Mild mental stress in diabetes: changes in heart rate and subcutaneous blood-flow

Summary. A TV-game of tennis of 20 min duration was used to study the influence of mild mental stress on subcutaneous blood-flow (SBF), blood-pressure and heart rate in nine insulin-dependent diabetics and nine healthy subjects. SBF was measured on the thigh by local clearance of xenon-133. Measurements were made before, during and after the period of stress. During stress, SBF increased significantly by 26% in the healthy subjects, while SBF remained unchanged in the diabetics. The difference between the two groups was significant (P<0–05). Following stress, SBF returned to pre-stress level in the healthy subjects, while a significant decrease of 33% was observed in the diabetics. The pre-stress heart rate level was higher and the stress-induced increase in heart rate was less in the diabetics compared with the healthy subjects (P<005). During the stress a slight–but insignificant–increase in blood-pressure was observed in both groups. In conclusion, we found that even mild mental strain influences SBF in both normal subjects and in diabetics. The induced alterations in the two groups are different, probably because of a slight parasympathetic dysfunction in the diabetics.     

Calcium utilization coupled to stimulation of postjunctional alpha-1 and alpha-2 adrenoceptors in isolated human resistance arteries.

Human s.c. resistance arteries (internal diameters 158-353 microns) were mounted in a microvascular myograph, and experiments were designed to examine the calcium pools utilized by selective stimulation of alpha-1 and alpha-2 adrenoceptors. In a concentration-dependent manner, phenylephrine and B-HT 933 evoked contractions mediated by alpha-1 and alpha-2 adrenoceptors, respectively, both in calcium-containing and in calcium-free saline. With respect to the maximum response to potassium in calcium-containing saline, the maximum responses to phenylephrine and B-HT 933 were 96 +/- 6 and 85 +/- 8%, respectively, in calcium-containing saline, and 79 +/- 4 and 14 +/- 2%, respectively, in calcium-free saline. A qualitatively similar difference in maximum responses to alpha-1 vs. alpha-2 adrenoceptor stimulation in calcium-free saline was demonstrated for norepinephrine in the presence of antagonists selective for the two alpha adrenoceptor subtypes. The maximum relaxation in calcium-containing saline produced by the calcium antagonist nitrendipine was 52 +/- 3% in vessels precontracted with phenylephrine, but 80 +/- 5% in vessels precontracted with B-HT 933. A quantitative difference in receptor reserves was demonstrated between alpha-1 and alpha-2 adrenoceptors; 90% of the maximum response was obtained at 34 +/- 5 and 57 +/- 8% receptor occupation, respectively. These data suggest that compared to responses mediated by stimulation of postjunctional alpha-1 adrenoceptors, stimulation of postjunctional alpha-2 adrenoceptors relies heavily on calcium influx. Stimulation of postjunctional alpha-2 adrenoceptors is, however, also coupled to intracellular release of calcium in isolated human s.c. resistance arteries.     

Plasma citrate during submaximal and intermittent supramaximal exercise

Plasma citrate was determined in seven subjects working 45 min at 50-60% of their maximal aerobic power and in six subjects who were exercised intermittently for five periods of 1 min at supramaximal work loads. Determinations of plasma lactate, glucose, free fatty acids and insulin were carried out simultaneously. During submaximal work the mean plasma citrate concentration decreased from 116 +/- 4 mumol/1 at rest to 108 +/- 5 mumol/1 after 10 min exercise (P less than 0.05) and increased above resting level to 136 +/- 5 mumol/1 40 min after cessation of work (P less than 0.05). During intermittent supramaximal exercise, mean plasma citrate concentration rose after the third work period and during recovery from 117 +/- 6 mumol/1 at rest to 181 +/- 9 mumol/1 40 min after last work period (P less than 0.05). Plasma citrate varied similarly to variations in plasma free fatty acids and inversely to changes of lactate concentrations during submaximal exercise. Opposite interrelationships were demonstrated during intermittent supramaximal exercise. Plasma citrate concentration varied in the same way as might be expected for changes in cytosolic citrate levels of muscle from in vitro knowledge of the regulatory role of citrate on glucose oxidation.     

Prediction of specific pathogens in patients with sepsis: evaluation of TREAT, a computerized decision support system

BACKGROUND: Prediction of bacterial infections and their pathogens allows for early, directed investigation and treatment. We assessed the ability of TREAT, a computerized decision support system, to predict specific pathogens. METHODS: TREAT uses data available within the first few hours of infection presentation in a causal probabilistic network to predict sites of infection and specific pathogens. We included 3529 patients (920 with microbiologically documented infections) participating in the observational and interventional trials of the TREAT system in Israel, Germany and Italy. Discriminatory performance of TREAT to predict individual pathogens was expressed by the AUC with 95% confidence intervals. Calibration was assessed using the Hosmer-Lemeshow goodness-of-fit statistic. RESULTS: The AUCs for Gram-negative bacteria, including Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella spp. and Escherichia coli, ranged between 0.70 and 0.80 (all significant). Adequate calibration was demonstrated for any Gram-negative infection and individual bacteria, except for E. coli. Discrimination and calibration were acceptable for Enterococcus spp. (AUC 0.71, 0.65-0.78), but not for Staphylococcus aureus (AUC 0.63, 0.55-0.71). The few infections caused by Candida spp. and Clostridium difficile were well predicted (AUCs 0.74, 0.54-0.95; and 0.94, 0.88-1.00, respectively). The coverage with TREAT's recommendation exceeded that observed with physicians' treatment for all pathogens, except Candida spp. CONCLUSIONS: TREAT predicted individual pathogens causing infection well. Prediction of S. aureus was inferior to that observed with other pathogens. TREAT can be used to triage patients by the risk for specific pathogens. The system's predictions enable it to prescribe appropriate antibiotic treatment prior to pathogen identification.     

SLP-65: A New Signaling Component in B Lymphocytes which Requires Expression of the Antigen Receptor for Phosphorylation

The B cell antigen receptor (BCR) consists of the membrane-bound immunoglobulin (Ig) molecule as antigen-binding subunit and the Ig-α/Ig-β heterodimer as signaling subunit. BCR signal transduction involves activation of protein tyrosine kinases (PTKs) and phosphorylation of several proteins, only some of which have been identified. The phosphorylation of these proteins can be induced by exposure of B cells either to antigen or to the tyrosine phosphatase inhibitor pervanadate/H₂O₂. One of the earliest substrates in B cells is a 65-kD protein, which we identify here as a B cell adaptor protein. This protein, named SLP-65, is part of a signaling complex involving Grb-2 and Vav and shows homology to SLP-76, a signaling element of the T cell receptor. In pervanadate/H₂O₂-stimulated cells, SLP-65 becomes phosphorylated only upon expression of the BCR. These data suggest that SLP-65 is part of a BCR transducer complex.     

Energy cost, exercise intensity, and gait efficiency of standard versus rocker-bottom axillary crutch walking

The purpose of this study was to investigate differences in selected biomechanical and physiological measurements and subjective preferences for ambulation with the standard single-tip axillary crutch versus the rocker-bottom-type axillary crutch. Self-selected walking velocities (S-SWVs) and stride length for each crutch type were determined for a two-point, non-weight-bearing, swing-through gait in 24 healthy volunteers. Relative exercise intensity, oxygen uptake (VO2), and gait efficiency were assessed for each crutch type at both S-SWVs. Subjects negotiated two architectural barriers (stairs and ramp) and completed a subjective questionnaire concerning crutch preferences. Walking with either crutch type resulted in slower S-SWVs, greater VO2, higher relative exercise intensity, and reduced gait efficiency compared with values for normal unassisted ambulation. An analysis of variance for these variables revealed nonsignificant between-crutch differences. Based on the subjective data, a preference for the standard single-tip crutch was evident. Within the scope of the study, the results supported no apparent advantage relative to energy expenditure to using the rocker-bottom crutch.     

Parathyroid hormone in serum during lithium therapy

In ten patients parathyroid hormone, urinary calcium excretion, and fractional tubular reabsorption of calcium were determined at intervals during three months of lithium treatment. Parathyroid hormone increased more than 40% within the first week and remained elevated throughout the treatment period. Calcium excretion fell by more than 30% within the first week and remained low throughout the treatment period. The reduction in urinary calcium excretion could be accounted for by an increase in fractional tubular reabsorption of calcium. There were no significant changes in serum calcium and inorganic phosphate or in urinary inorganic phosphate. The results indicate that lithium treatment affects the hormonal regulation of calcium metabolism.