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Chen Y, Qi A, Teng D, Li S, Yan Y, Hu S, Du X. Probiotics and synbiotics for preventing postoperative infectious complications in colorectal cancer patients: a systematic review and meta-analysis. Tech Coloproctol 2022; 26:425-436. [PMID: 35348943 DOI: 10.1007/s10151-022-02585-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2021] [Accepted: 01/22/2022] [Indexed: 02/06/2023]
Abstract
BACKGROUND The health benefits of probiotics and synbiotics in healthy adults are well established, but their role in preventing infectious complications after surgery for colorectal cancer remains controversial. The aim of this meta-analysis was to assess the impact of probiotics/synbiotics on the incidence of infectious complications in patients who had surgery for colorectal cancer. METHODS A comprehensive literature search of all randomized control trials (RCTs) was conducted using PubMed, Embase, World Health Organization (WHO) Global Index Medicus, WHO clinical trial registry, and Clinicaltrials.gov. Inclusion criteria included RCTs comparing the use of any strain or dose of a specified probiotic/synbiotic with placebo or a "standard care" control group. The incidence of postoperative infectious complications was analyzed. RESULTS Fourteen RCTs involving 1566 patients (502 receiving probiotics, 273 receiving synbiotics, and 791 receiving placebo) were analyzed. Overall, probiotic or synbiotic administration significantly reduced the risk of developing postoperative infectious complications by 37% (relative risk (RR) = 0.63, 95% confidence interval (CI) 0.54-0.74, p < 0.001). Furthermore, when considering the six different types of postoperative infectious complications (septicemia, incision infection, central line infection, pneumonia infection, urinary infection, and incidence of diarrhea), probiotic or synbiotic administration was beneficial in reducing the incidence of each one of them. The quality of evidence was listed below: incidence of diarrhea (high), septicemia (moderate), incision infection (moderate), pneumonia infection (moderate), urinary infection (moderate), and central line infection (low). However, for the main outcome of infectious complications, we found evidence of possible publication bias, although estimates still showed a reduction following trim-and-fill analysis (RR = 0.72, 95% CI 0.62-0.84, p < 0.001). CONCLUSIONS The use of probiotic/synbiotic supplementation is associated with a significant reduction in the risk of developing postoperative infectious complications in patients who had surgery for colorectal cancer. Additional studies are needed to confirm the findings due to publication bias and low quality of evidence.
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Affiliation(s)
- Y Chen
- Department of General Surgery, The First Medical Center, Chinese PLA General Hospital, Haidian, Beijing, 100853, China
| | - A Qi
- Department of General Surgery, The First Medical Center, Chinese PLA General Hospital, Haidian, Beijing, 100853, China
| | - D Teng
- Department of General Surgery, The First Medical Center, Chinese PLA General Hospital, Haidian, Beijing, 100853, China
| | - S Li
- Department of General Surgery, The First Medical Center, Chinese PLA General Hospital, Haidian, Beijing, 100853, China
| | - Y Yan
- Department of General Surgery, The First Medical Center, Chinese PLA General Hospital, Haidian, Beijing, 100853, China
| | - S Hu
- Department of General Surgery, The First Medical Center, Chinese PLA General Hospital, Haidian, Beijing, 100853, China
| | - X Du
- Department of General Surgery, The First Medical Center, Chinese PLA General Hospital, Haidian, Beijing, 100853, China.
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Zhang H, Yin F, Chen M, Qi A, Yang L, Cui W, Yang S, Wen G. [Predicting postoperative recurrence of stage Ⅰ-Ⅲ renal clear cell carcinoma based on preoperative CT radiomics feature nomogram]. Nan Fang Yi Ke Da Xue Xue Bao 2021; 41:1358-1365. [PMID: 34658350 DOI: 10.12122/j.issn.1673-4254.2021.09.10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
OBJECTIVE To explore the preoperative radiomics features (RFs) and construct a nomogram for predicting postoperative recurrence of stage Ⅰ-Ⅲ clear cell renal carcinoma (ccRCC). METHODS The clinicopathological data and preoperative enhanced CT images collected from 256 patients with ccRCC were used as the training dataset (175 patients) and test dataset (81 patients). The enhanced CT images of the tumor were segmented using ITK-SNAP software, and the RFs were extracted using the PyRadiomics computing platform. In the training dataset, the RFs were screened based on Lasso-CV algorithm, and the Rad_score was calculated. The Clinic factors were screened by univariate and multivariate logistic regression analysis of the clinical and pathological factors and CT characteristics. The Rad_score, Clinic、Rad_score + Clinic nomograms were constructed and verified using the test dataset. The performance, discrimination power and calibration of the nomograms were compared, and their clinical value was evaluated using decision curve analysis. RESULTS Six RFs were retained to calculate the Rad_score. The Clinic factors included Rad_score, KPS score, platelet, calcification and TNM clinical stage. In terms of discrimination, the Rad_score + Clinic nomogram showed better performance (AUC=0.84 for training set; AUC=0.85 for test set) than the Rad_score nomogram (AUC=0.78 for training set, P=0.029; AUC=0.77 for Test set, P=0.025) and Clinic nomogram (AUC=0.77 for training set, P=0.014; AUC=0.77 for test set, P=0.011). In terms of calibration, the P value for goodness of fit test of the Rad_score+Clinic nomogram was 0.065 for the training set and 0.628 for the test set. Decision curve analysis showed a greater clinical value of the Rad_score+Clinic nomogram with Rad_score than the Clinic nomogram without Rad_score. CONCLUSION The nomogram based on preoperative CT RFs has a high value for predicting postoperative recurrence of stage Ⅰ-Ⅲ ccRCC to facilitate individualized treatment of RCC.
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Affiliation(s)
- H Zhang
- PET/CT Center, First Affiliated Hospital of Shenzhen University, Shenzhen 518052, China.,Department of Imaging, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - F Yin
- Shenzhen University School of Information Engineering, Shenzhen 518052, China
| | - M Chen
- Department of Imaging, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - A Qi
- Department of Imaging, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - L Yang
- Department of Imaging, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - W Cui
- Department of Imaging, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - S Yang
- Department of Imaging, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - G Wen
- Department of Imaging, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
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Abstract
Background Syphilis is a multisystemic infection that causes a wide variety of symptoms and thus has been dubbed one of the great medical mimickers. Due to recent global re-emergence of syphilis, it has become important to recognize its various presentations. Relative to the kidney, syphilitic infections generally present themselves with nephrotic range proteinuria, and are most often associated with pathological features of a membranous glomerulonephritis with subepithelial immune complex deposition. However, other rare renal presentations have been reported. One of these includes a rapidly progressive glomerulonephritis picture. All described cases have been successfully resolved with the treatment of the underlying syphilis infection. Case presentation The patient was an elderly woman of Caribbean descent who presented with lower extremity weakness, anasarca and proteinuria, hematuria with progressive renal failure. On kidney biopsy, she was found to have a pauci-immune crescentic glomerulonephritis pattern and a concomitant acute tubulointerstitial nephritis. She had a positive Treponema pallidum particle agglutination test and a negative syphilis rapid plasma reagin test with clinical evidence of polyneuropathy suggestive chronic syphilis infection. Conclusion and discussion It is important in the context of pauci-immune crescentic glomerulonephritis to explore all differential diagnoses. Given the positive syphilis serologies, clinical context and presence of tubulointerstitial nephritis, she was determined to have syphilitic glomerulonephritis that resolved with a course of both penicillin and steroids.
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Affiliation(s)
- A Qi
- Department of Nephrology, St-Mary's Hospital, McGill University, 3830 av Lacombe, Qc, H3T 1M5, Montreal, Canada
| | - P O Fiset
- Department of Pathology, McGill University, Montreal, QC, Canada
| | - L Pilozzi-Edmonds
- Department of Nephrology, St-Mary's Hospital, McGill University, 3830 av Lacombe, Qc, H3T 1M5, Montreal, Canada.
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Wang K, Youngson E, Nikhanj A, Nguyen Q, Qi A, Thomas J, McAlister F, Oudit G. Differential trajectories in LVEF predicts divergent clinical outcomes in HFrEF patients. Eur Heart J 2020. [DOI: 10.1093/ehjci/ehaa946.0929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Background
Recovery or improvement in LVEF is observed in many HFrEF patients following optimal medical management and device therapies, but whether this reflects true myocardial recovery remains controversial and the significance of LVEF decompensation in relation to clinical outcomes is unclear.
Purpose
To elucidate clinical characteristics and assess prognosis of HFrEF patients with differential trajectories in LVEF.
Methods
Heart failure (HF) patients were enrolled in a prospective Heart Function registry from outpatient cardiology clinics at an academic institution between Feb 2018 and Nov 2019. Retrospective analysis was conducted on 2D-echocardiography (echo) performed between Jan 2009 and Nov 2019. In total, 590 patients met the inclusion criteria with ≥2 repeated echo evaluations separated by ≥1 year. Patient demographics and clinical characteristics at enrollment were collected through review of medical records. Cardiovascular and HF specific admissions were captured using the corresponding ICD-10-CA codes. During a median follow-up of 5.9 years (IQR: 3.1 to 8.5 years) from the first echo date, clinical outcomes were assessed through composite mortality and hospitalizations endpoints.
Results
We identified 3 independent cohorts with 279 patients having permanently reduced LVEF (<40%, HFrEF), 236 patients with recovered LVEF (>40% on serial evaluations, HFrecEF) and 75 patients with subsequent decompensation in LVEF (>40%, then <40%, HFdecEF) following initial recovery. Use of ACE inhibitors or ARBs (94% vs. 99% vs. 91%) and beta blockers (88% vs. 87% vs. 87%) at baseline echo was similar amongst HFrEF, HFrecEF and HFdecEF cohorts respectively. HFrecEF cohort had higher usage of MRA (55% vs. 65% vs. 44%, p=0.002) and diuretics (74% vs. 80% vs. 65%, p=0.026). HFdecEF cohort was characterized by a predominance of males (80% vs. 69% vs. 80%, p=0.01), and more patients with ischemic etiology (41% vs. 28% vs. 60%, p<0.001) compared with the HFrecEF cohort and resembled more closely to demographics of the HFrEF cohort. Median LVEF at baseline echo was similar across the cohorts. However, HFdecEF cohort had lower LV end-diastolic diameter (p<0.001), LV end-systolic diameter (p<0.001) and LV mass (p=0.01) compared with the HFrEF cohort sharing similarities with the HFrecEF cohort on baseline echo, suggesting lesser extent of adverse cardiac remodeling in both HFrecEF and HFdecEF cohorts initially. Over a median 5.9 years follow-up, HFdecEF and HFrEF patients had a significantly higher risk (compared to those with HFrecEF) of composite all-cause mortality with all-cause (80% vs. 75% vs. 57%, p=0.004), cardiovascular (48% vs. 50% vs. 29%, p=0.001) and HF hospitalizations (31% vs. 32% vs. 16%, p=0.004).
Conclusion
HFrEF patients who never recover their LVEF and patients with decompensation in LVEF following initial recovery represent a clinically higher risk group than patients who remained recovered during follow-up.
Funding Acknowledgement
Type of funding source: Foundation. Main funding source(s): University of Alberta Hospital Foundation, Canadian Institutes of Health Research
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Affiliation(s)
- K Wang
- Mazankowski Alberta Heart Institute, Edmonton, Canada
| | | | - A Nikhanj
- Mazankowski Alberta Heart Institute, Edmonton, Canada
| | - Q Nguyen
- Mazankowski Alberta Heart Institute, Edmonton, Canada
| | - A Qi
- Mazankowski Alberta Heart Institute, Edmonton, Canada
| | - J Thomas
- Mazankowski Alberta Heart Institute, Edmonton, Canada
| | - F McAlister
- Mazankowski Alberta Heart Institute, Edmonton, Canada
| | - G.Y Oudit
- Mazankowski Alberta Heart Institute, Edmonton, Canada
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5
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Lai X, Qi A, Liu Y, Mendoza LEDR, Liu Z, Lin Z, Khan MFR. Evaluating Inoculation Methods to Infect Sugar Beet with Fusarium oxysporum f. betae and F. secorum. Plant Dis 2020; 104:1312-1317. [PMID: 32181721 DOI: 10.1094/pdis-09-19-1895-re] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Minnesota and North Dakota combined contain 55% of the sugar beet production area in the United States, contributing to 49% of the nation's sugar beet production in 2018. Fusarium diseases caused by Fusarium oxysporum f. betae and F. secorum on sugar beet can cause significant reduction in both root yield and sucrose concentration and purity. The objective of this research was to identify an alternative artificial inoculation method to induce Fusarium diseases on sugar beet leaves and roots caused by both Fusarium spp. in greenhouse conditions to better aid in research efforts. We tested four inoculation methods, including barley to seed, barley to root, drenching, and cutting. and compared them with the conventional root-dipping inoculation method. The inoculation method of placing Fusarium-colonized barley seed close to sugar beet seed (barley to seed) caused levels of symptom severities on both leaves and roots similar to the root-dipping method. Because the traditional root-dipping method involves a laborious transplant process, use of infected barley seed as inoculum may serve as an alternative method in the evaluation of host resistance and pathogen virulence among Fusarium diseases by Fusarium spp. on sugar beet at the seed or seedling stage.
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Affiliation(s)
- X Lai
- Department of Plant Pathology, North Dakota State University, Fargo, ND 58108-6050, U.S.A
| | - A Qi
- School of Life and Medical Sciences, University of Hertfordshire, Hatfield, AL10 9AB, U.K
| | - Y Liu
- Department of Plant Pathology, North Dakota State University, Fargo, ND 58108-6050, U.S.A
| | - L E Del Río Mendoza
- Department of Plant Pathology, North Dakota State University, Fargo, ND 58108-6050, U.S.A
| | - Z Liu
- Department of Plant Pathology, North Dakota State University, Fargo, ND 58108-6050, U.S.A
| | - Z Lin
- Department of Agricultural and Biosystems Engineering, North Dakota State University, Fargo, ND 58108-6050, U.S.A
| | - M F R Khan
- Department of Plant Pathology, North Dakota State University, Fargo, ND 58108-6050, U.S.A
- University of Minnesota, St. Paul, MN, U.S.A
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Mitrousia GK, Huang YJ, Qi A, Sidique SNM, Fitt BDL. Effectiveness of Rlm7 resistance against Leptosphaeria maculans (phoma stem canker) in UK winter oilseed rape cultivars. Plant Pathol 2018; 67:1339-1353. [PMID: 30166691 PMCID: PMC6108410 DOI: 10.1111/ppa.12845] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The Rlm7 gene in Brassica napus is an important source of resistance for control of phoma stem canker on oilseed rape caused by the fungus Leptosphaeria maculans. This study shows the first report of L. maculans isolates virulent against Rlm7 in the UK. Leptosphaeria maculans isolates virulent against Rlm7 represented 3% of the pathogen population when cultivars with the Rlm7 gene represented 5% of the UK oilseed rape area in 2012/13. However, the Rlm7 gene has been widely used since then, representing >15% of the UK oilseed rape area in 2015/16. Winter oilseed rape field experiments included cultivars with the Rlm7 gene, with the Rlm4 gene or without Rlm genes and took place at five sites in the UK over four cropping seasons. An increase in phoma leaf spotting severity on Rlm7 cultivars in successive seasons was observed. Major resistance genes played a role in preventing severe phoma leaf spotting at the beginning of the cropping season and, in addition, quantitative resistance (QR) in the cultivars examined made an important contribution to control of phoma stem canker development at the end of the cropping season. Deployment of the Rlm7 resistance gene against L. maculans in cultivars with QR in combination with sustainable disease management practices will prolong the use of this gene for effective control of phoma stem canker epidemics.
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Affiliation(s)
- G. K. Mitrousia
- Centre for Agriculture, Food and Environmental ManagementUniversity of HertfordshireHatfieldHertfordshireAL10 9ABUK
| | - Y. J. Huang
- Centre for Agriculture, Food and Environmental ManagementUniversity of HertfordshireHatfieldHertfordshireAL10 9ABUK
| | - A. Qi
- Centre for Agriculture, Food and Environmental ManagementUniversity of HertfordshireHatfieldHertfordshireAL10 9ABUK
| | - S. N. M. Sidique
- Centre for Agriculture, Food and Environmental ManagementUniversity of HertfordshireHatfieldHertfordshireAL10 9ABUK
- Present address:
Laboratory for Pest, Disease and Microbial Biotechnology (LAPDiM)School of Food Science and TechnologyUniversiti Malaysia TerengganuKuala Nerus21030Malaysia
| | - B. D. L. Fitt
- Centre for Agriculture, Food and Environmental ManagementUniversity of HertfordshireHatfieldHertfordshireAL10 9ABUK
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7
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Qi A, Lin C, Zhou A, Du J, Jia X, Sun L, Zhang G, Zhang L, Liu M. Negative emotions affect postoperative scores for evaluating functional knee recovery and quality of life after total knee replacement. ACTA ACUST UNITED AC 2016; 49:e4616. [PMID: 26577843 PMCID: PMC4678652 DOI: 10.1590/1414-431x20154616] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 06/24/2015] [Indexed: 12/17/2022]
Abstract
This study aimed to determine whether psychological factors affect health-related
quality of life (HRQL) and recovery of knee function in total knee replacement (TKR)
patients. A total of 119 TKR patients (male: 38; female: 81) completed the Beck
Anxiety Inventory (BAI), Beck Depression Inventory (BDI), State Trait Anxiety
Inventory (STAI), Eysenck Personality Questionnaire-revised (EPQR-S), Knee Society
Score (KSS), and HRQL (SF-36). At 1 and 6 months after surgery, anxiety, depression,
and KSS scores in TKR patients were significantly better compared with those
preoperatively (P<0.05). SF-36 scores at the sixth month after surgery were
significantly improved compared with preoperative scores (P<0.001). Preoperative
Physical Component Summary Scale (PCS) and Mental Component Summary Scale (MCS)
scores were negatively associated with extraversion (E score) (B=-0.986 and -0.967,
respectively, both P<0.05). Postoperative PCS and State Anxiety Inventory (SAI)
scores were negatively associated with neuroticism (N score; B=-0.137 and -0.991,
respectively, both P<0.05). Postoperative MCS, SAI, Trait Anxiety Inventory (TAI),
and BAI scores were also negatively associated with the N score (B=-0.367, -0.107,
-0.281, and -0.851, respectively, all P<0.05). The KSS function score at the sixth
month after surgery was negatively associated with TAI and N scores (B=-0.315 and
-0.532, respectively, both P<0.05), but positively associated with the E score
(B=0.215, P<0.05). The postoperative KSS joint score was positively associated
with postoperative PCS (B=0.356, P<0.05). In conclusion, for TKR patients, the
scores used for evaluating recovery of knee function and HRQL after 6 months are
inversely associated with the presence of negative emotions.
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Affiliation(s)
- A Qi
- Department of Nursing, Laiwu People's Hospital, Laiwu, China
| | - C Lin
- Department of Cardiology, Laiwu People's Hospital, Laiwu, China
| | - A Zhou
- The First Ward of the Surgical Department, Laiwu People's Hospital, Laiwu, China
| | - J Du
- Laiwu People's Hospital, Department of Internal Medicine, Branch of Laiwu People's Hospital, Laiwu, China
| | - X Jia
- Department of Nursing, Laiwu People's Hospital, Laiwu, China
| | - L Sun
- Department of Nursing, Laiwu People's Hospital, Laiwu, China
| | - G Zhang
- Department of Nursing, Laiwu People's Hospital, Laiwu, China
| | - L Zhang
- China Medical University, Department of Traumatic Orthopedics, Shengjing Hospital, Shenyang, China
| | - M Liu
- China Medical University, Department of Traumatic Orthopedics, Shengjing Hospital, Shenyang, China
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8
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Gemingguli M, Iskhan KR, Li Y, Qi A, Wunirifu W, Ding LY, Wumaierjiang A. Genetic diversity and population structure of Kazakh horses (Equus caballus) inferred from mtDNA sequences. Genet Mol Res 2016; 15:gmr8618. [PMID: 27808359 DOI: 10.4238/gmr.15048618] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The Kazakh horse is an important old horse breed in Xinjiang. They have contributed greatly to the breeding and improvement of other local horse breeds, yet their genetic diversity and population structure are not well understood. In the present study, we evaluated the genetic diversity of Kazakh horses and their relationship with other horse breeds using the mtDNA D-loop region, Cyt b gene, and a DNA fragment (nps 7974-9963, containing COX3, tRNA-Gly, ND3, and tRNA-Arg). A total of 130 Kazakh horses from 8 populations in China and Kazakhstan were analyzed. A total of 88 haplotypes (haplotype diversity: 0.9895) were identified, in which 3 haplotypes were shared by groups in the two countries. In a median-joining network, 6 haplogroups were found, in which most haplogroups included haplotypes from different populations. Neighbor-joining analysis revealed similar results in that haplotypes in different populations were admixed in most of the 6 clusters. In conclusion, a high level of genetic diversity was found in the Kazakh horses. However, no clear correspondence between haplogroups and geographic origin and no significant differentiation between populations in the two countries were observed. This might have resulted from the frequent contact between the two countries through the Silk Road in the past, or due to long-term outcrossing and hybridization with the introduced horses.
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Affiliation(s)
- M Gemingguli
- College of Animal Science, Tarim University, Alar, Xinjiang, China
| | - K R Iskhan
- Department of Animal Science, Kazakhstan National Agrarian University, Almaty, The Republic of Kazakhstan
| | - Y Li
- Institute of Arid Ecology and Environment, Xinjiang University, Urumqi, China
| | - A Qi
- Genomics Laboratory of Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, China
| | - W Wunirifu
- College of Animal Science and Veterinary, Inner Mongolia Agricultural University, Huhhot, China
| | - L Y Ding
- College of Animal Science, Tarim University, Alar, Xinjiang, China
| | - A Wumaierjiang
- College of Animal Science, Tarim University, Alar, Xinjiang, China
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9
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Alhasan L, Qi A, Al-Abboodi A, Rezk A, Chan PP, Iliescu C, Yeo LY. Rapid Enhancement of Cellular Spheroid Assembly by Acoustically Driven Microcentrifugation. ACS Biomater Sci Eng 2016; 2:1013-1022. [DOI: 10.1021/acsbiomaterials.6b00144] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Layla Alhasan
- Biotechnology & Biological Sciences, School of Applied Science, RMIT University, Melbourne, Victoria 3000, Australia
| | - Aisha Qi
- Micro/Nanophysics
Research Laboratory, RMIT University, Melbourne, Victoria 3000, Australia
| | - Aswan Al-Abboodi
- Department
of Chemical Engineering, Monash University, Clayton, Victoria 3800, Australia
| | - Amgad Rezk
- Micro/Nanophysics
Research Laboratory, RMIT University, Melbourne, Victoria 3000, Australia
| | - Peggy P.Y. Chan
- Micro/Nanophysics
Research Laboratory, RMIT University, Melbourne, Victoria 3000, Australia
- Department
of Biomedical Engineering, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia
| | - Ciprian Iliescu
- Institute
of Bioengineering and Nanotechnology, A*STAR, Singapore 138669, Singapore
| | - Leslie Y. Yeo
- Micro/Nanophysics
Research Laboratory, RMIT University, Melbourne, Victoria 3000, Australia
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10
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Alhasan L, Qi A, Rezk AR, Yeo LY, Chan PPY. Assessment of the potential of a high frequency acoustomicrofluidic nebulisation platform for inhaled stem cell therapy. Integr Biol (Camb) 2016; 8:12-20. [DOI: 10.1039/c5ib00206k] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
This study demonstrates the use of a novel high frequency acoustic nebulisation platform as an effective aerosolisation technique for inhaled mesenchymal stem cell (MSC) therapy.
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Affiliation(s)
- Layla Alhasan
- Department of Biotechnology & Biological Science
- RMIT University
- Melbourne
- Australia
- Micro/Nanophysics Research Laboratory
| | - Aisha Qi
- Micro/Nanophysics Research Laboratory
- RMIT University
- Melbourne
- Australia
| | - Amgad R. Rezk
- Micro/Nanophysics Research Laboratory
- RMIT University
- Melbourne
- Australia
| | - Leslie Y. Yeo
- Micro/Nanophysics Research Laboratory
- RMIT University
- Melbourne
- Australia
| | - Peggy P. Y. Chan
- Micro/Nanophysics Research Laboratory
- RMIT University
- Melbourne
- Australia
- Department of Biomedical Engineering
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11
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Cortez-Jugo C, Qi A, Rajapaksa A, Friend JR, Yeo LY. Pulmonary monoclonal antibody delivery via a portable microfluidic nebulization platform. Biomicrofluidics 2015; 9:052603. [PMID: 25945147 PMCID: PMC4393410 DOI: 10.1063/1.4917181] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 03/27/2015] [Indexed: 05/06/2023]
Abstract
Nebulizers have considerable advantages over conventional inhalers for pulmonary drug administration, particularly because they do not require coordinated breath actuation to generate and deliver the aerosols. Nevertheless, besides being less amenable to miniaturization and hence portability, some nebulizers are prone to denature macromolecular drugs due to the large forces generated during aerosolization. Here, we demonstrate a novel portable acoustomicrofluidic device capable of nebulizing epidermal growth factor receptor (EGFR) monoclonal antibodies into a fine aerosol mist with a mass median aerodynamic diameter of approximately 1.1 μm, optimal for deep lung deposition via inhalation. The nebulized monoclonal antibodies were tested for their stability, immunoactivity, and pharmacological properties, which confirmed that nebulization did not cause significant degradation of the antibody. In particular, flow cytometry demonstrated that the antigen binding capability of the antibody is retained and able to reduce phosphorylation in cells overexpressing the EGFR, indicating that the aerosols generated by the device were loaded with stable and active monoclonal antibodies. The delivery of antibodies via inhalation, particularly for the treatment of lung cancer, is thus expected to enhance the efficacy of this protein therapeutic by increasing the local concentration where they are needed.
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Affiliation(s)
| | - Aisha Qi
- Micro/Nanophysics Research Laboratory, RMIT University , Melbourne, Victoria 3001, Australia
| | - Anushi Rajapaksa
- Murdoch Children's Research Institute , Parkville, Victoria 3052, Australia
| | - James R Friend
- Micro/Nanophysics Research Laboratory, RMIT University , Melbourne, Victoria 3001, Australia
| | - Leslie Y Yeo
- Micro/Nanophysics Research Laboratory, RMIT University , Melbourne, Victoria 3001, Australia
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Rajapaksa A, Qi A, Yeo LY, Coppel R, Friend JR. Enabling practical surface acoustic wave nebulizer drug delivery via amplitude modulation. Lab Chip 2014; 14:1858-65. [PMID: 24740643 DOI: 10.1039/c4lc00232f] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
A practical, commercially viable microfluidic device relies upon the miniaturization and integration of all its components--including pumps, circuitry, and power supply--onto a chip-based platform. Surface acoustic waves (SAW) have become popular in microfluidic manipulation, in solving the problems of microfluidic manipulation, but practical applications employing SAW still require more power than available via a battery. Introducing amplitude modulation at 0.5-40 kHz in SAW nebulization, which requires the highest energy input levels of all known SAW microfluidic processes, halves the power required to 1.5 W even while including the power in the sidebands, suitable for small lithium ion batteries, and maintains the nebulization rate, size, and size distributions vital to drug inhalation therapeutics. This simple yet effective means to enable an integrated SAW microfluidics device for nebulization exploits the relatively slow hydrodynamics and is furthermore shown to deliver shear-sensitive biomolecules--plasmid DNA and antibodies as exemplars of future pulmonary gene and vaccination therapies--undamaged in the nebulized mist. Altogether, the approach demonstrates a means to offer truly micro-scale microfluidics devices in a handheld, battery powered SAW nebulization device.
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Affiliation(s)
- Anushi Rajapaksa
- Micro/Nanophysics Research Laboratory, Monash University, Clayton, VIC 3800 Australia
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Rajapaksa AE, Ho JJ, Qi A, Bischof R, Nguyen TH, Tate M, Piedrafita D, McIntosh MP, Yeo LY, Meeusen E, Coppel RL, Friend JR. Effective pulmonary delivery of an aerosolized plasmid DNA vaccine via surface acoustic wave nebulization. Respir Res 2014; 15:60. [PMID: 24884387 PMCID: PMC4040411 DOI: 10.1186/1465-9921-15-60] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Accepted: 04/25/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Pulmonary-delivered gene therapy promises to mitigate vaccine safety issues and reduce the need for needles and skilled personnel to use them. While plasmid DNA (pDNA) offers a rapid route to vaccine production without side effects or reliance on cold chain storage, its delivery to the lung has proved challenging. Conventional methods, including jet and ultrasonic nebulizers, fail to deliver large biomolecules like pDNA intact due to the shear and cavitational stresses present during nebulization. METHODS In vitro structural analysis followed by in vivo protein expression studies served in assessing the integrity of the pDNA subjected to surface acoustic wave (SAW) nebulisation. In vivo immunization trials were then carried out in rats using SAW nebulized pDNA (influenza A, human hemagglutinin H1N1) condensate delivered via intratracheal instillation. Finally, in vivo pulmonary vaccinations using pDNA for influenza was nebulized and delivered via a respirator to sheep. RESULTS The SAW nebulizer was effective at generating pDNA aerosols with sizes optimal for deep lung delivery. Successful gene expression was observed in mouse lung epithelial cells, when SAW-nebulized pDNA was delivered to male Swiss mice via intratracheal instillation. Effective systemic and mucosal antibody responses were found in rats via post-nebulized, condensed fluid instillation. Significantly, we demonstrated the suitability of the SAW nebulizer to administer unprotected pDNA encoding an influenza A virus surface glycoprotein to respirated sheep via aerosolized inhalation. CONCLUSION Given the difficulty of inducing functional antibody responses for DNA vaccination in large animals, we report here the first instance of successful aerosolized inhalation delivery of a pDNA vaccine in a large animal model relevant to human lung development, structure, physiology, and disease, using a novel, low-power (<1 W) surface acoustic wave (SAW) hand-held nebulizer to produce droplets of pDNA with a size range suitable for delivery to the lower respiratory airways.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | - James R Friend
- RMIT University, Micro Nano Research Facility, 124 La Trobe Street, 3000 Melbourne, Australia.
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Qi A, Hoo SP, Friend J, Yeo L, Yue Z, Chan PPY. Hydroxypropyl cellulose methacrylate as a photo-patternable and biodegradable hybrid paper substrate for cell culture and other bioapplications. Adv Healthc Mater 2014; 3:543-54. [PMID: 24039172 DOI: 10.1002/adhm.201300155] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2013] [Indexed: 12/22/2022]
Abstract
In addition to the choice of appropriate material properties of the tissue construct to be used, such as its biocompatibility, biodegradability, cytocompatibility, and mechanical rigidity, the ability to incorporate microarchitectural patterns in the construct to mimic that found in the cellular microenvironment is an important consideration in tissue engineering and regenerative medicine. Both these issues are addressed by demonstrating a method for preparing biodegradable and photo-patternable constructs, where modified cellulose is cross-linked to form an insoluble structure in an aqueous environment. Specifically, hydroxypropyl cellulose (HPC) is rendered photocrosslinkable by grafting with methylacrylic anhydride, whose linkages also render the cross-linked construct hydrolytically degradable. The HPC is then cross-linked via a photolithography-based fabrication process. The feasibility of functionalizing these HPC structures with biochemical cues is verified post-fabrication, and shown to facilitate the adhesion of mesenchymal progenitor cells. The HPC constructs are shown to be biocompatible and hydrolytically degradable, thus enabling cell proliferation and cell migration, and therefore constituting an ideal candidate for long-term cell culture and implantable tissue scaffold applications. In addition, the potential of the HPC structure is demonstrated as an alternative substrate to paper microfluidic diagnostic devices for protein and cell assays.
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Affiliation(s)
- Aisha Qi
- Micro/Nanophysics Research Laboratory; RMIT University; Melbourne, VIC 3000, Australia Melbourne Centre for Nanofabrication Clayton VIC 3168 Australia
| | - Siew Pei Hoo
- Department of Chemical Engineering; Monash University; Clayton VIC 3800 Australia
| | - James Friend
- Micro/Nanophysics Research Laboratory; RMIT University; Melbourne, VIC 3000, Australia Melbourne Centre for Nanofabrication Clayton VIC 3168 Australia
| | - Leslie Yeo
- Micro/Nanophysics Research Laboratory; RMIT University; Melbourne, VIC 3000, Australia Melbourne Centre for Nanofabrication Clayton VIC 3168 Australia
| | - Zhilian Yue
- ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research; Institute University of Wollongong; Australia
| | - Peggy P. Y. Chan
- Micro/Nanophysics Research Laboratory; RMIT University; Melbourne, VIC 3000, Australia Melbourne Centre for Nanofabrication Clayton VIC 3168 Australia
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Burlakoti P, Rivera V, Secor GA, Qi A, Rio-Mendoza LED, Khan MFR. Comparative Pathogenicity and Virulence of Fusarium Species on Sugar Beet. Plant Dis 2012; 96:1291-1296. [PMID: 30727152 DOI: 10.1094/pdis-10-11-0908-re] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In all, 98 isolates of three Fusarium spp. (18 Fusarium oxysporum, 30 F. graminearum, and 50 Fusarium sp. nov.) obtained from sugar beet in Minnesota were characterized for pathogenicity and virulence on sugar beet in the greenhouse by a bare-root inoculation method. Among the 98 isolates tested, 80% of isolates were pathogenic: 83% of the F. oxysporum isolates, 57% of the F. graminearum isolates, and 92% of the Fusarium sp. nov. isolates. Symptoms varied from slight to moderate wilting of the foliage, interveinal chlorosis and necrosis, and vascular discoloration of the taproot without any external root symptoms. Among the pathogenic isolates, 14% were highly virulent and 12% were moderately virulent. Most of the highly virulent isolates (91%) and moderately virulent isolates (89%) were Fusarium sp. nov. All pathogenic isolates of F. graminearum and most pathogenic isolates (87%) of F. oxysporum were less virulent. In general, more-virulent isolates induced first foliar symptoms earlier compared with less-virulent isolates. This study indicates that both F. oxysporum and Fusarium sp. nov. should be used in greenhouse and be present in field studies used for screening and developing sugar beet cultivars resistant to Fusarium yellows complex for Minnesota and North Dakota.
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Affiliation(s)
- Pragyan Burlakoti
- Department of Plant Pathology, North Dakota State University, Fargo 58105
| | - V Rivera
- Department of Plant Pathology, North Dakota State University, Fargo 58105
| | - G A Secor
- Department of Plant Pathology, North Dakota State University, Fargo 58105
| | - A Qi
- Broom's Barn Research Center, Higham, Bury St. Edmunds, Suffolk, IP28 6 NP, England
| | | | - Mohamed F R Khan
- Department of Plant Pathology, North Dakota State University, and University of Minnesota
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Abstract
Paper-based microfluidics has recently received considerable interest due to their ease and low cost, making them extremely attractive as point-of-care diagnostic devices. The incorporation of basic fluid actuation and manipulation schemes on paper substrates, however, afford the possibility to extend the functionality of this simple technology to a much wider range of typical lab-on-a-chip operations, given its considerable advantages in terms of cost, size and integrability over conventional microfluidic substrates. We present a convective actuation mechanism in a simple paper-based microfluidic device using surface acoustic waves to drive mixing. Employing a Y-channel structure patterned onto paper, the mixing induced by the 30 MHz acoustic waves is shown to be consistent and rapid, overcoming several limitations associated with its capillary-driven passive mixing counterpart wherein irreproducibilities and nonuniformities are often encountered in the mixing along the channel--capillary-driven passive mixing offers only poor control, is strongly dependent on the paper's texture and fibre alignment, and permits backflow, all due to the scale of the fibres being significant in comparison to the length scales of the features in a microfluidic system. Using a novel hue-based colourimetric technique, the mixing speed and efficiency is compared between the two methods, and used to assess the effects of changing the input power, channel tortuousity and fibre/flow alignment for the acoustically-driven mixing. The hue-based technique offers several advantages over grayscale pixel intensity analysis techniques in facilitating quantification without limitations on the colour contrast of the samples, and can be used, for example, for quantification in on-chip immunochromatographic assays.
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Affiliation(s)
- Amgad R Rezk
- Micro/Nanophysics Research Laboratory, School of Electrical & Computer Engineering, RMIT University, Melbourne, VIC 3000, Australia
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Qi A, Chan P, Ho J, Rajapaksa A, Friend J, Yeo L. Template-free synthesis and encapsulation technique for layer-by-layer polymer nanocarrier fabrication. ACS Nano 2011; 5:9583-9591. [PMID: 22059733 DOI: 10.1021/nn202833n] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The encapsulation of therapeutic molecules within multiple layers of biocompatible and biodegradable polymeric excipients allows exquisite design of their release profile, to the extent the drug can be selectively delivered to a specific target location in vivo. Here, we develop a novel technique for the assembly of multilayer polyelectrolyte nanocarriers based on surface acoustic wave atomization as a rapid and efficient alternative to conventional layer-by-layer assembly, which requires the use of a sacrificial colloidal template over which consecutive polyelectrolyte layers are deposited. Polymer nanocarriers are synthesized by atomizing a polymer solution and suspending them within a complementary polymer solution of opposite charge subsequent to their solidification in-flight as the solvent evaporates; reatomizing this suspension produces nanocarriers with a layer of the second polymer deposited over the initial polymer core. Successive atomization-suspension layering steps can then be repeated to produce as many additional layers as desired. Specifically, we synthesize nanocarriers comprising two and three, and up to eight, alternating layers of chitosan (or polyethyleneimine) and carboxymethyl cellulose within which plasmid DNA is encapsulated and show in vitro DNA release profiles over several days. Evidence that the plasmid's viability is preserved and hence the potential of the technique for gene delivery is illustrated through efficient in vitro transfection of the encapsulated plasmid in human mesenchymal progenitor and COS-7 cells.
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Affiliation(s)
- Aisha Qi
- Micro/Nanophysics Research Laboratory, RMIT University, Melbourne, VIC 3001, Australia
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Qi A, Tung S, Chakrabarti S, Flavelle S, McIlroy C, Hahn E, Yeung-Lai-Wah J, Kerr C. 639 Do types of appropriate therapies affect prognosis in patients receiving implantable cardioverters defibrillators? Can J Cardiol 2011. [DOI: 10.1016/j.cjca.2011.07.530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022] Open
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Qi A, Yeo L, Friend J, Ho J. The extraction of liquid, protein molecules and yeast cells from paper through surface acoustic wave atomization. Lab Chip 2010; 10:470-6. [PMID: 20126687 DOI: 10.1039/b915833b] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Paper has been proposed as an inexpensive and versatile carrier for microfluidics devices with abilities well beyond simple capillary action for pregnancy tests and the like. Unlike standard microfluidics devices, extracting a fluid from the paper is a challenge and a drawback to its broader use. Here, we extract fluid from narrow paper strips using surface acoustic wave (SAW) irradiation that subsequently atomizes the extracted fluid into a monodisperse aerosol for use in mass spectroscopy, medical diagnostics, and drug delivery applications. Two protein molecules, ovalbumin and bovine serum albumin (BSA), have been preserved in paper and then extracted using atomized mist through SAW excitation; protein electrophoresis shows there is less than 1% degradation of either protein molecule in this process. Finally, a solution of live yeast cells was infused into paper, which was subsequently dried for preservation then remoistened to extract the cells via SAW atomization, yielding live cells at the completion of the process. The successful preservation and extraction of fluids, proteins and yeast cells significantly expands the usefulness of paper in microfluidics.
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Affiliation(s)
- Aisha Qi
- MicroNanophysics Research Laboratory, Department of Mechanical and Aerospace Engineering, Monash University, Melbourne, VIC 3800, Australia
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20
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Qi A, Wuliji T, Zhang Y. 395 OVINE SPERMATOGONIA ISOLATION AND IN VITRO GROWTH ASSAY. Reprod Fertil Dev 2010. [DOI: 10.1071/rdv22n1ab395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Spermatogonia, as adult stem cells from the male reproductive system, are attracting strong interest from those studying male reproductive gamete preservation and developing new approaches in transgenic animals. Protein gene product 9.5 (PGP9.5) is a marker of sheep spermatogonia, which has been validated by J. R. Rodriguez-Sosa et al. (2006).The objective of this study was to develop an in vitro culture system for spermatogonial growth. Twenty 2- to 3-month-old rams were randomly selected at a local slaughter house for testicular tissue collection. Two-step enzymatic digestion methods were used for spermatogonia isolation from seminiferous tubules. In brief, mechanically isolated seminiferous tubules from testicular tissue were incubated in 1:1 1 mg mL-1 collagenase and hyaluronidase with 5 μg mL-1 DNase I for 20 min at 37°C. Most of the surrounding interstitial cells will fall off from seminiferous tubules by slightly pipetting. Seminiferous tubules were from cell suspensions after natural sedimentation in PBS and then were digested in 0.25% trypsin + 0.04% EDTAfor 5 to 7 min at 37°C to disassociate tubules into single cells. Data were analyzed with ANOVA procedures. Means of 5 specimens were presented. Of the total isolated cells, 19.7 ± 5.3% were identified as PGP9.5+cells, and 23.8 ± 3.6% were identified as c-kit+ cells. C-kit, the transmembrane tyrosine kinase receptor for stem cell factor, has been identified, which is expressed and functional in differentiating A1-A4 spermatogonia but not in spermatogonial stem cells (OhtaH2000). For in vitro culture of spermatogonia, DMEM supplemented with 1X ITS (insulin, transferrin, selenium), 100 μM β-mercaptoethano, 6 mM L-Glutamine, and 1X nonessential amino acids were used as basic culture medium. We have found that in primary spermatogonia culture, cells cultured together with testis somatic cells (sertoli cells) in basic medium supplied with 2.5% fetal bovine serum (FBS) were much more efficient than culturing with a supplement of 10% FBS. In primary culture, growing round-shaped cell colonies were visible from Day 5 in basic culture medium. In subculture, colonies were enzymically digested into smaller pieces from Day 8 to 10 and then placed onto mouse embryonic fibroblasts feeder layer in 2.5% FBS basic medium with the addition of 100 ng mL-1 glial cell-derived neurotropic factor, 10 ng mL-1 leukemia inhibitory factor, and 10 ng mL-1 basic fibroblast growth factor. PGP9.5+ spermatogonia cell colonies maintained their normal round shape until 4 to 5 passages. However, in subsequent passages, the colonies became flattened and cells gradually lost their interconnection and the growth pattern present in the early passages. Also in subsequent passages, cells began expressing more C-kit than PGP9.5. In conclusion, PGP9.5+ spermatogonia were successfully isolated from 2- to 3-month-old ram testis, and PGP 9.5 cell colonies were maintained and proliferated in the in vitro culture system up to 2 months.
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Qi A, Friend JR, Yeo LY, Morton DAV, McIntosh MP, Spiccia L. Miniature inhalation therapy platform using surface acoustic wave microfluidic atomization. Lab Chip 2009; 9:2184-93. [PMID: 19606295 DOI: 10.1039/b903575c] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Pulmonary drug administration requires direct delivery of drug formulations into the lower pulmonary tract and alveoli of the lung in the form of inhaled particles or droplets, providing a distinct advantage over other methods for the treatment of respiratory diseases: the drug can be delivered directly to the site of inflammation, thus reducing the need for systemic exposure and the possibility of adverse effects. However, it is difficult to produce droplets of a drug solution within a narrow monodisperse size range (1-10 microm) needed for deposition in the lower pulmonary tract and alveoli. Here, we demonstrate the use of surface acoustic wave microfluidic atomization as an efficient means to generate appropriate aerosols containing a model drug, the short-acting beta2 agonist salbutamol, for the treatment of asthma. The mean aerosol diameter produced, 2.84+/-0.14 microm, lies well within the optimum size range, confirmed by a twin-stage impinger lung model, demonstrating that approximately 70 to 80% of the drug supplied to the atomizer is deposited within the lung. Our preliminary study explores how to control the aerosol diameter and lung delivery efficiency through the surface tension, viscosity, and input power, and also indicates which factors are irrelevant-like the fluid density. Even over a modest power range of 1-1.5 W, SAW atomization provides a viable and efficient generic nebulization platform for the delivery of drugs via the pulmonary route for the treatment of various diseases. The control offered over the aerosol size, low power requirements, high delivery efficiency, and the miniaturization of the system together suggest the proposed platform represents an attractive alternative to current nebulizers compatible with microfluidic technologies.
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Affiliation(s)
- Aisha Qi
- Micro/Nanophysics Research Laboratory, Department of Chemistry, Monash University, Clayton, VIC 3800, Australia
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Khan J, Qi A, Khan MFR. Fluctuations in number of Cercospora beticola conidia in relationship to environment and disease severity in sugar beet. Phytopathology 2009; 99:796-801. [PMID: 19522577 DOI: 10.1094/phyto-99-7-0796] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Cercospora leaf spot, caused by Cercospora beticola, is the most damaging foliar disease of sugar beet in Minnesota (MN) and North Dakota (ND). Research was conducted to characterize the temporal progression of aerial concentration of C. beticola conidia in association with the environment and disease severity in sugar beet. In 2003 and 2004, volumetric spore traps were placed within inoculated sugar beet plots to determine daily dispersal of conidia at Breckenridge, MN, and St. Thomas, ND. Plots were rated weekly for disease severity. At both locations, conidia were first collected in early July 2003 and late June in 2004. Peaks of conidia per cubic meter of air were observed with maxima in late August 2003 and in early September 2004 at both locations. Peaks of airborne conidium concentration were significantly correlated with the average temperature of daily hours when relative humidity was greater than 87%. Weekly mean hourly conidia per cubic meter of air was significantly (P < 0.01) associated with disease severity during both years and across locations. This study showed that C. beticola conidial numbers may be used to estimate potential disease severity that, with further research, could be incorporated in a disease forecasting model to rationalize Cercospora leaf spot management.
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Affiliation(s)
- J Khan
- Department of Plant Pathology, North Dakota State University, Fargo, ND 58105, USA
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Abstract
Sugar beet is spring-sown for sugar production in most sugar beet-growing countries. It is grown as a vegetative crop and it accumulates yield (sugar) from very early in its growth cycle. As long as the sugar beet plants do not flower, the sugar accumulation period is indefinite and yield continues to increase. This paper reviews the success of the sugar beet crop in capturing and using solar radiation, water and mineral nitrogen resources. The prospects for improved resource capture and therefore increased sugar yield are also considered, particularly the potential to increase solar radiation interception in the future by sowing the crop in the autumn.
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Affiliation(s)
- K W Jaggard
- Rothamsted Research, Broom's Barn Research Centre, Higham, Bury St Edmunds, Suffolk IP28 6NP, UK.
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Eisenmenger W, Du XX, Tang C, Zhao S, Wang Y, Rong F, Dai D, Guan M, Qi A. The first clinical results of "wide-focus and low-pressure" ESWL. Ultrasound Med Biol 2002; 28:769-774. [PMID: 12113789 DOI: 10.1016/s0301-5629(02)00507-0] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A clinical study of the concept "wide-focus and low-pressure" extracorporal shock-wave lithotripsy (ESWL) was performed in a scientific cooperation between the Physical Institute of the University of Stuttgart and the Xixin Medical Instruments Co. Ltd. in Wuxian-Suzhou, China. In this cooperation, self-focusing electromagnetic shock-wave generator systems from the University of Stuttgart were integrated into Xixin lithotripters and installed in seven hospitals in China. A total of 297 detailed patient protocols revealed an average of 1532 shock pulses for successful treatment with no necessity for pain medication and auxiliary measures, and a stone-free rate of 86% after a follow-up of 3 months. These results are discussed in terms of the wide-focus low-pressure conditions and the mechanism of binary fragmentation by squeezing.
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Affiliation(s)
- W Eisenmenger
- Physical Institute, University of Stuttgart, Stuttgart, Germany.
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Abstract
This report describes a 33-year-old patient with arrhythmogenic right ventricular (RV) dysplasia who had a dual chamber pacemaker implanted at age 23 years for drug-induced bradycardia. Pacing was continued after right ventricular free-wall disconnection (RVFWD) at age 24 years. Her pacemaker was not replaced after battery depletion 7 years later. She presented the following year in severe right-sided heart failure. Her old pacemaker generator was replaced. This was followed by rapid resolution of her clinical failure and return to a full, active, physical lifestyle. This observation suggests the potential benefit of dual chamber pacing in patients with RV dysplasia after RVFWD.
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Affiliation(s)
- C Tang
- Department of Medicine, University of British Columbia, Vancouver, Canada
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Abstract
A new type of endocardial bipolar pacing lead has been designed to overcome the potential drawbacks of the conventional coaxial bipolar pacing lead. We prospectively evaluated the new co-radial bipolar pacing leads (Intermedics Thin-Line), which are thinner (5 Fr vs 6-8 Fr) than standard coaxial bipolar leads. X-ray visibility and lead handling were subjectively assessed (excellent, good, adequate, or poor) at implant; lead impedance, sensitivity threshold, and pacing threshold were measured at implant, then at 1, 3, 6, 12, and 18 months. The results were as follows: 103 patients (51 M; age 63.8 +/- 17.4 years) received 71 atrial (A) and 89 ventricular (V) leads. X-ray visibility was excellent in 59/103; good in 23/103; adequate in 11/103; and poor in 10/103. Overall handling was excellent in 56/71 A and 69/89 V; good in 11/71 A and 18/89 V; adequate in 3/71 A and 1/89 V; poor in 1/71 A and 1/89 V. There were two perioperative complications. At implant: impedance in A and V were 370.1 +/- 74.7 and 501.5 +/- 124.4 omega, sensing thresholds in A and V were 3.0 +/- 1.5 and 9.9 +/- 5.0 mV, pacing thresholds at 0.45 ms in A and V were 0.59 +/- 0.21 and 0.41 +/- 0.15 volt, respectively. At 1, 3, 6, 12, and 18 months of follow-up: no pacing lead related complications were reported; pacing lead characteristics remained outstanding and stable. This new lead appears to have significant clinical advantages over the conventional coaxial bipolar pacing lead. Long-term follow-up is required to confirm its reliability and chronic performance characteristics.
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Affiliation(s)
- C Tang
- Department of Medicine, University of British Columbia, Vancouver Hospital and Health Sciences Centre (UBC and Oak Street Sites), Canada
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Qi A, Tang C, Yeung-Lai-Wah JA, Kerr CR. Characteristics of restitution kinetics in repolarization of rabbit atrium. Can J Physiol Pharmacol 1997. [DOI: 10.1139/y97-038] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Abstract
The study was designed to characterize restitution kinetics in atrial repolarization of rabbits and to examine effects of K+ or Ca2+ channel blockers on restitution. Action potentials were recorded from rabbit atrial tissue. Restitution curves of phase I amplitude and action potential duration at 50 and 90% repolarization (APD50, APD90) were defined at a basic cycle length of 0.5 s during control and with interventions. Restitution of phase I amplitude had a monoexponential function with a time constant of 2.8 +/- 0.2 s. The curves of APD50 frequently had a monoexponential function and time constants were 1.8 +/- 0.1 s. Restitution curves of APD90 were biphasic: a descending phase followed by an ascending phase. The blocker of Ito1 (a 4-aminopyridine-sensitive component of the transient outward current), 4-aminopyridine, flattened the restitution curves of phase I amplitude, and APD50 and APD90 curves became monophasic. Sotalol, a selective IKr (a rapid component of the delayed rectifier K+ current) blocker, did not alter curves of phase I amplitude and APD50 but shifted APD90 curves upward. Cadmium, a Ca2+ blocker shifted curves of phase I amplitude and APD50 downward and abolished the ascending phase of APD90 curves. We conclude that kinetics of Ito1 and ICa (calcium current) may account for characteristics of restitution of atrial repolarization in rabbit.
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Affiliation(s)
- A Qi
- Department of Medicine, University of British Columbia, Vancouver, Canada
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Roberts EH, Qi A, Ellis RH, Summerfield RJ, Lawn RJ, Shanmugasundaram S. Use of field observations to characterise genotypic flowering responses to photoperiod and temperature: a soyabean exemplar. Theor Appl Genet 1996; 93:519-533. [PMID: 24162343 DOI: 10.1007/bf00417943] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/1995] [Accepted: 01/19/1996] [Indexed: 06/02/2023]
Abstract
Thirty-nine accessions of soyabean [Glycine max (L.) Merrill] and 1 of wild annual soyabean (Glycine soja L.) were sown at two sites in Taiwan in 1989 and 1990 and on six occasions during 1990 at one site in Queensland, Australia. On two of the occasions in Australia additional treatments extended natural daylengths by 0.5 h and 2 h. The number of days from sowing for the first flower to appear on 50% of the plants in each treatment was recorded (f), and from these values the rate of progress towards flowering (1/f) was related to temperature and photoperiod. In photoperiod-insensitive accessions it was confirmed that the rate is linearly related to temperature at least up to about 29°C. In photoperiod-sensitive genotypes this is also the case in shorter daylengths but when the critical photoperiod (P c) is exceeded flowering is delayed. This delay increases with photoperiod until a ceiling photoperiod (P ce) is reached. Between P c and P ce, 1/f is linearly related to both temperature (positive) and photoperiod (negative), but in photoperiods longer than P ce there is no further response to either factor. The resulting triple-intersecting-plane response surface can be defined by six genetically-determined coefficients, the values of which are environment-independent but predict time to flower in any environment, and thus quantify the genotype x environment interaction. By this means the field data were used to characterise the photothermal responses of all 40 accessions. The outcome of this characterisation in conjunction with an analysis of the world-wide range of photothermal environments in which soyabean crops are grown lead to the following conclusions: (1) photoperiod-insensitivity is essential in soyabean crops in temperate latitudes, but such genotypes flower too rapidly for satisfactory yields in the tropics; (2) photoperiod-sensitivity appears to be essential to delay flowering sufficiently to allow adequate biomass accumulation in the warm climates of the tropics; (3) contrary to a widely held view, some degree of photoperiod-sensitivity is also needed in the tropics if crop-duration homeostasis is required where there is variation in sowing dates (this is achieved through a photoperiod-controlled delay in flowering which counteracts the seasonal increase in temperature that is correlated with increase in day-length); and (4) a greater degree of photoperiod-sensitivity is necessary to provide maturity-date homeostasis for variable sowing dates - a valuable attribute in regions of uncertain rainfall. Since the triple-intersecting-plane response model used here also applies to other species, the use of field data to characterise the photothermal responses of other crops is discussed briefly.
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Affiliation(s)
- E H Roberts
- Plant Environment Laboratory, Department of Agriculture, The University of Reading, Cutbush Lane, RG2 9AD, Shinfield, Reading, UK
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Qi A, Yeung-Lai-Wab JA, Kerr CR. pH-dependent actions of 4-aminopyridine on atrial repolarization: effects on the transient outward current. Can J Physiol Pharmacol 1996. [DOI: 10.1139/y96-024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Qi A, Yeung-Lai-Wah JA, Kerr CR. pH-dependent actions of 4-aminopyridine on atrial repolarization: effects on the transient outward current. Can J Physiol Pharmacol 1996; 74:305-12. [PMID: 8773411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Effects of extracellular pH (pHo) were examined on the changes in atrial repolarization induced by 4-aminopyridine (4AP), which is a selective blocker of the transient outward potassium channel, I(to). Action potential parameters were measured, using the conventional microelectrode technique, in the absence and presence of 4AP (0.1-3.0 mM) at pHo 6.5, 7.25, and 8.0. Phase 1 amplitude served as an index of I(to). The onset and recovery kinetics of phase 1 amplitude were assessed at a basic cycle length of 0.5 s, and time constants (tau on and tau r) were computed. Both onset and recovery kinetics had monoexponential functions. Tonic blockade was influenced by external pH, and Kd for half block was 0.19, 0.44, and 2.43 mM for pHo 8.0, 7.25, and 6.5, respectively. Phasic block was defined and exhibited cycle length dependence. Phasic block was also modified by external pH with the greatest effect at pHo 8.0. 4AP (0.3 mM) accelerated tau on, 0.62 +/- 0.2, 0.55 +/- 0.1, and 2.0 +/- 0.8 beats for pHo 8.0, 7.25, and 6.5 compared with control 6.8 +/- 1.9, 6.3 +/- 1.9, and 5.1 +/- 1.4 beats. In contrast, 4AP slowed tau r by about 1 s from control value to 1.5 +/- 0.5 s at pHo 6.5, 4.8 +/- 1.5 s at pHo 7.25 (p < 0.05), and 5.7 +/- 2.0 s at pHo 8.0. We conclude that an increase in extracellular pH enhances block of Ito induced by 4AP, whereas low pHo attenuates the block.
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Affiliation(s)
- A Qi
- Department of Medicine, University of British Columbia, Vancouver, Canada
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Upadhyay AP, Summerfield RH, Ellis RH, Roberts EH, Qi A. Variation in the durations of the photoperiod-sensitive and photoperiod-insensitive phases of development to flowering among eight maturity isolines of soyabean [Glycine max (L.) Merrill]. Ann Bot 1994; 74:97-101. [PMID: 19700467 DOI: 10.1093/aob/74.1.97] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
In soyabean [Glycine max (L.) Merrill] the period between sowing and flowering is comprised of three successive developmental phases--pre-inductive, inductive and post-inductive--in which the rate of development is affected, respectively, by temperature only, by photoperiod and temperature, and then again by temperature only. A reciprocal-transfer experiment (carried out at a mean temperature of 25 degrees C) in which cohorts of plants were transferred successively between short and long photoperiods and vice-versa showed that eight combinations of three pairs of maturity alleles (E(1)/e(1), E(2)/e(2), E(3)/e(3)) had their greatest effect on the duration of the inductive phase in long days. This phase was increased with the increasing photoperiod sensitivity induced by the different gene combinations, and ranged from about 27 to 54 d according to genotype. In a short day regime (11.5 h d(-1)), less than the critical photoperiod, the duration of the inductive phase was brief-requiring about 11 photoperiodic cycles in the less photoperiod-sensitive genotypes and only about seven cycles in the more sensitive ones. The maturity genes also affected the duration of the two photoperiod-insensitive phases; these durations were positively correlated with the photoperiod-sensitivity potential of the gene combinations. The largest effect was on the pre-inductive phase which varied from 3 to 11 d, while the post-inductive phase varied from about 13 to 18 d. As a consequence of these nonphotoperiodic effects of the maturity genes, even in the most inductive regimes (daylengths less than the critical photoperiod) the time taken to flower by the less photoperiod-sensitive combinations of maturity genes was somewhat less than in the more sensitive combinations-ranging from about 28 to 34 d. The genetic and practical implications of these findings are discussed.
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Affiliation(s)
- A P Upadhyay
- Plant Environment Laboratory, Department of Agriculture, University of Reading, Cutbush Lane, Shinfield, Reading RG2 9AD, UK
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Upadhyay AP, Ellis RH, Summerfield RJ, Roberts EH, Qi A. Characterization of photothermal flowering responses in maturity isolines of soyabean [Glycine max (L.) Merrill] cv. Clark. Ann Bot 1994; 74:87-96. [PMID: 19700466 DOI: 10.1093/aob/74.1.87] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
All eight isolines of three maturity genes (E(1)/e(1), E(2)/e(2), and E(3)/e(3)) of soyabean [Glycine max (L.) Merrill] cv. Clark were grown in widely different combinations of photoperiod and temperature. Under the more inductive conditions, i.e. in a warm mean temperature (30 degrees C) when daylengths were less than the critical value (i.e. less than about 13 h), the isolines flowered at similar times (23-24 d). The responses of all isolines to temperature were also similar, if not identical. Increase in daylength above the critical photoperiod progressively delayed flowering until the time taken to flower (f) reached a maximum at the ceiling photoperiod. The relations between the rate of progress towards flowering (1/f) and photoperiod (between the critical and ceiling values) were linear. The coefficient characterizing the slope of the response (photoperiod sensitivity) varied amongst the isolines. These responses could be grouped into three categories of increasing sensitivity: (1) least sensitive, e(1)e(2)e(3), e(1)E(2)e(3), e(1)e(2)E(3); (2) intermediate, E(1)e(2)e(3), e(1)E(2)E(3), and (3) most sensitive, E(1)E(2)e(3), E(1)e(2)E(3), E(1)E(2)E(3). Thus, in the Clark cultivar genetic background, E(1) induces greater photoperiod sensitivity but neither E(2) nor E(3) on their own have any effect. However, both E(2) and E(3) together induce photoperiod sensitivity comparable to that induced by E(1) alone. Furthermore, in addition to this epistasis, either E(2) or E(3) has considerable epistatic effect on E(1), further increasing photoperiod sensitivity. The effects of these genes and their epistasis were also reflected in the extent of the maximum delays to flowering which occur when the ceiling photoperiod is exceeded, and also possibly in earliness in circumstances when photoperiods were below the critical value.
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Affiliation(s)
- A P Upadhyay
- Plant Environment Laboratory, Department of Agriculture, University of Reading Cutbush Lane, Shinfield, Reading RG2 9AD, UK
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Qi A, Kerr CR, Yeung-Lai-Wah JA. Electrophysiologic properties of a narrow isthmus in rabbit atrial tissue: cycle length dependent effect of quinidine. Can J Physiol Pharmacol 1994; 72:375-81. [PMID: 7922869 DOI: 10.1139/y94-055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The modulation of quinidine's effect by pacing cycle lengths was assessed over an isthmus of atrial myocardium, simulating the Wolff-Parkinson-White syndrome. Isolated rabbit atria were dissected so that two tissue blocks, A and B, were linked by an isthmus, 1 mm in width. Effective refractory period in the tissue blocks and over the isthmus was measured at cycle lengths of 1,000, 600, and 400 ms, and the minimum cycle length to sustain 1:1 conduction over the isthmus was measured before treatment, during quinidine superfusion (4 mg/L), and after washout. Longitudinal velocity over the isthmus was also measured. The increment in the effective refractory period in the tissue blocks by quinidine appeared to be similar, about 10% at three pacing cycle lengths (p > 0.05). However, the increment of the effective refractory period over the isthmus was modulated by pacing cycle lengths: greater increase at shorter cycle lengths (p < 0.001). Quinidine prolonged the minimum cycle length over the isthmus by 44 +/- 17%. Regression analysis showed that after quinidine there was a correlationship between conduction velocity and refractoriness over the isthmus (R = 0.85, p < 0.001). Intracellular implements showed stable action potentials, confirming the integrity of the preparation. We conclude that (i) quinidine preferentially prolongs refractoriness over the isthmus and (ii) quinidine's effect on refractoriness over the isthmus is cycle length dependent.
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Affiliation(s)
- A Qi
- Department of Medicine, Cardiology, University Hospital, UBC Site, University of British Columbia, Vancouver, Canada
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Abstract
Regional differences in rabbit atrial repolarization were investigated using a conventional microelectrode technique. A more rapid phase 1 repolarization (lower phase 1 amplitude) was seen in the left atrial (LA) roof area compared with the right atrial (RA) roof area: 54 +/- 10 vs. 82 +/- 6 mV at 1,000 ms (P < 0.001). In addition, action potential duration at 40 mV above the resting potential (APD40) was shorter in LA and was associated with a slower phase 3 repolarization rate. Furthermore, the recovery time constant of phase 1 amplitude at 500 ms was 0.9 +/- 0.2 s in LA and 3.5 +/- 1.5 s in RA (P < 0.001). Pacing cycle lengths (2,000, 1,500, 1,000, 800, and 500 ms) modulated phase 1 amplitude, APD40, and phase 3 rate in both regions. 4-Aminopyridine (4-AP; 1 mM), a selective transient outward current (I(to)) blocker, abolished cycle length dependence of the above action potential parameters and diminished the differences in electrophysiological properties between the two regions. 4-AP also flattened the restitution curve of phase 1 amplitude in both regions. In conclusion, the findings suggest that the different kinetics of I(to) play an important role in regional differences of atrial repolarization.
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Affiliation(s)
- A Qi
- Department of Medicine, University of British Columbia, Vancouver, Canada
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Affiliation(s)
- C J Murdock
- University Hospital (UBC Site), University of British Columbia, Vancouver, Canada
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Abstract
Characteristics of left bundle branch block morphology, inferiorly directed frontal plane QRS axis and repetitive nonsustained salvos were used to define a discrete subgroup of patients with ventricular tachycardia (VT). The origin of this tachycardia was thought to be the right ventricular outflow tract. Twenty-six patients with this definition (group 1) were compared with 29 consecutive patients with all other forms of VT (group 2). When compared with patients in group 2, group 1 patients were younger (average age 37 vs 51 years, p less than 0.005), had less structural heart disease (2 of 26 vs 25 of 29 patients, p less than 0.005) and had a better prognosis (no deaths) after an average follow-up time of 28 months in comparison with 5 deaths after an average follow-up of 35 months (p less than 0.05). Induction of VT was possible using isoproterenol infusion in 14 of 20 group 1 patients, but no VT could be induced in 9 group 2 patients (p less than 0.05). Exercise stress testing induced VT in 11 of 21 group 1 patients and 2 of 9 group 2 patients (p greater than 0.05). Programmed electrical stimulation failed to induce VT in 9 group 1 patients, but did induce it in 15 of 20 group 2 patients (p less than 0.005). Successful therapy in group 1 patients was achieved by beta blockers alone (7 patients), beta blockers plus type 1A antiarrhythmic drugs (9 patients), procainamide alone (2 patients), sotalol (3 patients) and amiodarone (2 patients). Three patients were not treated.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- A H Ritchie
- Division of Cardiology, University Hospital, University of British Columbia, Vancouver, Canada
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