Store-refilling involves both L-type calcium channels and reverse-mode sodium-calcium exchange in airway smooth muscle

The aim of the present study was to examine the relative contributions to store-refilling of the two following voltage-regulated calcium ion influx pathways: 1) L-type-Ca(2+) channels; and 2) the reverse-mode of the sodium-calcium exchanger (NCX). Successive acetylcholine-induced contractions, triggered in bovine tracheal smooth muscle strips, were measured to determine the effect of intervention on contractions as an indication of the extent of store-refilling. Pre-treating the tissues with cromakalim significantly reduced the magnitude of successive contractions. Zero-Ca(2+) bathing media abolished the contractions, an effect that was completely reversed upon reintroduction of Ca(2+). Inhibition of L-type Ca(2+) channels, with nifedipine, significantly reduced the magnitude of the contractions. Similarly, inhibition of the reverse-mode of the NCX, with KB-R7943, significantly reduced the magnitude of the contractions. However, neither nifedipine nor KB-R7943 alone reduced contractions to the same extent as observed under zero-Ca(2+) conditions. Concurrent treatment with nifedipine and KB-R7943 almost abolished successive contractions. Furthermore, concurrent treatment with nifedipine and zero-Na(+) bathing media displayed a significantly greater effect than nifedipine alone. Probing the expression of NCX1 isoforms by Western blotting revealed the presence of three bands of 160, 120 and 110 kDa. The 120- and 110-kDa bands were identified as variably spliced NCX isoforms, NCX1.1 and NCX1.3, respectively. Taken together, these data suggest that influx of calcium ions through both L-type calcium channels and the reverse-mode of the sodium-calcium exchanger is necessary for complete store-refilling in airway smooth muscle.

Reduction of ferricytochrome c by tyrosyltyrosylphenylalanine

Cytochrome c (cyt c) was reduced by a tyrosine-containing peptide, tyrosyltyrosylphenylalanine (TyrTyrPhe), at pH 6.0-8.0, while tyrosinol or tyrosyltyrosine (TyrTyr) could not reduce cyt c effectively under the same condition. Cyt c was reduced at high peptide concentration, whereas the reaction did not occur effectively at low concentration. The reaction rate varied with time owing to a decrease in the TyrTyrPhe concentration and the production of tyrosine derivatives during the reaction. The initial rate constants were 2.4 x 10(-4) and 8.1 x 10(-4) s(-1) at pH 7.0 and 8.0, respectively, for the reaction with 1.0 mM TyrTyrPhe in 10 mM phosphate buffer at 15 degrees C. The reciprocal initial rate constant (1/k(int)) increased linearly against the reciprocal peptide concentration and against the linear proton concentration, whereas logk(int) decreased linearly against the root of the ionic strength. These results show that deprotonated (TyrTyrPhe)(-), presumably deprotonated at a tyrosine site, reduces cyt c by formation of an electrostatic complex. No significant difference in the reaction rate was observed between the reaction under nitrogen and oxygen atmospheres. From the matrix-assisted laser desorption ionization time-of-flight mass spectra of the reaction products, formation of a quinone and other tyrosine derivatives of the peptide was supported. These products should have been produced from a tyrosyl radical. We interpret the results that a cyt c(ox)/(TyrTyrPhe)(-)right harpoon over left harpooncyt c(red)/(TyrTyrPhe)(*) equilibrium is formed, which is usually shifted to the left. This equilibrium may shift to the right by reaction of the produced tyrosyl radical with the tyrosine sites of unreacted TyrTyrPhe peptides.

The "pulvinar sign" in a case of paraneoplastic limbic encephalitis associated with non-Hodgkin's lymphoma

This paper reports a 59 year old woman with paraneoplastic limbic encephalitis associated with diffuse large B cell lymphoma. Her brain magnetic resonance imaging scan showed bilateral posterior thalamic hyperintensities, similar to the "pulvinar sign". Her symptoms included progressive psychiatric disturbance and resembled the initial symptoms of variant Creutzfeldt-Jakob disease (vCJD). Clinicians should consider this treatable disorder in the differential diagnosis of vCJD.

Comparison of a combination of midazolam and diazepam and midazolam alone as oral premedication on preanesthetic and emergence condition in children

BACKGROUND

Preanesthetic anxiety and emergence agitation are major challenges for anesthesiologists in pediatric anesthesia. Thus, midazolam has been used as premedication for children. However, midazolam alone is not effective for emergence agitation. The present study tested the effect of a combination of midazolam and diazepam on the preanesthetic condition and emergence behavior in children.

METHODS

Forty-two children were allocated to one of three groups: the NoPre group received no premedication; the Mi group received midazolam 0.5 mg kg(-1) orally; and the Mi + Di group received midazolam 0.25 mg kg(-1) and diazepam 0.25 mg kg(-1) orally. When anesthesia was induced with 7% sevoflurane in 100% oxygen, qualities of mask induction and sedation were rated. Anesthesia was maintained with sevoflurane (3-5%) in 100% oxygen. During emergence from anesthesia, the score of the child's emergence behavior was rated.

RESULTS

Children in the Mi and Mi + Di groups were more sedated than those in the NoPre group. A combination of midazolam and diazepam provided a better quality of mask induction, when compared with no premedication. Also, the children in the Mi + Di group were less agitated than those in the other groups during the emergence.

CONCLUSION

Children in the Mi + Di group were significantly more sedated at induction of anesthesia and less agitated during emergence from anesthesia.

Late resistance to imatinib therapy in a metastatic gastrointestinal stromal tumour is associated with a second KIT mutation

Currently, there are no data on the secondary resistance of gastrointestinal stromal tumours to imatinib. Here, we report a case of metastatic gastrointestinal stromal tumour that relapsed during imatinib therapy. Mutation analysis showed that the imatinib-resistant liver tumour contained two c-kit mutations.

Ectopically expressed PDX-1 in liver initiates endocrine and exocrine pancreas differentiation but causes dysmorphogenesis

To date, the potency of pancreatic and duodenal homeobox gene 1 (PDX-1) in inducing differentiation into insulin-producing cells has been demonstrated in some cells and tissues. In order to carry out efficient screening of somatic tissues and cells that can transdifferentiate into beta-cell-like cells in response to PDX-1, we generated CAG-CAT-PDX1 transgenic mice carrying a transgene cassette composed of the chicken beta-actin gene (CAG) promoter and a floxed stuffer DNA sequence (CAT) linked to PDX-1 cDNA. When the mice were crossed with Alb-Cre mice, which express the Cre recombinase driven by the rat albumin gene promoter, PDX-1 was expressed in more than 50% of hepatocytes and cholangiocytes. The PDX-1 (+) livers expressed a variety of endocrine hormone genes such as insulin, glucagon, somatostatin, and pancreatic polypeptide. In addition, they expressed exocrine genes such as elastase-1 and chymotrypsinogen 1B. However, the mice exhibited marked jaundice due to conjugated hyperbilirubinemia, and the liver tissue displayed abnormal lobe structures and multiple cystic lesions. Thus, the in vivo ectopic expression of PDX-1 in albumin-producing cells was able to initiate but not complete the differentiation of liver cells into pancreatic cells. The conditional PDX-1 transgenic mouse system developed in this study appeared to be useful for efficient screening of PDX-1 responsive somatic tissues and cells.

The shape parameter of liposomes and DNA-lipid complexes determined by viscometry utilizing small sample volumes

A minicapillary viscometer utilizing <0.5 ml of sample at a volume fraction of <0.1% is described. The calculated a/b of DPPC/DPPG multilamellar liposome was 1.14 as prolate ellipsoids and a/b of dioleoylpropyltrimethyl ammonium methylsulfate-DNA complex at a charge ratio of 4:1 (+/-) was 3.7 as prolate ellipsoids or 4.9 as oblate ellipsoids. The deviation of shape from perfect sphere is thus expressed quantitatively in more than two significant figures. In these measurement, the necessary amount of DNA is <0.5 mg.

Vasodilatory and electrophysiological actions of 8-iso-prostaglandin E2 in porcine coronary artery

We examined the effects of several E-ring and F-ring isoprostanes on mechanical and electrophysiological activity in porcine coronary artery. Several isoprostanes evoked concentration-dependent contractions, with 8-iso-PGE2 being the most potent (-log EC50 of 6.9 +/- 0.1); this excitatory effect has been described in detail elsewhere and was not examined further here. 8-iso-PGE2 evoked dose-dependent relaxations in tissues preconstricted with the thromboxane A2-agonist U46619 (10(-6) M), with a negative log EC50 of 6.0 +/- 0.1 (n = 5). 8-iso-PGE1 and 8-iso-PGF2 beta also evoked relaxations (albeit with lower potency), whereas the other F-ring isoprostanes (8-iso-PGF1 alpha, 8-iso-PGF1 beta, and 8-iso-PGF2 alpha) were largely ineffective in this respect. The potency and efficacy of 8-iso-PGE2 in reversing tone were not dependent upon the concentration of U46619 used to preconstrict the tissues (10(-8) to 10(-6) M), indicating a lack of U46619-induced functional antagonism of these responses. 8-iso-PGE2 was able to completely relax tissues that had been denuded of endothelium (as indicated by loss of responsiveness to bradykinin). 8-iso-PGE2-evoked relaxations were markedly reduced by elevating the K+ equilibrium potential using 30 mM KCl and abolished by 60 mM KCl; they were also sensitive to charybdotoxin (10(-7) M) but not to 4-aminopyridine (1 mM). 8-iso-PGE2 also caused membrane hyperpolarization and augmentation of outward K+ current. We conclude that 8-iso-prostaglandin E2 acts directly on the smooth muscle to increase K+ conductance, leading to membrane hyperpolarization and vasodilation.

Polyclonal nature of diffuse proliferation of interstitial cells of Cajal in patients with familial and multiple gastrointestinal stromal tumours

BACKGROUND

Diffuse proliferation of interstitial cells of Cajal (ICCs) in the myenteric plexus layer of the intestine has been described in patients with familial and multiple gastrointestinal stromal tumours (GISTs). However, it is not fully understood whether proliferation is polyclonal or monoclonal.

AIMS

To evaluate the clonal nature of diffuse ICC proliferation in familial and multiple GIST cases, we carried out clonal analysis using inactivation at the human androgen receptor (HUMARA) locus.

MATERIALS AND METHODS

Diffuse ICC proliferation tissues from three female patients were microdissected using a laser capture microdissection (LCM) system. Normal intestinal mucosal tissues were also microdissected for polyclonal controls and GIST tissues for monoclonal controls from the same patients, and genomic DNA was extracted. After digestion by restriction enzyme HhaI, the HUMARA locus was amplified by a fluorescent polymerase chain reaction (PCR) procedure and the PCR products were analysed.

RESULTS

One case was uninformative because it was homozygous at the HUMARA locus. In the two other cases, PCR products from the diffuse ICC proliferation showed two alleles as well as those from normal intestinal mucosal tissues, indicating that ICC proliferation was polyclonal. In contrast, PCR products from associated GIST tissues showed only one allele, indicating that GISTs were monoclonal.

CONCLUSION

The results suggested that diffuse ICC proliferation in familial and multiple GIST cases was non-neoplastic hyperplasia.

Weak interactions and molecular recognition in systems involving electron transfer proteins

Electrostatic interactions and other weak interactions between amino acid side chains on protein surfaces play important roles in molecular recognition, and the mechanism of their intermolecular interactions has gained much interest. We established that charged peptides are useful for investigating the molecular recognition character of proteins and their molecular interaction induced structural changes. Positively charged lysine peptides competitively inhibited electron transfer from reduced cytochrome f (cyt f or cytochrome c (cyt c) to oxidized plastocyanin (PC), due to neutralization of the negatively charged site of PC by formation of PC-lysine peptide complexes. Lysine peptides also inhibited electron transfer from cyt c to cytochrome c peroxidase. Likewise, negatively charged aspartic acid peptides interacted with the positively charged sites of cytfand cyt c, and competitively inhibited electron transfer from reduced cytfor cyt c to oxidized PC and from [Fe(CN)6]4- to oxidized cyt c. Changes in the geometry and a shift to a higher redox potential of the active site Cu of PC on oligolysine binding were detected by spectroscopic and electrochemical measurements, owing to the absence of absorption in the visible region for lysine peptides. Structural and redox potential changes were also observed for cyt f and cyt c by interaction with aspartic acid peptides.

Covered Gianturco stent for tracheal stricture: application of polychlorovinylidene and polyurethane as covering materials

The aim of this study was to assess the efficacy and safety of thin membranes of polychlorovinylidene (PCV) or polyurethane (PU) as covering materials for Gianturco stents in the treatment of severe tracheal stricture caused by intraluminal tumor. Manufactured Gianturco stents covered with PCV or PU membrane were used to treat six malignant and one benign tracheal stricture. The initial results, complications, clinical follow-up, bronchoscopic findings, and three autopsy microscopic examinations were reviewed. Informed consent was obtained after the nature of the treatment had been fully explained before every procedure. The stents successfully dilated the tracheal strictures, providing immediate relief of respiratory symptoms in all patients with no major complications. During the follow-up period, the covering materials prevented tumor ingrowth until death or intraluminal granuloma formation. Autopsies proved that no histological change occurs in the tracheal mucosa in response to the presence of PCV or PU; however, ulcer formation occurred in one patient and penetration of the stent struts into the tracheal wall in two. Bloody sputum with ulcer formation, minimal granuloma formation at the distal end of the stent, and abnormal bacterial load in the sputum were long-term complications. The Gianturco stent covered with PCV or PU membrane is a useful option as a palliative treatment for malignant and an emergent salvage for benign tracheal stricture, because both materials are thinner and less voluminous than the others. However, the indications for its use are limited to patients with poor prognoses, because hemoptysis, granuloma formation, and bacterial propagation remain problematic.

Spectroscopic observation of intermediates formed during the oxidative half-reaction of copper/topa quinone-containing phenylethylamine oxidase

The catalytic reaction of copper/topa quinone (TPQ) containing amine oxidase consists of the initial, well-characterized, reductive half-reaction and the following, less studied, oxidative half-reaction. We have analyzed the oxidative half-reaction catalyzed by phenylethylamine oxidase from Arthrobacter globiformis (AGAO) by rapid-scan stopped-flow measurements. Upon addition of dioxygen to the substrate-reduced AGAO at pH 8.2, the absorption bands derived from the semiquinone (TPQ(sq)) and aminoresorcinol forms of the TPQ cofactor disappeared within the dead time (<1 ms) of the measurements, indicating that the reaction of the substrate-reduced enzyme with dioxygen is very rapid. Concomitantly, an early intermediate exhibiting an absorption band at about 410 nm was formed, which then decayed with a rate constant of 390 +/- 50 s(-1). This intermediate was detected more prominently in the reaction in D2O buffer (pD 8.1) and was assigned to a Cu(II)-peroxy species. The assignment was based on the observation that addition of H2O2 to the substrate-reduced AGAO under anaerobic conditions led to the formation of a new band at about 415 nm, accompanied by partial quenching of absorption bands derived from TPQ(sq). Other intermediates exhibiting absorption bands at about 310 and 340 nm were also observed in the oxidative half-reaction. Kinetics of the disappearance of these latter bands did not correspond with that of the Cu(II)-peroxy band at 410 nm but did well with that of the increase of the 480 nm absorption band due to the reoxidized TPQ. Rapid increase of the absorption in the 320-370 nm region was also observed for the reaction of the substrate-reduced, Ni-substituted enzyme with dioxygen. On the basis of these results, a possible mechanism is proposed for the oxidative half-reaction of the bacterial copper amine oxidase.

Localized aggressive non-Hodgkin's lymphoma of the nasal cavity: a survey by the Japan Lymphoma Radiation Therapy Group

PURPOSE

To clarify the role of radiotherapy and chemotherapy in the treatment of patients with localized aggressive non-Hodgkin's lymphomas (NHL) originating in the nasal cavity.

METHODS AND MATERIALS

The survey, administered at 25 Japanese institutes in 1998, enabled us to collect the clinical data for 787 patients with localized aggressive NHL who were treated between 1988 and 1992.

RESULTS

There were 42 patients (5%) with nasal lymphomas. Twelve of these patients received radiotherapy alone, and 30 were treated with a combination of radiotherapy and chemotherapy. The median radiation dose was 47 Gy (22-66). Twelve patients were reviewed histopathologically according to REAL (Revised European-American Classification of Lymphoid neoplasms) classification. T-cell or natural killer (NK) cell lymphomas were detected in 9 patients (75%), and diffuse large B-cell lymphomas in 3 (25%). The 5-year overall and disease-free survival (DFS) rates of all patients were 57% and 59%, respectively. The 5-year DFS rate for the 30 patients treated with the combined therapy was 64% and that for the 12 patients treated with radiotherapy alone was 46% (p = 0.021). For the 34 patients with stage-modified International Prognostic Index (m-IPI) 0-1, the 5-year DFS rates of those treated with the combined therapy and radiotherapy alone were 68% and 45%, respectively (p = 0.020), but there was no difference in DFS rate among the two groups of patients with m-IPI 2-3. The 5-year local control rates of the patients who received >46 Gy (n = 22) and < or =46 Gy (n = 20) were 95% and 76% (p = 0.087), respectively. There was no significant difference among the 5-year DFS rates (62% vs. 67%) and local control rates (87% vs. 100%) of the patients with T-cell or NK-cell lymphoma and diffuse large B-cell lymphoma.

CONCLUSIONS

Patients with nasal lymphomas (m-IPI 0-1) should be treated with combined therapy. For the patients with high risk (m-IPI 2-3), the effectiveness of combined therapy was not clarified because of the small number of the patients. A high radiation dose >46 Gy may need to be used to achieve good local control.