Papers by Jean-pièrre Timmermans
Polish journal of veterinary sciences, 2004
The present study investigated the chemical coding of neurons in the celiac-superior mesenteric g... more The present study investigated the chemical coding of neurons in the celiac-superior mesenteric ganglion complex supplying the normal (n=4) and inflamed (n=4) ileum (chemically-induced inflammation) in juvenile pigs using retrograde tracing combined with immunohistochemistry. Ileum-projecting neurons (IPN) were predominantly distributed in the left and right superior mesenteric pools of the ganglion. The majority of them were adrenergic (tyrosine hydroxylase-positive) and also contained neuropeptide Y, somatostatin or galanin. No clear-cut differences in the distribution and chemical coding of IPN were found between normal and inflamed pigs. However, in the inflamed group, the density of peptidergic, IPN-associated nerve fibres was higher than that found in the control group.
Journal of Clinical Investigation, 2007
This study illustrates that Plekhm1 is an essential protein for bone resorption, as loss-of-funct... more This study illustrates that Plekhm1 is an essential protein for bone resorption, as loss-of-function mutations were found to underlie the osteopetrotic phenotype of the incisors absent rat as well as an intermediate type of human osteopetrosis. Electron and confocal microscopic analysis demonstrated that monocytes from a patient homozygous for the mutation differentiated into osteoclasts normally, but when cultured on dentine discs, the osteoclasts failed to form ruffled borders and showed little evidence of bone resorption. The presence of both RUN and pleckstrin homology domains suggests that Plekhm1 may be linked to small GTPase signaling. We found that Plekhm1 colocalized with Rab7 to late endosomal/lysosomal vesicles in HEK293 and osteoclast-like cells, an effect that was dependent on the prenylation of Rab7. In conclusion, we believe PLEKHM1 to be a novel gene implicated in the development of osteopetrosis, with a putative critical function in vesicular transport in the osteoclast. Nonstandard abbreviations used: EGFP, enhanced GFP; GGTase, geranylgeranyl transferase; ia, incisors absent; PH, pleckstrin homology; PLEKHM1, pleckstrin homology domain-containing family M (with RUN domain) member 1; TRAP, tartrateresistant acid phosphatase; TRITC, tetramethylrhodamine isothiocyanate; VNR, vitronectin receptor.
Electrically silent voltage-gated potassium (KvS) channel subunits (i.e. Kv5–Kv6 and Kv8–Kv9) do ... more Electrically silent voltage-gated potassium (KvS) channel subunits (i.e. Kv5–Kv6 and Kv8–Kv9) do not form functional homotetrameric Kv channels, but co-assemble with Kv2 subunits, generating functional heterotetrameric Kv2–KvS channel complexes in which the KvS subunits modulate the Kv2 channel properties. Several KvS subunits are expressed in testis tissue but knowledge about their contribution to testis physiology is lacking. Here, we report that the targeted deletion of Kv6.4 in a transgenic mouse model (Kcng4 À/À) causes male sterility as offspring from homozygous females were only obtained after mating with wild-type (WT) or heterozygous males. Semen quality analysis revealed that the sterility of the homozygous males was caused by a severe reduction in total sperm-cell count and the absence of motile spermatozoa in the semen. Furthermore, spermatozoa of homozygous mice showed an abnormal morphology char-acterised by a smaller head and a shorter tail compared with WT spermatozoa. Comparison of WT and Kcng4 À/À testicular tissue indicated that this inability to produce (normal) spermatozoa was due to disturbed spermiogenesis. These results suggest that Kv6.4 subunits are involved in the regulation of the late stages of spermatogenesis, which makes them a potentially interesting pharmacological target for the development of non-hormonal male contraceptives.
Circulation, 2008
Background-The B vitamin folic acid (FA) is important to mitochondrial protein and nucleic acid s... more Background-The B vitamin folic acid (FA) is important to mitochondrial protein and nucleic acid synthesis, is an antioxidant, and enhances nitric oxide synthase activity. Here, we tested whether FA reduces myocardial ischemic dysfunction and postreperfusion injury.
Catheterization and Cardiovascular Interventions, 2013
Aim: To evaluate differences in strut coverage, inflammation and endothelialization between two s... more Aim: To evaluate differences in strut coverage, inflammation and endothelialization between two second-generation polymer-based drug-eluting stents (DES) in an atherosclerotic rabbit double-injury iliac artery model at 28 days follow-up. Methods and results: Rabbits with induced atheroma received bilateral iliac artery stents: everolimus-eluting stent (Xience V EES; Abbott Vascular), zotarolimus-eluting stent (Resolute ZES; Medtronic CardioVascular), or bare-metal stent (BMS; MultiLink Vision; Abbott Vascular). After 28 days, total neointimal coverage examined by scanning electron microscopy was >98% for all three stent types. Neointimal thickness above stent struts was decreased by 50% in Xience V EES (0.06 6 0.01 mm; P 5 0.00001) compared with BMS (0.15 6 0.03 mm) and Resolute ZES (0.12 6 0.04 mm). Luminal area was largest for Xience V EES (3.79 6 0.33 mm 2 ; P 5 0.0003 for Xience V EES vs. BMS), followed by Resolute ZES (3.46 6 0.45 mm 2 ; P 5 0.083 for Resolute ZES vs. BMS) and BMS (3.07 6 0.53 mm 2 ). Percentage area stenosis was smallest for Xience V EES (17.23 6 3.64%; P 5 0.00001), while BMS (30.25 6 7.48%) and Resolute ZES (30.79 6 7.15%) did not differ. Endothelial monolayer regrowth was significantly lower in Resolute ZES (65 6 13%) versus BMS (79 6 11%; P 5 0.004). There was no difference between Xience V EES (74 6 10%) and BMS. Xience V EES was further associated with a lower number of inflammatory cells surrounding the stent struts (7 6 2 per strut) in comparison to Resolute ZES (15 6 6; P 5 0.0001) and BMS (17 6 9; P 5 0.0005). Conclusion: In this atherosclerotic rabbit model, Xience V EES suppressed neointimal thickening better, with normal endothelial regrowth as compared with BMS, and less strutinduced inflammation. V C 2012 Wiley Periodicals, Inc.
Acta Ophthalmologica, 2013
To determine if a standardized, non-xenogenic, reduced manipulation cultivation and surgical tran... more To determine if a standardized, non-xenogenic, reduced manipulation cultivation and surgical transplantation of limbal stem cell grafts is a safe and effective treatment option for patients with total and partial limbal stem cell deficiency. Methods: In vitro cellular outgrowth and phenotype of the limbal epithelial cell and composite grafts were validated using a new protocol. Patients received either autologous (n = 15) or allogenic (n = 3) explants cultured using a standardized protocol free from xenogenic products. The resulting grafts were transplanted using a reduced manipulation surgical technique.
Cell & Tissue Research, 1994
We have investigated indirectly the presence of nitric oxide in the enteric nervous system of the... more We have investigated indirectly the presence of nitric oxide in the enteric nervous system of the digestive tract of human fetuses and newborns by nitric oxide synthase (NOS) immunocytochemistry and nicotinamide adenine dinucleotide phosphate diaphorase (NADPHd) histochemistry. In the stomach, NOS immunoactivity was confined to the myenteric plexus and nerve fibres in the outer smooth musculature; few immunoreactive nerve cell bodies were found in ganglia of the outer submucous plexus. In the pyloric region, a few nitrergic perikarya were seen in the inner submucous plexus and some immunoreactive fibres were found in the muscularis mucosae. In the small intestine, nitrergic neurons clustered just underneath or above the topographical plane formed by the primary nerve strands of the myenteric plexus up to the 26th week of gestation, after which stage, they occurred throughout the ganglia. Many of their processes contributed to the dense fine-meshed tertiary nerve network of the myenteric plexus and the circular smooth muscle layer. NOS-immunoreactive fibres directed to the circular smooth muscle layer originated from a few NOScontaining perikarya located in the outer submucous plexus. In the colon, caecum and rectum, labelled nerve cells and fibres were numerous in the myenteric plexus; they were also found in the outer submucous plexus. The circular muscle layer had a much denser NOS-immunoreactive innervation than the longitudinally oriented taenia. The marked morphological differences observed between nitrergic neurons within the developing human gastrointestinal tract, together with the typical innervation pattern in the ganglionic and aganglionic nerve networks, support the existenc of distinct subpopulations of NOS-containing enterice neurons acting as interneurons or (inhibitory) motor neurons.
Nature Genetics, 2006
Charcot-Marie-Tooth (CMT) neuropathies are common disorders of the peripheral nervous system caus... more Charcot-Marie-Tooth (CMT) neuropathies are common disorders of the peripheral nervous system caused by demyelination or axonal degeneration, or a combination of both features. We previously assigned the locus for autosomal dominant intermediate CMT neuropathy type C (DI-CMTC) to chromosome 1p34-p35. Here we identify two heterozygous missense mutations (G41R and E196K) and one de novo deletion (153-156delVKQV) in tyrosyl-tRNA synthetase (YARS) in three unrelated families affected with DI-CMTC. Biochemical experiments and genetic complementation in yeast show partial loss of aminoacylation activity of the mutant proteins, and mutations in YARS, or in its yeast ortholog TYS1, reduce yeast growth. YARS localizes to axonal termini in differentiating primary motor neuron and neuroblastoma cultures. This specific distribution is significantly reduced in cells expressing mutant YARS proteins. YARS is the second aminoacyl-tRNA synthetase found to be involved in CMT, thereby linking protein-synthesizing complexes with neurodegeneration.
Autonomic Neuroscience, 2009
Sox10-IR in greater proportions compared with TH-IR. The proportion of Sox10-IR cells had increas... more Sox10-IR in greater proportions compared with TH-IR. The proportion of Sox10-IR cells had increased to 31% of all cells in the ganglion.
Human Molecular Genetics, 2010
Missense mutations (K141N and K141E) in the a-crystallin domain of the small heat shock protein H... more Missense mutations (K141N and K141E) in the a-crystallin domain of the small heat shock protein HSPB8 (HSP22) cause distal hereditary motor neuropathy (distal HMN) or Charcot-Marie-Tooth neuropathy type 2L (CMT2L). The mechanism through which mutant HSPB8 leads to a specific motor neuron disease phenotype is currently unknown. To address this question, we compared the effect of mutant HSPB8 in primary neuronal and glial cell cultures. In motor neurons, expression of both HSPB8 K141N and K141E mutations clearly resulted in neurite degeneration, as manifested by a reduction in number of neurites per cell, as well as in a reduction in average length of the neurites. Furthermore, expression of the K141E (and to a lesser extent, K141N) mutation also induced spheroids in the neurites. We did not detect any signs of apoptosis in motor neurons, showing that mutant HSPB8 resulted in neurite degeneration without inducing neuronal death. While overt in motor neurons, these phenotypes were only very mildly present in sensory neurons and completely absent in cortical neurons. Also glial cells did not show an altered phenotype upon expression of mutant HSPB8. These findings show that despite the ubiquitous presence of HSPB8, only motor neurons appear to be affected by the K141N and K141E mutations which explain the predominant motor neuron phenotype in distal HMN and CMT2L.
Polish journal of veterinary sciences, 2004
The present study investigated the chemical coding of neurons in the celiac-superior mesenteric g... more The present study investigated the chemical coding of neurons in the celiac-superior mesenteric ganglion complex supplying the normal (n=4) and inflamed (n=4) ileum (chemically-induced inflammation) in juvenile pigs using retrograde tracing combined with immunohistochemistry. Ileum-projecting neurons (IPN) were predominantly distributed in the left and right superior mesenteric pools of the ganglion. The majority of them were adrenergic (tyrosine hydroxylase-positive) and also contained neuropeptide Y, somatostatin or galanin. No clear-cut differences in the distribution and chemical coding of IPN were found between normal and inflamed pigs. However, in the inflamed group, the density of peptidergic, IPN-associated nerve fibres was higher than that found in the control group.
World journal of gastrointestinal pharmacology and therapeutics, Jan 6, 2015
To study the effect of the opioid-receptor like-1 (ORL1) agonist nociceptin on gastrointestinal (... more To study the effect of the opioid-receptor like-1 (ORL1) agonist nociceptin on gastrointestinal (GI) myenteric neurotransmission and motility. Reverse transcriptase - polymerase chain reaction and immunohistochemistry were used to localize nociceptin and ORL1 in mouse tissues. Intracellular electrophysiological recordings of excitatory and inhibitory junction potentials (EJP, IJP) were made in a chambered organ bath. Intestinal motility was measured in vivo. Nociceptin accelerated whole and upper GI transit, but slowed colonic expulsion in vivo in an ORL1-dependent manner, as shown using [Nphe(1)]NOC and AS ODN pretreatment. ORL1 and nociceptin immunoreactivity were found on enteric neurons. Nociceptin reduced the EJP and the nitric oxide-sensitive slow IJP in an ORL1-dependent manner, whereas the fast IJP was unchanged. Nociceptin further reduced the spatial spreading of the EJP up to 2 cm. Compounds acting at ORL1 are good candidates for the future treatment of disorders associate...
Obesity Facts, 2010
SummaryObjective: Melanocortin-4 receptor (MC4R) deficiency is the most common cause of monogenic... more SummaryObjective: Melanocortin-4 receptor (MC4R) deficiency is the most common cause of monogenic obesity. In the present study, we screened the MC4R gene for mutations in a population of overweight and obese children and adolescents. Method: Cross-sectional mutation analysis of 112 overweight/obese children and adolescents and 121 lean individuals. Results: We identified 11 sequence variations, 5 of which were present in
Pulmonary neuroepithelial bodies (NEBs), occurring as densely innervated groups of neuroendocrine... more Pulmonary neuroepithelial bodies (NEBs), occurring as densely innervated groups of neuroendocrine cells in the airway epithelium, were recently suggested to act as complex sensory airway receptors. Despite the considerable amount of morphological and neurochemical data, none of the functional hypotheses has so far been fully established. Physiological studies are hampered by the relatively small number and dispersed distribution of NEBs
Today, diagnosis and treatment of chest pain related to pathologic changes in the visceral pleura... more Today, diagnosis and treatment of chest pain related to pathologic changes in the visceral pleura are often difficult. Data in the literature on the sensory innervation of the visceral pleura are sparse. The present study aimed at identifying sensory end-organs in the visceral pleura, and at obtaining more information about neurochemical coding. The immunocytochemcial data are mainly based on whole mounts of the visceral pleura of control and vagally denervated rats. It was shown that innervation of the rat visceral pleura is characterized by nerve bundles that enter in the hilus region and gradually split into slender bundles with a few nerve fibers. Separate nerve fibers regularly give rise to characteristic laminar terminals. Because of their unique association with the elastic fibers of the visceral pleura, we decided to refer to them as "visceral pleura receptors" (VPRs). Cryostat sections of rat lungs confirmed a predominant location on mediastinal and interlobar lung surfaces. VPRs can specifically be visualized by protein gene product 9.5 immunostaining, and were shown to express vesicular glutamate transporters, calbindin D28K, Na+/K+-ATPase, and P2X3 ATP-receptors. The sensory nerve fibers giving rise to VPRs appeared to be myelinated and to have a spinal origin. Because several of the investigated proteins have been reported as markers for sensory terminals in other organs, the present study revealed that VPRs display the neurochemical characteristics of mechanosensory and/or nociceptive terminals. The development of a live staining method, using AM1-43, showed that VPRs can be visualized in living tissue, offering an interesting model for future physiologic studies.
The Fawn-Hooded rat (FHR), a model for primary pulmonary hypertension, shows an unexplained hyper... more The Fawn-Hooded rat (FHR), a model for primary pulmonary hypertension, shows an unexplained hypersensitivity to airway hypoxia. Because pulmonary neuroepithelial bodies (NEBs) ap- pear to express a functional oxygen-sensing mechanism and an extensive sensory innervation, possible changes in this system should be taken into consideration. In the present study a com- parative analysis of NEBs and their selective innervation was
Today, diagnosis and treatment of chest pain related to pathologic changes in the visceral pleura... more Today, diagnosis and treatment of chest pain related to pathologic changes in the visceral pleura are often difficult. Data in the litera- ture on the sensory innervation of the visceral pleura are sparse. The present study aimed at identifying sensory end-organs in the visceral pleura, and at obtaining more information about neuro- chemical coding. The immunocytochemcial data are mainly based
International journal of developmental neuroscience : the official journal of the International Society for Developmental Neuroscience, 2015
Expression of vasoactive intestinal peptide (VIP), neuronal nitric oxide synthase (nNOS), choline... more Expression of vasoactive intestinal peptide (VIP), neuronal nitric oxide synthase (nNOS), choline acetyltransferase (ChAT) and calcitonin gene-related peptide (CGRP) in the sympathetic ganglia was investigated by immunohistochemistry in the superior cervical ganglion (SCG), stellate ganglion (SG) and celiac ganglion (CG) from cats of different ages (newborn, 10-day-old, 20-day-old, 30-day-old and 2-month-old). Non-catecholaminergic TH-negative VIP-immunoreactive (IR) and nNOS-IR sympathetic ganglionic neurons are present from the moment of birth. In all studied age groups, substantial populations of VIP-IR (up to 9.8%) and nNOS-IR cells (up to 8.3%) was found in the SG, with a much smaller population found in the SCG (<1%) and only few cells observed in the CG. The percentage of nNOS-IR and VIP-IR neurons in the CG and SCG did not significantly change during development. The proportion of nNOS-IR and VIP-IR neuron profiles in the SG increased in first 20 days of life from 2.3±0.1...
Anatomical record. Part B, New anatomist, 2005
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Papers by Jean-pièrre Timmermans