The capacity of particles to increase allergic sensitization is predicted by particle number and surface area, not by particle mass.

Particle exposure has traditionally been monitored as mass concentration of PM10 (particles with an aerodynamic diameter less than 10 microm), more recently also as PM2.5. The mass concentration is strongly influenced by the large particles. Therefore, particle mass is a poor measure for characterizing the amount of the small, possibly more biologically potent particles. We used polystyrene particles (PSP) ranging in diameter from 0.0588 to 11.14 microm, carbon black (CB), and diesel exhaust particles (DEP), to study the adjuvant effect of particles on the immune response to the allergen ovalbumin (OVA) after sc injection into the footpad of BALB/cA mice. At a given mass dose, the small particles (0.0588 and 0.202 microm PSP, CB, and DEP) increased the allergen-specific IgE serum levels to a substantially higher degree than the larger particles (1.053, 4.64, and 11.14 microm PSP). Further, in the draining lymph node during the primary response, the fine particles (0.202 microm) with OVA increased cell numbers, expression of surface markers (CD19, MHC class II, CD86, and CD23) and ex vivo production of IL-4 and IL-10, whereas the largest (11.14 microm) particles did not. Linear regression analyses indicated that the IgE response was not predicted by particle mass (R2 = 0.06), but was predicted by the total particle surface area (R2 = 0.64), number of particles (R2 = 0.62), and particle diameter (R2 = 0.58). In conclusion, we found that fine particles exerted stronger adjuvant effects on allergic responses than larger particles at equal mass doses. Consequently, the dose described as total particle surface area or particle number predicts the adjuvant effect of particles better than the currently used particle mass.     

Personality, physical activity, and symptoms of anxiety and depression: the HUNT study

Purpose

To analyze the association between physical activity (PA), symptoms of depression and anxiety, and personality traits.

Methods

Cross-sectional study from a Norwegian population-based survey conducted in the period 2006–2008. The sample consisted of a total of 38,743 subjects aged ≥19 years, 56.1 % women and 43.9 % men. Demographic variables, PA, depression and anxiety (The Hospital Anxiety and Depression Scale), and personality (Eysenck Personality Questionnaire) were assessed by self-reporting measurements.

Results

Individuals who reported moderate and high PA had significantly lower scores on depression and anxiety compared with less physically active individuals (p < 0.05). Significantly lower risk of HADS-defined depression and anxiety was associated with frequency, duration, and intensity of activity among women (p < 0.05), and significantly lower risk of HADS-defined depression was associated with frequency, duration, and intensity of activity among men (p < 0.05). There was a significant linear trend between extroversion and levels of PA (p < 0.01) and between neuroticism and PA (p < 0.01).

Conclusions

Subjects reporting regular leisure-time PA were less likely to report symptoms of HADS-defined depression and anxiety. Personality may be an underlying factor in explaining this association.     

Pain tolerance after stroke: The Tromsø study

Background

Stroke lesions might alter pain processing and modulation by affecting the widely distributed network of brain regions involved. We aimed to compare pain tolerance in stroke survivors and stroke-free persons in the general population, with and without chronic pain.

Methods

We included all participants of the sixth and seventh wave of the population-based Tromsø Study who had been tested with the cold pressor test (hand in cold water bath, 3°C, maximum time 106 s in the sixth wave and 120 s in the seventh) and who had information on previous stroke status and covariates. Data on stroke status were obtained from the Tromsø Study Cardiovascular Disease Register and the Norwegian Stroke Register. Cox regression models were fitted using stroke prior to study attendance as the independent variable, cold pressor endurance time as time variable and hand withdrawal from cold water as event. Statistical adjustments were made for age, sex, diabetes, hypertension, hyperlipidaemia, body mass index and smoking.

Results

In total 21,837 participants were included, 311 of them with previous stroke. Stroke was associated with decreased cold pain tolerance time, with 28% increased hazard of hand withdrawal (hazard ratio [HR] 1.28, 95% CI 1.10–1.50). The effect was similar in participants with (HR 1.28, 95% CI 0.99–1.66) and without chronic pain (HR 1.29, 95% CI 1.04–1.59).

Conclusions

Stroke survivors, with and without chronic pain, had lower cold pressor pain tolerance, with possible clinical implications for pain in this group.

Significance

We found lower pain tolerance in participants with previous stroke compared to stroke-free participants of a large, population-based study. The association was present both in those with and without chronic pain. The results may warrant increased awareness by health professionals towards pain experienced by stroke patients in response to injuries, diseases and procedures.     

Indirect CD4+ T‐cell‐mediated elimination of MHC IINEG tumor cells is spatially restricted and fails to prevent escape of antigen‐negative cells

Tumor‐specific Th1 cells can activate tumor‐infiltrating macrophages that eliminate MHC class II negative (MHC II^NEG) tumor cells. Activated M1‐like macrophages lack antigen (Ag) receptors, and are presumably unable to discriminate and thus kill both Ag‐positive (Ag^POS) and Ag‐negative (Ag^NEG) tumor cells (bystander killing). The lack of specificity of macrophage‐mediated cytotoxicity might be of clinical importance as it could provide a means of avoiding tumor escape. Here, we have tested this idea using mixed populations of Ag^POS and Ag^NEG tumor cells in a TCR‐transgenic model in which CD4⁺ T cells recognize a secreted tumor‐specific antigen. Surprisingly, while Ag^POS tumor cells were recognized and rejected, Ag^NEG cells grew unimpeded and formed tumors. We further demonstrated that macrophage‐mediated cytotoxicity was spatially restricted to areas dominated by Ag^POS tumor cells, sparing Ag^NEG tumor cells in the vicinity. As a consequence, macrophage tumoricidal activity did not confer bystander killing in vivo. The present results offer novel insight into the mechanisms of indirect Th1‐mediated elimination of MHC II^NEG tumor cells.     

Detecting postoperative urinary retention with an ultrasound scanner

BACKGROUND: Retention of urine is a common postoperative problem associated with risk of overdistention and permanent detrusor damage. Prevention of urinary retention by insertion of indwelling catheter may increase the risk of urinary infection. We have performed a reliability test of an ultrasound scanner, implemented in the postoperative monitoring equipment. METHODS: Patients were monitored after different types of surgery under spinal anesthesia with an ultrasound scanner in the postanesthesia care unit (PACU). PATIENTS: Patients who according to current guidelines required a urinary bladder catheter, were scanned before a catheter was inserted and urine volume was measured. These two urine volumes were compared and analyzed for agreement. RESULTS: Nineteen female and 17 male patients were included. The mean difference between ultrasound estimates and catheter urine volume measurements was - 21.5 mL, and limits of agreement, calculated as a 95% confidence interval, were - 147 and + 104 mL. This means that the urine volume estimated by ultrasound was on average 21.5 mL smaller than the urine volume when the bladder was emptied. CONCLUSION: This study confirms a good agreement between the ultrasound scanner estimates of urinary bladder volume and urine volume measured after emptying the bladder. Nurses in the PACU could operate the ultrasound scanner after a brief instruction and training period. Considering the potentially serious long-term consequences of undiagnosed postoperative urinary retention, introducing this equipment for routine monitoring of urinary bladder volume should be considered.     

Cardiac arrest after intravenous metoclopramide - a case of five repeated injections of metoclopramide causing five episodes of cardiac arrest

We describe a patient where intravenous injection of metoclopramide was immediately followed by asystole repeatedly. The patient received metoclopramide 10 mg i.v. five times during 48 h. After interviewing the attending nurses and reviewing the written documentation, it is clear that every administration of metoclopramide was immediately (within s) followed by asystole. The asystole lasted 15-30 s on four occasions, on one occasion it lasted 2 min. The patient received atropine 0.5-1 mg and chest compressions, before sinus rhythm again took over. We interpret this as episodes of cardiac arrest caused by metoclopramide. The rapid injection via the central venous route and the concomitant tapering of dopamine infusion might have contributed in precipitating the adverse drug reaction.     

Methylprednisolone intravenously 1 day after surgery has sustained analgesic and opioid-sparing effects

BACKGROUND: In previous studies on glucocorticoids for postoperative pain, the test drug has been given perioperatively, usually before measurement of baseline pain. In order to evaluate the time course and magnitude of the analgesic effect of a glucocorticoid in well-established postoperative pain, we compared methylprednisolone with ketorolac and placebo, after assessment of baseline pain on the first postoperative day. METHODS: This was a double-blind, single dose, randomized, parallel comparison of intravenous (i.v.) methylprednisolone 125 mg, ketorolac 30 mg as an active control, and placebo in 75 patients with moderate to severe pain 1 day after orthopaedic surgery. Outcome variables were pain intensity (0-100 VAS), pain relief (0-4 PAR) and rescue opioid consumption. RESULTS: Methylprednisolone was not significantly different from ketorolac and gave significantly lower pain intensity from 1 h (0-6 h, P < 0.02), and more pain relief 2-6 h after test drugs (P < 0.05) compared with placebo. After 24 h, pain intensity was lower in both active drug groups compared with placebo (methylprednisolone, P < 0.0001; ketorolac, P < 0.007). Number needed to treat (NNT) calculated from patients having more than at least 50% of maximum obtainable total pain relief during the first 6 h (>50%maxTOTPAR(6 h)) was 3.6 for methylprednisolone and 3.1 for ketorolac. Number needed to treat calculated from the percentage reporting at least 50% pain relief for at least 4 h (>50%PAR(4 h)) was 2.8 for both groups. Opioid consumption was significantly reduced for 72 h after methylprednisolone compared with ketorolac (P < 0.02) and placebo (P < 0.003). CONCLUSION: Methylprednisolone 125 mg i.v. 1 day after surgery gave similar early reduction of pain as i.v. ketorolac 30 mg. Less pain than placebo 24 h after methylprednisolone, and lower opioid consumption for 72 h compared with ketorolac and placebo indicate sustained analgesic effects of methylprednisolone.