Biomedical subjects

Z Mi

Publications and source records attributed to Z Mi.

At least 37 records · Page 2Linked to original sources

PubMed2000

Local and systemic effects of peritoneal lavage with high concentrations of adenosine in rats.

BACKGROUND: Adenosine exerts actions which may be beneficial in treating diseases of the gastrointestinal tract. However, administered systemically, adenosine causes a 'stress reaction' and may adversely affect blood pressure and cardiac and renal function. AIM: To determine whether peritoneal lavage with adenosine provides pharmacological levels of adenosine in the intestines without elevating adenosine levels in the systemic circulation. METHODS: Rats received an intramesenteric artery infusion of angiotensin II (30 ng/min) plus methoxamine (3 microg/min) to reduce mesenteric blood flow by approximately 60%, and adenosine solutions were instilled into the abdominal cavity. In a second study, microdialysis probes were placed in the mesenteric vein and aortic arch of rats, and the peritoneal cavity was continuously lavaged with adenosine solutions. RESULTS: High concentrations (10(-3)M) of adenosine normalized the mesenteric blood flow without affecting blood pressure or heart rate. High concentrations of adenosine (10(-3)M) induced micromolar levels of adenosine and inosine in the mesenteric vein, without affecting adenosine or inosine levels in the aorta. CONCLUSIONS: Peritoneal lavage with high concentrations of adenosine provides pharmacological levels of adenosine in the gastrointestinal tract without systemic side-effects. Peritoneal lavage with high concentrations of adenosine may be useful for the treatment of a number of diseases of the gastrointestinal tract.

Adenosine↗

PubMed2000

Potential of gene therapy for treating osteogenesis imperfecta.

Osteogenesis imperfecta is a heterogeneous group of genetic disorders that affect connective tissue integrity, with bone fragility being the major clinical feature. Most forms of osteogenesis imperfecta are the result of mutations in the genes that encode the pro alpha1 and pro alpha2 polypeptide chains of Type I collagen. Because osteogenesis imperfecta is an incurable genetic disease, cell therapy and gene therapy are being investigated as potential treatments. Gene therapy for osteogenesis imperfecta however is a major challenge; because most of the mutations in osteogenesis imperfecta are dominant negative, supplying the normal gene without silencing the abnormal gene may not be beneficial. Null mutations in which an allele is not expressed or absent may be amenable to gene therapy or alternatively after silencing a mutant allele, a normal gene could be supplied. In addition, overexpression of the normal collagen gene in cells expressing mutant collagen polypeptide chains potentially could lead to synthesis of a sufficient percentage of normal molecules to normalize clinical status. The authors currently are examining the possibility of developing gene therapy for treating a mouse model of human osteogenesis imperfecta (oim) using bone marrow stromal cells as vehicles for delivering normal collagen genes to bone. In the current study, the potential of gene therapy for treating osteogenesis imperfecta is discussed in the context of the complexity of the mutations in Type I collagen genes that lead to different osteogenesis imperfecta phenotypes.

Animals↗

PubMed2000

Using gene therapy to protect and restore cartilage.

Numerous gene products have the potential to help protect cartilage from degradation and to repair cartilage that has become damaged as a result of disease or injury. The genes that encode these products thus may serve as chondroprotective and chondroregenerative medicines. To bring these agents into clinical use, it is necessary to screen candidate genes for efficacy under in vitro and in vivo conditions, to determine the best cells to target, and to develop appropriate gene transfer technologies. As discussed in the current review, progress has been made in each of these areas. Various viral and nonviral vectors are able to deliver genes to synoviocytes, articular chondrocytes, and mesenchymal stem cells. There also is evidence to suggest that ex vivo and in vivo approaches can be used for gene transfer to articular cartilage, synovium, and meniscus. Moreover various cytokine antagonists and growth factors have been shown to protect cartilage and stimulate chondrogenesis. In vivo methods and strategies that target synovium may be useful in a chondroprotective mode but because they do not increase the number of chondrogenic cells within lesions, they may be ill-equipped to repair large defects. Ex vivo methods however, provide cells and genes. It also is important to distinguish the treatment of isolated lesions occurring as a result of injury from the treatment of lesions resulting from underlying disease processes. Additional development of these approaches should result in clinically useful genetic methods for the protection and regeneration of cartilagenous tissues.

Animals↗

PubMed2000

Estradiol inhibits smooth muscle cell growth in part by activating the cAMP-adenosine pathway.

Estradiol inhibits smooth muscle cell growth; however, the mechanisms involved remain unclear. Because estradiol stimulates cAMP synthesis and adenosine inhibits cell growth, we hypothesized that the conversion of cAMP to adenosine (ie, the cAMP-adenosine pathway) mediates in part the inhibitory effects of estradiol on vascular smooth muscle cell growth. To test this hypothesis, we examined the effects of estradiol (0.001 to 1 micromol/L) on serum-induced DNA, collagen, and total protein synthesis and cell number in the absence and presence of 1, 3-dipropyl-8-p-sulfophenylxanthine (10 nmol/L; A(1)/A(2) adenosine receptor antagonist), KF17837 (10 nmol/L; selective A(2) adenosine receptor antagonist), 8-cyclopentyl-1,3-dipropylxanthine (10 nmol/L; selective A(1) adenosine receptor antagonist), and 2', 5'-dideoxyadenosine (10 micromol/L; adenylyl cyclase inhibitor). Estradiol inhibited all measures of cell growth, and the concentration-dependent inhibitory curves for estradiol were shifted to the right (P<0.05) by 1,3-dipropyl-8-p-sulfophenylxanthine, KF17837, and 2',5'-dideoxyadenosine but not by 8-cyclopentyl-1, 3-dipropylxanthine. Moreover, the inhibitory effects of estradiol were enhanced by stimulation of adenylyl cyclase with forskolin and by inhibition of adenosine metabolism with erythro-9-(2-hydroxy-3-nonyl)adenine plus iodotubericidin (adenosine deaminase and kinase inhibitors, respectively). Estradiol also increased levels of cAMP and adenosine, and these effects were blocked by 2',5'-dideoxyadenosine (P<0.05). Our results support the hypothesis that estradiol stimulates cAMP synthesis and cAMP-derived adenosine regulates smooth muscle cell growth via A(2) adenosine receptors. Thus, the cAMP-adenosine pathway may contribute importantly to the antivasooclusive effects of estradiol.

Adenosine↗

PubMed2000

Cardiac fibroblasts express the cAMP-adenosine pathway.

The extracellular "cAMP-adenosine pathway" refers to the local production of adenosine mediated by cAMP egress into the extracellular space, conversion of cAMP to AMP by ectophosphodiesterase, and the metabolism of AMP to adenosine by ecto-5'-nucleotidase. The goal of this study was to assess whether the cAMP-adenosine pathway limits cardiac fibroblast growth. Studies were conducted in ventricular cardiac fibroblasts maintained in 3-dimensional cultures. Addition of exogenous cAMP to cardiac fibroblasts increased extracellular levels of AMP, adenosine, and inosine in a concentration-dependent and time-dependent manner. This effect was attenuated by blockade of total phosphodiesterase activity (3-isobutyl-1-methylxanthine), ectophosphodiesterase activity (high concentration of 1, 3-dipropyl-8-p-sulfophenylxanthine), or ecto-5'-nucleotidase (alpha, beta-methylene-adenosine-5'-diphosphate). Treatment with exogenous cAMP inhibited cell growth as assessed by DNA synthesis ((3)H-thymidine incorporation), cell proliferation (cell counts), and protein synthesis ((3)H-leucine incorporation). Antagonism of A(2) (KF17837) or A(1)/A(2) (low concentration of 1, 3-dipropyl-8-p-sulfophenylxanthine), but not A(1) (8-cyclopentyl-1, 3-dipropylxanthine), adenosine receptors blocked the growth-inhibitory effects of exogenous cAMP, but not the growth inhibitory effects of 8-bromo-cAMP (stable cAMP analogue). The growth-inhibitory effects of exogenous cAMP were enhanced by the combined inhibition of adenosine deaminase [erythro-9-(2-hydroxy-3-nonyl) adenine] and adenosine kinase (iodotubercidin). In conclusion, the extracellular cAMP-adenosine pathway exists in cardiac fibroblasts and attenuates cell growth. Pharmacological augmentation of this pathway could abate pathological cardiac remodeling in heart disease.

1-Methyl-3-isobutylxanthine↗

PubMed2000

Diuretic response to adenosine A(1) receptor blockade in normotensive and spontaneously hypertensive rats: role of pertussis toxin-sensitive G-proteins.

Adenosine A(1) receptor antagonists are being developed for use as diuretics in the treatment of hypertension, however, there is relatively little data in hypertensive animal models regarding the efficacy of these compounds. In addition, some controversy exists surrounding the role of pertussis toxin (PT)-sensitive G-proteins in the signaling pathway for receptors acted on by A(1) antagonists. Our objectives for this study were 1) to compare the diuretic, natriuretic, and cardiovascular effects of acute A(1) receptor blockade in spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto rats (WKY); and 2) to determine whether the diuretic effects are mediated through a PT-sensitive mechanism. Acute administration of the selective A(1) antagonist 1, 3-dipropyl-8-cyclopentylxanthine (DPCPX; 10 microgram/kg/min) increased urine output (410 +/- 116 and 317 +/- 86 microliter/30 min/g kidney) and sodium excretion (90.3 +/- 25.6 and 76.8 +/- 18.2 micromol/30 min/g kidney) similarly in WKY and SHR, respectively. DPCPX significantly decreased mean arterial blood pressure in SHR (-11.4 +/- 2.7 mm Hg), but not WKY. Prior treatment with PT (30 microgram/kg i.v.) abolished the diuretic response to DPCPX in both SHR and WKY. In a subsequent experiment in PT-treated Sprague-Dawley rats, DPCPX failed to evoke a diuretic response, whereas coinfusion of furosemide with DPCPX induced marked diuresis. Our results indicate that acute DPCPX administration produces similar natriuretic/diuretic effects in SHR and WKY, with beneficial effects on blood pressure in SHR. PT abolishes the response to DPCPX, indicating that the natriuretic/diuretic response to DPCPX is mediated via blockade of A(1) receptors linked to tubular sodium transport through PT-sensitive G-proteins.

Animals↗

PubMed2000

Preglomerular microcirculation expresses the cAMP-adenosine pathway.

UNLABELLED: The purpose of this study was to investigate whether the extracellular cAMP-adenosine pathway (i.e., transport of cAMP out of cells followed by extracellular conversion of cAMP to adenosine) exists in preglomerular microvessels (PGMVs). Incubation of PGMVs for 1 h with 30 microM cAMP increased the amount of extracellular adenosine from 163 +/- 18.6 (n = 18) to 9810 +/- 604 (n = 12) pmol/mg of protein (P < 10(-6)). The phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX; 1 mM; n = 6) and the ecto-phosphodiesterase inhibitor 1, 3-dipropyl-8-p-sulfophenylxanthine (DPSPX; 1 mM; n = 6) significantly (P < 10(-6) and P < 10(-5), respectively) reduced the cAMP-induced increase in extracellular adenosine. Incubation of PGMVs for 1 h with isoproterenol (beta-adrenoceptor agonist; 1 microM) + IBMX (0.1 mM) increased the amount of extracellular cAMP from 0.800 +/- 0.047 to 22.3 +/- 2.20 pmol/mg of protein (P < 10(-6); n = 41). In PGMVs incubated with isoproterenol (1 microM) + IBMX (0.1 mM) for 1 h, there was a significant (P < 10(-4)) linear (r(2) = 0.6) relationship between intracellular and extracellular cAMP levels. Incubation of PGMVs for 1 h with 1 microM isoproterenol increased the amount of extracellular adenosine from 163 +/- 18.6 (n = 18) to 297 +/- 38.3 (n = 12) pmol/mg of protein (P =.002). Propranolol (beta-adrenoceptor antagonist; 1 microM; n = 7), IBMX (1 mM; n = 14), and DPSPX (1 mM; n = 12) blocked (P =.037, P =.015, and P =.026, respectively) isoproterenol-induced increases in extracellular adenosine. CONCLUSIONS: PGMVs transport endogenous cAMP to the extracellular compartment and metabolize extracellular cAMP to adenosine. This pathway can increase extracellular levels of adenosine during beta-adrenoceptor activation of adenylyl cyclase.

1-Methyl-3-isobutylxanthine↗

PubMed2000

[Detection of Mycoplasma genitalium in throat by nested polymerase chain reaction and analysis of DNA sequencing in pediatric patients with acute upper respiratory tract infections].

OBJECTIVE: To explore the relation between Mycoplasma genitalium (Mg) and acute upper respiratory tract infection in pediatric patients by using nested polymerase chain reaction(nPCR) and analysis of DNA sequencing techniques. METHODS: The specimens of throat swab were obtained in 62 acute upper respiratory tract infections children and 80 health children. The two kinds of Mg species-specific, in which the sequences of I-III and V-VII variable regions of Mg 16Sr RNA gene were detected by using nPCR technique. DNA sequences of positive product were detected and analysed. RESULTS: The Positive rate of health children is 5% (4/80), while the acute upper respiratory tract infection children is 21% (13/62). The difference is significant (P < 0.001). The DNA sequences of positive product shows that: there are two point mutation(T-->C) in the sequences of V-VII variable regions of throat swab of one pediatric patient, other sequences are same as those Mg type strain(G-37T). CONCLUSIONS: Acute upper respiratory tract infection of pediatric patients have relation with Mg. There are Mg mutant strain in China.

Adhesins, Bacterial↗

PubMed2000

High frequency loss of heterozygosity in the region of the DBH locus in bladder cancer.

OBJECTIVE: To determine the location of a putative tumor suppressor gene (TSG), and evaluate the frequency loss of heterozygosity (LOH) of the long arm of chromosome 9 (9q) in bladder cancer. METHODS: We analyzed 25 patients with bladder cancer for LOH of 9q using 25 high-density microsatellite markers. RESULTS: Twenty-three samples (92%) showed LOH at least at one locus on 9q. We identified that the commonly deleted region were at 9q12-q21, 9q22, and 9q34. The rate of LOH was 44.0%, 22.7%, 22.7%, 16.0%, 12.0% on DBH, D9S15, D9S1815, D9S1831, D9S176 locus, respectively, and was not significantly related with grades and stages of tumor. CONCLUSION: These data suggest that alteration of a TSG at DBH of 9q may play an important role in the development of bladder cancer.

Chromosomes, Human, Pair 9↗

PubMed1999

Controlled Formation of Low-Volume Liquid Pillars between Plates with a Lattice of Wetting Patches by Use of a Second Immiscible Fluid.

We describe a method for forming an array of microdroplets between two plates, at least one of which is patterned with a lattice of wetting patches, using a second immiscible fluid to control droplet formation. The method may be useful for performing multiple, small-volume biochemical reactions in parallel. We analyze the forces responsible for droplet formation, describe results of a computer simulation using Surface Evolver, and derive an analytic criterion for droplet formation in terms of the contact angles of the droplet:second fluid interface on the wetting patches and surrounding surface, the diameter of the wetting patches, the distance between wetting patches, and the distance between the plates. Copyright 1999 Academic Press.

Journal Article↗

PubMed1999

Direct adenoviral gene transfer of viral IL-10 to rabbit knees with experimental arthritis ameliorates disease in both injected and contralateral control knees.

IL-10, a cytokine produced primarily by macrophages, B lymphocytes, and Th2 cells, has both immunostimulatory and immunosuppressive properties. A homologue of IL-10 encoded by EBV, known as viral IL-10 (vIL-10), is also able to suppress the immune response, but may lack some of the immunostimulatory properties of IL-10. To evaluate the potential of vIL-10 to block the progression of rheumatoid arthritis, we have utilized a replication-defective adenovirus vector to deliver the gene encoding vIL-10 to the knee joints of rabbits with Ag-induced arthritis. Intraarticular expression of vIL-10 significantly reduced leukocytosis, cartilage matrix degradation, and levels of endogenous rabbit TNF-alpha, as well as the degree of synovitis, while maintaining high levels of cartilage matrix synthesis. Interestingly, an antiarthritic effect was also observed in opposing contralateral control knee joints that received only a marker gene. An adenoviral vector carrying the enhanced green fluorescent protein marker gene was used to demonstrate that a morphologically similar subset of cells infected in the injected knee joint are able to traffic to the uninjected contralateral knee joint. Our results suggest that direct, local intraarticular delivery of the vIL-10 gene may have polyarticular therapeutic effects.

Adenoviruses, Human↗

PubMed1999

Lessons learned from gene transfer approaches.

Recent technological advances allow the transfer of genes to the synovial lining of joints. As well as opening novel opportunities for therapy, these techniques provide valuable new tools for the study of synovitis and other aspects of the biology of joints in health and disease. This article reviews briefly the results of experiments in which selected genes have been transferred to the knee joints of healthy rabbits and rabbits with antigen-induced arthritis.

Animals↗

PubMed1999

[Study of NAIP gene in spinal muscular atrophy]

OBJECTIVE: Investigating the correlation between the genotype and spinal muscular atrophy(SMA) clinical phenotype. METHODS: Neuronal apoptosis inhibitory protein(NAIP) gene analysis was performed by PCR amplification of exon 5 in 13 unrelated SMA patients with deletions of SMN gene. RESULTS: Two Type-I patients(2/5, 40%) lacked the NAIP exon 5. CONCLUSION: The results suggest a possible correlation between NAIP gene deletion and the disease severity of SMA.

Journal Article↗

PubMed1999

[Mutations of the fibroblast growth factor receptor 3 gene in achondroplasia].

OBJECTIVE: To evaluate whether mutation in the exon 10 of the fibroblast growth factor receptor 3(FGFR3) gene in common in Chinese patients with achondroplasia. METHODS: Genomic DNA from seven sporadic cases of achondroplasia was studied by using PCR-SSCP and restriction enzymes. RESULTS: All patients carried the same glycine-to-arginine mutation at codon 380(G380R) of the transmembrane domain of FGFR3. CONCLUSION: The results suggest that the G380R mutation of FGFR3 is also a frequent mutation causing achondroplasia in Chinese. Detecting FGFR 3 gene mutation with PCR-SSCP and restriction enzymes analysis is a convenient, rapid and reliable molecular diagnostic assay for prenatal and early diagnosis of achondroplasia.

Achondroplasia↗

PubMed1999

Infection of intact human islets by a lentiviral vector.

The transfer of genes encoding immunomodulatory proteins to islets can be used to improve islet function, block apoptosis, and inhibit rejection following transplantation. Adenoviral vectors have been shown to infect intact human islets, but the immunogenicity and transient gene expression of the current adenoviral vectors may hinder their use clinically for islet transplantation. In this report, we compared an HIV-1-based lentiviral vector with the E1-deleted adenoviral vehicle of the Ad5 type for gene transfer to human islets in vitro. We demonstrate that at similar viral particle concentrations per islet that an HIV-based lentiviral vector is able to infect beta-cells within an intact human islet at an efficiency similar to an adenoviral vector. In addition, both the adenoviral and lentiviral vectors were able to express significant levels of soluble interleukin-1 receptor antagonist (IL-1Ra) protein following infection of intact islets. More importantly, there was no impairment of islet beta-cell function following adenoviral and lentiviral infection in responding to glucose stimulation. These results support the utility of replication-defective lentiviral vectors as efficient gene delivery vehicles to islets to faciliate transplantation of islets for therapy of type I diabetes.

Adenoviridae↗

PubMed1999

Intra-articular delivery of a herpes simplex virus IL-1Ra gene vector reduces inflammation in a rabbit model of arthritis.

To evaluate the use of HSV-based vectors for arthritis gene therapy we have constructed a first-generation, ICP4 deficient, replication defective herpes simplex virus (HSV) vector (S/0-) and a second-generation HSV vector derivative (T/0-) deficient for the immediate-early genes ICP4, 22 and 27, each carrying a soluble TNF receptor or IL-1 receptor antagonist transgene cassette. A rabbit synovial-fibroblast line in culture, infected by either vector enabled high-level expression of the transgene product. However, following a single intra-articular injection of the vectors into rabbit knee joints, only the second-generation, HSV T/0- vector expressed detectable levels of soluble TNFR in synovial fluid. Synovial lavage fluid from inoculated joints con- tained up to 12 ng/ml of soluble receptor that persisted at detectable, but reduced levels for at least 7 days. When tested in an experimental model of arthritis generated by intra-articular overexpression of interleukin-1beta using retrovirus transduced synovial cells, the HSV T/0- vector expressing the interleukin-1 receptor antagonist was found to inhibit leukocytosis and synovitis significantly. The improved levels and duration of intra-articular transgene expression achieved via HSV-mediated gene delivery suggest that an HSV vector system could be used for therapeutic applications in patients with rheumatoid arthritis (RA) and other joint-related inflammatory diseases.

Adoptive Transfer↗

PubMed1999

Angiotensin receptor subtype 1 mediates angiotensin II enhancement of isoproterenol-induced cyclic AMP production in preglomerular microvascular smooth muscle cells.

In a previous study, we found that angiotensin (Ang) II enhances beta-adrenoceptor-induced cAMP production in cultured preglomerular microvascular smooth muscle cells (PMVSMCs) obtained from spontaneously hypertensive rats. The purpose of the present investigation was to identify the Ang receptor subtypes that mediate this effect. In our first study, we compared the ability of Ang II, Ang III, Ang (3-8), and Ang (1-7) to increase cAMP production in isoproterenol (1 microM)-treated PMVSMCs. Each peptide was tested at 0.1, 1, 10, 100, and 1000 nM. Both Ang II and Ang III increased intracellular (EC50s, 1 and 11 nM, respectively) and extracellular (EC50s, 2 and 14 nM, respectively) cAMP levels in a concentration-dependent fashion. In contrast, Ang (3-8) and Ang (1-7) did not enhance either intracellular or extracellular cAMP levels at any concentration tested. In our second study, we examined the ability of L 158809 [a selective Ang receptor subtype 1 (AT1) receptor antagonist] to inhibit Ang II (100 nM) and Ang III (100 nM) enhancement of isoproterenol (1 microM)-induced cAMP production in PMVSMCs. L 158809 (10 nM) abolished or nearly abolished (p <.001) Ang II and Ang III enhancement of isoproterenol-induced intracellular and extracellular cAMP levels. In contrast, PD 123319 (300 nM; a selective AT2 receptor antagonist) did not significantly alter Ang II enhancement of isoproterenol-induced intracellular or extracellular cAMP levels. We conclude that AT1 receptors, but not AT2, Ang (3-8), nor Ang (1-7) receptors mediate Ang II and Ang III enhancement of beta-adrenoceptor-induced cAMP production in cultured PMVSMCs.

Angiotensin II↗

PubMed1999

[Study of NAIP gene in spinal muscular atrophy].

OBJECTIVE: Investigating the correlation between the genotype and spinal muscular atrophy(SMA) clinical phenotype. METHODS: Neuronal apoptosis inhibitory protein(NAIP) gene analysis was performed by PCR amplification of exon 5 in 13 unrelated SMA patients with deletions of SMN gene. RESULTS: Two Type-I patients(2 M5, 40%) lacked the NAIP exon 5. CONCLUSION: The results suggest a possible correlation between NAIP gene deletion and the disease severity of SMA.

Child↗