Comparison of citrated and fresh whole blood for viscoelastic coagulation testing during elective neurosurgery.

BACKGROUND: Previous viscoelastic haemostatic tests studies have often indicated a hypercoagulative test signal with citrated blood, which could influence clinical decision makings. PURPOSE: The aim of this study was to compare fresh and citrated whole blood using two non-automated viscoelastic ROTEM and Sonoclot tests. Our hypothesis was that citrated blood would demonstrate a hypercoagulative response in this setting, not tested before. METHODS: Perioperative viscoelastic coagulation changes were evaluated with a ROTEM and Sonoclot in 38 patients undergoing elective brain tumor surgery. The citrated samples were recalcified with CaCl2. Wilcoxon nonparametric-paired tests and Bland-Altman plots were performed to compare the fresh and citrated blood analyses. RESULTS: The citrated blood showed a hypercoagulative response in ROTEM NATEM-clot formation time and α-angle, Sonoclot-clot rate and platelet function, as compared to fresh blood (p<0.0001). CONCLUSIONS: Fresh whole blood may theoretically reflect in vivo haemostasis more closely than citrated analyses, which indicated a hypercoagulative response as compared to the fresh whole blood analyses Bland-Altman plots also indicated that ROTEM reference ranges in patients undergoing brain surgery should be redefined. Future studies must establish the correlation between viscoelastic test results using fresh or citrate anticoagulated blood and clinical outcomes, such as bleeding, transfusion or reoperation for postoperative haematoma.

Comparison of point-of-care hemostatic assays, routine coagulation tests, and outcome scores in critically ill patients.

PURPOSE: The purposes of the study are to compare point-of-care (POC) hemostatic devices in critically ill patients with routine laboratory tests and intensive care unit (ICU) outcome scoring assessments and to describe the time course of these variables in relation to mortality rate. MATERIALS AND METHODS: Patients admitted to the ICU with a prognosis of more than 3 days of stay were included. The POC devices, Multiplate platelet aggregometry, rotational thromboelastometry, and ReoRox viscoelastic tests, were used. All variables were compared between survivors and nonsurvivors. Point-of-care results were compared to prothrombin time, activated partial thromboplastin time, platelet count, fibrinogen concentration, and Sequential Organ Failure Assessment score and Simplified Acute Physiology Score 3. RESULTS: Blood was sampled on days 0 to 1, 2 to 3, and 4 to 10 from 114 patients with mixed diagnoses during 237 sampling events. Nonsurvivors showed POC and laboratory signs of hypocoagulation and decreased fibrinolysis over time compared to survivors. ReoRox detected differences between survivors and nonsurvivors better than ROTEM and Multiplate. CONCLUSIONS: All POC and routine laboratory tests showed a hypocoagulative response in nonsurvivors compared to survivors. ReoRox was better than ROTEM and Multiplate at detecting differences between surviving and nonsurviving ICU patients. However, Simplified Acute Physiology Score 3 showed the best association to mortality outcome.

Development of peptide-selected CD8 T cells in fetal thymic organ culture occurs via the conventional pathway.

Fetal thymic organ culture of TCR transgenic (Tg) tissue has been used to study issues of timing and specificity in T cell development. Because most TCR Tgs express a rearranged alphabeta TCR on the cell surface at an earlier stage in development than normal mice, there is a possibility that the conclusions of studies using TCR Tg cultures may not apply to normal development. In particular, in our studies of peptide-induced development of CD8 T cells, it is possible that the peptide acts on the immature double-negative cell, driving development of CD8 T cells without passing through a double-positive stage. This issue was examined by asking whether MHC class I restriction was required and by analyzing CD8beta levels and endogenous TCR alpha chain rearrangements. We found that if nonstimulatory peptides were used in fetal thymic organ culture, CD8 T cells developed via the conventional pathway, transiting through a double-positive stage. However, we could not rule out that cells selected in the presence of stimulatory peptides (agonists) did not develop directly from double-negative precursors.

Initiation of esophageal secondary peristalsis by slow fluid infusion in the opossum: effect of hydrochloric acid.

We investigated the mechanisms of slow fluid infusion-induced secondary peristalsis and the effects of hydrochloric acid on this response. In 13 chronically esophagostomized opossum, acidic and neutral barium sulfate were infused into the distal esophagus at a rate of 1.1 ml/min, while recording the esophageal dimension by videofluoroscopy and esophageal intraluminal pressure concurrently. The effects of atropine, tetrodotoxin, capsaicin, and bilateral cervical vagotomy on the response to slow fluid infusion were examined. Acidic barium initiated secondary peristalsis more frequently and at shorter latency with less increase of preperistaltic intraesophageal pressure than neutral barium (P < 0.05). Atropine abolished secondary peristalsis initiated by neutral barium. For acidic barium, atropine decreased the incidence of secondary peristalsis, increased the latency for initiation of secondary peristalsis, and initiated secondary peristalsis more distally (P < 0.05). Tetrodotoxin or vagotomy and capsaicin abolished activation of secondary peristalsis. We concluded that secondary peristalsis can be stimulated in response to slow distension by minute amounts of fluid. This peristalsis is atropine and capsaicin sensitive and vagally mediated. The presence of acid significantly lowers the threshold for stimulation of secondary peristalsis induced by slow fluid distension. This effect seems to be atropine resistant.

Single-cell analysis of signal transduction in CD4 T cells stimulated by antigen in vivo.

Flow cytometry was used to study signaling events in individual CD4 T cells after antigen recognition in the body. Phosphorylation of c-jun and p38 mitogen-activated protein kinase was detected within minutes in all antigen-specific CD4 T cells in secondary lymphoid tissues after injection of peptide antigen into the bloodstream. The remarkable rapidity of this response correlated with the finding that most naive T cells are in constant contact with dendritic antigen-presenting cells. Contrary to predictions from in vitro experiments, antigen-induced c-jun and p38 mitogen-activated protein kinase phosphorylation did not depend on CD28 signals and was insensitive to inhibition by cyclosporin A. Our results highlight the efficiency of the in vivo immune response and underscore the need to verify which signaling pathways identified in vitro actually operate under physiological conditions.

CD28 signaling augments Elk-1-dependent transcription at the c-fos gene during antigen stimulation.

Untransformed CD4(+) Th1 cells stimulated with Ag and APC demonstrated a dependence on B7- and CD28-mediated costimulatory signals for the expression and function of AP-1 proteins. The induction of transactivation by the c-fos gene regulator Elk-1 mirrored this requirement for TCR and CD28 signal integration. c-Jun N-terminal kinase (JNK) (but not extracellular signal-regulated kinase or p38) protein kinase activity was similarly inhibited by neutralizing anti-B7 mAbs. Blockade of JNK protein kinase activity with SB 202190 prevented both Elk-1 transactivation and c-Fos induction. These results identify a unique role for B7 costimulatory molecules and CD28 in the activation of JNK during Ag stimulation in Th1 cells, and suggest that JNK regulates Elk-1 transactivation at the c-fos gene to promote the formation of AP-1 complexes important to IL-2 gene expression.

Augmentation of deglutitive upper esophageal sphincter opening in the elderly by exercise.

Earlier studies have shown that the cross-sectional area of the deglutitive upper esophageal sphincter (UES) opening in healthy asymptomatic elderly individuals is reduced compared with healthy young volunteers. The aim of this study was to determine the effect of a head-raising exercise on swallow-induced UES opening and hypopharyngeal intrabolus pressure in the elderly. We studied a total of 31 asymptomatic healthy elderly subjects by videofluoroscopy and manometry before and after real (19 subjects) and sham (12 subjects) exercises. A significant increase was found in the magnitude of the anterior excursion of the larynx, the maximum anteroposterior diameter, and the cross-sectional area of the UES opening after the real exercise (P < 0.05). These changes were associated with a significant decrease in the hypopharyngeal intrabolus pressure studied in 12 (real-exercise) and 6 (sham-exercise) subjects (P < 0.05). A similar effect was not found in the sham-exercise group. In normal elderly subjects, deglutitive UES opening is amenable to augmentation by exercise aimed at strengthening the UES opening muscles. This augmentation is accompanied by a significant decrease in hypopharyngeal intrabolus pressure, indicating a decrease in pharyngeal outflow resistance. This approach may be helpful in some patients with dysphagia due to disorders of deglutitive UES opening.