[A case report of St. Jude medical aortic valve prosthesis thrombosis]

We report a case of successful semi-emergent redo aortic valve replacement for thrombosed prosthetic valve. Patient was a 59-year-old male who had undergone aortic valve replacement of St. Jude Medical prosthetic valve and open mitral commissurotomy 14 years ago. He suffered from pneumonia with hemosputum and admitted a neighbor hospital. But he was reffered to our medical center because of progressing dyspnea. We found the immobility of one of the leaflets of the prosthetic valve by cinefuluoroscopy. He was also diagnosed as prosthetic valve thrombosis and mitral valve restenosis using ultrasonic echocardiography. The thrombi were developed on the hinge of one of the leaflets, and they might be formed during the time he had got inappropriate anticoagulation therapy at the former hospital. We emphasise the importance of strict anticoagulation control for the patients valve replaced.

Protein phylogeny of translation elongation factor EF-1 alpha suggests microsporidians are extremely ancient eukaryotes

Partial regions of the mRNA encoding a major part of translation elongation factor 1 alpha (EF-1 alpha) from a mitochondrion-lacking protozoan, Glugea plecoglossi, that belongs to microsporidians, were amplified by polymerase chain reaction (PCR) and their primary structures were analyzed. The deduced amino acid sequence was highly divergent from typical EF-1 alpha's of eukaryotes, although it clearly showed a eukaryotic feature when aligned with homologs of the three primary kingdoms. Maximum likelihood (ML) analyses on the basis of six different stochastic models of amino acid substitutions and a maximum parsimony (MP) analysis consistently suggest that among eukaryotic species being analyzed, G. plecoglossi is likely to represent the earliest offshoot of eukaryotes. Microsporidians might be the extremely ancient eukaryotes which have diverged before an occurrence of mitochondrial symbiosis.

[Replacement of descending thoracic aorta using open proximal anastomosis under hypothermic circulatory arrest]

Open proximal anastomosis under hypothermic circulatory arrest was applied to eleven consecutive patients with descending aortic diseases. These patients included five aortic dissections and six thoracic aortic aneurysms. Fourth and 7th intercostal spaces were opened by left posterolateral thoracotomy. Cardiopulmonary bypass was established by right atrial drainage via femoral vein and main pulmonary artery. Arterial blood was perfused via femoral artery. The descending aorta was opened under hypothermic circulatory arrest with anal temperature of 20 degrees C, and the anastomosis of the proximal site of the graft was performed with bloodless field. After the proximal anastomosis was finished, the main graft was clamped and perfused via the branch of the graft. The distal anastomosis was performed during circulatory arrest of the lower body. Mean circulatory arrest time of the upper body was 31 min, and that of the lower body was 37 min. Nine of the patients arrive without any major complications, but two of them died due to postoperative low cardiac output syndrome and postoperative pneumonia. Open proximal anastomosis under hypothermic circulatory arrest may be useful for the replacement of the diseased descending aorta due to dissection or aortic aneurysm with mural thrombi because of the advantage of non-clamping anastomosis with bloodless surgical field.

[Cerebral infarction after the cardiovascular operation]

From January, 1990 through July 1994, 615 adult patients were undergone cardiovascular operation under the cardiopulmonary bypass. Sixteen patients were suffered perioperative cerebral infarction. The etiology of the cerebral infarction was evaluated on the pre and postoperative brain CT findings by the neurologists. In the 283 coronary artery bypass operations, 4 patients suffered watershed infarction (WS) and 4 cerebral embolism. In the 252 valve operations, one WS and one embolism. In the 80 thoracic aortic operations, 5 WS and one embolism, respectively. The risk factors of WS were the elderly, emergency, the longer operative period, and the longer cardiopulmonary bypass period. The risk factor of the embolism were male, preoperative cerebral infarction, the calcified finding of the ascending aorta by the chest CT. It is important to take preventive strategies against the watershed infarction.

Evolution of the active sequences of the HpaI short interspersed elements

Ninety-nine members of the salmonid HpaI and AvaIII families of short interspersed repetitive elements (SINEs) were aligned and a general consensus sequence was deduced. The presence of 26 correlated changes in nucleotides (diagnostic nucleotides) from those in the consensus sequence allowed us to divide the members of the HpaI family into 12 subfamilies and those of the AvaIII family into two subfamilies. On the basis of the average sequence divergences and the phylogenetic distributions of the subfamilies, the relative antiquity of the subfamilies and the process of sequential changes in the respective source sequences were inferred. Despite the higher mutation rates of CG dinucleotides in individual dispersed members, no hypermutability of CG positions was observed in changes in the source sequences. This result suggests that sequences of SINEs located in a nonmethylated or hypomethylated genomic region could have been selected as source sequences for retroposition and/or that some CG sites are the parts of recognition sequences of retropositional machineries.

Effect of temporary occlusion of the hepatic vein on dual blood in the liver: evaluation with spiral CT

PURPOSE

To evaluate the contribution of hepatic veins to the dual blood supply in the liver under temporary hepatic venous occlusion.

MATERIALS AND METHODS

Selected hepatic veins in 23 patients with liver tumors were temporarily occluded with a balloon catheter. Computed tomography (CT) arteriography, CT during arterial portography (CTAP), or both were performed with a spiral technique with and without temporary occlusion of a hepatic vein.

RESULTS

After hepatic vein occlusion, a well-demarcated, wedge-shaped area of hypoattenuation was seen at CTAP and/or hyperattenuation was seen at CT arteriography in the following regions: left lobe (left hepatic vein), ventral part of the anterior segment and the medial segment except for the ventromedial part (middle hepatic vein), dorsal part of the anterior segment and the ventral part of the posterior segment (right hepatic vein), and dorsocaudal part of the right lobe (inferior right hepatic veins).

CONCLUSION

After hepatic venous occlusion, the portal veins become draining veins and the occluded area is supplied with arterial blood alone.

Segmented areas of increased attenuation in the liver caused by right adrenal tumors: CT features

OBJECTIVE

Our goal was to describe attenuation differences bordered by a straight line in the right hepatic lobe on enhanced CT in patients with right adrenal tumors and to discuss the cause of this appearance.

MATERIALS AND METHODS

Three patients showing attenuation differences bordered by a straight line were discovered in the CT files of 26 cases of right adrenal tumor over 3 cm in diameter. All CT scans were examined by incremental dynamic study.

RESULTS

Two patients had large zone of hyperattenuation in the right lobe bordered with a straight line intersecting both anterior branches of the right portal vein and the inferior vena cava (IVC). A third patient and one of the two patients mentioned already had zones of relative hyper- and hypoattenuation in the medial portion of the posterior hepatic segment, respectively. All three patients had large right adrenal tumors, which severely compressed the right hepatic vein near its confluence with the IVC and/or the IVC in or below its intrahepatic portion. The distribution of attenuation differences was similar to the hyperattenuation at CT arteriography or perfusion defect at CT arterial portography under temporary balloon occlusion of the right hepatic vein and inferior right hepatic vein, respectively.

CONCLUSION

Straight-bordered attenuation differences within the right hepatic lobe at dynamic CT can be caused by compression of the right hepatic vein by large right adrenal tumors.

Malignant schwannoma arising in patients with von Recklinghausen's disease: report of two cases and the comparison of mast cells between benign and malignant portions

We described two cases of malignant schwannoma arising in patients with von Recklinghausen's disease and examined the mast cells infiltrated into histologic sections. One of the two cases histologically revealed apparent mast cell infiltration in some areas of malignant schwannoma as well as in the benign neurofibroma. The malignant lesion demonstrated significantly increased percentages of degranulated mast cells over the benign lesion using FITC-avidin staining. In an electron microscopic study, mast cells in the malignant lesion displayed empty granules, piecemeal degranulation, and canaliculi structures suggesting activation. These findings were not observed in the benign lesion. The other patient histologically showed no mast cells in the malignant lesion, although the benign neurofibroma in the patient disclosed numerous mast cells. The first patient had neither recurrence nor distant metastasis. On the other hand, the second patient without mast cells in the histology had multiple distant metastases.

Left ventricular end-systolic volume index in patients with ischemic cardiomyopathy predicts postoperative ventricular function

BACKGROUND

We investigated the usefulness of the preoperative left ventricular end-systolic volume index (LVESVI) as a predictor of postoperative ventricular function.

METHODS

We retrospectively reviewed the records of 310 patients who underwent coronary artery bypass grafting and identified 20 patients with ischemic cardiomyopathy with a preoperative ejection fraction less than 0.30. We determined the preoperative and postoperative ejection fraction, LVESVI, and left ventricular enddiastolic volume index using biplane left cineventriculography. Patients were divided into groups depending on whether their preoperative LVESVI was less than 100 mL/m2 (group A, n = 10) or greater than 100 mL/m2 (group B, n = 10).

RESULTS

The mean ejection fraction increased significantly after coronary artery bypass grafting in group A from 0.25 +/- 0.05 to 0.40 +/- 0.09 (p < 0.01), but did not change significantly in group B (0.26 +/- 0.05 versus 0.23 +/- 0.06). The mean LVESVI decreased significantly in group A from 83.2 +/- 13.7 to 61.7 +/- 20.4 mL/m2 after operation (p < 0.05), but did not change significantly in group B (124.7 +/- 21.0 versus 121.5 +/- 37.6 mL/m2). In group B, 4 patients had signs of congestive heart failure during the follow-up period and had to be rehospitalized.

CONCLUSIONS

The mean ejection fraction improved significantly after coronary artery bypass grafting in patients with a preoperative LVESVI less than 100 mL/m2, despite the presence of a global left ventricular ejection fraction less than 0.30. Our results suggest that the preoperative LVESVI predicts the postoperative status and left ventricular function in patients with ischemic cardiomyopathy.

[Clinical significance of selective cerebral perfusion with cold blood on the brain protection]

In 42 patients with thoracic aortic disease, a selective cerebral perfusion with 16 degrees C cold blood was applied for the brain protection during the repair of the thoracic aorta. The surgical repair consisted of the replacement of the ascending aorta (9 cases), the ascending aorta and aortic arch (12 cases), the aortic arch (18 cases), and the aortic arch and descending aorta (3 cases). Twenty-two patients of them (52%) required emergency surgery and four patients died due to postoperative complications including visceral organ ischemia (2 cases) and multiple organ failure (2 cases). The mortality rate of this group was 18.2% (4/22 cases). In elective surgical classes, one patient died due to intraoperative coronary embolism. The mortality rate of this group was 5.0% (1/20 cases). No postoperative obvious brain defect was observed except one old patient (85-year-old female) with ruptured aortic arch who already had the brain infarction preoperatively. She died due to multiple organ failure with unconsciousness. Other patients including the patients with long cerebral perfusion (> 180 min) recovered well and returned to normal daily life. The selective cerebral perfusion with cold blood was easy to prepare and demonstrated the superb efficacy of brain protection in the patient.

Straight border sign of the liver: spectrum of CT appearances and causes

Attenuation differences bordered by straight lines within the liver (the straight border sign) are sometimes seen at computed tomography (CT). This phenomenon, which was demonstrated with unenhanced CT over a dozen years ago, does not represent a hepatic mass and is often associated with vascular compromise. Major causes of the straight border sign include fatty liver, confluent fibrosis, radiation hepatitis, and vascular abnormalities such as tumor thrombus, thromboembolus, compression, and arterioportal shunt. The frequency of this finding increases when intense contrast enhancement is used, especially when contrast material is administered via the superior mesenteric artery (CT during arterial portography) or hepatic artery (CT arteriography). The use of spiral CT is apparently increasing the chances of encountering this sign in daily practice. To correctly interpret the straight border sign, one should consider the distribution (anatomic vs nonanatomic), the attenuation (low vs high), and the use and technique of contrast enhancement.

[Supra-annular mitral valve replacement for a patient with prosthetic valve endocarditis]

Supraanular mitral valve replacement with a 29 mm CarboMedics prosthetic valve was performed for a 58-year-old patient of prosthetic valve endocarditis. He has received mitral valve replacement 2 years ago, and was admitted because of high fever and severe heart failure diagnosed mitral regurgitation due to valve dehiscence. An annular abscess was observed and the new 29 mm CarboMedics prosthetic valve was sutured to the left atrial wall approximately 10 mm above the original annulus in order to secure the firm suturings for valve implantation and to left the infected annulus intact. The patient, however, underwent reoperation because of valve dehiscence from atrial wall 6 months after surgery. Infectious abscess at the native mitral annulau was observed to be completely cured, and a mitral prosthesis was implanted at the annulus. The patient is discharged under satisfactory condition.

Role of transforming growth factor-beta 1 on platelet-induced enhancement of endothelin-1 production in cultured vascular endothelial cells

We and other investigators obtained evidence that platelets stimulate endothelin-1 (ET-1) production at both message and protein levels in vascular endothelial cells (ECs), and that platelet-derived transforming growth factor-beta 1 (TGF-beta 1) is responsible for this stimulation. In the present study, we examined the effects of acidification or heat treatment, known to activate latent TGF-beta 1, on the platelet supernatant-induced ET-1 production in cultured porcine aortic ECs. Supernatant of platelets (6.0 x 10(8) platelets/ml) aggregated by adenosine diphosphate contained large amounts of TGF-beta 1, but were almost in a latent form, and the proportion of active TGF-beta 1 in the supernatant was increased markedly in the case of acidification or heat treatment. These treatments also significantly potentiated the supernatant-induced stimulation of prepro ET-1 mRNA expression and the ET-1 release in ECs. Purified TGF-beta 1 also enhanced ET-1 release, dose-dependently, but the enhancement declined at the higher concentrations. Thus, powerful stimulation of ET-1 production by platelet supernatant after acidification or heat treatment cannot be explained only by increments in active TGF-beta 1. The supernatant-induced stimulation of ET-1 synthesis was significantly inhibited by concomitant treatment of TGF-beta 1 neutralizing antibody, but this inhibition was incomplete even at a concentration that abolished TGF-beta 1-induced maximal stimulation. These results suggest that platelet-induced stimulation and subsequent acidification and heat treatment-induced potentiation on endothelial ET-1 production depend closely on release and activation of TGF-beta 1 derived from platelets.(ABSTRACT TRUNCATED AT 250 WORDS)

[Dislodgement of the ringed-graft--a case report]

A 70-year-old man underwent replacement of the distal aortic arch which contained a huge aneurysm using a ringed graft. He died suddenly of hemoptysis 54 months following the operation. An autopsy revealed dislodgement of the spool on the posterior aspect of the aorta. Histologic examination of the dislodged portion of the ring showed complete disruption of the intima and elastic fibers of the media. There were minimal histologic changes in the anterior portion of the anastomotic site. It is postulated that the long, kinked graft might have caused the late ring dislodgement.

Evaluation of the antithrombogenicity of a new microdomain structured copolymer

A new antithrombogenic material was studied, fluorine-acryl-styrene-urethane-silicone (FASUS) copolymer, the theoretical basis of which attributed to its hydrophilic and hydrophobic microdomain structure. In this series of experiments, the blood compatibility of this copolymer was evaluated in vitro and ex vivo. For the in vitro evaluation, a whole blood clotting test and the microsphere column test were performed. For the ex vivo evaluation, two series of shunt tests in rabbits were performed, one was the arterioartery (A-A) shunt model, and the other was the arteriovenous (A-V) shunt model. The antithrombogenicity was assessed by measuring the shunt obstructive time in the A-A shunt experiment. The A-V shunt experiment was assessed by measuring the circulating platelet counts, platelet aggregability, activated partial thromboplastin time (APTT), and prothrombin time (PT). In the whole blood clotting test, FASUS revealed the significantly longer blood clotting time than that of the control glass tubings (19.7 +/- 1.0 versus 6.5 +/- 0.7 min, p < 0.001). In the microsphere column test, the coated group had a 30% reduction of the platelet number in the eluted blood in contrast with a marked decrease of 70% in the control group (p < 0.05). In the ex vivo A-A shunt experiment, the occlusion time for the FASUS-coated group was significantly longer than that of the control (109.7 +/- 17.3 versus 3.0 +/- 0.4 min, p < 0.05). The A-V shunt experiment showed that the FASUS copolymer suppressed the decrease in platelet counts and tended to improve prolonged APTT compared with that of the control. Clinically, in 25 patients, we placed coated FASUS copolymer into the cannulas for use in percutaneous cardiopulmonary support (PCPS) procedures. There was no evidence of thrombus on the blood contacting surface and no thromboembolism in major organs clinically or upon postmortem examination. In summary, this new copolymer may be effective in preventing thrombus formation in vitro, ex vivo, and in clinical situations.

Antithrombotic effect of TA-993, a novel 1,5-benzothiazepine derivative, in conscious rats

Since reported experimental models of thrombosis are not suitable for comparison of several drugs by oral administration, we developed a convenient model for this purpose by applying direct current through an intravascular electrode. In conscious rats, which were implanted with anodal electrodes in the abdominal aorta on the day before the experiment, application of 200 microA of direct current induced the formation of a platelet-rich thrombus around the intravascular electrode. Using this model, we studied the antithrombotic effect of the novel antiplatelet agent TA-993, (-)-cis-3-acetoxy-5-(2-(dimethylamino)ethyl)-2,3-dihydro-8-methyl-2-(4- methylphenyl)-1,5-benzothiazepin-4(5H)-one maleate, and compared its effect with other antiplatelet agents. TA-993 at doses of 30 mg/kg, p.o. or more by single administration or at doses of 10 mg/kg or more by repeated administration dose-dependently suppressed the thrombus formation. Aspirin (10 mg/kg, p.o. or more), cilostazol (100 mg/kg, p.o.) and ticlopidine (30 mg/kg, p.o. or more) also suppressed the thrombus formation by single administration. These results suggest that TA-993 has a comparable antithrombotic effect with other antiplatelet agents, and thus it is a possible remedy for thrombotic and embolic diseases.

Proinflammatory cytokine levels in patients undergoing cardiopulmonary bypass. Does lung reperfusion influence the release of cytokines?

Proinflammatory cytokines have been implicated in mediating tissue injury after cardiopulmonary bypass. Causative factors of inflammatory response after cardiopulmonary bypass include contact of the blood with the extracorporeal circuit and heart-lung reperfusion injury when discontinuing bypass. To evaluate proinflammatory cytokine release during cardiopulmonary bypass, plasma levels of interleukin-6, 8, and monocyte chemoattractant factor were measured in the radial artery (for systemic blood) and left atrium before and after cardiopulmonary bypass. A total of 13 patients were studied, with no deaths or complications. In both radial artery and left atrium, interleukin-6, 8, and monocyte chemoattractant factor rose significantly after cardiopulmonary bypass (p < 0.05 versus before cardiopulmonary bypass). These changes may have been caused by removal of the aortic cross clamp and recommencement of artificial ventilation, which result in reperfusion of the pulmonary capillary beds. There were no differences in cytokine levels after cardiopulmonary bypass in the radial artery and left atrium. This result suggested that lung reperfusion injury after cardiopulmonary bypass may not be the major causative factor of the release of proinflammatory cytokines.

Proposal of a working left heart model with a heterotopic transplantation technique in rats

BACKGROUND

A heterotopically transplanted rat heart model described by Ono and Lindsey in 1969 has been widely used as a fundamental animal model of heart transplantation. However this "nonworking" model is greatly different from the orthotopic heart in view of left ventricular work, in which the experimental results obtained may not always reflect the clinical setting with an orthotopic transplanted "working" heart. We herein propose a new "working" left heart model in rats using a heterotopic abdominal transplantation technique by modifying the method of Ono and Lindsey.

METHODS

First, a donor heart graft and a recipient were prepared in the conventional fashion. Second, the donor heart was tailored by the ligation of main pulmonary artery and the removal of tricuspid valve and interatrial septum. Third, the ascending aorta and right atrium of the donor heart were anastomosed to the infrarenal abdominal aorta and to the inferior vena cava of the recipient, respectively. Consequently, the left atrium and ventricle of heart graft were loaded with the blood from the right atrium through the interatrial communication.

RESULTS

This surgical procedure required an average of 58 minutes and had negligible operative risk. The donor left ventricle produced a systolic blood pressure almost equal to the recipient's aortic pressure and maintained vigorous beat.

CONCLUSIONS

This model is easily reproducible and would be useful for various studies on heart transplantation.

A new retroviral vector for detecting mutations and chromosomal instability in mammalian cells

A retroviral vector carrying both forward (neo) and backward (herpes simplex virus thymidine kinase or HSV-TK gene) selection markers was constructed as a substrate for mutational assay in mammalian cells. The cells infected with this virus are first selected with G418, mutagenized and then selected with the anti-herpes drug acyclovir (ACV). Since HSV-TK, but not the host TK, is capable of converting ACV to a toxic metabolite, cells retaining the intact HSV-TK gene fail to survive, while the cells carrying a mutated HSV-TK gene or which have lost the gene can form colonies in the presence of ACV, making it possible to detect the genetic defects in a positive manner. It is also possible to discriminate between small mutations and large deletions by checking the presence of the linked marker, neo. As a model experiment, we prepared an uncloned pool of rat fibroblast cells (CREF) infected with this virus and irradiated them with increasing doses of ultraviolet light. Dose-dependent increases in the number of ACV-resistant colonies were observed. Structural analysis of the HSV-TK gene in these clones revealed point mutations or small deletions in the majority of the cases. Since it requires no pre-existing genetic markers in the host cells, this system may be used for a wide variety of mammalian cells and provides a useful tool to assess both their susceptibility to various mutagens and their genomic instability.

[A long survival case of brain tumor considered as a metastatic tumor]

A case of long survival of brain tumor (well differentiated adenocarcinoma) was reported. A 55-year-old man was admitted in January, 1986, because of a one month history of progressive headache, dizziness and gait disturbance. CT scans revealed an enhancing tumor in contact with the falx in the right frontal lobe. The tumor was totally removed. The histopathological diagnosis was that of a well differentiated adenocarcinoma. The primary site of the adenocarcinoma was not detected. No chemotherapy or radiation therapy was given. Four years and 7 months after surgery CT scans demonstrated a recurrent tumor as a bilaterally expanding falx meningioma. Nearly total removal of the tumor was again performed and diagnosed as adenocarcinoma. Examinations to detect the primary site and other metastatic lesions were negative again. On May 1993, the patient died because of the intracranial dissemination of tumor without extracranial lesions. The period from the first operation to his death was 7 years and 5 months. This is a case of long survival of intracranial cancer, which was considered as a metastatic tumor, though the primary site and other metastatic lesions were not detected. The tumor in this case showed the atypical features of a metastatic adenocarcinoma. For example, the primary and recurrent tumors resembled a parasagital or falx meningioma in shape and they grew slowly. Therefore, there is a possibility that the tumor was actually a primary adenocarcinoma, which might have arisen from the embryologically migrated cells of the mucous membrane or from ectopic epithelial cells.

Enhancement of norepinephrine and angiotensin II-induced renal effects by NG-nitro-L-arginine, a nitric oxide synthase inhibitor

We investigated whether endogenous nitric oxide (NO) has a role as an inhibitory modulator of norepinephrine (NE)- and angiotensin II (Ang II)-induced renal effects in anesthetized dogs. Intrarenal arterial infusion of NE (100 ng/kg/min) or Ang II (10 ng/kg/min) decreased renal blood flow (RBF), glomerular filtration rate (GFR) and urine formation. The NE- or Ang II-induced renal effects were augmented by the intrarenal administration of a NO synthase inhibitor, NG-nitro-L-arginine (NOARG), at doses (10 and 40 micrograms/kg/min) which did not affect the mean arterial blood pressure and heart rate. The stimulating activity of NOARG on NE- or Ang II-induced renal effects were abolished by the simultaneous administration of L-arginine, a NO precursor. These findings suggest that endogenous NO, which is probably generated within the kidney, functions as an inhibitory modulator in NE- or Ang II-induced renal vasoconstriction and antidiuresis.

Delayed platelet adhesion/aggregation at sites of endothelial injury in mouse cerebral arterioles after transient elevations of blood pressure and shear

BACKGROUND AND PURPOSE

Prior research showed that injection of angiotensin II (Ang II) produces a transient elevation of blood pressure (BP) and shear in pial arterioles. This inhibited platelet adhesion/aggregation at a site of subsequently injured endothelium. The present study attempted to confirm the Ang II finding with a different method of endothelial injury, to test the hypothesis that the effect on adhesion/aggregation was a consequence of prolonged release of "classic" endothelium-derived relaxing factor (released by acetylcholine [Ach]; EDRFACh) produced by the preceding transient elevation in shear, and to show with the use of norepinephrine rather than Ang II that the effect of a preceding elevation of BP was independent of the pressor agent used.

METHODS

Focal platelet adhesion/aggregation was elicited in cerebral surface (pial) arterioles by producing minimal endothelial damage with a helium-neon laser/Evans blue dye technique. Vessels were observed by intravital microscopy. We recorded the time required for the laser to elicit adhesion/aggregation in control mice and in mice given Ang II in a dose of 16 micrograms/25 g IP. This dose produces an abrupt and significant elevation of BP and shear, which return to baseline levels in less than 30 minutes. Laser/dye damage of endothelium and resultant adhesion/aggregation of platelets were not induced until after BP and shear returned to basal levels. The effect of topical Ang II on damage-induced adhesion/aggregation was also tested. In addition, mice injected with Ang II were treated with either topical indomethacin 40 micrograms/mL or topical Ng-monomethyl L-arginine (L-NMMA; 10(-6) mol/L) in an effort to prevent the preceding increase in shear from inhibiting subsequent adhesion/aggregation. Finally, norepinephrine instead of Ang II was used to transiently raise BP (and shear) in an effort to delay subsequently induced adhesion/aggregation.

RESULTS

Platelet adhesion/aggregation at the injured site was significantly delayed by a prior transient rise in shear produced by either Ang II or norepinephrine. Locally applied Ang II failed to influence adhesion/aggregation, although a previous study showed that such Ang II reaches the endothelium. Locally applied indomethacin had no effect on inhibition of platelet adhesion/aggregation, but locally applied L-NMMA prevented the prior transient elevation of shear from inhibiting adhesion/aggregation at a subsequently injured site.

CONCLUSIONS

Elevation of BP with consequent elevation of shear inhibits local platelet adhesion/aggregation even when the latter is initiated by endothelial damage produced after return of shear to basal levels. The direct action of Ang II on endothelium is not responsible for the effect on adhesion/aggregation, and indeed the effect is independent of the pressor agent. The pharmacological data, together with the literature, support the hypothesis that increased shear causes an increased release of EDRFACh, which may continue for at least some minutes after return of shear to normal levels.

[Coronary artery perforation after directional coronary atherectomy (DCA)]

Directional coronary atherectomy (DCA) was performed on a 51-year-old man with unstable angina due to a 90% stenosis of the proximal side of the left anterior descending artery (LAD). A coronary angiography after the DCA showed the coronary artery perforation communicating with the pericardial space. He suffered cardiac tamponade and cardiogenic shock, and was taken to the emergent surgical intervention. The both side of the perforation was ligated to control active bleeding and coronary artery bypass grafting to the distal portion of the LAD was performed. It is stated that the incidence of tamponade resulting from vessel perforation after DCA is extremely rare.

[Systemic-pulmonary artery shunt using Golaski graft: trial for measurement of the shunt flow]

For the systemic-pulmonary artery shunt operation, the modified Blalock-Taussig shunt was the first choice for procedure in our institution. Since 1990, Golaski knitted Dacron graft (4 or 5 mm in diameter) was used for the prosthesis. Ex-vivo flow calibration of the electromagnetic flow meter (Nihon Koden, MFV-3100) to Golaski graft showed good correlation between the real flow and value measured by the electromagnetic flow meter. Shunt flow was measured in the consecutive clinical fifteen cases. The shunt flow per body surface area of the patient who required additional shunt operation was 721 ml/min/m2 and one patient in whom the congestive heart failure developed after the shunt operation, had the shunt flow of 3,022 ml/min/m2. The adequate shunt flow in these cases was ranged from 745 to 2,820 ml/min/m2 (mean +/- 1 SD, 1,490 +/- 587.8). Therefore we performed the systemic-pulmonary artery shunt operation using Golaski graft to get the shunt flow of 1,000 ml/min/m2 (approximately a third of cardiac index) for the guide of good results.

[Surgical treatment of type A aortic dissection based on the location of the entry]

From 1987 to February of 1994, 42 cases of acute aortic dissection and 31 cases of chronic dissection have been operated in out institution. Our surgical technique for the treatment of aortic dissection is a tubular graft replacement following a resection of the segment of aorta containing the intimal tear. The location of the entry was, therefore, important to determine the extension of graft replacement and to select the circulatory support method during operation. 52%, 33% and 14% of cases in acute aortic dissection had entries in ascending, arch and descending aorta, respectively. Entries of 52%, 32% and 16% of cases in chronic dissection located in ascending, arch and descending aorta, respectively. In cases with the entry in ascending aorta, ascending aorta and partial aortic arch replacement was performed in 12 and 10, respectively, for acute dissection, whereas more extensive graft replacement procedure was selected for chronic dissection including complete arch replacement in three cases and two of them had concomitant Bentall type operation. Likewise, with the entry in aortic arch, partial arch replacement was performed more often in 9 than complete arch replacement in 5 for acute dissection, on the other hand, complete arch replacement procedure tended to be preferable in 6 cases for chronic dissection. For retrograde dissection with the entry in descending aorta, ascending aorta and complete arch replacement were performed in 4 and 6 cases, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of phosphoramidon on endothelin-1 and big endothelin-1 production in human aortic endothelial cells

Using cultured human aortic endothelial cells, we examined the effects of phosphoramidon, an endothelin converting enzyme (ECE) inhibitor, on the release of endogenous endothelin-1 (ET-1) and big endothelin-1 (big ET-1), and on the generation of ET-1 from exogenously applied big ET-1. Phosphoramidon, at concentrations of 10(-6) to 2 x 10(-4) M, caused a biphasic alteration of the ET-1 release, i.e., at lower concentrations of the drug, there were slight but unexpected increases of the release, whereas higher concentrations led to a decrease which is due to the drug-induced inhibition of ECE. The former effect appears to be based on the inhibition of ET-1 degradation by neutral endopeptidase 24.11 (NEP), since kelatorphan, a specific NEP inhibitor, produced a similar increasing effect on ET-1 release. Phosphoramidon enhanced the big ET-1 release from the cells in a concentration-dependent manner. When high concentrations of phosphoramidon were added, there was a dramatic increase in the release of big ET-1, which cannot be explained only by the drug-induced inhibition of ECE. This increase in big ET-1 release appeared to be partly due to a transient stimulation of the expression of prepro ET-1 mRNA. The amount of ET-1 generated from exogenously applied big ET-1 was markedly decreased by phosphoramidon in a concentration-dependent manner. In a similar fashion, phosphoramidon markedly inhibited ECE activity of the membrane fraction of cultured cells. Thus, ET-1 generation from exogenously applied big ET-1 reflects the functional phosphoramidon-sensitive ECE activities in human aortic endothelial cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Sulfamethizole absorption test for the assessment of gastric emptying. Comparison with scintigraphic method

BACKGROUND

To investigate whether the sulfamethizole absorption test can be applied for the assessment of gastric emptying, we measured comparatively plasma sulfamethizole concentration and gastric emptying as determined by scintigraphy in 15 subjects.

METHODS

After the ingestion of a solid-liquid meal that contained sulfamethizole and radioisotope (technetium-99m-labeled diethylenetriaminepentaacetic acid), the plasma sulfamethizole concentrations were measured every 15 to 60 min up to 180 min. The initial emptying time (duration after ingestion until 10% reduction in radioactivity of the stomach) and the exponential curve in the cumulative reduction of radioactivity were used as indicators of gastric emptying.

RESULTS

The initial emptying time was significantly correlated with the sulfamethizole concentration at 15 min after ingestion (r = -0.64, p < 0.05). A close correlation was observed between the rate of decrease in radioactivity and sulfamethizole concentration at 60 min after ingestion (r = 0.80, p < 0.001).

CONCLUSIONS

The sulfamethizole absorption test can be used for the evaluation of gastric motility. Two points of measurement, 15 and 60 min after ingestion, are sufficient to demonstrate the initial and subsequent gastric emptying.

Interaction between nitric oxide and angiotensin II on antidiuresis and norepinephrine overflow induced by stimulation of renal nerves in anesthetized dogs

We examined the effects of NG-nitro-L-arginine (NOARG) on antidiuresis and norepinephrine (NE) overflow in anesthetized dogs, induced by renal nerve stimulation (RNS), with or without blockade of an action of endogenous angiotensin II (AII) on the AT1 receptors by losartan. RNS (2.5-5.0 Hz) caused significant reductions in renal blood flow (RBF), glomerular filtration rate (GFR), filtration fraction (FF), urine flow (UF), and urinary excretion of sodium (UNaV) and increases in the differences in renal arteriovenous NE concentrations (NEC). Intrarenal arterial (i.r.a.) infusion of NOARG (40 micrograms/kg/min) significantly decreased RBF and UF, and increased FF, but did not alter GFR. When losartan 100 micrograms/kg/min was infused simultaneously, NOARG reduced RBF, UF, and GFR but had no effect on FF. With high-frequency RNS, NOARG enhanced the RNS-induced decreases in RBF, GFR, UF, and UNaV and the increases in NEC. During losartan infusion, NOARG-induced enhancements on renal actions in response to RNS were observed in a manner qualitatively similar to that without losartan. Most likely endogenous nitric oxide (NO) plays the role of inhibitory modulator of renal noradrenergic neurotransmission. Enhancement of renal noradrenergic neurotransmission induced by NO blockade is likely to be independent of an action of endogenous AII on the AT1 receptors.

[Spatial and temporal alteration of the dual supply of the hepatic circulation with transient occlusion of the hepatic veins: spiral volumetric CT during arterial portography and arteriography]

To elucidate the contribution of hepatic veins to the blood flow of liver, CT arterial portography and/or arteriography was performed in eight patients having hepatocellular carcinoma with transient occlusion of the hepatic vein and eight without occlusion. In each patient with occlusion of the hepatic vein, CT showed a well-demarcated fan-shaped area of low density during arterial portography and increased density during arteriography in the corresponding area. Hepatic vein occlusion could result in the pooling of arterial blood in the liver parenchyma. Transient segmental hepatic venous occlusion might improve the results of transcatheter arterial infusion and transcatheter arterial embolization for liver tumors.

Protein synthesis and rapid recovery of endothelium-dependent dilation after endothelial injury of pial arterioles

A laser-dye technique is known to injure selectively microvascular endothelium in situ. With the use of the arterioles on the surface of the mouse brain (pial arterioles), the endothelial injury is manifest by loss of several endothelium-dependent responses, including the dilation produced by topical application of acetylcholine (ACh), bradykinin (BK), and calcium ionophore A-23187. The responses normally recover by 60 min following injury. The present study shows that inhibitors of protein synthesis prevent the recovery. Either actinomycin D (Act-D; 1 mg/kg) or cycloheximide (CX; 10 mg/kg) was injected intraperitoneally 35 min before the light-dye injury. The CX was used in separate studies with ACh, BK, and ionophore. In each study, recovery of the endothelium-dependent dilation failed to occur 60 min after injury, while recovery occurred in contemporary vehicle-treated controls. Act-D was used in separate studies of ACh and BK. Again, recovery of endothelium-dependent dilation was prevented. Neither CX nor Act-D inhibited the response to ACh in uninjured vessels. Thus response to ACh was intact in such arterioles 90 min after the injection of CX or Act-D. CX was also given to uninjured mice and was found to have no inhibitory action on the response to ionophore 90 min later. CX and Act-D inhibit protein synthesis by very different mechanisms, inhibition of translation and of transcription, respectively. Because both prevented recovery of the endothelium-dependent responses, we conclude that one or more rapidly synthesized proteins are required for the recovery.

[Successful cardiac surgery using normothermic cardiopulmonary bypass in an elderly patient with cryoglobulinemia]

The case of 70-year-old woman with cryoglobulinemia who underwent urgent operation for angina pectoris and mitral regurgitation is reported. Three bypass grafts and mitral valvuloplasty were performed under normothermic cardiopulmonary bypass with continuous warm blood cardioplegia. The postoperative course was uneventful. Normothermic cardioplegia requires further study as a technique for managing patients with cold autoimmune diseases such as cryoglobulinemia who require cardiopulmonary bypass.

[Esophageal perforation by alkalis--a case report with conservative therapy]

In May 1993, a 59-year-old woman attempting suicide with toilet detergent (1% sodium hydroxide) was hospitalized as an emergency case. She developed sudden high fever (38-39 degrees C) on the 26th admission day. Thereafter diagnosis of left pyothorax due to perforation on caustic esophageal ulcer was made. Subsequent to thoracentesis continuous dranage of the left thoracic cavity ceased the fever after three days. Oral intake began on the 28th and extubation of the dranage was done on the 42nd after admission. Following hospital course of the patient was uneventful and the patient was discharged on the 111th day after admission. Esophagofluoroscopy taken at 6 months after discharge revealed no esophageal stenosis, and the patient returned to full social activities in good health.

Involvement of transforming growth factor-beta 1 for platelets-induced stimulation of endothelin-1 production

1. Possible mechanisms by which platelets stimulate the production of endothelin-1 (ET-1) in vascular endothelial cells (EC) were investigated. 2. A supernatant of platelets stimulated the expression of prepro ET-1 mRNA, followed by an increased secretion of ET-1 from cultured EC. These responses were markedly enhanced by pretreatment of the platelets with thrombin, at a concentration which did not influence the ET-1 production in EC. A platelet suspension, separated from cultured EC by a permeable nylon membrane, also markedly stimulated the ET-1 secretion from EC. 3. Endothelin-1 production enhanced by the platelet supernatant, with or without thrombin pretreatment, correlated with the active transforming growth factor-beta 1 (TGF-beta 1) concentrations in the supernatant. The supernatant-induced increase in ET-1 secretion from the EC was markedly suppressed by TGF-beta 1 neutralizing antibody. 4. We tentatively conclude that platelets stimulate the endothelial ET-1 production by releasing a bioactive diffusible substance, mainly TGF-beta 1.

[Preoperative assessment of aortic dissection by three-dimensional CT angiography]

In 21 patients with aortic dissection including 12 patients with acute aortic dissection, aortic lesions were evaluated preoperatively by newly developed three-dimensional CT angiography (3 D-CTA) using helical scan CT. Rapid and safe three-dimensional evaluation of aortic dissection was achieved with no complications. Three-dimensional structure of aortic dissection was well reflected in the image of 3D-CTA. Preoperative three-dimensional evaluation was useful to determine and proceed the operative procedure for the repair of aortic dissection. All patients were alive and results of surgical treatments were excellent. Intimal flaps and entries were visualized by multiple threshold display (MTD) method of 3D-CTA. Multiple threshold display method is an important three-dimensional reconstructive method and 3D-CTA may be a new useful and powerful diagnostic modality for aortic dissection.

[Reoperation for recurrent chondrosarcoma of the pulmonary trunk]

A 71-year-old woman who had progressive dyspnea and edema two years after resection of a pulmonary trunk chondrosarcoma was diagnosed as severe obstruction to the pulmonary trunk due to the recurrent tumor. Magnetic resonance examination following the intravenous administration of Gd-diethylenetriamine pentaacetic acid (DTPA) revealed striking contrast enhancement within the lesion of the pulmonary trunk sarcoma. At reoperation, the recurrent mass was identified within the same site of the pulmonary trunk and total resection of the tumor and replacement of the pulmonary trunk with prosthetic graft was performed utilizing a cardiopulmonary bypass. There have been very few reports on replacements of pulmonary trunks for pulmonary artery sarcomas. It is reported that the prognosis of the pulmonary trunk sarcoma is extremely poor, however, this patient has undergone thoracotomies twice within two years and continued to be symptom-free without distant metastatic lesions.

Species-specific amplification of tRNA-derived short interspersed repetitive elements (SINEs) by retroposition: a process of parasitization of entire genomes during the evolution of salmonids

Fourteen members of the Hpa I subfamilies of tRNA-derived SINEs in particular salmonid species were isolated from genomic libraries of chum salmon, kokanee, coho salmon, masu salmon, and steelhead. Alignment of the sequences of these 14 members, together with those of 4 members already published, 3 of which were previously demonstrated to have been amplified specifically in certain lineages, revealed the presence of five subfamilies with particular diagnostic nucleotides. The amplification of members of the same subfamily in different salmonid lineages and the amplification of members of different subfamilies in the same salmonid lineage suggest that multiple dispersed loci were responsible for amplification or, alternatively, that SINEs were transmitted horizontally between species. These two possibilities are not mutually exclusive. Our results also indicate that the Hpa I SINEs in salmonids behave like parasites. The amplification of these SINEs is ongoing and continues to shape the evolution of salmonid genomes.

Safety evaluation of lipase G from Penicillium camembertii

Lipase G, a partial glycerides eliminating enzyme produced by Penicillium camembertii, was subjected to safety evaluation studies to establish its safety when used as a processing aid in the food industry. The toxicological studies on the enzyme included a 90-day gavage study with rats, a mutagenicity study using bacteria, and a pathogenicity study using mice. The no-adverse-effect level from the 90-day gavage toxicity study was 2000 mg/kg body weight/day for rats. There was no evidence of mutagenic potential. The micro-organism was evaluated for pathogenicity using mice and classified as a non-pathogen. Results indicate that the production and use of lipase G may be regarded as safe for the enzyme production worker and the consumer.

[Evaluation of the addition of counterpulsation to the partial left ventricular-femoral bypass for limitation of evolving myocardial infarction]

The effect of adding counterpulsation to a partial left ventricular bypass was evaluated in a canine model of acute myocardial ischemia by using a myocardial staining method. To establish a left ventricular bypass, a catheter consisting of bypass tube (90 cm in length and 15 Fr in inner diameter) and an accompanying intraaortic balloon as a single apparatus (Integrated Cardioassist Catheter; ICAC) was introduced into the left ventricle via the abdominal aorta. The left ventricular bypass was adjusted to 1 L/min. with or without counterpulsation with the aid of a centrifugal pump and IABP console. The use of the ICAC that provided pulsatile left ventricular bypass tended to raise the mean aortic pressure and cardiac output. Reduction of the tension time index was noted with the use of the ICAC in contrast to the control. And increment of the DPTI/TTI ratio was observed with the use of the ICAC in contrast to the control and partial left ventricular bypass alone. While the percentages of the region at risk were similar [17.3 +/- 9.5% (control), vs. 16.4 +/- 3.4% (partial left ventricular bypass alone) vs. 16.9 +/- 5.2% (ICAC)], the percentages of infarct sizes were reduced due to the use of counterpulsation. [61.9 +/- 12.2% (control), vs. 57.5 +/- 3.9% (partial left ventricular bypass alone) vs. 16.8 +/- 6.0% (ICAC)]. These results revealed that the addition of counterpulsation alleviates afterload reduction to the partial left ventricular bypass and was more beneficial to the reduction of the infarct size than partial left ventricular bypass alone.

[Perforation of the right ventricular wall and extraction into the left thoracic cavity by a permanent endocardial pacemaker lead: a case report]

A 80-year-old woman with right ventricular wall perforation and extraction into the left thoracic cavity by a permanent endocardial pacemaker (PM) lead was presented. The patient underwent an insertion of a permanent endocardial lead into the apex of the right ventricle for the treatment of sick sinus syndrome. The right ventricular perforation of the PM lead was incidentally diagnosed by recognizing it into the left thoracic cavity three months after the operation. Another PM lead could be inserted without removal of the former one.

Improved detection of small insulinomas with intravenous dynamic CT

OBJECTIVE

To evaluate the usefulness of intravenous dynamic CT in demonstrating angiographically negative insulinomas.

MATERIALS AND METHODS

Two patients with endocrinologic evidence of insulinoma were examined with intravenous bolus-dynamic CT.

RESULTS

Angiographically negative insulinomas as small as 5-7 mm were demonstrated unequivocally as enhancing nodules.

CONCLUSION

Intravenous dynamic CT using larger amounts of contrast material can improve detection of small (< 1.0 cm) insulinomas.

[Operative strategy for redo heart valve operation]

Thirty-five redo heart valve operations were performed between Jan. 1990 and Dec. 1993 in Jichi Ohmiya Medical Center. Previous operations were mitral valve replacement (MVR) in 19, closed mitral commissurotomy in 1, open mitral commissurotomy in 6, aortic valve replacement (AVR) in 5, ASD repair in 3, VSD repair in 1. Thirty (85.7%) were in NYHA functional class III or less, and 5 (14.3%) were in functional class in IV. Twenty-three patients had undergone MVR, 5 AVR, 4 MVR+AVR, 2 TVR (TAP), 1 Cabrol operation, and 8 patients had undergone concomitant tricuspid valve repair. Emergent operation was none. Overall operative mortality was 5.7% (2/35), as the cause of death was low output syndrome. Chest CT was available for the evaluation of the distension of right atrium and right ventricle. Catastrophic hemorrhage by the injury of ascending aorta or right atrium during redo sternotomy was 4, but that was not the cause of death. We emphasize the necessity of the exposure of the femoral artery and the preparation for cardiopulmonary bypass before sternotomy. The extent of dissecting adhesion should be determined case by case respectively under consideration of the risk of cardiovascular injury and postoperative large bleeding. Furthermore the cannule of SVC or IVC with cuff was useful for the cases with strong adhesion.

Anti-CD31 delays platelet adhesion/aggregation at sites of endothelial injury in mouse cerebral arterioles

The arterioles on the surface of the mouse brain (pial arterioles) were observed by in vivo microscopy. A focus of minor endothelial damage was produced in a single pial arteriole in each mouse by briefly exposing the site to a helium neon laser after an intravenous injection of Evans blue. Mice were injected 10 minutes before injury with a monoclonal antibody (MAb) to mouse CD31, also known as platelet endothelial cell adhesion molecule. This treatment doubled (P < .01) the time required for the laser to produce a recognizable platelet aggregate. In additional experiments, an MAb to mouse CD61 and an MAb to mouse intercellular adhesion molecule 1 had no effect. The data support previous observations indicating that platelet adhesion/aggregation in this model is induced by endothelial injury without exposure of basal lamina. The data are consistent with the hypothesis that the endothelial injury exposes or activates a platelet endothelial cell adhesion molecule on the endothelium which is blocked by the MAb directed against CD31. This may be the first demonstration of an effect of an anti-platelet endothelial cell adhesion molecule on platelet endothelial cell adhesion molecule on platelet adhesion/aggregation in vivo.

MRI in subacute combined degeneration

We describe a patient with clear lesions in the spinal cord on MRI due to subacute combined degeneration. T2-weighted images clearly showed abnormal high signals in the posterior columns, which disappeared on recovery from the disease.

Pharmacological studies on a new dihydrothienopyridine calcium antagonist, S-312-d. 5th communication: anticonvulsant effects in mice

S-312, S-312-d, but not S-312-l, L-type calcium channel antagonists, showed anticonvulsant effects on the audiogenic tonic convulsions in DBA/2 mice; and their ED50 values were 18.4 (12.8-27.1) mg/kg, p.o. and 15.0 (10.2-23.7) mg/kg, p.o., respectively, while that of flunarizine was 34.0 (26.0-44.8) mg/kg, p.o. Although moderate anticonvulsant effects of S-312-d in higher doses were observed against the clonic convulsions induced by pentylenetetrazole (85 mg/kg, s.c.) or bemegride (40 mg/kg, s.c.), no effects were observed in convulsions induced by N-methyl-D-aspartate, picrotoxin, or electroshock in Slc:ddY mice. S-312-d may be useful in the therapy of certain types of human epilepsy.

The effects of NG-nitro-L-arginine, a nitric oxide synthase inhibitor, on norepinephrine overflow and antidiuresis induced by stimulation of renal nerves in anesthetized dogs

We examined the involvement of endogenous nitric oxide (NO) in noradrenergic neurotransmission and renal function in anesthetized dogs, by using NG-nitro-L-arginine (NOARG), a NO synthase inhibitor. Renal nerve stimulation (RNS) produced the frequency-dependent increase in the rate of norepinephrine secretion. The low frequency RNS (0.5-2.0 Hz) decreased urine flow and urinary excretion of sodium, without affecting renal hemodynamics. High frequency RNS (2.5-5.0 Hz) caused a more potent antidiuresis and renal vasoconstriction that resulted in reductions in renal blood flow and glomerular filtration rate. Intrarenal arterial infusion of NOARG, at a dose (10 micrograms/kg/min) which had no effect on renal hemodynamics, significantly enhanced the RNS-induced reductions of urine formation and renal vasoconstriction and increments in norepinephrine secretion rate. Qualitatively similar results were observed with a higher dose of NOARG (40 micrograms/kg/min), although this dose did decrease basal levels of renal blood flow and urine flow. Enhancement of NOARG on RNS-induced actions was abolished by the simultaneous administration of L-arginine. Endogenous NO probably has a role as inhibitory modulator of renal noradrenergic neurotransmission.

Aortic arch aneurysm repair using selective cerebral perfusion

Seventy-seven patients underwent aortic arch aneurysm repair using selective cerebral perfusion from January 1987 to August 1992. Early and long-term results and preoperative and postoperative cerebral function were evaluated. Cerebral function was assessed by the mini mental state-Himeji test and the Wechsler adult intelligence scale. Thirty-six patients had true aneurysms, and 41 had dissection. Hospital mortality for true and dissecting aneurysms was 19.4% and 7.3%, respectively. The 5-year actuarial survival rates for true and dissecting aneurysms were 59.0% and 65.3%, respectively (not significant). There were no significant differences in test scores before or after operation. Repair or replacement of the aortic arch using selective cerebral perfusion is a safe procedure with acceptable hospital mortality.

Platelets-induced stimulation of endothelin-1 production and inhibition by phosphoramidon

The effects of platelets on endothelin-1 (ET-1) production were examined by using cultured bovine pulmonary artery endothelial cells (ECs). Platelets (6 x 10(6) to 2 x 10(9) platelets/ml) prepared from rat peripheral arterial blood markedly stimulated immunoreactive (IR)-ET release from ECs into the culture medium, in a time-and platelet number-dependent manner. High-performance liquid chromatography analysis of the culture supernatant following exposure to platelets revealed one major IR-ET component corresponding to the elution position of synthetic ET-1. Northern blot analysis showed that platelets enhanced prepro ET-1 mRNA expression in the ECs. Increased IR-ET release was observed with the supernatant obtained after incubation of platelets, and this increment was significantly inhibited by transforming growth factor-beta 1 neutralizing antibody. Phosphoramidon, an ET converting enzyme inhibitor, significantly decreased the amount of IR-ET accumulating in the culture medium of ECs, incubated with or without platelets, and the decreasing effect of phosphoramidon in the presence of platelets was greater than that in their absence. A similar effectiveness of phosphoramidon was seen when transforming growth factor-beta 1 was used instead of platelets. Thus, platelets appear to stimulate the endothelial production of ET-1 in vitro, probably through a release of transforming growth factor-beta 1. We also suggest that the inhibition of ET converting enzyme by phosphoramidon is more effective in the augmented condition of ET-1 production than in the basal condition.