Multi-Tracer Studies of Brain Oxygen and Glucose Metabolism Using a Time-of-Flight Positron Emission Tomography - Computed Tomography Scanner.

The authors have developed a paradigm using positron emission tomography (PET) with multiple radiopharmaceutical tracers that combines measurements of cerebral metabolic rate of glucose (CMRGlc), cerebral metabolic rate of oxygen (CMRO2), cerebral blood flow (CBF), and cerebral blood volume (CBV), culminating in estimates of brain aerobic glycolysis (AG). These in vivo estimates of oxidative and non-oxidative glucose metabolism are pertinent to the study of the human brain in health and disease. The latest positron emission tomography-computed tomography (PET-CT) scanners provide time-of-flight (TOF) imaging and critical improvements in spatial resolution and reduction of artifacts.

Comparison of the Ekblom-Bak Submaximal Test to a Maximal Test in a Cohort of Healthy Younger and Older Adults in the United States.

Cardiorespiratory fitness (CRF) is routinely investigated in diverse populations, including in older adults of varying physical activity levels. Commonly performed maximal exercise testing protocols might be contraindicated and/or inadequate for older individuals who have physical or cognitive impairment. Moreover, early termination of an attempted maximal exercise test could result in underestimation of CRF in this population.

The State of the Science of Preterm Birth: Assessing Contemporary Screening and Preventive Strategies.

Preterm birth remains a leading cause of morbidity and mortality during the perinatal and neonatal periods. Now affecting approximately 1 in 10 births in the United States, preterm birth often occurs spontaneously and without a clear etiology. Careful assessment of risk factors, however, identifies vulnerable women allowing targeted interventions such as progestogen therapy and cerclage.

Acetylation of the Entamoeba histone H4 N-terminal domain is influenced by short-chain fatty acids that enter trophozoites in a pH-dependent manner.

Treatment of higher eukaryotic cells with short-chain fatty acids (SCFA) such as butyrate causes decreased levels of histone deacetylase (HDAC) activity and hyperacetylation of histones, and thereby affects gene expression, cell growth and differentiation. Entamoeba parasites encounter high levels of SCFA in the host colon, and in vitro these compounds allow trophozoite stage parasites to multiply but prevent their differentiation into infectious cysts. The Entamoeba invadens IP-1 histone H4 protein has an unusual number of lysines in its N-terminus, and these become hyperacetylated in trophozoites exposed to the HDAC inhibitors trichostatin A (TSA) or HC-toxin, but not in trophozoites exposed to butyrate.

Entamoeba invadens: restriction of ploidy by colonic short chain fatty acids.

The DNA content of Entamoeba parasites appears to be regulated by an unusual mechanism. This conclusion, however, was based on experiments that examined parasites grown in media that did not contain short chain fatty acids (SCFAs) normally found in the colonic lumen. Since one of these SCFAs, butyrate, is known to affect DNA replication in eukaryotic cells, we examined the effect of SCFAs on Entamoeba trophozoite DNA content.

Colonic short-chain fatty acids inhibit encystation of Entamoeba invadens.

Entamoeba parasites multiply as trophozoites in the layer of mucus that overlies the colonic epithelium. In response to stimuli that are not understood, trophozoites stop multiplying and differentiate into cysts that are released to infect another host. In the colon, Entamoeba trophozoites are exposed to the large variety of biochemicals that are carried into or are produced within this organ.