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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
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↗
PubMed1999

Rapid on-line microdialysis hyphenated technique for the dynamic monitoring of extracellular pyruvate, lactic acid and ascorbic acid during cerebral ischemia.

Rapid on-line microdialysis coupled with liquid chromatography was developed for the continuous monitoring of brain neurochemicals during cerebral ischemia. Isocratic separation of these analytes was achieved within 3 min, hence, over 80 analyses could be performed in a 4-h experiment. The dead volume of the microdialysis system was estimated to be less than 10 microl. The detection limits of the present assay, at a signal-to-noise ratio of five, were 2.0, 0.2 and 0.5 microM, for lactic acid, pyruvate and ascorbic acid, respectively. To validate this assay, a transient ischemia was produced by occlusion of two common carotid arteries for 10 min in an anesthetized gerbil. A microdialysis probe was inserted into the striatum of the gerbil to simultaneously monitor pyruvate, lactic acid and ascorbic acid during cerebral ischemia. Significant and dynamic changes in these analytes could be resolved in 3-min intervals. This rapid assay can be used as a tool to study dynamic changes in neurochemicals of the brain, such as during cerebral ischemia.

Animals↗
PubMed1999

Design and synthesis of 3-fluoro-2-oxo-3-phenylpropionic acid derivatives as potent inhibitors of 4-hydroxyphenylpyruvate dioxygenase from pig liver.

Several rationally designed analogs of 3-fluoro-2-oxo-3-phenylpropionic acid were chemically synthesized, and the reactions of the hydrate form of these compounds with 4-hydroxyphenylpyruvate dioxygenase from pig liver as inhibitors were examined. Compounds 14a and 14b were found to be potent competitive inhibitors of the enzyme with Ki values of 10 and 22 microM, respectively.

4-Hydroxyphenylpyruvate Dioxygenase↗
PubMed1999

Acute basagran poisoning mimicking neuroleptic malignant syndrome.

A 27-year-old robust man, without any medical and surgical history, attempted to commit suicide by consumption of 300 cc (44.1%, 132.3 g) basagran, a readily available herbicide. This poisoning resulted in vomiting, fever, sweating, pipe-like muscle rigidity, sinus tachycardia, drowsiness, leukocytosis, rhabdomyolysis and hepatorenal damage. Emperical treatment with bromocriptine was temporally associated with resolution of above signs and symptoms. His clinical presentations and the effect of bromocriptine may be indicative that basagran poisoning mimicks neuroleptic malignant syndrome.

Adult↗
PubMed1999

Clinical impact of upper gastrointestinal tract injuries in glyphosate-surfactant oral intoxication.

Fifty patients with glyphosate-surfactant oral ingestion were studied with upper gastrointestinal (UGI) endoscopic grading using Zargar's modified grading system for mucosal corrosive injury. Esophageal injury was seen in 68% of the patients, gastric injury in 72%, and duodenal injury in 16%. There were no grade 3 injuries. The upper gastrointestinal tract injuries caused by glyphosate-surfactant were minor in comparison with those by other strong acids. The WBC count, amount of glyphosate-surfactant ingested, length of hospital stay and the occurrence of serious complications increased markedly in the group which had grade 2 esophageal injuries. Thus, the severity of the esophageal injuries may be a prognostic factor for the patient with glyphosate-surfactant ingestion. The UGI endoscopy may be indicated for grading esophageal injury in patients who have ingested glyphosate-surfactant in amounts greater than 100 ml. Physicians should pay more attention to the patients with grade 2 or 3 esophageal injuries to prevent serious complications and to provide aggressive supportive care.

Administration, Oral↗
PubMed1998

Technical note: improved DNA extraction from ancient bones using silica-based spin columns.

We describe a simple method for extracting polymerase chain reaction-amplifiable DNA from ancient bones without the use of organic solvents. Bone powders are digested with proteinase K, and the DNA is purified directly using silica-based spin columns (QIAquick3, QIAGEN). The efficiency of this protocol is demonstrated using human bone samples ranging in age from 15 to 5,000 years old.

Animals↗
PubMed1998

Prognostic implications of hyperkalemia in toad toxin intoxication.

The toad possesses several toxic substances. Toad toxin poisoning manifests itself primarily with digitalis-like, cardioactive effects which results in bradycardia, varying degrees of atrio-ventricular block, ventricular tachycardia, ventricular fibrillation and sudden death. We report a cluster poisoning in a family who became intoxicated after ingestion of cooked toad soup for a skin problem. The youngest one (15 months old) died of refractory bradydyarrhythmias soon after arriving at our hospital. A second child (20 months old), who survived, arrived in shock with hyperkalemia (potassium 7.3 mEq/ L) and varying degrees of atrio-ventricular block. She was successfully treated with atropine, lidocaine, and cardioversion, and had a transvenous temporary pacemaker implanted for 1 day. The third boy (16 years old) had hyperkalemia (potassium 6.3 mEq/L) and bradycardia. The remaining three adults had only mild symptoms of nausea, vomiting, watery diarrhea and a sensation of numbness over their oral mucosa. We found that the level of serum potassium had prognostic implications in toad intoxication. Determination of serum potassium level is readily available in almost every hospital and is therefore more convenient to measure than serum digoxin level. We conclude that if hyperkalemia develops, the treatment of toad intoxication must be more aggressive to prevent mortality.

Adolescent↗
PubMed1998

Unique cerebral dysfunction following triphenyltin acetate poisoning.

1. In animal studies, TPTA was found to be neurotoxic. In humans, variable CNS pictures have been described with or without significant EEG findings. Brain CT does not usually reveal any abnormalities. 2. Our patient presented with intermittent unique spontaneous involuntary movement of hands, facial twitching, silly smile and crying. Diplopia, drowsiness, giddiness, vertigo, bidirectional nystagmus, impairment of calculation ability, as well as disorientation to time, people and place also developed. EEG showed mild cortical dysfunction without seizures. MRI and Tc-99m HMPAO brain SPECT revealed no significant findings. TPTA may cause cellular dysfunction of brain without structural damage, which results in variable CNS clinical presentations. 3. Nadir of leucopenia was noted on the sixth day after consumption of TPTA. Liver impairment occurred on the ninth day. Borderline demyelinated neuropathy developed on the fifty-third day. CNS abnormalities, delayed peripheral neuropathy, hepatitis and leucopenia deserve monitoring for a prolonged period, even when the victim initially presents with GI upset only after consumption of TPTA.

Adult↗
PubMed1998

Formation of heterocyclic amines in cooked chicken legs.

The effects of frying and microwave cooking on generation of heterocyclic amines (HAs) in chicken legs with skin and without skin were studied. Chicken legs were microwave-cooked at 2,450 MHz for 5, 10, and 15 min with an output power of 700 W. Frying of chicken legs was conducted at 100 and 150 degrees C for 15 min and at 200 degrees C for 5, 10, and 15 min. The various HAs were analyzed by HPLC with diode-array detection. Results showed that both the varieties and contents of HAs and the weight losses of chicken legs increased along with increasing cooking temperature and time. With skin both the amounts of HAs and weight losses of chicken legs were less than those without skin under the same heating conditions. The weight losses of microwave-cooked chicken legs were higher than those of fried chicken legs. The formation of the aminomethylimidazoquinoline type of HAs could be reduced by choosing microwave cooking in place of frying. Frying led to the formation of both the aminomethylimidazoquinoline and the carboline types of HAs.

Amines↗
PubMed1998

Calcium oxalate is the main toxic component in clinical presentations of alocasis macrorrhiza (L) Schott and Endl poisonings.

Alocasia macrorrhiza (L) Schott and Endl is called Hai Yu, Tien Ho, Shan Yu, Kuan Yin Lien, Tu Chiao lien, Lao Hu Yu and Lang Du in Chinese. Its common English name is Giant Elephant's Ear. The toxic effects of A macrorrhiza arise from sapotoxin and include gastroenteritis and paralysis of the nerve centers. From 1985 to 1993 all individuals who called the Poison Control Center asking for information regarding macrorrhiza were included in this retrospective study. A questionnaire filled out by the Poison Control Center staff collected the demographic data of the victim, the reason for consumption, the prescribed part, clinical symptoms and signs of the victim, and medical outcome of poisonings. Among 27 cases of A macrorrhiza poisoning, the age was 1.5 to 68 y with 12 females and 15 males. One had skin contact and 1 had eye contact. In the 25 cases that consumed the plant leaf or tuber either raw or cooked, the primary symptom was in injected sore throat and the secondary symptom was numbness of the oral cavity. Some patients had salivation, dysphonia, abdominal pain, ulcers of the oral cavity, difficulty in swallowing, thoracodynia, chest tightness and swollen lips. We believe the presence of sapotoxin alone is not sufficient to explain the injected swollen and ulcerative lesions. Calcium oxalate is reported distributed in the entire plant and results in inflammation of the oral cavity and mucous membranes just as our patients had.

Adolescent↗
PubMed1998

Intracerebral hemorrhage in a young woman with arteriovenous malformation after taking diet control pills containing phenylpropanolamine: a case report.

Administration of phenylpropanolamine (PPA) is a rare cause of intracerebral hemorrhage. We present the case of a young female patient with arteriovenous malformation who suffered an intracerebral hemorrhage after ingestion of diet pills containing PPA. The literature on PPA-related intracerebral hemorrhage is also reviewed. This is the first report of PPA-associated intracerebral hemorrhage in a patient with pathology-proven arteriovenous malformation of the brain. Because intracerebral hemorrhage may develop as a side effect of PPA when patients take the manufacturer's recommended dose, especially in patients with vascular abnormalities, we conclude that this medicine should be prescribed carefully and patients should be closely monitored by experienced physicians. Furthermore, its use should be contraindicated in patients who have, or possibly have, a family history of vascular abnormalities.

Adult↗
PubMed1996

The effect of thrombolytic therapy on short- and long-term cardiac autonomic activity in patients with acute myocardial infarction.

BACKGROUND: Reduced heart rate variability after acute myocardial infarction is an important risk stratification factor for mortality and life threatening ventricular arrhythmias. In recent years, thrombolytic therapy has revolutionized the therapy of acute myocardial infarction. However, there is little information about the mechanism of the beneficial effect of thrombolysis on cardiovascular mortality. This study was launched to investigate the relationship between thrombolytic therapy and cardiac autonomic activity, and the sequential changes in heart rate variability after acute myocardial infarction. METHODS: From October 1994 to July 1995, all consecutive patients with their first acute myocardial infarction were prospectively enrolled into the study. Patients without contraindication underwent thrombolytic therapy within six hours of the onset of symptoms. Other patients received conventional treatment. Ambulatory electrocardiography (EKG) was recorded on each patient 7, 90 and 180 days after acute myocardial infarction. Heart rate variability in time- and frequency-domain was analyzed. RESULTS: A total of 49 patients, 45 males and 4 females, were included in this study. The short-term heart rate variability (HRV) (seven-day) in the thrombolytic group was significantly higher than in the nonthrombolytic group in SDANN and SDNN. No significant difference in rMSSD, pNN50, LF, HF or LF/HF ratio was found. The location of MI did not influence the short-term HRV following acute myocardial infarction. In patients treated with thrombolytic agent, the follow-up HRV at 90 days and 180 days increased significantly compared to the baseline HRV (seven-day) in SDANN, SDNN, LF and HF bands. For patients without thrombolytic therapy, their follow-up HRV at 90-day and 180-day increased significantly as compared to the baseline HRV (seven-day) in SDANN and SDNN only. After correction of ventricular ejection fraction, the higher short-term (seven day) HRV activities were still present in SDANN and SDNN in patients with thrombolysis as compared to those without. The 90-day and 180-day HRV did not differ between patients with and without thrombolytic agent. Three patients died suddenly during follow-up, and all showed significantly lower values of HRV than the survivors. CONCLUSIONS: The findings of the present study suggest that 1) in patients with uncomplicated AMI, HRV was transiently reduced with progressive improvement within three months after AMI in both those with and without thrombolytic therapy, and 2) patients who had received thrombolytic treatment had more improved HRV early (seven days) after AMI than those who did not. This improvement, independent of the change of left ventricular function, could be associated with the beneficial effect of thrombolytic therapy in patients with AMI.

Adult↗
PubMed1995

Brown-Séquard syndrome associated with Horner's syndrome in cervical epidural hematoma.

STUDY DESIGN: This report analyzed the likely locations of lesions that cause a combination of Horner's and Brown-Séquard syndromes. One must know the anatomic structure of spinal cord and the sympathetic nerve chain. OBJECTIVES: A hypertensive patient had Brown-Séquard and Horner's syndromes after neck trauma. The magnetic resonance imaging and surgical findings showed the correlation between the clinical symptoms and the likely lesion. METHODS: The patient underwent right hemilaminectomy from C2 to C6 with total removal of hematoma. CONCLUSION: The spinal epidural hematoma rarely is a surgical emergency. The patient presented with Brown-Séquard and Horner's syndromes. Magnetic resonance imaging made a rapid and correct diagnosis. The patient received an emergent right hemilaminectomy from C2 to C6 with removal of hematoma and subsequently made a complete recovery.

Brown-Sequard Syndrome↗
PubMed1995

Epidemiological study of head injuries in central Taiwan.

BACKGROUND: Head injury plays a major role in emergency neurosurgery and is the leading cause of neurosurgical mortality at Taichung Veterans General Hospital. Statistical data show that a similar condition exists in other teaching hospitals in the central Taiwan area, which includes more than one-quarter of the entire population and has more than one-third of the total land of Taiwan. A clinical statistical survey of head injuries in this area may provide a better understanding of the realistic situation in Taiwan. Reports on head injuries in Taipei City, Taipei area, and Hualian County are also cited for comparison. METHODS: The present study is based on a cooperative investigation of head injuries by 18 teaching hospitals in central Taiwan from July 1991 to June 1993. All patients received a neurological examination including the Glasgow coma scale (GCS), with recording by 20 Board-certified neurosurgeons. RESULTS: The 7050 cases collected included 5322 hospitalized cases, 1694 cases seen in the Emergency Room, and 34 deaths on arrival. The leading cause of head injuries was traffic accidents (5354 cases, 76.3%). Motorcycles contributed to the highest number of cases (3661, 68.4%); and trains contributed to the lowest number (8, 0.1%). Helmets were used in only 5.2% of 3503 motorcycle accidents. Based on the patients' or families' description in 4835 cases, the leading cause of the accident was careless driving (1180 cases, 24.4%). The 1088 cases of severe head injury were classified with a score less than 8 by the GCS; 498 of them died, or an 86.6% mortality (575 cases). CONCLUSIONS: Traffic accidents are the leading cause of head injuries, and motorcycles contribute to the major part of it in central Taiwan. Similar conclusions can be drawn for other areas including Taipei City, Taipei area, and Hualian County.

Accidents, Traffic↗
PubMed1994

Repeat operations in failed microvascular decompression for trigeminal neuralgia.

For the study of pathogenesis and treatment of recurrent trigeminal neuralgia, we performed 31 repeat operations from among 400 patients with trigeminal neuralgia in the past 10 years. Initially, of these 400 patients, 376 underwent microvascular decompression only, and 24 underwent partial sensory rhizotomy with or without microvascular decompression. Fifty-three patients (14%) had recurrences after microvascular decompression, of which 31 patients underwent repeat operations. Among the repeat operations, there was negative exploration in 16 patients (52%), arterial loop compression in 7 (22%), venous compression in 4 (13%), and Teflon compression or adhesion in 4 (13%). Twenty-one patients had early recurrences within 1 year, and 10 patients had late recurrences. Negative exploration and arterial compression were more likely in early recurrence (P = 0.01). Continuing demyelination might occur in patients with negative exploration, even when adequate decompression had been initially performed. Seventy percent of the patients had no recurring pain by way of partial sensory rhizotomy for negative explorations, redecompression of arterial loops, division of offending veins, or lysis and reposition of Teflon. About half of the patients had positive findings that were amenable without rhizotomy in the repeat operations. A repeat operation for failed microvascular decompression is a good choice if the condition of the patient is tolerant.

Arteries↗
PubMed1994

Allen score in clinical diagnosis of intracranial hemorrhage.

BACKGROUND: Allen score is a validated weighted linear score for clinical distinction between hemorrhagic and ischemic stroke. As the prevalence of hemorrhagic stroke differs between Caucasian and Chinese populations, and the predictive value of any diagnostic score depends greatly on the prevalence of disease being considered, we tried to verify prospectively this score among the Chinese living in Taiwan. METHODS: From 1 April to 31 August 1993, all patients with acute stroke syndrome, who visited the emergency room at Veterans General Hospital-Taichung, were studied prospectively. Clinical features were recorded thoroughly to calculate the Allen score. The diagnosis was all confirmed by computed tomography (CT) of the head. RESULTS: Totally 255 stroke cases were identified. The types of the stroke were cerebral infarction in 186 subjects (73%), cerebral hemorrhage in 64 subjects (25%), and subarachnoid hemorrhage in 5 subjects (2%). Seventy-five cases were excluded because of the lack of clinical details for calculation. Thus, 180 patients were included. When a cut-off of 4 or 24 was taken into account, the sensitivity of Allen score for diagnosing a hemorrhage was 67%, specificity 100%, accuracy 93%, positive predictive value 100%, and negative predictive value 91%. CONCLUSIONS: Although Allen score can be used for epidemiological studies of incidence and outcome in stroke as well as for a first bedside screening to decide the priority of patients for CT, it is not safe enough as a guide for anticoagulant or thrombolytic therapy. Its validity should be verified before use in a given population other than the Caucasian.

Cerebral Hemorrhage↗
PubMed1994

Bromocriptine treatment of postoperative prolactinoma patients.

BACKGROUND: Prolactinoma is the leading cause of pituitary adenoma. It causes amenorrhea in women and impotence in men. Surgical and bromocriptine treatment are the mainstays of therapy in most of the patients with this disease. Determining the outcome for postoperative hyperprolactinemia patients who received bromocriptine treatment was the main purpose of this study. METHODS: Thirty-two patients who received operation for prolactinoma have been investigated. Twenty of them had received bromocriptine treatment before conception, 14 were diagnosed as having macroadenoma and all of them had post-operative hyperprolactinemia. RESULTS: Five patients needed bromocriptine treatment of more than 12.5mg/day to decrease the serum prolactin level. Three patients received radiotherapy postoperatively. Other patients were bromocriptine sensitive. Eight of them had menses restored, and of these, five became pregnant. CONCLUSIONS: Operation can successfully treat most of the patients with microadenoma. If there has postoperative hyperprolactinemia, bromocriptine treatment should be the first choice before radiotherapy.

Adolescent↗