Molecular analysis of hormone-regulated petal regeneration in Petunia

The petal is an important floral organ of higher plants. To study the mechanism of petal development, the in vitro regeneration system of petals was established in Petunia. High-frequency induction of petals occurred directly from explants on the media containing the combination of N6-benzyladenine (6-BA) and indole-3-acetic acid (IAA). Expression analysis of genes involved in flower development indicated that these genes were classified into three types. ABERRANT LEAF AND FLOWER (ALF) gene was induced during petal regeneration. Whereas, B-class and E-class genes, and genes involved in cell division were constitutively upregulated. In contrast, C-class and D-class genes were not expressed in explants and regenerated tissues. Further, in situ hybridization analysis showed that both ALF and GREEN PETAL (GP) expression were spatially regulated. The results suggest that differential regulation of gene expression occurs in the presence of hormones during petal regeneration, and hormone-regulated gene expression might be required for petal regeneration. This study provides the preliminary information to understand the mechanism of petal regeneration.

Allelic imbalance on chromosomes 3p, 9p and 17p in malignant progression of laryngeal mucosa

Objectives/hypothesis:

To evaluate the character and significance of microsatellite deoxyribonucleic acid allelic imbalance in laryngeal squamous cell carcinogenesis.

Methods:

We investigated the frequency of expression and clinical relationships of loss of heterozygosity and microsatellite instability in 49 laryngeal premalignant and malignant lesions. Allelic imbalance was analysed using six polymorphic markers (D3S1234, D9S171, D9S1748, D9S162, D9SINFA and D17S796), via polymerase chain reaction – single sequence length polymorphism – silver staining.

Results:

Allelic loss was seen in 3.7 per cent of the six markers in hyperplastic lesions, 10.81 per cent in mild dysplasia, 26.03 per cent in moderate to severe dysplasia, and 38.67 per cent in laryngeal squamous cell carcinoma. Significant associations were found between allelic loss and clinical pathological grades (χ2 = 17.686, p = 0.000). No statistically significant difference was found in the frequency of microsatellite instability (χ2 = 0.314, p > 0.05). In the early stages of neoplastic change, the incidence of microsatellite instability was higher than that of loss of heterozygosity.

Conclusions:

Allelic imbalance was associated with the carcinogenesis and progression of laryngeal squamous cell carcinoma. Microsatellite analysis might provide new approaches to early genetic detection for patients with premalignant laryngeal lesions.

Hormone-regulated inflorescence induction and TFL1 expression in Arabidopsis callus in vitro

To study hormone-regulated inflorescence development, we established the in vitro regeneration system of Arabidopsis inflorescences in the presence of cytokinin and auxin. Media containing a combination of thidiazuron (TDZ) and 2,4-dichlorophenoxyacetic acid (2,4-D) were used to induce callus formation. Higher frequencies of calli were obtained by using the inflorescence stems as explants. After transferring the calli to media containing a combination of zeatin and indole-3-acetic acid (IAA), the inflorescences were induced from the calli. The morphology of regenerated inflorescences was similar to that of inflorescences in plants; however, flowers of regenerated inflorescences often lacked a few floral organs. Furthermore, TFL1, a gene involved in floral transition in Arabidopsis, was activated during the inflorescence induction. Our results suggest that the TFL1 gene plays an important role in hormone-regulated inflorescence formation.

Magnetic-field-dependent carrier injection at La2/3Sr1/3MnO3/ and organic semiconductors interfaces

We have fabricated organic diodes utilizing several pi-conjugated organic semiconductors (OSEC) as spacer layers between La2/3Sr1/3MnO3 (LSMO) and various metallic electrodes, and measured their magnetoresistance (MR) and magnetoelectroluminescence (MEL) responses. The devices exhibit large negative high-field MR responses that resemble the MR response of the LSMO electrode, but amplified by approximately 3 orders in the resistance, and accompanied by a positive high-field MEL effect. These magnetic-field effects result from enhanced carrier injection at the LSMO-OSEC interface that is attributed to the anomalous field-dependent Fermi level shift in LSMO.

A simple and convenient route to prepare poly(vinylidene fluoride trifluoroethylene) copolymer nanowires and nanotubes

Poly(vinylidene fluoride trifluoroethylene) copolymer nanowires and nanotubes have been prepared for the first time via a high temperature (</=260 degrees C) vacuum infiltration method, which is a simple and convenient route for fabricating polymer nanowires and nanotubes when polymers, instead of monomers, are used as the starting materials.

Pistil induction by hormones from callus of Oryza sativa in vitro

This study describes the successful formation of floral organ pistil from the callus of pistil explants of Oryza sativa L. For induction of floral organs, different explants--including young embryo, lemma, palea and pistil--were used for callus induction with different combinations of N(6)-benzyladenine and 2,4-dichlorophenoxyacetic acid (2,4-D). High frequencies of callus formation from pistil and young embryo explants were achieved. Floral organs were induced after calli from pistils were transferred to medium containing both zeatin and 2,4-D. The morphological characteristics of the pistil-like organs are very similar to those formed in planta though with minor differences. Further histological study revealed that the in vitro pistil contains an ovule within its ovary. Furthermore, a pistil-specific gene, OsMADS3 used as a molecular marker for pistil identity, was expressed in the pistil-like organs as it was in pistils in the flower of the plant.

Beyond the locus control region: new light on beta-globin locus regulation

The locus control region (LCR) is a novel class of cis-acting regulatory sequences that enable high-level, tissue-specific, copy number-dependent, and chromosomal position-independent gene expression in transgenic mice. Recent studies on endogenous beta-globin locus and other loci have offered new insights either in support of or in contrast to our knowledge of the relationship between chromatin conformation and transcriptional regulation, the long-distance interaction between enhancers and promoters, and the developmental switching of multiple-gene loci. Our perceptions of the regulatory roles for LCR and elements beyond the LCR in beta-globin locus regulation have been challenged and demand re-evaluation. A sound elucidation of gene regulation mechanisms may rely on a fine understanding of functional interplay between cis-acting elements and trans-acting factors that participate in gene silencing and activation in their native genomic, cellular, and developmental state.

Differential expression of a novel colorectal cancer differentiation-related gene in colorectal cancer

AIM: To investigate SBA2 expression in CRC cell lines and surgical specimens of CRC and autologous healthy mucosa.

METHODS: Reverse transcription-polymerase chain reaction (RT-PCR) was used for relative quantification of SBA2 mRNA levels in 4 human CRC cell lines with different grades of differentiation and 30 clinical samples. Normalization of the results was achieved by simultaneous amplification of β-actin as an internal control.

RESULTS: In the exponential range of amplification, fairly good linearity demonstrated identical amplification efficiency for SBA2 and β-actin (82%). Markedly lower levels of SBA2 mRNA were detectable in tumors, as compared with the coupled normal counterparts (P < 0.01). SBA2 expression was significantly (0.01 < P < 0.05) correlated with the grade of differentiation in CRC, with relatively higher levels in well-differentiated samples and lower in poorly-differentiated cases. Of the 9 cases with lymph nodes affected, 78% (7/9) had reduced SBA2 mRNA expression in contrast to 24% (5/21) in non-metastasis samples (0.01 < P < 0.05).

CONCLUSION: SBA2 gene might be a promising novel biomarker of cell differentiation in colorectal cancer and its biological features need further studies.

[Expression of different receptors of the apoptosis inducing gene TRAIL in human ovarian tumors]

Reverse transcriptase polymerase chain reaction (RT-PCR) was applied to assay mRNA expression of TRAIl(the TNF related apoptosis inducing ligand) receptors (DR5, DcR1, and DcR2) in 3 cases of normal ovarian tissues, 6 cases of ovarian benign tumors, and 16 cases of ovarian cancers. Peripheral blood lymphocytes were used as a positive control. Positive expression of the DR5 and DcR1 were found in peripheral blood lymphocytes and 3 cases of normal ovaries. Positive expressions of the DR5 and DcR1 were 83.3%(5/6) in benign ovarian tumors and 68.8%(11/16) in ovarian cancers respectively. Positive expression of the DcR2 was only found in normal ovaries and benign tumors. These findings suggest that expression of different receptors may play an important role in the apoptosis regulation of ovarian tumors, especially DcR2.

[Measurements of proton response of two lithium fluoride detectors with different thicknesses]

OBJECTIVE

To study the response characteristics of LiF detectors to proton fluence rate and energy, and to observe the thickness effect of the detector.

METHOD

Protons were generated by an accelerator. Proton energy was changed in two ways, i.e. changing the accelerator energy directly, or using detector stacks to absorb the proton energy. The incident proton energy on each chip of detector stacks was calculated according to proton range in LiF.

RESULT

The response of the detector to proton fluence rate was almost constant; when proton energy was above 9 MeV, the response of the detector to proton energy was constant (less than 10% errors). When proton energy was below 9 MeV, the response reduced gradually with the decrease of proton energy. Thickness effect for LiF thicknesses of 0.4mm and 0.8mm was not obvious.

CONCLUSION

The homemade LiF detector is suitable for measurement of space radiation dose. When proton component (below 9 MeV) was abundant in radiation field, the decrease of the relative thermoluminescence efficiency should be taken into consideration.

[An analysis on thickness effect of lithium fluoride detector in proton measurement]

OBJECTIVE

To theoretically analyze the thickness effect of a LiF detector for proton measurement.

METHOD

Thickness effect of the detector was calculated by using the definition of the detector dose under ideal and reasonable hypothesis.

RESULT

The thickness effect of the detector was not obvious when protons could penetrate the detector: when proton energy was above 12 MeV, the thickness effect was obvious only on condition that the detector thickness approaches proton range, when proton energy was less than 12 MeV, the thickness effect was not obvious. The thickness effect of the detector was obvious, when protons could not penetrate the detector.

CONCLUSION

Thin detectors should be used in low energy proton measurements to avoid thickness effect of the detector.

Effects of mutations in the F361 to R364 region of topoisomerase I (Topo I), in the presence and absence of 9-aminocamptothecin, on the Topo I-DNA interaction

Steady-state levels and rates of DNA binding and release of wild-type and mutant topoisomerase I (Topo I) proteins were quantified by surface plasmon resonance analysis. The proteins were constructed and expressed as GST fusion proteins. The Topo I mutations analyzed were F361S, R362L and R364G, all altering a highly conserved region of wild-type eukaryotic Topo I. The R362L and R364G mutations resulted in much lower steady-state levels of DNA binding than wild-type. This was due to a large increase in the k(d). The F361S mutation increased the steady-state levels of the protein-DNA interaction by increasing the k(a) 2-fold, while having little effect on the k(d). The F361S mutation has been shown to confer resistance to camptothecin and its analogs. The camptothecin analog 9-aminocamptothecin decreased greatly the overall k(d) of the wild-type Topo I, but had little effect on the F361S mutant. Both the wild-type and the F361S mutant exhibited decreased steady-state levels in the presence of the drug, and this was attributable to decreased association.

A maize Myb homolog is encoded by a multicopy gene complex

The maize P gene encodes a Myb-homologous transcriptional regulator of flavonoid pigmentation in floral organs, and different P gene alleles condition precise tissue- and organ-specific pigmentation patterns. To determine the molecular basis for allele-specific expression patterns, we have isolated and compared two natural alleles of the P gene which differ in expression, structure and copy number. The P-rr allele is associated with pigmentation of most floral tissues and contains a single copy of the P gene. In contrast, the P-wr allele restricts pigmentation to a subset of floral tissues, and is composed of six gene copies arranged in a tandem head-to-tail array. Each of the six repeats contains a single P gene, including regulatory and coding sequences. Despite the six-fold tandem repetition of P-wr gene copies, P-wr mRNA levels in kernel pericarp are much reduced compared to mRNA levels from the single-copy P-rr gene. Moreover, the P-wr multicopy complex is hypermethylated relative to P-rr. Thus, maize P gene alleles may represent a natural system for studying the effects of methylation and gene copy number on tissue-specific gene expression. We discuss the possibility that somatic pairing of repeated gene copies may be involved in regulating gene expression.

High-performance liquid chromatographic quantitation of total and lactone 20(S)camptothecin in patients receiving oral 20(S)camptothecin

We have developed a sensitive high-performance liquid chromatography (HPLC) assay to quantitate total and lactone forms of 20(S)camptothecin (CPT) in human plasma. Lactone and total CPT were extracted using solid-phase extraction and liquid-liquid extraction, respectively. The extracted lactone samples could be stored without immediate HPLC analysis. The two forms of CPT were quantitated by reversed-phase HPLC with fluorescence detection. The extraction efficiencies were about 100% and 92% for the total and lactone forms, respectively. The lower limit of quantitation was 5.74 nM for the two forms. The method was reproducible with a mean interday and intraday variability of 6% for total CPT and 4% and 6%. respectively, for lactone CPT. The assay could effectively quantitate lactone and total CPT in patients receiving single dose and multiple doses of oral CPT.

The use of lipid-coated microbubbles as a delivery agent of 7beta-hydroxycholesterol in a radiofrequency lesion in the rat brain

OBJECTIVE

This laboratory has previously described the aggregation of intravenously administered lipid-coated microbubbles (LCM) around tumors and areas of injury. 7Beta-hydroxycholesterol has been used to inhibit astrocytic proliferation in nervous system injury models. The compound has been given by direct infusion, by epidural catheter, or in liposomes (delivered stereotactically to the injury site). In this article, we report the use of LCM to deliver 7beta-hydroxycholesterol to a radiofrequency injury site in the rat cerebrum.

METHODS

First, the ability of LCM to target the thermal lesion in the rat brain was characterized using a lipid-soluble fluorescent dye 3,3-dioctadecyloxacarbocyanine perchlorate. Then, the effectiveness of this delivery system in suppression of glial proliferation was measured by glial fibrillary acidic protein immunoreactivity.

RESULTS

Glial fibrillary acidic protein immunoreactivity was significantly reduced when 7beta-hydroxycholesterol was administered via LCM but not alone, suggesting that astrocytic proliferation would correspondingly be diminished.

CONCLUSION

LCM were assessed as a delivery vehicle for 7beta-hydroxycholesterol in a rat brain radiofrequency lesion and found to be efficient in reducing astrogliosis, as measured by glial fibrillary acidic protein immunoreactivity.

Mechanisms of resistance in a human cell line exposed to sequential topoisomerase poisoning

Camptothecins are a new class of anticancer drugs that target DNA topoisomerase I; current efforts are directed toward elucidating optimal combinations of these drugs with other antineoplastic agents. A rationale for the use of sequential therapy involving the combination of camptothecins with topoisomerase II-targeting drugs, such as etoposide, has arisen from observations of increased topoisomerase II protein levels in cell lines resistant to camptothecin. In an effort to understand potential mechanisms of resistance to this strategy, we developed a U-937 cell subline, denoted RERC, that is capable of surviving exposure to sequential topoisomerase poisoning. The RERC cells are 200-fold resistant to camptothecin, 8-fold resistant to etoposide, and 10-fold hypersensitive to cisplatin compared to the parental U-937 cells. Biochemical analyses indicate that the resistant phenotype involves alterations in both topoisomerase I and topoisomerase IIalpha. Topoisomerase I catalytic activity in the resistant cells is similar to that of the parental line but is resistant to camptothecin. Moreover, the resistant cells express a single mRNA species of topoisomerase I that codes for a mutation in codon 533. In addition, topoisomerase IIalpha protein levels are decreased 10-fold in the resistant line, coincident with a two-fold decrease in the expression of topoisomerase IIalpha mRNA. Collectively, these results indicate that resistance to sequential topoisomerase poisoning may involve a reduction in total cellular topoisomerase activity.

Involvement of amino acids 361 to 364 of human topoisomerase I in camptothecin resistance and enzyme catalysis

Camptothecins are antineoplastic drugs that specifically target the enzyme DNA topoisomerase I. Prior work has identified a human topoisomerase I mutation, F361S, that confers resistance to camptothecin. We now demonstrate that substitutions in the 361-364 region can alter DNA cleavage/ligation by the enzyme. The defective catalysis exhibited by certain mutants likely relates to an impaired interaction with DNA, since these enzymes are more sensitive to the inhibitory effects of DNA binding ligands. Moreover, studies with peptides and fusion proteins suggest that the 361-364 region may bind DNA directly. The finding that the 361-364 region is involved in both enzyme catalysis and camptothecin resistance suggests that this region is part of the active site of human topoisomerase I and that camptothecin may interact with the enzyme at this site.

The affinity of lipid-coated microbubbles for maturing brain injury sites

The availability of a vehicle to deliver lipid soluble agents to a brain injury site may be of potential value in management of brain injury. This work describes the aggregation of intravenously administered Lipid-Coated Microbubbles (LCM) in the injury site following an experimental radiofrequency rat brain lesion. The bubbles can be identified around the region of the injury after the lesion has matured at least 48 h. The greatest bubbles density is evident after the lesion has matured for 10 days. This bubble density, reflecting "affinity," decreases to a plateau level from the second to the third week after injury. In order to investigate the potential relationship of bubble influx to posttraumatic astrocytosis and to cell turnover in the region, we utilized dual-channel laser-scanning confocal microscopy to track both bubble influx into the region and concomitant Glial Fibrillary Acidic Protein (GFAP) expressing astroctyte cell distribution. Cell turnover was assayed in separate sections using immunohistochemical staining of Proliferating Cell Nuclear Antigen (PCNA). We suggest a relationship between the LCM affinity and reactive astrocytes, but found no affinity of LCM for cells which stained positive with PCNA.

Puqiedinone, a novel 5 alpha-cevanine alkaloid from the bulbs of Fritillaria puqiensis, an antitussive traditional Chinese medicine

A novel 5 alpha-cevanine alkaloid, puqiedinone [1], was isolated from the bulbs of Fritillaria puqiensis, a traditional Chinese medicine used widely for its antitussive and expectorant properties. The structure of 1 was assigned as (20R,22S,25R)-20-deoxy-5 alpha-cevanine-3 beta-ol-6-one based on spectral analysis and comparison with the structures of related known compounds. Puqietinone [2] was also identified from the same herbal plant and the structure was revised as (22R,25S)-N-methyl-22,26-epiminocholest-3 beta-ol-6-one based on spectroscopic and X-ray crystallographic methods.

Morphometric and electrical properties of reconstructed hippocampal CA3 neurons recorded in vivo

CA3 pyramidal neurons were stained with biocytin during intracellular recording in rat hippocampus in vivo and reconstructed using a computer-based system. The in vivo CA3 neurons were characterized primarily according to their proximity to the hilus and secondarily with respect to the septotemporal location. Neurons measured in CA3a (n = 4), in CA3b (n = 4), and in posterior/ventral locations (n = 3) had the greatest dendritic lengths (19.8, 19.1, and 26.8 mm on average, respectively). Cells closer to the hilus showed much shorter dendritic lengths, averaging 10.4 mm for CA3c neurons (n = 4) and 11.6 mm for zone 3 neurons (n = 2). Half of the cells showed more than one major apical dendrite, and dendritic trees were highly variable even within CA3 subregions. The mean electronic length for these cell groups averaged between 0.30 lambda (CA3c) and 0.45 lambda (posterior/ventral), assuming a constant specific-membrane resistivity of 60 K omega-cm2. These CA3 neurons form a database of reconstructed neurons for further morphometric and electrical modelling studies. The large degree of variability between individual CA3 neurons indicates that both dendritic and electrical properties should be specifically calculated for each cell rather than assuming a "typical" morphology.

Successful thrombolysis for prosthetic pulmonary valve obstruction

Thrombosis is a serious complication of prosthetic heart valve operations. In recent years, systemic thrombolysis has emerged as a suitable alternative to surgery. Experience with thrombosis of pulmonary prosthetic valves is very limited. We report a case of successful administration of intravenous streptokinase for thrombosis of a St. Jude Medical prosthetic valve 3 weeks after pulmonary valve replacement.

[Intrasplenic metastasis of malignant ovarian tumor: clinical analysis of 12 cases]

Intrasplenic metastasis of ovarian malignancies are uncommon. From 1986 to 1992 only 12 such cases were diagnosed, being 1.2% of the total number of patients with ovarian malignancies treated in tumor hospital during the same period. Of the 12 metastasis, 6 were poorly differentiated. Diagnosis was made through imaging techniques or surgery. The median interval from the diagnosis of the primary disease to intrasplenic involvement was 28 months. The metastatic lesions, presented themselves as single or multiple nodes within the cortex of the spleen. Clinical features were not remarkable. It was thought that the occurrence of intrasplenic involvement might be due to greater tumor bulk, poor differentiation and decreased host immuno-competence caused by chemotherapy. Most of the intrasplenic metastasis was found after liver metastasis or simultaneously with the latter. The main route of the tumor spread might be via blood vessels. Sole intrasplenic metastasis can be treated by surgery with a temporarily good result. Poor prognosis and high mortality characterize intrasplenic metastasis. The median survival was only 7 months.

Electrophysiologic effects of total flavones of Hippophae rhamnoides L on guinea pig papillary muscles and cultured rat myocardial cells

The effects of total flavones of Hippophae rhamnoides L (TFH) were evaluated using conventional microelectrode technic. After administration of TFH 100-200 mg.L-1, the action potential duration of 50% repolarization (APD50) was shortened both in cultured rat myocardial cells and in guinea pig papillary muscles. The slope of phase 4 of depolarization (SP4) in cultured rat myocardial cells was decreased and the contractile force (CF) in guinea pig papillary muscles was weakened. Arrhythmias evoked by strophantin G in guinea pig papillary muscles were suppressed by TFH 100 mg.L-1. These findings suggested that the influence of TFH on myocardial cells may be resulted mainly from its inhibition of Ca2+ influx and its interference with intracellular Ca2+ reservoir.