Arl4c expression in colorectal and lung cancers promotes tumorigenesis and may represent a novel therapeutic target

We recently demonstrated that expression of ADP-ribosylation factor (ARF)-like 4c (Arl4c) induced by a combination of Wnt/β-catenin and epidermal growth factor/Ras signaling in normal epithelial cells grown in three-dimensional culture promotes cellular migration and proliferation, resulting in formation of tube-like structures, suggesting the involvement of Arl4c in epithelial morphogenesis. It is conceivable that there could be a common mechanism between epithelial morphogenesis and carcinogenesis. Therefore the current study was conducted to investigate whether Arl4c might be involved in tumorigenesis. Immunohistochemical analyses of tissue specimens obtained from colorectal and lung cancer patients revealed that Arl4c was not observed in non-tumor regions but was strongly expressed at high frequencies in tumor lesions. Inhibition of Wnt/β-catenin or Ras/mitogen-activated protein kinase signaling reduced Arl4c mRNA levels in HCT116 colorectal cancer cells and A549 lung cancer cells. Knockdown of Arl4c inhibited Rac activity and also prevented nuclear localization of yes-associated protein (YAP)/transcriptional co-activator with PDZ-binding motif (TAZ) in these cancer cells. Arl4c-depleted cancer cells consistently showed decreased migration, invasion and proliferation capabilities both in vitro and in vivo. Furthermore, direct injection of Arl4c small interfering RNA (siRNA) into HCT116 cell-derived tumors (in vivo treatment with siRNA) inhibited tumor growth in immunodeficient mice. These results suggest that Arl4c is involved in tumorigenesis and might represent a novel therapeutic target for suppressing proliferation and invasion of colorectal and lung cancer cells.

[Simultaneous resection of pulmomary metastasis of colon cancer and primary lung cancer]

A 70-year-old woman was admitted with a complaint of weight loss and an abnormal shadow on the chest X-ray. On palpation, the unmobilized mass, measuring 5 cm, was located in the left lower abdomen. The barium-enema examination showed the filling defect of the sigmoid colon. Chest computed tomography (CT) showed a tumor, measuring 20 x 20 mm, located in the right upper lobe (S3) and a nodule, measuring 3 mm, located in the right lower lobe (S8). At first, we performed sigmoidectomy (D 3) for the colon cancer. Next, performed right upper lobectomy and a partial resection of the right lower lobe. Histopathologically, the one is a primary lung cancer, the other is a metastatic lung cancer. With an increase in colorectal and lung cancer, similar cases as ours seem to increase in number. When we treat multiple lung nodules with malignancy of other organs, we should consider 3 types of cases, 1) only primary, 2) primary and metastatic, 3) only metastatic.

Methyl 2-(methylthio)benzoate: the unique sulfur-containing sex pheromone of Phyllophaga crinita

The female-produced sex pheromone of Phyllophaga crinita (Burmeister) (Coleoptera: Scarabaeidae: Melolonthinae; the adult has no common name) is identified as methyl 2-(methylthio)benzoate. This is the first identification of a sulfur-containing, long-distance, female-produced sex attractant from any insect taxa. The root-feeding larvae of this species are serious pests in many crops in Texas and Mexico. In field tests, many P. crinita males were captured in traps baited with the authentic compound. Interestingly, a heteroatom analog, methyl 2-methoxybenzoate, also captured P. crinita males, but only at a dose 10,000 times higher than the lowest tested dose of the authentic pheromone.

Exon 3 of tyrosine hydroxylase gene: lack of association with Japanese schizophrenic patients

Tyrosine hydroxylase (TH) is the rate-limiting enzyme in dopamine (DA) biosynthesis. Exon 3 of the human TH gene encodes the sequence from Ser31 to Glu104 of type 1 enzyme, which contains the critical parts for regulation of the catalytic activity. The amino acid residues Gly36-Arg37-Arg38 were identified as a key sequence for DA to exert its inhibitory effect on catalytic activity. Therefore, we screened the nucleotide sequences of exon 3 from 201 Japanese patients with schizophrenia to explain the elevation in the synaptic or presynaptic DA concentrations in the schizophrenic brain, based on the hypothesis that any mutation changing the amino acid sequence Gly36-Arg37-Arg38 would result in the elevation of DA synthesis, due to a reduced inhibitory effect of DA on the catalytic activity. However, no mutated sequences of exon 3 and both exon-intron boundaries were detected in any of the patients examined. Polymorphisms generating Val81 and Met81 were compared of the distributions of genotype and allele between the patients and 175 Japanese healthy controls, which did not suggest an association between the polymorphism and schizophrenia. These results indicate that exon 3 of the human TH gene lacks association with schizophrenia in Japanese patients.

Structure-activity relationship of orally potent tripeptide-based HIV protease inhibitors containing hydroxymethylcarbonyl isostere

We designed and synthesized a new class of peptidomimetic human immunodeficiency virus protease inhibitors containing a unique unnatural amino acid, allophenylnorstatine [Apns; (2S,3S)-3-amino-2-hydroxy-4-phenylbutyric acid], with a hydroxymethylcarbonyl isostere as the active moiety. From a structure-activity relationship study of HIV-1 protease inhibition, enzyme selectivity for other aspartyl proteases, the antiviral activity and pharmacokinetics in rats, 24c (KNI-227) and 24d (KNI-272, our first clinical candidate) were found to be selective and orally potent HIV protease inhibitors. Moreover, an improvement of the pharmacokinetic features of KNI-272 provided two long-lasting and highly bioavailable compounds (24g: JE-2178, 24h: JE-2179).

The Escherichia coli pldC gene encoding lysophospholipase L(1) is identical to the apeA and tesA genes encoding protease I and thioesterase I, respectively

We deduced the amino acid sequence of Escherichia coli lysophospholipase L(1) by determining the nucleotide sequence of the pldC gene encoding this enzyme. The translated protein was found to contain 208 amino acid residues with a hydrophobic leader sequence of 26 amino acid residues. The molecular weight of the purified enzyme (20,500) was in good agreement with the predicted size (20,399) of the processed protein. A search involving a data bank showed that the nucleotide sequence of the pldC gene was identical to those of the apeA and tesA genes encoding protease I and thioesterase I, respectively. Consistent with the identity of the pldC gene with these two genes, the enzyme purified from E. coli overexpressing the pldC gene showed both protease I and thioesterase I activities.

Induction of terminal differentiation and apoptosis in human colonic carcinoma cells by brefeldin A, a drug affecting ganglioside biosynthesis

An appreciable increase in G(M3) with a concomitant decrease in some neolacto-series gangliosides was observed during differentiation of human colonic carcinoma HCT 116 cells induced by a differentiating agent. When the cells were treated with brefeldin A (BFA), a striking increase in de novo biosynthesis of G(M3) and a decrease in biosynthesis of neolactoseries gangliosides were observed after 6 h. Clear morphological changes to differentiated epithelial cells and an arrest of cells in the G0/G1 phase of the cell cycle were observed after 1 day of treatment. Then the cells were led to apoptosis. This activity was not affected by forskolin, which antagonizes the effects of BFA on protein transport and the Golgi apparatus. These results suggest that the differentiation-inducing activity of BFA might be due to its modulatory effect on ganglioside biosynthesis, and that a specific change in ganglioside pattern is an essential prerequisite for induction of differentiation, providing a novel target for differentiation therapy of cancer.

Structure-activity relationship of small-sized HIV protease inhibitors containing allophenylnorstatine

We designed and synthesized a new class of peptidomimetic human immunodeficiency virus (HIV) protease inhibitors containing a unique unnatural amino acid, allophenylnorstatine [Apns; (2S, 3S)-3-amino-2-hydroxy-4-phenylbutyric acid], with a hydroxymethylcarbonyl (HMC) isostere as the active moiety. A systematic evaluation of structure-activity relationships for HIV protease inhibition, anti-HIV activities, and pharmacokinetic profiles has led to the delineation of a set of structural charateristics that appear to afford an orally available HIV protease inhibitor. Optimum structures, exemplified by 21f (JE-2147), incorporated 3-hydroxy-2-methylbenzoyl groups as the P2 ligand, (R)-5,5-dimethyl-1,3-thiazolidine-4-carbonyl (Dmt) residue at the P1' site, and 2-methylbenzylcarboxamide group as the P2' ligand. The present study demonstrated that JE-2147 has potent antiviral activities in vitro and exhibits good oral bioavailability and plasma pharmacokinetic profiles in two species of laboratory animals.

Changes in composition of newly synthesized sphingolipids of HeLa cells during the cell cycle -- suppression of sphingomyelin and higher-glycosphingolipid synthesis and accumulation of ceramide and glucosylceramide in mitotic cells

Sphingolipid biosynthesis in synchronized HeLa cells was studied by pulse labeling with [14C]Ser or [14C]Gal and a simple TLC method. The major HeLa cell sphingolipids are ceramide (Cer), sphingomyelin, glucosylceramide (GlcCer), lactosylceramide (LacCer), globotriaosylceramide (Gb3Cer), N-acetylneuraminosylgangl iotriaosylceramide (GM2) and sialylparagloboside (G[M1-GlcNAc]). The sphingolipid biosynthetic profiles of HeLa cells in the G1, G1/S boundary, S and G2 phases were similar, but significant changes occurred during M phase, when incorporation of radioactivity into sphingomyelin, Gb3Cer and a mixture of GM2 and G(M1-GlcNAc) decreased, and those of Cer and GlcCer increased. These data indicate that transfer of phosphocholine and galactose to Cer and GlcCer, respectively, decreased in mitotic cells, resulting in accumulation of Cer and GlcCer. Analysis of LacCer synthase activity revealed that GlcCer accumulation was not due to reduced activity of this enzyme. The results suggest that Cer and GlcCer accumulation in mitotic cells resulted from suppression of sphingomyelin and LacCer synthesis, probably caused by vesiculation of membranous organelles, such as the endoplasmic reticulum and Golgi apparatus.

Activated mast cells release extracellular type platelet-activating factor acetylhydrolase that contributes to autocrine inactivation of platelet-activating factor

IgE-dependent and -independent activation of mouse bone marrow-derived mast cells (BMMC) elicited rapid and transient production of platelet-activating factor (PAF), which reached a maximal level by 2-5 min and was then degraded rapidly, returning to base-line levels by 10-20 min. Inactivation of PAF was preceded by the release of PAF acetylhydrolase (PAF-AH) activity, which reached a plateau by 3-5 min and paralleled the release of beta-hexosaminidase, a marker of mast cell exocytosis. Immunochemical and molecular biological studies revealed that the PAF-AH released from activated mast cells was identical to the plasma-type isoform. In support of the autocrine action of exocytosed PAF-AH, adding exogenous recombinant plasma-type PAF-AH markedly reduced PAF accumulation in activated BMMC. Furthermore, culture of BMMC with a combination of c-kit ligand, interleukin-1beta and interleukin-10 for > 24 h led to an increase in plasma-type PAF-AH expression, accompanied by a reduction in stimulus-initiated PAF production. Collectively, these results suggest that plasma-type PAF-AH released from activated mast cells sequesters proinflammatory PAF produced by these cells, thereby revealing an intriguing anti-inflammatory aspect of mast cells.

Separation of 18 6-aminoquinolyl-carbamyl-amino acids by ion-pair chromatography

Eighteen 6-aminoquinolyl-carbamyl (AQC)-amino acids were separated by ion-pair chromatography, using tetrabutylammonium (TBA) as a counterion. Optimum separation was obtained on a C8 reverse-phase column using gradient elution with two mobile phases, A (5 mM TBA, 75 mM ammonium acetate, pH 7.5) and B (80% acetonitrile). The AQC-amino acids were detected by fluorescence with excitation at 250 nm and emission at 395 nm, and the analysis time was 65 min. The response factors of individual AQC-amino acids to AQC-phenylalanine ranged from 0.42 to 1.08 (except for tryptophan at 0.01), with an average of 0.8. Detection limits by fluorescence ranged from 11.8 fmol (threonine) to 51.7 fmol (methionine), except for tryptophan (1.8 pmol).

[Decision-making style among hemodialysis patients]

The purpose of this descriptive study was to identify the decision-making style among the dialysis patients. Subjects were a Convenience sample of hemodialysis patients who agreed to participate this study. The data was collected through semi-structured interviews. The interviews were recorded on the tape and transcribed. Decision-making episodes were picked and interpreted by searchers. Data was analyzed based on the Inductive Theory Approach.

RESULT

Subject were 21 patients from 4 hospitals. The mean age was 51.1 and the mean duration after they started the hemodialysis was 9.1 years. The 16 decision-making styles were identified: accept, unvacillate, resignation, compromise, perseverance, challenge, self-activation, groupie, crisis-avoidance, withdrawal, prudent, reserve, escape, refusal, dogmatic, and entrust. These 16 decision-making styles were characterized by the reality oriented perception, the constructive regimes, the higher quality of social support. On the other hand, the passive decision-making styles were characterized by the distorted perception, the passive regimes, and the poor social support.

DISCUSSION

The reality orientation, energy, openness, values system were discussed as key factors which determined the decision-making style among hemodialysis patients. The nursing approach supporting the patients to make their decision were discussed.

[Components of decision-making among hemodialysis patients]

The purpose of this descriptive study was to identify the components of decision-making among the dialysis patients. Subjects were a Convenience sample of hemodialysis patients who agreed to participate this study. The data was collected through semi-structured interviews was recorded on the tape and transcribed. Decision-making episodes were picked and interpreted by researchers. Data was analysed based on the Grounded Theory Approach.

RESULT

Subject were 21 patients from 4 hospitals. The mean age was 51.1 and the mean duration after the hemodialysis was 9.1 years. The number of episode of decision-making were 136. Six components of decision-making were extracted such as <goal> <recognition of situation> <recognition of self> <choice> <planning> <evaluation>. The subject were making decision by examining and judging the situation and oneself, and then setting the goal. They were selecting situation and themselves. After all, the outcomes of decision-making were evaluating. Seven type of decision-making, erection type, reality-oriented type, elaborate type, dogmatic type, passive type, chance type, resistant type were extracted.

DISCUSSION

The factors which were related to the quality of decision-making were discussed such as the ability to examine the reality and control own wishes and needs, and the commitment for the decision-making. The nursing approach to facilitate the patients to make the decision were mentioned.

Cloning, expression and characterization of plasma platelet-activating factor-acetylhydrolase from guinea pig

In a previous study, we purified PAF-acetylhydrolase, which converts PAF to an inactive metabolite, lysoPAF, from peritoneal fluid of guinea pigs subjected to experimental endotoxin shock and found that this purified enzyme had similar biochemical properties to the plasma enzyme [Karasawa, K., Yato, M., Setaka, M., and Nojima, S. (1994) J. Biochem. 116, 374-379]. In this study, we isolated a homogeneous enzyme preparation from guinea pig plasma using a similar procedure. The molecular mass of this purified enzyme, as determined by SDS-PAGE was 58-63 kDa, larger than that (43 kDa) of the human enzyme. To elucidate the molecular structure of this enzyme and clarify its relationships with PAF-acetylhydrolases of other species, we isolated and sequenced a cDNA encoding this enzyme. Its cDNA contains an open reading frame encoding 436 amino acids and its predicted molecular mass (49 kDa) is lower than that of the native enzyme, suggesting that guinea pig plasma PAF-acetylhydrolase, unlike the human enzyme, is modified post-translationally, perhaps by glycosylation.

A distribution study of 11C platelet-activating factor (PAF) analogs in normal and tumor-bearing mice

As a preliminary study to image platelet-activating factor (PAF) receptors in vivo, comparative study of biodistribution between 1-O-hexadecy1-2-O-N, N-dimethylcarbamoyl-sn-glycero-3-phosphocholine [choline-methyl-11C](L-[11C]dimethylcarbamoyl-PAF) and nonspecific PAF analog, 3-O-hexadecyl-2-O-N,N-dimethylcarbamoyl-sn-glycero-1-phosphocholine [choline-methyl-11C](D-[11C]-dimethylcarbamoyl-PAF) was carried out in both normal and tumor-bearing mice. Higher accumulation of L-[11C]dimethylcarbamoyl-PAF than D-[11C]dimethylcarbamoyl-PAF was observed in normal mice spleen. The co-administration of PAF antagonists dose-dependently reduced the radioactivity level of the L-isomer only in the spleen. In mice bearing Ehrlich tumors and Sarcoma 180, more L-than the D-[11C]-isomer was accumulated in the tumor and spleen. We found that specific accumulation sites for L-[11C]dimethylcarbamoyl-PAF exist in the spleen and tumors than in other tissues. Moreover, the comparison of accumulation between L- and D-[11C] dimethylcarbamoyl-PAF would be a useful procedure for estimation of PAF receptors in vivo.

[Characteristics of psychosocial nursing care--the dimensions of psychosocial nursing care to promote empowerment among patients]

Nurses provide the psychosocial nursing care to promote the patients' empowerment. In spite of recognizing the importance of psychosocial nursing. The research reported here is part of a large study designed to explore the psychosocial nursing intervention strategies. This part of the study is focused on characteristics of psychosocial nursing care as identified by nurses. Research design was descriptive and qualitative. Subjects were a convenient sample of nurses who have more than 5 years experience and agreed to participate in this research. Data was collected through semistructured interviews. Data was recorded on a tape and transcribed, then analyzed based on Grounded Theory Approach.

SUBJECTS

The number of subjects consisted of 39 nurses. The average age and duration of clinical experience was 36.6 years old and 12.6 years.

RESULT

Sixteen of the characteristics of psychosocial nursing to promote the empowerment among the patients were identified; 1) respect the patients' decision making, 2) clinical judgment from multiple perspectives, 3) predictability, 4) flexibility, 5) classification of the patients by comparison, 6) monitoring, 7) relief from reality, 8) relief from pain and suffering, 9) enhancement of the patients' ego strength, 10) nurture of hope, 11) support individualized daily living styles, 12) encouragement of the patients'own problem solving abilities, 13) respect of individuality, 14) self-utilization, 15) self-control based on professional identity, 16) utilization of team power.

DISCUSSION

Nurses choose from the sixteen dimensions of psychosocial nursing and organizing them in order to stabilizing the patients' conditions.

Clear differences in ceramide metabolism between glycosphingolipids and sphingomyelin in a human promyelocytic leukemia cell line HL-60 stimulated by a differentiation inducer

Although the ceramide components of both glycosphingolipids (GSLs) and sphingomyelin (SM) in HL-60 cells were identical, the molecular species of the ceramides preferentially used in biosynthesis were quite different in GSLs and SM. When HL-60 cells were stimulated to differentiate into macrophage-like cells by phorbol ester after their sphingolipids had been metabolically labeled with L-[3-14C]serine to saturation point, marked changes in the radioactivities of the ceramide residues were observed in GSLs, showing the activation of a biosynthetic pathway of ganglioside GM3. No significant changes were, however, observed in the ceramide residues of SM. These results indicate that it is necessary to consider the overall metabolism of ceramides, including their origin, when investigating the functions of ceramides in signal transduction systems.

Platelet-activating factor (PAF) and the formation of chronic subdural haematoma. Measurement of plasma PAF levels and anti-PAF immunoglobulin titers

In order to estimate the contribution of platelet-activating factor (PAF) to the formation of chronic subdural haematomas (CSH), we measured plasma PAF and anti-PAF antibody levels in head-injured patients with and without CSH and normal volunteers. Plasma PAF and anti-PAF IgG levels were higher in patients with CSH than in patients without CSH or in normal volunteers. Furthermore, plasma PAF and anti-PAF IgG levels increased in a time-dependent manner over the first 35 days following head injury. These data suggest that PAF may be involved in the generation of CSH.

Accumulation of platelet-activating factor acetylhydrolase in the peritoneal cavity of guinea pig after endotoxin shock

We examined the production of PAF, a mediator of shock, and LysoPAF, an inactive metabolite of PAF, in the guinea pig peritoneal cavity after i.p. administration of Escherichia coli LPS. Within 1 h of LPS administration, the level of PAF in the peritoneal fluid increased from 4.9 to 37.2 pmol/animal and decreased to the control value thereafter. In contrast, the level of lysoPAF gradually rose from 63.5 to 268 pmol/animal for up to 6 h. The activity of acetylhydrolase, which converts PAF to lysoPAF, in the peritoneal cavity increased in parallel with the increase in the lysoPAF level. The enzyme was distinguishable from phospholipase A2, because p-bromophenacylbromide (p-BPB), Ca2+, and ethylenediaminetetraacetic acid (EDTA) did not affect its enzymatic activity. In addition, this acetylhydrolase revealed similar biochemical properties to that detected in plasma. Both acetylhydrolases were resistant to trypsin treatment and had the same apparent molecular weight, as shown by gel-filtration column chromatography. These results suggest that the acetylhydrolase, which accumulates in the peritoneal cavity, infiltrates from the plasma in response to LPS, and then participates in the exclusion of PAF during endotoxin shock.

Differences related to the production of arachidonic acid between collagen- and thrombin-stimulated human platelets

The effects of collagen and thrombin on the liberation of free arachidonic acid were investigated in human platelets by fluorometric high-performance liquid chromatography. Collagen induced a concentration-dependent increase in the extent of platelet aggregation, as well as an accumulation of arachidonic acid in human platelets. By contrast, thrombin effectively provoked a potent aggregation at relatively low concentration without any accumulation of free arachidonic acid, although the accumulation of arachidonic acid was detected at a high concentration of thrombin (> 0.1 U/ml) that induced full aggregation. The selective liberation of arachidonic acid was found in thrombin-stimulated platelets. Non-selective liberation of fatty acids occurred in platelets that had been stimulated with a high concentration of collagen (10 micrograms/ml), as well as in platelets stimulated with A23187. The net amount of free arachidonic acid in collagen-stimulated platelets was estimated by use of eicosatetraenoic acid (ETYA), which is an inhibitor of both cyclooxygenase and lipoxygenase. ETYA markedly potentiated the accumulation of free arachidonic acid in collagen-stimulated platelets without changing the amounts of other fatty acids in the cell.

Purification and characterization of platelet-activating factor acetylhydrolase from peritoneal fluid obtained from guinea pigs after endotoxin shock

Platelet-activating factor (1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine; PAF) acetyl-hydrolase is an enzyme that hydrolyzes the acetyl ester of PAF. We purified this enzyme, which accumulated in the peritoneal cavity during endotoxin shock, by ammonium sulfate precipitation, and sequential use of butyl-Toyopearl, heparin-Sepharose, Con A-Sepharose, chelating-Sepharose, and MonoQ column chromatographies. We identified a monomeric polypeptide with a molecular weight of approximately 63 kDa on SDS-PAGE. This molecular weight differs from those of previously described acetylhydrolases. The purified enzyme did not degrade phospholipids with a long chain fatty acyl group at the sn-2 position. In addition, the enzyme activity was not inhibited by either pBPB or quinacrine. Accordingly, this enzyme is distinct from phospholipase A2. In addition, this enzyme also hydrolyzed some oxidatively fragmented phospholipids with PAF-like biological activities such as 1-O-hexadecyl-2-glutaroyl-sn-glycero-3-phosphocholine and 1-O-hexadecyl-2-succinoyl-sn-glycero-3-phosphocholine.

Platelet-activating factor (PAF) and the development of chronic subdural haematoma

Platelet activating factor (PAF) content and PAF-acetylhydrolase (PAFAH) activity were measured in the plasma and haematoma of 34 chronic subdural haematoma (CSH) patients. The plasma PAF level in patients with CSH was higher than that in healthy controls. Although there was no correlation between the plasma PAF levels and the interval between the onset of symptoms and the day of sampling, namely, the interval after bleeding, the haematoma PAF level gradually decreased according to the interval after the onset of symptoms. There was no difference between plasma PAFAH activity in patients with CSH and that in healthy controls, and haematoma enzyme activity gradually increased correlated with the interval between the onset of symptoms and surgery. In addition, the localization of PAF in haematoma capsules was histochemically determined. PAF was solely localized to the peri-sinusoidal vessels in the outer membrane of haematoma capsules. Based on these biochemical and histochemical studies, we speculated that PAF may play a role in the development of chronic subdural haematomas.

[The relationship between the family system and the family coping among families with a chronically ill child]

The purposes of this study were to identify the family coping strategies among families with chronically ill children and to explore the relationship between the family system (variables), the family burden and the family coping. One hundred fifty-two families with chronically ill children were studied. The Japanese version of Family Adaptability and Cohesion Evaluation Scales II and the Family Coping Behavior Inventory II were used. The result were 1) the family cohesion and adaptability in families with a chronically ill child tended to be lower than normal families; 2) the integration coping pattern was positively related with family cohesion and the family burden; 3) the problem solving coping pattern was positively related with the family burden; 4) the normalization coping pattern was negatively related with the family burden and positively related with the family cohesion; 5) the crisis response coping pattern was positively related with the family burden and negatively related with the family cohesion.

Immunofluorescent localization of platelet-activating factor (PAF) in the rat

An immunofluorescent staining method for detecting platelet-activating factor (PAF) is described. This method employs a polyclonal anti-PAF rabbit antibody. When rat brain, heart, lung, liver or kidney tissue was stained using this method, the heart, lung and kidney exhibited PAF-specific staining. Analysis of the amount of PAF in different organs, either by immunofluorescence or by bioassay, showed that kidney tissue contains the greatest amount of PAF.

Platelet-activating factor and cerebral vasospasm following subarachnoid hemorrhage

This study examines whether platelet-activating factor (PAF) is involved in the occurrence of vasospasm after subarachnoid hemorrhage (SAH). A vasospasm model was produced in rabbits, with animals in six experimental groups receiving two subarachnoid injections of autologous arterial blood with the addition of one of the following; saline (Control Group 1), 25% dimethyl sulfoxide (Control Group 2), PAF (1, 2.5, 5, or 10 micrograms), CV6209 (10 or 100 micrograms), BN52021 (10 or 100 micrograms), or anti-PAF immunoglobulin G (IgG, 50 or 500 micrograms). No significant differences were detected between Control Groups 1 and 2 with regard to neurological deterioration and basilar artery constriction after SAH was induced. Administration of PAF together with autologous blood aggravated neurological deficits in a dose-dependent manner (r = 0.724, p < 0.001) and produced basilar artery constriction at two doses each of 2.5 micrograms (p < 0.05), 5 micrograms (p < 0.01), and 10 micrograms (p < 0.01). Neurological deterioration was prevented in rabbits receiving an intracisternal administration of either PAF antagonist CV6209 or BN52021 or anti-PAF IgG (p < 0.01 at a total dose of 20 micrograms and p < 0.05 at a total dose of 200 micrograms CV6209, p < 0.01 at total doses of 20 and 200 micrograms BN52021, and p < 0.01 at total doses of 100 and 1000 micrograms anti-PAF IgG). A reduction in basilar artery constriction was achieved by the injection of anti-PAF IgG (p < 0.05 at total doses of 100 and 1000 micrograms). Histological examination at autopsy on Days 14 to 21 showed mainly ischemic changes in the brain, including selective neuronal necrosis and cerebral infarction. The control and PAF groups showed marked ischemic changes. On the other hand, no ischemic changes were noted in the anti-PAF IgG group, and only 9% of animals in the CV6209 group and 25% in the BN52021 group demonstrated selective neuronal necrosis or infarction. This study thus provides evidence to support the role of PAF in the pathogenesis of vasospasm after SAH.

Possible influence of lysophospholipase on the production of 1-acyl-2-acetylglycerophosphocholine in macrophages

The rate of production of 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine (PAF) and 1-acyl-2-acetyl-sn-glycero-3-phosphocholine (acylPAF) was measured in macrophages following the incorporation of [3H]acetate. Upon activation by A23187, guinea pig alveolar macrophages incorporated [3H]acetate into PAF, but a little radioactivity was found in acylPAF. However, labeling of acylPAF and PAF with [3H]acetate was greatly enhanced in A23187-stimulated alveolar macrophages that had been pretreated with phenylmethanesulphonyl fluoride (PMSF). [3H]PAF was predominantly converted to 1-[3H]alkyl-2-acyl glycerophosphocholine, but [14C]acylPAF rapidly hydrolyzed to 14C-labeled free fatty acid by the incubation with lysates prepared from macrophages. The deacetylation of [14C]acylPAF and [3H]PAF by acetylhydrolase and also the hydrolysis of [14C]lysoPC by lysophospholipase were strongly inhibited in macrophages that had been pretreated with PMSF, while PMSF failed to inhibit the activities of acetyltransferase and acyltransferase. The relative proportions of PAF and acylPAF were quite different in different types of cells. In contrast to alveolar macrophages, peritoneal macrophages, neutrophils and spleen cells from guinea pigs incorporated 2-4 times more [3H]acetate into acylPAF than into PAF. The presence of high levels of acylPAF in peritoneal macrophages was confirmed by GLC-MS analysis. The activities of lysophospholipase, acetylhydrolase and acetyltransferase were measured in alveolar and peritoneal macrophages to determine whether the preferential formation of acylPAF as compared to PAF in peritoneal macrophages was due to differences in these activities between alveolar and peritoneal macrophages. The activity of acetylhydrolase of peritoneal macrophages was almost the same as that in alveolar macrophages. The activity of acetyltransferase in peritoneal macrophages was about half of that in alveolar macrophages. However, the activity of lysophospholipase in peritoneal macrophages was one-sixth of that in alveolar macrophages. These results suggest that lysophospholipase is one of the primary factors involved in the control of the production of acylPAF in activated cells, and that it acts by modulating the availability of lysoPC for the synthesis of acylPAF. Furthermore, high levels of activity of lysophospholipase allow the preferential formation of PAF, via the rapid hydrolysis of lysoPC which would act as a competitive inhibitor of the incorporation of acetate into lysoPAF.

40-GHz bandwidth InGaAs/InAlAs multiple quantum well optical intensity modulator

High-speed waveguide InGaAs/InAIAs multiple quantum well (MQW) optical intensity modulators are demonstrated. To minimize the modulator capacitance, an undoped InAIAs cladding layer is added over the MQW core layer in the optical waveguide. In addition, polyimide is spin coated under the bonding pad. As a result, a very wide bandwidth in excess of 40 GHz is developed with a driving voltage of 6 V for a 10-dB extinction ratio and a linewidth broadening factor alpha of < 1.0 at an operating wavelength of 1.54 microm. The frequency response of the modulator is limited by the device capacitance and inductance.

Biological response of guinea pig peritoneal macrophages to platelet-activating factor

We investigated the effects of platelet-activating factor (PAF) on guinea pig peritoneal macrophages. Specific and high-affinity binding sites for PAF were detected on guinea pig peritoneal macrophages. Scatchard analysis of PAF binding revealed high affinity binding sites (7.9 x 10(4)/cell) with a dissociation constant of 2.3 x 10(-10) M. When treated with 10(-9)-10(-5) M PAF, guinea pig peritoneal macrophages released hydrogen peroxide into the medium in a time-dependent manner. The release reaction upon stimulation with 10(-5) M PAF reached a plateau within 30 min and the extent of release was twice as high as that when stimulated by N-formyl-L-methionyl-leucyl-L-phenylalanine (fMLP; 2 microM)-treated cells. Neither lysoPAF nor the PAF enantiomer was effective. PAF-induced H2O2 release was inhibited specifically by PAF antagonists, suggesting that PAF activated macrophages through binding to specific sites. Lysosomal enzyme (N-acetyl-beta-D-glucosaminidase) was released from guinea pig peritoneal macrophages upon treatment with 10(-5) M PAF for 60 min. Guinea pig peritoneal macrophages were treated with PAF for 8 hr and the conditioned medium was examined for cytokines. The medium exhibited cytocidal activity against mouse fibroblast L929 cells [tumor necrosis factor (TNF) activity], and this activity was comparable to that detected after treatment of cells with the bacterial lipopolysaccharide (LPS). Furthermore, the same conditioned medium also showed colony-stimulating factor (CSF) activity. Generation of these cytokines was stereospecific. Our findings suggest that PAF is a unique macrophage activator that potentiates both respiratory burst/lysosomal enzyme release (early-phase response) and monokine production/glucose consumption (late-phase response).

Radioimmunoassay for platelet-activating factor

A radioimmunoassay (RIA) for measurement of platelet-activating factor (PAF) was developed. At a final antiserum dilution of 1:640, the lowest detection limit of PAF was 0.1 pmol (50 pg). The standard curve obtained was suitable for measurement of PAF in amounts ranging from 0.1 pmol to 30 pmol. The antiserum showed high specificity. Cross-reaction for lysoPAF, lysophosphatidylcholine and long-chain phosphatidylcholines was very low (less than 0.025%). 1-Palmitoyl-2-acetyl-sn-glycero-3-phosphocholine cross-reacted slightly (6.25%). PAF exogenously added to macrophage suspensions was quantitatively determined by RIA after solvent extraction and high-performance liquid chromatographic separation. RIA was also used to estimate PAF formation after stimulation of rabbit alveolar macrophages in suspension with calcium ionophore A23187.

Specific binding of antibodies to platelet-activating factor (PAF) as demonstrated by thin-layer chromatography/immunostaining

The specificity of rabbit antibodies produced by injection of 1-O-(15'-carboxypentadecyl)-2-N,N-dimethylcarbamoyl-sn-glycero-3- phosphocholine bovine serum albumin (BSA) conjugates was examined by a thin-layer chromatography (TLC/immunostaining method. Phosphatidylcholine (PC), lysophosphatidylcholine (lysoPC), lyso platelet-activating factor (lysoPAF), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), phosphatidylserine (PS), sphingomyelin (SM), phosphatidylinositol (PI), phosphatidic acid (PA) and cardiolipin (CL) were not immunostained. Among several synthetic PAF-related compounds, the antibodies only bound to PAF agonists which have the activity to induce washed rabbit platelet aggregation. The results suggest that the binding sites of the antibodies on the PAF molecule are the acetyl group at the sn-2 position and the choline moiety at the sn-3 position of glycerol, both of which are essential for exerting the biological function of PAF and for binding to the PAF receptors located on cellular membranes.