Hasil untuk "Biology"

K. Carlander

G. Parker, J. M. Smith

P. Lieberman

W. Hawley

P. Dias

E. Cupp

M. G. Mullins, A. Bouquet, L. Williams

M. Burgman, S. Ferson, H. Akçakaya

G. Theißen, H. Saedler

F. Kuhajda

This review documents the changing perspectives on the function of fatty-acid synthase and fatty-acid synthesis in human tumor biology. With the recent discovery that human cancer cells express high levels of fatty-acid synthase and undergo significant endogenous fatty-acid synthesis, our understanding of the role of fatty acids in tumor biology is expanding. Once considered largely an anabolic-energy-storage pathway, fatty-acid synthesis is now associated with clinically aggressive tumor behavior and tumor-cell growth and survival and has become a novel target pathway for chemotherapy development. These findings will ultimately enhance our understanding of fatty acids in tumor biology and may provide new diagnostic and therapeutic moieties for patient care.

A. R. Wagner

W. Weckwerth

Ana Paula Yumi Nishimura, Fernando Augusto Pedersen Voll, Nadia Krieger et al.

Kinetic models are important tools for guiding the design and optimization of lipase-catalyzed processes. These processes follow the Ping Pong bi bi mechanism, for which mechanistic kinetic equations can be derived. However, when there are several competing reactions, fully mechanistic models contain a large number of parameters, making it difficult to obtain reliable estimates, so simplified models are necessary. We present a two-step approach to developing semi-mechanistic models of such processes. The first step involves the estimation of the selectivities of the enzyme, using profiles for the reaction species plotted against the degree of reaction, while the second step involves empirical fitting to the same data, but plotted as a function of time. We demonstrate this two-step approach through four case studies based on the literature data for the lipase-catalyzed esterification of fatty acids with trimethylolpropane to produce biolubricants. The semi-mechanistic models were able to describe the data well. Our approach has the advantage of allowing selectivities to be estimated without confounding effects from phenomena such as enzyme denaturation and inhibition. It therefore provides a promising framework for developing models of enzyme-catalyzed processes that obey Ping Pong bi bi kinetics.

S. Jansson, C. Douglas

G. Mayer

Ling Chen, Yujie Zhu, Xi Yang et al.

Abstract Obesity is a significant risk factor for thoracic aortic dissection (TAD), as supported by UK Biobank data showing obese individuals have a higher risk of TAD. The study investigates leptin, a hormone elevated in obesity, and finds that hyperleptinemia is common in TAD patients, suggesting its role in disease pathogenesis. Using leptin‐knockout mice, it is demonstrated that exogenous leptin exacerbates TAD by promoting phenotypic transitions in vascular smooth muscle cells (VSMCs). These adverse effects are reversible with pharmacologic leptin blockade, indicating potential therapeutic benefits. Single‐cell RNA sequencing reveals a novel smooth muscle cells (SMC) cluster, Nrip2+, in the aorta, with a distinct contractile gene profile. Increased Nrip2+ VSMCs are linked to enhanced mitochondrial energy metabolism. Elevated Nrip2+ VSMCs inhibit the leptin‐induced transition from a contractile to a synthetic phenotype, reducing TAD incidence. The findings suggest that high blood leptin levels contribute to the increased TAD risk in obese individuals by suppressing Nrip2+ SMCs, leading to abnormal mitochondrial metabolism and VSMC phenotypic transitions. Thus, targeting leptin to boost Nrip2+ VSMC metabolic activity is a promising strategy for TAD prevention and treatment.

Xi Chen, A. Varki

B. McStay, I. Grummt

J. Lalucat, A. Bennasar, R. Bosch et al.

Qide Jin, Yeping Wang, Kun Zhang et al.

Abstract Daphnia can avoid predation by sensing fish kairomones and producing inducible defenses by altering the phenotype. In this study, the results showed that the morphological and life‐history strategies of two Daphnia species (Daphnia pulex and Daphnia sinensis) exposed to Aristichthys nobilis kairomones. In the presence of fish kairomones, the two Daphnia species exhibited significantly smaller body length at maturity, smaller body length of offspring at the 10th instar, and longer relative tail spine of offspring. Nevertheless, other morphological and life‐history traits of the two Daphnia species differed. D. pulex showed a significantly longer relative tail spine length and earlier age at maturity after exposure to fish kairomones. The total offspring number of D. sinensis exposed to fish kairomones was significantly higher than that of the control group, whereas that of D. pulex was significantly lower. These results suggest that the two Daphnia species have different inducible defense strategies (e.g., morphological and life‐history traits) during prolonged exposure to A. nobilis kairomones, and their offspring also develop morphological defenses to avoid predation. It will provide reference for further exploring the adaptive evolution of Daphnia morphology and life‐history traits in the presence of planktivorous fish.