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Biomedical subjects

Y T Chang

Publications and source records attributed to Y T Chang.

108 records · Page 6Linked to original sources
PubMed1977

Growth of Mycobacterium lepraemurium in cultures of macrophages obtained from various sources.

Studies were made on the growth of Mycobacterium lepraemurium in cultures of macrophages obtained from various sources, such as bone marrow, spleen, and blood of mice. Macrophages were maintained in good condition for more than 12 weeks. Marked intracellular multiplication of M. lepraemurium was observed in cultures from all three sources. Whereas M. lepraemurium freshly prepared from the animals showed good growth in the cultures, those that were kept at 4 degrees C for 10 or 14 days showed no growth.

Animals↗
PubMed1969

Suppressive activity of streptomycin on the growth of Mycobacterium lepraemurium in macrophage cultures.

The effect of streptomycin on the growth of an obligate intracellular bacterium was studied in a new host-parasite cell system. The system consisted of Mycobacterium lepraemurium grown in cultures of mouse peritoneal macrophages. Since these organisms do not grow in bacteriological media, the influence of extracellular bacterial growth can be ruled out. The suppressive activity of streptomycin was observed in a total of five experiments. At the end of 4 weeks, the average number of organisms per macrophage for the controls was 65.7; for cultures with streptomycin at concentrations of 0.5, 1, 5, 10, 50, and 100 mug/ml of medium, it was 45.4, 38.3, 28.7, 22.7, 13.4, and 8.2, respectively. A good dose-response relationship was evident. M. lepraemurium which had been treated in macrophage cultures with various concentrations of the antibiotic for 6 to 8 weeks was used to infect fresh macrophages. These cultures were in turn treated with streptomycin. Resistance of the organisms to streptomycin did not occur.

Animals↗
PubMed1969

Morphological changes of Mycobacterium lepraemurium grown in cultures of mouse peritoneal macrophages.

Studies were made on morphological changes of Mycobacterium lepraemurium grown in cultures of mouse peritoneal macrophages. Two types of nonsolid or irregularly stained M. lepraemurium were observed. One type occurred in the growth phase of the organisms during the stage of preparation for bacillary multiplication. The nonsolid bacilli appeared as elongated organisms having pointed ends, isolated acid-fast dots, or faintly stained areas at the ends of the bacilli. It is possible that this irregularity in staining is due to a very gradual, versus an instantaneous, acquisition of acid-fast material during bacillary multiplication and maturation. Solid forms were again observed upon maturation. Nonsolid bacilli were also observed in macrophage cultures infected with autoclave-killed M. lepraemurium. Under these conditions there was an emergence of organisms which showed irregularly stained areas and various forms of deformity unaccompanied by elongation or multiplication. These irregularities were most probably due to the destructive process of digestion of bacillary protoplasm. The present study does not support the current hypothesis that all nonsolid acid-fast organisms are nonviable.

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PubMedDate not supplied

Obstructive jaundice caused by hepatocellular carcinoma: detection by endoscopic sonography.

Tumor thrombus in the extrahepatic biliary tree is a rare mechanism of obstructive jaundice. We present a patient with a minute hepatocellular carcinoma in the caudate lobe that invaded the common hepatic duct and caused biliary obstruction. Endoscopic sonography showed a tumor thrombus with central echogenicity and a "nodule-in-nodule" pattern and suggested the correct diagnosis.

Aged↗
PubMedDate not supplied

Binding of methyltrienolone to androgen receptors in human skin fibroblasts is enhanced by insulin.

Previous reports have suggested a relationship between hyperinsulinemia and increased androgen secretion leading to female virilization, but no report has been made of the effects of insulin on androgen receptors. The authors tested the in vitro effect of insulin on the binding of methyltrienolone (R1881) to androgen receptors of cultured genital skin fibroblasts preincubated with serum-free medium in the absence and presence of insulin (100 ng/mL, ie, 2600 microU/mL) for 18 hours at 37 degrees C. Insulin increased specific binding of R1881 by 35% (range, 13% to 75%). Scatchard analysis of androgen receptor binding demonstrated a similar increase in the number of binding sites, whereas binding affinity remained unchanged. The increase in androgen receptors was dose dependent (maximum effect at 25 ng insulin/mL) and time dependent (maximum effect occurring after 12 hours). DNA measurements indicated that insulin increased binding sites per cell rather than altering the cell number. Insulin increased total protein concentration to an extent similar to that observed for the increase in androgen receptor binding sites. Cycloheximide, but no actinomycin D, inhibited the effect of insulin on androgen receptor binding. The authors' data suggest that insulin induces an increase in the number of androgen receptors per cell as part of a general anabolic effect on cellular protein content.

Cycloheximide↗
PubMedDate not supplied

Are all nonsolid Mycobacterium leprae dead? Does a negative finding in the mouse foot pad indicate that there is actually no growth of M. leprae in the animals?

Ever since the discovery of the foot pad technic for growth of M. leprae in mice, investigators have overemphasized the laboratory results in clinical applications. Overenthusiasm has led to some dire results in the leprosy field. Two well-known examples can be cited, which are based on the presumption that: a) all the nonsolidly stained M. leprae are dead, and b) that a negative finding in the mouse foot pad indicates no growth of M. leprae in the animals. The former led clinical investigators to claim a false emergence of drug resistance after one year's treatment with a potent antileprosy drug, B663, which was almost abandoned for later clinical use. The latter led investigators to introduce a low-dose drug treatment, which resulted in a worldwide appearance of DDS resistance in leprosy. This paper outlines the reasoning that not all nonsolid M. leprae are dead, and that not all the organisms in the foot pads are detectable by the present standard foot pad/ M. leprae technic.

Animals↗
PubMedDate not supplied

Growth of macrophages obtained from various sources.

Techniques to obtain macrophages from various sources of the mouse were reported. The following sources were included: peritoneal exudate, alveolar lavage, blood leucocytes, bone marrow, spleen, liver, lungs, lymph nodes, thymus, thyroid, heart muscle, kidney, and subcutaneous cover glass implants. Human blood macrophages were also included. Long-term cinemicrographic studies revealed sustained good growth of these macrophages. Cell multiplication was detected in all of these cultures except those obtained from the peritoneal exudate. Pure cultures of macrophages were obtained from blood of the mouse and human. Macrophages obtained from other sources were accompanied by some growth of fibroblasts. Methods to eliminate the fibroblasts in cultures were discussed.

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