Lack of inhibitory effects of the Ju-myo protein on development of glutathione S-transferase placental form-positive foci in the male F344 rat liver

The effects of the 77 kDa Ju-myo protein, isolated from Drosophila melanogaster, on the development of glutathione S-transferase placental form (GST-P) positive foci in the male F344 rat liver were evaluated using a medium-term bioassay system. No modifying potential was evident in terms of the numbers or areas of GST-P positive foci. Ju-myo protein did not exert any influence on cell proliferation, as reflected by ornithine decarboxylase (ODC) or spermidine/spermine N1-acetyltransferase (SAT) activity and BrdU labeling. These results demonstrated that Ju-myo protein is unlikely to have inhibitory or promoting effects on rat liver carcinogenesis.

Role of platelet activating factor on severity of ischemic colitis

PURPOSE

Ischemic colitis develops after a sudden decrease in colonic blood supply and has a variety of clinical manifestations. The aim of this study was to assess the role of platelet activating factor in the pathogenesis of ischemic colitis with use of the platelet activating factor antagonist TCV-309.

METHODS

Rats were randomly divided into four groups. Rats in Group RV underwent ring attachment around the rectum to induce partial obstruction and ligation of the marginal vessels of the left colon. As control, rats in Group R underwent the ring attachment and rats in Group V underwent the vascular ligation. Rat in Group C underwent sham operation. The effects of TCV-309 on lesion formation in the colon were evaluated. Thiobarbituric acid reactant level was determined in colonic mucosa, and the incidence and severity of ischemic lesions were also determined.

RESULTS

Lesions of colitis were frequently observed in Group RV. TCV-309 did not prevent lesion formation, nor did it suppress the increase in thiobarbituric acid reactant level in Group RV. However, TCV-309 mitigated the severity of the lesion.

CONCLUSIONS

Partial obstruction of the colon tends to induce ischemic colitis, and additional ischemia completes lesion formation. Platelet activating factor may play a role in the progression of ischemic lesions.

Selectively induced high MRP gene expression in multidrug-resistant human HL60 leukemia cells

A subclone HL60/DOX was selected from a human leukemic HL60 cell line for resistance to doxorubicin (DOX) by exposure to stepwise increasing concentrations of the drug and coexposure to a potential P-glycoprotein (P-gp) inhibitor, cepharanthine (a biscoclaurine alkaloid). Compared with the parent HL60 cells, the HL60/DOX cells were 13.0-fold more resistant to DOX and showed multidrug-resistant (MDR) phenotype characterized by 4.6-fold, 2.3-fold, and 5.7-fold cross-resistance to vincristine, pirarubicin, and etoposide, respectively, but no cross-resistance to alkylating agent, cisplatin. Immunocytochemical analyses using the specific monoclonal antibody, MRPr1, and quantitative analyses using a competitive reverse transcription-polymerase chain reaction (CRT-PCR) confirmed overexpression of MRP gene products (about 8-fold determined by CRT-PCR) in this resistant clone. The P-gp expression was not detectable by the monoclonal antibody, C219, in the HL60/DOX cells, and that was consistent with extremely low levels of mdr1 mRNA expression determined by CRT-PCR in this clone. Drug accumulation and efflux studies demonstrated the significantly increased efflux rate of DOX compared to the parent HL60 cells. This enhancement of DOX efflux was reversed by the addition of 10 microM verapamil. To investigate the additional underlying mechanisms contributing to MDR phenotype in the HL60/DOX cells, the levels of DNA topoisomerases (Topo) including Topo I, Topo IIalpha, and Topo IIbeta, and gamma-glutamylcystein synthetase (y-GCS) expression were determined using CRT-PCR techniques. Normal expression of each enzyme at the transcriptional level was demonstrated in this resistant clone. Southern blot analysis of the gene organization in the HL60/DOX cells revealed the amplification of MRP gene. These results indicate that alteration of the drug accumulation from enhanced efflux appears to be a major mechanism(s) of MDR phenotype and attributable to high levels of MRP expression in the HL60/DOX cells. Overexpression of MRP in this clone is regulated by the genomic amplification of DNA and increased levels of the MRP mRNA, independently with the normal expression of Topo I, Topo IIalpha, Topo IIbeta, or gamma-GCS.

Membrane-type matrix metalloproteinase-1 expression and activation of gelatinase A as prognostic markers in advanced pediatric neuroblastoma

BACKGROUND

Recently a novel membrane-type matrix metalloproteinase-1 (MT-MMP-1) was discovered to be a specific activator of progelatinase A, and was correlated with tumor invasion. To the authors' knowledge, no information regarding the expression of MT-MMP-1 has been reported in childhood malignancies. In this study, the authors attempted to elucidate the specific mechanisms that underlay the invasive behavior of neuroblastoma (NB) cells with respect to the expression of MT-MMP-1 and its determined prognostic value, especially in pediatric patients with advanced Evans' Stage IV NB.

METHODS

Thirty specimens from surgically excised NB (mainly Stage IV) were collected retrospectively. The total levels of progelatinase A (68 kilodaltons [kD]) and its activated form (62 kD) in the tumor lysates were quantified by gelatin zymography. The expression of MT-MMP-1 was estimated by immunostaining with a monoclonal antibody (113-5B7).

RESULTS

Progelatinase A and the activated form were detected in each of the 30 specimens. The gelatinase A activation ratio, 62 kD/(62 kD + 68 kD), strongly correlated with the high levels of MT-MMP-1 expression found in specimens of advanced tumor stage. In the patients with advanced Stage IV NB, the activation ratio was strongly associated with unfavorable clinical outcome; the 5-year survival was 88.9% in the patients with a low activation ratio (< or = 26%) versus only 21.2% in the patients with a high activation ratio (>26%).

CONCLUSIONS

Gelatinase A activation correlates with high expression of MT-MMP-1 on NB cells and is associated strongly with advanced stage and poor clinical outcome. These results are consistent with the notion that MT-MMP-1 expression is an important prognostic determinant of the biologic behavior of NB.

[The investigation of surgical procedures for post infarcted ventricular septal defects: a comparison between Daggett and David method]

Post infarcted ventricular septal perforations (VSP) has diverse clinical and pathological manifestations and the surgical results in severe cases have not yet been satisfactory. In the past we had performed the procedure of Daggett. However since 1992 we have also introduced the procedure of infarction exclusion technique proposed by David which involves plastering the ventricular cavity in a large patch without infarcted myotomy. We reported 5 cases treated with David method, 5 cases with Daggett method, and their results were compared. There were four mortality cases in Daggett method and three in David method. No significant difference was observed regarding the surgical mortality. However, there were different post-operative features between the two groups. In Daggett method patients had prolonged heart failure and LOS. In David method patients, had no severe LOS, but residual shunt were recognized in two cases. We think that the emergence of residual shunt in David method was probably due to suturing without prior removal of the damaged fragile infarcted myocardium. In Daggett method there were death cases caused by LOS and postoperative heart failure but without residual shunts. Despite its recent growing popularity for treating VSP, our experience suggests that residual shunt is an important issue remains to be solved in David method.

Simultaneous acquisition of iodine-123 emission and technetium-99m transmission data for quantitative brain single-photon emission tomographic imaging

The aim of this study was to obtain quantitative iodine-123 brain single-photon emission tomographic (SPET) images with scatter and attenuation correction. We used a triple-headed SPET gamma camera system equipped with fan-beam collimators with a technetium-99m line transmission source placed at one of the focal lines of the fan-beam collimators. Four energy windows were employed for data acquisition: (a) 126-132 keV, (b) 132-143 keV, (c) 143-175 keV and (d) 175-186 keV. A simultaneous transmission-emission computed tomography scan (TCT-ECT) was carried out for a brain phantom containing 123I solution. The triple energy window scatter correction was applied to the 123I ECT data measured by means of the windows (b), (c) and (d) acquired by two detectors. Attenuation maps were reconstructed from 99mTc TCT data measured by means of the windows (a), (b) and (c) acquired by one detector. Chang's iterative attenuation correction method using the attenuation maps was applied to the 123I ECT images. In the phantom study cross-calibrated SPET values obtained with the simultaneous mode were almost equal to those obtained with the sequential mode, and they were close to the true value, within an error range of 5.5%. In the human study corrected images showed a higher grey-to-white matter count ratio and relatively higher uptake in the cerebellum, basal ganglia and thalamus than uncorrected images. We conclude that this correction method provides improved quantification and quality of SPET images and that the method is clinically practical because it requires only a single scan with a 99mTc external source.

Yolk sac tumor with a unique uniform hepatoid pattern histology

BACKGROUND

Yolk sac tumors (YST) exhibit several different histological subtypes and the mechanisms of cellular differentiation and prognosis of each subtype remain unknown.

RESULTS

We report two infants with sacrococcygeal YST; one represented a typical histological subtype and the other showed a hepatoid subtype with uniform histology. The isoform of alpha-fetoprotein (AFP) in the patient with the hepatoid pattern was examined by lectin-affinity immunoelectrophoresis and represented as a YST, but not hepatocellular, subtype. The patient with typical YST responded well to VAB-6 combination chemotherapy. However, this regimen was only partially effective to the patient with the pure hepatoid histological subtype, and an etoposide with ifosfamide and cisplatin (VIP) regimen as a salvage chemotherapy combined with complete tumor resection was useful to achieve complete remission (CR). Both of the patients have been in CR for more than four years.

Clinical usefulness of CA-19-9 in pancreatic carcinoma

Preoperative and postoperative serum levels of carbohydrate antigen-(CA)19-9 in 148 patients with carcinoma of the pancreas were studied. All 18 patients with carcinoma of the pancreas of Stage I, II, and III were resectable, and their pre-operative serum levels of CA-19-9 were under 1,344 U/ml. Pre-operative serum levels of CA-19-9 in patients with Stage IV ranged widely between 5 and 32,240 U/ml. The postoperative survival rate was significantly superior in patients (n = 15) whose CA-19-9 pre-operative serum levels were less than 2,000 U/ml compare to those (n = 64) whose levels were over that level. Fifteen resectable patients who showed serum levels of CA-19-9 over 2,000 U/ml pre-operatively died within 2 years postoperatively due to recurrence, especially by liver metastasis in spite of aggressive surgery. Intraoperative quick immunostaining of CA-19-9 and carcinoembryonic antigen (CEA) was useful to diagnose intrapancreatic carcinoma development on frozen sections of cut margin of the pancreas and also useful in abdominal washing cytology combined with conventional staining.

Presence of a threshold for promoting effects of phenobarbital on diethylnitrosamine-induced hepatic foci in the rat

The dose dependence of the hepatopromoting effects of phenobarbital (PB) was investigated in a rat liver medium-term bioassay (Ito test) to elucidate a practical threshold level. F344 rats were given a single i.p. injection of diethylnitrosamine (200 mg/kg body wt) and subjected to two-thirds partial hepatectomy at week 3. Commencing 2 weeks from the start, PB at doses of 0, 1, 2, 4, 7.5, 15 or 500 p.p.m. in experiment 1 and 0, 0.01, 0.1 or 0.5 p.p.m. in experiment 2 were fed to the rats for 6 weeks. Experiment 3 was conducted to confirm previous data using the same medium-term bioassay, with PB at doses of 0, 1, 2, 4, 7.5, 15, 30, 60, 125, 250 or 500 p.p.m. fed to the rats. All surviving animals were killed at week 8 in these experiments and their livers were immunohistochemically examined for expression of glutathione S-transferase placental form (GST-P). Quantitative values for GST-P-positive foci in the liver were increased dose dependently in rats given 60-500 p.p.m. PB. However, those for doses in the range 1-7.5 p.p.m. demonstrated a decrease as compared with the control group (0 p.p.m.), with significant differences observed for 1 and 2 p.p.m.. The results for 15-30 and 0.01-0.5 p.p.m. were comparable with the control values. Examination of transforming growth factor-alpha (TGF-alpha)-positive foci also produced similar results to those for GST-P in experiment 1. Immunohistochemical staining of TGF-alpha and GST-P using serial liver sections demonstrated that the TGF-alpha-positive foci comprised a sub-population of the GST-P-positive lesions, being approximately 1/8-1/10th as common in livers of animals treated with PB. TGF-alpha-positive foci were almost always negative on immunostaining for TGF-beta. Western blotting for proteins CYP2B1, 2C6 and 3A2 revealed a good correlation between changes in GST-P-positive foci and CYP3A2 protein expression. The finding of inhibition effects at low doses of PB confirms the presence of a threshold level for promoting effects by PB on liver carcinogenesis in rats.

Spinal canal involvement in infantile myofibromatosis: case report and review of the literature

PURPOSE

An unusual case of infantile myofibromatosis with spinal canal involvement is reported and the literature is reviewed.

PATIENT AND METHODS

A female neonate had bladder and bowel dysfunction and paresis of the lower extremities.

RESULTS

Intrapelvic and paravertebral masses with extension into the spinal canal were detected by imaging studies. In addition, radiologic examination showed multiple metaphyseal radiolucent lesions of the long bones and pathologic fracture of the left femur. The histopathologic diagnosis of the paravertebral tumor and bone lesions was infantile myofibromatosis. Surgical resection of the paravertebral and intrapelvic masses was performed to improve her neurologic impairments. Paresis of the lower limbs gradually improved, whereas bladder and bowel dysfunction remained unchanged.

CONCLUSIONS

Only six cases of infantile myofibromatosis associated with spinal canal involvement have been reported. Three patients with flaccid paresis of extremities and respiratory distress died in the newborn period. The other three patients showed improvement of the paresis. The prognosis of infantile myofibromatosis without visceral complication is generally good, but neurologic impairment may occur at birth if the spinal cord is compressed.

Clinical usefulness of CA-19-9 in pancreatic carcinoma

Preoperative and postoperative serum levels of carbohydrate antigen-(CA)19-9 in 148 patients with carcinoma of the pancreas were studied. All 18 patients with carcinoma of the pancreas of Stage I, II, and III were resectable, and their pre-operative serum levels of CA-19-9 were under 1,344 U/ml. Pre-operative serum levels of CA-19-9 in patients with Stage IV ranged widely between 5 and 32,240 U/ml. The postoperative survival rate was significantly superior in patients (n = 15) whose CA-19-9 pre-operative serum levels were less than 2,000 U/ml compare to those (n = 64) whose levels were over that level. Fifteen resectable patients who showed serum levels of CA-19-9 over 2,000 U/ml pre-operatively died within 2 years postoperatively due to recurrence, especially by liver metastasis in spite of aggressive surgery. Intraoperative quick immunostaining of CA-19-9 and carcinoembryonic antigen (CEA) was useful to diagnose intrapancreatic carcinoma development on frozen sections of cut margin of the pancreas and also useful in abdominal washing cytology combined with conventional staining.

Interactions: timing and force control of finger-tapping sequences

This study examined effects of combinations of intertap interval and muscle force on interactions between two factors in sequences of equally paced finger taps. 12 male college students tapped a force plate connected to strain gauges. Subjects firstly tapped the plate at a preferred pace and force for 12 sec. Next, subjects tapped the plate by half or double the preferred pace. A series of finger-tapping tasks the consisted of nine combinations of pace and force. Analysis showed that, although variations in intertap interval were considerably accurately controlled across conditions, those in peak forces were not. Movement timing of tapping sequences hence appeared to be independent of force control. For six of 12 subjects, on the other hand, positive correlations between spontaneous variations in intertap interval and in forces were noted. Then, although motor timing was independent of force control in controls of low pace and weak forces, there were strong interactions between the two factors under high pace conditions.

[Outcome of emergency surgery for Stanford type A aneurysms: selection of operative procedures and supported systems of cerebral protection]

Fourteen surgical cases of acute dissecting aneurysms of Stanford type A were reported. Clinical symptoms, operative methods, pathophysiology, cerebral protection, supported systems, and prognosis were examined. All patients underwent surgery within 5 days of symptom onset. The patient population consisted 8 males and 6 females with a mean age of 56.6 years. Ascending aortic replacement was performed using a vascular graft 12 patients. ECC was performed under deep hypothermia. Femoral artery cannulation and retrograde cerebral perfusions was performed in all cases. The ascending aorta was the site of entry in 13 of the 14 cases. Whenever feasible, enhanced CT and aortography were performed to confirm the entry lesion. Two patients expired. One patient died intraoperatively due to massive bleeding. The other patient, while hospitalized, experienced a cerebrovascular accident and died due to pneumonia. All other patients ran an uneventful post-operative course without cerebrovascular accident. In conclusion we think that although ascending aorta replacement using prosthetic grafts is not ideal for patients with Stanford type A dissecting aneurysms, it is a viable option for emergency cases. We found retrograde circulatory cerebroplegia (RCCP) to be satisfactory for brain protection during these emergency procedures.

[Successful removal of a giant ball thrombus in the left atrium in an aged patient with unusual course]

A case of left atrial ball thrombus associated with severe mitral stenosis was reported. This male patient, aged 78, came in the chief complaint of leg and facial edema. An echocardiographic examination revealed the presence of mitral stenosis and floating giant ball thrombus in the atrium. He suffered from acute thromboembolism in his right leg six years ago and had been treated with anticoagulant since then. Despite this a floating giant ball thrombus was observed. Emergency operation including mitral valve replacement and thrombectomy was successfully performed. Thrombus formation in the left atrium is not uncommon but it is very rare to encounter in patients receiving anticoagulant therapy. To manage these patients well, meticulous attention must be paid during induction of anesthesia, intra-operative procedures, perioperative care, and operative position.

[Dor operation for end-stage ischemic cardiomyopathy]

Endoventricular circular patch plasty (Dor operation) was used to treat end-stage dilated ischemic cardiomyopathy in 13 patients from January to December, 1997. There were 10 men and three women aged from 57 to 78 years (mean 63 years). Single, double, triple and left main trunk coronary disease was present in one, two, eight and two patients, respectively. Mean ejection fraction was 22% (6-30%) and signs of congestive heart failure were clear in all patients [New York Heart Association (NYHA) class III in eight patients and class IV in five patients]. Angina pectoris was present in five patients. Six patients had associated significant mitral regurgitation. Coronary artery bypass grafting (mean 3.2 grafts) was used in 11 patients and mitral valve reconstruction was performed in 6 patients (4: replacement and 2: repair) combined with akinetic area exclusion by the Dor technique. All patients were successfully weaned from cardiopulmonary bypass without mechanical support and no perioperative death occurred. Three patients died in hospital at 1-2 postoperative months due to pneumonia, stroke and heart failure, respectively. Two patients died during the late period due to stroke and sudden death. Among the eight survivors, six patients were in NYHA class I-II and two patients in class III. Ejection fraction increased from 22% to 36%, end-diastolic and systolic volume indices decreased from 168 +/- 58 to 123 +/- 39 ml/m2 and from 131 +/- 60 to 81 +/- 33 ml/m2, respectively. Pulmonary capillary wedge pressure decreased from 19 +/- 10 to 14 +/- 5 mmHg. The Dor procedure is an effective surgical alternative for patients with end-stage ischemic cardiomyopathy who are considered to be candidates for cardiac transplantation.

Left ventriculoplasty: a new option for end-stage cardiomyopathy

To treat end-stage dilated cardiomyopathy, we have performed volume reduction left ventriculoplasty (as introduced by Randas Batista in Brazil) in four patients since December 1996. All patients had end-stage idiopathic cardiomyopathy. Mitral valve replacement was also performed in three patients. In all four patients, improvement of left ventricular function was noted. One patient died of respiratory failure on the 12th postoperative day. The other three patients recovered successfully from the operation (i.e., they were discharged from hospital with the functional status in New York Heart Association Class I or II). We conclude that the Batista operation provides a real hope for patients with end-stage dilated cardiomyopathy.

[Early result of volume reduction left ventriculoplasty (Batista operation) for dilated cardiomyopathy]

The Batista operation is intended to improve cardiac function by reducing the diameter of the left ventricle by excising of a sizable amount of the left ventricular free wall. Candidates for this operation are patients awaiting cardiac transplantation due to end-stage dilated cardiomyopathy and those unsuitable for transplantation because of age, physical or economical reasons. We performed this operation in 10 patients between December 1996 and October 1997. The baseline indication is left ventricular diastolic dimension > or = 70 mm and New York Heart Association (NYHA) class III or IV. There were eight men and two women aged from 16 to 60 years (mean 46 years). All had non-ischemic cardiomyopathy including seven idiopathic and one each of hypertrophic, arrhythmogenic right ventricular and valvular (sarcoidosis) cardiomyopathy. Eight patients were in NYHA class IV and six needed inotropic drip therapy prior to the operation. Nine patients had significant mitral regurgitation and six had tricuspid insufficiency concomitantly. Eight patients underwent mitral valve replacement and one was treated with mitral valve plasty. Six patients also had tricuspid plasty combined with partial left ventriculectomy. Eight patients survived. Mean value of left ventricular end-diastolic diameter was reduced from 77.8 mm to 59.8 mm, left ventricular end-diastolic volume index was reduced from 189.3 to 99.2 ml/m2, ejection fraction was increased from 19.0% to 33.8% and NYHA class improved from 3.8 to 1.8. Six months later, left ventricular dilatation was not noticed in four patients examined. The Batista operation offers real hope for patients with end-stage dilated cardiomyopathy, but we still have much to learn.

Application of transmission scan-based attenuation compensation to scatter-corrected thallium-201 myocardial single-photon emission tomographic images

A practical method for scatter and attenuation compensation was employed in thallium-201 myocardial single-photon emission tomography (SPET or ECT) with the triple-energy-window (TEW) technique and an iterative attenuation correction method by using a measured attenuation map. The map was reconstructed from technetium-99m transmission CT (TCT) data. A dual-headed SPET gamma camera system equipped with parallel-hole collimators was used for ECT/TCT data acquisition and a new type of external source named "sheet line source" was designed for TCT data acquisition. This sheet line source was composed of a narrow long fluoroplastic tube embedded in a rectangular acrylic board. After injection of 99mTc solution into the tube by an automatic injector, the board was attached in front of the collimator surface of one of the two detectors. After acquiring emission and transmission data separately or simultaneously, we eliminated scattered photons in the transmission and emission data with the TEW method, and reconstructed both images. Then, the effect of attenuation in the scatter-corrected ECT images was compensated with Chang's iterative method by using measured attenuation maps. Our method was validated by several phantom studies and clinical cardiac studies. The method offered improved homogeneity in distribution of myocardial activity and accurate measurements of myocardial tracer uptake. We conclude that the above correction method is feasible because a new type of 99mTc external source may not produce truncation in TCT images and is cost-effective and easy to prepare in clinical situations.

Increased lung uptake of iodine-123-MIBG in diabetics with sympathetic nervous dysfunction

Scintigraphy with 123I-MIBG and 201TI was compared in patients with various diseases including diabetes mellitus, with and without sympathetic nervous dysfunction. This study was done to assess lung uptake of these tracers semiquantitatively.

METHODS

Thirty-eight patients with diabetes mellitus, seven patients with dilated cardiomyopathy (DCM), 12 patients with hypertrophic cardiomyopathy (HCM) and eight healthy subjects were studied. Sympathetic nervous dysfunction was observed in 13 of the 38 diabetic patients. Simultaneous imaging with 123I-MIBG and 201TI was performed. The ratio of lung to total injected dose count and washout rate in the lung were calculated from dynamic images acquired in the initial 2 min and static images acquired at 15 min and at 4 hr after injection of the tracers.

RESULTS

Lung uptake of 123I-MIBG at 4 hr was significantly increased in the diabetic group as compared with those in the other groups. In diabetic patients with sympathetic nervous dysfunction, the lung uptake ratio of 123I-MIBG at 4 hr was significantly higher than that in the diabetic patients without sympathetic nervous dysfunction, due to decreased clearance of 123I-MIBG from the lung. On the other hand, increased lung uptake of 201TI was observed in DCM patients at both 15 min and 4 hr. There was no significant difference between lung uptake of 201TI in diabetic patients and that in healthy subjects.

CONCLUSION

Lung uptake of 123I-MIBG was increased and lung washout of 123I-MIBG was decreased in diabetic patients with sympathetic nervous dysfunction, while lung uptake of 201TI was not altered. lodine-123-MIBG scintigraphy of the lung may provide information on sympathetic nervous activity in diabetic patients. It is a promising method for studying the kinetics of norepinephrine in the lung because MIBG is taken up in the lung by the same mechanism as norepinephrine.

[Determination of energy window width and position for the triple energy window (TEW) scatter compensation method]

Since primary photons can provide information concerning the position of radioisotope (RI) accumulation and the energy of the photons, it would seem reasonable to vary the position and width of the energy window depending on the type of RI and the energy resolution of the detector to collect as many of the primary photons as possible. We propose a method for determining energy window width and position for scintigraphic imaging to collect as many of the primary photons as possible, and studied the influence on the Triple Energy Window (TEW) scatter compensation method of setting such energy window levels for 99mTc (single photopeak) and 201Tl (multiple photopeaks) using detector with different energy resolution through simulation. The Monte Carlo simulations were verified by comparing the regional energy spectrum at the phantom obtained from the simulation against experimental measurements. The energy window with our proposed method for 99mTc is 20% and 47.3% for 201Tl using gamma camera, and 9.8% for 99mTc using a semiconductor detector with a theorized energy resolution of 7.0 keV.

Promotion of rat hepatocarcinogenesis by dimethylarsinic acid: association with elevated ornithine decarboxylase activity and formation of 8-hydroxydeoxyguanosine in the liver

Arsenicals are epidemiologically significant chemicals in relation to induction of liver cancer in man. In the present study, we investigated the dose-dependent promotion potential of dimethylarsinic acid (DMAA), a major metabolite of inorganic arsenicals in mammals, in a rat liver carcinogenesis model. In experiment 1, glutathione-S-transferase placental form (GST-P)-positive foci, putative preneoplastic lesions, were employed as endpoints of a liver medium-term bioassay for carcinogens (Ito test). Starting 2 weeks after initiation with diethylnitrosamine, male F344 rats were treated with 0, 25, 50 or 100 ppm of DMAA in the drinking water for 6 weeks. All animals underwent two-thirds partial hepatectomy at week 3 after initiation. Examination of liver sections after termination at 8 weeks revealed dose-dependent increases in the numbers and areas of GST-P-positive foci in DMAA-treated rats as compared with controls. In experiment 2, ornithine decarboxylase activity, which is a biomarker of cell proliferation, was found to be significantly increased in the livers of rats treated with DMAA. In experiment 3, formation of 8-hydroxydeoxyguanosine, which is a marker of oxygen radical-mediated DNA damage, was significantly increased after administration of DMAA. These results indicate that DMAA has the potential to promote rat liver carcinogenesis, possibly via a mechanism involving stimulation of cell proliferation and DNA damage caused by oxygen radicals.

[Successful emergency surgical management following cardiac massage in a patient with acute myocardial infarction due to total obstruction of the left main trunk]

The prognosis in patients manifesting shock following acute myocardial infarction due to total occlusion of the left main trunk (LMT) is usually very poor and so is the lifesaving rate. Accurate judgement and rapid response are key to the successful management of this disease. We experienced a successful case with emergency coronary artery bypass grafting (CABG) on the 14 the day after initial attack. The patient, who had total occlusion of LMT, underwent a PTCA (percutaneous transluminal coronary angioplasty) during the initial attack under cardiac massage. We think in situations where patients have cardiac arrest, shock, elevated CPK levels suggesting devastation of myocardium due either to LMT or severe triple vessels disease, early catheter intervention rather than emergency CABG would be much more tolerable as long as hemodynamic situation allows. Our previous experience taught us that immediate surgical intervention with CABG usually resulted in poor outcome. Further refinements regarding the surgical procedure, technique, assist circulatory supports, cardioplegia, etc., are indispensable before trying to have a successful emergency CABG.

[Antitumor effect of S-1 and cisplatin treatment against human gastric cancer xenografted in nude mice]

The enhanced effects due to the combined use of oral administration of S-1 and intraperitoneal administration of Cisplatin (CDDP) were examined with gastric cancer xenografts (NUGC 4). S-1, a new anticancer drug, was daily administered at 10 mg/kg (qld x 5 x 3 weeks). 5-FU level in blood was 1 microgram/ml at two hours after the treatment. Antitumor activity was not found in mice with only the CDDP treatment. But antitumor activity by S-1 and daily low-dose (1 mg/kg) or intermittent treatment (5 mg/kg) of CDDP showed better results than daily S-1 treatment. The daily low-dose CDDP treatment showed similar efficacy to the intermittent administration at the same total dose, but the daily low-dose CDDP treatment was better in the light of toxicities. These results suggest that treatment with S-1 and daily low-dose CDDP was effective for gastric cancer.

The omental flap with skin grafting for treatment of a difficult sternal closure

A case report of difficult sternal closure is described. Chest closure following cardiac operation in critically ill patients can be a problem. Techniques have been described so that sternal closure can be delayed until the patient is hemodynamically stable and hemostasis has been achieved. However, in some instances, the sternal closure can not be performed because of prolonged cardiopulmonary instability. We describe the use of transposition of an omental flap with skin grafting in a 74-year-old patient with aortic valve stenosis, poor pulmonary function, and a thoracic deformity. This technique enabled incomplete sternal closure which maintained hemodynamic stability.

Overcoming of multidrug resistance by VA-033, a novel derivative of apovincaminic acid ester

We have studied the effects of a novel derivative of apovincaminic acid ester, VA-033, on the resistance of tumors to chemotherapeutic agents. VA-033 increased the sensitivity of drug-resistant cell lines (P388/VCR, P388/ADM, AD10, and K562/ADM) to adriamycin or vincristine. The potency of VA-033 was stronger than verapamil. The drug lengthened the survival time of the P388/VCR-implanted mice treated with vincristine. VA-033 increased the intracellular accumulation of vincristine in the tumor cells, and the photolabeling of P-glycoprotein by [3H]azidopine was inhibited by VA-033. VA-033 showed a slight inhibitory effect on the L-type Ca2+ current in the ventricular myocytes, and had less effect on the cardiovascular parameters such as blood pressure, contractile force and atrio-ventricular conduction time than verapamil when administered systemically in the dog. These results suggest that VA-033 may become a beneficial compound as a modifier to the neoplastic cell resistant to multidrugs.