Cadherin intercellular adhesion molecule in hepatocellular carcinomas: loss of E-cadherin expression in an undifferentiated carcinoma

Expression of E- and P-cadherin in 24 primary hepatocellular carcinomas, together with the non-cancerous liver tissue from each case, was examined by immunohistochemical staining. Cells of 23 grade I-III carcinomas as well as hepatocytes in all the non-cancerous livers expressed E-cadherin at the cell-cell boundary and showed tight intercellular adhesion without exception. However, a highly undifferentiated carcinoma classified as grade IV apparently lacked E-cadherin expression and also showed decreased intercellular adhesiveness. Loss of E-cadherin expression may be one of the characteristics of highly undifferentiated hepatocellular carcinoma. In contrast to E-cadherin, P-cadherin was never detected in either the cancer cells or non-cancerous hepatocytes in all cases.

Expression of E- and P-cadherin in gastric carcinomas

The expression pattern of two Ca2(+)-dependent intercellular adhesion molecules, E- and P-cadherin, in 54 surgically resected gastric adenocarcinomas was examined immunohistochemically. E-cadherin was expressed uniformly at the cell-cell borders of most of the differentiated and adherent-type undifferentiated gastric adenocarcinomas, showing that E-cadherin serves as the main cadherin molecule responsible for intercellular binding in these carcinomas. Scattered-type undifferentiated gastric adenocarcinomas which apparently lacked this tight intercellular adhesion were divisible into two groups on the basis of E-cadherin expression. In a minor group composed of 4 carcinomas, E-cadherin could not be detected, suggesting that the absence of E-cadherin made the cancer cells separate. In contrast, cancer cells of 19 carcinomas which belonged to the major group showed similar scattering but had definite expression of E-cadherin on their cell surfaces, suggesting that there was some mechanism(s) disturbing the function of E-cadherin in these carcinomas. However, immunoblotting showed no evidence of gross alterations of the E-cadherin molecule, such as partial deletion, in these carcinomas. P-cadherin was expressed in 29 (54%) of the examined gastric carcinomas, and the expression was unstable in most of them, a characteristic feature compared with the stable expression of E-cadherin. Since P-cadherin is known to be expressed temporarily in the foregut during embryogenesis and was proved to be occasionally expressed, although weakly, in the proliferative zone of noncancerous gastric epithelia in this study, expression of P-cadherin in gastric carcinomas may be an oncofetal phenomenon and/or may reflect their marked proliferative potential.

[Coronary artery bypass grafting with combined arterial grafts]

Coronary artery bypass grafting with combined arterial graft using the left internal mammary artery (IMA), right IMA, and the right gastroepiploic artery (GEA) was performed in 45 patients with saphenous vein graft (SVG) (29 patients) or without SVG (16 patients) from February 1989 to October 1989. The left IMA was used in all patients, the right IMA was used in 9 patients, and the GEA was used in 43 patients. Perioperative myocardial infarction was noted in two patients who had hospital deaths. Reopening the chest for postoperative bleeding was performed in two patients, and the cerebral accident was noted in one patient. Fourteen patients were operated on without the requirement for blood transfusion. Studied within 3 postoperative months, all arterial grafts were patent though the patency was 97.7% (43/44) in SVG. It is concluded that the combined arterial graft utilizing the IMAs and GEA can be used safely and effectively.

[Valve replacement in infective endocarditis with mycotic aneurysm]

We successfully performed craniotomy and mitral valve replacement on a patient with bacterial endocarditis and ruptured intracranial aneurysm. A 15-year-old woman with fever and heart murmur was admitted to another hospital. Infective endocarditis and mitral valve regurgitation was diagnosed and treated with antibiotics. About one month after admission the patient suddenly showed severe headache and hemiparesis. Brain CT demonstrated intracerebral and subarachnoidal hemorrhage. The patient was unconscious when transferred to Mitsui Memorial Hospital where cerebral angiography showed anterior cerebral aneurysm and echocardiography showed mitral valve vegetation. We judged the necessary mitral valve replacement could be delayed until the aneurysm had been stabilized. We therefore began treatment using a different antibiotic but, in spite of this, 10 days later the aneurysm had enlarged dramatically. As conservative treatment was ineffective, a clipping operation was done to prevent re-rupture at the time of mitral valve replacement which could not be delayed much longer. 10 days later, cerebral 4 vessel study was done which showed no abnormality. Mitral valve replacement was then done and the patient was discharged in good health 64 days after the valve replacement.

Heat production as a quantitative parameter for cell differentiation and cell function

Heat production was measured in relation to cell differentiation and phagocytie function using cells of human monocyte-histiocyte cell line U937. U937 cells differentiated monocytic phagocytes when cultured with lymphokine. Heat production increased as result of differentiation and phagocytosis. An important finding was that the heat increase in differentiated cells and during phagocytosis was directly proportional to the concentration of lymphokine. This strongly suggested that heat production is a quantitative parameter not only for cell differentiation but also for phagocytic function. The measurement of heat produced by mammalian cells can therefore be used to quantitate the differentiation and function of cells.

Aortopulmonary shunt with replacement of a common atrioventricular valve in a patient with double inlet ventricle

Replacement of a common atrioventricular valve with a St. Jude medical prosthesis, together with construction of a central aortopulmonary shunt using a polytetrafluoroethylene graft, were performed on a patient with double inlet ventricle complicated by severe regurgitation across an atrioventricular valve and hypoplastic pulmonary arteries. No complications were noted during a postoperative follow-up of 58 months; indeed, a considerable increase was noted in postoperative exercise capacity. This simple surgical procedure should be considered as a mode of treatment in patients with this combination of lesions.

[A case of bioprosthetic mitral valvular dysfunction due to pannus-formation]

A case of bioprosthetic mitral valvular dysfunction accompanied by mitral stenosis due to pannus is reported. A 69-year-old woman, whose mitral valve had been replaced with a Hancock bioprosthetic valve in June 1979, underwent the second mitral valve replacement in September 1988 because of valvular dysfunction. The ring and cusps of this Hancock valve was partially covered with hard and milky white pannus which resulted in mitral stenosis. The tear of cusp was observed at the point of contact with pannus, which resulted in mitral regurgitation. Histologically, pannus was consisted of two-layered structure, fibrin and collagen fiber, which demonstrated this over-growth was based on thrombus. Main causes of bioprosthetic valve dysfunction are calcification and tear of cusps. But, valvular dysfunction due to pannus-formation described in this case has been experienced very rarely.

[Investigation of primary tissue failure in mitral bioprostheses]

A study was conducted on 118 Hancock (HX) porcine valves, 251 Carpentier-Edwards (CE) porcine valves, and the biological valves in children used in the mitral position. Twenty-three HX valves, twenty-seven CE valves, and all valves except one operative death in children were diagnosed as primary tissue failure (PTF). Freedom from PTF for HX valves was 70.1 +/- 6.0% at ten years and for CE valves was 45.7 +/- 17.0% at ten years, although for children it was calculated 0% at eight years (significantly poor results compared with adults). No relation was found between the degree of calcified cusps and the duration of PTF valves used. The ruptures and calcifications of the cusps were most commonly observed in commissure. The peeled off commissures were characteristic in CE valves. Three adults and two children died without reoperation caused by calcified stenotic valves. Since the risk of reoperation was higher in NYHA functional class four, we recommend earlier elective reoperation.

[Noncardiac surgery in patients with ischemic heart disease]

From January 1983 to December 1988, 4679 patients with operated under general anesthesia in our institute: 161 patients involved suspected ischemic heart disease (IHD patients) by history or electrocardiogram. Eight of 161 patients (5.0%) experienced fatal or life-threatening cardiac complications. On the other hand, only two non-IHD patients (0.03%) experienced complications. IHD patients had a significantly higher incidence of complications compared with non-IHD patients. Forty-five IHD patients had not undergone coronary cineangiogram (CAG) before noncardiac operations and six of them (13.8%) experienced complications. They had a significantly higher incidence of complications compared with other IHD-patients who had received CAG. Fifty-five IHD patients who had already been treated by coronary bypass grafting (CABG) or by percutaneous transluminal angioplasty experienced only one complication. We conclude that CAG should be more actively performed for IHD patients because prior CABG or PTCA is suspected to decrease cardiac complications in IHD patients. However, IHD patients must be managed as carefully as possible.

[A successful repair of post-infarction left ventricular free wall rupture]

Left ventricular free wall rupture secondary to acute myocardial infarction is almost invariably fatal. This report is the case presentation of a successful repair of left ventricular free wall rupture. A 55-year-old man, with a diagnosis of acute infero-lateral myocardial infarction, was transferred from another hospital to our CCU having recurrent chest pain on the fourth day after infarction. Shortly after admission, he lost his consciousness and fell into cardiogenic shock. Echocardiography showed a large pericardial fluid. He was immediately transferred to the operating room with the diagnosis of the heart rupture. After opening the pericardium containing 200 cc of blood, cardiac tamponade was relieved. The posterolateral portion of the left ventricle was found to be bluishly discolored, with a 8 mm-long tear of epicardium. Using cardiopulmonary bypass, the tear was closed with Teflon-reinforced sutures. The post-operative course was uneventful.

[A case of CABG in a patient with chronic idiopathic thrombocytopenic purpura]

This is a report of the management of a patient with chronic idiopathic thrombocytopenic purpura (ITP) and ischemic heart disease. High-dose transvenous gamma-globulin therapy (400 mg/kg/day for five days) was started five days prior to operation, yielding an increase in platelet count from 5.8 X 10(4)/mm3 to 12.8 X 10(4)/mm3. Platelet transfusion was used at the end of cardiopulmonary bypass and on the first postoperative day. There were no problems with hemostasis during the operative procedure and the postoperative course was uneventful. We prefer high-dose transvenous gamma-globulin therapy for ITP prior to open heart surgery as a treatment of choice.

[Valve prostheses of mitral position in children]

Twenty children less than 15 years old of age who had undergone mitral (left-sided atrioventricular) valve replacement before August 1983 have been followed up until October 1988. Fourteen biological valves (B-group) and seventeen mechanical valves (M-group) were used in them. Preoperative conditions had been similar between B- and M-groups. For the B-group, there were one operative death and two late deaths. For the M-group there were no operative death and three late deaths. An actuarial survival rate at ten years was 53.5 +/- 23.3% for the B-group and 85.7 +/- 9.4% for the M-group (not significant). All biological valves were calcified and failed in 27 to 89 months. Three mechanical valves caused thrombosis. There was no other complication for both groups. An event free rate was 0% at eight years for the B-group, however it was 70.6 +/- 11.0% at ten years for the M-group (p less than 0.025). Our data indicates that the mechanical valve is more suitable than the biological valve for children.

[A thoracic aortic aneurysm with respiratory failure caused by the mechanisms of stenosis of the left bronchus and ipsilateral pulmonary artery--report of a case and review of the literature]

Clinical symptoms of thoracic aortic aneurysm vary widely from symptoms resulting from its rupture to those due to compression of surrounding organs. Furthermore, the onset of symptoms is frequently followed by a fatal outcome unless emergency measures are taken. We have recently experienced a patient who developed respiratory insufficiency caused by an aneurysm of the descending thoracic aorta compressing the left primary bronchus and the right pulmonary artery, the former causing ventilatory failure in the left lung and the latter interfering with blood flow in the right lung. The patient underwent emergency prosthetic graft replacement and showed temporary symptom improvement. However, a postoperative complication of esophageal perforation due to ischemic necrosis occurred and eventually caused acute empyema followed by death. The patient was a 48-year-old male who presented with symptoms similar to bronchial asthma. Angiographic examination (iv-DSA) revealed compression of right pulmonary artery by an aneurysm of the descending thoracic aorta. Bronchoscopic findings included extramural stenosis of the left bronchus accompanied by arterial pulsation. As an emergency measure, artificial blood vessel replacement of the descending thoracic aorta was performed. However, the patient developed postoperative acute empyema and died on the 19th postoperative day. Autopsy revealed ischemic necrosis on the esophageal wall where the aneurysmal lesion had touched before operation. This seems to have formed a perforation into the left thoracic cavity and ultimately to have caused acute empyema. Since we believe that the pathogenesis and clinical course observed in this patient is rather rare, the case is reported in accompanied by relevant data from the literature.

[A case of traumatic tricuspid regurgitation]

Tricuspid regurgitation due to nonpenetrating trauma occurred in a 60-year-old male patient who had received chest trauma in a motorcycle accident. He was admitted because of shortness of breath and palpitation on exertion. On admission physical examinations revealed pulsated and dilated jugular veins, hepatomegaly, and systolic murmur. The chest X-ray film showed an enlarged heart and electrocardiograms revealed complete right bundle branch block. Echocardiography demonstrated systolic prolapse of the tricuspid anterior leaflet into the right atrium. Right atrial v wave pressure was 20 mmHg. Tricuspid valve replacement with a Carpentier-Edwards 33 mm using super interpose method was performed successfully 13 years after the trauma. At operation, it was found that the chordae tendineae of the anterior leaflet was ruptured.

Molecular cloning of a human Ca2+-dependent cell-cell adhesion molecule homologous to mouse placental cadherin: its low expression in human placental tissues

P-cadherin is a subclass of Ca2+-dependent cell-cell adhesion molecules present in mouse placenta, where its localization suggests a function of connecting the embryo to the uterus (Nose, A., and M. Takeichi. 1986. J. Cell Biol. 103:2649-2658). We recently identified a human cadherin detected by an mAb capable of disrupting cell-cell adhesion of A-431 cells, and found that it was closely related immunochemically to mouse P-cadherin. Curiously, this cadherin was undetectable in human placenta by immunohistochemical examination (Shimoyama, Y., S. Hirohashi, S. Hirano, M. Noguchi, Y. Shimosato, M. Takeichi, and O. Abe. 1989. Cancer Res. 49:2128-2133). We here report the cloning and sequencing of cDNA clone encoding the human homologue of mouse P-cadherin. The deduced amino acid sequence of the human P-cadherin consists of 829 amino acid and shows striking homology with mouse P-cadherin. On Northern blot analysis, human P-cadherin was scarcely expressed in human placenta in contrast to mouse P-cadherin, which was abundantly expressed in mouse placenta throughout pregnancy, and it was shown that E-cadherin, but not P-cadherin, was the major cadherin molecule in human placenta. Moreover, NIH3T3 cells transfected with human P-cadherin cDNA expressed the functional cadherin molecule, which was identical to the cadherin we had previously identified using the mAb, showing that this molecule really does mediate cell-cell adhesion and that the cadherin we detected immunochemically is undoubtedly human P-cadherin. The results obtained in this study support the idea that P-cadherin plays little role, if any, in Ca2+-dependent cell-cell binding in human placental tissue at least after several weeks of pregnancy.

[Long-term results of mechanical valves in aortic position and biological valves in mitral and tricuspid positions]

The long-term results of patients undergoing aortic valve replacement (AVR) with a mechanical valve (AM), mitral valve replacement with a biological valve (MB), and tricuspid valve replacement (TVR) with a biological valve (TB) operated upon from 1977 to 1988 were retrospectively analysed. A total of 899 patients received 1117 valves (381 AM, 633 TB, 103 TB) with a follow-up 3778 patient-years and 4582 valve-years. A significant incidence of thromboembolism, hemorrhage, and endocarditis was not found among AVR, MVR, TVR, or multiple valve replacement. We found a significantly decreased incidence of survival rate in multiple valve replacement compared with AVR or MVR, and a significantly increased incidence of reoperation in MB compared with AM and TB. We use AM and TB in any adult patients as a first choice. However, we prefer a mechanical valve in the mitral position except in patients over 65 years old, who have a short life expectancy, in whom anticoagulation is thought to be difficult, and who desire a biological valve.

[Biological versus mechanical valves in the mitral position]

The long-term late results of isolated mitral valve replacement before April 1981 were retrospectively evaluated in 54 patients receiving a Hancock valve (HX) with a total follow-up of 424 patient-years (py) and 37 patients receiving a Björk-Shiley valve (BS) with a total follow-up of 366 py. There was no significant difference in regard to preoperative age, cardiothoracic ratio, electrocardiogram, or New York Heart Association functional class between the two groups. All of the BS group and 43 of the HX patients received long-term anticoagulant therapy. No significant difference was notable between the two groups in hospital mortality. Actuarial survival rate excluding hospital deaths was 75.5 +/- 6.7% for the HX group, and 80.8 +/- 7.1% for the BS group at ten years (not significant). There was no significant difference between the two groups in overall incidence of thromboembolism (HX 1.4% py, BS 1.9% py), anticoagulant related bleeding (HX 0.5% py, BS 0.8% py), or endocarditis (HX 0.5% py, BS 0.3% py). Actuarial freedom from reoperation at ten years was 69.6 +/- 8.1% for the HX group, and 93.5 +/- 4.4% for the BS group (p less than 0.01). Event free survival excluding hospital deaths at ten years was 49.2 +/- 8.1% for the HX group, 70.6 +/- 8.3% for the BS group (p less than 0.05). We prefer a mechanical prosthesis except in patients over 65 years old, who have a short life expectancy, in whom anticoagulation is thought to be difficult, and who hope a biological valve.

MTT assay with reference to the clinical effect of chemotherapy

Tumor cells from 40 patients were tested by MTT assay. Five thousand to sixteen thousand tumor cells were plated into 96-well microplates with various concentrations of anticancer agents. After incubation for 48 h, the absorbance of each well was detected with an EIA reader and the effects of the agents were evaluated as positive when the inhibition rate was equal to or more than 50%. Normal cells were also processed under the same conditions, and the absorbance for normal cells was lower than that of tumor cells with statistical significance (P less than 0.05). The efficacy rates of MMC, 5-FU, ADM, and CDDP were 16.7, 8.3, 13.9, and 5.6%, respectively. The overall accuracy of this assay for clinical effects was 83.3%, with one false-positive and five true-negative cases. This MTT assay was also assumed to be useful for in vitro chemosensitivity testing of fresh surgical specimens.

Vector electron paramagnetic resonance spectroscopy with first and second harmonic displays of ferrihemoglobin

Superimposed plots of electron paramagnetic resonance spectra with the first and second harmonic displays of ferrihemoglobin at pH 9.1 and 90 K were measured at 20 degree intervals of phase angle using a phase-sensitive detector. The high spin signal in the g = 6 region was observed in both displays, and a small splitting of the signal was found in the calculated amplitude spectrum of the second harmonic display, with g values of 5.95 and 6.05. Low spin signals were observed at g = 2.55, 2.25 and 1.82 in both harmonic displays. A signal in the g = 2.05 region was observed only in the second harmonic display. The signal is probably associated with the low spin spectrum; however, its origin is obscure.

[Report of 108 patients with valvular heart disease who underwent re-operations through repeated median sternotomy incision]

108 patients who underwent redo median sternotomy between January 1975 and April 1988 were studied to determine factors affecting risk of cardiac reoperations. (1) Seventeen of 108 patients died, yielding an overall mortality of 15.7%. (2) Preoperative diagnosis had a significant correlation with mortality, which was higher with prosthetic valve endocarditis (50.0%) than with all other indications for reoperation. (3) Operative mortality was related to pre-reoperation functional class: 8.7% for New York Heart Association (NYHA) class II, 9.8% for class III and 27.8% for class IV. (4) Based on the degree of urgency, elective reoperation had a mortality of 5.4%, while emergency procedures carried a mortality of 61.5%. (5) Cardiac catheterization information was available in 53 patients. The pulmonary artery pressure was higher in the died group. There were no significant differences in pulmonary capillary wedge pressure and cardiac index between the survived and died. (6) Operation time, aortic cross clamp time and pump run were significantly longer in the died than in the survived group. The died had more blood loss during operative procedure. To decrease operative mortality, technical improvement and increased experience were necessary for surgeons. We prefer to free entirely pericardial adhesion to facilitate mobilization and evacuate air, and to make intra-cardiac procedure more easier and safety. Furthermore early reoperation before irreversible deterioration occurs was necessary since myocardial function was found to be a major determinant of surgical results.

Predictability of in vivo chemosensitivity by in vitro MTT assay with reference to the clonogenic assay

The MTT assay reported by Mosmann is a rapid and convenient colorimetric assay for cellular growth and survival in vitro. In this paper, the MTT assay was modified as a chemosensitivity test, and its potential was investigated. Using 10 human tumor xenografts in athymic nude mice, the predictability of in vitro antitumor effects of drugs using the MTT assay was compared with that using the clonogenic assay. The MTT assay showed excellent reproducibility, and the predictable rate in this assay was 86.7%, with 100% true-positive and 77.8% true-negative rates, almost equivalent to the 90.0% predictable rate of the clonogenic assay. This method also has several advantages with respect to rapidity, quantitation, management of many samples, and cell number required for the assay. Application of this assay to chemosensitivity testing seems to be valuable and useful.

Cadherin cell-adhesion molecules in human epithelial tissues and carcinomas

Two distinct calcium-sensitive cell-cell adhesion molecules were identified in human epithelial tissues and carcinomas using two monoclonal antibodies raised against vulvar epidermoid carcinoma A-431 and human mammary carcinoma MCF-7 and selected on the basis of their activities to disrupt cell-cell adhesion. In immunoblot analysis, these antibodies, designated NCC-CAD-299 and HECD-1, detected main bands of Mr 118,000 and 124,000, respectively. Purified tryptic fragments of the antigen recognized by NCC-CAD-299 showed cross-reactivity with a rabbit antiserum against mouse P-cadherin, indicating that this molecule was the human homologue of P-cadherin. On the other hand, the antigen recognized by HECD-1 showed essentially the same tissue distribution pattern as E-cadherin in the mouse, suggesting that this molecule is the human homologue of E-cadherin. Availability of these monoclonal antibodies to human P- and E-cadherin allowed us to examine their distributions in human tissues immunohistochemically. Both antigens were detected in epithelial tissues, but they showed distributions that were distinct from each other. The antigen recognized by HECD-1 was expressed in almost all epithelial tissues, while distribution of the other one recognized by NCC-CAD-299 was restricted to the basal or lower layers of stratified epithelia in which both antigens were coexpressed. Moreover, immunohistochemical examination of 44 lung carcinomas showed that both molecules were coexpressed in all of them, and suggested that expression of P-cadherin was closely related to the differentiation of carcinoma cells.

Monoclonal antibody highly sensitive for the detection of ras p21 in immunoblotting analysis

Four murine monoclonal antibodies (NCC-RAS-001, -004, -005, -017) reactive with ras p21 were produced by using recombinant c-Ha-ras p21 as an immunogen. Among these antibodies, NCC-RAS-004 was extremely sensitive when used in immunoblotting analysis, facilitating semiquantitative detection of c-Ha-, c-Ki- and N-ras p21 in cell and tissue lysates. In cells carrying a point-mutationally activated ras, p21 with abnormal mobility upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis was clearly detected.

[Antitumor activity of cisplatin and carboplatin against human tumor xenografts serially transplanted into nude mice--with special reference to gastric carcinomas]

Experimental chemotherapy with cisplatin and carboplatin was performed against nine human tumor xenografts serially transplanted into nude mice. Tumors used for the experiment were seven gastric (St-4, St-15, St-40, H-111, SC-2-JCK, SC-6-JCK and Exp-4), one breast (MX-1) and one colon (Co-4) carcinomas. Cisplatin 9 mg/kg and carboplatin 100 mg/kg were administered intraperitoneally (ip). Carboplatin 25 mg/kg was also given ip 4 times every 4 days. The efficacy rates of cisplatin and carboplatin by bolus injection were 77.8% and 66.7% respectively with no statistically significant differences. However, carboplatin was found more effective when given by bolus. The antitumor spectra of both drugs were similar. From these results, these two platinum compounds seemed to be effective against human gastric carcinomas.

A functioning intrapericardial paraganglioma (pheochromocytoma)

A patient with a functioning intrapericardial paraganglioma (pheochromocytoma) that was located at the root of the aorta overlying the right coronary artery and adherent to the right ventricular wall is reported. The tumour was successfully removed under total cardiopulmonary bypass without inducing cardiac arrest.

Molecular motion and order in oriented lipid multibilayer membranes evaluated by simulations of spin label ESR spectra. Effects of temperature, cholesterol and magnetic field

A simulation method to interpret electron spin resonance (ESR) of spin labelled amphiphilic molecules in oriented phosphatidylcholine multibilayers in terms of a restricted motional model is presented. Order and motion of the cholestane spin label (3-spiro-doxyl-5alpha-cholestane) incorporated into egg yolk phosphatidylcholine, dipalmitoylphosphatidylcholine and dimyristoylphosphatidylcholine, pure and in mixture with cholesterol, were studied at various temperatures. With egg yolk phosphatidylcholine identical sets of motional parameters were obtained from simulations of ESR spectra obtained at three microwave frequencies (X-, K- and Q-band). With dipalmitoylphosphatidylcholine and dimyristoylphosphatidylcholine analyses of the spectra show that phase transitions occur in samples containing up to 30 mol % cholesterol. The activation energy for the motion of the spin label is about three times larger above than below the phase transition, indicating a more collective motion in the lipid crystalline state than in the gel state. In the liquid crystalline state the activation energy is larger in the pure phosphatidylcholines than with cholesterol added. Additions of cholesterol to egg phosphatidylcholine induces a higher molecular order but does not appreciably affect correlation times. This is in contrast to dipalmitoylphosphatidylcholine where both order and correlation times are affected by the presence of cholesterol. The activation energies follow the same order as the transition temperatures: dipalmitoylphosphatidylcholine greater than dimyristoylphosphatidylcholine greater than egg yokd phosphatidylcholine, suggesting a similar order of the cooperativity of the motion of the lipid molecules. Magnetic field-induced effects on egg phosphatidylcholine multibilayers were found at Q-band measurements above 40 degrees C. The cholestane spin label mimics order and motion of cholesterol molecule incorporated into the lipid bilayers. This reflects order and motion of the portions of the lipid molecules on the same depth of the bilayer as the rigid steroid portions of the intercalated molecules.