Molecular signatures of cortical expansion in the human fetal brain

The third trimester of human gestation is characterised by rapid increases in brain volume and cortical surface area. A growing catalogue of cells in the prenatal brain has revealed remarkable molecular diversity across cortical areas.1,2 Despite this, little is known about how this translates into the patterns of differential cortical expansion observed in humans during the latter stages of gestation. Here we present a new resource, μBrain, to facilitate knowledge translation between molecular and anatomical descriptions of the prenatal developing brain. Built using generative artificial intelligence, μBrain is a three-dimensional cellular-resolution digital atlas combining publicly-available serial sections of the postmortem human brain at 21 weeks gestation3 with bulk tissue microarray data, sampled across 29 cortical regions and 5 transient tissue zones.4 Using μBrain, we evaluate the molecular signatures of preferentially-expanded cortical regions during human gestation, quantified in utero using magnetic resonance imaging (MRI). We find that differences in the rates of expansion across cortical areas during gestation respect anatomical and evolutionary boundaries between cortical types5 and are founded upon extended periods of upper-layer cortical neuron migration that continue beyond mid-gestation. We identify a set of genes that are upregulated from mid-gestation and highly expressed in rapidly expanding neocortex, which are implicated in genetic disorders with cognitive sequelae. Our findings demonstrate a spatial coupling between areal differences in the timing of neurogenesis and rates of expansion across the neocortical sheet during the prenatal epoch. The μBrain atlas is available from: https://garedaba.github.io/micro-brain/ and provides a new tool to comprehensively map early brain development across domains, model systems and resolution scales.

Macronutrients effects on satiety and food intake in older and younger adults: A randomised controlled trial

Older adults are advised to increase their protein intake to maintain their muscle mass. However, protein is considered the most satiating macronutrient and this recommendation may cause a decrease in total energy intake. To date, satiety studies comparing all three macronutrients have been undertaken in young adults, and it is unclear if the same response is seen in older adults. The objective of this study was to compare the effect of preloads high in protein, fat, and carbohydrate but equal in energy (∼300 kcal) and volume (250 ml) on energy intake, perceived appetite, and gastric emptying in younger and older adults. Twenty older and 20 younger adults completed a single-blinded randomised crossover trial involving three study visits. Participants consumed a standard breakfast, followed by a preload milkshake high in either carbohydrate, fat, or protein. Three hours after the preload, participants were offered an ad libitum meal to assess food intake. Visual analogue scales were used to measure perceived appetite and gastric emptying was measured via the 13C-octanoic acid breath test. There was no significant effect of preload type or age on energy intake either at the ad libitum meal, self-recorded food intake for the rest of the test day or subjective appetite ratings. There was a significant effect of preload type on gastric emptying latency phase and ascension time, and an effect of age on gastric emptying latency and lag phase such that older adults had faster emptying. In conclusion, energy intake, and perceived appetite were not affected by macronutrient content of the preloads in both younger and older adults, but gastric emptying times differed.

Restoring polyamine levels by supplementation of spermidine modulates hepatic immune landscape in murine model of NASH

AIMS

To determine if changes in polyamines metabolism occur during non-alcoholic steatohepatitis (NASH) in human patients and mice, as well as to assess systemic and liver-specific effects of spermidine administration into mice suffering from advanced NASH.

MATERIALS AND METHODS

Human fecal samples were collected from 50 healthy and 50 NASH patients. For the preclinical studies C57Bl6/N male mice fed GAN or NIH-31 diet for 6 months were ordered from Taconic and liver biopsy was performed. Based on severity of liver fibrosis, body composition and body weight, the mice from both dietary groups were randomized into another two groups: half receiving 3 mM spermidine in drinking water, half normal water for subsequent 12 weeks. Body weight was measured weekly and glucose tolerance and body composition were assessed at the end. Blood and organs were collected during necropsy, and intrahepatic immune cells were isolated for flow cytometry analysis.

RESULTS

Metabolomic analysis of human and murine feces confirmed that levels of polyamines decreased along NASH progression. Administration of exogenous spermidine to the mice from both dietary groups did not affect body weight, body composition or adiposity. Moreover, incidence of macroscopic hepatic lesions was higher in NASH mice receiving spermidine. On the other hand, spermidine normalized numbers of Kupffer cells in the livers of mice suffering from NASH, although these beneficial effects did not translate into improved liver steatosis or fibrosis severity.

CONCLUSION

Levels of polyamines decrease during NASH in mice and human patients but spermidine administration does not improve advanced NASH.

FGF21 protects against hepatic lipotoxicity and macrophage activation to attenuate fibrogenesis in nonalcoholic steatohepatitis

Analogues of the hepatokine fibroblast growth factor 21 (FGF21) are in clinical development for type 2 diabetes and nonalcoholic steatohepatitis (NASH) treatment. Although their glucose-lowering and insulin-sensitizing effects have been largely unraveled, the mechanisms by which they alleviate liver injury have only been scarcely addressed. Here, we aimed to unveil the mechanisms underlying the protective effects of FGF21 on NASH using APOE*3-Leiden.CETP mice, a well-established model for human-like metabolic diseases. Liver-specific FGF21 overexpression was achieved in mice, followed by administration of a high-fat high-cholesterol diet for 23 weeks. FGF21 prevented hepatic lipotoxicity, accompanied by activation of thermogenic tissues and attenuation of adipose tissue inflammation, improvement of hyperglycemia and hypertriglyceridemia, and upregulation of hepatic programs involved in fatty acid oxidation and cholesterol removal. Furthermore, FGF21 inhibited hepatic inflammation, as evidenced by reduced Kupffer cell (KC) activation, diminished monocyte infiltration, and lowered accumulation of monocyte-derived macrophages. Moreover, FGF21 decreased lipid- and scar-associated macrophages, which correlated with less hepatic fibrosis as demonstrated by reduced collagen accumulation. Collectively, hepatic FGF21 overexpression limits hepatic lipotoxicity, inflammation, and fibrogenesis. Mechanistically, FGF21 blocks hepatic lipid influx and accumulation through combined endocrine and autocrine signaling, respectively, which prevents KC activation and lowers the presence of lipid- and scar-associated macrophages to inhibit fibrogenesis.

Peptide-YY3-36/glucagon-like peptide-1 combination treatment of obese diabetic mice improves insulin sensitivity associated with recovered pancreatic β-cell function and synergistic activation of discrete hypothalamic and brainstem neuronal circuitries

OBJECTIVE

Obesity-linked type 2 diabetes (T2D) is a worldwide health concern and many novel approaches are being considered for its treatment and subsequent prevention of serious comorbidities. Co-administration of glucagon like peptide 1 (Fc-GLP-1) and peptide YY_3-36 (Fc-PYY_3-36) renders a synergistic decrease in energy intake in obese men. However, mechanistic details of the synergy between these peptide agonists and their effects on metabolic homeostasis remain relatively scarce.

METHODS

In this study, we utilized long-acting analogues of GLP-1 and PYY_3-36 (via Fc-peptide conjugation) to better characterize the synergistic pharmacological benefits of their co-administration on body weight and glycaemic regulation in obese and diabetic mouse models. Hyperinsulinemic-euglycemic clamps were used to measure weight-independent effects of Fc-PYY_3-36 + Fc-GLP-1 on insulin action. Fluorescent light sheet microscopy analysis of whole brain was performed to assess activation of brain regions.

RESULTS

Co-administration of long-acting Fc-IgG/peptide conjugates of Fc-GLP-1 and Fc-PYY_3-36 (specific for PYY receptor-2 (Y2R)) resulted in profound weight loss, restored glucose homeostasis, and recovered endogenous β-cell function in two mouse models of obese T2D. Hyperinsulinemic-euglycemic clamps in C57BLKS/J db/db and diet-induced obese Y2R-deficient (Y2RKO) mice indicated Y2R is required for a weight-independent improvement in peripheral insulin sensitivity and enhanced hepatic glycogenesis. Brain cFos staining demonstrated distinct temporal activation of regions of the hypothalamus and hindbrain following Fc-PYY_3-36 + Fc-GLP-1R agonist administration.

CONCLUSIONS

These results reveal a therapeutic approach for obesity/T2D that improved insulin sensitivity and restored endogenous β-cell function. These data also highlight the potential association between the gut-brain axis in control of metabolic homeostasis.

Resolution of NASH and hepatic fibrosis by the GLP-1R/GcgR dual-agonist Cotadutide via modulating mitochondrial function and lipogenesis

Non-alcoholic fatty liver disease and steatohepatitis are highly associated with obesity and type 2 diabetes mellitus. Cotadutide, a GLP-1R/GcgR agonist, was shown to reduce blood glycemia, body weight and hepatic steatosis in patients with T2DM. Here, we demonstrate that the effects of Cotadutide to reduce body weight, food intake and improve glucose control are predominantly mediated through the GLP-1 signaling, while, its action on the liver to reduce lipid content, drive glycogen flux and improve mitochondrial turnover and function are directly mediated through Gcg signaling. This was confirmed by the identification of phosphorylation sites on key lipogenic and glucose metabolism enzymes in liver of mice treated with Cotadutide. Complementary metabolomic and transcriptomic analyses implicated lipogenic, fibrotic and inflammatory pathways, which are consistent with a unique therapeutic contribution of GcgR agonism by Cotadutide in vivo. Significantly, Cotadutide also alleviated fibrosis to a greater extent than Liraglutide or Obeticholic acid (OCA), despite adjusting dose to achieve similar weight loss in 2 preclinical mouse models of NASH. Thus Cotadutide, via direct hepatic (GcgR) and extra-hepatic (GLP-1R) effects, exerts multi-factorial improvement in liver function and is a promising therapeutic option for the treatment of steatohepatitis.

Combined loss of GLP-1R and Y2R does not alter progression of high-fat diet-induced obesity or response to RYGB surgery in mice

OBJECTIVE

Understanding the mechanisms underlying the remarkable beneficial effects of gastric bypass surgery is important for the development of non-surgical therapies or less invasive surgeries in the fight against obesity and metabolic disease. Although the intestinal L-cell hormones glucagon-like peptide-1 (GLP-1) and peptide tyrosine-tyrosine (PYY) have attracted the most attention, direct tests in humans and rodents with pharmacological blockade or genetic deletion of either the GLP1-receptor (GLP1R) or the Y2-receptor (Y2R) were unable to confirm their critical roles in the beneficial effects gastric bypass surgery on body weight and glucose homeostasis. However, new awareness of the power of combinatorial therapies in the treatment of metabolic disease would suggest that combined blockade of more than one signaling pathway may be necessary to reverse the beneficial effects of bariatric surgery.

METHODS

The metabolic effects of high-fat diet and the ability of Roux-en-Y gastric bypass surgery to lower food intake and body weight, as well as improve glucose handling, was tested in GLP1R and Y2R-double knockout (GLP1RKO/Y2RKO) and C57BL6J wildtype (WT) mice.

RESULTS

GLP1RKO/Y2RKO and WT mice responded similarly for up to 20 weeks on high-fat diet and 16 weeks after RYGB. There were no significant differences in loss of body and liver weight, fat mass, reduced food intake, relative increase in energy expenditure, improved fasting insulin, glucose tolerance, and insulin tolerance between WT and GLP1RKO/Y2RKO mice after RYGB.

CONCLUSIONS

Combined loss of GLP1R and Y2R-signaling was not able to negate or attenuate the beneficial effects of RYGB on body weight and glucose homeostasis in mice, suggesting that a larger number of signaling pathways is involved or that the critical pathway has not yet been identified.

A GLP-1:CCK fusion peptide harnesses the synergistic effects on metabolism of CCK-1 and GLP-1 receptor agonism in mice

Combination approaches for the treatment of metabolic diseases such as obesity and diabetes are becoming increasingly relevant. Co-administration of a glucagon-like peptide-1 receptor (GLP-1R) agonist with a cholecystokinin receptor-1 (CCKR1) agonist exert synergistic effects on weight loss in obese rodents. Here, we report on the effects of a novel fusion peptide (C2816) comprised of a stabilized GLP-1R agonist, AC3174, and a CCKR1-selective agonist, AC170222. C2816 was constructed such that AC3174 was linked to the N-terminus of AC170222, thus preserving the C-terminal amide of the CCK moiety. In functional in vitro assays C2816 retained full agonism at GLP-1R and CCKR1 at lower potency compared to parent molecules, whereas a previously reported fusion peptide in the opposite orientation, (pGlu-Gln)-CCK-8/exendin-4, exhibited no activity at either receptor. Acutely, in vivo, C2816 increased cFos in key central nuclei relevant to feeding behavior, and reduced food intake in wildtype (WT), but less so in GLP-1R-deficient (GLP-1RKO), mice. In sub-chronic studies in diet-induced obese (DIO) mice, C2816 exerted superior reduction in body weight compared to co-administration of AC3174 and AC170222 albeit at a higher molar dose. These data suggest that the synergistic pharmacological effects of GLP-1 and CCK pathways can be harnessed in a single therapeutic peptide.

Nonalcoholic steatohepatitis severity is defined by a failure in compensatory antioxidant capacity in the setting of mitochondrial dysfunction

AIM

To comprehensively evaluate mitochondrial (dys) function in preclinical models of nonalcoholic steatohepatitis (NASH).

METHODS

We utilized two readily available mouse models of nonalcoholic fatty liver disease (NAFLD) with or without progressive fibrosis: Lep^ob/Lep^ob (ob/ob) and FATZO mice on high trans-fat, high fructose and high cholesterol (AMLN) diet. Presence of NASH was assessed using immunohistochemical and pathological techniques, and gene expression profiling. Morphological features of mitochondria were assessed via transmission electron microscopy and immunofluorescence, and function was assessed by measuring oxidative capacity in primary hepatocytes, and respiratory control and proton leak in isolated mitochondria. Oxidative stress was measured by assessing activity and/or expression levels of Nrf1, Sod1, Sod2, catalase and 8-OHdG.

RESULTS

When challenged with AMLN diet for 12 wk, ob/ob and FATZO mice developed steatohepatitis in the presence of obesity and hyperinsulinemia. NASH development was associated with hepatic mitochondrial abnormalities, similar to those previously observed in humans, including mitochondrial accumulation and increased proton leak. AMLN diet also resulted in increased numbers of fragmented mitochondria in both strains of mice. Despite similar mitochondrial phenotypes, we found that ob/ob mice developed more advanced hepatic fibrosis. Activity of superoxide dismutase (SOD) was increased in ob/ob AMLN mice, whereas FATZO mice displayed increased catalase activity, irrespective of diet. Furthermore, 8-OHdG, a marker of oxidative DNA damage, was significantly increased in ob/ob AMLN mice compared to FATZO AMLN mice. Therefore, antioxidant capacity reflected as the ratio of catalase:SOD activity was similar between FATZO and C57BL6J control mice, but significantly perturbed in ob/ob mice.

CONCLUSION

Oxidative stress, and/or the capacity to compensate for increased oxidative stress, in the setting of mitochondrial dysfunction, is a key factor for development of hepatic injury and fibrosis in these mouse models.

Superior reductions in hepatic steatosis and fibrosis with co-administration of a glucagon-like peptide-1 receptor agonist and obeticholic acid in mice

OBJECTIVE

Nonalcoholic steatohepatitis (NASH) is an unmet need associated with metabolic syndrome. There are no approved therapies for NASH; however, glucagon-like peptide-1 receptor (GLP-1R) and farnesoid-X receptor (FXR) agonists are promising drug targets. We investigated the therapeutic effects of co-administration of a GLP-1R agonist, IP118, with FXR agonist obeticholic acid (OCA) in mice.

METHODS

OCA and IP118 alone and in combination were sub-chronically administered to Lep^ob/Lep^ob mice with diet-induced NASH or diet-induced obese (DIO) mice. Metabolic (body weight and glucose) and liver (biochemical and histological) endpoints were assessed. NASH severity in Lep^ob/Lep^ob mice was graded using a customized integrated scoring system.

RESULTS

OCA reduced liver weight and lipid in NASH mice (both by -17%) but had no effect on plasma ALT or AST levels. In contrast, IP118 significantly reduced liver weight (-21%), liver lipid (-15%), ALT (-29%), and AST (-27%). The combination of OCA + IP118 further reduced liver weight (-29%), liver lipid (-22%), ALT (-39%), and AST (-36%). Combination therapy was superior to monotherapies in reducing hepatic steatosis, inflammation, and fibrosis. Hepatic improvements with IP118 and OCA + IP118 were associated with reduced body weight (-4.3% and -3.5% respectively) and improved glycemic control in OCA + IP118-treated mice. In DIO mice, OCA + IP118 co-administration reduced body weight (-25.3%) to a greater degree than IP118 alone (-12.5%) and further improved glucose tolerance and reduced hepatic lipid.

CONCLUSION

Our data suggest a complementary or synergistic therapeutic effect of GLP-1R and FXR agonism in mouse models of metabolic disease and NASH.

Neurturin and a GLP-1 Analogue Act Synergistically to Alleviate Diabetes in Zucker Diabetic Fatty Rats

Neurturin (NRTN), a member of the glial-derived neurotrophic factor family, was identified from an embryonic chicken pancreatic cDNA library in a screen for secreted factors. In this study, we assessed the potential antidiabetic activities of NRTN relative to liraglutide, a glucagon-like peptide 1 receptor agonist, in Zucker diabetic fatty (ZDF) rats. Subcutaneous administration of NRTN to 8-week-old male ZDF rats prevented the development of hyperglycemia and improved metabolic parameters similar to liraglutide. NRTN treatment increased pancreatic insulin content and β-cell mass and prevented deterioration of islet organization. However, unlike liraglutide-treated rats, NRTN-mediated improvements were not associated with reduced body weight or food intake. Acute NRTN treatment did not activate c-Fos expression in key feeding behavior and metabolic centers in ZDF rat brain or directly enhance glucose-stimulated insulin secretion from pancreatic β-cells. Treating 10-week-old ZDF rats with sustained hyperglycemia with liraglutide resulted in some alleviation of hyperglycemia, whereas NRTN was not as effective despite improving plasma lipids and fasting glucose levels. Interestingly, coadministration of NRTN and liraglutide normalized hyperglycemia and other metabolic parameters, demonstrating that combining therapies with distinct mechanism(s) can alleviate advanced diabetes. This emphasizes that therapeutic combinations can be more effective to manage diabetes in individuals with uncontrolled hyperglycemia.

A lifetime aging study of human CD19 transgenic mice

Mice transgenic for human CD19 have been an important animal model to help understand the role of this molecule in B lymphocyte function. Previously, no lifetime studies had been performed to understand the effects of this CD19 over expression on the survival or spontaneous pathology within the C57BL/6J background strain. We conducted a lifetime study with interim sacrifices to understand the transgenic effects on clinical signs, body weight, survival, and spontaneous pathology. Blood and urine samples were collected from select animals at various time points during the study for measurement of clinical pathology parameters and groups of animals were euthanized and examined at predetermined intervals. There was fair survival with some animals living to 108 weeks of age. Clinical pathology evaluations revealed a declining red cell mass with a regenerative anemia, increasing total white blood cell counts and decreasing glucose level. Total protein, albumin, and globulin levels increased to 52 weeks of age and then declined to or below baseline with advancing age. Increased urinary microalbumin levels correlated with the severity of a glomerulopathy at 76 and 84 weeks of age. Mean body weight increased through 70 weeks and then declined to weights similar to week 28 at 108 weeks. Macroscopic observations included pale kidneys, enlarged seminal vesicles, and enlarged spleens (at 108 weeks of age). The most common neoplasms in this study were bronchiolar alveolar adenomas in the lung, histiocytic sarcoma in several different tissues, and hepatocellular adenomas. The most common non-neoplastic lesions were renal glomerulopathy, and pulmonary lymphocytic infiltrates with increased numbers of alveolar macrophages.

Robust anti-obesity and metabolic effects of a dual GLP-1/glucagon receptor peptide agonist in rodents and non-human primates

AIMS

To characterize the pharmacology of MEDI0382, a peptide dual agonist of glucagon-like peptide-1 (GLP-1) and glucagon receptors.

MATERIALS AND METHODS

MEDI0382 was evaluated in vitro for its ability to stimulate cAMP accumulation in cell lines expressing transfected recombinant or endogenous GLP-1 or glucagon receptors, to potentiate glucose-stimulated insulin secretion (GSIS) in pancreatic β-cell lines and stimulate hepatic glucose output (HGO) by primary hepatocytes. The ability of MEDI0382 to reduce body weight and improve energy balance (i.e. food intake and energy expenditure), as well as control blood glucose, was evaluated in mouse models of obesity and healthy cynomolgus monkeys following single and repeated daily subcutaneous administration for up to 2 months.

RESULTS

MEDI0382 potently activated rodent, cynomolgus and human GLP-1 and glucagon receptors and exhibited a fivefold bias for activation of GLP-1 receptor versus the glucagon receptor. MEDI0382 produced superior weight loss and comparable glucose lowering to the GLP-1 peptide analogue liraglutide when administered daily at comparable doses in DIO mice. The additional fat mass reduction elicited by MEDI0382 probably results from a glucagon receptor-mediated increase in energy expenditure, whereas food intake suppression results from activation of the GLP-1 receptor. Notably, the significant weight loss elicited by MEDI0382 in DIO mice was recapitulated in cynomolgus monkeys.

CONCLUSIONS

Repeated administration of MEDI0382 elicits profound weight loss in DIO mice and non-human primates, produces robust glucose control and reduces hepatic fat content and fasting insulin and glucose levels. The balance of activities at the GLP-1 and glucagon receptors is considered to be optimal for achieving weight and glucose control in overweight or obese Type 2 diabetic patients.

Abstract 271: Id3 Promotes Obesity-Induced Inflammatory Macrophage Accumulation Through Proliferation of MCP-1-Producing Adipocyte Progenitor Cells

High fat diet (HFD)-induced increases in MCP-1 are a hallmark feature of adipose tissue inflammation during obesity. Macrophages are the main producers of MCP-1 in established obesity; however, early increases in obesity-induced production of MCP-1 precede migration of M1 macrophages to adipose tissue. Global deletion of transcription factor Inhibitor of Differentiation 3 (Id3) attenuates HFD-induced obesity and adipose tissue inflammation. Specifically, Id3-/- mice have less visceral adipose tissue (VAT), fewer M1 adipose tissue macrophages, and attenuated HFD-induced MCP-1 production. The source of initial obesity-induced MCP-1 in vivo, as well as the role that Id3 plays in regulation of MCP-1, is currently unknown.

Flow cytometry demonstrated that committed CD45-CD31-Ter119-CD29+CD34+Sca-1+CD24- adipocyte progenitor cells (AdPCs) express high levels of MCP-1. HFD increased the number of AdPCs in an Id3-dependent manner. Loss of Id3 increased levels of p21Cip1 and attenuated HFD-induced proliferation of AdPCs, resulting in lower levels of MCP-1 and reduced M1 macrophage numbers in VAT, compared to Id3+/+ littermate controls. Adoptive transfer of 50,000 Id3+/+ AdPCs into Id3-/- recipient mice restored adipose tissue inflammation via increased MCP-1 levels and M1 macrophage accumulation in VAT. Notably, the M1:M2 macrophage ratio significantly increased due to injection of AdPCs. Additionally, flow cytometry identified MCP-1-producing CD45-CD31-CD34+CD44+CD90+ AdPCs in human omental and subcutaneous adipose tissue. The percentage of AdPCs expressing MCP-1 was higher in omental adipose compared to subcutaneous adipose. Furthermore, high surface expression of CD44 marked abundant MCP-1 producers, only in omental adipose tissue.

The present study provides the first in vivo evidence that committed AdPCs are the source of early obesity-induced MCP-1. Id3 is a critical regulator of p21Cip1 expression and proliferation in AdPCs, and in this manner, promotes overall MCP-1 expression and M1 macrophage accumulation in VAT. Inhibition of Id3 and AdPC expansion, as well as CD44 expression in human AdPCs, may serve as unique therapeutic targets for the regulation of adipose tissue inflammation.

Abstract 15: The Helix-Loop-Helix Factor Id3 Links Natural Helper Cells to Proliferation of Atheroprotective B-1a Cells

Natural immunity is emerging as important for atheroprotection. Natural IgM antibodies, such as E06, that recognize oxidative epitopes on LDL or phospholipids prevent atherosclerosis and are produced by the atheroprotective B cell subset, the B-1a B cell. IL5, an important B-1a B cell mitogen, can be produced by the innate lymphoid cell, the natural helper (NH) cell. We previously demonstrated that splenic B cells provide atheroprotection to B cell deficient mice, an effect dependent on the helix-loop-helix transcription factor, Id3. Taken together, these results raise the hypothesis that Id3 may be an important regulator of splenic B-1a B cells and natural immunity in atheroprotection.

Methods and Results

Id3 -/- Apoe -/- mice at 8 weeks old had fewer B-1a cells in the spleen (200672 ±58019, n = 9) compared to Id3 +/+ Apoe -/- mice (511840 ±88811, n = 9) as determined by flow cytometry. Consistent with fewer B-1a B cells, there were lower levels of serum E06 in Id3 -/- Apoe -/- mice compared to Id3 +/+ Apoe -/- mice (1573 ±300 RLU vs. 2807 ±263 RLU respectively, n = 8 for each group) as assessed by ELISA. Id3 -/- Apoe -/- mice had decreased B-1a B cell homeostatic proliferation compared to Id3 +/+ Apoe -/- mice (30.0 ±3.3% vs. 54.4 ± 1.2% respectively, n = 4) as measured by in situ CFSE. However, B-1a B cell proliferation and number and levels of E06 were unchanged in mice with B cell specific deletion of Id3 compared to controls. To determine if Id3 is required for IL33 induced levels of IL5, IL33 or vehicle control was i.p. injected into Id3 +/+ Apoe -/- mice or Id3 -/- Apoe -/- mice every 3 days for 7 days. Id3 -/- Apoe -/- mice had less IL33 induced serum IL5 levels (5.1 ±3.1 pg mL -1 , n = 5) compared to Id3 +/+ Apoe -/- mice (67.4 ±22.9 pg mL -1 , n = 4). Indeed, loss of Id3 significantly attenuated IL33 induced IL5 production in NH cells measured by flow cytometric intracellular cytokine staining ( Id3 -/- Apoe -/- : 31.1 ±5.4%, n = 6 vs. Id3 +/+ Apoe -/- : 50.3 ±4.3%, n = 6). NH cells are also present and can to produce IL5 in response to exogenous IL33 (vehicle: 4.0 ±1.4%, n = 4 vs. IL33: 14.7 ±2.4%, n = 4) in the aortic adventitia/perivascular adipose tissue of Apoe -/- mice.

Conclusion

Results provide the first evidence implicating Id3 as a key regulator of NH cell IL5 production and B-1a B cell proliferation.

Drosophila: a model for understanding obesity and diabetic complications

The molecular mechanisms underlying development of obesity and diabetic complications are not well understood. Drosophila has become a popular model organism for studying a variety of human diseases. We discuss here emerging Drosophila models of obesity and diabetic complications.

Extension of life-span by loss of CHICO, a Drosophila insulin receptor substrate protein

The Drosophila melanogaster gene chico encodes an insulin receptor substrate that functions in an insulin/insulin-like growth factor (IGF) signaling pathway. In the nematode Caenorhabditis elegans, insulin/IGF signaling regulates adult longevity. We found that mutation of chico extends fruit fly median life-span by up to 48% in homozygotes and 36% in heterozygotes. Extension of life-span was not a result of impaired oogenesis in chico females, nor was it consistently correlated with increased stress resistance. The dwarf phenotype of chico homozygotes was also unnecessary for extension of life-span. The role of insulin/IGF signaling in regulating animal aging is therefore evolutionarily conserved.

Genetic and biochemical characterization of dTOR, the Drosophila homolog of the target of rapamycin

The adaptation of growth in response to nutritional changes is essential for the proper development of all organisms. Here we describe the identification of the Drosophila homolog of the target of rapamycin (TOR), a candidate effector for nutritional sensing. Genetic and biochemical analyses indicate that dTOR impinges on the insulin signaling pathway by autonomously affecting growth through modulating the activity of dS6K. However, in contrast to other components in the insulin signaling pathway, partial loss of dTOR function preferentially reduces growth of the endoreplicating tissues. These results are consistent with dTOR residing on a parallel amino acid sensing pathway.

Genetic control of size in Drosophila

During the past ten years, significant progress has been made in understanding the basic mechanisms of the development of multicellular organisms. Genetic analysis of the development of Caenorhabditis elegans and Drosophila has unearthed a fruitful number of genes involved in establishing the basic body plan, patterning of limbs, specification of cell fate and regulation of programmed cell death. The genes involved in these developmental processes have been conserved throughout evolution and homologous genes are involved in the patterning of insect and human limbs. Despite these important discoveries, we have learned astonishingly little about one of the most obvious distinctions between animals: their difference in body size. The mass of the smallest mammal, the bumble-bee bat, is 2 g while that of the largest mammal, the blue whale, is 150 t or 150 million grams. Remarkably, even though they are in the same class, body size can vary up to 75-million-fold. Furthermore, this body growth can be finite in the case of most vertebrates or it can occur continuously throughout life, as for trees, molluscs and large crustaceans. Currently, we know comparatively little about the genetic control of body size. In this article we will review recent evidence from vertebrates and particularly from Drosophila that implicates insulin/insulin-like growth factor-I and other growth pathways in the control of cell, organ and body size.

Autonomous control of cell and organ size by CHICO, a Drosophila homolog of vertebrate IRS1-4

The control of growth is fundamental to the developing metazoan. Here, we show that CHICO, a Drosophila homolog of vertebrate IRS1-4, plays an essential role in the control of cell size and growth. Animals mutant for chico are less than half the size of wild-type flies, owing to fewer and smaller cells. In mosaic animals, chico homozygous cells grow slower than their heterozygous siblings, show an autonomous reduction in cell size, and form organs of reduced size. Although chico flies are smaller, they show an almost 2-fold increase in lipid levels. The similarities of the growth defects caused by mutations in chico and the insulin receptor gene in Drosophila and by perturbations of the insulin/IGF1 signaling pathway in vertebrates suggest that this pathway plays a conserved role in the regulation of overall growth by controling cell size, cell number, and metabolism.

Isomazole disposition in man as a function of dose and route of administration

The disposition of a new cardiotonic agent (isomazole (ISO] was evaluated in healthy volunteers after various single oral (p.o.), intravenous (i.v.), and multiple p.o. doses. Blood samples were collected after dosing in all studies, with urine collected in the single i.v. and multiple dose studies. All biological samples were measured for ISO. In the multiple dose study, samples were collected for analysis after the first and last doses administered. In addition to ISO, several known metabolites (hydroxyisomazole (OHISO), sulfone (SULF), and hydroxysulfone (OHSULF) analogs) were measured after the first and last doses given in the multiple dose study. Pharmacokinetic values compared between doses suggested no saturable processes existed over the entire dose range. The single i.v. dose data showed ISO experienced some extravascular distribution (mean V beta = 1.82 l kg-1), with a high clearance (mean Cls = 18.8 ml min-1 kg-1) and a short half-life (mean t 1/2 = 1.1 h). Elimination was primarily nonrenal (Clr = 3.5 ml min-1 kg-1). Single p.o. data supported these findings and further suggested rapid absorption. ISO data from the first dose of the multiple dose study was in agreement with these data; however, the last dose showed a higher Cls (33.0 ml min-1 kg-1) (p = 0.055). Although not statistically significant, metabolite plasma data and and urinary excretion patterns changed. An increase was observed in plasma AUC and metabolite excretion of SULF and OHSULF, while a decrease was observed in the same parameters for OHISO. These results suggest that multiple dosing of ISO produces autoinduction of ISO metabolism through selective metabolic routes.

14C-isomazole disposition in man after oral administration

A 50-mg dose containing 50 microCi 14C-isomazole was administered orally to five healthy male volunteers. Blood, plasma, urine, feces, and saliva were collected and measured for total 14C; in addition, all collections except feces were measured for parent drug (ISO) and three metabolites: hydroxyisomazole (OHISO) and sulfone (SULF) and hydroxysulfone (OHSULF) analogues. Urine and fecal recoveries accounted for 97.0% of the drug administered, with 62.6% excreted in urine and 32.4% in feces. Only 47% of the drug recovered in urine could be identified, with ISO the largest constituent. Total plasma 14C peaked at 1.5 hr, indicating rapid absorption, and produced a mean half-life of 3.7 hr. This was similar to the total 14C half-life found in blood (3.1 hr) but longer than in red blood cells (1.8 hr) or saliva (1.4 hr), suggesting that different ISO-related compounds contributed to the results found in each fluid or tissue. An unidentified metabolite(s) composed a large portion of circulating plasma 14C and produced the longer half-life encountered in plasma. ISO exhibited a short half-life (1.35 hr), a high oral clearance (Cls/F; 24.2 ml/min/kg), and some extravascular distribution (V beta; 3.07 L/kg). Total 14C in red blood cells and saliva related very well to plasma ISO disposition, suggesting preferential distribution of parent drug across cellular membranes. The estimated RBC:plasma ISO ratio (1.79) confirmed this hypothesis. Saliva may be used as a noninvasive means to monitor ISO disposition.

Pharmacologic effects in man of a specific serotonin-reuptake inhibitor

Fluoxetine (Li-ly 110140) caused a 63 percent inhibition of [3H]serotonin uptake into platelets obtained from normal volunteers to whom the drug was administered daily for 7 days. This dose had no effect on the usual pressor response produced by injections of norepinephrine or tyramine.