Protective effect of histidine on iron (II)-induced hydroxyl radical generation in rat hearts

We investigated the efficacy of histidine on iron (II)-induced hydroxyl radical (.OH) generation in extracellular fluid of the rat myocardium using a flexibly mounted microdialysis technique (O system). Rats were anesthetized and a microdialysis probe was implanted in the left ventricular, followed by infusion of sodium salicylate in Ringer's solution (0.5 nmol/microL/min) to detect the generation .OH as reflected by the non-enzymatic formation of 2,3-dihydroxybenzoic acid (DHBA). Iron (II) clearly produced a concentration-dependent increase in .OH formation. A positive linear correlation between iron (II) and the formation of 2,3-DHBA (R2 = 0.987) was observed. However, histidine (25 mM) was infused through a microdialysis probe; iron (II) failed to increase the 2,3-DHBA formation obtained. To examine the effect of histidine on ischemia-reperfusion of the myocardium, the heart was subjected to myocardial ischemia for 15 min by occlusion of the left anterior descending coronary artery (LAD). When the heart was reperfused, a marked elevation of the levels of 2,3-DHBA was observed in the heart dialysate. When corresponding experiments were performed with histidine (25 mM)-pretreated animals, histidine prevented the ischemia-reperfusion induced .OH generation trapped as 2,3-DHBA. These results indicate that histidine protects the myocardium against ischemia-reperfusion damage by .OH generation.

Putidaredoxin-cytochrome p450cam interaction. Spin state of the heme iron modulates putidaredoxin structure

During the monooxygenase reaction catalyzed by cytochrome P450cam (P450cam), a ternary complex of P450cam, reduced putidaredoxin, and d-camphor is formed as an obligatory reaction intermediate. When ligands such as CO, NO, and O2 bind to the heme iron of P450cam in the intermediate complex, the EPR spectrum of reduced putidaredoxin with a characteristic signal at 346 millitesla at 77 K changed into a spectrum having a new signal at 348 millitesla. The experiment with O2 was carried out by employing a mutant P450cam with Asp251 --> Asn or Gly where the rate of electron transfer from putidaredoxin to oxyferrous P450cam is considerably reduced. Such a ligand-induced EPR spectral change of putidaredoxin was also shown in situ in Pseudomonas putida. Mutations introduced into the neighborhood of the iron-sulfur cluster of putidaredoxin revealed that a Ser44 --> Gly mutation mimicked the ligand-induced spectral change of putidaredoxin. Arg109 and Arg112, which are in the putative putidaredoxin binding site of P450cam, were essential for the spectral changes of putidaredoxin in the complex. These results indicate that a change in the P450cam active site that is the consequence of an altered spin state is transmitted to putidaredoxin within the ternary complex and produces a conformational change of the 2Fe-2S active center.

Early detection of radiation-induced liver injury in rat by superparamagnetic iron oxide-enhanced MR imaging

The detectability of early liver injury induced by irradiation was studied using magnetic resonance (MR) imaging enhanced with superparamagnetic iron oxide (SPIO), a tissue-specific contrast agent against the reticuloendothelial system (RES). In rat, 3 days after focal irradiation (0-10 Gy), MR imaging was performed and specimens were obtained to observe the phagocytic function of RES. The irradiated portion of the liver was visualized with a clear demarcation from the nonirradiated part by SPIO-enhanced MR images as a decrease in negative enhancement reflecting the function of RES (P < 0.05), whereas this was impossible with nonenhanced MR images. Significant regression was observed as a dose-related change of the signal intensity in the irradiated portion on SPIO-enhanced MR images (R = 0.867, P < 0.0001). SPIO-enhanced MR imaging was reliable for detecting the range and extent of liver injury a few days after low-dose irradiation, and it may be a useful procedure for verifying the target area in clinical cases of radiation therapy.

Analysis of the consensus binding sequence and the DNA-binding domain of ZF5

Murine ZF5 is a transcription factor with five zinc finger motifs that represses the c-myc gene by binding to two GC-rich elements at the promoter region. Because of its ubiquitous expression in a variety of tissues, elucidation of biological functions and cellular target genes of ZF5 is of great interest. As the first step of identifying cellular target genes, we have attempted to determine the consensus binding motif for ZF5. We succeeded in isolating 19 oligonucleotide duplex DNAs to which ZF5 binds and determined the binding sequences with DNase I footprinting analysis. From these sequences, we deduced the consensus binding motif for ZF5 to be GSGCGCGR. In addition, we have analyzed the DNA-binding domain of ZF5 by testing a series of deletion mutants. It turned out that the zinc fingers 3 and 4 of the five finger motifs play a critical role in DNA binding.

A new antidiabetic agent (JTT-501) rapidly stimulates glucose disposal rates by enhancing insulin signal transduction in skeletal muscle

A newly synthesized antidiabetic agent, JTT-501 is an isoxazolidinedione rather than a thiazolidinedione. An oral dose of JTT-501 (100 mg x kg(-1) x day(-1)) given to 12-week-old male Zucker fatty rats for 7 days led to the amelioration of both hyperinsulinaemia (40% of non-treated) and hypertriglyceridaemia (23% of non-treated) as well as a 2.4-fold increased insulin sensitivity as determined by a euglycaemic insulin clamp. In our study, we further evaluated the acute effect of JTT-501 on both the glucose infusion rates (GIR) and insulin signalling in skeletal muscle. Male Sprague-Dawley (SD) rats aged 10 weeks were injected intravenously with JTT-501 (5 mg/kg) and then a euglycaemic insulin clamp was initiated and glucose infusion rates monitored for 150 min. We found that this treatment increased the glucose infusion rate by 33% during the last 30 min in SD rats. After the clamp had been initiated for 30 min, the insulin-stimulated phosphatidylinositol 3-kinase (PI3-kinase) activities co-immunoprecipitated with insulin receptor substrate 1 (IRS-1) were also enhanced, resulting in increased glycogen synthase activities in the soleus muscles. Treatment with JTT-501 also enhanced the phosphorylation of insulin receptors and insulin receptor-substrate 1 rapidly as well as the phosphatidylinositol 3-kinase activities, which were stimulated by a bolus injection of insulin. Similarly, JTT-501 stimulated the glucose infusion rate by 30% and enhanced insulin signalling in Zucker fatty rats. In conclusion, a newly developed isoxazolidinedione, JTT-501, rapidly potentiates the insulin sensitivity of skeletal muscle by enhancing insulin signalling and could be useful for the treatment of insulin-resistant diabetic subjects.

Protective effect of histidine on MPP+-induced hydroxyl radical generation in rat striatum

We investigated the efficacy of histidine on MPP+-induced hydroxyl radical (.OH) formation in extracellular fluid of rat striatum. Rats were anesthetized and sodium salicylate in Ringer's solution (0.5 nmol microl-1 min-1) was infused through a microdialysis probe to detect the generation of.OH as reflected by the nonenzymatic formation of 2,3-dihydroxybenzoic acid (DHBA) in the striatum. MPP+ (5 mM) clearly produced an increase in.OH formation. However, histidine (25 mM) reduced the.OH formation by the action of MPP+. These results indicate that histidine protects MPP+-induced.OH formation in rat striatum.

Isolation of deoxycytidine kinase from Ehrlich carcinoma cells by affinity chromatography based on a substrate analog, 2'-C-cyano-2'-deoxy-1-beta-D-arabinofuranosyl-N4-palmitoylcytosine++ +

Deoxycytidine kinase from Ehrlich carcinoma cells was purified 10400-fold by ammonium sulfate fractionation and affinity chromatography using Sepharose 4B coupled to 2'-C-cyano-2'-deoxy-1-beta-D-arabinofuranosyl-N4-palmitoylcytosine , with a yield of 45%. The purified enzyme preparation showed a single major band with a molecular weight of 32000 on SDS-PAGE. The enzyme phosphorylated deoxyadenosine, deoxyguanosine, cytidine, and several deoxycytidine analogues as well as deoxycytidine. Also, the kinetic parameters of the enzyme for the substrates were estimated.

[A case of systemic lupus erythematosus overlapping with progressive systemic sclerosis accompanied by deposition of AA amyloid in the stomach]

A 52-year-old woman was admitted to our department because of fever and dysphasia in November 1994. She had noticed Raynaud's phenomenon, arthralgia, and stiffness in the skin for the past 20 years without receiving specific treatment. A diagnosis of progressive systemic sclerosis (PSS) was made based on the presence of sclerosis of the skin, sclerodactyly, pulmonary fibrosis, and the dilatation of the lower esophagus. It was also confirmed that systemic lupus erythematosus (SLE) overlapped based on the presence of an oral ulcer, polyarthralgia, leukocytopenia, renal dysfunction, positive tests for antinuclear antibodies and anti-DNA antibodies. A gastric biopsy specimen revealed amyloid deposits which showed green birefrigence by Congo red staining under polarized light microscopy. The disappearance of the green birefrigence after potassium permanganate treatment indicated that the deposits consisted of AA amyloid. No amyloid deposits were detected in the rectum or the kidney. The average of the SAA level in active SLE patients is 174 micrograms/ml in our department and the SAA level in the present case was 280 micrograms/ml. Although AA amyloidosis is rarely associated with SLE and PSS, a long-term elevation of SAA level could cause the development of amyloidosis even in the cases of SLE and PSS.

Glibenclamide, an antagonist of ATP sensitive K+ channels, blocks free radical generation in the rat myocardium

The present study examined the effect of glibenclamide, an ATP-sensitive K+ (K(ATP)) channels antagonist, on the potassium chloride (KCl)-induced hydroxyl free radical (.OH) generation. Sodium salicylate in Ringer's solution (0.5 nmol/microl per min) was infused directly through a microdialysis probe to detect the generation of .OH as reflected by the formation of dihydroxybenzoic acid (DHBA) in the myocardium of anesthetized rat. The high concentration of KCl (70 mM) significantly increased the level of 2,3- and 2,5-DHBA by the action of depolarization by KCl. However, in the presence of glibenclamide (10 microM), KCl failed to increase the 2,3- and 2,5-DHBA formation. Moreover, when allopurinol (10 mg/kg), a xanthine oxidase inhibitor, was administered by i.v. injection, the elevation of DHBA was not observed. These results suggest that openings of cardiac K(ATP) channel by depolarization evokes .OH generation via xanthine oxidase reaction.

NO and cGMP facilitate adenosine production in rat hearts via activation of ecto-5'-nucleotidase

We examined whether nitric oxide (NO), a possible cardioprotective substance, can increase the production of interstitial adenosine in the ventricular myocardium. A flexibly mounted microdialysis technique was used to measure the concentration of interstitial adenosine and to assess the activity of ecto-5'-nucleotidase in in vivo rat hearts. The microdialysis probe was implanted in the left ventricular myocardium of anesthetized rats and perfused with Tyrode solution containing adenosine 5'-monophosphate (AMP) at a rate of 1.0 microl min-1. The concentration of adenosine in the effluent (dialysate) was measured by high-performance liquid chromatography. Dialysate adenosine obtained during perfusion with the AMP-containing solution through the probe originated from the hydrolysis of AMP by endogenous ecto-5'-nucleotidase, and the level of adenosine reflected the activity of ecto-5'-nucleotidase in the tissue. S-Nitroso-N-acetylpenicillamine (SNAP, 0.3-3 mM), an NO donor, increased the dialysate adenosine measured in the presence of AMP (100 microM) in a concentration-dependent manner. However, in the presence of an NO-oxidizing agent, 2-(4-carboxyphenyl-4,4,5, 5-tetramethylimidazoline)-1-oxyl 3-oxide (carboxy-PTIO, 1 mM), the effect of SNAP was abolished. Another NO donor, (+/-)-(E)-4-ethyl-2-[(E)-hydroxyimino]-5-nitro-3-hexenamide (FK409, 1 mM) also increased adenosine production. 8-Bromo-cGMP (0.1-3 mM), a membrane-permeable cGMP analogue and a potent activator of cGMP-dependent protein kinase, increased the level of AMP-primed dialysate adenosine in a concentration-dependent manner. These results suggest that NO facilitates the production of interstitial adenosine in rat hearts in situ, via cGMP-mediated activation of ecto-5'-nucleotidase.

Dialysate pressure isobars in a hollow-fiber dialyzer determined from magnetic resonance imaging and numerical simulation of dialysate flow

A procedure to determine dialysate pressure isobars by comparing the results of magnetic resonance imaging (MRI) and numerical simulation of the dialysate flow was established. The assumption used in the filtration analyses, that the dialysate pressure varies only in the central-axial direction, is supported by the finding that the determined isobars have no steep radial gradient. MRI of the contrast solution permeating the hollow fibers verifies the uniformity of the hollow fiber density in the dialyzer.

Effects of lysophosphatidylcholine on the production of interstitial adenosine via protein kinase C-mediated activation of ecto-5'-nucleotidase

1. Adenosine plays a crucial role in the evolution of ischemic preconditioning. With the use of microdialysis techniques in in situ rat hearts, we assessed the activity of ecto-5'-nucleotidase (a key enzyme responsible for adenosine production), and examined the effects of lysophosphatidylcholine (LPC) on the production of interstitial adenosine. 2. The microdialysis probe was implanted in the left ventricular myocardium of anesthetized rat hearts and perfused with Tyrode solution containing adenosine 5'-monophosphate (AMP, 100 microM). With this system, the dialysate adenosine originates from the dephosphorylation of AMP, catalyzed by endogenous ecto-5'-nucleotidase. The level of dialysate adenosine is a measure of the ecto-5'-nucleotidase activity in vivo. 3. LPC at concentrations of 25 and 50 microM significantly increased the level of dialysate adenosine to 122.7+/-4.3% (n=4, P<0.05) and 158.6+/-7.2% (n=5, P<0.05) of the control, respectively. Chelerythrine (200 microM), a protein kinase C (PKC) inhibitor, completely abolished the increase of dialysate adenosine afforded by LPC (50 microM) (n=5). 4. These data provide the first evidence that LPC does increase the concentration of interstitial adenosine in rat hearts in situ, through the PKC-mediated activation of endogenous ecto-5'-nucleotidase.

Genomic cloning and characterization of the mouse POZ/zinc-finger protein ZF5

We isolated genomic DNA containing the entire sequence of ZF5, which was originally identified by its ability to repress the mouse c-myc promoter and which was characterized as one of the POZ (Poxvirus and zinc finger) proteins. The POZ motif is a protein-protein interaction interface found at the N-terminal region of zinc finger proteins. Sequence analysis demonstrated that the ATG translation initiation codon was separately located from the remainder of the coding sequence. Using both RNase protection and primer extension assay, a single major transcription start site was determined. Promoter analysis by transient transfection assay suggested positive autoregulation by ZF5 itself. The ZF5 N-terminal region, including the POZ domain, was required for this regulation. Sp1 also activated the ZF5 promoter and this activity was repressed by addition of ZF5. ZF5 expression was stronger in mouse ovary, lung and brain than in other organs.

High glucose-induced abnormal epidermal growth factor signaling

We have reported that high glucose conditions (27 mM for 4 days) induces activation of protein tyrosine phosphatases (PTPases) which are associated with impaired insulin signaling in Rat 1 fibroblasts expressing human insulin receptors [Maegawa, H. et al. (1995) J. Biol. Chem. 270, 7724-7730]. In this study, we found increased mRNA-levels of a non-receptor type PTPase, protein tyrosine phosphatase 1B (PTP1B), and receptor type PTPases, leukocyte common antigen-related phosphatase (LAR), and LAR-related phosphatase (LRP), under high glucose conditions. In accordance with these results, LAR content was significantly increased, whereas LRP content was not increased. Cytosolic PTP1B content was increased, but membrane-associated PTP1B content showed no detectable change. Pioglitazone, a thiazolidinedione, normalized increased cytosolic PTPase activity through reduction of cytosolic PTP1B content, but it had no effect on mRNA levels of these PTPases. Under the high glucose condition, we also found that epidermal growth factor (EGF)-stimulated signaling, including tyrosine-phosphorylation of EGF receptor and phosphatidylinositol 3'-kinase activities, was attenuated. Nevertheless, pioglitazone failed to restore the attenuated EGF-signaling. These results indicate that the high glucose conditions cause dysfunction of EGF receptor. However, the increased cytosolic PTP1B content is not involved in the abnormal regulation of EGF-signaling, in contrast to insulin-signaling.

High density culture of immortalized liver endothelial cells in the radial-flow bioreactor in the development of an artificial liver

Liver endothelial cells are important components of the tissue along the hepatic sinusoid. They are responsible for microcirculation in the liver and scavenger functions. It would therefore be important to include these cells in any hybrid type of artificial liver in addition to hepatocytes. However, it is difficult to culture these cells in vitro. The development of a liver endothelial cell line, which maintains the characteristics of the primary culture, would thus be of great benefit in the development of an artificial liver. In the present study we established immortalized liver endothelial cells from the liver of an H-2Kb-tsA58 transgenic mouse, which harbors the SV40 TAg gene. Hepatic sinusoidal cells isolated from H-2Kb-tsA58 mouse proliferated in the presence of gamma-interferon at 33 degrees C. Four clones were established, out of which clone M1 had the highest amounts of PGI2 production, as well as plasminogen activator activity and internalized acetylated low density lipoprotein. On culture dishes the M1 cells grew individually and spread. Sieve plates on the cell surface were not readily visible, but small pores were detected under electron microscopic observation. These results suggest that M1 clone cells originated from liver endothelial cells. Moreover it was possible to culture the immortalized liver endothelial cells in a radial-flow bioreactor for 5 days, with a maximum 6-keto prostaglandin F1alpha production of 25 microg per day. This suggests that immortalized liver endothelial cells and a radial-flow bioreactor can prove useful tools in the development an artificial liver.

Cytotoxic principles of a Bangladeshi crude drug, akond mul (roots of Calotropis gigantea L.)

Three cardenolide glycosides, calotropin (1), frugoside (2), and 4'-O-beta-D-glucopyranosylfrugoside (3), were obtained as the cytotoxic principles of "akond mul" (roots of Calotropis gigantea L.). The cytotoxicity of these compounds against various cell lines of human and mouse origin was tested. They showed similar cell line selectivity to those of cardiac glycosides such as digoxin and ouabain: they are toxic to cell lines of human origin, but not to those from mouse at 2 micrograms/ml.

Dynamic MRI of transcorneal dispersion of oxygen into the anterior chamber of human eye

To measure the transcorneal dispersion of oxygen into the anterior chamber, dynamic T1-weighted fast-spin-echo MRI (TR=2 seconds, TE=15 msec, 5-mm slice) of the human eye was performed both before and during oxygen supply to a full goggle placed on the face. During the course of the imaging, a significant increase in the signals in the anterior chamber occurred. This indicated that transcorneal dispersion of oxygen into the anterior chamber can be evaluated by this procedure, suggesting that this method may be useful for diagnosing dysfunction of the cornea or aqueous flow.

GC/MS analysis of urinary excretion of 9alpha,11beta-PGF2 in acute and exercise-induced asthma in children

BACKGROUND

9Alpha,11beta-prostaglandin (PG) F2 is an initial metabolite of PGD2 which has a potent bronchoconstrictive activity.

OBJECTIVES

We measured the urinary levels of 9alpha,11beta-PGF2 in asthmatic children to investigate its role in not only acute asthmatic attack in a time course study but also in exercise-induced asthma (EIA).

METHODS

In the acute asthma study, 30 asthmatic children were examined. Urine samples were collected on the first, third, and sixth days. Urinary levels of 9alpha,11beta-PGF2 were measured with gas chromatography mass spectrometry using the electron impact method. In the exercise challenge study, 14 children with EIA and 14 children without EIA were studied. Urine samples were collected before exercise challenge, and at 1 h, and 5 h after exercise challenge. Urinary levels of 9alpha,11beta-PGF2 were measured.

RESULTS

Elevated urinary levels of 9alpha,11beta-PGF2, which were observed on the first day when treatment was started in the hospital, were gradually decreased on the third day (P < 0.05), and on the sixth day (P < 0.01). A significant correlation between urinary levels of 9alpha,11beta-PGF2 and symptom scores (P < 0.005) was observed on the first day. In EIA, there was a significant increase in urinary levels of 9alpha,11beta-PGF2 at 1 h (P < 0.01) and at 5 h (P < 0.01) after exercise challenge, but not in the children without EIA.

CONCLUSION

9Alpha,11beta-PGF2 may be involved in the pathogenesis of acute and exercise-induced asthma in children.

Effect of .OH scavenging action by non-SH-containing angiotensin converting enzyme inhibitor imidaprilat using microdialysis

We examined the effect of non-SH-containing angiotensin converting enzyme (ACE) inhibitor imidaprilat on hydroxyl radical (.OH) generation using microdialysis. Salicylic acid in Ringer's solution containing sodium salicylate (0.5 n mol microL-1 min-1) was infused directly through a microdialysis probe to detect the generation of .OH as reflected by the formation of 2,3-dihydroxybenzoic acid (DHBA) in the myocardium of anesthetized rats. We compared the ability of two non-SH-containing ACE inhibitors (imidaprilat and enalaprilat) with an -SH-containing ACE inhibitor (captopril) to scavenge the .OH. When iron (II) was administered to animals pretreated with these three ACE inhibitors, a decrease in 2,3-DHBA of all three compounds was observed, as compared with the iron (II) only-treated group. All three ACE inhibitors were able to scavenge .OH generated by the action of iron (II). However, imidaprilat is a free radical scavenger more potent than enalaprilat. These results suggested that ACE inhibitors are probably not only related to the presence of the SH radical.

Lung as reservoir for antidepressants in pharmacokinetic drug interactions

BACKGROUND

Although high-affinity imipramine binding sites have been reported in both rat and human lung, the role of the lungs in the pharmacokinetics of antidepressants has not received much attention. Substantial accumulation of selective serotonin-reuptake inhibitors (SSRIs) in the lungs has been reported. We have investigated the role of the lungs in pharmacokinetic drug interactions between tricyclic antidepressants and SSRIs.

METHODS

We used a carbon-11-labelled form of the imipramine derivative cyanoimipramine to measure uptake in the lungs and brain of healthy volunteers by positron emission tomography. Clomipramine (50 mg) was administered to measure the effect of antidepressants with high affinity for the serotonin transporter on lung and brain uptake.

FINDINGS

A large proportion of the injected 11C-cyanoimipramine (68-86% in the four volunteers) was extracted by the lungs. Clomipramine decreased the lung uptake from 68% to 35% and from 81% to 54% in the two volunteers studied. By contrast, whole-brain uptake was low in control studies (1.7-2.0% in three volunteers) and increased after clomipramine administration (to 4.5-4.9%). Plasma radioactivity was also higher after clomipramine than in control studies.

INTERPRETATION

The lungs may function as a reservoir for antidepressants with high affinity to the serotonin transporter. The accumulated antidepressants may be displaced by other antidepressants, and this displacement would substantially increase plasma concentrations and thus cause toxic effects.

Development and biochemical characterization of a 2'-C-cyano-2'-deoxy-1-beta-D-arabino-pentofuranosylcytosine (CNDAC)-resistant variant of the human fibrosarcoma cell line HT-1080

2'-C-Cyano-2'-deoxy-1-beta-D-arabino-pentofuranosylcytosine (CNDAC) is an antitumor nucleoside with a novel chemical structure that exerts potent antitumor activity against various human tumor cells in vitro and in vivo. In order to be active it needs to be phosphorylated by deoxycytidine (dCyd) kinase. We induced resistance to CNDAC in the human fibrosarcoma cell line HT-1080 by exposure to increasing concentrations of CNDAC. The resistant cells showed over 560 times higher resistance as compared to that of the parental HT-1080 cells and were cross-resistant to the other 2'-deoxycytidine derivatives. The dCyd kinase mRNA expression of the resistant cells decreased and there was the expression of aberrant mRNA of dCyd kinase which contained a 116-nucleotide deletion within the coding region, corresponding to the fifth exon of the gene. The dCyd kinase enzymatic activity of the resistant cells was deficient. The initial uptake of CNDAC into the resistant cells was similar to that of the parental cells. However, the incorporation of CNDAC into the DNA fraction of the resistant cells was significantly less than that of the parent cells. These results led us to conclude that the acquired resistance to CNDAC can be attributed to a deficiency of dCyd kinase activity, which should be based on a remarkable decrease in mRNA expression and genetic mutation of the dCyd kinase gene, but not on cellular CNDAC accumulation.

Simultaneous quantitative analysis of prostaglandins and thromboxane after low-dose X irradiation

The appearance of prostaglandins and thromboxane in mouse serum after X irradiation was observed by simultaneous quantitative analysis using gas chromatography/mass spectrometry/selected ion monitoring with stable isotope dilution methods. Mice of two strains (C57BL/CN Jcl and BALB/c) showed similar responses to X irradiation. In C57BL/6N Jcl mice, 0.2 Gy irradiation elicited a significant increase in generation of prostanoids: Immediately after irradiation, the 6-keto PGF1 alpha:TXB2 ratio and the level of PGE2 increased, after 20 min 6-keto PGF1 alpha and PGE2 increased, and after 4 h PGE1 and PGE2 increased. In BALB/c mice, generation of prostanoids was increased significantly immediately after irradiation (6-keto PGF1 alpha, 6-keto PGF1 alpha:TXB2 ratio, PGE2), and the increase was maintained from 20 min to 4 h (PGE1, PGE2) after 0.2 Gy irradiation. In C57BL/6N Jcl mice, a significant increase in production of 9alpha,11beta-PGF2 was observed at 20 min after irradiation. In BALB/c mice, a significant increase in 9alpha,11beta-PGF2 was seen immediately after irradiation and was maintained for 20 min. In C57BL/6N Jcl mice, the level of 8-epi PGF2 alpha was clearly increased 4 h after 4 Gy irradiation. A slight and slow increase was also seen after 0.2 Gy irradiation. In BALB/c mice, 8-epi PGF2 alpha was increased significantly at 20 min and 4 h after 4 Gy irradiation. These results show that 0.2 Gy irradiation stimulates production of prostanoids related to the inflammatory response in mice.

Adenosine deaminase activity in rat intestine: assay with a microdialysis technique

Using microdialysis, we measured adenosine deaminase activity in rat intestine by detecting inosine, a breakdown product of adenosine. The dialysis probe consisted of a 3 x 0.22 mm dialysis fiber with a 50,000 mol wt cut off. When the probe was perfused at 1 microl/min in vitro, the average relative recovery rate of inosine was 22.1+/-0.9%). The dialysis probe was implanted in the intestinal mucosa and perfused with Tyrode solution containing adenosine at 1 microl/min. The dialysate samples were analyzed for inosine by high-performance liquid chromatography with ultraviolet (HPLC-UV) detection at 260 nm. When adenosine (100-1000 microM) was perfused, the level of inosine increased dose-dependently and was saturatable at about 1 mM adenosine. The ED50 of adenosine was 192.6 microM, with a maximum attainable inosine concentration of 59.7 microM. In the presence of aminoguanidine, a adenosine deaminase inhibitor (10 mM or 10 n mol/microl/min), the elevation of inosine was not observed. The dialysis technique makes it possible to measure adenosine deaminase activity in intestinal mucosa.

Pyruvate improves deleterious effects of high glucose on activation of pentose phosphate pathway and glutathione redox cycle in endothelial cells

In our previous study (Diabetes 44:520-526, 1995), endothelial cells cultured in high glucose condition showed impairment of an oxidant-induced activation of the pentose phosphate pathway (PPP) and a reduced supply of NADPH to the glutathione redox cycle. To gain insight into the mechanisms of this impairment, the protective effect of pyruvate was studied in human umbilical vein endothelial cells cultured in either 5.5 mmol/l glucose (normal glucose [NG] condition) or 33 mmol/l glucose (high glucose [HG] condition). Through pretreatment of cells with 0.2 mmol/l pyruvate for 5-7 days in the HG condition, glucose oxidation through the PPP and total cellular NADPH content in the presence of 0.2 mmol/l H2O2 were increased by 54 (P < 0.05) and 34%, respectively, and glutathione-dependent degradation of H2O2 in HG cells was enhanced by 41% (P < 0.01), when compared with those cells to which pyruvate was not added. The addition of pyruvate significantly reduced the fructose 1,6-bisphosphate (FDP) content and free cytoplasmic NADH/NAD ratio, estimated by increased pyruvate/lactate ratio in NG and HG cells exposed to H2O2. Furthermore, the addition of pyruvate also showed a 46% reduction (P < 0.01) of endothelial cell damage induced by H2O2 in HG cells. These results indicate that abnormalities in PPP activation and glutathione redox cycle activity induced by H2O2 in HG cells are compensated, and that the accentuated reductive stress is improved by an addition of pyruvate. These pyruvate effects are associated with protection against an oxidant-induced endothelial cell injury in the high glucose condition.

Human hepatic carbohydrate metabolism. Dynamic observation using 13C MRS without proton decoupling

PURPOSE

Dynamic natural-abundance 13C MR spectroscopy (MRS) studies without proton decoupling were performed in the human liver using commercial 1.5 T MR equipment.

MATERIAL AND METHODS

A single tuned custom-made circular surface coil with an OD of 20 cm operating at 16.04 MHz was used for the 13C study. Seventy-five grams of glucose dissolved in water was administered for the natural-abundance 13C-MRS dynamic study which lasted for approximately 40 to 60 min. Data acquisition was broken into 20-min and 1.7-min blocks. Localized proton shimming with a whole-body coil was performed with sufficient volume to include the observing area of the surface coil; the line width of the water signal was less than 20 Hz.

RESULTS AND CONCLUSION

The glucose and glycogen spectra were clearly visible at 80 to 120 ppm after oral administration of the glucose solution. These data demonstrate that dynamic hepatic carbohydrate metabolism can be observed with commercially available MR equipment. Given that the human hepatic glycogen pool reaches maximum level within less than 10 min, this technique should provide a direct diagnosis of hepatic carbohydrate metabolic disorders.

The measurement of blood flow parameters with deuterium stable isotope MR imaging

METHODS

Because there are no radioactive hydrogen isotopes which can be used for clinical examinations, deuterium as a non-radioactive, freely diffusible tracer has some advantages compared with the radioactive tracers in the measurement of blood flow parameters. A non-invasive technique to estimate the mean tissue blood flow parameter in vivo was developed by using deuterium nuclear magnetic resonance (NMR) imaging in rat. We obtained the NMR signal changes from deuterium NMR images in nine male Wister rats after intravenous injection of D2O and applied exponential curve fitting analyses to calculate blood flow parameters of the brain, heart and skeletal muscle.

RESULTS

While fitting the reducing of the monoexponential function yielded a blood flow parameter of 27.9 +/- 1.6 ml/min/100 g tissue weight for the brain and 46.7 +/- 3.7 ml/min/100 g tissue weight for the heart, fitting the early reducing of the signal intensity of the biexponential function yielded a blood flow parameter of 95.6 +/- 10.9 ml/min/100 g tissue weight for the brain and 108.0 +/- 13.1 ml/min/100 g tissue weight for the heart. The mean muscle blood flow parameter determined by the monoexponential uptake function was 43.8 +/- 7.3 ml/min/100 g tissue weight.

CONCLUSIONS

The blood flow parameter measurement by means of an imaging coil for deuterium is less invasive and reflects the mean tissue blood flow parameter for the entire tissue sample more homogeneously than spectroscopic monitoring.

The effect of glibenclamide on the production of interstitial adenosine by inhibiting ecto-5'-nucleotidase in rat hearts

1. Adenosine exerts cardioprotective effects on the ischaemic myocardium. The production of adenosine in the ischaemic myocardium is attributed primarily to the enzymatic dephosphorylation of adenosine 5'-monophosphate (AMP) by 5'-nucleotidase. We determined the activity of 5'-nucleotidase in rat hearts. The objective of the study was to determine the effects of ATP-sensitive K+ (K[ATP]) channel antagonists (glibenclamide and 5-hydroxydecanoate) on the production of adenosine, by use of a flexibly mounted microdialysis technique. 2. Rats were anaesthetized and the microdialysis probe was implanted in the left ventricular myocardium, followed by perfusion with Tyrode solution. The baseline level of dialysate adenosine was 0.51 +/- 0.09 microM (n = 16). Introduction of AMP (100 microM) through the probe increased the dialysate adenosine markedly to 9.79 +/- 0.43 microM (n = 12, P < 0.001 vs baseline), and this increase was inhibited by the ecto-5'-nucleotidase inhibitor, alpha,beta-methyleneadenosine 5'-diphosphate (100 microM), to 0.76 +/- 0.12 microM (n = 8). Thus, the dialysate adenosine noted during the perfusion of AMP originated from dephosphorylation of AMP by ecto-5'-nucleotidase, and the dialysate level of adenosine attained reflects the ecto-5'-nucleotidase activity in the tissue in situ. 3. Glibenclamide (0.1-100 microM) decreased the adenosine concentration measured during the perfusion of AMP (100 microM) in a concentration-dependent manner (IC50 = 10.5 microM). In contrast, 5-hydroxydecanoate (10-100 microM) did not affect the concentrations of dialysate adenosine, measured in the presence of AMP (100 microM). These results suggest that glibenclamide inhibits the activity of endogenous ecto-5'-nucleotidase and decreases the concentration of adenosine in the interstitial space of rat ventricular muscles in situ.

Early detection of peritoneal dissemination of gastrointestinal cancers by reverse-transcriptase polymerase chain reaction

We examined the usefulness of the reverse-transcriptase polymerase chain reaction (RT-PCR) analysis for E-cadherin mRNA in the early diagnosis of peritoneal dissemination of gastric and colorectal cancers. The RT-PCR analysis was performed on RNA samples extracted from cells which were collected preoperatively from ascites or intraperitoneally infused fluid. E-cadherin mRNA was detected in 2/2 cases (100%) graded into P-1 peritoneal dissemination, indicating the presence of metastatic cells. In the cases with P-2 and P-3 dissemination the gene expression was detected in 2/3 (67%) and 3/5 (60%), respectively. The RT-PCR analysis was more sensitive for P-1 dissemination than cytological examination. These results suggest that determination of E-cadherin gene expression is useful for the early detection of peritoneal dissemination in gastrointestinal cancer because of its high sensitivity and specificity.

Stimulation of alpha 1-adrenoceptors and protein kinase C-mediated activation of ecto-5'-nucleotidase in rat hearts in vivo

1. To determine whether protein kinase C (PKC)-mediated activation of ecto-5'-nucleotidase would increase interstitial adenosine concentrations in the rat heart in vivo, we made use of the microdialysis technique and a flexibly mounted probe, which was implanted in the left ventricular myocardium and perfused with Tyrode solution. 2. The baseline level of dialysate adenosine was 0.51 +/- 0.09 microM (n = 16). Perfusion of adenosine 5'-monophosphate (AMP, 100 microM) through the probe increased the dialysate adenosine concentration markedly to 9.25 +/- 0.46 microM (n = 15). alpha, beta-Methyleneadenosine 5'-diphosphate (AOPCP, 100 microM), an inhibitor of ecto-5'-nucleotidase, abolished the AMP-induced increase in dialysate adenosine, but did not affect the baseline level of adenosine. These observations suggest that the dialysate adenosine obtained during the perfusion with AMP, but not the baseline levels of adenosine, originated from the dephosphorylation of AMP by ecto-5'-nucleotidase. Thus, the level of adenosine measured during AMP perfusion gives an index of the activity of ecto-5'-nucleotidase in the tissue. 3. Noradrenaline (10 microM) increased the adenosine concentration measured in the presence of 100 microM AMP (i.e. the activity of ecto-5'-nucleotidase) by 38.7 +/- 9.6% (n = 5, P < 0.05), an increase which was inhibited by an antagonist of the alpha 1-adrenoceptor (prazosin, 50 microM) or of PKC (chelerythrine, 10 microM). Further application of either the alpha 1-adrenoceptor agonist methoxamine (100 microM) or the diacylglycerol analogue 1,2-dioctanoyl-sn-glycerol (DOG, 100 microM) also increased the adenosine concentration by 35.1 +/- 10.0% (n = 6, P < 0.05) or 40.6 +/- 8.3% (n = 5, P < 0.05), respectively. 4. The presence of okadaic acid (50 microM), an inhibitor of protein phosphatase, enhanced the noradrenaline-induced increase in adenosine concentration by 112.4 +/- 35.9% (n = 4, P < 0.05), to a level significantly (P < 0.05) greater than the increase caused by noradrenaline alone (38.7 +/- 9.6%). 5. These data provide the first evidence that alpha 1-adrenoceptor stimulation and the subsequent activation of PKC can increase adenosine concentrations in interstitial spaces of ventricular muscle in vivo, through activation of endogenous ecto-5'-nucleotidase.

Evidence of hydroxyl free radical generation by calcium overload in rat myocardium

Although calcium (Ca2+) is important in cardiac dysfunction and has also been reported as a source of oxidative toxicity, the connection between Ca2+ overload and oxygen free radicals in the myocardium is not clear. We have investigated whether Ca2+ overload generates hydroxyl free radicals in rat ventricle. HPLC with electrochemical detection was used to measure the levels of 2,3- and 2,5-dihydroxybenzoic acid (DHBA) formed when the hydroxyl free radical reacts with salicylate. Ringer's solution containing salicylic acid (0.5 nmol microL-1 min-1) was infused through a microdialysis probe in the region of the left anterior descending coronary artery of the rat ventricle. A positive linear correlation was obtained between Ca2+ and hydroxyl free radical formation trapped as 2,3-DHBA (r2 = 0.976) and 2,5-DHBA (r2 = 0.982) in the myocardial dialysate. The administration of ouabain (1 mg kg-1, i.v.), a Ca2+ elevator, into the femoral vein significantly increased the level of 2,3- and 2,5-DHBA. These results indicate that Ca2+ overload generates hydroxyl free radicals in rat heart.

[Measurement of cerebral blood flow using phase-contrast MRI]

The development of phase-contrast magnetic resonance imaging(P-C MRI) provides a noninvasive method for measurement of volumetric blood flow(VFR). The VFR of the left and right internal carotid arteries and basilar artery were measured using P-C MRI, and total cerebral blood flow(tCBF) was calculated by summing up the VFR values in three vessels. We investigated the changes in these blood flows as influenced from age, head size, height, weight, body surface area and handedness. Moreover, regional CBF(rCBF) was measured by combining with the single photon emission computed tomography(SPECT) of 123I. The blood flows were 142 +/- 58 mL/ min(mean +/- SD) in the basilar artery, 229 +/- 86 mL/min in the left, 223 +/- 58 mL/min in the right internal carotid artery, and tCBF was 617 +/- 128 mL/min(Ref. Magn Resn Imaging 14:P. 1143, 1996). Significant increases were observed in head-size-related change of VFR in the basilar artery and height-related change of tCBF. The value of rCBF was easily acquired in combination with SPECT. Phase-contrast MRI is useful for a noninvasive and rapid analysis of cerebral VFR and has potential for clinical use.

Use of microdialysis for in-vivo monitoring of hydroxyl free-radical generation in the rat

Free-radicals are reported to cause the tissue-damage associated with some toxins and diseases, yet there is no suitable method for routine in-vivo monitoring of these species. This paper introduces an in-vivo microdialysis technique in which the hydroxyl radical reacts with salicylate to generate dihydroxybenzoic acids (DHBA) which are measured by HPLC with electrochemical detection. When pargyline, a monoamine oxidase inhibitor, was infused into rat brain, the levels of DHBA increased markedly. When noradrenaline was administered to animals pre-treated with pargyline, DHBA levels increased markedly compared with the group treated with noradrenaline only. When the heart was subjected to 15-min regional ischaemia by occlusion of the left anterior descending coronary artery, levels of DHBA in heart dialysate were unchanged. Electrical stimulation of the stellate ganglion resulted in marked elevation of levels of DHBA the myocardial dialysate. Infusion of Fe2+ into rat liver resulted in increased formation of DHBA. When the intestine was rendered ischaemic for 10, 20 and 30 min, the highest DHBA level was obtained after 10-min ischaemia and the lowest after 30 min. These results confirm that free-radical production might make a major contribution at certain stages in the progression of the injury.

[Metabolic imaging of human brain tumors: H-1 chemical shift imaging and PET]

Positron Emission Tomography(PET) and Proton Chemical Shift Imaging(1H-CSI) has provided a cerebral metabolism. The glucose analog fluorine-18 fluorodeoxy-glucose(FDG) and amino acid analog 11C-L-methionine is the most commonly used PET tumor tracer. This time we compare with 1H-CSI and PET in gliomas and metastatic brain tumor with computer-assisted fusion images. We experienced some cases of the brain tumor. One case is metastatic brain tumor after radiation therapy, localized in right parietal hemisphere, with hemorrhage, and slightly accumulated Gd-DTPA in tumors. 11C-methionine PET demonstrates defects in tumors, but slight accumulated surrounding tumors. Accumulation of PET lesion is not elevated choline in CSI, but lactate is accumulated in tumors. Choline signal elevation seen in brain neoprasms, associated with increased cellular proliferation. Accumulation of PET and another accumulation of lactate in tumor are not demonstrate recurrence. Fusion image of PET and CSI is useful in understanding metabolism of brain tumor.

Anti-tumor mechanisms of 3'-ethynyluridine and 3'-ethynylcytidine as RNA synthesis inhibitors: development and characterization of 3'-ethynyluridine-resistant cells

To discover the mechanisms of anti-tumor action of 3'-ethynyluridine (EUrd) and 3'-ethynylcytidine (ECyd), we established an EUrd-resistant variant from human fibrosarcoma HT-1080 cells. The cells were cross-resistant to ECyd. Uridine/cytidine kinase activity diminished in the resistant cells. The incorporation of EUrd and ECyd into the RNA fraction in the resistant cells was less than that of the parental cells. EUrd-triphosphate inhibited RNA synthesis by human RNA polymerase II. The results led us to conclude that EUrd and ECyd are phosphorylated by uridine/cytidine kinase to 5'-triphosphates, and that their triphosphates might inhibit RNA polymerase.

Protective effect of diltiazem on myocardial ischemic injury associated with .OH generation

We examined the protective effect of diltiazem, a calcium antagonist, on myocardial ischemic injury associated with generation of hydroxyl free radicals (.OH). Salicylic acid in Ringer's solution (0.5 nmol.microliter-1.min-1) was infused directly through a microdialysis probe to detect the generation of .OH as reflected by the formation of 2,3-dihydroxybenzoic acid (DHBA) in the myocardium. Cardiac dialysate was assayed for 2,3-DHBA by a high-performance liquid chromatographic-electrochemical (HPLC-EC) procedure. The heart was subjected to myocardial ischemia for 15 min by occlusion of left anterior descending artery (LAD). The presence of .OH was indicated in the ischemic reperfused rat heart. However, when heart was reperfused, the elevation of 2,3-DHBA by 15-min ischemia was not observed in the ischemic zone following systemic administration of diltiazem (100 micrograms.min-1.kg-1), a calcium antagonist. When corresponding experiments were performed with allopurinol (10 mg.kg-1) administration of i.v. injection, the elevation of 2,3-DHBA was not observed. These results suggest that diltiazem may suppress the .OH generation from xanthine-xanthine oxidase system by ischemia-reperfusion.

Cardiac microdialysis of salicylic acid .OH generation on nonenzymatic oxidation by norepinephrine in rat heart

The effect of pargyline, a monoamine oxidase inhibitor, on the generation of hydroxyl free radicals (.OH) was investigated using cardiac microdialysis. Salicylic acid in Ringer's solution (0.5 nmol x microL(-1) x min(-1)) was infused directly through a microdialysis probe to detect the generation of .OH as reflected by the formation of dihydroxybenzoic acid (DHBA) in the myocardium of anesthetized rats. When pargyline (100 nmol x microL(-1) x min(-1)) was infused in rat heart, the level of norepinephrine (NE) gradually increased in a time-dependent manner and an increase of DHBA was also observed. When NE was administered to the pargyline pretreated animals, a marked elevation in the levels of 2,3- and 2,5-DHBA formation was obtained, as compared to the group treated with NE only, showing a positive linear correlation between NE and .OH formation trapped as 2,3-DHBA (R2 = 0.981) or 2,5-DHBA (R2 = 0.984) in the dialysate. NE clearly produced an increase in .OH formation. These results indicate that accumulation of NE in the extracellular fluid elicited by pargyline can be auto-oxidized, which in turn, leads (possibly by an indirect mechanism) to the formation of cytotoxic .OH free radicals.

Continuous isoproterenol inhalation therapy in children with severe asthmatic attack

We studied the 1-type isoproterenol inhalation therapy for patients with severe asthmatic attacks who were admitted at the Department of Allergy of National Children's Hospital from 1981 to 1991. One hour after l-type isoproterenol inhalation therapy, statistically significant effects were noted with regard to the asthmatic status. Moreover, no side effect was found amoung the subjects. From these data, 1-type isoproterenol inhalation therapy is thought to be effective for severe asthmatic attacks.

[Immunohistochemical study of thymidine phosphorylase in uterine cervical intraepithelial neoplasia]

Studies have shown that thymidine phosphorylase (TdRPase) activity in various tumors is higher than that in normal tissues. We studied the immunohistochemical localization of TdRPase in uterine cervical intraepithelial neoplasia (CIN) using monoclonal antibody against TdRPase. Sixty-nine patients were studied: CIN 1, 14; CIN 2, 15; CIN 3 (severe dysplasia), 23; CIN 3 (carcinoma in situ), 17. Immunoreactivity for TdRPase was found in 29% of CIN 1, 40% of CIN 2, 70% of CIN 3 (severe dysplasia), and 88% of CIN 3 (carcinoma in situ), showing increasing incidence with the progression of tumor grade. Furthermore, in higher grade tumor, more immunoreactive cells were found with increased intensity of immunoreaction. Both nucleus and cytoplasm of atypical cells showed immunoreactivity in most TdRPase positive cases, while either nucleus or cytoplasm was positive in a few cases. The stromal tissues were negative for the antibody except 3 cases of CIN 3 (carcinoma in situ) in which the stromal tissues adjacent to the tumor was positive. Our data suggest that immunoreactivity of TdRPase in CIN may correlate with the grade of CIN.

Acacia concinna saponins. I. Structures of prosapogenols, concinnosides A-F, isolated from the alkaline hydrolysate of the highly polar saponin fraction

A highly polar saponin mixture from pods of Acacia concinna (Leguminosae) was hydrolyzed with alkali to yield five new triterpenoidal prosapogenols named concinnosides A (6), B (3), C (7), D (4), and E (8), together with four known glycosides, acaciaside, (2), julibroside A1 (10) julibroside A3 (9), albiziasaponin C (5), and their aglycone, acacic acid lactone (1). The structures of these new prosapogenols were elucidated based on spectroscopic means. A less polar saponin fraction from the pods gave spinasteryl glucoside and its dihydro derivative.

Protective effect of carbidopa on hydroxyl radical generation in the rat striatum by dopamine

The effect of L-3,4-dihydroxyphenylalanine (L-DOPA) on the generation of hydroxyl free radicals (.OH) was investigated using striatal microdialysis technique. Salicylic acid in Ringer's solution (0.5 nmol.microliters-1.min-1) was infused directly through a microdialysis probe to detect the generation of .OH as reflected by the formation of dihydroxybenzoic acids (DHBA) in the striatum. When L-DOPA (0.1 mM; 1 microliter.min-1) was infused in the rat brain, the level of 3,4-dihydroxyphenylacetic acid (DOPAC) gradually increased in a time-dependent manner. In addition, a marked elevation of DHBA was observed. However, in the presence of carbidopa, a decarboxylase inhibitor, the elevation in DHBA formation was not observed. These results suggest that carbidopa may suppress the .OH generation by dopamine (DA).

Insulin signaling and its regulation of system A amino acid uptake in cultured rat vascular smooth muscle cells

Hyperinsulinemia has been recognized as an independent risk factor for atherosclerosis. However, its exact mechanisms are still unclear. In our previous work, we showed that 10 nmol/L insulin stimulated neither mitogen-activated protein kinase (MAP kinase) activity nor [3H]thymidine incorporation but did stimulated S6 kinase through the specific insulin receptors in cultured rat vascular smooth muscle cells (VSMCs). In this study, we observed that > or = 1 nmol/L insulin stimulated tyrosine phosphorylation of insulin receptor substrate-1 (IRS-1) and activated IRS-1-dependent phosphatidylinositol 3'-kinase (PI 3'-kinase) and p70 S6 kinase (p70S6K) but not MAP kinase (extracellular signal-regulated kinase 2) and p90 S6 kinase (p90RSK). However, 10 nmol/L insulin-like growth factor I stimulated all these pathways. Finally, 10 nmol/L insulin stimulated alpha-amino-isobutyric acid (AIB) uptake, and wortmannin (100 nmol/L) completely inhibited insulin-stimulated AIB uptake, whereas rapamycin (20 nmol/L) had no such effect. Furthermore, cycloheximide (10 micrograms/mL) completely inhibited insulin-stimulated AIB uptake, but actinomycin D (5 micrograms/mL) failed to inhibit this. Thus, we reached the following conclusions: (1) Insulin (1 nmol/L) induced phosphorylation of IRS-1 and activated the PI 3'-kinase and p70S6K pathways in VSMCs, even though 10 nmol/L insulin did not significantly stimulate MAP kinase or p90RSK. (2) Stimulation of AIB uptake by insulin was regulated at the translational level via wortmannin-sensitive pathways but not p70S6K pathways.

SHPTP2 serves adapter protein linking between Janus kinase 2 and insulin receptor substrates

To investigate the role of Janus kinase family (JAK1 and JAK2) in insulin signaling, we assessed their insulin-induced associations with other molecules in the cells overexpressing insulin receptors (HIRc and CHO-IR). After insulin stimulation, pp185 proteins (insulin receptor substrate, IRS) were co-immunoprecipitated with both kinases by alpha JAK1 and alpha JAK2 antibodies. However, JAK2 constitutively associated with pp95 protein (IR beta). Moreover, JAK2 also constitutively bound to a protein tyrosine phosphatase containing Src 2 regions (SHPTP2), but JAK1 did not. In HIRc cells expressing PTPase-negative mutant SHPTP2, no association of JAK2 with either pp185 or pp95 was detected. Thus, SHPTP2 might serve as an adapter protein linking between JAK2 and IRS. These results suggest that JAK1 and JAK2 behave differently and they may constitute a new regulatory component in insulin signaling.

[Evaluations of a specified number of inhalations and how to assess the contents in metered-dose inhalers]

Many kinds of Metered-Dose Inhalers (MDI) have been clinically available for bronchial asthma. Although manufacturers demonstrate the specified number of inhalations per canister on an attached document or on a plastic bag, the information provided are usually inadequate and inconsistent. They provide no information on the problems of the Metered-Dose Inhalers beyond the maximum specified number of actuations and the time when to exchange for a new one. We examined the technique how to evaluate the contents of MDI and their accuracy. Patients and their parents depended on inaccurate methods, such as shaking the inhalers to listen to the sound of contents, estimating the weight of the canisters and the size of emissions, and only a half of them were able to distinguish between 1/3 and 2/ 3 of remaining doses. Three Metered-Dose Inhalers with anti-inflammatory drugs and one MDI with beta-stimulant supplied consistent doses until they reached the maximum specified number. The 4 MDIs floated in the water in different ways and provided information when to replace for new ones in some MDIs.

IgE-anti-IgE-induced prostaglandin D2 release from cultured human mast cells

To elucidate the characterization of cultured human mast cells, the generation of prostaglandin D2 (PGD2) upon stimulation with IgE-anti IgE challenge was determined by using gas chromatography/mass spectrometry/selected ion monitoring (GC/MS/SIM) assay. Mononuclear cells obtained from human umbilical cord blood were cultured in the presence of Steel Factor, IL-6, and PGE2. After 8 weeks of culture, approximately 90 to 95% of cultured cells became tryptase-positive and included basophilic granules. At 12 weeks of culture, cells were harvested and incubated with 1 microgram/ml of human IgE for 1 hr and then challenged with 10 micrograms/ml of anti-IgE. The level of PGD2 release into the supernatant was measured by GC/MS/SIM with the stable isotope dilution method. Cyclooxygenase inhibitors affected the PGD2 release from the cell by IgE-anti IgE challenge incubation. Indomethacin inhibited 98% of PGD2 release. Acetylsalicylic acid (aspirin) and NS-398 (potent COX-2 inhibitor) also inhibited PGD2 release by 85 and 45% respectively.