Mapping of the oat crown rust resistance gene Pc91.

Crown rust is an important disease of oat caused by Puccinia coronata Corda f. sp. avenae Eriks. Crown rust is efficiently and effectively managed through the development of resistant oat varieties. Pc91 is a seedling crown rust resistance gene that is highly effective against the current P. coronata population in North America. The primary objective of this study was to develop DNA markers linked to Pc91 for purposes of marker-assisted selection in oat breeding programs. The Pc91 locus was mapped using a population of F7-derived recombinant inbred lines developed from the cross 'CDC Sol-Fi'/'HiFi' made at the Crop Development Centre, University of Saskatchewan. The population was evaluated for reaction to P. coronata in field nurseries in 2008 and 2009. Pc91 mapped to a linkage group consisting of 44 Diversity Array Technology (DArT) markers. DArTs were successfully converted to sequence characterized amplified region (SCAR) markers. Five robust SCARs were developed from three non-redundant DArTs that co-segregated with Pc91. SCAR markers were developed for different assay systems, such that SCARs are available for agarose gel electrophoresis, capillary electrophoresis, and Taqman single nucleotide polymorphism detection. The SCAR markers accurately postulated the Pc91 status of 23 North American oat breeding lines.

Electrophysiology of rabbit Müller (glial) cells in experimental retinal detachment and PVR.

PURPOSE: To determine the electrophysiological properties of Müller (glial) cells from experimentally detached rabbit retinas. METHODS: A stable local retinal detachment was induced by subretinal injection of a sodium hyaluronate solution. Müller cells were acutely dissociated and studied by the whole-cell voltage-clamp technique. RESULTS: The cell membranes of Müller cells from normal retinas were dominated by a large inwardly rectifying potassium ion (K+) conductance that caused a low-input resistance (<100 M(Omega)) and a high resting membrane potential (-82 +/- 6 mV). During the first week after detachment, the Müller cells became reactive as shown by glial fibrillary acidic protein (GFAP) immunoreactivity, and their inward currents were markedly reduced, accompanied by an increased input resistance (>200 M(Omega)). After 3 weeks of detachment, the input resistance increased further (>300 M(Omega)), and some cells displayed significantly depolarized membrane potentials (mean -69 +/- 18 mV). When PVR developed (in 20% of the cases) the inward K+ currents were virtually completely eliminated. The input resistance increased dramatically (>1000 MOmega), and almost all cells displayed strongly depolarized membrane potentials (-44 +/- 16 mV). CONCLUSIONS: Reactive Müller cells are characterized by a severe reduction of their K+ inward conductance, accompanied by depolarized membrane potentials. These changes must impair physiological glial functions, such as neurotransmitter recycling and K+ ion clearance. Furthermore, the open probability of certain types of voltage-dependent ion channels (e.g., Ca2+-dependent K+ maxi channels) increases that may be a precondition for Müller cell proliferation, particularly in PVR when a dramatic downregulation of both inward current density and resting membrane potential occurs.

Variability of the random amplified polymorphic DNA assay among thermal cyclers, and effects of primer and DNA concentration.

The reproducibility of the generation of random amplified polymorphic DNA fragments from three commonly used thermal cyclers was determined using identical assay conditions. In all cases, different results were obtained from the three instruments. Variation in the length of the primer (20 nt or 10 nt) did not have any effect on the reproducibility of the assays from the three machines tested. A DNA concentration of 1 ng generated poorly staining DNA fragments whereas concentrations between 10 ng and 100 ng gave similar banding patterns when using the same thermal cycler. Low concentrations of primer (0.05 microM) did not produce any detectable DNA fragments. Increased primer concentrations of 0.25 microM or higher generated intensely staining DNA fragments, and concentrations above 0.5 microM did not improve the clarity of the banding patterns but did direct the synthesis of increasing amounts of very short DNA fragments. Surprisingly, the 20 nt-long primer was able to direct the synthesis of more DNA fragments than a primer of only 10 nt long.

Left ventricular aneurysm and intraventricular thrombi. Investigation and surgical correlations.

Formation of a left ventricular aneurysm and intraventricular thrombus represents one of the dreaded sequelae of coronary artery disease and acute myocardial infarction. The present emphasis is to reduce the incidence by reduction of cholesterol and fats, elimination of smoking, improved detection and control of hypertension and diabetes mellitus. Earlier diagnosis is available with stress testing and other noninvasive techniques. Cardiac catheterization allows detection of occlusive lesions. The CASS and other studies increasingly prove that percutaneous angioplasty and coronary artery bypass surgery improve life expectancy and implicitly should reduce the incidence of acute myocardial infarction. In the setting of the latter, thrombolytic agents may reduce the amount of myocardial injury. Despite these measures, formation of left ventricular aneurysms remains a common occurrence. Diagnosis and management are critical issues to the cardiac surgeon.

Results of emergent versus elective cardiac transplantation procedures.

Twenty-six patients underwent emergent (Group I) and 34 patients elective (Group II) cardiac transplantation (C. Tx.) from June 1985 through June 1989. Age, sex, etiology, presence of diabetes, renal failure and pulmonary artery pressures were comparable for both groups (P greater than 0.5). Twenty-two patients were in New York Heart Association (NYHA) Class IV for Group I and 17 for Group II. Group I included 12 patients on inotropic agents, five on intra-aortic balloon pump (IABP) and one on IABP and cardiopulmonary bypass (CPB). Elective patients were stable at home. Location of the donor heart and mean ischemic times were comparable for both groups. Early mortality (within 30 days) included four patients for Group I and two for Group II. There were four late deaths for Group I patients and six for Group II. Four deaths were due to infection, six to rejection, two to malignancy, two neurological and one each to suicide and multisystem failure. Immunosuppression regimen was similar for both groups. The number and severity of early and late rejection episodes were similar despite blood group crossing in 11 patients for Group I (P less than .01). Incidence of infection was comparable. Favorable lifestyles were comparable, including employment of 12 patients for Group I and 16 for Group II. Cumulative survival for the entire series was 70% at two years. The study indicates that the results of emergent and elective cardiac transplantation procedures are equally gratifying, that mortality is mainly related to rejection and sepsis complications and blood group crossing does not significantly increase the number of rejection episodes.

Safety and efficacy of internal mammary artery grafts for left main coronary artery disease. A preliminary report.

Questions regarding the relative safety and efficacy of internal mammary artery (IMA) grafts versus saphenous vein grafts (SVG) in patients with left main coronary artery disease (LMCAD) have not been specifically addressed in the literature. To elucidate this point, we analyzed 196 patients with LMCAD who underwent myocardial revascularization between January 1975 and December 1981, 98 by IMA and SVG and 98 by SVG, IMA was used most often to bypass the left anterior descending (LAD). Chi Square and "t" tests were performed on all demographic, cardiac and operative data comparing IMA to SVG. All results were non-significant, indicating that the two groups were comparable. Anginal pattern was progressive or unstable in 93%. IMA was used in 4 patients who were on intra-aortic balloon pump. The mean number bypass grafts per patient was 3.1. Postoperative complications were comparable for both groups, including early and late myocardial infarction. Overall operative mortality was 2.6%. Results of a survival analysis indicated no significant difference in the mortality rates of patients operated on by SVG versus IMA-SVG. Cumulative mortality rates at a mean followup of 20.5 months were 12.2% for SVG and 7.1% for IMA patients. Significant mortality risk factors were ejection fraction less than 55% (p less than 0.05); and perioperative myocardial infarction (p less than 0.001). Twenty-five patients with recurrent chest pain underwent repeat cardiac catheterization. This revealed 10 of 10 patent IMA grafts, 6 of 8 single patent SVG to LAD and 6 of 9 patent sequential vein grafts to the diagonal and LAD arteries.(ABSTRACT TRUNCATED AT 250 WORDS)

Results of coronary bypass surgery in elderly women.

One hundred two female and 102 male patients all older than 70 years who underwent coronary artery bypass grafting (CABG) between 1978 and 1983 were matched according to age, anginal status, ejection fraction (EF), number of bypass grafts, and year of operation. These 204 patients were characterized by a mean age of 73 years, a mean EF of 64%, a mean of 3.2 bypass grafts per patient, and unstable angina in 82%. Statistical analyses were performed on the following variables in conjunction with patient sex to determine whether the two samples (women and men) can be considered representative of a single patient population: preoperative resting ECG, stress test result, number of diseased vessels, left ventricular end-diastolic pressure, presence of carotid artery disease, use of an internal mammary artery graft, incidence of operative death, perioperative myocardial infarction (MI), hospital complications, late MI, recurrent angina, late death, and cumulative survival. All differences were small and failed to reach statistical significance except that women had a higher incidence of recurrent angina-like chest pain and a higher incidence of ischemic changes in the preoperative ECG and men had a higher incidence of conduction abnormalities. We conclude that in this age group, CABG is equally beneficial to women and men in terms of survival, but may result in less subjective symptomatic benefit in women.

Advantages of superior approach for mitral valve surgery.

Technical factors in mitral valve surgery (MVS) which may influence neurological complications, trauma to the left atrium and formation of atrial mural thrombi have not previously been described in detail. We have reviewed the records of 146 patients (pts) undergoing MVS through the superior approach between January 1974 and May 1981. The series consisted of 97 females and 49 males with a mean age of 57 +/- 18 years. All but 4 pts were in New York Heart Association functional class III or IV. Twenty-five pts underwent open mitral commissurotomy, 116 had valve replacement and 5 had annuloplasty. Concomitant procedures were coronary bypass in 47, aortic valve replacement in 18 and resection of left ventricular aneurysm in 3. Left atrial thrombi were removed in 21 pts. Thirteen pts (9%) died postoperatively. The causes of death were left ventricular failure in 7, arrhythmia in 4 and atrio-ventricular disruption in 2. Two of these pts also had cerebral dysfunction. Autopsy examination in 8 pts failed to reveal formation of fresh left atrial septal or posterior mural thrombus. Postoperative complications included transient neurologic injury presumed to be due to air embolus in 3 and postoperative bleeding from atrial suture line in one. The mean follow-up for the survivors has been 30 months. There have been 16 (12%) late deaths from 1 to 72 months (mean 15). Autopsy examination of 4 pts and surgical exploration in one other pt which failed to reveal organized left atrial mural thrombus. Only one late death was related to prosthetic thrombosis. This occurred following cessation of anticoagulations.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary bypass for left main disease in patients over 70 years of age.

Seventy-one consecutive patients over 70 years of age underwent isolated coronary bypass surgery for left main coronary artery (LMCA) disease between September 1975 and December 1982. All patients had angina; 6% were in NYHA functional class II, 30% class III, and 64% class IV. Intravenous nitroglycerin was required in 25% of patients. Resting electrocardiogram was abnormal in 91% of patients and stress testing performed in 24 patients was positive in all. Degree of left main stenosis graded by diameter was 60 to 70% in 24% of patients and greater than 70% in 76%. In addition to left main stenosis 66% of patients had significant triple vessel disease. Left ventricular end diastolic pressure (LVEDP) was elevated in 69% of patients while ejection fraction (EF) was low only 24%, without correlation between high LVEDP and low EF. Mean number of bypass grafts per patient was 3.4 +/- 0.6. Hospital mortality was 7% and mean post-operative stay was 10.4 +/- 2.0 days. Stepwise multiple regression analysis of 12 variables identified only unstable angina requiring intravenous nitroglycerin as a significant predictor of hospital mortality (p less than 0.01). Follow-up was complete with a late cardiac mortality of 4.5%. Seventy-five percent of surviving patients assessed their quality of life as good at a mean follow-up of 26 months. Coronary bypass for LMCA disease in a non-selected elderly population can be performed with low operative mortality and marked improvement in quality of life.

Fluctuations of the atrial cycle length and A-V delay with a universal (DDD) pacemaker.

The electronic characteristics of a new universal (DDD) pulse generator can result in significant shortening of the atrial cycle length (A-A interval) and shortening of the atrioventricular (A-V) interval beyond the programmed values. These pacemaker arrhythmias are entirely compatible with normal function and must not be interpreted as malfunctions.

Surgical treatment of 200 consecutive patients with left main coronary artery disease.

Two hundred consecutive patients underwent myocardial revascularization for left main coronary artery disease between January, 1975, and December, 1981. The mean age of this group was 64 +/- 8 years, and 78.5% of the patients were men. The anginal pattern was chronic stable in 6% of the patients and progressive or unstable in the remainder. Resting electrocardiograms showed prior myocardial infarction in 45.5%. Left ventricular end-diastolic pressure was elevated in 145 patients, and ejection fraction was less than 50% in 40 patients. The mean number of bypass grafts per patient was 3.2 +/- 1.4 (standard deviation). Seventeen patients underwent major concomitant cardiovascular procedures. The operative mortality was 3.5%, and the incidence of perioperative infarction was 3%. Factors associated with reduced operative survival were increased age; unstable angina, or acute myocardial infarction, or both; female sex; circumflex-dominant circulation; and major concomitant procedures. Late mortality at a mean follow-up of 33.5 months was 6%, and 91% of the surviving patients assessed their quality of life as "excellent" or "good."

Surgical treatment of mitral valve disease: pathologic findings and atrial dysrhythmia.

One hundred fifty patients underwent surgery for mitral valve disease between January 1974 and May 1981. There were 98 female and 52 male patients with a mean age of 57 years (+/- 18.6). One hundred forty-six patients were in New York Heart Association functional class III or IV. Pathologic diagnoses included 67% rheumatic (55 calcified), 27% degenerative and fibrotic, 3.3% prosthetic valve malfunctions, and 2.6% acute papillary muscle dysfunction. Atrial biopsy material was normal in 72% (37/51) and Aschoff's bodies were present in 2% (1/51). Preoperative cardiac rhythm was regular sinus in 40%, atrial fibrillation in 59%, and pacemaker-induced in 1%. Valve replacement was performed in 119 patients, commissurotomy in 26, and annuloplasty in five. Left atrial thrombus was removed from 21 patients. Hospital mortality was 10%. The 135 survivors have been followed up for an average of 30.4 months. Of patients who were in regular sinus rhythm preoperatively, 90.7% maintained it postoperatively, and 9.3% converted to atrial fibrillation. Of patients in atrial fibrillation preoperatively, 33.8% converted to regular sinus rhythm postoperatively and 66.2% remained in atrial fibrillation. These data indicate that rheumatic mitral valve disease is still the most common finding in patients coming to surgery, followed by degenerative and fibrotic mitral valve disease. Acute papillary muscle dysfunction is uncommon. The chance of preserving preoperative regular sinus rhythm postoperatively is excellent (90.7%), and a 33% conversion rate of preoperative atrial fibrillation to postoperative regular sinus rhythm is encouraging.

Peripheral plasma progesterone and oestradiol concentrations associated with successful and unsuccessful recovery of uterine embryos in rhesus monkeys with and without intra-uterine devices.

Concentrations of progesterone and oestradiol were measured in peripheral plasma samples collected at the time when the uteri of rhesus monkeys with an intra-uterine device (IUD) and those without an IUD were flushed in attempts to recover uterine embryos. The proportion of successful attempts in IUD-bearing monkeys was much lower than in the non-IUD-bearing animals. Steroid measurements indicated that this reduced success rate was not due to an effect of the IUD on the timing of ovulation within the menstrual cycle or to a steroid-mediated disturbance in the rate of embryo transport to the uterine lumen. Successful embryo recoveries were associated with a higher progesterone concentration, suggesting that one reason for failure was that the attempt had been made too close to ovulation. There was no evidence of any asymmetry between the left or right ovaries in their ovulatory or steroidogenic activity.

Uterine histology and prostaglandin concentrations and utero-ovarian venous steroid and prostaglandin concentrations during the luteal phase of the menstrual cycle in baboons (Papio spp.) with or without an IUD.

Arachis oil was infused via the oviducts into the uterus of baboons 6-9 days after ovulation; uterine tissue was collected towards the end of the luteal phase (3-7 days after the oil infusion) for histological assessment of the occurrence of any deciduomal reaction. To exclude the possibility that a variation in the endogenous steroid concentrations was responsible for any observed variation in the incidence of the deciduomal reaction, blood samples were collected and assayed for progesterone and oestradiol-17 beta. The effect of the IUD on endometrial prostaglandin release was examined by measuring PGE and PGF concentrations in uterine tissue and utero-ovarian venous plasma. The IUD stimulated a deciduomal response in every animal, whereas the traumatization with arachis oil had no such effect; the variation in the peripheral and utero-ovarian steroid levels could not explain the variation in the incidence of the deciduomal reaction. Greater concentrations of PGF but not PGE were present in the endometria of those animals bearing an IUD and in which a deciduomal reaction had been stimulated. The corpus luteum was the major source of progesterone and of oestradiol-17 beta, although non-luteal ovarian tissue also secreted oestradiol-17 beta.