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Biomedical subjects

H Sun

Publications and source records attributed to H Sun.

At least 325 records · Page 18Linked to original sources
PubMed1997

Crx, a novel Otx-like paired-homeodomain protein, binds to and transactivates photoreceptor cell-specific genes.

The otd/Otx gene family encodes paired-like homeodomain proteins that are involved in the regulation of anterior head structure and sensory organ development. Using the yeast one-hybrid screen with a bait containing the Ret 4 site from the bovine rhodopsin promoter, we have cloned a new member of the family, Crx (Cone rod homeobox). Crx encodes a 299 amino acid residue protein with a paired-like homeodomain near its N terminus. In the adult, it is expressed predominantly in photoreceptors and pinealocytes. In the developing mouse retina, it is expressed by embryonic day 12.5 (E12.5). Recombinant Crx binds in vitro not only to the Ret 4 site but also to the Ret 1 and BAT-1 sites. In transient transfection studies, Crx transactivates rhodopsin promoter-reporter constructs. Its activity is synergistic with that of Nrl. Crx also binds to and transactivates the genes for several other photoreceptor cell-specific proteins (interphotoreceptor retinoid-binding protein, beta-phosphodiesterase, and arrestin). Human Crx maps to chromosome 19q13.3, the site of a cone rod dystrophy (CORDII). These studies implicate Crx as a potentially important regulator of photoreceptor cell development and gene expression and also identify it as a candidate gene for CORDII and other retinal diseases.

Amino Acid Sequence↗
PubMed1997

Pharmacologic enhancement of atrial electrical defibrillation efficacy: role of ibutilide.

The study was designed to identify the influence of ibutilide on activation during atrial fibrillation (AF) and determine its role in enhancing the efficacy of electrical conversion of AF. Vagally-mediated acute AF was induced in 12 anesthetized dogs. In 5 dogs, a cross-shaped epicardial patch containing 16 recording electrodes was placed on the right atrium. In 7 dogs, defibrillation patch electrodes overlying both atria were used to deliver biphasic shocks (50% tilt; 90 microF). Measurements were made at baseline and following ibutilide (0.075 mg/kg bolus followed by 0.075 mg/kg infusion over 10 minutes). Right atrial multisite electrogram recordings revealed significant prolongation in AF cycle length at all sites following ibutilide. In all dogs, AF cycle length increased with ibutilide from 90 +/- 23 to 130 +/- 49 ms (p < 0.005). Whereas, atrial defibrillation threshold decreased from 0.83 +/- 0.5 to 0.53 +/- 0.29 J (p = 0.020). In conclusion, ibutilide prolongs cycle length of canine vagally-mediated acute AF. Furthermore, ibutilide facilitates electrical conversion of AF by lowering energy requirement. Thus, controlled drug infusion in conjunction with electrical defibrillation may be useful for managing AF.

Animals↗
PubMed1997

A photoreceptor cell-specific ATP-binding transporter gene (ABCR) is mutated in recessive Stargardt macular dystrophy.

Stargardt disease (STGD, also known as fundus flavimaculatus; FFM) is an autosomal recessive retinal disorder characterized by a juvenile-onset macular dystrophy, alterations of the peripheral retina, and subretinal deposition of lipofuscin-like material. A gene encoding an ATP-binding cassette (ABC) transporter was mapped to the 2-cM (centiMorgan) interval at 1p13-p21 previously shown by linkage analysis to harbour the STGD gene. This gene, ABCR, is expressed exclusively and at high levels in the retina, in rod but not cone photoreceptors, as detected by in situ hybridization. Mutational analysis of ABCR in STGD families revealed a total of 19 different mutations including homozygous mutations in two families with consanguineous parentage. These data indicate that ABCR is the causal gene of STGD/FFM.

ATP-Binding Cassette Transporters↗
PubMed1997

Gravity constraints in infant motor development.

The effect of gravity in determining if and when during infancy movements eventuate and the rate at which they develop is unknown. In accordance with intersegmental relationships (Hof, 1992), a muscle moment during infancy would have to develop more rapidly than the gravitational moment before movement could occur. In this investigation, the effect of growth through the influence of gravity on the joint moments in the axial region when infants were in a prone or supine posture was examined. A mathematical model that considers the body to be composed of transverse elliptical cylinders, 1 cm deep and of known density, was used in estimating the mass of the 16 segments of the body. The gravitational moments about 3 joints within the axial region (C7-T1, T12-L1, and the hip) were determined by summation, using the radii from the joint transverse axis to the center of mass of the segments. Infants (N = 27) aged between 9 and 36 weeks at the beginning of the study were tested monthly 6 times, and the effect of growth on the gravitational moments was represented by first-order polynomials. Age x Joint analysis of variance (ANOVA) of the mean slopes of the regressions for the gravitational moments revealed significant main effects for age and joint. The means increased monotonically with the number of segments and decreased as infants aged. The mean slopes of the neck and trunk joints were significantly smaller than that of the hip joint. With increasing age, the gravitational slope was significantly smaller. The changes in the gravitational moments during infancy are seen as likely control parameters effecting phase shifts in motor patterns during development.

Aging↗
PubMed1997

High level expression of recombinant plasminogen activator inhibitor-1 in Escherichia coli and generation of its mutants involving Asp125, Glu128 and Glu130.

Plasminogen activator inhibitor-1 (PAI-1) cDNA was expressed in Escherichia coli (E. coli) with high efficiency using a heat-inducible vector. About 100 mg of recombinant PAI-1 (rPAI-1) could be obtained from 1 liter of bacteria culture. rPAI-1 in inclusion bodies was purified by pI precipitation and Sephadex G-75 chromatography. After treatment with 4 mol/L guanidinium chloride and dialysis, the largely inactive PAI-1 gained considerably in activity as judged by its reaction with low molecular weight u-PA (LMW-u-PA). Degenerated oligonucleotides containing ApaI site and mutations at Asp125, Glu128, Glu130 in PAI-1 cDNA were synthesized. To facilitate the introduction of mutations, an ApaI site was first generated in PAI-1 cDNA using one of the oligonucleotides. Taking advantage of the APaI site, thirteen PAI-1 mutants involving Asp125, Glu128 and Glu130 were produced with these oligonucleotides using PCR. Most of the PAI-1 mutants had a similar activity as compared to wild type PAI-1, while some of the triple-site mutants had completely lost their activity.

DNA, Complementary↗
PubMed1997

Exogenous opioids influence the microcirculation of injured peripheral nerves.

Local microvessels of peripheral nerve trunks (vasa nervorum) dilate following capsaicin-induced inflammation or local nerve trunk injury. In previous work, we observed that morphine blocked capsaicin-induced dilation of vasa nervorum presumably through the action of local opioid receptors. In the present work, we studied injury-related hyperemia of the rat sciatic vasa nervorum using laser Doppler and hydrogen clearance microelectrode measurements of local perfusion. Systemic morphine reversed hyperemia by vasoconstricting both extrinsic and intrinsic microvessels supplying 48-h-old "neuroma" preparations or crush zones of peripheral nerve trunks. Morphine did not constrict microvessels of contralateral uninjured or sham exposed but uninjured sciatic nerves. In contrast to the injured nerves, contralateral uninjured nerves exposed to morphine frequently had a rise in local perfusion, indicating vasodilation. The vasoconstrictive actions of morphine were blocked by pretreatment with naloxone and were not mimicked by saline injections alone. Systemic doses of selective opioid agonists to mu-, kappa-, and delta-receptors also selectively constricted microvessels of injured nerves. Local blood flow in older experimental neuromas at 7 days had partial sensitivity to morphine, whereas at 14 days perfusion flow was not influenced by morphine. Exogenous opioids dampen early but not later inflammatory microvasodilation and could have important influences on the nerve regenerative milieu.

Animals↗
PubMed1997

Mechanisms of inactivation of L-type calcium channels in human atrial myocytes.

We used whole cell patch-clamp and microfluorimetric (indo 1) techniques to measure Ca2+ current through L-type Ca2+ channels (I(Ca)) and Ca2+ transients in human atrial myocytes. During 1-s depolarizing pulses, I(Ca) inactivation was biexponential. The rate of rapid inactivation was slowed by ryanodine and was correlated with the rate of rise of cytoplasmic free Ca2+ concentration (r = 0.80, P < 0.01). Slower-phase I(Ca) inactivation was not affected by ryanodine but was accelerated by increasing the availability of Ca2+ to permeate the Ca2+ channel. Thus Ca2+ released from the sarcoplasmic reticulum (SR) was responsible for most I(Ca) inactivation during the first 50 ms of a depolarization to 0 mV, and thereafter inactivation by Ca2+ permeating the channel predominated. Pure voltage-dependent inactivation had a much slower time course of development (tau > 2 s) and played a smaller role than Ca2+-dependent mechanisms over a duration comparable to that of an action potential. We conclude that human atrial myocytes show both voltage- and Ca2+-dependent I(Ca) inactivation, that Ca2+-dependent mechanisms predominate over the time course of an action potential, and that although both Ca2+ released from the SR and Ca2+ permeating Ca2+ channels play a role, SR-released Ca2+ is particularly important in early, rapid I(Ca) inactivation, whereas Ca2+ permeating Ca2+ channels is more important in the slower phase of Ca2+-dependent inactivation.

Calcium↗
PubMed1997

[The application of auditory brainstem responses in hearing threshold evaluation].

Auditory brainstem responses (ABR) to click stimula-tion are recorded and analyzed in the patient with traumatic injury to ear. The results showed that the hearing loss (conductive hearing loss of sersorineural hearing loss) can be detected by ABR with the stimulation of pure tone in the range of 2000 to 4000 Hz. It is indicated that the ABR would be an useful methods to evaluate the patient's hearing impairment and the disability extent.

Adolescent↗
PubMed1997

[Application of membrane lipid fluidity and superoxide dismutase in differential diagnosis of pulmonary tuberculosis and lung cancer].

OBJECTIVE: To evaluate the application of membrane lipid fluidity and superoxide dismutase (SOD) in differential diagnosis of pulmonary tuberculosis and lung cancer. METHOD: Fluorescence-labeling (DPH) technique was used for detection of membrane fluidity, while biological illumination method for dectection of SOD. RESULT: The membrane lipid fluidity of lymphocytes obtained from broncho-alveolar lavage fluid (BALF) in the pulmonary tuberculosis and lung cancer patients, and the membrane lipid fluidity of carcinoma cells in lung adenocarcinoma and squamous cancer patients were found to be 4.026 +/- 0.722, 38.254 +/- 0.100, 22.557 +/- 3.771 and 32.875 +/- 9.709 respectively, and statistically significant difference was found between pulmonary tuberculosis and lung cancer patients. The contents of SOD were 170.7 mg/L in the pulmonary tuberculosis and 65.4 mg/L in the lung cancer patients, and statistically significant difference was also found between the two groups. The contents of SOD in the mild, moderate and severe tuberculosis patients were 270.8 +/- 4.1 mg/L, 160.2 +/- 1.9 mg/L and 90.4 +/- 1.6 mg/L respectively, and SOD contents decreased with deterioration of clinical status. CONCLUSION: The membrane lipid fluidity and SOD might be useful biological markers for differential diagnosis between pulmonary tuberculosis and lung cancer.

Adenocarcinoma↗
PubMed1997

[High-malar plasty through an intraoral approach].

Request for high-malar plasty, a purely aesthetic surgery, is fairly common in the Oriental. For an optimal result, consideration should be given to integrating the malar reconstruction with the facial features. A new method for correction of the high-malar deformity was introduced, in which the intraoral approach through an L-shaped incision and osteotomy were employed. The technique is simple, safe and can be done with local anesthesia on an outpatient basis. From December 1994 to February 1996, we have successfully treated 25 cases with this method. Postoperative follow-up for 6 months to 1 year revealed aesthetically satisfactory results. Complications are minor, including swelling, ecchymosis, etc. We conclude that high-malar plasty through the intraoral approach is a safe, effective and relatively simple technique for mild and moderate high-malar deformity.

Adult↗
PubMed1997

[Study on the inclusion compound of phyllostachysin A and DMF].

The crystal structure of inclusion compound phyllostachysin A[1] and DMF, C20H26O6.C3H7ON, was determined by X-ray diffraction. A colorless block crystal with dimensions of 0.6 x 0.6 x 0.8 mm was used for analysis. It shows orthorhombic, and it's space group is P2(1)2(1)2(1) with a = 10.895(3), b = 13.237(2), c = 15.373(3) A, V = 2217.0(3) A3 Z = 4, Dc = 1.302 g cm-3. Direct method was applyed to determine the structure, and the parameters were refined by least square method. The final Rf factor is 0.060 and Rw = 0.083. The result shows that the crystal is formed by Phyllostachysin A and DMF by inclusion interaction.

Antineoplastic Agents, Phytogenic↗
PubMed1997

[Study on antitumor drug-induced apoptosis in human cancer cells by terminal deoxynucleotidyl transferase assay].

OBJECTIVE: Considerable evidence has showed that apoptosis is involved in both cancer development and inhibition. A new assay (terminal deoxynucleotidyl transferase assay, TdT assay) was recently reported to have advantages in the detection of apoptosis. In this study, this assay was used to investigate antitumor drug-induced apoptosis in human cancer cells. METHODS: TdT assay, DNA gel electrophoresis, electron and light microscopy were used to observe apoptosis. RESULTS: Our results showed that cisplatin-induced apoptosis in both HL-60 and SV40T-transformed human bronchial epithelial cells was detected with a good dose and time response. The occurrence of the apoptosis was preceded by the decrease of bcl-2 mRNA expression. With TdT assay, apoptotic cells were observed in the ovarian tumor of patients treated with carboplatin. CONCLUSION: TdT assay may be applicable to moniter apoptosis in human cancers induced by chemotherapy, and to evaluate tumor cell response during treatment.

Antineoplastic Agents↗
PubMed1997

[Determination of arbutin in the herbs of Vaccinium vitis-idaea L. by RP-HPLC].

Determination of arbutin in the herbs of Vaccinium vitis-idaea has been carried out by RP-HPLC, using Inertsil-ODS column (4.6 mm x 250 mm) and mobile phase of methanol and water (15:85), and detecting at 280 nm wavelength. The average content of arbutin is 4.44%, RSD = 2.93%; the recovery rate is 100.7%, RSD = 2.85%.

Arbutin↗