Search PubMed⌕ Search

Biomedical subjects

H Chang

Publications and source records attributed to H Chang.

At least 37 records · Page 2Linked to original sources
PubMed2003

Suppurative salmonella thyroiditis in a patient with chronic lymphocytic leukemia.

We describe an 82-year-old man with undiagnosed chronic lymphocytic leukemia (CLL) who presented with acute swelling of the thyroid goiter. Subsequent thyroid aspirate and blood culture yielded group B Salmonella thyroid abscess with septicemia. Infectious complications are the major cause of morbidity and mortality in patients with CLL since most of them can be timely detected and few can arise from innocent-looking lesions.

Abscess↗
PubMed2003

Primary aleukemic myeloid leukemia cutis treated successfully with combination chemotherapy: report of a case and review of the literature.

Aleukemic myeloid leukemia cutis is extremely rare and is usually associated with early marrow relapse and poor treatment outcome. We report a 39-year-old man presenting with generalized cutaneous nodules. The initial diagnosis was cutaneous malignant lymphoma. New skin lesions and a nasopharyngeal mass developed during phototherapy. Biopsy of the cutaneous and nasopharyngeal lesions revealed monotonous blast cell infiltration. Cytochemical stain and immunophenotypic analysis of the fresh cell suspension made from another skin biopsy specimen identified that the neoplastic cells belonged to the monocytic lineage. A diagnosis of primary aleukemic leukemia cutis was established. The leukemic cells expressed CD56 but did not carry AML-1/ETO, CBFbeta/MYH11, or common MLL fusion transcripts. He received standard induction therapy for acute myeloid leukemia, followed by high-dose postremission chemotherapy and has been disease-free for more than 30 months. To the best of our knowledge, the current case has the longest disease-free survival among those reported.

Adult↗
PubMed2003

Anatomical relationship between arteries and veins in the paraumbilical region.

Veins in the paraumbilical region were investigated in eight fresh cadavers, in which radiopaque materials were injected into both the arterial and the venous systems, to determine their locational relationship to the arteries. Veins in the skin and subcutaneous tissue consisted of venae comitantes and non-venae comitantes. The main trunk of the non-venae comitantes was the superficial inferior epigastric vein, and it formed a polygonal venous network in the skin layer. A large communicating vein, which did not accompany an artery, connected the venous network to a vena comitans of a large paraumbilical arterial perforator. Venous blood that had perfused the dermis of the paraumbilical region had two kinds of pathways to a deep vein: through the superficial inferior epigastric vein to the femoral vein and through the vena comitans to the deep inferior epigastric vein.

Arteries↗
PubMed2002

The effect of storage temperatures on the in vitro properties of a polyanhydride implant containing gentamicin.

Septacin is a biodegradable sustained-release implant containing 20% (w/w) gentamicin sulfate. The matrix of the implant is a polyanhydride copolymer composed of erucic acid dimer (EAD) and sebacic acid (SA) in a one-to-one weight ratio. The effect of storage temperatures (-15 degrees C and 25 degrees C) on the stability of Septacin was evaluated with respect to gentamicin potency, copolymer molecular weight, and in vitro drug release. The drug in polymer matrix was stable for at least 12 months when stored at 25 degrees C, but the molecular weight of the copolymer declined rapidly at this temperature. At -15 degrees C, there was no change in the molecular weight of the copolymer. However, the placebo (copolymer without gentamicin) exhibited a significant drop in copolymer molecular weight at both temperatures. The drug release profiles showed no change for samples stored at -15 degrees C for the duration of this study, while the release of drug slowed down significantly for samples stored at 25 degrees C for longer than one month. A pronounced difference in the morphology of the -15 degrees C samples and the 25 degrees C samples was observed during the in vitro dissolution test; cracking of the -15 degrees C samples was evident, but the 25 degrees C samples remained intact.

Anhydrides↗
PubMed2001

Phosphatidic acid is the prominent product of endogenous neuronal nuclear lipid phosphorylation, an activity enhanced by sphingosine, linked to phospholipase C and associated with the nuclear envelope.

Using endogenous lipid substrates, assays of lipid phosphorylation indicated that neuronal nuclei had a considerable superiority in phosphatidic acid (PA) formation when compared with homogenates and other subfractions of cerebral cortex. This predominance of neuronal nuclear PA labelling was linked to a sizable pool of nuclear diacylglycerols that expanded significantly with incubation. PA was also the dominant product of neuronal nuclear lipid phosphorylation reactions. Nuclear envelope preparations and the parent neuronal nuclei showed specific rates of PA formation that were comparable, based upon membrane phospholipid contents. As well, using an exogenous diacylglycerol substrate, the distribution of diacylglycerol kinase activities closely followed phospholipid contents of subfractions derived from the neuronal nucleus during envelope preparation. This evidence suggested an association between diacylglycerol kinase and the neuronal nuclear envelope. Nuclear PA formation increased in the presence of sphingosine, while sphingosine decreased PA formation in other subfractions. Likely sphingosine exerted its effect on nuclear diacylglycerol kinase, as sphingosine did not elevate levels of nuclear diacylglycerols. Phosphoinositidase C was present in the nuclei and inhibitors of this enzyme did decrease PA formation, indicating diacylglycerols from inositides as substrates for nuclear diacylglycerol kinase. The nuclear envelope fraction had a considerably lower specific phosphoinositidase C activity than the parent nuclei, and showed an activation of PA formation by sphingosine, but a less efficient handling of the exogenous diacylglycerol substrate. It is possible that phosphoinositidase C and diacylglycerol kinase are closely situated within the neuronal nuclei, and a loss of the former activity may compromise the latter.

Animals↗
PubMed2001

Simple bone cyst of lamina of lumbar spine: a case report.

STUDY DESIGN: A case report and literature review. OBJECTIVE: To describe an extremely rare simple bone cyst involving the lamina of the lumbar spine. SUMMARY OF BACKGROUND DATA: Simple bone cysts involving the spine are very rare. Moreover, the authors are unaware of any published report of a simple bone cyst involving the lamina of the spine. METHODS: A cystic lesion, incidentally identified in a patient with lumbar disc herniation of L5-S1, located at the left lamina of L5, was surgically treated with complete resection of the involved lamina and discectomy of L5-S1. Medical records, imaging studies, histologic findings, and related literature are reviewed in this study. RESULTS: Histologic examination of a section of the cystic lesion showed a thin fibrous lining membrane of the cyst surrounded by well-vascularized new bone formation. This result is consistent with the findings of previously reported simple bone cysts in other sites of the body, including the spine. CONCLUSION: This study suggests that a simple bone cyst may be included in the differential diagnosis of a cystic lesion of the posterior elements, especially laminae, of the spine.

Adult↗
PubMed2001

Thermo-Raman studies on NaH(2)PO(4)-H(2)O for dehydration, condensation, and phase transformation.

Thermo-Raman spectroscopy was applied to study the thermal properties of NaH(2)PO(4)-2H(2)O from room temperature up to 600 degrees C. Raman spectra recorded at every degree of the temperature interval by monitoring the internal modes gave the microscopic picture of dehydration of NaH(2)PO(4)-2H(2)O, the condensation of NaH(2)PO(4), and the phase transformation of NaPO(3). The spectral variation observed could distinguish two steps of dehydration, resulting in the formation of NaH(2)PO(4)-H(2)O and NaH(2)PO(4) as compositional species from NaH(2)PO(4)-2H(2)O. The thermo-Raman intensity (TRI) and differential thermo-Raman intensity (DTRI) thermograms also showed two steps of dehydration in the temperature range from 42 to 52 degrees C and from 60 to 72 degrees C with a maximum rate at 48 and 68 degrees C, respectively. Furthermore, condensation resulted in sodium dihydrogen diphosphate (Na(2)H(2)P(2)O(7)) and sodium metaphosphate (NaPO(3)) in two steps at 212-224 and 260-360 degrees C, respectively. Clear evidence in the spectral variation representing two phase transformations of NaPO(3) at the temperature of 345 and 515 degrees C with three different polymorphs (phase III, phase II, and phase I of NaPO(3) in increasing order of temperature) was also observed. The thermal methods thermogravimetry, differential thermogravimetry, differential thermal analysis, and differential scanning calorimetry also supported the results but could not give a clear idea due to the lack of direct structural information.

Journal Article↗
PubMed2001

Quantitative analysis of transforming growth factor-beta 1 in ligamentum flavum of lumbar spinal stenosis and disc herniation.

STUDY DESIGN: The concentration of transforming growth factor-beta 1 (TGF-beta1) was examined in the ligamentum flavum of lumbar spinal stenosis and disc herniation. OBJECTIVE: To investigate the role of TGF-beta1 on hypertrophy of the ligamentum flavum in lumbar spinal stenosis compared with that of lumbar disc herniation. SUMMARY OF BACKGROUND DATA: The hypertrophy of the ligamentum flavum is known to be related to degenerative changes that are secondary to the aging process or mechanical instability. However, there has been no study to investigate the effect of biochemical factors, such as growth factors, associated with hypertrophy of the ligamentum flavum. METHODS: The concentrations of TGF-beta1 were analyzed in the surgically obtained ligamentum flavum specimens from lumbar spinal stenosis (n = 10; mean age 62.8 years) and disc herniation (n = 10; mean age 35.6 years) by enzyme-linked immunosorbent assay. The localization of TGF-beta1 within the ligamentum flavum was determined using immunohistochemical study. The thickness of the ligamentum flavum was measured with axial T1-weighted magnetic resonance imaging. The biochemical and radiologic results were compared for these two conditions. RESULTS: The mean concentration of TGF-beta1 was 123.78 pg/100 microg protein (range 11-374 pg/100 microg protein) in lumbar spinal stenosis and 38.56 pg/100 microg protein (range 0-155 pg/100 microg protein) in lumbar disc herniation; the difference between lumbar spinal stenosis and disc herniation was statistically significant (P = 0.029). The mean thickness of the ligamentum flavum was 4.44 mm (range 3.4-5.4 mm) in lumbar spinal stenosis and 2.44 mm (range 1.8-4.0 mm) in lumbar disc herniation; the difference between lumbar spinal stenosis and disc herniation was statistically significant (P = 0.001). On immunohistochemical study TGF-beta1 was positively stained on the fibroblasts within the ligamentum flavum specimens. CONCLUSION: The current results suggest that higher expression of TGF-beta1 by fibroblasts might be related to the development of hypertrophy of the ligamentum flavum in lumbar spinal stenosis.

Aged↗
PubMed2001

PicSNP: a browsable catalog of nonsynonymous single nucleotide polymorphisms in the human genome.

Recent progress in identification and mapping of single nucleotide polymorphisms (SNPs) in the human genome generates an unprecedented opportunity to explore cause-effect relationships between genetic variations and susceptibility to common diseases. For this purpose, one promising strategy would be to select a set of SNPs that potentially alter the function of proteins involved in the pathogenesis of the diseases and compare their frequencies in the affected individuals and the healthy population. In this respect, SNPs that change amino acid sequences (nonsynonymous SNPs; nsSNPs) are of particular interest, since they are more likely to affect protein functions. In this study, we have constructed a catalog of nsSNPs (PicSNP), whose unique features are (i) nsSNPs are classified according to the functions of the affected genes and are searchable under the guidance of hierarchical lists of protein functions and (ii) nsSNPs that lead to amino acid changes in the known functional sites and domains of proteins are highlighted. Out of 1,190,295 SNPs extracted from public database, we identified 3793 nsSNPs and classified them in 1247 categories of protein functions. 495 sites and domains annotated in the Swiss-Prot database were found to include nsSNPs, including 2 nsSNPs in disulfide-binding sites and 38 nsSNPs in transmembrane regions. PicSNP is available via the World Wide Web (http://picsnp.org) and would support research questing for SNPs involved in common diseases.

Databases, Factual↗
PubMed2001

Studying TGF-beta superfamily signaling by knockouts and knockins.

The transforming growth factor beta (TGF-beta) superfamily has profound effects on many aspects of animal development. In the last decade, our laboratory and others have performed in vivo functional studies on multiple components of the TGF-beta superfamily signal transduction pathway, including upstream ligands, transmembrane receptors, receptor-associated proteins and downstream Smad proteins. We have taken gene knockout approaches to generate null alleles of the genes of interest, as well as a gene knockin approach to replace the mature region of one TGF-beta superfamily ligand with another. We found that activin betaB, expressed in the spatiotemporal pattern of activin betaA, can function as a hypomorphic allele of activin betaA and rescue the craniofacial defects and neonatal lethal phenotype of activin betaA-deficient mice. With the knockout approach, we have shown that the expression pattern of a component in the TGF-beta superfamily signal transduction cascade does not necessarily predict its in vivo function. Two liver-specific activins, activin betaC and activin betaE are dispensable for liver development, regeneration and function, whereas ubiquitously expressed Smad5 has specific roles in the development of multiple embryonic and extraembryonic tissues.

Activins↗
PubMed2001

Expression of Fas ligand and apoptosis of disc cells in herniated lumbar disc tissue.

STUDY DESIGN: An examination of surgically obtained herniated lumbar disc tissues performed by using immunohistochemical staining and the DNA nick end labeling method. OBJECTIVE: To investigate the cell type that expresses Fas ligand (FasL) and any evidence of apoptosis of the disc cells in herniated lumbar disc tissues. SUMMARY OF BACKGROUND DATA: The Fas/FasL system is involved in delivering a death signal that rapidly commits the cells to apoptosis. In the authors' previous study, the expression of Fas on disc cells was identified in herniated lumbar disc tissue. METHODS: Twenty-three herniated lumbar disc tissues (contained disc, n = 9; noncontained disc, n = 14) were examined to investigate the cell type that expresses FasL and any evidence of apoptosis of the disc cells by using immunohistochemical staining and the DNA nick end labeling method, respectively. The percentage of FasL-positive disc cells was calculated and compared with clinical and radiologic data. RESULTS: FasL was expressed in the cytoplasm of the disc cells, and nuclear DNA fragmentation in a few disc cells was identified. A higher degree of FasL expression in disc cells was found in noncontained discs than in contained discs (P < 0.05). The percentage of FasL-positive disc cells significantly increased with the patient's age (P < 0.05), but not with the degree of disc degeneration (P > 0.05). CONCLUSION: The current results indicate that disc cells, after herniation, undergo apoptotic cell death via autocrine or paracrine FasL mechanisms by the disc cells themselves.

Adult↗
PubMed2001

Facet tropism: a comparison between far lateral and posterolateral lumbar disc herniations.

STUDY DESIGN: An assessment of the difference in the degree of facet tropism and disc degeneration between far lateral and posterolateral lumbar disc herniations. OBJECTIVE: To investigate the effect of the difference in the degree of the facet tropism and disc degeneration with respect to the development of far lateral lumbar disc herniation and posterolateral lumbar disc herniation, and to compare the effect between the two types of herniations. SUMMARY OF BACKGROUND DATA: The effect of facet tropism on the development of posterolateral lumbar disc herniation has been investigated previously, but there has been no study on far lateral lumbar disc herniation. METHODS: Thirty-eight lumbar disc herniations (far lateral, n = 19; posterolateral, n = 19) were included this study. The degree of facet tropism and disc degeneration was measured at the herniated disc level by using magnetic resonance imaging. The results were compared to show any differences between the two types of lumbar disc herniations. RESULTS: There were significant differences in the degree of facet tropism (24.74 vs. 14.26, P = 0.004) and disc degeneration (23.92 vs. 15.08, P = 0.005) between the far lateral and posterolateral lumbar disc herniations. There was no significant correlation between the degree of facet tropism and the degree of disc degeneration in far lateral lumbar disc herniation (r = -0.369, P = 0.120). CONCLUSION: This results suggest that the differences in the degree of facet tropism and disc degeneration might be considered a key factor in distinguishing the development of far lateral lumbar disc herniation from that of posterolateral lumbar disc herniation.

Adult↗
PubMed2001

Expression of Fas receptor on disc cells in herniated lumbar disc tissue.

STUDY DESIGN: The expression of Fas receptor, an apoptosis-related protein, on disc cells was examined in surgically obtained disc specimens. OBJECTIVE: To assess the fate of disc cells in herniated disc tissue and the difference in the degree of expression of the Fas receptor between contained and noncontained discs. SUMMARY OF BACKGROUND DATA: Little is known about the fate of disc cells after herniation. METHODS: Twenty-three herniated lumbar disc specimens were classified into contained discs (protrusion or subligamentous extrusion; n = 9) and noncontained discs (transligamentous extrusion or sequestration; n = 14). All specimens were stained using the avidin-biotin-peroxidase complex method. The percentage of disc cells positive for Fas receptor was calculated and compared with clinical and radiologic data. RESULTS: There was a significant difference in the percentage of Fas-positive disc cells between the contained and noncontained discs (8.44 vs.- 14.29;P = 0.044). The percentage of Fas-positive disc cells correlated significantly with the patient's age (r = 0.455, P = 0.029), but not with the degree of disc degeneration on magnetic resonance imaging (r = 0.252, P = 0.214). CONCLUSION: This is the first study to identify the expression of Fas receptor on disc cells in herniated disc tissue. The results show that the disc cells after herniation may undergo Fas-mediated apoptosis and that the degree of expression of Fas receptor differs depending on the type of herniation.

Adolescent↗
PubMed2001

Identification of a DNA encapsidation sequence for human polyomavirus pseudovirion formation.

Human polyomavirus is a naked capsid virus containing a closed circular double-stranded DNA genome. The mechanism of DNA encapsidation for the viral progeny formation is not fully understood. In this study, DNA encapsidation domain of the major capsid protein, VP1, of the human polyomavirus JCV was investigated. When the first 12 amino acids were deleted, the E. coli expressed VP1 (Delta N12VP1) failed to encapsidate the host DNA although the integrity of the capsid-like structure was maintained. In addition, capsid-like particles of Delta N12VP1 did not package exogenous DNA in vitro, which is in contrast to that of the full-length VP1 protein. These findings suggest that the N-terminal of the first 12 amino acids of VP1 were responsible for DNA encapsidation. The importance of amino acids in the DNA encapsidation domain was determined further using site-directed mutagenesis. All of the positively charged amino acids at the N-terminal region of VP1 were essential for DNA encapsidation. The results indicate that the N-terminal region of the human polyomavirus major capsid protein VP1 may be involved in viral genome encapsidation during progeny maturation.

Amino Acid Sequence↗
PubMed2001

Embryonic stem cell-derived neurogenesis. Retinoic acid induction and lineage selection of neuronal cells.

Embryonic stem (ES) cells are able to differentiate in vitro into endodermal, mesodermal, and ectodermal cell types. However. the spontaneous development of neuronal cells from ES cells is rather limited. Therefore, specific protocols to increase the differentiation of neuronal cells have been established, such as retinoic acid (RA) induction and lineage selection of neuronal cells. High concentrations of RA resulted in efficient neuronal differentiation paralleled by the expression of tissue-specific genes, proteins, ion channels, and receptors in a developmentally controlled manner. Because the developmental pattern and survival capacity of RA-induced neuronal cells were limited, specific differentiation protocols by lineage selection of neuronal cells have been established using growth and extracellular matrix factors. After formation of cells of the three primary germ layers, mesodermal differentiation was inhibited by serum depletion, and neural precursor cells were generated by addition of basic fibroblast growth factor, followed by differentiation induction by neuronal differentiation factors. Further application of survival-promoting factors such as neurotrophic factors and cytokines at terminal stages resulted in a significant increase, survival, and maintenance of dopaminergic neurons. In the future, these cellular systems will be applicable: (1) for studying commitment and neuronal specification in vitro, (2) as pharmacological assays for drug screening, and (3) for the selective isolation of differentiated neuronal cells which may be used as a source for cell and tissue grafts.

Animals↗
PubMed2001

Traumatic posterior atlantooccipital dislocation with Jefferson fracture and fracture-dislocation of C6-C7: a case report with survival.

Atlantooccipital dislocation (AOD) is a rare and usually fatal injury. In the current study, the authors reported an extremely rare case of posterior AOD with Jefferson fracture and fracture-dislocation of C6-C7. The patient survived the injury and had only incomplete quadriplegia below the C7 segment with anterior cord syndrome. He was successfully managed with in situ occipitocervical fusion using the Cotrel-Dubousset rod system, corpectomy of C6, and anterior interbody fusion of C5-C7 with plating. To our knowledge, this is the first report of posterior AOD with two other non-contiguous cervical spine injuries. A high index of suspicion and careful examination of the upper cervical spine should be considered as the key to the diagnosis of AOD in cases that involve multiple or lower cervical spine injuries.

Adult↗
PubMed2001

Smad5 is required for mouse primordial germ cell development.

Smad5, together with Smad1 and Smad8, have been implicated as downstream signal mediators for several bone morphogenetic proteins (BMPs). Recent studies have shown that primordial germ cells (PGCs) are absent or greatly reduced in Bmp4 or Bmp8b mutant mice. To define the role of Smad5 in PGC development, we examined PGC number in Smad5 mutant mice by Oct4 whole-mount in situ hybridization and alkaline phosphatase staining. We found ectopic PGC-like cells in the amnion of some Smad5 mutant mice, however, the total number of PGCs was greatly reduced or completely absent in Smad5 mutant embryos, similar to Bmp4 or Bmp8b mutant embryos. Therefore, Smad5 is an important factor involved in PGC generation and localization.

Alkaline Phosphatase↗