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Biomedical subjects

C K Chang

Publications and source records attributed to C K Chang.

At least 19 recordsLinked to original sources
PubMed1992

Immunoelectron microscopy of carbonic anhydrase isozyme VI in rat submandibular gland: comparison with isozymes I and II.

Carbonic anhydrase (CA) was purified from the saliva of pilocarpine-treated rats by inhibitor-affinity chromatography, and its localization in the rat submandibular gland was studied by the indirect immunoperoxidase technique using a monoclonal antibody (MAb) raised against the enzyme. SDS-polyacrylamide gel electrophoresis of the CA VI gave three bands of 33, 39, and 42 KD. Enzyme digestion experiment showed that the 42 KD molecule was degraded into the 39 KD molecule and the 39 KD molecule into the 33 KD molecule. The cleavage of the 42 KD molecule was independent and that of the 39 KD molecule was dependent on endo-beta-N-acetylglucosaminidase F. The 42 KD molecule was detected in the CA purified from the pilocarpine-treated but not the untreated salivary gland. The MAb recognized all the three components of the enzyme. Immunostaining for CA VI was seen in the cytosol and secretory granules of serous acinar cells and in the duct luminal contents. Staining specific for erythrocyte CA (CA I and CA II) was observed in the cytosol of the epithelial cells of granular, striated, and excretory ducts. Among these duct cells, the agranular varieties in the granular and excretory ducts were essentially devoid of the immunoreactivity.

Animals↗
PubMed1992

Surgical management of an unusual osteomyelitis involving posterior elements in lumbar spine. A case report.

Improper and invasive management of low back pain may lead to an unexpected tragedy, vertebral osteomyelitis. A 30-year-old female patient suffering from low back pain after a lumbar strain called on a herbal therapist and was given a herb massage with some unknown medication. Unfortunately, a persistent painful ulcer with discharge developed over her back. She was referred to our clinic shortly after where x-ray showed bony destruction over the spinous process, facet, and lamina of L4. Fistulectomy, debridement and spinal fusion were performed. A satisfactory outcome was finally achieved.

Adult↗
PubMed1992

Traumatic tension pneumocephalus--intracerebral pneumatocele: a case report.

An 18-year-old Chinese man, suffering from head injury in a motorcycle accident, with right traumatic frontal intracerebral hemorrhage and frontal bone fractures, underwent emergency craniotomy with evacuation of hematoma at a local out-patient clinic and three months later, he suffered from CSF rhinorrhea. Headache, nausea and vomiting developed a week prior to admission. Tension pneumocephalus was diagnosed by computed tomography (CT) scan and plain skull X-ray. The fistula tract of the ethmoid sinus was investigated by radioisotope albumin (RISA) cisternography. The patient subsequently underwent emergency craniotomy for decompression. During the operation, we found that the intracerebral pneumatocele in the right frontal lobe communicated with the ipsilateral ethmoidal sinus, through which extracranial air ingressed and CSF egressed. This pneumatocele was unroofed and the fistula was temponaded by pericranial muscles and the Gelfomas sealed by tissue glue. Finally duraplasty was performed. Follow-up CT scan revealed that pneumocephalus subsided and the patient was cured of CSF rhinorrhea on discharge. As a surgical emergency, tension pneumocephalus can be successfully treated only by early diagnosis and early treatment.

Adolescent↗
PubMed1991

The active site structure of E. coli HPII catalase. Evidence favoring coordination of a tyrosinate proximal ligand to the chlorin iron.

E. coli produces 2 catalases known as HPI and HPII. While the heme prosthetic group of the HPII catalase has been established to be a dihydroporphyrin or chlorin, the identity of the proximal ligand to the iron has not been addressed. The magnetic circular dichroism (MCD) spectrum of native ferric HPII catalase is very similar to those of a 5-coordinate phenolate-ligated ferric chlorin complex, a model for tyrosinate proximal ligation, as well as of chlorin-reconstituted ferric horseradish peroxidase, a model for 5-coordinate histidine ligation. However, further MCD comparisons of chlorin-reconstituted myoglobin with parallel ligand-bound adducts of the catalase clearly rule out histidine ligation in the latter, leaving tyrosinate as the best candidate for the proximal ligand.

Binding Sites↗
PubMed1991

Purification of cytochrome cd1 nitrite reductase from Pseudomonas stutzeri JM300 and reconstitution with native and synthetic heme d1.

Cytochrome cd1 nitrite reductase has been purified from Pseudomonas stutzeri strain JM 300. This enzyme appears to be a dimer with a subunit molecular mass of 54 kDa and its isoelectric point is determined to be 5.4. The N terminus of amino acid sequence has strong homology with that of nitrite reductase from P. aeruginosa. The apoprotein of this enzyme has been reconstituted with native and synthetic heme d1. The nitrite reductase activity measured by NO and N2O gas evolution can be restored to 82% of the activity of the original enzyme when the protein was reconstituted with the native heme d1 and to 77% of the activity when reconstituted with the synthetic heme d1. The absorption spectra of both reconstituted enzymes are essentially identical to that of the original nitrite reductase. These results further substantiate the novel dione structure of heme d1 as proposed. The loss of NO2- reducing activity in the absence of heme d1 and its restoration by addition of heme d1 provides further evidence that heme d1 plays a key role in the conversion of NO2- to NO and N2O.

Amino Acid Sequence↗
PubMed1991

Histochemistry of tartrate-resistant acid phosphatase and carbonic anhydrase isoenzyme II in osteoclast-like giant cells in bone tumours.

Using routinely processed, paraffin-embedded tissue specimens, osteoclast-like giant cells in giant cell tumour of bone (GCT), chondroblastoma, osteoblastoma and osteoblastic osteosarcoma were examined histochemically for osteoclast-specific enzymes tartrate-resistant acid phosphatase (TRAP) and carbonic anhydrase isoenzyme II (CA-II). Osteoclast-like giant cells and some mononuclear cells possessed TRAP activity. These were further classified with respect to CA-II immunoreactivity, i.e. cells with CA-II were seen in GCT and chondroblastoma, while those in osteoblastoma and osteoblastic osteosarcoma were negative for CA-II. All the cellular components in malignant fibrous histiocytoma and various extraosseous inflammatory lesions including malignant giant cells and macrophage polykaryons were negative for both TRAP and CA-II. These results indicate that osteoclast-like giant cells in GCT, chondroblastoma, osteoblastoma and osteoblastic osteosarcoma are all osteoclasts and generated by fusion of mononuclear cells with the same histochemical characteristics as osteoclast-like giant cells. The difference in CA-II immunoreactivity suggests the functional or maturational difference between osteoclast-like giant cells in GCT and chondroblastoma and those in osteoblastoma and osteosarcoma.

Acid Phosphatase↗
PubMed1991

Photosensitization by synthetic diporphyrins and dichlorins in vivo and in vitro.

A group of polycarboxylic diporphyrins, two dichlorins and a porphyrin-chlorine dimer, with rings linked by methylene groups, were examined to help identify structures which can mediate photodynamic tumor eradication in vivo. Among the features sought were short persistence of normal tissue photosensitization and substantial absorbance at wavelengths longer than 630 nm. Both objectives were achieved, with pertinent structure-activity relationships partly characterized. The relative hydrophobicity of the different sensitizers was an important determinant of their accumulation in cell culture, but not of in vivo effectiveness. These compounds showed affinity for protein and high-density lipoprotein components of serum. Their distribution may be mediated by a different mechanism than that which occurs with more hydrophobic sensitizers like hematoporphyrin derivative which have greater affinity for low-density lipoproteins and less for protein components of serum, as compared with the products examined in this study.

Animals↗
PubMed1991

Identification, characterization, and sequence analysis of a cDNA encoding a phosphoprotein of human herpesvirus 6.

Human herpesvirus 6 (HHV-6)-specific monoclonal antibody (Mab) 9A5D12 reacted with the nucleus of HHV-6 strain GS-infected cells and immunoprecipitated a phosphorylated polypeptide with an approximate size of 41 kDa, designated HHV-6 P41. A 110-kDa polypeptide was also immunoprecipitated by the MAb. These polypeptides were synthesized early in infection, and the synthesis was greatly reduced by phosphonoacetic acid. Polypeptides with identical sizes were recognized by the MAb from cells infected with an additional eight HHV-6 strains. A 2.1-kb cDNA insert was identified from an HHV-6(GS) cDNA library constructed in the lambda gt11 expression system by using MAb 9A5D12. This cDNA insert hybridized specifically with viral DNA from HHV-6 strains GS and Z-29 and with two predominant transcripts with approximate sizes of 2.5 and 1.2 kb from infected cells. The reactivity of the MAb with a fusion protein expressed in the prokaryotic vector suggested that the cDNA encodes a 62- to 66-kDa protein. Analysis of the nucleotide sequence of the cDNA insert revealed a 623-amino-acid-residue single open reading frame of 1,871 nucleotides, with an open 5' end. The predicted polypeptide is highly basic and contains a long stretch of highly hydrophobic residues localized to the carboxy terminus. The amino-terminal half of the predicted HHV-6 protein from the cDNA shows significant homology with the UL44 gene product of human cytomegalovirus, coding for the ICP36 family of early-late-class phosphoproteins. Two TATA boxes are located at nucleotide positions 668 and 722 of the cDNA. In vitro translation of RNA transcribed in vitro from the cDNA resulted in the synthesis of a 41-kDa polypeptide only. This polypeptide was readily immunoprecipitated by MAb 9A5D12, and its partial peptide map was identical to that of the 41-kDa polypeptide detected in infected cells. Together, these results indicate that the HHV-6 P41 is encoded within a gene coding for a larger protein.

Amino Acid Sequence↗
PubMed1991

Effect of loading conditions on peak aortic flow velocity and its maximal acceleration.

Aortic flow measurement with Doppler echocardiography has become a non-invasive technique in clinical practice. In the present animal study, we evaluated the flow-derived parameters such as peak velocity (PV) and its maximal acceleration (MA) as indices of ventricular contractility independent of the loading status. Eight pentobarbital-anesthetized cats were maintained with artificial ventilation. The chest was opened to place an electromagnetic flow probe around the ascending aorta for recording pulsatile aortic flow. PV and MA were measured from the flow tracing and on-line electronic differentiation. Intravenous infusions of dobutamine (DT), angiotensin II (AII) and dextran (DN) were used to alter the cardiac inotropism, afterload and preload, respectively. At a steady state (approximately 5 min after infusion), DT increased the PV from 56 +/- 9 to 78 +/- 14 cm/sec (p less than 0.05) and MA from 1302 +/- 108 to 1699 +/- 117 cm/sec2 (p less than 0.05). In response to AII infusion, PV was slightly reduced (60 +/- 7 to 55 +/- 6 cm/sec, p less than 0.05) while MA was also reduced mildly but significantly (1219 +/- 109 to 1099 +/- 109 cm/sec2, p less than 0.05). Dextran infusion produced a marked increase in PV (48 +/- 7 to 82 +/- 13 cm/sec, p less than 0.05) while the increase was slightly less for MA (1089 +/- 95 to 1604 +/- 109 cm/sec2). The results indicated that inotropic stimulation markedly increased both PV and MA. PV and MA responded slightly but significantly to afterload alterations. (8.3% vs 9.8%, respectively). Both PV and MA increased markedly to the preload increment.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II↗
PubMed1990

Expression of major histocompatibility complex class II antigens and interleukin-1 by epithelial cells of Warthin's tumor.

The immunoreactivity for class II antigens of the major histocompatibility complex and interleukin-1 (IL-1) in Warthin's tumor (WT) cells was studied. In addition to macrophages, dendritic cells, and capillary endothelia, the luminal tumor cells and some keratinocytes in the metaplastic squamous foci exhibited immunoreactivity for both class II antigens and IL-1. The distribution of the class II antigens in the luminal tumor cells was limited to their basolateral membrane. These data, together with previous findings, strongly suggest that the luminal tumor cells of WT introduce the luminal antigen to the underlying lymphoid tissue and, thus, act as an antigen-presenting cell.

Adenolymphoma↗
PubMed1990

Modelling heme d1. The spectral properties of copper(II) porphyrindiones.

The heme d1 macrocycle of Ps. aeruginosa dissimilatory nitrite reductase is an iron porphyrin-3,8-dione with a 17-acrylate substituent. We have compared the RR properties of Cu-d1, the copper(II) TME of extracted heme d1, with those of models that differ only with respect to the acrylate: Cu-17-acrylate mesoporphyrin-3,8-dione (2) and Cu-mesoporphyrin-3,8-dione (3). The RR spectrum of Cu-d1 is very similar to that of 2, including v(C = O) at approximately 1720 cm-1. Replacement of the acrylate with propionate changes the spectrum markedly. For example, the v(C = O) mode of 3 shifts to 1712 cm-1, and peaks of Cu-d1 and 2 at approximately 1400 and approximately 1535 cm-1 are shifted or absent from the spectrum of 3. FTIR spectra of 2 and 3 also differ in their voxo(C = O) frequencies. The acrylate thus has a surprisingly strong influence on the electronic structural and spectral properties of heme d1. These data provide a foundation for studies of the novel biological porphyrindione macrocycles.

Acrylates↗
PubMed1990

Modulation of rat salivary carbonic anhydrase by pilocarpine.

Carbonic anhydrase (CA) from pilocarpine-treated (1.5 mg/kg body weight; i.p.) rat saliva was purified by inhibitor affinity chromatography. The purified CA contained Mr 42000 and 39000 proteins on sodium dodecyl sulfate polyacrylamide gel electrophoresis. In addition to the erythrocyte isozyme (Mr 30000), salivary gland CA from rats without pilocarpine stimulation contained Mr 39000 and 33000 proteins and that from rats with pilocarpine stimulation also contained Mr 42000 protein. The 42000Da and 39000Da proteins bound to concanavalin A and were cleaved by endo-beta-N-acetylglucosaminidase F to become 39000Da and 33000Da proteins. These results suggest that, under the influence of pilocarpine, salivary gland cells synthesize a new glycoprotein, Mr 42000, via N-linked glycosylation of a 39000Da glycoprotein, which is the only secretory glycoprotein in the unstimulated salivary gland and is produced by N-linked glycosylation of a 33000Da polypeptide.

Animals↗