Identification of new epitopes recognized by human monoclonal antibodies with neutralizing and antibody-dependent cellular cytotoxicity activities specific for human T cell leukemia virus type 1

We have generated a number of EBV-transformed B cell lines producing human mAb against human T cell leukemia virus type 1 (HTLV-1) from the peripheral blood B lymphocytes obtained from patients with HTLV-1-associated myelopathy/tropical spastic paraparesis. Various synthetic peptides corresponding to antigenic regions of HTLV-1 gag and env proteins were used for the screening of antibodies in ELISA. In our study, four IgG mAb to the gag p19 amino acids 100 to 130, and 5 IgG mAb to the env p46 amino acids 175 to 199 were characterized. An immunofluorescence assay showed that all of these mAb specifically bound to the surface of HTLV-1-bearing cell lines. Among these mAb, one anti-gp46 mAb, designated KE36-11, neutralized the infectivity of HTLV-1 as determined by both the inhibition of HTLV-1-induced syncytium formation and transformation assays in vitro. An antibody-binding assay using overlapping oligopeptides revealed that KE36-11 recognized a new epitope locating between the gp46 amino acid sequence 187-193 (Ala-Pro-Pro-Leu-Leu-Pro-His). Another anti-gp46 mAb, designated KE36-7, showed antibody-dependent cellular cytotoxicity against HTLV-1-bearing cell line. KE36-7 bound strongly to the 10-mer peptide-gp46 187-196, and weakly to peptides containing the gp46 amino acid sequence 191-196 (Leu-Pro-His-Ser-Asn-Leu). These two epitopes, which are associated with HTLV-1 neutralization and antibody-dependent cellular cytotoxicity, are thus the first epitopes identified in human HTLV-1 infection. It is possible that passive immunization of humans with these two human mAb are effective on the protection of HTLV-1 infection in vivo.

Clinical evaluation of a new synthetic protease inhibitor in open heart surgery. Effect on plasma serotonin and histamine release and blood conservation

To achieve more physiologically successful cardiopulmonary bypass (CPB), the effects of a new synthetic protease inhibitor, nafamostat mesilate (FUT), were examined in open heart surgery. Thirty adult patients were divided into two groups. In Group F (GpF; n = 15), 2 mg/kg/hr of FUT was administered continuously during CPB and 0.2 mg/kg/hr before and after CPB. FUT was not given to Group C patients (GpC; n = 15), who acted as controls. Serotonin and histamine levels in plasma, platelet counts, platelet adhesive function levels, and alpha 2 plasmin inhibitor-plasmin complexes (PIC) were serially measured. The serotonin level in GpF was significantly lower at 5 min of CPB than in GpC. Histamine levels in GpC decreased remarkably after starting CPB, then later recovered; by contrast, they did not decrease in GpF during CPB. At 1 hr after CPB, platelet counts were higher (p < 0.01) in GpF (54 +/- 8%) than in GpC (41 +/- 10%), and platelet adhesion was lower (p < 0.01) in GpF (7 +/- 7%) than in GpC (34 +/- 13%). The PIC was significantly less in GpF than in GpC throughout the surgery. Blood loss in GpF was significantly reduced compared with that in GpC. In conclusion, FUT attenuated chemical mediator reactions, such as plasma serotonin and histamine, and also reduced blood loss by preserving platelets and inhibiting fibrinolysis during CPB.

Simple and efficient chemosensitivity assay for human primary tumor-cells using contact-sensitive microtiter plates

A simple and efficient chemosensitivity assay for human primary tumors has been developed using 96-well microtiter plates covered totally with lethally irradiated 3T3 monolayers termed cell mats, on which the proliferation of normal human fibroblasts is preferentially inhibited. Two days after the inoculation of tumor cells into the microtiter cell mat plates, the cells were treated with various anticancer drugs, and the cell numbers were assessed by radioactivity using a 96-well automatic scintillation counter after subsequent radiolabeling with H-3-deoxyuridine for 24h. In this manner, complete dose response curves of many anticancer drugs were available from one plate within 5 days. Drugs tested in triplicate were adriamycin, mitomycin C, cisplatin, etoposide, and 5-fluorouracil at 0.01, 0.1, and Ix the peak tolerated drug concentrations in serum. Clinically, of the 39 primary tumor specimens of different types received, 4 were contaminated. The remaining 35 samples were successfully cultured, with 5 cultures being abandoned due to an insufficient cpm. As a result, cell survival curves were obtained from 30 (77%) specimens. This high evaluable rate might be due to the feeder effect brought by cell mats. Although optimization of the assay system has yet to be determined, the ability to have multiple drug sensitivity per plate with short-term duration would make this system an efficient assay for chemosensitivity test of human primary tumor cells.

Evaluation of the biocompatibility of a new method for heparin coating of a cardiopulmonary bypass circuit

The biocompatibility of the Terumo (Terumo Corporation, Tokyo, Japan) covalent heparin coating method in a cardiopulmonary bypass (CPB) circuit was evaluated in ex vivo and in vivo experiments. In the ex vivo experiment, fresh human heparinized blood primed both a miniature heparin coated circuit (HCC) and the identical noncoated circuit (NCC), and was circulated simultaneously for 2 hr (n = 6). In the in vivo experiment, 10 rabbits underwent 2 hr of CPB under systemic heparinization (ACT > 400 sec) with HCC (n = 5) and with NCC (n = 5). In the ex vivo study, thrombin/anti-thrombin III complex, thromboglobulin, platelet factor IV, granulocyte elastase, and C3a were significantly lower in the HCC than in the NCC at 60 and 120 min of circulation (p < 0.05). In the in vivo study, platelet counts (percent of value at 10 min of CPB) were significantly higher in the HCC than NCC (HCC:NCC 87 +/- 10:71 +/- 12 at 60 min, 81 +/- 17:56 +/- 16 at 120 min). Scanning electron microscopic examination of the circuits showed less significant adhesion and pseudopod formation of platelets in the HCC than NCC in both ex vivo and in vivo situations. These results demonstrate that this heparin coated CPB circuit provides superior biocompatibility compared with a noncoated circuit by reducing the activation of the coagulation cascade, platelets, leukocytes, and complement.

Effects of endurance training under hyperoxia on serum and tissue lipid levels in rats

Effects of 6 weeks endurance training (5 days per week) under hyperoxia (60% O2 plus 40% N2) on serum and tissue lipid levels were investigated in male rats. Rats were divided into 4 groups: normoxia-control (NC), hyperoxia-control (HC), normoxia-training (NT), and hyperoxia-training (HT). NT and HT groups were run on a treadmill in a chamber at 20 m per min with a 6 degree gradient for 30 min. The chamber was perfused with hyperoxic gas. After training under hyperoxia, high density lipoprotein cholesterol (HDL-C) was higher (p less than 0.01) than in the normoxic condition, but there were no changes in serum lipids and glucose, or liver and aorta cholesterol. Skeletal muscle TG and liver glycogen in hyperoxic condition tended to show the higher values. Basal lipolysis of adipose tissue was increased (p less than 0.05) by hyperoxia, and decreased (p less than 0.01) by training, but there was no change of norepinephrine induced lipolysis in any group. The results suggest that endurance training or resting under hyperoxia induces increased HDL-C or lipolytic activity of adipose tissue. These effects might be caused by greater fat oxidation during exercising or resting under hyperoxia.

[Sequential coronary artery bypass using gastroepiploic artery]

We carried out sequential coronary bypass grafting using the gastroepiploic artery (GEA) as an in situ graft in seven patients. Four patients had sequential graft from the right coronary to the circumflex. Three patients were anastomosed to two or three peripheral branches of the right coronary artery. There were no early deaths. Postoperative angiograms revealed that the patency rate was 92.3% (12/13 anastomoses). Sequential GEA grafting is available to anastomose the peripheral branches of the right coronary and the circumflex where the in situ internal thoracic artery is difficult to access. Therefore, this procedure will be indicated for multiple coronary artery bypass grafting.

[Assessment of Blalock-Taussig shunts in children with complex cardiac anomalies associated with reduced pulmonary blood flow and total anomalous pulmonary venous drainage]

Eleven patients with syndromes of asplenia and polysplenia associated with total anomalous pulmonary venous drainage (TAPVD) were underwent Blalock-Taussig (B-T) shunt operation for reduction of pulmonary blood flow. The age of patients at operation were 6 days to 5 years (average 19.5 +/- 18.7 month). There were seven patients in supracardiac type and four in cardiac type of TAPVD. All patients didn't present obstruction to pulmonary venous return (PVO) before B-T shunt operation. There were one early (9%) and two late deaths (20%) after surgery. Although the hospital death was related to perioperative errors. Two late deaths were not due to the PVO. One of infants had moderately pulmonary congestion and cardiac failure after shunt procedure. Two patients were measured pressure gradient (3 to 4 mmHg) between common pulmonary vein to atrium chamber before shunt procedure. Repeated catheterization revealed that 6 of them could be measured pressure gradient, 3 to 7 mmHg, and no patients had clinical sign of the PVO. Our results demonstrated that B-T shunt operation could be satisfactory for syndromes of asplenia and polysplenia associated with reduced pulmonary blood flow and TAPVD.

Myocardial energy metabolism in asphyxiated canine hearts preserved for 24 hours

Myocardial energy metabolism in asphyxiated cadaver hearts preserved in UW solution (UWS; group 1, n = 6) or modified Collins' solution (MCS; group 2, n = 6) was compared with that in cardioplegic arrested hearts immersed in ice-cold MCS with (group 3, n = 6) or without myoprotective drugs (group 4, n = 5). All hearts were stored for 24 hr. The hearts in groups 1 and 2 were pretreated with prostacyclin, verapamil, and propranolol; asphyxiated for 10 min, reversed by coronary perfusion with warm blood cardioplegia (WBCP); perfused with ice-cold crystalloid cardioplegia for 2 hr; excised and immersed in cold storage solution for 22 hr; and perfused again with WBCP before reperfusion. ATP contents were measured in biopsy specimens by HPLC. Myocardial ATP level decreased significantly from 23.7 +/- 1.7 to 15.9 +/- 2.5 mumol/g dry wt. (P less than 0.0001) by asphyxia, but recovered to within normal limits by WBCP in group 1. The ATP level again decreased to 15.8 +/- 2.4 mumol/g dry wt. during 24-hr storage, but finally rose to 22.4 +/- 3.5 mumol/g dry wt. by terminal WBCP. The ATP metabolism in group 2 was similar to that in group 1. The ATP content in group 4 was significantly lower than that in other groups (P less than 0.01) after 24-hr preservation. The study shows that damage to cadaver hearts can be reversed and the hearts maintained satisfactorily viable for 24 hr.

[An unusual case of annular constrictive pericarditis--a "framed heart"]

We presented a 62-year-old female with constrictive pericarditis of an unusual anatomy. A calcified constrictive band, 2-3 cm wide, ran parallel to the frontal plane, coursing circularly along the anterior aspect of the great arteries, right atrium, diaphragmatic surface of the right ventricle, posterolateral aspect of the left ventricle and back to the great arteries. The course of the constrictive band was circular but completely different from that of typical annular constrictive pericarditis in which a constrictive band runs along the atrioventricular groove. Hemodynamic consequences of our patient was rather non-specific impairment of ventricular filling than functional valvular stenoses due to external compression characteristic for the typical annular constrictive pericarditis. Effective surgical relief of the constriction was accomplished under cardiopulmonary bypass and cardioplegic cardiac arrest.

The binding of basic fibroblast growth factor to ischaemic neurons in the rat

Transient occlusion of the right middle cerebral artery for 15 min produced a small ischaemic lesion in the dorsal portion of the right striatum in rats as seen on days 3, 7 and 14 post-operatively. The lesions consisted mainly of reactive astrocytes and 'ischaemic neuron's with chromatin-condensed (pyknotic) nuclei and homogenously eosinophilic cytoplasm. The incubation of tissue sections with basic fibroblast growth factor (bFGF) followed by anti-bFGF, or with biotinylated bFGF without anti-bFGF, labelled virtually all ischaemic neurons, indicating that bFGF had bound to the latter. The pretreatment of sections with heparitinase prevented the binding of bFGF to these cells, suggesting that the chemical substrate for the bFGF binding was heparan sulphate. In light of the findings that many normal-looking neurons were observed in the corresponding portion of the right striatum in most rats on post-operative days 28 and 90, the appearance of bFGF-binding sites in ischaemic neurons may contribute to the repair process of injured neurons.

[Single dose toxicity studies of suplatast tosilate (IPD-1151T)]

Single dose toxicity studies of suplatast tosilate (IPD-1151T) were carried out in mice, rats and dogs of both sexes. The results were as follows: 1. The LD50 values of IPD-1151T were as follows: Mice, 12,500 (both sexes) mg/kg or more in oral route (maximum dose for technical manner); Mice 81 (male) and 96 (female) mg/kg in intravenous route; Rats, 10,000 (both sexes) mg/kg or more in oral route (maximum dose for technical manner); Rats, 96 (male) and 93 (female) mg/kg in intravenous route; Dogs, 2,124 (male) and 2,660 (female) mg/kg in oral route. On the LD50 values, no sexual difference was apparent in all species, but the species difference was noted between the rodent and dog. LD50 values of dog were lower level than those of rodent. 2. As toxic signs, mucous diarrhea with specific smell was noted in orally administered rodent. In addition, rats showed soiled fur in the perianal. In intravenous route, the rodent showed dyspnea, tonic convulsion and lateral position and deaths occurred within 10 min in mice and within 30 min in rats after administration. Dog showed toxic signs similar to those in rodents and deaths occurred within 3 hours. 3. In pathological examinations, dead mice and dogs administered orally showed lung congestion, liver fading or slight hemorrhage in the endo-and/or exocardium. Dead rodent administered intravenously showed only slight hemorrhage and congestion in the lung. Alive mice, rats and dogs showed no remarkable changes. 4. The main cause of deaths seemed to be respiratory disturbance in all species.

[A thirteen-week oral repeated dose toxicity study of suplatast tosilate (IPD-1151T) in rats]

A 13-week oral repeated dose toxicity study of Suplatast tosilate (IPD-1151T), a new anti-allergic agent, as well as a 5-week recovery study were carried out at dose levels of 0 (control), 200, 600, 1800 and 5400 mg/kg/day using male and female rats. The results were as follows: 1. In general conditions, salivation were observed in some rats of both sexes given 1800 mg/kg/day. Both sexes given 5400 mg/kg/day disclosed salivation and soft stool and then died after showing ataxic gait, hyperesthesia and convulsion of legs. 2. Inhibition of body weight gain in both sexes given 5400 mg/kg/day were observed from the early stage of the treatment period. 3. The food consumption was decreased from about 3-week and the water consumption was increased from the initiation of study to about 3-week in both sexes given 5400 mg/kg/day. However, both of them were remarkably decreased prior to death. 4. Fecal examination for occult blood showed an increasing tendency in the incidence of positive findings in both sexes given 1800 mg/kg/day. 5. Hematological examination showed slight decreases in erythrocytic parameters in both sexes given 1800 mg/kg/day. In both sexes given 5400 mg/kg/day hemoconcentration was observed, some animals showing decreases in leucocyte and lymphocyte counts and lymphocyte percentage. 6. Biochemical examination showed increases in total and free cholesterol levels in males given 600 mg/kg/day or more, an increased cholinesterase and decreased levels of triglyceride and cholesterol ester ratio in males given 1800 mg/kg/day. An increase in LDH was observed in both sexes given 5400 mg/kg/day and half of these animals also showed increases in GOT and Urea N. 7. The absolute weights of the pituitary, brain, thymus, heart, lungs and kidneys were increased. However, no histopathological lesion was observed in these organs. As treatment-related histological changes, atrophy in the thymus and spleen, dilation in digestive tracts, neuronal necrosis and necrotic foci in the central nervous system, necrosis of lymphocytes in the lymphoid organs and a decrease in bone marrow cell were observed in both sexes given 5400 mg/kg/day. 8. After a 5-week recovery period, above-mentioned changes had disappeared. 9. From the above results, the non-effective dose level was estimated to be 200 mg/kg/day in males and 600 mg/kg/day in females, and toxic dose level 1800-5400 mg/kg/day in both sexes.

Magnetic resonance imaging of a malignant transformation of an intracranial cellular blue nevus. A case report

As a follow-up to a case previously reported, a rare case of malignant transformation of cellular blue nevus (CBN) in the central nervous system preoperatively diagnosed by magnetic resonance imaging (MRI) is reported. On MRI, the malignant portion of the nevus was slightly hyperintense on both T1- and T2-weighted images. In contrast, the benign portion with a great deal of melanin was hyperintense on T1-weighted image and hypointense on T2-weighted image. MRI was useful and indispensable for detecting the malignant transformation of CBN.

[A case of ectopic ureter with renal dysplasia simulating epididymal structure]

A 30-year-old man was admitted to our hospital suffering from fever and left scrotal swelling. Physical examination revealed an enlarged left epididymis, suggesting acute epididymitis. Intravenous pyelography showed non-functioning left kidney. On cystoscopy, the left ureter orifice did not open in the bladder, and it opened in the posterior urethra. An ureteral catheter was passed through this orifice to about 5 cm length and retrograde injection of contrast material demonstrated a dilated left ureter. CT also confirmed a dilated left ureter behind the bladder and the left kidney was not found. Left nephroureterectomy was performed. Microscopically, normal renal tissue was not recognized, and the lesion comprised a number of ducts covered with tall columnar epithelium having stereocilia and ducts resembling the thyroid gland. The former ducts resembled the ducts of epididymis. The pathological diagnosis was total dysplasia.

[Establishment and characterization of human ovarian fibrosarcoma cell line and its sensitivity to anticancer agents]

We succeeded in establishing a cell line (KEN-3) for subculture from a fibrosarcoma which originated in the ovary in a girl aged 17 years. Its characteristics and sensitivity to anticancer agents are reported in this paper. 1. Characteristics of established cell line. Lined cells consist of multinucleated giant cells mixed among many spindle-shaped cells. They grow in small colonies and have none of the pavement-like arrangement characteristic of epithelial tumor cells. The number of chromosomes ranged from 45 to 128 (mode: pseudo-triploidy region, 65). The doubling time, cellular density and plating efficiency were 76.9 hours, 5.4 x 10(5)/cm2 and 30.2%, respectively. Concerning tumor markers, CEA and sialyl SSEA-1 were only produced in small quantities. Subculture was possible subcutaneously in the nude mouse with no capacity for the production of ascites. 2. Susceptibility to anticancer agents and GP170 expression. The in vitro susceptibility to about 12 types of anticancer agents was investigated with the MTT assay. IC50/PPC was shown to be less than 1 for Adriamycin only. The sensitivity to CDDP (IC50/PPC: 4.8) was low, and no sensitivity was observed at all to DTIC, which is used frequently for mesenchymal tumors. GP170 (mdr-1 products) was positive in established cells in immunohistochemical stain.

Chronopharmacokinetics and chronotoxicity of lithium in mice eating normal and low-sodium diets

The temporal aspects of the pharmacokinetics and toxicity of lithium were studied in mice eating normal and low-sodium diets. ICR male mice, housed under a light:dark (LD; 12:12) cycle, were injected with variable doses of lithium chloride i.p. A circadian rhythm was found in lithium clearance after a single administration in mice eating the normal diet showed the maximum value in the early dark phase and the minimum in the early light phase. The repeated administration of lithium did not affect the rhythm of the pharmacokinetics of the drug under the LD cycle. Although the low-sodium diet significantly decreased the lithium clearance, it did not influence the rhythm of the clearance. Higher toxicity was demonstrated in mice injected with the drug at the time of day with lower lithium clearance in the single-dose study but not in the repeated-doses study, regardless of the diet conditions. The low-sodium diet increased the acute and chronic toxicity of lithium. The results indicate that there is a circadian rhythm of acute toxicity and clearance of lithium after a single dose or repeated administration of the drug in mice eating normal and low-sodium diets and that the low-sodium diet increases lithium toxicity by reducing the clearance of the drug without influencing the rhythm characteristics.

Localization of protein kinase C in human skeletal muscle

The immunolocalization of protein kinase C (PKC) isozymes alpha, beta I and beta II, was investigated in human skeletal muscle. All three isozymes were present on the muscle fiber surface membrane and within the muscle fibers. The alpha-isozyme was most clearly delineated on the surface membrane of the muscle fiber and on small blood vessels in the connective tissue. The axons of myelinated intramuscular nerves stained intensely for the beta I isozyme, whereas the endoneurial connective tissue reacted more strongly for the alpha- and beta II-isozymes. PKC isozymes may regulate intracellular signal transduction in human skeletal muscle, as in the other tissues, but their exact role in muscle remains unknown.

Transaortic patch angioplasty for left coronary ostial stenosis in a patient with Takayasu's aortitis

A 35-year-old woman who had left coronary ostial stenosis and aortic valve regurgitation due to Takayasu's aortitis underwent transaortic patch enlargement of the stenosed left coronary ostium in combination with aortic valve replacement. This technique may be suitable and recommendable as an alternative to aortocoronary bypass grafting or endarterectomy for coronary ostial stenosis in Takayasu's aortitis.

Microcalorimetric measurements of heat production in isolated rat brown adipocytes

Heat production, oxygen consumption, and lipolysis in isolated interscapular brown adipocytes from the rat were investigated. Epinephrine, norepinephrine, and isoproterenol increased heat production in a concentration-dependent manner, showing, about 6-, 4-, and 5-fold higher effects than controls, respectively. The concentration of isoproterenol for threshold heat production and glycerol release were 10(-10) M and 10(-9) M, respectively. The fact that 10(-9) M isoproterenol increased heat production by about 3-fold while glycerol release had no effect at all indicates that calorimetry is more appropriate for investigation of brown adipocytes. At least the method is more sensitive than that of measuring glycerol release.

[Surgical repair of infarct-related ventricular septal perforation using Teflon felt patch]

Eight patients with infarct-related ventricular septal perforation underwent surgical repair using Teflon felt patch. The overall early operative mortality rate was 12% (1/8). One of three patients (33%) with cardiogenic shock preoperatively, one of five patients (20%) operated within 7 days after the onset of infarction died within 30 days after operation. A patient with inferior infarction died early after operation. In 5 of 8 patients (63%), IABP was removed within 24 hours after operation. A patient died due to the recurrence of gastric cancer in late postoperative phase. None of patients was found to have a recurrence of the ventricular septal perforation after the operation. Five of 6 patients (83%) surviving the operation are in NYHA class I or II.

Cardiac function and myocardial performance of 24-hour-preserved asphyxiated canine hearts

A method of 24-hour storage of asphyxiated canine hearts for orthotopic cardiac transplantation was studied to expand the geographical size of the donor pool. Left ventricular function of asphyxiated hearts preserved for 24 hours (group 1, n = 8) was compared with that of hearts donated on-site (group 2, n = 5). Group 1 donors were pretreated with verapamil hydrochloride, propranolol hydrochloride, and prostacyclin. The donor hearts were perfused with warm blood cardioplegia in situ after 10 minutes of asphyxiation and then perfused with cold crystalloid cardioplegia for 2 hours. The hearts were excised and stored in ice-cold University of Wisconsin solution for 22 hours. At orthotopic transplantation, coronary perfusion with warm blood cardioplegia was performed before the graft aorta was unclamped. Conventional cardiac variables (eg, cardiac output and maximum rate of rise of left ventricular pressure), myocardial performance, and diastolic compliance of grafted hearts were assessed 1 hour after weaning from bypass. All recipients in both groups were easily weaned from cardiopulmonary bypass without inotropic agents, and there were no significant differences in cardiac variables between the two groups. These results strongly suggest that cadaver hearts can be preserved for 24 hours with satisfactory cardiac function.

Determination of optimal perfusion flow rate for deep hypothermic cardiopulmonary bypass in the adult based on distributions of blood flow and oxygen consumption

To determine the optimal perfusion flow in deep hypothermic cardiopulmonary bypass at 20 degrees C in human beings, we studied the relationship of perfusion flow to the whole body and to regional oxygen consumption. In adult patients (n = 11, average age 54 years) with valvular or coronary heart disease, the distributions of perfusion flow rate and oxygen consumption were analyzed by dividing into the superior and inferior vena caval areas. Measurements (n = 39) were made at various perfusion flow rates (perfusion flow rate in the superior vena caval area plus that in the inferior vena caval area equals whole-body perfusion flow rate: 0.4 to 2.2 L/min/m2) in a setting of average hemoglobin levels of 8.1 gm/dl. Between whole-body perfusion flow rate and oxygen consumption (total oxygen consumption equals superior plus inferior vena caval oxygen consumption), there was a hyperbolic correlation (r = 0.73; p less than 0.001; asymptote = 29.0 ml/min/m2). A positive linear correlation was found between whole-body perfusion flow rate and inferior vena caval oxygen consumption (r = 0.75; p less than 0.001), whereas no significant relation was seen between whole-body perfusion flow rate and superior vena caval oxygen consumption. For distributional changes in inferior vena caval perfusion flow rate/whole body perfusion flow rate and inferior vena caval oxygen consumption/whole body oxygen consumption, the broken-line regression analysis showed respective critical points where both parameters started to drop when whole-body perfusion flow rate was gradually reduced: 1.2 L/min/m2 for inferior vena caval perfusion flow rate/whole-body perfusion flow rate and 0.8 L/min/m2 for inferior vena caval oxygen consumption/whole-body oxygen consumption. The results indicate that (1) the oxygen consumption to the superior vena caval area was maintained independent of the perfusion in a relatively wide range in contrast to that for the inferior vena caval area and (2) when the redistribution of oxygen consumption is considered as undesirable under low-flow perfusion, the optimal perfusion flow for 20 degrees C deep hypothermic cardiopulmonary bypass appeared to be 0.8 L/min/m2.