PubMed Health⌕ Search

Biomedical subjects

A S Palmer

Publications and source records attributed to A S Palmer.

At least 19 recordsLinked to original sources
PubMed2001

Suppressed ion chromatography methods for the routine determination of ultra low level anions and cations in ice cores.

The concentration of trace ionic species in snow and ice samples was determined using suppressed ion chromatography (IC) with conductivity detection and ultra-clean sample preparation techniques. Trace anion species were determined in a single 24-min run by combining sample preconcentration with gradient elution using Na2B4O7 eluent. The detection limits (ranging from 0.001 to 0.006 microM) are the lowest reported in the literature. Cation species were analysed by direct injection of 0.25 ml and isocratic elution with a H2SO4 eluent. The clean preparation techniques showed no evidence of a difference (Student's t-test) between Milli-Q water samples analysed directly and processed Milli-Q ice samples. These robust, ultra-clean IC methods were routinely applied to the analysis of large number of samples to produce a high-resolution trace ion ice core record from Law Dome, East Antarctica.

Anions↗
PubMed2001

Lymphatic drainage of the heart in the laboratory rat.

We showed in the Sprague Dawley rat that the principal ascending cardiac lymphatic is similar in location to that of man and dog and can be readily visualized by injection of a small amount of T1824 blue dye (Evans) into the apex of the left ventricle. We also showed that it is possible to ligate and thereby obstruct this principal cardiac lymphatic near its entry beneath the left atrial appendage. This latter technique may be useful for studying in a small relatively inexpensive laboratory animal the effects of blocking cardiac lymph drainage on inflammatory and infectious processes implicated in myocardial and coronary artery disease.

Animals↗
PubMed2000

Postoperative troponin I values: insult or injury?

BACKGROUND: Troponin I (TnI) is increasingly employed as a highly specific marker of acute myocardial ischemia. The value of this marker after cardiac surgery is unclear. HYPOTHESIS: The purpose of this study was to measure serum TnI levels prospectively at 1, 6, and 72 h after elective cardiac operations. In addition, TnI levels were measured from the shed mediastinal blood at 1 and 6 h postoperatively. Serum values were correlated with cross clamp time, type of operation, incidence of perioperative myocardial infarction, as assessed by postoperative electrocardiograms (ECG) and regional wall motion, as documented by intraoperative transesophageal echocardiography (TEE). METHODS: Sixty patients underwent the following types of surgery: coronary artery bypass graft (CABG) (n = 45), valve repair/replacement (n = 10), and combination valve and coronary surgery (n = 5). Myocardial protection consisted of moderate systemic hypothermia (30-32 degrees C), cold blood cardioplegia, and topical cooling for all patients. RESULTS: Of 60 patients, 57 (95%) had elevated TnI levels, consistent with myocardial injury, 1 h postoperatively. This incidence increased to 98% (59/60) at 6 h postoperatively. There was a positive correlation between the length of cross clamp time and initial postoperative serum TnI (r = 0.70). There was no difference in the serum TnI values whether or not surgery was for ischemic heart disease (CABG or CABG + valve versus valve). There were no postoperative myocardial infarctions as assessed by serial ECGs. There was no evidence of diminished regional wall motion by TEE. Levels of TnI in the mediastinal shed blood were greater than assay in 58% (35/60) of the patients at 1 h and in 88% (53/60) at 6 h postoperatively. Patients who received an autotransfusion of mediastinal shed blood (n = 22) had on average a 10-fold postoperative increase in serum TnI levels between 1 and 6 h. Patients who did not receive autotransfusion average less than doubled their TnI levels over the same interval. At 72 h, TnI levels were below the initial postoperative levels but still indicative of myocardial injury. CONCLUSION: Postoperative TnI levels are elevated after all types of cardiac surgery. There is a strong correlation between intraoperative ischemic time and postoperative TnI level. Further elevation of TnI is significantly enhanced by reinfusion of mediastinal shed blood. Despite these postoperative increases in TnI, there was no evidence of myocardial infarction by ECG or TEE. The postoperative TnI value is even less meaningful after autotransfusion of shed mediastinal blood.

Blood Transfusion, Autologous↗
PubMed1999

A 1-day maximal lactate steady-state assessment protocol for trained runners.

PURPOSE: Identification of the maximal lactate steady state (MLSS) involves multiple days of testing. Heart rate (HR), rating of perceived exertion (RPE), breathing frequency (bf), and race pace may be useful in estimating the MLSS, thus allowing for testing to occur in a single day. The purpose of this investigation was to design a single-session protocol for determining MLSS using HR, RPE, bf, and race pace as predictors. METHODS: Twelve endurance athletes (mean +/- SD, VO2max 64.6 +/- 7.8 mL x kg(-1) x min(-1)) performed the MLSS protocol run and two 27-min validation runs on a treadmill. Running velocity at 87% HRmax RPE of 12, bf of 32 breaths x min(-1), and race pace were used as a starting point for testing. Blood was collected every 3 min of each 9-min stage of the protocol run and analyzed for lactate (La) concentration. The velocity associated with the MLSS was determined as the average of the stage of La steady state and the stage of La accumulation. Validation runs were performed at a velocity 7.5 m x min(-1) below and 7.5 m x min(-1) above the protocol-determined MLSS. If the slower run exhibited a La steady state and the faster run an accumulation of La, then the protocol-determined MLSS value was considered valid. RESULTS: The protocol run was successful in predicting the MLSS in 9 out of 12 subjects (P < or = 0.05). CONCLUSIONS: The proposed protocol employing HR, RPE, bf, and race pace as a starting point for testing can be used to identify the MLSS in one testing session.

Adult↗
PubMed1999

Failure of the canine principal ascending epicardial lymphatic to regenerate after transection.

We transected the principal ascending anterior epicardial cardiac lymphatic in 10 dogs, and after varying time intervals reoperated to look for lymphatic regeneration using dye injection. Photographs and sketches were made to record the findings, and in six dogs serial histologic sections were also examined. In none of the 10 dogs was regeneration of the transected principal cardiac lymphatic detected although small lymphatic collaterals from the distal side of the lymphatic developed in 2 dogs. Further studies are merited to assess the role of lymphatic insufficiency in the development of coronary vasculopathy and chronic rejection after cardiac transplantation and other heart operations (e.g., coronary artery bypass) that may injure lymphatic drainage capacity.

Animals↗
PubMed1998

Gas tensions in cardiac lymph as a reflection of the interstitial space of the heart.

The purpose of this study was to determine the feasibility of measuring partial pressure of oxygen (pO2), partial pressure of carbon dioxide (pCO2), and pH in cardiac lymph and to evaluate the relationship of these parameters to comparable measurements in arterial and coronary sinus blood in the normal heart under various respiratory conditions. In four anesthetized open-chest dogs, the principal cardiac lymphatic as well as the femoral artery and coronary sinus were cannulated. Ventilation was varied by changing oxygen concentration, tidal volume, and respiratory rate. PO2, pCO2, and pH were measured in the cardiac lymph, arterial blood, and coronary sinus blood after each change in ventilation. For pH and pCO2, good correlations were observed between the arterial blood and cardiac lymph, arterial blood and coronary sinus blood, and coronary sinus blood and cardiac lymph. The correlation between the pO2 measured in the arterial blood and the pO2 measured in the cardiac lymph was not as strong, and this may have been related to difficulty achieving a steady state. Gas tensions (pO2, pCO2, and pH) can be measured in cardiac lymph and may provide a window to the interstitial compartment of the heart. This is an additional tool for the laboratory study of ischemia and other forms of heart disease.

Animals↗
PubMed1998

The lymphatic drainage of the left ventricle in the Yucatan minipig.

The gross anatomy of the cardiac lymphatic system draining the left ventricle was studied in 15 Yucatan minipigs and 2 regular swine. The findings confirm that the drainage pathways are similar to those of man and dog. After a coloring marker is injected near the apex of the left ventricle, one or more lymphatics are seen to ascend towards the left atrial appendage. Where there is more than one ascending lymphatic, they typically join before or at the left atrial appendage. This principal lymphatic then passes beneath the appendage and travels behind (dorsal to) the pulmonary artery and aorta to the right side of the mediastinum. From here, the lymphatic passes cephalad along the left border of the superior vena cava to enter the cardiac lymph node between the superior vena cava and the trachea.

Animals↗
PubMed1996

Visualization of the lymphatics of the heart and the mediastinal drainage pathways in the living cynomolgous (Macaca mulatta) monkey.

Our interest in the effects of impaired cardiac lymph drainage on coronary atherosclerosis led us to study the cardiac lymphatic anatomy in the monkey, generally considered the ideal experimental animal for examining coronary artery disorders. Short-term and long-term studies to visualize the cardiac lymphatic system and its mediastinal drainage pathways in 14 living monkeys confirmed that the epicardial collecting lymphatic anatomy is comparable to that of man, dog, and pig. These lymphatics, and particular lymphatic drainage to the cardiac lymph node in the right mediastinum, are difficult to visualize, in good part, because lymph uptake of such tracers as India Ink and T1824 blue dye is extremely slow. By modifying our techniques and taking cognizance of the slow lymphatic uptake of the tracers, we have been more successful in visualizing the mediastinal cardiac lymph node. Though our studies confirm that the lymphatic drainage of the monkey heart is similar to that in other mammals, we conclude that the "monkey model" has several drawbacks to study the effects of impaired cardiac lymph flow because of the laborious requirements to visualize successfully the cardiac lymph node. Perhaps the development of new markers would make this lymphatic system more approachable for experimental investigation.

Animals↗
PubMed1988

Multiple aneurysms in Behçet's disease.

Behçet's disease is characterized by recurrent ulcers of the mouth and genitalia and relapsing iritis. It is now recognized as a chronic multisystem disease affecting the skin, mucous membranes, eye, joints, central nervous system, and blood vessels. One of the known vascular complications of Behçet's disease is aneurysm formation or venous thrombosis. The two patients with Behçet's disease in this report developed multiple aneurysms over a short time span. Vascular surgeons dealing with young adults with peripheral aneurysms must be aware of this uncommon yet challenging clinical entity.

Adult↗
PubMed1988

The lymphatic drainage of the pericardial space in the dog.

The purpose of this study was to characterize definitively the lymphatic drainage system of the pericardial space in the dog. The reports on this subject, based on dissection experiments and acute dye injections, remain controversial, and our own previous studies have been incomplete. Seventeen dogs were studied using a radiographic technique. Micropulverized barium sulfate instilled into the pericardial sac was followed with serial chest x-rays in seven dogs with intact cardiac lymphatics, in seven dogs after section of the cardiac lymphatic drainage node (the cardiac lymph node) in the right upper mediastinum, and in three dogs after resection of cardiac drainage lymphatic nodes in the left upper mediastinum. These studies revealed that the lymphatic drainage of the pericardial space is via (a) the principal coronary lymphatic which drains from the left ventricular muscle and passes to the right upper mediastinum via the cardiac lymph node, (b) the lesser coronary lymphatic which drains the right ventricular muscle and passes to the left upper mediastinum, and (c) bilateral internal mammary (parasternal) lymphatic chains. These observations are important in planning experimental approaches to the effects of impairment of lymph drainage from the pericardial space. An understanding of the lymph drainage from the pericardial space may prove significant to understanding fibrotic reactions within it and the pathologic mechanisms of such entities as constrictive pericarditis.

Animals↗