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Biomedical subjects

K J Ho

Publications and source records attributed to K J Ho.

At least 19 recordsLinked to original sources
PubMed1992

Development and optimization of an enzyme-linked immunosorbent assay employing two murine monoclonal antibodies for absolute quantitation of human beta-glucuronidase.

We have developed and optimized an enzyme-linked immunosorbent assay (ELISA) for absolute quantitation of human beta-glucuronidase. This is a double antibody sandwich system employing two murine monoclonal antibodies specific for human beta-glucuronidase developed in our laboratories. The method involves (a) coating of the high binding polystyrene microtitration plate with the first antibody (7B6 IgG), (b) blocking of remaining active sites with 3% bovine serum albumin in phosphate-buffered saline, (c) application of samples, (d) addition of the biotinylated second antibody (6D2 IgG), (e) addition of streptavidin-horseradish peroxidase, and (f) development of color with o-phenylenediamine dihydrochloride-H2O2 and reading in a microplate reader at a wavelength of 490 nm. The method is highly sensitive with an optimal range of 10 to 100 ng/ml of the enzyme and is reproducible with intraday and interday precisions of 3.2 and 4.1%, respectively. The enzyme contents of 20 urine and 20 bile samples quantitated by this ELISA method were, respectively, 148 +/- 101 and 6380 +/- 3780 ng/ml (means +/- SD) which correlated well with their enzyme activities. Such a method for absolute quantitation of human beta-glucuronidase is essential for studying its pathophysiologic roles in cholelithiasis and carcinogenesis and can also be used clinically as an indicator for tissue damage or malignancy.

Animals↗
PubMed1979

Primary hemangiopericytoma of lung: radiography and pathology.

Two cases of primary hemangiopericytoma of the lung are reported. The massive tumors had radiographic features of round or oval contour, homogeneous opacity, well circumscribed smooth outline without calcification, and no compression of the surrounding lung tissue. They were rather homogeneous histologically, well encapsulated, and centrally located, but extended peripherally by replacement, instead of compression, of the pulmonary parenchyma. Review of the literature about 34 other cases suggests these are the usual characteristics of primary hemangiopericytomas of the lungs.

Cough↗
PubMed1979

Chronic systemic Dacron and Teflon embolization of a Beall model 103 mitral valve prosthesis.

A case is presented of chronic systemic Dacron and Teflon embolism arising from a Beall Model 103 mitral valve prosthesis installed 11 years earlier. The emboli induced intense foreign body reaction resulting in numerous microgranulomas throughout the body. Multiple microinfarctions in the brain accounted for repeated episodes of transient ischemic attacks. Wearing of the prosthesis with consequent embolic complications seems to be the inevitable terminal fate of such early models of the Beall valve. Regular assessment of the functional status of such prostheses, particularly those in place for more than 5 years, is strongly recommended.

Brain↗
PubMed1979

Characterization and determination of the activity of biliary beta-glucuronidase in rats.

beta-Glucuronidase activity determined in 100 diluted bile samples from 12 rats with bile duct fistula by using phenolphthalein glucuronide as substrate incubated at 56 degrees C and pH 6 was 636 +/- 650 (mean +/- S.D.) modified Sigma units/ml. The enzyme had an optimal pH of 6.0 and was inhibited slightly by cholate by markedly by chenodeoxycholate and deoxycholate. The biliary beta-glucuronidase had, thus, low activity under normal physiologic condition because of the high pH (8.1) and high bile salt content (20 mumoles/ml) of the bile. The enzyme kinetic studies revealed that the direct bilirubin was a competitive inhibitor to phonolphthalein glucuronide for the enzyme. The affinity of the former to the enzyme was 163 times that of the latter. The studies provided a method for measuring the true activity of biliary beta-glucuronidase (Vmax) devoid of interfering factors by measuring the enzyme velocity (v) in the diluted bile with at least five different concentrations of substrate (s). The plotting of (1/v) vs. (1/s) should yield the y intercept or (1/Vmax).

Animals↗
PubMed1979

Circadian rhythm of cholesterol biosynthesis: dietary regulation in the liver and small intestine of hamsters.

Sixty three hamsters were divided into two groups which were exposed to the same rigid lighting schedule (06(00)--18(00)) but fed at different time intervals (18(00)--22(00), and 08(00)--12(00), respectively) for five weeks. The cholesterol synthetic activity was then determined in liver, gastrointestinal tract, and kidney by in vivo incorporation of (1--14C)-acetate into cholesterol at different hours of the day. A remarkable circadian rhythm of the activity was found in the liver and small intestine, but not in other organs. Regardless of the lighting schedule, the nadir occurred, in both groups, always at the end of the fasting period and the peak four to six hours after feeding. The study clearly indicated the major role of diet in regulation of such phenomenon.

Animals↗
PubMed1977

Malignant hypertension as a cause of massive intestinal bleeding.

A forty-one year old man with a three year history of malignant hypertension developed massive rectal bleeding. A mesenteric arteriogram showed vascular changes compatible with necrotizing angitis. Histologic examination of the resected right hemicolon confirmed malignant hypertension as the cause of angitis.

Adult↗
PubMed1977

Cholesterol metabolism in patients with resection of ileum and proximal colon.

Compartmental analysis of the disappearance curve of serum cholesterol specific activity after an intravenous administration of a tracer does of cholesterol-4-14C was carried out in five patients with resection of the distal small intestine, cecum, and proximal colon. The data fit best a two compartment model in all five cases with the rapidly exchangeable pool of 16.6+/-3.2 g (mean +/- SD, 60% of the mean of 15 normal subjects) and the slowly exchangeable pool of 31.5 +/- 10.9 g (65%). The reduction of the pool sizes was associated with a shorter mean transit time of cholesterol, 22.15 +/- 8.07 days (40%) and increased turnover rate, 2.42 +/- 0.72g/ day (172%). Direct fecal analysis for the neutral sterols and bile acids derived from the exchangeable pool confirmed the turnover rate obtained from the compartmental analysis. The increased fecal excretion was mainly in the bile acid fraction. The study suggests that the ileal and proximal colon resection results in bile acid malabsorption which, in turn, increases hepatic cholesterol and bile acid synthesis. The synthetic rates, however, could not compensate totally for the excretory rate. Therefore, the pool size decreased to a new low steady state of equilibrium.

Adult↗
PubMed1977

Intestinal regulation of hepatic cholesterol synthesis: an hypothesis.

The serum cholesterol level in man is predominantly dependent on the rate of endogenous synthesis. The liver is the main site of cholesterol synthesis and this activity is in turn intimately related to the ingestion of food. When no food is present in the intestine, as during periods of total parenteral nutrition, both normal individuals and patients with familiar hypercholesterolemia show a pronounced lowering of their serum cholesterol. The establishment of a portacaval shunt makes this a permanent change. This and other evidence lead us to postulate the existence of an intestinal factor capable of stimulating hepatic cholesterogenesis. The function of this factor would be to increase the synthesis of chol

Animals↗