Metastatic pathways and time courses in the orderly progression of cutaneous melanoma

BACKGROUND

It is known that two-thirds of patients who develop clinical metastases following treatment of a primary cutaneous melanoma initially present with locoregional metastases and one-third initially present with distant metastases. However, few reports in the literature give detailed figures on different metastatic pathways in cutaneous melanoma.

OBJECTIVES

The aim of the present study was to perform a detailed analysis of the different metastatic pathways, the time course of the development of metastases and the factors influencing them.

METHODS

In a series of 3001 patients with primary cutaneous melanoma at first presentation, 466 subsequently developed metastasis and were followed-up over the long term at the University of Tuebingen, Germany between 1976 and 1996. Different pathways of metastatic spread were traced. Associated risk factors for the different pathways were assessed. Differences in survival probabilities were calculated by the Kaplan-Meier method and evaluated by the log-rank test.

RESULTS

In 50.2% of the patients the first metastasis after treatment of the primary tumour developed in the regional lymph nodes. In the remaining half of the patient sample the first metastasis developed in the lymphatic drainage area in front of the regional lymph nodes, as satellite or in-transit metastases (21.7%) or as direct distant metastases (28.1%). Anatomical location, sex and tumour thickness were significant risk factors for the development of metastasis by different pathways. The most important risk factor appeared to be the location of the primary tumour. The median intervals elapsing before the first metastasis differed significantly between the different metastatic pathways. The direct distant metastases became manifest after a median period of 25 months, thus later than the direct regional lymph node metastases (median latency period, 16 months) and the direct satellite and in-transit metastases (median latency period, 17 months). In patients who developed distant metastases the period of development was independent of the metastatic route. The time at which the distant metastases developed was roughly the same (between 24 and 30 months after the detection of the primary tumour), irrespective of whether satellite or in-transit metastases, lymph node metastases or distant metastases were the first to occur.

CONCLUSIONS

The time course of the development of distant metastasis was more or less the same irrespective of the metastatic pathway; this suggests that in patients with in-transit or satellite metastasis or regional lymph node metastasis, haematogenic metastatic spread had already taken place. Thus, the diagnostic value of sentinel lymph node biopsy and the therapeutic benefit of elective lymph node dissection may be limited, as satellite and in-transit metastases or direct distant metastases will not be detected and haematogenous spread may already have taken place when the intervention is performed.

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.

Molecular activation of PPARγ by angiotensin II type 1-receptor antagonists

OBJECTIVE AND DESIGN

Elevated blood pressure and insulin resistance are strongly associated in patients. We explored the potential for the anti-hypertensive angiotensin II type 1-receptor (ATR(1)) antagonists to improve insulin sensitivity through modulation of the nuclear receptor PPARgamma, in vitro and in vivo compared to the potent insulin sensitizer, rosiglitazone.

METHODS

PPARgamma modulation by ATR(1) antagonists was measured first by direct recruitment of PGC-1, followed by trans-activation reporter assays in cells, and promotion of adipogenesis in fibroblast and pre-adipocyte cell lines. Improvement of insulin sensitivity was measured as changes in levels of glucose, insulin, and adiponectin in ob/ob mice.

RESULTS

Telmisartan, candesartan, irbesartan, and losartan (but not valsartan or olmesartan) each served as bona fide PPARgamma ligands in vitro, with EC(50) values between 3 and 5 micro mol/l. However, only telmisartan, and to a lesser extent candesartan, resulted in significant PPARgamma agonism in cells. In vivo, although rosiglitazone significantly lowered both glucose (33%, p<0.01) and insulin (61%, p<0.01) levels and increased expression of adiponectin (74%, p<0.001), sartan treatment had no effect.

CONCLUSIONS

Many members of the sartan family of ATR(1) antagonists are PPARgamma ligands in cell-free assays but their modulation of PPARgamma in cells is relatively weak. Furthermore, none appear to improve insulin sensitivity in a rodent model under conditions where other insulin sensitizers, including rosiglitazone, do. These results question whether reported effects of sartans on insulin sensitivity may be through other means, and should guide further efforts to develop dual agents to treat hypertension and insulin resistance.

Long phase coherence time and number squeezing of two Bose-Einstein condensates on an atom chip

We measure the relative phase of two Bose-Einstein condensates confined in a radio frequency induced double-well potential on an atom chip. We observe phase coherence between the separated condensates for times up to approximately 200 ms after splitting, a factor of 10 longer than the phase diffusion time expected for a coherent state for our experimental conditions. The enhanced coherence time is attributed to number squeezing of the initial state by a factor of 10. In addition, we demonstrate a rotationally sensitive (Sagnac) geometry for a guided atom interferometer by propagating the split condensates.

Corroles with group 15 ions. 2. Synthesis and characterization of octaethylcorroles containing a phosphorus central atom

The synthesis, spectroscopic characterization, and electrochemistry of five new phosphorus corroles are reported. The investigated complexes contain alkyl, aryl, oxo, or hydrido axial ligands and are represented as (OEC)P(H)2, (OEC)P(CH3)2, (OEC)P(C6H5)2, (OEC)P=O, and [(OEC)P(CH3)]+ClO4-, where OEC is the trianion of octaethylcorrole. The products of electrooxidation and/or electroreduction were also characterized by UV-vis and ESR spectroscopy. Correlations are shown to exist between reversible half-wave potentials for the first oxidation and first reduction of each compound and the combined electronegativity of the central ion and the axial ligand(s). The electrochemical HOMO-LUMO gap, defined as the difference between first reduction and first oxidation, was found to be independent of the electron-transfer site and similar in magnitude to the value generally observed for metalloporphyrins with planar macrocycles, i.e., 2.25 +/- 0.15 V.

Disruption of G protein-coupled receptor 39 impairs insulin secretion in vivo

GPR39 is a G protein-coupled receptor expressed in liver, gastrointestinal tract, adipose tissue, and pancreas. We have recently shown that young GPR39(-/-) mice have normal body weight, food intake, and fasting glucose and insulin levels. In this study, we examined the role of GPR39 in aging and diet-induced obese mice. Body weight and food intake were similar in wild-type and GPR39(-/-) mice as they aged from 12 to 52 wk or when fed a low-fat/high-sucrose or high-fat/high-sucrose diet. Fifty-two-week-old GPR39(-/-) mice showed a trend toward decreased insulin levels after oral glucose challenge. When fed either a low-fat/high-sucrose or high-fat/high-sucrose diet, GPR39(-/-) mice had increased fed glucose levels and showed decreased serum insulin levels during an oral glucose tolerance test in the face of unchanged insulin tolerance. Pancreas morphology and glucose-stimulated insulin secretion in isolated islets from wild-type and GPR39(-/-) mice were comparable, suggesting that GPR39 is not required for pancreas development or ex vivo insulin secretion. Small interfering RNA-mediated knockdown of GPR39 in clonal NIT-1 beta-cells revealed that GPR39 regulates the expression of insulin receptor substrate-2 and pancreatic and duodenal homeobox-1 in a cell-autonomous manner; insulin receptor substrate-2 mRNA was also significantly decreased in the pancreas of GPR39(-/-) mice. Taken together, our data indicate that GPR39 is required for the increased insulin secretion in vivo under conditions of increased demand, i.e. on development of age-dependent and diet-induced insulin resistance. Thus, GPR39 agonists may have potential for the treatment of type 2 diabetes.

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.

Corroles with group 15 metal ions. Synthesis and characterization of octaethylcorroles containing As, Sb, and Bi ions in +3, +4, and oxidation states

The synthesis, spectroscopic characterization, and electrochemistry of As, Sb, and Bi corroles are reported. The investigated complexes are represented by [(OEC)AsV(CH3)]+ClO4- and (OEC)M where M = As(III), Sb(III), or Bi(III) and OEC is the trianion of octaethylcorrole. The products of each redox reaction are characterized by UV-vis and ESR spectroscopy. The first one-electron oxidations of (OEC)As and (OEC)Sb are metal-centered and result in the formation of [(OEC)AsIV]+ and [(OEC)SbIV]+. A second one-electron oxidations generates [(OEC)AsV]2+ and [(OEC.)SbIV]2+, the latter of which is slowly converted to a Sb(V) corrole, [(OEC)SbV]2+. The first one-electron oxidation of (OEC)Bi leads only to the Bi(III) pi-cation radical, but a second one-electron oxidation is proposed to give a Bi(IV) complex, [(OEC)Bi]2+. The first reduction of [(OEC)AsV(CH3)]+ClO4- is accompanied by loss of the sigma-bonded methyl ligand and formation of an As(III) complex.

Development of an orally delivered GLP-1 receptor agonist through peptide engineering and drug delivery to treat chronic disease

Peptide therapeutics are increasingly used in the treatment of disease, but their administration by injection reduces patient compliance and convenience, especially for chronic diseases. Thus, oral administration of a peptide therapeutic represents a significant advance in medicine, but is challenged by gastrointestinal instability and ineffective uptake into the circulation. Here, we have used glucagon-like peptide-1 (GLP-1) as a model peptide therapeutic for treating obesity-linked type 2 diabetes, a common chronic disease. We describe a comprehensive multidisciplinary approach leading to the development of MEDI7219, a GLP-1 receptor agonist (GLP-1RA) specifically engineered for oral delivery. Sites of protease/peptidase vulnerabilities in GLP-1 were removed by amino acid substitution and the peptide backbone was bis-lipidated to promote MEDI7219 reversible plasma protein binding without affecting potency. A combination of sodium chenodeoxycholate and propyl gallate was used to enhance bioavailability of MEDI7219 at the site of maximal gastrointestinal absorption, targeted by enteric-coated tablets. This synergistic approach resulted in MEDI7219 bioavailability of ~ 6% in dogs receiving oral tablets. In a dog model of obesity and insulin resistance, MEDI7219 oral tablets significantly decreased food intake, body weight and glucose excursions, validating the approach. This novel approach to the development of MEDI7219 provides a template for the development of other oral peptide therapeutics.

Physicochemical studies of the d(G3T4G3)*d(G3A4G3).d(C3T4C3) triple helix

We have targeted the d(G3A4G3).d(C3T4C3) duplex for triplex formation with d(G3T4G3) in the presence of MgCl2. The resulting triple helix, d(G3T4G3)*d(G3-A4G3).d(C3T4C3), is considerably weaker than the related triplex, d(G3A4G3)*d(G3A4G3).d(C3T4C3), and melts in a biphasic manner, with the third strand dissociating at temperatures about 20-30 degrees C below that of the remaining duplex. This is in distinct contrast to the d(G3A4G3)*d(G3A4G3).d(C3T4C3) triplex, which melts in essentially a single transition. Gel electrophoresis under non-denaturing conditions shows the presence of the d(G3T4G3)*d(G3A4G3).d(C3T4C3) triplex as a band of low mobility compared to the duplex or the single strand bands. Binding of the d(G3T4G3) third strand and the purine strand of the duplex can be monitored by imino proton NMR spectra. While these spectra are typically very broad for intermolecular triplexes, the line widths can be dramatically narrowed by the addition of two thymines to both ends of the pyrimidine strand. Thermodynamic analysis of UV melting curves shows that this triplex is considerably less stable than related triplexes formed with the same duplex. The orientation of the third strand was addressed by a combination of fluorescence energy transfer and UV melting experiments. Results from these experiments suggest that, in the unlabeled triplex, the preferred orientation of the third strand is parallel to the purine strand of the duplex.

Application of constraint programming techniques for structure prediction of lattice proteins with extended alphabets

MOTIVATION

Predicting the ground state of biopolymers is a notoriously hard problem in biocomputing. Model systems, such as lattice proteins, are simple tools and valuable to test and improve new methods. Best known are models with sequences composed from a binary (hydrophobic and polar) alphabet. The major drawback is the degeneracy, i.e. the number of different ground state conformations.

RESULTS

We show how recently developed constraint programming techniques can be used to solve the structure prediction problem efficiently for a higher order alphabet. To our knowledge it is the first report of an exact and computationally feasible solution to model proteins of length up to 36 and without resorting to maximally compact states. We further show that degeneracy is reduced by more than one order of magnitude and that ground state conformations are not necessarily compact. Therefore, more realistic protein simulations become feasible with our model.

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.

Identification of invasive fungal diseases in immunocompromised patients by combining an Aspergillus specific PCR with a multifungal DNA-microarray from primary clinical samples

The increasing incidence of invasive fungal diseases (IFD), most of all invasive aspergillosis (IA) in immunocompromised patients emphasises the need to improve the diagnostic tools for detection of fungal pathogens. We investigated the diagnostic performance of a multifungal DNA-microarray detecting 15 different fungi [Aspergillus, Candida, Fusarium, Mucor, Rhizopus, Scedosporium and Trichosporon species (spp.)] in addition to an Aspergillus specific polymerase chain reaction (PCR) assay. Biopsies, bronchoalveolar lavage and peripheral blood samples of 133 immunocompromised patients (pts) were investigated by a multifungal DNA-microarray as well as a nested Aspergillus specific PCR assay. Patients had proven (n = 18), probable (n = 29), possible (n = 48) and no IFD (n = 38) and were mostly under antifungal therapy at the time of sampling. The results were compared to culture, histopathology, imaging and serology, respectively. For the non-Aspergillus IFD the microarray analysis yielded in all samples a sensitivity of 64% and a specificity of 80%. Best results for the detection of all IFD were achieved by combining DNA-microarray and Aspergillus specific PCR in biopsy samples (sensitivity 79%; specificity 71%). The molecular assays in combination identify genomic DNA of fungal pathogens and may improve identification of causative pathogens of IFD and help overcoming the diagnostic uncertainty of culture and/or histopathology findings, even during antifungal therapy.

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.

Targeted mutations induced by a single acetylaminofluorene DNA adduct in mammalian cells and bacteria

Mutagenic specificity of 2-acetylaminofluorene (AAF) has been established in mammalian cells and several strains of bacteria by using a shuttle plasmid vector containing a single N-(deoxyguanosin-8-yl)acetylaminofluorene (C8-dG-AAF) adduct. The nucleotide sequence of the gene conferring tetracycline resistance was modified by conservative codon replacement so as to accommodate the sequence d(CCTTCGCTAC) flanked by two restriction sites, Bsm I and Xho I. The corresponding synthetic oligodeoxynucleotide underwent reaction with 2-(N-acetoxy-N-acetylamino)-fluorene (AAAF), forming a single dG-AAF adduct. This modified oligodeoxynucleotide was hybridized to its complementary strand and ligated between the Bsm I and Xho I sites of the vector. Plasmids containing the C8-dG-AAF adduct were used to transfect simian virus 40-transformed simian kidney (COS-1) cells and to transform several AB strains of Escherichia coli. Colonies containing mutant plasmids were detected by hybridization to 32P-labeled oligodeoxynucleotides. Presence of the single DNA adduct increased the mutation frequency by 8-fold in both COS cells and E. coli. Over 80% of mutations detected in both systems were targeted and represented G.C----C.G or G.C----T.A transversions or single nucleotide deletions. We conclude that modification of a deoxyguanosine residue with AAF preferentially induces mutations targeted at this site when a plasmid containing a single C8-dG-AAF adduct is introduced into mammalian cells or bacteria.

Evidence for the dominance of direct excitation of DNA in the formation of strand breaks in cells following irradiation

The yields of radiation-induced strand breaks measured in a plasmid DNA irradiated as a 'dry film' are similar to those measured in SV40 DNA irradiated in a cellular environment (Roots et al. 1985). This suggests a common mechanism, namely direct excitation of the DNA rather than indirectly inflicted damage from radiation-induced water radicals. This result is discussed in terms of a recently proposed mechanism of excitation transfer in DNA following direct excitation by ionizing radiation.

Activation of TrkB with TAM-163 results in opposite effects on body weight in rodents and non-human primates

Strong genetic data link the Tyrosine kinase receptor B (TrkB) and its major endogenous ligand brain-derived neurotrophic factor (BDNF) to the regulation of energy homeostasis, with loss-of-function mutations in either gene causing severe obesity in both mice and humans. It has previously been reported that peripheral administration of the endogenous TrkB agonist ligand neurotrophin-4 (NT-4) profoundly decreases food intake and body weight in rodents, while paradoxically increasing these same parameters in monkeys. We generated a humanized TrkB agonist antibody, TAM-163, and characterized its therapeutic potential in several models of type 2 diabetes and obesity. In vitro, TAM-163 bound to human and rodent TrkB with high affinity, activated all aspects of the TrkB signaling cascade and induced TrkB internalization and degradation in a manner similar to BDNF. In vivo, peripheral administration of TAM-163 decreased food intake and/or body weight in mice, rats, hamsters, and dogs, but increased food intake and body weight in monkeys. The magnitude of weight change was similar in rodents and non-human primates, occurred at doses where there was no appreciable penetration into deep structures of the brain, and could not be explained by differences in exposures between species. Rather, peripherally administered TAM-163 localized to areas in the hypothalamus and the brain stem located outside the blood-brain barrier in a similar manner between rodents and non-human primates, suggesting differences in neuroanatomy across species. Our data demonstrate that a TrkB agonist antibody, administered peripherally, causes species-dependent effects on body weight similar to the endogenous TrkB ligand NT-4. The possible clinical utility of TrkB agonism in treating weight regulatory disorder, such as obesity or cachexia, will require evaluation in man.

Performance characteristics of soot primary particle size measurements by time-resolved laser-induced incandescence

A detailed analysis of various factors that influence the accuracy of time-resolved laser-induced incandescence for the determination of primary soot particles is given. As the technique relies on the measurement of the signal ratio at two detection times of the enhanced thermal radiation after an intense laser pulse, guidelines are presented for a suitable choice of detection times to minimize statistical uncertainty. An error analysis is presented for the issues of laser energy absorption, vaporization, heat conduction, and signal detection. Results are shown for a laminar ethene diffusion flame that demonstrate that concurring results are obtained for various laser irradiances, detection characteristics, and times of observation.

Prodrug delivery of novel PTP1B inhibitors to enhance insulin signalling

A growing percentage of the population is resistant to two key hormones - insulin and leptin - as a result of increased obesity, often leading to significant health consequences such as type 2 diabetes. Protein tyrosine phosphatase 1B (PTP1B) is a key negative regulator of signalling by both of these hormones, so that inhibitors of this enzyme may provide promise for correcting endocrine abnormalities in both diabetes and obesity. As with other tyrosine phosphatases, identification of viable drug candidates targeting PTP1B has been elusive because of the nature of its active site. Beginning with novel phosphotyrosine mimetics, we have designed some of the most potent PTP1B inhibitors. However, their highly acidic structures limit intrinsic permeability and pharmacokinetics. Ester prodrugs of these inhibitors improve their drug-like properties with the goal of delivering these nanomolar inhibitors to the cytoplasm of cells within target tissues. In addition to identifying prodrugs that is able to deliver active drugs into cells to inhibit PTP1B and increase insulin signalling, these compounds were further modified to gain a variety of cleavage properties for targeting activity in vivo. One such prodrug candidate improved insulin sensitivity in ob/ob mice, with lowered fasting blood glucose levels seen in the context of lowered fasting insulin levels following 4 days of intraperitoneal dosing. The results presented in this study highlight the potential for design of orally active drug candidates targeting PTP1B, while also delineating the considerable challenges remaining.