Protein restriction slows the development and progression of Alzheimer's disease in mice

Dietary protein is a critical regulator of metabolic health and aging. Low protein diets are associated with healthy aging in humans, and many independent groups of researchers have shown that dietary protein restriction (PR) extends the lifespan and healthspan of mice. Here, we examined the effect of PR on metabolic health and the development and progression of Alzheimer's disease (AD) in the 3xTg mouse model of AD. We found that PR has metabolic benefits for 3xTg mice and non-transgenic controls of both sexes, promoting leanness and glycemic control in 3xTg mice and rescuing the glucose intolerance of 3xTg females. We found that PR induces sex-specific alterations in circulating metabolites and in the brain metabolome and lipidome, downregulating sphingolipid subclasses including ceramides, glucosylceramides, and sphingomyelins in 3xTg females. Consumption of a PR diet starting at 6 months of age reduced AD pathology in conjunction with reduced mTORC1 activity, increased autophagy, and had cognitive benefits for 3xTg mice. Finally, PR improved the survival of 3xTg mice. Our results demonstrate that PR slows the progression of AD at molecular and pathological levels, preserves cognition in this mouse model of AD, and suggests that PR or pharmaceutical interventions that mimic the effects of this diet may hold promise as a treatment for AD.

Late-life isoleucine restriction promotes physiological and molecular signatures of healthy aging

In defiance of the paradigm that calories from all sources are equivalent, we and others have shown that dietary protein is a dominant regulator of healthy aging. The restriction of protein or the branched-chain amino acid isoleucine promotes healthspan and extends lifespan when initiated in young or adult mice. However, many interventions are less efficacious or even deleterious when initiated in aged animals. Here, we investigate the physiological, metabolic, and molecular consequences of consuming a diet with a 67% reduction of all amino acids (Low AA), or of isoleucine alone (Low Ile), in male and female C57BL/6J.Nia mice starting at 20 months of age. We find that both diet regimens effectively reduce adiposity and improve glucose tolerance, which were benefits that were not mediated by reduced calorie intake. Both diets improve specific aspects of frailty, slow multiple molecular indicators of aging rate, and rejuvenate the aging heart and liver at the molecular level. These results demonstrate that Low AA and Low Ile diets can drive youthful physiological and molecular signatures, and support the possibility that these dietary interventions could help to promote healthy aging in older adults.

Dietary restriction of individual amino acids stimulates unique molecular responses in mouse liver

Dietary protein and essential amino acid (EAA) restriction promotes favorable metabolic reprogramming, ultimately resulting in improvements to both health and lifespan. However, as individual EAAs have distinct catabolites and engage diverse downstream signaling pathways, it remains unclear to what extent shared or AA-specific molecular mechanisms promote diet-associated phenotypes. Here, we investigated the physiological and molecular effects of restricting either dietary methionine, leucine, or isoleucine (Met-R, Leu-R, and Ile-R) for 3 weeks in C57BL/6J male mice. While all 3 AA-depleted diets promoted fat and lean mass loss and slightly improved glucose tolerance, the molecular responses were more diverse; while hepatic metabolites altered by Met-R and Leu-R were highly similar, Ile-R led to dramatic changes in metabolites, including a 3-fold reduction in the oncometabolite 2-hydroxyglutarate. Pathways regulated in an EAA-specific manner included glycolysis, the pentose phosphate pathway (PPP), nucleotide metabolism, the TCA cycle and amino acid metabolism. Transcriptiome analysis and global profiling of histone post-translational modifications (PTMs) revealed different patterns of responses to each diet, although Met-R and Leu-R again shared similar transcriptional responses. While the pattern of global histone PTMs were largely unique for each dietary intervention, Met-R and Ile-R had similar changes in histone-3 methylation/acetylation PTMs at lysine-9. Few similarities were observed between the physiological or molecular responses to EAA restriction and treatment with rapamycin, an inhibitor of the mTORC1 AA-responsive protein kinase, indicating the response to EAA restriction may be largely independent of mTORC1. Together, these results demonstrate that dietary restriction of individual EAAs has unique, EAA-specific effects on the hepatic metabolome, epigenome, and transcriptome, and suggests that the specific EAAs present in dietary protein may play a key role at regulating health at the molecular level.

Dietary restriction of isoleucine increases healthspan and lifespan of genetically heterogeneous mice

Low-protein diets promote health and longevity in diverse species. Restriction of the branched-chain amino acids (BCAAs) leucine, isoleucine, and valine recapitulates many of these benefits in young C57BL/6J mice. Restriction of dietary isoleucine (IleR) is sufficient to promote metabolic health and is required for many benefits of a low-protein diet in C57BL/6J males. Here, we test the hypothesis that IleR will promote healthy aging in genetically heterogeneous adult UM-HET3 mice. We find that IleR improves metabolic health in young and old HET3 mice, promoting leanness and glycemic control in both sexes, and reprograms hepatic metabolism in a sex-specific manner. IleR reduces frailty and extends the lifespan of male and female mice, but to a greater degree in males. Our results demonstrate that IleR increases healthspan and longevity in genetically diverse mice and suggests that IleR, or pharmaceuticals that mimic this effect, may have potential as a geroprotective intervention.

The Effects of Graded Levels of Calorie Restriction: XX. Impact of Long-Term Graded Calorie Restriction on Survival and Body Mass Dynamics in Male C57BL/6J Mice

Calorie restriction (CR) typically promotes a reduction in body mass, which correlates with increased lifespan. We evaluated the overall changes in survival, body mass dynamics, and body composition following long-term graded CR (580 days/19 months) in male C57BL/6J mice. Control mice (0% restriction) were fed ad libitum in the dark phase only (12-hour ad libitum [12AL]). CR groups were restricted by 10%-40% of their baseline food intake (10CR, 20CR, 30CR, and 40CR). Body mass was recorded daily, and body composition was measured at 8 time points. At 728 days/24 months, all surviving mice were culled. A gradation in survival rate over the CR groups was found. The pattern of body mass loss differed over the graded CR groups. Whereas the lower CR groups rapidly resumed an energy balance with no significant loss of fat or fat-free mass, changes in the 30 and 40CR groups were attributed to higher fat-free mass loss and protection of fat mass. Day-to-day changes in body mass were less variable under CR than for the 12AL group. There was no indication that body mass was influenced by external factors. Partial autocorrelation analysis examined the relationship between daily changes in body masses. A negative correlation between mass on Day 0 and Day +1 declined with age in the 12AL but not the CR groups. A reduction in the correlation with age suggested body mass homeostasis is a marker of aging that declines at the end of life and is protected by CR.

SIRT3 deficiency decreases oxidative metabolism capacity but increases lifespan in male mice under caloric restriction

Mitochondrial NAD⁺ -dependent protein deacetylase Sirtuin3 (SIRT3) has been proposed to mediate calorie restriction (CR)-dependent metabolic regulation and lifespan extension. Here, we investigated the role of SIRT3 in CR-mediated longevity, mitochondrial function, and aerobic fitness. We report that SIRT3 is required for whole-body aerobic capacity but is dispensable for CR-dependent lifespan extension. Under CR, loss of SIRT3 (Sirt3^-/- ) yielded a longer overall and maximum lifespan as compared to Sirt3^+/+ mice. This unexpected lifespan extension was associated with altered mitochondrial protein acetylation in oxidative metabolic pathways, reduced mitochondrial respiration, and reduced aerobic exercise capacity. Also, Sirt3^-/- CR mice exhibit lower spontaneous activity and a trend favoring fatty acid oxidation during the postprandial period. This study shows the uncoupling of lifespan and healthspan parameters (aerobic fitness and spontaneous activity) and provides new insights into SIRT3 function in CR adaptation, fuel utilization, and aging.

Regulation of metabolic health by dietary histidine in mice

Low-protein (LP) diets are associated with a decreased risk of diabetes in humans, and promote leanness and glycaemic control in both rodents and humans. While the effects of an LP diet on glycaemic control are mediated by reduced levels of the branched-chain amino acids, we have observed that reducing dietary levels of the other six essential amino acids leads to changes in body composition. Here, we find that dietary histidine plays a key role in the response to an LP diet in male C57BL/6J mice. Specifically reducing dietary levels of histidine by 67% reduces the weight gain of young, lean male mice, reducing both adipose and lean mass without altering glucose metabolism, and rapidly reverses diet-induced obesity and hepatic steatosis in diet-induced obese male mice, increasing insulin sensitivity. This normalization of metabolic health was associated not with caloric restriction or increased activity, but with increased energy expenditure. Surprisingly, the effects of histidine restriction do not require the energy balance hormone Fgf21. Histidine restriction that was started in midlife promoted leanness and glucose tolerance in aged males but not females, but did not affect frailty or lifespan in either sex. Finally, we demonstrate that variation in dietary histidine levels helps to explain body mass index differences in humans. Overall, our findings demonstrate that dietary histidine is a key regulator of weight and body composition in male mice and in humans, and suggest that reducing dietary histidine may be a translatable option for the treatment of obesity. KEY POINTS: Protein restriction (PR) promotes metabolic health in rodents and humans and extends rodent lifespan. Restriction of specific individual essential amino acids can recapitulate the benefits of PR. Reduced histidine promotes leanness and increased energy expenditure in male mice. Reduced histidine does not extend the lifespan of mice when begun in midlife. Dietary levels of histidine are positively associated with body mass index in humans.

Effects of dietary macronutrients on the hepatic transcriptome and serum metabolome in mice

Dietary macronutrient composition influences both hepatic function and aging. Previous work suggested that longevity and hepatic gene expression levels were highly responsive to dietary protein, but almost unaffected by other macronutrients. In contrast, we found expression of 4005, 4232, and 4292 genes in the livers of mice were significantly associated with changes in dietary protein (5%–30%), fat (20%–60%), and carbohydrate (10%–75%), respectively. More genes in aging‐related pathways (notably mTOR, IGF‐1, and NF‐kappaB) had significant correlations with dietary fat intake than protein and carbohydrate intake, and the pattern of gene expression changes in relation to dietary fat intake was in the opposite direction to the effect of graded levels of caloric restriction consistent with dietary fat having a negative impact on aging. We found 732, 808, and 995 serum metabolites were significantly correlated with dietary protein (5%–30%), fat (8.3%–80%), and carbohydrate (10%–80%) contents, respectively. Metabolomics pathway analysis revealed sphingosine‐1‐phosphate signaling was the significantly affected pathway by dietary fat content which has also been identified as significant changed metabolic pathway in the previous caloric restriction study. Our results suggest dietary fat has major impact on aging‐related gene and metabolic pathways compared with other macronutrients.

Sex and genetic background define the metabolic, physiologic, and molecular response to protein restriction

Low-protein diets promote metabolic health in humans and rodents. Despite evidence that sex and genetic background are key factors in the response to diet, most protein intake studies examine only a single strain and sex of mice. Using multiple strains and both sexes of mice, we find that improvements in metabolic health in response to reduced dietary protein strongly depend on sex and strain. While some phenotypes were conserved across strains and sexes, including increased glucose tolerance and energy expenditure, we observed high variability in adiposity, insulin sensitivity, and circulating hormones. Using a multi-omics approach, we identified mega-clusters of differentially expressed hepatic genes, metabolites, and lipids associated with each phenotype, providing molecular insight into the differential response to protein restriction. Our results highlight the importance of sex and genetic background in the response to dietary protein level, and the potential importance of a personalized medicine approach to dietary interventions.

FGF21 has a sex-specific role in calorie-restriction-induced beiging of white adipose tissue in mice

Calorie restriction (CR) promotes healthspan and extends the lifespan of diverse organisms, including mice, and there is intense interest in understanding the molecular mechanisms by which CR functions. Some studies have demonstrated that CR induces fibroblast growth factor 21 (FGF21), a hormone that regulates energy balance and that when overexpressed, promotes metabolic health and longevity in mice, but the role of FGF21 in the response to CR has not been fully investigated. We directly examined the role of FGF21 in the physiological and metabolic response to a CR diet by feeding Fgf21^-/- and wild-type control mice either ad libitum (AL) diet or a 30% CR diet for 15 weeks. Here, we find that FGF21 is largely dispensable for CR-induced improvements in body composition and energy balance, but that lack of Fgf21 blunts CR-induced changes aspects of glucose regulation and insulin sensitivity in females. Surprisingly, despite not affecting CR-induced changes in energy expenditure, loss of Fgf21 significantly blunts CR-induced beiging of white adipose tissue in male but not female mice. Our results shed new light on the molecular mechanisms involved in the beneficial effects of a CR diet, clarify that FGF21 is largely dispensable for the metabolic effects of a CR diet, and highlight a sex-dependent role for FGF21 in the molecular adaptation of white adipose tissue to CR.

A food with medicine approach to health

There is significant interest in identifying compounds that mimic the effects of dietary restriction on healthy aging. In the latest issue of Cell Metabolism, Le Couteur et al. (2021) use a nutritional geometry approach to survey the effects of three such compounds on the hepatic proteome across a changing dietary landscape.

Fasting drives the metabolic, molecular and geroprotective effects of a calorie-restricted diet in mice

Calorie restriction (CR) promotes healthy ageing in diverse species. Recently, it has been shown that fasting for a portion of each day has metabolic benefits and promotes lifespan. These findings complicate the interpretation of rodent CR studies, in which animals typically eat only once per day and rapidly consume their food, which collaterally imposes fasting. Here we show that a prolonged fast is necessary for key metabolic, molecular and geroprotective effects of a CR diet. Using a series of feeding regimens, we dissect the effects of calories and fasting, and proceed to demonstrate that fasting alone recapitulates many of the physiological and molecular effects of CR. Our results shed new light on how both when and how much we eat regulate metabolic health and longevity, and demonstrate that daily prolonged fasting, and not solely reduced caloric intake, is likely responsible for the metabolic and geroprotective benefits of a CR diet.

The Effects of Graded Levels of Calorie Restriction: XVI. Metabolomic Changes in the Cerebellum Indicate Activation of Hypothalamocerebellar Connections Driven by Hunger Responses

Calorie restriction (CR) remains the most robust intervention to extend life span and improve healthspan. Though the cerebellum is more commonly associated with motor control, it has strong links with the hypothalamus and is thought to be associated with nutritional regulation and adiposity. Using a global mass spectrometry-based metabolomics approach, we identified 756 metabolites that were significantly differentially expressed in the cerebellar region of the brain of C57BL/6J mice, fed graded levels of CR (10, 20, 30, and 40 CR) compared to mice fed ad libitum for 12 hours a day. Pathway enrichment indicated changes in the pathways of adenosine and guanine (which are precursors of DNA production), aromatic amino acids (tyrosine, phenylalanine, and tryptophan) and the sulfur-containing amino acid methionine. We also saw increases in the tricarboxylic acid cycle (TCA) cycle, electron donor, and dopamine and histamine pathways. In particular, changes in l-histidine and homocarnosine correlated positively with the level of CR and food anticipatory activity and negatively with insulin and body temperature. Several metabolic and pathway changes acted against changes seen in age-associated neurodegenerative disorders, including increases in the TCA cycle and reduced l-proline. Carnitine metabolites contributed to discrimination between CR groups, which corroborates previous work in the liver and plasma. These results indicate the conservation of certain aspects of metabolism across tissues with CR. Moreover, this is the first study to indicate CR alters the cerebellar metabolome, and does so in a graded fashion, after only a short period of restriction.

The effects of graded calorie restriction XVII: Multitissue metabolomics reveals synthesis of carnitine and NAD, and tRNA charging as key pathways

The evolutionary context of why caloric restriction (CR) activates physiological mechanisms that slow the process of aging remains unclear. The main goal of this analysis was to identify, using metabolomics, the common pathways that are modulated across multiple tissues (brown adipose tissue, liver, plasma, and brain) to evaluate two alternative evolutionary models: the "disposable soma" and "clean cupboards" ideas. Across the four tissues, we identified more than 10,000 different metabolic features. CR altered the metabolome in a graded fashion. More restriction led to more changes. Most changes, however, were tissue specific, and in some cases, metabolites changed in opposite directions in different tissues. Only 38 common metabolic features responded to restriction in the same way across all four tissues. Fifty percent of the common altered metabolites were carboxylic acids and derivatives, as well as lipids and lipid-like molecules. The top five modulated canonical pathways were l-carnitine biosynthesis, NAD (nicotinamide adenine dinucleotide) biosynthesis from 2-amino-3-carboxymuconate semialdehyde, S-methyl-5'-thioadenosine degradation II, NAD biosynthesis II (from tryptophan), and transfer RNA (tRNA) charging. Although some pathways were modulated in common across tissues, none of these reflected somatic protection, and each tissue invoked its own idiosyncratic modulation of pathways to cope with the reduction in incoming energy. Consequently, this study provides greater support for the clean cupboards hypothesis than the disposable soma interpretation.

The Second Annual Symposium of the Midwest Aging Consortium: The Future of Aging Research in the Midwestern United States

While the average human life span continues to increase, there is little evidence that this is leading to a contemporaneous increase in "healthy years" experienced by our aging population. Consequently, many scientists focus their research on understanding the process of aging and trialing interventions that can promote healthspan. The 2021 Midwest Aging Consortium consensus statement is to develop and further the understanding of aging and age-related disease using the wealth of expertise across universities in the Midwestern United States. This report summarizes the cutting-edge research covered in a virtual symposium held by a consortium of researchers in the Midwestern United States, spanning topics such as senescence biomarkers, serotonin-induced DNA protection, immune system development, multisystem impacts of aging, neural decline following severe infection, the unique transcriptional impact of calorie restriction of different fat depots, the pivotal role of fasting in calorie restriction, the impact of peroxisome dysfunction, and the influence of early life trauma on health. The symposium speakers presented data from studies conducted in a variety of common laboratory animals as well as less-common species, including Caenorhabditis elegans, Drosophila, mice, rhesus macaques, elephants, and humans. The consensus of the symposium speakers is that this consortium highlights the strength of aging research in the Midwestern United States as well as the benefits of a collaborative and diverse approach to geroscience.

Very-low-protein diets lead to reduced food intake and weight loss, linked to inhibition of hypothalamic mTOR signaling, in mice

The protein leverage hypothesis predicts that low dietary protein should increase energy intake and cause adiposity. We designed 10 diets varying from 1% to 20% protein combined with either 60% or 20% fat. Contrasting the expectation, very low protein did not cause increased food intake. Although these mice had activated hunger signaling, they ate less food, resulting in decreased body weight and improved glucose tolerance but not increased frailty, even under 60% fat. Moreover, they did not show hyperphagia when returned to a 20% protein diet, which could be mimicked by treatment with rapamycin. Intracerebroventricular injection of AAV-S6K1 significantly blunted the decrease in both food intake and body weight in mice fed 1% protein, an effect not observed with inhibition of eIF2a, TRPML1, and Fgf21 signaling. Hence, the 1% protein diet induced decreased food intake and body weight via a mechanism partially dependent on hypothalamic mTOR signaling.

The adverse metabolic effects of branched-chain amino acids are mediated by isoleucine and valine

Low-protein diets promote metabolic health in rodents and humans, and the benefits of low-protein diets are recapitulated by specifically reducing dietary levels of the three branched-chain amino acids (BCAAs), leucine, isoleucine, and valine. Here, we demonstrate that each BCAA has distinct metabolic effects. A low isoleucine diet reprograms liver and adipose metabolism, increasing hepatic insulin sensitivity and ketogenesis and increasing energy expenditure, activating the FGF21-UCP1 axis. Reducing valine induces similar but more modest metabolic effects, whereas these effects are absent with low leucine. Reducing isoleucine or valine rapidly restores metabolic health to diet-induced obese mice. Finally, we demonstrate that variation in dietary isoleucine levels helps explain body mass index differences in humans. Our results reveal isoleucine as a key regulator of metabolic health and the adverse metabolic response to dietary BCAAs and suggest reducing dietary isoleucine as a new approach to treating and preventing obesity and diabetes.

Of Mice and Men: Impacts of Calorie Restriction on Metabolomics of the Cerebellum

The main purpose of research in mice is to explore metabolic changes in animal models and then predict or propose potential translational benefits in humans. Although some researchers in the brain research field have mentioned that the mouse experiments results still lack the complex neuroanatomy of humans, caution is required to interpret the findings. In mice, we observed in article seventeenth of the series of the effects of graded levels of calorie restriction, metabolomic changes in the cerebellum indicated activation of hypothalamocerebellar connections driven by hunger responses. Therefore, the purpose of the current perspective is to set this latest paper into a wider context of the physiological, behavioral, and molecular changes seen in these mice and to compare and contrast them with previous human studies.

Agonist-independent Gαz activity negatively regulates beta-cell compensation in a diet-induced obesity model of type 2 diabetes

The inhibitory G protein alpha-subunit (Gα_z) is an important modulator of beta-cell function. Full-body Gα_z-null mice are protected from hyperglycemia and glucose intolerance after long-term high-fat diet (HFD) feeding. In this study, at a time point in the feeding regimen where WT mice are only mildly glucose intolerant, transcriptomics analyses reveal islets from HFD-fed Gα_z KO mice have a dramatically altered gene expression pattern as compared with WT HFD-fed mice, with entire gene pathways not only being more strongly upregulated or downregulated versus control-diet fed groups but actually reversed in direction. Genes involved in the “pancreatic secretion” pathway are the most strongly differentially regulated: a finding that correlates with enhanced islet insulin secretion and decreased glucagon secretion at the study end. The protection of Gα_z-null mice from HFD-induced diabetes is beta-cell autonomous, as beta cell–specific Gα_z-null mice phenocopy the full-body KOs. The glucose-stimulated and incretin-potentiated insulin secretion response of islets from HFD-fed beta cell–specific Gα_z-null mice is significantly improved as compared with islets from HFD-fed WT controls, which, along with no impact of Gα_z loss or HFD feeding on beta-cell proliferation or surrogates of beta-cell mass, supports a secretion-specific mechanism. Gα_z is coupled to the prostaglandin EP3 receptor in pancreatic beta cells. We confirm the EP3γ splice variant has both constitutive and agonist-sensitive activity to inhibit cAMP production and downstream beta-cell function, with both activities being dependent on the presence of beta-cell Gα_z.

The Effects of Graded Levels of Calorie Restriction: XIV. Global Metabolomics Screen Reveals Brown Adipose Tissue Changes in Amino Acids, Catecholamines, and Antioxidants After Short-Term Restriction in C57BL/6 Mice

Animals undergoing calorie restriction (CR) often lower their body temperature to conserve energy. Brown adipose tissue (BAT) is stimulated through norepinephrine when rapid heat production is needed, as it is highly metabolically active due to the uncoupling of the electron transport chain from ATP synthesis. To better understand how BAT metabolism changes with CR, we used metabolomics to identify 883 metabolites that were significantly differentially expressed in the BAT of C57BL/6 mice, fed graded CR (10%, 20%, 30%, and 40% CR relative to their individual baseline intake), compared with mice fed ad libitum (AL) for 12 hours a day. Pathway analysis revealed that graded CR had an impact on the TCA cycle and fatty acid degradation. In addition, an increase in nucleic acids and catecholamine pathways was seen with graded CR in the BAT metabolome. We saw increases in antioxidants with CR, suggesting a beneficial effect of mitochondrial uncoupling. Importantly, the instigator of BAT activation, norepinephrine, was increased with CR, whereas its precursors l-tyrosine and dopamine were decreased, indicating a shift of metabolites through the activation pathway. Several of these key changes were correlated with food anticipatory activity and body temperature, indicating BAT activation may be driven by responses to hunger.

Sarcosine Is Uniquely Modulated by Aging and Dietary Restriction in Rodents and Humans

A hallmark of aging is a decline in metabolic homeostasis, which is attenuated by dietary restriction (DR). However, the interaction of aging and DR with the metabolome is not well understood. We report that DR is a stronger modulator of the rat metabolome than age in plasma and tissues. A comparative metabolomic screen in rodents and humans identified circulating sarcosine as being similarly reduced with aging and increased by DR, while sarcosine is also elevated in long-lived Ames dwarf mice. Pathway analysis in aged sarcosine-replete rats identify this biogenic amine as an integral node in the metabolome network. Finally, we show that sarcosine can activate autophagy in cultured cells and enhances autophagic flux in vivo, suggesting a potential role in autophagy induction by DR. Thus, these data identify circulating sarcosine as a biomarker of aging and DR in mammalians and may contribute to age-related alterations in the metabolome and in proteostasis.

The Effects of Graded Levels of Calorie Restriction: XIII. Global Metabolomics Screen Reveals Graded Changes in Circulating Amino Acids, Vitamins, and Bile Acids in the Plasma of C57BL/6 Mice

Calorie restriction (CR) remains the most robust intervention to extend life span and improve health span. Using a global mass spectrometry–based metabolomics approach, we identified metabolites that were significantly differentially expressed in the plasma of C57BL/6 mice, fed graded levels of calorie restriction (10% CR, 20% CR, 30% CR, and 40% CR) compared with mice fed ad libitum for 12 hours a day. The differential expression of metabolites increased with the severity of CR. Pathway analysis revealed that graded CR had an impact on vitamin E and vitamin B levels, branched chain amino acids, aromatic amino acids, and fatty acid pathways. The majority of amino acids correlated positively with fat-free mass and visceral fat mass, indicating a strong relationship with body composition and vitamin E metabolites correlated with stomach and colon size, which may allude to the beneficial effects of investing in gastrointestinal organs with CR. In addition, metabolites that showed a graded effect, such as the sphinganines, carnitines, and bile acids, match our previous study on liver, which suggests not only that CR remodels the metabolome in a way that promotes energy efficiency, but also that some changes are conserved across tissues.

The Effects of Graded Levels of Calorie Restriction: X. Transcriptomic Responses of Epididymal Adipose Tissue

Calorie restriction (CR) leads to a remarkable decrease in adipose tissue mass and increases longevity in many taxa. Since the discovery of leptin, the secretory abilities of adipose tissue have gained prominence in the responses to CR. We quantified transcripts of epididymal white adipose tissue of male C57BL/6 mice exposed to graded levels of CR (0–40% CR) for 3 months. The numbers of differentially expressed genes (DEGs) involved in NF-κB, HIF1-α, and p53 signaling increased with increasing levels of CR. These pathways were all significantly downregulated at 40% CR relative to 12 h ad libitum feeding. In addition, graded CR had a substantial impact on DEGs associated with pathways involved in angiogenesis. Of the 497 genes differentially expressed with graded CR, 155 of these genes included a signal peptide motif. These putative signaling proteins were involved in the response to ketones, TGF-β signaling, negative regulation of insulin secretion, and inflammation. This accords with the previously established effects of graded CR on glucose homeostasis in the same mice. Overall these data suggest reduced levels of adipose tissue under CR may contribute to the protective impact of CR in multiple ways linked to changes in a large population of secreted proteins.

The Metabolic Response to a Low Amino Acid Diet is Independent of Diet-Induced Shifts in the Composition of the Gut Microbiome

Obesity and type 2 diabetes are increasing in prevalence around the world, and there is a clear need for new and effective strategies to promote metabolic health. A low protein (LP) diet improves metabolic health in both rodents and humans, but the mechanisms that underlie this effect remain unknown. The gut microbiome has recently emerged as a potent regulator of host metabolism and the response to diet. Here, we demonstrate that a LP diet significantly alters the taxonomic composition of the gut microbiome at the phylum level, altering the relative abundance of Actinobacteria, Bacteroidetes, and Firmicutes. Transcriptional profiling suggested that any impact of the microbiome on liver metabolism was likely independent of the microbiome-farnesoid X receptor (FXR) axis. We therefore tested the ability of a LP diet to improve metabolic health following antibiotic ablation of the gut microbiota. We found that a LP diet promotes leanness, increases energy expenditure, and improves glycemic control equally well in mice treated with antibiotics as in untreated control animals. Our results demonstrate that the beneficial effects of a LP diet on glucose homeostasis, energy balance, and body composition are unlikely to be mediated by diet-induced changes in the taxonomic composition of the gut microbiome.

Regulation of metabolic health by essential dietary amino acids

Although the beneficial effects of calorie restriction (CR) on health and aging were first observed a century ago, the specific macronutrients and molecular processes that mediate the effect of CR have been heavily debated. Recently, it has become clear that dietary protein plays a key role in regulating both metabolic health and longevity, and that both the quantity and quality - the specific amino acid composition - of dietary protein mediates metabolic health. Here, we discuss recent findings in model organisms ranging from yeast to mice and humans regarding the influence of dietary protein as well as specific amino acids on metabolic health, and the physiological and molecular mechanisms which may mediate these effects. We then discuss recent findings which suggest that the restriction of specific dietary amino acids may be a potent therapy to treat or prevent metabolic syndrome. Finally, we discuss the potential for dietary restriction of specific amino acids - or pharmaceuticals which harness these same mechanisms - to promote healthy aging.

The effects of graded levels of calorie restriction: V. Impact of short term calorie and protein restriction on physical activity in the C57BL/6 mouse

Calorie restriction (CR) delays the onset of age-related disease and extends lifespan in a number of species. When faced with reduced energy supply animals need to lower energy demands, which may be achieved in part by reducing physical activity (PA). We monitored changes in PA using implanted transmitters in male C57BL/6 mice in response to graded levels of CR (10 to 40%) or matched levels of graded protein restriction (PR) for 3 months. Mice were fed at lights out and ad libitum controls were limited to dark-phase feeding (12AL) or 24hr/day. Total daily PA declined in a non-linear manner over the first 30 days of CR or PR, remaining stable thereafter. Total daily PA was not related to the level of CR or PR. Total daily PA over the last 20 days of restriction was related to circulating leptin, insulin, tumor necrosis factor-α (TNF-α) and insulin-like growth factor (IGF)-1 levels, measured after 3 months. Mice under restriction showed a high level of activity in the 2hrs before feeding (food anticipatory activity: FAA). FAA followed a complex pattern, peaking around day 20, falling on ∼day 37 then increasing again. FAA was also positively related to the level of restriction and inversely to leptin, insulin, TNF-α and IGF-1. Non-FAA, in contrast, declined over the period of restriction, generally more so in mice under greater restriction, thereby offsetting to some extent the increase in FAA. Mice under PR displayed no changes in PA over time or in comparison to 12AL, and showed no increase in FAA.

The effects of graded levels of calorie restriction: VI. Impact of short-term graded calorie restriction on transcriptomic responses of the hypothalamic hunger and circadian signaling pathways

Food intake and circadian rhythms are regulated by hypothalamic neuropeptides and circulating hormones, which could mediate the anti‐ageing effect of calorie restriction (CR). We tested whether these two signaling pathways mediate CR by quantifying hypothalamic transcripts of male C57BL/6 mice exposed to graded levels of CR (10 % to 40 %) for 3 months. We found that the graded CR manipulation resulted in upregulation of core circadian rhythm genes, which correlated negatively with circulating levels of leptin, insulin‐like growth factor 1 (IGF‐1), insulin, and tumor necrosis factor alpha (TNF‐α). In addition, key components in the hunger signaling pathway were expressed in a manner reflecting elevated hunger at greater levels of restriction, and which also correlated negatively with circulating levels of insulin, TNF‐α, leptin and IGF‐1. Lastly, phenotypes, such as food anticipatory activity and body temperature, were associated with expression levels of both hunger genes and core clock genes. Our results suggest modulation of the hunger and circadian signaling pathways in response to altered levels of circulating hormones, that are themselves downstream of morphological changes resulting from CR treatment, may be important elements in the response to CR, driving some of the key phenotypic outcomes.

The effects of graded levels of calorie restriction: VIII. Impact of short term calorie and protein restriction on basal metabolic rate in the C57BL/6 mouse

Under calorie restriction (CR) animals need to lower energy demands. Whether this involves a reduction in cellular metabolism is an issue of contention. We exposed C57BL/6 mice to graded CR for 3 months, measured BMR and dissected out 20 body compartments. From a separate age-matched group (n=57), we built 7 predictive models for BMR. Unadjusted BMR declined with severity of restriction. Comparison of measured and predicted BMR from the simple models suggested suppression occurred. The extent of 'suppression' was greater with increased CR severity. However, when models based on individual organ sizes as predictors were used, the discrepancy between the prediction and the observed BMR disappeared. This suggested 'metabolic suppression' was an artefact of not having a detailed enough model to predict the expected changes in metabolism. Our data have wide implications because they indicate that inferred 'metabolic' impacts of genetic and other manipulations may reflect effects on organ morphology.

The effects of graded levels of calorie restriction: IX. Global metabolomic screen reveals modulation of carnitines, sphingolipids and bile acids in the liver of C57BL/6 mice

Calorie restriction (CR) remains the most robust intervention to extend lifespan and improve health span. Using a global mass spectrometry-based metabolomic approach, we identified 193 metabolites that were significantly differentially expressed (SDE) in the livers of C57BL/6 mice, fed graded levels of CR (10, 20, 30 and 40% CR) compared to mice fed ad libitum for 12 h a day. The differential expression of metabolites also varied with the different feeding groups. Pathway analysis revealed that graded CR had an impact on carnitine synthesis and the carnitine shuttle pathway, sphingosine-1-phosphate (S1P) signalling and methionine metabolism. S1P, sphingomyelin and L-carnitine were negatively correlated with body mass, leptin, insulin-like growth factor- 1 (IGF-1) and major urinary proteins (MUPs). In addition, metabolites which showed a graded effect, such as ceramide, S1P, taurocholic acid and L-carnitine, responded in the opposite direction to previously observed age-related changes. We suggest that the modulation of this set of metabolites may improve liver processes involved in energy release from fatty acids. S1P also negatively correlated with catalase activity and body temperature, and positively correlated with food anticipatory activity. Injecting mice with S1P or an S1P receptor 1 agonist did not precipitate changes in body temperature, physical activity or food intake suggesting that these correlations were not causal relationships.

The effects of graded levels of calorie restriction: III. Impact of short term calorie and protein restriction on mean daily body temperature and torpor use in the C57BL/6 mouse

A commonly observed response in mammals to calorie restriction (CR) is reduced body temperature (T_b). We explored how the T_b of male C57BL/6 mice responded to graded CR (10 to 40%), compared to the response to equivalent levels of protein restriction (PR) over 3 months. Under CR there was a dynamic change in daily T_b over the first 30–35 days, which stabilized thereafter until day 70 after which a further decline was noted. The time to reach stability was dependent on restriction level. Body mass negatively correlated with T_b under ad libitum feeding and positively correlated under CR. The average T_b over the last 20 days was significantly related to the levels of body fat, structural tissue, leptin and insulin-like growth factor-1. Some mice, particularly those under higher levels of CR, showed periods of daily torpor later in the restriction period. None of the changes in T_b under CR were recapitulated by equivalent levels of PR. We conclude that changes in T_b under CR are a response only to the shortfall in calorie intake. The linear relationship between average T_b and the level of restriction supports the idea that T_b changes are an integral aspect of the lifespan effect.

Inducible T-cell co-stimulator ligand (ICOSL) blockade leads to selective inhibition of anti-KLH IgG responses in subjects with systemic lupus erythematosus

Objectives

To evaluate the safety, tolerability, pharmacokinetics (PK) and pharmacodynamics (PD) of single-dose and multiple-dose administration of AMG 557, a human anti-inducible T cell co-stimulator ligand (ICOSL) monoclonal antibody, in subjects with systemic lupus erythematosus (SLE).

Methods

Patients with mild, stable SLE (n=112) were enrolled in two clinical trials to evaluate the effects of single (1.8–210 mg subcutaneous or 18 mg intravenous) and multiple (6 –210 mg subcutaneous every other week (Q2W)×7) doses of AMG 557. Subjects received two 1 mg intradermal injections 28 days apart of keyhole limpet haemocyanin (KLH), a neoantigen, to assess PD effects of AMG 557. Safety, PK, target occupancy, anti-KLH antibody responses, lymphocyte subset analyses and SLE-associated biomarkers and clinical outcomes were assessed.

Results

AMG 557 demonstrated an acceptable safety profile. The PK properties were consistent with an antibody directed against a cell surface target, with non-linear PK observed at lower concentrations and linear PK at higher concentrations. Target occupancy by AMG 557 was dose dependent and reversible, and maximal occupancy was achieved in the setting of this trial. Anti-AMG 557 antibodies were observed, but none were neutralising and without impact on drug levels. A significant reduction in the anti-KLH IgG response was observed with AMG 557 administration without discernible changes in the anti-KLH IgM response or on the overall IgG levels. No discernible changes were seen in lymphocyte subsets or in SLE-related biomarkers and clinical measures.

Conclusions

The selective reduction in anti-KLH IgG demonstrates a PD effect of AMG 557 in subjects with SLE consistent with the biology of the ICOS pathway and supports further studies of AMG 557 as a potential therapeutic for autoimmune diseases.

Trial registration numbers

NCT02391259 and NCT00774943.

A longitudinal analysis of the effects of age on the blood plasma metabolome in the common marmoset, Callithrix jacchus

Primates tend to be long-lived for their size with humans being the longest lived of all primates. There are compelling reasons to understand the underlying age-related processes that shape human lifespan. But the very fact of our long lifespan that makes it so compelling, also makes it especially difficult to study. Thus, in studies of aging, researchers have turned to non-human primate models, including chimpanzees, baboons, and rhesus macaques. More recently, the common marmoset, Callithrix jacchus, has been recognized as a particularly valuable model in studies of aging, given its small size, ease of housing in captivity, and relatively short lifespan. However, little is known about the physiological changes that occur as marmosets age. To begin to fill in this gap, we utilized high sensitivity metabolomics to define the longitudinal biochemical changes associated with age in the common marmoset. We measured 2104 metabolites from blood plasma at three separate time points over a 17-month period, and we completed both a cross-sectional and longitudinal analysis of the metabolome. We discovered hundreds of metabolites associated with age and body weight in both male and female animals. Our longitudinal analysis identified age-associated metabolic pathways that were not found in our cross-sectional analysis. Pathways enriched for age-associated metabolites included tryptophan, nucleotide, and xenobiotic metabolism, suggesting these biochemical pathways might play an important role in the basic mechanisms of aging in primates. Moreover, we found that many metabolic pathways associated with age were sex specific. Our work illustrates the power of longitudinal approaches, even in a short time frame, to discover novel biochemical changes that occur with age.

Results from the IQ-CSRC prospective study support replacement of the thorough QT study by QT assessment in the early clinical phase

The QT effects of five "QT-positive" and one negative drug were tested to evaluate whether exposure-response analysis can detect QT effects in a small study with healthy subjects. Each drug was given to nine subjects (six for placebo) in two dose levels; positive drugs were chosen to cause 10 to 12 ms and 15 to 20 ms QTcF prolongation. The slope of the concentration/ΔQTc effect was significantly positive for ondansetron, quinine, dolasetron, moxifloxacin, and dofetilide. For the lower dose, an effect above 10 ms could not be excluded, i.e., the upper bound of the confidence interval for the predicted mean ΔΔQTcF effect was above 10 ms. For the negative drug, levocetirizine, a ΔΔQTcF effect above 10 ms was excluded at 6-fold the therapeutic dose. The study provides evidence that robust QT assessment in early-phase clinical studies can replace the thorough QT study.

Safety of intravenous antibiotic therapy in patients referred for treatment of neurologic Lyme disease

AIM

Although intravenous antibiotic therapy is recommended for neurologic Lyme disease, safety concerns have been raised about treatment beyond 30 days in patients with persistent neurologic symptoms. The goal of our study was to evaluate the safety of extended intravenous antibiotic therapy in patients referred for treatment of neurologic Lyme disease.

METHODS

We enrolled 200 consecutive patients with significant neurologic symptoms and positive testing for Borrelia burgdorferi. Patients were treated with intravenous antibiotics using various intravascular devices (IVDs). Standard IVD care was administered to all patients, and monitoring for medication reactions and IVD complications was performed on a weekly basis.

RESULTS

The mean length of intravenous antibiotic treatment was 118 days (range, 7-750 days) representing 23,654 IVD-days. Seven patients (3.5%) experienced allergic reactions to the antibiotic medication, and two patients (1.0%) had gallbladder toxicity. IVD complications occurred in 15 patients (7.5%) representing an incidence of 0.63 per 1,000 IVD-days. The IVD problems occurred an average of 81 days after initiation of treatment (range, 7-240 days). There were six suspected line infections for an incidence of 0.25 per 1,000 IVD-days. Only one of the IVD infections was confirmed, and no resistant organisms were cultured from any patient. None of the IVD complications were fatal.

CONCLUSION

Prolonged intravenous antibiotic therapy is associated with low morbidity and no IVD-related mortality in patients referred for treatment of neurologic Lyme disease. With proper IVD care, the risk of extended antibiotic therapy in these patients appears to be low.

Modulation of intestinal gene expression by dietary zinc status: effectiveness of cDNA arrays for expression profiling of a single nutrient deficiency

Mammalian nutritional status affects the homeostatic balance of multiple physiological processes and their associated gene expression. Although DNA array analysis can monitor large numbers of genes, there are no reports of expression profiling of a micronutrient deficiency in an intact animal system. In this report, we have tested the feasibility of using cDNA arrays to compare the global changes in expression of genes of known function that occur in the early stages of rodent zinc deficiency. The gene-modulating effects of this deficiency were demonstrated by real-time quantitative PCR measurements of altered mRNA levels for metallothionein 1, zinc transporter 2, and uroguanylin, all of which have been previously documented as zinc-regulated genes. As a result of the low level of inherent noise within this model system and application of a recently reported statistical tool for statistical analysis of microarrays [Tusher, V.G., Tibshirani, R. & Chu, G. (2001) Proc. Natl. Acad. Sci. USA 98, 5116-5121], we demonstrate the ability to reproducibly identify the modest changes in mRNA abundance produced by this single micronutrient deficiency. Among the genes identified by this array profile are intestinal genes that influence signaling pathways, growth, transcription, redox, and energy utilization. Additionally, the influence of dietary zinc supply on the expression of some of these genes was confirmed by real-time quantitative PCR. Overall, these data support the effectiveness of cDNA array expression profiling to investigate the pleiotropic effects of specific nutrients and may provide an approach to establishing markers for assessment of nutritional status.

Integrative noetic therapies as adjuncts to percutaneous intervention during unstable coronary syndromes: Monitoring and Actualization of Noetic Training (MANTRA) feasibility pilot

BACKGROUND

Patients undergoing percutaneous coronary intervention (PCI) for unstable coronary syndromes have substantial emotional and spiritual distress that may promote procedural complications. Noetic (nonpharmacologic) therapies may reduce anxiety, pain and distress, enhance the efficacy of pharmacologic agents, or affect short- and long-term procedural outcomes.

METHODS

The Monitoring and Actualization of Noetic Training (MANTRA) pilot study examined the feasibility of applying 4 noetic therapies-stress relaxation, imagery, touch therapy, and prayer-to patients in the setting of acute coronary interventions. Eligible patients had acute coronary syndromes and invasive angiography or PCI. Patients were randomized across 5 treatment groups: the 4 noetic and standard therapies. Questionnaires completed before PCI reflected patients' religious beliefs and anxiety. Index hospitalization end points included post-PCI ischemia, death, myocardial infarction, heart failure, and urgent revascularization. Mortality was followed up for 6 months after hospitalization.

RESULTS

Of eligible patients, 88% gave informed consent. Of 150 patients enrolled, 120 were assigned to noetic therapy; 118 (98%) completed their therapeutic assignments. All clinical end points were available for 100% of patients. Results were not statistically significant for any outcomes comparisons. There was a 25% to 30% absolute reduction in adverse periprocedural outcomes in patients treated with any noetic therapy compared with standard therapy. The lowest absolute complication rates were observed in patients assigned to off-site prayer. All mortality by 6-month follow-up was in the noetic therapies group. In patients with questionnaire scores indicating a high level of spiritual belief, a high level of personal spiritual activity, a low level of community-based religious involvement, or a high level of anxiety, noetic therapies appeared to show greater reduction in absolute in-hospital complication rates compared with standard therapy.

CONCLUSIONS

Acceptance of noetic adjuncts to invasive therapy for acute coronary syndromes was excellent, and logistics were feasible. No outcomes differences were significant; however, index hospitalization data consistently suggested a therapeutic benefit with noetic therapy. Of all noetic therapies, off-site intercessory prayer had the lowest short- and long-term absolute complication rates. Definitive demonstration of treatment effects of this magnitude would be feasible in a patient population about 4 times that of this pilot study. Absolute mortality differences make safety considerations a mandatory feature of future clinical trials in this area.

The genome of the Queensland fruit fly Bactrocera tryoni contains multiple representatives of the mariner family of transposable elements

Representatives of five distinct types of transposable elements of the mariner family were detected in the genomes of the Queensland fruit fly Bactrocera tryoni and its sibling species Bactrocera neohumeralis by phylogenetic analysis of transposase gene fragments. Three mariner types were also found in an additional tephritid, Bactrocera jarvisi. Using genomic library screening and inverse PCR, full-length elements representing the mellifera subfamily (B. tryoni.mar1) and the irritans subfamily (B. tryoni.mar2) were isolated from the B. tryoni genome. Nucleotide consensus sequences for each type were derived from multiple defective copies. Predicted transposase sequences share approximately 23% amino acid identity. B. tryoni.mar1 elements have an estimated copy number of about 900 in the B. tryoni genome, whereas B. tryoni.mar2 element types appear to be present in low copy number.

ST-Segment recovery adds to the assessment of TIMI 2 and 3 flow in predicting infarct wall motion after thrombolytic therapy

BACKGROUND

Early resolution of ST-segment elevation (ST-segment recovery) is associated with an improved outcome after infarction. Whether this relation is present in patients with Thrombolysis In Myocardial Infarction (TIMI) grade 2 or 3 flow (ie, patent) infarct-related arteries is not known.

METHODS AND RESULTS

To examine the associations between time to achieve stable 50% ST-segment recovery assessed by continuous ECG monitoring, infarct artery flow, and infarct zone wall motion (at 48 hours), we studied 134 patients who underwent angiography at 99 (interquartile range 92 to 110) minutes after commencing streptokinase, initiated within 12 hours of onset of symptoms of myocardial infarction. Patients with TIMI 2 or 3 flow who failed to achieve early stable ST-segment recovery (50% ST-segment recovery sustained for > or 4 hours with <100 microV change in the peak lead) by 60 or 90 minutes had a higher fraction of chords in the infarct zone >2 SD below normal wall motion (TIMI 2: 55.5% vs 15.3%, P=0.006; and 56.5% vs 26.8%, P=0.01, respectively; and TIMI 3: 48.8% vs 28.3%, P=0.07; and 51.8% vs 29.9%, P=0.03, respectively). Time to stable ST-segment recovery was a multivariate predictor of infarct zone wall motion (P=0.04) independent of TIMI flow grade and the time from symptom onset to streptokinase therapy.

CONCLUSIONS

In patients with TIMI 2 or 3 flow in infarct-related artery, early stable ST-segment recovery is associated with improved infarct zone wall motion at 48 hours. ST-segment recovery may provide additional information about the degree of myocyte reperfusion achieved in patients with a patent epicardial infarct-related artery after thrombolytic therapy.

Granulocyte-colony stimulating factor mobilizes T helper 2-inducing dendritic cells

Peripheral blood stem cells (PBSC) obtained from granulocyte-colony stimulating factor (G-CSF)-mobilized donors are increasingly used for allogeneic transplantation. Despite a 10-fold higher dose of transplanted T cells, acute graft-versus-host disease (GVHD) does not develop in higher proportion in recipients of PBSC than in recipients of marrow. T cells from G-CSF-treated experimental animals preferentially produce IL-4 and IL-10, cytokines characteristic of Th2 responses, which are associated with diminished GVHD-inducing ability. We hypothesized that G-CSF-mobilized PBSC contain antigen-presenting cells, which prime T-lymphocytes to produce Th2 cytokines. Two distinct lineages of dendritic cells (DC) have been described in humans, DC1 and DC2, according to their ability to induce naive T-cell differentiation to Th1 and Th2 effector cells, respectively. We have used multicolor microfluorometry to enumerate DC1 and DC2 in the peripheral blood of normal donors. G-CSF treatment with 10 to 16 microg/kg per day for 5 days increased peripheral blood DC2 counts from a median of 4.9 x 10(6)/L to 24.8 x 10(6)/L (P =.0009), whereas DC1 counts did not change. Purified DC1, from either untreated or G-CSF treated donors, induced the proliferation of allogeneic naive T cells, but fresh DC2 were poor stimulators. Tumor necrosis factor-alpha (TNF-alpha)-activated DC1 induced allogeneic naive T cells to produce IFN-gamma, which is typical of Th1 responses, whereas TNF-alpha-activated DC2 induced allogeneic naive T cells to produce IL-4 and IL-10, which are typical of Th2 responses. PBSC transplants contained higher doses of DC2 than marrow transplants (median, 2.4 x 10(6)/kg versus 0.5 x 10(6)/kg) (P =.006), whereas the dose of DC1 was comparable. Thus, it is conceivable that transplantation of G-CSF-stimulated PBSC does not result in overwhelming acute GVHD because the graft contains predominantly Th2-inducing DC. Adoptive transfer of purified DC2 may be exploited to induce immune deviation after transplantation of hematopoietic stem cells or organ allografts. (Blood. 2000;95:2484-2490)

Myocardial ischemia correlates with reduced fibrinolytic activity following peripheral vascular surgery

STUDY OBJECTIVES

To evaluate the relationship between perioperative ischemia and serial concentrations of D-dimer, which is a sensitive and specific marker of fibrinolytic activity. Myocardial ischemia and infarction are well-recognized complications of peripheral vascular surgery. We hypothesized that patients at increased risk of perioperative myocardial ischemia might be identified preoperatively by abnormal hemostatic indices.

DESIGN

Prospective clinical outcomes study.

SETTING

A 1,124-bed tertiary care medical center.

PATIENTS

42 ASA physical status II, III, and IV patients undergoing peripheral vascular surgery.

INTERVENTIONS

Serial D-dimer concentrations were measured preoperatively, and at 24 and 72 hours postoperatively. Continuous 12-lead ST-segment monitoring (Mortara Instrument, Inc., Milwaukee, WI) was performed with the acquisition of a 12-lead ECG every 20 seconds for 72 hours.

MEASUREMENTS AND MAIN RESULTS

D-dimer measurements were performed in duplicate using the Dimer Gold assay (American Diagnostica, Greenwich CT). Ischemic episodes, as defined by continuous 12-lead ST-segment monitoring, occurred in 49% of patients. There were no demographic differences between ischemic and nonischemic groups. Although baseline D-dimer concentrations were not statistically significantly different between groups, patients experiencing perioperative myocardial ischemia generated significantly less D-dimer during the perioperative period (p = 0. 014).

CONCLUSIONS

PATIENTS with an impaired fibrinolytic response, as defined by reduced generation of D-dimer, experienced an increased incidence of perioperative myocardial ischemia.

Prognostic implications of TIMI flow grade in the infarct related artery compared with continuous 12-lead ST-segment resolution analysis. Reexamining the "gold standard" for myocardial reperfusion assessment

OBJECTIVE

To compare the prognostic significance of reperfusion assessment by Thrombolysis in Myocardial Infarction (TIMI) flow grade in the infarct related artery and ST-segment resolution analysis, by correlating with clinical outcomes in patients with acute myocardial infarction (AMI).

BACKGROUND

Angiographic assessment, based on epicardial coronary anatomy, has been considered the "gold standard" for reperfusion. The electrocardiogram (ECG) monitoring provides a noninvasive, real-time physiologic marker of cellular reperfusion and may better predict clinical outcomes.

METHODS

Two hundred fifty-eight AMI patients from the Thrombolytics and Myocardia Infarction phase 7 and Global Utilization of Streptokinase tPA for Occluded coronary arteries phase 1 trials were stratified based on blinded, simultaneous reperfusion assessment on the acute angiogram (divided into TIMI grades 0 & 1, TIMI grade 2 and TIMI grade 3) and ST-segment resolution analysis (divided into: <50% ST-segment elevation resolution or reelevation and > or =50% ST-segment elevation resolution). In-hospital mortality, congestive heart failure (CHF) and combined mortality or CHF were compared to determine the prognostic significance of reperfusion assessment by each modality using chi-square and Fisher's Exact tests for univariable correlation and logistic regression analysis for univariable and multivariable prediction models.

RESULTS

By logistic regression analysis, ST-segment resolution patterns were an independent predictor of the combined outcome of mortality or CHF (p = 0.024), whereas TIMI flow grade was not (p = 0.693). Among the patients determined to have failed reperfusion by TIMI flow grade assessment (TIMI flow grade 0 & 1), the ST-segment resolution of > or =50% identified a subgroup with relatively benign outcomes with the incidence of the combined end point of mortality or CHF 17.2% versus 37.2% in those without ST-segment resolution (p = 0.06).

CONCLUSION

Continuous 12-lead ECG monitoring can be an inexpensive and reliable modality for monitoring nutritive reperfusion status and to obtain prognostic information in patients with AMI.

Neurosurgical evacuation of intracranial hemorrhage after thrombolytic therapy for acute myocardial infarction: experience from the GUSTO-I trial. Global Utilization of Streptokinase and tissue-plasminogen activator (tPA) for Occluded Coronary Arteries

BACKGROUND

Intracranial hemorrhage is an uncommon but very dangerous complication in patients receiving thrombolytic therapy for acute myocardial infarction. Neurosurgical evacuation is often an available treatment option. However, the association between neurosurgical evacuation and clinical outcomes in these patients has yet to be determined.

METHODS

The GUSTO-I trial randomly assigned 41,021 patients with acute myocardial infarction to 1 of 4 thrombolytic strategies in 1081 hospitals in 15 countries. A total of 268 patients (0.65%) had an intracranial hemorrhage. We assessed differences in clinical characteristics, neuroimaging features, Glasgow coma scale scores, functional status (disabled: moderate or severe deficit; not disabled: no or minor deficit) and 30-day mortality rate between the 46 patients who underwent neurosurgical evacuation and the 222 patients who did not.

RESULTS

Mortality rate at 30 days for all patients with intracranial hemorrhage was 60%; an additional 27% were disabled. Evacuation was associated with significantly higher 30-day survival (65% versus 35%, P <.001) and a trend toward improved functional status (nondisabling stroke: 20% versus 12%, P =.15).

CONCLUSIONS

Although intracranial hemorrhage is uncommon after thrombolysis for acute myocardial infarction, 87% of patients die or have disabling stroke. Although not definitive, these data indicate that neurosurgical evacuation may be associated with improved clinical outcomes. Physicians treating such patients should consider early neurosurgical consultation and intervention in these patients.

Relationship between casein kinase I isoforms and a neurofilament-associated kinase

Purified neurofilaments (NFs) contain an associated kinase (NFAK) activity that phosphorylates selectively a subset of sites in the tail of NF-M and has properties consistent with casein kinase I (CKI). Because CKI consists of a family of as many as seven genes (alpha, beta, gamma1-3, delta, and epsilon), we investigated the extent to which different CKI isoforms contribute to NFAK activity. Using an NF-M-derived substrate, we determined that NFAK activity copurified with casein kinase activity through two purification steps. In an in-gel kinase assay, NFAK activity occurred at 36-40 kDa, corresponding to the size of CKIalpha isoforms. Chicken neurons express transcripts encoding four alternatively spliced variants of CKIalpha (CKIalpha, CKIalphaS, CKIalphaL, and CKIalphaLS) differing in the presence or absence of two inserts, L and S. Using antibodies against different isoforms or with broad CKI specificity, we determined that all four CKIalpha variants, as well as other CKI family members, are present in chicken brain. However, only CKIalpha and CKIalphaS could be detected in purified NFAK. Also, immunoprecipitation studies showed that CKIalpha and CKIalphaS together account for NFAK activity. These findings raise the possibility that only a subset of CKI isoforms may be able to associate with and/or phosphorylate NFs.

Comparison of slow oscillating versus fast balloon inflation strategies for coronary angioplasty

Previous studies suggest that slow and/or oscillating balloon inflation during coronary angioplasty may decrease the incidence of coronary dissection and improve clinical outcomes. To compare the effect of slow oscillating versus conventional fast inflation techniques on the incidence of severe coronary dissection during angioplasty, 622 patients were randomized to slow oscillating inflation versus fast inflation. Angiographic outcomes of the procedures and in-hospital clinical events were recorded. The primary end point of severe (type C, D, E, F) dissection occurred in 7.7% of patients undergoing slow oscillation and 6.6% of patients undergoing fast inflation (p = 0.87). Major complications (death, urgent coronary artery bypass graft surgery, stroke, abrupt closure, or Q-wave myocardial infarction) occurred in 4.7% of patients undergoing slow oscillation and 3.5% of patients undergoing fast inflation (p = 0.45). The 2 inflation strategies did not differ in the pressure at which the balloon achieved full expansion, angiographic success rate, residual stenosis, and incidence of all minor and/or major complications. We conclude that there is no benefit of slow oscillating inflation over routine fast inflation in angioplasty. Slow oscillating inflation did not dilate lesions at lower pressures, decrease the incidence of dissection or severe dissection, or reduce the incidence of adverse clinical outcomes.