The detection of Epstein-Barr virus in the lesions of salivary glands

Epstein-Barr virus (EBV) is known in association with lymphoid and epithelial lesion. Because the salivary gland is an organ close to the oropharynx, it has a higher incidence of EBV infection and is a possible route of EBV infection. Formalin-fixed, paraffin embedded tissue sections of 87 cases of salivary gland diseases were used for the study of EBV with PCR, in situ PCR for EBNA-1 (EBV nuclear antigen-1), and immunohistochemistry for LMP-1 (latent membrane protein-1). EBV was detected in 12 cases (13.8%): 7 of nonspecific chronic sialadenitis (21.2%), 4 of Warthin's tumors (30.8%), and one lymphoepithelial carcinoma. EBNA-1 was negative in all the other lesions. EBV DNA was detected in the nucleus of epithelial cells and the surrounding lymphocytes. LMP-1 positivity was found in the cytoplasm of epithelial cells. The results of the present study showed that EBV is implicated in some of the inflammatory and neoplastic lesions of the salivary gland in which the lymphocytes are abundant. However, the pathogenesis and mechanism of immortalization and tumorigenesis of the epithelial cells in the salivary glands remain to be determined.

Isozyme-specific inhibitors of protein kinase C translocation: effects on contractility of single permeabilized vascular muscle cells of the ferret

1. The effects on contractility of three peptides reported to inhibit protein kinase C (PKC) translocation in an isozyme-specific manner were studied: a peptide from the C2 domain of conventional PKCs (C2-2), a peptide from the N-terminal variable domain of epsilonPKC (epsilonV1-2) and a peptide (ABP) from the actin-binding domain of epsilonPKC (epsilon(223-228)). 2. Isometric force was directly recorded from individual hyperpermeable ferret portal vein or aortic smooth muscle cells. 3. Phenylephrine contracted permeabilized portal vein cells at pCa 6.7 but not at pCa 7.0. However, phenylephrine did contract aortic cells at pCa 7.0. 4. C2-2 inhibited phenylephrine-induced contraction, but did not affect resting tension, in portal vein cells at pCa 6.7. In aortic cells at either pCa 6.7 or 7.0, C2-2 had no effect on either basal tension or phenylephrine-induced contraction. 5. ABP did not evoke any changes in phenylephrine-induced contraction or baseline tension in either portal vein or aortic cells. 6. epsilonV1-2 inhibited phenylephrine-induced contraction and decreased resting tension in aortic cells at pCa 7.0, but not in portal vein cells at pCa 6.7. 7. Western blots indicated that portal vein cells contained substantially more alphaPKC than aortic cells. Portal vein cells also contained small amounts of betaPKC, which was undetectable in aortic cells. In contrast, aortic cells contained more epsilonPKC than portal vein cells. Even though epsilonPKC was expressed in portal vein and alphaPKC in aorta, imaging studies indicated that they were not translocated in these cell types. 8. These results suggest that the Ca2+-dependent isozymes of PKC (alpha and/or beta) play a major role in contraction of the portal vein but not of the aorta. In contrast, the results are consistent with epsilonPKC, but not Ca2+-dependent PKC isozymes, regulating contractility of the aorta.

Two-dimensional photonic band-Gap defect mode laser

A laser cavity formed from a single defect in a two-dimensional photonic crystal is demonstrated. The optical microcavity consists of a half wavelength-thick waveguide for vertical confinement and a two-dimensional photonic crystal mirror for lateral localization. A defect in the photonic crystal is introduced to trap photons inside a volume of 2.5 cubic half-wavelengths, approximately 0.03 cubic micrometers. The laser is fabricated in the indium gallium arsenic phosphide material system, and optical gain is provided by strained quantum wells designed for a peak emission wavelength of 1.55 micrometers at room temperature. Pulsed lasing action has been observed at a wavelength of 1.5 micrometers from optically pumped devices with a substrate temperature of 143 kelvin.

Blockade of HERG channels expressed in Xenopus oocytes by external H+

We have investigated the effect of external H+ concentration ([H+]o) on the human-ether-a-go-go-related gene (HERG) current (IHERG), the molecular equivalent of the cardiac delayed rectifier potassium current (IKr), expressed in Xenopus oocytes, using the two-microelectrode voltage-clamp technique. When [H+]o was increased, the amplitude of the IHERG elicited by depolarization decreased, and the rate of current decay on repolarization was accelerated. The activation curve shifted to a more positive potential at lower external pH (pHo) values (the potential required for half-maximum activation, V1/2, was: -41.8 mV, -38.0 mV, -33.7 mV, -26.7 mV in pHo 8.0, 7.0, 6.6, 6.2, respectively). The maximum conductance (gmax) was also affected by [H+]o: a reduction of 7.9%, 14.6%, and 22.8% was effected by decreasing pHo from 8.0 to 7.0, 6.6, and 6.2, respectively. We then tested whether this pH effect was affected by the external Ca2+ concentration, which is also known to block HERG channels. When the extracellular Ca2+ concentration was increased from 0.5 mM to 5 mM, the shift in V1/2 caused by increasing [H+]o was attenuated, suggesting that these two ions compete for the same binding site. On the other hand, the decrease in gmax caused by increasing [H+]o was not significantly affected by changing external Ca2+ levels. The results indicate that HERG channels are inhibited by [H+]o by two different mechanisms: voltage-dependent blockade (shift of V1/2) and the decrease in gmax. With respect to the voltage-dependent blockade, the interaction between H+ and Ca2+ is competitive, whereas for the decreasing gmax, their interaction is non-competitive.

Expression and characterization of anti-NCA-95 scFv (CEA 79 scFv) in a prokaryotic expression vector modified to contain a Sfi I and Not I site

The CEA 79 antibody has been used in bone marrow scintigraphy for the differential diagnosis of skeletal tumors and the evaluation of the bone marrow status of patients with various hematological disorders. The specific localization of radio-labeled CEA 79 antibody in bone marrow depends on its reactivity with NCA-95 (nonspecific cross-reacting antigen-95) present on the surface and in the cytosol of human granulocytes and myelopoietic cells. To make a CEA 79 scFv molecule that would be less immunogenic and more penetrating than the intact mouse immunoglobulin, we constructed a pRSET Sfi I/Not I expression vector. The scFv gene was then excised from a pCANTAB 5 E phage display vector by digestion with Sfi I and Not I and inserted into the pRSET Sfi I/Not I expression vector. Upon transformation of a BL21(DE3)pLysS strain of E. coli, CEA 79 scFv became expressed in inclusion bodies requiring a renaturation process for solubilization. The final yield of CEA 79 scFv was 5 mg per a liter of culture. The refolded CEA 79 scFv exhibited an affinity (Kd = 2.1 x 10(-9) M) equivalent to that of the original CEA 79 antibody (K(d) = 3.3 x 10(-9) M) and the same immunoreactivity to CEA and NCA-95 in Western blots and in immunohistochemical staining experiments.

Auxiliary partial orthotopic living donor liver transplantation as an aid for small-for-size grafts in larger recipients

BACKGROUND

In countries where living donors are the only source of liver grafts, restrictions on graft size are a serious obstacle for the expansion of indications for adult recipients. To overcome this problem, auxiliary partial orthotopic liver transplants (APOLT*) was performed on the basis of the concept that the residual native liver would support the graft function until the graft had grown enough to function by itself.

METHODS

APOLT as an aid for small-for-size (SFS) grafts was reviewed retrospectively to evaluate its feasibility. Between April 1995 and March 1998, 20 recipients underwent APOLT, which was indicated because of a SFS graft in 15 of them. The indication was based on the estimated graft/recipient's body weight ratio (GRWR). If the ratio was <0.8%, APOLT was performed. The other 5 patients had a graft with a GRWR >0.8% and underwent APOLT on the basis of the residual native liver supporting the graft function temporarily, 4 for supplementation of the defective enzyme in metabolic liver diseases and one for leaving the potential of the regeneration of the native liver in fulminant hepatic failure. The recipients who underwent APOLT because of a SFS graft were categorized as the SFS group, and the others were the second group.

RESULTS

In the SFS group, the age of the recipients ranged from 13 to 48 (median 23). The original indications of this group were fulminant hepatic failure in 2 recipients, acute deterioration of chronic liver diseases in 3, Wilson's disease in 2, biliary atresia in 4, primary biliary cirrhosis in 3, and primary sclerosing cholangitis (PSC) in one. The actual GRWR ranged from 0.45 to 0.72 (median 0.55). The graft was implanted after resection of the left lateral segment of the native liver. Except in the first two patients, the portal vein to the residual native liver was completely transected so that all of the portal blood drained into the graft liver. This procedure was successful in 9 patients. The cause of death in the other 6 was mainly infection. The mortality rate among the recipients with signs of advanced liver failure, such as massive ascites or hepatic coma, was higher, even though APOLT was used to support the SFS graft. In the second group, in the other five recipients who underwent APOLT for other indications, one recipient with fulminant hepatic failure died of sepsis caused by the dehiscence of bilio-enteric anastomosis.

CONCLUSIONS

APOLT as an aid for a SFS graft is technically viable. This procedure can thus expand the indication of living donor liver transplants for adult recipients when the native liver retains some functional capability to support the grafted liver during the immediate postoperative period.

Structural basis for recognition of the tra mRNA precursor by the Sex-lethal protein

The Sex-lethal (Sxl) protein of Drosophila melanogaster regulates alternative splicing of the transformer (tra) messenger RNA precursor by binding to the tra polypyrimidine tract during the sex-determination process. The crystal structure has now been determined at 2.6 A resolution of the complex formed between two tandemly arranged RNA-binding domains of the Sxl protein and a 12-nucleotide, single-stranded RNA derived from the tra polypyrimidine tract. The two RNA-binding domains have their beta-sheet platforms facing each other to form a V-shaped cleft. The RNA is characteristically extended and bound in this cleft, where the UGUUUUUUU sequence is specifically recognized by the protein. This structure offers the first insight, to our knowledge, into how a protein binds specifically to a cognate RNA without any intramolecular base-pairing.

Angiopoietin-1 is an apoptosis survival factor for endothelial cells

We examined the effect of angiopoietin-1 (Ang1) on apoptosis in human umbilical vein endothelial cells (HUVECs). Ang1 (5-1000 ng/ml) dose-dependently inhibited apoptosis under a serum-deprived state. A significant apoptotic inhibition occurred with as low as 50 ng/ml. Two hundred ng/ml of Ang1 inhibited to approximately 50% of the control apoptotic rates for 96 h. Furthermore, an augmented antiapoptotic effect of Ang1 by the addition of 20 ng/ml vascular endothelial growth factor was observed. This Ang1-induced strong antiapoptotic effect in endothelial cells is a novel and intriguing finding and could be an additional description of Ang1-induced direct biological function.

Blockade of HERG channels expressed in Xenopus laevis oocytes by external divalent cations

We have investigated actions of various divalent cations (Ba2+, Sr2+, Mn2+, Co2+, Ni2+, Zn2+) on human ether-a-go-go related gene (HERG) channels expressed in Xenopus laevis oocytes using the voltage clamp technique. All divalent cations inhibited HERG current dose-dependently in a voltage-dependent manner. The concentration for half-maximum inhibition (Ki) decreased at more negative potentials, indicating block is facilitated by hyperpolarization. Ki at 0 mV for Zn2+, Ni2+, Co2+, Ba2+, Mn2+, and Sr2+ was 0.19, 0.36, 0. 50, 0.58, 2.36, and 6.47 mM, respectively. The effects were manifested in four ways: 1) right shift of voltage dependence of activation, 2) decrease of maximum conductance, 3) acceleration of current decay, and 4) slowing of activation. However, each parameter was not affected by each cation to the same extent. The potency for the shift of voltage dependence of activation was in the order Zn2+ > Ni2+ >/= Co2+ > Ba2+ > Mn2+ > Sr2+, whereas the potency for the decrease of maximum conductance was Zn2+ > Ba2+ > Sr2+ > Co2+ > Mn2+. The kinetics of activation and deactivation were also affected, but the two parameters are not affected to the same extent. Slowing of activation by Ba2+ was most distinct, causing a marked initial delay of current onset. From these results we concluded that HERG channels are nonselectively blocked by most divalent cations from the external side, and several different mechanism are involved in their actions. There exist at least two distinct binding sites for their action: one for the voltage-dependent effect and the other for reducing maximum conductance.

Chemical shift perturbation studies of the interactions of the second RNA-binding domain of the Drosophila sex-lethal protein with the transformer pre-mRNA polyuridine tract and 3' splice-site sequences

The interactions of the second RNA-binding domain of the Drosophila melanogaster Sex-lethal protein (Sxl RBD2) with the oligoribonucleotides, GUUUUUUUU (GU8) and CUAGUG, representing the sequences surrounding an alternative 3'-splicing site of the transformer pre-mRNA (GU8CUAGUG), were studied using heteronuclear two-dimensional NMR techniques. The 1H and 15N chemical shifts of the backbone amide resonances upon titration of Sxl RBD2 with each of these RNAs were recorded. It was found that Sxl RBD2 can bind not only to the polyuridine tract, GU8, but also to the downstream 3' splice-site sequence, CUAGUG, with similar affinities. In contrast, a nonspecific sequence, C8, did not bind to Sxl RBD2. This result is consistent with previous in vitro RNA-selection and UV-cross-linking results which indicated that the Sex-lethal protein binds to the uridine stretch and the AG dinucleotide in the consensus sequence, AUnNnAGU. In both cases, the chemical-shift perturbations were significant for almost the same amino acid residues, including the two central beta-strands formed by the RNP2-motif and RNP1-motif with the two highly conserved aromatic residues (Y214 and F256) in the middle. As the first RNA-binding domain of Sex-lethal (Sxl RBD1) has a characteristic aliphatic residue at one of the two corresponding positions (I128 and F170), Y214 of Sxl RBD2 was replaced by Ile using site-directed mutagenesis. On the one hand, the 1H and 15N chemical-shift perturbations indicated that GU8 binds to the same interface of mutant Sxl RBD2 as of wild-type Sxl RBD2, although its binding affinity was decreased significantly. On the other hand, the specific binding of Sxl RBD2 to CUAGUG was abolished almost completely by the Y-->I mutation. Taken together, the present results indicate that the interface residues that bind with GU8 and CUAGUG are much the same, but the role of the Y214 residue is clearly different between these two target sequences.

Small cell osteogenic sarcoma of the ribs: cytological, immunohistochemical, and ultrastructural study with literature review

Small cell osteosarcoma (OS) is a rare variant of OS that is composed of small cells resembling those of Ewing's sarcoma (ES) with recognizable osteoid. This type of tumor often creates difficulty in making a diagnosis when tissue samples do not include osteoid. The frequent sites are long bones and until now there have been no reported cases arising in the ribs. A case is reported here of small cell OS occurring in the ribs of a 37-year-old female with its aspiration cytologic and electron microscopic characteristics. In the cytologic smear, the small round neoplastic cells were individually scattered or arranged in small nests. The nuclei were hyperchromatic and oval with no visible nucleoli. Ultrastructurally, the nuclei had a round or oval euchromatic chromatin pattern and occasional nucleoli. The scanty cytoplasm contained a small quantity of organelles including either tubular or dilated cisternae of RER, a few mitochondria, and free or polyribosomes. Other organelles were absent. Although the electron microscope sample of this case did not include bone mineral (hydroxy apatite), the electron microscopic features of the tumor cells were unique and useful for exclusion of other small round cell neoplasms.

Molecular cloning and characterization of a novel angiopoietin family protein, angiopoietin-3

Using homology-based PCR, we have isolated cDNA encoding a novel member (491 amino acids) of the angiopoietin (Ang) family from human adult heart cDNA and have designated it angiopoietin-3 (Ang3). The NH2-terminal and COOH-terminal portions of Ang-3 contain the characteristic coiled-coil domain and fibrinogen-like domain that are conserved in other known Angs. Ang3 has a highly hydrophobic region at the N-terminus (approximately 21 amino acids) that is typical of a signal sequence for protein secretion. Ang3 mRNA is most abundant in adrenal gland, placenta, thyroid gland, heart and small intestine in human adult tissues. Additionally, Ang3 is a secretory protein, but is not a mitogen in endothelial cells.

Epstein-Barr virus and CD21 expression in gastrointestinal tumors

Epstein-Barr virus (EBV) was found in 7-17% of gastric adenocarcinomas, including lymphoepithelioma-like carcinomas, although its significance has not been clear. In addition, 20-30% of malignant lymphomas arising in the gastrointestinal tract have been known to express the EBV genome. Several lines of evidence indicate that EBV has been shown to infect both B lymphocytes and squamous epithelial cells via CD21 molecule in vivo and in vitro. The expression of CD21 in EBV-associated gastrointestinal tumors, however, has remained controversial. To determine the presence of CD21, an EBV receptor, in the EBV-associated gastrointestinal tumors, we, first, examined the EBV genome in sixty seven patients with either gastrointestinal adenocarcinomas or malignant lymphomas using in situ hybridization (ISH) for EBV-encoded small RNAs (EBERs) and PCR for EBNA-1. Then, the investigation of CD21 expression was performed only in the EBV-positive tumors with immunohistochemical method for CD21 antigen on paraffin sections. EBERs were detected in 6 out of 26 gastric adenocarcinomas, 2 of 24 colonic adenocarcinomas, and 8 of 17 malignant lymphomas. EBERs were more prevalent in the malignant lymphomas originating from the small and large intestine (6/6) than from the stomach (2/11), and were detected in both B and T cell phenotypes. EBNA-1 was amplified in 11 of 16 EBERs-positive cases. Interestingly, however, none of the EBV-positive six gastric adenocarcinomas and eight malignant lymphomas expressed the CD21 on the cell surfaces or cytoplasm of both tumor cells and adjacent normal epithelial cells. These results suggest that EBV infection in the gastrointestinal malignancies would be mediated via different routes besides the CD21 or a new receptor distinct from CD21.

A role for MAP kinase in differentiated smooth muscle contraction evoked by alpha-adrenoceptor stimulation

The purpose of this study was to investigate the potential role of mitogen-activated protein (MAP) kinase in smooth muscle contraction by monitoring MAP kinase activation, caldesmon phosphorylation, and contractile force during agonist stimulation. Isometric tension in response to KCl and phenylephrine (PE) was measured from strips of ferret aorta. MAP kinase activation was monitored by Western blot using a phosphospecific p44/p42 MAP kinase antibody. Caldesmon phosphorylation was assessed using specific phosphocaldesmon antibodies. We report here that treatment of smooth muscle strips with PD-098059, a specific inhibitor of MAP kinase kinase, did not detectably modify the KCl-evoked contraction but significantly inhibited the contraction to PE in the absence of extracellular Ca2+. In this experimental condition, where the contraction occurs in the absence of increases in 20-kDa myosin light chain phosphorylation, PD-098059 also inhibited significantly MAP kinase and caldesmon phosphorylation. Collectively, these results demonstrate a direct cause-and-effect relationship between MAP kinase activation and Ca2+-independent smooth muscle contraction and support the concept of caldesmon phosphorylation as the missing link between both events.

Chondromyxoid fibroma of the distal phalanx of the great toe: a tumor with unusual histological findings

Chondromyxoid fibroma (CMF) rarely arises in the distal phalanx of the foot and less than 20 cases have been reported in the literature. It has also been known to show a wide spectrum of histology mimicking other primary bone tumors. An unusual case of CMF arising in the distal phalanx of the left great toe is reported because of its unique anatomic site of origin and histology. A 53-year-old female presented with a slow growing, painful great toe of the left foot which she had had for 3 years. She had first noticed the mass 25 years ago. On admission, plain X-ray revealed an osteolytic mass with a sclerotic margin expanding to the distal phalanx of the great toe. Interestingly, the lesion was microscopically composed of hypercellular chondromyxoid lobules separated by hypocellular fibrous tissue, which is in contrast to the typical histology of CMF. In addition, the lesion showed an aggregate of tumor cells with pleomorphic multinucleate or giant nuclei within the chondromyxoid matrix, which were not similar to the osteoclast-like type. Perhaps these unusual histological findings may be associated with its long duration and presenting location.

Permanent exposure of mucin-secreting HT-29 cells to benzyl-N-acetyl-alpha-D-galactosaminide induces abnormal O-glycosylation of mucins and inhibits constitutive and stimulated MUC5AC secretion

Previous work has shown that treatment of HT-29 methotrexate (MTX) cells with benzyl-N-acetyl-alpha-D-galactosaminide results in profound changes in mucin oligosaccharide chains. To analyse in depth the effect of this drug, we first determined the structure of mucin oligosaccharide chains synthesized by HT-29 MTX cells and the changes induced by permanent drug exposure. Mucins from untreated cells contained nine monosialylated structures (core types 1, 2, 3 and 4) and four disialylated structures (types 1, 2 and 4). Core 1 structures predominated, in particular NeuAcalpha2-3Galbeta1-3GalNAc-ol. Exposure of HT-29 MTX cells to benzyl-N-acetyl-alpha-D-galactosaminide from days 2-21 resulted in a decrease in intracellular mucins and both their sialic acid and galactose content, and an increased T (Galbeta1-3GalNAcalpha-O-Ser/Thr) and Tn (GalNAcalpha-O-Ser/Thr) antigenicity. A 3-fold increase in both Galbeta1-3GalNAc alpha2, 3-sialyltransferase activity and mRNA expression was detected. At the ultrastructural level, T-antigen was not detectable in mucin droplets in control cells, but was strongly expressed in intracytoplasmic vesicles in treated cells. In these cells, MUC1 and MUC3 transcripts were up-regulated, whereas MUC2, MUC5B and MUC5AC were down-regulated. Furthermore, constitutive and secretagogue-induced MUC5AC secretion was reduced and no mucus layer was detected. In conclusion, benzyl-N-acetyl-alpha-D-galactosaminide induces abnormal O-glycosylation and altered regulation of MUC5AC secretion.

GalNAc-alpha-O-benzyl inhibits NeuAcalpha2-3 glycosylation and blocks the intracellular transport of apical glycoproteins and mucus in differentiated HT-29 cells

Exposure for 24 h of mucus-secreting HT-29 cells to the sugar analogue GalNAc-alpha-O-benzyl results in inhibition of Galbeta1-3GalNAc:alpha2,3-sialyltransferase, reduced mucin sialylation, and inhibition of their secretion (Huet, G., I. Kim, C. de Bolos, J.M. Loguidice, O. Moreau, B. Hémon, C. Richet, P. Delannoy, F.X. Real., and P. Degand. 1995. J. Cell Sci. 108:1275-1285). To determine the effects of prolonged inhibition of sialylation, differentiated HT-29 populations were grown under permanent exposure to GalNAc-alpha-O-benzyl. This results in not only inhibition of mucus secretion, but also in a dramatic swelling of the cells and the accumulation in intracytoplasmic vesicles of brush border-associated glycoproteins like dipeptidylpeptidase-IV, the mucin-like glycoprotein MUC1, and carcinoembryonic antigen which are no longer expressed at the apical membrane. The block occurs beyond the cis-Golgi as substantiated by endoglycosidase treatment and biosynthesis analysis. In contrast, the polarized expression of the basolateral glycoprotein GP 120 is not modified. Underlying these effects we found that (a) like in mucins, NeuAcalpha2-3Gal-R is expressed in the terminal position of the oligosaccharide species associated with the apical, but not the basolateral glycoproteins of the cells, and (b) treatment with GalNAc-alpha-O-benzyl results in an impairment of their sialylation. These effects are reversible upon removal of the drug. It is suggested that alpha2-3 sialylation is involved in apical targeting of brush border membrane glycoproteins and mucus secretion in HT-29 cells.

Habitat islands, genetic diversity, and gene flow in a Patagonian rodent

The effects of terrestrial habitat islands on gene flow and genetic diversity in animal populations have been predicted and discussed in theoretical terms, but empirical data are needed to test these predictions and provide an understanding of the relationships of life-history characteristics to genetics of insular species. We studied saxicolous mice (Phyllotis xanthopygus) in Patagonia to explore genetic structure, phylogeography, and gene flow in a species inhabiting natural habitat islands. Phylogeographic analyses based on mtDNA sequences revealed two haplotype clades, which presumably reflect early Pleistocene factors that temporarily separated the mice into two geographically isolated groups. The Río Chubut, which lies within a glacial drainage basin bisecting northern Patagonia, might have affected gene flow in the species. Although we anticipated isolation by distance and founder phenomena associated with habitat islands, in some habitat patches we found evidence of high local genetic diversity. The amount of divergence in the mitochondrial cytochrome b gene (approximately 3.4%) in animals at a single locality could best be explained through a combination of historical factors and metapopulation source-sink theory. Demographic shifts, dispersal, and episodic recolonization are important in the life history and genetic population structure of P. xanthopygus.

Effect of petroleum ether extract of Panax ginseng roots on proliferation and cell cycle progression of human renal cell carcinoma cells

Panax ginseng roots have long been used as a medicinal herb in oriental countries. We have investigated anti-proliferative effects of lipid soluble Panax ginseng components on human renal cancer cell lines. Petroleum ether extract of Panax ginseng roots (GX-PE) or its partially purified preparation (7:3 GX) was added to cultures of three human renal cell carcinoma (RCC) cell lines, A498, Caki-1, and CURC II. Proliferation of RCC cells was estimated by a [3H]thymidine incorporation assay and cell cycle distribution was analyzed by flow cytometry. GX-PE, 7:3 GX, panaxydol and panaxynol inhibited proliferation of all three RCC cell lines in a dose dependent manner in vitro with an order of potency, 7:3 GX > panaxydol > panaxynol = GX-PE. Additive effect of interleukin 4 was also demonstrated, most prominently in Caki-1 which responded poorly to GX-PE alone. Analysis of cell cycle in CURC II and Caki-1 treated with GX-PE demonstrated increase in G1 phase population and corresponding decrease in S phase population. The present study demonstrated that proliferation of human RCC cell lines were inhibited by lipid soluble components of Panax ginseng roots by blocking cell cycle progression at G1 to S phase transition.

Advanced glycation end products increase retinal vascular endothelial growth factor expression

Advanced glycation end products (AGEs) are linked with the development of diabetic retinopathy; however, the pathogenic mechanisms are poorly defined. Vascular endothelial growth factor (VEGF) levels are increased in ischemic and nonischemic diabetic retina, and VEGF is required for the development of retinal and iris neovascularization. Moreover, VEGF alone can induce much of the concomitant pathology of diabetic retinopathy. In this study, we found that AGEs increased VEGF mRNA levels in the ganglion, inner nuclear, and retinal pigment epithelial (RPE) cell layers of the rat retina. In vitro, AGEs increased VEGF mRNA and secreted protein in human RPE and bovine vascular smooth muscle cells. The AGE-induced increases in VEGF expression were dose- and time-dependent, inhibited by antioxidants, and additive with hypoxia. Use of an anti-VEGF antibody blocked the capillary endothelial cell proliferation induced by the conditioned media of AGE-treated cells. AGEs may participate in the pathogenesis of diabetic retinopathy through their ability to increase retinal VEGF gene expression.

Voltage-dependent blockade of HERG channels expressed in Xenopus oocytes by external Ca2+ and Mg2+

1. We expressed the human eag-related gene (HERG), which is known to encode the delayed rectifier K+ current (IKr) in cardiac muscle, in Xenopus oocytes. Using a two-microelectrode voltage clamp technique, the effect of external Ca2+ and Mg2+ on the HERG current (IHERG) was investigated. 2. When [Ca2+]o was increased, the amplitude of outward IHERG elicited by depolarization decreased, and the rate of current onset slowed. The rate of current decay observed on repolarization was greatly accelerated. The threshold and fully activated potential of IHERG shifted to a more positive potential. On the other hand, the inactivation property represented by the negative slope of the I-V curve and the instantaneous conductance of IHERG were little affected by [Ca2+]o. 3. The effect of [Ca2+]o on IHERG can be interpreted using the channel blockade model. The blockade is voltage dependent; smaller dissociation constants (KM) at more negative potentials indicate that block is facilitated by hyperpolarization. KM changes e-fold for 14.5 mV and the fractional electrical distance of the binding site calculated from this value is 0.86. 4. Blockade by a low concentration of Ca2+ (0.5 mM) was inhibited by increasing [K+]o (from 2 to 20 mM), whereas blockade by a high concentration of Ca2+ (5 mM) was not affected by varying [K+]o, indicating that there is competition between permeating ions and blocking ions. 5. The effect of [Mg2+]o on IHERG was qualitatively similar to that of [Ca2+]o, but the potency was lower. 6. These results suggest that external Ca2+ and Mg2+ block the HERG channel in a voltage- and time-dependent manner, resulting in a voltage dependence which has been regarded as a property of the activation gate.

Persistent and heterogenous expression of the cyclin-dependent kinase inhibitor, p27KIP1, in rat hearts during development

We have previously shown that there were differential and dramatic decreases of cyclin and cyclin-dependent kinase (CDK) activities in cardiomyocytes during the neonatal period. The activity of CDKs control cell cycle progression, and this activity is regulated positively and negatively by association of CDKs with cyclins and cyclin-dependent kinase inhibitors (CKIs), respectively. While the INK family (p15(INK4B)/p16(INK4A)/p18(INK4C)/p19(INK4D)) of CKIs is not detectable in hearts, the KIP/CIP family (p21(CIP1), p27(KIP1) and p57(KIP2)) of CKIs is detectable in most organs including the heart. Differential and dramatic changes of the KIP/CIP family (p21(CIP1), p27(KIP1) and p57(KIP2)) of CKIs were detected in rat hearts during development. The mRNA and protein levels of p21(CIP1) and p57(KIP2) were readily detectable in hearts at gestational and early postnatal periods and decreased thereafter. The mRNA levels of p27(KIP1) in ventricles were high during the gestational period, and did not change until day 30 postnatal, then were decreased slightly in 90-day-old rats. The protein levels of p27(KIP1) increased significantly in the early postnatal period, then were expressed persistently, although levels decreased slightly in the adult period. However, protein levels of p27(KIP1) in atria did not change during development. Variable immuno-staining patterns of p27(KIP1) were observed at different periods of development and in various locations in myocardium. During the gestational period, approximately 35-50% of myocardial cells in the cardiac wall were p27(KIP1) immuno-positive and were distributed diffusely. These p27(KIP1) immunopositive cells increased predominantly in endocardial and mid-portion areas of ventricular myocardium at the early postnatal period. This heterogenous pattern of p27(KIP1) protein expression persisted to adult hearts though the percentage of p27(KIP1) immuno-positive cells decreased slightly. High magnification revealed that more than 50% of adult cardiomyocytes were p27(KIP1) immuno-positive and that p27(KIP1) was located solely in nuclei. These results indicate that p27(KIP1) may be an important inhibitor of CDK activities in cardiomyocytes during early postnatal development and may block the re-entrance of adult cardiomyocytes into the cell cycle after injury.

Identification of alternatively spliced Na(+)-Ca2+ exchanger isoforms expressed in the heart

Alternatively spliced isoforms of Na(+)-Ca2+ exchanger were found from various tissues and species. RT-PCR amplification was performed on the basis of our cloned mouse cardiac Na(+)-Ca2+ exchanger and four alternatively spliced isoforms of Na(+)-Ca2+ exchanger were identified. Three (NCX1.3, NCX1.4, and NCX1.12) of them were first identified in the heart, and one isoform (NCX1.12) was a novel spliced variant. These four spliced variants were present in the embryonic and adult atria and ventricles. Different cell types of the heart expressed different spliced isoforms of Na(+)-Ca2+ exchanger. Southern blot analysis indicated that the Na(+)-Ca2+ exchanger gene existed as a single copy in the mouse genome. Thus, the Na(+)-Ca2+ exchanger isoforms expressed in mouse heart are consistent with being produced by alternative splicing and they may have different functions in various cell types in the mouse heart.