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11.
F. C. Howarth Allan J. Levi Jules C. Hancox 《Pflügers Archiv : European journal of physiology》1996,431(5):713-722
The delayed rectifier potassium current (I
K) is known to be important in action potential repolarisation and may contribute to the diastolic pacemaker depolarisation
in pacemaker cells from the heart. In this study, using whole-cell patch clamp, we investigated the characteristics of I
K in morphologically normal cells from the atrioventricular node (AVN) and ventricle of the rabbit heart. Cells were held at
−40 mV and 5 μM external nifedipine was used to block L-type calcium current (I
Ca,L). Significant I
K was observed with pulses to potentials more positive than −30 mV. The steady-state activation curve in both cell types showed
maximal activation at between + 10 and + 20 mV. Half-maximal activation of I
K occurred at −4.9 and −4.1 mV with slope factors of 8.3 and 12.4 mV in ventricular and AVN cells, respectively. Using pulses
of increasing duration, significant I
K tails after repolarisation from + 40 mV were observed with pulses of 20 ms and increased with pulses up to 100–120 ms in
both cell types. Pulses of longer duration did not activate further I
K and this suggested that only the rapid component of I
K, called I
Kr, was present in either cell type. Moreover, I
K tails after pulses to all potentials were blocked completely by E-4031, a selective blocker of I
Kr. The reversal potential of I
K varied with the concentration of external K. Superfusion of AVN cells with medium containing 4, 15 and 40 mM [K+]o resulted in reversal potentials of −81, −56 and −32 mV, respectively, which are close to values predicted if the I
K channel were highly selective for K. The time constants for deactivation of I
K in ventricle and AVN on return to −40 mV after a 500-ms activating pulse to + 60 mV were 480 ms and 230 ms, respectively.
The faster deactivation of I
K in AVN cells was a distinguishing feature and suggests that there may be differences in the I
Kr channel protein between ventricular and AVN cells.
Received: 24 July 1995 /Received after revision: 20 October 1995 /Accepted: 23 October 1995 相似文献
12.
Using electrophysiological and radiotracer studies in parallel, we have investigated the characteristics of the endogenous Na+-dependent amino acid transporter (system B0,+) in Xenopus oocytes with regard to ion dependence, voltage dependence and transport stoichiometry. In voltage-clamped oocytes (–60 mV) superfusion with saturating concentrations of amino acids (1 mM) in 100 mM NaCl resulted in reversible, inward currents (mean±SEM): alanine, 1.83±0.09 nA (n=21); arginine, 2.54±0.18 nA (n=17); glutamine, 1.73±0.10 nA (n=19). Only arginine evoked a current in choline medium (0.50±0.13 nA, n=10), whereas Cl– replacement had no effect on evoked currents. The glutamine-evoked current was saturable (I
max=1.73 nA, glutamine K
m=0.12 mM) and linearly dependent upon voltage between –90 and –30 mV. Using direct and indirect (activation) methods, we found that transport can proceed with Na+/amino acid coupling stoichiometry of either 11 or 21, but coupling was the same for each amino acid tested (alanine, arginine and glutamine) within a batch of oocytes (i.e. from a single toad). Despite the net single positive charge on arginine, the magnitude of the net transmembrane charge movement during Na+-coupled arginine transport was identical to that for the zwitterionic neutral amino acids glutamine and alanine; this may be explained by a concomitant stimulation of K+ efflux during arginine transport with a putative coupling of 1 K+1 arginine. 相似文献
13.
Jules?J?BermanEmail author Mary?E?Edgerton Bruce?A?Friedman 《BMC medical informatics and decision making》2003,3(1):5
Background
Tissue Microarrays (TMAs) allow researchers to examine hundreds of small tissue samples on a single glass slide. The information held in a single TMA slide may easily involve Gigabytes of data. To benefit from TMA technology, the scientific community needs an open source TMA data exchange specification that will convey all of the data in a TMA experiment in a format that is understandable to both humans and computers. A data exchange specification for TMAs allows researchers to submit their data to journals and to public data repositories and to share or merge data from different laboratories. In May 2001, the Association of Pathology Informatics (API) hosted the first in a series of four workshops, co-sponsored by the National Cancer Institute, to develop an open, community-supported TMA data exchange specification. 相似文献14.
15.
Emma Bell Grant Townsend David Wilson Jules Kieser Toby Hughes 《American journal of human biology》2001,13(5):690-698
Abnormal growth in Down syndrome (DS) is reflected by variable reduction in size and simplification in form of many physical traits. This study aimed to compare the thickness of enamel and dentine in deciduous and permanent mandibular incisor teeth between DS and non‐DS individuals and to clarify how these tissues contribute to altered tooth size in DS. Sample groups comprised 61 mandibular incisors (29 permanent and 32 deciduous) from DS individuals and 55 mandibular incisors (29 permanent and 26 deciduous) from non‐DS individuals. Maximum mesiodistal and labiolingual crown dimensions were measured initially, then the crowns were sectioned midsagittally and photographed using a stereomicroscope. Linear measurements of enamel and dentine thickness were obtained on the labial and lingual surfaces of the crowns, together with enamel and dentine–pulp areas and lengths of the dentino‐enamel junction. Reduced permanent crown size in DS was associated with a reduction in both enamel and dentine thickness. After adjustments were made for tooth size, DS permanent incisors had significantly thinner enamel than non‐DS permanent teeth. The DS permanent teeth also exhibited significant differences in shape and greater variability in dimensions than the non‐DS permanent teeth. Crown dimensions of deciduous incisors were similar in size or larger in DS compared with non‐DS deciduous teeth. Enamel and dentine thicknesses of the deciduous teeth were similar in DS and non‐DS individuals. The findings indicate that growth retardation in DS reduces both enamel and dentine deposition in the permanent incisors but not in the earlier‐forming deciduous predecessors. The results are also consistent with the concept of amplified developmental instability for dental traits in DS. Am. J. Hum. Biol. 13:690–698, 2001. © 2001 Wiley‐Liss, Inc. 相似文献
16.
Stefano Pini Valéria de Queiroz Daniel Pagnin Lukas Pezawas Jules Angst Giovanni B Cassano Hans-Ulrich Wittchen 《European neuropsychopharmacology》2005,15(4):425-434
A literature search, supplemented by an expert survey and selected reanalyses of existing data from epidemiological studies was performed to determine the prevalence and associated burden of bipolar I and II disorder in EU countries. Only studies using established diagnostic instruments based on DSM-III-R or DSM-IV, or ICD-10 criteria were considered. Fourteen studies from a total of 10 countries were identified. The majority of studies reported 12-month estimates of approximately 1% (range 0.5-1.1%), with little evidence of a gender difference. The cumulative lifetime incidence (two prospective-longitudinal studies) is slightly higher (1.5-2%); and when the wider range of bipolar spectrum disorders is considered estimates increased to approximately 6%. Few studies have reported separate estimates for bipolar I and II disorders. Age of first onset of bipolar disorder is most frequently reported in late adolescence and early adulthood. A high degree of concurrent and sequential comorbidity with other mental disorders and physical illnesses is common. Most studies suggest equally high or even higher levels of impairments and disabilities of bipolar disorders as compared to major depression and schizophrenia. Few data are available on treatment and health care utilization. 相似文献
17.
Wendy A G Stams Monique L den Boer H Berna Beverloo Jules P P Meijerink Elisabeth R van Wering Gritta E Janka-Schaub Rob Pieters 《Clinical cancer research》2005,11(8):2974-2980
PURPOSE: t(12;21)(p13; q22), present in approximately 25% of pediatric precursor B-ALL, is highly sensitivity to L-asparaginase and the prognosis depends on the intensity of the treatment protocol. This study analyzes the relationship between the mRNA expression of the genes and fusion products involved in t(12;21), in vitro sensitivity to prednisolone, vincristine, and L-asparaginase, and long-term clinical outcome in t(12;21)+ acute lymphoblastic leukemia (ALL) patients. EXPERIMENTAL DESIGN: Long-term clinical outcome in 45 t(12;21)+ ALL patients was related to mRNA expression of TEL, AML1, TEL-AML1, and AML1-TEL, determined by real-time quantitative PCR, and the in vitro sensitivity to prednisolone, vincristine, and L-asparaginase, using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays. RESULTS: A significant approximately 3.5-fold lower TEL expression in t(12;21)+ compared with t(12;21)- ALL samples (P = 0.006) and normal controls (P = 0.004) was found. Expression of AML1 did not differ between t(12;21)+ and t(12;21)- ALL. However, AML1 expression in the leukemic cells was 2-fold higher compared with normal controls (P = 0.02). The TEL-AML1 fusion product was expressed in all t(12;21)+ cases, whereas the reciprocal fusion product AML1-TEL was expressed in only 76%. High expression levels of TEL-AML1 [hazard ratio (HR), 1.3; 95% confidence interval (95% CI), 1.10-1.57; P = 0.003], AML1-TEL (HR, 4.9; 95% CI, 1.99-12.40; P = 0.001) and AML1 (HR, 1.1; 95% CI, 1.03-1.22; P = 0.006) were associated with a poor long-term clinical outcome within t(12;21)+ ALL. Cellular drug resistance towards prednisolone, vincristine, and L-asparaginase could not explain this predictive value. Multivariate analysis including age and WBC showed that only high AML1-TEL expression is an independent poor prognostic factor in t(12;21)+ childhood ALL. CONCLUSION: High AML1-TEL expression is an independent poor prognostic factor in t(12;21)+ childhood ALL. 相似文献
18.
19.
Ebot Ojong Bassey Iya Jules Djeufouata Forwah Ndeh Augusta nsonwu Vigny Njongang Maisie Etukudo Chinyere Usoro Julie Ekpo 《African health sciences》2022,22(1):410
BackgroundAlthough an increasing access to ART in sub-Saharan Africa has made it possible for HIV/AIDS patients to live longer, clinicians managing such patients are faced with the challenge of drug-related metabolic complications.MethodsA cross -sectional study was carried out at the University of Calabar Teaching Hospital, Nigeria, on three groups of participants; namely HIV patients on ART, ART-naïve patients and HIV negative subjects (n =75). Demographic and anthropometric data were collected using a well-structured questionnaire while biochemical parameters were measured using colorimetric methods.ResultsThe highest prevalence of MS was associated with the HIV/AIDS patients on ART (i.e. 32.0 %, and 50.3% for NCEP-ATP III and IDF criteria respectively). Patients on ART had significant increases (p< 0.05) in waist to hip ratio, FPG, serum TG and LDL-c; and a significantly higher (p< 0.05) prevalence of hypertension, diabetes, low HDL-c and hypertriglyceridaemia compared to the ART-naïve patients. Low serum HDL-c was the most prevalent form of dyslipidaemia in all three groups and the most prevalent component of MS in HIV patients.ConclusionART increases the risk of MS and CVD. HIV/AIDS patients on ART should be advised on lifestyle modifications and undertake regular assessment of their cardiovascular risk factors. 相似文献
20.