Physiological transport forces govern drug distribution for stent-based delivery

BACKGROUND

The first compounds considered for stent-based delivery, such as heparin, were chosen on the basis of promising tissue culture and animal experiments, and yet they have failed to stop restenosis clinically. More recent compounds, such as paclitaxel, are of a different sort, being hydrophobic in nature, and their effects after local release seem far more profound. This dichotomy raises the question of whether drugs that have an effect when released from a stent do so because of differences in biology or differences in physicochemical properties and targeting.

METHODS AND RESULTS

We applied continuum pharmacokinetics to examine the effects of transport forces and device geometry on the distribution of stent-delivered hydrophilic and hydrophobic drugs. We found that stent-based delivery invariably leads to large concentration gradients, with drug concentrations ranging from nil to several times the mean tissue concentration over a few micrometers. Concentration variations were a function of the Peclet number (Pe), the ratio of convective to diffusive forces. Although hydrophobic drugs exhibited greater variability than hydrophilic drugs, they achieved higher mean concentrations and remained closer to the intima. Inhomogeneous strut placement influenced hydrophilic drugs more negatively than hydrophobic drugs, dramatically affecting local concentrations without changing mean concentrations.

CONCLUSIONS

Because local concentrations and gradients are inextricably linked to biological effect, our results provide a potential explanation for the variable success of stent-based delivery. We conclude that mere proximity of delivery devices to tissues does not ensure adequate targeting, because physiological transport forces cause local concentrations to deviate significantly from mean concentrations.

[A multicenter clinical study on clinical effects of meglumine cyclic adenylate in treating patients with chronic pulmonary heart disease]

OBJECTIVE

To observe the clinical effects of meglumine cyclic adenylate (MCA) in treating patients with chronic pulmonary heart disease.

METHODS

785 patients with chronic pulmonary heart disease were divided into two groups: MCA group and control group. Both groups of patients were treated with the same ordinary methods, but MCA was given in the MCA group. The period of treatment was 5-7 days. The degree of improvement in clinical symptoms, signs, ECG, pulmonary ventilation function and arterial blood gas analysis of the two groups before and after treatment were compared.

RESULTS

The rates of improvement in clinical symptoms and signs were 92.2% and 73.6% in MCA group and control group respectively. VC increased (426 +/- 123) ml and (313 +/- 145) ml respectively as compared with the values before the treatment. FEV(1) increased (134 +/- 54) ml and (95 +/- 55) ml, PEF increased (0.78 +/- 0.32) L/s and (0.47 +/- 0.32) L/s and PaO(2) increased (23.4 +/- 9.5) mm Hg and (17.3 +/- 10.4) mm Hg respectively. The rates of ECG improvement were 63.7% and 41.2% respectively. There was significant difference between the two groups (P < 0.01 and 0.05).

CONCLUSION

Significant therapeutic effects were obtained in treating patients of chronic pulmonary heart disease with respiratory and cardiac failure by using ordinary treatment measures combined with MCA injection.

Acute and long-term outcomes of stenting in coronary vessel > 3.0 mm, 3.0-2.5 mm, and < 2.5 mm

We compared the acute and long-term outcomes of stentings in coronary vessels > 3.0 mm, 3.0-2.5 mm, and < 2.5 mm. A total of 1,152 patients underwent coronary stenting was divided into three groups based on the reference vessel size. Group A consisted of 598 patients (667 lesions) with a reference vessel diameter > 3.0 mm, group B 485 patients (544 lesions) with a reference vessel diameter of 3.0-2.5 mm, and group C 114 patients (119 lesions) with a reference vessel diameter < 2.5 mm. The procedural success, stent thrombosis, and in-hospital cardiac event rate were similar in the three groups. At 6-month angiographic follow-up, the lesion restenotic rate was significantly higher in the small-vessel group (14%, 22%, and 26% in groups A, B, and C, respectively; P = 0.011). These differences appeared to result from a lesser acute gain and a lesser net gain in small-vessel group; the late luminal loss was similar in the three groups. During a follow-up duration of 28 +/- 3 months, group C patients had a significantly lower rate of event-free survival than the group A and B patients (71% vs. 85% and 82%; P = 0.002). Stepwise regression analysis demonstrated that complex lesion (P = 0.032) and long lesion (P = 0.046) are independent predictors of restenosis in very-small-vessel (< 2.5 mm) stenting. In conclusion, the acute results of stenting in small coronary arteries appear safe and feasible with a high procedural success rate and a low incidence of stent thrombosis. Stenting in patients with a small coronary artery appears to have a similar in-hospital cardiac event rate, but a higher angiographic restenosis rate and a lower event-free survival rate, compared to stenting in patients with a larger coronary artery. The predictors of restenosis in very-small-vessel stenting are complex lesions and long lesions. Cathet Cardiovasc Intervent 2001;53:314-322.

In vivo pharmacokinetics of selective mu-opioid peptide agonists

Recent evidence suggests that highly selective mu-opioid agonists may provide good analgesia with less development of tolerance and dependence. H-Tyr-D-Arg-Phe-Lys-NH2 (DALDA) and H-Dmt-D-Arg-Phe-Lys-NH2 ([Dmt1]DALDA) were found to display high binding affinity and much greater selectivity for the mu-opioid receptor (K(i)delta/K(i)mu) > 10,000) compared with H-Tyr-D-Ala-Gly-MePhe-Gly-ol (DAMGO). In addition, [Dmt1]DALDA was 3000-fold more potent than morphine when administered intrathecally. A potential problem with peptide analogs as therapeutic agents is their susceptibility to enzymatic degradation in vivo and short elimination half-lives. In this study, we compared the stability of DAMGO, DALDA, and [Dmt1]DALDA after systemic administration in sheep. Peptide concentrations were measured using high performance liquid chromatography-mass spectrometry. When incubated in sheep blood at 37 degrees C, DAMGO, DALDA, and [Dmt1]DALDA were stable over 2 h. When given intravenously to sheep, the apparent volume of distribution was 50 to 80 ml/kg for all three peptides, suggesting that distribution was limited to blood volume. Plasma clearance of DAMGO (223 ml/kg/h) was 10-fold faster than DALDA and [Dmt1]DALDA (24 ml/kg/h), and their elimination half-lives were 0.24, 1.5, and 1.8 h, respectively. The half-lives of DALDA and [Dmt1]DALDA are even longer than morphine or meperidine in sheep. These favorable pharmacokinetic properties of DALDA and [Dmt1]DALDA, together with their mu-selectivity, potency, and long duration of action, make them ideal candidates as opioid analgesics.

Tetracyclines inhibit activated B cell function

Tetracyclines have recently been shown to exert a number of pleiotropic anti-inflammatory and immunomodulatory activities, independent of their antibiotic properties. These include the ability to inhibit metalloproteinases (MP), a class of enzymes involved in crucial cellular functions such as the shedding of soluble mediators and their receptors from the cell surface, as well as interaction with, and remodeling of, the extracellular matrix. Here we report that doxycycline at therapeutic concentrations (1--5 microg/ml) significantly suppresses Ig secretion and class switching by in vitro activated murine B cells. Suppression of Ig secretion correlates with a decrease in levels of mRNA for the terminal B cell differentiation-associated genes Blimp-1 and mad-4, as well as to a reduction in expression of the plasma cell markers Syndecan-1 and J chain. Inhibition of class switching occurs at the recombination stage and is also induced by other MP inhibitors, including tetracycline analogs lacking antibiotic activity and the chemically unrelated hydroxamate KB8301. These novel, direct effects of MP inhibitors on B lymphocytes suggest an intrinsic role for MP in B cell activation and likely explain some of the observed in vivo immunomodulatory properties of tetracyclines. Moreover, these findings have significant implications for tetracycline therapy in Ig-mediated autoimmune or allergic diseases and raise questions about the use of doxycycline-inducible transgenic systems for the study of B cell function.

Molecular epidemiology of preterm delivery: methodology and challenges

Preterm delivery (PTD) appears to be a complex trait determined by both genetic and environmental factors. Few studies have examined genetic influence on PTD. The overall goal of our study is to examine major candidate genes of PTD and to test gene-environment interactions. Our study includes 500 preterm trios, including 500 preterm babies and their parents and 500 maternal age-matched term controls. We will perform the transmission/disequilibrium test (TDT) on candidate genes thought to be important in each of the four biological pathways of PTD: (1) decidual chorioamionotic inflammation: interleukin 1 (IL-1), IL-6, and tumour necrosis factor (TNF); (2) maternal and fetal stress: corticotropin-releasing hormone (CRH); (3) uteroplacental vascular lesions: methylenetereahydrofolate reductase (MTHFR); and (4) susceptibility to environmental toxins: GSTM1, GSTT1, CYP1A1, CYP2D6, CYP2E1, NAT2, NQO1, ALDH2, and EPHX. We will also perform standard case-control analyses on the 500 preterm cases and 500 term controls to examine gene-environment interactions. The major environmental, nutritional and social factors as well as clinical variables known or suspected to be associated with PTD will be used to test for gene-environment interactions. This study integrates epidemiological and clinical data as well as genetic markers along major pathogenic pathways of PTD. The findings from this study should improve our understanding of genetic influences on PTD and gene-environment interactions.

Association of asthma with beta(2)-adrenergic receptor gene polymorphism and cigarette smoking

Recent studies have suggested that two polymorphisms of the beta(2)-adrenergic receptor (beta(2)AR) gene at codons 16 (arginine to glycine) and 27 (glutamine to glutamate) affect an individual's airway responsiveness, or response to acute or chronic beta(2)-agonist therapy but are not risk factors for asthma. We hypothesize that there is an interaction effect on asthma between the beta(2)AR gene polymorphisms and cigarette smoking. A case-control study was conducted in 128 asthma cases and 136 control individuals identified from 10,014 studied subjects in rural Anqing, China. Allele-specific polymerase chain reaction (PCR) was used to genotype beta(2)AR gene polymorphisms. Multiple logistic regression was used to adjust for potential confounding factors. We found a marginally significant interaction between cigarette smoking and beta(2)AR-16 genotype after adjusting for important confounding factors (p = 0.06). Specifically, we found that compared with never-smoking Gly-16 homozygotes, those ever-smokers who are Arg-16 homozygotes had a significantly increased risk of asthma (odds ratio [OR] = 7.81; 95% confidence interval [CI]: 2.07 to 29.5). This association showed a clear dose-response relationship with the number of cigarettes smoked. However, there was no significant association of asthma with polymorphisms of the beta(2)AR at position 27 (OR = 1.38; 95% CI: 0.69 to 2.73). Our study suggests a gene-environment interaction between the Arg-16 genotype and ever cigarette smoking with respect to the susceptibility of an individual to asthma.

Rabbit EPO gene and cDNA: expression of rabbit EPO after intramuscular injection of pDNA

Erythropoietin (EPO) cDNA was cloned from kidney total RNA of a NZW rabbit. The cDNA comprises a 588-bp open reading frame encoding a 195 amino acid protein with distinguishable regions of high of homology to other mammalian EPOs. Intramuscular injection of mice with a rabbit EPO expression plasmid resulted in a significant hematocrit increase. A rabbit genomic DNA fragment was also cloned using the rabbit EPO cDNA. This 4312-bp genomic DNA fragment contains sequences homologous to the mouse EPO promoter and hypoxia-responsive enhancer. In addition, the genomic DNA also presents a high degree of conservation to other regions involved in hypoxia response. Sequence divergence in the 3' UTR may indicate differences in regulation of mRNA stability or response to low oxygen tension.

Glucagon-like peptide 1 receptor signaling influences topography of islet cells in mice

Glucagon-like peptide 1 (GLP-1) amplifies glucose-induced insulin release in vivo and in vitro. Activation of GLP-1 receptor (GLP-1R) signaling leads to differentiation of exocrine cells towards a beta-cell phenotype in vitro and stimulation of islet cell proliferation in vitro and in vivo, suggesting a potential role for GLP-1 in the modulation of islet growth and differentiation. To determine whether basal levels of GLP-1R signaling are essential for islet development, we examined islet cell composition and topography in GLP-1R-/- mice. Total beta-cell volume and number are not altered, but the topography of beta cells is markedly different in GLP-1R-/- mice compared with GLP-1R+/+ controls. The distribution of beta cells is shifted from large to small and medium-sized islets in the absence of GLP-1R signaling (large islets: 50 +/- 3% in GLP-1R+/+ vs 28 +/- 4% in GLP- 1R-/-, P < 0.01 and medium islets: 32 +/- 2% in GLP- 1R+/+ vs 48 +/- 3% in GLP-1R-/-, P < 0.001). Furthermore, GLP-1R-/- islets exhibit abnormalities in cell topography, with two to threefold more centrally located alpha cells detected in GLP-1R-/- islets. These alterations in alpha- and beta-cell topography indicate that basal levels of GLP-1 signaling in the normal rodent are involved in the normal cellular organization of the endocrine pancreas.

Gα16Couples Chemoattractant Receptors to NF-κB Activation

The guanine nucleotide-binding regulatory protein alpha-subunit, Galpha(16), is primarily expressed in hemopoietic cells, and interacts with a large number of seven-membrane span receptors including chemoattractant receptors. We investigated the biological functions resulting from Galpha(16) coupling of chemoattractant receptors in a transfected cell model system. HeLa cells expressing a kappaB-driven luciferase reporter, Galpha(16), and the formyl peptide receptor responded to fMLP with a approximately 7- to 10-fold increase in luciferase activity. This response was accompanied by phosphorylation of IkappaBalpha and elevation of nuclear kappaB-DNA binding activity, indicating activation of NF-kappaB. In contrast to Galpha(16), expression of Galpha(q), Galpha(13), and Galpha(i2) resulted in a marginal increase in kappaB luciferase activity. A GTPase-deficient, constitutively active Galpha(16) mutant (Q212L) could replace agonist stimulation for activation of NF-kappaB. Furthermore, expression of Galpha(16) (Q212L) markedly enhanced TNF-alpha-induced kappaB reporter activity. The Galpha(16)-mediated NF-kappaB activation was paralleled by an increase in phospholipase C-beta activity, and was blocked by pharmacological inhibitors of protein kinase C (PKC) and by buffering of intracellular Ca(2+). The involvement of a conventional PKC isoform was confirmed by the finding that expression of PKCalpha enhanced the effect of Galpha(16), and a dominant negative PKCalpha partially blocked Galpha(16)-mediated NF-kappaB activation. In addition to formyl peptide receptor, Galpha(16) also enhanced NF-kappaB activation by the C5a and C3a receptors, and by CXC chemokine receptor 2 and CCR8. These results suggest a potential role of Galpha(16) in transcriptional regulation downstream of chemoattractant receptors.

[Evaluation of dynamic enhanced fast multiplanar spoiling gradient recalled(FMPSPGR) in the diagnosis of small hepatocellular carcinoma]

OBJECTIVE

To analyze the features of small hepotocellular carcinoma (SHCC) by spin echo (SE) sequence and dynamic enhanced FMPSPGR, and to compare the sensitivity for detecting and the accuracy for characterization, further to discuss the value of FMPSPGR in the diagnosis of SHCC.

METHODS

SE T(1)WI, T(2)WI and FMPSPGR dynamic imaging of the liver were performed for 58 patients with SHCC. The sensitivity for detecting and accuracy for characterization were statistically compared.

RESULTS

Seventy-two lesions were found in 58 patients. In the detection of SHCC, the order of the sensitivity was dynamic enhanced FMPSPGR>SE T(2)WI>no-enhanced FMPSPGR>SE T(1)WI. Dynamic enhanced FMPSPGR was significantly higher than any of the others. There was significant difference between no-enhanced FMPSPGR and SE T(2)WI, but not significant difference between T(2)WI and no-enhanced FMPSPGR. In the characterization of SHCC, the accuracy of pre- and post-contrast FMPSPGR was significantly higher than that of SE (T(1)WI+T(2)WI) with remarkable statistical difference.

CONCLUSIONS

FMPSPGR dynamic imaging is superior to SE in the detection and characterization of SHCC. The sensitivity for detecting and the accuracy for characterization will be improved when both FMPSPGR and SE are used.

Further characterization of apolipoprotein B genetic variations in Taiwanese

Apolipoprotein B (apoB, protein; APOB, gene) is the main protein component of low-density lipoprotein (LDL) and plays an important role in blood lipid metabolism. Previously, we have reported four APOB coding regions, 5' signal peptide, and 3' repeat sequence polymorphisms in our population. In this report, we further characterize other APOB genetic variations. The results illustrate that the mutation frequencies for Arg3500Gln (1/846 alleles), Arg4019Trp (2/786 alleles), -265 C/T promoter region (0/264 alleles), and intron 2 A/G (0/450 alleles) are very low. Our population showed a frequency of 68.9% for the B4311 Ser allele. The B4311 Asn allele was associated with a higher apoB level than the Ser group (p < 0.05) in normal controls. In the normal controls, a higher B4311 Asn/Asn genotype frequency was found in the group with total cholesterol (TC) > 200 mg/dL and apoB concentration > 85 mg/dL than in the group with a TC < 200 mg/dL and apoB < 85 mg/dL (p = 0.03 for TC comparison).

[Serum glutathione S-transferase in bromobenzene-induced acute hepato-toxicity in mice]

The activity of serum glutathione S-transferase (GST) was tested in bromobenzene-induced acute hepatotoxicity in mice. The data showed that a lot of small local necrosis in liver biopsy was observed and serum GST activity was increased after 2 h of treatment with bromobenzene (150 mg/kg i.p.) in mice. Serum alanine transaminase (ALT) activity was also gradually enhanced after 8 hours of treatment. The most obvious changes were at 16 hours of bromobenzene treatment, and serum GST activity was firstly restored to normal level after 24 hours of treatment. There were good positive correlations between serum GST, ALT, as well as serum GST and the changes on liver biopsy. Evaluating analysis of the diagnosis test showed that the sensitivity, specificity and accuracy was 89%, 75% and 82% in serum GST test, and 39%, 92% and 64% in serum ALT test respectively. The ROC work curve also demonstrated that serum GST was more sensitive and specific than serum ALT.

[Developmental toxicity of Al(NO3)3 on rat embryos]

The developmental toxicity and its mechanism of Al(NO3)3 on embryos in SD rats were studied. On the 9.5th day of gestation, the embryos were incubated in a whole-embryo culture system with Al(NO3)3 at concentrations of Al3+ from 0.6 to 9.0 micrograms/ml in culture media for 48 hrs. Viable embryos were evaluated by Brown's morphological scoring system, and the diameter of yolk sac, crown-rump, head length and the dry weight of embryos were measured. There was a dose-dependent relations of decreasing embryo development with increasing concentrations of Al3+. Yolk sac diameter, head length, dry weight and heart, forelimb as well as neural tube scores decreased significantly at 1.2 micrograms/ml (P < 0.05). When embryos were exposed to Al3+ at > or = 3.0 micrograms/ml, the embryonic development and morphological differentiation were obviously inhibited(P < 0.05); meanwhile, the incidence of dysmorphogenesis significantly increased, including neural tube defects and dorsiflexion teratogenesis. The results suggested that aluminum might be a developmental toxicant and dysmorphogenesis agent.

Deficient long-term synaptic depression in the rostral cerebellum correlated with impaired motor learning in phospholipase C beta4 mutant mice

Long-term depression (LTD) at parallel fibre-Purkinje cell synapse of the cerebellum is thought to be a cellular substrate for motor learning. LTD requires activation of metabotropic glutamate receptor subtype 1 (mGluR1) and its downstream signalling pathways, which invariably involves phospholipase Cbetas (PLCbetas). PLCbetas consist of four isoforms (PLCbeta1-4) among which PLCbeta4 is the major isoform in most Purkinje cells in the rostral cerebellum (lobule 1 to the rostral half of lobule 6). We studied mutant mice deficient in PLCbeta4, and found that LTD was deficient in the rostral but not in the caudal cerebellum of the mutant. Basic properties of parallel fibre-Purkinje cell synapses and voltage-gated Ca2+ channel currents appeared normal. The mGluR1-mediated Ca2+ release induced by repetitive parallel fibre stimulation was absent in the rostral cerebellum of the mutant, suggesting that their LTD lesion was due to the defect in the mGluR1-mediated signalling in Purkinje cells. Importantly, the eyeblink conditioning, a simple form of discrete motor learning, was severely impaired in PLCbeta4 mutant mice. Wild-type mice developed the conditioned eyeblink response, when pairs of the conditioned stimulus (tone) and the unconditioned stimulus (periorbital shock) were repeatedly applied. In contrast, PLCbeta4 mutant mice could not learn the association between the conditioned and unconditioned stimuli, although their behavioural responses to the tone or to the periorbital shock appeared normal. These results strongly suggest that PLCbeta4 is essential for LTD in the rostral cerebellum, which may be required for the acuisition of the conditioned eyeblink response.

Allogeneic peripheral blood stem cell transplantation for leukemia

OBJECTIVE

To observe engraftment kinetics, the incidence and severity of graft-versus-host disease (GVHD), and clinical outcome on 40 recipients undergoing allogeneic peripheral blood stem cell transplantation (allo-PBSCT).

METHODS

From June 1997 to May 1999, forty leukemia patients with a median age of 35 years underwent allo-PBSCT. PBSC were mobilized with G-CSF at a dose of 5 micrograms/kg s.c. every 12 hours for 5 days. A median of 7.7 (2.0-16.8) x 10(6) CD34+ cells/kg was infused into the recipients. Busulfan-cyclophosphamide (BU-CY) was used as the conditioning regimen. All patients received cyclosporine A and either methotrexate (n = 34) or methylprednisolone (n = 6) for GVHD prophylaxis.

RESULTS

Engraftment of neutrophils and platelets was achieved at a median of 13 days (9-28 days) and 12 days (7-60 days) respectively. Patients receiving > or = 4 x 10(6) CD34+ cells/kg or given G-CSF post transplant had significantly accelerated neutrophil and platelet engraftment. Acute GVHD occurred in 17 of 40 patients (42.5%), with grade II-IV acute GVHD in 10 patients (25%). Chronic GVHD developed in 21 (9 extensive, 12 limited) out of 30 evaluable patients (21/30, 70%) with a median follow up of 380 days (180-900 days). Transplant related mortality was 17.5% and the relapse rate was 10%. The probability of leukemia free survival at 3 years was 72.5%.

CONCLUSION

Allo-PBSCT can provide rapid hematopoietic reconstitution without an increased incidence of acute GVHD, but may be associated with a high risk of chronic GVHD.

Insulin-like growth factor-1 reduces postischemic white matter injury in fetal sheep

Insulin-like growth factor-1 (IGF-1) is known to be important for oligodendrocyte survival and myelination. In the current study, the authors examined the hypothesis that exogenous IGF-1 could reduce postischemic white matter injury. Bilateral brain injury was induced in near-term fetal sheep by 30 minutes of reversible carotid artery occlusion. Ninety minutes after ischemia, either vehicle (n = 8) or a single dose of 3 microg IGF-1 (n = 9) was infused intracerebroventricularly over 1 hour. White matter changes were assessed after 4 days recovery in the parasagittal intragyral white matter and underlying corona radiata. Proteolipid protein (PLP) mRNA staining was used to identify bioactive oligodendrocytes. Glial fibrillary acidic protein (GFAP) and isolectin B-4 immunoreactivity were used to label astrocytes and microglia, respectively. Myelin basic protein (MBP) density and the area of the intragyral white matter tracts were determined by image analysis. Insulin-like growth factor-1 treatment was associated with significantly reduced loss of oligodendrocytes in the intragyral white matter (P < 0.05), with improved MBP density (P < 0.05), reduced tissue swelling, and increased numbers of GFAP and isolectin B-4 positive cells compared with vehicle treatment. After ischemia there was a close association of PLP mRNA labeled cells with reactive astrocytes and macrophages/microglia. In conclusion, IGF-1 can prevent delayed, postischemic oligodendrocyte cell loss and associated demyelination.

Growth suppression activity of the PTEN tumor suppressor gene in human endometrial cancer cells

The AKT proteins are constitutively activated in several types of human cancers, which may play a role in carcinogenesis. In this study, we examined the activation of AKT in a panel of human endometrial cancer cell lines and tumor samples in this study. Two endometrial cancer cell lines, Ishikawa (ISK) and RL-95 and several tumor samples showed elevated levels of phosphorylated AKT PTEN, which is mutated in 45% of endometrial cancers, is a negative regulator of AKT. We examined the growth suppression activity of PTEN in ISK and KLE endometrial cancer cells. Expression of PTEN significantly suppressed the growth of both cell clines. In primary rat embryo fibroblasts, PTEN also inhibited malignant transformation mediated by ras and c-myc oncogenes. These two oncogenes are commonly mutated or amplified in endometrial cancer. These results suggest that PTEN may be a potent therapeutic agent for endometrial cancer.

Smads in human trophoblast cells: expression, regulation and role in TGF-beta-induced transcriptional activity

Smad proteins have recently been shown to be downstream signaling molecules that transduce TGF-beta signals from cell surface to the nucleus. To determine the mechanisms of TGF-beta action in human trophoblast cells, we investigated the expression and regulation of Smad2,3,4, and 7 mRNAs in a normal trophoblast cell line, NPC, and a cell line derived from choriocarcinoma, JEG-3. Messenger RNAs for Smad2,3,4 and 7 were detected in both NPC and JEG-3 cells. TGF-beta1 induced modest increases in Smad2 and Smad4 mRNA levels without affecting Smad3 mRNA expression in both cell lines. Significant increases in Smad7 mRNA levels in both NPC and JEG-3 cells following TGF-beta1 treatment were observed. TGF-beta1 also induced promoter activity of the Smad7 gene, indicating a direct effect at the level of gene transcription. The transcriptional activity of TGF-beta was examined in JEG-3 cells using two TGF-beta responsive reporter constructs, p3TP-Lux and pAR3-Lux. We found that Smad3 and to a lesser extent, Smad2 and Smad4, enhanced, while Smad7 inhibited, TGF-beta1-induced transcriptional activities. The basal and TGF-beta1-induced transcription can be blocked by overexpression of a dominant negative TGF-beta type II receptor. Taken together, these findings demonstrate that in human trophoblast cell lines, the Smad pathway involved in TGF-beta signal transduction is functional and that TGF-beta plays an autocrine role in regulating gene expression.

Removal of glutathione produces apoptosis and necrosis in HepG2 cells overexpressing CYP2E1

BACKGROUND

Previous studies have shown that addition of ethanol, iron, or arachidonic acid to HepG2 cells expressing CYP2E1 produced a loss in cell viability and caused apoptosis. These effects were enhanced when cellular reduced glutathione (GSH) levels were lowered by treatment with buthionine sulfoximine (BSO). Overexpression of CYP2E1 in HepG2 cells could produce toxicity even in the absence of added toxin after BSO treatment. Studies were carried out to characterize this CYP2E1-and BSO-dependent toxicity.

METHODS

HepG2 cells expressing CYP2E1 were treated with BSO for 1 to 4 days, and various parameters associated with apoptosis and cell viability were assayed.

RESULTS

Treatment of cells expressing CYP2E1 (E47 cells) with BSO resulted in apoptosis as well as necrosis. The apoptosis and necrosis were independent of each other. No toxicity was found with control HepG2 cells or HepG2 cells expressing CYP3A4 instead of CYP2E1 under these conditions. The antioxidant trolox partially prevented the apoptosis and necrosis, whereas diallylsulfide, a CYP2E1 inhibitor, was fully protective. The activity of caspase 3, but not caspases 1, 8, or 9, was increased in the BSO-treated E47 cells, and an inhibitor of caspase 3 prevented apoptosis. Damage to mitochondria appears to play a role in the CYP2E1- and BSO-dependent toxicity, because mitochondrial membrane potential was decreased and cyclosporin A, an inhibitor of the mitochondrial membrane permeability transition, prevented the apoptosis and the necrosis. The fall in membrane potential was prevented by trolox and diallylsulfide, suggesting damage to the mitochondria by CYP2E1-derived reactive oxygen species.

CONCLUSIONS

These results indicate the critical role of GSH in protecting against CYP2E1-mediated oxidative stress and that mitochondria may be a target for CYP2E1-derived reactive oxygen species, and suggest that interactions between CYP2E1, mitochondria, and altered GSH homeostasis may play a role in alcohol-induced liver injury.

Low-density lipoprotein receptor-related protein-5 binds to Axin and regulates the canonical Wnt signaling pathway

To understand how the Wnt coreceptor LRP-5 is involved in transducing the canonical Wnt signals, we identified Axin as a protein that interacts with the intracellular domain of LRP-5. LRP-5, when expressed in fibroblast cells, showed no effect on the canonical Wnt signaling pathway by itself, but acted synergistically with Wnt. In contrast, LRP-5 mutants lacking the extracellular domain functioned as constitutively active forms that bind Axin and that induce LEF-1 activation by destabilizing Axin and stabilizing beta-catenin. Addition of Wnt caused the translocation of Axin to the membrane and enhanced the interaction between Axin and LRP-5. In addition, the LRP-5 sequences involved in interactions with Axin are required for LEF-1 activation. Thus, we conclude that the binding of Axin to LRP-5 is an important part of the Wnt signal transduction pathway.

Sodium salicylate increases CYP2E1 levels and enhances arachidonic acid toxicity in HepG2 cells and cultured rat hepatocytes

Sodium salicylate and acetylsalicylic acid are drugs used as anti-inflammatory agents. Salicylate prevents nuclear factor-kappa B activation and can cause apoptosis. However, salicylate, a substrate of CYP2E1, is also an antioxidant and can scavenge reactive oxygen species. Experiments were carried out to evaluate whether salicylate can modulate CYP2E1-dependent toxicity. Addition of a polyunsaturated fatty acid such as arachidonic acid (AA) to HepG2 cells resulted in loss of cell viability, especially in cells expressing CYP2E1 (E47 cells). Toxicity was enhanced by the addition of 1 to 10 mM salicylate to the E47 cells but not to control HepG2 cells or HepG2 cells expressing CYP3A4. Salicylate alone was not toxic, and the enhanced toxicity by AA in the presence of salicylate was prevented by diallyl sulfide, a CYP2E1 inhibitor, and by the antioxidant (+/-)6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid. Salicylate potentiated AA-induced lipid peroxidation in the E47 cells, a reaction blocked by diallyl sulfide. CYP2E1 levels were elevated by salicylate at concentrations (<5 mM), which did not increase CYP2E1 mRNA levels. This increase was associated with a decrease of CYP2E1 turnover by salicylate in the presence of cycloheximide. Salicylate also potentiated AA toxicity in hepatocytes isolated from pyrazole treated rats with high levels of CYP2E1 and from saline controls. In view of the potential role of CYP2E1 in contributing to alcohol-induced oxidative stress and liver injury, the potentiation of CYP2E1-dependent toxicity and the elevation of CYP2E1 levels by salicylate may be of clinical significance and merit caution in the use of salicylate and salicylate precursors such as acetylsalicylic acid with certain other drugs.

[One stage otoplasty treatment for congenital malformations of the auricle and middle ear]

OBJECTIVE

To investigate the application of one stage otoplasty for congenital atresia of the external acoustic canal and malformations of the middle ear and the auricle.

METHOD

Patients with the ear malformations were given surgical reconstruction of one stage otoplasty. The auricle was reconstructed with the rib which was encapsulated with the superthin temporal flap. According to the malformations of the middle ear in patients, I style tympanoplasty and III style tympanoplasty were carried out respectively. All patients were performed myringoplasty with temporal fascia and reconstructed the external acoustic canal with full thickness skin-grafting.

RESULT

A long term follow-up (4-6 years) demonstrated that 11 ears were survival of which 8 ears figuration were ideal. The hearing improvement was observed in all patients.

CONCLUSION

One stage otoplasty is effective for treatment of the congenital malformations of the external and middle ear.

Human homologues of Delta-1 and Delta-4 function as mitogenic regulators of primitive human hematopoietic cells

Delta-mediated Notch signaling controls cell fate decisions during invertebrate and murine development. However, in the human, functional roles for Delta have yet to be described. This study reports the characterization of Delta-1 and Delta-4 in the human. Human Delta-4 was found to be expressed in a wide range of adult and fetal tissues, including sites of hematopoiesis. Subsets of immature hematopoietic cells, along with stromal and endothelial cells that support hematopoiesis, were shown to express Notch and both Delta-1 and Delta-4. Soluble forms of human Delta-1 (h Delta-1) and h Delta-4 proteins were able to augment the proliferation of primitive human hematopoietic progenitors in vitro. Intravenous transplantation of treated cultures into immune-deficient mice revealed that h Delta-1 is capable of expanding pluripotent human hematopoietic repopulating cells detected in vivo. This study provides the first evidence for a role of Delta ligands as a mitogenic regulator of primitive hematopoietic cells in the human. (Blood. 2001;97:1960-1967)