Deficiency of Endogenous Acute-Phase Serum Amyloid A Protects apoE-/- Mice From Angiotensin II-Induced Abdominal Aortic Aneurysm Formation

OBJECTIVE

Rupture of abdominal aortic aneurysm (AAA), a major cause of death in the aged population, is characterized by vascular inflammation and matrix degradation. Serum amyloid A (SAA), an acute-phase reactant linked to inflammation and matrix metalloproteinase induction, correlates with aortic dimensions before aneurysm formation in humans. We investigated whether SAA deficiency in mice affects AAA formation during angiotensin II (Ang II) infusion.

APPROACH AND RESULTS

Plasma SAA increased ≈60-fold in apoE(-/-) mice 24 hours after intraperitoneal Ang II injection (100 μg/kg; n=4) and ≈15-fold after chronic 28-day Ang II infusion (1000 ng/kg per minute; n=9). AAA incidence and severity after 28-day Ang II infusion was significantly reduced in apoE(-/-) mice lacking both acute-phase SAA isoforms (SAAKO; n=20) compared with apoE(-/-) mice (SAAWT; n=20) as assessed by in vivo ultrasound and ex vivo morphometric analyses, despite a significant increase in systolic blood pressure in SAAKO mice compared with SAAWT mice after Ang II infusion. Atherosclerotic lesion area of the aortic arch was similar in SAAKO and SAAWT mice after 28-day Ang II infusion. Immunostaining detected SAA in AAA tissues of Ang II-infused SAAWT mice that colocalized with macrophages, elastin breaks, and enhanced matrix metalloproteinase activity. Matrix metalloproteinase-2 activity was significantly lower in aortas of SAAKO mice compared with SAAWT mice after 10-day Ang II infusion.

CONCLUSIONS

Lack of endogenous acute-phase SAA protects against experimental AAA through a mechanism that may involve reduced matrix metalloproteinase-2 activity.

Abstract 64: Serum Amyloid A Augments Angiotensin II-Induced Abdominal Aortic Aneurysm Formation in ApoE-Deficient Mice

Introduction and Objectives: Abdominal aortic aneurysm (AAA), a major cause of death in the aged population, is characterized by vascular inflammation and matrix degradation. Proteolytic enzymes, particularly matrix metalloproteinases (MMP’s), are hypothesized to be active participants in AAA pathogenesis. Serum amyloid A (SAA) is an acute phase reactant that, unlike C-reactive protein (CRP), correlates in humans with aortic dimensions before aneurysm formation. SAA induces MMP expression in cultured cells. In this study we determined whether SAA deficiency in mice altered AAA formation in the well-established angiotensin II (Ang II) infusion model.

Methods and Results: We confirmed that SAA induced MMP-9 and MMP-13 mRNA abundance in J774 macrophage-like cells. Furthermore, we determined for the first time that SAA enhanced MMP-2 activity in cultured mouse abdominal aorta explants. Plasma SAA increased ∼400-fold in apoE -/- mice 24 hours after i.p. Ang II injection (100μg/kg) and ∼12-fold after 28-day Ang II infusion (1000ng/kg/hour). SAA was detected by immunostaining in human AAA tissues and in AAAs of AngII-infused apoE -/- mice. Based on in vivo ultrasound and ex vivo morphological analyses, apoE -/- mice with targeted deletion of SAA (SAAKO; n = 20) exhibited significantly reduced AAA 28 days after Ang II infusion compared to apoE -/- mice that were wild type for SAA (SAAWT; n = 20), despite a modest, but significant increase in the hypertensive response to Ang II. Although the incidence of aortic rupture in SAAKO mice (15%) and SAAWT mice (20%) were similar, the majority of ruptures (75%) in SAAWT mice occurred in the abdominal region, whereas all of the ruptures in the SAAKO mice occurred in the thoracic region. Atherosclerotic lesion area on the luminal surface of the aortic arch was similar in SAAKO and SAAWT mice after Ang II infusion.

Conclusion: Our finding that SAA plays a role in experimental AAA may be pertinent to human studies correlating indexed aortic diameter with plasma SAA concentrations.

DICER1 deficit induces Alu RNA toxicity in age-related macular degeneration

Geographic atrophy (GA), an untreatable advanced form of age-related macular degeneration, results from retinal pigmented epithelium (RPE) cell degeneration. Here we show that the microRNA (miRNA)-processing enzyme DICER1 is reduced in the RPE of humans with GA, and that conditional ablation of Dicer1, but not seven other miRNA-processing enzymes, induces RPE degeneration in mice. DICER1 knockdown induces accumulation of Alu RNA in human RPE cells and Alu-like B1 and B2 RNAs in mouse RPE. Alu RNA is increased in the RPE of humans with GA, and this pathogenic RNA induces human RPE cytotoxicity and RPE degeneration in mice. Antisense oligonucleotides targeting Alu/B1/B2 RNAs prevent DICER1 depletion-induced RPE degeneration despite global miRNA downregulation. DICER1 degrades Alu RNA, and this digested Alu RNA cannot induce RPE degeneration in mice. These findings reveal a miRNA-independent cell survival function for DICER1 involving retrotransposon transcript degradation, show that Alu RNA can directly cause human pathology, and identify new targets for a major cause of blindness.

Intestinal epithelial serum amyloid A modulates bacterial growth in vitro and pro-inflammatory responses in mouse experimental colitis

BACKGROUND

Serum Amyloid A (SAA) is a major acute phase protein of unknown function. SAA is mostly expressed in the liver, but also in other tissues including the intestinal epithelium. SAA reportedly has anti-bacterial effects, and because inflammatory bowel diseases (IBD) result from a breakdown in homeostatic interactions between intestinal epithelia and bacteria, we hypothesized that SAA is protective during experimental colitis.

METHODS

Intestinal SAA expression was measured in mouse and human samples. Dextran sodium sulfate (DSS) colitis was induced in SAA 1/2 double knockout (DKO) mice and in wildtype controls. Anti-bacterial effects of SAA1/2 were tested in intestinal epithelial cell lines transduced with adenoviral vectors encoding the CE/J SAA isoform or control vectors prior to exposure to live Escherichia coli.

RESULTS

Significant levels of SAA1/SAA2 RNA and SAA protein were detected by in situ hybridization and immunohistochemistry in mouse colonic epithelium. SAA3 expression was weaker, but similarly distributed. SAA1/2 RNA was present in the ileum and colon of conventional mice and in the colon of germfree mice. Expression of SAA3 was strongly regulated by bacterial lipopolysaccharides in cultured epithelial cell lines, whereas SAA1/2 expression was constitutive and not LPS inducible. Overexpression of SAA1/2 in cultured epithelial cell lines reduced the viability of co-cultured E. coli. This might partially explain the observed increase in susceptibility of DKO mice to DSS colitis. SAA1/2 expression was increased in colon samples obtained from Crohn's Disease patients compared to controls.

CONCLUSIONS

Intestinal epithelial SAA displays bactericidal properties in vitro and could play a protective role in experimental mouse colitis. Altered expression of SAA in intestinal biopsies from Crohn's Disease patients suggests that SAA is involved in the disease process..

Chylomicrons promote intestinal absorption of lipopolysaccharides

Recent data suggest that dietary fat promotes intestinal absorption of lipopolysaccharides (LPS) from the gut microflora, which might contribute to various inflammatory disorders. The mechanism of fat-induced LPS absorption is unclear, however. Intestinal-epithelial cells can internalize LPS from the apical surface and transport LPS to the Golgi. The Golgi complex also contains newly formed chylomicrons, the lipoproteins that transport dietary long-chain fat through mesenteric lymph and blood. Because LPS has affinity for chylomicrons, we hypothesized that chylomicron formation promotes LPS absorption. In agreement with our hypothesis, we found that CaCo-2 cells released more cell-associated LPS after incubation with oleic-acid (OA), a long-chain fatty acid that induces chylomicron formation, than with butyric acid (BA), a short-chain fatty acid that does not induce chylomicron formation. Moreover, the effect of OA was blocked by the inhibitor of chylomicron formation, Pluronic L-81. We also observed that intragastric triolein (TO) gavage was followed by increased plasma LPS, whereas gavage with tributyrin (TB), or TO plus Pluronic L-81, was not. Most intestinally absorbed LPS was present on chylomicron remnants (CM-R) in the blood. Chylomicron formation also promoted transport of LPS through mesenteric lymph nodes (MLN) and the production of TNFalpha mRNA in the MLN. Together, our data suggest that intestinal epithelial cells may release LPS on chylomicrons from cell-associated pools. Chylomicron-associated LPS may contribute to postprandial inflammatory responses or chronic diet-induced inflammation in chylomicron target tissues.

Corneal avascularity is due to soluble VEGF receptor-1

Corneal avascularity-the absence of blood vessels in the cornea-is required for optical clarity and optimal vision, and has led to the cornea being widely used for validating pro- and anti-angiogenic therapeutic strategies for many disorders. But the molecular underpinnings of the avascular phenotype have until now remained obscure and are all the more remarkable given the presence in the cornea of vascular endothelial growth factor (VEGF)-A, a potent stimulator of angiogenesis, and the proximity of the cornea to vascularized tissues. Here we show that the cornea expresses soluble VEGF receptor-1 (sVEGFR-1; also known as sflt-1) and that suppression of this endogenous VEGF-A trap by neutralizing antibodies, RNA interference or Cre-lox-mediated gene disruption abolishes corneal avascularity in mice. The spontaneously vascularized corneas of corn1 and Pax6+/- mice and Pax6+/- patients with aniridia are deficient in sflt-1, and recombinant sflt-1 administration restores corneal avascularity in corn1 and Pax6+/- mice. Manatees, the only known creatures uniformly to have vascularized corneas, do not express sflt-1, whereas the avascular corneas of dugongs, also members of the order Sirenia, elephants, the closest extant terrestrial phylogenetic relatives of manatees, and other marine mammals (dolphins and whales) contain sflt-1, indicating that it has a crucial, evolutionarily conserved role. The recognition that sflt-1 is essential for preserving the avascular ambit of the cornea can rationally guide its use as a platform for angiogenic modulators, supports its use in treating neovascular diseases, and might provide insight into the immunological privilege of the cornea.

Temporal gene expression profiles of target-ablated olfactory epithelium in mice with disrupted expression of scavenger receptor A: impact on macrophages

Target ablation [removal of the olfactory bulb (OBX)] induces apoptotic death of olfactory sensory neurons (OSNs) and an immune response in which activation and recruitment of macrophages (ms) into the olfactory epithelium (OE) occupy a central role. Ms phagocytose apoptotic neurons and secrete cytokines/growth factors that regulate subsequent progenitor cell proliferation and neurogenesis. Scavenger receptor A (SR-A) is a pattern recognition receptor that mediates binding of ms to apoptotic cells and other relevant immune response functions. The aim of this study was to determine the impact of the absence of SR-A on the immune response to OBX. The immune response to OBX was evaluated in mice in which functional expression of the m scavenger receptor (MSR) was eliminated by gene disruption (MSR-/-) and wild-type (wt) mice of the same genetic background. OBX induced significant apoptotic death of mature OSNs in the two strains. However, subsequent m infiltration and activation and progenitor cell proliferation were significantly reduced in MSR-/- vs. wt mice. Gene expression profiling at short intervals after OBX demonstrated significant differences in temporal patterns of expression of several gene categories, including immune response genes. Many immune response genes that showed different temporal patterns of expression are related to m function, including cytokine and chemokine secretion, phagocytosis, and m maturation and activation. These studies suggest that impairment of the immune response to OBX in the OE of MSR-/- mice most likely resulted from decreased m adhesion and subsequent reduced infiltration and activation, with a resultant decrease in neurogenesis.

Abnormal expression of the G-protein-activated inwardly rectifying potassium channel 2 (GIRK2) in hippocampus, frontal cortex, and substantia nigra of Ts65Dn mouse: a model of Down syndrome

Ts65Dn, a mouse model of Down syndrome (DS), demonstrates abnormal hippocampal synaptic plasticity and behavioral abnormalities related to spatial learning and memory. The molecular mechanisms leading to these impairments have not been identified. In this study, we focused on the G-protein-activated inwardly rectifying potassium channel 2 (GIRK2) gene that is highly expressed in the hippocampus region. We studied the expression pattern of GIRK subunits in Ts65Dn and found that GIRK2 was overexpressed in all analyzed Ts65Dn brain regions. Interestingly, elevated levels of GIRK2 protein in the Ts65Dn hippocampus and frontal cortex correlated with elevated levels of GIRK1 protein. This suggests that heteromeric GIRK1-GIRK2 channels are overexpressed in Ts65Dn hippocampus and frontal cortex, which could impair excitatory input and modulate spike frequency and synaptic kinetics in the affected regions. All GIRK2 splicing isoforms examined were expressed at higher levels in the Ts65Dn in comparison to the diploid hippocampus. The pattern of GIRK2 expression in the Ts65Dn mouse brain revealed by in situ hybridization and immunohistochemistry was similar to that previously reported in the rodent brain. However, in the Ts65Dn mouse a strong immunofluorescent staining of GIRK2 was detected in the lacunosum molecular layer of the CA3 area of the hippocampus. In addition, tyrosine hydroxylase containing dopaminergic neurons that coexpress GIRK2 were more numerous in the substantia nigra compacta and ventral tegmental area in the Ts65Dn compared to diploid controls. In summary, the regional localization and the increased brain levels coupled with known function of the GIRK channel may suggest an important contribution of GIRK2 containing channels to Ts65Dn and thus to DS neurophysiological phenotypes.

Loss of SPARC-mediated VEGFR-1 suppression after injury reveals a novel antiangiogenic activity of VEGF-A

VEGF-A promotes angiogenesis in many tissues. Here we report that choroidal neovascularization (CNV) incited by injury was increased by excess VEGF-A before injury but was suppressed by VEGF-A after injury. This unorthodox antiangiogenic effect was mediated via VEGFR-1 activation and VEGFR-2 deactivation, the latter via Src homology domain 2-containing (SH2-containing) tyrosine phosphatase-1 (SHP-1). The VEGFR-1-specific ligand placental growth factor-1 (PlGF-1), but not VEGF-E, which selectively binds VEGFR-2, mimicked these responses. Excess VEGF-A increased CNV before injury because VEGFR-1 activation was silenced by secreted protein, acidic and rich in cysteine (SPARC). The transient decline of SPARC after injury revealed a temporal window in which VEGF-A signaling was routed principally through VEGFR-1. These observations indicate that therapeutic design of VEGF-A inhibition should include consideration of the level and activity of SPARC.

Blockade of nociceptin/orphanin FQ transmission attenuates symptoms and neurodegeneration associated with Parkinson's disease

The opioid-like neuropeptide nociceptin/orphanin FQ (N/OFQ) and its receptor (NOP) are expressed in the substantia nigra (SN), a brain area containing dopamine neurons that degenerate in Parkinson's disease. Endogenous N/OFQ facilitates nigral glutamate release and inhibits nigrostriatal dopamine transmission and motor behavior. Here, we present evidence suggesting that endogenous N/OFQ may contribute to Parkinson's disease. Pharmacological blockade of the SN N/OFQ-NOP receptor system attenuated parkinsonian-like akinesia/hypokinesia in 6-hydroxydopamine hemilesioned or haloperidol-treated rats, whereas deletion of the NOP receptor gene conferred mice partial protection from haloperidol-induced motor depression. The antiparkinsonian action of NOP receptor antagonists was associated with reduction of glutamate release in the SN. In 6-hydroxydopamine hemilesioned rats, enhancement of N/OFQ expression and release was detected in the lesioned compared with the unlesioned SN, indicating that parkinsonism may be associated with overactivation of the N/OFQ-NOP receptor system in the SN. Finally, deletion of the N/OFQ gene conferred mice partial protection against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced loss of SN dopamine neurons. Based on these data, we propose that NOP receptor antagonists may represent a novel approach for combined (symptomatic and neuroprotective) therapy of Parkinson's disease.

Distribution of nociceptin/orphanin FQ in adult human brain

Nociceptin/orphanin FQ (N/OFQ), the endogenous agonist for the opioid receptor-like receptor 1 (ORL1), shows significant similarities to dynorphin A in structure and distribution in rat central nervous system. The distribution of N/OFQ in human brain has not been studied. We measured the concentrations of N/OFQ in 47 microdissected areas of the central nervous system of adult human brain using radioimmunoassay (RIA). Significant heterogeneity was found in the levels of N/OFQ concentration in the various analyzed regions. The highest concentrations were measured in the dorsal central gray matter (periaqueductal gray), the locus coeruleus, the ventromedial nucleus of hypothalamus, the septum and the dorsal horn of the spinal cord. High concentrations were also detected in other hypothamamic nuclei, the inferior colliculus, the ventral central gray matter, the pontine tegmentum, the amygdala, the reticular formation and the spinal trigeminal nucleus. Considerable similarity with the distribution of N/OFQ in rat CNS was observed. The widespread distribution in CNS predicts multifaceted functions for N/OFQ.

Dual oxidases represent novel hydrogen peroxide sources supporting mucosal surface host defense

Lactoperoxidase (LPO) is an enzyme with antimicrobial properties present in saliva, milk, tears, and airway secretions. Although the formation of microbicidal oxidants by LPO has been recognized for some time, the source of hydrogen peroxide (H2O2) for LPO-catalyzed reactions remains unknown. Reactive oxygen species produced by the phagocyte NADPH oxidase (phox) play a critical role in host defense against pathogens; however, analogous oxidant-generating systems in other tissues have not been associated with antimicrobial activity. Several homologues of gp91phox, the catalytic core of this enzyme, were described recently; dual oxidase (Duox)1/thyroid oxidase 1 and Duox2/thyroid oxidase 2 were identified in the thyroid gland and characterized as H2O2 donors for thyroxin biosynthesis. We examined Duox1 and Duox2 expression in secretory glands and on mucosal surfaces and give evidence for their presence and activity in salivary glands, rectum, trachea, and bronchium. Epithelial cells in salivary excretory ducts and rectal glands express Duox2, whereas tracheal and bronchial epithelial cells express Duox1. Furthermore, we detected Duox1-dependent H2O2 release by cultured human bronchial epithelial cells. Our observations suggest that Duox1 and Duox2 are novel H2O2 sources that can support LPO-mediated antimicrobial defense mechanisms on mucosal surfaces.

Traumatic brain injury induces nociceptin/orphanin FQ expression in neurons of the rat cerebral cortex

Nociceptin/orphanin FQ (N/OFQ) is a recently identified opioid-related neuropeptide. Earlier in vitro studies revealed regulation of N/OFQ expression by injury-induced factors, such as ciliary neurotrophic factor, inflammatory cytokines, and reactive oxygen species. We have extended our studies to in vivo experiments investigating the effect of traumatic brain injury on N/OFQ gene expression and peptide levels in the rat brain. Stab wound injury to the rat cerebral cortex led to a significant increase in N/OFQ mRNA levels in the vicinity of the injury, with the largest induction being seen at 24 h post-injury. Quantitative in situ hybridization revealed an almost twofold increase in the number of cells expressing N/OFQ, and the signal intensities within cells were also elevated. Stab wound injury leads to proliferation and hypertrophy of astrocytes, which respond to injury-related factors in vitro by up-regulating N/OFQ expression. However, in vivo N/OFQ co-localized exclusively with the neuronal marker, NeuN, following injury. N/OFQ expression was not detected in caspase-3-positive neurons undergoing apoptosis following injury, and increased N/OFQ expression was spatially more extended than the secondary injury-induced responses, such as astrogliosis and neuronal degeneration. Elevation of N/OFQ immunoreactivity closely followed the increase in N/OFQ gene expression as determined by immunohistochemistry. N/OFQ selectively activates the NOP receptor (ORL-1), but we did not detect parallel changes in levels of NOP receptor mRNA following injury, indicating regulation of the nociceptin system at the peptide and not the receptor level. In summary, a profound and prolonged up-regulation of N/OFQ expression in neurons surrounding a stab wound lesion to cerebral cortex was detected. The function of N/OFQ up-regulation in injury-induced responses in the brain is currently under investigation.

Proteins homologous to p47phox and p67phox support superoxide production by NAD(P)H oxidase 1 in colon epithelial cells

Superoxide production by phagocytes involves activation of a multi-component NADPH oxidase. Recently, several homologues of the catalytic component of the phagocyte oxidase, gp91phox, were identified in various tissues. Here we describe two proteins, p41 and p51, with significant homology to two cytosolic components of the phagocytic oxidase, p47phox and p67phox. Like p47phox, p41 contains an amino-terminal Phox homology domain, two SH3 domains, and a conserved carboxyl-terminal, proline-rich motif. Similarly, p51 is homologous to p67phox, containing four amino-terminal tetratrico-peptide repeats, a conserved "activation domain" motif, a PB1 domain, and a carboxyl-terminal SH3 domain. The highest levels of p41 transcript are detected in the colon and in other gastrointestinal tissues that express Nox1, the predominant gp91phox homologue in these tissues. In contrast, the p51 transcript showed a more widespread expression pattern, suggesting that it may support other tissue-specific oxidases. Mouse colon in situ hybridization detected both transcripts in the epithelial cells of colon crypts. Heterologous co-expression of p41 and p51 significantly enhances the superoxide-generating activity of Nox1-expressing cells; thus, p41 and p51 appear to be novel regulators of Nox1. These proteins also support the activity of gp91phox, albeit at much lower levels than the cytosolic phox counterparts. Our results suggest colon epithelial cells contain a multi-component NAD(P)H oxidase with a molecular architecture similar to the phagocytic oxidase.

Effect of parathyroid hormone levels on carotid intima-media thickness after renal transplantation

BACKGROUND

The present study aimed to investigate the intact parathyroid hormone (iPTH)-dependent evolution of common carotid intima-media thickness (CC IMT) in renal transplant recipients (RTR) within a 12-month follow-up, ie, before (E0) and 3 months (E3), 6 months (E6), and 12 months after renal transplantation (RTX).

METHODS

A total of 55 normotensive patients, aged 47 +/- 1.7 years, underwent a RTX. The graft function was stable (clearanceCockroft >60 mL/min and S-creatinine <2.5 mg/dL) in all patients throughout the follow-up.

RESULTS

In 67% of the RTR, the iPTH levels were classified as high at E0 (E6: 63%; E6: 49%; E12: 67%). The plasma iPTH levels decreased after RTX (P < .01). The arterial blood pressure remained stable. The CC IMT was positively and independently correlated with age (P < .01), gender (P < .01), and iPTH levels (P < .01).

CONCLUSIONS

Normalization of iPTH levels is associated with a significant intima-media thickness (IMT) reduction. The increased IMT in renal transplant recipients may contribute to the high cardiovascular morbidity and mortality in patients with end-stage renal failure.

Nigrostriatal innervation is preserved in Nurr1-null mice, although dopaminergic neuron precursors are arrested from terminal differentiation

Various factors, including the orphan nuclear receptor Nurr1, have been implicated in dopamine biosynthesis, but many of the specific events involved in this process have to be determined. Using genetic manipulations in mice, the obligatory role for Nurr1 in dopamine (DA) biosynthesis has been documented; however, the mechanism remains unclear. DA biosynthetic enzymes, transporters and receptors are absent in the substantia nigra (SN) and the ventral tegmental area (VTA) of Nurr1-null neonates. The current study establishes that the loss of Nurr1 function does not affect the normal ventralization of neuroepithelial cells to the ventral midbrain, their differentiation into neurons, and their topographical pattern in the SN and VTA. Futhermore, the absence of Nurr1 does not affect the survival of these DA precursor cells in the ventral midbrain, as determined by quantitative analysis of cells, expressing the general neuronal nuclear marker (NeuN) and the TUNEL assay for apoptosis. These neurons express cholecystokinin (CCK), a co-transmitter of dopaminergic neurons in this area. The untranslated exon 1-2 of the Nurr1 gene, which remains intact after homologous recombination, revealed the presence of dopaminergic precursors in the ventral midbrain of the Nurr1-null mice. In addition, these neurons establish their nigrostriatal projections, as shown by axonal transport of a fluorescent tracer, DiI. These results provide evidence that Nurr1 is essential for terminal differentiation of the dopaminergic neurons in the ventral midbrain but does not affect the early steps of their neurogenesis, migration, survival and striatal projections. Our findings suggest that activation of Nurr1 might be therapeutically useful in Parkinson's disease.

Effect of homocysteine on carotid intima-media thickness after renal transplantation

The common carotid intima-media thickness (CC IMT) is a strong predictor for cardiovascular disease in patients with end-stage renal failure. However, little is known about possible associations between potential cardiovascular risk factors such as serum total homocysteine concentrations (tHcy) and the CC IMT. Thus, we investigated (a) the course of tHcy levels after renal transplantation (RTX) and (b) the relationship between CC IMT and tHcy in 53 renal allograft recipients with chronic renal failure before transplantation and 3, 6, and 12 months after transplantation. Exclusion criteria were volume overload, symptomatic coronary artery disease, symptomatic cerebrovascular disease, peripheral artery disease, heart failure, valvular heart disease, diabetes mellitus, severe hypercholesterolemia, and blood pressure above 159/89 mmHg at the time of the investigation. In all renal allograft recipients, a carotid high-resolution B-mode ultrasound measurement of the CC IMT was performed. Eighteen patients had normal ( < 20 micromol/L) pre-transplant (U0) tHcy, 25 had moderately elevated (20-40 micromol/L) pre-transplant (U0) tHcy, and 10 had severely elevated (> 40 micromol/L) pre-transplant (U0) tHcy. After 12 months of follow-up time (U12), no statistically significant differences concerning the tHcy levels could be detected between the groups (average serum tHcy 16.4 micromol/L +/- 1.1 micromol/L). The CC IMT did not differ significantly between the three tHcy groups at any time within the present follow-up. This was also true for the 'wall-to-lumen ratio'. A multiple forward stepwise regression analysis showed that the reduction of the CC IMT was positively correlated with gender (p < 0.01), glucose levels at U12 (p < 0.05; r2 = 0.96), systolic arterial blood pressure at U12 (p < 0.05; r2 = 0.97), and with the intact parathyroid hormone levels at U0 (p < 0.01; r2 = 0.98). In conclusion, (a) tHcy decreases significantly after RTX, but (b) does not influence the CC IMT thickness independently.

Vessel wall alterations in patients with renal failure

Cardiovascular complications are a major cause of morbidity and mortality in patients with renal failure. Death due to myocardial infarction and to stroke is more frequent in hemodialysis patients than in the total population. These cardiovascular diseases are mainly the consequence of atherosclerosis and cause decreased life expectancy in patients with renal failure. Ultrasound techniques now make it possible to measure atherosclerotic lesions in big and medium-sized arteries. Thickening of the intima-media-complex is an early sign of atherosclerosis in these vessels. It reduces the distensibility of the arteries during systole. The distensibility of big and medium-sized arteries can be determined using ultrasound-doppler-techniques. In our studies, the intima-media-thickness of the carotid artery was significantly (p< 0.01) increased in patients with chronic renal failure (1.32+/-0.49 mm, n=28) as compared with aged-matched healthy control subjects (0.75 +/- 0.20, n= 29). The distensibility coefficient was higher (p< 0.05) in healthy controls (26 +/- 1.8 10(-3)/kPa, n= 12) than in patients with renal insufficiency (19 +/- 1.7 10(-3)/kPa, n = 12). This demonstrates increased stiffness of the vessel wall resulting in loss of Windkessel function and increased work load of the heart.

Studies on structural changes of the carotid arteries and the heart in asymptomatic renal transplant recipients

BACKGROUND

The present study was designed to characterize early structural changes of large arteries in renal transplant recipients with no clinical evidence of cardiovascular disease and normal blood pressure values, and to analyse the relationship between arterial alterations and those of the heart.

METHODS

Intima media thickness and atherosclerotic plaques of the carotid arteries as well as left ventricular geometry and function were examined in 35 asymtomatic renal transplant recipients and 29 age- and sex-matched healthy controls by high resolution B-mode ultrasound and by echocardiography.

RESULTS

Intima-media thickness of the carotid arteries was significantly higher in renal transplant recipients (1.21+/-0.08 mm) than in healthy controls (0.74+/-0.04 mm) (P<0.001). Atherosclerotic plaques were found in the majority of renal transplant recipients (71% vs 14% in healthy controls, P<0.001). Left ventricular mass index was significantly increased in the group of renal transplant recipients (264+/-13 g, 146+/-7 g/m2) when compared with healthy controls (155+/-8 g, 83+/-4 g/m2) (P<0.001). Multiple regression analysis in renal transplant recipients showed that intima media thickness of the carotid arteries was significantly related to left ventricular mass index (P<0.02), but not to age, blood pressure, body mass index, serum creatinine, cholesterol and lipoprotein (a) levels. In the group of healthy controls, intima-media thickness of the carotid artery was related to age (P<0.002), but not to left ventricular mass index or the other independent variables.

CONCLUSIONS

The present study documents pronounced intima-media thickening in asymptomatic renal transplant recipients. Atherosclerotic lesions are present in most renal transplant recipients with no clinical evidence of cardiovascular disease. We observed a parallelism between arterial wall thickening and left ventricular hypertrophy, although blood pressure levels were normal during haemodialysis therapy and after renal transplantation.

Dopamine biosynthesis is selectively abolished in substantia nigra/ventral tegmental area but not in hypothalamic neurons in mice with targeted disruption of the Nurr1 gene

To ascertain the function of an orphan nuclear receptor Nurr1, a transcription factor belonging to a large gene family that includes receptors for steroids, retinoids, and thyroid hormone, we generated Nurr1-null mice by homologous recombination. Mice, heterozygous for a single mutated Nurr1 allele, appear normal, whereas mice homozygous for the null allele die within 24 h after birth. Dopamine (DA) was absent in the substantia nigra (SN) and ventral tegmental area (VTA) of Nurr1-null mice, consistent with absent tyrosine hydroxylase (TH), L-aromatic amino acid decarboxylase, and other DA neuron markers. TH immunoreactivity and mRNA expression in hypothalamic, olfactory, and lower brain stem regions were unaffected. L-Dihydroxyphenylalanine treatments, whether given to the pregnant dams or to the newborns, failed to rescue the Nurr1-null mice. We were unable to discern differences between null and wild-type mice in the cellularity, presence of neurons, or axonal projections to the SN and VTA. These findings provide evidence for a new mechanism of DA depletion in vivo and suggest a unique role for Nurr1 in fetal development and/or postnatal survival.

Elemental mercurial poisoning

A 39-year-old man injected 40 mL of elemental mercury in an attempted suicide 3 years before coming to our facility. No specific treatment regimen had been done since then. Chest x-ray films showed mercury deposits in the lungs, as well as around the injection site. The mercury concentration in his blood was at 96.3 micrograms (0.480 nmol/L), thus significantly elevated (given a reference range of up to 2 micrograms Hg/L), as was the renal mercury elimination. Despite mercurial deposits within the pulmonary circulation, the pulmonary function showed normal values, with no reduction of the diffusion capacity. There were signs of polyneuropathy. The patient was given sodium dimercaptopropanesulfate (Dimaval) for mercury complexation. This case report outlines the diagnosis and therapy for mercurial poisoning through metallic mercury.

Reduced distensibility of the common carotid artery in patients treated with ergotamine

To investigate the effect of vascular smooth muscle contraction on mechanical vessel wall properties of proximal "elastic" arteries, we investigated the effect of the vasoconstrictor ergotamine on the distensibility of the common carotid artery in 10 migraine patients with ergotamine intake, in 10 control patients with migraine headache but no prior ergotamine intake, and in 10 healthy control subjects. The patients and control subjects were matched for age, blood pressure, and sex. In the ergotamine group, 2.2 +/- 1.4 mg ergotamine tartrate (0.25 to 6 mg) was taken within 12 hours before investigation. Differences in mean 24-hour blood pressure between the study groups were excluded by 24-hour blood pressure recording and differences in arterial wall thickness by high-resolution and differences in arterial wall thickness by high-resolution B-mode ultrasound. A multigate Doppler system was used for measurement of vessel wall movements by M-mode Doppler analysis. Blood pressure was determined by sphygmomanometry. The end-diastolic diameter of the common carotid artery was insignificantly reduced in the ergotamine group compared with the healthy control subjects and control patients (healthy control subjects, 6.6 +/- 0.4 mm; control patients, 6.7 +/- 0.5 mm; patients with ergotamine intake, 6.3 +/- 0.4 mm; P = NS). Arterial distensibility was significantly lower in the patients with ergotamine intake (17.4 +/- 4.0 10(-3)/kPa) than in the healthy control subjects (22.3 +/- 5.1 10(-3)/kPa) and control patients (22.8 +/- 3.6 10(-3)/kPa) (one-way ANOVA, P = .014). The results show that ergotamine reduces the distensibility of the common carotid artery. The data suggest that vascular smooth muscle contraction can modulate the buffering function of the arterial system independently of blood pressure changes.