Acid/base triggered interconversion of μ-η2:η2-peroxido and bis(μ-oxido) dicopper intermediates capped by proton-responsive ligands

CuII2(μ-η2:η2-peroxido) and CuIII2(μ-oxido)2 cores represent key intermediates in copper/dioxygen chemistry, and they are mechanistically important for biological hydroxylation and oxidation reactions mediated by dinuclear (type III) copper metalloenzymes. While the exact nature of the active species in different enzymes is still under debate, shifting equilibria between Cu x /O2 species is increasingly recognized as a means of switching between distinct reactivity patterns of these intermediates. Herein we report comprehensive spectroscopic, crystallographic and computational analysis of a family of synthetic CuII2(μ-η2:η2-peroxido) and CuIII2(μ-oxido)2 dicopper complexes with a bis(oxazoline) (BOX) capping ligand. In particular, we demonstrate that a reversible peroxido/bis(μ-oxido) interconversion of the [Cu2O2] core can be triggered by peripheral (de)protonation events on the ligand backbone. As the copper ions in the enzymes are typically supported by histidine imidazoles that offer a backside N atom amenable to potential (de)protonation, it is well conceivable that the shifting of equilibria between the [Cu2O2] species in response to changes in local pH is biologically relevant.

Quantifying energy intake in Pacific bluefin tuna (Thunnus orientalis) using the heat increment of feeding

Using implanted archival tags, we examined the effects of meal caloric value, food type (sardine or squid) and ambient temperature on the magnitude and duration of the heat increment of feeding in three captive juvenile Pacific bluefin tuna. The objective of our study was to develop a model that can be used to estimate energy intake in wild fish of similar body mass. Both the magnitude and duration of the heat increment of feeding (measured by visceral warming) showed a strong positive correlation with the caloric value of the ingested meal. Controlling for meal caloric value, the extent of visceral warming was significantly greater at lower ambient temperature. The extent of visceral warming was also significantly higher for squid meals compared with sardine meals. By using a hierarchical Bayesian model to analyze our data and treating individuals as random effects, we demonstrate how increases in visceral temperature can be used to estimate the energy intake of wild Pacific bluefin tuna of similar body mass to the individuals used in our study.

Migratory movements, depth preferences, and thermal biology of Atlantic bluefin tuna

The deployment of electronic data storage tags that are surgically implanted or satellite-linked provides marine researchers with new ways to examine the movements, environmental preferences, and physiology of pelagic vertebrates. We report the results obtained from tagging of Atlantic bluefin tuna with implantable archival and pop-up satellite archival tags. The electronic tagging data provide insights into the seasonal movements and environmental preferences of this species. Bluefin tuna dive to depths of >1000 meters and maintain a warm body temperature. Western-tagged bluefin tuna make trans-Atlantic migrations and they frequent spawning grounds in the Gulf of Mexico and eastern Mediterranean. These data are critical for the future management and conservation of bluefin tuna in the Atlantic.

Early prediction of outcome in score-identified, postcardiac surgical patients at high risk for sepsis, using soluble tumor necrosis factor receptor-p55 concentrations

OBJECTIVE

To investigate the prognostic value of increased serum concentrations of soluble tumor necrosis factor (TNF) receptors in patients at high risk for sepsis.

DESIGN

Prospective study.

SETTING

Cardiac surgical intensive care unit in a University Hospital.

PATIENTS

Those 27 of 870 consecutive postcardiac surgical patients who met a previously validated high-risk criterion for imminent sepsis (Acute Physiology and Chronic Health Evaluation II [APACHE II] score of > or = 24 on the first postoperative day [day 1]). In this population, systemic inflammatory response syndrome was present in 96% of the patients and the in-hospital mortality rate was 30%. In addition, ten postcardiac surgical patients with an uncomplicated course (mortality rate 0%) were studied for comparison.

INTERVENTIONS

Blood sampling for measurements of serum concentrations of TNF and soluble TNF receptors 55 kilodalton (TNF receptor-p55) and 75 kilodalton (TNF receptor-p75) on days 1, 2, 3, and 5.

MEASUREMENTS AND MAIN RESULTS

Compared with the ten patients with an uncomplicated course (group A), the high-risk patients had significantly higher baseline (day 1) serum concentrations of soluble TNF receptor-p55 (9.2 vs. 4.2 ng/mL) and soluble TNF receptor-p75 (9.2 vs. 5.5 ng/mL). These high-risk patients could be further differentiated into two subgroups: one (B) with a prompt decrease in APACHE II score and a good prognosis (mortality rate 0%) and another (C) with a persisting high risk of sepsis and mortality rate (40%, p < .05). Although baseline APACHE II score was similar in both high-risk subgroups, soluble TNF receptor-p55 concentrations were significantly higher in subgroup C compared with subgroup B already at baseline (10.7 vs. 4.7 ng/mL). The receiver operating characteristic curve for subgroup classification by soluble TNF receptor-p55 was in a discriminating position with an area (0.773 +/- 0.096), confirming soluble TNF receptor-p55 as a predictor of mortality. TNF and soluble TNF receptor-p75 concentrations were less predictive at baseline.

CONCLUSIONS

This study suggest that increased soluble TNF receptor-p55 concentrations in the serum of postcardiac surgical patients allow earlier prognostication of subsequent hospital course than APACHE II scores alone. This study further suggests that the combination of physiologic scores and cytokine receptor measurements could improve the predictive power of early postoperative risk stratification.

Bedeutung erhöhter TNF-Rezeptorspiegel bei herzchirurgischen Risikopatienten

Wir untersuchten prospektiv den prognostischen Wert erhöhter Serumkon-zentrationen der löslichen Tumor-Nekrose-Faktor-Rezeptoren (sTNFR) bei imminenter Sepsis. Die Studienpopulation bestand aus jenen 27 von insgesamt 870 konsekutiven postkardiochirurgischen Patienten, welche ein zuvor validiertes Hochrisikokriterium für eine imminente Sepsis aufwiesen [APACHE-II-Score (APII) > 24 am 1. postoperativen Tag (Tag 1)]. In dieser Population lag ein systemisches Inflammations-Reaktions-Syndrom (SIRS) bei 96% der Patienten vor, die Krankenhausletalität betrug 30%. Zusätzlich wurden 10 postkardiochirurgische Patienten mit unkompliziertem Verlauf (Letalität: 0%) zum Vergleich untersucht. Verglichen mit den 10 Patienten mit unkompliziertem Verlauf (Gruppe A), wiesen die Hochri-sikopatienten signifikant höhere Ausgangswerte (Tag 1) für sTNFR-p55 (9,2 vs. 4,2ng/ml) und sTNFR-p75 (9,2 vs. 5,5 ng/ml) auf. Für den vorgefundenen Kreatinin-Wertebereich (Maximalwert: 2,48 mg/dl) fanden wir keine Korrelation zwischen Kreatinin und sTNFR-p55 (r=0,10) bzw. sTNFR-p75 (r=0,19). Die Hochrisikopatienten konnten in 2 Subgruppen differenziert werden: in die Subgruppe B mit einem prompten Abfall des APII und einer guten Prognose (Letalität: 0%) und Subgruppe C mit persistierend hohem Risiko und hoher Letalität (40%, p < 0,05). Trotz vergleichbarer APII-Ausgangswerte in beiden Hochrisikosubgruppen wa-ren die sTNFR-p55-Spiegel in der Subgruppe C im Vergleich zu B bereits am Tag 1 signifikant erhöht (10,7 vs. 4,7 ng/ml). Die ROC-Kurve für die Subgruppenklassifikation mittels sTNFR-p55 zeigte bereits am Tag 1 eine gute Trennschärfe mit einer Fläche von 0,773+0,096, was den Parameter als Prognoseprädikator bestätigte. Die sTNFR-p75-Ausgangskonzentratio-nen wiesen eine geringere prädiktive Wertigkeit auf. Zusammengefaβt weist unsere Studie darauf hin, daβ erhöhte sTNFR-p55-Serumspiegel bei postkardiochirurgischen Patienten frühzeitiger den Schweregrad von Krankheitsverlauf und Prognose anzeigen als APII-Scores allein. Dies spricht dafür, daβ durch die Kombination von physiolo-gischen Scores und Zytokinrezeptormessungen die prädiktive Wertigkeit einer frühzeitigen postoperativen Risikostratifizierung erhöht werden kann.

The prognostic value of hypocholesterolemia in hospitalized patients

Clinical observations show that severe illness often leads to hypocholesterolemia. To verify this finding and to define the relationship between serum cholesterol and a patient's prognosis, a study was conducted in two large hospital populations. Of 24,000 and 61,463 adult patients (populations I and II) an average of 3.8% and 3.6% died in hospital, respectively. The mean serum cholesterol levels of patients who died was significantly lower than that of those who survived (163.6 mg/dl versus 217.8 mg/dl; P < 0.0001). The average cholesterol of surviving patients was similar to that of 6,543 healthy controls. During hospitalization serum cholesterol levels of < or = 100 mg/dl were encountered in 1.2% and 3.6% of patients of populations I and II, respectively. The mortality of these hypocholesterolemic patients was about tenfold higher than average and showed a strong, inverse, linear relationship with serum cholesterol concentrations. Patients whose serum cholesterol level dropped to less than 45 mg/dl did not survive. These data show that in severely ill patients serum cholesterol may decline to very low concentrations, and the prognosis is reflected by the degree of hypocholesterolemia, which thus may serve as a clinically useful prognostic parameter.

Induction of glomerulosclerosis by dietary lipids. A functional and morphologic study in the rat

Clinical and experimental data indicate that glomerular function and morphology may be influenced by plasma lipids. In familial lecithin-cholesterol-acyltransferase (LCAT) deficiency and in Fabry's disease, lipids accumulate in glomeruli and are assumed to induce sclerosis. The present study was undertaken to examine if dietary lipids could exert effects on the glomeruli of normal, unilaterally nephrectomized rats, and of rats with two-kidney, one clip (2-K,1C) hypertension. In rats with two kidneys on a diet rich in fat and cholesterol, cholesterol concentrations in very low density lipoproteins increased. In these rats the number of glomeruli with sclerotic foci was significantly higher than in rats on a low fat, cholesterol free diet. After 6 months on the diet the percentage of glomeruli with sclerosis (SC) was 13.2 +/- 4.1 (N = 9) in rats with a cholesterol diet and 1.8 +/- 0.6 (N = 11) in control rats (p less than 0.05). The fat and cholesterol diet exacerbated glomerular lesions in the remnant kidney model of uninephrectomized rats. The sclerosis in rats with only one kidney was 38.2 +/- 9.5 (N = 6) on a cholesterol diet compared with 8.7 +/- 3.0 (N = 6) in control rats after 6 months (p less than 0.05). After 3 to 4 months on a fat rich diet cholesterylester was increased in isolated glomeruli. The composition of the dietary lipids influenced the development of glomerular lesions. A linseed oil diet that is rich in unsaturated fatty acids, especially linolenic acid, did not cause major plasma lipid abnormalities and was accompanied by a low sclerosis (1.2 +/- 0.3; N = 9) for rats with two kidneys. In rats with chronic 2-K, 1C hypertension the percentage of glomeruli with partially sclerosed tufts in the unclipped kidney was significantly higher on a fat and cholesterol diet (F) than on a control diet (N) (SC: diet F 31.0 +/- 4.0, N = 13; diet N 12.2 +/- 2.6, N = 12; P less than 0.05). In the clipped kidney, protected against the arterial hypertension, only an increased number of glomeruli with mesangial expansion was noted in rats with the cholesterol diet. Glomerular hemodynamic factors seem to play an important pathogenetic role in the induction of glomerular sclerosis by a lipid rich diet. The fact that dietary lipids can aggravate glomerular lesions in states of arterial hypertension and nephron loss may have implications for the progression of renal disease in humans.