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Biomedical subjects

Y Chang

Publications and source records attributed to Y Chang.

At least 289 records · Page 16Linked to original sources
PubMed1990

Evolution of post-natal herpes simplex virus encephalitis to multicystic encephalopathy.

A 3-week-old, previously healthy infant developed biopsy-proven Herpes virus type 2 (HSV-2) encephalitis. The encephalitis was characterized by cells having intranuclear inclusions and was without evidence of inflammation or hemorrhage. Neuroimaging studies did not show any destructive lesions in the brain. In spite of antiviral therapy, the infant's neurological conditions deteriorated, and the patient died at the age of 18 weeks. Post-mortem examination showed that most of the cerebral hemispheres were replaced by multiloculated cystic cavities of various sizes, typical of multicystic encephalopathy (MCE). The cystic lesions were randomly distributed and were not confined to any vascular territory. By light microscopy, there were no features of viral infection in the brain. Although in situ hybridization of the biopsy specimen taken during the acute phase of the disease demonstrated abundant HSV genome, this same method failed to detect HSV on the post-mortem specimen. These findings suggest that HSV-2 can induce MCE. Furthermore, the absence of histological features of viral encephalitis and the failure to demonstrate viral genome in the brain at autopsy does not exclude an infectious etiology in certain cases of MCE.

Autopsy↗
PubMed1990

Primary cutaneous rhabdomyosarcoma.

We report an unusual case of primary cutaneous embryonal rhabdomyosarcoma presenting as a solitary skin lesion on the anterior chest of a 20-month-old child. The tumor was characterized by small, round to oval, poorly differentiated cells. Immunohistochemically, the tumor was negative for NSE, S-100 protein, LCA, and keratin but positive for muscle-specific actin, myoglobin, desmin, and vimentin, thus indicating the presence of myogenous differentiation. Ultrastructural analysis demonstrated thick and thin filaments. Special studies showed no evidence of a primary rhabdomyosarcoma in the patient at a more typical location, nor was there any evidence of metastases.

Humans↗
PubMed1990

Evidence for the exchange of segments between genomes during the evolution of lambdoid bacteriophages.

Heteroduplexes between the DNA molecules of 12 lambdoid phages were analysed by electron microscopy. The positions of the regions of base sequence homology between the DNA molecules divide them into 35 segments, most of which have a number of alternative forms (alleles), which in general must be functionally homologous but which differ in base sequence and length. The positions of the boundaries between segments in phage lambda show that each segment is probably a gene or a group of genes, and that each phage genome is a different combination of the alleles of the segments. The frequency of the occurrence of the different alleles indicates that the total number in the natural population may be small. The different combinations of alleles of separate segments, found among the phages, indicate the exchange of segments between the phages during their evolution.

Alleles↗
PubMed1990

[A scanning electron microscopic investigation of accessory foramina on the pulpal floor of human primary molars. 1].

The pulp chamber floor of 39 primary first and second molars of 10 mandibuiars of the Indian scull was investigated with a scanning electron microscope for the presence of accessary foramens. All of the teeth investigated were in II A stage of Hellman's dental age. The teeth were sectioned with a diamond disk with a point of 1.5 mm apical to the external furcation area, and 5 mm coronal to the cervical line. The teeth were washed with a supersonic washer and dried. The specimens were mounted with the pulpal floor facing upward on an aluminium stub, plated with gold and observed with scanning electron microscope. As a result of this investigation the following conclusions were obtained. 1) Accessary foramens were observed in 4 mandibulars out of 10 mandibulars and in 14 teeth (35.9%) out of 39 teeth. 2) The maximum 10 and minimum one accessary foramen were found with an averrage of 2.8 per tooth. 3) Accessary foramens were observed with high frequency in the central portion of the pulp chamber floor. 4) The diameter of the opening of the accessary foramens of the mandibular first molars were maximum 83 microns, minimum 8 microns and average 45.4 microns. While maximum 51 microns, minimum 15 microns and average 37.3 microns in mandibular second molars. 5) The opening shape of accessary foramens was classified into three types, round 56.4%, oval 28.2% and others 15.4%. 6) Accessary foramen tend to be present bilaterally in the same individual. 7) It seemed that there is an individual difference in the presence or absence of accessary foramen. One individual has many accessary foramens, while another individual lacks accessary foramen.

Child↗
PubMed1990

Specificity of androgen receptors of hepatocellular carcinoma and liver in humans.

The specificity of androgen receptor in hepatocellular carcinoma and the liver was investigated using auto-radiographic techniques. Partial hepatectomy was carried out on 11 patients with hepatocellular carcinoma and associated parenchymal disease of the liver. Androgen receptors were assayed biochemically for hepatocellular carcinoma and the surrounding liver in all cases. Estrogen receptor was also measured in five patients. In eight patients, fresh resected specimens as thick as 3 mm were first incubated for 15 minutes in a medium containing estradiol and hydrocortisone, and then radio-labeled testosterones were added to the medium. After another 60 minutes incubation, macro-autoradiographic studies were carried out. With the same medium and chemicals, and using the same principle, micro-autoradiographic studies were performed using fresh hepatocellular carcinoma and liver cell suspensions in six cases. The radio-labeled testosterones were incorporated into hepatocellular carcinoma and the liver to a parallel extent with the androgen receptor titers biochemically assayed. The current results seem to indicate that androgen receptors present in hepatocellular carcinoma and the liver of humans specifically bind androgens. Further studies are needed to elucidate the role of AR in hepatocarcinogenesis in humans.

Aged↗
PubMed1990

[Results of vascular reconstruction in lower limbs ischemia: a six-year clinical experience].

During the period between Dec. 1982 to Nov. 1988, a total of 412 patients with 471 limbs at risk of peripheral arterial occlusive disease underwent vascular surgical treatment at the Veterans General Hospital. There were 382 men and 30 women, who ranged in age from 20 to 84 years (mean 63.17 +/- 11.85 years). 95 cases were isolated aortoiliac occlusive disease, 94 cases were combined aortoiliac and femoropopliteal disease, 169 cases were femoropopliteal occlusive disease and 54 cases were femorotibialperoneal occlusive disease. Various reconstructive procedures were performed in the these patients. The cumulative limb salvage rate (LSR) exceeded cumulative patency rate (CPR) in all categories and the result of LSR and CPR were 97.6% and 91% for aortoiliac reconstructive surgery in six years, 96% and 77% for above-knee femoropopliteal saphenous vein bypass (SVB) in six years, 79% and 74% for below-knee femoropopliteal SBV and 63% and 34% for femoro-distal SVB in five years. 88% and 76% for above-knee femoropopliteal human umbilical vein (HUV) bypass in four years. 67% and 45% for femoro-distal HUV bypass in three years follow-up period individually. The immediate good symptomatic results of the vascular reconstruction was 88% encountered in isolated aortoiliac disease, 63% in combined aortoiliac and femoropopliteal disease, 70.4% in isolated femoropopliteal disease and only 26% in femorotibial-peroneal disease (FTP). No change symptoms was still higher (33%) in FTP than the other vascular reconstruction due to poor distal runoff in this series. The early postoperative mortality rate was 1.6%, the late mortality rate was 2.7%, the incidence of postoperative complication rate was 13.6%. The major lower limb amputation rate was low as 7% in our series.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Mediastinal radiographic abnormality caused by anomalous venous drainage: how often is it seen in Afro-Americans?

An abnormal superior mediastinal density seen on a chest x-ray led to computerized tomography scan detection of an enlarged azygous vein produced by anomalous embryologic development of the inferior vena cava. This potentially clinically important abnormality is uncommon and statistics indicating its frequency are best available from the Japanese. In addition to alerting clinicians to this abnormality, a plea is made for review of autopsy series in Afro-Americans by pathologists in order to determine potential risks in a variety of surgical procedures.

Aged↗
PubMed1989

Molecular cloning of new human TR2 receptors: a class of steroid receptor with multiple ligand-binding domains.

Previously we isolated a new group of cDNA clones from human testis cDNA libraries which might code for new steroid receptors. The cDNA and predicted amino acid sequences of two of these receptors, named TR2-5 and TR2-7 receptors, were determined. We report here the nucleotide and deduced amino acid structures of two other receptors that we named TR2-9 and TR2-11 receptors. The calculated MW of TR2-5 receptor, TR2-7 receptor, TR2-9 receptor and TR2-11 receptor are 52,982, 20,528, 50,849 and 67,223 respectively, which match well with the apparent MW of in vitro translated products. The 26 amino acids involved in the formation of "Zn-fingers" are conserved. The ligand-binding domain of TR2-9 receptor is 16 amino acids shorter and has 3 different amino acids compared with TR2-5 receptor. The TR2-11 receptor has a ligand-binding domain which is longer and quite different compared with the other TR2 receptors. The multiple ligand-binding domains of TR2 receptor could be the products of different genes or may be due to RNA splicing errors. So far, we have failed to find binding activity with any known steroid hormone; this promotes the possibility that an unidentified steroid hormone may be involved.

Amino Acid Sequence↗
PubMed1989

Isolation and characterization of human TR3 receptor: a member of steroid receptor superfamily.

Complementary DNAs (cDNAs) encoding a member of steroid receptor super-family, named TR3 receptor, were isolated from a human prostate lambda gt11 cDNA library on the basis of homology of oligonucleotide probes to the DNA-binding domain common to members of the steroid receptor super-family. Expression of TR3 receptor cDNA produced a 64 kDa DNA-binding protein in a rabbit reticulocyte lysate. Nucleotide sequence analysis showed that TR3 receptor cDNA contains two regions of sequences which correspond to the DNA- and hormone-binding domains of members of the steroid receptor super-family. The amino acid sequences in the hormone-binding domain of the TR3 receptor shares about 20% homology with estrogen receptor and less than 15% homology with other known steroid receptors. The DNA-binding domain of the TR3 receptor has about 55% homology with all other known steroid receptors. TR3 receptor had 86% nucleotide and 91% amino acid sequence homology with mouse NUR/77, suggesting that TR3 receptor may be a human homologue of mouse NUR/77 gene product.

Amino Acid Sequence↗