Pig liver carnitine palmitoyltransferase. Chimera studies show that both the N- and C-terminal regions of the enzyme are important for the unusual high malonyl-CoA sensitivity.

Pig and rat liver carnitine palmitoyltransferase I (L-CPTI) share common K(m) values for palmitoyl-CoA and carnitine. However, they differ widely in their sensitivity to malonyl-CoA inhibition. Thus, pig l-CPTI has an IC(50) for malonyl-CoA of 141 nm, while that of rat L-CPTI is 2 microm. Using chimeras between rat L-CPTI and pig L-CPTI, we show that the entire C-terminal region behaves as a single domain, which dictates the overall malonyl-CoA sensitivity of this enzyme. The degree of malonyl-CoA sensitivity is determined by the structure adopted by this domain. Using deletion mutation analysis, we show that malonyl-CoA sensitivity also depends on the interaction of this single domain with the first 18 N-terminal amino acid residues. We conclude that pig and rat L-CPTI have different malonyl-CoA sensitivity, because the first 18 N-terminal amino acid residues interact differently with the C-terminal domain. This is the first study that describes how interactions between the C- and N-terminal regions can determine the malonyl-CoA sensitivity of L-CPTI enzymes using active C-terminal chimeras.     

Dehydroepiandrosterone feeding and protein phosphorylation, phosphatases, and lipogenic enzymes in mouse liver

Dehydroepiandrosterone (DHEA) treatment is effective in preventing or delaying the onset of various genetic and induced disorders of mice and rats. Associated with the beneficial therapeutic effects exerted by action of this steroid is the development of hepatomegaly. To determine whether the changes associated with hepatomegaly also involve alterations in activities of tissue enzymes, we evaluated the effects of DHEA (0.45% in food, w/w) on hepatic protein kinases, phosphatases, and lipogenic enzymes in mice of various strains. The rates of fatty acid and cholesterol syntheses also were evaluated. DHEA administration resulted in profound changes in the sodium dodecylsulfate-polyacrylamide gel electrophoresis patterns of endogenous radiophosphorylated proteins obtained by incubation of liver homogenates with (gamma-32P]ATP. These changes were dependent upon the medium used for homogenization. Thus, when homogenates of liver tissue of DHEA-treated mice were prepared in Tris buffer containing sucrose (0.25 M) there was a marked decrease in phosphorylation of the proteins of relative molecular weight approximately 116,000 (Mr approximately 116,000), approximately 82,000, approximately 80,000, approximately 58,000, approximately 56,000, approximately 48,000, approximately 34,000, and approximately 31,000 compared with controls. With liver homogenates of DHEA-treated mice prepared in Tris buffer alone, there was a marked increase in phosphorylation of the proteins of Mr approximately 70,000, approximately 49,000, approximately 34,000, approximately 31,000, and 28,000 compared with controls. Moreover, the specific activity of kinases for endogenous protein acceptors in liver of control mice was higher than that in liver of DHEA-treated animals. The specific activities of casein kinase, cAMP-dependent protein kinase, and cGMP-dependent protein kinase remained unchanged with DHEA treatment, but the specific activity of histone kinase was increased approximately 30%. Long-term administration of DHEA also was associated with increases in the specific activities of liver AMPase and GTPase (approximately two times), but not of other nucleotidases, alkaline phosphatase, acid phosphatase, glucose-6-phosphatase, or phosphotyrosine phosphatase. The activity of hepatic NADP-linked malic enzyme was increased significantly (two to three times) by DHEA treatment of female mice of three different strains, but was unchanged in male C57BL/6 mice. The specific activities of hepatic glucose-6-phosphate dehydrogenase, NADP-linked isocitrate dehydrogenase, and ATP-citrate lyase were not affected significantly by DHEA treatment of mice. The rate of hepatic lipogenesis, determined by incorporation of tritium from 3H2O into fatty acids, was decreased approximately 70% in DHEA-treated mice, while the rate of cholesterol synthesis was increased approximately 44% compared with controls.     

Climatic niche conservatism and the evolutionary dynamics in species range boundaries: global congruence across mammals and amphibians

Aim Comparative evidence for phylogenetic niche conservatism – the tendency for lineages to retain their ancestral niches over long time scales – has so far been mixed, depending on spatial and taxonomic scale. We quantify and compare conservatism in the climatic factors defining range boundaries in extant continental mammals and amphibians in order to identify those factors that are most evolutionarily conserved, and thus hypothesized to have played a major role in determining the geographic distributions of many species. We also test whether amphibians show stronger signals of climatic niche conservatism, as expected from their greater physiological sensitivity and lower dispersal abilities. Location Global; continental land masses excluding Antarctica. Methods We used nearly complete global distributional databases to estimate the climatic niche conservatism in extant continental mammals and amphibians. We characterized the climatic niche of each species by using a suite of variables and separately investigate conservatism in each variable using both taxonomic and phylogenetic approaches. Finally, we explored the spatial, taxonomic and phylogenetic patterns in recent climatic niche evolution. Results Amphibians and mammals showed congruent patterns of conservatism in cold tolerance, with assemblages of escapee species (i.e. those escaping most from the climatic constraints of their ancestors) aggregated in the North Temperate Zone. Main conclusions The relative strength of climatic niche conservatism varies across the variables tested, but is strongest for cold tolerance in both mammals and amphibians. Despite the apparent conservatism in this variable, there is also a strong signal of recent evolutionary shifts in cold tolerance in assemblages inhabiting the North Temperate Zone. Our results thus indicate that distribution patterns of both taxa are influenced by both niche conservatism and niche evolution.     

Predicting potential distribution of the jaguar (Panthera onca) in Mexico: identification of priority areas for conservation

Aim The jaguar, Panthera onca, is a species of global conservation concern. In Mexico, the northernmost part of its distribution range, its conservation status, is particularly critical, while its potential and actual distribution is poorly known. We propose an ensemble model (EM) of the potential distribution for the jaguar in Mexico and identify the priority areas for conservation. Location Mexico. Methods We generated our EM based on three presence‐only methods (Ecological Niche Factor Analysis, Mahalanobis distance, Maxent) and considering environmental, biological and anthropogenic factors. We used this model to evaluate the efficacy of the existing Mexican protected areas (PAs), to evaluate the adequacy of the jaguar conservation units (JCUs) and to propose new areas that should be considered for conservation and management of the species in Mexico. Results Our results outline that 16% of Mexico (c. 312,000 km²) can be considered as suitable for the presence of the jaguar. Furthermore, 13% of the suitable areas are included in existing PAs and 14% are included in JCUs ( Sanderson et al., 2002 ). Main conclusions Clearly much more should be carried out to establish a proactive conservation strategy. Based on our results, we propose here new jaguar conservation and management areas that are important for a nationwide conservation blueprint.     

A comparison of statistical methods for the detection of hepatocellular carcinoma based on serum biomarkers and clinical variables

Background

Currently, a surgical approach is the best curative treatment for those with hepatocellular carcinoma (HCC). However, this requires HCC detection and removal of the lesion at an early stage. Unfortunately, most cases of HCC are detected at an advanced stage because of the lack of accurate biomarkers that can be used in the surveillance of those at risk. It is believed that biomarkers that could detect HCC early will play an important role in the successful treatment of HCC.

Methods

In this study, we analyzed serum levels of alpha fetoprotein, Golgi protein, fucosylated alpha-1-anti-trypsin, and fucosylated kininogen from 113 patients with cirrhosis and 164 serum samples from patients with cirrhosis plus HCC. We utilized two different methods, namely, stepwise penalized logistic regression (stepPLR) and model-based classification and regression trees (mob), along with the inclusion of clinical and demographic factors such as age and gender, to determine if these improved algorithms could be used to increase the detection of cancer.

Results and discussion

The performance of multiple biomarkers was found to be better than that of individual biomarkers. Using several statistical methods, we were able to detect HCC in the background of cirrhosis with an area under the receiver operating characteristic curve of at least 0.95. stepPLR and mob demonstrated better predictive performance relative to logistic regression (LR), penalized LR and classification and regression trees (CART) used in our prior study based on three-fold cross-validation and leave one out cross-validation. In addition, mob provided unparalleled intuitive interpretation of results and potential cut-points for biomarker levels. The inclusion of age and gender improved the overall performance of both methods among all models considered, while the stratified male-only subset provided the best overall performance among all methods and models considered.

Conclusions

In addition to multiple biomarkers, the incorporation of age and gender into statistical models significantly improved their predictive performance in the detection of HCC.

     

C5a Regulates IL-12+DC Migration to Induce Pathogenic Th1 and Th17 Cells in Sepsis

Objective

It is well known that complement system C5a is excessively activated during the onset of sepsis. However, it is unclear whether C5a can regulate dentritic cells (DCs) to stimulate adaptive immune cells such as Th1 and Th17 in sepsis.

Methods

Sepsis was induced by cecal ligation and puncture (CLP). CLP-induced sepsis was treated with anti-C5a or IL-12. IL-12⁺DC, IFNγ⁺Th1, and IL-17⁺Th17 cells were analyzed by flow cytometry. IL-12 was measured by ELISA.

Results

Our studies here showed that C5a induced IL-12⁺DC cell migration from the peritoneal cavity to peripheral blood and lymph nodes. Furthermore, IL-12⁺DC cells induced the expansion of pathogenic IFNγ⁺Th1 and IL-17⁺Th17 cells in peripheral blood and lymph nodes. Moreover, IL-12, secreted by DC cells in the peritoneal cavity, is an important factor that prevents the development of sepsis.

Conclusion

Our data suggests that C5a regulates IL-12⁺DC cell migration to induce pathogenic Th1 and Th17 cells in sepsis.     

Hyperbaric Oxygen Promotes Proximal Bone Regeneration and Organized Collagen Composition during Digit Regeneration

Oxygen is critical for optimal bone regeneration. While axolotls and salamanders have retained the ability to regenerate whole limbs, mammalian regeneration is restricted to the distal tip of the digit (P3) in mice, primates, and humans. Our previous study revealed the oxygen microenvironment during regeneration is dynamic and temporally influential in building and degrading bone. Given that regeneration is dependent on a dynamic and changing oxygen environment, a better understanding of the effects of oxygen during wounding, scarring, and regeneration, and better ways to artificially generate both hypoxic and oxygen replete microenvironments are essential to promote regeneration beyond wounding or scarring. To explore the influence of increased oxygen on digit regeneration in vivo daily treatments of hyperbaric oxygen were administered to mice during all phases of the entire regenerative process. Micro-Computed Tomography (μCT) and histological analysis showed that the daily application of hyperbaric oxygen elicited the same enhanced bone degradation response as two individual pulses of oxygen applied during the blastema phase. We expand past these findings to show histologically that the continuous application of hyperbaric oxygen during digit regeneration results in delayed blastema formation at a much more proximal location after amputation, and the deposition of better organized collagen fibers during bone formation. The application of sustained hyperbaric oxygen also delays wound closure and enhances bone degradation after digit amputation. Thus, hyperbaric oxygen shows the potential for positive influential control on the various phases of an epimorphic regenerative response.