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Biomedical subjects

K J Ho

Publications and source records attributed to K J Ho.

At least 73 records · Page 4Linked to original sources
PubMed1985

Human beta-glucuronidase. Studies on the effects of pH and bile acids in regard to its role in the pathogenesis of cholelithiasis.

Human bile contains a considerable amount of endogenous beta-glucuronidase. The effects of pH and bile acids on its activity have been studied in regard to its role in the pathogenesis of cholelithiasis. beta-Glucuronidase, purified from human liver to homogeneity, was structurally stable between pH 4 and 10, but was active only over a much narrower range of pH, with a pH optimum of 5.2. The inactivation below pH 4 was due to its irreversible denaturation, whereas the inactivation at higher pH was due to a true reversible pH effect on the enzyme velocity. Kinetic studies revealed that hydrogen ion acted as a substrate-directed activator of the free enzyme, but not the enzyme-substrate complex, with a molecular dissociation constant of 4 X 10(-6). The enzyme activity was not affected by unconjugated bile acids, primarily due to their extremely low water solubility. Conjugated bile acids, on the other hand, exerted heterogeneous and pH-dependent effects on the enzyme. At pH 5.2, taurocholic acid and glycocholic acid were substrate-directed activators of the enzyme; taurochenodeoxycholic acid and taurodeoxycholic acid, competitive inhibitors; and glycochenodeoxycholic acid and glycodeoxycholic acid, mixed inhibitors. At pH 7.0 all taurine and glycine conjugates behaved as substrate-directed activators. Though beta-glucuronidase activity at pH 7 was only 23% of its maximal activity at pH 5.2, conjugated bile acids tended to restore its activity to a certain extent at pH 7. Thus, endogenous beta-glucuronidase could play a significant role in pigment cholelithiasis.

Bile Acids and Salts↗
PubMed1985

Appendicolith. Significance in acute appendicitis and demonstration by computed tomography.

A case of periappendical abscess is presented in which the diagnosis was made by demonstration of an appendicolith in a large abscess cavity by computed tomography (CT) in conjunction with the clinical signs and symptoms. However, the appendicolith was not detected by plain film radiography. We stress that CT is more sensitive in detection of such small calcified bodies than plain film radiography and that the true incidence of appendicolith in acute appendicitis could be higher than that reported previously.

Abscess↗
PubMed1985

Metastatic mediastinal neoplasm masquerading as aortic dissection: a skip sign on computed tomography for their distinction.

Four years after undergoing a left lower lobe lobectomy for squamous cell carcinoma, a 77-year-old man presented with a mass lesion in the left upper mediastinum associated with chest pain. Computed tomography revealed a homogeneous density immediately adjacent to the aortic arch and thoracic aorta consistent with aortic dissection. Upon thoracotomy, however, the lesion was found to be an oat cell carcinoma. Retrospective review of the computed tomography scans detected a normal segment of descending aorta, indicating the interruption of the paraaortic lesion. Such a skip sign can be used to rule out aortic dissection.

Aged↗
PubMed1985

Massive mediastinal Hodgkin's disease with calcification masquerading teratocarcinoma: differentiation by computed tomography.

Two young patients with similar radiographic manifestations of massive opacification of left hemithorax with scattered calcification highly suggestive of mediastinal teratocarcinoma are reported. By biopsy, one patient was proved to have teratocarcinoma and the other patient was proved to have Hodgkin's disease. Retrospective review indicates that spontaneous neoplastic calcification in Hodgkin's disease, though rare, can occur prior to therapy. Computed tomography is useful in distinguishing such cases of Hodgkin's disease from teratocarcinoma by demonstrating the involvement of the posterior mediastinum and homogeneous density.

Adult↗
PubMed1985

Differential quantitation of urinary beta-glucuronidase of human and bacterial origins.

A method for the differential quantitation of urinary beta-glucuronidases of human and bacterial origins is presented. The activity of human enzyme at pH 6.5 was 36 per cent of its peak activity at pH 5.0 while the activity of bacterial enzyme at pH 5.0 was 20 per cent of its peak activity at pH 6.5. By simultaneous determination of the activity in a mixture of the enzymes of these two sources at both pH 5.0 and 6.5 and by simple mathematic proportion the individual activity of human and bacterial enzymes could be determined separately. This provides a quick method for differential diagnosis between bacterial and non-bacterial disease of the urinary system.

Escherichia coli↗
PubMed1985

Human hepatic beta-glucuronidase: an enzyme kinetic study.

beta-Glucuronidase (EC 3.2.1.31) was purified from human liver and its activity was determined by enzyme kinetic method employing phenolphthalein glucuronic acid (PGA) and conjugated bilirubin, primarily bilirubin diglucuronide purified from human bile, as substrates in the absence or presence of D-glucaro-1,4-lactone. The enzyme was capable of acting on both PGA and conjugated bilirubin with Michaelis constants of 0.435 mmol/l at 56 degrees C and 1.02 mmol/l at 37 degrees C, respectively. Both reactions were beta-glucuronidase-specific because both were inhibited by D-glucaro-1,4-lactone in a competitive fashion. Conjugated bilirubin acted as a noncompetitive inhibitor of the enzyme for PGA in a two-substrate system. The study indicates that these two substrates bind at different catalytic sites of the enzyme and, on molar base, conjugated bilirubin had higher affinity for the enzyme and less degree of inhibition by D-glucaro-1,4-lactone than PGA. Whether such catalytic sites are also common for other beta-D-glucuronid ethers and esters remains to be proven.

Bilirubin↗
PubMed1984

Computed tomographic distinction of submucosal lipoma and adenomatous polyp of the colon.

Described here is a patient with 2 large pedunculated colonic tumors detected by barium enema radiography. By computed tomography (CT) 1 was found to be a submucosal lipoma characterized by oval shape, smooth demarcation, and homogeneous density with a CT number of -68 HU, whereas the other was an adenomatous polyp with slightly fuzzy outline and a much higher CT number. This case indicates that CT can be a definitive diagnostic modality for distinguishing between a colonic lipoma and other solid or cystic tumor of the colon.

Barium Sulfate↗
PubMed1984

Computed tomography evaluation of bilateral bronchostenosis caused by sclerosing granulomatous mediastinitis: a complication of histoplasmosis.

A proved case of histoplasmosis with sclerosing granulomatous mediastinitis complicated by severe bilateral bronchostenosis in a 28-year-old woman is reported. The case demonstrates that this relatively benign disease can lead to grave consequences and that computed tomography is extremely useful in the evaluation of this mediastinal lesion, particularly when plain chest radiography is noncontributory.

Adult↗
PubMed1984

Small cell carcinoma of the esophagus: evidence for a unified histogenesis.

Four cases of small cell carcinoma of the esophagus, histologically indistinguishable from oat cell carcinoma of the lung, were studied by electron microscopy. Three were composed largely of small cells with neurosecretory granules characteristic of APUD (amine precursor uptake and decarboxylation) cells. Two of these three cases also contained foci of squamous or glandular differentiation, or both. The fourth case was classified as reserve cell carcinoma with squamous differentiation, since the tumor cells were devoid of neurosecretory granules but contained desmosomes and bundles of intracytoplasmic tonofilaments. The evidence provided by these four cases and also by the 48 cases previously reported in the literature supports our hypothesis that a totipotent primitive cell serves as the common precursor for squamous cell, adeno-, and small cell carcinoma of the esophagus. The latter can be subdivided into oat cell and reserve cell carcinomas, both having the propensity for further squamous and glandular differentiation. The hypothesis can also be applied to lung cancer.

Carcinoma, Small Cell↗
PubMed1984

Strongyloidiasis manifested as asthma.

We have described a case of infection with Strongyloides stercoralis manifested as asthma. As a result of treatment with corticosteroids, hyperinfection developed with aggravation of symptoms. The patient's condition improved only after thiabendazole therapy was instituted and corticosteroids were discontinued.

Adult↗
PubMed1984

Mucoepidermoid carcinoma of the larynx: a light and electron microscopic study with emphasis on histogenesis.

Using light and electron microscopy, we recently studied a mucoepidermoid carcinoma of the larynx and reviewed 66 cases reported in the literature. Histologic features showed the origin of the tumor from the ductule of submucosal seromucous glands. The tumor was characterized by a mixed pattern of adenocarcinoma and squamous cell carcinoma. Six types of neoplastic cells were observed under the electron microscope, representing various stages of differentiation of the intermediate cells toward mucus-secreting, keratin-forming, and lumen-lining cells. The true incidence of this type of neoplasm could be higher than is believed because of its frequent misdiagnosis as squamous cell carcinoma. The importance of its differentiation from squamous cell carcinoma is emphasized because this tumor responds poorly to radiation therapy.

Carcinoma↗
PubMed1984

Postoperative malignant seroma: CT demonstration of its formation mechanism.

A malignant seroma in the subscapular region of the chest wall developed postoperatively in a 51-year-old man with a malignant right pleural mesothelioma treated with extrapleural pneumonectomy. Computed tomography revealed the direct communication of the seroma with the hydrothorax. Correlation of CT and pathologic findings is made and the mechanism for the development of such a malignant seroma is proposed.

Exudates and Transudates↗