Drug-induced down-regulation of topoisomerase I in human epidermoid cancer cells resistant to saintopin and camptothecins

The anticancer agent saintopin induces DNA cleavage mediated by both topoisomerase (topo) I and topo II in vitro through stabilization of the reversible enzyme-DNA cleavable complex. We established saintopin-resistant cell lines (KB/STP-1 and KB/STP-2) from human epidermoid cancer KB cells by stepwise exposure to increasing doses of the drug. KB/STP-1 and KB/STP-2 cells showed 12- and 44-fold increases, respectively, in resistance to saintopin relative to that of KB cells. Both saintopin-resistant cell lines showed only small reductions in sensitivity to the topo II inhibitor etoposide but developed marked cross-resistance to the topo I-targeting camptothecin derivative CPT-11 [(4s)-4,11-diethyl-4-hydroxy-9-[(4-piperidinopiperidino)carbony loxy] dione hydrochloride trihydrate] and its active form, SN-38 (7-ethyl-10-hydroxycamptothecin). In contrast, both KB/STP-1 and KB/STP-2 cells showed increased collateral sensitivity to cisplatin, a nitrosourea derivative, mitomycin C, and UV light. The protein concentration, activity, and mRNA abundance of both topo I and topo II were similar in KB/STP-1, KB/STP-2, and the parental KB cells. There were no significant changes in the drug-stabilized topo-DNA cleavable complex formation in KB and KB/STP-2 cells. Two point mutations were detected in topo I cDNA from KB/STP-2 cells, but these were also present in KB cells. Topo I mRNA abundance decreased markedly immediately after exposure of KB/STP-2 cells to saintopin; no such effects were apparent in KB cells. In contrast, topo II mRNA was not markedly affected by saintopin in either KB or KB/STP-2 cells. Treatment with CPT-11 or SN-38 also induced a markedly greater and more persistent reduction in topo I mRNA abundance in KB/STP-2 cells than in KB cells. Etoposide had no marked effect on topo I mRNA abundance in either KB/STP-2 or KB cells. Topo I mRNA was highly unstable in KB/STP-2 cells in comparison to KB cells when incubated with saintopin. This novel regulation of topo I mRNA by topo I-targeting agents could be associated with acquirement of drug resistance to saintopin or SN-38/CPT-11 in KB/STP-2 cells.

Structural and functional analysis of the human Y-box binding protein (YB-1) gene promoter

We have isolated three overlapping genomic clones containing the 5'portion of the human YB-1 gene. These clones span approximately 25 kb of contiguous DNA containing 10 kb of 5' flanking sequence and 15 kb of the gene. The nucleotide sequence of the first exon and of 2000 upstream base pairs (bp) was determined. The first axon is unusually large and contains a 166 bp coding sequence and a 331 bp untranslated region. CpG sequences cover the 5'-end of the YB-1 gene including its first axon and intron as well as the upstream regions. The GC content around the first exon is approximately 70% and a CpG-free region was located in the untranslated sequence. The segment preceding the major transcription initiation site does not contain a TATA box, CCAAT box and the binding sequence for known transcription factors. A transient expression assay using the chloramphenicol acetyltransferase (CAT) gene showed that the sequence from +24 to +281 was critical for CAT expression. Fluorescence in situ hybridization demonstrated the chromosomal locus of YB-1 gene on chromosome 1p34. Polymerase chain reaction analysis on other genomic phage DNAs showed that several clones were derived from pseudogenes.

Identification of a 450-kDa human epidermal autoantigen as a new member of the plectin family

The serum from an individual with a subepidermal blistering disease was previously shown to recognized a 450-kDa epidermal autoantigen. The molecular structure of this antigen was investigated by screening a human keratinocyte cDNA library with the patient's serum. One clone, with a 276-bp cDNA insert, that encoded an epitope recognized by the serum was isolated. Rabbit polyclonal antibodies that were prepared against the corresponding fusion protein recognized the 450-kDa epidermal antigen and stained the basal keratinocytes in human epidermis. This clone was used for further screening of the original keratinocyte and HeLa cell cDNA libraries. Two different, but closely related, 0.8- and 2.0-kb cDNAs were isolated, and their deduced amino acid sequences indicated that the encoded proteins belonged to the plectin family. Northern blot analysis of total RNA from human keratinocytes with these cDNA inserts as probes detected RNAs of approximately 12-13 kb. The 0.8-kb cDNA hybridized to polyadenylated RNA species from human skeletal muscle, heart, lung, and kidney, whereas the 2.0-kb cDNA hybridized to transcripts present only in kidney and lung. Southern blot analysis of genomic DNA from the human placenta revealed similar, but not identical, patterns of hybridization with the 0.8- and 2.0-kb cDNAs. Data suggest that the 0.8- and 2.0-kb cDNAs encode two different proteins but are derived from the same gene.

Subdural hemorrhage caused by de novo aneurysm complicating extracranial-intracranial bypass surgery: case report

A case of a de novo aneurysm leading to subdural hemorrhage after right extracranial-intracranial bypass surgery is described. After an uneventful 2-month postoperative course, the patient experienced sudden onset of occipital headache with vomiting. Radiological study disclosed an acute subdural hematoma in the right temporo-occipital region and a newly formed aneurysm at the site of patent superficial temporal artery-middle cerebral artery anastomosis. The anastomotic portion with the ruptured aneurysm was resected en bloc after alternative occipital artery-middle cerebral artery bypass, and the cut end of the superficial temporal artery was successfully used for end-to-side reanastomosis to the other middle cerebral artery branch. The histological examination of the ruptured aneurysm revealed the features of a true aneurysm.

Regulation of epidermal growth factor receptor by activated H-ras and V-myc oncogenes in mouse Balb/3T3 cells: possible roles of AP-1

We previously reported that introduction of H-ras oncogene decreases the epidermal growth factor (EGF) binding activity to cell surface EGF receptor in mouse Balb/3T3. In this study, we have further isolated four H-ras transfectants, four v-myc transfectants and three both H-ras and v-myc (H-ras/v-myc) transfectants of mouse Balb/3T3 cells. In comparison with introduction of v-myc alone or both H-ras and v-myc oncogene, introduction of H-ras alone resulted in a loss of [125I]EGF binding activity to the cell surface EGF receptor. RT-PCR analysis also showed much lower levels of EGF receptor gene expression in H-ras transfectants compared to that of parental untransformed cells (Balb-Neo1), v-myc and H-ras/v-myc transfectants. Our results demonstrated the activated binding of a transcription factor, Stat1 p84/p91, which directly interacts with EGF receptor, to c-sis-inducible element (SIE) in both v-myc and H-rs/v-myc transfectants, but not in H-ras transfectants. Among transcription factors which we have analysed, activator protein 1 (AP-1) but not SP-1 was modulated by H-ras. Gel shift assays demonstrated the mobility pattern of TPA-responsive element (TRE) binding complex with AP-1 derived from H-ras transfectants migrated faster than those from Balb-Neo1, v-myc and H-ras/v-myc. Expression of c-Jun and Fra-1 was increased more than threefold in H-ras transfectants compared with Balb-Neo1, v-myc and H-ras/v-myc transfectants, but that of c-Fos, Jun B and SP-1 was unchanged. Both transient and permanent expression of H-ras enhanced AP-1 activity in mouse cells, but further co-introduction of dominant negative c-jun mutant encoding a transcriptionally inactive product inhibited the H-ras dependent AP-1 induction. Transfection of the dominant negative c-jun mutant also restored down-regulation of EGF binding by activated H-ras oncogene. Down-regulation of EGf receptor by activated H-ras and the possible involvement of a transcription factor, AP-1 will be discussed.

Regulation of cytokine production by sugi allergen-pullulan conjugate

Sugi basic protein (SBP), a major allergen of Japanese cedar (Cryptomeria japonica) pollen, conjugated to pullulan (alpha-1,4'-, alpha-1,6'-glucan) reportedly suppresses IgE anti-SBP antibody production and enhances IgG anti-SBP antibody production in mice. We analyzed cytokine production by SBP-specific T cells after stimulation with an SBP-pullulan conjugate (SBP-P), native SBP, or a mixture of SBP and pullulan. When SBP-specific T cell lines were stimulated with the SBP-P conjugate in the presence of antigen-presenting cells (APC), the production of IFN-gamma, IL-4, IL-5, and IL-10 decreased compared with the cytokine levels produced by SBP-stimulated T cells. However, when these T cells were repeatedly stimulated with the SBP-P conjugate, the production of IFN-gamma increased progressively, while that of IL-4, IL-5, and IL-10 remained decreased compared with the T cells that were repeatedly stimulated with native SBP. Stimulation of the T cells with the mixture of SBP and pullulan showed little difference in the cytokine production profile from that observed after stimulation with native SBP alone. Interestingly, when the T cell lines stimulated repeatedly with SBP-P were subsequently stimulated with native SBP, a further increase in IFN-gamma production was observed, while IL-10 production decreased. Inhibition of IL-4 production was also observed when SBP-specific Th2 clones were stimulated with SBP-P. These results indicate that stimulation of T cells with SBP-P up-regulates Th1 cytokine production, while down-regulating that of Th2. It is, therefore, conceivable that immunotherapeutic treatment with the SBP-P conjugate rather than with conventional SBP solutions is preferable for improving Japanese cedar pollen allergy.

Heparin-binding epidermal growth factor-like growth factor: p91 activation induction of plasminogen activator/inhibitor, and tubular morphogenesis in human microvascular endothelial cells

Epidermal growth factor (EGF) or transforming growth factor-alpha (TGF-alpha) stimulates cell migration, proliferation and the formation of tube-like structures of human microvascular endothelial cells in culture. Heparin-binding EGF-like growth factor(HB-EGF), which shows 35% homology with EGF/TGF-alpha, is a member of the EGF family, and it is ubiquitous in many tissues and organs. We examined whether or not HB-EGF induced angiogenic responses in human microvascular endothelial cells. HB-EGF inhibited the binding of (125) I-EGF to the EGF receptor and induced autophosphorylation of the receptor on endothelial cells. Exogenous HB-EGF induced the loss of more than 70% of the EGF receptor from the cell surface within 30 min, with similar kinetics to that of EGF. The level of c-fos mRNA markedly increased at 30 min in response to HB-EGF as well as EGF. A gel shift assay demonstrated the activation of the transcription factor p91 by HB-EGF and EGF. This factor directly interacts with EGF receptor and mediates the activation of c-fos gene promoter. HB-EGF enhanced the mRNA expression of tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1) mRNA. However, the enhancement of t-PA and PAI-1 by HB-EGF was less than that by EGF. Heparitinase/chlorate, which digests the heparan sulfate proteoglycan of the endothelial cell surface, restored both t-PA and PAI-1 mRNA levels in response to HB-EGF in a manner similar to that by EGF. HB-EGF at 10 ng/ml developed tube-like structures in type I collagen gel at similar levels to that of EGF at 10 ng/ml, suggesting that HB-EGF is also a potent angiogenic factor in the model system for angiogenesis. The tubulogenesis activity of HB-EGF is discussed in relation to the expression of the t-PA and PAI-1 genes.

[The evaluation of the bio-compatibility and the clinical usefulness of heparin-coated cardiopulmonary bypass circuits]

We studied the biocompatibility and the clinical usefulness of heparin-coated cardiopulmonary bypass circuits (Duraflow-II) compared with non-coated circuits. First study was done to clarify the biocompatibility of heparin coated circuit. 33 cases of elective coronary artery bypass grafting were randomized into two grops. Both group had full dose heparin in this study and laboratory tests were done such as blood cell count, free hemoglobin, AT-III, fibrinogen, FDP, and complement system. The use of heparin-coated circuits resulted in a reduction of C3a generation, and a reduction of fibrinogen consumption. The decline of AT-III may be due to bonding of coated heparin to AT-III, leading to effective anticoagulation. Next study was carried out in 26 cases. In heparin coated group, the amount of heparin was reduced to 200 IU/kg compared to 350 IU/kg in control group. ACT was maintained above 300 sec. and 400 sec. respectively. The amount of post operative bleeding was identical in both groups. There was no case which required autologous blood transfusion, re-operation for bleeding in both groups. Myocardial infarction and hospital mortality were not seen in this study. Concerning the fear of graft occlusion in low dose heparin surgery, there was no statistical difference of graft patency in both groups. In conclusion, heparin coated CPB circuits (Duraflo-II) are favorable in the meaning of biocompatibility and sefely used with low dose heparin.

Renal denervation prevents intraglomerular platelet aggregation and glomerular injury induced by chronic inhibition of nitric oxide synthesis

Nitric oxide (NO) inhibits platelet adhesion and aggregation in vitro. In vivo, chronic inhibition of NO synthesis induces nephrosclerosis and hypertension. Although the pathophysiological mechanism of this glomerular injury has not been clarified, sympathetic nerve activation, a potent procoagulant stimulus elicited by NO inhibition, may play a role. To investigate the role of renal sympathetic nerves in the development of renal injury induced by NG-nitro-L-arginine methyl ester (L-NAME), a specific NO synthesis inhibitor, we examined renal histological changes in four groups of Sprague-Dawley rats: (1) sham operated, vehicle treated; (2) sham operated, L-NAME treated; (3) denervated, vehicle treated, and (4) denervated, L-NAME treated. Following renal denervation or sham operation, L-NAME was administered orally for 4 weeks. Chronic NO inhibition induced platelet aggregation and erythrocyte stasis in the glomerular capillary lumen accompanied by electron-microscopic glomerular injury. Renal denervation abrogated platelet aggregation and glomerular injury in L-NAME-treated animals. Thus, chronic NO synthesis inhibition induced intraglomerular platelet aggregation and glomerular injury, which was attenuated by renal nerve denervation. These results suggest that intrinsic NO may have an antithrombotic effect in the glomeruli and may play a protective role in the progression of glomerular injury possibly mediated by renal sympathetic nerves.

Chronic L-arginine administration attenuates cardiac hypertrophy in spontaneously hypertensive rats

Nitric oxide inhibits proliferation and migration of vascular smooth muscle cells and contractility of cardiomyocytes in vitro. In spontaneously hypertensive rats (SHR), evidence suggests intrinsic abnormalities of the L-arginine-nitric oxide axis, such as low cGMP-dependent protein kinase in the heart and abnormal L-arginine metabolism. To investigate the in vivo effect of L-arginine on cardiac hypertrophy, 30 SHR and 30 Wistar-Kyoto rats (WKY) were randomly grouped to receive L-arginine (7.5 g/L in drinking water) or vehicle for 12 weeks. L-Arginine treatment did not affect body weight or arterial pressure in either strain. In vehicle-treated animals, the heart/body weight ratio was significantly higher in SHR than in WKY (P < .01). L-Arginine treatment decreased the heart/body weight ratio in SHR (P < .05) but did not affect it in WKY. Expression of skeletal alpha-actin mRNA, known to be expressed in the hypertrophied myocardium, was attenuated in L-arginine-treated SHR compared with vehicle-treated SHR. Cardiac cGMP content and nitrate/nitrite content were less in SHR than WKY. L-Arginine treatment increased these levels only in SHR, suggesting enhanced nitric oxide production. Thus, chronic L-arginine administration attenuated cardiac hypertrophy independently of blood pressure and increased myocardial content of cGMP and nitrate/nitrite. Our results suggest that abnormality of the cardiac L-arginine-nitric oxide axis may play an important role in the pathogenesis of cardiac hypertrophy in SHR.

Localization of ZNF164, ZNF146, GGTA1, SOX2, PRLR and EEF2 on homoeologous cattle, sheep and goat chromosomes by fluorescent in situ hybridization and comparison with the human gene map

The six following genes: zinc finger proteins 164 (ZNF164) and 146 (ZNF146), alpha-galactosyltransferase 1 (GGTA1), SRY-related HMG-box 2 (SOX2), prolactin receptor (PRLR) and elongatin factor 2 (EEF2) have been localized by fluorescent in situ hybridization respectively on bovine and caprine chromosomes 17, 18, 11, 1, 20 and 7 and on sheep chromosomes 17, 14, 3, 1, 16, and 5. The comparison of the results with the localization of these genes in man (except for ZNF164) confirm the correspondences between human and bovine chromosomes established from heterologous chromosome painting data.

The exogenous control of transfected c-fos gene expression and angiogenesis in cells implanted into the rat brain

Previously, we established a stable transfectant, Nf-1, from normal rat kidney (NRK) fibroblasts transfected with a human metallothionein II A (hMT-IIA) promoter/human genomic c-fos fusion gene to produce c-Fos protein. Since the hMT-IIA promoter can be activated by heavy metals, the level of human c-fos gene expression can be increased by addition of heavy metals to the culture medium of Nf-1 cells and the anchorage-independent growth of Nf-1 in soft agar is markedly enhanced in the presence of transforming growth factor-beta (TGF-beta) and epidermal growth factor (EGF). In this study, we found that the hMT-IIA promoter can be activated by zinc, resulting in the elevation of fused c-fos gene expression in Nf-1 cells. We transplanted NRK and Nf-1 cells into the striatum of the rat brain and investigated whether expression of the human c-fos gene could be modified in the brain by exogenous zinc. After 8 weeks, we found that the Nf-1 cells could survive in the rat brain without any immunosuppression and grafts of Nf-1 induced angiogenesis when zinc was administered. Such implants enhanced the expression of c-fos mRNA by zinc. These results indicated that the transplanted cells continued expressing the c-fos transgene when the rats were given drinking water containing zinc, resulting in the promotion of cell growth and of neovascularization. This study will present a useful animal model of gene therapy by control of transgene expression in the brain.

Changes of relaxation times (T1, T2) and apparent diffusion coefficient after permanent middle cerebral artery occlusion in the rat: temporal evolution, regional extent, and comparison with histology

The quantitative NMR parameters T1, T2, rho, and apparent diffusion coefficient (ADC) were determined during the 7 h after middle cerebral artery occlusion in rats. In the normal caudate-putamen (CP), 869 +/- 145 ms and 72 +/- 2 ms for T1 and for T2, respectively, were found; the corresponding values for cortex were 928 +/- 117 ms and 73 +/- 2 ms. The ADC showed significant dependence on gradient direction: diffusion along x resulted in 534 +/- 53 microns 2/s (CP) and 554 +/- 62 microns 2/s (cortex), and along y in 697 +/- 58 microns 2/s (CP) and 675 +/- 53 microns 2/s (cortex). In the ischemic territory, a continuous increase over time of both relaxation times was observed in the CP, leading to an increase of 29 +/- 20% (T1) and 51 +/- 41% (T2) above control level. ADC dropped to 63 +/- 15% of control in the CP and to 74 +/- 4% of control in the temporal cortex. No significant change was noted in proton density during the observation period. Strongest ADC reduction was in the center of the ischemic territory (< or = 60% of control) surrounded by a region of lesser reduction (< or = 80% of control). During the early part of the study, the area of reduced ADC was larger than that of elevated relaxation times. Toward the end of the experiment, the area of increased relaxation times approached that of decreased ADC at < or = 80% of control. Good agreement of histological presentation of infarct with the total area of decreased ADC (< or = 80%) was demonstrated.

[MRI of the pituitary adenomas with reference to the hormonal activity]

Many studies in Magnetic Resonance Imaging (MRI) of pituitary adenomas are already performed. However, few reports exist about MRI findings of pituitary adenomas with reference to the hormonal activity, therefore, we evaluated this problem on the viewpoint of the signal intensity in MRI and pathological features. Fifteen patients with growth hormone producing adenoma (GH-group), 6 patients with prolactin producing adenoma (PRL-group), 15 patients with endocrinologically non-functioning adenoma (Null-group) and 9 cases with normal pituitary gland (normal control group) were examined. Signal intensity values in adenoma (or anterior lobe in normal control group) and in pons as standard value were measured in each cases, then their rates were calculated as signal intensity ratio (SIR). In 24 cases (14 in GH-group, 3 in PRL-group, 7 in Null-group), cellular density were examined with surgically resected specimens. In the T1-weighted images (T1 WIs), PRL-group and Null-group presented more hypointense tendency than normal control group. In the T2-weighted images (T2 WIs), only Null-group presented more hyperintense tendency than other groups. But significant correlation was not observed between SIR and cellular density.

Comparison of axonemal proteins from two kinds of Tetrahymena. I. Different characteristics of dyneins in heat stability

Tetrahymena thermophila could still swim after incubation of the cell body at 40 degrees C for 30 min, whereas Tetrahymena pyriformis did not show any motility after the treatment. Turbidity measurements revealed that axonemes of T. pyriformis lost ATP-dependent sliding activity by the heat treatment, whereas those of T. thermophilia still had the activity under the same conditions. In connection with this difference in susceptibility to high temperature, the biochemical characteristics of dyneins were compared between the two species of Tetrahymena. Axonemal dyneins from the two species had significant vanadate-sensitive ATPase activity even after the heat treatment. Native gel electrophoresis and the following two-dimensional electrophoresis showed that the outer arm dynein of T. thermophilia is more stable in maintaining native configuration than that of T. pyriformis against the heat treatment, although both treated dyneins keep three (alpha, beta and gamma) subunits. Analysis by peptide mapping demonstrated that beta- and gamma-subunits of the outer arm dynein are considerably different in amino acid sequences between the two species. These results imply that dynein of T. thermophilia changed their amino acid sequences and biochemical characteristics to adapt to high temperature.

Early detection of cerebral ischemic lesion using diffusion-weighted MRI

We performed serial diffusion-weighted imaging (DWI) in a patient with right middle cerebral arterial occlusion using 1.0 T MRI. The initial DWI demonstrated suppression of water diffusion in the gray matter in the ischemic lesion as a high signal area 4 h after stroke onset, when T2-weighted imaging failed to detect any parenchymal injury. Repeat DWI 9 h after onset demonstrated the whole infarct, whereas it was not demonstrated by T2-weighted imaging until 48 h. Furthermore, the regional apparent diffusion coefficient (ADC) had already decreased significantly in both the gray and white matters of the ischemic lesion 4 h after onset, even though hyperintensity was not visible in the white matter on the DWI. The features in this case indicate that DWI in conjunction with the assessment of regional ADC can provide important information regarding the evolving infarct at a very early stage even when a relatively low tesla clinically available MRI unit is used.

Biomodulation by hyperthermia of topoisomerase II-targeting drugs in human colorectal cancer cells

We examined whether heat stress could enhance the sensitivity of human colon cancer WiDr cells to topoisomerase II-targeting anticancer agents, etoposide (VP-16) and teniposide (VM-26), and also determined the most effective timing for the drug administration after exposure to hyperthermia. Both topoisomerase II contents and topoisomerase II activity were significantly increased in WiDr cells 3 to 12 h after heat stress at 43 degrees C for 1 h, in comparison with those immediately after the heat stress. Cytotoxicity by VP-16 was most significantly enhanced 3 to 12 h after exposure to 43 degrees C for 1 h, but no synergistic effect was observed when the drug was administered immediately after the heat stress. A combination of VM-26 with heat stress, but not that of a topoisomerase I-targeting camptothecin derivative (CPT-11), or vincristine, showed a synergistic cytotoxic effect on WiDr cells. VP-16 alone induced cellular accumulation at the G2 + M phase, whereas the combination of VP-16 and heat stress further increased the cell population at the G2 + M phase, and decreased S-phase cells. A possible application of the combination of VP-16 and hyperthermia in clinical use is discussed.

Oxytocinergic innervation to the upper thoracic sympathetic preganglionic neurons in the rat. A light and electron microscopical study using a combined retrograde transport and immunocytochemical technique

A combination of retrograde cell body labeling and immunohistochemistry was employed to elucidate how oxytocinergic fibers make contact with sympathetic preganglionic neurons (SPNs) in the rat spinal cord from T1 to T4. SPNs were labeled retrogradely using cholera toxin subunit B (CTb) or horseradish peroxidase-conjugated CTb. Oxytocin-immunoreactive (ir) fibers were found in the intermediate zone, including the sympathetic preganglionic subnuclei. In the central autonomic nucleus and the intercalated nucleus, brown-stained oxytocin-ir varicosities or terminals were frequently observed to stud black-stained dendrites of SPNs. Electron microscopical observations showed that oxytocin-ir terminals form synapses with dendrites or soma of the sympathetic preganglionic neurons. The terminals contained numerous small clear round vesicles and a few large, cored vesicles. These results clearly show that a large proportion of SPNs are innervated by oxytocin-containing fibers. The origin of these fibers is discussed, and it is concluded that they are probably descending fibers from the paraventricular nucleus of the hypothalamus.

Evolution of regional changes in apparent diffusion coefficient during focal ischemia of rat brain: the relationship of quantitative diffusion NMR imaging to reduction in cerebral blood flow and metabolic disturbances

Middle cerebral artery occlusion was performed in rats while the animals were inside the nuclear magnetic resonance (NMR) tomograph. Successful occlusion was confirmed by the collapse of amplitude on an electrocorticogram. The ultrafast NMR imaging technique UFLARE was used to measure the apparent diffusion coefficient (ADC) immediately after the induction of cerebral ischemia. ADC values of normal cortex and caudate-putamen were 726 +/- 22 x 10(-6) mm2/s and 659 +/- 17 x 10(-6) mm2/s, respectively. Within minutes of occlusion, a large territory with reduced ADC became visible in the ipsilateral hemisphere. Over the 2 h observation period, this area grew continuously. Quantitative analysis of the ADC reduction in this region showed a gradual ADC decrease from the periphery to the core, the lowest ADC value amounting to about 60% of control. Two hours after the onset of occlusion, the regional distribution of ATP and tissue pH were determined with bioluminescence and fluorescence techniques, respectively. There was a depletion of ATP in the core of the ischemic territory (32 +/- 20% of the hemisphere) and an area of tissue acidosis (57 +/- 19% of the hemisphere) spreading beyond that of ATP depletion. Regional CBF (rCBF) was measured autoradiographically with the iodo[14C]antipyrine method. CBF gradually decreased from the periphery to the ischemic core, where it declined to values as low as 5 ml 100 g-1. When reductions in CBF and in ADC were matched to the corresponding areas of energy breakdown and of tissue acidosis, the region of energy depletion corresponded to a threshold in rCBF of 18 +/- 14 ml 100 g-1 min-1 and to an ADC reduction to 77 +/- 3% of control. Tissue acidosis corresponded to a flow value below 31 +/- 11 ml 100 g-1 min-1 and to an ADC value below 90 +/- 4% of control. Thus, the quantification of ADC in the ischemic territory allows the distinction between a core region with total breakdown of energy metabolism and a corona with normal energy balance but severe tissue acidosis.

Intraventricular administration of nitric oxide synthase inhibitors prevents delayed neuronal death in gerbil hippocampal CA1 neurons

We performed experiments to investigate the participation of nitric oxide (NO) in the delayed neuronal death (DND) of gerbil hippocampal CA1 neurons, following 5-min forebrain ischemia with pretreatment of stereotaxic intraventricular administration of several types of NO synthase inhibitors and biologically inactive control drugs. The number of surviving neurons in the control drug groups administered NG-monomethyl-D-arginine or NG-nitro-D-arginine methyl ester was comparable to that in the group administered artificial cerebro-spinal fluid, while the groups administered NOS inhibitors, such as NG-monomethyl-L-arginine or NG-nitro-L-arginine methyl ester, showed significant preservation of the neuronal densities compared with the control drug groups, to over 60% of the sham operation group value. Furthermore, intraventricular administration of N omega-nitro-L-arginine at various concentrations disclosed a dose-dependent protection against the DND. These results suggest that the generation of NO may act to promote the establishment of DND.

[Serum cardiac troponin-T in coronary artery bypass graft and mitral valve replacement]

Serum cardiac troponin-T was measured to evaluate perioperative myocardial injury in heart surgery. Twelve patients of coronary artery bypass graft (CABG) and nine of mitral valve replacement (MVR) were selected and the measurements were performed at 3 points-before, as well as after the surgery and on the first postoperative day. Elevated serum levels of troponin-T were observed in postoperative measurement in both groups (CABG 2.98 +/- 1.44, MVR 2.57 +/- 0.52 ng.ml-1), where all the preoperative values were less than 0.1 ng.ml-1. On the first postoperative day, CABG group showed a higher serum level of troponin-T than MVR group (6.05 +/- 4.16 vs. 2.57 +/- 2.12 ng.ml-1, P < 0.05 respectively). Taking another myocardial marker, such as CK-MB or myosin light chain I, into consideration, these data indicate that myocardial injury occurs during heart surgery and the grade of injury is severer in CABG than in MVR.

[A study of preventive medicine in relation to mental health among middle-management employees (Part 2)--effects of long working hours on lifestyles, perceived stress and working-life satisfaction among white-collar middle-management employees]

Recently, we have introduced the holistic method into health care of workers and aimed at improvement of Quality of Life (QOL). It has been made clear that primary prevention of diseases needs lifestyle appraisal. Therefore, we studied the daily working hours and the effects of long working hours on lifestyles, perceived stress and working-life satisfaction, which we used as a subjective index of Quality of Life (QOL), based on data obtained from a survey of 1,026 department chiefs and 2,902 section chiefs in 110 large companies in Japan in 1990. The results are summarized as follows. (1) The percentage of those working 10 hours per day was 41.6% for department chiefs and 40.4% for section chiefs, and for 11 or more working hours it was 24.1% in department chiefs and 30.9% in section chiefs. The younger both department and section chiefs, the longer their working hours. (2) Both department and section chiefs had a significant relationship between long working hours and poor sleeping habits, poor physical exercise, feeling busy, irregularity of daily life and irregularity of daily meals. The department chiefs had a significant relationship between long working hours and unbalanced nutrition or no hobbies. The section chiefs had a significant relationship between long working hours and drinking many cups of tea or coffee, taking a lot of salt or ill physical condition during the past six months.

Cellular levels of thioredoxin associated with drug sensitivity to cisplatin, mitomycin C, doxorubicin, and etoposide

Thioredoxin, a cellular thiol, functions as a self-defense mechanism in response to environmental stimuli, including oxidative stress. We first determined cellular levels of thioredoxin in several human bladder and prostatic cancer cell lines resistant to cis-diamminedichloroplatinum(II) (cisplatin). All cisplatin-resistant cell lines had much higher levels of thioredoxin than those in their drug-sensitive parental counterpart. We then, by introducing thioredoxin antisense expression plasmids into human bladder cancer T24 cells, established two bladder cancer cell lines that had decreased levels of thioredoxin. These thioredoxin antisense transfectants showed increased sensitivity to cisplatin and also to other superoxide-generating agents, i.e., doxorubicin, mitomycin C, etoposide, and hydrogen peroxide, as well as to UV irradiation, but not to the tubulin-targeting agents, vincristine, and colchicine. Cellular levels of thioredoxin thus appear to limit sensitivity to various superoxide-generating anticancer drugs in cancer cells.