Application of near-infrared time-resolved spectroscopy to rat liver--a preliminary report for surgical application

The applicability of near-infrared time-resolved spectroscopy to rat liver surgery was investigated. First, the technical reliability in determining the absorption coefficient (mu(a)) and reduced scattering coefficient (mu'(s)) of the liver was checked. Next, boundary effects in determining mu(a) and mu'(s) of the rat liver were examined. Finally, changes in mu(a) and mu'(s) of rat liver with ischaemia were directly measured by TRS. Our TRS system showed that the mu(a) value held a linear correlation with the ink concentration in a lipid emulsion until mu(a) reached 1.2 cm(-1), while the mu'(s) was fairly independent. The mu(a) values of blood-free rat liver and blood-containing rat liver at 780 nm were observed to be 0.43 cm(-1) and 0.67 cm(-1) by using the matching method, indicating that TRS is reliable in determining mu(a) and mu'(s) of the liver. Possible errors in mu(a) and mu'(s) determination due to the boundary effects of the rat liver were as small as 7%, when the mu(a) value was as high as observed for the liver. The oxygen saturation of haemoglobin (SO2) was changed from 64.9% to 8.0%, and the haemoglobin content (THB) from 189.1 microM to 131.6 microM by ischaemia. Mu'(s) dynamically changed in the range 7.06 cm(-1) to 11.36 cm(-1). We conclude that time-resolved measurement is applicable in the high-mu(a) region observed in the liver, and can give quantitative estimations of SO2 and THB in the liver.

Role of platelet-activating factor acetylhydrolase gene mutation in Japanese childhood IgA nephropathy

Platelet-activating factor (PAF) is a potent mediator of inflammatory injury in renal diseases. PAF is degraded to inactive products by PAF acetylhydrolase. Recently, a point mutation (G to T transversion) of the PAF acetylhydrolase gene was observed at position 994, and this mutation was found to contribute to the variability in plasma PAF levels, with undetectable plasma PAF acetylhydrolase activity occurring in homozygous patients (TT genotype) and reduced levels of activity in heterozygous patients (GT genotype). Therefore, we investigated the effect of the PAF acetylhydrolase gene mutation on the pathogenesis and progression of immunoglobulin A (IgA) nephropathy. Genomic DNA was obtained from 89 children with IgA nephropathy and 100 controls. We identified the PAF acetylhydrolase gene mutation (G994T) by polymerase chain reaction. There was no significant difference in genotypic frequency between patients and controls. However, urinary protein excretion at the time of biopsy was significantly greater in patients with the GT/TT genotypes than in those with the GG genotype. The percentage of glomeruli with mesangial cell proliferation was significantly greater in patients with the GT/TT genotypes than in those with the GG genotype. These results indicate the PAF acetylhydrolase gene mutation may influence the degree of proteinuria and the extent of mesangial proliferation in the early stage of childhood IgA nephropathy.

Role of lecithin-cholesterol acyltransferase in the metabolism of oxidized phospholipids in plasma: studies with platelet-activating factor-acetyl hydrolase-deficient plasma

To determine the relative importance of platelet-activating factor-acetylhydrolase (PAF-AH) and lecithin-cholesterol acyltransferase (LCAT) in the hydrolysis of oxidized phosphatidylcholines (OXPCs) to lyso-phosphatidylcholine (lyso-PC), we studied the formation and metabolism of OXPCs in the plasma of normal and PAF-AH-deficient subjects. Whereas the loss of PC following oxidation was similar in the deficient and normal plasmas, the formation of lyso-PC was significantly lower, and the accumulation of OXPC was higher in the deficient plasma. Isolated LDL from the PAF-AH-deficient subjects was more susceptible to oxidation, and stimulated adhesion molecule synthesis in endothelial cells, more than the normal LDL. Oxidation of 16:0-[1-14C]-18:2 PC, equilibrated with plasma PC, resulted in the accumulation of labeled short- and long-chain OXPCs, in addition to the labeled aqueous products. The formation of the aqueous products decreased by 80%, and the accumulation of short-chain OXPC increased by 110% in the deficient plasma, compared to the normal plasma, showing that PAF-AH is predominantly involved in the hydrolysis of the truncated OXPCs. Labeled sn-2-acyl group from the long-chain OXPC was not only hydrolyzed to free fatty acid, but was preferentially transferred to diacylglycerol, in both the normal and deficient plasmas. In contrast, the acyl group from unoxidized PC was transferred only to cholesterol, showing that the specificity of LCAT is altered by OXPC. It is concluded that, while PAF-AH carries out the hydrolysis of mainly truncated OXPCs, LCAT hydrolyzes and transesterifies the long-chain OXPCs.

1q23 gain is associated with progressive neuroblastoma resistant to aggressive treatment

Neuroblastoma is one of the most common malignant tumors of childhood and is characterized by regressive and progressive disease. Genetic factors that define progression of neuroblastomas are still unknown. We performed comparative genomic hybridization (CGH) on 27 neuroblastomas and dual-color fluorescence in situ hybridization (FISH) to identify genetic aberrations associated with progressive neuroblastoma showing resistance to aggressive treatment. 17q21-q25 gains and MYCN amplification were associated with stage 4 neuroblastomas; however, these genetic aberrations had no significant relation to the progression of stage 4 neuroblastomas. A novel chromosomal gain at 1q21-q25 was found in 8 of 16 cases (50%) of stage 4 neuroblastoma. Gain of 1q21-q25 was observed in all of the progressive cases (8/8), which showed resistance to chemotherapy, including 5 fatal neuroblastomas in stage 4, whereas 1q21-q25 gain was not found in any of the 8 remission cases in stage 4. Survival analysis also showed that 1q21-q25 gain was associated with a poor outcome. High xenotransplantability in nude mice was observed for the tumors with 1q21-q25 gain (4/5; 80%). These data show that 1q21-q25 gain is strongly associated with progression of stage 4 neuroblastoma. Furthermore, by dual-color FISH analysis using cosmid clones, the 1q21-q25 gain was narrowed to increase in DNA copy number on 1q23 in the fatal type of stage 4 neuroblastoma showing this gain. These results suggest that DNA amplification at 1q23 may play a role in the development of progressive neuroblastoma in an advanced stage.

All ApoB-containing lipoproteins induce monocyte chemotaxis and adhesion when minimally modified. Modulation of lipoprotein bioactivity by platelet-activating factor acetylhydrolase

Mildly oxidized LDL has many proinflammatory properties, including the stimulation of monocyte chemotaxis and adhesion, that are important in the development of atherosclerosis. Although ApoB-containing lipoproteins other than LDL may enter the artery wall and undergo oxidation, very little is known regarding their proinflammatory potential. LDL, IDL, VLDL, postprandial remnant particles, and chylomicrons were mildly oxidized by fibroblasts overexpressing 15-lipoxygenase (15-LO) and tested for their ability to stimulate monocyte chemotaxis and adhesion to endothelial cells. When conditioned on 15-LO cells, LDL, IDL, but not VLDL increased monocyte chemotaxis and adhesion approximately 4-fold. Chylomicrons and postprandial remnant particles were also bioactive. Although chylomicrons had a high 18:1/18:2 ratio, similar to that of VLDL, and should presumably be less susceptible to oxidation, they contained (in contrast to VLDL) essentially no platelet-activating factor acetylhydrolase (PAF-AH) activity. Because PAF-AH activity of lipoproteins may be reduced in vivo by oxidation or glycation, LDL, IDL, and VLDL were treated in vitro to reduce PAF-AH activity and then conditioned on 15-lipoxygenase cells. All 3 PAF-AH-depleted lipoproteins, including VLDL, exhibited increased stimulation of monocyte chemotaxis and adhesion. In a similar manner, lipoproteins from Japanese subjects with a deficiency of plasma PAF-AH activity were also markedly more bioactive, and stimulated monocyte adhesion nearly 2-fold compared with lipoproteins from Japanese control subjects with normal plasma PAF-AH. For each lipoprotein, bioactivity resided in the lipid fraction and monocyte adhesion could be blocked by PAF-receptor antagonists. These data suggest that the susceptibility of plasma lipoproteins to develop proinflammatory activity is in part related to their 18:1/18:2 ratio and PAF-AH activity, and that bioactive phospholipids similar to PAF are generated during oxidation of each lipoprotein. Moreover, LDL, IDL, postprandial remnant particles, and chylomicrons and PAF-AH-depleted VLDL all give rise to proinflammatory lipids when mildly oxidized.

High-level expressing YAC vector for transgenic animal bioreactors

The position effect is one major problem in the production of transgenic animals as mammary gland bioreactors. In the present study, we introduced the human growth hormone (hGH) gene into 210-kb human alpha-lactalbumin position-independent YAC vectors using homologous recombination and produced transgenic rats via microinjection of YAC DNA into rat embryos. The efficiency of producing transgenic rats with the YAC vector DNA was the same as that using plasmid constructs. All analyzed transgenic rats had one copy of the transgene and produced milk containing a high level of hGH (0.25-8.9 mg/ml). In transgenic rats with the YAC vector in which the human alpha-lactalbumin gene was replaced with the hGH gene, tissue specificity of hGH mRNA was the same as that of the endogenous rat alpha-lactalbumin gene. Thus, the 210-kb human alpha-lactalbumin YAC is a useful vector for high-level expression of foreign genes in the milk of transgenic animals.

Ca2+/calmodulin-dependent protein kinase II inhibitors potentiate superoxide production in polymorphonuclear leukocytes

The possible role of Ca2+/calmodulin-dependent protein kinase II (CaMK II) in superoxide anion (O2-) production induced by formyl-methionyl-leucyl-phenylalanine (FMLP) was investigated in mouse polymorphonuclear leukocytes (PMNs). KN-93 and KN-62, specific CaMK II inhibitors, augmented FMLP-induced O2- production. KN-92, an analogue which did not inhibit CaMK II, did not affect O2- production. W-7, a calmodulin inhibitor, augmented O2- production when administered at 30 mM for 5 min. KN-93 and recombinant mouse tumour necrosis factor-alpha (rmTNF-alpha) each augmented the maximal production of O2- induced by FMLP, and an additive effect of a combination of KN-93 and rmTNF-alpha was observed. CaMK II activity in the PMNs was increased by FMLP, and the increase was inhibited by KN-93 but not by rmTNF-alpha. These results suggest that the inhibition of CaMK II resulted in the augmentation of FMLP-induced O2- production in PMNs by a mechanism different from that of the augmentation shown by TNF-alpha.

Functional analysis of poly(ADP-ribose) polymerase in Drosophila melanogaster

Poly(ADP-ribose) polymerase (PARP) is conserved in eukaryotes. To analyze the function of PARP, we isolated and characterized the gene for PARP in Drosophila melanogaster. The PARP gene consisted of six translatable exons and spanned more than 50 kb. The DNA binding domain is encoded by exons 1-4. Although the consensus cleavage site of CED-3 like protease during apoptosis is conserved from human to Xenopus laevis PARPs, it is neither conserved in the corresponding region of Drosophila nor Sarcophaga peregrina. There are two cDNAs species in Drosophila. One cDNA could encode the full length PARP protein (PARP I), while the other is a truncated cDNA which could encode a partial-length PARP protein (PARP II), which lacks the automodification domain and is possibly produced by alternative splicing. The expression of these two forms of PARP in E. coli demonstrated that while PARP II has the catalytic NAD-binding domain and DNA-binding domain it is enzymatically inactive. On the other hand PARP I is active. A deletion mutant of PARP gene could grow to the end of embryogenesis but did not grow to the adult fly. These results suggest that the PARP gene plays an important function during the development of Drosophila.

Tissue distribution of polaprezinc in rats determined by the double tracer method

The tissue distribution of polaprezinc (an insoluble zinc complex of L-carnosine) in rats was studied by the double tracer method using [U-14C-histidine]-, 65Zn-polaprezinc. The 65Zn-radioactivity was measured with an auto-gamma counter, and the 14C containing 65Zn was converted to an absolute count according to the calibration curve for quenching with a liquid scintillation counter with the spill-over method. After the administration of 14C-, 65Zn-polaprezinc to rats, the excretion ratio and time courses in the tissues of the 14C-and 65Zn-radioactivity were different each other. We found that polaprezinc was metabolized as endogenous amino acid or zinc after dissociation in the body. The zinc concentration in plasma reached its maximum at 1 h and decreased slowly, returning to the endogenous level at 11 h after the administration of non-labeled polaprezinc. The concentrations of zinc in liver, kidney, testis, prostate, and cerebrum remained rather constant. The replacement ratios of 65Zn to zinc in the tissues at its maximum percentage were 40% in plasma, 16-20% in liver, kidney, blood, and prostate. The low replacement ratios in testis and cerebrum (2-3%) suggested that zinc uptakes in testis and brain were regulated by the blood-testis-barrier and blood-brain-barrier, respectively.

Contribution of endothelin-1 to microcirculatory impairment in total hepatic ischemia and reperfusion injury

BACKGROUND

Endothelin (ET)-1 may have a role in hepatic polymorphonuclear leukocyte infiltration as well as microcirculatory disturbance during hepatic ischemia-reperfusion (HIR) injury. This study was conducted to investigate the influence of ET-1 on the hepatic microcirculation after total HIR and to evaluate the effect of a nonselective ET receptor antagonist under these conditions.

METHODS

Male rats pretreated with either normal saline (NS group) or TAK-044, a nonselective ET receptor antagonist (TAK group), were subjected to 120 min of total hepatic ischemia with extracorporeal portosystemic shunting.

RESULTS

Plasma ET-1 levels increased significantly from 1 to 6 hr after reperfusion in the NS group when compared with the nonischemic control. In the early phase of reperfusion, the NS group showed significantly narrower sinusoids, lower hepatic tissue blood flow, a lower hepatic tissue oxy-hemoglobin concentration, and more hepatic neutrophil infiltration than the TAK group (P<0.05). Pretreatment with TAK-044 improved hepatic microcirculatory derangement, and resulted in significantly better 7-day survival (61.5%) with more bile production after reperfusion when compared with the NS group (P<0.01).

CONCLUSIONS

The present study demonstrated that ET-1 is involved in the development of HIR injury by causing deterioration of the hepatic microcirculation. A nonselective ET receptor antagonist successfully ameliorated HIR injury through improvement of hepatic oxygenation and of the microcirculation along with reduced hepatic neutrophil infiltration.

Poly(ADP-ribose) polymerase interacts with novel Drosophila ribosomal proteins, L22 and l23a, with unique histone-like amino-terminal extensions

Poly(ADP-ribose) polymerase (PARP) is a nuclear enzyme that recognizes and binds to the nicks and ends of DNA, and catalyses successive ADP-ribosylation reactions. To clarify the function of PARP at the molecular level, we searched proteins which interact with PARP. In the auto-modification domain of PARP in Drosophila, there is a putative leucine-zipper motif which can interact with other protein molecules. To find interacting proteins we examined the auto-modification domain of Drosophila PARP, using the Far-Western screening method. From six independent cDNA clones isolated, we characterized two clones, PBP-3 and PBP-12. The predicted amino acid sequences from 109 to 269 of PBP-3 and from 184 to 312 of PBP-12 had more than 62% identities to mammalian L23a (rpl23a) and L22 (rpl22), the ribosomal proteins of the large subunit. This indicated that PBP-3 and PBP-12 are Drosophila homologues of L23a and L22, respectively. These Drosophila ribosomal protein L22 and L23a have additional Ala-, Lys- and Pro-rich sequences at the amino terminus, which have a resemblance to the carboxy-terminal portion of histone H1. Thus, Drosophila L22 and L23a might have two functions, namely the role of DNA-binding similar to histone H1 and the role of organizing the ribosome.

Human T-cell leukemia virus type 1 can infect a wide variety of cells in mice

Analysis of human T-cell leukemia virus type 1 (HTLV-1)-infected cell types and the interplay of these infected cells in vivo should provide valuable information to elucidate the pathogenesis of HTLV-1-associated diseases in humans and in animal models. In this study, HTLV-1-infected cell types were identified in HTLV-1-infected C3H/HeJ mice. Pan T, CD4+, CD8+, granulocyte and pan B cell fractions in the splenocytes of MT-2 cell-inoculated mice were sorted by use of their cell surface high-density expression of CD3e, CD4, CD8, Gr-1 and B220 antigens, respectively, with a fluorescence-activated cell sorter. The pX sequence of HTLV-1 provirus in the lysate of each fraction was amplified by polymerase chain reaction and detected by Southern hybridization. Interestingly, in addition to the CD4+ cell fraction, the pX sequence was also found in CD8+ cell, B cell and granulocyte fractions. The broad cell spectrum of HTLV-1 infection in mice is consistent with the situation in humans. Our finding indicate that HTLV-1 receptor or coreceptor is widely distributed among different cell types in mice.

Platelet-activating factor acetylhydrolase gene mutation in Japanese nephrotic children

BACKGROUND

Platelet-activating factor (PAF) may be involved in the pathogenesis of steroid-responsive nephrotic syndrome (SRNS). PAF is degraded to inactive products by PAF acetylhydrolase. We have investigated whether PAF acetylhydrolase gene mutation is involved in SRNS in Japanese children.

METHODS

We identified a point mutation in the PAF acetylhydrolase gene (G994T) using the polymerase chain reaction in 101 Japanese children with SRNS and 100 healthy Japanese.

RESULTS

There was no difference in the genotype and allele frequencies between patients with SRNS and normal controls. The mean number of relapses during the first year after onset was significantly higher in the 26 patients who were heterozygous for the mutant allele (GT) than in 75 wild-type homozygotes (GG) (2.61 +/- 1.98 vs. 1.33 +/- 1.35; P = 0.0019).

CONCLUSIONS

We conclude that analysis of the PAF acetylhydrolase gene mutation at position 994 in Japanese children with SRNS allows the identification of patients who are more likely to have a disease relapse.

Expression of alpha-fetoprotein and prostate-specific antigen genes in several tissues and detection of mRNAs in normal circulating blood by reverse transcriptase-polymerase chain reaction

BACKGROUND

alpha-Fetoprotein (AFP) and prostate-specific antigen (PSA) in serum are widely used as tumor markers in the evaluation of prognosis and management of patients with hepatocellular carcinoma and prostate cancer, respectively. To establish the molecular diagnosis of cancer, reverse transcriptase polymerase chain reaction (RT-PCR) for AFP and PSA was used to identify circulating cancer cells in the blood of cancer patients. Here, we examined the tissue-specificity of AFP and PSA and tested whether AFP and PSA are suitable targets in the detection of certain cancer cells by RT-PCR using peripheral blood samples.

METHODS

Tissue specificity of AFP and PSA was analyzed by Northern blotting and RT-PCR. Probes for AFP and PSA were hybridized with poly A+ RNAs from 50 human tissues. RT-PCR for AFP and PSA mRNA was performed using several cancerous tissues and normal tissues and peripheral blood cells from seven healthy volunteers.

RESULTS

Broad expression of AFP was observed in several tissues and a large amount of AFP mRNA was found in fetal liver. PSA was expressed in prostate, salivary gland, pancreas and uterus. By RT-PCR, AFP and PSA mRNA were detected in several tumors, including salivary pleomorphic adenoma, hilar bile duct carcinoma, pancreatic carcinoma, transitional cell carcinoma of urinary bladder and thyroid papillary carcinoma. Furthermore, AFP and PSA mRNAs were frequently detected by RT-PCR, even in peripheral blood cells from healthy volunteers.

CONCLUSIONS

Neither AFP nor PSA showed tissue-specific expression. AFP and PSA mRNA were detected in several diseased and non-diseased tissues and normal circulating blood by RT-PCR.

An alternative form of poly(ADP-ribose) polymerase in Drosophila melanogaster and its ectopic expression in rat-1 cells

We here report an alternatively spliced form of PARP lacking exon 5 of the Drosophila PARP gene encoding the auto-modification domain. The alternative form of PARP (PARP II) consists 804 amino acids with a molecular weight of 92.3 kDa. The deduced amino acid sequence of PARP II was completely matched to that of PARP I encoded by a full-length Drosophila PARP cDNA, except it lacks the region corresponding to the auto-modification domain. To examine the function of PARP II, stable transformants of Rat-1 cells in which PARP II was ectopically expressed by MMTV-LTR were isolated and characterized. After induction with dexamethasone, PARP II transformants showed slower growth and showed morphological changes with loss of spindled shape compared to cells transformed with the vector or PARP I. The PARP II-transformed cells incorporated propidium iodide after induction; however, Annexin V and TUNEL analysis indicated these changes were not due to apoptosis.

Effects of L-carnitine supplementation on muscular symptoms in hemodialyzed patients

Various muscle symptoms are well recognized among patients on maintenance hemodialysis. Carnitine deficiency may be an important factor of dialysis-associated muscle symptoms, whereas high-dose L-carnitine supplementation may result in unphysiologically high plasma levels of carnitine and carnitine esters. We studied the effect of low-dose L-carnitine treatment (500 mg/d) on muscle symptoms, plasma carnitine fractions, and lipid profiles in 30 periodically dialyzed patients with muscular weakness, fatigue, or cramps/aches. After 12 weeks of L-carnitine treatment, about two-thirds of patients had at least some improvement in muscular symptoms, whereas carnitine fractions were normal or slightly above normal ranges, but lipid profiles showed no demonstrable changes. This study also showed the correlation between plasma-free carnitine deficiency and months on dialysis. These results suggest that prolonged low-dose L-carnitine treatment can improve dialysis-associated muscle symptoms by restoring carnitine tissue levels and washing out acyl moieties.

[Serum factors in cancer patients affecting the antitumor effect of 5-fluorouracil]

A human colon cancer cell line, HCT-15, was found to proliferate in human sera. Sera of cancer patients undergoing continuous intravenous administration of 5-fluorouracil (5-FU) were tested for the antitumor effect by counting HCT-15 cells stained with Giemsa solution. 5-FU concentrations in those sera were not correlated with the antitumor effects. After HCT-15 cells were incubated in sera of cancer patients or healthy volunteers for 24 hours followed by removal of those sera, those cells were incubated in a culture medium containing 500 or 1000 ng/ml of 5-FU for 48 hours. It was shown that preincubation of HCT-15 cells with sera of cancer patients but not sera of healthy volunteers decreased the sensitivity of HCT-15 cells to 5-FU. These results suggest that there may be some factors in the serum of a cancer patient, which affect the antitumor effect of 5-FU.

Design of a novel oral fluoropyrimidine carbamate, capecitabine, which generates 5-fluorouracil selectively in tumours by enzymes concentrated in human liver and cancer tissue

Capecitabine (N4-pentyloxycarbonyl-5'-deoxy-5-fluorocytidine) is a novel oral fluoropyrimidine carbamate, which is converted to 5-fluorouracil (5-FU) selectively in tumours through a cascade of three enzymes. The present study investigated tissue localisation of the three enzymes in humans, which was helpful for us to design the compound. Carboxylesterase was almost exclusively located in the liver and hepatoma, but not in other tumours and normal tissue adjacent to the tumours. Cytidine (Cyd) deaminase was located in high concentrations in the liver and various types of solid tumours. Finally, thymidine phosphorylase (dThdPase) was also more concentrated in various types of tumour tissues than in normal tissues. These unique tissue localisation patterns enabled us to design capecitabine. Oral capecitabine would pass intact through the intestinal tract, but would be converted first by carboxylesterase to 5'-deoxy-5-fluorocytidine (5'-dFCyd) in the liver, then by Cyd deaminase to 5'-deoxy-5-fluorouridine (5'-dFUrd) in the liver and tumour tissues and finally by dThdPase to 5-FU in tumours. In cultures of human cancer cell lines, the highest level of cytotoxicity was shown by 5-FU itself, followed by 5'-dFUrd. Capecitabine and 5'-dFCyd had weak cytotoxic activity only at high concentrations. The cytotoxicity of the intermediate metabolites 5'-dFCyd and 5'-dFCyd was suppressed by inhibitors of Cyd deaminase and dThdPase, respectively, indicating that these metabolites become effective only after their conversion to 5-FU. Capecitabine, which is finally converted to 5-FU by dThdPase in tumours, should be much safer and more effective than 5-FU, and this was indeed the case in the HCT116 human colon cancer and the MX-1 breast cancer xenograft models.

Characterization and localization of thromboxane A2 receptor in human and guinea-pig nasal mucosa using radiolabelled (+)-S-145

1. TxA2 receptor (TP-receptor) antagonists such as S-1452 and Bay u 3405 have been shown to be effective in alleviating nasal blockage in patients with allergic rhinitis as well as guinea-pig allergic rhinitis models. The present study was conducted to examine the existence and localization of the TP-receptor in human and guinea-pig nasal mucosa by in vitro receptor binding autoradiography using radiolabelled (+)-S-145, which is a potent and specific TP-receptor antagonist with an extremely slow dissociation rate. 2. We ascertained the binding specificity of [3H]-(+ )-S-145 in human and guinea-pig platelet membranes by comparing the ability of four TP-receptor ligands of U-46619, (+)-S-145, I-(+)-S-145 and Bay u 3405 to displace the specific binding of [3H]-(+)-S-145 and [3H]-U-46619. The rank order of potency (Ki) for the displacement was correlated highly with that determined from [3H]-U-46619 binding to the same preparations. 3. Quantitative autoradiography using a radioluminographic imaging plate system, in which the radioactivity of [3H]-(+)-S-145 is expressed as photostimulated luminescence (PSL) per area (mm2), revealed that specific binding of [3H]-(+)-S-145 to human and guinea-pig nasal mucosa was saturable. Scatchard analysis showed about three fold higher affinity and two fold greater maximal binding to the nasal mucosa of humans than that of guinea-pigs: the KD and Bmax values in human mucosa were 2.82+/-0.35 nM and 6.47+/-0.33 PSL mm(-2) and those in guinea-pig mucosa were 8.23+/-1.93 nM and 3.37+/-0.66 PSL mm(-2), respectively. 4. Specific [3H]-(+)-S-145 binding to cryostat sections of human and guinea-pig nasal mucosa was displaced by another TP-receptor antagonist, Bay u 3405, and a TP-receptor agonist, U-46619. The order of potency (Ki value: nM) was (+)-S-145 (2.5) > Bay u 3405 (15.4) > > U-46619 (359.6) in human nasal mucosa and (+)-S-145 (22.8) > U-46619 (49.8) approximately Bay u 3405 (62.1) in guinea-pig nasal mucosa. These rank orders showed rather good correlation with those obtained for the respective platelet membranes. 5. Autoradiographs of human nasal mucosa demonstrated that specific [125I]-(+)-S-145 binding sites mainly exist on the smooth muscle layers of venous sinusoids and arterioles in the lamina propria, with few or no binding sites in the epithelium and nasal gland. 6. We concluded that radiolabelled (+)-S-145 can be used as a TP-receptor ligand for autoradiographic study, and that the TP-receptor is exclusively located on smooth muscle layers of venous sinusoids and arterioles in the nasal mucosa. The potent vasoconstrictive activity of TxA2 may cause reduction of local blood flow followed by mucosal oedema probably through mechanisms of vascular injury such as ischaemia-reperfusion.

Genomic organization of Drosophila poly(ADP-ribose) polymerase and distribution of its mRNA during development

Poly(ADP-ribosyl)ation of proteins catalyzed by poly(ADP-ribose) polymerase (PARP; EC 2.4.2.30) modulates several biological activities. However, little is known about the role of PARP in developmental process. Here we report the organization of the Drosophila PARP gene and the expression patterns during Drosophila development. The Drosophila PARP gene was a single copy gene mapped at 81F and composed of six exons. Organization of exons corresponds to the functional domains of PARP. The DNA-binding domain was encoded by exons 1, 2, 3, and 4. The auto-modification domain was encoded by exon 5, and the catalytic domain was in exon 6. The promoter region of the PARP gene contained putative TATA box and CCAAT box unlike human PARP. Expression of the PARP gene was at high levels in embryos at 0-6 h after egg laying and gradually decreased until 8 h. PARP mRNA increased again at 8-12 h and was observed in pupae and adult flies but not in larvae. In situ mRNA hybridization of embryos revealed large amount of PARP mRNA observed homogeneously except the pole cells at the early stage of embryos, possibly due to presence of the maternal mRNA for PARP, and decreased gradually until the stage 12 in which stage PARP mRNA localized in anal plates. At late stage of embryogenesis PARP mRNA was localized in cells along the central nervous system.

Identification of a major PAF acetylhydrolase in human serum/plasma as a 43 kDa glycoprotein containing about 9 kDa asparagine-conjugated sugar chain(s)

Platelet-activating factor (PAF) acetylhydrolase from human serum/plasma was identified on a polyvinylidene difluoride (PVDF) membrane by electroblotting proteins separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The enzyme activity was detected in the 43 kDa region on the membrane as a decrease in the beta-radioluminescence of [3H]acetyl-PAF or by the convenient method for determining PAF acetylhydrolase activity (the TCA precipitation method). The enzyme activity on treatment with N-glycosidase F shifted to the 34 kDa region on the PVDF membrane. On the other hand, only one band was observed, corresponding to a molecular mass of 53 kDa, on analysis by SDS-PAGE with silver staining. Treatment of the 53 kDa protein with N-glycosidase F changed its molecular mass to 43 kDa (protein A). The NH2-terminal 32 amino acid sequence of protein A completely corresponds to that of the heterogenous enzyme with 54 amino acids deleted from the NH2 terminus reported by Tjoelker et al. (Nature 374, 549-553, 1995). Even after trypsin treatment of the N-glycosidase F-digested enzyme, its PAF-AH activity remained in the 34 kDa region, but the contaminating protein A disappeared, on the PVDF membrane. In addition, the majority of serum PAF-AH was retained on a Sambucus sieboldiana agglutinin (SSA)-agarose column and was eluted with the hapten sugar, lactose. These results indicate that PAF acetylhydrolase consisting of a 34 kDa protein and about 9 kDa asparagine-conjugated sugar chain(s) is a major enzyme in human serum/plasma.

Transmission of human T-cell leukemia virus type 1 to mice

Human T-cell leukemia virus type 1 (HTLV-1) is associated with adult T-cell leukemia/lymphoma, HTLV-1-associated myelopathy/tropical spastic paraparesis, and other diseases. For prevention of the transmission of HTLV-1 and manifestation of these diseases, a small-animal model, especially a mouse model, would be useful. We injected HTLV-1-producing T cells (MT-2) intraperitoneally into neonatal C3H/HeJ mice. While the antibody against HTLV-1 antigens was not detectable in C3H/HeJ mice, HTLV-1 provirus was frequently detected in the spleen, lymph nodes, and thymus by PCR. HTLV-1 provirus was present at the level of 0 to 30 molecules in 10(5) spleen cells at the age of 15 weeks. In addition, a 59-bp flanking sequence of the HTLV-1 integration site was amplified from the spleen DNA by linker-mediated PCR and was confirmed to be derived from the mouse genome. HTLV-1 provirus was found in the T-cell fraction of the mouse spleen. These results indicate that mice can be infected by HTLV-1 and could serve as an animal model for the study of HTLV-1 infection and its pathogenesis in vivo.

The antiproliferative activity of DMDC is modulated by inhibition of cytidine deaminase

We showed that the efficacy of the new 2'-deoxycytidine (2'-dCyd) analogue antimetabolite 2'-deoxy-2'-methylidenecytidine (DMDC) correlates well with tumor levels of cytidine (Cyd) deaminase in human cancer xenograft models. DMDC was highly effective in tumors with higher levels of Cyd deaminase, whereas lower levels yielded only slight activity. In contrast, gemcitabine (2',2'-difluorodeoxycytidine), which has action mechanisms similar to those of DMDC, is only slightly active in tumors with higher levels of the enzyme. In the present study, we investigated the roles of Cyd deaminase in the antitumor activity of the two 2'-dCyd antimetabolites in 13 human cancer cell lines. Tetrahydrouridine, an inhibitor of Cyd deaminase, reduced the antiproliferative activity of DMDC (P = 0.0015). Furthermore, tumor cells transfected with the gene of human Cyd deaminase become more susceptible to DMDC both in vitro and in vivo. These results indicate that Cyd deaminase is indeed essential for the activity of DMDC. In contrast, the antiproliferative activity of gemcitabine was increased to some extent by tetrahydrouridine (P = 0.0277), particularly in tumor cell lines with higher levels of Cyd deaminase. This suggests that higher levels of Cyd deaminase may inactivate gemcitabine. Among nucleosides and deoxynucleosides tested, only dCyd, a natural substrate of both Cyd deaminase and dCyd kinase, suppressed the antiproliferative activity of DMDC by up to 150-fold. Because the Vmax/Km of DMDC for dCyd kinase was 8-fold lower than that for dCyd, the activation of DMDC to DMDC monophosphate (DMDCMP) by dCyd kinase might be competitively inhibited by dCyd. In addition, the dCyd concentrations in human cancer xenografts were inversely correlated with levels of Cyd deaminase activity. It is therefore suggested that higher levels of Cyd deaminase reduce the intrinsic cellular concentrations of dCyd in tumors, resulting in efficient activation of DMDC to DMDCMP by dCyd kinase. These results indicate that the efficacy of DMDC may be predicted by measuring the activity of Cyd deaminase in tumor tissues before treatment starts and that DMDC may be exploited in a new treatment modality: tumor enzyme-driven cancer chemotherapy.

PARP cleavage in the apoptotic pathway in S2 cells from Drosophila melanogaster

Caspase activities and two cDNA sequences have been identified in Drosophila melanogaster. To study the molecular events following the activation of the apoptotic pathway in D. melanogaster, S2 cells were treated with etoposide and the timing of the apoptotic events, such as caspase activation, mitochondrial pore opening, and loss of membrane asymmetry, was determined. Poly(ADP-ribose) polymerase (PARP) is known to be cleaved in the early phase of apoptosis in vertebrate systems. Little is known about the involvement of PARP cleavage in apoptosis in invertebrates. If PARP inactivation is a general event, this could mean that DNA repair enzymes need to be cleaved for the death pathway to be completed. We have found that in etoposide-treated cells, PARP protein is processed, but the nature of the cleavage is not known. Further experiments must be conducted and the peptide fragments must be sequenced to relate protease activities with PARP cleavage.