Biomedical subjects

C H Chang

Publications and source records attributed to C H Chang.

At least 469 records · Page 26Linked to original sources

PubMed1990

The treatment of medulloblastoma. Results of a prospective randomized trial of radiation therapy with and without CCNU, vincristine, and prednisone.

In a prospective randomized trial designed to study the effectiveness of adjuvant chemotherapy following standard surgical treatment and radiation therapy, 233 eligible patients with medulloblastoma were treated by members of the Children's Cancer Study Group and the Radiation Therapy Oncology Group. Eligible patients were randomly assigned to receive radiation therapy with or without adjuvant chemotherapy consisting of 1-(2-chloroethyl)-3-cyclohexyl-nitrosourea (CCNU), vincristine, and prednisone. The estimated 5-year event-free survival probability was 59% for patients treated with radiation therapy and chemotherapy and 50% for patients treated with radiation therapy alone, a difference which is not statistically significant. The 5-year survival probability was 65% for both groups. Although the treatment difference was not statistically significant when all patients were combined, in the small number of patients with more extensive tumors, event-free survival was better in the group receiving chemotherapy (48% vs. 0%, p = 0.006). In these latter patients the survival time is also significantly prolonged. Extent of disease (as measured by the M staging criteria described by Chang) and age at diagnosis were significantly associated with outcome; advanced disease and young age had a worse prognosis. The extent of tumor resection was not an independent prognostic factor. It is concluded that chemotherapy does not benefit patients with low-stage medulloblastoma, but may benefit those with more advanced stages of disease.

Adolescent↗

PubMed1990

Two-dimensional and Doppler echocardiographic features of coronary arteriovenous fistula. Report of three cases.

Two-dimensional (2-D) and Doppler echocardiographic features of three cases of coronary arteriovenous fistula (CAVF) were analyzed. The final diagnosis was confirmed by coronary angiography in each case. In cases 1 and 2, the CAVF arose from the right coronary artery and drained into the right atrium and right ventricle, respectively. The origin and draining site of the CAVF could be visualized by 2-D echocardiograms. The Doppler studies revealed a unidirectional flow within the lumen of the CAVF. In case 3, with a small CAVF originating from both the right coronary artery and left circumflex artery draining into the main pulmonary artery, no abnormal vascular structure could be detected by the 2-D echocardiogram; with Doppler study, a diastolic as well as systolic flow signal directed toward the distal pulmonary artery could be detected.

Adult↗

PubMed1990

Sonographic and Doppler features of infantile hepatic hemangiomas with pathologic correlation.

The sonograms of five patients with a diagnosis of infantile hepatic hemangioma were retrospectively reviewed to analyze their sonographic and Doppler characteristics. Three patients had single lesions, whereas two had multifocal involvement. All lesions except one were hypoechoic, well-circumscribed, and solid; the exception was hyperechoic. Findings of high flow, ie, large draining veins, an abrupt change in aortic caliber, and the presence of Doppler signal throughout the lesion were seen in three of five patients. The sonographic findings correlate well with the pathologic findings of multiple vascular channels separated by fibrous septa. The major differential diagnosis of infantile hepatic hemangioma includes hepatoblastoma and metastatic neuroblastoma. Although some of their sonographic features may simulate a hemangioma, large draining veins and changes in aortic caliber are not reportedly seen. Doppler flow was not seen in either of these malignant neoplasms in our study and, to date, has only been reported peripheral to three cases of hepatoblastoma and not at all in metastatic neuroblastoma. We propose an algorithmic approach dependent upon the sonographic-Doppler appearance.

Hemangioma, Cavernous↗

PubMed1990

The significance of abnormally high and low maternal serum alpha-fetoprotein levels between 14 and 25 weeks of gestation.

A total of 6,160 gravidas with gestational ages from 14 to 25 weeks were collected to quantify maternal serum alpha-fetoprotein (MSAFP) using an enzyme immunoassay kit. A level over 2.5 MoM (multiples of the median) was defined as high and a level below 0.4 MoM as low. Ninety-eight women (1.59%) had an initially high MSAFP and 88 (1.42%) a low MSAFP. In the low MSAFP group, 80% returned for a further checkup. Among them, 46% had an over-estimation of gestational age based on their last menstrual period (LMP), 28% had a normal MSAFP and 9% still had a low MSAFP level on a repeat test. Pathologic conditions in other pregnancies included a hydatidiform mole, miscarriage and pseudocyesis. One nonresponder had an ectopic pregnancy. After delivery, no major fetal abnormalities, including trisomy syndromes, were noted in pregnancies carried to term. In the high MSAFP group, 84% returned for check-up. Among them, 15% had an under-estimation of gestational age based on LMP, 16% had twin pregnancies, 46% had a normal MSAFP and 12% still had a high MSAFP on a repeat test. Pathologic conditions in the other pregnancies included one anencephaly, one hydrocephaly and 6 miscarriages. Wrong dating by LMP and false positivity were the most frequent causes of abnormal levels of MSAFP. Two gravidas had artificial abortions because of undue anxiety. MSAFP screening in Taiwan for open neural tube defects does not seem appropriate and using 0.4 MoM as a fixed low cut-off point is inadequate for trisomy syndrome screening. Maternal anxiety should be seriously considered and proper genetic counseling implemented in a screening procedure.

Anencephaly↗

PubMed1990

Growth and characterization of normal human keratinocytes in F12 serum-free medium.

In a F12 medium supplemented with epidermal growth factor (20 ng/ml), insulin (5 micrograms/ml), transferrin (5 micrograms/ml), hydrocortisone (1 microM), cholera toxin (40 ng/ml), endothelial cell growth supplement (15 ng/ml) and retinoic acid (1 x 10(-7) M) on Vitrogen coated culture dishes, normal adult and newborn human foreskin keratinocytes were cultured for 4- and 2-time with population doublings (PD) accumulated as 8 and 12, respectively. The cells grown in this medium possessed a basaloid, undifferentiated and hyperproliferating nature, with a population doubling time of about 24 hours at early passage. Between the 1st and 2nd subcultures, cell proliferation was the most active. Delaying the time of first subculture lowered the rate of cell proliferation. The keratin of the cultured cells was studied by immunoblotting and revealed the presence of permanent keratin markers of the human skin (AE1 50 kDa and AE3 58kDa) as well as a relatively high intensity of a proliferating marker (AE1 48 kDa) and a relatively low intensity of a differentiation marker (AE3 67 kDa).

Adult↗

PubMed1990

Aortic regurgitation due to aortic root intimal tear as a result of blunt chest trauma.

We report a 31-year-old male patient who sustained blunt trauma to the chest, abdomen and left knee resulting in a liver laceration, left patella fracture and aortic regurgitation. Hepatorrhaphy, open reduction of the fractured patella and resuspension of the prolapsed aortic valve secondary to the aortic root intimal tear were performed subsequently. Prompt diagnosis and aggressive intervention of such injuries can lead to successful repair of potentially fatal cardiac trauma.

Adult↗

PubMed1990

Metabolic evaluation of urolithiasis.

After detailed instruction, 62 patients with urolithiasis treated at Taichung Veterans General Hospital entered this program, which ran from September 1987 to November 1988. Based on Pak's classification, there were 13 cases (21.0%) of absorptive hypercalciuria, type I (AH-I); 12 cases (19.4%) of absorptive hypercalciuria, type II (AH-II); 16 cases (25.8%) of renal hypercalciuria (RH); 3 cases (4.8%) of hyperuricosuric calcium urolithiasis (HUCU); 11 cases (17.7%) of hypocitraturia (Hypocit); 3 cases (4.8%) of hyperoxluria (HO); one case (1.6%) of primary hyperparathyroidism (PHPT) and one case (1.6%) of infectious lithiasis. Two cases (3.2%) with no metabolic abnormalities were found. Hypocitraturia, HUCU, and HO can be the primary abnormal findings, but more often coexist with various forms of hypercalciuria as a second factor. If the coexistence is considered, hypocitraturia (33 cases, 53.2%) and HUCU (24 cases, 38.7%) were the most prevalent categories. Meanwhile, 24 cases (38.7%) had only one physiological derangement, 25 cases (40.3%) had two derangements, and 13 cases (21.0%) had three. This study indicates that metabolic evaluation can elucidate the physiological derangements of urolithiasis, so that further medical treatment can be administered selectively.

Adult↗

PubMed1990

Hepatic cyst associated with Peutz-Jeghers syndrome.

A solitary hepatic cyst, associated with Peutz-Jeghers syndrome, is described. To our knowledge, this association has not been previously reported. A developmental anomaly or hamartomatous nature of this lesion is suggested. Knowledge of this association may be helpful in the clinical diagnosis of this benign entity.

Adult↗

PubMed1990

Thymic carcinomas: histopathological varieties and immunohistochemical study.

Thirteen cases of primary thymic carcinomas are described. The patients' ages ranged from 19 to 64 years, with a median of 40 years. Nine of them were male. Chest pain with or without cough was the main presenting symptom. No patient had myasthenia gravis. Five histological types were identified; two were undifferentiated (lymphoepithelioma-like) carcinoma, one was a clear-cell carcinoma, two were mixed squamous and small-cell carcinoma, and six were squamous cell carcinoma. All the tumors were variably positive for anti-keratin antibody AE1 and AE3, but negative for AE2. Anti-neuron specific enolase antibody was useful in identifying and confirming the small-cell carcinoma component of the mixed carcinomas. Anti-epithelial membrane antigen antibody aided in revealing the glandular structures in mixed adenosquamous and small-cell carcinomas. Thymic carcinomas were histopathologically differentiated from thymomas by their malignant cytological appearance, increased mitotic activity, and central tumor necrosis. All six patients with pure squamous-cell carcinoma were still alive, with a median survival time of 27 months. All but one of the other patients of different histological types died, the exception being a recent case of mixed adenosquamous and small-cell carcinoma; their median survival was 19.5 months, or 18 months when the latter surviving case is included. The prognosis of patients with pure squamous-cell carcinoma was better.

Adult↗

PubMed1990

Longitudinal study of clinical and radiological progression in psoriatic arthritis.

Our aim was to document the progression of psoriatic arthritis in 126 patients prospectively evaluated for a minimum of 5 years. Clinical and laboratory variables and radiographs of the hands and feet, recorded at first and last assessment, were compared to document change in the degree of joint inflammation and damage. During followup there was a significant increase in the use of a number of therapeutic modalities, in particular, gold, PUVA, retinoids and intraarticular glucocorticoid injections. Evidence of inflammatory arthritis was decreased at last assessment relative to presentation. The rate of progression of joint damage, calculated by the ratio of the number of damaged joints to the duration of arthritis in years, actually decreased during followup from 1.97/year to 0.5/year. Nevertheless the proportion of patients with at least 5 damaged joints doubled from 19 to 41% during the study. Thus, despite active treatment and a reduction in joint inflammation and in rate of damage, psoriatic arthritis may be a progressively deforming arthritis, even during 5 years of followup.

Adult↗

PubMed1990

Synthesis and regulation of lipoprotein lipase in the hippocampus.

Lipoprotein lipase (LPL) expression was determined in adult rat hippocampus and compared to enzyme expression in other brain regions. Hippocampus LPL mRNA levels were at least 2.5-fold higher than those detected in the cerebral cortex, cerebellum, and remaining brain regions. Enzyme mass and activity levels in the hippocampus were also increased to a similar degree. De novo synthesis of LPL in the hippocampus was confirmed by [35S]methionine-labeling of the tissue and identification of a 57 kDa protein obtained by immunoprecipitation. Addition of an excess amount of bovine LPL completely prevented the immunoprecipitation of this protein. The effect of nutritional modulations on brain LPL activity was determined after a 12-h fast. While no significant changes were observed in other regions of the brain, hippocampus LPL activity in fasted rats increased by 60% compared to the fed control group. Simultaneously, fasting reduced adipose LPL activity by 60%. Intraperitoneal injection of ACTH over a 5-day period had no effect on hippocampus LPL activity, while adipose LPL levels increased 2.3-fold and heart LPL levels decreased 1.4-fold. We conclude that LPL is synthesized, active and regulated in a tissue-specific manner in the adult rat hippocampus.

Adipose Tissue↗

PubMed1989

Diacytosis of asialoglycoprotein in isolated hepatocytes is dependent on the structure of ligand and cellular distribution of the receptors.

Diacytosis, degradation and retention of 125I-labeled asialoorosomucoid (ASOR), its reduced and carboxymethylated N-terminal cyanogen bromide-cleaved fragment (RC-ASCNBr-I) and asialofetuin preloaded into isolated rat or rabbit hepatocytes for various periods of time were compared. In rat hepatocytes preloaded with a saturating concentration (3.10(-8) M) of the ligands, the proportion of the preloaded ligands distributed to degradation and diacytosis was fairly constant during 4 h of preincubation. In addition, a small portion of the preloaded ligands was neither diacytosed nor degraded, but was retained intracellularly. Diacytosis of 125I-ASOR (29%) was greater than that of either 125I-RC-ASCNBr-I (23%) or 125I-asialofetuin (15%). Diacytosis of 125I-ASOR, when preloaded in the presence of 5 microM colchicine, was significantly enhanced by 79% (increasing from 29% to 52%), whereas those of 125I-RC-ASCNBr-I and 125I-asialofetuin were not significantly altered (with average increases of 14% and 19%, respectively). The fraction of the preloaded 125I-asialofetuin (69%) and 125I-RC-ASCNBr-I (68.6%) that was degraded was slightly higher than that of 125I-ASOR (64%) and all was decreased by colchicine. The fraction of all three ligands retained by the cells was increased 2- to 4-fold by colchicine. The extents of retention of 125I-asialofetuin and 125I-ASCNBr-I were greater than that of 125I-ASOR, particularly after preloaded for more than 2 h. Preloading of the cells with ligands at a non-saturating concentration (6.5.10(-10) M) did not change these patterns of ligand distribution. Conjugation of diphtheria toxin fragment A (DTA) to ASOR or RC-ASCNBr-I also did not significantly alter the pattern of ligand distribution. In rabbit hepatocytes containing more asialoglycoprotein receptors than rat cells, 125I-ASOR was diacytosed to a greater extent (50%, -colchicine; 61%, + cholchicine) but degraded to a lesser extent (33%, -colchicine; 13%, + colchicine) than was observed in rat cells. The extent of retention of 125I-ASOR in rabbit cells was also greater than that in rat cells. A similar pattern of differences between rabbit and rat hepatocytes was observed for 125I-DTA-ASOR. These results indicate that intracellular sorting of internalized asialglycoproteins between diacytosis and degradation is dependent on both the structure of the ligand and the distribution of the cellular receptors.

Animals↗

PubMed1989

Structure of spheroidene in the photosynthetic reaction center from Y Rhodobacter sphaeroides.

The structure of the reaction center of Y Rhodobacter sphaeroides has been solved at 3 A resolution, using the atomic coordinates of the reaction center from the carotenoidless mutant R26 Rhodobacter sphaeroides. The structure has been refined by a stimulated annealing with the computer program X-PLOR, leading to a crystallographic R factor of 0.22 using reflections between 8 and 3 A. The spheroidene molecule which is bound to the Y reaction center has been fitted in the electron density map as a 15-cis isomer with a highly asymmetric structure. The cis-bond is located at proximity from ring 1 of the accessory bacteriochlorophyll on the inactive M side. The nature of the cis-bond was confirmed by resonance Raman spectra obtained from Y reaction center crystals. The structure of spheroidene in Y reaction center is compared to that proposed for 1,2-dihydroneurosporene in Rhodopseudomonas viridis reaction center crystals.

Bacterial Proteins↗

PubMed1989

Study on the variables affecting toxicity of hybrid toxins. The effect of different target cell receptor distribution and toxin binding chain.

Disulfide conjugates of diphtheria toxin (DT) and its fragment A (DTA) to asialoorosomucoid (ASOR) were prepared. The toxicity of the conjugates were compared with DT in isolated rat, rabbit and guinea pig hepatocytes containing different concentration of asialoglycoprotein receptors (Biochim. Biophys, Acta 942, 57, 1988). In rat hepatocytes DTA-ASOR was highly toxic with half-maximal inhibitory concentration (IC50) of protein synthesis occurring at 4 +/- 3.10(-11) M (n = 7) which was much lower than that of DT DT (7.8 +/- 9.8.10(-9) M, n = 7). In rabbit hepatocytes toxicity of the conjugate (IC50 = 5.4 +/- 4.9.10(-10) M, n = 7) was higher than that of DT (IC50 = 5 +/- 4.10(-11) M, n = 7). In guinea pig hepatocytes, DTA-ASOR was not toxic at concentration below 10(-8) M, although DT was highly toxic (IC50 = 1.8 +/- 1.4.10(-10), n = 3). In the presence of 5 microM colchicine, the toxicity of DTA-ASOR in rat and rabbit hepatocytes increased by 10-fold, while in guinea pig hepatocytes it became detectable with an IC50 of 1.2 +/- 0.8.10(-9) M (n = 3). The toxicity of DT in the rat cells was also enhanced 10-fold by colchicine, but not at all in either the rabbit or the guinea pig cells. Addition of isolated diphtheria toxin fragment B (DTB) did not affect significantly the toxicity of DTA-ASOR in all three hepatocytes and that of DT in rat hepatocytes, but reduced toxicity of DT more than 20-fold in the rabbit and guinea pig cells. Toxicity of DT-ASOR in rat hepatocytes was the same as DTA-ASOR both in the absence and presence of colchicine, and abolished completely by excess ASOR, but not by DTB. Toxicity of DT-ASOR in rabbit hepatocytes was 40-times higher than DTA-ASOR, enhanced 10-fold by cochicine and reduced more than 30-fold by excess ASOR, but only slightly by DTB. These results indicate that entry of DTA from DTA-ASOR involve a DTB-independent translocation mechanism which can be as efficient as the DTB-dependent mechanism used by DT in the rabbit and guinea pig cells. The entry of both conjugates appeared to be mediated by the asialoglycoprotein receptors. However, the DTB moiety of DT-ASOR could function only in the DT-sensitive cells indicating the lack of a DTB-mediated translocation in the DT-resistant cells.

Animals↗

PubMed1989

[Chondrosarcoma of the rib--a case report].

Chondrosarcoma is second in frequency only to osteogenic sarcoma as a malignant tumor of bone, and constitutes 17 to 22% of all bone tumors. However, chondrosarcoma is the most common malignant tumor of the sternum or rib. The natural history of chest wall chondrosarcoma is one of slow growth and local recurrence. Wide excision is the main treatment, but usually plastic surgery is needed for chest wall reconstruction. A 29-year-old male patient visited to local clinic due to URI symptoms (eg: cough, rhinorrhea). Routine chest X-ray examination showed a huge tumor within L't chest cavity and chondrosarcoma was proved via tissue biopsy. P't underwent surgery for total removal of the tumor and corresponding rib (3rd rib) and the chest wall defect was repaired with bovine pericardium. So far, after follow-up and treatment for 4 months, there is no evidence of recurrence.

Adult↗

PubMed1989

Structure of a second crystal form of Bence-Jones protein Loc: strikingly different domain associations in two crystal forms of a single protein.

We have determined the structure of the immunoglobulin light-chain dimer Loc in a second crystal form that was grown from distilled water. The crystal structure was determined to 2.8-A resolution; the R factor is 0.22. The two variable domains are related by local 2-fold axes and form an antigen binding "pocket". The variable domain-variable domain interaction observed in this crystal form differs from the one exhibited by the protein when crystallized from ammonium sulfate in which the two variable domains formed a protrusion (Chang et al., 1985). The structure attained in the distilled water crystals is similar to, but not identical with, the one observed for the Mcg light-chain dimer in crystals grown from ammonium sulfate. Thus, two strikingly different structures were attained by this multisubunit protein in crystals grown under two different, commonly used, crystallization techniques. The quaternary interactions exhibited by the protein in the two crystal forms are sufficiently different to suggest fundamentally different interpretations of the structural basis for the function of this protein. This observation may have general implications regarding the use of single crystallographic determinations for detailed identification of structural and functional relationships. On the other hand, proteins whose structures can be altered by manipulation of crystallization conditions may provide useful systems for study of fundamental structural chemistry.

Bence Jones Protein↗

PubMed1989

Stimulatory effects of atrial natriuretic factor on phosphoinositide hydrolysis in cultured bovine aortic smooth muscle cells.

The effects of atrial natriuretic factor (ANF) on phosphoinositide hydrolysis were examined in preparations of cultured bovine aortic smooth muscle cells. In homogenates or particulate fractions from cultured bovine aortic smooth muscle cells, ANF and atriopeptin I increased the formation of inositol phosphates and GTPase activity. The effects on inositol phosphates were markedly enhanced with guanosine 5'[gamma-thio]triphosphate. Both atrial peptides also stimulated the formation of diacylglycerol in intact cultured cells. In these experiments, atriopeptin I was about 10-fold more potent than ANF. These studies indicate that atrial peptides have stimulatory effects on phosphoinositide hydrolysis which are mediated through a guanine nucleotide regulatory protein. The greater potency of atriopeptin I on GTPase activity and the accumulation of inositol phosphates suggests that the nonguanylate cyclase-coupled receptor for ANF (ANF-R2) mediates the stimulatory effects of ANF on phosphoinositide hydrolysis through a guanine nucleotide regulatory protein.

Animals↗

PubMed1989

The cyanogen bromide fragment I of asialoorosomucoid is transported more efficiently than asialoorosomucoid in rat hepatocytes.

Cultured rat hepatocytes internalized and degraded 125I-labeled asialoorosomucoid (125I-ASOR) through asialoglycoprotein receptor at rates about half that of its cyanogen bromide fragment I (125I-ASCNBr-I). Reduction and carboxymethylation of the fragment resulted in decreased rates of internalization and degradation which were still greater than those of 125I-ASOR. In the presence of 5 microM colchicine, degradation of all three ligands was inhibited. However, the intracellular level of 125I-ASOR at steady state remained unchanged, while those of the fragments increased continuously. Study of the binding of these ligands to hepatocytes at 4 degrees C indicated that there was no significant difference in binding parameters between ASOR, ASCNBr-I and RC-ASCNBr-I (reduced and carboxymet ASCNBr-I). Studies of the fate of these ligands preloaded in the cell at 37 degrees C indicated that a higher fraction of the internalized ASOR than of the fragments was released by diacytosis. In contrast to ASOR, diacytosis of the fragments was not enhanced by colchicine. Studies of the distribution of intracellular ligands by Percoll density gradient centrifugation indicated that they were internalized initially into two early endosomal compartments of d = 1.037 g/ml and d = 1.045 g/ml. In the presence of colchicine, accumulation of the ligands in a third endosomal compartment of d = 1.08-1.095 g/ml was revealed, while in the presence of leupeptin accumulation of the ligands in lysosomes was observed. The results of a kinetic analysis indicated that both cyanogen bromide fragments were transported to all these compartments more rapidly than was ASOR. It appears that they are internalized and degraded more rapidly than ASOR due to a more efficient sorting of the internalized ligand into the pathway of lysosomal degradation.

Animals↗