Biomedical subjects

B Li

Publications and source records attributed to B Li.

At least 469 records · Page 26Linked to original sources

PubMed1997

Isolation and characterization of the promoter region of the chicken N-cadherin gene.

N-cadherin (CDH2) is a member of the cadherin family of Ca2(+)-dependent cell-cell adhesion molecules. To investigate mechanisms controlling CDH2 transcription, we isolated and analyzed a genomic DNA sequence containing 2.8 kb of 5' flanking region and the first two exons of chicken CDH2. Sequence analysis of the promoter region of CDH2 revealed no CCATT or TATA boxes, but showed a high overall GC content, high CpG dinucleotide content, and several consensus Sp1 and Ap2 binding sequences. When fused to the cat reporter gene in transient transfection experiments, the sequence from positions -3231 to -118 (relative to the translation start site) directed high-level expression in CDH2-expressing chicken primary retinal cells and mouse N2A cells, but was much less active in chicken embryonic fibroblast cells and mouse 3T3 cells which do not express CDH2. Similarly, this promoter fragment directed variable, but neuronal-specific, expression of reporter genes in adult transgenic mice, but failed to produce the correct pattern of expression in other tissues, implying that additional sequences further upstream and/or within introns of CDH2 may play important roles in the transcriptional control.

3T3 Cells↗

PubMed1997

In vivo hyperexpression of transforming growth factor-beta1 in mice: stimulation by cyclosporine.

BACKGROUND: We have demonstrated that cyclosporine (CsA) stimulates transforming growth factor (TGF) beta1 expression in vitro and that growth of mammalian cells can be arrested by CsA via a TGF-beta1-dependent mechanism. Herein, we have explored whether CsA stimulates TGF-beta1 hyperexpression in vivo. METHODS: Four groups of B6AF1 mice were studied: group 1, control; group 2, CsA pretreatment; group 3, anti-CD3 monoclonal antibody pretreatment; and group 4, CsA plus anti-CD3 pretreatment. RESULTS: CsA pretreatment augmented TGF-beta1 protein expression and increased intrarenal display of TGF-beta1 mRNA. This heightened TGF-beta1 expression was associated with an impaired T cell proliferative response. CONCLUSIONS: Our observations, together, advance the hypothesis that CsA might function in vivo as an immunosuppressant not only by inhibiting the expression of proinflammatory cytokines (e.g., interleukin 2), but also by stimulating the expression of TGF-beta1, a potent immunosuppressive cytokine. Moreover, prevention of TGF-beta1 hyperexpression might prevent CsA-associated renal fibrosis, as TGF-beta1 is a fibrogenic cytokine.

Animals↗

PubMed1997

Angiotensin II activates programmed myocyte cell death in vitro.

To determine whether angiotensin II (Ang II) can induce apoptosis of neonatal ventricular myocytes, these cells were exposed to 10(-9) M Ang II for 24 h in vitro and the effects of this intervention on programmed myocyte cell death were examined by the terminal deoxynucleotidyl transferase assay and DNA gel electrophoresis. Ang II resulted morphologically in a 2.5-fold increase in the percentage of myocytes with double strand cleavage of the DNA and biochemically in the formation of DNA fragments equal in size to mono- and oligonucleosomes. Moreover, Ang II stimulation was characterized by a 37% increase in resting level of intracellular calcium and the activation of calcium-dependent endogenous endonuclease. In contrast, pH-dependent endogenous endonuclease was not enhanced by the addition of Ang II. Ang II-induced DNA damage was inhibited by the AT1 receptor antagonist, losartan. Similarly, the calcium chelator, BAPTA-AM, prevented Ang II-mediated cell death. Conversely, the calcium ionophore, A23187, triggered programmed cell death. Finally, the selective AT2 receptor subtype blocker, PD123319, failed to reduce myocyte apoptosis. In conclusion, ligand binding of AT1 receptors may initiate programmed myocyte cell death via an elevation in cytosolic calcium and the stimulation of calcium-dependent endogenous endonuclease.

Angiotensin II↗

PubMed1997

The thermodynamic advantage of DNA oligonucleotide 'stacking hybridization' reactions: energetics of a DNA nick.

'Stacking hybridization reactions' wherein two or more short DNA oligomers hybridize in a contiguous tandem orientation onto a longer complementary DNA single strand have been employed to enhance a variety of analytical oligonucleotide hybridization schemes. If the short oligomers anneal in perfect head-to-tail register the resulting duplex contains a nick at every boundary between hybridized oligomers. Alternatively, if the short oligomers do not hybridize precisely in register, i.e. single strand regions on the longer strand are left unbound, gaps are formed between regions where short oligomers bind. The resulting gapped DNA duplexes are considerably less stable than their nicked duplex analogs. Formation of base pair stacking interactions between neighboring oligomers at the nicks that do not occur in gapped duplexes has been proposed as the source of the observed added stability. However, quantitative evidence supporting this hypothesis for DNA has not been reported. Until now, a direct comparison of the thermodynamics of DNA nicks versus DNA gaps has not been performed. In this communication we report such a comparison. Analysis of optical melting experiments in a well defined molecular context enabled quantitative evaluations of the relative thermodynamic difference between nicked and gapped DNA duplexes. Results of the analysis reveal that a nick may be energetically favored over a gap by at least 1.4 kcal/mol and perhaps as much as 2.4 kcal/mol. The presence of a 5'phosphate at a nick or gap fails to significantly affect their stabilities.

DNA↗

PubMed1997

Glucose-responsitivity and expression of an ATP-stimulatable, Ca(2+)-independent phospholipase A2 enzyme in clonal insulinoma cell lines.

We have previously reported that pancreatic islet beta-cells and clonal HIT insulinoma cells express an ATP-stimulatable Ca(2+)-independent phospholipase A2 (ASCI-PLA2) enzyme and that activation of this enzyme appears to participate in glucose-stimulated insulin secretion. To further examine this hypothesis, glucose-responsitivity and expression of ASCI-PLA2 activity in various insulinoma cell lines were examined. Secretagogue-stimulated insulin secretion was observed with beta TC6-f7 and early passage (EP)-beta TC6 cells. In contrast, RIN-m5f, beta TC3, and late passage (LP)-beta TC6 cells exhibited little secretagogue-induced secretion. A haloenollactone suicide substrate (HELSS) which inhibits ASCI-PLA2 activity ablated secretagogue-induced insulin secretion from beta TC6-f7 and EP-beta TC6 cells. All insulinoma cell lines studied expressed both cytosolic and membrane-associated Ca(2+)-independent PLA2 activities which were inhibited by HELSS. The cytosolic enzymatic activity in the glucose-responsive beta TC6-f7 and EP-beta TC6 cells was activated by ATP and protected against thermal denaturation by ATP, but this was not the case in the glucose-unresponsive RIN-m5f, beta TC3, or LP-beta TC6 cells. Comparison of the distribution of Ca(2+)-independent PLA2 activity revealed that membrane-associated activity was higher than cytosolic activity in beta TC6-f7 and EP-beta TC6 cells but not in RIN-m5f, beta TC3, or LP-beta TC6 cells. Insensitivity of cytosolic activity to ATP may prevent association of the PLA2 activity with membrane substrates and contribute to attenuated glucose-responsitivity in the RIN-m5f, beta TC3, or LP-beta TC6 cells. HIT insulinoma cells were also found to undergo a decline in both glucose-responsitivity and membrane-associated Ca(2+)-independent PLA2 activity upon serial passage in culture, and this was associated with a reduction in membrane content of arachidonate-containing phospholipids. These and previous results suggest that the ATP-stimulatable PLA2 enzyme may participate in glucose-induced insulin secretion.

Adenosine Triphosphate↗

PubMed1997

A yeast artificial chromosome (YAC) contig encompassing the critical region of the X-linked lymphoproliferative disease (XLP) locus.

X-linked lymphoproliferative disease (XLP) is characterized by a marked vulnerability to Epstein-Barr virus (EBV) infection. Infection of XLP patients with EBV invariably results in fatal mononucleosis, agammaglobulinemia, or malignant lymphoma. Initially the XLP gene was assigned to a 10-cM region in Xq25 between DXS42 and DXS37. Subsequently, an interstitial, cytogenetically visible deletion in Xq25 was identified in one XLP family, 43. In this study we estimated the deletion in XLP patient 43-004 by dual-laser flow karyotyping to involve 2% of the X chromosome, or approximately 3 Mb of DNA sequence. From a human chromosome Xq25-specific yeast artificial chromosome (YAC) sublibrary, five YACs containing DNA sequences deleted in patient 43-004 have been isolated. Sequence-tagged sites (STSs) from these YACs have been used to identify interstitial deletions in unrelated XLP patients. Three more families with interstitial deletions were found. Two of the patients (63-003 and 73-032) carried an interstitial deletion of 3.0 Mb overlapping the 43-004 deletion. In one XLP patient (30-011) who exhibited the characteristic postinfectious mononucleosis phenotype of XLP with hypogammaglobulinemia and malignant lymphoma, a deletion of approximately 250 kb was detected overlapping the deletion detected in patients 43-004, 63-003, and 73-032. A YAC contig of 2.2 Mb spanning the XLP critical region, whose orientation on chromosome X was determined by double-color fluorescence in situ hybridization and which consists of 15 overlapping YAC clones, has been constructed. A detailed restriction enzyme map of the region has been constructed. YAC insert sizes were determined by counter-clamped homogenous electric field gel electrophoresis. Chimerism of YACs was determined by FISH and restriction mapping. On the basis of lambda subclones, YAC end-derived plasmids, and STSs with an average spacing of 100 kb, a long-range physical map was constructed using 5 rare-cutter restriction enzymes. The STSs and lambda subclones were used in Southern hybridization and PCR analyses. The work presented here substantially refines the critical region for XLP. The YAC contig with the overlapping interstitial deletions constitutes the basis for the construction of a transcriptional map of the critical region and facilitates the identification of the XLP gene.

Chromosomes, Artificial, Yeast↗

PubMed1997

Effect of sialoadenectomy and epidermal growth factor administration on liver regeneration after partial hepatectomy.

Epidermal growth factor (EGF), a mitogen in vitro for hepatocytes, produces in various cell lines changes similar to those observed very rapidly in hepatocytes after partial hepatectomy (PH). These changes include ion movements, membrane hyperpolarization and proto-oncogene expression. A stimulatory effect of EGF on liver regeneration can therefore tentatively be associated with the events occurring within the first 3 hours after a PH, sometimes referred to as the "priming phase." To assess this hypothesis, we examined in Wistar rats the effect of EGF deprivation produced by sialoadenectomy (SX) performed before or after a PH of 70%. SX at the time of PH significantly decreased the 3H-thymidine uptake in the DNA 24 hours later (147 +/- 14 DPM per microgram of DNA, mean +/- SE) compared with a simple PH (322 +/- 16; P < .01), but also compared with results obtained when PH is combined with a sham sialoadenectomy (SSX) or in rats pair-fed with the sialoadenectomized rats. This incomplete inhibition was confirmed by a decreased rise in thymidine kinase (TK) activity and by reduced proliferating cell nuclear antigen (PCNA) labeling and mitotic indices 30 hours after PH. By contrast, SX did not inhibit the early expression of c-jun and c-fos, or of c-myc, 30 or 120 minutes after PH, respectively. A reduction of DNA synthesis was also obtained when SX was performed 3 hours after PH (127 +/- 15 DPM per microgram of DNA vs. 350 +/- 21 in SSX; P < .001) but not when SX was delayed until the 6th or the 17th hour after PH. It was sufficient to administer EGF (40 microg) from the third to the ninth hour to correct the reduction of [3H]thymidine uptake in rats sialoadenectomized before PH. These results indicate that the diminished EGF availability following SX decreases or at least delays liver regeneration, and that the effect of EGF on liver regeneration does not seem related to the early changes of proto-oncogene expression, but rather to events occuring later, at the time of reported internalization and binding of EGF to its nuclear receptors.

Animals↗

PubMed1997

In vitro studies of spontaneous and corticosteroid-induced apoptosis of lymphocyte populations from metamorphosing frogs/RU486 inhibition.

Metamorphosis in the South African clawed frog, Xenopus laevis, results in significant changes in the immune system. It is characterized by a striking involution of the thymus and spleen followed by lymphocyte expansion in the postmetamorphic period. While thyroid hormones are generally thought to be the most important mediators of morphological changes during metamorphosis, corticosteroid hormones (CH) have also been shown to accelerate metamorphic changes. We have been studying the possible role of CH as effectors of changes in the immune system at metamorphosis. Because CH induce apoptosis of developing murine thymocytes, we examined in vitro levels of spontaneous and CH-inducible apoptosis of lymphocyte populations removed from the thymus and spleen of tadpoles before metamorphosis, during the period of naturally elevated corticosteroids at the climax of metamorphosis, and from postmetamorphic adults. We show here that spontaneous apoptosis of splenocytes or thymocytes measurable at the time of sacrifice or after culture for 24 h at 4 degrees C is very low at all stages of development and is not increased at metamorphosis. Apoptosis induced by culture of lymphocytes for 24 h at 26 degrees C in 10 nM corticosterone (well below the peak level of 70 nM found at climax of metamorphosis) ranges from about 30-50% in the splenocyte population and 55-70% in the thymocyte population. Using the corticosteroid hormone receptor antagonist, RU486, we separated the CH-dependent component of apoptosis from apoptosis due to other factors. In the spleen, about 12-23% of lymphocytes are susceptible to corticosteroid-induced apoptosis at all larval stages as well as during climax of metamorphosis as measured by this short term culture assay. Another approximately 15% of cells undergo spontaneous apoptosis which is independent of CH. Although dissociated thymocytes exhibit very high levels of apoptosis (55-75%) during culture at 26 degrees C for 24 h, most of the apoptosis is independent of CH and may result from loss of "survival signals" due to the disruption of the thymic microenvironment. These studies support the hypothesis that naturally elevated levels of endogenous free CH delete a significant proportion of the larval splenocyte population during climax of metamorphosis by induction of apoptosis. This clearing of lymphocytes may prevent destructive autoimmune responses to the new set of adult-specific antigens that emerges at metamorphosis.

Animals↗

PubMed1997

Ischemia induces significant changes in purine nucleoside concentration in the retina-choroid in rats.

Adenosine, produced from the decomposition of adenosine triphosphate, is believed to provide protective effects during ischemia. On the other hand, adenosine metabolites may serve as precursors for oxygen free radical formation. The time course of formation of adenosine and its purine metabolites was studied during retinal ischemia in rats. Concentrations of adenosine and its purine nucleoside metabolites inosine, hypoxanthine, and xanthine in the retina-choroid of ketamine/xylazine-anesthetized rats were measured during retinal ischemia using high performance liquid chromatography. Quantitative measurements were made possible in the small tissue mass through the use of internal standards. Ischemia was induced by ligation of the central retinal artery. In each rat, one eye was ischemic while the other served as a non-ischemic control. Eyes were frozen in situ at 1, 5, 10, 20, 30, 60, and 120 min of ischemia. The retina-choroid was then removed from the frozen eyes and analysed. Significant increases in the concentrations of adenosine, inosine, and hypoxanthine in ischemic compared to control retina-choroid were detectable within 1 to 5 min of the onset of ischemia, and within 10 min for xanthine. Increase in adenosine concentration in ischemic relative to control retina-choroid plateaued at 30 min of ischemia, while inosine and hypoxanthine concentrations increased continuously. The increase in xanthine concentration was exponential throughout the measurement period. This study documented the time-related changes in purine nucleoside concentration during ischemia. Prolonged ischemia results in ongoing production of xanthine, which by serving as a precursor for oxygen free radical formation, could be a pathogenic factor in prolonged retinal ischemia.

Adenosine↗

PubMed1997

Detection and characterization of the fimA gene of Escherichia coli O157:H7.

An expected 850-bp DNA fragment containing fimA, the structural gene for type 1 fimbriae, and flanking sequences was amplified from 39 (of 46) pathogenic and commensal strains of Escherichia coli using the polymerase chain reaction (PCR). Restriction fragment length polymorphism (RFLP) analysis of the amplified products showed 13 HinP1 and four Sau961 restriction profiles among these 39 E. coli strains, revealing the polymorphic nature of this allele. A unique RFLP pattern was shared by E. coli O157:H7, O157:H- and a few O55 serotype strains. DNA sequence analysis of the fimA region demonstrated that E. coli O157:H7 strain 933 and O157:H- strain E32511 contained identical DNA sequences that were distinct from other E. coli strains, especially a 16-bp sequence 5' to fimA that was conspicuously absent only in E. coli O157 strains. Exploiting these differences, a PCR assay was developed that amplifies a 936-bp fragment from all E. coli O157:H7 strains examined to date. This PCR assay offers a simple, rapid, and reliable means to detect E. coli strains of the O157:H7 serotype.

Amino Acid Sequence↗

PubMed1997

Material properties of bone from the femoral neck and calcar femorale of patients with osteoporosis or osteoarthritis.

Patients with osteoarthritis (OA) rarely fracture the neck of the femur whereas this is common in patients with osteoporosis (OP). The reasons for this are not clear. In this study, cores of trabecular bone and thin slices of bone from the calcar were obtained from the femoral neck of patients with OA or OP following hip arthroplasty and a normal group post mortem. The mechanical properties, densities and material composition were measured. The aim was to determine whether differences in these properties could explain why osteoarthritic patients did not suffer from fractured neck of femur. No difference was found in the density or stiffness of the calcar between the groups, though there appeared to be a small increase in mineralization in the OA bone compared with the OP. However, there was a 72% increase in the volume of trabecular bone in the OA group compared with a loss of about 20% in the OP group. This increased apparent density of the OA trabecular bone resulted in a greater stiffness, yield strength and energy absorbed to yield, whereas the same properties of OP bone were not significantly lower than normal. These marked changes in the OA bone could result in a redistribution of stresses due to loads caused by falling, thereby absorbing the energy of impact and preventing the formation of a fracture surface.

Aged↗

PubMed1997

Th2-like response and antitumor effect of anti-interleukin-4 mAb in mice bearing renal cell carcinoma.

Tumor regression in experimental systems has been linked to the activities of Th1 cells. It is, therefore, conceivable that Th2 cells interrupt the expression of tumor immunity since interleukin-4 (IL-4) and IL-10 inhibit the generation of Th1 from precursors and modulate the competence of antigen-presenting cells to activate this lymphocyte subpopulation. Naive murine renal cell carcinoma (renca) cells (1 x 10(5)) were implanted into the subcapsule of the left kidney of Balb/c and Balb/c nude mice at 6-8 weeks of age. After 14 days, Th2 cytokine (IL-4 and IL-10) mRNAs as well as transforming growth factor beta1 mRNA, assessed by reverse transcriptase/polymerase chain reaction were upregulated in the spleen of hosts upon naive renca tumor acceptance, while Th1 cytokine (IL-2 and interferon gamma) mRNAs were almost undetectable. In the renca tumor, IL-10 mRNA was detected but IL-2, interferon gamma, and IL-4 were not. Intraperitoneal administration of anti-(mouse IL-4) mAb (11B11) reduced the renca tumor size (P = 0.018) and prolonged host survival (P = 0.03), but did not reduce the acceptance rate of the tumor (P = 0.18). However, prior depletion of CD4+ or CD8+ cells with monoclonal antibodies abrogated the antitumor effects of anti-IL-4 mAb. In addition, the significant antitumor effect of anti-IL-4 mAb was not observed in Balb/c nude hosts. Renca cells were transfected with the mammalian expression vector pCAGGS containing murine IL-4 cDNA or vector alone, then stable IL-4 transfectants (RencaL or RencaH, low- or high-IL-4-producing respectively) and control renca cells (RencaC) were obtained. RencaL cells, RencaH cells, or RencaC cells (1 x 10(5) each) were implanted into the subcapsule of the left kidney of Balb/c, Balb/c nude, and allogenic C3H/HeJ mice, then tumor formation was evaluated 14 days later. When RencaH cells were innoculated into syngeneic Balb/c hosts, tumor volume was marginally suppressed (P = 0.03) and tumors tended to be rejected (P = 0.06) compared with RencaC cells. However, those effects were not observed in Balb/c nude mice. RencaC, RencaL, and RencaH cells were not accepted by allogeneic C3H mice with or without FK506 administration or donor-specific transfusion. The administration of anti-(mouse IL-4) mAb to Balb/c mice significantly suppressed renca tumor growth by a CD4+ and CD8+ T-cell-dependent mechanism. By contrast, relatively high levels of IL-4 production by renca cells and T cells seemed to be required to induce the rejection and growth suppression of IL-4-producing renca cells in syngeneic hosts.

Animals↗

PubMed1997

Coronary artery stenosis in rats affects beta-adrenergic receptor signaling in myocytes.

OBJECTIVE: The purpose of this study was to determine whether the early chronic ischemic cardiomyopathy produced by non-occlusive coronary artery constriction was characterized by alterations in the regulation of beta-adrenoreceptor (beta-AR) signaling. METHODS: Coronary artery narrowing was surgically induced in rats and the animals sacrificed at 7 and 14 days. The changes in the biochemical properties of the multiple components of the beta-AR pathway were examined in enzymatically dissociated myocytes. RESULTS: Coronary stenosis, involving an average 55% reduction in luminal diameter, was associated with left ventricular failure and right ventricular dysfunction at both time intervals. A decrease in the quantity of beta-AR was detected at 7 days and preceded the loss of high-affinity binding sites. This regulatory modification was characterized by a reduction in beta 1 and beta 2 receptors and a shift in the isoproterenol dose response curve indicating a functional correlation between the decrease in beta-AR and attenuated inotropic support of the myocardium. The percentage of beta-AR binding agonist with high affinity decreased significantly at 14 days along with a further reduction in the density of beta 1 and beta 2 receptors. Reconstitution studies with cyc S49 lymphoma cells did not detect an impairment of Gs alpha functional activity, but the quantity of Gi alpha was increased at both intervals. Finally, activation of the catalytic unit of adenylyl cyclase by forskolin and GTP was not altered by coronary stenosis, however, basal cyclic AMP in myocytes was depressed at 14 days. CONCLUSIONS: Coronary stenosis induces distinct and progressive modifications in the beta-AR signaling cascade which may contribute to the impaired ventricular performance in this model of myocardial ischemia.

Adrenergic beta-Agonists↗

PubMed1997

Immunostimulatory therapy with anti-CD3 monoclonal antibodies and recombinant interleukin-2: heightened in vivo expression of mRNA encoding cytotoxic attack molecules and immunoregulatory cytokines and regression of murine renal cell carcinoma.

The response rate to IL-2 immunotherapy, currently used in the treatment of metastatic renal cell cancer, is limited. Based on our earlier demonstration that a combined regimen of monoclonal antibodies directed at the T cell surface protein CD3 (anti-CD3 mAbs) and IL-2 is synergistic in constraining tumor progression in a murine fibrosarcoma hepatic metastasis model, we have explored the efficacy of an anti-CD3 mAbs plus IL-2 regimen in a murine renal cell cancer model. Our studies demonstrate that a regimen of anti-CD3 mAbs plus IL-2 is superior to treatment with anti-CD3 mAbs alone or IL-2 alone in reducing the number of pulmonary metastases and in prolonging survival. Moreover, the efficacious regimen is associated with heightened intrapulmonary expression of mRNA encoding cytotoxic attack molecules (perforin, granzyme B) and immunoregulatory cytokines (IL-4, IL-10 and IFN- gamma).

Animals↗

PubMed1997

Uptake and efflux of intact antisense phosphorothioate deoxyoligonucleotide directed against angiotensin receptors in bovine adrenal cells.

Antisense oligonucleotide (AS-ODN) inhibition of angiotensin receptors (AT1-R) offers a potentially novel therapeutic approach for hypertension, left ventricular hypertrophy and other aspects of cardiovascular disease. To clarify questions concerning cellular uptake and retention of these oligos, we quantified the trafficking and stability of phosphorothioated modified AS-ODN to AT1 receptor mRNA in adrenal cells, using visual and chromatographic analysis. The AS-ODN to AT1 receptor mRNA was effective in significantly inhibiting AT1 receptor binding in a dose dependent manner. FITC-labeled ODNs were used to determine the cellular uptake in bovine adrena cortex cells; using confocal microscopy, rapid cellular uptake of 15-mer ODNs was observed. Uptake is initially rapid (30 min to 4 h) followed by a slower uptake process 24 h and after. The cellular accumulation of ODN involves a dynamic balance between influx and efflux processes. Efflux of FITC-ODN had a f1/2 = 4.6 days. Uptake was time and dose dependent. No obvious degradation of intracellular ODNs occurred as shown by intact peaks for 15-mer ODN on thin layer chromatography. The results suggest that the AS-ODN to AT1 receptor mRNA was resistant to cellular nucleases. The FITC-ODN accumulated mainly in the nucleus and remained there intact for up to 3 days. No significant change in target mRNA was observed by quantitative RT-PCR. Therefore the antisense inhibition mechanism of this ODN does not appear to stimulate RNase H or block transcription. Since the ODN accesses the nucleus, the results imply that the ODN inhibits specific mRNA transport into the cytoplasm. The data show that AS-ODN, for inhibition of AT1 receptors, is rapidly taken up and stable in cells and produces specific inhibition of AT1 receptors.

Adrenal Cortex↗

PubMed1997

Angiographic study of moyamoya disease and histological study in the external carotid artery system.

A total of 13 cases of Moyamoya disease were verified by internal and external carotid artery angiography. The biopsy samples were taken from the superficial temporal arteries and middle meningeal arteries in 12 and six cases, respectively. Angiographical and histological studies revealed that both of the internal and external carotid system could be involved in Moyamoya disease. Our studies demonstrated that Moyamoya disease was a type of vascular disease not only confined to the cerebral vessels. We recommend angiography of external carotid system and extracranial segment of internal carotid artery while performing three vascular angiography. Whether superficial temporal artery has been involved in angiography can be used as an indication of indirect cerebrovascular bypass.

Biopsy↗

PubMed1997

Evaluation of properties of apigenin and [G-3H]apigenin and analytic method development.

This study provides baseline data and analytical methods to assist in the evaluation of apigenin, a plant flavonoid with promising chemopreventive activity against skin cancer. Apigenin was freely soluble in dimethylsulfoxide (> 100 mg/mL), but it had low solubility (0.00135-1.63 mg/mL) in all the other solvents and surfactants tested, especially in highly hydrophilic or nonpolar solvents. The partition coefficient (log K) calculated from the solubility ratio of apigenin in n-octanol and water was 2.87. Apigenin strongly absorbed UV light, with three maximum absorption wavelengths at 212, 269, and 337 nm (epsilon = 29,800, 19,020, and 18,930 M-1 cm-1, respectively). Using quercetin as the internal standard, a reversed-phase HPLC method was developed to quantitatively analyze apigenin in epidermal cells obtained from SENCAR mice. Apigenin was labeled at position 6, 8, 3', and 5' with tritium by a platinum-catalyzed proton-tritium exchange as confirmed indirectly by 1H NMR analysis of the deuterated apigenin. The tritium label was stable in aqueous environments, especially under acidic and neutral conditions, so [G-3H]apigenin was considered suitable for subsequent absorption and metabolic studies.

Animals↗

PubMed1997

Catecholamine modulatory effects of nepicastat (RS-25560-197), a novel, potent and selective inhibitor of dopamine-beta-hydroxylase.

1. Inhibitory modulation of sympathetic nerve function may have a favourable impact on the progression of congestive heart failure. Nepicastat is a novel inhibitor of dopamine-beta-hydroxylase, the enzyme which catalyses the conversion of dopamine to noradrenaline in sympathetic nerves. The in vitro pharmacology and in vivo catecholamine modulatory effects of nepicastat were investigated in the present study. 2. Nepicastat produced concentration-dependent inhibition of bovine (IC50 = 8.5 +/- 0.8 nM) and human (IC50 = 9.0 +/- 0.8 nM) dopamine-beta-hydroxylase. The corresponding R-enantiomer (RS-25560-198) was approximately 2-3 fold less potent than nepicastat. Nepicastat had negligible affinity (> 10 microM) for twelve other enzymes and thirteen neurotransmitter receptors. 3. Administration of nepicastat to spontaneously hypertensive rats (SHRs) (three consecutive doses of either 3, 10, 30 or 100 mg kg-1, p.o.; 12 h apart) or beagle dogs (0.05, 0.5, 1.5 or 5 mg kg-1, p.o.; b.i.d., for 5 days) produced dose-dependent decreases in noradrenaline content, increases in dopamine content and increases in dopamine/noradrenaline ratio in the artery (mesenteric or renal), left ventricle and cerebral cortex. At the highest dose studied, the decreases in tissue noadrenaline were 47%, 35% and 42% (in SHRs) and 88%, 91% and 96% (in dogs) in the artery, left ventricle and cerebral cortex, respectively. When tested at 30 mg kg-1, p.o., in SHRs, nepicastat produced significantly greater changes in noradrenaline and dopamine content, as compared to the R-enantiomer (RS-25560-198), in the mesenteric artery and left ventricle. 4. Administration of nepicastat (2 mg kg-1, b.i.d, p.o.) to beagle dogs for 15 days produced significant decreases in plasma concentrations of noradrenaline and increases in plasma concentrations of dopamine and dopamine/noradrenaline ratio. The peak reduction (52%) in plasma concentration of noradrenaline and the peak increase (646%) in plasma concentration of dopamine were observed on day-6 and day-7 of dosing, respectively. 5. The findings of this study suggest that nepicastat is a potent, selective and orally active inhibitor of dopamine-beta-hydroxylase which produces gradual modulation of the sympathetic nervous system by inhibiting the biosynthesis of noradrenaline. This drug may, therefore, be of value in the treatment of cardiovascular disorders associated with over-activation of the sympathetic nervous system, such as congestive heart failure.

Animals↗