p53AIP1, a potential mediator of p53-dependent apoptosis, and its regulation by Ser-46-phosphorylated p53

Through direct cloning of p53 binding sequences from human genomic DNA, we have isolated a novel gene, designated p53AIP1 (p53-regulated Apoptosis-Inducing Protein 1), whose expression is inducible by wild-type p53. Ectopically expressed p53AIP1, which is localized within mitochondria, leads to apoptotic cell death through dissipation of mitochondrial A(psi)m. We have found that upon severe DNA damage, Ser-46 on p53 is phosphorylated and apoptosis is induced. In addition, substitution of Ser-46 inhibits the ability of p53 to induce apoptosis and selectively blocks expression of p53AIP1. Our results suggest that p53AIP1 is likely to play an important role in mediating p53-dependent apoptosis, and phosphorylation of Ser-46 regulates the transcriptional activation of this apoptosis-inducing gene.

Neonicotinoids: insecticides acting on insect nicotinic acetylcholine receptors

Imidacloprid is increasingly used worldwide as an insecticide. It is an agonist at nicotinic acetylcholine receptors (nAChRs) and shows selective toxicity for insects over vertebrates. Recent studies using binding assays, molecular biology and electrophysiology suggest that both alpha- and non-alpha-subunits of nAChRs contribute to interactions of these receptors with imidacloprid. Electrostatic interactions of the nitroimine group and bridgehead nitrogen in imidacloprid with particular nAChR amino acid residues are likely to have key roles in determining the selective toxicity of imidacloprid. Chemical calculation of atomic charges of the insecticide molecule and a site-directed mutagenesis study support this hypothesis.

Induction of cyclooxygenase 2 in gastric mucosal lesions and its inhibition by the specific antagonist delays healing in mice

BACKGROUND & AIMS

The role of two forms of cyclooxygenase (COX-1 and COX-2) in gastric mucosal lesions is not well understood. The regulation of both forms of COX and the effect of COX-2 on the repair process of gastric mucosal lesions in mice were investigated.

METHODS

Gastric mucosal erosions and ulcers were induced experimentally in mice. The level of COX messenger RNA (mRNA) was determined by reverse-transcription polymerase chain reaction. COX proteins were detected by Western blot analysis, and COX activity was determined in the presence or absence of NS-398, a specific COX-2 antagonist. The effects of long-term administration of NS-398 on gastric ulcers were examined.

RESULTS

COX-2 mRNA levels were not detected in control conditions but were high during the acute stages of gastric erosions and ulcers. COX-2 protein was detected 5 days after ulcer induction but not in control mice. Gastric ulceration was not associated with a change in COX-1 mRNA and protein levels. Administration of NS-398 to mice with ulcers at acute stages impaired the healing of ulcers.

CONCLUSIONS

High levels of COX-2 mRNA and protein during the acute stages of gastric mucosal lesions may be involved in the repair process of these lesions in mice.

Magnifying endoscopy combined with narrow band imaging system for early gastric cancer: correlation of vascular pattern with histopathology (including video)

BACKGROUND AND STUDY AIMS

The narrow band imaging (NBI) system consists of a sequential electronic endoscope system and a source of light equipped with new narrow band filters, yielding very clear images of microvessels on mucosal surfaces. The aim of this prospective study was to measure the correlation between the magnified images obtained with the NBI system and the histological findings, especially with regard to the vascular pattern. In addition, three-dimensional images of microvessels were reconstructed using a laser scanning microscope.

PATIENTS AND METHODS

Between July 2001 and August 2003, 165 patients with depressed-type early gastric cancer lesions were enrolled in the study. The lesions were carefully observed with magnification using the NBI system. The images, the pathological characteristics of the lesions, and three-dimensionally reconstructed images of the microvascular networks in biopsied specimens were carefully analyzed. The microvascular patterns were classified into three groups: A, fine network; B, corkscrew; and C, unclassified pattern. The endoscopic images were compared with the histological findings.

RESULTS

Of the three types of filter available for use with the NBI system, microvascular formation was best enhanced in B mode images produced using short wavelengths, which focus on the superficial mucosal layer. Among 109 cases of differentiated adenocarcinoma, the group A microvascular pattern was observed in 72 cases (66.1 %). Among 56 cases of undifferentiated adenocarcinoma, the group B pattern was observed in 48 cases (85.7 %; P = 0.0011) The microvascular structure observed using the NBI system corresponded with the superficial mucosal layer in the three-dimensional images obtained using laser scanning microscopy and the resected specimens.

CONCLUSIONS

Magnifying endoscopy performed in combination with the NBI system is not sufficient to replace conventional histology, but is capable of predicting the histological characteristics of gastric cancer lesions.

A novel gene family defined by human dihydropyrimidinase and three related proteins with differential tissue distribution

We have isolated cDNA clones encoding dihydropyrimidinase (DHPase) from human liver and its three homologues from human fetal brain. The deduced amino acid (aa) sequence of human DHPase showed 90% identity with that of rat DHPase, and the three homologues showed 57-59% aa identity with human DHPase, and 74-77% aa identity with each other. We tentatively termed these homologues human DHPase related protein (DRP)-1, DRP-2 and DRP-3. Human DRP-2 showed 98% aa identity with chicken CRMP-62 (collapsin response mediator protein of relative molecular mass of 62 kDa) which is involved in neuronal growth cone collapse. Human DRP-3 showed 94-100% aa identity with two partial peptide sequences of rat TOAD-64 (turned on after division, 64 kDa) which is specifically expressed in postmitotic neurons. Human DHPase and DRPs showed a lower degree of aa sequence identity with Bacillus stearothermophilus hydantoinase (39-42%) and Caenorhabditis elegans unc-33 (32-34%). Thus we describe a novel gene family which displays differential tissue distribution: i.e., human DHPase, in liver and kidney; human DRP-1, in brain; human DRP-2, ubiquitously expressed except for liver; human DRP-3, mainly in heart and skeletal muscle.

CDC20, a potential cancer therapeutic target, is negatively regulated by p53

The p53 protein inhibits malignant transformation through direct and indirect regulation of transcription of many genes related to cell cycle, apoptosis and cellular senescence. A number of genes induced by p53 have been well characterized, but biological significance of genes whose expression was suppressed by p53 is still largely undisclosed. To clarify the roles of p53-suppressive genes in carcinogenesis, we analysed two data sets of whole-genome expression profiles, one for cells in which wild-type p53 was exogenously introduced and the other for a large number of clinical cancer tissues. Here, we identified CDC20 that was frequently upregulated in many types of malignancies and remarkably suppressed by ectopic introduction of p53. CDC20 expression was suppressed by genotoxic stresses in p53- and p21-dependent manners through CDE-CHR elements in the CDC20 promoter. Furthermore, small interference RNA (siRNA)-mediated silencing of p53 induced CDC20 expression in normal human dermal fibroblast cells. As we expected, treatment of cancer cells with siRNA against CDC20 induced G(2)/M arrest and suppressed cell growth. Our results indicate that p53 inhibits tumor cell growth through the indirect regulation of CDC20 and that CDC20 might be a good potential therapeutic target for a broad spectrum of human cancer.

Role of nerve growth factor in cutaneous wound healing: accelerating effects in normal and healing-impaired diabetic mice

Four full-thickness skin wounds made in normal mice led to the significant increase in levels of nerve growth factor (NGF) in sera and in wounded skin tissues. Since sialoadenectomy before the wounds inhibited the rise in serum levels of NGF, the NGF may be released from the salivary gland into the blood stream after the wounds. In contrast, the fact that messenger RNA and protein of NGF were detected in newly formed epithelial cells at the edge of the wound and fibroblasts consistent with the granulation tissue produced in the wound space, suggests that NGF was also produced at the wounded skin site. Topical application of NGF into the wounds accelerated the rate of wound healing in normal mice and in healing-impaired diabetic KK/Ta mice. This clinical effect of NGF was evaluated by histological examination; the increases in the degree of reepithelialization, the thickness of the granulation tissue, and the density of extracellular matrix were observed. NGF also increased the breaking strength of healing linear wounds in normal and diabetic mice. These findings suggested that NGF immediately and constitutively released in response to cutaneous injury may contribute to wound healing through broader biological activities, and NGF improved the diabetic impaired response of wound healing.

Fas-mediated apoptosis in primary cultured mouse hepatocytes

The Fas antigen is a member of the tumor necrosis factor/nerve growth factor receptor family and is expressed in tissues such as the thymus, liver, and ovary. Agonistic anti-Fas antibodies have cytolytic activity against cell lines expressing the Fas antigen. In this study, we show that anti-Fas antibody can induce the death of mouse hepatocytes in primary culture. Cell death via apoptosis was evidenced by the fact that the dying cells displayed DNA fragmentation, extensive surface bleb formation, and chromatin condensation. Anti-Fas antibody alone induced apoptosis in less than 20% of the cultured hepatocytes, whereas all cells were killed within 24 h by anti-Fas antibody in the presence of actinomycin D, cycloheximide, or protein kinase C (PKC) inhibitors such as H-7 and HA1004. These results indicate that the Fas antigen expressed in mouse hepatocytes functionally transduces the apoptotic signal and suggest that cultured mouse hepatocytes express protective proteins against apoptosis and that phosphorylation by PKC is also involved in protection of the hepatocytes from Fas-mediated apoptosis.

Proliferation and differentiation of human osteoblastic cells associated with differential activation of MAP kinases in response to epidermal growth factor, hypoxia, and mechanical stress in vitro

In an attempt to elucidate the specificity of pathways from environmental stress to cellular outcome via mitogen activated protein kinases (MAPKs) activation, we examined the responsiveness of cultured human osteoblastic periodontal ligament (PDL) cells to epidermal growth factor (EGF), hypoxia, and mechanical stress, in terms of cell proliferation, differentiation, and associated activation of three different types of MAPK. Cell proliferation was promoted in the presence of 10ng/ml of EGF or in hypoxic conditions (5% O2), whereas it was inhibited by cyclic stretch (9% strain, 6 cycles/min), which was used as a model of mechanical stress. Conversely, the alkaline phosphatase activity, a marker for osteoblastic differentiation of the cells, was increased by cyclic stretch but decreased by EGF and hypoxia. The mitogenic response of PDL cells to EGF or hypoxia was associated with the selective phosphorylation and activation of extracellular-related kinase (ERK) 1/2, while phosphorylation and activation of c-Jun N-terminal kinase (JNK) was observed in mechanical stretch loaded cells. No such changes were seen in p38 protein. These findings suggested that stress-responsive changes in proliferation and osteoblastic differentiation of PDL cells are selectively mediated by ERK 1/2 and by JNK, respectively, and that a balance between these two pathways determines the cell fate.

Randomized controlled trial of EUS-guided fine needle aspiration techniques for the detection of malignant lymphadenopathy

BACKGROUND

EUS-guided fine needle aspiration (EUS-FNA) is a highly accurate method of detecting malignant lymphadenopathy. The optimal methods for performing EUS-FNA to maximize sensitivity and to minimize the number of needle passes necessary are unknown. This is a report of the results of a prospective randomized controlled trial to determine the effect of suction, the site of FNA (edge or center of lymph node), and the method of preparation of cytologic specimens on accuracy, number of needle passes needed, and specimen quality.

METHODS

Consecutive patients with lymphadenopathy detected by EUS underwent FNA. Each lymph node was sampled with or without suction and from the edge or center in a 2 x 2 factorial design. The samples were expressed onto slides for cytology, and the residual material in the needle was analyzed by the cytospin-cellblock technique. Each aspirate was individually characterized for a diagnosis of malignancy, cellularity, and bloodiness.

RESULTS

Forty-three patients with a total of 46 lymph nodes were evaluated. The final lymph node diagnosis was benign in 22 (48%), "suspicious for malignancy" in 6 (13%), and malignant in 18 (39%). The use of suction was associated with an increase in the cellularity of the specimen, but did not improve the likelihood of obtaining a correct diagnosis (OR 1.52: 95% CI [0.81, 2.85]). Samples obtained with suction were of worse quality because of excessive bloodiness (OR 4.7: 95% CI [1.99, 11.24]). Aspiration from the edge of the lymph node (compared with the center) did not increase the likelihood of a correct diagnosis (OR 1.16: 95% CI [0.42, 3.21]). For 78% of malignant lymph nodes, the correct diagnosis was obtained on the first needle pass and for 100% by the third pass. Cytospin-cellblock methods did not add any additional diagnostic information compared with direct smear cytology.

CONCLUSIONS

The traditional method of applying suction during EUS-FNA does not improve diagnostic accuracy and worsens specimen bloodiness compared with FNA without suction. The site of FNA within the lymph node does not affect accuracy. When EUS-FNA is necessary, our recommendation is up to 3 FNAs without suction from the most convenient and safe location within abnormal-appearing lymph nodes.

Sodefrin: a female-attracting peptide pheromone in newt cloacal glands

A decapeptide called sodefrin was isolated from the abdominal gland of the cloaca of the male red-bellied newt, Cynops pyrrhogaster. The native peptide, as well as the synthetic one, had a female-attracting activity. Sodefrin was found in the apical portion of the epithelial cells of the abdominal gland. Sodefrin is apparently species specific because it did not attract females of Cynops ensicauda. This is the first amphibian pheromone to be identified and the first peptide pheromone identified in a vertebrate.

The vagus nerve is one route of transneural invasion for intranasally inoculated influenza a virus in mice

Intranasally inoculated neurotropic influenza viruses in mice infect not only the respiratory tract but also the central nervous system (CNS), mainly the brain stem. Previous studies suggested that the route of invasion of virus into the CNS was via the peripheral nervous system, especially the vagus nerve. To evaluate the transvagal transmission of the virus, we intranasally inoculated unilaterally vagectomized mice with a virulent influenza virus (strain 24a5b) and examined the distribution of the viral protein and genome by immunohistochemistry and in situ hybridization over time. An asymmetric distribution of viral antigens was observed between vagal (nodose) ganglia: viral antigen was detected in the vagal ganglion of the vagectomized side 2 days later than in the vagal ganglion of the intact side. The virus was apparently transported from the respiratory mucosa to the CNS directly and decussately via the vagus nerve and centrifugally to the vagal ganglion of the vagectomized side. The results of this study, thus, demonstrate that neurotropic influenza virus travels to the CNS mainly via the vagus nerve.

The utility of EUS and EUS-guided fine needle aspiration in detecting celiac lymph node metastasis in patients with esophageal cancer: a single-center experience

BACKGROUND

The aims of this study were to determine the utility of EUS and EUS-guided fine needle aspiration (EUS-FNA) in the detection and confirmation of celiac lymph node metastasis in patients with esophageal cancer and to define EUS features predictive of celiac lymph node metastasis in these patients.

METHODS

The records of 211 patients with esophageal cancer who underwent EUS staging were reviewed. The operating characteristics of EUS were determined in patients where either surgery, EUS-FNA of a celiac lymph node, or both were performed (n = 102). The association between selected variables and the presence of celiac lymph node metastasis was evaluated by univariate and multivariable analyses.

RESULTS

EUS in 48 patients provided a true-positive diagnosis of celiac lymph node involvement, a false-positive and false-negative result, respectively, in 6 and 14 patients, and a true-negative diagnosis in 34 patients. The sensitivity of EUS in detecting celiac lymph node was 77% (95% CI [67, 88]), specificity 85% (95% CI [74, 96]), negative predictive value 71% (95% CI [58, 84]), and the positive predictive value 89% (95% CI [81, 97]). EUS-FNA was performed in 94% (51/54) of patients with celiac lymph nodes. The accuracy of EUS-FNA in detecting malignant celiac lymph nodes was 98% (95% CI [90, 100]). Advanced T-stage, the need for dilation, detection of peritumoral lymph nodes, and black race were associated with celiac lymph node involvement. In multivariable analysis, advanced T-stage was the strongest predictor of celiac lymph node involvement.

CONCLUSION

EUS and EUS-FNA are highly accurate in detecting and confirming celiac lymph nodes metastasis. Depth of tumor invasion as assessed by EUS is a strong predictor of celiac lymph node metastasis in patients with esophageal cancer.

Sequence and over-expression of subunits of adenosine triphosphate synthase in thermophilic bacterium PS3

The primary structures of all the subunits of thermophilic ATP synthase were determined, and its alpha, beta and gamma subunits could be over-expressed in Escherichia coli, because these subunits were stable and reconstitutable. DNA of 7500 base pairs in length was found to contain a cluster of nine genes for subunits of ATP synthase. The order of their reading frames (size in base pairs) was: I(381): a(630): c(216): b(489): delta(537): alpha(1507): gamma(858): beta(1419): epsilon(396), I being a gene for a small hydrophobic, basic protein expressed in vitro. All the termini of TF0F1 subunits were confirmed by peptide sequencing. Large quantities of the overexpressed thermophilic alpha, beta and gamma subunits were prepared from the extract of E. coli, by a few purification steps.

ACAT inhibitors as antiatherosclerotic agents: compounds and mechanisms

Atherosclerosis is a major death cause in western industrialized countries. A diagnosing system, medical prevention, and treatment of atherosclerosis is not sufficient so far. A direct acting antiatherosclerotic agent is eagerly waited. ACAT inhibitor approach could provide such an agent. In the formation of atherosclerosis, cholesteryl esters, which are the lipids which accumulate in atheromatous plaques by an aid of macrophages and smooth muscle cells, forming foam cells, may play an important role. ACAT enzyme is responsible for the acylation of cholesterol to cholesteryl esters, a transformation which can be essential in not only cholesteryl esters accumulation at arterial walls but also the absorption of cholesterol in the intestine and the excretion of cholesterol in the liver. From these points, ACAT inhibitors might work against atherosclerosis in three different ways: first, cholesteryl ester accumulation inhibition at arterial walls could be a direct antiatherosclerotic effect; second, cholesterol absorption inhibition at the intestine; and third, cholesterol excretion acceleration at the liver, while the later two effects would result in a reduction of blood cholesterol level--a major risk factor of atherosclerosis. Taking account of this discussion, the ACAT inhibitors would be potent antiatherosclerotic agents. Medicinal research has been contributing full strength to produce an ultimate compound. These efforts should provide a drug which will be useful to patients.

A genome-wide association study identifies two novel susceptibility loci and trans population polygenicity associated with bipolar disorder

Genome-wide association studies (GWASs) have identified several susceptibility loci for bipolar disorder (BD) and shown that the genetic architecture of BD can be explained by polygenicity, with numerous variants contributing to BD. In the present GWAS (Phase I/II), which included 2964 BD and 61 887 control subjects from the Japanese population, we detected a novel susceptibility locus at 11q12.2 (rs28456, P=6.4 × 10-9), a region known to contain regulatory genes for plasma lipid levels (FADS1/2/3). A subsequent meta-analysis of Phase I/II and the Psychiatric GWAS Consortium for BD (PGC-BD) identified another novel BD gene, NFIX (Pbest=5.8 × 10-10), and supported three regions previously implicated in BD susceptibility: MAD1L1 (Pbest=1.9 × 10-9), TRANK1 (Pbest=2.1 × 10-9) and ODZ4 (Pbest=3.3 × 10-9). Polygenicity of BD within Japanese and trans-European-Japanese populations was assessed with risk profile score analysis. We detected higher scores in BD cases both within (Phase I/II) and across populations (Phase I/II and PGC-BD). These were defined by (1) Phase II as discovery and Phase I as target, or vice versa (for 'within Japanese comparisons', Pbest~10-29, R2~2%), and (2) European PGC-BD as discovery and Japanese BD (Phase I/II) as target (for 'trans-European-Japanese comparison,' Pbest~10-13, R2~0.27%). This 'trans population' effect was supported by estimation of the genetic correlation using the effect size based on each population (liability estimates~0.7). These results indicate that (1) two novel and three previously implicated loci are significantly associated with BD and that (2) BD 'risk' effect are shared between Japanese and European populations.

Common variant in 6q26-q27 is associated with distal colon cancer in an Asian population

BACKGROUND AND AIM

Colorectal cancer (CRC) is a multifactorial disease with both environmental and genetic factors contributing to its development. The incidence of CRC is increasing year by year in Japan. Patients with CRC in advanced stages have a poor prognosis, but detection of CRC at earlier stages can improve clinical outcome. Therefore, identification of epidemiologial factors that influence development of CRC would facilitate the prevention or early detection of disease.

METHODS

To identify loci associated with CRC risk, we performed a genome-wide association study (GWAS) for CRC and sub-analyses by tumour location using 1583 Japanese CRC cases and 1898 controls. Subsequently, we conducted replication analyses using a total of 4809 CRC cases and 2973 controls including 225 Korean subjects with distal colon cancer and 377 controls.

RESULTS

We identified a novel locus on 6q26-q27 region (rs7758229 in SLC22A3, p = 7.92 × 10⁻⁹, OR of 1.28) that was significantly associated with distal colon cancer. We also replicated the association between CRC and SNPs on 8q24 (rs6983267 and rs7837328, p = 1.51 × 10⁻⁸ and 7.44 × 10⁻⁸, ORs of 1.18 and 1.17, respectively). Moreover, we found cumulative effects of three genetic factors (rs7758229, rs6983267, and rs4939827 in SMAD7) and one environmental factor (alcohol drinking) which appear to increase CRC risk approximately twofold.

CONCLUSIONS

We found a novel susceptible locus in SLC22A3 that contributes to the risk of distal colon cancer in an Asian population. These findings would further extend our understanding of the role of common genetic variants in the aetiology of CRC.

Ring chromosome 20 and nonconvulsive status epilepticus. A new epileptic syndrome

Six cases of epilepsy associated with ring chromosome 20 are presented. The study of these cases and 20 cases reported in the literature revealed that they constitute a distinct epileptic syndrome: frequent seizures consisting of a prolonged confusional state, with or without additional motor seizures, and an ictal EEG pattern of long-lasting bilateral paroxysmal high-voltage slow waves with occasional spikes. Neurological examination results were normal, and neuroimaging studies often failed to disclose a brain lesion. The seizures were resistant to antiepileptic drug therapy. Comparison of the electroclinical features of nonconvulsive status epilepticus in six patients with and four patients without ring chromosome 20 revealed that the group with the chromosomal anomaly had more frequent, comparatively brief episodes of confusion associated with a less prominent spike component on the EEG. We propose that epilepsy associated with ring chromosome 20 constitutes a new syndrome that may provide an opportunity to scrutinize a genetic mechanism of epilepsy.

Expression cloning and functional characterization of human cDNA for ganglioside GM3 synthase

Ganglioside GM3 is a major glycosphingolipid in the plasma membrane and is widely distributed in vertebrates. We describe here the isolation of a human cDNA whose protein product is responsible for the synthesis of GM3. The cloned cDNA spanned 2,359 base pairs, with an open reading frame encoding a protein of 362 amino acids with a predicted molecular mass of 41.7 kDa. The deduced primary structure shows features characteristic of the sialyltransferase family, including a type II transmembrane topology and the sialylmotifs L at the center and S at the C-terminal region. An amino acid substitution from aspartic acid to histidine was demonstrated at a position invariant in sialylmotif L of all the other sialyltransferases so far cloned. The best acceptor substrate for the gene product was lactosylceramide, and cells transfected with the cloned cDNA clearly exhibited de novo synthesis of GM3, with a measurable decrease in the precursor lactosylceramide. Despite the ubiquitous distribution of ganglioside GM3 in human tissues, a major 2.4-kilobase transcript of the gene was found in a tissue-specific manner, with predominant expression in brain, skeletal muscle, and testis, and very low expression in liver.

Photochromism of diarylethenes with two nitronyl nitroxides: photoswitching of an intramolecular magnetic interaction

Photochromic diarylethenes that have p-phenylene-substituted benzothiophene aryl groups with and without nitronyl nitroxide radicals at both ends of the molecules were synthesized. The absorption maxima of the closed-ring isomers showed a hypsochromic shift with the increase in the pi-conjugated chain length. The unique behavior was attributed to the stabilization by the resonant quinoid structures. Both photocyclization and photocycloreversion quantum yields of the diarylethene with nitronyl nitroxide radicals were found to increase with the increase in the pi-conjugated chain length. Photoswitching of the magnetic interaction between two nitronyl nitroxide radicals was studied by means of ESR spectroscopy. The change in exchange interaction between open- and closed-ring isomers of 1,2-bis[6-[4-[4-(1-oxyl-3-oxide-4,4,5,5-tetramethylimidazolin-2-yl)phenyl]phenyl]-2-methyl-1-benzothiophen-3-yl]hexafluorocyclopentene was determined to be more than 30-fold.

Edit, cut and paste in the nicotinic acetylcholine receptor gene family ofDrosophila melanogaster

Nicotinic acetylcholine receptors (nAChRs) are important for fast synaptic cholinergic transmission. They are targets of drugs/chemicals for human and animal health as well as for pest control. With the advent of genome sequencing, entire nAChR gene families have now been described for vertebrates and invertebrates. Mostly, these are extensive with a large number of distinct subunits, making possible many nAChR subtypes differing in transmitter affinity, channel conductance, ion selectivity, desensitization, modulation and pharmacology. The smallest nAChR gene family to date is that of the fruit fly, Drosophila melanogaster, with only 10 members. This apparently compact family belies its true diversity as 4 of the 10 subunits show alternative splicing. Also, using Drosophila, A-to-I pre-mRNA editing has been demonstrated for the first time in nAChRs. Such is the extent of this variation, that one subunit alone (Dalpha6) can potentially generate far more isoforms than seen in entire gene families from other species. We present here three-dimensional models constructed for insect nAChRs, which show that many variations introduced by alternative splicing and RNA editing may influence receptor function.

Reduction of PTEN protein and loss of epidermal growth factor receptor gene mutation in lung cancer with natural resistance to gefitinib (IRESSA)

Gefitinib (IRESSA), an epidermal growth factor receptor (EGFR) tyrosine kinase (TK) inhibitor, has antitumour activity in the advanced non-small-cell lung cancer (NSCLC) setting. However, in chemotherapy-naïve patients with advanced NSCLC, the addition of gefitinib to standard chemotherapy regimens failed to increase survival. These results suggest the need for improved patient selection and combination rationales for targeted therapies. We have identified subpopulations of an adenocarcinoma cell line that are naturally resistant to gefitinib, and have analysed the cDNA expression profiles, genomic status of EGFR gene and the effect of gefitinib on signalling pathways in these cell lines in order to identify key mechanisms for naturally acquired resistance to gefitinib. Gefitinib-resistant subpopulations demonstrated increased Akt phosphorylation (not inhibited by gefitinib), reduced PTEN protein expression and loss of the EGFR gene mutation when compared with parental cell lines. These differences in Akt and PTEN protein expression were not evident from the cDNA array profiles. These data suggests that (1) the EGFR gene mutation may be possibly lost in some cancer cells with other additional mechanisms for activating Akt, (2) reintroduction of PTEN or pharmacological downregulation of the constitutive PI3K-Akt-pathway activity may be an attractive therapeutic strategy in cancers with gefitinib resistance.

Regulation by orexin of feeding behaviour and locomotor activity in the goldfish

Orexin is a hypothalamic neuropeptide that is implicated in the regulation of feeding behaviour and the sleep-wakefulness cycle in mammals. However, in spite of a growing body of knowledge concerning orexin in mammals, the orexin system and its function have not been well studied in lower vertebrates. In the present study, we first examined the effect of feeding status on the orexin-like immunoreactivity (orexin-LI) and the expression of orexin mRNA in the goldfish brain. The number of cells showing orexin-LI in the hypothalamus of goldfish brain showed a significant increase in fasted fish and a significant decrease in glucose-injected fish. The expression level of orexin mRNA in the brains of fasted fish increased compared to that of fed fish. We also examined the effect of an i.c.v. injection of orexin or an anti-orexin serum on food intake and locomotor activity in the goldfish. Administration of orexin by i.c.v. injection induced a significant increase of food intake and locomotor activity, whereas i.p. injection of glucose or i.c.v. injection of anti-orexin serum decreased food consumption. These results indicate that the orexin functions as an orexigenic factor in the goldfish brain.