Plasma and urinary vascular endothelial growth factor and diabetic nephropathy in Type 2 diabetes mellitus

AIMS

Vascular endothelial growth factor (VEGF) has been implicated in the pathogenesis of diabetes mellitus. We determined whether alterations of plasma and urinary VEGF levels are related to diabetic nephropathy in Type 2 diabetic patients.

METHODS

One hundred and seven patients and 47 healthy controls were studied. Study subjects were divided into four groups using urinary albumin-to-creatinine ratio (ACR): a non-diabetic healthy control group (n = 47), a normoalbuminuric diabetic group (n = 37), a microalbuminuric diabetic group (n = 37) and an overt proteinuric diabetic group (n = 33). VEGF levels were measured by enzyme-linked immunosorbent assay.

RESULTS

(i) Urinary VEGF concentrations were significantly higher in the diabetic groups, even at the normoalbuminuric stage (log VEGF/Cr, normoalbuminuria; 4.33 +/- 1.06 vs. control; 3.53 +/- 0.79, P = 0.009). Urinary VEGF excretions increased as diabetic nephropathy advanced. (ii) Plasma and urinary VEGF levels were higher in hypertensive diabetic patients than in the normotensive individuals with diabetes. (iii) In those with diabetes, plasma VEGF levels were found to be positively correlated with plasma urea (r = 0.398, P = 0.039) and urinary ACR (r = 0.251, P = 0.044), and urinary VEGF to be positively correlated with urinary ACR (r = 0.645, P < 0.001), and creatinine (r = 0.336, P = 0.009), and to be negatively correlated with serum albumin (r = -0.557, P < 0.001). Urinary VEGF and serum creatinine were independently correlated with urinary ACR.

CONCLUSIONS

Urinary excretion of VEGF increased during the earlier stage of diabetic nephropathy and was significantly correlated with urinary albumin excretion. This suggests that urinary VEGF might be used as a sensitive marker of diabetic nephropathy and for predicting disease progression.

Taurine transport mechanism through the blood-brain barrier in spontaneously hypertensive rats

Taurine levels in the brain decrease when an animal is subjected to pathological conditions, such as ischemia-anoxia and seizure, but they tend to increase in hypertension. The present study investigated the blood-brain barrier (BBB) transport of [3H]-labelled taurine in spontaneously hypertensive rats (SHR) using internal artery carotid perfusion (ICAP) at a rate of 4 ml/min for 10, 15 and 30 seconds. The volume of distribution in brain (VD) and the permeability surface area product (PS) of [3H]-taurine through the BBB in SHR were calculated. The PS value for taurine at 15 s was higher than at the longer perfusion times. This could result from taurine efflux back into blood occurring after 15 s. As in the case of normotensive rats, taurine was shown to enter the brain via the sodium and chloride ion dependent carrier system.

Role of reactive oxygen species in apoptosis induced by N-ethylmaleimide in HepG2 human hepatoblastoma cells

We have previously reported that N-ethylmaleimide induces apoptosis through activation of K(+), Cl(-)-cotransport in HepG2 human hepatoblastoma cells. In this study, we investigated the role for reactive oxygen species as a mediator of the apoptosis induced by N-ethylmaleimide. N-ethylmaleimide induced a significant elevation of intracellular level of reactive oxygen species. Treatment with antioxidants (N-acetyl cysteine, N,N'-diphenyl-p-phenylenediamine) which markedly suppressed generation of reactive oxygen species, significantly inhibited the N-ethylmaleimide-induced activation of K(+), Cl(-)-cotransport and apoptosis. Inhibitors of NADPH oxidase (diphenylene iodonium, apocynin, D-(+)-neopterine) also significantly blunted the generation of reactive oxygen species, activation of K(+), Cl(-)-cotransport and apoptosis induced by N-ethylmaleimide. These results suggest that reactive oxygen species generated through activation of NADPH oxidase may play a role in the N-ethylmaleimide-induced stimulation of K(+), Cl(-)-cotransport and apoptosis in HepG2 cells.

Characterization of dioxin-like activity of sediments from a Czech river basin

Synthetic organic chemicals are present in environmental compartments as complex mixtures and therefore their potential effects are difficult to predict. In this study, in vitro bioassays using wild-type fish and rat hepatoma cell lines and their corresponding recombinant cell systems were used to evaluate 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-like activity in extracts of sediments collected from rivers of the Czech Republic. All the sediment extracts elicited statistically significant responses in all the cell lines tested. For most sediment extracts, a complete dose-response relationship was obtained. The maximal efficacy of the samples was between 57 and 143% of the maximal induction elicited by TCDD. Greater responsiveness, sensitivity, and reproducibility were observed for recombinant than wild-type cells. Cell line-specific differences in the sensitivity to compounds present in the complex sediment extracts were observed. The TCDD equivalents (TCDD-EQs) determined from the different cell bioassays were correlated. Greater concentrations of TCDD-EQs were obtained with fish cell lines. The TCDD-EQs calculated from the results of chemical analysis of toxic equivalents (TEQs) were in good agreement with those determined by bioassays; the arly hydrocaron receptor (AhR)-effects of the identified chemicals appear to be generally additive. This indicates that most of the TCDD-like activity was accounted for by the compounds identified and quantified by instrumental analysis. Fractionation along with mass-balance calculations allowed identification of the active fractions and classes of compounds. Polycyclic aromatic hydrocarbons (PAHs) were found to be responsible for most of the AhR-mediated activity in sediments.

Deflazacort increases osteoclast formation in mouse bone marrow culture and the ratio of RANKL/OPG mRNA expression in marrow stromal cells

Information on precise effects of deflazacort on bone cell function, especially osteoclasts, is quite limited. Therefore, the present study was undertaken to test effects of deflazacort on osteoclast-like cell formation in mouse bone marrow cultures and on the regulation of osteoprotegerin (OPG) and its ligand (RANKL) mRNA expressions by RT-PCR in the ST2 marrow stromal cells. TRAP-positive mononuclear cells increased after the treatment of deflazacort at 10(-9) to 10(-7) M alone for 6 days in a dose-dependent manner. Number of TRAP-positive multi-nucleated cells (MNCs) increased significantly with combined treatment of deflazacort at 10(-7) M and 1,25-(OH)2D3 at 10(-9) M compared to that of cultures treated with 1,25-(OH)2D3 alone (p<0.05). Exposure to deflazacort at 10(-7) M in the presence of 1,25-(OH)2D3 at 10(-9) M in the last 3-day culture had greater stimulatory effect on osteoclast-like cell formation than that of the first 3-day culture did. Deflazacort at 10(-10) -10(-6) M downregulated OPG and upregulated RANKL in mRNA levels in a dose-dependent manner. These observations suggest that deflazacort stimulate osteoclast precursor in the absence of 1,25-(OH)2D3 and enhance differentiation of osteoclasts in the presence of 1,25-(OH)2D3. These effects are, in part, thought to be mediated by the regulation of the expression of OPG and RANKL mRNA in marrow stromal cells.

Effect of phthalates on the stability and performance of AgBF4-PVP membranes for olefin/paraffin separation

The presence of a phthalate in dry polymer membranes consisting of polyvinylpyrrolidone (PVP) and AgBF4, AgBF4-PVP, provides long-term stability and better performance for the separation of propylene/propane gas mixtures.

Apoptosis signal-regulating kinase 1 controls the proapoptotic function of death-associated protein (Daxx) in the cytoplasm

Although Daxx (death-associated protein) was first reported to mediate the apoptotic signal from Fas to JNK in the cytoplasm, other data suggested that Daxx is mainly located in the nucleus as a transcriptional regulator. Here, we demonstrated that cellular localization of Daxx could be determined by the relative concentration of a proapoptotic kinase, apoptosis signal-regulating kinase 1 (ASK1) by using immunofluorescence and transcriptional reporter assay. ASK1 sequestered Daxx in the cytoplasm and inhibited the repressive activity of Daxx in transcription. In addition, Daxx was bound to the activated Fas only in the presence of ASK1, accelerating the Fas-mediated apoptosis. These results suggest that Daxx requires ASK1 for its cytoplasmic localization and Fas-mediated signaling. Taken together, we could conclude that ASK1 controls the dual function of Daxx as a transcriptional repressor in the nucleus and as a proapoptotic signal mediator in the cytoplasm.

Identification of a mutation in the human raloxifene response element of the transforming growth factor-beta 3 gene

The human transforming growth factor-beta 3 (TGF-beta 3) is an important cytokine to maintain bone mass by inhibiting osteoclast differentiation. Recently raloxifene response element (RRE), a new enhancer with a polypurine sequence for estrogen receptor (ER)-mediated gene activation, was identified on the TGF-beta 3 gene. Functional analysis of the RRE-mediated pathway has shown that this would be an important pathway for bone preserving effect. We found a novel mutation in the RRE sequence by single-strand conformational polymorphism analysis in one of 200 Korean women. Cloning and sequencing revealed a heterozygote in which one allele had an insertion of 20 nucleotides (AGAGAGGGAGAGGGAGA GGG) between nucleotide +71 and +72 and a point mutation at nucleotide +75 (G-A transition), and the other allele had normal sequence. The insertion was a nearly perfect tandem duplication of the wild type DNA sequence. The bone mineral density of the affected woman was not much lower than that of age-matched controls. Transient transfection of the mutant allele showed no significantly different activity compared with that of the wild type allele. These observations suggest that the heterozygote variation of the RRE sequence seems not to be operative in determination of bone mass.

Polychlorinated naphthalenes, biphenyls, dibenzo-p-dioxins, and dibenzofurans as well as polycyclic aromatic hydrocarbons and alkylphenols in sediment from the Detroit and Rouge Rivers, Michigan, USA

Sediment from the upper Detroit and lower Rouge Rivers in southeastern Michigan, USA, were analyzed to examine the distribution of polychlorinated naphthalenes (PCNs), biphenyls (PCBs), dibenzo-p-dioxins (PCDDs), and dibenzofurans (PCDFs) as well as polycyclic aromatic hydrocarbons (PAHs) and alkylphenolic compounds such as butylphenol, octylphenol, and nonylphenol (NP). Sediments from a non-point source location in Lake Michigan were also analyzed for target compounds. Concentrations of target compounds in the upper Detroit and lower Rouge Rivers varied considerably among locations, and notable spatial variation existed. Concentrations of PCNs and PCDDs/PCDFs in sediments from the upper Detroit and lower Rouge Rivers ranged from 0.08 to 187 ng/g and 69 to 1420 pg/g dry weight, respectively. Total PCBs, PAHs, and NP concentrations ranged from 8 to 25,000, 17 to 44,000, and < 10 to 60,000 ng/g dry weight, respectively. Concentrations of all target compounds except PCNs were significantly correlated with total organic carbon content of sediments. Similarly, concentrations of PCBs, PCDDs, and PCDFs were significantly correlated with each other. The distribution of organic contaminants in the upper reaches of the Detroit River and lower Rouge River suggested the presence of localized, but multiple, sources of contamination for each compound class. Conners Creek combined sewer overflow has been identified as one of the potential sources for the upper Detroit River, where the highest concentrations PCBs and PCDDs/PCDFs were found. Polycyclic aromatic hydrocarbon and NP concentrations were consistently high in sediment from the lower Rouge River. Analysis of data from selected locations suggested that PCNs contributed a greater proportion of the dioxin-like activity than PCBs and PCDDs/PCDFs contributed.

Stability of the disulfide bond in an avidin-biotin linked chimeric peptide during in vivo transcytosis through brain endothelial cells

Drug delivery of potential neuropharmaceuticals with poor intrinsic permeability through the blood-brain barrier (BBB), such as peptides, is facilitated by coupling to a vector that undergoes receptor-mediated transcytosis through the endothelial cells of brain microvessels. When cleavable disulfide linkers are used in the synthesis of such "chimeric peptides", it is crucial that the S-S-bridge is stable during transcytosis. Cleavage within endothelial cells could result in sequestration of the drug moiety instead of passage through the BBB. In the present study the metabolically stable opioid peptide [3 H]DALDA ([3 H]Tyr-DArg-Phe-Lys-NH2 ) was used as a model drug. It was monobiotinylated with the cleavable biotin reagent sulfosuccinimidyl 2-(biotinamido)ethyl-1,3'-dithiopropionate (NHS-SS-biotin) to obtain bio-[3 H]DALDA. The biotinylated peptide was then bound to a vector for brain delivery after intravenous injection in rats, a covalent conjugate of streptavidin and the transferrin receptor monoclonal antibody, OX26. Compared to peptide without vector, brain uptake of bio-[3 H]DALDA after was increased 18-fold to reach 0.12% of the injected dose per g tissue. Transcranial microdialysis was performed for 60 min after an intravenous bolus of chimeric peptide, followed by reverse phase HPLC of dialysate. Stability of the chimeric peptide during transport through the BBB into brain extracellular fluid was concluded from the absence of a peptide peak generated by disulfide cleavage.

Role of pertussis toxin-sensitive G-proteins in intracellular Ca2+ release and apoptosis induced by inhibiting cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channels in HepG2 human hepatoblastoma cells

Previously, we have reported that inhibition of cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channels by glibenclamide induced intracellular Ca2+ release from IP(3)-sensitive stores and apoptosis in HepG2 human hepatoblastoma cells (Kim JA, Kang YS, Lee SH, Lee EH, Yoo BH, Lee YS. 1999. Biochem Biophys Res Commun 261:682-688). In this study we investigated the upstream signals involved in the mechanism of these actions of glibenclamide. Treatment with glibenclamide initiated production of inositol 1,4,5-trisphosphate (IP(3)) in a dose- and time-dependent manner. The glibenclamide-induced formation of IP(3) was significantly inhibited by CFTR activators (levamisole and bromotetramisole). The intracellular Ca2+ release and apoptosis induced by glibenclamide were significantly suppressed by treatment with phospholipase C (PLC) inhibitors (U-73122 and manoalide) or by pretreatment with pertussis toxin (PTx). In addition, PTx-catalyzed ADP-ribosylation of GTP-binding proteins (G-proteins) was markedly enhanced by treatment with glibenclamide in a time-dependent manner. Taken together, these results suggest that PTx-sensitive G-proteins coupled to PLCbeta may mediate the intracellular Ca2+ release and apoptosis induced by inhibiting CFTR Cl- channels in HepG2 cells. These results further suggest that the PTx-sensitive G-proteins may be a valuable target for the therapeutic intervention of human hepatomas.

Involvement of K(+)-Cl(-)-cotransport in the apoptosis induced by N-ethylmaleimide in HepG2 human hepatoblastoma cells

The role of K(+)-Cl(-)-cotransport in apoptosis in human cancer cells was investigated. N-Ethylmaleimide, a K(+)-Cl(-)-cotransport activator, induced apoptosis in a dose-dependent manner in HepG2 human hepatoblastoma cells. N-Ethylmaleimide induced Cl(-)-dependent K(+) efflux, indicating that K(+)-Cl(-)-cotransport is functionally present in HepG2 cells. Calyculin-A and genistein, inhibitors of K(+)-Cl(-)-cotransport, significantly prevented both K(+)-Cl(-)-cotransport activation and apoptosis induced by N-ethylmaleimide. These results demonstrate, for the first time, a novel role for K(+)-Cl(-)-cotransport in apoptosis in human hepatoma cells. These results further suggest that K(+)-Cl(-)-cotransport may be a valuable target for therapeutic interventions for human hepatoma.

Facilitated olefin transport by reversible olefin coordination to silver ions in a dry cellulose acetate membrane

The highly selective dry complex membrane AgBF4-cellulose acetate (CA) was prepared and tested for the separation of ethylene/ethane and propylene/propane mixtures. The maximum selectivity for olefin over paraffin was found to be 280 for the ethylene/ethane mixture and 200 for the propylene/propane mixture. Solid-state interactions of AgBF4 with cellulose acetate (CA) and/or olefins have been investigated by using FT-IR, UV, and X-ray photoelectron spectroscopy (XPS). FT-IR and XPS studies clearly show that the silver ions are coordinated by carbonyl oxygen atoms among three different types of oxygen atoms present in CA-two in the acetate group and one in the ether linkage. Upon incorporation of AgBF4 into CA, the carbonyl stretching frequency of the free cellulose acetate at 1750 cm(-1) shifts to a lower frequency by about 41 cm(-1). The binding energy corresponding to a carbonyl oxygen atom in the O 1s XPS spectrum shifts to a more positive binding energy by the incorporation of AgBF4. Reversible olefin coordination to silver ions has been observed by FT-IR and UV studies. Treatment of the AgBF4-CA membrane placed in a gas cell with propylene produces a propylene-coordinated membrane in which coordinated propylene is easily replaced by other olefins such as 1,3-butadiene.

Role of NAD(P)H oxidase in the tamoxifen-induced generation of reactive oxygen species and apoptosis in HepG2 human hepatoblastoma cells

Previously, tamoxifen (TAM) has been shown to induce apoptosis through elevation of intracellular Ca2+ in HepG2 human hepatoblastoma cells. In this study we investigated the role of reactive oxygen species (ROS) in the TAM-induced apoptosis, and interrelationship between intracellular Ca2+ and ROS. TAM induced a slow and sustained increase in intracellular ROS level. An antioxidant, N-acetylcysteine significantly inhibited both ROS production and apoptosis induced by TAM, suggesting that ROS may play an essential role in the TAM-induced apoptosis. In a time frame ROS generation followed intracellular Ca2+ increase, and the extracellular and intracellular Ca2+ chelation with EGTA and BAPTA/AM, respectively, completely inhibited the TAM-induced ROS production, indicating that intracellular Ca2+ may mediate the ROS generation. Inhibitors of NAD(P)H oxidase, diphenylene iodonium, phenylarsine oxide and neopterine, significantly blocked the TAM-induced ROS generation and apoptosis, implying that this oxidase may act as a source enzyme for the production of ROS. These results suggest that non-phagocytic NAD(P)H oxidase may play a novel role as a mediator of the apoptosis associated with intracellular Ca2+ in HepG2 cells.

Transanally injected triamcinolone acetonide in levator syndrome

PURPOSE

Several treatments are used for the treatment of levator syndrome, such as rectal massage, biofeedback, and galvanic stimulation. But their effects are inconsistent, and multiple treatment sessions are usually required. Triamcinolone acetonide and lidocaine mixture was injected locally into the tenderest point in levator syndrome under the hypothesis that levator syndrome is caused by tendinitis of pelvic floor musculature.

METHODS

A mixture of 40 mg of triamcinolone acetonide and 1 ml of 2 percent lidocaine was injected into the tenderest point transanally in 104 patients (33 males; mean age, 51 years) with levator syndrome from December 1996 to May 1998 at Daehang Clinic. Additional injections were repeated at two-week intervals to a maximum of three injections in cases of poor response. Follow-up was performed prospectively concerning patient's perception of pain level using a visual analog scale. Depending on the response, the patients were classified into four groups: pain-free, good, fair, and no response. More than 50 percent pain reduction was classified as "good," and less than 49 percent reduction as "fair."

RESULTS

The injection regions, where the tenderest points were identified on digital rectal compression, were left anterior anal canal in 71.2 percent of patients, right anterior in 3.8 percent of patients, and posterior in 25 percent of patients. The results of treatment were as follows: at three months after injection, response was classified as pain-free in 36.8 percent of patients, good in 35 percent of patients, fair in 19.5 percent of patients, and no response in 8.7 percent of patients; at six months the response was pain-free in 30.1 percent of patients, good in 46.5 percent of patients, fair in 18.2 percent of patients, and no response in 5.2 percent of patients. Most patients, except 8.7 percent at three months and 5.2 percent at six months, experienced treatment benefits. There were no complications during the follow-up periods.

CONCLUSION

Transanal injection of triamcinolone acetonide and lidocaine mixture into the tenderest point is such a simple, safe, and very effective modality that it can be recommended as a primary therapy for levator syndrome.

Inhibitors of Na+/Ca2+ exchanger prevent oxidant-induced intracellular Ca2+ increase and apoptosis in a human hepatoma cell line

Oxidative stress appears to be implicated in the pathogenesis of various diseases including hepatotoxicity. Although intracellular Ca2+ signals have been suggested to play a role in the oxidative damage of hepatocytes, the sources and effects of oxidant-induced intracellular Ca2+ increases are currently debatable. Thus, in this study we investigated the exact source and mechanism of oxidant-induced liver cell damage using HepG2 human hepatoma cells as a model liver cellular system. Treatment with 200 microM of tert-butyl hydroperoxide (tBOOH) induced a sustained increase in the level of intracellular reactive oxygen intermediates (ROI) and apoptosis, assessed by 2',7'-dichlorofluorescein fluorescence and flow cytometry, respectively. Antioxidants, N-acetyl cysteine (NAC) or N,N'-diphenyl-p-phenylenediamine significantly inhibited both the ROI generation and apoptosis. In addition, tBOOH induced a slow and sustained increase in intracellular Ca2+ concentration, which was completely prevented by the antioxidants. An intracellular Ca2+ chelator, bis-(o-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid/cetoxymethyl ester significantly suppressed the tBOOH-induced apoptosis. These results imply that activation of an intracellular Ca2+ signal triggered by increased ROI may mediate the tBOOH-induced apoptosis. Both intracellular Ca2+ increase and induction of apoptosis were significantly inhibited by an extracellular Ca2+ chelator or Na+/Ca2+ exchanger blockers (bepridil and benzamil), whereas neither Ca2+ channel antagonists (verapamil and nifedipine) nor a nonselective cation channel blocker (flufenamic acid) had an effect. These results suggest that tBOOH may increase intracellular Ca2+ through the activation of reverse mode of Na+/Ca2+ exchanger. However, tBOOH decreased intracellular Na+ concentration, which was completely prevented by NAC. These results indicate that ROI generated by tBOOH may increase intracellular Ca2+ concentration by direct activation of the reverse mode of Na+/Ca2+ exchanger, rather than indirect elevation of intracellular Na+ levels. Taken together, these results suggest that the oxidant, tBOOH induced apoptosis in human HepG2 cells and that intracellular Ca2+ may mediate this action of tBOOH. These results further suggest that Na+/Ca2+ exchanger may be a target for the management of oxidative hepatotoxicity.

Brain uptake and the analgesic effect of oxytocin--its usefulness as an analgesic agent

To establish the usefulness of oxytocin (OT) as an analgesic for women in delivery, the pharmacokinetic parameters and blood-brain barrier (BBB) permeability of [3H]OT were obtained using an intravenous injection technique or the internal carotid artery perfusion/capillary depletion (ICAP/CDM) method. Brain uptake of OT was similar to that of sucrose, plasma space marker, indicating that OT has a poor BBB permeability. Moreover, the analgesic effects of OT injected through the jugular vein on nociception were evaluated by the tail-flick method. The antinociceptive effects of OT injected at a dose of 0.2 mg/kg or 2 mg/kg were dose-dependent. In addition, the analgesic effects of OT on the CNS were unaffected by naloxone, a m-receptor antagonist. In a similar manner to the opioid system, OT may play a modulatory role in antinociception.

Caveolin internalization by heat shock or hyperosmotic shock

We investigated the cellular localization of caveolin, a landmark protein of caveolae, by indirect immunofluorescence after heat shock or hyperosmotic shock. Caveolin was internalized to the perinucleus by heat shock (43 degrees C) and relocalized in the plasma membrane after recovery of NIH3T3 cells at 37 degrees C for 4 h. The caveolin internalization was also observed after cells were exposed to hyperosmotic shock. Caveolin disappeared from detergent-insoluble complexes in the heat-shocked cells, but alkaline phosphatase was still there, suggesting that their responses to heat shock are quite different even though both of them were enriched in detergent-insoluble complexes of normal cells. Caveolin was internalized by the actin depolymerizer cytochalasin D, but not by the tubulin depolymerizer nocodazole. In addition, cellular exposure to hydrogen peroxide caused caveolin internalization along with disintegrated microfilaments and intact microtubules. Since cellular exposure to heat shock showed disintegrated microfilaments but intact microtubules, caveolin internalization might be due to depolymerized microfilaments. When cells were exposed to heat shock and allowed to recover for 4 h, actin depolymerization and caveolin internalization were not induced by a second heat shock, suggesting that some heat shock protein(s) might prevent actin depolymerization and caveolin internalization.

Ca2+ influx mediates apoptosis induced by 4-aminopyridine, a K+ channel blocker, in HepG2 human hepatoblastoma cells

Apoptosis appears to be implicated in the pathogenesis and therapeutic applications of cancer. In this study we investigated the induction of apoptosis by 4-aminopyridine (4-AP), a K(+) channel blocker, and its mechanism in HepG2 human hepatoblastoma cells. 4-AP reduced cell viability and induced DNA fragmentation, a hallmark of apoptosis, in a dose-dependent manner. In addition, 4-AP induced a sustained increase in intracellular Ca(2+) concentration, which was completely inhibited by the extracellular Ca(2+) chelation with EGTA. 4-AP also induced Mn(2+) influx, indicating that the 4-AP-induced increased intracellular Ca(2+) levels were due to activation of Ca(2+) influx pathway. 4-AP also depolarized membrane potential that was measured by using di-O-C(5)(3), a voltage-sensitive fluorescent dye. 4-AP-induced Ca(2+) influx was significantly inhibited not by voltage-operative Ca(2+) channel blockers (nifedipine or verapamil), but by flufenamic acid (FA), a known nonselective cation channel blocker. Quantitative analysis of apoptosis by the flow cytometry revealed that treatment with either FA or BAPTA, an intracellular Ca(2+) chelator, significantly inhibited the 4-AP-induced apoptosis. Taken together, these results suggest that the observed 4-AP-induced apoptosis in the HepG2 cells may result from Ca(2+) influx through the activation of voltage-sensitive Ca(2+)-permeable non-selective cation channels. These results further suggest that membrane potential change by modulation of K(+) channel activity may be involved in the mechanism of apoptosis in human hepatoma cells.

Involvement of Ca2+ influx in the mechanism of tamoxifen-induced apoptosis in HepG2 human hepatoblastoma cells

The signaling mechanism of tamoxifen (TAM)-induced apoptosis was investigated in HepG2 human hepatoblastoma cells which do not express the estrogen receptor (ER). TAM induced cytotoxicity and DNA fragmentation, a hallmark of apoptosis, in a dose-dependent manner. TAM increased the intracellular concentration of Ca2+. This effect was completely inhibited by the extracellular Ca2+ chelation with EGTA. TAM also induced a Mn2+ influx, indicating that TAM activated Ca2+ influx pathways. This action of TAM was significantly inhibited by flufenamic acid (FA), a known non-selective cation channel blocker. Quantitative analysis of apoptosis by flow cytometry revealed that treatment with either FA or BAPTA, an intracellular Ca2+ chelator, significantly inhibited TAM-induced apoptosis. These results suggest that intracellular Ca2+ signals may play a central role in the mechanism of the TAM-induced apoptotic cell death in ER-negative HepG2 cells.

An antibody-avidin fusion protein specific for the transferrin receptor serves as a delivery vehicle for effective brain targeting: initial applications in anti-HIV antisense drug delivery to the brain

In the present study a novel Ab-avidin fusion protein has been constructed to deliver biotinylated compounds across the blood brain barrier. This fusion molecule consists of an Ab specific for the transferrin receptor genetically fused to avidin. The Ab-avidin fusion protein (anti-TfR IgG3-CH3-Av) expressed in murine myeloma cells was correctly assembled and secreted and showed both Ab- and avidin-related activities. In animal models, it showed much longer serum half-life than the chemical conjugate between OX-26 and avidin. Most importantly, this fusion protein demonstrated superior [3H]biotin uptake into brain parenchyma in comparison with the chemical conjugate. We also delivered a biotinylated 18-mer antisense peptide-nucleic acid specific for the rev gene of HIV-1 to the brain. Brain uptake of the HIV antisense drug was increased at least 15-fold when it was bound to the anti-TfR IgG3-CH3-Av, suggesting its potential use in neurologic AIDS. This novel Ab fusion protein should have general utility as a universal vehicle to effectively deliver biotinylated compounds across the blood-brain barrier for diagnosis and/or therapy of a broad range of CNS disorders such as infectious diseases, brain tumors as well as Parkinson's and Huntington's diseases.

Chromosomal localization of ESTs obtained from human fetal liver via BAC-mediated FISH mapping

A total of 55 expressed sequence tags (ESTs) randomly chosen from our collection of fetal liver ESTs were mapped to chromosomes by fluorescence in situ hybridization (FISH) mapping techniques. To generate FISH mapping probes, the genomic DNAs for each EST were selected by screening an arrayed human bacterial artificial chromosome (BAC) library. In total, 73 BACs were used for mapping of the 55 ESTs. Among them, 70 BACs representing 52 ESTs unequivocally mapped to single chromosomal regions. The remaining 3 BACs representing 3 ESTs were localized to multiple regions, suggesting that BACs may have very low chimerism. Our mapping results were compared with EST mapping databases deposited in NCBI. Thirty-six of 55 ESTs corresponded to previously mapped positions of ESTs, 2 ESTs mapped to different positions from previously determined ones, and it was found that 17 ESTs have been mapped on new locations from this study. These mapping data may be used for completing the framework of the human physical map, and also for providing a good starting point for searching disease-related genes.

Glibenclamide induces apoptosis through inhibition of cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channels and intracellular Ca(2+) release in HepG2 human hepatoblastoma cells

Glibenclamide, an inhibitor of cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channels, induced apoptosis in a dose- and time-dependent manner in HepG2 human hepatoblastoma cells. Glibenclamide increased intracellular Ca(2+) concentration, which was significantly inhibited by Ca(2+) release blockers dantrolene and TMB-8. BAPTA/AM, an intracellular Ca(2+) chelator, and the Ca(2+) release blockers significantly inhibited glibenclamide-induced apoptosis. Glibanclamide also increased intracellular Cl(-) concentration, which was significantly blocked by CFTR Cl(-) channel activators levamisole and bromotetramisole. These activators also significantly inhibited both intracellular Ca(2+) release and apoptosis induced by glibenclamide. The expression of CFTR protein in the cells was confirmed by Western blot analysis. These results suggest that glibenclamide induced apoptosis through inhibition of CFTR Cl(-) channels and intracellular Ca(2+) release and that this protein may be a good target for treatment of human hepatomas.

Inhibitory effects of constituents of Gastrodia elata Bl. on glutamate-induced apoptosis in IMR-32 human neuroblastoma cells

The inhibitory effects of the constituents of Gastrodia elata Bl. (GE) on glutamate-induced apoptosis in human neuronal cells were investigated using IMR32 human neuroblastoma cells. Glutamate (GLU) induced DNA fragmentation, a hallmark of apoptosis, in a dose-dependent manner. GLU also induced a slow and sustained increase in intracellular Ca2+ concentration. Treatment with EGTA, an extracellular Ca2+ chelator, in a nominal Ca2+-free buffer solution abolished the GLU-induced intracellular Ca2+ increase, indicating that GLU stimulated Ca2+ influx pathway in the IMR32 cells. BAPTA, an intracellular Ca2+ chelator, significantly inhibited the GLU-induced apoptosis assessed by the flow cytometry measuring hypodiploid DNA content indicative of apoptosis, implying that intracellular Ca2+ rise may mediate the apoptotic action of GLU. Vanillin (VAN) and p-hydroxybenzaldehyde (p-HB), known constituents of GE, significantly inhibited both intracellular Ca2+ rise and apoptosis induced by GLU. These results suggest that the apoptosis-inhibitory actions of the constituents of GE may account, at least in part, for the basis of their antiepileptic activities. These results further suggest that intracellular Ca2+ signaling pathway may be a molecular target of the constituents of GE.