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Junction Function (junction + function)

Distribution by Scientific Domains

Medical Sciences	80%

Selected Abstracts

Criteria for Pacemaker Explant in Patients Without a Precise Indication for Pacemaker Implantation

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 3 2002
MARTINO MARTINELLI
MARTINELLI, M., et al.: Criteria for Pacemaker Explant in Patients Without a Precise Indication for Pacemaker Implantation. Unnecessary pacemaker implantation may cause significant social and psychological consequences, the inconvenience of periodic office visits, and the expense of pulse generator replacement. Establishing adequate criteria for explanting pacemakers is crucial and has not yet been described. This study presents the results of a study protocol for explanting the pacemaker in patients without a clear indication for pacemaker implantation. Seventy pacemaker users without a clear reason for the implantation were included in the study conducted from August 1986 to November 1998 and were prospectively followed. The investigation consisted of clinical and neurological evaluations, echocardiogram, exercise testing, and tilt table testing. When these tests were negative, the pulse generator energy and stimulation rates were reprogrammed to the lowest values. Periodic Holter monitoring was conducted during follow-up. When asymptomatic for 1 year, patients underwent an electrophysiological evaluation of sinus and atrioventricular junction function and ventricular vulnerability. When the electrophysiological study was negative, pacemaker explantation was performed. Of the 70 patients, 35 had their pacemaker explanted; 3 were excluded due to a positive tilt table test and electrophysiological study, and 3 are waiting for pacemaker explantation. Mean follow-up after pacemaker explantation was 30.3 months, and all patients remained asymptomatic, except for one patient who died of a noncardiac cause. Critical analysis of pacemaker users without a well-established indication is justified because it may allow pacemaker explant in a significant proportion of these patients, and it may bring considerable social, economic, and psychological benefits. [source]

GJB2 Mutations in Mongolia: Complex Alleles, Low Frequency, and Reduced Fitness of the Deaf

ANNALS OF HUMAN GENETICS, Issue 2 2010
Mustafa Tekin
SUMMARY We screened the GJB2 gene for mutations in 534 (108 multiplex and 426 simplex) probands with non-syndromic sensorineural deafness, who were ascertained through the only residential school for the deaf in Mongolia, and in 217 hearing controls. Twenty different alleles, including four novel changes, were identified. Biallelic GJB2 mutations were found in 4.5% of the deaf probands (8.3% in multiplex, 3.5% in simplex). The most common mutations were c.IVS1 + 1G > A (c.-3201G > A) and c.235delC with allele frequencies of 3.5% and 1.5%, respectively. The c.IVS1 + 1G > A mutation appears to have diverse origins based on associated multiple haplotypes. The p.V27I and p.E114G variants were frequently detected in both deaf probands and hearing controls. The p.E114G variant was always in cis with the p.V27I variant. Although in vitro experiments using Xenopus oocytes have suggested that p.[V27I;E114G] disturbs the gap junction function of Cx26, the equal distribution of this complex allele in both deaf probands and hearing controls makes it a less likely cause of profound congenital deafness. We found a lower frequency of assortative mating (37.5%) and decreased genetic fitness (62%) of the deaf in Mongolia as compared to the western populations, which provides an explanation for lower frequency of GJB2 deafness in Mongolia. [source]

Vascular and Biology 05

BRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue S1 2002
L. Yea
Background: Tight junctions govern the permeability of endothelial and epithelial cells. Changes in tight junction function are thus an early and key event in cancer metastasis and tissue permeability. This study sought to determine the role of oestrogen in the regulation of tight junctions and expression of occludin in endothelial cells. Methods: Human vascular endothelial cell line was incubated with 17-,-oestradiol at different concentrations (from 10,11m to 10,7m) over 1,24 h. Expression of occludin mRNA was determined using RT-PCR, and change of occludin protein using Western blotting. Transendothelial resistance (TER) was measured with an EVOM, and transendothelial cell permeability was determined using fluorescence labelled dextran (FITC-dextran 10) with a multichannel fluorescence reader. Results: 17-,-oestradiol reduced the expression of occludin mRNA in a time and concentration dependent manner with an obvious effect starting from 4 h. Reduced level of occludin protein was similarly seen after treatment with 17-,-oestradiol. Incubation of HECV with 17-,-oestradiol resulted in an increase in paracellular permeability by 9.9 ± 8.9 per cent at 10,10m (P > 0.05 versus control), 42.1 ± 15.2 per cent at 10,9m (P < 0.05 versus control), and 40.1 ± 22.4 per cent at 10,8m (P < 0.05, versus control). A decrease in the transendothelial cell resistance (TER) was seen with oestradiol (a reduction by 18.6 ± 16.6 per cent (P > 0.05 versus control), 31.5 ± 10.6 per cent (P < 0.01), or 44.4 ± 18.4 per cent (P < 0.01), at concentration 10,10, 10,9, 10,8m, respectively. Conclusions: This study shows a perturbation of tight junction functions in endothelial cells by oestrogen, which may have implications in the aetiology of mastalgia and vascular spread of breast cancer. [source]

c-Kit+ Bone Marrow Stem Cells Differentiate into Functional Cardiac Myocytes

CLINICAL AND TRANSLATIONAL SCIENCE, Issue 1 2009
Hajime Kubo Ph.D.
Abstract The utility of bone marrow cells (BMCs) to regenerate cardiac myocytes is controversial. The present study examined the capacity of different types of BMCs to generate functional cardiac myocytes. Isolated c-kit+ BMCs (BMSCs), c-kit+ and crude BMCs from the adult feline femur were membrane stained with PKH26 dye or infected with a control enhanced green fluorescence protein transcript (EGFP)-adenovirus prior to co-culture upon neonatal rat ventricular myocytes (NRVM). Co-cultured cells were immuno-stained for c-kit, ,-tropomyosin, ,-actinin, connexin 43 (C×43) and Ki67 and analyzed with confocal microscopy. Electrophysiology of BMSC derived myocytes were compared to NRVMs within the same culture dish. Gap junction function was analyzed by fluorescence recovery after photo-bleaching (FRAP). BMCs proliferated and differentiated into cardiac myocytes during the first 48 hours of co-culturing. These newly formed cardiac myocytes were able to contract spontaneously or synchronously with neighboring NRVMs. The myogenic rate of c-kit+ BMSCs was significantly greater than c-kit+ and crude BMCs (41.2 ± 2.1, 6.1 ± 1.2, and 17.1 ± 1.5%, respectively). The newly formed cardiac myocytes exhibited an immature electrophysiological phenotype until they became electrically coupled to NRVMs through functional gap junctions. BMSCs did not become functional myocytes in the absence of NRVMs. In conclusion, c-kit+ BMSCs have the ability to transdifferentiate into functional cardiac myocytes. [source]