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Biomedical subjects

C H Chan

Publications and source records attributed to C H Chan.

At least 145 records · Page 8Linked to original sources
PubMed1985

Comparative studies on epimastigote and metacyclic stages of Trypanosoma cruzi. II. Selective lysis by rodent sera.

In a series of immunological studies on Trypanosoma cruzi, the lytic titers of epimastigotes and metacyclic trypomastigotes by sera obtained from normal and infected rodents were compared. Lysis of culture forms of T. cruzi by normal mouse or rat serum was restricted to the epimastigote form. Freezing reduced the lytic titers of rodent sera. This serum lytic activity was also depressed during the acute infection phase. Metacyclic trypomastigotes were more resistant than epimastigotes to both nonspecific and specific lysis by sera, However, provided with fresh complement, antisera collected from mice or rats lysed 12-26% of metacyclic trypomastigotes.

Animals↗
PubMed1984

Loxapine abuse.

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Adult↗
PubMed1983

Hepatic involvement in hairy cell leukemia.

Nineteen patients with hairy cell leukemia were studied in order to define the hepatic changes in this disease and to correlate the morphologic changes in the liver with the clinical and biochemical findings. Although only eight of the patients had hepatomegaly, all 19 had microscopic mononuclear cell infiltration in the sinusoids or the portal areas or both. The severity of mononuclear infiltration in the liver correlated poorly with the size of the liver or spleen, the biochemical changes, or number of hairy cells in the blood. Abnormal serum biochemical values were present occasionally and were usually due to associated diseases or to complications of this disease. Elevated serum alkaline phosphatase activity was noted in four patients; three of them had granulomatous lesions in the liver. Unless the characteristic "clear cell" pattern is seen, the hepatic mononuclear cell infiltration may not be diagnostic of hairy cell leukemia and, in many instances, may not even be suggestive of neoplasia. A new technique for demonstrating tartrate-resistant acid phosphatase activity in methacrylate-embedded sections was developed, which allowed identification of hairy cells in the liver biopsy specimens of all five patients so studied. The authors concluded that liver involvement is common in this disease.

Acid Phosphatase↗
PubMed1982

The phospholipids of the hepatic endoplasmic reticulum. Structural change in liver injury.

Endoplasmic-reticulum phospholipids were measured during the first hour after carbon tetrachloride administration to male Sprague-Dawley rats and compared with carbon tetrachloride challenge of microsomes from control animals in vitro. The extracted lipids were separated by high-pressure liquid chromatography. No significant differences in the abundance of phosphatidylserine, phosphatidylethanolamine, phosphatidylinositol or phosphatidylcholine were found after either treatment when compared with untreated controls. Diene conjugate formation in each separated phospholipid was determined by measuring A(232) and expressed on the basis of lipid phosphorus. Phosphatidylserine was peroxidized 6-fold greater than in controls after challenge in vivo, reaching maximal change after 15min, whereas the other phospholipids showed little or no alteration. Fatty acid composition analysis was performed by g.l.c. after transesterification of individual phospholipids. Phosphatidylserine revealed two types of response: an abrupt decrease in relative abundance of oleic acid (C(18:1)) and linoleic acid (C(18:2)) without further loss and a slower, linear decrease in arachidonic acid (C(20:4)) over the first hour. Similar changes were not seen in other phospholipids. In the ;in vitro' model, the relative amounts of the phospholipids do not change. The extent of peroxidation was greater in all the phospholipids than found in vivo, with phosphatidylserine peroxidized to the greatest extent. These data suggest that carbon tetrachloride injury in vivo produces an early peroxidative event and that a specific phospholipid (phosphatidylserine) is selectively modified, although maintaining its relative concentration in the membrane. Dissection of this process in vitro will require refinement of existing systems to reduce the non-specific changes associated with the model system.

Adenosine Diphosphate↗
PubMed1981

Analysis of the phospholipid of the nuclear envelope and endoplasmic reticulum of liver cells by high pressure liquid chromatography.

A method is described for the separation and analysis of phospholipids from rat-liver nuclear envelope and endoplasmic reticulum. The procedure employs a liquid environment, to which antioxidants can be added, and results in separation of NL, PE, PI, PS, and PC in 99% purity in 12 min; analytical columns and a radial compression system may be employed. The procedure results in phospholipids with a large proportion of highly unsaturated fatty acids; some differences in fatty acid distributions were found when nuclear envelope phospholipid fractions were compared with the corresponding fractions from endoplasmic reticulum.

Animals↗
PubMed1977

Hepatitis B virus infection and primary hepatocellular carcinoma.

Ninety-three patients with biopsy-proven primary hepatocellular carcinoma (PHC) from Uganda, Zambia, and the United States were examined for serologic evidence of hepatitis B virus (HBV) infection. Patients were tested for hepatitis B surface antigen (HBsAg) and its antibody (anti-HBs), antibody to the hepatitis B core antigen (anti-HBc), hepatitis B e antigen (HBeAg), and its antibody (anti-HBe). Active HBV infection, as indicated by positive tests for HBsAg (with or without anti-HBs) and anti-HBc (without anti-HBs), was present in 62% of PHC patients (58 of 93), in contrast with 10% of African controls (9 of 90), and less than 1% of most United States adult populations reported in the literature. The presence of HBeAg or anti-HBe was rare among PHC patients and controls.

Adolescent↗
PubMed1976

Improvement of depression and parkinsonism during ECT: a case study.

Improvement in signs of parkinsonism and symptoms of depression was observed in a patient with Parkinson's disease who underwent a course of ECT for depression. Empirically this patient was observed by a blind rater to show a pattern of improvement in parkinsonian signs similar to that observed in parkinsonian patients treated with L-dopa. The time course of improvement of this patient's depression was also seen to parallel improvement in his Parkinson's disease. These results are consistent with the hypothesis that ECT increases catecholamine synthesis and more specifically would be evidence that ECT improves depression by increasing norepinephrine synthesis.

Aged↗
PubMed1975

Assessment of susceptibility of ampicillin-resistant enterobacteria to cephalosporins.

The susceptibility of 103 ampicillin-resistant strains of enterobacteria to two cephalosporins was assessed by turbidimetric monitoring and disk diffusion tests. The results obtained suggest that in most cases a correlation exists between the suppression of growth of a dense bacterial culture for a therapeutically acceptable period by a fixed, high concentration of cephalosporin and a large zone of inhibition (>/=24 mm) using a high potency disk. This correlation was found to hold good when a moderate, subconfluent inoculum and commercially obtained blood-agar plates were used for the disk test, but not when the stringent conditions required by the Kirby-Bauer test (which demands a dense inoculum on Mueller-Hinton agar) were employed. Better correlation was obtained with cephaloridine than with cephalothin. This approach to the interpretation of disk diffusion tests gives a grossly different picture of the susceptibility of ampicillin-resistant enterobacteria to cephalosporins than do conventional minimal inhibitory concentration-based correlations.

Ampicillin↗