ε -approximation, for any ε > 0 , to the optimal set of packets that can be scheduled.     

Holes in Starch Granules: Confocal,SEM and Light Microscopy Studies of Starch Granule Structure

Following an initial observation of putative holes within potato starch granules during observation in a medium with the same refractive index, the internal architecture of starch granules has been investigated using confocal, scanning electron and light microscopy. These complimentary microscopy techniques confirmed the existence of holes at the hilum of potato, rice and wheat starch granules. Observations were made with minimal sample preparation to avoid the generation of artifactual holes. Using image analysis we have quantitatively measured the occurrence and the size distribution of holes and linked their appearance to the drying of the granule.     

Identification of microsatellite markers near the human ob gene and linkage studies in NIDDM-affected sib pairs

Non-insulin-dependent diabetes mellitus (NIDDM) is a complex metabolic disorder with a significant genetic component. Obesity is a frequent complicating factor for NIDDM. In the mouse, a number of single gene defects that result in obesity have been described. Mutations in one of these genes, the ob gene, results in both obesity and NIDDM. Recently, the cloning of the murine ob gene and its human homologue has been reported (Nature 372:425-432, 1994). In the present study, the contribution of genetic variation at the human ob locus to NIDDM susceptibility was assessed by analyzing allele sharing in NIDDM-affected sib pairs (ASPs) for markers located near the human ob gene. Four yeast artificial chromosome clones containing the human ob gene were isolated. These clones colocalized the ob gene and two microsatellite markers, D7S514 and D7S635, to a region of 280 kb on the long arm of human chromosome 7. The microsatellite markers were typed in 346 Mexican-American NIDDM-ASPs derived from 176 families and an additional 110 ethnically and geographically matched controls. No evidence of linkage or association between either microsatellite marker and NIDDM was observed in this population. These results suggest genetic variation in the human ob gene does not play a major role in susceptibility to NIDDM in Mexican-Americans.     

Self-interruptions in discretionary multitasking

Human multitasking is often the result of self-initiated interruptions in the performance of an ongoing task. These self-interruptions occur in the absence of external triggers such as electronic alerts or email notifications. Compared to externally induced interruptions, self-interruptions have not received enough research attention. To address this gap, this paper develops a typology of self-interruptions based on the integration of Flow Theory and Self-regulation Theory. In this new typology, the two major categories stem from positive and negative feelings of task progress and prospects of goal attainment. The proposed classification is validated in an experimental multitasking environment with pre-defined tasks. Empirical findings indicate that negative feelings trigger more self-interruptions than positive feelings. In general, more self-interruptions result in lower accuracy in all tasks. The results suggest that negative internal triggers of self-interruptions unleash a downward spiral that may degrade performance.     

Natural honey prevents ischaemia-reperfusion-induced gastric mucosal lesions and increased vascular permeability in rats

OBJECTIVE: It has been proposed that natural honey may contain a 'sucralfate-like' substance. Recent studies have shown that sucralfate affords protection against ischaemia-reperfusion-induced injuries in the rat stomach. Therefore, the effect of honey was studied on ischaemia-reperfusion-induced gastric lesions, intraluminal bleeding, vascular permeability and non-protein sulphhydryls (NP-SH) in the rat stomach. METHODS: Rats were subjected to 30 min of gastric ischaemia in the presence of 100 mM HCl and reperfusion period of 60 min. Intraluminal bleeding was assessed macroscopically and the gastric lesions were graded microscopically under an inverted microscope. Vascular permeability was quantified by measuring spectrophotometrically the extravasated Evans blue dye in the stomach. NP-SH levels were measured spectrophotometrically. A luminol-dependent chemiluminescence method was used to assess antioxidant effects of honey in vitro. RESULTS: There were significantly more gastric lesions, more severe intraluminal bleeding, more leakage of Evans blue and depletion of NP-SH during the reperfusion period as compared to controls. Pre-treatment with honey (0.078-0.625 g/kg, orally) or dimethyl sulphoxide (0.02-0.08 g/kg, intraperitoneally) 30 min before the ischaemia-reperfusion dose-dependently reduced the gastric lesions and intraluminal bleeding and decreased the vascular permeability. Furthermore, honey reversed the ischaemia-reperfusion-induced depletion of NP-SH levels and inhibited the luminol-dependent chemiluminescence induced in a cell-free xanthine-xanthine oxidase system. CONCLUSION: These results suggest that gastric protection by honey may be a result of its antioxidant effect. It is suggested that this property of honey may be due to the presence of a 'sucralfate-like' substance.