Extracellular acidic environments induce phosphorylation of ZAP-70 in Jurkat T cells

In solid tumor and inflammation loci, low pH conditions have been observed as a consequence of either a lack of sufficient vascularization or excess activity of tumor cells, and T cells have been reported to infiltrate tumors and inflammation sites. However, it remains unclear how extracellular acidic environments affect immune cell function. A previous report proposed that a different signal transduction cascade might occur under low pH conditions in Jurkat T cells (Fukamachi T, Saito H, Kakegawa T, Kobayashi H. Different proteins are phosphorylated under acidic environments in Jurkat cells. Immunol Lett 2002;82:155-8). In this study, we investigated the protein phosphotyrosine level in Jurkat and Jurkat mutant cells under different pH conditions. The ZAP-70 phosphorylation level increased under acidic environments. P38 MAPK was more activated at acidic pH. The level of active p38 was low in mutant P116 deficient in ZAP-70, and interestingly the level remained consistently low at all pH values tested. The activation of ERK was not stimulated at low pH. These results suggest that extracellular low pH stimulates or enhances TCR signaling via ZAP-70 and p38.     

Diurnal sedative changes during intensive care: Impact on liberation from mechanical ventilation and delirium*

OBJECTIVE:: To determine whether benzodiazepine and propofol doses are increased at night and whether daytime and nighttime sedative doses are associated with delirium, coma, and delayed liberation from mechanical ventilation. DESIGN:: Single-center, prospective cohort study nested within the Awakening and Breathing Controlled randomized trial. SETTING:: Saint Thomas Hospital in Nashville, TN, from 2004 to 2006. PATIENTS:: Adult patients receiving mechanical ventilation for >12 hrs with continuous recording of hourly sedation dosing. INTERVENTIONS:: We measured hourly doses of benzodiazepine and propofol exposure during the daytime (7 AM to 11 PM) and nighttime (11 PM to 7 AM) for 5 days. We quantified nighttime dose increases by subtracting the average hourly daytime dose on the preceding day from subsequent average hourly nighttime dose. We used multivariable logistic regression to determine whether daytime and nighttime dose increases were independently associated with delirium, coma, and delayed liberation from mechanical ventilation. MEASUREMENTS AND MAIN RESULTS:: Among 140 patients, the median Acute Physiology and Chronic Health Evaluation II score was 27 (interquartile range 22-33). Among those receiving the sedatives, benzodiazepine and propofol doses were increased at night on 40% and 41% of patient-days, respectively. Of 485 patient-days, delirium was present on 160 (33%) and coma on 206 (42%). In adjusted models, greater daytime benzodiazepine dose was independently associated with failed spontaneous breathing trial and extubation, and subsequent delirium (p < .02 for all). Nighttime increase in benzodiazepine dose was associated with failed spontaneous breathing trial (p < .01) and delirium (p = .05). Daytime propofol dose was marginally associated with subsequent delirium (p = .06). CONCLUSIONS:: Nearly half of mechanically ventilated intensive care unit patients received greater doses of sedation at night, a practice associated with failed spontaneous breathing trials, coma, and delirium. Over the first 5 days in our study, patients spent 75% of their time in coma or delirium, outcomes that may be reduced by efforts to decrease sedative exposure during both daytime and nighttime hours in the intensive care unit.     

Polarization Toward Th1-Type Response in Active, but Not in Inactive, Lupus Inhibits Late Allergic Rhinitis in Lupus-Prone Female NZB×NZWF1 Mice

The association of allergic diseases and disease activity in systemic lupus erythematosus (SLE, lupus) is controversial. The study investigates lupus activity-related differences in the induction of late allergic rhinitis (LAR) in the female NZB×NZW(B/W)F₁ mouse model for lupus. The LAR, which is induced by ovalbumin, was examined during the preactive (before clinical onset) and active (after clinical onset) phases in mice. Induction of LAR was less severe in mice with active lupus in contrast to clinically healthy lupus mice that developed a more severe allergic rhinitis. Inhibition of the development of LAR may be due to reduced eosinophilia and local interleukin-4 secretion during active autoimmune disease. In addition, systemic interferon-??, but not IL-4, production increased during the active phase, but not the preactive phase. This suggests that the predominating Th1 lineage commitment in mice with active lupus may be responsible for the inhibition of the allergic Th2 response. The present study may shed some light on the controversy of the prevalence of allergic diseases in SLE patients.     

Free fatty acids are associated with insulin resistance but not coronary artery atherosclerosis in rheumatoid arthritis

Background

Free fatty acids (FFAs) affect insulin signaling and are implicated in the pathogenesis of insulin resistance and atherosclerosis. Inflammatory cytokines such as interleukin-6 (IL-6) increase lipolysis and thus levels of FFAs. We hypothesized that increased IL-6 concentrations are associated with increased FFAs resulting in insulin resistance and atherosclerosis in rheumatoid arthritis (RA).

Methods

Clinical variables, serum FFAs and inflammatory cytokines, homeostasis model assessment for insulin resistance (HOMA-IR), and coronary artery calcium were measured in 166 patients with RA and 92 controls. We compared serum FFAs in RA and controls using Wilcoxon rank sum tests and further tested for multivariable association by adjusting for age, race, sex and BMI. Among patients with RA, we assessed the relationship between serum FFAs and inflammatory cytokines, HOMA-IR, and coronary artery calcium scores using Spearman correlation and multivariable regression analyses.

Results

Serum FFAs did not differ significantly in patients with RA and controls (0.56 mmol/L [0.38–0.75] and 0.56 mmol/L [0.45–0.70] respectively, p = 0.75). Presence of metabolic syndrome was associated with significantly increased serum FFAs in both RA and controls (p = 0.035 and p = 0.025). In multivariable regression analysis that adjusted for age, race, sex and BMI, serum FFAs were associated with HOMA-IR (p = 0.011), CRP (p = 0.01), triglycerides (p = 0.005) and Framingham risk score (p = 0.048) in RA, but not with IL-6 (p = 0.48) or coronary artery calcium score (p = 0.62).

Conclusions

Serum FFAs do not differ significantly in patients with RA and controls. FFAs may contribute to insulin resistance, but are not associated with IL-6 and coronary atherosclerosis in RA.     

Relationship between early lymphocyte recovery and prognosis after allogeneic hematopoietic stem cell transplantation for acute leukemia in remission

To assess the relationship between early lymphocyte recovery and outcomes after allogeneic hematopoietic stem cell transplantation (SCT) for acute leukemia in remission, 79 adult patients (AML: 48, ALL: 31) who received transplantation between January 2000 and November 2009 were retrospectively analyzed. The median lymphocyte count on day 30 after SCT (LC30) was 465/μl (range, 10～2640). On comparison of clinical outcomes between patients with low (LC30<400/μl) and high (LC30≥400/μl) counts, the 5-year overall survival (OS) was significantly better in high LC30 group than in low LC30 group (81.6 vs. 52.6%, p=0.014), but the cumulative relapse rate (RR) and non-relapse mortality (NRM) at 5 years did not differ between the two groups. On multivariate analysis, low LC 30 (HR, 2.44; 95% CI, 1.02～5.88; p=0.046) and grade II～IV acute graft-versus-host disease (HR, 2.41; 95% CI, 0.99～5.90, p=0.0053) were significantly associated with worse OS. However, LC30 was not a risk factor for RR or NRM. These findings suggest that LC30 may be one of the outcome predictors for patients receiving SCT.     

A portable dermatoscope for easy, rapid examination of periungual nailfold capillary changes in patients with systemic sclerosis

Microvascular lesions are a predominant feature in systemic sclerosis (SSc) and seem to play a central pathogenic role. The presence of nailfold capillary abnormalities is useful in diagnosing SSc. Capillaroscopy, however, usually requires special equipment and may be time consuming. Dermatoscope has been presented as a new diagnostic tool for quick and efficient examination of nailfold capillaries for circumstances when standard microscope equipment is not available. To assess the practical utility of dermatoscope for assessment of capillary morphology in patients with SSc, 83 Japanese patients with SSc (68 women, 15 men) and 68 healthy controls were examined in the study. Twenty-one patients (16 women, 5 men) had diffuse cutaneous SSc and 62 (52 women, 10 men) had limited cutaneous SSc. Enlarged capillaries and hemorrhages were evaluated in all 10 fingers with either naked eyes or DermLite^? DL100 dermatoscope. Enlarged capillaries and hemorrhages were significantly more frequently detected with dermatoscope than without it. These findings were observed most frequently in the fourth finger. The presence of two or more enlarged capillaries in one or more fingers showed 83.1% sensitivity and 100% specificity for SSc. Among patients with SSc with anti-topoisomerase I antibody, the disease duration correlated negatively with the dermatoscopic number of enlarged capillaries and hemorrhages. Dermatoscope allows the easy and rapid identification of capillary nailfold morphological changes in SSc and should be routinely used for diagnosing SSc.     

Evolution of a divinyl chlorophyll-based photosystem in Prochlorococcus

Acquisition of new photosynthetic pigments has been a crucial process for the evolution of photosynthesis and photosynthetic organisms. In this process, pigment-binding proteins must evolve to fit new pigments. Prochlorococcus is a unique photosynthetic organism that uses divinyl chlorophyll (DVChl) instead of monovinyl chlorophyll. However, cyanobacterial mutants that accumulate DVChl immediately die even under medium-light conditions, suggesting that chlorophyll (Chl)-binding proteins had to evolve to fit to DVChl concurrently with Prochlorococcus evolution. To elucidate the coevolutionary process of Chl and Chl-binding proteins during the establishment of DVChl-based photosystems, we first compared the amino acid sequences of Chl-binding proteins in Prochlorococcus with those in other photosynthetic organisms. Two amino acid residues of the D1 protein, V205 and G282, are conserved in monovinyl chlorophyll-based photosystems; however, in Prochlorococcus, they are substituted with M205 and C282, respectively. According to the solved photosystem II structure, these amino acids are not involved in Chl binding. To mimic Prochlorococcus, V205 was mutated to M205 in the D1 protein from Synechocystis sp. PCC6803 and Synechocystis dvr mutant was transformed with this construct. Although these transgenic cells could not grow under high-light conditions, they acquired light tolerance and grew under medium-light conditions, whereas untransformed dvr mutants could not survive. Substitution of G282 for C282 contributed additional light tolerance, suggesting that the amino acid substitutions in the D1 protein played an essential role in the development of DVChl-based photosystems. Here, we discuss the coevolution of a photosynthetic pigment and its binding protein.     

Liver-specific mitochondrial respiratory chain complex I deficiency in fatal influenza encephalopathy

We report on a 4-year-old boy who died from influenza encephalopathy. The clinical course and microscopic findings of the autopsied liver were compatible with Reye's syndrome. We examined the mitochondrial respiratory chain function by blue native polyacrylamide gel electrophoresis (BN-PAGE), western blotting, and respiratory chain enzyme activity assays. The activity of liver respiratory chain complex (CO) I was markedly decreased (7.2% of the respective control activity); whereas, the other respiratory chain complex activities were substantially normal (CO II, 57.9%; CO III, 122.3%; CO IV, 161.0%). The activities of CO I-IV in fibroblasts were normal (CO I, 82.0%; CO II, 83.1%; CO III, 72.9%; CO IV, 97.3%). The patient was diagnosed with liver-specific complex I deficiency. This inborn disorder may have contributed to the fatal outcome. We propose that relying only on fibroblast respiratory chain complex activities may lead to the misdiagnosis of liver-specific complex I deficiency.