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Biomedical subjects

Y C Chang

Publications and source records attributed to Y C Chang.

At least 199 records · Page 11Linked to original sources
PubMed1996

Diagnosis and follow-up of carotid-cavernous fistulas by carotid duplex sonography and transcranial color Doppler imaging.

To investigate the suitability of extracranial carotid duplex (ECD) and transcranial color Doppler imaging (TCDI) in the diagnosis and follow-up of treatment in patients with carotid-cavernous fistulas (CCF), combined ECD and TCDI examinations were studied in seven patients with traumatic CCF. According to angiography, four patients had direct CCF, two indirect CCF and one both direct and indirect CCF. In ECD, hemodynamic parameters of the feeding artery showed an abnormally increased flow volume and decreased resistivity indices in five direct CCFs from the internal carotid artery and one indirect CCF from the external carotid artery. Direct visualization of the CCF was achieved in patients with direct CCF only, and revealed itself as a heterogeneous mosaic flash resulting from high flow velocities and turbulence. Patterns of venous drainage were detected via the transorbital and transforaminal windows in seven and five patients (four direct and one indirect CCF patients), respectively. These abnormal findings were improved or even normalized after successful treatment. In conclusion, combined ECD and TCDI examinations appear to be useful for the diagnosis and follow-up of CCF.

Adult↗
PubMed1996

A solitary congenital self-healing histiocytosis. Report of a case and review of the literature.

Congenital self-healing histiocytosis (CSHH), and especially the solitary variant, is a rare primary skin disorder. We report on a newborn with a congenital solitary ulcerated skin nodule. Extracutaneous involvement was not found. A skin biopsy was performed at the age of 44 days and revealed a dense dermal infiltrate of large histiocytic cells. Immunohistochemical study revealed that the cells of the dermal infiltrate were Langerhans' cells which were strongly positive for S- 100 and negative for lysozyme, leukocyte common antigen and alpha-1-antichymotrypsin. The skin lesion involuted spontaneously over the next month without any treatment. The clinical, histopathological and immunohistochemical results fulfilled the criteria of solitary CSHH. We herein report the first case of CSHH in Taiwan and the twelfth case of solitary CSHH in the world.

Histiocytosis↗
PubMed1996

Observation of bolus position with standardized test foods and fluoroscopic technique.

Sugar and agar balls containing barium were made for the fluoroscopic observation of the bolus position during habitual side chewing in 13 adult males (aged from 20 to 28 years) who had a complete dentition and healthy masticatory system. The test foods had constant size, shape, weight and known hardness, i.e. type 1, 20 kg; type 2, 40 kg; type 3, 1.0 kg and type 4, 0.5 kg. These four types of test foods were chewed randomly in a fluoroscopic room. The jaw separation distance and the bolus position during first bite and crushing bite were observed. The influence of the chewing order of four types of test foods on the bolus position was also recorded. It was found that both hard and soft test foods were most often crushed at the first molar area, and the separation distance during the crushing bite was only slightly wider than the diameter of the food. The first bite jaw separation distance for hard food chewing was significantly wider than soft food chewing and the later in the chewing order the wider the separation distance. The effect of chewing order was not significant on the position and jaw separation distance of the crushing bite.

Adult↗
PubMed1996

Frequency of linear hyperechogenicity over the basal ganglia in young infants with congenital rubella syndrome.

Five young infants with congenital rubella syndrome (CRS) underwent cranial ultrasonographic examinations and/or computed tomographic examinations. Only two of these infants were small for their gestational age, and none of them were microcephalic at birth. Deafness and ocular lesions were found in four patients, and congenital heart disease was found in three. All had abnormal ultrasonographic findings: linear-shaped hyperechogenicity over the basal ganglia was noted for five patients, periventricular punctate hyperechogenicity was noted for three, and subependymal cysts were observed in two. Follow-up ultrasonograms for two of the patients showed progressively enlarging hyperechogenic lesions. Calcification was found in both patients examined by means of computed tomography. All patients became microcephalic, with profound global developmental delay. Intracranial calcifications are common findings in patients with CRS. Ultrasonography should be performed for high-risk neonates, regardless of their symptoms. The finding of linear hyperechogenicity over the basal ganglia should prompt a search for all congenital infections, including CRS.

Basal Ganglia↗
PubMed1996

Catheter ablation of junctional ectopic tachycardia by guarded low dose radiofrequency energy application.

The prognosis of junctional ectopic tachycardia has been poor. A 9-year-old boy with dilated cardiomyopathy and this incessant form of tachycardia underwent RF ablation. Without retrograde atrial depolarization during tachycardia, serials of low dose RF energy were applied near the His-bundle area to find out the arrhythmogenic foci. The optimal site for ablation showed rate acceleration at low dose application and rate slowing down followed by conversion upon increasing the energy. By using this guarded low dose ablation technique, the tachycardia was eliminated without AV block. The LV function also improved.

Cardiomyopathy, Dilated↗
PubMed1996

The second capsule gene of cryptococcus neoformans, CAP64, is essential for virulence.

The extracellular polysaccharide capsule produced by Cryptococcus neoformans is essential for its pathogenicity. We have isolated and characterized a gene, (AP64, which is required for capsule formation. An encapsulated strain created by complementation of the cap64 mutation produced fatal infection of mice within 25 days, while the cap64 acapsular strain was avirulent. Gene deletion of CAP64 from a wild-type strain resulted in the loss of capsule as well as virulence. Contour-clamped homogeneous electric field gel analysis indicates that CAP64 is located on chromosome III which is different from the localization of another capsule-related gene, CAP59. The nonlinkage between CAP64 and CAP59 was also supported by classical recombinational analysis. Database searches did not reveal any sequence with high similarity to CAP64. We also found that the CAP64 locus is contiguous to a convergently transcribed gene which has significant similarity to the gene encoding the yeast proteasome subunit, PRE1. The distance between the cDNA ends of these two genes is only 22 bp. This study confirms the previous molecular genetic evidence that capsule is an essential factor for the virulence of C. neoformans in the murine model.

Amino Acid Sequence↗
PubMed1996

Reverse jugular flow in a case of thrombosis of the brachiocephalic vein with an artificial arteriovenous fistula.

Thrombosis of the thoracic inlet veins following placement of a central venous catheter is a well-known complication, and several findings have been reported by color Doppler sonography. However, reverse jugular flow resulting from this complication is rarely mentioned and should be differentiated from another complication of iatrogenic arteriovenous fistula between neck vessels. The authors here describe a uremic patient with an artificial arteriovenous fistula in the forearm complicated with thrombosis of the ipsilateral brachiocephalic vein. Factors permitting the differential diagnosis by coloer Doppler sonography and clinical conditions are proposed.

Angiography, Digital Subtraction↗
PubMed1996

2-D time-of-flight (TOF) MRA of thrombophlebitis of upper extremity and subclavian veins. A case report.

In this report, the authors present a case of segmental thrombosis of left subclavian vein that was inaccessible to conventional venography and inconclusive in magnetic resonance techniques (spin echo, gradient echo) but was clearly demonstrated by two-dimensional time-of-flight magnetic resonance angiography (2D TOF MRA). This technique is very sensitive to detect slow flow or partial occlusion of the vessels and is of great help in solving the problem of axillary-subclavian venous obstruction or thrombophlebitis.

Adult↗
PubMed1996

Significance of hemoptysis following thrombolytic therapy for acute myocardial infarction.

PURPOSE: To describe the occurrence, cause, and significance of hemoptysis following thrombolytic therapy for acute myocardial infarction. PATIENTS AND METHODS: We retrospectively reviewed 2,634 patients presenting with acute myocardial infarction who received thrombolytic therapy to determine the incidence of hemoptysis. Chart and radiographic review included the type, dose, and route of thrombolytic therapy. In addition, the onset, duration, and severity of hemoptysis were recorded and correlated with radiographic and bronchoscopic findings. RESULTS: Eleven patients (0.4%) developed hemoptysis following administration of thrombolytic therapy for an acute myocardial infarction. The duration and severity had a wide range, although no patient had significant hemodynamic compromise. The source of hemoptysis was identified in only one patient who had a tongue laceration following cardiopulmonary resuscitation, and blood was seen within the oropharynx and trachea. No definitive cause was identified in all other patients. There was no correlation between the different types or doses of thrombolytic therapy and the duration or severity of hemoptysis. Chest radiographs were nonspecific and demonstrated resolution within 11 days following hemoptysis. CT of the thorax in one patient and bronchoscopy in two patients confirmed chest radiographic findings and in no patient was an underlying pulmonary abnormality identified. CONCLUSIONS: Pulmonary hemorrhage and hemoptysis are unusual complications of thrombolytic therapy in patients with acute myocardial infarction. Although hemoptysis may be the first indicator of an underlying pulmonary abnormality, we found no case in which a significant abnormality was unmasked. This study suggests that follow-up chest radiographs are recommended and further evaluation may be unnecessary if complete resolution is demonstrated.

Aged↗
PubMed1996

Pneumothorax after small-bore catheter placement for malignant pleural effusions.

OBJECTIVE: The objective of this study was to evaluate the incidence and significance of pneumothorax after small-bore chest tube placement for symptomatic malignant pleural effusions. SUBJECTS AND METHODS: Over a 2-year period, 90 patients with a known primary malignant tumor and symptomatic pleural effusion were referred to the radiology service at Duke University Medical Center. All patients underwent placement of a small-bore chest tube with fluid drainage in preparation for intrapleural sclerotherapy. Two of these patients were excluded because of coexisting empyema (n=1) and thoracentesis (n=1). The remaining 88 patients (30 men and 58 women; 26-86 years old [mean, 60 years old], who had 90 chest tubes placed, formed our study group. The incidence, duration, and clinical significance of their pneumothoraces and the amount of pleural effusion drained were recorded. RESULTS: Among the 88 patients with 90 chest tubes, 27 patients with 28 chest tubes (31%) were found to have pneumothorax after the procedure. For 23 patients with 24 chest tubes, pneumothorax was evident on chest radiographs taken immediately after tube insertion and fluid drainage. Four patients with four chest tubes were found to have pneumothorax on chest radiographs taken the next day. No significant difference in the amount of fluid drained during the procedure was noted for patients with or without pneumothorax (831 ml versus 853 ml). No relationship between the size of each pneumothorax and the size of each drainage catheter was seen. The duration of pneumothorax ranged from 2 hr to 18 days (average, 3.5 days). Resolution of pneumothorax was seen in 22 (79%) of 28 cases; the remaining six cases of pneumothorax (21%) were stable, and the patients showed eventual fluid reaccumulation after chest tube removal and no sclerotherapy. No patient developed tension pneumothorax, respiratory distress, or other complications. CONCLUSION: Pneumothorax should be recognized as a common finding after chest tube placement and immediate fluid drainage for malignant pleural effusions. We suggest that this finding is related to rapid removal of fluid from a relatively stiff, noncompliant lung. Patients whose lungs do not fully re-expand in several days will probably not benefit from sclerotherapy. Their tubes may be removed without risk of an enlarging tension pneumothorax.

Adult↗
PubMed1996

Detection and sequence analysis of a new herpesvirus-like agent in AIDS and non-AIDS Kaposi's sarcoma in Taiwan.

A new herpesvirus-like DNA sequence (KSHV) has been recently identified in Kaposi's sarcoma from acquired immunodeficiency syndrome (AIDS) and non-AIDS patients. In order to verify the role of this new viral agent in Taiwan, a series of Kaposi's sarcoma specimens obtained from AIDS and non-AIDS patients in three medical centers representing different geographic locations of Taiwan were surveyed. A total of seven specimens from AIDS patients and 22 specimens from non-AIDS patients were tested for the presence of this herpesvirus-like agent by polymerase chain reaction (PCR) using the published Kaposi's sarcoma 330-233 primers. The tumor DNA was also tested for cytomegalovirus (CMV), Epstein-Barr virus (EBV), and human herpes-virus type 6 (HHV-6). The Kaposi's sarcoma specimens from AIDS and non-AIDS patients were positive for KSHV except in one case. Only occasional specimens were positive for CMV and EBV, with a slightly higher positive rate for HHV-6 in AIDS and non-AIDS patients. Cloning and sequence analysis of the PCR products from two cases of Kaposi's sarcoma (one each for AIDS and non-AIDS) revealed only minor differences in this DNA sequence, as compared with the published data from north America. These results further support the assumption that this new KSHV is strongly associated with Kaposi's sarcoma in AIDS and non-AIDS patients in Taiwan.

Acquired Immunodeficiency Syndrome↗
PubMed1996

4(R)- and 4(S)-(5-phenylpentyl)-glutamic acids attenuate excitatory postsynaptic potential on hippocampus without inhibiting postsynaptic NMDA and AMPA receptors.

The electrophysiological effects of 4(R)- and 4(S)-(5-phenylpentyl)-glutamic acids (C5R and C5S analogues) were investigated. In the presence of 5 microM C5R or C5S, excitatory postsynaptic potentials (EPSPs), elicited by stimulating the Schaffer collateral-commissural pathway, recorded in the hippocampal CA1 region on rat brain slices were reduced by more than 50% of the control. Both the NMDA receptor- and the non-MNDA receptor-mediated components of the EPSP were attenuated to the similar extent. The blockade of the presynaptic input, by 0.5 microM tetrodotoxin (TTX), resulted in that C5 analogues no longer inhibited the depolarization induced by AMPA or NMDA on brain slices. On the other hand, the AMPA- and NMDA-induced whole cell inward current of the dissociated hippocampal neurons was not affected by the presence of C5 analogues, investigated with the whole cell patch-clamping technique. These results suggest that the site of the inhibitory action of C5R and C5S may be at the presynaptic termini and that the release of the excitatory neurotransmitter, most likely the glutamate, may be tampered.

Animals↗
PubMed1995

Further analysis of the CAP59 locus of Cryptococcus neoformans: structure defined by forced expression and description of a new ribosomal protein-encoding gene.

Cryptococcus neoformans (Cn) produces an extracellular polysaccharide capsule that is an essential factor for virulence. We previously isolated a gene, CAP59, which is necessary for capsule formation. To dissect the functional region of CAP59, we placed it under control of the Cn GAL7 promoter (pGAL7). Among the several pGAL7::CAP59 fusion constructs, only the one containing the entire open reading frame of CAP59 was able to complement the acapsular phenotype under galactose induction. A missense mutation in the coding region abolished complementation by the fusion construct. We also found that the CAP59 locus is contiguous to a convergently transcribed L27 ribosomal protein-encoding gene (CL27). The distance between the cDNA ends of these two genes is only 25 bp. CL27 has two introns near its N terminus. The translated CL27 protein is 183 amino acids (aa) in length with an estimated molecular mass of 20 kDa, and the first 34 aa at the N terminus may be a targeting peptide for mitochondria. A high degree of restriction-fragment-length polymorphism was detected in the DNA sequence containing CAP59 and CL27.

Amino Acid Sequence↗
PubMed1995

Host effects and sequences essential for accumulation of defective interfering RNAs of cucumber necrosis and tomato bushy stunt tombusviruses.

Passage of cucumber necrosis virus (CNV) containing defective interfering (DI) RNAs through cucumber plants decreased the accumulation of DI RNAs to undetectable levels. Subsequent passages in two Nicotiana species (Nicotiana benthamiana or N. clevelandii) resulted in the appearance of DI RNA species that were larger than the DI RNAs observed during exclusive serial passages of CNV through the Nicotiana species. Sequence analysis of cloned cDNAs corresponding to the two DI RNA populations indicated that the smaller CNV-DI RNAs contained the four conserved regions (I through IV) of the genome typical of tombusvirus DI RNAs, whereas the larger DI RNAs were of similar organization but had a direct repeat of the middle portion of the molecule. This result suggests that the host has an influence on the type of DI RNA that accumulates during consecutive high multiplicity of infection passages. A comparative analysis of deletions targeting the individual conserved regions in both CNV and tomato bushy stunt virus (TBSV) DI RNAs revealed that only region III was completely dispensable for accumulation of either DI RNA species. More refined deletion analyses in regions I and II indicated that smaller segments of 75 and 35 nucleotides (nt), respectively, could be deleted without abolishing infectivity. The dispensable sequences in region II of both TBSV and CNV DI RNAs mapped to the top portion of a putative stem-loop structure. These studies indicate that both essential and nonessential sequences are conserved in DI RNAs. The essential sequences in regions I, II, and IV likely contain important cis-acting elements, whereas nonessential regions such as region III may play secondary roles such as optimally spacing cis-acting elements or maintaining the DI RNA at an overall size that is stable.

Base Sequence↗