Biomedical subjects

S P Ho

Publications and source records attributed to S P Ho.

At least 19 recordsLinked to original sources

PubMed2006

Disturbance of systemic antioxidant profile in nonsmall cell lung carcinoma.

The present study aimed to determine the alterations of antioxidant activities in erythrocytes from patients with nonsmall cell lung carcinoma (NSCLC). A comparative study of the systemic antioxidant activities in red blood cell lysate from subjects with NSCLC and healthy control subjects was conducted. The antioxidants catalase, superoxide dismutase (SOD) and glutathione peroxidase (GPx) were measured using chemical kinetic reactions under spectrophotometry. In total, 189 cases of mostly advanced-stage IIIB or stage IV NSCLC and 202 healthy controls were studied. In subjects with lung cancer, there was similar catalase activity, lower SOD activity (median (interquartile range) 13.4 (9.0-27.2) versus 48.7 (27.0-64.3) U x (ghaemoglobulin(Hb)(-1)), and higher GPx activity (175.2 (126.6-288.3) versus 49.2 (39.5-59.2) mU x (gHb)(-1)) compared with controls. The antioxidant activities in lung cancer subjects were not associated with age, sex, smoking status, or tumour cell types. However, more advanced disease (stage IV compared with stage IIIB) was associated with lower SOD activity. Using multivariable analysis, the presence of lung cancer independently predicted SOD and GPx activities. In conclusion, nonsmall cell lung carcinoma in Chinese subjects is associated with alterations in systemic antioxidant activities, which may play an important role in carcinogenesis.

Adult↗

PubMed2006

Polymorphisms in manganese superoxide dismutase and catalase genes: functional study in Hong Kong Chinese asthma patients.

BACKGROUND: Reactive oxygen species may contribute to the pathogenesis of asthma. Functional genetic polymorphisms of antioxidant enzymes, superoxide dismutase (SOD) and catalase are good candidates for asthma susceptibility. OBJECTIVE: To investigate the association of the manganese-containing form of SOD (MnSOD) gene at amino acid position 16 (Val16Ala) and catalase gene in the promoter at A-21T and C-262T polymorphisms and asthma in a Hong Kong Chinese population. METHODS: The association study was conducted in a case-control design in asthma patients (n=251) and healthy controls (n=316) by genotyping. The functional significance was assessed by determining erythrocyte SOD and catalase activity. RESULTS: The Val allele of MnSOD at Val16Ala and the A allele of catalase gene at A-21T were not different between patients and controls, while the C allele of catalase gene at C-262T was found to be significantly different between patients and controls (P=0.033). The less frequent variant of catalase gene (-262T) was found to be protective from the development of asthma in a Hong Kong Chinese non-smoking population (adjusted odds ratio=0.35, 0.15-0.85; P=0.017). Asthma patients had elevated erythrocyte SOD and catalase activities in comparison with healthy controls (P<0.01). However, their activities were not associated with different genotypes within healthy controls or asthma patients. CONCLUSION: This is the first report showing that SOD and catalase functional activities are not associated with their respective genetic polymorphisms but related to the presence of asthma in a Hong Kong Chinese population.

Alleles↗

PubMed2004

Ultrastructure and nanomechanical properties of cementum dentin junction.

The attachment between cementum and dentin has been given several definitions and nomenclature, including: interzonal layer, intermediate cementum, collagen hiatus, Hopewell-Smith's hyaline layer, and more commonly, cementum-dentin junction (CDJ). Understanding the attachment of two structurally dissimilar hard tissues such as cementum and dentin defined by a junction may provide information necessary to engineer functionally graded materials that can be used for efficient tooth restorations in clinical dentistry and other bioengineering applications. Hence, in this study, as a first step toward understanding the CDJ using a biomechanical approach, it was hypothesized that the CDJ between cementum and dentin is a wide zone with mechanical properties significantly lower than the neighboring tissues. The structure of the CDJ was studied using an atomic force microscope (AFM), and site-specific mechanical response of the three regions; cementum, CDJ, and dentin were determined using an AFM-nanoindenter under dry and wet conditions. The AFM results of the CDJ demonstrated a valley under dry conditions and a peak under wet conditions. The magnitude of the depth of the valley was approximately the same as the height of the peak of the CDJ, ranging from 10 to 40 microm. The nanomechanical properties under dry conditions indicated no significant difference (p > 0.05) in elastic modulus and hardness of the CDJ (Er = 17.5 +/- 2.7 GPa, H = 0.6 +/- 0.1 GPa) and cementum (Er = 18.7 +/- 2.5 GPa, H = 0.6 +/- 0.1 GPa). The mechanical properties of the CDJ were significantly lower (p << 0.05) than dentin (Er = 19.9 +/- 2.9 GPa, H = 0.6 +/- 0.1 GPa) under dry conditions. However, under more relevant hydrated conditions, the mechanical properties of CDJ (Er 3.0 +/- 0.7 GPa, H = 0.1 +/- 0.0 GPa) were significantly lower (p << 0.05) than those of cementum (Er 6.8 +/- 1.9 GPa, H = 0.2 +/- 0.1 GPa) and dentin (Er 9.4 +/- 2.3 GPa, H = 0.3 +/- 0.1 GPa). Based on the results from this study, it can be concluded that the CDJ can be regarded as a wide zone containing large quantities of proteins including collagen that contribute to hydration and significantly reduce mechanical properties, compared with the adjacent hard tissues, cementum, and dentin. The lower mechanical properties of the CDJ may make it possible for it to redistribute occlusal loads to the alveolar bone.

Aged↗

PubMed2003

Nanoindentation properties of compression-moulded ultra-high molecular weight polyethylene.

This paper investigates the elastic modulus and hardness of untreated and treated compression-moulded ultra-high molecular weight polyethylene (UHMWPE) tibial inserts of a total knee replacement (TKR) prosthesis. Investigations were carried out at a nanoscale using a Nanoindenter at penetration depths of 100,250 and 500 nm. The nanomechanical properties of surface and subsurface layers of the compression-moulded tibial inserts were studied using the untreated UHMWPE. The nanomechanical properties of intermediate and core layers of the compression-moulded tibial insert were studied using the cryoultrasectioned and etched UHMWPE treated samples. The cryoultrasectioning temperature (-150 degrees C) of the samples was below the glass transition temperature, Tg (-122 +/- 2 degrees C ), of UHMWPE. The measurement of the mechanical response of crystalline regions within the nanostructure of UHMWPE was accomplished by removing the amorphous regions using a time-varying permanganic-etching technique. The percentage crystallinity of UHMWPE was measured using differential scanning calorimetry (DSC) and the Tg of UHMWPE was determined by dynamic mechanical analysis (DMA). Atomic force microscopy (AFM) was used to assess the effect of surface preparation on the samples average surface roughness, Ra. In this study, it was demonstrated that the untreated UHMWPE samples had a significantly lower (p < 0.0001) elastic modulus and hardness relative to treated UHMWPE cryoultrasectioned and etched samples at all penetration depths. No significant difference (p > 0.05) in elastic modulus and hardness between the cryoultrasectioned and etched samples was observed. These results suggest that the surface nanomechanical response of an UHMWPE insert in a total joint replacement (TJR) prosthesis is significantly lower compared with the bulk of the material. Additionally, it was concluded that the nanomechanical response of material with higher percentage crystallinity (67 per cent) was predominantly determined by the crystalline regions within the semi-crystalline UHMWPE nanostructure.

Biocompatible Materials↗

PubMed2002

Effects of the sample preparation temperature on the nanostructure of compression moulded ultrahigh molecular weight polyethylene.

In this study, the effects of the sample sectioning temperature on the surface nanostructure and mechanical response of compression moulded ultrahigh molecular weight polyethylene (UHMWPE) at a nanometer scale (nanomechanical properties) have been characterized. The primary focus of this work was to determine if the sample sectioning temperature significantly changed the nanostructure of UHMWPE, while the secondary focus was to characterize the effect on the mechanical response due to the changes in the sectioned surface nanostructure. The goals of this study were: (a) to investigate the potential possibility of creating surface artefacts by the sample preparation technique by sectioning at different temperatures relative to the published range of glass transition temperatures, Tg, for PE (-12, -80 and -25 degrees C); (b) to determine the possibility of molecular orientation induced by plastic deformation of the UHMWPE sample during the process of sample preparation; (c) to measure the relative difference in nanomechanical properties owing to evolution of different nanostructures as a function of sample sectioning temperature. Field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and nanoindentation were used to demonstrate that the sectioning temperature caused a change in nanostructure of the compression moulded UHMWPE sectioned surface, explaining the change in mechanical response to indentation at a nanoscale. In this study, it was demonstrated that significant plastic deformation occurs when a shear stress is applied between the glass or diamond blade and the UHMWPE during sample preparation under ambient conditions at a temperature of 22 degrees C. These results also suggest that an optimum sample sectioning temperature should definitely be below the measured Tg of the polymer.

Artifacts↗

PubMed2002

A case of uterine artery pseudoaneurysms.

Uterine artery pseudoaneurysms is a rare cause of haemorrhage but is potentially life-threatening and can occur after common gynaecological operations such as a Caesarean section or a hysterectomy. A 33-year-old woman who developed secondary postpartum haemorrhage after a Caesarean section was diagnosed to have uterine artery pseudoaneurysms on ultrasound scan. She was treated with bilateral uterine artery embolisation via selective catherisation of uterine arteries. Good outcome with the aneurysms remaining obliterated was obtained. Angiographic embolisation is a safe and effective method of treating postpartum haemorrhage in haemodynamically stable patients and should be an option before resorting to surgery in appropriately selected cases.

Adult↗

PubMed2002

Malignant mixed Mullerian tumours of the uterus--a ten-year experience.

OBJECTIVES: To review the clinico-pathological features of malignant mixed Mullerian tumours of the uterine corpus, their prognosis and treatment outcome. METHODS: A retrospective study of malignant mixed Mullerian tumours of the uterus seen at KK Women's & Children's Hospital from January 1989 to December 1998. RESULTS AND CONCLUSION: Twenty-six patients with mean age of 56.5 years were analysed. Twenty (76.9%) were menopausal. None had previous pelvic irradiation. Vaginal bleeding and uterine enlargement were the commonest presenting symptom and sign. Diagnostic dilatation and curettage obtained the diagnosis in 15 patients. Majority of patients had surgery with adjuvant chemotherapy, while adjuvant radiotherapy was offered only recently. Positive peritoneal washings were significantly associated with advanced disease. There were seven patients with stage I, four with stage II, nine with stage III and four with stage IV disease. There were 17 homologous and nine heterologous tumours. Presence of heterologous stromal components did not influence the stage of the disease. Increasing depth of myometrial invasion was associated with poorer survival. Prognosis of patients with stage III and IV disease were poor, with none surviving to two years. All the patients with stage I disease were still alive at the end of the study period. In conclusion, malignant mixed Mullerian tumours of the uterine corpus are aggressive tumours associated with poor prognosis.

Adolescent↗

PubMed2001

Antagonism of CRF(2) receptors produces anxiolytic behavior in animal models of anxiety.

Two pharmacologically distinct CRF receptors are distributed in different brain regions and peripheral tissues. Studies suggest that CRF(1) receptors play an important role in mediating the anxiety provoking effects of CRF. In contrast, far less functional information is available on CRF(2) receptors. Therefore, we conducted dose response studies using antisauvagine-30 (anti-SVG-30, 0-20 microg, 20-min pretreatment, i.c.v.), a potent CRF(2) peptide antagonist, and tested rats in three models of anxiety - the conditioned freezing, the elevated plus maze, and the defensive-withdrawal test. Anti-SVG-30 produced a significant dose-dependent reduction in conditioned freezing. In the elevated plus maze test, administration of anti-SVG-30 effectively increased the number of entries and time spent in the open arms. In the defensive-withdrawal test, anti-SVG-30 treatment facilitated exploratory activity in a large illuminated open field. Thus, in all three animal models, administration of anti-SVG-30 was consistent in producing an anxiolytic-like behavioral effect. In addition, a dose of anti-SVG-30 (10 microg) that produced anxiolytic-like behavior had no significant effects on locomotor activity measured in an automated activity box. This latter finding suggests that antagonism of CRF(2) receptors is not associated with a non-specific increase in behavioral movements. These results provide evidence that, in addition to CRF(1) receptors, CRF(2) receptors may play an important role in the mediation of anxiety behavior.

Animals↗

PubMed2001

Attenuation of fear conditioning by antisense inhibition of brain corticotropin releasing factor-2 receptor.

Corticotropin releasing factor (CRF) is an important regulator of the endocrine, behavioral, autonomic and immune responses to stress. Two high affinity CRF receptors have been identified, which are distributed in distinct anatomical regions. CRF(1) receptors have been relatively well characterized and antagonists to this receptor effectively block stress-induced behaviors in rodents. The function of CRF(2) receptors, which are highly expressed in limbic brain regions, is less well understood. Therefore, an antisense oligonucleotide approach was used to study the role of CRF(2) receptors in the lateral septum in rats. An antisense oligonucleotide directed against the CRF(2) receptor mRNA reduced expression of CRF(2) receptors by 60--80%. In shock-induced freezing tests, animals administered the antisense oligonucleotide exhibited a significant reduction in freezing duration. However, pain sensitivity and locomotor activity were unaltered. A four-base mismatch of the antisense sequence had no significant effects on CRF(2) receptor density and on freezing behavior. These data support the involvement of CRF(2) receptors in fear conditioning. CRF(1) receptor antagonists also reduce freezing in this test. Additional studies to determine the effects of simultaneous inhibition of both receptor subtypes show that rats receiving both CRF(2) receptor antisense oligonucleotide and CRF(1) receptor antagonist froze significantly less than animals treated with either agent alone. These results provide additional evidence for the role of CRF(2) receptors in mediating the stress-induced actions of endogenous CRF.

Animals↗

PubMed2000

Aspartyl beta -hydroxylase (Asph) and an evolutionarily conserved isoform of Asph missing the catalytic domain share exons with junctin.

The mouse aspartyl beta-hydroxylase gene (Asph, BAH) has been cloned and characterized. The mouse BAH gene spans 200 kilobase pairs of genomic DNA and contains 24 exons. Of three major BAH-related transcripts, the two largest (6,629 and 4,419 base pairs) encode full-length protein and differ only in the use of alternative polyadenylation signals. The smallest BAH-related transcript (2,789 base pairs) uses an alternative 3' terminal exon, resulting in a protein lacking a catalytic domain. Evolutionary conservation of this noncatalytic isoform of BAH (humbug) is demonstrated in mouse, man, and Drosophila. Monoclonal antibody reagents were generated, epitope-mapped, and used to definitively correlate RNA bands on Northern blots with protein species on Western blots. The gene for mouse junctin, a calsequestrin-binding protein, was cloned and characterized and shown to be encoded from the same locus. When expressed in heart tissue, BAH/humbug preferably use the first exon and often the fourth exon of junctin while preserving the reading frame. Thus, three individual genes share common exons and open reading frames and use separate promoters to achieve differential expression, splicing, and function in a variety of tissues. This unusual form of exon sharing suggests that the functions of junctin, BAH, and humbug may be linked.

Amino Acid Sequence↗

PubMed2000

RNA mapping: selection of potent oligonucleotide sequences for antisense experiments.

The importance of finding good antisense sequences cannot be underestimated. Poor inhibition of the targeted protein can compromise the final outcome of an antisense experiment, making it difficult to arrive at a definitive understanding of the function of the protein of interest. In antisense therapeutics, identification of potent sequences becomes even more important. RNA mapping greatly increases the odds of finding active sequences. When antisense sequences are selected randomly or by gene walking, a substantial number of the oligonucleotides have little to no activity. In contrast, oligonucleotides selected by RNA mapping typically produce an antisense inhibition of greater than 50%. Oligonucleotides targeted to 60% of the accessible sites in the 5' portion of the multidrug resistance transcript inhibited P-glycoprotein function with high potency. In the angiotensin type 1 receptor system, oligonucleotides to the eight accessible sites examined inhibited AT1 receptor binding by at least 50%, with oligonucleotides to four of the sites producing at least 70% inhibition. The RNA mapping assay, which is based on standard molecular techniques, therefore provides an easy and reliable method for potent antisense sequence selection.

Base Sequence↗

PubMed2000

Diastolic blood pressure is related to urinary sodium excretion in hypertensive Chinese patients.

We studied 70 Hong Kong Chinese patients with untreated hypertension and 47 normotensive controls. Blood pressure measurements and 24-h urine collection were performed for each patient, and were repeated 12 weeks later in 14 hypertensive patients who remained untreated. Twenty-two hypertensive patients underwent ambulatory blood pressure monitoring. The primary hypothesis tested was a correlation between diastolic blood pressure and 24-h urinary sodium excretion. In the hypertensive patients, diastolic blood pressure correlated with 24-h urinary sodium excretion (r=0.41, p<0.001), even after adjustment for age, gender, body mass index, ethanol intake and season (r=0.34, p=0.02). In normotensive controls, diastolic blood pressure did not correlate with sodium excretion (r=0.21, p=0.16). A correlation between diastolic blood pressure and sodium excretion was also observed in the patients who underwent ambulatory blood pressure monitoring (r=0.47, p=0.026), and in repeat measurements in untreated patients (r=0.60, p=0.02). Systolic blood pressure did not correlate with sodium excretion, although it increased with patient age (0.6+/-0.1 mmHg/year, p<0.001). In a multiple regression analysis with diastolic blood pressure as the dependent variable, the regression coefficient was 0.06+/-0.02 mmHg/mmol Na. The regression coefficients for ambulatory diastolic blood pressure and diastolic pressure repeated at 12 weeks were 0.07+/-0.03 and 0. 09+/-0.04 mmHg/mmol Na, respectively. Urinary sodium excretion was related to diastolic blood pressure in our hypertensive patients, accounting for 17% of the variance of diastolic blood pressure.

Adolescent↗

PubMed2000

Antibacterial effect of chloramphenicol, thiamphenicol and florfenicol against aquatic animal bacteria.

The minimum inhibitory concentration (MIC) was measured to evaluate the antibacterial activities of chloramphenicol (CP), thiamphenicol (TP) and florfenicol (FFC) against the aquatic bacterial isolates from soft-shell turtles, fish and shellfish. Amoxicillin (AMPC), oxytetracycline (OTC) and oxolinic acid (OA) were included to compare with above protein synthesis inhibitors. The results showed that the order of MIC range of the isolates from soft-shell turtles for tested drugs was OA>FFC, CP>TP> AMPC, OTC. The percentage of the resistant strains indicated that OA was the lowest (7.14%) and OTC was the highest (85.07%). The order of antibacterial activity against the isolates from fish was OA>FFC>CP>AMPC>OTC>TP. The percentage of the resistant strains revealed that OA (13.64%) and OTC (80.91%) were the lowest and the highest, respectively. For the isolates from shellfish, the order of antimicrobial activity was OA>CP, FFC>AMPC, OTC, TP. TP showed the greatest percentage of the resistant strains (58.7%), but that of OA was the lowest (4.35%). The most common resistant patterns of the isolates from turtles, fish and shellfish were AMPC-OTC, CP-TP-AMPC-OTC, and FFC-CP-TP-AMPC-OTC, respectively. There were partially-complete resistance of the resistant isolates among CP, TP and FFC. The findings indicated that previous treatment might affect the choice of drug to use for aquatic bacterial diseases.

Amoxicillin↗

PubMed1999

Regulation of the angiotensin type-1 receptor by antisense oligonucleotides occurs through an RNase H-type mechanism.

Multiple, diverse sites in the coding region of the angiotensin type-1 receptor mRNA were targeted with 2'-deoxyribonucleotide antisense oligonucleotides (ONs). The uptake of 1 microM concentration of these ONs into Chinese hamster ovary cells was facilitated by the use of cationic liposomes. The antisense sequences reduced binding of 125I-angiotensin II by 57-73%, while mismatch ONs and reverse sequence ONs produced little reduction in receptor binding. These reductions in AT1 receptor binding were accompanied by comparable decreases in AT1 receptor mRNA levels. Furthermore, mRNA cleavage fragments corresponding in size to 3'-cleavage fragments were observed with two of the antisense ONs, consistent with the involvement of an RNase H-type enzyme. When 2'-methoxyribonucleotide analogs of these same sequences were tested, AT1 receptor mRNA levels were unchanged even though small reductions in AngII binding were observed. Antisense effects seen with these 2'-methoxyribonucleotide sequences may have arisen through a translational arrest mechanism. Direct comparisons between 2'-deoxyribonucleotide analogs and their 2'-methoxyribonucleotide counterparts show that antisense effects are significantly larger when they are mediated through an RNase H-type mechanism. 2'-methoxyribonucleotide sequences were most effective when they were directed against the translation initiation codon.

Angiotensin I↗

PubMed1999

Pharmacokinetic and depletion studies of sarafloxacin after oral administration to eel (Anguilla anguilla).

The pharmacokinetics of sarafloxacin applied by oral gavage at a dose of 15 mg/kg b.w. was studied in eel (Anguilla anguilla) at water temperature of 24 degrees C. Sarafloxacin levels were determined using high performance liquid chromatography with a quantitation limit of 0.07 microg/ml or gram. The time to peak plasma concentration, Tmax, was 12 hr and peak concentration, Cmax, was 2.64 microg/ml. The absorption rate constant (k(a)) was 0.23 hr(-1) (r=0.996). The drug disposition curve after Tmax was fitted to a two-compartment open model. The distribution rate constant (alpha) was 0.085 hr(-1) (r=0.972), and the half-life (t(1,2alpha)) was 8.15 hr. The elimination rate constant (beta) was 0.023 hr(-1) (r=0.909), and the half-life (t(1/2beta)) was 30.13 hr. The estimated area under the curve, AUC, was 56.7 microg.hr/ml. The peak concentrations of drug in liver, kidney, muscle, and skin were 13.39 (12 hr), 5.53 (12 hr), 1.82 (24 hr), and 0.78 microg/g (40 hr), respectively. The time for sarafloxacin mean levels to fall below detectable limits in the plasma, muscle, and skin were 7 days but for the liver and kidney were 14 days.

Administration, Oral↗

PubMed1999

Antisense oligonucleotides for target validation in the CNS.

Although antisense oligonucleotides have been used in cell-based antisense experiments for nearly two decades, studies to investigate the function of CNS proteins in living animals were not successfully conducted until recently. Oligonucleotides are not transported across the blood-brain barrier to any appreciable extent. Consequently, these molecules need to be administered directly into the brain. Antisense approaches may be especially suited to investigation of CNS proteins. Due to their specificity, antisense sequences can more easily and selectively distinguish between closely related proteins, such as receptor subtypes, in contrast to the more traditional pharmacological agents such as small molecule ligands. This review discusses some unique technical aspects surrounding oligonucleotide delivery to the brain, and summarizes some of the more noteworthy applications of antisense tools to the study of CNS protein function during the past two years.

Analgesia↗

PubMed1998

Intrastriatal and intraventricular injections of oligodeoxynucleotides in the rat brain: tissue penetration, intracellular distribution and c-fos antisense effects.

We have determined the time course, the spatial spread in brain tissue, and the intracellular distribution of biotin- and fluorescein-labeled phosphorothioate oligodeoxynucleotides (ODNs) following single injections into the rat striatum or the lateral ventricle. These time and space parameters were correlated with the ability of c-fos phosphorothioate antisense ODNs to suppress the induction of Fos protein by cocaine. A rapid and dose-dependent tissue penetration of labeled ODNs was observed following either intrastriatal or intraventricular injections of a constant sample volume. Inspection of tissue sections by confocal microscopy uncovered a distinct change in the intracellular disposition of labeled ODNs during the 24 h post-injection period. At 1, 6 and 12 h, the vast majority of the fluorescent signal was confined to the interstitial spaces throughout the zone penetrated by ODNs. Neuronal nuclei displayed faint labeling along the outer portion of the nucleus at 1 and 6 h post-injection. At these time-points, ODNs were not detected in the cytoplasm. By 16 h, ODNs were barely detectable in the extracellular space and absent from neuronal nuclei. Instead, ODNs were seen in large cytoplasmic granules of neurons throughout the tissue zone penetrated by the ODNs. Experiments with intrastriatal injections of antisense ODNs to c-fos mRNA revealed Fos suppression between 3 and 12 h, but not at 16 and 24 h. This combined analysis has revealed that (1) restricted tissue penetration by ODNs limits their antisense effects on protein expression, and (2) depletion of extracellular ODNs and sequestration of c-fos antisense ODNs into large intracellular granules coincides with the loss of their biological activity.

Animals↗

PubMed1998

Mapping of RNA accessible sites for antisense experiments with oligonucleotide libraries.

Antisense experiments are often complicated by the lack of reliable methods for selecting effective antisense sequences. Chimeric oligodeoxynucleotide (ODN) libraries and ribonuclease H (RNase H) were used to identify regions on the 1253 nucleotide angiotensin type-1 receptor (AT1) mRNA that are accessible to hybridization with antisense ODNs. Phosphorothioate antisense ODNs targeted against accessible sites reduced AT1 receptor levels by at least 50% in cell culture. ODNs to 4 sites produced a 70% to 80% reduction. In contrast, most sequences targeted between accessible sites were ineffective. When injected into the brains of rats, ODNs targeted to accessible sites reduced AT1 (by 65%) but not AT2 receptor levels. Additionally, AT1 receptor function as measured by agonist-induced water intake, was significantly attenuated in these rats. ODNs directed between accessible sites were ineffective at suppressing water intake. RNA mapping can be applied to any RNA target to facilitate selection of multiple, active antisense sequences for cell culture and in vivo experiments.

Animals↗