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Biomedical subjects

D Y Yang

Publications and source records attributed to D Y Yang.

At least 19 recordsLinked to original sources
PubMed2005

Reduction of blood pressure with calcium and potassium supplementation in children with salt sensitivity: a 2-year double-blinded placebo-controlled trial.

An investigation of the reductive effect of blood pressure and increment of urinary sodium excretion with calcium and potassium supplementation in children with sodium sensitivity is conducted. In total of 261 school children who had completed a 2-year double-blinded, placebo-controlled trial with calcium and potassium supplementation salt sensitivity, with a salt volume expansion and contraction protocol, was determined. The results showed that in children with salt sensitivity, the increase in blood pressure in the supplementary group was lower by 4.3/4.8 mmHg than that in the placebo group (P<0.05), while no significant change was found between the supplementary group and placebo group in children with nonsalt sensitivity. With calcium and potassium supplementation, the night urinary sodium excretion in children with salt sensitivity was significantly increased (P<0.01), and it is negatively correlated with the increase in blood pressure. It was suggested that a moderate increase of calcium and potassium intake in children with salt sensitivity, through interaction with sodium, can promote urinary sodium excretion and may play contribute to the prevention of hypertension.

Blood Pressure↗
PubMed2003

Pharmacokinetics of ivermectin in the yak (Bos grunniens).

The yak (Bos grunniens) belongs to the cattle family Bovidae and lives in the mountains of China and adjacent areas. Due to the physiological adaptations of yak to its environment and the lack of data, the ivermectin pharmacokinetic was studied following a single subcutaneous dose at the recommended dose for cattle (0.2 mg kg(-1)). The observed peak plasma concentration (Cmax) was 48.93 ng ml(-1) and the time to reach Cmax (Tmax) was 0.73 day. These results show a faster rate of absorption than in cattle. The values for the absorption half-life (t(1/2a)), the distribution half-life (t(1/2alpha)) and the terminal half-life (t(1/2beta)) were 0.31, 0.74 and 4.82 days, respectively. The calculated area under the concentration-time curve (AUC) was 146.2 ng day ml(-1) and the mean residence time (MRT) was 3.57 days. The availability of ivermectin appears low in yaks in comparison to cattle but equivalent to that reported in horses and is likely to be due to physiological characteristics of this species.

Absorption↗
PubMed2001

Systemic administration of a water-soluble hexasulfonated C(60) (FC(4)S) reduces cerebral ischemia-induced infarct volume in gerbils.

Buckminsterfullerence and its derivatives have recently been shown to exhibit considerable in vivo biological activities. A water-soluble hexasulfonated C(60) (FC(4)S) has been shown to protect against oxidative stress. Neuroprotective effects of FC(4)S were investigated in the present study. Focal cerebral ischemia was produced by a permanent occlusion of the right middle cerebral artery in gerbils. Infarct volumes were determined by 2,3,5-triphenyltetrazolium chloride transcardiac perfusion 24 h after cerebral ischemia. Chronic pretreatment of FC(4)S (0.5 and 5.0 mg/kg/day, intraperitoneally for 2 weeks) significantly reduced the infarct volume (by 42% and 68%, respectively) when compared to that of the control group. Results revealed that chronic pretreatment of FC(4)S may protect the brain against focal cerebral ischemia.

Animals↗
PubMed2001

Dynamic scaling theory for a tethered membrane in solution.

We present the dynamic scaling behavior for the specific viscosity and diffusion coefficient of a single membrane and membranes with nonzero concentration in solution. Starting from the membrane free energies, we derive their Langevin equations. The corresponding Kirkwood diffusion equation, describing the time evolution in configuration space, contains two kinds of time scales that are separated by the external dimension 4/(2-D) where D is the dimension of the internal space. These time scale separation behaviors depend strongly on the hydrodynamic screening effect. For a single membrane solution, we resolve the dynamic scaling exponents for the diffusion coefficient and intrinsic viscosity by the dimension reduction method. For a concentrated membrane solution, the effective excluded volume strength and draining parameter are introduced. The effective medium argument is applied to obtain a concentration dependent power law form for the specific viscosity and diffusion coefficient, whose results contribute to a fundamental understanding of membrane in solution and of hydrodynamic screening and excluded volume effects in many different solvents.

Journal Article↗
PubMed2001

Simultaneous monitoring of extracellular glucose, pyruvate, lactate and glutamate in gerbil cortex during focal cerebral ischemia by dual probe microdialysis.

The aim of this study was to monitor dynamic changes in energy-related metabolites in the cortex of gerbils subjected to cerebral ischemia by a dual probe microdialysis technique. Focal cerebral ischemia was produced in anesthetized gerbils by occlusion of the right common carotid artery and the right middle cerebral artery for 60 min. Two microdialysis probes were inserted into both sides of the cortex to simultaneously monitor extracellular glucose, lactate, pyruvate and glutamate. Dynamic and comparative changes in these analytes, on the ipsilateral and contralateral sides of the brain, were simultaneously monitored by liquid chromatography and a microdialysis analyzer. The present study demonstrated decreases in glucose and pyruvate, increases in lactate and glutamate on the ipsilateral side whereas all analytes remain constant on the contralateral side of cortex during cerebral ischemia. In vitro recovery of each microdialysis probe was performed to ensure the quality of experiments. The detection limits of pyruvate, glutamate, lactate and glucose were 0.2, 1.0, 2.0 and 20 microM, respectively. The intra- and inter-assay correlations were less than 5% in standard mixtures and pooled brain dialysates.

Animals↗
PubMed2001

Simultaneous monitoring of extracellular glucose, pyruvate, and lactate in rat testies during ischemia: a microdialysis study.

A dual-probe microdialysis technique was developed for the simultaneous monitoring of glucose and related metabolite levels during testicular ischemia in rats. The determinations of lactate and pyruvate were achieved by liquid chromatography within 5 min. Glucose was determined by a microdialysis analyzer. A unilateral ligation was produced by occlusion of the right artery for 2 or 4 h in anesthetized rats. Microdialysis probes were inserted in both sides of the testis to simultaneously monitor glucose, lactate and pyruvate during basal, ischemia and reperfusion periods. Dynamic and comparative changes in these analytes in ipsilateral and contralateral testes were demonstrated. The present technique can be used as a tool for exploring energy related metabolites and their relationships in testicular ischemia.

Animals↗
PubMed2001

Efficacy of endoscopic isotonic saline-epinephrine injection for the management of active Mallory-Weiss tears.

Therapeutic endoscopy with isotonic saline-epinephrine (ISE) injection is a convenient and widely used procedure for hemostasis in upper gastrointestinal bleeding. We retrospectively evaluated 36 patients (from January 1996 to April 1999) who had been diagnosed with recent or active bleeding due to Mallory-Weiss tears in emergency endoscopic examination. The endoscopic hemostatic method with ISE injection was performed in 15 of 36 patients. The other 21 patients received conservative treatment with hemodynamic support. Patient's clinical data, laboratory data, transfusion requirements, endoscopic findings, and length of hospital stays were evaluated. Initial hemoglobin was significantly lower in the ISE group than the conservative treatment group (9.74 +/- 2.86 g/dL vs. 12.57 +/- 2.80 g/dL, respectively; p < 0.01). Mean transfusion requirements were significantly higher in the ISE group than the conservative treatment group (7.26 +/- 8.78 units vs. 2.85 +/- 6.21 units, respectively; p < 0.1). Patients in the ISE group were supposed to be having a more severe bleeding episode. Most patients achieved initial hemostasis in the ISE group and the conservative treatment group (93% and 95%, respectively). The rebleeding rate was also similar in both groups (1 in 15 in the ISE group and I in 21 in the conservative treatment group). There was no significant difference in length of hospital stay and rebleeding between these two groups (3.47 +/- 1.92 days vs. 2.47 +/- 1.47 days, respectively: p = 0.89). The endoscopic ISE injection is an inexpensive, simple, convenient therapeutic method and it can achieve initial hemostasis for active Mallory-Weiss tears.

Adult↗
PubMed2001

Fatal poisoning by butachlor and chlornitrofen ingested from a bottle marked as nitrofen.

Nitrofen has been banned in Taiwan since January 1, 1983 due to its tetrogenicity. A 78-y-o female consumed about 500 ml of herbicide, labeled as nitrofen, in a suicide attempt. Consciousness disturbance occurred immediately. After 9 h, bloody-tarry stool was noted. Hematemesis occurred 19 h later. Hepatotoxicity and nephrotoxicity also developed. Twitching of head and both upper extremities lasting 20-30 sec and up to 5 min developed on day 3. Sometimes an upward gaze with the face turned to the right or a convulsion of the right upper extremity was observed. EEG showed alpha coma, generalized slow spike-and-wave complexes, and isolated generalized sharp waves mainly in the left occipital area. On day 7, endotracheal intubation was performed due to apnea; she expired on day 9. The pesticide was found to contain butachlor and chlornitrofen. The Agricultural Committee prohibited the marketing of chlornitrofen due to its generation of tumors in animals. The combination of butachlor and chlornitrofen can result in consciousness disturbance, leucocytosis, gastrointestinal hemorrhage, rhabdomyolysis, hypocalcemia, hypoalbuminemia, elevated amylase, nephrotoxicity, hepatotoxicity, seizures and death. The cytotoxicity of butachlor may be related to the patient's death. Active components of pesticides should be checked if the clinical course of a poisoned patient is unusual to allow appropriate interventions.

Acetanilides↗
PubMed2001

Snakebite complicated with Vibrio vulnificus infection.

Snakebite may be complicated with bacteria infections, most of which are Gram-negative bacillus. Snakebite complicated with Vibrio vulnificus infection has not been reported previously. Vibrio vulnificus infection is characterized by a necrotizing wound infection similar to the local lesion of severe snakebite. In Vibrio infections, aggressive debridement with the administration of strong antibiotics as early as possible is the only effective treatment. We report a 79-y-o man who suffered from snakebite on the right palm with rapid progression of hemorrhagic bulla, necrotizing fasciitis, compartment syndrome, and septic shock. Vibrio vulnificuswas cultured from necrotic tissue after aggressive debridement and fasciotomy. The patient recovered from antibiotic treatment and several courses of reconstruction surgery. Severe bacteria infection, such as caused by Vibrio vulnificus, should be considered in snakebite cases refractory to antivenin dosage.

Aged↗
PubMed2001

Hemolysis, elevated liver enzymes, and low platelet count (HELLP) syndrome with acute cortical blindness.

The coincidence of hemolysis, elevated liver enzymes, and low platelet count (HELLP) syndrome and cortical blindness is an uncommon but very dramatic event. We describe a case of HELLP syndrome complicating with acute cortical blindness before delivery. A 27 year-old woman, gravida 1, para 0, with normal medical history, was referred to our emergency department at the 33th week of gestation due to headache, vomiting, and blurred vision. The ophthalmologic examination showed intact pupillary light reflexes and normal ophthalmoscopic findings, but no light perception in either eye. Brain computed tomography showed normal findings. HELLP syndrome and preeclampsia was diagnosed based on the findings of hypertension and proteinuria as well as laboratory data. Prompt delivery was performed in order to achieve good maternal and neonatal outcomes.

Acute Disease↗
PubMed2001

Acute myocardial infarction caused by aortic dissection.

Clinical presentation of aortic dissection is similar to that of acute myocardial infarction (AMI). Clinical differential diagnoses from lethal chest pain in emergency department include AMI, aortic dissection, pulmonary embolism, tension pneumothorax, etc. Thrombolytic therapy for recanalization of thrombotic occluded coronary artery in AMI must be considered, but it is absolutely contraindicated for aortic dissection. However, AMI secondary to aortic dissection is a rare condition, which might be caused by compression of the coronary arteries by a hematoma or extension of the dissection into the coronary arterial wall. Surgery is the first choice for AMI secondary to aortic dissection caused by extension of dissection into the coronary arterial wall. We present a case of inferior wall AMI caused by type I aortic dissection with presentation of chest pain and hemiparaplegia of right lower limb.

Aortic Diseases↗
PubMed2000

Dynamical principles in biological processes: a model of charge migration in proteins and DNA.

The generalized master equations (GMEs) that contain multiple time scales have been derived quantum mechanically. The GME method has then been applied to a model of charge migration in proteins that invokes the hole hopping between local amino acid sites driven by the torsional motions of the floppy backbones. This model is then applied to analyze the experimental results for sequence-dependent long-range hole transport in DNA reported by Meggers et al. [Meggers, E., Michel-Beyerle, M. E., & Giese, B. (1998) J. Am. Chem. Soc. 120, 12950-12955]. The model has also been applied to analyze the experimental results of femtosecond dynamics of DNA-mediated electron transfer reported by Zewail and co-workers [Wan, C., Fiebig, T., Kelley, S. O., Treadway, C. R., Barton, J. K. & Zewail, A. H. (1999) Proc. Natl. Acad. Sci. USA 96, 6014-6019]. The initial events in the dynamics of protein folding have begun to attract attention. The GME obtained in this paper will be applicable to this problem.

Base Sequence↗
PubMed2000

SAR studies of 2-o-substituted-benzoyl- and 2-alkanoyl-cyclohexane-1,3-diones as inhibitors of 4-hydroxyphenylpyruvate dioxygenase.

Inhibition studies of 4-hydroxyphenylpyruvate dioxygenase (HPPD) with various synthesized 2-o-substituted-benzoyl- and 2-alkanoyl-cyclohexane-1,3-diones suggest that the presence of a strongly electronegative group at the ortho position and the conformation of the benzene ring moiety on the benzoylcyclohexane-1,3-dione inhibitors are crucial for potent HPPD inhibition.

4-Hydroxyphenylpyruvate Dioxygenase↗
PubMed2000

Determination of catecholamines in pheochromocytoma cell (PC-12) culture medium by microdialysis-microbore liquid chromatography.

An in vitro microdialysis system was constructed for the measurement of catecholamines in pheochromocytoma cell culture medium. The novel microdialysis device is composed of a petri dish, a dialysis membrane and two transmission tubes. The dialysis membrane is located in the space of a petri dish such that it is immersed in the culture medium. Catecholamines contained in the culture medium diffused into a designed dialysis membrane with sufficient recovery (about 60%). Dialysates were collected by a sampling loop and introduced by an on-line injector to a microbore liquid chromatographic system for analysis of catecholamines. This assay yielded a detection limit of 0.2-0.5 pg/injection with acceptable intra- and inter-assay reproducibilities in 5 microl of dialysates. To evaluate the on-line microdialysis system, PC-12 cells were cultured in a petri dish within an incubator. The baseline concentration of dopamine in PC-12 cell culture medium was about 0.29 ng/ml which was elevated to 2.43 ng/ml after treatment with 0.5 mM potassium cyanide. In conclusion, the present microassay provides for the sensitive, direct measurement of catecholamines in culture medium while minimizing pretreatment procedures for sample preparation.

Animals↗
PubMed2000

Charge conductivity in peptides: dynamic simulations of a bifunctional model supporting experimental data.

Our previous finding and the given mechanism of charge and electron transfer in polypeptides are here integrated in a bifunctional model involving electronic charge transfer coupled to special internal rotations. Present molecular dynamics simulations that describe these motions in the chain result in the mean first passage times for the hopping process of an individual step. This "rest and fire" mechanism is formulated in detail-i.e., individual amino acids are weakly coupled and must first undergo alignment to reach the special strong coupling. This bifunctional model contains the essential features demanded by our prior experiments. The molecular dynamics results yield a mean first passage time distribution peaked at about 140 fs, in close agreement with our direct femtosecond measurements. In logic gate language this is a strongly conducting ON state resulting from small firing energies, the system otherwise being a quiescent OFF state. The observed time scale of about 200 fs provides confirmation of our simulations of transport, a model of extreme transduction efficiency. It explains the high efficiency of charge transport observed in polypeptides. We contend that the moderate speed of weak coupling is required in our model by the bifunctionality of peptides. This bifunctional mechanism agrees with our data and contains valuable features for a general model of long-range conductivity, final reactivity, and binding at a long distance.

Computer Simulation↗