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J P Henry

Publications and source records attributed to J P Henry.

At least 19 recordsLinked to original sources
PubMed2000

Vesicular monoamine transporter 2 as a marker of gastric enterochromaffin-like cell tumors.

The vesicular monoamine transporter 2 (VMAT2) facilitates the ATP-dependent accumulation of biogenic amine inside the secretory granules of endocrine cells and neurons and was demonstrated in the histamine-producing enterochromaffin-like (ECL) cells of the stomach. In the present investigation, VMAT2 immunohistochemistry was tested in 85 endocrine tumors, of which 60 were well differentiated gastrointestinal and pancreatic growths, 5 poorly differentiated (neuro)endocrine carcinomas (PDEC) and 1 mixed PDEC/ECL cell carcinoma of the stomach, 12 pheochromocytomas/paragangliomas, 3 adrenocortical lesions, 2 parathyroid and 2 lung neuroendocrine tumors. Extensive and intense VMAT2 immunoreactivity was observed in 16 of 16 gastric ECL cell tumors, 6 of 6 adrenal pheochromocytomas, 2 of 2 chromaffin paragangliomas and in 3 of the 4 carotid body paragangliomas investigated. Rare VMAT2-positive cells were observed in 12 of 21 intestinal enterochromaffin (EC) cell tumors, in 9 of 11 pancreatic neuroendocrine tumors, and in the mixed PDEC/ ECL cell carcinoma of the stomach (differentiated cells only). No VMAT2 immunoreactivity was observed in five gastrin, four somatostatin and three enteroglucagon/peptideYY tumors of the gastrointestinal tract, in six gastric PDECs, in three adrenocortical growths, and two parathyroid and two lung neuroendocrine tumors. These data support VMAT2 immunohistochemistry as being a useful tool for the diagnosis of gastric ECL cell tumors, separating them from all other endocrine tumors arising in the gastroduodenal area i.e., gastrin, somatostatin, EC cell and PDEC tumors, all of which proved essentially negative.

Biomarkers, Tumor↗
PubMed2000

Increased endothelium--monocyte interactions in salt-sensitive hypertension: effect of L-arginine.

Although adhesion of monocytes to endothelial cells is considered as one of the initial factors leading in the long term to the development of atherosclerosis, the effects of hypertension on monocyte-endothelial cell interactions are still largely unknown. Thus we evaluated whether hypertension affects adhesion of monocytes on rat carotid endothelium, and whether this adhesion may be modified by long-term treatment with L-arginine, the physiologic precursor of nitric oxide (NO). Hypertension was induced in Dahl rats using a sodium-rich diet (8%), in the absence or the presence of L-arginine (1.25 g/L in drinking water). After 1 month, the carotid arteries were isolated, opened longitudinally, and incubated in the presence of 2 x 10(6) monocytes previously rendered fluorescent by incubation with tetramethyl rhodamine isothiocyanate (TRITC), and adherent cells were counted under fluorescence microscopy. In parallel, the production of NO was evaluated in vitro in isolated aorta and isolated hearts. Hypertension markedly increased adhesion of monocytes on carotid endothelium, and this was reduced by L-arginine. Hypertension also reduced an index of NO release at the level of the aorta and the coronary circulation. This impaired release of NO was partially prevented by L-arginine. Thus hypertension was associated with an increased adhesion of monocytes, which is probably due at least in part to a decreased production of NO. The increased adhesion was partly reduced by L-arginine, possibly secondary to an increased production of NO. Such an increased adhesion of monocytes may contribute the increased cardiovascular risk in hypertension.

Analysis of Variance↗
PubMed1999

Exercise improves flow-mediated vasodilatation of skeletal muscle arteries in rats with chronic heart failure. Role of nitric oxide, prostanoids, and oxidant stress.

BACKGROUND: Flow-mediated dilatation (FMD) of the peripheral arteries may be impaired in chronic heart failure (CHF), and this could contribute to the increased peripheral resistance and exercise intolerance that occur with this disease. Physical exercise improves the FMD of large conduit arteries in CHF, but whether a similar impairment also occurs in smaller arteries is unknown. The mechanisms of the changes in FMD after CHF or exercise are also unknown. METHODS AND RESULTS: FMD was assessed in isolated, perfused, and preconstricted gracilis muscle arteries from sham-operated rats or CHF rats (coronary artery ligation) who were either sedentary or exercised (30-minute swimming period twice a day for 10 weeks, starting 7 days after ligation). In animals with hemodynamic and echographic signs of CHF, FMD was abolished and converted into vasoconstriction (percent change in diameter after 370 microL/min flow: sham, 42+/-5%; CHF, -4+/-3%; P<0.05). Exercise partially restored FMD (18+/-3%; P<0.05 versus CHF). In sham rats, FMD was abolished by the nitric oxide-synthase inhibitor Nomega-nitro-L-arginine (L-NA) but unaffected by the cyclooxygenase inhibitor diclofenac or the free radical scavenger N-(2-mercaptopropionyl)-glycine (MPG). In arteries from sedentary CHF rats, FMD was not modified by L-NA, but it was partially restored by diclofenac or MPG. In exercised CHF rats, FMD was abolished by L-NA and only moderately improved by diclofenac or MPG. Likewise, endothelial nitric oxide synthase mRNA expression (determined by reverse transcription polymerase chain reaction at the level of the gracilis muscle) was reduced by CHF, and this was prevented by exercise. CONCLUSIONS: CHF abolishes the FMD of small arteries by impairing the nitric oxide pathway, increasing oxidant stress, and releasing a prostanoid-contracting factor. Exercise partially restores FMD by increasing expression of endothelial nitric oxide synthase and preventing the production of vasoconstrictor prostanoids and free radicals. Such restoration of FMD might contribute to the increase in exercise capacity after physical exercise in CHF.

Animals↗
PubMed1999

Molecular dissection of regulated secretory pathways in human gastric enterochromaffin-like cells: an immunohistochemical analysis.

Enterochromaffin-like (ECL) cells regulate gastric acid secretion through vesicular release of histamine. Until now, the molecular machinery of human ECL cells involved in the formation and release of vesicles is largely unknown. We analyzed tissue samples obtained from normal human gastric mucosa (n=4) and ECLomas (n=5) immunohistochemically using the APAAP method or double immunofluorescence confocal laser microscopy. Human pheochromocytomas (n=5) were investigated in parallel and compared to ECL cells. Secretory pathways were characterized using antibodies specific for marker proteins of large dense-core vesicles (LDCVs; islet cell antigen 512, chromogranin A, pancreastatin, and vesicular monoamine transporter 2) and small synaptic vesicle (SSV) analogues (synaptophysin). Tissues were also analyzed for expression of the peptide hormone processing enzymes, carboxypeptidase E and prohormone convertase 1, as well as the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins, 25-kDa synaptosome-associated protein (SNAP25), syntaxin, and synaptobrevin. Immunoreactivity for markers of LDCVs and SSV analogues were detected in normal ECL cells and ECLomas. Both tissues also showed expression of carboxypeptidase E and prohormone convertase 1. Analysis of vesicular SNARE (v-SNARE) and target membrane SNARE (t-SNARE) proteins revealed the presence of SNAP25, syntaxin, and synaptobrevin in normal and neoplastic ECL cells. Our data suggest that ECL cells possess the two vesicle types of regulated neuroendocrine secretory pathways, LDCVs and SSV analogues. Since ECL cells also contain typical SNARE proteins, the molecular machinery underlying secretory processes in this cell type appears to be identical to the secretory apparatus of neuroendocrine cells and neurons. In addition, our findings suggest that the secretory apparatus of ECL cells is maintained during neoplastic transformation.

Aspartic Acid Endopeptidases↗
PubMed1999

Presence of the vesicular inhibitory amino acid transporter in GABAergic and glycinergic synaptic terminal boutons.

The characterization of the Caenorhabditis elegans unc-47 gene recently allowed the identification of a mammalian (gamma)-amino butyric acid (GABA) transporter, presumed to be located in the synaptic vesicle membrane. In situ hybridization data in rat brain suggested that it might also take up glycine and thus represent a general Vesicular Inhibitory Amino Acid Transporter (VIAAT). In the present study, we have investigated the localization of VIAAT in neurons by using a polyclonal antibody raised against the hydrophilic N-terminal domain of the protein. Light microscopy and immunocytochemistry in primary cultures or tissue sections of the rat spinal cord revealed that VIAAT was localized in a subset (63-65%) of synaptophysin-immunoreactive terminal boutons; among the VIAAT-positive terminals around motoneuronal somata, 32.9% of them were also immunoreactive for GAD65, a marker of GABAergic presynaptic endings. Labelling was also found apposed to clusters positive for the glycine receptor or for its associated protein gephyrin. At the ultrastructural level, VIAAT immunoreactivity was restricted to presynaptic boutons exhibiting classical inhibitory features and, within the boutons, concentrated over synaptic vesicle clusters. Pre-embedding detection of VIAAT followed by post-embedding detection of GABA or glycine on serial sections of the spinal cord or cerebellar cortex indicated that VIAAT was present in glycine-, GABA- or GABA- and glycine-containing boutons. Taken together, these data further support the view of a common vesicular transporter for these two inhibitory transmitters, which would be responsible for their costorage in the same synaptic vesicle and subsequent corelease at mixed GABA-and-glycine synapses.

Amino Acid Transport Systems↗
PubMed1998

The isolated complex of the translocase of the outer membrane of mitochondria. Characterization of the cation-selective and voltage-gated preprotein-conducting pore.

The complex of the translocase mitochondrial outer membrane (TOM), mediates recognition, unfolding, and translocation of preproteins. We have used a combination of biochemical and electrophysiological methods to study the properties of the preprotein-conducting pore of the purified TOM complex. The pore is cation-selective and voltage-gated. It shows three main conductance levels with characteristic slow and fast kinetics transitions to states of lower conductance following application of transmembrane voltages. These electrical properties distinguish it from the mitochondrial voltage-dependent anion channel (porin) and are identical to those of the previously described peptide-sensitive channel. Binding of antibodies to the C terminus of Tom40 on the intermembrane space side of the outer membrane modifies the channel properties and allows determination of the orientation of the channel within the lipid bilayer. Mitochondrial presequence peptides specifically interact with the pore and decrease the ion flow through the channel in a voltage-dependent manner. We propose that the presequence-induced closures of the pore are related to structural alterations of the TOM complex observed during the various stages of preprotein movement across the mitochondrial outer membrane.

Biological Transport↗
PubMed1998

Increased UDP-glucuronosyltransferase activity and decreased prostate specific antigen production by biochanin A in prostate cancer cells.

Our laboratory has characterized androgen metabolism in an androgen-responsive prostate cancer cell line (LNCaP) and showed that these cells accumulated intracellular testosterone primarily as glucuronidated metabolites. Using a cell-free assay with testosterone as substrate, we showed that LNCaP had UDP-glucuronosyltransferase (UDPGT) activity. Because dietary factors, such as flavonoids in soy products, may reduce the risk for hormone-dependent cancers, we studied the effects of flavonoids on testosterone-UDPGT activity. LNCaP cells were exposed to selected flavonoids for up to 6 days. The increase in UDPGT-specific activity was linear over this period. Of the compounds tested, biochanin A was the most potent, with increased activity at concentration range 0.5-50 microM. Activities were linear for time and protein and were unaffected by flavonoids added directly to the assay. Kinetics studies showed no change in Km for testosterone in the face of these large increases in specific activity. Cellular metabolism of testosterone reflected the increase in enzyme activity. Intact cells treated with biochanin A produced testosterone-glucuronide from testosterone at twice the rate of controls. The steroid form of the UDPGT transcript was expressed in LNCaP cells and was enhanced in biochanin A-treated LNCaP cells. Additionally, biochanin A markedly decreased prostate specific antigen (PSA) level against the effect of testosterone on PSA production. Biochanin A significantly decreased the testosterone-stimulated release of PSA, presumably because biochanin A increased UDPGT and increased the intracellular glucuronidation of testosterone. These studies suggest that the modulation of hormone metabolism by dietary factors may be important in the prevention and treatment of prostate cancer.

Anticarcinogenic Agents↗
PubMed1998

Calcium-dependent regulation of rab3 in short-term plasticity.

The Rab3 proteins are monomeric GTP-binding proteins associated with secretory vesicles. In their active GTP-bound state, Rab3 proteins are involved in the regulation of hormone secretion and neurotransmitter release. This action is thought to involve specific effectors, including two Ca2+-binding proteins, Rabphilin and Rim. Rab3 acts late in the exocytotic process, in a cell domain in which the intracellular Ca2+ concentration is susceptible to rapid changes. Therefore, we examined the possible Ca2+-dependency of the regulatory action of GTP-bound Rab3 and wild-type Rab3 on neuroexocytosis at identified cholinergic synapses in Aplysia californica. The effects of recombinant GTPase-deficient Aplysia-Rab3 (apRab3-Q80L) or wild-type apRab3 were studied on evoked acetylcholine release. Intraneuronal application of apRab3-Q80L in identified neurons of the buccal ganglion of Aplysia led to inhibition of neurotransmission; wild-type apRab3 was less effective. Intracellular chelation of Ca2+ ions by EGTA greatly potentiated the inhibitory action of apRab3-Q80L. Train and paired-pulse facilitation, two Ca2+-dependent forms of short-term plasticity induced by a rise in intraterminal Ca2+ concentration, were increased after injection of apRab3-Q80L. This result suggests that the inhibition exerted by GTP-bound Rab3 on neuroexocytosis is reduced during transient augmentations of intracellular Ca2+ concentration. Therefore, a Ca2+-dependent modulation of GTP-bound Rab3 function may contribute to short-term plasticity.

Acetylcholine↗
PubMed1998

The vesicular monoamine transporter: from chromaffin granule to brain.

All characterized monoaminergic cells utilize the same transport system for the vesicular accumulation of monoamines prior to their release. This system operates in neuronal (catecholaminergic, serotoninergic or histaminergic) as well as in endocrine or neuroendocrine cells. For several decades, chromaffin granules from bovine adrenal medulla have been used as a model system, allowing progress in the understanding of the biophysics, the biochemistry and the pharmacology of the monoamine vesicular transporter. The transporters from rat, bovine and man have been cloned. Surprisingly, two genes encode different isoforms of the protein which are differentially expressed in monoaminergic systems. The conjunction of recombinant DNA techniques and expression in secretory or non-secretory cells with the large body of data obtained on the chromaffin granule transporter has allowed rapid progress in the study of the protein. But interestingly enough, this progress has open new possibilities in the study of biological problems, especially in the brain. The transporter is useful for the determination of the relationship between small and large dense core vesicles, for the understanding of the mechanism of the drugs such as 1-methyl-4-phenylpyridinium (MPP+), tetrabenazine or amphetamines, and as a marker in brain development. The possibility of regulations at the vesicular transporter level and of their effect on the quantum size has to be investigated. The vesicular monoamine transporter is also an important target for brain imaging.

Amino Acid Sequence↗
PubMed1998

Effects of early stress on adult affiliative behavior.

The recently evolved mammalian species preservative behavior as opposed to the ancient self preservative behavior involves parental care, nursing, social interaction, pair bonding and mutual defense. Gonadal steroids together with oxytocin are critical for this affiliative, attachment behavior. When there is stressful loss of control, gonadotrophins are diminished, and the self preservative, fight-flight catecholamine coping response takes priority. It is suggested that self preservation is associated with left hemispheric brain function and that species preservation is associated with right hemispheric function. Stress during infancy that is severe enough to create insecure attachment has a dissociative effect, disrupting right hemispheric emotional functioning and species preservative behavior, and a permanent bias towards self preservation can become an adult trait. In such a person with impaired affiliation, corticoid responses may be deficient. The coronary type A behavior pattern common in our society exhibits some of this deficiency in species preservative activity.

Animals↗
PubMed1998

Regulation of the Ca2+ sensitivity of exocytosis by Rab3a.

Ca2+ ions trigger the release of hormones and neurotransmitters and contribute to making the secretory vesicles competent for fusion. Here, we present evidence for the involvement of the GTP-binding protein Rab3a in the sensitivity of the exocytotic process to internal [Ca2+]. The secretory activity of bovine adrenal chromaffin cells was elicited by Ca2+ dialysis through a patch-clamp pipette and assayed by monitoring changes in cell membrane capacitance. Microinjection of antisense oligonucleotides directed to rab3a mRNA increased the secretory activity observed at low (0.2-4 microM) [Ca2+], but did not change the maximal activity observed at 10 microM free [Ca2+]. Moreover, after a train of depolarizing stimuli, the secretory activity of antisense-injected cells dialyzed with 10 microM [Ca2+] was increased significantly compared with that of control cells. This result suggests that the activity of either Rab3a or its partners might change upon stimulation. We conclude that Rab3a, together with its partners, participates in the Ca2+ dependence of exocytosis and that its activity is modulated further in a stimulus-dependent manner. These findings should provide some clues to elucidate the role of Rab3a in synaptic plasticity.

Adrenal Glands↗
PubMed1997

Cloning of a functional vesicular GABA and glycine transporter by screening of genome databases.

The unc-47 locus of Caenorhabditis elegans has been suggested to encode a synaptic vesicle GABA transporter. Here we used hydropathy plot analysis to identify a candidate vesicular GABA transporter in genomic sequences derived from a region of the physical map comprising unc-47. A mouse homologue was identified and cloned from EST database information. In situ hybridization in rat brain revealed codistribution with both GABAergic and glycinergic neuronal markers. Moreover, expression in COS-7 and PC12 cells induced an intracellular, glycine-sensitive GABA uptake activity. These observations, consistent with previous data on GABA and glycine uptake by synaptic vesicles, demonstrate that the mouse clone encodes a vesicular inhibitory amino acid transporter.

Amino Acid Sequence↗
PubMed1997

Role of endogenous endothelin in chronic heart failure: effect of long-term treatment with an endothelin antagonist on survival, hemodynamics, and cardiac remodeling.

BACKGROUND: Plasma levels of the vasoconstrictor peptide endothelin (ET) are increased in chronic heart failure (CHF), and ET levels are a major predictor of mortality in this disease. Thus, ET may play a deleterious role in CHF. The purpose of this study was to assess the effects of chronic treatment with the ET receptor antagonist bosentan in a rat model of CHF. METHODS AND RESULTS: Rats were subjected to coronary artery ligation and were treated for 2 or 9 months with placebo or bosentan (30 or 100 mg x kg(-1) x d(-1)). Bosentan 100 mg x kg(-1) markedly increased survival (after 9 months: untreated, 47%; bosentan, 65%; P<.01). Throughout the 9-month treatment period, bosentan significantly reduced arterial pressure and heart rate. After 2 or 9 months of treatment, the ET antagonist reduced central venous pressure and left ventricular (LV) end-diastolic pressure as well as plasma catecholamines, urinary cGMP, and LV ventricular collagen density. Bosentan also reduced LV dilatation (evidenced at 2 months by a shift in the pressure/volume relationship ex vivo). Echocardiographic studies performed after 2 months showed that the ET antagonist reduced hypertrophy and increased contractility of the noninfarcted LV wall. The lower dose of bosentan (30 mg x kg(-1)), which had no major hemodynamic or structural effects, also had no effect on survival. CONCLUSIONS: Long-term treatment with an ET antagonist markedly increases survival in this rat model of CHF. This increase in survival is associated with decreases in both preload and afterload and an increase in cardiac output as well as decreased LV hypertrophy, LV dilatation, and cardiac fibrosis. Thus, chronic treatment with ET antagonists such as bosentan might be beneficial in human CHF and might increase long-term survival in this disease.

Animals↗
PubMed1997

Translocation of cytosolic annexin 2 to a Triton-insoluble membrane subdomain upon nicotine stimulation of chromaffin cultured cells.

To gain a better understanding of the function of annexin 2, we have investigated the subcellular distribution of the monomeric and heterotetrameric forms of annexin 2 and their relationship to the cytoskeleton upon stimulation of chromaffin cells. Quantitative immunoblotting has revealed that in resting cells a large amount of annexin 2 is monomeric and cytosolic. Upon nicotine stimulation 80% of total annexin 2 becomes associated with a Triton-X100-insoluble fraction where the monomeric and the heterotetrameric forms are found. The translocation of monomeric annexin 2 is Ca2+-dependent and complete at 1 microM free Ca2+. We have shown that about 66% of the annexin 2 associated with the Triton-X100-insoluble fraction is soluble in octylglucoside while the remnants are insoluble in the detergent and remain likely associated with actin filaments and associated cytoskeleton proteins. The octylglucoside-soluble fraction contains integral proteins from the plasma membrane and from granule membrane, but does not contain caveolin. Moreover, upon nicotine stimulation, a redistribution of proteins was detected in this fraction. These dynamic processes appear concomitantly with the phosphorylation of annexin 2 in this compartment and with catecholamine release. It is suggested that the soluble octylglucoside fraction may represent a special lipidic membrane compartment where the NSF attachment proteins and the cytosolic proteins like annexin 2 and rab3a may become concentrated upon stimulation of the cell. The presence of annexin 2 is consistent with its proposed function on granule and target membrane proteins required for the close apposition of two distinct membranes and supports its functional role in the regulated exocytosis/endocytosis process.

Animals↗
PubMed1997

The photoactivatable inhibitor 7-azido-8-iodoketanserin labels the N terminus of the vesicular monoamine transporter from bovine chromaffin granules.

In monoaminergic cells, the hormone or neurotransmitter is concentrated into secretory vesicles by a tetrabenazine- and reserpine-sensitive vesicular monoamine transporter (VMAT), catalyzing a H+/monoamine antiport. Ketanserin is another powerful inhibitor of VMAT that binds to the tetrabenazine binding site. A photoactivatable derivative, 7-azido-8-iodoketanserin (AZIK), labels covalently the transporter from bovine chromaffin granules, VMAT-2. Digestion with endoproteinases V8 or Lys-C, which cleave peptide bonds at acidic or lysine residues, respectively, revealed that the AZIK label is located in a 7 kDa segment of the VMAT-2 polypeptide. The photolabeled chromaffin granule transporter was purified by DEAE and WGA chromatography followed by selective aggregation and size-exclusion HPLC. After treatment by V8 or Lys-C, digestion products were separated by electrophoresis in SDS and sequenced. For both enzymes, the material comigrating with the labeled peptide produced a sequence matching the N terminus of VMAT-2. A K55E mutant of the bovine VMAT-2 cDNA was constructed and expressed in COS-7 cells. The mutant protein exhibited a full VMAT activity and could be labeled by AZIK. However, the formation of the 7 kDa labeled peptide upon Lys-C proteolysis was prevented in the mutant, with a redistribution of the label in higher-molecular mass digestion products. The localization of the label upstream of lysine 55 was confirmed by an immunological and enzymatic analysis. We conclude that the segment 2-55 of bovine VMAT-2, which encompasses the cytosolic N terminus and the first transmembrane segment in the current topological model of the transporter, contains residues involved in the binding of ketanserin and, possibly, tetrabenazine.

Adrenal Medulla↗
PubMed1997

Early versus delayed angiotensin-converting enzyme inhibition in experimental chronic heart failure. Effects on survival, hemodynamics, and cardiovascular remodeling.

BACKGROUND: The efficacy of ACE inhibitors in congestive heart failure (CHF) might be affected by the pathophysiological status present at the onset of treatment. We compared in a rat model the effects of ACE inhibition (lisinopril, 10 mg.kg-1.d-1) initiated early (1 week) or late (3 months) after myocardial infarction (i.e., at time points corresponding to moderate or severe CHF without or with established cardiac remodeling). METHODS AND RESULTS: Survival was improved by early treatment at 3 months (from 76% to 95%) and by both early and delayed treatment at 9 months (placebo, 28%; early, 90%; delayed, 61%). Delayed treatment was initiated in a more severe pathophysiological context of CHF than early treatment, illustrated in untreated rats by higher left ventricular (LV) end-diastolic and central venous pressures and by increased LV weight and LV cavity circumference. After 9 months, early and delayed treatments reduced systolic, LV end-diastolic, and central venous pressures. Both treatments also similarly decreased LV weight, LV cavity circumference, and LV collagen density. CONCLUSIONS: In this rat model of CHF, early and delayed ACE inhibitor treatments both increase survival and exert similar beneficial effects on cardiac hemodynamics and remodeling. Although early treatment prevents the development of ventricular dysfunction and remodeling, delayed treatment is capable of reversing cardiac hypertrophy and remodeling, as well as ventricular dysfunction. Thus, ACE inhibitors exert marked beneficial effects even when treatment is initiated late into the evolution of heart failure (ie, at a time of established ventricular dysfunction and remodeling).

Analysis of Variance↗