Erythropoietin induces tyrosine phosphorylation of Jak2, STAT5A, and STAT5B in primary cultured human erythroid precursors

We examined signaling by erythropoietin in highly purified human colony forming unit-erythroid cells, generated in vitro from CD34(+) cells. We found that erythropoietin induces tyrosine phosphorylation of Jak2, STAT5A, and STAT5B. Tyrosine phosphorylation of Jak2 reaches a peak around 10 minutes after stimulation and is maximum at 5 U/mL of erythropoietin. Tyrosine phosphorylation of STAT5 is accompanied by the translocation of activated STAT5 to the nucleus as shown by electrophoretic mobility shift assay (EMSA) using 32Pi-labeled STAT5 binding site in the beta-casein promoter. Tyrosine phosphorylation STAT1 or STAT3 was not detected in human erythroid precursors after stimulation with erythropoietin. Crkl, an SH2/SH3 adapter protein, becomes coimmunoprecipitated specifically with STAT5 from erythropoietin-stimulated erythroid cells; although it was shown to become associated with c-Cbl in the studies using cell lines. Thus, human erythroid precursors can be expanded in vitro in sufficient numbers and purity to allow its usage in signal transduction studies. This report sets a basis for further studies on signaling in primary cultured human erythroid precursors, which in turn contribute to our better understanding in the differentiation processes of erythrocytes and their precursors.

Nitric oxide donors induce late preconditioning against myocardial stunning and infarction in conscious rabbits via an antioxidant-sensitive mechanism

The goal of this study was to test the hypothesis that the cardioprotective effects of the late phase of ischemic preconditioning (PC) can be mimicked by treatment with NO donors. In phase I (studies of myocardial stunning), conscious rabbits underwent a sequence of six 4-minute coronary occlusion/4-minute reperfusion cycles for 3 consecutive days (days 1, 2, and 3). In group I (controls, n=6), the total deficit of systolic wall thickening (WTh) after the sixth reperfusion was reduced by 54% on days 2 and 3 compared with day 1 (P<0.05), indicating a late PC effect against myocardial stunning. When rabbits were given the NO donors diethylenetriamine/NO (DETA/NO, 0.1 mg/kg i.v., 4 times [group II, n=5]) or S-nitroso-N-acetylpenicillamine (SNAP, 2.5 microg x kg(-1) x min(-1) i.v. for 75 minutes [group III, n=51) 24 hours before the first sequence of occlusion/reperfusion cycles, the deficit of WTh on day 1 was 60% (group II) and 54% (group III) less than that observed in controls (P<0.05 for both). In both groups II and III, there was no further improvement in the deficit of WTh on days 2 and 3 compared with day 1. The protective effect of DETA/NO was completely abrogated when this agent was given in conjunction with the ONOO- and .OH scavenger mercaptopropionyl glycine (MPG) (group IV, n=5). In phase II (studies of myocardial infarction), conscious rabbits underwent a 30-minute coronary occlusion followed by 3 days of reperfusion. When rabbits were preconditioned 24 hours earlier with six 4-minute occlusion/4-minute reperfusion cycles, infarct size was reduced by 43% (33.2+/-2.7% versus 58.3+/-4.1% of the region at risk in controls, P<0.05), indicating a late PC effect against myocardial infarction. When rabbits were pretreated with DETA/NO (group VII, n=8) or SNAP (group IX, n=7) 24 hours before the 30-minute occlusion, infarct size was reduced by a similar degree (29.3+/-3.6% and 32.0+/-3.3% of the region at risk, respectively; P<0.05 versus controls). The degree of protection could not be increased by doubling the dose of DETA/NO (group VIII, n=5). Coadministration of MPG completely abrogated the infarct-sparing action of DETA/NO (group X, n=7). Taken together, these results demonstrate that in conscious rabbits the administration of 2 structurally unrelated NO donors induces protection 24 hours later against both reversible (stunning) and irreversible (infarction) ischemia/reperfusion injury and that the magnitude of this protection is indistinguishable from that observed during the late phase of ischemic PC. The fact that the late phase of ischemic PC can be mimicked by NO donors provides direct evidence that NO in itself is sufficient to elicit this cardioprotective mechanism. The fact that NO donor-induced late PC was abrogated by MPG indicates that the mechanism whereby NO induces this phenomenon involves the generation of oxidant species, possibly ONOO- and/or .OH. Since a relatively brief treatment with hemodynamically inactive doses of NO donors can induce long-lasting protective effects, these agents could be useful for preconditioning the heart in patients.

Hemodynamics of a simulation of the vertebrobasilar system using silicone tube

We investigated the hemodynamics of the vertebrobasilar system (VBS) using a simulation model tube made of silicone which had different diameters between the bilateral vertebral artery (VA) ducts (stenotic and normal VA ducts). Using the ultrasonic Doppler method. the laterality index (L.I.) of the flow velocity in the VA duct was 32.88%. The flow volume of the anterior inferior cerebellar artery duct and the posterior inferior cerebellar artery duct also had significant laterality. By investigating the effects of the rotatory pulse rate and fluid viscosity, a maximal decrease to below 40-50% of the flow volume of the branches, and to below 71.93% in the mean flow velocity of the basilar artery (BA) duct (BA duct) were observed. and the maximum L.I. increased to 43.15%. When the unilateral stenotic VA duct was occluded by clamping (clamping occlusion), the flow volume profiles of the branches were the same as without clamping occlusion. The L.I. showed no significant changes and the maximal decrease in the mean flow velocity of the BA duct was 68.61%. Using the laser Doppler method, the flow velocity distribution of the BA duct was shifted towards the side of the stenotic VA duct. These results suggest that the rheological dynamics in the main vessels can certainly reflect the posterior circulatory dynamics, and that modulating factors also aggravate the hemodynamics of the VBS with this disorder.

Long-term exposure to diesel exhaust enhances antigen-induced eosinophilic inflammation and epithelial damage in the murine airway

The histopathologic changes in the murine airway induced by long-term exposure to diesel exhaust (DE), ovalbumin (OA), or both were investigated. The relationship between the histopathologic appearances in the airway and immunoglobulin production or local cytokine levels in the lungs was also studied. ICR mice were exposed to clean air or DE at a soot concentrations of 0.3, 1.0, or 3.0 mg/m3 for 34 weeks. Fifteen weeks after exposure to DE, mice were sensitized intraperitoneally with 10 micrograms of OA and challenged by an aerosol of 1% OA six times at 3-week intervals during the last 18 weeks of the exposure. DE exposure caused a dose-dependent increase of nonciliated cell proliferation and epithelial cell hypertrophy in the airway, but showed no effect on goblet cell proliferation in the bronchial epithelium and eosinophil recruitment in the submucosa of the airway. OA treatment induced very slight changes in goblet cell proliferation and eosinophil recruitment. The combination of OA and DE exposure produced dose-dependent increases of goblet cells and eosinophils, in addition to further increases of the typical changes induced by DE. OA treatment induced OA-specific IgG1 and IgE production in plasma, whereas the adjuvant effects of DE exposure on immunoglobulin production were not observed. Inhalation of DE led to increased levels of IL-5 protein in the lung at a soot concentration of 1.0 and 3.0 mg/m3 with OA, although these increases did not reach statistical significance. We conclude that the combination of antigen and chronic exposure to DE produces increased eosinophilic inflammation, and cell damage to the epithelium may depend on the degree of eosinophilic inflammation in the airway.

[Incidence of mutation and deletion in topoisomerase II mRNA of etoposide and m-AMSA resistant cell lines]

The efficacy of all chemotherapeutic agents is limited by the occurrence of drug resistance. To further understand resistance to topoisomerase (topo) II inhibitors, 50 sublines were isolated as single clones from parental cells by exposure to ETP or m-AMSA. Subsequently, a population of cells from each subline was exposed to three-fold higher drug concentrations allowing 16 stable sublines to be established at higher extracellular drug concentration. The frequency and nature of mutations in topo II in the drug selected cell lines have been evaluated. In order to screen a large number of cell lines, an RNase protection assay was developed. Fragments covering the entire coding sequence of topo II was isolated after PCR amplification and subcloned in pGEM3Z vector. Using this approach, mismatches was observed in 13.6% of resistant cell lines (12% of resistant cell lines exposed to lower drug concentrations and 18.8% of resistant cell lines exposed to higher drug concentrations). Our findings suggest that mutations of topo II gene seem to be an important and frequent mechanism of resistance to topo II inhibitors.

Long-term results of corticosteroid administration via appendicostomy in patients with ulcerative colitis involving the entire colon

BACKGROUND

Ulcerative colitis (UC) of an unknown etiology frequently demonstrates repeated active and inactive stages. As a result, it is difficult to sustain long-term remission under conservative therapy.

METHODS

Ten patients who presented suffering from UC involving the entire colon were treated. All patients had been previously treated at other hospitals usually with sulphasalazine and either corticosteroids or steroid enemas for the primary complaints of muco-bloody stool or frequent diarrhea. All patients underwent either an appendicostomy or cecostomy, and were injected with dexamethasone via an artificial fistula twice a day.

RESULTS

This treatment led to remission, and, as a result, the symptoms of anal bleeding or muco-bloody stools disappeared in all patients. Radiological, endoscopic, and pathological studies revealed a dramatic response to steroid injection from the fistula. The mean follow-up period was 44.7 months (3-122 months). Eight patients remained free from any symptoms of UC. One underwent a proctocolectomy because of side effects due to steroid treatment. The other patient died suddenly of unknown causes. The mean symptom-free period after cecal injection was 39.5 months (1-119 months). The mean proportion of disease free period from UC, compared with the total follow-up period after surgery, was 88%. After remission, eight patients were able to return to a normal lifestyle at home using a peritoneal button. They could also take a bath and continue their school or social lives in almost the same way as healthy persons.

CONCLUSIONS

We thus recommend this new, minimally-invasive therapy for patients with UC involving the entire colon who demonstrate resistance to conventional conservative therapy. As a result of such treatment, all patients were able to achieve a comfortable lifestyle after undergoing minimally-invasive surgery.

Cervical spine abnormalities and instability with myelopathy in warfarin-related chondrodysplasia: 17-year follow-up

A patient with warfarin embryopathy developed progressive cervical spinal myelopathy owing to bony cervical spinal damage. While there are several descriptions of warfarin embryopathy, the long-term complication of cervical spinal instability has not been reported. This cervical instability may, as in our patient, cause severe neurological dysfunction or even sudden death; therefore, it is important that pediatric radiologists should be alert to this condition.

Alteration of the properties of gastric smooth muscle in the genetically hyperglycemic OLETF rat

Membrane responses were recorded from isolated gastric smooth muscle of Otsuka Long-Evans Tokushima Fatty (OLETF) and Long-Evans Tokushima Otsuka (LETO) rats, using microelectrode techniques. At the age of 68-76 weeks, the blood sugar level was 181 mg/dl in LETO rats and 350 mg/dL in OLETF rats. In both rats, the membrane potential was stable in fundus muscle and spontaneously active with generation of slow waves in antrum muscle. The resting membrane potential was about - 46 mV in fundus and - 55 mV in antrum muscles of LETO rats, and the values were 3-7 mV lower in OLETF rats. The slow waves were generated regularly in LETO rats, while they were irregular and of small amplitude in OLETF rats. Transmural nerve stimulation evoked a cholinergic excitatory junction potential and following inhibitory junction potential in LETO rats, and only an inhibitory junction potential of smaller size was generated in most of OLETF rats. The acetylcholine-induced depolarization was greater in OLETF than in LETO rats. The level of hyperpolarization produced by noradrenaline was similar between OLETF and LETO rats. Thus, the reduction of the resting membrane potential, weakening of spontaneous activity, impairment of cholinergic transmission and cholinergic supersensitivity were associated with hyperglycemia. These alterations were considered due to the development of diabetes mellitus.

Development of a flow estimation and control system of an implantable centrifugal blood pump for circulatory assist

A bypass flow rate estimation and control system (BECS) for an implantable centrifugal blood pump (ICBP) has been developed in our institute. The estimated flow rate (EF) of the ICBP was derived from the electric power consumption, the rotating speed of a motor, and the blood viscosity presumed by the hematocrit and body temperature. The error in the EF was 0.5 +/- 0.4 L/min in in vivo experiments for 40 days. The rotating speed of the motor was controlled automatically every 200 ms to bring the EF in accord with the desired flow rate (DF). The reactivity and accuracy of the BECS were investigated in in vitro and in vivo experiments. The ICBP was operated by the BECS in a mock circuit in parallel with a pulsatile ventricular assist device (PVAD) to simulate left heart bypass. The reactivity was evaluated by changing the DF from 7 L/min to 5 L/min at an afterload of 160/97 mm Hg. To evaluate the accuracy of the BECS, the ICBP was driven under the aortic pressure of 110/85 mm Hg in the abdominal wall of an adult goat (70 kg). The DF was set at 5 L/min for 4 min for the goat in an awake condition. It took 13 s to change the flow rate in the in vitro experiment. The measured flow rate (MF) was maintained at 5.0 +/- 0.2 L/min by the BECS in vivo. In conclusion, the BECS has moderate reactivity and accuracy.

Diesel exhaust inhalation enhances airway hyperresponsiveness in mice

BACKGROUND

Repeated intratracheal instillation of diesel exhaust particles and ovalbumin-induced airway hyperresponsiveness and airway inflammation in mice. However, the effects of daily inhalation of diesel exhaust may differ from the effects of direct instillation.

METHODS

Therefore, mice were exposed to diesel exhaust by inhalation 12 h per day for 3 months. Before the diesel exhaust exposure, ovalbumin was injected intraperitoneally as a sensitization. After 3 weeks of diesel exhaust exposure, these mice were challenged with ovalbumin every 3 week thereafter.

RESULTS

Diesel exhaust exposure with antigen challenge induced airway hyperresponsiveness and airway inflammation which was characterized by increased numbers of eosinophils and mast cells in lung tissue. The recruitment of inflammatory cells was accompanied by an increment in goblet cells on bronchial epithelium. Diesel exhaust exposure alone also enhanced airway hyperresponsiveness, but did not induce eosinophilic infiltration and/or an increment in goblet cells.

CONCLUSION

Diesel exhaust inhalation enhanced airway hyperresponsiveness and airway inflammation caused by ovalbumin sensitization in mice.

Inhalation of diesel exhaust enhances allergen-related eosinophil recruitment and airway hyperresponsiveness in mice

We have previously shown that intratracheal instillation of suspension of diesel exhaust particles enhances allergen-related eosinophilic airway inflammation, airway hyperresponsiveness, and local expression of interleukin (IL)-5 and granulocyte macrophage-colony stimulating factor (GM-CSF) in mice. The present study was designed to elucidate the effects of daily inhalation of diesel exhaust (DE) on the allergen-related respiratory disease. ICR mice were exposed for 40 weeks to clean air or DE at a soot concentration of 0.3, 1.0, or 3.0 mg/m3 with aerosol allergen challenges (1% ovalbumin in isotonic saline for 6 min) at 3-week intervals during the last 24 weeks of exposures. Exposure to DE enhanced allergen-related eosinophil recruitment to the submucosal layers of the airways and to the bronchoalveolar space, and increased protein levels of GM-CSF and IL-5 in the lung in a dose-dependent manner compared to exposure to clean air. There were strong correlations between the number of eosinophils in bronchoalveolar lavage (BAL) fluid and IL-5 concentrations in BAL supernatants and lung tissue supernatants. In addition, the increases in eosinophil recruitment and local cytokine expression were accompanied by goblet cell proliferation in the bronchial epithelium and airway hyperresponsiveness to inhaled acetylcholine. In contrast, the control mice exposed for 40 weeks to clean air or DE at a soot concentration of 0.3, 1.0, or 3.0 mg/m3 without allergen provocation showed no eosinophil recruitment to the submucosal layers of the airways nor to the bronchoalveolar space and few goblet cells in the bronchial epithelium. The present study provides experimental evidence that daily inhalation of DE can enhance allergen-related respiratory diseases such as allergic asthma. This effect may be mediated by the enhanced local expression of IL-5 and GM-CSF. Increased ambient levels of DE may be implicated in the increasing prevalence of bronchial asthma in recent years.

Intrathoracic and intraabdominal wall implantation of a centrifugal blood pump for circulatory assist

An implantable centrifugal pump (ICP) 320 ml in volume and 830 g in weight has been developed for prolonged circulatory assist. The antithrombogenicity of the ICP is provided by a balancing hole in the center of the impeller. The watertightness and histocompatibility of the ICP are supported by its silicone ring seal and its casing of titanium and acrylic resin, respectively. The total efficiency of the ICP was 30% at a 5 L/min flow rate and a 100 mm Hg head. The heat generation, watertightness, and anatomical fitting of the ICP were assessed in an intrathoracic implantation in a goat (66 kg) and in an intraabdominal wall implantation in a goat (70 kg). Warfarin was given for anticoagulation in each experiment to keep the prothrombin time around 1.7 times that of the control. The temperatures of the pump surface, the pleura, and the room were measured every 3 h. Anatomical fitting was evaluated by pathological observation after the termination of the experiment. The ICP could run for 40 days in the chest cavity and for 11 days in the abdominal wall. The temperature of the motor remained about 1.8 degrees C higher than the reference in both experiments. The ICP was completely covered by a layer of smooth fibrous tissue. The moisture content of the seals remained normal. Although a small amount of atelectasis was found in the lingula, neither lung adhesion nor necrotic change of the chest wall was observed. The inflammation of the surrounding tissue including foreign body reaction and thermal burn was minimal. In conclusion, the ICP has satisfied in vivo testing of its watertightness, exothermicity, and anatomical fitting.

Characterization of a chloroplast isoform of serine acetyltransferase from the thermo-acidiphilic red alga Cyanidioschyzon merolae

We isolated a gene for serine acetyltransferase (SAT), a key enzyme in sulfate assimilation, from the primitive red alga Cyanidioschyzon merolae, an inhabitant of sulfurous hot springs, and designated this gene cmSAT. The N-terminal region of the cmSAT protein has characteristics of a chloroplast targeting peptide. cmSAT protein fused with a 6x histidine tag complemented a SAT deficient Escherichia coli mutant. The protein was purified with its SAT activity, which was inhibited by cysteine, using the high affinity of the histidine tag in an Ni-NTA column. The Km values for acetyl-CoA and l-serine were 0.3 and 0.1 mM, respectively. Southern blotting indicated the existence of other SAT isoforms in C. merolae. A 2.4 kb transcript was always detected when growth was synchronized under a 12-h light/dark cycle. Under these conditions, a 31-kDa protein was always detected on immunoblots, indicating processing of the cmSAT protein and constitutive expression of cmSAT. A 45-kDa protein, thought to be the unprocessed cmSAT protein, was detected in the dark period, from M phase to early G1 phase. No significant change in the level of protein expression was detected under continuous darkness or in a sulfate-deficient medium. Using immunoelectron microscopy, the cmSAT protein was primarily detected in the stroma and a few were detected in the cytoplasm, which indicate that cmSAT protein is transported to and functions in a chloroplast.

Direct evidence that protein kinase C plays an essential role in the development of late preconditioning against myocardial stunning in conscious rabbits and that epsilon is the isoform involved

Brief ischemic episodes confer marked protection against myocardial stunning 1-3 d later (late preconditioning [PC] against stunning). The mechanism of this powerful protective effect is poorly understood. Although protein kinase C (PKC) has been implicated in PC against infarction, it is unknown whether it triggers late PC against stunning. In addition, the entire PKC hypothesis of ischemic PC remains controversial, possibly because the effects of PKC inhibitors on PC protection have not been correlated with their effects on PKC activity and/or translocation in vivo. Thus, conscious rabbits underwent a sequence of six 4-min coronary occlusion (O)/4-min reperfusion (R) cycles for three consecutive days (days 1, 2, and 3). In the control group (group I, n = 7), the recovery of systolic wall thickening after the six O/R cycles was markedly improved on days 2 and 3 compared with day 1, indicating the development of late PC against stunning. Administration of the PKC inhibitor chelerythrine at a dose of 5 mg/kg before the first O on day 1 (group II, n = 10) abrogated the late PC effect against stunning, whereas a 10-fold lower dose (0.5 mg/kg; group III, n = 7) did not. Administration of 5 mg/kg of chelerythrine 10 min after the sixth reperfusion on day 1 (group IV, n = 6) failed to block late PC against stunning. When rabbits were given 5 mg/kg of chelerythrine in the absence of O/R (group V, n = 5), the severity of myocardial stunning 24 h later was not modified. Pretreatment with phorbol 12-myristate 13-acetate (4 microg/kg) on day 1 without ischemia (group VI, n = 11) induced late PC against stunning on day 2 and the magnitude of this effect was equivalent to that observed after ischemic PC. In vehicle-treated rabbits (group VIII, n = 5), the six O/R cycles caused translocation of PKC isoforms epsilon and eta from the cytosolic to the particulate fraction without significant changes in total PKC activity, in the subcellular distribution of total PKC activity, or in the subcellular distribution of the alpha, beta1, beta2, gamma, delta, zeta, iota, lambda, and mu isoforms. The higher dose of chelerythrine (5 mg/kg; group X, n = 5) prevented the translocation of both PKC epsilon and eta induced by ischemic PC, whereas the lower dose (0.5 mg/kg; group XI, n = 5) prevented the translocation of PKC eta but not that of epsilon, indicating that the activation of epsilon is necessary for late PC to occur whereas that of eta is not. To our knowledge, this is the first demonstration that a PKC inhibitor actually prevents the translocation of PKC induced by ischemic PC in vivo, and that this inhibition of PKC translocation results in loss of PC protection. Taken together, the results demonstrate that the mechanism of late PC against myocardial stunning in conscious rabbits involves a PKC-mediated signaling pathway, and implicate epsilon as the specific PKC isoform responsible for the development of this cardioprotective phenomenon.

Diesel exhaust particles enhance airway responsiveness following allergen exposure in mice

We have previously reported that intratracheal instillation of diesel exhaust particles (DEP) enhances allergen-induced eosinophilic airway inflammation, local expression of interleukin-5 and granulocyte macrophage-colony stimulating factor, and allergen-specific production of IgE and IgG in mice. The present study was undertaken to elucidate the effects of DEP on airway hyperresponsiveness as another characteristic feature of allergic asthma. The animals were randomized into four experimental groups that received intratracheal instillation with vehicle, ovalbumin (OVA), DEP, or the combination of OVA and DEP on a weekly basis for 6 weeks. Respiratory resistance (Rrs) was measured 24 h after the last instillation. An increase in Rrs in animals that inhaled acetylcholine was significantly greater in the combined treatment with OVA and DEP than in the other treatments. The present study indicates that DEP can enhance airway responsiveness associated with allergen exposure, and provides experimental evidence that DEP may deteriorate the pathophysiology of allergen-related respiratory disease such as allergic asthma.

Advanced nasopharyngeal carcinoma treated with chemotherapy and radiotherapy: distant metastasis and local recurrence

One hundred and twenty-nine patients with NPC treated at the Department of Radiology, Chiba University Hospital and Keio University Hospital from 1980 through 1993 were selected for this study. Forty-four patients received cisplatin (CDDP)- or carboplatin-based chemotherapy, and 58 patients received adriamycin (ADM)- and/or 5-FU-based chemotherapy. The remaining 27 patients were treated with radiotherapy alone. The median radiation dose to the nasopharyngeal region was 64 Gy, and to the initially involved cervical node, 60 Gy. The 5 year survival rates for the CDDP, the ADM/5-FU and the radiation alone groups were 61%, 47% and 42%, respectively. The cumulative incidences of local control in the CDDP, the ADM/5-FU and the radiation alone groups were 77%, 49% and 53% respectively. The CDDP group achieved the significantly better local control (CDDP vs ADM: p=0.001). The overall incidence of distant metastases was 54% in the CDDP group. On the other hand, it was 24% in the ADM/5-FU group and 22% in the radiation alone group (CDDP vs ADM: p=0.048). While the locoregional control rate was significantly better in the CDDP given group, more distant metastases were seen in this group.

Development of design methods of a centrifugal blood pump with in vitro tests, flow visualization, and computational fluid dynamics: results in hemolysis tests

There are few established engineering guidelines aimed at reducing hemolysis for the design of centrifugal blood pumps. In this study, a fluid dynamic approach was applied to investigate hemolysis in centrifugal pumps. Three different strategies were integrated to examine the relationship between hemolysis and flow patterns. Hemolytic performances were evaluated in in vitro tests and compared with the flow patterns analyzed by flow visualization and computational fluid dynamic (CFD). Then our group tried to establish engineering guidelines to reduce hemolysis in the development of centrifugal blood pumps. The commercially available Nikkiso centrifugal blood pump (HPM-15) was used as a standard, and the dimensions of 2 types of gaps between the impeller and the casing, the axial and the radial gap, were varied. Four impellers with different vane outlet angles were also prepared and tested. Representative results of the hemolysis tests were as follows: The axial gaps of 0.5, 1.0, and 1.5 mm resulted in normalized index of hemolysis (NIH) values of 0.0028, 0.0013 and 0.0008 g/100 L, respectively. The radial gaps of 0.5 and 1.5 mm resulted in NIH values of 0.0012 and 0.0008 g/100 L, respectively. The backward type vane and the standard one resulted in NIH values of 0.0013 and 0.0002 g/100 L, respectively. These results revealed that small gaps led to more hemolysis and that the backward type vane caused more hemolysis. Therefore, the design parameters of centrifugal blood pumps could affect their hemolytic performances. In flow visualization tests, vortices around the impeller outer tip and tongue region were observed, and their patterns varied with the dimensions of the gaps. CFD analysis also predicted high shear stress consistent with the results of the hemolysis tests. Further investigation of the regional flow patterns is needed to discuss the cause of the hemolysis in centrifugal blood pumps.

Characterization of rbcL group IA introns from two colonial volvocalean species (Chlorophyceae)

Group I introns were reported for the first time in the large subunit of Rubisco (rbcL) genes, using two colonial green algae, Pleodorina californica and Gonium multicoccum (Volvocales). The rbcL gene of P. californica contained an intron (PIC intron) of 1320 bp harboring an open reading frame (ORF). The G. multicoccum rbcL gene had two ORF-lacking introns of 549 (GM1 intron) and 295 (GM2 intron) base pairs. Based on the conserved nucleotide sequences of the secondary structure, the PIC and GM1 introns were assigned to group IA2 whereas the GM2 intron belonged to group IA1. Southern hybridization analyses of nuclear and chloroplast DNAs indicated that such intron-containing rbcL genes are located in the chloroplast genome. Sequencing RNAs from the two algae revealed that these introns are spliced out during mRNA maturation. In addition, the PIC and GM1 introns were inserted in the same position of the rbcL exons, and phylogenetic analysis of group IA introns indicated a close phylogenetic relationship between the PIC and GM1 introns within the lineage of bacteriophage group IA2 introns. However, P. californica and G. multicoccum occupy distinct clades in the phylogenetic trees of the colonial Volvocales, and the majority of other colonial volvocalean species do not have such introns in the rbcL genes. Therefore, these introns might have been recently inserted in the rbcL genes independently by horizontal transmission by viruses or bacteriophage.

Prolonged nonpulsatile left heart bypass with reduced systemic pulse pressure causes morphological changes in the aortic wall

We investigated the morphological changes in the aorta due to reduced systemic pulse pressure in prolonged nonpulsatile left heart bypass (LHB). Nineteen adult goats were divided into 3 groups, the nonpulsatile group in which nonpulsatile LHB was conducted, the pulsatile group in which pulsatile LHB was conducted, and the control group used as the normal control. The average aortic pulse pressures were 12, 47, and 37 mm Hg, respectively. The descending aorta was subjected to morphological examination. In the nonpulsatile group, the wall was significantly thinner, and the volume ratio of smooth muscle cells (SMCs) was much lower. In terms of the SMC type classification, the proportion of SMCs with low activity and low contractility was higher, and the cell density of the SMCs was increased compared to those in the other groups. These results indicate that prolonged nonpulsatile LHB causes morphological atrophic changes in the aorta.

Homolog of a-factor receptor gene in Saccharomyces exiguus

Homologs of Saccharomyces cerevisiae STE3, a-factor receptor gene were detected from S. exiguus NFRI 3539 by low stringency Southern hybridization. This strain might have at least two types of homolog. One of these homologs, designated as e-STE3 was cloned. Its nucleotide sequence revealed 60% identity to STE3. The putative protein coding region consisted of 453 amino acid residues. The amino acid sequence identity between STE3 and e-STE3 was 62% and that of the N-terminal 303 amino acid residues considered to be the pheromone binding domain was 79%.

Separation of killing and tumorigenic effects of an alkylating agent in mice defective in two of the DNA repair genes

Alkylation of DNA at the O6-position of guanine is one of the most critical events leading to mutation, cancer, and cell death. The enzyme O6-methylguanine-DNA methyltransferase repairs O6-methylguanine as well as a minor methylated base, O4-methylthymine, in DNA. Mouse lines deficient in the methyltransferase (MGMT) gene are hypersensitive to both the killing and to the tumorigenic effects of alkylating agents. We now show that these dual effects of an alkylating agent can be dissociated by introduction of an additional defect in mismatch repair. Mice with mutations in both alleles of the MGMT gene and one of the mismatch repair genes, MLH1, are as resistant to methylnitrosourea (MNU) as are wild-type mice, in terms of survival, but do have numerous tumors after receiving MNU. In contrast to MGMT-/- MLH1(+/+) mice with decrease in size of the thymus and hypocellular bone marrow after MNU administration, no conspicuous change was found in MGMT-/- MLH1(-/-) mice treated in the same manner. Thus, killing and tumorigenic effects of an alkylating agent can be dissociated by preventing mismatch repair pathways.

The role of an inverted CCAAT element in transcriptional activation of the human DNA topoisomerase IIalpha gene by heat shock

Expression of the DNA topoisomerase IIalpha (topoIIalpha) gene is highly sensitive to various environmental stimuli including heat shock. The amount of topoIIalpha mRNA was increased 1.5-3-fold 6-24 h after exposure of T24 human urinary bladder cancer cells to heat shock stress at 43 degreesC for 1 h. The effect of heat shock on the transcriptional activity of the human topoIIalpha gene promoter was investigated by transient transfection of T24 cells with luciferase reporter plasmids containing various lengths of the promoter sequence. The transcriptional activity of the full-length promoter (nucleotides (nt) -295 to +85) and of three deletion constructs (nt -197 to +85, -154 to +85, and -74 to +85) was increased approximately 3-fold 24 h after heat shock stress. In contrast, the transcriptional activity of the minimal promoter (nt -20 to +85), which lacks the first inverted CCAAT element (ICE1), the GC box, and the heat shock element located between nt -74 and -21, was not increased by heat shock. Furthermore, the transcriptional activity of promoter constructs containing mutations in the GC box or heat shock element, but not that of a construct containing mutations in ICE1, was significantly increased by heat shock. Electrophoretic mobility shift assays revealed reduced binding of a nuclear factor to an oligonucleotide containing ICE1 when nuclear extracts were derived from cells cultured for 3-24 h after heat shock. No such change in factor binding was apparent with an oligonucleotide containing the heat shock element of the topoIIalpha gene promoter. Finally, in vivo footprint analysis of the topoIIalpha gene promoter revealed that two G residues of ICE1 that were protected in control cells became sensitive to dimethyl sulfate modification after heat shock. These results suggest that transcriptional activation of the topoIIalpha gene by heat shock requires the release of a negative regulatory factor from ICE1.

Occludin-deficient embryonic stem cells can differentiate into polarized epithelial cells bearing tight junctions

Occludin is the only known integral membrane protein of tight junctions (TJs), and is now believed to be directly involved in the barrier and fence functions of TJs. Occludin-deficient embryonic stem (ES) cells were generated by targeted disruption of both alleles of the occludin gene. When these cells were subjected to suspension culture, they aggregated to form simple, and then cystic embryoid bodies (EBs) with the same time course as EB formation from wild-type ES cells. Immunofluorescence microscopy and ultrathin section electron microscopy revealed that polarized epithelial (visceral endoderm-like) cells were differentiated to delineate EBs not only from wild-type but also from occludin-deficient ES cells. Freeze fracture analyses indicated no significant differences in number or morphology of TJ strands between wild-type and occludin-deficient epithelial cells. Furthermore, zonula occludens (ZO)-1, a TJ-associated peripheral membrane protein, was still exclusively concentrated at TJ in occludin-deficient epithelial cells. In good agreement with these morphological observations, TJ in occludin-deficient epithelial cells functioned as a primary barrier to the diffusion of a low molecular mass tracer through the paracellular pathway. These findings indicate that there are as yet unidentified TJ integral membrane protein(s) which can form strand structures, recruit ZO-1, and function as a barrier without occludin.