Transauricular embolization of the rabbit coronary artery for experimental myocardial infarction: comparison of a minimally invasive closed-chest model with open-chest surgery

<p>Abstract</p> <p>Introduction</p> <p>To date, most animal studies of myocardial ischemia have used open-chest models with direct surgical coronary artery ligation. We aimed to develop a novel, percutaneous, minimally-invasive, closed-chest model of experimental myocardial infarction (EMI) in the New Zealand White rabbit and compare it with the standard open-chest surgical model in order to minimize local and systemic side-effects of major surgery.</p> <p>Methods</p> <p>New Zealand White rabbits were handled in conformity with the "Guide for the Care and Use of Laboratory Animals" and underwent EMI under intravenous anesthesia. Group A underwent EMI with an open-chest method involving surgical tracheostomy, a mini median sternotomy incision and left anterior descending (LAD) coronary artery ligation with a plain suture, whereas Group B underwent EMI with a closed-chest method involving fluoroscopy-guided percutaneous transauricular intra-arterial access, superselective LAD catheterization and distal coronary embolization with a micro-coil. Electrocardiography (ECG), cardiac enzymes and transcatheter left ventricular end-diastolic pressure (LVEDP) measurements were recorded. Surviving animals were euthanized after 4 weeks and the hearts were harvested for Hematoxylin-eosin and Masson-trichrome staining.</p> <p>Results</p> <p>In total, 38 subjects underwent EMI with a surgical (n = 17) or endovascular (n = 21) approach. ST-segment elevation (1.90 ± 0.71 mm) occurred sharply after surgical LAD ligation compared to progressive ST elevation (2.01 ± 0.84 mm;p = 0.68) within 15-20 min after LAD micro-coil embolization. Increase of troponin and other cardiac enzymes, abnormal ischemic Q waves and LVEDP changes were recorded in both groups without any significant differences (p > 0.05). Infarct area was similar in both models (0.86 ± 0.35 cm in the surgical group vs. 0.92 ± 0.54 cm in the percutaneous group;p = 0.68).</p> <p>Conclusion</p> <p>The proposed model of transauricular coronary coil embolization avoids thoracotomy and major surgery and may be an equally reliable and reproducible platform for the experimental study of myocardial ischemia.</p

Spectrum of Genetic Changes in Patients with Non-Syndromic Hearing Impairment and Extremely High Carrier Frequency of 35delG GJB2 Mutation in Belarus

The genetic nature of sensorineural hearing loss (SNHL) has so far been studied for many ethnic groups in various parts of the world. The single-nucleotide guanine deletion (35delG) of the GJB2 gene coding for connexin 26 was shown to be the main genetic cause of autosomal recessive deafness among Europeans. Here we present the results of the first study of GJB2 and three mitochondrial mutations among two groups of Belarusian inhabitants: native people with normal hearing (757 persons) and 391 young patients with non-syndromic SNHL. We have found an extremely high carrier frequency of 35delG GJB2 mutation in Belarus −5.7%. This point deletion has also been detected in 53% of the patients with SNHL. The 312del14 GJB2 was the second most common mutation in the Belarus patient cohort. Mitochondrial A1555G mt-RNR1 substitution was found in two SNHL patients (0.55%) but none were found in the population cohort. No individuals carried the A7445G mutation of mitochondrial mt-TS1. G7444A as well as T961G substitutions were detected in mitochondrial mt-RNR1 at a rate of about 1% both in the patient and population cohorts. A possible reason for Belarusians having the highest mutation carrier frequency in Europe 35delG is discussed

Possible involvement of caveolin in attenuation of cardioprotective effect of ischemic preconditioning in diabetic rat heart

<p>Abstract</p> <p>Background</p> <p>Nitric oxide (NO) has been noted to produce ischemic preconditioning (IPC)-mediated cardioprotection. Caveolin is a negative regulator of NO, which inhibits endothelial nitric oxide synthase (eNOS) by making caveolin-eNOS complex. The expression of caveolin is increased during diabetes mellitus (DM). The present study was designed to investigate the involvement of caveolin in attenuation of the cardioprotective effect of IPC during DM in rat.</p> <p>Methods</p> <p>Experimental DM was induced by single dose of streptozotocin (50 mg/Kg, <it>i.p</it>,) and animals were used for experiments four weeks later. Isolated heart was mounted on Langendorff's apparatus, and was subjected to 30 min of global ischemia and 120 min of reperfusion. IPC was given by four cycles of 5 min of ischemia and 5 min of reperfusion with Kreb's-Henseleit solution (K-H). Extent of injury was measured in terms of infarct size by triphenyltetrazolium chloride (TTC) staining, and release of lactate dehydrogenase (LDH) and creatin kinase-MB (CK-MB) in coronary effluent. The cardiac release of NO was noted by measuring the level of nitrite in coronary effluent.</p> <p>Results</p> <p>IPC- induced cardioprotection and release of NO was significantly decreased in diabetic rat heart. Pre-treatment of diabetic rat with daidzein (DDZ) a caveolin inhibitor (0.2 mg/Kg/s.c), for one week, significantly increased the release of NO and restored the attenuated cardioprotective effect of IPC. Also perfusion of sodium nitrite (10 μM/L), a precursor of NO, significantly restored the lost effect of IPC, similar to daidzein in diabetic rat. Administration of 5-hydroxy deaconate (5-HD), a mito K_ATPchannel blocker, significantly abolished the observed IPC-induced cardioprotection in normal rat or daidzein and sodium nitrite perfused diabetic rat heart alone or in combination.</p> <p>Conclusions</p> <p>Thus, it is suggested that attenuation of the cardioprotection in diabetic heart may be due to decrease the IPC mediated release of NO in the diabetic myocardium, which may be due to up -regulation of caveolin and subsequently decreased activity of eNOS.</p

The soluble guanylate cyclase activator cinaciguat prevents cardiac dysfunction in a rat model of type-1 diabetes mellitus

BACKGROUND: Diabetes mellitus (DM) leads to the development of diabetic cardiomyopathy, which is associated with altered nitric oxide (NO)-soluble guanylate cyclase (sGC)-cyclic guanosine monophosphate (cGMP) signalling. Cardioprotective effects of elevated intracellular cGMP-levels have been described in different heart diseases. In the current study we aimed at investigating the effects of pharmacological activation of sGC in diabetic cardiomyopathy. METHODS: Type-1 DM was induced in rats by streptozotocin. Animals were treated either with the sGC activator cinaciguat (10 mg/kg/day) or with placebo orally for 8 weeks. Left ventricular (LV) pressure-volume (P-V) analysis was used to assess cardiac performance. Additionally, gene expression (qRT-PCR) and protein expression analysis (western blot) were performed. Cardiac structure, markers of fibrotic remodelling and DNA damage were examined by histology, immunohistochemistry and TUNEL assay, respectively. RESULTS: DM was associated with deteriorated cGMP signalling in the myocardium (elevated phosphodiesterase-5 expression, lower cGMP-level and impaired PKG activity). Cardiomyocyte hypertrophy, fibrotic remodelling and DNA fragmentation were present in DM that was associated with impaired LV contractility (preload recruitable stroke work (PRSW): 49.5 +/- 3.3 vs. 83.0 +/- 5.5 mmHg, P < 0.05) and diastolic function (time constant of LV pressure decay (Tau): 17.3 +/- 0.8 vs. 10.3 +/- 0.3 ms, P < 0.05). Cinaciguat treatment effectively prevented DM related molecular, histological alterations and significantly improved systolic (PRSW: 66.8 +/- 3.6 mmHg) and diastolic (Tau: 14.9 +/- 0.6 ms) function. CONCLUSIONS: Cinaciguat prevented structural, molecular alterations and improved cardiac performance of the diabetic heart. Pharmacological activation of sGC might represent a new therapy approach for diabetic cardiomyopathy

Common Molecular Etiologies Are Rare in Nonsyndromic Tibetan Chinese Patients with Hearing Impairment

Background: Thirty thousand infants are born every year with congenital hearing impairment in mainland China. Racial and regional factors are important in clinical diagnosis of genetic deafness. However, molecular etiology of hearing impairment in the Tibetan Chinese population living in the Tibetan Plateau has not been investigated. To provide appropriate genetic testing and counseling to Tibetan families, we investigated molecular etiology of nonsyndromic deafness in this population. Methods: A total of 114 unrelated deaf Tibetan children from the Tibet Autonomous Region were enrolled. Five prominent deafness-related genes, GJB2, SLC26A4, GJB6, POU3F4, and mtDNA 12S rRNA, were analyzed. Inner ear development was evaluated by temporal CT. A total of 106 Tibetan hearing normal individuals were included as genetic controls. For radiological comparison, 120 patients, mainly of Han ethnicity, with sensorineural hearing loss were analyzed by temporal CT. Results: None of the Tibetan patients carried diallelic GJB2 or SLC26A4 mutations. Two patients with a history of aminoglycoside usage carried homogeneous mtDNA 12S rRNA A1555G mutation. Two controls were homozygous for 12S rRNA A1555G. There were no mutations in GJB6 or POU3F4. A diagnosis of inner ear malformation was made in 20.18 % of the Tibetan patients and 21.67 % of the Han deaf group. Enlarged vestibular aqueduct, the most common inner ear deformity, was not found in theTibetan patients, but was seen in 18.33 % of the Han patients. Common molecular etiologies

GJB2 mutation spectrum in 2063 Chinese patients with nonsyndromic hearing impairment

Background: Mutations in GJB2 are the most common molecular defects responsible for autosomal recessive nonsyndromic hearing impairment (NSHI). The mutation spectra of this gene vary among different ethnic groups. Methods: In order to understand the spectrum and frequency of GJB2 mutations in the Chinese population, the coding region of the GJB2 gene from 2063 unrelated patients with NSHI was PCR amplified and sequenced. Results: A total of 23 pathogenic mutations were identified. Among them, five (p.W3X, c.99delT, c.155_c.158delTCTG, c.512_c.513insAACG, and p.Y152X) are novel. Three hundred and seven patients carry two confirmed pathogenic mutations, including 178 homozygotes and 129 compound heterozygotes. One hundred twenty five patients carry only one mutant allele. Thus, GJB2 mutations account for 17.9% of the mutant alleles in 2063 NSHI patients. Overall, 92.6% (684/739) of the pathogenic mutations are frame-shift truncation or nonsense mutations. The four prevalent mutations; c.235delC, c.299_c.300delAT, c.176_c.191del16, and c.35delG, account for 88.0% of all mutantalleles identified. The frequency of GJB2 mutations (alleles) varies from 4% to 30.4% among different regions of China. It also varies among different sub-ethnic groups. Conclusion: In some regions of China, testing of the three most common mutations can identify at least one GJB2 mutant allele in all patients. In other regions such as Tibet, the three most common mutations account for only 16% the GJB2 mutant alleles. Thus, in this region, sequencing of GJB2 would be recommended. In addition, the etiology of more than 80% of the mutant alleles for NSHI in China remains to be identified. Analysis of other NSHI related genes will be necessary

Geochemical response of the mid-depth Northeast Atlantic Ocean to freshwater input during Heinrich events 1 to 4

PublishedArticleHeinrich events are intervals of rapid iceberg-sourced freshwater release to the high latitude North Atlantic Ocean that punctuate late Pleistocene glacials. Delivery of fresh water to the main North Atlantic sites of deep water formation during Heinrich events may result in major disruption to the Atlantic Meridional Overturning Circulation (AMOC), however, the simple concept of an AMOC shutdown in response to each freshwater input has recently been shown to be overly simplistic. Here we present a new multi-proxy dataset spanning the last 41,000 years that resolves four Heinrich events at a classic mid-depth North Atlantic drill site, employing four independent geochemical tracers of water mass properties: boron/calcium, carbon and oxygen isotopes in foraminiferal calcite and neodymium isotopes in multiple substrates. We also report rare earth element distributions to investigate the fidelity by which neodymium isotopes record changes in water mass distribution in the northeast North Atlantic. Our data reveal distinct geochemical signatures for each Heinrich event, suggesting that the sites of fresh water delivery and/or rates of input played at least as important a role as the stage of the glacial cycle in which the fresh water was released. At no time during the last 41 kyr was the mid-depth northeast North Atlantic dominantly ventilated by southern-sourced water. Instead, we document persistent ventilation by Glacial North Atlantic Intermediate Water (GNAIW), albeit with variable properties signifying changes in supply from multiple contributing northern sources.This research used samples provided by the Integrated Ocean Drilling (Discovery) Program IODP, which is sponsored by the US National Science Foundation and participating countries under management of Joint Oceanographic Institutions, Inc. We thank Walter Hale and Alex Wülbers for help with sampling, Kirsty Crocket for providing additional samples and Matt Cooper, Andy Milton, Mike Bolshaw and Dave Spanner for analytical support. Heiko Pälike, David Thornalley and Rachel Mills are thanked for productive discussions and comments on earlier versions of this work. We also thank three anonymous reviewers for their constructive feedback, which greatly improved the manuscript. Funding for this project was provided by NERC studentships to A.J.C. (grant NE/D005728/2) and T.B.C. (NE/I528626/1), with additional funding support from a Royal Society Wolfson Research Merit Award and NERC grants NE/F00141X/1 and NE/I006168/1 to P.A.W. and NE/D00876X/2 to G.L.F