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H C Ho

Publications and source records attributed to H C Ho.

At least 37 records · Page 2Linked to original sources
PubMed1998

Conformationally restricted carbamate inhibitors of horse serum butyrylcholinesterase.

Conformationally restricted carbamate inhibitors, exo-2-norbornyl-N-butylcarbamate (1), endo-2-norbornyl-N-butylcarbamate (2), l-adamantyl-N-butylcarbamate (3), and 2-adamantyl-N-butylcarbamate (4) as active site-directed irreversible inhibitors of horse serum butyrylcholinesterase are investigated for values of the dissociation constant (KI), the carbamylation constant (k2), and the bimolecular rate constant (ki). Compound 1 is the most potent inhibitor of the enzyme and the values of KI and ki are 20 nM and 1.1 x 10(5) M-1sec-1, respectively.

Animals↗
PubMed1998

Purification, characterization and complete amino acid sequence of nuclease C1 from Cunninghamella echinulata var. echinulata.

It is known, from the zymogram method of nuclease activity assay, that the crude extracts of Cunninghamella echinulata var. echinulata contained at least three distinct extracellular nucleases. Among them, the major form was 30 kDa in molecular mass and termed nuclease C1. In this report, nuclease C1 was purified to apparent homogeneity by chromatography on Cibacron blue-3GA, phenyl-Sepharose 4B and HiTrap Heparin. Nuclease C1 acquired enzymatic activity in the presence of Mn2+ or Mg2+ and was inhibited by EDTA. The activity was maximal at pH 7-8.5. The primary structure of nuclease C1 was completely determined using enzymatic digestion and gene cloning. The N-terminal 49 residues of nuclease C1 were first elucidated from a tryptic digest. Two degenerate upstream primers were subsequently designed to amplify the cDNA encoding nuclease C1. The resulting protein sequence of nuclease C1 was shown to be composed of 252 residues. It was intriguing to find that the protein sequence of nuclease C1 showed significant similarities with the sequences of the mitochondrial nucleases of Saccharomyces cerevisiae (44% identity) and Schizosaccharomyces pombe (42% identity). Residue His87 of nuclease C1 was postulated to be located at the active site from sequence similarity with secreted nuclease from Serratia marcescens.

Amino Acid Sequence↗
PubMed1998

Single-column purification of syncephapepsin--an aspartic proteinase from Syncephalastrum racemosum.

Syncephapepsin is a fungal aspartic proteinase from Syncephalastrum racemosum. By using the property of syncephapepsin after having increased activity at higher temperature, two rapid purification protocols were developed. In the former case, a crude extract was initially diluted fivefold with an activity assay buffer and heated at 50 degrees C overnight. In this situation, syncephapepsin would digest most of the proteins that the crude extract contained. Subsequently, syncephapepsin of the crude extract was precipitated from 50 to 70% of ammonium sulfate and the preparation was then directly applied to the Superdex 200 HR FPLC column. In this manner, syncephapepsin was rapidly purified to apparent homogeneity within 24 h. In this report, an alternative method of purification is also provided. Compared with the procedure mentioned above, the heating step was proceeded after FPLC chromatography through which the same result was obtained. Using cytochrome c and RNase A as substrates, the cleavage sites of both substrates were identified by HPLC peptide mapping. The results showed that syncephapepsin had a broad specificity. Residues recognized to be cleaved were primarily those of trypsin and chymotrypsin and Lys was the most susceptible.

Amino Acid Sequence↗
PubMed1997

Purification and characterization of tilapia (Oreochromis mossambicus) deoxyribonuclease I--primary structure and cDNA sequence.

DNase I of tilapia (Oreochromis mossambicus) was purified to homogeneity. Tilapia DNase I is most active at pH 8.5 with Mg2+ as activator. The Ca2+/Mg2+ pair has a synergistic effect on activation. The enzyme is readily inactivated by heating above 55 degrees C, but is not inactivated by trypsin or 2-mercaptoethanol under alkaline conditions, with or without CaCl2. Its isoelectric point is 6.0. The 258-amino-acid sequence of tilapia DNase I was derived from overlapping sequences of tryptic, chymotryptic and CNBr peptides. The purified enzyme has two variants differing by a single Lys-->Arg mutation at position 125. The polypeptide chain has one disulfide bridge and one carbohydrate side chain. By mass spectrometry, the purified enzyme shows many molecular mass forms differing by Lys/Arg substitution and sugar-chain length. The major form has a molecular mass of 30,914 Da. A 1061-bp nucleotide sequence for the cDNA of tilapia DNase I, obtained by gene cloning and DNA sequencing, contains an ORF coding for a putative 26-residue transmembrane peptide and the mature DNase I polypeptide.

Amino Acid Sequence↗
PubMed1996

Identification of a fungal protein of Syncephalastrum racemosum as aspartic proteinase.

During purification of fungal deoxyribonuclease (DNase) from Syncephalastrum racemosum, a protein which was functionally unknown and persistently existed in the DNase-containing fractions through chromatography over DEAE-cellulose, hydroxylapatite, and phenyl-Sepharose was identified. The protein was finally separated from DNase after affinity chromatography on a cibacron blue-Sepharose column and purified to apparent homogeneity after gel chromatography on a Superdex 200 HR column. Ten tryptic peptides of this protein were isolated and sequenced. Searching in the sequence data bank with the aid of the computer program PC/Gene, we found that this protein was highly homologous to aspartic proteinases, such as pepsin and rhizopuspepsin. Because of its fungal origin and because the protein indeed showed catalytic cleavage on peptide bonds of bovine serum albumin, RNase, and carbonic anhydrase, we termed this protein syncephapepsin. The molecular weight of syncephapepsin is 38,000 daltons, based on gel filtration and sodium dodecyl sulfate-polyacrylamide electrophoresis.

Amino Acid Sequence↗
PubMed1996

Prognostic factors of primary aldosteronism.

BACKGROUND: Primary aldosteronism (PA) is a rare but potentially curable cause of hypertension. Between October 1982 and November 1994, 30 patients of PA received unilateral adrenalectomy with a long-term follow up (mean:60.3 months). Nineteen (63.3%) cases were cured (Group 1); 11(36.7%) cases were improved (Group 2). The purpose of this study was to determine prognostic factors after surgery in patients with PA. METHODS: A retrospective analysis was performed regarding age and sex of the patients, duration of hypertension, family history of hypertension, preoperative blood pressure, plasma aldosterone concentration (PAC), plasma renin activity (PRA) and efficacy of spironolactone on blood pressure between both groups. End-organs (including kidney, heart, retina and brain) involvement was evaluated and compared. Adrenalectomy and renal biopsy specimen for pathology were similarly evaluated. RESULTS: The duration of hypertension was longer in Group 2 than in Group 1 (8.18 +/- 4.94 vs 5.21 +/- 4.24 years). The efficacy of spironolactone on blood pressure (BP) was positive in 81.8% of Group 1 and 16.7% of Group 2. Adrenal cortical adenoma in 24 cases with a cure rate of 70.8% (17/24) and adrenal cortical macronodular hyperplasia in 6 cases with a cure rate of 33.3% (2/6) were noted. Group 2 had more end-organs involvement than Group 1. The severity of histopathological change of the renal biopsy was similar. CONCLUSIONS: This study suggests that preoperative response of blood pressure to spironolactone administration predicts the postoperative prognosis of hypertension in patient with PA. Long duration of hypertension and involvement of two or more end-organs were poor prognostic factors. Excellent results can be achieved by unilateral adrenalectomy in adrenal cortical adenoma and fair results, in adrenal cortical macronodular hyperplasia.

Adolescent↗
PubMed1996

Colon perforation, bilateral pneumothoraces, pneumopericardium, pneumomediastinum, and subcutaneous emphysema complicating endoscopic polypectomy: anatomic and management considerations.

A case of colonoscopic polypectomy complicated by perforation, pneumoperitoneum, bilateral pneumothoraces, pneumopericardium, pneumomediastinum, and subcutaneous emphysema is presented. The anatomic basis for the various clinical presentations of extraluminal air following colonoscopy as well as the option of conservative therapy of select cases of perforation is discussed.

Aged↗
PubMed1996

Electronic and local anesthesia: a clinical comparison for operative procedures.

The comfort on administration and effectiveness of electronic and local anesthesia for operative procedures, as perceived by clinicians and patients, were compared based on a 5-point Lickert scale, and a survey to solicit patient's feedback on the use of electronic anesthesia was conducted. Thirty patients, who required restorations on similar teeth bilaterally, and 10 clinicians were involved in the study. The two teeth in each patient were randomly restored under either electronic or local anesthesia. Administration of electronic anesthesia was perceived to be significantly more comfortable than that of local anesthesia, by both clinicians and patients. Local anesthesia was perceived to be significantly more effective by both evaluator groups, but 93.3% of the patients still preferred electronic anesthesia and would use it again. Minor after effects in some patients included redness of skin and briefly lingering sensation. All patients found electronic anesthesia easy to use, and most of the patients (93.3%) thought that the system was good to excellent.

Adult↗
PubMed1995

[Community-based cervical cancer screening in seven townships in Taiwan].

Cervical cancer is the leading malignant neoplasm in women in Taiwan. In order to compare the validity of various cervical neoplasia screening methods, estimate the prevalence of low- and high-grade squamous intraepithelial lesions (LSIL and HSIL), and identify risk factors for LSIL and HSIL, a community-based cervical neoplasia screening program was implemented in Sanchi, Chutung, Potzu, Kaohsu, Makung, Huhsi, and Paihsa townships, Taiwan. Both cervical smears and cervicograms were used for the screening of cervical neoplasia. Subjects who had positive cervical smears, cervicogram, or both, were further confirmed by colposcopy-guided biopsy. A total of 10,628 married women aged 30 to 64 years were recruited from seven study townships which gave a response rate of 25.2%. Among 667 subjects who screened positive, 555 (82%) underwent colposcopy-guided biopsy. The age-adjusted prevalence was 3.4% for LSIL and 1.7% for HSIL. The biopsy-confirmed rates for cervical smear-detected LSIL and HSIL were 62.8% and 80.6%, respectively; while 56.6% of minor lesions and 22.2% of major lesions identified by cervicogram were biopsy-confirmed as LSIL and HSIL, respectively. The sensitivity of detecting LSIL was higher for cervicograms (79.3%) than for cervical smears (16.7%), and cervicograms had a lower sensitivity in detecting HSIL (48.4%) than cervical smears (90.0%). Multiple logistic regression analysis showed a striking geographical variation in prevalence of LSIL and HSIL. The prevalence of LSIL decreased with the increase in age, and increased with the duration of taking oral contraceptives. The prevalence of HSIL increased with the parity and the duration of taking oral contraceptives and was also significantly associated with the history of cervical cancer among mother and sisters. It is suggested that improvements in the participation rate of cervical neoplasia screening would promote women's health in Taiwan.

Adult↗
PubMed1994

Multifocal nature of adenolymphoma of the parotid.

The multifocal nature of adenolymphoma of the parotid salivary gland was studied in 24 patients who underwent parotidectomy. Twenty-six resected specimens were examined by a step-serial whole-organ sectioning technique; multiple adenolymphoma was found in 13. The maximum number of synchronous tumours in any gland was four. Salivary epithelial elements were found embedded within lymph nodes in nine resected specimens. Synchronous or metachronous bilateral tumours were found in eight patients. The multifocal nature of adenolymphoma of the parotid gland is demonstrated.

Adenolymphoma↗
PubMed1994

Cutaneous manifestations of non-01 Vibrio cholerae septicemia with gastroenteritis and meningitis.

A 58-year-old man with diabetes had fever and chills 5 days after ingestion of raw seafood. Nausea, vomiting, watery diarrhea, bilateral calf pain, and neck stiffness subsequently developed. Generalized edema and ecchymotic patches with a vesiculobullous eruption appeared on the extremities. Four blood cultures were positive for Vibrio cholerae non-01. The patient was successfully treated with antibiotics. This is the first documented case of V. cholerae non-01 septicemia with cutaneous lesions and meningitis in Taiwan.

Bacteremia↗
PubMed1994

Bowel perforation--a fatal complication following renal transplantation: a report of two cases.

From May 1983 to January 1993, 162 patients received renal transplantation at Taichung Veterans General Hospital. Two patients developed bowel perforation after this surgery. One was proved at 21 days and another, at 13 days after renal transplantation. Both patients died as a direct result of the perforation. From a review of literature, the average incidence is 2.7%, and the average mortality rate is 56.5%. Because of this high mortality rate, a high clinical suspicion, prompt and adequate surgical intervention, reduction of immunosuppressive agents and effective antibiotic coverage should contribute to a decline in mortality.

Adult↗
PubMed1993

Deoxyribonuclease of Syncephalastrum racemosum--enzymatic properties and molecular structure.

Among the isolated fungal species of soil, one filamentous fungus, Syncephalastrum racemosum, produces a relatively large amount of DNase. This enzyme has been purified to apparent homogeneity by column chromatography on DEAE-cellulose, hydroxylapatite, phenyl-Sepharose CL-4B, and Sephadex G-100. The active enzyme requires divalent metal ions and has an optimum pH of 7.0 with Mg2+ and 7.2 with Mn2+. This enzyme is an acidic glycoprotein with a pI 5.0 and is relatively unstable at low concentrations. The M(r) of the enzyme is 56,000 during gel filtration under nondenaturing conditions but is 28,000 during polyacrylamide gel electrophoresis in sodium dodecyl sulfate. These results suggest a structure consisting of two subunits. The subunits of the holoenzyme can be cross-linked with glutaraldehyde. The yield of N-terminal phenylthiohydantoin-alanine from the holoenzyme is 140% and that of one peptide (D-Y-V-S-S-G-Y-D-R), obtained from the tryptic digest is 160%, indicating that the native enzyme is composed of two identical subunits and probably has two active domains. Fungal DNase can be inactivated by Cu(2+)-iodoacetate under conditions that inactivate bovine pancreatic DNase. The specific activity (units/mg of protein) of fungal DNase is 6.5 times that of bovine DNase. The amino acid content of fungal DNase, relative to bovine DNase, is higher in Gly and lower in Ser and Val. The fungal N-terminal 40-residue sequence shows a high degree of homology with a consensus sequence derived from DNase of three mammalian species.

Amino Acid Sequence↗
PubMed1993

Removal of renal cell carcinoma extending into the right atrium using cardiopulmonary bypass, profound hypothermia and circulatory arrest.

A 65-year-old man presented with renal cell carcinoma of the right kidney with a tumor thrombus extending up the vena cava to the right atrium. Cardiopulmonary bypass, profound hypothermia and total circulatory arrest were used to create a bloodless field for excision of the renal cell carcinoma and its tumor thrombus. Acute respiratory failure and deep jaundice developed after the operation and the patient was transferred to the intensive care unit for critical care. After respiratory therapy and nutritional support, the liver function was restored. The endotracheal tube was weaned one month later. The patient has had total resolution of all symptoms and there is no evidence of tumor recurrence of distant metastases after 6 months follow-up.

Aged↗
PubMed1991

Chemical modification of bovine pancreatic deoxyribonuclease with phenylglyoxal--the involvement of Arg-9 and Arg-41 in substrate binding.

The inactivation of bovine pancreatic DNase by phenylglyoxal exhibits pseudo-first-order and pH-dependent kinetics. At 13.2 mM phenylglyoxal and 25 degrees C, the half-life of DNase is 8 min at pH 8.0 and 2 h at pH 6.7. Calcium, which binds to DNase, does not protect against or facilitate the reaction of DNase with the reagent. However, due to DNA-DNase interaction the half-life of DNase is approx. doubled in the presence of 0.2% (w/v) DNA. Modified DNase has apparently lost its ability to interact with DNA since it elutes behind native DNase on a Sepharose 4B column developed with buffer containing DNA. Complete inactivation of the enzyme is achieved when approx. 4 of the 12 arginines in DNase are modified at pH 6.7. The identification of the radioactive peptides, isolated from the proteolytic digest of [7-14C]phenylglyoxal-treated DNase, showed the four modified arginines to be Arg-9, -27, -30 and -41. Based on the data from dual labeling experiments using a mixture of DNase modified (without DNA protection) by radioactive phenylglyoxal and DNase modified (with DNA protection) by cold phenylglyoxal, it is concluded that Arg-27 and Arg-30 are essentially un-protected by DNA while Arg-9 and Arg-41 are protected part of the time. This conclusion agrees with the proposed substrate binding site in the three-dimensional structure of DNase (Suck, D., Lahm, A. and Oefner, C. (1988) Nature 332, 464-468) where Arg-9 and Arg-41 are among the residues responsible for interaction with DNA.

Amino Acid Sequence↗
PubMed1991

Primary retroperitoneal sarcomas--a report of 16 cases.

From November 1982 to August 1990, 16 patients with primary retroperitoneal sarcoma were treated in our hospital. The most frequent types of tumor were liposarcoma (6), malignant fibrous histiocytoma (3). The commonest clinical findings were palpable abdominal mass (14/16). In management of these patients; nine patients underwent complete resection of the tumor; three patients underwent partial resection of the tumor and four patients underwent biopsy only. The histology of tumor appeared to have prognostic significance. Patients suffering from liposarcoma (3/5) and malignant fibrous histiocytoma (1/2) survived the longest. With a mean follow up of 25.0 months, the three year overall survival rate of complete resection group was 50 per cent. No patients with partial resection and biopsy only group survive three years and the total three-years overall survival rate was 29%. The mean survival for patients after adjuvant chemotherapy and/or radiotherapy was similar to that after a radical operation alone. The prognosis of primary retroperitoneal sarcoma is grave and complete resection of the tumor as initial treatment seems to provide the only chance of cure for these patients.

Adolescent↗
PubMed1990

Whole organ sectioning of mixed parotid tumors.

A pathologic study involving 15 standard formal parotidectomy specimens was carried out using the whole organ sectioning technique. Histopathologic characteristics noted included the presence of exposed capsule, breaks of the capsule, capsular incompleteness, tumor ingrowth and thickness, cellularity, and lymphocytic infiltration. Tracings of histopathology slides were used to reconstruct the three-dimensional configuration of each tumor as viewed from different angles. No tumor had a smooth surface. At the extreme, two tumor lumps were connected by just a narrow waist. Separated tumors were not seen. In only one specimen did a lymph node contain an additional tumor in the form of an adenolymphoma. All tumors showed some exposed capsule or "bare area" to a degree affected mainly by the position of the tumor. Capsular damage was occasionally seen and was usually minor. Capsular incompleteness and tumor ingrowth make global capsular dissection unsafe. It is concluded that formal parotidectomy remains the operation of choice for pleomorphic adenoma of the parotid gland, although capsular dissection (otherwise termed enucleation) cannot be entirely avoided during the procedure.

Adenoma, Pleomorphic↗