MDM2 interacts with MDMX through their RING finger domains

The N-terminus of MDM2 proto-oncoprotein interacts with p53 and down modulates p53 activity by inhibiting transcriptional activity and promoting p53 degradation. MDMX is structurally related to MDM2 and also binds to p53. However, the function of MDMX has not been clarified yet. We found that MDM2 hetero-oligomerized with MDMX through their C-terminal RING finger domains. Yeast two-hybrid analysis revealed that the hetero-oligomerization between MDMX and MDM2 was more stable than the homo-oligomerization of each protein. MDM2 has been shown to be degraded by the ubiquitin-proteasome pathway, while MDMX was a stable protein. Interaction of MDMX with MDM2 through the C-terminal RING finger domains resulted in inhibiting degradation of MDM2. These data indicate that MDMX functions as a regulator of MDM2.

Analysis of thoracic duct flow waves using fast Fourier transform in sheep

We measured the lymph flow of the thoracic duct using an ultrasound transit-time flowmeter and then analyzed the obtained flow signals by fast Fourier transform. We found that the wave form included a low frequency component (approximately 0.1 Hz) as well as high frequency components which represented cordiac pulsation and respiratory movement. The low frequency component signified an intrinsic thoracic duct pulsation. When venous outflow pressure was increased, the frequency of the thoracic duct pulsation increased, whereas the frequencies of cardiac pulsation and respiratory movement were unchanged. These findings suggest that thoracic duct pulsation is independent of cardiac pulsation and respiratory movement.

Molecular cloning of human chondromodulin-I, a cartilage-derived growth modulating factor, and its expression in Chinese hamster ovary cells

Bovine chondromodulin-I (ChM-I) purified from fetal cartilage stimulated the matrix synthesis of chondrocytes, and inhibited the growth of vascular endothelial cells in vitro. The human counterpart of this bovine growth regulating factor has not been identified. We report here the cloning of human ChM-I precursor cDNA and its functional expression in Chinese hamster ovary (CHO) cells. We first identified a genomic DNA fragment which encoded the N-terminus of the ChM-I precursor, and then isolated human ChM-I cDNA from chondrosarcoma tissue by PCR. The deduced amino acid sequence revealed that mature human ChM-I consists of 120 amino acids. In total, 16 amino acid residues were substituted in the human sequence, compared to the bovine counterpart. Almost of all the substitutions were found in the N-terminal hydrophilic domain. In the C-terminal hydrophobic domain (from Phe42 to Val120), the amino acid sequence was identical except for Tyr90, indicating a functional significance of the domain. Northern blotting and in situ hybridization indicated a specific expression of ChM-I mRNA in cartilage. We also successfully determined the cartilage-specific localization of ChM-I protein, using a specific antibody against recombinant human ChM-I. Multiple transfection of the precursor cDNA into CHO cells enabled us to isolate the mature form of human ChM-I from the culture supernatant. Purified recombinant human ChM-I stimulated proteoglycan synthesis in cultured chondrocytes. In contrast, it inhibited the tube morphogenesis of cultured vascular endothelial cells in vitro and angiogenesis in chick chorioallantoic membrane in vivo.

[The in vitro properties of a new hydroxypyridone antimycotic rilopirox, with special reference to its anti-Candida activity]

In vitro properties of a new hydroxypyridone antimycotic rilopirox (RIL) with special reference to its anti-Candida activities were studied in comparison with the three reference drugs, ciclopirox olamine (CPO), oxiconazole nitrate (OCZ) and isoconazole nitrate (ICZ), using several strains of Candida albicans and Candida glabrata as the test organisms. RIL was potently fungicidal for growing cultures of these Candida strains, whereas all the three reference drugs were slightly fungicidal or fungistatic. Unlike OCZ and ICZ whose anti-Candida activity was decreased by lowering pH or adding serum to culture media, the activity of RIL was scarecely affected by change in pH or serum addition. However, RIL became less potent in the presence of Fe3+ at concentrations of 10(-5) mmol/ml or above. These findings suggest that RIL will be useful as a topical anti-Candida agent.

Protein interactions of Gts1p of Saccharomyces cerevisiae throughout a region similar to a cytoplasmic portion of some ATP-binding cassette transporters

The GTS1 gene product, Gts1p, has pleiotropic effects on the timing of budding, cell size, heat tolerance, sporulation and the lifespan of the yeast Saccharomyces cerevisiae. In this study, we found (using the yeast two-hybrid system) that Gts1p forms homodimers throughout the 18-amino acid region 296-313 which has considerable similarity to a region downstream of the Walker nucleotide-binding motif A of some ATP-binding cassette (ABC) transporters. The region contains two aspartic acid residues at 301 and 310 preceded by hydrophobic amino acid residues, and Gts1p with an Asp310 to Ala substitution showed considerably reduced homodimerization, as shown by the two-hybrid assay. Overexpression of the point-mutated Gts1p did not efficiently induce the Gts1p-related phenotypes described above, suggesting that the homodimerization of Gts1p is required for it to function in vivo. The C-terminal cytoplasmic domain of the yeast ABC transporters Mdl1p (multidrug resistance-like transporter) and Ycf1p (yeast cadmium factor or glutathione S-conjugate pump) bound to Gts1p in the two-hybrid system, and the heterodimerization activity of the Gts1p with the Asp301 to Ala substitution was more affected than the Gts1p with the Asp310 to Ala substitution. Overexpression of GTS1 considerably reduced, and disruption of GTS1 slightly decreased, cellular resistance to cycloheximide, cadmium, cisplatin and 1-chloro-2,4-dinitrophenol, which (except for cycloheximide) are all substrates of Ycf1p. These results suggest that Gts1p interacts with some ABC transporters through the binding site overlapping that of homodimerization and modulates their activity.

Radioresponse of thymomas verified with histologic response

Patterns of radiologic response of 10 thymomas treated by preoperative radiotherapy (RT) (18-20 Gy/2 weeks) were determined in conjunction with histologic response. Changes in tumor volume were evaluated with CT scans obtained 5 to 36 days before and 14 to 24 days after the initiation of RT and before surgery. The extent of tumor volume reduction (TR) varied widely (40-78%), while the mean daily volume decrement expressed as a percentage of the pre-RT tumor volume correlated significantly with the pre-RT tumor volume. Histologically, the tumors, all of which were resected 17 to 33 days after RT initiation, generally consisted of predominant fibrous tissues, rare necrotic foci, and few epithelial cells. The TR did not correlate with pre-RT tumor volume, observation period, histologic subtype, or quantity of remaining epithelial cells. The TR of thymomas does not predict RT impact on tumor cells but does reflect the quantity of inherent tumor stroma.

Pharmacological studies on the novel antiallergic drug HQL-79: I. Antiallergic and antiasthmatic effects in various experimental models

The effects of oral administration of 4-benzhydryloxy-1-[3-(1H-tetrazol-5-yl)-propyl]piperidine (HQL-79), a newly synthesized antiallergic drug, in various experimental allergic and asthmatic models were investigated. HQL-79 markedly inhibited immediate hypersensitivity reactions such as passive cutaneous anaphylaxis in rats, antigen-induced bronchoconstriction and nasal vascular permeability in actively sensitized guinea pigs, like epinastine and ketotifen did. Airway eosinophilia in repeatedly antigen-exposed guinea pigs was suppressed by chronic administration of HQL-79 for 2 weeks. In another experiment, the antigen-induced late asthmatic response (LAR) in metyrapone-treated guinea pigs was also ameliorated by chronic treatment with HQL-79. Moreover, HQL-79 partially inhibited the toluene diisocyanate-induced delayed-type hypersensitivity (DTH) reaction in mice when administered chronically during the immunization period. The corticosteroid dexamethasone inhibited the airway inflammatory responses in guinea pigs and the DTH in mice. These results indicate that HQL-79 has potent inhibitory effects on the immediate hypersensitivity reactions, and when administered chronically, it also inhibits airway eosinophilia, LAR and DTH, similarly to corticosteroids.

Pharmacological studies on the novel antiallergic drug HQL-79: II. Elucidation of mechanisms for antiallergic and antiasthmatic effects

The effects of 4-benzhydryloxy-1-[3-(1H-tetrazol-5-yl)-propyl]piperidine (HQL-79), a newly developed antiallergic drug, on various chemical mediators and on chemical mediator release were investigated. Orally administered HQL-79 strongly inhibited the histamine-induced skin reaction in rats, and histamine- and 5-hydroxytryptamine (5-HT)-induced bronchoconstriction in guinea pigs. HQL-79 inhibited antigen-induced release of leukotriene (LT) B4, LTC4, histamine and prostaglandin (PG) D2 from the chopped lung tissues of actively sensitized guinea pigs. On the other hand, release of PGE2, one of the bronchoprotective prostanoids, was significantly enhanced by HQL-79. In an in vivo experiment, chronic administration of HQL-79 clearly reduced PGD2 contents and enhanced PGE2 contents in the lungs of repeatedly antigen-exposed guinea pigs. In biochemical studies, HQL-79 inhibited mouse spleen PGD synthase in a concentration-dependent manner. None of the antiallergics such as epinastine, terfenadine, oxatomide and cetirizine inhibited the PGD synthase. HQL-79 did not affect PGE synthase in sheep vesicular gland microsomes. These results suggest that antiallergic and antiasthmatic effects of HQL-79 could be ascribed to antihistaminic- and anti-5-HT effects, chemical mediator release inhibition, PGE2-release enhancement and PGD synthase inhibition. It is considered, in particular, that the differential modulation of PGD2 and PGE2 production is a conspicuous pharmacological feature of HQL-79.

[A case of asynchronous renal cell carcinoma, hepatocellular carcinoma and residual ureteral cancer]

A case of asynchronous triple cancer in an 88-year-old male is reported. Six years ago, he had received left radical nephrectomy for renal cell carcinoma, and 2 years ago partial hepatectomy for hepatocellular carcinoma detected by follow-up computed tomography (CT). During the post-operative follow-up, no metastasis of either the renal or hepatic carcinoma was detected. On February 12, 1997 he presented with macroscopic hematuria. Cystoscopy revealed a tumor emerging from the left ureteral orifice, while CT and magnetic resonance imaging (MRI) revealed a tumor mass in the left exterior of bladder. Diagnosis of residual ureter tumor, we performed both left ureterectomy and partial cystectomy. Histological diagnosis revealed transitional cell carcinoma of the residual ureter (G2 > G3, pT1, pV0, pL0, pR0). Convalescence was uneventful and 10 months after the operation, he is alive with no recurrence or metastasis. We stress the importance of careful follow-up not only to perceive the recurrence or metastasis of renal cancer but also to detect cancer in other parts of the body.

Enantioselective tissue distribution of the basic drugs disopyramide, flecainide and verapamil in rats: role of plasma protein and tissue phosphatidylserine binding

PURPOSE

The stereoselective distribution of three basic drugs, disopyramide (DP), flecainide (FLC) and verapamil (VP), was studied to clarify the relationship between the tissue-to-unbound plasma concentration ratio (Kpf) and drug lipophilicity and binding to phosphatidylserine phs), which are possible factors determining the tissue distribution of these drug enantiomers.

METHODS

The drug enantiomer or racemate was administered to rats by intravenous constant infusion. Their concentrations in plasma and tissues were determined using enantioselective high-performance liquid chromatography. Plasma protein binding, and buffer-octanol and buffer-hexane containing PhS partition coefficients were also determined.

RESULTS

The stereoselectivity of the tissue-to-plasma concentration ratio (Kp) was partly associated with that of serum protein binding. However, the Kpf value of R(+)-VP in the lung was significantly higher than that of S(-)-VP. A linear correlation was observed between the Kpf values of these drug enantiomers in brain, heart, lung and muscle, and their buffer-hexane containing PhS partition coefficients. The in vitro data for the binding of these drugs to PhS suggest that stereoselective binding of VP to PhS may correspond to its stereoselective tissue binding.

CONCLUSIONS

Our findings provide some evidence for a role of tissue PhS in the tissue distribution of basic drugs with respect to stereoselectivity of drug enantiomers distribution.

L-selectin-specific autoantibodies in murine lupus: possible involvement in abnormal homing and polarization of CD4+ T cell subsets

One notable functional abnormality in murine and human systemic lupus erythematosus (SLE) is the defect in the production of IL-2 in association with the deficit in naive CD4+ T cells. The mechanism is unknown, but one idea is that naturally occurring autoantibodies with specificities to the naive CD4+ T cell subpopulation are related to this event. We selected hybridoma monoclonal autoantibodies from SLE-prone (New Zealand Black (NZB) x New Zealand White (NZW))F1 mice that reacted with restricted populations of CD4+ T cells. One of these, H32, was specific for L-selectin, as determined by 1) distribution of Ag H32 on lymphoid cells similar to Mel-14, an epitope of L-selectin; 2) shedding of 80-kDa molecules with epitope H32 from the surface of lymph node cells coincidentally with Mel-14, when stimulated with phorbol ester; 3) cross-inhibitory activities on Ag binding between H32 and Mel-14; and 4) reactivity of H32 with recombinant mouse L-selectin. Pretreatment of 51Cr-labeled lymphocytes from BALB/c mice with H32 significantly inhibited their homing to lymph nodes in vivo. The BALB/c splenic H32+ CD4+ T cell subset produced few cytokines except IL-2, thus corresponding to naive ThP-type cells. This subset was markedly selectively depleted in aged (NZB x NZW)F1 mice. There was an age-associated increase in frequencies and titers of anti-L-selectin autoantibodies in sera from (NZB x NZW)F1 mice. Thus, abnormalities of naive CD4+ T cell subset, including IL-2 production in subjects with SLE, are at least partly attributed to the generation of autoantibodies to L-selectin.

Suppression of prostanoid formation and regulation of peripheral circulation after surgery using thrombin inhibitor (MD805)

We studied the effects of thrombin generation due to surgical stress on prostanoid formation and peripheral circulation in anesthetized dogs. Three experimental groups were used, consisting of a control group (group 1), a thoracotomized group (group 2), and a thoracotomized group treated with thrombin inhibitor (MD805: a synthetic arginine derivative) (group 3). The plasma concentrations of thrombin-antithrombin III complex (TAT) and prostanoids were measured along with the hemodynamic parameters. The plasma concentrations of TAT and thromboxane B2 significantly increased 1h after a thoracotomy in group 2. However, neither concentration increased after a thoracotomy in group 3. The flow ratio of the brachial and femoral arteries to cardiac output significantly decreased 1h after a thoracotomy in group 2. This study indicates that thromboxane A2 was thus synthesized by the stimulation of endogenous thrombin, while it also reduced the peripheral blood flow after surgery.

Quantitative determination of disopyramide, verapamil and flecainide enantiomers in rat plasma and tissues by high-performance liquid chromatography

Enantiomers of disopyramide (DP), flecainide (FLC) and verapamil (VP) were extracted from rat plasma and tissues (brain, lung, heart, liver, kidney and muscle), followed by quantitative determination using enantioselective high-performance liquid chromatography with chiral stationary-phase columns. The recoveries of S-(+)- and R-(-)-DP from tissues were higher than 69%, and the within- and between-day coefficients of variation were very low (0.5 - 5.7%). The lower limits of detection in each tissue were less than 289 ng/g tissue. The recoveries of S-(+)- and R-(-)-FLC from tissues were higher than 88%, and the within- and between-day coefficients of variation were 1.2-6.0%. The lower limits of detection in each tissue were less than 37 ng/g tissue. The recoveries of S-(-)- and R-(+)-VP from tissues were higher than 80%, and the within- and between-day coefficients of variation were 0.5-6.2%. The lower limits of detection in each tissue were less than 51 ng/g tissue. The analytical methods established in this study will be suitable for determining the concentrations of the enantiomers of these anti-arrhythmic agents in rat plasma and tissues.

Contribution of tryptophan residues to the structural changes in perfringolysin O during interaction with liposomal membranes

Perfringolysin O (theta-toxin) is a cholesterol-binding and pore-forming toxin that shares with other thiol-activated cytolysins a highly conserved sequence, ECTGLAWEWWR (residues 430-440), near the C-terminus. To understand the membrane-insertion and pore-forming mechanisms of the toxin, we evaluated the contribution of each Trp to the toxin conformation during its interaction with liposomal membranes. Circular dichroism (CD) spectra of Trp mutant toxins indicated that only Trp436 has a significant effect on the secondary structure, and that Trp436, Trp438, and Trp439 make large contributions to near-UV CD spectra. Quenching the intrinsic Trp fluorescence of the wild-type and mutant toxins with brominated lecithin/cholesterol liposomes revealed that Trp438 and probably Trp436, but not Trp439, contributes to toxin insertion into the liposomal membrane. Near-UV CD spectra of the membrane-associated mutant toxins indicated that both Trp438 and Trp439 are required for the CD peak shift from 292 to 300 nm, a signal related to theta-toxin oligomerization and/or pore formation, suggesting a conformational change around Trp438 and Trp439 in these processes.

The GTS1 gene product influences the ultradian oscillation of glycolysis in cell suspension of the yeast Saccharomyces cerevisiae

We tested the effect of the GTS1 gene of the yeast Saccharomyces cerevisiae on the cyanide-induced ultradian oscillation of the glycolytic metabolite NADH in cell suspension of strains with different copy numbers of the gene, that is, the wild-type, GTS1-disrupted and GTS1-overexpressing strains. The cells showed long-lasting oscillations when harvested between 1 and 2 hours after the diauxic shift from glucose to ethanol as a growth substrate. The frequencies of oscillation did not vary very much among the three strains tested. However, the amplitudes and durations of the oscillation were changed significantly as a function of the GTS1 gene-dosage. The effect of GTS1 on the amplitude was not caused by changing rates of glucose incorporation into cells as the rates were the same among the three strains during the macroscopic oscillation.

Hemodynamic changes in hepatic artery after glucose ingestion in healthy subjects and patients with cirrhosis

PURPOSE

The purpose of this study was to investigate hemodynamic changes in the hepatic artery after glucose ingestion.

METHODS

We used color Doppler sonography to measure hemodynamic changes in the right hepatic artery and the right portal vein in response to glucose ingestion (225 ml, 300 kcal) in 25 healthy subjects and 25 patients with cirrhosis.

RESULTS

In healthy subjects, the peak systolic and end-diastolic velocities in the right hepatic artery decreased (33 +/- 3% and 53 +/- 3%) from baseline velocities measured in the fasting state. The resistance index of the right hepatic artery and the velocity in the right portal vein in these subjects significantly (p < 0.01) increased (14 +/- 2% and 32 +/- 2%) from baseline values after glucose ingestion. Glucose ingestion produced significantly (p < 0.01) smaller changes in cirrhotic patients. The maximum decrease in the peak systolic and end-diastolic velocities in the right hepatic artery were 13 +/- 2% and 25 +/- 3% from baseline velocities, and the maximum increases in the resistance index of the right hepatic artery and the velocity in the right portal vein were 6 +/- 1% and 10 +/- 3% from baseline values.

CONCLUSIONS

The decrease in blood flow velocity in the right hepatic artery after glucose ingestion is presumably a homeostatic mechanism to maintain constant hepatic perfusion. This reciprocal response was reduced in cirrhotic patients.

Cell cycle arrest and apoptosis of leukemia cells induced by L-asparaginase

Apoptotic cell death of murine leukemia cells induced by E. coli L-asparaginase was studied. Deprivation of L-asparagine from the culture of L5178Y cells by L-asparaginase caused the fragmentation of chromosomal DNA of the leukemia cells within 24 h. Prior to the degradation of DNA, cell cycles of L5178Y cells were found to be arrested in G1 phase, and evidence of the DNA strand breaks was initially observed in G1 phase cells as early as 8 h after the asparaginase treatment. Therefore, apoptosis of leukemia cells induced by L-asparaginase is an event that is associated with the cell cycle arrest in G1 phase.

Cloning and characterization of novel CIS family genes

We have reported two JAK-signaling modulators, CIS (cytokine-inducible SH2 protein) and JAB (JAK2 binding protein), which are structurally related. Here we cloned three additional CIS family genes (CIS2, CIS3, and CIS4) on the basis of an expression sequence tag (EST) database search. We also found at least two additional candidates of this gene family in the database. These genes were induced by erythropoietin and granulocyte-macrophage colony stimulating factor in certain hematopoietic cell lines. The SH2 domain and a C-terminal 40 amino acid region, designated the CIS homology domain (CH domain), are highly conserved in this family, while the N-terminal regions of these proteins share little similarity. A yeast two-hybrid assay and in vitro and in vivo binding assays revealed that in addition to JAB, CIS3 bound to the JAK2 tyrosine kinase domain (JH1), although the interaction of CIS3 with the JAK2-JH1 domain was much weaker than that of JAB. Transient expression of JAB and CIS3, but not other CISs, strongly inhibited leukemia inhibitory factor (LIF)-induced STAT3-reporter gene activation in 293 cells. Furthermore, constitutive overexpression of JAB and CIS3 in M1 leukemia cells prevented LIF-induced differentiation and growth arrest. Although the physiological function remains to be investigated, CIS family genes could play a role in the negative regulation of cytokine signaling by interacting with specific targets.

A new protein containing an SH2 domain that inhibits JAK kinases

The proliferation and differentiation of cells of many lineages are regulated by secreted proteins known as cytokines. Cytokines exert their biological effect through binding to cell-surface receptors that are associated with one or more members of the JAK family of cytoplasmic tyrosine kinases. Cytokine-induced receptor dimerization leads to the activation of JAKs, rapid tyrosine-phosphorylation of the cytoplasmic domains, and subsequent recruitment of various signalling proteins, including members of the STAT family of transcription factors, to the receptor complex. Using the yeast two-hybrid system, we have now isolated a new SH2-domain-containing protein, JAB, which is a JAK-binding protein that interacts with the Jak2 tyrosine-kinase JH1 domain. JAB is structurally related to CIS, a cytokine-inducible SH2 protein. Interaction of JAB with Jak1, Jak2 or Jak3 markedly reduces their tyrosine-kinase activity and suppresses the tyrosine-phosphorylation and activation of STATs. JAB and CIS appear to function as negative regulators in the JAK signalling pathway.

CIS, a cytokine inducible SH2 protein, is a target of the JAK-STAT5 pathway and modulates STAT5 activation

We searched for immediate early cytokine responsive genes and isolated a novel gene, CIS (Cytokine Inducible SH2 containing protein) that is induced in hematopoietic cells by a subset of cytokines including interleukin-2 (IL-2), IL-3, and erythropoietin (EPO). The mutant IL-2 receptor that fails to activate STAT5 could not induce CIS, suggesting that STAT5 is involved in the cytokine-inducible expression of CIS. We cloned the 5'-flanking region of the CIS gene and found that about 200 bases upstream of the transcription-initiation site contain four potential STAT5 binding sites (MGF boxes). Luciferase reporter assays showed that these MGF boxes were essential for EPO-dependent promoter activity. Expression of STAT5 and the EPO receptor in HEK293 cells conferred EPO-dependent activation of the CIS promoter. These data indicate that CIS is a target of the JAK-STAT5 pathway of cytokine receptors. CIS contains an SH2 domain and binds to tyrosine-phosphorylated EPO and IL-3 receptors. In HEK293 cells expressing STAT5 and the EPO receptor, EPO-dependent tyrosine phosphorylation of STAT5, as well as EPO-dependent CIS-promoter activation, was suppressed when CIS was coexpressed. Moreover, the induction of oncostatin M, another STAT5 target, as well as the tyrosine-phosphorylation of STAT5, were partially suppressed by CIS expression in Ba/F3 cells. Thus, CIS is a feedback modulator of STAT5; its expression is induced by STAT5 and it negatively modulates STAT5 activation.

[In vitro antifungal activity of rilopirox, a new hydroxypyridone antimycotic agent]

In vitro antifungal activities of rilopirox (RIL), a new topical hydroxypyridone antifungal agent, were studied against 7 species (31 strains) of yeast-like fungi and 15 species (17 strains) of mycerial fungi from stock cultures of a wide range of medically important fungi. Tests were carried out by the liquid dilution method using Neopeptone dextrose broth with ciclopirox olamine (CPO) and oxiconazole nitrate (OCZ) as reference drugs. RIL exhibited a broad spectrum of antifungal activities; the MIC of RIL against yeasts were about 1 microgram/ml, those against other fungi were 0.5-4 micrograms/ml. Antifungal activities were similar to CPO, and compare to OCZ, RIL showed characteristically little differences in its activities against different species or strains of target organisms.