Modulatory effect of ginseng total saponin on dopamine release and tyrosine hydroxylase gene expression induced by nicotine in the rat

Several studies have demonstrated that behavioral activation induced by psychostimulants is prevented by ginseng total saponin (GTS), which has been known to act on the central dopaminergic system. In an attempt to investigate whether the effect of GTS is through its inhibitory action on the elevated dopaminergic transmission, we examined the effect of GTS on nicotine-induced dopamine (DA) release in the nucleus accumbens (NA) of freely moving rats using in vivo microdialysis. Systemic injection of nicotine (3 mg/kg; i.p.) produced a mild increase in extracellular DA of dialysates samples in the NA (132+/-13% over basal levels at the peak). GTS (100 mg/kg; i.p.) had no effect on resting levels of extracelluar DA. However, an increase in accumbens DA release produced by systemic nicotine was completely blocked by systemic pre-treatment with GTS (100 mg/kg; i.p.). In addition, the effect of GTS on nicotine-induced tyrosine hydroxylase (TH) and immediate early gene expression in ventral tegmental area (VTA) or NA regions was examined. A single injection of nicotine increased TH mRNA level at VTA region. GTS, which did not affect the basal TH mRNA expression, attenuated nicotine-induced TH mRNA expression. Nicotine slightly increased both c-fos and c-jun mRNA level and GTS, which did not affect the basal c-fos and c-jun mRNA expression, further enhanced nicotine-induced c-fos and c-jun mRNA level at both VTA and NA regions. Our results suggest that GTS may have an inhibitory action against nicotine-induced DA release in NA region and TH mRNA expression in VTA region. GTS may exert an potentiative effect on both c-fos and c-jun mRNA expression at NA region through inhibiting the release of DA in NA.

Methotrexate suppresses the interleukin-6 induced generation of reactive oxygen species in the synoviocytes of rheumatoid arthritis

Various cytokines and reactive oxygen species (ROS) play a fundamental role in the inflammatory and immunologic processes of rheumatoid arthritis (RA). Methotrexate (MTX) is one of the disease-modifying anti-rheumatic drugs and its effect may be partly due to the modulation of immunologic or inflammatory reactions by some cytokines. In the present study, we investigated the effects of MTX on the gene expression and synthesis of interleukin-6 (IL-6), and the proliferative activity and the production of ROS in the fibroblast-like synoviocytes (FLSs) obtained from the patient of RA. The expression or production of IL-6 was induced spontaneously, and augmented by the addition of recombinant human IL-6 or recombinant human IL-1 beta and TNF-alpha in FLSs. These spontaneous and augmented IL-6 expressions or productions were suppressed by treatment with low-concentration of MTX (1 microg/ml). Also, IL-6 stimulated the proliferation of FLSs, and this IL-6 driven proliferation was inhibited with the treatment of MTX or N-acetylcysteine (NAC, 1 mM). Furthermore, ROS production in FLSs was increased significantly by IL-6, and its effect was also abrogated in the presence of MTX or NAC. These results suggest that inflammatory reaction in the synovium of RA patients could be augmented by the autocrine or other cytokine-induced production of IL-6 with subsequent generation of ROS in the synoviocytes, and the modulations of IL-6 synthesis and ROS production may contribute to the therapeutic effects of MTX for RA.

Current surgical results of retrosigmoid approach in extralarge vestibular schwannomas

BACKGROUND

Vestibular schwannomas (VS) are common tumors that can be cured; they are reported to comprise 6 approximately 8% of all intracranial tumors. The primary objective in the surgery of extralarge VS is total removal of the tumor mass while preserving the facial nerve. In extralarge tumors, complete excision of the tumor carries a significant risk of injuring the facial nerve and adjacent vital brain structures. The authors are reporting the techniques and results of operation on extralarge VS.

METHODS

The material consisted of 30 patients during the last 6 years with surgically treated VS that had a maximal extrameatal diameter exceeding 4 cm. Suboccipital craniotomy and tumor removal was performed with patients in the lateral position. Results and complications of the surgical technique will be reviewed.

RESULTS

Average age of patients was 45.2 years; there was a slight female predominance (1.5:1). Size of the mass ranged from 41 to 70 mm; all were removed by the retrosigmoid transmeatal approach. Peritumoral edema on MRI was seen in 50% (15/30). Total removal was achieved in 73.3% (22/30) with no significant relationship to peritumoral edema. In the cases of total removal, the facial nerve preservation rate was 86.4% (19/22). There was no mortality. Surgical complications were hemorrhage and CSF leakage in 1 case (3%) and 8 cases (26.7%), respectively, but in most of these cases, conservative treatment was adequate. In patients in whom anatomic preservation of the facial nerve was achieved, facial nerve function improved progressively within a year. In all cases except for one with gait disturbance, a good outcome was achieved.

CONCLUSIONS

Our surgical techniques, including the prediction of facial nerve displacement, not using retractors, and replacement of bone, contributed to good surgical results in a series of extralarge VS.

Expression of neuroD/BETA2 in mitotic and postmitotic neuronal cells during the development of nervous system

NeuroD/BETA2, a basic helix-loop-helix transcription factor, has been shown to play a role in tissue-specific differentiation of pancreatic and enteroendocrine cells. To gain further insight into the function of neuroD/BETA2 in the nervous system development, we examined the expression pattern of neuroD/BETA2 during embryonic and postnatal development by using in situ hybridization. Dynamic changes of neuroD/BETA2 expression in the central nervous system were observed during embryogenesis, especially in telencephalon, hippocampus, cerebellum, spinal cord, and olfactory epithelium. Moderate level of expression was also detected in developing pancreas in early embryogenesis. Although the neuroD/BETA2 expression in cerebellum and hippocampus increased over time, expression in cerebral cortex, spinal cord, as well as in fetal pancreas gradually decreased as embryogenesis proceeded. High level of the neuroD/BETA2 expression in developing cerebellum and hippocampus persisted throughout postnatal development and remained at a stable level in the adult brain. Interestingly, neuroD/BETA2 expression was detected not only in postmitotic but also in mitotic cells, as was evident in its expression in external granular layer of cerebellum and granule cells of the dentate gyrus during postnatal development. This observation suggests that neuroD/BETA2 may have a unique role in proliferation, differentiation, or both, of granule cells of cerebellum and dentate gyrus.

Stimulation of astrocyte-enriched culture with arachidonic acid increases proenkephalin mRNA: involvement of proto-oncoprotein and mitogen activated protein kinases

In astrocyte-enriched cultures, arachidonic acid (AA, 100 microM) significantly increased the proenkephalin (proENK) mRNA level (4. 9-fold at 8 h). In addition, AA also increased several AP-1 proteins, such as c-Fos, Fra-1, Fra-2, JunB, JunD, and c-Jun, or AP-1 and ENKCRE-2 DNA-binding activity. As well as AP-1 proteins and their DNA-binding activities, proENK mRNA level induced by AA was reduced by the pretreatment with 15 microM of cycloheximide (CHX; 1.6-fold). AA-dependent increase of proENK mRNA is not mediated by cyclooxygenase- or lipoxygenase-dependent metabolites, or free radicals, because the AA-induced increase of proENK mRNA levels was not affected by indomethacin (10 microM), nordihydroguaiaretic acid (10 microM), or N-acetylcysteine. However, as well as proto-oncoprotein levels, such as Fra-1, Fra-2, c-Jun, JunB, but not JunD, AA-induced increase of proENK mRNA was significantly reduced by the pretreatment with 10 microM of PD98059 (1.3-fold) or 10 microM of SB203580 (1.8-fold). These results strongly suggest that AA rather than one of its metabolites is involved in the increase of proENK mRNA. In addition, the activation of both the p38 and ERK pathways appears to be involved in the AA-induced increase of proENK mRNA via activating the expression of proto-oncoprotein, such as Fra-1, Fra-2, c-Jun, and JunB.

Radiologic and histopathologic changes after Gamma Knife radiosurgery for acoustic schwannoma

Gamma knife radiosurgery (GKRS) is a widely used treatment option for acoustic schwannomas, 3 cm in diameter or less. Between May 1990 and February 1998, 102 acoustic tumors in 101 patients were treated with GKRS. There are 77 patients with a follow-up period of more than six months (mean 55, range 7 to 90 months). Seventy (91%) of these tumors have remained unchanged or reduced in volume. After GKRS there was an increase in volume in seven cases. In four the volume increase affected solid tumour. Among these, three patients were in stable condition and are being observed. One of these patients developed brain stem compression symptoms and was operated. In another three cases, cysts with multiple septa developed medial to the tumor and compressed the brain stem and fourth ventricle, thus necessitating post-GKRS surgery. In these three patients, MRI had shown loss of central contrast enhancement followed by its return. Histological findings at surgery before and after GKRS were compared for these four tumours. In spite of the MRI changes, there were no definite histological findings after GKRS which could be attributed to radiation induced changes. The development of cysts occurred after the treatment of larger tumors.

Two comparisons of the performance of positional scanning and deletion synthesis for the identification of active constituents in mixture combinatorial libraries

Two libraries of 120 compounds each were prepared as individual compounds and as full mixtures. The corresponding scanning and deletion synthesis deconvolution libraries were prepared and tested (L-1210, IC(50)) alongside the individual compounds and mixture libraries. This testing, where the properties of each compound in the mixtures were known, was used to compare the performance of scanning and deletion deconvolution libraries. Each has its own intrinsic strengths, with the former being capable of identifying multiple hits at the expense of accurately identifying the most potent library member, while the latter typically is more sensitive to identifying the most potent hit but at the expense of differentiating weaker activities. The protocols complement one another and together more thoroughly identify potent library members.

A gene expression database for the molecular pharmacology of cancer

We used cDNA microarrays to assess gene expression profiles in 60 human cancer cell lines used in a drug discovery screen by the National Cancer Institute. Using these data, we linked bioinformatics and chemoinformatics by correlating gene expression and drug activity patterns in the NCI60 lines. Clustering the cell lines on the basis of gene expression yielded relationships very different from those obtained by clustering the cell lines on the basis of their response to drugs. Gene-drug relationships for the clinical agents 5-fluorouracil and L-asparaginase exemplify how variations in the transcript levels of particular genes relate to mechanisms of drug sensitivity and resistance. This is the first study to integrate large databases on gene expression and molecular pharmacology.

Spectroscopic properties of fluoroquinolone antibiotics and nanosecond solvation dynamics in aerosol-OT reverse micelles

Among fluoroquinolone antibiotics, ofloxacin (OFL) and norfloxacin (NOR) have piperazinyl groups but flumequine (FLU) does not have this substitutent. The emission spectra of OFL and NOR are strong, broad structureless bands with large Stokes' shifts in water but the emission intensities are very weak in organic solvents. Thus we find that these compounds exist as different chemical species in various solvents. A continuous red shift in the emission bands for OFL and NOR is observed as the water concentration within the aerosol-OT (AOT; sodium 1,4-bis[2-ethylhexyl]sulfosuccinate) micelle increases or temperature of this solution rises. From the fluorescence anisotropy measurements of OFL and NOR, we assume the intramolecular charge transfer after excitation from the nitrogen of the piperazinyl group to the keto oxygen. Theoretical calculations further support this observation. Multifrequency phase and modulation experiments and time-resolved emission spectra clearly show the occurrence of intramolecular charge transfer and the subsequent nanosecond water reorganization around OFL or NOR in the AOT micelle. Upon increasing the water concentration within the AOT micelle, the relaxation rate increases because of the large amount of free water. The emission spectra of FLU do not exhibit any significant response to the physical properties of their environment.

Quickly predicting chemotherapy response to paclitaxel-based therapy in non-small cell lung cancer by early technetium-99m methoxyisobutylisonitrile chest single-photon-emission computed tomography

The purpose of this study was to retrospectively predict the chemotherapy response to paclitaxel in non-small cell lung cancer (NSCLC) using technetium-99m methoxyisobutylisonitrile (Tc-99m MIBI) chest single-photon-emission computed tomography (SPECT) to detect the expression of multidrug-resistance-mediated Mr 170,000 P-glycoprotein. Before chemotherapy with Paclitaxel (Taxol), 30 patients with stage IIIb or IV NSCLC were enrolled in this study. Early chest SPECT 10 min after i.v. injection of Tc-99m MIBI was performed to qualitatively interpret Tc-99m MIBI chest SPECT visually and quantitatively calculate early tumor:normal lung ratios (T:NL) for quick assessment of multidrug-resistant P-glycoprotein expression in NSCLC. On the basis of qualitatively visual interpretation of early Tc-99m MIBI chest SPECT, all of 15 (100%) cases with good response to chemotherapy with Taxol could be detected but 10 (67%) of 15 cases with poor response could not be detected. Early Tc-99m MIBI chest SPECT could correctly predict chemotherapy response in 25 (83%) of 30 of cases. The early T:NL were 3.30 +/- 0.82 for 15 patients with good response and 2.02 +/- 0.19 for 5 patients with poor response. The differences were significant (P < 0.05) by independent Student t tests. However, no significant differences were found for other prognostic factors (age, sex, tumor size, tumor location, stage, and cell type) between good-response and poor-response patients. Early Tc-99m MIBI chest SPECT has the potential to predict chemotherapy response to Paclitaxel.

Mining and visualizing large anticancer drug discovery databases

In order to find more effective anticancer drugs, the U.S. National Cancer Institute (NCI) screens a large number of compounds in vitro against 60 human cancer cell lines from different organs of origin. About 70,000 compounds have been tested in the program since 1990, and each tested compound can be characterized by a vector (i.e., "fingerprint") of 60 anticancer activity, or -[log(GI50)], values. GI50 is the concentration required to inhibit cell growth by 50% compared with untreated controls. Although cell growth inhibitory activity for a single cell line is not very informative, activity patterns across the 60 cell lines can provide incisive information on the mechanisms of action of screened compounds and also on molecular targets and modulators of activity within the cancer cells. Various statistical and artificial intelligence methods, including principal component analysis, hierarchical cluster analysis, stepwise linear regression, multidimensional scaling, neural network modeling, and genetic function approximation, among others, can be used to analyze this large activity database. Mining the database can provide useful information: (a) for the development of anticancer drugs; (b) for a better understanding of the molecular pharmacology of cancer; and (c) for improvement of the drug discovery process.

Bronchial anthracofibrosis (inflammatory bronchial stenosis with anthracotic pigmentation): CT findings

OBJECTIVE

The aim of this study was to describe CT findings of patients with bronchial anthracofibrosis.

CONCLUSION

Atelectasis caused by smooth bronchial narrowing, surrounded by calcified or noncalcified lymph nodes, in elderly and nonsmoking women is a typical finding of anthracofibrosis. Calcified lymph nodes adjacent to the involved bronchi and multifocal involvement of bronchial narrowing may be helpful in differentiating this condition from lung cancer.

Thermostable lipase of Bacillus Stearothermophilus: high-level production, purification, and calcium-dependent thermostability

An efficient expression system was developed for the production of the thermostable lipase from Bacillus stearothermophilus L1 in an Escherichia coli system. A structural gene corresponding to mature lipase was subcloned in the pET-22b(+) expression vector and its expression was induced by IPTG at 30 degrees C in E. coli cells. The lipase activity in a cell-free extract was as high as 448,000 units/g protein, which corresponds to as much as 26% of the total cellular protein and is 77 times higher than that of E. coli RR1/pLIP1. Based on its pI (7.4) and pH stability data reported previously, the L1 lipase was efficiently purified to homogeneity with CM (at pH 6.0) and DEAE (at pH 8.8) column chromatographies with a recovery yield of 62%. The specific activity of the purified enzyme was 1700 units/mg protein when olive oil emulsion was used as a substrate. Its optimum temperature for the hydrolysis of olive oil was 68 degrees C and it was stable up to 55 degrees C for 30 min-incubation. The thermostability increased by about 8-10 degrees in the presence of calcium ions. This calcium-dependent thermostability was confirmed by the tryptophan fluorescence emission kinetics showing that the enzyme starts to unfold at 66 degrees C in the presence of calcium ions but at 58 degrees C in the absence of calcium ions, implying that the calcium ions bind to the thermostable enzyme and stabilize the protein tertiary structure even at such high temperatures.

Detection and characterization of endothelin in transformed human osteoblast cell culture medium

Endothelin-1 (ET-1), a 21 amino acid peptide originally purified from conditioned medium of cultures of porcine aortic endothelial cells, is recognized also as a product of many other cells such as epithelial cells, glial cells, and neurons. It is now recognized that at least ET-1 plays an important role in bone metabolism. It has been shown that ET-1 inhibits osteoclast bone resorption by a direct effect on cell motility and it can also activate phospholipase C in the osteoblast. Furthermore, several studies have shown that ET-1 stimulates the formation of inositol phosphates, the synthesis of DNA, the mobilization of calcium from extra- and intracellular pools, the activation of phospholipase D, and the stimulation of tyrosine phosphorylation in osteoblast-like (MC3T3-E1 and UMR-106) cells. The aim of the present study was to detect and characterize the presence of endothelin in transformed human osteoblast cell culture medium (HTb96) by radioimmunoassay and chromatography methods. Immunoreactive endothelin (IR-ET) was undetectable in the medium incubated at 0.5 and 1 h and was 3.2 +/- 0.2 fmol/10(5) cells (mean +/- SEM, n = 6) at 2 h, 9.5 +/- 0.5 fmol/10(5) cells at 6 h, 19.8 +/- 2.1 fmol/10(5) cells at 24 h, and 23.7 +/- 2.0 fmol/10(5) cells at 48 h, respectively. Sephadex G-25 superfine chromatography and fast protein liquid chromatography studies showed that >90% of IR-ET in the culture medium coeluted with synthetic ET-1. These results show that ET-1 could be formed by transformed human osteoblasts. Further studies should be conducted to elucidate the physiological role of endothelins as possible autocrine, paracrine, or endocrine factors in calcium and bone metabolism.

Biological modification of the fatty acid group in an emulsan by supplementing fatty acids under conditions inhibiting fatty acid biosynthesis

When the concentration of the antibiotic cerulenin was increased up to 3.0 mg/l in medium containing ethanol as a carbon source, the specific growth rate of Acinetobacter calcoaceticus and the fatty acid content of the emulsan decreased from 0.179 h(-1) and 13.9% to 0.015 h(-1) and 3.4%, respectively. The emulsifying activity in medium containing cerulenin decreased with increasing cerulenin concentration. In the culture containing 3.0 mg/l cerulenin, fatty acid biosynthesis was inhibited. Various fatty acids were added to this inhibitory culture as a second carbon source to modify the fatty acid group in the emulsan. When an odd-numbered fatty acid was added, the resulting emulsan was found to have other odd-numbered fatty acids that were not present originally. Among the emulsan produced from even-numbered fatty acids, the emulsan produced from myristic acid (C14) contained the greatest amount of the same-numbered fatty acids. When the amount of supplemental myristic acid was increased, the myristic acid content in the emulsan increased, but its emulsifying activity decreased.

IFN-gamma-dependent delay of in vivo tumor progression by Fas overexpression on murine renal cancer cells

The role of Fas in the regulation of solid tumor growth was investigated. Murine renal carcinoma (Renca) cells were constitutively resistant to Fas-mediated killing in vitro, but exhibited increased expression of Fas and sensitivity to Fas-mediated killing after exposure to IFN-gamma and TNF. Transfected Renca cells overexpressing Fas were efficiently killed in vitro upon exposure to anti-Fas Ab (Jo2). When Fas-overexpressing Renca cells were injected into syngenic BALB/c mice, there was a consistent and significant delay in tumor progression, reduced metastasis, and prolonged survival that was not observed for Renca cells that overexpressed a truncated nonfunctional Fas receptor. The delay of in vivo tumor growth induced by Fas overexpression was not observed in IFN-gamma-/- mice, indicating that IFN-gamma is required for the delay of in vivo tumor growth. However, there was a significant increase of infiltrated T cells and in vivo apoptosis in Fas-overexpressing Renca tumors, and Fas-overexpressing Renca cells were also efficiently killed in vitro by T cells. In addition, a strong therapeutic effect was observed on Fas-overexpressing tumor cells by in vivo administration of anti-Fas Ab, confirming that overexpressed Fas provides a functional target in vivo for Fas-specific ligands. Therefore, our findings demonstrate that Fas overexpression on solid tumor cells can delay tumor growth and provides a rationale for therapeutic manipulation of Fas expression as a means of inducing tumor regression in vivo.

The single minichromosome maintenance protein of Methanobacterium thermoautotrophicum DeltaH contains DNA helicase activity

Previous studies have identified an ATP-dependent DNA helicase activity intrinsic to the human minichromosome maintenance (MCM) complex, composed of MCM subunits 4, 6, and 7 [Ishimi, Y. (1997) J. Biol. Chem. 272, 24508-24513]. In contrast to the presence of multiple MCM genes (at least six) in eukaryotes, the archaeon Methanobacterium thermoautotrophicum DeltaH (mth) genome contains a single open reading frame coding for an MCM protein. In this study we report the isolation of the mthMCM protein overexpressed in Escherichia coli. The purified recombinant protein was found to exist in both multimeric ( approximately 10(3) kDa) and monomeric (76 kDa) forms. Both forms of the protein bind to single-stranded DNA, hydrolyze ATP in the presence of DNA, and possess 3'-to-5' ATP-dependent DNA helicase activities. Thus, a single mthMCM protein contains biochemical properties identical to those associated with the eukaryotic MCM4, -6, and -7 complex. These results suggest that the characterization of the mthMCM protein and its multiple forms may contribute to our understanding of the role of MCM helicase activity in eukaryotic chromosomal DNA replication.

MedMiner: an Internet text-mining tool for biomedical information, with application to gene expression profiling

The trend toward high-throughput techniques in molecular biology and the explosion of online scientific data threaten to overwhelm the ability of researchers to take full advantage of available information. This problem is particularly severe in the rapidly expanding area of gene expression experiments, for example, those carried out with cDNA microarrays or oligonucleotide chips. We present an Internet-based hypertext program, MedMiner, which filters and organizes large amounts of textual and structured information returned from public search engines like GeneCards and PubMed. We demonstrate the value of the approach for the analysis of gene expression data, but MedMiner can also be extended to other areas involving molecular genetic or pharmacological information. More generally still, MedMiner can be used to organize the information returned from any arbitrary PubMed search.

Pulmonary tuberculosis in patients with systematic lupus erythematosus

OBJECTIVE

The purpose of our study was to describe radiologic manifestations of pulmonary tuberculosis in patients with systemic lupus erythematosus.

CONCLUSION

The prevalence of pulmonary tuberculosis was high in patients with systemic lupus erythematosus. Imaging of these patients showed miliary dissemination and patchy consolidation. However, cavitation was rare. These findings may reflect impaired immune response against tuberculous bacilli.

Activation of adenylate cyclase results in down-regulation of c-jun mRNA expression in rat C6 glioma cells

To investigate the possible mechanisms involved in forskolin-induced c-jun mRNA decrease in rat C6 glioma cells, we examined effects of a PKA inhibitor (H-89), a L-type Ca2+ channel blocker (nimodipine), a calmodulin activation inhibitor (calmidazolium chloride) and a Ca2+/calmodulin-dependent protein kinase II inhibitor (KN-62) on forskolin-induced c-jun mRNA down-regulation. H-89 caused a reversal of forskolin-induced c-jun mRNA decrease. Furthermore, nimodipine, KN-62 and calmidazolium chloride partially blocked forskolin-induced c-jun mRNA down-regulation. Our results suggest that activation of adenylate cyclase appears to be involved in a down-regulation of c-jun mRNA expression through a PKA pathway. In addition, L-type calcium channels, calmodulin and Ca2+/calmodulin-dependent protein kinase II may be partially involved in c-jun mRNA down-regulation induced by forskolin.

Biological effects of 1alpha-hydroxy- and 1beta-(hydroxymethyl)-vitamin D compounds relevant for potential colorectal cancer therapy

1alpha,25-dihydroxyvitamin D(3) and two synthetic analogs, 1alpha, 25-dihydroxy-16-ene-23-yne-vitamin D(3) (Ro 23-7553) and 1alpha, 25-dihydroxy-16-ene-24-oxo-vitamin D(3) (JK-1624-3), were tested for their ability to specifically inhibit growth and promote differentiation of human colon cancer cells in comparison with a series of 1beta-(hydroxymethyl) congeners of the natural hormone, such as 1beta-(hydroxymethyl)-3alpha,25(OH)(2)-16-ene,24-oxo-vitamin D(3) (JK-1624-2), 1beta-(hydroxymethyl)-3alpha, 25-dihydroxy-16-ene-26,27-dihomo vitamin D(3) (JK-1626-2), and 1beta-(hydroxymethyl)-3alpha,25-dihydroxy-22,24-diene-26,27- dihomo vitamin D(3) (MCW-EE). Western blot analysis revealed that reduction of cyclin D1 levels is a key mechanism by which the vitamin D compounds under investigation inhibit Caco-2 tumor cell growth. Both the 1alpha-hydroxy- as well as the 1beta-hydroxymethyl-type vitamin D compounds, which exhibit only low affinity for the vitamin D receptor, significantly reduced [(3)H]thymidine DNA labeling in confluent Caco-2 cell cultures. This suggests that high-affinity binding to the vitamin D receptor is not an absolute prerequisite for genomic action on tumor cell growth. Hybrid analogs JK-1624-2 and MCW-EE, although antimitotically active, were rather ineffective in promoting phenotypic differentiation of human colon cancer cells. However, because both compounds also do not promote osteoclast differentiation from hematopoetic bone marrow cells, they still could be used as antimitotic agents in cancer therapy, even at dose levels that, with other analogs, could cause hypercalcemia.

Downregulation of voltage-gated K(+) channels in rat heart with right ventricular hypertrophy

The effects of myocardial hypertrophy on mRNA expression levels of voltage-gated K(+) channels were investigated using monocrotaline (MCT)-induced pulmonary hypertensive rats. The ratio of right ventricle weight to left ventricle plus septum weight on day 28 was increased significantly compared with control rats [control vs. MCT: 0.27 +/- 0.01 vs. 0.58 +/- 0.03 ms (n = 8-13); P < 0.05]. Electrocardiograms showed that QRS duration [control vs. MCT: 26.4 +/- 2.6 ms vs. 31.5 +/- 5.8 ms (n = 6); P < 0.05], Q-T interval [control vs. MCT: 100.8 +/- 8.9 ms vs. 110.0 +/- 4.2 ms (n = 6); P < 0.05] and corrected Q-T interval [Q-T(c); control vs. MCT: 8.4 +/- 0. 7 ms vs. 10.2 +/- 0.4 ms (n = 6); P < 0.05] were prolonged significantly on day 28. mRNA levels of Kv1.2, 1.5, 2.1, 4.2, and 4. 3 for day 28 assessed by ribonuclease protection assays were decreased significantly from control by 60 +/- 10, 76 +/- 3, 58 +/- 5, 81 +/- 5, and 45 +/- 12%, respectively (n = 3; P < 0.005), and Kv1.4 mRNA level for day 28 was unaffected [Kv1.4, control vs. MCT: 1.0 +/- 0.28 vs. 0.88 +/- 0.44 (arbitrary units) (n = 3); not significant (NS)]. On the other hand, there was no significant difference between control and MCT rats in mRNA levels of these Kv channels for day 14 [Kv1.2 (control vs. MCT): 1.0 +/- 0.25 vs. 0.87 +/- 0.18 (n = 3), NS; Kv1.4: 1.0 +/- 0.22 vs. 1.27 +/- 0.37 (n = 3), NS; Kv1.5: 1.0 +/- 0.16 vs. 0.91 +/- 0.28 (n = 3), NS; Kv2.1: 1.0 +/- 0.26 vs. 0.99 +/- 0.25 (n = 3), NS; Kv4.2: 1.0 +/- 0.15 vs. 1.22 +/- 0.28 (n = 3), NS; Kv4.3: 1.0 +/- 0.20 vs. 1.21 +/- 0.28 (n = 3), NS]. These findings suggest that altered ventricular repolarization at the advanced stage of hypertrophy may be the result of an inhibition of gene expression of multiple types of voltage-gated K(+) channels.

Identification and reconstitution of the origin recognition complex from Schizosaccharomyces pombe

The origin recognition complex (ORC), first identified in Saccharomyces cerevisiae (sc), is a six-subunit protein complex that binds to DNA origins. Here, we report the identification and cloning of cDNAs encoding the six subunits of the ORC of Schizosaccharomyces pombe (sp). Sequence analyses revealed that spOrc1, 2, and 5 subunits are highly conserved compared with their counterparts from S. cerevisiae, Xenopus, Drosophila, and human. In contrast, both spOrc3 and spOrc6 subunits are poorly conserved. As reported by Chuang and Kelly [(1999) Proc. Natl. Acad. Sci. USA 96, 2656-2661], the C-terminal region of spOrc4 is also conserved whereas the N terminus uniquely contains repeats of a sequence that binds strongly to AT-rich DNA regions. Consistent with this, extraction of S. pombe chromatin with 1 M NaCl, or after DNase I treatment, yielded the six-subunit ORC, whereas extraction with 0.3 M resulted in five-subunit ORC lacking spOrc4p. The spORC can be reconstituted in vitro with all six recombinant subunits expressed in the rabbit reticulocyte system. The association of spOrc4p with the other subunits required the removal of DNA from reaction mixture by DNase I. This suggests that a strong interaction between spOrc4p and DNA can prevent the isolation of the six-subunit ORC. The unique DNA-binding properties of the spORC may contribute to our understanding of the sequence-specific recognition required for the initiation of DNA replication in S. pombe.