Study on the reaction mechanism of C-6 lithiation of pyrimidine nucleosides by using lithium hexamethyldisilazide as a base

The reaction mechanism of C-6 lithiation of uridine mediated by lithium hexamethyldisilazide (LiHMDS) has been investigated. LiHMDS alone dose not lithiate at C-6 of uridine. However, in the presence of an appropriate silylating agent, e.g. trimethylsilyl chloride, the reaction of 1 with LiHMDS allowed to lithiate at C-6 and gave the corresponding C-6 silylated product 2. The experimental results shown below revealed that O-4 (N-3) of uracil moiety may be temporarily masked by silylation, which triggers the C-6 lithiation by lowering the pKa of H-6. The reaction could efficiently be applied to the synthesis of 6,5'-C-cyclouridine, a nucleoside analogue fixed in a specific glycosyl torsion angle by a carbon-carbon bridge.

Embryonic stem cells injected into the mouse knee joint form teratomas and subsequently destroy the joint

OBJECTIVE

To determine whether the joint space is a suitable environment for embryonic stem (ES) cells to grow and form cartilage.

METHOD

We transplanted ES cells into the knee joint and a subcutaneous space of mice with severe combined immunodeficiency.

RESULTS

Teratomas formed in both areas. Those in the joints grew and destroyed the joints. The incidence of cartilage formation was the same in the knee joint and subcutaneous space, but the ratio of cartilage to teratoma was higher in the knee joint than in the subcutaneous space. The teratomas were proved to have been derived from the transplanted ES cells by detection of the neomycin-resistance gene that had been transfected into the ES cells.

CONCLUSIONS

It is currently not possible to use ES cells to repair joint tissues. Further optimization of donor ES cells to differentiate as well as inhibit tumour growth may help to meet these challenges.

Adeno-associated virus vector-mediated gene transfer into dystrophin-deficient skeletal muscles evokes enhanced immune response against the transgene product

Duchenne muscular dystrophy (DMD) is an X-linked, lethal muscular disorder caused by a defect in the DMD gene. AAV vector-mediated micro-dystrophin cDNA transfer is an attractive approach to treatment of DMD. To establish effective gene transfer into skeletal muscle, we examined the transduction efficiency of an AAV vector in skeletal muscles of dystrophin-deficient mdx mice. When an AAV vector encoding the LacZ gene driven by a CMV promoter (AAV-CMVLacZ) was introduced, beta-galactosidase expression markedly decreased in mdx muscle 4 weeks after injection due to immune responses against the transgene product. We also injected AAV-CMVLacZ into skeletal muscles of mini-dystrophin-transgenic mdx mice (CVBA3'), which show ameliorated phenotypes without overt signs of muscle degeneration. AAV vector administration, however, evoked substantial immune responses in CVBA3' muscle. Importantly, AAV vector using muscle-specific MCK promoter also elicited responses in mdx muscle, but at a considerably later period. These results suggested that neo-antigens introduced by AAV vectors could evoke immune reactions in mdx muscle, since increased permeability allowed a leakage of neo-antigens from the dystrophin-deficient sarcolemma of muscle fibers. However, resident antigen-presenting cells, such as myoblasts, myotubes and regenerating immature myofibers, might also play a role in the immune response.

The effect of head posture on the pharyngeal airway space (PAS)

The purpose of this study was to investigate the relationship between cranio-cervical inclination and pharyngeal airway space (PAS) by measuring these parameters at different head postures in the same subjects and to obtain a regression equation to correct the values measured. Fifty lateral cephalometric radiographs taken at five different head postures per individual were obtained from ten adults (seven males and three females) aged from 25 to 30 years with nose breathers and Class I occlusion. The changes in cranio-cervical inclination produced by head extension were correlated with changes in the variables describing the PAS. The OPT/NSL (cranio-cervical inclination in the second vertebrae) and C3-Me (distance between the third vertebrae and the Menton) correlated strongly with PAS-TP (the most proximal distance measured between the posterior pharyngeal wall and the tongue base) in the pharyngeal airway space (r = 0.807 and 0.854 respectively). The regression equations were Y = - 27.177+0.39X (Y = PAS-TP, X = OPT/NSL), and Y = -21.105+0.402X (Y = PAS-TP, X = C3-Me), respectively. From these equations we could conclude that an increase of 10 degrees in OPT/NSL or 10 mm in C3-Me increased the pharyngeal airway space (PAS-TP) by about 4 mm.

Haemodynamic and splanchnic organ blood-flow responses to hypotension induced by the calcitonin gene-related peptide and sodium nitroprusside in dogs

BACKGROUND AND OBJECTIVE

To elucidate the effects of various degrees of hypotension induced by the calcitonin gene-related peptide (CGRP) on the splanchnic circulation, we investigated the renal and hepatic blood flow during hypotension induced by either the calcitonin gene-related peptide or sodium nitroprusside in the isoflurane-anaesthetized dog.

METHODS

Anaesthesia was maintained with 1.3% isoflurane in oxygen. After the baseline period, mean arterial pressure was reduced to 60 mmHg in the CGRP60 and nitroprusside groups, and to 50 mmHg in the CGRP50 group. The splanchnic organ blood flow was measured by hydrogen clearance.

RESULTS

The cardiac index in the CGRP60 group increased (P < 0.01), but in the CGRP50 group it decreased (P < 0.01), and in the nitroprusside group it remained unchanged during hypotension. Mean pulmonary artery and pulmonary capillary wedge pressures in the CGRP60 group remained unchanged, but in the CGRP50 and nitroprusside groups they decreased (P < 0.01) during hypotension. Cardiac contractility in the CGRP60 group remained unchanged, whereas in the CGRP50 and nitroprusside groups it was reduced (P < 0.01) during hypotension. Renal blood flow in the CGRP60 group was relatively well maintained but in the CGRP50 and nitroprusside groups it was reduced (P < 0.01) throughout the observation. Hepatic blood flow in all three groups was reduced (P < 0.01) during hypotension. The reductions in hepatic blood flow between the Calcitonin gene-related peptide groups were associated with a dose-dependent decrease in mean arterial pressure.

CONCLUSIONS

The results suggest that calcitonin gene-related peptide acts as an arteriolar vasodilator at low doses but as a vasodilator of the arteriolar and venous systems at higher doses, and that profound hypotension induced by the calcitonin gene-related peptide may impair splanchnic circulation.

Haemodynamic and splanchnic organ blood flow responses during sevoflurane-induced hypotension in dogs

BACKGROUND AND OBJECTIVE

The safety of hypotension induced by sevoflurane and splanchnic organ blood flow remains to be clarified. The aim was to investigate the effects of sevoflurane-induced hypotension on systemic haemodynamics and splanchnic organ blood flows in dogs.

METHODS

Mean arterial pressure was maintained at 60 mmHg by increasing sevoflurane concentrations. The renal, hepatic and pancreatic blood flows were measured by using the hydrogen clearance method.

RESULTS

Hypotension induced by sevoflurane resulted in a 50% decrease of mean arterial pressure due to a 30% reduction in systemic vascular resistance associated with a 30% decrease in cardiac index. The mechanisms causing the lower cardiac index were produced by the decreases in heart rate and left ventricular dP/dt(max). Renal, hepatic and pancreatic blood flow were reduced, but the whole-body oxygen consumption did not change during the hypotensive period.

CONCLUSIONS

The haemodynamic changes induced by sevoflurane were caused by the suppression of arterial baroreflexes and myocardial depression, but splanchnic organ blood flows, though reduced, could provide adequate peripheral perfusion to meet the decrease in oxygen supply.

Changes in osteoprotegerin and markers of bone metabolism during glucocorticoid treatment in patients with chronic glomerulonephritis

It is well known that long-term glucocorticoid treatment causes osteoporosis, but the precise mechanism remains unclear. Recently, osteoprotegerin (OPG) has been identified as a cytokine that inhibits osteoclast differentiation. We have previously demonstrated that serum OPG is suppressed by glucocorticoids. Therefore, the present study was carried out to clarify the interrelationships between OPG and other markers of bone metabolism during glucocorticoid treatment. Thirteen patients (7 men, 6 women; 44.1 +/- 5.9 years old) with chronic glomerulonephritis who were to be treated with glucocorticoids for the first time were chosen for this study. Markers of bone metabolism, including serum OPG, osteocalcin (OC), bone-specific alkaline phosphatase activity (bAP), parathyroid hormone (PTH), tartrate-resistant acid phosphatase (TRAP), and bone mineral density (BMD), were measured before and during the treatment period. Glucocorticoids significantly reduced BMD of the lumbar spine in the 6 month treatment period (p < 0.01). Serum OPG was decreased significantly by glucocorticoids within 2 weeks (p < 0.001), and serum TRAP, a marker of bone resorption, was markedly increased (p < 0.001). On the other hand, there were no remarkable changes in serum PTH. Serum OC and bAP, markers of bone formation, were transiently reduced during the treatment period (p < 0.01). Furthermore, only serum OPG was positively and independently correlated with percentage BMD of age-matched reference (%AMR). These findings imply that glucocorticoid-induced bone loss develops rapidly via enhanced bone resorption and suppressed bone formation. Moreover, the increased bone resorption caused by glucocorticoids may be, at least in part, mediated by inhibition of OPG, not increment of PTH.

ED-71, a vitamin D analog, is a more potent inhibitor of bone resorption than alfacalcidol in an estrogen-deficient rat model of osteoporosis

Although active vitamin D is used in certain countries for the treatment of osteoporosis, the risk of causing hypercalcemia/hypercalciuria means that there is only a narrow therapeutic window, and this has precluded worldwide approval. The results of our previous animal studies have suggested that the therapeutic effect of active vitamin D on bone loss after estrogen deficiency can be dissociated at least partly from its effect of enhancing intestinal calcium absorption and suppressing parathyroid hormone (PTH) secretion. To test this, we compared the effects of ED-71, a hydroxypropoxy derivative of 1alpha,25-dihydroxyvitamin D3, with orally administered alfacalcidol, on bone mineral density (BMD) and the bone remodeling process as a function of their effects on calcium metabolism and PTH, in a rat ovariectomy (ovx) model of osteoporosis. ED-71 increased bone mass at the lumbar vertebra to a greater extent than alfacalcidol, while enhancing calcium absorption (indicated by urinary calcium excretion) and decreasing serum PTH levels to the same degree as alfacalcidol. ED-71 lowered the biochemical and histological parameters of bone resorption more potently than alfacalcidol, while maintaining bone formation markers. These results suggest that active vitamin D exerts an antiosteoporotic effect by inhibiting osteoclastic bone resorption while maintaining osteoblastic function, and that these anticatabolic/anabolic effects of active vitamin D take place independently of its effects on calcium absorption and PTH. The demonstration that ED-71 is more potent in these properties than alfacalcidol makes it an attractive candidate as an antiosteoporotic drug.

Delayed rupture of a pseudoaneurysm following pancreatoduodenectomy: report of a case

We report herein the case of a 63-year-old man in whom delayed rupture of a pseudoaneurysm occurred 120 days following pancreatoduodenectomy. Color Doppler examination indicated a pseudoaneurysm originating from the ligated gastroduodenal artery. Transcatheter arterial embolization was done at the common hepatic artery, proximal and distal to the pseudoaneurysm, with microcoils. The patient had a minor elevation of liver enzymes, which subsequently returned to normal. Due to the absence of any postoperative complications such as pancreatic anastomotic leakage, we assumed that the pseudoaneurysm formation had been caused by a weakness in the arterial wall according to skeletonization resulting from lymphadenectomy and intraoperative radiation therapy. To our knowledge, this case represents the longest interval between pancreatoduodenectomy and rupture of a pseudoaneurysm ever to be reported in the literature.

Long-term treatment with nicardipine for severe pre-eclampsia

OBJECTIVE

To evaluate the safety of long-term nicardipine treatment in severely pre-eclamptic women and their fetuses/newborns.

METHODS

We divided 50 pregnant women into three groups according to the length of their treatment: short-term treatment of severely pre-eclamptic women (7 days or less, n=20); medium-term treatment also of severely pre-eclamptic women (8-28 days, n=20); and long-term treatment of women with severe superimposed pre-eclampsia (29 days or more, n=10).

RESULTS

Nicardipine significantly lowered both systolic (P<0.01) and diastolic blood pressures (P<0.025) in all three groups. The incidence of delivery before 28 weeks of gestation was very low in all three groups. There were no maternal or fetal/neonatal adverse effects.

CONCLUSION

Our results suggest that long-term treatment with nicardipine for severe pre-eclampsia is as effective and safe as a short- and medium-term treatment.

DNA repair studies: experimental evidence in support of chicken DT40 cell line as a unique model

DT40 is a chicken B lymphocyte cell line that exhibits a high ratio of targeted and random integration of transfected DNA constructs. Using the DT40 cell line makes it comparatively easy to disrupt multiple genes in a single cell and to generate conditional targeted mutants including tet-controlled cre-lox-mediated and temperature-sensitive mutants. The DT40 mutants show a strong phenotypic resemblance to murine mutants with respect to genes involved in DNA recombination and repair. Because of these characteristics, DT40 is an attractive model for the analysis of DNA recombination and repair studies in vertebrates despite obvious concerns associated with the use of a transformed cell line that may have certain cell-line-specific characteristics. We present experimental evidence to demonstrate the usefulness of the DT40 cell line as a unique model to study DNA damaging events and their associated repair pathways.

The expression of dystrophin and alpha1-syntrophin during skeletal muscle regeneration

The expression of dystrophin and alpha1-syntrophin in rat tibialis anterior muscles were evaluated during a cycle of regeneration after myonecrosis induced by the injection of cardiotoxin. Immunohistochemical studies were performed in cryosections of muscles on days 1, 3, 5, 7, 10, 14, 21 and 28 after injection of cardiotoxin. Western blot analysis was also examined in muscle on days 1, 3, 5, 7, 10, 14, 21 and 28. In immunohistochemical studies, dystrophin was stained weakly at the sarcolemma of some regenerating muscle fibers on day 3, and by day 10 it was stained strongly on almost all regenerating muscle fibers. Alpha1-syntrophin was stained weakly at the sarcolemma of some regenerating fibers on day 5, and by day 14 it was detected on all regenerating muscle fibers. In Western blot analysis, dystrophin (DYS1) and alpha1-syntrophin (alpha1S) were completely absent on day 1. Re-expression of DYS1 and alpha1S was visible by day 5 and accelerated thereafter. The Western blots of DYS1 and alpha1S were densitometrically analyzed on each day. The protein levels on each day were converted to the percentage of the protein level on day 28, which was taken as 100%. From the sequential line based on these data, the following results were obtained on the chronological course of DYS1 and alpha1S. DYS1: 25% of the protein level on day 28 was reached by 3.5 days, 50% was reached by 5.3 days, and 90% was reached by 6.9 days. Alpha1S: 25% of the protein level on day 28 was reached by 4.6 days, 50% was reached by 6.0 days, and 90% was reached by 12.5 days. In this study, DYS1 regenerated earlier than alpha1S at the sarcolemma of regenerating muscle fibers.

Gene therapy for muscular dystrophies: current status and future prospects

Since the identification in 1987 of the gene for Duchenne muscular dystrophy (DMD), research on the molecular pathogenesis of muscular dystrophy has progressed extensively. In particular, discovery of the DMD gene product, dystrophin, led to the identification of dystrophin-associated proteins and, subsequently, the recognition of other types of muscular dystrophy caused by the defects in each of the sarcoglycan genes. On the other hand, effective therapy for DMD has not yet been established. Some of the viral vectors, such as adeno-associated virus vectors or lentiviral vector, have been proven to enable the long-term expression of the exogenous gene without overt host immune reactions. However, dystrophin cDNAs are too large (14kb) to be accommodated in these viral vectors. To solve this problem, we and other research groups succeeded in truncating full-length dystrophin cDNA to small dystrophin cDNA (4 to 5kb), the products of which protect dystrophin-deficient mdx muscle from contraction-induced membrane damage when introduced by viral vectors or as a transgene into mdx mice. The usefulness of these truncated dystrophin cDNAs should be confirmed using other animal models such as dystrophic dogs. To develop successful treatment of DMD, the authors believe that several different approaches should be used, such as cell transfer therapy, drug design to up-regulate utrophin, or a strategy to repair the mutation in vivo.

[Development of new therapy on muscular dystrophy]

Duchenne muscular dystrophy (DMD) is an X-linked, lethal disorder caused by a defect in the DMD gene. We have previously reported that micro-dystrophins, which have large deletions in rod repeat domain, successfully localize at the sarcolemma and stabilize dystroglycan-sarcoglycan complex in dystrophin-deficient mdx muscle. However, expression of a 3.7-kb micro-dystrophin cDNA, having only one rod repeat showed no effect on dystrophic phenotype. Further transgenic experiments are carrying to seek a functional but small-sized micro-dystrophin cDNA, which can be accommodated into Adeno-associated virus (AAV) vector. In normal muscle, AAV-LacZ vector expresses stably beta-gal for a long period, however, we noticed that immune response is evoked by AAV-LacZ vector in mdx muscle. Therefore, for successful gene therapy, it is required to reduce immune response against AAV-dystrophin vector and therapeutic proteins in mdx mice. We have already reported that utrophin was up-regulated at the sarcolemma of mdx mice, when a beta-galactosidase-expressing adenovirus vector, AxCALacZ was injected into the skeletal muscle. Moreover, up-regulated utrophin mitigated dystrophic phenotypes. Up-regulation of utrophin was induced by inflammatory response against adenovirus vector-mediated gene transfer and this up-regulation is one of promising tools for treatment of DMD.

Prediction of symptom-onset in aortic stenosis: a comparison of pressure drop/flow slope and haemodynamic measures at rest

To compare the pressure drop/flow slope with peak and mean pressure drop, effective orifice area and aortic valve resistance for the prediction of symptom-onset we performed resting and dobutamine stress echocardiography in 49 asymptomatic patients with aortic stenosis (peak aortic velocity>2.5 m/s). The end-point was progression to symptoms requiring surgery and patients were followed for a mean 21.2 (5.2) months. A total of 23 (47%) patients progressed to symptoms requiring aortic valve replacement and 26 remained asymptomatic. There was no significant difference in age, gender, fractional shortening or the presence or absence of coronary artery disease between these groups. There were differences in peak aortic velocity (P<0.0001), peak and mean pressure drop (P<0.0001), effective orifice area (P=0.03), aortic valve resistance (P=0.001) and pressure drop/flow slope (P<0.0001). On Cox regression analysis, the pressure drop/flow slope (P<0.0001), peak aortic velocity (P=0.005) and peak pressure gradient (P=0.02) were independent predictors. Mean event-free survival at 2 years for peak velocity >4.0 m/s was 17% and for pressure drop/flow slope >0.10 mmHg/ms(-1) was 20%. Of 13 patients reporting symptoms during dobutamine stress, 10 (77%) developed spontaneous symptoms during follow-up compared with 13 of 36 (36%) with no symptoms (P=0.11). The pressure drop/flow slope is a better independent predictor of symptom onset than resistance, mean pressure difference and effective orifice area, but is similar to peak velocity.

Scc1/Rad21/Mcd1 is required for sister chromatid cohesion and kinetochore function in vertebrate cells

Proteolytic cleavage of the cohesin subunit Scc1 is a consistent feature of anaphase onset, although temporal differences exist between eukaryotes in cohesin loss from chromosome arms, as distinct from centromeres. We describe the effects of genetic deletion of Scc1 in chicken DT40 cells. Scc1 loss caused premature sister chromatid separation but did not disrupt chromosome condensation. Scc1 mutants showed defective repair of spontaneous and induced DNA damage. Scc1-deficient cells frequently failed to complete metaphase chromosome alignment and showed chromosome segregation defects, suggesting aberrant kinetochore function. Notably, the chromosome passenger INCENP did not localize normally to centromeres, while the constitutive kinetochore proteins CENP-C and CENP-H behaved normally. These results suggest a role for Scc1 in mitotic regulation, along with cohesion.

Measurement of the length of the a helical section of a peptide directly using atomic force microscopy

Using atomic force microscopy (AFM), the length of the alpha-helix structure of poly-L-lysine was investigated by stretching the peptide directly, one molecule at a time. In the absence of urea, many rupturing points that seemed to be due to the breaking of some hydrogen bonds were observed in force-extension curves, while these points were never observed in the presence of 8 M urea. In the presence of 0.4 or 1.6 M urea, both force-extension curve types were observed. Total peptide elongation for each condition was calculated from force-extension curves reflecting the alpha-helix rupturing process. The experimental value of total elongation divided by the theoretical value of total alpha-helix elongation yields the alpha-helix content. This value was compatible with circular dichroism (CD) measurement results. This suggests that peptide conformation and content of the alpha-helix on a single molecule scale can be investigated by direct mechanical measurement using atomic force microscopy.

Noninvasive assessment of arterial distensibility in adolescents using the second derivative of photoplethysmogram waveform

To clarify the clinical usefulness of the second derivative of the waveform of the fingertip photoplethysmogram (SDPTG), we examined the relationship between the pattern of the SDPTG waveform and risk factors related to atherosclerosis in 1,495 boys and girls aged 9-17 years. The fingertip photoplethysmogram and its second derivative wave were automatically recorded from the second digit of the right hand with the subjects lying in a supine position. The SDPTG waveform consisted of a, b, c and d waves in systole and an e wave in diastole. The heights of the a and d waves were measured from the baseline, and the ratio of the height of the d wave to that of the a wave (d/a ratio) was calculated. The d/a ratio had a negative correlation with the systolic (SBP) and diastolic blood pressures (DBP), atherogenic index (AI) and immunoreactive insulin concentrations (IRI) after adjustment for age. Multiple linear regression analysis revealed that the d/a ratio was associated more with body height than the risk factors for atherosclerosis in boys and girls at the growth period. The effect of sex- and height-specific cutoff values of the 10th percentile for the d/a ratio was therefore tested. The results showed that subjects with d/a ratios lower than the 10th percentile had significantly higher SBP, DBP, AI and IRI values compared to those with higher d/a ratios. These findings suggest that differences in the length of the vascular system, which are related to increases in body height, may modify the SDPTG waveform pattern during adolescence. When the body height as well as age and sex is adequately allowed for, the d/a ratio may be useful for the evaluation of arterial distensibility and for identification of individuals at an increased risk of developing atherosclerosis.

Pro-apoptotic effect of presenilin 2 (PS2) overexpression is associated with down-regulation of Bcl-2 in cultured neurons

Presenilin 2 (PS2) is a polytopic membrane protein that is mutated in some cases of familial Alzheimer's disease (AD). The normal functions of PS2 and its pathogenic role in AD remain unclear. We investigated the biological role of this protein in neurons, using adenovirus-mediated transduction of the PS2 gene into rat primary cortical neurons. Immunocytochemical analyses demonstrated increased PS2 immunoreactivity in most neurons infected with recombinant adenoviruses expressing PS2. Neurons infected with wild-type or mutant (N141I) PS2-expressing adenoviruses showed a significant increase in basal cell death, compared with those infected with control beta-galactosidase-expressing adenovirus. Moreover, PS2 overexpression markedly increased neuronal susceptibility to staurosporine-induced apoptosis. Mutant PS2 was more effective in enhancing apoptosis than its wild-type counterpart. Staurosporine-induced death was significantly inhibited by a specific caspase 3 inhibitor. Western analyses revealed that Bcl-2 protein expression was specifically down-regulated in neurons overexpressing PS2, which temporally corresponded to the accumulation of C- and N-terminal fragments of PS2. Additionally, expression of mutant, but not wild-type PS2, increased the production of beta-amyloid protein (Abeta) 42. These data collectively suggest that the pro-apoptotic effect of PS2 is mediated by down-regulation of Bcl-2. PS2 mutations may increase the susceptibility of neurons to apoptotic stimuli by perturbing the regulation of cell death.

Genetic analysis of the DNA-dependent protein kinase reveals an inhibitory role of Ku in late S-G2 phase DNA double-strand break repair

Two major complementary double-strand break (DSB) repair pathways exist in vertebrates, homologous recombination (HR), which involves Rad54, and non-homologous end-joining, which requires the DNA-dependent protein kinase (DNA-PK). DNA-PK comprises a catalytic subunit (DNA-PKcs) and a DNA-binding Ku70 and Ku80 heterodimer. To define the activities of individual DNA-PK components in DSB repair, we targeted the DNA-PKcs gene in chicken DT40 cells. DNA-PKcs deficiency caused a DSB repair defect that was, unexpectedly, suppressed by KU70 disruption. We have shown previously that genetic ablation of Ku70 confers RAD54-dependent radioresistance on S-G(2) phase cells, when sister chromatids are available for HR repair. To test whether direct interference by Ku70 with HR might explain the Ku70(-/-)/DNA-PKcs(-/-/-) radioresistance, we monitored HR activities directly in Ku- and DNA-PKcs-deficient cells. The frequency of intrachromosomal HR induced by the I-SceI restriction enzyme was increased in the absence of Ku but not of DNA-PKcs. Significantly, abrogation of HR activity by targeting RAD54 in Ku70(-/-) or DNA-PKcs(-/-/-) cells caused extreme radiosensitivity, suggesting that the relative radioresistance seen with loss of Ku70 was because of HR-dependent repair pathways. Our findings suggest that Ku can interfere with HR-mediated DSB repair, perhaps competing with HR for DSB recognition.

Design of an artificial light-harvesting unit by protein engineering: cytochrome b(562)-green fluorescent Protein chimera

We have generated a novel model protein for an artificial light-harvesting complex composed of two proteins, cytochrome b(562) (cytb(562)) and enhanced green fluorescent protein (EGFP), in which two chromophores are fixed in each protein matrix. Cytb(562) was appended to the N-terminus of EGFP via a Gly-Ser linker and the resultant fusion protein was successfully expressed in Escherichia coli as a mixture of the apo- and the holo-forms as to the cytb(562) moiety. The fluorescence of EGFP was substantially quenched when the apo-form was reconstituted with hemin. Based on the fluorescence lifetime measurements, it appeared that light energy entrapped by EGFP is transferred to the heme of cytb(562) by resonance energy transfer (energy transfer yield: 65%). Spatial organization of two chromophores using small and stable protein matrices will be promising toward the construction of an artificial light-harvesting complex by protein engineering.

Ionic channel structures in [(M+)x([18]crown-6)][Ni(dmit)2]2 molecular conductors

The [(M+)x[18]crown-6)] supramolecular cations (SC+), in which M+ and [18]crown-6 are alkali metal ions (M+ = Li+, Na+, and Cs+) and 1,4,7,10,13,16-hexaoxacyclooctadecane, respectively, form ionic channel structures through the regular stacks of [18]crown-6 in [Ni(dmit)2]-based molecular conductors (dmit2+ = 2-thioxo-1,3-dithiole-4,5-dithiolate). In addition to the [Ni(dmit)2] salts that have the ionic channel structures (these salts are abbreviated as type I salts), Li+ and Na+ form dimerized [(M+)2([18]crown-6)2] units in the crystals (type II salts). The K+ and Rb+ are coordinated tightly into the [18]crown-6 cavity to form typical disk-shape SC+ units in the corresponding [Ni(dmit)2] salts (type III salts). The type I, II, and III salts have typical stoichiometries of [(M+)x([18]crown-6)][Ni(dmit)2]2, [(M+)([18]crown-6)(H2O)x(CH3CN)(1.5 - x)][Ni(dmit)2]3 (x = 1 for Li+ or 0.5 for Na+), and [M+([18]crown-6)][Ni(dmit)2]3, respectively: the salts of the same type are isostructural. In agreement with the trimer structures of [Ni(dmit)2] in the type II and III salts, they exhibit semiconducting behavior with electrical conductivities at 300 K (sigma(300 K)) of 0.01-0.1 S cm(-1). Type I salts contain a regular stack of partially oxidized [Ni(dmit)2] units, which form a quasi one-dimensional metallic band within the tight-binding approximation regime. The electrical conductivities at 300 K are 10-30 S cm(-1), and an almost temperature-independent conductivity was observed at higher temperatures. However, the one-dimensional electronic structures in these salts are strongly influenced by the static and dynamic structures of the coexisting ionic channel. The Na+ salt is a semiconductor, whose magnetic behavior is described by the disordered one-dimensional antiferromagnetic chain. On the other hand, the Cs+ salt is a exhibits metallic properties with 2 kF instability at room temperature. The Li+ salt shows a gradual transition from the high-temperature metallic phase to the low-temperature one-dimensional antiferromagnetic semiconductor phase, which was associated with the freezing of Li+ motion at lower temperatures. The preferential crystallization of type I salts was possible by controlling the equilibrium constant (Kc) of the complex formation between M+ ions and the [18]crown-6 molecule. The ionic channel structures were obtained when the KC was low in the electrocrystallization solution, while type II or III salts were formed in the high Kc region.

[Role of new devices for angioplasty in the unprotected left main coronary artery]

OBJECTIVES

Angioplasty for the unprotected left main trunk remains controversial, but new procedures and devices such as directional coronary atherectomy and stenting have improved the results. We compared the results of angioplasty with the inflexible balloon and new devices.

METHODS

The procedures were performed in 239 consecutive lesions in 160 patients between April 1986 and March 2000. This study excluded emergency cases and repeat angioplasty cases, and included 120 initial and elective cases. Initial and long-term results were compared between the balloon group (n = 29) and the new device group (n = 91).

RESULTS

Lesion success rate was lower in the balloon group (90% vs 100%, p < 0.05), but there were no significant differences in in-hospital results including cardiac death (0% vs 0%), noncardiac death (0% vs 3.3%), Q-wave myocardial infarction (0% vs 2.2%), non-Q wave myocardial infarction (3.4% vs 6.6%), bypass surgery (0% vs 0%) and repeat angioplasty (6.9% vs 1.1%). Quantitative angiography showed significant improvements in minimal lumen diameter (mean 2.17 vs 3.16 mm, p < 0.001) and percentage diameter stenosis (mean 31% vs 13%, p < 0.001) in the new device group after the procedures. The minimum lumen diameter remained larger at 3 (p < 0.001) and 6 months (p < 0.05) in the new device group. Therefore, angiographic restenosis rate was higher in the balloon group (55% vs 21%, p < 0.005). Five-year survival rate showed no significant difference between the groups (75.0% vs 83.8%).

CONCLUSIONS

New devices significantly improved the minimal lumen diameter after angioplasty for unprotected left main trunk disease, and lead to significant improvement of restenosis rate at follow-up.

Troglitazone improves endothelial function and augments renal klotho mRNA expression in Otsuka Long-Evans Tokushima Fatty (OLETF) rats with multiple atherogenic risk factors

Targeted disruption of the klotho gene induces multiple phenotypes characteristic of human aging, including arteriosclerosis, pulmonary emphysema and osteoporosis. Moreover, we previously observed that insufficient klotho expression in mice leads to endothelial dysfunction. In the present study, we used Otsuka Long-Evans Tokushima Fatty (OLETF) rats, which exhibit hypertension, obesity, severe hyperglycemia and hypertriglyceridemia, and are thus considered an animal model of atherogenic disease, to test the effects of oral administration of troglitazone (200 mg/kg) on renal klotho mRNA expression and endothelial function. Systolic blood pressure, body weight, plasma glucose and triglyceride levels were all significantly higher in 30-week-old OLETF rats than in controls (LETO; Long-Evans Tokushima Otsuka) (p<0.05, n=7). In addition, endothelium-dependent relaxation of the aorta in response to 10(-5) M acetylcholine was significantly attenuated in OLETF rats (p<0.05, n=7), as was renal expression of klotho mRNA. Administration of troglitazone for 10 weeks significantly reduced systolic blood pressure, plasma glucose and triglyceride levels in OLETF rats, while augmenting endothelium-dependent aortic relaxation and renal klotho mRNA expression. These findings suggest that troglitazone protects the vascular endothelium against damage caused by the presence of multiple atherogenic factors.

Cytochrome b(6)f mutation specifically affects thermal dissipation of absorbed light energy in Arabidopsis

Light-induced lumenal acidification controls the efficiency of light harvesting by inducing thermal dissipation of excess absorbed light energy in photosystem II. We isolated an Arabidopsis mutant, pgr1 (proton gradient regulation), entirely lacking thermal dissipation, which was observed as little non-photochemical quenching of chlorophyll fluorescence. Map-based cloning showed that pgr1 had a point mutation in petC encoding the Rieske subunit of the cytochrome b(6)f complex. Although the electron transport rate was not affected at low light intensity, it was significantly restricted at high light intensity in pgr1, indicating that the lumenal acidification was not sufficient to induce thermal dissipation. This view was supported by (i) slow de-epoxidation of violaXanthin, which is closely related to lumenal acidification, and (ii) reduced 9-aminoacridine fluorescence quenching. Although lumenal acidification was insufficient to induce thermal dissipation, growth rate was not affected under low light growth conditions in pgr1. These results suggest that thermal dissipation is precisely regulated by lumenal pH to maintain maximum photosynthetic activity. We showed that pgr1 was sensitive to changes in light conditions, demonstrating that maximum activity of the cytochrome b(6)f complex is indispensable for short-term acclimation.

Inhibition of factor Xa suppresses the expression of tissue factor in human monocytes and lipopolysaccharide-induced endotoxemia in rats

BACKGROUND

Activated factor X (FXa) is involved in hemostasis, thrombogenesis, inflammation, and cellular immune response. Tissue factor (TF) is an initiator of blood coagulation. We investigated whether FXa induces TF expression in human peripheral monocytes and whether treatment with FXa inhibitor reduces TF expression in an experimental model of rat endotoxemia.

METHODS

Human peripheral mononuclear cells were used to determine TF expression induced by FXa. Experimental rat endotoxemia was induced by intravenous bolus injection of lipopolysaccharide (LPS). A specific FXa inhibitor, DX-9065a, was administered subcutaneously immediately after LPS injection.

RESULTS

FXa induced TF expression in monocytes without intervention of thrombin and the expression was suppressed by FXa inhibitor. In the experimental model of rat endotoxemia, TF and TF mRNA expression levels in the liver were reduced by DX-9065a. Moreover, administration of DX-9065a suppressed the rise in plasma concentrations of thrombin-antithrombin III complex (TAT) and monocyte chemoattractant protein-1 (MCP-1).

CONCLUSIONS

Our results indicated that FXa can induce TF expression in human peripheral monocytes and that inhibition of FXa reduces TF expression in the liver of rat endotoxemia. These results suggest that FXa is an important factor for TF expression in sepsis.

Linear DNA intermediates of the Tto1 retrotransposon in Gag particles accumulated in stressed tobacco and Arabidopsis thaliana

The active transcription of some plant retrotransposons under diverse stress conditions suggests active transposition. However, transposition has been demonstrated only during tissue/cell culture. To examine whether transposition is activated under conditions other than tissue/cell culture, DNA intermediates for retrotransposition of the tobacco retrotransposon Tto1 were analysed. Using transgenic Arabidopsis callus expressing high levels of Tto1 RNA in a ddm1 hypomethylation mutant background, the existence of extrachromosomal Tto1 linear DNA molecules in a Gag-particle fraction was demonstrated. By combination with ligation-mediated PCR amplification, we detected Tto1 linear DNA molecules in particle fractions from callus and methyl jasmonate-treated leaves of tobacco, but not from non-stressed leaves. Tto1 DNA intermediates could not be detected in the tobacco corolla where Tto1 is expressed. These results indicate that the transcriptional activation of Tto1 by defence-related stresses leads to the synthesis of DNA intermediates, whereas post-transcriptional suppression of Tto1 activity is suggested in the corolla.

Renal involvement induced by human parvovirus B19 infection

In an attempt to clarify the renal involvement induced by human parvovirus B19 (HPB19) infection, we investigated 6 adult patients with transient urinary abnormalities followed by erythema infectiosum. All patients had HPB19-specific IgM antibody and showed mild proteinuria of 0.2-1.2 g/day with or without microscopic hematuria. In 5 patients a decrease of complement was present, and in 2 the circulating immune complex levels were elevated. All patients showed mild or moderate endocapillary proliferation with leukocytic infiltrates in glomeruli and leukocytic infiltrates with edema around interlobular arteries and arterioles. Immunofluorescence microscopy revealed C3c deposits with immunoglobulins along the glomerular capillary walls and in the walls of small arteries and arterioles. Electron microscopic studies showed swelling of the endothelial cells and small electron-dense deposits in mesangium (in all 6 patients) and subendothelium (in 5 of 6 patients). However, HPB19 VP1 and VP2 capsid antigens were not demonstrated in the glomerulus or the vascular wall in any patient. These findings suggest that the renal lesions caused by an immune complex mediated phenomenon would be closely correlated with the HPB19 infection, although the precise mechanism is not entirely clear, and that in adults HPB19 should be thought of as a possible cause of acute postinfectious glomerulonephritis.

Proton relay in a one-dimensional hydrogen-bonded chain composed of water molecules and a squaric acid derivative

The crystal structure of a hydrated crystal of bis(squaryl)biphenyl (BSQB*4H2O), in which two squaric acid moieties are connected with a 4,4'-biphenyl unit, was characterized by the presence of a one-dimensional hydrogen-bonded chain composed of BSQB and water molecules. X-ray crystallographic analysis showed that BSQB exists in a dianion form and that, on average, two of the four water molecules are protonated. The enhanced temperature dependence of the thermal parameters of the oxygen atoms of the water molecules suggested dynamic disorder of the water molecules. The solid-state magic angle spinning deuterium NMR spectrum of BSQB*4D2O revealed that deuterons are exchanged between heavy water molecules and oxonium ions with an exchange rate of ca. 700 Hz around 250 K and that deuterons start to migrate in a hydrogen-bonded cluster of water molecules. Ac dielectric measurements were also used to examine the dynamic process in the hydrated crystal. The dielectric permittivity of the crystal dramatically increased above 250 K with a distinct frequency dependence (epsilon' = 4.7 x 10(4) at 340 K and 1 kHz). The frequency dependence of tan delta at 290 K exhibited a maximum at 3.0 kHz, and this maximum shifted to lower frequencies when the temperature of the crystal decreased. These experimental results suggested that in the one-dimensional hydrogen-bonded chain of BSQB*4H2O a proton relay between oxonium ions and water molecules occurred within a cluster of four water molecules and that the relay was transmitted to the adjacent cluster mediated by the modulation of the negative charge distribution of the BSQB dianion. These phenomena were interpreted as the solitonic migration of the charged domain boundaries along the one-dimensional hydrogen-bonded chain.

DNA ligase IV-deficient cells are more resistant to ionizing radiation in the absence of Ku70: Implications for DNA double-strand break repair

Vertebrate cells have evolved two major pathways for repairing DNA double-strand breaks (DSBs), homologous recombination (HR) and nonhomologous DNA end-joining (NHEJ). To investigate the role of DNA ligase IV (Lig4) in DSB repair, we knocked out the Lig4 gene (LIG4) in the DT40 chicken B-lymphocyte cell line. The LIG4(-/-) cells showed a marked sensitivity to X-rays, bleomycin, and VP-16 and were more x-ray-sensitive in G(1) than late S or G(2)/M, suggesting a critical role of Lig4 in DSB repair by NHEJ. In support of this notion, HR was not impaired in LIG4(-/-) cells. LIG4(-/-) cells were more x-ray-sensitive when compared with KU70(-/-) DT40 cells, particularly at high doses. Strikingly, however, the x-ray sensitivity of KU70(-/-)/LIG4(-/-) double-mutant cells was essentially the same as that of KU70(-/-) cells, showing that Lig4 deficiency has no effect in the absence of Ku. These results indicate that Lig4 is exclusively required for the Ku-dependent NHEJ pathway of DSB repair and that other DNA ligases (I and III) do not substitute for this function. Our data may explain the observed severe phenotype of Lig4-deficient mice as compared with Ku-deficient mice.

A collision tumor composed of adenocarcinoma and malignant lymphoma in the remnant stomach after pancreatoduodenectomy: report of a case

The occurrence of a collision tumor in the stomach, consisting of adenocarcinoma and malignant lymphoma, is extremely rare. We report herein the case of a patient who had undergone a pancreatoduodenectomy for bile duct cancer 5 year earlier, in whom an ulcerating tumor of the remnant stomach developed and grew rapidly within 5 months. Surgical exploration revealed a tumor in the remnant stomach, multiple liver metastases, and multiple lymph node metastases. Total resection of the remnant stomach was performed, and pathological examination revealed a collision tumor consisting of adenocarcinoma and malignant lymphoma. The patient died of liver metastases and lymph node metastases 7 months after his second operation. The coexistence of both adenocarcinoma and malignant lymphoma of the remnant stomach and the etiology of this unusual combination, never previously reported, is discussed.

High-throughput characterization for organic pollutants in environmental waters using a capillary electrophoresis chip

To evaluate organic pollution in water, we did preliminarily studies on high-throughput characterization of organic pollution in water using microchip-based capillary electrophoresis (CE) with laseer-induced fluorescence (LIF) detection. The applied voltage was investigated to control the gated valve injection and CE separation for conventional cross type microchips using a self-made personal computer (PC)-based controller as the voltage supply. We obtained high-throughput data for the reproducible separation of fluorescein isothiocyanate (FITC)-labeled river-water samples using a zwitter-ion based buffer solution to avoid adsorption of the labeled sample onto the channel of a microchip made from quartz glass. We used real samples from the Hino River that flows into Lake Biwa, from ten sampling points and obtained several reproducible peaks in different separation patterns for each sample within 2 min. We successfully demonstrated high-throughput characterization of dissolved organic carbon (DOC) in environmental water using the microchip.

Human liver disease decreases methacrylyl-CoA hydratase and beta-hydroxyisobutyryl-CoA hydrolase activities in valine catabolism

BACKGROUND

Methacrylyl-coenzyme A (MC-CoA) hydratase and beta-hydroxyisobutyryl-coenzyme A (HIB-CoA) hydrolase are key enzymes regulating the toxic concentration of MC-CoA generated in valine catabolism.

MATERIALS AND METHODS

We studied the activities and mRNA expression levels of these enzymes in normal human livers and in human livers with chronic hepatitis, cirrhosis, or hepatocellular carcinoma.

RESULTS

The activities of both enzymes were significantly lower by 36% to 46% in livers with cirrhosis or hepatocellular carcinoma compared with normals, suggesting a decrease in the capability of detoxifying MC-CoA with these diseases. The mRNA levels for both enzymes measured by quantitative polymerase chain reaction were significantly increased in livers with cirrhosis, but were not altered in those with chronic hepatitis or hepatocellular carcinoma when compared with normal livers.

CONCLUSION

Our results suggest that low levels of these enzyme activities in livers with cirrhosis or hepatocellular carcinoma are the result of posttranscriptional regulation in the damaged liver.

Characterization of the RcsC-->YojN-->RcsB phosphorelay signaling pathway involved in capsular synthesis in Escherichia coli

Escherichia coli and other enteric microorganisms produce an extracellular polysaccharide capsule, called colanic acid, under certain environmental conditions. This capsular synthesis is regulated by the RcsC (sensor kinase)-->YojN (phosphotransfer intermediate)-->RcsB (response regulator) phosphorelay signal transduction under certain growth conditions. Nonetheless, little is known about signals that exaggerate the Rcs-system. To gain insight into signals that activate the Rcs-system, here we searched for genes that activate the Rcs-system, provided that those on a multicopy plasmid were introduced into E. coli. We identified several such genes, namely, rcsB, rcsA, djlA, lolA, and ompG. The DjlA, LolA, and OmpG proteins are particularly interesting in that they are all located on the cell surface, where the primary sensor RcsC histidine-kinase is localized. Implications of these findings are discussed with special reference to the mechanism by which RcsC perceives external signals.

A prostaglandin E2 receptor subtype EP1 receptor antagonist (ONO-8711) reduces hyperalgesia, allodynia, and c-fos gene expression in rats with chronic nerve constriction

Chronic constriction injury (CCI) of the sciatic nerve in rats induces persistent mechanical hyperalgesia and allodynia. CCI is widely known as a model of neuropathic pain, and many studies using this model have been reported. Recently, c-fos has been used as a neural marker of pain, and various studies have assessed the relationship between hyperalgesia and c-fos expression in the lumbar spinal cord. In this study, we examined the role of a prostaglandin E2 receptor subtype EP1 receptor antagonist (ONO-8711) in a rat CCI model. EP1 receptor antagonist (EP1-ra) oral administration from day 8 to day 14 significantly reduced hyperalgesia and allodynia in the three pain tests on day 15. EP1-ra treatment from day 8 to 14 also reduced c-fos-positive cells in laminae I-II, III-IV, and V-X compared with saline treatment. A single dose of EP1-ra treatment on day 8 significantly reduced hyperalgesia and allodynia at 1 h and 2 h after administration, but the efficacy was not observed at 24 h. We conclude that EP1-ra treatment may be useful for hyperalgesia and allodynia and that EP1 receptor mechanisms are involved in the maintenance of c-fos gene expression induced by nerve injury.

IMPLICATIONS

We examined whether a prostaglandin E2 receptor subtype EP1 receptor antagonist abrogates neuropathic pain induced by chronic constriction injury model in rats. The EP1 receptor antagonist significantly reduced hyperalgesia, allodynia, and c-fos positive cells. These findings suggested that EP1 receptor antagonists may have a role in treatment of neuropathic pain.

Cytotoxic effects of soluble factor in preeclamptic sera on human trophoblasts

Evidence indicating abnormal biological behavior of trophoblasts has been seen in preeclamptic patients, but the mechanism is still unknown. We have previously shown that endothelial injury and neutrophil activation are induced by certain factors in preeclamptic sera. We investigated the effect of sera from eight preeclamptic and 11 normal pregnant women on cellular proliferation and viability of trophoblasts using 3H-thymidine incorporation and the trypan-blue dye exclusion test, respectively. Five of eight preeclamptic sera, but none of the normal pregnant sera, inhibited 3H-thymidine incorporation. The trypan-blue test revealed the sera reduced cellular viability. Gel permeation showed that the greatest growth-inhibitory activity corresponded to a molecular weight of 50 kDa. The serum-mixing test revealed this permeation and inhibitory preeclamptic sera suppressed the growth-promoting activity of normal pregnant sera in a dose-dependent manner. These results suggested the presence of certain factors in some preeclamptic sera that can affect cellular behavior of human trophoblasts.

Opioid action on respiratory neuron activity of the isolated respiratory network in newborn rats

BACKGROUND

Underlying mechanisms behind opioid-induced respiratory depression are not fully understood. The authors investigated changes in burst rate, intraburst firing frequency, membrane properties, as well as presynaptic and postsynaptic events of respiratory neurons in the isolated brainstem after administration of opioid receptor agonists.

METHODS

Newborn rat brainstem-spinal cord preparations were used and superfused with mu-, kappa-, and delta-opioid receptor agonists. Whole cell recordings were performed from three major classes of respiratory neurons (inspiratory, preinspiratory, and expiratory).

RESULTS

Mu- and kappa-opioid receptor agonists reduced the spontaneous burst activity of inspiratory neurons and the C4 nerve activity. Forty-two percent of the inspiratory neurons were hyperpolarized and decreased in membrane resistance during opioid-induced respiratory depression. Furthermore, under synaptic block by tetrodotoxin perfusion, similar changes of inspiratory neuronal membrane properties occurred after application of mu- and kappa-opioid receptor agonists. In contrast, resting membrane potential and membrane resistance of preinspiratory and majority of expiratory neurons were unchanged by opioid receptor agonists, even during tetrodotoxin perfusion. Simultaneous recordings of inspiratory and preinspiratory neuronal activities confirmed the selective inhibition of inspiratory neurons caused by mu- and kappa-opioid receptor agonists. Application of opioids reduced the slope of rising of excitatory postsynaptic potentials evoked by contralateral medulla stimulation, resulting in a prolongation of the latency of successive first action potential responses.

CONCLUSIONS

Mu- and kappa-opioid receptor agonists caused reduction of final motor outputs by mainly inhibiting medullary inspiratory neuron network. This inhibition of inspiratory neurons seems to be a result of both a presynaptic and postsynaptic inhibition. The central respiratory rhythm as reflected by the preinspiratory neuron burst rate was essentially unaltered by the agonists.

Ablation of XRCC2/3 transforms immunoglobulin V gene conversion into somatic hypermutation

After gene rearrangement, immunoglobulin V genes are further diversified by either somatic hypermutation or gene conversion. Hypermutation (in man and mouse) occurs by the fixation of individual, non-templated nucleotide substitutions. Gene conversion (in chicken) is templated by a set of upstream V pseudogenes. Here we show that if the RAD51 paralogues XRCC2, XRCC3 or RAD51B are ablated the pattern of diversification of the immunoglobulin V gene in the chicken DT40 B-cell lymphoma line exhibits a marked shift from one of gene conversion to one of somatic hypermutation. Non-templated, single-nucleotide substitutions are incorporated at high frequency specifically into the V domain, largely at G/C and with a marked hotspot preference. These mutant DT40 cell lines provide a tractable model for the genetic dissection of immunoglobulin hypermutation and the results support the idea that gene conversion and somatic hypermutation constitute distinct pathways for processing a common lesion in the immunoglobulin V gene. The marked induction of somatic hypermutation that is achieved by ablating the RAD51 paralogues is probably a consequence of modifying the recombination-mediated repair of such initiating lesions.

Schwann cell myelination occurred without basal lamina formation in laminin alpha2 chain-null mutant (dy3K/dy3K) mice

The laminin alpha2 chain is a major component of basal lamina in both skeletal muscle and the peripheral nervous system. Laminin alpha2 chain deficiency causes merosin-deficient congenital muscular dystrophy, which affects not only skeletal muscles, but also the peripheral and central nervous systems. It has been reported that the formation of basal lamina is required for myelination in the peripheral nervous system. In fact, the spinal root of dystrophic mice (dy/dy mice), whose laminin alpha2 chain expression is greatly reduced, shows lack of basal lamina and clusters of naked axons. To investigate the role of laminin alpha2 chain and basal lamina in vivo, we examined the peripheral nervous system of dy3K/dy3K mice, which are null mutants of laminin alpha2 chain. The results indicate the presence of myelination although Schwann cells lacked basal lamina in the spinal roots of dy3K/dy3K mice, suggesting that basal lamina is not an absolute requirement for myelination in vivo. Immunohistochemically, the expression of laminin alpha4 chain was increased and laminin alpha5 chain was preserved in the endoneurium of the spinal root. Laminin alpha4 and alpha5 chains may play the critical role in myelination instead of laminin alpha2 chain in dy3K/dy3K mice. In addition, the motor conduction velocity of the sciatic nerve was significantly reduced compared with that of wild-type littermate. This reduction in conduction velocity may be due to small axon diameter, thin myelin sheath and the patchy disruption of the basal lamina of the nodes of Ranvier in dy3K/dy3K mice.

Ionization of dichlorophenols for their analysis by capillary electrophoresis-mass spectrometry

In order to develop an advanced analytical method using capillary electrophoresis (CE) for non-volatile environmental pollutants such as endocrine disruptors, combination with mass spectrometry (MS) is necessary for their identification. We chose dichlorophenols (DCPs) as test samples because one of their isomers, 2,4-DCP, is suspected to have endocrine disrupting effects. A preliminary study on their separation by CE-MS was performed using a laboratory-made electrospray ionization (ESI) interface. For the effective ionization of 2,4-DCP at the

Homologous DNA recombination in vertebrate cells

The RAD52 epistasis group genes are involved in homologous DNA recombination, and their primary structures are conserved from yeast to humans. Although biochemical studies have suggested that the fundamental mechanism of homologous DNA recombination is conserved from yeast to mammals, recent studies of vertebrate cells deficient in genes of the RAD52 epistasis group reveal that the role of each protein is not necessarily the same as that of the corresponding yeast gene product. This review addresses the roles and mechanisms of homologous recombination-mediated repair with a special emphasis on differences between yeast and vertebrate cells.

T lymphocyte activation and restenosis after percutaneous transluminal coronary angioplasty

We investigated the relation between the activation of T lymphocytes and the occurrence of restenosis after percutaneous transluminal coronary angioplasty (PTCA) in 10 stable angina patients. Recent studies have suggested that PTCA causes an inflammatory response, which may affect restenosis after angioplasty. Soluble interleukin-2 receptor (sIL-2R) is a useful marker to evaluate the activation of T lymphocytes. sIL-2R was measured before and 2 h after successful PTCA, and 3-month follow-up coronary angiography was done to observe restenosis. Four of 10 patients showed restenosis. The restenosis group of 4 patients had a higher level of sIL-2R after PTCA than the no-restenosis group of 6 patients (495 vs. 274 U/ml, p < 0.01). This study suggests that sIL-2R may offer prognostic information after elective PTCA and identify a subgroup of patients at high risk for clinical restenosis in a few months.

Long axis excursion in aortic stenosis

OBJECTIVES

To examine long axis excursion in patients with all grades of aortic stenosis and preserved transverse systolic function, and to compare long axis excursion in symptomatic with that in asymptomatic severe aortic stenosis.

DESIGN

Prospective comparative study.

SETTING

Regional cardiothoracic centre.

PATIENTS

78 patients with all grades of aortic stenosis and normal fractional shortening and ejection fraction were studied. There were two comparison groups, 10 age matched normal subjects and 14 patients with aortic stenosis and fractional shortening < 26%.

METHODS

Aortic valve function and left ventricular mass were assessed echocardiographically. M mode measurements of long axis excursion at the septal and lateral sides of the mitral annulus were taken.

RESULTS

There were significant differences between the groups in long axis excursion at both the septal (p < 0.0001) and lateral sides of the mitral annulus (p = 0.002 by analysis of variance). Long axis excursion was independently related to both left ventricular mass index (p = 0.001) and the grade of aortic stenosis (p = 0.002). Comparing patients with severe aortic stenosis with and without symptoms, there were significant differences in effective orifice area (p = 0.02 ) and long axis excursion at the lateral side of the mitral annulus (p = 0.04), but not in fractional shortening, ejection fraction, or peak or mean pressure difference.

CONCLUSION

In patients with aortic stenosis, long axis excursion is reduced even in the presence of normal fractional shortening or ejection fraction. It is lower in patients with symptomatic compared with asymptomatic severe aortic stenosis and may be of use in predicting the onset of symptoms.

The role of extended radical operation for pancreatic cancer

BACKGROUND/AIMS

To clarify the indication of extended operation for pancreatic carcinoma, a clinical study was carried out.

METHODOLOGY

From July 1981 to 1999, 196 of 307 (63.8%) patients with pancreatic carcinoma underwent resection of the tumor. Portal vein resection was performed in 145 of these 196 (74.0%) resected cases. The postoperative survival rate was studied according to the operative and histopathological findings.

RESULTS

In spite of the aggressive surgery, there was no patient who survived over 3 years after operation in the group carcinoma-positive on the surgical margins. Patients who survived over 3 years postoperatively were observed in the group of carcinoma-free surgical margins.

CONCLUSIONS

The most important indication of extended operation combined with portal vein resection for pancreatic cancer is to obtain surgical cancer-free margins. There is no indication of extended operation for cases in which surgical margins will become cancer-positive, if such an operation is employed.

Gene therapy for pancreatic cancer

Despite improvements in surgical care and locoregional therapy, the prognosis of patients with pancreatic cancer has seen little improvement over the last several decades. It is difficult to diagnose pancreatic cancer at its earliest stages when it is amenable to cure by surgical resection because it is too small to produce symptoms in the affected patient. Recent improvements in radiographic modalities aimed at earlier detection and extent of cancer spread have enabled the clinician to provide the most efficacious treatment regimen possible. Nevertheless, pancreatic cancer is very aggressive locally and frequently metastasizes to the liver and peritoneum. New strategies are necessary to treat pancreatic cancer and gene therapy offers hope in this regard. Many studies have revealed the promise of gene therapy in the treatment of pancreatic cancer in rodent models. Early clinical trials are ongoing to evaluate the success of these gene therapy regimens in humans. In this article we review the gene therapy strategies currently employed in the fight against pancreatic cancer, including antisense strategies, gene-directed prodrug activation therapy, promoter gene strategies, and oncolytic viral therapy.

Clinical usefulness of the immunostaining of the tumor markers in pancreatic cancer

The effect of the rapid immunostaining of gastrointestinal cancer-associated antigens, CA19-9, CEA, DUPAN2, and CA50 was discussed for intraoperative pathological diagnosis of pancreatic cancer. The method can be completed in only 13 minutes with microwave irradiation to accelerate the incubation of the primary antibody. Only 3 seconds of irradiation at 500 W for fresh-frozen sections produced specific antigen staining of greater intensity than that obtained with longer incubation by the conventional method. Preservation of the tissue structure was satisfactory with minimal nonspecific background staining enabling us to diagnose the intrapancreatic spread of cancer. This method was also applied to intraoperative peritoneal washing cytology. As with frozen section biopsy, the sensitivity of intraoperative cytology is greater than by the conventional staining method, which is able to achieve more precise staging of pancreatic cancers. Our rapid immunoperoxidase staining method on the cryostat section of pancreatic biopsy specimens and on cytology samples provides important information to determine an appropriate operative approach for pancreatic cancer.