Scintigraphic detection of xenografted renal tumor by anti-renal cancer monoclonal antibody radiolabeled with technetium-99m

Accumulation in the tumor of the RCS-1 monoclonal antibody, which recognizes the cell surface antigen of renal cancer cells was examined. The antibody purified by affinity chromatography (protein-A column) and gel fractionation was labeled with technetium-99m (99mTc) by a direct method. High labeling efficiency (> 98%) could be routinely obtained. However, the 99mTc labeling of the antibody did not reduce the reactivity of the RCS-1 antibody. The labeled antibody was injected into nude mice transplanted with human renal and gastric tumors, and the accumulation of the antibody in each tumor and various tissues was compared at 48 hours after injection. The highest accumulation of radiolabeled RCS-1 antibody was observed in the AM-RC-3 renal tumors; at 8.0% of the injected dose per gram and a tumor-to-blood ratio of 1.05, respectively. However, the radiolabeled RCS-1, did not show specific accumulation in the gastric tumor nor in any tissues tested. The xenografted tumor, AM-RC-3 was successfully visualized with the radiolabeled RCS-1 antibody by scintigraphy.

[The comparison of hypnotic potency of nitrous oxide with that of sevoflurane: evaluation by the middle latency auditory evoked response]

In 10 consented patients (ASA I-II) we quantitated the hypnotic potencies of 0.7 MAC nitrous oxide and 0.7 MAC sevoflurane by measuring auditory evoked response (AER), and compared the hypnotic potency of nitrous oxide with that of sevoflurane at the same MAC. In each patient, measurements of AER waves were performed in the following three stages, 0.7 MAC nitrous oxide, 0.7 MAC sevoflurane and 0.7 MAC nitrous oxide after induction of anesthesia. Analysis of variance was used to compare the hypnotic potencies between two inhaled anesthetics. Pa and Nb latencies with sevoflurane were longer than those with nitrous oxide, and Pa and Nb amplitudes with sevoflurane were greater than those with nitrous oxide. However, we found that there were no statistical significances in our results. In conclusion, nitrous oxide exerts as much hypnotic effect as sevoflurane.

[Two cases of priapism cured by transcatheter embolization of internal pudendal arteries]

We report here two cases of priapism. One of these cases was suspected to be drug induced and high and low flow mixed type. The patient had taken the drugs, alpha-blocker for hypertension and dysuria by BPH for a long time. He was treated by a caveno-glandular shunt. After surgery, detumescence was obtained for some time, but erection appeared again soon. Transcatheter embolization of the internal pudendal arteries was then performed, and detumescence became permanent. The other case was an idiopathic and high flow type. Detumescence was achieved soon by transcatheter embolization of the internal pudendal arteries only, then he experienced morning erection imperfectly on the 9th day after this treatment. The management of priapism as reported to date is also reviewed.

An approach to cerebral vasodilatory capacity in unilateral and bilateral cerebrovascular diseases using radiolabeled human serum albumin

The acute cerebrovascular response to acetazolamide was assessed using a blood pool agent and planar dynamic imaging to evaluate cerebral vasodilatory capacity. Ten normal subjects and 12 patients with unilateral or bilateral cerebrovascular disease were studied. After the injection of radiolabeled human serum albumin, dynamic imaging of the anterior view of the head was started. Ten minutes later, 1000 mg of acetazolamide was infused. The dilatation index (the percent increase in activity at the peak response) was obtained for each cerebral hemisphere. The mean dilatation index in normal subjects was 17.1 +/- 3.2% (N = 20). The value was significantly lower in patients with multiple infarcts (7.7 +/- 1.1%, N = 8, P < 0.001), and below the normal range in two involved hemispheres of five patients with unilateral occlusive carotid artery disease and in three hemispheres of three patients with moyamoya disease. It was suggested that this simple method may be useful in assessing cerebral vasodilatory capacity in both unilateral and bilateral diseases.

[The effect of iontophoresis with several Ca channel blockers for PHN patients]

We performed iontophoresis with Ca channel blockers for healthy adult volunteers. In this clinical study, we used iontophoresis with Ca channel blockers. Ten out patients with PHN treated at our pain clinic were treated with iontophoresis. They were randomly assigned to one of the following four treatments: (1) 5 ml of 4% lidocaine HCl, (2) 2 mg of nicardipine HCl + 5 ml of distilled water, (3) 2 mg of verapamil HCl + 5 ml of distilled water, and (4) 2 mg of diltiazem HCl + 5 ml distilled water. Iontophoresis was performed using the above four drugs on the positive pole. Using a VAS, each patient was evaluated concerning the analgesic effect. The pain before treatment (10 points) was used as the base line. Compared with the scores before treatment, VAS scores decreased significantly after iontophoresis in all four groups. In the lidocaine group, a significant decrease in VAS scores occurred immediately after iontophoresis and lasted up to 24 hours, reaching the nadir at 2 hours. In the nicardipine group, the decrease occurred immediately after iontophoresis and lasted up to one day, reaching the nadir at four hours. In the verapamil group, the decrease started 1 hour after iontophoresis and lasted up to 48 hours, reaching the nadir at 8 hours. In diltiazem group, the decrease started 1 hour after iontophoresis and lasted up to 48 hours, reaching the nadir at 4 hours. Iontophoresis with Ca channel blockers produced a prolonged analgesic effect in PHN patients. Previously we had observed the same effect in adult volunteers. Therefore, we believe that this therapy will be clinically useful.

Measurement of cerebral blood flow with two-dimensional cine phase-contrast mR imaging: evaluation of normal subjects and patients with vertigo

PURPOSE

The purpose of this study was to determine whether or not the vertebral flow of patients with vertigo and normal brain magnetic resonance (MR) images was decreased in comparison with normal controls.

MATERIALS AND METHODS

Cerebral blood flow (CBF) was quantitatively measured by a two-dimensional phase contrast cine MR imaging technique in 24 normal controls (mean age, 38.6 years; range, 12-70) and 23 patients (mean age, 53.7 years; range, 19-76) with a 1.5 Tesla MR imaging unit.

RESULTS

Inter- and intraobserver variation in blood flow measurements was small (r = 0.970, standard error of the estimate [SEE] = 2.9 ml, n = 80; r = 0.963, SEE = 4.6 ml, n = 40, respectively). In the normal group, mean summed vertebral flow (171 ml/min, SD = 40.6) was significantly less than mean summed carotid flow (523 ml/min, SD = 111). Right vertebral flow (80.2 ml/min, SD = 30.5) was less than left vertebral flow (91.2 ml/min, SD = 38.2), but the difference was not statistically significant (p < 0.05). In the 23 patients, although the summed vertebral flows of two patients (63.3, 88.8 ml/min) were significantly less than that of the normal group, mean summed vertebral flow (165 ml/min, SD = 59.1) showed no significant difference from that of the normal group (p < 0.05).

CONCLUSIONS

In this study, the majority of patients had normal CBF. This method is clinically useful for estimating CBF.

Semiquantitative analysis by scanning electron microscopy of cochlear hair cell damage by ototoxic drugs

The ototoxicity of cisplatin and carboplatin in the organ of Corti of the guinea pig was evaluated semiquantitatively. Damage of the stereocilia of outer hair cells (OHCs) observed by scanning electron microscopy (SEM) was classified into normal, grade 1 (10-50% loss of stereocilia), grade 2 (less than 50% remaining stereocilia), or grade 3 (missing stereocilia). The OHCs observed by light microscopy (LM) were classified as remaining or missing cells. Fifty OHCs of each row in the middle part of each turn of the cochlea were counted (a total of 150 cells per turn). Guinea pigs were administered 5 mg/kg of cisplatin or 50 mg/kg of carboplatin intraperitoneally for three consecutive days. In groups 1 and 2, in which both cochlea were fixed in 2.5% glutaraldehyde and 1% osmium tetroxide (OsO4) and observed by SEM, the percentages of damage of the OHC stereocilia were similar in each cochlear turn bilaterally. In group 3, the right cochleae were fixed in OsO4 and observed by phase contrast microscopy as surface preparations. Left cochleae were submitted for SEM observation. Missing and grade 3 cells were observed at similar percentages in each row of each turn. In group 4, succinate dehydrogenase staining was performed in the right cochleae and observed by LM. The degree of damage in the right cochleae was compared with that of the left cochleae which was observed by SEM. On average, the mean numbers of missing cells and cells showing grade 3 damage were similar in each row of each turn. From these similarities of evaluation of ototoxicity at LM and SEM levels, it was concluded that semiquantitative analysis by SEM only is appropriate for the assessment of ototoxicity.

[The efficacy of midazolam-famotidine suppository for premedication in children]

We evaluated the efficacy of midazolam-famotidine suppository (M-F suppository) for premedication in children. After obtaining informed parental consent, we studied children aged 5m-7y, ASA I status, scheduled for minor elective surgery. The suppository group (n = 26) was given suppository of both midazolam 0.5 mg.kg-1 and famotidine 2 mg.kg-1, and the intramuscular injection group (n = 19) was given hydroxyzine 1 mg.kg-1. In the suppository group, gastric pH (3.90 +/- 0.34) was significantly higher, and gastric volume (1.88 +/- 0.54 ml) was significantly less than in the intramuscular injection group (1.82 +/- 0.15, 8.42 +/- 1.76 ml). The M-F suppository may offer similar sedative effect as an intramuscular injection of hydroxyzine. We concluded that the M-F suppository is an effective premedicant for pediatric patients.

[MR diagnosis for metastasis or non-metastasis of mediastinal and hilar lymph nodes in cases of primary lung cancer: detectability, signal intensity, and MR-pathologic correlation]

The detectability and signal intensity on MR imaging of mediastinal and hilar lymph nodes were studied in cases of lung cancer. Additionally, short inversion time inversion recovery (STIR) images and pathologic findings were compared. In the detection of resected metastatic mediastinal and hilar lymph nodes (n = 146), the STIR image (82%) was superior to the T1-weighted image (71%) and the T2-weighted image (60%). On STIR imaging, 212 (60%) of 412 resected non-metastatic mediastinal nodes and 38 (33%) of 116 resected non-metastatic hilar lymph nodes were detected. Characteristics of signal intensities of metastatic nodes were mainly low on T1-weighted images, high on T2-weighted images, and very high on STIR images. The rate of these characteristics of signal intensity of metastatic nodes was 59%. However, the rate of very high signal intensity of metastatic nodes on STIR imaging was 81%. Pathologically, lymph nodes with high or very high signal intensities on STIR images were metastatic, reactive and hyperplastic, or non-metastatic. Lymph nodes with slightly high signal intensity or high intensity with a low focus on STIR images were anthracotic, anthrasilicotic, caseous necrotic, calcified, or fibrotic. Thus, when the signal intensity of a lymph node was decreased on the STIR image, there was no definite evidence of metastasis excluding micro-metastasis or coagulation necrosis of a metastatic tumor. We conclude that the signal characteristics on STIR imaging are useful for distinguishing between macro-metastatic and non-metastatic lymph nodes when enlarged nodes are detected by various other types of medical imaging.

Background correction in estimating initial renal uptake. Comparison between Tc-99m MAG3 and Tc-99m DTPA

A gamma camera method with no blood sampling assesses differential renal function based on initial renal uptake, and requires background correction. The effect of background correction on estimates of initial renal uptake was compared on renograms using Tc-99m MAG3 and Tc-99m DTPA renographies in 14 patients. Renal counts for 2-3 minutes were obtained using three sets of regions of interest (ROIs): rectangular renal and subrenal background ROIs, rectangular renal and perirenal background ROIs, and hand-drawn renal and subrenal background ROIs. Correlations between estimates of initial renal uptake by the three methods were higher for Tc-99m MAG3 renography than for Tc-99m DTPA imaging, suggesting higher reproducibility in evaluating differential renal function using Tc-99m MAG3 renography and a gamma camera method. Although the ratio of counts in the suprarenal area to those in the subrenal area was significantly higher for the right side in the Tc-99m MAG3 study, probably because of hepatic activity, the relative uptake in the right kidney for Tc-99m MAG3 did not differ from that for Tc-99m DTPA. Initial uptake of Tc-99m MAG3 was well correlated with, and about threefold that, of Tc-99m DTPA. It was suggested that initial renal uptake of Tc-99m MAG3 may be an alternative to that of Tc-99m DTPA, with less dependence on background correction in evaluating differential renal function.

[Intra-ocular pressure changes during laparoscopic cholecystectomy]

Intra-ocular pressure (IOP) was measured during laparoscopic cholecystectomy (n = 20) under continuous epidural block and nitrous oxide-oxygen anesthesia. There was a slight but significant increase in IOP and peak airway pressure when the abdominal CO2 insuffration was started, and the IOP recovered to the preoperative level after the postural change to the head-up position. It was not associated with any significant change in mean arterial pressure and end-tidal CO2. In one ocular hypertension case undergoing laparoscopic chorecystectomy and appendectomy, however, there was profound increase in IOP during abdominal CO2 insuffration with head down position. We speculate that it was due to the effect of increased CVP with abdominal CO2 insuffration and postural change on the IOP. Thus the laparoscopic operation with head-down position should be avoided in patients with ocular hypertension.

Abnormal sympathetic innervation of the heart in a patient with myotonic dystrophy detected with I-123 MIBG cardiac SPECT

Iodine-123 MIBG is a norepinephrine analog which can be used to image the sympathetic innervation of the heart. The authors report a patient with myotonic dystrophy whose I-123 MIBG SPECT revealed accelerated washout of I-123 MIBG from infero-posterior and a part of lateral wall, although Tl-201 SPECT showed no abnormal finding. The authors conclude that I-123 MIBG can be more sensitive in detecting the cardiac abnormality than Tl-201 SPECT in this disease.

[Measurement of cerebral blood flow in normal subjects by phase contrast MR imaging]

Global cerebral blood flow (CBF) was quantitatively measured with a two-dimensional phase contrast cine magnetic resonance (MR) imaging technique in 24 normal subjects (mean age, 38.6 years; range, 12-70 years). Cine transverse images of the upper cervical region (32 phases/cardiac cycle) were acquired with a 1.5 Tesla MR imaging unit. In five subjects, measurement of CBF was performed before and after intravenous administration of acetazolamide (DIAMOX, 15 mg/kg). Inter- and intraobserver variations in flow volume measurement were small (r = 0.970, standard error of the estimate (SEE) = 2.9 ml/min, n = 80; r = 0.963, SEE = 4.6 ml/min, n = 40, respectively). In measuring flow velocity, they were inferior to those of flow volume measurement. On a visually determined setting of region of interest (ROI), reproducibly of the measurement of flow velocity was not satisfactory in this study. Thus only the results of flow volume measurement are presented. Mean summed vertebral flow volume (171 ml/min, SD = 40.6) was significantly less than mean summed internal carotid flow volume (523 ml/min, SD = 111). Total blood flow volume showed a significant decline with age (r = 0.45, p < 0.05). The mean proportions of carotid and vertebral flow volume to total flow volume were 75.3% and 24.7%, respectively, and showed no significant change with age. The left-to-right ratio of vertebral flow volume (1.39) was significantly higher than that of internal carotid flow volume (0.99, r = 0.05). After DIAMOX i.v., the mean rate of increase in total flow volume was 157%. Mean rates of increase in carotid and vertebral flow volume were 154% and 166%, respectively, which were not significantly different. In conclusion, this method is useful for estimating carotid and vertebral flow volume.

Glycine 85 of the trp-repressor of E. coli is important in forming the hydrophobic tryptophan binding pocket: experimental and computational approaches

Experimental and computational analyses were performed on the corepressor (L-tryptophan) binding site of the trp-repressor of Escherichia coli to investigate the ligand-protein interactions. Gly85, one of the residues forming the hydrophobic pocket of the binding site, was systematically replaced with Ala, Val, Leu and Trp by cassette mutagenesis. Biochemical characterization showed that all these mutations caused significant decreases in tryptophan binding activity. Free energy perturbation calculations were performed for the mutants and were consistent with the experimental results. The lack of a side chain at position 85 was concluded to be essential for binding the corepressor; the structure of the binding pocket was suggested to be tight in the vicinity of Gly85.

Angiogenic activity of human villi and decidua in the first trimester of pregnancy

Angiogenic activity in the extracts of human villi and decidua in the first trimester of pregnancy was examined using chorioallantoic membrance assay. Blood vessel density on the chorioallantoic membrane increased greatly with the addition of villi extract, and slightly by decidua extract. Neovascularization with a spoke wheel appearance was induced by both villi and decidua, and this response pattern by the villi was stronger than that by the decidua. Maternal serum did not induce any vascular response. These results suggested that angiogenic activity was present both in the villi and decidua in the first trimester of pregnancy and that the villi activity was stronger than the decidua.

Localized reduction in 123I-MIBG accumulation in the lung

A patient with old myocardial infarction underwent 123I-MIBG scintigraphy to evaluate the adrenergic nerve system in the heart following the treatment of pneumonia. Decreased accumulation of MIBG was observed in the right lower lung field, corresponding to the area affected by pneumonia, as well as in the left ventricle with myocardial infarction. 99mTc-MAA lung perfusion scan demonstrated hypoperfusion in the region of reduced MIBG uptake. Regional decrease in MIBG uptake in the lung is considered to suggest lung pathology, and lung perfusion scan is recommended to discriminate selective endothelial damage from loss of vascular bed.

[Perioperative management of the patient with hypertrophic obstructive cardiomyopathy]

We experienced the perioperative management of a patient with hypertrophic obstructive cardiomyopathy, who underwent open heart surgery. We performed three kinds of overload examinations, which included overdrive test using the pacemaker, continuous dopamine infusion with overdrive test and continuous diltiazem infusion with overdrive test, before and after cardio-pulmonary bypass under observation of the cardiac performances with transesophageal echocardiogram. We gained some important and interesting informations about the cardiac reserve of the patient. We could perform adequate perioperative management for the patient, taking the results of overload examinations into consideration.

SPECT measurements of cerebral blood volume before and after acetazolamide in occlusive cerebrovascular diseases

Cerebral blood volume before and after acetazolamide was measured by SPECT to evaluate cerebral vasodilatory capacity in eight patients with cerebrovascular disease and five control subjects. Two SPECT measurements were performed serially, and acetazolamide was administered between them. The ratio of increase in hemispheric blood volume was calculated, and it was compared with the results of cerebral blood flow and cerebral blood volume measurements. A cerebral vasodilatory capacity map, the image after acetazolamide minus the baseline image, was also produced. Acetazolamide increased hemispheric blood volume in all unilateral carotid disease than in the uninvolved hemispheres of the patients and control subjects. The ratio of concordance with blood flow and blood volume measurements was approximated at 80%. Cerebral vasodilatory capacity mapping revealed three defects compatible with the clinical data. SPECT measurements of cerebral blood volume after acetazolamide can be performed following baseline SPECT with no additional radiotracer, and may be helpful to assess hemodynamic status.

Impaired hepatic function in segmental biliary obstruction demonstrated with a receptor-binding radiotracer

A patient with cholangiocarcinoma underwent left-sided cholangiojejunostomy, and hepatic functional imaging with a receptor-binding radiotracer and SPECT was performed to evaluate the distribution of functional reserve. It revealed decreased accumulation in the regions with residual dilatation of the intrahepatic bile ducts, indicating several kinds of focal damage in hepatic function caused by segmental biliary obstruction. The radioligand may be useful in assessing regional hepatic function, and the high spatial resolution provided by SPECT appears to play an important role for this purpose.

[Effect of pirenzepine on gastric mucosal blood flow in patients after cardiac surgery]

Effect of pirenzepine on gastric mucosal blood flow (GMBF) in adult patients after coronary artery bypass grafting and mitral and aortic valve replacement was evaluated by using endoscopic laser-Doppler velocimetry. Heart rate, blood pressure and cardiac output increased temporarily after intravenous administration of pirenzepine 20 mg. GMBF also increased with these hemodynamic changes. However, GMBF remained significantly higher even after the decrease of cardiac output. Therefore, the increase in GMBF, which might be due in part to increase in cardiac output, could be explained by pirenzepine's own effect on gastric mucosa. Since the GMBF is one of the most important gastric mucosal defensive factors, pirenzepine may be useful in preventing acute gastric mucosal lesions in patients with low cardiac output.

[Evaluation of a new nitric oxide delivery system during mechanical ventilation]

A new nitric oxide delivery and continuous monitoring system is described. During mechanical ventilation, this new system connected with Siemens Servo 900C ventilator was shown to be able to provide a constant inspired NO concentration (10-100 ppm) using chemiluminescence technique for NO analysis. Gas was analysed at the mixing chamber in front of the ventilator inlet and inspiratory tube connected with the soda-lime carbon-dioxide absorber. Both NO concentrations showed a good correlation (r = 0.99). The actual NO concentration from the NO supply cylinder was 1154 ppm and NO2 concentration was 14 ppm. In mongrel dogs, after 20 minutes of NO inhalation (10-100 ppm), the blood methemoglobin level reached a peak value of 2.2% starting from the pre-inhalation level of 0%. To optimize the safety of the clinical application of NO, its concentration should be measured continuously with chemiluminescence technique.

Assessment of the cerebrovascular response to acetazolamide using 99mTc-DTPA-HSA: methodological considerations

We have reported methods of assessing the cerebrovascular response to acetazolamide using 99mTc-DTPA-HSA and their usefulness in evaluating cerebral hemodynamics. Several problems of this technique were investigated in 10 normal subjects. Following 99mTc-DTPA-HSA injection, dynamic imaging of the anterior head view was performed for 25 to 50 minutes, and 10 minutes after the beginning of imaging, 1,000 mg of acetazolamide was infused intravenously. Venous blood samples were obtained during the imaging period to estimate the blood retention of 99mTc-DTPA-HSA. Radioactivity in the head increased for about 10 minutes following acetazolamide infusion, then decreased slowly. The declining phase almost disappeared after correction for the blood clearance of 99mTc-DTPA-HSA, indicating stability of the vasodilatory effect of acetazolamide. Dilatation index, the percent increase in activity, was a little smaller after correction, but was closely correlated with the index without correction. There was a high correlation between dilatation indices obtained by two analyses, including ROI setting and visual determination of the peak, of the same data. In conclusion, neither blood clearance of 99mTc-DTPA-HSA nor subjective analysis considerably impairs the reliability of the dilatation index, and blood volume in the head from about 15 to 40 minutes after acetazolamide injection is stable and suitable for SPECT.

[Clinical experience of extracorporeal life support with the use of centrifugal pump ECMO]

Many reports have documented the good results with the use of extracorporeal life support in severe respiratory and circulatory failure. In our institution, we have used the centrifugal pump (Bioconsol 540: Biomedicus Co. Ltd.) ECMO for extracorporeal life support, and obtained good results in three cases. We used V-V bypass ECMO in one case (idiopathic interstitial pneumonia) and V-A by-pass ECMO in other two cases (ARDS and meconium aspiration syndrome). Duration of total bypass in three cases were 34, 51 and 140 hours, respectively. Recent reports on the use of centrifugal pump have indicated that it can bring excellent results of circulatory assist for cardiogenic shock. Compared to the roller pump method, the use of centrifugal pump ECMO was very simple, and could serve as an effective method for providing improvement in a relatively short period.

In vitro effects of trapidil on fatty acid and prostaglandin metabolism in platelets

The effects of trapidil, a coronary vasodilator and platelet aggregation inhibitor, on fatty acid metabolism and prostaglandin (PG) formation in platelets were studied using platelet suspensions from six normal subjects. The addition of trapidil to fatty acids in platelet phospholipids decreased palmitoleic acid and arachidonic acid, and increased an unidentified substance, X2 (palmitoleic acid, P < 0.05; arachidonic acid, P < 0.05; X2, P < 0.05). Thrombin stimulation following the addition of trapidil resulted in an increase in stearic acid and a decrease in arachidonic acid, compared with the trapidil-free control samples (stearic acid, P < 0.05; arachidonic acid, P < 0.02). The addition of trapidil tended to increase immunoreactive PGE (iPGE) and iPGF dose-dependently. On the other hand, thrombin stimulation following the addition of trapidil decreased the formation of thromboxane B2 (TXB2) significantly compared with the levels of TXB2 in the trapidil-free samples (10 micrograms/mL trapidil, P < 0.005, 100 micrograms/mL trapidil, P < 0.001). These results show that trapidil increased arachidonic acid mobilization in the platelets.

Erythropoietin production in patients with chronic renal failure

Studies were performed to reexamine the response of erythropoietin (Epo) production to acute hypoxic stimuli in patients with end-stage renal disease (ESRD). In the absence of acute bleeding or hypoxia, the serum Epo level in ESRD was similar to that of normal subjects despite severe anemia. In 11 dialysis patients with acute bleeding, the decrease in the Hb level from 8.9 to 5.8 g/dL provoked a significant increase in serum Epo up to 52.2 times the normal value. The increase in serum Epo was associated with a significant increase in corrected reticulocyte. Systemic hypoxemia (PaO2 < 65 mm Hg) in 8 dialysis patients provoked a significant elevation in the serum Epo level up to 24.6 times the normal level. There was an inverse relationship between serum Epo and arterial PaO2 (r = -0.715). The serum Epo level in these patients declined to or near the normal value after recovery from acute hypoxic stress. These data suggest that the ability of the Epo production is well preserved in ESRD, indicating that acute hypoxic stimuli provoke a significant increase in serum Epo.