Developmental changes in dopamine modulation of the heart in the isopod crustacean Ligia exotica: reversal of chronotropic effect

Developmental changes in dopamine modulation of the heart were examined in the isopod crustacean Ligia exotica. The Ligia cardiac pacemaker is transferred from the myocardium to the cardiac ganglion during juvenile development and the heartbeat changes from myogenic to neurogenic. In the myogenic heart of early juveniles, dopamine affected the myocardium and caused a decrease in the frequency and an increase in the duration of the myocardial action potential, resulting in negative chronotropic (decrease in beat frequency) and positive inotropic (increase in contractile force) effects on the heart. Contrastingly, in the heart of immature adults just after juvenile development, dopamine caused effects of adult type, positive chronotropic and positive inotropic effects on the heart affecting the cardiac ganglion and myocardium. During the middle and late juvenile stages, dopamine caused individually a negative or a positive chronotropic effect on the heart. These results suggest that the chronotropic effect of dopamine on the Ligia heart is reversed from negative to positive in association with the cardiac pacemaker transfer from the myocardium to the cardiac ganglion during juvenile development.

Frequent loss of RUNX3 gene expression in remnant stomach cancer and adjacent mucosa with special reference to topography

Our previous studies suggest that a lack of RUNX3 function is causally related to the genesis and progression of human gastric cancer. This study was conducted to determine whether alteration of RUNX3 gene expression could be detected in the normal-looking gastric remnant mucosa, and to ascertain any difference in the potential of gastric carcinogenesis between the anastomotic site and other areas in the remnant stomach after distal gastrectomy for peptic ulcer (RB group) or gastric cancer (RM group), by analysing RUNX3 expression with special reference to topography. A total of 89 patients underwent distal gastrectomy for gastric cancer from the intact stomach (GCI group) and 58 patients underwent resection of the remnant stomach for gastric cancer (RB group: 34 cases, RM group: 24 cases). We detected RUNX3 and gene promoter methylation by in situ hybridisation, quantitative reverse transcriptase-polymerase chain reaction (RT-PCR), and methylation-specific PCR. The interval between the initial surgery and surgery for remnant gastric cancer (interval time) was 10.4 years in the RM group, and 27.5 years in the RB group. Cancers in the RB group were significantly more predominant in the anastomosis area (P<0.05). Within the tumour, downregulation of RUNX3 expression ranged from 74.7 to 85.7% in the three groups. The rate of downregulation of RUNX3 of adjacent mucosa was 39.2% (11 in 28 cases) in RB and 47.6% (10 in 21 cases) in RM, which are significantly higher than that of the GCI group (19.5%, 17 in 87 cases). In noncancerous mucosa of the remnant stomach in the RB group, RUNX3 expression decreased more near the anastomosis area. In the RM group, however, there were no significant differences in RUNX3 expression by sampling location. Based on RUNX3 downregulation and clinical features, residual stomach mucosa of the RM group would have a higher potential of gastric carcinogenesis compared to the RB or GCI group. Gastric stump mucosa of the RB group has higher potential especially than other areas of residual stomach mucosa. Measurement of RUNX3 expression and detection of RUNX3 methylation in remnant gastric mucosa may estimate the forward risk of carcinogenesis in the remnant stomach.

Rice plant development: from zygote to spikelet

Rice is becoming a model plant in monocotyledons and a model cereal crop. For better understanding of the rice plant, it is essential to elucidate the developmental programs of the life cycle. To date, several attempts have been made in rice to categorize the developmental processes of some organs into substages. These studies are based exclusively on the morphological and anatomical viewpoints. Recent advancement in genetics and molecular biology has given us new aspects of developmental processes. In this review, we first describe the phasic development of the rice plant, and then describe in detail the developmental courses of major organs, leaf, root and spikelet, and specific organs/tissues. Also, for the facility of future studies, we propose a staging system for each organ.

Early detection of cardiac involvement in patients with sarcoidosis by a non-invasive method with ultrasonic tissue characterisation

OBJECTIVES

To clarify the value of cycle dependent variation of myocardial integrated backscatter (CV-IB) analysis, which non-invasively measures acoustic properties of the myocardium, for early detection of cardiac involvement in patients with sarcoidosis.

METHODS

The study population consisted of 22 consecutive patients with biopsy proven sarcoidosis who did not have any abnormal findings on conventional two dimensional echocardiogram. Cardiac sarcoidosis was diagnosed by radionuclide testing including thallium-201 scintigraphy, gallium-67 scintigraphy, and cardiac fluorine-18-deoxyglucose positron emission tomography. The magnitude and delay of the CV-IB were analysed in the basal mid septum and the basal mid posterior wall of the left ventricle of all patients.

RESULTS

The patients were divided into two groups: 8 patients with cardiac involvement and 14 patients without cardiac involvement. In the basal septum, a major reduction in the magnitude (mean (SD) 1.8 (4.4) v 6.6 (1.3), p = 0.012) and an increase in the time delay (1.3 (0.5) v 1.0 (0.1), p = 0.038) of CV-IB were observed in patients with cardiac sarcoidosis even in the absence of two dimensional echocardiographic abnormalities. The sensitivity for detecting cardiac involvement was such that the magnitude of CV-IB in the basal septum discriminated 75% of patients with cardiac sarcoidosis from those with non-cardiac sarcoidosis, whereas two dimensional echocardiographic parameters did not discriminate between these two groups.

CONCLUSIONS

The CV-IB is decreased in the basal septum in patients with cardiac sarcoidosis even in the absence of two dimensional echocardiographic abnormalities. Analysis of CV-IB may be a useful method to detect early myocardial involvement in patients with sarcoidosis.

Differential gene expression profiles of radioresistant oesophageal cancer cell lines established by continuous fractionated irradiation

Radiation therapy is a powerful tool for the treatment of oesophageal cancer. We established radioresistant cell lines by applying fractionated irradiation in order to identify differentially expressed genes between parent and radioresistant cells. Six oesophageal cancer cell lines (TE-2, TE-5, TE-9, TE-13, KYSE170, and KYSE180) were treated with continuous 2 Gy fractionated irradiation (total dose 60 Gy). We compared expression profiles of each parent and radioresistant lines on a cDNA microarray consisting of 21168 genes. In the fractionated irradiation trial, four radioresistant sublines (TE-2R, TE-9R, TE-13R, KYSE170R) were established successfully, and we identified 19 upregulated and 28 downregulated genes common to radioresistant sublines. Upregulated genes were associated with apotosis and inflammatory response (BIRC2 and COX-2), DNA metabolism (CD73), and cell growth (PLAU). Downregulated genes were associated with apoptosis (CASP6), cell adhesion (CDH1 and CDH3), transcription (MLL3), and cell cycle (CDK6). Some of these genes were known to be associated with radiation response, such as COX-2, but others were novel. Reverse transcription–polymerase chain reaction confirmed that genes selected by cDNA microarray were overexpressed in clinical specimens of radioresistant cases. Global gene analysis of radioresistant sublines may provide new insight into mechanisms of radioresistance and effective radiation therapy.

Ileal mucosa-associated lymphoid tissue lymphoma showing several ulcer scars detected using double-balloon endoscopy

A 72-year-old man was admitted to our hospital to undergo a novel small-intestinal endoscopic procedure. He had had occasional episodes of hematochezia over a 2-year period, during which he had been hospitalized twice previously. However, numerous investigations, including hematological and biochemical studies, gastroscopy, colonoscopy, computed tomography, scintigraphy, and angiography had failed to detect the source of bleeding in the gastrointestinal tract. On this admission, double-balloon enteroscopy was performed and revealed several ulcer scars with localized dilation of the ileum. Histopathological examination of the biopsy specimens revealed no abnormal findings. Partial resection of the ileum was performed to prevent further gastrointestinal bleeding, and histopathological examination of the resected specimen revealed aggregation of atypical lymphocytes, predominantly in the muscularis propria layer. Immunohistochemical examination demonstrated that the tumor cells were positive for CD20 and BCL2, but negative for UCHL1. Based on these findings, the lesion was diagnosed as a marginal-zone B-cell lymphoma of mucosa-associated lymphoid tissue. Eighteen months after surgery, the patient was still in complete remission.

Coronary risk factors in Kawasaki disease treated with additional gammaglobulin

AIMS

To assess the hypothesis that an additional intravenous gammaglobulin (IVGG) infusion, if administered early, may prevent coronary artery lesions (CAL) in patients with Kawasaki disease (KD) who do not respond to initial IVGG therapy.

METHODS

Forty four KD patients (17 with CAL and 27 without CAL), treated with additional IVGG because of persistent or recrudescent fever after initial IVGG therapy, were studied. Main outcome measures were the presence of CAL by echocardiography and the number of febrile days before and after start of additional IVGG infusion (pre- and post-additional IVGG).

RESULTS

In univariate analyses, risk factors for CAL were the number of febrile days pre-additional IVGG, the number of febrile days post-additional IVGG, the number of days that initial IVGG was divided over, the white blood cell count pre- and post-additional IVGG, and the C reactive protein concentration pre-additional IVGG. In a multivariate analysis, the only independent risk factor was the number of febrile days pre-additional IVGG (> or =10 days; odds ratio 7.86; 95% CI 1.44 to 42.8; p = 0.02).

CONCLUSIONS

Among KD patients with persistent or recrudescent fever after initial IVGG therapy, administration of additional IVGG before the first 10 febrile days was associated with a decreased prevalence of CAL, when compared with the prevalence in those who were retreated later. An additional IVGG infusion, if administered early, may prevent CAL in initial IVGG non-responders.

Overexpression of dopa decarboxylase in peritoneal dissemination of gastric cancer and its potential as a novel marker for the detection of peritoneal micrometastases with real-time RT-PCR

We previously performed a global analysis of the gene expression of gastric cancer cell lines established from metastases to the peritoneal cavity with the cDNA microarray method, which made it possible to analyse the expression of approximately 21 168 genes for the identification of novel markers for the detection of micrometastases in the peritoneal cavity. One of the upregulated genes is dopa decarboxylase (DDC), which is responsible for the synthesis of the key neurotransmitters dopamine and serotonine. We have examined its potential as a novel marker for the detection of peritoneal micrometastases of gastric cancer.

DDC mRNA in the peritoneal wash from 112 gastric cancer patients was quantified for comparison of carcinoembryonic antigen (CEA) mRNA by means of real-time reverse transcriptase–polymerase chain reaction (RT–PCR) with a fluorescently labelled probe to predict peritoneal recurrence. The quantity of DDC and CEA correlated with wall penetration. Real-time RT–PCR could quantitate 10–10⁶ DDC-expressing gastric cancer cells per 10⁷ mesothelial cells. The cutoff value was set at the upper limit of the quantitative value for noncancer patients, and those above this cutoff value constituted the micrometastasis (MM+) group. Of 15 cases with peritoneal dissemination, 13 were MM+DDC (87% sensitivity), and one of 48 t1 cases was MM+ (98% specificity). DDC levels in peritoneal washes from patients with synchronous peritoneal metastases were more than 50 times higher than in those from patients without metastasis (P<0.01). For 15 cases of peritoneal dissemination (seven cases were cytologically positive), DDC was positive in 13 cases (87% sensitivity), but CEA failed to detect micrometastases in four cases (73% sensitivity), indicating that DDC is in some cases superior to CEA for the detection of peritoneal micrometastases of gastric cancer in terms of sensitivity as well as specificity, especially for poorly differentiated adenocarcinomas. A combination of CEA and DDC improved the accuracy of diagnosis up to 94%.

These results suggest that DDC is potentially a novel marker for peritoneal dissemination of gastric cancer and that quantitative RT–PCR of DDC is reliable and efficient for the selection of patients for adjuvant intraperitoneal chemotherapy to prevent peritoneal recurrence.

Dual Effects of Dopamine on the Adult Heart of the Isopod Crustacean Ligia exotica

In the adult heart of the isopod crustacean Ligia exotica, the cardiac ganglion acts as the primary pacemaker with the myocardium having a latent pacemaker property. We show several lines of evidence that dopamine modulates the heartbeat of adult L. exotica affecting both pacemaker sites in the heart. Dopamine caused positive chronotropic (frequency increase) and inotropic (amplitude increase) effects on the heartbeat in a concentration dependent manner. The time courses of these effects were considerably different and the inotropic effect appeared later and lasted longer than the chronotropic effect. Dopamine rapidly increased the frequency of the bursting activity in the cardiac ganglion neurons and each impulse burst of the cardiac ganglion was always followed by a heartbeat. Moreover, dopamine slowly increased the amplitude and duration of the action potential plateau (plateau potential) of the myocardium. When the myocardial pacemaker activity was induced by application of tetrodotoxin, which suppresses cardiac ganglion activity, dopamine slowly increased the amplitude and duration of the myocardial plateau potential while decreasing its frequency. These results suggest that dopamine modulates the heartbeat in adult L. exotica producing a dual effect on the two pacemaker sites in the heart, the cardiac ganglion and myocardium.

Cloning and characterization of a novel radish protein kinase which is homologous to fungal cot-I like and animal Ndr protein kinases

According to the similarity of the amino acid sequences in their catalytic domains, eukaryotic protein kinases have been classified into the five main groups: 'AGC', 'CaMK', 'CMGC', 'PTK' and 'other'. The AGC group, represented by the cyclic nucleotide-dependent kinases (PKA and PKG), the calcium-phospholipid-dependent kinases (PKC) and the ribosomal S6 protein kinases, are poorly characterized in plants except for a few cases. In this study, in order to gain a better understanding of plant protein kinases in the AGC group, three cDNAs encoding novel protein kinases, RsNdr1 and RsNdr2a/b, were cloned from radish and characterized by molecular and biochemical methods. The deduced amino acid sequences of RsNdr1 and RsNdr2a/b contained all 12 conserved catalytic subdomains which are characteristic of the eukaryotic Ser/Thr protein kinases. A cell lysate from E. coli overexpressing RsNdr1 fusion protein had protein kinase activity toward a conventional protein substrate (myelin basic protein), whereas that from E. coli harboring a fusion plasmid encoding kinase-dead RsNdr1 or RsNdr2 did not show any protein kinase activity. A phylogenetic tree for 17 protein kinases from various organisms showed that the RsNdrs are more closely related to the protein kinases in a particular subgroup of the 'AGC' (fungal cot1-like and animal Ndr kinases) than to the authentic 'AGC' protein kinases, such as PKA, PKC or ribosomal S6 kinase.

Intravascular naked DNA vaccine encoding glycoprotein B induces protective humoral and cellular immunity against herpes simplex virus type 1 infection in mice

Naked plasmid DNA (pDNA) vaccine expressing herpes simplex virus type 1 (HSV-1) glycoprotein B (gB) was tested for protective activity against acute HSV-1 infection in mice. The pDNA was intravenously injected into Balb/c mice via their tail vein under high pressure, and the vaccination was performed two times at an interval of 7 days. The gB gene vaccination significantly protected the mice from subsequent intraperitoneal challenge with a lethal dose of HSV-1, which killed all the animals given control plasmid or saline. The protective activity was correlated with the dose of the plasmid inoculated, the survival rate reaching 83% in mice vaccinated with 5 microg of pDNA. The vaccinated mice were also protected from latent HSV infection. The immunized mice showed significant elevation in neutralizing antibody against HSV-1 as well as serum levels of interleukin-12 (IL-12) and interferon-gamma (IFN-gamma). When mice were immunized with 5 microg of an Epstein-Barr virus (EBV)-based plasmid vector harboring the gB, the cytotoxic T lymphocytes (CTLs) activity and proliferative response for HSV-1 were also induced. The results strongly suggest that intravenous immunization of naked pDNA may induce humoral and cellular immune responses against the virus, leading to a significant prophylactic outcome against HSV-1 infection in mice.

Somatic hybrids between Arabidopsis thaliana and cytoplasmic male-sterile radish (Raphanus sativus)

Somatic hybrids were produced by protoplast fusion between Arabidopsis thaliana ecotype Columbia and a male-sterile radish line MS-Gensuke ( Raphanus sativus) with the Ogura cytoplasm. Forty-one shoots were differentiated from the regenerated calli and established as shoot cultures in vitro. About 20 of these shoots were judged to be hybrids based on growth characteristics and morphology. Molecular analyses of 11 shoots were performed, confirming the hybrid features. Of these 11 shoots, eight were established as rooted plants in the greenhouse. Polymerase chain reaction and randomly amplified polymorphic DNA analyses of the nuclear genomes of all analyzed shoots and plants confirmed that they contained hybrid DNA patterns. Their chromosome numbers also supported the hybrid nature of the plants. Investigations of the organelles in the hybrids revealed that the chloroplast (cp) genome was exclusively represented by radish cpDNA, while the mitochondrial DNA configuration showed a combination of both parental genomes as well as fragments unique to the hybrids. Hybrid plants that flowered were male-sterile independent of the presence of the Ogura CMS-gene orf138.

Aminergic modulation of the myogenic heart in the branchiopod crustacean Triops longicaudatus

Although crustaceans typically have a neurogenic heart, the primitive crustacean Triops longicaudatus has a myogenic heart with the heartbeat arising from the endogenous rhythmic activity of the myocardium. In the present investigation, the effects of six biogenic amines, epinephrine, norepinephrine, dopamine, octopamine, serotonin and histamine, on the myogenic heart of T. longicaudatus were examined. Epinephrine, norepinephrine, dopamine and octopamine accelerated the heartbeat, increasing both the frequency and amplitude of the action potential of the myocardium in a concentration dependent manner. The ability of epinephrine and norepinephrine to produce the acceleratory effects was more potent than that of dopamine and octopamine; the threshold concentrations of epinephrine and norepinephrine were approximately 10(-10) M and those of dopamine and octopamine approximately 10(-7) M. Serotonin weakly inhibited the heartbeat, decreasing both the frequency and amplitude of the myocardial action potential in a concentration dependent manner with a threshold concentration of approximately 10(-6) M. Histamine exhibited no effect on the heartbeat. The results provide the first evidence for direct effects of amines on the crustacean myocardium and suggest neurohormonal regulation of the myogenic heart in T. longicaudatus.

Feasibility study using a new small electronic pancreatoscope: description of findings in chronic pancreatitis

BACKGROUND AND STUDY AIMS

Numerous images characteristic of chronic pancreatitis have been obtained with fiberoptic peroral pancreatoscopy systems. However, the resolution of these images is inferior to that obtained with peroral electronic pancreatoscopy (PEPS). Clearer images of the pancreatic duct with chronic pancreatitis have now been documented, in some cases using PEPS alone. The significance of this finding is reported here.

PATIENTS AND METHODS

A total of 42 PEPS procedures were carried out in 36 patients with chronic pancreatitis, without sphincterotomy or balloon dilation of the papilla of Vater. Using endoscopic retrograde pancreatography, the patients were classified as having equivocal (n=5), mild (n=5), moderate (n=15), or marked (n=11) degrees of chronic pancreatitis. The insertion rate with PEPS was 90 % (38 of 42 procedures), and it was ultimately possible to examine five, three, 13, and 11 patients in each group, respectively.

RESULTS

Images of turbid pancreatic juice, protein plugs of various shapes, pancreatic calculi, indistinct vascular markings, whitish mucosa, local redness, scattered redness, disappearance of the fold, deformation of the fold, irregularly dilated lumen, and stenosis were found to be characteristic of chronic pancreatitis. These images were obtained using PEPS.

CONCLUSIONS

PEPS proved to be a feasible new technique for diagnosing chronic pancreatitis, and it was able to detect abnormal findings more clearly than other imaging methods.

Regeneration of hypogastric nerve using a polyglycolic acid (PGA)-collagen nerve conduit filled with collagen sponge proved electrophysiologically in a canine model

The hypogastric nerve (HGN) is a sympathetic nerve in the peritoneal cavity and controls urinary and seminal functions. In this study, the regeneration of HGN was determined by using a new type of an artificial nerve conduit, polyglycolic acid (PGA)-collagen nerve conduit filled with collagen sponge in two dogs. A PGA-collagen nerve conduit (diameter=2 mm) was interposed in a 10 mm gap of the right HGN. The regeneration of the HGN was evaluated electrophysiologically 8 months after the operation. The intraluminal pressure of spermatic duct and the bladder neck were elevated 80 mmHg and 25 mmHg respectively by the stimulation across the regenerated HGN. The prostate contraction was also elicited. The responses diminished after the excision of the regenerated portion of HGN. These results proved the regeneration of HGN and this nerve conduit will be great help for patients who suffer from urinary and seminal disturbances.

Multiple origins of cultivated radishes as evidenced by a comparison of the structural variations in mitochondrial DNA of Raphanus

Configurations of mitochondrial coxI and orfB gene regions were analysed by polymerase chain reaction (PCR) in three wild and one cultivated species of Raphanus. A total of 207 individual plants from 60 accessions were used. PCR with five combinations of primers identified five different amplification patterns both in wild and cultivated radishes. While the mitochondrial DNA (mtDNA) type of Ogura male-sterile cytoplasm was distinguishable from the normal type, the mtDNAs of normal radishes were further classified into four types. The variations were common to wild and cultivated radishes, although contrasting features were found depending on the region of cultivation. These results provide evidence that cultivated radishes have multiple origins from various wild plants of Raphanus.

Assessment of myocardial perfusion abnormalities by intravenous myocardial contrast echocardiography with harmonic power Doppler imaging: comparison with positron emission tomography

BACKGROUND

Intravenous myocardial contrast echocardiography with harmonic power Doppler imaging (HPDI) enables assessment of myocardial perfusion. Its accuracy in comparison with positron emission tomography (PET), which is one of the most reliable clinical gold standards for myocardial perfusion, remains to be determined.

OBJECTIVE

To assess the ability of HPDI to identify myocardial perfusion abnormalities, using PET as a gold standard.

METHODS

23 patients with myocardial infarction underwent HPDI. Images were obtained from the apical two and four chamber views at pulsing intervals of one to eight cardiac cycles with continuous infusion of Levovist (Schering, Germany). PET was done within two weeks of HPDI. The left ventricle was divided into 12 segments and myocardial opacification by HPDI and uptake of NH(3) by PET in each segment was graded as normal, mildly reduced, or severely reduced.

RESULTS

Of the 276 segments examined, adequate image quality was obtained in 226 (82%) by HPDI; 50 segments were excluded because of inadequate image quality. There were more exclusions in the basal segments than in the mid or apical segments (p < 0.0001). Of the 226 segments analysed, overall concordance between HPDI and PET was 82% (chi = 0.70). In the apex, more segments were overestimated by HPDI than were underestimated (chi(2) = 6.25, p = 0.012).

CONCLUSIONS

HPDI and PET gave similar results in the assessment of myocardial perfusion abnormalities. However, poor image quality in the basal segments and overestimation of perfusion in the apical segments are current limitations of HPDI.

Congenital long QT syndrome and 2:1 atrioventricular block with a mutation of the SCN5A gene

Infants with congenital long QT syndrome (LQTS) and 2:1 atrioventricular block (AVB) have been recognized as a clinical subset of children with LQTS. However, the genotype of this disorder is not well-known. We report an infant with LQTS and 2:1 AVB with a mutation of the SCN5A gene (LQT3). In some patients with LQTS and 2:1 AVB, the disorder may be due to mutation of the SCN5A gene (LQT3).

Assessment of myocardial viability using coronary zero flow pressure after successful angioplasty in patients with acute anterior myocardial infarction

OBJECTIVES

To investigate the relation between coronary flow reserve (CFR), coronary zero flow pressure (Pzf), and residual myocardial viability in patients with acute myocardial infarction.

DESIGNS

Prospective study.

SETTING

Primary care hospital.

PATIENTS

27 consecutive patients with acute anterior myocardial infarction.

MAIN OUTCOME MEASURES

F-fluorodeoxyglucose (FDG) positron emission tomography (PET) was used in 27 patients who underwent successful intervention within 12 hours of onset of a first acute anterior myocardial infarction. Within three days before discharge they had < 25% stenosis in the culprit lesion as determined by angiography 24 (3) days after acute myocardial infarction. Pzf and the slope index of the flow-pressure relation (SIFP) were calculated from the simultaneously recorded aortic pressure and coronary flow velocity signals at peak hyperaemia.%FDG was quantified by comparing FDG uptake in the infarct myocardium with FDG uptake in the normal myocardium.

RESULTS

There was a correlation between %FDG and CFR, where y = -1.477x + 62.517, r = -0.072 (NS). There was also a correlation between %FDG and SIFP, where y = -0.975x + 60.542, r = -0.045 (NS), and a significant correlation between %FDG and Pzf, where y = -0.98x + 85.108, r = -0.696 (p < 0.001).

CONCLUSIONS

CFR does not correlate with FDG-PET at the time of postreperfusion evaluation of residual myocardial viability. The parameter that correlates best with residual myocardial viability is Pzf and this may be a useful index for predicting patient prognosis.

Cell death processes during expression of hybrid lethality in interspecific F1 hybrid between Nicotiana gossei Domin and Nicotiana tabacum

Hybrid lethality, a type of reproductive isolation, is a genetically controlled event appearing at the seedling stage in interspecific hybrids. We characterized the lethality of F(1) hybrid seedlings from Nicotiana gossei Domin and Nicotiana tabacum cv Bright-Yellow 4 using a number of traits including growth rate, microscopic features of tissues and cells, ion leakage, DNA degradation, reactive oxygen intermediates including superoxide radical (O(2)(-)) and hydrogen peroxide (H(2)O(2)), and expression of stress response marker genes. Lethal symptoms appeared at 4 d after germination in the basal hypocotyl and extended toward both the hypocotyl and root of the plants grown at 26 degrees C. Microscopic analysis revealed a prompt lysis of cell components during cell death. Membrane disruption and DNA degradation were found in the advanced stage of the lethality. The death of mesophyll cells in the cotyledon was initiated by the vascular bundle, suggesting that a putative factor inducing cell death diffused into surrounding cells from the vascular tissue. In contrast, these symptoms were not observed in the plants grown at 37 degrees C. Seedlings grown at 26 degrees C generated larger amounts of reactive oxygen intermediate in the hypocotyl than those grown at 37 degrees C. A number of stress response marker genes were expressed at 26 degrees C but not at 37 degrees C. We proposed that a putative death factor moving systemically through the vascular system induced a prompt and successive lysis of the cytoplasm of cells and that massive cell death eventually led to the loss of the hybrid plant.

Differential gene expression profiles of gastric cancer cells established from primary tumour and malignant ascites

Advanced gastric cancer is often accompanied by metastasis to the peritoneum, resulting in a high mortality rate. Mechanisms involved in gastric cancer metastasis have not been fully clarified because metastasis involves multiple steps and requires a combination of altered expressions of many different genes. Thus, independent analysis of any single gene would be insufficient to understand all of the aspects of gastric cancer peritoneal dissemination. In this study, we performed a global analysis of the differential gene expression of a gastric cancer cell line established from a primary main tumour (SNU-1) and of other cell lines established from the metastasis to the peritoneal cavity (SNU-5, SNU-16, SNU-620, KATO-III and GT3TKB). The application of a high-density cDNA microarray method made it possible to analyse the expression of approximately 21 168 genes. Our examinations of SNU-5, SNU-16, SNU-620, KATO-III and GT3TKB showed that 24 genes were up-regulated and 17 genes down-regulated besides expression sequence tags. The analysis revealed the following altered expression such as: (a) up-regulation of CD44 (cell adhesion), keratins 7, 8, and 14 (epitherial marker), aldehyde dehydrogenase (drug metabolism), CD9 and IP3 receptor type3 (signal transduction); (b) down-regulation of IL2 receptor gamma, IL4-Stat (immune response), p27 (cell cycle) and integrin beta4 (adhesion) in gastric cancer cells from malignant ascites. We then analysed eight gastric cancer cell lines with Northern blot and observed preferential up-regulation and down-regulation of these selected genes in cells prone to peritoneal dissemination. Reverse transcriptase-polymerase chain reaction confirmed that several genes selected by DNA microarray were also overexpressed in clinical samples of malignant ascites. It is therefore considered that these genes may be related to the peritoneal dissemination of gastric cancers. The results of this global gene expression analysis of gastric cancer cells with peritoneal dissemination, promise to provide a new insight into the study of human gastric cancer peritoneal dissemination.

Are both PIVKA-II and alpha-fetoprotein necessary in follow-up management after hepatic resection for hepatocellular carcinoma?

BACKGROUND/AIMS

The aim of this study was to clarify the need for measuring of PIVKA-II (protein induced by vitamin K absence or antagonist-II) and alpha-fetoprotein as the prognostic indicator for patients after hepatic resection for hepatocellular carcinoma, and as the monitoring modality for early detection of recurrence after hepatic resection.

METHODOLOGY

One hundred and thirty-one patients who underwent planned liver resections for hepatocellular carcinoma were studied.

RESULTS

The survival rates in patients positive for preoperative tumor markers were significantly lower than in those in the negative patients. The first modality leading to the diagnosis of recurrence was measurement of alpha-fetoprotein and/or PIVKA-II in 25 cases (55.6%). Almost all patients (96.6%) with positive preoperative alpha-fetoprotein and recurrence had elevated alpha-fetoprotein again when recurrence was found.

CONCLUSIONS

Preoperative PIVKA-II and/or alpha-fetoprotein levels can predict postoperative prognosis. Measurement of these markers is useful in monitoring recurrence. For following up patients with alpha-fetoprotein-producing tumors, alpha-fetoprotein monitoring only is sufficient to detect recurrence.

Cardiac pacemaker mechanisms in the ostracod crustacean Vargula hilgendorfii

The heart of the ostracod crustacean Vargula hilgendorfii has a single intrinsic neuron that morphologically appears to innervate the myocardium. We, therefore, examined the heart activity electrophysiologically to determine whether the heartbeat is neurogenic. Each heartbeat is associated with a myocardial action potential composed of a spike potential followed by a plateau potential. The frequency of the action potential is not stable but changes successively over a wide range. The action potential is not preceded by a pacemaker potential and has an inflection in its rising phase. The myocardial cells couple electrically and fire almost simultaneously. The frequency of the action potential was unchanged by injection of depolarizing or hyperpolarizing current into the myocardium. However, slow oscillatory potentials appeared during the depolarization and its frequency was higher with increasing current intensity. Application of 1-microM tetrodotoxin (TTX) depolarized the myocardial membrane and completely prevented the action potential. During this depolarization, slow oscillatory potentials often appeared spontaneously. These results suggest that, although the myocardium has a property of conditional oscillator, the heartbeat is driven by the single cell cardiac ganglion that has both pacemaker and motor functions.