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1.
Zhongguo Xue Xi Chong Bing Fang Zhi Za Zhi ; 31(5): 463-467, 2019 Sep 27.
Article Zh | MEDLINE | ID: mdl-31713372

OBJECTIVE: To understand the situation of Schistosoma japonicum infections in wild animals in transmission-controlled schistosomiasis-endemic areas in Jiangxi Province, so as to provide scientific evidence for implementing precision control interventions and achieving the goal of transmission interruption and elimination of schistosomiasis. METHODS: Five endemic villages from Ruichang City and Pengze County that were heavily endemic for schistosomiasis in Jiangxi Province, were selected as the study villages. Wild animals like wild mice were captured, and the livers of wild animals were purchased from the snail habitats in the study villages for detection of S. japonicum infections. In the study villages, S. japonicum human infections were screened using indirect hemagglutination assay (IHA) followed by parasitological examinations with miracidial hatching test and Kato-Katz method, and the S. japonicum infection in livestock was tested using a miracidial hatching test with a plastic tube. In addition, snail survey was conducted in the study villages by means of systematic sampling combined with environmental sampling, and the S. japonicum infection in snails was detected using a loop-mediated isothermal amplification (LAMP) assay. RESULTS: A total of 240 liver specimens were sampled or purchased from 5 species of wild animals in the study villages, including wild mice, weasels, pigs, deer and rabbits. A total of 172 wild mice were captured, with a 2.91% rate of S. japonicum infection, and there was no S. japonicum infection detected in other wild animals. The prevalence of Capillaria hepatica infection was 12.21%, 1.96% and 12.50% in wild mice, deer and pigs, respectively. In addition, there was no S. japonicum infection found in either humans or livestock in the study villages, and the mean snail density varied from 0.13 to 0.80 snails/0.1 m2 in the study villages. LAMP assay detected S. japonicum infection in 2 tubes in a study village. CONCLUSIONS: The role of wild animals in schistosomiasis transmission and their potential risks can not be neglected in hilly schistosomiasis-endemic areas of Jiangsu Province after transmission control. Intensified surveillance and targeted control measures should be implemented to consolidate schistosomiasis control achievements.


Animals, Wild , Schistosoma japonicum , Schistosomiasis japonica , Animals , Animals, Wild/parasitology , China/epidemiology , Humans , Liver/parasitology , Mice , Population Density , Prevalence , Rabbits , Schistosomiasis japonica/epidemiology , Schistosomiasis japonica/prevention & control , Snails/physiology , Surveys and Questionnaires , Swine
2.
Oncogene ; 33(13): 1700-12, 2014 Mar 27.
Article En | MEDLINE | ID: mdl-23624923

Melanoma is an aggressive skin cancer that carries an extremely poor prognosis when local invasion, nodal spread or systemic metastasis has occurred. Recent advances in melanoma biology have revealed that RAS-RAF-MEK-ERK signaling has a pivotal role in governing disease progression and treatment resistance. Proof-of-concept clinical studies have shown that direct BRAF inhibition yields impressive responses in advanced disease but these are short-lived as treatment resistance rapidly emerges. Therefore, there is a pressing need to develop new targeted strategies for BRAF mutant melanoma. As such, oncolytic viruses represent a promising cancer-specific approach with significant activity in melanoma. This study investigated interactions between genetically-modified vaccinia virus (GLV-1h68) and radiotherapy in melanoma cell lines with BRAF mutant, Ras mutant or wild-type genotype. Preclinical studies revealed that GLV-1h68 combined with radiotherapy significantly increased cytotoxicity and apoptosis relative to either single agent in (V600D)BRAF/(V600E)BRAF mutant melanoma in vitro and in vivo. The mechanism of enhanced cytotoxicity with GLV-1h68/radiation (RT) was independent of viral replication and due to attenuation of JNK, p38 and ERK MAPK phosphorylation specifically in BRAF mutant cells. Further studies showed that JNK pathway inhibition sensitized BRAF mutant cells to GLV-1h68-mediated cell death, mimicking the effect of RT. GLV-1h68 infection activated MAPK signaling in (V600D)BRAF/(V600E)BRAF mutant cell lines and this was associated with TNF-α secretion which, in turn, provided a prosurvival signal. Combination GLV-1h68/RT (or GLV-1h68/JNK inhibition) caused abrogation of TNF-α secretion. These data provide a strong rationale for combining GLV-1h68 with irradiation in (V600D/E)BRAF mutant tumors.


JNK Mitogen-Activated Protein Kinases/genetics , Melanoma/therapy , Oncolytic Virotherapy/methods , Proto-Oncogene Proteins B-raf/genetics , Tumor Necrosis Factor-alpha/metabolism , Vaccinia virus/physiology , Animals , Cell Death , Cell Line, Tumor , Female , Humans , JNK Mitogen-Activated Protein Kinases/antagonists & inhibitors , JNK Mitogen-Activated Protein Kinases/metabolism , MAP Kinase Signaling System , Melanoma/genetics , Melanoma/metabolism , Melanoma/virology , Mice , Mice, Inbred BALB C , Mice, Nude , Random Allocation , Tumor Necrosis Factor-alpha/genetics , Xenograft Model Antitumor Assays
3.
Cancer Lett ; 344(2): 282-90, 2014 Mar 28.
Article En | MEDLINE | ID: mdl-24321381

Combining oncolytic viruses with conventional therapy such as radiation is an innovative option for pancreatic cancer. We demonstrated that combination of GLV-1h151 and radiation yielded a synergistic cytotoxic effect, with the greatest effect achieved in the AsPC-1cell line. Combination treatment significantly increased apoptosis compared with either single treatment or the control group. In mice bearing human pancreatic tumor xenografts, combination treatment resulted in significantly enhanced inhibition of tumor growth. No evidence of toxicity was observed in mice. These results indicate that the combination of GLV-1h151 and radiation has great potential for translation into clinic practice.


Adenocarcinoma/therapy , Oncolytic Virotherapy/methods , Pancreatic Neoplasms/therapy , Vaccinia virus/physiology , Adenocarcinoma/radiotherapy , Adenocarcinoma/virology , Animals , Cell Line, Tumor , Combined Modality Therapy , Humans , Mice , Mice, Inbred BALB C , Pancreatic Neoplasms/radiotherapy , Pancreatic Neoplasms/virology , Random Allocation , Xenograft Model Antitumor Assays
4.
Ultrasound Med Biol ; 35(5): 813-28, 2009 May.
Article En | MEDLINE | ID: mdl-19345468

Previous studies indicate imaging of ultrasound contrast in 3-D is potentially superior to 2-D imaging for vascular characterization. A dual-beam, dynamic refill technique, which relies on volumetric contrast clearance and sequential imaging, was used to image a preserved porcine kidney perfused with contrast. A model was developed for the contrast profile across the renal artery to estimate fractional blood volume. This model was used along with refill curve information to measure absolute perfusion within renal cortex for a 100-cm(3) volume. Perfusion measurements from a slice within the volume were also made using a modified interval imaging technique. The measured perfusion using the dual-beam technique was consistent with the perfusion measured using the interval imaging technique (dual-beam values were 1.06 +/- 0.04 x corresponding interval imaging values). These experiments suggest that ultrasound contrast perfusion measurements are independent of the volume of contrast eliminated before refill.


Imaging, Three-Dimensional/methods , Kidney/diagnostic imaging , Animals , Contrast Media/pharmacokinetics , Models, Cardiovascular , Phantoms, Imaging , Renal Artery/diagnostic imaging , Renal Circulation , Sus scrofa , Transducers , Ultrasonography
5.
Biochem Biophys Res Commun ; 282(3): 717-22, 2001 Apr 06.
Article En | MEDLINE | ID: mdl-11401521

Our previous work has shown that troglitazone (an antidiabetic, thiazolidione drug and a synthetic ligand for peroxisome proliferator-activated receptor gamma, PPARgamma) stimulated basal level of intercellular adhesion molecule-1 (ICAM-1) protein expression in the absence of cytokine stimulation in human vascular endothelial cells. In this study, we examine the molecular mechanism of troglitazone on the basal and TNFalpha-induced ICAM-1 gene expression. Activation of transcription factors, NF-kappaB and AP-1 proteins, known to regulate ICAM-1 gene expression upon external stimulators, was examined. In human vascular endothelial cells (ECV304 cells), troglitazone inhibited TNFalpha-induced ICAM-1 gene expression by suppressing NF-kappaB/DNA binding activity, NF-kappaB transcriptional responses, c-Fos mRNA and protein levels via a ligand-dependent, PPARgamma-activated manner. In contrast, both troglitazone (at 10 microM) and 15-deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2), at 15 microM), a natural ligand for PPARgamma, induce c-Jun phosphorylation by activation of c-Jun N-terminal kinase (JNK) through a posttranslational regulation of c-Jun activity, therefore increasing AP-1/DNA binding activity and transcriptional responses as results of increasing basal ICAM-1 gene expression. These findings suggest dual function of troglitazone in the modulation of both basal and stimulated ICAM-1gene expression in human vascular endothelial cells.


Chromans/pharmacology , Endothelium, Vascular/drug effects , Endothelium, Vascular/metabolism , Intercellular Adhesion Molecule-1/genetics , Thiazoles/pharmacology , Thiazolidinediones , Base Sequence , Cell Line, Transformed , DNA Primers/genetics , Enzyme Activation/drug effects , Gene Expression/drug effects , Genes, fos/drug effects , Humans , Hypoglycemic Agents/pharmacology , Intercellular Adhesion Molecule-1/metabolism , JNK Mitogen-Activated Protein Kinases , Mitogen-Activated Protein Kinases/metabolism , NF-kappa B/metabolism , Prostaglandin D2/analogs & derivatives , Prostaglandin D2/pharmacology , Proto-Oncogene Proteins c-fos/genetics , Proto-Oncogene Proteins c-fos/metabolism , RNA, Messenger/genetics , RNA, Messenger/metabolism , Receptors, Cytoplasmic and Nuclear/metabolism , Transcription Factor AP-1/metabolism , Transcription Factors/metabolism , Troglitazone , Tumor Necrosis Factor-alpha/pharmacology
6.
Appl Opt ; 40(19): 3288-303, 2001 Jul 01.
Article En | MEDLINE | ID: mdl-11958271

A total of 364 optical source-detector pairs were deployed uniformly over a 9 cm x 9 cm probe area initially, and then the total pairs were reduced gradually to 60 in experimental and simulation studies. For each source-detector configuration, three-dimensional (3-D) images of a 1-cm-diameter absorber of different contrasts were reconstructed from the measurements made with a frequency-domain system. The results have shown that more than 160 source-detector pairs are needed to reconstruct the absorption coefficient to within 60% of the true value and appropriate spatial and contrast resolution. However, the error in target depth estimated from 3-D images was more than 1 cm in all source-detector configurations. With the a priori target depth information provided by ultrasound, the accuracy of the reconstructed absorption coefficient was improved by 15% and 30% on average, and the beam width was improved by 24% and 41% on average for high- and low-contrast cases, respectively. The speed of reconstruction was improved by ten times on average.

7.
Appl Opt ; 40(34): 6367-80, 2001 Dec 01.
Article En | MEDLINE | ID: mdl-18364946

We have constructed a near-real-time combined imager suitable for simultaneous ultrasound and near-infrared diffusive light imaging and coregistration. The imager consists of a combined hand-held probe and the associated electronics for data acquisition. A two-dimensional ultrasound array is deployed at the center of the combined probe, and 12 dual-wavelength laser source fibers (780 and 830 nm) and 8 optical detector fibers are deployed at the periphery. We have experimentally evaluated the effects of missing optical sources in the middle of the combined probe on the accuracy of the reconstructed optical absorption coefficient and assessed the improvements of a reconstructed absorption coefficient with the guidance of the coregistered ultrasound. The results have shown that, when the central ultrasound array area is in the neighborhood of 2 cm x 2 cm, which corresponds to the size of most commercial ultrasound transducers, the optical imaging is not affected. The results have also shown that the iterative inversion algorithm converges quickly with the guidance of a priori three-dimensional target distribution, and only one iteration is needed to reconstruct an accurate optical absorption coefficient.

8.
Atherosclerosis ; 152(1): 203-8, 2000 Sep.
Article En | MEDLINE | ID: mdl-10996356

This study was initiated to describe the relationships between plasma glucose and insulin responses to oral glucose and the concentrations of partially oxidized low density lipoprotein (poxLDL) and soluble intercellular adhesion molecule-1 (sICAM-1) in 23 healthy, non-diabetic volunteers. Results demonstrated that plasma glucose (r=0.65, P<0.002) and insulin (r=0.58, P<0.007) responses to a 75-g oral glucose challenge were highly correlated to poxLDL concentrations. Plasma glucose (r=0.63, P<0.002) and insulin (r=0.68, P<0.001) concentrations also significantly correlated with sICAM-1 concentrations. Furthermore, concentrations of poxLDL and sICAM-1 were significantly related (r=0.55, P<0.001). These relationships remained statistically significant when adjusted for differences in age, gender, body mass index, and lipoprotein concentrations. These results provide further evidence that circulating LDL particles are more highly oxidized in insulin resistant states, and demonstrate the presence of an in vivo relationship between insulin resistance, LDL oxidized state, and sICAM-1 concentrations. These results help explain why soluble forms of adhesion molecules are increased in clinical conditions characterized by insulin resistance, and support the possibility that LDL oxidizability is increased in insulin resistant subjects, and that the increase in sICAM-1 results from stimulation of cellular adhesion molecules by more highly oxidized LDL.


Blood Glucose/drug effects , Blood Glucose/metabolism , Insulin/administration & dosage , Intercellular Adhesion Molecule-1/blood , Lipoproteins, LDL/metabolism , Administration, Oral , Adult , Aged , Female , Glucose Tolerance Test , Humans , Insulin Resistance , Intercellular Adhesion Molecule-1/drug effects , Lipid Peroxidation , Lipoproteins, LDL/drug effects , Male , Middle Aged , Multivariate Analysis , Probability , Reference Values , Regression Analysis , Solubility
9.
J Clin Endocrinol Metab ; 84(10): 3485-9, 1999 Oct.
Article En | MEDLINE | ID: mdl-10522984

The relationship between insulin resistance, soluble adhesion molecules E-selectin (sE-selectin), intracellular adhesion molecule-1 (sICAM-1), and vascular adhesion molecule-1 (sVCAM-1), mononuclear cell binding to cultured endothelium, and lipoprotein concentrations were evaluated in 28 healthy, nondiabetic, and normotensive individuals. The mean (+/-SEM) lipid and lipoprotein concentrations were within the normal rage: cholesterol (199 +/- 18 mg/dL); triglyceride (128 +/- 12 mg/dL); low-density cholesterol (127 +/- 8 mg/dL; and high-density cholesterol (47 +/- 3 mg/dL). The results indicated that degree of insulin resistance was significantly correlated with concentrations of sE-selectin (r = 0.54, P < 0.005), sICAM-1 (r = 0.67, P < 0.001), and sVCAM-1 (r = 0.41, P < 0.05). Furthermore, the relationship between insulin resistance and both sE-selectin and sI-CAM-1 remained statistically significant when adjusted for differences in age, gender, body mass index, and all measures of lipoprotein concentrations. Finally, mononuclear cell binding correlated significantly with concentrations of sE-selectin (r = 0.54, P < 0.005) and sICAM-1 (r = 0.47, P < 0.01). These findings raise the possibility that previously described relationships between soluble adhesion molecules in patients with hypertension, type 2 diabetes, and dyslipidemia may be due to the presence of insulin resistance in these clinical syndromes and suggests that insulin resistance may predispose individuals to coronary heart disease by activation of cellular adhesion molecules.


Cell Adhesion Molecules/blood , Insulin Resistance , Monocytes/metabolism , Aged , E-Selectin/blood , Female , Humans , Intercellular Adhesion Molecule-1/blood , Male , Middle Aged , Reference Values , Solubility , Vascular Cell Adhesion Molecule-1/blood
10.
Biochem Biophys Res Commun ; 263(3): 718-22, 1999 Oct 05.
Article En | MEDLINE | ID: mdl-10512746

Early atherosclerotic lesions are characterized by increased monocyte adhesion to the overlying endothelium. Oxidized LDL (oxLDL) stimulates the adhesion of human monocytes to endothelial cells, in part, by increasing expression of ICAM-1. However, the cellular role of oxLDL in endothelial adhesiveness is not well understood. The peroxisome proliferator-activated receptor gamma (PPARgamma), a member of the nuclear receptor superfamily, is expressed in vascular endothelial cells. Whether it can be activated by a synthetic ligand, troglitazone, as well as by natural ligands, oxLDL and its lipid components (i.e., 9- and 13-HODE), has not yet been explored. This study was undertaken to determine whether PPARgamma is expressed in ECV304 human vascular endothelial cells and if so to define the biological effects of its activation by these agonists. Our results demonstrate that PPARgamma mRNA is expressed in ECV304 cells, and transfected cells with a PPARE luciferase construct respond to these agonists. In addition, ligand-dependent PPARgamma activation increased ICAM-1 protein expression and enhanced adherence of monocytes to ECV304 cells by two- to threefold. These findings suggest that the PPARgamma signaling pathway might contribute to the atherogenicity of oxLDL in vascular endothelial cells.


Cell Adhesion/physiology , Endothelium, Vascular/physiology , Gene Expression Regulation/drug effects , Intercellular Adhesion Molecule-1/genetics , Linoleic Acids, Conjugated , Receptors, Cytoplasmic and Nuclear/agonists , Thiazolidinediones , Transcription Factors/agonists , Antioxidants/pharmacology , Cell Adhesion/drug effects , Cell Line, Transformed , Chromans/pharmacology , DNA-Binding Proteins/agonists , DNA-Binding Proteins/drug effects , Endothelium, Vascular/drug effects , Humans , Linoleic Acids/pharmacology , Lipopolysaccharides/pharmacology , Lipoproteins, LDL/pharmacology , Receptors, Cytoplasmic and Nuclear/drug effects , Receptors, Cytoplasmic and Nuclear/genetics , Recombinant Proteins/agonists , Recombinant Proteins/drug effects , Reverse Transcriptase Polymerase Chain Reaction , Thiazoles/pharmacology , Transcription Factors/drug effects , Transcription Factors/genetics , Transfection , Troglitazone , Tumor Necrosis Factor-alpha/pharmacology , Umbilical Veins
11.
Metabolism ; 48(10): 1314-7, 1999 Oct.
Article En | MEDLINE | ID: mdl-10535396

A study was initiated to test two hypotheses. The first was the postulate that glucose-stimulated insulin secretion would be enhanced in pancreatic islets isolated from normal non-obese rats made insulin-resistant by dietary means. The second, related hypothesis was that glucose-stimulated insulin secretion by pancreatic islets isolated from insulin-resistant rats would be more vulnerable to inhibition following culture in the presence of fatty acids. For this purpose, insulin resistance was induced in normal Sprague-Dawley rats by feeding fat-enriched and fructose-enriched diets. The results indicate that islets isolated from either fat-fed or fructose-fed rats secreted significantly more insulin at a glucose concentration of 2.5 to 10.0 mmol/L. In addition, the mean maximal glucose (27 mmol/L)-stimulated insulin secretion rate was significantly lower (15.3 +/- 2.5 ng/islet/h) in islets from fructose-fed rats versus chow-fed rats (25.2 +/- 3.1 ng/islet/h) following culture for 48 hours in the presence of palmitate (0.125 micromol/L). These results support the view that glucose-stimulated insulin secretion is enhanced in islets from insulin-resistant rats, and that these islets are more vulnerable to the inhibitory effects of free fatty acid (FFA) on insulin secretion.


Dietary Fats/pharmacology , Glucose/pharmacology , Insulin Resistance , Insulin/metabolism , Islets of Langerhans/metabolism , Palmitic Acid/pharmacology , Analysis of Variance , Animals , Cells, Cultured , Diet , Fructose/administration & dosage , Fructose/pharmacology , In Vitro Techniques , Insulin Secretion , Islets of Langerhans/drug effects , Kinetics , Male , Rats , Rats, Sprague-Dawley
12.
Circulation ; 100(9): 940-3, 1999 Aug 31.
Article En | MEDLINE | ID: mdl-10468524

BACKGROUND: This study was initiated to compare the adherence to cultured endothelial cells of mononuclear cells isolated from normotensive and hypertensive individuals. METHODS AND RESULTS: Mononuclear cell binding to endothelium was greater in patients with hypertension (32+/-1 versus 25+/-2; P<0.001) than in normal volunteers. There was a significant relationship (r=0.42, P<0. 01) between mononuclear cell binding and mean arterial pressure, independent of differences in age, sex, and body mass index. A significant relationship also existed between insulin resistance (estimated by the steady-state plasma glucose concentration during the insulin suppression test) and mononuclear cell binding in both the normotensive (r=0.86, P<0.001) and hypertensive (r=0.74, P<0. 001) groups. Furthermore, multiple regression analysis demonstrated an independent relationship (P<0.001) between mononuclear cell binding and both steady-state plasma glucose and hypertensive status. CONCLUSIONS: These results indicate that both hypertension and insulin resistance lead to changes in mononuclear cells that increase their adherence to cultured endothelial cells.


Endothelium, Vascular/cytology , Hypertension/pathology , Insulin Resistance , Leukocytes, Mononuclear/pathology , Cell Adhesion , Cells, Cultured , Endothelium, Vascular/pathology , Female , Humans , Male , Middle Aged , Regression Analysis , Volunteers
13.
Phys Med Biol ; 44(7): 1669-76, 1999 Jul.
Article En | MEDLINE | ID: mdl-10442704

We have developed a controlled Monte Carlo (CMC) method to calculate the time-dependent transmittance of light through a thick tissue, especially for evaluation of the contribution from early arriving photons. Quasi-straightforward propagating trajectories are favoured according to a selection mechanism, so adequate trajectories of interest can reach the detector, improving the statistics dramatically. Simulations were conducted for tissue models with a thickness of 3-5 cm, and with optical properties similar to human breast tissue. Temporal profiles of early transmittance were obtained with satisfactory convergence. In addition, comparison was made with the conventional Monte Carlo approach to verify our scheme when applied to cases of optically thin tissues.


Breast , Light , Mammography , Photons , Algorithms , Computer Simulation , Female , Humans , Monte Carlo Method , Time Factors
14.
J Clin Invest ; 100(5): 1174-9, 1997 Sep 01.
Article En | MEDLINE | ID: mdl-9276734

Hypersecretion of insulin from the pancreas is among the earliest detectable metabolic alterations in some genetically obese animals including the ob/ob mouse and in some obesity-prone humans. Since the primary cause of obesity in the ob/ob mouse is a lack of leptin due to a mutation in the ob gene, we tested the hypothesis that leptin targets a regulatory pathway in pancreatic islets to prevent hypersecretion of insulin. Insulin secretion is regulated by changes in blood glucose, as well as by peptides from the gastrointestinal tract and neurotransmitters that activate the pancreatic islet adenylyl cyclase (e.g., glucagon-like peptide-1) and phospholipase C (PLC) (e.g., acetylcholine) signaling pathways to further potentiate glucose-induced insulin secretion. Effects of leptin on each of these regulatory pathways were thus examined. Leptin did not influence glucose or glucagon-like peptide-1-induced insulin secretion from islets of either ob/ob or lean mice, consistent with earlier findings that these regulatory pathways do not contribute to the early-onset hypersecretion of insulin from islets of ob/ob mice. However, leptin did constrain the enhanced PLC- mediated insulin secretion characteristic of islets from ob/ob mice, without influencing release from islets of lean mice. A specific enhancement in PLC-mediated insulin secretion is the earliest reported developmental alteration in insulin secretion from islets of ob/ob mice, and thus a logical target for leptin action. This action of leptin on PLC-mediated insulin secretion was dose-dependent, rapid-onset (i.e., within 3 min), and reversible. Leptin was equally effective in constraining the enhanced insulin release from islets of ob/ob mice caused by protein kinase C (PKC) activation, a downstream mediator of the PLC signal pathway. One function of leptin in control of body composition is thus to target a PKC-regulated component of the PLC-PKC signaling system within islets to prevent hypersecretion of insulin.


Acetylcholine/pharmacology , Insulin/metabolism , Islets of Langerhans/metabolism , Obesity/metabolism , Proteins/pharmacology , Animals , Insulin Secretion , Leptin , Mice , Mice, Obese , Phosphorylation , Protein Kinase C/physiology , Type C Phospholipases/physiology
15.
Am J Physiol ; 272(2 Pt 1): E304-11, 1997 Feb.
Article En | MEDLINE | ID: mdl-9124339

Islets from 2-wk-old ob/ob and lean littermate mice were cultured for 4-12 days and then perifused or statically incubated to identify early-onset differences in their regulation of insulin secretion. Islets from these young ob/ob and lean mice increased insulin secretion similarly in response to glucose (10 or 20 mM), whereas responsiveness to glucose plus acetylcholine (10 microM) was greater in islets from ob/ob mice than lean mice. This phenotype-specific effect of acetylcholine was mimicked by phorbol 12-myristate 13-acetate (PMA, 100 nM), a protein kinase C (PKC) agonist, whereas prior downregulation of PKC abolished this phenotype-specific effect of acetylcholine. A high concentration of PMA (1 microM) equally and substantially increased insulin secretion from islets of ob/ob and lean mice, suggesting an enhanced regulatory sensitivity rather than altered responsiveness of the PKC system in islets of ob/ob mice. Addition of BAY K 8644, a Ca2+ channel agonist, to the perifusate enhanced acetylcholine-induced insulin secretion from islets of lean mice to attain the high rates observed in islets from ob/ob mice exposed to acetylcholine alone. We propose that acetylcholine-induced PKC regulation of insulin secretion is altered in islets from ob/ob mice, that this alteration may directly or indirectly involve Ca2+ channels, and that it persists even when islets are cultured for up to 12 days.


Insulin/metabolism , Islets of Langerhans/drug effects , Islets of Langerhans/metabolism , Obesity/metabolism , Protein Kinase C/pharmacology , 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester/pharmacology , Acetylcholine/pharmacology , Animals , Animals, Newborn , Calcium Channel Agonists/pharmacology , Calcium Channels/physiology , Electrophysiology , Female , In Vitro Techniques , Insulin Secretion , Mice , Mice, Mutant Strains/genetics , Obesity/genetics , Reference Values , Tetradecanoylphorbol Acetate/pharmacology
16.
J Nutr ; 125(3): 503-11, 1995 Mar.
Article En | MEDLINE | ID: mdl-7876925

Consumption of a glucose diet for 4 d markedly elevates plasma insulin concentrations in adrenalectomized ob/ob mice. The present study examined regulation of insulin secretion from perifused pancreatic islets of female adrenalectomized genetically obese (ob/ob) and lean mice fed a glucose diet for 4 d. These mice were fed a high carbohydrate commercial diet for 21 d, or the high carbohydrate commercial diet for 17 d and a purified high glucose diet for the last 4 d of the 21-d feeding period. Adrenalectomy equalized plasma insulin concentrations, pancreatic islet size, rates of insulin secretion in response to 20 mmol/L glucose and insulin mRNA relative abundance in ob/ob and lean mice fed the commercial diet, but the threshold for glucose-induced insulin secretion determined by a linear glucose gradient remained lower in islets from adrenalectomized ob/ob mice than in those from lean mice (3.8 +/- 0.1 vs. 4.9 +/- 0.2 mmol/L glucose), and addition of acetylcholine to the perifusate lowered the threshold to only 2.0 +/- 0.1 mmol/L glucose in islets from ob/ob mice vs. 3.3 +/- 0.1 mmol/L glucose in lean mice. Switching from the commercial diet to the glucose diet for 4 d increased plasma insulin concentrations -10-fold in islets from adrenalectomized ob/ob mice without affecting islet size, 20 mmol/L glucose-induced insulin secretion or insulin mRNA abundance. Consumption of the glucose diet did, however, markedly lower the threshold for glucose-induced insulin secretion in islets from adrenalectomized ob/ob mice to approximate the abnormally low glucose thresholds in intact ob/ob mice.(ABSTRACT TRUNCATED AT 250 WORDS)


Adrenalectomy , Dietary Carbohydrates/administration & dosage , Glucose/administration & dosage , Insulin/metabolism , Islets of Langerhans/drug effects , Obesity/physiopathology , Acetylcholine/metabolism , Animals , Female , Glucose/pharmacology , Insulin/genetics , Insulin Secretion , Islets of Langerhans/metabolism , Kinetics , Mice , Mice, Obese , Phenotype , RNA, Messenger/metabolism
17.
Endocrinology ; 136(2): 505-11, 1995 Feb.
Article En | MEDLINE | ID: mdl-7835283

Insulin secretion from perifused islets of preobese, 2-week-old, genetically obese (ob/ob) mice and their lean littermates was examined to identify early-onset abnormalities in regulation of insulin secretion by ob/ob mice. The ob/ob mice were slightly hyperinsulinemic (+20%) and hypoglycemic (-12%) at 2 weeks of age. Pancreatic islet size, DNA content, and insulin content were similar in ob/ob and lean mice. The responsiveness of islets to glucose, as determined by 20 mM glucose-induced insulin secretion, and the sensitivity of islets to glucose, as determined by the glucose threshold for insulin secretion, were unaffected by phenotype, but two insulin secretagogues that potentiate glucose-induced insulin secretion via activation of the phospholipase-C signal transduction pathway (i.e. acetylcholine, and cholecystokinin) were more effective in stimulating insulin secretion from islets of ob/ob mice than from islets of lean mice. Both responsiveness and sensitivity to acetylcholine and cholecystokinin potentiation of glucose-induced insulin secretion were enhanced in islets from ob/ob mice. Further, glucose-dependent insulinotropic polypeptide, which stimulates glucose-induced insulin secretion via activation of adenylate cyclase, interacted with acetylcholine to further augment differences in insulin secretion between islets from ob/ob and lean mice. The signal transduction pathway common to acetylcholine and cholecystokinin, and cross-talk between this pathway and the glucose-dependent insulinotropic polypeptide signal transduction pathway are loci for early-onset defects in control of insulin secretion from islets of ob/ob mice.


Acetylcholine/pharmacology , Cholecystokinin/pharmacology , Gastric Inhibitory Polypeptide/pharmacology , Insulin/metabolism , Islets of Langerhans/metabolism , Animals , Drug Synergism , Female , Glucose/pharmacology , In Vitro Techniques , Insulin Secretion , Mice , Mice, Obese , Signal Transduction , Type C Phospholipases/metabolism
18.
J Nutr ; 123(9): 1567-74, 1993 Sep.
Article En | MEDLINE | ID: mdl-8360782

Pancreatic islets were isolated from 8-9-wk-old female genetically obese (ob/ob) and lean mice to determine the glucose threshold for insulin secretion, and to examine effects of acetylcholine on insulin secretion. Only equal-sized islets from ob/ob and lean mice were incubated to eliminate confounding effects of phenotypic differences in islet size. Even after this adjustment, islets from ob/ob mice still hypersecreted insulin in response to 20 mmol/L glucose. The threshold for glucose-induced insulin secretion determined by perifusing islets with a linear glucose gradient averaged 1.9 +/- 0.1 mmol/L glucose in fed ob/ob mice and 3.1 +/- 0.1 mmol/L glucose in ob/ob mice after 24 h of food deprivation. These low thresholds indicate that islets from ob/ob mice are constantly stimulated by glucose. Islets from lean mice exhibited considerably higher thresholds (4.8 +/- 0.1 and 7.1 +/- 0.1 mmol/L glucose in fed and 24-h food-deprived lean mice, respectively). Rates of insulin secretion per each unit (mmol/L) increase in glucose above threshold concentrations were unaffected by phenotype or feeding state. Addition of acetylcholine to the perifusing buffer further lowered the threshold for insulin secretion to 0.5 mmol/L glucose in pancreatic islets from ob/ob mice and also doubled the rate of increase in insulin secretion at glucose concentrations above the threshold. The combination of the very low threshold for glucose-induced insulin secretion and the exaggerated insulin secretory response to acetylcholine in pancreatic islets of ob/ob mice are likely critical factors in the hyperinsulinemia of these mice.


Glucose/pharmacology , Insulin/metabolism , Islets of Langerhans/metabolism , Obesity/metabolism , Acetylcholine/pharmacology , Analysis of Variance , Animals , Blood Glucose/analysis , Body Weight , Dose-Response Relationship, Drug , Female , In Vitro Techniques , Insulin Secretion , Islets of Langerhans/drug effects , Mice , Mice, Inbred C57BL , Time Factors
19.
Gene ; 70(2): 405-9, 1988 Oct 30.
Article En | MEDLINE | ID: mdl-2850972

Partial digestion of a target DNA fragment with 4-bp-recognition restriction enzymes followed by a forced ligation to an M13 vector was employed for the construction of a subfragment library. The library can be used for either shotgun or non-random nucleotide sequencing. Application of the partial digests generated with the 4-bp recognition restriction enzymes instead of DNase I in the improved non-random strategy for nucleotide sequencing (Li and Wu, 1987) made the procedure as easy as that of the random strategy. The library can also be used in shotgun nucleotide sequencing directly, and few self-ligated subfragments were found. The usefulness of this procedure was demonstrated by the sequencing of a goat 6.5-kb EcoRI fragment, which is located 5' to the epsilon globin gene.


DNA , Genetic Techniques , Animals , Base Sequence , Cloning, Molecular , DNA Restriction Enzymes , Goats
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