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Biomedical subjects

I C Chen

Publications and source records attributed to I C Chen.

29 records · Page 2Linked to original sources
PubMed1994

Radiofrequency ablation therapy in atypical or multiple atrioventricular node reentry tachycardias.

Electrophysiologic study and radiofrequency ablation therapy were performed in 23 patients with atypical (8 patients) or multiple (15) atrioventricular node reentry tachycardias. Dual pathways with anterograde fast and slow pathway conductions were demonstrated in 16 patients. Studies on retrograde conduction revealed the presence of three different pathways, including fast (15 patients), intermediate (17), and slow (16). The radiofrequency current was applied to the inferior aspect, one-third anterior two-thirds posterior between the His bundle and the ostium of the coronary sinus, of Koch's triangle along the tricuspid annulus in all patients. Application of the current resulted in selective ablation or modification of both retrograde intermediate and slow pathway conductions in 20 patients. In two patients retrograde fast pathway conduction was also modified. Complete atrioventricular block occurred in the remaining patient. Sixteen patients had no induction of tachycardia or echo, 4 had induction of a single echo, and 2 had induction of the slow-fast form tachycardia; one of those 2 patients underwent a second trial and was successful. A median application of 2 was delivered at a power of 25 +/- 5 W and a duration of 18 +/- 4 sec. The total fluoroscopic time was 25 +/- 21 minutes. The anterograde fast pathway conduction was unaffected; the shortest atrial paced cycle length that sustained 1:1 fast pathway conduction was 329 +/- 65 msec and 330 +/- 68 msec before and after ablation, respectively. A follow-up electrophysiologic study was performed in 16 patients 60 +/- 15 days after ablation. Eleven had no induction of tachycardia or echo, and five had induction of < 3 echoes. This study demonstrated that radiofrequency ablation with the inferior approach is effective and safe in atypical or multiple atrioventricular node reentry tachycardias. It resulted in ablation of the slow pathway and retrograde intermediate pathway conduction with preserved atrioventricular conduction.

Adult↗
PubMed1994

Radiofrequency ablation therapy in idiopathic left ventricular tachycardia with no obvious structural heart disease.

BACKGROUND: The feasibility and efficacy of radiofrequency ablation therapy in idiopathic left ventricular tachycardia has not been assessed in a large group of patients. METHODS AND RESULTS: Twenty consecutive patients with idiopathic left ventricular tachycardia and without structural heart disease underwent electrophysiological study, pharmacological interventions with administration of verapamil and adenosine, and radiofrequency ablation therapy. There were 17 men and 3 women with a mean age of 28 +/- 8 years. The QRS configuration during tachycardia was of right bundle branch block and superior axis in 13 patients, indeterminate axis in 6 patients, and right axis in 1 patient. The tachycardia was electrically inducible and responsive to verapamil but not to adenosine. Thirteen patients demonstrated entrainment. Activation and pace-mapping studies disclosed that the tachycardia originated from the inferior apical septum in 15 patients, the midseptum in 4 patients, and the anterior lateral wall of the left ventricle in 1 patient. Radiofrequency ablation was successful in 17 of the 20 patients (85%). The successful ablation sites were characterized by an endocardial activation time 30 milliseconds earlier than the onset of QRS during tachycardia and by a pace-mapping QRS similar to or closely resembling the tachycardia. All patients displayed sharp spikes preceding the local ventricular electrogram at the ablation site. However, these sharp spikes also were noted in 15 control patients and were not specific for this tachycardia; they persisted after ablation. There were no complications. A follow-up of 7 +/- 8 months in the 17 successfully ablated patients showed no symptomatic tachyarrhythmias without medications. Six patients underwent repeat electrophysiological study, and no induction of tachycardia was revealed. CONCLUSIONS: Radiofrequency ablation therapy is effective and safe in patients with idiopathic left ventricular tachycardia. It should be considered as the primary therapeutic modality in these patients.

Adult↗
PubMed1994

Effect of "mood that day" on pharmacists' job and career satisfaction.

We speculated that mood would affect responses to global measures of job and career satisfaction. We randomly selected 692 pharmacists from the Iowa Board of Pharmacy Examiners' mailing list. After two follow-up mailings, 389 questionnaires were received for a usable rate of 56.9%. "Good day" pharmacists were more satisfied with their jobs and careers than "typical day" pharmacists, supporting the contention that global satisfaction indicators reflect affective satisfaction.

Adult↗
PubMed1992

Anterior pretectal nucleus-induced modulatory effects on trigeminal brainstem somatosensory neurons.

This study examined the effects of anterior pretectal nucleus (APT) conditioning stimulation on the activity of 92 functionally identified somatosensory brainstem neurons in the trigeminal (V) subnuclei oralis, interpolaris and caudalis of anesthetized rats. Conditioning stimulation inhibited most of the nociceptive neurons and some of the non-nociceptive neurons; facilitation was observed only in some non-nociceptive neurons. These data indicate that the ATP has modulatory effects on both nociceptive and non-nociceptive V somatosensory neurons.

Animals↗
PubMed1992

Virus-like particles with reverse transcriptase activity associated with Kawasaki disease.

To investigate the etiologic agent associated with Kawasaki disease (KD), we initially established a cocultivation system using concanavalin A (Con A)-stimulated lymphoblastoid cells obtained from each retrovirus-seronegative individual's peripheral blood mononuclear cells (MNCs) cocultivated with each of 1) 40 patients with KD, 2) 10 patients with other viral infection and skin rash, and 3) 10 age- and sex-matched normal controls. Five major findings suggested that virus-like particles with reverse transcriptase (RT) activity are associated with KD. First, RT activity appeared significantly higher on day 12 after the onset of fever in the KD patients than in those with other viral infections and normal controls (dTMP incorporation: 3,645 +/- 248 vs. 434 +/- 50 vs. 412 +/- 46 cpm, P < 0.0001). Second, the RT activity was not endogenous, because the Con A-stimulated lymphoblastoid cells were obtained from the individuals who were negative for retrovirus. Third, virus-like particles (80-100 nm in diameter) by electron microscopy were found in the concentrated pool supernatants of particulate fraction containing RT activity subjected to sucrose density gradient, obtained from KD patients. Fourth, the viral product, a 31.4 kilodalton molecule, was detected by SDS-PAGE after internal labelling (methionine-S35) and density gradient centrifugation. Fifth, using a "retrovirus universal pol gene region" as a primer and the RT-PCR method, a retrovirus-specific band was detected in the cocultivated supernatants obtained from four KD and one AIDS patients but not in patients with rubella or in healthy controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗
PubMed1991

[Versatility of rectus abdominis muscle or myocutaneous flap--report of seven cases].

The rectus abdominis muscle, due to its strategic location in the abdomen with its dual blood supply and wide arc of transposition, is ideally suited to repair defects over the chest, abdomen, groin and perineum. The muscle is generally based on the superior epigastric artery, deep inferior epigastric artery and their associated capillary communications. From September 1989 to September 1990, at Taichung Veterans General Hospital, seven cases were presented utilizing unilateral rectus abdominis muscle or myocutaneous flap for local or free tissue transfer. The recipient areas included abdomen, groin, perineum, lower leg and a penis reconstruction. Of all flaps that survived, one developed minor skin necrosis causing urethral orifice stricture and urethrocutaneous fistula that later required repair. All cases achieved the surgical goals. There was no donor site infection, nor abdominal wall herniation but persisted wound pain in 2 cases was noted during the follow-up period. All patients resumed daily activity without limitation about six weeks postoperatively. The large skin territory with abundant soft tissue offers versatile flap design. The dissection is simple, speedy and straight foreward. The deep inferior epigastric vessels are long and their calibers are suitable for vascular anastomosis. Usually, the donor sites are primary closed. We recommend this flap as one to be considered in reconstruction planning and as a donor material for free tissue transfer.

Adolescent↗
PubMed1989

Inhibitory effect of stimulation of the anterior pretectal nucleus on the jaw-opening reflex.

The anterior pretectal nucleus (APT) has been recently implicated in sensorimotor integration and has been shown to have suppressive influences on tail flick behaviour and on nociceptive responses of spinal dorsal horn neurones in rats. The present study tested the effect of stimulation of the APT on the rat's digastric jaw-opening reflex elicited by orofacial stimuli. Either ipsilateral or contralateral electrical stimulation at histologically confirmed sites within and immediately subjacent to the APT produced a suppression of the reflex that had an onset of 20-30 ms, peaked around 50 ms and lasted for 200-300 ms; in some cases, a brief period of reflex facilitation preceded the onset of inhibition and the inhibition was sometimes followed by a facilitatory period. No prolonged period of suppression induced by electrical stimulation was noted in these anaesthetized rats. The injection of monosodium glutamate at comparable sites within and subjacent to APT induced reflex suppression that lasted several minutes. These findings represent the first documentation of APT-induced modulation in the trigeminal sensorimotor system, but support recent evidence suggesting the involvement of APT in sensorimotor integration and modulation.

Animals↗
PubMed1986

Oral and facial representation in the trigeminal principal and rostral spinal nuclei of the cat.

Transganglionic transport of horseradish peroxidase (HRP) was used to study the patterns of termination of somatic afferent fibers innervating oral and facial structures within the principal nucleus (Vp), nucleus oralis (Vo), and nucleus interpolaris (Vi). The primary trigeminal afferent fibers that innervate the oral cavity supplied by the pterygopalatine, superior alveolar, lingual, buccal, and inferior alveolar branches, as well as the facial skin supplied by the frontal, corneal, zygomatic, infraorbital, auriculotemporal, mylohyoid, and mental branches, were traced in this experiment. The results show that trigeminal afferent nerves that innervate the oral cavity project mainly to the principal nucleus, the rostrodorsomedial part (Vo.r) and dorsomedial division (Vo.dm) of pars oralis, and the dorsomedial region of pars interpolaris, while an extensive overlap of projections is found in the Vo.r, Vo.dm, and rostral Vi. The central processes of fibers innervating the anterior face (i.e., mental, infraorbital, and frontal nerves) terminate in the ventral division of principalis (Vpv), caudal region pars oralis (Vo.c), and ventrolateral Vi, with the largest numbers of terminals being found in the Vpv and Vi. In contrast, the central projection patterns of the corneal, zygomatic, mylohyoid, and auriculotemporal afferents are different from those of other afferent nerves examined, and present a discrete projection to the trigeminal sensory nuclear complex (TSNC). The corneal, mylohyoid, and auriculotemporal afferents mainly project to the restricted regions of principalis and caudal Vi, while zygomatic afferent nerve fibers project to the caudal third of pars interpolaris. The typical somatotopic organization with the face of the mouth open inverted is represented in the rostrocaudal midlevels of the Vpv and caudal pars interpolaris. The Vpd receives topographical projection from primary afferent nerves that innervate the oral structure only, while this projection was organized in a complicated manner. The relationship between the functional segregation and the cytoarchitectonic differentiation of the TSNC is discussed, particularly with respect to this somatotopic organization, combined with the characteristics of projecting cells in the TSNC.

Animals↗
PubMed1986

Oral and facial representation within the medullary and upper cervical dorsal horns in the cat.

Transganglionic transport of HRP was used to study the patterns of termination of somatic afferent fibers innervating oral and facial structures within the trigeminal nucleus caudalis and upper cervical dorsal horn of the cat. In separate animals, the superior alveolar, pterygopalatine, buccal, inferior alveolar, lingual, frontal, corneal, zygomatic, infraorbital, mental, mylohyoid, and auriculotemporal branches of the trigeminal nerve were traced in this experiment. The organization of the primary afferents innervating the oral structures is not uniform across laminae and at different rostrocaudal levels of the nucleus caudalis. The superior alveolar and pterygopalatine nerves mainly terminate in laminae I, II, and V at the level of the rostral one-third of the caudalis. By contrast, the lingual, inferior alveolar, and buccal nerve terminate in laminae I-V of, respectively, the rostral third, the entire length, and caudal two-thirds of the caudalis. In addition, the lingual, buccal, and pterygopalatine nerves terminate in the dorsal and middle parts of the interstitial islands or pockets of lamina I neuropil extending to the rostral levels parallel to the nucleus interpolaris. Mediolaterally, in laminae I, II, and V of the rostral third an extensive overlap of projections was found between the branches from each trigeminal division, and some overlap was observed between projections from the mandibular and maxillary divisions. On the other hand, the projections of primary afferents innervating the facial structures are arranged in a somatotopic fashion in rostrocaudal and mediolateral axes over the laminae (I-IV) through the nucleus caudalis and upper cervical dorsal horn. Fibers from the perioral and perinasal regions terminate most rostrally in caudalis, and fibers from progressively more posterior facial regions terminate at successively lower levels. A mediolateral somatotopic arrangement was observed, with fibers from the ventral parts of face ending in the medial regions and fibers from the progressively more dorsal parts of the face ending in successively more lateral regions of the medullary and upper cervical dorsal horns. Corneal afferent terminals are concentrated in the outer parts of lamina II at the levels of the rostral parts of the caudal two-thirds of the caudalis and the interstitial islands of lamina I. The maxillary division terminates first at the most caudal level of the caudalis, followed by the ophthalmic division descending as far as the C2 segment and the mandibular division reaching the most caudal level of the C2 segment.(ABSTRACT TRUNCATED AT 400 WORDS)

Afferent Pathways↗