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Biomedical subjects

D Hou

Publications and source records attributed to D Hou.

At least 19 recordsLinked to original sources
PubMed2001

Liquid-filled balloon brachytherapy using (68)Ga is effective and safe because of the short 68-minute half-life: results of a feasibility study in the porcine coronary overstretch model.

BACKGROUND: Liquid-filled balloons for coronary brachytherapy provide significant advantages over solid sources in dose homogeneity but carry the risk of life-threatening radiointoxication after balloon rupture and laboratory contamination in case of a spill. We hypothesized that the positron emitter (68)Ga, with a half-life of only 68 minutes, was well suited to overcome these safety obstacles while providing full therapeutic efficacy. METHODS AND RESULTS: The feasibility, efficacy, and safety of (68)Ga liquid-filled balloon brachytherapy were investigated in the porcine coronary overstretch model. Four groups of 5 balloon-induced coronary lesions were irradiated with 8, 12, 16, and 24 Gy targeted to the adventitia. Ten unirradiated lesions served as controls. Segments treated with 16 or 24 Gy exhibited marked suppression of neointimal proliferation at 28-day follow-up, with quantitative parameters of intraluminal proliferation reduced to <20%. This beneficial effect was not compromised by untoward edge effects. Uninjured but irradiated vessels did not show histological signs of radiation damage. The (68)Ga whole-body dose due to balloon rupture was estimated to be 5 rem/50 mCi treatment activity and compared favorably with that of (188)Re (78 rem/50 mCi). CONCLUSIONS: (68)Ga positron radiation suppresses neointimal proliferation at doses of 16 and 24 Gy. This biological efficacy, coupled with the attractive safety profile, suggests the selection of (68)Ga as an attractive isotope for liquid-filled balloon brachytherapy.

Animals↗
PubMed2001

The selection of a commercial route for the D1 antagonist Sch-39166.

D1 Antagonists have been reported to be potentially useful in a number of therapeutic areas. Sch-39166 is an example of such a selective D1 antagonist. Three different routes based on (1S,2S)-1-phenyl-1,3-propanediol (19), (+)-L-homophenylalanine (27) or trans-(+)-(1R,2R)-2-hydroxy-1-(methylamino)-1,2,3,4-tetrahydronaphthalene (37) were developed for the commercial preparation of Sch-39166. After analyzing each route for the best combination of cost, yield, throughput and efficiency, the synthesis of Sch-39166 starting from 37, which involves the opening of an aziridinium, was selected for optimization into the commercial route.

Benzazepines↗
PubMed2000

Intrapericardial paclitaxel delivery inhibits neointimal proliferation and promotes arterial enlargement after porcine coronary overstretch.

BACKGROUND: Catheter-based intrapericardial (IPC) delivery of therapeutic agents has recently been demonstrated. Paclitaxel is known to inhibit vascular smooth muscle cell proliferation. This study examined the effect of IPC instillation of paclitaxel on neointimal proliferation after balloon overstretch of porcine coronary arteries. METHODS AND RESULTS: Overstretch injury of coronary arteries was followed by IPC administration of micellar paclitaxel at low dose (LD, 10 mg; n=6) or high dose (HD, 50 mg; n=7) or of control micelles (50 mg, n=5). Animals were euthanized 28 days after balloon dilation. Arterial injury indices were no different among the groups. The neointimal area, maximal intimal thickness, and adventitial thickness were significantly reduced in both LD (0.47+/-0.04 mm(2), 0.43+/-0.03 mm, and 0.35+/-0.02 mm, respectively) and HD (0.51+/-0.06 mm(2), 0.42+/-0.03 mm, and 0. 38+/-0.03 mm, respectively) paclitaxel groups compared with the control group (0.79+/-0.07 mm(2), 0.56+/-0.02 mm, and 0.47+/-0.02 mm, respectively; P:<0.001). Meanwhile, the vessel circumference measured at the external elastic lamina of paclitaxel-treated vessels was significantly larger than the control circumference. Apoptotic cells were found in the neointima. The apoptotic cell percentage was not different between the control (1.72%) and LD (2. 31%) groups but was higher in the HD group (7.07%, P:<0.0001 versus control and LD groups). Immunostaining for matrix metalloproteinase-2 revealed concurrent reduction in the HD group compared with the control and LD groups. CONCLUSIONS: IPC space delivery of a single dose of paclitaxel significantly reduces vessel narrowing in this balloon-overstretch model. This effect is mediated by reduction of neointimal mass as well as positive vascular remodeling.

Angioplasty, Balloon, Coronary↗
PubMed2000

Cytotoxic aldehyde generation in heart following acute iron-loading.

Although the mechanism of myocardial failure following acute iron poisoning is not known, excess iron-catalyzed free radical generation is conjectured to play a role. The effects of time (0 to 360 minutes) on total iron concentrations, glutathione peroxidase activity, and cytotoxic aldehyde production in heart of mice (B6D2F1, n = 65) were first investigated following acute iron-loading (20 mg iron dextran i.p./mouse). In a subsequent experiment, the effects of dose (0 to 80 mg iron dextran i.p./mouse, n = 75) on the aforementioned parameters were investigated. Our results show that the concentrations of cytotoxic aldehydes: (1) significantly differ over-time, with corresponding increases in total concentrations of iron (r = 0.93, p < 0.001); and (2) increase parallel to the total dose of iron administered (r = 0.95, p < 0.001). Furthermore, dose-and time-dependent alterations to glutathione peroxidase activity are observed, which is most likely due to an acute up-regulation of the enzyme as an endogenous protective response to increased free radical activity in the heart subsequent to iron-loading. While no single mechanism is likely to account for the complex pathophysiology of acute iron-induced heart failure, our results shown that iron-loading can result in significant free radical generation, as quantified by cytotoxic aldehydes, in heart tissue of mice. This is the first report on the effects of time and dose on cytotoxic aldehyde generation and glutathione peroxidase activity in heart of mice following acute iron-loading.

Aldehydes↗
PubMed2000

Synaptic development is controlled in the periactive zones of Drosophila synapses.

A cell-adhesion molecule fasciclin 2 (FAS2), which is required for synaptic growth and still life (SIF), an activator of RAC, were found to localize in the surrounding region of the active zone, defining the periactive zone in Drosophila neuromuscular synapses. BetaPS integrin and discs large (DLG), both involved in synaptic development, also decorated the zone. However, shibire (SHI), the Drosophila dynamin that regulates endocytosis, was found in the distinct region. Mutant analyses showed that sif genetically interacted with Fas2 in synaptic growth and that the proper localization of SIF required FAS2, suggesting that they are components in related signaling pathways that locally function in the periactive zones. We propose that neurotransmission and synaptic growth are primarily regulated in segregated subcellular spaces, active zones and periactive zones, respectively.

Animals↗
PubMed2000

[Analysis of complications of augmentation mammaplasty in 12 patients].

OBJECTIVE: To reduce complications and to improve the long-term results of augmentation mammaplasty. METHOD: Twelve patients who had complications during a period of 1 to 13 years after augmentation mammaplasty were studied. The fibrous capsule of the breast implant was examined pathologically. RESULTS: 12 patients (15 breasts) were included in the study. Of the nine patients with unilateral augmentation mammaplasty, four had 1 complication; four had 2 complications and one had 3 complications. Of the three patients with bilateral augmentation mammaplasty, two had the same complication, one had 3 complications. Every complication has its pathologic and clinical characteristics. CONCLUSION: Many measures are important for reducing complications including strict surgical manipulation, proper selection of good implants, preferred submuscular insertion, whole capsulectomy for prosthesis rupture or leak and through hemostasis, proper bandage, massage and follow-up et al.

Adult↗
PubMed1999

Cardiac function and cytotoxic aldehyde production in a murine model of chronic iron-overload.

OBJECTIVES: To determine the relationship between the total chronic dose of iron administered, ex-vivo cardiac function and the concentrations of cytotoxic aldehydes in heart tissue of a murine model. METHODS: In the first experiment, 34 male B6D2F1 mice were randomized to receive intraperitoneal injections of 5, 10 or 20 mg of iron dextran for three weeks, or a placebo control. The mice were subsequently randomized to undergo ex-vivo assessment of cardiac function. In the second experiment, free radical generation, quantified by the presence of 20 separate cytotoxic aldehydes, was assessed in heart tissue of 40 mice that were randomized to receive chronic treatment with various concentrations of iron dextran (100 mg to 300 mg total chronic dose administered), placebo treatment with saline, or no treatment at all (baseline). RESULTS: Iron-loaded groups displayed dose-dependent depressions of heart rate, systolic pressure, developed pressure, coronary pressure, -dP/dt and +dP/dt, and increases in diastolic pressure. Monotonic dose-dependent increases in total heart aldehydes were observed in the iron-treated groups (r-0.97, p < 0.0001), whereas no significant differences were observed between baseline or time-placebo control groups. CONCLUSIONS: While no single mechanism is likely to account for the complex pathophysiology of iron-induced heart failure, our findings show that chronic iron-loading in a murine model results in dose-dependent alterations to cardiac function; and results in free radical mediated damage to the heart, as measured by excess concentrations of cytotoxic aldehyde-derived peroxidation products. This is the first description of the effects of excess iron on cardiac function assessed by an ex-vivo Langendorff technique in a murine model of chronic iron-overload.

Aldehydes↗
PubMed1999

Characterization of apoptotic macrophages in atheromatous tissue of humans and heritable hyperlipidemic rabbits.

Apoptotic macrophages are regularly found in atherosclerotic plaques indicating programmed cell death as one of their regulatory controls. The objective of this study was to characterize in more detail apoptotic macrophages in atherosclerotic lesions of humans and heritable hyperlipidemic (HHL) rabbits. Macrophages were immunohistochemically analyzed using antibodies directed against alphaMbeta2-integrins (CD11b/CD18), CD44, major histocompatibility complex (MHC) class I and II, inducible nitric oxide synthase (iNOS), manganese superoxide dismutase (MnSOD), tumor necrosis factor alpha (TNFalpha), p53, c-jun/AP-1 and rabbit macrophages (RAM-11) and the TUNEL (TdT-mediated dUTP nick end labeling) technique. Colocalization studies of human atherosclerotic carotid and aortic tissue showed apoptotic plaque macrophages also being MnSOD-, alphaMbeta2-integrin-, CD44-, MHC class I- and II-, iNOS-, TNFalpha- and p53-immunoreactive. Similar results occurred in atherosclerotic aortas of HHL rabbits. Computer-assisted morphometric analyses revealed a positive correlation of the area density of MnSOD-immunoreactive macrophages with those of alphaMbeta2-integrin- and CD44-immunoreactive ones, but not with those of MHC class I- and II- as well as of RAM-11-immunoreactive macrophages. We conclude that apoptotic macrophages located in atherosclerotic vessel wall are activated, antigen-presenting, integrin-expressing and oxidatively stressed cells. Since all these processes have been demonstrated to cause apoptosis of macrophages in vitro, we propose their potency accelerates the susceptibility of the macrophages to programmed cell death in atherosclerotic lesions.

Animals↗
PubMed1999

40 years' review of intestinal atresia.

OBJECTIVE: To analyze the 40 years' experience of intestinal atresia and to introduce a new design of long-oblique anastomosis for disproportional loops of the intestine. METHODS: A total of 449 cases of congenital atresia of the small intestine were classified into three groups according to the embryopathology: high group (145 cases), including duodenal and high jejunal atresia; middle group (288), including ileo-jejunal atresia; and low group (16), including terminal ileal atresia. To analyze the survival rate and mode of treatment, we assigned the cases into 3 groups according to the year of admission: 1) 1956-1969 (173 cases), under the general pediatric surgical care; 2) 1970-1985 (147), under the specialty neonatal surgical care; and 3) 1986-1996 (129), with additional use of total parenteral nutrition. RESULTS: The ileojejunal atresia group (middle group) had the highest mortality rate (47.6%). The overall mortality rate decreased as the time went by, dropping from 64.7% in the early years down to 18.6% in the recent years, and no hospital death occurred in the recent couple of years. CONCLUSION: Besides the improvement of neonatal surgical techniques, selecting a proper surgical procedure according to the embryopathology is essential to the reduction of mortality. The long-oblique anastomosis is particularly acceptable in China at present for marked disproportional loops.

Anastomosis, Surgical↗
PubMed1998

Apoptosis caused by oxidized LDL is manganese superoxide dismutase and p53 dependent.

Oxidized low density lipoprotein (oxLDL) induces apoptosis in human macrophages (Mphi), a significant feature in atherogenesis. We found that induction of apoptosis in Mphi by oxLDL, C2-ceramide, tumor necrosis factor alpha (TNF-alpha), and hydrogen peroxide (H2O2) was associated with enhanced expression of manganese superoxide dismutase (MnSOD) and p53. Treatment of cells with p53 or MnSOD antisense oligonucleotides prior to stimulation with oxLDL, C2-ceramide, TNF-alpha, or H2O2 caused an inhibition of the expression of the respective protein together with a marked reduction of apoptosis. Exposure to N-acetylcysteine before treatment with oxLDL, C2-ceramide, TNF-alpha, or H2O2 reversed a decrease in cellular glutathione concentrations as well as the enhanced production of p53 and MnSOD mRNA and protein. In apoptotic macrophages of human atherosclerotic plaques, colocalization of MnSOD and p53 immunoreactivity was found. These results indicate that in oxLDL-induced apoptosis, a concomitant induction of p53 and MnSOD is critical, and suggest that it is at least in part due to an enhancement of the sphingomyelin/ceramide pathway.

Apoptosis↗
PubMed1998

[Anatomy and operation of agger nasi ethmoidal cells and frontal recess].

To reduce postoperative recurrency of nasal polyps and sinusitis, the anatomy of lateral wall of nasal cavity was studied in body head. It was found that there was a considerable wide area between the anterior attachment of the middle turbinate and the roof of ethmoidal sinus, just where the agger nasi ethmoidal cells and frontal recess lying. And also the medial wall of agger nasi ethmoidal cell is just above the anterior attachment of middle turbinate. In our operations, the bony structure above the anterior attachment of middle turbinate was resected to open the medial wall of agger nasi ethmoidal cells and the frontal recess, the lesions in them was removed carefully to reobtain a well drainage. 15 cases were followed up for 0.5 to 1.5 years and the result was satisfying.

Adolescent↗
PubMed1998

The synergistic effects of vitamin E and selenium in iron-overloaded mouse hearts.

OBJECTIVES: To determine whether supplementation with vitamin E and selenium can improve myocardial antioxidant defenses in iron-overloaded mouse hearts. INTERVENTIONS: Iron-overload state was created in B6D2F1 mice (n = 20) by daily injection of iron dextran (5 mg intraperitoneally/mouse) for four weeks. The mice were also simultaneously randomly assigned to receive vitamin E (alpha-tocopherol acetate, 40 mg intraperitoneally, n = 5), selenium (sodium selenite, 1 part/million orally, n = 5), both (vitamin E + selenium, n = 5) or iron-only treatment (n = 5). The hearts were harvested for determination of selenium concentration and glutathione peroxidase activity. In a subsequent study, 15 B6D2F1 mice were randomly assigned to receive daily injections of iron (n = 5) or iron and combined antioxidant treatment (vitamin E + selenium, n = 5), or to serve as controls (n = 5) for four weeks. The hearts were harvested for determination of total iron concentrations. MAIN RESULTS: Significantly greater concentrations of heart selenium and glutathione peroxidase activity were observed in groups supplemented with both agents, as opposed to iron-only treated or single supplemented mice. Significantly lower concentrations of iron were found in controls and in those receiving combined iron and antioxidant treatment (vitamin E + selenium) than in iron-only treated mice. CONCLUSIONS: Vitamin E and selenium function synergistically in the myocardium to provide important antioxidant defenses in iron-overload states, including increased concentrations of selenium, increased glutathione peroxidase activity and decreased concentrations of iron.

Animals↗
PubMed1997

Induction of mitochondrial manganese superoxide dismutase in macrophages by oxidized LDL: its relevance in atherosclerosis of humans and heritable hyperlipidemic rabbits.

The objective of the study was to analyze the intracellular antioxidative response of macrophages (Mphi) exposed to increased levels of low density lipoprotein (LDL). We studied manganese superoxide dismutase (MnSOD) and, in part, GSH in cultured human and rabbit Mphi, and in atheromatous arterial tissue of humans and heritable hyperlipidemic (HHL) rabbits. Incubation of human Mphi with oxidized-LDL (ox-LDL) resulted in an induction of MnSOD mRNA production as shown by RT-PCR. MnSOD immunoreactivity (IR) was found to be located in the mitochondria of Mphi. In HHL rabbits, MnSOD activity and GSH concentration were significantly increased in atherosclerotic intima compared to the media of the aorta, but significantly decreased (P<0.01) in larger plaques compared with smaller ones, resulting in a significant inverse correlation of MnSOD activity (r=-0.67, P<0.001) and GSH concentration (r=-0.57, P<0.01) with plaque size. Immunohistology of the atherosclerotic intima revealed MnSOD-IR in Mac-1 (CD 11b/CD 18)-immunoreactive (ir) Mphi of human arteries and, similarly, in RAM-11-ir Mphi of rabbit ones. The relation of MnSOD-ir Mphi decreased with plaque advancement, which is consistent with biochemical findings. Most MnSOD-ir Mphi in atherosclerotic plaques revealed TUNEL-positive nuclei, indicating DNA strand breaks, and p53-IR. We conclude that mitochondrial antioxidants such as MnSOD are induced in Mphi in vitro and in atherosclerotic arteries as a reply to increased mitochondrial oxidation. As normal consequences of an increased oxidative stress due to the exposure to ox-LDL nuclear DNA strand breaks occur, which are suggested to be a signal to increase p53 protein levels. Reactive oxygen species-mediated mitochondrial-dependent pathways are suggested as major contributing pathomechanisms to nuclear damage, which eventually may result in apoptosis. A common response to increased oxidative stress due to modified LDL is presumed in rabbit and human atherosclerotic plaques.

Animals↗