The effect of early versus delayed challenge after vaccination in controlling SHIV 89.6P infection

We sought to determine how effectively a CD8+ T cell inducing vaccine controls SHIV-89.6P infection in rhesus macaques at a range of challenge times post-vaccination. To this end, twenty eight Mamu-A*01+ rhesus macaques were given replication incompetent human serotype 5 adenovirus vector expressing SIVmac239 gag DNA and boosted 24 weeks later. Groups of 4 monkeys were then challenged with SHIV-89.6P at 1, 3, 6, 12, and 24 weeks after the boost. We compared the kinetics of viral load, CD4+ and virus-specific CD8+ T cells in these macaques. Measurements of CD8+ T cells taken before challenge show an exponential decay between 1 and 12 weeks following vaccination (p<0.0001). After week 12, no further decay was observed. Twenty of 24 vaccinated animals maintained more CD4+ T cells and kept their viral load at least one order of magnitude lower than the control animals throughout the chronic phase of the study. All 24 vaccinated animals survived the duration of the study. The viral and T cell kinetics over the first two weeks differed between the vaccinated groups, with more recent vaccination improving the early control of virus (p-value=0.027). The rates of virus specific CD8+ T cell expansion were greater in animals having higher viral loads at one week (r=0.45, p=0.029), suggesting that the kinetics of early viral load may have a role in virus specific CD8+ T cell generation, although these early differences did not lead to different clinical outcomes within the vaccinated animals.     

Impaired adaptability of in vivo mitochondrial energetics to acute oxidative insult in aged skeletal muscle

Periods of elevated reactive oxygen species (ROS) production are a normal part of mitochondrial physiology. However, little is known about age-related changes in the mitochondrial response to elevated ROS in vivo. Significantly, ROS-induced uncoupling of oxidative phosphorylation has received attention as a negative feedback mechanism to reduce mitochondrial superoxide production. Here we use a novel in vivo spectroscopy system to test the hypothesis that ROS-induced uncoupling is diminished in aged mitochondria. This system simultaneously acquires ³¹P magnetic resonance and near-infrared optical spectra to non-invasively measure phosphometabolite and O₂ concentrations in mouse skeletal muscle. Using low dose paraquat to elevate intracellular ROS we assess in vivo mitochondrial function in young, middle aged, and old mice. Oxidative phosphorylation was uncoupled to the same degree in response to ROS at each age, but this uncoupling was associated with loss of phosphorylation capacity and total ATP in old mice only. Using mice lacking UCP3 we demonstrate that this in vivo uncoupling is independent of this putative uncoupler of skeletal muscle mitochondria. These data indicate that ROS-induced uncoupling persists throughout life, but that oxidative stress leads to mitochondrial deficits and loss of ATP in aged organisms that may contribute to impaired function and degeneration.     

Hereditary breast/ovarian and colorectal cancer genetics knowledge in a national sample of US physicians

Background: Clinically relevant genetics knowledge is essential for appropriate assessment and management of inherited cancer risk, and for effective communication with patients. This national physician survey assessed knowledge regarding basic cancer genetics concepts early in the process of introduction of predictive genetic testing for breast/ovarian and hereditary non-polyposis colorectal cancer (HNPCC) syndromes. Methods: A stratified random sample was selected from the American Medical Association Masterfile of all licensed physicians. In total, 1251 physicians (820 in primary care, 431 in selected subspecialties) responded to a 15 minute questionnaire (response rate 71%) in 1999–2000. Multivariate logistic regression analyses were conducted to identify demographic and practice characteristics associated with accurate response to three knowledge questions. Results: Of the study population, 37.5% was aware of paternal inheritance of BRCA1/2 mutations, and 33.8% recognised that these mutations occur in <10% of breast cancer patients. Only 13.1% accurately identified HNPCC gene penetrance as ⩾50%. Obstetrics/gynaecology physicians, oncologists, and general surgeons were significantly more likely than general and family practitioners to respond accurately to the breast/ovarian questions, as were gastroenterologists to the HNPCC question. Conclusions: These nationally representative data indicate limited physician knowledge about key cancer genetics concepts in 1999–2000, particularly among general primary care physicians. Specialists were more knowledgeable about syndromes they might treat or refer elsewhere. Recent dissemination of practice guidelines and continued expansion of relevant clinical literature may enhance knowledge over time. In addition to educational efforts to assist physicians with the growing knowledge base, more research is needed to characterise the organisational changes required within the healthcare system to provide effective cancer genetics services.     

Thyroid hormone effects on mitochondrial energetics.

Thyroid hormones are the major endocrine regulators of metabolic rate, and their hypermetabolic effects are widely recognized. The cellular mechanisms underlying these metabolic effects have been the subject of much research. Thyroid hormone status has a profound impact on mitochondria, the organelles responsible for the majority of cellular adenosine triphosphate (ATP) production. However, mechanisms are not well understood. We review the effects of thyroid hormones on mitochondrial energetics and principally oxidative phosphorylation. Genomic and nongenomic mechanisms have been studied. Through the former, thyroid hormones stimulate mitochondriogenesis and thereby augment cellular oxidative capacity. Thyroid hormones induce substantial modifications in mitochondrial inner membrane protein and lipid compositions. Results are consistent with the idea that thyroid hormones activate the uncoupling of oxidative phosphorylation through various mechanisms involving inner membrane proteins and lipids. Increased uncoupling appears to be responsible for some of the hypermetabolic effects of thyroid hormones. ATP synthesis and turnover reactions are also affected. There appear to be complex relationships between mitochondrial proton leak mechanisms, reactive oxygen species production, and thyroid status. As the majority of studies have focused on the effects of thyroid status on rat liver preparations, there is still a need to address fundamental questions regarding thyroid hormone effects in other tissues and species.     

Discovery of a series of phosphonic acid-containing thiazoles and orally bioavailable diamide prodrugs that lower glucose in diabetic animals through inhibition of fructose-1,6-bisphosphatase

Oral delivery of previously disclosed purine and benzimidazole fructose-1,6-bisphosphatase (FBPase) inhibitors via prodrugs failed, which was likely due to their high molecular weight (>600). Therefore, a smaller scaffold was desired, and a series of phosphonic acid-containing thiazoles, which exhibited high potency against human liver FBPase (IC(50) of 10-30 nM) and high selectivity relative to other 5'-adenosinemonophosphate (AMP)-binding enzymes, were discovered using a structure-guided drug design approach. The initial lead compound (30j) produced profound glucose lowering in rodent models of type 2 diabetes mellitus (T2DM) after parenteral administration. Various phosphonate prodrugs were explored without success, until a novel phosphonic diamide prodrug approach was implemented, which delivered compound 30j with good oral bioavailability (OBAV) (22-47%). Extensive lead optimization of both the thiazole FBPase inhibitors and their prodrugs culminated in the discovery of compound 35n (MB06322) as the first oral FBPase inhibitor advancing to human clinical trials as a potential treatment for T2DM.     

Do Men Receive Information Required for Shared Decision Making About PSA Testing? Results from a National Survey

Most professional organizations, including the American College of Physicians and U.S. Preventive Services Task Force, emphasize that screening for prostate cancer with the prostate-specific antigen (PSA) test should only occur after a detailed discussion between the health-care provider and patient about the known risks and potential benefits of the test. In fact, guidelines strongly advise health-care providers to involve patients, particularly those at elevated risk of prostate cancer, in a “shared decision making” (SDM) process about PSA testing. We analyzed data from the National Cancer Institute’s Health Information National Trends Survey 2011–2012—a nationally representative, cross-sectional survey—to examine the extent to which health professionals provided men with information critical to SDM prior to PSA testing, including (1) that patients had a choice about whether or not to undergo PSA testing, (2) that not all doctors recommend PSA testing, and (3) that no one is sure if PSA testing saves lives. Over half (55 %) of men between the ages of 50 and 74 reported ever having had a PSA test. However, only 10 % of men, regardless of screening status, reported receiving all three pieces of information: 55 % reported being informed that they could choose whether or not to undergo testing, 22 % reported being informed that some doctors recommend PSA testing and others do not, and 14 % reported being informed that no one is sure if PSA testing actually saves lives. Black men and men with lower levels of education were less likely to be provided this information. There is a need to improve patient-provider communication about the uncertainties associated with the PSA test. Interventions directed at patients, providers, and practice settings should be considered.