Effects of CCK2 receptor blockade on growth parameters in gastrointestinal tract and pancreas in rats

Gastrin has a growth-promoting effect on the oxyntic mucosa of the stomach but has been claimed also to affect other parts of the gastrointestinal tract and pancreas. This report describes the effects of the cholecystokinin, (CCK2) receptor antagonists YM022 and YF476 on various growth parameters in the gastrointestinal tract and pancreas of the rat. YM022 and YF476 were given subcutaneously in doses known to produce maximum and sustained CCK2 receptor blockade. The body weight was not affected. However, the oxyntic mucosal weight, thickness and protein and DNA contents were reduced by 15-20% already within 1-2 days and by about 30% after 4-8 weeks of CCK2 receptor blockade. Hence, the response of the oxyntic mucosa to CCK2 receptor blockade was in the form of hypotrophy (reduced protein content) and hypoplasia (reduced DNA content). There were no obvious effects of CCK2 receptor blockade on the intestine or pancreas (nor on liver, kidney or thyroid). The proton pump inhibitor omeprazole was used to induce hypergastrinaemia and was given with or without YM022. Omeprazole treatment for 4 weeks increased the oxyntic mucosal weight and thickness by 15-20%. YM022 prevented these effects. We conclude that while elevated circulating gastrin levels, acting on CCK2 receptors, exert a growth-promoting effect on the oxyntic mucosa (but not elsewhere), normal serum gastrin levels exert a mucosa-preserving effect.

Long-term omeprazole treatment suppresses body weight gain and bone mineralization in young male rats

BACKGROUND

The stomach is rich in endocrine cells, including those producing ghrelin, which is thought to play a role in the control of body growth. Omeprazole treatment is associated with hypergastrinaemia, resulting in growth of the oxyntic mucosa in general and the enterochromaffin-like (ECL) cells in particular. In the present study, we examined the effects of long-term omeprazole treatment on young male rats with respect to body growth and stomach.

METHODS

Male rats (24 days old) were treated with omeprazole (400 micromol/kg/day) or vehicle for 77 days. The body weight was recorded twice per week. At sacrifice, dual-energy X-ray absorptiometry (DXA) was used to assess total bone area, bone mineral content (BMC), bone mineral density (BMD) and body composition (fat and lean body mass). The lengths of the spine and the femur were recorded. The plasma concentrations of gastrin and histamine were determined by radioimmunoassays. The endocrine cells of the stomach were examined by immunocytochemistry.

RESULTS

The body weight gain was suppressed by omeprazole treatment. The bone area, BMC and BMD were reduced, while the lengths of the spine and the femur and the body composition were unchanged. Omeprazole-induced hypergastrinaemia was associated with enlargement of the oxyntic area and with hyperplasia of ECL cells but not of A-like cells and D cells. In contrast, the enterchromaffin (EC) cell density in the antrum was reduced.

CONCLUSIONS

Omeprazole treatment of young male rats reduces body weight and bone mass gain. The densities of ECL cells in the oxyntic mucosa was increased and of the EC cells in the antral mucosa reduced.

Competence development by Haemophilus influenzae is regulated by the availability of nucleic acid precursors

DNA uptake by naturally competent bacteria provides cells with both genetic information and nucleotides. In Haemophilus influenzae, competence development requires both cAMP and an unidentified signal arising under starvation conditions. To investigate this signal, competence induction was examined in media supplemented with nucleic acid precursors. The addition of physiological levels of AMP and GMP reduced competence 200-fold and prevented the normal competence-induced transcription of the essential competence genes comA and rec-2. The rich medium normally used for growth allows only limited competence. Capillary electrophoresis revealed only a subinhibitory amount of AMP and no detectable GMP, and the addition of AMP or GMP to this medium also reduced competence 20- to 100-fold. Neither a functional stringent response system nor a functional phosphoenolpyruvate:glycose phosphotransferase system (PTS) was found to be required for purine-mediated repression. Added cAMP partially restored both transcription of competence genes and competence development, suggesting that purines may reduce the response to cAMP. Potential binding sites for the PurR repressor were identified in several competence genes, suggesting that competence is part of the PUR regulon. These observations are consistent with models of competence regulation, in which depleted purine pools signal the need for nucleotides, and support the hypothesis that competence evolved primarily for nucleotide acquisition.

Identification of sequences in rotavirus mRNAs important for minus strand synthesis using antisense oligonucleotides

The core of the rotavirion consists of three proteins, including the viral RNA polymerase, and 11 segments of double-stranded (ds)RNA. The RNA polymerase of disrupted (open) cores is able to catalyze the synthesis of dsRNA from exogenous viral mRNAs in vitro. In this study, we have identified sequences in exogenous viral mRNAs important for RNA replication using antisense oligonucleotides. The results showed that oligonucleotides complementary to the highly conserved 3'-terminal sequence of rotavirus mRNAs prevented all but basal levels of dsRNA synthesis. Notably, we observed that the addition of oligonucleotides which were complementary to nonconserved sequences present either at the 5'- or 3'-end of a viral mRNA effectively inhibited its replication without interfering with the replication of other viral mRNAs present in the same replication assay. Thus, the nonconserved sequences in rotavirus mRNAs contain gene-specific information that promotes RNA replication. The fact that antisense oligonucleotides inhibited dsRNA synthesis indicates that the strandedness (single- versus double-stranded) and secondary structure of the viral mRNA template are factors that affect the efficiency of minus strand synthesis.

Eye irritation caused by formaldehyde as an indoor air pollution--a controlled human exposure experiment

OBJECTIVE

The present study focuses on health assessment of wood based panels which are widely used in interior decoration practices over the recent years in China. Formaldehyde has been identified as chemical indicator of (IAO) and an indoor air pollutant. To test its health effects experiment was undertaken.

METHOD

A small environmental test chamber (60/L) was used as the generator of emission gas from new panels, and was operating at a temperature of 22.7 +/- 0.6 degrees C and a humidity of 44.4 +/- 2.5% with an air exchange rate of 1.0 +/- 0.15 h-1. On the three experimental days the values of product loading in chamber were 4, 2 and 6 m2/m3, respectively. Eight people were selected randomly from the students and employees of Wuhan Health and Anti-epidemic Station as subjects, with an average age of 21.9 +/- 5.9 years, and a gender ratio of 1:1, and two of them were smokers (one male and one female). The subjects' eyes were exposed to formaldehyde through a pair of goggles. Each goggle had its flow inlet and outlet, and connected to chamber exhaust of emission gas and to an exhaust from the room. The exposure time was very short, just 5 minutes and the formaldehyde doses were at 1.65 +/- 0.01, 2.99 +/- 0.07 and 4.31 +/- 0.02 ppm. A 60-mm linear visual analogue rating scales was used to measure the intensity of sensory eye irritation and a video tape recorder was used to record eye blinking frequency.

RESULTS

The results demonstrated that tests of sensory eye irritation and eye blinking can be used for materials testing, and that a dose-effect as well as a time-variance of the effect can be measured.

CONCLUSION

The tests showed that eye irritation was perceived at all of the three levels.

[Immunological regulations of dendritic cell in abnormal scarring tissue]

OBJECTIVE

To investigate the relationship between dendritic cell(DC) and pathogenesis of abnormal scar.

METHODS

The content of HLA-DR and CD1a molecules of DC, in 6 samples of hypertrophic scar (HS), keloid (K) and normal skin, were determined with the stain of avidin-biotin-peroxidase complex method (ABC). The effect of Triamcinolone Acetonide was evaluated with the measurement of the HLA-DR and CD1a molecules of DC in the epidermis of the HS.

RESULTS

1. The amounts of HLA-DR molecules of the positive DC were 806.67 +/- 101.72 and 870.00 +/- 134.24 in the HS and the K respectively, significantly higher than the controlled normal skin (510.01 +/- 45.17, P < 0.05). HLA-DR molecules showed an abnormal expression in the Kerationcytes and fibroblasts. 2. The amounts of CD1a molecules of the positive DC were 700.00 +/- 97.23 and 780.00 +/- 104.47 in the HS and the K respectively, significantly higher than the controlled normal skin (521.24 +/- 57.87)(P < 0.05). 3. The amounts of the HLA-DR molecules positive DC, in the positive kerationcytes and fibroblasts of hypertrophic scar, treated by Triamcinolone Acetonide, were 476.67 +/- 70.02 and 447.76 +/- 90.03 (P < 0.05) for 3 days and 7 days treatment respectively, significantly lower than the control. The amounts of CD1a molecules positive DC in the epidermis of hypertrophic scar with the injection of Triamcinolone Acetonide were significantly lower in 3 days and 7 days treatment (456.36 +/- 82.88 and 397.18 +/- 99.36, P < 0.05).

CONCLUSION

1. The results, with the high expression of HLA-DR and CD1a molecules, indicate that the HS and the K may have strong immune reactions. 2. Triamcinolone Acetonide may decrease the immune reactions of the HS, through the inhibition of the expressions of HLA-DR and CD1a molecules in the dendritric cell.

[Pre- and post-contrast multiphase helical CT in the diagnosis of hepatic focal nodular hyperplasia]

OBJECTIVE

To analyse the pre- and post-contrast CT findings of liver focal nodular hyperplasia (FNH), so as to improve its diagnostic accuracy.

METHODS

Pre-contrast scan and post-contrast tri-phase scan (arterial phase, portal venous phase and delayed phase) were performed in 21 patients with FNH which were proved surgically and pathologically. Transcatheter arterial angiography was performed in 2 patients.

RESULTS

On pre-contrast scans, 16 of 21 lesions were hypodense, 5 of 21 were isodense. Twelve of 21 lesions showed punctate, streak and radial scar. On the arterial phase scans, all the lesions were markedly and homogeneously enhanced, except for the central scar. Nine of 21 lesions showed dilated and tortuous arteries at the central or peripheral area. On the portal venous phase scans, focal density was decreased, but still showing hyperdense or slightly hyperdense relative to the normal liver. On the delay phase scans, the lesions changed to isodense or slightly hypodense. Enhanced capsule was observed in 3 patients. On the angiography images, dilated arteries and drainage veins were seen.

CONCLUSION

FNH has its special characteristics on the multiphasic helical CT scan. It is of great value in diagnosing the FNH and in choosing the appropriate therapy.

[Cytotoxicity of the strontium-substituted hydroxyapatite evaluated by MTT colorimetry]

This study was conducted to evaluate the cytotoxicity of strontium-substituted hydroxyapatite by methyl thiazolyl tetrazolium (MTT) colorimetry. We used the MTT method to assay the cytotoxicity of the strontium-substituted hydroxyapatite containing different strontium concentrations (1%, 5%, 10%, 100% Sr2+) and the pure hydroxyapatite. The results showed that the cytotoxicity scores of the different materials were grade 0 or grade 1. These led us to the conclusion that strontium-substituted hydroxyapatite has good biocompatibility.

Serum and mucosal immune responses to an inactivated influenza virus vaccine induced by epidermal powder immunization

Both circulating and mucosal antibodies are considered important for protection against infection by influenza virus in humans and animals. However, current inactivated vaccines administered by intramuscular injection using a syringe and needle elicit primarily circulating antibodies. In this study, we report that epidermal powder immunization (EPI) via a unique powder delivery system elicits both serum and mucosal antibodies to an inactivated influenza virus vaccine. Serum antibody responses to influenza vaccine following EPI were enhanced by codelivery of cholera toxin (CT), a synthetic oligodeoxynucleotide containing immunostimulatory CpG motifs (CpG DNA), or the combination of these two adjuvants. In addition, secretory immunoglobulin A (sIgA) antibodies were detected in the saliva and mucosal lavages of the small intestine, trachea, and vaginal tract, although the titers were much lower than the IgG titers. The local origin of the sIgA antibodies was further shown by measuring antibodies released from cultured tracheal and small intestinal fragments and by detecting antigen-specific IgA-secreting cells in the lamina propria using ELISPOT assays. EPI with a single dose of influenza vaccine containing CT or CT and CpG DNA conferred complete protection against lethal challenges with an influenza virus isolated 30 years ago, whereas a prime and boost immunizations were required for protection in the absence of an adjuvant. The ability to elicit augmented circulating antibody and mucosal antibody responses makes EPI a promising alternative to needle injection for administering vaccines against influenza and other diseases.

Prostate-specific targeting using PSA promoter-based lentiviral vectors

The prostate-specific antigen (PSA) promoter is known to be highly tissue specific. Although its tissue specificity has been confirmed, its efficiency of gene transcription is significantly lower compared to known nonspecific viral promoters. These lower levels of promoter activity therefore pose a problem when developing an efficacious gene vector for prostate cancer gene therapy. Thus, selecting an appropriate therapeutic gene and vector system to carry the gene driven by the PSA promoter (PSAP) is important. In the studies described here, a human immunodeficiency virus (HIV)-1-based lentiviral vector carrying either the enhanced green fluorescent protein (EGFP) reporter or the diphtheria toxin A (DTA) gene was constructed. The results demonstrate that the PSA promoter in a lentiviral vector drives genes in prostate cells with satisfactory efficacy and specificity. The tissue-specific expression of the DTA protein efficiently eradicates LNCaP prostate cells in culture. We also infected prostate cancer cells and control cells carried by nude mice with the EGFP lentiviral vector. Significant numbers of EGFP-positive LNCaP cells were detected in all the mice bearing these tumors, but no EGFP-positive control cells were detected in any other mouse tissue. The high levels of expression in prostate cells, compared with the low levels of background expression in other cells, show that the PSAP-lentiviral vector could be a potential useful tool for gene therapy of metastatic prostate cancer.

Purification and characterization of White Spot syndrome virus (WSSV) produced in an alternate host: crayfish, Cambarus clarkii

Penaeid shrimp is the natural host of White Spot Syndrome Virus (WSSV) that can cause high mortality in the infected hosts. Attempts to obtain sufficient amounts of purified intact WSSV for characterization have been unsuccessful. Using crayfish, Cambarus clarkii as a proliferation system, a large amount of infectious WSSV was reproduced and intact WSSV viral particles were purified with a new isolation medium by ultra-centrifugation. Purified WSSV particles were very sensitive to organic solvents and the detergent, Triton X-100. The size of the rod-shape, somewhat elliptical, intact WSSV was 110-130x260-350 nm with a long, tail-like envelope extension. The naked viral nucleocapsid was about 80x350 nm, and it possessed 15 spiral and cylindrical helices composed of 14 globular capsomers along its long axis, and a 'ring' structure at one terminus. Distinct WSSV genome DNA patterns were obtained when the purified genomic dsDNA of WSSV was digested with five different restriction enzymes (HindIII, XhoI, BamHI, SalI, and SacI). In addition, at least 13 major and distinct protein bands could be observed when purified intact WSSV viruses were separated by SDS-PAGE followed by Coomassie Brilliant R-250 staining. The estimated molecular weights of these proteins were 190, 84, 75, 69, 68, 58, 52, 44, 28, 27.5, 23, 19, and 16 kD, respectively. Both the 44 and 190 kD proteins were easily removed if the hemolymph from the WSSV infected crayfish was transiently treated with 1% Triton X-100 before it was subjected to gradient centrifugation, indicating that both of them are located on the surface of the viral envelope. These characteristics are consistent with WSSV isolated from the penaeid shrimp.

Minimal regions of chromosomal imbalance in retinoblastoma detected by comparative genomic hybridization

Mutation of both alleles of the retinoblastoma gene (RB1) initiate oncogenesis in developing human retina, but other common genomic alterations are present in the tumors. In order to sublocalize the altered genomic regions, 50 retinoblastoma tumors were examined by comparative genomic hybridization (CGH). The minimal regions most frequent gained were 1q31 (52%), 6p22 (44%), 2p24-p25 (30%) and 13q32-q34 (12%). The minimal region most frequently lost was 16q22 (14%). The overall total number of gains or losses evident on CGH was significantly greater in those tumors with either or both 6p or 1q gain, than in tumors with neither 6p nor 1q gain suggesting that chromosomal instability may be associated with acquisition of these changes. Genes mapping to 6p22 and 1q31 may be important in tumor development in retina subsequent to the loss of RB1 alleles.

Enforced expression of the GATA-3 transcription factor affects cell fate decisions in hematopoiesis

OBJECTIVE

Three GATA family transcription factors are involved in various aspects of hematopoiesis. Their lineage-restricted expression correlates well with their function in selective lineage commitment and differentiation. We focused on the role of GATA-3 to determine whether an intrinsic variation among different GATA proteins, in addition to the distinct expression pattern, determines lineage specification.

MATERIALS AND METHODS

Using a retroviral vector, we introduced the GATA-3 gene into primary murine hematopoietic stem cells (HSC) and examined their development in in vitro suspension culture and colony-forming assays as well as in vivo competitive repopulation studies.

RESULTS

Although GATA-3 expression normally is restricted to lymphoid precursor and committed T cells, overexpression of GATA-3 in HSC results in cessation of cell expansion followed by selective induction of megakaryocytic and erythroid differentiation and inhibition of myeloid and lymphoid precursor development in liquid suspension culture and in vitro colony-forming assays. Competitive repopulation studies show that transplanted GATA-3-expressing HSC/progenitor cells give one wave of erythrocyte development but fail to expand in the bone marrow or to reconstitute other lineages.

CONCLUSIONS

The selective megakaryocytic/erythroid differentiation in HSC with enforced GATA-3 expression suggests a functional redundancy among GATA proteins and indicates that the specific lineage fate determination by individual GATA proteins is largely regulated at the level of expression in a lineage and developmental-stage restricted fashion, whereas the identity of the GATA factor may not be as important.

[Expression of human leucocyte antigen in ectopic endometrial tissue of endometriosis]

OBJECTIVE

To investigate the human leucocyte antigen (HLA) expression of ectopic endometrial epithelial cells in cases with endometriosis and its role in pathogenesis of endometriosis.

METHODS

By immunohistochemical analysis, HLA expression was observed in ectopic endometrial epithelial cells of 25 endometriosis patients. Ectopic endometrial cells were cultured in vitro successfully and the expression of HLA were analyzed by flow cytometry in 10 out of the 25 patients. Eutopic endometrium of 15 normal women were taken as control.

RESULTS

(1) Expression of HLA class I molecule on ectopic endometrial epithelial cells of endometriosis measured by the immunohistochemical analysis was lower than those of controls, (4.0 +/- 0.5) score and (1.2 +/- 0.8) score respectively. So was the expression rate by flow cytometry in vitro culture (63.38 +/- 11.88)% and (5.27 +/- 2.88)% respectively (P < 0.01). (2) The expression of HLA class II molecule on ectopic endometrial epithelial cells of endometriosis was significantly increased. The outcome by immunohistochemical analysis was (0.2 +/- 0.1) score (control group) and (4.1 +/- 0.7) score (case group) and by flow cytometry was (7.19 +/- 2.43)% and (58.57 +/- 14.99)% respectively (P < 0.01).

CONCLUSIONS

The abnormal HLA expression could play a role in the pathogenesis of endometriosis.

Analysis of trace amino acid neurotransmitters in hypothalamus of rats after exhausting exercise using microdialysis

A simple but effective coupling of microdialysis and capillary electrophoresis with laser induced fluorescence detection technique was applied to analysis of amino acid neurotransmitters in the hypothalamus of rats after acute exhausting exercise. The separation of amino acids was achieved using an uncoated fused-silica capillary (57 cm x 75 microm I.D.) with a buffer of 10 mM disodium tetraborate at pH 10 and an applied voltage of 12.5 kV. The detection limit was 10(-10) M for each amino acid. It is sufficiently sensitive and rapid for the determination of amino acids in a 5-microl Microdialysate. In comparison to pre-exercise, a significant increase in the levels of six hypothalamic amino acids (arginine, glycine, lysine, glutamic acid, alanine, gamma-amino-n-butyric acid) was found after exercise. These results demonstrate that the increase of metabolic amino acids in the hypothalamus of rats can be induced by exhausting exercise and suggests that amino acid neurotransmitters may play functional roles in the central effects of exercise.

Comparison of valve resistance with effective orifice area regarding flow dependence

Aortic valve resistance has been proposed to represent the severity of aortic stenosis because some studies observed that it was less affected by change in flow than the valve-effective orifice area, but this issue remains controversial. The objective of this study was to systematically analyze the theoretical and practical determinants of these parameters in relation to changes in flow. Valve area and resistance in different valves were studied in vitro in a pulse duplicator system at different flow rates and in vivo in 90 subjects referred to either exercise or dobutamine infusion. Theoretical analysis and experimental results both demonstrated a unique relation between resistance (RES), valve-effective orifice area (EOA), and flow rate (Q): RES = K x (Q/EOA(2)). Accordingly, in fixed stenoses or in mechanical valves, resistance increased markedly with flow rate both in vitro (+0.88 +/- 0.26%/% of flow increase) and in vivo (mechanical valves: +2.09 +/- 4.61, fixed stenotic valves: +0.59 +/- 0.32%/%), whereas valve area did not change significantly (<0.2%/%). In contrast, in valves with a flexible orifice (bioprostheses and some patients with aortic stenosis), resistance was less increased due to the increase in valve area. Thus, both from a theoretical and a practical standpoint, valve resistance is much more flow dependent than valve area, particularly in fixed stenoses. Situations in which resistance does not increase with flow rate are unpredictable and are found in flexible valves when there is a concomitant increase in valve area.

[Therapeutic effects of nitroglycerin on pregnancy induced hypertension]

OBJECTIVE

To evaluate the effects and possibility of nitroglycerin on Pregnancy induced hypertension (PIH) treatment.

METHODS

In comparison with the third trimester normal pregnant women (Normal group) (n = 11), 34 moderate/severe PIH cases were divided into three groups: PIH treated only with magnesium sulfate (Mg group) (n = 11); PIH treated only with nitroglycerin (Ng group) (n = 11); and PIH treated with Mg + Ng (Combination group) (n = 12). The endothelial nitric oxide synthase (eNOS) in placenta was investigated immunohistochemically and quantitatively. Data such as platelet aggregation (PAg), umbilical artery of S/D ratio and resistance index (RI) with color Doppler and the effect of decrement of blood pressure on PHI groups were evaluated.

RESULTS

In comparision with Normal group, (1) the quantity of eNOS of PIH cases was significantly lower (P < 0.01). (2) umbilical artery S/D ratio and RI in Ng group were significantly lower after introvascular drip of Ng (P < 0.05). (3) Pag in Ng group and Combination group decreased significantly after treatment (P < 0.01), but no difference in Mg group. (4) the decrement of blood pressure on PIH groups, compared with Mg group, was significant in Ng group and Combination groups (P < 0.05).

CONCLUSIONS

Ng can reduce blood pressure, fetal-placenta circulation resistance, and inhibit PAg. It probably play a role on intrauterine growth retardation (IUGR) caused by PIH.

Tofu consumption and blood lead levels in young Chinese adults

Tofu is a commonly consumed food in China. Tofu may interfere with lead absorption and retention because of its high calcium content. In this observational study, the authors examined whether dietary tofu intake was associated with blood lead levels among young adults in Shenyang, China. The analyses included 605 men and 550 women who completed baseline questionnaires and had blood lead measurements taken in 1996-1998 as part of a prospective cohort study on reproductive health. Mean blood lead levels were 13.2 microg/dl in men and 10.1 microg/dl in women. Blood lead levels were negatively associated with tofu intake in both genders. A linear trend test showed a 3.7% (0.5-microg/dl) decrease in blood lead level with each higher category of tofu intake (p = 0.003). The highest tofu intake group (> or =750 g/week) had blood lead levels 11.3% lower (95% confidence interval: 4.1, 18.0) than those of the lowest tofu intake group (<250 g/week). In all regression models, data were adjusted for gender, age, height, body mass index, district, cigarette smoking, alcohol drinking, education, occupation, use of vitamin supplements, season, and dietary intake of meat, fish, vegetables, eggs, and milk. In conclusion, the authors found a significant inverse dose-response relation between tofu consumption and blood lead levels in this Chinese population.

A-like cells in the rat stomach contain ghrelin and do not operate under gastrin control

Ghrelin is a 28 a.a. gastric peptide, recently identified as a natural ligand of the growth hormone secretagogue receptor (orphan receptor distinct from the receptor for growth hormone releasing hormone). In the present study, radioimmunoassay demonstrated ghrelin-like material in the rat oxyntic mucosa with moderate amounts also in antrum and duodenum. Small amounts were found in the distal intestines and pancreas. Northern blot analysis revealed abundant ghrelin mRNA in the oxyntic mucosa. Immunocytochemistry demonstrated ghrelin-immunoreactivity in endocrine-like cells in the oxyntic mucosa. Such cells occurred in low numbers also in the antrum and duodenum. The rat oxyntic mucosa is rich in endocrine (chromogranin A/pancreastatin-immunoreactive) cells, such as the histamine-rich ECL cells (65-75% of the endocrine cells), the A-like cells (20-25%) and the D cells (somatostatin cells) (10%). The ghrelin-immunoreactive (IR) cells contained pancreastatin but differed from ECL cells and D cells by being devoid of histamine-forming enzyme (ECL cell constituent) and somatostatin (D cell constituent). Hence, ghrelin seems to occur in the A-like cells. The ghrelin-IR cells in the antrum were distinct from the gastrin cells, the serotonin-containing enterochromaffin cells and the D cells. Conceivably, ghrelin cells in the antrum and distally in the intestines also belong to the A-like cell population. The concentration of ghrelin in the circulation was lowered by about 80% following the surgical removal of the acid-producing part of the stomach in line with the view that the oxyntic mucosa is the major source of ghrelin. The serum ghrelin concentration was higher in fasted rats than in fed rats; it was reduced upon re-feeding and seemed unaffected by 1-week treatment with the proton pump inhibitor omeprazole, resulting in elevated serum gastrin concentration. Infusion of gastrin-17 for 2 days failed to raise the serum ghrelin concentration. Omeprazole treatment for 10 weeks raised the level of HDC mRNA but not that of ghrelin mRNA or somatostatin mRNA in the oxyntic mucosa. Hence, unlike the ECL cells, ghrelin-containing A-like cells do not seem to operate under gastrin control.

Nonsteroidal anti-inflammatory drugs induce apoptosis in esophageal cancer cells by restoring 15-lipoxygenase-1 expression

In previous studies, we have found that expression of 15-lipoxygenase-1 (15-LOX-1) and its main product, 13-S-hydroxyoctadecadienoic acid, are decreased in human colorectal cancers and that nonsteroidal anti-inflammatory drugs (NSAIDs) can therapeutically induce 15-LOX-1 expression to trigger apoptosis in human colorectal cancer cells. NSAIDs similarly induce apoptosis in esophageal cancer cells, although the mechanisms of these effects remain to be defined. In the present study, we tested whether 15-LOX-1 is down-regulated in human esophageal cancers using paired normal and tumor human surgical samples and whether NSAIDs can up-regulate 15-LOX-1 to restore apoptosis in esophageal cancer cells. We found that: (a) 15-LOX-1 was down-regulated in human esophageal carcinomas; (b) NSAIDs induced 15-LOX-1 expression during apoptosis in esophageal cancer cells; and (c) 15-LOX-1 inhibition suppressed NSAID-induced apoptosis, which was restored by 13-S-hydroxyoctadecadienoic acid but not by its parent compound, linoleic acid. These findings demonstrate that 15-LOX-1 is down-regulated in human esophageal carcinomas and that NSAIDs induce apoptosis in esophageal cancer cells via up-regulation of 15-LOX-1. They also support the concept that the loss of the proapoptotic role of 15-LOX-1 in epithelial cancers is not limited to human colorectal cancers.

Regulation of the cycling of timeless (tim) RNA

Circadian rhythms in Drosophila depend upon expression of the timeless (tim) and period (per) genes, which encode interacting components of the endogenous clock. These two clock genes show a robust circadian oscillation in transcription rate as well as RNA and protein levels. Transcriptional activation of both genes requires the basic helix-loop-helix (bHLH) PAS transcription factors dCLOCK (dCLK) and CYCLE (CYC), which bind E-box elements. We investigated the role of E-box elements in regulating behavioral rhythmicity and tim gene expression. We show that mutation of the upstream E-box in the tim gene prevents the rescue by tim cDNA sequences of the arrhythmic tim(01) phenotype. RNA encoded by this mutated tim transgene fails to cycle and is expressed at low levels. While a tim transgene carrying a wild-type E-box restores behavioral rhythms, tim RNA levels are intermediate to those of the mutant E-box transgenic lines and wild type, and do not display high amplitude cycling. On the other hand, high-amplitude RNA cycling was consistently obtained with a tim transgene that contains genomic, rather than cDNA, sequences. To identify additional sequences that may be required for tim cycling, we investigated the role of an E-box in the first intron of the tim gene through cell culture experiments. In these experiments, the presence of this intron did not have any effect on the activation of tim transcription by dCLK/CYC. As the upstream E-box was implicated in activation by dCLK/CYC in cell culture, we assayed sequences containing this E-box for association with proteins in fly head extracts. These studies provide the first biochemical evidence for an in vivo complex containing dCLK and CYC that binds the tim upstream sequence and is detected at all times of day. Together, these data highlight molecular mechanisms that are critical for behavioral rhythms.