Cyclosporin A inhibits leukotriene production in intact RBL-1 cells without inhibiting leukotriene biosynthetic enzymes

The effects of cyclosporin A (CSA) on arachidonic acid (AA) metabolism were investigated in intact rat basophilic leukemia-1 (RBL-1) cells and cell lysates. Calcium ionophore (A23187)-stimulated synthesis of cysteinyl leukotrienes (LTC4, LTD4, and LTE4), LTB4, and 5-hydroxyeicosatetraenoic acid (5-HETE) in intact cells in the absence or presence of CSA was measured by reversed-phase high-performance liquid chromatography (HPLC). CSA inhibited the production of cysteinyl LTs, LTB4, and 5-HETE in intact cells in a dose-dependent manner. The synthesis of cysteinyl LTs, LTB4, and 5-HETE was also measured after the incubation of cell lysates with free AA in the absence or presence of CSA. CSA did not inhibit synthesis of cysteinyl LTs, but rather stimulated production of LTB4 and 5-HETE in cell lysate. A23187-stimulated release of incorporated [3H]AA from intact cells was not inhibited by CSA. CSA did not inhibit the synthesis of cysteinyl LTs and LTB4 when cells incubated with LTA4 as the substrate. These results indicate that the inhibitory effects of CSA on the synthesis of LTs and 5-HETE in intact cells are attributable to a modulatory action on a step in the series of intracellular events that includes the activation of 5-lipoxygenase, which are initiated by Ca2+ influx and end in the release of metabolites from the cell membrane, rather than to a direct inhibitory action on enzymes in the LT biosynthetic pathway.

Neoadjuvant chemotherapy with etoposide, leucovorin, 5-fluorouracil and cisplatin for advanced esophageal squamous cell carcinoma

Eighteen patients with invasive periadventitial tissue (T4) or distant lymph node metastatic (M1,LYM) squamous cell carcinoma were entered into a pilot study of neoadjuvant chemotherapy with etoposide (50 mg/m2/day, days 1-5), leucovorin (30 mg/body/day, days 2-5), 5-fluorouracil (5-FU; 400 mg/m2/day, days 2-5) and cisplatin (100 mg/m2/day, day 1) (ELFP). The overall response rate was 56%. The response rates in the T4 tumor and M1,LYM patients were 56 and 50%, respectively. Radical esophagectomies were performed on six of 17 patients who had completely recovered from the chemotherapy, a resectability of 35%. Histologically, the primary tumor was moderately to slightly effective, and the lymph nodes markedly to moderately effective. Histologic responses in the lymph nodes were different from those in the primary tumors and in each node. There were four chemo-surgically related deaths. Median survival times in responding and non-responding patients were nine and three months, respectively. In conclusion, neoadjuvant chemotherapy with ELFP appears to be effective against esophageal squamous cell cancer with periadventitial tissue invasion or distant lymph node metastasis. Chemo-surgically related deaths were however, 22%, showing neoadjuvant chemotherapy to necessitate extremely careful attention to the medical and surgical management of patients.

Dependence of frequency of homologous recombination on the homology length

The frequency of homologous recombination is believed to be a linear function of the length (N bp) of homology between DNAs. Here, the N intercept is believed to be determined by a threshold length below which some physical constraint is effective. In the mammalian gene targeting systems, however, the frequency depends more steeply than linearly on the homology length. To explain both the linear dependence and the steeper dependence, we propose a model where the branch point of a reaction intermediate is assumed to "walk randomly" along the homologous region until it is processed. The intermediate is assumed to be destroyed if the branch point ever reaches either end of the homology. In this model, the length dependence is governed by a parameter, h, which is defined as efficiency of processing of the intermediate and reflects unlikelihood of the destruction at either end of the homology. We find that the frequency is proportional to N3 for smaller N and is a linear function of N for larger N. Where the shift from the N3 dependence to the linear dependence takes place is determined by the parameter h. The range of N showing the N3 dependence becomes narrower as h becomes larger. The dependence steeper than linear dependence, which is observed not only in the mammalian gene targeting system but also in bacteriophage T4, Escherichia coli and yeast systems, agrees well with the predicted N3 dependence. The N intercept is determined not by physical (or structural) constraints but only by the parameter h in this model.

Central and reflex neural control of genioglossus in subjects who underwent laryngectomy

Inspiratory activation of the genioglossus (GG) may occur by central drive or as a reflex to negative airway pressure. To distinguish between these, we studied seven laryngectomy patients who breathe via tracheal stomas. Negative pressure stimuli (-15 and -25 cmH2O for 500 ms) were applied 1) at functional residual capacity and 2) during early inspiration via (i) the upper airway (UA) and (ii) the tracheal stoma. Intraoral surface GG electromyogram was quantified, as described previously (R. L. Horner, J. A. Innes, K. Murphy, and A. Guz, J. Physiol. Lond. 436: 15-29, 1991). Phasic GG activity was also measured from an integrated electromyogram during spontaneous and inspiratory loaded breathing. Reflex GG activation occurred with negative UA pressure both at functional residual capacity and during inspiration (P < 0.001), but pressure stimuli at the stoma caused no significant activation (P = 0.07). Phasic inspiratory activation occurred in four patients at rest and in all seven patients during inspiratory loading (P < 0.02). These patients demonstrate 1) reflex activation of the GG by negative UA pressure without airflow or respiratory effort and 2) central inspiratory GG activation that is not mediated by negative airway pressure.

Gait disturbance of patients with vascular and Alzheimer-type dementias

The gaits of 15 patients with senile dementia of the Alzheimer type and 15 with vascular dementia were compared with those of 15 healthy control subjects. Patients with senile dementia showed significantly slower velocity and shorter step length than the healthy controls, and those with vascular dementia exhibited a reduction on these two variables relative to patients with senile dementia of the Alzheimer type.

Chronic effect of losartan in a murine model of dilated cardiomyopathy: comparison with captopril

The long-term effects of losartan, an angiotensin II subtype-I receptor antagonist, were compared with those of captopril in a murine model of dilated cardiomyopathy caused by encephalomyocarditis virus. Four weeks after viral inoculation, 42 DBA/2 mice were given oral losartan 1.2 mg/kg/day (n = 8), 12 mg/kg/day (n = 8) or 60 mg/kg/day (n = 8) or captopril 7.5 mg/kg/day (n = 8) in drinking water or distilled water (n = 10). Mice were killed at the end of the 12-wk treatment period. Heart weight, left ventricular thickness, left ventricular cavity dimension and myocardial fiber diameter were significantly lower in mice given losartan 60 mg/kg as compared with the infected untreated group. Captopril had a similar effect on all parameters. The pathologic score of cardiac fibrosis was significantly lower in the mice treated with captopril but was not reduced in the mice treated with losartan. Moreover, as compared with the age- and sex-matched normal mice, cardiac mass and myocardial fiber diameter were significantly lower in normal mice treated with losartan 60 mg/kg. This study suggests that long-term treatment with losartan may prevent thickening of left ventricular wall and cavity dimension in dilated cardiomyopathy caused by encephalomyocarditis virus. The potency, and perhaps the efficacy, of losartan appear to be less than those of captopril.

ATP sparing effect of isoflurane during ischaemia and reperfusion of the canine heart

Sustained dysfunction of myocardial contractility after short periods of coronary artery occlusion and reperfusion has been termed "stunned myocardium". Isoflurane may improve the recovery of regional myocardial contractility in stunned myocardium. The purpose of the present study was to determine if isoflurane prevents depletion of high energy phosphates after myocardial ischaemia-reperfusion and if the reduction in cardiac work during isoflurane anaesthesia contributes to the preservation of high energy phosphate metabolism in an acute canine model. Mongrel dogs were allocated to one of three groups: controls, anaesthetized with urethane and chloralose; ISO group, isoflurane administered before ischaemia; and ISOc group, heart rate and mean arterial pressure controlled to approximately match baseline values. The left anterior descending (LAD) coronary artery was occluded for 15 min and then reperfused for 60 min during 1.5% end-tidal isoflurane anaesthesia. Full thickness samples of myocardium were obtained from the reperfused area (supplied by the LAD) and the non-ischaemic area (supplied by the left circumflex coronary artery). The concentrations of adenosine monophosphate (AMP), adenosine diphosphate (ADP), adenosine triphosphate (ATP), creatine phosphate (CP) and lactate in the endocardial portion of the myocardium were measured. Arterial pressure, aortic flow in the ascending aorta and rate-pressure product decreased significantly after isoflurane. Although the concentration of ATP of the reperfused area in the control group showed a significant reduction 60 min after reperfusion, the ISO and ISOc groups had significantly greater concentrations. Isoflurane anaesthesia maintained myocardial high energy phosphate metabolism in reperfused myocardium. We conclude that the reduction in cardiac work played only a minor role in the ATP-sparing effect of isoflurane.

Intravenous administration of vancomycin is ineffective against bacteremia following tooth extraction

The incidence of transient bacteremia after tooth extraction without antimicrobial prophylaxis has been reported was high as 69.2%; that with intravenous ampicillin as 4.2% (1, 2). Currently, we tested a regime of vancomycin that was recommended by the American Heart Association as prophylaxis for oral surgery patients who were allergic to penicillin and evaluated its effectiveness. Before the surgical procedures, we started an intravenous drip infusion of vancomycin. Ten of 26 patients became blood culture positive (38.5%). Seventeen strains of bacteria were isolated. The Minimum Inhibitory Concentrations (MICs) of vancomycin were lower than 3.13 micrograms/ml, with just one exception.

Effect of losartan, an AT1 selective angiotensin II receptor antagonist, on isoproterenol-induced cardiac ornithine decarboxylase activity

Ornithine decarboxylase (ODC,EC 4.1.1.7), a rate-limiting enzyme in polyamine biosynthesis, is known to be induced by a beta-adrenoceptor agonist, isoproterenol (ISO). ODC activity and cardiac polyamine content are considered to be correlated with ISO-induced cardiac hypertrophy in rat hearts. To determine whether ISO-induced cardiac ODC activity is mediated through the renin-angiotensin system, especially at the AT1-receptor, we used a nonpeptide AT1 receptor antagonist, losartan, in this study. Losartan (10 mg/kg) suppressed both heart ODC and polyamine contents in ISO-treated rats. Although metoprolol (a selective beta-adrenoceptor antagonist) totally suppressed ODC activity, these results suggest that ISO-stimulated cardiac ODC activity may be regulated through beta 2-adrenoceptors coupled with AT1 receptors in rats.

Colonic mucosal hemodynamics and tissue oxygenation in patients with ulcerative colitis: investigation by organ reflectance spectrophotometry

Colonic mucosal hemodynamics were investigated at the rectosigmoidal region of the colon in 46 patients with ulcerative colitis and in 18 normal subjects by organ reflectance spectrophotometry under colonoscopy. The value for the index of mucosal hemoglobin concentration (IHb) was significantly higher, and value for the index of mucosal hemoglobin oxygen saturation (ISO2) was significantly lower in patients with active ulcerative colitis than values in the normal controls or in patients with inactive ulcerative colitis. The results indicate mucosal congestion and hypoxemia in patients with active ulcerative colitis. The changes in IHb and ISO2 correlated well with the severity of ulcerative colitis scored by endoscopic findings and with the number of infiltrating inflammatory cells in the mucosa analyzed histologically in biopsy samples. In conclusion, the colonic mucosal microcirculation in patients with active ulcerative colitis was disturbed and showed congestion and hypoxemia. The analysis of hemodynamic changes may be helpful for assessing the activity of ulcerative colitis.

Inhibition of leukotriene production by FK506 in rat basophilic leukemia-1 cells

We investigated the inhibitory action of FK506 (0.0005-5 micrograms/ml) on the metabolism of arachidonate 5-lipoxygenase in rat basophilic leukemia-1 cells. Cells were stimulated with A23187 (10(-5) mol/l) for 15 min in the absence or presence of various concentrations of FK506. Arachidonate 5-lipoxygenase metabolites, peptide leukotrienes (LTs), leukotriene B4 (LTB4) and 5-hydroxyeicosatetraenoic acid (5-HETE) were measured by high-performance liquid chromatography. FK506 inhibited A23187-stimulated production of peptide LTs, LTB4 and 5-HETE in intact cells by up to 77, 73 and 60%, respectively. Phospholipase A2 activity, measured by the release of 3H-arachidonic acid (AA), was not significantly inhibited by FK506. The synthesis of peptide LTs and LTB4 was not inhibited by FK506 when leukotriene A4-free acid was added to the culture medium. The synthesis of peptide LTs, LTB4 and 5-HETE was not affected by FK506 in a cell lysate study using AA as the substrate. These results indicate that FK506 inhibits the production of peptide LTs, LTB4 and 5-HETE by inhibiting 5-lipoxygenase activity in intact cells. The inhibition is not a direct action on 5-lipoxygenase but results from the activating processes of this enzyme.

Selfish behavior of restriction-modification systems

Plasmids carrying gene pairs encoding type II DNA restriction endonucleases and their cognate modification enzymes were shown to have increased stability in Escherichia coli. The descendants of cells that had lost these genes appeared unable to modify a sufficient number of recognition sites in their chromosomes to protect them from lethal attack by the remaining restriction enzyme molecules. The capacity of these genes to act as a selfish symbiont is likely to have contributed to the evolution of restriction-modification gene pairs.

Age-related changes in natural and fast walking

Age-related changes in the relation between natural and fast walking were investigated for 69 healthy women aged 21 to 88 years. The ratio (fast/natural) of both walking velocity and cadence declined significantly across age groups.

Sleep disturbance in elderly patients with cognitive impairment, decreased daily activity and periventricular white matter lesions

We investigated how sleep disturbance is correlated with brain lesions, cognitive impairment and decreased daily activity (ADL). Two hundred and four chronically ill patients including patients with vascular dementia were classified into eight groups based on cognitive function, ADL and grades of PVL (periventricular lucency) as shown by computerized tomography. Visual monitoring of the sleep/wake state was performed hourly for 14 consecutive days and the daytime sleep hours and the nighttime sleep hours were determined based on detected disturbances in the sleep/wake pattern. Whether any specific infarcted regions were correlated with sleep disturbance was also evaluated. We found that daytime sleep hours were increased and nighttime sleep hours were decreased by three single factors: cognitive impairment, decreased ADL and the severe grade of PVL. As for an interactive effect of the two factors, daytime sleep hours were increased by dementia with decreased ADL (independent of PVL) and increased by decreased ADL with the severe grade of PVL (independent of dementia). Although three factors affected sleep independently, ADL has an interactive effect on sleep with dementia and with PVL. No specific cortical regions related to sleep disturbance were found.

Western blot analysis of rat pituitary antigens recognized by human antipituitary antibodies

Antipituitary antibodies have been reported to exist in sera of patients with autoimmune endocrine disorders. In order to investigate the pituitary antigens recognized by antipituitary antibodies, we studied the autoantigens in rat pituitary membrane and cytosolic fractions recognized by human antipituitary antibodies and anti-human pituitary hormone antibodies. Sera from 6 patients which showed positive antipituitary antibodies by immunofluorescence methods were studied. Each serum identified some proteins with 14.5, 22, 47, 49, 65, 84 and 97.5 kDa. Anti-GH antibodies and anti-PRL antibodies identified a positive band with 22 kDa, suggesting that anti-GH and anti-PRL antibodies may be present in patients' sera. These results indicate that Western blot analysis of rat pituitary antigens recognized by human antipituitary antibodies is a useful method to elucidate the pathophysiology of autoimmune endocrine disorders.

Myocardial uptake of an iodinated branched fatty acid analog, assessed by SPECT, may detect metabolic derangement of the myocardium in diabetic patients with coronary heart disease

The clinical implications of single-photon emission computed tomography using both a beta-methyl-branched fatty acid analog, 123I-15-(p-iodophenyl)-3-methyl-pentadecanoic acid (BMIPP), and thallium-201 (201Tl) were assessed in 30 patients with myocardial infarction (MI), 8 diabetics, 4 patients with impaired glucose tolerance, and 18 nondiabetic patients. Discordant decreases in BMIPP uptake, as compared with 201Tl uptake, in diabetic patients were significantly (p < 0.01) more frequent than in nondiabetic patients. The left ventricular (LV) ejection fraction in diabetics was significantly (p < 0.05) reduced and the LV diastolic dimension was significantly increased (p < 0.01), as compared with those in nondiabetic subjects. Analysis of peripheral blood showed no significant differences among the three test groups in metabolic abnormality. A discordant decrease in BMIPP uptake, as compared with Tl uptake, in cardiac tomography may indicate a metabolic derangement of the myocardium in diabetic patients with MI.

Endogenous nitric oxide modulates ethanol-induced gastric mucosal injury in rats

BACKGROUND/AIMS

Endothelium-derived relaxing factor regulates vascular tone via vasodilation. The relative contribution of endogenous nitric oxide to the pathophysiology of ethanol-induced gastric mucosal microcirculatory disturbances was investigated in anesthetized rats.

METHODS

Macroscopic and microscopic gastric mucosal damage and gastric mucosal hemodynamics including blood flow and hemoglobin oxygen saturation (ISO2) were assessed by pretreatment with a specific NO synthase inhibitor, N omega-nitro-L-arginine (L-NNA), before and after intragastric administration of ethanol.

RESULTS

Pretreatment with L-NNA significantly increased macroscopic (7.7-fold) and microscopic damage caused by 30% ethanol. Concurrent administration of L-arginine, but not D-arginine, significantly reduced the increase in mucosal damage. Similar results were obtained with 60% ethanol. Pretreatment with L-NNA decreased both mucosal blood flow and ISO2 in the basal period and enhanced decreases in both mucosal blood flow (2.7-fold) and ISO2 (4.3-fold) induced by 30% ethanol compared with controls. Concurrent administration of L-arginine, but not D-arginine, significantly inhibited the effect of L-NNA on blood flow and ISO2 in the basal period as well as after intragastric administration of 30% ethanol.

CONCLUSIONS

Endogenous NO modulates ethanol-induced gastric mucosal injury through the regulation of gastric mucosal microcirculation.

Thyrotropin-induced hydrogen peroxide production in FRTL-5 thyroid cells is mediated not by adenosine 3',5'-monophosphate, but by Ca2+ signaling followed by phospholipase-A2 activation and potentiated by an adenosine derivative

The production of hydrogen peroxide (H2O2) as an essential process for iodide organification is a key reaction in TSH-induced thyroid hormone synthesis. Here we characterize the signal transduction pathway involved in TSH-induced H2O2 production in FRTL-5 thyroid cells. At higher than 1 nM TSH, N6-(L-2-phenylisopropyl)adenosine (PIA), an adenosine receptor agonist having, by itself, no influence on H2O2 generation, potentiated this TSH action, whereas the TSH increase and PIA addition reduced cAMP accumulation. RO 20-1724, a phosphodiesterase inhibitor, amplified the TSH-induced cAMP accumulation, but did not change H2O2 generation in the whole range of TSH used. Ca(2+)-mobilizing agonists, GTP and ATP, also induced H2O2 production without stimulating cAMP accumulation. Chelation of intracellular Ca2+ markedly inhibited the TSH action, but intracellular Ca2+ increases by either thapsigargin or ionomycin mimicking it. All of the findings show the participation of Ca2+, but not cAMP, in the action of TSH. Desensitization of protein kinase-C (PKC) did not influence the receptor-mediated H2O2 production, suggesting the reduced importance of PKC activation compared to Ca2+ signaling to the reaction. A rise in intracellular Ca2+ independent of receptor activation also induced H2O2 production as well as arachidonate release, and both were potentiated by PIA. In addition, inhibitors of phospholipase-A2 and the arachidonate metabolic pathway depressed H2O2 generation, suggesting the participation of an arachidonate cascade in the Ca(2+)-dependent H2O2 production. Lipoxygenase inhibitors depressed the Ca2+ action without influencing arachidonate release, suggesting the involvement of a lipoxygenase product(s) of arachidonate in the Ca(2+)-signaling mechanism. In conclusion, in FRTL-5 cells, TSH-induced H2O2 production is mediated not by cAMP, but by the phospholipase-C/Ca2+ cascade, possibly followed by the Ca(2+)-dependent phospholipase-A2/arachidonate cascade. PIA amplifies TSH-induced H2O2 production at the steps of phospholipase-C and phospholipase-A2 activation in a pertussis toxin-sensitive manner.

An immunohistochemical and ultrastructural study of vasomotor nerves in the microvasculature of human dental pulp

Immunohistochemical methods for S-100 protein and neurone-specific enolase showed two types of nerve endings around the pulp microvasculature: the free endings, which comprise the major neural component and are distributed in all types of microvessel such as arterioles, venules and capillaries; and the varicose endings. The varicose ending was a less frequent, minor component observed only in the arterioles. Both immunohistochemical and ultrastructural observations confirmed that the varicose endings were the terminal axons of efferent vasomotor nerves. Further extensive ultrastructural examinations on the vasomotor nerves added the following new findings to our previous reports. Vasomotor nerves sometimes ramified into more than two terminal axons around arterioles, and most of these ramified axons ended in the adventitia-media junction of the arteriolar wall; however, nerve endings occasionally penetrated into the media. These findings suggest an intimate structural association between vasomotor nerves and arterioles in regulating the arteriolar microcirculation in human dental pulp by stimulating smooth-muscle cells not only of the outermost but also of the inner layers. Furthermore, the deep penetration of terminal axons into the arteriolar wall seems to provide effective regulation of pulpal blood flow under physiological and pathological conditions.

Evidence for conservative (two-progeny) DNA double-strand break repair

The double-strand break repair models for homologous recombination propose that a double-strand break in a duplex DNA segment is repaired by gene conversion copying a homologous DNA segment. This is a type of conservative recombination, or two-progeny recombination, which generates two duplex DNA segments from two duplex DNA segments. Transformation with a plasmid carrying a double-strand gap and an intact homologous DNA segment resulted in products expected from such conservative (two-progeny) repair in Escherichia coli cells with active E. coli RecE pathway (recBC sbcA) or with active bacteriophage lambda Red pathway. Apparently conservative double-strand break repair, however, might result from successive events of nonconservative recombination, or one-progeny recombination, which generates only one recombinant duplex DNA segment from two segments, involving multiple plasmid molecules. Contribution of such intermolecular recombination was evaluated by transformation with a mixture of two isogenic parental plasmids marked with a restriction site polymorphism. Most of the gap repair products were from intramolecular and, therefore, conservative (two-progeny) reaction under the conditions chosen. Most were conservative even in the absence of RecA protein. The double-strand gap repair reaction was not affected by inversion of the unidirectional replication origin on the plasmid. These results demonstrate the presence of the conservative (two-progeny) double-strand break repair mechanism. These experiments do not rule out the occurrence of nonconservative (one-progeny) recombination since we set up experimental conditions that should favor detection of conservative (two-progeny) recombination.

New human oral squamous carcinoma cell line and its tumorigenic subline producing granulocyte colony-stimulating factor

A new human carcinoma cell line, MISK81-5, was established from a metastatic lymph node of oral squamous cell carcinoma. Immunocytochemical and ultrastructural observations revealed an obvious epithelial origin of the cell line. Chromosome analysis revealed a hypertriploid karyotype with numerical and structural anomalies. MISK81-5 cells could form a tumor mass in the subcutaneous tissue of recipient BALB/c athymic mice only when coinjected with Matrigel. A stem cell assay revealed that conditioned medium (CM) of MISK81-5 contained granulocyte colony-stimulating factor (G-CSF) or interleukin-6 activity. Quantitation by ELISA disclosed a higher concentration of G-CSF in the CM of MISK81-5 than in the CM of other squamous and gastric carcinoma cell lines. The sMISK, that was derived from MISK81-5 as a subpopulation of the cell line having higher tumorigenicity, also showed a similar hematopoietic stimulating activity to that of MISK81-5. These characteristics of the MISK81-5 cell line and its subpopulation, sMISK will be useful for studying the biological behavior of oral squamous cell carcinomas and its relation to hematopoietic stimulating factors.