P1016Novel surgical ablation technique using ultrasonic scalpel for atrial fibrillation in mitral valve surgery

Objective

Radiofrequency, cryoablation and cut-and-sew technique have been used for surgical ablation to treat atrial fibrillation. Ultrasonicscalpel is a surgical instrument used to simultaneously cut and cauterize tissue by ultrasound vibration. This device causes minimal lateral thermal tissue damage and increases the tissue penetration depth linearly with time. These features are suitable for surgical ablation for atrial fibrillation. This study evaluated surgical ablation with ultrasonic scalpel for atrial fibrillation.

Methods

From October 2017 to February 2019, 46 patients (mean age: 71.8 years [46–86], 28 male) with mitral valve procedure underwent surgical ablation using ultrasonic scalpel for atrial fibrillation. The ablation lines were carried out with Cox maze procedure or pulmonary vein isolation (PVI) on cardiopulmonary bypass. Endocardial atrial wall was ablated by direct touch with blade in a few seconds at energy level 5. Pathological study of left atrial wall received ablation with ultrasonic scalpel was carried out.

Results

Type of preoperative atrial fibrillation was persistent in 33 and paroxysmal in 13 patients. Mean left atrial diameter was 49.0 mm (35–81). Surgical ablation using ultrasonic scalpel was carried out to left atrium only or PVI in 33 patients and both atria in 13 patients. Mean surgical ablation time was 4 minutes and 21 seconds. Mitral valve repair and replacement were performed in 33 and replacement in 13 patients, respectively. Simultaneous surgery included 43 tricuspid valve repairs, 11 aortic valve replacements, and 7 coronary artery bypass grafting. Cardiopulmonary bypass and aortic cross-clamp times were 142.6 (70–261) and 98.6 (47–202) minutes, respectively. No operative death or perioperative stroke were observed. Thirty-eight patients (82.6%) returned to sinus rhythm immediately after surgery. Sinus rhythm was maintained in 30 patients (65.2%) in the mid-term period with average 142.2 days after surgery (7–426 days). Pathological study showed the atrial walls were not ablated transmurally. No complications including bleeding and tissue injury were observed.

Conclusion

Surgical ablation with ultrasonic scalpel for atrial fibrillation was feasible and provided satisfactory outcomes immediately after surgery and at mid-term. This technique can be performed in a short time without complications. Interestingly, pathological study showed no transmural tissue ablation despite of successful outcomes. This may imply transmural ablation is not necessarily mandatory for surgical ablation. Long-term follow-up are required to evaluate this technique.

[Clinical evaluation of hydrocolloidal dressing in 147 patients undergoing cardiovascular surgery]

Recent evidence has suggested that a moist environment plays an important role in wound healing. Karayahesive, one type of hydrocolloidal dressing, contains natural karaya gum as a hydrophilic gel. We applied hydrocolloidal dressing to operative wounds in 147 patients who underwent cardiovascular surgery from April 2001 through August 2002 to evaluate its clinical usefulness. The dressing was kept on the wounds for 7 days after operation, but was immediately switched to conventional dressing with gauze if there was any problem. A total of 144 patients (98%) had no wound chest infections. Good wound healing was obtained with only 1 dressing, removed 7 days after operation, in 128 patients (87%). In 19 patients (13%), the hydrocolloidal dressing was switched to conventional dressing. In 13 of these patients the hydrocolloidal dressing dissolved naturally or exudation occurred; clinically, there were no local problems; however, 3 patients had infection, 2 had fat necrosis, and 1 had burn injury caused by electrocautery. No patients had skin problems caused by this dressing. We conclude that hydrocolloidal dressing can be used safely and effectively in patients undergoing cardiovascular surgery and reduce the workload of healthcare workers.

[Combined operation for left ventricular aneurysm and ventricular septal perforation with normal coronary arteries; report of a case]

We experienced a rare case of left ventricular aneurysm (LVA) and ventricular septal perforation (VSP) with normal coronary arteries, and had a good outcome by undergoing Dor procedure and direct closure of VSP individually. A 68-year-old female was printed out cardiac systolic murmur. Echocardiogram revealed LVA and VSP, but coronary arteriogram showed no significant stenosis. The apex was incised longitudinally, lateral and parallel to the interventricular groove. VSP was directly closed by 2 pieces of 3-0 polypropylene suture with felt strip. Purse-string stitch with 3-0 polyester suture around the transitional zone between fibrotic tissue and viable tissue was secured to firm fibrous tissue. The residual orifice was closed with an elliptical composite patch of equine pericardial patch and polyester velour with 3-0 polypropylene suture. We considered based on the operative finding that myocardial infarction (MI) led to LVA and VSP. Coronary thrombosis rather than coronary spasm may have provoked MI because spasm provocative test was negative.

[Bilateral coronary ostial stenoses with aortic regurgitation in a patient with syphilitic aortitis]

Syphilitic aortitis is now rare in developed countries and is sometimes overlooked. A 61-year-old man with bilateral coronary ostial stenoses (#5:90%, #1:99%) and Sellers III/IV aortic regugitatioin (AR) induced by syphilitic aortitis presented with chest pain. Preoperative rapid plasma reagin titer and Treponema pallidum hemagglutination test were strongly positive, 256 fold and 191.25 C.O.I., respectively. Aortic valve replacement (AVR) and coronary artery bypass grafting (CABG) with bilateral internal thoracic arteries (ITA) was performed successfully. The angiographic features as follows: 1) coronary artery stenosis is generally limited to the ostia, 2) the grade of stenosis is almost always more than 90%, 3) AR is frequently associated with coronary ostial stenosis. CABG should be performed with ITA, not saphenous vein grafts, to avoid occlusion of the ostium of the saphenous vein graft by syphilitic aortitis. Retrograde cardioplegia should be performed if ostial stenosis is severe.

[Surgical repair of left ventricular free wall rupture using layered fibrin glue sheet and fibrin glue; report of a case]

A 57-year-old man with acute myocardial infarction (#13:90%, #6-#8:75%) was admitted to our hospital after the administration of tissue plasminogen activator. Three hours' after emergent percutaneous transluminal coronary angioplasty, he developed left ventricular free wall rupture in the left circumflex artery area. After bleeding was completely controlled by aortic cross clamping, a three-layered of fibrin glue sheet (TachoComb) with fibrin glue was extensively applied to the ruptured site including the infarcted area. He was discharged on the 25th postoperative day and underwent coronary artery bypass grafting to the left anterior descending artery three weeks later. This experience suggests that the layered TachoComb and fibrin glue are effective for left ventricular free wall rupture.

Giant extracardiac unruptured aneurysm of the sinus of Valsalva: a case report

Extracardiac unruptured aneurysm of the sinus of Valsalva (ASV) is rare and difficult to diagnose accurately by echocardiography or cardiac catheterization preoperatively. A 63-year-old woman, with dyspnea and palpitations, diagnosed with aortic regurgitation (AR) with congestive heart failure and extracardiac unruptured ASV, was referred to our hospital for surgical repair. The unruptured ASV was well visualized by magnetic resonance imaging (MRI), and diagnosed as an extracardiac type. Surgical repair was performed by aortic valve replacement and aneurysmectomy. It was concluded that early surgical repair of extracardiac ASV should be considered to prevent sudden death, and MRI is an accurate and useful method for preoperative diagnosis.

Successful surgical treatment of ventricular tachycardia that induced left ventricular aneurysm in 12-year-old boy

A surgical treatment of ventricular tachycardia (VT) that induced a congenital left ventricular aneurysm (LVA) in a 12-year-old boy was performed. The VT disappeared after epicardial cryoablation and a reinforcement of LVA with a composite patch. Epicardial cryoablation, based on an intraoperative electrophysiologic study (EPS), is effective in treating VT resistant to antiarrhythmia drugs.

Ostial stenosis of coronary arteries after complete replacement of aortic root using gelatin-resorcinol-formaldehyde glue

Coronary ostial stenosis between an interposition graft and coronary artery is rare and fatal. A 46-year-old woman who had reconstruction of both coronary arteries using interposition grafts for type A acute dissecting aneurysm presented with acute chest pain. Emergent coronary artery bypass grafting was done with saphenous vein grafts. Inappropriate use of gelatin-resorcinol-formaldehyde glue can be associated with ostial stenosis in the long term. Transesophageal echocardiography is useful to diagnose ostial stenosis of the coronary arteries.

Gastric cancer with Virchow's and multiple lung metastases showing a remarkable response to preoperative chemotherapy: report of a case

We report herein a rare case with advanced gastric cancer combined with group 4 lymph node and lung metastases that responded remarkably to neoadjuvant chemotherapy. A 65-year-old man was found to have a well-differentiated type 3 gastric cancer that invaded the duodenum locally and was accompanied with Virchow's, para-aortic lymph nodes, and multiple lung metastases based on physical, endoscopic, and radiological examinations. In addition, his carbohydrate antigen (CA) 19-9 was elevated to 3965U/ml, and CA72-4 to 46U/ml. Prior to surgery, he was treated with 5-fluorouracil (5-FU; 500mg/body per day) and low-dose cisplatinum (CDDP; 10mg/body per day) as neoadjuvant chemotherapy for 6 weeks. As a result, a partial response was obtained in all lesions, and CA19-9 and CA72-4 decreased to 463U/ml and 9.4U/ml, respectively. Four weeks after the completion of neoadjuvant chemotherapy, a distal gastrectomy was performed, and a histopathological examination of the resected specimen showed a grade 2 response to chemotherapy. Immunohistochemically, the thymidylate synthase expression level was very low in the tumor tissues, which might account for the good response to the combination chemotherapy with 5-FU and CDDP observed in the present case.

Predicting blood transfusion factors in coronary artery bypass surgery

OBJECTIVE

Blood conservation has become one of the most important issues in cardiac surgery. We clarified preoperative predictors of the need for blood transfusions during coronary artery bypass graft surgery.

METHODS

Subjects were 89 patients--66 men (74%) and 23 women (26%) 40 to 84 years old (mean: 66.2 +/- 8.3 years)--undergoing isolated coronary artery bypass surgery from September 1997 to December 1999. Of these, 66 patients (74%) received transfusion during hospitalization and 23 (26%) did not. Nine risk factors detected by univariate study were entered in a multivariate logistic regression model of the relationship between preoperative variables and blood transfusion.

RESULTS

Independent predictors were emergency surgery (P = .0023), lower hematocrit (P = .0027), older age (P = .0043), and the presence of peripheral vascular disease (P = .0070). Optimal cutoff of hematocrit for blood transfusion was 39% and age 64 years via receiver-operating characteristics curves based on the relation between sensitivity and specificity.

CONCLUSION

Patients older than 64 years with hematocrit less than 39% and/or peripheral vascular disease should be treated routinely using preoperative storage of autologous blood whenever the patient's condition permits. For patients undergoing emergency surgery, further studies are required, including lowering transfusion threshold and using determinants other than hematocrit.

[Postoperative rupture of abdominal aortic aneurysm in patients with ischemic heart disease and other organ disease]

We experienced two cases of rupture of an abdominal aortic aneurysm during the early postoperative period of coronary artery bypass grafting (CABG). A 71-year-old man on hemodialysis (HD) was diagnosed with ischemic heart disease (IHD) and abdominal aortic aneurysm (AAA) of 70 mm in size. After CABG, he developed symptoms of acute pancreatitis and died of rupture of AAA on the 12th postoperative day. A 74-year-old man with early gastric cancer was diagnosed with IHD and AAA of 70 mm. After CABG and gastrectomy, he died of rupture of AAA due to anticoagulant therapy on the 3rd postoperative day. One-stage operation should be performed in patients with IHD, AAA more than 60 mm in size and other organ disease. It is important to control blood pressure and anticoagulant therapy appropriately during the early postoperative period when graft replacement for AAA is not performed simultaneously. Careful observation is required to establish the differential diagnosis of acute pancreatitis and impending rupture of AAA in patients on HD.

[Experiences of minimally invasive great saphenous vein graft harvest using with endopath]

We have experienced 20 cases of minimally invasive great saphenous vein graft harvest using with endoscopy, Endopath, from March 1999. As we experienced cases, we can harvest great saphenous vein graft, about 30-40 cm in size, from only two 4-cm incisions for about 50 minutes. There are no wound infection, pain, and edema. Great saphenous vein graft harvesting with Endopath is less invasive, painless after surgery and makes patients satisfied about cosmetic problem.

Regression of left main coronary ostium stenosis after surgical revascularization and steroid therapy

We describe a patient in whom stenosis of the left main coronary ostium completely regressed after steroid treatment following surgical revascularization. A 46-year-old woman with unstable angina underwent double coronary artery bypass grafting. Although she did not fulfill diagnostic criteria for Takayasu's disease, we began postoperative steroid therapy on postoperative day 14 based on clinical manifestations and histological findings. Coronary angiography 33 days after surgery showed the ostial stenosis of the left main coronary artery had disappeared. Steroid therapy for suspected Takayasu's disease should be considered even after surgical revascularization.

[A case of acute pulmonary embolism fourteen days after hysterectomy]

We describe a 54-year-old female with acute pulmonary embolism. She showed a syncope attack and hypotension fourteen days after hysterectomy for uterine cancer. Preoperative echocardiogram revealed that thrombus in the right atrium was coming and going through the tricuspid valve. Emergent pulmonary embolectomy through the sternotomy under cardiopulmonary bypass was performed 4.5 hours after the diagnosis without homologous blood transfusion. Postoperative perfusion scintigram 20 days after the operation showed normal filling of the both lungs except for the localized defect at the distal portion of the right middle lobe. The patient was discharged on the 22nd postoperative day and she has been followed up with anticoagulation therapy. It is essential that we have the opportunity to salvage an otherwise helpless situation by a high index of suspicion and a prompt surgical intervention.

Anatomic biventricular correction by taking down bicaval Glenn shunt

A 7-year-old boy underwent ventricular and atrial septal defect patch closures, pulmonary valvulotomy, left pulmonary artery dilatation, and bicaval Glenn shunt, which maintained good patency between the superior vena cava and right atrium, because of a reduced right ventricular end-diastolic volume (RVEDV). The RVEDV had increased at 15 years of age; therefore, we performed an anatomic biventricular correction by removing the bicaval Glenn shunt. We found that anatomic biventricular correction becomes possible if RVEDV increases postoperatively.

Left atrial myxoma associated with acute myocardial infarction

We describe a patient with left atrial myxoma associated with acute myocardial infarction. Since hemodynamics were impaired even with the support of an intra-aortic balloon pump, the patient underwent removal of the tumor concomitant with coronary artery bypass grafting to the right coronary artery on the fifth day from infarction onset. In circumstances of life-threatening of myxoma associated with acute myocardial infarction, removal of myxoma with coronary artery bypass should be performed in an acute phase of myocardial infarction.

Crystal structure determinations of oxidized and reduced plastocyanin from the cyanobacterium Synechococcus sp. PCC 7942

The crystal structures of oxidized and reduced plastocyanins from Synechococcus sp. PCC 7942 have been determined at 1.9 and 1.8 A resolution, respectively, at pH 5.0. The protein consists of only 91 amino acid residues, the smallest number known for a plastocyanin, and apparently lacks the mostly conserved acidic patch that is believed to be important for recognition with electron-transfer partners. The protein has two acidic residues, Glu42 and Glu85, around Tyr83, which is thought to be a possible conduit for electrons, but these are neutralized by Arg88 and Lys58. Residue Arg88 interacts with Tyr83 through a pi-pi interaction in which the guanidinium group of the former completely overlaps the aromatic ring of the tyrosine. Reduction of the protein at pH 5.0 causes a lengthening of one Cu-N(His) bond by 0.36 A, despite the small rms deviation of 0.08 A calculated for the backbone atoms. Moreover, significant conformational changes of Arg88 and Lys58, along with the movement of a water molecule adjacent to the OH group of Tyr83, were observed on reduction; the guanidinium group of Arg88 rotates by more than 11 degrees, and the water molecule moves by 0.42 A. The changes around the copper site and the alterations around Tyr83 may be linked to the reduction of the copper.

Crystallization and preliminary X-ray analysis of plastocyanin from cyanobacterium Synechococcus sp. PCC 7942

A plastocyanin from the cyanobacterium Synechococcus sp. PCC 7942 has been crystallized in two different forms by hanging-drop vapour diffusion with ammonium sulfate as precipitant. Form I is hexagonal, space group P61 or P65, with unit-cell dimensions a = b = 34.62 and c = 107.22 A. Form II is tetragonal, space group P41 or P43, with unit-cell dimensions a = b = 43.05 and c = 56.94 A. Form I crystals diffract to 2.5 A using graphite-monochromated Cu Kalpha radiation from a Rigaku RU-300 rotating-anode generator operated at 40 kV and 100 mA. Form II crystals diffract to 1.9 A using synchrotron radiation at beamline BL6A of the Photon Factory (KEK). Molecular-replacement calculations using the structure of plastocyanin from Ulva pertusa have been performed.

[Case report of surgical repair of left ventricular free wall rupture using GRF glue and pericardial patch]

A 73-year-old woman with acute myocardial infarction (Seg. 6: 100%) was admitted to our hospital. She underwent percutaneous transluminal angioplasty (PTCA) and stent insertion to Seg. 6 on that day and anticoagulant therapy with urokinase and heparin was started in CCU. On the 4th day, chest pain developed suddenly and echocardiography revealed cardiac tamponade, so we suspected left ventricular free wall rupture. When blood pressure increased to 100 mmHg in the operating room, the left ventricular free wall rupture became "blow out" type. After establishing extracorporeal circulation, we glued Xenomedica and autologous pericardium using gelatin-resorcin-formaldehyde glue (GRF glue) to the linear tear without damaging the myocardium and coronary arteries and reducing left ventricular volume. Bleeding was completely controlled. This experience suggests that this procedure might be effective for left ventricular free wall rupture.

[Three cases of right-sided active endocarditis with multiple pulmonary infarction]

We have experienced three patients with right-sided active endocarditis combined with multiple pulmonary infarction. Ventricular septal defect (VSD), aortic regurgitation (AR), tricuspid regurgitation (TR) and congestive heart failure were present in case 1. TR was present in case 2. VSD, TR and patent ductus arteriosus were present in case 3. alpha-Streptococcus caused endocarditis in case 1 and 3; Candida albicans caused endocarditis in case 2. Antibotic therapy had no effect in case 2 and 3. Case 1 and 3 developed pulmonary hemorrhage, which resolved before the operation in case 1, but not in case 3. Our three patients underwent surgery and recovered successfully. They were discharged on the 43th, 58th and 32th postoperative day and are presently free of clinical symptoms. These experiences suggest surgery should be undertaken in the following situations: 1. antibiotic therapy has no effect on the infection, 2. hemodynamics are worsening, and 3, pulmonary infarction and pulmonary hemorrhage occur repeatedly.

[The waffle procedure (multiple incision of epicardium) with pericardiectomy for constrictive pericarditis]

Pericardiectomy is the only effective surgical procedure for constrictive pericarditis, but we have often experienced a lack of significant improvement of hemodynamic parameters, this being attributed to the presence of residual constriction. We have had two patients with constrictive pericarditis. In these patients, we decorticated the pericardium as usual, anterior to the bilateral phrenic nerves without cardiopulmonary bypass, and then, multiple longitudinal and transverse incisions were carefully made in the fibrous epicardium, avoiding the predicted course of major coronary branches and the myocardium. At the end of the procedure, the epicardial fibrous surface acquired a waffle-like appearance. With this maneuver, relief of constriction was achieved and the myocardium was able to reexpand, thus obtaining an adequate hemodynamic response. Our two patients recovered fully, and were discharged on the 18th and 19th postoperative day. They are presently free of clinical symptoms.

Heart valve operation in acromegaly

BACKGROUND

Intractable congestive heart failure is known as a serious complication of acromegaly, but valvular heart disease rarely occurs in acromegalic patients. We experienced 5 surgical cases of valvular heart disease associated with acromegaly. We describe the features of those cases in this report.

METHODS

The patient characteristics and operative and pathologic findings were retrospectively studied.

RESULTS

There were 4 men and 1 women. Age at operation was 59 +/- 5.5 years. Cardiac lesions consisted of 1 case of aortic regurgitation associated with mitral regurgitation, 1 of aortic regurgitation, and 3 of mitral regurgitation. Operative procedures consisted of 1 double valve replacement (aortic and mitral valve replacement), 1 aortic valve replacement, and 3 mitral valve replacements. The causes of aortic valvular regurgitation were aortic valvular degeneration and aortic annular dilatation. The causes of mitral regurgitation were chordal rupture and mitral valvular degeneration. Histopathologic examination of the excised valves showed mucopolysaccharide deposits and myxomatous degeneration of the leaflets. The myocardium showed fibrosis of interstitial spaces and endocardium, and disarrangement of muscle fibers.

CONCLUSIONS

We report 5 successful surgical cases of valvular heart disease associated with acromegaly. Earlier operation is recommended for such cases because of acromegalic cardiomyopathy.

[Aortic valve replacement with the Toronto stentless porcine valve in a patient with clipping for cerebral arterial aneurysm]

A 48-year-old man, who had a cerebral arterial aneurysm, was admitted in our institution for operation of aortic valve stenosis. At first, he underwent clipping for cerebral arterial aneurysm under precise management of his hemodynamic condition. After the clipping operation, we performed aortic valve replacement with the Toronto stentless porcine valve because no anticoagulant therapy was ideal for patient with cerebrovascular disease and larger effective orifice area was preferable for stenotic aortic annulus. By means of echocardiography, mean pressure gradient of the aoric valve decreased from 42 mmHg to 22 mmHg after the valve operation. He was discharged from the hospital on the 23rd postoperative day, and he has been doing well without thromboembolic events and bleeding complications for five postoperative months. This experience suggest that the Toronto stentless porcine valve might be one of the valve of choice for patients with aortic valve disease and cerebrovascular disease.

[Simultaneous tricuspid valve operation in patients undergoing aortic and mitral double valve replacement]

In triple valvular surgery, AVR+MVR+TVR or TVP, there are some problems around operation, because patients impaired cardiac function after a long history of the disease and some of them are reoperation cases. The sixty-five patients operated from May in 1980 to June in 1993 were examined. They were divided into two groups, group P and group R, depending upon procedure of tricuspid position. Group P consisted of 51 patients and group R of 14 patients. There were 22 (34%) reoperations. In group P, organic changes in tricuspid valve were mild, however in group R, there were commissural fusion in 8 patients, destruction of leaflet due to infectious endocarditis in one patient, and marked tricuspid annular dilatation in five patients. There was one early death in group R, no early death in group P. Actuarial survival rate at the 10th postoperative year was good as 81.6% in group P and 85.7% in group R. There were no significant differences in operative mortality and actuarial survival between group P and R.

Efficiency of orthotopic xenograft models for human colon cancers

It is feasible to graft human colon cancer tissue into immuno-deficient nude mice, in order to maintain these tumors in vivo. Analysis of the properties tumors under such conditions might increase our knowledge of their biological characteristics. Xenografts are usually implanted into subcutaneous tissue, a site easily accessible for both graft procedure and observation of tumor growth. However these subcutaneous tumors are usually non-invasive and fail to metastasize. To override these limitations we, as others, have tried to improve the tumor xenograft model by transplanting tumors into their original location, designated as the orthotopic site. Transplanted into the cecum of nude mice, human colon cancers were frequently locally invasive and developed liver metastases. These transplantations may be done by injection of colon cancer cell suspensions into the cecal wall. Alternatively, orthotopic implantations of histologically intact tissue were performed and the thus-obtained tumors were more metastatic than tumors obtained after tumor cell injections. The chemosensibility of tumors xenografted into their orthotopic site was different from that of their subcutaneously implanted counterpart. This, added to the enhancement of invasive and metastatic properties, leads us to conclude that colon cancer xenografted into the caecum might be more representative of the clinical situation. We have reviewed the literature and report on the possibilities and limitations different models of colon cancer in vivo.

Sustained tyrosine phosphorylation of p140trkA in PC12h-R cells responding rapidly to NGF

The PC12h cell, a subclone of PC12 cells, has considerable activities of tyrosine hydroxylase (TH) and choline acetyltransferase (ChAT) and shows an NGF-induced increase in both enzyme activities. The TH activity and its inducibility by NGF in PC12h cells were stably maintained in the passage of > 200 generations whereas the ChAT activity was not. We isolated a new cell line, PC12h-R (originally clone 8), from a long-term culture of PC12h cells. PC12h-R cells still showed the considerable TH activity, but not the ChAT activity, and maintained the inducibility of TH activity by NGF. Thus, the responses of PC12h-R cells to NGF were similar to those of chromaffin cells and sympathetic neurons. PC12h-R cells were found to extend neurites and differentiate into sympathetic neuron-like cells in response to NGF much more rapidly than PC12h cells. In addition, PC12h-R cells showed sustained NGF-induced tyrosine phosphorylation of p140trkA and several cellular proteins, including 42-, 44- and 54-kDa proteins, in comparison with PC12h cells. We suggest that the NGF-induced sustained tyrosine phosphorylation signal in PC12h-R cells may be correlated closely with their rapid NGF-induced differentiation into neuron-like cells.

Enhancement of choline acetyltransferase activity in coculture of rat septal and hippocampal neurons

We report that choline acetyltransferase (ChAT) activity and neuronal survival were enhanced in rat septal neurons cocultured with hippocampal neurons. The enhancement of ChAT activity also occurred as a result of the addition of hippocampal conditioned medium (HpCM). When septal neurons from embryonic day 17 (E17) rats were cocultured with hippocampal neurons, ChAT activity was increased 2-fold compared with homogeneous culture of septal neurons. By contrast, no increase in ChAT activity was observed in coculture of septal and neocortical neurons. Treatment with HpCM obtained from cultured E19 rat hippocampal neurons enhanced the ChAT activity of E17 rat septal neurons. The enhancement of ChAT activity caused by coculture with hippocampal neurons and that caused by the addition of HpCM were not blocked by the addition of anti-nerve growth factor (NGF) antibody, suggesting that NGF, which is known to increase the ChAT activity of septal neurons both in vivo and in vitro, did not participate in the increase of ChAT activity. These findings indicate that possible target-derived neurotrophic factor(s), other than NGF, from hippocampal neurons enhance(s) the ChAT activity of septal neurons.

High oxygen atmosphere for neuronal cell culture with nerve growth factor. I. Primary culture of basal forebrain cholinergic neurons from fetal and postnatal rats

Cholinergic neurons cultured from postnatal days 11-13 (P11-P13) rat basal forebrain showed better survival in the culture condition using a 50% O2 atmosphere with and without nerve growth factor (NGF) than in a low (10 or 20%) O2 atmosphere. Except for the culture at a low cell density, the beneficial effect of the highly oxidized culture condition was found in the culture from P3 neurons, but not from embryonic day 18 neurons. The survival of microtubule-associated protein 2 (MAP2)-positive neurons in culture from P3 basal forebrain regions was more enhanced in a 50% O2 atmosphere than in 20% and also 10% O2 atmosphere. The viable number of the MAP2-positive neurons in a 10% O2 condition was about half of that in a 20% condition. These results suggest that the response of the cultured neurons to an incubator O2 concentration changes during the neuronal development in CNS from fetal to postnatal stages.

Monitoring of acetylcholine released from postnatal rat basal forebrain cholinergic neurons cultured on membrane filter by cell bed perfusion system and HPLC-ECD

A method for the determination of release of endogenous neurotransmitter from cultured neurons has been developed. Basal forebrain cholinergic neurons from postnatal rats were cultured on polyethyleneimine-coated membrane filter with nerve growth factor. The membrane filter, on which the neurons lived and extended neurites, was packed in a cell bed chamber for a closed perfusion. The perfusate was fractionated and the content of acetylcholine released from cultured neurons was measured by high-performance liquid chromatography-electrochemical detection (HPLC-ECD). Acetylcholine release evoked by glutamate and high K+ was 1.5- and 3-fold greater than the spontaneous level. This method for the determination of the neurotransmitter released from cultured neurons is very advantageous for investigating regulation of transmitter release in central neurons.

Nerve-growth-factor-dependent and cell-density-independent survival of septal cholinergic neurons in culture from postnatal rats

We have established a primary neuronal cell culture technique from the postnatal (P11 to P15) rat CNS to study the nerve growth factor (NGF) response to basal forebrain cholinergic neurons. The survival of septal cholinergic neurons in culture was monitored both by the determination of choline acetyltransferase activity and by counting acetylcholinesterase-positive cells. Cells obtained from postnatal septal regions were found to require a plentiful oxygen supply during the dissociation of the cells. NGF-mediated survival of the septal cholinergic neurons was similarly observed in the cultures by using different plating cell densities up to 12.5 X 10(5) cells/cm2. These results suggest that the promotion by NGF of cell survival in culture is independent of plating cell density.

Synthesis and secretion of human nerve growth factor by Saccharomyces cerevisiae

The DNA coding for human nerve growth factor (hNGF) was chemically synthesized and introduced into Saccharomyces cerevisiae. Expression and secretion of hNGF was obtained by use of the yeast phosphoglycerate kinase-encoding gene promoter and the pre-pro sequence of the yeast alpha-mating factor. Immunoblotting with antiserum raised against a protein A-hNGF fusion protein, allowed the detection of an immunoreactive material secreted into the culture medium. A preparation from the culture medium, partially purified by ion-exchange column chromatography, stimulated neurite outgrowth from rat pheochromocytoma PC12h cells.

Increase in choline acetyltransferase activity in septum of rats after transient forebrain ischemia: a possible role of factors released in the hippocampus

Choline acetyltransferase (ChAT) activity increased in rat septum 2 weeks after a transient forebrain ischemia. Extracts were prepared from hippocampus in which CA1 pyramidal neurons had been selectively destroyed by the ischemic insult. ChAT activity in septal neuronal cultures treated with these extracts for 6 days was significantly higher than that in control cultures.

Intracellular storage and evoked release of acetylcholine from postnatal rat basal forebrain cholinergic neurons in culture with nerve growth factor

Cholinergic neurons from the septum area, the vertical limb of the diagonal band of Broca, and the nucleus basalis of Meynert of postnatal 13-day-old rats were cultured with or without nerve growth factor (NGF) conditions. Total choline acetyltransferase (ChAT) activities, acetylcholine (ACh) contents, and survival numbers of cholinergic neurons in culture from each of three distinct regions were increased by NGF treatment, but little difference was found in cellular ChAT activities and ACh contents obtained in cultures with or without NGF. The result shows that NGF promotes the survival of cholinergic neurons from 13-day-old rats. Furthermore, the release of ACh from cultured neurons was investigated. The cells cultured with NGF showed a larger increase of the high K+-evoked ACh release than those cultured without NGF. However, NGF had no effect on spontaneous release. This suggests that NGF could regenerate and sustain the stimulation-evoked release mechanisms of ACh in cultured cholinergic neurons from postnatal rats.

Interleukin-6 as a neurotrophic factor for promoting the survival of cultured basal forebrain cholinergic neurons from postnatal rats

Human recombinant interleukin-6 (IL-6, B-cell stimulating factor-2) was capable of supporting neuronal survival in cholinergic neuron culture, prepared from 10-day-old rat brain septal region. Cell survival of the cultured cholinergic neurons was estimated by measuring the remaining choline acetyltransferase (ChAT) activities after 6 days of culture. IL-6 at a concentration of 5 ng/ml maintained a more than 3-fold higher ChAT activity in the culture as compared with that in cultures without IL-6. The maximal dose of IL-6 was near 50 ng/ml. The concomitant addition of mouse nerve growth factor (NGF) and IL-6, both at maximal doses, had a synergistic effect on cholinergic cell survival. These results indicate that IL-6 can act as a neurotrophic agent, independent of the action of NGF, supporting neuronal survival of cultured postnatal rat septal cholinergic neurons. On the other hand, IL-6 did not affect the differentiation of the cultured embryonic rat septal cholinergic neurons, differently from the differentiation action by NGF.

Nerve growth factor promotes survival of retrogradely labeled hippocampus-projecting neurons in the rat basal forebrain in vitro

The effect of nerve growth factor (NGF) on the survival of neurons projecting to the hippocampus from developing medial septum and vertical limb of the diagonal band was studied in vitro. The neurons had previously been labeled retrogradely in vivo with fluorescent latex microspheres. The microspheres were injected bilaterally into the hippocampus of 5-day-old rats. Twenty to 24 h after the injection, cells from the basal forebrain were dissociated with papain and cultured for 3-5 days. The number of microsphere-labeled neurons in the culture with supplementation of NGF was much greater than that without NGF. The result clearly indicates a survival-promoting effect of NGF on these projection neurons.

Transplantation of fetal and early postnatal rat septal cholinergic neurons cultured in serum-free and serum-containing medium with nerve growth factor

Fetal rat (E17-E19) septal neurons were cultured in a defined, serum-free medium for 6-8 days with or without nerve growth factor (NGF) and transplanted into the hippocampus or the surrounding ventricle of 28 adult rats denervated of its septal input by a fimbria-fornix transection. The cholinergic septal neurons, which were visualized by acetylcholinesterase (AChE) histochemistry, always survived in transplantation to the adult brains from nearly pure neuronal cultures. Although choline acetyltransferase (ChAT) activity of septal neurons in culture was greatly increased (5.59-fold) by the addition of NGF to the defined medium, this ChAT induction appeared to have little effect on the subsequent survival or growth of the septal neurons after transplantation. These results demonstrate that survival of cultured fetal septal cholinergic neurons following transplantation is not dependent upon the presence of NGF or serum- or glia-derived factors during the preliminary culture. Postnatal rat (P4) septal neurons cultured for 5 days in serum-containing medium with NGF were also successfully transplanted in one of 3 cases.

Nerve growth factor increases the intracellular content of acetylcholine in cultured septal neurons from developing rats

The effects of nerve growth factor (NGF) on the intracellular content of acetylcholine (ACh) in cultured septal neurons from developing rats have been examined. The content of ACh could be measured by using HPLC and electrochemical detection (HPLC-ECD), coupled with an immobilized enzyme column. This method of determination is very simple and rapid, and is highly sensitive. The content of ACh and the activity of choline acetyltransferase (ChAT) in cultured postnatal day 1 (P1) septal neurons grown on an astroglial "feeder" layer was increased during the period of cultivation by the addition of NGF. The activities of ChAT and the content of ACh increased in a dose-dependent manner in direct relationship to the different amounts of NGF employed. These effects of NGF, i.e., elevating the intracellular content of ACh, accompanied by an increase in activity of ChAT, also were confirmed in the P1 septal organotypic cultures. Additionally, embryonic day 17 (E17) septal neurons in a serum-free medium displayed a similar responsiveness to NGF with respect to the elevation in the content of ACh and the increase in activity of ChAT. These results suggest that intracellular levels of ACh are likely to be regulated by NGF in a fashion similar to that of the activity levels of the biosynthetic enzyme.

The appearance of a highly digitalis-sensitive isoform of Na+,K+-ATPase during maturation in vitro of primary cultured rat cerebral neurons

Immature neurons from the cerebra of 17-day rat fetuses were cultured, and changes in Na+, K+-ATPase activity of the cells were investigated during maturation in culture. The Na+, K+-ATPase activity of the particulate fraction from the cells increased during the course of culture, up to 0.38 +/- 0.01 (mumol/min/mg protein) (= 8.25 +/- 0.85 (mumol/min/mg DNA] by day 13 in culture. The values were more than 3 and 19 times those of the 17-day fetal cerebrum on the bases of protein and DNA, respectively. The enzyme in the immature neurons was mainly a weakly digitalis-sensitive form in terms of the inhibition pattern of the Na+,K+-ATPase activity by strophanthidin. Along with the maturation in vitro of the neurons, a highly digitalis-sensitive form of the enzyme was shown to appear and increase by the biphasic inhibition patterns of Na+,K+-ATPase activity by strophanthidin and of K+ uptake activity by ouabain. The enzyme activity of the highly sensitive form overwhelmed that of the weakly sensitive form by day 13 in culture. In cultured rat cerebral astrocytes, the enzyme was judged to be only the weakly digitalis-sensitive form from the simple inhibition patterns of the Na+,K+-ATPase and K+ uptake activities by digitalis.

Nerve growth factor promotes survival of cultured magnocellular cholinergic neurons from nucleus basalis of Meynert in postnatal rats

One of the possible causes of Alzheimer's disease is thought to be a lack of nerve growth factor (NGF), which plays an important role in the neuronal differentiation and cell survival of basal forebrain cholinergic neurons. In the present study, we report for the first time a direct in vitro effect of NGF on the survival of magnocellular cholinergic neurons of the nucleus basalis of Meynert. A dissociated culture of cholinergic neurons was prepared after dissecting out the nucleus from vibratome slices of postnatal rat forebrain. After culturing the neurons of this nucleus from 2-week-old rats for 6 days, the cell number of viable acetylcholinesterase-positive cholinergic neurons in the presence of NGF was found to be greater than that in the absence of NGF. Also, more extensive and denser acetylcholinesterase-positive neurites were observed in the NGF-treated culture. Higher activities of choline acetyltransferase were also observed in the NGF-treated culture. Cellular choline acetyltransferase activity, which was calculated by dividing the enzyme activity by the viable number of acetylcholinesterase-positive neurons for each well, was almost the same with or without NGF. These results mean that NGF enhanced cholinergic neuronal survival and cholinergic neurite regeneration, but did not induce cellular choline acetyltransferase activities.

Developmental change in the nerve growth factor action from induction of choline acetyltransferase to promotion of cell survival in cultured basal forebrain cholinergic neurons from postnatal rats

Nerve growth factor (NGF), a well-characterized target-derived growth factor, has been postulated to promote neuronal differentiation and survival of the basal forebrain cholinergic neurons. In the present paper, we demonstrate that a developmental change in NGF action occurs in postnatal rat basal forebrain cholinergic neurons in culture. Firstly, NGF acts as maturation factor by increasing choline acetyltransferase (ChAT) activity and acts later as a survival factor. In dissociated cell cultures of septal neurons from early postnatal (P1-4) rats, ChAT activities were increased by the addition of NGF. That is, ChAT activities in P1 septal cells cultured for 7 days was increased 4-fold in the presence of NGF at a concentration of 100 ng/ml. However, the number of the acetylcholinesterase (AChE)-positive neurons was not significantly different between these groups. In contrast, septal neurons from P8 to P14 rats showed different responses to NGF. Although the P14 septal neurons in culture for 7 days without NGF lost about half of the ChAT activity during a 7-day cultivation, cells cultured with NGF retained the activity at the initial level. The number of AChE-positive neurons counted in cultures with NGF was much greater than the number without NGF. These results suggest that, during the early postnatal days, the action of NGF on the septal cholinergic neurons in culture changes from induction of ChAT activity to the promotion of cholinergic neuronal cell survival. During this developmental period in vivo, septal neurons are terminating their projections to the hippocampal formation. Similar NGF-regulated changes in cholinergic neurons were observed in cultured postnatal neurons from vertical limb of diagonal band. An analogy has been pointed out between the neuronal death of the basal forebrain cholinergic neurons and a similar neuronal death in senile dementia, especially Alzheimer's type. The work reported here might present a possibility that NGF could play a role in preventing the loss of the basal forebrain cholinergic neurons in this disease.

Septal cholinergic neurons from postnatal rat can survive in the dissociate culture conditions in the presence of nerve growth factor

The survival effect by nerve growth factor (NGF) on the cholinergic neurons of postnatal rat septal neurons in culture was examined. When the septal neurons from 10 to 12-day-old rats were cultured without NGF, the activities of choline acetyltransferase gradually decreased during the period of cultivation. The addition of NGF to the culture prevented the decline of activities. And, the number of acetylcholinesterase-positive neurons in culture with NGF was found to be more than that without NGF, after 5 days in culture. These results suggest that NGF promotes the survival of septal cholinergic neurons from postnatal rats in culture.

Differential effects of nerve-growth factor and glioma-conditioned medium on neurons cultured from various regions of fetal rat central nervous system

When nerve-growth factor (NGF) was added to 17-day fetal rat central nervous system (CNS) septal neurons in culture using a defined medium, choline acetyltransferase (ChAT) activity was greatly induced. However, glioma-conditioned medium (GCM), which is expected to contain cholinergic neurotrophic factor(s) different from NGF, did not affect the ChAT activity of the cultured septal neurons. On the contrary, ChAT activity of 19-day fetal rat hippocampal neurons in culture was increased by the addition of GCM but not by NGF. These phenomena were confirmed in septal and hippocampal neuronal cultures obtained from the same embryonic day, i.e., 18-day fetal rat. The NGF-mediated increase in ChAT activity of cultured septal neurons was culture-time dependent (2.3-fold increase after 3 and 3.5-fold increase after 6 days in culture) and NGF-dose dependent (the ED50 value was 0.8 ng/ml). The effect of NGF was completely abolished by the addition of specific anti-NGF antibodies. The differential effects of NGF and GCM on several other cultured cholinergic neurons from 17-day fetal rat spinal cord, striatum, brainstem and amygdala were measured. NGF tended to increase ChAT activities of cultured striatal and amygdala neurons but not cultured spinal cord and brainstem neurons. GCM increased ChAT activities in the latter two cultures, while having no effect on the former cultures. Although the extent of increase of NGF-mediated ChAT activities of cultured striatal and amygdala neurons were low, NGF-mediated increase of the striatal ChAT activity showed the pattern resembling that of cultured septal neurons as to time-course, dose-dependency and anti-NGF antibody sensitivity. NGF did not affect the tyrosine hydroxylase activity in the cultured brainstem catecholaminergic neurons.