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Biomedical subjects

C C Chang

Publications and source records attributed to C C Chang.

At least 127 records · Page 7Linked to original sources
PubMed2000

Effect of electromagnetic field exposure on chemically induced differentiation of friend erythroleukemia cells.

Whether exposure of humans to extremely low frequency electromagnetic fields (ELF-EMF) can cause cancer is controversial and therefore needs further research. We used a Friend erythroleukemia cell line that can be chemically induced to differentiate to determine whether ELF-EMF could alter proliferation and differentiation in these cells in a manner similar to that of a chemical tumor promoter. Exposure of this cell line to 60 Hz ELF-EMF resulted in a dose dependent inhibition of differentiation, with maximal inhibition peaking at 40% and 40 mG (4 microT). ELF-EMF at 10 mG (1.0 microT) and 25 mG (2.5 microT) inhibited differentiation at 0 and 20%, respectively. ELF-EMF at 1.0 (100) and 10.0 G (1,000 microT) stimulated cell proliferation 50% above the sham-treated cells. The activity of telomerase, a marker of undifferentiated cells, decreased 100[times] when the cells were induced to differentiate under sham conditions, but when the cells were exposed to 0.5 G (50 microT) there was only a 10[times] decrease. In summary, ELF-EMF can partially block the differentiation of Friend erythroleukemia cells, and this results in a larger population of cells remaining in the undifferentiated, proliferative state, which is similar to the published results of Friend erythroleukemia cells treated with chemical-tumor promoters.

Cell Differentiation↗
PubMed2000

Immunophenotypic profile of myeloid cells in granulocytic sarcoma by immunohistochemistry. Correlation with blast differentiation in bone marrow.

The present study was designed to evaluate the lineage differentiation (particularly monocytic differentiation) of immature myeloid cells in granulocytic sarcoma (GS) by immunohistochemistry and correlate the results with lineage differentiation of blasts in the bone marrow and to determine the degree of maturation of the infiltrating myeloid cells in GS by immunohistochemistry using CD34 and HLA-DR. Immunohistochemical stains were performed on paraffin-embedded tissue from 17 GS lesions with lineage-associated markers: myeloperoxidase, CD68 (KP1), CD68 (PG-Ml), glycophorin A, factor VIII, and CD56; and with markers for blasts and immature myeloid cells: CD34 and HLA-DR. Our results show that positive staining with PG-M1, but not KP1, suggests monocytic differentiation of myeloid cells in GS and correlates with the monocytic differentiation of blasts in the bone marrow. Expression of CD56 is frequent in GS, especially when the marrow blasts have monocytic differentiation, and should not be interpreted as a primary natural-killer cell process. The immature myeloid cells in GS are frequently HLA-DR positive. However, CD34 positivity of the immature myeloid cells is relatively uncommon, except in cases with underlying myelodysplastic syndrome or chronic myelogenous leukemia.

Adolescent↗
PubMed2000

Expression of c-Myc and p53 correlates with clinical outcome in diffuse large B-cell lymphomas.

We performed a retrospective immunohistochemical study of the relationships between clinical manifestations and outcomes of diffuse large B-cell lymphoma (DLBCL) and expression of oncogenic proteins in 21 cases of DLBCL at various clinical stages. Cases of nodal origin expressed p53 more often and presented with high clinical stage more frequently than those of extranodal origin. Expression of c-Myc or p53, but not Bcl-6, Bcl-2, or Bcl-1, showed a statistically significant positive correlation with high clinical stage at presentation and with high or high-intermediate risk. Coexpression of c-Myc and p53 occurred in 7 of 12 patients with high clinical stage but was absent in patients with low clinical stage; coexpression was more frequent in patients with high or high-intermediate risk than in patients with low or low-intermediate risk. Four patients with this coexpression pattern demonstrated an unusually aggressive clinical course (median survival, 7 months). Coexpression of c-Myc and p53 seems to be a better indicator than the MIB1 proliferative index for identification of a cohort of aggressive disease in patients with DLBCL.

Adult↗
PubMed2000

Expression and high-level secretion of Trichoderma reesei endoglucanase I in Yarrowia lipolytica.

The endoglucanase I (EGI) from fungus Trichoderma reesei was cloned, expressed, and secreted from Yarrowia lipolytica using the XPR2 promoter. The signal sequence of EGI transferred from T. reesei was efficiently processed in the Y. lipolytica secretory pathway and directed the secretion of active EGI into the culture medium. However, the recombinant EGI produced from YLCSIn strain was hyperglycosylated and significantly larger than the native enzyme produced by the parent strain. The expression of EGI using XPR2 preproregion has caused secretion of modified proteins that still retained cellulase activity. This resulted from imprecise processing of the N-terminus of recombinant protein. While the batch culture produced 5 mg EGI/L from YLCSIn strain, the EGI yield was increased approx 20-fold when the fed-batch fermentation process strategy in combination with the high-cell density cultivation technique was employed. These results showed that the Y. lipolytica is a useful host organism for production of a large amount of large size heterologous proteins, especially when used in combination with high-cell density and fed-batch culture techniques.

Cellulase↗
PubMed2000

Decreased CD10-positive mature granulocytes in bone marrow from patients with myelodysplastic syndrome.

OBJECTIVE: We retrospectively examined the maturation of the granulocytic cell lineage in bone marrow specimens from patients with myelodysplastic syndrome (MDS) by flow cytometry using both light scatter and surface marker characteristics, including CD10 and myeloid lineage-associated antigens. PATIENTS: The 7 MDS cases we studied included 2 patients with refractory anemia (RA), 3 with RA with ringed sideroblasts, 1 with RA with excess of blasts, and 1 unclassified case. Another 7 patients matched for age and sex who received bone marrow aspirates for lymphoma staging (all negative for lymphoma involvement or any other hematologic abnormalities) were selected as the control group. RESULTS: The percentage of CD10(+) mature granulocytes was significantly lower in patients with MDS than in control patients. Additionally, all patients with MDS had less than 50% CD10(+) cells in the granulocytic lineage. In contrast, only 1 of the 7 control patients had less than 50% CD10(+) cells (P <.01). CONCLUSIONS: These results suggest that flow cytometry might be a useful adjunct in the assessment of patients with suspected MDS. Further studies to correlate CD10(+) mature granulocytes from MDS cases with other benign hematologic disorders are indicated to confirm our evaluation.

Aged↗
PubMed2000

Serologic and molecular evidence of Ehrlichia spp. in coyotes in California.

In order to determine the role of coyotes in the epidemiology of granulocytic and monocytic ehrlichial agents in California (USA), we tested 149 serum samples for antibodies against Ehrlichia equi, E. risticii, and E. canis, using an indirect immunofluorescent antibody test. Polymerase chain reaction (PCR) assay was used to survey for the presence of members of the E. phagocytophila genogroup, E. risticii and E. canis in blood samples of 95 coyotes. Sixty-eight (46%) samples were seropositive for E. equi, two (1%) for E. risticii and none of the samples had antibodies reactive to E. canis. Two and one coyote were positive for E. risticii and members of the E. phagocytophila genogroup by PCR assay, respectively. In contrast, the 95 samples were negative for E. canis by PCR. Ninety-five percent of the 68 E. equi seropositive coyotes and the one coyote PCR positive for members of the E. phagocytophila genogroup originated from a coastal area. However, the two E. risticii seropositive coyotes and the two coyotes PCR positive for E. risticii were from northern California. Sequence analysis of the three amplified PCR products revealed the agent to be similar in two coyotes to the sequences of E. risticii from horses originating from northern California and identical in one coyote to the agent of human granulocytic ehrlichiosis and E. equi from California. Thus, coyotes are exposed to granulocytic ehrlichiae and E. risticii and may play a role in the epidemiology of these ehrlichial agents in California.

Age Factors↗
PubMed2000

Precipitate delivery and postpartum hemorrhage after term induction with 200 micrograms misoprostol.

Misoprostol has been widely applied in early pregnancy termination and term pregnancy induction. However, the upper dosage limit of misoprostol through vaginal route has not been firmly established. Most popular dosages of vaginal misoprostol recommended are 25, 50 or 100 micrograms. There are no reports on the dangers of high-dosage misoprostol 200 micrograms as used in term labor induction. We present a primiparaous woman who was administered 200 micrograms misoprostol vaginally for term labor induction. The following precipitate delivery resulted in multiple lacerations of the isthmus, cervix and vagina, postpartum hemorrhage and disseminated intravascular coagulopathy. Inevitably, a hysterectomy was performed. A postsurgical check of the uterus confirmed lacerations of the isthmus and internal cervix. This rare complication suggests the possible dangers of vaginal misoprostol doses as high as 200 micrograms for term induction of labor at term.

Adult↗
PubMed2000

Effects of radiotherapy for nasopharyngeal carcinoma on the paranasal sinuses: study based on computed tomography scanning.

OBJECTIVE: The purpose of this study was to determine if radiotherapy for nasopharyngeal carcinoma causes mucosal disease of the paranasal sinuses. DESIGN: This study was a retrospective study. SETTING: This study was conducted at a tertiary care centre. METHOD: A series of 69 newly diagnosed patients, without pre-existing sinus disease, who were treated with high-dose radiotherapy participated. MAIN OUTCOME MEASURES: The prevalence, severity, and time course of mucosal abnormalities were analyzed, as judged by consecutive computed tomographies (CTs). RESULTS: The CT study revealed that 58.8% of the postirradiation scans had mucosal disease of the sinuses. The maxillary sinus had the highest prevalence (42.3%) without statistical significance (p = .10). The difference by McNemar test for two follow-up scans was not significant (p = .48) and by Kappa test was significant (p = .04). The relationship between the prevalence and the time course post radiotherapy revealed that it remained a high prevalence until after the 4-year follow-up scans. CONCLUSIONS: The results of this study confirm that chronic sinus disease is a common late complication of radiotherapy and it persists for years. Thus, aggressive treatment is indicated.

Adolescent↗
PubMed2000

Artificial insemination. Role of endometrial thickness and pattern, of vascular impedance of the spiral and uterine arteries, and of the dominant follicle.

OBJECTIVE: To assess the roles of endometrial thickness and pattern, as well as vascular impedance of the spiral and uterine arteries and dominant follicle in predicting the pregnancy rate in women receiving controlled ovarian hyperstimulation (COH) following by intrauterine insemination (IUI). STUDY DESIGN: All idiopathically infertile couples who accepted COH + IUI for the first time were prospectively included. The COH agents included clomiphene citrate and human menopausal gonadotropins. Endometrial thickness and pattern (trilaminar, nontrilaminar) and vascular impedance (pulsatility index [PI], resistance index [RI]) of the spiral and uterine arteries and ovarian dominant follicle were measured on the day of IUI. Analyses were made of the influences on pregnancy outcomes by endometrial thickness and pattern as well as Doppler surveys of the spiral and uterine arteries and dominant follicle. RESULTS: A total of 110 couples with 110 cycles were enrolled, and there were 16 resulting pregnancy cycles. Trilaminar endometrium appeared in 87.5% and 57.4% of pregnant and nonpregnant women (P = .022), respectively. The pregnancy rates in trilaminar and nontrilaminar groups were 17.9% and 6.3%, respectively (P = .022). Endometrial thickness and PI/RI values for the spiral artery and uterine arteries and dominant follicle in pregnant women (12.1 +/- 2.6; 1.28 +/- 0.33/0.68 +/- 0.12; 2.67 +/- 0.51/0.72 +/- 0.32; 0.71 +/- 0.19/0.54 +/- 0.06 mm, respectively) were not statistically different from those for nonpregnant women (11.0 +/- 2.9; 1.46 +/- 0.49/0.71 +/- 0.21; 2.81 +/- 0.65/0.88 +/- 0.34; 0.74 +/- 0.24/0.55 +/- 0.09, respectively). CONCLUSION: A trilaminar endometrium on the day of IUI provides a favorable prediction of pregnancy. Endometrial thickness and Doppler surveys of the spiral and uterine arteries and dominant follicle do not have useful predictive value in COH + IUI.

Adult↗
PubMed2000

Factors affecting the outcome of surgical treatment of acromegaly.

PURPOSE: To assess the results of and factors associated with the outcome of surgery for acromegaly. METHODS: We retrospectively examined the medical records of acromegalic patients who underwent trans-sphenoidal adenomectomy at our hospital during the period of January 1991 through August 1997. Preoperative evaluations included measurement of basal serum growth hormone (GH), insulin-like growth factor-I (IGF-I), prolactin (PRL), GH response to oral glucose, and GH and PRL response to bromocriptine, as well as pituitary magnetic resonance (MR) imaging. Postoperative evaluations included measurement of basal serum GH and IGF-I concentrations, and pituitary MR imaging. RESULTS: Thirty patients (14 men) with a mean age of 38 years were included. The mean follow-up period was 50 months (range, 15-90 mo). Ten of the 30 patients (33%) had early postoperative (1 mo after surgery) GH levels of less than 5 ng/mL. Twenty patients (67%) had final postoperative (last follow-up, 15-90 mo after surgery) GH levels of less than 5 ng/mL. Preoperative GH levels were positively correlated with early postoperative GH levels (r = 0.458, p = 0.011) and final postoperative GH levels (r = 0.479, p = 0.007). Early postoperative GH levels were also positively correlated with final postoperative GH levels (r = 0.595, p = 0.001). Tumor grade and stage were not significantly correlated with early or final postoperative GH levels. Thirteen of 21 patients (62%) who had postoperative MR imaging follow-up had residual tumor. There was no surgical mortality. CONCLUSIONS: These results highlight that acromegaly is not easily treated with surgery alone. The preoperative GH level was associated with the surgical outcome.

Acromegaly↗
PubMed2000

Sperm cryopreservation with empty human or mouse zona pellucidae. A comparison.

OBJECTIVE: To compare empty zona pellucidae (ZP) and human of mouse oocytes for sperm cryopreservation. STUDY DESIGN: ZP was prepared by evacuating the cytoplasm of human or mouse oocytes. The evacuated ZP were injected with spermatozoa from patients with severe oligoasthenozoospermia from normally fertile men. After a freezing-thawing procedure, the spermatozoa were aspirated outside the ZP. According to the different origins of ZP and sperm, the spermatozoa number per ZP, motile sperm number before freezing and after thawing, lost sperm number per ZP after freezing and sperm recovery rate were compared. RESULTS: Spermatozoa number, motile sperm number before freezing and after thawing, lost sperm number per ZP and sperm recovery rate in all groups were comparable. The total mean motile sperm number before freezing and after thawing, mean lost sperm number after thawing and sperm recovery rate were 15.1%, 12%, 1.6% and 80%, respectively. CONCLUSION: ZP is an ideal vehicle for cryopreservation of sperm collected from patients with severe oligoasthenozoospermia. There were no differences between human and mouse ZP for sperm storage.

Animals↗
PubMed2000

Canal-wall-down tympanoplasty with mastoidectomy for advanced cholesteatoma.

OBJECTIVE: The objective of this study was to review 8.5 years of the senior author's experience with canal-wall-down mastoid surgery for extensive cholesteatoma with high-grade atelectasis and severely destructed ossicles. DESIGN: A retrospective review was conducted. SETTING: The setting was a tertiary care medical centre. METHODS: Available records consulted included 104 canal-wall-down mastoidectomy for advanced-stage cholesteatomas between July 1984 and December 1992. MAIN OUTCOME MEASURES: Recurrence, hearing results, and dry ear rate were analyzed. RESULTS: The recurrence rate was 4 of 104 (3.8%), and 9.6% of subjects suffered from recurrent otorrhea. Thirty-seven of 104 (35.6%) achieved the closure of air-bone gap within 20 dB. The availability of stapes suprastructure influenced the postoperative hearing level significantly (p < .001). CONCLUSION: Even in treating advanced cholesteatoma, canal-wall-down mastoidectomy provides a low recurrence rate, establishes a high dry ear rate, and preserves adequate hearing when the stapes suprastructure is available for reconstruction.

Adolescent↗
PubMed1999

Human acyl-CoA:cholesterol acyltransferase-1 is a homotetrameric enzyme in intact cells and in vitro.

Acyl-CoA:cholesterol acyltransferase (ACAT) is a key enzyme in cellular cholesterol homeostasis and in atherosclerosis. ACAT-1 may function as an allosteric enzyme. We took a multifaceted approach to investigate the subunit composition of ACAT-1. When ACAT-1 with two different tags were co-expressed in the same Chinese hamster ovary cells, antibody specific to one tag caused co-immunoprecipitation of both types of ACAT-1 proteins. Radioimmunoprecipitations of cells expressing the untagged ACAT-1 or the 6-histidine-tagged ACAT-1 yielded a single radiolabeled band of predicted size on SDS-polyacrylamide gel electrophoresis. These results show that ACAT-1 exists as homo-oligomers in intact Chinese hamster ovary cells. We solubilized HisACAT-1 with the detergent deoxycholate or CHAPS (3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulfonic acid), performed gel filtration chromatography and sucrose density gradient centrifugations in H(2)O and D(2)O, and determined the Stokes radii and sedimentation coefficients of the HisACAT1-detergent complexes. The estimated molecular mass of HisACAT-1 is 263 kDa, which is 4 times that of the HisACAT-1 monomer (69 kDa). Finally, cross-linking experiments in intact cells and in vitro show that the increase in cross-linker concentrations causes an increase in size of the HisACAT-1-positive signals, forming material(s) 4 times the size of the monomer, supporting the conclusion that ACAT-1 is a homotetrameric enzyme.

Animals↗
PubMed1999

High susceptibility of a human breast epithelial cell type with stem cell characteristics to telomerase activation and immortalization.

We have recently characterized two types of normal human breast epithelial cells (HBECs) from reduction mammoplasty. Type I cells express estrogen receptor, luminal epithelial cell markers, and stem cell characteristics (i.e., the ability to differentiate into other cell types and to form budding/ductal structures on Matrigel), whereas Type II cells show basal epithelial cell phenotypes. In this study, we have examined whether Type I HBECs are more susceptible to telomerase activation and immortalization after transfection with SV40 large T-antigen. The results show that both types of cells acquire extended life span [(EL); i.e., bypassing senescence] at a comparable frequency. However, they differ significantly in the ability to become immortal in continuous culture, ie., 11 of 11 Type I EL clones became immortal compared with 1 of 10 Type II EL clones. Both parental Type I and Type II cells as well as their transformed EL clones at early passages [approximately 30 cumulative population doubling level (cpdl)] showed a low level of telomerase activity as measured by the telomeric repeat amplification protocol assay. For all 11 of the Type I EL clones and the single Type II EL clone that became immortal, telomerase activities were invariably activated at middle passages (approximately 60 cpdl) or late passages (approximately 100 cpdl). For the four Type II EL clones randomly selected from the nine Type II clones that did not become immortal, the telomerase activities were found to be further diminished at mid-passage, before the end of the life span. Thus, normal HBECs do have a low level of telomerase activity, and Type I HBECs with stem cell characteristics are more susceptible to telomerase activation and immortalization, a basis on which they may be major target cells for breast carcinogenesis.

Breast↗
PubMed1999

PEX12 interacts with PEX5 and PEX10 and acts downstream of receptor docking in peroxisomal matrix protein import.

Peroxisomal matrix protein import requires PEX12, an integral peroxisomal membrane protein with a zinc ring domain at its carboxy terminus. Mutations in human PEX12 result in Zellweger syndrome, a lethal neurological disorder, and implicate the zinc ring domain in PEX12 function. Using two-hybrid studies, blot overlay assays, and coimmunoprecipitation experiments, we observed that the zinc-binding domain of PEX12 binds both PEX5, the PTS1 receptor, and PEX10, another integral peroxisomal membrane protein required for peroxisomal matrix protein import. Furthermore, we identified a patient with a missense mutation in the PEX12 zinc-binding domain, S320F, and observed that this mutation reduces the binding of PEX12 to PEX5 and PEX10. Overexpression of either PEX5 or PEX10 can suppress this PEX12 mutation, providing genetic evidence that these interactions are biologically relevant. PEX5 is a predominantly cytoplasmic protein and previous PEX5-binding proteins have been implicated in docking PEX5 to the peroxisome surface. However, we find that loss of PEX12 or PEX10 does not reduce the association of PEX5 with peroxisomes, demonstrating that these peroxins are not required for receptor docking. These and other results lead us to propose that PEX12 and PEX10 play direct roles in peroxisomal matrix protein import downstream of the receptor docking event.

Alleles↗
PubMed1999

Management of patients with normal-pressure hydrocephalus by using lumboperitoneal shunt system with the Codman Hakim programmable valve.

Thirty-two patients with normal-pressure hydrocephalus were managed using the lumboperitoneal (LP) shunt system in which the Codman Hakim programmable valve was utilized. The initial opening pressure was set at 100 mm H(2)O in three cases, 80 mm H(2)O in two, 70 mm H(2)O in three cases, 50 mm H(2)O in 23, and 30 mm H(2)O in one case (mean pressure 57.8 mm H(2)O). In 12 patients the valve pressure required reprogramming. The final valve pressure was 30 mm H(2)O in four cases, 50 mm H(2)O in 19, 70 mm H(2)O in three, 80 mm H(2)O in one, 100 mm H(2)O in two, 130 mm H(2)O in one, 140 mm H(2)O in one, and 170 mm H(2)O in one case (mean 62.5 mm H(2)O). Lumboperitoneal shuntography was performed in five patients by injection of contrast medium into the prechamber. In two patients a shunt obstruction developed between the valve and the lumbar catheter. Complications occurred in eight patients. Low-pressure symptoms such as headache and vomiting were observed in four patients but disappeared after increasing the valve pressure. One patient, whose shunt pressure was set at 50 mm H(2)O developed a slight asymptomatic subdural effusion, which resolved after increasing the valve pressure to 100 mm H(2)O. Convulsions developed in two aged patients but were easily controlled with anticonvulsant medication. Surgery-related wound infection was observed in one patient. The major advantage in the use of this valve is the ability to modify the pressure noninvasively. Another important advantage of the LP shunt system in which this valve is incorporated is the lower pressure of 30 mm H(2)O that can improve symptoms caused by underdrainage of cerebrospinal fluid.

Journal Article↗
PubMed1999

Response of cerebral blood flow and cerebrovascular reactivity to acetazolamide in patients with dementia and idiopathic normal-pressure hydrocephalus.

The responses of cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) to administration of acetazolamide were investigated in 16 patients with dementia and ventriculomegaly to clarify the cerebral hemodynamics in patients with idiopathic normal-pressure hydrocephalus (NPH). The mean CBF velocity in the whole brain was measured by the Patlak plot method by using technetium-99m hexamethylpropyleneamine oxime single-photon emission computerized tomography. The CVR values were obtained from the response to administration of 500 mg of acetazolamide and calculated as the percentage of change from the baseline mean CBF value. The mean CBF value was significantly reduced (p < 0.01) in six patients with (35.2 +/- 5 ml/100 g/minute) and 10 patients without (33.5 +/- 2.8 ml/100 g/minute) NPH compared with the age-matched normal controls (40.8 +/- 3.2 ml/100 g/minute), showing no significant difference. The CVR was significantly impaired in patients with NPH (0.8 +/- 1.7%; p < 0.001), whereas in patients without NPH preserved CVR (11.3 +/- 3%) was demonstrated compared with the normal controls (14.7 +/- 1.1%). In patients with NPH a significantly lower CVR (p < 0.001) was shown than in those without NPH. The CVR significantly increased (p < 0.001) after placement of a shunt in patients with NPH. Reductions in both CBF and CVR may be diagnostic indicators of NPH in patients with dementia in whom ventriculomegaly is present. In patients with dementia and idiopathic NPH both reduced CBF and extremely impaired CVR are shown. The results of the present study suggest that ischemia due to the process of NPH is responsible for the reduction of CBF and manifestation of symptoms in patients with idiopathic NPH.

Journal Article↗