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Biomedical subjects

R J Ellis

Publications and source records attributed to R J Ellis.

At least 145 records · Page 8Linked to original sources
PubMed1979

Protection of myocardial function not enhanced by high concentrations of potassium during cardioplegic arrest.

Myocardial performance was evaluated intraoperatively in 20 patients undergoing myocardial revascularization when hypothermic potassium cardioplegic arrest was used. High concentrations of potassium (20 mEq/L) were compared to normal concentrations of potassium (5 mEq/L) in hypothermic cardioplegic solutions. The cardioplegic arrest period averaged 53 +/- 3 minutes in the high potassium group and 54 +/- 4 minutes in the low potassium group, Intraoperative calculation of ejection fraction and end-diastolic volume was accomplished by the technique of radiocardiography. All data were grouped according to end-diastolic volume index (EDVI) for both high (HK) and low (LK) potassium comparisons. Comparisons between high and low potassium groups demonstrated no significant differences in ejection fraction (HK = 66%, LK = 61%), cardiac index (HK = 2.74 L/min/m2, LK = 3.0 L/min/m2), stroke work (HK = 36 gm.m/m2, LK = 30 gm.m/m2), oxygen consumption as measured by left heart double product (HK = 9,438; LK = 9,209), and myocardial compliance (HK = 2.8 cc/torr, LK = 4.2 cc/torr at the post-cardioplegic arrest period). The role potassium plays in producing a rapid cardiac arrest is well accepted. Its protective effect on the preservation of high-energy phosphate stores is postulated, but its addition to perfusion hypothermia does not appear to enhance the protective effect observed with perfusion hypothermia alone.

Cardiac Surgical Procedures↗
PubMed1978

Potassium cardioplegia: early assessment by radionuclide ventriculography.

Left ventricular function was evaluated by single pass Tc-99m radionuclide ventriculography when potassium cardioplegia was combined with hypothermia. In 35 patients undergoing myocardial revascularization (3 CABG/patient) in which potassium cardioplegia at 4 degrees C was used, no patient developed a myocardial infarction either by electrocardiogram or Tc-99m pyrophosphate imaging in the postoperative period. In 22 patients, aortic cross-clamp time was greater than 60 min, and the ejection fraction by the single pass radionuclide technique was 50% preoperatively and 53% postoperatively (NS). Wall motion in the single RAO view was not worse postoperatively. No patient required any inotropic agents in the immediate postoperative period. It appears that no significant ventricular impairment occurred in the immediate postoperative period (48 to 72 hours) when potassium cardioplegia combined with hypothermia was used for a 60-minute period.

Adult↗
PubMed1977

Advantages of potassium cardioplegia and perfusion hypothermia in left ventricular hypertrophy.

An attempt was made to determine the effect of hypothermic potassium cardioplegia (35 mEq of potassium chloride) on the hypertrophic ventricle. Puppies with induced left ventricular hypertrophy were divided into four groups and studied after one hour on global ischemia. Myocardial adenosine triphosphate (ATP) was best preserved in the hypothermically perfused groups and correlated well with measurements of coronary sinus creatine phosphokinase (CPK). In Groups 1 and 2 (anoxic arrest at 37 degrees C and KC1 perfusion at 37 degrees C), CPK at 30 minutes of reperfusion was 1,031 and 198 IU, respectively, compared to 35 IU in Group 3 (KC1 perfusion at 4 degrees C) and 44 IU in Group 4 (Ringer's lactate at 4 degrees C). Myocardial injury was milder in Groups 3 and 4 regardless of whether potassium chloride was added. It is apparent that hypothermic perfusion of a hypertrophic ventricle was the major factor in myocardial preservation, as determined by myocardial ATP and coronary sinus CPK.

Adenosine Triphosphate↗
PubMed1976

Protein synthesis in chloroplasts. VII. Initiation of protein synthesis in isolated intact pea chloroplasts.

Isolated intact pea chloroplasts use light energy to synthesise N-formayl [35S]-methionylpuromycin when incubated with L-[35S]methionine and puromycin. Control experiments establish that this synthesis occurs on chloroplast ribosomes, and not on contaminating mitochondrial or bacterial ribosomes. The amount of N-formylmethionylpuromycin formed suggests that each messenger RNA that is being translated in vitro undergoes initiation at least twice. We conclude that isolated, intact pea chloroplasts carry out the initiation of protein synthesis, as well as the elongation and termination of polypeptide chains.

Binding Sites↗
PubMed1975

Protein synthesis in chloroplasts. IV. Polypeptides of the chloroplast envelope.

Envelope membranes were isolated from washed chloroplasts of pea seedlings. As judged by the protein-to-chlorophyll ratio, average preparations contain less than 8 percent contamination with internal lamellar membranes. Electrophoresis on sodium dodecylsulphate polyacrylamide gels shows that the envelope membranes contain at least 25 polypeptides. The molecular weight distribution of the envelope polypeptides is different from that of the lamellar polypeptides, there being more polypeptides of molecular weights above 50 000 in the envelopes. Two envelope polypeptides become labelled when isolated intact chloroplasts are incubated in the light with (35S) methionine. One of these is similar in molecular weight to the main polypeptide labelled in lamellae, but the other is unique to the envelope fraction. Incorporation of label into both polypeptides is totally light-dependent and is inhibited by chloramphenicol. When (35S) methionine is fed to detached pea shoots with and without cycloheximide, the labelling of other envelope polypeptides is inhibited. We conclude that two polypeptides of the chloroplast envelop are synthesised by chloroplast ribosomes.

Cell Membrane↗
PubMed1975

Immunologic competence of regional lymph nodes in patients with breast cancer.

In 24 patients undergoing radical mastectomy, the degree of sensitization to breast cancer was compared between lymphocytes obtained from regional lymph nodes and circulating lymphocytes. Using the direct lymphocyte migration inhibition assay a greater immunologic response was observed in regional lymph node lymphocytes as compared to circulating lymphocytes when challenged with breast cancer antigen in vitro. In the breast cancer group, migration inhibition (M.I.) was 21% plus or minus 3% in the regional lymph node (R.L.N.) lymphocytes, as compared to 7% plus or minus 3% in the peripheral blood (P.B.) lymphocytes (p smaller than .01). In the control group M.I. was - 10% plus or minus 2% in the R.L.N. lymphocytes, as compared to - 2% plus or minus 3% in the P.B. lymphocytes (p equal to n.s.) indicating no immunologic response to the breast cancer antigen. A significant delayed hypersensitivity response (M.I.greater 20%) was found in 17/24 regional lymph nodes of the radical mastectomy graoup, as compared to 7/24 in the peripheral blood samples tested in the same group, indicating a superior immune response in the regional lymph node lymphocyte population. These data support the concept that regional lymph nodes in breast cancer patients are immunologically competent, and that the lymphocytes in these nodes are more reactive with a tumor antigen than are the circulating lymphocytes.

Antigens, Neoplasm↗
PubMed1975

Protein synthesis in chloroplasts. Characteristics and products of protein synthesis in vitro in etioplasts and developing chloroplasts from pea leaves.

The function of plastid ribosomes in pea (Pisum sativum L.) was investigated by characterizing the products of protein synthesis in vitro in plastids isolated at different stages during the transition from etioplast to chloroplast. Etioplasts and plastids isolated after 24, 48 and 96h of greening in continuous white light, use added ATP to incorporate labelled amino acids into protein. Plastids isolated from greening leaves can also use light as the source of energy for protein synthesis. The labelled polypeptides synthesized in isolated plastids were analysed by electrophoresis in sodium dodecyl sulphate-ureapolyacrylamide gels. Six polypeptides are synthesized in etioplasts with ATP as energy source. Only one of these polypeptides is present in a 150 000g supernatant fraction. This polypeptide has been identified as the large subunit of Fraction I protein (3-phospho-D-glycerate carboxylyase EC 4.1.1.39) by comparing the tryptic 'map' of its L-(35S)methionine-labelled peptides with the tryptic 'map' of large subunit peptides from Fraction I labelled with L-(35S)methionine in vivo. The same gel pattern of six polypeptides is seen when plastids isolated from greening leaves are incubated with either added ATP or light as the energy source. However, the rates of synthesis of particular polypeptides are different in plastids isolated at different stages of the etioplast to chloroplast transition. The results support the idea that plastid ribosomes synthesize only a small number of proteins, and that the number and molecular weight of these proteins does not alter during the formation of chloroplasts from etioplasts.

Adenosine Triphosphate↗
PubMed1975

Distal coronary artery bypass: local occlusion vs. ischemic arrest.

A retrospective study was performed on 65 patients with intractable angina and subtotal coronary occlusions undergoing aortocoronary artery bypass (ACB) to determine whether the local occlusion (L.O.) or the ischemic arrest (I.A.) technique was perferable in performing the distal coronary artery bypass. In 23 patients who had the method of local occlusion, a 45.7 percent incidence of myocardial injury was observed, compared to 42 patients undergoing ACB with ischemic arrest in whom an incidence of 22.5 percent occurred. Both serum glutamic oxaloacetic transaminase (SGOT) and creatine phosphokinase activity (CPK) determinations at 24 hours following operation in those patients not demonstrating evidence of postoperative injury were statistically higher in the local occlusion group compared to the ischemic arrest group. In the L.O. group SGOT was 155 I.U. compared to 77 I.U. in the I.A. group (p less than 0.01). CPK was 72 I.U. in the L.O. groupcompared to 34 I.U. in the I.A. group (p less than 0.05). These data suggest that, in subtotal coronary artery obstruction, the use of the L.O. technique is associated with a higher incidence of myocardial injury than is the technique of total cardiac I.A.

Angina Pectoris↗