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Biomedical subjects

J C Li

Publications and source records attributed to J C Li.

At least 73 records · Page 4Linked to original sources
PubMed1991

Study on the ultrastructure of the peritoneal stomata in humans.

In 16 human specimens the topography and organization of stomata and mesothelial cells of the diaphragmatic, pelvic wall and anterior abdominal wall peritoneum were studied by transmission electron microscopy, scanning electron microscopy and the image processing technique. The mesothelial cells were organized into two discrete populations, cuboidal cells and flattened cells. The stomata were found only among cuboidal cells, either on the muscular portion or on the tendinous portion of the diaphragm. The size and shape of stomata, which were arranged in a cluster or a strip, were often irregular. The average area of a stoma on the muscular portion was 10.43 +/- 1.61 microns2, on the tendinous portion 7.93 +/- 1.67 microns2. Stomata opened to submesothelial connective tissue, under which numerous lymphatics were observed. Stomata were not discovered in the pelvic and anterior abdominal wall peritoneum. In animal experiments intraperitoneally injected trypan blue particles were rapidly removed from the peritoneal cavity through stomata of the diaphragmatic peritoneum in rabbits. It is suggested that stomata may be the main pathway for draining matter from the peritoneal cavity and that the diaphragmatic peritoneum shows the strongest absorption in all parts of the peritoneum.

Abdominal Muscles↗
PubMed1990

Inhibition of human cancer cell growth by periodate-oxidized 3-aminopyridine adenine dinucleotide phosphate.

1. Periodate-oxidized 3-aminopyridine-adenine dinucleotide phosphate inhibited the proliferation of oral epithelium cancer and breast cancer cell lines. 2. The fast growing less differentiated embryonic kidney cell was more affected by the reagent then the embryonic lung fibroblast cell. 3. Incorporation of [3H]leucine of the treated cancer cells was inhibited. Incorporation of [3H]uridine was increased. Incorporation of [3H]thymidine was first increased and then decreased. 4. Tumor malic enzyme activity was inhibited by the reagent; but the treated cells did not show any difference in malic enzyme or glucose-6-phosphate dehydrogenase levels.

Adenine Nucleotides↗
PubMed1990

Palliative radiotherapy of cerebral metastasis from lung cancer.

Cerebral metastasis is a common manifestation of lung cancer. Presenting signs and symptoms are often grave, and consequently often result in patients being debilitated for the rest of their lives. Radiotherapy has been used to treat a majority of these cases, and is considered as the treatment of choice. At Mackay Memorial Hospital, we collected from 1982 to 1985, the records of 42 lung cancer patients with brain metastasis. All the cases had a histological diagnosis of primary lung cancer; most of them were squamous cell carcinoma and adenocarcinoma; only two cases were small cell carcinoma. The diagnosis of brain metastasis was established by computed tomographic scans of the brain and radioisotopic brain scans. Of the 42 cases, 22 received palliative radiotherapy from a cobalt-60 teletherapy machine to the whole brain for a total dose of 30 Gray (Gy) in 10-15 fractions over a time span of 2 to 3 weeks, while the remaining patients only received medical treatment (e.g. cranial decompression with mannitol, steroids, etc.). Most of the patients have already died. In our study, those who received radiotherapy attained considerable palliation of their symptoms and signs, including improvement of their general performance status and neurological function. Although the treatment did not prolong the patient's survival, it did decrease considerably the disability caused by the metastatic disease.

Adenocarcinoma↗
PubMed1989

DNA fragmentation in permeabilized cells and nuclei. The role of (Ca2+ + Mg2+)-dependent endodeoxyribonuclease.

Permeabilized mammalian cells and isolated nuclei were used to study various aspects of DNA replication and repair. The present paper describes a progressive fragmentation of parental DNA in human lymphoblastoid cells that were permeabilized with L-alpha-lysophosphatidylcholine or with saponin and incubated at 37 degrees C in a DNA-synthesis mixture. The formation of DNA single-strand breaks (measured by alkaline elution) was linear with the time of incubation and was temperature-dependent. It was prevented by deleting Mg2+ or both Mg2+ and Ca2+ from the incubation mixture, or by the addition of EDTA. It was increased by deleting the components necessary for DNA synthesis, and by substituting Mn2+ for Mg2+ and Ca2+. DNA strand breaks also accumulated in isolated nuclei incubated in a DNA synthesis mixture, but not when Mg2+ was omitted. These results suggest that DNA fragmentation in permeabilized cells and nuclei was due to an activation of (Ca2+ + Mg2+)-dependent endodeoxyribonucleases. The integrity of template DNA needs to be ascertained when the conditions for measuring DNA synthesis in permeabilized cells or in nuclei are formulated.

Cell Line↗
PubMed1989

Mycologic investigation on Rhizomys pruinous senex in Guangxi as natural carrier with Penicillium marneffei.

To study the natural carrier of P. marneffei experiments were done in 16 Rhizomys pruinous senex, a species of bamboo rats trapped in various districts of Guangxi. The results of mycological cultivation demonstrated that the natural positive carrier rate of bamboo rats was 93.1%. Among the internal organs taken for culture, the lung had the highest positive rate, 87.5%; next in decreasing order was the liver (56.3%), spleen (56.3%) and mesentery lymph node (50%). Thus, it is reasonable to consider that bamboo rats are a reservoir host of P. marneffei. In this paper, the colony shape and microstructure of P. marneffei, isolated from bamboo rats, are described. A preliminary discussion is given on the epidemiological relations between bamboo rats and human Penicilliosis marneffei.

Animals↗
PubMed1988

High malic enzyme activity in tumor cells and its cross-reaction with anti-pigeon liver malic enzyme serum.

Rabbit antibodies against pigeon liver malic enzyme (EC 1.1.1.40) were prepared. The antiserum gave single precipitation line with crude pigeon liver extract. Cross reaction was observed with partially purified malic enzyme or crude extract from chicken liver. Positive cross reaction was also observed with the concentrated cytosolic fraction of two human carcinoma cell lines which were demonstrated to contain high malic enzyme activity. All other proteins examined did not react with the antibodies. When purified pigeon liver malic enzyme was mixed with the antiserum in vitro, a time-dependent inactivation of the enzyme activity was observed. Protection of the enzyme activity against antiserum inactivation was afforded by NADP+ or L-malate. Metal Mn2+ gave little protection.

Animals↗
PubMed1988

Dynamic amaurosis fugax secondary to compression of vertebral artery.

Transient unilateral loss of vision can be a manifestation of ipsilateral carotid disease; whereas transient visual impairment affecting both eyes simultaneously suggests vertebral basilar-artery insufficiency. We present such a case where the symptoms were related to head position. Congenital anomalies of the vertebral arteries were found on four-vessel cervical angiography.

Adult↗
PubMed1987

Progressive formation of DNA lesions in cultured Ehrlich ascites tumor cells treated with hydroxyurea.

We have previously demonstrated an accumulation of strand breaks in mature DNA of cultured Ehrlich ascites tumor cells treated with methotrexate. We postulated that the strand breaks arose from unrepaired spontaneous DNA lesions. The present study describes a progressive accumulation of strand breaks in mature DNA of Ehrlich ascites cells treated with hydroxyurea (HU). Strand breaks were determined by alkaline elution. Accumulation of strand breaks was dependent on the length of incubation (0-16 h) and on HU concentration (0-10 mM). About 70% of strand breaks were repaired when cells were incubated without HU. About 67% of strand breaks were prevented by 0.4 mM deoxyadenosine, deoxyguanosine, and deoxycytidine, with or without thymidine. Prevention was less effective by deoxyadenosine and deoxyguanosine and ineffective by deoxycytidine. Free radical scavengers did not prevent strand breaks. S-phase cells accumulated about twice the number of strand breaks as non-S-phase cells. Cell survival decreased in proportion to the increase in HU concentration (0-10 mM). The results demonstrate that lack of purine, as well as of pyrimidine, nucleotides results in strand breaks in mature DNA, suggest that HU cytotoxicity is due to fragmentation of mature DNA, and caution against the use of HU in DNA repair studies.

Animals↗
PubMed1987

Overcoming retention time shifts as a source of error in HPLC analysis.

When used for physiologic fluid analysis, shifts in retention times, even at constant flow rates, can cause integrators to function inadequately as tools for peak identification and thus result in concentration errors. A system capable of data collection, identification, quantification, and long-term storage that primarily uses retention times only for identification of elution sequence is described. Operator identification, aided by manipulation of x and y coordinates of the chromatograph, enhances positive identification of compounds for the experienced chromatographer.

Amino Acids↗