Biomedical subjects

S Rossner

Publications and source records attributed to S Rossner.

At least 19 recordsLinked to original sources

PubMed2006

Cetilistat (ATL-962), a novel lipase inhibitor: a 12-week randomized, placebo-controlled study of weight reduction in obese patients.

OBJECTIVE: To determine the efficacy, safety and tolerability of cetilistat (ATL-962), a novel inhibitor of gastrointestinal (GI) lipases, in obese patients. DESIGN: Phase II, multicentre, randomized, placebo-controlled, parallel group study. Enrolled patients (N=442) were advised a hypocaloric diet (deficient by 500 kcal per day, 30% of calories from fat) for a 2-week run-in period. Patients who satisfied the entry criteria (N=371) continued on the hypocaloric diet and were randomized to either placebo or one of three different doses of cetilistat (60 mg three times daily t.i.d., 120 mg t.i.d. and 240 mg t.i.d.) for 12 weeks, followed by a 4-week post-treatment follow-up. Safety, tolerability and body weight were assessed, together with other parameters associated with obesity. OUTCOME MEASURES: The primary outcome measure was absolute change in body weight from baseline. Secondary outcomes included the proportion of patients achieving pre-defined weight loss targets, changes from baseline in waist circumference and in blood lipids. GI tolerability criteria were specifically assessed, as was safety. RESULTS: Treatment with cetilistat reduced mean body weight to similar extents at all doses, which were statistically significant compared with placebo (60 mg t.i.d. 3.3 kg, P<0.03; 120 mg t.i.d. 3.5 kg, P=0.02; 240 mg t.i.d. 4.1 kg, P<0.001). Total serum and low-density lipoprotein cholesterol levels were likewise significantly reduced by 3-11% at all doses of cetilistat. Cetilistat was well tolerated. The frequency of withdrawal owing to treatment-emergent adverse events was similar between cetilistat-treated groups (5.3-7.6%) and placebo (7.6%). Adverse events were generally mild to moderate in intensity, occurred on only one occasion and were mostly GI in nature. The incidence of GI adverse events was increased in the cetilistat-treated groups compared to placebo. However, those GI adverse events, such as flatus with discharge and oily spotting, only occurred in 1.8-2.8% of subjects in the cetilistat-treated groups. CONCLUSIONS: Cetilistat produced a clinically and statistically significant weight loss in obese patients in this short-term 12-week study. This was accompanied by significant improvements in other obesity-related parameters. Cetilistat treatment was well tolerated. The risk-benefit demonstrated in this study in terms of weight loss vs intolerable GI adverse effects shows that cetilistat merits further evaluation for the pharmacotherapy of obesity and related disorders.

Adult↗

PubMed2005

BMI, waist-circumference and waist-hip-ratio as diagnostic tests for fatness in adolescents.

OBJECTIVE: To evaluate the diagnostic accuracy of body mass index (BMI, kg/m(2)), waist-circumference (WC) and waist-hip-ratio (WHR) as diagnostic tests for detecting fatness in adolescents. DESIGN: A cross-sectional analysis of 474 healthy adolescents aged 17 y was used. Measurements of height, weight, WC, hip-circumference and body fat percentage (%BF) were obtained. The diagnostic accuracy for detecting excess fatness was evaluated through receiver operating characteristics (ROC) analyses with %BF, measured by densitometry (air-displacement plethysmography), as reference test. RESULTS: BMI and WC showed strong positive correlation (r=0.68-0.73; P<0.0001) with %BF in both sexes, but the correlation was weaker for WHR (r=0.30-0.41; P<0.0001). For overweight and obesity in boys and obesity in girls, the area under the ROC curve was high (0.96-0.99) for BMI and WC. WHR was not significantly better than chance as diagnostic test for obesity in girls. For BMI and WC, highly sensitive and specific cutoffs for obesity could be derived, while larger trade-offs were needed for detecting overweight in girls. The cutoffs producing equal sensitivity and specificity were lower than the ones minimizing the absolute number of misclassifications. The latter approached internationally recommended reference values, but were still several units lower for BMI in girls and several centimeters lower for WC in boys. CONCLUSION: BMI and WC were found to perform well as diagnostic tests for fatness, while WHR was less useful. The discrepancies between cutoffs producing equal sensitivity and specificity, cutoffs minimizing the absolute number of misclassifications and internationally recommended reference values for overweight and obesity highlight the importance of specifying the characteristics of classification systems for different settings.

Adipose Tissue↗

PubMed2003

Dusting off the epidemiological triad: could it work with obesity?

The search for effective ways of dealing with obesity has centred on biological research and clinical management. However, obesity needs to be conceptualized more broadly if the modern pandemic is to be arrested. The epidemiological triad (hosts, agent/vectors and environments) has served us well in dealing with epidemics in the past, and may be worth re-evaluating to this end. Education, behaviour change and clinical practices deal predominantly with the host, although multidisciplinary practices such as shared-care might also be expected to impact on other corners of the triad. Technology deals best with the agent of obesity (energy imbalance) and it's vectors (excessive energy intake and/or inadequate energy expenditure), and policy and social change are needed to cope with the environment. The value of a broad model like this, rather than specific isolated approaches, is that the key players such as legislators, health professionals, governments and industry can see their roles in attenuating and eventually reversing the epidemic. It also highlights the need to intervene at all levels in obesity control and reduces the relevance of arguments about nature vs. nurture.

Dietary Fats↗

PubMed2002

Expression of beta-Secretase mRNA in the brain of rats with immunohistochemical destruction of basal forebrain cholinergic system.

We studied properties of cloned BACE mRNA (beta-site of the enzyme cleaving amyloid precursor protein) and evaluated the possibility of using this clone for identification and/or prediction of neurodegenerative disorders associated with cholinergic deficiency. Wistar rats subjected to immunohistochemical destruction of the basal forebrain cholinergic system were used as the experimental model. Nonradioactive in situ hybridization and immunohistochemical visualization of the astroglia revealed strong hybridization signal of BACE mRNA in neurons of the cortex, hippocampus, and thalamus. Astrocytes remained unstained. Immunohistochemical destruction of the basal forebrain produced no significant changes in the distribution of BACE mRNA.

Amyloid Precursor Protein Secretases↗

PubMed2001

Neuronal and glial beta-secretase (BACE) protein expression in transgenic Tg2576 mice with amyloid plaque pathology.

We measured tissue distribution and expression pattern of the beta-site amyloid precursor protein (APP)-cleaving enzyme (BACE) in the brains of transgenic Tg2576 mice that show amyloid pathology. BACE protein was expressed at high levels in brain; at lower levels in heart and liver; and at very low levels in pancreas, kidney, and thymus and was almost absent in spleen and lung when assayed by Western blot analysis. We observed strictly neuronal expression of BACE protein in the brains of nontransgenic control mice, with the most robust immunocytochemical labeling present in the cerebral cortex, hippocampal formation, thalamus, and cholinergic basal forebrain nuclei. BACE protein levels did not differ significantly between control and transgenic mice or as a result of aging. However, in the aged, 17-month-old Tg2576 mice there was robust amyloid plaque formation, and BACE protein was also present in reactive astrocytes present near amyloid plaques, as shown by double immunofluorescent labeling and confocal laser scanning microscopy. The lack of astrocytic BACE immunoreactivity in young transgenic Tg2576 mice suggests that it is not the APP overexpression but rather the amyloid plaque formation that stimulates astrocytic BACE expression in Tg2576 mice. Our data also suggest that the neuronal overexpression of APP does not induce the overexpression of its metabolizing enzyme in neurons. Alternatively, the age-dependent accumulation of amyloid plaques in the Tg2576 mice does not require increased neuronal expression of BACE. Our data support the hypothesis that neurons are the primary source of beta-amyloid peptides in brain and that astrocytic beta-amyloid generation may contribute to amyloid plaque formation at later stages or under conditions when astrocytes are activated.

Alzheimer Disease↗

PubMed2001

Developmentally induced microencephalopathy in guinea pigs--embryonic glial cell activation marks selective neuronal death.

We have recently shown that in utero treatment of guinea pigs with the DNA methylating substance methylazoxymethanol acetate (MAM) on gestation day (GD) 24 results in neocortical microencephalopathy, increased protein kinase C activity and altered processing of the amyloid precursor protein in neocortex of the offsprings. In order to identify the primary neuronal lesions produced by MAM-treatment, we mapped the 5-bromo-2'-deoxyuridine (BrdU)-incorporation in dividing neurons on GD 24 and we followed the effects of MAM-treatment on GD 24 on embryonic immediate early gene expression and on glial cell activation. BrdU injected on GD 24 labeled many neurons of the ventricular zone and of the intermediate zone but only scattered neurons of the cortical plate. When time-mated guinea pigs were injected intraperitoneally with MAM on GD 24, we observed the activation of microglial cells in the ventricular/intermediate zone and the appearence of astrocytes between the intermediate zone and the cortical plate, 48 h after intoxification. The activation of glial cells was accompanied by the neuronal expression of c-Fos but not of c-Jun in the ventricular/intermediate zone. Based on our observations on BrdU-incorporation and on the morphological outcome of MAM treatment in the juvenile guinea pig, our data presented here indicate that selective neurodegeneration during development induces the activation of both phagocytotic microglial cells and of astrocytes which might trophically support damaged neurons surviving this lesion procedure.

Amyloid beta-Protein Precursor↗

PubMed2001

Obesity through the ages of man.

From before birth and onwards there is the potential for obesity. Many of the predisposing factors can be prevented or minimised through educational and preventative strategies that support healthier diet and lifestyles, but the need for active treatment and management of obesity has never been greater. Childhood and adolescence are crucial times for prevention, and treatment in middle age confers important health and quality of life benefits. As obesity becomes more prevalent and the population ages, new and inventive strategies are required to tackle this ubiquitous health problem also in older age groups.

Adolescent↗

PubMed2001

Protein kinase Calpha and beta1 isoforms are regulators of alpha-secretory proteolytic processing of amyloid precursor protein in vivo.

We have recently shown that in utero treatment of guinea pigs with the DNA methylating substance methylazoxymethanol acetate (MAM) results in neocortical microencephalopathy, increased protein kinase C (PKC) activity and altered processing of the amyloid precursor protein (APP) in neocortex of offspring. Here we show that PKCalpha and PKCbeta1 are the key regulators of alpha-secretory APP processing in guinea pig neocortex under these experimental conditions in vivo. This conclusion is based on the selective translocation of PKCalpha and PKCbeta1 isoforms to the cell membrane in MAM-treated guinea pigs, as revealed by Western blot analysis and by immunocytochemistry. Additionally, we observed that [3H]phorbol ester binding to protein kinase C increased by 38% and enhanced basal PKC activity by 58% in the neocortex of microencephalic guinea pigs. Inhibition of PKCalpha/PKCbeta1 by Gö6976 abolished this difference, suggesting that constitutive overactivation of these PKC isoforms accounts for the increase in total PKC activity. We also observed a strong positive correlation between levels of alpha-secretase-processed APP and PKC activity in the neocortex of individual animals, providing further evidence for a significant role of classical PKC isoforms in nonamyloidogenic APP processing.

Amyloid beta-Protein Precursor↗

PubMed2001

Increased neuronal and glial expression of protein kinase C isoforms in neocortex of transgenic Tg2576 mice with amyloid pathology.

We investigated the influence of five- to sevenfold neuronal overexpression of the Swedish mutation of human APP695 (APPsw) in the transgenic mouse strain Tg2576 on neocortical protein kinase C (PKC) expression and subcellular distribution. Using specific antibodies to PKC alpha, PKC beta, PKC gamma, PKC epsilon and PKC zeta isoforms for Western blot analysis, we observed increased immunoreactivity for PKC alpha and PKC gamma isoforms in crude tissue homogenates from the neocortex of 16-month-old APPsw mice as compared with nontransgenic littermates, which was not present in 6 month-old Tg2576 mice. We also observed elevated levels of PKC alpha, PKC beta, PKC gamma and PKC zeta in membrane fractions and reduced concentrations of PKC alpha and PKC gamma in cytosolic fractions of aged Tg2576 mice, indicating that these PKC isoforms are in their activated state. In young, 6-month-old Tg2576 mice, however, the increase in membrane-bound PKC isoforms and concomitant decrease in cytosolic PKC isoforms was much less pronounced, demonstrating the age-dependent nature of alterations in PKC isoforms. Immunocytochemistry of brain sections supported these findings and revealed increased neuronal labelling for PKC alpha, PKC gamma and PKC lambda isoforms in neocortex of 16-month-old APPsw mice compared with nontransgenic littermates, with the increase being strongest for PKC gamma and PKC lambda isoforms. Additionally, PKC gamma and to a lesser extent PKC lambda isoforms were induced in reactive astrocytes in proximity to amyloid plaques. Our data indicate that neuronal overexpression of APPsw causes a dynamic change in neuronal expression and activation of multiple PKC isoforms known to be regulators of proteolytic amyloid precursor protein (APP) processing (PKC alpha) and of neuronal survival (PKC lambda and PKC zeta). The induction of the PKC gamma and PKC lambda isoforms in reactive astrocytes surrounding amyloid plaques might be required for astrocyte activation and astrocytic cytokine expression in response to amyloid plaque formation.

Alzheimer Disease↗

PubMed2000

Expression of beta-secretase mRNA in transgenic Tg2576 mouse brain with Alzheimer plaque pathology.

On the basis of the recent cloning of the beta-secretase, the beta-site amyloid precursor protein (APP)-cleaving enzyme (BACE), (Science, 286 (1999) 735), digoxigenin-labelled riboprobes were generated to localize the cellular expression pattern of BACE mRNA in brain sections of transgenic Tg2576 mice, overexpressing the Swedish mutation of the APP695 isoform. Non-radioactive in situ hybridization in combination with immunohistochemistry to identify the cell types and beta-amyloid deposits revealed strong BACE mRNA hybridization signals in neurons of the cerebral cortex, hippocampal formation, thalamus and cholinergic basal forebrain nuclei, while astrocytes did not display any labeling. Neurons surrounding beta-amyloid deposits did not demonstrate altered expression level of BACE mRNA as compared to neurons in cortical areas that are free of beta-amyloid deposits, and the regional expression pattern of BACE mRNA did not correlate with the distribution of beta-amyloid deposits. These data suggest that high level of expression of BACE mRNA is not necessarily related to enhanced deposition of beta-amyloid plaques. To elucidate those factors that contribute to beta-amyloid plaque deposition in a particular region, the transgenic Tg2576 mouse may represent an appropriate tool.

Alzheimer Disease↗

PubMed2000

Intracerebroventricular infusion of CHO5, a rat monoclonal antibody directed against mouse low-affinity nerve growth factor receptor (p75NTR), specifically labels basal forebrain cholinergic neurons in mouse brain.

The finding that basal forebrain cholinergic cells are specifically endowed with the low-affinity nerve growth factor receptor p75NTR has been employed to develop a cholinergic immunotoxin in rats by covalently linking the monoclonal antibody 192IgG against the rat p75NTR with the cytotoxic protein saporin (192IgG-saporin). Following intracebroventricular application of 192IgG-saporin, the antibody conjugate is taken up into cholinergic cells via the p75NTR, retrogradely transported to the cell body, where saporin exerts cytotoxic action. The lack of an appropriate antibody directed against mouse p75NTR has been hampered the development of a mouse-specific cholinergic immunotoxin, which should be a useful tool to study effects of cortical cholinergic deficits on processing of amyloid precursor protein in transgenic mice with Alzheimer pathology. To develop an appropriate mouse-specific immunotoxin, a variety of antibodies directed against mouse p75NTR were tested. Using double labeling immunocytochemistry, the rat monoclonal antibody CHO5 against mouse p75NTR was found to label mouse basal forebrain neurons, which also demonstrated immunoreactivity for choline acetyltransferase and the high-affinity nerve growth factor receptor, TrkA. Intracerebroventricular infusion of CHO5 in mice resulted in an accumulation of the antibody in cholinergic cells within the basal forebrain, suggesting that CHO5 is a suitable candidate to develop a mouse-specific cholinergic immunotoxin.

Animals↗

PubMed2000

In vivo [125I]-iodobenzovesamicol binding reflects cortical cholinergic deficiency induced by specific immunolesion of rat basal forebrain cholinergic system.

In this study, radiolabeled iodobenzovesamicol (IBVM), which is known to bind with high affinity to the vesicular acetylcholine transporter, was tested for its usefulness in imaging cortical cholinergic deficits in vivo. To induce reductions in cortical cholinergic input, the cholinergic immunotoxin 192IgG-saporin was employed. This has been shown to selectively and efficiently destroy basal forebrain cholinergic neurons in rats. The efficiency of the immunolesion was verified by histochemical acetylcholinesterase staining. [125I]-IBVM binding before and after lesioning was measured using autoradiography. Basal forebrain cholinergic cell loss resulted in a considerable reduction in [125I]-IBVM binding in the cholinoceptive target regions, but not in the striatum and cerebellum, brain regions that do not receive a cholinergic input by the basal forebrain cholinergic nuclei, suggesting that [123I]-IBVM has potential in imaging cortical cholinergic deficits in vivo, at least in animals.

Acetylcholinesterase↗

PubMed2000

Constitutive overactivation of protein kinase C in guinea pig brain increases alpha-secretory APP processing without decreasing beta-amyloid generation.

Whilst it is generally accepted that the activation of protein kinase C (PKC) increases amyloid precursor protein (APP) secretion in vitro, the role of PKC in the regulation of APP processing and beta-amyloid generation in vivo is still not well understood. In order to address this question, we established the animal model of neocortical microencephalopathy in guinea pigs caused by in utero treatment with methylazoxymethanol acetate, a DNA-methylating substance that eliminates proliferating cells of neuroepithelial origin. The induction of this neocortical malformation is accompanied by constitutive overactivation of PKC in the neocortex of the offspring. In the cortical and hippocampal tissues of juvenile microencephalic guinea pigs (postnatal day 30), we observed significant increases in basal (by 58% and 74%, respectively,) and phorbol ester-stimulated PKC enzyme activity (by 47% and 71%) as compared to age-matched control animals. In the same cortical/hippocampal preparations of methylazoxymethanol-treated animals, there was increased alpha-secretion of APP by 35% and 30% as measured by Western blot analysis using the antibody 6E10, whilst total APP secretion as well as APP mRNA expression remained unaltered. This upregulation of APP alpha-secretion was limited to brain areas that displayed elevated PKC activity. However, constitutive overactivation of neocortical PKC did not affect the generation of beta-amyloid peptides 1-40 or 1-42 as measured by ELISA, suggesting that only the alpha-secretase pathway of APP processing is affected by chronic PKC overactivation in vivo.

Amyloid Precursor Protein Secretases↗

PubMed2000

Formation and kinetics of MHC class I-ovalbumin peptide complexes on immature and mature murine dendritic cells.

Dendritic cells (DC) are professional antigen-presenting cells that are able to induce primary T cell responses. Therefore, several strategies employ peptide-pulsed DC in tumor immunotherapy. For efficient antigen presentation and induction of an immune response by DC the number and stability of MHC I-peptide complexes is crucial. We studied this issue by using the antibody 25-D1.16 that specifically detects OVA peptide SIINFEKL in conjunction with H-2 Kb molecules, and determined its kinetics on mature and immature bone marrow-derived murine DC. Optimal peptide loading was reached after 8-16 h at 50 microM peptide pulse, and was comparable in serum-free versus serum-containing medium. Stimulation of DC with LPS or Poly I:C, and to a lesser extent TNF-alpha, upregulated the total number of surface MHC I molecules and thus improved peptide loading. Pulse-chase experiments revealed a constant half-life of peptide/Kb complexes independent of preceding DC stimulation or their maturation stage. The duration of peptide/Kb complex expression on mature DC, however, could be extended from 24 h to 72 h when the cultures were pretreated with LPS or Poly I:C, but not TNF-alpha. These data might have important implications for the clinical application of peptide-pulsed DC in tumor immunotherapy.

Aging↗

PubMed1999

Acute effect of KA-672, a putative cognitive enhancer, on neurotransmitter receptor binding in mouse brain.

7-Methoxy-6-[3-[4-(2-methoxyphenyl)piperazin-1-yl]propoxy]-3,4-dim ethyl-2H-1-benzopyran-2-one hydro-chloride (KA-672), structurally related to naturally occurring coumarins, has been described as a potential drug for enhancing cognitive functions. However, a detailed characterization of the pharmacological profile of KA-672 in vivo is still lacking. Quantitative neurotransmitter receptor autoradiography was used as a tool to screen for KA-672-induced changes in a number of transmitter receptors including cholinergic, noradrenergic, glutamatergic, GABAergic, and serotonergic subtypes throughout the brain. Two hours following treatment of mice with 1 mg/kg KA-672 per os, slight increases of nicotinic and M1-muscarinic cholinergic receptor binding, of alpha2-and beta-adrenoceptor as well as 5-HT1A receptors in various cerebral cortical regions were observed, whereas 5-HT2A binding sites were strikingly increased throughout the brain following KA-672 treatment. In contrast, (+/-)-alphaamino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor binding was significantly decreased in some cortical regions after drug treatment. No effects of KA-672 treatment on N-methyl-D-aspartate, kainate, GABA(A) and benzodiazepine receptor as well as M2-muscarinic cholinergic and high-affinity choline uptake binding were observed. As interactions between the cholinergic, noradrenergic and serotonergic neurotransmission have been stressed to play important roles in realizing learning and memory events, the cognition-enhancing effects of KA-672 may be due to this complex in vivo pharmacological profile of KA-672.

Animals↗

PubMed1999

Regulated secretion of amyloid precursor protein by TrkA receptor stimulation in rat pheochromocytoma-12 cells is mitogen activated protein kinase sensitive.

We have shown recently in the pheochromocytoma PC-12 cell line, that the activation of the high-affinity receptor for nerve growth factor (NGF), tyrosine kinase receptor (TrkA), results in increased secretion of the amyloid precursor protein (APP) into the culture medium. In order to reveal through which TrkA-associated signaling pathway the secretory APP processing is mediated, signaling cascades activated by TrkA stimulation were selectively inhibited under conditions of selective TrkA stimulation via non-NGF mechanisms and APP secretion into the culture medium was followed by Western analysis. Our data demonstrate, that activation of mitogen activated protein (MAP) kinase alone is sufficient to promote APP secretion, whereas inhibition of MAP kinase will reduce APP secretion only when phospholipase Cgamma or phosphatidylinositol 3-kinase are additionally inhibited. This suggests that pharmacological manipulations activating the MAP kinase pathway may result in increased secretory APP processing.

Amyloid beta-Protein Precursor↗

PubMed1999

Leukemia inhibitory factor expression is not induced in activated microglia and reactive astrocytes in response to rat basal forebrain cholinergic lesion.

In adult intact rat brain, leukemia inhibitory factor (LIF) mRNA has been found to be constitutively expressed in basal forebrain cholinergic neurons. To reveal a functional role of LIF in neurodegenerative events, the cellular expression pattern of LIF was determined by combining in situ hybridization and immunocytochemistry after specific and selective degeneration of basal forebrain cholinergic cells by a single intracerebroventricular application of the cholinergic immunotoxin 192IgG-saporin. Although basal forebrain cholinergic lesion resulted in a dramatic activation of micro- and astroglial cells at the lesion site, LIF mRNA expression was not detected in any of the lesion-induced activated glial cell types. As the cholinergic immunotoxin exerts its degenerative action by the ribosome-inactivating property of saporin, the lack of glial LIF induction might be due to the incapability of the dying cholinergic cell to form and release factors which induce LIF expression in activated glial cells.

Animals↗

PubMed1999

Iodo-QNB cortical binding and brain perfusion: effects of a cholinergic basal forebrain lesion in the rat.

This study deals with the question of whether in vivo application of [125I]iodo-quinuclidinyl-benzilate (QNB) is able to demonstrate changes in cortical muscarinic receptor density induced by a cholinergic immunolesion of the rat basal forebrain cholinergic system, and whether the potential effects on IQNB distribution in vivo are also associated with effects on regional cerebral perfusion. Immunolesioned and control animals were injected with (R,S) [125]iodo-QNB and with [99mTc]-d,l-hexamethylpropyleneamine oxime (HMPAO). The cerebral distribution of both tracers was imaged using double tracer autoradiography. Impaired cholinergic transmission was paralleled by a 10-15% increase of [125I]iodo-QNB binding in the regions of cortex and hippocampus. The local cerebral blood flow remained unchanged after cholinergic lesion.

Acetylcholine↗